Houston, TX, United States
Houston, TX, United States

William Marsh Rice University, commonly referred to as Rice University or Rice, is a private research university located on a 295-acre campus in Houston, Texas, United States. The university is situated near the Houston Museum District and is adjacent to the Texas Medical Center. It is consistently ranked among the top 20 universities in the U.S. and the top 100 in the world.Opened in 1912 after the murder of its namesake William Marsh Rice, Rice is now a research university with an undergraduate focus. Its emphasis on education is demonstrated by a small student body and 5:1 student-faculty ratio, among the lowest in the top American universities including the Ivy League. The university has produced 101 Fulbright Scholars, 11 Truman Scholars, 24 Marshall Scholars, 12 Rhodes Scholars, 3 Nobel Laureates, 2 Pulitzer Prize winners, and at least 2 deceased and 2 living billionaires. The university has a very high level of research activity for its size, with $115.3 million in sponsored research funding in 2011. Rice is noted for its applied science programs in the fields of artificial heart research, structural chemical analysis, signal processing, space science, and nanotechnology. It was ranked first in the world in materials science research by the Times Higher Education in 2010. Rice is a member of the Association of American Universities.Rice is noted for its entrepreneurial activity, and has been recognized as the top ranked business incubator in the world by the Stockholm-based UBI Index for both 2013 and 2014.The university is organized into eleven residential colleges and eight schools of academic study, including the Wiess School of Natural science, the George R. Brown School of Engineering, the School of Social science, and the School of Humanities. Graduate programs are offered through the Jesse H. Jones Graduate School of Business, School of Architecture, Shepherd School of Music, and Susanne M. Glasscock School of Continuing Studies. Rice students are bound by the strict Honor Code, which is enforced by a uniquely student-run Honor Council.Rice competes in 14 NCAA Division I varsity sports and is a part of Conference USA, often competing with its cross-town rival the University of Houston. Intramural and club sports are offered in a wide variety of activities such as jiu jitsu, water polo, and crew. Wikipedia.


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Patent
Rice University, Baylor College of Medicine and Texas Heart Institute | Date: 2015-02-20

Systems and methods for deploying and securing conductive materials to a region of tissue may utilize a catheter. The catheter may provide a tip with one or more detachable sections or may provide an adjustable opening. A lumen of the catheter may provide a conductive material, such as a filament, fiber, network or patch of carbon nanotubes (CNTs) or carbon nanofibers (CNFs). In some embodiments, the conductive materials may be coupled to securing mechanisms, such as screws, clips, anchors, alligator clips, or anchors with barbs, which can be actuated to attach the conductive materials to desired regions of tissue. In some embodiments, the catheter may provide a needle tip that allows the conductive material to be embedded into desired regions of tissue by inserting the needle into the tissue.


The present invention provides an oligonucleotide composition including a blocker and a first primer oligonucleotide. The blocker oligonucleotide includes a first sequence having a target-neutral subsequence and a blocker variable subsequence. The non-target specific subsequence is flanked on its 3 and 5 ends by the target-neutral subsequence and is continuous with the target-neutral subsequence. The first primer oligonucleotide is sufficient to induce enzymatic extension; herein the first primer oligonucleotide includes a second sequence. The second sequence overlaps with the 5 end of the target-neutral subsequence by at least 5 nucleotides; herein the second sequence includes an overlapping subsequence and a non-overlapping subsequence. The second sequence does not include the non-target specific subsequence.


Patent
Rice University | Date: 2016-09-23

Embodiments of the present invention provide methods of preparing functionalized graphene nanoribbons by (1) exposing a plurality of carbon nanotubes to an alkali metal source in the presence of an aprotic solvent, wherein the exposing opens the carbon nanotubes; and (2) exposing the opened carbon nanotubes to an electrophile to form functionalized graphene nanoribbons. Such methods may also include a step of exposing the opened carbon nanotubes to a protic solvent in order to quench any reactive species on the opened carbon nanotubes. Further embodiments of the present invention pertain to graphene nanoribbons formed by the methods of the present invention. Additional embodiments of the present invention pertain to nanocomposites and fibers containing the aforementioned graphene nanoribbons.


Patent
Rice University | Date: 2015-05-06

In some embodiments, the present disclosure pertains to methods of forming calcium-silicate-hydrate particles by mixing a calcium source with a silicate source. In some embodiments, the mixing comprises sonication. In some embodiments, the mixing occurs in the presence of a surfactant and a solvent. In some embodiments, the methods of the present disclosure further comprise a step of controlling the morphology of the calcium-silicate-hydrate particles. In some embodiments, the step of controlling the morphology of calcium-silicate-hydrate particles comprises selecting a stoichiometric ratio of the calcium source over the silicate source. In some embodiments, the formed calcium-silicate-hydrate particles have cubic shapes. In some embodiments, the formed calcium-silicate-hydrate particles have rectangular shapes. In some embodiments, the formed calcium-silicate-hydrate particles are in the form of self-assembled particles of controlled shapes. Additional embodiments of the present disclosure pertain to compositions that contain the calcium silicate-hydrate particles of the present disclosure.


In some embodiments, the present disclosure pertains to methods of producing a graphene material by exposing a polymer to a laser source. In some embodiments, the exposing results in formation of a graphene from the polymer. In some embodiments, the methods of the present disclosure also include a step of separating the formed graphene from the polymer to form an isolated graphene. In some embodiments, the methods of the present disclosure also include a step of incorporating the graphene material or the isolated graphene into an electronic device, such as an energy storage device. In some embodiments, the graphene is utilized as at least one of an electrode, current collector or additive in the electronic device. Additional embodiments of the present disclosure pertain to the graphene materials, isolated graphenes, and electronic devices that are formed by the methods of the present disclosure.


The present disclosure describes the thermodynamic design and concentrations necessary to design probe compositions with desired optimal specificity that enable enrichment, detection, quantitation, purification, imaging, and amplification of rare-allele-bearing species of nucleic acids (prevalence <1%) in a large stoichiometric excess of a dominant-allele-bearing species (wildtype). Being an enzyme-free and homogeneous nucleic acid enrichment composition, this technology is broadly compatible with nearly all nucleic acid-based biotechnology, including plate reader and fluorimeter readout of nucleic acids, microarrays, PCR and other enzymatic amplification reactions, fluorescence barcoding, nanoparticle-based purification and quantitation, and in situ hybridization imaging technologies.


Patent
Rice University | Date: 2016-08-15

The invention relates to recombinant microorganisms that have been engineered to produce various chemicals using genes that have been repurposed to create a reverse beta oxidation pathway. Generally speaking, the beta oxidation cycle is expressed and driven in reverse by modifying various regulation points for as many cycles as needed, and then the CoA thioester intermediates are converted to useful products by the action of termination enzymes.


Patent
Rice University | Date: 2015-05-07

Plasmonic pixels may provide an array of nanoparticles in a desired arrangement on a substrate, and may be overcoated with a top layer. The nanoparticles may be nanorods, nanoshells, nanoparticles, spiky shells, cubes, triangles, prisms, disks, nanowires, gratings, Fano structures, and/or other single or coupled nano structures. The array of nanoparticles may support two polarized surface plasmon resonances. Further, a plasmon response of the array of nanoparticles may be diffractively coupled. The nanoparticles may be arranged in a square or hexagonal array. The color of the plasmonic pixel may be controlled by the plasmon response of the nanoparticles, a distance between nanoparticles along axial directions, and/or a method of excitation.


Embodiments of a capo and fretting component are described. In certain embodiments, the fretting component is threaded onto a crossbar configured to overlie the instrument strings when in use and to pivot with respect to the crossbar so as to contact and press the strings against a fret on the instrument neck. The fretting component is offset with respect to the attachment mechanism of the capo, allowing the attachment mechanism to be offset on the neck of the instrument from where it would normally be positioned to achieve a comparable fretting effect.


A method includes generating, by a wireless device, a sounding packet. The method includes sending, by the wireless device, copies of the sounding packet using a beam former and an antenna array to a second wireless device. Each copy of the copies of the sounding packet is sent using different beam weights. The method includes, in response to sending the copies of the sounding packet, obtaining, by the wireless device, a first correction beam weight and a second correction beam weight from the second wireless device and sending, by the wireless device, data to the second wireless device using the first correction beam weight and the second correction beam weight.


Patent
Rice University | Date: 2017-02-15

The invention relates to a mutant strain of bacteria, which either lacks or contains mutant genes for several key metabolic enzymes, and which produces high amounts of succinic acid under anaerobic conditions.


Sanchez-Adams J.,Rice University | Athanasiou K.A.,University of California at Davis
Biomaterials | Year: 2012

Adult stem cells from the dermal layer of skin are an attractive alternative to primary cells for meniscus engineering, as they may be easily obtained and used autologously. Recently, chondroinducible dermis cells from caprine skin have shown promising characteristics for cartilage tissue engineering. In this study, their multilineage differentiation capacity is determined, and methods of expanding and tissue engineering these cells are investigated. It was found that these cells could differentiate along adipogenic, osteogenic, and chondrogenic lineages, allowing them to be termed dermis isolated adult stem cells (DIAS cells). Focusing on cartilage tissue engineering, it was found that passaging these cells in chondrogenic medium and forming them into self-assembled tissue engineered constructs caused upregulation of collagen type II and COMP gene expression. Further investigation showed that applying transforming growth factor β1 (TGF-β1) or bone morphogenetic protein 2 (BMP-2) to DIAS constructs caused increased sulfated glycosaminoglycan content. Additionally, TGF-β1 treatment caused significant increases in compressive properties and construct contraction. In contrast, BMP-2 treatment resulted in the largest constructs, but did not increase compressive properties. These results show that DIAS cells can be easily manipulated for cartilage tissue engineering strategies, and may also be a useful cell source for other mesenchymal tissues. © 2011 Elsevier Ltd.


Hu H.,Swinburne University of Technology | Ramachandhran B.,Rice University | Pu H.,Rice University | Liu X.-J.,Swinburne University of Technology
Physical Review Letters | Year: 2012

We investigate theoretically the phase diagram of a spin-orbit coupled Bose gas in two-dimensional harmonic traps. We show that at strong spin-orbit coupling the single-particle spectrum decomposes into different manifolds separated by ω ⊥, where ω ⊥ is the trapping frequency. For a weakly interacting gas, quantum states with Skyrmion lattice patterns emerge spontaneously and preserve either parity symmetry or combined parity-time-reversal symmetry. These phases can be readily observed in a spin-orbit coupled gas of Rb87 atoms in a highly oblate trap. © 2012 American Physical Society.


Lee C.T.A.,Rice University | Morton D.M.,University of California at Riverside
Earth and Planetary Science Letters | Year: 2015

High silica (>70 wt.% SiO2) granites (HSGs) are important carriers of highly incompatible elements, thus, understanding their origin is relevant to understanding how the composition of the continental crust evolves. We examined a large-scale geochemical study of plutons in the Peninsular Ranges Batholith in southern California (USA) to better understand the petrogenetic relationships between HSGs and the batholith. Using highly incompatible and compatible elements, we show that HSGs represent residual liquids within a felsic (69-72 wt.% SiO2) magmatic crystal mush at crystal fractions of 50-60% and residual liquid fractions of 40-50%. Trace element systematics show that separation of the HSG liquid from the crystal mush is inefficient, such that no more than 70-80% of the HSG is fully extracted and the remaining greater than 20-30% remains trapped in cumulate mush. We find little evidence of more efficient liquid-crystal segregation, which suggests that compaction-induced segregation may be too slow to be important on a large scale. Instead, the terminal porosity of 20-30% coincides with theoretical maximum packing fraction of unimodal particles settled out of suspension (~0.74), which may indicate that crystal settling - perhaps in the form of hindered settling - drives segregation of viscous silicic melts and crystals. Unlike compaction, settling operates on timescales of 1-10 ky, fast enough to generate large volumes of HSG and complementary cumulates with trapped melt before magma chambers freeze. Many felsic plutons may thus be cumulates, but because of trapped melt, they are difficult to geochemically distinguish from plutons whose compositions fall along liquid lines of descent. The approach here, using a combination of highly incompatible and compatible elements, provides a way of identifying and quantifying trapped melt fractions. Finally, we show that HSGs appear to form only in the shallow crust (<10 km) and rarely in the middle to lower crust. Where HSGs are common, mafic magmas are common too, suggesting a genetic relationship between the two. If HSGs derive by crystal fractionation of basaltic parents, they represent at most 5% of the original mass of parental magma, but because they form almost exclusively at low pressures, they may be over-represented in shallowly exhumed batholiths. Why HSGs form primarily in the upper crust is unclear. © 2014 Elsevier B.V.


Yang L.H.,University of California at Davis | Rudolf V.H.W.,Rice University
Ecology Letters | Year: 2010

Climate change is altering the phenology of many species and the timing of their interactions with other species, but the impacts of these phenological shifts on species interactions remain unclear. Classical approaches to the study of phenology have typically documented changes in the timing of single life-history events, while phenological shifts affect many interactions over entire life histories. In this study, we suggest an approach that integrates the phenology and ontogeny of species interactions with a fitness landscape to provide a common mechanistic framework for investigating phenological shifts. We suggest that this ontogeny-phenology landscape provides a flexible method to document changes in the relative phenologies of interacting species, examine the causes of these phenological shifts, and estimate their consequences for interacting species. © 2009 Blackwell Publishing Ltd/CNRS.


Knez I.,Rice University | Du R.-R.,Rice University | Sullivan G.,Teledyne Scientific and Imaging
Physical Review Letters | Year: 2011

We present an experimental study of low temperature electronic transport in the hybridization gap of inverted InAs/GaSb composite quantum wells. An electrostatic gate is used to push the Fermi level into the gap regime, where the conductance as a function of sample length and width is measured. Our analysis shows strong evidence for the existence of helical edge modes proposed by Liu et al. Edge modes persist in spite of sizable bulk conduction and show only a weak magnetic field dependence-a direct consequence of a gap opening away from the zone center. © 2011 American Physical Society.


Hu H.,Swinburne University of Technology | Jiang L.,Rice University | Liu X.-J.,Swinburne University of Technology | Pu H.,Rice University
Physical Review Letters | Year: 2011

Motivated by the prospect of realizing a Fermi gas with a synthetic non-Abelian gauge field, we investigate theoretically a strongly interacting Fermi gas in the presence of a Rashba spin-orbit coupling. As the twofold spin degeneracy is lifted by spin-orbit interaction, bound pairs with mixed singlet and triplet components emerge, leading to an anisotropic superfluid. We calculate the relevant physical quantities, such as the momentum distribution, the single-particle spectral function, and the spin structure factor, that characterize the system. © 2011 American Physical Society.


Whitney K.D.,Rice University | Garland Jr. T.,University of California at Riverside
PLoS Genetics | Year: 2010

Mechanisms underlying the dramatic patterns of genome size variation across the tree of life remain mysterious. Effective population size (Ne) has been proposed as a major driver of genome size: selection is expected to efficiently weed out deleterious mutations increasing genome size in lineages with large (but not small) Ne. Strong support for this model was claimed from a comparative analysis of Neu and genome size for ≈30 phylogenetically diverse species ranging from bacteria to vertebrates, but analyses at that scale have so far failed to account for phylogenetic nonindependence of species. In our reanalysis, accounting for phylogenetic history substantially altered the perceived strength of the relationship between Neu and genomic attributes: there were no statistically significant associations between Neu and gene number, intron size, intron number, the half-life of gene duplicates, transposon number, transposons as a fraction of the genome, or overall genome size. We conclude that current datasets do not support the hypothesis of a mechanistic connection between Ne and these genomic attributes, and we suggest that further progress requires larger datasets, phylogenetic comparative methods, more robust estimators of genetic drift, and a multivariate approach that accounts for correlations between putative explanatory variables. © 2010 Whitney, Garland.


Ensor K.B.,Rice University | Raun L.H.,Rice University | Raun L.H.,City of Houston Health and Human Services
Circulation | Year: 2013

Background: Evidence of an association between the exposure to air pollution and overall cardiovascular morbidity and mortality is increasingly found in the literature. However, results from studies of the association between acute air pollution exposure and risk of out-of-hospital cardiac arrest (OHCA) are inconsistent for fine particulate matter, and, although pathophysiological evidence indicates a plausible link between OHCA and ozone, none has been reported. Approximately 300 000 persons in the United States experience an OHCA each year, of which >90% die. Understanding the association provides important information to protect public health. Methods and Results: The association between OHCA and air pollution concentrations hours and days before onset was assessed by using a time-stratified case-crossover design using 11 677 emergency medical service-logged OHCA events between 2004 and 2011 in Houston, Texas. Air pollution concentrations were obtained from an extensive area monitor network. An average increase of 6 μg/m3 in fine particulate matter 2 days before onset was associated with an increased risk of OHCA (1.046; 95% confidence interval, 1.012-1.082). A 20-ppb ozone increase for the 8-hour average daily maximum was associated with an increased risk of OHCA on the day of the event (1.039; 95% confidence interval, 1.005-1.073). Each 20-ppb increase in ozone in the previous 1 to 3 hours was associated with an increased risk of OHCA (1.044; 95% confidence interval, 1.004-1.085). Relative risk estimates were higher for men, blacks, or those aged >65 years. Conclusions: The findings confirm the link between OHCA and fine particulate matter and introduce evidence of a similar link with ozone. © 2013 American Heart Association, Inc.


Atala A.,Wake Forest Institute for Regenerative Medicine | Kurtis Kasper F.,Rice University | Mikos A.G.,Rice University
Science Translational Medicine | Year: 2012

Tissue engineering has emerged at the intersection of numerous disciplines to meet a global clinical need for technologies to promote the regeneration of functional living tissues and organs. The complexity of many tissues and organs, coupled with confounding factors that may be associated with the injury or disease underlying the need for repair, is a challenge to traditional engineering approaches. Biomaterials, cells, and other factors are needed to design these constructs, but not all tissues are created equal. Flat tissues (skin); tubular structures (urethra); hollow, nontubular, viscus organs (vagina); and complex solid organs (liver) all present unique challenges in tissue engineering. This review highlights advances in tissue engineering technologies to enable regeneration of complex tissues and organs and to discuss how such innovative, engineered tissues can affect the clinic.


Niemeier D.,University of California at Davis | Gombachika H.,University of Malawi | Richards-Kortum R.,Rice University
Science | Year: 2014

More of the world's population has access to cell phones than to basic sanitation facilities, a gap that can only be closed if the engineering and international aid communities adopt new approaches to design for scarcity and scalability.


Nguyen J.H.V.,Rice University | Dyke P.,Swinburne University of Technology | Luo D.,Rice University | Malomed B.A.,Tel Aviv University | Hulet R.G.,Rice University
Nature Physics | Year: 2014

Solitons are localized wave disturbances that propagate without changing shape, a result of a nonlinear interaction that compensates for wave packet dispersion. Individual solitons may collide, but a defining feature is that they pass through one another and emerge from the collision unaltered in shape, amplitude, or velocity, but with a new trajectory reflecting a discontinuous jump. This remarkable property is mathematically a consequence of the underlying integrability of the one-dimensional (1D) equations, such as the nonlinear Schrödinger equation, that describe solitons in a variety of wave contexts, including matter waves. Here we explore the nature of soliton collisions using Bose-Einstein condensates of atoms with attractive interactions confined to a quasi-1D waveguide. Using real-time imaging, we show that a collision between solitons is a complex event that differs markedly depending on the relative phase between the solitons. By controlling the strength of the nonlinearity we shed light on these fundamental features of soliton collisional dynamics, and explore the implications of collisions in the proximity of the crossover between one and three dimensions where the loss of integrability may precipitate catastrophic collapse. © 2014 Macmillan Publishers Limited. All rights reserved.


Patent
Privatran and Rice University | Date: 2011-09-08

Various embodiments of the present invention pertain to memresistor cells that comprise: (1) a substrate; (2) an electrical switch associated with the substrate; (3) an insulating layer; and (3) a resistive memory material. The resistive memory material is selected from the group consisting of SiO_(x), SiO_(x)H, SiO_(x)N_(y), SiO_(x)N_(y)H, SiO_(x)Cz, SiO_(x)C_(z)H, and combinations thereof, wherein each of x, y and z are equal or greater than 1 or equal or less than 2. Additional embodiments of the present invention pertain to memresistor arrays that comprise: (1) a plurality of bit lines; (2) a plurality of word lines orthogonal to the bit lines; and (3) a plurality of said memresistor cells positioned between the word lines and the bit lines. Further embodiments of the present invention provide methods of making said memresistor cells and arrays.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2010

PrivaTran proposes the use of newly-developed manufacturing methods that convert materials commonly found in conventional integrated circuit (IC) manufacturing into memristor devices with increased packing density and an advanced, three-dimensional (3D) architecture. The memristor devices can be formed in the interconnect layers of a conventional IC so that the area available for underlying transistors is not affected. This approach results in a 3D architecture achieved using a single substrate without the need for bonding multiple die together with flip-chip or through-silicon-via technologies. Furthermore, the memristor devices are much smaller than single transistors for any given technology node, and will scale to smaller dimensions as IC technology continues to progress towards smaller and smaller transistor sizes. The two-terminal memristor devices have numerous advantages including on/off conductance ratios greater than 104, reversible and fast switching, long retention times and immunity to current-induced degradation. In addition, their inherent simplicity makes them highly compatible with Si-based microelectronics technology, leading to a 3D architecture that can be readily transferred into semiconductor products at the most basic, integrated circuit level. BENEFIT: The memristor is of great interest to the Department of Defense (DoD) since it can potentially revolutionize numerous analog and digital circuit technologies. Specific Air Force applications that would benefit from this technology include tunable RF circuits in software defined radios, delta sigma modulators, and analog-to-digital converters (ADC). Furthermore, memristors can theoretically be used to simulate the human synapse, making them useful for non-Boolean, neuromorphic computing, which is an attractive computing technique due to its massive parallelism, scalability, and inherent fault-tolerance. Such neuromorphic computers could lead to game changing capabilities in managing and exploiting the global information grid, as well as enabling revolutionary advancements in cyber information processing and “cloud computing,” which requires an IT infrastructure of hundreds of thousands of servers and storage systems. The memristor can also be used for nonvolatile memory. Applications include radiation hardened devices for space-based surveillance platforms, launch vehicles and miniature kill vehicles for the MDA ballistic missile defense system; integrated sensor systems for imaging sensors used for automatic object identification and target recognition; friend or foe identification; and theater threat assessment. The DoD is aggressively developing robotic technologies for unmanned and totally autonomous air, ground, and sea vehicles which require a multitude of sensors and high-speed, high-density, low-power memories for obstacle detection, identification, and avoidance, as well as the recording, compression, decoding, and real time image processing of imaging sensor data.


As the use of nanoparticles becomes more prevalent, it is clear that human exposure will inevitably increase. Considering the rapidly ageing European population and the resulting increase in the incidence of neurodegenerative diseases, there is an urgent need to address the risk presented by nanoparticles towards neurodegenerative diseases. It is believed that nanoparticles can pass through the blood-brain barrier. Once in the brain, nanoparticles have two potential major effects. They can induce oxidative activity (production of Reactive Oxygen Species), and can induce anomalous protein aggregation behaviour (fibrillation). There are multiple disease targets for the nanoparticles, including all of the known fibrillation diseases (e.g. Alzheimers and Parkinsons diseases). The factors that determine which nanoparticles enter the brain are not known. Nanoparticle size, shape, rigidity and composition are considered important, and under physiological conditions, the nature of the adsorbed biomolecule corona (proteins, lipids etc.) determines the biological responses. The NeuroNano project will investigate the detailed mechanisms of nanoparticle passage through the blood-brain barrier using primary cell co-cultures and animal studies. Using nanoparticles that are shown to reach the brain, we will determine the mechanisms of ROS production and protein fibrillation, using state-of-the-art approaches such as redox proteomics and isolation/characterisation of the critical pre-fibrillar species. Animal models for Alzheimers diseases will confirm the effects of the nanoparticles in vivo. At all stages the exact nature of the nanoparticle biomolecule corona will be determined. The result will be a risk-assessment framework for assessing the safety of nanoparticles towards neurodegenerative diseases, based on the connection of their biological effects to their biomolecule corona, which determines the biological response in vivo and reports on the nanoparticles history.


News Article | February 15, 2017
Site: www.eurekalert.org

HOUSTON - (Feb. 15, 2017) - Five years of hard work and a little "cosmic luck" led Rice University researchers to a new method to obtain structural details on molecules in biomembranes. The method by the Rice lab of physicist Jason Hafner combines experimental and computational techniques and relies on the plasmonic properties of gold nanoparticles. It takes advantage of the nanoparticles' unique ability to focus light on very small targets. The researchers call their protocol SABERS, for structural analysis by enhanced Raman scattering, and say it could help scientists who study amyloid interactions implicated in neurodegenerative disease, the neuroprotective actions of fatty acids and the function of chemotherapy agents. The details appear this month in the American Chemical Society journal Nano Letters. Their method extracts the location of specific chemical groups within the molecules by locating their characteristic vibrations. When a laser activates plasmons in the nanoparticles, it amplifies vibrationally scattered light from nearby molecules, a phenomenon called surface-enhanced Raman scattering (SERS). The enhancement is sensitive to exactly where the molecule sits relative to the nanoparticle. "Molecules can vibrate in many different ways, so we have to assign a 'center of vibration' to each one," Hafner said. "If you watch some part of a molecule vibrating, you can visualize where it occurs, but we also had to find a mathematical way to describe it." SERS spectra are notoriously difficult to untangle, so the full SABERS method also requires unenhanced spectral measurements and theoretical calculations of both the nanorod optics and the molecular properties, he said. Hafner and his team tested their technique on three structures: surfactant molecules that come with gold nanorods, lipid molecules that form membranes on gold nanorods and tryptophan, an amino acid that settles into the membrane. "We found that the surfactant layer is tilted by 25 degrees, which is interesting because it explains why other measurements found that the layer appears thinner than expected," Hafner said. Lipids easily replace surfactants on nanorods since they end in the same chemical structure. By comparing vibrations of that structure in the lipid headgroup to a double bond in the tail, SABERS found the correct orientation and thickness of the lipid bilayer membrane. "It's just cosmic luck that a lipid ends in a perfectly symmetric structure that vibrates and is Raman active and loves to sit on a nanorod," Hafner said. The researchers also used SABERS to locate tryptophan in the lipid bilayer. "It's very bright, spectroscopically, and easy to see," he said. "In real biological structures, tryptophan is just a small residue attached to a much larger protein. However, tryptophan helps anchor the protein to the membrane, so researchers want to know where it prefers to sit." Next, Hafner wants to analyze bigger molecules. "In principle, through spectroscopic tricks, we could take this to larger structures, and perhaps even find every residue in a protein to get the whole structure. That's futuristic, but it's where we think we can go with it," he said. Rice alumnus James Matthews, now a software engineer at Schlumberger, is lead author of the paper. Co-authors are Rice undergraduate students Cyna Shirazinejad and Grace Isakson and graduate student Steven Demers. Hafner is a professor of physics and astronomy and of chemistry. The Robert A. Welch Foundation and Lockheed Martin supported the research. This news release can be found online at http://news. The molecules tryptophan, left, and decyltrimethylammonium bromide, right, over their SABERS maps. SABERS, a new analysis method developed at Rice University, is able to obtain structural details of molecules in lipid membranes near gold nanoparticles without molecular tags. (Credit: Hafner Lab/Rice University) Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | February 18, 2017
Site: news.yahoo.com

Former U.S. President Abraham Lincoln's statue at the Lincoln Memorial is seen in Washington March 27, 2015. REUTERS/Gary Cameron (Reuters) - Abraham Lincoln, George Washington and Franklin D. Roosevelt were ranked as the top three U.S. presidents in history respectively while Barack Obama entered the rankings in the 12th spot, based on a survey of historians released on Friday. Theodore Roosevelt and Dwight Eisenhower rounded out the top five of 43 presidents in U.S. history, a survey of historians' rankings of presidential leadership found. It was the third such survey released by the C-SPAN television network ahead of the Presidents Day weekend. "Once again the big three are Lincoln, Washington and FDR - as it should be. That Obama came in at number 12 his first time out is quite impressive," said Douglas Brinkley, a history professor at Rice University, in a statement by C-SPAN. The survey, which was held twice before in 2000 and 2009, asked 91 presidential historians to rank the 43 former presidents based on 10 attributes of leadership. Obama, who left office in January with favorable approval ratings after serving eight years, was ranked third in the "pursued equal justice of all" category and 39th in the "relations with congress" category. "One would have thought that former President Obama’s favorable rating when he left office would have translated into a higher ranking," said Edna Greene Medford, a history professor at Howard University. "But, of course, historians prefer to view the past from a distance, and only time will reveal his legacy." Andrew Johnson, Franklin Pierce and James Buchanan were ranked as the worst presidents in U.S. history, even lower than William Henry Harrison, who served for only one month.


HOUSTON, March 02, 2017 (GLOBE NEWSWIRE) -- On February 22, 2017, the board of directors (the “Board”) of Targa Resources Corp. (NYSE:TRGP) ("Targa" or the "Company") appointed Robert Muraro as Executive Vice President – Commercial of the Company, effective February 22, 2017.  Mr. Muraro joined Targa in August 2004 as a Director of Business Development and has since served in roles of increasing responsibility, most recently as Senior Vice President of Commercial and Business Development. Prior to joining Targa, Mr. Muraro was with ABN Amro in their energy investment banking group.  He holds a Bachelor of Arts Degree from Rice University. Targa Resources Corp. is a leading provider of midstream services and is one of the largest independent midstream energy companies in North America. Targa owns, operates, acquires, and develops a diversified portfolio of complementary midstream energy assets. The Company is primarily engaged in the business of: gathering, compressing, treating, processing, and selling natural gas; storing, fractionating, treating, transporting, and selling NGLs and NGL products, including services to LPG exporters; gathering, storing, and terminaling crude oil; storing, terminaling, and selling refined petroleum products. The principal executive offices of Targa are located at 1000 Louisiana, Suite 4300, Houston, TX 77002 and their telephone number is 713-584-1000.  For more information please go to www.targaresources.com.


DETROIT, MI--(Marketwired - February 13, 2017) - SmithGroupJJR, one of the nation's leading architecture, engineering and planning firms, is pleased to announce that Tom Butcavage, Sam D'Amico, Mark Kranz and David Varner have been elevated to the American Institute of Architects (AIA) College of Fellows. The recognition reflects their significant contributions to architecture and society and achievement of a standard of excellence in the profession. The four from SmithGroupJJR will be among the 178 new Fellows recognized at an investiture ceremony at the AIA Conference on Architecture 2017, to be held April 27-29 in Orlando, Florida. Tom Butcavage, FAIA, LEED AP BD+C, is a SmithGroupJJR vice president and leader of the Higher Education Studio at the firm's Washington, DC office. He has spent the past 20 years as a pioneer in the programming, planning and design of award-winning and nationally significant higher education facilities across the U.S., ranging from instructional facilities and student centers to libraries and professional schools. Butcavage is widely recognized for his unparalleled expertise in law school design. He has led more than 20 law school projects, each containing a variety of spaces for specialized instruction, research and legal skills development. Among his most recently completed law schools are the University of Utah S.J. Quinney College of Law, American University Washington College of Law, George State University College of Law, and New York Law School - all which exemplify cutting-edge environments for modern legal education. Presently, he is leading the design of a number of new professional education facilities at the University of South Carolina, University of North Carolina at Chapel Hill, and Georgetown University. A frequent presenter at national academic conferences such as the Society for College and University Planning, American Bar Association and Association of College Unions International, Butcavage speaks on topics including the design of student spaces and maximizing student engagement through new facilities. He has served as a critic and lecturer at the Corcoran College of Art + Design and Catholic University of America School of Architecture and Planning. Butcavage is a graduate of Columbia University with a Master of Architecture, preceded by a BA in art history at Swarthmore College. His is a resident of Washington, DC's Shepherd Park neighborhood. Sam D'Amico, FAIA, LEED AP BD+C, is a SmithGroupJJR vice president and design leader for the firm's Health Practice. Based at its San Francisco office, he is now commencing his 35th year practicing architecture throughout the U.S. as well as parts of Asia. D'Amico approaches every project with a specific architectural response that integrates the client's culture, context and place. His design tenets include the integration of daylight, nature and art into the healthcare environment to improve the healing process. D'Amico has designed for world-class teaching institutions and national leaders in healthcare such as the University of California San Francisco Medical Center, Kaiser Permanente, and Barnes Jewish Hospital. Currently, D'Amico is design principal for a new medical office building and bed tower, part of a multi-year expansion program for Community Regional Medical Center in Fresno, California. His design of the new Robley Rex Veteran Administration Medical Center, a 1.2 million-square-foot replacement hospital to be constructed in Louisville, Kentucky, led to SmithGroupJJR's award of a prestigious AIA Academy of Architecture National Health Design Award, Unbuilt Category. Another D'Amico design, for the Fuwai Huazhong Cardiovascular and Heart Hospital, Zhenghou, Henan Province, China, was the recipient of an AIA San Francisco Citation Award for unbuilt design. At SmithGroupJJR, D'Amico is a member of the firm's National Design Committee. In 2016, he served as a featured panelist at firm's public forum on design, Perspectives, for a program titled, "The Fusion of Art and Architecture." A graduate from the University of Houston with a Bachelor of Architecture with Honors, the Houston, Texas native now resides in Lafayette, California, where he is on the Board of the city's Improvement Association. Mark Kranz, FAIA, LEED AP BD+C, vice president and design director at SmithGroupJJR, is known for his elegant and synthesized solutions for research and higher education environments across the U.S. As the designer of projects recognized by a total of 27 AIA design awards to-date, he believes that each has the potential for excellence, regardless of budget or constraints. Kranz, who is based at the firm's Phoenix office, is an advocate of pushing the boundaries of innovation and sustainability. He designed the LEED Platinum Energy Systems Integration Facility at the National Renewable Energy Lab in Golden, Colorado, leading a complex team and design vision for a high performance/ultra-low energy building later honored as R&D Magazine's "Lab of the Year." His design of the Defense POW/MIA Accounting Agency Center for Excellence, located at Joint Base Pearl Harbor Hickam, Oahu, Hawaii, was the recipient of the Naval Facilities Engineering Command (NAVFAC) 2015 Commander's Award for Design Excellence. Among Kranz's projects currently underway is the $82 million Engineering Building, now under construction at the University of Texas at Dallas. Scheduled for completion in 2018, the new, 208,000-square-foot building will house the university's rapidly growing mechanical engineering program. He is also serving design principal for the new $60 million San Diego County Crime Laboratory, slated to be completed in 2019. Kranz was elected to the SmithGroupJJR Board of Directors in 2015 and is a member of the firm's National Design Committee and Science & Technology Practice. He is a graduate of the University of Nebraska in Lincoln with a Bachelor of Science in architectural studies, followed by a Master of Architecture from Arizona State University. He now resides in Phoenix. David Varner, FAIA, LEED AP BD+C, is vice president and director of the firm's 200-person office in Washington, DC, located in the 1700 New York Avenue building in the heart of DC's monumental core. Varner is known for his talent in discovering and celebrating hidden environmental, economic and design opportunities in existing buildings. His special expertise and success in creating new value for owners, communities and cities through such building transformation is well demonstrated with the complete transformation of the 2.1 million-square-foot, Constitution Center, a repositioning of a 1960's property into the largest, privately-owned office building in Washington, DC. Certified LEED Gold, the building today is not only highly energy-efficient, but secure, elegant and fully leased. Varner is currently serving as SmithGroupJJR's principal-in-charge for one of the District's most exciting new buildings now under construction: the $60 million, 150,000-square-foot, DC Water Headquarters. When completed in late 2017 along the waterfront of the Anacostia River, the new building will set a new standard for low-energy, high-performance and resilient waterfront development. As a result of his expertise in existing buildings, transformation, planning and mixed-use development, Varner is frequently invited to join interdisciplinary panels of some of the nation's most significant leadership groups. In 2015 he was elected a Trustee of the Federal City Council, a position that catalyzes the collaboration of key business leaders in Washington, DC to solve challenging problems across the city. He is a long-time member of the Urban Land Institute and currently on its exclusive Redevelopment and Reuse Council. Varner has been a member of the SmithGroupJJR Board of Directors since 2011. He is graduate of Rice University with dual degrees: a Bachelor of Arts degree in architecture and art/art history and a Bachelor of Architecture. A native of Houston, Texas, Varner now lives in Arlington, Virginia. The American Institute of Architects Fellowship program was developed to elevate those architects who have made a significant contribution to architecture and society and who have achieved a standard of excellence in the profession. Election to fellowship not only recognizes the achievements of architects as individuals, but also their significant contribution to architecture and society on a national level. SmithGroupJJR (www.smithgroupjjr.com) is an integrated architecture, engineering and planning firm, employing more than 1,100 across 10 offices. In May 2016, SmithGroupJJR was ranked as one of the nation's top architecture firms by Architect magazine's Architect 50. A national leader in sustainable design, SmithGroupJJR has 420 LEED professionals and 160 LEED certified projects.


News Article | February 17, 2017
Site: www.cemag.us

Five years of hard work and a little “cosmic luck” led Rice University researchers to a new method to obtain structural details on molecules in biomembranes. The method by the Rice lab of physicist Jason Hafner combines experimental and computational techniques and relies on the plasmonic properties of gold nanoparticles. It takes advantage of the nanoparticles’ unique ability to focus light on very small targets. The researchers call their protocol SABERS, for structural analysis by enhanced Raman scattering, and say it could help scientists who study amyloid interactions implicated in neurodegenerative disease, the neuroprotective actions of fatty acids and the function of chemotherapy agents. The details appear this month in the American Chemical Society journal Nano Letters. Their method extracts the location of specific chemical groups within the molecules by locating their characteristic vibrations. When a laser activates plasmons in the nanoparticles, it amplifies vibrationally scattered light from nearby molecules, a phenomenon called surface-enhanced Raman scattering (SERS). The enhancement is sensitive to exactly where the molecule sits relative to the nanoparticle. “Molecules can vibrate in many different ways, so we have to assign a ‘center of vibration’ to each one,” Hafner says. “If you watch some part of a molecule vibrating, you can visualize where it occurs, but we also had to find a mathematical way to describe it.” SERS spectra are notoriously difficult to untangle, so the full SABERS method also requires unenhanced spectral measurements and theoretical calculations of both the nanorod optics and the molecular properties, he said. Hafner and his team tested their technique on three structures: surfactant molecules that come with gold nanorods, lipid molecules that form membranes on gold nanorods and tryptophan, an amino acid that settles into the membrane. “We found that the surfactant layer is tilted by 25 degrees, which is interesting because it explains why other measurements found that the layer appears thinner than expected,” Hafner says. Lipids easily replace surfactants on nanorods since they end in the same chemical structure. By comparing vibrations of that structure in the lipid headgroup to a double bond in the tail, SABERS found the correct orientation and thickness of the lipid bilayer membrane. “It’s just cosmic luck that a lipid ends in a perfectly symmetric structure that vibrates and is Raman active and loves to sit on a nanorod,” Hafner says. The researchers also used SABERS to locate tryptophan in the lipid bilayer. “It’s very bright, spectroscopically, and easy to see,” he says. “In real biological structures, tryptophan is just a small residue attached to a much larger protein. However, tryptophan helps anchor the protein to the membrane, so researchers want to know where it prefers to sit.” Next, Hafner wants to analyze bigger molecules. “In principle, through spectroscopic tricks, we could take this to larger structures, and perhaps even find every residue in a protein to get the whole structure. That’s futuristic, but it’s where we think we can go with it,” he says. Rice alumnus James Matthews, now a software engineer at Schlumberger, is lead author of the paper. Co-authors are Rice undergraduate students Cyna Shirazinejad and Grace Isakson and graduate student Steven Demers. Hafner is a professor of physics and astronomy and of chemistry. The Robert A. Welch Foundation and Lockheed Martin supported the research.


News Article | February 8, 2017
Site: www.medicalnewstoday.com

Chemists scouring Appalachia for exotic microorganisms that could yield blockbuster drugs have reported a unique find from the smoldering remains of a coal mine fire that's burned for nearly a decade in southeastern Kentucky. In new findings this week in the journal Nature Chemical Biology, a research team from Rice University, the University of Kentucky and the University of Oklahoma made new - and in some cases more effective - versions of the antibiotic daptomycin using an enzyme from a soil bacterium found in smoke vents of the Ruth Mullins coal fire. "We don't know the mechanism for why it makes daptomycin work better," said Rice structural biologist George Phillips, whose team determined the three-dimensional structure of the enzyme. "It may be that it just gets into membranes better because the enzyme's specialty is adding a prenyl group, an organic molecule that typically comes into play when a molecule docks with the outer membrane of a cell. The target for the drug is associated with the membrane, so this might be the mechanism for the improvement." The study's authors said the prenylating enzyme, which is called PriB, could prove useful to drug companies. Study co-author Jon Thorson, director of the University of Kentucky's Center for Pharmaceutical Research and Innovation (CPRI), said, "A major focus of CPRI is the discovery of novel microbial natural products and corresponding biocatalysts that have synthetic applications. The PriB discovery represents an example of the latter and, unlike most permissive prenyltransferases that can modify simple molecules, PriB is one of the first capable of modifying highly complex drugs like daptomycin." Thorson's center specializes in "bioprospecting," the search for new organisms like the one that yielded the prenylating enzyme, as well as the follow-up laboratory studies on the organisms to uncover and exploit new biosynthetic pathways, enzyme mechanisms, ligation chemistries and other biochemistry that could be useful for making drugs. Since the center's founding five years ago, Thorson and colleagues have isolated more than 750 microbial strains, including some that live miles below ground in coal mines. In addition, the team has isolated more than 250 corresponding microbial metabolites, more than half of which have never been previously documented. The organism that yielded PriB is Streptomyces species "RM-5-8," where RM reflects the strain's point of origin -- the Ruth Mullins coal fire, which has burned in eastern Kentucky for almost a decade. "Biological activities of prenylated compounds encompass virtually all fields of pharmacological sciences, hence prenylation of drugs is a novel way of creating new drug leads," said study co-author Shanteri Singh, an assistant professor at the University of Oklahoma whose research focuses on understanding and exploiting prenylating enzymes. "In addition, developing an enzymatic prenylation platform is an interesting alternative, especially for molecules such as daptomycin, which is chemically challenging to modify." Phillips, Rice's Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology and professor of chemistry, has collaborated closely with both Thorson and Singh for more than a decade. Phillips' team specializes in using X-ray crystallography to determine the precise structure of proteins like PriB. "In the organism, the enzyme both makes prenyl groups and attaches them to the standard amino acid tryptophan," Phillips said. "This is part of a much larger metabolic pathway, but the (University of Kentucky) team isolated the gene that produces the enzyme, and they used that to create a form of E. coli that produced the enzyme in bulk." Phillips' team crystallized the protein and determined its shape. Phillips said the enzyme has a pocket where it binds with tryptophan and attaches the prenyl group. Studies at the University of Kentucky found the enzyme readily prenylates more than a dozen other compounds and can also use "nonnative" prenyl donors that notably expand its synthetic utility. Phillips said his group is already looking for ways to modify PriB's pocket to make it even more useful in biosynthesis. "This prenylation reaction could be broadly useful in producing drugs and other chemicals through biotechnology," Phillips said. "Because the enzyme is permissive, it is possible to think of using it to produce all sorts of drugs, including antibiotics and anti-cancer therapies." Further information can be viewed at https://youtu.be/VglEEjMviVA


News Article | February 15, 2017
Site: www.prweb.com

NDA Partners Chairman Carl Peck, MD, announced today that Deborah Wenkert, MD a former Clinical Research Medical Director at Amgen and pediatrics, rheumatology, and bone disease expert has joined the company as an Expert Consultant. Following an immunology postdoc at Harvard University, Dr. Wenkert was an instructor at Washington University School of Medicine and then, for eleven years, an Adjunct Assistant/Associate Clinical Professor at St Louis University School of Medicine in the division of rheumatology. Concurrent with her position at St. Louis University, Dr. Wenkert conducted research in adult and pediatric metabolic bone and genetic disorders and provided care to affected children as the Associate Director of the Center for Metabolic Bone Disease and Molecular Research at Shriners Hospital for Children, St Louis. “Dr. Deborah Wenkert’s knowledge and expertise in adult and pediatric metabolic bone and genetic disorders, in addition to, her extensive experience in pediatric rheumatology and pediatric clinical trials will provide an excellent resource to our clients and to our growing Pediatric Practice,” said Dr. Peck. “We are very pleased to welcome her to NDA Partners.” Dr. Wenkert earned her MD from the University of Texas Medical Branch (Galveston, Texas), attended graduate school at Baylor College of Medicine Graduate School, and obtained a BA in Biochemistry from Rice University. She is board certified in pediatrics and pediatric rheumatology, a member of the American Society for Bone and Mineral Research, and a Fellow of the American Academy of Pediatrics and American College of Rheumatology. About NDA Partners NDA Partners is a strategy consulting firm specializing in expert product development and regulatory advice to the medical products industry and associated service industries such as law firms, investment funds and government research agencies. The highly experienced Principals and Premier Experts of NDA Partners include three former FDA Center Directors; the former Chairman of the Medicines and Healthcare Products Regulatory Agency (MHRA) in the UK; an international team of more than 100 former pharmaceutical industry and regulatory agency senior executives; and an extensive roster of highly proficient experts in specialized areas including nonclinical development, toxicology, pharmacokinetics, CMC, medical device design control and quality systems, clinical development, regulatory submissions, and development program management. Services include product development and regulatory strategy, expert consulting, high-impact project teams, and virtual product development teams.


News Article | February 15, 2017
Site: www.eurekalert.org

Understanding how oil and gas molecules, water and rocks interact at the nanoscale will help make extraction of hydrocarbons through hydraulic fracturing more efficient, according to Rice University researchers. Rice engineers George Hirasaki and Walter Chapman are leading an effort to better characterize the contents of organic shale by combining standard nuclear magnetic resonance (NMR) -- the same technology used by hospitals to see inside human bodies - with molecular dynamics simulations. The work presented this month in the Journal of Magnetic Resonance details their method to analyze shale samples and validate simulations that may help producers determine how much oil and/or gas exist in a formation and how difficult they may be to extract. Oil and gas drillers use NMR to characterize rock they believe contains hydrocarbons. NMR manipulates the hydrogen atoms' nuclear magnetic moments, which can be forced to align by an applied external magnetic field. After the moments are perturbed by radio-frequency electromagnetic pulses, they "relax" back to their original orientation, and NMR can detect that. Because relaxation times differ depending on the molecule and its environment, the information gathered by NMR can help identify whether a molecule is gas, oil or water and the critical size of the pores that contain them. "This is their eyes and ears for knowing what's down there," said Hirasaki, who said NMR instruments are among several tools in the string sent downhole to "log," or gather information, about a well. In conventional reservoirs, he said, the NMR log can distinguish gas, oil and water and quantify the amounts of each contained in the pores of the rock from their relaxation times -- known as T1 and T2 -- as well as how diffuse fluids are. "If the rock is water-wet, then oil will relax at rates close to that of bulk oil, while water will have a surface-relaxation time that is a function of the pore size," Hirasaki said. "This is because water is relaxed by sites at the water/mineral interface and the ratio of the mineral surface area to water volume is larger in smaller pores. The diffusivity is inversely proportional to the viscosity of the fluid. Thus gas is easily distinguished from oil and water by measuring diffusivity simultaneously with the T2 relaxation time. "In unconventional reservoirs, both T1 and T2 relaxation times of water and oil are short and have considerable overlap," he said. "Also the T1/T2 ratio can become very large in the smallest pores. The diffusivity is restricted by the nanometer-to-micron size of the pores. Thus it is a challenge to determine if the signal is from gas, oil or water." Hirasaki said there is debate on whether the short relaxation times in shale are due to paramagnetic sites on mineral surfaces and asphaltene aggregates and/or due to the restricted motion of the molecules confined in small pores. "We don't have an answer yet, but this study is the first step," he said. "The development of technology to drill horizontal wells and apply multiple hydraulic fractures (up to about 50) is what made oil and gas production commercially viable from unconventional resources," Hirasaki said. "These resources were previously known as the 'source rock,' from which oil and gas found in conventional reservoirs had originated and migrated. The source rock was too tight for commercial production using conventional technology." Fluids pumped downhole to fracture a horizontal well contain water, chemicals and sand that keeps the fracture "propped" open after the injection stops. The fluids are then pumped out to make room for the hydrocarbons to flow. But not all the water sent downhole comes back. Often the chemical composition of the organic component of shale known as kerogen has an affinity that allows water molecules to bind and block the nanoscale pores that would otherwise let oil and gas molecules through. "Kerogen is the organic material that resisted biodegradation during deep burial," Hirasaki said. "When it gets to a certain temperature, the molecules start cracking and make hydrocarbon liquids. Higher temperature makes methane (natural gas). But the fluids are in pores that are so tight the technology developed for conventional reservoirs doesn't apply anymore." The Rice project managed by lead author Philip Singer, a research scientist in Hirasaki's lab, and co-author Dilip Asthagiri, a research scientist in Chapman's lab, a lecturer and director of Rice's Professional Master's in Chemical Engineering program, applies NMR to kerogen samples and compares it to computer models that simulate how the substances interact, particularly in terms of material's wettability, its affinity for binding to water, gas or oil molecules. "NMR is very sensitive to fluid-surface interactions," Singer said. "With shale, the complication we're dealing with is the nanoscale pores. The NMR signal changes dramatically compared with measuring conventional rocks, in which pores are larger than a micron. So to understand what the NMR is telling us in shale, we need to simulate the interactions down to the nanoscale." The simulations mimic the molecules' known relaxation properties and reveal how they move in such a restrictive environment. When matched with NMR signals, they help interpret conditions downhole. That knowledge could also lead to fracking fluids that are less likely to bind to the rock, improving the flow of hydrocarbons, Hirasaki said. "If we can verify with measurements in the laboratory how fluids in highly confined or viscous systems behave, then we'll be able to use the same types of models to describe what's happening in the reservoir itself," he said. One goal is to incorporate the simulations into iSAFT -- inhomogeneous Statistical Associating Fluid Theory -- a pioneering method developed by Chapman and his group to simulate the free energy landscapes of complex materials and analyze their microstructures, surface forces, wettability and morphological transitions. "Our results challenge approximations in models that have been used for over 50 years to interpret NMR and MRI (magnetic resonance imaging) data," Chapman said. "Now that we have established the approach, we hope to explain results that have baffled scientists for years." Chapman is the William W. Akers Professor of Chemical and Biomolecular Engineering and associate dean for energy in the George R. Brown School of Engineering. Hirasaki is the A.J. Hartsook Professor Emeritus of Chemical and Biomolecular Engineering. The Rice University Consortium on Processes in Porous Media supported the research, with computing resources supplied by the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy, and the Texas Advanced Computing Center at the University of Texas at Austin. This news release can be found online at http://news. Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


Home > Press > Good vibrations help reveal molecular details: Rice University scientists combine disciplines to pinpoint small structures in unlabeled molecules Abstract: Five years of hard work and a little "cosmic luck" led Rice University researchers to a new method to obtain structural details on molecules in biomembranes. The method by the Rice lab of physicist Jason Hafner combines experimental and computational techniques and relies on the plasmonic properties of gold nanoparticles. It takes advantage of the nanoparticles' unique ability to focus light on very small targets. The researchers call their protocol SABERS, for structural analysis by enhanced Raman scattering, and say it could help scientists who study amyloid interactions implicated in neurodegenerative disease, the neuroprotective actions of fatty acids and the function of chemotherapy agents. The details appear this month in the American Chemical Society journal Nano Letters. Their method extracts the location of specific chemical groups within the molecules by locating their characteristic vibrations. When a laser activates plasmons in the nanoparticles, it amplifies vibrationally scattered light from nearby molecules, a phenomenon called surface-enhanced Raman scattering (SERS). The enhancement is sensitive to exactly where the molecule sits relative to the nanoparticle. "Molecules can vibrate in many different ways, so we have to assign a 'center of vibration' to each one," Hafner said. "If you watch some part of a molecule vibrating, you can visualize where it occurs, but we also had to find a mathematical way to describe it." SERS spectra are notoriously difficult to untangle, so the full SABERS method also requires unenhanced spectral measurements and theoretical calculations of both the nanorod optics and the molecular properties, he said. Hafner and his team tested their technique on three structures: surfactant molecules that come with gold nanorods, lipid molecules that form membranes on gold nanorods and tryptophan, an amino acid that settles into the membrane. "We found that the surfactant layer is tilted by 25 degrees, which is interesting because it explains why other measurements found that the layer appears thinner than expected," Hafner said. Lipids easily replace surfactants on nanorods since they end in the same chemical structure. By comparing vibrations of that structure in the lipid headgroup to a double bond in the tail, SABERS found the correct orientation and thickness of the lipid bilayer membrane. "It's just cosmic luck that a lipid ends in a perfectly symmetric structure that vibrates and is Raman active and loves to sit on a nanorod," Hafner said. The researchers also used SABERS to locate tryptophan in the lipid bilayer. "It's very bright, spectroscopically, and easy to see," he said. "In real biological structures, tryptophan is just a small residue attached to a much larger protein. However, tryptophan helps anchor the protein to the membrane, so researchers want to know where it prefers to sit." Next, Hafner wants to analyze bigger molecules. "In principle, through spectroscopic tricks, we could take this to larger structures, and perhaps even find every residue in a protein to get the whole structure. That's futuristic, but it's where we think we can go with it," he said. Rice alumnus James Matthews, now a software engineer at Schlumberger, is lead author of the paper. Co-authors are Rice undergraduate students Cyna Shirazinejad and Grace Isakson and graduate student Steven Demers. Hafner is a professor of physics and astronomy and of chemistry. The Robert A. Welch Foundation and Lockheed Martin supported the research. About Rice University Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to http://tinyurl.com/RiceUniversityoverview . Follow Rice News and Media Relations via Twitter @RiceUNews For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Yu R.,Renmin University of China | Yu R.,Shanghai JiaoTong University | Si Q.,Rice University
Physical Review Letters | Year: 2015

Motivated by the properties of the iron chalcogenides, we study the phase diagram of a generalized Heisenberg model with frustrated bilinear-biquadratic interactions on a square lattice. We identify zero-temperature phases with antiferroquadrupolar and Ising-nematic orders. The effects of quantum fluctuations and interlayer couplings are analyzed. We propose the Ising-nematic order as underlying the structural phase transition observed in the normal state of FeSe, and discuss the role of the Goldstone modes of the antiferroquadrupolar order for the dipolar magnetic fluctuations in this system. Our results provide a considerably broadened perspective on the overall magnetic phase diagram of the iron chalcogenides and pnictides, and are amenable to tests by new experiments. © 2015 American Physical Society.


Teperik T.V.,University Paris - Sud | Nordlander P.,Rice University | Aizpurua J.,Donostia International Physics Center | Borisov A.G.,University Paris - Sud
Physical Review Letters | Year: 2013

We present the optical response of two interacting metallic nanowires calculated for separation distances down to angstrom range. State-of-the-art local and nonlocal approaches are compared with full quantum time-dependent density functional theory calculations that give an exact account of nonlocal and tunneling effects. We find that the quantum results are equivalent to those from classical approaches when the nanoparticle separation is defined as the separation between centroids of the screening charges. This establishes a universal plasmon ruler for subnanometric distances. Such a ruler not only impacts the basis of many applications of plasmonics, but also provides a robust rule for subnanometric metrology. © 2013 American Physical Society.


Boppart S.A.,University of Illinois at Urbana - Champaign | Richards-Kortum R.,Rice University
Science Translational Medicine | Year: 2014

Leveraging advances in consumer electronics and wireless telecommunications, low-cost, portable optical imaging devices have the potential to improve screening and detection of disease at the point of care in primary health care settings in both low- and high-resource countries. Similarly, real-time optical imaging technologies can improve diagnosis and treatment at the point of procedure by circumventing the need for biopsy and analysis by expert pathologists, who are scarce in developing countries. Although many optical imaging technologies have been translated from bench to bedside, industry support is needed to commercialize and broadly disseminate these from the patient level to the population level to transform the standard of care. This review provides an overview of promising optical imaging technologies, the infrastructure needed to integrate them into widespread clinical use, and the challenges that must be addressed to harness the potential of these technologies to improve health care systems around the world. © 2014, American Association for the Advancement of Science. All rights reserved.


Rodriguez-Guzman R.,Rice University | Robledo L.M.,Autonomous University of Madrid
Physical Review C - Nuclear Physics | Year: 2014

The most recent parametrizations D1S, D1N, and D1M of the Gogny energy density functional are used to describe fission in the isotopes 232-280U. Fission paths, collective masses, and zero-point quantum corrections, obtained within the constrained Hartree-Fock-Bogoliubov approximation, are used to compute the systematics of the spontaneous fission half-lives tSF, the masses and charges of the fission fragments, and their intrinsic shapes. The Gogny-D1M parametrization has been benchmarked against available experimental data on inner and second barrier heights, excitation energies of the fission isomers, and half-lives in a selected set of Pu, Cm, Cf, Fm, No, Rf, Sg, Hs, and Fl nuclei. It is concluded that D1M represents a reasonable starting point to describe fission in heavy and superheavy nuclei. Special attention is also paid to understand the uncertainties in the predicted tSF values arising from the different building blocks entering the standard semiclassical Wentzel-Kramers-Brillouin formula. Although the uncertainties are large, the trend with mass or neutron numbers are well reproduced and therefore the theory still has predictive power. In this respect, it is also shown that modifications of a few percent in the pairing strength can have a significant impact on the collective masses leading to uncertainties in the tSF values of several orders of magnitude. © 2014 American Physical Society.


Esteban R.,Donostia International Physics Center | Borisov A.G.,University Paris - Sud | Nordlander P.,Rice University | Aizpurua J.,Donostia International Physics Center
Nature Communications | Year: 2012

Electromagnetic coupling between plasmonic resonances in metallic nanoparticles allows for engineering of the optical response and generation of strong localized near-fields. Classical electrodynamics fails to describe this coupling across sub-nanometer gaps, where quantum effects become important owing to non-local screening and the spill-out of electrons. However, full quantum simulations are not presently feasible for realistically sized systems. Here we present a novel approach, the quantum-corrected model (QCM), that incorporates quantum-mechanical effects within a classical electrodynamic framework. The QCM approach models the junction between adjacent nanoparticles by means of a local dielectric response that includes electron tunnelling and tunnelling resistivity at the gap and can be integrated within a classical electrodynamical description of large and complex structures. The QCM predicts optical properties in excellent agreement with fully quantum mechanical calculations for small interacting systems, opening a new venue for addressing quantum effects in realistic plasmonic systems. © 2012 Macmillan Publishers Limited. All rights reserved.


Wen Z.,Shanghai JiaoTong University | Yin W.,Rice University
Mathematical Programming | Year: 2013

Minimization with orthogonality constraints (e.g.; XT X = I) and/or spherical constraints (e.g.; ||x||2 = 1) has wide applications in polynomial optimization, combinatorial optimization, eigenvalue problems, sparse PCA, p-harmonic flows, 1-bit compressive sensing, matrix rank minimization, etc. These problems are difficult because the constraints are not only non-convex but numerically expensive to preserve during iterations. To deal with these difficulties, we apply the Cayley transform - a Crank-Nicolson-like update scheme - to preserve the constraints and based on it, develop curvilinear search algorithms with lower flops compared to those based on projections and geodesics. The efficiency of the proposed algorithms is demonstrated on a variety of test problems. In particular, for the maxcut problem, it exactly solves a decomposition formulation for the SDP relaxation. For polynomial optimization, nearest correlation matrix estimation and extreme eigenvalue problems, the proposed algorithms run very fast and return solutions no worse than those from their state-of-the-art algorithms. For the quadratic assignment problem, a gap 0.842 % to the best known solution on the largest problem "tai256c" in QAPLIB can be reached in 5 min on a typical laptop. © 2012 Springer and Mathematical Optimization Society.


News Article | February 16, 2017
Site: www.prweb.com

(Jan. 31, 2017) – CM First Group was recognized as one of the 10 Most Promising I.T. and Web Technology Companies at the Rice Alliance for Technology and Entrepreneurship 14th annual I.T. and Web Venture Forum in Houston on January 19, 2017. Forty Information Technology ventures showcased their companies at the largest venture capital conference in the Southwest with 300 attendees — including nearly 100 venture capitalists and other investors, over 200 entrepreneurs, along with industry representatives, business leaders, and service providers. The one-day event culminated in the announcement of the 10 I.T. and Web Technology Companies, chosen from 40 presenters and judged by investors and business leaders in attendance, based on the companies’ business plan presentations and investor feedback. Rice Alliance Managing Director Brad Burke announced the winners of the I.T. and Web Technology Company awards at the event. “Every year the quality of companies improves,” Burke said, “This year we had a diversity of companies including learning solutions and digital commerce platform. Company presenters at Rice Alliance venture forums and Rice Business Plan Competition have raised in excess of $4.2 billion. This year’s crop of winners is expected to achieve similar results.” “CM First was honored to attend the Forum along with other key industry leaders,” said CTO & Managing Director John Rhodes, “We feel fortunate to have been recognized by Rice Alliance for our innovative modernization technology, customized expertise, and dedicated service to the needs of our clients.” Sponsors of this year’s IT and Web Venture Forum included: Mercury Fund, Golden Section Technology, Vinson and Elkins LLP, Data Foundry, Pillsbury, Comcast Business, PKF, Norton Rose Fulbright, Winstead, Houston Angel Network, Station Houston, Central Texas Angel Network, Houston Technology Center, RedHouse Associates, Tech Wildcatters, Start and Teakwood Capital. Headquartered in Austin, Texas, CM First Group empowers organizations and system integrators with IBM mainframe and midrange applications to advance their code into the new digital economy. CM First has served the IBM i and IBM z community since 1999, and focuses on custom applications written in COBOL, RPG, Java and CA 2E (Synon) as well as other languages. For organizations enhancing or replacing legacy applications, CM First has advanced code comprehension, business rule mining, and transformation software that reduces engineering costs by up to 80 percent. Scaling to millions of lines of code from programs, jobs and tables with compiler accuracy, CM First uses code slicing technology to present a new way to navigate code visually. For systems integrators who need to compete with low-cost competitors, CM First software increases project margins and improves project estimation accuracy by enabling a profitable and fixed price commercial model. About The Rice Alliance for Technology and Entrepreneurship: The Rice Alliance for Technology and Entrepreneurship (Rice Alliance) is Rice University’s globally-recognized initiative devoted to the support of technology commercialization, entrepreneurship education, and the launch of technology companies. Since inception, more than 1,800 early-stage companies have benefited from participating at the 150+ programs hosted by the Rice Alliance and raised more than $4.2 billion in funding.


News Article | February 20, 2017
Site: www.eurekalert.org

Understanding how the brain remembers can one day shed light on what went wrong when memory fails, such as it occurs in Alzheimer's disease. Researchers at Baylor College of Medicine and Rice University reveal for the first time the specific patterns of electrical activity in rat brains that are associated with specific memories, in this case a fearful experience. They discovered that before rats avoid a place in which they had a fearful experience, the brain recalled memories of the physical location where the experience occurred. The results appear in Nature Neuroscience. "We recall memories all the time," said senior author Dr. Daoyun Ji, associate professor of molecular and cellular biology at Baylor. "For example, I can recall the route I take from home to work every morning, but what are the brain signals at this moment when I hold this memory in my mind?" Studying the workings of the brain in people is difficult, so scientists have turned to the laboratory rat. They have learned that when the animal is in a particular place, neurons in the hippocampus, appropriately called place cells, generate pulses of activity. "A number of place cells generates electrical activity called a 'spiking pattern,'" Ji said. "When the rat is in a certain place, a group of neurons generates a specific pattern of spikes and when it moves to a different place, a different group of neurons generates another pattern of spikes. The patterns are very distinct. We can predict where the animal is by looking at its pattern of brain activity." But, are these spiking patterns involved in memory? How to know what a rat is thinking "Our laboratory rats cannot tell us what memory they are recalling at any particular time," Ji said. "To overcome that, we designed an experiment that would allow us to know what was going on in the animal's brain right before a certain event." In the experiment, conducted by first author Chun-Ting Wu, graduate researcher at the Ji lab, a rat walked along a track, back and forth. After a period of rest, the rat walked the same track again, but when the animal approached the end of the track, it received a mild shock. After it rested again, the rat was placed back on the track. This time, however, when it approached the end of the track where it had received the mild shock before, the rat stopped and turned around, avoiding crossing the fearful path. "Before a rat walked the tracks the first time, we inserted tiny probes into its hippocampus to record the electrical signals generated by groups of active neurons," Ji said. "By recording these brain signals while the animal walked the track for the first time we could examine the patterns that emerged in its brain - we could see what patterns were associated with each location on the track, including the location where the animal later got shocked." "Because the rat turns around and avoids stepping on the end of the track after the shocks, we can reasonably assume that the animal is thinking about the place where it got shocked at the precise moment that it stops walking and turns away," Ji said. "Our observations confirmed this idea." When the researchers, in collaboration with co-author Dr. Caleb Kemere at Rice University, looked at the brain activity in place neurons at this moment, they found that the spiking patterns corresponding to the location in which the rat had received the shock re-emerged, even though this time the animal was only stopping and thinking about the location. "Interestingly, from the brain activity we can tell that the animal was 'mentally traveling' from its current location to the shock place. These patterns corresponding to the shock place re-emerged right at the moment when a specific memory is remembered," Ji said. The next goal of the researchers is to investigate whether the spiking pattern they identified is absolutely required for the animals to behave the way they did. "If we disrupt the pattern, will the animal still avoid stepping into the zone it had learned to avoid?" Ji said. "We are also interested in determining how the spiking patterns of place neurons in the hippocampus can be used by other parts of the brain, such as those involved in making decisions." Ji and his colleagues are also planning on exploring what role spiking patterns in the hippocampus might play in diseases that involve memory loss, such as Alzheimer's disease. "We want to determine whether this kind of mechanism is altered in animal models of Alzheimer's disease. Some evidence shows that it is not that the animals don't have a memory, but that somehow they cannot recall it. Using our system to read spiking patterns in the brains of animal models of the disease, we hope to determine whether a specific spiking pattern exists during memory recall. If not, we will explore the possibility that damaged brain circuits are preventing the animal from recalling the memory and look at ways to allow the animal to recall the specific activity patterns, the memory, again." Dr. Daniel Haggerty, a post-doctoral associate in the Ji lab, also contributed to this work. This study was supported by grants from the National Institutes of Health (R01MH106552) and the Simons Foundation (#273886).


News Article | February 24, 2017
Site: www.eurekalert.org

New Rochelle, NY, February 24, 2017--Researchers have used tissue engineering to create models for studying the bone-destroying activity of tumors such as the aggressive pediatric cancer Ewing's sarcoma. A new 3-dimensional, living model of the osteolytic process and bone remodeling, which can serve a valuable tool for exploring disease mechanisms and the effectiveness of potential treatments, is described in Tissue Engineering, Part C, Methods, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. The article is available free on the Tissue Engineering website until March 24, 2017. In the article entitled "Tissue-Engineered Model of Human Osteolytic Bone Tumor," Gordana Vunjak-Novakovic and coauthors from Columbia University, New York, NY and Politecnico di Milano, Italy, present the methods used to bioengineer a living Ewing's sarcoma model that includes both osteoclasts and osteoblasts in a controllable biomimetic environment. The researchers demonstrate the usefulness of the model for testing anti-osteolytic drugs. "There is an urgent need for the development of human-like tumor models. This article is an excellent example of the progress being made," says Methods Co-Editor-in-Chief John A. Jansen, DDS, PhD, Professor and Head, Department of Biomaterials, Radboud University Medical Center, The Netherlands. Research reported in this publication was supported by the National Institutes of Health under Award Numbers EB002520 and EB17103. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Tissue Engineering is an authoritative peer-reviewed journal published monthly online and in print in three parts: Part A, the flagship journal published 24 times per year; Part B: Reviews, published bimonthly, and Part C: Methods, published 12 times per year. Led by Co-Editors-In-Chief Antonios Mikos, PhD, Louis Calder Professor at Rice University, Houston, TX, and Peter C. Johnson, MD, Principal, MedSurgPI, LLC, President and CEO, Scintellix, LLC, Raleigh, NC, the Journal brings together scientific and medical experts in the fields of biomedical engineering, material science, molecular and cellular biology, and genetic engineering. Tissue Engineering is the official journal of the Tissue Engineering & Regenerative Medicine International Society (TERMIS). Complete tables of content and a sample issue may be viewed online at the Tissue Engineering website. Mary Ann Liebert, Inc., publishers is a privately held, fully integrated media company known for establishing authoritative peer-reviewed journals in many promising areas of science and biomedical research, including Stem Cells and Development, Human Gene Therapy, and Advances in Wound Care. Its biotechnology trade magazine, GEN (Genetic Engineering & Biotechnology News), was the first in its field and is today the industry's most widely read publication worldwide. A complete list of the firm's 80 journals, books, and newsmagazines is available on the Mary Ann Liebert, Inc., publishers website.


News Article | March 2, 2017
Site: www.rdmag.com

Controlled nuclear fusion has been a holy grail for physicists who seek an endless supply of clean energy. Scientists at Rice University, the University of Illinois at Urbana-Champaign and the University of Chile offered a glimpse into a possible new path toward that goal. Their report on quantum-controlled fusion puts forth the notion that rather than heating atoms to temperatures found inside the sun or smashing them in a collider, it might be possible to nudge them close enough to fuse by using shaped laser pulses: ultrashort, tuned bursts of coherent light. Authors Peter Wolynes of Rice, Martin Gruebele of Illinois and Illinois alumnus Eduardo Berrios of Chile simulated reactions in two dimensions that, if extrapolated to three, might just produce energy efficiently from deuterium and tritium or other elements. Their paper appears in the festschrift edition of Chemical Physical Letters dedicated to Ahmed Zewail, Gruebele's postdoctoral adviser and a Nobel laureate for his work on femtochemistry, in which femtosecond-long laser flashes trigger chemical reactions. The femtochemical technique is central to the new idea that nuclei can be pushed close enough to overcome the Coulomb barrier that forces atoms of like charge to repel each other. When that is accomplished, atoms can fuse and release heat through neutron scattering. When more energy is created than it takes to sustain the reaction, sustained fusion becomes viable. The trick is to do all this in a controlled way, and scientists have been pursuing such a trick for decades, primarily by containing hydrogen plasmas at sun-like temperatures (at the U.S. Department of Energy's National Ignition Facility and the International Thermonuclear Experimental Reactor effort in France) and in large facilities. The new paper describes a basic proof-of-principle simulation that shows how, in two dimensions, a shaped-laser pulse would push a molecule of deuterium and tritium, its nuclei already poised at a much smaller internuclear distance than in a plasma, nearly close enough to fuse. "What prevents them from coming together is the positive charge of the nuclei, and both of these nuclei have the smallest charge, 1," Wolynes said. He said 2-D simulations were necessary to keep the iterative computations practical, even though doing so required stripping electrons from the model molecules. "The best way to do it would be to leave the electrons on to help the process and control their motions, but that is a higher-dimensional problem that we -- or someone -- will tackle in the future," Wolynes said. Without the electrons, it was still possible to bring nuclei within a small fraction of an angstrom by simulating the effects of shaped 5-femtosecond, near-infrared laser pulses, which held the nuclei together in a "field-bound" molecule. "For decades, researchers have also investigated muon-catalyzed fusion, where the electron in the deuterium/tritium molecule is replaced by a muon," Gruebele said. "Think of it as a 208-times heavier electron. As a result, the molecular bond distance shrinks by a factor of 200, poising the nuclei even better for fusion. "Sadly, muons don't live forever, and the increased fusion efficiency just falls short of breaking even in energy output," he said. "But when shaped vacuum ultraviolet laser pulses become as available as the near-infrared ones we simulated here, quantum control of muonic fusion may get it over the threshold." Because the model works at the quantum level -- where subatomic particles are subject to different rules and have the characteristics of both particles and waves -- the Heisenberg uncertainty principle comes into play. That makes it impossible to know the precise location of particles and makes tuning the lasers a challenge, Wolynes said. "It's clear the kind of pulses you need have to be highly sculpted and have many frequencies in them," he said. "It will probably take experimentation to figure out what the best pulse shape should be, but tritium is radioactive, so no one ever wants to put tritium in their apparatus until they're sure it's going to work." Wolynes said he and Gruebele, whose lab studies protein folding, cell dynamics, nanostructure microscopy, fish swimming behavior and other topics, have been thinking about the possibilities for about a decade, even though nuclear fusion is more of a hobby than a profession for both. "We finally got the courage to say, 'Well, it's worth saying something about it.' "We're not starting a company ... yet," he said. "But there may be angles here other people can think through that would lead to something practical even in the short term, such as production of short alpha particle pulses that could be useful in research applications. "I'd be lying if I said that when we started the calculation, I didn't hope it might just solve mankind's energy problems," Wolynes said. "At this point, it doesn't. On the other hand, I think it's an interesting question that starts us on a new path."


News Article | February 28, 2017
Site: www.eurekalert.org

Tens of millions of Americans with lung disease use metered-dose inhalers each day, and new studies by Rice University electrical engineers and pulmonologists at Baylor College of Medicine have identified critical errors that are causing many inhaler users to get only about half as much medicine as they should from each puff. "Metered-dose inhalers are used every day by people with asthma, COPD and other chronic lung diseases, and the vast majority of the time -- between 70 and 90 percent -- patients make mistakes that keep some of the medicine from making it to their lungs," said Ashutosh Sabharwal, professor of electrical and computer engineering at Rice and co-author of two recent studies about the phenomenon. "While inhalers are the most efficient delivery mechanism for many patients, these devices require deft maneuvers on the part of patients. The common errors are well-known, but fixing them continues to be a challenge." Sabharwal's team at Rice's Scalable Health Lab uses the latest electronic technology -- smartphones, wearable devices and inexpensive sensors and components -- to address this and similar health and wellness issues. The lab's creations to date include a self-use retinal imaging system, a mobile spirometer, wearable technology for dietary monitoring and apps for evaluating depression and extracting accurate vitals signs from videos. In partnership with pulmonologist Nick Hanania, associate professor of medicine and director of the Airways Clinical Research Center at Baylor College of Medicine, Sabharwal and Rice graduate student Rajoshi Biswas co-authored of two recent studies aimed at finding out which mistakes are most common and how they impact the amount of medicine that reaches patients' lungs. "For years, we as clinicians have known that our patients do not use their inhalers as they should," Hanania said. "In the best case, a puff from an inhaler results in about 40 percent of the medicine reaching the lungs. In the worst case, if someone does everything wrong, that drops to 7 percent. We know the two extremes, but the vast majority of everyday use falls somewhere in the middle. In this study, we have been able to objectively measure the errors, and, using new technology, learn about their impact on drug delivery to the lungs." Biswas, a Ph.D. student in Rice's Scalable Health Lab, spent six years gathering evidence for the studies. She has measured how patients use inhalers, explored the mathematics of their inhalation patterns, examined how doctors and therapists evaluate inhaler use and created an experimental setup to mimic human inhaler use. The research was spurred by an observation she kept returning to just after she came to Rice in 2011 Virtually all the inhaler-dosing studies she found focused on best-case scenarios, the rare cases where patients used the inhaler perfectly, even though the average case was far from perfect. Biswas said it's important to have accurate dosing information for average use. "What's been lacking is a rigorous quantitative examination of how much medicine is making it to the lungs for those everyday cases," she said. Biswas said errors are common because inhaler use requires precision, timing and coordination. Even the slightest deviation can significantly reduce the amount of medicine that reaches the lungs. For example, in a study in the journal CHEST involving 23 Houston patients who have asthma or COPD, each patient made at least one error. Inhalers should be shaken for a few seconds before each use. Biswas said patients often forget to shake the device or don't shake it long enough, particularly on subsequent puffs. The angle at which the inhaler is held is also critical. Slight deviations can result in much of the medicine striking and sticking to the tongue or mouth. Patients also must draw a breath when they activate the inhaler, and the timing, duration and force of this inhalation are critical. Finally, patients are supposed to hold their breath for 10 seconds to allow for uptake of medicine that reaches the lungs. To model how much medicine reaches the lungs for everyday cases, Biswas started by measuring the airflow characteristics from eight patients as they drew breath at various rates. With that data, she programed a machine to simulate the flow, duration and force of different patterns of human inhalation. This breathing device became one piece of an experimental setup that included a robotic finger to activate the inhaler and a metal tube milled in the precise configuration of an adult mouth and throat. Once the metal "throat" was sprayed with a thin coating of oil, it precisely mimicked the wet, sticky conditions that tend to trap medicine in the mouth and throat of patients. Using these components, she was able to precisely measure how much medicine made it to the lungs in a variety of scenarios where patients mistime their breaths or make other common mistakes. "The thing that matters the most is coordination," she said. "It's vital to start breathing just before or at the exact same time the inhaler is activated. A delay of just a half second between pressing the inhaler and breathing in was enough to limit lung deposition to about 20 percent -- about half of what a patient would get in the ideal case." In cases where the machine started inhaling just before the inhaler was activated, Biswas found that more than 35 percent of medication reached the lungs. "In this situation, where timing is coordinated, the determining factor for lung deposition is the flow rate," Biswas said. "Based on our findings, the ideal scenario is to inhale deeply at higher flow rates for about three seconds to fully inhale, and to activate the inhaler about a half second after starting to inhale. This helps ensure the medication clears the mouth-throat cavity and reaches the lungs." Sabharwal, Hanania and Biswas said they hope the medical community will examine their latest study in the Journal of Aerosol Medicine and Pulmonary Drug Delivery and consider further research to evaluate and update recommended guidelines for inhaler use and set up educational strategies for their patients. "Our results differ from the current Global Initiative for Asthma inhaler use guidelines," Sabharwal said. "The propellant used in inhalers has changed in recent years, and the current guidelines were developed based on studies of the old inhalers. Our findings, coupled with the recent changes in inhaler propellants, suggest it is time to revisit these guidelines." The research was funded partially by the National Institutes of Health. The DOI of the study in the Journal of Aerosol Medicine and Pulmonary Drug Delivery is: 10.1089/jamp.2015.1278 A copy of the study in the Journal of Aerosol Medicine and Pulmonary Drug Delivery is available at: http://online. The DOI of the CHEST paper is: 10.1016/j.chest.2016.08.017 A copy of the CHEST paper is available at: http://dx. This release can be found online at news.rice.edu. Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | February 15, 2017
Site: www.eurekalert.org

A chunk of conductive graphene foam reinforced by carbon nanotubes can support more than 3,000 times its own weight and easily bounce back to its original height, according to Rice University scientists. Better yet, it can be made in just about any shape and size, they reported, demonstrating a screw-shaped piece of the highly conductive foam. The Rice lab of chemist James Tour tested its new "rebar graphene" as a highly porous, conductive electrode in lithium ion capacitors and found it to be mechanically and chemically stable. The research appears in the American Chemical Society journal ACS Applied Materials and Interfaces. Carbon in the form of atom-thin graphene is among the strongest materials known and is highly conductive; multiwalled carbon nanotubes are widely used as conductive reinforcements in metals, polymers and carbon matrix composites. The Tour lab had already used nanotubes to reinforce two-dimensional sheets of graphene. Extending the concept to macroscale materials made sense, Tour said. "We developed graphene foam, but it wasn't tough enough for the kind of applications we had in mind, so using carbon nanotubes to reinforce it was a natural next step," Tour said. The three-dimensional structures were created from a powdered nickel catalyst, surfactant-wrapped multiwall nanotubes and sugar as a carbon source. The materials were mixed and the water evaporated; the resulting pellets were pressed into a steel die and then heated in a chemical vapor deposition furnace, which turned the available carbon into graphene. After further processing to remove remnants of nickel, the result was an all-carbon foam in the shape of the die, in this case a screw. Tour said the method will be easy to scale up. Electron microscope images of the foam showed partially unzipped outer layers of the nanotubes had bonded to the graphene, which accounted for its strength and resilience. Graphene foam produced without the rebar could support only about 150 times its own weight while retaining the ability to rapidly return to its full height. But rebar graphene irreversibly deformed by about 25 percent when loaded with more than 8,500 times its weight. Junwei Sha, a visiting graduate student at Rice and a graduate student at Tianjin University, China, is lead author of the paper. Co-authors from Rice are postdoctoral researchers Rodrigo Salvatierra, Pei Dong and Yongsung Ji; graduate students Yilun Li, Tuo Wang, Chenhao Zhang and Jibo Zhang; former postdoctoral researcher Seoung-Ki Lee; Pulickel Ajayan, chair of the Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry; and Jun Lou, a professor of materials science and nanoengineering. Naiqin Zhao, a professor at Tianjin University and a researcher at the Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, is also a co-author. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice. The Air Force Office of Scientific Research and its Multidisciplinary University Research Initiative supported the research. This news release can be found online at http://news. A piece of rebar graphene stands up to a good soaking in a test at Rice University. (Credit: Tour Group/Rice University) Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | March 2, 2017
Site: www.eurekalert.org

Controlled nuclear fusion has been a holy grail for physicists who seek an endless supply of clean energy. Scientists at Rice University, the University of Illinois at Urbana-Champaign and the University of Chile offered a glimpse into a possible new path toward that goal. Their report on quantum-controlled fusion puts forth the notion that rather than heating atoms to temperatures found inside the sun or smashing them in a collider, it might be possible to nudge them close enough to fuse by using shaped laser pulses: ultrashort, tuned bursts of coherent light. Authors Peter Wolynes of Rice, Martin Gruebele of Illinois and Illinois alumnus Eduardo Berrios of Chile simulated reactions in two dimensions that, if extrapolated to three, might just produce energy efficiently from deuterium and tritium or other elements. Their paper appears in the festschrift edition of Chemical Physical Letters dedicated to Ahmed Zewail, Gruebele's postdoctoral adviser and a Nobel laureate for his work on femtochemistry, in which femtosecond-long laser flashes trigger chemical reactions. The femtochemical technique is central to the new idea that nuclei can be pushed close enough to overcome the Coulomb barrier that forces atoms of like charge to repel each other. When that is accomplished, atoms can fuse and release heat through neutron scattering. When more energy is created than it takes to sustain the reaction, sustained fusion becomes viable. The trick is to do all this in a controlled way, and scientists have been pursuing such a trick for decades, primarily by containing hydrogen plasmas at sun-like temperatures (at the U.S. Department of Energy's National Ignition Facility and the International Thermonuclear Experimental Reactor effort in France) and in large facilities. The new paper describes a basic proof-of-principle simulation that shows how, in two dimensions, a shaped-laser pulse would push a molecule of deuterium and tritium, its nuclei already poised at a much smaller internuclear distance than in a plasma, nearly close enough to fuse. "What prevents them from coming together is the positive charge of the nuclei, and both of these nuclei have the smallest charge, 1," Wolynes said. He said 2-D simulations were necessary to keep the iterative computations practical, even though doing so required stripping electrons from the model molecules. "The best way to do it would be to leave the electrons on to help the process and control their motions, but that is a higher-dimensional problem that we -- or someone -- will tackle in the future," Wolynes said. Without the electrons, it was still possible to bring nuclei within a small fraction of an angstrom by simulating the effects of shaped 5-femtosecond, near-infrared laser pulses, which held the nuclei together in a "field-bound" molecule. "For decades, researchers have also investigated muon-catalyzed fusion, where the electron in the deuterium/tritium molecule is replaced by a muon," Gruebele said. "Think of it as a 208-times heavier electron. As a result, the molecular bond distance shrinks by a factor of 200, poising the nuclei even better for fusion. "Sadly, muons don't live forever, and the increased fusion efficiency just falls short of breaking even in energy output," he said. "But when shaped vacuum ultraviolet laser pulses become as available as the near-infrared ones we simulated here, quantum control of muonic fusion may get it over the threshold." Because the model works at the quantum level -- where subatomic particles are subject to different rules and have the characteristics of both particles and waves -- the Heisenberg uncertainty principle comes into play. That makes it impossible to know the precise location of particles and makes tuning the lasers a challenge, Wolynes said. "It's clear the kind of pulses you need have to be highly sculpted and have many frequencies in them," he said. "It will probably take experimentation to figure out what the best pulse shape should be, but tritium is radioactive, so no one ever wants to put tritium in their apparatus until they're sure it's going to work." Wolynes said he and Gruebele, whose lab studies protein folding, cell dynamics, nanostructure microscopy, fish swimming behavior and other topics, have been thinking about the possibilities for about a decade, even though nuclear fusion is more of a hobby than a profession for both. "We finally got the courage to say, 'Well, it's worth saying something about it.' "We're not starting a company ... yet," he said. "But there may be angles here other people can think through that would lead to something practical even in the short term, such as production of short alpha particle pulses that could be useful in research applications. "I'd be lying if I said that when we started the calculation, I didn't hope it might just solve mankind's energy problems," Wolynes said. "At this point, it doesn't. On the other hand, I think it's an interesting question that starts us on a new path." Berrios, lead author of the paper, is a research scientist at the University of Chile, Santiago. Wolynes is the D.R. Bullard-Welch Foundation Professor of Science, a professor of chemistry, of biochemistry and cell biology, of physics and astronomy and of materials science and nanoengineering at Rice and a senior investigator at Rice's National Science Foundation-funded Center for Theoretical Biological Physics. Gruebele is the head of chemistry, the James R. Eiszner Endowed Chair in Chemistry and a professor of physics, biophysics and computational biology at Illinois. This news release can be found online at http://news. Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | March 3, 2017
Site: www.greencarcongress.com

« Oil Majors’ Costs Have Risen 66% Since 2011 | Main | Senate bill would enable sales of E15 and higher ethanol blends year round; RVP waiver » Scientists at Rice University, the University of Illinois at Urbana-Champaign and the University of Chile are proposing that quantum-controlled motion of nuclei, starting from the nanometer-size ground state of a molecule, can potentially overcome some of the difficulties of thermonuclear fusion by compression of a fuel pellet or in a bulk plasma. Their report on quantum-controlled fusion suggests that rather than heating atoms to temperatures found inside the sun or smashing them in a collider, it might be possible to nudge them close enough to fuse by using shaped laser pulses: ultrashort, tuned bursts of coherent light. Fusion reactions also can be induced by non-thermal means. For example, charged particle beams can be collided at appropriately high energy to carry out fusion reactions in the laboratory. Alternatively, fusion can be catalyzed by achieving a high spatial density, as happens for the nuclei within a muonic molecule. When a muon replaces the electron, it brings the nuclei ~200 times closer together than in an ordinary molecule, greatly enhancing the spontaneous nuclear reaction rate even at low temperature. In many ways, the ground state of such a molecule is the ideal situation for fusion because the phase space density of the reacting species takes on the largest possible value consistent with quantum mechanics. While greeted by much excitement when it was discovered in the 1950s, muon-catalyzed fusion still just falls a bit short of practicality because of the insufficient lifetime of the muon. Peter Wolynes of Rice, Martin Gruebele of Illinois and Illinois alumnus Eduardo Berrios of Chile simulated reactions in two dimensions that, if extrapolated to three, might just produce energy efficiently from deuterium and tritium or other elements. Their paper appears in the festschrift edition of Chemical Physical Letters dedicated to Ahmed Zewail, Gruebele’s postdoctoral adviser and a Nobel laureate for his work on femtochemistry, in which femtosecond-long laser flashes trigger chemical reactions. The femtochemical technique is central to the new idea that nuclei can be pushed close enough to overcome the Coulomb barrier that forces atoms of like charge to repel each other. When that is accomplished, atoms can fuse and release heat through neutron scattering. When more energy is created than it takes to sustain the reaction, sustained fusion becomes viable. The trick is to do all this in a controlled way, and scientists have been pursuing such a trick for decades, primarily by containing hydrogen plasmas at sun-like temperatures (at the US Department of Energy’s National Ignition Facility and the International Thermonuclear Experimental Reactor effort in France) and in large facilities. The new paper describes a basic proof-of-principle simulation that shows how, in two dimensions, a shaped-laser pulse would push a molecule of deuterium and tritium, its nuclei already poised at a much smaller internuclear distance than in a plasma, nearly close enough to fuse. … we performed quantum wavepacket propagation in a 2-D toy model of two field-bound nuclei in the presence of a time-dependent 800 nm laser pulse that was shaped to exert coherent control over the nuclear wavepacket. The collision probability is enhanced by about 3 orders of magnitude by the best coherent control pulse, and by up to 20 orders of magnitude relative to an electron-bound molecule. Since muonic fusion is already not far from break-even for net energy production, shaped VUV laser pulses, when they become available, could also be an efficient means of enhancing muonic fusion by coherent control. Wolynes said 2-D simulations were necessary to keep the iterative computations practical, even though doing so required stripping electrons from the model molecules. Without the electrons, it was still possible to bring nuclei within a small fraction of an angstrom by simulating the effects of shaped 5-femtosecond, near-infrared laser pulses, which held the nuclei together in a “field-bound” molecule. Because the model works at the quantum level—where subatomic particles are subject to different rules and have the characteristics of both particles and waves—the Heisenberg uncertainty principle comes into play. That makes it impossible to know the precise location of particles and makes tuning the lasers a challenge, Wolynes said. Wolynes said he and Gruebele, whose lab studies protein folding, cell dynamics, nanostructure microscopy, fish swimming behavior and other topics, have been thinking about the possibilities for about a decade, even though nuclear fusion is more of a hobby than a profession for both. Berrios, lead author of the paper, is a research scientist at the University of Chile, Santiago. Wolynes is the D.R. Bullard-Welch Foundation Professor of Science, a professor of chemistry, of biochemistry and cell biology, of physics and astronomy and of materials science and nanoengineering at Rice and a senior investigator at Rice's National Science Foundation-funded Center for Theoretical Biological Physics. Gruebele is the head of chemistry, the James R. Eiszner Endowed Chair in Chemistry and a professor of physics, biophysics and computational biology at Illinois.


News Article | March 1, 2017
Site: www.eurekalert.org

African-American and poor children in the United States suffer disproportionately from asthma. But according to a new study from sociologists at Rice University, racial and socio-economic gaps in the proportion of children in Houston who have asthma may be a result of social inequalities in the neighborhoods where children live. "Comprehensive Neighborhood Portraits and Child Asthma Disparities" will appear in an upcoming edition of the Maternal and Child Health Journal. In the study, the researchers found that of the 12,000+ children in Houston who have asthma, the chronic disease of airways in the lungs is more prevalent among African-American children than white children and occurs most often among African-American children living in poor neighborhoods. The researchers also found that children of all races and ethnicities, including white children, have a greater risk of developing asthma when they live in poor neighborhoods, compared with children living in middle-class or affluent neighborhoods. "We set out to find out if there is a concentration of children in different neighborhoods that was more likely to have asthma," said lead author Ashley Kranjac, a postdoctoral research fellow in the Department of Sociology and the Kinder Institute Urban Health Program at Rice. "We found, as others have, that asthma is more widespread among African-American children and children in poor neighborhoods. But in addition, we found that African-American children suffer disproportionately in every kind of neighborhood, from the poorest to the wealthiest." All Houston neighborhoods were classified using several social and economic characteristics. One such characteristic was median household income; the researchers reported that the most affluent neighborhoods in Houston had median household incomes of over $100,000. Middle-class neighborhoods were at $58,100 and poor neighborhoods had median household incomes of just $33,900. Using these classifications, the researchers found that African-American children, when compared with white children living in the same type of neighborhood, were 8.8 percent more likely to have asthma in poor neighborhoods, 6.7 percent more likely in middle-class neighborhoods and 5.8 percent more likely in affluent communities. In addition, the likelihood of being diagnosed with asthma increased for all children in Houston as they got older. For example, 6 percent of children in Houston between the ages of 2 and 6 have asthma, but 8 percent of children between the ages of 7 and 12 have asthma. And children growing up in the poorest neighborhoods are twice as likely to have an asthma diagnosis compared with children growing up in the most affluent neighborhoods. Kranjac said that although the research did not provide a reason why African-American children growing up in poor neighborhoods were more likely to suffer from asthma, she theorized that it could partly have to do with socio-economic differences. "Higher levels of income and higher levels of education go hand in hand," Kranjac said. "It may be that parents with more education have greater access to information on poor air quality and its effects on asthma. These individuals may not only be more likely to know how to access information on air quality but also decide to have their children play inside or be able to travel outside of their community on poor air quality days. Individuals with less education and/or income may not have access to that kind of information and/or may not have the resources to pursue alternative activities on poor air quality days. They likely also have fewer housing choices and have to settle for housing in the poorest air quality areas of the city." Kranjac said that it is equally concerning that African-American children, even in the wealthiest neighborhoods, are disproportionately suffering from asthma. "The drivers of those differences are not likely physiological but rooted in social and racial inequalities," she said. The researchers used the medical records of 206,974 children aged 2-12 in 1,076 Houston metropolitan neighborhoods (Census tracts). Social and economic information was generated using the 2010 Census and the 2009-2013 American Community Survey data. Air quality data was provided by the Texas Commission on Environmental Quality and the Texas Air Monitoring Information System from 2010 to 2012. Kranjac and her coauthors hope the research will lead others to treat social and racial inequalities as central drivers of the asthma gap in children. The study is available online at https:/ and was funded by Houston Endowment. For more information, contact Amy McCaig, senior media relations specialist at Rice, at 713-348-6777 or amym@rice.edu. This news release can be found online at http://news. . Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | February 15, 2017
Site: www.prweb.com

Pink Petro, the community for women in energy, will gather industry executives, professionals and students on March 8 for the second HERWorld Energy Forum at the Jones Graduate School of Business on the campus of Rice University. The event will be streamed globally with U.S. local events in Denver, Baton Rouge, New Orleans, Bakersfield, Wheeling and Puget Sound. Internationally, forums will be held in Kenya, Nigeria, The United Kingdom and parts of Western Europe. Celebrating on International Women's Day, the event begins at 8:00 a.m. and ends at 5:00 p.m. Central Time. The forum is a unique event that addresses new frontiers in the energy industry where business, workforce, innovation and policy intersect. This year's theme is "The Next Era of Energy: Lean In, All In, and Join In." ABC-TV anchor Gina Gaston and Editor-in-Chief of the Houston Business Journal Giselle Greenwood will co-emcee. Katie Mehnert, founder and CEO of Pink Petro, said, "The evidence of dramatic change is all around us, and it’s happening at exponential speed. The global energy industry is entering the dawn of a new era and for the workforce, that's exciting." “Our location in Houston, our eye to the future, and our support of diversity and inclusion make this collaboration with Pink Petro and the business school a natural fit,” said Peter Rodriguez, dean of the Jones Graduate School of Business. “We are thrilled to be a part of it.” Keynotes include Jeffrey Hayzlett, chairman of the C-Suite Network; Josh Levs, author, UN gender advocate and former CNN correspondent; and Johnna Van Keuren, Vice President, Wind Operations and HSSE, New Energies with Royal Dutch Shell. Presenters include Christina Sistrunk, CEO of Aera Energy; Tandra Jackson, Managing Partner of KPMG LLP; Vicky Bailey, chairman of the United States Energy Association; Dr. Mikki Hebl, Martha and Henry Malcolm Lovett Chair of Psychology and professor of management at Rice University; and Nick Candito, Forbes Top 30 under 30 and co-founder of Progressly. The conference will open with Sami Murphy who will sing her original song, "Energy". For a full agenda, speakers, and registration, visit the HERWorld website. HERWorld17 sponsors include the Jones Graduate School of Business at Rice University, KPMG LLP, Shell, GE, Spectra Energy, Marathon Oil, Cabot Oil & Gas Corporation, S&B Engineering and Constructors, Progressly, Workday, Challenger Gray Christmas, Spring Rock Energy, The Golden Tulip Nairobi. Hosts include The University of Colorado Denver Global Energy Management Program and the LSU Center for Energy Studies. Pink Petro is a leading professional development company and online professional community aimed at disrupting the gender gap in energy and defining the future of the workforce and supply chain. Pink Petro™ has members in 120+ countries in 500+ companies across the energy value chain.


Just in time for Presidents' Day, the presidential rankings are in. According to C-SPAN’s Presidential History Survey 2017, former President Barack Obama is the 12th best presidential leader in United States' history. Using a database of C-SPAN programming, 91 historians and presidential scholars evaluated the 44 presidents by giving them a score between one and 10 on 10 different leadership qualities such as “economic management,” “crisis leadership,” “moral authority,” and “vision/setting an agenda.” Recommended: Know your US presidents? See if D.C. Decoder can stump you! Mr. Obama did best in the “pursued equal justice for all,” category with an overall average of 83.2, placing him third behind Abraham Lincoln (first) and Lyndon Johnson (second). His worst performing category was “relations with Congress,” with a score of 37.8, placing him fifth from the bottom, just beneath William Harrison and Richard Nixon. This is the third such ranking, with previous C-SPAN surveys published in 2000 and 2009. As No. 12, Obama falls below Johnson (10th) and Woodrow Wilson (11th), and above James Monroe (13th) and James K. Polk (14th). Abraham Lincoln has consistently ranked as the best US president for the three surveys, followed by George Washington and Franklin D. Roosevelt. “Once again the Big Three are Lincoln, Washington and FDR – as it should be,” says Rice University historian and survey adviser Douglas Brinkley in a press release. “That Obama came in at number 12 his first time out is quite impressive. And the survey is surprisingly good news for George W. Bush, who shot up a few notches.” Other historians are surprised Obama wasn’t higher on the list. “Although 12th is a respectable overall ranking, one would have thought that former President Obama’s favorable rating when he left office would have translated into a higher ranking in this presidential survey. I am especially surprised that he was ranked at 7th in moral authority, despite heading a scandal-free administration,” says Dr. Edna Greene Medford, a history professor at Howard University and survey adviser. “But, of course, historians prefer to view the past from a distance, and only time will reveal his legacy.” Even though a president’s time in office has passed, their ranking is history is anything but absolute. Along with George W. Bush's improvement, Dwight Eisenhower also moved up three spots to claim No. 5. Andrew Jackson is the biggest loser of the 2017 survey, who moved down five spots to number 18. Thus, Obama could one year break into the Top 10 as his presidency continues to be compared against future and past presidents. He is currently lagging 18 points behind 10th place Johnson. Obama, Bill Clinton (15th), and George H.W. Bush (20th) are the only living former presidents to make the Top 20. “There tends to be kind of an upward mobility, particularly if you are a president who had no major scandals,” Professor Brinkley tells NBC. “If the Trump presidency is problematic, people may judge Obama even higher yet.” James Buchanan is listed as the worst president, with Franklin Pierce and Andrew Johnson earning next lowest spots. It does not bode well for their legacy that all three of these presidents were also put in the bottom three in 2000 and 2009. And along with John Tyler and Warren G. Harding, these three presidents are rated lower than William Henry Harrison who only served as president for one month. “You never want to be lower than William Henry Harrison,” says Brinkley. “If you're below Harrison, the thought is that that you really damaged the executive branch during your tenure in office.” Become a part of the Monitor community


Studer C.,Rice University | Larsson E.G.,Linköping University
IEEE Journal on Selected Areas in Communications | Year: 2013

We investigate an orthogonal frequency-division multiplexing (OFDM)-based downlink transmission scheme for large-scale multi-user (MU) multiple-input multiple-output (MIMO) wireless systems. The use of OFDM causes a high peak-to-average (power) ratio (PAR), which necessitates expensive and power-inefficient radio-frequency (RF) components at the base station. In this paper, we present a novel downlink transmission scheme, which exploits the massive degrees-of-freedom available in large-scale MU-MIMO-OFDM systems to achieve low PAR. Specifically, we propose to jointly perform MU precoding, OFDM modulation, and PAR reduction by solving a convex optimization problem. We develop a corresponding fast iterative truncation algorithm (FITRA) and show numerical results to demonstrate tremendous PAR-reduction capabilities. The significantly reduced linearity requirements eventually enable the use of low-cost RF components for the large-scale MU-MIMO-OFDM downlink. © 2012 IEEE.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.98K | Year: 2010

Surface analysis of many classes of large polymers (e.g. non-polar synthetic polymer) by laser desorption mass spectrometry (LDMS) is not possible using existing MALDI matrices. Here, we uniquely address this problem by combining two recent proprietary commercial products available exclusively from Ionwerks. 1) A nanoparticulate ion implanter decorates a surface with size selected metal or alloy nanoparticulates (NPs) yielding efficient LDMS (intact ions and neutrals). 2) Moreover, our LD ion mobility MS allows submicron spatial analysis of directly ejected ions liberated from these NP treated surfaces. Not only does the “gas phase electrophoresis” of the Ion Mobility sort molecular ions by chemical type, but predominantly desorbed neutrals are localized in space above the sample surface long enough to be ionized by additional laser pulses. Our nanoparticulate implanter is the ideal platform for determining the worth of plasmon resonances to LDMS. NP size, shape, and composition can be tailored to increase optical absorption. Are small NP (non plasmon) better matrices than larger NP (plasmon)? Our work shows small particles (1-10 nm gold) are needed for biomolecular tissue imaging. This may not be the general case—especially if the analysis can be accomplished by engineered NP neutral analyte desorption followed by post-ionization. BENEFIT: The anticipated benefit of this research is to provide a nanomatrix which can be utilized for low laser threshold, high spatial resolution surface analyis of large molecular compounds. MALDI analysis of solids as currently practiced requires dissolving the solid sample and combining matrix molecules in a solution which is subsequently dried and introduced into the LDMS for analysis. The analyte must be water soluble. In contrast, here we tackle the more general and pervasive problem of combining matrix with an intact molecular surface. Soft landing or implanting NP into a solid surface in principle (and so far in limited practice with biotissues) provides a universal means of incorporating matrix with any solid surface. Moreover, this approach retains the possibility to image the possible surface molecular heterogeneity (e.g. co-polymer segregation) at submicron spatial resolutions. Whether plasmon resonances turn out to be useful for these analyses can be uniquely and quickly determined for a broad range of nanoparticulates (our source can produce NP from any metal or metal alloy in size ranges from 1-30 nm). Moreover, as we find optimal matrices for soft landing or implantation into solids, it is but a simple matter to produce these same NP compositions and coverages onto a substrate (such as silicon) which can then serve as a MALDI matrix substrate to which analyte molecules in solution can be applied. Dual use applications for this technology include rapid screening of bacterial and virus populations, analysis of intact biofilms, synthetic polymer characterization, and biotissue analysis. Laser desorption MS has been historically dismissed as a surface analysis technique for inorganic surfaces such as semiconductors or strained layer superlattices. However plasmon resonance may provide controlled optical adsorption into the first nm of these solids opening the possibility for LDMS surface analysis of these important materials as well.


News Article | February 16, 2017
Site: www.eurekalert.org

There's at least one person in the world for whom smoking has a beneficial effect, and it took an international collaboration of scientists led by a Rice University professor to figure out why. Rice biochemist John Olson and collaborators in Germany and France helped a young woman and her father understand why she has anemia but her father, who is a smoker, does not. The woman, who was in her 20s when diagnosed, and her father share a mutation in the gene that encodes hemoglobin, the protein in red blood cells responsible for taking up and delivering oxygen to cells around the body. The mutation is one of more than 1,000 discovered so far in adult human hemoglobin. Most appear to have no effect on people, but when medical problems occur, the disease is called a hemoglobinopathy and often named after the city or hospital where it was discovered. In this case, the family was living in Mannheim, Germany, but the father was born in the Turkish city of Kirklareli. The Kirklareli mutation did not affect the iron content of her dad's blood, but did appear to be the root cause of the young woman's chronic anemia, according to the researchers. Further investigation revealed that absorbing carbon monoxide from cigarette smoke is therapeutic for those with this rare genetic disorder. A paper on the research appeared this month in the Journal of Biological Chemistry. The mutation is in the alpha subunit of human hemoglobin (H58L) and causes it to rapidly auto-oxidize, or rust, which causes the protein to fall apart, lose heme and precipitate. As a result, the protein loses its ability to carry oxygen. Eventually, Olson said, the red cells themselves become deformed and are destroyed. Remarkably, this same mutation gives the protein an 80,000-fold higher affinity for carbon monoxide than for oxygen. Carbon monoxide from a cigarette will be selectively taken up by the mutant hemoglobin and prevent it from oxidizing and denaturing. This high affinity for carbon monoxide explained why the father showed no signs of anemia, Olson said. "He may never be an athlete because his blood can't carry as much oxygen, but smoking has prevented him from being anemic," he said. "And there's a side benefit. People with this trait are more resistant to carbon monoxide poisoning." Olson said he does not know how or if the doctors treated the young woman. He doesn't even know her name. But he suspected her iron-deficient anemia was more an annoyance than a threat to her life and would not recommend she start smoking to relieve it. "She shouldn't smoke," he said. "But she could take antioxidants, such as a lot of vitamin C, which would help prevent oxidation of her mutant hemoglobin. Her anemia is not that severe. At the same time, she shouldn't worry too much about secondhand smoke, which might have a positive effect." After ruling out common causes like blood loss, gastritis or congenital defects, her doctors were curious enough about her ailment to call upon Emmanuel Bissé, a researcher at the Institute for Clinical Chemistry and Laboratory Medicine at the University of Freiburg, who discovered the mutation after sequencing her DNA. Bissé in turn recruited Olson and his team to help determine why the histidine-to-leucine change caused anemia in the daughter but not the father. Ironically, Ivan Birukou, a graduate student in Olson's lab, had already generated the same mutation in human hemoglobin (one of several hundred made at Rice) to study how the protein rapidly and selectively binds oxygen. "Emmanuel wrote to me and said, 'I know you've been making all these mutants in hemoglobin, and you've probably done the H58L mutation in (alpha) chains. Does this phenotype make sense?'" Olson recalled. "I said, 'We can do a really neat study here, because we've already made the mutant hemoglobin in a recombinant system.' We actually had a crystal structure (matching Kirklareli) that Ivan and (staff scientist) Jayashree Soman never published but had deposited in the Protein Data Bank. We had made this mutation to try to understand what the distal histidine was doing in alpha subunits." They found in their 2010 study that replacing the histidine, which forms a strong hydrogen bond to oxygen, with leucine caused a dramatic decrease in oxygen affinity and an increase in carbon monoxide binding. Olson and Birukou realized back then that histidine played a key role in discriminating between oxygen and carbon monoxide in hemoglobin. "When Emmanuel wrote to me about his discovery, I already 'knew' what was happening with respect to carbon monoxide binding," Olson said. He said that the normal hydrogen bond causes bound oxygen to stick more tightly to hemoglobin in the same way hydrogen bonds cause spilled soda to feel sticky. "When you touch it, the sugar oxygens and hydrogens make hydrogen bonds with the polysaccharides on your finger," Olson said. "That stickiness helps hold onto oxygen. But leucine is more like an oil, like butane or hexane, and oxygen does not stick well inside hemoglobin. In contrast, bound carbon monoxide is more like methane or ethane and can't form hydrogen bonds." Andres Benitez Cardenas, a postdoctoral researcher in Olson's laboratory, did the crucial experiment in which he put carbon monoxide on the mutant alpha subunit of hemoglobin Kirklareli. The bound carbon monoxide slowed down oxidation of the protein and prevented loss of heme and precipitation. "In effect, Andres did the 'smoking experiment' to show why the father's hemoglobin didn't denature and cause anemia," Olson said. He said the effect caused by Kirklareli, though unusual, is not unique. "There is another 'smoking is good for you' mutation," he said, noting discoveries in Zurich in the late 1970s and early '80s. That case mirrored the current collaboration, as the researchers looking for answers then sought help from Nobel Laureate Max Perutz, whose pioneering work on hemoglobin structures won him the prize in 1968. Olson himself served as a reviewer on some of the papers for hemoglobin Zurich in the 1980s. "Emmanuel knew that we had worked on these histidine-to-leucine mutations in myoglobin and hemoglobin, which is why he contacted us," he said. "This type of collaboration is how science and medicine should work together." Bissé is lead author of the paper. Co-authors are Christine Schaeffer-Reiss, Alain Van Dorsselaer and Tchilabalo Dilezitoko Alayi of the University of Strasbourg, France, and the Hubert CURIEN Multidisciplinary Institute, Strasbourg; Thomas Epting and Karl Winkler of the Institute for Clinical Chemistry and Laboratory Medicine at the University of Freiburg; and Birukou, Benitez Cardenas, Soman and graduate student Premila Samuel at Rice. Birukou is now a technical expert at Syngenta Crop Protection, North Carolina. Olson is the Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology at Rice. This news release can be found online at http://news. Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | February 27, 2017
Site: www.eurekalert.org

Rice University researchers have modeled a nanoscale sandwich, the first in what they hope will become a molecular deli for materials scientists. Their recipe puts two slices of atom-thick graphene around nanoclusters of magnesium oxide that give the super-strong, conductive material expanded optoelectronic properties. Rice materials scientist Rouzbeh Shahsavari and his colleagues built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis and bio-imaging. Their work could help researchers design a range of customizable hybrids of two- and three-dimensional structures with encapsulated molecules, Shahsavari said. The research appears this month in the Royal Society of Chemistry journal Nanoscale. The scientists were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those "made" samples, two-dimensional magnesium oxide in bilayer graphene, Shahsavari said. "We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments," Shahsavari said. Graphene on its own has no band gap - the characteristic that makes a material a semiconductor. But the hybrid does, and this band gap could be tunable, depending on the components, Shahsavari said. The enhanced optical properties are also tunable and useful, he said. "We saw that while this single flake of magnesium oxide absorbed one kind of light emission, when it was trapped between two layers of graphene, it absorbed a wide spectrum. That could be an important mechanism for sensors," he said. Shahsavari said his group's theory should be applicable to other two-dimensional materials, like hexagonal boron-nitride, and molecular fillings. "There is no single material that can solve all the technical problems of the world," he said. "It always comes down to making hybrid materials to synergize the best features of multiple components to do a specific job. My group is working on these hybrid materials by tweaking their components and structures to meet new challenges." Farzaneh Shayeganfar, a visiting research scientist at Rice and researcher at Shahid Rajaee Teacher Training University, Tehran, Iran, is lead author of the paper. Co-authors are Javad Beheshtiyan and Mehdi Neek-Amal, both of Shahid Rajaee and the University of Antwerp, Belgium. Rice University and the Iran Science Elites Federation supported the research. Computing resources were supplied by Rice's National Science Foundation-supported DAVinCI supercomputer administered by Rice's Center for Research Computing and were procured in partnership with Rice's Ken Kennedy Institute for Information Technology. This news release can be found online at http://news. Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl. .


News Article | February 28, 2017
Site: www.cemag.us

Rice University researchers have modeled a nanoscale sandwich, the first in what they hope will become a molecular deli for materials scientists. Their recipe puts two slices of atom-thick graphene around nanoclusters of magnesium oxide that give the super-strong, conductive material expanded optoelectronic properties. Rice materials scientist Rouzbeh Shahsavari and his colleagues built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis, and bio-imaging. Their work could help researchers design a range of customizable hybrids of two- and three-dimensional structures with encapsulated molecules, Shahsavari said. The research appears this month in the Royal Society of Chemistry journal Nanoscale. The scientists were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those “made” samples, two-dimensional magnesium oxide in bilayer graphene, Shahsavari says. “We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments,” Shahsavari says. Graphene on its own has no band gap — the characteristic that makes a material a semiconductor. But the hybrid does, and this band gap could be tunable, depending on the components, Shahsavari says. The enhanced optical properties are also tunable and useful, he says. “We saw that while this single flake of magnesium oxide absorbed one kind of light emission, when it was trapped between two layers of graphene, it absorbed a wide spectrum. That could be an important mechanism for sensors,” he says. Shahsavari says his group’s theory should be applicable to other two-dimensional materials, like hexagonal boron-nitride, and molecular fillings. “There is no single material that can solve all the technical problems of the world,” he says. “It always comes down to making hybrid materials to synergize the best features of multiple components to do a specific job. My group is working on these hybrid materials by tweaking their components and structures to meet new challenges.” Farzaneh Shayeganfar, a visiting research scientist at Rice and researcher at Shahid Rajaee Teacher Training University, Tehran, Iran, is lead author of the paper. Co-authors are Javad Beheshtiyan and Mehdi Neek-Amal, both of Shahid Rajaee and the University of Antwerp, Belgium. Rice University and the Iran Science Elites Federation supported the research. Computing resources were supplied by Rice’s National Science Foundation-supported DAVinCI supercomputer administered by Rice’s Center for Research Computing and were procured in partnership with Rice’s Ken Kennedy Institute for Information Technology.


News Article | February 15, 2017
Site: www.nature.com

Mathematicians say that they have solved a major, decades-old problem in geometry: how to reconstruct the inner structure of a mystery object ‘X’ from knowing only how fast waves travel between any two points on its boundary. The work has implications in real-world situations, such as for geophysicists who use seismic waves to analyse the structure of Earth’s interior. “Without destroying ‘X’, can we figure out what’s inside?” asked mathematician András Vasy of Stanford University in California, when he presented the work in a talk at University College London (UCL) last week. “One way to do it is to send waves through it,” he said, and measure their properties. Now, Vasy and two of his collaborators say that they have proved1 that this information alone is sufficient to reveal an object’s internal structure. The problem is called the boundary-rigidity conjecture. It belongs to the field of Riemannian geometry, the modern theory of curved spaces with any number of dimensions. Albert Einstein built his general theory of relativity — in which mass warps the geometry of space-time — on this branch of mathematics. Mathematicians already knew that the way in which curvature varies from place to place inside a ‘Riemannian manifold’ — the mathematical jargon for curved space — determines the shortest paths between any two points. The conjecture flips things around: it says that knowing the lengths of the shortest paths between points on a boundary essentially determines the curvature throughout. (The geometry is therefore said to be ‘rigid’.) Thus, by measuring how fast waves travel inside a space, one could work out the shortest paths, and theoretically, the overall structure. The conjecture dates back to at least 1981, when the late mathematician René Michel2 formulated certain technical assumptions about the spaces for which it should be true. (It is not true for Riemannian manifolds in general.) Vasy’s co-author Gunther Uhlmann, a mathematician at the University of Washington in Seattle, has been working on this problem since the late 1990s, and he and a collaborator had already solved it for two-dimensional Riemannian manifolds — that is, curved surfaces3. Now, Vasy, Uhlmann and Plamen Stefanov, who is at Purdue University in West Lafayette, Indiana, have solved it for spaces that have three or more dimensions, as well. In Einstein’s space-time, curvature produces gravitational lensing, a phenomenon familiar to astronomers, in which the path of light bends around massive objects such as stars. Similar mathematics apply to conventional lensing, or refraction: light rays or sound waves shift direction when the medium through which they are travelling changes. In the case of seismic waves — generated by events such as earthquakes — the differing properties of Earth at varying depths mean that the shortest path for such waves is usually not a straight line, but a curved one. Since the early 1900s, geophysicists have used this fact to map the planet’s internal structure, and this is how they discovered the mantle and the inner and outer cores. Those discoveries were rooted in mathematical treatments that had some simplifying assumptions. Until now, it was not clear that one could fully determine Earth’s structure using only wave travel times. But that is what Vasy and his team’s proof shows — and the geophysical problem was a key motivation for solving the conjecture. Their assumption, which differed from Michel’s, was that the curved space, or manifold, is structured with concentric layers. This allowed them to construct a solution in stages. “You go layer by layer, like peeling an onion,” says Uhlmann. For practical applications, this means that researchers will not only know that there is a unique solution to the problem; they will also have a procedure to calculate that solution explicitly. The three mathematicians circulated their 50-page paper among a small pool of experts and then posted it in the arXiv repository. Depending on the feedback they get, the authors hope to submit it to a journal in the coming weeks. Vasy says that the work could be helpful to people who develop medical-imaging techniques such as ultrasound, as well as to seismologists. But applying the theory to real geophysical data will not happen immediately, says Maarten de Hoop, a computational seismologist at Rice University in Houston, Texas. One difficulty is that the theory assumes that there is information at every point. But in reality, data are collected only at relatively sparse locations. Uhlmann says that he is working on that problem with colleagues who specialize in numerical analysis. The improved mathematical approach probably won’t drastically change our picture of Earth’s structure yet, says de Hoop. But it could lead to a better understanding of known features, such as the mantle plumes underneath Iceland or Hawaii, and perhaps, to the discovery of new ones, he says. As with every meaty mathematical result, “it will take a while to come to grips with it” and to vet the proof thoroughly, says Gabriel Paternain, a mathematician at the University of Cambridge, UK. Experts are taking the claim seriously, in part because it builds on a technical step from a linear form of the problem that the community had already accepted as a breakthrough4, adds UCL mathematician Yaroslav Kurylev. So far, says Paternain, the impression is “excellent”.


Home > Press > Graphene foam gets big and tough: Rice University's nanotube-reinforced material can be shaped, is highly conductive Abstract: A chunk of conductive graphene foam reinforced by carbon nanotubes can support more than 3,000 times its own weight and easily bounce back to its original height, according to Rice University scientists. Better yet, it can be made in just about any shape and size, they reported, demonstrating a screw-shaped piece of the highly conductive foam. The Rice lab of chemist James Tour tested its new "rebar graphene" as a highly porous, conductive electrode in lithium ion capacitors and found it to be mechanically and chemically stable. The research appears in the American Chemical Society journal ACS Applied Materials and Interfaces. Carbon in the form of atom-thin graphene is among the strongest materials known and is highly conductive; multiwalled carbon nanotubes are widely used as conductive reinforcements in metals, polymers and carbon matrix composites. The Tour lab had already used nanotubes to reinforce two-dimensional sheets of graphene. Extending the concept to macroscale materials made sense, Tour said. "We developed graphene foam, but it wasn't tough enough for the kind of applications we had in mind, so using carbon nanotubes to reinforce it was a natural next step," Tour said. The three-dimensional structures were created from a powdered nickel catalyst, surfactant-wrapped multiwall nanotubes and sugar as a carbon source. The materials were mixed and the water evaporated; the resulting pellets were pressed into a steel die and then heated in a chemical vapor deposition furnace, which turned the available carbon into graphene. After further processing to remove remnants of nickel, the result was an all-carbon foam in the shape of the die, in this case a screw. Tour said the method will be easy to scale up. Electron microscope images of the foam showed partially unzipped outer layers of the nanotubes had bonded to the graphene, which accounted for its strength and resilience. Graphene foam produced without the rebar could support only about 150 times its own weight while retaining the ability to rapidly return to its full height. But rebar graphene irreversibly deformed by about 25 percent when loaded with more than 8,500 times its weight. Junwei Sha, a visiting graduate student at Rice and a graduate student at Tianjin University, China, is lead author of the paper. Co-authors from Rice are postdoctoral researchers Rodrigo Salvatierra, Pei Dong and Yongsung Ji; graduate students Yilun Li, Tuo Wang, Chenhao Zhang and Jibo Zhang; former postdoctoral researcher Seoung-Ki Lee; Pulickel Ajayan, chair of the Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry; and Jun Lou, a professor of materials science and nanoengineering. Naiqin Zhao, a professor at Tianjin University and a researcher at the Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, is also a co-author. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice. The Air Force Office of Scientific Research and its Multidisciplinary University Research Initiative supported the research. About Rice University Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to http://tinyurl.com/RiceUniversityoverview . Follow Rice News and Media Relations via Twitter @RiceUNews For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Abstract: Rice University researchers have modeled a nanoscale sandwich, the first in what they hope will become a molecular deli for materials scientists. Their recipe puts two slices of atom-thick graphene around nanoclusters of magnesium oxide that give the super-strong, conductive material expanded optoelectronic properties. Rice materials scientist Rouzbeh Shahsavari and his colleagues built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis and bio-imaging. Their work could help researchers design a range of customizable hybrids of two- and three-dimensional structures with encapsulated molecules, Shahsavari said. The research appears this month in the Royal Society of Chemistry journal Nanoscale. The scientists were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those "made" samples, two-dimensional magnesium oxide in bilayer graphene, Shahsavari said. "We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments," Shahsavari said. Graphene on its own has no band gap - the characteristic that makes a material a semiconductor. But the hybrid does, and this band gap could be tunable, depending on the components, Shahsavari said. The enhanced optical properties are also tunable and useful, he said. "We saw that while this single flake of magnesium oxide absorbed one kind of light emission, when it was trapped between two layers of graphene, it absorbed a wide spectrum. That could be an important mechanism for sensors," he said. Shahsavari said his group's theory should be applicable to other two-dimensional materials, like hexagonal boron-nitride, and molecular fillings. "There is no single material that can solve all the technical problems of the world," he said. "It always comes down to making hybrid materials to synergize the best features of multiple components to do a specific job. My group is working on these hybrid materials by tweaking their components and structures to meet new challenges." ### Farzaneh Shayeganfar, a visiting research scientist at Rice and researcher at Shahid Rajaee Teacher Training University, Tehran, Iran, is lead author of the paper. Co-authors are Javad Beheshtiyan and Mehdi Neek-Amal, both of Shahid Rajaee and the University of Antwerp, Belgium. Rice University and the Iran Science Elites Federation supported the research. Computing resources were supplied by Rice's National Science Foundation-supported DAVinCI supercomputer administered by Rice's Center for Research Computing and were procured in partnership with Rice's Ken Kennedy Institute for Information Technology. About Rice University Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview . Follow Rice News and Media Relations via Twitter @RiceUNews For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Better yet, it can be made in just about any shape and size, they reported, demonstrating a screw-shaped piece of the highly conductive foam. The Rice lab of chemist James Tour tested its new "rebar graphene" as a highly porous, conductive electrode in lithium ion capacitors and found it to be mechanically and chemically stable. The research appears in the American Chemical Society journal ACS Applied Materials and Interfaces. Carbon in the form of atom-thin graphene is among the strongest materials known and is highly conductive; multiwalled carbon nanotubes are widely used as conductive reinforcements in metals, polymers and carbon matrix composites. The Tour lab had already used nanotubes to reinforce two-dimensional sheets of graphene. Extending the concept to macroscale materials made sense, Tour said. "We developed graphene foam, but it wasn't tough enough for the kind of applications we had in mind, so using carbon nanotubes to reinforce it was a natural next step," Tour said. The three-dimensional structures were created from a powdered nickel catalyst, surfactant-wrapped multiwall nanotubes and sugar as a carbon source. The materials were mixed and the water evaporated; the resulting pellets were pressed into a steel die and then heated in a chemical vapor deposition furnace, which turned the available carbon into graphene. After further processing to remove remnants of nickel, the result was an all-carbon foam in the shape of the die, in this case a screw. Tour said the method will be easy to scale up. Electron microscope images of the foam showed partially unzipped outer layers of the nanotubes had bonded to the graphene, which accounted for its strength and resilience. Graphene foam produced without the rebar could support only about 150 times its own weight while retaining the ability to rapidly return to its full height. But rebar graphene irreversibly deformed by about 25 percent when loaded with more than 8,500 times its weight. Junwei Sha, a visiting graduate student at Rice and a graduate student at Tianjin University, China, is lead author of the paper. Co-authors from Rice are postdoctoral researchers Rodrigo Salvatierra, Pei Dong and Yongsung Ji; graduate students Yilun Li, Tuo Wang, Chenhao Zhang and Jibo Zhang; former postdoctoral researcher Seoung-Ki Lee; Pulickel Ajayan, chair of the Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry; and Jun Lou, a professor of materials science and nanoengineering. Naiqin Zhao, a professor at Tianjin University and a researcher at the Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, is also a co-author. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice. Graphene foam invented at Rice University is reinforced with carbon nanotubes. It can hold thousands of times its own weight and still bounce back to its full height. Credit: Tour Group/Rice University Explore further: 'Rivet graphene' proves its mettle: Toughened material is easier to handle, useful for electronics


News Article | February 28, 2017
Site: www.rdmag.com

A group of researchers have concocted the perfect recipe for a nanoscale sandwich. Scientists from Rice University have put two slices of atom-thick graphene around nanoclusters of magnesium oxide to give a super-strong, conductive material of expanded optoelectronic properties. A team led by Rice materials scientist Rouzbeh Shahsavari built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis and bio-imaging. This new research could help researchers design a range of customizable hybrids of two and three-dimensional structures with encapsulated molecules. The researchers were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those “made” sample— two-dimensional magnesium oxide in bilayer graphene. “We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments,” Shahsavari said in a statement. Graphene on its own has no band gap—the characteristic that makes a material a semiconductor. However, the newly created hybrid does have a band gap that could be tunable, depending on the components. The enhanced optical properties are also tunable and useful. “We saw that while this single flake of magnesium oxide absorbed one kind of light emission, when it was trapped between two layers of graphene, it absorbed a wide spectrum,” Shahsavari said. “That could be an important mechanism for sensors.” According to Shahsavari, the group’s theory should be applicable to other two-dimensional materials, including hexagonal boron-nitride and molecular fillings. “There is no single material that can solve all the technical problems of the world,” he said. “It always comes down to making hybrid materials to synergize the best features of multiple components to do a specific job. “My group is working on these hybrid materials by tweaking their components and structures to meet new challenges,” he added. The study was published in Nanoscale.


News Article | February 17, 2017
Site: www.futurity.org

Scientists discovered that a hemoglobin mutation was causing mild anemia in a young woman in Germany. But why did her father, who has the same mutation, not have anemia, too? The woman, who was in her 20s when diagnosed, and her father share a mutation in the gene that encodes hemoglobin, the protein in red blood cells responsible for taking up and delivering oxygen to cells around the body. The mutation is one of more than 1,000 discovered so far in adult human hemoglobin. Most appear to have no effect on people, but when medical problems occur, the disease is called a hemoglobinopathy and often named after the city or hospital where it was discovered. In this case, the family was living in Mannheim, Germany, but the father was born in the Turkish city of Kirklareli. The Kirklareli mutation did not affect the iron content of the father’s blood, but did appear to be the root cause of the young woman’s chronic anemia, researchers say. Further investigation revealed that he was a smoker—and his mutant hemoglobin was stabilized by carbon monoxide from the cigarettes he smoked. A paper on the research appears in the Journal of Biological Chemistry. The mutation is in the alpha subunit of human hemoglobin (H58L) and causes it to rapidly auto-oxidize, or rust, which causes the protein to fall apart, lose heme, and precipitate. As a result, the protein loses its ability to carry oxygen. Eventually, the red cells themselves become deformed and are destroyed, says John Olson, a biochemist at Rice University. Remarkably, this same mutation gives the protein an 80,000-fold higher affinity for carbon monoxide than for oxygen. Carbon monoxide from a cigarette will be selectively taken up by the mutant hemoglobin and prevent it from oxidizing and denaturing. This high affinity for carbon monoxide explained why the father showed no signs of anemia, Olson says. “He may never be an athlete because his blood can’t carry as much oxygen, but smoking has prevented him from being anemic. And there’s a side benefit. People with this trait are more resistant to carbon monoxide poisoning.” Olson says he does not know how or if the doctors treated the young woman. He doesn’t even know her name. But he suspected her iron-deficient anemia was more an annoyance than a threat to her life and would not recommend she start smoking to relieve it. “She shouldn’t smoke,” he says. “But she could take antioxidants, such as a lot of vitamin C, which would help prevent oxidation of her mutant hemoglobin. Her anemia is not that severe. At the same time, she shouldn’t worry too much about secondhand smoke, which might have a positive effect.” After ruling out common causes like blood loss, gastritis, or congenital defects, her doctors were curious enough about her ailment to call upon Emmanuel Bissé, a researcher at the Institute for Clinical Chemistry and Laboratory Medicine at the University of Freiburg, who discovered the mutation after sequencing her DNA. Bissé in turn recruited Olson and his team to help determine why the histidine-to-leucine change caused anemia in the daughter but not the father. Ironically, Ivan Birukou, a graduate student in Olson’s lab, had already generated the same mutation in human hemoglobin (one of several hundred made at Rice) to study how the protein rapidly and selectively binds oxygen. “Emmanuel wrote to me and said, ‘I know you’ve been making all these mutants in hemoglobin, and you’ve probably done the H58L mutation in (alpha) chains. Does this phenotype make sense?'” Olson recalls. “I said, ‘We can do a really neat study here, because we’ve already made the mutant hemoglobin in a recombinant system.’ We actually had a crystal structure (matching Kirklareli) that Ivan and (staff scientist) Jayashree Soman never published but had deposited in the Protein Data Bank. We had made this mutation to try to understand what the distal histidine was doing in alpha subunits.” They found in their 2010 study that replacing the histidine, which forms a strong hydrogen bond to oxygen, with leucine caused a dramatic decrease in oxygen affinity and an increase in carbon monoxide binding. Olson and Birukou realized back then that histidine played a key role in discriminating between oxygen and carbon monoxide in hemoglobin. “When Emmanuel wrote to me about his discovery, I already ‘knew’ what was happening with respect to carbon monoxide binding,” Olson says. The normal hydrogen bond causes bound oxygen to stick more tightly to hemoglobin in the same way hydrogen bonds cause spilled soda to feel sticky. “When you touch it, the sugar oxygens and hydrogens make hydrogen bonds with the polysaccharides on your finger,” Olson said. “That stickiness helps hold onto oxygen. But leucine is more like an oil, like butane or hexane, and oxygen does not stick well inside hemoglobin. In contrast, bound carbon monoxide is more like methane or ethane and can’t form hydrogen bonds.” Andres Benitez Cardenas, a postdoctoral researcher in Olson’s laboratory, did the crucial experiment in which he put carbon monoxide on the mutant alpha subunit of hemoglobin Kirklareli. The bound carbon monoxide slowed down oxidation of the protein and prevented loss of heme and precipitation. “In effect, Andres did the ‘smoking experiment’ to show why the father’s hemoglobin didn’t denature and cause anemia,” Olson said. The effect caused by Kirklareli, though unusual, is not unique. “There is another ‘smoking is good for you’ mutation,” he says, noting discoveries in Zurich in the late 1970s and early ’80s. That case mirrored the current collaboration, as the researchers looking for answers then sought help from Nobel Laureate Max Perutz, whose pioneering work on hemoglobin structures won him the prize in 1968. Olson himself served as a reviewer on some of the papers for hemoglobin Zurich in the 1980s. “Emmanuel knew that we had worked on these histidine-to-leucine mutations in myoglobin and hemoglobin, which is why he contacted us,” he says. “This type of collaboration is how science and medicine should work together.” Additional researchers from Rice, the University of Freiburg, and the University of Strasbourg are coauthors of the work.


News Article | February 14, 2017
Site: www.cemag.us

A chunk of conductive graphene foam reinforced by carbon nanotubes can support more than 3,000 times its own weight and easily bounce back to its original height, according to Rice University scientists. Better yet, it can be made in just about any shape and size, they report, demonstrating a screw-shaped piece of the highly conductive foam. The Rice lab of chemist James Tour tested its new “rebar graphene” as a highly porous, conductive electrode in lithium ion capacitors and found it to be mechanically and chemically stable. The research appears in the American Chemical Society journal ACS Applied Materials and Interfaces. Carbon in the form of atom-thin graphene is among the strongest materials known and is highly conductive; multiwalled carbon nanotubes are widely used as conductive reinforcements in metals, polymers and carbon matrix composites. The Tour lab had already used nanotubes to reinforce two-dimensional sheets of graphene. Extending the concept to macroscale materials made sense, Tour said. “We developed graphene foam, but it wasn’t tough enough for the kind of applications we had in mind, so using carbon nanotubes to reinforce it was a natural next step,” Tour says.


News Article | February 28, 2017
Site: www.cemag.us

Rice University researchers have modeled a nanoscale sandwich, the first in what they hope will become a molecular deli for materials scientists. Their recipe puts two slices of atom-thick graphene around nanoclusters of magnesium oxide that give the super-strong, conductive material expanded optoelectronic properties. Rice materials scientist Rouzbeh Shahsavari and his colleagues built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis, and bio-imaging. Their work could help researchers design a range of customizable hybrids of two- and three-dimensional structures with encapsulated molecules, Shahsavari said. The research appears this month in the Royal Society of Chemistry journal Nanoscale. The scientists were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those “made” samples, two-dimensional magnesium oxide in bilayer graphene, Shahsavari says. “We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments,” Shahsavari says. Graphene on its own has no band gap — the characteristic that makes a material a semiconductor. But the hybrid does, and this band gap could be tunable, depending on the components, Shahsavari says. The enhanced optical properties are also tunable and useful, he says. “We saw that while this single flake of magnesium oxide absorbed one kind of light emission, when it was trapped between two layers of graphene, it absorbed a wide spectrum. That could be an important mechanism for sensors,” he says. Shahsavari says his group’s theory should be applicable to other two-dimensional materials, like hexagonal boron-nitride, and molecular fillings. “There is no single material that can solve all the technical problems of the world,” he says. “It always comes down to making hybrid materials to synergize the best features of multiple components to do a specific job. My group is working on these hybrid materials by tweaking their components and structures to meet new challenges.” Farzaneh Shayeganfar, a visiting research scientist at Rice and researcher at Shahid Rajaee Teacher Training University, Tehran, Iran, is lead author of the paper. Co-authors are Javad Beheshtiyan and Mehdi Neek-Amal, both of Shahid Rajaee and the University of Antwerp, Belgium. Rice University and the Iran Science Elites Federation supported the research. Computing resources were supplied by Rice’s National Science Foundation-supported DAVinCI supercomputer administered by Rice’s Center for Research Computing and were procured in partnership with Rice’s Ken Kennedy Institute for Information Technology.


Stevenson P.M.,Rice University
Nuclear Physics B | Year: 2013

Perturbative QCD, when optimized by the principle of minimal sensitivity at fourth order, yields finite results for Re+e-(Q) down to Q=0. For two massless flavors (nf=2) this occurs because the couplant "freezes" at a fixed-point of the optimized β function. However, for larger nf's, between 6.7 and 15.2, the infrared limit arises by a novel mechanism in which the evolution of the optimized β function with energy Q is crucial. The evolving β function develops a minimum that, as Q→0, just touches the axis at ap (the "pinch point"), while the infrared limit of the optimized couplant is at a larger value, a{star operator} (the "unfixed point"). This phenomenon results in R approaching its infrared limit not as a power law, but as R→R{star operator}-const/|lnQ|2. Implications for the phase structure of QCD as a function of nf are briefly considered. © 2013 Elsevier B.V.


Stevenson P.M.,Rice University
Nuclear Physics B | Year: 2013

Physical quantities in QCD are independent of renormalization scheme (RS), but that exact invariance is spoiled by truncations of the perturbation series. "Optimization" corresponds to making the perturbative approximant, at any given order, locally invariant under small RS changes. A solution of the resulting optimization equations is presented. It allows an efficient algorithm for finding the optimized result. Example results for Re+e-=3∑qi2(1+R) to fourth order (NNNLO) are given that show nice convergence, even down to arbitrarily low energies. The Q=. 0 "freezing" behavior, R=0.3±0.3, found at third order is confirmed and made more precise; R=0.2±0.1. Low-energy results in the MS- scheme, by contrast, show the typical pathologies of a non-convergent asymptotic series. © 2012 Elsevier B.V.


He J.,Rice University | Deem M.W.,Rice University
Physical Review Letters | Year: 2010

Clustered regularly interspaced short palindromic repeats (CRISPR) in bacterial and archaeal DNA have recently been shown to be a new type of antiviral immune system in these organisms. We here study the diversity of spacers in CRISPR under selective pressure. We propose a population dynamics model that explains the biological observation that the leader-proximal end of CRISPR is more diversified and the leader-distal end of CRISPR is more conserved. This result is shown to be in agreement with recent experiments. Our results show that the CRISPR spacer structure is influenced by and provides a record of the viral challenges that bacteria face. © 2010 The American Physical Society.


Liu Y.,Rice University | Dobrinsky A.,Rice University | Yakobson B.I.,Rice University
Physical Review Letters | Year: 2010

The energy of an arbitrary graphene edge, from armchair (A) to zigzag (Z) orientation, is derived in analytical form. It contains a "chemical phase shift" determined by the chemical conditions at the edge. Direct atomistic computations support the universal nature of the relationship, definitive for graphene formation, and shapes of the voids or ribbons. It has further profound implications for nanotube chirality selection and possibly control by chemical means, at the nucleation stage. © 2010 The American Physical Society.


He J.,Rice University | Deem M.W.,Rice University
Physical Review Letters | Year: 2010

We examine how the structure of the world trade network has been shaped by globalization and recessions over the last 40 years. We show that by treating the world trade network as an evolving system, theory predicts the trade network is more sensitive to recessionary shocks and recovers more slowly from them now than it did 40 years ago, due to structural changes in the world trade network induced by globalization. We also show that recession-induced change to the world trade network leads to an increased hierarchical structure of the global trade network for a few years after the recession. © 2010 The American Physical Society.


Crawford K.M.,Rice University | Whitney K.D.,Rice University
Molecular Ecology | Year: 2010

Much thought has been given to the individual-level traits that may make a species a successful colonizer. However, these traits have proven to be weak predictors of colonization success. Here, we test whether population-level characteristics, specifically genetic diversity and population density, can influence colonization ability on a shortterm ecological timescale, independent of longer-term effects on adaptive potential. Within experimentally manipulated populations of the weedy herb Arabidopsis thaliana, we found that increased genetic diversity increased colonization success measured as population-level seedling emergence rates, biomass production, flowering duration, and reproduction. Additive and non-additive effects contributed to these responses, suggesting that both individual genotypes (sampling effect) and positive interactions among genotypes (complementarity) contributed to increased colonization success. In contrast, manipulation of plant density had no effect on colonization success. The heightened ability of relatively genetically rich populations to colonize novel habitats, if a general phenomenon, may have important implications for predicting and controlling biological invasions. © 2010 Blackwell Publishing Ltd.


Kougioumtzoglou I.A.,University of Liverpool | Spanos P.D.,Rice University
Computers and Structures | Year: 2013

An approximate analytical dimension reduction approach is developed for determining the response of a multi-degree-of-freedom (MDOF) nonlinear/hysteretic system subject to a non-stationary stochastic excitation vector. The approach is based on the concepts of statistical linearization and of stochastic averaging. It is readily applicable even for excitations possessing evolutionary in time power spectra. Further, it can be potentially used in conjunction with design spectrum based analyses to obtain peak system response estimates. Numerical examples include MDOF systems comprising the versatile Bouc-Wen (hysteretic) model. The reliability of the approach is demonstrated by pertinent Monte Carlo simulations. © 2012 Elsevier Ltd.


Zhu Y.,Rice University | Tour J.M.,Rice University
Nano Letters | Year: 2010

Described here is a room temperature procedure to fabricate graphene nanoribbon (GNR) thin films. The GNRs, synthesized by unzipping carbon nanotubes, were reduced and functionalized. The functionalized GNRs are negatively or positively charged, which are suitable to assemble thin films by electrostatic layer-by-layer absorption. The homogenous full GNR films were fabricated on various substrates with controllable thicknesses. By assembling the GNRs films on silicon oxide/silicon surfaces, bottom-gated GNR thin-film transistors were fabricated in a solution processed technique. © 2010 American Chemical Society.


Halas N.J.,Rice University
Nano Letters | Year: 2010

While studies of surface plasmons on metals have been pursued for decades, the more recent appearance of nanoscience has created a revolution in this field with "Plasmonics" emerging as a major area of research. The direct optical excitation of surface plasmons on metallic nanostructures provides numerous ways to control and manipulate light at nanoscale dimensions. This has stimulated the development of novel optical materials, deeper theoretical insight, innovative new devices, and applications with potential for significant technological and societal impact. Nano Letters has been instrumental in the emergence of plasmonics, providing its readership with rapid advances in this dynamic field. © 2010 American Chemical Society.


Whitford P.C.,Rice University | Sanbonmatsu K.Y.,Los Alamos National Laboratory | Onuchic J.N.,Rice University
Reports on Progress in Physics | Year: 2012

While the energy landscape theory of protein folding is now a widely accepted view for understanding how relatively weak molecular interactions lead to rapid and cooperative protein folding, such a framework must be extended to describe the large-scale functional motions observed in molecular machines. In this review, we discuss (1) the development of the energy landscape theory of biomolecular folding, (2) recent advances toward establishing a consistent understanding of folding and function and (3) emerging themes in the functional motions of enzymes, biomolecular motors and other biomolecular machines. Recent theoretical, computational and experimental lines of investigation have provided a very dynamic picture of biomolecular motion. In contrast to earlier ideas, where molecular machines were thought to function similarly to macroscopic machines, with rigid components that move along a few degrees of freedom in a deterministic fashion, biomolecular complexes are only marginally stable. Since the stabilizing contribution of each atomic interaction is on the order of the thermal fluctuations in solution, the rigid body description of molecular function must be revisited. An emerging theme is that functional motions encompass orderdisorder transitions and structural flexibility provides significant contributions to the free energy. In this review, we describe the biological importance of orderdisorder transitions and discuss the statisticalmechanical foundation of theoretical approaches that can characterize such transitions. © 2012 IOP Publishing Ltd.


Yan Z.,Rice University | Peng Z.,Rice University | Tour J.M.,Rice University
Accounts of Chemical Research | Year: 2014

As a two-dimensional (2D) sp2-bonded carbon allotrope, graphene has attracted enormous interest over the past decade due to its unique properties, such as ultrahigh electron mobility, uniform broadband optical absorption and high tensile strength. In the initial research, graphene was isolated from natural graphite, and limited to small sizes and low yields. Recently developed chemical vapor deposition (CVD) techniques have emerged as an important method for the scalable production of large-size and high-quality graphene for various applications. However, CVD-derived graphene is polycrystalline and demonstrates degraded properties induced by grain boundaries. Thus, the next critical step of graphene growth relies on the synthesis of large graphene single crystals.In this Account, we first discuss graphene grain boundaries and their influence on graphene's properties. Mechanical and electrical behaviors of CVD-derived polycrystalline graphene are greatly reduced when compared to that of exfoliated graphene. We then review four representative pathways of pretreating Cu substrates to make millimeter-sized monolayer graphene grains: electrochemical polishing and high-pressure annealing of Cu substrate, adding of additional Cu enclosures, melting and resolidfying Cu substrates, and oxygen-rich Cu substrates. Due to these pretreatments, the nucleation site density on Cu substrates is greatly reduced, resulting in hexagonal-shaped graphene grains that show increased grain domain size and comparable electrical properties as to exfoliated graphene. Also, the properties of graphene can be engineered by its shape, thickness and spatial structure. Thus, we further discuss recently developed methods of making graphene grains with special spatial structures, including snowflakes, six-lobed flowers, pyramids and hexagonal graphene onion rings. The fundamental growth mechanism and practical applications of these well-shaped graphene structures should be interesting topics and deserves more attention in the near future. Following that, recent efforts in fabricating large single-crystal monolayer graphene on other metal substrates, including Ni, Pt, and Ru, are also described. The differences in growth conditions reveal different growth mechanisms on these metals. Another key challenge for graphene growth is to make graphene single crystals on insulating substrates, such as h-BN, SiO 2, and ceramic. The recently developed plasma-enhanced CVD method can be used to directly synthesize graphene single crystals on h-BN substrates and is described in this Account as well.To summarize, recent research in synthesizing millimeter-sized monolayer graphene grains with different pretreatments, graphene grain shapes, metal catalysts, and substrates is reviewed. Although great advancements have been achieved in CVD synthesis of graphene single crystals, potential challenges still exist, such as the growth of wafer-sized graphene single crystals to further facilitate the fabrication of graphene-based devices, as well as a deeper understanding of graphene growth mechanisms and growth dynamics in order to make graphene grains with precisely controlled thicknesses and spatial structures. © 2014 American Chemical Society.


Karl N.J.,Rice University
Nature Photonics | Year: 2015

The idea of using radiation in the 0.1–1.0 THz range as carrier waves for free-space wireless communications has attracted growing interest in recent years, due to the promise of the large available bandwidth. Recent research has focused on system demonstrations, as well as the exploration of new components for modulation, beam steering and polarization control. However, the multiplexing and demultiplexing of terahertz signals remains an unaddressed challenge, despite the importance of such capabilities for broadband networks. Using a leaky-wave antenna based on a metal parallel-plate waveguide, we demonstrate frequency-division multiplexing and demultiplexing over more than one octave of bandwidth. We show that this device architecture offers a unique method for controlling the spectrum allocation, by variation of the waveguide plate separation. This strategy, which is distinct from those previously employed in either the microwave or optical regimes, enables independent control of both the centre frequency and bandwidth of multiplexed terahertz channels. © 2015 Nature Publishing Group


Ouyang M.,Huazhong University of Science and Technology | Duenas-Osorio L.,Rice University
Structural Safety | Year: 2014

Electric power systems are critical to economic prosperity, national security, public health and safety. However, in hurricane-prone areas, a severe storm may simultaneously cause extensive component failures in a power system and lead to cascading failures within it and across other power-dependent utility systems. Hence, the hurricane resilience of power systems is crucial to ensure their rapid recovery and support the needs of the population in disaster areas. This paper introduces a probabilistic modeling approach for quantifying the hurricane resilience of contemporary electric power systems. This approach includes a hurricane hazard model, component fragility models, a power system performance model, and a system restoration model. These coupled four models enable quantifying hurricane resilience and estimating economic losses. Taking as an example the power system in Harris County, Texas, USA, along with real outage and restoration data after Hurricane Ike in 2008, the proposed resilience assessment model is calibrated and verified. In addition, several dimensions of resilience as well as the effectiveness of alternative strategies for resilience improvement are simulated and analyzed. Results show that among technical, organizational and social dimensions of resilience, the organizational resilience is the highest with a value of 99.964% (3.445 in a proposed logarithmic scale) while the social resilience is the lowest with a value of 99.760% (2.620 in the logarithmic scale). Although these values seem high in absolute terms due to the reliability of engineered systems, the consequences of departing from ideal resilience are still high as economic losses can add up to $83 million per year. © 2014 Elsevier Ltd.


Munoz E.,Rice University | Lu J.,Rice University | Yakobson B.I.,Rice University
Nano Letters | Year: 2010

An elastic-shell-based theory for calculating the thermal conductance of graphene ribbons of arbitrary width w is presented. The analysis of vibrational modes of a continuum thin plate leads to a general equation for ballistic conductanceσ. At low temperature, it yields a power law σ ∼ Tβ, where the exponent β varies with the ribbon width w from β = 1 for a narrow ribbon (σ∼ T, as a four-channel quantum wire) to β = 3/2 (σ∼ wT3/2) in the limit of wider graphene sheets. The ballistic results can be augmented by the phenomenological value of a phonon mean free path to account for scattering and agree well with the reported experimental observations. © 2010 American Chemical Society.


Liu Y.,Rice University | Yakobson B.I.,Rice University
Nano Letters | Year: 2010

A polycrystalline graphene consists of perfect domains tilted at angle α to each other and separated by the grain boundaries (GB). These nearly one-dimensional regions consist in turn of elementary topological defects, 5-pentagons and 7-heptagons, often paired up into 5-7 dislocations. Energy G(α) of GB computed for all range 0 ≤ α ≤ π/3, shows a slightly asymmetric behavior, reaching ∼5 eV/nm in the middle, where the 5′s and 7′s qualitatively reorganize in transition from nearly armchair to zigzag interfaces. Analysis shows that two-dimensional (2D) nature permits the off-plane relaxation, unavailable in three-dimensional (3D) materials, qualitatively reducing the energy of defects on one hand while forming stable 3D landscapes on the other. Interestingly, while the GB display small off-plane elevation, the random distributions of 5′s and 7′s create roughness that scales inversely with defect concentration, h ∼ n -1/2. © 2010 American Chemical Society.


Background: Vascular endothelial cells (ECs) express and release protein components of the complement pathways, as well as secreting and anchoring ultra-large von Willebrand factor (ULVWF) multimers in long string-like structures that initiate platelet adhesion during hemostasis and thrombosis. The alternative complement pathway (AP) is an important non-antibody-requiring host defense system. Thrombotic microangiopathies can be associated with defective regulation of the AP (atypical hemolytic-uremic syndrome) or with inadequate cleavage by ADAMTS-13 of ULVWF multimeric strings secreted by/anchored to ECs (thrombotic thrombocytopenic purpura). Our goal was to determine if EC-anchored ULVWF strings caused the assembly and activation of AP components, thereby linking two essential defense mechanisms. Methodology/Principal Findings: We quantified gene expression of these complement components in cultured human umbilical vein endothelial cells (HUVECs) by real-time PCR: C3 and C5; complement factor (CF) B, CFD, CFP, CFH and CFI of the AP; and C4 of the classical and lectin (but not alternative) complement pathways. We used fluorescent microscopy, monospecific antibodies against complement components, fluorescent secondary antibodies, and the analysis of >150 images to quantify the attachment of HUVEC-released complement proteins to ULVWF strings secreted by, and anchored to, the HUVECs (under conditions of ADAMTS-13 inhibition). We found that HUVEC-released C4 did not attach to ULVWF strings, ruling out activation of the classical and lectin pathways by the strings. In contrast, C3, FB, FD, FP and C5, FH and FI attached to ULVWF strings in quantitative patterns consistent with assembly of the AP components into active complexes. This was verified when non-functional FB blocked the formation of AP C3 convertase complexes (C3bBb) on ULVWF strings. Conclusions/Significance: AP components are assembled and activated on EC-secreted/anchored ULVWF multimeric strings. Our findings provide one possible molecular mechanism for clinical linkage between different types of thrombotic and complement-mediated disorders. © 2013 Turner, Moake.


Ray J.C.J.,Rice University | Igoshin O.A.,Rice University
PLoS Computational Biology | Year: 2010

A widespread mechanism of bacterial signaling occurs through two-component systems, comprised of a sensor histidine kinase (SHK) and a transcriptional response regulator (RR). The SHK activates RR by phosphorylation. The most common two-component system structure involves expression from a single operon, the transcription of which is activated by its own phosphorylated RR. The role of this feedback is poorly understood, but it has been associated with an overshooting kinetic response and with fast recovery of previous interrupted signaling events in different systems. Mathematical models show that overshoot is only attainable with negative feedback that also improves response time. Our models also predict that fast recovery of previous interrupted signaling depends on high accumulation of SHK and RR, which is more likely in a positive feedback regime. We use Monte Carlo sampling of the parameter space to explore the range of attainable model behaviors. The model predicts that the effective feedback sign can change from negative to positive depending on the signal level. Variations in two-component system architectures and parameters may therefore have evolved to optimize responses in different bacterial lifestyles. We propose a conceptual model where low signal conditions result in a responsive system with effectively negative feedback while high signal conditions with positive feedback favor persistence of system output. © 2010 Ray, Igoshin.


Schlather A.E.,Rice University | Large N.,Rice University | Urban A.S.,Rice University | Nordlander P.,Rice University | Halas N.J.,Rice University
Nano Letters | Year: 2013

Strong coupling between resonantly matched localized surface plasmons and molecular excitons results in the formation of new hybridized energy states called plexcitons. Understanding the nature and tunability of these hybrid nanostructures is important for both fundamental studies and the development of new applications. We investigate the interactions between J-aggregate excitons and single plasmonic dimers and report for the first time a unique strong coupling regime in individual plexcitonic nanostructures. Dark-field scattering measurements and finite-difference time-domain simulations of the hybrid nanostructures show strong plexcitonic coupling mediated by the near-field inside each dimer gap, which can be actively controlled by rotating the polarization of the optical excitation. The plexciton dispersion curves, obtained from coupled harmonic oscillator models, show anticrossing behavior at the exciton transition energy and giant Rabi splitting ranging between 230 and 400 meV. These energies are, to the best of our knowledge, the largest obtained on individual hybrid nanostructures. © 2013 American Chemical Society.


Zuloaga J.,Rice University | Nordlander P.,Rice University
Nano Letters | Year: 2011

The localized plasmons of metallic nanoparticles and nanostructures are known to display an interesting and apparently universal phenomenon: upon optical excitation, the maximum near-field enhancements occur at lower energies than the maximum of the corresponding far-field spectrum. Here we present an explanation for this behavior, showing that it results directly from the physics of a driven and damped harmonic oscillator. We show that the magnitude of the shift between the near- and far-field peak intensities depends directly on the total damping of the system, whether it is intrinsic damping within the metal of the nanoparticle or radiative damping of the localized plasmon. © 2011 American Chemical Society.


Goldman R.,Rice University
Graphical Models | Year: 2011

Quaternion multiplication can be applied to rotate vectors in 3-dimensions. Therefore in Computer Graphics, quaternions are sometimes used in place of matrices to represent rotations in 3-dimensions. Yet while the formal algebra of quaternions is well-known in the Graphics community, the derivations of the formulas for this algebra and the geometric principles underlying this algebra are not well understood. The goals of this paper are: To provide a fresh, geometric interpretation of quaternions, appropriate for contemporary Computer Graphics;To derive the formula for quaternion multiplication from first principles;To present better ways to visualize quaternions, and the effect of quaternion multiplication on points and vectors in 3-dimensions based on insights from the algebra and geometry of multiplication in the complex plane;To develop simple, intuitive proofs of the sandwiching formulas for rotation and reflection;To show how to apply sandwiching to compute perspective projections. In Part I of this paper, we investigate the algebra of quaternion multiplication and focus in particular on topics i and ii. In Part II we apply our insights from Part I to analyze the geometry of quaternion multiplication with special emphasis on topics iii, iv and v. © 2010 Elsevier Inc. All rights reserved.


Wickham H.,Rice University
Journal of Statistical Software | Year: 2011

Many data analysis problems involve the application of a split-apply-combine strategy, where you break up a big problem into manageable pieces, operate on each piece inde- pendently and then put all the pieces back together. This insight gives rise to a new R package that allows you to smoothly apply this strategy, without having to worry about the type of structure in which your data is stored. The paper includes two case studies showing how these insights make it easier to work with batting records for veteran baseball players and a large 3d array of spatio-temporal ozone measurements.


Manjavacas A.,CSIC - Institute of Optics | Abajo F.J.G.D.,CSIC - Institute of Optics | Nordlander P.,Rice University
Nano Letters | Year: 2011

We present a fully quantum mechanical approach to describe the coupling between plasmons and excitonic systems such as molecules or quantum dots. The formalism relies on Zubarev's Green functions, which allow us to go beyond the perturbative regime within the internal evolution of a plasmonic nanostructure and to fully account for quantum aspects of the optical response and Fano resonances in plasmon - excition (plexcitonic) systems. We illustrate this method with two examples consisting of an exciton-supporting quantum emitter placed either in the vicinity of a single metal nanoparticle or in the gap of a nanoparticle dimer. The optical absorption of the combined emitter - dimer structure is shown to undergo dramatic changes when the emitter excitation level is tuned across the gap-plasmon resonance. Our work opens a new avenue to deal with strongly interacting plasmon - excition hybrid systems. © 2011 American Chemical Society.


Miller J.S.,Rice University
PLoS Biology | Year: 2014

How structure relates to function-across spatial scales, from the single molecule to the whole organism-is a central theme in biology. Bioengineers, however, wrestle with the converse question: will function follow form? That is, we struggle to approximate the architecture of living tissues experimentally, hoping that the structure we create will lead to the function we desire. A new means to explore the relationship between form and function in living tissue has arrived with three-dimensional printing, but the technology is not without limitations. © 2014 Jordan S.


Klimchuk J.A.,NASA | Bradshaw S.J.,Rice University
Astrophysical Journal | Year: 2014

It has been suggested that the hot plasma of the solar corona comes primarily from impulsive heating events, or nanoflares, that occur in the lower atmosphere, either in the upper part of the ordinary chromosphere or at the tips of type II spicules. We test this idea with a series of hydrodynamic simulations. We find that synthetic Fe XII (195) and Fe XIV (274) line profiles generated from the simulations disagree dramatically with actual observations. The integrated line intensities are much too faint; the blueshifts are much too fast; the blue-red asymmetries are much too large; and the emission is confined to low altitudes. We conclude that chromospheric nanoflares are not a primary source of hot coronal plasma. Such events may play an important role in producing the chromosphere and powering its intense radiation, but they do not, in general, raise the temperature of the plasma to coronal values. Those cases where coronal temperatures are reached must be relatively uncommon. The observed profiles of Fe XII and Fe XIV come primarily from plasma that is heated in the corona itself, either by coronal nanoflares or a quasi-steady coronal heating process. Chromospheric nanoflares might play a role in generating waves that provide this coronal heating. © 2014. The American Astronomical Society. All rights reserved..


Cech E.A.,Rice University
Science Technology and Human Values | Year: 2014

Much has been made of the importance of training ethical, socially conscious engineers, but does US engineering education actually encourage neophytes to take seriously their professional responsibility to public welfare? Counter to such ideals of engagement, I argue that students' interest in public welfare concerns may actually decline over the course of their engineering education. Using unique longitudinal survey data of students at four colleges, this article examines (a) how students' public welfare beliefs change during their engineering education, (b) whether engineering programs emphasize engagement, and (c) whether these program emphases are related to students' public welfare beliefs. I track four specific public welfare considerations: the importance to students of professional/ethical responsibilities, understanding the consequences of technology, understanding how people use machines, and social consciousness. Suggesting a culture of disengagement, I find that the cultural emphases of students' engineering programs are directly related to their public welfare commitments and students' public welfare concerns decline significantly over the course of their engineering education. However, these findings also suggest that if engineering programs can dismantle the ideological pillars of disengagement in their local climates, they may foster more engaged engineers. © The Author(s) 2013.


Everett E.,Rice University | Sahai A.,Rice University | Sabharwal A.,Rice University
IEEE Transactions on Wireless Communications | Year: 2014

Recent research results have demonstrated the feasibility of full-duplex wireless communication for short-range links. Although the focus of the previous works has been active cancellation of the self-interference signal, a majority of the overall self-interference suppression is often due to passive suppression, i.e., isolation of the transmit and receive antennas. We present a measurement-based study of the capabilities and limitations of three key mechanisms for passive self-interference suppression: directional isolation, absorptive shielding, and cross-polarization. The study demonstrates that more than 70 dB of passive suppression can be achieved in certain environments, but also establishes two results on the limitations of passive suppression: (1) environmental reflections limit the amount of passive suppression that can be achieved, and (2) passive suppression, in general, increases the frequency selectivity of the residual self-interference signal. These results suggest two design implications: (1) deployments of full-duplex infrastructure nodes should minimize near-antenna reflectors, and (2) active cancellation in concatenation with passive suppression should employ higher-order filters or per-subcarrier cancellation. © 2002-2012 IEEE.


Hoffmann J.C.,Rice University
Integrative biology : quantitative biosciences from nano to macro | Year: 2013

In order to independently study the numerous variables that influence cell movement, it will be necessary to employ novel tools and materials that allow for exquisite control of the cellular microenvironment. In this work, we have applied advanced 3D micropatterning technology, known as two-photon laser scanning lithography (TP-LSL), to poly(ethylene glycol) (PEG) hydrogels modified with bioactive peptides in order to fabricate precisely designed microenvironments to guide and quantitatively investigate cell migration. Specifically, TP-LSL was used to fabricate cell adhesive PEG-RGDS micropatterns on the surface of non-degradable PEG-based hydrogels (2D) and in the interior of proteolytically degradable PEG-based hydrogels (3D). HT1080 cell migration was guided down these adhesive micropatterns in both 2D and 3D, as observed via time-lapse microscopy. Differences in cell speed, cell persistence, and cell shape were observed based on variation of adhesive ligand, hydrogel composition, and patterned area for both 2D and 3D migration. Results indicated that HT1080s migrate faster and with lower persistence on 2D surfaces, while HT1080s migrating in 3D were smaller and more elongated. Further, cell migration was shown to have a biphasic dependence on PEG-RGDS concentration and cells moving within PEG-RGDS micropatterns were seen to move faster and with more persistence over time. Importantly, the work presented here begins to elucidate the multiple complex factors involved in cell migration, with typical confounding factors being independently controlled. The development of this unique platform will allow researchers to probe how cells behave within increasingly complex 3D microenvironments that begin to mimic specifically chosen aspects of the in vivo landscape.


Bradshaw S.J.,Rice University | Klimchuk J.A.,NASA
Astrophysical Journal, Supplement Series | Year: 2011

The "smoking gun" of small-scale, impulsive events heating the solar corona is expected to be the presence of hot (>5MK) plasma. Evidence for this has been scarce, but has gradually begun to accumulate due to recent studies designed to constrain the high-temperature part of the emission measure distribution. However, the detected hot component is often weaker than models predict and this is due in part to the common modeling assumption that the ionization balance remains in equilibrium. The launch of the latest generation of space-based observing instrumentation on board Hinode and the Solar Dynamics Observatory (SDO) has brought the matter of the ionization state of the plasma firmly to the forefront. It is timely to consider exactly what emission current instruments would detect when observing a corona heated impulsively on small scales by nanoflares. Only after we understand the full effects of nonequilibrium ionization can we draw meaningful conclusions about the plasma that is (or is not) present. We have therefore performed a series of hydrodynamic simulations for a variety of different nanoflare properties and initial conditions. Our study has led to several key conclusions. (1) Deviations from equilibrium are greatest for short-duration nanoflares at low initial coronal densities. (2) Hot emission lines are the most affected and are suppressed sometimes to the point of being invisible. (3) For the many scenarios we have considered, the emission detected in several of the SDO-AIA channels (131, 193, and 211 ) would be dominated by warm, overdense, cooling plasma. (4) It is difficult not to create coronal loops that emit strongly at 1.5MK and in the range 2-6MK, which are the most commonly observed kind, for a broad range of nanoflare scenarios. (5) The Fe XV (284.16 ) emission in most of our models is about 10 times brighter than the Ca XVII (192.82 ) emission, consistent with observations. Our overarching conclusion is that small-scale, impulsive heating inducing a nonequilibrium ionization state leads to predictions for observable quantities that are entirely consistent with what is actually observed. © 2011. The American Astronomical Society. All rights reserved..


Yu R.,Rice University | Si Q.,Rice University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

A U(1) slave-spin representation is introduced for multiorbital Hubbard models. As with the Z 2 form of de'Medici, this approach represents a physical electron operator as the product of a slave spin and an auxiliary fermion operator. For nondegenerate multiorbital models, our U(1) approach is advantageous in that it captures the noninteracting limit at the mean-field level. For systems with either a single orbital or degenerate multiple orbitals, the U(1) and Z 2 slave-spin approaches yield the same results in the slave-spin-condensed phase. In general, the U(1) slave-spin approach contains a U(1) gauge redundancy, and properly describes a Mott insulating phase. We apply the U(1) slave-spin approach to study the metal-to-insulator transition in a five-orbital model for parent iron pnictides. We demonstrate a Mott transition as a function of the interactions in this model. The nature of the Mott insulating state is influenced by the interplay between the Hund's rule coupling and crystal-field splittings. In the metallic phase, when the Hund's rule coupling is beyond a threshold, there is a crossover from a weakly correlated metal to a strongly correlated one, through which the quasiparticle spectral weight rapidly drops. The existence of such a strongly correlated metallic phase supports the incipient Mott picture of the parent iron pnictides. In the parameter regime for this phase and in the vicinity of the Mott transition, we find that an orbital selective Mott state has nearly as competitive a ground-state energy. © 2012 American Physical Society.


Lee C.-T.A.,Rice University | Luffi P.,Rice University | Chin E.J.,Rice University
Annual Review of Earth and Planetary Sciences | Year: 2011

Continents, especially their Archean cores, are underlain by thick thermal boundary layers that have been largely isolated from the convecting mantle over billion-year timescales, far exceeding the life span of oceanic thermal boundary layers. This longevity is promoted by the fact that continents are underlain by highly melt-depleted peridotites, which result in a chemically distinct boundary layer that is intrinsically buoyant and strong (owing to dehydration). This chemical boundary layer counteracts the destabilizing effect of the cold thermal state of continents. The compositions of cratonic peridotites require formation at shallower depths than they currently reside, suggesting that the building blocks of continents formed in oceanic or arc environments and became continental after significant thickening or underthrusting. Continents are difficult to destroy, but refertilization and rehydration of continental mantle by the passage of melts can nullify the unique stabilizing composition of continents. Copyright © 2011 by Annual Reviews. All rights reserved.


Halas N.J.,Rice University | Moskovits M.,University of California at Santa Barbara
MRS Bulletin | Year: 2013

Discovered by Richard Van Duyne in 1976, surface-enhanced Raman spectroscopy (SERS) has enjoyed a continual expansion in interest over the past 36 years benefitting from a series of discoveries, new fields, and technological capabilities, all of which have greatly contributed to the current broad interest in this topic. The focus on nanoscience and nanotechnology that began in the early 1990s naturally put a spotlight on SERS as a quintessentially nanoscale phenomenon. This article discusses some of the key field-shaping developments in SERS from a historical and a materials perspective, providing background for the articles in this issue of MRS Bulletin. Copyright © Materials Research Society 2013.


Hegde C.,Rice University | Baraniuk R.G.,Rice University
IEEE Transactions on Signal Processing | Year: 2011

Compressive sensing (CS) is a new technique for the efficient acquisition of signals, images and other data that have a sparse representation in some basis, frame, or dictionary. By sparse we mean that the N-dimensional basis representation has just K ≪ N significant coefficients; in this case, the CS theory maintains that just M = O(K log N) random linear signal measurements will both preserve all of the signal information and enable robust signal reconstruction in polynomial time. In this paper, we extend the CS theory to pulse stream data, which correspond to S-sparse signals/images that are convolved with an unknown F-sparse pulse shape. Ignoring their convolutional structure, a pulse stream signal is K=SF sparse. Such signals figure prominently in a number of applications, from neuroscience to astronomy. Our specific contributions are threefold. First, we propose a pulse stream signal model and show that it is equivalent to an infinite union of subspaces. Second, we derive a lower bound on the number of measurements M required to preserve the essential information present in pulse streams. The bound is linear in the total number of degrees of freedom S + F, which is significantly smaller than the nave bound based on the total signal sparsity K=SF. Third, we develop an efficient signal recovery algorithm that infers both the shape of the impulse response as well as the locations and amplitudes of the pulses. The algorithm alternatively estimates the pulse locations and the pulse shape in a manner reminiscent of classical deconvolution algorithms. Numerical experiments on synthetic and real data demonstrate the advantages of our approach over standard CS. © 2010 IEEE.


Engelhardt Jr. H.T.,Rice University
Journal of Medicine and Philosophy | Year: 2011

In the face of the moral pluralism that results from the death of God and the abandonment of a God's eye perspective in secular philosophy, bioethics arose in a context that renders it essentially incapable of giving answers to substantive moral questions, such as concerning the permissibility of abortion, human embryonic stem cell research, euthanasia, etc. Indeed, it is only when bioethics understands its own limitations and those of secular moral philosophy in general can it better appreciate those tasks that it can actually usefully perform in both the clinical and academic setting. It is the task of this paper to understand and reevaluate bioethics by understanding these limits. Academic bioethicists can analyze ideas, concepts, and claims necessary to understanding the moral questions raised in health care, assessing the arguments related to these issues, and provide an understanding of the different moral perspectives on bioethical issues. In the clinical setting, bioethicists can provide legal advice, serve as experts on IRBs, mediating disputes, facilitating decision-making and risk management, and clarifying normative issues. However, understanding this is only possible when one understands the history, genesis, and foundations of bioethics and its inability to provide a resolution to postmodern moral pluralism. © The Author 2011.


Autophagy reallocates nutrients and clears normal cells of damaged proteins and organelles. In the context of metastatic disease, invading cancer cells hijack autophagic processes to survive and adapt in the host microenvironment. We sought to understand how autophagy is regulated in the metastatic niche for prostate cancer (PCa) cells where bone marrow stromal cell (BMSC) paracrine signaling induces PCa neuroendocrine differentiation (NED). In PCa, this transdifferentiation of metastatic PCa cells to neuronal-like cells correlates with advanced disease. Because autophagy provides a survival advantage for cancer cells and promotes cell differentiation, we hypothesized that autophagy mediates PCa NED in the bone. Thus, we determined the ability of paracrine factors in conditioned media (CM) from two separate BMSC subtypes, HS5 and HS27a, to induce autophagy in C4-2 and C4-2B bone metastatic PCa cells by characterizing the autophagy marker, LC3. Unlike HS27a CM, HS5 CM induced LC3 accumulation in PCa cells, suggesting autophagy was induced and indicating that HS5 and HS27a secrete a different milieu of paracrine factors that influence PCa autophagy. We identified interleukin-6 (IL-6), a cytokine more highly expressed in HS5 cells than in HS27a cells, as a paracrine factor that regulates PCa autophagy. Pharmacological inhibition of STAT3 activity did not attenuate LC3 accumulation, implying that IL-6 regulates NED and autophagy through different pathways. Finally, chloroquine inhibition of autophagic flux blocked PCa NED; hence autophagic flux maintains NED. Our studies imply that autophagy is cytoprotective for PCa cells in the bone, thus targeting autophagy is a potential therapeutic strategy. © 2012 Landes Bioscience.


Vigderman L.,Rice University | Zubarev E.R.,Rice University
Langmuir | Year: 2012

Recently, branched and star-shaped gold nanoparticles have received significant attention for their unique optical and electronic properties, but most examples of such nanoparticles have a zero-dimensional shape with varying numbers of branches coming from a quasi-spherical core. This report details the first examples of higher-order penta-branched gold particles including rod-, wire-, and platelike particles which contain a uniquely periodic starfruitlike morphology. These nanoparticles are synthesized in the presence of silver ions by a seed-mediated approach based on utilizing highly purified pentahedrally twinned gold nanorods and nanowires as seed particles. The extent of the growth can be varied, leading to shifts in the plasmon resonances of the particles. In addition, the application of the starfruit rods for surface-enhanced Raman spectroscopy (SERS) is demonstrated. © 2012 American Chemical Society.


Wei J.,Rice University | Ji H.,Rice University | Guo W.,Rice University | Nevidomskyy A.H.,Rice University | Natelson D.,Rice University
Nature Nanotechnology | Year: 2012

Vanadium dioxide is a strongly correlated material that undergoes a metalĝinsulator transition from a high-temperature, rutile metal to a monoclinic insulating state at 67 °C. In recent years, experiments on single-crystal vanadium-dioxide nanowires grown by physical vapour deposition have shed light on the crucial role of strain in the structural and electronic phase diagram of this material, including evidence for a new M2 phase, but the detailed physics of this material is still not fully understood. The transition temperature can be reduced by doping with tungsten, but this process is not reversible. Here, we show that the metalĝinsulator transition in nanoscale beams of vanadium dioxide can be strongly modified by doping with atomic hydrogen using the catalytic spillover method. We also show that this process is completely reversible, and that the metalĝinsulator transition eventually vanishes when the doping exceeds a threshold value. Raman and conventional optical microscopy, electron diffraction and transmission electron microscopy provide evidence that the structure of the metallic post-hydrogenation state is similar to that of the rutile state. First-principles electronic structure calculations confirm that a distorted rutile structure is energetically favoured following hydrogenation, and also that such doping favours metallicity from both the Mott and Peierls perspectives. We anticipate that hydrogen doping will be a powerful tool for examining the metalĝinsulator transition and for engineering the properties of vanadium dioxide.© 2012 Macmillan Publishers Limited.


Gopal A.,University of Maryland University College | Koka B.R.,Rice University
MIS Quarterly: Management Information Systems | Year: 2012

In this paper, the interacting effect of formal contracts and relational governance on vendor profitability and quality in the software outsourcing industry are examined. We focus on a critical manifestation of relational governance-The presence of relational flexibility in the exchange relationship-and argue that the enacted observation of relational flexibility is driven by perceptions of exchange hazards. In a departure from extant literature, however, we propose that the benefits accruing from it are asymmetric and depend on how the exchange risks are apportioned by the formal contract. Formally, we hypothesize that relational flexibility provides greater benefits to an exchange partner that faces the greater proportion of risk in a project, induced through the contract. In addition, we hypothesize that these benefits manifest on the performance dimensions that are of importance to the risk-exposed partner. We test our hypotheses on 105 software projects completed by a software outsourcing vendor for multiple clients. The results show that relational flexibility positively affects profitability in only fixed price contracts, where the vendor faces greater risk, while positively affecting quality only in time and materials contracts, where the client is at greater risk. We thus provide evidence for the asymmetric benefits from relational governance, thereby arguing for a more contingent and limited view of the value of relational governance, based on risk-exposure, rather than the more expansive view prevalent in the literature contending that relational governance provides benefits for all parties to an exchange. We conclude with a discussion of the research and managerial implications of our findings.


Zou X.,Rice University | Yakobson B.I.,Rice University
Accounts of Chemical Research | Year: 2015

CONSPECTUS: While some exceptional properties are unique to graphene only (its signature Dirac-cone gapless dispersion, carrier mobility, record strength), other features are common to other two-dimensional materials. The broader family "beyond graphene" offers greater choices to be explored and tailored for various applications. Transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), and 2D layers of pure elements, like phosphorus or boron, can complement or even surpass graphene in many ways and uses, ranging from electronics and optoelectronics to catalysis and energy storage. Their availability greatly relies on chemical vapor deposition growth of large samples, which are highly polycrystalline and include interfaces such as edges, heterostructures, and grain boundaries, as well as dislocations and point defects. These imperfections do not always degrade the material properties, but they often bring new physics and even useful functionality. It turns particularly interesting in combination with the sheer openness of all 2D sheets, fully exposed to the environment, which, as we show herein, can change and tune the defect structures and consequently all their qualities, from electronic levels, conductivity, magnetism, and optics to structural mobility of dislocations and catalytic activities. In this Account, we review our progress in understanding of various defects. We begin by expressing the energy of an arbitrary graphene edge analytically, so that the environment is regarded by "chemical phase shift". This has profound implications for graphene and carbon nanotube growth. Generalization of this equation to heteroelemental BN gives a method to determine the energy for arbitrary edges of BN, depending on the partial chemical potentials. This facilitates the tuning of the morphology and electronic and magnetic properties of pure BN or hybrid BN|C systems. Applying a similar method to three-atomic-layer TMDCs reveals more diverse edge structures for thermodynamically stable flakes. Moreover, CVD samples show new types of edge reconstruction, providing insight into the nonequilibrium growth process. Combining dislocation theory with first-principles computations, we could predict the dislocation cores for BN and TMDC and reveal their variable chemical makeup. This lays the foundation for the unique sensitivity to ambient conditions. For example, partial occupation of the defect states for dislocations in TMDCs renders them intrinsically magnetic. The exchange coupling between electrons from neighboring dislocations in grain boundaries further makes them half-metallic, which may find its applications in spintronics. Finally, brief discussion of monoelemental 2D-layer phosphorus and especially the structures and growth routes of 2D boron shows how theoretical assessment can help the quest for new synthetic routes. (Figure Presented). © 2014 American Chemical Society.


Foster M.S.,Rice University | Yuzbashyan E.A.,Rutgers University
Physical Review Letters | Year: 2012

We show that arbitrarily weak interparticle interactions destabilize the surface states of 3D topological superconductors with spin SU(2) invariance (symmetry class CI) in the presence of nonmagnetic disorder. The conduit for the instability is disorder-induced wave function multifractality. We argue that time-reversal symmetry breaks spontaneously at the surface, so that topologically protected states do not exist for this class. The interaction-stabilized surface phase is expected to exhibit ferromagnetic order, or to reside in an insulating plateau of the spin quantum Hall effect. © 2012 American Physical Society.


Willingham B.,Rice University | Link S.,Rice University
Optics Express | Year: 2011

We investigate the propagation of surface plasmon polaritons through coupling of light to sub-radiant dipole modes in finite chains of Ag nanoparticles. End excitation of collections of closely spaced particles reveals a band of sub-radiant modes whereby the decay of surface plasmon polaritons due to radiative losses is minimized. We show that excitation of any of these sub-radiant modes results in the most efficient energy transfer throughout the optical spectrum, with smaller interparticle separations resulting in the longest propagation. © 2011 Optical Society of America.


Mayer K.M.,Rice University
Nanotechnology | Year: 2010

Noble metal nanoparticles exhibit sharp spectral extinction peaks at visible and near-infrared frequencies due to the resonant excitation of their free electrons, termed localized surface plasmon resonance (LSPR). Since the resonant frequency is dependent on the refractive index of the nanoparticle surroundings, LSPR can be the basis for sensing molecular interactions near the nanoparticle surface. However, previous studies have not yet determined whether the LSPR mechanism can reach the ultimate sensing limit: the detection of individual molecules. Here we demonstrate single molecule LSPR detection by monitoring antibody-antigen unbinding events through the scattering spectra of individual gold bipyramids. Both experiments and finite element simulations indicate that the unbinding of single antigen molecules results in small, discrete < 0.5 nm blue-shifts of the plasmon resonance. The unbinding rate is consistent with antibody-antigen binding kinetics determined from previous ensemble experiments. According to these results, the effective refractive index of a single protein is approximately 1.54. LSPR sensing could therefore be a powerful addition to the current toolbox of single molecule detection methods since it probes interactions on long timescales and under relatively natural conditions.


Zhu H.,Rice University
Nanotechnology | Year: 2010

Methods for synthesizing quantum dots generally rely on very high temperatures to both nucleate and grow core and core-shell semiconductor nanocrystals. In this work, we generate highly monodisperse ZnS and CdZnS shells on CdSe semiconductor nanocrystals at temperatures as low as 65 degrees C by enhancing the precursor solubility. Relatively small amounts of trioctylphosphine and trioctylphosphine oxide have marked effects on the solubility of the metal salts used to form shells; their inclusion in the precursor solutions, which use thiourea as a sulfur source, can lead to homogeneous and fully dissolved solutions. Upon addition to suspensions of quantum dot cores, these precursors deposit as uniform shells; the lowest temperature for shell growth (65 degrees C) yields the thinnest shells (d < 1 nm) while the same process at higher temperatures (180 degrees C) forms thicker shells (d approximately 1-2 nm). The growth of the shell structures, average particle size, size distribution, and shape were examined using optical spectroscopy, transmission electron microscopy, x-ray diffraction, and transmittance small angle x-ray scattering. The photoluminescence quantum yield (QY) of the as-prepared CdSe/ZnS quantum dots ranged from 26% to 46% as compared to 10% for the CdSe cores. This method was further generalized to CdZnS shells by mixing cadmium and zinc acetate precursors. The CdSe/CdZnS nanocrystals have a thicker shell and higher QY (40% versus 36%) as compared to the CdSe/ZnS prepared under similar conditions. These low temperature methods for shell growth are readily amenable to scale-up and can provide a route for economical and less energy intensive production of quantum dots.


Trigeminal sensory innervation of the cornea is critical for protection and synthesis of neuropeptides required for normal vision. Little is known about axon guidance during mammalian corneal innervation. In contrast to the chick where a pericorneal nerve ring forms via Npn/Sema signaling, mouse corneal axons project directly into the presumptive cornea without initial formation of an analogous nerve ring. Here we show that during development of the mouse cornea, Npn1 is strongly expressed by the trigeminal ganglion whereas Npn2 is expressed at low levels. At the same time Sema3A and Sema3F are expressed in distinct patterns in the ocular tissues. Npn1(sema-/-) mutant corneas become precociously and aberrantly innervated by nerve bundles that project further into the corneal stroma. In contrast, stromal innervation was not affected in Npn2(-/-) mutants. The corneal epithelium was prematurely innervated in both Npn1(sema-/-) and Npn2(-/-) mutants. These defects were exacerbated in Npn1(sema-/-);Npn2(-/-) double mutants, which in addition showed ectopic innervation of the region between the optic cup and lens vesicle. Collectively, our data show that Sema3A/Npn1 and Sema3F/Npn2 signaling play distinct roles and both are required for proper innervation of the mouse cornea.


Nicolaou K.C.,Rice University
Journal of the American Chemical Society | Year: 2016

The total synthesis of the spliceosome inhibitor thailanstatin A has been achieved in a longest linear sequence of nine steps from readily available starting materials. A key feature of the developed synthetic strategy is the implementation of a unique, biomimetic asymmetric intramolecular oxa-Michael reaction/hydrogenation sequence that allows diastereodivergent access to highly functionalized tetrahydropyrans, which can be used for the synthesis of designed analogues of this bioactive molecule. © 2016 American Chemical Society.


Ruan G.,Rice University | Sun Z.,Rice University | Peng Z.,Rice University | Tour J.M.,Rice University
ACS Nano | Year: 2011

In its monolayer form, graphene is a one-atom-thick two-dimensional material with excellent electrical, mechanical, and thermal properties. Large-scale production of high-quality graphene is attracting an increasing amount of attention. Chemical vapor and solid deposition methods have been developed to grow graphene from organic gases or solid carbon sources. Most of the carbon sources used were purified chemicals that could be expensive for mass production. In this work, we have developed a less expensive approach using six easily obtained, low or negatively valued raw carbon-containing materials used without prepurification (cookies, chocolate, grass, plastics, roaches, and dog feces) to grow graphene directly on the backside of a Cu foil at 1050 °C under H2/Ar flow. The nonvolatile pyrolyzed species were easily removed by etching away the frontside of the Cu. Analysis by Raman spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy indicates that the monolayer graphene derived from these carbon sources is of high quality. © 2011 American Chemical Society.


Yakobson B.I.,Rice University | Ding F.,Hong Kong Polytechnic University
ACS Nano | Year: 2011

As the available length ranges expand, graphene begins to show its anticipated polycrystallinity. Its texture, revealed with modern comprehensive microscopy in recent work by Kim et al., includes coherent domains/grains oriented randomly yet with an intriguing degree of regularity. The domains are stitched together by pentagons and heptagons aligned into the grain boundaries. The challenge is now to deduce the mechanisms of formation based on observations and then to find ways to control the morphology toward useful properties and applications. © 2011 American Chemical Society.


He X.,Rice University
Nature Nanotechnology | Year: 2016

The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios. © 2016 Nature Publishing Group


Hernandez-Fajardo I.,Rice University | Duenas-Osorio L.,Rice University
Earthquake Spectra | Year: 2011

Realistic models of service networks must consider the evolution of interactions with external systems to evaluate emergent response effects on individual network performance. This paper introduces a new dynamic methodology for the assessment of systemic fragility propagation across interdependent networks subjected to seismic action that improves existing static methodologies. Interdependencies are discrete, unidirectional relationships between elements of distinct networks, which are able to influence response evolution from transient to steadystate stages. Comparisons of systemic fragility curves results for isolated and interdependent power and water networks display the importance of interdependence strength and density properties. For the test water network, inter-systemic failure propagation increases its connectivity loss by up to 24%, while high interdependence strengths make the median fragility rise up to 56.2%. In contrast, reductions of interdependence density improve the median water fragility up to 81.7%. Insights obtained from this model, and its associated sequential fragility algorithm, reveal complex coupling patterns and interdependence-based mitigation strategies that are essential for lifeline system management. © 2011, Earthquake Engineering Research Institute.


Nakhleh L.,Rice University
Trends in Ecology and Evolution | Year: 2013

An intricate relation exists between gene trees and species phylogenies, due to evolutionary processes that act on the genes within and across the branches of the species phylogeny. From an analytical perspective, gene trees serve as character states for inferring accurate species phylogenies, and species phylogenies serve as a backdrop against which gene trees are contrasted for elucidating evolutionary processes and parameters. In a 1997 paper, Maddison discussed this relation, reviewed the signatures left by three major evolutionary processes on the gene trees, and surveyed parsimony and likelihood criteria for utilizing these signatures to elucidate computationally this relation. Here, I review progress that has been made in developing computational methods for analyses under these two criteria, and survey remaining challenges. © 2013 Elsevier Ltd.


Jin Z.,Rice University | Yao J.,Rice University | Kittrell C.,Rice University | Tour J.M.,Rice University
ACS Nano | Year: 2011

In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. Doping with electron-donor nitrogen heteroatoms can modulate the electronic properties of graphene to produce an n-type semiconductor. Here we demonstrate the growth of monolayer nitrogen-doped graphene in centimeter-scale sheets using a chemical vapor deposition process with pyridine as the sole source of both carbon and nitrogen. High-resolution transmission microscopy and Raman mapping characterizations indicate that the nitrogen-doped graphene sheets are uniformly monolayered. The existence of nitrogen-atom substitution in the graphene planes was confirmed by X-ray photoelectron spectroscopy. Electrical measurements show that the nitrogendoped graphene exhibits an n-type behavior, different from pristine graphene. The preparation of large-area nitrogen-doped graphene provides a viable route to modify the properties of monolayer graphene and promote its applications in electronic devices. © 2011 American Chemical Society.

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