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Credit: The National University of Science and Technology MISIS Materials scientists from NUST MISIS, together with colleagues from the Department of Chemistry at Lomonosov Moscow State University, have developed a cheap and qualitative method of delivering blood samples and other biological fluids over any distance to be analyzed in laboratories. The developed method is similar to the technology of obtaining dry blood spots, which has already proven useful in neonatal screening. The new technology in this field has wide-ranging possibilities, and in the near future, may displace traditional methods of sample collection to become the new method of screening populations for communicable diseases (HIV, hepatitis, tuberculosis, etc.). These possibilities are now being discussed in professional environments. "[The method] used for neonatal screening and obtaining dry blood samples involves a few blood drops are applied to special cellulose carriers and then dried in air. It requires special cards not produced in Russia, as well as expensive specialized equipment for obtaining samples of biomaterial for further analysis. And this technology doesn't even exist in every major city. Additionally, the difficulty of using such carriers for quantitative analysis of animal and human blood is caused by irregularity of its diffusion on carriers due to the complex structure of cellulose and the presence of inconvertible adsorption of blood components, which greatly distorts the results of analysis," said Associate Professor Alexander Osipov, one of developers of the project. That is why at the present time, medial syringes for gathering liquid samples of blood or serum for delivery to laboratories in special containers with specific temperature conditions (often frozen) are used in medical and veterinary diagnosis. The whole process is quite expensive and inconvenient. In addition, if a violation of temperature or time conditions occurs during the delivery or storage, blood samples lose their properties, possibly leading to incorrect results. This problem was solved by replacing the cellulose with specially prepared porous inorganic material containing nanoparticles of metals. Scientists chose the composition and form of the absorbent to ensure the blood was evenly distributed throughout the volume, and upon washing the analyzed blood components, it almost completely passed into solution. Modified samples dry about two times faster, which critically speeds up the sample preparation process. To transport to a laboratory, the card is put in an envelope and sent by mail without need of special transport, which leads to significant financial savings. For example, in past events of an emergency epidemiological situation – like the outbreak of the Siberian plague in Yamal in 2016 – the cost of express delivery of a batch of biomaterials to a Moscow lab amounted to several million rubles. The cost of the card itself in manual, small-scale wholesale production is five times lower than industrial imported cellulose—40 rubles vs. 180 rubles. When considering large-scale production, the price will be even lower. Now, the creators of the new sample preparation technology have focused on veterinary diagnosis, because in animal breeding and farming, there is a need to conduct hundreds of thousands of tests, but there are no conditions for these tests on farms located in remote areas. Now, scientists are collaborating with some of Russia`s largest poultry and animal farms, which determines the level of bird immunity, vaccinations, the presence of the FMD virus, rabies, leukemia, and other particularly dangerous infections animals may have. After the completion of testing and certification procedures, it will be possible to start the serial production of a pilot series of membrane carriers of the new model for sample selection. According to preliminary estimates, all necessary documents will be ready by the end of 2017. The researchers are approaching Russian diagnostic laboratories for use of the new technology in medical diagnostics, including screenings for communicable diseases such as hepatitis, HIV, and others. In addition, several large companies from Southeast Asia have also expressed interest in using the new system both in veterinary and medical diagnostics. Explore further: Novel device that enables blood collection anytime and anywhere listed with the FDA


News Article | February 15, 2017
Site: phys.org

Ellipsoid plot of (N5)6(H3O)3(NH4)4Cl at the 50% probability level. The occupancies of H3O+ (O1), H3O+ (O2), Clˉ, N5ˉ, and NH4+ are 1/12, 1/24, 1/24, 1/4, and 1/6, respectively. Credit: (c) Science (2017). DOI: 10.1126/science.aah3840 (Phys.org)—The pentazole molecule and its anion, cyclo-N - has proven elusive to researchers for almost a century. The pentazole anion is highly unstable and cannot be made in bulk. Researchers from Nanjing University of Science and Technology and the University of Science and Technology Liaoning have devised a synthesis of a salt containing the pentazole anion that is stable up to 117oC. Their report appears in Science. The pentazole and its anion have a sordid history, at least for molecules. Pentazole was thought to be isolated as an arylpentazole in 1915, but was disproven several years later. Then, in the 1950s, a group of researchers managed to identify pentazole as an intermediate for another reaction. Later researchers became interested in combining N + and N - as a possible alternative to hydrazine as rocket fuel. Many attempts have been made to isolate the pentazole anion by cleaving the carbon-nitrogen bond in an arylpentazole. However, these have proven unsuccessful because of the difficulties in selectively cleaving the carbon-nitrogen bond. The addition of electron donating groups at the ortho and para positions of the arene helped with selective cleavage. In the current study, Zhang et al. were able to selectively cleave the carbon-nitrogen bond of 3,5-dimethyl-4-hydroxyphenylpentazole and stabilize the resulting pentazole anion using ferrous bisglycinate, Fe(Gly) . The anion was isolated as part of a salt, (N ) (H O) (NH ) Cl (19% yield). The Fe(Gly) stabilizer also served as a mediator for m-chloroperbenzoic acid. The molecular conformation of the salt ions was determined using single-crystal x-ray diffraction analysis where the five nitrogen atoms in cylco-N - are co-planar and aromatic. The structure was confirmed using 1H and 15N NMR as well as infrared and Raman spectroscopy. Additional studies showed that the salt is remarkably thermally stable up to 117oC, which is attributed to the salt's hydrogen bonding arrangement. All of the ions in the salt apparently play a role in stabilizing the pentazole anion. When Zhang et al. removed Cl- or when they removed NH +, cyclo-N - decomposed. This research allows for the isolation and characterization of an elusive aromatic azole molecule, one that has been out of reach for chemists for many years, and according to the authors this ends the search for this elusive molecule. More information: Chong Zhang et al. Synthesis and characterization of the pentazolate anion-Nˉ in (N)(HO)(NH)Cl, Science (2017). DOI: 10.1126/science.aah3840 Abstract Pentazole (HN5), an unstable molecular ring comprising five nitrogen atoms, has been of great interest to researchers for the better part of a century. We report the synthesis and characterization of the pentazolate anion stabilized in a (N5)6(H3O)3(NH4)4Cl salt. The anion was generated by direct cleavage of the C–N bond in a multisubstituted arylpentazole using m-chloroperbenzoic acid and ferrous bisglycinate. The structure was confirmed by single-crystal x-ray diffraction analysis, which highlighted stabilization of the cyclo-N5ˉ ring by chloride, ammonium, and hydronium. Thermal analysis indicated the stability of the salt below 117°C on the basis of thermogravimetry-measured onset decomposition temperature.


News Article | November 18, 2016
Site: www.eurekalert.org

A major step forward in establishing an unprecedented regional regime to develop microsatellite technologies and share and use collected data. The memorandum of understanding to create the Asian Micro-satellite Consortium (AMC) will come into effect on November 18, marking a major step forward in establishing an unprecedented regional regime to develop microsatellite technologies and share and use collected data relating to the environment and natural disasters, etc. The consortium will comprise 16 space agencies and universities from nine Asian nations, including Japan. Microsatellites have rapidly become a major factor in space exploitation, and their advent could spur a revolution comparable to that which followed the launch of humankind's first satellite, Sputnik-1, in 1957. The advantages of microsatellites are multifold: In general, they can be developed within a few years, which is much faster than the 10 years required for some larger satellites; they generally weigh 100 kilograms or less; and they are cheaper to build, costing about one-hundredth the price of large satellites. It is essential for Japan and other Asian nations to create an effective international framework toward the goal of obtaining state-of-the-art satellite bus and sensing technologies and the sharing and use of satellite-collected data, thereby maintaining a global presence in the field--this is the notion that has driven the formation of the AMC. The 16 participating institutions are space agencies, governmental institutes or top-class universities from Bangladesh, Indonesia, Japan, Malaysia, Mongolia, Myanmar, Philippines, Thailand and Vietnam (see list below). Data relating to such fields as natural disasters and the environment are of great value to these disaster-prone nations. They also help tackle the issue of environmental destruction. The AMC is also expected to make it much easier to share and standardize satellite bus and sensing technologies, observational data, and data application methodologies. In the future, the consortium is expected to share and utilize data collected by about 50 microsatellites that the participating nations are planning to launch. These microsatellites will allow the AMC to monitor any given location on the Earth around the clock, therefore making it possible to grasp a variety of situations, including major disasters if one should occur. The standardization of advanced optical sensors and other devices is essential in order to effectively make use of satellite-gathered data. By using drones mounted with such sensors for ground observation in international joint undertakings, it will drastically increase the volume of data gathered and the precision of ground verification. Data verified on the ground would also help researchers make far more accurate satellite-data-based estimates. The resultant effects could be enormous in such areas as disaster preparedness/mitigation, global environment change, promotion of agriculture, forestry, fisheries and mining, and countermeasures against air and marine pollution. The signing ceremony for the consortium will be held on November 18th at Hotel Jen in Manila, Philippines. Yukihiro Takahashi, the professor at Hokkaido University who led the formation of the AMC says "I believe that the consortium will trigger the advanced space utilization with microsatellites not only in Asia but also all over the world including Africa and South America". Indonesian National Institute of Aeronautics and Space (LAPAN) Agency for the Assessment and Application of Technology (BPPT) National University of Mongolia (NUM) New Mongol Institute of Technology (NMIT) German-Mongolian Institute for Resources and Technology (GMIT) Philippine Council for Industry, Energy and Emerging Technology Research and Development (DOST-PCIEERD) Vietnam National Satellite Center (VAST-VNSC) University of Science and Technology of Hanoi (VAST-USTH)


Cesium lead bromide perovskite nanocrystals are used to generate white light that can be used as both an efficient lighting source and for ultrafast data transfer. The growing demands for high-speed data communications (e.g., for the Internet) have greatly exceeded all predictions, and have thus greatly accelerated research and development activities for next-generation wireless communication systems.1, 2 As part of these efforts, visible light communication (VLC)—in which electromagnetic radiation at visible wavelengths (380–700nm) is used, rather than conventional radio frequency (RF) waves—has recently been proposed as a promising technology for enabling simultaneous energy-efficient illumination and high-speed data communication. Indeed, VLC has several advantages over conventional RF-based communication systems, including high security, fast speed, as well as an unregulated and uncrowded bandwidth. In a typical VLC system, LEDs or laser diodes (LDs) with phosphors (i.e., blue, green, and yellow/red color converters) are used in the transmitters to generate white light for solid-state light (SSL) and data communications.3, 4 There is, however, a phosphor-associated limitation in the modulation bandwidth of the VLC system. That is, the long excited-state lifetime (the time it takes to re-emit an absorbed photon) of conventional yttrium-aluminum-garnet (YAG)-based phosphors gives rise to a serious bottleneck in VLC applications.5 This phosphor-associated bandwidth thus limits VLC systems to about 10MHz and nullifies its key advantages over RF communication systems.4, 6 To overcome the drawback associated with conventional YAG phosphors, several alternative materials have been tested as color converters for VLC systems, including boron-dipyrromethene, poly[2-methoxy-5-(2'-ethylhexyloxy)-p-pheny-lene vinylene, and poly[2,5-bis(2',5'-bis(2”-ethylhexyloxy)phenyl)-p-phenylene vinylene (more commonly known as BODIPY, MEH-PPV, and BBEHP-PPV, respectively).7, 8 These other candidates, however, also suffer from relatively long excited-state lifetimes that also greatly limit their modulation bandwidth frequency and speed of data transmission. Developing an ideal color-converter phosphor material, with a short excited-state lifetime (i.e., fast light-intensity decay) and high efficiency (high brightness), therefore remains the major challenge for VLC and SSL applications. In recent years, perovskites have emerged as ‘magic’ materials for optoelectronic applications (e.g., photovoltaics and photodetectors). Moreover, recent studies have revealed that perovskite nanocrystals (NCs)—in the form of cesium lead bromide (CsPbBr )—have relatively high photoluminescence quantum yields (PLQYs) and short photoluminescence (PL) lifetimes.6, 9 In fact, this marriage of high PLQY and short PL lifetime is the essential requirement for ideal SSL and VLC color converters. In our work,6 we have therefore investigated the fast color-conversion behavior of CsPbBr perovskite NCs when they are used as a phosphor for white light transmission in an SSL-VLC dual-function system. Our perovskite NCs are inexpensive and relatively easy to prepare (i.e., in a toluene solution). In our study, we synthesized CsPbBr perovskite NCs that have a cubic shape and average dimensions of about 80nm (see Figure 1). We have also used time-resolved laser spectroscopy to study the excited-state dynamics of our NCs because this is the key characteristic for fast-response color-conversion materials. We measured a relatively short PL lifetime of about 7ns, which indicates that our materials outperform conventional phosphors (with PL lifetimes on the order of microseconds). Figure 1. Illustrations of the cesium lead bromide (CsPbBr ) perovskite nanocrystals (NCs). (a) High-resolution transmission microscopy image of the NCs. Photographic images of the NCs in a toluene solution are also shown, under (b) ambient light and (c) UV illumination. As part of our work we mixed our synthesized green-emitting perovksite NCs with a conventional red phosphor to attain white light. We excited the mixture with the use of an indium-gallium-nitride-based blue LD, and thus produced a warm white light. The corresponding chromaticity coordinates (0.38, 0.30) of this light are presented—within the International Commission on Illumination (CIE) 1931 color space—in Figure 2. We find that the converted light exhibits a correlated color temperature of 3236K, which mimics warm sunlight. The converted light also has a high color-rendering index of 89, which is better than white light produced from a yellow YAG phosphor alone. When the blue light excites an electron within the NCs, an electron-hole pair (known as an exciton) is formed. The small size of our NCs, however, means that the exciton energy levels are changed. This makes the electron more likely to recombine with its hole and emit a photon (in the green color regime). This result indicates that our high-quality perovskite NCs are a cost-effective color-converter option for laser-based indoor illumination. In addition, by varying the chemical composition of our perovskite NCs (e.g., by substituting different halides or metal ions), we can achieve flexible fine tuning of the color. Figure 2. White light generated from the CsPbBr perovskite NCs has chromacity (x, y) coordinates of 0.38, 0.30 in the International Commission of Illumination (CIE) 1931 color space, as well as a color-rendering index (CRI) of 89 and a correlated color temperature (CCT) of 3236K. Inset: Photograph of the white light generated from a mixture of green-emitting perovskite NC phosphor and a red-emitting nitride phosphor (collectively excited by blue laser light). We have also performed a small-signal frequency-response measurement to assess the modulation bandwidth of the white light that is generated from our CsPbBr -NC-based color converter. Although the conventional red-emitting phosphor that we use in the system only provides a limited bandwidth of about 12MHz, our additional use of the perovskites produces a greatly increased bandwidth of about 491MHz. Our new color converters can thus provide a bandwidth that is 40 times that of commercial phosphors. This is especially important in the current bandwidth-hungry era, when there is a continuous push for VLC systems that have ever-higher bit rates. In addition, high-speed LDs will eventually replace LEDs for the generation of white light in VLC systems. Our work therefore represents progress toward the development of NCs that convert high-energy photons from violet-blue LDs to red-yellow-green lights with ultrashort photon lifetimes. In the last part of our study, we demonstrated that our novel VLC system has a data transmission rate of 2Gb/s when we use a non-return-to-zero on-off keying modulation scheme. We also tested the corresponding bit error rate (BER) at the same time, to verify that an error-free communication link could be established. At data rates of 1, 1.5, and 2Gb/s, we thus obtained a BER of 1.2 × 10−7, 3.4 × 10−7, and 7.4 × 10−5, respectively, all of which easily pass the forward error-correction limit (with BER ≤ 3.8 × 10−3). In summary, we have synthesized CsPbBr perovskite NCs and have studied their use as a phosphor for white-light transmission. Our results indicate that these NCs have short photoluminescence lifetimes. In addition, the converted white light has a correlated color temperature similar to that of warm sunlight and a high color-rendering index. Moreover, our color converters have modulation bandwidths that are 40 times greater than those of conventional phosphors and we have demonstrated ultrafast data transfer rates. Our NC-based color converters thus present a new platform for next-generation SSL-VLC systems that offer simultaneous high-brightness lighting and Gb/s data transfer rates. In the near term, we plan to further improve the light-conversion yield of our nanocrystals, i.e., to produce near-ideal white light with a color-rendering index close to 100, while also being able to transmit data at bit rates of multi-gigabits per second. This work is supported by the King Abdullah University of Science and Technology and the King Abdulaziz City for Science and Technology (grant KACST TIC R2-FP-008). Division of Physical Sciences and Engineering King Abdullah University of Science and Technology (KAUST) Ibrahim Dursun is currently pursuing his PhD. He is working on a solution-processable hybrid perovskite for light-emissive applications. He previously obtained a master's in optics and photonics from Aix-Marseille University (France) and the Karlsruhe Institute of Technology (Germany) in 2013. He completed his undergraduate studies in physics at Izmir Institute of Technology (Turkey) in 2011. Osman Bakr is an associate professor of materials science and engineering. He has a BSc in materials science and engineering from the Massachusetts Institute of Technology (2003), as well as an MS and a PhD in applied physics from Harvard University (2009). His research group focuses on the study of hybrid organic–inorganic materials, particularly by advancing their synthesis and self-assembly for applications in photovoltaics and optoelectronics. Chao Shen and Boon S. Ooi Computer, Electrical, and Mathematical Sciences and Engineering KAUST Thuwal, Saudi Arabia Chao Shen received his BSc in materials physics from Fudan University, China, in 2011, and is currently a PhD candidate. His research interests include III-nitride laser diodes, superluminescent diodes, and micro-LEDs, as well as their applications for solid-state lighting, visible light communications, and photonic integrated circuits. Boon Ooi is a professor of electrical engineering. His research is focused on the development of gallium-nitride-based LEDs and lasers, as well as visible light communications. He is a fellow of SPIE. Division of Physical Sciences and EngineeringKing Abdullah University of Science and Technology (KAUST) 1. Y.-C. Chi, D.-H. Hsieh, C.-Y. Lin, H.-Y. Chen, C.-Y. Huang, J.-H. He, B. Ooi, et al., Phosphorus diffuser diverged blue laser diode for indoor lighting and communication, Sci. Rep. 5, p. 18690, 2015. 3. C. Shen, T. K. Ng, J. T. Leonard, A. Pourhashemi, S. Nakamura, S. P. DenBaars, J. S. Speck, A. Y. Alyamani, M. M. El-desouki, B. S. Ooi, High-brightness semipolar (2021) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications, Opt. Lett. 41, p. 2608-2611, 2016. 4. C. Lee, C. Shen, H. M. Oubei, M. Cantore, B. Janjua, T. K. Ng, R. M. Farrell, et al., 2Gbit/s data transmission from an unfiltered laser-based phosphor-converted white lighting communication system, Opt. Express 23, p. 29779-29787, 2015. 6. I. Dursun, C. Shen, M. R. Parida, J. Pan, S. P. Sarmah, D. Priante, N. Alyami, et al., Perovskite nanocrystals as a color converter for visible light communication, ACS Photon. 3, p. 1150-1156, 2016. 7. M. T. Sajjad, P. P. Manousiadis, H. Chun, D. A. Vithanage, S. Rajbhandari, A. L. Kanibolotsky, G. Faulkner, et al., Novel fast color-converter for visible light communications using a blend of conjugated polymers, ACS Photon. 2, p. 194-199, 2015. 8. M. T. Sajjad, P. P. Manousiadis, C. Orofino, D. Cortizo-Lacalle, A. L. Kanibolotsky, S. Rajbhandari, D. Amarasinghe, et al., Fluorescent red-emitting BODIPY oligofluorene star-shaped molecules as a color converter material for visible light communications, Adv. Opt. Mater. 3, p. 536-540, 2015. 9. L. Protesescu, S. Yakunin, M. I. Bodnarchuk, F. Krieg, R. Caputo, C. H. Hendon, R. X. Yang, A. Walsh, M. V. Kovalenko, Nanocrystals of cesium lead halide perovskites (CsPbX , X = Cl, Br, and I): novel optoelectronic materials showing bright emission with wide color gamut, Nano Lett. 15, p. 3692-3696, 2015.


STM image showing isolated single ZnPc molecules adsorbed on either a three-monolayer NaCl island or bare Ag(100) (image size: 34 nm × 25 nm; scanning parameters: −1.7 V, 2 pA). Credit: (c) Nature (2016). DOI: 10.1038/nature17428 (Phys.org)—A team of researchers with the University of Science and Technology in China has for the first time, imaged dipole-dipole interactions using scanning tunneling microscopy. In their paper published in the journal Nature, the team describes how they captured the imagery and why they believe they may have also captured an instance of entanglement of chromophores. Guillaume Schull with Institutde Physique et Chimie des Matériaux de Strasbourg outlines the work done by the team in a News & Views article published in the same journal issue and explains in more detail the importance of better understanding the interactions of dipoles in biological processes. Molecules with atoms that have unequal numbers of electrons are known as dipoles—different sides can be positively or negatively charged causing interactions with other molecules to come about. Interactions between dipoles is a major area of research because it is part of such important processes as photosynthesis. In plants, dipole interactions aide chromophore couplings—helping to transfer energy from sunlight to other molecules that later convert it to energy. How exactly this process works is still not fully understood, unfortunately, and for that reason, researchers have been trying to capture images of it as it occurs—but until now, have been unsuccessful because light based microscopes can only see images to a certain small size. In this new effort, the researchers used scanning tunneling microscopy to get the job done. To capture the images, the researchers used chromophores that were made using a purple dye and then focused a red light on them to further highlight details. Next, they used the tip of the tunneling device to push some of the chromophores together—as they did so, they noticed that at approximately 3 nanometers apart, the light given off by the chromophores began to change; imagery of that change showed the process of dipole-dipole interactions taking place. But, that was not the end of the story, in recent years some scientists have begun to suspect that entanglement occurs during dipole-dipole interactions. As part of their experiments, the researchers varied the numbers of chromophores involved in the coupling, trying clusters up to four in size. In so doing they found that the way that the light changed between them, might be an indication of entanglement. Explore further: Dueling dipoles: In search of a new theory of photosynthetic energy transfer More information: Yang Zhang et al. Visualizing coherent intermolecular dipole–dipole coupling in real space, Nature (2016). DOI: 10.1038/nature17428 Abstract Many important energy-transfer and optical processes, in both biological and artificial systems, depend crucially on excitonic coupling that spans several chromophores. Such coupling can in principle be described in a straightforward manner by considering the coherent intermolecular dipole–dipole interactions involved. However, in practice, it is challenging to directly observe in real space the coherent dipole coupling and the related exciton delocalizations, owing to the diffraction limit in conventional optics. Here we demonstrate that the highly localized excitations that are produced by electrons tunnelling from the tip of a scanning tunnelling microscope, in conjunction with imaging of the resultant luminescence, can be used to map the spatial distribution of the excitonic coupling in well-defined arrangements of a few zinc-phthalocyanine molecules. The luminescence patterns obtained for excitons in a dimer, which are recorded for different energy states and found to resemble σ and π molecular orbitals, reveal the local optical response of the system and the dependence of the local optical response on the relative orientation and phase of the transition dipoles of the individual molecules in the dimer. We generate an in-line arrangement up to four zinc-phthalocyanine molecules, with a larger total transition dipole, and show that this results in enhanced 'single-molecule' superradiance from the oligomer upon site-selective excitation. These findings demonstrate that our experimental approach provides detailed spatial information about coherent dipole–dipole coupling in molecular systems, which should enable a greater understanding and rational engineering of light-harvesting structures and quantum light sources.


News Article | November 22, 2016
Site: physicsworld.com

The first International Conference on Radiations and Applications (following six issues of the former National Conference on Radiations and Applications) will be jointly organized by the Faculty of Physics of Houari Boumediene University of Science and Technology (USTHB), SNIRM and LEQ laboratories and the Algerian Association of Physics (AAP), in Algiers, Algeria, from 20 to 23 November 2017. The conference will have the support of Direction Générale de la Recherche Scientifique et du Développement Technologique (DGRSDT). The main goals of the conference are to allow exchange between scientists working on various aspects of radiation physics, enhance collaboration between physicists and promote partnerships between universities and research centers.


News Article | November 14, 2016
Site: www.sciencedaily.com

Microscopic crystals could soon be zipping drugs around your body, taking them to diseased organs. In the past, this was thought to be impossible -- the crystals, which have special magnetic properties, were so small that scientists could not control their movement. But now a team of Chinese researchers has found the solution, and their discovery has opened new applications that could use these crystals to improve -- and perhaps even save -- many lives. Kezheng Chen and Ji Ma from Quingdou University of Science and Technology, Quingdou, China have published a method of producing superparamagnetic crystals that are much larger than any that have been made before. They recently published their findings in Physics Letters A. If some magnetic materials, such as iron oxides, are small enough -- perhaps a few millionths of a millimeter across, smaller than most viruses -- they have an unusual property: their magnetization randomly flips as the temperature changes. By applying a magnetic field to these crystals, scientists can make them almost as strongly magnetic as ordinary fridge magnets. It might seem odd, but this is the strongest type of magnetism known. This phenomenon is called superparamagnetism. In theory, superparamagnetic particles could be ideal for drug delivery, as they can be directed to a tumor simply by using a magnetic field. Their tiny size, however, has made them difficult to guide precisely -- until now. "The largest superparamagnetic materials that we have been able to make before now were clusters of nanocrystals that were together about a thousand times smaller than these," commented Dr. Chen. "These larger crystals are easier to control using external magnetic fields, and they will not aggregate when those fields are removed, which will make them much more useful in practical applications, including drug delivery." Chen and Ma explained that the high temperature and pressure under which the crystals form made tiny meteorite-like 'micro-particles' of magnetite escape from their surface. This caused the unusual pock-marked appearance of the crystal surfaces and induced a high degree of stress and strain into the lattice of the growing crystals. Crystals that grow under such high stresses and strains form with irregularities and defects in their crystal lattice, and it is these irregularities that are responsible for the unusual magnetic properties of Chen's crystals.. Magnetite crystals of a similar size that are grown at a lower temperature and under normal pressure are only very weakly magnetic. This method of making larger superparamagnetic crystals paves the way for the development of superparamagnetic bulk materials that can be reliably controlled by moderate external magnetic forces, revolutionizing drug delivery to tumors and other sites in the body that need to be targeted precisely. And this is just the beginning. Chen's crystals might, for example, be useful in the many engineering projects that need "smart fluids" that change their properties when a magnetic field is applied. These can already be used to make vehicle suspension systems that automatically adjust as road conditions change, increasing comfort and safety, and to build more comfortable and realistic prosthetic limbs. Now that superparamagnetism is no longer restricted to minute particles that are difficult to handle, researchers can start exploring in which ways this can contribute to improving our lives.


News Article | November 14, 2016
Site: www.rdmag.com

Microscopic crystals could soon be zipping drugs around your body, taking them to diseased organs. In the past, this was thought to be impossible - the crystals, which have special magnetic properties, were so small that scientists could not control their movement. But now a team of Chinese researchers has found the solution, and their discovery has opened new applications that could use these crystals to improve - and perhaps even save - many lives. Kezheng Chen and Ji Ma from Quingdou University of Science and Technology, Quingdou, China have published a method of producing superparamagnetic crystals that are much larger than any that have been made before. They recently published their findings in Physics Letters A. If some magnetic materials, such as iron oxides, are small enough - perhaps a few millionths of a millimeter across, smaller than most viruses - they have an unusual property: their magnetization randomly flips as the temperature changes. By applying a magnetic field to these crystals, scientists can make them almost as strongly magnetic as ordinary fridge magnets. It might seem odd, but this is the strongest type of magnetism known. This phenomenon is called superparamagnetism. In theory, superparamagnetic particles could be ideal for drug delivery, as they can be directed to a tumor simply by using a magnetic field. Their tiny size, however, has made them difficult to guide precisely - until now. "The largest superparamagnetic materials that we have been able to make before now were clusters of nanocrystals that were together about a thousand times smaller than these," commented Dr. Chen. "These larger crystals are easier to control using external magnetic fields, and they will not aggregate when those fields are removed, which will make them much more useful in practical applications, including drug delivery." Chen and Ma explained that the high temperature and pressure under which the crystals form made tiny meteorite-like 'micro-particles' of magnetite escape from their surface. This caused the unusual pock-marked appearance of the crystal surfaces and induced a high degree of stress and strain into the lattice of the growing crystals. Crystals that grow under such high stresses and strains form with irregularities and defects in their crystal lattice, and it is these irregularities that are responsible for the unusual magnetic properties of Chen's crystals. Magnetite crystals of a similar size that are grown at a lower temperature and under normal pressure are only very weakly magnetic. This method of making larger superparamagnetic crystals paves the way for the development of superparamagnetic bulk materials that can be reliably controlled by moderate external magnetic forces, revolutionizing drug delivery to tumors and other sites in the body that need to be targeted precisely. And this is just the beginning. Chen's crystals might, for example, be useful in the many engineering projects that need "smart fluids" that change their properties when a magnetic field is applied. These can already be used to make vehicle suspension systems that automatically adjust as road conditions change, increasing comfort and safety, and to build more comfortable and realistic prosthetic limbs. Now that superparamagnetism is no longer restricted to minute particles that are difficult to handle, researchers can start exploring in which ways this can contribute to improving our lives.


News Article | November 14, 2016
Site: phys.org

Electron micrographs of tiny superparamagnetic crystals of magnetite at different resolutions. The lowest resolution image (a) shows the octahedral crystals. At higher resolution, the 'craters' on the crystal surfaces are clearly visible. The highest resolution image (c) shows some of the defects in the crystal lattice, highlighted with the white arrows. Credit: Elsevier B.V Microscopic crystals could soon be zipping drugs around your body, taking them to diseased organs. In the past, this was thought to be impossible - the crystals, which have special magnetic properties, were so small that scientists could not control their movement. But now a team of Chinese researchers has found the solution, and their discovery has opened new applications that could use these crystals to improve - and perhaps even save - many lives. Kezheng Chen and Ji Ma from Quingdou University of Science and Technology, Quingdou, China have published a method of producing superparamagnetic crystals that are much larger than any that have been made before. They recently published their findings in Physics Letters A. If some magnetic materials, such as iron oxides, are small enough - perhaps a few millionths of a millimeter across, smaller than most viruses - they have an unusual property: their magnetization randomly flips as the temperature changes. By applying a magnetic field to these crystals, scientists can make them almost as strongly magnetic as ordinary fridge magnets. It might seem odd, but this is the strongest type of magnetism known. This phenomenon is called superparamagnetism. In theory, superparamagnetic particles could be ideal for drug delivery, as they can be directed to a tumor simply by using a magnetic field. Their tiny size, however, has made them difficult to guide precisely - until now. "The largest superparamagnetic materials that we have been able to make before now were clusters of nanocrystals that were together about a thousand times smaller than these," commented Dr. Chen. "These larger crystals are easier to control using external magnetic fields, and they will not aggregate when those fields are removed, which will make them much more useful in practical applications, including drug delivery." Chen and Ma explained that the high temperature and pressure under which the crystals form made tiny meteorite-like 'micro-particles' of magnetite escape from their surface. This caused the unusual pock-marked appearance of the crystal surfaces and induced a high degree of stress and strain into the lattice of the growing crystals. Crystals that grow under such high stresses and strains form with irregularities and defects in their crystal lattice, and it is these irregularities that are responsible for the unusual magnetic properties of Chen's crystals. Magnetite crystals of a similar size that are grown at a lower temperature and under normal pressure are only very weakly magnetic. This method of making larger superparamagnetic crystals paves the way for the development of superparamagnetic bulk materials that can be reliably controlled by moderate external magnetic forces, revolutionizing drug delivery to tumors and other sites in the body that need to be targeted precisely. And this is just the beginning. Chen's crystals might, for example, be useful in the many engineering projects that need "smart fluids" that change their properties when a magnetic field is applied. These can already be used to make vehicle suspension systems that automatically adjust as road conditions change, increasing comfort and safety, and to build more comfortable and realistic prosthetic limbs. Now that superparamagnetism is no longer restricted to minute particles that are difficult to handle, researchers can start exploring in which ways this can contribute to improving our lives. More information: Ji Ma et al, Discovery of superparamagnetism in sub-millimeter-sized magnetite porous single crystals, Physics Letters A (2016). DOI: 10.1016/j.physleta.2016.07.065


Electrons have three degrees of freedom: spin, orbital, and electric charge. In condensed-matter physics, the study of aggregates formed by multiple atoms and ions, such as crystals and glass, the realization of a state of "quantum spin liquid" in which spin degrees of freedom do not freeze even at very low temperatures is thought to be one of the goals in the field. In perovskite type copper oxide, a typical crystal structure of metal oxide, the possibility of achieving a quantum spin orbital liquid state (figure 1) in which both spin degrees of freedom and orbital degrees of freedom do not freeze even at very low temperatures was suggested. Joint research using high-quality samples, in which this group was involved, elucidated that Jahn-Teller distortion, which shows that the orbital degree of freedom freezes, did not take place at low temperatures. However, there was no direct evidence of a quantum spin orbital liquid state, such as an observation of the orbital quantum dynamics in the spin. Masayuki Hagiwara, Professor at Osaka University, Takehito Nakano, Assistant Professor and Yasuo Nozoe, Professor at Osaka University, in collaboration with Satoru Nakatsuji, Professor at the University of Tokyo and Yibo Han, Associate Professor at Hauzhong University of Science and Technology, examined high-quality single crystals of perovskite-type copper oxide (6H-Ba3CuSb2O9) using an electron spin resonance (ESR) apparatus with a wide frequency range at a strong magnetic field facility in Osaka University. As a result, while at low frequency, orbital degrees of freedom did not freeze at extremely low temperatures, but at high frequency, these orbital degrees of freedom was observed to freeze. These results have clarified that the time scale of orbital quantum fluctuations is about 100 ps below 20 K. This achievement has elucidated the dynamics of a new quantum liquid state, "quantum spin orbital liquid," which was made available through the use of strong magnetic fields for the first time. The realization of the quantum spin orbital liquid state is comparable to that of superconductivity and the superfluidity of helium. These research achievements will make it possible to design new materials for realizing the quantum spin orbital liquid state and will have an effect on the development of materials necessary for the foundation of quantum information control in quantum computers. Explore further: A new class of electron interactions in quantum systems More information: Yibo Han et al. Observation of the orbital quantum dynamics in the spin- hexagonal antiferromagnet , Physical Review B (2015). DOI: 10.1103/PhysRevB.92.180410

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