Breindel A.,University of Rochester |
Sun D.,New Mexico Resonance |
Sen S.,State University of New York at Buffalo
Applied Physics Letters | Year: 2011
Sustained ability to absorb impulses at varied temperatures using light, hard materials and at length scales of few centimeters has been a challenge. The tapered chains while effective have been difficult to construct for applications. Here we build on Hong's granular protector concept to show that strong inertial mismatches due to alternate sets of few massive and light grains in elastically matched monosized granular alignments seem promising in absorbing impulses across millisecond time scales within a few centimeters. We propose a system which could find applications in the context of the construction and automobile industries, in combat, and elsewhere. © 2011 American Institute of Physics.
Avalos E.,Chung Yuan Christian University |
Sun D.,New Mexico Resonance |
Doney R.L.,U.S. Army |
Sen S.,State University of New York at Buffalo
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011
Here we consider dynamical problems as in linear response theory but for purely nonlinear systems where acoustic propagation is prohibited by the potential, e.g., the case of an alignment of elastic grains confined between walls. Our simulations suggest that in the absence of acoustic propagation, the system relaxes using only solitary waves and the eventual state does not resemble an equilibrium state. Further, the studies reveal that multiple perturbations could give rise to hot and cold spots in these systems. We first use particle dynamics based simulations to understand how one of the two unequal colliding solitary waves in the chain can gain energy. Specifically, we find that for head-on collisions the smaller wave gains energy, whereas when a more energetic wave overtakes a less energetic wave, the latter gains energy. The balance between the rate at which the solitary waves break down and the rate at which they grow eventually makes it possible for the system to reach a peculiar equilibriumlike phase that is characteristic of these purely nonlinear systems. The study of the features and the robustness of the fluctuations in time has been addressed next. A particular characteristic of this equilibriumlike or quasiequilibrium phase is that very large energy fluctuations are possible-and by very large, we mean that the energy can vary between zero and several times the average energy per grain. We argue that the magnitude of the fluctuations depend on the nature of the nonlinearity in the potential energy function and the feature that any energy must eventually travel as a compact solitary wave in these systems where the solitary wave energies may vary widely. In closing we address whether these fluctuations are peculiar to one dimension or can exist in higher dimensions. The study hence raises the following intriguing possibility. Are there physical or biological systems where these kinds of nonlinear forces exist, and if so, can such large fluctuations actually be seen? Implications of the study are briefly discussed. © 2011 American Physical Society.
Fransen J.C.,Loyola University Chicago |
Zuhl M.,Central Michigan University |
Kerksick C.M.,Lindenwood University |
Cole N.,University of New Mexico |
And 3 more authors.
European Journal of Applied Physiology | Year: 2015
Purpose: This study investigated the effect of creatine (CR) supplementation during cast-immobilization to preserve skeletal muscle total work, power and intramuscular phosphocreatine (PCr) kinetics during dynamic exercise. Methods: Twenty-five active individuals (24 ± 4 years,) performed wrist flexion exercise within a 1.9 Tesla superconducting magnet before and after 1 week of cast-immobilization. An incremental protocol to fatigue and two constant load (CL1 and CL2) exercise bouts were performed. While casted, participants consumed either 20 g day−1 of CR or a placebo (PLA). 31P magnetic resonance spectroscopy was used to quantify in vivo intramuscular PCr levels. Results: No significant group × time interaction effects were found for work or power throughout all exercise bouts. Total work was significantly reduced over time in both groups (p = 0.049) during the incremental exercise bout. Work production in CL1 tended (p = 0.073) to attenuate in the CR group, compared to PLA. No changes were observed in CL2. Baseline PCr significantly decreased with casting in PLA (PRE: 26.6 ± 6.3 vs. POST: 22.5 ± 5.6 mM kg−1 wet muscle, p = 0.003). No change (p = 0.31) was observed in the CR group. Changes in work production were significantly correlated with changes in resting PCr in CR (r = −0.63, p = 0.021) but not PLA (r = −0.36, p = 0.26) group. Conclusions: Results suggest decreases in short-term endurance may be due to alternations of PCr status and/or metabolism. More research is needed to fully determine the efficacy of CR supplementation during short-term immobilization. © 2015, Springer-Verlag Berlin Heidelberg.
Sanfratello L.,New Mexico Resonance |
Sanfratello L.,University of New Mexico |
Zhang J.,Duke University |
Zhang J.,Indiana University - Purdue University Fort Wayne |
And 3 more authors.
Granular Matter | Year: 2011
The distribution of the lengths of force chains in 2D granular assemblies of photoelastic disks was found to decay exponentially, with the decay length a quantitative measure of the way force is applied to the system. A plausibility argument is provided for why this statistic displays an exponential decay. © 2011 Springer-Verlag.
Kuethe D.O.,New Mexico Resonance |
McBride A.,University of New Mexico |
Altobelli S.A.,New Mexico Resonance
Journal of Magnetic Resonance | Year: 2012
Nuclear Magnetic Resonance Images (MRIs) of the velocity of water droplets and velocity of the suspending gas, hexafluoroethane, are presented for a vertical and horizontal mist pipe flow. In the vertical flow, the upward velocity of the droplets is clearly slower than the upward velocity of the gas. The average droplet size calculated from the average falling velocity in the upward flow is larger than the average droplet size of mist drawn from the top of the pipe measured with a multi-stage aerosol impactor. Vertical flow concentrates larger particles because they have a longer transit time through the pipe. In the horizontal flow there is a gravity-driven circulation with high-velocity mist in the lower portion of the pipe and low-velocity gas in the upper portion. MRI has the advantages that it can image both phases and that it is unperturbed by optical opacity. A drawback is that the droplet phase of mist is difficult to image because of low average spin density and because the signal from water coalesced on the pipe walls is high. To our knowledge these are the first NMR images of mist. © 2012 Elsevier Inc. All rights reserved.
Adolphi N.L.,University of New Mexico |
Butler K.S.,University of New Mexico |
Lovato D.M.,University of New Mexico |
Tessier T.E.,LLC LLC |
And 12 more authors.
Contrast Media and Molecular Imaging | Year: 2012
Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by superconducting quantum interference device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 (breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125 000 nanoparticle-labeled cells at 3cm from the SQUID sensors. T2-weighted MRI yielded a detection limit of 15 600 cells in a 150μl volume, with r1=1.1mm-1s-1 and r2=166mm-1s-1. Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies. © 2012 John Wiley & Sons, Ltd.
Nakashima Y.,Japan National Institute of Advanced Industrial Science and Technology |
Mitsuhata Y.,Japan National Institute of Advanced Industrial Science and Technology |
Nishiwaki J.,Japan National Institute of Advanced Industrial Science and Technology |
Kawabe Y.,Japan National Institute of Advanced Industrial Science and Technology |
And 2 more authors.
Water, Air, and Soil Pollution | Year: 2011
Non-destructive measurements of contaminated soil core samples are desirable prior to destructive measurements because they allow obtaining gross information from the core samples without touching harmful chemical species. Medical X-ray computed tomography (CT) and time-domain low-field nuclear magnetic resonance (NMR) relaxometry were applied to non-destructive measurements of sandy soil core samples from a real site contaminated with heavy oil. The medical CT visualized the spatial distribution of the bulk density averaged over the voxel of 0.31∈×∈0.31∈×∈2 mm3. The obtained CT images clearly showed an increase in the bulk density with increasing depth. Coupled analysis with in situ time-domain reflectometry logging suggests that this increase is derived from an increase in the water volume fraction of soils with depth (i.e., unsaturated to saturated transition). This was confirmed by supplementary analysis using high-resolution micro-focus X-ray CT at a resolution of ∼10 μm, which directly imaged the increase in pore water with depth. NMR transverse relaxation waveforms of protons were acquired non-destructively at 2.7 MHz by the Carr-Purcell-Meiboom- Gill (CPMG) pulse sequence. The nature of viscous petroleum molecules having short transverse relaxation times (T2) compared to water molecules enabled us to distinguish the water-saturated portion from the oil-contaminated portion in the core sample using an M 0-T2 plot, where M 0 is the initial amplitude of the CPMG signal. The present study demonstrates that non-destructive core measurements by medical X-ray CT and low-field NMR provide information on the groundwater saturation level and oil-contaminated intervals, which is useful for constructing an adequate plan for subsequent destructive laboratory measurements of cores. © 2010 The Author(s).
PubMed | New Mexico Resonance
Type: | Journal: Journal of magnetic resonance (San Diego, Calif. : 1997) | Year: 2012
Nuclear Magnetic Resonance Images (MRIs) of the velocity of water droplets and velocity of the suspending gas, hexafluoroethane, are presented for a vertical and horizontal mist pipe flow. In the vertical flow, the upward velocity of the droplets is clearly slower than the upward velocity of the gas. The average droplet size calculated from the average falling velocity in the upward flow is larger than the average droplet size of mist drawn from the top of the pipe measured with a multi-stage aerosol impactor. Vertical flow concentrates larger particles because they have a longer transit time through the pipe. In the horizontal flow there is a gravity-driven circulation with high-velocity mist in the lower portion of the pipe and low-velocity gas in the upper portion. MRI has the advantages that it can image both phases and that it is unperturbed by optical opacity. A drawback is that the droplet phase of mist is difficult to image because of low average spin density and because the signal from water coalesced on the pipe walls is high. To our knowledge these are the first NMR images of mist.