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Proceedings of the National Academy of... Feb 2020We study the manifestation of the Nernst effect in the Corbino disk subjected to the normal external magnetic field and to the radial temperature gradient. The Corbino...
We study the manifestation of the Nernst effect in the Corbino disk subjected to the normal external magnetic field and to the radial temperature gradient. The Corbino geometry offers a precious opportunity for the direct measurement of the magnetization currents that are masked by kinetic contributions to the Nernst current in the conventional geometry. The magnetization currents, also referred to as the edge currents, are independent on the conductivity of the sample which is why they can be conveniently described within the thermodynamic approach. They can be related to the Landau thermodynamic potential for an infinite system. We demonstrate that the observable manifestation of this, purely thermodynamic, Nernst effect consists in the strong oscillations of the magnetic field measured in the center of the disk as a function of the external field. The oscillations depend on the temperature difference at the edges of the disk. Dirac fermions and 2D electrons with a parabolic spectrum are characterized by oscillations of different phase and frequency. We predict qualitatively different power dependencies of the magnitude of the Nernst signal on the chemical potential for normal and Dirac carriers.
PubMed: 31992642
DOI: 10.1073/pnas.1916567117 -
Journal of Orthopaedic Case Reports Sep 2022While the body of research investigating anterior cervical disk fusion (ACDF) for symptomatic cervical disk herniations in high-level athletes is large, evidence for...
INTRODUCTION
While the body of research investigating anterior cervical disk fusion (ACDF) for symptomatic cervical disk herniations in high-level athletes is large, evidence for cervical disk replacement (CDR) is sparse. The amount of patients able to return to sport after an ACDF is estimated to be 73.5%, causing surgeons to search for alternatives with better outcomes in this population. This case report describes the successful treatment of a symptomatic collegiate American football player with C6-C7 disk herniation and C5-C6 central canal stenosis.
CASE REPORT
This is a 21-year-old American football safety who underwent a C5-6 and C6-7 cervical disk arthroplasty. Three weeks postoperatively, the patient demonstrated nearly complete resolution of weakness, full resolution of radiculopathy, and normal cervical range of motion in all planes.
CONCLUSION
The CDR may be considered as an alternative to the ACDF in the treatment of high-level contact athletes. Compared to the ACDF, CDR has been shown in prior studies to decrease the long-term risk of adjacent segment degeneration. Future studies comparing ACDF to CDR in the high-level contact sport athlete population are needed. CDR appears to be a promising surgical intervention for symptomatic patients in this population.
PubMed: 36873322
DOI: 10.13107/jocr.2022.v12.i09.3008 -
Antibiotics (Basel, Switzerland) Apr 2021has recently emerged as a cause of life-threatening infections. This study compared the results of antimicrobial susceptibility testing (AST) conducted for through...
has recently emerged as a cause of life-threatening infections. This study compared the results of antimicrobial susceptibility testing (AST) conducted for through different methods. isolates collected between January 2005 and June 2019 were examined for their susceptibility to 14 antimicrobial agents by using disk diffusion, gradient diffusion (Etest; bioMérieux S.A., Marcy l'Etoile, France) and agar dilution methods. The agar dilution method was the reference assay. According to the agar dilution method, the isolates exhibited the highest susceptibility to minocycline (100%), doxycycline (97.6%), rifampin (95.2%), and levofloxacin (78.6%). A very major error rate of >1.5% was observed for nine antibiotics tested using the disk diffusion method. The overall categorical agreement rate between the disk diffusion and agar dilution methods was 74.8%, and ceftazidime, minocycline, levofloxacin, and rifampin met the minimum requirements for discrepancy and agreement rates. The Etest method tended to produce lower log minimum inhibitory concentrations for the antibiotics, except for trimethoprim-sulfamethoxazole and rifampin; the method resulted in very major errors for nine antibiotics. The overall essential and categorical agreement rates between the Etest and agar dilution methods were 67.3% and 76.1%, respectively. The Etest method demonstrated acceptable discrepancy and agreement rates for ceftazidime, minocycline, doxycycline, levofloxacin, and rifampin. AST results obtained through the disk diffusion and Etest methods for multiple antibiotics differed significantly from those obtained using the agar dilution method. These two assays should not be a routine alternative for AST for .
PubMed: 33923659
DOI: 10.3390/antibiotics10040450 -
Biomolecules & Biomedicine Jul 2023Intervertebral disk degeneration remains one of the most challenging health problems. In the current study, allopurinol was loaded into the chitosan nanoparticles and...
Intervertebral disk degeneration remains one of the most challenging health problems. In the current study, allopurinol was loaded into the chitosan nanoparticles and then incorporated into chitosan/alginate hydrogels and then further studied for its disk regeneration potential in a rat model. In vitro studies were performed to characterize the hydrogel system, including scanning electron microscopy, cell viability assay, cytoprotection assay, cell migration assay, swelling assay, and drug release assay. In vivo study was performed in a rat model of the intervertebral disk injury. Animal studies showed that allopurinol-loaded hydrogels had significantly higher disk regeneration potential compared with other experimental groups. The gene expression studies showed that the animals treated with allopurinol-loaded hydrogel had significantly higher tissue expression levels of type I and type II collagen genes than other groups. Furthermore, the tissue expression levels of nuclear factor κB (NF-κB) and glutathione peroxidase (GPx) genes were significantly lower in this group. The relative expression levels of type I collagen, type II collagen, NF-κB, and GPx genes in the allopurinol-loaded hydrogel group were 2.77 ± 0.2%, 2.86 ± 0.25%, 0.58 ± 0.03%, and 0.45 ± 0.02%, respectively. We showed for the first time that allopurinol-loaded hydrogel promoted intervertebral disk repair, which could be due to its potential to modulate oxidative stress, reduce inflammation, and improve matrix synthesis.
Topics: Rats; Animals; Hydrogels; Chitosan; Allopurinol; NF-kappa B; Alginates; Intervertebral Disc; Collagen Type II; Regeneration
PubMed: 36786280
DOI: 10.17305/bb.2022.8550 -
Biomicrofluidics May 2022Nowadays, centrifugal microfluidic platforms are finding wider acceptance for implementing point-of-care assays due to the simplicity of the controls, the versatility of...
Nowadays, centrifugal microfluidic platforms are finding wider acceptance for implementing point-of-care assays due to the simplicity of the controls, the versatility of the fluidic operations, and the ability to create a self-enclosed system, thus minimizing the risk of contamination for either the sample or surroundings. Despite these advantages, one of the inherent weaknesses of CD microfluidics is that all the sequential fluidic chambers and channels must be positioned radially since the centrifugal force acts from the center of the disk outward. Implementation of schemes where the liquid can be rerouted from the disk periphery to the disk center would significantly increase the utility of CD platforms and increase the rational utilization of the real estate on the disk. The present study outlines a novel utilization of elastic membranes covering fluidic chambers to implement inward pumping whereby the fluid is returned from the disk periphery to the center of the disk. When the disk revolves at an angular velocity of 3600 rpm, liquid enters the chamber covered by the elastic membrane. This membrane is deflected upward by liquid, storing energy like a compressed spring. When the angular velocity of the disk is reduced to 180 rpm and thus the centrifugal force is diminished, the elastic membrane pushes the liquid from the chamber inward, closer to the center of the disk. There are two channels leading from the elastic membrane-covered reservoir-one channel has a higher fluidic resistance and the other (wider) has a lower fluidic resistance. The geometry of these two channels determines the fluidic path inward (toward the center of the disk). Most of the liquid travels through the recirculating channel with lower resistance. We demonstrated an inward pumping efficiency in the range of 78%-89%. Elastic membrane-driven inward pumping was demonstrated for the application of enhanced fluid mixing. Additionally, to demonstrate the utility of the proposed pumping mechanism for multi-step assays on the disk, we implemented and tested a disk design that combines plasma separation and inward pumping.
PubMed: 35607410
DOI: 10.1063/5.0089112 -
Nature Mar 2022The formation of our Milky Way can be split up qualitatively into different phases that resulted in its structurally different stellar populations: the halo and the disk...
The formation of our Milky Way can be split up qualitatively into different phases that resulted in its structurally different stellar populations: the halo and the disk components. Revealing a quantitative overall picture of our Galaxy's assembly requires a large sample of stars with very precise ages. Here we report an analysis of such a sample using subgiant stars. We find that the stellar age-metallicity distribution p(τ, [Fe/H]) splits into two almost disjoint parts, separated at age τ ≃ 8 Gyr. The younger part reflects a late phase of dynamically quiescent Galactic disk formation with manifest evidence for stellar radial orbit migration; the other part reflects the earlier phase, when the stellar halo and the old α-process-enhanced (thick) disk formed. Our results indicate that the formation of the Galaxy's old (thick) disk started approximately 13 Gyr ago, only 0.8 Gyr after the Big Bang, and 2 Gyr earlier than the final assembly of the inner Galactic halo. Most of these stars formed around 11 Gyr ago, when the Gaia-Sausage-Enceladus satellite merged with our Galaxy. Over the next 5-6 Gyr, the Galaxy experienced continuous chemical element enrichment, ultimately by a factor of 10, while the star-forming gas managed to stay well mixed.
PubMed: 35322254
DOI: 10.1038/s41586-022-04496-5 -
Asian Spine Journal Feb 2022Symptomatic disk degeneration is characterized by early pathological changes in the morphological, biochemical, and biomechanical properties of the intervertebral disc...
Preventive and Restorative Responses of Broccoli Sprouts on Biomechanical Structures, Histomorphometric, and Gene Expression Levels of Degenerated Intervertebral Disc in Rabbit Model.
STUDY DESIGN
Symptomatic disk degeneration is characterized by early pathological changes in the morphological, biochemical, and biomechanical properties of the intervertebral disc (IVD). Several methods that can be used to resolve this condition are being researched.
PURPOSE
The present study was designed to examine the preventive and restorative properties of broccoli sprouts extracts in an annular puncture rabbit model of IVD degeneration.
OVERVIEW OF LITERATURE
IVD degeneration is closely associated with low back pain. A degenerated IVD is cytoarchitecturally characterized by a reduction in cell number, morphological changes in the disk tissue, and changes in the extracellular matrix contents. Methods, such as imaging and biochemical characterization, have been used for distinguishing between degenerated disk and non-degenerated disk.
METHODS
Twenty New Zealand white rabbits (weighing approximately 2.0-3.5 kg) were divided into four groups (n=5). Group 1 received 50 mg/kg of normal saline solution orally for 4 weeks; group 2 received 50 mg/kg of normal saline solution immediately after puncture for 4 weeks; group 3 received 300 mg/kg of aqueous extract of broccoli sprouts orally immediately after puncture for 4 weeks; and group 4 received 300 mg/kg of aqueous extract of broccoli sprouts after 4 weeks of puncture for another 4 weeks. After the experiment, the disk height index (DHI), histomorphometry, and gene expression level were measured and analyzed.
RESULTS
The photomicrograph showed that the histological features of the punctured-treated groups (groups 3 and 4) were more similar to those of the non-punctured group than those of the punctured non-treated group. There was a significant difference in the DHI and relative gene expression levels among the non-treated punctured groups compared with those of the non-punctured and punctured-treated groups, respectively.
CONCLUSIONS
This study shows that the aqueous extract of broccoli sprouts exerts preventive and restorative effects in a rabbit model with disk degeneration.
PubMed: 33934586
DOI: 10.31616/asj.2020.0479 -
Materials (Basel, Switzerland) Jun 2023Thermopower and the Lorentz number for an edge-free (Corbino) graphene disk in the quantum Hall regime is calculated within the Landauer-Büttiker formalism. By varying...
Thermopower and the Lorentz number for an edge-free (Corbino) graphene disk in the quantum Hall regime is calculated within the Landauer-Büttiker formalism. By varying the electrochemical potential, we find that amplitude of the Seebeck coefficient follows a modified Goldsmid-Sharp relation, with the energy gap defined by the interval between the zero and the first Landau levels in bulk graphene. An analogous relation for the Lorentz number is also determined. Thus, these thermoelectric properties are solely defined by the magnetic field, the temperature, the Fermi velocity in graphene, and fundamental constants including the electron charge, the Planck and Boltzmann constants, being independent of the geometric dimensions of the system. This suggests that the Corbino disk in graphene may operate as a thermoelectric thermometer, allowing to measure small temperature differences between two reservoirs, if the mean temperature magnetic field are known.
PubMed: 37374435
DOI: 10.3390/ma16124250 -
The Journal of General Physiology Aug 2023Sodium (Na+) current is responsible for the rapid depolarization of cardiac myocytes that triggers the cardiac action potential upstroke. Recent studies have illustrated...
Sodium (Na+) current is responsible for the rapid depolarization of cardiac myocytes that triggers the cardiac action potential upstroke. Recent studies have illustrated the presence of multiple pools of Na+ channels with distinct biophysical properties and subcellular localization, including clustering of channels at the intercalated disk and along the lateral membrane. Computational studies predict that Na+ channel clusters at the intercalated disk can regulate cardiac conduction via modulation of the narrow intercellular cleft between electrically coupled myocytes. However, these studies have primarily focused on the redistribution of Na+ channels between intercalated disk and lateral membranes and have not considered the distinct biophysical properties of the Na+ channel subpopulations. In this study, we use computational modeling to simulate computational models of single cardiac cells and one-dimensional cardiac tissues and predict the function of distinct Na+ channel subpopulations. Single-cell simulations predict that a subpopulation of Na+ channels with shifted steady-state activation and inactivation voltage dependency promotes an earlier action potential upstroke. In cardiac tissues that account for distinct subcellular spatial localization, simulations predict that shifted Na+ channels contribute to faster and more robust conduction in response to changes in tissue structure (i.e., cleft width), gap junctional coupling, and rapid pacing rates. Simulations predict that the intercalated disk-localized shifted Na+ channels contribute proportionally more to total Na+ charge than lateral membrane-localized Na+ channels. Importantly, our work supports the hypothesis that Na+ channel redistribution may be a critical mechanism by which cells can respond to perturbations to support fast and robust conduction.
Topics: Myocardium; Myocytes, Cardiac; Sodium Channels; Action Potentials; Gap Junctions
PubMed: 37285024
DOI: 10.1085/jgp.202313382 -
Polish Journal of Microbiology Sep 2021This study was conducted to develop a cheap, rapid, and accurate modified combined-disk test (mCDT) approach to detect and differentiate KPC and MBL carbapenemases among...
This study was conducted to develop a cheap, rapid, and accurate modified combined-disk test (mCDT) approach to detect and differentiate KPC and MBL carbapenemases among clinical carbapenem-resistant Enterobacterales (CRE) isolates and simultaneously distinguish them from carbapenem-susceptible Enterobacterales (CSE) isolates. A total of 163 CRE and 90 third-generation cephalosporin-resistant Enterobacterales isolates were tested using imipenem and meropenem disks and different concentrations of carbapenemase inhibitors. The optimal sensitivity and specificity for detecting KPC carbapenemase were 97.2% and 100%, respectively. The sensitivity and specificity for detecting MBL carbapenemase were 100% and 100% with imipenem or meropenem and carbapenemase inhibitors within six hours. The inhibitory zone diameter of 18 mm for imipenem or meropenem disks without inhibitor could distinguish CRE from CSE isolates. Therefore, this mCDT approach may be a useful tool in clinical laboratories to detect CRE isolates and differentiate KPC and MBL producers, which is beneficial for patient management and hospital infection prevention and control.
Topics: Bacterial Proteins; Bacteriological Techniques; Drug Resistance, Bacterial; Enterobacteriaceae; Enzyme Inhibitors; Imipenem; Meropenem; beta-Lactamases
PubMed: 34584532
DOI: 10.33073/pjm-2021-036