A Survey of Established Veterinary Clinical Skills Laboratories from Europe and North America:Present Practices and Recent Developments

Hierarchical clustering analysis of all dysregulated genes. (TIF 11970 kb

Water Oxidation on Oxygen-Deficient Barium Titanate: A First-Principles Study

We present a study of the effects of oxygen vacancies (O_vac) on the oxygen evolution reaction (OER) on the TiO₂-terminated (001) surface of cubic BaTiO₃ (cBTO-TiO₂) using spin-polarized DFT+U calculations and the standard (cation-based) four proton-coupled-electron-transfer methodology. We find that the excess electrons associated with O_vac’s are involved in charge transfer (CT) to the intermediate adsorbate species HO*, O*, and HOO* and/or new surface oxygen hole states that we identified. The CT is responsible for an increase in these species’ binding energies to the oxygen-deficient surface (cBTO-TiO_2–<i>x</i>) to an extent consistent with their electronegativity. The much stronger stabilization of HO* and O* compared to HOO* results in an increased overpotential η^OER on the reduced oxide. This result is at odds with experiment that shows a significantly increased efficiency for oxygen-deficient BTO, suggesting that a different mechanism and/or surface must be involved under the experimental conditions. We also identify heretofore unreported HO* and O* intermediate adsorbate structures whereby these species oxidize the surface and a surface oxygen hole is formed adjacent to the adsorption site. We assign the facile surface oxidation to the 2-fold coordination of the surface oxygen atoms in Ti–O–Ti surface moieties and a resulting low work function

Role of Local Carbon Structure Surrounding FeN₄ Sites in Boosting the Catalytic Activity for Oxygen Reduction

Development of effective nonprecious metal and nitrogen codoped carbon catalysts for the oxygen reduction reaction (ORR) requires a fundamental understanding of the mechanisms underlying their catalytic activity. In this study, we employed the first-principles density functional theory calculations to predict some key parameters (such as activation energy for O–O bond breaking and free-energy evolution as a function of electrode potential) of ORR on three FeN₄-type active sites with different local carbon structures. We find that the FeN₄ site surrounded by eight carbon atoms and at the edge of micropores has the lowest activation energy (about 0.20 eV) for O–O bond breaking among the three FeN₄-type active sites for promoting a direct four-electron ORR. Consequently, our computational results suggest that introduction of micropores in the nonprecious metal catalysts could enhance their catalytic activity for ORR through facilitating the formation of FeN₄–C₈ active sites with high specific activity

Observation of the Second-Order Quadrupolar Interaction as a Dominating NMR Relaxation Mechanism in Liquids: The Ultraslow Regime of Motion

We report variable-temperature (VT) ¹⁷O NMR spectra of [5-¹⁷O]-d-glucose in an aqueous solution and in glycerol at 14.1 and 21.1 T. The VT ¹⁷O NMR data cover a wide range of motion for which the molecular rotational correlation time (τ_c) of glucose changes more than 5 orders of magnitude. The observed line width of the ¹⁷O NMR signal for [5-¹⁷O]-d-glucose displays a maximum at ω₀τ_c ≈ 1 and a minimum at ω₀τ_c ≈ 150, where ω₀ is the angular Larmor frequency of ¹⁷O. Under the ultraslow motion condition (i.e., ω₀τ_c > 150), the line width of the observed ¹⁷O NMR signal increases drastically with τ_c, suggesting that the second-order quadrupolar interaction becomes the predominant relaxation mechanism. While this relaxation mechanism has long been predicted by theory, the current study reports the first experimental observation of such a phenomenon. The implications of this new relaxation mechanism on the spectral resolution limit in liquid-state NMR spectroscopy for half-integer spins are discussed

Communities detection in top1 origin network for each decade between 1960 and 2000.

<p>The nodes having the same colour are members of the same component, while the same background shows that they belong to the same community.</p

Extracting international migration top networks from the CIMN in 2000.

<p>Extracting international migration top networks from the CIMN in 2000.</p

sj-pdf-1-imr-10.1177_03000605221123882 - Supplemental material for Refractory postherpetic neuralgia in a multiple myeloma patient with lenalidomide maintenance therapy: a case report

Supplemental material, sj-pdf-1-imr-10.1177_03000605221123882 for Refractory postherpetic neuralgia in a multiple myeloma patient with lenalidomide maintenance therapy: a case report by Xueqin Cao, Gang Wu, Bo Jiao and Xianwei Zhang in Journal of International Medical Research</p

Heteroatom Polymer-Derived 3D High-Surface-Area and Mesoporous Graphene Sheet-Like Carbon for Supercapacitors

Current supercapacitors suffer from low energy density mainly due to the high degree of microporosity and insufficient hydrophilicity of their carbon electrodes. Development of a supercapacitor capable of simultaneously storing as much energy as a battery, along with providing sufficient power and long cycle stability would be valued for energy storage applications and innovations. Differing from commonly studied reduced graphene oxides, in this work we identified an inexpensive heteroatom polymer (polyaniline-PANI) as a carbon/nitrogen precursor, and applied a controlled thermal treatment at elevated temperature to convert PANI into 3D high-surface-area graphene-sheet-like carbon materials. During the carbonization process, various transition metals including Fe, Co, and Ni were added, which play critical roles in both catalyzing the graphitization and serving as pore forming agents. Factors including post-treatments, heating temperatures, and types of metal were found crucial for achieving enhanced capacitance performance on resulting carbon materials. Using FeCl₃ as precursor along with optimal heating temperature 1000 °C and mixed acid treatment (HCl+HNO₃), the highest Brunauer–Emmett–Teller (BET) surface area of 1645 m²g^–1 was achieved on the mesopore dominant graphene-sheet-like carbon materials. The unique morphologies featured with high-surface areas, dominant mesopores, proper nitrogen doping, and 3D graphene-like structures correspond to remarkably enhanced electrochemical specific capacitance up to 478 Fg^–1 in 1.0 M KOH at a scan rate of 5 mV s^–1. Furthermore, in a real two-electrode system of a symmetric supercapacitor, a specific capacitance of 235 Fg^–1 using Nafion binder is obtained under a current density of 1 Ag^–1 by galvanostatic charge–discharge tests in 6.0 M KOH. Long-term cycle stability up to 5000 cycles by using PVDF binder in electrode was systematically evaluated as a function of types of metals and current densities

Experimental Verification of the Theory of Nuclear Quadrupole Relaxation in Liquids over the Entire Range of Molecular Tumbling Motion

Nuclear magnetic resonance (NMR) spectra of quadrupolar nuclei (<i>I</i> > 1/2) in liquids often consist of broad resonances, making it difficult to obtain useful chemical information. The poor NMR spectral resolution commonly observed for quadrupolar nuclei is a direct consequence of nuclear quadrupole relaxation processes. Although all key aspects of nuclear quadrupole relaxation processes have been known for decades within the framework of the Redfield relaxation theory, direct experimental NMR relaxation data that cover a wide range of molecular motion in liquids for quadrupolar nuclei are generally lacking. Here we report a complete set of experimental nuclear quadrupole relaxation data that are obtained for ¹⁷O, a half-integer quadrupolar nucleus, over the entire range of molecular motion within the limit of the Redfield theory. A general approach utilizing the quadrupole relaxation properties in the slow motion limit will be particularly beneficial for studies of quadrupolar nuclei in biomolecules of medium and large sizes

H‑NOX from <i>Clostridium botulinum</i>, like H‑NOX from <i>Thermoanaerobacter tengcongensis</i>, Binds Oxygen but with a Less Stable Oxyferrous Heme Intermediate

Heme nitric oxide/oxygen binding protein isolated from the obligate anaerobe <i>Clostridium botulinum</i> (<i>Cb</i> H-NOX) was previously reported to bind NO with a femtomolar <i>K</i>_D (Nioche, P. et al. Science 2004, 306, 1550–1553). On the other hand, no oxyferrous <i>Cb</i> H-NOX was observed despite full conservation of the key residues that stabilize the oxyferrous complex in the H-NOX from <i>Thermoanaerobacter tengcongensis</i> (<i>Tt</i> H-NOX) (the same study). In this study, we re-measured the kinetics/affinities of <i>Cb</i> H-NOX for CO, NO, and O₂. <i>K</i>_D(CO) for the simple one-step equilibrium binding was 1.6 × 10^–7 M. The <i>K</i>_D(NO) of <i>Cb</i> H-NOX was 8.0 × 10^–11 M for the first six-coordinate NO complex, and the previous femtomolar <i>K</i>_D(NO) was actually an apparent <i>K</i>_D for its multiple-step NO binding. An oxyferrous <i>Cb</i> H-NOX was clearly observed with a <i>K</i>_D(O₂) of 5.3 × 10^–5 M, which is significantly higher than <i>Tt</i> H-NOX’s <i>K</i>_D(O₂) = 4.4 × 10^–8 M. The gaseous ligand binding of <i>Cb</i> H-NOX provides another supportive example for the “sliding scale rule” hypothesis (Tsai, A.-L. et al. Antioxid. Redox Signal. 2012, 17, 1246–1263), and the presence of hydrogen bond donor Tyr139 in <i>Cb</i> H-NOX selectively enhanced its affinity for oxygen