Simulation of Wave in Hypo-Elastic-Plastic Solids Modeled by Eulerian Conservation Laws

This paper reports a theoretical and numerical framework to model nonlinear waves in elastic-plastic solids. Formulated in the Eulerian frame, the governing equations employed include the continuity equation, the momentum equation, and an elastic-plastic constitutive relation. The complete governing equations are a set of first-order, fully coupled partial differential equations with source terms. The primary unknowns are velocities and deviatoric stresses. By casting the governing equations into a vector-matrix form, we derive the eigenvalues of the Jacobian matrix to show the wave speeds. The eigenvalues are also used to calculate the Courant number for numerical stability. The model equations are solved using the Space-Time Conservation Element and Solution Element (CESE) method. The approach is validated by comparing our numerical results to an analytical solution for the special case of longitudinal wave motion.Comment: 34 pages, 11 figure

The UCSC Archaeal Genome Browser

As more archaeal genomes are sequenced, effective research and analysis tools are needed to integrate the diverse information available for any given locus. The feature-rich UCSC Genome Browser, created originally to annotate the human genome, can be applied to any sequenced organism. We have created a UCSC Archaeal Genome Browser, available at , currently with 26 archaeal genomes. It displays G/C content, gene and operon annotation from multiple sources, sequence motifs (promoters and Shine-Dalgarno), microarray data, multi-genome alignments and protein conservation across phylogenetic and habitat categories. We encourage submission of new experimental and bioinformatic analysis from contributors. The purpose of this tool is to aid biological discovery and facilitate greater collaboration within the archaeal research community

Novel DNA methylation profiles associated with key gene regulation and transcription pathways in blood and placenta of growth-restricted neonates

BB/H012494/1/ Biotechnology and Biological Sciences Research Counci

Low Intensity, High Frequency Vibration Training to Improve Musculoskeletal Function in a Mouse Model of Duchenne Muscular Dystrophy

The objective of the study was to determine if low intensity, high frequency vibration training impacted the musculoskeletal system in a mouse model of Duchenne muscular dystrophy, relative to healthy mice. Three-week old wildtype (n = 26) and mdx mice (n = 22) were randomized to non-vibrated or vibrated (45 Hz and 0.6 g, 15 min/d, 5 d/wk) groups. In vivo and ex vivo contractile function of the anterior crural and extensor digitorum longus muscles, respectively, were assessed following 8 wks of vibration. Mdx mice were injected 5 and 1 days prior to sacrifice with Calcein and Xylenol, respectively. Muscles were prepared for histological and triglyceride analyses and subcutaneous and visceral fat pads were excised and weighed. Tibial bones were dissected and analyzed by micro-computed tomography for trabecular morphometry at the metaphysis, and cortical geometry and density at the mid-diaphysis. Three-point bending tests were used to assess cortical bone mechanical properties and a subset of tibiae was processed for dynamic histomorphometry. Vibration training for 8 wks did not alter trabecular morphometry, dynamic histomorphometry, cortical geometry, or mechanical properties (P≥0.34). Vibration did not alter any measure of muscle contractile function (P≥0.12); however the preservation of muscle function and morphology in mdx mice indicates vibration is not deleterious to muscle lacking dystrophin. Vibrated mice had smaller subcutaneous fat pads (P = 0.03) and higher intramuscular triglyceride concentrations (P = 0.03). These data suggest that vibration training at 45 Hz and 0.6 g did not significantly impact the tibial bone and the surrounding musculature, but may influence fat distribution in mice

Evidence Favoring Molybdenum−Carbon Bond Formation in Xanthine Oxidase Action: \u3csup\u3e17\u3c/sup\u3eO- and \u3csup\u3e13\u3c/sup\u3eC-ENDOR and Kinetic Studies

The reaction mechanism of the molybdoenzyme xanthine oxidase has been further investigated by 13C and 17O ENDOR of molybdenum(V) species and by kinetic studies of exchange of oxygen isotopes. Three EPR signal-giving species were studied:  (i) Very Rapid, a transient intermediate in substrate turnover, (ii) Inhibited, the product of an inhibitory side reaction with aldehyde substrates, and (iii) Alloxanthine, a species formed by reaction of reduced enzyme with the inhibitor, alloxanthine. The Very Rapid signal was developed either with [8-13C]xanthine or with 2-oxo-6-methylpurine using enzyme equilibrated with [17O]H2O. The Inhibited signal was developed with 2H13C2HO and the Alloxanthine signal by using [17O]H2O. Estimates of Mo−C distances were made, from the anisotropic components of the 13C-couplings, by corrected dipolar coupling calculations and by back-calculation from assumed possible structures. Estimated distances in the Inhibited and Very Rapid species were about 1.9 and less than 2.4 Å, respectively. A Mo−C bond in the Inhibited species is very strongly suggested, presumably associated with side-on bonding to molybdenum of the carbonyl of the aldehyde substrate. For the Very Rapid species, a Mo−C bond is highly likely. Coupling from a strongly coupled 17O, not in the form of an oxo group, and no coupling from other oxygens was detected in the Very Rapid species. No coupled oxygens were detected in the Alloxanthine species. That the coupled oxygen of the Very Rapid species is the one that appears in the product uric acid molecule was confirmed by new kinetic data. It is concluded that this oxygen of the Very Rapid species does not, as frequently assumed, originate from the oxo group of the oxidized enzyme. A new turnover mechanism is proposed, not involving direct participation of the oxo ligand group, and based on that of Coucouvanis et al. [Coucouvanis, D., Toupadakis, A., Lane, J. D., Koo, S. M., Kim, C. G., Hadjikyriacou, A. (1991) J. Am. Chem. Soc. 113, 5271−5282]. It involves formal addition of the elements of the substrate (e.g., xanthine) across the MoS double bond, to give a Mo(VI) species. This is followed by attack of a “buried” water molecule (in the vicinity of molybdenum and perhaps a ligand of it) on the bound substrate carbon, to give an intermediate that on intramolecular one-electron oxidation gives the Very Rapid species. The latter, in keeping with the 13C, 17O, and 33S couplings, is presumed to have the 8-CO group of the uric acid product molecule bonded side-on to molybdenum, with the sulfido molybdenum ligand retained, as in the oxidized enzyme

Correction: Identification of specific calcitonin-like receptor residues important for calcitonin gene-related peptide high affinity binding

This is a correction article. After publication of this work [1], we became aware of the fact that Robert C. Speth was not included as an author. Dr. Speth put a considerable amount of time and effort into developing and preparing the radiopeptide used to carry out the radioligand binding studies reported in this manuscript and therefore should have originally been included as an author. We apologize to Dr. Speth for any inconvenience that this oversight might have caused and thank him for his invaluable contribution to this project

Multi-nuclear, high-pressure, operando FlowNMR spectroscopic study of Rh/PPh3 – catalysed hydroformylation of 1-hexene

The hydroformylation of 1-hexene with 12 bar of 1 : 1 H2/CO in the presence of the catalytic system [Rh(acac)(CO)2]/PPh3 was successfully studied by real-time multinuclear high-resolution FlowNMR spectroscopy at 50 °C. Quantitative reaction progress curves that yield rates as well as chemo- and regioselectivities have been obtained with varying P/Rh loadings. Dissolved H2 can be monitored in solution to ensure true operando conditions without gas limitation. 31P{1H} and selective excitation 1H pulse sequences have been periodically interleaved with 1H FlowNMR measurements to detect Rh–phosphine intermediates during the catalysis. Stopped-flow experiments in combination with diffusion measurements and 2D heteronuclear correlation experiments showed the known tris-phosphine complex [RhH(CO)(PPh3)3] to generate rapidly exchanging isomers of the bis-phosphine complex [Rh(CO)2(PPh3)2] under CO pressure that directly enter the catalytic cycle. A new mono-phosphine acyl complex has been identified as an in-cycle reaction intermediate