2,494 research outputs found
Field Tests of Some Liming Treatments for Growing Burley Tobacco on Acid Soils
A major problem in the production of tobacco on acid soils in Kentucky is manganese toxicity, despite the fact that it can be easily prevented. Since manganese toxicity is caused by high levels of soil acidity, prevention of soil acidity by liming is the best method of control. And soil testing is the only way to determine how acid a field has become
Goldstone-type fluctuations and their implications for the amorphous solid state
In sufficiently high spatial dimensions, the formation of the amorphous (i.e.
random) solid state of matter, e.g., upon sufficent crosslinking of a
macromolecular fluid, involves particle localization and, concommitantly, the
spontaneous breakdown of the (global, continuous) symmetry of translations.
Correspondingly, the state supports Goldstone-type low energy, long wave-length
fluctuations, the structure and implications of which are identified and
explored from the perspective of an appropriate replica field theory. In terms
of this replica perspective, the lost symmetry is that of relative translations
of the replicas; common translations remain as intact symmetries, reflecting
the statistical homogeneity of the amorphous solid state. What emerges is a
picture of the Goldstone-type fluctuations of the amorphous solid state as
shear deformations of an elastic medium, along with a derivation of the shear
modulus and the elastic free energy of the state. The consequences of these
fluctuations -- which dominate deep inside the amorphous solid state -- for the
order parameter of the amorphous solid state are ascertained and interpreted in
terms of their impact on the statistical distribution of localization lengths,
a central diagnostic of the the state. The correlations of these order
parameter fluctuations are also determined, and are shown to contain
information concerning further diagnostics of the amorphous solid state, such
as spatial correlations in the statistics of the localization characteristics.
Special attention is paid to the properties of the amorphous solid state in two
spatial dimensions, for which it is shown that Goldstone-type fluctuations
destroy particle localization, the order parameter is driven to zero, and
power-law order-parameter correlations hold.Comment: 20 pages, 3 figure
Photoelectrochemical cells based on inherently conducting polymers
This review of photoelectrochemical cells (PECs) based on inherently conducting polymers (ICPs) deals with the mechanisms of operation and the various factors that influence the overall efficiency of PECs. The factors addressed include ICP composition and oxidation state, the use of nanostructured surfaces and interfaces, and the PEC electrolyte and redox mediator
Zonation of H_(2)O and F Concentrations around Melt Inclusions in Olivines
Studies of both naturally quenched and experimentally reheated melt inclusions have established that they can lose or gain H_(2)O after entrapment in their host mineral, before or during eruption. Here we report nanoSIMS analyses of H2O, Cl and F in olivine around melt inclusions from two natural basaltic samples: one from the Sommata cinder cone on Vulcano Island in the Aeolian arc and the other from the Jorullo cinder cone in the Trans-Mexican Volcanic Belt. Our results constrain olivine/basaltic melt partition coefficients and allow assessment of mechanisms of volatile loss from melt inclusions in natural samples. Cl contents in olivine from both samples are mostly below detection limits (≤0·03 ± 0·01 ppm), with no detectable variation close to the melt inclusions. Assuming a maximum Cl content of 0·03 ppm for all olivines, maximum estimates for Cl partition coefficients between olivine and glass are 0·00002 ± 0·00002. Olivines from the two localities display contrasting H_(2)O and F compositions: Sommata olivines contain 27 ± 11 ppm H_(2)O and 0·28 ± 0·07 ppm F, whereas Jorullo olivines have lower and proportionately more variable H_(2)O and F (11 ± 12 ppm and 0·12 ± 0·09 ppm, respectively; uncertainties are two standard deviations for the entire population). The variations of H_(2)O and F contents in the olivines exhibit clear zonation patterns, increasing with proximity to melt inclusions. This pattern was most probably generated during transfer of volatiles out of the inclusions through the host olivine. H_(2)O concentration gradients surrounding melt inclusions are roughly concentric, but significantly elongated parallel to the crystallographic a-axis of olivine. Because of this preferential crystallographic orientation, this pattern is consistent with H_(2)O loss that is rate-limited by the ‘proton–polaron’ mechanism of H diffusion in olivine. Partition coefficients based on olivine compositions immediately adjacent to melt inclusions are 0·0007 ± 0·0003 for H_(2)O and 0·0005 ± 0·0003 for F. The H_(2)O and F diffusion profiles most probably formed in response to a decrease in the respective fugacities in the external melt, owing to either degassing or mixing with volatile-poor melt. Volatile transport out of inclusions might also have been driven in part by increases in the fugacity within the inclusion owing to post-entrapment crystallization. In the case of F, because of the lack of data on F diffusion in olivine, any interpretation of the measured F gradients is speculative. In the case of H_(2)O, we model the concentration gradients using a numerical model of three-dimensional anisotropic diffusion of H, where initial conditions include both H2O decrease in the external melt and post-entrapment enrichment of H_(2)O in the inclusions. The model confirms that external degassing is the dominant driving force, showing that the orientation of the anisotropy in H diffusion is consistent with the proton–polaron diffusion mechanism in olivine. The model also yields an estimate of the initial H_(2)O content of the Sommata melt inclusions before diffusive loss of 6 wt % H_(2)O. The findings provide new insights on rapid H_(2)O loss during magma ascent and improve our ability to assess the fidelity of the H_(2)O record from melt inclusions
In-situ characterization of Ga2O passivation of In0.53Ga0.47As prior to high-k dielectric atomic layer deposition
Ga2O interfacial passivation layers (IPLs) on In0.53Ga0.47As are investigated using in-situ monochromatic x-ray photoelectron spectroscopy. The oxide is entirely composed of Ga2O when deposited with an effusion cell temperature of 1500 degrees C and substrate temperature of 425 degrees C. The growth on In0.53Ga0.47As reveals slight chemical modification of the surface. The Ga2O behavior and ability to protect the III-V surface are observed following Al2O3 deposition by atomic layer deposition following each precursor pulse. Al2O3 growth by trimethyl-Al (TMA) and water reveals that the IPL undergoes the "clean-up" effect following TMA exposures causing As-As bonding formation resulting in a high interface state density. (C) 2011 American Institute of Physics. (doi:10.1063/1.3615666
Relativistic three-body bound states and the reduction from four to three dimensions
Beginning with an effective field theory based upon meson exchange, the
Bethe-Salpeter equation for the three-particle propagator (six-point function)
is obtained. Using the one-boson-exchange form of the kernel, this equation is
then analyzed using time-ordered perturbation theory, and a three-dimensional
equation for the propagator is developed. The propagator consists of a
pre-factor in which the relative energies are fixed by the initial state of the
particles, an intermediate part in which only global propagation of the
particles occurs, and a post-factor in which relative energies are fixed by the
final state of the particles. The pre- and post-factors are necessary in order
to account for the transition from states where particles are off their mass
shell to states described by the global propagator with all of the particle
energies on shell. The pole structure of the intermediate part of the
propagator is used to determine the equation for the three-body bound state: a
Schr{\"o}dinger-like relativistic equation with a single, global Green's
function. The role of the pre- and post-factors in the relativistic dynamics is
to incorporate the poles of the breakup channels in the initial and final
states. The derivation of this equation by integrating over the relative times
rather than via a constraint on relative momenta allows the inclusion of
retardation and dynamical boost corrections without introducing unphysical
singularities.Comment: REVTeX, 21 pages, 4 figures, epsf.st
Loss of Nmp4 optimizes osteogenic metabolism and secretion to enhance bone quality
A goal of osteoporosis therapy is to restore lost bone with structurally sound tissue. Mice lacking the transcription factor Nuclear Matrix Protein 4 (Nmp4, Zfp384, Ciz, ZNF384) respond to several classes of osteoporosis drugs with enhanced bone formation compared to wild type (WT) animals. Nmp4-/- mesenchymal stem/progenitor cells (MSPCs) exhibit an accelerated and enhanced mineralization during osteoblast differentiation. To address the mechanisms underlying this hyper-anabolic phenotype, we carried out RNA-sequencing and molecular and cellular analyses of WT and Nmp4-/- MSPCs during osteogenesis to define pathways and mechanisms associated with elevated matrix production. We determined that Nmp4 has a broad impact on the transcriptome during osteogenic differentiation, contributing to the expression of over 5,000 genes. Phenotypic anchoring of transcriptional data was performed for the hypothesis-testing arm through analysis of cell metabolism, protein synthesis and secretion, and bone material properties. Mechanistic studies confirmed that Nmp4-/- MSPCs exhibited an enhanced capacity for glycolytic conversion- a key step in bone anabolism. Nmp4-/- cells showed elevated collagen translation and secretion. Expression of matrix genes that contribute to bone material-level mechanical properties were elevated in Nmp4-/- cells, an observation that was supported by biomechanical testing of bone samples from Nmp4-/- and WT mice. We conclude that loss of Nmp4 increases the magnitude of glycolysis upon the metabolic switch, which fuels the conversion of the osteoblast into a super-secretor of matrix resulting in more bone with improvements in intrinsic quality
Correlation Between Trough Plasma Dabigatran Concentrations and Estimates of Glomerular Filtration Rate Based on Creatinine and Cystatin C
AIMS: Dabigatran is largely cleared by renal excretion. Renal function is thus a major determinant of trough dabigatran concentrations, which correlate with the risk of thromboembolic and haemorrhagic outcomes. Current dabigatran dosing guidelines use the Cockcroft–Gault (CG) equation to gauge renal function, instead of contemporary equations including the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations employing creatinine (CKD-EPI_Cr), cystatin C (CKD-EPI_Cys) and both renal biomarkers (CKD-EPI_CrCys). METHODS: A linear regression model including the dabigatran etexilate maintenance dose rate, relevant interacting drugs and genetic polymorphisms (including CES1), was used to analyse the relationship between the values from each renal function equation and trough steady-state plasma dabigatran concentrations. RESULTS: The median dose-corrected trough steady-state plasma dabigatran concentration in 52 patients (38–94 years) taking dabigatran etexilate was 60 µg/L (range 9–279). The dose-corrected trough concentration in a patient on phenytoin and phenobarbitone was >3 standard deviations below the cohort mean. The CG, CKD-EPI_Cr, CKD-EPI_Cys and CKD-EPI_CrCys equations explained (R(2), 95 % CI) 32 % (9–55), 37 % (12–60), 41 % (16–64) and 47 % (20–69) of the variability in dabigatran concentrations between patients, respectively. One-way analysis of variance (ANOVA) comparing the R(2) values for each equation was not statistically significant (p = 0.74). DISCUSSION: Estimates of renal function using the four equations accounted for 32–47 % of the variability in dabigatran concentrations between patients. We are the first to provide evidence that co-administration of phenytoin/phenobarbitone with dabigatran etexilate is associated with significantly reduced dabigatran exposure. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s40268-014-0045-9) contains supplementary material, which is available to authorized users
Case report: Severe mercuric sulphate poisoning treated with 2,3-dimercaptopropane-1-sulphonate and haemodiafiltration
INTRODUCTION: Inorganic mercury poisoning is uncommon, but when it occurs it can result in severe, life-threatening features and acute renal failure. Previous reports on the use of extracorporeal procedures such as haemodialysis and haemoperfusion have shown no significant removal of mercury. We report here the successful use of the chelating agent 2,3-dimercaptopropane-1-sulphonate (DMPS), together with continuous veno-venous haemodiafiltration (CVVHDF), in a patient with severe inorganic mercury poisoning. CASE REPORT: A 40-year-old man presented with haematemesis after ingestion of 1 g mercuric sulphate and rapidly deteriorated in the emergency department, requiring intubation and ventilation. His initial blood mercury was 15 580 μg/l. At 4.5 hours after ingestion he was started on DMPS. He rapidly developed acute renal failure and so he was started on CVVHDF for renal support and in an attempt to improve mercury clearance; CVVHDF was continued for 14 days. METHODS: Regular ultradialysate and pre- and post-filtrate blood samples were taken and in addition all ultradialysate generated was collected to determine its mercury content. RESULTS: The total amount of mercury in the ultrafiltrate was 127 mg (12.7% of the ingested dose). The sieving coefficient ranged from 0.13 at 30-hours to 0.02 at 210-hours after ingestion. He developed no neurological features and was discharged from hospital on day 50. Five months after discharge from hospital he remained asymptomatic, with normal creatinine clearance. DISCUSSION: We describe a patient with severe inorganic mercury poisoning in whom full recovery occurred with the early use of the chelating agent DMPS and CVVHDF. There was removal of a significant amount of mercury by CVVHDF. CONCLUSION: We feel that CVVHDF should be considered in patients with inorganic mercury poisoning, particularly those who develop acute renal failure, together with meticulous supportive care and adequate doses of chelation therapy with DMPS
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