367 research outputs found
Probing CP violation with the electric dipole moment of atomic mercury
The electric dipole moment of atomic Hg induced by the nuclear Schiff
moment and tensor-pseudotensor electron-nucleus interactions has been
calculated. For this, we have developed and employed a novel method based on
the relativistic coupled-cluster theory. The results of our theoretical
calculations combined with the latest experimental result of Hg
electric dipole moment, provide new bounds on the T reversal or CP violation
parameters , the tensor-pseudotensor coupling constant
and . This is the most accurate
calculation of these parameters to date. We highlight the the crucial role of
electron correlation effects in their interplay with the P,T violating
interactions. Our results demonstrate substantial changes in the results of
earlier calculations of these parameters which can be attributed to the more
accurate inclusion of important correlation effects in the present work.Comment: 4 pages and 1 figur
Investigation on the Mechanical and Tribological Properties of Aluminium-Tin Based Plain Bearing Material
The purpose of this study is to investigate the Mechanical and Tribological properties of plain bearing alloys used especially in internal combustion engines. The mechanical properties namely Tensile strength and Hardness were investigated according to standard procedure. The sliding friction and wear properties of aluminium-tin alloy against high carbon high chromium steel were investigated at different normal loads as (29.43 N, 33.35 N and 36.25 N). Tests were carried in oil lubricated conditions with a sliding speed of 1 m/s. Prior to experimentation, the circulating engine oil 20w40 was heated to temperature of 800C using heater. The frictional behavior and wear property of aluminium-tin alloy were studied by means of pin-on-disk tribometer. The weight loss of the specimen was measured and wear and friction characteristics were calculated with respect to time, depth of wear track, sliding speed and bearing load. To determine the wear mechanism, the worn surfaces of the samples were examined using Scanning Electron Microscope (SEM). The optimum wear reduction was obtained at different
normal loads and at same sliding speed
Relativistic coupled-cluster calculations of Ne, Ar, Kr and Xe: correlation energies and dipole polarizabilities
We have carried out a detailed and systematic study of the correlation
energies of inert gas atoms Ne, Ar, Kr and Xe using relativistic many-body
perturbation theory and relativistic coupled-cluster theory. In the
relativistic coupled-cluster calculations, we implement perturbative triples
and include these in the correlation energy calculations. We then calculate the
dipole polarizability of the ground states using perturbed coupled-cluster
theory.Comment: 10 figures, 6 tables, submitted to PR
Empirical Geographic Modeling of Switchgrass Yields in the United States
Switchgrass (Panicum virgatum L.) is a perennial grass native to the United States that has been studied as a sustainable source of biomass fuel. Although many fieldāscale studies have examined the potential of this grass as a bioenergy crop, these studies have not been integrated. In this study, we present an empirical model for switchgrass yield and use this model to predict yield for the conterminous United States. We added environmental covariates to assembled yield data from field trials based on geographic location. We developed empirical models based on these data. The resulting empirical models, which account for spatial autocorrelation in the field data, provide the ability to estimate yield from factors associated with climate, soils, and management for both lowland and upland varieties of switchgrass. Yields of both ecotypes showed quadratic responses to temperature, increased with precipitation and minimum winter temperature, and decreased with stand age. Only the upland ecotype showed a positive response to our index of soil wetness and only the lowland ecotype showed a positive response to fertilizer. We view this empirical modeling effort, not as an alternative to mechanistic plantāgrowth modeling, but rather as a first step in the process of functional validation that will compare patterns produced by the models with those found in data. For the upland variety, the correlation between measured yields and yields predicted by empirical models was 0.62 for the training subset and 0.58 for the test subset. For the lowland variety, the correlation was 0.46 for the training subset and 0.19 for the test subset. Because considerable variation in yield remains unexplained, it will be important in the future to characterize spatial and local sources of uncertainty associated with empirical yield estimates
ANTI-INFLAMMATORY AND ANALGESIC ACTIVITY OF ARENGA WIGHTII GRIFF.-AN ENDEMIC PALM OF WESTERN GHATS
Objective: The present study aims to scientifically validate the anti-inflammatory and analgesic activities of Arenga wightii.Methods: The stem pith was excised from mature palm, sliced into small pieces, shade dried and powdered. The powder was extracted with ethanol, concentrated under reduced pressure and the crude extract was referred to as AW. The anti-inflammatory and analgesic activity of AW was analyzed in Wistar rats and Swiss albino mice.Results: The results revealed that the ethanolic extract of the stem pith of A. wightii showed a dose dependent anti-inflammatory and analgesic activity, which was comparable to the standards, indomethacin and acetyl salicylic acid respectively.Conclusion: The results of the current study reveal that A. wightii possesses significant anti-inflammatory and analgesic activity.Ć
Synthesis and characterization of Nano sulphur: Exploring its potential as slow release fertilizer
Sulphur is rapidly being recognized as the fourth key nutrient for plants after nitrogen, phosphorus, and potassium. It functions in several critical metabolic and physiological processes, such as Chlorophyll synthesis, Protein synthesis, Activation of enzymes, Stress tolerance and Seed production. In this background, an attempt was made to synthesize nano sulphur fertilizers for slow release using the reverse microemulsion (water-in-oil microemulsion) technique. Cyclohexane was used as oil phase. Tween-80 and ethanol were used as surfactant and co-surfactant, respectively. Hydrochloric acid and sodium polysulfide solution acted as an aqueous phase. This technique resulted in the successful synthesis of nano sulphur fertilizer. The sulphur nano fertilizer was characterized using X-ray diffraction (XRD), Fourier-Transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) and Thermogravimetric analysis (TGA). The XRD pattern revealed the orthorhombic nature of nano sulphur and the lattice face-centred. The FTIR spectra at 1406 cm-1 confirmed the sulphur vibrations. The microemulsion method yielded stable, uniform, spherical nano sulphur particles with dimensions ranging from 25 to 47 nm. The thermal disintegration between 117Ā°C to 122Ā°C in TGA graph was attributed to the sublimation of sulphur in orthorhombic crystalline form, indicating the successful synthesis of nano sulphur. A laboratory study on nano sulphur fertilizer and conventional sulphur fertilizer was studied with a Percolator reaction system to evaluate the slow release of sulphur from both fertilizers at ambient temperature. Percolation reactor experiment indicated that sulphate release from nano sulphur was longer for 42 days than gypsum amended soil which exhausted within 35 days. Hence, synthesized nano sulphur fertilizer maximizes nutrient retention, eliminates environmental nutrient loses and decreases fertilizer requirements
Time evolution of the Rabi Hamiltonian from the unexcited vacuum
The Rabi Hamiltonian describes a single mode of electromagnetic radiation
interacting with a two-level atom. Using the coupled cluster method, we
investigate the time evolution of this system from an initially empty field
mode and an unexcited atom. We give results for the atomic inversion and field
occupation, and find that the virtual processes cause the field to be squeezed.
No anti-bunching occurs.Comment: 25 pages, 8 figures, RevTe
UāPb zircon-rutile dating of the Llangynog Inlier, Wales: constraints on an Ediacaran shallow marine fossil assemblage from East Avalonia
The Llangynog Inlier of south Wales contains an assemblage of Ediacaran macrofossils from a shallow-marine environment, including discoidal morphs of Aspidella and rare examples of Hiemalora, Palaeopascichnus and Yelovichnus. These are taxa found in other sites in the Avalonian microcontinent (e.g. Charnwood Forest and eastern Newfoundland) and in the younger White Sea Ediacaran assemblages. As the Charnwood fossils reflect a deep-water environment, and no macrofossils have been found in the Ediacaran rocks of the Long Mynd, the fossils of the Llangynog Inlier represent a unique glimpse of shallow marine life in southern Britain (East Avalonia). However, the lack of absolute age constraints has hampered direct comparison with other assemblages. Here, we report in-situ zircon and rutile UāPb dates from a rhyolitic ash-flow layer of the Coed Cochion Volcaniclastic Member, Llangynog Inlier, which constrains the age of the fossiliferous strata. A weighted mean single grain zircon ID-TIMS UāPb age of 564.09 Ā± 0.70 Ma is interpreted as the rhyolite's crystallisation age. This age is consistent with in-situ LA-ICPMS zircon and rutile UāPb dating. The Llangynog age temporally correlates these fossils to dated horizons within East Avalonia at the Beacon Hill Formation, Charnwood (565.22 Ā± 0.89 Ma), and the Stretton Shale Formation, Long Mynd (566.6 Ā± 2.9 Ma). Correlations to West Avalonia include the time-equivalent Fermeuse Formation, St JohnĆ¢ā¬ā¢s Group, eastern Newfoundland (564.13 Ā± 0.65 Ma). The data presented here establish the biota of the Llangynog Inlier as a lateral equivalent to the similarly shallow marine, tidally influenced ecosystem of the upper Fermeuse Formation. Intra-terrane depositional environmental variability also affects what is preserved in Avalonian fossil sites. Further, time-constrained geochemical data reinforce the Llangynog Inlier's classification within the Wrekin Terrane
Plant-Expressed Cocaine Hydrolase Variants of Butyrylcholinesterase Exhibit Altered Allosteric Effects of Cholinesterase Activity and Increased Inhibitor Sensitivity
Butyrylcholinesterase (BChE) is an enzyme with broad substrate and ligand specificities and may function as a generalized bioscavenger by binding and/or hydrolyzing various xenobiotic agents and toxicants, many of which target the central and peripheral nervous systems. Variants of BChE were rationally designed to increase the enzymeās ability to hydrolyze the psychoactive enantiomer of cocaine. These variants were cloned, and then expressed using the magnICON transient expression system in plants and their enzymatic properties were investigated. In particular, we explored the effects that these site-directed mutations have over the enzyme kinetics with various substrates of BChE. We further compared the affinity of various anticholinesterases including organophosphorous nerve agents and pesticides toward these BChE variants relative to the wild type enzyme. In addition to serving as a therapy for cocaine addiction-related diseases, enhanced bioscavenging against other harmful agents could add to the practicality and versatility of the plant-derived recombinant enzyme as a multivalent therapeutic
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