7,417 research outputs found
Dynamics of Sclerotium rolfsii as influenced by different crop rhizosphere and microbial community
This study was carried out with the aim of evaluating pathogenicity of Sclerotium rolfsii to different crops influenced by different crop rhizosphere microbes and their population dynamics. Napier was found to be non-preferred host against S. rolfsii pathogen. Among the seven tested crops in micro-plot study, highest level of induction of sclerotial population was observed in groundnut and cow peas (21.81 and 20.06 numbers of sclerotia /100 g of soil, respectively), whereas, reduction in sclerotial number was observed in napier, maize and sorghum plots. S. rolfsii induced damping off was found to be significantly positively correlated with average sclerotial population irrespective of plant cover even at 1% level of significance (r = 0.985) and among the microbiological parameters, FDA was found to be significantly negatively correlated with damping off disease percentage at 5% level of significance (r = - 0.830). Therefore, Napier may be the potential crop to be incorporated in the sequence of rice/vegetable based cropping system in West Bengal for management of this dreaded pathogen
Doping site induced alteration of incommensurate antiferromagnetic ordering in Fe-doped MnNiGe alloys
Electrospun Composite Nanofiltration Membranes for Arsenic Removal
In recent years, significant attention has been paid towards the study and application of mixed matrix nanofibrous membranes for water treatment. The focus of this study is to develop and characterize functional polysulfone (PSf)-based composite nanofiltration (NF) membranes comprising two different oxides, such as graphene oxide (GO) and zinc oxide (ZnO) for arsenic removal from water. PSf/GO- and PSf/ZnO-mixed matrix NF membranes were fabricated using the electrospinning technique, and subsequently examined for their physicochemical properties and evaluated for their performance for arsenite–As(III) and arsenate–As(V) rejection. The effect of GO and ZnO on the morphology, hierarchical structure, and hydrophilicity of fabricated membranes was studied using a scanning electron microscope (SEM), small and ultra-small angle neutron scattering (USANS and SANS), contact angle, zeta potential, and BET (Brunauer, Emmett and Teller) surface area analysis. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to study the elemental compositions and polymer-oxide interaction in the membranes. The incorporation of GO and ZnO in PSf matrix reduced the fiber diameter but increased the porosity, hydrophilicity, and surface negative charge of the membranes. Among five membrane systems, PSf with 1% ZnO has the highest water permeability of 13, 13 and 11 L h-1 m-2 bar-1 for pure water, As(III), and As(V)-contaminated water, respectively. The composite NF membranes of PSf and ZnO exhibited enhanced (more than twice) arsenite removal (at 5 bar pressure) of 71% as compared to pristine PSf membranes, at 43%, whereas both membranes showed only a 27% removal for arsenate.Tawsif Siddique, Rajkamal Balu, Jitendra Mata, Naba K. Dutta, and Namita Roy Choudhur
Interaction-driven giant thermopower in magic-angle twisted bilayer graphene
Magic-angle twisted bilayer graphene has proved to be a fascinating platform to realize and study emergent quantum phases arising from the strong correlations in its flat bands. Thermal transport phenomena, such as thermopower, are sensitive to the particle-hole asymmetry, making them a crucial tool to probe the underlying electronic structure of this material. Here we have carried out thermopower measurements of magic-angle twisted bilayer graphene as a function of carrier density, temperature and magnetic field. We report the observation of an unusually large thermopower reaching a value of the order of 100 mu V K-1 at a low temperature of 1 K. The thermopower exhibits peak-like features that violate the Mott formula in close correspondence to the resistance peaks appearing around the integer filling of the moire bands, including the Dirac point. We show that the large thermopower peaks and their associated behaviour arise from the emergent highly particle-hole-asymmetric electronic structure, due to the sequential filling of the moire flat bands and the associated recovery of Dirac-like physics. Furthermore, the thermopower shows an anomalous peak around the superconducting transition, which points towards the possible role of superconducting fluctuations in magic-angle twisted bilayer graphene. Thermal transport measurements provide a complementary view of the electronic structure of a material to electronic transport. This technique is applied to twisted bilayer graphene, and highlights the particle-hole asymmetry of its band structure
Commensurate anisotropic oscillator, SU(2) coherent states and the classical limit
We demonstrate a formally exact quantum-classical correspondence between the
stationary coherent states associated with the commensurate anisotropic
two-dimensional harmonic oscillator and the classical Lissajous orbits. Our
derivation draws upon earlier work of Louck et al [1973 \textit {J. Math.
Phys.} \textbf {14} 692] wherein they have provided a non-bijective canonical
transformation that maps, within a degenerate eigenspace, the commensurate
anisotropic oscillator on to the isotropic oscillator. This mapping leads, in a
natural manner, to a Schwinger realization of SU(2) in terms of the canonically
transformed creation and annihilation operators. Through the corresponding
coherent states built over a degenerate eigenspace, we directly effect the
classical limit via the expectation values of the underlying generators. Our
work completely accounts for the fact that the SU(2) coherent state in general
corresponds to an ensemble of Lissajous orbits.Comment: 11 pages, Latex2e, iopart.cls, replaced with published versio
Supplementation of a western diet with golden kiwifruits (Actinidia chinensis var.'Hort 16A':) effects on biomarkers of oxidation damage and antioxidant protection
<p>Abstract</p> <p>Background</p> <p>The health positive effects of diets high in fruits and vegetables are generally not replicated in supplementation trials with isolated antioxidants and vitamins, and as a consequence the emphasis of chronic disease prevention has shifted to whole foods and whole food products.</p> <p>Methods</p> <p>We carried out a human intervention trial with the golden kiwifruit, Actinidia chinensis, measuring markers of antioxidant status, DNA stability, plasma lipids, and platelet aggregation. Our hypothesis was that supplementation of a normal diet with kiwifruits would have an effect on biomarkers of oxidative status. Healthy volunteers supplemented a normal diet with either one or two golden kiwifruits per day in a cross-over study lasting 2 × 4 weeks. Plasma levels of vitamin C, and carotenoids, and the ferric reducing activity of plasma (FRAP) were measured. Malondialdehyde was assessed as a biomarker of lipid oxidation. Effects on DNA damage in circulating lymphocytes were estimated using the comet assay with enzyme modification to measure specific lesions; another modification allowed estimation of DNA repair.</p> <p>Results</p> <p>Plasma vitamin C increased after supplementation as did resistance towards H<sub>2</sub>O<sub>2</sub>-induced DNA damage. Purine oxidation in lymphocyte DNA decreased significantly after one kiwifruit per day, pyrimidine oxidation decreased after two fruits per day. Neither DNA base excision nor nucleotide excision repair was influenced by kiwifruit consumption. Malondialdehyde was not affected, but plasma triglycerides decreased. Whole blood platelet aggregation was decreased by kiwifruit supplementation.</p> <p>Conclusion</p> <p>Golden kiwifruit consumption strengthens resistance towards endogenous oxidative damage.</p
KPC-2-producing Klebsiella pneumoniae ST147 in a neonatal unit: Clonal isolates with differences in colistin susceptibility attributed to AcrAB-TolC pump
This study characterizes four KPC-2-producing Klebsiella pneumoniae isolates from neonates belonging to a single sequence type 147 (ST147) in relation to carbapenem resistance and explores probable mechanisms of differential colistin resistance among the clonal cluster.
Whole genome sequencing (WGS) revealed that the isolates were nearly 100% identical and harbored resistance genes (blaKPC-2,OXA-9,CTX-M-15,SHV-11,OXA-1,TEM-1B, oqxA, oqxB, qnrB1, fosA, arr-2, sul1, aacA4, aac(6′)Ib-cr, aac(6′)Ib), and several virulence genes. blaKPC-2 was the only carbapenem-resistant gene found, bracketed between ISKpn7 and ISKpn6 of Tn4401b on a non-conjugative IncFII plasmid. Remarkably, one of the clonal isolates was resistant to colistin, the mechanistic basis of which was not apparent from comparative genomics. The transmissible colistin resistance gene, mcr, was absent. Efflux pump inhibitor, carbonyl cyanide 3-chlorophenylhydrazone (CCCP) rendered a 32-fold decrease in the minimum inhibitory concentration (MIC) of colistin in the resistant isolate only. acrB, tolC, ramA, and soxS genes of the AcrAB-TolC pump system overexpressed exclusively in the colistin-resistant isolate, although the corresponding homologs of the AcrAB-TolC pump, regulators and promoters were mutually identical. No change was observed in the expression of other efflux genes (kpnE/F and kpnG/H) or two-component system (TCS) genes (phoP/phoQ, pmrA/pmrB).
Colistin resistance in one of the clonal KPC-2-producing isolates is postulated to be due to overexpression of the AcrAB-TolC pump. This study is probably the first to report clinical clonal K. pneumoniae isolates with differences in colistin susceptibility. The presence of carbapenem-resistant isolates with differential behavior in the expression of a genomically identical pump system indicates the nuances of the resistance mechanisms and the difficulty of treatment thereof
- …