Determination of Phase Composition of Cobalt Nanoparticles Using 59Co Internal Field Nuclear Magnetic Resonance

It is well known that cobalt exhibits polymorphism, i.e., the co-existence of both the hcp and fcc phases. In particular, the method of synthesis and other thermodynamic conditions is known to play a crucial role in determining the particular phase of cobalt. In this work, we have compared the phase composition of the cobalt nanoparticles synthesized using two different solvents (water) and ethanol (Co@C). XRD measurements confirm the existence of fcc phase in commercial cobalt nanoparticles (Co@A), co-existence of fcc and hcp phases in Co@B, while the existence of the hcp phase in Co@C. We have studied these cobalt nanoparticles using 59Co internal field nuclear magnetic resonance (IFNMR) for verification of phase composition. Our studies reveal that the Co@A has fcc as a major phase with minor quantity hcp phase. Co@B exhibits approximately equal amount of fcc and hcp phase while Co@C exhibits hcp as a major phase with minor fcc phase. Our SEM micrograph studies confirm that the cobalt particles have spherical shape in the fcc phase. The cobalt particles exhibit both spherical and dendrite morphology confirming the co-existence of fcc and hcp phases, while the sample with pure hcp phase exhibits the dendrite morphology. Our studies also throw light on understanding the effect of solvent in the phase formation of the cobalt nanoparticles

Determination of Phase Composition of Cobalt Nanoparticles Using 59Co Internal Field Nuclear Magnetic Resonance

It is well known that cobalt exhibits polymorphism, i.e., the co-existence of both the hcp and fcc phases. In particular, the method of synthesis and other thermodynamic conditions is known to play a crucial role in determining the particular phase of cobalt. In this work, we have compared the phase composition of the cobalt nanoparticles synthesized using two different solvents (water) and ethanol (Co@C). XRD measurements confirm the existence of fcc phase in commercial cobalt nanoparticles (Co@A), co-existence of fcc and hcp phases in Co@B, while the existence of the hcp phase in Co@C. We have studied these cobalt nanoparticles using 59Co internal field nuclear magnetic resonance (IFNMR) for verification of phase composition. Our studies reveal that the Co@A has fcc as a major phase with minor quantity hcp phase. Co@B exhibits approximately equal amount of fcc and hcp phase while Co@C exhibits hcp as a major phase with minor fcc phase. Our SEM micrograph studies confirm that the cobalt particles have spherical shape in the fcc phase. The cobalt particles exhibit both spherical and dendrite morphology confirming the co-existence of fcc and hcp phases, while the sample with pure hcp phase exhibits the dendrite morphology. Our studies also throw light on understanding the effect of solvent in the phase formation of the cobalt nanoparticles

Static and Dynamic Analysis of Spur and Bevel Gear

Gear is the one of the important machine element in the mechanical power transmission system. Spur gear is most basic gear used to transmit power between parallel shafts. Spur gear generally fails by bending failure or contact failure. This paper analyses the bending stresses characteristics of an involute spur gear tooth under static loading conditions. The tooth profile is generated using CATIA and the analysis is carried out by Finite element method using ANSYS software. The stresses at the tooth root are evaluated analytically using existing theoretical models. The theoretical and FEM results are compared. The results obtained theoretically are in good agreement with those obtained from software. Also an attempt is made to introduce Stress and displacement characteristics of tooth under dynamic loading conditions

Abundances of the elements in the solar system

A review of the abundances and condensation temperatures of the elements and their nuclides in the solar nebula and in chondritic meteorites. Abundances of the elements in some neighboring stars are also discussed.Comment: 42 pages, 11 tables, 8 figures, chapter, In Landolt- B\"ornstein, New Series, Vol. VI/4B, Chap. 4.4, J.E. Tr\"umper (ed.), Berlin, Heidelberg, New York: Springer-Verlag, p. 560-63

Isolation and evolutionary analysis of Australasian topotype of bluetongue virus serotype 4 from India

Bluetongue (BT) is a Culicoides-borne disease caused by several serotypes of bluetongue virus (BTV). Similar to other insect-borne viral diseases, distribution of BT is limited to distribution of Culicoides species competent to transmit BTV. In the tropics, vector activity is almost year long, and hence, the disease is endemic, with the circulation of several serotypes of BTV, whereas in temperate areas, seasonal incursions of a limited number of serotypes of BTV from neighbouring tropical areas are observed. Although BTV is endemic in all the three major tropical regions (parts of Africa, America and Asia) of the world, the distribution of serotypes is not alike. Apart from serological diversity, geography-based diversity of BTV genome has been observed, and this is the basis for proposal of topotypes. However, evolution of these topotypes is not well understood. In this study, we report the isolation and characterization of several BTV-4 isolates from India. These isolates are distinct from BTV-4 isolates from other geographical regions. Analysis of available BTV seg-2 sequences indicated that the Australasian BTV-4 diverged from African viruses around 3,500 years ago, whereas the American viruses diverged relatively recently (1,684 CE). Unlike Australasia and America, BTV-4 strains of the Mediterranean area evolved through several independent incursions. We speculate that independent evolution of BTV in different geographical areas over long periods of time might have led to the diversity observed in the current virus population

Cost-Effectiveness of Long-Acting Injectable HIV Preexposure Prophylaxis in the United States: A Cost-Effectiveness Analysis

Background: The HIV Prevention Trials Network (HPTN) 083 trial demonstrated the superiority of long-acting injectable cabotegravir (CAB-LA) compared with oral emtricitabine–tenofovir disoproxil fumarate (F/TDF) for HIV preexposure prophylaxis (PrEP). Objective: To identify the maximum price premium (that is, greatest possible price differential) that society should be willing to accept for the additional benefits of CAB-LA over tenofovir-based PrEP among men who have sex with men and transgender women (MSM/TGW) in the United States. Design: Simulation, cost-effectiveness analysis. Data Sources: Trial and published data, including estimated HIV incidence (5.32, 1.33, and 0.26 per 100 person-years for off PrEP, generic F/TDF and branded emtricitabine–tenofovir alafenamide (F/TAF), and CAB-LA, respectively); 28% 6-year PrEP retention. Annual base-case drug costs: $360 and$16 800 for generic F/TDF and branded F/TAF. Fewer side effects with branded F/TAF versus generic F/TDF were assumed. Target Population: 476 700 MSM/TGW at very high risk for HIV (VHR). Time Horizon: 10 years. Perspective: Health care system. Intervention: CAB-LA versus generic F/TDF or branded F/TAF for HIV PrEP. Outcome Measures: Primary transmissions, quality-adjusted life-years (QALYs), costs (2020 U.S. dollars), incremental cost-effectiveness ratios (ICERs; U.S. dollars per QALY), maximum price premium for CAB-LA versus tenofovir-based PrEP. Results of Base-Case Analysis: Compared with generic F/ TDF (or branded F/TAF), CAB-LA increased life expectancy by 28 000 QALYs (26 000 QALYs) among those at VHR. Branded F/ TAF cost more per QALY gained than generic F/TDF compared with no PrEP. At 10 years, CAB-LA could achieve an ICER of at most $100 000 per QALY compared with generic F/TDF at a maximum price premium of$3700 per year over generic F/TDF (CAB-LA price <$4100 per year). Results of Sensitivity Analysis: In a PrEP-eligible population at high risk for HIV, rather than at VHR (n = 1 906 800; off PrEP incidence: 1.54 per 100 person-years), CAB-LA could achieve an ICER of at most$100 000 per QALY versus generic F/TDF at a maximum price premium of $1100 per year over generic F/TDF (CAB-LA price <$1500 per year). Limitation: Uncertain clinical and economic benefits of averting future transmissions. Conclusion: Effective oral PrEP limits the additional price society should be willing to pay for CAB-LA

Structural and functional insight into the mechanism of an alkaline exonuclease from Laribacter hongkongensis

Alkaline exonuclease and single-strand DNA (ssDNA) annealing proteins (SSAPs) are key components of DNA recombination and repair systems within many prokaryotes, bacteriophages and virus-like genetic elements. The recently sequenced β-proteobacterium Laribacter hongkongensis (strain HLHK9) encodes putative homologs of alkaline exonuclease (LHK-Exo) and SSAP (LHK-Bet) proteins on its 3.17 Mb genome. Here, we report the biophysical, biochemical and structural characterization of recombinant LHK-Exo protein. LHK-Exo digests linear double-stranded DNA molecules from their 5′-termini in a highly processive manner. Exonuclease activities are optimum at pH 8.2 and essentially require Mg2+ or Mn2+ ions. 5′-phosphorylated DNA substrates are preferred over dephosphorylated ones. The crystal structure of LHK-Exo was resolved to 1.9 Å, revealing a ‘doughnut-shaped’ toroidal trimeric arrangement with a central tapered channel, analogous to that of λ-exonuclease (Exo) from bacteriophage-λ. Active sites containing two bound Mg2+ ions on each of the three monomers were located in clefts exposed to this central channel. Crystal structures of LHK-Exo in complex with dAMP and ssDNA were determined to elucidate the structural basis for substrate recognition and binding. Through structure-guided mutational analysis, we discuss the roles played by various active site residues. A conserved two metal ion catalytic mechanism is proposed for this class of alkaline exonucleases

Evaluation of chromatin accessibility in prefrontal cortex of individuals with schizophrenia

Schizophrenia genome-wide association studies have identified >150 regions of the genome associated with disease risk, yet there is little evidence that coding mutations contribute to this disorder. To explore the mechanism of non-coding regulatory elements in schizophrenia, we performed ATAC-seq on adult prefrontal cortex brain samples from 135 individuals with schizophrenia and 137 controls, and identified 118,152 ATAC-seq peaks. These accessible chromatin regions in the brain are highly enriched for schizophrenia SNP heritability. Accessible chromatin regions that overlap evolutionarily conserved regions exhibit an even higher heritability enrichment, indicating that sequence conservation can further refine functional risk variants. We identify few differences in chromatin accessibility between cases and controls, in contrast to thousands of age-related differential accessible chromatin regions. Altogether, we characterize chromatin accessibility in the human prefrontal cortex, the effect of schizophrenia and age on chromatin accessibility, and provide evidence that our dataset will allow for fine mapping of risk variants