3,323 research outputs found
Defects induced ferromagnetism in Mn doped ZnO
Single phase Mn doped (2 at %) ZnO samples have been synthesized by
solid-state reaction technique. Before the final sintering at 500 C, the mixed
powders have been milled for different milling periods (6, 24, 48 and 96
hours). The grain sizes of the samples are very close to each other (~ 32 \pm 4
nm). However, the defective state of the samples is different from each other
as manifested from the variation of magnetic properties and electrical
resistivity with milling time. All the samples have been found to be
ferromagnetic with clear hysteresis loops at room temperature. The maximum
value for saturation magnetization (0.11 {\mu}_B / Mn atom) was achieved for 96
hours milled sample. Electrical resistivity has been found to increase with
increasing milling time. The most resistive sample bears the largest saturation
magnetization. Variation of average positron lifetime with milling time bears a
close similarity with that of the saturation magnetization. This indicates the
key role played by open volume vacancy defects, presumably zinc vacancies near
grain surfaces, in inducing ferromagnetic order in Mn doped ZnO. To attain
optimum defect configuration favorable for ferromagnetism in this kind of
samples proper choice of milling period and annealing conditions is required.Comment: Accepted in Journal of Magnetism and Magnetic Material
Genome-wide identification and prediction of SARS-CoV-2 mutations show an abundance of variants: Integrated study of bioinformatics and deep neural learning
Genomic data analysis is a fundamental system for monitoring pathogen evolution and the outbreak of infectious diseases. Based on bioinformatics and deep learning, this study was designed to identify the genomic variability of SARS-CoV-2 worldwide and predict the impending mutation rate. Analysis of 259044 SARS-CoV-2 isolates identified 3334545 mutations with an average of 14.01 mutations per isolate. Globally, single nucleotide polymorphism (SNP) is the most prevalent mutational event. The prevalence of C > T (52.67%) was noticed as a major alteration across the world followed by the G > T (14.59%) and A > G (11.13%). Strains from India showed the highest number of mutations (48) followed by Scotland, USA, Netherlands, Norway, and France having up to 36 mutations. D416G, F106F, P314L, UTR:C241T, L93L, A222V, A199A, V30L, and A220V mutations were found as the most frequent mutations. D1118H, S194L, R262H, M809L, P314L, A8D, S220G, A890D, G1433C, T1456I, R233C, F263S, L111K, A54T, A74V, L183A, A316T, V212F, L46C, V48G, Q57H, W131R, G172V, Q185H, and Y206S missense mutations were found to largely decrease the structural stability of the corresponding proteins. Conversely, D3L, L5F, and S97I were found to largely increase the structural stability of the corresponding proteins. Multi-nucleotide mutations GGG > AAC, CC > TT, TG > CA, and AT > TA have come up in our analysis which are in the top 20 mutational cohort. Future mutation rate analysis predicts a 17%, 7%, and 3% increment of C > T, A > G, and A > T, respectively in the future. Conversely, 7%, 7%, and 6% decrement is estimated for T > C, G > A, and G > T mutations, respectively. T > G\A, C > G\A, and A > T\C are not anticipated in the future. Since SARS-CoV-2 is mutating continuously, our findings will facilitate the tracking of mutations and help to map the progression of the COVID-19 intensity worldwide
A New Integer Linear Programming Formulation to the Inverse QSAR/QSPR for Acyclic Chemical Compounds Using Skeleton Trees
33rd International Conference on Industrial, Engineering and Other Applications of Applied Intelligent Systems, IEA/AIE 2020, Kitakyushu, Japan, September 22-25, 2020.Computer-aided drug design is one of important application areas of intelligent systems. Recently a novel method has been proposed for inverse QSAR/QSPR using both artificial neural networks (ANN) and mixed integer linear programming (MILP), where inverse QSAR/QSPR is a major approach for drug design. This method consists of two phases: In the first phase, a feature function f is defined so that each chemical compound G is converted into a vector f(G) of several descriptors of G, and a prediction function ψ is constructed with an ANN so that ψ(f(G)) takes a value nearly equal to a given chemical property π for many chemical compounds G in a data set. In the second phase, given a target value y∗ of the chemical property π , a chemical structure G∗ is inferred in the following way. An MILP M is formulated so that M admits a feasible solution (x∗, y∗) if and only if there exist vectors x∗, y∗ and a chemical compound G∗ such that ψ(x∗)=y∗ and f(G∗)=x∗. The method has been implemented for inferring acyclic chemical compounds. In this paper, we propose a new MILP for inferring acyclic chemical compounds by introducing a novel concept, skeleton tree, and conducted computational experiments. The results suggest that the proposed method outperforms the existing method when the diameter of graphs is up to around 6 to 8. For an instance for inferring acyclic chemical compounds with 38 non-hydrogen atoms from C, O and S and diameter 6, our method was 5×104 times faster
This is what a MASCOT can do for you - at Apophis
In a similarly brief event some 10½ years before Apophis' fly-by on Friday, April 13th, 2029, the Mobile Asteroid Surface Scout, MASCOT, successfully completed its 17-hours mission on the ~km-sized C-type potentially hazardous asteroid (162173) Ryugu. Investigating the surface and its thermal properties, looking for a magnetic field, and imaging the stark landscapes of this dark rubble pile, it contributed valuable close-up information before the surface sampling by its mothership, HAYABUSA2.
We outline the capabilities of the asteroid nanolanders MASCOT, MASCOT2, and the options for optimized MASCOT@Apophis designs in particular for small spacecraft rendezvous missions to Apophis
Real-Time fMRI Neurofeedback with War Veterans with Chronic PTSD: A Feasibility Study
Many patients with post-traumatic stress disorder (PTSD), especially war veterans, do not respond to available treatments. Here, we describe a novel neurofeedback (NF) intervention using real-time functional magnetic resonance imaging for treating and studying PTSD. The intervention involves training participants to control amygdala activity after exposure to personalized trauma scripts. Three combat veterans with chronic PTSD participated in this feasibility study. All three participants tolerated well the NF training. Moreover, two participants, despite the chronicity of their symptoms, showed clinically meaningful improvements, while one participant showed a smaller symptom reduction. Examination of changes in resting-state functional connectivity patterns revealed a normalization of brain connectivity consistent with clinical improvement. These preliminary results support feasibility of this novel intervention for PTSD and indicate that larger, well-controlled studies of efficacy are warranted
Solving the mu problem with a heavy Higgs boson
We discuss the generation of the mu-term in a class of supersymmetric models
characterized by a low energy effective superpotential containing a term lambda
S H_1 H_2 with a large coupling lambda~2. These models generically predict a
lightest Higgs boson well above the LEP limit of 114 GeV and have been shown to
be compatible with the unification of gauge couplings. Here we discuss a
specific example where the superpotential has no dimensionful parameters and we
point out the relation between the generated mu-term and the mass of the
lightest Higgs boson. We discuss the fine-tuning of the model and we find that
the generation of a phenomenologically viable mu-term fits very well with a
heavy lightest Higgs boson and a low degree of fine-tuning. We discuss
experimental constraints from collider direct searches, precision data, thermal
relic dark matter abundance, and WIMP searches finding that the most natural
region of the parameter space is still allowed by current experiments. We
analyse bounds on the masses of the superpartners coming from Naturalness
arguments and discuss the main signatures of the model for the LHC and future
WIMP searches.Comment: Extended discussion of the LHC phenomenology, as published on JHEP
plus an addendum on the existence of further extremal points of the
potential. 47 pages, 16 figure
Modulatory effects of α- and γ-tocopherols on 4-hydroxyestradiol induced oxidative stresses in MCF-10A breast epithelial cells
The elevated level of circulating estradiol increases the risk of breast tumor development. To gain further insight into mechanisms involved in their actions, we investigated the molecular mechanisms of 4-hydroxyestradiol (4-OHE2) to initiate and/or promote abnormal cell growth, and of α- or γ-tocopherol to inhibit this process. MCF-10A, human breast epithelial cells were incubated with 0.1 µM 4-OHE2, either with or without 30 µM tocopherols for 96 h. 4-OHE2 caused the accumulation of intracellular ROS, while cellular GSH/GSSG ratio and MnSOD protein levels were decreased, indicating that there was an oxidative burden. 4-OHE2 treatment also changed the levels of DNA repair proteins, BRCA1 and PARP-1. γ-Tocopherol suppressed the 4-OHE2-induced increases in ROS, GSH/GSSG ratio, and MnSOD protein expression, while α-tocopherol up-regulated BRCA1 and PARP-1 protein expression. In conclusion, 4-OHE2 increases oxidative stress reducing the level of proteins related to DNA repair. Tocopherols suppressed oxidative stress by scavenging ROS or up-regulating DNA repair elements
Pseudomonas aeruginosa Bacteremia in Children Over Ten Consecutive Years: Analysis of Clinical Characteristics, Risk Factors of Multi-drug Resistance and Clinical Outcomes
This study aimed to evaluate the clinical profiles, antibiotic susceptibility, risk factors of multi-drug resistance (MDR) and outcomes of P. aeruginosa bacteremia in children by retrospective methods at a tertiary teaching children's hospital in Seoul, Korea during 2000-2009. A total of 62 episodes were evaluated and 59 patients (95.2%) had underlying diseases. Multivariate analysis demonstrated that an intensive care unit (ICU) stay within the previous one month was the only independent risk factor for MDR P. aeruginosa bacteremia (odds ratio [OR], 6.8; 95% confidence interval [CI], 1.3-35.8, P = 0.023). The overall fatality rate associated with P. aeruginosa bacteremia was 14.5% (9 of 62). The fatality rate in patients with MDR P. aeruginosa was 57.1%, compared with 9.1% in non-MDR patients (OR 13.3; 95% CI 2.3-77.2, P = 0.006). However, the presence of respiratory difficulty was the only independent risk factor for overall fatality associated with P. aeruginosa bacteremia according to multivariate analysis (OR 51.0; 95% CI 7.0-369.0, P < 0.001). A previous ICU stay and presentation with respiratory difficulty were associated with acquisition of MDR P. aeruginosa and a higher fatality rate, respectively. Future efforts should focus on the prevention and treatment of P. aeruginosa bacteremia in high-risk children
Artificial graphene as a tunable Dirac material
Artificial honeycomb lattices offer a tunable platform to study massless
Dirac quasiparticles and their topological and correlated phases. Here we
review recent progress in the design and fabrication of such synthetic
structures focusing on nanopatterning of two-dimensional electron gases in
semiconductors, molecule-by-molecule assembly by scanning probe methods, and
optical trapping of ultracold atoms in crystals of light. We also discuss
photonic crystals with Dirac cone dispersion and topologically protected edge
states. We emphasize how the interplay between single-particle band structure
engineering and cooperative effects leads to spectacular manifestations in
tunneling and optical spectroscopies.Comment: Review article, 14 pages, 5 figures, 112 Reference
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