303 research outputs found
Prediction of interesting ferromagnetism in Janus semiconducting CrAsP monolayer
Two-dimensional (2D) half-metallic materials that have sparked intense
interest in advanced spintronic applications are essential to the developing
next-generation nanospintronic devices. Here we have adopted a first-principles
calculation method to predict the magnetic properties of intrinsic, Se-doped,
and biaxial strain tuning CrAsP monolayer. The Janus CrAsP monolayer is
proved to be an intrinsic ferromagnetic (FM) semiconductor with a exchange
splitting bandgap of 0.15 eV at the PBE+U level. Concentration-dependent Se
doping such as CrAsSeP (x = 0.25, 0.50, 0.75) can regulate
CrAsP from FM semiconductor to FM half-metallicity. Specifically, the
spin-up channel crosses the Fermi level, while the spin-down channel has a
bandgap. More interestingly, the wide half-metallic bandgaps and spin bandgaps
make them have important implications for the preparation of spintronic
devices. At last, we also explore the effect of biaxial strain from -14% to 10%
on the magnetism of the CrAsP monolayer. There appears a transition from FM
to antiferromagnetic (AFM) at a compressive strain of -10.7%, originating from
the competition between the indirect FM superexchange interaction and the
direct AFM interaction between the nearest-neighbor Cr atoms. Additionally,
when the compressive strain to -2% or the tensile strain to 6%, the
semiconducting CrAsP becomes a half-metallic material. These charming
properties render the Janus CrAsP monolayer with great potential for
applications in spintronic devices.Comment: 14 pages, 4 figure
First-principles calculations on the mechanical, electronic, magnetic and optical properties of two-dimensional Janus CrTeX (X= P, As, Sb) monolayers
Janus materials possess extraordinary physical, chemical, and mechanical
properties caused by symmetry breaking. Here, the mechanic properties,
electronic structure, magnetic properties, and optical properties of Janus
CrTeX (X= P, As, Sb) monolayers are systematically investigated by the
density functional theory. Janus CrTeP, CrTeAs, and CrTeSb are
intrinsic ferromagnetic (FM) half-metals with wide spin gaps and half-metallic
gaps. Monte Carlo simulations based on the Heisenberg model estimate the Curie
temperature (\emph{T}) of these monolayers are about 583, 608, and 597 K,
respectively. Additionally, it is found that CrTeX (X= P, As, Sb)
monolayers still exhibit FM half-metallic properties under biaxial strain from
-6% to 6%. At last, the CrTeP monolayer has a higher absorption coefficient
than the CrTeAs and CrTeSb monolayers in the visible region. The
results predict that Janus CrTeX (X= P, As, Sb) monolayers with novel
properties have good potential for applications in future nanodevices.Comment: 14 pages, 5 figure
Identification and control of a Pseudomonas spp (P. fulva and P. putida) bloodstream infection outbreak in a teaching hospital in Beijing, China
SummaryObjectivesAn outbreak of bacteremia caused by Pseudomonas spp (P. fulva and P. putida) was first identified in our hospital in the summer of 2010 and reoccurred in the following year. Based on the epidemiological data collected in these 2 years, we initiated an investigation on the source of the outbreak. The aim of this study was to report the results of the investigation, as well as the intervention strategies that resulted in successful control of the outbreak.MethodsAn infection control team was set up consisting of infectious disease specialists, microbiologists, infection control practitioners, and head nurses. The microbiology and medical records of case-patients with P. fulva or P. putida bloodstream infections were reviewed. Environmental samples and intravenous (IV) solutions from the wards and the pharmacy center were collected for culturing. The molecular characteristics of the bacterial isolates were studied by pulsed-field gel electrophoresis (PFGE). Strict infection control strategies were implemented.ResultsA total of 20 case-patients from five inpatient wards were identified during three summer seasons from 2010 to 2012. Nineteen of them recovered with proper antibiotics. Unfortunately one died from complications of heart failure. A total of 19 isolates of P. fulva and four of P. putida were identified, of which 20 were from blood, two from environmental surface samples from the hospital pharmacy, and one from an in-use compounded solution from a case-patient in the cardiology ward. Molecular analysis revealed that the P. fulva isolated from the in-use compounded solution (5% glucose solution containing insulin, isosorbide dinitrate, and potassium magnesium aspartate) and the environmental samples had the same PFGE type as the clinical isolates.ConclusionsThe investigation identified that contaminated IV solution was the source of the P. fulva bacteremia, which prompted us to implement intensified control measures that resulted in successful control of the outbreak
Mechanical deformation mechanism and verification of sections at junctions of light and dark tunnel in a mountain area
Projects involving junctions of light and dark tunnel in mountainous areas are complex engineering problems that combine tunnel structure, slope rock-soil mass and protection projects. Such junctions suffer from a complex and changeable load. The stress and deformation of the junction varies under different conditions. Thus, it is a major source of inconvenience for construction and monitoring operations. In this paper, according to the load conditions at a junction of light and dark tunnel, we divide the junction hole into thrust, compression, and combined thrust-compression types. Three types of structures were simulated by numerical analysis, and we explored the structural deformation and stress of these types of tunnel under different condition. Thus, in any construction process, the mechanical deformation mechanism and the weak point in the structure should be worked out. Based on the weak parts, some monitoring points were installed, and four fields for monitoring were chosen. The monitoring results show that the actual deformation, stress and structural failure location are basically consistent with the numerical simulation results. The deformation mechanism of light and dark tunnel junction obtained can provide the basis for selecting the treatment measures and controlling the structural deformation. Furthermore, the results can also be used as a reference for similar engineering design, construction and site monitoring projects
Effective Image Restorations Using a Novel Spatial Adaptive Prior
Bayesian or Maximum a posteriori (MAP) approaches can effectively overcome the ill-posed problems of image restoration or deconvolution through incorporating a priori image information. Many restoration methods, such as nonquadratic prior Bayesian restoration and total variation regularization, have been proposed with edge-preserving and noise-removing properties. However, these methods are often inefficient in restoring continuous variation region and suppressing block artifacts. To handle this, this paper proposes a Bayesian restoration approach with a novel spatial adaptive (SA) prior. Through selectively and adaptively incorporating the nonlocal image information into the SA prior model, the proposed method effectively suppress the negative disturbance from irrelevant neighbor pixels, and utilizes the positive regularization from the relevant ones. A two-step restoration algorithm for the proposed approach is also given. Comparative experimentation and analysis demonstrate that, bearing high-quality edge-preserving and noise-removing properties, the proposed restoration also has good deblocking property
Using Peer Comparison Approaches to Measure Software Stability
Software systems must change to adapt to new functional requirements and new nonfunctional requirements. This is called software revision. However, not all the modules within the system need to be changed during each revision. In this paper, we study how frequently each module is modified. Our study is performed through comparing the stability of peer software modules. The study is performed on six open-source Java projects: Ant, Flow4j, Jena, Lucence, Struct, and Xalan, in which classes are identified as basic software modules. Our study shows (1) about half of the total classes never changed; (2) frequent changes occur to small number of classes; and (3) the number of changed classes between current release and next release has no significant relations with the time duration between current release and next release. Keywords: software evolution; software revision; software stability; class stability; open-source project; Java clas
Cardioprotective effects of tanshinone IIA pretreatment via kinin B2 receptor-Akt-GSK-3β dependent pathway in experimental diabetic cardiomyopathy
<p>Abstract</p> <p>Aims</p> <p>Diabetic cardiomyopathy, characterized by myocardial structural and functional changes, is a specific cardiomyopathy develops in patients with diabetes mellitus. The present study was to investigate the role of kinin B2 receptor-Akt-glycogen synthase kinase (GSK)-3β signalling pathway in mediating the protective effects of tanshinone IIA (TSN) on diabetic cardiomyopathy.</p> <p>Methods and results</p> <p>Streptozocin (STZ) induced diabetic rats (n = 60) were randomized to receive TSN, TSN plus HOE140 (a kinin B2 receptor antagonist), or saline. Healthy Sprague-Dawley (SD) rats (n = 20) were used as control. Left ventricular function, myocardial apoptosis, myocardial ultrastructure, Akt, GSK-3β and NF-κB phosphorylation, the expression of TNF-α, IL-6 and myeloperoxidase (MPO) were examined. Cardiac function was well preserved as evidenced by increased left ventricular ejection fraction (LVEF) and ± dp/dt (maximum speed of contraction/relaxation), along with decreased myocardial apoptotic death after TSN administration. TSN pretreatment alleviated mitochondria ultrastructure changes. TSN also enhanced Akt and GSK-3β phosphorylation and inhibited NF-κB phosphorylation, resulting in decreased TNF-α, IL-6 and MPO activities. Moreover, pretreatment with HOE140 abolished the beneficial effects of TSN: a decrease in LVEF and ± dp/dt, an inhibition of cardiomyocyte apoptosis, a destruction of cardiomyocyte mitochondria cristae, a reduction of Akt and GSK-3β phosphorylation, an enhancement of NF-κB phosphorylation and an increase of TNF-α, IL-6 and MPO production.</p> <p>Conclusion</p> <p>These data indicated that TSN is cardioprotective in the context of diabetic cardiomyopathy through kinin B2 receptor-Akt-GSK-3β dependent pathway.</p
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