129 research outputs found
Microstructure evolution of gas-atomized Feâ6.5 wt% Si droplets
The magnetic Feâ6.5 wt% Si powder was produced by gas atomization and its microstructure was also investigated. The secondary dendritic arm spacing (SDAS) is related to the droplet size, λ = 0.29 · Dâ°Â·â”, and the numerical solidification model was applied to the system, giving rise to the correlation of microstructure to the solidification process of the droplet. It is found that the solid fraction at the end of recalescence is strongly dependent on the undercooling achieved before nucleation; the chances for the smaller droplets to form the grain-refined microstructures are less than the larger ones. Furthermore, the SDAS is strongly influenced by the cooling rate of post-recalescence solidification, and the relationship can be expressed as follows, λ = 74.2 · (T)â»â°Â·ÂłâŽâ·. Then, the growth of the SDAS is driven by the solute diffusion of the interdendritic liquids, leading to a coarsening phenomenon, shown in a cubic root law of local solidification time, λ = 10.73 · (tf)â°Â·ÂČâčâ¶
Blocking interaction between SHP2 and PDâ1 denotes a novel opportunity for developing PDâ1 inhibitors
Small molecular PDâ1 inhibitors are lacking in current immunoâoncology clinic. PDâ1/PDâL1 antibody inhibitors currently approved for clinical usage block interaction between PDâL1 and PDâ1 to enhance cytotoxicity of CD8+ cytotoxic T lymphocyte (CTL). Whether other steps along the PDâ1 signaling pathway can be targeted remains to be determined. Here, we report that methylene blue (MB), an FDAâapproved chemical for treating methemoglobinemia, potently inhibits PDâ1 signaling. MB enhances the cytotoxicity, activation, cell proliferation, and cytokineâsecreting activity of CTL inhibited by PDâ1. Mechanistically, MB blocks interaction between Y248âphosphorylated immunoreceptor tyrosineâbased switch motif (ITSM) of human PDâ1 and SHP2. MB enables activated CTL to shrink PDâL1 expressing tumor allografts and autochthonous lung cancers in a transgenic mouse model. MB also effectively counteracts the PDâ1 signaling on human T cells isolated from peripheral blood of healthy donors. Thus, we identify an FDAâapproved chemical capable of potently inhibiting the function of PDâ1. Equally important, our work sheds light on a novel strategy to develop inhibitors targeting PDâ1 signaling axis
Does Preoperative Radio(chemo)therapy Increase Anastomotic Leakage in Rectal Cancer Surgery? A Meta-Analysis of Randomized Controlled Trials
Objective. Preoperative radio(chemo)therapy (pR(C)T) appears to increase postoperative complications of rectal cancer resection, but clinical trials have reported conflicting results. The objective of this meta-analysis was performed to assess the effects of pR(C)T on anastomotic leak after rectal cancer resection. Methods. PubMed, Embase, and the Cochrane Library were searched from January 1980 to January 2014. Randomized controlled trials included all original articles reporting anastomotic leak in patients with rectal cancer, among whom some received preoperative radiotherapy or chemoradiotherapy while others did not. The analysed end-points were the anastomotic leak. Result. Seven randomized controlled trials with 3375 patients were included in the meta-analysis. 1660 forming the group undergoing preoperative radiotherapy or chemoradiotherapy versus 1715 patients undergoing without preoperative radiotherapy or chemoradiotherapy. The meta-analyses found that pR(C)T was not an independent risk factor for anastomotic leakage (OR 1.02, 95% CI 0.80â1.30; P=0.88). Subgroups analysis was performed and the result was not altered. Conclusions. Current evidence demonstrates that pR(C)T did not increase the risk of postoperative anastomotic leak after rectal cancer resection in patients
Magnetic structures, spin-flop transition and coupling of Eu and Mn magnetism in the Dirac semimetal EuMnBi
We report here a comprehensive study of the AFM structures of the Eu and Mn
magnetic sublattices as well as the interplay between Eu and Mn magnetism in
this compound by using both polarized and non-polarized single-crystal neutron
diffraction. Magnetic susceptibility, specific heat capacity measurements and
the temperature dependence of magnetic diffractions suggest that the AFM
ordering temperature of the Eu and Mn moments is at 22 and 337 K, respectively.
The magnetic moments of both Eu and Mn ions are oriented along the
crystallographic axis, and the respective magnetic propagation vector is
and . With proper neutron
absorption correction, the ordered moments are refined at 3 K as 7.7(1)
and 4.1(1) for the Eu and Mn ions, respectively. In addition, a
spin-flop (SF) phase transition of the Eu moments in an applied magnetic field
along the axis was confirmed to take place at a critical field of B
5.3 T. The evolution of the Eu magnetic moment direction as a function
of the applied magnetic field in the SF phase was also determined. Clear kinks
in both field and temperature dependence of the magnetic reflections (,
0, 1) of Mn were observed at the onset of the SF phase transition and the AFM
order of the Eu moments, respectively. This unambiguously indicates the
existence of a strong coupling between Eu and Mn magnetism. The interplay
between two magnetic sublattices could bring new possibilities to tune Dirac
fermions via changing magnetic structures by applied fields in this class of
magnetic topological semimetals.Comment: 15 pages, 12 figures, accepted by Physical Review Researc
Multispectral Palmprint Recognition Using a Quaternion Matrix
Palmprints have been widely studied for biometric recognition for many years. Traditionally, a white light source is used for illumination. Recently, multispectral imaging has drawn attention because of its high recognition accuracy. Multispectral palmprint systems can provide more discriminant information under different illuminations in a short time, thus they can achieve better recognition accuracy. Previously, multispectral palmprint images were taken as a kind of multi-modal biometrics, and the fusion scheme on the image level or matching score level was used. However, some spectral information will be lost during image level or matching score level fusion. In this study, we propose a new method for multispectral images based on a quaternion model which could fully utilize the multispectral information. Firstly, multispectral palmprint images captured under red, green, blue and near-infrared (NIR) illuminations were represented by a quaternion matrix, then principal component analysis (PCA) and discrete wavelet transform (DWT) were applied respectively on the matrix to extract palmprint features. After that, Euclidean distance was used to measure the dissimilarity between different features. Finally, the sum of two distances and the nearest neighborhood classifier were employed for recognition decision. Experimental results showed that using the quaternion matrix can achieve a higher recognition rate. Given 3000 test samples from 500 palms, the recognition rate can be as high as 98.83%
A Method for Generation Phage Cocktail with Great Therapeutic Potential
Background: Bacteriophage could be an alternative to conventional antibiotic therapy against multidrug-resistant bacteria. However, the emergence of resistant variants after phage treatment limited its therapeutic application. Methodology/Principal Findings: In this study, an approach, named ââStep-by-Stepâ â (SBS), has been established. This method takes advantage of the occurrence of phage-resistant bacteria variants and ensures that phages lytic for wild-type strain and its phage-resistant variants are selected. A phage cocktail lytic for Klebsiella pneumoniae was established by the SBS method. This phage cocktail consisted of three phages (GH-K1, GH-K2 and GH-K3) which have different but overlapping host strains. Several phage-resistant variants of Klebsiella pneumoniae were isolated after different phages treatments. The virulence of these variants was much weaker [minimal lethal doses (MLD).1.3610 9 cfu/mouse] than that of wild-type K7 countpart (MLD = 2.5610 3 cfu/mouse). Compared with any single phage, the phage cocktail significantly reduced the mutation frequency of Klebsiella pneumoniae and effectively rescued Klebsiella pneumoniae bacteremia in a murine K7 strain challenge model. The minimal protective dose (MPD) of the phage cocktail which was sufficient to protect bacteremic mice from lethal K7 infection was only 3.0610 4 pfu, significantly smaller (p,0.01) than that of single monophage. Moreover, a delayed administration of this phage cocktail was still effective in protection against K7 challenge. Conclusions/Significance: Our data showed that the phage cocktail was more effective in reducing bacterial mutatio
Ca2+-dependent NOX5 (NADPH oxidase 5) exaggerates cardiac hypertrophy through reactive oxygen species production
NOX5 (NADPH oxidase 5) is a homolog of the gp91phox subunit of the phagocyte NOX, which generates reactive oxygen species. NOX5 is involved in sperm motility and vascular contraction and has been implicated in diabetic nephropathy, atherosclerosis, and stroke. The function of NOX5 in the cardiac hypertrophy is unknown. Because NOX5 is a Ca2+-sensitive, procontractile NOX isoform, we questioned whether it plays a role in cardiac hypertrophy. Studies were performed in (1) cardiac tissue from patients undergoing heart transplant for cardiomyopathy and heart failure, (2) NOX5-expressing rat cardiomyocytes, and (3) mice expressing human NOX5 in a cardiomyocyte-specific manner. Cardiac hypertrophy was induced in mice by transverse aorta coarctation and Ang II (angiotensin II) infusion. NOX5 expression was increased in human failing hearts. Rat cardiomyocytes infected with adenoviral vector encoding human NOX5 cDNA exhibited elevated reactive oxygen species levels with significant enlargement and associated increased expression of ANP (atrial natriuretic peptides) and ÎČ-MHC (ÎČ-myosin heavy chain) and prohypertrophic genes (Nppa, Nppb, and Myh7) under Ang II stimulation. These effects were reduced by N-acetylcysteine and diltiazem. Pressure overload and Ang II infusion induced left ventricular hypertrophy, interstitial fibrosis, and contractile dysfunction, responses that were exaggerated in cardiac-specific NOX5 trangenic mice. These phenomena were associated with increased reactive oxygen species levels and activation of redox-sensitive MAPK (mitogen-activated protein kinase). N-acetylcysteine treatment reduced cardiac oxidative stress and attenuated cardiac hypertrophy in NOX5 trangenic. Our study defines Ca2+-regulated NOX5 as an important NOX isoform involved in oxidative stress- and MAPK-mediated cardiac hypertrophy and contractile dysfunction
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