Sn(II)-containing phosphates as optoelectronic materials

We theoretically investigate Sn(II) phosphates as optoelectronic materials using first principles calculations. We focus on known prototype materials Sn$_n$P$_2$O$_{5+n}$ (n=2, 3, 4, 5) and a previously unreported compound, SnP$_2$O$_6$ (n=1), which we find using global optimization structure prediction. The electronic structure calculations indicate that these compounds all have large band gaps above 3.2 eV, meaning their transparency to visible light. Several of these compounds show relatively low hole effective masses ($\sim$2-3 m$_0$), comparable the electron masses. This suggests potential bipolar conductivity depending on doping. The dispersive valence band-edges underlying the low hole masses, originate from the anti-bonding hybridization between the Sn 5s orbitals and the phosphate groups. Analysis of structure-property relationships for the metastable structures generated during structure search shows considerable variation in combinations of band gap and carrier effective masses, implying chemical tunability of these properties. The unusual combinations of relatively high band gap, low carrier masses and high chemical stability suggests possible optoelectronic applications of these Sn(II) phosphates, including p-type transparent conductors. Related to this, calculations for doped material indicate low visible light absorption, combined with high plasma frequencies.Comment: 10 pages, 10 figures, Supplementary informatio

Sensitivity Analysis for Coupled Structural-Acoustic System with Absorbing Material Using FEM/BEM

Since the acoustic impedance in water cannot be neglected with respect to the mechanical impedance, the acoustic radiation caused by the vibration of structures in the compressible fluid would react to the structure. Therefore, the fluid-structure interaction needs to be considered. The finite element method is used for structure vibration analysis and the boundary element method for acoustic analysis. Sound absorption materials are used to reduce the scattering sound field in the reference region. The sensitivity analysis of a fully coupled structural-acoustic system is proposed. Numerical tests verify the correctness of the proposed algorithm

Influence of viral hepatitis status on prognosis in patients undergoing hepatic resection for hepatocellular carcinoma: a meta-analysis of observational studies

<p>Abstract</p> <p>Background</p> <p>The influence of viral hepatitis status on prognosis in patients undergoing hepatic resection for hepatocellular carcinoma (HCC) remains a matter of debate. This study is a meta-analysis of the available evidence.</p> <p>Methods</p> <p>A literature search was performed to identify comparative studies reporting postoperative survival of HCC in different types of viral hepatitis. Pooled odds ratios (OR) and weighted mean differences (WMD with 95% confidence intervals (95% CI) were calculated using either the fixed effects model or random effects model.</p> <p>Results</p> <p>Twenty studies matched the selection criteria and reported on 4744 subjects, of whom 2008 in the HBV-positive (B-HCC) group, 2222 in the HCV-positive (C-HCC) group, and 514 in the hepatitis B- and C-negative (NBNC-HCC). Meta-analysis showed that patients with HBV or HCV infection had a worse 5-year disease-free survival when compared to patients with NBNC-HCC (respectively: OR: 0.39, 95% CI: 0.28 to 0.53, P < 0.001; WMD: 0.37, 95% CI: 0.22 to 0.64, P < 0.001). There was a tendency toward higher 5-year overall survival rates in the NBNC-HCC group compared to those in the other two groups, although these differences were not statistically significant. Both the 5-year overall survival and disease-free survival were not different among the B-HCC and C-HCC groups.</p> <p>Conclusions</p> <p>Patients with positive serology for hepatitis B or C undergoing resection for HCC had a poor prognosis compared to patients with negative serology.</p

Festination Correlates with SNCA Polymorphism in Chinese Patients with Parkinson’s Disease

The genetic basis of festination, a common motor symptom in Parkinson’s disease (PD), remains unclear. Since polymorphism in the alpha-synuclein (SNCA) gene is associated with PD phenotype, we examined whether such polymorphism is also associated with festination. SNCA polymorphisms rs11931074 and rs894278 were genotyped in a consecutive series of 258 patients with PD, of whom 122 (47.3%) suffered festination. Univariate analysis revealed significant differences in genotype and minor allele frequencies at rs11931074 or rs894278 between patients with festination and those without it (all p<0.05). Based on logistic regression, a GG or GT genotype at rs11931074 was associated with higher risk of festination among patients with PD (OR 2.077, 95% CI 1.111–3.883, p=0.022), as was the TT genotype at rs894278 (OR 2.271, 95% CI 1.246–4.139, p=0.007). Therefore, we conclude that festination is associated with polymorphism at rs11931074 or rs894278 among patients with PD