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A solution to the problem of Gaussian beam scattering by a circular perfect electric conductor coated with eccentrically anisotropic media is presented. The incident Gaussian beam source is expanded as an approximate expression in the simple form with Taylor's series. The transmitted field in the anisotropically coated region is expressed as an infinite summation of Eigen plane waves with different polar angles. The unknown coefficients of the scattered fields are obtained with the aid of the boundary conditions. The addition theorem for cylindrical functions is applied to transfer from the local coordinates to the global ones. The infinite series can be truncated under the prerequisite of achieving the solution convergence. Only the case of transverse-electric polarization is discussed. The similar formulation of transverse-magnetic polarization can be obtained by adopting a similar method. Some numerical results are presented and discussed. The result is in agreement with that available as expected when the eccentric geometry comes to the concentric one.
Amnestic mild cognitive impairment (aMCI) is characterized by delayed P300 latency and reduced grey matter (GM) volume, respectively. The relationship between the features in aMCI is unclear. This study was to investigate the relationship between the altered P300 latency and the GM volume in aMCI.
Thirty-four aMCI and 34 well-matched normal controls (NC) were studied using electroencephalogram during a visual oddball task and scanned with MRI. Both tests were finished in the same day.
As compared with the NC group, the aMCI group exhibited delayed P300 latency in parietal cortex and reduced GM volumes in bilateral temporal pole and left hippocampus/parahippocampal gyrus. A remarkable negative correlation was found between delayed P300 latency and reduced left hippocampal volume only in the aMCI group. Interestingly, the mediating analysis found P300 latency significantly mediated the association between right supramarginal gyrus volume and information processing speed indicated by Stroop Color and Word Test A scores.
The association between delayed P300 latency and reduced left hippocampal volume in aMCI subjects suggests that reduced left hippocampal volume may be the potential structural basis of delayed P300 latency.
Most of original studies indicated maternal violence experiences is associated with adverse obstetric outcomes, to date, but it is not clear that the association of maternal violence experiences and the risk of postpartum depression (PPD). We aimed to assess the association between maternal violence experiences and risk of developing PPD by performing a meta-analysis of cohort studies.
PubMed, Google Scholar, Cochrane Libraries and Chinese databases were searched through December 2017 to identify studies that assessed the association between violence and PPD. Meta-analysis was conducted by the RevMan software and Stata software. Potential heterogeneity source was explored by subgroup analysis and potential publication bias was assessed by Begg's funnel plots and Egger’s linear regression test.
Overall, women experiencing any violence events compared with the reference group were at a higher risk of developing PPD (odds ratio [OR] = 2.04; 95% confidence interval [CI]: 1.72–2.41). Additionally, different types of violence events such as sexual (OR = 1.56; 95%CI: 1.35–1.81), emotional (OR = 1.75; 95%CI: 1.61–1.89), and physical violence (OR = 1.90; 95%CI: 1.36–2.67), as well as domestic (OR = 2.05; 95%CI: 1.50–2.80) or childhood violence (OR = 1.59; 95%CI: 1.34–1.88) also increased the risk of developing PPD. Relevant heterogeneity moderators have been identified by subgroup analysis. Sensitivity analysis yielded consistent results.
Maternal violence experiences are significantly associated with risk of developing PPD. These finding highlight the necessary to protect women from any types of violence and formulate preventive strategies to promote the maternal mental health.
Graphene oxide (GO) is a promising material in improving the corrosion resistance properties of metals. This improvement significantly relies on the microstructure and electrical properties of GO, which nevertheless is rarely studied. Here, multiscale GOs with different flake sizes and oxidation degrees were fabricated and incorporated into waterborne alkyd resin (AR). The physical and chemical structures of GO and AR/GO composites were characterized in detail. Multiscale GOs are successfully prepared, and the corrosion resistance of AR/GO coatings is measured by electrochemical workstation. Electrochemical experiments indicate that GOs with larger flake sizes have excellent barrier properties due to the shielding effect; GOs with appropriate oxidation degrees could effectively improve the dispersion of GO and avoid the conductive path of GO in the matrix, because oxidation degree of GO could influence the dispersion and electrical properties. The corrosion protection efficiency of AR/GO(GO: 120 μm, 1.5 wt%, sp2/sp3 = 2.61) is 98.14%, which is 2.26 times higher than AR. The multiscale effects of GO on the corrosion resistance property of AR coatings are quite general, thus providing guidelines for developing highly efficient corrosion resistant coatings for practical usage.
Cerebrovascular disease is the most common cause of death in China, and the incidence of ischemic stroke (240 per 100,000 people) is higher than that of hemorrhagic stroke (82 per 100,000 people). More than 80 percent of strokes can be prevented by early control of risk factors. Therefore, identifying and managing high-risk groups is a top priority in preventing stroke. The CHA2DS2-VASc score is a key prediction tool for stratifying stroke risk in individuals with atrial fibrillation (AF) as follows: zero score is low risk; one is intermediate risk; and two is high risk. The present study was undertaken to evaluate the accuracy of the CHA2DS2-VASc scoring system for stratifying ischemic stroke risk in the non-AF population.
We searched PubMed, EMBASE, and the Cochrane Library in June 2018 for relevant diagnostic studies. Study selection, data extraction, and quality assessment (using the QUADAS-2 criteria) were performed independently by two authors. Methodological variation across the selected studies precluded meta-analysis, so the results were synthesized narratively.
Seven prospective studies involving 50,652 patients (6,760 with ischemic stroke) were included. The treatment threshold ranged from two to four across the studies. Three studies reported diagnostic accuracy at a threshold of two, with a sensitivity above 0.8 and a specificity ranging from 0.32 to 0.68. The diagnostic odds ratio was greater than two (seven studies). The two studies using a treatment threshold of four reported a sensitivity of 0.59 to 0.76 and a specificity of 0.43 to 0.69. One study used a threshold of three, with a sensitivity of 0.79 and a specificity of 0.39.
The CHA2DS2-VASc score may be used to predict ischemic stroke in the non-atrial fibrillation population. Treatment thresholds greater than two provide more optimal diagnostic accuracy, although the predictive performance of the CHA2DS2-VASc score may be better in patients with chronic obstructive pulmonary disease but not AF.
The high cohesive interaction between reduced graphene oxide (RGO) sheets usually makes them difficult to disperse, which limits their utilization in achieving effective hybridization with polymers. We report here a new two-step route for preparing non-aggregated and high-conductive RGO powders. Graphene oxide precursor was first reduced by hydrazine hydrate in presence of a thermal unstable surfactant of cetyltrimethylammonium chloride (CTAC). Then a thermal annealing process under H2/Ar atmosphere was further used to remove the non-conductive CTAC molecules. The prepared RGO powder exhibited an electrical conductivity of 2.23 × 104 S m−1 – about ten times higher than the one (N-RGO) simply reduced by hydrazine hydrate. After incorporating into polymethylmethacrylate with a 5 wt% loading, the composite showed a conductivity of 4.11 S m−1, which was 60 times as high as that of the same composite based on N-RGO powder. The addition and subsequent removal of CTAC molecules is an effective method for preparing non-aggregated and highly conductive graphene powder and obtaining good incorporation into polymer matrices.
We report the fabrication of AlGaN/GaN high electron mobility transistors (MIS-HEMTs) with a high breakdown voltage by employing a metal-insulator-semiconductor (MIS) gate structure using Si3N4 insulator. The Si3N4 films were deposited by plasma enhanced chemical vapor deposition (PECVD) as the surface passivation, interlayer films and the gate dielectric. In comparison with Schottky-gate HEMTs, the gate leakage currents of MIS-HEMTs exhibited three orders of magnitude reduction. With similar device structures, the off-state breakdown voltage of MIS-HEMTs was 1050 V with a specific on-resistance of 4.0 mΩ cm2, whereas the breakdown voltage and specific on-resistance of SG-HEMTs were 740 V and 4.4 mΩ cm2, respectively. In addition, the MIS-HEMTs exhibited little current slump in the pulsed measurements and possessed faster switch speed than Si MOSFET. We demonstrate that AlGaN/GaN MIS-HEMTs are promising not only for microwave applications but also for high power switching applications.
Poly(lactic-co-glycolic acid) (PLGA) films with flat surfaces and with 27nm, 190nm, 300nm, 400nm, and 520nm surface features were synthesized using a template method with polydimethylsiloxane (PDMS) molds. The nano patterns were transferred from the self-assembled polystyrene beads to the PLGA films through PDMS molds. After synthesis, the nano patterns were confirmed by AFM height scans. In order to investigate the influence of the materials on bone cells, healthy human osteoblasts were cultured on the PLGA films. The 27nm PLGA surface showed the maximum osteoblast adhesion density and a significant increase compared with the other surface features. For these reasons, and since previous studies have highlighted that similar nanometer surface features on PLGA decreased functions of other cancer cells, this study suggests that PLGA with 27nm surface features should be further studied for bone cancer applications where healthy bone cell functions need to be promoted and cancerous bone cell functions inhibited.
The effects of poly (lactic-co-glycolic acid) (PLGA) surface properties on lung epithelial carcinoma cell functions were previously identified. Results demonstrated decreased lung epithelial carcinoma cell vascular endothelial growth factor (VEGF) synthesis on 23 nm surface featured PLGA compared to the PLGA nano-smooth substrates. To investigate the universality of nanopatterned PLGA on inhibiting cancer cell functions, here, breast epithelial adenocarcinoma cell, MCF-7, early functions were determined on different PLGA nanometer surface topographies. Moreover, the viability of healthy breast cells was determined by an MTT assay to investigate the effects of nanopatterning on healthy breast cell growth. Atomic force microscopy (AFM) verified the varied nanotopographies on the PLGA surfaces prepared in this study. Importantly, results demonstrated significantly decreased breast adenocarcinoma cell functions (including decreased proliferation rate and decreased VEGF synthesis) on 23 nm featured PLGA surfaces compared to the other PLGA surface topographies (specifically, nano-smooth, 300 nm and 400 nm surface featured PLGA surfaces). In contrast, healthy breast epithelial cell studies indicated a 24% higher cell proliferation on the 23 nm featured PLGA surfaces compared to all other PLGA samples. In summary, these results provided further insights into understanding the role surface nanotopographies can have on selectively inhibiting cancer cell functions for a wide range of anti-cancer applications.
This article investigates the effect of grain structure on electromigration (EM) reliability of dual-damascene Cu interconnects with a CoWP capping layer, including the lifetime and statistics. Downstream EM tests were performed on two sets of CoWP-capped Cu interconnects with different grain sizes. Compared to Cu interconnects with the standard SiCN cap layer, the CoWP capping clearly improved the EM lifetime by ∼24× for the small grain structure and by another ∼14× for the large grain structure. Here, the effect of grain structure on EM lifetime was attributed to the grain boundary contribution to mass transport. The lifetime improvement, however, was accompanied with an increase in the statistical deviation, increasing from 0.27 for the SiCN cap to 0.53 for the small grain structure and to 0.88 for the large grain structure with the CoWP cap. This was attributed to the effect of grain structure in changing the statistical distribution of flux divergence sites and thus the failure statistics.
In this work, a visible-light-sensitized neodymium complex with 2-(N,N-diethylanilin-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine (Dpbt) as a synergetic ligand is synthesized and incorporated into poly(methyl methacrylate) (PMMA). Absorption and luminescent spectra of Nd(TTA)3Dpbt (TTA = thenoyltrifluoroacetonate) in PMMA are measured and compared with common complex Nd(TTA)3Phen (Phen = 1,10-phenanthroline). As a result, Nd(TTA)3Dpbt has relatively high luminescent intensity and wide excited spectral range, attributed to the sensitization of the ligand Dpbt. Judd–Ofelt analysis is used, and Judd–Ofelt parameters are calculated (Ω2 = 33.72 × 10−20 cm2, Ω4 = 11.52 × 10−20 cm2, and Ω6 = 6.81 × 10−20 cm2). The radiative properties are predicted and compared with other different Nd complexes. The stimulated emission cross-section of 4F3/2→4I11/2 transition is 3.02 × 10−20 cm2 and the estimated lifetime is 506 μs using the Judd–Ofelt parameters. Experimental fluorescence branching ratio of this transition is quite high for Nd ions. The radiative properties’ investigation for 4F3/2→4I11/2 transition indicates that it is possible to be a laser transition.
PLGA (poly-lactic-co-glycolic acid) has been widely used as a biomaterial in regenerative medicine due to its biocompatibility and biodegradability properties. Previous studies have shown that cells (such as bladder smooth muscle cells, chondrocytes, osteoblasts, and vascular smooth muscle cells) respond differently to nano-structured PLGA surfaces (such as those with surface features less than 100 nm in at least one dimension) compared to nano-smooth surfaces. The purpose of the present in vitro research was to prepare PLGA films with various nanometer surface features and determine, for the first time, whether lung cancer epithelial cells respond differently to such topographies. Poly(dimethylsiloxane) (PDMS) molds prepared by placing PDMS onto various polystyrene monolayers and two solution evaporation methods were used to create nanometer surface features on PLGA. The intended spherical surface nano-topographies on PLGA with RMS values of 2.23, 5.03, 5.42 and 36.90 nm were formed, while PLGA surfaces with RMS values of 0.62 and 2.23 nm were obtained by different solution evaporation methods. Most importantly, lung cancer epithelial cells adhered less on the PLGA surfaces with an RMS value of 0.62, 2.23 and 5.42 nm after 4 hours of culture compared to any other PLGA surface created here. After three days, PLGA surfaces with an RMS value of 0.62 nm had much lower cell density than any other sample. In this manner, PLGA with specific nanometer surface features may inhibit lung cancer cell density which may provide for an important biomaterial for the treatment of lung cancer for a wide range of applications (from drug delivery to regenerative medicine).
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