Boundary Galerkin Method of a Skew-Derivative Problem in the Exterior of an Open Arc Based on Chebyshev Polynomials

A problem modeling Hall effect in a semiconductor film from an electrode of arbitrary shape is considered, which is a skew-derivative problem. Boundary Galerkin method for solving the problem in Sobolev spaces is developed firstly. The solution is represented in the form of the combined angular potential and single-layer potential. The final integral equations do not contain hypersingular integrals. Uniqueness and existence of the solution to the equations are proved. The weakly singular and Cauchy singular integral arising in these equations can be computed directly by truncated series of Chebyshev polynomials with their weighting function without approximation. The numerical simulation showing the high accuracy of the scheme is presented

Study of a micro chamber quadrupole mass spectrometer

Copyright @ 2008 American Vacuum Society / American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Vacuum Science and Technology Part A: International Journal Devoted to Vacuum, Surfaces, and Films, 26(2), Article number 239 and may be found at http://scitation.aip.org/content/avs/journal/jvsta/26/2/10.1116/1.2827512.The design of a micro chamberquadrupolemass spectrometer (MCQMS) having a small total volume of only 20 cm3, including Faraday cup ion detector and ion source, is described. This MCQMS can resist a vacuum baking temperature of 400–500 °C. The quadrupole elements with a hyperbolic surface are made of a ceramic material and coated with a thin metal layer. The quadrupole mass filter has a field radius of 3 mm and a length of 100 mm. Prototypes of this new MCQMS can detect a minimum partial pressure of 10−8 Pa, have a peak width of ΔM=1 at 10% peak height from mass number 1 to 60, and show an excellent long-term stability. The new MCQMS is intended to be used in residual gas analyses of electron devices during a mutual pumping and baking process.National Key Basic Research Program, the Chinese 111 Project Grant and Program for New Century Excellent Talents in University

λ-Density Functional Valence Bond: A Valence Bond-Based Multiconfigurational Density Functional Theory With a Single Variable Hybrid Parameter

A new valence bond (VB)-based multireference density functional theory (MRDFT) method, named λ-DFVB, is presented in this paper. The method follows the idea of the hybrid multireference density functional method theory proposed by Sharkas et al. (2012). λ-DFVB combines the valence bond self-consistent field (VBSCF) method with Kohn–Sham density functional theory (KS-DFT) by decomposing the electron–electron interactions with a hybrid parameter λ. Different from the Toulouse's scheme, the hybrid parameter λ in λ-DFVB is variable, defined as a function of a multireference character of a molecular system. Furthermore, the EC correlation energy of a leading determinant is introduced to ensure size consistency at the dissociation limit. Satisfactory results of test calculations, including potential energy surfaces, bond dissociation energies, reaction barriers, and singlet–triplet energy gaps, show the potential capability of λ-DFVB for molecular systems with strong correlation

Percutaneous cryoablation of subcapsular hepatocellular carcinoma: a retrospective study of 57 cases

PURPOSEThis study aims to evaluate the safety and effectiveness of the percutaneous cryoablation for subcapsular hepatocellular carcinoma (HCC).METHODSA total of 57 patients with subcapsular (<1 cm form the liver edge) HCCs (68 lesions), who were treated with CT-guided percutaneous cryoablation in the Department of Interventional Radiology of our hospital between July 1, 2016 and September 1, 2018, were retrospectively included. Complete ablation rate, local tumor progression (LTP) and treatment-related complications were evaluated. Furthermore, the degree of intraoperative and postoperative pain was measured with the visual analog scale (VAS), and laboratory findings were compared before and after the procedure.RESULTSAll patients successfully completed the treatment. The mean follow-up period was 12.8 months (range, 3–27 months), and the complete ablation rate was 97% (66/68). Local tumor progression occurred in 11 lesions (16.2%), and the 6-, 12- and 18-month cumulative LTP rates were 4.0%, 8.2% and 20.5%, respectively. Two patients (3.5%, 2/57) developed major complications, and 12 patients had minor complications (22.8%, 12/57). The mean VAS score during the operation was 1.65 points (range, 1–3 points). Postoperative pain worsened in 3 patients, and the VAS scores reached 4–5. Transient changes in biochemical and hematologic markers were observed.CONCLUSIONPercutaneous cryoablation for subcapsular HCC is safe and effective, the procedure is simple and the patients suffer less pain

Drivers of vegetation and soil determine natural regeneration of a single plantation at different slope positions

Promoting natural regeneration in artificial forest ecosystems is crucial for sustainable management. Understanding the fundamental mechanisms and drivers of tree regeneration is the prerequisite for promoting it effectively. This study worked with Larix principis-rupprechtii, a species considered difficult to regenerate. Twenty-four sample plots measuring 30 m × 30 m were established, with eight plots at each of the lower, middle, and upper slope positions, respectively. Field investigation and multivariate analysis were performed to uncover the regeneration traits in the plantations with abundant seedlings on the continuous slope. The results revealed that ground diameter and height of the regeneration (RGD and RH) were larger at the lower slope, with significant positive correlations to available nitrogen (contribution rate, CR: 0.858) and slope (CR: 0.652). In contrast, regeneration density (RD), representing the quantity of regeneration, was greater at the middle slope. Its significant impact factors were slope position (CR: −0.648) and herb diversity, represented by Pielou index (CR: 0.961). Stand density had a significant negative effect on regeneration, particularly at the upper slope, with CRs of −0.842 and −0.764 to RGD/RH and RD, respectively. Common contribution was found among the factors, with the largest contribution groups being the topographical and soil factors (CR: 0.358). These findings provide valuable insights into the single species regeneration progress on northern mountainous slopes and offer essential information for developing facilitation methods for the natural regeneration in artificial forests

[Fe(CN)6] vacancy-boosting oxygen evolution activity of Co-based Prussian blue analogues for hybrid sodium-air battery

Prussian blue analogues (PBAs) have emerged as efficient catalysts for oxygen evolution reaction (OER) due to their porous structure with well-dispersed active sites. However, Co-based PBA (Co-PBA) electrocatalysts are characterized by moderate OER kinetics. In this study, we developed a facile high-yield strategy to fabricate defective Co-PBA (D-Co-PBA) with [Fe(CN)6] vacancies and exposed Co (III) active sites by post-oxidation treatment of the pristine Co-PBA with aqueous H2O2. Rietveld refinement results show that the lattice parameter (a) and unit-cell volume (V) of D-Co-PBA are smaller than those of the pristine Co-PBA, thereby confirming the generation of [Fe(CN)6] vacancies. Density functional theory calculations reveal that the [Fe(CN)6] vacancy can effectively regulate the electronic structure of D-Co-PBA; this condition reduces the reaction barrier of the rate-determining step toward OER. In OER, the D-Co-PBA catalyst achieves a lower overpotential of 400 mV at a current density of 10 mA cm−2, which is superior to that of Ir/C (430 mV) and Co-PBA (450 mV). A hybrid sodium-air battery assembled with Pt/C and D-Co-PBA catalysts displays a discharge voltage of 2.75 V, an ultralow charging–discharging gap of 0.15 V, and a round-trip efficiency of 94.83% on the 1000th cycle at the current density of 0.01 mA cm-2. This study is highly promising for large-scale production of affordable and effective PBA-based materials with desirable OER activity for metal-air batteries and water-alkali electrolyzers, thus helping achieve the goal of sustainability

Whole exome sequencing identifies frequent somatic mutations in cell-cell adhesion genes in chinese patients with lung squamous cell carcinoma

Lung squamous cell carcinoma (SQCC) accounts for about 30% of all lung cancer cases. Understanding of mutational landscape for this subtype of lung cancer in Chinese patients is currently limited. We performed whole exome sequencing in samples from 100 patients with lung SQCCs to search for somatic mutations and the subsequent target capture sequencing in another 98 samples for validation. We identified 20 significantly mutated genes, including TP53, CDH10, NFE2L2 and PTEN. Pathways with frequently mutated genes included those of cell-cell adhesion/Wnt/Hippo in 76%, oxidative stress response in 21%, and phosphatidylinositol-3-OH kinase in 36% of the tested tumor samples. Mutations of Chromatin regulatory factor genes were identified at a lower frequency. In functional assays, we observed that knockdown of CDH10 promoted cell proliferation, soft-agar colony formation, cell migration and cell invasion, and overexpression of CDH10 inhibited cell proliferation. This mutational landscape of lung SQCC in Chinese patients improves our current understanding of lung carcinogenesis, early diagnosis and personalized therapy

Low energy consumption flow capacitive deionization with a combination of redox couples and carbon slurry

Flow-electrode capacitive deionization (FCDI) is a new sustainable desalination technology where continuous desalination can be achieved by the electrodialysis coupling method. However, its development is hindered owing to high energy consumption and low salt removal rate. Herein, by combining ferri-/ferrocyanide redox couple with flow activated carbon (AC)/carbon black (CB) slurry, continuous desalination process is achieved with a high salt removal rate of 1.31 μg cm-2 s-1 and low energy consumption of 102.68 kJ mol-1 at the current density 2.38 mA cm-2 (50 mA current for a 21 cm2 active area). The operating voltage plateau can be reduced to 0.69 V when 10 wt% AC/CB (mass ratio of 9:1) is mixed with 20 mM/20 mM ferri-/ferrocyanide as the flow electrodes, compared with more than 3 V for only carbon flow or redox medium alone. The influences of carbon content and current densities are further investigated to so that the performances can be controlled. This work enables the development of energy-saving desalination systems by coupling FCDI with redox desalination technique