症状性大脑中动脉粥样硬化性狭窄支架植入术后血流动力学研究

【摘要】 目的 探讨症状性大脑中动脉粥样硬化性狭窄患者接受颅内支架植入术前后脑血流动力学变化。方法 回顾成功实施颅内支架植入术的39例症状性大脑中动脉粥样硬化性狭窄患者基线资料,对采用经颅多普勒超声检测术前、术后1周、术后3个月大脑中动脉狭窄段收缩期峰值流速（PSV）和脉动指数（PI）进行分析,比较手术前后病变血管血流动力学变化。结果 39例患者中1例术后狭窄改善不明显,38例动脉平均管径狭窄率由治疗前（80.3±8.5）%改善为术后即刻（16.3±9.2）%（P=0.011）。术后1周、术后3个月大脑中动脉狭窄段PSV与术前比较有明显降低（P=0.023）,PI也较术前明显降低（P=0.028）。术后3个月时2例患者平均PSV回复升高31%～39%;术后3个月与术后1周比较,平均PSV略有升高（P=0.129）,PI稍有增高（P=0.115）,但差异无统计学意义。结论 症状性大脑中动脉粥样硬化性狭窄患者接受颅内支架植入术后短期内脑血流得到有效增加,长期血流改善程度有待观察。

     

Thermovoltaic effect of <Emphasis Type="Italic">p</Emphasis>Si-<Emphasis Type="Italic">n</Emphasis>(Si<Subscript>2</Subscript>)<Subscript>1−x</Subscript>(ZnS)<Subscript>x</Subscript> structures

The pSi-n(Si₂)_1−x (ZnS) _x (0 ≤ x ≤ 0.92) structure, on which thermovoltaic effect is observed, has been obtained by means of liquid-phase epitaxy from tin solution-melt on plates of p-type technical silicon. This effect is explained by grain boundary defects and influence of ZnS impurities in a thin layer adjacent to the p-n-junction.     

The fabrication and investigation of <Emphasis Type="Italic">n</Emphasis>/CdS-<Emphasis Type="Italic">p</Emphasis>/CdTe-<Emphasis Type="Italic">n</Emphasis>/Si structures

Attempts to obtain heterojunctions between A²B⁶ (cadmium telluride and cadmium sulfide) compounds and silicon were made. The distributions of chemical components and some photoelectric properties of the surfaces of the produced layers were investigated.     

Antireflection coatings for solar elements based on Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and SiO<Subscript>2</Subscript> oxides

An alloy of a mixture of Al₂O₃ and SiO₂ oxides has been obtained under radiant heating. It is established that films of the Al₂O₃ and SiO₂ alloy, deposited on the surface of glass and silicon plates, have high mechanical strength and adhesion, are transparent in the SE sensitivity region, and can be used as antireflection coatings.     

Electrochemical oxidation behavior of Mg–Li–Al–Ce–Zn and Mg–Li–Al–Ce–Zn–Mn in sodium chloride solution

Mg–Li–Al–Ce–Zn and Mg–Li–Al–Ce–Zn–Mn alloys were prepared using a vacuum induction melting method. Their electrochemical oxidation behavior in 0.7 M NaCl solution was investigated by means of potentiodynamic polarization, potentiostatic oxidation, electrochemical impedance technique and scanning electron microscopy examination. Their utilization efficiencies and performances as anode of metal–hydrogen peroxide semi-fuel cell were determined. The Mg–Li–Al–Ce–Zn–Mn exhibited higher discharge activity and utilization efficiency than Mg–Li–Al–Ce–Zn, and gave improved fuel cell performance. The utilization efficiency of Mg–Li–Al–Ce–Zn–Mn is comparable with that of the state-of-the-art magnesium alloy anode AP65. The magnesium–hydrogen peroxide semi-fuel cell with Mg–Li–Al–Ce–Zn–Mn anode presented a maximum power density of 91 mW cm⁻² at room temperature. Scanning electron microscopy and electrochemical impedance studies indicated that the alloying element Mn prevented the formation of dense oxide film on the alloy surface and facilitated peeling off of the oxidation products.     

How to make the production of methanol/DME &#8220;GREENER&#8221;&#8212;Integration of wind power with modern coal chemical industry&#8212;

The urgency and necessity of alternative fuels give an impetus to the development of modern coal chemical industry. Coal-based methanol/DME is the key element of this industry. Wind power, whose installed capacity increased at a rate of more than 100% in recent years, has the most developed technologies in renewable energy. However, there still exist many unsolved problems in wind power for on-grid utilization. A new integrated system which combines coal-based methanol/DME production with wind power is proposed in this paper. In this system, wind power is used to electrolyze water to produce H₂ and O₂. The O₂ is fed to the gasifier as gasification agent. The H₂ is mixed with the CO-rich gas to adjust the H₂/CO to an appropriate ratio for methanol synthesis. In comparison with conventional coal-based methanol/DME system, the proposed system omits the expensive and energy-consuming ASU and greatly reduces the water gas shift process, which brings both advantages in the utilization of all raw materials and significant mitigation of CO₂ emission. This system will be attractive in the regions of China which have abundant wind and coal resources.     

A new weighted‐sum‐of‐gray‐gases model for oxy‐combustion scenarios

A new weighted‐sum‐of‐gray gases (WSGG) model that is based on the statistical narrow band model (SNB) RADCAL is proposed for use in computational fluid dynamic (CFD) simulations of air and oxy‐combustion. When employed in conjunction with the discrete ordinates (DO) method, the model predictions compare well against line‐by‐line benchmark data that have been made available recently that are based on the latest spectroscopic databases. Furthermore, the model compares well against the EM2C SNB model calculations that have served as benchmark data in three‐dimensional geometries. Radiative transfer calculations in these prototypical problems therefore confirm recent experimental observations that SNB RADCAL and EM2C SNB serve as good model databases to develop approximate radiative property models. To achieve an optimum balance of speed and accuracy in computationally intensive CFD simulations, non‐gray formulations of the WSGG model are also employed with the P1 model and solutions are compared against those generated by the DO model. While the P1 model gave favorable comparisons when cold, black walls were present, the errors in the surface incident radiative flux predictions increased in the presence of hot, reflecting walls. Finally, in fully coupled simulations of natural gas combustion under air‐firing and oxy‐firing modes, the predicted incident radiative flux profiles were distinctly different between the gray and non‐gray calculations at regions of high temperature gradients, while the centerline temperature predictions were comparatively unaffected. The effects of turbulence radiation interactions were also accounted for through the temperature self‐correlation term. However, the magnitudes of the temperature fluctuations were small and localized within this furnace and did not significantly alter our predictions. Copyright © 2012 John Wiley & Sons, Ltd.     

On the Geometry of Rolling and Interpolation Curves on <Emphasis Type="Italic">S</Emphasis><Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>, SO<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>, and Grassmann Manifolds

We present a procedure to generate smooth interpolating curves on submanifolds, which are given in closed form in terms of the coordinates of the embedding space. In contrast to other existing methods, this approach makes the corresponding algorithm easy to implement. The idea is to project the prescribed data on the manifold onto the affine tangent space at a particular point, solve the interpolation problem on this affine subspace, and then project the resulting curve back on the manifold. One of the novelties of this approach is the use of rolling mappings. The manifold is required to roll on the affine subspace like a rigid body, so that the motion is described by the action of the Euclidean group on the embedding space. The interpolation problem requires a combination of a pullback/push forward with rolling and unrolling. The rolling procedure by itself highlights interesting properties and gives rise to a new, but simple, concept of geometric polynomial curves on manifolds. This paper is an extension of our previous work, where mainly the 2-sphere case was studied in detail. The present paper includes results for the n-sphere, orthogonal group SO _n , and real Grassmann manifolds. In particular, we present the kinematic equations for rolling these manifolds along curves without slip or twist, and derive from them formulas for the parallel transport of vectors along curves on the manifold.      

Graphene‐wrapped poly(2,5‐dihydroxy‐1,4‐benzoquinone‐3,6‐methylene) nanoflowers as low‐cost and high‐performance cathode materials for sodium‐ion batteries

Graphene‐wrapped poly 2,5‐dihydroxy‐1,4‐benzoquinone‐3,6‐methylene (PDBM) nanocomposites with three‐dimensional nanoflower structures have been successfully prepared through the ultrasonic exfoliation and reassembly process in methanol. Compact distribution of graphene into the nanocomposite has established a three‐dimensional conductive network, which contributes to improved properties on discharge capacity and cycle performance. Composite with 20 wt% graphene was proved the best ratio when used in sodium‐ion batteries. Its initial discharge capacity can achieve 210 at 30 mA g^?1. After 100 cycles, the capacity is stable at 121 mAh g^?1. The composite featuring highly conductive channels and multidimensional electron transport pathway is synthesized by an easy ultrasonic way, which may be applied in large scales for sodium‐ion batteries.     

射频消融联合肝动脉化疗栓塞治疗肝癌的应用

Shiquan Shan  Zhijun Zhou  Liping Chen  Zhihua Wang  Kefa Cen 《国际能源研究杂志》2017,41(15):2576-2595

Antireflection coatings for solar photoelectric elements based on SiO<Subscript>2</Subscript> and TiO<Subscript>2</Subscript> mixed oxides

Computer modeling of one-layer antireflection coating based on SiO₂ and TiO₂ mixed oxides was carried out for solar elements. It was concluded that a photoelectric current can be increased by varying the thickness of the covering within the limits of 55–90 nm, while the concentration of SiO₂ in TiO₂ shall not exceed 30%. A method of magnetron spattering was offered as a method for application of the coating based on a SiO₂-TiO₂ mixture.     

Nanocomposite-carbon coated at low-temperature: A new coating material for metallic bipolar plates of polymer electrolyte membrane fuel cells

A nanocomposite-carbon layer is coated onto the surface of 316L stainless steel (SS316) using a beam of accelerated C₆₀ ions at low temperature. The coating is composed of textured graphite nanocrystals ranging in size from 1 to 2 nm, with the graphene plane normal to the coating plane; the nanocrystals are separated by amorphous carbon. This orientation of the graphene layer provides low film resistivity in the direction of the substrate normal. Corrosion resistance tests performed in aggressive anodic and cathodic environments of a polymer electrolyte membrane fuel cell (PEMFC) show that the nanocomposite-carbon coated SS316L exhibits better anticorrosion properties than does bare SS316L. The interfacial contact resistance (ICR) of the nanocomposite-carbon coated SS316L is 12 mΩ cm², which is similar to that of graphite at a compaction force of 150 N cm⁻² and lower than a target of ∼20 mΩ cm². A low value of ICR is maintained even after corrosion tests in aggressive anodic and cathodic environments. The fabricated nanocomposite-carbon coated SS316L exhibits excellent corrosion resistance and low interfacial contact resistance under simulated PEMFC bipolar plate conditions.     

Study on Al<Subscript>2</Subscript>O<Subscript>3</Subscript> extraction from activated coal gangue under different calcination atmospheres

Coal gangue was calcinated under air, nitrogen, carbon dioxide, air–hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650°C. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650°C, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interfacial chemical reaction. The reaction kinetic equation for the leaching process was 1-(1-x)1/3=kt with an apparent activation energy of 48.97 kJ/mol.