Microstructure and activation characteristics of Mg–Ni alloy modified by multi-walled carbon nanotubes

An Mg–6 wt% Ni alloy was fabricated by a casting technique and the drilled chips ball-milled by high energy ball milling to be examined for their hydrogenation modified with multi-walled carbon nanotubes (MWCNTs). The activation characteristics of ball-milled alloy are compared with those of the materials obtained by ball milling with 5 wt% MWCNTs for 0.5, 1, 2, 5 and 10 h. MWCNTs enhanced the absorption kinetics considerably in all cases. The hydrogen content of the modified powder with MWCNTs reached maximum hydrogen capacity within 2 min of exposure to hydrogen at 370 °C and 2 MPa pressure. X-ray diffraction analysis provided evidence that no carbon-containing phase was formed during milling. However, milling with MWCNTs reduced the crystallite size, even if the milling was carried out for only an hour. The rate-controlling steps of the hydriding reactions at different milling times were determined by fitting the respective kinetic equations. Evidence is provided that nucleation and growth of hydrides are accelerated drastically by a homogenous distribution of MWCNTs on the surface of the ball-milled powders. We show that MWCNTs are very effective at promoting the hydriding/dehydriding kinetics, as well as in increasing the hydrogen capacity of the magnesium alloy.     

双重介质致密砂岩储集层有效性综合评价——以鄂尔多斯盆地西南部红河油田长81油藏为例

鄂尔多斯盆地西南部红河油田延长组长8¹致密砂岩储集层同时发育孔隙型和裂缝型双重储集空间。孔隙型基质储集层具有填隙物成分复杂、岩石粒度细、孔喉结构复杂、物性差和非均质性强等特性,导致有效储集层特征不明确,储集层产量普遍较低;同时,不同产状、张开度和充填程度的裂缝对基质储集层渗透性改造程度不同,井间产能差异较大。基于岩心分析资料,以测试、生产数据为约束条件,综合运用地质研究和测井手段,选取有利测井相、孔喉结构、储集性、渗透性以及裂缝有效性等五项评价指标对长8¹双重介质致密砂岩储集层进行有效性综合评价,并建立了评价标准。对研究区域内31口井的分析表明,储集层有效性评价结果与生产情况有良好一致性。     

Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications

Quantum dots (QDs) interaction with living organisms is of central interest due to their various biological and medical applications. One of the most important mechanisms proposed for various silicon nanoparticle-mediated toxicity is oxidative stress. We investigated the basic processes of cellular damage by oxidative stress and tissue injury following QD accumulation in the gibel carp liver after intraperitoneal injection of a single dose of 2 mg/kg body weight Si/SiO₂ QDs after 1, 3, and 7 days from their administration.QDs gradual accumulation was highlighted by fluorescence microscopy, and subsequent histological changes in the hepatic tissue were noted. After 1 and 3 days, QD-treated fish showed an increased number of macrophage clusters and fibrosis, while hepatocyte basophilia and isolated hepatolytic microlesions were observed only after substantial QDs accumulation in the liver parenchyma, at 7 days after IP injection.Induction of oxidative stress in fish liver was revealed by the formation of malondialdehyde and advanced oxidation protein products, as well as a decrease in protein thiol groups and reduced glutathione levels. The liver enzymatic antioxidant defense was modulated to maintain the redox status in response to the changes initiated by Si/SiO₂ QDs. So, catalase and glutathione peroxidase activities were upregulated starting from the first day after injection, while the activity of superoxide dismutase increased only after 7 days. The oxidative damage that still occurred may impair the activity of more sensitive enzymes. A significant inhibition in glucose-6-phosphate dehydrogenase and glutathione-S-transferase activity was noted, while glutathione reductase remained unaltered.Taking into account that the reduced glutathione level had a deep decline and the level of lipid peroxidation products remained highly increased in the time interval we studied, it appears that the liver antioxidant defense of Carassius gibelio does not counteract the oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner.     

Down-scaling limitations in CMOS devices: Is there a role for the ferroelectrics?

Abstract

This paper reviews down-scaling limitations in CMOS devices, with a special emphasis on the possible application of ferroelectric materials. Ultimate limit in reduction of the thickness of gate oxide is found as the most important limitation. The possibility of replacing or enhancing the gate oxide by a ferroelectric material is critically considered in view of the desired properties of the silicon - to - gate insulator interface.     

测井地震结合储层参数推广反演技术及应用

通过储层测井精细分析评价 ,得到各井准确的储层参数 ,然后 ,利用测井地震资料联合波阻抗宽带约束反演、剖面地震属性提取、多维地震属性约束储层物性反演等技术 ,将地震剖面转换为储层参数剖面 ,最终得到储层厚度、孔隙度、饱和度、H(即有效厚度与孔隙度的乘积 )、HSg(即有效厚度、孔隙度、含气饱和度三者的乘积 )等各种储层参数的平面分布图 ,进而进行储层评价、油藏描述。     

Advances in SiC power MOSFET technology

In recent years, SiC has received increased attention because of its potential for a wide variety of high temperature, high power, high frequency, and/or radiation hardened applications under which conventional semiconductors cannot adequately perform. For semiconductor devices designed to operate in these harsh conditions, SiC offers an unmatched combination of electronic and physical properties. The availability of SiC wafers on a commercial basis has led to the demonstration of many types of metal-oxide semiconductor (MOS)-gated devices that exploit its unique properties. To which extent the potential of SiC power MOSFET can be utilized is a question of appropriate SiC polytype, device structure, MOS interface quality and maturity of the technology. This paper reviews the present status of the SiC power MOSFETs technology that is approaching commercialization. Emphasis is placed upon the impact of SiO₂–SiC interface quality on the performance of SiC MOSFETs.     

Tetanus in Libreville: hospital analysis of 30 cases]

The aim of this study was to compare different muscle contraction types in Parkinson patients and controls. Ten patients with mild to moderate Parkinsonism (7 men, 3 women, mean age 62.3) and 11 controls (7 men, 4 women, mean age 66.0) were investigated. Measurements in eccentric, concentric contraction and stretch-shortening contraction were made using modified Cybex 11 equipment. The torque areas in ankle dorsiflexors at 30 degrees/second, 120 degrees/second and 180 degrees/second were measured. The power (Nm/second) was calculated in a defined range of motion. The power at different angular velocities and contraction types was significantly lower in the patient group than in the control group. In both groups the power in eccentric and stretch-shortening contraction was significantly larger than in concentric contraction. The relative improvement in power in stretch-shortening contraction in patients was equal to the improvement made by the controls. Patients generated significantly more EMG than controls in concentric and eccentric contractions. The EMG in the stretch-shortening cycle was the same in both groups at higher velocities. The patients performed voluntary isolated muscle contraction in the same way as controls, but with a lower efficiency in contraction. The eccentric torque and the supplement of torque generated from the combined eccentric and concentric (stretch-shortening) contraction might be important for achievement of adequate dynamic movements in patients with Parkinson's disease.