Influence of Shaping Condition on Etherification Performance of Hβ Zeolite

Etherification reaction of FCC light gasoline over Hβ zeolite was investigated to decrease the light olefins in motor gasoline while enhancing octane. Etherification activity of several molecular sieve catalysts for FCC light gasoline was studied in a fixed-bed reactor. The influence of pore-enlarging agent (PEG) with different molecular weight, binder (γ-Al₂O₃), and peptizing agent (HNO₃) in the shaping process on etherification activity of Hβ zeolite was studied. The impregnating ways of precursor of oxides and the order of extruding and impregnating were also investigated. The results show that the activity of extruded Hβ zeolite before impregnating precursor of oxides is higher than the reverse order. The best shaping condition obtained was PEG-4000 10%, γ-Al₂O₃ 20%, and HNO₃ 10%. At the optimal reaction condition, the conversion of tert-olefins reached the peak. 62.93%, the yield of TAME, is also high and the technology can be applied to industry as well.     

航空放射性遥感技术应用研究

航空放射性遥感系统采用航空γ能谱仪,在空中飞行探测地表放射性,能够快速进行大面积环境放射性调查。结合已经开始进行的首次大面积航空放射性遥感调查工作,简要介绍了航空放射性遥感系统构成、核探测γ能谱测量和数据处理技术。对系统转换因子刻度和剥离系数刻度方法进行了讨论,并对初步应用情况进行了总结。     

New approach to enhance adhesions between carbon nanotube emitters and substrate by the combination of electrophoresis and successive electroplating

Complementary electroplating combined with electrophoresis enhanced the field emission characteristics of emitters by improving the adhesions between CNT emitters and substrate. The emitting current of the CNT emitters prepared by our combined method increased nine times higher than that of CNT emitters prepared by electrophoresis only, since electroplating improved the adhesion of CNT emitters. During the life-time measurement for 10 h, the emitting current of CNT emitters fabricated by electrophoresis only was drastically decreased to 13% of the initial current, while that prepared by the combination of electrophoresis and successive electroplating decreased to 64% of the initial current. We suggest that our method is a promising approach for the efficient fabrication of reliable CNT emitters.     

Effects of alloying elements on fracture toughness in the transition temperature region of base metals and simulated heat-affected zones of Mn-Mo-Ni low-alloy steels

This study is concerned with the effects of alloying elements on fracture toughness in the transition temperature region of base metals and heat-affected zones (HAZs) of Mn-Mo-Ni low-alloy steels. Three kinds of steels whose compositions were varied from the composition specification of SA 508 steel (grade 3) were fabricated by vacuum-induction melting and heat treatment, and their fracture toughness was examined using an ASTM E1921 standard test method. In the steels that have decreased C and increased Mo and Ni content, the number of fine M₂C carbides was greatly increased and the number of coarse M₃C carbides was decreased, thereby leading to the simultaneous improvement of tensile properties and fracture toughness. Brittle martensite-austenite (M-A) constituents were also formed in these steels during cooling, but did not deteriorate fracture toughness because they were decomposed to ferrite and fine carbides after tempering. Their simulated HAZs also had sufficient impact toughness after postweld heat treatment. These findings indicated that the reduction in C content to inhibit the formation of coarse cementite and to improve toughness and the increase in Mo and Ni to prevent the reduction in hardenability and to precipitate fine M₂C carbides were useful ways to improve simultaneously the tensile and fracture properties of the HAZs as well as the base metals.     

企业信息化中的网络存储整合应用

首先介绍了网络存储技术中NAS技术和SAN技术的基本原理,并对两者的特性进行了比较;然后详细介绍了企业信息化过程中网络存储整合的一个典型案例,分析了其整合前存在的不足,制定有效的整合实施方案,并对实施过程中许多关键技术部分进行了阐述,最终很好的达到了预定目标;最后总结了网络存储整合需要规划多种技术相融合的必要性.     

Design of the ECRH/ECCD Launcher System for HL-2A Tokamak

An ECRH/ECCD system with two 68GHz/500kW/1S gyrotrons will be built up in HL-2A tokamak. The location of the Gaussian beam waist is 580 mm away from the center of the plasmas and the beam radius is 37 mm at the center of the plasmas. Compared to the minor plasma radius （420 mm）, it is small enough for localized control. The launcher system covers a wide toroidal and poloidal steering range by the two steering plane mirrors. Therefore it is possible to explore the on- and off-axis heating over half of the plasma minor cross section and the co-current drive.     

Reduction of the off-state current of polysilicon thin-filmtransistors by means of a polysilicon buffer layer

The off state current for polysilicon thin-film transistors for pixels in LCDs has been successfully reduced by introducing a polysilicon buffer layer between a polysilicon active layer fabricated by solid-phase-crystallisation (SPC) and a fused quartz substrate. Off-slate current of less than 1 pA under V_gs=-25 V at V_ds=3 V was obtained for n-channel single-gate coplanar transistors using the buffer layer (400 Å)     

化学镀Ni—P镀层的X射线衍射研究

根据X射线衍射分析结果,对化学镀高P(含P>11wt％或19at％)Ni-P镀层加热时效时,镀层成分和加热温度对结构转变的影响作了研究,结果表明,高P共晶、过共晶(含P>11wt％或19at％)合金的结构转变有如下特征:(1)相同加热时效条件下,Ni-P合金的结构转变与成分有密切关系:(2)对同一成分的过共晶合金,Ni-P合金的结构转变与时效温度密切相关;(3)过共晶合金在290～360℃温度范围内时效处理,出现Ni_xP_y介稳相,X射线衍射分析认为Ni_xP_y为Ni_(12)P_5。     

Plasma properties of laser-ablated St target in air

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Can EC-IC bypass prevent brain ischemia from recurring?

The effectiveness of extracranial-intracranial arterial bypass (EC-IC bypass) surgery for patients with hemodynamic compromise still remains controversial. In the present study, we evaluated the correlation between the pre- and post-surgical cerebral hemodynamics and long-term prognosis. 28 patients and a subsequent 21 patients (41 men, eight women: mean age 59.9 [S.D. 8.6] years) with reduced cerebrovascular reserve due to steno-occlusive disease of the cerebral major arteries formed the study groups 1 and 2, respectively. Measurement of the mean hemispheric cerebral blood flow (mCBF) and the cerebral vasoreactivity (%mCVR) with an intravenous acetazolamide injection were performed by a 133Xe inhalation method and SPECT. Patients were treated with EC-IC bypass surgery and measurement of mCBF and %mCVR were made again about one month after surgery. The patients were observed for a long period (mean 44.3 months). During the follow-up period, 6 patients experienced recurrent ischemic strokes. The annual incidence of recurrent ischemic stroke was 4.4%. The patients with significantly reduced pre- and post-surgical resting mCBF of the affected hemisphere were at significantly higher risk of recurrent ischemic stroke than the patients with normal mCBF (p < 0.01). The %mCVR of the affected hemisphere rose after surgery.