Effects of chromium on the temper embrittlement and wear resistance of 0.25% C low-alloy cast steel

The effects of additions of 0.6 to 2.0% Cr on the temper embrittlement behaviour of 0.25 C–1.0 Si–1.3 Mn cast steel under several hardening conditions were studied. The susceptibility to temper embrittlement, transgranular and intergranular fracture were increased as the chromium content increased when the steels were tempered at 350°C and slowly cooled from 550°C. The impact toughness and abrasion resistance of the steels were found to depend to a great extent on the Cr-content and tempering temperature.     

特高压站低压侧保护设备大电流闭锁方案设计

简要介绍了特高压输电系统的基本特征及特高压站低压侧110kV电压等级一次设备的组成。特高压站110kV无功补偿设备采用负荷开关,在短路电流较大时不能直接跳闸,基于此提出了大电流闭锁功能的概念,论述了大电流闭锁功能的主要判据。分别从母线保护、电容器保护、电抗器保护等保护设备角度,提出了在大电流闭锁满足判据的情况下,保护动作后的跳闸出口接点驱动方式。从110kV系统的角度,分析了在母线和无功补偿设备上分别发生故障时的跳闸方式,并讨论了因大电流闭锁动作不能就近跳闸时后备保护逐级隔离故障的实施方案。     

弹药引信封口机滚轮沟槽曲线的分析及优化

阐述了弹药引信包装封口机的卷封机构及二重卷边过程,论述了金属罐二重卷封一道滚轮沟槽曲线的设计,通过有限元仿真模拟卷封过程,分析了滚轮沟槽曲线各段在二重卷边中所起的作用,并对4种曲线进行受力分析比较,确定卷封性能最优良的曲线,并对其进行优化,得到一条理想的曲线。     

微波处理对萌动亚麻籽酚类化合物油相迁移的影响

强化亚麻籽中主要酚类化合物内源性合成和油相迁移对提升亚麻籽油氧化稳定性,最大限度地增加α-亚麻酸生物利用率尤为重要。探究了适度萌动(25℃,24h)联合微波处理(700W,1~5min)对压榨亚麻籽油得率和色泽、脂质构型和结晶熔融性、抗氧化活性和氧化稳定性的影响,并研究了亚麻籽中木酚素和游离酚酸的释放及油相迁移规律。结果表明:单一萌动处理(24h)后亚麻籽油得率降低了7.39%(P<0.05),而进一步微波处理后油脂得率增加了29.31%(P<0.05),这主要归因于微波处理破坏了亚麻籽中油脂体膜结构完整性,导致膜内中性脂质外溢、融合和胞外渗透。微波处理1~5min过程中,亚麻籽油中以LnLnLn构型存在的C18∶3ω3质量分数呈现明显升高趋势,同时总磷脂质量摩尔浓度以及磷脂酰乙醇胺、磷脂酰甘油、磷脂酰肌醇占比显著增加(P<0.05),但未明显影响油脂的结晶行为和熔融特性。与未处理组相比,微波处理5min降低了初级和次级氧化产物水平,显著改善了亚麻籽油的氧化稳定性和抗氧化活性(P<0.05),这主要归因于木酚素大分子及其解聚产物开环异落叶松树脂酚二葡萄糖苷,以及游离酚酸香兰素、香草酸和阿魏酸的油相富集。研究阐释了萌动联合微波预处理对亚麻籽油品质特性的影响,旨在为亚麻籽油提质制取和亚麻籽高值化利用提供理论依据。     

Pulsed Photoacoustic Spectroscopy of I2 and NO2

A novel approach based on the use of ?? = 532?nm pulsed radiation obtained by the second-harmonic generation from the Q-switched Nd: YAG laser and its application for excitation of acoustic modes in a specially designed multi-resonant high-Q factor photoacoustic (PA) cell is reported. The cell is employed for time-domain spectroscopic studies of gaseous NO₂ and I₂ molecules. The time-resolved spectra of NO₂ and I₂ were recorded up to 8000?Hz and 26?000?Hz, respectively. It has been demonstrated for the first time that excited cavity modes which correspond to different transition lines of the I₂ molecules show different behaviors under different pressure and input laser energy. The lowest limit of detection attained with the proposed PA system for NO₂ buffered in realistic air was 14.6?ppbV.     

基于ST损伤向量的心肌缺血罗盘显示

为了将心肌缺血的信息可视化,提出了一种基于ST段损伤向量罗盘显示的心肌缺血检测方法。该方法用ECG设备采集十二导联心电信号,计算各导联的偏移值,用最小二乘解矛盾方程组的方法逆投影到罗盘上,得到ST损伤向量,该向量的大小代表缺血的严重程度,方向指向缺血部位,并用紫色标记。实验对32位心肌缺血患者做检测,将其结果与心电图检测法进行对比,Kappa值为0.903 6,敏感性96.2%,特异性100%,准确性96.9%,阳性率81.3%,P>0.1;对比冠状动脉造影法,Kappa值为0.7949,敏感性96.2%,特异性83.3%,准确性93.8%,阳性率81.2%,P>0.1。数据表明该方法和这两种方法之间都具有很高的一致性,无显著性差异,准确性高,因此ST损伤向量的罗盘显示方法是心肌缺血检测领域一种很有价值的诊断手段。     

Ga1-ＸTiＸSb(Ｘ= 0.25, 0.50, 0.75)电学、磁学及光学性质的第一性原理研究

直接带隙半导体锑化镓（GaSb）凭借其优异的性能在光纤通信、光电器件等领域具有应用价值。为了探索GaSb在光电器件中及新的自旋电子学材料的潜在应用,采用第一性原理计算了不同Ti掺杂浓度的GaSb（Ga1-xTixSb,其中X为Ti原子的掺杂浓度百分比）的电学、磁学及光学性质。计算结果表明：Ga1-xTixSb的能带结构和态密度在费米能级附近产生自旋劈裂并形成净磁矩,使Ga1-xTixSb(X=0.25, 0.50, 0.75)分别表现为半金属铁磁体、稀磁半导体、磁性金属。Ga1-xTixSb优化后晶格常数变大;Ga1-xTixSb的折射率、反射率、吸收系数发生红移且在中远红外波段光吸收系数高于GaSb;Ga1-xTixSb随着Ti掺杂浓度的增加对中远红外波段光子的吸收效果变得更好。计算结果为拓展GaSb基半导体材料在红外探测器、红外半导体激光器等领域的应用以及新的自旋电子学材料的发现提供理论参考。     

FDS-P型绳索取心钻具研制及试验研究

针对复杂地层绳索取心钻进时易出现的内管总成打捞失败问题,开展了FDS-P型绳索取心钻具研制。基于内管总成打捞失败原因分析,完成了FDS-P型绳索取心钻具设计,通过室内试验,初步验证了钻具结构设计的合理性。为进一步验证钻具性能,在贵州页岩气井开展了野外生产试验,先后完成16个回次取心钻进,累计进尺39.03 m,岩心采取率达到98%以上,其中有6个回次发生堵心,内管打捞全部成功,内管到位及堵心均得到了及时提示。实际应用结果表明,FDS-P型绳索取心钻具结构设计合理,具有良好的到位及堵心报信提示作用,内管总成打捞可靠性得到显著提升,有效提高了易堵心地层钻进效率及岩心采取质量。     

基于纳米药物靶向治疗类风湿性关节炎研究

类风湿性关节炎是一种慢性的、以炎性滑膜炎为主的全身性炎症疾病。传统的类风湿性关节炎临床治疗中,由于生物半衰期较短、生物利用度较差,患者需要高剂量和频繁给药,这些药物可能在关节外组织中引起严重的副作用。这些局限性推动了以纳米材料为基础的新型药物递送系统在类风湿性关节炎治疗中的研究和应用。因此,对以纳米材料为基础的药物治疗类风湿性关节炎的最前沿进展进行了总结,并对用于类风湿性关节炎诊断和治疗的各种靶向药物递送系统进行了描述,在此基础上探讨了要解决的关键问题及未来的发展前景。     

Structure and electrical properties of ZnO doped barium-metaphosphate glasses

The zinc–barium–metaphosphate glasses (ZBP) with composition of (50 − x)BaO–xZnO–50P₂O₅; (0 ≤ x ≤ 50 mol %), have been successfully prepared. The influences of the amount of ZnO on the structure, physical and chemical properties, and crystallization behavior of the glasses were investigated using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction and energy dispersive X-ray techniques (XRD/EDX). The density and the glass transition temperature (T_g) of glass were measured using Archimedes' method and differential thermal analysis (DTA). The FTIR analysis revealed a shortening of the phosphate chains by the shift of (P–O–P)_as band to higher wave number owing to the substitution ZnO of BaO. The amount of ZnO was further increased, [ZnO4] tetrahedra were formed and ZnO acted as a glass network former, integrating the phosphate glass network. The density, chemical stability and the activation energy of crystallization of the glasses increased with the amount of ZnO, whereas the glass transition temperature decreased. The dc- and ac-conductivity were measured. The results obtained from ac-conductivity reveals that the values of σ(ω) increases on increasing frequency and it is also increases on increasing the ZnO content level. The dc-conductivity of all the glasses increases with an increase in temperature. The dielectric permittivity (?′) and loss factor (?″) were calculated in the frequency range of 50 Hz–1 MHz. The dipolar relaxation occurred between 10⁵–10⁶ Hz. Finally, the dielectric strength (Δ?) and the relaxation time (τ) were estimated.