谱相关技术及其在潜艇结构振动信号传递特性分析中的应用

由于潜艇结构的复杂性,有限元方法和时域相关方法在分析结构振动信号传递特性时精度欠佳。针对上述问题,提出了定量分析结构振动信号传递特性的谱相关技术,该技术通过结构两侧振动信号分析结构对振动信号组成成分的影响,避免了有限元精确建模困难与振动信号通过复杂结构时波形失真较大的难题。将该技术应用于潜艇缩比模型不同结构振动信号传递特性分析中,定量分析结果表明该技术能很好地分析不同结构的振动信号传递特性。     

脲酶抑制剂nBPT对土壤脲酶活性和脲酶产生菌的影响

研究了脲酶抑制剂nBPT对土壤中脲酶活性和细菌、放线菌生长及发酵产酶的影响。结果表明,nBPT用量在0.1%~0.5%之间对土壤脲酶活性影响较小;当浓度达到1%时,抑制作用最为显著。低浓度(0.1 mg/mL)nBPT对细菌、放线菌生长有一定的促进作用;中等浓度和高浓度处理对其生长则表现出抑制作用,且随着nBPT浓度增大而增强。nBPT对细菌、放线菌发酵产酶有明显的抑制作用,最大抑制率分别达55.4%和67.1%。     

一种基于全局信息保持的局部线性嵌入算法及应用

局部线性嵌入（LLE）作为一种经典的流形学习算法，能够得到高维空间的低维流形，但对近邻样本数选择敏感，缺乏全局结构保持能力.为解决此问题，提出了一种改进的LLE算法.在综合考虑样本间差异和数据全局代表性的基础上，通过引入离散度保持项和全局权重指标，提高了算法在降维重构过程中的信息挖掘能力，并降低了对噪声的敏感度，克服了传统LLE算法只关注局部流形特征而忽略全局结构的缺陷.数值仿真和小麦籽粒蛋白质含量软测量的应用仿真验证了该算法的有效性和优越性.     

Revisiting the Chemical Stability of Germanium Selenide (GeSe) and the Origin of its Photocatalytic Efficiency

Recently, germanium selenide (GeSe) has emerged as a promising van der Waals semiconductor for photovoltaics, solar light harvesting, and water photoelectrolysis cells. Contrary to previous reports claiming perfect ambient stability based on experiments with techniques without surface sensitivity, here, by means of surface-science investigations and density functional theory, it is demonstrated that actually both: i) the surface of bulk crystals; and ii) atomically thin flakes of GeSe are prone to oxidation, with the formation of self-assembled germanium-oxide skin with sub-nanometric thickness. Surface oxidation leads to the decrease of the bandgap of stoichiometric GeSe and GeSe_1−x, while bandgap energy increases upon surface oxidation of Ge_1−xSe. Remarkably, the formation of a surface oxide skin on GeSe crystals plays a key role in the physicochemical mechanisms ruling photoelectrocatalysis: the underlying van der Waals semiconductor provides electron–hole pairs, while the germanium-oxide skin formed upon oxidation affords the active sites for catalytic reactions. The self-assembled germanium-oxide/germanium-selenide heterostructure with different bandgaps enables the activation of photocatalytic processes by absorption of light of different wavelengths, with inherently superior activity. Finally, it is discovered that, depending on the specific solvent-GeSe interaction, the liquid phase exfoliation of bulk crystals can induce the formation of Se nanowires.     

外来投资引导下当代俄罗斯建筑创作的多元发展

该文从社会视阈研究当代俄罗斯建筑创作发展,分析在经济转轨时期外来投资的勃兴在城市建设方面引发的变化。并从建筑投资主体的多元化以及建筑创作主体的多元化两个方面阐释当代俄罗斯建筑创作在经济转轨的社会背景下的多元化发展趋向。     

Immobilization of enzyme and antibody on ALD-HfO2-EIS structure by NH3 plasma treatment

Thin hafnium oxide layers deposited by an atomic layer deposition system were investigated as the sensing membrane of the electrolyte-insulator-semiconductor structure. Moreover, a post-remote NH₃ plasma treatment was proposed to replace the complicated silanization procedure for enzyme immobilization. Compared to conventional methods using chemical procedures, remote NH₃ plasma treatment reduces the processing steps and time. The results exhibited that urea and antigen can be successfully detected, which indicated that the immobilization process is correct.     

交联聚乙烯电缆绝缘气体检测系统算法研究与设计

本文基于电化学传感器研制便携式仪器检测交联聚乙烯电力电缆绝缘挥发物中“特征气体”的浓度,并设计气腔以降低气体耗散速度。为了提高检测效率与气体浓度,采用永磁无刷微型泵提高气体流速。考虑仪器便携性,设计滑模控制器转子估计速度,无需速度传感器即可完成速度闭环控制。设计乒乓控制算法降低PWM高频信号对气体传感电路的影响,提高检测系统的信噪比。分别在实验室与测试现场对比速度开环与速度闭环情况下的检测时间与气体浓度,结果表明,相对速度开环控制,速度闭环时仪器的检测时间缩短至少10倍,检测浓度提高20%以上。     

Spontaneous germ cell apoptosis in humans: evidence for ethnic differences in the susceptibility of germ cells to programmed cell death

Since the first clinical studies regarding sealing of arterial puncture sites with collagen with the use of the vascular hemostatic device (VHD) and the hemostatic puncture closing device (HPCD) in the early 1990s were performed, no analysis summarizing the published patients has been reported. Therefore we performed a Medline search of data as far back as 1990 and included abstracts presented at the major scientific meetings in the United States (American Heart Association, American College of Cardiology), Europe (European Society of Cardiology), and Germany (German Society of Cardiology). A total of 6007 patients were found to have been enrolled in studies with VHD (4448 patients) or with HPCD (1559 patients). Parameters analyzed in this review were hemostasis success rates and local complications. To assess the impact of the sealing devices on local complications, studies without control groups were excluded. The hemostasis success rates immediately after deployment seemed to be higher for HPCD, but at 2' to 5' after sheath removal, they were in the same range for VHD and HPCD. In controlled studies minor local complications occurred at a rate of 7.6% in the VHD group and in 6.7% of the HPCD group. Because the control group in the HPCD studies showed a considerably higher rate of minor complications than the VHD group (11.7% vs 5.7%), the reduction in minor complications was statistically significant for HPCD, whereas VHD did not reduce minor local complications. Major local complications were reported in 3.8% of the VHD group but in only 1.8% of the HPCD group. The increase of major local complications was statistically significant with VHD (control, 1.7%) but not with HPCD (control, 1.4%). Our analysis shows that some differences between collagen devices may exist, but neither device has been proven to reduce major local complications.     

Early effects of vasectomy on testicular structure and on germ cell and macrophage apoptosis in the hamster

Some patients with early-stage cirrhosis preserve hepatic function, whereas others have little hepatic reserve and rapidly deteriorate. The aim of this study was to use quantitative tests of liver function (QLFTs) to define the degree of functional hepatic impairment in patients with early-stage cirrhosis (Child-Pugh score 5-7) and to determine whether the tests predicted subsequent hepatic decompensation. We recruited 10 cirrhotic (Cr) patients and 10 healthy controls (NI), who were well matched for race, age, weight, and gender. Clearances of caffeine (CF) and antipyrine (AP) after oral administration were measured from timed samples of saliva. The clearance of cholate (CA) was measured from serum samples obtained after simultaneous oral ([2,2,4,4-2H]CA) and intravenous ([24-13C]CA) administration. CA shunt was calculated as (Cl i.v./Clo x 100%). CF elimination rate (Cr v NI, mean +/- SD: 0.03 +/- 0.02 v 0.075 +/- 0.018 h-1, P < .0005) and AP clearance (24 +/- 16 v 40 +/- 7 mL/minute, P < .02) were reduced in Cr patients. CA shunt was increased in Cr patients (43 +/- 18 v 18 +/- 7%, P < .002). Five Cr patients decompensated during follow-up and had the worst CA shunts (76%, 66%, 51%, 48%, and 45%). Three subsequently received successful orthotopic liver transplantation, 1 died of hepatoma, and 1 is on the waiting list for transplantation. In conclusion, QLFTs define the degree of functional impairment in early cirrhosis and may identify Cr patients at greatest risk of decompensation who may require transplantation for survival.     

AC loss measurements with a cryocooled sample

A new cryostat cooled by a closed-cycle Cryomech GB-37 cryocooler for superconductor measurements at temperatures down to 20 K is described. The sample is conductively coupled to the cold stage so as to minimize vibration and thermal stresses. AC losses have been measured calorimetrically in several high-temperature superconductor coils that have been wound to simulate subscale transformer winding pairs. Stable temperatures down to 20 K were reached on these coils, allowing measurements at practical levels of AC current and I_c. By using short AC current pulses, losses on individual turns could be resolved. Results are reported mainly to showcase the apparatus, measurement procedure, and analytical approach