热轧卷取温度对HC340LAD+Z带钢力学性能的影响

为了研究热轧卷取温度对热镀锌HC340LAD+Z带钢力学性能的影响规律,对同一炉次、相同规格的3批次钢坯,分别采用580、620、660 ℃3个卷取温度,以及相同的冷轧、热镀锌、退火工艺进行了试验研究。结果表明,随着卷取温度的升高,成品带钢的屈服强度、抗拉强度降低,伸长率稍有增加,均满足EN10346标准对HC340LAD+Z带钢力学性能的要求。热轧卷取温度为620 ℃时,HC340LAD+Z带钢的屈服强度为389.2 MPa,抗拉强度为474.3 MPa,伸长率A80为26.5%,其综合力学性能对比标准指标,富裕量最佳。     

A new arrangement of Z‐source AC–AC converter and its closed‐loop control system

In this study, a Z‐source alternating current‐to‐alternating current (AC–AC) converter with a specific topology, which can provide both buck and boost modes, is investigated. This converter, which can be implemented easily, utilizes only two switches with complemented commands. A comparison between the Z‐source AC–AC converter and a conventional thyristor voltage controlled one is presented here, and it shows that in the most areas, the Z‐source converter provides a faster response and lower total harmonic distortion of the output currents than the conventional one. Moreover, the Z‐source converter is also extended to the multiphase systems. In addition, a new arrangement of this converter is proposed here to remove the isolated single‐phase sources. Furthermore, an open‐loop method is proposed for soft‐starting applications. Finally, a closed‐loop control system is also suggested for a three‐phase Z‐source converter to soft start and control the speed of an induction motor. Computer simulations show the validity and effectiveness of the proposed schemes. Copyright © 2014 John Wiley & Sons, Ltd.     

激光修补技术在修复薄膜图形缺陷上的应用——薄膜图形缺陷激光修补机

阐述了应用激光修补技术在玻璃基板上去除金属及其化合物薄膜和在玻璃基板上沉积金属薄膜的图形缺陷修补原理与方法;简述了影响薄膜图形缺陷修补质量与效率的关键技术;简单介绍了薄膜图形缺陷激光修补机的系统构成及其技术与性能指标.     

13-Hydroxy-9Z,15Z-Octadecadienoic Acid Production by Recombinant Cells Expressing Lactobacillus acidophilus 13-Hydratase

Recombinant Escherichia coli cells expressing linoleate 13‐hydratase from Lactobacillus acidophilus were permeabilized by treating with 0.2 M NaCl. The optimal conditions for the production of 13‐hydroxy‐9,15(Z,Z)‐octadecadienoic acid (13‐HODE) from α‐linolenic acid by permeabilized recombinant cells were pH 6.0, 40 °C, 7.5 % (v/v) methanol, 60 g/l permeabilized cells, and 15 g/l α‐linolenic acid. Under these conditions, permeabilized cells produced 7.5 g/l 13‐HODE after 6 h, with a conversion yield of 50 % (w/w) and a volumetric productivity of 1.25 g/l/h. These values were 161 and 160 % of those obtained by nonpermeabilized cells, respectively. To the best of our knowledge, this is the first report on the process optimization for the biotechnological production of 13‐HODE.     

Cells on biomaterials – some aspects of elemental analysis by means of electron probes

Electron probe X‐ray microanalysis enables concomitant observation of specimens and analysis of their elemental composition. The method is attractive for engineers developing tissue‐compatible biomaterials. Either changes in element composition of cells or biomaterial can be defined according to well‐established preparation and quantification procedures. However, the qualitative and quantitative elemental analysis appears more complicated when cells or thin tissue sections are deposited on biomaterials. X‐ray spectra generated at the cell/tissue–biomaterial interface are modelled using a Monte Carlo simulation of a cell deposited on borosilicate glass. Enhanced electron backscattering from borosilicate glass was noted until the thickness of the biological layer deposited on the substrate reached 1.25 μm. It resulted in significant increase in X‐ray intensities typical for the elements present in the cellular part. In this case, the mean atomic number value of the biomaterial determines the strength of this effect. When elements are present in the cells only, the positive linear relationship appears between X‐ray intensities and cell thickness. Then, spatial dimensions of X‐ray emission for the particular elements are exclusively in the range of the biological part and the intensities of X‐rays become constant. When the elements are present in both the cell and the biomaterial, X‐ray intensities are registered for the biological part and the substrate simultaneously leading to a negative linear relationship of X‐ray intensities in the function of cell thickness. In the case of the analysis of an element typical for the biomaterial, strong decrease in X‐ray emission is observed in the function of cell thickness as the effect of X‐ray absorption and the limited excitation range to biological part rather than to the substrate. Correction procedures for calculations of element concentrations in thin films and coatings deposited on substrates are well established in materials science, but little is known about factors that have to be taken into account to accurately quantify bioelements in thin and semi‐thick biological samples. Thus thorough tests of currently available quantification procedures are required to verify their applicability to cells or tissues deposited on the biomaterials.     

Fractality of tics as a quantitative assessment tool for Tourette syndrome

Tics manifest as brief, purposeless and unintentional movements or noises that, for many individuals, can be suppressed temporarily with effort. Previous work has hypothesized that the chaotic temporal nature of tics could possess an inherent fractality, that is, have neighbour-to-neighbour correlation at all levels of timescale. However, demonstrating this phenomenon has eluded researchers for more than two decades, primarily because of the challenges associated with estimating the scale-invariant, power law exponent—called the fractal dimension D_f—from fractional Brownian noise. Here, we confirm this hypothesis and establish the fractality of tics by examining two tic time series datasets collected 6–12 months apart in children with tics, using random walk models and directional statistics. We find that D_f is correlated with tic severity as measured by the YGTTS total tic score, and that D_f is a sensitive parameter in examining the effect of several tic suppression conditions on the tic time series. Our findings pave the way for using the fractal nature of tics as a robust quantitative tool for estimating tic severity and treatment effectiveness, as well as a possible marker for differentiating typical from functional tics.     

Z/M对RFCC催化剂反应性能的影响

以稀土超稳Y型分子筛和拟薄水铝石为主要原料制备了重油催化裂化(RFCC)模型催化剂,通过N 2物理吸附和高级裂化评价装置研究了水热减活RFCC模型催化剂中Y型分子筛与基质比表面积之比(Z/M)及其对催化裂化反应性能的影响。结果表明,拟薄水铝石含量越高,Y型分子筛抵御高温水热破坏的能力越差,Z/M越小。拟薄水铝石质量分数为30%时,水热减活后分子筛比表面积仅为减活前的28.3%,Z/M仅为0.8。拟薄水铝石含量不仅影响催化剂的水热稳定性,还影响催化剂的形貌。拟薄水铝石含量越高,催化剂微球形貌规整性越差,当其质量分数为30%时,催化剂微球表面不仅产生了大量的孔洞,还出现了许多裂纹。随着模型催化剂Z/M下降,目标产物液化石油气和汽油产率之和逐渐降低,轻循环油产率升高,焦炭选择性变差。     

新型低GWP高温热泵工质HFO-1234ze(Z)的研究进展

高温热泵可以有效回收工业余热,达到节能减排和保护环境的目的。目前,有关高温热泵技术的研究热点在于寻找一种全球变暖潜能值(GWP)低、使用性能良好的工质,以替代现有CFC-114、HFC-245fa工质。对新型环境友好型工质HFO-1234ze(Z)进行了综述,其GWP＜1,临界温度高于423 K,是一种潜在的高温热泵替代工质。总结了近年来国内外学者对HFO-1234ze(Z)的合成技术、热力学性质、输运性质、传热性能等方面的研究,并分析了HFO-1234ze(Z)在高温热泵系统中应用的可行性,认为HFO-1234ze(Z)在高温热泵中具有较好的工作性能和发展前景。     

Novel direct Z-scheme AgI/N–TiO2 photocatalyst for removal of polluted tetracycline under visible irradiation

In the study, we doped N into TiO₂ lattice to narrow its band gap energy. Then, the synthesized N doped TiO₂ material was combined with AgI to form AgI/N–TiO₂ (ANT) direct Z scheme materials. The synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e⁻) in N–TiO₂ conduction band tended to combine with the left holes (h⁺) in AgI valence band maintaining h⁺ in the valence band of the N–TiO₂ and e⁻ in the conduction band of the AgI. The remained e⁻ and h⁺ have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N–TiO₂). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N–TiO₂ molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems.     

原纤化过程对纸基空气滤材结构和性能的影响

以木浆为原料,分别采用不同磨浆转数对木浆纤维进行原纤化处理,使其表面分丝帚化,再利用冷冻干燥技术保持纤维表面分丝状态而避免角质化,从而制备出可生物降解的纸基空气过滤材料。研究了不同程度原纤化处理对纸基空气滤材结构和性能的影响,探讨了原纤化处理对滤材Z向形貌的影响机理。结果表明,浆料浓度为1.5%、冷冻温度为-56℃、磨浆转数为50000 r时,纸基空气滤材具有较佳的过滤性能。