Mechanical Stress on Lysozyme Crystals during Dynamic Cross‐Flow Filtration

The influence of mechanical stress on the crystal size distribution of lysozyme crystal slurries in a dynamic cross‐flow device is discussed. The reduction of crystal size may have an influence on mass and resistance of the fouling layer. A filter test device with a filter area of 130 cm² is used for thickening. After thickening, a model impurity, namely bovine serum albumin, is washed out of the suspension. A reduction of crystal size due to stirring and a reduced fouling layer with increasing stirrer speed is observed. Furthermore, a higher stirring speed increases the specific filtrate flux. In the presence of the impurity, more crystal aggregates than single isometric crystals are formed and, hence, the decrease of crystal size due to shear forces is more pronounced than without impurity.     

Influence of post-curing temperature on the structure,properties, and adhesion of vinyl ester adhesive

Vinyl ester (VE) resins are widely used as thermoset adhesives in structural joints and composites, but complete curing under environmental conditions is not produced. The existing literature dealing with the effect of post-curing on the structure, viscoelastic, mechanical, and adhesion properties of VE resin is scarce. Therefore, in this study, VE resin was subjected to different post-curing temperatures (50–140 °C) for one hour, and the changes in structure and properties were assessed. The degree of cross-linking of the VE resin depended on the post-curing temperature and cure started to be completed above 100 °C, a temperature close to the glass transition temperature (115 °C) of the completely cross-linked polymer. Furthermore, gel formation in VE resin was evidenced for post-curing temperature below 100 °C. In order to fully cross-link the VE resin, post-curing at 140 °C for one hour was necessary, and it was evidenced by an increase in the glass transition temperature and in the mechanical properties; an increase in adhesion to cold rolled steel was obtained although the shear strength was lower than in the joint produced with the non-post-cured VE resin.     

Nd: Bi4Ge3O12 crystal growth by czochralski method

Nd-doped Bi₄Ge₃O₁₂ (Nd:BGO) crystals were successfully grown in the auto-diameter control system equipped with a frequency weighing sensor with the Czochralski method. The Nd³⁺ ion doping level was varied from 0.25 to 2.5 at.%. The crystals were transparent and of light purple color, with a typical size of about 20 mm in diameter and 50 mm in length. The effective distribution coefficient (k_eff) of Nd³⁺ ion was about 0.957 irrespective of concentration, and the Nd³⁺ ions were distributed homogeneously throughout the crystal. The doping concentration (p_i) of active ion in Nd:BGO crystal was 2.54x10²⁰ ions/cm³, which is higher than that in the Nd:YAG crystal. Therefore, the Nd:BGO crystal was judged to be more suitable for the laser diode pumping microchip laser material where size reduction was desirable.     

用8031，DRAM和高速A/D实现快速数据采集

介绍了一个用８０３１，ＤＲＡＭ和高速Ａ／Ｄ等芯片构成的快速数据采集系统。该系统使Ａ／Ｄ转换的数据不经ＣＰＵ“中转”，而直接存入ＤＲＡＭ中。它具有硬件结构简单、价格低廉、易实现大容量存储等优点。本系统对模拟信号的采集并将采集数据送入存储器的周期为８μｓ。     

Quantitative electron spectroscopic diffraction analyses of the crystal formation in dentine

Newly formed apatitic crystallites of different hard tissues consist, according to our investigations, of chains composed of nanometre-sized particles (islands, dots) arising at nucleating sites of the collagenous and noncollagenous matrix macromolecules. In dentine these islands coalesce rapidly in longitudinal direction to form needle-like crystallites which further coalesce to ribbon-like crystallites. We have concluded that the centre-to-centre distances between these islands represent the distances between the nucleating sites of the matrix macromolecules. We have applied energy-filtering transmission electron microscopy in the selected area electron diffraction mode at different stages of crystal formation in dentine and have obtained quantitative information of the degree of crystal disorder on the basis of the paracrystal theory. The fluctuation of the lattice plane distances in c -axis direction decreases, proceeding from the region near the dentine/predentine border to the dentine/enamel border.     

Viewing angle performance of TN-LCD with hybrid aligned nematic film

We developed a novel hybrid aligned nematic film that improves viewing angle performance of twisted nematic liquid crystal display (TN-LCD). The viewing angle performance of the normally white (NW) TN-LCD with the compensation film was evaluated by both computer simulation and experiment. The compensated NW-TN-LCD exhibits wide viewing angle performance including good gray scale stability and low color shift.     

Study of the mechanical properties of TiCN–WC–CO hardmetals by the interpretation of internal friction spectra

TiCN–WC–Mo–Co mixed carbide hardmetals have an interesting application potential for cutting tool fabrication combining the high toughness of WC–Co with the resistance to plastic deformation of TiCN–Co cermets. Mechanical spectroscopy (MS) is used in order to separate the effects of the constituents on the mechanical properties. Internal friction (IF) spectra are measured in a torsion pendulum on WC–TiCN–Mo–Co samples where TiCN/WC ratio is varied as well as the Co content. Six components of the characteristic IF spectrum of WC–TiCN–Mo–Co have been identified and interpreted. Two peaks are located in the cobalt, two peaks in the TiCN phase and two peaks in the ceramic grain boundaries. Four temperature domains are defined depending on the mechanical behaviour: brittle (I), anelastic (IIa), limited plasticity (IIb) and extended plasticity (III). The anelastic domain is characterized by the bulk deformation of cobalt. In the limited plasticity domain, both cobalt and TiCN are deformed by dislocation movement. The high temperature extended plasticity should be attributed to grain boundary sliding in the ceramic phase (mainly WC) enhanced by cobalt diffusion in the grain boundaries.     

电解法制取金属铬粉工艺研究

文章分析了电解法制取金属铬的工艺,对其中除铁、冷冻、电解三个工序进行了重点研究,得出了完善工艺流程的办法。     

单孔复合锚固法的理论和实践

论述了单孔复合锚固法的基本原理、工作机理和工程实践。与传统的锚固法相比 ,单孔复合锚固法能将荷载分散地传递给钻孔内的几个较短的固定段 ,不会发生粘结效应逐步弱化或“脱开”现象 ,能有效地调用天然地层强度 ,显著地提高锚杆承载力。并指出了传统锚杆设计中 ,将固定长度上杆体与注浆体 ,注浆体与地层之间的粘结应力视为均匀分布是不合理的。在计算锚杆承载力时 ,应引入固定长度有效因子这一概念。     

Amorphization and graphitization of single-crystal diamond — A transmission electron microscopy study

The amorphization and graphitization of single-crystal diamond by ion implantation were explored using transmission electron microscopy (TEM). The effect of ion implantation and annealing on the microstructure was studied in (100) diamond substrates Si⁺ implanted at 1 MeV. At a dose of 1 × 10¹⁵ cm^− 2, implants done at 77 K showed a damage layer that evolves into amorphous pockets upon annealing at 1350 °C for 24 h whereas room temperature implants (303 K) recovered to the original defect free state upon annealing. Increasing the dose to 7 × 10¹⁵ Si⁺/cm² at 303 K created an amorphous-carbon layer 570 ± 20 nm thick. Using a buried marker layer, it was possible to determine that the swelling associated with the amorphization process was 150 nm. From this it was calculated that the layer while obviously less dense than crystalline diamond was still 15% more dense than graphite. Electron diffraction is consistent with the as-implanted structure consisting of amorphous carbon. Upon annealing, further swelling occurs, and full graphitization is achieved between 1 and 24 h at 1350 °C as determined by both the density and electron diffraction analysis. No solid phase epitaxial recrystallization of diamond is observed. The graphite showed a preferred crystal orientation with the (002)g//(022)d. Comparison with Monte Carlo simulations suggests the critical displacement threshold for amorphization of diamond is approximately 6 ± 2 × 10²² vacancies/cm³.