Ion beam machining error control and correction for small scale optics

Ion beam figuring (IBF) technology for small scale optical components is discussed. Since the small removal function can be obtained in IBF, it makes computer-controlled optical surfacing technology possible to machine precision centimeter- or millimeter-scale optical components deterministically. Using a small ion beam to machine small optical components, there are some key problems, such as small ion beam positioning on the optical surface, material removal rate, ion beam scanning pitch control on the optical surface, and so on, that must be seriously considered. The main reasons for the problems are that it is more sensitive to the above problems than a big ion beam because of its small beam diameter and lower material ratio. In this paper, we discuss these problems and their influences in machining small optical components in detail. Based on the identification-compensation principle, an iterative machining compensation method is deduced for correcting the positioning error of an ion beam with the material removal rate estimated by a selected optimal scanning pitch. Experiments on ?10?mm Zerodur planar and spherical samples are made, and the final surface errors are both smaller than λ/100 measured by a Zygo GPI interferometer.     

离子液体对酶原位降解微晶纤维素的促进作用

构建离子液体1-乙基-3-甲基咪唑醋酸盐[EMIM]OAc与纤维素的均相体系,采用酶原位降解法,以3,5-二硝基水杨酸法表征降解效果,考察各因素的影响确定最佳工艺条件:6.6 g 3%(质量分数)原溶液与4 mL pH4.6柠檬酸钠缓冲溶液组成均相体系、6 mg酶、50℃、26 h,酶解率迭78.5%,比非均相下提高了...     

耦合物理场CVI 快速增密C/ C复合材料及动力学探讨

采用多元耦合物理场CVI 工艺, 用炭毡作为增强体, 在增强体中设计导电层, 产生温度场和电磁场梯度, 在自行设计的CVI 炉中增密C/ C 复合材料, 对温度、系统压力和气体流量等工艺进行了优化; 采用偏光显微镜研究了热解炭的显微结构; 用X射线衍射研究了材料的石墨化度; 探讨了本工艺中的有内热源和无内热源的二元传热机制, 多元耦合物理场的有机耦合对“消耗传质”的抑制作用, 以及电磁场对沉积的影响和3 种典型的生长模型。研究表明, 多元耦合物理场CVI 增密速度快, 初始密度为0.2 g/ cm3 , 尺寸为260 mm ×60 mm ×20 mm 的增强体, 在920 ℃、4 kPa 条件下沉积20 h , 试样可增密到1.71 g/ cm3 ; 可获得粗糙层结构(RL) 、光滑层结构(SL) 、带状结构(Banded st ructure) 等热解炭的结构, 在960 ℃、0.1 kPa 条件下可获得较高织构的粗糙层结构。      

GC-MS法同时测定橡皮擦中22种邻苯二甲酸酯增塑剂

建立了气相色谱-质谱(GC-MS)分段选择离子监测(SIM)模式分析同时测定橡皮擦中22种邻苯二甲酸酯(PAEs)增塑剂含量的方法。该方法具有良好线性,相关系数R均大于0.999,检测限在1.3 mg/kg～128.9 mg/kg之间,平均回收率在70.2%～105.6%,相对标准偏差在2.57%～9.88%之间。通过该方法对国内橡皮擦中PAEs增塑剂进行检测,实际样品均检出邻苯二甲酸二(2-乙基)己酯(DEHP),含量最高达32.5%。     

Ferroelectric Localized Field–Enhanced ZnO Nanosheet Ultraviolet Photodetector with High Sensitivity and Low Dark Current

Zinc oxide (ZnO) nanosheets have demonstrated outstanding electrical and optical properties, which are well suited for ultraviolet (UV) photodetectors. However, they have a high density of intrinsically unfilled traps, and it is difficult to achieve p‐type doping, leading to the poor performance for low light level switching ratio and a high dark current that limit practical applications in UV photodetection. Here, UV photodetectors based on ZnO nanosheets are demonstrated, whose performance is significantly improved by using a ferroelectric localized field. Specifically, the photodetectors have achieved a responsivity of up to 3.8 × 10⁵ A W^?1, a detectivity of 4.4 × 10¹⁵ Jones, and a photocurrent gain up to 1.24 × 10⁶. These device figures of merit are far beyond those of traditional ZnO ultraviolet photodetectors. In addition, the devices' initial dark current can be easily restored after continuous photocurrent measurement by using a positive gate voltage pulse. This study establishes a new approach to produce high‐sensitivity and low‐dark‐current ultraviolet photodetectors and presents a crucial step for further practical applications.     

A prediction method for fatigue life of large moving components as function of scale factor: A case of motor‐generator rotor

With the development of science and technology, more and more large moving components have been used in industry, and their service lives have become an important issue. After analysis of the previous results, considering the scale factor, a prediction method for fatigue life of large moving components based on the Basquin relation was proposed at first, and then the magnet pole part of motor‐generator rotor was chosen to make simulation parts with different scale factors mainly in terms of their S‐N curves and fractographies. It was found that with the change of specimen scale factor, the stress concentration factor at transition arc is almost unchanged as well as the fatigue strength exponent, and the fatigue strength coefficient changes linearly. Based on those results, a life prediction method was validated, and the results show that this method is a simple but more precise relation. After fatigue fracture surface and crack growth angle observations and quantitative analyses, the fatigue damage mechanisms associated with the relation among fatigue strength exponent and coefficient and scale factors were explained well. Those studies will provide a new clue to the prediction of the service life for those large moving components.     

Biomimetic Robust Starch Composite Films with Super-Hydrophobicity and Vivid Structural Colors

The starch composite films (SCFs) will be one of the best alternative packaging materials to petroleum based plastic films, which mitigates white pollution and energy consumption. However, weak mechanical stability, water resistance, and dyeability has hindered the application of SCFs. Herein, a bioinspired robust SCFs with super-hydrophobicity and excellent structural colors were prepared by fiber-reinforcement and assembling SiO₂/Polydimethylsiloxane (PDMS) amorphous arrays on the surface of SCFs. The properties of the designed SCFs were investigated by various methods including scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), a tensile test, contact angle (CA) test, and an optical test. The results showed that the obtained SCFs possessed a higher tensile strength (55.17 MPa) attributed to the formed abundant hydrogen bonds between the molecular chains of the starch, cellulose fiber, and polyvinyl alcohol. Benefiting from the nanostructure with rough surface which were modified by materials with low surface free energy, the contact angle and sliding angle of the film reached up to 154° and 2°, respectively. The colors which were produced by the constructive interference of the coherent scattered light could cover all of the visible regions by tuning the diameters of the SiO₂ nanoparticles. The strategy in the present study not only reinforces the mechanical strength and water resistance of SCFs but also provides an environmentally friendly way to color the them, which shows unprecedented application potential in packaging materials of the starch composite films.     

江西省在用古代水利工程概况及保护现状

江西省位于长江中下游交接处的南岸,自古以来就享有“鱼米之乡”的美誉,水资源丰富,水利工程种类繁多,历朝历代修筑的水利工程数量众多.本文综合运用文献法、实地调研法、比较分析法等方法,以江西省在用古代水利工程为研究对象,全面分析和总结江西省在用古代水利工程的发展历史、现状及存在的问题,以期为江西省水文化遗产保护与利用工作的开展提供科学依据.     

江西省泰和县槎滩陂水利工程的保护与利用研究

地处赣江流域吉泰盆地的槎滩陂水利工程始筑于南唐(937～975年),仍持续发挥灌溉功能,是目前江西省唯一的世界灌溉工程遗产.槎滩陂建在林木葱郁的千年古村泰和县螺溪镇爵誉村境内,具有打造成国家级水利风景区的潜力.但目前槎滩陂保护利用措施明显不足,本文通过总结归纳前人丰富的经验,提出保护性利用槎滩陂水利遗产的建议.在保护中开发,在开发中利用,将槎滩陂水利遗产传承千年仍造福百姓的灌溉功能传承下去,并在开发成为水利风景区挖掘生态旅游功能方面进行探索,将槎滩陂打造成为多功能的国家级水利风景区.