Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

大口径主焦点式光学系统轻量化结构设计、分析与试验

针对主焦点式光学系统的特点,对某φ700 mm极轴式望远镜光机结构部分采用模块化设计,分别对主镜室组件、连接镜筒和校正镜镜筒和全系统结构进行了有限元分析与优化,使系统总重不超过700 kg,系统弯沉不超过4".利用平行光管检测系统像质表明,系统80%能力集中度在4×4个像元以内,系统像质理想,符合设计要求,说明该结构设...     

素数域上椭圆曲线快速实现技术研究

随着椭圆曲线公钥密码的广泛应用,怎样快速实现椭圆曲线密码一直是业界关注的重点,在一些应用场景下,如移动、无线领域的应用,对椭圆曲线的实现速度要求较高,目前有许多快速实现椭圆曲线的算法,其性能各有差异.文章全面地研究素数域上的椭圆曲线快速实现技术,如Mersenne素数运算、Fermat定理、Euclidean方法等,并分析了这些方法.在此基础上,给出了详细的素数域上的椭圆曲线完整的实现细节及其关键技术的详细分析和实现方法.用该方法,能快速实现素数域上的椭圆曲线.     

可见光、红外一体化两用相机的光学设计

主要介绍可见光与红外一体化两用相机的光学系统设计.可见光、红外波段公用口径为lm的主镜,可见光波段450～900 nm,采用折轴三反系统,焦距f1=12.0m,视场1.5°×0.5 °,选用TDICCD;红外波段范围8～12 μm,采用主聚焦系统,由主镜和3片锗镜组成,焦距f2＝2.0m,视场2w＝2.0°,采用红外非...     

面尺法求解哥古猜想解答

哥德巴赫猜想与古叶猜想合成哥古猜想（Goldbach-Guye’s Conjecture）：任何一个非零偶数（z）,都可表达为两个素数（y及x）之＂和＂或＂差＂;即有z＋=y＋x,或有z-=y-x。当知z＋或z-时,如何求解y及x配偶成副呢？文章介绍了求解哥古猜想解答的一种面尺法（利用‘定尺’与‘动尺’间的相对位移）,并按参考文献[8]的‘提示’提出了改进措施,使缩尺法更趋完善。     

A review of the antioxidant potential of medicinal plant species

Some researchers suggest that two-thirds of the world's plant species have medicinal value; in particular, many medicinal plants have great antioxidant potential. Antioxidants reduce the oxidative stress in cells and are therefore useful in the treatment of many human diseases, including cancer, cardiovascular diseases and inflammatory diseases. This paper reviews the antioxidant potential of extracts from the stems, roots, bark, leaves, fruits and seeds of several important medicinal species. Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxylanisole (BHA) are currently used as food additives, and many plant species have similar antioxidant potentials as these synthetics. These species include Diospyros abyssinica, Pistacia lentiscus, Geranium sanguineum L., Sargentodoxa cuneata Rehd. Et Wils, Polyalthia cerasoides (Roxb.) Bedd, Crataeva nurvala Buch-Ham., Acacia auriculiformis A. Cunn, Teucrium polium L., Dracocephalum moldavica L., Urtica dioica L., Ficus microcarpa L. fil., Bidens pilosa Linn. Radiata, Leea indica, the Lamiaceae species, Uncaria tomentosa (Willd.) DC, Salvia officinalis L., Momordica Charantia L., Rheum ribes L., and Pelargonium endlicherianum. The literature reveals that these natural antioxidants represent a potentially side effect-free alternative to synthetic antioxidants in the food processing industry and for use in preventive medicine.     

Time-spreading wavelength-hopping optical CDMA system using EWO and TCM

In this paper, time-spreading wavelength-hopping optical CDMA system using trellis coded modulation scheme is investigated. The carrier hopping prime code and its shifted version are employed as signature sequences. Since the carrier hopping prime code is a symmetric code, the out of phase autocorrelation is zero. Applying the orthogonality of the signature sequences, the ternary transmission mechanism can be achieved. The proposed coding scheme is simple in both transmitter and receiver. As the multiple access interference and beat noise are the major deterioration of system performance, using coding scheme is an effective way to reduce the error floor. The numerical results reveal that the proposed coding scheme can significantly improve the system performance.     

On the influence of gamma prime upon machining of advanced nickel based superalloy

Whilst gamma prime (γ′) phase is the strengthening phase in Ni-based superalloys its influence on machining has been seldom investigated. This paper reports for the first time on the effect of γ′ upon machining of Ni-based superalloys when cutting with parameters yielding different cutting temperature intervals which lead to strengthening/softening effects on the workpiece (sub)surface. In-depth XRD, SEM/FIB, EBSD analysis and unique micro-pillar testing in the workpiece superficial layers indicated that with the increase of γ′ fraction the grain plastic deformation significantly decreased, while specific cutting energy can switch from low to high values influenced by the real cutting temperature.     

Mental layout extrapolations prime spatial processing of scenes.

Four experiments examined whether scene processing is facilitated by layout representation, including layout that was not perceived but could be predicted based on a previous partial view (boundary extension). In a priming paradigm (after Sanocki, 2003), participants judged objects' distances in photographs. In Experiment 1, full scenes (target), partial scenes, and two control primes were used. Partial scenes excluded the target objects' locations, but these areas could be predicted. Full and partial scenes produced equal performance facilitation. In Experiment 2, task-irrelevant partial scene primes were also tested. These primes did not facilitate performance (i.e. simple scene previews did not help). Experiment 3 showed that a partial prime's utility depended on the area of the scene that would be tested; the task-irrelevant primes used in Experiment 2 were useful for other distance judgments. Experiment 4 showed that partial scene facilitation is not limited to the area immediately surrounding the prime. The study demonstrated that perceived and mentally extrapolated layouts are equally effective. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

基于超素数的托普利兹观测矩阵构造方法

观测矩阵在信号压缩感知中十分重要,直接决定信号的重构质量。为保证信号的重构精度,要求观测矩阵具有很强的随机性,但随机矩阵硬件实现非常困难;确定性观测矩阵易于实现,但其重构精度不足。针对观测矩阵对随机性与确定性的双重要求,提出利用超素数产生超长周期的伪随机序列,解决确定性观测矩阵对随机性的要求;结合托普利兹观测矩阵的确定性结构特征,得到一种改进的托普利兹观测矩阵。实验仿真表明:改进的托普利兹观测矩阵与高斯随机观测矩阵和常用托普利兹观测矩阵相比,其信号重构精度得到了很好的改善,且易于硬件实现。