Synthesis of Amido‐N‐imidazolium Salts and their Applications as Ligands in Suzuki–Miyaura Reactions: Coupling of Hetero‐ aromatic Halides and the Synthesis of Milrinone and Irbesartan

A new catalytic system based on palladium‐amido‐N‐heterocyclic carbenes for Suzuki–Miyaura coupling reactions of heteroaryl bromides is described. A variety of sterically bulky, amido‐N‐imidazolium salts were synthesized in high yields from the corresponding anilines. This catalytic system effectively promoted Suzuki–Miyaura couplings of heteroaryl bromides and chlorides with a range of boronic acids to give the corresponding aryl compounds in high yield. The yield was increased with increasing steric bulkiness of the substituted group. Especially, 1‐(2,6‐diisopropylphenyl)‐3‐N‐(2,4,6‐tri‐tert‐butylphenylacetamido)imidazolium bromide ( 4bc ) exhibited 850,000 TON in the coupling reaction of 2‐bromopyridine and phenylboronic acid. In addition, pharmaceutical compounds such as milrinone and irbesartan were synthesized via Suzuki–Miyaura coupling using sterically bulky, amido‐N‐imidazolium salt ( 4bc ) as a ligand.     

Multiuser MIMO OFDM Based TDD/TDMA for Next Generation Wireless Communication Systems

Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (MIMO OFDM) is an attractive air-interface solution for next-generation wireless local area networks (WLANs), wireless metropolitan area networks (WMANs), and fourth-generation mobile cellular wireless systems. In this paper, one multiuser MIMO OFDM systems with TDD/TDMA was proposed for next-generation wireless mobile communications, i.e., TDD/TDMA 4G, which can avoid or alleviate the specific limitations of existing techniques designed for multiuser MIMO OFDM systems in broadband wireless mobile channel scenarios, i.e., bad performance and extreme complexity of multiuser detectors for rank-deficient multiuser MIMO OFDM systems with CDMA as access modes, extreme challenges of spatial MIMO channel estimators in rank-deficient MIMO OFDM systems, and exponential growth complexity of optimal sub-carrier allocations for OFDMA-based MIMO OFDM systems. Furthermore, inspired from the Steiner channel estimation method in multi-user CDMA uplink wireless channels, we proposed a new design scheme of training sequence in time domain to conduct channel estimation. Training sequences of different transmit antennas can be simply obtained by truncating the circular extension of one basic training sequence, and the pilot matrix assembled by these training sequences is one circular matrix with good reversibility. A novel eigenmode transmission was also given in this paper, and data symbols encoded by space–time codes can be steered to these eigenmodes similar to MIMO wireless communication systems with single-carrier transmission. At the same time,, an improved water-filling scheme was also described for determining the optimal transmit powers for orthogonal eigenmodes. The classical water-filling strategy is firstly adopted to determine the optimal power allocation and correspondent bit numbers for every eigenmode, followed by a residual power reallocation to further determine the additional bit numbers carried by every eigenmode. Compared with classical water-filling schemes, it can also obtain larger throughputs via residual power allocation. At last, three typical implementation schemes of multiuser MIMO OFDM with TDMA, CDMA and OFDMA, i.e., TDD/TDMA 4G, VSF-OFCDM and FuTURE B3G TDD, were tested by numerical simulations. Results indicated that the proposed multiuser MIMO OFDM system schemes with TDD/TDMA, i.e., TDD/TDMA 4G, can achieve comparable system performance and throughputs with low complexity and radio resource overhead to that of DoCoMo MIMO VSF-OFCDM and FuTURE B3G TDD.     

A Novel FRFT Beamformer for Rayleigh Faded Channels

A method of optimal beamforming for flat Rayleigh faded channels using the Fractional Fourier Transform (FRFT) is considered in this paper. It has been demonstrated through simulations that optimal beamforming with FRFT allows smaller mean-square errors in restoring signals degraded with linear time-or frequency variant distortions and Additive White Gaussian Noise. This is made possible by the additional flexibility that comes with free parameter ‘a’ of the fractional Fourier transform as oppose to the classical Fourier transform (FT). The method is especially useful in moving source problems, where Doppler Effect produces frequency shift when the source is moving, as in mobile and wireless communication where user produces the frequency shift while moving. In this paper it is shown through simulations that beamforming in fractional domain reduces BER as compared to time or frequency domain.     

建立投资风险管理体系，立对3G时代多网络建设

3G时代,电信运营商经营的网络建设范围向移动＋固定网络,2G＋3G网络发展,网络结构愈加复杂。电信运营商投资控制难度不断加大,投资风险也逐渐升高。电信运营商需要加强投资风险管理意识．建立一套从规划层面到项目管理、贯穿投资前中后各个环节的投资风险管理体系,从而降低整体投资风险,提升投资效率。     

基于HCI层的蓝牙开发

本文对蓝牙的体系结构、主机控制器接口(HCI)层及HCI指令和HCI事件进行了简要介绍,探讨了基于HCI层的蓝牙开发模式,阐述了蓝牙点对点的ALC数据传输的主要过程,提出了蓝牙HCI指令函数封装的一般方法,为蓝牙的嵌入式应用开发提供一般思路。     

帕卡特水电站设计径流量计算

通过建立月降雨径流模型,采用月降雨量推求月径流量,并考虑了与产生径流量有关的气象要素和流域相关参数,对帕卡特水电站的设计径流量进行了计算。     

西枝江水利枢纽工程建设水资源论证有关内容分析

对西枝江水利枢纽工程工程区域水资源时空分布特点及开发利用现状进行了分析,并对工程的取水地点、取水量、取水方式及用水、退水方式进行了研究,分析了该工程的用水和退水对周边环境和其他用水户的影响,论证了工程开发取水的合理性,并提出水资源保护措施和建议。     

利用解析法计算倒垂孔有效孔径及中心的改进方法

解析法在计算倒垂孔有效孔径及中心时逐步受到重视。通过对倒垂孔有效孔径的求解过程进行几何分析和理论归纳,提出一种改进的计算倒垂孔有效孔径和中心的解析方法,并给出基于Visual Basic计算机语言的算法框图。根据该方法开发了一套实用性强的计算程序,可以快速、精确地计算有效孔径和中心,并已在工程实际应用中得到验证,取得了良好效果。     

脂肪替代品的现状及展望

概述了脂肪替代品的发展现状、基本类型以及它们各自的特点和应用范围。并提出脂肪替代品的发展趋势和前景     

Solid waste removes toxic liquid waste: adsorption of chromium(VI) by iron complexed protein waste

The leather processing industry generates huge amounts of wastes, both in solid and liquid form. Fleshing from animal hides/skins is one such waste that is high in protein content. In this study, raw fleshing has been complexed with iron and is used for removal of chromium(VI). The effect of pH and the initial concentration of chromium(VI) on the removal of Cr(IV) by iron treated fleshing is presented. Iron treatment is shown to greatly improve adsorption of the fleshing for hexavalent chromium. The ultimate adsorption capacity of iron treated fleshing is 51 mg of chromium(VI) per gram of fleshing. That of untreated fleshing is 9 mg/g such that iron treatment increases the adsorption capacity of fleshing by 10-fold. The measured adsorption kinetics is well described by a pseudo-second-order kinetic model. The uptake of chromium(VI) by fleshing is best described by the Langmuir adsorption isotherm model. X-ray photoelectron spectroscopic (XPS) studies show that the iron is incorporated into the protein matrix. Shifts in XPS spectra suggest that dichromate binding occurs with iron at active adsorption sites and that iron treated fleshing removes chromium(VI) without reducing it to chromium(III).