Preparation of polyethers by phase transfer catalyzed polycondensation

Polyethers have been prepared by solution polycondensation of bisphenol A with an aromatic or an aliphatic dichloride, using phase transfer catalysis method.     

Force control for hydraulic load simulator using self-tuning grey predictor – fuzzy PID

Hydraulic systems play an important role in modern industry for the reason that hydraulic actuator systems have many advantages over other technologies with electric motors, as they possess high durability and the ability to produce large forces at high speeds. Therefore, the hydraulic actuator has a wide range of application fields such as hydraulic punching, riveting, pressing machines, and molding technology, where controlled forces or pressures with high accuracy and fast response are the most significant demands. Consequently, many hybrid actuator models have been developed for studying how to control forces or pressures with best results.This paper presents a kind of hydraulic load simulator for conducting performance and stability testing related to the force control problem of hydraulic hybrid systems. In the dynamic loading process, perturbation decreases control performance such as stability, frequency response, and loading sensitivity decreasing or bad. In order to improve the control quality of the loading system while eliminating or reducing the disturbance, a grey prediction model combined with a fuzzy PID controller is suggested. Furthermore, fuzzy controllers and a tuning algorithm are used to change the grey step size in order to improve the control quality. The grey prediction compensator can improve the system settle time and overshoot problems. Simulations and experiments on the hydraulic load simulator are carried out to evaluate the effectiveness of the proposed control method when applied to hydraulic systems with various external disturbances encountered in real working conditions.     

新型红砖GRC复合板幕墙设计介绍

本文介绍了一种新型红砖GRC复合板幕墙的结构构造、施工要点和试验检验方案,供同类工程参考。     

Viscous heating and temperature profiles of liquid water flows in copper nanochannel

Journal of Mechanical Science and Technology - Understanding nanoscale fluidic transport becomes increasingly important due to the rapid development of nanotechnology and nanofabrication. By using...     

Cholesterol Content and Methods for Cholesterol Determination in Meat and Poultry

Abstract: Available data for cholesterol content of beef, pork, poultry, and processed meat products were reported. Although the cholesterol concentration in meat and poultry can be influenced by various factors, effects of animal species, muscle fiber type, and muscle fat content are focused on in this review. Oxidative red muscles tend to have greater total lipid and cholesterol contents, although differences in the same types of muscles or cuts have been reported. Moreover, contradictory results among various studies suggest that unless there are pronounced changes in muscle structure and composition, cholesterol content is unlikely to be affected. Second, multiple issues in cholesterol analysis, including sample preparation, detection, and quantification, were evaluated. Cholesterol content of meat and poultry has been determined mostly by colorimetry and chromatography, although the latter has become predominant because of technological advances and method performance. Direct saponification has been the preferred method for hydrolyzing samples because of cost‐ and time‐effectiveness. The extraction solvent varies, but toluene seems to provide sufficient recovery in a single extraction, although the possible formation of an emulsion associated with using toluene requires experience in postsaponification manipulation. The most commonly used internal standard is 5α‐cholestane, although its behavior is not identical to that of cholesterol. Cholesterol can be analyzed routinely by gas chromatography (GC)‐flame ionization detector without derivatization; however, other methods, especially high‐performance liquid chromatography (HPLC) coupled with different detectors, can also be used. For research purposes, HPLC‐ultraviolet/Visible/photodiode array detector with nondestructiveness is preferred, especially when cholesterol must be separated from other coexisting compounds such as tocopherols. More advanced methods, such as GC/HPLC‐isotope dilution/mass spectrometry, are primarily used for quality control purposes.     

Synthesis, Crystal Structure and Interaction With DNA of N,N'-(Butane-1,4-Diyl)Bis(Guanidinium) Tetrachloroplatinate (II)

The design, synthesis, crystal structure and interaction with DNA of the N,N'-(butane-1,4-diyl)bis(guanidinium) tetrachloroplatinate(ll) are described. Crystal data: a = 8.152(1), b = 8.889(4), c = 10.700(3) A , alpha = 81.59(3), beta = 87.99(5), gamma = 78.48(6) degrees , V = 752(1) A(3), Z = 2 , space group P-1. The structure was refined to R = 0.039 and Rw = 0.046 from 1853 reflections (I > 3sigma(I)). This compound, named PtC(4)Gua, does not exhibit a center of symmetry and the center linker chain C(2) - C(3) - C(4) - C(5) is in gauche conformation. The cation is bisprotonated with the H(+) attached to the imine group of each terminal guanidinium function. The presence of the platinum moiety reinforces the binding of the butane(bis)guanidinium structure with double stranded DNA as judged from thermal denaturation studies and DNA unwinding experiments.     

Advances in Rational Design and Materials of High‐Performance Stretchable Electromechanical Sensors

Stretchable and wearable sensor technology has attracted significant interests and created high technological impact on portable healthcare and smart human–machine interfaces. Wearable electromechanical systems are an important part of this technology that has recently witnessed tremendous progress toward high‐performance devices for commercialization. Over the past few years, great attention has been paid to simultaneously enhance the sensitivity and stretchability of the electromechanical sensors toward high sensitivity, ultra‐stretchability, low power consumption or self‐power functionalities, miniaturisation as well as simplicity in design and fabrication. This work presents state‐of‐the‐art advanced materials and rational designs of electromechanical sensors for wearable applications. Advances in various sensing concepts and structural designs for intrinsic stretchable conductive materials as well as advanced rational platforms are discussed. In addition, the practical applications and challenges in the development of stretchable electromechanical sensors are briefly mentioned and highlighted.     

Layered Oxide Cathode for Potassium‐Ion Battery: Recent Progress and Prospective

Rechargeable potassium‐ion batteries (KIBs) have demonstrated great potential as alternative technologies to the currently used lithium‐ion batteries on account of the competitive price and low redox potential of potassium which is advantageous to applications in the smart grid. As the critical component determining the energy density, appropriate cathode materials are of vital need for the realization of KIBs. Layered oxide cathodes are promising candidates for KIBs due to high reversible capacity, appropriate operating potential, and most importantly, facile and easily scalable synthesis. In light of this trend, the recent advancements and progress in layered oxides research for KIBs cathodes, covering material design, structural evolution, and electrochemical performance are comprehensively reviewed. The structure–performance correlation and some effective optimization strategies are also discussed. Furthermore, challenges and prospects of these layered cathodes are included, with the purpose of providing fresh impetus for future development of these materials for advanced energy storage systems.