水、丙酮混合工质振荡热管传热性能

采用水、丙酮以及其二元混合工质对振荡热管进行实验研究,选取35%～70%充液率,10～100 W加热功率以及水/丙酮13：1、4：1、1：1、1：4、1：13配比,将实验数据与混合工质物性、相变特点结合以研究其振荡热管传热性能。结果表明：混合溶液振荡热管启动所需功率小于水;小充液率时,除较低丙酮比例配比（如水/丙酮13：1混合工质）以外,混合工质比纯工质振荡热管不容易烧干,纯工质振荡热管在50 W时热阻就已经上升到较高数值,而混合工质振荡热管在同样的功率则维持着较低的热阻。在丙酮中加入少量水（如水/丙酮1：13混合工质）能有效改善振荡热管烧干情况,然而,少量丙酮与水混合而成的工质（如水/丙酮13：1混合工质）对振荡热管烧干情况的改善不明显;大充液率时,混合工质振荡热管的传热性能要弱于纯工质,在35～50 W,纯工质振荡热管热阻都低于混合工质,而在较大加热功率（50～100 W）,水与混合工质振荡热管仍保持着较明显的热阻差。对混合工质振荡热管的传热性能的分析可为今后更深入研究其工作机理以及传热特性理论模型的建立提供参考。     

Dropwise Condensation Studies on Multiple Scales

Recent advances in nanotechnology, chemical/physical texturing and thin film coating technology generate definite possibilities for sustaining a dropwise mode of condensation for much longer durations than was previously possible. The availability of superior experimental techniques also leads to deeper understanding of the process parameters controlling the relevant transport phenomena, the distinguishing feature of which is the involvement of a hierarchy of length/time scales, proceeding from nuclei formation, to clusters, all the way to macroscopic droplet ensemble, drop coalescence, and subsequent dynamics. This paper is an attempt to connect and present a holistic framework of modeling and studying dropwise condensation at these multiple scales. After a review of the literature, discussions on the following problems are presented: (i) atomistic modeling of nucleation; (ii) droplet–substrate interaction; (iii) surface preparation; (iv) simulation of fluid motion inside sliding drops; (v) experimental determination of the local/ average heat transfer coefficient; and (vi) a macroscopic model of the complete dropwise condensation process underneath horizontal and inclined surfaces. The study indicates that hierarchal modeling is indeed the way forward to capture the complete process dynamics. The microscopic phenomena at the three-phase contact line, leading to the apparent droplet contact angle, influence the shear stress and heat transfer. The nucleation theory captures the quasi-steady-state behavior quite satisfactorily, although the early atomistic nucleation was not seen to have a profound bearing on the steady-state behavior. The latter is strongly governed by the coalescence dynamics. Visual observation of dropwise condensation provides important information for building hierarchical models.     

Contrasting Local and Macroscopic Effects of Collagen Hydroxylation

Collagen is heavily hydroxylated. Experiments show that proline hydroxylation is important to triple helix (monomer) stability, fibril assembly, and interaction of fibrils with other molecules. Nevertheless, experiments also show that even without hydroxylation, type I collagen does assemble into its native D-banded fibrillar structure. This raises two questions. Firstly, even though hydroxylation removal marginally affects macroscopic structure, how does such an extensive chemical change, which is expected to substantially reduce hydrogen bonding capacity, affect local structure? Secondly, how does such a chemical perturbation, which is expected to substantially decrease electrostatic attraction between monomers, affect collagen’s mechanical properties? To address these issues, we conduct a benchmarked molecular dynamics study of rat type I fibrils in the presence and absence of hydroxylation. Our simulations reproduce the experimental observation that hydroxylation removal has a minimal effect on collagen’s D-band length. We also find that the gap-overlap ratio, monomer width and monomer length are minimally affected. Surprisingly, we find that de-hydroxylation also has a minor effect on the fibril’s Young’s modulus, and elastic stress build up is also accompanied by tightening of triple-helix windings. In terms of local structure, de-hydroxylation does result in a substantial drop (23%) in inter-monomer hydrogen bonding. However, at the same time, the local structures and inter-monomer hydrogen bonding networks of non-hydroxylated amino acids are also affected. It seems that it is this intrinsic plasticity in inter-monomer interactions that preclude fibrils from undergoing any large changes in macroscopic properties. Nevertheless, changes in local structure can be expected to directly impact collagen’s interaction with extra-cellular matrix proteins. In general, this study highlights a key challenge in tissue engineering and medicine related to mapping collagen chemistry to macroscopic properties but suggests a path forward to address it using molecular dynamics simulations.     

Nanoenergetic Composite of Mesoporous Iron Oxide and Aluminum Nanoparticles

Ordered mesoporous Fe₂O₃ was synthesized using cetyltrimethylammonium chloride (CTAC) and polyethylene glycol octadecyl ether (Brij 76) surfactant templates. The gel time was monitored as a function of the concentration ratio of precursor to the surfactant. As-prepared FeOOH gels were extracted in ethanol to remove the surfactant and calcined at 200–400°C for 6 h so that α-Fe₂O₃ is produced. The FTIR spectra of these gels reveal complete removal of surfactant and water impurities and the presence of Fe-O vibrations. TEM images show ordering of mesopores in the gels prepared using surfactant templating and no ordering of the pores in the gels prepared without surfactant. The gels after calcinations were mixed with aluminum nanoparticles to prepare nanoenergetic composites. The burn rate of the nanocomposites containing ordered mesoporous Fe₂O₃ mixed with Al nanoparticles was compared with the one containing Fe₂O₃ with no ordering of mesopores and Al nanoparticles.     

Development and validation of a simple analytical method for the determination of 2,4,6-trichloroanisole in wine by GC–MS

A novel method for the residue analysis of wine spoilage compound 2,4,6-trichloroanisole is reported. Wine (60 ml) was extracted with 2 ml toluene in presence of 24 g MgSO₄ and 6 g NaCl. Cleanup of the toluene phase by dispersive solid phase extraction with mixture of 100 mg CaCl₂, 25 mg primary secondary amine and 50 mg MgSO₄ was effective in minimising co-extractives and matrix effects. Time-of-flight and tandem mass spectrometric parameters were optimised to achieve linearity over 0.25–500 ng ml⁻¹ and method detection limit 0.0083 ng ml⁻¹ which is well below the odour threshold of 0.04 ng ml⁻¹. Recoveries at 0.04, 0.2 and 0.8 ng ml⁻¹ were within 80–110% (±8%). The method was reproducible when tested for Argentinean wines with intra-laboratory Horwitz ratios being <0.20 in white and red wines at both the laboratories of India and Argentina. The method could be successfully applied for incurred wine samples.     

Correction to: Detection of Epileptical Seizures Based on Alpha Band Statistical Features

Intra-WBSN are generally short range wireless health monitoring networks, consisting of strategically placed miniaturized, intelligent and low powered bio-sensors. They perform various applications in healthcare, fitness, military, sport and consumer electronics. The network stability and the network longevity of such networks have prime focus in current research. Routing schemes have a significant potential to make such network energy efficient by sending the sensing data properly and promptly. In this paper, we have proposed a relay based cooperative routing scheme to achieve high energy efficiency. Sensing data from the bio-sensor node have been delivered on the basis data priority. The sensing data with high priority has been directly transmitted to body network controller (BNC). The delivery of normal sensing data from bio-sensor to the BNC through relay nod or cooperative node. These nodes are deployed in clothes, they can be easily replaced or recharged, it provide effective, easy and comfortable health monitoring. Through simulation results, the proposed routing protocol achieved improved performance in terms of energy efficiency, network stability, network lifetime, path-loss and throughput in comparison to the existing routing schemes.

     

A 0.5 V bulk-input OTA with improved common-mode feedback for low-frequency filtering applications

This paper presents the design of a two-stage pseudo-differential operational transconductance amplifier (OTA) and its application in low-frequency continuous time filters. The OTA was designed in a 0.18 μm, 0.45 V V _T CMOS process. An improved bulk-mode common-mode feedback (CMFB) circuit has been designed which does not load the OTA compared to prior art. A self cascode load structure and partial positive feedback provide higher gain. The bulk terminals of all transistors have been biased to lower their threshold voltages (V_T) and maximize signal swing. The OTA operates at a supply voltage of 0.5 V and consumes only 28 μW of power. Rail-to-rail input is made possible by using the transistor’s bulk terminal as the input. For a load of 20 pF the OTA has a measured DC gain of 63 dB and a gain-bandwidth product of 570 kHz. To demonstrate the use of the OTA in practical circuits, three active RC filters were designed: a 10 kHz Butterworth filter, a 10 kHz Bessel filter, and a 2.5 kHz Tschebycheff filter.     

DAO数据库应用程序安装系统的设计和制作

介绍了ＤＡＯ应用程序所必需的运行库以及通用Ｉnstall Shield来制作ＤＡＯ数据库应用程序安装系统的详细方法和步骤。