High-sensitivity and wide-directivity ultrasound detection using high Q polymer microring resonators

Small size ultrahigh Q polymer microrings working at near visible wavelength have been experimentally demonstrated as ultralow noise ultrasound detectors with wide directivity at high frequencies (>20 MHz). By combining a resist reflow and a low bias continuous etching and passivation process in mold fabrication, imprinted polymer microrings with drastically improved sidewall smoothness were obtained. An ultralow noise-equivalent pressure of 21.4 Pa over 1-75 MHz range has been achieved using a fabricated detector of 60 μm diameter. The device's wide acceptance angle with high sensitivity considerably benefits ultrasound-related imaging.     

Rearrangement/Fragmentation Reactions of Oligosilanes with Aluminum Chloride

Reinvestigation of the Lewis acid catalyzed rearrangement of some open-chain permethyloligosilanes with the Al(Fe)Cl(3) catalyst system exhibited several cases of additional reactivity: namely, a fragmentation/cyclization reaction. Introduction of (trimethylsilyl)methyl substituents into the oligosilane substrates strongly facilitated this reaction, yielding cyclic or bicyclic carbacyclosilanes. Investigations concerning the composition of the catalyst system indicated that the incorporation of about 0.1% FeCl(3) into the AlCl(3) lattice provided an effective catalyst.     

Photoanode Activity of ZnO Nanotube Based Dye-Sensitized Solar Cells

Vertical ZnO nanotube (ZNT) arrays were synthesized onto an indium doped tin oxide (ITO) glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy (SEM) showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a largearea. X-ray diffraction (XRD) of ZNT layer showed substantially higher intensity for the (0002) diffractionpeak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements ofthe ZNT layer showed an average thickness of ～7 μm. Diameter size distribution (DSD) analysis showedthat ZNTs exhibited a narrow diameter size distribution in the range of 65–120 nm and centered at ～75nm. The photoluminescence (PL) spectrum measurement showed violet and blue luminescence peaks thatwere centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet (UV)spectroscopy showed major absorbance peak at ～348 nm, exhibiting an increase in energy gap value of 3.4 eV.By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell (DSSC), a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximumof incident photon-to-electron conversion efficiency in a visible region located at 520–550 nm range.     

A Chinese information processing system

The Chinese information processing system(CIPS)introduced in this paper can producegraphs,tables,flowcharts,mathematical equations,forms and also provides typesettingfacilities.The system can process not only Chinese text but also English text or a mixture ofthem.It is written in C language and runs on VAX Ⅱ/780 under Unix operating system.TheCIPS system is very easy to use and provides user-defined macro which allows abbreviationsof commonly used Chinese phrases and reduce the complexity of Chinese characters coding.     

生物质用于焦炭和烧结生产的实验室评价

生物质作为碳可供选择的环保替代燃料,用其进行炼焦和炼铁是一个非常好的选择,因此,应该积极调查、研究如何采取不同的方法利用生物质,以减少硫化物、氮氧化物、二氧化碳的排放和可能的成本投入。对生物质在炼焦生产与烧结生产中的实用性在独立的试验中进行评估。生物质对炼焦生产的实用性研究如下:将1%～5%的木质生物质或是焙烤(轻度热解)的木质生物质作为部分高挥发性煤的替代物添加至配合煤中,在实验室焦炉中进行碳化试验。试验结果表明,当把粉碎的生物质加入到配合煤后,焦化压力显著降低,同时焦炭的硫含量下降,但是焦炭的高温强度和力学性能亦有轻微下降,但这种实测强度的降低需要进一步的研究。另外,在一系列独立试验中,通过利用生物质(分别是锯末、粉碎的玉米芯、树皮、木炭等)作为烧结用粉焦的替代燃料在实验室烧结锅进行评估。试验中,燃料用10%、20%、30%、40%的生物质代替。试验结果显示,烧结混合料的堆密度和烧结时间都有下降,添加了生物质的烧结矿质量没有显著恶化。这些初步的试验表明,在实际的炼焦与炼铁生产中生物质很有可能作为一种可再生能源替代部分传统的化石燃料。为了某种特定应用而进行产品优化则需要额外试验。     

连铸生产中过程参数对夹杂物分离和分布的影响

作为连铸机中一个重要的设备,中间包是连接非连续的钢包冶炼和连续的结晶器中铸坯凝固的连接设备。中间包在生产超纯净钢过程中承担着重要角色,其主要目的是尽可能细化各钢种的夹杂物并提高钢水纯净度,尤其是当钢包更换而导致进入中间包钢水条件改变时。夹杂物会影响后续压力加工过程,且经常导致材质性能失效。钢水的纯净度对满足客户性能要求起着至关重要的作用。采用比例为1:3的单流中间包水模研究了不锈钢中夹杂物的去除。水模中的浸入式水口上配备有一个粒子计数器,此计数器可以计算出直径大于25μm的粒子分离率。由于粒度分布的相似性,水模中的粒子沉积速率可以转换到实际中间包中的熔体流动。对流动改变装置(例如冲击板)的影响进行了研究,同样也研究了有无冲击板条件下的不同尺寸粒子在中间包的粒子分布状态。采用雷诺应力湍流模型,应用有限体积商业软件FLUENT,进行了数值模拟。离散相的建模采用欧拉-拉格朗日方法。表面处颗粒分离采用一种特殊的边界条件。     

Microstructure and Mechanical Properties of Friction Stir Lap Welded Aluminum Alloy AA2014

Friction stir lap welds were produced in 3 mm thick Alclad sheets of Al alloy 2014-T4 using two different tools (with triangular and threaded taper cylindrical pins). The effects of tool geometry on weld microstructure, lap-shear performance and failure mode were investigated. The pin profile was found to significantly influence the hook geometry, which in turn strongly influenced the joint strength and the failure mode. Welds produced in alloy 2014-T4 Alclad sheets by using triangular and threaded taper cylindrical tools exhibited an average lap-shear failure load of 16.5 and 19.5 kN, respectively, while the average failure load for standard riveted joints was only 3.4 kN. Welds produced in alloy 2014-T6 Alclad sheets and in alloy 2014-T4 bare sheets (i.e., no Alclad) were comparatively evaluated with those produced in alloy 2014-T4 Alclad sheets. While the welds made (with threaded taper cylindrical tool) in T6 and T4 conditions showed very similar lap-shear failure loads, the joint efficiency of the welds made in T6 condition (43%) was considerably lower (because of the higher base material strength) than those made in T4 condition (51%). The Alclad layers were found to present no special problems in friction stir lap welding. Welds made with triangular tool in alloy 2014-T4 Alclad and bare sheets showed very similar lap-shear failure loads. The present work provides some useful insights into the use of friction stir welding for joining Al alloys in lap configuration.     

Flat Absorber Phosphorous Black Nickel Coatings for Space Applications

A new process of flat absorber black nickel alloy coating was developed on stainless steel by electrodeposition from a bath containing nickel,zinc and ammonium sulphates;thiocyanate and sodium hypophosphite for space applications.Coating process was optimized by investigating the effects of plating parameters,viz concentration of bath constituents,current density,temperature,pH and plating time on the optical properties of the black deposits.Energy dispersive X-ray spectroscopy showed the inclusion of about 6% phosphorous in the coating.The scanning electron microscopy studies revealed the amorphous nature of the coating.The corrosion resistance of the coatings was evaluated by the electrochemical impedance spectroscopy (EIS) and linear polarization (LP) techniques.The results revealed that,phosphorous addition confers better corrosion resistance in comparison to conventional black nickel coatings.The black nickel coating obtained from hypophosphite bath provides high solar absorptance (α s) and infrared emittance (ε IR) of the order of 0.93.Environmental stability to space applications was established by the humidity and thermal cycling tests.     

Quantitative imaging of red blood cell velocity invivo using optical coherence Doppler tomography

We present particle counting ultrahigh-resolution optical Doppler tomography (pc-μODT) that enables accurate imaging of red blood cell velocities (ν(RBC)) of cerebrovascular networks by detecting the Doppler phase transients induced by the passage of a RBC through a capillary. We apply pc-μODT to image the response of capillary ν(RBC) to mild hypercapnia in mouse cortex. The results show that ν(RBC) in normocapnia (ν(N)?=?0.72?±?0.15?mm/s) increased 36.1%?±?5.3% (ν(H)?=?0.98?±?0.29?mm/s) in response to hypercapnia. Due to uncorrected angle effect and low hematocrit (e.g., ～10%), ν(RBC) directly measured by μODT were markedly underestimated (ν(N) ≈ 0.27?±?0.03?mm/s, ν(H) ≈ 0.37±?0.05?mm/s). Nevertheless, the measured ν(RBC) increase (35.3%) matched that (36.1%?±?5.3%) by pc-μODT.