(111)-Oriented BaTiO3 thin films hydrothermally formed on TiO2/Si substrate

Abstract

Barium titanate (BaTiO₃) thin films with high (111)-orientation were successfully grown on TiO₂-covered Si(111) substrate using hydrothermal method, where the TiO₂ layer was previously fabricated at room temperature by means of ion-beam-assisted deposition. This processing method provides a simple mild-chemical route for directly producing the analogous crystalline films on different substrates. The BaTiO₃ films did not reach the TiO₂/Si interface even if the hydrothermal treatment was prolonged to 24 hours. Both Rutherford backscattering and spread-resistance profiling characterizations confirmed the diffusion nature of the formed Ba-TiO₃/TiO₂/Si system.     

靠模式弯箍机构设计与转角数模修正

为提高钢筋任意角度(-180.～180.)连续自动弯曲成形精度和效率,引入靠模成形设计方法,提出了一种新型箍筋模钢筋弯箍设计方案.基于弹复理论,建立了钢筋弯曲过程中弯箍转盘转角与钢筋弯曲成形角度之间的函数关系式.运用ANSYS/LS-DYNA非线性有限元分析软件建立了弯箍系统的有限元模型,验证了弯箍转盘转角与箍筋角度之间的数学模型的精确性,基于对钢筋不同成形角度的回弹角度模拟,对转盘转角数模进行了修正.结果表明,该机构设计合理,满足柔性生产要求,便于实现高精度成形自动控制.     

Growth and characterization of (Pb,La)(Zr,Ti)O3 thin film epilayers on SrTiO3-buffered Si(001)

Ferroelectric Pb_0.92La_0.08Zr_0.4Ti_0.6O₃ (PLZT) thin films were deposited on SrTiO₃-buffered Si(001) substrate by on-axis radio frequency magnetron sputtering. X-ray diffraction analysis revealed epitaxial growth of monocrystalline PLZT films, with an (001) rocking curve full width at half maximum of ∼ 0.3°. φ-scans showed 45° in-plane orientation of the perovskite unit cell relative to that of silicon. The elemental composition of the thin film heterostructure was examined by Auger sputter depth profiling measurements. The recorded profiles suggest that the SrTiO₃ buffer layer serves not only as a template for epitaxial growth, but also as a barrier suppressing Pb-Si interdiffusion between the PLZT layer and the Si substrate. The surface roughness of the PLZT layer was measured at ∼ 4 nm for films with ∼ 500 nm thickness. Wavelength dispersions for the refractive index (n) and the extinction coefficient (k) were obtained from spectroscopic ellipsometry measurements, with n ∼ 2.48 at the main communication wavelength λ = 1550 nm and k < 0.001 for λ > 650 nm. Recorded polarization vs. electric field loops for the PLZT epilayer, with a SrRuO₃ electrode layer interposed between PLZT and SrTiO₃, showed a remnant polarization P_r ≈ 40 µC/cm² and coercive field E_c ≈ 100 kV/cm. These findings suggest that the sputter-deposited PLZT thin films retain the functional properties critical to ferroelectric and electro-optic device applications, also when integrated on a semiconductor substrate.     

Evaluation of the depth resolutions of Auger electron spectroscopic, X-ray photoelectron spectroscopic and time-of-flight secondary-ion mass spectrometric sputter depth profiling techniques

Concentration-depth profiles of sputter-deposited Si/Al multilayered specimens were determined by model fitting to measured data obtained by depth profiling, using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectrometry (TOF-SIMS). The model used for calculation of the concentration-depth profile accounts for the broadening (“smearing”) upon experimental depth profiling owing to the effects of atomic mixing, preferential sputtering, surface roughness and information depth of either the Auger electrons (for AES depth profiling) or the photoelectrons (for XPS depth profiling) or the secondary ions (for SIMS depth profiling). The depth resolution for each technique was derived directly from the values determined for the fitting parameters in the model.     

Micro-fabrication techniques applied to aluminosilicate glass surfaces: Micro-indentation and wet etching process

Micro-indentation and HF etching were explored as micro-fabrication techniques applied to glass surfaces. The effects of the aluminosilicate glass composition and of the etching conditions on the etching rate were investigated. It was found that the etching rate increased with increasing the ratio of Al₂O₃ to SiO₂ in the aluminosilicate glass. Etching parameters, such as pH, concentration and temperature of HF acid, had effects on etching rate. However, the effects of these parameters were much smaller at indented area than at non-indented area. The results indicated that the etching rate difference between the two areas, which is one of the key factors in the micro-fabrication technique, could be controlled with these parameters. And the phenomena can be well explained in terms of etching and leaching mechanism of aluminosilicate glass.     

Microbial source tracking using host specific FAME profiles of fecal coliforms

The objective of this study was to investigate the host-specific differences in fatty acid methyl ester (FAME) profiles of fecal coliforms (FC). A known-source library was constructed with 314 FC isolates cultured from 6 possible sources of fecal pollution; 99 isolates from sewage; 29 from bovine; 29 from poultry; 50 from swine; 46 from waterfowl; and 61 from deer. It was found that the hydroxy FAMEs 12:0 2 OH, 12:03 OH, and 14:02 OH were exclusively associated with isolates of human origin. On the other hand, 3 saturated FAMEs, 10:0, 15:0, and 18:0 were found only in isolates from non-human sources, 15:0 being associated with livestock samples only. In addition to the presence of these signature FAMEs, the mean relative masses of 16:1 omega7c and 16:1 ISO/14:03 OH were significantly different between the isolates of human and non-human origins. A linear discriminant function differentiated FC isolates of human origin from those of livestock and wildlife origin at 99% accuracy. These results strongly suggest that the FAME profiles of FC show statistically significant host specificity and may have the potential to be used as a phenotypic microbial source tracking tool.     

PLC靠模卷簧机系统的研制

针对进口卷簧机价格较贵,维修困难等问题,采用PLCF1-60MR进行现场测控、机械手操作、靠模卷簧的先进模式,研制了一种新型卷簧机控制系统,并给出了本系统设计方法．实际运行表明,该系统的整体性能和自动化水平得以大幅度提高,满足了该行业的市场需求．     

热蛋白质组学分析鉴定TH588的靶标蛋白

通过对活性小分子靶标蛋白的鉴定,可以建立活性小分子与细胞表型之间的联系,阐明活性小分子的功能和作用机理,对小分子药物的研发具有重要意义.热蛋白组学分析(thermal proteome profi-ling,TPP)是基于蛋白-配体结合可以增加蛋白热稳定性这一原理发展的鉴定活性小分子靶标蛋白的新技术,相较于其他小分子靶...     

Healthy Snacks: Using Nutrient Profiling to Evaluate the Nutrient‐Density of Common Snacks in the United States

Objective: To quantify and compare the nutrient‐density of commonly consumed snacks using two nutrient‐density measures, Nutrient Rich Foods Indices 9.3 (NRF 9.3) and 15.3 (NRF 15.3). Design: Identify commonly consumed categories of snacks and individual snack foods, calculate NRF 9.3 and 15.3 scores, rank snacks by category and by individual food based on nutrient density, compare and contrast scores generated by the two NRF Indices. Main Outcome Measures: NRF 9.3 and 15.3 scores. Analysis: Averages and standard deviations of nutrient‐density scores for each snack category. Results: Vegetables and coffee/tea received the highest category scores on both indices. Cakes/cookies/pastries and sweets had the lowest category scores. NRF 9.3 scores for individual snacks ranged from –46 (soda) to 524 (coffee). NRF 15.3 scores ranged from –45 (soda) to 736 (coffee). Conclusions and Implications: If added to food labels, NRF scores could help consumers identify more nutritious choices. The differences between NRF 9.3 and 15.3 scores generated for the same foods and the limitations of these indices highlight the need for careful consideration of which nutrient‐density measure to include on food labels as well as consumer education.