以L-酒石酸正己酯-硼酸配合物为反相液相色谱手性流动相添加剂分离班布特罗和妥洛特罗

以L-酒石酸正己酯-硼酸配合物为流动相添加剂,采用反相高效液相色谱法分离了班布特罗和妥洛特罗2种手性β-受体激动剂。实验考察了酒石酸正己酯和硼酸的浓度,缓冲溶液的种类、浓度、pH值,有机改性剂甲醇的含量对手性分离效果的影响。在最佳手性分离条件下,班布特罗和妥洛特罗均可以达到基线分离。     

瞬态瑞利波法对液化地基强夯加固效果评价与测试

本文针对某机场地基的特殊性 ,采用强夯对地基进行抗液化加固处理 ,并根据瞬态瑞利波法的原理和特点 ,研究利用瞬态瑞利波方法对土层液化势进行评价 ,从试验的结果来看 ,瞬态瑞利波法对强夯消除土层液化效果评价具有可靠、简捷、经济等优点     

Broadband Microwave Measurements of Overdoped Y0.9Ca0.1Ba2Cu3O7−δ Films Using Corbino Geometry

The surface impedance of Y_0.9Ca_0.1Ba₂Cu₃O_7?δ thin films was measured using the Corbino spectroscopy method. This special geometry, in which the sample dimensions are well defined by a ring pattern, is ideal for broadband high frequency reflection measurements. Using the complex reflected signal, S ₁₁, measured by a vector network analyzer, one can find the surface impedance of the thin film, from which the complex conductivity can be deduced. In the current work we present the three-standard approach for calibration of the Corbino method and demonstrate the benefits of this approach in measuring superconducting Y_0.9Ca_0.1Ba₂Cu₃O_7?δ thin films up to 20 GHz and down to 6 K. For the data analysis the well-known generalized two-fluid model was implemented, taking into account a film thickness which is much smaller than the normal state skin depth and superconducting penetration depth.     

Tribological impact of touchdown detection on bit patterned media robustness

Touchdown detection by thermal-flying height control (TFC) has been implemented to calibrate flying height (FH) of magnetic sliders for all hard disk drives. For bit patterned media (BPM) to be successful as a revolutionary technology to further increase recording areal density, it must experience the touchdown process with similar robustness as conventional continuous media. Here we numerically study the tribological impact of TFC touchdown detection on the continuous media and unplanarized BPM by three-dimensional (3D) transient finite-element models with the frictional heating and thermal-elastic-plastic materials included. Our results demonstrate that the continuous media exhibits no plastic deformation due to the TFC touchdown with an over-push as large as 2 nm, whereas the plastic strain of the BPM may reach 3 % at higher sliding velocities, and it exists over a wide range of bulge radius and disk velocity. Such plastic deformation can lead to permanent media damage and data loss. Besides, the temperature rise of the BPM (~27 K) is approximately 1.3 times of that of the continuous media (~21 K), and may have to be considered when designing a robust head-disk interface for BPM. Although planarization may improve slider’s flyability performance, our analysis shows that planarizing BPM with SiO₂ deteriorates the tribological robustness of the media in particular at a high disk velocity probably due to the inhomogeneous composition and mismatch of material properties between the filling material and recording material. Hence extreme caution must be exercised when choosing a filling material.     

Lower-error and area-efficient antilogarithmic converters with bit-correction schemes

In this article, we have proposed fast lower-error and area-efficient antilogarithmic converters. By employing new approximation schemes with two-region shift-and-add operations, our proposed converters can perform high-speed conversions from logarithmic numbers to binary numbers. Synthesis results show that our proposed converters can achieve time savings of over 32.5% and can save 42.3% of the area used compared with previously proposed methods. In addition, the percent error ranges for various logarithmic number system (LNS)-based operations used by our proposed logarithmic processor are lower than those of previous methods. Our proposed converters can be applied to LNS-based processors to ease the tremendous computation overhead and boost the performance.     

A computational algorithm for catalysts experiencing concentration‐dependent deactivation

Abstract

A computational algorithm is proposed for catalyst pellets or reactors experiencing concentration‐dependent deactivation. In the integration of the deactivation equation in each time interval, the concentration of poison, reactant or/and product is considered to be a constant. The value of concentration is recalculated from the mass balance equation before integrating the deactivation equation. By such an approach, the number of equations is reduced; thus a two‐dimensional problem can be converted to a single‐dimensional one.     

Family, school, and neighborhood: Links to Chinese American adolescent perceptions of racial/ethnic discrimination.

The purpose of the study was to examine how family, school, and neighborhood factors contributed to Chinese American adolescent perceptions of discrimination. The sample included 185 Chinese American adolescents (mean age = 16.8 years, SD = .81; 58% female; 70% U.S.-born) and their parents. As hypothesized, the results showed that greater parent perceptions of discrimination, more negative school environment, and less availability of cultural resources were related to greater adolescent perceptions of discrimination. Contrary to the hypothesis, parent/adolescent subjective perceptions of ethnic density were related to greater adolescent perceptions of discrimination. The findings suggest that adolescent perceptions of discrimination are related to both within and outside family factors, supporting an ecological approach to understanding racial/ethnic discrimination. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Submicron-meter tunneling field-effect poly-Si thin-film transistors with a thinned channel layer

Submicron-meter poly-Si tunneling-effect thin-film transistor (TFT) devices with a thinned channel layer have been investigated. With reducing the gate length to be shorter than 1 μm, the poly-Si TFT device with conventional MOSFET structure is considerably degraded. The tunneling field-effect transistor (TFET) structure can be employed to alleviate the short channel effect, thus largely suppressing the off-state leakage. However, for a poly-Si channel layer of 100 nm thickness, the TFET structure causes a small on-state current, which may not provide well sufficient driving current. By reducing the channel layer thickness to be 20 nm, the on-state current for the TFET structure can be largely increased, due to the enhanced bending of energy band for a thinned channel layer. As a result, for the TFET poly-Si TFTs at a gate bias of 5 V and a drain bias of 3 V, a 20-nm channel layer leads to an on-state current of about 1 order larger than that by a 100-nm channel layer, while still keeping an off-state leakage smaller than 0.1 pA/μm. Accordingly, the submicron-meter TFET poly-Si TFT devices with a thinned channel layer would show good feasibility for implementing high packing density of poly-Si TFT devices.     

Transient Characteristics of Nanoscale Air Bearings Subjected to Joule Heating

Transient characteristic of heat exchange between closely positioned bodies has become an important issue owing to the continuous miniaturization of many technologies such as high-density magnetic recording, integrated circuits, and atomic force microscopy. We experimentally and numerically study the transient characteristics of nanoscale air bearings subjected to Joule heating of a nearby heating element in hard disk drives. Our results reveal that the response consists of multiple characteristic times, and at least two terms (τ ₁ = 162 μs and τ ₂ = 23 μs) are required to capture the transient response. We present a one-dimensional analytical model that provides a better understanding of the nature of the transient characteristics and an efficient way to obtain their trends and bounds. Our model may also explain the much faster response due to laser heating observed in heat-assisted magnetic recording system.