ENHANCEMENT EFFECT OF PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED SIN CAPPING LAYER ON DIELECTRIC CAP QUANTUM-WELL DISORDERING

Quantum well disordering of GaAs/AlGaAs multiple quantum well(MQW) has been accomplished with only plasma enhanced chemical vapor deposited (PECVD) SiN cap layer growth. The amount of blue shift increases with SiN growing time. This result has been explained by the vacancy indiffusion during PECVD SiN growth. Rapid thermal annealing (RTA) of the sample after SiN cap layer growth at 850 degrees C for 35 s caused a larger amount of blue shift than those obtained without RTA. By considering the model of Al diffusion from AlGaAs barrier into GaAs QWs together with the result from photoluminescence (PL) measurement, Al diffusion coefficients were calculated. The Al diffusion coefficient due to PECVD SiN was estimated at about 3 x10(-17) cm(2)/s. It was possible to extract the effect of RTA on the QW disordering, which showed that the amount of the blue shift and the Al diffusion coefficient due only to RTA increases with SiN cap layer thickness as reported by Chi et al.(10))

SiN薄膜三阶非线性增强的研究

采用射频磁控反应溅射法结合热退火处理技术制备纳米硅镶嵌氮化硅(ncSi-SiN_x)复合薄膜.通过X射线能谱(EDS)、X射线衍射仪(XRD)的测定,对薄膜进行了结构及所包含硅晶粒大小的表征.采用皮秒激光器运用单光束Z扫描技术开展了对该复合薄膜的非线性光学性质的研究,测得其三阶非线性折射率系数和非线性光吸收系数分别为10~(-8) esu和10~(-8)m/W量级,并将薄膜这种三阶光学非线性的增强归因于量子限域效应.

SIN~+GaAs结构中的Franz-Keldysh振荡的傅里叶变换研究

利用傅里叶变换(FT)方法，对Franz-Keldysh振荡(FKO)的理论线性作了详细的数值模拟，并用光调制反射谱(PR)测量了一组本征层(I层)厚度不同的表面-本征层n-型重掺杂层(SIN~+)结构的GaAs样品的FKO.PR谱的FT分析表明，一部分样品的FT谱，包括其实部、虚部和模，与理论线性符合得比较好，由此求出轻空空(LH)和重空穴(HH)的约化质量平方根之比μ_1~(1/2)/(μ_h)~(1/2)对不同样品在0.805-0.816之间，同时也可以求出样品中的内建电场强度F_1，和调制光引起的调制电场δF=F_1-F_2。有一些样品的FT谱实部和虚部与理论线性差别很大，用FT的模仍可以给出有用的信息。

Evidence for perimeter sites over SmOx-modified Rh(100) surface by CO chemisorption

SmOx modified Rh(l 0 0) surfaces have been in-situ prepared by depositing metallic Sin and subsequently oxidizing under controlled conditions, and the interaction between the lanthanide oxide and transition metal has been characterized by means of X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy (HREELS) as well as thermal desorption spectroscopy (TDS). As evidenced, the adsorption of CO on the modified surfaces shows some different features to the original surface of Rh(l 00). The covering of SmOx blocks some sites on the surface and consequently suppresses adsorption of the typical CO species with an uptake at about 500 K, while a novel desorption peak centered at 260 K emerges in the CO TDS. Correspondingly, the XP spectrum exhibits a new C Is peak at 287.9 eV and 0 Is peak at 532.6 eV. The intensity of the low temperature peak varies with the coverage of SmOx, which shows an actual correlation to the perimeter sites of SmOx particles on the surface. (C) 2004 Elsevier B.V. All rights reserved.

Thermal, mechanical and ionic conductive behaviour of gamma-radiation induced PEO/PVDF(SIN)-LiClO4 polymer electrolyte system

An effort has been made to modify the mechanical behaviour of our previously reported gel-type gamma-radiation crosslinked polyethylene oxide (PEO)-LiClO4 polymer electrolyte. A highly polar and gamma-radiation crosslinkable crystalline polymer, polyvinylidene fluoride (PVDF), was selected to blend with PEO and then subjected to gamma-irradiation in order to make an simultaneous interpenetrating network (SIN), which was used as a polymer host to impart stiffness to the plasticized system. Experimental results have shown that the presence of PVDF in the system, through gamma-radiation induced SIN formation, could not only give a rather high mechanical modulus of 10(7) Pa at ambient temperature, but also maintain the room temperature ionic conductivity at a high level (greater than 10(-4) S/cm). DSC, DMA and conductivity measurement techniques were used to examine the effects of blending, gamma-irradiation and plasticization on the variations of glass transition and melting endotherm, on the appearance of high elastic plateau and on the temperature dependence of ionic conductivity: In addition, it was found that, in contrast with the unplasticized system, the ionic conductivity mechanism of this gel-type electrolyte seems to conform to the Arrhenius model, suggesting that, as a result of the high degree of plasticization, the polymer chains act mainly as the skeleton of the networks or polymer cages to immobilize the liquid electrolyte solution, whereas the ionic species migrate as if they were in a liquid medium. (C) 1997 Elsevier Science Ltd.

Limits of ventricular function: from athlete's heart to a failing heart

The interest in the study of ventricular function has grown considerably in the last decades. In this review, we analyse the extreme values of ventricular function as obtained with Doppler echocardiography. We mainly focus on the parameters that have been used throughout the history of Doppler echocardiography to assess left ventricular (LV) systolic and diastolic function. The ‘athlete's heart’ would be the highest expression of ventricular function whereas its lowest expression is represented by the failing heart, independently from the original aetiology leading to this condition. There are, however, morphological similarities (dilation and hypertrophy) between the athlete's and the failing heart, which emerge as physiological and pathophysiological adaptations, respectively. The introduction of new assessment techniques, specifically speckle tracking, may provide new insight into the properties that determine ventricular filling, specifically left ventricular twisting. The concept of ventricular function must be always considered, although it may not be always possible to distinguish the normal heart of sedentary individuals from that of highly trained hearts based solely on echocardiographic or basic studies.

Comentarios de la Guerra de España, e historia de su rey Phelipe V el Animoso, desde el principio de su reynado, hasta la Paz General del año de 1725 : dividido en dos tomos

[Vá esta impression cotejada con el original del Autor, y corregida de los innumerables errores que padecen las otras].

Asesoría en diseño.

106 hojas : ilustraciones.

Programa Nacional de Joyería. Asesoría en Diseño. Bogotá, 2001 - 2002.

113 hojas : ilustraciones.

Programa Nacional de Joyería. Taller de Diseño, Departamento de Antioquia municipios de Frontino y Santa Fe de Antioquia febrero 19 a marzo 17 de 2002.

107 hojas : Ilustraciones.

Muestras de productos con y sin esmaltado, elaborados en Guatavita.

19 hojas : ilustraciones, fotografías

Muestras de adecuación y uso de fibras naturales y una técnica de tinturado por inmersión en lodo de la etnia Sinú en Sucre y Cordoba.

33 fotografías a color.

A reconsideration of the theological conception of sin in the light of the psychoanalytic conceptions of shame and guilt

Boston University Graduate School of Arts and Sciences. Department of Religion.

Investigation of micro-devices for neurobiological applications

The aim of this project is to integrate neuronal cell culture with commercial or in-house built micro-electrode arrays and MEMS devices. The resulting device is intended to support neuronal cell culture on its surface, expose specific portions of a neuronal population to different environments using microfluidic gradients and stimulate/record neuronal electrical activity using micro-electrode arrays. Additionally, through integration of chemical surface patterning, such device can be used to build neuronal cell networks of specific size, conformation and composition. The design of this device takes inspiration from the nervous system because its development and regeneration are heavily influenced by surface chemistry and fluidic gradients. Hence, this device is intended to be a step forward in neuroscience research because it utilizes similar concepts to those found in nature. The large part of this research revolved around solving technical issues associated with integration of biology, surface chemistry, electrophysiology and microfluidics. Commercially available microelectrode arrays (MEAs) are mechanically and chemically brittle making them unsuitable for certain surface modification and micro-fluidic integration techniques described in the literature. In order to successfully integrate all the aspects into one device, some techniques were heavily modified to ensure that their effects on MEA were minimal. In terms of experimental work, this thesis consists of 3 parts. The first part dealt with characterization and optimization of surface patterning and micro-fluidic perfusion. Through extensive image analysis, the optimal conditions required for micro-contact printing and micro-fluidic perfusion were determined. The second part used a number of optimized techniques and successfully applied these to culturing patterned neural cells on a range of substrates including: Pyrex, cyclo-olefin and SiN coated Pyrex. The second part also described culturing neurons on MEAs and recording electrophysiological activity. The third part of the thesis described integration of MEAs with patterned neuronal culture and microfluidic devices. Although integration of all methodologies proved difficult, a large amount of data relating to biocompatibility, neuronal patterning, electrophysiology and integration was collected. Original solutions were successfully applied to solve a number of issues relating to consistency of micro printing and microfluidic integration leading to successful integration of techniques and device components.