Mechanisms for the formation of low temperature,non-alloyed Au-Ge ohmic contacts to n-GaAs

Low temperature, non-alloyed Au-Ge contact formation ton-GaAs is a multi-step pro-cess. During the first 5 min of annealing at 320° C the Au and Ge segregate into regions a few microns in size and extend over the entire thickness of the metal layer and sig-nificant in-diffusion of the Au and Ge and out-diffusion of the Ga and As occurs. This intermixing reduces the barrier height from 0.75 to 0.40 eV. The contact does not show ohmic behavior until it has been annealed for 3 hr. During this time Ge continues to in-diffuse but at a slower rate than it did initially. The rate of Ge in-diffusion is en-hanced by the presence of Au since samples containing less Au require longer anneals to show ohmic behavior and have higher specific contact resistances. The presence of excess As, which is prevented from evaporating by a Si₃N₄ cap has the opposite effect since capped layers have higher specific contact resistances. Au-Ge phases appear after approximately 3 hr of annealing, therefore, Au-Ge phases cannot be responsible for the reduction in barrier height. The interface morphology is smooth, differing from that of pure Au and alloyed contacts that often contain spiking of the metals into the semi-conductor. The orientation relationship for the Au grains differs from that of pure Au. Work performedat U.S. Army ETDL, Fort Monmouth, NJ 07703. Work performed at U.S.Army ETDL, Fort Monmouth, NJ 07703.     

Characterisation and Assessment of the Role of Barley Malt Endoproteases During Malting and Mashing1

Barley malt endoproteases (EC.3.4.21) develop as multiple isoforms mainly during grain germination and pass through kilning almost intact. Thermostability, under simulated mashing conditions, varied from low to high depending on the substrate used in the assay. This suggests that individual enzymes respond differently to heat exposure and to protein substrates. The optimal pH with haemoglobin was pH 3.5, with hordein pH 4 and with glutelin pH 5. The optimal temperature with hordein was 40°C, with glutelin 50°C and with haemoglobin 60°C. These differences suggest that it is not possible to comprehensively characterise all malt endoproteases under one set of assay conditions. In brewing, most of the barley protein degradation (> 70 %) occurs during malting. But some proteinases remain active during mashing and contribute to wort soluble proteins and free amino nitrogen. Their contribution to all malt EBC mash total free amino nitrogen was 25 % in Schooner (Australian) and 30 % in Morex (USA). The importance of proteolytic activity during mashing and the possibility that the levels may not be adequate, at high solid adjunct ratios, are acknowledged.     

Free radical chemistry of disinfection byproducts. 2. Rate constants and degradation mechanisms of trichloronitromethane (chloropicrin)

Absolute rate constants for the free-radical-induced degradation of trichloronitromethane (TCNM, chloropicrin) were determined using electron pulse radiolysis and transient absorption spectroscopy. Rate constants for hydroxyl radical, *OH, and hydrated electron, e(aq)-, reactions were (4.97 +/- 0.28) x 10(7) M(-1) s(-1) and (2.13 +/- 0.03) x 10(10) M(-1) s(-1), respectively. It appears that the *OH adds to the nitro-group, while the e(aq)- reacts via dissociative electron attachment to give two carbon centered radicals. The mechanisms of these free radical reactions with TCNM were investigated, using 60Co gamma irradiation at various absorbed doses, measuring the disappearance of TCNM and the appearance of the product nitrate and chloride ions. The rate constants and mechanistic data were combined in a kinetic computer model that was used to describe the major free radical pathways for the destruction of TCNM in solution. These data are applicable to other advanced oxidation/reduction processes.     

Effects of Physically Adsorbed Films on Conductivity of?Two-Dimensional Metal Surfaces and Graphene

The electronic properties of two-dimensional (2D) materials, like graphene, are of considerable fundamental interest. This paper describes how physically adsorbed films probe these properties. The cases of an ideal 2D free electron gas and graphene are examined, with explicit results found for an adsorbed He film. In the free electron case, the scattering is proportional to the 2D structure factor of the film. Results are presented for He on graphene and the free electron gas in both the low coverage and fully commensurate limits.     

Global fault localization using induced voltage alteration

Advances in integrated circuit technology have made failure site localization extremely challenging. Charge-induced voltage alteration (CIVA), low energy CIVA (LECIVA), light-induced voltage alteration (LIVA), Seebeck effect imaging (SEI) and thermally-induced voltage alteration (TIVA) are five recently developed failure analysis techniques which meet the challenge by rapidly and non-destructively localizing interconnection defects on ICs. The techniques take advantage of voltage fluctuations in a constant current power supply as an electron or photon beam is scanned across an IC. CIVA and LECIVA are scanning electron microscopy techniques that yield rapid localization of open interconnections. LIVA is a scanning optical microscopy (SOM) method that yields quick identification of damaged semiconductor junctions and determines transistor logic states. SEI and TIVA are SOM techniques that rapidly localize open interconnections and shorts respectively. LIVA, SEI, and TIVA can be performed from the backside of ICs by using the proper photon wavelength. This paper describes the CIVA, LECIVA, LIVA, TIVA, and SEI techniques in terms of the physics of signal generation, general data acquisition system required, and imaging results displaying the utility of each technique for localizing interconnection defects.     

Dietary supplement increases plasma norepinephrine, lipolysis, and metabolic rate in resistance trained men

Correction to Richard J Bloomer, Kelsey H Fisher-Wellman, Kelley G Hammond, Brian K Schilling, Adrianna A Weber and Bradford J Cole: Dietary supplement increases plasma norepinephrine, lipolysis, and metabolic rate in resistance trained men. Journal of the International Society of Sports Nutrition 2009, 6: 4     

Adaptive statistical scheduling of divisible workloads in heterogeneous systems

This article presents a statistical approach to the scheduling of divisible workloads. Structured as a task farm with different scheduling modes including adaptive single and multi-round scheduling, this novel divisible load theory approach comprises two phases, calibration and execution, which dynamically adapt the installment size and number. It introduces the concept of a generic installment factor based on the statistical dispersion of the calibration times of the participating nodes, which allows automatic determination of the number and size of the workload installments. Initially, the calibration ranks processors according to their fitness and determines an installment factor based on how different their execution times are. Subsequently, the execution iteratively distributes the workload according to the processor fitness, which is continuously re-assessed throughout the program execution. Programmed as an adaptive algorithmic skeleton, our task farm has been successfully evaluated for single-round scheduling and generic multi-round scheduling using a computational biology parameter-sweep in a non-dedicated multi-cluster system.     

Instrumentation for space

The primary drivers for space instruments are the environment and survivability, support assets, delivery cost, and lack of accessibility. Survivability deals primarily with environments, such as launch and depressurization, extremes of temperature, high vacuum, radiation, and hypervelocity impacts. The cost to deployment is directly coupled to launch services, which are inherently expensive. These costs are nonlinear functions of the mass and volume of satellite payloads. The “user interfaces” for space-borne instruments are high-cost assets because they include mission operations centers, satellite hacking station(s), and ground networks. All of these issues demand high reliability     

Malting for Brewhouse Performance*

In many instances brewhouse performance cannot be predicted from a finished malt specification. This is particularly so for factors such as lautering, yeast performance, filtration and head character. There are two aspects involved in improving the brewing performance of malt. Firstly, an understanding of the malt characteristics affecting particular aspects of the brewing process and secondly an understanding of how the malting process affects or can be controlled to optimise these characteristics and thus their performance. In this work the relationship between barley variety, steeping pattern, malt quality and brewing performance is investigated. Six different barley varieties were micromalted in a Seeger micromalting unit under four different steeping regimes. Sub-samples were taken at intervals during steeping for enzyme analysis and measurement of water distribution. Following steeping, the samples were germinated and kilned using standard micromalting conditions. Finished malts were analysed by standard EBC methods for routine malt quality parameters including apparent attenuation limit. Worts were tested for total β-glucan content, β-glucan molecular weight distribution, filter plugging potential and carbohydrate levels. A sub set of malt samples were then micro-brewed and tested for β-glucan molecular weight (MW) distribution, beer filterability and foam stability.