Analysis of Current–Voltage Measurements on Long-Wavelength HgCdTe Photodiodes Fabricated on Si Composite Substrates

We have performed a detailed study of dark current versus voltage to understand existing limitations in dark current and address the nonuniformity of dark current in devices fabricated on HgCdTe grown on silicon substrates. One interesting observation is that trap-assisted tunneling, g-r currents, are not found close to zero bias in certain devices. Devices from the low end of the R ₀ A distribution show heavy shunting paths close to zero bias. We believe that these shunting paths may be the limiting cause of tail distributions in fabricated focal plane array tail distributions. Possible causes for these shunting paths are surface charges associated with dislocation cores and impurity gettering at dislocation cores. The measured non-anti-reflection (AR)-coated quantum efficiency (QE) was 0.576 at 78 K and displays the classical response versus wavelength. The measured QE on isolated single devices is consistent with the 256 × 256 focal-plane array mean QE. Obtained average dark currents are on the order of mid 10⁻⁵ A cm^–2, which is one order of magnitude higher than dark currents obtained from arrays on lattice-matched substrates. On average, arrays on lattice-mismatched substrates show performance characteristics inferior to those of arrays fabricated on lattice-matched substrates. This inferior performance is due to array pixel operability, as can be seen from the tail of the distribution and the average dark currents, which are one order of magnitude higher than those obtained on lattice-matched substrates.     

Flocculation,cell surface hydrophobicity and 3‐OH oxylipins in the SMA strain of Saccharomyces pastorianus

Three‐hydroxy‐oxylipins (3‐OH oxylipins) have been previously detected in brewing yeast production strains at flocculation onset. In this work, the SMA strain of Saccharomyces pastorianus was characterized during growth in a miniature fermentation assay by measuring flocculation and cell surface hydrophobicity (CSH). Proportions of 3‐OH oxylipin were also measured concurrently during growth in the miniature fermentation assay and a defined 3‐OH oxylipin extraction protocol using ethyl acetate is presented along with a novel derivatization and gas chromatography–mass spectrometry (GC‐MS) detection approach. When the SMA strain was grown in the assay, near maximal CSH and flocculation levels were achieved by a 36 h fermentation time. Under the same culture conditions, the oxylipin 3‐OH decanoic acid (3‐OH 10:0) was identified. This oxylipin could not be detected early in the fermentation, but elevated relative levels of 3‐OH 10:0 were reached by 36 h, coinciding with increased CSH levels. It was previously presumed that the formation of 3‐OH oxylipins at flocculation onset might increase the CSH. However, results from this study suggest that 3‐OH 10:0 may not contribute to cell wall hydrophobicity. The flocculation behaviour of the SMA strain was also monitored in the presence of 3‐OH 10:0, but exposure to this oxylipin did not impact the sedimentation of this yeast, suggesting that 3‐OH oxylipins may not act as mediators of quorum sensing in this strain. Copyright © 2015 The Institute of Brewing & Distilling     

Development of a sustainability reporting scheme for biofuels: A UK case study

In 2008, the UK launched the first regulatory sustainability reporting scheme for biofuels. The development of the scheme, managed by the Low Carbon Vehicle Partnership for the Department for Transport, involved extensive stakeholder engagement. The scheme has significantly increased understanding by policy-makers, the biofuels industry and its supply chains on how to monitor and manage the sustainability risks of biofuels and increase their greenhouse-gas benefits. It is providing a practical model for similar developments globally. To receive certificates in order to meet volume obligations under the Renewable Transport Fuel Obligation (RTFO), suppliers must provide a monthly carbon and sustainability report on individual batches of renewable fuels they supply into the UK. The Renewable Fuels Agency produces aggregate monthly reports of overall performance and quarterly updates of individual supplier performance. This scheme is an important first step to assist the biofuels industry to demonstrate its environmental credentials and justify the subsidies received. The paper provides a case study of the development of the scheme, its initial outcomes and outstanding challenges.     

Modification of wheat gluten with citric acid to produce superabsorbent materials

Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra‐red (FTIR) spectroscopy, thermogravimetric analysis, and water uptake. The reaction between gluten and citric acid was examined for gluten : citric acid ratios of 0.38 : 1 to 0.75 : 1 at temperatures from 100 to 130°C. More citric acid reacted for samples containing higher citric acid concentrations and at higher temperatures. FTIR analyses indicated the presence of carboxylate groups on the modified gluten samples, which resulted in modified samples having higher water uptake values than neat gluten. The sample with a gluten:citric acid ratio of 0.5 : 1 and reaction temperature of 120°C had the largest water uptake value. Also, all modified gluten samples had lower thermal stability than neat gluten. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

An LFT approach to parameter estimation

In this paper we consider a unified framework for parameter estimation problems. Under this framework, the unknown parameters appear in a linear fractional transformation (LFT). A key advantage of the LFT problem formulation is that it allows us to efficiently compute gradients, Hessians, and Gauss–Newton directions for general parameter estimation problems without resorting to inefficient finite-difference approximations. The generality of this approach also allows us to consider issues such as identifiability, persistence of excitation, and convergence for a large class of model structures under a single unified framework.     

Water absorbance and thermal properties of sulfated wheat gluten films

Wheat gluten films of various thicknesses formed at 30–70°C were treated with cold sulfuric acid to produce sulfated gluten films. Chemical, thermal, thermal stability, and water uptake properties were characterized for neat and sulfated films. The sulfated gluten films were able to absorb up to 30 times their weight in deionized water. However, this value dropped to 3.5 when the film was soaked in a 0.9% (w/w) NaCl solution. The films were also soaked 4 times in deionized water, and each soaking resulted in a reduced water uptake capacity. The temperature of film formation had no effect on the final water uptake properties. Also, thinner films had higher concentrations of sulfate groups than thicker films; this resulted in higher water uptake values. In addition, sulfated gluten films had comparable glass‐transition temperatures but lower thermal stabilities than the neat gluten films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of a post processing thermal anneal on pre-existing and stress induced electrically active defects in ultra-thin SiON dielectric layers

In this work we demonstrate the effects of a post processing high temperature anneal on the reliability of ultra-thin SiON layers fabricated into both nmos and pmos devices in terms of the initial gate leakage current, stress induced leakage current (SILC), and the time dependent dielectric breakdown behaviour. The devices under consideration were annealed at several temperatures up to 500 °C. We show that different mechanisms dominate the leakage behaviour at different temperatures by examining the relative leakage in the low voltage range. In particular for pmos devices, the emptying of electron traps induced by temperature and subsequent annealing of these traps alters the leakage current profiles significantly, dependent on anneal temperature. We show that annealing improves the time dependent dielectric breakdown (TDDB) lifetimes of nmos devices and examine the reasons for this.     

Analysis of the hazards for the molten cuprous chloride pouring operation in an industrial hydrogen production facility

An analysis is reported of a design for a local exhaust ventilation system for the molten cuprous chloride pouring station in an industrial plant. Heat recovery from molten cuprous chloride is a key process within the copper–chlorine (Cu–Cl) cycle of thermochemical water splitting for hydrogen production. Because of particulate matter, dust, and vapors emitted by the molten salt, an effective and safe design is crucial. The design process involves calculating duct diameters to provide the desired duct air velocity through the system. The static pressure is evaluated so that the fan size can be determined. An adequate supply of makeup air must be provided to replace the air exhausted through the ventilation system. The economics of the ventilation system and ways to protect employee health, as well as minimize the costs associated with exhaust ventilation, are also described. Copyright © 2011 John Wiley & Sons, Ltd.     

Impacts on Children of a Policy to Promote Employment and Reduce Poverty for Low-Income Parents: New Hope After 5 Years.

The impacts of New Hope, a program to increase parent employment and reduce poverty, were measured 5 years after parents were randomly assigned to program or control groups. New Hope had positive effects on children's school achievement, motivation, and social behavior, primarily for boys, across the age range 6-16. In comparison to impacts measured 2 years after program onset, effects on achievement were robust, but effects on social behavior were reduced. The program produced improvements in family income and use of organized child care and activity settings, suggesting possible pathways by which the New Hope package of policies influenced children's behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)