SiO2 masking against phosphorus diffusion using a P2O5 source

The masking of silicon against deep P₂O₅ diffusion by a 1-μ thick SiO₂ layer has been investigated. One aspect of masking failure has been related to mounds of phosphorus silicate glass, grown on the oxide during the P₂O₅ deposition, causing spot penetration of phosphorus through the oxide and into the silicon. Such spots can increase in density, diameter and depth during the subsequent diffusion. They link up and form a continuous, but not uniform n-type layer under the oxide. Residual water vapour in the deposition systems and particle deposits on wafers during washing have been shown to be the factors that contribute to the growth of mounds.     

The Topochemistry of Delignification Shown by Pulping Middle Lamella and Secondary Wall Tissue from Black Spruce Wood

Fractions of tissue from the secondary wall and middle lamella of black spruce wood were pulped by the kraft, acid-sulphite and acid-chlorite methods. In all cases, the delignification of the secondary wall tissue was more rapid than that for the middle lamella tissue. This topochemical effect was largest in kraft pulping. In acid-sulphite pulping the effect was less than in kraft, while in acid-chlorite pulping the effect was smallest. Thus the results confirmed in general the previously reported trends based on microscopic observation. However, in earlier work there was no topochemical difference found in acid-chlorite pulping, even at high delignification. In the present work, the topochemical effect in acid-chlorite pulping increased rapidly above 50% delignification.     

Determining the microbiological criteria for lot rejection from the performance objective or food safety objective

The Microbiological Criteria (MC) is a set of parameters used to determine whether a specific lot of food is acceptable or not. These parameters are the microbial test protocol and its sensitivity, the confidence level that an unacceptable lot will be detected, the number of samples to be taken and the number of positive samples that are allowed before rejecting the lot. Determining the microbiological criteria begins with knowledge of the distribution of contamination from samples within a lot, particularly within a lot that is just at the unacceptable level of the microbial hazard. The just unacceptable lot can be defined by the Food Safety Objective (FSO) or Performance Objectives (PO), the small fraction of samples that can exceed these values and the standard deviation of the samples from the lot. With this information, a microbial test protocol is chosen to have a sensitivity level that would detect between approximately 15% and 45% of the samples. A confidence level for the MC and the number of positive samples that would be acceptable (c value which is usually zero) are also chosen. With this information the number of samples (n) required can be calculated. A critical factor in setting the microbiological criteria is the sensitivity of the microbiological test (m value). The sample size (weight) and sampling procedure can affect the standard deviation of the samples, particularly foods with non-homogeneous distribution and low numbers of microorganisms. Sampling, sample preparation and analytical procedures that reduce the variation between the samples will affect the choice of m value and maximum lot mean that meets the MC.     

COGNITIVE AND BEHAVIORAL MODEL ENSEMBLES FOR AUTONOMOUS VIRTUAL CHARACTERS

Cognitive and behavioral models have become popular methods for creating autonomous self‐animating characters. Creating these models present the following challenges: (1) creating a cognitive or behavioral model is a time‐intensive and complex process that must be done by an expert programmer and (2) the models are created to solve a specific problem in a given environment and because of their specific nature cannot be easily reused. Combining existing models together would allow an animator, without the need for a programmer, to create new characters in less time and to leverage each model's strengths, resulting in an increase in the character's performance and in the creation of new behaviors and animations. This article provides a framework that can aggregate existing behavioral and cognitive models into an ensemble. An animator has only to rate how appropriately a character performs in a set of scenarios and the system then uses machine learning to determine how the character should act given the current situation. Empirical results from multiple case studies validate the approach.     

Interpretation of simulation studies for efficient estimation of population pharmacokinetic parameters

OBJECTIVE: To develop new approaches for evaluating results obtained from simulation studies used to determine sampling strategies for efficient estimation of population pharmacokinetic parameters. METHODS: One-compartment kinetics with intravenous bolus injection was assumed and the simulated data (one observation made on each experimental unit [human subject or animal]), were analyzed using NONMEM. Several approaches were used to judge the efficiency of parameter estimation. These included: (1) individual and joint confidence intervals (CIs) coverage for parameter estimates that were computed in a manner that would reveal the influence of bias and standard error (SE) on interval estimates; (2) percent prediction error (%PE) approach; (3) the incidence of high pair-wise correlations; and (4) a design number approach. The design number (phi) is a new statistic that provides a composite measure of accuracy and precision (using SE). RESULTS: The %PE approach is useful only in examining the efficiency of estimation of a parameter considered independently. The joint CI coverage approach permitted assessment of the accuracy and reliability of all model parameter estimates. The phi approach is an efficient method of achieving an accurate estimate of parameter(s) with good precision. Both the phi for individual parameter estimation and the overall phi for the estimation of model parameters led to optimal experimental design. CONCLUSIONS: Application of these approaches to the analyses of the results of the study was found useful in determining the best sampling design (from a series of two sampling times designs within a study) for efficient estimation of population pharmacokinetic parameters.     

Organic Thin Film Transistors with Polymer Brush Gate Dielectrics Synthesized by Atom Transfer Radical Polymerization

Low operating voltage is an important requirement that must be met for industrial adoption of organic field‐effect transistors (OFETs). We report here solution fabricated polymer brush gate insulators with good uniformity, low surface roughness and high capacitance. These ultra thin polymer films, synthesized by atom transfer radical polymerization (ATRP), were used to fabricate low voltage OFETs with both evaporated pentacene and solution deposited poly(3‐hexylthiophene). The semiconductor‐dielectric interfaces in these systems were studied with a variety of methods including scanning force microscopy, grazing incidence X‐ray diffraction and neutron reflectometry. These studies highlighted key differences between the surfaces of brush and spun cast polymethyl methacrylate (PMMA) films.     

High-pressure washing treatments to remove obscure mealybug (Homoptera: Pseudococcidae) and lightbrown apple moth (Lepidoptera: Tortricidae) from harvested apples

Mixed life stages of obscure mealybug, Pseudococcus viburni (Signoret), and late 1st-instar or early 2nd-instar lightbrown apple moth, Epiphyas postvittana (Walker), on 'Royal Gala' apples (Malus domestica Borkhausen) were exposed to standard packhouse processing with and without addition of high-pressure apple washer treatments. Insect removal and mortality were assessed. After standard packhouse processing approximately 60% of P. viburni remained on their host apples. The 2 high-pressure apple washer treatments (500 and 800 psi at 2.0 rods/s) were equally effective and significantly reduced the number of P. viburni on apples compared with the packhouse control. High-pressure apple washer removal by location decreased in the following order: calyx cavity outside the sepals > cheek approximately stem cavity > or = calyx beneath sepals. About half of the E. postvittana larvae infesting apples was removed by standard packhouse processing. Removal rates were similar for all locations on open-calyxed apples. However, no removal occurred from the calyx beneath the sepals if the apple calyx was closed. All 4 high-pressure apple washer treatments tested (500 and 800 psi at 1.0 and 2.0 rods/s) halved the number of larvae on the apple exterior relative to the packhouse control. The pattern of removal for larvae on open-calyxed apples was calyx outside sepals approximately stem cavity > calyx beneath the sepals approximately cheek. A similar pattern was evident for larvae on closed-calyxed apples, except insects beneath the sepals evaded removal. The persistence of insects on the apple cheek reflects the high proportion of larvae inside tunnels in this location compared with other apple locations. Removal of internally positioned insects was much lower than that of externally positioned insects.     

Programmable selectivity for GC with series-coupled columns using pulsed heating of the second column

A series-coupled ensemble of a nonpolar dimethyl polysiloxane column and a polar trifluoropropylmethyl polysiloxane column with independent at-column heating is used to obtain pulsed heating of the second column. For mixture component bands that are separated by the first column but coelute from the column ensemble, a temperature pulse is initiated after the first of the two components has crossed the column junction point and is in the second column, while the other component is still in the first column. This accelerates the band for the first component. If the second column cools sufficiently prior to the second component band crossing the junction, the second band experiences less acceleration, and increased separation is observed for the corresponding peaks in the ensemble chromatogram. High-speed at-column heating is obtained by wrapping the fused-silica capillary column with resistance heater wire and sensor wire. Rapid heating for a temperature pulse is obtained with a short-duration linear heating ramp of 1000 degrees C/min. During a pulse, the second-column temperature increases by 20-100 degrees C in a few seconds. Using a cold gas environment, cooling to a quiescent temperature of 30 degrees C can be obtained in approximately 25 s. The effects of temperature pulse initiation time and amplitude on ensemble peak separation and resolution are described. A series of appropriately timed temperature pulses is used to separate three coeluting pairs of components in a 13-component mixture.