Photobiological hydrogen production from Synechocystis sp. PCC 6803 encapsulated in silica sol–gel

Hydrogen production was measured from viable wild-type and M55 mutant cells of Synechocystis sp. PCC 6803 encapsulated in silica sol–gel derived from tetraethoxysilane, tetramethoxysilane, and a mixture of tetraethoxysilane with methyltriethoxysilane. Glycerol and polyethylene glycol were used as additives in concentrations up to 14 wt.% to increase porosity and pore connectivity and to reduce stress on the encapsulated cells. Mixtures were evaluated for hydrogen production in a high-throughput screening assay, and samples were imaged with environmental scanning electron microscopy. Compositions showing improved H₂ production were selected for further study via quantitative analysis of H₂ production in GC vial assays. H₂ production activity was monitored for up to 5 days and H₂ production from encapsulated cells was observed at levels comparable to or exceeding cells suspended in liquid media.     

Measurement of Fibre Tuft Weight in an Air Duct using Optical Methods

The feasibility of using a Charge-Coupled Device (CCD) linescan camera to evaluate the weight of fibre tufts moving in an air duct is reported. A theoretical study of the measurement of the light transmission of fibre tufts is presented and the theoretical models are verified by experimental results. The accuracy of the results is improved by a modification of the air duct shape. The fibre tuft speed and the optical uniformity are also discussed.     

A filtering algorithm for k-mismatch with don't cares

We present a filtering based algorithm for the k-mismatch pattern matching problem with don't cares. Given a text t of length n and a pattern p of length m with don't care symbols in either p or t (but not both), and a bound k, our algorithm finds all the places that the pattern matches the text with at most k mismatches. The algorithm is deterministic and runs in Θ(nm1/3k1/3log2/3m) time.     

The effects of technical difficulties on learning and attrition during online training.

Although online instruction has many potential benefits, technical difficulties are one drawback to the increased use of this medium. A repeated measures design was used to examine the effect that technical difficulties have on learning and attrition from voluntary online training. Adult learners (N = 530) were recruited online and volunteered to participate in a 4-hr training program on using computer spreadsheets. Technical difficulties were inserted in some of the training modules in the form of error messages. Using multilevel modeling, the results indicated that the presence of these technical difficulties impaired learning, such that test scores were lower in modules where trainees encountered technical difficulties than in modules where they did not encounter technical difficulties. Furthermore, the effect on learning was greater among trainees who eventually withdrew from the course than among trainees who completed the course. With regards to attrition, pretraining motivation provided a buffer against dropping out, especially when trainees encountered technical difficulties. Learning also predicted attrition from the subsequent module, such that attrition was higher among trainees with low test scores in the previous module. The current study disentangles some of the implications of technical difficulties and suggests that organizations should provide trainees with the technical support required to overcome technical difficulties in training. Furthermore, the findings contribute to our theoretical understanding of the implications of interruptions on performance in online training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constant-bulk False-twist Texturing. Part I: Principle and Method

Current false-twist texturing processes are all carried out under constant-temperature conditions. White the product is good and commercially acceptable, changes in bulk and hence in dyeability do occur, due, for example, to alterations in yarn properties caused by changes in package build from inside to outside. New work described in this paper shows that, by texturing at constant bulk, substantially improved yarn and fabrics can be obtained. The new process developed at UMIST uses very small heaters (4–8 inches in length) under feedback control. The bulk and dyeability of the textured yarn are monitored on-line. A closed-loop system is used, and texturing conditions are automatically changed to keep the bulk and dyeability of the textured yarn constant. In this new process, the texturing temperature is changed in such a way as to keep the bulk constant. The process is therefore non-isothermal, in contrast to the isothermal, constant-temperature approach of all current false-twist texturing equipment. The principles of on-line bulk measurement are briefly discussed and it is shown theoretically that, if a tension barrier is deliberately introduced into the second zone of the false-twist threadline, then measurement of yarn velocity correlates with bulk.     

Phase Stability and Electrical Conductivity in Gd2Ti2O7-Gd2Mo2O7 Solid Solutions

Solid solutions in the Gd₂(Ti1-yMoy)2O7 pyrochlore system, with y = 0.1, 0.3, 0.5, and 0.7, have been investigated as potential candidates for the anode material of solid-oxide fuel cells. The electrical conductivity, stability range, and optimal synthesis conditions of the pyrochlore phase have been explored by electrical, coulometric titration, and X-ray diffractometry techniques. As the molybdenum content increases, the maximum conductivity increases to a value of 70 S/cm for y = 0.7 at 1000°C, whereas the stability range in the oxygen partial pressure (pO2) decreases to just over two orders of magnitude in pO2 in the temperature range of 600°-1000°C. A decomposition reaction that leads to decreased conductivity in oxidizing atmospheres is proposed.     

The achievable accuracy in estimating the instantaneous phase andfrequency of a constant amplitude signal

The approach is based on modeling the signal phase by a polynomial function of time on a finite interval. The phase polynomial is expressed as a linear combination of the Legendre basis polynomials. First, the Cramer-Rao bound (CRB) of the instantaneous phase and frequency of constant-amplitude polynomial-phase signals is derived. Then some properties of the CRBs are used to estimate the order of magnitude of the bounds. The analysis is extended to signals whose phase and frequency are continuous but not polynomial. The CRB can be achieved asymptotically if the estimation of the phase coefficients is done by maximum likelihood. The maximum-likelihood estimates are used to show that the achievable accuracy in phase and frequency estimation is determined by the CRB of the polynomial coefficients and the deviation of true phase and frequency from the polynomial approximations