Microchip immobilized enzyme reactors for hydrolysis of methyl cellulose

Microchip immobilized enzyme reactors (microIMERs) with immobilized endoglucanases were applied for the hydrolysis of methyl cellulose (MC). MCs of various molecular weights were hydrolyzed using two microIMERs containing immobilized celloendoglucanase Cel 5A from Bacillus agaradhaerens (BaCel 5A) connected in series. Hydrolysis by the microIMER could be confirmed from the average molar masses and molar mass distributions measured by size exclusion chromatography (SEC) with online multiangle light scattering and refractive index detection. Methylated cellooligosaccharides with degrees of polymerization (DP) between 1 and 6 formed during hydrolysis were analyzed by direct infusion electrospray ionization ion-trap mass spectrometry (ESI-ITMS). Mass spectra of microIMER- and batch-hydrolyzed samples were compared and no significant differences were found, indicating that microIMER hydrolysis was as efficient as conventional batch hydrolysis. A fast and automated hydrolysis with online MS detection was achieved by connecting the microIMER to high-performance liquid chromatography and ESI-ITMS. This online separation reduced the relative intensities of interfering signals and increased the signal-to-noise ratios in MS. The microIMER hydrolysates were also subjected to SEC interfaced with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. With this technique, oligomers with DP 3-30 could be detected. The hydrolysis by the microIMER was performed within 60 min, i.e. significantly faster compared with batch hydrolysis usually performed for at least 24 h. The microIMER also allowed hydrolysis after 10 days of continuous use. The method presented in this work offers new approaches for the analysis of derivatized cellulose and provides the possibility of convenient online, fast, and more versatile analysis compared with the traditional batch method.     

Oligosaccharide dehydrogenase-modified graphite electrodes for the amperometric determination of sugars in a flow injection system

Enzyme electrodes for the determination of sugars based on solid graphite electrodes modified with oligosaccharide dehydrogenase "wired" with an osmium-based one-electron (no proton) acceptor redox hydrogel were studied as sensors in a flow injection system. The enzyme and a poly(1-vinylimidazole) (PVI) where every tenth mer is complexed with osmium (4,4'-dimethylbpy)(2)Cl, (denoted PVI(10)dmeOs) were cross-linked with poly(ethylene glycol) (diglycidyl) ether. The electrodes were active for l-arabinose, d-xylose, d-galactose, d-fructose, d-glucose, d-mannose, cellobiose, lactose, maltose, and maltooligosaccharides up to a degree of polymerization of 7. The highest relative response found was for glucose (100%) followed by maltose (40.6%) and lactose (40.6%). Fructose and isomaltotriose gave the lowest responses (<1%). Calibration curves for glucose were strictly linear in the range between 30 and 500 μM with sensitivity and apparent Michaelis-Menten constant (K(m)(app)) of 23.0 ± 1.4 μA mM(-)(1)cm(-)(2) and 4.26 ± 0.95 mM, respectively.     

Effect of Powder Purity and Second Phases on the Dielectric Properties of Lead Magnesium Niobate Ceramics

The dielectric properties of lead magnesium niobate ceramics have been studied as a function of powder purity and microstructure. Starting powder purity was shown to have d pronounced effect on the resultant dielectric properties. Values of K_max as high as 20 000 were obtained using starting powders of exceptionally high purity (99.999%), despite the formation of a pyrochlore phase. The pyrochlore phase formed as large isolated grains in the microstructure. It was found to be a cubic-type pyrochlore with a composition of Pb₂Nb_1.75Mg_0.25O_6.62. Much lower dielectric constants were obtained with samples of lower reagent-grade purity. This was partially explained by the presence of an intergranular second phase. Other factors such as lattice impurities and grain-boundary chemistry were also argued to be important.     

National survey of psychology internship directors regarding education for prevention of psychologist–patient sexual exploitation.

All directors of psychology internships accredited by the American Psychological Association (N?=?410) were surveyed about the status of internship education related to prevention of psychologist–patient sexual exploitation. Virtually all responding directors (99% of 230) reported that their program provides at least 1 session on this topic, and the same number indicated that such education should be part of the mandatory internship curriculum. Ninety-four percent of responding programs had instituted the reported training within the prior 10 years and 60% had done so within 4 years. A national mandate requiring education for prevention of psychologist–patient sexual exploitation can consolidate the apparent trend toward greater inclusion of this topic in training programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible Dome and Bump Shape Piezoelectric Tactile Sensors Using PVDF-TrFE Copolymer

In this paper, a new mold-transfer method to pattern piezoelectric polymer has been developed and applied to fabricate innovative dome and bump shape polyvinylidene-fluoride-trifluoroethylene (PVDF-TrFE) films. The dome and bump shape PVDF-TrFE films have been successfully fabricated and characterized as a sensing component for flexible tactile sensors. The tactile sensors developed using these polymer microstructures show a high sensitivity which can measure as small as 40 mN force for bump shape sensors and 25 mN for dome shape sensors. The newly developed fabrication method provides a flexible way to pattern the piezoelectric polymer with different shapes and dimensions, including bump and dome shape piezoelectric polymer microstructures. In addition, a selective dc poling method for the PVDF-TrFE film has been developed for fabricating precisely located piezoelectric sensors with minimum crosstalk. The bump and dome shape PVDF-TrFE films developed in this paper can have numerous applications for microcatheters or other minimally invasive biomedical devices.     

Rapid alcohol determination in plasma and urine by column liquid chromatography with biosensor detection

An enzyme based amperometric biosensor used as a selective and sensitive detection unit in column liquid chromatography for the determination of ethanol and methanol in biological fluids such as plasma and urine is described. The reagentless enzyme electrode is based on the co-immobilisation of alcohol oxidase and horseradish peroxidase in carbon paste. The selectivity of the biosensor was found to vary when four various alcohol oxidase enzyme preparations from Candida boidinii, Pichia pastoris, and Hansenula polymorpha were used in the biosensors described. High sensitivity could be obtained for a number of alcohols, organic acids, and aldehydes. Optimisation regarding the sensitivity and selectivity of the four alcohol oxidase co-immobilised biosensors are outlined. A fast and reliable liquid chromatographic separation system with a PLRP-S polymer based separation column used with a phosphate buffer as the mobile phase was optimised using the best biosensor which was based on alcohol oxidase from P. pastoris and which showed the highest turnover rate for alcohols, as the detector for the determination of ethanol and methanol in human urine and plasma samples. The selectivity and stability of the biosensor were retained by working at an applied potential of -50 mV versus Ag/AgCl, the optimal operational potential, and by the casting of a protective membrane on the electrode surface. High selectivity of the enzyme electrode was also found towards other easily oxidisable interfering species normally present in biological fluids. It was found that stable and reliable determinations of ethanol and methanol in plasma and urine could be performed with only a simple dilution and centrifugation step prior to injection into the liquid chromatographic system. An analysis time of 4 min was required for the assay, with a sample throughput of 13 samples h(-1).     

A Flexible Communications System for Satellite News Gathering

Satellite news gathering (SNG) requires a great deal of coordination among diverse parties. Voice and data. communications traffic is gernerated in support of SNG operations which is technical, programmatic, and administrative in nature. The origin, routing destination, and duration of this traffic cannot be fully pre-planned. Historically, SNG vehicles have not had the ability to directly dial, without any operator intervention, into the public telephone switched network: (PTSN), nor the ability to receive calls directly dialed from anywhere. The system described here, however, does allow the operators of ENS vehicles to complete and receive unattended direct-dial communications both intra-network: and also to and from telephones and data sets connected to the PTSN.     

Theory of 1- N-way phase-locked resonators

A 1-N-way resonator based on beam splitting and beam combining effects in rectangular cross-sectional multimode waveguides was recently proposed. Such a resonator structure offers a valuable way in which N low-power laser elements may be combined in a coherent fashion. We examine the case of passive 1-N-way resonators. We develop a theory of these 1-N-way structures to show that there is only one possible mode of these resonators. The theory is used to give a scaling law for the design tolerances of the beam splitting and beam combining region of the resonator.     

Accelerating COTS middleware acquisition: the i-Mate process

COTS middleware speeds e-business application deployment but can be difficult to select. The i-Mate tool provides a proven, structured software engineering process for COTS middleware acquisition. Using i-Mate in six major projects for a wide range of organizations led to highly visible, accountable, and ultimately reliable selections of COTS middleware products in greatly compressed time scales. This significantly reduced the risks associated with inappropriate product selections and made these projects more likely to succeed.