An autoradiographic study of the binding of 3-H-chlorambucil to cells of a drug-sensitive and drug-resistant strain of the Yoshida ascites sarcoma.

The binding of chlorambucil to drug-sensitive and drug-resistant. Yoshida sarcoma cells has been investigated by an autoradiographic technique. The cells were treated with the drug at various concentrations both in vitro and in vivo. Using both light and electron microscope techniques, and by counting grains on various areas of the cell, the following conclusions were reached. (1) At all drug concentrations there was general cytoplasmic and nuclear uptake by both cell lines. There was no evidence of a specific localization in one site only or for specific exclusion of any one site. (2) At high dose levels (equivalent to 2 mM) the binding was approximately equal in both cell lines, although a few damaged cells bound much greater amounts of drug. (3) At low dose levels (equivalent to 3 mu-M) there was a higher uptake by the nucleus of the sensitive cells compared with the nucleus of the resistant cells; the cytoplasmic binding was similar.     

The structural characterization and hydroformylation activity of the tri-rhodium complex [Rh3(μ2-dppm)2(μ2-CO)3(K-CO)3]BF4

Rh₂(cod)₂(μ₂-dppm)(μ₂-Cl)]BF₄ (1) rearranges under carbon monoxide to give [Rh₃(μ₂-dppm)₂(μ₂-CO)₃(K¹-CO)₃]BF₄ (2). Complex 2 has been structurally characterized by single crystal X-ray crystallography. The hydroformylation activities of 1 and 2 were compared for substrates styrene and 1-hexene and the activity of 2 found to be unexpectedly high.     

On the toughness of photopolymerizable (meth)acrylate networks for biomedical applications

Photopolymerizable networks are being explored for a variety of biomedical applications because they can be formed in situ, rendering them useful in minimally invasive procedures. The purpose of this study was to establish fundamental relationships between toughness, network chemical structure, and testing temperature of photopolymerizable (meth)acrylate networks deformed in air and under hydrated conditions. Networks were formed by combining at least one monofunctional (meth)acrylate with a difunctional methacrylate, and weight ratios were adjusted to vary the degree of crosslinking, elastic modulus, and glass transition temperature (T_g). Stress–strain behavior and toughness were determined by performing tensile strain to failure tests at temperatures spanning the glassy and rubbery regimes of each network both in air and phosphate‐buffered saline. In air, all of the networks demonstrated a peak in toughness below the network's T_g. At an “equivalent” test temperature relative to T_g, crosslinking concentration and monomer chemistry influenced the toughness of each network. Apparent toughness is significantly altered in an aqueous environment, an effect driven by water absorption into the network causing the T_g to decrease. The results from this study provide the fundamental knowledge required to guide the development of tougher photopolymerizable networks for mechanically strenuous biomedical applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Measurement of temperature in active high-power AlGaN/GaN HFETsusing Raman spectroscopy

We report on the noninvasive measurement of temperature, i.e., self-heating effects, in active AlGaN/GaN HFETs grown on sapphire and SiC substrates. Micro-Raman spectroscopy was used to produce temperature maps with ≈1 μm spatial resolution and a temperature accuracy of better than 10°C. Significant temperature rises up to 180°C were measured in the device gate-drain opening. Results from a three-dimensional (3-D) heat dissipation model are in reasonably good agreement with the experimental data. Comparison of devices fabricated on sapphire and SiC substrates indicated that the SiC substrate devices had ~5 times lower thermal resistance     

A phased array optical scanning (PHAROS) device used as a 1-to-9way switch

An optical switch is demonstrated which uses a phased array of 30 closely spaced, individually addressed electrooptic AlGaAs-GaAs waveguides to focus and steer a light beam under electronic control in a planar output waveguide. A small and potentially very high speed 1-to-9 way optical switch, (with -15 dB of crosstalk) was made by placing an array of nine output waveguides at different positions in a focal plane 1 mm from the end of the electrooptic array     

The Tar Ponds kids: Toxic environments and adolescent well-being.

Studied the impact of perceived risk from exposure to a major environmental hazard on preadolescents' and adolescents' psychological health. Ss were 261 male and female 7th-9th graders (aged 12-14 yrs) who lived in immediate proximity to the Sydney Tar Ponds (STP) in Nova Scotia, described in the local media as Canada's worst toxic waste site. A matched group of 249 Ss who lived approximately 40 km from the STP was the comparison group. During regular class time, a survey comprising measures of (1) the perception of the neighborhood, (2) depression, and (3) worries and concerns about personal and family health, environmental issues, and common preadolescent and adolescent issues was administered. The results indicate that Ss living close to the STP reported more frequent environmental and health worries than the comparison group did and that proximity to the STP predicted depression through its influence on worries. The data suggest that proximity to a major environmental hazard may have a significant effect on the mental health and emotional well-being of preadolescents and adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of deep-etched, single-mode GaAs-AlGaAs opticalwaveguides using controlled leakage into the substrate

This paper presents a detailed experimental and theoretical study of the properties of deep-etched GaAs-AlGaAs optical waveguides designed using a version of the spectral index method which predicts mode losses due to leakage through the lower cladding into the high index GaAs substrate. By predicting and measuring the mode losses due to this mechanism as a function of guide width, we show that waveguides formed by reactive ion etching through the core to the lower cladding layer can be both low-loss (0.2 dB/cm) and single-mode even with core thicknesses and guide widths as large as 4.8 and 5.6 μm, respectively. We demonstrate the advantages of this type of guide for making compact integrated optic devices     

A colorimetric assay of pancreatic lipase: Rapid detection of lipase and colipase separated by gel filtration

A rapid assay for pancreatic lipase (E.C., glycerol-ester hydrolase 3.1.1.3) is described. The assay is based on the color change of a pH indicator as butyric acid is released from the substrate tributyrin. A mixture made with tributyrin and the water soluble components of the assay is ideally suited for use as a rapid test as, for example, when assaying chromatography fractions. Quantitative data can be obtained by measuring the disappearance of absorbance at 557 nm versus a blank reaction. The assay has been used in the rapid preparation of colipase-free lipase and colipase.     

Integration of a superlattice limiter into the HBT emitter forimproved operational reliability

A common problem limiting the output power of multiple finger heterojunction bipolar transistors (HBT's) is nonuniform current flow in the fingers, resulting from an underlying nonuniform temperature distribution. We have fabricated HBT devices containing an integrated superlattice region to help overcome this problem. We demonstrate that the superlattice functions as a temperature-dependent resistive current limiter in a single finger device at dc and RF. Furthermore, the RF performance of the HBT was not compromised by the inclusion of the superlattice structure     

Isolation and characterization of Lake Erie bacteria that degrade the cyanobacterial microcystin toxin MC-LR

Microcystin-LR (MC-LR) is a cyclic hepatotoxin produced by cyanobacteria, including Microcystis sp. and Planktothrix sp. Harmful algal blooms (HABs) in Lake Erie have become a major human health concern in recent years, highlighted by the August 2014 City of Toledo, Ohio, municipal water “do not drink” order that affected nearly 500,000 residents for 3?days. Given that microcystin degrading bacteria have been reported from HAB-affected waters around the world, we hypothesized that MC-LR degrading bacteria could be isolated from Lake Erie. To test this hypothesis, 13 water samples were collected from various Lake Erie locations during the summers of 2014 and 2015, MC-LR was continuously added to each water sample for 3 to 5?weeks to enrich for MC-LR-degrading bacteria, and MC-LR was quantitated over time. Whereas MC-LR was relatively stable in sterile-filtered lake water, robust MC-LR degradation (up to 19?ppb/day) was observed in some water samples. Following the MC-LR selection process, 67 individual bacterial isolates were isolated from MC-LR degrading water samples and genotyped to exclude potential human pathogens, and MC-LR degradation by smaller groups of bacterial isolates (e.g., groups of 22 isolates, groups of 11 isolates, etc.) was examined. Of those smaller groups, selected groups of four to five bacterial isolates were found to degrade MC-LR into non-toxic forms and form robust biofilms on siliconized glass tubes. Taken together, these studies support the potential use of isolated bacterial isolates to remove MC-LR from drinking water.