Gas-liquid chromatographic determination of azinphos ethyl in human plasma and in mouse plasma, tissue, and fat

A new method for the determination of azinphos ethyl (O,O-diethyl-S-(4-oxo-1,2,3-benzotriazin-3(4H)-ylmethyl) phosphorodithioate) in human plasma and in mouse plasma, tissue, and fat has been developed. The method is based on extraction with benzene or hexane and cleanup of fat and tissue samples by a minicolumn containing Florisil and sodium sulfate. Azinphos ethyl is eluted from the column with 10% acetonitrile in benzene and is concentrated to an appropriate volume for gas-liquid chromatographic analysis, using a 63Ni electron capture detector and a glass column containing 3% OV-1 on Gas-Chrom Q. The method is sensitive to 0.005 ppm in human plasma, 0.01 ppm in mouse plasma, 0.08 ppm in mouse liver, 0.05 ppm in mouse brain, and 0.10 ppm in mouse fat. The limit of detection is 2 pg; mean recoveries ranged from 96 to 98%.     

Ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome: dominant inheritance and variable expression

The influence of thymosterin on immunological reactivity of NZB mice was investigated. Thymosterin was administered three times per week for a period of six weeks to male and female NZB mice. Only lymphocytes from untreated female mice gave the positive results in the macrophage migration inhibition test using native DNA as the stimulating antigen. This effect was suppressed in thymosterin treated females. The administration of thymosterin therefore appears to correct the in vitro delayed hypersensitivity to DNA antigen.     

Electrical and rheological percolation in poly(vinylidene fluoride)/multi‐walled carbon nanotube nanocomposites

Nanocomposites of poly(vinylidene fluoride) (PVDF) and multi‐walled carbon nanotubes (MWCNTs) were prepared through melt blending in a batch mixer (torque rheometer equipped with a mixing chamber). The morphology, rheological behavior and electrical conductivity were investigated through transmission electron microscopy, dynamic oscillatory rheometry and the two‐probe method. The nanocomposite with 0.5 wt% MWCNT content presented a uniform dispersion through the PVDF matrix, whereas that with 1 wt% started to present a percolated network. For the nanocomposites with 2 and 5 wt% MWCNTs the formation of this nanotube network was clearly evident. The electrical percolation threshold at room temperature found for this system was about 1.2 wt% MWCNTs. The rheological percolation threshold fitted from viscosity was about 1 wt%, while the threshold fitted from storage modulus was 0.9 wt%. Thus fewer nanotubes are needed to approach the rheological percolation threshold than the electrical percolation threshold. Copyright © 2010 Society of Chemical Industry     

Electrical,rheological and electromagnetic interference shielding properties of thermoplastic polyurethane/carbon nanotube composites

Electrically conducting rubbery composites based on thermoplastic polyurethane (TPU) and carbon nanotubes (CNTs) were prepared through melt blending using a torque rheometer equipped with a mixing chamber. The electrical conductivity, morphology, rheological properties and electromagnetic interference shielding effectiveness (EMI SE) of the TPU/CNT composites were evaluated and also compared with those of carbon black (CB)‐filled TPU composites prepared under the same processing conditions. For both polymer systems, the insulator–conductor transition was very sharp and the electrical percolation threshold at room temperature was at CNT and CB contents of about 1.0 and 1.7 wt%, respectively. The EMI SE over the X‐band frequency range (8–12 GHz) for TPU/CNT and TPU/CB composites was investigated as a function of filler content. EMI SE and electrical conductivity increased with increasing amount of conductive filler, due to the formation of conductive pathways in the TPU matrix. TPU/CNT composites displayed higher electrical conductivity and EMI SE than TPU/CB composites with similar conductive filler content. EMI SE values found for TPU/CNT and TPU/CB composites containing 10 and 15 wt% conductive fillers, respectively, were in the range ?22 to ?20 dB, indicating that these composites are promising candidates for shielding applications. © 2013 Society of Chemical Industry     

Effect of obsidan on the systemic hemodynamics of dogs in ontogeny

Investigations on dogs of different age have brought evidence that intravenous administration of 2 mg/kg of obsidan (propranolol hydrochloride) causes in 18-22-day old puppies a fall of arterial pressure due to a reduced cardiac ejection with little changing total vascular peripheral resistance. The frequency of the rhythm and conduction in the heart are slowed down. In dogs aged 3-5 years the arterial pressure remains unchanged, since the diminution of the cardiac output is attended by a greater vascular resistance.     

Growth on urea can trigger death and peroxidation of the cyanobacterium Synechococcus sp. strain PCC 7002

Laboratory conditions have been identified that cause the rapid death of cultures of cyanobacteria producing urease. Once the death phase had initiated in the stationary growth phase, cells were rapidly bleached of all pigmentation. Null mutations in the ureC gene, encoding the alpha subunit of urease, were constructed, and these mutants were no longer sensitive to growth in the presence of urea. High levels of peroxides, including lipid peroxides, were detected in the bleaching cells. Exogenously added polyunsaturated fatty acids triggered a similar death response. Vitamin E suppressed the formation of peroxides and delayed the onset of cell bleaching. The results suggest that these cyanobacterial cells undergo a metabolic imbalance that ultimately leads to oxidative stress and lipid peroxide formation. These observations may provide insights into the mechanism of sudden cyanobacterial bloom disappearance in nature.     

Steroid dehydrogenases in the adrenal gland of four species of birds: a histochemical study

The presence of 5-3deltabeta-hydroxysteroid dehydrogenase, IIbeta-hydroxysteroid dehydrogenase, 17beta-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase has been demonstrated histochemically in the adrenal gland of the rain quail Coturnix coromendalica, barn owl Tyto alba, brown crake Amaurornis akool and painted partidge Francholinus pictus. All these enzymes occurred in the inter-renal cells. No activity was observed in the chromaffin cells. It is suggested that the inter-renal cells of these four species of birds are capable of synthesizing both corticosteroids and sex steroids.