An overview of environmental and toxicological aspects of aromatic hydrocarbons. IV. Ethylbenzene

The solvent aspects of exposure to ethylbenzene are reviewed via an initial examination of the production, use, occurrence, and disposition of ethylbenzene as well as populations potentially at risk. While occupational exposure to ethylbenzene during its production and subsequent conversion to styrene is believed to be minimal, the broader occupational exposure to ethylbenzene during the production and use of 'mixed xylenes' is another area of concern. The general public can be exposed to ethylbenzene in ambient air as a result of its occurrence in motor vehicle exhaust. Additional exposure can arise in indoor environments, mostly from passive exposure to cigarette smoke. Ethylbenzene is primarily an irritant to the skin and mucous membranes and possesses narcotic properties at high concentrations.     

Unsteady mass transfer with a heterogeneous chemical reaction during laminar flow past a sphere

Unsteady mass transfer toward a solid sphere is investigated in the region of Peclet numbers 1Pe1000. Diffusion flow in the presence of a first-order chemical reaction is calculated and the relaxation time of the steady regime as a function of the Peclet number is determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 1, pp. 73–79, January, 1976.     

Carcinogenicity and mutagenicity of solvents I. Glycidyl ethers,dioxane, nitroalkanes,dimethylformamide and allyl derivatives

The carcinogenicity and/or mutagenicity as well as structural features and relationships of the glycidylethers (principally phenyl-, butyl-, allyl-, and isopropyl-), dioxane, nitroalkanes (nitro methane, ethane and propane), dimethylformamide and allyl derivatives (chloride, alcohol and amine) were examined. Additionally, considerations of the production, use patterns, estimated populations at risk, TLV's and metabolism of the above agents were discussed.     

Problem solving: A model for supervision in professional psychology.

Reviews literature on problem-solving models, their application to psychology and other fields, models of supervision, and supervision in psychology. The following processes are addressed: problem identification, generation of alternative solutions, solution evaluation, decision making, performance, and outcome evaluation. Implementation of the problem-solving model and possible sources of difficulty are discussed. This model has the advantages of being atheoretical, systematic, and appropriate for use in clinical, counseling, and school psychology. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An overview of environmental and toxicological aspects of aromatic hydrocarbons. II. Toluene

The salient aspects of the exposure to toluene were reviewed via an initial examination of the production, use, occurrence and disposition of toluene, as well as populations at potential risk. Special note should be taken as to the increasing use of toluene as a "safe" replacement for benzene in solvent applications and its increasing use in many consumer products. There is a broad potential for exposure by industrial workers and the general public (via vehicle exhausts and consumer products). The effects on humans and animals as well as the genetic effects of toluene were also reviewed following an initial consideration for its absorption and elimination. The narcotic and neurotoxic properties of toluene represent the main recognized health hazards to humans.     

Learners' questions and comprehension in a tutoring setting.

Three experiments, presented within the framework of Activity Theory, deal with the relationship between adult learners' questions and subsequent comprehension in a tutorial learning setting. Students were first given verbal instructions (acquisition) to a novel card game and then asked to play one hand with the teacher (implementation). In Experiment 1, there was no correlation between number of questions asked during acquisition and comprehension, but questions during implementation were negatively correlated with comprehension. In Experiment 2, learners whose questions were answered during acquisition scored higher than those whose questions were not answered. In Experiment 3, learners whose questions were answered during implementation showed greater gains in comprehension than those whose questions were answered during acquisition. Individual differences in question-asking during implementation but not acquisition were significantly related to comprehension. The results confirm the view that questions answered during knowledge implementation more effectively aid comprehension than those answered during acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast gradient echo MR imaging of the liver enhanced with superparamagnetic iron oxide

Urinary proteins of patients with diabetes mellitus (DM) were analyzed using cellulose acetate membrane electrophoresis, to determine the clinical usefulness of fraction patterns of the proteins in detecting the group at high risk for diabetic nephropathy. We divided the protein patterns into 5 groups. Four groups (I, II, III, IV) were found in the healthy group and a newly classified group was termed group 0 and was characterized by a prominent albumin peak with a negligible or small globulin peak. The incidence of groups 0, I, II, III, and IV, was 36.6%, 13.3%, 18.7%, 10.7% and 22.7%, respectively. This distribution was clearly different from that of healthy subjects and the most characteristic feature of diabetics was that group 0 accounted for 36.6% of the total cases. Characteristic features of each group were examined from the aspect of laboratory and clinical findings. Urinary protein patterns were concluded to be useful not only to predict the high risk group for diabetic nephropathy in the preclinical stage but also to discriminate nephropathic types of glomerular or tubular origin. It is useful for clinicians to know the risk stage and prognosis for diabetic nephropathy.     

Assessment of myocardial viability by dobutamine echocardiography, positron emission tomography and thallium-201 SPECT: correlation with histopathology in explanted hearts

OBJECTIVES: We examined the relationship among viability assessment by dobutamine echocardiography (DE), positron emission tomography (PET) and thallium-201 single-photon emission computed tomography (TI-SPECT) to the degree of fibrosis. BACKGROUND: DE, PET and TI-SPECT have been shown to be sensitive in identifying viability of asynergic myocardium. However, PET and TI-SPECT indicated viability in a significant percentage of segments without dobutamine response or functional improvement after revascularization. METHODS: Twelve patients with coronary artery disease and severely reduced left ventricular function (EF 14.5+/-5.2%) were studied with DE prior to cardiac transplantation: 5 had additional PET and 7 had TI-SPECT studies. Results of the three techniques were compared to histologic findings of the explanted hearts. RESULTS: Segments with >75% viable myocytes by histology were determined to be viable in 78%, 89% and 87% by DE, PET and TI-SPECT; those with 50-75% viable myocytes in 71%, 50% and 87%, respectively. Segments with 25-50% viable myocytes showed response to dobutamine in only 15%, but were viable in 60% by PET and 82% by TI-SPECT. Segments with <25% viable myocytes responded to dobutamine in 19%; however, PET and TI-SPECT demonstrated viability in 33% and 38%, respectively. Discrepant segments without dobutamine response but viability by PET and SPECT had significantly more viable myocytes by pathology than did those classified in agreement to be nonviable but had significantly less viable myocytes than those classified in agreement to be viable (p < .001). CONCLUSIONS: These findings suggest that contractile reserve as evidenced by a positive dobutamine response requires at least 50% viable myocytes in a given segment whereas scintigraphic methods also identify segments with less viable myocytes. Thus, the methods may provide complementary information: Nuclear techniques appear to be highly sensitive for the detection of myocardial viability, and negative tests make it highly unlikely that a significant number of viable myocytes are present in a given segment. Conversely, dobutamine echo may be particularly useful for predicting recovery of systolic function after revascularization.     

Some problems of convective diffusion to a spherical particle with Pe ≤ 1000

The problem of convective heat and mass exchange during the slow motion of a single drop in a uniform and a shear stream, as well as during the motion of a gas bubble in a power-law liquid, is solved using finite-difference methods.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 6, pp. 1053–1058, June, 1977.     

Potential halogenated industrial carcinogenic and mutagenic chemicals. IV. Halogenated aryl derivatives.

A variety of halogenated aryl derivatives possess significant activity as solvents for pesticides, heat transfer agents, pesticide intermediates, additives for rubber products, intermediates in organic synthesis and as insect repellants and deodorants. Ortho- and para-dichlorobenzenes; 1,2,4-trichloro- and hexachlorobenzene, as well as bromobenzenes and benzylchloride were reviewed principally in terms of their synthesis, areas of utility, stability, distribution, reactivity, levels of exposure, populations at risk, metabolism, carcinogenicity and mutagenicity.