ABSTRACT
A homogeneous liquid phase reaction between barium chloride (BaCl(2)) and sodium sulphate (Na(2)SO(4)) was conducted in a narrow channel reactor to produce barium sulphate (BaSO(4)) precipitate. The effects of channel dimensions and channel residence times on crystal size, crystal size distribution, nucleation rates, crystal morphology and conversion of reactants were investigated at different levels of reactant supersaturation ratio. Our results indicate that the smallest particle sizes are favoured when supersaturation ratios and channel velocities are high. The minimum average particle diameter observed was approximately 0.2 microm in a channel of hydraulic diameter 0.5 mm and length 20 cm at an initial supersaturation ratio of 4483 (0.1 M), which correspond to conditions giving rise to the highest nucleation rates. It has also been observed that particle size depends on the conversion to product, the smallest particles being formed when conversion lies within the range of 30 to 40%. Conversions in excess of 60% have been reached but there is a detectable limiting effect with increased supersaturation and reduced residence times. Experiments conducted at similar levels of supersaturation under stirred tank conditions showed that particle size was consistently larger and particle size distribution was much broader than that achieved in the narrow channel reactor. Scanning electron microscopy (SEM) images of the crystals formed in the narrow channels show that spherical particles dominate in the smallest channels at high velocities whilst coarse, tabular crystals are obtained in the larger channels. Greater tendency to agglomerate is also observed at high supersaturation ratios, after one minute of reaction.
ABSTRACT
From survey data on 1000 urban Welfare AFDC children aged six to eighteen, a hierarchical cluster analysis yielded six distinct behavioral types of Welfare children. Characteristics of each type, and its relationship to treatment, ethnicity, and other variables are discussed. Advantages of this system of behavioral classification for research and population assessment are outlined.
Subject(s)
Aid to Families with Dependent Children , Child Behavior , Public Assistance , Urban Population , Achievement , Adolescent , Aggression , Child , Competitive Behavior , Cross-Sectional Studies , Delusions/epidemiology , Dependency, Psychological , Ethnicity , Female , Humans , Interview, Psychological , Juvenile Delinquency , Male , New York City , Social Class , Social Isolation , ViolenceSubject(s)
Interview, Psychological , Mental Disorders/diagnosis , Surveys and Questionnaires , Adolescent , Aggression , Aid to Families with Dependent Children , Anxiety/diagnosis , Child , Cognition Disorders/diagnosis , Depression/diagnosis , Female , Humans , Interpersonal Relations , Juvenile Delinquency , Male , Parents , Social IsolationSubject(s)
Aging , Child Behavior Disorders/complications , Adolescent , Aggression , Antisocial Personality Disorder/rehabilitation , Anxiety/complications , Child , Cross-Sectional Studies , Female , Humans , Juvenile Delinquency , Learning Disabilities/complications , Longitudinal Studies , Male , Neurotic Disorders/rehabilitation , Parent-Child Relations , Probability , Prognosis , Self Mutilation , Social Behavior Disorders/prevention & control , Social Isolation , Time FactorsSubject(s)
Child Behavior Disorders/etiology , Television , Violence , Adolescent , Aggression , Child , HumansSubject(s)
Mental Disorders/therapy , Urban Population , Adolescent , Child , Child Behavior Disorders/therapy , Child Welfare , Female , Humans , Male , Mental Disorders/epidemiology , New York CitySubject(s)
Child Behavior , Child Development , Mental Disorders/diagnosis , Adolescent , Age Factors , Child , Female , Humans , Interview, Psychological , Male , Methods , New York City , Probability , Sex FactorsABSTRACT
The multienzyme complex from Mycobacterium phlei which catalyzes the synthesis of long chain fatty acids from acetyl-CoA and malonyl-CoA requires a heat-stable fraction (stimulating factor, SF) for activity. Fractionation of heat-treated M. phlei extracts affords two stimulatory subfractions, one of which (SF(2)) can be replaced by FMN. The other (SF(1)) is further separable into 3 polysaccharides (PS(I), PS(II), and PS(III)). PS(I) contains about 95% 3-O-methylmannose and 5% mannose; the sugar composition of PS(II) and PS(III) is about 55% 6-O-methylglucose and 45% glucose for both. Each of the three purified polysaccharides, in combination with FMN, substitutes for the crude stimulating factor. The polysaccharides exert their effect on the fatty acid synthetase by lowering the K(m) for acetyl-CoA about 50-fold.
