Coagulation dynamics of fractal flocs induced by enmeshment and electrostatic patch mechanisms

The size and structure of flocs during floc formation were monitored for various coagulation mechanisms. Two distinctive mechanisms, namely, enmeshment and electrostatic patch, govern the dynamics of kaolin particles coagulation by polyaluminum chloride (PACl). They were investigated by small angle static light scattering (SASLS) and solid-state ²⁷Al NMR. In addition, a novel wet SEM (WSEM) was used in-situ to image the morphology of the aggregate in aqueous solution. Synthetic suspended particles were coagulated by two PACl products, a commercial product (PACl) and one laboratory product (PACl-E). The PACl-E contained more than 60% Al₁₃ while the PACl contained only 7% Al₁₃, with large percentage of colloidal Al. For coagulation by PACl at neutral pH and high dosage where the strong repulsion between particles occurs, the enmeshment ruled by reaction-limited aggregation (RLA) results in larger sweep flocs as well as higher fractal dimensional structure. For coagulation by PACl-E at alkaline pH and low dosage, the flocs were coagulated predominately by electrostatic patch with Al₁₃ aggregates. At such condition, it is likely that diffusion-limited aggregation (DLA) predominately rule PACl-E coagulation. The fractal dimension (D_s) values of PACl and PACl-E flocs formed at enmeshment and electrostatic patch increased with dosage, respectively. When breakage of flocs occurs, the breakage rate of PACl-E flocs is slower than that of sweep flocs. By WSEM imaging, the adsorption of spherical Al precipitates onto the particles was observed to form sweep flocs with a rough and ragged contour, while the PACl-E flocs were formed with a smooth and glossy structure.     

Packaging postponement: a global packaging strategy

Postponement applications have been growing in recent years as international firms increasingly develop global products that are customized for local markets. The purpose of this article is to provide an understanding of the logistical principles of postponement and speculation. It explores the factors that favour packaging postponement: (a) modular products that can be customized for local markets; (b) products that gain volume, weight or value from packing; (c) unpredictable demand; (d) a large number of market‐based variations for a single formulation; and (e) situations where economies of scale in packaging and logistics can be optimized. Examples are presented. Copyright © 2000 John Wiley & Sons, Ltd.     

Sub-Critical Crack Growth Behavior of a Low-Temperature Co-Fired Ceramic

The strength of sintered low-temperature co-fired ceramic (LTCC) disks was measured under dry (<2% relative humidity [RH]) and wet (98% RH) conditions, using ring-on-ring, biaxial-flexure testing in the stressing rate range of 0.002–2 MPa/s. The empirical sub-critical crack growth parameters, n and A , were calculated. The values of the parameters in the wet environment were higher than in the dry environment. It is argued that the high RH n value is more representative of material behavior. Results of fractographic examination are reported and expected lifetime and safe design stresses for LTCC are calculated.     

The relationship between chain connectivity and domain stability in the equilibrium and kinetic folding mechanisms of dihydrofolate reductase from E.coli

The role of domains in defining the equilibrium and kinetic folding properties of dihydrofolate reductase (DHFR) from Escherichia coli was probed by examining the thermodynamic and kinetic properties of a set of variants in which the chain connectivity in the discontinuous loop domain (DLD) and the adenosine-binding domain (ABD) was altered by permutation. To test the concept that chain cleavage can selectively destabilize the domain in which the N- and C-termini are resident, permutations were introduced at one position within the ABD, one within the DLD and one at a boundary between the domains. The results demonstrated that a continuous ABD is required for a stable thermal intermediate and a continuous DLD is required for a stable urea intermediate. The permutation at the domain interface had both a thermal and urea intermediate. Strikingly, the observable kinetic folding responses of all three permuted proteins were very similar to the wild-type protein. These results demonstrate a crucial role for stable domains in defining the energy surface for the equilibrium folding reaction of DHFR. If domain connectivity affects the kinetic mechanism, the effects must occur in the sub-millisecond time range.     

Women's sexuality: Behaviors, responses, and individual differences.

Classic and contemporary approaches to the assessment of female sexuality are discussed. General approaches, assessment strategies, and models of female sexuality are organized within the conceptual domains of sexual behaviors, sexual responses (desire, excitement, orgasm, and resolution), and individual differences, including general and sex-specific personality models. Where applicable, important trends and relationships are highlighted in the literature with both existing reports and previously unpublished data. The present conceptual overview highlights areas in sexual assessment and model building that are in need of further research and theoretical clarification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in stress and coping processes.

The dramatic increase in the numbers of people who are living into old age has been accompanied by a growing interest among psychologists and health care professionals in their sources of stress and how they cope with them. Despite this interest, little is known about normative stress and coping patterns and the ways in which these patterns differ in older and younger people. This study, which draws on stress and coping theory, compares younger and older community-dwelling adults in daily hassles and eight kinds of coping. Two interpretations of age differences are evaluated: a developmental interpretation, which says that there are inherent, stage-related changes in the ways people cope as they age, and a contextual interpretation, which says that age differences in coping result from changes in what people must cope with. The findings indicate that there are clear age differences in hassles and coping. Overall, the findings tend to support the developmental interpretation, although the contextual interpretation also applies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

More evidence for generalized poor performance in facial emotion perception in schizophrenia.

Previous studies showing that schizophrenic patients have a deficit in the ability to perceive facial expressions of emotion in others often have not used a differential deficit design and standardized measures of emotion perception. Using standardized and cross-validated measures in a differential deficit design, S. L. Kerr and J. M. Neale (see record 1993-29687-001) found no evidence for a deficit specific to emotion perception among unmedicated schizophrenic patients. The present study replicated and extended the findings of Kerr and Neale in a sample of medicated schizophrenic patients. Results showed that medicated patients performed more poorly than controls overall; however, they performed no worse on facial emotion perception tasks than on a matched control task. These findings support Kerr and Neale's conclusion that schizophrenic patients do not have a differential deficit in facial emotion perception ability. Future research should examine the nature of schizophrenic patients generalized poor performance on tests of facial emotion perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The utility of IgA antibody to human immunodeficiency virus type 1 in early diagnosis of vertically transmitted infection. National Institute of Allergy and Infectious Diseases and National Institute of Child Health and Human Development Women and Infants Transmission Study Group

OBJECTIVE: To determine the sensitivity and specificity of anti-human immunodeficiency virus (HIV) IgA in identifying infected infants at or before 6 months of age among the offspring of HIV-infected mothers. DESIGN: Prospective comparison of anti-HIV IgA measurement performed in 2 different laboratories by 2 different methods with the criterion standard of blood culture. SETTING: Five centers in the United States and Puerto Rico. PATIENTS: Population-based sample of 156 infants of HIV-infected mothers in the Women and Infants Transmission Study. MAIN OUTCOME MEASURES: Results of anti-HIV IgA test in relation to the infection status of the infants as measured by blood culture. RESULTS: Six-month plasma or serum samples were first tested in the 2 laboratories. The sensitivity and specificity of anti-HIV IgA in detecting infected infants at this age by laboratories 1 and 2 were 69% and 63% and 100% and 99%, respectively. A look-back study of samples obtained at birth, 1, 2, and 4 months was then performed on all infected children and a matched set of uninfected children. The performance of the test at birth was unsatisfactory in both laboratories (sensitivity 44% and 33%, specificity 43% and 60%), whether peripheral or cord blood was examined. At 1, 2, and 4 months, the sensitivity of the test was lower than at 6 months, but specificity was high. A modest correlation of absent anti-HIV IgA antibody and low percentage of CD4 cells in peripheral blood was seen at 6 months of age. CONCLUSIONS: The anti-HIV IgA test has moderate sensitivity and high specificity for the diagnosis of HIV infection at 6 months of age in the offspring of infected mothers.     

Helping the suicidal client: Some aspects of assessment and treatment.

All manifestations of suicidal intent need to be taken seriously by the clinician, who must make an assessment of the level of suicidal risk and implement an active suicide prevention plan when risk is judged to be substantial. Suicidal behavior is more difficult to predict in schizophrenic compared with depressed people; factors correlated with increased risk of suicide in both contexts are elaborated. Hospitalization is indicated when acute suicidal risk is assessed to be high; its length is ideally limited to the period of acute risk, which may be as short as several days. During hospitalization, there should be active intervention to change real-life conditions, such as lack of social support, which may be central to the person's motivation to commit suicide. Antipsychotic medication may be introduced and the person helped to continue with it as an outpatient. For those at lesser levels of acute risk, outpatient treatment is seen as appropriate and effective. An important feature of such a plan is the involvement of the person's family and associates. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Women's sexual self-schema.

Sexual self-schemas are cognitive generalizations about sexual aspects of oneself that are derived from past experience, manifest in current experience, influential in the processing of sexually relevant social information, and guide sexual behavior. In Part 1, a measure of a cognitive self-view of women's sexuality was developed. The construct includes 2 positive aspects, an inclination to experience passionate–romantic emotions and a behavioral openness to sexual experience, and a negative aspect, embarrassment or conservativism, which may be a deterrent to sexual–romantic affects and behaviors. In Part 2, the role of sexual schema in intrapersonal and interpersonal aspects of sexuality was examined. In Part 3, a bivariate model was explored and 4 self-views (positive, co-schematic, aschematic, and negative) were proposed and compared. (PsycINFO Database Record (c) 2010 APA, all rights reserved)