Evaluation and characterization of vector fluids and peroxides in a process of in situ compatibilization of polyethylene and polystyrene

An organic functional silane was found to be the most efficient among several vector fluids in reactive blend compatibilization of the polyethylene (PE) / polystyrene (PS) / peroxide / vector fluid system. This paper involves further analysis of this reactive blending system. Surface tension data was used to calculate spreading coefficients which were compared to the amount of PE-PS copolymer formed during blending. A good correlation between a computed spreading coefficient and the degree of grafting of PS onto PE was found. The results suggest that the pattern of distribution of the vector fluid in PE / PS blends is the key factor leading to effective results. Furthermore, different peroxides were evaluated in PE / PS blends, in order to determine the dependence of PE / PS interfacial grafting reaction on the structure of the peroxide.     

Relation of stressful life events to metabolic control among adolescents with diabetes: 5-year longitudinal study.

Objective: To determine the relation of stressful life events to metabolic control. Design: We interviewed adolescents with Type 1 diabetes (n = 132; average age at enrollment = 12 years) annually for 5 years. Measures: Each year we administered measures of stressful life events, psychological distress, and self-care behavior. We downloaded data from blood glucose meters, and obtained measures of metabolic control (hemoglobin A1c) from medical records. Results: Using longitudinal growth curve modeling, stressful life events predicted greater psychological distress, poorer self-care behavior, and worse metabolic control in both cross-sectional and longitudinal (lagged) analyses. Cross-sectionally, many of these relations were stronger among older than younger adolescents. Self-care behavior partly mediated this association. Conclusion: Stressful life events are related to poor metabolic control—especially for older adolescents. A primary mechanism appears to be a lack of good self care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using group decision support systems to brainstorm and evaluate prospective consultation interventions.

In this age of rapidly progressing technology, it is important to stay abreast of innovations that can enhance consultation modalities and maximize consultation effectiveness. Collaborative work technology using group decision support systems (GDSSs) seems to address both of these issues. The use of GDSSs for teaching, training, and consultation has been shown to produce positive results. This article describes the application of GDSSs to organizational consultation. The application used a GDSS called Group Systems? to help a group of organizational consultants design prospective consultation interventions for a failing community hospital. Most important, this particular format for collaborative work technology creates an environment in which each participant can express his or her thoughts and experience a sense of co-ownership and responsibility for the development of new understandings. Within the framework of the collaborative model of consultation, these particular outcomes would be listed among the most important. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High‐resolution imaging of nanoparticle bimetallic catalysts supported on mesoporous silica

Although conventional high‐resolution transmission electron microscopy is a powerful method for the elucidation of the structure of mesoporous solids (diameter of pores from 1.5 to 20 nm), it is far less capable than high‐resolution scanning transmission electron microscopy in identifying the spatial distribution of nanocrystals of catalysts encapsulated within the mesopores. Using high‐angle annular dark‐field imaging (either in a 100 or 300 keV STEM system), it is possible to locate precisely individual bimetallic nanoparticles (Ag₃Ru₁₀, Cu₄Ru₁₂ and Pd₆Ru₆ hydrogenation catalysts) supported on mesoporous silica, to determine their size distribution, and to record their characteristic X‐ray emission maps. It is also established that there is little tendency for elemental fragmentation of the bimetallic catalysts, all of which were prepared by decarbonylating, by thermolysis, precursor cluster carbonylate anions: [Ag₃Ru₁₀C₂(CO)₂₈Cl]⁻, [Ru₆C(CO)₁₆Cu₂Cl]²⁻ and [Ru₆Pd₆(CO)₂₄]²⁻. This revised version was published online in July 2006 with corrections to the Cover Date.     

Natural organic matter (NOM) fouling in low pressure membrane filtration — effect of membranes and operation modes

The objective of this study was to evaluate the effects of operating modes, membrane materials and pore size on natural organic matter (NOM) fouling. A range of flat sheet microfiltration (MF) and ultrafiltration (UF) membranes were tested under conditions of various constant pressure and constant flux filtration modes. Based on experimental filtration profiles, molecular weight (MW) distributions of NOM obtained using high performance size exclusion chromatography (HPSEC) and autopsies of fouled membranes using force emission scanning electron microscopy (FESEM), it was concluded that medium to low MW component of NOM (300–1,000 Da) is responsible for the initiation of fouling, where bulk of the fouling observed is due to very high MW ‘colloidal’ NOM (>50,000 Da). This two stage fouling phenomenon was in good agreement with classical blocking laws. As a general observation hydrophilic membranes were less prone to NOM fouling. A comparison of constant pressure and constant flux tests confirmed that modest constant flux, as used in industry, provided the most beneficial conditions.     

Assessment of the “fish tumors or other deformities” beneficial use impairment in brown bullhead (Ameiurus nebulosus): II. Liver neoplasia

Liver pathology of fishes, including neoplastic and preneoplastic lesions, is widely used as an indicator of exposure to anthropogenic contaminants. By definition, the “fish tumor or other deformities” beneficial use impairment (BUI) at Great Lakes Areas of Concern (AOC) includes neoplastic and preneoplastic liver lesions in brown bullhead (Ameiurus nebulosus) or suckers. Unfortunately, adequate guidelines for defining neoplastic and preneoplastic liver lesions or determining rates at unimpacted control sites were not provided and different criteria have been used. In some cases, only neoplastic changes were used to calculate tumor prevalence, in some both neoplastic and preneoplastic changes and in some it is difficult to determine which changes were included. Using standardized criteria, the prevalence of liver neoplasia was compared at eight AOC during 1998–2000. The Cuyahoga River had the highest prevalence (25.0%), while the Maumee River had the lowest (3.9%). The Buffalo (4.8%), Detroit (5.9%), Ashtabula (6.8%), Niagara (7.5%) and Black (8.9%) rivers were intermediate, as was Presque Isle Bay (7.1%). From 2002 to 2007 the prevalence of liver neoplasia at Presque Isle Bay ranged from a low of 2.1% (2002) to a high of 12.0% (2007). Non-AOC sites, as potential reference sites, also were monitored during this time. By combining years and sites, the prevalence of liver neoplasia in bullhead (aged 2 to 12 years) at inland lakes was 0.7%, at bays/harbors was 1.6% and at tributary sites was 4.1%. This is the same trend (inland lakes < bays/harbors < tributaries < Presque Isle Bay) noted for orocutaneous neoplasms.     

Polymer LEDs as a physics tool

We present a systematic experimental and theoretical study of physical mechanisms governing the operation of polymer light-emitting diodes. We show that through self-consistent modeling we can address both charge transport and exciton generation. Electron and hole mobility in several polymers has been characterized experimentally. Characterization of excitons and especially of triplet-excitons is achieved through use of a triplet-emitting molecule.     

SOCIAL: An integrative framework for the development of social skills.

Despite significant advances in the field of social neuroscience, much remains to be understood regarding the development and maintenance of social skills across the life span. Few comprehensive models exist that integrate multidisciplinary perspectives and explain the multitude of factors that influence the emergence and expression of social skills. Here, a developmental biopsychosocial model (SOCIAL) is offered that incorporates the biological underpinnings and socio-cognitive skills that underlie social function (attention/executive function, communication, socio-emotional skills), as well as the internal and external (environmental) factors that mediate these skills. The components of the model are discussed in the context of the social brain network and are supported by evidence from 3 conditions known to affect social functioning (autism spectrum disorders, schizophrenia, and traumatic brain injury). This integrative model is intended to provide a theoretical structure for understanding the origins of social dysfunction and the factors that influence the emergence of social skills through childhood and adolescence in both healthy and clinical populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generation of Internally Mixed Insoluble and Soluble Aerosol Particles to Investigate the Impact of Atmospheric Aging and Heterogeneous Processing on the CCN Activity of Mineral Dust Aerosol

Heterogeneous reactions of trace gases with mineral dust aerosol not only impact the chemical balance of the atmosphere but also the physicochemical properties of the dust particle and the ability of the particle to act as a cloud condensation nuclei (CCN). Recent field studies have shown that carbonate minerals are preferentially associated with nitrates whereas aluminum silicates (i.e., clay minerals) are preferentially associated with sulfates. To better understand how this association can impact the climate effects of mineral dust particles, we have measured the CCN activity of a number of pure and internal mixtures of aerosols relevant to these recent field studies. The CCN activity of CaCO ₃ -Ca(NO ₃ ) ₂ aerosol, simulating the activity of mineral dust aerosol that has been partially processed by nitrogen oxides in the atmosphere, is significantly enhanced relative to CaCO₃ aerosol of the same diameter. Similar results are obtained for a clay mineral, kaolinite, internally mixed with (NH ₄ ) ₂ SO ₄ . For example, at 0.3% supersaturation, a 200 nm particle containing a soluble nitrate or sulfate component is 2 to 4 times more active than an unreacted particle. The results presented here show that when determining the contribution of mineral dust aerosol to the overall impact of the aerosol indirect effect on radiative forcing, changes in chemical composition due to atmospheric processing cannot be ignored.