Small‐angle neutron scattering of poly(styrene)/poly(acrylic acid–ethyl acrylate) copolymers: The effect of the degree of hydrolysis of the poly(acrylic acid–ethyl acrylate) block

We report the results of systems based on polystyrene‐poly(ethyl acrylate) (PEA) diblocks, which self‐assemble in aqueous solutions to form spherical micelles. Previous work has shown that the rheological properties of these solutions, in particular the gel–liquid transition, can be tuned through the use of a simple hydrolysis reaction to convert PEA to poly(acrylic acid) (PAA). We studied the effect of the extent of hydrolysis on the self‐assembly and micellar interactions. Small‐angle neutron scattering (SANS) spectra were fit with a variety of models to determine the micelle structure. As more PEA was converted to PAA (i.e., as the corona became more charged and more hydrophilic), the micellar aggregation number decreased, analogous to observations of other polymeric micelles. This effect could impact the gel–liquid transition and rheology in this system and in similar micellar block copolymer gels. Finally, our SANS spectra qualitatively agreed with predictions for attractive colloidal glasses, confirming the idea that the elasticity of these gels arises from the jamming of micelles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 490–497, 2004     

Public Employee Pension Funds and Social Investments: Recent Performance and a Policy Option for Changing Investment Strategies

Abstract: Public employee pension funds have emerged as major sources of investment dollars for real estate development. The size of these funds has prompted periodic, but intense, interest in diverting some portion of the resources controlled by fund managers into socially desired investments. While there is a wide range of possible investments that could be classified as socially desirable, a commitment of a portion of the available resources to the redevelopment of metropolitan areas could have an important impact on deteriorating communities and areas that have struggled to attract resources from other investors. This article looks at the issue of social investing, past assessments of the investment strategies of pension funds, and then analyzes the real estate investments made by a group of large public employee pension funds in different states. In noting that the support for redeveloping deteriorating areas is, unfortunately, still lagging, a policy option is presented to increase the level of performance and measure its success.     

The Gulf of Mexico Decommissioning Market

The Gulf of Mexico offshore decommissioning market is the most diverse and competitive service contract environment in the world. The purpose of this paper is to describe the business, engineering, and market environment of decommissioning services in the Gulf of Mexico, and to provide a first-order approximation of the number of structures expected to be removed over a 25 year time horizon. Decommissioning activities associated with offshore production are an important and specialized segment of marine construction that has received limited attention in the academic literature, yet is compelling because few industrial sectors have such well-understood and widely adopted abandonment requirements. This paper should appeal to practitioners and researchers interested in learning the processes involved in deconstruction and the basic structure of the industry. The regulatory requirements and primary stages of decommissioning are reviewed, and the management, bid/tender process, and negotiation strategies are described. A life expectancy model of the number of structures expected to be removed from the Gulf of Mexico is presented, along with a discussion of the model uncertainty and the limitations of the analysis.     

Mechanistic understanding of the fermentative L‐glutamic acid overproduction by Corynebacterium glutamicum through combined metabolic flux profiling and transmembrane transport characteristics

Since the 1950s when Micrococcus glutamicus later renamed Corynebacterium glutamicum was discovered, the production of amino acids by fermentative methods has become an important aspect of industrial microbiology. Numerous studies to understand and improve the metabolic conditions leading to amino acid overproduction have been carried out. Most amino acids are currently produced by use of mutants that contain combinations of auxotrophic and regulatory mutations. L ‐Glutamic acid is the amino acid produced in the greatest quantities (10⁶ tonnes per year) and Corynebacteria are central to its industrial production. However, further improvements to strain performance are difficult to obtain by empirical optimization and a more rational approach is required. The use of metabolic flux analysis provides valuable information regarding bottlenecks in the formation of desired metabolites. Such techniques have found application in elucidating flux control, provided insight into metabolic network function and developed methods to amplify or redirect fluxes in engineered bioprocesses. Hence, branch points in biosynthesis, precursor supply in fuelling reactions and export of metabolites can be manipulated, resulting in high glutamic acid overproduction by Corynebacterium glutamicum fermentations. In this review, in addition to reviewing the state of play in metabolic flux analysis for glutamate overproduction, the metabolic pathways involved in the production of L ‐glutamic acid, the mechanisms mediating its efflux and secretion as well as their manipulation to achieve higher glutamate production, are discussed. The link between metabolic flux and transmembrane transport of glutamic acid are also considered. Copyright © 2004 Society of Chemical Industry     

Hydrolytic Condensation of Tin(IV) Alkoxide Compounds to Form Particles with Well-Defined Morphology

The sol-gel-type condensation of tin(IV) ethoxide [Sn(OEt)₄] n (where OEt is ethoxide) under basic conditions produced spherical, submicrometer-sized tin(IV) oxide (cassiterite) particles. Transmission electron microscopy and powder X-ray diffraction data indicated that the grain size was approximately 20 to 30 Å (2 to 3 nm). The mixed-metal alkoxide compound [ZnSn(OEt)₆] was hydrolyzed under analogous conditions to give either spherical or octahedral submicrometer-sized crystalline particles of ZnSn(OH)₆ depending on the solvents used. These data demonstrated that the stoichiometry of the mixed-metal alkoxide precursor was retained during condensation. Thermal treatment of ZnSn(OH)₆ resulted in crystallization of ZnSnO₃ at approximately 676°C. At neutral pH, hydrolysis of [ZnSn(OEt)₆] resulted in formation of a high surface area (261 m²/g) amorphous powder.     

Depression and social problem solving.

20 depressed patients with major depressive disorder, 20 nondepressed matched control Ss, and 17 patients with anxiety disorders were compared in different measures of social problem solving. Problem solving was assessed with the Means-Ends Problem-Solving Test (Study 1), the solution of personal problems, and a problem-solving questionnaire (Study 2). Results showed that, as predicted, depressed Ss suffered from a deficit in problem solving in all 3 measures. The majority of these deficits were also displayed by the clinical control group rather than being specific to a diagnosis of depression. However, depressed Ss produced less effective solutions than did normal and clinical control Ss. The results suggest that depressed and anxious patients may have difficulties at different stages of the problem-solving process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)