Studies on sodium silicate solutions by the method of trimethylsilylation

The method of trimethylsilylation was used to study anion distributions in sodium silicate solutions with Na₂O: SiO₂ ratios of 1:1 and 1:3.41 at various concentrations. The polysiloxanes produced were characterised, mainly by g.l.c., g.p.c. and C and H analyses, to give a picture of the anion distribution in the original solution. The results were compared with those from previous studies. The observations of earlier workers—that the degree of polymerisation increases with increasing concentration and decreasing soda:silica ratio—were confirmed.     

The influence of microwave heating on the morphology and benzene hydrogenation activity of alumina- and silica-supported palladium catalysts

Alumina- and silica-supported palladium catalysts were prepared by conventional and microwave heating. The catalysts have been characterized by nitrogen adsorption, hydrogen chemisorption, X-ray powder diffraction and temperature-programmed reduction and tested for benzene hydrogenation activity. The results show that preparation of samples by microwave heating leads to enhanced crystallite size and increased hydrogenation activity.     

Children's distributive justice reasoning: A standardized and objective scale.

A paired-comparisons measure of distributive justice development (DJS) was developed and validated in 3 studies. In Exp I, 104 children from kindergarten and 2nd and 4th grades were given the DJS and 2 Piagetian logical reasoning tasks. Age trends and a relation with logical reasoning were found. In Exp II, 66 1st, 3rd, and 5th graders were given the DJS and a measure of verbal ability. Age trends and a low relation with verbal ability were found. In Exp III, 88 1st, 3rd, and 5th graders from Kinshasa, Zaire, were given the DJS. The trends replicated those found in Exp II. Implications for distributive justice research are drawn. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning support environments: Rationale and evaluation

In this paper we argue that existing understanding of human cognition has much to offer the design of instructional systems and materials, and that new technologies, such as hypertext, in harness with traditional techniques, provide opportunities for extending the mapping of cognitive principles to instructional design. Following a review of types of knowledge, cognitive styles and strategies within a CAL framework, the advantages of learning support environments over other CAL approaches are discussed. Such environments are presented as extensions to hypertext which incorporate various generic features for learning applications. The need for evaluation of learning which is dynamic and internal to the learning tasks is stressed.     

IL-12, but not IFN-gamma, plays a major role in sustaining the chronic phase of colitis in IL-10-deficient mice

IL-10-deficient (IL-10(-/-)) mice develop chronic enterocolitis mediated by CD4+ Th1 cells producing IFN-gamma. Because IL-12 can promote Th1 development and IFN-gamma production, the ability of neutralizing anti-IL-12 mAb to modulate colitis in IL-10(-/-) mice was investigated. Anti-IL-12 mAb treatment completely prevented disease development in young IL-10(-/-) mice. Treatment of adult mice resulted in significant amelioration of established disease accompanied by reduced numbers of mesenteric lymph node and colonic CD4+ T cells and of mesenteric lymph node T cells spontaneously producing IFN-gamma. In contrast, anti-IFN-gamma mAb had minimal effect on disease reversal, despite a significant preventative effect in young mice. These findings suggested that IL-12 sustains colitis by supporting the expansion of differentiated Th1 cells that mediate disease independently of their IFN-gamma production. This conclusion was supported by the finding that anti-IL-12 mAb greatly diminished the ability of a limited number of CD4+ T cells expressing high levels of CD45RB from diseased IL-10(-/-) mice to expand and cause colitis in recombination-activating gene-2(-/-) recipients, while anti-IFN-gamma mAb had no effect. Furthermore, IL-12 could support pathogenic IL-10(-/-) T cells stimulated in vitro in the absence of IL-2. While these studies show that IL-12 plays an important role in sustaining activated Th1 cells during the chronic phase of disease, the inability of anti-IL-12 mAb to abolish established colitis or completely prevent disease transfer by Thl cells suggests that additional factors contribute to disease maintenance.     

Between hard and soft HRM: human resource management in the construction industry

The rapid change in the economic environment has not resulted in the development of sophisticated human resource management practices in the UK construction industry. There are similarities between personnel practice in construction and ‘hard’ models of HRM, particularly in relation to manual workers, but non-manual employment resembles more the conditions where ‘soft’ HRM might be expected. Focusing on the HRM levers developed by John Storey, HRM practices are examined in relation to the role of personnel departments, line management responsibility, performance management, and values and beliefs of personnel managers. The survey results suggest few signs of fundamental or far-reaching innovation in human resource management practice in the construction industry despite the changing shape of construction companies. There are some, though limited, signs of change in respect to expectations of training and employee development in the future.     

Impaired fear memories are correlated with subregion-specific deficits in hippocampal and amygdalar LTP.

Inbred mouse strains have different genetic backgrounds that likely influence memory and long-term potentiation (LTP). LTP, a form of synaptic plasticity, is a candidate cellular mechanism for some forms of learning and memory. Strains with impaired fear memory may have selective LTP deficits in different hippocampal subregions or in the amygdala. The authors assessed fear memory in 4 inbred strains: C57BL/6NCrlBR (B6), 129S1/SvImJ (129), C3H/HeJ (C3H), and DBA/2J (D2). The authors also measured LTP in the hippocampal Schaeffer collateral (SC) and medial perforant pathways (MPP) and in the basolateral amygdala. Contextual and cued fear memory, and SC and amygdalar LTP, were intact in B6 and 129, but all were impaired in C3H and D2. MPP LTP was similar in all 4 strains. Thus, SC, but not MPP, LTP correlates with hippocampus-dependent contextual memory expression, and amygdalar LTP correlates with amygdala-dependent cued memory expression, in these inbred strains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)