Microstructure Evolution and Tensile Properties of a Selectively Laser Melted CoNi-Base Superalloy

Metallurgical and Materials Transactions A - A high $$\gamma ^{\prime }$$ volume fraction CoNi-base superalloy with roughly equal amounts of cobalt and nickel was successfully processed through...     

Acute effects of nicotine content in cigarettes on coronary flow velocity and coronary flow reserve in men

We investigated the acute effects of smoking on coronary flow reserve in terms of the nicotine content of cigarettes in 21 smokers. Coronary flow velocity was measured with a Doppler flow wire. Subjects smoked cigarettes containing >1 mg nicotine (n = 8, group 1) or <1 mg (n = 6, group 2). Subjects in the control group mimicked smoking without a cigarette (n = 7). Coronary flow reserve decreased after smoking in group 1, but not in group 2 or the control group. This reduction may have mediated nicotine or some other unknown substances influenced by smoking.     

Identification of a phosphopantetheinyl transferase for erythromycin biosynthesis in Saccharopolyspora erythraea

Phosphopantetheinyl transferases (PPTases) catalyze the essential post-translational activation of carrier proteins (CPs) from fatty acid synthases (FASs) (primary metabolism), polyketide synthases (PKSs), and non-ribosomal polypeptide synthetases (NRPSs) (secondary metabolism). Bacteria typically harbor one PPTase specific for CPs of primary metabolism ("ACPS-type" PPTases) and at least one capable of modifying carrier proteins involved in secondary metabolism ("Sfp-type" PPTases). In order to identify the PPTase(s) associated with erythromycin biosynthesis in Saccharopolyspora erythraea, we have used the genome sequence of this organism to identify, clone, and express (in Escherichia coli) three candidate PPTases: an ACPS-type PPTase (S. erythraea ACPS) and two Sfp-type PPTases (a discrete enzyme (SePptII) and another that is integrated into a modular PKS subunit (SePptI)). In vitro analysis of these recombinant PPTases, with an acyl carrier protein-thioesterase (ACP-TE) didomain from the erythromycin PKS as substrate, revealed that only SePptII is active in phosphopantetheinyl transfer with this substrate. SePptII was also shown to provide complete modification of ACP-TE and of an entire multienzyme subunit from the erythromycin PKS in E. coli. The efficiency of the SePptII in phosphopantetheinyl transfer in E. coli makes it an attractive alternative to other Sfp-type PPTases for co-expression experiments with PKS proteins.     

Polyketide biosynthesis: understanding and exploiting modularity

Polyketide-based pharmaceuticals are some of our most important medicines. They are constructed in micro-organisms (typically bacteria and fungi) by gigantic enzyme catalysts called polyketide synthases (PKSs). The organization of PKSs into molecular assembly lines makes them particularly appealing targets for genetic engineering because, in principle, an alteration in the enzyme organization might translate into a predictable change in polyketide structure. Excitingly, this has been shown repeatedly to work in practice, but the efficiency of the engineered PKSs is frequently too low to be useful for large-scale drug synthesis. To reach this goal, researchers need a deeper understanding of the structure and function of these proteins, which are among the most complex in nature. This review highlights some recent experiments which are providing key information about the molecular organization, mechanism and orchestration of these magnificent catalysts, and opening up fresh prospects of truly combinatorial biosynthesis of novel polyketides as leads in drug discovery.     

Exploring dimensions to online learning

The study presented in this paper sought to explore several dimensions to online learning. Identifying the dimensions to online learning entails important basic issues which are of great relevance to educators today. The primary question is “what are the factors that contribute to the success/failure of online learning?” In order to answer this question, we need to identify the important variables that: (1) measure the learning outcome and (2) help us understand the learning experience of students using specific learning tools. In this study, the dimensions we explored are student’s attitude, affect, motivation and perception of an Online Learning Tool usage. A survey methodology was used such that validated items from previous relevant research work were adopted. 105 students completed the questionnaire. An exploratory factor analysis (EFA) was implemented on the data captured. Results of the EFA identified the items that are relevant to the present context and the items that can be used to measure the dimension to online learning. Affect and perception were found to have strong measurement capabilities with the adopted items while motivation was measured the weakest.     

Relationship quality profiles and well-being among married adults.

The marital relationship rarely exists in isolation and yet few studies have examined the multiple relationships experienced by most married people. This study used the Convoy Model of Social Relations to examine patterns of multiple relationships and well-being among men and women ages 22 to 79 years (N = 654). Cluster analyses identified profiles of relationship quality among people with spouse, family (children, mother, father), and a best friend (N = 451) and those married with family but no best friend (N = 202). Relationship profiles differed in quality and by gender, race, and age. Among people with best friends, having at least 2 high quality relations, not necessarily with a spouse, is associated with greater well-being. In contrast, among people without best friends, the spousal relation appears to be particularly important for well-being. Although family relationships (e.g., spouse) are important for well-being, interventions should consider the composition and quality of social networks to determine which relationships may need improvement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of putative gene encoded on ORF16 of the 81 kb contig of Arabidopsis thaliana chromosome III as alpha-mannosidase

We isolated cDNA corresponding to open reading frame (ORF) 16 of the 81 kb contig of Arabidopsis thaliana chromosome III [Quigley., Nucleic Acids Res., 24, 4313-4318 (1996)] and expressed alpha-mannosidase activity in tobacco suspension-cultured cells, which revealed that ORF16 encodes alpha-mannosidase. We also suggested that Arabidopsis harbors three genes encoding alpha-mannosidase by homology search against the database.     

A specific decision support system (SDSS) to develop an optimalproject portfolio mix under uncertainty

A specific decision support system (SDSS) than can be used as a methodology for choosing an optimal portfolio mix of information systems projects is described. The SDSS is developed by applying a number of well-known management science techniques. A net present value (NPV) of the projects is maximized within limited resources, and the solution of the model provides the optimal project start period, system development language, and staff size. The SDSS conducts a risk analysis on those variables that are deemed critical when determining the optimal solution. The final phase of the SDSS establishes the value of perfect information on these critical variables. To demonstrate the usefulness of the model an example consisting of five information system (IS) projects is presented. It is shown that, given the estimates of the exogenous parameters of the IS project environment, the model can determine when to begin the project development, which systems development language to use, and the number of systems development staff assign to each project. The degree of the variability of the estimates of exogenous parameters is evaluated through empirical probability distributions