Eutectic modification and microstructure development in Al-Si alloys

Recent increasing applications for cast Al-Si alloys are particularly driven by the need for lightweighting components in the automotive sector. To improve mechanical properties, elements such as strontium, sodium and antimony can be added to modify the eutectic silicon from coarse and plate-like to fine and fibrous morphology. It is only recently being noticed that the morphological transformation resulting from eutectic modification is also accompanied by other, equally significant, but often unexpected changes. These changes can include a 10-fold increase in the eutectic grain size, redistribution of low-melting point phases and porosity as well as surface finish, consequently leading to variations in casting quality. This paper shows the state-of-the-art in understanding the mechanism of eutectic nucleation and growth in Al-Si alloys, inspecting samples, both quenched and uninterrupted, on the macro, micro and nano-scale. It shows that significant variations in eutectic nucleation and growth dynamics occur in AI-Si alloys as a function of the type and amount of modifier elements added. The key role of AIP particles in nucleating silicon is demonstrated. (c) 2005 Elsevier B.V. All rights reserved.

Effects of process modification and heat pump drying on physical and sensory properties of Chinese style shredded beef

Chinese-style dried, shredded meat is traditionally prepared by sequential cooking, shredding, pre-drying, and final drying (roasting) of lean meat. In this study, shredded dried beef (a(w)<0.6) was prepared by omitting roasting but prolonging pre-drying. Sensory scores of the modified product were lower than those for the traditional product. When heat pump drying replaced traditional oven drying, drying time was shortened without significant difference in quality attributes. Desorption curves were established for shredded beef at several drying temperatures.

Schistosoma mansoni encodes SMT3B and SMT3C molecules responsible for post-translational modification of cellular proteins

The sumoylation pathway is a post-translational modification of nuclear proteins widespread among several organisms. SMT3C is the main protein involved in this process and it is covalently conjugated to a diverse assortment of nuclear protein targets. To date, 3 SUMO paralogues (SMT3C, A/B) have been characterized in mammals and plants. In this work we characterized two SUMO related genes, named SMT3B and SMT3C throughout Schistosoma mansoni life cycle. The SmSMTB/C encodes for proteins sharing significant amino acid homology with SMT3. Phylogenetical analyses revealed that both SmSMT3B/C are distinct proteins. Additionally, SmSMT3B and C are expressed in cercariae, adult worms, eggs and schistosomula however SinSMT3C gene showed an expression level 7 to 9 fold higher than SmSMT3B in eggs, schistosomula and adult worms. The comparison between the SmSMT3C genomic and cDNA sequences established that the encoding sequence is interrupted by 3 introns of 70, 37 and 36 bp. Western Blot has shown SMT3 conjugates are present in nuclear and total protein fractions of adults and cercariae. Therefore our results suggest a functional sumoylation pathway, and the presence of two paralogues also suggests the specificity of substrates for SMT3 in S. mansoni. (c) 2008 Elsevier Ireland Ltd. All rights reserved.

Prevalence of dental wear among 12-year-old Brazilian adolescents using a modification of the tooth wear index

Objective. This study investigated the prevalence of dental wear in 12-year-old adolescents using a modification of the tooth wear index (TWI). The modifications were proposed in order to fit with the World Health Organization standard, thus allowing application of the index in broad epidemiological surveys. Study design: An epidemiological cross-sectional survey was performed by trained, calibrated examiners, using a modified version of the TWI. Methods: Urban elementary schools were chosen because they provide a fair representation of the city`s population in terms of socio-economic status. The sample included 295 adolescents, selected randomly and systematically. Dental wear was assessed by calibrated examiners (kappa > 0.85), using a modified version of the TWI. This modified version includes a code for teeth restored due to wear, and another code for teeth that cannot be assessed. In addition, it does not differentiate the depth of dentine involvement. Proportions and confidence intervals were used to describe the prevalence of dental wear. Mann-Whitney test was used to detect differences in the degree of dental wear between mates and females. The level of statistical significance was set at 5%. Results: In total, 24,780 dental surfaces were evaluated. Among these surfaces, 73.10% did not present dental wear, 24.10% had incipient lesions, 2.46% had moderate lesions and 0.34% had been restored. No severe lesions were detected. Tooth wear was mainly seen on the occlusal/incisal surfaces (26.55%), involving enamel or enamel-dentine, but not the secondary dentine or pulp. The prevalence of dental wear was 26.90%. Considering the different teeth, wear was present in 53.22% of incisors, 50.51% of canines, 10.17% of premolars and 10.85% of molars. The prevalence of the different degrees of dental wear was similar in mates and females (P > 0.05). Conclusion: The modified TWI seems to bean effective toot for use in broad epidemiological surveys, due to easier calibration and high reproducibility rates. (C) 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved.

Hepatocyte [H-3]-palmitate uptake: effect of albumin surface charge modification

The role of plasma proteins on the cellular uptake of lipophilic substrates has perplexed investigators for many years. We tested the hypothesis that an ionic interaction between the protein-ligand complex and hepatocyte surface may be responsible for supplying more ligand to the cell for uptake. The surface-charged groups on albumin were modified to yield proteins having a range of isoelectric points (ALB, ALBs, ALBm, ALBe had values of 4.8-5.0, 4.5-4.7, 3.0-3.5, 8.4-8.6, respectively). [H-3]-Palmitate uptake studies were performed with adult rat hepatocyte suspensions using similar unbound ligand fractions in the presence of the different binding proteins. Mass spectrometry, isoelectric focusing (pI), and heptane : water partitioning were used to determine protein molecular weight, pI, and protein-palmitate equilibrium binding constant, respectively. Hepatocyte [H-3]-palmitate clearance in the presence of ALBs and ALBm were significantly lower (p < 0.05) than ALB, whereas [H-3]-palmitate clearance in the presence of ALBe was significantly higher (p < 0.05) than ALB. The data were consistent with the notion that ionic interactions between extracellular protein-ligand complexes and the hepatocyte surface facilitate the uptake of long-chain fatty acids.

The validity of an Australian modification of the AUDIT questionnaire

The Alcohol Use Disorders Identification Test (AUDIT) has been used widely and is reported to be superior to conventional questionnaires in detection of current hazardous and harmful alcohol use. We assessed the validity of an Australian modification of the AUDIT (the AusAUDIT), which has been employed widely in Australian and New Zealand early intervention programmes. We used a cross-sectional study of 370 subjects from the follow-up phase of a randomized controlled trial of early intervention to reduce hazardous alcohol consumption. Scores on the AusAUDIT were compared against 12-month ICD-10 diagnoses of harmful alcohol use and dependence, as determined by the Composite International Diagnostic Interview, and against self-report of alcohol consumption exceeding Australian National Health and Medical Research Council (NH&MRC) recommended limits. AusAUDIT had good internal consistency and discriminated significantly between persons meeting criteria for ICD-10 alcohol use disorders, and drinkers who did not. At currently recommended cut-off scores, AusAUDIT detected more than 85% of people meeting criteria for ICD-10 alcohol use disorders, or drinking over NH&MRC recommended limits, but its specificity was limited (29% in men, and 58% in women for drinking over NH&MRC limits). No subset of questions performed as well as the full AusAUDIT in detection of drinking problems, but the alcohol consumption items provided a reasonable screen for drinking over NH&MRC limits. We conclude that AusAUDIT is effective in detecting problematic drinking, but positive cases should be confirmed by clinical assessment. The findings illustrate the need for validation of questionnaire modifications, and the difficulty in increasing test sensitivity without reducing specificity.

Wolbachia-mediated sperm modification is dependent on the host genotype in Drosophila

Estimates of Wolbachia density in the eggs, testes and whole flies of drosophilid hosts have been unable to predict the lack of cytoplasmic incompatibility (CI) expression in so-called mod(-) variants. Consequently, the working hypothesis has been that CI expression, although related to Wolbachia density, is also governed by unknown factors that are influenced by both host and bacterial genomes. Here, we compare the behaviour of the mod(-) over-replicating Wolbachia popcorn strain in its native Drosophila melanogaster host to the same strain transinfected into a novel host, namely Drosophila simulans. We report that (i) the popcorn strain is a close relative of other D. melanogaster infections, (ii) the mod(-) status of popcorn in D. melanogaster appears to result from its inability to colonize sperm bundles, (iii) popcorn is present in the bundles in D. simulans and induces strong CI expression, which demonstrates that the bacterial strain does not lack the genetic machinery for inducing CI and that there is host-species-specific control over Wolbachia tissue tropism, and (iv) infection of sperm bundles by the mod(-) D. simulans wCof strain indicates that there are several independent routes by which a strain can be a CI non-expressor.

Long-lasting synaptic modification in the rat hippocampus resulting from NMDA receptor blockade during development

Recent reports have suggested that proper maturation of synapses in the hippocampus requires activation of NMDA receptors. We previously demonstrated that neonatal ethanol exposure results in a lasting reduction in synaptic strength in the hippocampus. To determine if this reduction was due to ethanol's effects on NMDA receptors, we investigated long-term changes in synaptic properties resulting from administration of NMDA receptor antagonists to neonatal animals. Rats were injected daily from PND 4-9 with either the noncompetitive NMDA receptor antagonist MK-801, the competitive NMDA receptor antagonist CPP, or the AMPA receptor antagonist NBQX. Control rats were either injected daily with physiological saline during the same period or left to develop normally. Hippocampal slices were prepared from nembutal-anesthetized animals between PND 35 and PND 40. The maximum pEPSP and PS values were not significantly different between controls and NMDA antagonist-treated animals. However, slices from animals injected with NMDA receptor antagonists required higher stimulus currents to attain comparable pEPSPs. The ratio of the slope of the pEPSP to the amplitude of the presynaptic volley was also reduced, as were pEPSP responses to specific stimulus currents. None of these effects were observed in slices prepared from animals treated with the AMPA receptor antagonist NBQX. Glutamate receptor antagonism did not produce lasting changes in long-term potentiation or paired-pulse facilitation. These results indicate activation of NMDA receptors during development is necessary for proper development of synapses. (C) 2001 Wiley-Liss, Inc.

Phase variable restriction-modification systems in Moraxella catarrhalis

A repetitive DNA motif was used as a marker to identify novel genes in the mucosal pathogen Moraxella catarrhalis. There is a high prevalence of such repetitive motifs in virulence genes that display phase variable expression. Two repeat containing loci were identified using a digoxigenin-labelled 5'-(CAAC)(6)-3' oligonucleotide probe. The repeats are located in the methylase components of two distinct type III restriction-modification (R-M) systems. We suggest that the phase variable nature of these R-M systems indicates that they have an important role in the biology of M. catarrhalis. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.