Interfacial Reactions in Glass–Ceramic-to-Metal Seals

During the sealing of glass–ceramics to metals, undesirable interfacial reactions may occur between constituents of the glass and diffusing metal species, and any reaction products formed may have serious consequences on the lifetime behavior of seal components. This paper reviews the factors influencing the lifetime behavior of glass–ceramic-to-metal systems, with particular emphasis given to the effect that such interfacial reactions can have on the resultant and longer term properties. Steps that can be taken to enhance desirable interfacial reactions and minimize those that are undesirable are highlighted. In addition, in order to aid in the understanding of complex alloy systems, it is of interest to study both the interfacial reactions and diffusion characteristics of simplified systems without the complicating issue of multiple element diffusion. Thus, a preliminary investigation is highlighted in which a lithium zinc silicate glass nucleated with P₂O₅ has been sealed to high-purity Fe, Ni, and Cr metals and the resultant diffusion into the glass of each metal monitored as a function of sealing temperature and time. The data generated have been compared with information from multicomponent alloy systems and an attempt has been made to explain the differences noted.     

External knee support in rugby union. Effectiveness of bracing and taping

Ozone (O3) is a controversial gas because, owing to its potent oxidant properties, it exerts damaging effects on the respiratory tract and yet it has been used for four decades as a therapy. While the disinfectant activity of O3 is understandable, it is less clear how other biological effects can be elicited in human blood with practically no toxicity. On the other hand plasma and cells are endowed with a powerful antioxidant system so that a fairly wide range of O3 concentrations between 40 and 80 microg/ml per gram of blood (approximately 0.83-1.66 mM) are effective but not deleterious. After blood ozonation total antioxidant status (TAS) and plasma protein thiol groups (PTG) decrease by 20% and 25%, respectively, while thiobarbituric acid reactive substances (TBARS) increases up to five-fold. The increase of haemolysis is negligible suggesting that the erythrocyte membrane is spared at the expense of other sacrificial substrates. While there is a clear relationship between the ozone dose and IL-8 levels, we have noticed that high TAS and PTG values inhibit the cytokine production. This is in line with the current idea that hydrogen peroxide, as a byproduct of O3 decomposition, acts as a messenger for the cytokine induction.     

Ascorbic acid-based inhibitors of alpha-amylases

A series of ascorbic acid and isoascorbic acid derivatives has been evaluated as inhibitors of malt, bacterial, fungal, pancreatic and salivary alpha-amylases using a simple and quick assay procedure. The results demonstrate that the enediol moiety of ascorbic acid is essential for alpha-amylase inhibition. Acylation of the primary and secondary alcohols, and the absolute configuration of the secondary alcohol, do not affect the potency of inhibition.     

Solubilization of Aromatic Hydrocarbons in Ethylene Oxide-Propylene Oxide Triblock Micelles: Location of Solubilizate and its Effect on Micelle Size from 2D NMR and Scattering Techniques

The solubilization of benzene and toluene in micellar solutions and the effects on the micellization and micelle size of ethylene oxide-propylene oxide triblock copolymers were investigated by dynamic light scattering (DLS), small angle neutron scattering (SANS), and 2D NMR spectroscopy. The copolymeric surfactants have the same size as the middle hydrophobic polypropylene oxide block (Mol. Wt. 3250) and varying polyethylene oxide end blocks (30, 40 and 50%). The solubilization and the properties of the micelles in the presence of the solubilizates were investigated; the results reveal that the more hydrophobic copolymer showed better solubilization. The cloud points of the copolymers decreased in the presence of oils; the depression in the cloud point is due to the formation of an electron donor–acceptor complex. DLS shows that the effect of benzene is dominated at high oil concentration. SANS data show that the micelles remain spherical in shape and that the micellar core size does not change with higher benzene concentration; observed changes in the low scattering vector region could be because of some small amount of benzene clusters formed at higher benzene concentration. Finally, the locus of solubilization of the oils in the copolymer micelles was determined via 2D NMR experiments. In all cases, significant nuclear Overhauser effect spectroscopy (NOESY) cross peaks were observed that appeared to correlate well with the expected loci of these solubilizates in micelles. Hence, the noninvasive NOESY technique provides important information on the location of the aromatic solubilizates in these copolymer micelles that depends on the structure of the oils.     

Understanding the corrosion behaviour of the magnesium alloys EV31A,WE43B,and ZE41A

The corrosion rates of the Mg alloys immersed in 3.5 wt% NaCl solution saturated with Mg(OH)₂ were in the following increasing order: WE43B (0.23 mm/y) < EV31A (0.88 mm/y) < pure‐Mg (1.6 mm/y) < ZE41A (8.5 mm/y). The average corrosion rate for WE43B was somewhat lower than the intrinsic corrosion rate of Mg as shown by high‐purity Mg, attributed to (a) no corrosion acceleration by the small second phase particles, and (b) a more protective surface film. The high corrosion rates of ZE41A were attributed to the presence of a coarse semicontinuous T‐phase, which served as strong cathodic sites.     

The Strong African American Families Program: Prevention of youths' high-risk behavior and a test of a model of change.

In this study, the efficacy of the Strong African American Families Program (SAAF) was tested. The trial, which included 332 families, indicated that families who participated in SAAF experienced increases over time in regulated, communicative parenting; increases in targeted parenting behaviors, according to youths' reports; and low rates of high-risk behavior initiation among youths. Changes in regulated, communicative parenting mediated the intervention's impact on youths' recognition of changes in parenting, which in turn was linked to changes in youths' high-risk behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of Maillard cross-linking on soy proteins and tofu texture

In this paper, we explore the use of Maillard cross-linking agents (formaldehyde, glyceraldehyde and glutaraldehyde) in tofu, to probe the relationship between cross-linking of soy proteins and tofu texture. 1–2 mM glutaraldehyde treatment resulted in an acceptable product with altered microstructure. At 2 mM glutaraldehyde, the fracture force was increased if the reagent was added before soymilk boiling, but decreased if it was added after boiling, when more cross-linking was observed due to the denaturation of the proteins. The fracture forces and microstructures are hard to rationalise in terms of cross-linking, suggesting that other factors, such as non-cross-linking protein glycation, may be responsible for the observed changes. Taken together with the results reported in the previous paper, these findings suggest that protein cross-linking agents may change the functional properties of tofu via non-cross-linking modifications of the sidechains of the amino acid residues, changing their isoelectric point and their gelation properties.     

Prevalence estimates and adolescent risk behavior: Cross-cultural differences in social influence.

Prevalence estimates and prototype perceptions related to health risk behaviors were assessed in comparable samples of Danish and American adolescents (ages 13–15 years). Partly on the basis of observation and previous research, the assumption was made that the American sample would report more self-enhancement tendencies than would the Danish sample. Consistent with this assumption, which was supported by the data, 2 hypotheses were tested: (a) The Americans would overestimate the prevalence of the various risk behaviors (among their peers) more so than would the Danes and (b) those estimates would be more closely linked to their own risk behaviors for the American sample. Results supported both hypotheses; motivational explanations were proposed for both effects. In addition, perceptions of the prototypes associated with particular risk behaviors were assessed and were found to predict smoking behavior and willingness to engage in unprotected sexual intercourse for both samples. Implications for the study of adolescent risk behavior are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

From top dog to bottom half: Social comparison strategies in response to poor performance.

Although the hypothesis that people will alter comparison behavior in response to threat is consistent with the formulation of social comparison theory, the empirical evidence for the natural occurrence of such shifts is weak. Two studies were conducted to examine this hypothesis. In the 1st study, adolescents' perceptions were assessed before, during, and 6 mo after their participation in an academic program for gifted students. Male students who performed poorly, and also worse than they had expected in the program, demonstrated self-protective strategies by lowering the amount and level of academic comparison they reported engaging in and by lowering their perception of the importance of academics. Female students, who generally performed as well as expected, reported relatively little change. By follow-up, most of the male students' perceptions had returned to baseline. A 2nd study found that both male and female college students who thought they had performed poorly academically also demonstrated these shifts in comparison. Motivations behind the strategies are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)