Cell biology of hydrogels

This paper demonstrates the hydrophilic polymers (mainly based on hydroxyethyl methacrylate) as a tool of cell biology. They represent a favourable model for the study of the influence of the molecular design of polymers on (1) bioactive protein adsorption, (2) cell adhesion and/or (3) control of their function. The influence of the hydrophilic/hydrophobic properties of polymers and of the occurrence of charged functional chemical groups is able to influence the interaction of cells with these polymers. For example, the copolymer of hydroxyethyl methacrylate with sodium methacrylate (-COO- groups) is only little recognized by macrophages, which could be used in clinical implantology. It is shown that, similar to natural macromolecules of the extracellular matrix, the synthetic polymers are able to participate in the control of cell function.     

Randomized residual-based error estimators for the proper generalized decomposition approximation of parametrized problems

This article introduces a novel error estimator for the proper generalized decomposition (PGD) approximation of parametrized equations. The estimator is intrinsically random: it builds on concentration inequalities of Gaussian maps and an adjoint problem with random right-hand side, which we approximate using the PGD. The effectivity of this randomized error estimator can be arbitrarily close to unity with high probability, allowing the estimation of the error with respect to any user-defined norm as well as the error in some quantity of interest. The performance of the error estimator is demonstrated and compared with some existing error estimators for the PGD for a parametrized time-harmonic elastodynamics problem and the parametrized equations of linear elasticity with a high-dimensional parameter space.     

How much do I tell thee? Strategies for managing information to parents among American adolescents from Chinese, Mexican, and European backgrounds.

Strategies for managing information about activities to parents, including partial disclosure, avoidance, lying, and full disclosure, were examined in 479 American adolescents (M = 16.38 years, SD = 0.77) varying in generational status and from Mexican, Chinese, and European backgrounds. Information management strategies for personal, prudential, and overlapping (multifaceted) activities as defined within social domain theory were examined. With age, parental education, and generational status controlled, Chinese American adolescents partially disclosed more to mothers about personal and multifaceted activities than did Mexican American adolescents and more to fathers about personal activities than did European American teens. In contrast, European and Mexican American adolescents fully disclosed more to mothers about personal activities than did Chinese-origin adolescents. Strategies varied by generation among Chinese American youth; second-generation adolescents avoided discussing activities with parents more than did immigrants. Adolescents who fully disclosed about all activities and lied less about multifaceted and personal activities reported stronger endorsement of obligations to assist their families, more trust in parents, and less problem behavior. More depressed mood was associated with more lying about personal activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A cross-cultural comparison about what? A critique of Nisan's (1987) study of morality and convention.

This critique of Nisan's (1987) study of morality and convention addresses methodological considerations for cross-cultural research on children's moral and conventional concepts. Three methodological structures for research on children's conceptual differentiations of societal and moral issues are outlined. One is the use of moral and conventional issues familiar to children. A second is that questions regarding rules or authority should be couched in relevant concrete contexts. The third is that there should be ways of testing the limits of perceived appropriateness of a rule or of the jurisdiction of authorities. The Nisan study was found to be deficient in its application of all three criteria. Other limitations of the Nisan study are also addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Theory of Tin Whisker Growth: “The End Game”

Previous theories of the tin whisker growth proposing various dislocation mechanisms have been largely disproved. This paper presents a new and different theory for the mechanism of tin whisker growth. The theory addresses the fundamental requirements for Sn to diffuse to the base of the whisker grain and proposes a mechanism for whisker initiation and growth. Part of this is a theoretical proposal as to what makes the whisker grain different. The role of oxidation in whisker growth is also briefly addressed. Using this theory, attempts are made to illustrate how different whisker shapes are created. Finally, a proposed potential solution to tin whisker growth is presented, assuming that this theory is correct     

Microvoid Formation at Solder–Copper Interfaces During Annealing: a Systematic Study of the Root Cause

The electrodeposition conditions that contribute to microvoid formation during isothermal aging of Pb-free solder-electrodeposited copper were evaluated in a systematic series of processing experiments. The results of 2 ^K full-factorial design of experiment are presented to show the effect of prescreened electroplating parameters such as brighteners, wetting agent, bath age, and current density on the propensity for microvoiding at solder–copper interfaces after annealing at 125°C for 40 days. It was found that the amount of microvoiding is greatly affected by bath age, wetting agent, brightener, and their interactions. Time-of-flight secondary-ion mass spectroscopy and glow discharge spectroscopy allowed us to establish a correlation between impurities incorporated in copper during electroplating and microvoiding at the solder–copper interface.     

Processing procedures for the realization of fine structured channel arrays and bridging elements by LTCC-Technology

This report deals with technological procedures to provide channel partition walls of minimum width inside of Low Temperature Co-fired Ceramics (LTCC) micro fluidic devices demonstrated by means of the fabrication of parallel closely-spaced channels which may act as a specific functional part of a fluidic heat exchanger. Furthermore, the realization of single layer bridging elements inside of channels is discussed. Such an element may be introduced as a delicate sensor substrate providing adequate thermal insulation and low thermal mass as well. The technological processing steps under consideration start with laser micromachining of green ceramic tapes using Nd-YAG-laser equipment and are followed by a modified low-pressure lamination step comprising the application of appropriate adhesives and the incorporation of polymer sacrificial volume materials (SVMs). Consequently, the increased fraction of involved organics requires an adequate adaptation of the firing process to provide a residue-free burnout. Great attention is paid to the prevention of channel cross-section distortion and to the integrity of structures, verified by optical inspection of microsectioned samples. The optimized processing procedures enable the fabrication of channel arrays with a partition wall thickness as small as 100 μm, while single layer bridging elements may span a channel width of 4 mm.     

Identification of fibronectin in tissue implant interfaces

This study demonstrates the presence of fibronectin in cells and extracellular deposits on the surface of a cellophane implant nine days after surgery. The mononuclear cells with epithelioid or fibroblastoid morphology were positive for fibronectin. A small quantity of this fibronectin contained fibrillar network-like extracellular deposits, which are typical of fibroblasts. Multinucleate foreign-body giant cells were only poorly positive for fibronectin. These results indicate the prevalence of macrophages on the surface of cellophane implants, contrasting with the low incidence of fibroblasts.     

Biological and biochemical properties of the carbon composite and polyethylene implant materials

We studied the biocompatibility of the carbon composites and polyethylene materials with and without collagen or collagen and proteoglycan cover. We used the in vitro technology to study the adhesion of model cells evalution, their metabolic activity and the production of TNF- as a cytokine model. Under in vivo condition, the biocompatibility of tested polymers were studied in the implantation experiment, subcutaneously in the interscapular region in the laboratory rat. We have found in the in vitro assay favorable proliferation and the smallest production of pro-inflammatory TNF- cytokine in cells adherent to the hydrophobic polyethylene material coated with biological macromolecules. Using in vivo tests performed by the implantation of materials to the rat we demonstrated that the materials are not cytotoxic. The tissue capsule surrounding the implants was not significantly influenced by the type of the implant and the pre-treatment by the biological molecules. However, the foreign-body giant multinucleated cells were observed only in the vicinity of the collagen – covered hydrophobic polyethylene implant. Interestingly, while the collagen coating improved the biocompatibility of tested polymers in vitro, the inflammatory reaction against this covered materials was higher under in vivo conditions. The pre-treatment of carbon composites by both types of biological macromolecules reduced the occurrence of carbon debris in the implantation site. The tested carbon composites and polyethylene materials are not toxic. The pre-treatment of the materials by extracelular matrix components increased their biological tolerance in vitro and reduced implant wears in animal experiment, which can be important for the medical application.