Spatially resolved evolution of adhesion properties of large porcelain tiles

The rising number of failures of porcelain tiles, especially in outdoor applications, is to some extent a consequence of the critical combination of applying tiles of large dimensions and the non-porous nature of these tiles. A special setup allows a reproducible application of large-sized tiles (30 × 30 cm). In analogy to outdoor conditions, samples were stored under dry and wet conditions and have been investigated with different physico-chemical approaches. Under dry storage conditions adhesion strength is significantly lower along the periphery of the tiles compared to their centre. This reduction in adhesion performance is mainly caused by shrinkage of the mortar and substrate (～0.1 mm/m). In situ observations through glass tiles indicate that the stresses induced by shrinkage are highest in the rim regions of the tiles. Under wet storage conditions, water percolates into the rim regions of the mortar, which leads to swelling of mortar and substrate, accelerating the delamination process. The findings of this study confirm observations on the construction site, where initial failures are often found at the periphery of large-sized tiles.     

Determinants of persistence in canine distemper viruses

The history of immunohistochemistry started in 1941 when Coons identified pneumococci using a direct fluorescent method. Then followed the indirect method, the addition of horseradish peroxidase, the peroxidase anti-peroxidase technique of 1979 and the use of the Avidin and Biotin complex in the early 1980s. This sequence of events can help one appreciate the differences in these various techniques and their increased sophistication and sensitivity. The technique has been applied in the field of safety evaluation of new pharmaceutical products. Examples of current projects are used to illustrate the scope of the application. The use of an antibody to detect proliferating cell nuclear antigen has, in a pilot study with the popliteal lymph node assay, provided a method of differentiating an irritant response to acetone from an immune response to hydrazine. In hydrazine-treated rats the proliferation is mainly in the follicular region whilst it is mainly sinusoidal in animals treated with acetone. In the guinea-pig maximisation test, initial work with dinitrochlorobenzene suggests that detection of Langerhans cells may aid the differentiation of an irritant from an immune response. The preclinical assessment of antibodies intended for therapeutic use in man requires immunohistochemistry to be used to identify any human tissues which show a cross-reactivity. The major problems are not in the test itself but in obtaining suitable material. Identification of hormones is a useful tool for assessing the effects of releasing factors and has proved useful in aiding tumour identification in routine carcinogenicity studies. In a rare case, detection of prolactin in cell deposits in the lungs of a rat confirmed that this was a metastasis from a pituitary carcinoma. The application of immunohistochemical techniques to preclinical assessment of drugs should always be considered. In particular, it is recommended that appropriate samples should be conserved from routine studies in order to permit these techniques to be performed, if considered appropriate in the light of findings during routine histological examination.     

Phytochrome‐Based Extracellular Matrix with Reversibly Tunable Mechanical Properties

Interrogation and control of cellular fate and function using optogenetics is providing revolutionary insights into biology. Optogenetic control of cells is achieved by coupling genetically encoded photoreceptors to cellular effectors and enables unprecedented spatiotemporal control of signaling processes. Here, a fast and reversibly switchable photoreceptor is used to tune the mechanical properties of polymer materials in a fully reversible, wavelength‐specific, and dose‐ and space‐controlled manner. By integrating engineered cyanobacterial phytochrome 1 into a poly(ethylene glycol) matrix, hydrogel materials responsive to light in the cell‐compatible red/far‐red spectrum are synthesized. These materials are applied to study in human mesenchymal stem cells how different mechanosignaling pathways respond to changing mechanical environments and to control the migration of primary immune cells in 3D. This optogenetics‐inspired matrix allows fundamental questions of how cells react to dynamic mechanical environments to be addressed. Further, remote control of such matrices can create new opportunities for tissue engineering or provide a basis for optically stimulated drug depots.     

外墙彩色砂浆的泛碱问题

在干混砂浆工业中．泛碱造成水泥基材料褪色而影响美观性的现象是一个大家普遍关心的问题．泛碱是由于盐分沉积在矿物建筑材料如混凝土．砂浆或砖墙的表面引起的．目前．泛碱对于装饰砂浆如彩色抹灰砂浆和瓷砖填缝剂而言依然是一个令人头痛的问题．泛碱通常不会造成砂浆明显的破坏．而主要是影响产品的感官质量．泛碱经常在建筑物投入使用后的很短时间内产生．此时正是工人．建筑师和业主对新建筑物外观质量最关心的时候．特别是当彩色砂浆的颜色较深时．表面形成的白斑会引起对比度强烈的不规则斑痕．     

Social motives and cognitive power–sex associations: Predictors of aggressive sexual behavior.

The present study investigated whether implicit social motives and cognitive power–sex associations would predict self-reports of aggressive sexual behavior. Participants wrote stories in response to Thematic Apperception Test pictures, which were scored for power and affiliation–intimacy motives. They also completed a lexical-decision priming task that provided an index of the strength of the cognitive association between the concepts of "power" and "sexuality." For men, high levels of power motivation and strong power–sex associations predicted more frequent aggression. There was also an interaction: Power motivation was unrelated to aggression for men with the weakest power–sex associations. For women, high levels of affiliation–intimacy motivation were associated with more frequent aggression. Strong power–sex associations were also predictive for women but only when affiliation–intimacy motivation was high. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Polymer dispersions and their interaction with mortar constituents and ceramic tile surfaces studied by zeta-potential measurements and atomic force microscopy

The interaction between mineral surfaces and organic polymer dispersions with different monomer base and protective colloids as present in tile adhesive mortar systems was investigated by measuring the ζ-potential and by direct observation by atomic force microscopy (AFM). The charge situation of pure mineral powders and pure polymer dispersions as well as their interaction in presence of different cementitious aqueous solutions was studied. The binding of Ca⁺⁺ ions leads to positive ζ-potentials for quartz or ceramic in calcium containing aqueous solutions and acts as a transmitter of attractive forces. However, the adsorption of sulfate ions may disturb such attraction.The interaction between polymer dispersions and ceramic (polished and original tile) or mica surfaces influenced by the presence of artificial cementitious pore solutions was observed by AFM. A flat index (height/diameter of latex particles in contact with these surfaces) was defined to quantify the polymer–mineral interface affinity. The different flat indices for different polymer–substrate combinations are mainly related to two parameters, the glass transition temperature of the copolymer and the stabilization system (steric versus cationic). Furthermore tapping phase imaging revealed significant heterogeneities in the inner structure of the polymer particles and inhomogeneous distribution at their surface probably related to local variations of the protective colloid, especially polyvinyl alcohol.     

Synthesis, solution structure and immune recognition of an epidermal growth factor-like domain from Plasmodium falciparum merozoite surface protein-1

The Plasmodium falciparum merozoite surface protein-1 19 kDa fragment (MSP-1(19)) comprises two closely packed EGF-like domains (EGF=epidermal growth factor), each stabilized by three disulfide bonds. The native conformation of this protein is important for eliciting P. falciparum growth inhibitory antibodies. Here we show that the N-terminal EGF domain alone can be chemically synthesized and efficiently refolded to a native-like state, as shown by its solution structure as determined by NMR spectroscopy. In order to study its immunogenicity, the domain was coupled through its N terminus to a phospholipid and incorporated into reconstituted influenza virus-like particles (virosomes). When used to immunize mice, the peptide-loaded virosomes elicited potent humoral immune responses that were shown by Western blots and immunofluorescence assays to cross-react with native MSP-1 on the surfaces of P. falciparum blood stage parasites. This opens the way for a medicinal chemistry-oriented approach to the study and optimization of the antigenicity of the protein as a potential malaria vaccine candidate, whilst exploiting the immunopotentiating properties of influenza virosomes as a delivery vehicle.     

Quantitative microstructure analysis of polymer-modified mortars

Digital light, fluorescence and electron microscopy in combination with wavelength‐dispersive spectroscopy were used to visualize individual polymers, air voids, cement phases and filler minerals in a polymer‐modified cementitious tile adhesive. In order to investigate the evolution and processes involved in formation of the mortar microstructure, quantifications of the phase distribution in the mortar were performed including phase‐specific imaging and digital image analysis. The required sample preparation techniques and imaging related topics are discussed. As a form of case study, the different techniques were applied to obtain a quantitative characterization of a specific mortar mixture. The results indicate that the mortar fractionates during different stages ranging from the early fresh mortar until the final hardened mortar stage. This induces process‐dependent enrichments of the phases at specific locations in the mortar. The approach presented provides important information for a comprehensive understanding of the functionality of polymer‐modified mortars.     

Aging and the psychological refractory period: Task-coordination strategies in young and old adults.

The apparently deleterious effect of aging on dual-task performance is well established, but there is little agreement about the source of this effect. Studies of the psychological refractory period (PRP) indicate that young adults can flexibly control dual-task performance through task-coordination strategies. Thus, the performance of older adults might differ from young adults because older adults use different task-coordination strategies. To test this hypothesis, the executive-process interactive control (EPIC) architecture was applied to quantify the reaction time data from two PRP experiments conducted with young (age 18–26) and older (age 60–70) adults. The results show that participants' ability to coordinate the processing of two tasks did not decline with age. However, dual-task time costs were greater in the older adults. Three sources for this increase were found: generalized slowing, process-specific slowing, and the use of more cautious task-coordination strategies by the older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)