Elastic scattering and light transport in three-dimensional collagen gel constructs: a mathematical model and computer simulation approach

A mathematical modeling approach for elastic scattering and light propagation is presented, which can be used to obtain the scattering coefficient, the index of refraction, and the distribution of the collagen fibrils in a gel. Collagen fibrils can be realistically represented by small cylindrical particles. The analysis of the scattering of light by such particles provides the scattering coefficient. Light transport in multilayered tissues has been modeled and the collagen fibrils scattering coefficient has been considered as main input parameters. Assuming that a gel is composed of fibrils with the same diameter, it is possible to obtain all the input parameters of the model and, therefore, a simulated spectrum. This can be repeated for several diameters. Considering a gel composed of fibrils with different diameters, it is possible to obtain a best-fitting simulated spectrum as a weighted sum (least-square-error based) of the spectra corresponding to several fibril diameters, and, therefore, obtain an estimate of the percentages of fibrils of each diameter in the gel. Moreover, the scattering coefficient and refractive index, which are also provided by the model, are relevant parameters as they relate to tissue properties in their own right.     

Changes of liquid-crystalline polymer structure with temperature

Summary Thermal changes in the structural state of liquid crystalline polymers with mesogenic side groups and the kinetics of mesophase formation were studied by means of smallangle X-ray scattering.Part 3: V.Tsulcruk,O.Lokhonya,V.Shilov,V.Kuzmina,Yu.Lipatov Makromol.Chem,,Rapid Commun.4,595(1983)     

Antecedents and consequences of trust in a social media brand: A cross-cultural study of Twitter

This study extends brand relationship theory to the context of the microblogging platform Twitter. The authors investigate the impact of Twitter trust on users’ intentions to continue using the platform and to “follow” brands that are hosted on Twitter (the trust transfer phenomenon). They also explore the role of perceived self-Twitter personality match in strengthening trust towards the Twitter brand. A cross-cultural American–Ukrainian sample allows to identify potential culture-based differences in brand personality and brand trust concepts. The results show that the positive effect of trust in Twitter on its users’ patronage intentions is robust across two cultures with diverse history and ideology. An important novel finding is the influence of trust in Twitter on patronage intentions towards the businesses hosted on Twitter. However, this relationship reaches statistical significance only in the Ukrainian sample, signaling potential differences in the trust transfer processes in different cultures. The study confirms the role of similarity in personality traits between Twitter users and the Twitter brand in engendering trust in Twitter. The salience of different personality traits in the “personality match – Twitter trust” link for different cultures suggests important implications for global marketers.     

Investigation into the influence of organic modifiers and ultradispersed hybrid fillers on the structure and properties of glass-ceramic coatings prepared by the sol-gel method

Glass-ceramic coatings on nickel and its alloys are produced from organic-inorganic hybrids by the sol-gel method. The coatings are applied using sol-gel systems composed of tetraethoxysilane (inorganic dopant), as well as of finely dispersed oxide and ultradispersed hybrid fillers. Acrylic and methacrylic acid derivatives are taken as organic modifiers. Oligocarbonate dimethacrylate-substituted tetranuclear titanium oxide clusters are used as the ultradispersed hybrid filler. The influence of the organic modifiers and ultradispersed hybrid fillers on the physicochemical processes occurring in the sol-gel systems and on the electrical parameters of the coatings are experimentally studied, and the data obtained are analyzed.     

The Influence of Low- and High-Molecular Hydroxyl-Containing Additives on the Stability of Sol–Gel Tetraethoxysilane-Based Systems and on the Structure of Hybrid Organic–Inorganic Coatings

Organic–inorganic composites are synthesized by introducing a number of low- and high-molecular water-soluble polyhydroxyl compounds (with different molecular weights and different molecular structures) into sols based on tetraethoxysilane. The coatings on nickel substrates are prepared by adding chromium dioxide as a finely disperse filler to the soles. The rheological properties of the sol–gel systems synthesized are investigated, and the surface condition and the microstructure of the coatings formed are examined. The xerogels and the coatings are studied by differential thermal and X-ray powder diffraction analyses.     

Microstructural parameters of dispersion strengthened Cu–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> materials

The aim of the article was to evaluate the microstructural parameters of Cu–Al₂O₃ dispersion strengthened materials with different volume fraction of Al₂O₃ phase. For analyses of dispersoids Al₂O₃, the extraction carbon replica was used. The distribution of Al₂O₃ particles in the matrix was estimated by three methods (quadrant count method, polygonal method, and by interparticle distances), these methods showed that particle distribution in material with 1 vol.% of Al₂O₃ is very close to the Poisson point process (PPP), which is a model of randomly distributed points. Particle distributions in materials with 8 and 10 vol.% of Al₂O₃ achieve features of regularity proved mainly by the spherical contact distance.     

Metformin Attenuates Postinfarction Myocardial Fibrosis and Inflammation in Mice

Diabetes is a major risk factor for the development of cardiovascular disease with a higher incidence of myocardial infarction. This study explores the role of metformin, a first-line antihyperglycemic agent, in postinfarction fibrotic and inflammatory remodeling in mice. Three-month-old C57BI/6J mice were submitted to 30 min cardiac ischemia followed by reperfusion for 14 days. Intraperitoneal treatment with metformin (5 mg/kg) was initiated 15 min after the onset of reperfusion and maintained for 14 days. Real-time PCR was used to determine the levels of COL3A1, αSMA, CD68, TNF-α and IL-6. Increased collagen deposition and infiltration of macrophages in heart tissues are associated with upregulation of the inflammation-associated genes in mice after 14 days of reperfusion. Metformin treatment markedly reduced postinfarction fibrotic remodeling and CD68-positive cell population in mice. Moreover, metformin resulted in reduced expression of COL3A1, αSMA and CD68 after 14 days of reperfusion. Taken together, these results open new perspectives for the use of metformin as a drug that counteracts adverse myocardial fibroticand inflammatory remodeling after MI.     

The mRubyFT Protein,Genetically Encoded Blue-to-Red Fluorescent Timer

Genetically encoded monomeric blue-to-red fluorescent timers (mFTs) change their fluorescent color over time. mCherry-derived mFTs were used for the tracking of the protein age, visualization of the protein trafficking, and labeling of engram cells. However, the brightness of the blue and red forms of mFTs are 2–3- and 5–7-fold dimmer compared to the brightness of the enhanced green fluorescent protein (EGFP). To address this limitation, we developed a blue-to-red fluorescent timer, named mRubyFT, derived from the bright mRuby2 red fluorescent protein. The blue form of mRubyFT reached its maximum at 5.7 h and completely transformed into the red form that had a maturation half-time of 15 h. Blue and red forms of purified mRubyFT were 4.1-fold brighter and 1.3-fold dimmer than the respective forms of the mCherry-derived Fast-FT timer in vitro. When expressed in mammalian cells, both forms of mRubyFT were 1.3-fold brighter than the respective forms of Fast-FT. The violet light-induced blue-to-red photoconversion was 4.2-fold less efficient in the case of mRubyFT timer compared to the same photoconversion of the Fast-FT timer. The timer behavior of mRubyFT was confirmed in mammalian cells. The monomeric properties of mRubyFT allowed the labeling and confocal imaging of cytoskeleton proteins in live mammalian cells. The X-ray structure of the red form of mRubyFT at 1.5 Å resolution was obtained and analyzed. The role of the residues from the chromophore surrounding was studied using site-directed mutagenesis.