Experimental Evaluation of Food-Grade Semi-Refined Carrageenan Toxicity

The safety of food additives E407 and E407a has raised concerns in the scientific community. Thus, this study aims to assess the local and systemic toxic effects of the common food additive E407a in rats orally exposed to it for two weeks. Complex evaluations of the effects of semi-refined carrageenan (E407a) on rats upon oral exposure were performed. Local effects of E407a on the intestine were analyzed using routine histological stains and CD68 immunostaining. Furthermore, circulating levels of inflammatory markers were assessed. A fluorescent probe O1O (2- (2′-OH-phenyl)-5-phenyl-1,3-oxazole) was used for evaluating the state of leukocyte cell membranes. Cell death modes of leukocytes were analyzed by flow cytometry using Annexin V and 7-aminoactinomycin D staining. Oral administration of the common food additive E407a was found to be associated with altered small and large intestinal morphology, infiltration of the lamina propria in the small intestine with macrophages (CD68⁺ cells), high systemic levels of inflammation markers, and changes in the lipid order of the phospholipid bilayer in the cell membranes of leukocytes, alongside the activation of their apoptosis. Our findings suggest that oral exposure to E407a through rats results in the development of intestinal inflammation.     

Scattering and reflective properties of ordered mesoporous silica films

Ordered mesoporous and nonporous silica films were studied by analysis of reflection spectra and hemispherical elastic light scattering (HELS). The real and imaginary parts of the index of the films were estimated from the reflection spectra. The HELS angular distribution of the mesoporous film shows a minimum, which has been interpreted as an interference pattern coming from the beams scattered by the mesopores.     

Evaluation of Aluminium Alloys Degradation in Aging Aircraft

The specimens of D16ATHB and B95T1 aluminum alloys (like 2024T3 and 7075T6 alloys, respectively) cut out from lower and upper wing skins of AN-12 aircraft after 40 years exploitation are investigated. The dependencies between mechanical characteristics and electrical conductivity obtained for long-term exploited alloys show a radically different trend in comparison with known for alloys in as-received state after various heat treatments. Such data are explained by results of materials fine structure study. Nondestructive eddy current (EC) method and instrument for aluminum alloys degradation monitoring in aging aircraft are analyzed.     

Laser‐Assisted Strain Engineering of Thin Elastomer Films to Form Variable Wavy Substrates for Cell Culture

Endothelial and epithelial cells usually grow on a curved environment, at the surface of organs, which many techniques have tried to reproduce. Here a simple method is proposed to control curvature of the substrate. Prestrained thin elastomer films are treated by infrared laser irradiation in order to rigidify the surface of the film. Wrinkled morphologies are produced upon stress relaxation for irradiation doses above a critical value. Wrinkle wavelength and depth are controlled by the prestrain, the laser power, and the speed at which the laser scans the film surface. Stretching of elastomer substrates with a “sand clock”‐width profile enables the generation of a stress gradient, which results in patterns of wrinkles with a depth gradient. Thus, different combinations of topography changes on the same substrate can be generated. The wavelength and the depth of the wrinkles, which have the characteristic values within a range of several tens of µm, can be dynamically regulated by the substrate reversible stretching. It is shown that these anisotropic features are efficient substrates to control polarization of cell shapes and orientation of their migration. With this approach a flexible tool is provided for a wide range of applications in cell biophysics studies.     

Synthesis and evaluation of N,N-dibutylundecenamide as new eco-friendly plasticizer for polyvinyl chloride

Journal of Materials Science - Tertiary fatty amide, namely N,N-dibutylundecenamide (DBUA), has been synthesized and evaluated as potential plasticizer for polyvinyl chloride (PVC). Homogeneous...     

Trypsinization-dependent cell labeling with fluorescent nanoparticles

Trypsin is often used to detach adhered cell subculture from a substrate. However, the proteolytic activity of trypsin may harm cells by cleaving the cell membrane proteins. The present study shows that cellular uptake of fluorescent nanoparticles is remarkably increased within 24 h after trypsinization. These results highlight the trypsin-induced protein digestion, provoking leaky cell plasma membrane which leads to the strongly enhanced cellular uptake of the nanoparticles. To prevent this effect, one should expose cells to the nanoparticle (NP)-based fluorescent labels at least 48 h after trypsinization.     

Microstructure Evolution and Pinning of Boundaries by Precipitates in a 9 pct Cr Heat Resistant Steel During Creep

Structural changes in a 9 pct Cr martensitic steel during a creep test at 923 K (720 °C) under the applied stress of 118 MPa were examined. The tempered martensite lath structure (TMLS) was characterized by M₂₃C₆-type carbide particles with an average size of about 110 nm and MX-type carbonitrides with a size of 40 nm. The M₂₃C₆ particles were located on the packet/block/lath boundaries, whereas the MX precipitates were distributed homogeneously throughout TMLS. TMLS in the grip portion of the crept specimen changed scarcely during the tests. In contrast, the structural changes in the gauge section of the samples were characterized by the evolution of relatively large subgrains with remarkably lowered density of interior dislocations within former martensite laths. The formation of a well-defined subgrain structure in the gauge section was accompanied by the coarsening of M₂₃C₆ carbides and precipitations of Laves phase during creep. The most pronounced structural changes occurred just at the beginning of the tertiary creep regime, which was interpreted as a result of the change in the mechanism of grain boundary pinning by precipitates.     

On the stress-free lattice expansion of porous cordierite

An extensive investigation of the lattice expansion (up to 1200 °C) of porous synthetic cordierite (obtained by firing a mixture of talc, clay, alumina and silica) was carried out using time-of-flight neutron diffraction at LANSCE, Los Alamos, NM, USA and FNLP, Dubna, Russia. An extruded rod and several powders, with different particle size (dispersity), were studied, with the aim of monitoring the variation of the (lattice) micro-strain as a function of temperature and its influence on the microscopic and macroscopic thermal expansion. Results show a different expansion of the a- and b-axes of the orthorhombic cell (in the rod above 800 °C). While the finest powder seems to contract more along the c-axis, thus hinting at the presence of smaller stress, the integral peak width increases as a function of temperature in the intermediate range (300–700 °C). This could be explained by the integrity factor modeling in terms of micro-cracking. In polycrystalline cordierite, the model implies tension along the a- and b-axes (positive thermal expansion) accompanied by compression along the c-axis (negative thermal expansion) and a stress release upon cooling, via a thermal micro-cracking mechanism. The calculations of the cordierite macroscopic thermal expansion having as input crystal axial expansions assumed to be stress-free allowed us to conclude that even a fine powder (5 μm particle size) cannot be considered completely stress-free. This conclusion is supported by microstructural observations.