[en] Poly-(methyl methacrylate-co-benzyl methacrylate) polarization-maintaining optical fibers are known for their high response to normal stress. In this report, responses to higher stress levels up to 0.45 MPa were investigated. The stress amplitude and direction in the fiber cross section were calculated and analyzed with a coincident mode-field obtained from the near-field pattern. The stress amplitude varies significantly in the horizontal direction and is considered to create multiple phases, explaining the measurement results. To investigate possible permanent deformation, the core yield point profile was analyzed. Although it largely exceeds the average applied stress, the calculated stress distribution indicates that the core could partially experience stress that exceeds the yield point

[en] Short note

[en] The miscibility of poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks (IPNs) has been studied by probing the conformational mobility of the component polymer chains. These IPNs exhibit the phenomenon of forced compatibilization. In a conventional heating differential scanning calorimetry (DSC) thermogram, the highly cross-linked IPN shows a single glass transition which covers a temperature interval of around 100^deg C; in contrast, loosely cross-linked IPNs show two glass transitions. The conformational mobility in these IPNs is studied by subjecting them to isothermal annealings at temperatures in the region of the glass transition and below it. The DSC scans measured after these treatments allow one to determine the temperature interval in which the sample is out of thermodynamic equilibrium but keeps enough conformational mobility to relax during the isothermal annealing in such a way that the enthalpy loss is measurable with the sensitivity of a conventional DSC. The results allow one to reach some conclusions about the compositional distribution of the IPN on the nanometre scale

[en] The effects of D-amino acids at Asp²³ and Ser²⁶ residues on the conformational preference of β-amyloid (Aβ) peptide fragment (Aβ_20-29) have been studied using different spectroscopic techniques, namely vibrational circular dichroism (VCD), vibrational absorption, and electronic circular dichroism. To study the structure of the Aβ_20-29, [D-Asp²³]Aβ_20-29, and [D-Ser²⁶]Aβ_20-29 peptides under different conditions, the spectra were measured in 10 mM acetate buffer (pH 3) and in 2,2,2-trifluoroethanol (TFE). The spectroscopic results indicated that at pH 3, Aβ_20-29 peptide takes random coil with β-turn structure, while [D-Ser²⁶]Aβ_20-29 peptide adopts significant amount of polyproline II (PPII) type structure along with β-turn contribution and D-Asp-substituted peptide ([D-Asp²³]Aβ_20-29) adopts predominantly PPII type structure. The increased propensity for PPII conformation upon D-amino acid substitution, in acidic medium, has important biological implications. In TFE, Aβ_20-29, [D-Asp²³]Aβ_20-29, and [D-Ser²⁶]Aβ_20-29 peptides adopt 3₁₀-helix, α-helix, and random coil with some β-turn structures, respectively. The VCD data obtained for the Aβ peptide films suggested that the secondary structures for the peptide films are not the same as those for corresponding solution and are also different among the Aβ peptides studied here. This observation suggests that dehydration can have a significant influence on the structural preferences of these peptides

[en] The data of the fourth column of table 3 (S(X) IAM), reported on pages 2556 and 2557, were erroneously scaled by a factor √M, with M the molecular mass of the compound. Therefore, the data of S(X) IAM for PMMA on page 2556 and the data of S(X) IAM for fat on page 2557 must be multiplied by a factor of 10.01 and 29.21 respectively. Moreover, due to a mistake in Thompson expression evaluations, the data of Bradley et al (1989) reported in figure 1 had results enhanced beyond x=2.5 mm^-1. After the proper computation, these discrepancies were removed. The results of molecular differential cross section and form factor for coherent scattering presented in the original version remain correct. The authors' thanks are due to Dr Robert Leclair - from Carleton, Canada - and to Dr David Dance - from London, UK - for pointing out these errors which were due to the same computer program mistake in forming the final tabulations and graphic files. (author)

[en] Freezing temperature lowerings of aqueous solutions of tartaric acid, sodium hydrogen tartrate, sodium dihydrogen citrate, potassium dihydrogen citrate, disodium hydrogen citrate, sodium citrate and potassium citrate were determined. These values and those taken from the literature for potassium tartrate were used in the determination of the osmotic and activity coefficients in the studied systems, via the numerical integration of the Gibbs-Duhem equation

[en] Short communication. 4 refs

[en] This work involve deals with experimental part, deals with methods and the ways used in the synthesis of 3- aryl phthalides startingfrom phthalal aldehydic acid and many phenoles and anisols containing electron with drawing groups such as (CO2H, COR, CHO, NO2), and some of the reactions that started with compounds prepared previously. (15 tabs., 12 figs., 47 refs.)

[en] Noroviruses are the main cause of viral gastroenteritis with new variants emerging frequently. There are three norovirus genogroups infecting humans. These genogroups are divided based on the sequence of their major capsid protein, which is able to form virus-like particles (VLPs) when expressed recombinantly. VLPs of the prototypical GI.1 Norwalk virus are known to disassemble into specific capsid protein oligomers upon alkaline treatment. Here, native mass spectrometry and electron microscopy on variants of GI.1 and of GII.17 were performed, revealing differences in terms of stability between these groups. Beyond that, these experiments indicate differences even between variants within a genotype. The capsid stability was monitored in different ammonium acetate solutions varying both in ionic strength and pH. The investigated GI.1 West Chester isolate showed comparable disassembly profiles to the previously studied GI.1 Norwalk virus isolate. However, differences were observed with the West Chester being more sensitive to alkaline pH. In stark contrast to that, capsids of the variant belonging to the currently prevalent genogroup GII were stable in all tested conditions. Both variants formed smaller capsid particles already at neutral pH. Certain amino acid substitutions in the S domain of West Chester relative to the Norwalk virus potentially result in the formation of these T  =  1 capsids. (paper)

[en] Highlights: • TOTM and DEHT were the dominant alternative plasticizers in the sedimentary environment. • Proximity to industrial complexes was crucial for sedimentary distribution of plasticizers. • Clear increasing trends in phthalates and alternative plasticizers were observed over time. • Industrialization and population were major factors affecting plasticizer contamination. • Sedimentary DEHP levels may pose adverse health effects for benthic organisms. Domestic and global regulations on phthalates have led to the introduction of non-phthalate plasticizers (NPPs) in industrial markets as alternative plasticizers. In this study, phthalates and NPPs from surface and core sediment samples taken from industrialized bays in Korea were measured to determine their distribution, contamination sources, historical records, and the ecological risks they posed. Phthalates and alternative plasticizers were detected in all surface samples and sediment cores, indicating ubiquitous contamination. Predominant phthalates were di(2-ethylhexyl)phthalate (DEHP), diisononyl phthalate (DiNP), and diisodecyl phthalate (DiDP) and di(2-ethylhexyl)terephthalate (DEHT) and tris(2-ethylhexyl)trimellitate (TOTM) were the most common NPPs. The total concentrations of phthalates and NPPs ranged from 76.3 to 59,400 ng/g dry weight and 95%) exceeded quality guidelines for DEHP, implying a potential risk for benthic organisms. This is the first report on historical trends of phthalates and alternative plasticizers.