A simple model of hyperbranched polymerisation involving AB<Subscript>2</Subscript> and B<Subscript><Emphasis Type="Italic">f</Emphasis></Subscript> core monomers and methods of narrowing the molecular size distribution

Summary A simple kinetic model of modelling hyperbranched polymerisation involving AB₂ and B_f core monomers is developed and analytical solutions of the model are presented. The number- and weight- average polymerisation degrees can be calculated using the model as functions of polymerisation time or conversion degree. Application of the model is tested for predicting the broadness of molecular size distribution of the hyperbranched polymers obtained by varying the procedures of feeding AB₂ monomer to polymerisation reactor.     

A two-dimensional model of the pressing section of a paper machine including dynamic capillary effects

Paper production is a problem with significant importance for society; it is also a challenging topic for scientific investigation. This study is concerned with the simulation of the pressing section of a paper machine. A two-dimensional model is developed to account for the water flow within the pressing zone. A Richards-type equation is used to describe the flow in the unsaturated zone. The dynamic capillary pressure–saturation relation is adopted for the paper production process. The mathematical model accounts for the coexistence of saturated and unsaturated zones in a multilayer computational domain. The discretization is performed by the MPFA-O method. Numerical experiments are carried out for parameters that are typical of the production process. The static and dynamic capillary pressure–saturation relations are tested to evaluate the influence of the dynamic capillary effect.     

Computer-assisted questionnaires may facilitate collection of quality-of-life (QOL) data: At a cost

Quality-of-life (QOL) measurement is becoming increasingly important in oncology clinics. QOL questionnaires were mostly designed for use in clinical trials, and therefore focus on group measurement, inevitably omitting some details or domains that may be relevant to the individual patient. Computers can assist in the delivery of QOL questionnaires by presenting questions and by modifying subsequent questions. This study attempted to evaluate the use of computer-assisted (CA-) questionnaires for collection of QOL data from oncology patients. A total of 88 patients completed a standard questionnaire, the EORTC QLQ-C30, and a computer-assisted version of the standard questionnaire on the same day. Both questionnaires were presented on a portable touchscreen computer. The CA-questionnaire allowed patients to pre-select domains from the standard questionnaire, and omit those which patients felt were irrelevant. Responses from both questionnaires were recorded, as well as exact and global agreement and time taken to complete the questionnaires. Although the time taken on CA-questionnaire was almost half that on the standard questionnaire, the levels of overall and exact agreement were relatively low. In general, patients reported lower levels of functioning and higher levels of symptoms on the standard questionnaire than CA-questionnaire. Computer-assisted questionnaires may provide a brief snapshot of patients’ QOL, however, some accuracy may be lost.     

Synthesis,structure and photocatalytic properties of nanoparticles from a carbon-containing composite based on silicon oxide modified with titanium dioxide

A pulsed plasmochemical method was used to obtain carbon-containing nanocomposites based on silicon oxide modified with titanium dioxide. The material contained a Si_xC_yO_z carrier with an average size of 50–150?nm and a shell of fine particles with an average size of 5–10?nm. The phase composition and morphology of the synthesized composites was studied by X-ray diffraction and transmission electron microscopy. The optical and photocatalytic properties of the nanoparticles from the carbon-based composite based on silicon oxide encapsulated in titanium dioxide were studied. The synthesized composite showed a high photocatalytic activity due to the decomposition of methylene blue under the influence of visible light in the wavelength range of 460–630?nm.     

Assessing Acute Toxicity of Selected Packages Internal Layers Extracts using Microtox®

In the scientific literature related to the widely understood issue of packaging materials designed to have contact with food (food contact materials), there is much information on raw materials used for their production, as well as their physiochemical properties, types and parameters. Unfortunately, not much attention is given to the issues concerning migration of toxic substances from packaging and its actual influence on the health of the final consumer, even though health protection and food safety are the priority tasks. The goal of this study was to estimate the impact of particular foodstuff packaging type, food production and storage conditions on the degree of leaching of potentially toxic compounds to foodstuffs with the use of the acute toxicity test Microtox^®. From all simulants studied, the 3% acetic acid in water proved to cause significant migration of toxic compounds with increase of time and temperature of extraction and justified the hypothesis that food products with low pH values (stored in cans) cause significant damage to cans internal resin filing and is a reason of increased migration rate of package material to foodstuff. Copyright © 2017 John Wiley & Sons, Ltd.     

Russian scatterometer: discussion of the concept and the numerical simulation of wind field retrieval

Orbital scatterometry is briefly overviewed and its trends are indicated. Two scatterometer concepts are currently considered for trade-offs: with fixed and rotating antenna systems. The concept with a rotating antenna system was selected and SeaWinds was chosen as the prototype for the first Russian scatterometer. The scatterometer concept was then further developed and instead of two pencil beams, a fan-beam antenna was proposed (about 1° × 6°). The fan-beam antenna allows successive measurements for horizontal and vertical polarization in each wind vector cell (WVC). This increases the number of observations of the WVC at different incidence and azimuth angles during flight. The scatterometer parameters required to implement the proposed measurement geometry for an orbit altitude of 650 km and a swath width of 1525 km are discussed. A numerical scatterometer model that accounts for both the specifications and the observation geometry is developed. The scatterometer performance, with subsequent formation of a swath and splitting into WVCs, is simulated. The procedure of wind vector retrieval includes two stages: 1) determining wind speed and wind direction in a single WVC; and 2) using the information from adjacent WVCs to correct wind direction. It is shown that the accuracy of wind direction retrieval by a WVC can be increased by simultaneous radar cross-section (RCS) measurements at vertical and horizontal polarization. The basic error in determining wind direction is due to a 180° wind direction ambiguity caused by the form of RCS azimuth dependence. Two-dimensional median filtering is commonly employed in scatterometry to increase the accuracy of wind direction retrieval. In this study, two-dimensional angular median filtering was employed and it is shown that the error in wind direction retrieval significantly decreased. The results of the research indicate that wind field can be retrieved by the new scatterometer with the level of precision required.     

Increasing the performance of asymmetric pervaporation membranes for the separation of methanol/methyl-tert-butyl ether mixtures by the introduction of sulfonated polyimide into the poly(amide-imide) matrix

A series of novel asymmetric membranes from polymer composites of poly(amide-imide) with various content of sulfonated polyimide (1–6 wt%) was obtained through the nonsolvent-induced phase separation process. Selective transport properties of the obtained materials were investigated in terms of pervaporation separation of methanol/methyl-tert-butyl ether mixtures at different temperatures. The introduction of the sulfonated polyimide to the poly(amide-imide) matrix leads to a significant increase in membrane flux and an overall decrease in the process selectivity. Composite membranes having 1 wt% sulfonated polyimide in the matrix showed increased values of membrane flux (0.960 kg m⁻² h⁻¹ in comparison with 0.682 kg m⁻² h⁻¹ for unmodified membranes at 40°C, 10 wt% methanol), while having similar selectivity values (79.2 wt% methanol in permeate in comparison with 82 wt% for unmodified membranes at 40°C, 10 wt% methanol). Modified membrane showed the highest separation factor of 147 while separating methanol from its 3 wt% mixture with methyl-tert butyl ether at 52°C with the overall flux of 1.01 kg m⁻² h⁻¹. A semiempirical mathematical model was developed and applied to test the efficiency of obtained membranes in the hybrid process of methanol/methyl-tert-butyl ether mixtures separation.     

Myocardial Hypertrophy and Fibrosis Are Associated with Cardiomyocyte Beta-Catenin and TRPC6/Calcineurin/NFAT Signaling in Spontaneously Hypertensive Rats with 5/6 Nephrectomy

Background: Arterial hypertension (AH) is associated with heart and chronic kidney disease (CKD). However, the precise mechanisms of myocardial remodeling (MR) in the settings of CKD remain elusive. We hypothesized that TRPC6, calcineurin/NFAT, and Wnt/β-catenin signaling pathways are involved in the development of MR in the background of CKD and AH. Methods: Early CKD was induced by performing a 5/6 nephrectomy (5/6NE) in spontaneously hypertensive rats (SHR-NE). Sham-operated (SO) SHR (SHR-SO) and Wistar Kyoto (WKY-SO) rats served as controls. Systolic blood pressure (SBP), heart rate, myocardial mass index (MMI), serum creatinine, cardiomyocyte diameter (dCM), myocardial fibrosis (MF), serum and kidney α-Klotho levels, myocardial expression of calcineurin (CaN), TRPC6, and β-catenin were measured two months after 5/6NE or SO. Results: NE-induced kidney dysfunction corresponded to mild-to-moderate human CKD and was associated with an increase in FGF23 and a decrease in renal α-Klotho. The levels of SBP, MMI, dCM, and MF were higher in SHRs compared to WKY-SO as well as in SHR-NE vs. SHR-SO. The MR was associated with increased cardiomyocyte expression of CaN/NFAT and β-catenin along with its intracellular re-distribution. TRPC6 protein levels were substantially elevated in both SHR groups with higher Trpc6 mRNA expression in SHR-NE. Conclusions: The Wnt/β-catenin and TRPC6/CaN/NFAT hypertrophic signaling pathways seem to be involved in myocardial remodeling in the settings of AH and CKD and might be mediated by FGF23 and α-Klotho axis.     

Formation of Polycrystalline Boron Carbide B4C with Elevated Fracture Toughness

We have studied the processes of formation of high-density polycrystalline boron carbide B₄C during sintering under high pressure (5.5 GPa) and at high temperature (2200 K). Study of the structure by transmission electron microscopy showed that under the indicated conditions for sintering B₄C powders with original particle size range 2–80 µm, processes of primary recrystallization occur, as a result of which interlayers of nanodispersed grains (10–50 nm) are formed in the near-surface regions of the original coarse grains. The microhardness of such material is 41 GPa, and the fracture toughness is 7.2 MPa · m^1/2.__________Translated from Poroshkovaya Metallurgiya, Nos. 1–2(441), pp. 90–101, January–February, 2005.     

Physical aging of poly(diethylene glycol‐p,p′bibenzoate)

The structure of a quenched sample of a liquid crystalline polyester, poly(diethylene glycol‐p,p′‐bibenzoate) (PDEB), and its physical aging was studied by microhardness methods (MH), wide‐angle X‐ray scattering (WAXS), and positron annihilation lifetime spectroscopy (PALS). It was established that the smectic layers in the liquid crystalline domain are oriented parallel to the sample plane. Physical aging leads to an increase of either the Vickers microhardness, directly related to the elastic modulus of the material, or the total microhardness, which includes all the components of the overall deformation. These mechanical changes are due to a decrease in the sizes of nanopores and the consequential increase of the density of the disordered phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2363–2368, 2002