Synthetic resins: I. Preparation and characterization of resins from substituted benzoic acid–formaldehyde

A number of resins have been prepared by the condensation of substituted benzoic acid with formaldehyde in the presence of different acids and bases as the catalyst. The intrinsic viscosity and Huggin's and Kraemer's constants of the resins were determined. The solubility behavior of the resins was studied. The IR spectra and the thermogravimetric analysis of the resins were also studied. The values of the energy of activation of degradation of the resins were computed by using the Freeman–Anderson method.     

Photo-induced graft copolymerization: XVI: Graft copolymerization of methyl methacrylate onto nylon-6 using isoquinoline-sulfur dioxide and α-picoline-sulphur dioxide charge-transfer complexes as photoinitiators

The photo-induced graft copolymerization of methyl methacrylate onto nylon-6 fiber was investigated using isoquinoline-sulfur dioxide and α-picoline-sulfur dioxide charge-transfer complexes as the photoinitiators. The graft copolymerization was carried out within the temperature range of 35–50°C and from the corresponding Arrhenius plot, the energy of activation has been evaluated. The effect of monomer, initiators, inhibitors, etc. on the graft yield has been investigated. The effect of solvent on the rate of grafting has also been investigated from which the chain-transfer constant (C_s) of the solvent has been evaluated. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. The suitable mechanism has been suggested and the kinetic rate expression has been derived.     

Texture Properties of Dutch-Type Cheese as a Function of Its Location and Ripening

The aim of the study was to explore texture changes of Dutch-type cheese at its different locations during 126-day ripening at the temperature common for maturation of this type of cheese (10°C). Each block of cheese was divided into 3 slices and texture properties were studied in 13 segments evenly distributed in each slice. Due to cheese brining, a significant increase of hardness and elastic component was reported especially in the edge segments. During the subsequent ripening, both hardness and elastic component of natural cheese decreased gradually in all segments and slices. Studied parameters of individual parts of cheese did not demonstrate uniform rate of changes during the ripening period. In the whole experiment (even after 126-day ripening), hardness and elastic component of the cheese in core showed lower values compared to those obtained in the edge of all slices.     

A Fast HPLC Method for Determination of Vitamin E Acetate in Dietary Supplements Using Monolithic Column

A simple and fast high-performance liquid chromatography (HPLC) method with rapid separation on monolithic column has been developed for quantitative determination of vitamin E acetate in dietary supplements. Commercial samples of dietary supplements were extracted with 100 % methanol with the help of ultrasound bath. A 20-μL sample volume of the filtered solution was directly injected into the HPLC system. Separation of ballast matrix, vitamin E acetate, and internal standard cholecalciferol was performed on the monolithic column Chromolith Performance RP-18e column (100?×?4.6 mm) with mobile phase methanol/water (98:2, v/v) at a flow rate of 2.0 mL min^?1 and at temperature 30 °C. The detector was set at 290 nm. Under the optimum chromatographic conditions, standard calibration curve was measured with good linearity—correlation coefficient for vitamin E acetate (r?=?0.9992; n?=?6) between the peak areas and concentrations of vitamin E acetate. Accuracy of the method defined as a mean recovery was in the range 96.4–103.6 % for all dietary supplements. The intraday method precision was satisfactory and relative standard deviation of sample analysis including preparation and determination of different dietary supplements was in the range 1.1–3.6 %. The developed method has shown high sample throughput during sample preparation process and short time (3.5 min) of analysis.     

Dry pressed ceramic tiles based on fly ash–clay body: Influence of fly ash granulometry and pentasodium triphosphate addition

Fly ash from brown coal (70 wt.%) and stoneware clay (30 wt.%) were used for the dry pressed ceramic tiles (according to EN 14411) raw materials mixture. The effects of fly ash milling and pentasodium triphosphate addition as a deflocculant and fluxing agent on the properties of green body (flexural strength, bulk density) and fired body (EN ISO 10545—water absorption, bulk density, true density, apparent porosity, flexural strength, frost resistance) were studied and explained as a function of the firing temperature (1000–1150 °C). Fly ash milling (corresponding to 5 wt.% residue of fly ash grains on 0.063 mm sieve) increased the sintering abilities of the fly ash–clay body. A similar effect was achieved by 1.3 wt.% pentasodium triphosphate (PST) addition with an increase in green body flexural strength and a decrease in water content of the granulate. Fly ash–clay bodies can be frost resistant with water absorption above 10% due to positive pore size distribution, which were examined using the high-pressure mercury porosimetry method.     

Micromachined nanocalorimetric sensor for ultra-low-volume cell-based assays

Current strategies for cell-based screening generally focus on the development of highly specific assays, which require an understanding of the nature of the signaling molecules and cellular pathways involved. In contrast, changes in temperature of cells provides a measure of altered cellular metabolism that is not stimulus specific and hence could have widespread applications in cell-based screening of receptor agonists and antagonists, as well as in the assessment of toxicity of new lead compounds. Consequently, we have developed a micromachined nanocalorimetric biological sensor using a small number of isolated living cells integrated within a subnanoliter format, which is capable of detecting 13 nW of generated power from the cells, upon exposure to a chemical or pharmaceutical stimulus. The sensor comprises a 10-junction gold and nickel thermopile, integrated on a silicon chip which was back-etched to span a 800-nm-thick membrane of silicon nitride. The thin-film membrane, which supported the sensing junctions of the thermoelectric transducer, gave the system a temperature resolution of 0.125 mK, a low heat capacity of 1.2 nJ mK(-1), and a rapid (unfiltered) response time of 12 ms. The application of the system in ultra-low-volume cell-based assays could provide a rapid endogenous screen. It offers important additional advantages over existing methods in that it is generic in nature, it does not require the use of recombinant cell lines or of detailed assay development, and finally, it can enable the use of primary cell lines or tissue biopsies.     

Allium micronucleus (MNC) assay to assess bioavailability, bioconcentration and genotoxicity of mercury from solid waste deposits of a chloralkali plant, and antagonism of L-cysteine

Samples of solid waste from a chloralkali plant were bioassayed employing the Allium micronucleus (MNC) assay. The endpoints measured were root length, root mercury and frequency of root meristematic cells with MNC. Chemical extraction methods such as 10% HNO3, ammonium acetate-EDTA and 0.05 or 0.1 M CaCl2 were used to assess the bioavailability of mercury from soil contaminated with solid waste. Analysis of mercury was by cold vapour atomic absorption spectrophotometry. The frequency of MNC induced by contaminated soil, which followed a concentration-response curve, was statistically correlated with soil mercury, extractable mercury and root mercury. The antagonism of L-cysteine against the suppression of root growth and induction of MNC by solid waste suggested the involvement of mercury as well as thiol groups in the process. The threshold assessment values, such as the median effective concentration (EC50) for root growth, gross toxicity concentration tested (GTCT) as indicated by complete inhibition of sprouting of roots, lowest effective concentration tested (LECT) and highest ineffective concentration tested (HICT) for induction of MNC, were determined. These assessment values may be useful for environmental management and regulatory purposes. Furthermore, the detection limit of the Allium MNC assay for solid waste mercury as indicated by LECT was 9.6 mg kg-1 which corresponded to 0.13 mg kg-1 of 0.05 M CaCl2 extractable or 8.3 mg kg-1 dry weight bioconcentrated mercury.