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11.
The small angle X-ray scattering (SAXS) was used to examine structural changes of starches after γ-irradiation with 10, 20, 30 kGy doses. The diminution of intensity of small-angle reflexion relating to 100 A spacing indicates destruction of long-range ordering in granules after γ-irradiation. It was observed as well in the case of irradiation of dry pure starches as a starch contained in potatoes. The method suggests possibility of quick identification of irradiated foodstuffs. 相似文献
12.
Dorota Neugebauer Paulina Maksym‐Bębenek Anna Mielańczyk Tadeusz Biela 《Polymer Engineering and Science》2013,53(6):1146-1153
The reactive oxirane groups were incorporated into the macromolecule as substituents in the side chains of loosely‐grafted copolymer or in the arms of star‐shaped copolymer using glycidyl methacrylate (GMA) in the controlled atom transfer radical polymerization (ATRP). The branched GMA copolymers with various architectures were obtained by using hydrophobic copolymers containing six and seven units of caprolactone 2‐(methacryloyloxy)ethyl ester (CLMA) functionalized with bromoester groups, and trifunctional poly(ε‐caprolactone) (PCL), as well as hydrophilic tri‐, and six‐functional acetal derivatives of D ‐glucopyranosides as (macro)initiators with biodegradable and biocompatible properties. The well‐defined copolymers with core‐shell structures and polymerization degrees of GMA in the range of 20–100 per side chain/arm at 20–70% of monomer conversion within 1–6 h and narrow molecular weight distributions (Mw/Mn = 1.14–1.4) were obtained. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers 相似文献
13.
Corneliu Hamciuc Elena Hamciuc Tadeusz Pakula Lidia Okrasa 《Polymer-Plastics Technology and Engineering》2013,52(1):143-148
Aromatic silicon-containing poly(amide-imide)s have been prepared by low temperature solution polycondensation reaction of various aromatic diamines having ether bridges between phenylene rings with a diacid chloride, namely bis[N-(4-chlorocarbonylphenyl) phthalimidyl]dimethylsilane. These polymers were easily soluble in polar amidic solvents such as N-methylpyrrolidone,N,N-dimethylacetamide, and N,N-dimethylformamide and can be cast from solutions into thin, flexible films. They showed good thermal stability, with initial decomposition temperature being above 410°C and glass transition temperature in the range of 263–285°C. The polymer films exhibited good mechanical properties with tensile strengths in the range of 78–109 MPa, tensile modulus in the range of 1.44–1.76 GPa, and elongation at break values ranging from 11% to 24%. Electrical insulating properties of two polymer films were evaluated on the basis of dielectric constant and dielectric loss and their variation with frequency and temperature. 相似文献
14.
Wojciech Simka Tadeusz Gorewoda Roman Mazurkiewicz Ginter Nawrat 《Journal of Applied Electrochemistry》2011,41(7):809-815
Voltamperometric studies on the indirect electrochemical α-methoxylation of Boc-Pro-Gly-OMe and Boc-Val-Gly-OMe in MeOH in the presence of NaCl or NaBr as the mediator suggested that the first reaction step was a direct N-halogenation of the dipeptide by active chlorine or bromine adsorbed on the electrode surface. The kind of mediator (NaCl or NaBr), its concentration, the current density, and the applied electric charge had a significant influence on the reaction course. In the case of Boc-Pro-Gly-OMe, the use of sodium bromide was necessary to obtain a relatively high ratio of α-monomethoxylation to α,α-dimethoxylation. For Boc-Val-Gly-OMe, the selectivity for α-monomethoxylation was close to 100%, independently of the mediator. Optimisation of the selected electrolysis parameters allowed us to significantly improve the yield and selectivity of the α-methoxylation of Boc-Pro-Gly-OMe (Kardassis et al. Tetrahedron 54:3471, 1998) and to obtain good results in the α-methoxylation of Boc-Val-Gly-OMe. 相似文献
15.
Richard Vendamme Tewfik Bouchaour Tadeusz Pakula Xavier Coqueret Mustapha Benmouna Ulrich Maschke 《大分子材料与工程》2004,289(2):153-157
Summary: This paper reports the phase behavior of photochemically crosslinked poly(butyl acrylate) networks in nematic liquid crystal (LC) solvents. The swelling properties are studied as a function of temperature for two low molecular weight nematic LCs, 4‐cyano‐4′‐pentylbiphenyl (5CB) and the eutectic mixture of cyanoparaphenylenes (E7). Chemically crosslinked polymer networks were formed by the UV radiation of initial solutions of the reactive monomer, butyl acrylate, a crosslinker (hexanediol diacrylate), and a photoinitiator. To obtain different network densities, the ratio of butyl acrylate to hexanediol diacrylate was varied prior to polymerization/crosslinking reactions. Immersion in an excess of the LC solvent allowed for the measurement of size increase by polarized optical microscopy in terms of temperature. Length, width, and diagonal ratios were calculated considering swollen to dry network states of the samples. In general, swelling leads to an increase in the network size by increasing the temperature with a significant dependence on the degree of crosslinking. A large shift in the swelling ratio was found in the vicinity of the nematic to isotropic transition temperatures of the LCs.
16.
Aline Olivier Leila Benkhaled Tadeusz Pakula Bernd Ewen Andreas Best Mustapha Benmouna Ulrich Maschke 《大分子材料与工程》2004,289(12):1047-1052
Summary: This paper discusses static and dynamic mechanical properties of electron beam‐cured mixtures made of the nematic liquid crystal (LC) E7 and either tripropyleneglycol diacrylate (TPGDA) or propoxylated glycerol triacrylate (GPTA) as monomers differing essentially by their functionality. Dilution of the initial mixture with LC leads to a significant weakening of the film mechanical strength. Strong effects were found on Young modulus and rubbery state modulus. As the concentration of LC increases, these mechanical parameters drop significantly together with the glass transition temperature of the polymer showing a plasticizing effect. The results for the glass transition temperatures for the polymer and the LC were confirmed by thermograms obtained by differential scanning calorimetry.
17.
A Kuczyńska A Kosmala M Surma T Adamski 《International journal of molecular sciences》2012,13(8):10410-10423
Barley (Hordeum vulgare L.) is an important cereal crop grown for both the feed and malting industries. The allelic dwarfing gene sdw1/denso has been used throughout the world to develop commercial barley varieties. Proteomic analysis offers a new approach to identify a broad spectrum of genes that are expressed in the living system. Two-dimensional electrophoresis and mass spectrometry were applied to investigate changes in protein abundance associated with different juvenile growth habit as effect of the denso locus in barley homozygous lines derived from a Maresi × Pomo cross combination. A total of 31 protein spots were revealed that demonstrate quantitative differences in protein abundance between the analyzed plants with different juvenile growth habit, and these protein spots were selected to be identified by mass spectrometry. Identification was successful for 27 spots, and functional annotations of proteins revealed that most of them are involved in metabolism and disease/defense-related processes. Functions of the identified proteins and their probable influence on the growth habit in barley are discussed. 相似文献
18.
Tadeusz Wdka 《应用聚合物科学杂志》1989,37(3):581-594
Modified PEO (MW 6000) containing xanthate groups was used for the synthesis of block copolymers of PAN and PEO. Principal parameters affecting the synthesis were examined. To confirm the segmental structure of the obtained products, precipitation fractionation, gel permeation chromatography, infrared, and 1H nuclear magnetic resonance methods were used. The fiber-forming properties were investigated by means of rheological examination of concentrated solutions of PAN–PEO and confirmed by spinning the fibers under laboratory conditions. The physical and mechanical properties of the fibers were also determined. 相似文献
19.
Pawel Falkowski Paulina Bednarek Anna Danelska Tadeusz Mizerski Mikolaj Szafran 《Journal of the European Ceramic Society》2010,30(14):2805-2811
Obtaining highly loaded, time-stable and relatively low viscosity suspensions approaches colloidal processing to be very convenient and effective route of shaping of nanopowders. In order to obtain well dispersed, homogenous ceramic slurries, certain additives are given. Saccharides, particularly monosaccharides, as well as their derivatives, were found to be a group of effectively working processing agents in case of alumina, which has been used as a solid phase of highly loaded nanosuspensions. This class of chemical compounds can be described by a series of advantages – they are non-toxic, water-soluble, inexpensive, etc. In this paper suspensions of nano- and submicro-alumina powders with addition of d-fructose, 1-O-methyl-d-fructose, d-glucose and 3-O-acrylic-d-glucose have been studied in terms of their rheological properties, moreover the properties of as-received green bodies have been presented. 相似文献