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101.
Raluca Nicoleta Darie Ruxandra Bodirlau Carmen Alice Teaca Joanna Macyszyn Marek Kozlowski Iuliana Spiridon 《International Journal of Polymer Analysis and Characterization》2013,18(4):315-327
In the view of producing environmentally friendly materials without compromising properties, new composites containing polypropylene as a matrix and eucalyptus wood, with or without 15% of polylactic acid, were melt processed. In order to improve compatibility between components, a chemical modification of wood with toluene-2,4-diisocyanate (TDI) was realized and evidenced by changes in FT-IR and XPS spectra. The morphological, mechanical, and thermal characterizations of the obtained composites were evaluated before and after accelerating weathering. The results showed that the material comprising 15% TDI-modified wood, PP, and 15% PLA exhibited the best properties. 相似文献
102.
We obtain explicit upper bounds for the number of irreducible factors for a class of compositions of polynomials in several
variables over a given field. In particular, some irreducibility criteria are given for this class of compositions of polynomials. 相似文献
103.
Emil Ioan Muresan Spiridon Oprea Theodor Malutan Mihai Vata 《Central European Journal of Chemistry》2007,5(3):715-726
The esterification reaction of palmitic acid with epichlorohydrin catalyzed by an anionic macroporous resin was studied. Purolite
A-500 resin proved to be a very effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl palmitate. The effects of
certain parameters such as speed of agitation, catalyst particle size, catalyst loading, temperature, initial molar ratio
between reactants on the rate of reaction were studied. It was found that the overall rate is intrinsically kinetically controlled.
The structure of synthesized ester was confirmed by FTIR and 1H NMR analyses.
相似文献
104.
Maria Geba Gabriela Lisa Cristina Marta Ursescu Angelica Olaru Iuliana Spiridon Ana Lacramioara Leon Ioana Stanculescu 《Journal of Thermal Analysis and Calorimetry》2014,118(2):977-985
In order to investigate the effect of gamma rays on cultural heritage materials, samples of silk and wool fabrics were subjected to accelerated ageing testing and then irradiated with different gamma-ray doses: 10 and 25 kGy. In the data analysis, combining thermal analysis (TG and DTG), infrared spectroscopy (FTIR-ATR) and mechanical tests allowed us to explore the changes in physical and chemical features for silk and wool, in relationship to the radiation doses. This analytical protocol offers a way to examine the behaviour of the textiles made of wool and silk within museum collections and their response to gamma-rays irradiation treatment. An exposure to a dose of 10 kGy did not cause significant changes in the tested properties; however, higher doses initiated irreversible loss in the physical and chemical stability of protein-based fabrics. Increasing the irradiation dose above 10 kGy has drastic effects in the loss of elasticity and the mechanical resistance of the tested yarns. 相似文献
105.
Chitosan Based Diamond Paste Stochastic Microsensors Modified with Gold Nanoparticles Detect Hepatitis C Virus Core Antigen 下载免费PDF全文
Iuliana Moldoveanu Raluca‐Ioana Stefan‐van Staden Jacobus Frederick van Staden 《Electroanalysis》2015,27(8):1842-1846
Three types of chitosan (chitosan I (n=371–744), chitosan II (n=682–930), and chitosan III (n=868–1365)) as well as gold nanoparticles (10 nm diameter) were used to modify diamond paste for the design of new stochastic microsensors. Hepatitis C virus core antigen was used as model analyte to prove the stochastic behavior of the proposed microsensors. The microsensors cover a linear range of concentration between 40 fg/mL and 4 ng/mL. The highest sensitivity (1.38×105 s?1/mg/mL) and the lower limit of determination (40 fg/mL) were obtained for chitosan III based microsensor. The hepatitis C virus core antigen was assayed from whole blood samples with recoveries higher than 98.00 %. 相似文献
106.
We obtain explicit upper bounds for the number of irreducible factors for a class of polynomials of the form f ○ g, where f,g are polynomials with integer coefficients, in terms of the prime factorization of the leading coefficients of f and g, the degrees of f and g, and the size of coefficients of f. In particular, some irreducibility results are given for this class of compositions of polynomials. 相似文献
107.
Mihaela Alexandru Maria Cazacu Alexandra Nistor Valentina E. Musteata Iuliana Stoica Cristian Grigoras Bogdan C. Simionescu 《Journal of Sol-Gel Science and Technology》2010,56(3):310-319
Composites based on polydimethylsiloxane incorporating silica and titania were prepared by mixing polydimethylsiloxane with
proper oxides precursors, tetraethyl-orthosilicate and tetrabutyl-orthotitanate. In the presence of environmental humidity
and in acid catalysis, hydrolysis/condensation processes take place with formation of oxides and concomitantly polymer crosslinking.
Partial replacement of SiO2 in a polydimethylsiloxane/silica composite with titania (both generated in situ by sol–gel process) affects surface hydrophilicity
(evaluated by dynamic contact angle), water vapor sorption ability (determined by dynamic vapor sorption) and thermal stability.
The dielectric properties are also controlled by composition. 相似文献
108.
A series of new thiourea catalysts prepared from natural amino acids have been applied in organocatalytic asymmetric Michael additions of α-nitrocyclohexanone to nitroalkenes. The resulting addition products are formed with excellent enantioselectivities (up to an er of 98:2) in good yields (up to 90%). 相似文献
109.
A synergistic catalytic system for the first asymmetric addition of aldehydes to in situ generated prochiral oxocarbenium ions has been developed. The dual catalytic protocol allows the simultaneous activation of both electrophile and nucleophile and provides access to a variety of valuable chiral 2H-chromenes with excellent enantioselectivities. 相似文献
110.
Margareta Socaciu Carmina Plosceanu Iuliana Cuculescu I. Muşcutariu 《Phase Transitions》2013,86(4):249-257
The use is described of absorption spectroscopy for determining phase transitions in the mesogenic compound cholesteryl myristate (CM) and in binary mixtures of terephthalbis-butyl-aniline (TBBA) and cholesteryl myristate. The temperature dependence of the optical densities in the visible region at phase transitions is reported. The transition temperatures obtained with this method are in good agreement with the results obtained with other methods. 相似文献