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31.
Garry Kerch Alexander Glonin Janis Zicans Remo Merijs Meri 《Journal of Thermal Analysis and Calorimetry》2012,108(1):185-189
The effect of bread making methods on bound water migration from crumb to crust and moisture redistribution during bread storage
at room temperature was studied. Comparative analysis of water behavior in bread crusts and crumbs was performed using differential
scanning calorimetry method. Water vaporization enthalpies and temperatures of water vaporization peaks were determined and
compared for bread produced by a single stage, straight dough method and bread produced by a two stage, sponge-and-dough method.
The effect of chitosan on the crust and the crumb properties was analyzed for the breads produced by both methods. 相似文献
32.
M. Hokka J. Kokkonen J. Seidt T. Matrka A. Gilat V.-T. Kuokkala 《Experimental Mechanics》2012,52(2):195-203
Mechanical properties of most metallic materials can be improved by reducing their grain size. One of the methods used to
reduce the grain size even to the nanometer level is the severe plastic deformation processing. Equal Channel Angular Pressing
(ECAP) is one of the most promising severe plastic deformation processes for the nanocrystallization of ductile metals. Nanocrystalline
and ultrafine grained metals usually have significantly higher strength properties but lower tensile ductility compared to
the coarse grained metals. In this work, the torsion properties of ECAP processed ultrafine grained pure 1070 aluminum were
studied in a wide range of strain rates using both servohydraulic materials testing machines and Hopkinson Split Bar techniques.
The material exhibits extremely high ductility in torsion and the specimens did not fail even after 300% of strain. Pronounced
yield point behavior was observed at strain rates 500 s−1 and higher, whereas at lower strain rates the yielding was continuous. The material showed slight strain softening at the
strain rate of 10−4 s−1, almost ideally plastic behavior at strain rates between 10−3 s−1 and 500 s−1, and slight but increasing strain hardening at strain rates higher than that. The tests were monitored using digital cameras,
and the strain distributions on the surface of the specimens were calculated using digital image correlation. The strain in
the specimen localized very rapidly after yielding at all strain rates, and the localization lead to the development of a
shear band. At high strain rates the shear band developed faster than at low strain rates. 相似文献
33.
Cross‐coupling reactions in water using ionic liquid‐based palladium(II)–phosphinite complexes as outstanding catalysts
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Nermin Meriç Murat Aydemir Uğur Işik Yusuf Selim Ocak Khadichakhan Rafikova Salih Paşa Cezmi Kayan Feyyaz Durap Alexey Zazybin Hamdi Temel 《应用有机金属化学》2014,28(11):818-825
Two new phosphinite ligands based on ionic liquids [(Ph2PO)C7H14N2Cl]Cl ( 1 ) and [(Cy2PO)C7H14N2Cl]Cl ( 2 ) were synthesized by reaction of 1‐(3‐chloro‐2‐hydoxypropyl)‐3‐methylimidazolium chloride, [C7H15N2OCl]Cl, with one equivalent of chlorodiphenylphosphine or chlorodicyclohexylphosphine, respectively, in anhydrous CH2Cl2 and under argon atmosphere. The reactions of 1 and 2 with MCl2(cod) (M = Pd, Pt; cod = 1,5‐cyclooctadiene) yield complexes cis‐[M([(Ph2PO)C7H14N2Cl]Cl)2Cl2] and cis‐[M(Cy2PO)C7H14N2Cl]Cl)2Cl2], respectively. All complexes were isolated as analytically pure substances and characterized using multi‐nuclear NMR and infrared spectroscopies and elemental analysis. The catalytic activity of palladium complexes based on ionic liquid phosphinite ligands 1 and 2 was investigated in Suzuki cross‐coupling. They show outstanding catalytic activity in coupling of a series of aryl bromides or aryl iodides with phenylboronic acid under the optimized reaction conditions in water. The complexes provide turnover frequencies of 57 600 and 232 800 h?1 in Suzuki coupling reactions of phenylboronic acid with p‐bromoacetophenone or p‐iodoacetophenone, respectively, which are the highest values ever reported among similar complexes for Suzuki coupling reactions in water as sole solvent in homogeneous catalysis. Furthermore, the palladium complexes were also found to be highly active catalysts in the Heck reaction affording trans‐stilbenes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
34.
Sulfite, sulfate, sulfide and thiosulfate ions are separated by high-performance liquid chromatography under acidic conditions on commercial low-capacity silica-based and resin-based anion-exchange columns with potassium hydrogenphthalate as the eluent. The ions are detected by using indirect ultraviolet absorption or conductivity detectors. The effects of concentration, pH and flow rate of the eluent on the retention times of sulfur anions are reported. The resin-based column is preferable to the silica-based column for separations of sulfur anions. 相似文献
35.
This work is to study the removal of phenol from aqueous solutions by adsorption using three different adsorbents, clinoptilolite, montmorillonite, and hydrotalcite (HT). Except for montmorillonite, the other adsorbents were treated. Clinoptilolite was modified using cetyltrimethylammonium bromide (CTAB) and hydrotalcite was calcined by heating to 550C. Adsorption isotherms of phenol on all of the mentioned adsorbents was determined by using the batch equilibration technique and indicated that, the adsorption behavior could be modelled by using the Modified Freundlich equation. The differences observed in the isotherms were explained by the variations in adsorbent-adsorbate interactions under the effects of the different surface structures of adsorbents and the pH dependent ionization behavior of phenol. Calcined hydrotalcite (HTC) was found to be the best among the studied adsorbents since it can adsorb 52% of phenol from a solution containing initially 1 g/L phenol for the 1/100 adsorbent solution ratio while the others can adsorb only 8% of phenol for the same concentration and adsorbent solution ratio. 相似文献
36.
Raimo A. Ketola Jari T. Kiuru Juha T. Kokkonen Tapio Kotiaho 《Analytica chimica acta》2006,562(2):245-251
A temperature-programmed desorption (TPD) device connected to a mass spectrometer was used to detect volatile organic compounds from air samples. The main aim was to develop an analytical method, by which both non-polar and polar organic components can be detected in the same run. In TPD, the adsorbed compounds are desorbed from the resin more slowly than in the conventional trapping techniques, such as purge-and-trap technique, in which the resin is flash-heated and the compounds are desorbed at the same time to a cryogenic trap or an analytical column. In TPD, the adsorbent resin acts also as an analytical column. In this way it is possible to obtain more rapid analysis, and also a more simple instrumentation, which can be used on-line and on-site. In this work, a new version of TPD device, which uses a resistor for heating and a Peltier element for rapid cooling, was designed and constructed. Various adsorbent resins were tested for their adsorption and desorption properties of both polar and non-polar compounds. When using a mixture of adsorbent resins, Tenax TA and HayeSep D, it was possible to analyze both polar, low-molecular weight compounds, such as methanol and ethanol, and non-polar volatile organic compounds, such as benzene and toluene, in the same run within 15 min including sampling. The same TPD principle was also tested using a Fourier transform infrared spectrometer as an analytical instrument, and the results showed that it was possible to obtain a separation of similar compounds, such as hexane and heptane, and still retaining the same sensitivity as the original on-line FTIR instrument. 相似文献
37.
Yacine Chitour Mauricio Godoy Molina Petri Kokkonen Irina Markina 《Journal of Geometric Analysis》2016,26(4):2542-2562
We study the control system of a Riemannian manifold M of dimension n rolling on the sphere \(S^n\). The controllability of this system is described in terms of the holonomy of a vector bundle connection which, we prove, is isomorphic to the Riemannian holonomy group of the cone C(M) of M. Using Berger’s list, we reduce the possible holonomies to a few families. In particular, we focus on the cases where the holonomy is the unitary and the symplectic group. In the first case, using the rolling formalism, we construct explicitly a Sasakian structure on M; and in the second case, we construct a 3-Sasakian structure on M. 相似文献
38.
P S Kokkonen W M Niessen U R Tjaden J van der Greef 《Journal of chromatography. A》1991,565(1-2):265-275
A specific method for the determination of erythromycin 2'-ethylsuccinate (EM-ES) in plasma is described. The method involves a liquid-liquid extraction procedure followed by the analysis of extracts using phase-system switching (PSS) continuous-flow fast atom bombardment (CF-FAB) liquid chromatography-mass spectrometry (LC-MS). In PSS EM-ES is enriched after analytical separation on a short trapping column, from which it is desorbed to the LC-MS interface. In this way, favourable mobile phases can be used for the LC separation and for the MS detection. Using the PSS approach a flow-rate reduction from 1.0 ml/min in the LC system to 15 microliters/min going into the mass spectrometer was achieved without splitting. The determination limit for EM-ES was 0.1 microgram/ml. 相似文献
39.
40.
N. Lilichenko R. D. Maksimov J. Zicans R. Merijs Meri E. Plume 《Mechanics of Composite Materials》2008,44(1):45-56
The preparation of an environmentally friendly nanocomposite based on plasticized potato starch and unmodified montmorillonite
clay is described. Data on the influence of montmorillonite concentration on the mechanical properties of the materials obtained
are reported. The effective elastic constants of the nanocomposites are calculated. The calculation results are compared with
experimental data. The influence of montmorillonite content on the moisture permeability is also investigated.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 1, pp. 61–76, January–February, 2008. 相似文献