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91.
Kapturowska AU Stolarzewicz IA Krzyczkowska J Białecka-Florjańczyk E 《Ultrasonics sonochemistry》2012,19(1):186-191
The aim of this study was to evaluate the efficiency of sonication in releasing protein from a widespread lipase-producing yeast, Yarrowia lipolytica KKP 379, and to examine the impact of ultrasound waves generated in a horn-type sonicator on the lipolytic activity of Y. lipolytica in the hydrolysis of p-nitrophenyl laurate. In this paper, we focused on a few parameters of ultrasound cell disruption, such as the time of sonication, acoustic power, storage time of the frozen yeast biomass used in sonication and the solvent used to suspend the yeast cells which were considered as the most important part in the process of obtaining a biocatalyst from Y. lipolytica for organic synthesis. The most effective additive in protein release proved to be 2% Tween 80; other ideal parameters of the process were ultrasonic power at 150 W for 15 min and 9 weeks of frozen biomass storage time. The sonication parameters, which were the best for protein release, did not seem to be the most effective for obtaining high lipolytic activity due to denaturation as an effect of cavitation. 相似文献
92.
Zbigniew Kisiel Ewa Bia?kowska Jaworska Douglas T. Petkie Ivan R. Medvedev 《Journal of Molecular Spectroscopy》2009,254(2):78-86
The analysis of the recently recorded 78-378 GHz broadband spectrum of ClONO2 has been extended to cover rotational transitions in all 14 excited vibrational states up to 650 cm−1 above the ground state. We report new measurements and analysis of the 2ν9 and 3ν9 dyads, and first assignment and analysis for the 4ν9 and 5ν9 triads. The polyad fits encompass a total of over 20 000 newly measured transition frequencies and spectroscopic constants are reported for 10 vibrationally excited states in each of 35ClONO2 and 37ClONO2. All polyads were fitted with a new coupling scheme between the perturbing states combining c-axis Coriolis and Fermi interactions. The scheme is validated by multiple tests of the physical significance of the derived parameters and it results in improved deviations of fits and significant reduction in the number of adjustable parameters. 相似文献
93.
D. Valdez-Jasso H. T. Banks M. A. Haider D. Bia Y. Zocalo R. L. Armentano & M. S. Olufsen 《advances in applied mathematics and mechanics.》2009,1(2):151-165
This paper compares two models predicting elastic and viscoelastic properties
of large arteries. Models compared include a Kelvin (standard linear) model
and an extended 2-term exponential linear viscoelastic model. Models were validated
against in-vitro data from the ovine thoracic descending aorta and the carotid
artery. Measurements of blood pressure data were used as an input to predict vessel
cross-sectional area. Material properties were predicted by estimating a set of
model parameters that minimize the difference between computed and measured
values of the cross-sectional area. The model comparison was carried out using
generalized analysis of variance type statistical tests. For the thoracic descending
aorta, results suggest that the extended 2-term exponential model does not improve
the ability to predict the observed cross-sectional area data, while for the carotid
artery the extended model does statistically provide an improved fit to the data.
This is in agreement with the fact that the aorta displays more complex nonlinear
viscoelastic dynamics, while the stiffer carotid artery mainly displays simpler linear
viscoelastic dynamics. 相似文献
94.
Tímea Kaszs Balzs ron Barth Bernadett Balzs Tekla Blga Lszl Juhsz Lszl Somsk Marietta Tth 《Molecules (Basel, Switzerland)》2022,27(6)
A catalyst-free coupling reaction between O-peracetylated, O-perbenzoylated, O-permethylated, and O-permethoxymethylated 2,6-anhydro-aldose tosylhydrazones (C-(β-d-glycopyranosyl)formaldehyde tosylhydrazones) and aromatic boronic acids is reported. The base-promoted reaction is operationally simple and exhibits a broad substrate scope. The main products in most of the transformations were open-chain 1-C-aryl-hept-1-enitol type compounds while the expected β-d-glycopyranosylmethyl arenes (benzyl C-glycosides) were formed in subordinate yields only. A mechanistic rationale is provided to explain how a complex substrate may change the well-established course of the reaction. 相似文献
95.
It is pointed out that the spin structure of leading clusters appearing in the final state of inelastic collisions at high energies influences strongly the estimate of the slope of the overlap function. It is also argued that this effect may drastically improve the agreement with experimental data. 相似文献
96.
Charge-transfer interactions in cyclophane systems are reviewed. The majority of the work covered involves intermolecular complexation, with both donor and acceptor moieties existing within the same molecule. Studies have also been performed on intermolecular complexes, mainly tetracyanoethylene:cyclophane complexes. Host-guest complexes involving charge-transfer are also discussed. Other areas covered include solvent effects, substituent effects, and theoretical calculations. 相似文献
97.
The thermal unfolding of two RNA hairpin systems derived from the aminoacyl accepting arm of Escherichia coli tRNA(Ala) that included all possible single internal mismatches mostly in the third base pair position was measured spectroscopically in 0.1 M NaCl at pH 7.5 and, in part, 5.5. The thermodynamic parameters DeltaH(o), DeltaS(o), DeltaG(o), and T(m) of a total of 36 RNA strands were determined through nonlinear curve fitting of the melting profiles (22 tetralooped 22mers and 14 heptalooped 25mers, same stem sequence). Only three of the 22mers, the A.C-containing variants, were shown to be significantly more stable at pH 5.5. A number of remarkable differences-most likely of more general relevance-between the thermodynamics of certain structurally very similar hairpin variants (e.g., G.C versus A.U, G.U versus I.U) at pH 7.5 are discussed with respect to two possible ways of helix stabilization: pronounced hydration versus low entropic penalty. Four selected 22mers were additionally analyzed in 1 M NaCl and in solvent mixtures containing ethanol, ethylene glycol, and dimethylformamide. The wealth of thermodynamic data suggest that the exothermicity DeltaH(o) and entropic penalty T x DeltaS(o) of folding are strongly dominated by the rearrangement and formation of hydration layers around the solutes, while it is well-known that the stability of folding results only from the difference (DeltaG(o)) and ratio of both parameters (T(m) = DeltaH (o)/DeltaS(o)). 相似文献
98.
Białkowska Ewa Leibler Karolina Kalinowski Marek K. 《Monatshefte für Chemie / Chemical Monthly》1976,107(4):865-870
Effect of 11 inert solvents (carbon tetrachloride, nitrobenzene, acetonitrile, sulpholane, propylene carbonate, acetone, ethyl acetate, tetrahydrofuran, dimethylformamide, dimethylsulfoxide and hexamethylphosphoramide) on the ESR spectrum of copper acetylacetonate have been studied at the temperature about 298 K. There was stated that hyperfine splitting linearly decreases with the increasing ofGutmann's donor number of solvent. This phenomenon was discussed in terms of solvent—solute interaction.
Mit 2 Abbildungen 相似文献
Mit 2 Abbildungen 相似文献
99.
Marzena BiaŁek Anna GarŁowska Ozanna Liboska 《Journal of polymer science. Part A, Polymer chemistry》2009,47(18):4811-4821
A titanium complex with [O,N,N,O]‐type tetradentate Schiff base (LTiCl2), never used before in polymerization of olefins, was immobilized on silica‐ and magnesium‐type carriers, and it was used in ethylene polymerization. The conducted research revealed that the catalytic properties of the complex LTiCl2 supported on those carriers were different for both the catalytic systems studied, and simultaneously they turned out different from those of the unsupported system. The supported catalysts require the use of Me3Al, Et3Al, or MAO as the activator to be able to offer high catalytic activities, whereas Et2AlCl is needed for the nonsupported catalyst. This finding, together with considerable changes in polymerization yields and in properties of polymers versus composition of the catalytic system, suggest that there are different types of active sites in the studied catalysts. The catalyst anchored on the carrier produced in the reaction of MgCl2·3.4EtOH with Et2AlCl is definitely the most active one within the support systems tested. Its activity remarkably increases with the increasing reaction temperature. Moreover, that catalyst does not undergo deactivation over the studied period of time, irrespective of the type of the activator used and of the process temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4811–4821, 2009 相似文献
100.
Marzena Białek Anna Pietruszka 《Journal of polymer science. Part A, Polymer chemistry》2009,47(14):3480-3489
Ethylenebis(5‐chlorosalicylideneiminato)vanadium dichloride supported on MgCl2(THF)2 or on the same carrier modified by EtnAlCl3?n, where n = 1–3, was used in ethylene polymerization in the presence of MAO or a common alkylaluminium compounds as a cocatalyst. The support type alter vanadium loading and also change the characteristic of the catalytic active sites. Et2AlCl is the best activator for a catalyst which has been immobilized on a nonmodified support, whereas the systems which contain a carrier which has been modified by an organoaluminium compound reveal the highest activity in conjunction with MAO. That difference, together with different temperature effects on polymerization efficiency (i.e., decrease and increase of catalytic activity for increasing temperatures, respectively) suggest the formation of different types of active sites in the catalytic systems supported on modified and nonmodified magnesium carrier. However, all supported precatalysts possess a long lifetime, still being active towards ethylene polymerization after 2 h. All the systems yield wide MWD polyethylene, while bimodal MWD is found for some part of analyzed samples. Polyethylene with bimodal particle size distribution is formed with the system which contain modified carriers at higher temperatures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3480–3489, 2009 相似文献