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1.
Sablinskas V Hegelund F Ceponkus J Bariseviciute R Aleksa V Nelander B 《The journal of physical chemistry. A》2005,109(39):8719-8723
Ozonization reaction of ethene in neat film at 77 K was performed. Separation of ethene secondary ozonide from the other products of the reaction was performed by continuous pumping of the reactor. Only the products, which evaporated from the walls of the reactor at 185 K, were transferred to the gas cell. The high-resolution infrared absorption spectrum of gaseous ethene secondary ozonide (C(2)H(4)O(3)) in a static gas long-path absorption cell has been recorded in the 900-1100 cm(-1) spectral region at 185 K. The spectral resolution was 0.003 cm(-1). Analyses of the nu(7)(A) band at 1037.0 cm(-1), the nu(8)(A) band at 956.1 cm(-1), and the nu(18)(B) band at 1082.1 cm(-1) have been performed using the Watson Hamiltonian model (A, reduction; III(r), representation). A set of ground-state rotational and quartic centrifugal distortion constants have been obtained, and upper state spectroscopic constants have been determined for the bands investigated. A local resonance observed in nu(18) is explained as c-Coriolis interaction with nu(10) + nu(11). 相似文献
2.
Ruta Bariseviciute Justinas Ceponkus Alytis Gruodis Valdas Sablinskas 《Central European Journal of Chemistry》2006,4(4):578-591
Ozonization reaction of simple alkenes was studied by means of FT infrared absorption gas spectroscopy. The reaction was performed
at 95 K in neat films of the reactants. IR absorption spectra of the gaseous products were recorded. The spectra were analyzed
combining experimental results with theoretical calculations performed at B3LYP 6-311++G (3df, 3pd) level. We found that among
all theoretically predicted conformers of propene secondary ozonide, only one which has the O-O half-chair configuration for
the five membered ring and the radical attached in the equatorial position was present in the sample. Samples of 1-butene and 1-heptene secondary ozonides consist from two conformers of very
similar energy (ΔH=0.3 kJ/mol). The most stable conformer for both ozonides is the one with O-O half-chair configuration of the five membered
ring and the radical attached in equatorial position and the aliphatic chain in gauche position. The second stable conformer has the aliphatic chain in anti position. 相似文献
3.
According to current history of science, Levi-Civita introduced parallel transport solely to give a geometrical interpretation to the covariant derivative of absolute differential calculus. Levi-Civita, however, searched a simple computation of the curvature of a Riemannian manifold, basing on notions of the Italian school of mathematical physics of his time: holonomic constraints, virtual displacements and work, which so have a remarkable, if not dominant, role in the origin of parallel transport. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
Ruta Pribuisiene Virgilijus Uloza Limas Kupcinskas Laimas Jonaitis 《Journal of voice》2006,20(1):128-136
The aim of the study was to outline the multidimensional perceptual, subjective, and instrumental acoustic voice changes in the group of reflux laryngitis (RL) patients. Data of multidimensional voice assessment of 108 RL patients and 90 healthy persons of the control group were subjected to comparative analysis. A slight hoarseness according to the GRB (G-grade, R- rough, B-breathy) scale was prevailing in the RL patients group. Statistically significant difference (P < 0.001) between RL patients group and the control group was found of all voice parameters measured, with the patients having worse results--increased mean jitter, shimmer, normalized noise energy, voice handicap index (VHI), and decreased parameters of phonetogram. The results of the study demonstrated that multidimensional voice assessment documented deteriorated voice quality and restricted phonation capabilities in the tested group of RL patients. 相似文献
5.
The objective of this research work was to investigate the kinetics of esterification of acetic acid with n-butanol through the variation of experimental parameters. The reaction mixture was catalyzed heterogeneously by a sulfonated catalyst in batch mode of operation. The catalyst was prepared from abundantly available agro-waste, Cajanus cajan husk by chemical activation process, which produces a carbon-based solid catalyst with high surface area. The catalyst was characterized by a Brunauer-Emmet-Teller surface analyzer and Fourier transform infrared spectroscopy to know the surface morphology. Process parameters such as contact time, reaction temperature, and catalyst loading, which can influence the extent of conversion of reactants, were studied. Furthermore, the kinetic investigation was also carried out to estimate the kinetic parameters for uncatalyzed and catalyzed reaction using the second-order pseudo-homogeneous (P-H), Eley-Rideal (E-R), and Langmuir-Hinshelwood (LH) kinetic models for this research work. The kinetic parameters such as activation energy, preexponential factor, and the thermodynamic parameters such as enthalpy and entropy were estimated for uncatalyzed and catalyzed reactions using these three models. The process conditions were optimized for catalyzed and uncatalyzed reactions to obtain the maximum product yield by minimizing root mean square error of each experimental data using the MS-excel solver tool. Thus, this study reveals the high potential of an agro-waste, Cajanus cajan husk as raw material for the synthesis of catalyst. The results show that the E-R model is more appropriate for predicting the dynamic data of an esterification reaction, as the forward rate of reaction estimated using the E-R model are more modified than P-H and L-H models. 相似文献
6.
Ruta Lazauskaite Egle Stanislovaityte Juozas V. Grazulevicius 《Monatshefte für Chemie / Chemical Monthly》2008,10(4):887-893
An absorbance probe method was used for the investigation of photolysis of cationic photoinitiators. The rates of the photolysis
of diphenyliodonium hexafluorophosphate (DPIH), diphenyliodonium tetrafluoroborate (DPIB), di(tert-butylphenyl)iodonium tetrafluoroborate (DTIB), di(tert-butylphenyl)iodonium bromate (DTIBr), triphenylsulfonium hexafluorophosphate (TPS) and cyclopropyldiphenylsulfonium tetrafluoroborate (CPS) were studied in the presence of acid indicator quinaldine red (QR) in acetonitrile. Diphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate showed the highest photolysis
rate. Photopolymerization of 1,3-di(9-carbazolyl)-2-propanol glycidyl ether (DCPGE) initiated with the iodonium and sulfonium salts in bulk and in solution was studied. It was established that the highest
initial rate of polymerization is characteristic of DCPGE photopolymerization initiated with DPIH and TPS in bulk. The oligomers of DCPGE of number average molecular weight (
[`(Mn)]\overline{M_n}
) ranging from 710 to 1220 were obtained in these reactions in bulk and those with
[`(Mn)]\overline{M_n}
ranging from 1300 to 1600 were obtained in solution. 相似文献
7.
8.
Gediminas Braziulis Gytautas Janulevicius Ruta Stankeviciute Arturas Zalga 《Journal of Thermal Analysis and Calorimetry》2014,118(2):613-621
The preparation and characterization of the M′–Mo–O nitrate–tartrate (M′ = Mg, Ca, Sr, and Ba) gels, which were produced by the simple aqueous sol–gel method and calcined at 500, 600, 700, 800, 900, and 1,000 °C temperatures are reported. The crystalline alkaline earth metal molybdates (MgMoO4, CaMoO4, SrMoO4, and BaMoO4) and as-prepared M′–Mo–O nitrate–tartrate gels investigated by thermal analysis (TG/DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). TG/DSC analysis showed the possible decomposition mechanism of synthesized gels. XRD studies allowed the identification of main types of crystalline structures in the MgMoO4, CaMoO4, SrMoO4, and BaMoO4 systems. Moreover, SEM analysis revealed the changes of surface morphology of the final compounds depending on annealing temperatures. 相似文献
9.
Patrizia Trovalusci Danilo Capecchi Giuseppe Ruta 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(11):981-997
This paper presents an overview of the origin of multiscale approaches in mechanics. While the pioneer molecular models of
linear elastic bodies by Navier, Cauchy and Poisson were contradicted by experiments, the phenomenological energetic approach
by Green still seems suitable for simple materials only. Voigt’s molecular model, here reinterpreted in the light of contemporary
mechanics, reconciled the two approaches providing a conceptual guideline for developing constitutive models based on a direct
link between continuum and discrete solid mechanics. Such a theoretical background proves to be especially suitable for new
complex materials. An example referred to masonry-like materials is given. 相似文献
10.
Straksys Antanas Kavleiskaja Tatjana Gruskiene Ruta Badokas Kazimieras Sereikaite Jolanta 《Cellulose (London, England)》2022,29(16):8705-8718
Cellulose - The study aimed to propose a new system based on xylan for β-carotene delivery into aqueous environments. The xylan fraction of low molecular weight of... 相似文献