Search results for "Maxim"

1988

Phase diagrams were calculated for flowing solutions of polystyrene in trans-decahydronaphthalene assuming that the energy (Es) stored in the sheared state has to be added to the Gibbs energy of mixing; Es is computed from viscometric data (flow curves). The resulting phase diagrams exhibit two maxima in most of the cases instead of only one for the stagnant solutions. A comparison with experimental data (Part 1) shows that the calculated demixing behaviour agrees well for moderate shear rates and concentrations of the polymer. Deviations in the semidilute region, particularly for higher values, are a consequence of the fact that so far no reliable theoretical relation has been given for th…

A thermodynamic analysis on the coincidence of extrema conditions in the sorption equilibrium for ternary polymer systems

1993

Flory-Huggins theory of polymer solutions has been used to express the condition of extrema values in the total sorption, as well as the inversion point in the preferential adsorption parameters for termary polymer systems. Two approaches have been followed, the first considers the binary and ternary interaction parameters independent of polymer concentration and solvent composition. In the second one, this dependence has been introduced. Our attention is focused on the volume fraction of solvent mixture dependence of the above parameters, in order to confirm or not the coincidence between the extrema values and the inversion point. Several cosolvent and cononsolvent ternary polymer systems…

Prediction of maxima and minima in the curve of total sorption parameter in ternary polymer systems. Influence of ternary interaction parameter

1993

Flory-Huggins theory modified by Pouchly has been applied to predict maxima and minima in the curve of total sorption in ternary polymer systems formed by a polymer and two liquids. In this work, different diagrams based on experimental magnitudes easily obtained such as the difference in affinities of liquids, solvents and non solvents, and the solvent molar volume ratio. Total sorption parameter has been considered to be the decisive magnitude to define extrema conditions in both cosolvent and cononsolvent ternary polymer systems. The theoretical prediction is not altered by the inclusion of ternary interactions. Different examples of ternary systems dealing with vinyl polymers and polydi…

Crystal structure of C-2-benzo-thia-zole-N-methyl-nitrone.

2015

The molecule of the title compound {systematic name:N-[(benzothiazol-2-yl)methylidene]methylamineN-oxide}, C9H8N2OS, is close to planar [maximum deviation from the mean plane = 0.081 (2) Å], its conformation being stabilized by a strong intramolecular attractive S...O interaction [2.6977 (16) Å]. In the crystal, molecules are linked into centrosymmetric dimers by pairs of weak C—H...O hydrogen bonds.

Über den einfluß des lösungsmittels beim thermischen zerfall des azoisobuttersäuredinitrils

1967

Der Zerfall des Azoisobuttersauredinitrils wurde in 10 verschiedenen Losungsmitteln kinetisch untersucht. Er ist streng eine Reaktion erster Ordnung. Die Zerfallsgeschwindigkeit ist in den einzelnen Losungsmitteln verschieden. Der maximale Unterschied betragt bei 60°C 40% (Malonsaurediathylester/Cyclohexanol), entsprechend einer Differenz der Freien Enthalpie des Ubergangszustandes von 250 cal/Mol. Die starkeren Anderungen der Aktivierungsenthalpie bis zu 1,5 kcal/Mol werden durch entsprechende Anderungen der Entropie des Ubergangszustandes kompensiert. The thermal decomposition of azo-bis-isobutyronitrile in a series of 10 solvents was investigated. The reaction is strictly of first order.…

Soda-AQ pulping of reed canary grass

2001

Abstract Delignification of reed canary grass (Phalaris arundinacea L.) was carried out by conventional soda-anthraquinone (AQ) pulping under varying conditions selected according to an orthogonal experimental design with four factors (cooking parameters) at three levels each L9 (34). The influence of these four parameters, i.e. effective alkali, EA (12, 15, and 18% on oven dried (o.d.) reed, as NaOH), maximum temperature (145, 155, and 165°C), time to maximum temperature (70, 90, and 110 min), and time at maximum temperature (0, 15, and 30 min) on the pulp properties (yield, kappa number, and viscosity) was studied. Results indicated that, with respect to delignification, EA was the most i…

Electronic Spectra of 2,2‘-Bithiophene and 2,2‘:5‘,2‘ ‘-Terthiophene Radical Cations:  A Theoretical Analysis

2001

Analysis of the electronic spectra of 2,2‘-bithiophene and 2,2‘:5‘,2‘ ‘-terthiophene radical cations has been performed by using multiconfigurational second-order perturbation theory (CASPT2). Atomic natural orbital (ANO) type basis sets of split valence quality, including polarization functions on all heavy atoms, have been used. In agreement with experimental data, in the energy range below the lowest optically allowed transition of the respective neutral system, theoretical results predict two main absorption bands for both cations. The 22Au and 32Au states computed at 1.94 and 2.80 eV, respectively, are related to the corresponding band maxima recorded for bithiophene cation. The 12B1 s…

2-(3,5-Dimethyl-1H-pyrazol-1-yl)-2-hy-droxy-imino-N'-[1-(pyridin-2-yl)ethyl-idene]acetohydrazide.

2012

In the title compound, C14H16N6O2, the dihedral angles formed by the mean plane of the acetohydrazide group [maximum deviation 0.0629 (12) A] with the pyrazole and pyridine rings are 81.62 (6) and 38.38 (4)° respectively. In the crystal, mol­ecules are connected by N—H⋯O and O—H⋯N hydrogen bonds into supra­molecular chains extending parallel to the c-axis direction.

Influence of time-of-day-specific same-session combined endurance and strength training on maximal and submaximal endurance parameters

2015

Endurance and strength training are often performed concurrently by both elite athletes and recreational individuals. The question of whether the order of exercises or training at certain daytimes yields to different adaptations in endurance and strength parameters, when endurance and strength training are combined into a single training session, has received limited scientific attention. Moreover, effects on cardiorespiratory and neuromuscular variables after same-session concurrent training have shown conflicting results, particularly regarding exercise sequence or time-of-day characteristics. The purpose of the present study was to examine the effect of time-of-day-specific same- session…

Palaeoclimate has a major effect on the diversity of endemic species in the hotspot of mountain biodiversity in Tajikistan.

2021

AbstractIn a period of ongoing climate changes, identifying drivers of overall and endemic species diversity is a key element in constructing new ecological patterns and determining the main goals of conservation. Such studies are especially crucial if they concern biodiversity hotspot areas. In this study, we explore patterns and drivers of plant endemism (the proportion of endemic plant species to overall plant species richness; PE) in Tajikistan. We used three groups of climatic measures featuring the contemporary and glacial climates as well as climatic changes since the Last Glacial Maximum in the Pleistocene (LGM). To explore relationships between PE and climatic groups, and the most …