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981.
982.
Urszula Domańska Kamil Paduszyński Zuzanna Żołek-Tryznowska 《The Journal of chemical thermodynamics》2011,43(2):167-171
(Liquid + liquid) phase equilibria (LLE) of binary mixtures containing hyperbranched polymer Boltorn® H2004 and n-alkanes (n-hexane, n-heptane, n-octane, and n-decane) were studied over the temperature range from about (260 up to 360) K. The polymer is partially miscible with n-alkanes and the solubility decreases with an increase of the chain length of the solvent. Corresponding LLE phase diagrams including spinodal and binodal (liquid + liquid) coexistence curves were calculated in terms of the statistical mechanics – based on the lattice-cluster theory, based only on the upper critical solution temperature, and the polymer chain architecture. The results show semi-qualitative agreement of predicted and experimental equilibrium compositions and temperatures. Boltorn® H2004 reveals complete miscibility in the liquid phase with alcohols (C1–C8), aromatic hydrocarbons (benzene, toluene, and thiophene), and ethers (methyl tetra-butyl ether, ethyl tetra-butyl ether, and tetrahydrofurane). 相似文献
983.
O. V. Reshetnyak E. P. Koval’chuk J. Błażejowski 《Russian Journal of Electrochemistry》2011,47(10):1111-1118
A short review is dedicated to the role of molecular oxygen and its active forms in generation of electrochemiluminescence
(ECL). It is shown at the example of such widely used luminogens as luminol, lucigenin, acridine esters, acridane, and indoles
that the role of O2 and its active forms, such as hydrogen peroxide, superoxide and hydroperoxide radicals in generation of ECL by organic compounds
is largely reduced to oxidation of the initial luminogen or intermediates of its partial electrochemical preoxidation/prereduction.
Such intermediates are most often particles in the doublet state (radical-cation, radical-anion, or free radicals) that form
unstable emitter precursors of peroxide (dioxetanone) type under interaction with O2, hydrogen peroxide, or other active oxygen forms. It is also shown that the product of secondary transformations of active
oxygen forms is singlet oxygen that may also be a radiation source as a result of cooperative transitions. 相似文献
984.
A simple and sensitive spectrophotometric method for the determination of L-ascorbic acid with leuco crystal violet is proposed. The determination is based on the oxidation of analyte by potassium
iodate. The colourless oxidation products were formed in the quantity equivalent to iodide ions. The iodide ions react with
the excess of iodate ions in acidic medium, to form free iodine which oxidized leuco crystal violet (LCV) to the liberated crystal violet (CV
+) dye, showing maximum absorption at 588 nm. The absorbance was measured at pH of 4.1–4.2 in 1 cm cuvettes. Beer’s law was
obeyed in the concentration range 0.5–4.0 μg/mL. The molar absorptivity of the coloured compound is 4.14 × 104 L/mol cm for L-ascorbic acid. The analytical parameters were optimized and the method was successfully applied to the determination of L-ascorbic acid in pharmaceuticals. The results were compared with those obtained by methods proposed in Polish Standard. 相似文献
985.
Maślanka A Krzek J Stolarczyk M Walczak M Głogowska A 《Journal of AOAC International》2011,94(6):1791-1799
Stability of clonazepam, diazepam, haloperidol, and doxepin was determined in acidic solutions. In addition, determination of the kinetic and thermodynamic properties of this stability was carried out. Reaction rate constants (k), half-life times (t(0.1) and t(0.5)), and activation energy (Ea) were estimated for the drugs, which differed in polarity expressed with log P values. It was observed that estimated Ea values increased from 42.13 to 125.03 kJ/mol with an increase of lipophilicity (log P) beginning from the most hydrophilic drug (clonazepam, 2.70 log P) to the most lipophilic drug (doxepin, 4.10 log P). All degradation products were studied using an HPLC/electrospray ionization-MS technique in the positive ionization mode. 相似文献
986.
Nowicka B Bałanda M Gaweł B Ćwiak G Budziak A Łasocha W Sieklucka B 《Dalton transactions (Cambridge, England : 2003)》2011,40(12):3067-3073
Methanol adsorption into the porous 2D bimetallic coordination network {[Ni(cyclam)](3)[W(CN)(8)](2)}(n) (cyclam = 1,4,8,11-tetraazacyclotetradecane) causes significant modification of its structure and magnetic properties. Fully reversible transformations between the three states of the network: anhydrous, hydrated and methanol-modified are observed with the transition to the magnetic ordered state at T(c) equal to 4.9 K, 8.3 K and 11.4 K respectively. All three phases have a metamagnetic character but the methanol-modified one most easily turns to ferromagnetic and shows a hysteresis loop with coercivity field of 250 Oe. The differences in magnetic behaviour of the anhydrous and guest-induced forms of the compound are discussed in terms of changes in the structure: CN-bridge geometry and distance between the layers. 相似文献
987.
Chien CC Zhang G Hwu Y Liu P Yue W Sun J Li Y Xu H Xue H Xu LX Wang CH Chen N Lu CH Lee TK Yang YC Lu YT Ching YT Shih TF Yang PC Je JH Margaritondo G 《Analytical and bioanalytical chemistry》2011,401(3):827-835
Refractive-index (phase-contrast) radiology was able to detect lung tumors less than 1 mm in live mice. Significant micromorphology differences were observed in the microradiographs between normal, inflamed, and lung cancer tissues. This was made possible by the high phase contrast and by the fast image taking that reduces the motion blur. The detection of cancer and inflammation areas by phase contrast microradiology and microtomography was validated by bioluminescence and histopathological analysis. The smallest tumor detected is less than 1 mm(3) with accuracy better than 1 × 10(-3) mm(3). This level of performance is currently suitable for animal studies, while further developments are required for clinical application. 相似文献
988.
989.
Hanć A Komorowicz I Iskra M Majewski W Barałkiewicz D 《Analytical and bioanalytical chemistry》2011,399(9):3221-3231
The study was aimed to evaluate the influence of the vascular disease, atherosclerotic obliterans (AO), on the location and
concentration of elements in the arterial wall and serum. Use of a modern method for studying element’s concentration and
distribution in samples of clinical material, i.e. laser ablation inductively coupled plasma mass spectrometry, is presented.
Elements are not equally distributed between the inner (intima) and the outer (media + adventitia) layer of the arterial wall.
Among the studied elements, calcium was found to have an unquestionable role in the calcification of the wall. Increased concentration
of calcium found in the inner part of the atherosclerotic arterial wall and in the plaque, as compared to the control arterial
wall samples, demonstrates the unquestionable role of this element in the calcification of the wall observed in AO. Applied
chemometric methods were useful for demonstrating the differences in the element’s concentration in blood serum and the arterial
wall samples between AO and the control group. 相似文献
990.
Mieczysław Mastyło 《Potential Analysis》2011,35(4):301-328
We define a general variant of the modulus of smoothness in metric spaces and show that under mild condition it is equivalent
to the K-functional of a couple of Besov type spaces which in special cases coincide with spaces defined by Korevaar and Schoen. We
prove various symmetrization inequalities which involve the modulus, the K-functional and the isoperimetric estimators. We also characterize the Hajłasz-type Sobolev spaces defined not necessarily
on doubling measure spaces by means of generalized Poincaré inequalities. This require to study of some variants of the Fefferman–Stein
sharp functions as well as the Hardy–Littlewood maximal operators. 相似文献