Experimental observation of rotational Doppler broadening in a molecular system

The first experimental evidence of rotational Doppler broadening in photoelectron spectra, reported here, show good agreement with recently described theoretical predictions. The dependence of the broadening on temperature and photoelectron kinetic energy is quantitatively predicted by the theory. The experiments verify that the rotational contributions to the linewidth are comparable to those from translational Doppler broadening and must be considered in the analysis of high-resolution photoelectron spectra. A classical model accounting for this newly observed effect is presented.     

On Selfadjoint Homogeneous Operators

We study unbounded selfadjoint operators that are unitarily equivalent to their affine transformation. We investigate transformation properties of an operator-valued M-function associated with given affine-invariant operator as well as spectral properties of operators that occur in that investigation.     

Chemical, antioxidant and antimicrobial investigations of Pinus cembra L. bark and needles

The chemical constituents and biological activity of Pinus cembra L. (Pinaceae), native to the Central European Alps and the Carpathian Mountains, are not well known. The aim of the present work was to examine the phenolic content, antioxidant and antimicrobial effects of hydromethanolic extracts of Pinus cembra L. bark and needles. Bark extract had higher concentrations of total phenolics (299.3 vs. 78.22 mg gallic acid equivalents/g extract), flavonoids (125.3 vs. 19.84 mg catechin equivalents/g extract) and proanthocyanidins (74.3 vs. 12.7 mg cyanidin equivalents/g extract) than needle extract and was more active as a free radical scavenger, reducing agent and antimicrobial agent. The EC?? values in the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) and reducing power assays were 71.1, 6.3 and 26 mg/mL for bark extract and 186.1, 24 and 104 mg/mL for needle extract, respectively. In addition, needle extract showed ferrous ions chelating effects (EC?? = 1,755 μg/mL). The antimicrobial effects against Staphylococcus aureus, Sarcina lutea, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans were assessed by the agar diffusion method. Both extracts (4 mg/well) were active against all the microorganisms tested; bark extract showed higher inhibition on all strains. These results indicate that Pinus cembra L. bark and needles are good sources of phytochemicals with antioxidant and antimicrobial activities.     

Etude par desorption thermique programmee des proprietes des argiles modifiees

The present work tries to emphasize the effect of acid/basis properties of montmorillonite type clays by ion exchange with cations of different natures. The acidity and basicity measuring was made by thermo programated desorption (TPD)1,2, using ammonia like basis agent and carbon dioxide like acid agent. With TPD method we can determine acid/basis proprietes by measuring of the quantity of the ammonia and carbon dioxide termodesorbed. Clays are crystalline aluminosilicates, similar with the zeolyts, who presents the property of ion exchanging. That propriety can be applicated for pollutants cations from aquatic solutions. Ion exchanging propriety depends of a lot of factors: the cation nature, the valence and the ionic ray of the cation present in the impregnated solution. That's an advantage for depollution process of heavy metals by fixing of these metals by montmorillonite structure. By using TPD metod we can obtaine a caracteristic diagram. This revised version was published online in July 2006 with corrections to the Cover Date.     

Circularly polarized x rays: another probe of ultrafast molecular decay dynamics

Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s → a(1g)* inner-shell excitation by circularly polarized x rays in SF(6). In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.     

EPR spectroscopy determination of the rate constants for addition of [O4S]•– radical anion to double bonds

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Cyclocondensation of 2-phenacyl-1H-benzimidazole with acylhydrazines: Synthesis and tautomerism of 2-(pyrazol-4-yl)-1H-benzimidazoles

The previously unknown 2-(pyrazol-4-yl)benzimidazoles containing aryl groups in the pyrazolyl ring have been obtained by the reaction of 2-phenacyl-1H-benzimidazole with aroylhydrazines. The compounds with nitrophenyl and pyridyl substituents in the pyrazole ring show pyrazolyl tautomerism with differences in the¹H NMR spectra. A semi-empirical method is proposed to determine the tautomeric composition of the synthesized pyrazoles.Institute of Organic Chemistry, Ukraine National Academy of Sciences, Kiev 253660; e-mail: iochkiev@sovam.com. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1512–1518, November, 1999.     

A Study of cryostructuring of polymer systems. 41. Complex and composite poly(vinyl alcohol) cryogels containing soluble and insoluble forms of chitosan,respectively

Complex macroporous poly(vinyl alcohol) (PVA) cryogels have been obtained by cryogenic treatment (freezing at–20°C for 12 h followed by defrosting at a rate of 0.03°C/min) of PVA–chitosan hydrochloride mixed solutions. The subsequent alkaline treatment of the cryogels has resulted in the transformation of the water-soluble salt form of chitosan into its insoluble basic form, which coagulates inside the bulk of the continuous phase of PVA cryogel into small particles with sizes of 2–5 µm. In the resulting composite cryogels, these particles play the role of an “active” filler, which increases the rigidity and heat endurance of the gel material. It has been shown that the sorption capacity of such chitosan particles entrapped into the bulk of composite cryogels with respect of bivalent copper ions is noticeably higher than the sorption capacity of ground chitosan particles incorporated as a discrete filler into the continuous phase PVA cryogels. The study of the properties of PVA–chitosan hydrochloride mixed solutions revealed that these polymers are, to a large extent, compatible with one another in a common solvent at a low ionic strength. Therefore, liquidliquid phase separation of these systems due to the thermodynamic incompatibility of macromolecules of different natures is observed only upon increasing the ionic strength by adding a low-molecular-mass salt (NaCl, 0.15 mol/L) to the solution.