Drying dissipative structures of the aqueous solution of sodium <Emphasis Type="Italic">n</Emphasis>-alkyl sulfates on a cover glass

Macroscopic and microscopic dissipative structural patterns formed in the course of drying a series of the anionic detergents, sodium n-alkyl sulfate (n-alkyl = n-hexyl, n-octyl, n-decyl, n-dodecyl, n-hexadecyl, and n-octadecyl), on a cover glass have been observed. The broad ring patterns of the hill accumulated with the detergent molecules are formed around the outside edges in the macroscopic scale. The microscopic patterns of the small blocks, star-like patterns, and branched strings are formed. The pattern area and the time for the dryness have been discussed as a function of detergent concentration and the number of carbons of the detergents. The convection flow of water accompanied by the detergent molecules, change in the contact angles at the drying frontier between the solution and substrate in the course of dryness, and interactions among the detergents and substrate are important for macroscopic pattern formation. Microscopic patterns are determined mainly by the shape and size of molecules, translational Brownian movement of detergent molecules, and the electrostatic and hydrophobic interactions between detergents and/or between the detergent and substrate in the course of solidification.     

Dissipative structures formed in the course of drying an aqueous solution of poly(allylamine hydrochloride) on a cover glass

Macroscopic and microscopic dissipative structural patterns formed in the course of drying a deionized aqueous solution of cationic polyelectrolyte, poly(allylamine hydrochloride) on a cover glass have been observed. Drying times range from 40 min at 45 °C to 450 min at 5 °C, and are insensitive to the polymer concentration. Pattern area shrinks toward the center at the low polymer concentrations, and increases as the concentration increases. A macroscopic broad ring pattern, where the polymer accumulates densely, forms in many cases. Beautiful fractal patterns are observed at the microscopic scale. The fractal dimension increases from 1.2 to 1.6 as polymer concentration increases from 10^-6 monoM to 10^-2 monoM. The relative rates between the water flow at the drying front and the convection flow of water accompanying the movement of polymer are important for the macroscopic and microscopic pattern formation.     

Dissipative structures formed in the course of drying the colloidal crystals of silica spheres on a cover glass

Macroscopic and microscopic dissipative structural patterns formed in the course of drying the deionized aqueous colloidal crystal suspensions of silica spheres (diameter: 103 nm) on a cover glass have been observed. Spoke-like and ring-like patterns are formed in the macroscopic scale; the former is the crack in the sphere film and the latter is the hill accumulated with spheres formed around the outside edge. The neighbored inter-spoke angle, thickness of the film, and other morphological parameters have been discussed as a function of sphere concentration, concentration of sodium chloride, and the inclined angle of the cover glass. Fractal patterns of the mud cracks are observed in the microscopic scale. Capillary forces between spheres at the air-liquid surface and the relative rates between the water flow at the drying front and the convection flow of spheres are important for the pattern formation. Electronic Publication     

The smallest Hosoya index in (<Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">n</Emphasis> + 1)-graphs

A (n, n + 1)-graph G is a connected simple graph with n vertices and n + 1 edges. In this paper, we determine the lower bound for the Hosoya index in (n, n + 1)-graphs in terms of the order n, and characterize the (n, n + 1)-graph with the smallest Hosoya index.     

Drying dissipative structures of aqueous solution of poly (ethylene glycol) on a cover glass

Macroscopic and microscopic dissipative structural patterns formed in the course of drying a series of poly (ethylene glycol) (PEG) having molecular weights ranging from 1,000 to 2×10⁶ in aqueous solution have been studied on a cover glass. The broad ring patterns of the hill accumulated with the polymers are formed irrespective of the molecular weights of PEG molecules. The single round hills are formed also in the center in the macroscopic scale, when the molecular weight is large. The characteristic convection flow of the polymers and the interactions among the polymers and substrate are important for the macroscopic pattern formation. Cross-like fractal patterns are observed, especially for the diluted solutions in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the polymers and/or between the polymer and the substrate in the course of solidification. Interestingly, these microscopic patterns are reflected based on the shape and size of the PEG polymers.     

<Emphasis Type="Italic">Ab initio</Emphasis> investigation of aniline and <Emphasis Type="Italic">n</Emphasis>-propylamine associates with dimethylsulfoxide,isobutyronitrile, and N-methylpiperidone

The structure of the dimer associates of aniline and n-propylamine with dimethylsulfoxide, isobutyronitrile, and N-methylpiperidone was investigated by ab initio calculations. Stable configurations of the complexes and their structural and energy characteristics have been determined. The effects of the nature of the solvent and the structure of the associate on the properties of the NH₂ group are examined.     

Mechanistic studies on particle nucleation in the batch emulsion polymerisation of<Emphasis Type="Italic"> n</Emphasis>-butyl acrylate containing multifunctional monomers

This paper reports the mechanistic details concerning the synthesis of crosslinked poly(n-butyl acrylate) dispersions intended to be used as seeds in the preparation of core-shell emulsions. The influence of crosslinking comonomers and the amount and type of surfactants on the kinetics, particle nucleation, particle size and particle size distribution in the batch emulsion polymerisation of n-butyl acrylate (BA) is explored. In the case of EGDA (ethylene glycol diacrylate) crosslinker the particle number decreased with increasing crosslink density, whereas the opposite trend was observed in the case of m-diisopropenylbenzene (m-DIPB) in the presence and absence of the surfactant sodium dodecyl sulfate (SDS). The observed behaviour is mainly attributed to the variation in the aqueous phase kinetics caused by the water solubility of the comonomer, which influences the formation rate of precursor particles during the nucleation stage. Only for the less water soluble crosslinker, DIPB, could the increase of particle number be explained within the Smith–Ewart theory by assuming prolonged nucleation due to reduced swelling of growing particles with monomer as a result of the crosslinking reaction.Abbreviations EGDA ethylene glycol diacrylate - m-DIPB meta-diisopropenylbenzene - SDS sodium dodecyl sulfate - PBA poly(n-butyl acrylate) - AFFF asymmetric field flow fractionation - MALLS multiangle laser light scattering - CMC critical micelle concentration     

Skeletal Isomerization of <Emphasis Type="Italic">n</Emphasis>-butenes over Solid Acid Catalysts

Conversion reactions of n-butenes over zeolites and amorphous catalysts have been investigated to deduce the factor that determines the selectivity for the skeletal isomerization producing isobutene. The effects of pore structure and acid site concentration on the selectivity for the skeletal isomerization are discussed on various catalysts. The pore structures of FER and CLI zeolites induce the distant locations of butene molecules, accelerating monomolecular skeletal isomerization. On the other hand, acid site concentration determines the preferred reaction path of n-butenes on amorphous catalysts. Oligomerization followed by cracking that produces various hydrocarbons is suppressed on the catalyst with low acid site concentration, resulting in high selectivity for isobutene. The feasibility of monomolecular skeletal isomerization on zeolites and amorphous catalysts is confirmed by its reversibility with high selectivity.     

A new stilbene glycoside from the <Emphasis Type="Italic">n</Emphasis>-butanol fraction of <Emphasis Type="Italic">Veratrum dahuricum</Emphasis>

A new stilbene glycoside, 5-methylresveratrol-3,4′-O-β-D-diglucopyranoside (1), was isolated from the n-butanol fraction of the rhizomes of Veratrum dahuricum, together with five known stilbenoids: resveratrol-3-O-β-D-glycoside (2), 4′-methylresveratrol-3-O-β-D-glycoside (3), oxyresveratrol-4′-O-β-D-glycoside (4), oxyresveratrol-3-O-β-D-glycoside (5), and oxyresveratrol-3,4′-O-β-D-diglycoside (6), and found for the first time in the investigated plant. The structures of six isolates were identified on the basis of 1D and 2D NMR data. Compounds 1–6 showed platelet aggregation inhibition, and compound 1 had an IC₅₀ value of 383.6 μM against platelet aggregation induced by AA. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 279–282, May–June, 2009.     

New flavonoid-<Emphasis Type="Italic">C</Emphasis>-glycosides from <Emphasis Type="Italic">Triticum aestivum</Emphasis>

Two new flavonoid-C-glycosides named triticuside A (1a) and triticuside B (1b) were isolated from bran of Triticum aestivum L. The structures of the two new compounds were elucidated by spectral techniques including ¹H NMR, ¹³C NMR as well as HSQC, HMBC, and COSY. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 135–137, March–April, 2008.     

Layered Crystalline Barium Phenylphosphonate as Host Support for <Emphasis Type="Italic">n</Emphasis>-Alkylmonoamine Intercalation

Layered barium phosphonate, synthesized by combining the metallic salt with a phenylphosphonic acid solution, yielded Ba(HO₃PC₆H₅)₂ ·H₂O (BaPP), which gives the corresponding anhydrous compound on heating. n-Alkylmonoamines intercalation into the crystalline lamellar precursor resulted in compounds having the general formula Ba(HO₃PC₆H₅)₂ ·xH₂N(CH₂) _n CH₃ ·(1−x)H₂O (n=1–5). The intense infrared bands in the 1160–695 cm⁻¹ interval confirmed the presence of the phosphonate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns for both hydrated and anhydrous compounds. The thermogravimetric curves for both supports showed the release of water molecules and the organic moiety in distinct stages to yield a final Ba(PO₃)₂residue. An additional amine mass loss steps was observed for the corresponding aminated compounds. One isolated DSC peak found in the layered precursor compound contrasts by its absence in the anhydrous form and the ³P NMR spectrum presented one peak for attached phenylphosphonate groups centered at 12.4 ppm. An increase in carbon and hydrogen percentages for intercalated compounds followed the amine size chain with a corresponding decrease in nitrogen percentage. The interlayer distance (d) correlates linearly with the number of carbon atoms (n _c ) of the alkylamine chains, d=1467 + 62n _c and d=1688 + 60n _c , for the hydrated and anhydrous compounds, respectively, permitting inference of the interlayer distance for an unknown amine.This revised version was published online in July 2005 with a corrected issue number.     

Synthesis of 6-methyl-8<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">a</Emphasis>,<Emphasis Type="Italic">g</Emphasis>]quinolizin-8-imines <Emphasis Type="Italic">via Reissert</Emphasis> compounds

Alkylation of Reissert compounds derived from 3-methylisoquinolines with several 2-cyanobenzylbromides followed by hydrolytic cleavage provided the corresponding 1-benzyl-3-methylisoquinolines. Treatment of the latter with methylmagnesiumiodide caused cyclization to the title compounds rather than formation of 2-acetylbenzylisoquinolines.     

Drying dissipative structures of the aqueous suspensions of monodisperse bentonite particles

Macroscopic and microscopic dissipative structural patterns formed in the course of drying the fractionated and monodisperse bentonite particles (plate-like in their shape) in aqueous deionized suspension and in the presence of NaCl have been studied on a cover glass. The patterns coexisted with the broad ring of the hill accumulated with the particles and with the round hills are formed around the outside edges of the film and in the center, respectively, in the macroscopic scale. By the addition of NaCl the pattern shifts from the broad ring to the round hill in the center. The spoke-like cracks, which have been observed for the suspensions of the spherical particles so often hitherto, are not observed at all for the bentonite suspensions. The characteristic convection flow of the particles and the interactions among the particles and substrate are important for the macroscopic pattern formation. Wrinkled, branch-like and/or star-like fractal patterns are observed in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the particles and/or between the particle and the substrate in the course of drying.     

Adsorption of<Emphasis Type="Italic"> N</Emphasis>-dodecyl-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-3-ammonio-1-propanesulfonate (DDAPS), a model zwitterionic surfactant,on the Au(111) electrode surface

Electrochemical measurements including cyclic voltammetry, differential capacity, and chronocoulometry have been used to characterize the adsorption behaviors of the zwitterionic surfactant N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS) on the Au(111) electrode surface. The thermodynamics of the ideally polarized electrode have been employed to determine the Gibbs excess and the Gibbs energy of adsorption. The results show that the adsorption of DDAPS has a multistate character. The first two states are observed at potentials close to zero charge. At low bulk DDAPS concentrations, it corresponds to the formation of a film of nearly flat adsorbed molecules. At higher concentrations it is converted into a hemimicellar state. The second state is formed at negative potentials and charge densities close to 0 C cm^–2. It corresponds to a film of tilted molecules oriented with the hydrocarbon tail towards the metal and the polar head toward the solution.Dedicated to Professor Zbigniew Galus on the occasion of his 70^th birthday and in recognition of his many contributions to electrochemistry.     

Lipids from <Emphasis Type="Italic">Halostachys caspica</Emphasis> and <Emphasis Type="Italic">Halocharis hispida</Emphasis>

The composition of lipids from the aerial parts of two species of halophytes from the family Chenopodiaceae, Halostachys caspica C. A. Mey. and Halocharis hispida Bge. was determined. Neutral lipids (NL, 62.1 and 54.2%, respectively) dominated the total lipids (TL) of these plants. More than a third of the NL were esters of aliphatic alcohols and phytosterols (FAE). Fatty acids 16:0, 18:1, and 18:2 dominated the acids of FAE; 16:0, 18:1, and 18:3, the phospholipids. The principal fatty acids of glycolipids were unsaturated acids (68.3 and 75.1%) with linolenic acid dominating (44.9 and 43.5%). Presented at the 7th International Symposium on the Chemistry of Natural Compounds, Tashkent, October 16–18, 2007. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 276–278, May–June, 2009.     

Antioxidant flavonoids from <Emphasis Type="Italic">Tamus communis</Emphasis> ssp. <Emphasis Type="Italic">cretica</Emphasis>

A new flavonoid, kaempferol-3,4′-di-O-α-L-rhamnopyranoside (1), and three known flavonoids (2–4) were isolated from the aerial parts of T. communis L. The structure of the new compound was elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed significant antioxidant activity (IC₅₀ 187.151 ± 0.821 μM, and 92.079±0.513 μM, respectively), whereas compounds 3 and 4 showed moderate activity in DPPH free radical scavenging assays. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 295–297, May–June, 2009.     

Rapid molecular typing of <Emphasis Type="Italic">Tuber melanosporum</Emphasis>, <Emphasis Type="Italic">T. brumale</Emphasis> and <Emphasis Type="Italic">T. indicum</Emphasis> from tree seedlings and canned truffles

We have developed new DNA extraction and purification procedures for investigation of mycorrhized seedlings and canned truffles. Use of these procedures on approximately 100 mg initial material enabled good sample representation. For mycorrhized seedlings, Taq polymerase inhibitors were discarded irrespective of tree species. In routine analysis we systematically used consensus primers ITS1/ITS4 to check the absence of Taq polymerase inhibitors and the presence of fungus DNA. Positive response with ITS validates other positive or negative PCR results. Absence of amplification with ITS prevents validation of other results. For canned truffles, DNA harvested from ascocarps sterilized for one and a half hours at 115°C was amplified with specific primers. We have developed consensus primers, named R12/F12, to check for the presence of amplifiable fungus DNA and the absence of Taq polymerase inhibitors. Here also, positive response with consensus R12/F12 validates other positive or negative PCR results. We have developed one primer pair specific for T. brumale and another specific for T. melanosporum. We can then characterize these two taxa, which enables the use of truffle or truffled French designations. We can also characterize T. indicum, the Asiatic black truffle that might fraudulently be sold as T. melanosporum and T. brumale. These three specific primer pairs were used independently of DNA extraction from tree seedlings or canned truffles. Our process is specific, sensitive, convenient, and quick.J.P. Douet and D. Mabru have contributed equally to this work     

The costly process of creating a cavity in <Emphasis Type="Italic">n</Emphasis>-octanol

Free-energy perturbation calculations are used to evaluate the free energy of cavity formation in n-octanol. A detailed theoretical analysis of the procedure is given and some limiting value phenomena are discussed. The data become subject to a three-parameter fit and a revised formulation of the popular approach due to Pierotti of calculating cavitation free energies is given. Pierottis approach is based on the equation derived from scaled particle theory (SPT) by Reiss et al. [(2000) J. Chem. Phys. 31:369–380]. The revision of Pierottis approach has the important advantage of being completely independent of the solvent hard-sphere radius, an empirical parameter in the standard procedure, which is hard to define in a uniformly valid way.Acknowledgments. S.H. gratefully acknowledges supercomputing support from the University of Linz, GUP, Professor Volkert and Dr. Kranzlmüller, and the University of Salzburg, RIST⁺⁺, Professor Zinterhof.Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail     

Excess Volumetric and Spectroscopic Properties of Mixtures of Some <Emphasis Type="Italic">n</Emphasis>-Alkoxyethanols and of Some Polyethers with 2-Pyrrolidinone and <Emphasis Type="Italic">N</Emphasis>-Methyl-2-Pyrrolidinone at 298.15 K

Excess molar volumes V_m^E for binary liquid mixtures of n-alkoxyethanols or polyethers + 2-pyrrolidinone or N-methyl-2-pyrrolidinone have been measured with a continuous dilution dilatometer at 298.15 K and atmospheric pressure as a function of composition. The alkoxyethanols are diethylene glycol monomethylether, 2-(2-methoxyethoxy) ethanol, CH₃(OC₂H₄)₂OH; diethylene glycol monoethylether, 2-(2-ethoxyethoxy) ethanol, C₂H₅(OC₂H₄)₂OH; and diethylene glycol monobutylether, 2-(2-butoxyethoxy) ethanol, C₄H₉(OC₂H₄)₂OH; whereas the polyethers are diethylene glycol dimethylether, bis(2-methoxyethyl)ether, CH₃(OC₂H₄)₂OCH₃; diethylene glycol diethylether, bis(2-ethoxyethyl)ether, C₂H₅(OC₂H₄)₂OC₂H₅; and diethylene glycol dibutylether, bis(2-butoxyethyl)ether, C₄H₉(OC₂H₄)₂OC₄H₉. In all mixtures the excess molar volumes are negative and symmetric across the entire composition range. The excess volumes are fitted to the Redlich–Kister polynomial equation to obtain the binary coefficients and the standard errors. The experimental results have also been discussed on the basis of IR measurements.     

Quantum chemical investigation of structural and thermodynamic peculiarities of the formation of cucurbit[<Emphasis Type="Italic">n</Emphasis>]urils

Calculations of the structures of cucurbit[n]urils (n = 5–8) and estimations of thermodynamic parameters of their formation are carried out using a high-performance program package PRIRODA at the density functional theory level using the PBE functional and DZ basis set optimized for this functional. Based on the calculated Gibbs free energies of the reaction of CB[n] formation, it is concluded that the CB[6] homolog slightly dominates among the other products of the synthesis.