The Hausdorff dimension of the Smale-Williams solenoid with different contraction coefficients

In this paper we prove that the Hausdorff dimension of the Smale-Williams solenoid with different contraction coefficients is given by the formula . Further, for we prove that the Hausdorff dimension of each angular section is equal to .

     

Atmospheric pressure chemical ionization mass spectrometry of aldehydes in biological matrices

Application of high-performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) for detection of aldehydes in biological samples such as blood, yoghurt, and milk, is reported. Sample preparation is easy, and the presented method is both sensitive and selective. It is based on the widely used dinitrophenylhydrazine derivatization, followed by extraction with n-hexane and a simple reversed-phase HPLC separation. Detection is performed by atmospheric pressure chemical ionization (APCI) in negative ion mode, with detection limits in the low picogram range. Using MS/MS, acetone and propionaldehyde can clearly be distinguished, facilitating propionaldehyde quantitation even in the presence of high acetone levels. Quantitation by direct MS/MS is also feasible, well suited for high-throughput applications, although not as accurate as using HPLC/MS/MS.     

Principal component analysis of polymer–solvent and filler–solvent interactions by inverse gas chromatography

Polymers (polyethylene, polyurethane), silica and modified silicas (modified with: N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-merkaptopropyltrimethoxysilane, triethoxyoctylsilane) were examined by inverse gas chromatography at four different temperatures: 363, 383, 393 and 403 K. The modifiers of silica were applied at five different concentrations. Small amounts of the following test solutes were injected to achieve the infinite dilution conditions: pentane, hexane, heptane, octane, nonane, dichloromethane, chloroform, carbon tetrachloride, and 1,2-dichloroethane.

The retention times for these test solutes were determined and Flory–Huggins parameters were calculated. Values of these physico-chemical parameters characterizing the examined materials were arranged in a matrix form: in the rows the supports and modifiers were enumerated at different temperatures whereas the columns contained the test solutes. The input matrix was subject to principal component analysis after standardization. Three principal components explain more than 93% of the total variance in the data. Four test solutes (hexane, heptane, chloroform and carbon tetrachloride) carry very similar information. Therefore, it is justified to eliminate any three of them from the series of test solutes. Modifiers, supports and various temperatures were classified and different groups were observed according to the dominant interactions. Type of modifier, its content, and temperature can change and shift the properties from the dominant clusters to the neighboring clusters. Unambiguous separation was observed in cases of silica modified with 5 and 10 parts of triethoxyoctylsilane at all examined temperatures.     

C19 and C20 Diterpene Alkaloids from Aconitum toxicum Rchb.

Acotoxinine ( 1 ), a new norditerpene alkaloid, was isolated from the roots of Aconitum toxicum Rchb ., together with the structurally related C₁₉ diterpene alkaloids neoline ( 2 ) and aconitine ( 3 ) and C₂₀ diterpene alkaloids songorine ( 4 ) and songoramine ( 5 ). The structures were elucidated by HR‐MS and advanced NMR methods, including ¹H‐NMR, JMOD, ¹H,¹H‐COSY, HSQC, and HMBC experiments. This is the first report of C₂₀ diterpenoid alkaloids in Aconitum toxicum.     

PHYCOERYTHROCYANIN: ITS SPECTROSCOPIC BEHAVIOR AND PROPERTIES

Abstract— Phycoerythrocyanin is a biliprotein found in very few blue-green algae. Its properties have been examined under three conditions: in whole cells, in light-harvesting organelles (the phycobilisomes). and as an isolated protein. Absorption and fluorescence bands characteristic of the isolated protein are essentially the same as those in intact cells of the blue-green alga Anabaena variabilis. The same spectroscopic hallmarks are observed in purified phycobilisomes. Dissociation of these physobilisomes at low-phosphate concentrations resulted in increased phycoerythrocyanin fluorescence. This time-dependent increase in fluorescence demonstrates the function of this biliprotein in excitation-energy transfer to the other biliproteins when the organelles are intact. The relative stabilities of the various heteroprotein bonds within the phycobilisomes are shown to possess differing phosphate ion dependencies. Studies on the isolated protein from Mastigocladus laminosus include fluorescence measurements at both 23 and-196°C, as is generally observed with biliproteins, although phycoerythrocyanin has complex visible absorption and excitation spectra, only a single emission band is observed.     

Calculation of the kinetic energy release of charge separation processes

Kinetic energy release (KER) was studied by experimental methods and semiempirical (MNDO and AM1) molecular orbital calculations in the case of various charge separation processes: loss of a methyl ion from [CH₃? C₄? CH₃]²⁺, [CH₃? C₃? CH₃]²⁺ and [N,N-dimethyl-p-phenylenediamine]²⁺. It was found that the KER corresponding to the width of a dish-topped peak at half-height is very close to the mean KER of the process. The calculated potential energy curves of these reactions show significant reverse critical energies, a large part of which was found to be due, in agreement with conventional assumptions, to electric repulsion between the two separating singly charged products. The bond order between the two separating ions is nearly zero in the transition state, so exchange of internal energy between them is unlikely. These explain the good agreement between the (calculated) reverse critical energy and the measured kinetic energy release.     

Molecular Structure of 1,2,4,5-Tetracyanobenzene from Gas-Phase Electron Diffraction and Theoretical Calculations

The molecular structure of 1,2,4,5-tetracyanobenzene has been determined by gas-phase electron diffraction and by ab initio calculations at several levels of theory. The electron diffraction study indicates an elongation of the aromatic ring along the (H)CC(H) axis, characterized by angular deformation of the benzene ring and lengthening of the (NC)C—C(CN) bonds. The following bond lengths (r _g) and bond angles were obtained by electron diffraction: .     

Amino acid cluster formation studied by electrospray ionization mass spectrometry

The association properties of natural and non-natural amino acids were studied in detail using electrospray ionization mass spectrometry. The results show a highly diverse cluster formation behavior of amino acids. There are differences regarding the degree of clustering (average cluster size), the presence or absence of one or several 'magic' clusters of special stability and the influence of chirality on cluster stability. Cluster formation does not show a good correlation with simple physico-chemical properties (such as solubility), indicating that it is a specific process and not only a simple aggregation during evaporation/ionization. A systematic study of cluster formation of serine derivatives reveals that all functional groups play a prominent role in the binding of the magic octamer. The results support the idea of the zwitterionic character of the octamer. Electrospray ionization of the side-chain acetylated serine shows the formation of a very stable tetramer with a strong preference for homochirality. The results suggest that Ser8 is made up of two tetramer subunits, held together by hydrogen bonds of the side-chain.     

Solvation enthalpies and heat capacities of n-alkanes in four polymer phases by capillary gas chromatography

Molar solvation enthalpy (deltasol H(o)298) and molar heat capacity changes (deltasol C(o)p) were determined by gas chromatography for the C6-C12 n-alkanes on four preferred stationary phases (100% polydimethyl siloxane, 50% diphenyl-50% dimethyl polysiloxane, 50% trifluoropropyl methylsiloxane, and polyethylene glycol) in commercial FSOT. Statistical evaluation indicated the temperature independence of deltasol C(o)p in the range 303-393 K. Deltasol H(o)298 depends linearly on the number of carbon atoms in the n-alkanes, but no linearity could be established for deltasol C(o)p of higher homologues on polar columns, which may be due to a more ordered state on the liquid phase. The homologues for which a linear temperature dependence exists demonstrated that deltasol C(o)p is related linearly to the van der Waals volume and the temperature derivative of the density of the stationary phase. The results are consistent with a simple physical explanation at the molecular level.     

Phosphorylated Acid Anilides as New Insecticides

Abstract

Some new phosphorodithioates containing acid anilide-group have been synthesized and the relationship between insecticidal activity and the structure of the compounds has been studied.