Rapid probe of the nicotine spectra by high-resolution rotational spectroscopy

Nicotine has been investigated in the gas phase and two conformational forms were characterized through their rotational spectra. Two spectroscopic techniques have been used to obtain the spectra: a new design of broadband Fourier transform microwave (FTMW) spectroscopy with an in-phase/quadrature-phase-modulation passage-acquired-coherence technique (IMPACT) and narrowband FTMW spectroscopy with coaxially oriented beam-resonator arrangement (COBRA). The rotational, centrifugal distortion and hyperfine quadrupole coupling constants of two conformers of nicotine have been determined and found to be in N-methyl trans configurations with the pyridine and pyrrolidine rings perpendicular to one another. The quadrupole hyperfine structure originated by two (14)N nuclei has been completely resolved for both conformers and used for their unambiguous identification.     

Antimycotic effect of the essential oil of Aloysia triphylla against Candida species obtained from human pathologies

The research of alternative substances to treat infections caused by Candida species is a need. Aromatic plants have the ability to produce secondary metabolites, such as essential oils (EO). The antimicrobial properties of Aloysia triphylla (L'Her.) Britton (cedrón) EO has been previously described. The aims of this work were to determine the antimicrobial activity and the effect on the cell structure of the EO of A. triphylla against Candida sp isolated from human illnesses. The EO was obtained by hydrodistillation of A. triphylla leaves. The minimum inhibitory concentration (MIC) was performed with microdilution method and the minimum fungicidal concentration (MFC) was determined. A. triphylla EO's showed antifungal activity against all yeast: C. albicans, C. dubliniensis, C. glabrata, C. krusei, C. guillermondii, C. parapsilosis and C. tropicalis which were resistant to fluconazol (150 mg/mL). The range of MIC values was from: 35 to 140 microg/mL and the MFC: 1842 to 2300 microg/mL. The time of killing at the MFC against C. albicans (3 x 10(5) UFC/mL) was 140 min. The dates of OD620 and OD260 suggest lysis and loss of absorbing material, respectively. The HROM shows distortion in morphology and shape of the cell, with large vacuoles in the cytoplasm. These studies clearly show that A. triphylla EO is a promising alternative for the treatment of candidiasis.     

A note on a question of Dimca and Greuel

In this note, we give a positive answer to a question of Dimca and Greuel about the quotient between the Milnor and Tjurina numbers of an isolated plane curve singularity in the cases of one Puiseux pair and semi-quasi-homogeneous singularities.     

A result on the ideal structure of $$\mathcal L^r(X)$$ L r ( X ) for uniformly convex X

Positivity - We consider the question of when is every positive compact operator, between two given Banach lattices, approximable regular. An immediate consequence of our main result is that,...     

Energy-Conserving Lattice Boltzmann Thermal Model in Two Dimensions

A discrete velocity model is presented for lattice Boltzmann thermal fluid dynamics. This model is implemented and tested in two dimensions with a finite difference scheme. Comparison with analytical solutions shows an excellent agreement even for wide temperature differences. An alternative approximate approach is then presented for traditional lattice transport schemes     

Alkoxide-induced reactions of N-substituted saccharins. Synthesis of 1,2-benzothiazocine 1,1-dioxide and 2,3-dihydropyrrolo[1,2-b]-[1,2]benzisothiazole 5,5-dioxide derivatives

The reactions of saccharin derivatives 1 with sodium alkoxides were studied. Under mild conditions, compounds 1a-f gave the corresponding open sulfonamides 5a-f . Under drastic conditions, β-(saccharin-2)propionic acid derivatives 1a,b reacted with sodium ethoxide affording saccharin and β-ethoxypropionic acid derivatives 4a,b . γ-(Saccharin-2)butyric acid derivatives 1c,d and γ-(saccharin-2)-butyrophenone 1f reacted with sodium t-butoxide in dimethyl sulfoxide affording 5-substituted 6-hydroxy-3,4-dihydro-2H-1,2-benzothiazocine 1,1-dioxides 9 . From mother liquors, 1-substituted 2,3-dihydro-pyrrolo[1,2-b][1,2]benzisothiazole 5,5-dioxides 10 were isolated several hours later, though not detected immediately after completing the reaction. When the reactions were carried out in t-butyl alcohol, the yields of 9 diminished and those of 10 increased with product ratio inversion. Different experimental observations on the possible pathway generating 9 and 10 are discussed.     

1,6‐ and 1,7‐naphthyridines III. 13C‐NMR analysis of some hydroxy derivatives

The ¹³C‐NMR spectra of some 1,6‐naphthyridines 2 and 1,7‐naphthyridines 3 , as well as those of N‐methyl derivatives 4 and 5 , were recorded and analyzed. Results in dimethyl‐d₆ sulfoxide and deuteriochlo‐roform provide useful data on intra and intermolecular hydrogen bonds.     

Solubility of 1,3,5,7-tetra azatricyclo[3.3.1.1]decane (HMT) in water from 275.15 K to 313.15 K

The water solubility of 1,3,5,7-tetra azatricyclo[3.3.1.1^3,7]decane, hexamethylenetetramine (HMT) or urotropine was determined at temperatures between 275.15 K and 313.15 K. Van’t Hoff graphs of ln m_sat versus 1/T gave three different straight lines, suggesting the existence of three different forms of the substance in the temperature region studied.

Previous work reported both increasing and decreasing solubility with temperature. This work found the solubility does not have a simple behavior.     

Voltammetric determination of nitrobenzene with a chemically modified carbon paste electrode. Application to wines, beers and cider

Summary A method for the determination of nitrobenzene with a sepiolite modified carbon paste electrode is presented. Nitrobenzene is adsorbed on the electrode at open circuit (pH 3.5), and determined by differential pulse voltammetry and cyclic voltammetry at pH 5.5 in 0.5 mol/l KNO₃. The calibration is linear up to 0.4 g × ml^–1. The method was applied to the determination of nitrobenzene in wines, beers and cider. The error was ±2% and the standard deviation 5%.

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Voltammetrische Bestimmung von Nitrobenzol mit Hilfe einer chemisch modifizierten Kohlepaste-Elektrode. Anwendung auf Weine, Biere und Apfelwein