Chemical composition and antimicrobial activity of the essential oils of Ferula latisecta and Mozaffariania insignis from Iran

The hydrodistilled oils from the aerial parts of Ferula latisecta and Mozaffariania insignis, which is endemic to Iran, were analyzed by GC and GC/MS. (Z)-Ocimenone (32.4%), (E)-ocimenone (20.3%), and cis-pinocarvone (11.4%) were the main components among the 22 constituents characterized in the oil of F. latisecta, representing 87.7% of the total components detected. Twenty-five compounds were identified in the oil of M. insignis, representing 99.0% of the total oil, with octyl acetate (41.1%), β-pinene (30.3%), and α-pinene (23.9%) as the main constituents. The essential oils were examined for their potential antimicrobial activities. Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 561–563, November–December, 2006.     

New synthesis of nanopowders of proton conducting materials. A route to densified proton ceramics

Low temperature routes have been developed for the preparation of BaCe_0.9Y_0.1O_2.95 (BCY10) and BaZr_0.9Y_0.1O_2.95 (BZY10) in the form of nanoparticulate powders for use after densification as ceramic membranes for a proton ceramic fuel cell. These methods make use on the one hand of the chelation of metal (II), (III) and (IV) ions by acrylates (hydrogelation route) and on the other of the destabilisation and precipitation of micro-emulsions. Both routes lead to single phase yttrium doped barium cerate or zirconate perovskites, as observed by X-ray diffraction, after thermal treatment at 900 °C for 4 h for BCY10 and 800 °C for BZY10. These temperatures, lower than those usually used for preparation of barium cerate or zirconate, lead to oxide nanoparticles of size <40 nm. Dense ceramics (?95%) are obtained by sintering BCY10 pellets at 1350 °C and BZY10 pellets at 1500 °C for 10 h. The water uptake of compacted samples at 500 °C is 0.14 wt% for BCY10 and 0.26 wt% for BZY10. Total conductivities in the range 300-600 °C were determined using impedance spectroscopy in a humidified nitrogen atmosphere. The total conductivity was 1.8×10⁻² S/cm for BCY10 and 2×10⁻³ S/cm for BZY10 at 600 °C. The smallest perovskite nanoparticles and highest conductivities were obtained by hydrogelation of precursor barium, zirconium, cerium and yttrium acrylates.     

Efficient diastereo- and enantioselective synthesis of α,β-disubstituted γ-phosphono sulfonates

The first asymmetric synthesis of α,β-disubstituted γ-phosphono sulfonates is reported. The key step is the Michael addition of a lithiated enantiopure sulfonate bearing an inexpensive chiral sugar auxiliary to α,β-unsaturated phosphonates in good diastereoselectivities. After chromatographic purification, the cleavage of the chiral sugar auxiliary proceeds without any epimerization or racemization to form the corresponding isopropyl sulfonate in very good overall yield (75%) and excellent diastereomeric and enantiomeric excess (de, ee ? 95%).     

Synthesis of Novel Polycyclic Indole‐Annulated Thiopyranocoumarin Derivatives via Domino Knoevenagel–Hetero‐Diels–Alder Reaction in Aqueous Media

An efficient synthesis of polycyclic indole derivatives is achieved via domino Knoevenagel–hetero‐Diels–Alder reaction of O‐acrylated salicylaldehyde derivatives with dihydroindole‐2‐thiones in H₂O as solvent. The products are formed in good‐to‐excellent yields with high regio‐ and stereoselectivity.     

A new and convenient approach to heterotetracyclic benzoxazocines through addition of 1,3-dicarbonyl compounds to quinolinium salts

The synthesis of a series of benzoxazocines has been achieved in good yields by tandem C-alkylation and intramolecular O-alkylation of 1,3-dicarbonyl compounds with quinolinium salts. This is a novel example of the synthesis of eight-membered rings via a tandem process, which provides a method for the synthesis of medium-ring heterocycles.     

Synthesis and application of a novel solid-phase microextraction adsorbent: hollow fiber supported carbon nanotube reinforced sol-gel for determination of phenobarbital

The present study reports the development, validation and application of a new green liquid chromatographic method for the determination of glutathione (GSH) in vegetable samples. In this work we introduce—for the first time—ethyl propiolate (EP) as an advantageous post-column derivatization reagent for thiolic compounds. GSH (t_R = 6.60 min) and N-acetylcysteine (NAC, internal standard) (t_R = 11.80 min) were separated efficiently from matrix endogenous compounds by using a 100% aqueous mobile phase (0.1%, v/v CH₃COOH in 1 mmol L⁻¹ EDTA, Q_V = 0.5 mL min⁻¹) and a Prevail^® reversed phase column that offers the advantage of stable packing material in aqueous mobile phases. The parameters of the post-column reaction (pH, amount concentration of the reagent, flow rates, length of the reaction coil and temperature) were studied. The linear determination range for GSH was 1–200 μmol L⁻¹ and the LOD was 0.1 μmol L⁻¹ (S/N = 3). Total endogenous GSH was determined in broccoli, potato, asparagus and Brussels sprouts using the standards addition approach. The accuracy was evaluated by both recovery experiments (R = 91–110%) and comparison to an o-phthalaldehyde/glycine corroborative post-column derivatization fluorimetric method.     

Comprehensive DFT calculations on organic sulfuric acid derivatives to design of powerful neutral organic superacids

In order to examine the acidity of organic sulfuric acid derivatives in gas phase, comprehensive density functional theory (DFT) calculations at B3LYP/6-31++G(d,p) level have been undertaken. In the title compounds, one of the oxygen atoms is substituted by an 1,3-cyclopentadiene group. The focus of this paper is on DFT studies of two classes of sulfuric acid derivatives: dithionic and peroxydisulfuric acids. Tautomers of proposed organic sulfuric acids are also investigated. DFT calculations indicate that the acidity of the proposed acids without any electron withdrawing groups on the ring was more than sulfuric acid.

     

Numerical solution of nonlinear Jaulent–Miodek and Whitham–Broer–Kaup equations

In this work we investigate the numerical solution of Jaulent–Miodek (JM) and Whitham–Broer–Kaup (WBK) equations. The proposed numerical schemes are based on the fourth-order time-stepping schemes in combination with discrete Fourier transform. We discretize the original partial differential equations (PDEs) with discrete Fourier transform in space and obtain a system of ordinary differential equations (ODEs) in Fourier space which will be solved with fourth order time-stepping methods. After transforming the equations to a system of ODEs, the linear operator in JM equation is diagonal but in WBK equation is not diagonal. However for WBK equation we can also implement the methods such as diagonal case which reduces the CPU time. Comparing numerical solutions with analytical solutions demonstrates that those methods are accurate and readily implemented.     

The effect of solid adsorbents in Triethanolamine (TEA) solution for enhanced CO2 absorption rate

This study aimed to investigate CO₂ absorption using chemical solvent of amine H₂O-TEA-CO₂ in presence of activated carbon (AC) particles. The studied experimental range includes the temperature in range of 293–333 K, pressure in range of 3.5–9.5 bar, the concentration of solvents in range of 2.5–8.5 wt%, and amount of activated carbon in range of 0.3–0.9 kg/m³. The central composite design (CCD) with four parameters of temperature, pressure, amine concentration, and active carbon was applied in 5 levels. The physical solubility CO₂ in amine solutions decreases with the increasing temperature that indicates the process is exothermic. The optimal values of temperature, pressure, concentration, and active carbon are 303.0 K, 8.00 bar, 7.00 M, 0.75 g, respectively, and 25.99% for the input variables and desirability index of 0.732. The CO₂ loading, absorption capacity, and absorption percentage are obtained in the range of 0.572–1.180 mol_CO2/mol_TEA, 0.208–0.506 wt%, and 12.73–32.61% in Triethanolamine (TEA) solutions in activated carbon, respectively. All dependent variables had a p value of less than 0.05, indicating that models were significant and substantial. The result showed that the addition of solid particles to chemical solvents effectively enhances CO₂ absorption.