Composition of essential oils in subterranean organs of three species of Valeriana L

Essential oils from the subterranean organs of three species of Valeriana L. from Iran (Valeriana sisymbriifolia Vahl, Valeriana alliariifolia Adams and Valeriana officinalis L.) belonging to Valerianaceae family have been obtained by hydrodistillation and analysed by gas chromatography-mass spectrometry in order to discern the differences and similarities between the volatile chemical compositions of these species. More than 100 components were identified in essential oils of the studied plants (Supplementary Table S1--online only). The principal common constituents of the three species of Valeriana were spathulenol, limonene, γ-terpinene, vulgarone B and p-cymene. The main essential oil ingredients were α-selinene (7.83%) in V. sisymbriifolia, limonene (3.53%) in V. alliariifolia and spathulenol (13.33%), α-campholenal (11.48%), vulgarone B (8.38%) and valerenal (8.32%) in V. officinalis plants. Ageratochromene (precocene II), a chromene substance with antibacterial, antifungal, insecticidal and antijuvenile hormonal activities, was found at high levels (35.59% and 36.58%) in the essential oils of V. sisymbriifolia plants.     

A microextraction procedure based on a task‐specific ionic liquid for the separation and preconcentration of lead ions from red lipstick and pine leaves

First, the extraction and preconcentration of ultratrace amounts of lead(II) ions was performed using microliter volumes of a task‐specific ionic liquid. The remarkable properties of ionic liquids were added to the advantages of microextraction procedure. The ionic liquid used was trioctylmethylammonium thiosalicylate, which formed a lead thiolate complex due to the chelating effect of the ortho‐positioned carboxylate relative to thiol functionality. So, trioctylmethylammonium thiosalicylate played the roles of both chelating agent and extraction solvent simultaneously. Hence, there is no need to use a ligand. The main parameters affecting the efficiency of the method were investigated and optimized. Under optimized conditions, this approach showed a linear range of 2.0–24.0 ng/mL with a detection limit of 0.0010 ng/mL. The proposed method was applied to the extraction and preconcentration of lead from red lipstick and pine leaves samples prior to electrothermal atomic absorption spectroscopic determination.     

A DFT study on the complexation of La3+ ion with malonamide and diglycolamide ligands

The main goal of this research is to investigate the structural and thermochemical aspects of complexation between La³⁺ with tetrapropyl malonamide (TPMA) and tetrapropyl diglycolamide (TPDGA) ligands via density functional theory (DFT) methods. In this respect, the structural parameters of [La-TPMA]³⁺ and [La-TPDGA]³⁺ complexes have been calculated and compared with the available X-ray crystallographic data. These comparisons revealed that both calculated structural values using B3LYP and M06 are in a reliable agreement with X-ray crystal structure with a near accuracy. In the next step, the more efficiency of diglycolamides in comparison with malonamides in the extraction of La³⁺ have been analyzed by calculating thermochemical properties of the complexation. It should be stated that this issue has been observed in many experimental elucidations. In the next step, the inclusion of solvent effects on thermodynamical properties of complexation has been evaluated via polarized continuum model (PCM) calculations. In this context, enthalpy and Gibbs free energy changes have been determined in the presence of three solvents, chloroform, toluene and n-hexane. Our obtained results demonstrate that using n-hexane as solvent is more favorable thermodynamically than chloroform and toluene that confirms the previously observed experiments. Finally, the bond orders of some selected key bonds in TPMA and TPDGA ligands and their corresponded La³⁺ complexes have been evaluated comparatively to analyze the electronic features of coordination in [La-TPMA]³⁺ and [La-TPDGA]³⁺ complexes.     

Isocyanide‐Based Three‐Component Synthesis of Pyrano‐pyrido‐quinoxalines

Pyrano‐pyrido‐quinoxaline derivatives were synthesized in good yields by a three‐component reaction of isocyanides, dialkyl acetylenedicarboxylates, and pyrido[1,2‐a]quinoxaline‐triones in DMF at 100°.     

Directed Evolution of a Bacterial Laccase (CueO) for Enzymatic Biofuel Cells

Escherichia coli's copper efflux oxidase (CueO) has rarely been employed in the cathodic compartment of enzymatic biofuel cells (EBFCs) due to its low redox potential (0.36 V vs. Ag/AgCl, pH 5.5) towards O₂ reduction. Herein, directed evolution of CueO towards a more positive onset potential was performed in an electrochemical screening system. An improved CueO variant (D439T/L502K) was obtained with a significantly increased onset potential (0.54 V), comparable to that of high‐redox‐potential fungal laccases. Upon coupling with an anodic compartment, the EBFC exhibited an open‐circuit voltage (V_oc) of 0.56 V. Directed enzyme evolution by tailoring enzymes to application conditions in EBFCs has been validated and might, in combination with molecular understanding, enable future breakthroughs in EBFC performance     

Preparation of an efficient catalyst through injection of CuI on modified poly (styrene-co-maleic anhydride) and theoretical investigation of the structural and electronic properties of catalyst

A novel polymer supported [poly (styrene-co-maleic imide) (SMI)]Cu(I) nano-particles was prepared via in situ reaction of 4-amino-5-methyl-4H-1,2,4-triazole-3-thione with [poly (styrene-co-maleic anhydride)] (SMA) along with immobilization of CuI. These nano-particles were fully characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy analysis, Xray (EDAX), inductively coupled plasma (ICP) analysis, ¹H NMR and FT-IR techniques. Moreover, the structural and electronic features of metal–ligand interactions in the complex model of polymer-supported copper nanocatalyst were assessed using density functional theory calculations. The catalytic activity of these supported Cu(I) nonoparticles was examined in one of the classiest name reaction so–called “click reaction” which is coined K. B Sharpless for the regioselective synthesis of 1,2,3-triazole derivatives using a multicomponent reaction (MCR) involving benzyl halides, sodium azide and terminal alkynes in water as a green solvent. This heterogeneous catalyst showed excellent catalytic activity and was separated by simple filtration and was used at least in five consecutive runs without a significant decrease in its activity.     

Viscosity and thermal conductivity of some refrigerants at moderate and high densities on the basis of Rainwater–Friend theory and the corresponding states principle

The initial density dependence of viscosity and thermal conductivity was formulated on the basis of Rainwater–Friend (RF) theory. In this work, we have first focused on the calculation of viscosity and thermal conductivity of moderately dense argon by using RF theory and an accurate ab initio potential function. This theory which was originally presented for spherical potentials have been adapted for calculation of viscosity and translational contribution of thermal conductivity of some refrigerants by introducing the corresponding states correlations for the second transport virial coefficients. Then the internal states contribution for the thermal conductivity has been determined based on the Mason–Monchick and modified Enskog theories. So, we have calculated the viscosity and thermal conductivity of some refrigerants, R32, R14, R12, R13, R22, R134a, R143a, R125, R123, R142b, at moderate densities up to about 2 mol dm⁻³. At high densities, beyond the validity range of RF theory, we have applied correlation expressions for the viscosity and thermal conductivity residual functions to calculate the viscosity and thermal conductivity of supercritical refrigerants and then compared with the available experimental data. In conclusion, we have shown that the RF theory in conjunction with the corresponding states residual functions present the reliable model for calculation of viscosity and thermal conductivity of refrigerants over a comparatively wide temperature and pressure range up to 65 MPa within the experimental errors.     

Nef‐Isocyanide ‐Based One‐pot Two‐step Three Component Dihydrobenzo[4,5]Imidazo[2,1‐b]thiazoles Synthesis

The reactive imidoyl chloride adducts generated in situ from the reaction of isocyanide and acyl chlorides were trapped by 2‐mercaptobenzimidazoles to yield highly functionalized dihydrobenzo[4,5]imidazo[2,1‐b]thiazoles in good yields.     

Evaluation the pozzolanic reactivity of sonochemically fabricated nano natural pozzolan

Natural pozzolans are appropriate supplementary cementitious materials in cement and concrete industry. A simple sonochemical method was developed to synthesize nanostructures of natural pozzolan. Chemical composition, crystallinity, morphology and reactivity of the natural pozzolan samples were compared before and after the sonochemical process, by using powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Thermal Gravimetry and Differential Thermal Analysis (TG/DTA). Compressive strength tests were performed to evaluate the properties of blended cements incorporating nano natural pozzolan. Under optimized conditions, the nano natural pozzolans showed a superior reactivity as compared with the bulk natural pozzolan. Also higher compressive strength was obtained for the cement specimen incorporating nano natural pozzolan.