Use of binomial coefficients in fast and accurate calculation of Löwdin-<Emphasis Type="Italic">α</Emphasis> radial functions

In the present paper, we introduce a new algorithm for the development of efficient numerical methods for the analytical solution of the Löwdin-α radial function. The final results are expressed through the binomial coefficients, which enable fast and accurate calculation of the Löwdin-α radial function. The comparisons of the obtained results with the literature have shown that the presented approach can be used for the fast calculation of multicenter multielectron integrals over Slater-type orbitals (STOs). The efficiency of the algorithm is discussed and its performance with several examples is demonstrated.     

Standard thermodynamic functions and constants of the formation of Nd<Superscript>3+</Superscript> and Lа<Superscript>3+</Superscript> complexes with glycine in aqueous solutions at 298 K

The enthalpies of complexation of glycine (HGly^±) with Nd³⁺ and La³⁺ ions at 298.15 K and at an ionic strength of 0.5 (KNO3) are determined by means of calorimetry. The thermodynamic characteristics of the reactions of formation are calculated for NdGly²⁺, NdGly ₂ ⁺ , LaGly²⁺, and LaGly ₂ ⁺ complexes.     

Lι, Lα, Lβ and Lγ X-ray fluorescence cross-sections of heavy elements for the exciting photons energy 38.18, 43.95, 50.21 and 59.5 keV

The cross-sections for the production of L_ι, L_α, L_β and L_γ X-ray fluorescence (XRF) in Er, Ta, W, Au, Hg, Tl, Pb and Bi by photons with energies in the range 38–59.5 keV have been measured, using a standard doublereflection experimental set-up. Measurements have been performed using an annular 241 Am primary source and X-ray emitting secondary-exciter system. Experimental cross-sections have been compared with the theoretically calculated values of L X-ray cross-sections and fairly good agreement is observed between the experimental and theoretical values.     

Thermodynamic analysis of the structure of aqueous solutions of C<Subscript>12</Subscript>–C<Subscript>18</Subscript> hydrocarbons

Thermodynamic cycles including the increments \(\Delta G_{CH_2 }^0 , \Delta H_{CH_2 }^0 \), and \(T\Delta S_{CH_2 }^0 \) were constructed for dissolution, evaporation, hydrophobic hydration of C₅–C₉ hydrocarbons, and transfer from vapor (\(\Delta G_{CH_2 }^0 \) = ?0.7 kJ·mol^?1, \(\Delta H_{CH_2 }^0 \) = 2.9 kJ·mol^?1, \(T\Delta S_{CH_2 }^0 \) = 3.6 kJ·mol^?1) and water (\(\Delta G_{CH_2 }^0 \) = ?1.4 kJ·mol^?1, \(\Delta H_{CH_2 }^0 \) = 5.8 kJ·mol^?1, \(T\Delta S_{CH_2 }^0 \) = 7.2 kJ·mol^?1) to micelles of C₁₂–C₁₈ hydrocarbons. The formation of bistable hydrated micelles of C₁₂–C₁₈ is explained by a transition between the order-disorder states in an assembly of small (nano) systems of water. The extensive parameters of small systems and critical phenomena predicted by fluctuation theory are discussed.     

Determination of ecdysteroids in <Emphasis Type="Italic">Fornicium unflorum</Emphasis> (L.) and <Emphasis Type="Italic">Serratula centauroides</Emphasis> (L.) raw materials by chromatography–UV spectrophotometry

A chromatography–spectrophotometry method is developed for determining total ecdysteroids in terms of 20-hydroxyecdysone in Serratula centauroides (L.) and Fornicium unflorum (L.) raw materials, based on the purification of extracts from the plant raw materials with aluminum oxide and subsequent spectrophotometric determination relative to a 20-hydroxyecdysone reference sample. Ecdysteroids were determined in plants by HPLC; rhapontisterone and turkesterone are found in F. uniflorum for the first time.     

Synthesis and examination of antimicrobial properties of aminomethylated derivatives C<Subscript>6</Subscript>–C<Subscript>7</Subscript> of alicyclic diols

Synthesis of C₆–C₇ alicyclic diols was studied by a catalytic oxidation of cyclohexene, norbornene and their methyl derivatives in the presence of heterogenized molybdenum-containing catalysts. By a triple condensation of the diols with formaldehyde and secondary amines a synthesis of their aminomethylated derivatives with various substituents at nitrogen atom was examined. Antimicrobial properties of the synthesized amino alcohols in M-10 oil as additives with fungicidal and bactericidal activities were studied.     

Enthalpy of solution of VOCl<Subscript>3</Subscript> in dilute sodium hydroxide solutions and the standard enthalpy of formation of the HVO<Stack><Subscript>4</Subscript><Superscript>2−</Superscript></Stack> ion

The calorimetric enthalpies of solution of liquid vanadium oxytrichloride in dilute sodium hydroxide solutions were measured at 298.15 K and ionic strengths I = 0.5, 1.0, or 1.5 (NaClO₄). The standard enthalpy of formation of the HVO ₄ ^2? ion was calculated from the measured data.     

Synthesis of L‐6‐Chloropyrroloindoline of Chloptosin Cyclohexapeptide

Abstract

Chloptosin is an apoptosis‐inducing dimeric cyclohexapeptide. Enantioselective synthesis of L‐6‐chloropyrroloindoline, as the key chiral synthon of the cyclohexapeptide of chloptosin, was successfully achieved starting from 3‐chloroaniline by utilizing Fischer indole/Schöllkopf protocol and oxidative cyclization of resulting L‐6‐chlorotryptophan.     

Regime of superhigh reactivity of the YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>6 + δ</Subscript> superconductor toward the components of air

Physicochemical features of the YBa₂Cu₃O_{6 + δ} superconductor synthesized via ceramic route and subjected to a kind of modification by long-term exposure to an atmosphere with low pH₂O have been studied by X-ray diffraction, thermal analysis, and magnetometry. The resulting material had a high degree of saturation with air components at room temperature and 30% humidity, up to 1.5 wt % in 30 days, which is not inherent in YBa₂Cu₃O_{6 + δ}.     

Plantlet Regeneration from Callus Cultures of Selected Genotype of <Emphasis Type="Italic">Aloe vera</Emphasis> L.—An Ancient Plant for Modern Herbal Industries

Aloe vera L., a member of Liliaceae, is a medicinal plant and has a number of curative properties. We describe here the development of tissue culture method for high-frequency plantlet regeneration from inflorescence axis-derived callus cultures of sweet aloe genotype. Competent callus cultures were established on 0.8% agar-gelled Murashige and Skoog’s (MS) basal medium supplemented with 6.0 mg l⁻¹ of 2,4-dichlorophenoxyacetic acid (2,4-D) and 100.0 mg l⁻¹ of activated charcoal and additives (100 mg l⁻¹ of ascorbic acid, 50.0 mg l⁻¹ each of citric acid and polyvinylpyrrolidone, and 25.0 mg l⁻¹ each of l-arginine and adenine sulfate). The callus cultures were cultured on MS medium containing 1.5 mg l⁻¹ of 2,4-D, 0.25 mg l⁻¹ of Kinetin (Kin), and additives with 4% carbohydrate source for multiplication and long-term maintenance of regenerative callus cultures. Callus cultures organized, differentiated, and produced globular embryogenic structures on MS medium with 1.0 mg l⁻¹ of 2,4-D, 0.25 mg l⁻¹ of Kin, and additives (50.0 mg l⁻¹ of ascorbic acid and 25.0 mg l⁻¹ each of citric acid, l-arginine, and adenine sulfate). These globular structures subsequently produced shoot buds and then complete plantlets on MS medium containing 1.0 mg l⁻¹ of 6-benzylaminopurine and additives. A hundred percent regenerated plantlets were hardened in the greenhouse and stored under an agro-net house/nursery. The regeneration system defined could be a useful tool not only for mass-scale propagation of selected genotype of A. vera, but also for genetic improvement of plant species through genetic transformation.     

Efficient synthesis of an ε-hydroxy ester in a space–time yield of 1580 g L−1 d−1 by a newly identified reductase RhCR

A new NADH-dependent carbonyl reductase RhCR capable of efficiently reducing the ε-ketoester ethyl 8-chloro-6-oxooctanoate (ECOO) to give ethyl (S)-8-chloro-6-hydroxyoctanoate [(S)-ECHO], an important chiral precursor for the synthesis of (R)-α-lipoic acid, was identified from Rhodococcus sp. ECU1014. Using recombinant Escherichia coli cells expressing RhCR and glucose dehydrogenase used for the regeneration of cofactor, 440 g L⁻¹ (2 M) of ECOO were stoichiometrically converted to (S)-ECHO in a space–time yield of 1580 g L⁻¹ d⁻¹ without the external addition of any expensive cofactor.     

Crystal Structure of L—arginine Fluoroborate

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Synthesis,structure and magnetic properties of the pentanuclear complex [Fe<Subscript>2</Subscript>(CN)<Subscript>12</Subscript>Ni<Subscript>3</Subscript>(L)<Subscript>6</Subscript>]·27H<Subscript>2</Subscript>O,where L is nitronyl nitroxide

We succeeded in synthesizing a new high-spin complex [Fe₂(CN)₁₂Ni₃(L)₆]·27H₂O, where L is stable nitroxide 2-(imidazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl. According to X-ray diffraction data, the metal core of the pentanuclear [Fe₂(CN)₁₂Ni₃(L)₆] molecule is a trigonal bipyramid with Fe atoms occupying the axial positions and linked via CN bridges to {NiL₂} fragments laying in the equatorial plane. A peculiarity of this coordination compound is a large number of water molecules per the [Fe₂(CN)₁₂Ni₃(L)₆] pentanuclear molecule in the structure. The complex character of the μ_eff(T) dependence points to many competing channels of exchange interactions between the three types of paramagnetic centers.     

Potentiality of independent component regression in assessment of the peaks responsible for antimicrobial activity of <Emphasis Type="Italic">Satureja hortensis</Emphasis> L. and <Emphasis Type="Italic">Oliveria decumbens</Emphasis> Vent. using GC–MS

Satureja hortensis L. and Oliveria decumbens Vent. are used in traditional medicine in the world due to its antifungal, antibacterial and antioxidant properties. In this study, the antimicrobial activities in Satureja hortensis L. and Oliveria decumbens Vent. essential oils against three microbial strains were evaluated by two different methods, including: disk diffusion method and micro-broth dilution assay [with minimal inhibitory concentration (MIC) between 0.025 and 0.500 µL/mL, and minimal lethal concentration (MLC) between 0.050 and 1.000 µL/mL] and qualitative analysis was performed by gas chromatography–mass spectrometry technique (GC–MS). The peaks potentially responsible for the antimicrobial activity in essential oils samples were indicated by some linear multivariate calibration techniques with different preprocessing methods. From the studied techniques, independent component regression (ICR) was preferred to exhibit the potential antimicrobial active compounds in Satureja hortensis L. and Oliveria decumbens Vent. essential oils because of its high repeatability, simplicity, and interpretability of the regression coefficients. Independent components (ICs) can give more chemical explanation than principal components (PCs), because independence is a high-order statistic that is a much stronger condition than orthogonality.     

Partial Characterization of the Proteolytic Properties of an Enzymatic Extract From “Aguama” <Emphasis Type="Italic">Bromelia pinguin</Emphasis> L. Fruit Grown in Mexico

Plant proteases are capable of performing several functions in biological systems, and their use is attractive for biotechnological process due to their interesting catalytic properties. Bromelia pinguin (aguama) is a wild abundant natural resource in several regions of Central America and the Caribbean Islands but is underutilized. Their fruits are rich in proteases with properties that are still unknown, but they represent an attractive source of enzymes for biotechnological applications. Thus, the proteolytic activity in enzymatic crude extracts (CEs) from wild B. pinguin fruits was partially characterized. Enzymes in CEs showed high proteolytic activity at acid (pH 2.0–4.0) and neutral alkaline (pH 7.0–9.0) conditions, indicating that different types of active proteases are present. Proteolytic activity inhibition by the use of specific protease inhibitors indicated that aspartic, cysteine, and serine proteases are the main types of proteases present in CEs. Activity at pH 3.0 was stable in a broad range of temperatures (25–50 °C) and retained its activity in the presence of surfactants (SDS, Tween-80), reducing agents (DTT, 2-mercapoethanol), and organic solvents (methanol, ethanol, acetone, 2-propanol), which suggests that B. pinguin proteases are potential candidates for their application in brewing, detergent, and pharmaceutical industries.     

Effect of mechanical activation of reagents’ mixture on the high-temperature synthesis of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–TiB<Subscript>2</Subscript> composite powder

A powder mixture of Al/TiO₂/H₃BO₃ = 10/3/6 in molar ratio was used in this study to form the Al₂O₃–TiB₂ ceramic composite via thermite reactions (combustion synthesis). As no combustion synthesis occurred for an unmilled sample in a furnace, the mixture was milled in a planetary ball-mill for various milling times, and the as-milled samples were in situ synthesized in the furnace at a heating rate of 10 °C/min. The differential scanning calorimetry (DSC) measurements were performed with the same heating rate on the unmilled and the as-milled samples to evaluate the influences of the milling on the mechanisms and efficiencies of reactions. Although no combustion synthesis occurred for the unmilled sample in the furnace, two exothermic peaks were detected in its DSC curve after the melting of the Al. For the as-milled samples, significant changes revealed in the DSC curves, suggest that the milling process before the combustion synthesis changed the mechanisms and efficiencies of reactions. In addition, the intensity and the temperature of the exothermic peaks in the DSC curves changed by increasing the milling time. According to the XRD analyses, by enhancing the milling time, the purity of the final products would increase, confirming that the efficiency of the reactions increased. Finally, the microstructures of the as-milled and as-synthesized samples were examined by a SEM, and it was shown that the morphology of the reactant powders was altered by increasing the milling time.     

Effect of acid–base characteristics of ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript> on catalytic properties in carboxylation of methanol

We have established that the calcination temperature for ZrO₂–Y₂O₃ catalysts changes their acid–base spectrum, which determines the direction of the conversions in the mixture MeOH + CO₂. For samples with predominance of acid sites, the major product is dimethyl ether. As the content of base sites increases, methyl formate is formed. Activity in dimethyl carbonate synthesis is exhibited only by samples in which the basicity is higher than the acidity or close to it.     

Synthesis,crystal structure of new linear trinuclear isovalence Co(II)([Co<Subscript>3</Subscript>(H–L)<Subscript>2</Subscript>(L)<Subscript>2</Subscript>]), and visualizing intermolecular interactions with Hirshfeld surface method

S-allyl-β-N-[(2-hydroxyphenyl)methylene]hyrazinecarbodithioate) (1, H₂L), the Schiff base of dithiocarbazate with unsaturated allyl substitution, can act as a new tridentate SNO ligand H₂–L and react with cobalt(II) nitrate hexahydrate to form the novel linear trinuclear isovalence Co(II) complex, [Co₃(H–L)₂(L)₂] 2C₂H₅OH (2). The compounds were characterized by elemental analysis, infrared, and ultraviolet spectroscopy. Compound 2 was also characterized by single-crystal X-ray analysis and crystallizes in the orthorhombic space group, Pbcn, with a = 30.643(1) Å, b = 9.118(4) Å, c = 19.017(7) Å, α = β = γ = 90°, V = 5312.95 Å³, Z = 4, and R ₁ = 0.0790, (wR ₂) = 0.1223. The six-coordinate central Co(II) atom is bonded to two deprotonated metal-containing ligands. The terminal Co(II) atoms are in a square planar SNON four-coordinate environment and connected to the central Co(II) by N-atoms from the ligand backbone. For quantifying the intermolecular interactions in crystal lattice, the new d _norm surface and the breakdown of fingerprint plots have been used for visualizing and exploring the compound 2.     

Crystal structures of [RhL<Subscript>4</Subscript>Cl<Subscript>2</Subscript>][AuCl<Subscript>4</Subscript>] (L = Py, γ- and β-picolines) complex salts

New double complex salts [RhL₄Cl₂][AuCl₄] (L = Py, γ- and β-picolines) are synthesized. The compounds are characterized by elemental, powder and single crystal X-ray diffraction analyses. The salts crystallize in different space groups. A specific feature of the packing of [AuCl₄]^– complex anions is the chain formation due to additional Au…Cl or Cl…Cl contacts.