bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Anti Tuberculostatic Activity of Novel 1,3,4‐Oxadiazole Derivatives
Authors: Yar M. Shahar , Siddiqui A. Ahmad , Ashraf Ali M. 
Published: May 2015

AbstractA series of novel 2,5‐disubstituted 1,3,4‐oxadiazole derivatives were synthesized and tested for their in vitro antimycobacterial activity. Some compounds showed interesting activity against a strain of Mycobacterium tuberculosis H37Rv. The result of the antimycobacterial activity tests revealed that 2‐(2‐naphthyloxymethyl)‐5‐phenoxymethyl‐1,3,4‐oxadiazole (IVd) exhibited > 90% inhibition at MIC ˜6.25.
Calculation of the Viscosity of Simple Fluids Based on the Rainwater‐Friend Theory
Authors: Hashemi Fariba S. , Tafreshi Saideh S. 
Published: May 2015

AbstractViscosities of noble gases have been calculated over a wide temperature‐pressure range. Simple and accurate Tang‐Toennies potential of the noble gases are used in the Chapman‐Enskog calculation of the zero density viscosity and in the Rainwater‐Friend theory to determine the initial density dependence of the viscosity. At densities beyond the range of the theory (up to 46 mol.dm−3), a variant of the residual viscosity is developed. A correlation function for the calculation of viscosity over the whole range of density is presented. A comparison of the calculated and experimental values of the viscosity yields an average absolute deviation of 1.5%.
Spherical Zinc Oxide Nano Particles from Zinc Acetate in the Precipitation Method
Authors: Hsieh Cheng‐Hsien 
Published: May 2015

AbstractThe liquid precipitation method using zinc acetate dihydrate was applied for the synthesis of uniform and spherical ZnO nanoparticles. The ultrafine zinc oxid was prepared in a water‐ethanol mixture solution. The solution containing zinc cation was soluble in water. The surface‐active agent triethanolamine (TEA) was soluble in ethanol. Then alkali precipitated by adding n‐propylamine. The spherical zinc oxide particle morphology was found to be highly dependent on the zinc salt concentration, ethanol‐water ratio, and the surface‐active agent additive. The process can produce white ZnO powder of 50–90 nm in size. The morphology of zinc oxide showed a powder shape by transmission electron microscopy (TEM), the crystallization phase structure of zinc oxide by X‐ray diffraction (XRD), and the zinc oxide remaining by using an organic analysis by infrared spectroscopy (IR).
Control of Wall Thickness and Extraordinarily High Hydrothermal Stability of Nanoporous MCM‐41 Silica
Authors: Cheng Chi‐Feng , Chou Shu‐Hsien , Cheng Po‐Wen , Cheng Hsu‐Hsuan , Yak Hwa‐Kwang 
Published: May 2015

AbstractWall thickness of siliceous MCM‐41 could be controlled systematically up to 36.1 Å. A reasonable model explaining formation of thicker MCM‐41 walls, not enlarging pore channel is proposed on the basis of TGA and 13C MAS NMR data of samples. Thermal restructuring process under mild basic condition favors the silica redeposition on silica wall and building up thicker wall. Most mesostructure of calcined MCM‐41 with thicker wall was retained even after hydrothermal treatment in boiling water for 14 days. To our best knowledge, the excellent hydrothermal stability of the MCM‐41 silica reported herein has not been described before and facilitates practical applications of mesoporous molecular sieves in future.
Development and Evaluation of a Kinetic‐Spectrophotometric Method for Determination of Arginine
Authors: Mitić Snežana S. , Miletić Gordana Ž. , Pavlović Aleksandra N. , Tošić Snežana B. , Velimirović Dragan S. 
Published: May 2015

AbstractA kinetic method for the determination of micro quantities of amino acid arginine (Arg) is described in this paper. The catalytic activity of cobalt in the reaction of oxidation of purpurin (1,2,4‐trihydroxy‐antraquinone, PP) by hydrogen peroxide in alkaline buffer solution decreases in the presence of micro quantities of arginine, because of the formation of the complex. Operating conditions for the successful determination of arginine were optimized. The optimized conditions yielded a theoretical detection limit of 1.45 μg mL−1. Kinetic equations are proposed for the investigated process. The interference effects of certain foreign ions and amino acids upon the reaction rate were studied and removed in order to assess the selectivity of the method. The developed procedure was successfully applied to the determination of arginine in various pharmaceutical samples. The typical feature of this procedure is that determination can be carried out at room temperature and in a short analysis time. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples.
Novel Metronidazole Membrane Sensor Based on a 2,6‐(p‐N,N‐Dimethylaminophenyl)‐4‐Phenylthiopyrylium Perchlorate
Authors: Ganjali Mohammad Reza , Norouzi Parviz , Faridbod Farnoush , Pirelahi Hooshang 
Published: May 2015

AbstractA novel PVC‐based membrane sensor based on 2,6‐(p‐N,N‐dimethylaminophenyl)‐4‐phenylthiopyrylium perchlorate (DAPP) is described. The electrode exhibits a sub‐Nernstian response to 1‐(beta‐hydroxyethyl)‐2‐methyl‐5‐nitroimidazole (metronidazol) over a relatively wide concentration range (1.0 × 10−1 to 1.0 × 10−5 M) with a detection limit of 8.0 × 10−6 M. The best performance was obtained with the membrane containing 30% poly (vinyl chloride), 50% dibutyl phthalate, 7% DAPP and 13% oleic acid. It has a fast response time (< 30 s) and can be used for at least four weeks without any major deviation. The proposed sensor revealed very good selectivity for metronidazole over a wide variety of common cations, anions and amino acids and could be used in the pH range of 6.0–7.5. It was successfully used for direct determination of metronidazole in an oral synthetic antiprotozoal as an antibacterial agent, in metronidazole tablets, and metronidazole injections and metronidazole gels.
Determination of Cinnarizine in Pure and Pharmaceutical Formulations
Authors: Devagondanahalli Manjunatha Hadagali , Shaikh Sarfaraj Mohd Takhi , Jaldappagari Seetharamappa , Ramanaboyina Sudhir Kumar , Kasalanti Harikrishna 
Published: May 2015

AbstractTwo simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of cinnarizine (CNR) in pure and pharmaceutical formulations. The methods are based on the formation of chloroform soluble ion‐association complexes of CNR with thymol blue (TB) and with cresol red (CR) inNaOAc‐AcOH buffer of pH 3.6 for TB and in KCl‐HCl buffer of pH 1.6 for CR with absorption maxima at 405 nm and at 403 nm for TB and CR, respectively. Reaction conditions were optimized to obtain the maximum color intensity. The systems obeyed Beer's law in the range of 0.6–15.8 and 0.8–16.6 μg mL−1 for TB and CR, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data.
Expression, Purification and Characterization of a Bifunctional α‐L‐Arabinofuranosidase/β‐D‐Xylosidase from Trichoderma Koningii G‐39
Authors: Wan Chin‐Feng , Chen Cheng‐Ta , Li Yaw‐Kuen , Huang Lina 
Published: May 2015

AbstractA gene of α‐L‐arabinofuranosidase (Abf) from Trichoderma koningii G‐39 was successfully expressed in Pichia pastoris. The recombinant enzyme was purified to > 90% homogeneity by a cation‐exchanged chromatography. The purified enzyme exhibits both α‐L‐arabinofuranosidase and β‐D‐xylosidase (Xyl) activities with p‐nitrophenyl‐α‐L‐arabionfuranoside (pNPAF) and 2,4‐dinitrophenyl‐β‐D‐xylopyanoside (2,4‐DNPX) as substrate, respectively. The stability and the catalytic feature of the bifunctional enzyme were characterized. The enzyme was stable for at least 2 h at pH values between 2 and 8.3 at room temperature when assayed for Abf and Xyl activities. Enzyme activity decreased dramatically when the pH exceeded 9.5 or dropped below 1.5. The enzyme lost 35% of Abf activity after incubation at 55 °C for 2 h, but retained 95% of Xyl activity, with 2,4‐DNXP as substrate, under the same conditions. Further investigation of the active site topology of both enzymatic functions was performed with the inhibition study of enzyme activities. The results revealed that methyl‐α‐L‐arabinofuranoside inhibition is noncompetitive towards 2,4‐DNPX as substrate but competitive towards pNPAF. Based on the thermal stability and the inhibition studies, we suggest that the enzymatic reactions of Abf and Xyl are performed at distinct catalytic sites. The recombinant enzyme possesses both the retaining transarabinofuranosyl and transxylopyranosyl activities, indicating both enzymatic reactions proceed through a two‐step, double displacement mechanism.
A New Application of Hexamethylenetetramine‐Bromine Supported onto Wet Alumina as an Efficient Reagent for Cleavage of Phenylhydrazones under Classical Heating and Microwave Irradiation
Authors: Heravi Majid M. , Sabaghiani Ali J. , Bakavoli Mehdi , Ghassemzadeh Mitra , Bakhtiari Khadijeh 
Published: May 2015

Abstract2,4‐Dinitrophenylhydrazones were converted to their parent carbonyl compounds using hexamethylenetetramine‐bromine complex supported onto wet alumina under classical heating and microwave irradiation.
Photoinduced Aromatization of Unsymmetrically Substituted 1,4‐Dihydropyridines
Authors: Memarian Hamid R. , Abdoli‐Senejani Masumeh , Döpp Dietrich 
Published: May 2015

AbstractIrradiation of unsymmetrically substituted 1,4‐dihydropyridines (1b‐1j) while bubbling oxygen or argon through the solution resulted in aromatization to the corresponding pyridine derivatives (3b‐3j). Compound 1a with 2‐nitrophenyl substituent in 4‐position undergoes elimination of water upon irradiation under both oxygen and argon atmospheres and formation of 3a with 2‐nitrosophenyl substituent. On the other hand, irradiation of the compounds 1e, 1k and 1l with 4‐hydroxy‐3‐methoxyphenyl, 5‐methyl‐2‐furyl and 2‐furyl substituent in this position, respectively, resulted in the expulsion of these substituents and formation of a pyridine derivative unsubstituted in position 4, namely compound 2. Chloroform as a solvent causes the photo‐oxidation of these compounds by an electron transfer mechanism which is supported by the formation of dichloromethane according to GC analysis and presence of acid (HCl) in the solution after irradiation.
Simultaneous Determination of Nickel(II) and Copper(II) by Second‐Derivative Spectrophotometric Method in Micellar Media
Authors: Pouretedal Hamid Reza , Rafat Marym 
Published: May 2015

AbstractA second‐derivative spectrophotometric method based on zero‐crossing over technique is developed in simultaneous determination of copper(II) and nickel(II) ions. Methylthymol blue (MTB) as a chromogenic reagent and cetyltrimethylammonium bromide as a surfactant were used, and measurements were carried out in buffered solution at pH 6 and at a temperature of 25 °C. The amplitude of derivative spectra was measured at wavelengths of 631.9 and 587.7 nm for the simultaneous determination of Ni2+ and Cu2+, respectively. Linearity was obtained in the range of 0.5–5.0 μg mL−1 for both ions in the presence of 0.0–5.0 μg mL−1 of the other ion as an interfering ion. IUPAC detection limits for Cu2+ and Ni2+ ions were obtained at 0.48 and 0.43 μg mL−1, respectively. The proposed procedure has been applied successfully for the simultaneous determination of copper and nickel in synthetic binary mixtures and real samples.
Investigation of the Removal of Lead by Adsorption onto 1‐(2‐Thiazolylazo)‐2‐Naphthol (TAN) Imbedded Polyurethane Foam from Aqueous Solution
Authors: Saeed Muhammad Mufazzal , Bajwa Sadia Zafar , Ansari Muhammad Shahid 
Published: May 2015

AbstractA new preconcentration method is presented for lead on TAN‐loaded polyurethane foam (PUF) and its measurement by differential pulse anodic stripping voltammetry (DPASV). The optimum sorption conditions of 1.29 × 10−5 M solution of Pb(II) ions on TAN‐loaded PUF were investigated. The maximum sorption was observed at pH 7 with 20 minutes equilibrated time on 7.25 mg mL−1 of TAN‐loaded foam. The kinetic study indicates that the overall sorption process was controlled by the intra‐particle diffusion process. The validity of Freundlich, Langmuir and Dubinin ‐ Radushkevich adsorption isotherms were tested. The Freundlich constants 1/n and KF are evaluated to be 0.45 ±0.04 and (1.03 +0.61) × 10−3 mol g−1, respectively. The monolayer sorption capacity and adsorption constant related to the Langmuir isotherm are (1.38 ± 0.08) × 10−5 mol g−1 and (1.46 ± 0.27) × 105 L mol−1, respectively. The mean free energy of Pb(II) ions sorption on‐TAN loaded PUF is 11.04 ± 0.28 kJ mol−1 indicating chemisorption phenomena. The effect of temperature on the sorption yields thermodynamics parameters of ΔH, ΔS and ΔG at 298 K that are 15.0 ± 1.4 kJ mol−1, 74 ±5 J mol−1 K−1 and ‐7.37 ± 0.28 kJ mol−1, respectively. The positive values of enthalpy (ΔH) and entropy (ΔS) indicate the endothermic sorption and stability of the sorbed complexes are entropy driven. However, the negative value of Gibb's free energy (ΔG) indicates the spontaneous nature of sorption. On the basis of these data, the sorption mechanism has been postulated. The effect of different foreign ions on the sorption and desorption studies were also carried out. The method was successfully applied for the determination of lead from different water samples at ng levels.
Single Crystal Structure Determination and Molecular Modeling of Ethyl 4‐{[4‐(Dodecanoyloxy)Phenyl]Diazenyl}Benzoate; Various Mesogenic Behaviors from Different Lengths of Alkyl Chains
Authors: Lai Long‐Li , Su Feng‐Ya , Zhan Kai‐Chao , Cai Yi‐Lyang , Liu Yi‐Hung , Wang Yu 
Published: May 2015

AbstractThe molecular stacking and conformation of ethyl 4‐{[4‐(dodecanoyloxy)phenyl]diazenyl}benzoate was established on the basis of crystallographic data and further compared with those of 4‐{[4‐(decanoyloxy)phenyl]diazenyl}benzoate and 4‐{[4‐(octanoyloxy)phenyl]diazenyl}benzoate. The variation of mesogenic behaviors resulting from the different lengths of alkyl chains was also studied.
One‐Pot Synthesis of 6,7‐Fused Steroidal Thiazoles in Cholestane Series
Authors: Mushfiq M. , Mahboob A. 
Published: May 2015

AbstractA convenient one‐pot synthesis of 2′‐amino‐ and 2′‐N‐phenylamino‐5α‐cholest‐6‐eno[6,7‐d]thiazole derivatives 4‐9 are reported. The synthesis involves the reaction of cholestan‐6‐ones 1‐3 with thiourea or phenylthiourea and iodine. The products have been characterized on the basis of IR, 1H‐NMR and Mass, which find support in two cases from comparison with authentic samples.
Solubility Measurements of Surfactants and Dissolution of Cytochrome c in 1,1,1,2‐Tetrafluoroethane Modified with Organic Solvents
Authors: Li Jie‐Ren , Yu Tiing 
Published: May 2015

AbstractThe solubilities of four surfactants, sodium bis‐2‐ethylhexyl sulfosuccinate (AOT), cetyltrimethylammonium chloride, didodecyldimethylammonium bromide, and n‐dodecyltrimethylammonium chloride in liquid refrigerant 1,1,1,2‐tetrafluoroethane (R134a) modified with methanol, ethanol, and 2‐propanol were measured. The measurements were performed under 25 and 50 bar at 25 °C. The solubility of AOT was as high as 92 mM in R134a with addition of 2% ethanol. Cytochrome c molecules were then verified to be soluble in the AOT‐containing and ethanol‐modified R134a solution. Accordingly, liquid R134a is suggested as a potential extraction solvent for hydrophilic compounds.
Sesquiterpene Coumarins from Ferula Foetida
Authors: Abd El‐Razek Mohamed H. , Wu Yang‐Chang , Chang Fang‐Rong 
Published: May 2015

AbstractA thorough investigation of the ethyl acetate soluble fraction from a methanol extract of the resin of Ferula foetida has resulted in the isolation of a new sesquiterpene coumarin namely epi‐conferdione (1), along with four known compounds, colladonin (2), karatavicinol (3), 8‐acetoxy‐5‐hydroxyumbelliprenin (4), and asacoumarin (5). These structures were elucidated on the basis of extensive spectroscopic techniques, including 1D and 2D NMR spectroscopy. The absolute configuration of the new compound was established by circular dichroism (CD).
VSO4.5H2O: A Mild and Efficient Catalyst for Chemo‐Selective Conversion of Aldehydes to 1,1‐Diacetates
Authors: Heravi Majid M. , Bakhtiari Khadijeh , Benmorad Tina , Oskooie Hossein A. 
Published: May 2015

AbstractProtection of aliphatic and aromatic aldehydes as 1,1‐diacetates using VSO4.5H2O under solvent‐free conditions is carried out. The products are obtained in good to excellent yields. Ketones are not affected under these conditions.
Fragmentations of Hydroxymethyl Radical Cation: An Ab Initio Study
Authors: Mai Fu‐Der , Lu Hsiu‐Feng , Li Feng‐Yin , Lin Sheng‐Hsien 
Published: May 2015

AbstractThe probable fragmentation channels of hydroxymethyl radical cation were studied through the H‐and H2‐abstraction and C‐O bond breaking reactions including their related isomerization reactions. The energy barriers for hydroxymethyl cation undergoing isomerization reactions are generally higher than those undergoing the concerted 1,2‐elimination reactions to generate CHO+ and H2. The fragmentation reaction to form CHO+ and H2 through the 1,2‐elimination pathways is the major fragmentation channel for hydroxymethyl cation, consistent with the experimental observation. H abstraction from the hydroxyl group of CH2OH+ is more difficult than that from the methylene group. The feasible path to lose H is to generate CHOH2+ through hydrogen transfer reaction as the first step and then to undergo H‐elimination to generate trans‐CHOH+. Among all the reactions found in this study, the OH‐elimination to generate CH2+ has the highest energy barrier. Our calculation results indicate that the major signals contributed from the related species of hydroxymethyl cation found in the mass spectrum should be m/e 29, m/e 30.
DFT Study of the Group Interactions in 1,3,5‐Triamino‐2,4,6‐Trinitrobenzene and 1,3,5‐Triamino‐2,4,6‐Tridifluoroaminobenzene
Authors: Ju Xue‐Hai , Wang Zun‐Yao , Xiao He‐Ming 
Published: May 2015

AbstractDensity functional calculations on isodesmic disproportionation reactions of 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) and 1,3,5‐triamino‐2,4,6‐tridifluoroaminobenzene (TATDB) indicate that the interaction between nitro groups on meta carbons of TATB, which brings about unstability to the molecule, is surprisingly larger than that between difluroamino groups in TATDB. The electron‐withdrawing and electron‐donating groups generate large positive and very small negative values of Edisproportion, respectively. When both electron‐withdrawing and electron‐donating groups are attached to the benzene skeleton at the same time, large negative disproportionation energy is produced, which stabilizes the derivatives. The values of Edisproportion for TATB and TATDB are predicted to be ‐48.03 kJ/mol and ‐63.54 kJ/mol, respectively, indicating that the total interaction among groups with stabilization effects in TATDB is larger than that in TATB. The large difference of the Edisproportion values between TATB and TATDB is derived from the large difference between the interactions of the meta‐nitro group and those of meta‐difluoroamino groups. The energy barriers for the C‐N internal rotation of NO2 group and NF2 groups are 74.7 kJ/mol and 185.8 kJ/mol for TATB and TATDB, respectively. The large energy barrier for the rotation of the NF2 group is caused by its stabilization interaction with neighbor amino groups, instead of steric effects. When the number of pairs of amino‐nitro or amino‐difluoroamino groups increases, there are more negative charges on the NO2/NF2 groups and on the O/F atoms.
Interaction of Dipalmitoyl Phosphatidylcholine with n‐Hexadecanol in Monolayer and Liposome
Authors: Chen Yu‐Chian , Chang Chien‐Hsiang , Yang Yu‐Min , Maa Jer‐Ru , Lin Jing‐Li , Wu Chieh‐Hsi 
Published: May 2015

AbstractThe monolayer collapse behavior of n‐hexadecanol/dipalmitoyl phosphatidylcholine (DPPC) was investigated in this study at the air/water interface at 37 °C. Surface pressure variations with time for the mixed monolayers of DPPC with 20 mol% and 50 mol% n‐hexadecanol at corresponding collapse points were recorded by a Langmuir trough system. In addition, the interaction of n‐hexadecanol with a pure DPPC monolayer was identified by fluorescence microscopy (FM). The results demonstrated distinct differences between these systems; according to our observation, the higher the ratio of n‐hexadecanol to DPPC, the more nucleation domains can be induced. The FM images demonstrated that pronounced domain formation was associated with a longer relaxation time of the collapsed DPPC and DPPC/n‐hexadecanol monolayers, and the presence of n‐hexadecanol appeared to enhance the relaxation processes. The liposome was prepared by the thin‐film hydration method. The average diameter of DPPC and DPPC/n‐hexadecanol liposomes was investigated by dynamic light scattering. It is shown that the diameter of DPPC liposome with n‐hexadecanol is smaller than pure DPPC liposome at the initial state. After 24 hours, DPPC/n‐hexadecanol liposome became larger than pure DPPC liposome and lasted for the next four days. The effects of a greater ratio of n‐hexadecanol did not play an important role in DPPC liposome formation based on our dynamic light scattering analysis. Our result demonstrated that n‐hexadecanol might affect the DPPC liposome stability. The increased ratio of n‐hexadecanol in DPPC liposomes could only a play a minor role in DPPC liposome fusion.
Effect of Environmental Pollution on Heavy Metals Content of Withania Somnifera
Authors: Khan Murad Ali , Ahmad Ijaz , Rahman Inayat Ur 
Published: May 2015

AbstractHeavy metals were investigated in the medicinal plant Withania somnifera as well as of the soil it was grown in using atomic absorption spectrophotometer. The plant samples were collected from three different locations of N.W.F.P, Pakistan. The plant parts including roots, stem, leaves and fruits were found to have the quantity of heavy metals corresponding to their content in the soil. The purpose of the study is to create awareness among people about the proper use and collection of medicinal plants containing high levels of heavy metals and their adverse health affects.
Simultaneous Measurement of Urinary Ketamine, Norketamine, and Dehydronorketamine by Liquid Chromatography‐Atmospheric Pressure Chemical Ionization Mass Spectrometry
Authors: Wu Gong‐Jhe , Chan Han , Lee Maw‐Rong , Chen Chung‐Yu , Yang Dar‐Yu , Cheng Fu‐Chou 
Published: May 2015

AbstractA liquid chromatography/atmospheric pressure ionization mass spectrometry has been developed for the determination of ketamine, norketamine, and dehydronorketamine in human urine. A separation of these analytes in urine samples without tedious pretreatment procedures has been achieved within 10 min. Linear calibration curves of these analytes with coefficients better than 0.998 have been obtained over a wide range from 12.5 to 200 ng/mL. The accuracy was between 2.1% and 7.2% with detection limits at levels of 0.02 ng/mL, 0.02 ng/mL and 0.93 ng/mL for ketamine, norketamine and dehydronorketamine, respectively. The results demonstrate the suitability of the liquid chromatography/atmospheric pressure ionization mass spectrometry approach to analyze trace ketamine, norketamine and dehydronorketamine in urine. Urinary ketamine and norketamine levels were relatively low at 4–24 h intervals and were difficult to assay in a normal laboratory. In the present study, the determination of urinary dehydronorketamine levels at 2–24 hours appears to have a great potential for use in Schedule III controlled drugs management.