bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low‐Molecular Weight and Oligomeric Components in Secondary Organic Aerosol from the Photooxidation of p‐Xylene
Authors: Huang Ming‐Qiang , Zhang Wei‐Jun , Hao Li‐Qing , Wang Zhen‐Ya , Zhao Wen‐Wu , Gu Xue‐Jun , Fang Li 
Published: May 2015

AbstractA laboratory study was performed to investigate the composition of secondary organic aerosol (SOA) products from photooxidation of the aromatic hydrocarbon p‐xylene. The experiments were conducted by irradiating p‐xylene/CH3ONO/NO/air mixtures in a home‐made smog chamber. The aerosol time‐of‐flight mass spectrometer (ATOFMS) was used to measure the size and the chemical composition of individual secondary organic aerosol particles in real‐time. According to a large number of single aerosol diameters and mass spectra, the size distribution and chemical composition of SOA were determined statistically. Experimental results showed that aerosol created by p‐xylene photooxidation is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e. PM2.5), and aromatic aldehyde, unsaturated dicarbonys, hydroxyl dicarbonys, and organic acid are major product components in the SOA after 2 hours photooxidation. After aging for more than 8 hours, about 10% of the particle mass consists of oligomers with a molecular mass up to 600 daltons. The possible reaction mechanisms leading to these products are also proposed.
The Chemistry of Stable Silabenzenes
Authors: Tokitoh Norihiro , Wakita Keiji , Matsumoto Takeshi , Sasamori Takahiro , Okazaki Renji , Takagi Nozomi , Kimura Masahiro , Nagase Shigeru 
Published: May 2015

AbstractStable silabenzenes (1a; R = Tbt, 1b; R = Bbt) were synthesized by taking advantage of extremely bulky and efficient steric protection groups, 2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6‐bis‐[bis(trimethylsilyl)methyl]‐4‐[tris(trimethylsilyl)methyl]phenyl (Bbt). The structure of Tbt‐substituted 1a was determined by X‐ray crystallographic analysis, which demonstrated the complete delocalization of the π‐electrons of the silabenzene ring. It was found that silabenzene 1a reacted with C–C and C–O multiple bond compounds to give the corresponding [4+2]‐cycloadducts via 1,4‐addition, while 1a underwent both 1,2‐ and 1,4‐additions by the reaction with methanol. Silabenzene 1a dimerized very gradually to afford its [4+2]‐dimer, although 1b showed no change under the same conditions. Photochemical reaction of 1a gave the corresponding silabenzvalene isomer instead of the Dewar silabenzene isomer.
Direct Preparation of Metal Ions‐Doped Manganese Oxide by Cyclic Voltammetry
Authors: Ding Ke‐Qiang 
Published: May 2015

AbstractIn this work, for the first time, copper ions(II) and cobalt ions(II) were successfully electrodepositioned into manganese oxide by cyclic voltammetry (CV), respectively. The results obtained from energy dispersive X‐ray analysis (EDX) testified that copper ions and cobalt ions were doped into manganese oxide, and the images, taken from scan electron spectroscopy (SEM) also proved that the morphology of the resultant MnO2 was altered by the doped metal ions to some extent. Interestingly, specific capacitance, obtained by cyclic voltammograms (CVs), for the metal ions‐doped MnO2 exhibited a higher value compared to the non‐doped MnO2. Developing a novel and simple method to generate the metal ions‐doped MnO2 to improve the characteristics of MnO2 is the main contribution of this work.
Spectrophotometric Determination of Esomeprazole Magnesium in Commercial Tablets Using 5‐Sulfosalicylic Acid and N‐Bromosuccinimide
Authors: Rahman Nafisur , Bano Zehra , Azmi Syed Najmul Hejaz 
Published: May 2015

AbstractTwo simple, sensitive and economical spectrophotometric methods have been developed for the determination of esomeprazole magnesium in commercial dosage forms. Method A is based on the reaction of esomeprazole magnesium with 5‐sulfosalicylic acid in methanol to form a yellow product, which absorbs maximally at 365 nm. Method B utilizes the reaction of esomeprazole magnesium with N‐bromosuccinimide in acetone‐chloroform medium to form α‐bromo derivative of the drug peaking at 380 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration ranges of 2‐48 and 10‐100 μg mL−1 with molar absorptivity of 2.11 × 104 and 4.57 × 104L mol−1 cm−1 for methods A and B, respectively. The limits of detection for methods A and B are 0.35 and 0.46 μg mL−1, respectively. No interference was observed from excipients commonly present in tablet formulations. Methods A and B are successfully applied to the commercial tablets for the estimation of esomeprazole magnesium with good accuracy and precision. The results compare favorably with the reference spectrophotometric method indicating no significant difference between the methods compared.
Detection of Chitinolytic Enzymes in Ipomoea Batatas Leaf Extract by Activity Staining after Gel Electrophoresis
Authors: Liau Chun‐Yi , Lin Chung‐Sheng 
Published: May 2015

AbstractA non‐denatured SDS‐PAGE followed by in‐gel activity staining using embedded glycol chitin as a substrate was used to identify the proteins with chitinolyitc activities from sweet potato leaf extract. At least two chitinase activity zones can be clearly identified on the gel at positions with estimated molecular weights of 54.1∼55.6 kDa and 39.6 kDa. Furthermore, our data also indicate that the activity of the larger one can withstand the standard SDS‐PAGE sample preparation. Both of these chitinases, however, are different from that of the previously identified chitinase in sweet potato leaves, which has a molecular weight of 16 kDa. By using an embedded substrate, our method has superior sensitivity in detecting chitinases with higher molecular weights. It is a simple, affordable way and may aid in the future discovery of new chitinases.
Influences of Seven Taiwan‐Produced Adulterants on Gas Chromatographic‐Mass Spectrometric (GC‐MS) Urinalysis of Amphetamines
Authors: Chou Su‐Lien , Ling Yong‐Chien , Yang Mo‐Hsiung , Giang Yun‐Seng 
Published: May 2015

AbstractThis study was conducted to better understand the influences exerted by seven Taiwan‐produced adulterants on the forensic gas chromatographic‐mass spectrometric (GC‐MS) confirmatory urinalysis of amphetamines. The results verified that, when added at 5‐15% (w/w), chlorine bleach would lower the GC‐MS outcomes of the spiked and case specimens by 36‐63%, and was most likely to cause false negatives. Liquid soap, potassium dichromate, soda water for drinking, and tap water would decrease the GC‐MS outcomes by 9‐29%, 8‐20%, 8‐20%, and 5‐16%, respectively, and also had the risk of negating near‐cutoff initial positives into false confirmatory negatives. The negative‐directing effects were mostly due to degradation of analytes and/or deactivation of the derivatizing agent by oxidizing adulterants and/or dilution of analytes by the added liquid. Alum and table salt added as powder had little impact on the test. Responsible institutions and relevant laboratories should face the facts seriously and include the specimen validity testing (SVT) battery in the routine drug testing procedures.
Studies on Liquid‐Liquid Extraction and Recovery of Bismuth(III) from Succinate Media Using 2‐Octylaminopyridine in Chloroform
Authors: Mane Chandrashekhar P. , Anuse Mansing A. 
Published: May 2015

AbstractA procedure is described for the liquid‐liquid extraction and recovery of bismuth(III) from succinate solution using 2‐octylaminopyridine (2‐OAP) as an extractant. The quantitative extraction of bismuth(III) occurs from 0.004 to 0.007 M sodium succinate solution of pH 2.5‐10 using 0.036 M 2‐OAP in chloroform. The extracted metal ion has been recovered by stripping with (3 × 10 mL) 0.5 M nitric acid. The log‐log plot of distribution ratio versus succinate concentration and distribution ratio versus 2‐OAP concentration gave slopes of 2.0 and 0.9, respectively, indicating a metal‐succinate ratio of 1:2 and a metal: 2‐OAP ratio of 1:1.The ion pair complex has a high distribution ratio in chloroform, while other solvents are poor. The extractants are stable towards prolonged acid contacts and there is no loss in its extraction efficiency even after recycling ten times. The extraction behaviour of some commonly associated metal ions, namely Ga(III), Cd(II), Zn(II), Cr(VI), Cu(II), Ba(II), Sb(III), Sn(IV), Tl(I) and Pb(II), has also been investigated. Based on partition data, conditions have been identified for attaining some separations of bismuth(III) from other metal ions; these conditions are extended for the recovery of pure bismuth from ore and alloys. Thermodynamic quantities for the extraction process were calculated.
Bioactive Components from the Mycelium of Antrodia Salmonea
Authors: Shen Chien‐Chang , Lin Chwan‐Fwu , Huang Yu‐Ling , Wan Shr‐Ting , Chen Chin‐Chu , Sheu Sen‐Je , Lin Yi‐Chin , Chen Chien‐Chih 
Published: May 2015

AbstractThree new compounds, 2,4‐dimethoxy‐6‐methylbenzene‐1,3‐diol (1), salmoquinone (2), and 3‐(4‐hydroxyphenyl)‐4‐isobutyl‐1H‐pyrrole‐2,5‐dione (3), together with six known compounds, 2‐methoxy‐6‐methyl‐p‐benzoquinone (4), 2,3‐dimethoxy‐5‐methyl‐p‐benzoquinone (5), 2‐hydroxy‐5‐methoxy‐3‐methyl‐p‐benzoquinone (6), eburcoic acid (7), fomefficinic acid C (8), and a pyrroledione (9), were isolated from the mycelium of Antrodia salmonea. The structures of these compounds were elucidated by spectrometric analyses including IR, NMR, and MS. Among these compounds, 4 and 5 exhibited cytotoxicity against KB, HepG2, and H2058 cell lines.
Efficient, Convenient and Mild Three‐Component Template Preparation and Characterization of Some New Schiff Base Complexes
Authors: Naeimi Hossein , Barzoky Maryam Nejati 
Published: May 2015

AbstractA few kinds of novel Schiff base complexes have been prepared by three‐component reaction of the substituted hydroxyacetophenone with several aliphatic diamines and transition metals such as; Cu(II), Co(II), Mn(II), Zn(II) and UO2(II) under mild reaction conditions. The products have been afforded with excellent yields and appropriate reaction times. The structures of these ligands have been characterized by their IR, 1H NMR, 13C NMR and MS spectral and physical data.
Diversity of Chemical Constituents from Saxifraga Montana H.
Authors: Liu Jun‐Xi , Di Duo‐Long , Shi Yan‐Ping 
Published: May 2015

AbstractA thorough phytochemical investigation of the whole plant of Saxifraga montana H. afforded a new glucoside, methyl 6″‐O‐(E)‐p‐hydroxycinnamoxyl‐glucosyringate (1), and seventeen known natural products, 3‐methyl‐6‐methoxy‐3,4‐dihydroisocoumarin‐8‐O‐β‐D‐glucospyranoside (2), gallic acid (3), glucosyringic acid (4), daphnoretin (5), chamaejasmoside (6), myricetin (7), quercetin (8), quercetin‐3‐O‐β‐D‐galactopyranoside (9), quercetin‐3‐O‐α‐L‐arabinoside (10), quercetin‐3‐O‐β‐D‐glucospyranoside (11), rutin (12), quercetin‐3‐O‐β‐D‐glucopyranosyl (6‐1) glucopyranoside (13), ursolic acid (14), 5,28‐stigmastadien‐3β‐ol (15), β‐sitosterol (16), β‐daucosterin (17), 6′‐palmitoxyl‐β‐daucosterin (18). On the basis of various spectroscopic methods, especially intensive 2D‐NMR (COSY, HMQC and HMBC), FAB‐MS and HR‐ESI‐MS techniques, their structures were elucidated.
1H NMR, IR and UV/VIS Spectroscopic Studies of Some Schiff Bases Derived from 2‐Aminobenzothiazole and 2‐Amino‐3‐Hydroxypyridine
Authors: Issa Raafat M. , Khedr Abdalla M. , Rizk Helen 
Published: May 2015

AbstractBy condensing 2‐aminobenzothiazole with 2‐hydroxy‐1‐naphthaldehyde, 2‐hydroxybenzaldehyde, 4‐methoxybenzaldehyde, 4‐hydroxybenzal‐dehyde, benzaldehyde and 4‐dimethylaminobenzaldehyde, and five Schiff bases Ia‐Ie are prepared. Also, two Schiff bases IIa and IIb are prepared by condensation of 2‐amino‐3‐hydroxypyridine with 2‐hydroxy‐1‐naphthaldehyde and 2‐hydroxybenzaldehyde. The 1H NMR, IR and UV/Vis spectra of these seven Schiff bases are investigated. The signals of the 1H NMR spectra as well as the important bands in the IR spectra are considered and discussed in relation to molecular structure. The UV/Vis absorption bands in ethanol are assigned to the corresponding electronic transitions and the electronic absorption spectra of Schiff bases Ib and IIb are studied in organic solvents of different polarities. The UV/Vis absorption spectra of 2‐amino‐3‐hydroxypyridine Schiff bases IIa and IIb are investigated in buffer solutions of different pH values containing 5% (v/v) methanol, and the results are utilized for the determination of pKa and ΔG* of the ionization of the phenolic OH‐groups. The fluorescence spectra of IIa and IIb are studied in organic solvents of different polarities.The obtained spectral results are confirmed by some molecular calculations using the atom super position and electron delocalization molecular orbital theory for the Schiff base IIb.
Temperature Effects on Structural and Functional Properties of Rat Lens Phe71 Mutant αA‐Crystallins
Authors: Yan Ker‐Ming , Huang Show‐Huey , Subhan D. , Huang Fu‐Yung 
Published: May 2015

AbstractIn order to explore whether hydrophobicity or charge at the 71th residue is important for chaperone‐like activity, wild type (wt) and two mutant αA‐crystallins, F71W and F71R, with an extra 11 residues including 6 histidines tagged at the N‐terminal were prepared. Chaperone‐like activity toward dithiotreitol (DTT) induced insulin aggregation showed the 11 extra residues had little effect. The activity for F71W was as active as the wild type, while F71R was much less active. For the wild type and F71W, the activity increased with the increase of molar quantity; surprisingly, for F71R it caused a drastic decline. ANS fluorescence measurements showed F71R had the highest surface hydrophobicity, suggesting positive charge at this site caused the conformational alteration leading to the increase of hydrophobicity and this hydrophobicity resulted in the formation of high molecular weight aggregates (> 2000 kDa) observed from the thermal stability study. The thermal stability study revealed F71W was the most thermally stable crystallin. Chaperone‐like activity studies at various temperatures suggested the monomer and oligomer, 650 kDa, were responsible for chaperone function and surface hydrophobicity was not the prerequisite for activity. Near‐UV CD studies showed β‐sheet was the major secondary structure for all three crystallins and F71R had a higher percentage of random coil.
Fast Analysis of Free Amino Acids in Tobacco by HPLC with Fluorescence Detection and Automated Derivatization
Authors: Zhu Xiao‐Lan , Zhu Qing‐Sheng , Gao Yun 
Published: May 2015

AbstractA fast, simple, and sensitive HPLC method for the determination of free amino acids in tobacco was described. A fully automated sample processor performed precolumn derivatization of both primary and secondary amino acids with o‐phthalaldehyde/3‐mercaptopropionic acid and 9‐fluorenylmethyl chloroformate (FMOC‐Cl), respectively. All reactions were fully automated by means of an injector programme and accomplished in 10 min. Sample preparation consisted of a single step of extraction with 0.1 mol/L HCl at ambient temperature (assisted by sonication) in 30 min, followed by filtration of an aliquot and derivatization. By optimization of sample preparation and HPLC conditions, separation of 20 amino acids in 30 min was achieved. Detection limits ranged from 0.50 to 1.40 μg/g; coefficients of variation ranged from 1.8% to 3.9%; recoveries ranged from 84.6% to 108.5%. The method was applied to the analysis of amino acids contents of tobacco leaves in different varieties and flue‐curing period.
A Novel Ion‐Selective Electrode for Determination of the Mercury(II) Ion Based on Schiff Base as a Carrier
Authors: Zhang M. , Wu X. , Chai Y. Q. , Yuan R. , Ye G. R. 
Published: May 2015

AbstractA new poly(vinyl chloride) (PVC) membrane ion‐selective electrode based on bis‐salicyladehyde‐diaminjodipropylamine (BSDDA) as an ion carrier was successfully applied to the detection of Hg2+ ions. This electrode displayed good selectivity toward Hg2+ in comparison with other metal ions and exhibited a Nernstian slope of 30.5 ± 0.4 mV per decade of Hg2+ over a concentration range of 9.5 × 10−7 to 6.4 × 10−2 M of Hg2+ in the pH range 1.5 to 3.5. The detection limit was 7.0 ± 0.2 × 10−7 M and response time was about 10 s to 25 s. The electrode can be used at least 2 months without apparent divergence in potential. In addition, the effects of experimental parameters such as membrane composition, nature and amounts of plasticizer and additive were investigated. The proposed electrode could be used as an indicator electrode in the detection of Hg2+ in samples.
Simultaneous Determination of Aluminum, Cadmium and Lead in Whole Blood by Simultaneous Atomic Absorption Spectrometry with Oxygen Charring
Authors: Tsay Tong‐Shung , Huang Yeou‐Lih , Tseng Wei‐Chang 
Published: May 2015

AbstractA method for the simultaneous determination of aluminum (Al), cadmium (Cd) and lead (Pb) in whole blood has been developed by using simultaneous atomic absorption spectrometry (SIMAAS) with oxygen charring. The optimized conditions for the simultaneous determination of Al, Cd and Pb were obtained in the presence of palladium (Pd) as the chemical modifier, using 600 °C and 2400 °C as the pyrolysis and the atomization temperature, respectively. The whole blood samples were diluted 1+5 (v/v) directly with 0.1% (v/v) Triton X‐100. Oxygen was employed to eliminate the interference of carbonaceous residues in the charring step before pyrolysis. The calibration curves were carried out with aqueous standard solutions and the linear ranges were 0–40 ng mL−1, 0–4 ng mL−1 and 0–40 ng mL−1 for Al, Cd and Pb, respectively. The detection limits were 0.96 ng mL−1 (19.2 pg) for Al, 0.03 ng mL−1 (0.6 pg) for Cd and 0.60 ng mL−1 (12.0 pg) for Pb. The spiked recoveries of Al, Cd and Pb in whole blood were 98.0%, 100.0% and 101.7%, respectively. The accuracy of the proposed method was evaluated with the analysis of a whole blood certified reference material (Seronorm, level 2). The found concentrations were in agreement with the recommended values. The proposed method has been successfully applied to the simultaneous determination of Al, Cd and Pb in whole blood of healthy volunteers before and after eating barbecued foods.
QSAR Study of Anti‐HIV Activities against HIV‐1 and Some of Their Mutant Strains for a Group of HEPT Derivatives
Authors: Zarei Kobra , Atabati Morteza 
Published: May 2015

AbstractA quantitative structure activity relationship analysis (QSAR) has been applied to a data set of 23 derivatives of 1–2‐[(hydroxyethoxy)methyl]‐6‐(phenylthio)thymine (HEPT) with their anti‐HIV activities. Semi‐empirical quantum chemical calculations at the AM1 level were used to find the 3D geometry of the studied molecules. Whole numbers of descriptors were calculated with Dragon software, and a subset of calculated descriptors was selected from 1481 Dragon descriptors with the forward stepwise multiple linear regression (MLR) method. Then anti‐HIV activities against HIV‐1 and four HIV‐1 mutant strains containing single mutations in their reverse transcriptases (RTs) were studied, and five equations with excellent statistical qualities were obtained using multiple linear regression. The activities of these compounds were also calculated in predictions, and good correlation coefficients were obtained.
Non‐Covalent Functionalization of Carbon Nanotubes with Surfactants and Polymers
Authors: Hu Chang‐Yuan , Xu Ya‐Juan , Duo Shu‐Wang , Zhang Rong‐Fa , Li Ming‐Sheng 
Published: May 2015

AbstractCarbon nanotubes (CNTs) possessing unique structure and properties are attractive building blocks for novel materials and devices of important practical interest. However, the insolubility or poor dispersibility of pristine CNTs in common solvents poses a serious obstacle to their further development. To effectively utilize CNTs as building blocks for nanotechnology, CNTs have been covalently and noncovalently functionalized in a number of ways to render them soluble in aqueous or organic solutions. Here, we review recent progress and advances that have been made on dispersion of carbon nanotubes in aqueous and organic media by non‐covalent functionalization with surfactants and polymers.
Electrochemical Behavior of Apigenin at a Glassy Carbon Electrode and its Analytical Application
Authors: Xing Tian‐Lai , Wang Fei , Mao Yue‐Ying , Wang Li‐Ping , Ye Bao‐Xian 
Published: May 2015

AbstractThe electrochemical behavior of the antitumor herbal drug apigenin was studied in 0.1 mol L−1 B‐R buffer solutions (50% ethanol, pH 3.0) by cyclic voltammetry (CV) at a glassy carbon electrode. In CV, two oxidation peaks (P1 and P2) with Ep1 = 1.03V and Ep2 = 1.23 V appeared at a scan rate of 0.05 V s−1, and a new electroanalytical method for this herbal drug was established according to the oxidation peak P2. The peak currents have a linear relationship with apigenin concentration in a range from 9.0 × 10−7 to 2.0 × 10−5 mol L−1. Using the established method, apigenin in a herbal drug was determined without pre‐separation with satisfactory results. Moreover, the electrode dynamics parameters were also investigated by electrochemical techniques and the possible electrode reaction mechanism was deduced.
SnCl4/SiO2: An Efficient Heterogeneous Alternative for One‐Pot Synthesis of β‐Acetamidoketones
Authors: Mirjalili Bi Bi Fatemeh , Hashemi Mohammad M. , Sadeghi Bahareh , Emtiazi Hamideh 
Published: May 2015

AbstractEnolizable ketones have been reacted in a one‐pot method with aromatic aldehydes, acetyl chloride and acetonitrile at room temperature in the presence of SnCl4/SiO2 to furnish the corresponding β‐acet‐amidoketones in improved yields. Acetylation of an aromatic hydroxyl group was observed while using 4‐hydroxybenzaldehyde or vanillin and the corresponding β‐acetamidoketones were isolated in an excellent yield.
Efficient Synthesis of 2‐Aminothiazoles and Fanetizole in Liquid PEG‐400 at Ambient Conditions
Authors: Lin Pei‐Ying , Hou Rei‐Sheu , Wang Huey‐Min , Kang Iou‐Jiun , Chen Ling‐Ching 
Published: May 2015

AbstractA simple and practical procedure for the synthesis of 2‐aminothiazoles from α‐tosyloxyketones and thioureas is described using PEG‐400[poly(ethylene glycol‐400)] at ambient conditions. The developed protocol is successfully applied for the preparation of an anti‐inflammatory drug, Fanetizole.
Spectrofluorimetric and Spectrophotometric Determination of Oxamniquine in Pharmaceuticals and Biological Fluids via Derivatization with 4‐Chloro‐7‐Nitrobenzo‐2‐oxa‐1,3‐Diazole (NBD‐Cl)
Authors: El‐Enany N. , Ahmida N. , Belal F. 
Published: May 2015

AbstractSpectrophotometric and spectrofluorimetric methods were developed for the determination of oxamniquine (OXM). Both methods are based on coupling with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl) in borate buffer of pH 7.6, and the reaction product was measured at 400 nm (Method I). The same product was measured by spectrofluorimetry at 480 nm upon excitation at 400 nm (Method II). The absorbance and the fluorescence intensity were enhanced by addition of sodium dodecyl sulphate (SDS). The absorbance‐concentration plot is rectilinear over the range of 5–25 μg/mL with an LOD of 0.31 μg/mL. The fluorescence‐concentration plot is linear over the range of 0.2–1.2 μg/mL with an LOD of 0.03 μg/mL. Both methods were applied to the analysis of capsules, and the results were in good agreement with those obtained using the official method. The method was applied to spiked human plasma; the mean % recovery (n = 5) is 101.05 ± 1.65. A proposal of the reaction pathway is presented.