bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bovine Serum Albumin as the Additive of Chiral Mobile Phase for Enantiometric Separation of Dansyl‐Amino Acids with Size‐Exclusion Chromatography
Authors: Liu Fu‐Ken , Wei Guor‐Tzo 
Published: May 2015

AbstractThis work used bovine serum albumin (BSA) as a chiral selector in the mobile phase additive of Size‐exclusion Chromatography (SEC) for enantiomeric separation of Dansyl‐derivative amino acids and the measurement of dissociation constant between Dansyl‐derivative amino acids and BSA. The parameters, such as BSA concentration and buffer concentration, were investigated to obtain the optimized enantiomeric resolution conditions. Also, theoretical descriptions of those parameters' effect on the separation are presented to correlate with experimental results. Baseline resolution of Dansyl‐norvaline, which was used as a model molecule, was obtained with the optimized condition of 80 ppm BSA, 8 mM phosphate at pH 7.4, and 25 °C column temperature. This optimized condition was employed to separate other amino acids. The separation results were then applied to calculate the dissociation constant between the guest molecular (Dansyl‐derivative amino acids) and the host molecular (BSA). The results show that the SEC system can be easily employed for both enantiomeric separation of Dansyl‐amino acids and the measurement of dissociation constants between Dansyl‐amino acids and serum protein.
Single Molecule Fluorescence Spectroscopy
Authors: White J. D. , Hsu J. H. , Wang C. F. , Chen Y. C. , Hsiang J. C. , Su S. C. , Sun W. Y. , Fann W. S. 
Published: May 2015

AbstractSingle molecule spectroscopy can uncover fluctuation averaged out in ensemble measurements. In addition, single molecule spectroscopy naturally implies ultra‐sensitive measurements, which should play important role in future proteomics and genomic research. Fluorescence method is the most commonly used single molecule detection. In this paper, we will use single conjugated polymer fluorescence spectroscopy to illustrate the power of this technique.
Generalized Floquet Formulation of Time‐Dependent Density Functional Theory for Multiphoton Processes in Intense Laser Fields
Authors: Chu Shih‐I , Telnov Dmitry A. 
Published: May 2015

AbstractWe present a short review article of recent new developments of Floquet formulations of time‐dependent density functional theory (TDDFT) for ab initio nonperturbative treatment of multiphoton and high‐order nonlinear optical processes of many‐electron quantum systems in intense laser fields. In the presence of monochromatic or polychromatic (multi‐color) time‐dependent fields, it is shown that the time‐dependent Kohn‐Sham equation can be exactly reformulated as a time‐independent generalized Floquet matrix eigenvalue problem. The theory has been extended to include the time‐dependent current density functional theory (TDCDFT) as well. In the case of bound‐free transition processes such as multiphoton ionization or dissociation, we show that the complex scaling transformation can be implemented into the Floquet formulation of TDDFT and TDCDFT, and the field‐induced complex quasienergy (dressed) states of many‐electron quantum systems can be determined by means of the solution of a time‐independent non‐Hermitian Floquet matrix eigenvalue problem. To facilitate the exploration of the constraints satisfied by the universal but unknown time‐dependent exchange‐correlation energy functionals, we develop several exact relations and theorems for the quasienergy functionals. Finally we present some initial applications of the Floquet‐TDDFT formalism for the study of multiphoton ionization of neutral atoms and electron angular distribution in multiphoton detachment of negative ions in intense laser fields. The Floquet‐TDDFT/TDCDFT formalism provides a powerful new theoretical foundation and feasible procedures for the exploration of many‐electron atomic and molecular physics in strong fields in the future.
Characterization of Sodiated Lipids by Electrospray Ionization‐Quadrupole Ion Trap Tandem Mass Spectrometry
Authors: Ho Yen‐Peng , Huang Ping‐Chen 
Published: May 2015

AbstractCollisionally activated dissociation (CAD) of glycerophosphoglycerol, glycerophosphocholine, glycerophosphoethanolamine, and glycerophosphoserine species was examined using quadrupole ion trap mass spectrometry (QITMS). Since the spectral patterns obtained by QITMS may differ from those obtained using sector or quadrupole mass spectrometry, methods employed in the structure analysis of phospholipids on a sector or quadrupole mass spectrometer are not necessarily useful on an ion trap mass spectrometer. CAD (or MS/MS) of sodiated phospholipids was proposed to structurally analyze phospholipids. The CAD spectra of such ions obtained by QITMS revealed informative ions. Product ions that corresponded to the loss of polar heads identified the lipid classes. Product ions formed by the loss of fatty acyl substituents from sn‐1 and sn‐2 positions were also observed. A preferential loss of the sn‐1 fatty acyl group over the loss of the sn‐2 fatty acyl group was observed among the phospholipid standards examined. This facilitated the determination of the identities and positions of fatty acyl substituents.
The Early Stage of a β‐Hairpin Folding: The Role of Water Molecules
Authors: Li Feng‐Yin , Chen Turning , You Zhi‐Qiang , Mou Chung‐Yuan 
Published: May 2015

AbstractWater has been shown to play a crucial role in stability and catalytical function. Our purpose is to understand the salvation behavior of water molecules during the folding process, in particular, a deca‐peptide β‐hairpin folding. We performed molecular dynamics simulation by employing AMBER6.0 with an explicit water model. The results indicate that water molecules surrounding a biomolecule can be categorized into at least three shells.
Structures and UV‐Visible Absorption Properties of Unsymmetrical Bisdithiolene Nickel Complexes
Authors: Wang Chih‐Chieh , Wu Wei‐Ching , Lee Gene‐Hsiang , Chen Chin‐Ti 
Published: May 2015

AbstractA new unsymmetrical bisdithiolene nickel complex Ni(Et2dazdt)(mnt) was synthesized and structurally characterized, where Et2dazdt and mnt denote 1,4‐diethyl‐perhydrodiazepine‐2,3‐dithione and maleonitrildithiolate, respectively. Its crystal structure and absorption spectrum were determined and compared to those of Ni(Et2pipdt)(mnt), where Et2pipdt is 1,4‐diethyl‐piperazine‐2,3‐dithione. X‐ray diffraction analysis reveals that the Ni(S2C2)2 moiety of Ni(Et2dazdt)(mnt) is not planar due to the twist conformation of a seven‐member ring of Et2dazdt ligand. The twisting of Et2pipdt is less severe and NiS4 center of Ni(Et2pipdt)(mnt) possesses a closer to planar conformation than that of Ni(Et2dazdt)(mnt). Unlike Ni(Et2pipdt)(mnt), Ni(dazdt)(mnt) shows two major separated absorption bands in the visible and near‐IR region, although both absorption bands show negative solvatochromism similar to that of Ni(Et2pipdt)(mnt).
Nonlinear Light Absorption in Porphyrin Derivatives Including the Complexes of the IIIa Metal Group
Authors: Wen T. C. , Hwang L. C. , Lin W. Y. 
Published: May 2015

AbstractThe nonlinear absorption properties of GaClTMPP, InClTMPP and TlClTMPP (TMPP: tetrakis‐(3,4,5‐trimethoxyphenyl)porphyrins) doped in boric acid glass are probed using the Z‐scan technique at different wavelengths. The characteristc of reverse saturable absorption (RSA) is observed at 532 nm, while the two photon absorption (TPA) is dominated at several wavelengths from 840 to 1350 nm. We find that the excited state absorption cross section σex at 532 nm is enlarged along a series of the central metal ions: Ga(III)Cl < In(III)Cl < Tl(III)Cl, and the two‐photon allowed transitions at near infrared are proposed to be 1B*1g ← S0 and 1B*2g ← S0
Influence of Alkanethiols Adsorption on Oxidized Copper Nanoparticles
Authors: Chen Shin‐Fu , Yeh Chen‐Sheng 
Published: May 2015

AbstractAlkanethiols were introduced to study their influence on the oxidized Cu colloids. The XPS measurements have been performed to characterize Cu identities in various stages, i.e. freshly prepared Cu, aged Cu, and aged Cu mixing with alkanethiols. The aged colloidal solutions resulted in CuO growth. The adsorption of alkanethiols on the oxidized copper reduced Cu2+ to Cu1+ with the formation of surface thiolates. Based on the TEM images, addition of alkanethiols yielded a distinct change in the colloidal appearance from aggregation to dispersion.
Optimum Synthesis of Mesoporous Silica Materials from Acidic Condition
Authors: Lin Hong‐Ping , Kuo Chin‐Lung , Wan Ben‐Zu , Mou Chung‐Yuan 
Published: May 2015

AbstractOn the basis of the mixtures composed of CnTMAB/acids/TEOS/water, the mesoporous materials with well‐ordered hexagonal structures can be synthesized under acidic condition (pH < 1.0) with a careful control of the silica condensation. However, the induction period time for the formation of surfactant‐silica precipitation varied with the employed acid source and decreased in the series: HNO3 < HBr < HCl < H2SO4 at the same acid concentration. Increasing the acid concentration not only induced a fast precipitation rate, but also provoked more nuclei seeds formation and reduced the particle size of the mesoporous silica products. A proper aging time is also significant for getting the well‐ordered mesoporous materials via acid route, and a longer aging time would induce a gradual decomposition of the mesostructures. For morphology, in acid synthetic medium, various interesting shell‐like curved patterns on the surface of mesoporous silica particles were formed. The physical properties (such as d‐spacing, pore size, BET surface area and porosity) of the calcined mesoporous silica are almost not affected by the nature of the acid source, but the pore size of the mesoporous materials can be tailored by varying the chain length of the surfactant. Adding the proper amount of ammonia solution for adjusting the pH value between 8–10 can improve the hexagonal mesostructures order of the mesoporous materials while maintaining the original morphology.
Improved Flow Injection Analysis of H2O2 on Cinder/Prussian Blue‐Modified Electrodes by CTAB Micelles
Authors: Zen Jyh‐Myng , Chen Pei‐Yan , Kumar Annamalai Senthil 
Published: May 2015

AbstractIn the present work, a new strategy involving the addition of CTAB at its critical micelle concentration was developed to improve the electrochemical properties of the cinder/PB‐modified screen‐printed electrode (designated as cinder/PB‐SPE) in the detection of H2O2 by flow injection analysis (FIA). Such new PB hybrids derived from cinder have remarkable stability even under strong hydrodynamic stress. The cylindrical CTAB micelles formed at the 2nd critical micelle concentration can effectively promote the PB redox behavior. Under optimized conditions with pH 7 PBS + 7 mM CTAB as carrier solution in FIA, a linear calibration was obtained up to 25 μM H2O2 with slope, regression coefficient, and detection limit (S/N = 3) of 1.03 A/Mcm2, 0.995, and 4.02 μM respectively. Interferences by direct electrochemical oxidation of easily oxidizable substances can be prevented due to the low detecting potential of the working system.
Continuous On‐Line Monitoring of Trihalomethanes in Chlorinated Drinking Water Using an Automated System Based on Pulse Introduction Membrane Extraction and High Speed Gas Chromatography/Mass Spectrometry
Authors: Chang Cheng Chin , Lu Pei Fen , Her Guor Rong 
Published: May 2015

AbstractAn automated system based on pulse sample introduction membrane extraction and gas chromatography/mass spectrometry (GC/MS) has been developed for on‐line monitoring of Trihalomethanes (THMs) in chlorinated drinking water. Pulse samples were injected into the membrane through a sample loop. Zero air was used as the eluent to elute the water samples and also acted as the purging gas. The use of zero air as the purging gas facilitates the cleanup of the membrane to reduce the tailing part of sample input. Under typical operating conditions, the cycle time can be reduced to less than 4 min. The detection limits of this system were found to be about 50 ppt, 50 ppt, 50 ppt, and 20 ppt for CHCl3, CHBrCl2, CHBr2Cl, and CHBr3, respectively. The utility of this system was demonstrated with a ten‐hour on‐line monitoring of THMs in tap water.
Low‐Pressure One‐Step Synthesis of Methyl Isobutyl Ketone from Acetone and Hydrogen over Metal Modified Solid Base Catalysts
Authors: Lin Kai‐Hsim , Ko An‐Nan 
Published: May 2015

AbstractOne‐step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen over metal modified solid base catalysts has been studied at atmospheric pressure and 175–250 °C by using a fixed‐bed, integral‐flow reactor. Two types of catalysts have been utilized: (1) zeolites modified with palladium (Pd/Kβ, Pd/KZSM‐5); and (2) metal oxides modified with sodium and palladium (Pd/Na/MgO, Pd/Na/NaOH/γ‐Al2O3). The catalyst properties were characterized by the methods of atomic absorption, temperature‐programmed desorption and gas adsorption. Sodium vapor deposition on magnesia, followed by impregnation with tetraamine palladium (II) chloride apparently enhances the catalyst basicity as compared with that of magnesia supported palladium. For catalysts with different supports, the base amount decreases in the order of Pd/Na/MgO > Pd/Na/NaOH/γ‐Al2O3 > Pd/KZSM‐5 > Pd/Kβ, in accordance with the catalytic activities. As the amount of sodium or palladium in Pd/Na/MgO increases, the catalyst base amount, acetone conversion and MIBK selectivity are also enhanced to a maximum and then decline. Better catalytic results were attained at a higher pretreating temperature of hydrogen on the catalyst. The optimum conditions for this reaction are 0.5%Pd/0.47%Na/MgO pretreated with hydrogen at 400 °C, reaction temperature 200 °C, acetone/hydrogen mol ratio 1, and W/Fa 6g·h/mol. Under these conditions, the acetone conversion and MIBK yield are 47.3% and 30.7%, respectively, at 480 min time‐on‐stream. The reaction network and reaction mechanism for the formation of MIBK are proposed and discussed.
A New Simple and Accurate Turbidimetric Method for Determination of Ascorbic Acid in Pharmaceuticals and Fruits
Authors: Farajzadeh Mir Ali , Nagizadeh Sepideh 
Published: May 2015

AbstractAn accurate, simple, solvent free and inexpensive turbidimetric method is presented for the determination of ascorbic acid in pharmaceutical preparations and fruits. It needs no special reagents or precautions. In this method HgCl2 oxidizes ascorbic acid in citrate buffer at a pH of about 4 and produced Hg2Cl2 precipitate as monitored by turbidance measurements. The procedure is very simple and the experimental conditions such as temperature, ionic strength, stirring and time are not critical. High sensitivity and selectivity are two other advantages of this method. Linear dynamic range of the calibration curve is between 3–120 μg/mL with limit of detection (LOD) 1 μg/mL, which allows the ascorbic acid contents of most fruits and vegetables to be analyzed. On the other hand, the interference studies show that common compounds in real samples and colored substances have no considerable effect on the determination. Only filtration of some samples is necessary and other treatments, which are performed prior to determination of ascorbic acid by other analytical methods, are eliminated. Finally, ascorbic acid concentration in different samples is determined by the proposed method and obtained results are compared with the results of the official 2,6‐dichlorophenolindophenol or iodimetric methods and a good agreement is obtained. This method is very sensitive in comparison with iodimetry and is very fast relative to the 2,6‐dichlorophenolindophenol method.
Purification ofCandida RugosaLipase Using Agarose Mercurial Column
Authors: Tai Dar‐Fu , Chang Yuan‐Fimg , Chiou Tzyy‐Wen 
Published: May 2015

AbstractCandida rugosalipase from Sigma was subjected to an agarose mercurial column, and the three fractions thus collected were further desalted using a Sephadex G‐25 column. The purification of these isozymes increases their catalytic activities toward the hydrolysis of triacetin. An improved resolution on the hydrolysis of 2‐chloroethyl 2‐phenylpropionate was also observed by utilizing one of the isolated isozymes CRL II.
Formation of ATP by Photochemical Excitation of Benzoquinones in Dimethylacetamide Solution
Authors: Lee Hung‐Wen , Huang Kunpo 
Published: May 2015

AbstractA new method of adenosine triphosphate production is described which involves photo‐excitation of p‐benzoquinones under the presence of adenosine diphosphate and inorganic phosphate in N,N‐dimethylacetamide solution. A possible mechanism for the reaction is presented.
Substitution Coordination Approach for Selective Determination of Complex: Pontachrome Violet SW/Fe(III)/Cu(II) System
Authors: Gao Hong‐Wen , Hu Nai‐Liang 
Published: May 2015

AbstractThe Substitution Coordination for Selective Determination (SCSD) was proposed by studying the complexations of pontachrome violet SW (PCV) with Fe(III) and Cu(II) at pH 5.5. The up dated approach to the de termination of binding constants of a complex was established by the spectral correction technique (SCT). The substitution complexation Cu(II) + Fe(PCV) → Cu(PCV) + Fe(III) has been applied to the direct selective determination of copper traces by the SCT with a high sensitivity.
Four‐ and Five‐Coordinate Gallium Complexes Stabilized by Bidentate 2‐(Dimethylaminomethyl)Pyrrole Ligand: Molecular Structures of Ga[NC4H3(CH2NMe2)‐2]3and GaMe2[NC4H3(CH2NMe2)‐2]
Authors: Yu Ru‐Ching , Huang M‐Hsien , Lee Gene‐Hsiang , Peng Shie‐Ming 
Published: May 2015

AbstractTreatment of GaCl3with one equiv of Li[NC4H3(CH2NMe2)‐2] (n = 1, 2, 3) in diethyl ether at −78 °C yields GaCl3‐n[NC4H3(CH2NMe2)‐2]n(n = 1,1; n = 2,2; n = 3,3). Compound 1 reacts with two equiv of RLi to afford GaR2[NC4H3(CH2NMe2)‐2] (4a, R=Me; 4b, R=Bu) via transmetallation. Reacting 2 with one equiv of RLi in diethyl ether,3and4are formed via ligand redistribution. Variable temperature1H NMR spectroscopic experiments reveal that the five‐coordinate gallium compound3is fluxional and results in a coalescence temperature at 5 °C, at which ΔG≠is calculated at ca. 10.4 Kcal/mole. All the new compounds have been characterized by1H and13C NMR spectroscopy and the structures of compounds3and4ahave also been determined by X‐ray crystallography.
Separation of Dyes from Aqueous Solutions by Paper Adsorption
Authors: Wang Wan‐Kung , Zhou Whe‐Zuang , Huang Whe‐Ling 
Published: May 2015

AbstractSeparation of the dyes methyl violet, methylene blue, and congo red from aqueous solutions by paper capillary permeation adsorption method was studied using paper. Nearly 100% of the investigated dyes could be separated under the optimum conditions. The effect of pH on the separation efficiency was studied in particular. At pH 5–9, 1.3–11, and 7–11, the maximum separation was achieved for methyl violet, methylene blue and congo red, respectively. The effects of dye concentration and some foreign ions on the separatability were examined. Moreover, the selective separation of some dyes was attempted by elution with chemical reagents.
Studies with Alkylheterocycles: Novel Synthesis of Functionally Substituted Isoquinoline and Pyridopyridines Derivatives
Authors: Elmaati Tarek M. Abu , El‐Taweel Fathy M. A. 
Published: May 2015

AbstractSeveral isoquinolines were prepared via reacting pyridine 4 with cinnamonitriles 5a‐c or 5d‐f. Treating 4 with elemental sulphur yielded thienopyridine 9. 9 reacts with acrylonitrile to give isoquinoline 12. 12 was also prepared from 4 and methylenemalononitrile. Condensation of 4 with aromatic aldehydes gave the arylidine 13. 13 afforded the pyridine 14 and 15 on treating it with NH4OH and AcOH/HCl, respectively.
Systematical Synthesis of Distamycin Analogues and Their Interaction with Herring Sperm DNA
Authors: Tang Feili , Wang Jin , Liu Dan , Li Jingjian , Yuan Gu 
Published: May 2015

AbstractA simple procedure for the systematical synthesis of eight distamycin analogues containing N‐methylpyrrole (Py) and N‐methylimidazole (Im) has been developed by a chloroform reaction and DCC coupling reaction without amino protection and deprotection, and the interaction of the analogues with Herring Sperm DNA was investigated by fluorescence spectroscopy.
Synthetic Study of 4‐Substituted Piperidine Ring in Elarofiban, RWJ‐50042, Tirofiban and Paroxetine
Authors: Chang Meng‐Yang , Lin John, Yi‐Chung , Chen Shui‐Tein , Chang Nein‐Chen 
Published: May 2015

AbstractA new strategy for synthesizing a 4‐substituted piperidine ring uses the formal [3+3] cycloaddition reaction as the key protocol. This method provides a convenient formal synthesis of elarofiban, RWJ‐50042, tirofiban and paroxetine.
QSAR Studies on Dipeptides Based on a Combinatorial MHDV‐GA‐MLR Method
Authors: Liu Shu‐Shen , Yin Chun‐Sheng , Wang Xiao‐Dong , Wang Lian‐Sheng 
Published: May 2015

AbstractA combinatorial method for estimating and predicting the biological activities of two sets of dipeptides, a set of 48 compounds and another set of 58, was developed. The molecular holographic distance vector (MHDV) was employed to characterize the structures of the peptide molecules. Preliminary selection of the MHDV descriptors was performed based on the number of the molecules having non‐zero MHDV values. The final optimal descriptors were completed by a genetic algorithm‐based variable selection procedure. Then the optimal descriptors are used to relate to the biological activities of the peptides using the multiple linear regression (MLR) method. For two panels of dipeptides, the correlation coefficient of estimations (r) are respectively 0.9651 for 48 peptides and 0.936 for 58 peptides, and the correlation coefficient of leave‐one‐out predictions (q) are respectively 0.9452 and 0.9075.
Synthesis and Characterization of Phenyl Modified PDMS/PHMS Copolymers
Authors: Yang Mei‐Hui , Lin Hsin‐Tso , Lin Chih‐Chun 
Published: May 2015

AbstractA series of polydimethylsiloxane (PDMS)/polyhydrogenmethylsiloxane (PHMS)/polymethylphenylsiloxane (PMPS) random copolymers with different phenyl contents were synthesized in one step through triflic acid‐catalyzed ring‐opening polymerization of cyclic comonomers and characterized by GPC, IR and NMR. Sequential structures of the random copolymers were determined by 29Si‐NMR spectroscopy. Thermal properties of these copolymers were studied by DSC and TGA. The effect of phenyl moiety on the thermal properties of the copolymers was discussed. The refractive index (nD) increased regularly with the introducing of phenyl‐functionality as expected.
Solvent Effects on the Solvolysis of Some Secondary Tosylates. Applications of YBnOTs and YxBnOTs Scales to Mechanistic Studies
Authors: Liu Kwang‐Ting , Lin Yen‐Shyi , Duann Yeh‐Fang 
Published: May 2015

AbstractThe solvolysis of α‐tert‐butyl‐2‐naphthylmethyl, 9‐fluorenyl, and some 1‐aryl‐1‐tert‐butylmethyl tosylates (8–10) in a variety of solvents were studied. Both the single‐parameter Hammett‐Brown equation and the dual‐parameter Yukawa‐Tsuno equation showed linear correlations. The variation of ρ values was discussed. A new YxBnOTs scale was developed, and the YBnOTs scale was expanded. Solvent effects for a number of tosylates were examined. Excellent linear relationships observed from the single‐parameter Grunwald‐Winstein equation (Eqn. 2) for 9‐fluorenyl tosylate (10) led to the conclusion that the 9‐fluorenyl cation in the solvolysis transition state was unlikely antiaromatic. Anchimeric assistance in the solvolysis of 16–19 was discussed.