bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of macroporous poly(N‐isopropylacrylamide) hydrogel with ultrarapid swelling–deswelling properties
Authors: Zhao Qian , Sun Jianzhong , Zhou Qiyun 
Published: March 2007

AbstractA novel technique to synthesize a macroporous poly(N‐isopropylacrylamide) hydrogel with ultrarapid swelling–deswelling properties by using dodecyl dimethyl benzyl ammonium bromide (DDBAB) during the polymerization/crosslinking reaction at −8°C was proposed. A hydrophobic initiator dodecyl dimethyl benzyl ammonium persulfate (APS) was proved to be produced in situ by the reaction of DDBAB and the water‐soluble initiator APS and a heterogeneous initiation mechanism was proposed. The scanning electron microscope and environmental scanning electron microscope images showed that the pore size of the hydrogel increased with increase of the amount of DDBAB. The macroporous structure of hydrogel induced a large swelling ratio and rapid swelling–deswelling rate, since the free water could diffuse very quickly through the macroporous network. The time required from equilibrium swollen state to equilibrium shrunken state was only about 1 min and vice versa. The oscillating swelling–deswelling measurements showed that this macroporous hydrogel could be used repeatedly. These properties of ultrarapid response and reversibility are advantageous for several technical applications, as a kind of biomaterials, both in medicine and in biotechnology. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4080–4087, 2007
Preparation and photophysical behaviors of fluorescent chitosan bearing fluorescein: Potential biomaterial as temperature/pH probes
Authors: Guan Xiaolin , Liu Xinyu , Su Zhixing 
Published: March 2007

AbstractA novel method for attaching fluorescein (via its epoxy derivative) to water‐soluble chitosan, and the temperature/pH‐sensitive qualities of fluorescence were investigated. 3‐Epoxypropoxy fluorescein (EPF) was firstly synthesized by the reaction between fluorescein and epichlorohydrin, and then water‐soluble chitosan bearing fluorescein (CS‐EPF) was prepared via ring‐opening reaction with EPF. They were characterized by the methods of 1H NMR, MS, IR, UV–Vis, and luminescence spectra, respectively. The chemiluminescent and photophysical behaviors of EPF and CS‐EPF were studied in detail. The results showed that the fluorescent chitosan could still provide temperature and pH sensitivities similar to that of fluo‐ rescein, achieving better long‐term stability and fast equilibrium response. CS‐EPF had an excellent linear response between relative fluorescence intensity and temperature in the range of 0–60°C and two linear relationships between relative fluorescence intensity and pH in 0.0–4.14 and 8.15–13.20, respectively. This investigation may provide a convenient way to prepare low‐cost and multifunctional macromolecule biomaterial to probe pH and temperature in biological systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3960–3966, 2007
Synthesis and characterization of a poly(ethylene glycol) prepolymer to be applied as a bioadhesive
Authors: Ferreira P. , Coelho J. F. J. , Pereira R. , Silva António F. M. , Gil M. H. 
Published: March 2007

AbstractSurgical adhesives can be applied to wound closure and to covering and protecting surface wounds. Depending on their degradability, they can then slough off or can be reabsorbed by the organism when the wound initiates the healing process. In this work, we intended to develop a new urethane‐based bioadhesive that could accomplish these purposes. Urethanes are considered to be promising candidates as adhesives because of the possibility of their synthesis as prepolymers and therefore their reaction with amino groups present in the biological molecules. Some urethanes were obtained by the reaction of poly(ethylene glycol) with isophorone diisocyanate. The characterization of the various materials was accomplished with different techniques: attenuated total reflection/Fourier transform infrared, swelling‐capacity determination, the evaluation of the moisture‐curing kinetics, a reaction with aminated substrates (as a simulation of the living tissues), and the determination of the surface energy by contact‐angle measurements. The study of the thermal properties of the urethanes was performed by dynamical mechanical thermal analysis, differential scanning calorimetry, and thermogravimetric analysis. The hemocompatibility of the urethane was also evaluated by thrombosis and hemolysis tests. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Biodegradable poly(vinyl alcohol)‐graft‐ poly(ε‐caprolactone) comb‐like polyester: Microwave synthesis and its characterization
Authors: Yu Zhaoju , Liu Lijian 
Published: March 2007

AbstractPoly(vinyl alcohol)‐initiated microwave‐assisted ring opening polymerization of ε‐caprolactone in bulk was investigated, and a series of poly(vinyl alcohol)‐graft‐poly(ε‐caprolactone) (PVA‐g‐PCL) copolymers were prepared, with the degree of polymerization (DP) of PCL side chains and the degree of substitution (DS) of PVA by PCL being in the range of 3–24 and 0.35–0.89, respectively. The resultant comb‐like PVA‐g‐PCL copolymers were confirmed by means of FTIR, 1H NMR, and viscometry measurement. The introduction of hydrophilic backbone resulted in the decrease in both melting point and crystallization property of the PVA‐g‐PCL copolymers comparing with linear PCL. With higher microwave power, the DP of PCL side chains and DS of PVA backbone were higher, and the polymerization reaction proceeded more rapidly. Both the DP and monomer conversion increased with irradiation time, while the DS increased first and then remained constant. With initiator in low concentration, the DP and DS were higher, while the monomer was converted more slowly. Microwaves dramatically improved the polymerization reaction in comparison of conventional heating method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3973–3979, 2007
An investigation on the reinforcing potential of red earth as filler for natural rubber compounds
Authors: Osabohien E. , Egboh S. H. O. 
Published: March 2007

AbstractLocally sourced red earth (RE) was air‐dried, pulverized, and screened with a sieve of mesh size 75 nm. It was characterized in terms of its moisture content, loss on ignition, silica content, iodine adsorption number, oil absorption, pH, and metal oxide compositions. Natural rubber, standard Nigerian rubber used for this work was first characterized in terms of its dirt, ash and nitrogen contents, volatile matter, plasticity retention index, and Mooney viscosity. The RE was applied as filler wholly and in blends with standard carbon black, CB (N330) filler in the natural rubber compounding using efficient vulcanization system. The cure and the physicomechanical properties of the compounds and vulcanizates were, respectively, measured as function of filler loading. The results were compared with those of the standard carbon black (N330)‐filled natural rubber. It was found, that the RE‐filled natural rubber showed substantial reinforcement of the rubber, though inferior to carbon black (N330) filled vulcanizates, the tensile strength of the carbon black‐filled vulcanizates is about one half times that of the RE‐filled vulcanizates. The tensile properties of the RE‐filled vulcanizates improved markedly by blending the RE‐filler with the carbon black (N330). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
HPLC determination of safflor yellow A and three active isoflavones from TCM Naodesheng in rat plasma and tissues and its application to pharmacokinetic studies
Authors: Yu Zhiguo , Gao Xiaoxia , Zhao Yunli , Bi Kaishun 
Published: March 2007

AbstractA high‐performance liquid chromatographic method was developed for the simultaneous determination and pharmacokinetic studies of safflor yellow A, puerarin, 3′‐methoxyl‐puerarin, and puerarinapioside in the plasma and tissues of rats that had been administered with the traditional Chinese medicine (TCM) preparation Naodesheng via the caudal vein. Samples taken from rats were subjected to protein precipitation with acetone. Separation of these four compounds was accomplished on a Kromisil C18 stationary phase using a mobile phase of acetonitrile–0.1% phosphoric acid–tetrahydrofuran (8:92:2, v/v/v) at a flow‐rate of 1.0 mL/min. The detection wavelength was set at 250 nm. The calibration curves of the four components were linear in the given concentration ranges. The intra‐ and inter‐day precisions in plasma and tissues were less than 15% and the extraction recoveries were higher than 60%. The lower limits of quantitation of four components were low enough to determine the four components. These four components all exhibited kinetics that fitted a two‐compartment model in rats. The elimination half‐life was 1.19 h for safflor yellow A, 2.69 h for puerarin, 2.94 h for 3′‐methoxyl‐puerarin, and 0.87 h for puerarinapioside, respectively. Following administration of a single injection of Naodesheng, the concentration (C) of the four components in the tissues showed Ckidney > Clung, Cliver > Cspleen, Cstomach, Cheart, approximately. The method is a reliable tool for performing studies of safflor yellow A and three puerarin isoflavones in different biological material. Copyright © 2007 John Wiley & Sons, Ltd.
An improved high‐performance liquid chromatographic method with a solid‐phase extraction for the determination of piperacillin and tazobactam: application to pharmacokinetic study of different dosage in Chinese healthy volunteers
Authors: Xia Chun‐hua , Xiong Yu‐qing , Wang Guang‐ji 
Published: March 2007

AbstractAn improved HPLC method was developed for the determination of piperacillin and tazobactam in human plasma and pharmacokinetic study in Chinese healthy volunteers. Piperacillin and tazobactam in human plasma were extracted by solid‐phase extraction and separated on a C18 column and detected at 220 nm. The mobile phase for piepracillin consisted of 0.01 mol/L sodium dihydrogen phosphate (pH = 4.65) and acetonitrile (71:29, v/v), and that for tazobactam was 0.05 mol/L sodium dihydrogen phosphate (pH = 4.45) and methanol (90:10, v/v). The method was linear in the range 0.25–320.00 µg/mL for piperacillin (r2 = 0.995) and 0.25–64.00 µg/mL for tazobactam (r2 = 0.994). The lower limit of quantification of both compounds was 0.25 µg/mL. The intra‐ and inter‐day precisions of piperacillin and tazobactam at three concentrations were all less than 9.2% and accuracies were within the range 97.0–108.0%. The method was used to investigate the pharmacokinetics of piperacillin and tazobactam in 12 volunteers who were intravenously given a dosage of 1.25, 2.50 and 3.75 g in three periods. The results showed that piperacillin sodium–tazobactom sodium (4:1) for injection in Chinese people fits linear dynamics, and the administred dosage can be adjusted with therapeutic effect. Copyright © 2007 John Wiley & Sons, Ltd.
Simultaneous determination of panax notoginsenoside R1, ginsenoside Rg1, Rd, Re and Rb1 in rat plasma by HPLC/ESI/MS: platform for the pharmacokinetic evaluation of total panax notoginsenoside, a typical kind of multiple constituent traditional Chinese medicine
Authors: Li Xiaoyu , Sun Jianguo , Wang Guangji , Hao Haiping , Liang Yan , Zheng Yuanting , Yan Bei , Sheng Longsheng 
Published: March 2007

AbstractA platform for the pharmacokinetic study of multiple constituent traditional Chinese medicine was developed and validated. An HPLC/ESI/MS method was employed for the simultaneous determination of panax notoginsenoside R1, ginsenoside Rg1, Rd, Re and Rb1 in rat plasma. After the addition of digoxin as an internal standard (IS), rat plasmas were extracted with n‐butanol saturated with pure water and all analytes were separated on a reversed‐phased C18 column with a mobile phase of acetonitrile–water (0.5 mm ammonium chloride) and pumped at a flow rate of 0.2 mL/min. Analytes were determined in a single quadrupole mass spectrometer using an electrospray ionization source. HPLC/ESI/MS was performed in the selected‐ion monitoring mode with the chlorinated adducts of molecular ions [M + Cl] − at m/z 967.75, 835.80, 981.80, 981.80, 1143.65 and 815.40 for R1, Rg1, Rd, Re, Rb1 and digoxin, respectively. The method showed excellent linearity over the concentration range 3.03–775.00 ng/mL (r2 = 0.9994) for R1, 4.00–1025.00 ng/mL (r2 = 0.9991, 0.9988, 0.9991) for Rg1, Rd and Re, respectively, and 2.77–710.00 ng/mL for Rb1 (r2 = 0.9990). The low limit of quantification was 3.03, 4.00, 4.00, 4.00 and 2.77 ng/mL for R1, Rg1, Rd, Re and Rb1, respectively, with S/N > 10. The intra‐ and inter‐day precisions were below 12.00% and the accuracy was between −2.31 and +4.43% for all analytes. The extract recoveries of analytes were from 67.47 to 94.18%. All analytes were stable in rat plasma after storage for 12 h at ambient temperature, at 4°C for 12 h in the sample pool, at −20°C for 4 weeks and at −20°C for three thaw–freeze cycles. The HPLC/ESI/MS technique provided an excellent method for the simultaneous quantification of R1, Rg1, Rd, Re and Rb1 in rat plasma and was successfully applied to the pharmacokinetic study of a multiple‐constituent traditional Chinese medicine, total panax notoginsenoside (Xuesaitong injection). Copyright © 2007 John Wiley & Sons, Ltd.
Determination of imatinib mesylate and its main metabolite (CGP74588) in human plasma and murine specimens by ion‐pairing reversed‐phase high‐performance liquid chromatography
Authors: Oostendorp Roos L. , Beijnen Jos H. , Schellens Jan H. M. , Tellingen Olaf van 
Published: March 2007

AbstractA sensitive reversed‐phase high‐performance liquid chromatographic (HPLC) method has been developed and validated for the determination of imatinib, a tyrosine kinase inhibitor, and its main metabolite N‐desmethyl‐imatinib (CGP74588) in human plasma and relevant murine biological matrices. A simple HPLC assay for the individual quantification of imatinib and CGP74588 in murine specimens has not been reported to date. Sample pre‐treatment involved liquid–liquid extraction with tert‐butyl‐methyl ether. Imatinib, CGP74588 (metabolite) and the internal standard 4‐hydroxybenzophenone were separated using a narrow bore (2.1 × 150 mm) stainless steel Symmetry C18 column and detected by UV at 265 nm. The mobile phase consisted of 28% (v/v) acetonitrile in 50 mm ammonium acetate buffer pH 6.8 containing 0.005 m 1‐octane sulfonic acid and was delivered at 0.2 mL/min. The calibration curve was prepared in blank human plasma and was linear over the dynamic range 10 ng/mL to 10 µg/mL). The accuracy was close to 100% and the within‐day and between‐day precisions were within the generally accepted 15% range. The validation results showed that the assay was selective and reproducible. This method was applied to study the pharmacokinetics of imatinib and its main metabolite in human and mice. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of calycosin‐7‐O‐β‐d‐glucopyranoside in rat plasma and urine by HPLC
Authors: Ye Guan , Ma Rong‐Rong , Li Zhi‐Xiong , Wang Hui , Zhu Hai‐Yan , Sun Zhao‐Lin , Huang Cheng‐Gang 
Published: March 2007

AbstractA reversed‐phase high‐performance liquid chromatographic (HPLC) assay for calycosin‐7‐O‐β‐d‐glucopyranoside in rat plasma and urine with solid‐phase extraction (SPE) was developed. Rutin was employed as an internal standard. The mobile phase consisted of acetonitrile–water (16:84, v/v) at a flow rate of 1.0 mL/min. Detection was set at 280 nm. The limit of quantitation of calycosin‐7‐O‐β‐d‐glucopyranoside was 0.2 µg/mL in both plasma and urine. The standard curve was linear from 0.2 to 10.0 µg/mL in plasma, and 0.2 to 5.0 µg/mL in urine. Both intra‐ and inter‐day precision of the calycosin‐7‐O‐β‐d‐glucopyranoside were determined and their RSD did not exceed 10%. The method was successfully applied to the analysis of samples obtained from a basic pharmacokinetic study, in which calycosin‐7‐O‐β‐d‐glucopyranoside was administered orally to rats. Copyright © 2007 John Wiley & Sons, Ltd.
Separating Y‐predictive and Y‐orthogonal variation in multi‐block spectral data
Authors: Eriksson Lennart , Toft Marianne , Johansson Erik , Wold Svante , Trygg Johan 
Published: March 2007

AbstractSpectral data (X) may contain (a) variation that is correlated to concentrations or properties (Y) of samples and (b) variation that is unrelated to the same Y. This paper outlines an approach by which both such sources of variation may be resolved. The approach is based on a combination of hierarchical modelling and orthogonal partial least squares (OPLS). OPLS is first used at the base hierarchical level. The output is a labelling of the resulting score vectors as representing Y‐predictive or Y‐orthogonal variation. OPLS is then also used at the top hierarchical level together with principal components analysis (PCA). With PCA the Y‐orthogonal X‐variation is analysed and interpreted. With OPLS the Y‐predictive X‐variation is examined. The applicability of the proposed strategy is illustrated using one multi‐block spectral data set. Copyright © 2007 John Wiley & Sons, Ltd.
Breaking Chemistry's Strongest Bond: Can Three‐Coordinate [M{N(R)Ar}3] Complexes Cleave Carbon Monoxide?
Authors: Christian Gemma , Stranger Robert , Petrie Simon , Yates Brian F. , Cummins Christopher C. 
Published: March 2007

AbstractThe reaction pathway for the interaction of CO with three‐coordinate TaIII, WIII and ReIII complexes (modelled on the experimental [M{N(tBu)Ar}3] system) has been explored by using density functional methods. Calculations show that CO binds without a barrier to [Re(NH2)3], forming the encounter complex [OCRe(NH2)3], which is stabilized by ≈280 kJ mol−1 relative to the reactants. The binding of [Ta(NH2)3] to the oxygen terminus of CO is inhibited by a barrier of only 20 kJ mol−1 and is followed by spontaneous cleavage of the CO bond to form the products [CRe(NH2)3] and [OTa(NH2)3]. The salient features of the potential energy surface are more favourable to CO cleavage than the analogous N2 cleavage by [Mo(NH2)3], which is less exothermic (335 vs. 467 kJ mol−1) and is impeded by a significant barrier (66 kJ mol−1). The ReIII/TaIII/CO system therefore appears to be an excellent candidate for cleaving the exceptionally strong CO bond under mild laboratory conditions. The related WIII/TaIII dimer, which significantly weakens but does not cleave the CO bond, may be a suitable alternative when the chemistry is to be performed on activated CO rather than on the strongly bound oxide and carbide cleavage products.
Industry–government interaction in the preparation of a new directive: Nokia, industry associations and EuP
Authors: Kautto Petrus 
Published: March 2007

AbstractThis article sheds light on the interaction between the European Commission and different stakeholders via an illustrative example, the preparation of a proposal for what is known as the EuP directive. The main aim is to inquire how a multinational Finnish corporation, Nokia, and related industry associations anticipated legislation under preparation and how they tried to influence the preparation process. Thus, it contributes to the discussion on the role of business in public policy. The paper is based on a combination of different data collection methods and it covers approximately the period from spring 2000 to July 2003. As a result, it highlights how industry associations, Nokia and some other major companies thoroughly reformulated the proposal using issue based strategies. Besides, it describes which venues Nokia selected for lobbying, and illustrates the dependency of the Commission on companies and interest groups as sources of information. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
Two New Flavonoids from Bonannia graeca: a DFT‐NMR Combined Approach in Solving Structures
Authors: Rosselli Sergio , Bruno Maurizio , Maggio Antonella , Bellone Gabriella , Formisano Carmen , Mattia Carlo Andrea , Di Micco Simone , Bifulco Giuseppe 
Published: March 2007

AbstractTwo new cyclized C‐geranylated flavonoids, the dihydroflavonol bonanniol C (4a) and the flavanone bonannione B (6a), were isolated as minor compounds from the aerial parts of Bonannia graeca (Umbelliferae). Their structures were elucidated by a combined approach of extensive spectroscopic means and quantum mechanical methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthetic and Mechanistic Investigations on the Rearrangement of 2,3‐Unsaturated 1,4‐Bis(alkylidene)carbenes to Enediynes
Authors: Sahu Bichismita , Muruganantham Rajendran , Namboothiri Irishi N. N. 
Published: March 2007

AbstractThe synthesis of 3,4‐ene‐1,5‐diynes, the key structural moiety present in several naturally occurring antitumor antibiotics, from 1,2‐enedialdehydes under two different experimental conditions is reported. One method involves the dibromomethylenation of dialdehydes under Corey–Fuchs conditions (CBr4, Ph3P, and Zn) and treatment of the resulting tetrabromides with nBuLi or LDA to afford enediynes. The second method involves a base‐mediated reaction of enedialdehydes with diethyl (1‐diazo‐2‐oxopropyl)phosphonate (Bestmann–Ohira reagent) and subsequent transformation of the bis(diazo) compounds generated in situ to enediynes. While the transformation of bis(diazo) compounds to enediynes could take place exclusively through alkylidenecarbenes, generated in situ by geminal elimination of N2, an alternative pathway, involving the vicinal elimination of HBr to afford an intermediate bromoalkyne and its subsequent metal‐halogen exchange and protonation during workup, exists for the bis(dibromoalkylidenes). However, our deuterium‐labeling experiments with a model substrate, deuterated p‐methoxybenzylidene dibromide, established the predominance of the alkylidenecarbenes, generated in situ by metal‐halogen exchange and elimination, for this substrate and, by analogy, for the tetrabromides as well. The scope of this novel methodology was extended to the synthesis of various heteroatom‐based (S, Se, and P) enediynes by quenching the acetylides with suitable electrophiles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Electrochemical Preparation of Poly(acriflavine) Film‐Modified Electrode and Its Electrolcatalytic Properties Towards NADH, Nitrite and Sulfur Oxoanions
Authors: Chen Shen‐Ming , Liu Meei‐Ing , Kumar S. Ashok 
Published: March 2007

AbstractElectrochemical polymerization of acriflavine (AF) was carried out onto glassy carbon electrodes (GCE) from the aqueous buffer solution containing 1.5×10−3 M AF monomer (pH 3.5) which produced a thin electrochemically active film. This is noted as poly(AF) film modified electrodes (PAF/GCE). This modified electrode was shown a stable reversible redox couple centered at +0.22 V in pH 3.5 buffer solutions. PAF/GCE was found to be more stable in acidic solutions and its formal potential was found to be pH dependent with a slope close to −60 mV/pH. The electrochemical deposition kinetics of poly(AF) onto gold coated quartz crystal was studied by using electrochemical quartz crystal microbalance (EQCM) combined with cyclic voltammetry (CV). PAF/GCE was found be good mediator for electrochemical oxidation of reduced nicotinamide adenine dinucleotide (NADH) in pH 5 buffer solutions. The electrocatalytic oxidation of SO$\rm{ _3^{2 - } }$ and electrocatalytic reduction of NO$\rm{ _2^ - }$, SO$\rm{ _5^{2 - } }$ and S2O$\rm{ _8^{2 - } }$ were carried out at PAF/GCE electrode in acidic aqueous solutions. The electrocatalytic oxidation of NADH was also investigated by using amperometric method.
Electrochemical Catalytic Processes with Hydrogen Peroxide Showing Oxidative and Reductive Properties (Acting as Oxidant or Reductant)
Authors: Pacześniak Tomasz , Błoniarz Paweł , Rydel Katarzyna , Sobkowiak Andrzej 
Published: March 2007

AbstractIt has been found that hydrogen peroxide can act as an oxidant and as a reductant of transition metal complexes in acetonitrile. Therefore, the examples of catalytic currents of oxidants and reductants has been described. In the case of Co(acac)3 both the types of catalytic currents are present in a single cyclic‐voltammetric scan.