bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, characterization, and swelling kinetics of pH‐responsive and temperature‐responsive carboxymethyl chitosan/polyacrylamide hydrogels
Authors: Wei Qing‐Bo , Luo Yan‐Ling , Fu Feng , Zhang Yu‐Qi , Ma Rong‐Xuan 
Published: December 2012

AbstractA novel pH‐ and temperature‐responsive hydrogel composed of carboxymethyl chitosan (CMC) and polyacrylamide (PAM) semi‐interpenetrating polymer networks (semi‐IPNs) was synthesized by a crosslinking copolymerization route in the presence of N,N‐methylene bisacrylamide and potassium persulfate. The structure of the CMC/PAM hydrogels was characterized by Fourier transform infrared spectroscopy, and the morphologies were observed by scanning electron microscopy. The swelling kinetics investigations demonstrated that the equilibrium swelling ratios (ESRs) of the semi‐IPN hydrogels depended on the compositional ratios, pH values of the buffer solutions, and temperature. The ESR values increased with increasing CMC contents and pH values; this was in agreement with the maximum theoretical water contents fitted by the swelling kinetic data. The CMC/PAM hydrogels complied with Fickian behavior at pH 1.4 and non‐Fickian behavior at pH 11.7 in the buffer solutions. These hydrogels displayed thermosensitivities that were different from those of common thermoresponsive gels. The swelling was enhanced when the temperature of the media was increased up to 40°C; this was followed by a reduction. Therefore, the swelling behavior of the CMC/PAM hydrogels could be controlled and modulated by means of the compositional ratios of CMC to acrylamide, pH values of the buffer solutions, and temperature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Formulation of pH‐responsive carboxymethyl chitosan and alginate beads for the oral delivery of insulin
Authors: Mukhopadhyay Piyasi , Sarkar Kishor , Soam Shweta , Kundu P. P. 
Published: December 2012

AbstractpH‐sensitive beads were prepared from the interpenetrating polymer networks (IPNs) of carboxymethyl chitosan (CMCTS) and alginate to study their application in oral insulin administration. CMCTS was synthesized from chitosan and was characterized by Fourier transform infrared spectroscopy and wide‐angle X‐ray diffraction. Calcium chloride, a relatively less toxic material, was used to crosslink both the alginate and CMCTS to prepare the IPN beads. The IPN beads were used to encapsulate insulin at different weight ratios. The swelling behavior and insulin release profile in response to simulated gastric and intestinal media of the beads were investigated. The beads observed under scanning electron microscopy were almost spherical, with an average diameter of 780 μm. The bead with about a 54% insulin loading efficiency was observed to contain about 98% encapsulated insulin. The maxima of about 20% insulin retention at acidic pH (1.2) and about 94% insulin release at intestinal pH (7.4) justified the good pH‐responsive nature of these IPN beads. Moreover, the insulin released from the IPN beads was stable and biologically active. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Possible tuning fabrication of nanoplatinum particles with the conducting copolymer films and their behavior toward the electrooxidation of methanol
Authors: Zhang Guirong , Ding Binbin , Wu Liang , He Li , Ni Bing , Lu Jiaxing 
Published: December 2012

AbstractThe electrocopolymerization of o‐toluidine (OT) and p‐phenylenediamine (PPDA) on a platinum electrode in a solution of 0.5 mol/dm3 H2SO4 with cyclic voltammetry was examined. The addition of PPDA to the solution of OT in 0.5 mol/dm3 H2SO4 accelerated the electrocopolymerization of OT and PPDA. Fourier transform infrared spectroscopy and ultraviolet–visible spectra for the polymers showed that the unit of PPDA should have been integrated into the backbones of the copolymers to form phenazine‐like ring structures, and the delocalization of electrons in the copolymer was better than that in poly(o‐toluidine) (POT). The scanning electron microscopy (SEM) images for the polymers showed that the copolymers became more porous, and smaller particles, which made oxygen, oxidized the reduced copolymer more easily and faster. It was proven with SEM, energy‐dispersive X‐ray spectroscopy, and transmission electron microscopy that the size of the nanoplatinum particles deposited on the copolymer reached 10 nm and was much smaller than those on POT. They had better tolerance to the poisoning species arising from the intermediates of the dissociation of methanol on a platinum electrode during the electrocatalytic oxidation of methanol. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Flame retardant polyurethane nanocomposite: Study of clay dispersion and its synergistic effect with dolomite
Authors: Amiri Rafieh‐Sadat Norouzian , Tirri Teija , Wilen Carl‐Eric 
Published: December 2012

AbstractPolyurethane–clay nanocomposite adhesives were prepared by different synthetic routes and their microstructures were determined by X‐ray diffraction measurements and from transmission electron microscopy images. The preparation method of the polyurethane nanocomposite adhesives was systematically changed, that is, condensation either in the presence or absence of catalyst, concentration and type of nanoclay, premixing order of nanoclay (nanoclay was either premixed with the polyol or isocyanate part) and by using MDI surface treated nanoclays. Depending on the polymerization conditions cluster, intercalated, and exfoliated clay structures were obtained. The flame retardant properties of the manufactured nanocomposite adhesives and the synergistic effect of clay in combination with dolomite were investigated by cone calorimeter and UL 94 vertical burning tests. The results indicate that addition of nanoclay reduces burning time and the total heat evolved (THE) at flame out, and that the type of assembled clay structure (cluster, intercalated or exfoliated) had a significant effect on the flame retardant property. Nanocomposites with 3 wt % of clay loading gave the shortest burning time, the lowest THE and also UL 94 V‐2 ratings were reached, although the flame retardancy in terms of heat release rate and time to ignition was not improved. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Polysulfone microcapsules with different wall morphology
Authors: Panisello Cinta , Peña Brisa , Gumí Tània , Garcia‐Valls Ricard 
Published: December 2012

AbstractFor the production of polysulfone microcapsules, a process was proposed, which allowed the obtaining of capsules with different wall morphology. A polysulfone solution was projected to a precipitation bath. Three solvents were assessed: N,N‐dimethylformamide, N,N‐dimethylacetamide, and N‐methyl‐2‐pyrrolidone. Precipitation baths were composed by water, pure or mixed with solvent. Surfaces and cross–sections of different preparations were observed by Scanning Electron Microscopy. The study was focused on capsules of 30 ± 10 µm of diameter. Microcapsules surfaces were porous and two different structures were distinguished in the cross‐section: macrovoids and sponge‐like structures. High concentration of solvent in the precipitation bath reduced the porosity of the surface and the macrovoids of the wall, thus favoring sponge‐like structures. The present work set some bases for a better control of polysulfone microcapsules morphology. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effects of the hydrophobization on chitosan–insulin nanoparticles obtained by an alkylation reaction on chitosan
Authors: Robles Emmanuel , Villar Eva , Alatorre‐Meda Manuel , Burboa María. G. , Valdez Miguel A. , Taboada Pablo , Mosquera Víctor 
Published: December 2012

AbstractIn this work, we investigate the influence of chitosan hydrophobization on the formation, physicochemical properties, solubilization, and release profiles of chitosan‐based nanoparticles (NPs) complexed with the protein insulin, used as a protein model. We use an alkylation procedure to insert 8, 10, and 12 carbon chains along the chitosan macromolecule with a final 5, 10, or 50% substitution degree. Nuclear magnetic resonance (NMR) and infrared spectroscopes (IR) were used to evaluate the success and extent of the hydrophobization procedure. The size, shape, and charge of bare polymer and polymer‐insulin NPs were evaluated by dynamic light scattering (DLS), transmission electron (TEM), and atomic force (AFM) microscopes, and zeta potential, respectively. DLS and zeta potential data demonstrated that polymeric NPs made with hydrophobized chitosans possess smaller sizes and higher positive charges than NPs obtained with unmodified chitosan. Also, TEM and AFM images showed that modified chitosan‐made NPs have more elongated structures. Isothermal titration calorimetry (ITC) was used to determine the type and extent of the existing interactions between the different constituting components of complexed insulin‐hydrophobized chitosan nanoparticles. The association efficiency and loading capacity of insulin into the polymeric nanoparticles were also investigated under different solution conditions. Our results showed that hydrophobized chitosan‐based NPs possess both higher association efficiencies and protein loading capacities at pH 6 in comparison with unmodified chitosan‐based ones. In vitro protein release studies at pH 5.3, 6, and 7.4 demonstrated that insulin is released more slowly from hydrophobized chitosan NPs, which would favor a more sustained protein release. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and Anticonvulsant Activity Evaluation of 5‐Phenyl‐[1,2,4]triazolo[4,3‐c]quinazolin‐3‐amines
Authors: Zheng Yan , Bian Ming , Deng Xian‐Qing , Wang Shi‐Ben , Quan Zhe‐Shan 
Published: December 2012

AbstractIn the present study we describe the syntheses and anticonvulsant activity evaluation of 5‐phenyl‐[1,2,4]triazolo[4,3‐c]quinazolin‐3‐amine derivatives. Their anticonvulsant activity and neurotoxicity were evaluated by the maximal electroshock seizure test (MES) and the rotarod test, respectively. The majority of the compounds prepared were effective in the MES screens at a dose level of 100 mg/kg. Of these compounds, the most promising was compound 8h, which showed an ED50 value of 27.4 mg/kg and a protective index (PI) value of 5.8. These values were superior to those provided by valproate (ED50 and PI values of 272 and 1.6, respectively) in the MES test in mice. As well as its anti‐MES efficacy, the potencies of compound 8h against seizures induced by pentylenetetrazole and thiosemicarbazide were also established, with the results suggesting that the GABAergic system‐mediated mechanisms might be involved in its anticonvulsant activity.
Traffic rationing and pricing in a linear monocentric city
Authors: Liu Wei , Yang Hai , Yin Yafeng 
Published: December 2012

SUMMARYThis paper presents a simple spatial equilibrium model for a linear monocentric city to investigate the effects of rationing and pricing on morning commuters' travel cost and modal choice behavior in each location. Under rationing and pricing, every day in the morning peak hour, each commuter is classified as either “free” or “rationed”. “Free” commuters are allowed to use the highway without paying the toll, whereas “rationed” commuters can avoid the toll only if they travel by transit. Each day, a fraction of commuters are rationed in their free use of the highway, and the rationing fractions are determined systematically so that everyone is equally rationed in a given period. It is found that Pareto‐improving rationing and pricing scheme might be obtained as a combination of the rationing degree and the toll associated with rationing. Extension to the rationing and pricing scheme with cordon and park‐and‐ride service has been made. Cordon and park‐and‐ride might help in improving the efficiency of rationing and pricing strategy although remains its Pareto‐improving property. Copyright © 2012 John Wiley & Sons, Ltd.
Fed‐batch cultivation of Escherichia coli expressed designer hepatitis C virus diagnostic intermediate and its evaluation
Authors: Gurramkonda Chandrasekhar , Talha Sheikh M. , Gudi Satheesh Kumar , Gogineni Venkateswara Rao , Surya Sambasiva Rao Krothapalli Raja 
Published: December 2012

AbstractThe present study aimed for an enhanced induction strategy combined with high‐level production of a capture antigen of hepatitis C virus (HCV) for use in diagnosis of HCV infection. We have expressed the synthetic gene encoding for HCV multiepitope protein in pET‐28a(+) vector and investigated its production in Escherichia coli BL21(DE3) cells using high‐cell‐density fed‐batch cultivation. A maximum cell dry mass of 30 g/L was obtained, and the culture was induced with 1, 5, and 10 mM isopropyl β‐d‐1‐thiogalactopyranoside (IPTG) for ∼4 H at 30°C; a maximum protein production of 1.5 g/L was observed in the case of induction with 10 mM IPTG. The enhanced induction strategy resulted in a ∼15‐fold increase as compared to 1 mM IPTG. The protein was purified using a simple immobilized metal affinity chromatography procedure, yielding 16.6 mg/g dry cell weight of pure protein with more than 99% purity. Further, the protein was evaluated for its diagnostic potential by using the commercially available HCV Seroconversion Panel, Worldwide HCV Performance Panel, and Viral Coinfection Panel. The protein showed high sensitivity and specificity, which was comparable to the best performing commercially available enzyme immunoassay (EIA) kits.
Characterization of pyrene biodegradation by white‐rot fungus Polyporus sp. S133
Authors: Hadibarata Tony , Kristanti Risky Ayu , Fulazzaky Mohamad Ali , Nugroho Agung Endro 
Published: December 2012

AbstractA white‐rot fungus of Polyporus sp. S133 was isolated from an oil‐polluted soil. The metabolism of pyrene by this fungus was investigated in liquid medium with 5 mg of the compound. Depletion of pyrene was evident during the 30‐day growth period and was 21% and 90%, respectively, in cometabolism and metabolism of pyrene alone. Pyrene was absorbed to fungal cells or biodegraded to form simpler structural compounds. Seventy‐one percent of eliminated pyrene was transformed by Polyporus sp. S133 into other compounds, whereas only 18% was absorbed in the fungal cell. The effects of pH and temperature on biomass production of Polyporus sp. S133 for pyrene were examined; the properties of laccase and 1,2‐dioxygenase produced by Polyporus sp. S133 during pyrene degradation were investigated. The optimal values of pH were 3, 5, and 4 for laccase, 1,2‐dioxygenase, and biomass production, respectively, whereas the optimal values of temperature were 25 °C for laccase and 50 °C for 1,2‐dioxygenase and biomass production. Under optimal conditions, pyrene was mainly metabolized to 1‐hydroxypyrene and gentisic acid. The structure of 1‐hydroxypyrene and gentisic acid was determined by gas chromatography–mass spectrometry after identification using thin‐layer chromatography.
Biosynthesis of silver nanoparticles using actinobacterium Streptomyces albogriseolus and its antibacterial activity
Authors: Samundeeswari Arputhamani , Dhas Sindhu Priya , Nirmala Joyce , John Shiny Punalur , Mukherjee Amitava , Chandrasekaran Natarajan 
Published: December 2012

AbstractAn eco‐friendly approach to the synthesis of silver nanoparticles (AgNPs) by extracellular components of Streptomyces albogriseolus has been reported. The isolated actinobacteria were genotypically identified by 16S rRNA sequencing analysis, and the morphology was observed by high‐resolution scanning electron microscopy. The preliminary characterization of synthesized nanoparticles was carried out using ultraviolet–visible spectrophotometer. The maximum absorption spectra were found to be 409 nm at the 48th hour of incubation. The yield of AgNPs was found to be 72.64% as quantified by an atomic absorption spectrophotometer. The average size of AgNPs determined by the dynamic light scattering technique was 16.25 ± 1.6 nm. The results from transmission electron microscopy and X‐ray diffraction confirmed the formation of spherical shaped and crystalline AgNPs. The interaction of protein with AgNPs was confirmed by Fourier transform infrared spectroscopy analysis. The biosynthesized AgNPs inhibited the growth of food pathogens (Bacillus cereus, Escherichia coli, and Staphylococcus aureus). Hence, the synthesis of AgNPs by S. albogriseolus could be employed as a probable antimicrobial agent to eliminate pathogenic microorganisms. This approach employed for the synthesis of nanoparticles paves a path for new biomaterial interfaces, which could be applied in different biomedical fields.
A new and simple resonance Rayleigh scattering method for human serum albumin using graphite oxide as probe
Authors: Wang Shengmian , Xu Lili , Wang Lisheng , Liang Aihui , Jiang Zhiliang 
Published: December 2012

ABSTRACTGraphite oxide (GO) was prepared by the Hummer procedure, and can be dispersed to stable colloid solution by ultrasonic wave. The GO exhibited an absorption peak at 313 nm, and a resonance Rayleigh scattering (RRS) peak at 490 nm. In pH 4.6 HAc‐NaAc buffer solution, human serum albumin (HSA) combined with GO probe to form large HSA‐GO particles that caused the RRS peak increasing at 490 nm. The increased RRS intensity was linear to HSA concentration in the range 0.50–200 µg/mL. Thus, a new and simple RRS method was proposed for the determination of HSA in samples, with a recovery of 98.1–104%. Copyright © 2012 John Wiley & Sons, Ltd.
A method of chemiluminescence coupled with ultrafiltration for investigating the interaction between ibuprofen and human serum albumin
Authors: Xiong Xunyu , Zhang Qunzheng , Nan Yefei , Gu Xuefan 
Published: December 2012

ABSTRACTIn acidic media, ibuprofen substantially enhanced the weak chemiluminescence (CL) produced by sodium sulfite and potassium permanganate. The increased signals were linearly correlated with ibuprofen concentrations ranging from 1.2 × 10‐3 to 4.8 μM, with a detection limit of 4.8 × 10‐4 μM. Two ultrafiltration (UF) membranes were used to construct a unit for trapping 0.15 and 0.75 μM human serum albumin (HSA) and coupled online with the CL system. At low HSA concentrations, the numbers of bound molecules per binding site were calculated to be 0.9 for Sudlow site I and 6.2 for Sudlow site II. The association constants on these binding sites were 5.9 × 105 and 3.4 × 104 M‐1, respectively. Our CL–UF protocol presents a rapid and sensitive method for studies on drug–protein interaction. Copyright © 2012 John Wiley & Sons, Ltd.
Formation of RNA Phosphodiester Bond by Histidine‐Containing Dipeptides
Authors: Wieczorek Rafał , Dörr Mark , Chotera Agata , Luisi Pier Luigi , Monnard Pierre‐Alain 
Published: December 2012

AbstractA new scenario for prebiotic formation of nucleic acid oligomers is presented. Peptide catalysis is applied to achieve condensation of activated RNA monomers into short RNA chains. As catalysts, L‐dipeptides containing a histidine residue, primarily Ser‐His, were used. Reactions were carried out in selforganised environment, a water‐ice eutectic phase, with low concentrations of reactants. Incubation periods up to 30 days resulted in the formation of short oligomers of RNA. During the oligomerisation, an active intermediate (dipeptide–mononucleotide) is produced, which is the reactive species. Details of the mechanism and kinetics, which were elucidated with a set of control experiments, further establish that the imidazole side chain of a histidine at the carboxyl end of the dipeptide plays a crucial role in the catalysis. These results suggest that this oligomerisation catalysis occurs by a transamination mechanism. Because peptides are much more likely products of spontaneous condensation than nucleotide chains, their potential as catalysts for the formation of RNA is interesting from the origin‐of‐life perspective. Finally, the formation of the dipeptide–mononucleotide intermediate and its significance for catalysis might also be viewed as the tell‐tale signs of a new example of organocatalysis.
The Role of π Bridges in High‐Efficiency DSCs Based on Unsymmetrical Squaraines
Authors: Delcamp Jared H. , Shi Yanrong , Yum Jun‐Ho , Sajoto Tissa , Dell'Orto Elisa , Barlow Stephen , Nazeeruddin Mohammad K. , Marder Seth R. , Grätzel Michael 
Published: December 2012

AbstractA series of squaraine‐based sensitizers with various π bridges and anchors were prepared and examined in dye‐sensitized solar cells. The carboxylic anchor group was attached onto a squaraine dye through π bridges with and without an ethynyl spacer. DFT studies indicate that the LUMO is delocalized throughout the dyes, whilst the HOMO resides on the squaraine core. The dye that incorporates a 4,4‐di‐n‐hexyl‐cyclopentadithiophene group that is directly attached onto the π bridge, JD10, exhibits the highest power conversion efficiency in a DSC; this result is attributed, in part, to the deaggregative properties that are associated with the gem‐di‐n‐hexyl substituents, which extend above and below the π‐conjugated dye plane. Dye JD10 demonstrates a power‐conversion efficiency of 7.3 % for liquid‐electrolyte dye‐sensitized solar cells and 7.9 % for cells that are co‐sensitized by another metal‐free dye, D35, which substantially exceed the performance of any previously tested squaraine sensitizer. A panchromatic incident‐photon‐to‐current‐conversion efficiency curve is realized for this dye with an excellent short‐circuit current of 18.0 mA cm−2. This current is higher than that seen for other squaraine dyes, partially owing to a high molar absorptivity of >5 000 M−1 cm−1 from 400 nm to the long‐wavelength onset of 724 nm for dye JD10.
Structure‐Dependent Electrocatalysis of Ni(OH)2 Hourglass‐like Nanostructures Towards L‐Histidine
Authors: Nai Jianwei , Chen Zhengbo , Li Haopeng , Li Fangyuan , Bai Yang , Li Lidong , Guo Lin 
Published: December 2012

AbstractAs the properties of nanomaterials are strongly dependent on their size, shape and nanostructures, probing the relations between macro‐properties and nanostructures is challenging for nanoscientists. Herein, we deliberately chose three types of Ni(OH)2 with hexagonal, truncated trigonal, and trigonal hourglass‐like nanostructures, respectively, as the electrode modifier to demonstrate the correlation between the nanostructures and their electrocatalytic performance towards L‐histidine. It was found that the hexagonal hourglass‐like Ni(OH)2 sample had the best electrocatalytic activity, which can be understood by a cooperative mechanism: on one hand, the hexagonal sample possesses the largest specific surface area and the tidiest nanostructure, resulting in the most orderly packing on the electrode surface; on the other hand, its internal structure with the most stacking faults would generate a lot of unstable protons, leading to an enhanced electronic conductivity. The findings are important because they provide a clue for materials design and engineering to meet a specific requirement for electrocatalysis of L‐histidine, possibly even for other biomolecules. In addition, the hexagonal Ni(OH)2‐based biosensor shows excellent sensitivity and selectivity in the determination of L‐histidine and offers a promising feature for the analytical application in real biological samples.