bluuebunny/crossref_metadata_2025_split huggingface dataset:
Styrene/phosphonic acid copolymers: Synthesis and thermal, mechanical, and electrochemical characterization
Authors: Santos L. E. P. , Hanamoto L. S. , Pereira R. P. , Rocco A. M. , Felisberti M. I. 
Published: July 2010

AbstractIn this study, a series of poly(styrene‐co‐vinyl phosphonic acid) [P(S‐co‐VPA)] copolymers were synthesized by the free‐radical copolymerization of styrene and vinyl dimethyl phosphonate followed by alkaline hydrolysis. The P(S‐co‐VPA) copolymers were characterized by size exclusion chromatography (gel permeation chromatography), Fourier transform infrared vibrational spectroscopy, proton nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and electrochemical impedance spectroscopy. Despite the difference between the copolymerization ratios of styrene and vinyl dimethyl phosphonate, the resulting copolymers presented single glass transitions at temperatures that depended on the acidic group amount. The glass transition shifted to a higher temperature and became broader as the amount of phosphonic acid increased. The storage modulus at temperatures higher than the glass transition also increased with increasing acidic groups because of intramolecular and intermolecular interactions. All of the acid copolymers were thermally stable to at least 300°C. A high oxidative stability was found for 3 : 1 P(S‐co‐VPA), which also presented conductivity values on the order of 10−6 Ω−1 cm−1 at room temperature. The 1 : 1 P(S‐co‐VPA) membrane presented Arrhenius‐type behavior at temperatures from 30 to 80°C and conductivity on the order of 10−5 Ω−1 cm−1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Aliphatic polyurethane–montmorillonite nanocomposite coatings: Preparation, characterization, and anticorrosive properties
Authors: Ashhari Shabnam , Sarabi Ali Asghar , Kasiriha Seyed Mahmoud , Zaarei Davood 
Published: July 2010

AbstractPolyurethane (PU)–clay nanocomposite coatings were prepared by a sonication method. The stability and morphology of these coatings was characterized by turbidometry, X‐ray diffraction, and transmission electron microscopy. The anticorrosive properties of these coatings were investigated by salt‐spray and electrochemical impedance spectroscopy methods. According to the results, dispersed nanoclay layers in the matrix of the nanocomposite coating compositions led to superior anticorrosive characteristics compared to those of pure PU coatings. The best results were obtained with coatings containing about 5 wt % clay. The resistance of the coating containing 5% clay was about 9.002 GΩ after 225 days of immersion in a 3.5 wt % NaCl solution, whereas it was only 97 kΩ for the pure PU coating. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A three‐function numerical model for the prediction of vulcanization‐reversion of rubber during sulfur curing
Authors: Milani G. , Milani F. 
Published: July 2010

AbstractThe cross‐linking mechanisms of sulfur vulcanization are not analytically known and, therefore, reticulation kinetics has to be deduced macroscopically from standardized tests. One of the most popular laboratory test to characterize curing and reversion is the oscillating disk rheometer ODR, which gives a quantitative assessment of scorch, cure rate, and state of cure. In this article, a numerical two‐step approach, which is based on the utilization of experimental ODR data and aimed at predicting the degree of vulcanization of thick rubber items cured with accelerated sulfur, is presented. In step one, a composite numerical three‐function curve is used to fit experimental rheometer data, able to describe the increases of the viscosity at successive curing times and at different controlled temperatures, requiring only few points of the experimental cure curve to predict the global behavior. Both the case of indefinite increase of the torque and reversion can be reproduced with the model. In step two, considering the same rubber compound of step one, numerical cure curves at different temperatures are collected in a database and successively implemented in a Finite Element software, which is specifically developed to perform thermal analyzes on complex 2D/3D geometries. As an example, an extruded thick EPDM section is considered and meshed through eight‐noded isoparametric plane elements. Several FEM simulations are repeated by changing exposition time tc and external curing temperature Tn, to evaluate for each (tc,Tn) couple the corresponding mechanical properties of the item at the end of the thermal treatment. A recently presented bisectional approach, alternating tangent (AT), is used to drastically reduce the computational efforts required to converge to the optimal solution associated with the maximum value of an output property, tensile strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Removal of phosphate by using copper‐loaded poly(N‐vinylimidazole) hydrogels as polymeric ligand exchanger
Authors: Özmen Fulya , Kavaklı Pınar Akkaş , Güven Olgun 
Published: July 2010

AbstractPolymeric ligand exchangers (PLE) are generally composed of a crosslinked hosting resin that can firmly hold a transition metal ion which can act as terminal functional groups. In this study, poly(N‐vinylimidazole) (PVIm) hydrogels were synthesized by free radical polymerization/crosslinking of N‐vinylimidazole in aqueous solution. Swelling behavior of PVIm hydrogels was investigated and the gel with minimum amount of crosslinking agent, hence showing maximum swelling was selected as the optimum gel system for further studies. To prepare the corresponding PLE for the removal of phosphate, PVIm hydrogels were loaded with Cu(II) ions. Copper loading capacity of PLE was determined to be 5 mmol of Cu(II)/g of dry gel. For removal of phosphate, adsorption experiments were performed in batch mode at different pH (3–9) and phosphate concentrations. It was found that phosphate adsorption capacity did not change significantly within this pH range. The effect of initial concentration of phosphate on the adsorption behavior of PLE was determined for 10 different phosphate concentrations (0.1–1000 mg/L) at pH 7. NaCl solution was used for regeneration of phosphate adsorbed Cu(II) loaded PVIm hydrogels with 100% regeneration efficiency. The new PLE showed high affinity for phosphate; the highest uptake was found to be 218 mg/g dry PLE from 1000 mg/L phosphate solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Metabolomic profiling can differentiate between bactericidal effects of free and polymer bound halogen
Authors: Ahmed Abd El‐Shafey I. , Wardell John N. , Thumser Alfred E. , Avignone‐Rossa Claudio A. , Cavalli Gabriel , Hay John N. , Bushell Michael E. 
Published: July 2010

AbstractThe effects of two halogenated compounds (sodium hypochlorite and N‐halamine polymers) on the Escherichia coli metabolome were investigated. Changes in the intracellular metabolite pools of bacterial cells treated with different formulations of these compounds were analysed using FTIR (Fourier Transform Infra Red) spectroscopy and LC‐MS (Liquid Chromatography‐Mass Spectroscopy). Principal component analysis was used to generate metabolic profiles of the intracellular metabolites to investigate the effect of sublethal concentrations on the metabolome of treated cells. The effect of treatment with sodium hypochlorite was quantitatively dependent on the exposure time. The resulting metabolic profiles supported our previous hypothesis that the mode of action of some halogenated compounds, such as N‐halamine polymers, can be initiated by release of halogen ions into the aqueous environment, in addition to direct contact between the solid polymer material and the bacterial cells. Moreover, the metabolic profiles were able to differentiate between the effect of free and polymer‐bound halogen. Our metabolomic approach was used for hypothesis generation to distinguish apparently different bactericidal effects of free and polymer‐bound halogen. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Characterization, mechanical, and thermal properties of gamma irradiated starch films reinforced with mineral clay
Authors: Ibrahim Sayeda M. 
Published: July 2010

AbstractComposite fabricated from starch and different concentrations of clay was prepared by solution casting method. The casted film was irradiated to different gamma irradiation doses 10, 20, 30, and 40 kGy. The dispersion of clay into starch was investigated by using X‐ray diffraction (XRD). The structural morphology of the composite was measured by scanning electron microscope and infrared spectroscopy. Film properties, such as water vapor transmission, mechanical, and thermal properties were also measured. The gel content and swelling behavior of the starch/clay composite were investigated. It was found that the gel content increases with increasing clay content and irradiation dose. The results obtained indicate that the starch/clay composite showed an increase in the tensile strength, thermal stability. Moreover, there is a decrease in water vapor transmission (WVRT) which improves its barrier properties. Both XRD and infrared spectroscopy showed that starch can be intercalated into the clay galleries. Also antibiotic drug Chlortetracycline HCl was loaded into the starch/clay composite by direct adsorption method. Chlortetracycline HCl adsorption capacity of composite was found to increase from 1.13 to 4.20 mg Chlortetracycline HCl per gram dry film with increasing amount of drug concentration. In vitro drug release studies in different buffer solutions showed that the basic parameters affecting the drug release behavior of the film are pH of the solution, drug concentration, and time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Adsorption behavior of monomers and formation of conducting polymers on polyester fibers
Authors: Zhao Yaping , Cai Zaisheng , Zhou Zhaoyi , Fu Xiaolan 
Published: July 2010

AbstractIn situ adsorption of monomers on fibers plays a key role in fabricating highly conductive polyaniline (PANI)‐based textiles by two‐stage oxidation polymerization. Experiments were conducted in aniline monomer and hydrochloric acid solution with the variables such as contact time, initial concentration, and temperature, which can enhance the equilibrium adsorption capacity to aniline of poly(ethylene terephthalate) (PET) fibers. Equilibrium data were fit well by a Henry partition‐type isotherm equation. It was found that the kinetics of the adsorption of aniline onto PET fibers at different operating conditions was best described by the pseudo‐second‐order model. The rate parameters of the intraparticle diffusion model for adsorption were also evaluated and compared to identify the adsorption mechanisms. The monomer exhaustion increased with increasing the temperature. The value of electrical surface resistance of conductive textiles about 3.2 kΩ was obtained when the padder squeeze step was introduced, and the molar ratio of 0.6 between the oxidant concentration and the exhausted concentration of monomers at the adsorption equilibrium was applied. Scanning electron micrographs of PANI/PET composite surfaces were observed, conforming that smooth films were produced by surface polymerization of aniline monomers adsorbed previously on fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Coating films prepared by photoreactions of the surface‐modified diamond powder and PET film with a binder agent
Authors: Hsu Ying‐Gev , Su Xing‐Wei , Lin Kuan‐Hung , Wan Yen‐Shen , Chen Jhih‐Cheng , Guu Jan‐An , Tsai Pi‐Chen 
Published: July 2010

AbstractThe surface‐modified diamond and PET film underwent photopolymerization rapidly with a binder agent to afford coating films of interpenetrating network (IPN) structure. The coating films thus formed exhibit higher tensile strength, thermal stability, and adhesion strength to the PET film. The inert surfaces of pristine diamond (PD) and PET film were modified by different chemicals and procedures to introduce epoxide and methacryloyl groups, respectively, on their surfaces. A coating agent consisting of an epoxide group containing modified diamond (called ED), a binder agent, and photoinitiators was prepared. After applying the coating agent to the substrate (a glass plate or a methacryloyl group containing PET film, MMA‐PET) and degassing under reduced pressure, the thin film of the coating agent was exposed to UV light (λmax; 365 nm) at room temperature to yield a coating film of IPN‐structure. The tensile strength and thermal properties of the ED‐containing free coating film (called free film) increased with the amount of ED embedded, whereas the strength of the PD‐containing free film decreased with the amount of PD embedded. The adhesion strength of the coating film on the MMA‐PET improved significantly by the free radical polymerization of the methacryloyl groups on the MMA‐PET and the acrylate resin in the binder agent. The surface photoreactions of ED and MMA‐PET with the binder agent were confirmed by modeling. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Stereology‐based quantitative characterization of dispersion from TEM micrographs of polymer–clay nanocomposites
Authors: Basu Soumendra K. , Fasulo Paula D. , Rodgers William R. 
Published: July 2010

AbstractQuantitative characterization of the state of dispersion and extent of exfoliation is critical in developing processing structure–property relationships in polymer–clay nanocomposites. Quantification of dispersion, exfoliation, and nanostructure in polymer–clay nanocomposites by 3D stereological parameters using image analysis of 2D transmission electron microscopy (TEM) micrographs were recently proposed. The 3D dispersion quantifying parameters are designed such that they are free of the bias associated with not sampling the true particle diameter in a 2D TEM section. In this article, the ability of the proposed 3D dispersion quantifying parameters to describe the dispersion over the entire possible range of exfoliation, and to capture independent aspects of dispersion are demonstrated by quantifying several sets of samples that were designed using a polypropylene (PP)/maleated PP/clay system. The details of the image analysis procedure, the underlying challenges, and errors involved in the segmentation process are also discussed. The 3D dispersion quantifying parameters, exfoliation number and inter‐particle distance, were critically compared against the standard 2D dispersion quantifying parameters, such as mean length, thickness, and aspect ratio. In all cases examined in this study, the sensitivity and resolution of the 3D parameters in terms of quantifying the dispersion of the nanostructure appeared comparable if not better than the standard 2D parameters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Application of reactive solvents of melamine for synthesis of polyetherols with perhydro‐1,3,5‐triazine rings
Authors: Wilk Klaudia , Lubczak Jacek 
Published: July 2010

AbstractThe application of reactive solvents (RSs), namely hydroxymethyl derivatives of acetone for digestion of isocyanuric acid, which is insoluble in most organic solvents except for DMSO, makes the substrate available for further conversions. At this step, the incorporation of perhydro‐1,3,5‐triazine ring into RS takes place. The obtained solutions were used for synthesis of polyetherols containing perhydro‐1,3,5‐triazine rings in reaction with oxiranes: ethylene and propylene oxides. The polyetherols were then used to obtain foamed polyurethanes with enhanced thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Viscosity‐molecular weight relationship for cellulose solutions in either NMMO monohydrate or cuen
Authors: Eckelt John , Knopf Anja , Röder Thomas , Weber Hedda K. , Sixta Herbert , Wolf Bernhard A. 
Published: July 2010

AbstractThe intrinsic viscosities, [η], of nine cellulose samples, with molar masses from 50 × 103 to 1 390 × 103 were determined in the solvents NMMO*H2O (N‐methyl morpholin N‐oxide hydrate) at 80°C and in cuen (copper II‐ethlenediamine) at 25°C. The evaluation of these results with respect to the Kuhn–Mark–Houwink relations shows that the data for NMMO*H2O fall on the usual straight line in the double logarithmic plots only for M ≤ 158 103; the corresponding [η]/M relation reads log ([η]/mL g−1) = –1.465 + 0.735 log M. Beyond that molar mass [η] remains almost constant up to M ≈ 106 and increases again thereafter. In contrast to NMMO*H2O the cellulose solutions in cuen behave normal and the Kuhn–Mark–Houwink relation reads log ([η]/mL g−1) = −1.185 + 0.735 log M. Possible reasons for the dissimilarities of the behavior of cellulose in these two solvents are being discussed. The comparison of three different methods for the determination of [η] from viscosity measurements at different polymer concentrations, c, demonstrates the advantages of plotting the natural logarithm of the relative viscosities as a function of c. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Doxorubicin loading and in vitro release from poly(alkylcyanoacrylate) nanoparticles produced by redox radical emulsion polymerization
Authors: Alhareth Khairallah , Vauthier Christine , Gueutin Claire , Ponchel Gilles , Moussa Fathi 
Published: July 2010

AbstractThe aim of this work was to explore the capacity to load an anticancer agent Doxorubicin (Dox) on new poly(alkylcyanoacrylate) (PACA) nanoparticles prepared by redox radical emulsion polymerization (RREP). These nanoparticles present several advantages compared with the previously described PACA nanoparticles obtained by anionic emulsion polymerization (AEP). Their cytotoxicity was lower and because they do not activate the complement system, they are believed to behave like stealth nanoparticles after intravenous administration. Dox was incorporated during the preparation of the nanoparticles. However, the drug molecules were degraded by cerium IV, which is a strong oxidant agent. To avoid drug degradation, Dox must be loaded by adsorption on preformed nanoparticles. Optimal loading capacity was deduced from a Scatchard's analysis of the Dox adsorption pattern. The loading performance [Loading efficiency (LE) 74%, Loading content (LC) 3.7%], the Dox release and the amount of Dox retained by the new nanoparticles 75% were similar to those of the already well described PACA nanoparticles obtained by AEP (LE 79% and LC 4.2%, drug retention capacity 75%). It can be concluded that the loading and releasing properties make the new nanoparticles an interesting carrier candidate for the in vivo delivery of Dox. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Peptide‐labeled supramolecular aggregates as selective doxorubicin carriers for delivery to tumor cells
Authors: Morisco Anna , Accardo Antonella , Tesauro Diego , Palumbo Rosanna , Benedetti Ettore , Morelli Giancarlo 
Published: July 2010

AbstractNew liposomal aggregates, prepared by combining together, in a 90:10 molar ratio, two amphiphilic monomers, one containing two hydrocarbon chains in the hydrophobic region and the anionic DOTA chelating agent as hydrophilic moiety, and the other containing the same hydrophobic moiety and the CCK8 peptide, are described. The liposomal aggregates because of the presence of the specific moiety, constituted by the CCK8 peptide, which selectively recognizes CCK receptors on tumor cells are used as drug carriers with the aim to deliver into tumor cells the appropriate antitumor drug. The drug loading content and the releasing properties of the liposomal aggregates are studied by the use of the cytotoxic doxorubicin as drug model. The doxorubicin loading content determination reveals that above 95% of the total drug was uptaken with a corresponding drug/lipid w/w ratio of 0.134. The cellular uptake of the targeted liposomal doxorubicin with respect to the self‐assembled, nonspecific, liposomal doxorubicin is evaluated using flow cytometry assays. The doxorubicin cell content for two types of cell systems, namely, A431 and HuVEC cells, for peptide derivatized liposomes was 70‐ and 8‐fold higher, respectively, than for nontargeted liposomes, indicating that the bioactive CCK8 peptide is able to enhance the doxorubicin uptake into the carcinoma cells in vitro. The cytotoxicity effect of liposomal doxorubicin on A431 cells has been assessed by MTT assays: in presence of drug amounts ranged between 250 and 1000 ng/ml, incubation with peptide derivatized liposomes showed significantly lower cell survival compared with nontargeted liposomes. © 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 88–96, 2011.
Influence of Cleavage Site on Global Folding of an RNA‐Cleaving DNAzyme
Authors: Lam Jeffrey C. F. , Li Yingfu 
Published: July 2010

Abstract8–17 is a DNAzyme with metal‐dependent endoribonuclease activity. Recently, a variant termed 8–17NG was reported as the first nucleic acid enzyme capable of cleaving all 16 dinucleotide junctions of RNA with rate enhancements ranging from 1000‐ to 1 000 000 000‐fold over background activity. We attributed this broad‐ranging cleavage efficiency to global folding of the DNAzyme. We sought to examine the influence of dinucleotides at the cleavage site of 8–17NG on global folding by using three‐color (3c) FRET. By comparing the folding of 8–17NG with all 16 possible dinucleotide junctions, we found all examined DNAzyme–substrate constructs adopted a two‐step folding process in the presence of Mn2+, which was consistent with previous metal‐induced folding studies of 8–17. Interestingly, Mn2+ titration experiments also suggest that the second folding step is dependent on dinucleotide identity: purine–purine junctions allowed 8–17NG to fold at lower concentrations than pyrimidine–pyrimidine linkages. This finding was corroborated by RNA cleavage assays, in which the largest improvement in cleavage yield was observed in pyrimidine–pyrimidine junctions when [Mn2+] was increased. Taken together, these results support the previously observed hierarchy of 8–17 activity for different cleavage sites. Complemented by earlier sequence and structure–function studies, this investigation allowed for the first detailed examination of crucial relationships between the structural influence and junction preferences of nucleic acid‐catalyzed RNA cleavage reactions.
Pacidamycin Biosynthesis: Identification and Heterologous Expression of the First Uridyl Peptide Antibiotic Gene Cluster
Authors: Rackham Emma J. , Grüschow Sabine , Ragab Amany E. , Dickens Shilo , Goss Rebecca J. M. 
Published: July 2010

AbstractThe pacidamycins are antimicrobial nucleoside antibiotics produced by Streptomyces coeruleorubidus that inhibit translocase I, an essential bacterial enzyme yet to be clinically targeted. The novel pacidamycin scaffold is composed of a pseudopeptide backbone linked by a unique exocyclic enamide to an atypical 3′‐deoxyuridine nucleoside. In addition, the peptidyl chain undergoes a double inversion caused by the incorporation of a diamino acid residue and a rare internal ureido moiety. The pacidamycin gene cluster was identified and sequenced, thereby providing the first example of a biosynthetic cluster for a member of the uridyl peptide family of antibiotics. Analysis of the 22 ORFs provided an insight into the biosynthesis of the unique structural features of the pacidamycins. Heterologous expression in Streptomyces lividans resulted in the production of pacidamycin D and the newly identified pacidamycin S, thus confirming the identity of the pacidamycin biosynthetic gene cluster. Identification of this cluster will enable the generation of new uridyl peptide antibiotics through combinatorial biosynthesis. The concise cluster will provide a useful model system through which to gain a fundamental understanding of the way in which nonribosomal peptide synthetases interact.