bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanochemical preparation of devulcanized ground fluoroelastomers for the enhancement of the thermal stability of nitrile–butadiene rubber vulcanizates
Authors: Lu Zhixing , Zhang Xinxing , Tian Dong , Li Hua , Lu Canhui 
Published: May 2012

AbstractMechanochemically devulcanized ground fluoroelastomer (FKM) was used as a low‐cost functional additive for the enhancement of the thermal stability of nitrile–butadiene rubber (NBR) vulcanizates. Without the use of any chemicals, the stress‐induced mechanochemical devulcanization of ground FKM was achieved through solid‐state mechanochemical milling at ambient temperature. The sol fraction of the ground FKM was increased from its original 1.4 to 19.8% after milling; this confirmed the realization of the mechanochemical devulcanization of FKM. Moreover, the oxygen‐containing polar groups on the surface of the mechanochemically milled FKM benefitted its interfacial adhesion with the polar NBR matrix. The curing characteristics and mechanical properties of the devulcanized, FKM‐filled NBR vulcanizates were investigated and compared with those of the untreated FKM‐filled NBR vulcanizates. The results show that the mechanical properties of the devulcanized FKM‐filled NBR vulcanizates were much better than those of the untreated FKM‐filled NBR vulcanizates. The presence of the reclaimed FKM significantly increased the onset degradation temperature of the NBR vulcanizates as a result of the improved polymer–filler interaction, uniform dispersion, and high thermal stability of the reclaimed FKM. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The nanocomposites of zinc oxide/L‐amino acid‐based chiral poly(ester‐imide) via an ultrasonic route: Synthesis, characterization, and thermal properties
Authors: Mallakpour Shadpour , Zeraatpisheh Fatemeh 
Published: May 2012

AbstractIn this investigation, a chiral poly) ester‐imide) (PEI) via direct polyesterification of N,N′‐(pyromellitoyl)‐bis‐(L‐tyrosine dimethyl ester) and N‐trimellitylimido‐L‐methionine was prepared using the tosyl chloride/pyridine/N,N′‐dimethylformamide system as a condensing agent. This approach allows the insertion of two natural amino acids into the polymer backbone and the creation of a bioactive polymer. From the chemical point of view, the ester groups impart to the polymer's main and side chain increased sensibility to hydrolysis that can cause chain breaking. Therefore, this polymer is expected to be biodegradable and could be classified as an eco‐friendly polymer. The polymer also had a useful level of thermal stability associated with excellent solubility. PEI/zinc oxide bionanocomposites were subsequently prepared by an ultrasonic method as a simple and inexpensive route, using ZnO nanoparticles (ZnO‐NPs) modified by 3‐aminopropyltriethoxylsilane (KH550) as a coupling agent. The structure and properties of the obtained BNC polymers were confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The direct proofs for the formation of the true BNC polymers were provided by TEM. Also, the morphology study of the synthesized polymer‐based BNCs showed well‐dispersed ZnO‐NPs in the polymer matrix by FE‐SEM analysis. TGA studies indicated that an increase of the NP content led to an enhancement of the thermal stability of the new BNC polymers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Study on molding process of UHMWPE microporous filter materials
Authors: Zhang Qiang , Jia Mingyin , Xue Ping 
Published: May 2012

AbstractA method called loose sintering was first introduced to prepare ultrahigh‐molecular weight polyethylene (UHMWPE) microporous materials. The pore size was predicted by the face‐centered cubic structure model while considering the particles' arrangement and melt. The results showed that the experimental pore diameter was close to that calculated by the present model. The effects of UHMWPE molecular weight, particle diameter, packing density, sintering temperature, and sintering time on pore size, compressive strength, pore diameter distribution, and density were presented. The morphology of micropore and the uniformity of pore distribution were analyzed by scanning electron microscopy and fractal geometry. The results showed that average pore diameter and porosity both increased with the UHMWPE particle diameter while decreased with compressive strength and bulk density. Sintering temperature and sintering time determined whether the heat was redundant to melt the particles. They also determined the pore size and the uniformity. UHMWPE microporous materials could be successfully prepared with suitable processing conditions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Molecular network development and evolution of nanoscale morphology in an epoxy‐amine thermoset polymer
Authors: Sahagun Christopher M. , Knauer Katrina M. , Morgan Sarah E. 
Published: May 2012

AbstractEpoxy‐amine thermoset polymers exhibit a complicated, highly crosslinked network structure. The connectivity of this network drives material parameters such as mechanical properties and solvent permeation. Understanding the molecular network architecture is also an important aspect of the developing realistic network topologies for use in molecular dynamic simulations. Here, the evolution of network connectivity in a typical crosslinked epoxy‐amine network (Epon 828/3‐aminophenyl sulfone) is monitored as a function of cure time. Special attention is paid to nanoscale variation in the crosslink density of the network. Submicron atomic force microscope images of sample fracture surfaces revealed three distinct types of crack tip propagation. Near‐infrared spectroscopy, rheological and thermal characterization were used to correlate each type of fracture propagation behavior to a different stage of network development. Monitoring changes in the nanoscale fracture behavior reveals information regarding changes in the network architecture during cure and provides insight into the final structure of the epoxy‐amine network. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Dynamic mechanical properties for polyurethane elastomers applied in elastomeric mortar
Authors: Rocco José Atílio Fritz Fidel , Lima José Eduardo Salgueiro , Lourenço Vera Lúcia , Batista Natássia Lona , Botelho Edson Cocchieri , Iha Koshun 
Published: May 2012

AbstractDynamic mechanical properties of a polyurethane (PU) elastomer and a mortar processed with the same elastomer (modified polytetramethylene ether glycol (PTMEG)) were studied. The results obtained showed that the liquid aromatic amine ETHACURE® 300, used as cure agent, can be used to substitute the aromatic amine MOCA®, which is usually used as cure agent in high performance elastomers. The resulting mortar produced with ETHACURE® 300 presents similar dynamic‐mechanical thermal properties when compared with MOCA ®. However, dynamic‐mechanical thermal analysis studies showed that the mortar developed with ETHACURE® 300 presents some advantages such as the low values of tan δ, indicating a good capacity of recovery of the strain after retreating an applied force. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Monodisperse‐porous N‐methyl‐D‐glucamine functionalized poly(vinylbenzyl chloride‐co‐divinylbenzene) beads as boron selective sorbent
Authors: Samatya Saba , Kabay Nalan , Tuncel Ali 
Published: May 2012

AbstractTo generate a new sorbent with high boron adsorption capacity, we synthesized monodisperse‐porous poly(vinylbenzyl chloride‐co‐divinylbenzene), poly(VBC‐co‐DVB), beads 8.5 μm in size by a new “modified seeded polymerization” technique. By using their chloromethyl functionality, the beads were derivatized by a simple, direct reaction with a boron‐selective ligand, N‐methyl‐D‐glucamine (NMDG). The selection of poly(VBC‐co‐DVB) beads as a starting material allowed to obtain high boron sensitive‐ligand density on the beads depending on their high chloromethyl content. In the batch adsorption runs performed using NMDG‐attached poly(VBC‐co‐DVB) beads as sorbent, boron removal was efficiently performed in a wide pH range between 4 and 11. Quantitative boron removal was observed with the sorbent concentration of 4 g/L. In the same runs, plateau value of equilibrium adsorption isotherm was obtained as 14 mg boron/g beads. Relatively higher boron adsorption was explained by high ligand density and high specific surface area of the sorbent. Boron adsorption isotherms were analyzed using Langmuir and Freundlich models. In the kinetic runs performed for boron removal, the equilibrium was attained within 10 min at a value of 98%. The fast kinetic behavior was explained by the smaller particle size and enhanced porosity of the new sorbent. Infinite solution volume model and unreacted core model were used to evaluate boron adsorption onto the NMDG‐attached poly(VBC‐co‐DVB) beads. The results indicated that the adsorption process is controlled by the particle‐diffusion step. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Characterization of polyvinyl chloride/polyethyl methacrylate polymer blend for use as polymer host in polymer electrolytes
Authors: Zakaria N. A. , Isa M. I. N. , Mohamed N. S. , Subban R. H. Y. 
Published: May 2012

AbstractPolyvinyl chloride (PVC) and polyethyl methacrylate (PEMA) were used to prepare polymer blends for use in solid polymer electrolyte. Dynamic mechanical analysis showed that both the storage modulus (E') and the glass transition temperature (Tg) of the PVC/PEMA blend are intermediate between those of the two component polymers. Scanning electron microscopy proved that addition of PEMA into PVC changed the morphology of the blends. The shifts in Fourier transform infrared bands and X‐ray diffraction peaks together with the presence of a single Tg suggest that the blends are partially miscible. The blend with 35 wt % PEMA seems to be the most suitable candidate for use as polymer host in polymer electrolyte, because it has the most suitable mechanical property and is the most amorphous blend system. This blend system also has the highest room temperature conductivity value of 4.74 × 10−10 S cm−1 amongst other blend systems. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigating the self healing process on coated steel by SVET and EIS techniques
Authors: Neema S. , Selvaraj M. , Raguraman J. , Ramu S. 
Published: May 2012

AbstractMicroencapsule was incorporated into an interpenetrating polymer network and applied over steel surface. A scratch was made on the coated surface and its self healing ability was studied using scanning vibrating electrode technique (SVET) and electrochemical impedance spectroscopy (EIS). Results of SVET studies show that the current density increases in the initial stage. After 24 h, the current density decreases, which indicating the formation of passive polymer film due to the diffusion of core polymer present in the microcapsules through the holidays. Increase in the resistance (107 Ω/cm2) of the self healing coating was observed after 24 h in EIS studies confirming the formation of the passive film. The results of the studies are discussed in this article. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Microstructural characterization of corn starch‐based porous thermoplastic composites filled with multiwalled carbon nanotubes
Authors: Yurdakul Hilmi , Durukan Oya , Seyhan A. Tugrul , Celebi Hande , Oksuzoglu Mustafa , Turan Servet 
Published: May 2012

AbstractMicrostructural characterization of corn starch‐based porous thermoplastic (TPS) composites containing various contents (0.1, 0.5, and 1 wt %) of multiwalled carbon nanotubes (MWCNTs) was performed. Corn starch was plasticized with a proper combination of glycerol and stearic acid. TPS composites with MWCNT were prepared conducting melt extrusion followed by injection molding. TPS containing 1 wt % of MWCNTs exhibited higher tensile strength and elastic modulus values than neat TPS. Moreover, TPS electrical conductivity was determined to increase with increasing content of MWCNTs. X‐ray diffraction measurements revealed that incorporation of MWCNTs increased the degree of TPS crsystallinity to some extent. Scanning electron microscopy examination revealed that MWCNT altered TPS surface morphology and tensile failure modes, significantly. Transmission electron microscopy investigation showed that dispersion characteristics of MWCNTs within TPS were in the form of tiny clusters around micro pores of TPS, which is considered influential on electrical conductivity of the resulting composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Grafting of poly(vinyl alcohol) on natural rubber latex particles
Authors: Wongthep W. , Srituileong S. , Martwiset S. , Amnuaypanich S. 
Published: May 2012

AbstractPoly(vinyl alcohol) (PVA) was grafted on natural rubber (NR) latex particles (NR‐g‐PVA) using potassium persulfate to generate active radicals on both NR particle surface as well as PVA molecules. 1H‐ and 13C‐nuclear magnetic resonance spectroscopy suggested a possibly chemical attachment of PVA on the NR. The amount of graft‐PVA expressed in term of grafting percentage (%G) increased almost linearly with the amount of PVA adding to the NR latex. Measuring by dynamic light scattering, the particle size of NR‐g‐PVA particles was larger than the size of unmodified NR, also it increased with the molecular weight and %G of PVA. Transmission electron microscopy images of the NR‐g‐PVA latex particles revealed that the size of PVA‐grafted NR particle was enlarged by a layer of graft‐PVA surrounding the NR particle. Given by the graft‐PVA layer surrounding NR particles, the NR‐g‐PVA latex particles possessed better colloidal stability as lowering pH compared with the unmodified NR latex. Comparing with unmodified NR particles, the electrophoretic mobility of NR‐g‐PVA particles was lower due to the presence of graft‐PVA that shifted the shear plane further away from the surface of the particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Analysis of Dental Root Apical Morphology: A New Method for Dietary Reconstructions in Primates
Authors: Hamon NoÉmie , Emonet Edouard‐Georges , Chaimanee Yaowalak , Guy Franck , Tafforeau Paul , Jaeger Jean‐Jacques 
Published: May 2012

AbstractThe reconstruction of paleo‐diets is an important task in the study of fossil primates. Previously, paleo‐diet reconstructions were performed using different methods based on extant primate models. In particular, dental microwear or isotopic analyses provided accurate reconstructions for some fossil primates. However, there is sometimes difficult or impossible to apply these methods to fossil material. Therefore, the development of new, independent methods of diet reconstructions is crucial to improve our knowledge of primates paleobiology and paleoecology. This study aims to investigate the correlation between tooth root apical morphology and diet in primates, and its potential for paleo‐diet reconstructions. Dental roots are composed of two portions: the eruptive portion with a smooth and regular surface, and the apical penetrative portion which displays an irregular and corrugated surface. Here, the angle formed by these two portions (aPE), and the ratio of penetrative portion over total root length (PPI), are calculated for each mandibular tooth root. A strong correlation between these two variables and the proportion of some food types (fruits, leaves, seeds, animal matter, and vertebrates) in diet is found, allowing the use of tooth root apical morphology as a tool for dietary reconstructions in primates. The method was then applied to the fossil hominoid Khoratpithecus piriyai, from the Late Miocene of Thailand. The paleo‐diet deduced from aPE and PPI is dominated by fruits (>50%), associated with animal matter (1–25%). Leaves, vertebrates and most probably seeds were excluded from the diet of Khoratpithecus, which is consistent with previous studies. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.
Dual‐Acting Diether Derivatives of Piperidine and Homopiperidine with Histamine H3 Receptor Antagonistic and Anticholinesterase Activity
Authors: Bajda Marek , Kuder Kamil J. , Łażewska Dorota , Kieć‐Kononowicz Katarzyna , Więckowska Anna , Ignasik Michalina , Guzior Natalia , Jończyk Jakub , Malawska Barbara 
Published: May 2012

AbstractThe study presents novel biological properties of diether derivatives of homo‐ or substituted piperidine ligands of the histamine H3 receptor. The compounds were evaluated for their inhibitory potency against acetylcholinesterase (AChE) from the electric eel and butyrylcholinesterase (BuChE) from horse serum. The most interesting multifunctional compound 13 displayed high affinity for the cloned hH3R (Ki = 3.48 nM) and moderate inhibitory potency against both enzymes (IC50 AChE = 7.91 µM and BuChE = 4.97 µM). Molecular modeling studies revealed interactions with key amino acid residues in the homology model of histamine H3 receptor ligands, as well as the binding model for AChE and BuChE in the catalytic and peripheral active sites.
Proteolytic inactivation of α1‐antitrypsin and α1‐antichymotrypsin by neutrophils in arthritic joints
Authors: Abbink Jannie J. , Kamp Angela M. , Nuijens Jan H. , Swaak Tom J. G. , Hack C. Erik 
Published: May 2012

AbstractObjective. In vitro, activated neutrophils create a microenvironment in which proteinase inhibitors are inactivated through the coordinate action of reactive oxygen species and released elastase. We investigated whether such a mechanism may contribute to the destruction of the joint tissues in arthritis.Methods. We analyzed the state of α1‐antitrypsin (α1AT) and α1‐antichymotrypsin (α1ACT), the two major inhibitors of the neutrophilic serine proteinases, in synovial fluid (SF) from patients with inflammatory arthropathies (n = 71) and osteoarthritis (OA) (n = 11), and related the results to neutrophil activation in SF.Results. The ratio of functional to antigenic levels of α1AT in SF of patients with inflammatory joint diseases was similar to that of α1AT in normal plasma, whereas that of α1ACT was significantly decreased. Patients with inflammatory arthropathies had significantly higher levels of inactivated α1AT (iα1AT) and inactivated α1ACT (iα1ACT) in SF (as determined with monoclonal antibodies specific for the inactivated [i.e., proteolytically inactivated and/or complexed] forms of these inhibitors) than patients with OA (P < 0.005). Inactivated α1AT and iα1ACT levels corresponded to 0.3–11% and 3–99%, respectively, of the total amount of these inhibitors in SF. Most of the iα1AT in SF had a lower Mr than that of native α1AT. Inactivated α1ACT in SF had an Mr identical to that of nonfunctional α1ACT in plasma treated with chymotrypsin. Levels of both iα1AT and iα1ACT correlated significantly with lactoferrin and elastase levels.Conclusion. These results suggest that α1AT and α1ACT in arthritic joints are inactivated in part by activated neutrophils, suggesting a role for these cells in impairment of the local balance between proteinases and their inhibitors in arthritis.
Metalloproteinases, tissue inhibitor, and proteoglycan fragments in knee synovial fluid in human osteoarthritis
Authors: Lohmander L. Stefan , Hoerrner Lori A. , Lark Michael W. 
Published: May 2012

AbstractObjective. To determine the concentrations of human stromelysin‐1, collagenase, tissue inhibitor of metalloproteinases (TIMP), and proteoglycan fragments in knee synovial fluid in patients with injury to the meniscus or anterior cruciate ligament, posttraumatic osteoarthritis, primary osteoarthritis, or pyrophosphate arthritis.Methods. Synovial fluid samples were collected from patients with knee disease diagnosed arthroscopically and radiologically. Concentrations of stromelysin‐1, collagenase, and TIMP‐1 were determined by sandwich immunoassay, using monoclonal and polyclonal antibodies. Fragments of cartilage proteoglycan containing the chondroitin sulfate‐binding region were determined by immunoassay with a polyclonal antibody.Results. Average concentrations of metalloproteinases, TIMP, and proteoglycan fragments in joint fluid were significantly elevated in patients from all disease groups as compared with volunteers with healthy knees (reference group). Stromelysin concentrations in disease groups averaged 15–45 times that of the reference group. The molar ratios between stromelysin and collagenase varied between 10 and 150. The molar ratio between total stromelysin and free TIMP was 0.5 in the reference group and between 1.6 and 5.3 in the disease groups.Conclusion. Stromelysin concentration in joint fluid is a parameter that distinguishes diseased joints from healthy joints, with a sensitivity of 84% and a specificity of 90%. The high concentrations of metalloproteinase relative to TIMP in joint fluid from patients with the conditions studied may be associated with cartilage matrix degradation in these arthritides.
Increased levels of IgA antibodies to cytokeratin‐18 and epidermal keratin in rheumatoid arthritis
Authors: Borg A. A. , Dawes P. T. , Mattey D. L. 
Published: May 2012

AbstractObjective. To investigate whether levels of antibodies to cytokeratin‐18 (CK‐18) and epidermal keratin (EPK) were raised in patients with rheumatoid arthritis (RA).Methods. We measured antibodies to CK‐18 and EPK in patients with RA and in patients with osteoarthritis (OA), as well as in normal control subjects by means of an enzyme‐linked immunosorbent assay.Results. IgA antibodies to both CK‐18 and EPK were significantly increased in patients with RA compared with the controls and with patients with OA (P < 0.0001). No difference was noted in the levels of IgG or IgM antibodies to CK‐18 or EPK between controls and patients with OA or RA.Conclusion. Raised levels of IgA autoantibody to CK‐18 and EPK may reflect damage to cytokeratin‐containing cells (e.g., in synovial endothelium) and could be a useful disease marker in RA.
Increased production of soluble CD23 in rheumatoid arthritis, and its regulation by interleukin‐4
Authors: Chomarat Pascale , Briolay Jérôme , Banchereau Jacques , Miossec Pierre 
Published: May 2012

AbstractObjective. To assess CD23 status in rheumatoid arthritis (RA) patients, as defined by the levels of CD23 expression on peripheral blood mononuclear cells (PBMC), the levels of soluble CD23 (sCD23) in sera, and the production of sCD23 by PBMC cultures and its regulation by interleukin‐4 (IL‐4).Methods. CD23 expression as determined by double fluorescence‐activated cell sorter analysis and sCD23 production as determined by immunoradiometric assay were investigated in 24 RA patients and 21 controls. Soluble CD23 was measured in sera and supernatants of PBMC, activated with polyclonal activators (pokeweed mitogen [PWM] or Staphylococcus aureus Cowan strain 1, [SAC]) used either alone or in combination with IL‐2 or IL‐4.Results. The percentage of B cells expressing CD23 and serum levels of sCD23 were increased in patients with RA. IL‐4 was a potent inducer of sCD23 production in supernatants, whereas IL‐2 was inactive. Costimulation with SAC or PWM did not increase the effect obtained with IL‐4 alone. When sCD23 levels in RA and control supernatants were compared, spontaneous production was found to be increased in RA PBMC. This difference from control values was even more pronounced when sCD23 levels in PBMC and purified B cells in response to IL‐4, either alone or in combination with SAC or PWM, were tested. In the same supernatants, the increased secretion of sCD23 induced by IL‐4 was associated with an inhibitory effect of IL‐4 on Ig production, a phenomenon that was more pronounced in RA PBMC than in controls.Conclusion. CD23 status in RA is characterized by increased expression of CD23 on B cells, increased production of sCD23 in sera and supernatants, and increased sensitivity of RA PBMC and B cells to IL‐4.