bluuebunny/crossref_metadata_2025 huggingface dataset:
Pten Loss in CD4 T Cells Enhances Their Helper Function but Does Not Lead to Autoimmunity or Lymphoma
Authors: Soond Dalya R. , Garçon Fabien , Patton Daniel T. , Rolf Julia , Turner Martin , Scudamore Cheryl , Garden Oliver A. , Okkenhaug Klaus
Published: May 2012

PTEN, one of the most commonly mutated or lost tumor suppressors in human cancers, antagonizes signaling by the PI3K pathway. Mice with thymocyte-specific deletion of Pten rapidly develop peripheral lymphomas and autoimmunity, which may be caused by failed negative selection of thymocytes or from dysregulation of postthymic T cells. We induced conditional deletion of Pten from CD4 Th cells using a Cre knocked into the Tnfrsf4 (OX40) locus to generate OX40CrePtenf mice. Pten-deficient Th cells proliferated more and produced greater concentrations of cytokines. The OX40CrePtenf mice had a general increase in the number of lymphocytes in the lymph nodes, but not in the spleen. When transferred into wild-type (WT) mice, Pten-deficient Th cells enhanced anti-Listeria responses and the clearance of tumors under conditions in which WT T cells had no effect. Moreover, inflammatory responses were exaggerated and resolved later in OX40CrePtenf mice than in WT mice. However, in contrast with models of thymocyte-specific Pten deletion, lymphomas and autoimmunity were not observed, even in older OX40CrePtenf mice. Hence loss of Pten enhances Th cell function without obvious deleterious effects.
A p53 Axis Regulates B Cell Receptor-Triggered, Innate Immune System-Driven B Cell Clonal Expansion
Authors: Lee Hyunjoo , Haque Shabirul , Nieto Jennifer , Trott Joshua , Inman John K. , McCormick Steven , Chiorazzi Nicholas , Mongini Patricia K. A.
Published: May 2012

Resting mature human B cells undergo a dynamic process of clonal expansion, followed by clonal contraction, during an in vitro response to surrogate C3d-coated Ag and innate immune system cytokines, IL-4 and BAFF. In this study, we explore the mechanism for clonal contraction through following the time- and division-influenced expression of several pro- and anti-apoptotic proteins within CFSE-labeled cultures. Several findings, involving both human and mouse B cells, show that a mitochondria-dependent apoptotic pathway involving p53 contributes to the high activation-induced cell death (AICD) susceptibility of replicating blasts. Activated B cell clones exhibit elevated p53 protein and elevated mRNA/protein of proapoptotic molecules known to be under direct p53 transcriptional control, Bax, Bad, Puma, Bid, and procaspase 6, accompanied by reduced anti-apoptotic Bcl-2. Under these conditions, Bim levels were not increased. The finding that full-length Bid protein significantly declines in AICD-susceptible replicating blasts, whereas Bid mRNA does not, suggests that Bid is actively cleaved to short-lived, proapoptotic truncated Bid. AICD was diminished, albeit not eliminated, by p53 small interfering RNA transfection, genetic deletion of p53, or Bcl-2 overexpression. DNA damage is a likely trigger for p53-dependent AICD because susceptible lymphoblasts expressed significantly elevated levels of both phosphorylated ataxia telangiectasia mutated-Ser1980 and phospho-H2AX-Ser139. Deficiency in activation-induced cytosine deaminase diminishes but does not ablate murine B cell AICD, indicating that activation-induced cytosine deaminase-induced DNA damage is only in part responsible. Evidence for p53-influenced AICD during this route of T cell-independent clonal expansion raises the possibility that progeny bearing p53 mutations might undergo positive selection in peripherally inflamed tissues with elevated levels of IL-4 and BAFF.
Signal-Transducing Adaptor Protein-2 Modulates Fas-Mediated T Cell Apoptosis by Interacting with Caspase-8
Authors: Sekine Yuichi , Yamamoto Chikako , Kakisaka Michinori , Muromoto Ryuta , Kon Shigeyuki , Ashitomi Dai , Fujita Natsuko , Yoshimura Akihiko , Oritani Kenji , Matsuda Tadashi
Published: May 2012

We found that an adaptor protein, signal-transducing adaptor protein (STAP)-2, is a new member of the Fas–death-inducing signaling complex and participates in activation-induced cell death in T cells. STAP-2 enhanced Fas-mediated apoptosis and caspase-8 aggregation and activation in Jurkat T cells. Importantly, STAP-2 directly interacted with caspase-8 and Fas, resulting in enhanced interactions between caspase-8 and FADD in the Fas–death-inducing signaling complex. Moreover, STAP-2 protein has a consensus caspase-8 cleavage sequence, VEAD, in its C-terminal domain, and processing of STAP-2 by caspase-8 was crucial for Fas-induced apoptosis. Physiologic roles of STAP-2 were confirmed by observations that STAP-2–deficient mice displayed impaired activation-induced cell death and superantigen-induced T cell depletion. Therefore, STAP-2 is a novel participant in the regulation of T cell apoptosis after stimulation.
Clinical Leptospirosis in Three Cats (2001–2009)
Authors: Arbour Josianne , Blais Marie-Claude , Carioto Lisa , Sylvestre Doris
Published: May 2012

Based on previous research, cats were thought to have been resistant to the development of clinical signs following infection with Leptospira spp. This case report presents three confirmed, naturally infected clinical cases of feline leptospirosis. The cases presented were all indoor/outdoor cats that were known to hunt. They were also all presented at different stages of renal insufficiency; however, they did not show any liver involvement. The authors suggest that there may be a longer incubation period in cats than dogs and recommend further research in the form of a large, clinical study.
Bilateral Ventriculocordectomy via Ventral Laryngotomy for Idiopathic Laryngeal Paralysis in 88 Dogs
Authors: Zikes Cynthia , McCarthy Timothy
Published: May 2012

Bilateral ventriculocordectomy through a ventral median laryngotomy was performed for the treatment of idiopathic laryngeal paralysis in 88 dogs. The purpose of this retrospective analysis was to provide long-term follow-up for a large number of dogs surgically managed with this technique. A combination of medical record and completed client questionnaire information provided short-term (14 days) follow-up for 88 dogs and long-term (>6 mo) follow-up for 42 dogs. Major short-term postoperative complications were identified in 3 of 88 (3.4%) patients. Major long-term complications were identified in 3 of 42 (7.1%) patients. The results of surgery were considered to be very satisfactory in 93% and unsatisfactory in 7%. Three dogs in this series developed aspiration pneumonia. Bilateral ventriculocordectomy through a ventral median laryngotomy is associated with a low incidence of both short- and long-term complications. Due to the ease of this procedure, the minimal surgical trauma to the patient, and the satisfactory results, this surgery should be considered an option for the treatment of idiopathic laryngeal paralysis in the dog.
Novel Cutaneous Use of Implantable Loop Recorders in Two Dogs with Unexplained Episodes of Collapse
Authors: Sanders Robert , Olivier N. Bari
Published: May 2012

Determining the cause of episodes of collapse can be difficult. Even in patients with frequent collapsing episodes due to cardiac causes, diagnostic surface electrocardiogram and 24 hr ambulatory electrocardiographic (Holter) monitoring are sometimes inconclusive. Event monitors with multiple leads can be challenging to use in veterinary medicine over long periods of time due to lead dislodgment. Implantable leadless loop recorders (ILRs) are useful, but owners are sometimes unwilling to have an ILR implanted due to the associated risks and/or costs. In this case report, the authors describe the use of cutaneously placed ILRs in two dogs with unexplained episodes of collapse/exercise intolerance. Data recorded provided clinically useful information. Cutaneously placed ILRs can be used effectively in veterinary medicine to evaluate patients with unexplained episodes of collapse.
Goiter with Vascular Anomalies in a Litter of Polish Lowland Sheepdogs
Authors: Kuczynski Leslie Anne , Schwartz Paul , Peddle Gordon , Huang Steven , Mai Wilfried , Giger Urs
Published: May 2012

At approximately 4–5 mo of age, three Polish Lowland sheepdog puppies from a single litter of eight puppies presented to their respective primary veterinarians with bilateral subcutaneous masses in their ventral cervical regions. Evaluation, including thyroid function testing, surgical exploration with resection, computed tomography, and angiography, identified the masses as enlarged thyroid glands with severely dilated and abnormal vasculature in the regions of the glands. The dogs were also found to have serum concentrations of thyroid hormones that were below the reference ranges. None of the three dogs showed clinical signs of hypothyroidism, except for the presence of goiter. One dog also had a patent ductus arteriosus that was surgically repaired. All dogs were clinically normal at 2 yr of age. This is the first report of major vascular anomalies associated with goiter in any species. The mechanism is unknown.
Routine Use of Color Doppler in Fetal Heart Scanning in a Low-Risk Population
Authors: Eggebø Torbjørn Moe , Heien Claudia , Berget Magne , Ellingsen Christian Lycke
Published: May 2012

Objectives. To investigate the detection rate of major fetal heart defects in a low-risk population implementing routine use of color Doppler. Material and Methods. In a prospective observational study, all women undergoing fetal heart scanning (including 6781 routine examinations in the second trimester) during a three-year period were included. First a gray-scale scanning was performed including assessment of the four-chamber view and the great vessels. Thereafter three cross-sectional planes through the fetal thorax were assessed with color Doppler. Results. Thirty-nine fetuses had major heart defects, and 26 (67%) were prenatally detected. In (35%) of cases the main ultrasound finding was related to the use of color Doppler. The survival rate of live born children was 91%. Conclusions. Routine use of color Doppler in fetal heart scanning in a low-risk population may be helpful in the detection of major heart defects; however, still severe malformations were missed prenatally.
Mass Spectrometry for Diabetic Nephropathy Monitoring: New Effective Tools for Physicians
Authors: Lapolla Annunziata , Porcu Simona , Traldi Pietro
Published: May 2012

The main aim of diabetic nephropathy monitoring is to identify molecular markers, that is, to find changes occurring at metabolome and proteome levels indicative of the disease’s development. The mass spectrometry methods available today have been successfully applied to this field. This paper provides a short description of the basic aspects of the mass spectrometric methods used for diabetic nephropathy monitoring, reporting and discussing the results obtained using different approaches.
Radiolysis of Commercial Dyes in Aqueous Solutions to Produce Dosimeters for Gamma Dosimetry
Authors: Taqmeem Hussain  , Muhammad Yousuf Hussain  , Muhammad Shahbaz  , Inam-ul-Haq  , Hashim Farooq  , Shaukat Ali
Published: May 2012

The usability of aqueous solutions of SR C4BLN and SGY CRL dyes; as secondary dosimeter was confirmed. All samples were irradiated by Co60 γ-source in the range 0-105Gy. Absorbance of solutions was noted at λmax for pre and post irradiation stages. The λmax of Red and Yellow dyes were 545nm and 448nm respectively. The absorbance% and the %discoloration of each dye were determined. Sample solutions showed a gradual decrease in Absorbance% and increase in %age discoloration versus absorbed doses.
Scanning Electrochemical Microscopy
Authors: Amemiya Shigeru
Published: May 2012

In this article, we introduce the principle of scanning electrochemical microscopy (SECM) and its applications as a powerful electrochemical method for material characterization. The principle of SECM is based on the use of a micrometer‐ or nanometer‐sized ultramicroelectrode as the scanning chemical probe of electrons, ions, and molecules that are transferred across the interface between a target solid material and an electrolyte solution as well as air/liquid and liquid/liquid interfaces and membranes. In comparison to traditional electrochemical methods, SECM is much higher in spatial resolution and mass transport to find its advantages in the chemical imaging of a heterogeneously reactive material surface and the quantitative study of interfacial reaction dynamics. The unique capability of imaging an interfacial reactivity renders SECM complementary to other scanning probe microscopy techniques and also combinable with them to yield multidimensional images of the material surface. In this article, various operation modes of SECM are introduced and followed by examples of practical measurements based on imaging, approach curve, voltammetry, and amperometry. Present limits of the technique in both theory and experiment are briefly discussed. In addition, numerical and analytical approaches to data analysis as well as experimental protocols for tip fabrication and characterization are described.
Low‐Field Magnetoresistance in La0.67Sr0.33MnO3:ZnO Composite Film
Authors: Staruch Margo , Gao Haiyong , Gao Pu‐Xian , Jain Menka
Published: May 2012

A nanocomposite film of La0.67Sr0.33MnO3 (LSMO):ZnO is synthesized by depositing LSMO solution on a vertical array of ZnO nanorods grown on (0001) Al2O3 substrate. The magnetic behavior of the composite film differs from that of a pure LSMO film, possibly due to smaller grain size in the composite, small amount of Zn doping, or the presence of nonmagnetic ZnO phase near the LSMO grain boundaries. Magnetotransport measurements show that the low‐field magnetoresistance (LFMR) of the nanocomposite film is significantly enhanced as compared to that observed for pure LSMO film. The highest value of the LFMR of the nanocomposite film at 10 K is –23.9% with a magnetic field of 0.5 T applied parallel to the current.
Three Dimensional PtRh Alloy Porous Nanostructures: Tuning the Atomic Composition and Controlling the Morphology for the Application of Direct Methanol Fuel Cells
Authors: Zhang Yuan , Janyasupab Metini , Liu Chen‐Wei , Li Xinxin , Xu Jiaqiang , Liu Chung‐Chiun
Published: May 2012

A strategy for the synthesis of PtRh alloy 3D porous nanostructures by controlled aggregation of nanoparticles in oleylamine is presented. The atomic ratio between the two components (Pt and Rh) is tuned by varying the concentration of precursor salts accommodating the oxidation of methanol. The morphology of PtRh alloy nanostructure is controlled by elevating the temperature of the reaction system to 240 °C. The prepared 3D porous nanostructures provide a high degree of electrochemical activity and good durability toward the methanol oxidation reaction compared to those of the commercial Pt/C (E‐TEK) and PtRh nanoparticles. Therefore, the 3D alloy porous nanostructures provide a good opportunity to explore their catalytic properties for methanol oxidation.
The brain‐derived neurotrophic‐factor (BDNF) val66met polymorphism is associated with geriatric depression: A meta‐analysis
Authors: Pei Yu , Smith Alicia K. , Wang Yongjun , Pan Yanli , Yang Jian , Chen Qi , Pan Weigang , Bao Feng , Zhao Lisha , Tie Changle , Wang Yizheng , Wang Jian , Zhen Wenfeng , Zhou Jinxia , Ma Xin
Published: May 2012

Depression has been associated with reduced expression of brain‐derived neurotrophic factor (BDNF) in the hippocampus. Genetic association studies of theBDNFVal66Met polymorphism (rs6265) in geriatric depression have produced inconsistent results. A meta‐analysis of studies was conducted to compare the frequency of theBDNFVal66Met variant between cases with geriatric depression and age‐matched controls. A total of five studies involving 523 cases with geriatric depression and 1,220 psychiatrically healthy controls was included. Met allele carriers had an increased risk for geriatric depression when compared to Val/Val homozygotes (P = 0.004, OR = 1.48, 95% CI = 1.13–1.93). Our findings suggest theBDNFMet allele may confer increased risk for depression as individual age. © 2012 Wiley Periodicals, Inc.
Modification of polypropylene via the free‐radical grafting ternary monomer in water suspension systems
Authors: Zhu Baodong , Dong Weichao , Wang Jian , Song Jun , Dong Qun
Published: May 2012

Maleic anhydride, styrene, and butyl acrylate were grafted onto polypropylene (PP) via free‐radical polymerization. The grafted product, polypropylene‐g‐(maleic anhydride–styrene–butyl acrylate) (PP‐g‐PMSB), was prepared in a water suspension system, and a nongrafted polymer, poly(maleic anhydride–styrene–butyl acrylate) (PMSB′), was produced at the same time. The optimal synthesis conditions were determined by orthogonal experiments. The crystallinity, thermal stability, melt flow rate, and hydrophilicity of the grafting samples were investigated in the presence or absence of PMSB′. The results indicate that the grafting percentage (Gp) of PP‐g‐PMSB and the content of PMSB′ (Cm) increased as the monomer content increased under the optimum reaction conditions. All of these ternary monomers were grafted onto the PP backbone as long‐chain branches. With increasing Gp, PP‐g‐PMSB's polarity and thermal stability increased, the crystallinity decreased, and the molecular distribution became narrower. The contact angle decreased to 72.12° when Gp was 6.87%. With increasing Cm, the crystallinity and thermal stability of the grafting products decreased compared to PP‐g‐PMSB and the molecular distribution grew wider. The contact angle decreased to 63.51° when Cm was 3.64%; this indicated that the presence of PMSB′ further improved the hydrophilicity of the grafted products. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of binary combined systems of antioxidants on the stabilization of peroxide‐cured low‐density polyethylene
Authors: Zhang Xiaohu , Yang Hongmei , Song Yihu , Zheng Qiang
Published: May 2012

The secondary antioxidants Irganox 168 and 242 and dilaurylthiodipropionate (didodecyl‐3,3′‐thiodipropionate) (DLTP) were chosen to be combined with the primary phenol antioxidants Irganox 300, 1010, 1035, and 1076, and the effects of the binary combined systems of antioxidants on the peroxide curing reaction and the long‐term stability of crosslinked low‐density polyethylene (XLPE) were studied through isothermal dynamic rheological and mechanical testing. The results show that the primary phenol antioxidants with lower melting points had better resistance to scorching and exhibited good synergistic effects with the secondary antioxidants. Irganox 168 had little resistance to scorching, whereas Irganox DLTP had moderate resistance, and Irganox 242 had the greatest resistance. Irganox 168 and DLTP guaranteed the mechanical properties well, whereas Irganox 242 reduced the tensile strength obviously. Irganox 300 and 1035 combined with secondary antioxidants performed poorly in long‐term thermal aging test, whereas Irganox 1076 in combination with secondary antioxidants displayed a moderate effect of aging resistance, and Irganox 1010 showed the best effect. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012
Preparation and characterization of grafting polyacrylamide from PET films by SI‐ATRP via water‐borne system
Authors: Zhang Hongwen , Du Zhenyu , Jiang Yan , Yu Qiang
Published: May 2012

The grafted homopolymer and comb‐shaped copolymer of polyacrylamide were prepared by combining the self‐assembly of initiator and water‐borne surface‐initiated atom transfer radical polymerization (SI‐ATRP). The structures, composition, properties, and surface morphology of the modified PET films were characterized by FTIR/ATR, X‐ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by equable grafting polymer layer after grafted polyacrylamide (PAM). The amount of grafting polymer increased linearly with the polymerization time added. The GPC date show that the polymerization in the water‐borne medium at lower temperature (50°C) shows better “living” and control. After modified by comb‐shaped copolymer brushes, the modified PET film was completely covered with the second polymer layer (PAM) and water contact angle decreased to 13.6°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Bis(N‐benzyl piperazino) thiuram disulfide and dibenzothiazyl disulfide as synergistic safe accelerators in the vulcanization of natural rubber
Authors: Alam Md. Najib , Mandal Swapan Kumar , Debnath Subhas Chandra
Published: May 2012

Some investigation regarding the effect of binary system of accelerators comprising one safe thiuram disulfide, namely bis(N‐benzyl piperazino) thiuram disulfide (BPTD) and dibenzothiazyl disulfide (MBTS), on the vulcanization of NR is carried out. The results are compared with those obtained with conventional tetra methyl thiuram disulfide (TMTD) presently considered as unsafe. The vulcanizates obtained from safe synergistic pair of accelerators (BPTD‐MBTS) possess comparable mechanical properties [modulus, tensile strength, and elongation at break (%)] and exhibits some improvement in heat resistant behavior when compared with those obtained with TMTD‐MBTS system. In the light of mechanical properties, safe BPTD‐MBTS system introduces the safe noncarcinogenic rubber accelerator in the vulcanization of rubber. Same type of synergistic activity may be due to comparable activation energy for both the TDs with the combination of MBTS. Although rate constant values are low for BPTD‐MBTS (6 : 3) compared to TMTD‐MBTS (6 : 3) in the high temperature vulcanization, the crosslinking efficiency of former is very large compared to later. This may be responsible for improvement in heat resistance behavior of the novel accelerator in the combination with MBTS. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Grafting polymer brushes on graphene oxide for controlling surface charge states and templated synthesis of metal nanoparticles
Authors: Gao Tingting , Ye Qian , Pei Xiaowei , Xia Yanqiu , Zhou Feng
Published: May 2012

In this article, poly[(dimethylamino)ethyl methacrylate] (PDMAEMA) brushes were grafted onto graphene oxide (GO) sheet via noncovalent modification of pyrene terminated initiator and subsequent in situ surface‐initiated atom transfer radical polymerization (SI‐ATRP). The results of zeta‐potentials, dispersivity measurement as well as the permeability of cationic and anionic redox‐active probe molecules reveal that the as‐prepared GO/PDMAEMA composite exhibits zwitterionicity because of the presence of phenol hydroxyl, carboxyl, and amine groups and the charging state can be manipulated by controlling pH values. Furthermore, by ion exchange and in situ reduction, palladium and gold nanoparticles were successfully uploaded and the catalytic property of the uniformly distributed Pd‐Au nanoparticles on GO sheet was investigated. These results reported in this work may open primarily toward constructing a bridge among GO, charged polymer and metal nanoparticles and secondarily to represent a new strategy for uniformly depositing inorganic nanoparticles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Fatigue and hysteresis behavior of halloysite nanotubes‐filled natural rubber (SMR L and ENR 50) nanocomposites
Authors: Ismail H. , Salleh S. Z. , Ahmad Z.
Published: May 2012

The effect of various halloysite nanotubes (HNTs) loading on fatigue life, stress–strain behavior, and hysteresis of HNTs/Standard Malaysian Rubber (SMR) L and HNTs/epoxidized natural rubber (ENR) 50 nanocomposites were studied. The addition of HNTs caused decrement in fatigue life for both nanocomposites at any extension ratio. Generally, HNTs/SMR L nanocomposites showed higher fatigue life than ENR 50 nanocomposites. Addition of more HNTs caused decrement of stress for HNTs/SMR L nanocomposites, whereas HNTs/ENR 50 nanocomposites showed vice versa at any strain. This result was supported by the graph of accumulated strain energy against extension ratio. Hysteresis values increased with addition of HNTs in both nanocomposites where of HNTs/ENR 50 nanocomposites exhibited higher hysteresis than HNTs/SMR L nanocomposites at any HNTs loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Ultra‐violet curable resin based on palm oil: Determination of reaction condition and characterization of the resin
Authors: Rozman H. D. , Tai N. L. , Tay G. S.
Published: May 2012

In this study, a UV curable resin based on palm oil was prepared by modifying palm oil with glycerol and glycidyl methacrylate (GMA). First, monoglyceride (MG) was prepared from a mixture of palm oil and glycerol at a ratio of 1 : 2 based on equivalent basis. The MG was treated with GMA to introduce unsaturated groups to MG chain via etherification between epoxy group (from GMA) and hydroxyl group (from MG). The amount of catalyst needed, reaction temperature, and time for this chemical modification were determined. The completion of reaction between GMA and monoglyceride was measured using Fourier transform infrared (FTIR) spectroscopy by monitoring the disappearance of the epoxy group in FTIR spectrum. An increment at peak 1630 cm−1 in FTIR spectrum was observed when more GMA was used in the chemical modification. Viscosity test and gel permeation chromatography analysis were carried out to characterize the resin produced. The resin was then cured using UV radiation and the properties of the cured resin were measured. From the results, the gel content of the cured resin was more than 97%. The hardness of the MG‐GMA film was influenced by the amount of GMA used. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and characterization of graphene oxide/poly(vinyl alcohol) composite nanofibers via electrospinning
Authors: Wang Chen , Li Yadong , Ding Guqiao , Xie Xiaoming , Jiang Mianheng
Published: May 2012

Graphene oxide (GO) was well dispersed in poly(vinyl alcohol) (PVA) diluted aqueous solution, and then the mixture was electrospun into GO/PVA composite nanofibers. Electron microscopy and Raman spectroscopy on the as‐prepared and calcined samples confirm the uniform distribution of GO sheets in the nanofibers. The thermal and mechanical properties of the nanofibers vary considerably with different GO filler contents. The decomposition temperatures of the GO/PVA composite nanofiber dropped by 38–50°C compared with pure PVA. A very small loading of 0.02 wt % GO increases the tensile strength of the nanofibers by 42 times. A porous 3D structure was realized by postcalcining nanofibers in H2. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Bond properties of structural polypropylene fiber in hybrid nonstructural polypropylene and structural polypropylene fiber‐reinforced latex‐modified cement‐based composites
Authors: Jung Ji‐Youn , Park Chan‐Gi , Park Jong‐Sik
Published: May 2012

This study investigated the effect of styrene–butadiene latex (latex) content on the pullout behavior of structural polypropylene fibers (SPF) in hybrid fiber‐reinforced latex‐modified cement‐based composite made with a blend of SPF and nonstructural polypropylene fiber. Bond tests were performed in accordance with JCI SF‐8. NSPF was incorporated at 9.10 kg/m3 and SPF at 0.45 kg/m3. Latex was added at 0–20% of the binder weight. The experimental results demonstrated that latex improved the pullout properties of the load–displacement curve in the debonded zone. Also, the bond strength and interface toughness increased with latex content up to 15% but decreased when the latex content reached 20%. Microstructure analysis showed increased scratching on the SPF surface. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis, characterization, and thermal properties of alkyl‐functional naphthoxazines
Authors: Uyar Tamer , Hacaloglu Jale , Ishida Hatsuo
Published: May 2012

A series of alkyl‐functional naphthoxazine resins having various alkyl chain lengths from C1 to C18 are synthesized with a high yield and high purity by the reactions of 1,5‐dihydroxynaphthalene, formaldehyde, and aliphatic amines. The proposed chemical structures of the naphthoxazines are confirmed by high‐resolution mass spectrometry, 1H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and pyrolysis mass spectrometry studies. The alkyl‐functional naphthoxazines have shown low polymerization temperature characteristics where polymerization of these monomers is achieved in the range of 150–170°C yielding cross‐linked polynaphthoxazines. The low‐temperature polymerization characteristics and the associated thermal degradation behaviors are studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Free‐radical grafting of trans‐ethylene‐1,2‐dicarboxylic acid onto molten ethylene‐vinyl acetate copolymer
Authors: Krivoguz Yuri M. , Guliyev Abasgulu M. , Pesetskii Stepan S.
Published: May 2012

Distinctive features of free‐radical grafting of trans‐ethylene‐1,2‐dicarboxylic acid (TEDA) onto macromolecules of molten ethylene‐vinyl acetate copolymer (EVA) in the course of reactive extrusion have been investigated along with structure, mechanical characteristics, and high‐elastic properties of molten functionalized products (EVA‐g‐TEDA). It is shown that EVA‐g‐TEDA yield depends on both the peroxide initiator concentration and content of vinyl acetate units in the copolymer molecular structure. At functionalization, acid grafting is accompanied by secondary reactions of macromolecular degradation and crosslinking. With a low‐peroxide initiator concentration (0.1 wt %), degradation prevails; with a higher (0.3 wt %) concentration, crosslinking of macromolecules prevails. It is reported that monomers being grafted attach mostly over secondary carbon atoms in the polymer chain. EVA‐g‐TEDA appears to have a less perfect crystal structure with a lower‐melting temperature and crystallinity as against the starting polymer. The functionalized products display enhanced rigidity and lower deformability in comparison with the initial copolymer. Variations in the swelling ratio and melt strength of EVA‐g‐TEDA depend on the course of competing secondary processes of macromolecular degradation and crosslinking. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Polyaniline–TiO2 hybrid‐coated cotton fabric for durable electrical conductivity
Authors: Savitha K. U. , Prabu H. Gurumallesh
Published: May 2012

A polyaniline–TiO2 hybrid was coated on cotton fabric to make it electrically conductive. A One‐pot method of synthesis with acetic acid medium was used, in which TiCl4 was used as precursor. The oxidative polymerization of aniline adsorbed on TiO2 (anatase form) was performed in the presence of cotton fabric. Fabric crystallinity was least affected by the coatings, as confirmed by XRD analysis. FTIR studies revealed interactions between fiber and hybrid. The morphological study through SEM showed the uniform coating of hybrid over the fibers of the cotton fabric and AFM analysis revealed the rod‐like structure of the hybrid. The strength of the coated fabrics was assessed using abrasion tests. The electrical conductivity was determined using electrochemical impedance spectroscopy (EIS).The conductivity value varied with respect toTiO2 content and ranged in the order 10−4 to 102S/cm. The effect of atmospheric aging was assessed. A more durable conductivity was observed in hybrid‐coated fabric than pristine polyaniline‐coated fabric. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Nonisothermal curing kinetics of a novel polymer containing phenylsilylene and propargyl–hexafluorobisphenol a units
Authors: Yang Guang , Yuan Zehong , Yang Zhiyong , Zhang Maning
Published: May 2012

A novel thermosetting polymer, poly[(phenylsilylene) propargyl–hexafluorobisphenol A] (PBAFS), with a new structure was synthesized. The structure of PBAFS and its cured resins were characterized by Fourier transform infrared spectra. During curing, a hydrosilylation reaction may occur between SiH and CC bonds and a Claisen rearrangement reaction of aryl propargyl ether led to formation of chromene, which immediately preceded polymerization on heating. The dynamic viscosity behavior was investigated by rheological experiment. Thermal stability of the cured PBAFS was also measured by Thermogravimetric analysis. The curing behavior of PBAFS was monitored by nonisothermal differential scanning calorimetry at different heating rates. The kinetic parameters and the kinetic model of the cure reaction were evaluated by Kissinger, Ozawa, and Friedman methods. The cure reaction of PBAFS was found nth‐order in nature and the prediction curves by Friedman method for nonisothermal curing reaction were in good agreement with the experimental curves. The isothermal curing time of PBAFS were predicted by Vyazovkin and model‐fitting methods from the nonisothermal kinetic parameters. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Chlorosulfonated polyethylene–polypropylene thermoplastic vulcanizate: Mechanical, morphological, thermal, and rheological properties
Authors: Mandal Asis K. , Siddhanta Samir K. , Chakraborty Debabrata
Published: May 2012

Different thermoplastic vulcanizate (TPV) blends were prepared from elastomeric chlorosulfonated polyethylene (CSM) and thermoplastic polypropylene (PP) by employing dynamic vulcanization technique. The mechanical properties of such blends were compared in respect of their stress at 25% modulus (25%M), ultimate tensile strength (UTS), percent elongation at break, and hardness to those of pure CSM. The mechanical analysis showed substantial improvement in stress at 25%M, UTS, and hardness values with the incorporation of 15–40 parts of thermoplastic contents (PP) (per hundred parts of blend). The two‐phase morphologies were clearly observed by scanning electron microscopy studies. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC studies showed a decreasing trend in glass transition temperature (Tg) and TGA studies indicated the increase in thermal stability of all TPV blends with respect to the elastomeric CSM. Rheological studies showed that there is an increasing trend in shear melt viscosity of TPV blends with the increase in PP amount as the higher content of isotactic PP used in the present case increases the melt viscosity. The TPVs obtained after the rheotron studies displayed identical shear stress/strain pattern when further subjected to the same study. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Biocidal nanofibers via electrospinning
Authors: Ren Xuehong , Kocer Hasan B. , Worley S. D. , Broughton R. M. , S. Huang T.
Published: May 2012

To achieve biocidal properties, a cyclic N‐halamine precursor, 7,7,9,9‐tetramethyl‐1,3,8‐triazaspiro[4.5]‐decane‐2,4‐dione (TTDD), was synthesized and introduced into nanosized polyacrylonitrile fibrous mat by an electrospinning technique. It was rendered antimicrobial by exposure to dilute hypochlorite solution. Synthesis routes and characterization data are presented. Scanning electron microscopy (SEM) demonstrated that the ultrafine fiber possessed average diameter 414 nm (from 240 to 650 nm). The chlorinated nanofibrous composites provided about 4.9 log reductions of both Gram‐positive bacteria Staphylococcus aureus (ATCC 6538) and Gram‐negative bacteria Escherichia coli O157:H7 (ATCC 43895) within 5 min of contact time. This is indicative of promising possible applications in the filtration of water and air. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Comparison of morphology and mechanical properties of peroxide‐cured acrylonitrile butadiene rubber/LDH composites prepared from different organically modified LDHs
Authors: Feng Jianxiang , Liao Zedong , Zhu Jin , Su Shengpei
Published: May 2012

Rubber compounds based on acrylonitrile butadiene rubber (NBR) containing organically modified layered double hydroxides (LDHs) were prepared using peroxide as a curing agent. The LDHs intercalated by organic compounds including sodium styrene sulfonate (SSS) and sodium dodecylbenzene sulfonate (SDBS) were investigated using thermogravimetric analysis (TGA) and X‐ray diffraction (XRD) while the unmodified LDHs were used as contrast. Experimental results from TGA and XRD showed that both SSS‐ and SDBS‐intercalated LDHs were successfully obtained. The morphology of the LDH composites was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and XRD. The chemical structure of NBR/LDHs compounds were measured by Fourier transform infrared spectrum. The thermal properties were measured by TGA and differential scanning calorimetry. Other properties such as mechanical and swelling properties were also investigated. The results showed that a chemical bonding between organically modified LDHs and rubber matrix through SSS was built during vulcanization, which leads to improved interfacial strength of the cured compound. A high‐performance acrylonitrile butadiene rubber/SSS‐modified LDH compound, which has two times higher tensile strength than cured pure rubber without significant loss of elongation, was obtained. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of nanoclay content and matrix composition on properties and stress–strain behavior of NR/EPDM nanocomposites
Authors: Alipour Abdolmajid , Naderi Ghasem , Ghoreishy Mir HamidReza
Published: May 2012

Nanocomposites based on NR/EPDM/Cloisite 15A have been prepared via a vulcanization process to investigate the effect of nanoclay content and rubber composition on the properties of samples. The prepared nanocomposite samples are characterized by several techniques. The experimental results of X‐ray diffraction and transmission electron microscopy showed the widening of distance between the silicate layers, penetration of polymer chains into silicate layers, and formation of an intercalated and partially exfoliated structure. Results indicated that addition of nanoclay could improve the mechanical strength of the rubber. Also increase of nanoclay and EPDM content were found to improve the thermal aging of the samples and also the performance of the rubbers under compression. Nanoclay also reduced the hysteresis and heat build up of the rubber compounds. Moreover, to investigate the stress–strain behavior of NR/EPDM nanocomposites using constitutive models, applicability and best fit of five different hyperelastic constitutive models including second order Polynominal, Yeoh, third order Ogden, Marlow, and Arruda‐Boyce against experimental data for NR/EPDM/nanoclay blends were studied. Due to the different amounts of nanoclay (1, 3, 5, and 7 wt %) and different NR/EPDM compositions (100/0), (75/25), (50/50), (25/75), and (0/100), different experimentally measured data of samples were compared with those predicted by the mathematical models previously mentioned. Results showed that third order Ogden and Marlow models can be used for different amounts of nanoclay and rubber compositions, whereas Arruda‐Boyce and Yeoh models show more deviation from experimental data with a reduction in nanoclay and increase in EPDM content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Fabrication and characterization of natural origin chitosan‐ gelatin‐alginate composite scaffold by foaming method without using surfactant
Authors: Sharma Chhavi , Dinda Amit Kumar , Mishra Narayan Chandra
Published: May 2012

A natural origin tripolymer scaffold from chitosan, gelatin, and alginate was fabricated by applying foaming method without adding any foam stabilizing surfactant. Previously, in foaming method of scaffold fabrication, toxic surfactants were used to stabilize the foam, but in this work, the use of surfactant has been avoided strictly, which can provide better environment for cellular response and viability. In foaming method, stable foam is produced simply by agitating the polymer (alginate‐gelatin) solution, and the foam is crosslinked with CaCl2, glutaraldehyde, and chitosan to produce tripolymer alginate‐gelatin‐chitosan composite scaffold. Microscopic images of the composite scaffold revealed the presence of interconnected pores, mostly spread over the entire surface of the scaffold. The scaffold has a porosity of 90% with a mean pore size of 57 μm. Swelling and degradation studies of the scaffold showed that the scaffold possesses excellent properties of hydrophilicity and biodegradability. In vitro cell culture studies by seeding L929 mouse fibroblast cells on scaffold revealed excellent cell viability, proliferation rate and adhesion as indicated by MTT assay, DNA quantification, and phase contrast microscopy of cell‐scaffold construct. The natural origin composite scaffold fabricated by the simplest method i.e., foaming method, but without adding any surfactant, is cheap, biocompatible, and it might find potential applications in the field of tissue engineering. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Fabrication of size‐controllable mPEG‐decorated microparticles conjugating optically active ketoprofen based on self‐assembly of amphiphilic random copolymers
Authors: Li Xia , Zhou Guo‐Jun , Chu Guo‐Hai , Lin Xian‐Fu , Wang Jun‐Liang , Shen Kai , Yin Jie
Published: May 2012

Novel size‐controllable mPEG‐decorated polymeric microparticles binding optically active ketoprofen were successfully fabricated based on chemoenzymatic synthesis and self‐assembly of amphiphilic random polymer–ketoprofen conjugates with mPEG and (S)‐ketoprofen as pendants. A series of mPEG350‐ or mPEG1000‐functionalized amphiphilic random polymer–ketoprofen conjugates with drug loading capacity from 16.5% to 73.2% were easily prepared by combining enzymatic resolution with radical polymerization and characterized by Fourier Transform Infrared spectroscopy, 1H‐NMR, and gel permeation chromatography. The formation of aggregates from the amphiphilic random polymer–ketoprofen conjugates was investigated by ultraviolet‐visible absorption spectra using pyrene as the guest molecule. Transmission electron microscopy measurement revealed that the self‐assemblies were well dispersed as spherical microparticles. The size of the self‐assemblies could be widely tuned by varying the length of mPEG chains and the content of ketoprofen in the synthetic polymer–ketoprofen conjugates, and a series of mPEG‐decorated (S)‐ketoprofen‐bound polymeric microparticles with average radius from 70 nm to 1.1 μm were obtained. The successful preparation of the microparticles containing (S)‐ketoprofen provided a new strategy for the design and fabrication of optically active drug delivery systems. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis, characterization, and corrosion inhibition study of polyaniline‐α‐Fe2O3 nanocomposite
Authors: Umare S. S. , Shambharkar B. H.
Published: May 2012

Polyaniline (PANI)‐α‐Fe2O3 nanocomposites (NCs) have been synthesized by chemical oxidative in situ polymerization of aniline in presence of α‐Fe2O3 nanoparticles at 5°C using (NH4)2S2O8 as an oxidant in an aqueous solution of sodium dodecylbenzene sulphonic acid (SDBS), as surfactant and dopant under N2 atmosphere. The room temperature conductivity of NCs decreases and coercive force (Hc) increases with an increase addition of α‐Fe2O3 in PANI matrix. The result of FTIR and TGA shows that the interaction between α‐Fe2O3 particles and PANI matrix could improve the thermal stability of NCs. NCs demonstrate the superparamagnetic behavior. The performance of PANI and PANI‐α‐Fe2O3 NCs as protective coating, against corrosion of 316LN stainless steel in 3.5% NaCl was assessed by potentiodynamic polarization technique. The study shows a good corrosion inhibition effect of both the coatings. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Electropolymerization and properties of 3,4‐ethylenedioxythiophene backbone polymer with tetrathiafulvalene as pendant
Authors: Zhang Lei , Li Meijiang , Wang Chengyun , Wang Yanhong , Shen Yongjia
Published: May 2012

Three 3,4‐ethylenedioxythiophene (EDOT) derivatives, including an EDOT‐tetrathiafulvalene (TTF) derivative, were synthesized by Steglich esterification of carboxylic acids with hydroxymethyl EDOT (3,4‐ethylenedioxythiophene methanol). The UV spectra showed that there was no distinctive intramolecular interaction for the EDOT–TTF monomer between the EDOT and the TTF moieties in the ground state; however, the cyclic voltammetry responses implied that such intramolecular interaction occurred. Electropolymerization in excessive potential could bring in strong overoxidation effects and degradation in the polymer film. The polymers were simulated using density functional theory with Gaussian03 package and the optimized HOMO and LUMO state were figured out. The conductivity of TTF‐polymer was 6 S·cm−1 obtained by galvano station and 4.8 × 10−3 S·cm−1 obtained by potentiostatic electropolymerization after doping with 7,7,8,8‐tetracyanoquinodimethane. The results indicated that this polymer was a reasonable candidate for conducting materials and it was meaningful to increase the conductive dimensions of TTF polymers by chemical doping. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Induction of extremely low protein expression level by fusion of C‐terminal region of Nef
Authors: Takamune Nobutoki , Irisaka Yukari , Yamamoto Minami , Harada Keisuke , Shoji Shozo , Misumi Shogo
Published: May 2012

Nef is one of the accessory proteins of human immunodeficiency viruses. Here, we noted that the relative expression level of NefNL4‐3 is much lower than that of NefJR‐CSF in HEK293 cells. By evaluating the expression level using a Nef mutant, it was indicated that amino acids 129‐206 of NefNL4‐3, that is, the C‐terminal region named NLAA129‐206, could contain the region responsible for the induction of the low protein expression level. In addition, the expression levels of the enhanced green fluorescent protein and Renilla luciferase became extremely low with the fusion of NLAA129‐206. Interestingly, the NLAA129‐206‐corresponding sequences of other Nef variants with relatively high expression levels also induced the extremely low protein expression level by fusion. These results suggest that the C‐terminal region of Nef can generally induce an extremely low protein expression level. Here, we propose that the C‐terminal region of Nef could become an excellent tool for the induction of an extremely low expression level of arbitrary proteins by attachment as fusion proteins.
Oxidative ring‐opening of 2‐methylcyclohexanone catalysed by supported heteropolyacid catalysts for cetane number enhancement
Authors: Ren Rui , Yang Hong , Zheng Ying , Ng Siauw , Zhao Jianshe
Published: May 2012

Incipient wetness impregnation method was used to incorporate heteropolyacid H6[PV3Mo9O40]nH2O (HPA) on SiO2 at various HPA loadings (10, 20, 30, 40 wt.% HPA) and calcined temperatures. Catalytic activity of these synthesised catalysts were evaluated through oxidation of 2‐methylcyclohexanone to methyl 6‐oxoheptanoate which was a desired product. In the oxidative conditions the conversion and selectivity of the desired product methyl 6‐oxoheptanoate can reach as high as 97 and 94 wt.%, respectively. The results also suggested that the catalyst with 20 wt.% loading of HPA to be the best one. The catalysts were characterised using a variety of techniques including XRD, BET, FT‐IR and TGA‐DTA. The results indicated that HPA was well dispersed on the SiO2 supporting material. An engine ignition test following ASTM D6890 standard indicated that the oxidative ring‐opening of cyclohydrocarbons can have a positive impact on the cetane numbers and ignition delay time of fuels. © 2012 Canadian Society for Chemical Engineering