bluuebunny/crossref_metadata_2025 huggingface dataset:
Leptin promotes the proliferative response and invasiveness in human endometrial cancer cells by activating multiple signal-transduction pathways
Authors: Sharma D , Saxena N K , Vertino P M , Anania F A
Published: May 2006

An increase in the risk of cancer is one of the consequences of obesity. The predominant cancers associated with obesity have a hormonal basis and include breast, prostate, endometrium, colon and gall-bladder cancers. Leptin, the key player in the regulation of energy balance and body weight control also acts as a growth factor on certain organs in both normal and disease states. Therefore, it is plausible that leptin acts to promote cancer growth by acting as a mitogenic agent. However, a direct role for leptin in endometrial cancer has not been demonstrated. In this study, we analyzed the proliferative role of leptin and the mechanism(s) underlying this action in endometrial cancers which express both short and long isoforms of leptin receptors. Treatment with leptin resulted in increased proliferation of ECC1 and Ishikawa cells. The promotion of endometrial cancer cell proliferation by leptin involves activation of STAT3 and ERK2 signaling pathways. Moreover, leptin-induced phosphorylation of ERK2 and AKT was dependent on JAK/STAT activation. Therefore blocking its action at the JAK/STAT level could be a rational therapeutic strategy for endometrial carcinoma in obese patients. We also found that leptin potently induces invasion of endometrial cancer cells in a Matrigel invasion assay. Leptin-stimulated invasion was effectively blocked by pharmacological inhibitors of JAK/STAT (AG490) and phosphatidylinositol 3-kinase (LY294002). Taken together these data indicate that leptin promotes endometrial cancer growth and invasiveness and implicate the JAK/STAT and AKT pathways as critical mediators of leptin action. Our findings have potential clinical implications for endometrial cancer progression in obese patients.
p53 and breast cancer, an update
Authors: Lacroix Marc , Toillon Robert-Alain , Leclercq Guy
Published: May 2006

p53 plays a key role in mediating cell response to various stresses, mainly by inducing or repressing a number of genes involved in cell cycle arrest, senescence, apoptosis, DNA repair, and angiogenesis. According to this important function, p53 activity is controlled in a very complex manner, including several auto-regulatory loops, through the intervention of dozens of modulator proteins (the ‘p53 interactome’). p53 mutations are observed in a significant minority of breast tumours. In the remaining cases, alterations of interactome components or target genes could contribute, to some extent, to reduce the ability of p53 to efficiently manage stress events. While the prognostic and predictive value of p53 is still debated, there is an increasing interest for p53-based therapies. The present paper aims to provide updated information on p53 regulation and function, with specific interest on its role in breast cancer.
The emerging roles of DNA methylation in the clinical management of prostate cancer
Authors: Perry Antoinette S , Foley Ruth , Woodson Karen , Lawler Mark
Published: May 2006

Aberrant DNA methylation is one of the hallmarks of carcinogenesis and has been recognized in cancer cells for more than 20 years. The role of DNA methylation in malignant transformation of the prostate has been intensely studied, from its contribution to the early stages of tumour development to the advanced stages of androgen independence. The most significant advances have involved the discovery of numerous targets such as GSTP1, Ras-association domain family 1A (RASSF1A) and retinoic acid receptor β2 (RARβ2) that become inactivated through promoter hypermethylation during the course of disease initiation and progression. This has provided the basis for translational research into methylation biomarkers for early detection and prognosis of prostate cancer. Investigations into the causes of these methylation events have yielded little definitive data. Aberrant hypomethylation and how it impacts upon prostate cancer has been less well studied. Herein we discuss the major developments in the fields of prostate cancer and DNA methylation, and how this epigenetic modification can be harnessed to address some of the key issues impeding the successful clinical management of prostate cancer.
Insulin-like growth factor (IGF)-I, IGF binding protein-3, and breast cancer risk: eight years on
Authors: Renehan Andrew G , Harvie Michelle , Howell Anthony
Published: May 2006

Insulin-like growth factor (IGF)-I, and its main binding protein, IGFBP-3, are multi-functional regulatory peptides of cell growth and survival, attributes important for tumourigenesis. Following seminal work published in 1998, it has been hypothesised that circulating concentrations of these growth factors may be associated with cancer risk. Systematic reviews have reported that high normal range circulating levels of total IGF-I predict for pre- but not post-menopausal breast cancer. By contrast, associations with circulating IGFBP-3 have been inconsistent. A cumulative meta-analysis demonstrates that earlier reported positive associations between IGFBP-3 and pre-menopausal breast cancer risk now seem less clear as large-size cohorts are published. The reasons are complex and include differences in study design, lack of standardisation between assays, and variations in IGFBP-3 proteolytic activity – these are discussed in this commentary.
Statins reduce human blood–brain barrier permeability and restrict leukocyte migration: Relevance to multiple sclerosis
Authors: Ifergan Igal , Wosik Karolina , Cayrol Romain , Kébir Hania , Auger Chantale , Bernard Monique , Bouthillier Alain , Moumdjian Robert , Duquette Pierre , Prat Alexandre
Published: May 2006

Objective

Dysregulation of the blood–brain barrier (BBB) and transendothelial migration of immune cells are among the earliest central nervous system changes partaking in lesion formation in both multiple sclerosis (MS) and its early clinical form, the clinically isolated syndrome. Evidence for the anti‐inflammatory effects of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitors within the central nervous system arose from studies demonstrating that statins improve clinical signs in the animal model of MS and reduce the number of gadolinium‐enhancing lesions in MS.

Methods

We sought to describe the impact of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitor treatment on the physiology and immunology of human BBB‐derived endothelial cells (ECs).

Results

We demonstrate that lovastatin and simvastatin induce a 50 to 60% reduction in the diffusion rates of bovine serum albumin and [14C]‐sucrose across human BBB‐ECs in vitro through abrogation of isoprenylation processes, but independent of the expression of the tight junction molecules occludin, VE‐cadherin, JAM‐1, zonula occluden‐1, and zonula occluden‐2. Simvastatin and lovastatin were equipotent in reducing BBB permeability in vitro, with median effective concentration (EC50) of 9.5 × 10−8 and 1.0 × 10−7M, respectively. We further demonstrate that lovastatin and simvastatin treatment of BBB‐ECs significantly restricts the migration of clinically isolated syndrome–derived and MS‐derived monocytes and lymphocytes across the human BBB in vitro, through a specific reduction in the secretion of the chemokines monocyte chemotactic protein‐1/CCL2 and interferon‐γ–inducible protein‐10/CXCL10 by BBB‐ECs.

Interpretation

Our data parallel the previously reported magnetic resonance imaging–based radiological findings and suggest an effect of statins that could be beneficial in early MS, restricting the diffusion of molecular tracers and the migration of immune cells across the human BBB. Ann Neurol 2006
Titelbild: Identification of Pyridinylpyrimidines as Inhibitors of Human Methionine Aminopeptidases (Angew. Chem. 23/2006)
Authors: Hu Xiaoyi , Addlagatta Anthony , Matthews Brian W. , Liu Jun O.
Published: May 2006

Evolutionär konservierte Enzyme , die Methionin‐Aminopeptidasen (MetAPs), entfernen N‐terminale Methioninreste bei der Proteinsynthese. J. O. Liu et al. beschreiben in ihrer Zuschrift auf S. 3856 ff. eine neue Klasse von MetAP‐Inhibitoren sowie die Kristallstruktur eines Inhibitor‐MetAP1‐Komplexes. Diese Ergebnisse erleichtern die Entwicklung weiterer MetAP1‐spezifischer Inhibitoren, die als molekulare Sonden der MetAP1‐Funktion und als Leitstrukturen für Inhibitoren des Krebszellwachstums dienen können.
Cover Picture: Identification of Pyridinylpyrimidines as Inhibitors of Human Methionine Aminopeptidases (Angew. Chem. Int. Ed. 23/2006)
Authors: Hu Xiaoyi , Addlagatta Anthony , Matthews Brian W. , Liu Jun O.
Published: May 2006

The evolutionarily conserved enzymes, the methionine aminopeptidases (MetAPs), remove N‐terminal methionine during protein synthesis. J. O. Liu et al. describe in their Communication on page 3772 ff. a new class of inhibitors for MetAPs and the crystal structure of the inhibitor complexed with MetAP1. These findings should facilitate the development of MetAP1‐specific inhibitors that can serve as molecular probes for the function of MetAP1 and as potential leads for inhibitors of cancer cell growth.
Modeling of polymer/clay nanocomposite formation
Authors: Kim Younghoon , White James L.
Published: May 2006

A statistical thermodynamic modeling of the formation of polymer/clay intercalation and nanocomposites was developed. The key factor in determining intercalation was an exothermic heat of mixing between polymer chains and the organically modified silicate surface. This was found to agree with previous experimental results in the literature including halogenated polymers and acrylonitrile copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1657–1663, 2006
Preparation of biodegradable crosslinking agents and application in PVP hydrogel
Authors: Jiao Yanpeng , Liu Zonghua , Ding Shan , Li Lihua , Zhou Changren
Published: May 2006

Firstly, biodegradable crosslinking agents (BCA) were synthesized by ring‐opening polymerization reaction of lactide, four kinds of which with different molecular weights were got by means of changing the ratio of DL‐lactide(LA) and glycerol(GL). Then a series of poly(N‐vinyl pyrrolidone) (PVP) hydrogels were prepared successfully by radical polymerization of BCA and N‐vinyl pyrrolidone(NVP). Both the ratio of NVP/BCA and the molecular weight of BCA were used to control the performance of PVP hydrogels, which were measured in terms of the ratio of swelling, contact angle, mechanical properties, and biodegradability in vitro. This study showed that increasing both the ratio of NVP/BCA and the molecular weight of BCA resulted in a low crosslinking density of the hydrogels. The crosslinking density played an important role in determining the properties of biodegradable PVP hydrogels. Both the ratio of NVP/BCA and the molecular weight of BCA contributed to high ratio of swelling. A smaller amount of crosslinking agent caused a lower contact angle, while the molecular weight of BCA had little effect on it. In terms of mechanics of hydrogels on both dry and wet conditions, tensile modulus decreased along with decreasing BCA, while the extension at break increased at the beginning and decreased at the end. In the end, measured by mass loss, biodegradability in vitro of hydrogels had two stages: an initial stage with approximately constant loss of mass (stage 1) followed by a stage with rapid mass loss (stage 2). Both increased content and molecular weight of BCA improved the degradation rate of the hydrogels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1515–1521, 2006
Waste polyvinyl chloride‐modified bitumen
Authors: Abdel‐Goad Mahmoud A‐Halim
Published: May 2006

Polyvinyl chloride (PVC) pipe wastes have been employed as a soft filler up to a level of 11 wt % in making bituminous products for paving applications. The PVC wastes were homogenously mixed with bitumen in the molten state. The viscoelastic properties of the bitumen blends such as storage modulus, loss modulus, and dynamic viscosity were studied and compared with those of neat bitumen. These properties were studied using an ARES‐Rheometer (Rheometric Scientific, Co.) under nitrogen atmosphere. The results indicate that the incorporation of the waste PVC into bitumen enhances the dynamic mechanical moduli and viscosity of the bitumen. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1501–1505, 2006
Studies of poly(8‐hydroxy‐4‐azoquinolinephenol‐formaldehyde) and its metal complexes
Authors: Vijayalakshmi S. , Subramanian S. , Rajagopan S. , Kaliyappan T.
Published: May 2006

Poly(8‐hydroxy‐4‐azoquinolinephenol‐formaldehyde) resin (8H4AQPF) was prepared by condensing 8‐hydroxy 4‐azoquinoline phenol with formaldehyde (1 : 1 mol ratio) in the presence of oxalic acid. Polychelates were obtained when the DMF solution of poly(8H4AQPF) containing a few drops of ammonia was treated with the aqueous solution of Cu(II) and Ni(II) ions. The polymeric resin and polymer–metal complexes were characterized with elemental analysis and spectral studies. The elemental analysis of the polymer–metal complexes suggested that the metal‐to‐ligand ratio was 1 : 2. The IR spectral data of the polychelates indicated that the metals were coordinated through the nitrogen and oxygen of the phenolic OH group. Diffuse reflectance spectra, electron paramagnetic resonance, and magnetic moment studies revealed that the polymer–metal complexes of the Cu(II) complexes were square planar and those of the Ni(II) complexes were octahedral. X‐ray diffraction studies revealed that the polymer metal complexes were crystalline. The thermal properties of the polymer and polymer–metal complexes were also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1506–1510, 2006
Synthesis of poly(ester sulfoimide) from dichlorocarbonylimide of disaccharindicarboxylic acid and aromatic diols
Authors: Aslanov T. A. , Salakhov M. S. , Efendiev A. A.
Published: May 2006

A new chlorocarbonylimide of disaccharindicarboxylic acid was synthesized by condensation of imides of saccharin‐6‐carboxylic acid with alkyl‐ and alkylaryl bishalogenides. Poly(ester sulfoimide), soluble in organic solvents, was synthesized by polycondensation of chlorocarbonylimide with bisphenol. DTA and TGA investigations have shown that poly(ester sulfoimide)s were stable at temperatures up to 300°C–345°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1687–1691, 2006
Structure and properties of polymer–wood composites based on an aliphatic copolyamide and secondary polyethylenes
Authors: Mamunya Y. , Zanoaga M. , Myshak V. , Tanasa F. , Lebedev E. , Grigoras C. , Semynog V.
Published: May 2006

Composite materials based on an aliphatic copolyamide and a secondary polyethylene, as thermoplastic matrices, and wood chips as filler were obtained and characterized. The influence of different factors (polymeric matrix type, fractional composition and geometrical characteristics of wood filler, processing parameters and ratio polymer/wood) on the properties of polymer–wood composites (PWCs) was studied. It was demonstrated that the packing factor F has an essential influence on the properties of PWCs: increasing F values determines an improvement in mechanical properties of these materials. Mechanical properties, thermal behaviour, morphological and diffusion characteristics of the analyzed composites were evaluated through specific methods and reported herein. Morphological and DSC data confirmed the presence of strong interface interactions between polymer and wood. The diffusion characteristics of PWCs showed that the diffusion coefficient D essentially depends on filler content in composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1700–1710, 2006
Surface‐modified polysulfone membranes: Aqueous phase oxidation via persulfate radical
Authors: Dal‐Cin Mauro M. , Guiver Michael D. , Striez Carolyn N. , Carlsson Dave J. , Kumar Ashwani
Published: May 2006

Polysulfone (Udel P1800) ultrafiltration membranes were surface modified using potassium persulfate (K2S2O8) as a free radical source in the aqueous phase. The expected modification was hydrogen abstraction leading to hydroxylation at one or two sites on the isopropylidene linkage. Reaction time, K2S2O8 concentration, and temperature were optimized based on two criteria: (1) minimal change in pure water fluxes after surface modification and (2) reduction of adsorptive fouling with a pulp mill effluent. The pure water flux retention for an unmodified membrane was ∼20% after adsorptive fouling with the pulp mill effluent and was increased to 70% after reaction with K2S2O8. Angle‐resolved XPS indicated increased oxygen and a new carbon peak consistent with an aldehyde reaction occurring in the top 3.5 nm. NMR solution analysis was inconclusive because of the low sensitivity of the experiment. Further analysis of oxidation products was carried out on finely dispersed polymer. Fourier transform infrared, internal reflection spectroscopy suggested oxidation by the formation of an aldehyde which was further oxidized to carboxylic acid. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1723–1730, 2006
Application of Fourier transform infrared spectroscopy in the study of interactions between PVC and plasticizers: PVC/plasticizer compatibility versus chemical structure of plasticizer
Authors: González N. , Fernández‐Berridi M. J.
Published: May 2006

Fourier transform infrared spectroscopy is applied in the study of interactions between PVC resin and plasticizers in flexible PVC systems. The comparison of the theoretical infrared spectra coming from the addition of the respective component infrared spectra with those of PVC/plasticizer experimental systems gives information about polymer/plasticizer interaction degree. In addition, solvation capacity of the plasticizer varies as a function of its chemical structure, giving rise to compatibility differences between the system components. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1731–1737, 2006
Synthesis, characterization, and pressure‐sensitive properties of butyl acrylate and methyl acrylate copolymers
Authors: Wang Chiliang , Wang Li , Chen Chang , Chen Tao , Jiang Guohua
Published: May 2006

Butyl acrylate and methyl acrylate copolymers were prepared and evaluated as pressure‐sensitive adhesives. The effects of polymerization conditions such as the temperature, time, amounts of the monomers, and feeding method on the molecular weight, molecular weight distribution, and composition of the resultant copolymers were investigated. The adhesive properties were evaluated in terms of the viscosity, peel strength, and hold time. The best molar ratio of methyl acrylate in the copolymer was 0.466 for pressure‐sensitive adhesives. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1535–1542, 2006
Catalytic effect of 2,2′‐diallyl bisphenol A on thermal curing of cyanate esters
Authors: Koh Henry C. Y. , Dai Jie , Tan Eileen , Liang Weirong
Published: May 2006

Cyanate esters are a class of thermal resistant polymers widely used as thermal resistant and electrical insulating materials for electric devices and structural composite applications. In this article, the effect of 2,2′‐diallyl bisphenol A (DBA) on catalyzing the thermal curing of cyanate ester resins was studied. The curing behavior, thermal resistance, and thermal mechanical properties of these DBA catalyzed cyanate ester resins were characterized. The results show that DBA is especially suitable for catalyzing the polymerization of the novolac cyanate ester resin (HF‐5), as it acts as both the curing catalyst through depressing the exothermic peak temperature (Texo) by nearly 100°C and the toughening agent of the novolac cyanate ester resin by slightly reducing the elastic modulus at the glassy state. The thermogravimetric analysis and dynamic mechanical thermal analysis show that the 5 wt % DBA‐catalyzed novolac cyanate ester resin exhibits good thermal resistance with Td5 of 410°C and the char yield at 900°C of 58% and can retain its mechanical strength up to 250°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1775–1786, 2006
1‐(bromoacetyl)pyrene and its arsonium salt as novel photoinitiators for styrene polymerization
Authors: Mishra Anuradha , Daswal Swati
Published: May 2006

The photopolymerization of styrene (Sty) in DMSO induced by pyrene (Py), 1‐Acetylpyrene (AP), 1‐(Bromoacetyl) pyrene (BP), and 1‐Acetylpyrene triphenyl arsonium bromide (APAS) has been investigated. Under all conditions employed, Py was completely ineffective. Incorporation of a chromophoric (COCH3) moiety introduces photoinitiating activity into Py. It was observed that introduction of Br into AP markedly accelerated the rate of UV irradiation‐induced polymerization. BP was further modified to its arsonium salt (APAS). The kinetics and mechanism of polymerization using BP and APAS as initiators have been investigated in detail. The polymerization with BP followed nonideal kinetics (Rp ∝ [BP]0.8 [Sty]1.1) with respect to initiator concentration whereas ideal kinetics (Rp ∝ [APAS]0.48 [Sty]1.1) was observed when APAS was used as initiator. Degradative transfer is thought to be mainly responsible for this unusual kinetic behavior for BP–Sty system. The kinetic data proved that BP was more effective and faster initiator than APAS. In both the cases, the mechanism of polymerization was free radical as evident by inhibiting the effect of hydroquinone and ESR studies. IR and NMR spectra showed the atactic nature of polystyrene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1793–1798, 2006
Dynamic mechanical and thermal properties of plasticized poly(lactic acid)
Authors: Ren Zhongjie , Dong Lisong , Yang Yuming
Published: May 2006

The blends of low molecular weight triacetin (TAC) and oligomeric poly(1,3‐butylene glycol adipate) (PBGA) were used as multiple plasticizers to lubricate poly(lactic acid) (PLA) in this study. The thermal and mechanical properties of plasticized polymers were investigated by means of dynamic mechanical analysis and differential scanning calorimetry. Atomic force microscopy (AFM) was used to analyze the morphologies of the blends. Multiple plasticizers were effective in lowering the glass transition temperature (Tg) and the melting temperature (Tm) of PLA. Moreover, crystallinity of PLA increased with increasing the content of multiple plasticizers. Tensile strength of the blends decreased following the increasing of the plasticizers, but increased in elongation at break. AFM topographic images showed that the multiple plasticizers dispersed between interfibrillar regions. Moreover, the fibrillar crystallite formed the quasicrosslinkings, which is another cause for the increase in elongation at break. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1583–1590, 2006
Modification of polyethersulphone induced by high energy proton, C+, and Ne6+ ions: A spectroscopic study
Authors: Vinodh Kumar S. , Ghadei B. , Jal P. K. , Dey K. , Krishna J. B. M. , Saha A.
Published: May 2006

Polyethersulphone (PES) was irradiated with 4 MeV proton, 3.6 MeV C+, and 145 MeV Ne6+ ions at different ion fluences. The linear energy transfer dependence on ion‐induced spectral changes was analyzed by ultraviolet–visible, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The gradual red shift with the increase in optical absorption was observed in the region of 350–500 nm for proton and 400–800 nm for C+ and Ne6+ ions irradiated PES. The gradual shift in absorption may be attributed to the formation of carbonaceous clusters. The gradual decrease in optical band gap indicates increase in cluster sizes. When PES was irradiated with protons, loss in fluorescence emission intensity at 440 nm was observed, although there was no change in spectral shape. In contrast, C+ and Ne6+ ion irradiated PES showed blue shift with concomitant loss in intensity and the formation of new peak at 575 nm. In fact, heavier ions are found to be more effective in inducing physicochemical modifications in PES. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1591–1597, 2006
ATRP of acrylonitrile catalyzed by FeCl2/succinic acid under microwave irradiation
Authors: Hou Chen , Qu Rongjun , Ji Chunnuan , Wang Chunhua , Sun Changmei
Published: May 2006

A single‐pot atom‐transfer radical polymerization (ATRP) under microwave irradiation was first used to successfully synthesize polyacrylonitrile. This was achieved by using FeCl2/succinic acid as the catalyst and 2‐chloropropionitrile as the initiator. Using the same experimental conditions, the apparent rate constant under microwave irradiation was found to be higher than that under conventional heating. The FeCl2/succinic acid ratio of 1 : 2 not only gives the best control of molecular weight and its distribution but also provides rather rapid reaction rate. When FeCl2 was replaced with CuCl, ATRP of AN does not show an obvious living characteristics. To demonstrate the active nature of the polymer chain end, the polymers were used as macroinitiators to proceed the chain‐extension polymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1598–1601, 2006
Partial exfoliation and layer expansion of vermiculite layer in solid state by solid state shear milling (S3M) method
Authors: Shao Weiguo , Wang Qi
Published: May 2006

A new method, solid state shear milling (S3M), was reported for realizing the exfoliation and layer expansion of vermiculite layer in solid state by using pan‐mill equipment, which can exert fairly strong squeezing force and shearing force on milled materials. The mechanism was discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1806–1809, 2006
Modeling heat and degree of gelation for methyl cellulose hydrogels with NaCl additives
Authors: Joshi S. C. , Lam Y. C.
Published: May 2006

Methyl cellulose (MC) hydrogels are thermoreversible physical hydrogels and their gelation is an endothermic process. A model consisting of a generalized expression for two bell‐shape curves was formulated to describe and capture enthalpy changes that take place during the gelation of an aqueous solution of MC, SM4000, in the presence of sodium chloride, NaCl, in different concentrations. The procedure followed in obtaining the necessary constants for the model using the differential scanning calorimetric (DSC) measurements is elaborated. The developed model described the salt‐out effects of NaCl in various % on the MC gelation very well. One of the two bell‐shape curves mapped most part of the DSC thermograms. The secondary bell‐shape curves portrayed the minor enthalpy changes. The possible mechanisms and molecular bonding processes driven by the energy represented by the area under these two individual curves are discussed. Subsequently, a sigmoidal growth model for the degree of gelation was introduced, and its development is explained in the paper. The import of various constants for these two models, the bell‐shape curves and the sigmoidal growth models, in terms of gelation kinetics is identified. The need for a specific term of the sigmoidal model for depicting the effect of the salt additive onto the gelation is recognized. The comparison between the results obtained using these two models is discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1620–1629, 2006
Preparation and characterization of composites: Ethylene–propylene–diene terpolymer‐graft‐maleic anhydride/CaCO3
Authors: Zhang Jun , Ding Qing‐Jun , Hu Bai‐Xing , Liu Bao‐Lei , Shen Jian
Published: May 2006

In this paper, a new method was applied to form crosslinking networks in the ethylene–propylene–diene terpolymer (EPDM) matrix with calcium carbonate(CaCO3) particles, which were chemically treated by maleic anhydride (MAH). The tensile test showed that the tensile strength and the elongation at break of the composites were improved significantly, and when the content of CaCO3 was about 20 wt % in the composites, the maximum tensile properties were achieved. The results of swell and solution text showed that the composites had evident crosslinking structure. The results of attenuated transmission reflectance‐Fourier transform infrared (ATR‐FTIR) spectrum proved that the Acid‐Base reaction between CaCO3 and MAH had happened. SEM micrographs showed that the interfacial adhesion between CaCO3 and copolymer was well. The thermogravimetric analysis curves showed that the composites had a new change in mass between 655 and 700°C, which might be the decomposition temperature of calcium maleicate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1810–1815, 2006
A novel feed‐stock recyclable hyperbranched polymaleimide: Synthesis and characterization
Authors: Pan Wanjiang , Liu Hewen , Wu Songtao , Wilén Carl‐Eric
Published: May 2006

Hyperbranched polymaleimide can be readily obtained by copolymerization of allyl maleimide and propyl maleimide. A hyperbranched polymaleimide was obtained in a yield of 56 wt % in 3 h at 50°C, whose weight average molecular mass and polydispersity index were measured by size‐exclusion chromatography to be 59,000 and 4.1, respectively. TGA showed a one‐step mass loss process in the decomposition of the hyperbranched polymaleimide. The dominant pyrolysis mechanism was revealed by gas chromatography/mass spectrometry to be depolymerization. The major pyrolysates of the hyperbranched polymaleimide were allyl maleimide, propyl succinimide, and other volatile monomeric units. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1848–1852, 2006
Mechanical properties of blocked polyurethane/epoxy interpenetrating polymer networks
Authors: Chen Chin‐Hsing , Sun Yun‐Yun
Published: May 2006

The mechanical properties of blocked polyurethane(PU)/epoxy interpenetrating polymer networks (IPNs) were studied by means of their static and damping properties. The studies of static mechanical properties of IPNs are based on tensile properties, flexural properties, hardness, and impact method. Results show that the tensile strength, flexural strength, tensile modulus, flexural modulus, and hardness of IPNs decreased with increase in blocked PU content. The impact strength of IPNs increased with increase in blocked PU content. It shows that the tensile strength, flexural strength, tensile modulus, and flexural modulus of IPNs increased with filler (CaCO3) content to a maximum value at 5, 10, 20, and 25 phr, respectively, and then decreased. The higher the filler content, the greater the hardness of IPNs and the lower the notched Izod impact strength of IPNs. The glass transition temperatures (Tg) of IPNs were shifted inwardly compared with those of blocked PU and epoxy, which indicated that the blocked PU/epoxy IPNs showed excellent compatibility. Meanwhile, the Tg was shifted to a higher temperature with increasing filler (CaCO3) content. The dynamic storage modulus (E′) of IPNs increased with increase in epoxy and filler content. The higher the blocked PU content, the greater the swelling ratio of IPNs and the lower the density of IPNs. The higher the filler (CaCO3) content, the greater the density of IPNs, and the lower the swelling ratio of IPNs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1826–1832, 2006
Properties of composite laminated material produced with layers of beech and paperboard made from waste paper
Authors: Celebi Gulser , Cemil Ilce Abdullah , Kilic Murat , Ozkaya Kadir
Published: May 2006

One of the basic principles for sustainable development is to prevent wasting resources, preserve natural resources, and recycle the products obtained from resources. For this study, paperboard obtained from waste paper was laminated with natural wooden layers in accordance with the order of beech‐paperboard‐beech‐paperboard‐beech and an alternate material was produced. In this context, experiments were made for determining the specific gravity, compression, shearing, bending strength, elasticity module, and the resistance to direct withdrawal of screws and nails on a radial section surface with the objective of determining the usability of this material as a building material. When the findings obtained at the end of the experiments are studied carefully in a comparative manner, it was observed that paperboard laminated materials could be used with different objectives in interiors to protect against humidity. It was determined that it could be used in place of solid poplar materials for places of use where resistance to compression, elasticity module, and resistance to direct withdrawal of screws and nails on a radial section surface are important and in places where resistance to bending and shearing is required after taking the necessary measures. In the end, a contribution to the literature was provided by researching possibilities for different use of a material regained from waste and to provide sustainability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1943–1952, 2006
The effect of cooling rate on the impact performance and dynamic mechanical properties of rotationally molded metallocene catalyzed linear low density polyethylene
Authors: Therese Pick Louise , Harkin‐Jones Eileen , Jovita Oliveira Maria , Clara Cramez Maria
Published: May 2006

This article examines changes to the morphology of rotationally molded metallocene catalyzed linear low density polyethylene brought about by varying the cooling rate during processing. These changes in morphology lead to variations in the impact performance, which is reflected in the dynamic mechanical characteristics of the materials. Various analytical techniques are used in an attempt to explain the differences in impact behavior. Slow cooling is shown to result in high crystallinity, and in the formation of large spherulites, which in turn is detrimental to the impact performance of the material, particularly at low temperatures. The high crystallinity corresponds with a shift in the β transition of the material to a higher temperature, and is shown to result in a higher brittle–ductile transition. A case study was also carried out on samples from a finished part provided by an industrial molder, one section of which failed in a brittle manner when impact tested while the other failed in a ductile manner. Microscopy results showed that the brittle material had large spherulites at the inside surface, while the ductile material showed incipient degradation at this surface, which has previously been shown to be of benefit to impact strength in rotationally molded parts. Dynamic mechanical studies again showed a β transition at a higher temperature in the brittle samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1963–1971, 2006
Toughening of wood particle composites—Effects of sisal fibers
Authors: Nuñez Adrián J. , Aranguren Mirta I. , Berglund Lars A.
Published: May 2006

Sisal fibers were added to wood particle composites to enhance their toughness. The selected matrix was a commercial styrene diluted unsaturated polyester thermoset resin. Fracture tests were carried out using single‐edge notched beam geometries. Stiffness, strength, critical stress intensity factor KIQ, and work of fracture Wf of notched specimens were determined. The incorporation of sisal fibers into wood particle composites significantly changed the fracture mode of the resulting hybrid composite. For the neat matrix and the wood particle composites, once the maximum load was reached, the crack propagated in a catastrophic way. For hybrid composites, fiber bridging and pull‐out were the mechanisms causing increased crack growth resistance. Addition of a 7% wt of sisal fibers almost doubled the KIQ value of a composite containing 12% wt of woodflour. Moreover, the Wf increased almost 10‐fold, for the same sample. In general, the two composite toughness parameters KIQ and Wf increased when the fraction of sisal fibers was increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1982–1987, 2006
Synthesis and characterization of new cardo poly(bisbenzothiazole)s from 1,1‐bis(4‐amino‐3‐mercaptophenyl)‐4‐tert‐butylcyclohexane dihydrochloride
Authors: Huang Wei , Xu Hongjie , Yin Jie
Published: May 2006

A new monomer 1,1‐bis(4‐amino‐3‐mercaptophenyl)‐4‐tert‐butylcyclohexane dihydrochloride, bearing the bulky pendant 4‐tert‐butylcyclohexylidene group, was synthesized from 4‐tert‐butylcyclohexanone in three steps. Its chemical structure was characterized by 1H NMR, 13C NMR, MS, FTIR, and EA. Aromatic poly(bisbenzothiazole)s (PBTs V) were prepared from the new monomer and five aromatic dicarboxylic acids by direct polycondensation. The inherent viscosities were in the range of 0.63–2.17 dL/g. These polymers exhibited good solubility and thermal stability. Most of the prepared PBTs V were soluble in various polar solvents. Thermogravimetric analysis showed the decomposition temperatures at 10% weight loss that were in the range of 495–534°C in nitrogen. All the PBTs V, characterized by X‐ray diffraction, were amorphous. The UV absorption spectra of PBTs V showed a range of λmax from 334 to 394 nm. All the PBTs V prepared had evident fluorescence emission peaks, ranging from 423 to 475 nm with different intensity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2000–2008, 2006
Curing of phenolic resins modified with chestnut tannin extract
Authors: Peña C. , Martin M. D. , Tejado A. , Labidi J. , Echeverria J. M. , Mondragon I.
Published: May 2006

Phenolic novolac resins have been modified with chestnut tannin for reduction of phenol content in resins. In this work, rheological and kinetic analysis of curing reactions of these resins with hexamethylenetetramine (hexamine) has been performed. Chemical structure of obtained materials has been analyzed and compared with that of nonmodified resins. Results reveal that cure reactions of resin modified with chestnut tannin are different when compared with nonmodified novolacs not only in the cure kinetics values but also in final chemical structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2034–2039, 2006
Preparation and thermal stability of new cellulose‐based poly(propylene imine) and poly(amido amine) hyperbranched derivatives
Authors: Hassan Mohammad L.
Published: May 2006

New cellulose‐based hyperbranched derivatives having different degrees of branching were prepared via reaction of cellulose with acrylonitrile followed by reduction of nitrile groups and successive reaction with acrylonitrile or methylacrylate. First‐ (G = 1) and half‐ (G = 0.5) generation cellulose‐based hyperbranched poly(propylene imine) or poly(amido amine) derivatives have been prepared with high reaction yield. The structure of the prepared derivatives was confirmed by Fourier transform infrared and 13C nuclear magnetic resonance (13C NMR). Thermal stability of the different cellulose‐based hyperbranched derivatives were examined using thermogravimetric analysis to study the effect of branching on the thermal decomposition parameters. The onset degradation temperature and the activation energy of the thermal degradation decreased with increasing the branching of the cellulose‐based hyperbranched derivatives. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2079–2087, 2006
Synthesis of polyaniline/MCM‐41 composite through surface polymerization of aniline
Authors: Feng Xiaomiao , Yang Gang , Liu Yuge , Hou Wenhua , Zhu Jun‐Jie
Published: May 2006

Polyaniline (PANI)/porous silica MCM‐41 (MCM‐41) composite was synthesized according to surface polymerization theory, and it was confirmed through comparing with PANI/solid silica (SiO2) by TGA and XPS techniques. The morphology and composition of the composite were also characterized by some techniques such as small‐angle XRD, N2‐adsorption isotherm, SEM, FTIR, and UV–vis. The thermal stability for the PANI/MCM‐41 composite was enhanced when compared with that of pure PANI. With the increase in the concentration of HCl, the doping degree increased and UV‐absorption peak at about 700 nm showed a red shift. The conductivity of the composite was enhanced by increasing the concentration of HCl. The results of FTIR showed that there was a strong interaction between PANI and MCM‐41. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2088–2094, 2006
Copolymerization kinetics of acrylonitrile with amino ethyl‐2‐methyl propenoate in H2O/DMSO mixture
Authors: Hou Chen , Qu Rongjun , Ji Chunnuan , Wang Chunhua , Sun Changmei , Zhang Chuntao
Published: May 2006

Amino ethyl‐2‐methyl propenoate (AEMP) was used successfully to copolymerize with acrylonitrile (AN). This was achieved by using azobisisobutyronitrile as the initiator. Kinetics of copolymerization of AN with AEMP was investigated in H2O/dimethylsulfoxide (DMSO) mixture between 50 and 70 °C under N2 atmosphere. The rate of copolymerization was measured. The kinetic equation of copolymerization system was obtained and the overall activation energy for the copolymerization system was determined. Values of monomer apparent reactivity ratios were calculated using Kelen–Tudos method. It has been found that the apparent reactivity ratios in aqueous suspension polymerization system are similar to those in solution polymerization system at polymerization conversion less than 25%. At conversion beyond 45%, the changes of monomer apparent reactivity ratios become less prominent. In water‐rich reaction medium (H2O/DMSO > 70/30), monomer apparent reactivity ratios are approximately equivalent to those in aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H2O > 70/30), apparent reactivity ratios are similar to those in solution polymerization system. With an increase of polarity of solvent, values of apparent reaction ratios both decrease. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2095–2100, 2006
Effects of in situ biomineralization on microstructural and mechanical properties of hydroxyapatite/polyethylene composites
Authors: Huang Suping , Zhou Kechao , Zhu Wu , Huang Baiyun , Li Zhiyou
Published: May 2006

To improve the mechanical properties of hydroxyapatite (Ca10(PO4)6(OH)2; HAP)/High‐density polyethylene (HDPE) composites, the process of in situ biomineralization was used, and its effect on the microstructure and mechanical properties of HAP/HDPE composite was investigated by means of Fourier transform infrared spectroscopy, energy dispersive X‐ray analysis, scanning electron microscope, Instron testing machine, and Ceast Impact tester at room temperature. Results show that: (1) the HAP/HDPE composite prepared by in situ biomineralization has the better mechanical properties. The impact strength and the tensile strength reach 712 J/m and 96 MPa, respectively, which were more than three times higher than those of composites prepared by blending directly. (2) The biomineralized HAP crystals grew onto the HDPE with chemical bond and dispersed in HDPE polymer on the level of nanometer dimension, which provided a greater surface area for bonding with the polymer, accordingly enhancing the interfacial bonding strength. On the other hand, the higher interfacial bonding strength will produce interfacial stress from the contraction of matrix, which can strain‐induce the crystallization of matrix to form the extended‐chain crystal structure in the area surrounding the filler. As a result, the mechanical properties of composite improved greatly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1842–1847, 2006
Synthesis and phase separation of poly(N‐isopropyl acrylamide‐co‐methoxy polyethyleneglycol monomethacrylate)
Authors: Kim Youn C. , Kil Deog‐Soo , Kim Jin C.
Published: May 2006

The poly(N‐isopropyl acrylamide‐co‐methoxy polyethyleneglycol monomethacrylate, NIPAM‐co‐MPEG) with different length of ethylene oxide (EO) were synthesized from their monomers, NIPAM and MPEGs. The numbers of repeating units of EO were 6, 10, 24, and 46. The chemical structure and mole ratio of the monomers was determined by Fourier transform infrared (FTIR), 1H‐NMR, and 13C‐NMR spectroscopy. The d‐spacing increased with the number of EO and the values of the copolymers were in the range of 0.437–0.452 nm. The lower critical solution temperature of the poly(NIPAM‐co‐MPEG) shifted to higher temperature as the number of EO and the amount of MPEG increased. The change of chemical shift for methoxy proton in MPEG exhibited a larger than those of the other protons of the poly(NIPAM‐co10−2MPEG). Activation energy (Ea) for methoxy proton in MPEG showed a larger value than that of the methyl proton in NIPAM. These NMR results indicate the fact that more significant conformational transformations occur in the methoxy group through the phase separation than in the methyl group in NIPAM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1833–1841, 2006
Effect of pretreatment with detergent on mechanical properties of photocured coir (Cocos nucifera) fiber with ethyleneglycol dimethacrylate
Authors: Khan Mubarak A. , Bhattacharia S. K. , Hassan M. Masudul , Sultana Abeda
Published: May 2006

Coir fibers were treated with ethylene glycol dimethacrylate (EGDMA) mixed with methanol (MeOH) under UV radiation. A series of solutions of different concentrations of EGDMA in methanol along with a photoinitator, Irgacure‐500 (mixture of 1‐hydroxylcyclohexylphenylketone and benzophenonc), were prepared. Monomer concentration, soaking time, and radiation intensity were optimized in terms of polymer loading (PL) and mechanical properties. EGDMA (50%), 5 min soaking time at the 4th pass of radiation, produced higher PL and tensile strength (TS), and the values of PL is 17% and TS is 1.3 times of the nontreated one. Then, coir fiber was pretreated with detergent and then treated with the optimized monomer formulation, which exhibited a higher PL of 69% and produced TS of the coir fiber of 4.4 times of the nontreated one. Coir fiber pretreated with detergent along with UV radiation showed the highest TS, which is 18.2 times of nontreated one. Water uptake, degradable properties, and simulated weathering of treated and virgin fibers were also monitored, which showed that EGDMA treatment under UV radiation improved the degradable property. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1630–1636, 2006
Systemic lupus erythematosus in a multiethnic US cohort: XXXIV. Deficient mannose‐binding lectin exon 1 polymorphisms are associated with cerebrovascular but not with other arterial thrombotic events
Authors: Calvo‐Alén Jaime , Alarcón Graciela S. , Tew Monty B. , Tan Filemon K. , McGwin Gerald , Fessler Barri J. , Vilá Luis M. , Reveille John D. ,   LUMINA Study Group
Published: May 2006

Objective

To study the association between deficient mannose‐binding lectin (MBL) genotypes and arterial thrombotic events in systemic lupus erythematosus (SLE).

Methods

Patients with SLE of Hispanic, African American, and Caucasian ethnicity from LUMINA (LUpus in MInorities, NAture versus nurture), a multiethnic, longitudinal study of outcome, were studied. Arterial thrombotic events (myocardial infarction, angina, coronary artery bypass graft surgery, stroke, claudication, gangrene, or tissue loss and/or peripheral arterial thrombosis) that occurred after diagnosis were recorded. Genotyping for MBL gene polymorphisms was performed and their distribution was compared between patients who did and did not have thrombotic events.

Results

There were 58 events (21 cardiovascular, 27 cerebrovascular, and 10 peripheral vascular) in 48 patients. Patients who had thrombotic events were older and were more likely to be smokers, to have more severe disease, and to have accrued more damage overall. Also, a larger proportion of these patients had C‐reactive protein values in the highest quintile of distribution. No significant difference in arterial thrombotic events was found in patients homozygous for MBL‐deficient alleles compared with others. Similar results were seen within ethnic groups. Caucasians who developed potential thrombotic events exhibited a higher frequency of MBL‐deficient alleles, but the difference was not statistically significant for all events together or for cardiovascular and cerebrovascular events combined. However, when only the cerebrovascular events were considered, the difference became statistically significant.

Conclusion

Age, smoking, and measures of activity and damage were associated with arterial thrombotic events in patients with SLE, but MBL‐deficient genotypes were not, with cerebrovascular events in Caucasians being the exception. The relationship between MBL‐variant alleles and arterial thrombotic events may exist only within select ethnic groups and event types.