bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer Brushes via Controlled, Surface‐Initiated Atom Transfer Radical Polymerization (ATRP) from Graphene Oxide
Authors: Lee Sun Hwa , Dreyer Daniel R. , An Jinho , Velamakanni Aruna , Piner Richard D. , Park Sungjin , Zhu Yanwu , Kim Sang Ouk , Bielawski Christopher W. , Ruoff Rodney S. 
Published: November 2009

AbstractA method for growing polymers directly from the surface of graphene oxide is demonstrated. The technique involves the covalent attachment of an initiator followed by the polymerization of styrene, methyl methacrylate, or butyl acrylate using atom transfer radical polymerization (ATRP). The resulting materials were characterized using a range of techniques and were found to significantly improve the solubility properties of graphene oxide. The surface‐grown polymers were saponified from the surface and also characterized. Based on these results, the ATRP reactions were determined to proceed in a controlled manner and were found to leave the structure of the graphene oxide largely intact.magnified image
Mathematical Modeling of PAG‐ and NIPAM‐Based Polymer Gel Dosimeters Contaminated by Oxygen and Inhibitor
Authors: Koeva Valeria I. , Daneshvar Shahab , Senden Robert J. , Imam A. H. M. , Schreiner L. John , McAuley Kimberley B. 
Published: November 2009

AbstractA mathematical model for crosslinking copolymerization of acrylamide (or NIPAM) and N,N'‐methylenebisacrylamide is extended to account for contamination by oxygen and the inhibitor MEHQ. This model improves basic understanding of interactions among oxygen, MEHQ and polymerization reactions in gel dosimeters that are used to verify radiation doses delivered by cancer treatment equipment. Improved parameter estimates result in a good match between model predictions and data. The model predicts that a larger absorbed dose will be required to overcome the oxygen inhibition with increasing oxygen contamination, in agreement with experimental data. The model also predicts that MEHQ, in the absence of oxygen, has almost no influence on dosimeter response.magnified image
Investigation of Thermal Expansion of Polyimide/SiO2 Nanocomposites by Molecular Dynamics Simulations
Authors: Komarov Pavel V. , Chiu Yu‐Tsung , Chen Shih‐Ming , Reineker Peter 
Published: November 2009

AbstractIn this paper, an atomistic model for PI/SiO2 hybrid nanocomposites was designed for the investigation of physical properties of this material on the base of molecular dynamics simulations. The thermal properties of a reference pure PI matrix in the temperature range of 300–650 K were first investigated. The results for the CTE and the glass transition temperature showed good agreement with the experimental data. Then, the thermal expansion of the model of PI/silica composite material with different SiO2 fractions was investigated at normal conditions. The CTE of the composite model decreases with the increase in the SiO2 content in agreement with experimental studies. The results show a threshold for the SiO2 loading beyond which the material model exhibits ultra‐low thermal expansion.magnified image
A novel tumor suppressor gene RhoBTB2 (DBC2): Frequent loss of expression in sporadic breast cancer
Authors: Mao Haiting , Qu Xun , Yang Yongmei , Zuo Wenshu , Bi Ye , Zhou Chengjun , Yin Haipeng , Deng Biping , Sun Jintang , Zhang Lining 
Published: November 2009

AbstractRhoBTB2 was isolated recently as a tumor suppressor gene from human chromosome 8p21.3. Although RhoBTB2 was found to be frequently lost in breast cancer lines, expression status of RhoBTB2 in sporadic breast cancer tissues and its clinical and prognostic value, however, remain unclear. Tissue samples from breast cancer patients and normal controls and cell samples from cell lines were collected and reverse transcription (RT)‐PCR was used to monitor the presence of RhoBTB2 mRNA. The protein expression of RhoBTB2 was detected by immunohistochemical staining. Cumulative survival time was assessed by the Kaplan–Meier method and Cox regression model. We discovered that RhoBTB2 expression was lacking in a breast ductal epithelial carcinoma cell line T‐47D but was expressed in other types of tumor cell lines and normal tissues we tested. The results from tissue samples showed that RhoBTB2 was absent in 60% of breast cancers on both the mRNA and protein level. The results from RT‐PCR were completely uniform with those from immunohistochemistry. We demonstrated that loss of RhoBTB2 more frequently occurred in postmenopausal patients of age ≥50 yr old and in patients with infiltrating ductal carcinoma of the breast. The prognostic value of RhoBTB2 in breast cancers also be assessed by a long‐term follow‐up investigation and we found that patients with RhoBTB2‐negative breast cancer were linked to poor clinical prognosis. Therefore, the loss of RhoBTB2 expression is a common occurrence in breast cancers and it is an important factor in the development and prognosis of sporadic breast cancer. © 2009 Wiley‐Liss, Inc.
Homocysteine‐lowering therapy or antioxidant therapy for bone loss in Parkinson's disease
Authors: Lee Seung Hun , Kim Mi Jung , Kim Beom‐Jun , Kim Sung Reul , Chun Sail , Ryu Jin Sook , Kim Ghi Su , Lee Myoung Chong , Koh Jung‐Min , Chung Sun Ju 
Published: November 2009

AbstractWe investigated whether homocysteine (Hcy)‐ lowering therapy or an antioxidant prevented bone loss in Parkinson's disease (PD) patients taking levodopa. Forty‐two PD patients with low bone mineral density (BMD) taking levodopa were randomly assigned to Hcy‐lowering therapy (5 mg folate and 1500 μg vitamin B12 daily), α‐lipoic acid (α‐LA) therapy (1200 mg daily), or control groups. Primary outcomes were BMD changes from baseline to 12 months. Secondary outcomes were changes in Hcy level, and C‐telopeptide (CTX) levels at 12 months. Forty‐one patients completed the study. Hcy‐lowering therapy resulted in significantly greater BMD changes at the lumbar spine (4.4%), total femur (2.8%), and femur shaft (2.8%) than control (P = 0.005–0.023). BMD changes in the α–LA therapy group were similar to those of the control group, but changes at the trochanter (4.6%) were significantly greater in the α–LA therapy group than in the control group after adjustment for body mass index changes. Hcy concentrations decreased to 35.2% ± 13.4% in the Hcy‐lowering therapy group, but increased in other groups. Serum CTX levels at 12 months tended to be lower in the Hcy‐lowering group (0.442 ± 0.024 ng/mL) than control group (0.628 ± 0.039 ng/mL) (P = 0.159). This small trial suggests that Hcy‐lowering therapy may prevent bone loss in PD patients taking levodopa. © 2009 Movement Disorder Society
Obstacle avoidance to elicit freezing of gait during treadmill walking
Authors: Snijders Anke H. , Weerdesteyn Vivian , Hagen Yolien J. , Duysens Jacques , Giladi Nir , Bloem Bastiaan R. 
Published: November 2009

AbstractFreezing of gait (FOG) is a common and disabling feature of Parkinson's disease (PD). Detailed pathophysiological studies are hampered by the fact that FOG episodes are difficult to elicit in a gait laboratory. We evaluated whether the need to avoid sudden obstacles on a treadmill can provoke FOG. We included 21 PD patients (15 with self‐reported off‐period FOG). Patients were tested in the off‐state. FOG during overground walking was assessed using a standardized gait trajectory and axial 360° turns. Subsequently, patients walked on a motorized treadmill with suddenly appearing obstacles that necessitated compensatory stepping. Performance was videotaped, and presence of FOG was scored visually by two independent raters. Thirteen patients showed FOG during overground walking. During treadmill walking, obstacle avoidance was associated with 13 unequivocal FOG episodes in eight patients, whereas only one patient froze during undisturbed treadmill walking (Wilcoxon z = −2.0, P = 0.046). FOG episodes elicited by obstacle avoidance were brief (typically <1 s). Almost all episodes were provoked when subjects had a longer available response time. In conclusion, suddenly appearing obstacles on a treadmill can elicit FOG in a controlled laboratory setting. However, the moving treadmill and the obstacle both act as cues, which apparently help to immediately overcome the provoked FOG episode. This may limit the ecological validity of this new approach. © 2009 Movement Disorder Society
β‐Sitosterol exhibits anti‐inflammatory activity in human aortic endothelial cells
Authors: Loizou Stella , Lekakis Ioannis , Chrousos George P. , Moutsatsou Paraskevi 
Published: November 2009

Abstractβ‐Sitosterol, normally present in vegetable‐containing diets, comprises an important component of cholesterol controlling functional foods. It has been associated with cardiovascular protection, exerting its effect mainly through increasing the antioxidant defense system and effectively lowering the serum cholesterol levels in humans. However, its anti‐inflammatory effect on endothelium is unknown. Attachment of leukocytes to the vascular endothelium and the subsequent migration of cells into the vessel wall are early events in atherogenesis, this process requiring the expression of endothelial adhesion molecules. We examined the effect of β‐sitosterol (0.1–200 μM) on (i) the expression of vascular adhesion molecule 1 and intracellular adhesion molecule 1 by cell ELISA and (ii) the attachment of monocytes (U937 cells) in tumor necrosis factor‐α (TNF‐α)‐stimulated human aortic endothelial cells (HAECs) by adhesion assay. The effect on nuclear factor‐kB phosphorylation was also examinedviaa cell‐based ELISA kit. Results showed that β‐sitosterol inhibits significantly vascular adhesion molecule 1 and intracellular adhesion molecule 1 expression in TNF‐α‐stimulated HAEC as well as the binding of U937 cells to TNF‐α‐stimulated HAEC and attenuates the phosphorylation of nuclear factor‐kB p65. This study extends existing data regarding the cardioprotective effect of β‐sitosterol and provides new insights into understanding the molecular mechanism underlying the beneficial effect of β‐sitosterol on endothelial function.
Measurement of caffeic and ferulic acid equivalents in plasma after coffee consumption: Small intestine and colon are key sites for coffee metabolism
Authors: Renouf Mathieu , Guy Philippe A. , Marmet Cynthia , Fraering Anne‐Lise , Longet Karin , Moulin Julie , Enslen Marc , Barron Denis , Dionisi Fabiola , Cavin Christophe , Williamson Gary , Steiling Heike 
Published: November 2009

AbstractPrevious studies on coffee examined absorption of phenolic acids (PA) in the small intestine, but not the contribution of the colon to absorption. Nine healthy volunteers ingested instant soluble coffee (∼335 mg total chlorogenic acids (CGAs)) in water. Blood samples were taken over 12 h, and at 24 h to assess return to baseline. Many previous studies, which used glucuronidase and sulfatase, measured only PA and did not rigorously assess CGAs. To improve this, plasma samples were analyzed after full hydrolysis by chlorogenate esterase, glucuronidase and sulfatase to release aglycone equivalents of PA followed by liquid–liquid extraction and ESI‐LC‐ESI‐MS/MS detection. Ferulic, caffeic and isoferulic acid equivalents appeared rapidly in plasma, peaking at 1–2 h. Dihydrocaffeic and dihydroferulic acids appeared in plasma 6–8 h after ingestion (Tmax=8–12 h). Substantial variability in maximum plasma concentration and Tmax was also observed between individuals. This study confirms that the small intestine is a significant site for absorption of PA, but shows for the first time that the colon/microflora play the major role in absorption and metabolism of CGAs and PA from coffee.
Cucurbitacin B induces G2 arrest and apoptosis via a reactive oxygen species‐dependent mechanism in human colon adenocarcinoma SW480 cells
Authors: Yasuda Shusuke , Yogosawa Shingo , Izutani Yasuyuki , Nakamura Yoshitaka , Watanabe Hirotsuna , Sakai Toshiyuki 
Published: November 2009

AbstractCucurbitacin B (cucB) is a triterpenoid constituent of Cucurbitaceae vegetables and a promising phytochemical for cancer prevention. However, the mechanism of anti‐tumor activity of cucB remains unknown, especially in colon cancers. Here, we demonstrate for the first time that cucB inhibited growth of human colon cancer SW480 cells through a reactive oxygen species (ROS)‐dependent mechanism. CucB induced G2 phase arrest and apoptosis in a dose‐dependent manner. At the molecular level, cucB reduced the expression of cyclin B1 and cdc25C proteins and activated caspases in SW480 cells. On the other hand, the state of phosphorylation of signaling transducer and activator of transcription 3 (STAT3) was unchanged. We found that cucB increased intracellular ROS levels, and N‐acetylcysteine, a well‐known antioxidant, reduced the changes in expression of the molecules, and suppressed both G2 arrest and apoptosis. These results suggested that cucB induced G2 arrest and apoptosis through a STAT3‐independent but ROS‐dependent mechanism in SW480 cells.
Theoretical and experimental 1H, 13C and 15N NMR studies of N‐alkylation of substituted tetrazolo[1,5‐a]pyridines
Authors: Berionni Guillaume , Pégot Bruce , Goumont Régis 
Published: November 2009

AbstractThe 15N as well as 1H and 13C chemical shifts of nine substituted tetrazolopyridines and their corresponding tetrazolopyridinium salts have been determined by using NMR spectroscopy at the natural abundance level of all nuclei in CD3CN. In this paper, we report, for the first time, the N‐alkylation reaction of electron deficient tetrazolopyridines. The treatment of tetrazolopyridines 5–13 with one equivalent of trialkyloxonium tetrafluoroborate leads to a mixture of two isomers, i.e. N3‐ and N2‐alkyl tetrazolo[1,5‐a]pyridinium salts. It has been observed that the N3‐isomer is always the major isomer, except in the case of the CF3 substituent, where the two isomers are obtained in the same amount. The quaternary tetrazolopyridinium nitrogen N3 is shielded by around 100 ppm (parts per million) with respect to the parent tetrazolopyridine. Experimental data are interpreted by means of density functional theory (DFT) calculations, including solvent‐induced effects, within the conductor‐like polarizable continuum model (CPCM). Good agreements between theoretical and experimental 1H, 13C and 15N NMR were found. The combination of multinuclear magnetic resonance spectroscopy with gauge including atomic orbital (GIAO) DFT calculations is a powerful tool in the structural elucidation for both neutral and cationic heterocycles and in the determination of the orientation of N‐alkylation of tetrazolopyridines. Copyright © 2009 John Wiley & Sons, Ltd.
Finite deformation formulation for embedded frictional crack with the extended finite element method
Authors: Liu Fushen , Borja Ronaldo I. 
Published: November 2009

AbstractWe reformulate an extended finite element (FE) framework for embedded frictional cracks in elastoplastic solids to accommodate finite deformation, including finite stretching and rotation. For the FE representation, we consider a Galerkin approximation in which both the trial and weighting functions adapt to the current contact configuration. Contact and frictional constraints employ two Kuhn–Tucker conditions, a contact/separation constraint nesting over a stick/slip constraint for the case when the crack faces are in frictional sliding mode. We integrate finite deformation bulk plasticity into the formulation using the multiplicative decomposition technique of nonlinear continuum mechanics. We then present plane strain simulations demonstrating various aspects of the extended FE solutions. The mechanisms considered include combined opening and frictional sliding in initially straight, curved, and S‐shaped cracks, with and without bulk plasticity. To gain further insight into the extended FE solutions, we perform mesh convergence studies focusing on both the global and the local responses of structures with cracks, including the distribution of the normal component of traction on the crack faces. Copyright © 2009 John Wiley & Sons, Ltd.
Factors associated with medicine use among children aged under 12 years—a population survey in Finland
Authors: Hämeen‐Anttila Katri , Lindell‐Osuagwu Leena , Sepponen Kati , Vainio Kirsti , Halonen Pirjo , Ahonen Riitta 
Published: November 2009

AbstractPurposeThe goal was to determine the prevalence of medicine use and to provide population‐based information on factors associated with medicine use, including prescribed and over‐the‐counter (OTC) medicines, in children aged under 12 years.MethodsA cross‐sectional population survey of a random sample of children aged under 12 years (n = 6000) was carried out in Finland in spring 2007, with a response rate of 67%. A questionnaire was sent to their parents. Current use of medicines prescribed by a physician and use of OTC medicines during the preceding two days were the main outcome measures.ResultsThe prevalence of current prescribed medicine use was 17%, and the 2‐day prevalence of OTC medicine use 17% (vitamins excluded). The use of prescribed medicines was higher among children with illnesses diagnosed by a physician. Additionally, predictors for the use of prescribed medicines were young age among boys, health status worse than good, and the use of any prescribed medicines by a parent. The predictors for the use of OTC medicines by the child were young age and fairly good to poor health status, and the use of OTC medicines by a parent. However, children with any illnesses diagnosed by a physician were less likely to use OTC medicines.ConclusionsA considerable proportion of children use prescription and OTC medicines in Finland. Young age and health‐related factors, morbidity and health status, and parental medicine use predicted children's medicine use. Further studies are needed to examine the association between parents' and children's medicine use. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of electron beam irradiation on the crystallization of silk fibroin fiber‐reinforced poly(ε‐caprolactone) biocomposites
Authors: Qiao Xiuying , Li Wei , Sun Kang , Chen Xiaodong 
Published: November 2009

AbstractIn the medical industry, ionizing radiation has attracted increasing interest in recent years for the sterilization of biomedical materials due to its high effectiveness at relatively low cost and simple operation. In the study reported here, silk fibroin (SF) fiber was used to prepare novel reinforced poly(ε‐caprolactone) (PCL) biocomposites, and the effect of electron beam irradiation on both non‐isothermal and isothermal crystallization kinetics of the SF/PCL biocomposites was investigated. The models of Ozawa treatment, Avrami analysis and regime theory of crystal growth are applicable for describing the non‐isothermal and isothermal crystallization kinetics of the irradiated PCL and SF/PCL composites. Compared with non‐irradiated PCL and SF/PCL composites, the irradiated specimens exhibit the same crystallization regime (regime II) and similar lateral surface free energy (σ), except for smaller fold surface free energy (σe) and work of chain folding (q). The crosslinked PCL network formed in the irradiation process can act as a nucleation agent and accelerate the primary crystallization of PCL. However, the restriction effect of the crosslinked PCL network on the molecular chain mobility will reduce the overall crystallization rate of PCL, and this restriction effect appears stronger in the non‐isothermal crystallization process than in the isothermal crystallization process. Copyright © 2009 Society of Chemical Industry
Ethylene–propylene copolymer/ordered polysilsesquioxane nanocomposites prepared via organic acid‐ or base‐catalyzed binary silica water‐crosslinking reactions
Authors: Adachi Kenta , Hirano Tomoyuki , Kasai Paul H , Nakamae Katsuhiko , Iwabuki Hitoshi , Murakami Koji 
Published: November 2009

AbstractIn situ silica sol–gel‐derived organic–inorganic hybrid materials, which comprise a vinyltrimethoxysilane‐grafted ethylene–propylene copolymer (EPR‐g‐VTMS) and n‐hexyltrimethoxysilane (HTMS), were successfully prepared in the presence of an organic acid and base catalyst. Benzenesulfonic acid and aniline were selected as the organic acid and base catalyst, respectively, to examine the progress and effect of progressive changes in the silane water‐crosslinking reaction of EPR‐g‐VTMS/HTMS composites. The water‐crosslinked EPR‐g‐VTMS/HTMS composites were characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy, gel content, solid‐state 29Si cross‐polarization/magic‐angle spinning NMR, wide‐angle X‐ray scattering, tensile strength and field‐emission scanning electron microscopy measurements. These results revealed that the type of catalyst has a substantial influence on the nature of siloxane bonds and eventually the physical tensile properties of the water‐crosslinked EPR‐g‐VTMS/HTMS composites, which can be explained mainly from knowledge of the traditional acid‐ and base‐catalyzed silica sol–gel reaction. Moreover, an in‐depth analysis of the aniline‐catalyzed composites indicated the formation of ladder‐type poly(n‐hexylsilsesquioxane)s and the presence of a highly ordered structure with a thickness equal to the length of two n‐hexyl groups in all‐trans conformation. We demonstrate potential for the future design of highly ordered silicate‐based organic–inorganic hybrid nanocomposites. Copyright © 2009 Society of Chemical Industry
Origin of significant solvent effects on 1J(CC) spin–spin coupling in some acetylenes: hydrogen bonding and solvent polarity
Authors: Biedrzycka Zenobia , Kamieńska‐Trela Krystyna , Witanowski Michał 
Published: November 2009

AbstractIt is demonstrated that some acetylenes, those of the RCCH structure, display anomalously high sensitivity to solvent effects of their 1J(CC) coupling while RCCR acetylenes fail to show that. The solvent‐induced variation in the latter coupling does not exceed 3 Hz; this seems to be the upper limit of variation of any J(CC) and J(CH) coupling in the molecular system studied which included: acetylene (in 13 solvents), phenylacetylene (in 12 solvents), 1‐phenylpropyne, and 2‐hexyne (two solvents each), and the only exceptions are 1J(CC) in acetylene, which is shown to vary within about 13 Hz, and that in phenylacetylene where the range amounts to about 8 Hz. These apparent anomalies are explained in the present study in terms of two effects of prime importance, solvent polarity and the solute‐to‐solvent hydrogen bonds where the CH moiety in RCCH acetylenes acts as a donor of hydrogen bonds to acceptor sites in the solvent concerned. Copyright © 2009 John Wiley & Sons, Ltd.