bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bulk polytransesterification of L‐lactic acid esters: An alternative route to synthesize poly(lactic acid)
Authors: Marques Dina S. , Gil M. H. , Baptista Cristina M. S. G. 
Published: April 2012

AbstractThe synthesis of poly(lactic acid) (PLA) by bulk polytransesterification of different L‐lactic acid esters was successfully carried out. The experiments were performed in two steps: a first one at 170°C, maximum temperature, and atmospheric pressure, to obtain a viscous oligomer; and a final step at 180°C and under reduced pressure to improve the byproduct elimination and increase the polymerization degree. The ethyl L‐lactate polytransesterification in the presence of the binary catalytic system Sb2O/Zn(O2CCH3)2·2H2O allowed achieving the highest average molecular weight, 22,300 g mol−1. The yellowing of the melt polymer samples was recorded. The resulting materials were subjected to several characterization techniques: the chemical structure of PLA was confirmed by 1H‐NMR, the molecular weight was determined by size exclusion chromatography, thermal behavior measured by differential scanning calorimetry and racemization extent by specific rotation measurements. A special attention was paid to the polymer optical purity, as it is of major importance to assess its quality and the significance of the synthesis route. To the best of our knowledge, there is no previous report dealing with the synthesis of PLA by bulk polytransesterification. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Isobaric relaxation phenomenon of mixed PMMA/PS‐b‐PEO monolayers at different temperatures
Authors: Jheng Kai‐Teng , Hsu Wen‐Ping 
Published: April 2012

AbstractThe objective of this research was to find out the effect of molecular weight of poly(methyl methacrylate) (PMMA) and temperature on the isobaric relaxation behaviors of mixed PMMA/poly(styrene)‐block‐poly(ethylene oxide) (PS‐b‐PEO) monolayers. Isobaric relaxation experiments of mixed monolayers of PMMA with different molecular weights and PS‐b‐PEO at the air/water interface were investigated at three different temperatures (10, 25, and 40°C). The PS‐b‐PEO monolayer was found to exhibit a fast relaxation curve (i.e., the surface area decreased significantly with increasing time). Addition of PMMA into PS‐b‐PEO slowed the relaxation behavior especially at the lowest experimental temperature (10°C). It was shown that the area relaxation process of mixed PMMA/PS‐b‐PEO monolayers could be well represented by a model considering the nucleation and growth mechanisms. The characteristic exponent x values were found to be almost temperature independent. The kx values were detected to decrease mostly as a result of temperature elevation regardless of pure or mixed monolayers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Multifunctional ZnO‐biopolymer nanocomposite coatings for health‐care polymer foams and fabrics
Authors: Sanoop P. K. , Mahesh K. V. , Nampoothiri K. M. , Mangalaraja R. V. , Ananthakumar S. 
Published: April 2012

AbstractBiopolymer‐mediated sonochemical synthesis has been carried out for obtaining stable, nanocrystalline ZnO‐biopolymer nanocomposite colloids to be applied on polymer foam and cotton fabrics to ultimately produce multifunctional, heath‐care surface modifications.In situnucleation and growth of nano‐ZnO was achieved by ultrasonication at ∼ 60°C in aqueous biopolymer media prepared using starch, gelatin, chitosan, and agar. Phase analysis, structure–bonding characteristics, ZnO morphology, particle size distributions, rheology, and thermal decompositions were studied using XRD, FTIR, SEM/TEM, viscometer, and TG/DTA tools. Morphologically varied nanocrystalline ZnO of size ∼ 40 nm were synthesized. Biopolymers media resulted in stable ZnO colloids through steric stabilization. ZnO‐biopolymer nanocomposites colloid was applied on polyurethane foams and cotton fabric substrates by dip coating. These coatings were examined for the UV photoactivity and resistance to fungi growth. A comparison has been made among the biopolymers. It is shown that the surface coatings of ZnO‐biopolymer nanocomposites can produce anti‐fungal, UV active polymer foams and fabrics. The study has significant relevance in automobile and hospital industries because such functionally modified polymer foams and cotton fabrics can be disinfected and refreshed just by periodic application of water‐free, UV cleaning. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Carbon nanotube/polypropylene composite particles for microwave welding
Authors: Wu Tongfei , Pan Yongzheng , Liu Erjia , Li Lin 
Published: April 2012

AbstractMultiwalled carbon nanotube (MWCNT)/polypropylene (PP) composite particles with various compositions were prepared by mechanical grinding of PP microparticles and MWCNT powders in a mortar at room temperature. Scanning electron microscopy (SEM) revealed that PP particles were coated by MWCNTs, forming a core‐shell structure. The electrical resistivity versus temperature behavior of MWCNT/PP composite particles and the changes in phase structures before and after melting were studied. Furthermore, MWCNT/PP composite particles with 4 wt % MWCNT were used to weld PP substrates under microwave irradiation. The effects of the irradiation duration and the compression pressure on the welding strength were examined. Here, we have demonstrated a simple and economic method for polymer welding. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigation of the molecular weight of polyethylene using rheological techniques
Authors: Li Pengpeng , Yang Shiyuan , Wang Meiling 
Published: April 2012

AbstractThe zero shear viscosity (η0), relaxation time, relaxation spectrum index (RSI) of 20 metallocene‐catalyzed, and conventional polyethylenes are presented. The effect of molecular weight (Mw) determined by gel‐permeation chromatography on rheology parameters was analyzed. The dependence of zero shear viscosity or relaxation time on molecular weight allowed the polyethylene samples to be separated into three different groups and different values of parameter in
${\eta _{\rm{0}}} = K{{\rm{(}}{M_w})^\alpha }$
were obtained, respectively. Two groups of polymers display viscosity deviation from linear relationship and the reason was attributed to different level of long‐chain branching and high‐molecular weight tails. The intrinsic reason was disclosed when relaxation spectra at frequencies between 1 s and 10 s were involved and RSI was used for quantitative analysis. Thus, an alternative single rheological method, based on the effect of molecular structure on dynamic rheological behaviors, was proposed to evaluate the molecular weight of polyethylene. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
pH‐responsive release behavior of genipin‐crosslinked chitosan/poly(ethylene glycol) hydrogels
Authors: Liu Yangshuo , Chen Wenbao , Kim Hyung‐Il 
Published: April 2012

AbstractChitosan/poly(ethylene glycol) blends were crosslinked by the nontoxic genipin as a crosslinker to produce the pH‐responsive hydrogels. The pH‐responsive swelling and releasing behavior of chitosan/poly(ethylene glycol) hydrogels was studied by varying the contents of poly(ethylene glycol) (PEG) and genipin, and the molecular weights of PEG. The drug release increased as the pH of the medium decreased, because the protonation of amino acids in chitosan chains at the acidic condition caused the higher swelling of hydrogels. The drug release increased as the content of PEG increased, because the larger pores were formed in the hydrogel and the higher swelling of matrix was obtained. The drug release decreased with the increase of the content of genipin, because the higher degree of crosslinking impeded the diffusion of drug from the hydrogel matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synovial fluid from patients with early osteoarthritis modulates fibroblast‐like synoviocyte responses to Toll‐like receptor 4 and Toll‐like receptor 2 ligands via soluble CD14
Authors: Nair Anjali , Kanda Veero , Bush‐Joseph Charles , Verma Nikhil , Chubinskaya Susan , Mikecz Katalin , Glant Tibor T. , Malfait Anne‐Marie , Crow Mary K. , Spear Greg T. , Finnegan Alison , Scanzello Carla R. 
Published: April 2012

AbstractObjectiveSynovial inflammation, a feature of both osteoarthritis (OA) and meniscal injury, is hypothesized to be triggered in part via stimulation of Toll‐like receptors (TLRs). We undertook this study to test whether a TLR‐2– or TLR‐4–stimulating factor in synovial fluid (SF) from patients with early knee OA with meniscal injury could lead to inflammatory activation of synoviocytes.MethodsSF was obtained from patients with early OA cartilage damage undergoing arthroscopic meniscal procedures. SF was used to stimulate primary cultures of fibroblast‐like synoviocytes (FLS) and cell lines transfected with TLR‐2 or TLR‐4. SF was used either alone or in combination with a TLR‐2 stimulus (palmitoyl‐3‐cysteine‐serine‐lysine‐4 [Pam3CSK4]) or a TLR‐4 stimulus (lipopolysaccharide [LPS]). In blocking experiments, SF was preincubated with anti‐CD14 antibody.ResultsSF from these patients did not stimulate interleukin‐8 (IL‐8) release from TLR transfectants. Compared with SF on its own, SF (at concentrations of 0.09–25%) in combination with TLR‐2 or TLR‐4 ligands resulted in significant augmentation of IL‐8 release from both transfectants and primary FLS. Soluble CD14 (sCD14), a coreceptor for TLRs, was measured in SF from patients with early OA at levels comparable to those in patients with advanced OA and patients with rheumatoid arthritis. Blockade with anti‐CD14 antibody abolished the ability of SF to augment IL‐8 production in response to LPS, and diminished Pam3CSK4 responses.ConclusionSF augments FLS responses to TLR‐2 and TLR‐4 ligands. This effect was largely due to sCD14. Our results demonstrate that sCD14 in the setting of OA and meniscal injury sensitizes FLS to respond to inflammatory stimuli such as TLR ligands.
Chinese consumer ethnocentrism: A field experiment
Authors: Bi Xiaogang , Gunessee Sailesh , Hoffmann Robert , Hui Wendy , Larner Jeremy , Ma Qing‐Ping , Thompson Frauke Mattison 
Published: April 2012

ABSTRACTConsumer ethnocentrism presents barriers for internationalising organisations. In China, evidence of a resurgent nationalism partly fuelled by rapid economic growth portends a shift in consumption away from foreign towards domestic products. On the other hand, rising consumer demand for branded and luxury products cannot be fully met domestically. However, much of the available evidence on Chinese consumer ethnocentrism is anecdotal and is based on attitudinal surveys that, as accurate measures of actual purchasing behaviour, suffer from certain methodological issues. In response, we report an experiment that measures the ethnocentrism of 447 Chinese consumers as their incentive‐compatible choices between foreign and domestic products in a field setting. Our findings show little effect of foreign origin on subjects' choices that were only weakly related with attitudinal measures including the commonly used consumer ethnocentric tendencies scale (CETSCALE). Our results question the existence of ethnocentric consumer behaviour in China and the use of CETSCALE to gauge it generally. Copyright © 2012 John Wiley & Sons, Ltd.
ent‐Kaurane Diterpenoids from Isodon eriocalyx var. laxiflora
Authors: Wang Weiguang , Wu Haiyan , Du Xue , Yan Juming , Li Yan , Pu Jianxin , Sun Handong 
Published: April 2012

AbstractFour new ent‐kaurane diterpenoids, 6β,13α,15β‐trihydroxy‐16‐ene‐3α,20‐epoxy‐ent‐kaur‐1,7‐dione (1), 6‐hydroxy‐3α,20‐epoxy‐5(6)‐ene‐ent‐kaur‐1,7,15‐trione (2), 6‐hydroxy‐15β‐acetoxy‐3α,20‐epoxy‐16β,17‐epoxy‐5(6)‐ene‐ent‐kaur‐1,7‐dione (3), 3α,17‐dihydroxy‐15(16)‐ene‐ent‐kaur‐7‐one (4), along with four known compounds 5–8 were isolated from the leaves of Isodon eriocalyx var. laxiflora. The structures were elucidated by extensive spectroscopic methods (IR, UV, MS and NMR). The cytotoxic activities of these compounds were evaluated by MTT assay. Compound 8 showed moderate inhibitory effects on HL‐60, SMMC‐7721, MCF‐7 and SW‐480 cell lines.
Rapid Determination of Costunolide and Dehydrocostuslactone in Human Plasma Sample and Chinese Patent Medicine Xiang Sha Yang Wei Capsule Using HPLC‐DAD Coupled with Second‐order Calibration
Authors: Liu Yajuan , Wu Hailong , Zhu Shaohua , Kang Chao , Xu Hui , Su Zhiyi , Gu Huiwen , Yu Ruqin 
Published: April 2012

AbstractA novel methodology that combines high performance liquid chromatography with photodiode‐array detector (HPLC‐DAD) coupled with second‐order calibration method based on alternating trilinear decomposition (ATLD) algorithm was used in determination of the effective constituents such as costunolide and dehydrocostuslactone, in plasma sample and Chinese patent medicine Xiang Sha Yang Wei (XSYW) capsule. Complicated systems such as plasma and Chinese patent medicine which have intricate components are tedious to isolate and purify. The problem that chromatographic peaks are heavily overlapped among the analytes and interferents from the background matrices can be resolved, and the satisfactory quantification results have been gained with the help of the ATLD algorithm which utilized "mathematical separation" instead of partial "physical or chemical separation". Meanwhile, HPLC‐MS/MS method was used to validate the accuracy of the proposed determination method.
Dental x‐rays and risk of meningioma
Authors: Claus Elizabeth B. , Calvocoressi Lisa , Bondy Melissa L. , Schildkraut Joellen M. , Wiemels Joseph L. , Wrensch Margaret 
Published: April 2012

AbstractBACKGROUND:Ionizing radiation is a consistently identified and potentially modifiable risk factor for meningioma, which is the most frequently reported primary brain tumor in the United States. The objective of this study was to examine the association between dental x‐rays—the most common artificial source of ionizing radiation—and the risk of intracranial meningioma.METHODS:This population‐based case‐control study included 1433 patients who had intracranial meningioma diagnosed at ages 20 to 79 years and were residents of the states of Connecticut, Massachusetts, North Carolina, the San Francisco Bay Area, and 8 counties in Houston, Texas between May 1, 2006 and April 28, 2011 (cases). A control group of 1350 individuals was frequency matched on age, sex, and geography (controls). The main outcome measure for the study was the association between a diagnosis of intracranial meningioma and self‐reported bitewing, full‐mouth, and panorex dental x‐rays.RESULTS:Over a lifetime, cases were more than twice as likely as controls (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.4‐2.9) to report having ever had a bitewing examination. Regardless of the age at which the films were obtained, individuals who reported receiving bitewing films on a yearly basis or with greater frequency had an elevated risk for ages <10 years (OR, 1.4; 95% CI, 1.0‐1.8), ages 10 to 19 years (OR, 1.6; 95% CI, 1.2‐2.0), ages 20 to 49 years (OR, 1.9; 95% CI, 1.4‐2.6), and ages ≥40 years (OR, 1.5; 95% CI, 1.1‐2.0). An increased risk of meningioma also was associated with panorex films taken at a young age or on a yearly basis or with greater frequency, and individuals who reported receiving such films at ages <10 years had a 4.9 times increased risk (95% CI, 1.8‐13.2) of meningioma. No association was appreciated for tumor location above or below the tentorium.CONCLUSIONS:Exposure to some dental x‐rays performed in the past, when radiation exposure was greater than in the current era, appears to be associated with an increased risk of intracranial meningioma. As with all sources of artificial ionizing radiation, considered use of this modifiable risk factor may be of benefit to patients. Cancer 2012. © 2012 American Cancer Society.
Reversal of endothelial progenitor cell dysfunction in patients with type 2 diabetes using a conditioned medium of human embryonic stem cell‐derived endothelial cells
Authors: Ho Jenny C. Y. , Lai Wing‐Hon , Li Ming‐Fang , Au Ka‐Wing , Yip Mei‐Chu , Wong Navy L. Y. , Ng Ethel S. K. , Lam Francis F. Y. , Siu Chung‐Wah , Tse Hung‐Fat 
Published: April 2012

AbstractBackgroundThe potential clinical application of bone marrow or peripheral blood‐derived progenitor cells for cardiovascular regeneration in patients with diabetes mellitus (DM) is limited by their functional impairment. We sought to determine the mechanisms of impaired therapeutic efficacy of peripheral blood‐derived progenitor cells in type 2 DM patients and evaluated the use of cell‐free conditioned medium obtained from human embryonic stem cell‐derived endothelial‐like cells (ESC‐ECs) to reverse their functional impairment.MethodsThe angiogenic potential of late outgrowth endothelial cells (OECs) and cytokine profile of the conditional medium of proangiogenic cells (PACs) derived from peripheral blood‐mononuclear cells of healthy control and DM patients and ESC‐ECs was compared by in vitro tube formation assay and a multiplex bead‐based immunoassay kit, respectively. The in vivo angiogenic potential of ESC‐ECs derived conditioned medium in rescuing the functional impairment of PB‐PACs in DM patients was investigated using a hindlimb ischemia model.ResultsHuman ESC‐ECs had similar functional and phenotypic characteristics as OECs in healthy controls. Cytokine profiling showed that vascular endothelial growth factor, stromal cell‐derived factor 1 and placental growth factor were down‐regulated in PACs from DM patients. Tube formation assay that revealed functional impairment of OECs from DM patients could be rescued by ESC‐ECs conditioned medium. Administration of ESC‐ECs conditioned medium restored the therapeutic efficacy of PB‐PACs from DM patients in a mouse model of hindlimb ischemia.ConclusionsOur results showed that peripheral blood‐derived progenitor cells from DM patients have impaired function because of defective secretion of angiogenic cytokines, which could be restored by supplementation of ESC‐ECs conditioned medium. Copyright © 2012 John Wiley & Sons, Ltd.
Recognition of heat shock protein 60 epitopes in children with type 1 diabetes
Authors: Verrijn Stuart A. A. , de Jager W. , Klein M. R. , Teklenburg G. , Nuboer R. , Hoorweg J. J. G. , de Vroede M. A. M. J. , de Kruijff I. , Fick M. , Schroor E. J. , van der Vlist G. J. , Meerding J. , Kamphuis S. , Prakken B. J. 
Published: April 2012

AbstractBackgroundTreatment with a specific HSP60 epitope in new onset of type 1 diabetes (T1D) patients has been shown to preserve endogenous insulin production. Previously, recognition of pan HLA‐DR‐binding HSP60 epitopes in various autoimmune diseases was found; this study investigated recognition of these epitopes in newly diagnosed T1D patients and correlated findings to the occurrence of a partial remission.MethodsPeripheral blood mononuclear cells of 18 children with T1D were prospectively collected at disease onset and a few months after diagnosis. Epitope‐specific T‐cell proliferation and cytokine production (intracellular and in culture supernatants) were measured. Results were compared with 31 longstanding T1D patients and ten healthy controls.ResultsAlthough HSP60 epitope‐specific T‐cell proliferative responses were detected, overall proliferative responses were low. At onset, epitope‐specific intracellular IFN‐γ production was higher in T1D patients compared with healthy controls (p < 0.05). At follow‐up, both IL‐10 and IFN‐γ production were higher in those without a partial remission than in those with a partial remission (both p < 0.05). Also, IL‐10 and IFN‐γ production were higher compared with onset for patients without a PR (both p < 0.01). In supernatants of HSP60 epitope‐specific T‐cell cultures, no substantial differences in cytokine production were found between T1D patients with and without a partial remission, either at onset or a few months after onset. As patient numbers were small, results should be interpreted with caution.ConclusionsPan‐DR‐binding HSP60 peptides induced low peptide‐specific proliferative responses and peptide‐specific production of some, mainly intracellular, cytokines in T1D patients. Recognition did not differ significantly between patient groups and various time points. Copyright © 2012 John Wiley & Sons, Ltd.
Vanadium Analogues of Nonfunctionalized and Amino‐Functionalized MOFs with MIL‐101 Topology – Synthesis, Characterization, and Gas Sorption Properties
Authors: Biswas Shyam , Couck Sarah , Grzywa Maciej , Denayer Joeri F. M. , Volkmer Dirk , Van Der Voort Pascal 
Published: April 2012

AbstractSyntheses, characterization, and gas sorption properties of two new vanadium‐based metal–organic frameworks [V3OCl(DMF)2(BDC)3]·3.1DMF·10H2O·0.1BDC (V–MIL‐101 or 1) and [V3OCl(DMF)2(BDC–NH2)3]·2.8DMF·H2O·0.1BDC–NH2 (V–MIL‐101–NH2 or 2) (DMF = N,N′‐dimethylformamide; BDC = terephthalate; BDC–NH2 = 2‐aminoterephthalate) having MIL‐101 topology are presented. Compounds 1 and 2 were prepared under similar solvothermal conditions (150 °C, 24 h) in DMF by using VCl3 and H2BDC or H2BDC–NH2, respectively. Determination of lattice parameters from X‐ray powder diffraction (XRPD) patterns of thermally activated compounds revealed their structural similarity with chromium‐, iron‐, and aluminum‐based solids having two types of mesoporous cages and accessible metal sites. The phase purity of the compounds was ascertained by XRPD analysis, diffuse reflectance Fourier transform (DRIFT) spectroscopy, and elemental analysis. Thermogravimetric analyses (TGA) and temperature‐dependent XRPD (TDXRPD) experiments indicate that the compounds are stable up to 320 and 240 °C, respectively, under an argon atmosphere. Removal of the guest DMF molecules by thermal activation enables the compounds to adsorb significant amounts of N2 (690 and 555 cm3 g–1 at p/p0 = 1 for 1 and 2, respectively) and CO2 (9.0 and 4.3 mmol g–1 at 24.5 and 22.8 bar for 1 and 2, respectively).
Cicindeloine from Stenus cicindeloides – Isolation, Structure Elucidation, and Total Synthesis (Eur. J. Org. Chem. 12/2012)
Authors: Müller Tobias , Göhl Matthias , Lusebrink Inka , Dettner Konrad , Seifert Karlheinz 
Published: April 2012

AbstractThe cover picture shows the rove beetle Stenus cincindeloides on a piece of wood and the retrosynthetic disconnection of the novel piperideine alkaloid cicindeloine. We have isolated this spiro compound from the beetle's pygidial glands and elucidated the structure by NMR spectroscopy. The absolute configuration of the alkaloid was determined by an iterative synthetic approach. With the known stereochemistry in hand, we developed a straightforward enantio‐ and diastereoselective method to access this interesting compound, which could be synthesized on gram‐scale. Details are discussed in the article by K. Seifert et al. on p. 2323 ff. magnified image
DNA hyperploidy as a marker for biological response to bladder carcinogen exposure
Authors: Hemstreet George P. , Schulte Paul A. , Ringen Knut , Stringer William , Altekruse Ernest B. 
Published: April 2012

AbstractA marker for biological response to bladder carcinogen exposure was evaluated in a cross‐sectional study of 504 workers at high risk due to a range of exposures to various carcinogenic aromatic amines, primarily 2‐naphthylamine. A quantitative fluorescence cytology method using the DNA‐binding dye, acridine orange, was employed to measure DNA in exfoliated urothelial cells. DNA hyperploidy (>5 C) was observed in 16 (21.6%) of 74 workers who had been exposed compared with 15 (3.5%) of 430 workers who had not (p < 0.001). The prevalence of DNA hyperploidy increased in a dose‐response manner from 3.5% to 60% with increasing duration of exposure. The association between DNA hyperploidy and exposure persisted when adjustment was made for age and cigarette smoking (p = 0.0001). The prevalence of the marker was greatest for exposed workers who smoked (23%), and lowest for those who had no exposure and who had not smoked (2%). This study indicates that DNA hyperploidy can serve as a marker for identifying workers who are at increased risk in occupational groups exposed to bladder carcinogens.