bluuebunny/crossref_metadata_2025 huggingface dataset:
Institutional Logics in the Study of Organizations: The Social Construction of the Relationship between Corporate Social and Financial Performance
Authors: Orlitzky Marc
Published: July 2012

This study examines whether the empirical evidence on the relationship between corporate social performance (CSP) and corporate financial performance (CFP) differs depending on the publication outlet in which that evidence appears. This moderator meta-analysis, based on a total sample size of 33,878 observations, suggests that published CSP-CFP findings have been shaped by differences in institutional logics in different subdisciplines of organization studies. In economics, finance, and accounting journals, the average correlations were only about half the magnitude of the findings published in Social Issues in Management, Business Ethics, or Business and Society journals (mean corrected correlation coefficientof .22 vs. .49, respectively). Specifically, economists did not find null or negative CSP-CFP correlations, and average findings published in general management outlets (= .41) were closer to Social Issues in Management, Business Ethics, and Business and Society results than to findings reported in economics, finance, and accounting journals.
Strategic Culture and Environmental Dimensions as Determinants of Anomie in Publicly-Traded and Privately-Held Firms
Authors: Johnson Jean L. , Martin Kelly D. , Saini Amit
Published: July 2012

Anomie is a condition in which normative guidelines for governing conduct are absent. Using survey data from a sample of U.S. manufacturing firms, we explore the impact of internal (cultural) and external (environmental) determinants of organizational anomie. We suggest that four internal organizational factors can generate or suppress organizational anomie, including strategic aggressiveness, long-term orientation, competitor orientation, and strategic flexibility. Similarly, we argue that external contextual factors, including competitive intensity and technological turbulence, can influence organizational anomie. We extend anomie and ethics research by considering the impact of these firm cultural and environmental factors according to whether firms are publicly-traded or privately-held. Findings demonstrate that a number of firm cultural and environmental factors can generate or reduce anomie in firms. Moreover, strategic aggressiveness, long-term orientation, and strategic flexibility influence organizational anomie differently depending on whether the firm is publicly-traded or privately-held. Theoretical and practical implications of our findings are discussed.
Influence of Parmigiano Reggiano Diet on Male Sexual Behavior in Rats: Behavioral and Neurochemical Study
Authors: Di Viesti  , G. Carnevale  , M.M. Carrozzo  , M. Zavatti  , M. Baraldi
Published: July 2012

The influence of Parmigiano Reggiano (P.R.) cheese on copulatory behavior was studied in male rats. Sexually naїve, sluggish and potent rats were chronically fed with a diet of P.R. cheese for 10 d. Mount, intromission, ejaculation latencies and the percentage of mounting and ejaculating animals were recorded during the mating test. Microdialysis technique was used to detect the extracellular levels of dopamine (DA) and its metabolite dihydroxyphenylacetic acid (DOPAC) in rat brain following the P.R. diet. The P.R. diet was able to improve sexual behavior in naїve rats increasing the percentage of mounting and ejaculating animals. Moreover it was able to reduce latencies of mounts, intromissions and ejaculations and to increase the percentage of mounting and ejaculating animals in sluggish rats. Finally, in the microdialysis study an increase in DA and its metabolite DOPAC was found in P.R. fed naїve rats in comparison with control group.
Benthaminin 3, a Novel Antibacterial Cassane-Type Furanoditerpenoid from Caesalpinia benthamiana
Authors: Rita A. Dickson  , Kofi Annan  , Theophilus C. Fleischer  , Peter J. Houghton
Published: July 2012

The roots of Caesalpinia benthamiana (synonym. Mezoneuron benthamianum)are considered to be an effective remedy in Ghana for the management of skin diseases and wounds. Bioactivity-guided fractionation of the chloroform extract of the root bark of the plant has resulted in the isolation of a novel cassane-type furanoditerpenoid, designated as benthaminin 3. The structure of the compound was elucidated by the use of spectroscopic techniques. The antibacterial activity of the compound has been assessed using the microdilution assay method. The lowest MIC (63μg/mL) was recorded against Staphylococcus aureus and Bacillus subtilis. The compound wasalso observed to have a mild inhibitory effect against resistant strains of bacteria including methicillin-resistant S. aureus, tetracyline-resistant S. aureus and erythromycin-resistant S. aureus with MIC values greater than 1000μg/mL.
Development of the Caco-2 Model for Assessment of Iron Absorption and Utilisation at Supplemental Levels
Authors: Bianca I. Mergler  , Ewgenia Roth  , Sylvaine F.A. Bruggraber  , Jonathan J. Powell  , Dora I.A. Pereira
Published: July 2012

Caco-2 cells may be typically used as a first step to investigate the bioavailability of different dietary and fortificant forms of iron (Fe) at low levels (< 10 µM) in tissue culture medium (TCM). Whether this model is suitable with supplemental levels of Fe (ca. 200 µM in TCM) is not clear and neither, therefore, is the choice of reference iron compound under those conditions as a ‘positive control’. Here we show that with 200 ?M iron in TCM (serum-free MEM), Fe(II) sulphate precipitates and while high levels of ascorbic acid can prevent this, it is to the detriment of the Caco-2 cell monolayer and/or it adversely affects the pH of the TCM. Adjusting the pH of TCM to account for this issue again leads to Fe precipitation, which is detectable as both a true precipitate (~ 50%) and a nano-precipitate in suspension (~20%). In contrast, Fe(III) maltol which, clinically, appears less toxic to the intestinal mucosa than Fe(II) sulphate, retains solubility at supplemental levels in cell culture medium, without adversely affecting pH or the Caco-2 cell monolayer. Moreover, the iron is also well utilized by the cells as assessed through ferritin formation. Thus Caco-2 cells may also provide a model for screening iron uptake and utilisation at supplemental levels through the cellular generation of ferritin although care must be taken in ensuring (i) appropriate TCM conditions (e.g. pH and chemical speciation of the iron) (ii) monolayer integrity (i.e. the assay response is not an artefact of toxicity) and (iii) that an appropriate reference material is used (e.g. Fe:maltol at 1:5 ratio).
Quantum Therapy: A New Way in Osteoporosis Primary Prevention and Treatment
Authors: Sergio Stagnaro  , Simone Caramel
Published: July 2012

The paper highlights the role played by quantum therapy in Osteoporosis Primary Prevention and treatment. We provide an overview of other useful treatments in Osteoporosis prevention such as CoQ10, Melatonin and Mediterranean Diet comparing their efficacy to that offered by the quantum therapy. This is done through ‘Quantum Biophysical Semeiotics’ bed-side evaluation, monitoring the results and efficiency of ongoing therapies aimed at improving mitochondrial and endothelial function, when it is unpaired in any biological systems.
'Quantum Biophysical Semeiotics’ theory is an extension of medical semeiotics. It is grounded on a multidisciplinary approach that involves chemistry and biology, genetics and neuroscience, chaos theory and quantum physics. It is based on the method of ‘Auscultatory Percussion’, through which by means of the common stethoscope, it is possible to listen to the signs that the body gives us when appropriately stimulated. The stimuli are used to induce consistent behaviour -typical of dissipative systems far from equilibrium, according to Prigogine - in precise and well defined biological systems of the human body, thus giving local qualitative information on the state of health or disease, whether potential, being developed but not yet evident by usual clinical trial, effective or even in chronic phase.
The 'Quantum Biophysical Semeiotics’ theory provides very detailed case studies based on the latency time, duration, and intensity of the reflexes, which play a central role in such a diagnostic method.
Kidney Injury, Insulin Therapy, and Hypoglycemia
Authors: Roland N. Dickerson
Published: July 2012

The intent of this review is to evaluate the literature with respect to increased risk for hypoglycemia for critically ill patients with acute kidney injury or chronic kidney disease who are given insulin therapy. The unique pathophysiology of insulin and glucose metabolism during renal failure that predisposes patients for hypoglycemia is reviewed. Studies that contribute to the understanding and clinical relevance of renal dysfunction upon glycemic control during intensive insulin and continuous nutrition therapy are evaluated. Some practical suggestions for management of hyperglycemia with insulin therapy for critically ill patients with renal failure are given.
Dietary Iron is Associated with Memory in Midlife: Longitudinal Cohort Study
Authors: Anna P. Rickard  , Mark D. Chatfield  , Jonathan J. Powell  , Alison M. Stephen  , Marcus Richards
Published: July 2012

This work examined associations between dietary iron and cognitive function in mid-life adults using data from the 1946 British Birth Cohort, a representative population-based sample of men and women born in England, Scotland or Wales. Linear regression was used to determine the association between dietary iron intake or a measure of available iron (calculated by adjusting iron intake for dietary modifiers that are known to inhibit or enhance iron absorption) at ages 36, 43 and 53 years and cognitive measures at ages 43 and 53 years. Cognitive measures included verbal memory, assessed by a three-trial 15-word learning task, and speed and concentration, assessed by a timed letter search task. Examining the data cross-sectionally; dietary iron at ages 43 and 53 years was positively and significantly associated with verbal memory after adjustment for potential confounders. Examining the data longitudinally; earlier dietary iron exposure was significantly associated with later verbal memory. No associations were observed between dietary iron and measures of speed and concentration when examining the data both cross-sectionally and longitudinally. The current study shows that impaired cognition, specifically memory, resulting from inadequate iron intake may extend beyond childhood and also be present in midlife. This finding, coupled with the high prevalence of people reporting iron intakes below the Lower Reference Nutrition Intake in the UK, provide reason for concern.
Curvilinear vector finite difference approach to the computation of waveguide modes
Authors: Fanti A. , Mazzarella G. , Montisci G.
Published: July 2012

We describe here a Vector Finite Difference approach to the evaluation of waveguide eigenvalues and modes for rectangular, circular and elliptical waveguides. The FD is applied using a 2D cartesian, polar and elliptical grid in the waveguide section. A suitable Taylor expansion of the vector mode function allows to take exactly into account the boundary condition. To prevent the raising of spurious modes, our FD approximation results in a constrained eigenvalue problem, that we solve using a decomposition method. This approach has been evaluated comparing our results to the analytical modes of rectangular and circula rwaveguide, and to known data for the elliptic case.
High‐Affinity Choline Uptake (HACU) and Choline Acetyltransferase (ChAT) Activity in Neuronal Cultures for Mechanistic and Drug Discovery Studies
Authors: Ray Balmiki , Bailey Jason A. , Simon Jay R. , Lahiri Debomoy K.
Published: July 2012

Acetylcholine (ACh) is the neurotransmitter used by cholinergic neurons at the neuromuscular junction, in parasympathetic peripheral nerve terminals, and in important memory‐related circuits in the brain, and takes part in other critical functions. ACh is synthesized from choline and acetyl coenzyme A by the enzyme choline acetyltransferase (ChAT). The formation of ACh in cholinergic nerve terminals requires the transport of choline into cells from the extracellular space and the activity of ChAT. High‐affinity choline uptake (HACU) represents the majority of choline uptake into the nerve terminal and is the acutely regulated, rate‐limiting step in ACh synthesis. HACU can be differentiated from nonspecific choline uptake by inhibition of the choline transporter with hemicholinium. Several methods have been described previously to measure HACU and ChAT activity simultaneously in synaptosomes, but a well‐documented protocol for cultured cells is lacking. We describe a procedure for simultaneous measurement of HACU and ChAT in cultured cells by simple radionuclide‐based techniques. Using this procedure, we have quantitatively determined HACU and ChAT activity in cholinergically differentiated human neuroblastoma (SK‐N‐SH) cells. These simple methods can be used for neurochemical and drug discovery studies relevant to several disorders, including Alzheimer's disease, myasthenia gravis, and cardiovascular disease. Curr. Protoc. Neurosci. 60:7.23.1‐7.23.16. © 2012 by John Wiley & Sons, Inc.
Analysis of Nonsense‐Mediated mRNA Decay in Mammalian Cells
Authors: Nicholson Pamela , Joncourt Raphael , Mühlemann Oliver
Published: June 2012

The nonsense‐mediated mRNA decay (NMD) pathway acts to selectively identify and degrade mRNAs that contain a premature translation termination codon (PTC), and hence reduce the accumulation of potentially toxic truncated proteins. NMD is one of the best studied mRNA quality‐control mechanisms in eukaryotes, and it has become clear during recent years that many physiological mRNAs are also NMD substrates, signifying a role for NMD beyond mRNA quality control as a translation‐dependent post‐transcriptional regulator of gene expression. Despite a great deal of scientific research for over twenty years, the process of NMD is far from being fully understood with regard to its physiological relevance to the cell, the molecular mechanisms that underpin this pathway, all of the factors that are involved, and the exact cellular locations of NMD. This unit details some of the fundamental RNA based approaches taken to examine aspects of NMD, such as creating PTC+ reporter genes, knocking down key NMD factors via RNAi, elucidating the important functions of NMD factors by complementation assays or Tethered Function Assays, and measuring RNA levels by reverse‐transcription quantitative PCR. Curr. Protoc. Cell Biol. 55:27.4.1‐27.4.61. © 2012 by John Wiley & Sons, Inc.
Transition Metal Oxide Work Functions: The Influence of Cation Oxidation State and Oxygen Vacancies
Authors: Greiner Mark T. , Chai Lily , Helander Michael G. , Tang Wing‐Man , Lu Zheng‐Hong
Published: June 2012

Transition metal oxides are capable of a wide range of work functions. This quality allows them to be used in many applications that involve charge transfer with adsorbed molecules, for example as heterogeneous catalysts, as charge‐injection layers in organic electronics, and as electrodes in fuel cells. Chemical and structural factors can alter transition‐metal oxide work functions, often making their work functions difficult to control. Little is known about the effects of the cation oxidation state and point defects on the oxide work function. It is necessary to understand how such chemical and structural factors affect work functions in order to controllably tune transition metal oxides for desired applications. Here, a correlation between the oxide work function and cation oxidation state is demonstrated. This correlation is attributed to the change in cation electronegativity with oxidation state. A model is presented that relates the work function to the oxygen deficiency for d0 oxides in the limit of dilute oxygen vacancies. It is proposed that the rapid initial decrease in work function, observed for d0 oxides, is caused by an increase in the density of donor‐like defect states. It is also shown that oxides tend to have decreased work functions near a metal/metal‐oxide interface as a consequence of the relationship between defects and work function. These insights provide guidelines for tuning transition metal oxide work functions.
Photocatalytic Composites of Silicone Nanofilaments and TiO2 Nanoparticles
Authors: Meseck Georg R. , Kontic Roman , Patzke Greta R. , Seeger Stefan
Published: June 2012

Nanoscale TiO2 photocatalysts are key materials for convenient wastewater treatment and other essential cleaning processes. Immobilization of TiO2 nanoparticles (NPs) is thus indispensable for the facile handling and separation of nanocatalysts as well as for minimizing their potential health and environmental hazards. Silicone nanofilaments are introduced as a new flexible carrier type for titania NPs because they are compatible with a wide range of substrates and they display high chemical stability. TiO2‐NPs are deposited on glass slides covered with thin carpets of silicone nanofilaments in a single reaction step starting from TiF4 and optimized ethanol/water ratios. The resulting composites are characterized using a wide range of electron microscopy and other analytical techniques, and their photocatalytic activity in the decomposition of methylene blue (MB) is superior to immobilized TiO2 references on plain substrates.
Ultrathin Mesoporous NiCo2O4 Nanosheets Supported on Ni Foam as Advanced Electrodes for Supercapacitors
Authors: Yuan Changzhou , Li Jiaoyang , Hou Linrui , Zhang Xiaogang , Shen Laifa , Lou Xiong Wen (David)
Published: June 2012

A facile two‐step method is developed for large‐scale growth of ultrathin mesoporous nickel cobaltite (NiCo2O4) nanosheets on conductive nickel foam with robust adhesion as a high‐performance electrode for electrochemical capacitors. The synthesis involves the co‐electrodeposition of a bimetallic (Ni, Co) hydroxide precursor on a Ni foam support and subsequent thermal transformation to spinel mesoporous NiCo2O4. The as‐prepared ultrathin NiCo2O4 nanosheets with the thickness of a few nanometers possess many interparticle mesopores with a size range from 2 to 5 nm. The nickel foam supported ultrathin mesoporous NiCo2O4 nanosheets promise fast electron and ion transport, large electroactive surface area, and excellent structural stability. As a result, superior pseudocapacitive performance is achieved with an ultrahigh specific capacitance of 1450 F g−1, even at a very high current density of 20 A g−1, and excellent cycling performance at high rates, suggesting its promising application as an efficient electrode for electrochemical capacitors.
Facile Synthesis of Manganese‐Oxide‐Containing Mesoporous Nitrogen‐Doped Carbon for Efficient Oxygen Reduction
Authors: Tan Yueming , Xu Chaofa , Chen Guangxu , Fang Xiaoliang , Zheng Nanfeng , Xie Qingji
Published: June 2012

Developing low‐cost non‐precious metal catalysts for high‐performance oxygen reduction reaction (ORR) is highly desirable. Here a facile, in situ template synthesis of a MnO‐containing mesoporous nitrogen‐doped carbon (m‐N‐C) nanocomposite and its high electrocatalytic activity for a four‐electron ORR in alkaline solution are reported. The synthesis of the MnO‐m‐N‐C nanocomposite involves one‐pot hydrothermal synthesis of Mn3O4@polyaniline core/shell nanoparticles from a mixture containing aniline, Mn(NO3)2, and KMnO4, followed by heat treatment to produce N‐doped ultrathin graphitic carbon coated MnO hybrids and partial acid leaching of MnO. The as‐prepared MnO‐m‐N‐C composite catalyst exhibits high electrocatalytic activity and dominant four‐electron oxygen reduction pathway in 0.1 M KOH aqueous solution due to the synergetic effect between MnO and m‐N‐C. The pristine MnO shows little electrocatalytic activity and m‐N‐C alone exhibits a dominant two‐electron process for ORR. The MnO‐m‐N‐C composite catalyst also exhibits superior stability and methanol tolerance to a commercial Pt/C catalyst, making the composite a promising cathode catalyst for alkaline methanol fuel cell applications. The synergetic effect between MnO and N‐doped carbon described provides a new route to design advanced catalysts for energy conversion.
N‐Heterocyclic Carbene‐Mediated Organocatalytic Transfer of Tin onto Aldehydes: An Easy Access to syn‐Diols and Mechanistic Studies
Authors: Blanc Romain , Nava Paola , Rajzman Michel , Commeiras Laurent , Parrain Jean‐Luc
Published: July 2012

An update of our preliminary communication concerning an efficient organocatalytic procedure for the transfer of tin onto aldehydes is presented. This update combines (i) a full study of the preparation of γ‐silyloxyallylstannanes from β‐substituted enals, (ii) a “one‐pot” sequence (in inter‐ and intramolecular version) including N‐heterocyclic carbene (NHC)‐catalyzed silylstannation reaction/Lewis acid‐promoted allylstannation reaction to furnish the corresponding syn‐diols, and (iii) mechanistic studies on the organocatalytic 1,2‐addition.
Access to Both Enantiomers of α‐Chloro‐β‐keto Esters with a Single Chiral Ligand: Highly Efficient Enantioselective Chlorination of Cyclic β‐Keto Esters Catalyzed by Chiral Copper(II) and Zinc(II) Complexes of a Spiro‐2,2′‐bischroman‐Based Bisoxazoline Ligand
Authors: Li Jie , Pan Wei , Wang Zheng , Zhang Xumu , Ding Kuiling
Published: July 2012

The spiro‐2,2′‐bichroman‐based chiral bisoxazoline ligands (SPANbox) were found to be highly efficient in copper(II)‐ and zinc(II)‐catalyzed asymmetric chlorinations of cyclic β‐keto esters with N‐chlorosuccinimide (NCS) as the chlorination reagent, to give the corresponding α‐chloro‐β‐keto esters in excellent yields in 5–30 min with ee values up to 97%. The copper(II) triflate and zinc(II) triflate complexes of a single SPANbox ligand demonstrated complementary results to each other with respect to the enantioselection, affording both antipodes of the chlorinated product enantiomers with good to excellent optical purities.
Study of the compositional heterogeneity of ethylene/1–hexene copolymers produced over supported catalysts of different composition
Authors: Matsko Mikhail A. , Echevskaya Ludmila G. , Vanina Marina P. , Nikolaeva Marina I. , Mikenas Tatyana B. , Zakharov Vladimir A.
Published: June 2012

Separation into narrow MWD fractions (liquid–liquid fractionation) and preparative TREF (temperature rising elution fractionation) with subsequent analysis of fractions by GPC, FTIR, and 13C NMR spectroscopy were used to study the comonomer distribution of ethylene/1–hexene copolymers produced over highly active supported titanium‐ and vanadium‐magnesium catalysts (TMC and VMC) and a supported zirconocene catalyst. These catalysts produce PE with different MWD: Mw/Mn values vary from 2.9 for zirconocene catalyst, 4.0 for TMC, and 15 for VMC. 1‐Hexene increases polydispersity to 25 for copolymer produced over VMC and hardly affects MWD of the copolymer produced over TMC and zirconocene catalysts. The most broad short chain branching distribution (SCBD) was found for ethylene/1–hexene copolymers produced over TMC. VMC and supported zirconocene catalyst produce copolymers with uniform profile of SCB content vs. molecular weight in spite of great differences in Mw/Mn values (22 and 2.5 respectively). TREF data showed that majority of copolymer produced over supported zirconocene catalyst was eluted at 70–90°C (about 85 wt %). In the case of VMC copolymer's fractions were eluted in the broad temperature interval (40–100°C). Accordingly, TREF data indicate a more homogeneous SCBD in copolymer, produced over supported zirconocene catalyst. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of PES on the morphology and properties of proton conducting blends with sulfonated poly(ether ether ketone)
Authors: Arigonda Mahesh , Deshpande Abhijit P. , Varughese Susy
Published: June 2012

Development of alternate materials to Nafion, based on ionically conducting polymers and their blends is important for the wider applications of proton exchange membrane fuel cells. In this work, blends of sulfonated poly(ether ether ketone) (SPEEK) with poly(ether sulfone) (PES) are investigated. SPEEK with various ion exchange capacity (IEC) was prepared and blended with PES, which is nonionic and hydrophobic in nature. A comparative study of the water uptake, proton conductivity, and thermo‐mechanical characteristics of SPEEK and the blend membranes as a function of the IEC is presented. Addition of PES decreases the water uptake and conductivity of SPEEK. Chemical and thermal stability and mechanical properties of the membrane improve with the addition of PES. The effect of water content on the thermo‐mechanical properties of membranes was also studied. The morphology of blend membranes was studied using SEM to understand the microstructure and miscibility of the components. On the basis of the results, a plausible microstructure of the blends is presented, and is shown to be useful in understanding the variation of different properties with blending. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and characterization of ternary‐copolymer of soluble fluorinated polyimides based on 1,4‐bis (4‐amino‐2‐trifluoromethylphenoxy) benzene
Authors: Fang Cheng , Zhou Yuming , He Man , Bu Xiaohai , Yin Kang , Weng Jiajia , Zhang Zewu
Published: June 2012

A series of novel ternary‐copolymer of fluorinated polyimides (PIs) were prepared from 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene (pBATB), commercially available aromatic dianhydrides, and aromatic diamines via a conventional two‐step thermal or chemical imidization method. The structures of all the obtained PIs were characterized with FTIR, 1H‐NMR, and element analysis. Besides, the solubility, thermal stability, mechanical properties, and moisture uptakes of the PIs were investigated. The weight‐average molecular weight (Mw) and the number‐average molecular weight (Mn) of the PIs were determined using gel‐permeation chromatography (GPC). The PIs were readily dissolved not only in polar solvents such as DMF, DMAc, and NMP, but also in some common organic solvents, such as acetic ester, chloroform, and acetone. The glass transition temperatures of these PIs ranged from 201 to 234°C and the 10% weight loss temperatures ranged from 507 to 541°C in nitrogen. Meanwhile, all the PIs left around 50% residual even at 800°C in nitrogen. The GPC results indicated that the PIs possessed moderate‐to‐high number‐average molecular weight (Mn), ranging from 9609 to 17,628. Moreover, the polymer films exhibited good mechanical properties, with elongations at break of 8–21%, tensile strength of 66.5–89.8 MPa, and Young's modulus of 1.04–1.27 GPa, and low moisture uptakes of 0.54–1.13%. These excellent combination properties ensure that the polymer could be considered as potential candidates for photoelectric and microelectronic applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Extensional viscosity measurements and characterization of poly (vinyl chloride‐co‐vinyl acetate) plastisols and foams
Authors: Zoller Agnes , Marcilla Antonio
Published: July 2012

The foaming of PVC‐VA [Poly (vinyl chloride‐co‐vinyl acetate)] plastisols is a complex combination of processes involving the simultaneous curing of the paste with the evolution of gases caused by the decomposition of the chemical blowing agent. The extensional viscosity is a fundamental characteristic of the material, responsible for the behavior of the system when undergoing the extensional stress produced by the released gases. Nevertheless, such changes have not been considered to the same extent as the complex viscosity evolution or the thermal processes suffered by PVC‐VA plastisols. The objective of the present work is to study the extensional viscosity of the PVC‐VA plastisols prepared with three plasticizers of similar structure, but with different curing and rheological behavior in order to investigate its influence on the quality of the foams obtained. Extensional viscosity measurements under forced prestretch conditions revealed that depending on the structure and consequently on the compatibility of the plasticizer used, each plastisol develops its properties and structure accordingly. DINCH plasticizer (Diisononyl cyclohexane‐1,2‐dicarboxylate presenting alicyclic ring) seems to be the less compatible compared with the other two studied (both presenting aromatic rings) according to its behavior during the curing and foaming processes and may not be able to withstand the pressure evolved by the released gases during the foaming process yielding foams of poorer quality. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and characterization of glucosamine modified poly(ethylene glycol) hydrogels via photopolymerization
Authors: Wang Qunfang , Ren Li , Xu Caixia , Zhai Zhichen , Zhou Jia‐an , Yao Yongchang , Xia Huan , Wang Yingjun
Published: June 2012

This study presented the synthesis and characterization of glucosamine (GlcN) modified poly (ethylene glycol) (PEG) hydrogels. The chemical structure was characterized by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The morphology of hydrogels was observed by scanning electron microscopy (SEM). The results indicated that GlcN was successfully incorporated into PEG hydrogel network. Moreover, the data of the swelling ratio showed that the ratio of GlcN‐modified PEG hydrogels was lower than that of pure poly(ethylene glycol) diacrylated (PEGDA). Biocompatibility of unreacted GlcN monomer and GlcN‐modified hydrogels was also evaluatedin vitro. Compared with glucosamine hydrochloride, 2 and 5 mMN‐acroloyl‐glucosamine monomer exhibited no toxicity against bone marrow stromal cells (BMSCs), while with the concentration increased to 10 mM, cell viability appeared to decrease. However, when BMSCs were encapsulated in GlcN‐modified hydrogels via photopolymerization method, cells remained vigorous viability. Metabolic activity of the encapsulated cells demonstrated GlcN‐modified hydrogels was favorable for cell proliferation. Compared with free GlcN, covalent binding GlcN showed lower cytotoxicity and higher cell proliferation properties. As a result, GlcN‐modified PEGDA hydrogels could be used as safe and injectable cell carriers forin situtissue engineering applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis of sulfated β‐cyclodextrin/cotton/ZnO nano composite for improve the antibacterial activity and dyeability with Azadirachta indica
Authors: Sundrarajan M. , Selvam S. , Ramanujam K.
Published: June 2012

The sulfated β‐cyclodextrin (sb‐cd) was prepared from β‐cyclodextrin and the sb‐cd was crosslinked with cotton fabric using ethylenediaminetetraacetic acid (EDTA) as crosslinker. After crosslinking, the synthesized ZnO nanoparticles were padded on this fabric surface. Then, the treated fabrics were dyed with neem extract. The synthesized polymer, crosslinked and nanoparticle‐treated cotton fabrics were characterized using fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), particle sized analyzer, and transmission electron microscopy (TEM) studies. The antibacterial test was done against Staphylococcus aureus and Escherichia coli bacterium. The composite coated with neem dyed cotton fabric has exhibited 71% of dye uptake with 2–3 fastness grade and it has 99% of antibacterial efficiency for S. aureus and 97% for E. coli bacterium. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Thermal, mechanical, and morphological properties of maleated polypropylene compatibilized Borassus fruit fiber/polypropylene composites
Authors: Sudhakara P. , Kamala Devi A. P. , Venkata Prasad C. , Obi Reddy K. , Dong Woo L. , Kim B. S. , Song J. I.
Published: June 2012

With a view of exploring the potential use of natural recourses, we made an attempt to fabricate new Borassus fruit fiber/polypropylene composites by melt mixing method using 5 wt % of fiber. Fibers were chemically modified by alkali treatment using maleated PP (MAPP) as compatibilizer to improve the adhesion between fibers and matrix. Thermal, mechanical, and morphological properties of untreated, alkali treated, and MAPP modified fiber reinforced composites were explored by thermogravimetric analysis, differential scanning calorimetry, universal testing machine, and scanning electron microscopy (SEM), respectively. Thermal stability of the composites was enhanced to some extent on alkali treatment and addition of MAPP. The tensile strength and modulus, flexural strength and modulus, and impact strength were increased for alkali treated/MAPP composites by 4.5%, 17%, 17.2 %, 9%, and 10% respectively. SEM studies on tensile fractured specimens of unmodified composites reveal the poor fiber‐matrix interaction, whereas the interaction is strong with enhanced mechanical properties for modified fiber composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Photostabilization of polystyrene/montmorillonite nanocomposite. A factorial experimental design 24
Authors: Oliveira Camila F. P. , Cremm Silvio R. , Cruz Gerson H. S. , Fechine Guilhermino J. M.
Published: June 2012

The weathering behavior of polystyrene (PS) and PS/montmorillonite nanocomposite with and without addition of ultraviolet (UV) absorber and/or antioxidant was investigated. Samples were exposed to UV radiation in the laboratory for periods of up to approximately 12 weeks. The samples were exposed for various irradiation intervals, and their tensile and impact strength was monitored through a factorial experimental design 24. The molecular weight, yellowness, and fracture surface were also monitored. The results generated by analysis of variance (ANOVA) Table showed that UV absorber and exposure time had the most important effects positive and negative, respectively. These results could be seen for neat PS and PS/MMT nanocomposite. The presence of antioxidant alone did not have any significant effect but when mixed with UV absorber presented a small synergism. These results corroborate with molecular weight, yellowing and fracture surface of tensile and impact samples. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis, characterization, and film properties of crosslinked chitosan with pentaerythritol tris[3‐(1‐aziridinyl) propionate]
Authors: Soucek Mark D. , Yi Ying
Published: June 2012

The novel crosslinked chitosan derivative (CMCSCL) has been synthesized via carboxymethyl chitosan with pentaerythritol tris[3‐(1‐aziridinyl)propionate] (PEN) as crosslinking reagent. Its structure has been proved by Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis and atomic force micrograph. The mechanical properties and water uptake of CMCSCL films have been measured. The results show that CMCSCL film with 4% PEN crosslinker has a high tensile strength (TS) 17.1 MPa, 13.1% elongation at break, and 99% water uptake. The film with 6% PEN has a TS 15.2 MPa, 10.2% elongation at break, and 111% water uptake. The dosage of the crosslinking agent is the principal factor affecting the mechanical properties and water uptake of these films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Study on the molecular behavior of hydrophobically modified poly(acrylic acid) in aqueous solution and its emulsion‐stabilizing capacity
Authors: Li Quanwei , Yuan Rui , Ying Li
Published: June 2012

In this article, molecular conformation and aggregation behavior of partly hydrophobically modified poly(acrylic acid) (HMPAA) in aqueous solution has been studied by mesoscale simulation approach dissipative particle dynamics for the purpose to find out how the chemical structure and environmental conditions effect its capacity. It has been found that, as a kind of pH‐sensitive polymer, the chemical structure variation of HMPAA carried by adjusting pH and grafting degree influence the taking place of intermolecular and intramolecular associations, which induced the formation of molecular network and help to maintain high bulk phase viscosity of its aqueous solution in larger pH range or under higher salinity comparing with PAA. There exists an optimum grafting degree, above which the increase of the possibility of the intramolecular associations enhance the coiling of the polymer chain and result in destroy of the network. The experimental determination of properties of aqueous solutions of poly(acrylic acid) (U10) and poly alkyl acrylate (U20), such as the bulk phase viscosity and oil/water interface tension, accord well with the molecular simulation conclusion, by which the mechanisms of elevated stability of surfactant‐free O/W emulsion stabilized by the HMPAA comparing with PAA has been discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Novel Ni and Pd(benzocyclohexan‐ketonaphthylimino)2 complexes for copolymerization of norbornene with octene
Authors: Liu Yueman , Ouyang Meng , He Xiaohui , Chen Yiwang , Wang Kaiti
Published: June 2012

Two novel late transition metals complexes with bidentate OˆN chelate ligand, Mt(benzocyclohexan‐ketonaphthylimino)2 {Mt(bchkni)2: bchkni C10H8(O)C[N(naphthyl)CH3]; Mt  Ni, Pd}, were synthesized. In the presence of B(C6F5)3, both complexes exhibited high activity toward the homo‐polymerization of norbornene (NB) (as high as 2.7 × 105
gpolymer/molNi·h for Ni(bchkni)2/B(C6F5)3 and 2.3 × 105
gpolymer/molPd·h for Pd(bchkni)2/B(C6F5)3, respectively). Additionally, both catalytic systems showed high activity toward the copolymerization of NB with 1‐octene under various polymerization conditions and produced the addition‐type copolymer with relatively high molecular weights (0.1–1.4 × 105g/mol) as well as narrow molecular weight distribution. The 1‐octene content in the copolymers can be controlled up to 8.9–14.0% for Ni(bchkni)2/B(C6F5)3 and 8.8–14.6% for Pd(bchkni)2/B(C6F5)3 catalytic system by varying comonomer feed ratios from 10 to 70 mol %. The reactivity ratios of two monomers were determined to be r1‐octene = 0.052, rNB = 8.45 for Ni(bchkni)/B(C6F5)3 system, and r1‐octene = 0.025, rNB = 7.17 for Pd(bchkni)/B(C6F5)3 system by the Kelen‐TÜdÕs method. The achieved NB/1‐octene copolymers were confirmed to be noncrystalline and exhibited good thermal stability (Td > 400°C, Tg = 244.1–272.2°C) and showed good solubility in common organic solvents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Polypyrrole/graphene composite films synthesized via potentiostatic deposition
Authors: Lim Y. S. , Tan Y. P. , Lim H. N. , Tan W. T. , Mahnaz M. A. , Talib Z. A. , Huang N. M. , Kassim A. , Yarmo M. A.
Published: June 2012

A one‐step electrochemical process has been employed to synthesize composite films of polypyrrole/graphene (PPy/GR) by electrochemical polymerization on indium tin oxide (ITO) from an aqueous solution containing pyrrole monomer, graphene oxide (GO) nanosheets and sodium p‐toluenesulfonate (NapTS). Thermogravimetric analysis (TGA) confirmed the formation of a composite; the degradation temperature of the new hybrid was between those of PPy and GO. Moreover, the bulbous surface of PPy and the almost transparent tissue‐like GO nanosheets were replaced by the new appearance of the composite where the surface was flat but creased. As GO is nonconductive, we deduced that it had been reduced to conducting graphene in the composite film during the electrodeposition process, based on an electrical conductivity study measured with a four‐point probe. On average, the electrical conductivity of the PPy/GR composites was twofold higher than that of the pure PPy film, indicating that the incorporation of graphene was able to enhance the conductivity of PPy film. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of monomer composition on the properties of biodegradable poly(NIPAAm‐AA‐PCLdA) copolymeric hydrogels
Authors: Lee Wen‐Fu , Cheng Tzu‐Shen
Published: June 2012

A series of biodegradable hydrogels were prepared from N‐isopropylacrylamide (NIPAAm), acrylic acid (AA), and a biodegradable crosslinker, poly(caprolactone) diacrylate (PCLdA). The effect of the different molar ratios of NIPAAm and AA in the poly(NIPAAm‐co‐AA) copolymeric hydrogel on the swelling behaviors and physical properties were investigated. The results showed that the swelling ratio in deionized water and in phosphate buffer solution increased with an increase of the content of AA in the copolymeric hydrogel, and the critical gel transition temperature (CGTT) of the copolymeric hydrogel crosslinked with PCLdA was lower than the hydrogel crosslinked with N,N'‐methylenebisacrylamide (NMBA). The compressive modulus decreased with an increase of AA content in the copolymeric hydrogels. The gels showed good pH/temperature sensitive behavior. The results also showed that the hydrogel crosslinked with PCLdA has higher crosslinking density (ρx) and higher mechanical strength than the hydrogel crosslinked with NMBA. The influence of the copolymeric composition on the drug release behavior in the poly(NIPAAm‐co‐AA) hydrogels was also investigated in this study. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and characterization of nanohydroxyapatite strengthening nanofibrous poly(L‐lactide) scaffold for bone tissue engineering
Authors: Han Wanqing , Zhao Jianhao , Tu Mei , Zeng Rong , Zha Zhengang , Zhou Changren
Published: June 2012

A biomimetic nanofibrous poly(L‐lactide) scaffold strengthened by nanohydroxyapatite particles was fabricated via a thermally induced phase separation technique. Scanning electron microscopy results showed that nanohydroxyapatite particles uniformly dispersed in the nanofibrous poly(L‐lactide) scaffold (50–500 nm in fiber diameter) with slight aggregation at a high nHA content, but showed no influence on the interconnected macroporous and nanofibrous structure of the scaffold. The nanofibrous poly(L‐lactide) scaffold presented a specific surface area of 34.06 m2 g−1, which was much higher than that of 2.79 m2 g−1 for the poly(L‐lactide) scaffold with platelet structure. Moreover, the specific surface area of the nanofibrous scaffold was further enhanced by incorporating nanohydroxyapatite particles. With increasing the nanohydroxyapatite content, the compressive modulus and amount of bovine serum albumin adsorbed on the surface of the nanofibrous composite scaffold were markedly improved, as opposed to the decreased crystallinity. In comparison to poly(L‐lactide) scaffold, both the nanofibrous poly(L‐lactide) and poly(L‐lactide)/nanohydroxyapatite scaffolds exhibited a faster degradation rate for their much larger specific surface area. The culture of bone mesenchymal stem cell indicated that the composite nanofibrous poly(L‐lactide) scaffold with 50 wt % nanohydroxyapatite showed the highest cells viability among various poly(L‐lactide)‐based scaffolds. The strengthened biomimetic nanofibrous poly(L‐lactide)/nanohydroxyapatite composite scaffold will be a potential candidate for bone tissue engineering. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Individual magnetic resonance imaging and radiographic features of knee osteoarthritis in subjects with unilateral knee pain: The Health, Aging, and Body Composition Study
Authors: Javaid M. K. , Kiran A. , Guermazi A. , Kwoh C. K. , Zaim S. , Carbone L. , Harris T. , McCulloch C. E. , Arden N. K. , Lane N. E. , Felson D. , Nevitt M. ,   Health ABC Study
Published: June 2012

Objective

Strong associations between radiographic features of knee osteoarthritis (OA) and pain have been demonstrated in persons with unilateral knee symptoms. This study was undertaken to compare radiographic and magnetic resonance imaging (MRI) features of knee OA and assess their ability to discriminate between painful and nonpainful knees in persons with unilateral symptoms.

Methods

The study population included 283 individuals ages 70–79 years with unilateral knee pain who were enrolled in the Health, Aging, and Body Composition Study, a study of weight‐related diseases and mobility. Radiographs of both knees were read for Kellgren/Lawrence (K/L) grade and individual radiographic features, and 1.5T MRIs were assessed using the Whole‐Organ Magnetic Resonance Imaging Score. The association between structural features and pain was assessed using a within‐person case–control design and conditional logistic regression. Receiver operating characteristic (ROC) analysis was then used to test the discriminatory performance of structural features.

Results

In conditional logistic analyses, knee pain was significantly associated with both radiographic features (any joint space narrowing grade ≥1) (odds ratio 3.20 [95% confidence interval 1.79–5.71]) and MRI features (any cartilage defect scored ≥2) (odds ratio 3.67 [95% confidence interval 1.49–9.04]). However, in most subjects, MRI revealed osteophytes and cartilage and bone marrow lesions in both knees, and using ROC analysis, no individual structural feature discriminated well between painful and nonpainful knees. The best‐performing MRI feature (synovitis/effusion) was not significantly more informative than K/L grade ≥2 (P = 0.42).

Conclusion

In persons with unilateral knee pain, MRI and radiographic features were associated with knee pain, confirming that structural abnormalities in the knee have an important role in the etiology of pain. However, no single MRI or radiographic finding performed well in discriminating between painful and nonpainful knees. Further work is needed to examine how structural and nonstructural factors influence knee pain.
Porphyromonas gingivalis and disease‐related autoantibodies in individuals at increased risk of rheumatoid arthritis
Authors: Mikuls Ted R. , Thiele Geoffrey M. , Deane Kevin D. , Payne Jeffrey B. , O'Dell James R. , Yu Fang , Sayles Harlan , Weisman Michael H. , Gregersen Peter K. , Buckner Jane H. , Keating Richard M. , Derber Lezlie A. , Robinson William H. , Holers V. Michael , Norris Jill M.
Published: June 2012

Objective

To examine the relationship of Porphyromonas gingivalis to the presence of autoantibodies in individuals at risk of rheumatoid arthritis (RA).

Methods

Study participants included the following: 1) a cohort enriched in subjects with HLA–DR4 and 2) subjects at risk of RA by virtue of having a first‐degree relative with RA. None of the study subjects satisfied the American College of Rheumatology 1987 classification criteria for RA. Autoantibodies measured included anti–citrullinated protein antibody (ACPA; by second‐generation anti–cyclic citrullinated peptide antibody enzyme‐linked immunosorbent assay [ELISA]) and rheumatoid factor (RF; by nephelometry or ELISA for IgA, IgM, or IgG isotype). Individuals were considered autoantibody positive (n = 113) if they had ≥1 RA‐related autoantibody; individuals were further categorized as high risk (n = 38) if they had ACPA or positive findings ≥2 assays for RF. Autoantibody‐negative individuals (n = 171) served as a comparator group. Antibody to P gingivalis, P intermedia, and F nucleatum were measured. Associations of bacterial antibodies with group status were examined using logistic regression.

Results

Anti–P gingivalis concentrations were higher in high‐risk (P = 0.011) and autoantibody positive group (P = 0.010) than in the autoantibody negative group. There were no group differences in anti–P intermedia or anti–F nucleatum concentrations. After multivariable adjustment, anti–P gingivalis concentrations (but not anti–P intermedia or anti–F nucleatum) were significantly associated with autoantibody‐positive and high‐risk status (P < 0.05).

Conclusion

Immunity to P gingivalis, but not P intermedia or F nucleatum, is significantly associated with the presence of RA‐related autoantibodies in individuals at risk of RA. These results support the hypothesis that infection with P gingivalis may play a central role in the early loss of tolerance to self antigens that occurs in the pathogenesis of RA.