bluuebunny/crossref_metadata_2025 huggingface dataset:
The Meaning of Difference: Beyond Cultural and Managerial Homogeneity Stereotypes of Latin America
Authors: Friedrich Patricia , Mesquita Luiz , Hatum Andrés
Published: April 2010

Drawing from our current original research on cultural trends in Latin America‐based multinational firms, this paper challenges the stereotypical perception of Latin America as a homogeneous region and explores the cultural distances among groups of multinational employees. After collecting surveys from 733 employees across eight multinationals in Argentina, Brazil, Chile, Colombia, and Mexico, we establish that, much like it happens in other lumped‐together regions of the globe, such as “East Asia” and “Africa”, Latin American countries present significant differences in the way firm employees respond to situations where cultural traits are at stake. By researching these countries, we recorded significant variation in aspects such as the treatment and place of women in the workplace, attachment or detachment to formal rules, formal organizational hierarchies, and structured business planning, in addition to varying levels of tolerance to invasion of privacy. Implications of the study include the need to develop methodologies that adequately capture cultural differences within large geographic blocs and business practices that prepare the expatriate, the international manager, and the policy maker for the different realities they are bound to encounter in different countries.
Family history of hypertension as an important risk factor for the development of severe preeclampsia
Authors: BEZERRA PATRICIA C.F.M. , LEÃO MARCOS D. , QUEIROZ JOSÉ W. , MELO EDAILNA M.D. , PEREIRA FLÁVIO V.M. , NÓBREGA MARIA HEBE , JERONIMO ANA K. , FERREIRA LEONARDO C. , JERÔNIMO SELMA M.B. , DE ARAÚJO ANA CRISTINA P.F.
Published: April 2010

Objective. To determine the risk of preeclampsia in a population with respect to maternal and sister histories of chronic hypertension, preeclampsia and eclampsia. Design. A case‐control study of severe preeclampsia. Setting. Maternity hospital in Natal, Brazil. Participants. A total of 412 subjects were enrolled, 148 cases and 264 controls. Main outcome measures. Personal and familial histories of hypertensive disorders. Odds ratio estimates of preeclampsia with respect to family history of hypertensive diseases. Results. Women with a history of hypertensive disorders were more frequent in the case group (p = 0.001). Women whose mothers had a history of hypertension (p = 0.003), preeclampsia (p = 0.007) or eclampsia (p = 0.038) were at increased risk of severe preeclampsia. The risk of preeclampsia was greater when the woman had a sister with a history of hypertension (OR 2.60, 95% CI 1.60–4.21, p < 0.001), preeclampsia (OR 2.33, 95% CI 1.58–3.45, p < 0.001), or eclampsia (OR 2.57, 95% CI 1.28–5.16, p = 0.008). The risk of preeclampsia was also higher for women who had both a mother and sister with a history of hypertension (OR 3.65, 95% CI 1.65–8.09, p = 0.001). Conclusions. A family history of hypertensive disorders increased the risk of eclampsia and hemolysis elevated liver enzymes and low platelet (HELLP) syndrome in a Brazilian population.
Regulation of progesterone receptor A and B expression in human preterm, term, and postterm placental villi
Authors: ZIYAN JIANG , HUAIBIN REN , XIAOTIAN MA , GUANGTONG SHE , XIAOQING CHEN , ZIJIANG DONG , ZIYUE JIANG , WE DE , LIZHOU SUN
Published: April 2010

Objective. The progesterone receptor (PR)‐A/B ratio in the myometrium is reported to be closely related to labor onset. This might represent a potential target for therapeutic interventions for postterm and preterm deliveries, though the mechanisms currently remain unknown. The aim of this study was to investigate the regulation mechanism of PR‐A and B expression in human preterm, term, and postterm placental villi. Design. Experimental study. Setting. People's Hospital of Jiangsu Province, China. Population. Singleton women of preterm (PRNIL, not in labor, n = 10), term (TNIL, not in labor, n = 10; TIL, in labor, n = 10), and postterm (PONIL, not in labor, n = 10) cesarean deliveries. Methods. The PR‐A/PR‐B mRNA and protein ratios were analyzed using real‐time reverse transcription‐polymerase chain reaction and western blots in villi from preterm, term, postterm groups. PONIL and PRNIL villi were incubated with prostaglandin F2α (PG) and indomethacin for 72 hours, respectively, and the PR‐A/PR‐B mRNA and protein ratios and p38 signaling pathway were explored. Results. The PR‐A/PR‐B ratio was highest in TIL, followed by PRNIL, PONIL and TNIL. Indomethacin significantly up‐regulated PR‐B expression, thereby decreasing the PR‐A/PR‐B ratio (p < 0.05). Meanwhile, PG reduced the expression of PR‐B and increased PR‐A, leading to a significant increase in the PR‐A/PR‐B ratio (p < 0.05). We also determined that the PR‐A/PR‐B ratio was mediated through the activation of p38 mitogen‐activated protein kinase. Conclusion. These results demonstrate that the PR‐A/PR‐B ratio plays a key role in the mechanisms regulating preterm, term, and postterm deliveries.
Is ‘MILD’ sleep‐disordered breathing in women really mild?
Authors: ANTTALAINEN ULLA , POLO OLLI , SAARESRANTA TARJA
Published: April 2010

Sleep‐disordered breathing (SDB) consists of episodes of periodic obstructive or central sleep apnea and partial upper airway obstruction. The first two are well recognized and diagnosed, although still underdiagnosed. Traditionally, research in SDB has focused mainly on male patients with obstructive sleep apnea using apnea/hypopnea index (AHI) as a measure of severity. This has led to overrating of AHI as the only marker of SDB and underestimating of SDB in women. However, recently, partial upper airway obstruction has been acknowledged to be pathological and it may cause symptoms of SDB. There is a growing body of evidence that women suffer from SDB more than thought before and they especially have partial upper airway obstruction. Co‐morbidities such as cardiovascular diseases seem to be more prevalent in patients with SDB. This commentary points out some differences of SDB between genders in terms of symptoms and findings and emphasizes the clinical relevance of partial upper airway obstruction, especially in women.
Cultural Understanding of Non-timber Forest Products among the Babuban Community People of Eastern Nepal
Authors: Poudel Jiban Mani
Published: April 2010

This paper presents a short analysis of human-nature relationship among the Bahuban community people of eastern Nepal based on the use of non-timber forest products (NTFPs1). The paper basically describes perceptions and understanding of different categories of people towards NTFPs based on symbolic meaning and use-value of these products in their lives. In addition, the paper also shortly discusses indigenous practices for NTFPs management in the study area. DOI: 10.3126/opsa.v11i0.3034 Occasional Papers in Sociology and Anthropology Vol.11 2009 126-147
Perceptions and Practices of Society Towards Single Women in the Context of Nepal
Authors: Uprety Mina , Adhikary Sikshya
Published: April 2010

The purpose of this paper is to highlight on the perceptions and practices of society towards single women, specifically the widows, in the context of Nepal. The focus is on issues of gender relations and the status of widow women. The arguments are based on the review of literature and the author's own observation of social practices towards women and widow women. The discussion starts by defining the concept of women and single women and proceeds through the discussion of their status in relation to men as they are prescribed by codes of conduct of society. DOI: 10.3126/opsa.v11i0.3039 Occasional Papers in Sociology and Anthropology Vol.11 2009 244-254
Microbial Fuel Cells, A Current Review
Authors: Franks Ashley E. , Nevin Kelly P.
Published: April 2010

Microbial fuel cells (MFCs) are devices that can use bacterial metabolism to produce an electrical current from a wide range organic substrates. Due to the promise of sustainable energy production from organic wastes, research has intensified in this field in the last few years. While holding great promise only a few marine sediment MFCs have been used practically, providing current for low power devices. To further improve MFC technology an understanding of the limitations and microbiology of these systems is required. Some researchers are uncovering that the greatest value of MFC technology may not be the production of electricity but the ability of electrode associated microbes to degrade wastes and toxic chemicals. We conclude that for further development of MFC applications, a greater focus on understanding the microbial processes in MFC systems is required.
Effects of Native Banana Starch Supplementation on Body Weight and Insulin Sensitivity in Obese Type 2 Diabetics
Authors: Ble-Castillo Jorge L. , Aparicio-Trápala María A. , Francisco-Luria Mateo U. , Córdova-Uscanga Rubén , Rodríguez-Hernández Arturo , Méndez José D. , Díaz-Zagoya Juan C.
Published: April 2010

Few fiber supplements have been studied for physiological effectiveness. The effects of native banana starch (NBS) and soy milk (control) on body weight and insulin sensitivity in obese type 2 diabetics were compared using a blind within-subject crossover design. Subjects undertook two phases of 4-week supplementation either with NBS or soy milk. Patients on NBS lost more body weight than when they were on control treatment. Plasma insulin and HOMA-I were reduced after NBS consumption, compared with baseline levels, but not significantly when compared to the control treatment. Results support the use of NBS as part of dietary fiber supplementation.
Autism from a Biometric Perspective
Authors: Kostyuk Nataliya , Rajnarayanan Rajendram V. , Isokpehi Raphael D. , Cohly Hari H.
Published: April 2010

Purpose:The aim of this pilot study was to test autistic children, siblings and their parents using a biometric device based on the gas discharge visualization (GDV) technique in order to assess their psycho-emotional and physiological functional state based on the activity of the autonomic nervous system. Hypothesis: We hypothesize that the biometric assessment based on GDV will enable us: (1) to evaluate some specific features associated with autism spectrum disorder (ASD) as well as to compare autistic children to their siblings and to controls; (2) to analyze the differences in individual values of parents of autistic children versus parents of normal children. Results: Out of total of 48 acupuncture points present on ten fingertips of both hands and associated to organs/organ systems, autistic children differed significantly from controls (p < 0.05) in 36 (images without filter) and 12 (images with filter), siblings differed significantly from controls (p < 0.05) in 12 (images without filter) and seven (images with filter), autistic children differed significantly (p < 0.05) from siblings in eight (images without filter) and one (images with filter), fathers of autistic children differed significantly (p < 0.05) from controls in 14 (images without filter) and three (images with filter) and mothers of autistic children differed significantly (p < 0.05) from controls in five (images without filter) and nine (images with filter) acupuncture points. Conclusions: All compared groups have shown significant difference on both psycho-emotional (images without filter) and physiological (images with filter) levels. However, the differences between autistic children and controls expressed on psycho-emotional level were the most significant as compared to the other groups. Therefore, the activity of the sympathetic autonomic nervous system is significantly altered in children with autism. The biometric method based on GDV is a promising step in autism research that may lead towards creating a disease profile and identify unique signature/biomarker for autism. Further work should involve more participants in order to augment our findings.
Arsenic Trioxide Modulates DNA Synthesis and Apoptosis in Lung Carcinoma Cells
Authors: Walker Alice M. , Stevens Jacqueline J. , Ndebele Kenneth , Tchounwou Paul B.
Published: April 2010

Arsenic trioxide, the trade name Trisenox, is a drug used to treat acute promyleocytic leukemia (APL). Studies have demonstrated that arsenic trioxide slows cancer cells growth. Although arsenic influences numerous signal-transduction pathways, cell-cycle progression, and/or apoptosis, its apoptotic mechanisms are complex and not entirely delineated. The primary objective of this research was to evaluate the effects of arsenic trioxide on DNA synthesis and to determine whether arsenic-induced apoptosis is mediated via caspase activation, p38 mitogen–activated protein kinase (MAPK), and cell cycle arrest. To achieve this goal, lung cancer cells (A549) were exposed to various concentrations (0, 2, 4, 6, 8, and 10 µg/mL) of arsenic trioxide for 48 h. The effect of arsenic trioxide on DNA synthesis was determined by the [3H]thymidine incorporation assay. Apoptosis was determined by the caspase-3 fluorescein isothiocyanate (FITC) assay, p38 MAP kinase activity was determined by an immunoblot assay, and cell-cycle analysis was evaluated by the propidium iodide assay. The [3H]thymidine-incorporation assay revealed a dose-related cytotoxic response at high levels of exposure. Furthermore, arsenic trioxide modulated caspase 3 activity and induced p38 MAP kinase activation in A549 cells. However, cell-cycle studies showed no statistically significant differences in DNA content at subG1 check point between control and arsenic trioxide treated cells.
Advances in Porous Biomaterials for Dental and Orthopaedic Applications
Authors: Mour Meenakshi , Das Debarun , Winkler Thomas , Hoenig Elisa , Mielke Gabriela , Morlock Michael M. , Schilling Arndt F.
Published: April 2010

The connective hard tissues bone and teeth are highly porous on a micrometer scale, but show high values of compression strength at a relatively low weight. The fabrication of porous materials has been actively researched and different processes have been developed that vary in preparation complexity and also in the type of porous material that they produce. Methodologies are available for determination of pore properties. The purpose of the paper is to give an overview of these methods, the role of porosity in natural porous materials and the effect of pore properties on the living tissues. The minimum pore size required to allow the ingrowth of mineralized tissue seems to be in the order of 50 µm: larger pore sizes seem to improve speed and depth of penetration of mineralized tissues into the biomaterial, but on the other hand impair the mechanical properties. The optimal pore size is therefore dependent on the application and the used material.
Long Term Fatigue Behavior of Zirconia Based Dental Ceramics
Authors: Aboushelib Moustafa N.
Published: April 2010

This study evaluated the influence of cyclic loading on zirconia bar-shaped specimens after being subjected to three different surface treatments: particle abrasion with either 50 μm or 110 μm alumina and grinding with diamond points, while polished specimens served as a control. Statistical analysis revealed significant reduction (38-67%) in flexure strength (P < 0.001) after three million cycles of dynamic loading for all surface treatments. Scanning electron imaging revealed grain boundary thickening, grain pull-out, and micro-cracking as the main structural defects. The results suggest that various surface treatments of zirconia based dental ceramics may significantly influence their long term fatigue resistance in the oral environment.
Chitin and Chitosan as Multipurpose Natural Polymers for Groundwater Arsenic Removal and As2O3 Delivery in Tumor Therapy
Authors: Da Sacco Letizia , Masotti Andrea
Published: April 2010

Chitin and chitosan are natural polysaccharide polymers. These polymers have been used in several agricultural, food protection and nutraceutical applications. Moreover, chitin and chitosan have been also used in biomedical and biotechnological applications as drug delivery systems or in pharmaceutical formulations. So far, there are only few studies dealing with arsenic (As) removal from groundwater using chitin or chitosan and no evidence of the use of these natural polymers for arsenic trioxide (As2O3) delivery in tumor therapy. Here we suggest that chitin and/or chitosan might have the right properties to be employed as efficient polymers for such applications. Besides, nanotechnology offers suitable tools for the fabrication of novel nanostructured materials of natural origin. Since different nanostructured materials have already been employed successfully in various multidisciplinary fields, we expect that the integration of nanotechnology and natural polymer chemistry will further lead to innovative applications for environment and medicine.
The Role of Non-Steroidal Anti-Inflammatory Drugs in Renal Colic
Authors: Davenport Kim , Waine Elizabeth
Published: April 2010

NSAIDs provide optimal analgesia in renal colic due to the reduction in glomerular filtration and renal pelvic pressure, ureteric peristalsis and ureteric oedema. Prevention of glomerular afferent arteriolar vasodilatation renders these patients at risk of renal impairment. NSAIDs have the additional benefit of reducing the number of new colic episodes and preventing subsequent readmission to hospital. Despite recent work promoting the use of pharmacological agents to improve stone passage rates, NSAIDs do not appear to reduce the time to stone passage or increase the likelihood of stone passage in renal colic.
Prospects for the Use of ATR Inhibitors to Treat Cancer
Authors: Wagner Jill M. , Kaufmann Scott H.
Published: April 2010

ATR is an apical kinase in one of the DNA-damage induced checkpoint pathways. Despite the development of inhibitors of kinases structurally related to ATR, as well as inhibitors of the ATR substrate Chk1, no ATR inhibitors have yet been developed. Here we review the effects of ATR downregulation in cancer cells and discuss the potential for development of ATR inhibitors for clinical use.
Real-Time Time-Frequency Two-Dimensional Imaging of Ultrafast Transient Signals in Solid-State Organic Materials
Authors: Takeda Jun , Ishida Akihiro , Makishima Yoshinori , Katayama Ikufumi
Published: April 2010

In this review, we demonstrate a real-time time-frequency two-dimensional (2D) pump-probe imaging spectroscopy implemented on a single shot basis applicable to excited-state dynamics in solid-state organic and biological materials. Using this technique, we could successfully map ultrafast time-frequency 2D transient absorption signals of β-carotene in solid films with wide temporal and spectral ranges having very short accumulation time of 20 ms per unit frame. The results obtained indicate the high potential of this technique as a powerful and unique spectroscopic tool to observe ultrafast excited-state dynamics of organic and biological materials in solid-state, which undergo rapid photodegradation.
Surf and Turf: Mechanism of Enhanced Virus Spread During Poxvirus Infection
Authors: Condit Richard C.
Published: April 2010

Commentary on Doceul, V.; Hollinshead, M.; van der Linden, L.; Smith, G.L. Repulsion of superinfecting virions: a mechanism for rapid virus spread. Science 2010, 327, 873-876.
Reactividad álcali-sílice y álcali-silicato en pizarras
Authors: Campos P.L. , Gadea J. , Soriano J. , Martín A. , Calderón V.
Published: April 2010

En este trabajo se ha estudiado la reactividad de las pizarras con los hidróxidos alcalinos liberados por los cementos en hormigones y morteros. Para ello se han realizado diferentes ensayos en distintas condiciones, a una selección de pizarras de distinto origen y composición. Se ha constatado que todas las pizarras ensayadas son susceptibles de sufrir reactividad álcali-sílice álcali-silicato con los álcalis de los cementos y que no todos los ensayos que se realizan de forma rutinaria para detectar este tipo de reacciones en los áridos son igual de fiables. Comprobada la reactividad de estas rocas se estudian las causas de los comportamientos observados y las posibilidades de minimizar o eliminar estas reactividades de tal manera que se puedan utilizar las pizarras en contacto con los cementos en materiales compuestos. El uso de cementos puzolánicos se revela como eficaz a la hora de eliminar este tipo de reacciones.
Geocronología isotópica de rocas graníticas de la Zona Centro-Ibérica: comparación de metodologías
Authors: Antunes I. M.H.R. , Neiva A. M.R. , Silva M. M.V.G.
Published: April 2010

En el plutón de Castelo Branco, se distinguen cinco granitoides, dispuestos concéntricamente de núcleo a borde del plutón. Las edades U-Pb-Th obtenidas en cristales de monacita por microsonda electrónica en estos granitoides son similares entre sí y varían entre 297 y 303 Ma. Los resultados de datación por U-Pb (ID-TIMS) en cristales de circón y de monacita de los tres granitos seleccionados, indican una edad de implantación de 310 ± 1 Ma y que son rocas emplazadas simultáneamente. Las relaciones isotópicas iniciales de 87Sr/86Sr y los valores de εNd310 y δ18O de los tres pulsos magmáticos son característicos de granitos resultantes de anatexia cortical a partir de rocas metasedimentarias heterogéneas. En la secuencia de diferenciación magmática, las rocas graníticas presentan pequeñas variaciones en (87Sr/86Sr)310, εNd310 y δ18O. El plutón de Castelo Branco presenta un zonado inverso poco frecuente.
Adenofibroma of Skene's Duct: A Case Report
Authors: Chong Yosep , Eom Minseob , Park Kwang Hwa , Chung Hyun Chul , Ro Jae Y.
Published: April 2010

Skene's glands, also known as paraurethral glands, are homologues of the male prostate, in which painless cystic masses and inflammation due to obstruction have been rarely found and reported. In addition, there have been rare reported cases of adenocarcinoma of Skene's glands. Recently, the authors experienced the first case of adenofibroma arising in Skene's glands of a 62-year-old woman with coital pain. Hereby, we present the case with pathologic and immunohistochemical findings and a short review of literature.
Interaction between oxidative stress and high‐density lipoprotein cholesterol is associated with severity of coronary artery calcification in rheumatoid arthritis
Authors: Rho Young Hee , Chung Cecilia P. , Oeser Annette , Solus Joseph F. , Gebretsadik Tebeb , Shintani Ayumi , Raggi Paolo , Milne Ginger L. , Stein C. Michael
Published: April 2010

Objective

To test the hypothesis that oxidative stress is increased in patients with rheumatoid arthritis (RA) due to increased inflammation and contributes to the pathogenesis of atherosclerosis.

Methods

The independent association between urinary F2‐isoprostane excretion, a measure of oxidative stress, and RA was tested using multiple linear regression models in 169 patients with RA and 92 control subjects, frequency matched for age, race, and sex. The relationship between F2‐isoprostane excretion and coronary calcium, a marker of atherosclerosis, was examined in multivariable proportional odds logistic regression models that also assessed the interactions between oxidative stress and low‐density lipoprotein and high‐density lipoprotein (HDL) cholesterol.

Results

F2‐isoprostane excretion was significantly higher in patients with RA (median 2.75 [interquartile range (IQR) 1.60–4.06] ng/mg creatinine) than in control subjects (median 1.86 [IQR 1.25–2.62] ng/mg creatinine; adjusted P = 0.006). In patients with RA, F2‐isoprostanes were positively correlated with body mass index (P < 0.001), but not with disease activity or mediators of inflammation such as the Disease Activity Score in 28 joints or serum tumor necrosis factor α, interleukin‐6, and C‐reactive protein concentrations in adjusted multivariable models (P > 0.05 for all). In patients with RA, F2‐isoprostanes significantly modified the effect of HDL cholesterol on coronary calcification (P = 0.02 for interaction) after adjustment for age, sex, and race. As F2‐isoprostane levels increased, HDL lost its protective effect against coronary calcification.

Conclusion

Oxidative stress measured as F2‐isoprostane excretion was higher in patients with RA than in control subjects. Among patients with RA, higher F2‐isoprostane excretion and HDL cholesterol concentrations interacted significantly and were positively associated with the severity of coronary calcification.
Photoswitches: From Molecules to Materials
Authors: Russew Maria‐Melanie , Hecht Stefan
Published: April 2010

Small organic molecules, capable of undergoing efficient and reversible photochemical reactions to switch them between (at least) two (meta)stable isomers associated with markedly different properties, continue to impact the materials world. Such photoswitches are being implemented in a variety of materials for applications ranging from optical devices to “smart” polymers. All approaches exploit the photoswitching molecular entities as gates, which translate an incoming light stimulus to trigger macroscopic property changes of the materials. In this progress report, the most promising recent examples in this field are highlighted and put in perspective. Moving from supramolecular systems in solution to surfaces and finally to bulk materials, important design concepts are discussed, emphasizing both the challenges as well as the great promise of such truly advanced materials.
Pericytes and vessel maturation during tumor angiogenesis and metastasis
Authors: Raza Ahmad , Franklin Michael J. , Dudek Arkadiusz Z.
Published: April 2010

Despite promising results in preclinical and clinical studies, the therapeutic efficacy of antiangiogenic therapies has been restricted by a narrow focus on inhibiting the growth of endothelial cells. Other cell types in the tumor stroma are also critical to the progression of cancer, including mural cells. Mural cells are vascular support cells that range in phenotype from pericytes to vascular smooth muscle cells. Although the role of pericytes and pericyte‐like cells in the pathophysiology of cancer is still unclear, evidence indicates that aberrations in pericyte–endothelial cell signaling networks could contribute to tumor angiogenesis and metastasis. The purpose of this review is to evaluate critically recent evidence on the role of pericytes in tumor biology and discuss potential therapeutic targets for anticancer intervention. Am. J. Hematol. 85:593–598, 2010. © 2010 Wiley‐Liss, Inc.
Preparation and mechanical properties of crosslinked 1,2,3‐triazole‐polymers as potential propellant binders
Authors: Wang Ling , Song Yuming , Gyanda Reena , Sakhuja Rajeev , Meher Nabin K. , Hanci Sureyya , Gyanda Kapil , Mathai Sindhu , Sabri Firouzeh , Ciaramitaro David A. , Bedford Clifford D. , Katritzky Alan R. , Duran Randolph S.
Published: April 2010

Thirteen triazole polymers were prepared as potential rocket propellant binders by the reactions of various diacetylenes and diazides. The reaction of E300 dipropiolate (1) with diazide (2) obtained from tetraethylene glycol was selected to study the effects of concentration of the tetraacetylene functionalized crosslinker (3) on the mechanical properties of resulting triazole polymers. The modulus of the polymers increased, whereas the strain (% elongation at failure) decreased with increasing percentage of crosslinker. The resulting triazole polymers also showed that the desired mechanical properties could be obtained by adjusting the crosslinker concentration during the polymerization. Addition of 43 wt % aluminum filler did not significantly affect the strain. The modulus of these triazole polymers was comparable with typical polyurethane elastomeric matrices for rocket propellants. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of carbon black addition and its phase selective distribution on the stress relaxation behavior of filled thermoplastic vulcanizates
Authors: Le Hai Hong , Heidenreich Daniel , Kolesov Igor S. , Ilisch Sybill , Radusch Hans‐Joachim
Published: April 2010

The long term mechanical behavior of thermoplastic vulcanizates (TPV) based on polypropylene (PP) and ethylene propylene diene terpolymer (EPDM) and different types and concentrations of carbon black (CB) has been characterized by means of stress relaxation experiments. Evaluation of the relaxation curves was carried out using the two‐component model allowing a division of the initial stress into different stress components which are caused by different networks available in TPV. The discussion focussed on the background of the stress components, which are originated by the CB addition, the non‐relaxing stress components σ, and σ, as well as the relaxing stress components ΔσCB(polymer‐layer) and ΔσCB(network). It was found that the concentration and type of CB as well as the phase specific CB distribution strongly affect the non‐relaxing and relaxing stress components. Up to a CB concentration of 9% in the EPDM phase the composite behaves as a thermo‐rheologically simple material because the impact of CB addition on the α‐relaxation of the crystalline PP phase is still negligible. A master curve was created by the horizontal shift of the relaxing stress curves ΔσComp(t) to a reference curve. At higher local CB loadings the additional relaxation processes induced by CB addition overlap with the α‐relaxation, thus, no master curve could be made in that case. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nonlinear optical studies on new conjugated poly{2,2l‐(3,4‐ dialkoxythiophene‐2,5‐diyl) bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s
Authors: Hegde Pramod Kumar , Adhikari A. Vasudeva , Manjunatha M. G. , Sandeep C. S. Suchand , Philip Reji
Published: April 2010

Three new donor–acceptor type poly{2,2l‐(3,4‐ dialkoxythiophene‐2,5‐diyl)bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s (P1, P2, and P3) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge‐transporting properties of the polymers were investigated by UV‐visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish‐green fluorescence in solutions. The electrochemical band gaps were determined to be 2.03, 2.09, and 2.17 eV for P1, P2, and P3, respectively. The nonlinear optical properties of new polymers were investigated at 532 nm using single beam Z‐scan and degenerate four‐wave mixing (DFWM) techniques with nanosecond laser pulses. The polymers exhibited strong optical limiting behavior due to “effective” three‐photon absorption. Values of the effective three‐photon absorption (3PA) coefficients, third‐order nonlinear susceptibilities (χ(3)), and figures (F) of merit were calculated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Phase‐separation process in a poly(methyl methacrylate)‐modified epoxy system: A novel approach to understanding the effect of the curing temperature on the final morphology
Authors: Olmos D. , Loayza A. , González‐Benito J.
Published: April 2010

In this study, the physical and chemical changes of a poly(methyl methacrylate) (PMMA)‐modified epoxy system were examined to understand the effect of the curing conditions on its final morphology. The curing process of the PMMA–epoxy reactive system was complementarily analyzed by Fourier transform infrared spectroscopy in the near range (FT‐NIR) and fluorescence spectroscopy. The relationships among (1) the chemical conversion of the curing reaction, (2) the first moment of the fluorescence emission band (〈ν〉) arising from a chromophore chemically bonded to the epoxy reactive system, (3) the phase‐separation process, and (4) the dynamics of the epoxy thermoset during its curing process are discussed. From a chemical point of view, FT‐NIR did not reveal any significant change in the curing reaction with the presence of 2 wt % PMMA. However, in terms of physical changes, the analysis of the fluorescence response clearly showed variations in the curing reaction due to the presence of the thermoplastic polymer. Also, fluorescence allowed the estimation of the glass‐transition temperature of the system with curing when the reaction was diffusion‐controlled, whereas Fourier transform infrared spectroscopy was not sensible enough. In the second part of this study, scanning electron microscopy images of the PMMA‐modified epoxy system were analyzed to understand the effect of the temperature on the final morphology when the amount of thermoplastic was below the critical volume fraction. A linear dependence between the inverse of the mean area of the thermoplastic‐rich domains and the inverse of the absolute temperature was obtained. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Evaluation of the chemical resistance of high‐density polyethylene geomembranes
Authors: Yoo Hankyu , Jeon Han‐Yong , Lee Kwangyeol , Yoo Chungsik , Herath C. N.
Published: April 2010

The chemical resistance of high‐density polyethylene geomembranes (GMs) with smooth and textured surfaces in notched and unnotched forms at different pH values and in the range of 20–80°C was examined with stress crack resistance testing. Surface microcracks in GMs were observed in scanning electron microscopy images. Smooth and textured GMs did not show significant differences in their mechanical behaviors. The yield strength decreased with the temperature, pH, and exposure time. The yield strain increased with the temperature, but there were no good correlations with pH values. The break strength also decreased with the temperature and showed no significant correlation with pH variations. The break strain did not show a good correlation with the temperature and pH variations. The stress crack resistance was independent of pH variations but significantly depended on the temperature. It was negatively correlated with the exposure time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Highlight of a compensation effect between filler morphology and loading on dynamic properties of filled rubbers
Authors: Sosson Franck , Belec Lénaïk , Chailan Jean‐François , Carriere Pascal , Crespy Alain
Published: April 2010

This investigation highlighted the equivalence between carbon black (CB) loading and structure influences on dynamic mechanical properties in the linear behavior of several filled synthetic rubber compounds. Different morphologies (specific surface area and structure) of CB incorporated at different loadings were formulated to modulate the filler‐rubber matrix interphase content, usually named “tightly bound rubber.” Both reinforcement level and tightly bound rubber content were measured on each compound by dynamic mechanical analysis (DMTA) and by Soxhlet extraction and thermogravimetry (TGA) respectively. Then, a systematic description of their evolution was made against CB loading and morphology. These evolutions were attributed to the hydrodynamic effect which could be evaluated by the effective filler volume fraction. A new parameter κ is defined, representing the effective filler volume fraction for each compound and it was calculated on the basis of experimental parameters. Results show good correspondences between κ included both the hydrodynamic effects of the filled carbon black rubbers and dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Properties of green SrAl2O4 phosphor in LDPE and PMMA polymers
Authors: Bem D.B. , Swart H.C. , Luyt A.S. , Coetzee E. , Dejene F.B.
Published: April 2010

Different contents of SrAl2O4:Eu,Dy, one of the long afterglow phosphorescent materials with high brightness, were melt‐mixed with low‐density polyethylene (LDPE) and Polymethyl methacrylate (PMMA) polymers, respectively. The morphology and composition of the samples were observed by means of a scanning electron microscope (SEM) coupled with an energy dispersive spectrometer (EDS), X‐ray diffractometer (XRD), and transmission electron microscope (TEM). Sharp and broad X‐ray diffraction (XRD) peaks were observed for the LDPE and the PMMA composites respectively, reflecting configuration characteristics similar to those of the respective pure polymers. TEM micrographs show a transition from nanosized particles to cluster formation with increase in phosphor concentration. The green long‐lasting phosphorescence of the composites was observed in the dark after removal of the excitation light. Photoluminescence (PL) was observed in the composites of both polymers for phosphor volume concentrations above 1.0% for PMMA and above 0.5% for LDPE. For each of these samples, a broad PL peak at about 505 nm wavelength was observed after excitation at 350 nm with a xenon lamp. For the LDPE composites, the DSC results show that the presence of the phosphor in the polymer has no major influence on either the melting temperature or enthalpy values of the polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of polymer microspheres in supercritical carbon dioxide and their evaluation as cold‐flow improvers in diesel
Authors: Zhang Donghui , Cui Leyu , Wei Xiangpan , Zhang Shubiao
Published: April 2010

Polymeric microspheres were synthesized by the precipitation copolymerization of methacrylic acid and styrene in supercritical carbon dioxide. Scanning electron microscopy showed that the products were spherical microparticles. The mean diameter of the particles was 0.2–2 μm. The synthesis conditions affecting the particle size and morphology were examined in detail. The well‐distributed copolymer microspheres were applied as low‐temperature improvers for diesel. The results showed excellent performance for high‐paraffin diesel at low temperatures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of aclarubicin PLGA nanospheres and related in vitro/in vivo studies
Authors: Han Bing , Gao Shi‐Zhu , Zhang Xiao‐Hong , Tian Hong‐Bing , Wang Hao‐Tian , Shang Zu‐Hui
Published: April 2010

The microencapsulation method was used to prepare formulations of the anthracycline drug aclarubicin, and the effects of a variety of different conditions on the preparation process were evaluated. The drug was entrapped in poly(lactic‐co‐glycolic acid) (PLGA) to prepare an aclarubicin nanosphere formulation that could be sustainably released, and had a high drug loading capacity and high entrapment efficiency. The degree of degradation of aclarubicin PLGA nanospheres that were prepared under different conditions was tested in vitro. Aclarubicin nanospheres that were intravenously injected into rabbits were found to be slowly and stably released over a period of almost 20 days. HPLC was used to determine the blood concentrations of the products. To provide pharmacodynamic and toxicologic profiles, the aclarubicin PLGA nanospheres were intravenously injected into mice. The results showed that the aclarubicin PLGA nanospheres exerted anti‐tumor activity in vivo, but did not produce toxic effects that were more serious than those resulting from the standard administration of aclarubicin agents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Distribution of morphology and transport properties of water vapor in injection‐molded biodegradable aliphatic polyester
Authors: Partini Maria , Gorrasi Giuliana , Pantani Roberto
Published: April 2010

A biodegradable polyester, poly(tetramethylene dodecanedioate), was injection molded in a rectangular cavity. Thin sections were sliced from molded samples starting from the skin. The morphology distribution inside the molded samples was studied by X‐ray analysis. The diffusion and solubility coefficient of water vapor were then measured using the microgravimetric method at the temperature of 30°C. Results show that morphology developed during the process influences the diffusion of water molecules through the polymer matrix. In particular, a direct influence of crystalline degree on the sorption and diffusion parameters was identified. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Study on chain deformation of polyacrylamides in solutions and its flocculation performance during the flocculation process
Authors: Gui Z. L. , Qian J. W. , Li X. K. , Zheng B. Q. , An Q. F.
Published: April 2010

Effects of external conditions, solution concentration, solvent quality, added salt, and pH on the chain conformation dimension of two kinds of polyacrylamide (PAAm) flocculants, neutral‐PAAm, and cationic‐P(AAm‐DMC) (DMC, 2‐[(methacryloyloxy)ethyl] trimethylammonium chloride), in parent solutions and their flocculation performance for Kaolin suspensions have been investigated by Ubbelohde viscometer and spectrophotometer, respectively. It was found that a negative correlation existed between the flocculation performance of PAAm flocculants and their chain sizes in parent solutions. This was attributed to the expanded chain deformation of PAAm flocculants during the flocculation process from the flocculant parent solution to the Kaolin suspension and was interpreted in term of the competitive interaction among the polymeric flocculant, solvent, and Kaolin particle in the chain deformation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
An effective antimicrobial treatment for wool using polyhexamethylene biguanide as the biocide, part 2: Further characterizations of the fabrics
Authors: Gao Yuan , Cranston Robin
Published: April 2010

Part 1 of this study reported an effective antimicrobial treatment for wool, using a pretreatment of peroxymonosulfate and sulfite to facilitate the exhaustion of polyhexamethylene biguanide (PHMB), a biocide with a long history of safe use. Here, further studies were performed to examine whether this finishing would satisfy the requirements for commercial antimicrobial textile production in terms of washing durability, its compatibility with dyeing and its effects on textile physical properties. The finishing was found to be very durable, sustaining at least 25 washing cycles without significant reduction in the antimicrobial activity. The process was compatible with reactive dyes, although other types of dyes (acid dyes, chrome dyes, and Premetalized dyes) all reduced PHMB uptake by ∼ 50%. The finishing had little adverse effect on the tensile strength, handle or whiteness of the fabrics. This process therefore meets the requirements of and holds promise for the commercial production of antimicrobial wool textiles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Controlled preparation of physically crosslinked chitosan‐g‐poly(vinyl alcohol) hydrogel
Authors: Xiao Congming , Gao Feng , Gao Yongkang
Published: April 2010

Physically crosslinked chitosan‐g‐poly(vinyl alcohol) hydrogels with controllable graft percent were prepared in three steps. Poly(vinyl acetate) (PVAc) was first grafted onto chitosan via radical copolymerization. Then the copolymer was converted into chitosan‐g‐poly(vinyl alcohol) by alcoholysis reaction. The graft percent of poly (vinyl alcohol) (PVA) could be tailored by the reaction conditions such as the solvent composition, the concentration of initiator and the amount of monomer added. Finally, Chitosan‐g‐PVA hydrogels were formed by freezing‐thawing cycles. The structure of graft copolymers was verified with FTIR. Both XRD analysis and contact angle test showed that the difference of crystallinity and hydrophilicity among chitosan, chitosan‐g‐PVAc and chitosan‐g‐PVA was evident. It was found that the maximum swelling ratios of chitosan‐g‐PVA hydrogels containing 37.6% and 46.2% PVA were 3.48 ± 0.11 and 4.40 ± 0.14 at pH 1.2, 1.90 ± 0.13 and 2.80 ± 0.15 at pH 7.4, respectively. This suggested the hydrogel was pH‐sensitive, and its swelling behavior could be tailored with the graft percent of PVA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Degradation of the covalent carbon–carbon bond between fullerene‐C60 and poly(1,3‐cyclohexadiene)
Authors: Natori Itaru , Natori Shizue
Published: April 2010

The degradation of fullerene‐C60 (C60) end‐capped poly(1,3‐cyclohexadiene) (C60‐PCHD) with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) was examined to reveal the nature of the covalent carbon–carbon bond between C60 and PCHD (C60‐PCHD bond). The number average molecular weight (Mn) of C60‐PCHD decreased with an increase in the degree of dehydrogenation, and the elimination of a PCHD arm from a C60 occurred. The degradation of the C60‐PCHD bond via a 1,4‐CHD unit was faster than that via a 1,2‐CHD unit, whereas the C60‐poly(cyclohexane) bond was stable. The degradation of the C60‐PCHD bond with DDQ was caused by the dehydrogenation of a CHD unit adjoining a C60 core. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Tensile and lignocellulosic properties of Prosopis chilensis natural fabric
Authors: Reddy G. Venkata , Prasad C.Venkata , Rao K. Chowdoji , Rani T. Sobha , Subha M. C. S.
Published: April 2010

The uniaxial natural fabric Prosopis chilensis was treated with NaOH (alkali), poly (vinyl alcohol) (PVA), and polycarbonate (PC) solutions. The Prosopis chilensis fabric belongs to Leguminosae family. The properties of ligno‐cellulosic fabric and the effect of sodium hydroxide (NaOH) treatment were evaluated using thermal analysis by means of thermogravimetric and differential scanning calorimetry analysis, Autonated total reflection‐fourier transform infrared spectroscopy, X‐ray diffraction (XRD), and field emission scanning electron microscopy. Tensile properties of the untreated and fabric treated with NaOH, PVA, and PC were also studied to assess their performance. The fabric has good thermal resistance on alkali treatment. The FTIR method indicates lowering the hemi cellulose and lignin content by alkali treatment. Further, the XRD studies reveal that crystallinity of the fabric increases on alkali treatment. Tensile properties of the fabric were enhanced on treatments with NaOH, PVA, and PC treatments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hebephilia: Quintessence of diagnostic pretextuality
Authors: Franklin Karen
Published: April 2010

Hebephilia is an archaic term used to describe adult sexual attraction to adolescents. Prior to the advent of contemporary sexually violent predator laws, the term was not found in any dictionary or formal diagnostic system. Overnight, it is on the fast track toward recognition as a psychiatric condition meriting inclusion in the upcoming fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. This article traces the sudden emergence and popularity of hebephilia to pressure from the legal arena and, specifically, to the legal mandate of a serious mental abnormality for civil commitment of sex offenders. Hebephilia is proposed as a quintessential example of pretextuality, in which special interests promote a pseudoscientific construct that furthers an implicit, instrumental goal. Inherent problems with the construct's reliability and validity are discussed. A warning is issued about unintended consequences if hebephilia or its relative, pedohebephilia, make their way into the DSM‐5, due out in 2013. Copyright © 2010 John Wiley & Sons, Ltd.