bluuebunny/crossref_metadata_2025 huggingface dataset:
La crisis de la política científica: patologías degenerativas y terapias regenerativas. A modo de epílogo
Authors: Muñoz Emilio
Published: June 2009

La aplicación de una analogía como ser vivo e inteligente a la política científica ha permitido identificar lo que he llamado “crisis” de esa política, como resultado de un proceso de envejecimiento –hace más de sesenta años que se inició la política científica moderna– en el que han intervenido una serie de patologías que han sido diagnosticadas a través de una serie de revisiones críticas emprendidas por el autor dentro del marco de un programa sobre “filosofía de la política científica”. A través del recurso a metáforas médicas y clínicas he podido construir una historia clínica en la que se describen las patologías y sus diagnósticos, asociadas simbólicamente a trastornos mentales y sensoriales. Entre ellos cabe mencionar procesos de amnesia, del que es un ejemplo la disociación entre lenguaje y acción motora (discurso y acción); la deficiente comprensión de conceptos en el trinomio básico I+D+innovación y de las relaciones entre ellos; frecuentes errores de percepción (visión y audición) respecto al sentido y uso de los indicadores habituales; el tránsito, dependiente de circunstancias ajenas al propio objeto de la política de ciencia y tecnología, desde la euforia a la depresión (trastorno bipolar) y las consiguientes pérdidas de sentido de la realidad. De acuerdo con la aproximación metafórica aplicada, se proponen terapias para superar la “crisis” a las que se les aplica la analogía de las nuevas terapias regenerativas, orientadas a la corrección de procesos degenerativos. Entre ellas se incluye la incorporación (trasplante) en la marchita política científica de viejos conceptos como los de “gobernanza” y “espacios” que pueden actuar, de nuevo simbólicamente, como elementos troncales (pluripotentes) para que sirvan como regeneradores de una gestión política habitualmente apoyada en aproximaciones burocráticas y académicas esencialmente simples y tradicionales.
Targeting connexin 43 in diabetic wound healing
Authors: Bajpai S , Shukla VK , Tripathi K , Srikrishna S , Singh RK
Published: June 2009

The unknown mechanisms of impaired tissue repair in diabetes mellitus are making this disease a serious clinical problem for the physicians worldwide. The lacuna in the knowledge of the etiology of diabetic wounds necessitates more focused research in order to develop new targeting tools with higher efficacy for their effective management. Gap-junction proteins, connexins, have shown some promising results in the process of diabetic wound healing. Till now the role of connexins has been implicated in peripheral neuropathy, deafness, skin disorders, cataract, germ cell development and treatment of cancer. Recent findings have revealed that gap junctions play a key role in normal as well as diabetic wound healing. The purpose of this review is to provide the information related to etiology, epidemiology, clinical presentation of diabetic wounds and to analyze the role of connexin 43 (Cx43) in the diabetic wound healing process. The current control strategies and the future research challenges have also been discussed briefly in this review.
Risk factors for diabetic retinopathy in self-reported rural population with diabetes
Authors: Rani PK , Raman R , Chandrakantan A , Pal SS , Perumal GM , Sharma T
Published: June 2009

Background:

Diabetes and its related microvascular complications like diabetic retinopathy (DR) are showing increased prevalence in India. However, the magnitude of DR in rural population with diabetes needs exploration.

Aim:

To estimate the prevalence and risk factors for the presence and severity of diabetic retinopathy in the self-reported rural population with diabetes.

Settings and Design:

In a cross-sectional study, a total of 26,519 participants (age ≥ 30 years) attended 198 diabetic retinopathy screening camps conducted in three southern districts of Tamilnadu, India, between February 2004 and April 2006.

Materials and Methods:

All the participants underwent a dilated eye examination to detect DR by indirect ophthalmoscopy. Systemic and ocular risk factor estimation was done in a comprehensive examination.

Statistical Analysis:

Univariate and stepwise regression analyses were done to identify the independent risk factors associated with the presence and severity of retinopathy. Results: The prevalence of diabetic retinopathy was 17.6% among the self-reported rural population with diabetes. The prevalence of referable (sight threatening) retinopathy was 5.3%. Risk factors associated with the development of any DR were male gender (OR= 1.37), longer duration of diabetes (per year, OR= 1.07), lean body mass index (OR= 1.30), higher systolic blood pressure (per 10 mm Hg, OR= 1.18), and insulin treatment (OR= 1.34; P < 0.0001). Risk factors associated with referable retinopathy included longer duration of diabetes (per year, OR= 1.22), lean body mass index (OR= 1.25), higher systolic blood pressure (per 10 mm Hg, OR= 1.03), and insulin treatment (OR= 1.36; P < 0.0001).

Conclusion:

The study identified risk factors associated with DR in the rural population with diabetes. The results suggested that there was a need for formulating effective preventive strategies to minimize avoidable blindness due to diabetes, in rural areas.
Clinical information in drug package inserts in India
Authors: Shivkar YM
Published: June 2009

Background:

It is widely recognized that accurate and reliable product information is essential for the safe and effective use of medications. Pharmaceutical companies are the primary source of most drug information, including package inserts. Package inserts are printed leaflets accompanying marketed drug products and contain information approved by the regulatory agencies. Studies on package inserts in India, in 1996, had shown that crucial information was often missing and they lacked uniformity.

Aim:

To assess the presentation and completeness of clinically important information provided in the currently available package inserts in India.

Materials and Methods:

Package inserts accompanying allopathic drug products marketed by pharmaceutical companies in India were collected. These package inserts were analyzed for the content of clinically important information in various sections.

Statistical Analysis:

The results were expressed as absolute numbers and percentages. Results: Preliminary analyses revealed that most package inserts did contain information under headings, such as, therapeutic indications, contraindications, undesirable effects, etc., listed in the Drugs and Cosmetics Rules 1945. The findings indicated considerable improvement in package inserts since 1996. However, on critical evaluation it was revealed that clinically important information was not well presented and was often incomplete. Information with regard to pediatric and geriatric use was present in only 44% and 13% of the package inserts, respectively. Only five of the inserts had information on the most frequent adverse drug reactions associated with the drug. Also, information on interactions and overdosage was often missing.

Conclusion:

Although the package inserts appear to have improved over the past decade there is still a definite need to further refine the clinical information contained, to minimize the risks to patients. This could be brought about by self-regulation on the part of the industry as well as by updating the relevant guidelines in line with those of developed countries.
Spontaneous closure of a traumatic intrarenal pseudoaneurysm
Authors: Madhusudhan KS , Sharma S , Seth A
Published: June 2009

Renal artery pseudoaneurysms caused by blunt abdominal trauma are uncommon. It requires treatment with angioembolization because of high risk of rupture. Spontaneous closure of the pseudoaneurysm is extremely unusual. We report a case of a 29-year-old male who developed a traumatic intrarenal pseudoaneurysm that later resolved spontaneously. This report provides an insight into the natural history of renal pseudoaneurysm and suggests a potential option of managing them conservatively.
Medical education in Maharashtra
Authors: Hira RS , Gupta AK , Salvi VS , Ross MW
Published: June 2009

Background:

There is hardly any structured study reporting the perspective of medical students, with regard to the medical education system in Maharashtra, which is facing challenges.

Aim:

A perception study of students was conducted to explore the situation, challenges, and consequent solutions of medical education in Maharashtra.

Settings and Design:

A descriptive perception study.

Materials and Methods:

A structured questionnaire was e-mailed to 92 students, and interviews with seven key-informants comprising of faculty, administrators, and policy makers were conducted, to gather qualitative insights. Results: Thirty-seven student replies were received and analyzed. The satisfaction level of student respondents for various factors was as follows: infrastructure 18/37 (48.6%), quality of teaching 14/37 (37.8%), patient population 22/37 (59.5%), and administration 8/37 (21.6%). Ninety-two percent (34/37) of the students stated that the fundamental problem was the inability of the system to attract good, quality teachers. The reasons stated were low salaries, low level of job satisfaction, high level of bureaucracy, and high work load.

Conclusions:

The medical education system in Maharashtra is viewed as being stagnant. The respondents emphasized an urgent need for educational reforms, which should include better compensation for teachers, sharing of facilities between government and private medical colleges, and improved efficiency of the Medical Council of India. In the long run a public-private mix with sharing of resources may be a plausible solution.
Declaration of Helsinki, 2008
Authors: Puri KS , Suresh KR , Gogtay NJ , Thatte UM
Published: June 2009

The Declaration of Helsinki (DoH) was adopted by the World Medical Association (WMA) in 1964, as a statement of ethical principles, to provide guidance to physicians and other participants in medical research involving human subjects. Having undergone several amendments, the most recent version was approved on 18 October 2008, by the WMA General Assembly at Seoul, South Korea, replacing all previous versions. This version highlights issues such as, participant safety, the need to include participants from otherwise underrepresented groups, clinical trial registration, post-study access, usage of data and human tissues, compensating participants with research-related injury, and usage of placebo.

In this article, we discuss the major aspects of the 2008 version, including the impact of this version on all stakeholders in research, including, investigators, ethics committee members, sponsors, authors, editors, and reviewers.
Azathioprine induced pancytopenia
Authors: Hadda V , Pandey BD , Gupta R , Goel A
Published: June 2009

Azathioprine is commonly used for treatment of lupus nephritis. Myelosuppression is known to occur with azathioprine, but severe pancytopenia is uncommon. A 23-year-old man with lupus nephritis was initially treated with intravenous cyclophosphamide pulses and oral prednisolone along with enalapril and frusemide. Following six months of cyclophosphamide, he was initiated on oral azathioprine as maintenance therapy. He subsequently returned with febrile neutropenia and severe bone marrow suppression. Fever responded to broad spectrum antibiotics and his counts gradually improved following granulocyte-macrophage colony stimulating factor. When last seen in October, he was symptom free and disease activity in control. We suggest that physicians remain sensitive to possibility of azathioprine induced severe bone marrow suppression. Frequent monitoring of blood counts is probably the best way to avoid this complication specially, where testing for thiopurine methyltransferase is not available.
Montelukast induced acute hepatocellular liver injury
Authors: Harugeri A , Parthasarathi G , Sharma J , D′Souza GA , Ramesh M
Published: June 2009

A 46-year-old male with uncontrolled asthma on inhaled albuterol and formoterol with budesonide was commenced on montelukast. He developed abdominal pain and jaundice 48 days after initiating montelukast therapy. His liver tests showed an increase in serum total bilirubin, conjugated bilirubin, aspartate aminotranferase, alanine aminotranferase, and alkaline phosphatase. The patient was evaluated for possible non-drug related liver injury. Montelukast was discontinued suspecting montelukast induced hepatocellular liver injury. Liver tests began to improve and returned to normal 55 days after drug cessation. Causality of this adverse drug reaction by the Council for International Organizations of Medical Sciences or Roussel Uclaf Causality Assessment Method (CIOMS or RUCAM) and Naranjo's algorithm was 'probable'. Liver tests should be monitored in patients receiving montelukast and any early signs of liver injury should be investigated with a high index of suspicion for drug induced liver injury.
Efficient Light‐Emitting Devices Based on Phosphorescent Polyhedral Oligomeric Silsesquioxane Materials
Authors: Yang Xiaohui , Froehlich Jesse D. , Chae Hyun Sik , Li Sheng , Mochizuki Amane , Jabbour Ghassan E.
Published: June 2009

Synthesis, photophysical, and electrochemical characterizations of iridium‐complex anchored polyhedral oligomeric silsesquioxane (POSS) macromolecules are reported. Monochromatic organic light‐emitting devices based on these phosphorescent POSS materials show peak external quantum efficiencies in the range of 5–9%, which can be driven at a voltage less than 10 V for a luminance of 1000 cd m−2. The white‐emitting devices with POSS emitters show an external quantum efficiency of 8%, a power efficiency of 8.1 lm W−1, and Commission International de'lÉclairage coordinates of (0.36, 0.39) at 1000 cd m−2. Encouraging efficiency is achieved in the devices based on hole‐transporting and Ir‐complex moieties dual‐functionalized POSS materials without using host materials, demonstrating that triplet‐dye and carrier‐transporting moieties functionalized POSS material is a viable approach for the development of solution‐processable electrophosphorescent devices.
PbS and CdS Quantum Dot‐Sensitized Solid‐State Solar Cells: “Old Concepts, New Results”
Authors: Lee HyoJoong , Leventis Henry C. , Moon Soo‐Jin , Chen Peter , Ito Seigo , Haque Saif A. , Torres Tomas , Nüesch Frank , Geiger Thomas , Zakeeruddin Shaik M. , Grätzel Michael , Nazeeruddin Md. Khaja
Published: June 2009

Lead sulfide (PbS) and cadmium sulfide (CdS) quantum dots (QDs) are prepared over mesoporous TiO2 films by a successive ionic layer adsorption and reaction (SILAR) process. These QDs are exploited as a sensitizer in solid‐state solar cells with 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) as a hole conductor. High‐resolution transmission electron microscopy (TEM) images reveal that PbS QDs of around 3 nm in size are distributed homogeneously over the TiO2 surface and are well separated from each other if prepared under common SILAR deposition conditions. The pore size of the TiO2 films and the deposition medium are found to be very critical in determining the overall performance of the solid‐state QD cells. By incorporating promising inorganic QDs (PbS) and an organic hole conductor spiro‐OMeTAD into the solid‐state cells, it is possible to attain an efficiency of over 1% for PbS‐sensitized solid‐state cells after some optimizations. The optimized deposition cycle of the SILAR process for PbS QDs has also been confirmed by transient spectroscopic studies on the hole generation of spiro‐OMeTAD. In addition, it is established that the PbS QD layer plays a role in mediating the interfacial recombination between the spiro‐OMeTAD+ cation and the TiO2 conduction band electron, and that the lifetime of these species can change by around 2 orders of magnitude by varying the number of SILAR cycles used. When a near infrared (NIR)‐absorbing zinc carboxyphthalocyanine dye (TT1) is added on top of the PbS‐sensitized electrode to obtain a panchromatic response, two signals from each component are observed, which results in an improved efficiency. In particular, when a CdS‐sensitized electrode is first prepared, and then co‐sensitized with a squarine dye (SQ1), the resulting color change is clearly an addition of each component and the overall efficiencies are also added in a more synergistic way than those in PbS/TT1‐modified cells because of favorable charge‐transfer energetics.
Synthesis and Structure–Property Relations of a Series of Photochromic Molecular Glasses for Controlled and Efficient Formation of Surface Relief Nanostructures
Authors: Walker Roland , Audorff Hubert , Kador Lothar , Schmidt Hans‐Werner
Published: June 2009

This paper reports on the synthesis and properties of a new series of photochromic molecular glasses and their structure–property relations with respect to a controlled and efficient formation of surface relief nanostructures. The aim of the paper is to establish a correlation between molecular structure, optical susceptibility, and the achievable surface relief heights. The molecular glasses consist of a triphenylamine core and three azobenzene side groups attached via an ester linkage. Structural variations are performed with respect to the substitution at the azobenzene moiety in order to promote a formation of a stable amorphous phase and to tune absorption properties and molecular dynamics. Surface relief gratings (SRGs) and complex surface patterns can easily be inscribed via holographic techniques. The modulation heights are determined with an equation adapted from the theory for thin gratings, and the values are confirmed with AFM measurements. Temperature‐dependent holographic measurements allow for monitoring of SRG build‐up and decay and the stability at elevated temperatures, as well as determination of the glass transition temperature. SRG modulation heights of above 600 nm are achieved. These are the highest values reported for molecular glasses to date. The surface patterns of the molecular glasses are stable enough to be copied in a replica molding process. It is demonstrated that the replica can be used to transfer the surface pattern onto a common thermoplastic polymer.
Influence of Dielectric Surface Chemistry on the Microstructure and Carrier Mobility of an n‐Type Organic Semiconductor
Authors: Dhagat Parul , Haverinen Hanna M. , Kline R. Joseph , Jung Youngsuk , Fischer Daniel A. , DeLongchamp Dean M. , Jabbour Ghassan E.
Published: June 2009

This paper examines the microstructure evolution of 3,4,9,10‐perylene‐tetracarboxylic bis‐benzimidazole (PTCBI) thin films resulting from conditions imposed during film deposition. Modification of the silicon dioxide interface with a hydrophobic monolayer (octadecyltrichlorosilane (OTS‐18)) alters the PTCBI growth habit by changing the unit cell contact plane. PTCBI films deposited on oxide surface have an orientation of (011), while films atop OTS‐treated oxide surface have a preferred orientation of (001). The quality of the self assembled monolayer does not appear to influence the PTCBI growth preference significantly yet it enhances the carrier mobility, suggesting that charge traps are adequately passivated due to uniform monolayer coverage. High‐quality monolayers result in n‐type carrier mobility values of 0.05 cm2V–1s–1 Increasing the substrate temperature during PTCBI film deposition correlates with an increase in mobility that is most significant for films deposited on OTS‐treated surface.
Improving the Hydrogen Reaction Kinetics of Complex Hydrides
Authors: Yang Jun , Hirano Shinichi
Published: June 2009

Alanates, borohydrides, and amides are complex hydrides with high concentration hydrogen that have been actively investigated for materials‐based hydrogen storage on‐board polymer electrolyte membrane fuel cell (PEMFC) vehicle applications. The major challenge is to release hydrogen at fuel cell working temperature range at fast enough rate without simultaneous desorption of fuel cell poisoning impurities. We review recent progress in hydrogen reaction mechanism and schemes for complex hydride hydrogen storage.
Controlled Growth Factor Delivery for Tissue Engineering
Authors: Tayalia Prakriti , Mooney David J.
Published: June 2009

Growth factors play a crucial role in information transfer between cells and their microenvironment in tissue engineering and regeneration. They initiate their action by binding to specific receptors on the surface of target cells and the chemical identity, concentration, duration, and context of these growth factors contain information that dictates cell fate. Hence, the importance of exogenous delivery of these molecules in tissue engineering is unsurprising, considering their importance for tissue regeneration. However, the short half‐lives of growth factors, their relatively large size, slow tissue penetration, and their potential toxicity at high systemic levels, suggest that conventional routes of administration are unlikely to be effective. In this review, we provide an overview of the design criteria for growth factor delivery vehicles with respect to the growth factor itself and the microenvironment for delivery. We discuss various methodologies that could be adopted to achieve this localized delivery, and strategies using polymers as delivery vehicles in particular.
Advanced Material Strategies for Tissue Engineering Scaffolds
Authors: Freed Lisa E. , Engelmayr George C. , Borenstein Jeffrey T. , Moutos Franklin T. , Guilak Farshid
Published: June 2009

Tissue engineering seeks to restore the function of diseased or damaged tissues through the use of cells and biomaterial scaffolds. It is now apparent that the next generation of functional tissue replacements will require advanced material strategies to achieve many of the important requirements for long‐term success. Here, we provide representative examples of engineered skeletal and myocardial tissue constructs in which scaffolds were explicitly designed to match native tissue mechanical properties as well as to promote cell alignment. We discuss recent progress in microfluidic devices that can potentially serve as tissue engineering scaffolds, since mass transport via microvascular‐like structures will be essential in the development of tissue engineered constructs on the length scale of native tissues. Given the rapid evolution of the field of tissue engineering, it is important to consider the use of advanced materials in light of the emerging role of genetics, growth factors, bioreactors, and other technologies.
Theoretical studies on structural and electrical properties of PES/SPEEK blend nanofiltration membrane
Authors: Ismail A. F. , Lau W. J.
Published: June 2009

Polyethersulfone (PES) nanofiltration membranes were prepared using a simple dry‐jet wet spinning technique with different contents of sulfonated poly(ether ether ketone) (SPEEK) ranging from 0 to 4 wt %. The structural parameters (rp and Ak/Δx) and electrostatic properties (ξ and X) of the blend membranes were deduced by employing the combination of irreversible thermodynamic model, steric hindrance pore (SHP) model, and Teorell‐Meyer‐Sievers (TMS) model. The modeling results obtained have been analyzed and discussed. The mean pore radius and pore size distribution of the blends were also determined based on the theoretical models. The results showed that pore radius increased with increasing the concentration of SPEEK from 0 to 2 wt % but decreased with a further increase in SPEEK content. The water flux, however, showed a systematically increase with increasing SPEEK content. The SPEEK also showed significant effect on membrane electrical properties. Both effective charge density and ratio of effective charge density to electrolyte solution increased with increasing concentration of SPEEK in the dope solution, reaching a value of −21.02 and −2.29, respectively. The pore radius which was determined by using different transport models has also been analyzed and discussed. It is found that the addition of SPEEK into dope solution is one of the paramount parameters in developing the negatively charged nanofiltration membrane with enhanced water flux while retaining the pore radius in the nanometer range. © 2009 American Institute of Chemical Engineers AIChE J, 2009
A phase II study of 5‐day intravenous azacitidine in patients with myelodysplastic syndromes
Authors: Martin Mike G. , Walgren Richard A. , Procknow Elizabeth , Uy Geoffrey L. , Stockerl‐Goldstein Keith , Cashen Amanda F. , Westervelt Peter , Abboud Camille N. , Kreisel Frederieke , Augustin Kristan , DiPersio John F. , Vij Ravi
Published: June 2009

The approved 7‐day schedule of subcutaneous azacitidine for myelodysplastic syndrome is associated with injection site reactions and bruising and may be inconvenient because of the need for weekend doses. Although pharmacokinetic data with IV azacitidine suggests equivalence, there are no efficacy data published. Patients with all myelodysplastic syndromes (MDS) FAB subtypes were enrolled and received 75 mg/m2/d of azacitidine by 20‐min intravenous infusion for 5 days in every 28 days. Global methylation studies were performed at baseline and prior to Cycle 3. Twenty‐five patients were enrolled and 22 were evaluable. Median age was 69.5 years; 9 (41%) patients had lower‐risk disease (IPSS Low or Int‐1) and 13 (59%) had higher‐risk disease (IPSS Int‐2 or High). Twenty‐seven percent of patients responded (5 CRs and 1 PR). The median time to response was 108 days. The median PFS was 339 days (11.3 months), the median OS was 444 days (14.8 months) and the median duration of response (DOR) was 450 days (15.0 months). Global methylation studies suggest a greater degree of demethylation in responders. This regimen appeared to offer a PR + CR rate and median DOR somewhat similar to what has been reported with the 7‐day subcutaneous regimen; however, OS was shorter. Am. J. Hematol. 2009. © 2009 Wiley‐Liss, Inc.
Association analyses between brain‐expressed fatty‐acid binding protein (FABP) genes and schizophrenia and bipolar disorder
Authors: Iwayama Yoshimi , Hattori Eiji , Maekawa Motoko , Yamada Kazuo , Toyota Tomoko , Ohnishi Tetsuo , Iwata Yasuhide , Tsuchiya Kenji J. , Sugihara Genichi , Kikuchi Mitsuru , Hashimoto Kenji , Iyo Masaomi , Inada Toshiya , Kunugi Hiroshi , Ozaki Norio , Iwata Nakao , Nanko Shinichiro , Iwamoto Kazuya , Okazaki Yuji , Kato Tadafumi , Yoshikawa Takeo
Published: June 2009

Deficits in prepulse inhibition (PPI) are a biological marker for psychiatric illnesses such as schizophrenia and bipolar disorder. To unravel PPI‐controlling mechanisms, we previously performed quantitative trait loci (QTL) analysis in mice, and identified Fabp7, that encodes a brain‐type fatty acid binding protein (Fabp), as a causative gene. In that study, human FABP7 showed genetic association with schizophrenia. FABPs constitute a gene family, of which members FABP5 and FABP3 are also expressed in the brain. These FABP proteins are molecular chaperons for polyunsaturated fatty acids (PUFAs) such as arachidonic and docosahexaenoic acids. Additionally, the involvement of PUFAs has been documented in the pathophysiology of schizophrenia and mood disorders. Therefore in this study, we examined the genetic roles of FABP5 and 3 in schizophrenia (N = 1,900 in combination with controls) and FABP7, 5, and 3 in bipolar disorder (N = 1,762 in the case–control set). Three single nucleotide polymorphisms (SNPs) from FABP7 showed nominal association with bipolar disorder, and haplotypes of the same gene showed empirical associations with bipolar disorder even after correction of multiple testing. We could not perform association studies on FABP5, due to the lack of informative SNPs. FABP3 displayed no association with either disease. Each FABP is relatively small and it is assumed that there are multiple regulatory elements that control gene expression. Therefore, future identification of unknown regulatory elements will be necessary to make a more detailed analysis of their genetic contribution to mental illnesses. © 2009 Wiley‐Liss, Inc.
Mono‐, bis‐ and tris‐piperidine fused imidazolinium salts: their in situ catalytic applications for CC bond formation in aqueous solutions
Authors: Türkmen Hayati , Can Rahime , Çetinkaya Bekir
Published: June 2009

The 1,5,6,7,8,8a‐hexahydroimidazo[1,5‐a]pyridine, 3, was quaternized with 2‐(bromomethyl‐1,3,5‐trimethylbenzene, 1,4‐bis(bromomethyl)‐2,3,5,6‐tetramethylbenzene, 2,4‐bis(bromomethyl)‐1,3,5‐trimethylbenzene, 1,3,5‐tris(bromomethyl)‐2,4,6‐trimethylbenzene and 1,3,5‐tris(bromomethyl)‐2,4,6‐triethylbenzene to obtain mono‐, bis‐ and tris‐imidazolinium salts (4–7) which were characterized by elemental analysis and NMR spectroscopy. In order to understand the effects of these changes on the N‐substituent and how they translate to catalytic activity, these new salts (4–7) with Pd(OAc)2 were applied as in situ catalysts for Suzuki‐Miyaura and Heck‐Mirozoki cross‐coupling reactions of aryl chlorides and aryl bromides, respectively. The tris‐imidazolinium salts (7) were found to be more efficient than the related analogs 4–6. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and properties of cardanol‐based epoxidized novolac resins modified with carboxyl‐terminated butadiene–acrylonitrile copolymer
Authors: Yadav Ranjana , Srivastava Deepak
Published: June 2009

Cardanol‐based, novolac‐type phenolic resins were synthesized with a cardanol‐to‐formaldehyde molar ratio of 1 : 0.7 with different dicarboxylic acid catalysts, including oxalic and succinic acids. These novolac resins were epoxidized with a molar excess of epichlorohydrin at 120°C in a basic medium. The epoxidized novolac resins were separately blended with different weight ratios of carboxyl‐terminated butadiene–acrylonitrile copolymer (CTBN) ranging between 0 and 20 wt % with an interval of 5 wt %. All of the blends were cured at 120°C with a stoichiometric amount of polyamine. The formation of various products during the synthesis of the cardanol‐based novolac resin and epoxidized novolac resin and the blending of the epoxidized novolac resin with CTBN was studied by Fourier transform infrared spectroscopy analysis. Furthermore, the products were also confirmed by proton nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy analysis. The molecular weights of the prepared novolacs and their epoxidized novolac resins were determined by gel permeation chromatography analysis. The blend samples, in both cases, with 15 wt % CTBN concentrations showed the minimum cure times. These blend samples were also the most thermally stable systems. The blend morphology, studied by scanning electron microscopy analysis, was, finally, correlated with the structural and property changes in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The effect of CTBN concentrations on the kinetic parameters of decomposition of blends of cardanol‐based epoxidized novolac resin modified with carboxyl‐terminated liquid copolymer
Authors: Yadav Ranjana , Srivastava Deepak
Published: June 2009

Cardanol‐based novolac resins were separately prepared with different mole ratios of cardanol‐to‐formaldehyde with different acid catalysts. These resins were epoxidized with epichlorohydrin, in basic medium, at 120°C. The resins were, separately, blended with different weight percentages of carboxyl‐terminated butadiene acrylonotrile copolymer and cured with polyamine. Structural changes during blending were studied by FTIR spectroscopic analysis. Coats–Redfern equation was utilized to calculate the kinetic parameters, viz., order of decomposition reaction (n), activation energy (E), pre‐exponential factor (Z), and rate decomposition constant (k), for the decomposition of the samples. It was found that the degradation of the epoxies and their blend samples proceeded in two steps. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Microstructure and rheologic development of polypropylene/nano‐CaCO3 composites along twin‐screw extruder
Authors: Jiang Guo , Huang Han‐Xiong
Published: June 2009

Polypropylene/nano‐calcium carbonate (PP/nano‐CaCO3) composites were prepared by using an intermeshing, co‐rotating twin‐screw extruder. Two different screw configurations, denoted by screws A and B, respectively, were employed. The former provided high dispersive mixing and the later provided high dispersive and distributive mixing. Effect of mixing type on microstructure and rheologic development of nanocomposites was investigated by taking samples from four locations along screws A and B. Transmission electron microscopy results show that in the sample at the exit of extruder, the percentage of nano‐CaCO3 particles with the equivalent diameter lower than 100 nm along screws A and B is 66.5 and 79.0%. respectively. Moreover, for screw B, the number‐averaged diameter at four sampling locations is smaller than that for screw A. This means that the distributive mixing, provided by screw B, favors the size decrease of nano‐CaCO3 in the PP matrix. In addition, rheologic results show that the decrease of complex viscosity for the nanocomposites is deeply related to turbine mixing elements, which provides distributive mixing. The online melt shear viscosity of the nanocomposite at the exit of extruder prepared by screw B is lower than that of pure PP. This is related to the dispersion of nano‐CaCO3 in PP matrix. Finally, the relationship between rheologic properties and microstructure was analyzed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of clay contents on the dynamic mechanical and rheological properties of polypropylene/MAH‐g‐POE/clay composites
Authors: Qiao Xiuying , Zhong Weixia , Sun Kang , Chen Xiaodong
Published: June 2009

A series of polypropylene/maleic anhydride grafted polypropylene octane elastomer (MAH‐g‐POE)/clay (PPMC) nanocomposites were prepared with a novel compatilizer MAH‐g‐POE and different contents of octadecyl amine modified montmorillonite, and the effects of clay contents on the dynamic mechanical and rheological properties of these PPMC composites were investigated. With clay content increasing, the characteristic X‐ray diffraction peak changed from one to two with intensity decreasing, indicating the decreasing concentration of the intercalated clay layers. The gradual decrease of crystallization temperature of PPMC composites with the increase of clay loading should be attributed to the preferred intercalation of MAH‐g‐POE molecules into clay interlayer during blending, which is also reflected by scanning electron microscopy observations. By evaluating the activation energy for the glass transition process of MAH‐g‐POE and polypropylene (PP) in the PPMC composites, it is found that clay intercalation could cause the restriction effect on the glass transition of both MAH‐g‐POE and PP, and this restriction effect appears stronger for PP and attained the highest degree at 5 wt % clay loading. The melt elasticity of PP could be improved apparently by the addition of MAH‐g‐POE, and 5 wt % clay loading is enough for further enhancing the elastic proportion of PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Enhanced permittivity by the adhesion of conducting and low‐loss insulating ceramics in polystyrene
Authors: George Sumesh , Sebastian Mailadil Thomas
Published: June 2009

Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ (CLNT)–polystyrene–La0.5Sr0.5CoO3−δ (LSCO) three‐phase composites were prepared by a two‐step mixing and hot‐molding method. The dielectric properties of polystyrene–CLNT composites were in agreement with the theoretical predictions. The dielectric properties of the three‐phase composites were investigated in terms of the volume fraction of LSCO and the frequency. The relative permittivity of the composites increased with LSCO loading. These composites with low processing temperatures showed a maximum relative permittivity of the order of 104. These composites, with a giant permittivity with a broad smearing region, can find application in electrostrictive, decoupling capacitors and embedded passive devices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of a novel silicon‐containing polytriazole resin
Authors: Huang Jianxiang , Wan Liqiang , Zhang Jian , Gao Fei , Tian Jianjun , Huang Farong , Du Lei
Published: June 2009

4,4′‐Diazidomethylbiphenyl (DAMBP) and poly(dimethylsilylene‐ethynylenephenyleneethynylene) (PDMSEPE) were thermally polymerized to form a novel silicon‐containing polytriazole resin (PDMSEPE‐DAMBP) by 1,3‐dipolar cycloaddition. Differential scanning calorimetry, FTIR, and 13C‐NMR were used to characterize the curing behaviors of PDMSEPE‐DAMBP resins. The results indicated that the resins could cure at temperatures as low as 80°C. Dynamic mechanical analysis showed that there was a glass transition at 302°C for the cured PDMSEPE‐DAMBP resin. The carbon fiber (T700) reinforced PDMSEPE‐DAMBP composites exhibited excellent mechanical properties at room temperature and high property retention at 250°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comfort, chemical, mechanical, and structural properties of natural and synthetic leathers used for apparel
Authors: Sudha Thomas Balasingh , Thanikaivelan Palanisamy , Aaron Kavati Phebe , Krishnaraj Kaliappa , Chandrasekaran Bangaru
Published: June 2009

Natural leather is processed from hides and skins of animals. Synthetic leathers are becoming popular as an alternative material owing to limited availability and varying size of natural leathers. There is a need to understand the properties of natural and synthetic leathers to select proper material for an application. In this study, materials used for apparel application such as natural sheep nappa leather and synthetic polyurethane (PU)‐based leather have been chosen and analyzed for comfort, chemical, physical, and structural properties. It was found that natural sheep nappa leather has enhanced water vapor permeability whereas other comfort properties such as softness and drape ability are comparable to synthetic PU leather. Whereas synthetic PU leather dominated most of the physical properties, especially percentage elongation and stitch tear strength, in specific directions on account of polyester knitted base fabric. Chemical properties of natural sheep nappa leather and synthetic PU leather depended on the individual material composition and characteristics. Scanning electron microscopic (SEM) analysis provided convincing evidence for some of the quantified comfort and physical properties. The results of this study would be useful in selection of proper material for apparel application as well as in providing directions for future research in synthetic leather manufacture. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermoplastic‐modified epoxy resins cured with different functionalities amine mixtures: Morphology, thermal behavior, and mechanical properties
Authors: Blanco Miren , López Marta , De Arcaya Patricia Alvarez , Ramos Jose Angel , Kortaberria Galder , Riccardi Carmen Cristina , Mondragon Iñaki
Published: June 2009

Epoxy matrices inherent brittleness and poor crack resistance make necessary some form of toughening. In this work, to improve their fracture toughness and ductility epoxy matrices were modified by changing its architecture and by the addition of a third component. The matrices architecture were modified by stoichiometrically reacting a bifunctional epoxy resin with different functionalities amine mixtures, one of which being a monoamine that plays the role of chain extender. In the modification by the addition of a third component, poly(methyl methacrylate) (PMMA) was selected as modifier. PMMA is initially miscible with epoxy/amine systems but can phase separate during curing. The kinetics and miscibility of these systems were studied previously. At constant curing conditions, materials from completely opaque (phase separated) to transparent (miscible) can be obtained with the increase in monoamine content. In this work, the effects of the modifier content and of the monoamine : diamine ratio in stoichiometric epoxy/amine mixtures on the resultant morphologies as well as on their thermal and mechanical properties was studied.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of the monomer sequential distribution on the mechanical properties and temperature dependence of an ethylene–tetrafluoroethylene copolymer in association with the phase‐transition behavior
Authors: Arai Kiyotaka , Funaki Atsushi , Aida Shigeru , Phongtamrug Suttinun , Tashiro Kohji
Published: June 2009

The temperature dependence of the mechanical properties of a series of ethylene–tetrafluoroethylene copolymers was interpreted reasonably on the basis of experimental information about the crystalline phase transition and the amorphous‐glass transition behaviors. The crystalline phase‐transition temperature, the glass‐transition temperature, and the bulk modulus were found to depend sensitively on the tetrafluoroethylene content. The magnitude of change in the bulk modulus at the crystalline phase‐transition temperature and glass‐transition temperature was also found to depend sensitively on the tetrafluoroethylene content. These experimental data were interpreted from various levels, including the distribution of the sequential ratios of ethylene–ethylene, tetrafluoroethylene–tetrafluoroethylene, and ethylene–tetrafluoroethylene segments in the copolymer chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparative studies of polypropylene nonwoven sputtered with ITO and AZO
Authors: Wei Qufu , Shao Dongfeng , Deng Bingyao , Xu Yang
Published: June 2009

In this study, the polypropylene (PP) spunbonded nonwoven materials were used as substrates for depositing transparent nanostructures on the fiber surfaces. Magnetron sputter coating technique was used to deposit tin‐doped indium oxide (ITO) and aluminum‐doped zinc oxide (AZO) films onto the nonwoven substrates. The structures and properties of the deposited ITO and AZO films were investigated and compared using atomic force microscopy, energy‐dispersive X‐ray (EDX), and electrical and optical tests. The observations by atomic force microscopy revealed the formation of functional nanostructures on the fiber surfaces. EDX analyses confirmed the deposition of ITO and AZO functional films on the PP fibers. It was found that ITO had more compact structures on the fiber surface than AZO under the same sputtering conditions. The transmittance analysis revealed that the nonwoven substrates deposited with nanostructural AZO showed better ultraviolet shielding effect than those coated with ITO in the same thickness. The nonwoven materials coated with ITO had lower electrical resistance than those coated with AZO in the same thickness. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis of a maleic anhydride grafted polypropylene–butadiene copolymer and its application in polypropylene/styrene–butadiene–styrene triblock copolymer/organophilic montmorillonite composites as a compatibilizer
Authors: Cheng Qiaohuan , Lü Zhanxia , Byrne Hugh J.
Published: June 2009

A maleic anhydride grafted propylene–butadiene copolymer (MPPB) was prepared. Fourier transform infrared spectroscopy and 1H‐NMR results indicate that the maleic anhydride molecules reacted with the double bond in the butadiene unit of the propylene–butadiene copolymer (PPB), and the grafting percentage increased with the butadiene content in the initial copolymer. The gel permeation chromatography results show that the introduction of butadiene in the copolymer prevented the degradation of PPB. The MPPB was applied in polypropylene (PP)/styrene‐butadiene‐styrene triblock copolymer (SBS)/organophilic montmorillonite (OMMT) composites as a compatibilizer. In the presence of 10‐phr MPPB, the impact strength of the composite was improved by about 20%. X‐ray diffraction patterns indicated the formation of the β‐phase crystallization of PP in the presence of MPPB, and a significant decrease in the spherulite size was observed. Transmission electron microscopy (TEM) images showed that the OMMT was better dispersed in the matrix upon the inclusion of MPPB. A better distribution of the rubber phase and a rugged fracture surface were observed in the scanning electron microscopy images as the MPPB proportion was increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Contribution of the melting stage to the evolution of the morphology and chemical conversion of immiscible polyamide/polyethylene blends in twin‐screw extruders
Authors: Yquel V. , Machado A. V. , Covas J. A. , Flat J. J.
Published: June 2009

This study investigates the effects of processing conditions (the screw speed, throughput, barrel temperature, and screw configuration) on the chemical conversion and morphology evolution of polyamide/polyolefin blends along a twin‐screw extruder. Polymer samples were collected rapidly at specific barrel locations with a special sampling device for subsequent chemical and morphological characterization. Increasing the screw speed or using more restrictive screw modules at the beginning of the melting zone promoted a faster reaction and better dispersion along the extruder. Increasing the throughput or decreasing the barrel temperature slowed the evolution of the morphology and chemical conversion along the extruder because of the lower melting rate. As soon as melting started, the chemical reaction took place. However, high chemical conversion rates required extensive melting, that is, significant interface generation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of the mechanical and thermal properties and morphological behavior of biodegradable poly(L‐lactide)/poly(ε‐caprolactone) and poly(L‐lactide)/poly(butylene succinate‐co‐L‐lactate) polymeric blends
Authors: Vilay V. , Mariatti M. , Ahmad Zulkifli , Pasomsouk K. , Todo Mitsugu
Published: June 2009

Two series of biodegradable polymer blends were prepared from combinations of poly(L‐lactide) (PLLA) with poly(ϵ‐caprolactone) (PCL) and poly(butylene succinate‐co‐L‐lactate) (PBSL) in proportions of 100/0, 90/10, 80/20, and 70/30 (based on the weight percentage). Their mechanical properties were investigated and related to their morphologies. The thermal properties, Fourier transform infrared spectroscopy, and melt flow index analysis of the binary blends and virgin polymers were then evaluated. The addition of PCL and PBSL to PLLA reduced the tensile strength and Young's modulus, whereas the elongation at break and melt flow index increased. The stress–strain curve showed that the blending of PLLA with ductile PCL and PBSL improved the toughness and increased the thermal stability of the blended polymers. A morphological analysis of the PLLA and the PLLA blends revealed that all the PLLA/PCL and PLLA/PBSL blends were immiscible with the PCL and PBSL phases finely dispersed in the PLLA‐rich phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009