bluuebunny/crossref_metadata_2025 huggingface dataset:
Chaperone Activity of α B-Crystallin Is Responsible for Its Incorrect Assignment as an Autoantigen in Multiple Sclerosis
Authors: Rothbard Jonathan B. , Zhao Xiaoyan , Sharpe Orr , Strohman Michael J. , Kurnellas Michael , Mellins Elizabeth D. , Robinson William H. , Steinman Lawrence
Published: February 2011

For 15 y, α B-crystallin (heat shock protein [Hsp] B5) has been labeled an autoantigen in multiple sclerosis (MS) based on humoral and cellular responses found in humans and animal models. However, there have been several scientific inconsistencies with this assignment, ranging from studies demonstrating small differences in anticrystallin responses between patients and healthy individuals to the inability of crystallin-specific T cells to induce symptoms of experimental allergic encephalomyelitis in animal models. Experiments in this article demonstrate that the putative anti-HspB5 Abs from 23 MS patients cross-react with 7 other members of the human small Hsp family and were equally present in normal plasma. Biolayer interferometry demonstrates that the binding was temperature dependent, and that the calculated Ka increased as the concentration of the sHsp decreased. These two patterns are characteristic of multiple binding sites with varying affinities, the composition of which changes with temperature, supporting the hypothesis that HspB5 bound the Ab and not the reverse. HspB5 also precipitated Ig heavy and L chains from sera from patients with MS. These results establish that small Hsps bind Igs with high affinity and refute much of the serological data used to assign α B-crystallin as an autoantigen.
Cutting Edge: Primary Innate Immune Cells Respond Efficiently to Polymeric Peptidoglycan, but Not to Peptidoglycan Monomers
Authors: Iyer Janaki K. , Coggeshall K. Mark
Published: February 2011

The cell wall of bacteria induces proinflammatory cytokines in monocytes and neutrophils in human blood. The nature of the stimulating component of bacterial cell walls is not well understood. We have previously shown polymeric peptidoglycan (PGN) has this activity, and the cytokine response requires PGN internalization and trafficking to lysosomes. In this study, we demonstrate that peptidoglycan monomers such as muramyl dipeptide and soluble peptidoglycan fail to induce robust cytokine production in immune cells, although they activate the nucleotide-binding oligomerization domain proteins in transfected cell models. We further show that lysosomal extracts from immune cells degrade intact peptidoglycan into simpler products and that the lysosomal digestion products activate the nucleotide-binding oligomerization domain proteins. We conclude that naive innate immune cells recognize PGN in its polymeric form rather than monomers such as muramyl dipeptide and require PGN lysosomal hydrolysis to respond. These findings offer new opportunities in the treatment of sepsis, especially sepsis arising from Gram-positive organisms.
The effect of rehabilitation on quality of life in female breast cancer survivors in Iran
Authors: Poorkiani M , Abbaszadeh A , Hazrati M , Jafari P , Sadeghi M , Mohammadianpanah M
Published: February 2011

Background: The purpose of this study was to compare the quality of life (Qol) of female breast cancer survivors who received rehabilitation intervention beside medical care and survivors who received medical care alone. Materials and Methods: Fifty-seven female breast cancer survivors were assigned to usual medical care (control group) or to usual medical care plus rehabilitation intervention (experimental group). Qol of all patients was assessed before, 1 week and 3 months after intervention. The intervention consisted of physiotherapy, education and individual counseling. The authors used the European Organization for Research and Treatment of Cancer core questionnaire and breast module (EORTC QLQ-C30/BR23) for the assessment of Qol. Results: Patients who received rehabilitation had significantly better Qol. Overall, mean of Qol scores improved gradually in experimental group from before to 1 week and 3 months after intervention. In contrast, minimal change was observed between pre/post and follow-up measures for control group. Conclusion: Rehabilitation after breast cancer treatment has the potential for physical, psychological and overall Qol benefits.
Pesticides and brain cancer linked in orchard farmers of Kashmir
Authors: Bhat Abdul Rashid , Wani Muhammed Afzal , Kirmani A R , Raina T H
Published: February 2011

Background: The atmosphere of valley of Kashmir is ideal for fresh and dry fruit production. Millions of tons of pesticides, insecticides and fungicides (chemicals like chlorpyriphos, mancozeb, captan, dimethoate, phosalone, etc.) are being used by the orchard farmers to spray the plants, fruits and the leaves every year. The increasing trend in the incidence of primary malignant brain tumors in orchard farmers of Kashmir is alarming. Aim: To determine the relationship between the patients of primary malignant brain tumors and their occupation. Materials and Methods: Retrospectively case files along with death certificates of 432 patients of primary malignant brain tumors and 457 controls (non-tumor neurologic diseases), admitted for treatment simultaneously over a period of 4 years from January 2005 to December 2008, to the Department of Neurosurgery, Sher-I-Kashmir Institute of Medical Sciences (SKIMS), Kashmir, were studied. Follow-up and family contact was established. The serum cholinesterase activity was measured by kinetic/DGKC calorimetric method and ethylenediaminetetraacetic acid (EDTA) samples were sent to the laboratory. The results are expressed in U/l which is U/l×1000. The laboratory at SKIMS, Srinagar, and Dr Lal PathLabs at New Delhi used a reference range for serum cholinesterase as 3167-6333 U/l. Results: Analysis revealed that 90.04% (389 out of 432) patients were orchard-farm workers, orchard residents and orchard playing children exposed to the high levels of multiple types of neurotoxic and carcinogenic (chlorpyriphos, dimethoate, mancozeb and captan) chemicals for more than 10-20 years. About 31.9% (124 out of 389) of these from both sexes were younger than 40 years beginning exposure at an early age and had higher (<6334 U/l) serum cholinesterase (SCE) levels. The 9.96% (43 out of 432) patients were not exposed to pesticides. On the other hand, only 119 patients out of 457 controls had recorded history of pesticide exposure and 338 were unrelated to pesticides. Out of 389 patients, 71.7% (279 out of 389) were males and 28.3% (110 out of 389) including 7 members of three families, 6 were females and 1 male. Conclusion: All orchard-related 389 patients had high grade tumors as compared to the non-pesticide tumors. Mortality in pesticide exposed tumors was 12%. Higher levels of SCE were found in 31.9% (124 out of 389) patients and decreased levels in only 45.3% (176 out of 389) orchard-related patients. The significantcase/control odds ratio (OR) of 0.28, hospital control SCE OR of 1.1 and family control SCE OR of 1.5, points the finger of suspicion toward the link between pesticides and brain cancer.
Quality of life as an outcome variable in the management of advanced cancer
Authors: Bisht Manisha , Bist S S , Dhasmana D C , Saini Sunil
Published: February 2011

Background and Objective: Though well recognized in the West, palliative care and quality of life are relatively newer concepts in a developing country like India. The aim of this study was to assess the effect of palliative care on pain and quality of life and to identify the association between the two. Study Design: Observational prospective study. Materials and Methods: Patients with advanced cancer, receiving palliative drug therapy, were recruited from a tertiary care hospital. City of Hope Medical Center Quality of Life Survey and visual analog scale (VAS) were used to assess the quality of life and cancer pain severity, respectively. Results: A total of 100 patients were included in the study. Palliative drug therapy produced a significant reduction in pain scores expressed as mean±SD in VAS [7.13±2.2 vs. 2.62±2.1 (P<0.001) after 1 month in 93 patients; 7.06±2.1 vs. 2.47±2.1 (P<0.001) after 1 month and 2.02±1.9 (P<0.001) after 2 months in 51 patients]. Also, significant improvement in the quality of life scores [919.78±271.3 vs. 1280.65±306.8 (P<0.01) after 1 month in 93 patients; 950.39±238.2 vs. 1336.67±291 (P<0.01) after 1 month and 1405.49±368.3 (P<0.01) after 2 months in 51 patients] was obtained. There was a high correlation between the average change of pain intensity and quality of life scores (r=−0.53, P<0.02). Overall, a reduction in pain resulted in significant improvement in the quality of life (P<0.001). Conclusion: This study emphasizes the role of palliative care and, more importantly, pain management in improving the quality of life of advanced cancer patients.
Scope and limitations of minimal invasive surgery in practice of pediatric surgical oncology
Authors: Bhatnagar Sushmita , Sarin Yogesh Kumar
Published: February 2011

Management of Solid tumors in children needs a comprehensive multimodality protocol based treatment plan. Open surgical removal of the tumors occurring in any of the sites such as abdomen, thorax, chest wall, HFN (head, face, neck), brain and extremities, is the option which has been traditionally practiced even in the present era and in most of the centers. Nevertheless with the advances in science and technology and with ever increasing usage and expertise of laparoscopy in children, it′s application has extended to treatment of solid tumors in children. A review of the scope of such intervention as well as the limitations of minimal invasive surgery in this specialized field of pediatric surgery has been attempted in this article.
On Best Proximity Points in Metric and Banach Spaces
Authors: Espínola Rafa , Fernández-León Aurora
Published: February 2011

In this paper we study the existence and uniqueness of best proximity points of cyclic contractions as well as the convergence of iterates to such proximity points. We take two different approaches, each one leading to different results that complete, if not improve, other similar results in the theory. Results in this paper stand for Banach spaces, geodesic metric spaces and metric spaces. We also include an appendix on CAT(0) spaces where we study the particular behavior of these spaces regarding the problems we are concerned with.
AV-Courant Algebroids and Generalized CR Structures
Authors: Li-Bland David
Published: February 2011

We construct a generalization of Courant algebroids that are classified by the third coho- mology group H3(A , V), where A is a Lie Algebroid, and V is an A-module. We see that both Courant algebroids and structures are examples of them. Finally we introduce generalized CR structures on a manifold, which are a generalization of generalized complex structures, and show that every CR structure and contact structure is an example of a generalized CR structure.
On Higher Moments of Fourier Coefficients of Holomorphic Cusp Forms
Authors: Lü Guangshi
Published: February 2011

Let be the space of holomorphic cusp forms of even integral weight k for the full modular group. Let and be the n-th normalized Fourier coefficients of two holomorphic Hecke eigencuspforms , respectively. In this paper we are able to show the following results about higher moments of Fourier coefficients of holomorphic cusp forms.

(i)For any , we have

(ii)If , then for any , we have

If , then for any , we have

If and , then for any , we have

where P(x) is a polynomial of degree 3.
Survival Interval in Earthquake Entrapments: Research Findings Reinforced During the 2010 Haiti Earthquake Response
Authors: Macintyre Anthony G. , Barbera Joseph A. , Petinaux Bruno P.
Published: February 2011

Earthquakes can result in collapsed structures with the potential to entrap individuals. In some cases, people can survive entrapment for lengthy periods. The search for and rescue of entrapped people is resource intensive and competes with other postdisaster priorities. The decision to end search and rescue activities is often difficult and in some cases protracted. Medical providers participating in response may be consulted about the probability of continued survival in undiscovered trapped individuals. Historically, many espouse a rigid time frame for viability of entrapped living people (eg, 2 days, 4 days, 14 days). The available medical and engineering data and media reports demonstrate a wide variety in survival “time to rescue,” arguing against the acceptance of a single time interval applicable to all incidents. This article presents historical evidence and reports from the 2010 Haiti earthquake. Factors that may contribute to survival after entombment are listed. Finally, a decision process for projecting viability that considers the critical factors in each incident rather than adhering to a single time frame for ceasing search and rescue activities is proposed. (Disaster Med Public Health Preparedness. 2011;5:13–22)
Ovonic Memory Switching in Multimaterial Fibers
Authors: Danto Sylvain , Ruff Zachary , Wang Zheng , Joannopoulos John D. , Fink Yoel
Published: February 2011

We demonstrate the first rewritable memory in thermally drawn fibers. A high tellurium‐content chalcogenide glass, contacted by metallic electrodes internal to the fiber structure, is drawn from a macroscopic preform. An externally applied voltage is utilized to switch between a high resistance (OFF) and a low resistance (ON) state; this in turn allows the fibers to function as a memory device reminiscent of the ovonic switch. The difference between the ON and OFF states is found to be four orders of magnitude. The glass–crystal phase transition is localized to micrometer‐wide filaments, whose position can be optically controlled along the fiber axis. An architecture that enabled the encoding of multiple bits per fiber is described.
Wafer‐Level Self‐Organized Copolymer Templates for Nanolithography with Sub‐50 nm Feature and Spatial Resolutions
Authors: Krishnamoorthy Sivashankar , Manipaddy Krishna Kumar , Yap Fung Ling
Published: February 2011

Robust lithographic templates, with sub‐50 nm feature and spatial resolutions, that exhibit high patterning integrity across a full‐wafer are demonstrated using self‐organized copolymer reverse micelles on 100 mm Si wafers. A variation of less than 5% in the feature size and periodicity of polymeric templates across the entire wafer is achieved simply by controlling the spin‐coating process. Lithographic pattern transfer using these templates yields Si nanopillar arrays spanning the entire wafer surface and exhibiting high uniformity inherited from the original templates. The variation in geometric characteristics of the pillar arrays across the full‐wafer surface is validated to be less than 5% using reflectance spectroscopy. The physical basis of the change in reflectance with respect to sub‐10 nm variations in geometric parameters of pillar arrays is shown by theoretical modelling and simulations. Successful fabrication of highly durable TiO2 masks for nanolithography with sub‐50 nm feature width and spatial resolutions is achieved through highly controlled vapour phase processing of reverse micelle templates. This allows lithographic pattern‐transfer of organic templates with a feature thickness and separation of less than 10 nm, which is otherwise not possible through other approaches reported in literature.
Circular Nanomagnets: Enhanced Nucleation of Vortices in Soft Magnetic Materials Prepared by Silica Nanosphere Lithography (Adv. Funct. Mater. 5/2011)
Authors: Martin N. , Bigall N. C. , Mönch I. , Gemming T. , Eychmüller A. , Mattheis R. , Schäfer R. , Schultz L. , McCord J.
Published: February 2011

Magnetic vortices show promise as data storage structures, however the vortex formation process imposes a lower limit on the element’s size. In this article a technique is presented, which application increases the probability of nucleating of magnetic vortices in sub‐micrometer sized soft magnetic thin film elements. By tailoring the edge geometry of the elements, the symmetry of their magnetic configuration is broken in a manner which favors vortex nucleation. Micromagnetic simulations are presented, which demonstrate this effect in soft‐magnetic disks with beveled edges. The favored edge geometry is realized by applying nanosphere lithography directly on top of a ferromagnetic thin film material. In this process, the film is masked with a self assembled monolayer of SiO2‐nanospheres and subsequently ion‐etched. The resulting magnetic reversal loops show that in both magnetically isolated as well as in closely packed arrays of beveled disks, vortex formation takes place. The technique presented facilitates the vortex formation even in closely packed and small elements. The lowering of the minimum critical diameter for vortex formation enables a significant increase of data storage density in devices based on magnetic vortices.
Ferroelectric Materials: Probing Local and Global Ferroelectric Phase Stability and Polarization Switching in Ordered Macroporous PZT (Adv. Funct. Mater. 5/2011)
Authors: McLachlan Martyn A. , McComb David W. , Ryan Mary P. , Morozovska Anna N. , Eliseev Eugene A. , Payzant E. Andrew , Jesse Stephen , Seal Katyayani , Baddorf Arthur P. , Kalinin Sergei V.
Published: February 2011

We describe the characterization, ferroelectric phase stability and polarization switching in strain‐free assemblies of PbZr0.3Ti0.7O3 (PZT) nanostructures. The 3‐dimensionally ordered macroporous structures present uniquely large areas and volumes of PZT where the microstructure is spatially modulated and the composition is homogeneous. Variable temperature powder X‐ray diffraction (XRD) studies show that the global structure is crystalline and tetragonal at room temperature and undergoes a reversible tetragonal to cubic phase transition on heating/cooling. The measured phase‐transition temperature is 50–60 °C lower than bulk PZT of the same composition. The local ferroelectric properties were assessed using piezoresponse force spectroscopy that reveal an enhanced piezoresponse from the nanostructured films and demonstrate that the switching polarization can be spatially mapped across these structures. An enhanced piezoresponse is observed in the nanostructured films which we attribute to the formation of strain free films, thus for the first time we are able to assess the effects of crystallite‐size independently of internal stress. Corresponding polarization distributions have been calculated for the bulk and nanostructured materials using a direct variational method and Landau‐Ginzburg‐Devonshire (LGD) theory. By correlating local and global characterization techniques we have for the first time unambiguously demonstrated the formation of tetragonal and ferroelectric PZT in large volume nanostructured architectures. With the wide range of materials available that can be formed into such controlled architectures we conclude that this study opens a pathway for the effective studies of nanoscale ferroelectrics in uniquely large volumes.
Nanomaterials: Applications in Cancer Imaging and Therapy
Authors: Barreto José A. , O’Malley William , Kubeil Manja , Graham Bim , Stephan Holger , Spiccia Leone
Published: February 2011

The application of nanomaterials (NMs) in biomedicine is increasing rapidly and offers excellent prospects for the development of new non‐invasive strategies for the diagnosis and treatment of cancer. In this review, we provide a brief description of cancer pathology and the characteristics that are important for tumor‐targeted NM design, followed by an overview of the different types of NMs explored to date, covering synthetic aspects and approaches explored for their application in unimodal and multimodal imaging, diagnosis and therapy. Significant synthetic advances now allow for the preparation of NMs with highly controlled geometry, surface charge, physicochemical properties, and the decoration of their surfaces with polymers and bioactive molecules in order to improve biocompatibility and to achieve active targeting. This is stimulating the development of a diverse range of nanometer‐sized objects that can recognize cancer tissue, enabling visualization of tumors, delivery of anti‐cancer drugs and/or the destruction of tumors by different therapeutic techniques.
Deactivation kinetics of a HZSM‐5 zeolite catalyst treated with alkali for the transformation of bio‐ethanol into hydrocarbons
Authors: Gayubo Ana G. , Alonso Ainhoa , Valle Beatriz , Aguayo Andrés T. , Bilbao Javier
Published: February 2011

The kinetics of deactivation by coke of a HZSM‐5 zeolite catalyst in the transformation of bioethanol into hydrocarbons has been studied. To attenuate deactivation, the following treatments have been carried out: (i) the zeolite has been subjected to a treatment with alkali to reduce the acid strength of the sites and (ii) it has subsequently been agglomerated into a macro and meso‐porous matrix of bentonite and alumina. The experimental study has been conducted in a fixed bed reactor under the following conditions: temperature, between 300 and 400°C; pressure, 1 atm; space‐time, up to 1.53 (g of catalyst) h (g of ethanol)−1; particle size of the catalyst, between 0.3 and 0.6 mm; feed flowrate, 0.16 cm3 min−1 of ethanol+water and 30 cm3 (NC) min−1 of N2; water content in the feed, up to 75 wt %; time on stream, up to 31 h. The expression for deactivation kinetics is dependent on the concentration of hydrocarbons and water in the reaction medium (which attenuates the deactivation) and, together with the kinetics at zero time on stream, allows the calculation of the evolution with time on stream of the yields and distribution of products (ethylene, propylene and butenes, C1‐C3 paraffins, and C4‐C12). By increasing the temperature in the 300–400°C range the role of ethylene on coke deposition is more significant than that of the other hydrocarbons (propylene, butenes and C4‐C12), which contribute to a greater extent to the formation of coke at 300°C. © 2011 American Institute of Chemical Engineers AIChE J, 58: 526–537, 2012.
Sleep problems and psychosocial work environment among Swedish commercial pilots
Authors: Runeson Roma , Lindgren Torsten , Wahlstedt Kurt
Published: February 2011

Background

The aim of this study was to assess relationships between sleeping problems and the psychosocial work situation based on the job‐strain and iso‐strain models among Swedish commercial pilots.

Methods

Three hundred fifty‐four pilots participated (61%), who are in 2008 responded to a questionnaire concerning sleep problems, the psychosocial work situation, personal factors, and flight length.

Results

Low social support was associated with sleep problems for pilots. High demands were associated with sleep problems among captains and long‐haul flights were associated with sleep problems among first officers. Low skill discretion was associated with less sleep problems among first officers.

Conclusions

Psychosocial climate at work such as low social support affects negatively sleep for both captains and for first officers. More research on what creates a best social support for pilots and cabin crew is needed. Adjusting scheduling work crew teams could increase social support at work and contribute to a better sleep quality. Am. J. Ind. Med. 54:545–551, 2011. © 2011 Wiley‐Liss, Inc.
PARK2 copy number aberrations in two children presenting with autism spectrum disorder: Further support of an association and possible evidence for a new microdeletion/microduplication syndrome
Authors: Scheuerle Angela , Wilson Kathleen
Published: February 2011

Microdeletions of PARK2 have been reported previously in seven patients with autism spectrum disorder. There are no reports of PARK2 microduplications in this population. Presented are two patients, one with deletion and the other with duplication, both with autism spectrum disorder, though their syndromic phenotypes vary. The deletion patient is cognitively normal and ectomorphic: the duplication patient is cognitively impaired, underweight and short. Further, the microduplication patient has demonstrated adverse medication reactions to psychotropic medications active in the dopamine metabolic pathway: cyclopentolate, lisdexamfetamine, methylphenidate. These patients support an association between PARK2 mutations and autism spectrum disorder and suggest that duplications may be equally causative. It is hypothesized that the disparate patient phenotypes may represent a deletion/duplication syndrome and that the adverse medication reactions may be a pharmacogenetic phenomenon. © 2011 Wiley‐Liss, Inc.
Application of immunosignatures to the assessment of Alzheimer's disease
Authors: Restrepo Lucas , Stafford Phillip , Magee D. Mitch , Johnston Stephen Albert
Published: February 2011

Objective:

Accurate assessment of Alzheimer's disease (AD), both presymptomatically and at different disease stages, will become increasingly important with the expanding elderly population. There are a number of indications that the immune system is engaged in AD. Here we explore the ability of an antibody‐profiling technology to characterize AD and screen for peptides that may be used for a simple diagnostic test.

Methods:

We developed an array‐based system to profile the antibody repertoire of transgenic mice with cerebral amyloidosis (TG) and elderly individuals with or without AD. The array consists of 10,000 random sequence peptides (20‐mers) capable of detecting antibody binding patterns, allowing the identification of peptides that mimic epitopes targeted by a donor's serum.

Results:

TG mice exhibited a distinct immunoprofile compared to nontransgenic littermates. Further, we show that dementia patients, including autopsy‐confirmed AD subjects, have distinguishable profiles compared to age‐matched nondemented people. Using antibodies to different forms of Aβ peptide and blocking protocols, we demonstrate that most of this signature is not due to the subject's antibodies raised against Aβ.

Interpretation:

We propose that “immunosignaturing” technology may have potential as a diagnostic tool in AD. ANN NEUROL 2011;
In Vivo Incorporation of Multiple Noncanonical Amino Acids into Proteins
Authors: Hoesl Michael G. , Budisa Nediljko
Published: February 2011

Expansion of the standard genetic code enables the design of recombinant proteins with novel and unusual properties. Traditionally, such proteins have contained only a single type of noncanonical amino acid (NCAA) in their amino acid sequence. However, recently reported initial efforts demonstrate that it is possible with suppression‐based methods to translate two chemically distinct NCAAs into a single recombinant protein by combining the suppression of different termination codons and nontriplet coding units (such as quadruplets). The possibility of expanding the code with various NCAAs simultaneously further increases the toolkit for the generation of multifunctionalized proteins.
Vulcanized paper for separation of alcohol aqueous solutions by pervaporation
Authors: Trang Truong Thi Cam , Kobayashi Takaomi
Published: February 2011

Paper membranes made from vulcanized cellulose were used for the pervaporation (PV) of aqueous solutions containing methanol, ethanol, and isopropanol. It was noted that the vulcanized cellulose paper membranes (VCPM) could effectively separate alcohol and water from the mixture solutions. To observe the effect of the separation of alcohol aqueous mixtures, the permeation behavior of water and alcohol was examined by means of the separation factor and the permeation flux. The values of the permeation flux in the ethanol/water mixtures were found to vary from 6.2 kg/m2h to 2.1 kg/m2h, as the concentration of ethanol increased from 8 to 87 wt %, and the separation factor (α) changed from α = 2.6 to 6.6, respectively. This showed that the VCPM enhanced the separation of water and alcohol. The highest value observed for the permeation flux was 11 kg/m2h at 87 wt % of methanol concentration and the separation factor at this condition was 4.1. It was shown also that an efficient separation was obtained in the isopropanol/water mixture with a separation factor of 16.6. The contact angles of alcohol/water droplets on the VCPM were measured as well as the wettability of the membrane. There was a tendency of decrease for the contact angle, as the alcohol concentration decreased. This suggested that the solvent wettability decreased in high alcohol concentrations. It was concluded that a high permeabilitty of water through the VCPM resulted in the separation of alcohols and water in the PV process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effects of spherical silica on the properties of an epoxy resin system
Authors: Jin Hong‐Yun , Yang Yan‐Qing , Xu Liang , Hou Shu‐En
Published: February 2011

The spherical silica powders were prepared by using an oxygen–acetylene flame method. After spheroidization, a scanning electron microscope investigation revealed that the spheroidization efficiency of the powder was nearly 100%, XRD patterns indicated that the raw crystal silica became amorphous silica. In this study, composites of spherical silica and an epoxy resin were prepared with a homogenizer, followed by a stepwise thermal curing process. The thermal stability and thermal degradation behavior of the composites were studied by a thermogravimetric analyzer. Meanwhile, the effects of spherical silica powder on dynamic mechanical, coefficient of thermal expansion, and mechanical properties of epoxy/silica composites were also investigated. The initial decomposition temperature and mechanical properties increased significantly after adding the spherical silica into the composite. The maximum properties of thermal stability and mechanical properties were observed when spherical silica accounted for 30% of the system. The thermal expansion had been significantly reduced by the addition of silica. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of biphenylated cyanate esters: Thermomechanical resin comparisons within two isomeric series
Authors: Reams Josiah T. , Boyles David A.
Published: February 2011

Three isomeric tetraaryl cyanate esters containing biphenyl moieties {bis‐[4‐(4′‐cyanatophenyl)phenyl]propane, 2,2‐bis‐[4‐(3′‐cyanatophenyl)phenyl]propane, and 2,2‐bis‐[4‐(2′‐cyanatophenyl)phenyl]propane} and three isomeric triaryl cyanate esters {2‐(4′‐hydroxyphenyl)‐2‐[4′‐(4‐hydroxyphenyl)phenyl]propane, 2‐(4′‐hydroxyphenyl)‐2‐[4′‐(3‐hydroxyphenyl)phenyl]propane, and 2‐(4′‐hydroxyphenyl)‐2‐[4′‐(2‐hydroxyphenyl)phenyl]propane} were synthesized from their corresponding bisphenols. The structures of the monomers were confirmed with IR and 1H‐NMR spectroscopy. The curing behavior was investigated with differential scanning calorimetry. Cyanate esters were cured thermally in the absence of a catalyst and were characterized by dynamic mechanical analysis. The results were compared to the properties of commercial bisphenol A polycyanurate. Of the three tetraaryl isomers, 2,2‐bis‐[4‐(2′‐cyanatophenyl)phenyl]propane had the highest melting point, and its corresponding resin had the lowest glass‐transition temperature (Tg). The para isomer displayed the highest Tg value of the three novel tetraaryl resins. The triaryl dicyanate isomers were low‐melting solids, with the ortho and meta isomers existing as liquids at room temperature. The Tg value of the para‐triaryl isomer was the highest of the three triaryl isomers and was about the same as that of bisphenol A polycyanurate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Finishing of silk by acrylic acid in the presence of sodium citrate and potassium per sulphate as catalysts under thermal treatment
Authors: Das D. , Mukherjee A. , Bhattacharya P. , Chakrabarty D.
Published: February 2011

Silk fabric was finished using acrylic acid (AA) as the finishing agent in the presence of sodium citrate and potassium per oxodisulphate catalysts separately or in selected combinations employing a pad‐dry‐cure technique. Treatment with 6% AA at 30°C and at pH 7 produced optimum effects; a batching time of 45–60 min at 30°C, followed by drying of the batched fabric at 95°C for 5 min and curing of the dried fabric at 140°C for 5 min produced most balanced improvements in the properties such as wrinkle recovery, extensibility, and moisture regain with retention of more than 80% of original strength. Sodium citrate catalyst allowed esterification of AA with proteineous constituent of silk and potassium per sulfate catalyst allowed radical polymerization of free AA or silk bound AA moieties; the said process ultimately led to some degree of crosslinking of the chain polymers of silk. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Role of the alkyl moiety and counter ions on the thermal stability of chitosan derivatives
Authors: de Britto Douglas , Campana Filho Sergio Paulo , Assis Odilio B. G.
Published: February 2011

The thermal stability of alkyl chitosan derivatives (RChi) andN,N,N‐trimethyl chitosan bearing different counter ions (TMCX) was assessed by means of TG analyses. Multistep TG curves were observed for TMCX regardless of the counter ion. They exhibited lower DTG peak temperatures (TMCCl/238.2°C, TMCBr/224.5°C, TMCI/222.6°C, and TMC‐SO4/237.0°C) as compared to the parent chitosan (306.4°C) while, in contrast, the RChi showed higher DTG temperatures (ButChi/311.7°C, OctChi/327.8°C, and DodecChi/306.3°C). The apparent activation energy values determined by using the isoconversional method revealed that the RChi derivatives have low activation energy (OctChi/111.6 ± 5 kJ/mol), whereas quaternary salts have high activation energy (TMCI/155.5 ± 10 kJ/mol). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of cationic polyurethane and its application to acrylic fabrics
Authors: El‐Sayed A. Atef , Kantouch F. A. , Kantouch A.
Published: February 2011

The cationic aqueous polyurethane (CAPU) coatings were prepared by reacting isophoron diisocyanate with quaternized diethanolamine (DEA) and poly(ethylene glycol) of two different molecular weights (Mn = 600 and 1000 g/mol; CAPU600 and CAPU1000). The quaternization of DEA and the formation of cationic polyurethane were investigated by Fourier transform infrared analysis. The pilling resistance and the antimicrobial property of the coated acrylic fabric were also studied. Obtained results showed that the pilling resistance of the treated fabrics increased with the increase in the concentration of the used CAPU. The acrylic fabrics treated with CAPU1000 shows higher value of pilling resistance, even at lower concentration in comparison with CAPU600. The higher the curing temperature is, the higher the pilling resistance, fabric roughness, and yellowness of the treated acrylic fabrics are. The untreated fabric showed no antimicrobial property, while the treated fabrics with CAPU showed superior antimicrobial properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Improving transfection of human pulmonary epithelial cells by doping LMW‐PEI‐g‐chitosan with β‐estradiol
Authors: Sun Peng , Zhai Xinyun , Luo Yongfeng , Ma Chaonan , Xu Jun , Liu Wenguang
Published: February 2011

PEI‐grafted chitosan (PEI‐CMCS) copolymer was synthesized through EDC‐mediated amidation reaction between carboxymethyl chitosan and low‐molecular‐weight polyethyleneimine (LMW PEI). PEI‐CMCS and CS/DNA complexes were characterized. Compared with pristine chitosan, the PEI‐CMCS exhibited an enhanced ability to condense DNA. Incorporation of LMW PEI to chitosan was found to achieve higher transfection efficiency and much lower cytotoxicity than PEI25K at an optimum weight ratio of 15 in COS‐7 cells. However, PEI‐CMCS was incompetent to transfer refractory pulmonary epithelial cells. It was demonstrated that doping complex medium or treating cells with a steroid hormone—β‐estradiol significantly improved the transfection efficiency of 16HBE and A549 cells. This study suggests that steroid hormone may become an additive for other cationic polymers to facilitate gene transfection in pulmonary cells. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of hydrazine‐modified polyacrylonitrile nanofibers for the extraction of metal ions from aqueous media
Authors: Saeed Khalid , Park Soo‐Young , Oh Tae‐Jin
Published: February 2011

Polyacrylonitrile (PAN) nanofibers (prepared by an electrospinning technique) were chemically modified with hydrazine. The Fourier transform infrared spectrum of the hydrazine‐modified polyacrylonitrile (HM–PAN) showed that the intensity of the nitrile peak (2250 cm−1) of the PAN nanofibers decreased significantly after treatment with hydrazine. New peaks at about 3400–3100 cm−1 (NH stretching vibration) also appeared, which showed that the hydrazine was chemically attached to the PAN nanofibers. HM–PAN had a smooth surface (as confirmed by a scanning electron microscopy) and was a suitable material for the adsorption of metal ions from aqueous solutions. The adsorption capacity of HM–PAN increased as the adsorption time increased and became constant at 114 and 217 mg/g for Cu(II) and Pb(II) ions, respectively, after 24 h. In addition, more than 90% of the adsorbed Cu(II) and Pb(II) ions were recovered in a 1M HNO3 solution after 1 h. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
New method for estimating the extent of curing of thermosetting prepregs
Authors: Sabzevari S. M. , Alavi‐Soltani S. , Minaie B.
Published: February 2011

Here, we propose a new method for estimating the extent of curing of thermosetting prepregs. In the proposed method, the extent of curing is estimated with the curing index (Ci), defined as the ratio of the glass‐transition temperature (Tg) to the ultimate glass‐transition temperature of the material. The advantages of this new method over the conventional degree of conversion (α) for estimating the extent of curing of thermosetting prepregs are discussed in detail. Ci and α of a toughened epoxy prepreg (977‐2 unidirectional) were obtained for a wide range of isothermal curing temperatures with a differential scanning calorimeter. The ultimate heat of reaction varied inconsistently with decreasing curing temperature; this resulted in erratic behavior of α. However, Ci provided a more consistent estimate of the extent of curing because Tg, unlike α, did not need to be modified on the basis of the curing history of the material and was measured directly with the heat‐flow data from differential scanning calorimetry. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation and properties of thermally conductive photosensitive polyimide/boron nitride nanocomposites
Authors: Li Tung‐Lin , Hsu Steve Lien‐Chung
Published: February 2011

A new thermally conductive photoresist was developed. It was based on a dispersion of boron nitride (BN) nanoflakes in a negative‐tone photosensitive polyimide (PSPI) precursor. 3‐Mercaptopropionic acid was used as the surfactant to modify the BN nanoflake surface for the dispersion of BN nanoflakes in the polymer. The thermal conductivity of the composite films increased with increasing BN fraction. The thermal conductivity of the PSPI/BN nanocomposite was up to 0.47 W m−1 K−1 for a mixture containing 30 wt % nanosized BN filler in the polyimide matrix. Patterns with a resolution of 30 μm were obtained from the PSPI/BN nanocomposites. The PSPI/BN nanocomposites had excellent thermal properties. Their glass‐transition temperatures were above 360°C, and the thermal decomposition temperatures were over 460°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Influence of epoxy resin on the properties of maleic anhydride functionalized acrylonitrile–butadiene–styrene copolymer toughened polyamide 6 blends
Authors: Shulin Sun , Zhuo Chen , Lili Sun , Huixuan Zhang
Published: February 2011

Maleic anhydride functionalized acrylonitrile–butadiene–styrene copolymer (ABS‐g‐MA) was used as an impact modifier of polyamide 6 (PA6). Epoxy resin was introduced into PA6/ABS‐g‐MA blends to further improve their properties. Notched Izod impact tests showed that the impact strength of PA6/ABS‐g‐MA could be improved from 253 to 800 J/m with the addition of epoxy resin when the ABS‐g‐MA content was set at 25 wt %. Differential scanning calorimetry results showed that the addition of epoxy resin made the crystallization temperature and melting temperature shift to lower temperatures; this indicated the decrease in the PA6 crystallization ability. Dynamic mechanical analysis testing showed that the addition of epoxy resin induced the glass‐transition temperature of PA6 and the styrene‐co‐acrylonitrile copolymer phase to shift to higher temperatures due to the chemical reactions between PA6, ABS‐g‐MA, and epoxy resin. The scanning electron microscopy results indicated that the ABS‐g‐MA copolymer dispersed into the PA6 matrix uniformly and that the phase morphology of the PA6/ABS‐g‐MA blends did not change with the addition of the epoxy resin. Transmission electron microscopy showed that the epoxy resin did not change the deformation mechanisms of the PA6/ABS‐g‐MA blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
New copolymers with heterocyclic pendant groups obtained from PVC using microwave‐assisted process
Authors: Lamanna Melisa , D'Accorso Norma
Published: February 2011

We report the synthesis of new copolymers from poly(vinyl chloride) (PVC) with 1,2,4‐triazol‐5‐yl‐sulfanyl pendant groups (PVCT) by nucleophilic substitution using microwave energetic sources. By comparing the synthesis of PVCT between microwave and thermal conditions, it was found that the use of microwave‐assisted process led to higher conversion levels than that of the thermal synthesis. Moreover, significant decrease in reaction times was obtained for the microwave assisted synthesis, which avoided secondary reactions. Conversion yields were calculated from elemental analysis and the molecular weighs were analyzed by means of SEC. The molecular structures of the new copolymers were confirmed by FTIR, 13C NMR and 1H NMR spectroscopies. The morphology of the new copolymers was analyzed by SEM. Thermal properties were studied by TGA and DSC techniques. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Thermal‐initiated hydroxyethyl methacrylate functionalization of multiwalled carbon nanotubes
Authors: Curtzwiler Greg , Costanzo Philip J. , Fernando Ray , Danes Jeffrey E. , Vorst Keith
Published: February 2011

Multiwalled‐carbon nanotubes (MWCNTs) were functionalized via thermoinitiated free radical polymerization of 2‐hydroxyethyl methacrylate (HEMA) using benzoyl peroxide. Tip sonication was used during the polymerization reaction to separate agglomerated nanotubes. The functionalization was confirmed by control experiments and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR). Differential scanning calorimetry indicated that the addition of poly(HEMA)‐MWCNTs to a two‐component polyurethane coating will have little effect on the glass transition temperature of the coating. The poly(HEMA)‐functionalized MWCNTs formed large colloidal structures of highly dispersed nanotubes in both the nonsheared and sheared coatings as determined by atomic force microscopy. This study determined a quick and easy method to functionalize MWCNTs for incorporation into a two‐component polyurethane coating. A simple method for producing ordered structures of the MWCNTs via shear observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A novel composite coupled hardness with flexibleness—polylactic acid toughen with thermoplastic polyurethane
Authors: Hong Hua , Wei Jie , Yuan Yuan , Chen Fang‐Ping , Wang Jing , Qu Xue , Liu Chang‐Sheng
Published: February 2011

With the aim to modify the brittleness of polylactic acid (PLA), it was firstly melt blended with thermoplastic polyurethane (TPU) at six different PLA wt % of 100, 90, 80, 70, 60, and 50 compositions. The properties of PLA/TPU composite were characterized by means of electron microscopy, rheological, mechanical and thermal methods. The results showed that the brittle fracture of pure PLA was gradually transformed into ductile fracture with the addition of the TPU elastomer. The notched impact strength of the composite at 10 wt % TPU was over three times higher than that of pure PLA. The composite was found to be a partially miscible system with shifted glass transition temperatures. The molten blend was shear‐thinning fluid and it could be processed by conventional thermoplastic processes such as extrusion and injection molding. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of hyperbranched polyester‐amides and their application as crosslinkers for polyurethane curing systems
Authors: Lin Dong , Liu Bing , Xu Lei , Budzinski Kristi L. , Shou Chongqi
Published: February 2011

A series of hyperbranched polyester‐amides (S1, S2, S3) with trimethylolpropane as a core molecule were synthesized using core‐dilution/slow monomer addition strategy. The products were characterized by FTIR, 13C NMR, GPC, TGA, hydroxyl value measurement, and viscosity measurement. The result showed that the hyperbranched polyester‐amides synthesized had narrow molecular weight distribution and high degree of branching (DB). The hyperbranched polyester‐amides synthesized were used as crosslinkers for polyurethane curing systems and the mechanical properties of the polyurethane curing systems were investigated. It was found that the best tensile property and tear strength were obtained when the S2 were used as crosslinkers and the molar ratio of OH and NCO was 1 : 1. It was also found that the polyurethane curing systems had the highest hardness and Tg when the S3 were used as crosslinkers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of nano poly(phenylsilsesquioxane) spheres(nano‐PPSQ) and study of the thermal stability and crystallization behavior of PP/nano‐PPSQ composites
Authors: Wang Xinlong , Li Jin , Wu Lianghu
Published: February 2011

The preparation of nano poly(phenylsilsesquioxane) particles (nano‐PPSQ) and the influence of nano‐PPSQ on the thermal stability and crystallization of polypropylene (PP) were studied. The morphology and thermal stability of PP/nano‐PPSQ composites were characterized by scanning electron microscopy (SEM) and the thermogravimetric analysis (TGA). The SEM result showed that the particles were well dispersed in the PP matrix. The TGA results of the PP/nano‐PPSQ composites indicated that the incorporation of nano‐PPSQ can improve the thermal stability of PP. The crystallization behavior and kinetics of PP/nano‐PPSQ composite were studied by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD revealed that the addition of nano‐PPSQ influences the crystallinity and crystal size of PP. The Avrami, Ozawa, and combined Avrami/Ozawa (Mo method) equations were applied to describe the crystallization kinetics and estimate the kinetic parameters of mathematical models under the nonisothermal crystallization of PP and PP/nano‐PPSQ composites. The results show that nano‐PPSQ influences the crystallization temperature and rate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Recycling of chrome‐tanned leather waste in acrylonitrile butadiene rubber
Authors: El‐Sabbagh Salwa H. , Mohamed Ola A.
Published: February 2011

Chrome‐tanned leather waste generated in huge amount from leather industry causing environmental problem; this leather waste was used as filler in acrylonitrile butadiene rubber before treatment and after treatment with ammonia solution and sodium formate. Different formulations of acrylonitrile butadiene rubber/leather waste (untreated–treated with ammonia solution—treated with sodium formate) composites are prepared. The formed composites exhibit a considerable improvement in some of their properties such as rheometric characteristics especially with composites loaded with treated leather waste. Tensile strength, modulus at 100% elongation, hardness, and Young's modulus were improved for composite loaded with treated leather. Crosslinking density in toluene was increased by the incorporation of leather wastes treated or untreated resulting in decreases in swelling equilibrium. Distinct increase in the ageing coefficient and the thermal stability for composites loaded with both treated and untreated leather. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011