bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hyperdense Internal Carotid Artery Sign: Prevalence and Prognostic Relevance in Stroke Thrombolysis
Authors: Fitzsimmons P. R. , Biswas S. , Hill A. M. , Kumar R. , Cullen C. , White R. P. , Sharma A. K. , Durairaj R.
Published: August 2011

Introduction. The hyperdense internal carotid artery sign (HICAS) has been suggested as a common marker of terminal internal carotid artery (ICA) thrombus associated with poor outcomes following thrombolysis. We aimed to investigate the prevalence and prognostic significance of the HICAS in an unselected cohort of patients receiving intravenous thrombolysis.Methods. Prethrombolysis NCCTs of 120 patients were examined for the presence of the HICAS and hyperdense middle cerebral artery sign (HMCAS). A poor outcome was defined as a discharge Barthel score <15 or inpatient death.Results. A HICAS was present in 3 patients (2.5%). Prethrombolysis neurological deficits were significantly more severe in patients with a HICAS (). HICAS was not significantly associated with a poor outcome (). HMCAS was significantly associated with severe prethrombolysis neurological deficits () and a poor outcome ().Conclusions. This study suggests that the prevalence of the HICAS may be lower than previously reported. The presence of a HICAS was associated with severe prethrombolysis neurological deficits in keeping with terminal ICA occlusion. The role of the HICAS as a prognostic marker in stroke thrombolysis remains unclear.
Disease Extent ≥4 cm Is a Prognostic Marker of Local Recurrence in T1-2 Breast Cancer
Authors: Lindquist D. , Hellberg D. , Tot T.
Published: August 2011

Despite improvements of the therapy for breast cancer, a proportion of the patients still get local recurrence. The status of the surgical margins is the most often used parameter for decision regarding additional treatment. However, a negative margin is not a guarantee that there is not residual cancer left in the breast; additional parameters are needed to better predict the risk of local recurrence. The disease extent was evaluated in the surgical specimen from 313 women after breast-conserving therapy using large-section histology and was correlated to the incidence of local recurrence. A disease extent ≥4 cm was shown to be an independent marker for local recurrence; the cumulative 10-year local relapse rate for the group with a disease extent ≥4 cm was 20.5%, and for the rest 6.7%. We conclude that disease extent ≥4 cm seems to be an important factor when evaluating the risk for local recurrence.
MicroRNAs and Alzheimer′s Disease Mouse Models: Current Insights and Future Research Avenues
Authors: Delay Charlotte , Hébert Sébastien S.
Published: August 2011

Evidence from clinical trials as well as from studies performed in animal models suggest that both amyloid and tau pathologies function in concert with other factors to cause the severe neurodegeneration and dementia in Alzheimer’s disease (AD) patients. Accumulating data in the literature suggest that microRNAs (miRNAs) could be such factors. These conserved, small nonprotein‐coding RNAs are essential for neuronal function and survival and have been implicated in the regulation of key genes involved in genetic and sporadic AD. The study of miRNA changes in AD mouse models provides an appealing approach to address the cause‐consequence relationship between miRNA dysfunction and AD pathology in humans. Mouse models also provide attractive tools to validate miRNA targets in vivo and provide unique platforms to study the role of specific miRNA‐dependent gene pathways in disease. Finally, mouse models may be exploited for miRNA diagnostics in the fight against AD.
Effect of LSVT on Lexical Tone in Speakers with Parkinson's Disease
Authors: Whitehill Tara L. , Kwan Lorinda , Lee Flora P.-H. , Chow Mia M.-N.
Published: August 2011

Lee Silverman Voice Treatment (LSVT) has well-documented treatment efficacy for individuals with hypokinetic dysarthria associated with Parkinson's disease (PD). Positive changes have been noted after treatment not only for vocal loudness but also for many other speech dimensions, including intonation (monotonicity). There have been few studies investigating the effect of LSVT on lexical tone which, like intonation, is controlled by variations in fundamental frequency. This study involved 12 Cantonese speakers with idiopathic PD who were enrolled in a standard LVST treatment protocol. Speech data were collected 3-4 days before treatment and 1 day after treatment. A wide variety of perceptual and acoustic variables were analyzed. The results showed significant improvements in loudness and intonation after treatment, but no significant changes in lexical tone. These results have theoretical implications for the relationship between tone and intonation and for models of the physiological control of fundamental frequency.
Involvement of Physical Parameters in Medium Improvement for Tannase Production by Aspergillus niger FETL FT3 in Submerged Fermentation
Authors: Darah I. , Sumathi G. , Jain K. , Hong Lim Sheh
Published: August 2011

Aspergillus niger FETL FT3, a local extracellular tannase producer strain that was isolated from one of dumping sites of tannin-rich barks of Rhizophora apiculata in Perak, Malaysia. This fungus was cultivated in 250 mL Erlenmeyer flask under submerged fermentation system. Various physical parameters were studied in order to maximize the tannase production. Maximal yield of tannase production, that is, 2.81 U per mL was obtained on the fourth day of cultivation when the submerged fermentation was carried out using liquid Czapek-Dox medium containing (percent; weight per volume) 0.25% NaNO3, 0.1% KH2PO4, 0.05% MgSO4 ·7H2O, 0.05% KCl, and 1.0% tannic acid. The physical parameters used initial medium pH of 6.0, incubation temperature of , agitation speed of 200 rpm and inoculums size of  spores/ ml. This research has showed that physical parameters were influenced the tannase production by the fungus with 156.4 percent increment.
Establishment of a Mesenchymal Stem Cell Bank
Authors: Cooper Khushnuma , Viswanathan Chandra
Published: August 2011

Adult stem cells have generated great amount of interest amongst the scientific community for their potential therapeutic applications for unmet medical needs. We have demonstrated the plasticity of mesenchymal stem cells isolated from the umbilical cord matrix. Their immunological profile makes it even more interesting. We have demonstrated that the umbilical cord is an inexhaustible source of mesenchymal stem cells. Being a very rich source, instead of discarding this tissue, we worked on banking these cells for regenerative medicine application for future use. The present paper gives a detailed account of our experience in the establishment of a mesenchymal stem cell bank at our facility.
Purification and Refolding of Overexpressed Human Basic Fibroblast Growth Factor inEscherichia coli
Authors: Alibolandi Mona , Mirzahoseini Hasan
Published: August 2011

This work describes the integration of expanded bed adsorption (EBA) and adsorptive protein refolding operations used to recover purified and biologically active human basic fibroblast growth factor from inclusion bodies expressed inE. coli. Insoluble overexpressed human basic fibroblast growth factor has been purified on CM Hyper Z matrix by expanded bed adsorption after isolation and solubilization in 8 M urea. The adsorption was made in expanded bed without clarification steps such as centrifugation. Column refolding was done by elimination of urea and elution with NaCl. The human basic fibroblast growth factor was obtained as a highly purified soluble monomer form with similar behavior in circular dichroism and fluorescence spectroscopy as native protein. A total of 92.52% of the available human basic fibroblast growth factor was recovered as biologically active and purified protein using the mentioned purification and refolding process. This resulted in the first procedure describing high-throughput purification and refolding of human basic fibroblast growth factor in one step and is likely to have the greatest benefit for proteins that tend to aggregate when refolded by dilution.
The Smallest Pisot Element in the Field of Formal Power Series Over a Finite Field
Authors: Chandoul A. , Jellali M. , Mkaouar M.
Published: August 2011

Dufresnoy and Pisot characterized the smallest Pisot number of degree n ≥ 3 by giving explicitly its minimal polynomial. In this paper, we translate Dufresnoy and Pisot’s result to the Laurent series case. The aim of this paper is to prove that the minimal polynomial of the smallest Pisot element (SPE) of degree n in the field of formal power series over a finite field is given by P(Y) = Yn–XYn-1–αn where α is the least element of the finite field 픽q\{0} (as a finite total ordered set). We prove that the sequence of SPEs of degree n is decreasing and converges to αX: Finally, we show how to obtain explicit continued fraction expansion of the smallest Pisot element over a finite field.
Trunk Extensor Muscle Fatigue Does Not Affect Postural Control during Upright Static Stance in Young-adults and Middle-aged Adults
Authors: Delgado Giselle , Coghlin Chelsea , Earle Katelyn , Holek Andrea , O'Hare Kate
Published: August 2011

Background. Falls can be extremely detrimental to someone’s daily living, as well as life threatening This is especially true for individuals who have back problems, are sedentary, and have other health disorders. The purpose of this study was to investigate the effect of trunk extensor muscles fatigue on static postural control in young healthy adults compared to middle aged subjects. Methods. University students (n=10), and Middle-aged subjects (n=6; 40+ years of age) stood as immobile as possible on a force plate, with their feet together and eyes closed under two conditions; Fatigue and No fatigue. Fatigue was achieved through repetitive extensions of the trunk until a subjective fatigue level was reached. We measured center of pressure (CoP) displacements in the A/P and M/L planes using a force plate to assess standing balance. Findings. We did not observe any significant interaction between age and fatigue indicating that fatigue affected both age groups similarly. The CoP variability was higher for the middle aged compared to the young adults in both the fatigue and no-fatigue conditions. Interpretation. The results of this study indicate that trunk extensor fatigue does not affect balance differently for young compared to middle-aged subjects. This study also suggests that postural control decreases significantly with increasing age. Our finding that trunk extensor fatigue did not significantly affect the postural control of upright stance contradicts previous studies; this difference may be due to the subject sample in our study.
A Systematic Review of Randomized Controlled Interventions for Parents' Distress in Pediatric Leukemia
Authors: Bougea A. , Darviri C. , Alexopoulos E. C.
Published: August 2011

Objective. This review aims to summarize the existing evidence concerning interventions towards reducing stress in parents with a child with leukemia and their effect in child and family wellbeing.Methods. A systematic review strategy was conducted using MEDLINE covering the period January 1980 to June 2010.Results. Seven randomized controlled trials met the inclusion criteria including in total 1045 parents participants. A variety of cognitive-behavioral interventions problem-solving skills training programs have been used for managing distress in parents and children. Outcome measures are assessed by self-report, observer report, behavioral/psychological, and physiological measures. The most prominent methodological problems were the marked heterogeneity in stress measurement and the relative absence of proper measurement and adjustment of moderating and mediating factors. The largest effect has been obtained by combined cognitive-behavioral interventions with promising but limited evidence for several other psychological interventions.Conclusions. Recommendations for future RCTs are provided, and particular attention to the quality of trial design and reporting is highlighted.
Hair lead levels to evaluate the subclinical impact of lead on growth in Sardinian children (Italy)
Authors: Sanna Emanuele , Vallascas Elisabetta
Published: August 2011

Objectives:

The aim of this study was to determine if there are significant relationships between lead concentrations in children's hair and height, sitting height, and estimated leg length.

Methods:

We analyzed three samples collected at different times: 1998, 2002, 2007. The total sample consisted of 825 children between 11 and 14 years of age living in different municipalities of Sardinia (Italy). Inductively coupled plasma atomic emission spectrometry (1998), inductively coupled plasma atomic absorption spectrometry (2002), and inductively coupled mass spectrometry (2007) were used to measure the lead concentration in hair (PbH). Some AAS measurements were also performed on the 1998 and 2007 samples to check the reliability of the data.

Results:

The mean PbH is much higher in 1998 (5.84 μg/g) than in 2002 (1.49 μg/g) and 2007 (0.78 μg/g). Multivariate regression analysis of the three samples, controlling for age and sex, indicates a subclinical impact of lead on growth that differs according to the mean lead concentration in the hair. In fact, for 1998, the relationships between all three anthropometric variables and logPbH are significantly negative. For 2002, there are significant negative associations between height and estimated leg length and logPbH but not between sitting height and logPbH. For 2007, there are not significant associations between logPbH and anthropometric variables.

Conclusions:

Our results support the use of hair lead levels as a biomarker to assess the impact of subclinical lead on the physical growth of children, especially when the study area presents medium and/or high levels of lead pollution. Am. J. Hum. Biol., 2011. © 2011 Wiley‐Liss, Inc.
SLC9A9 mutations, gene expression, and protein–protein interactions in rat models of attention‐deficit/hyperactivity disorder
Authors: Zhang‐James Yanli , DasBanerjee Tania , Sagvolden Terje , Middleton Frank A. , Faraone Stephen V.
Published: August 2011

SLC9A9 (solute carrier family 9, member 9, also known as Na+/H+ exchanger member (NHE9)) is a membrane protein that regulates the luminal pH of the recycling endosome, an essential organelle for synaptic transmission and plasticity. SLC9A9 has been implicated in human attention deficit hyperactivity disorder (ADHD) and in rat studies of hyperactivity. We examined the SLC9A9 gene sequence and expression profile in prefrontal cortex, dorsal striatum and hippocampus in two genetic rat models of ADHD. We report two mutations in a rat model of inattentive ADHD, the WKY/NCrl rat, which affect the interaction of SLC9A9 with calcineurin homologous protein (CHP). We observed an age‐dependent abnormal expression of SLC9A9 in brains of this inattentive model and in the Spontaneous Hypertensive Rat (SHR) model of ADHD. Our data suggest a novel mechanism whereby SLC9A9 sequence variants and abnormalities in gene expression could contribute to the ADHD‐like symptoms of rat models and possibly the pathophysiology of ADHD in humans. © 2011 Wiley‐Liss, Inc.
Electrocorticographic control of a prosthetic arm in paralyzed patients
Authors: Yanagisawa Takufumi , Hirata Masayuki , Saitoh Youichi , Kishima Haruhiko , Matsushita Kojiro , Goto Tetsu , Fukuma Ryohei , Yokoi Hiroshi , Kamitani Yukiyasu , Yoshimine Toshiki
Published: August 2011

Objective:

Paralyzed patients may benefit from restoration of movement afforded by prosthetics controlled by electrocorticography (ECoG). Although ECoG shows promising results in human volunteers, it is unclear whether ECoG signals recorded from chronically paralyzed patients provide sufficient motor information, and if they do, whether they can be applied to control a prosthetic.

Methods:

We recorded ECoG signals from sensorimotor cortices of 12 patients while they executed or attempted to execute 3 to 5 simple hand and elbow movements. Sensorimotor function was severely impaired in 3 patients due to peripheral nervous system lesion or amputation, moderately impaired due to central nervous system lesions sparing the cortex in 4 patients, and normal in 5 patients. Time frequency and decoding analyses were performed with the patients' ECoG signals.

Results:

In all patients, the high gamma power (80–150Hz) of the ECoG signals during movements was clearly responsive to movement types and provided the best information for classifying different movement types. The classification performance was significantly better than chance in all patients, although differences between ECoG power modulations during different movement types were significantly less in patients with severely impaired motor function. In the impaired patients, cortical representations tended to overlap each other. Finally, using the classification method in real time, a moderately impaired patient and 3 nonparalyzed patients successfully controlled a prosthetic arm.

Interpretation:

ECoG signals appear useful for prosthetic arm control and may provide clinically feasible motor restoration for patients with paralysis but no injury of the sensorimotor cortex. ANN NEUROL 2012;
Zwitterionic ring opening polymerization of lactide by metal free catalysts: Production of cyclic polymers
Authors: Prasad Aitha Vishwa , Stubbs Ludger Paul , Ma Zhun , Yinghuai Zhu
Published: August 2011

Tailor made N‐heterocyclic carbene (NHC) catalyst precursors namely (+) and (−) 1‐methyl‐3‐menthoxymethyl imidazolium chloride have been synthesized in high yield with a literature modified procedure. A reaction of catalyst precursor with potassium tert butoxide in situ generates the NHC catalyst. The zwitterionic ring opening polymerization of lactide (LA) mediated by a catalytic system composed of NHC catalyst at 25°C under argon atmosphere led to a cyclic poly(lactide) of a high molecular weight with a narrow molecular weight distribution. The cyclic poly(lactide) was characterized by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Matrix‐assisted laser desorption ionization‐time of flight mass spectrometry (MALDI‐TOF MS). The NHC catalysts are active for lactide polymerization in the presence of air and elevated temperatures at 55°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Dielectric relaxation and Schottky conduction of IR laser irradiated Makrofol‐DE polycarbonate
Authors: Hanafy Taha A.
Published: August 2011

The effect of IR laser pulses on the dielectric properties, X‐ray diffraction, Fourier transform infrared spectroscopy (FTIR), and I–V characteristics of Makrofol‐DE 1‐1 CC polycarbonate has been investigated in the temperature and frequency ranges of 300–375K and 10 kHz–4 MHz, respectively. IR laser fluencies are set from 0.47 to 7.07 J/cm2. Three relaxation processes namely, α, β, and γ have been obtained. The first process is due to the micro Brownian motion of the segmental parts of the main chain. The second process was assigned to the local motion of the dipoles within the crystalline phases of the sample. The third one was attributed to the crank shaft motion along the main chains of the Makrofol. X‐ray diffraction and FTIR spectroscopy have revealed that the irradiation of Makrofol at the fluence range 0.94–7.07 J/cm2 causes crosslinking formation inside the sample. Reduction in crystallinity of Makrofol at higher IR laser doses is due to the crosslinking formation taking place within polymer matrix. At higher voltage, the conduction mechanism of Makrofol‐DE was identified as Shottky type. The attained results suggested strongly the applicability of Makrofol‐DE in IR laser pulses dosimetry. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Quantitative determination of degree of conversion in photocured poly(urethane‐dimethacrylate)s by Fourier transform infrared spectroscopy
Authors: Barszczewska‐Rybarek Izabela M.
Published: August 2011

In this work, infrared spectroscopy was used to characterize the degree of double bonds conversion (DC) in six series of poly(urethane‐dimethacrylate)s, derived from dicarbamates of oligoethylene glycols monomethacrylates and aliphatic, cycloaliphatic and aromatic diisocyanates. To evaluate the degree of conversion in polymers devoid of aromatic moieties, two methods of calculation have been proposed: internal band ratio method, with carbonyl stretching vibrations as a standard, and a method involving the direct observation of the decrease in the intensity of CC stretching band. The validity of these methods has been checked on polymers with aromatic structures, by comparing the results with those obtained by the internal band ratio method applying an aromatic band as a reference. A good correlation between the degree of conversion from two internal standard methods, using aromatic band and carbonyl band as references, was obtained. It was shown that the degree of conversion increases as the number of oxyethylene units increases. Polymerization of monomers with aliphatic cores resulted in higher DC values, while those with cycloaliphatic and aromatic cores—resulted in lower DC values. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Nanosilica filled poly(glycerol‐sebacate‐citrate) elastomers with improved mechanical properties, adjustable degradability, and better biocompatibility
Authors: Wu Yan , Shi Rui , Chen Dafu , Zhang Liqun , Tian Wei
Published: August 2011

Modified nano‐fumed silica (mn‐silica)/poly(glycerol‐sebacate‐citrate), in which mn‐silica loadings varied from 0 to 20 phr, were prepared by in situ polymerization and surface modification. The influence of mn‐silica loadings on the structure and properties of the composites was studied. Scanning electron microscope (SEM) and transmission electron microscope (TEM) photos showed that the mn‐silica dispersed well as nano‐scale network in the matrix, and exhibited good interfacial bonding with the matrix. The mn‐silica filled composites exhibited excellent comprehensive properties relative to the unfilled elastomers. Specially, the tensile strength improved from 0.9 MPa to 5.3 MPa. Results of the in vitro degradation test suggested that mn‐silica loading could adjust the degradation rate of the composites in simulated body fluid solution. The MTT colorimetry with L929 cells substantiated that the introduction of mn‐silica weakened the cytotoxicity of elastomers and made the composites accepted as qualified biomedical materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Simulation of crystallization kinetics and morphology during nonisothermal crystallization in short fiber reinforced composites
Authors: Ruan Chunlei , Ouyang Jie
Published: August 2011

Computer simulation for the nonisothermal crystallization of short fiber reinforced composites is presented. The pixel coloring technique is implemented to the study of crystal morphology evolution as well as the crystallization kinetics. A parametric study is used to explore the influences of thermal conditions and fibers on the crystallization in the reinforced system. We particularly focus on the roles of cooling rate, initial temperature, nucleation density on fibers, fiber content, fiber length, and fiber diameter. The results indicate that cooling rate is a significant factor to the crystallization kinetics as well as the morphology. The initial temperature only affects the crystallization kinetics and has minor impact on the morphology. The additional fibers have a dual effect on the crystallization. They depress the crystallization rate by hindering the spherulitic growth and accelerate the crystallization rate by providing nucleation sites. The constraining effect is mainly dependent on fiber content, whereas the enhancing effect is mainly determined by fiber surface and fiber nucleation density as well as surface nucleation mode. Present results are hoping to give more insight about the crystallization in short fiber reinforced composites and be more helpful to the industrial application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of dendritic polyaniline nanofibers by using soft template of sodium alginate
Authors: Bhowmick Biplab , Bain Mrinal Kanti , Maity Dipanwita , Bera Nirmal Kumar , Mondal Dibyendu , Mollick Md. Masud Rahaman , Maiti Prabir Kumar , Chattopadhyay Dipankar
Published: August 2011

Highly crystallized polyaniline (PANI) nanofibers were synthesized by oxidative polymerization of aniline in the presence of sodium alginate as a soft template in HCl and ammonium peroxydisulfate (APS) acting as an oxidizing agent. Sodium alginate, in presence of a protonic acid like HCl, formed hydrogen bonds with anilium ions or oligomers. The formed hydrogen bonds provide the driving force to form PANI nanofibers. The nanofibers were separated from the alginate gel by degelling with ammonium hydroxide and during degelling emeraldine salt was converted into emeraldine base form. The polymerized PANI was characterized using ultraviolet (UV)–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). UV and FTIR spectra showed that the presence of sodium alginate had no effect on the electronic state and backbone structures of the resulting PANI products. It was evident from the XRD analysis that the obtained PANI nanofibers exhibit higher crystalline order. SEM micrographs showed that PANI nanofibers were just like a mat of interwoven twisted nanofibers. After magnification of the SEM image, it was found that most of the nanofibers were interconnected to form ramose structures rather than isolated nanofibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of NBR on epoxy/glass prepregs properties
Authors: Galledari Nasim Abuali , Beheshty Mohammad Hosain , Barmar Mohammad
Published: August 2011

Solid acrylonitrile‐butadiene rubber (NBR) was used in epoxy resin for toughening and also for increasing the tack of epoxy/glass prepregs. The NBR used in this study was a rubber with 33% acrylonitrile content. The changes in thermal and mechanical properties such as glass transition temperature (Tg), curing characteristics and lap‐shear strength have been studied. For this purpose, three types of prepregs with two levels of NBR content of 3 and 5%, were prepared. Prepregs were made by solvent type impregnation apparatus. In this method, resin impregnates satin textile glass fiber under the controlled and constant condition of line speed and oven temperature. Prepregs were B‐staged for about 3%. The cure characterization, Tg and flow behavior were evaluated using differential scanning calorimetry and rheological analysis. Results showed that increasing the rubber content caused the following effects: (a) delay in gel time of prepregs, (b) increase in activation energy of prepregs, and (c) decrease in total heat of curing reaction. It is interesting that NBR increased the tack of epoxy/glass prepreg but, had no effect on its resin flow behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Melt processability of polytetrafluoroethylene: Effect of melt treatment on tensile deformation mechanism
Authors: Li Min , Zhang Wei , Wang Chaosheng , Wang Huaping
Published: August 2011

It is widely accepted that the melt processibility of polytetrafluoroethylene (PTFE) is poor. In this article, a high‐molecular‐weight PTFE was extruded smoothly with a modified die; and critical shear rate could be raised to 4 s−1, using a die with L/D (length to diameter) ratio of 200. Meanwhile, we compared the current PTFE fiber spinning method with melt spinning to investigate the effects of high‐temperature treatment on the drawability of PTFE and found that the processing sequence could play a key role. The deformation imposed before or after the high‐temperature treatment could determine whether the fibrillation can be achieved continuously and effectively. Based on the experiment phenomenon, together with the results of differential scanning calorimetry, X‐ray diffraction, and scanning electron microscopy characterization, we proposed a model to describe the submicron structural change of PTFE during extension. From this model, the fundamental mechanism for the poor melt processibility of PTFE was elucidated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Compression wood as a source of reinforcing filler for thermoplastic composites
Authors: Buyuksari Umit , Ayrilmis Nadir , Akbulut Turgay
Published: August 2011

Compression wood (CW) is a reaction wood formed in gymnosperms in response to various growth stresses. Many of the anatomical, chemical, physical, and mechanical properties of CW differ distinctly from those of normal wood. Because of different properties, the CW is much less desirable than normal wood. This study was conducted to investigate the suitability of CW flour obtained from black pine (Pinus nigra Arnold) in the manufacture of wood plastic composite (WPC). Polypropylene (PP) and CW flour were compounded into pellets by twin‐screw extrusion, and the test specimens were prepared by injection molding. WPCs were manufactured using various weight percentages of CW flour/PP and maleic anhydride‐grafted PP (MAPP). Water absorption (WA), modulus of rupture (MOR), and modulus of elasticity (MOE) values were measured. The results showed that increasing of the CW percentage in the WPC increased WA, MOR, and MOE values. Using MAPP in the mixture improved water resistance and flexural properties. CW flour of black pine can be used for the manufacturing of WPC as a reinforcing filler. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis, characterization, and degradation investigation of water‐soluble β‐cyclodextrin‐based epoxy resins
Authors: Kang Nianjun , Du Zhongjie , Li Hangquan , Zhang Chen , Zhao Zhehan
Published: August 2011

A series of β‐cyclodextrin‐based epoxy resins were synthesized with different epoxy equivalent weights. Their chemical structures were characterized with Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance Spectroscopy (NMR) examination. These epoxy resins were cured using L‐arginine as a curing agent, and the degradation behavior of the cured resins was evaluated under different acidic buffer solutions at 37°C. The degradable behavior of such epoxy resins suggested potential applications as environment friendly materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Temperature effect on the swelling of PAAm‐κ‐carrageenan composites
Authors: Evingür G. Akın , Pekcan Ö.
Published: August 2011

The steady‐state fluorescence (SSF) technique was used for studying swelling of disc‐shaped polyacrylamide (PAAm)‐κ‐carrageenan (κC) composites which were prepared by free‐radical crosslinking copolymerization at 80°C. Pyranine was introduced as a fluorescence probe during polymerization. Swelling experiments were performed in water at various temperatures by real‐time monitoring of the pyranine (Py) fluorescence intensity, I which decreased as swelling proceeded. Stern–Volmer equation is modified for low quenching efficiencies to interpret the behavior of Py intensity during the swelling of PAAm‐κC composites. The Li‐Tanaka equation was used to determine the swelling time constants, τ1, and cooperative diffusion coefficients, D0, from fluorescence intensity, weight, and volume variations of the composites at various temperatures. It was observed that τ1 first decreased up to 40°C and then increased; naturally, D0 increased up to 40°C and then decrease for all κC content gels. Swelling activation energies, ΔE, were measured for the swelling composites, which are found to be exothermic and endothermic in between 30–40 and 40–60°C, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Development and assessment of the advanced graft copolymers obtained from Hibiscus sabdariffa biomass
Authors: Chauhan Ashish , Kaith Balbir
Published: August 2011

In this article, the morphological transformation in Hibiscus sabdariffa stem fiber through graft copolymerization with effective ethyl acrylate (EA) and its binary vinyl monomeric mixtures using ceric ammonium nitrate—nitric acid initiator system has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to obtain the maximum graft yield (117.3%). The optimized reaction parameters were then used to screen the additive effect of EA with n‐butyl acrylate (BA), acrylic acid (AA), and 4‐vinyl pyridine (4‐VP) in binary vinyl monomer mixtures on percentage grafting, properties, and the behavior of the fiber. The graft copolymers were characterized by FTIR, SEM, XRD, TGA, and DTA techniques and evaluated for physico‐chemical changes. With increase in the Pg a significant physico‐chemico‐thermal resistance, miscibility in organic solvents, hydrophobicity were found to increase, whereas crystallinity, crystallinity index, dye‐uptake, and hydrophylicity decreased, however, the cellulose form I remained unchanged. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of cationic UV‐curable methacrylate copolymers and properties of the cured films of their composites with alicyclic epoxy resin
Authors: Tang Chunyi , Liu Weiqu
Published: August 2011

Cationic UV‐curable methacrylate copolymers consisting of glycidyl methacrylate, iso‐butyl methacrylate, and 2,2,3,4,4,4‐hexafluorobutyl methacrylate were synthesized, and their structures were characterized by FTIR, 1H NMR, and 13C NMR. A series of UV‐cured composite films based on the synthesized copolymers and an alicyclic epoxy resin, 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexanecarboxylate (CE) were obtained through photopolymerization. Their surface contact angle, chemical ability, gloss, light transmittance, thermal behavior, micromorphology, and shrinkage were investigated. Results indicated that these cured resins showed excellent gloss and visible light transmittance; after the combination of the copolymers and CE, and in the presence of fluorine in the curing systems they exhibited relatively fine water resistance, chemical, and thermal stability. It was observed that these copolymers could decrease the degree of the volume shrinkage to CE. The UV‐curable materials may have promising applications in optical fiber coatings, flip chip and Organic Light‐Emitting Diode (OLED) packing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Cone calorimeter study of inorganic salts as flame retardants in polyurethane adhesive with limestone filler
Authors: Lindholm Johan , Brink Anders , Wilén Carl‐Eric , Hupa Mikko
Published: August 2011

A cone calorimeter was used to test inorganic water‐releasing and low‐melting compounds as flame retardants in polyurethane adhesive samples. Sodium metasilicate pentahydrate, potassium carbonate mixed with silica gel, sodium hydrogen carbonate, calcium oxalate monohydrate, zinc and magnesium chloride mixed with potassium chloride, aluminium and magnesium hydroxides, ammonium polyphosphate (APP), sodium and potassium phosphates were tested. These additives were used to partially (10–20%) replace the limestone used as a filler in the adhesive. Thermogravimetric analysis was used to study decomposition and melting of the inorganic compounds. The results showed that sodium metasilicate monohydrate formed a protective layer of sodium silicate on the sample surface, significantly delaying the time to ignition. Addition of APP resulted in the lowest overall heat release rate curve. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Comparison of UF synthesis by alkaline‐acid and strongly acid processes
Authors: Ferra João M. M. , Henriques Ana , Mendes Adélio M. , Costa Mário Rui N. , Carvalho Luisa H. , Magalhães Fernão D.
Published: August 2011

This work discusses two processes for producing urea‐formaldehyde (UF) resins. One is the alkaline‐acid process, which has three steps: usually an alkaline methylolation followed by an acid condensation and finally the addition of a final amount of urea. The other process, the strongly acid process, consists of four steps, in which the first step involves a strongly acid condensation followed by an alkaline methylolation, a second condensation under a moderately acid pH and finally, methylolation and neutralization under a slight alkaline pH. Two resins were produced using the two above described processes. The molecular weight distribution (MWD) of the resins was monitored off‐line by GPC/SEC and the final resins were characterized by GPC/SEC and HPLC. These studies showed that the two resins differ greatly in chemical structure, composition, viscosity, and reactivity. The monitoring of MWD indicated that the first condensation under a strongly acid environment leads to the production of a polymer with a distinctly different chemical structure, therefore increasing the flexibility of polymer synthesis and opening the way to the improvement of end‐use properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Crystallization, dispersion behavior and the induced properties through forming a controllable network in the crosslinked polyester‐SiO2 nanocomposites
Authors: Guo Wang Yu , Chuan Ke Yang
Published: August 2011

The poly(ethylene terephthalate) (PET) crosslinked copolymers (G‐PET) with glycerol (GC) and their novel nanocomposite samples (GNPET) were reported and investigated. The nanoparticle dispersion behavior was creatively stabilized with the crosslinked network. Several interesting properties and phenomena including the abnormal crystallization behavior of GNPET samples were presented. Results of differential scanning calorimeter proved that the thermal and crystallization behavior of GNPET samples was effectively tuned with GC load. The obviously enhanced crystallization and nanoparticle homogenous dispersion behavior appeared at 2 wt % SiO2 and 0.2 wt % GC load. Polarized optical microscopy (POM) results showed that the spherulite growth rate of the GNPET samples with 0.1 wt % GC load sharply decreased from 0.0562 to 0.0157 μm s−1 with 0.5 wt % GC load. As GC load increased, the spherulite size of GNPET samples decreased greatly so as to be much smaller than that of pure PET nanocomposites. Water absorbing experiments presented that the higher GC load created the lower water diffusion behavior but higher barrier against water, gas, and light. A model was proposed to state the network immobilization effect on the nanoparticle dispersion, and the restraining effect on PET chain mobility and crystal size growth which were related to the above properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Morphology and properties of nylon 6 and high density polyethylene blends in presence of nanoclay and PE‐g‐MA
Authors: Mallick Sumana , Kar Prativa , Khatua B. B.
Published: August 2011

In this study, we report the synergistic effect of nanoclay and maleic anhydride grafted polyethylene (PE‐g‐MA) on the morphology and properties of (80/20 w/w) nylon 6/high density polyethylene (HDPE) blend. Polymer blend nanocomposites containing nanoclay with and without compatibilizer (PE‐g‐MA) were prepared by melt mixing, and their morphologies and structures were examined with scanning electron microscopy (SEM) and wide angle X‐ray diffractometer (WAXD) study. The size of phase‐separated domains decreased considerably with increasing content of nanoclay and PE‐g‐MA. WAXD study and transmission electron microscopy (TEM) revealed the presence of exfoliated clay platelets in nylon 6 matrix, as well as, at the interface of the (80/20 w/w) nylon 6/HDPE blend–clay nanocomposites. Addition of PE‐g‐MA in the blend–clay nanocomposites enhanced the exfoliation of clays in nylon 6 matrix and especially at the interface. Thus, exfoliated clay platelets in nylon 6 matrix effectively restricted the coalescence of dispersed HDPE domains while PE‐g‐MA improved the adhesion between the phases at the interface. The use of compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Mechanical, barrier, and interfacial properties of biodegradable composite films made of methylcellulose and poly(caprolactone)
Authors: Khan Ruhul A. , Salmieri Stephane , Dussault Dominic , Sharmin Nusrat , Lacroix Monique
Published: August 2011

Methylcellulose (MC) films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol, and 0.025% Tween®80. Poly(caprolactone) (PCL) films were prepared by compression molding from its granules. Biodegradable composite films were fabricated using MC film as reinforcing agent and PCL as the matrix material by compression molding. One layer of MC film was reinforced with two layers of PCL films. The MC content in the composites was varied from 10 to 50% by weight. Mechanical, barrier, and degradation properties of PCL, MC, and composite films were evaluated. The values of puncture strength (PS), puncture deformation (PD), viscoelasticity (Y) coefficient, and water vapor permeability (WVP) of the composites (50% MC content) were found to be 124.3 N/mm, 3.2 mm, 31%, and 2.6 g·mm/m2·day·kPa, respectively. Oxygen transmission rate (OTR) of PCL, MC, and composites (50% MC) were found to be 175, 25, 22 cc/m2/d, respectively, which indicated that composite films showed significantly lower OTR than PCL films. Degradation tests of the composite films (50% MC) were performed for 6 weeks in aqueous medium (at 25°C), and it was found that composites lost its mass slowly with time. After 6 weeks, mass and PS of the composites were decreased to 13.4 and 12%, respectively. Composite interface was studied by scanning electron microscopy (SEM). The MC film had good adhesion with PCL matrix during compression molding and suggested strong interface of the composite system. SEM image after 6 weeks of degradation showed some openings in the interface and revealed slow degradation of the MC films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Structural and mechanical properties of needle‐punched nonwoven reinforced composites in erosive environment
Authors: Tejyan Sachin , Patnaik Amar , Rawal Amit , Satapathy Bhabani K.
Published: August 2011

Polypropylene‐based needle‐punched nonwoven reinforced epoxy composites have been fabricated and were evaluated for their thermomechanical response and dry erosion performance. The erosive wear investigations were carried out using silica sand particles as erodent with varying impact velocity, angles of impingement, fiber content, and stand‐off‐distance as the operating variables. Design of experiments (DoE) approach‐based Taguchi analysis was carried out to establish the interdependence of operating parameters and erosion rate. Impingement angle and impact velocity have been found to be the most significant determinants of erosive wear performance of such nonwoven reinforced composites. The composites were also observed to be appreciably resistant to impact content and indentations in addition to exhibiting the absence of any storage‐modulus decay till 60°C accompanied with a nominal increase in the primary transition temperature as revealed from loss‐tangent peaks. The composite with 30 wt % and 40 wt % of nonwoven materials have shown the highest and lowest erosion rates, respectively. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM) and their possible erosion mechanisms are discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Adsorptive removal of technetium‐99 using macroporous poly(GMA‐co‐EGDMA) modified with diethylene triamine
Authors: Hercigonja Radmila V. , Maksin Danijela D. , Nastasović Aleksandra B. , Trifunović Snežana S. , Glodić Pavle B. , Onjia Antonije E.
Published: August 2011

The possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO4−) and the sorption kinetics for removing TcO4− from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO4− by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO4− (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g−1 and 1698 mL g−1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Immunohistochemical identification and synaptic inputs to the diffuse bipolar cell type DB1 in macaque retina
Authors: Puthussery Theresa , Gayet‐Primo Jacqueline , Taylor W. Rowland , Haverkamp Silke
Published: August 2011

Detailed analysis of the synaptic inputs to the primate DB1 bipolar cell has been precluded by the absence of a suitable immunohistochemical marker. Here we demonstrate that antibodies for the EF‐hand calcium‐binding protein, secretagogin, strongly label the DB1 bipolar cell as well as a mixed population of GABAergic amacrine cells in the macaque retina. Using secretagogin as a marker, we show that the DB1 bipolar makes synaptic contact with both L/M as well as S‐cone photoreceptors and only minimal contact with rod photoreceptors. Electron microscopy showed that the DB1 bipolar makes flat contacts at both triad‐associated and nontriad‐associated positions on the cone pedicle. Double labeling with various glutamate receptor subunit antibodies failed to conclusively determine the subunit composition of the glutamate receptors on DB1 bipolar cells. In the IPL, DB1 bipolar cell axon terminals expressed the glycine receptor, GlyRα1, at sites of contact with AII amacrine cells, suggesting that these cells receive input from the rod pathway. J. Comp. Neurol. 519:3640–3656, 2011. © 2011 Wiley‐Liss, Inc.
Dynamic responses of Xenopus retinal ganglion cell axon growth cones to netrin‐1 as they innervate their in vivo target
Authors: Shirkey Nicole J. , Manitt Colleen , Zuniga Liliana , Cohen‐Cory Susana
Published: August 2011

Netrin‐1 influences retinal ganglion cell (RGC) axon pathfinding and also participates in the branching and synaptic differentiation of mature RGC axons at their target. To investigate whether netrin also serves as an early target recognition signal in the brain, we examined the dynamic behavior of Xenopus RGC axons soon after they innervate the optic tectum. Time‐lapse confocal microscopy imaging of RGC axons expressing enhanced yellow fluorescent protein demonstrated that netrin‐1 is involved in early axon branching, as recombinant netrin‐1 halted further advancement of growth cones into the tectum and induced back branching. RGC growth cones exhibited differential responses to netrin‐1 that depended on the degree of differentiation of the axon and the developmental stage of the tadpole. Netrin‐1 decreased the total number of branches on newly arrived RGC growth cones at the target, but increased the dynamic branching of more mature arbors at the later developmental stage. To further explore the response of axonal growth cones to netrin, Xenopus RGC axons were followed in culture by time‐lapse imaging. Exposure to netrin‐1 rapidly increased the forward advancement of the axon and decreased the size and expanse of the growth cone, while also inducing back branching. Taken together, the differential in vivo and in vitro responses to netrin‐1 suggest that netrin alone is not sufficient to induce the cessation of growth cone advancement in the absence of a target but can independently modulate axon branching. Collectively, our findings reveal a novel role for netrin on RGC axon branch initiation as growth cones innervate their target. © 2011 Wiley Periodicals, Inc. Develop Neurobiol 72: 628–648, 2012