bluuebunny/crossref_metadata_2025 huggingface dataset:
Bayesian Training and Committees of State-Space Neural Networks for Online Travel Time Prediction
Authors: van Hinsbergen C. P. IJ. , van Lint J. W. C. , van Zuylen H. J.
Published: October 2009

This paper presents the Bayesian evidence framework that enables a unified way of constructing and training committees of an arbitrary number of models. The main contribution the paper makes is an expansion of this framework for recurrent neural networks, which involves analytically deriving the gradient and the Hessian of the network. State-space neural networks (SSNNs), a special type of recurrent neural networks, are compared with feed-forward neural networks (FFNNs), and the effect of the Bayesian framework on both types is investigated using data from a densely used freeway in the Netherlands. From a cross-validation procedure, it can be concluded that, for a short time horizon, both Bayesian training and recurrency do not lead to improvements, but that, for a longer horizon, both techniques are beneficial. It is shown that the use of a committee leads to improved performance; furthermore, the correlation of the evidence factor, which follows from Bayesian model-fitting, and the generalization performance is compared against the training error and the generalization performance. It is found that the evidence has lower correlation, which is an indication that ( a) the data set may be too small, ( b) bias exists, ( c) the mapping between the input and output data is difficult, and ( d) the approximation of the evidence is imperfect. Future research will need to resolve these issues. However, the Bayesian framework will already be beneficial to more complex problems and lead to estimations of error bars on the predictions, which may be useful for many applications.
Kinematic Terrestrial Light-Detection and Ranging System for Scanning
Authors: Glennie Craig
Published: October 2009

Highway corridor surveys are becoming more difficult and expensive to carry out because of the need to minimize lane closures, traffic disruptions, and safety hazards posed to the surveyors and public. Roadway surveyors are at risk when working in the traffic corridor if they are unable to move with the flow of traffic. Safety for the traveling public is also a concern when lanes are closed or blocked by slow-moving vehicles. Costs for the placement of safety features to protect a survey crew can in some instances be greater than the cost of the survey itself. To mitigate these problems, a survey data acquisition tool is needed that can collect topographic and infrastructure information without disrupting traffic flow. Terrapoint has developed a novel kinematic laser scanning system that can be deployed on a passenger vehicle or small watercraft. Light-detection and ranging (LIDAR) digital imagery and video are collected from the survey platform while it is moving at traffic speeds. The system is georeferenced with a high-accuracy Global Positioning System–inertial measurement unit. Terrapoint's mobile LIDAR scanner has successfully surveyed existing highway corridors all over North America. It has also proven sufficiently accurate for scanning airport runway surfaces so as to predict areas where water will pool. Moving with the traffic flow and not requiring an escort, the system scans a 360° swath that includes the pavement surface and objects to the sides and above the survey vehicle.
Chiral amplification in a cyanobiphenyl nematic liquid crystal doped with helicene-like derivatives
Authors: Ferrarini Alberta , Pieraccini Silvia , Masiero Stefano , Spada Gian Piero
Published: October 2009

The addition of a chiral non-racemic dopant to a nematic liquid crystal (LC) has the effect of transferring the molecular chirality to the phase organization and a chiral nematic phase is formed. This molecular chirality amplification in the LC provides a unique possibility for investigating the relationship between molecular structure, intermolecular interactions, and mesoscale organization. It is known that axially chiral or helical-shaped molecules with reduced conformational disorder are good candidates for high helical twisting power derivatives. In particular, biaryl derivatives are known to be efficient chiral inducers in biaryl nematic mesophases. In this paper, we focus on a new series of helicene-like molecules of known absolute configuration. We have integrated cholesteric pitch measurements with geometry optimization by DFT calculations and analysis of the twisting ability by the Surface Chirality model to shed light on the structural features responsible for the analogies and differences exhibited by these derivatives. The investigation of these dopants with well-defined geometry, by virtue of the low conformational freedom, and the substituents variously distributed around the core, allows us to extend our knowledge of the molecular origin of the chirality amplification in liquid crystals and to confirm the simple relationship “molecular P-helicity” → “cholesteric P-handedness” for helical-shaped helicene-like derivatives.
A convenient method for preparing rigid-core ionic liquid crystals
Authors: Fouchet Julien , Douce Laurent , Heinrich Benoît , Welter Richard , Louati Alain
Published: October 2009

An efficient, solvent free method for the N-arylation of imidazole by 1-(dodecyloxy)-4-iodobenzene using Cu(II)-NaY as catalyst and K2CO3 as base is reported. By this synthetic approach, mesomorphic 3-[4-(dodecyloxy)phenyl]-1-methyl-1H-imidazol-3-ium iodide was synthesized in a two-step procedure, and its mesomorphism has been fully investigated by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. In addition its lamellar crystal structure, electrochemical behaviour and UV (absorption and emission) properties are reported.
Isolation and characterisation of selected lactic acid bacteria for improved processing ofNem chua, a traditional fermented meat from Vietnam
Authors: Nguyen H. , Elegado F. , Librojo-Basilio N. , Mabesa R. , Dizon E.
Published: October 2009

Nem chua is a traditional lactic acid fermented meat of Vietnam that is consumed raw. During fermentation, the number of acid-producing bacteria increased significantly and by the final day (4th), it had reached approximately 8.4 log cfu/g, contributing to 94% of the total microbiota of the product. Out of 85 isolates obtained from the product, only 44 were confirmed Gram-positive and catalase-negative. These putative LAB isolates were purified and screened for antimicrobial and proteolytic activity. None of the isolates showed bacteriocin activity using the 'spot-on lawn' method, but showed antimicrobial activity against Lactobacillus sakei and Enterococcus faecium using deferred assay. Four isolates showed good proteolytic activities at pH 7.0. These isolates were identified as Lactobacillus plantarum using an API 50 CHL i.d. kit. Sequencing of the partial 16S rRNA gene amplified by primers 1101F (5'-AACGAGCGCAACCC-3') and 1407R (5'-GACGGGCGGTGTGTAC-3') showed 98% homology to Lactobacillus plantarum WCFS1.
Antimicrobial susceptibility of Lactobacillus rhamnosus
Authors: Korhonen J. , Van Hoek A.H. , Saarela M. , Huys G. , Tosi L. , Mayrhofer S. , Wright A. Von
Published: October 2009

We aimed to determine the minimum inhibitory concentrations (MICs) of Lactobacillus rhamnosus (n=75) strains, to study their antibiotic resistance genes with microarray, and to assess the microbiological cut-off values of tested antimicrobial agents. L. rhamnosus strains were tested with agar dilution, broth microdilution and Etest methods for ampicillin, clindamycin, erythromycin, gentamicin, streptomycin, and tetracycline using specific LSM medium. Most of the L. rhamnosus strains were found phenotypically susceptible to all six antibiotics tested. Four of the strains were phenotypically multiresistant, three strains to clindamycin, erythromycin and streptomycin and one strain to streptomycin and tetracycline. Some of the resistant (n=8) and susceptible (n=5) strains were further studied with a microarray method to reveal the antibiotic resistance genes behind the phenotypic resistances. From our experience, we recommend that microbiological cut-off values should be proposed according to the method used.
Development and Testing of a Portfolio Evaluation Scoring Tool
Authors: Karlowicz Karen A.
Published: October 2009

This study focused on development of a portfolio evaluation tool to guide the assignment of valid and reliable scores. Tool development was facilitated by a literature review, guidance of a faculty committee, and validation by content experts. Testing involved a faculty team that evaluated 60 portfolios. Calculation of interrater reliability and a paired-samples
t
test were used to judge effectiveness. Interrater reliability was 0.78 for overall scores, 0.81 for the seven program outcomes criteria scores, and more than 0.65 for scores assigned by 11 of 13 pairs of raters. There were no significant differences between raters' scores in 10 of 13 pairs. The portfolio evaluation tool demonstrated high reliability and should be tested by other schools using portfolio evaluation.
Equivalence Testing of Traditional and Simulated Clinical Experiences: Undergraduate Nursing Students' Knowledge Acquisition
Authors: Schlairet Maura C. , Pollock Jane W.
Published: October 2009

Although simulated clinical experience is being used increasingly in nursing education, vital evidence related to knowledge acquisition associated with simulated clinical experience does not exist. This intervention study used a 2×2 crossover design and equivalence testing to explore the effects of simulated clinical experiences on undergraduate students' (
n
= 74) knowledge acquisition in a fundamentals of nursing course. Following random assignment, students participated in laboratory-based simulated clinical experiences with high-fidelity human patient simulators and traditional clinical experiences and completed knowledge pretests and posttests. Analysis identified significant knowledge gain associated with both simulated and traditional clinical experiences, with the groups' knowledge scores being statistically significantly equivalent. A priori equivalence bounds around the difference between the groups were set at ±5 points. Simulated clinical experience was found to be as effective as traditional clinical expe rience in promoting students' knowledge acquisition.
Incorporating Community-Based Clinical Experiences into a Maternal-Women's Health Nursing Course
Authors: Aurilio Louise A. , O'Dell Valerie M.
Published: October 2009

Many barriers to increasing enrollment in nursing programs currently exist. One barrier is increased competition for clinical site placement from competing nursing and multidisciplinary programs. A critical component of nursing educational programs is providing clinical experiences that reinforce didactic learning. Incorporating women's health in a maternity course required clinical experiences to reflect this content. Faculty incorporated new strategies to help students integrate relevant theoretical concepts of maternity and women's health nursing by placing students in more community sites. Although labor and delivery and mother-baby units are located in the hospital, a wealth of community experiences for maternal and women's health nursing students exists. This article discusses strategies implemented by faculty at Youngstown State University to meet these challenges and promote appropriate clinical learning experiences for student nurses enrolled in a maternal-women's health nursing course.
Meal Preparation: Comparing Treatment Approaches to Increase Acquisition of Skills for Adults with Schizophrenic Disorders
Authors: Grimm Erica Zielinski , Meus Jennifer Sturtevant , Brown Catana , Exley S. Megan , Hartman Susan , Hays Carole , Manner Terence
Published: October 2009

This pilot study was conducted to determine whether an occupational therapy intervention using an acquisitional frame of reference with a psychoeducational component resulted in greater functional outcomes in the improvement of meal preparation for adult clients with schizophrenic disorders than an intervention framed solely by acquisition. Eight participants who met the inclusion criteria and were randomly assigned to the control group or the experimental group completed the study. Occupational performance in this area was assessed before and after treatment by administering relevant portions of the Performance Assessment of Self-Care Skills. Analysis of data suggests a significant change in one of three areas evaluated. All participants' “level of independence” improved, indicating that clients required less assistance after occupational therapy intervention; however, the findings did not indicate that the acquisition plus psychoeducation resulted in better outcomes than acquisition alone.
Everyday Lives of People with Advanced Cancer: Activity, Time, Location, and Experience
Authors: la Cour Karen , Nordell Kersti , Josephsson Staffan
Published: October 2009

This study described and explored the everyday activities of people with advanced cancer in relation to time, location, social engagement, and experience. Forty-five adult participants with a diagnosis of advanced cancer were sampled from an oncology outpatient unit. Data were collected with a time use method that involved diaries and interviews. Data were analyzed using a software program describing time use combined with a constant comparative method. The results showed that the participants' days were spent mostly at home and were dominated by self-care and leisure, with social engagement limited to immediate family and close friends. The participants' daily rhythm was identified as closely linked to their experience of satisfaction and consisted of both routine and novel activities. For healthcare services, the results suggest a need for developing services to support people with severe illness in creating and maintaining personal rhythms.
Applying the criteria of Ulrich and Brockbank for the assessment of the role of human resources as a strategic business partner in a mining company
Authors: De Bruyn Lize , Roodt Gert
Published: October 2009

The aim of this study was to apply the 14 criteria of Ulrich and Brockbank for the assessment of the movement of a human-resource function from its current development phase to a strategic business-partner role. A qualitative method, based on casing, was adopted as the research strategy. Data were collected from members of the human-resource forum of an organisation through a semi-structured focus group, individual interviews and solicited document reviews. The collected data were analysed through open coding or thematic analyses. Findings indicated that the organisation’s human-resource function was moving from operational human-resource service provision to a more strategic focus.
Typicality effects on memory for voice: Implications for earwitness testimony
Authors: Mullennix J. W. , Ross A. , Smith C. , Kuykendall K. , Conard J. , Barb S.
Published: October 2009

The effects of voice typicality on voice recognition were examined. In an incidental task, participants were presented with consonant‐vowel‐consonant stimuli (with varying vowels) spoken by voices rated as high‐typical or low‐typical. One week later, they were brought back for a surprise voice recognition test where the target voice was presented along with low‐typical and high‐typical voice distracters. The results indicated that voice misidentifications occur, with many errors due to confusions of high‐typical voice targets with high‐typical target voices. The results show that voice typicality affects voice recognition accuracy and is an important factor to be considered in real‐life earwitness testimony situations. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and Thermoelectric Characterization of Bi2Te3 Nanoparticles
Authors: Scheele Marcus , Oeschler Niels , Meier Katrin , Kornowski Andreas , Klinke Christian , Weller Horst
Published: October 2009

Here, a novel synthesis for near monodisperse, sub‐10 nm Bi2Te3 nanoparticles is reported. A new reduction route to bismuth nanoparticles is described, which are then applied as starting materials in the formation of rhombohedral Bi2Te3 nanoparticles. After ligand removal by a novel hydrazine hydrate etching procedure, the nanoparticle powder is spark plasma sintered to a pellet with preserved crystal grain sizes. Unlike previous works on the properties of Bi2Te3 nanoparticles, the full thermoelectric characterization of such sintered pellets shows a highly reduced thermal conductivity and the same electric conductivity as bulk n‐type Bi2Te3.
Simple and Efficient Generation of White Light Emission From Organophosphorus Building Blocks
Authors: Romero‐Nieto Carlos , Durben Stefan , Kormos Ila M. , Baumgartner Thomas
Published: October 2009

This paper describes a structure–property study using two dithieno[3,2‐b;2′,3′‐d]phosphole building blocks for the generation of white light emission and the incorporation of these units in a single polystyrene material. The emission of one of the light‐emitting organophosphorus building blocks can efficiently be switched from orange to green by simple protonation of the amino functional groups that are part of the π‐conjugated scaffold. The resulting three components (blue, green, and orange) exhibit photophysical properties that allow for an efficient fluorescence resonance energy transfer (FRET) in the mixture/polymer and provide intense white fluorescence upon excitation of the blue component; the fluorescence is close to pure white in solution and similar to the emission of an incandescent light bulb in the thin film. The results nicely illustrate the intriguing features that can be obtained by exclusively using organophosphorus‐based organic electronic materials.
Dendritic Polyglycerols for Biomedical Applications
Authors: Calderón Marcelo , Quadir Mohiuddin Abdul , Sharma Sunil Kumar , Haag Rainer
Published: October 2009

The application of nanotechnology in medicine and pharmaceuticals is a rapidly advancing field that is quickly gaining acceptance and recognition as an independent area of research called “nanomedicine”. Urgent needs in this field, however, are biocompatible and bioactive materials for antifouling surfaces and nanoparticles for drug delivery. Therefore, extensive attention has been given to the design and development of new macromolecular structures. Among the various polymeric architectures, dendritic (“treelike”) polymers have experienced an exponential development due to their highly branched, multifunctional, and well‐defined structures. This Review describes the diverse syntheses and biomedical applications of dendritic polyglycerols (PGs). These polymers exhibit good chemical stability and inertness under biological conditions and are highly biocompatible. Oligoglycerols and their fatty acid esters are FDA‐approved and are already being used in a variety of consumer applications, e.g., cosmetics and toiletries, food industries, cleaning and softening agents, pharmaceuticals, polymers and polymer additives, printing photographing materials, and electronics. Herein, we present the current status of dendritic PGs as functional dendritic architectures with particular focus on their application in nanomedicine, in drug, dye, and gene delivery, as well as in regenerative medicine in the form of non‐fouling surfaces and matrix materials.
Modified frontal polymerization of poly(methyl methacrylate)
Authors: Villegas Armando García , Ocampo Miguel A. , Saldivar‐Guerra Enrique , García‐Gaitán Beatriz , Vivaldo‐Lima Eduardo , Luna‐Barcenas Gabriel
Published: October 2009

In this work, we propose a modified frontal polymerization method to build a uniform reaction front by gradually immersing the reacting mixture in a thermal bath. This scheme allows uniform materials to be obtained with nearly constant molecular weights and polydispersities and a low residual monomer concentration. A comparative study of the molecular weight distributions of poly(methyl methacrylate)s obtained by bulk polymerization, frontal polymerization, and frontal polymerization with the proposed gradual immersion is presented. Samples obtained by these methods show that materials obtained by bulk polymerization and by frontal polymerization are less uniform than those obtained by frontal polymerization with gradual immersion in a thermal bath. The obtained uniformity is directly related to a stabilizing effect of the reaction front by the gradual immersion of the reactor in a constant‐temperature bath and to a reduction in the reaction rate promoted by a moderate transfer agent concentration. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Sorption behavior of biodegradable polyurethanes with carbohydrate crosslinkers
Authors: Lalwani Renuka , Desai Sonal
Published: October 2009

Polyether–polyurethanes (PUs) with a series of carbohydrate crosslinkers: monosaccharide (glucose), disaccharide (fructose) and polysaccharide (starch), were synthesized. The kinetics of swelling was studied in industrially important solvents like toluene, xylene and chlorobenzene. The R value and diol / triol ratio were varied to study the effect on crosslink density and sorption. It was observed that the swelling extent increased with increasing concentration of crosslinker in the polymer. Interestingly the effect of diisocyanate concentration on extent of sorption varied with the type of carbohydrate used for crosslinking. Considering the effect of diisocyanate concentration, the PUs containing disaccharide sucrose showed greater solvent uptake. Though the sorption behaviours were different, the solubility parameters of all PUs were the same irrespective of the type and concentration of the crosslinkers. All the PUs were observed to be biodegradable with glucose containing PUs exhibiting highest weight loss. Scanning electron microscope revealed absence of phase segregation in all the PU systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Comparative study of nanocomposites of polyolefin compatibilizers containing kaolinite and montmorillonite organoclays
Authors: Villanueva Maria Pilar , Cabedo Luis , Lagarón José Maria , Giménez Enrique
Published: October 2009

This work studied the morphology and physical properties of nanocomposites of different ethylene copolymers and functionalized polyethylenes with two different types of organoclays, to assess the potential application of these fillers as reinforcing components in the design of polyethylene and other polyolefinic based nanocomposites with enhanced properties. A polyethylene‐grafted‐maleic anhydride (PEMA), a poly(ethylene‐co‐acrylic acid), a poly(ethylene‐co‐vinyl acetate), and an ionomer of poly(ethylene‐co‐methacrylic acid) containing a small fraction of polyamide 6 were used to prepare nanocomposites by melt compounding in internal mixer. Two different types of commercial clays were used to obtain nanocomposites with the same organoclay content (5 wt %), i.e., an organomodified montmorillonite and an organomodified kaolinite. The morphology was evaluated by wide angle X‐ray scattering, scanning electron microscopy, transmission electron microscopy, and optical microscopy. The thermal, mechanical and barrier properties were evaluated by differential scanning calorimetry and thermogravimetric analysis, tensile tests and oxygen transmission rate experiments, respectively. From the results, it was seen that PEMA and the ionomer are the best polymer matrices to disperse both organoclays under the conditions applied. Kaolinite and montmorillonite appeared to be dispersed in the nanorange, however, higher aspect ratio was observed for montmorillonite. The best improvements in thermal degradation and in mechanical reinforcement were shown for organomodified kaolinite nanocomposites. But the best improvements in thermo‐oxidative degradation and in oxygen barrier were seen for the nanocomposites with organomodified montmorillonite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A novel insulin oral delivery system assisted by cationic β‐cyclodextrin polymers
Authors: Huang Lan , Xin Jianyu , Guo Yuchao , Li Jianshu
Published: October 2009

This work describes a new oral pharmaceutical formulation of insulin that is complexed with cationic β‐cyclodextrin polymers (CPβCDs), and then encapsulated into alginate/chitosan microspheres, which are prepared by ionotropic pregelation/polyelectrolyte method. CPβCDs were synthesized through a one‐step polymerization of β‐cyclodextrin (βCD), epichlorohydrin, and choline chloride. CPβCDs have enhanced ability to complex with insulin due to the assistance of their polymeric chains, as well as the electrostatic interactions between insulin (negatively charged while pH>5.3) and quaternary ammonium groups of CPβCDs. The noncovalent inclusion complex formed between CPβCDs and insulin was analyzed by Fourier transform infrared and fluorescence emission spectra. With the increase of zeta potential of CPβCDs from 1.8 to 14.2 mV, the insulin association efficiency (AE) of current system was increased from 55.2 to 71.8%, whereas the AE of insulin‐loaded microspheres at the same condition was only 50.7%. The cumulative insulin release in simulated intestinal fluid was also higher than that of the insulin‐loaded microspheres and βCD‐insulin encapsulated microspheres. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Antibacterial oil‐based polyurethane films for wound dressing applications
Authors: Yücedag Ferhat , Atalay‐Oral Cigdem , Erkal Sibel , Sirkecioglu Ahmet , Karasartova Djursun , Sahin Fikret , Tantekin‐Ersolmaz Serife Birgül , Güner Fatma Seniha
Published: October 2009

As an alternative to petroleum‐based polyol, hydroxyl containing material was prepared from linseed oil for polyurethane synthesis. Hexamethylene di‐isocyanate (HMDI) and/or 4, 4′‐methylene diphenyl di‐isocyanate (MDI) were used as isocyanate source. The polymerization reaction was carried out without catalyst. Polymer films were prepared by casting‐evaporation technique. The MDI/HMDI‐based polyurethane and its films had higher Tg and better thermal property than that of the HMDI‐based one because of the existence of benzene ring in the polymer chain. Static water contact angle was determined to be 74° and 77.5° for HMDI and MDI/HMDI‐based films, respectively. Water adsorption was found to be around 2.6–3.6% for both films. In vitro degradation of polyurethanes in phosphate buffered saline at 37°C was investigated by gravimetric method. Fourier transform infrared spectroscopy and scanning electron microscopy were used for confirmation of degradation on the polymer surface. The degradation rate of the HMDI‐based polyurethane film was found higher than that of the MDI/HMDI‐based film. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films, and the polyurethane films investigated here was not cytotoxic. Silver‐containing films were prepared using Biocera A® as filler and were screened for their antibacterial performance against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and/or Bacillus subtilis. The films prepared with and without Biocera A® exhibited antibacterial activity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hydrogenation of NBR latex by diimide reduction using selenium catalysts
Authors: Schulz G. A. S. , Comin E. , de Souza R. F.
Published: October 2009

Acrylonitrile–butadiene rubber (NBR) latex was hydrogenated using diimide in the presence of selenium catalysts under an oxygen atmosphere. The process has been optimized and is extremely effective in the hydrogenation of NBR latex, with more than 3350 carbon–carbon double bonds reduced per atom of selenium in 5 h at 60°C. The amount of gel formed was controlled with gel inhibitors such as Irganox. This process constitutes a new route for obtaining totally hydrogenated acrylonitrile–butadiene polymer with low amounts of gel and very low amounts of selenium contaminants. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Thermomechanical and morphological properties of epoxy blends with hyperbranched polyester: Effect of the pseudo‐generation number
Authors: Cicala G. , Recca G.
Published: October 2009

The thermomechanical and morphological properties of some epoxy blends modified with hyperbranched polymers are reported. The effects of pseudo‐generation numbers, from the second to the fourth, were studied. All the hyperbranched polymers used had OH end groups. The blends were thoroughly characterized in both the unreacted and cured states. The unreacted blends, characterized by parallel plate rheometry and hot stage microscopy, revealed that pseudo‐generation number can have a profound effect both on the reactivity and the phase separation behavior. Analysis of the cured samples was carried out through scanning electron microscopy, dynamic mechanical tests, and fracture mechanics. The results supported some findings obtained from the analysis of the unreacted blends; and dynamic mechanical analysis helped shed more light on the phase separation behavior. Pseudo‐generation number also influenced the glass transitions of the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
New anionic surface‐active agent derived from wool proteins for hair treatment
Authors: Barba Clara , Scott Sonya , Kelly Rob , Luis Parra Jose , Coderch Luisa
Published: October 2009

An anionic surface‐active agent derived from wool proteins was developed as an alternative to the anionic surfactants extensively used in shampoo formulations. The physicochemical properties of this new surface‐active agent prepared form wool proteins and its application for human hair treatments were studied. This new product could be considered a new mild anionic surface‐active agent, as evidenced by the results found by the evaluation of its physicochemical properties. The new wool anionic surface‐active agent was shown to be very substantive to hair, coating the fiber surface, giving rise to a significant improvement in the mechanical properties of the hair fibers, and providing a certain damage‐prevention effect on the hair. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Chemical recycling of poly(vinyl chloride): Application of partially dehydrochlorinated poly(vinyl chloride) for producing a chemically modified polymer
Authors: de A. M. M. S. Machado Helena M. , Filho G. Rodrigues , De Assunção R. M. N. , Soares Heline M. , Cangani Ana P. , Cerqueira Daniel A. , Meireles Carla da S.
Published: October 2009

Poly(vinyl chloride) (PVC) pipes were chemically modified to produce a sulfonated polymer with dehydrochlorinated PVC samples as intermediates. Two intermediates were formed: (1) partially dehydrochlorinated PVC with long sequences of conjugated double bonds and (2) the product of the partial dehydrochlorination of PVC and the nucleophilic substitution of chlorine by hydroxyl groups. The IR spectra showed that the dehydrochlorinated samples were heterogeneous materials, showing different proportions of elimination products, hydroxyl substitution, and partial oxidation. Samples dehydrochlorinated with poly(ethylene glycol) with a molecular weight of 400 g/mol for 24 h and 15 min showed the highest sulfonation yield, which was related to the sulfonation mechanism occurring predominantly because of the presence of hydroxyl groups in a mixture of vinyl alcohol and vinyl chloride units. The sulfonation was confirmed by the presence of a medium‐intensity band at 1180 cm−1, assigned to sulfonic groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Microscopic surface and bulk morphology of semicrystalline poly(dimethylsiloxane)–polyester copolymers
Authors: Abduallah A. B. E. , Mallon P. E.
Published: October 2009

In this study, two series of semicrystalline poly(dimethylsiloxane) (PDMS)–polyester segmented copolymers with various PDMS contents were synthesized. One series was based on polybutylene adipate (PBA) as the polyester segment and the other was based on a polybutylene cyclohexanedicarboxylate ester (PBCH) segment. The copolymers were characterized using 1H‐nuclear magnetic resonance, size exclusion chromatography, dynamic mechanical analyses, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The microscopic surface morphology and the microscopic bulk morphology were investigated using atomic force microscopy (AFM) and transmission electron microscopy, respectively. The effects of the polyester type and the PDMS content on the crystallinity degree as well as the copolymer surface and bulk morphology at room temperature were investigated for each series. DSC and WAXD results showed the ability of the copolymers to crystallize, to various degrees, depending on the polyester type and the PDMS content. The results showed that the PDMS content had a greater influence on the crystallinity degree in the PDMS‐s‐PBCH (cycloaliphatic) copolymer series than in the PDMS‐s‐PBA (aliphatic) copolymer series. In the copolymers with a low PDMS content, the AFM images showed spherulitic crystal morphology and evidence of PDMS nanodomains in between the crystal lamellae of the ester phase on the copolymer surface. A heterogeneous distribution of the PDMS domains was also observed for these copolymers in the bulk morphology as a result of this segregation between the polyester lamellae. All the copolymers, in both series, showed microphase separation as a result of the incompatibility between the PDMS segment and the polyester segment. Three types of surfaces and bulk morphologies were observed: spherical microdomains of PDMS in a matrix of polyester, bicontinuous double‐diamond type morphology, and spherical microdomains of polyester in a matrix of PDMS as the PDMS content increases. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Modeling the effect of the curing conversion on the dynamic viscosity of epoxy resins cured by an anhydride curing agent
Authors: Teyssandier F. , Ivanković M. , Love B. J.
Published: October 2009

Published curing profiles of epoxy resins mixed with an anhydride curing agent and subsequently crosslinked were reanalyzed with a modified sigmoidal model to describe the dynamic viscosity accompanying resin curing. The sigmoidal analysis yielded two kinetic parameters, one relating to the induction time required to observe meaningful viscosity changes and one relating to the rate of viscosity rise in the rapidly polymerizing zone. Both of these kinetic factors decreased with increasing polymerization temperature. The analysis also led to the interpretation of the upper limit in viscosity in the model that correlated with a higher network density at higher temperatures. The initial viscosity was fixed in our model. The sigmoidal analysis led to a closer representation of the dynamic viscosity data than the Williams–Landel–Ferry (WLF)‐based analysis presented with the original data sets and, although from a more semiempirical basis, might be both easier and more adaptable for incorporating into other flow models. As a final observation, the induction time identified by the log–sigmoidal model correlated closely with the gelation time identified with a modified‐WLF‐based model by Ivankovic et al. (J Appl Polym Sci 2003, 90, 3012); this suggested a similar activation energy threshold for curing advancement. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Fire‐retardant copolymer of acrylonitrile with O,O‐diethyl‐O‐allyl thiophosphate
Authors: Ren Yuanlin , Cheng Bowen , Xu Lin , Jiang Aibing , Lu Youcai
Published: October 2009

A novel halogen‐free flame retardant, O,O‐diethyl‐O‐allyl thiophosphate (DATP), which simultaneously contained phosphorus and sulfur, was synthesized through a simple method. The structure of DATP was characterized by Fourier transform infrared spectroscopy, 1H‐NMR, and mass spectroscopy. The flame‐retardant copolymer was obtained by the free‐radical copolymerization of DATP with acrylonitrile. The flammability and thermal degradation characteristics of the copolymer were assayed by limiting oxygen index measurement, thermogravimetric analysis, and differential scanning calorimetry. The results show that the incorporation of a small percentage of DATP into the copolymer had a significant effect on the retarding combustion of the copolymer, with the limiting oxygen index of the copolymer reaching 28.5% and the char yield being 68.63 wt % at 554°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Surface treatment of plasticized poly(vinyl chloride) to prevent plasticizer migration
Authors: Reddy N. Narayana , Mohan Y. Murali , Varaprasad K. , Ravindra S. , Vimala K. , Raju K. Mohana
Published: October 2009

In this investigation, plasticized poly(vinyl chloride) (PVC) was treated with poly(azido acrylate)s to prevent plasticizer migration. This was achieved by modification of PVC sheets with poly(azido acrylate)s in a dichloromethane solution followed by irradiation under UV light. The surface‐modified PVC sheets with poly (azido acrylate)s were characterized with Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The migration of the plasticizer was prevented to a large extent from modified PVC in comparison with unmodified PVC. The amount of plasticizer migration with respect to the irradiation time, incubation time, and number of dipping times was evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Catalyzed chain extension of poly(butylene adipate) and poly(butylene succinate) with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline)
Authors: Huang Chao Qun , Luo Si Yang , Xu Shao Yi , Zhao Jing Bo , Jiang Sheng Ling , Yang Wan Tai
Published: October 2009

Low‐molecular‐weight HOOC‐terminated poly(butylene adipate) prepolymer (PrePBA) and poly(butylene succinate) prepolymer (PrePBS) were synthesized through melt‐condensation polymerization from adipic acid or succinic acid with butanediol. The catalyzed chain extension of these prepolymers was carried out at 180–220°C with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) as a chain extender and p‐toluenesulfonic acid (p‐TSA) as a catalyst. Higher molecular weight polyesters were obtained from the catalyzed chain extension than from the noncatalyzed one. However, an improperly high amount of p‐TSA and a high temperature caused branching or a crosslinking reaction. Under optimal conditions, chain‐extended poly(butylene adipate) (PBA) with a number‐average molecular weight up to 29,600 and poly(butylene succinate) (PBS) with an intrinsic viscosity of 0.82 dL/g were synthesized. The chain‐extended polyesters were characterized by IR spectroscopy, 1H‐NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray scattering, and tensile testing. DSC, wide‐angle X‐ray scattering, and thermogravimetric analysis characterization showed that the chain‐extended PBA and PBS had lower melting temperatures and crystallinities and slower crystallization rates and were less thermally stable than PrePBA and PrePBS. This deterioration of their properties was not harmful enough to impair their thermal processing properties and should not prevent them from being used as biodegradable thermoplastics. The tensile strength of the chain‐extended PBS was about 31.05 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Surfactant‐dispersed carbon black in polyimide nanocomposites: Spectroscopic monitoring of the dispersion state in the polymer matrix
Authors: Romyen Natthakarn , Thongyai Supakanok , Praserthdam Piyasan
Published: October 2009

The effects of an anionic surfactant on the dispersion of carbon black (CB) for the purpose of forming conducting composite films were examined with ultraviolet–visible (UV–vis) absorption spectroscopy. To obtain a good dispersion and size reduction of aggregated CB in a polymer matrix, sodium dodecyl sulfate (SDS), used as a surfactant, was introduced into a CB suspension. A set of concentrations with various ratios of CB to SDS (ranging from 1 : 0.4 to 1 : 10) was established before mixing with poly(amic acid) (PAA), a precursor of pyromellitic dianhydride and oxydianiline, was performed. The CB/PAA solution mixtures were submerged under an ultrasonic bath for several hours, then cast onto dry plate glasses, and finally subjected to thermal imidization to produce CB/polyimide (PI) nanocomposite films with various CB weight fractions ranging from 0.025 to 0.50 wt %. A method for evaluating the absorbance at 500 nm of the CB/PI nanocomposite films was established. The absorbance of CB/PI nanocomposite samples of various thicknesses was also normalized to get rid of the effects of the different thicknesses. UV–vis spectra showed that the minimum weight ratio of CB to SDS in the nanocomposite films that achieved well‐dispersed CB and still had transparent properties was 1 : 2.0. Transmission electron microscopy demonstrated that CB was dispersed homogeneously in the PI matrix, and the size of the aggregated CB was affected by the amount of the surfactant. The dielectric properties of the nanocomposite films without the surfactant increased by approximately 2 orders of magnitude with an increasing mass weight fraction of CB and decreased when the surfactant was added. The surfactant also reduced the tensile strength of the CB/PI nanocomposites when the CB/SDS ratio was higher than 1 : 2.0. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Molecularly imprinted polypyrrole prepared by electrodeposition for the selective recognition of tryptophan enantiomers
Authors: Kong Yong , Zhao Wei , Yao Shiping , Xu Juan , Wang Wenchang , Chen Zhidong
Published: October 2009

Herein we report the electrosynthesis of polypyrrole with L‐tryptophan (L‐Trp) as a template to prepare molecularly imprinted polymers (MIPs). Overoxidized polypyrrole films with cavities complementary to the template were used for the enantioselective detection of L‐Trp and D‐tryptophan (D‐Trp). Important parameters, such as the electropolymerization potential, overoxidization potential and time, thickness of the polypyrrole films, and scanning rate of the stripping voltammetric experiments, were varied to achieve an optimum sensor response. We found that L‐Trp was inserted about 2 times higher into the imprinted polymer film than D‐Trp. Also, in this study, an electrochemical quartz crystal microbalance technique was used to investigate the performance of overoxidized polypyrrole films. The enantioselectivity of the MIPs was attributed to the cavities in the imprinted films, which were complementary to the target molecules, both in shape and in positioning of the functional groups. The results also suggest the feasibility of preparing MIPs by electropolymerization for the enantioselective recognition of other amino acid enantiomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Silver‐nanoparticle‐loaded chitosan lactate films with fair antibacterial properties
Authors: Tankhiwale Rasika , Bajpai S. K.
Published: October 2009

Food quality and safety are major concerns in the food industry. Antimicrobial packaging can be considered an emerging technology that could have a significant impact on life and food safety. Antimicrobial agents in food packaging can control the microbial population and target specific microorganisms to provide greater safety and higher quality products. In this work, a lactic acid grafted chitosan film was synthesized. Silver nanoparticles were loaded into the chitosan lactate (CL) film by equilibration in a silver nitrate solution, which was followed by citrate reduction. The presence of silver nanoparticles was confirmed with transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis of the film. The silver‐nanoparticle‐loaded CL film was investigated for its antimicrobial properties against Escherichia coli. This newly developed material showed strong antibacterial properties and thus has potential for use as an antibacterial food‐packaging material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of nanoscale azo pigment yellow 13/poly(styrene–maleic acid) composite dispersions via free‐radical precipitation polymerization
Authors: Fu Shaohai , Xu Changhai
Published: October 2009

Nanoscale azo pigment yellow 13 (PY13) was coated by poly(styrene–maleic acid) (PSMA) with a free‐radical precipitation polymerization, followed by the preparation of the dispersion. The effects of the PSMA structure on the particle size and centrifugal stability were investigated. The experimental results revealed that the particle size was large, and the stability of the PY13/PSMA dispersions was high when the molar ratio of the feeding maleic acid to styrene, the weight ratio of the feeding initiator to monomer, and the weight ratio of the feeding monomer to pigment were about 1.0, 0.6, and 20%, respectively. Fourier transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy indicated that PY13 was coated by PSMA. The PY13/PSMA dispersion was stable in the pH range 5.6–10.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Tribological behavior of poly(ether ether ketone) composites filled with potassium titanate whiskers sliding in different media
Authors: Wang Huai‐Yuan , Lu Xiao‐Hua , Shi Yi‐Jun , Feng Xin
Published: October 2009

The friction and wear properties of poly (ether ether ketone) (PEEK) composites filled with potassium titanate whiskers (PTWs) under alkali, water, and dry conditions were investigated. The wear mechanisms in different lubrication situations were studied on the basis of examinations of the worn and counterpart surfaces with scanning electron microscopy and optical microscopy. The results showed that PTWs could obviously increase the wear resistance and reduce the friction coefficient of the PEEK composites under dry sliding conditions. Only when the PTW content was greater than 35 wt % did the wear resistance and friction coefficient deteriorate. Sliding in water caused increases in the wear rate and friction coefficient of the PEEK composites, and the PTW‐filled PEEK composites showed the highest friction coefficient and wear rate under this lubrication condition. On the contrary, sliding in an alkaline solution, the PTW‐filled PEEK composites showed the lowest friction coefficient and almost the same level of wear resistance as that found under the dry condition. Furrows and abrasive wear were the main mechanisms for the PTW‐filled PEEK composites sliding in water. The transfer onto the counterpart rings was significantly hindered with sliding under water and alkali conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Novel observations on kinetics of nonisothermal crystallization in fly ash filled isotactic‐polypropylene composites
Authors: Nath Dilip Chandra Deb , Bandyopadhyay Sri , Yu Aibing , Blackburn Darryl , White Chris
Published: October 2009

A study on nonisothermal crystallization kinetics in fly ash (FA) filled isotactic‐polypropylene (PP) composites has revealed some interesting phenomena. Composites made by injection moulding of PP with 0, 20, 45, and 60 wt % of FA were nonisothermally studied using differential scanning calorimetry at cooling rates 10°C, 15°C, and 20°C per min from a melt temperature of 200°C cooled to −30 °C. Whilst neat PP showed a mono modal α crystalline phase‐ only structure, presence of FA led to bimodal thermographs revealing partial transcrystallisation of α into β, to maximum 14%. The onset and peak crystallization temperatures of all samples decreased by ∼ 3°C with each 5°C/min increase in cooling rate. Parameters such as crystal growth rate, dimensions, and activation energy were determined using a series of established models. The Avrami graphs showed that contrary to the published data, there are two sets of straight lines (a) with a lower slope at low cooling rate and (b) with a distinctly higher slope for high cooling rate. Activation energy of the materials reached a maximum at 45% FA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010