Highly crystalline and oriented high‐strength poly(ethylene terephthalate) fibers by using low molecular weight polymer

High‐strength poly(ethylene terephthalate) (PET) fibers were obtained using low molecular weight (LMW) polymervia horizontal isothermal bath (hIB), followed by postdrawing process. We investigated the unique formations of different precursors, which differentiated in its molecular orientation and crystalline structures from traditional high‐speed spinning PET fibers. Sharp increase in crystallinity was observed after drawing process even though the fibers showed almost no any crystallinity before the drawing. Properties of as‐spun and drawn hIB and control filaments at different process conditions were compared. As would be expected, performances of resulted treated undrawn and drawn fibers have dramatically improved with developing unique morphologies. Tenacities more than 8 g/d for as‐spun and 10 g/d for drawn treated fibers after just drawn at 1.279 draw ratio were observed. These performances are considerably higher than that of control fibers. An explanation of structural development of high‐strength fibers using LMW polymer spun with hIB is proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42747.     

Synthesis and polymerizations of novel bisphosphonate‐containing methacrylates derived from alkyl α‐hydroxymethacrylates

The synthesis and polymerizations of four novel bisphosphonate‐containing monomers are reported. The monomers were synthesized from reaction of ethyl and tert‐butyl α‐bromomethacrylates with 3,3‐bis(diethoxyphosphoryl)propanoic acid or with tetraethyl 4‐hydroxybutane‐1,1‐diyldiphosphonate. Their thermal bulk polymerizations, photopolymerizations and copolymerizations with poly(ethylene glycol) methyl ether methacrylate were investigated. The homopolymerizations resulted in polymers with values of 25 000–83 000 g mol^?1; the copolymerizations yielded soluble polymers with 22–34% incorporation of the new monomers; the photopolymerizations gave some structure–reactivity correlation; and one of the homopolymers, upon hydrolysis of its bisphosphonate groups, could interact with hydroxyapatite. © 2013 Society of Chemical Industry     

Collagen-based hydrogel films as drug-delivery devices with antimicrobial properties

Collagen (coll)-containing hydrogel films were prepared by mixing degraded collagen with monomers such as acrylamide (AAm), and 2-hydroxy ethylmethacrylate (HEMA) before the polymerization/cross-linking of composites as p(coll-co-AAm), and p(coll-co-HEMA), respectively. These materials were used as drug-delivery devices for potential wound dressing materials by loading and releasing of model drugs such as gallic acid (GA) and naproxen (NP). A linear release profile was obtained up to 32-h release from GA-loaded p(coll-co-AAm) interpenetrating polymeric networks films, and 36-h linear release profile of NP for p(coll-co-HEMA). Furthermore, metal nanoparticles such as Ag and Cu prepared within these hydrogel films offered antimicrobial characteristic against known common bacteria such as Escherichia coli, Bacillus subtilis, and Staphylococcus aureus.     

An optimum feature extraction method for texture classification

Texture can be defined as a local statistical pattern of texture primitives in observer’s domain of interest. Texture classification aims to assign texture labels to unknown textures, according to training samples and classification rules. In this paper a novel method, which is an intelligent system for texture classification is introduced. It used a combination of genetic algorithm, discrete wavelet transform and neural network for optimum feature extraction from texture images. An algorithm called the intelligent system, which processes the pattern recognition approximation, is developed. We tested the proposed method with several texture images. The overall success rate is about 95%.     

Forecasting of entropy production due to buoyant convection using support vector machines (SVM) in a partially cooled square cross-sectional room

Forecasting of entropy generation of laminar natural convection in a partially cooled square cross-sectional room has been performed using support vector machines (SVM). The two-dimensional room was modeled as floor heating story with a window. Values of temperature and velocities were obtained by solving governing equations of natural convection with finite difference technique and using these values entropy generation was calculated with its definition. Forecasting of entropy generation due to fluid friction irreversibility (FFI) and heat transfer irreversibility (HTI) were made with known values for unknown parameters using SVM. Thus, calculation time was extremely reduced and values were obtained even for non-convergence cases. It was observed that the SVM was a strong method to predict the entropy generation without computational fluid dynamic analysis for all cases.     

Effect of high valency cations on the (BiPb)2Sr2Ca3Cu4O12+δ compounds

We have produced the (BiPb)₂V _x Sr₂Ca₃Cu_4−y Ti _y O_12+δ compounds by a melt-quenching method. For two different sintering times (185 and 192 hours), the effects of vanadium adding and Ti doping on the structure have been investigated by electrical resistance, scanning electron micrographs (SEM), XRD patterns and magnetic hysteresis loop measurements. It has been found that the high-T _c superconducting phase, (2223), is formed in the samples annealed at 845 ^○C for 185 and 192 h, with concentration x=0.2 and y=0.05. However, with increasing Ti doping the (2223) phase gradually transforms into the (2212) phase. The hysteresis loop areas decrease with increasing Ti concentration and sintering time. Our data have indicated that the critical current, J _c , decreases with increasing magnetic field.     

Synthesis and photopolymerization of novel,highly reactive phosphonated-urea-methacrylates for dental materials

An urea methacrylate (1) and two phosphonated methacrylates (2–3) were synthesized from 2-isocyanatoethyl methacrylate (IEM) and benzyl amine (1), diethyl aminomethylphosphonate (2) and diethyl amino(phenyl)methylphosphonate (3). Their photopolymerization rates are notably higher than commercial monomers, despite the presence of only one double bond. Their polymerization rates follow the order 1 ～ 2 > 3 ～ triethylene glycol dimethacrylate (TEGDMA) > 2-hydroxyethyl methacrylate (HEMA). A tendency toward high crosslinking density during thermal bulk polymerizations, low oxygen sensitivity and high conversions with benzophenone during photopolymerization indicated the importance of hydrogen abstraction/chain transfer reactions. It was found that the addition of the monomers to HEMA significantly increased its polymerization rate, proving their utility as replacements for TEGDMA as reactive diluents for 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propyloxy) phenyl] propane (Bis-GMA). Copolymer systems containing 2 and 3 showed improved T_g values compared to Bis-GMA/TEGDMA systems.     

Retrieving relevant time‐course experiments: a study on Arabidopsis microarrays

Understanding time‐course regulation of genes in response to a stimulus is a major concern in current systems biology. The problem is usually approached by computational methods to model the gene behaviour or its networked interactions with the others by a set of latent parameters. The model parameters can be estimated through a meta‐analysis of available data obtained from other relevant experiments. The key question here is how to find the relevant experiments which are potentially useful in analysing current data. In this study, the authors address this problem in the context of time‐course gene expression experiments from an information retrieval perspective. To this end, they introduce a computational framework that takes a time‐course experiment as a query and reports a list of relevant experiments retrieved from a given repository. These retrieved experiments can then be used to associate the environmental factors of query experiment with the findings previously reported. The model is tested using a set of time‐course Arabidopsis microarrays. The experimental results show that relevant experiments can be successfully retrieved based on content similarity.Inspec keywords: botany, lab‐on‐a‐chip, genetics, bioinformatics, information retrieval, data mining, data analysis, associative processingOther keywords: relevant time‐course experiment retrieval, time‐course Arabidopsis microarray, time‐course gene regulation, stimulus response, systems biology, computational method, gene behaviour model, gene networked interaction, latent parameter, model parameter estimation, meta‐analysis, data analysis, time‐course gene expression experiment, information retrieval, computational framework, time‐course experiment query, relevant experiment list, repository, environmental factor, query experiment, experimental content similarity     

Physical, antibacterial and antioxidant properties of chitosan films incorporated with thyme oil for potential wound healing applications

Chitosan films incorporated with thyme oil for potential applications of wound dressing were successfully prepared by solvent casting method. The water vapor permeability, oxygen transmission rate, and mechanical properties of the films were determined. Surface and cross-section morphologies and the film thicknesses were determined by Scanning Electron Microscopy (SEM). Fourier transform infrared (FT-IR) spectroscopy was conducted to determine functional group interactions between the chitosan and thyme oil. Thermal behaviors of the films were analyzed by Thermal Gravimetry (TGA) and Differential Scanning Calorimetry (DSC). In addition, the antimicrobial and the antioxidant activities of the films were investigated. The antimicrobial test was carried by agar diffusion method and the growth inhibition effects of the films including different amount of thyme oil were tested on the gram negative microorganisms of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and a gram positive microorganism of Staphylococcus aureus. The minimum thyme oil concentration in chitosan films showing the antimicrobial activity on all microorganisms used in the study was found as 1.2 % (v/v). In addition, this concentration showed the highest antioxidant activity due to mainly the carvacrol in thyme oil. Water vapor permeability and oxygen transmission rate of the films slightly increased, however, mechanical properties decreased with thyme oil incorporation. The results revealed that the thyme oil has a good potential to be incorporated into chitosan to make antibacterial and permeable films for wound healing applications.