bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of talc on the mechanical and thermal properties of polylactide
Authors: Yu Fengmei , Liu Tao , Zhao Xiuli , Yu Xuejiang , Lu Ai , Wang Jianhua 
Published: February 2012

AbstractPolylactide (PLA) composites with various talc content were prepared by melt extrusion. The thermal, dynamic mechanical, tensile and flexural properties, and fracture surface morphologies of neat PLA and PLA/talc composites were investigated and compared. The results showed that talc had significant nucleation effect and the cold crystallization temperature of PLA decreased with talc concentration. The thermal degradation and heat distortion temperature of PLA were slightly enhanced by compounding with talc. Talc showed significant reinforcing and toughening effects on PLA, the tensile strength, flexural strength and modulus increased with talc content ranging from 0 to 24.3 wt %. The results of tensile test showed that the elongation at break increased with talc content up to 18.1 wt % with obvious changes in fracture behavior, changing from brittle to ductile, when talc content increased to 24.3%, samples failed in a brittle manner with low elongation at break. The fracture surface morphologies showed that the talc layers were partially delaminated, aligned along the flow direction, and uniformly dispersed in the PLA matrix. The results obtained by SEM and FTIR confirmed that the interfacial adhesion between talc and PLA matrix was good. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Dynamic mechanical properties of curaua composites
Authors: Ornaghi Heitor Luiz , da Silva Humberto Sartori Pompeo , Zattera Ademir José , Amico Sandro Campos 
Published: February 2012

AbstractIn this study, we aimed to evaluate the characteristics of curaua composites using dynamic mechanical analysis. Curaua composites with distinct fiber volume fractions (11–38%) were studied, and their storage and loss moduli were found to increase with reinforcement content. On the other hand, the activation energy of the relaxation process in the glass‐transition region decreased with the curaua content; this conclusion was corroborated by the elastic chain concentration results. The Cole–Cole plots became flattened as the curaua content increased; this was indicative of a more homogeneous system, and the tan δ peak height and peak width at half‐height decreased. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of cobalt‐60 γ radiation on the physical and chemical properties of poly(ethylene terephthalate) polymer
Authors: Siddhartha  , Aarya Suveda , Dev Kapil , Shakir Mohd , Ahmed Bashir , Wahab M. A. 
Published: February 2012

AbstractThe structural, optical, and morphological properties of Co60 γ irradiation on poly(ethylene terephthalate) polymer samples were studied with X‐ray diffraction (XRD), ultraviolet–visible spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy. The diffraction pattern of virgin sample showed that the polymer was semicrystalline in nature. However, because of irradiation, the crystallinity decreased up to a dose level of 110 kGy and increased up to 300 kGy. The crystallite size, strain, and dislocation were calculated from the XRD data, and the crystallite size decreased from 291.07 to 346.90 Å. The absorption edge shifted from 315 to 330 nm, and the band gap of the samples decreased from 3.79 to 3.66 eV. The SEM micrographs showed radial bulging along with inhomogeneous liner exfoliation, and also, a rocky shape pattern with different sizes was observed. A significant change was found in the Raman spectra of the γ‐irradiated polymer at the highest dose. The results of the structural, optical, and morphological studies show recovery characteristics at the highest dose level of 300 kGy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Properties of styrene butadiene rubber/recycled acrylonitrile‐butadiene rubber (SBR/NBRr) blends: Effect of the addition of trans‐polyoctylene rubber
Authors: Noriman N. Z. , Ismail H. , Rashid A. A. 
Published: February 2012

AbstractThis study investigated polymer blends based on different ratios of styrene butadiene rubber (SBR) and recycled acrylonitrile butadiene rubber (NBRr) with and without trans‐polyoctylene rubber (TOR) as a compatibilizer. Five compositions of SBR/NBRr/TOR were prepared; 95/5/5, 85/15/5, 75/25/5, 65/35/5, and 50/50/5. Rheological characteristics, tensile and physical properties, and the morphological behavior of compatibilized and uncompatibilized SBR/NBRr blends were determined. The rheological characteristics indicated that compatibilized SBR/NBRr blends had a shorter cure time (t90) than uncompatibilized SBR/NBRr blends. The compatibilized SBR/NBRr blends showed lower minimum torque (ML) when compared with as uncompatibilized SBR/NBRr blends, indicating that compatibilization improved the processability of the blends. However, the maximum torque (MH) of compatibilized SBR/NBRr blends was higher than that of uncompatibilized SBR/NBRr blends. The incorporation of TOR improved the tensile strength, tensile modulus (M100), hardness, and crosslinked density of compatibilized SBR/NBRr blends. However, the elongations at break (Eb) and resilience of compatibilized SBR/NBRr blends were lower as compared to uncompatibilized SBR/NBRr blends. Scanning electron microscopy of the tensile fractured surfaces demonstrated that the addition of TOR in SBR/NBRr blends improved the adhesion between NBRr and the SBR matrix, thus improving the compatibility of SBR/NBRr blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Production and characterization of hybrid BEH‐PPV/PEO conjugated polymer nanofibers by forcespinning™
Authors: Padron Simon , Patlan Richard , Gutierrez Jose , Santos Nestor , Eubanks Thomas , Lozano Karen 
Published: February 2012

AbstractThe fabrication of hybrid poly(2,5‐bis(2′‐ethyl‐hexyl)‐1,4‐phenylenevinylene) (BEH‐PPV) and polyethylene oxide (PEO) nanofibers is reported. Nanofibers were created using a novel production method that uses centrifugal rather than electrostatic force to produce nanofibers. The nanofiber production method exhibits high yield production of nanofibers enabling mass‐production capabilities. Thermo‐physical characterization and X‐ray diffraction of bulk PEO and BEH‐PPV was conducted, and the results are compared with the produced hybrid nanofibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Functional terpolymers containing vinylphosphonic acid: The synthesis and characterization of poly(vinylphosphonic acid‐co‐styrene‐co‐maleic anhydride)
Authors: Kavlak Serap , Güner Ali , Rzayev Zakir M. O. 
Published: February 2012

AbstractNovel functional temperature‐sensitive amphiphilic P‐containing polymers were synthesized by complex‐radical ternary polymerization of vinylphosphonic acid (VPA), styrene (S), and maleic anhydride (MA). Charge transfer complexes (CTCs), complex‐formation constants (Kc) between acceptor and donor monomer systems and the complexed monomer reactivity ratios were investigated by 1H‐NMR analysis. Contrary to theoretical predictions, the VPA…S complex is more active as compared to MA…S complex in the ternary system since VPA monomer can form the CTC both with S monomer and strong H‐bonded complex with MA monomer. The terpolymer compositions, characterizations, and structure–property relationships of a series of poly(VPA‐co‐S‐co‐MA)s were investigated by GPC, FTIR, Raman, 1H‐NMR, 13C‐NMR, DEPT‐135, 31P‐NMR, TGA‐DSC, DMA, XRD, viscometry, and titration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effective aminolytic depolymerization of poly(ethylene terephthalate) waste and synthesis of bisoxazoline therefrom
Authors: Shah Rikhil V. , Shukla Sanjeev R. 
Published: February 2012

AbstractAminolytic depolymerization of postconsumer poly(ethylene terephthalate) (PET) bottle waste with 2‐amino‐2‐methyl‐1‐propanol and 1‐amino‐2‐propanol under atmospheric condition was investigated in the presence of catalysts zinc acetate or sodium acetate. The virtual products obtained in pure form were, respectively, bis(1‐hydroxy‐2‐methylpropan‐2‐yl)terephthalamide and bis(2‐hydroxypropyl)terephthalamide. The latter was taken for further studies because of its higher yield and subjected to cyclization using thionyl chloride under low‐temperature conditions to get 1,4‐bis(5‐methyl‐4,5‐dihydrooxazol‐2‐yl)benzene, which is used as chain extender in polyester and nylon compositions and as a crosslinking agent in powder paint compositions. The products obtained from depolymerization were characterized by TLC, melting point, IR spectroscopy, 1H‐NMR, 13C‐NMR, and DSC. We have shown that it is possible to synthesize new utility products by recycling of PET waste. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigation of the curing process of spray polyurea elastomer by FTIR, DSC, and DMA
Authors: Zhou Qing , Cao Li , Li Qing , Yao Yalin , Ouyang Zhaofei , Su Zhiqiang , Chen Xiaonong 
Published: February 2012

AbstractThe curing process of a typically formulated spray polyurea elastomer (SPUA) system has been thoroughly investigated with the help of a combined analysis of Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The evolvement of the microstructure and mechanical responses of the SPUA system during the curing process have been described in detail. The experimental results indicated that the fast curing property of SPUA, which mainly based on the reaction between the primary amine groups and the isocyanate groups, led to the formation of the unstable hard segments in the interphase. After the tack‐free time, the residual isocyanate groups continued to react with the rest of the secondary amine groups of the chain extenders for several hours and caused the increase of the molecular weight of the hard segment in SPUA. Furthermore, during the curing process, the “disordered” hydrogen bond formed by one CO and one nearby NH (secondary amine) reconstructed to “ordered” bond, which contributed to the increase of the content of the hard segment and ultimately, improved the mechanical properties of the SPUA system greatly. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of electrostatic polarity and the types of electrical charging on electrospinning behavior
Authors: Wu Chang‐Mou , Chiou Hau‐Geng , Lin Siang‐Ling , Lin Jian‐Min 
Published: February 2012

AbstractIn this study, we examined the effect of applied electrostatic voltages and the types of electrical charging on jet movement, fiber productivity, fiber diameter and deposited configuration by two inverse polarity systems, termed as spinneret and collector charging systems. Jet movement parameters such as Taylor cone, straight jet length, whipping angle, and pitch of whipping loop are examined and compared. The results show that the electronegative collector charging system or the electropositive spinneret charging system is superior to their contrastive system in terms of smaller fiber diameter, compact fiber deposited configuration, and higher fiber productivity. Optimal applied voltage found was 25 kV for electronegative collector charging system and 30 kV for electropositive spinneret charging system and resulted in finest fiber diameter (209 nm for electronegative collector charging system and 247 nm for electropositive spinneret charging system). Polyvinyl acetate solution jet is easier to be ejected, stretched, and accelerated under electropositive charging. The spinning jet with electropositive charges can be achieved either in the spinneret charging system by using electropositive charger or in the collector charging system by using electronegative charger. This finding is an important guideline for the designing of electrospinning device. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Overview on the production of biodiesel from Jatropha curcas L. by using heterogenous catalysts
Authors: Yusuf Nik N.A.N. , Kamarudin Siti K. , Yaakob Zahira 
Published: February 2012

AbstractJatropha curcas oil (JCO) is considered a future feedstock for biodiesel production because it is easily grown in harsh environments and is a non‐edible crop that is not in demand as a food source. Three basic methods are used to produce biodiesel from oils/fats, namely the base‐catalyzed transesterification, acid‐catalyzed transesterification, and enzymatic catalysis. However, heterogeneous transesterification using a solid catalyst rather than a liquid acid or base catalyst is a more environmentally responsible way to utilize crude Jatropha oil for biodiesel production. The use of a heterogeneous catalyst also avoids neutralization and washing steps, thereby leading to a simpler and more efficient process. This paper presents an overview of the production of biodiesel from Jatropha Curcas Linnaeus (JCL) using a heterogeneous catalyst. This review also includes the current economic trend of biofuel production particularly on the production of biodiesel. Different types of conventional and advanced methods like ultrasound, microwave, membrane reactor, supercritical methanol, etc., using several types of heterogeneous catalysts like calcium oxide (CaO), sulfanated zirconia alumina (SZA) and others in the JCO biodiesel transesterification process are discussed in detail. The system design of the transesterification process via process simulation and optimization are also presented. Finally, the persistent challenges facing this process are discussed. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd
On the formation of the double helix between adenine single strands at acidic pH from synchrotron radiation circular dichroism experiments
Authors: Holm Anne I. S. , Munksgaard Nielsen Lisbeth , Vrønning Hoffmann Søren , Brøndsted Nielsen Steen 
Published: February 2012

AbstractHere, we present synchrotron radiation circular dichroism spectra for a series of DNA adenine strands, (dA)n, n = 2–10, 15, at acidic pH. Reference spectra of a protonated single strand, (dAH+)n, and a protonated double helix, (dAH+)n:(dAH+)n, are provided in the wavelength region from 175 to 330 nm. The largest spectral difference between single and double strands is in the vacuum ultraviolet, where a band changes sign. This new spectral feature that characterizes double helix formation may be useful for analytical purposes but also for shedding light on the underlying complexation mechanism. Furthermore, we find that a minimum of eight or nine bases in a strand is needed for two (dAH+)n strands to form a duplex. This is a relatively high number as compared with guanine quadruplex and cytosine i‐motif formation, which is likely linked to the significant Coulomb repulsion between the all‐protonated bases. Finally, spectra recorded as a function of time after sample preparation indicates that the equilibrium is slowly reached, in certain cases taking an hour or more. © 2012 Wiley Periodicals, Inc. Biopolymers 97:550–557, 2012.
Thermo‐responsive non‐woven scaffolds for “smart” 3D cell culture
Authors: Rossouw Claire L. , Chetty Avashnee , Moolman Francis Sean , Birkholtz Lyn‐Marie , Hoppe Heinrich , Mancama Dalu T. 
Published: February 2012

AbstractThe thermo‐responsive polymer poly(N‐isopropylacrylamide) has received widespread attention for its in vitro application in the non‐invasive, non‐destructive release of adherent cells on two dimensional surfaces. In this study, 3D non‐woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (PET), and nylon that had been grafted with PNIPAAm were tested for their ability to support the proliferation and subsequent thermal release of HC04 and HepG2 hepatocytes. Hepatocyte viability and proliferation were estimated using the Alamar Blue assay and Hoechst 33258 total DNA quantification. The assays revealed that the pure and grafted non‐woven scaffolds maintained the hepatocytes within the matrix and promoted 3D proliferation comparable to that of the commercially available Algimatrix™ alginate scaffold. Albumin production and selected cytochrome P450 genes expression was found to be superior in cells growing on pure and grafted non‐woven PP scaffolds as compared to cells grown as a 2D monolayer. Two scaffolds, namely, PP‐g‐PNIPAAm‐A and PP‐g‐PNIPAAm‐B were identified as having far superior thermal release capabilities; releasing the majority of the cells from the matrices within 2 h. This is the first report for the development of 3D non‐woven, thermo‐responsive scaffolds able to release cells from the matrix without the use of any enzymatic assistance or scaffold degradation. Biotechnol. Bioeng. 2012; 109:2147–2158. © 2012 Wiley Periodicals, Inc.
A model for cellulase production from Trichoderma reesei in an airlift reactor
Authors: Bannari Rachid , Bannari Abdelfettah , Vermette Patrick , Proulx Pierre 
Published: February 2012

AbstractA mathematical model for cellulase production by Trichoderma reesei RUT‐C30 grown in a cellulose medium with lactose as fed batch in an airlift reactor is proposed. To describe adequately the mass transfer between the air bubbles and the broth, it uses computational fluid dynamics (CFD) including multiphase Eulerian–Eulerian formulation, with a detailed description of the bubble size distribution through the use of the population balance model (PBM) and the class method (CM). The kinetics of the biomass growth is further coupled to the fluid flow conditions using partial differential equations for all the species involved, providing detailed information of important reactor conditions such as the distribution of oxygen, cellulose, and the shear stress within the reactor over the entire period of fermentation. Predicted results agree well with the available overall measurements for a typical fed‐batch operation and detailed profiles of the predicted concentration fields are discussed from an engineering viewpoint. Biotechnol. Bioeng. 2012; 109:2025–2038. © 2012 Wiley Periodicals, Inc.
Metabolic engineering of Lactobacillus casei for production of UDP‐N‐acetylglucosamine
Authors: Rodríguez‐Díaz Jesús , Rubio‐del‐Campo Antonio , Yebra María J. 
Published: February 2012

AbstractUDP‐sugars are used as glycosyl donors in many enzymatic glycosylation processes. In bacteria UDP‐N‐acetylglucosamine (UDP‐GlcNAc) is synthesized from fructose‐6‐phosphate by four successive reactions catalyzed by three enzymes: Glucosamine‐6‐phosphate synthase (GlmS), phosphoglucosamine mutase (GlmM), and the bi‐functional enzyme glucosamine‐1‐phosphate acetyltransferase/N‐acetylglucosamine‐1‐phosphate uridyltransferase (GlmU). In this work several metabolic engineering strategies, aimed to increment UDP‐GlcNAc biosynthesis, were applied in the probiotic bacterium Lactobacillus casei strain BL23. This strain does not produce exopolysaccharides, therefore it could be a suitable host for the production of oligosaccharides. The genes glmS, glmM, and glmU coding for GlmS, GlmM, and GlmU activities in L. casei BL23, respectively, were identified, cloned and shown to be functional by homologous over‐expression. The recombinant L. casei strain over‐expressing simultaneously the genes glmM and glmS showed a 3.47 times increase in GlmS activity and 6.43 times increase in GlmM activity with respect to the control strain. Remarkably, these incremented activities resulted in about fourfold increase of the UDP‐GlcNAc pool. In L. casei BL23 wild type strain transcriptional analyses showed that glmM and glmU are constitutively transcribed. By contrast, glmS transcription is down‐regulated with a 21‐fold decrease of glmS mRNA in cells cultured with N‐acetylglucosamine as the sole carbon source compared to cells cultured with glucose. Our results revealed for the first time that GlmS, GlmM, and GlmU are responsible for UDP‐GlcNAc biosynthesis in lactobacilli. Biotechnol. Bioeng. 2012; 109:1704–1712. © 2012 Wiley Periodicals, Inc.
The surgical significance of residual mucosal abnormalities in rectal cancer following neoadjuvant chemoradiotherapy
Authors: Smith F M , Chang K H , Sheahan K , Hyland J , O'Connell P R , Winter D C 
Published: February 2012

Abstract

Background
Local excision of rectal cancer after neoadjuvant chemoradiotherapy (CRT) has been proposed as an alternative to radical surgery in selected patients. However, little is known about the significance of the morphological and histological features of residual tumour.

Methods
Patients who had undergone CRT at the authors' institution between 1997 and 2010 were identified. Multiple features were assessed as putative markers of pathological response. These included: gross residual disease, diameter of residual mucosal abnormalities, tumour differentiation, presence of lymphovascular/perineural invasion and lymph node ratio.

Results
Data from 220 of 276 patients were suitable for analysis. Diameter of residual mucosal abnormalities correlated strongly with pathological tumour category after CRT (ypT) (P &lt; 0·001). Forty of 42 tumours downstaged to ypT0/1 had residual mucosal abnormalities of 2·99 cm or less after CRT. Importantly, 19 of 31 patients with a complete pathological response had evidence of a residual mucosal abnormality consistent with an incomplete clinical response. The ypT category was associated with both pathological node status after CRT (P &lt; 0·001) and lymph node ratio (P &lt; 0·001). Positive nodes were found in only one of 42 patients downstaged to ypT0/1. The risk of nodal metastases was associated with poor differentiation (P = 0·027) and lymphovascular invasion (P &lt; 0·001).

Conclusion
In this series, the majority of patients with a complete pathological response did not have a complete clinical response. In tumours downstaged to ypT0/1 after CRT, residual mucosal abnormalities were predominantly small and had a 2 per cent risk of positive nodes, thus potentially facilitating transanal excision. The presence of adverse histological characteristics risk stratified tumours for nodal metastases.
Outlier detection of air temperature series data using probabilistic finite state automata‐based algorithm
Authors: Shen Jun , Yang Minhua , Zou Bin , Wan Neng , Liao Yufang 
Published: February 2012

AbstractThis article proposes a probability finite state automata‐based algorithm (PFSAA) for detecting outliers of air temperature series data caused by sensor errors. This algorithm first divides the training samples of air temperature series data into subclusters that will be further used to build finite state automata by splitting and combining techniques. Then, it creates a dynamic transition matrix of PFSA based on probability theories. Finally, the outliers of the remaining test samples are detected by PFSAA. The proposed algorithm is quantitatively validated by the reference data and a traditional backpropagation neural net model. © 2012 Wiley Periodicals, Inc. Complexity, 2012
Evaluating nonlinear variability of mental fatigue behavioral indices during long‐term attentive task
Authors: Azarnoosh Mahdi , Nasrabadi Ali Motie , Mohammadi Mohammad Reza , Firoozabadi Mohammad 
Published: February 2012

AbstractThis study investigates the behavioral indices of attention. A simple repetitive attentive task that resulted in mental fatigue was used consecutively in four trials. In the first step, reaction time and error responses were recorded to evaluate differences among trials. During the task, subjects showed different responses to stimulations. In the second part, to recognize the strategies, multiple clustering methods such as k‐means and fuzzy c‐means were performed in which behavioral indices and nonlinear features were used. In the last section, mental behavior was identified as a result of the chaotic properties of variations in reaction time. Therefore, the Lyapunov exponent of reaction times was evaluated. Results revealed that behavioral indices could distinguish attention from the occurrence of mental fatigue in trials. In addition, the three strategies used by subjects during the test protocol were assessed. Finally, variation of indices extracted from nonlinear analysis, that is, decrease in degree of chaotic behavior determined the transition from attention to mental fatigue. © 2012 Wiley Periodicals, Inc. Complexity, 2012