bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conversion of food industrial wastes into bioplastics with municipal activated sludge
Authors: Yu Peter H. , Chua Hong , Huang Phoeby Ai‐Ling 
Published: March 2011

AbstractPlastics have become an integral part of our contemporary life because of many desirable properties including durability and resistance to degradation. However, these non‐degradable, petrochemicals‐derived plastics accumulate in the environment at a rate of 25 million tons per year. Recently there is an interest in the development of a class of microbially produced bioplastics, e.g., polyhydroxyalkanoates (PHAs) which retain the desired physical and chemical properties of conventional synthetic plastics. Broader usage of biodegradable plastics in packaging and disposable products as a solution to the environmental problem would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. In this paper, the microbial production of PHAs by activated sludge utilizing food industrial wastes is reported. The melting points of the products as well as the co‐polymer composition of the products investigated by GC and NMR were compared. By use of activated sludge to convert the carbon source into PHAs not only environment‐friendly bioplastics are produce, but also part of the problem of the disposal of municipal activated sludge is solved. The selection of food industrial waste as carbon resource can also further reduce the cost of production of PHAs.
Dynamic mechanical behaviour of styrene/butadiene copolymers and their blends
Authors: Rek Vesna , Grgurić Tamara H. , Jelčić Želimir , Hace Drago 
Published: March 2011

AbstractThe dynamic mechanical behaviour of high impact polystyrene (PS‐HI), styrene/butadiene/styrene block copolymer (SBS) and PS‐HI + SBS blends were investigated. Dynamic mechanical analysis (DMA) was performed in the temperature range −100°C to 100°C. The primary viscoelastic functions were determined. The copolymers PS‐HI and SBS as well as PS‐HI+SBS blends were investigated in creep‐fatigue regime and relaxation at temperatures 25, 30, 35, 40 and 45°C. Dynamic mechanical behavior of PS‐HI, SBS and PS‐HI + SBS blends depends on the copolymer and blends composition, the hard phase content, time and temperature. With the decrement of the hard phase PS concentration, the loss tangent of the soft phase increases while the loss tangent of the hard phase and the storage modulus decrease. All samples have a single Tg of the hard phase and a single Tg of the soft phase. The glass transition temperatures decrease as the content of the PS phase decreases. At the constant load the creep values increase and those of creep modulus decrease over a period of time, for all examined samples. These effects are more pronounced in samples with lower content of hard phase and at higher temperatures. The time‐temperature correspondence principle was applied to create master curves for the reference temperature 25°C for the creep modulus of PS‐HI, SBS and PS‐HI + SBS blends on a time scale far outside of the range measured by DMA experiments. These results enable us to predict the useful life of our copolymers and their blends in a wide range of time and temperature.
A novel crystalline structure ‐ poly(tetrafluoroethylene) spherulitic crystal and its crystallization kinetics
Authors: Wang Xiao Qun , Han Jie Cai , Du Shan Yi 
Published: March 2011

AbstractSpherulitic crystals of Poly(tetrafluoroethylene) (PTFE), for the first time, are observed in a kind of PTFE composite, and are verified by polarized optic microscopy (POM). Differential scanning calorimetry (DSC) is used to study the isothermal crystallization kinetics of PTFE matrix at different temperatures. The result shows that Avrami parameter is near 3, which may be elucidated that PTFE crystallizes three‐dimensionally from preexisting nuclei. The result is in accordance with scanning electric microscopy (SEM) and POM observation of the crystalline morphology of PTFE. Compared with the rate of one‐dimension crystallization, the rate of three‐dimension crystallization is lower. So the three‐dimension crystallization is easier to control than the one‐dimension crystallization of PTFE.
Thermal stabilization of polypyromellitimide films
Authors: Martsinkevich A. A. , Prokopchuk N. R. , Krutko E. T. 
Published: March 2011

AbstractThe paper is devoted to the modification of the polyimide based on pyromellitic dianhydride and 4,4'‐diaminodiphenyloxide with phosphoric and boric anhydrides. It is demonstrated that, due to the use of phosphorus‐ and boron‐containing polyamidoacid compositions for casting the polyimide films, one can significantly increase their heat resistance without substantial expenditures while, at the same time, preserving the film‐forming ability and mechanical properties of the polyimide.
Severe persistent bone marrow failure following therapy with 2‐chlorodeoxyadenosine for relapsing juvenile xanthogranuloma of the brain
Authors: Yamada Kayo , Yasui Masahiro , Sawada Akihisa , Inoue Masami , Nakayama Masahiro , Kawa Keisei 
Published: March 2011

Abstract2‐Chlorodeoxyadenosine (2‐CdA) has been successfully used in children to treat refractory Langerhans cell histiocytosis and juvenile xanthogranuloma (JXG) as salvage therapy. Although 2‐CdA is generally well‐tolerated, with temporary myelosuppression as the primary dose‐limiting toxicity, prolonged myelosuppressive, and immunosuppressive effects have been reported. We describe an adolescent patient with refractory multiple central nervous system JXG, with the lesion size markedly reduced after treatment with 2‐CdA. However, severe transfusion‐dependent bone marrow failure developed after five courses of 2‐CdA. He underwent successful bone marrow transplantation from his HLA compatible sister with reduced intensity conditioning. Pediatr Blood Cancer 2012; 58: 300–302. © 2011 Wiley Periodicals, Inc.
Synthetic aliphatic biodegradable poly(butylene succinate)/clay nanocomposite foams with high blowing ratio and their physical characteristics
Authors: Lim Sang‐Kyun , Lee Jung‐Joon , Jang Suk‐Goo , Lee Seok‐In , Lee Kwang‐Hee , Choi Hyoung Jin , Chin In‐Joo 
Published: March 2011

AbstractPoly(butylene succinate) (PBS)/organoclay nanocomposites were prepared by both solution blending and melt mixing methods. In addition, nanocomposites of PBS/organoclay were also prepared by a two‐step process where the solution blended mixture is subsequently compounded in the melt state using a torque rheometer (SOAM method). We then investigated thermal and mechanical properties of the PBS/organoclay nanocomposite at first and determined an optimum organoclay content for the preparation of nanocomposite foams. All PBS/organoclay nanocomposite foams are found to possess closed spherical‐shaped cells without any rupture when examined by an optical microscopy. The blowing ratio also increased with the increase in the blowing temperature and time, with the maximum blowing ratio of 19. Furthermore, the addition of a small amount of organoclay is found to allow the cell size to follow Gaussian distribution. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
The nanostructure and dewetting of block copolymer thin films annealed in different neutral solvents
Authors: Ningrum Eva Oktavia , Lin Wei‐Ting , Lo Chieh‐Tsung 
Published: March 2011

AbstractThe morphology of polystyrene‐b‐poly(2‐vinyl pyridine) thin films annealed under various neutral solvents was investigated. The morphological transition depends on the vapor pressure of the solvent, the quantity of the solvent in the film, and annealing time. We introduced the volume fraction of solvent in a film (Q) to correlate these factors to the morphology. At low Q, the amount of solvent that penetrates into the film is limited and it cannot induce enough chain mobility. Thus, thin film shows short stripes or a worm‐like structure. At high Q, the great diffusion of solvent into the film facilitates polymer mobility, leading to an ordered structure. Our results also suggested that the dewetting mechanism of thin film depends on Q. At low Q, dewetting develops via the nucleation and growth. At high Q, the condensation of solvent on the surface removes some polymer and dewetting is dominated by spinodal mechanism. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Crystallization behavior of biodegradable poly(L‐lactide)/multiwalled carbon nanotubes nanocomposites from the amorphous state
Authors: Zhao Yuanyuan , Qiu Zhaobin , Yan Shouke , Yang Wantai 
Published: March 2011

AbstractCrystallization behavior of biodegradable poly(L‐lactide) (PLLA) and its nanocomposites at different carboxyl‐functionalized multiwalled carbon nanotubes (f‐MWNTs) contents from the amorphous state was studied in detail in this work. For the isothermal cold crystallization, the presence of f‐MWNTs enhances the isothermal cold crystallization of PLLA in the nanocomposites compared with that of neat PLLA at the same crystallization temperature; moreover, the overall cold crystallization rate of PLLA increases with increasing the f‐MWNTs content in the PLLA matrix while the crystallization mechanism does not change. For the nonisothermal crystallization, the f‐MWNTs also accelerate the crystallization process of PLLA. In addition, the activation energies of nonisothermal cold crystallization process were calculated using both the Kissinger and Friedman methods. The cold crystallization activation energies of PLLA are higher in the nanocomposites than in neat PLLA, indicating that the addition of f‐MWNTs into the PLLA matrix acts as a physical hindrance to retard crystallization. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Nonisothermal melt‐crystallization behavior of calcium phosphate/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) nanocomposite microspheres
Authors: Duan Bin , Wang Min , Zhou Wen‐You , Cheung Wai‐Lam 
Published: March 2011

AbstractMicrospheres consisting of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) polymer matrix and calcium phosphate (Ca‐P) nanoparticles were made using the solid‐in‐oil‐in‐water (S/O/W) emulsion solvent evaporation technique. Amorphous Ca‐P nanoparticles with the calcium to phosphate ratio of 1.5 were relatively well distributed in microspheres. The nonisothermal crystallization behavior of Ca‐P/PHBV nanocomposite with different Ca‐P contents (0–20%) was studied through differential scanning calorimetry using different cooling rates. During nonisothermal crystallization, the presence of Ca‐P nanoparticles resulted in an increase in crystallization rate and the nucleation activity of the nanocomposite also increased with increasing Ca‐P content. Various models were applied to investigate nonisothermal crystallization kinetics. All approaches, except for the Ozawa model, could successfully describe the nonisothermal crystallization behavior of PHBV and Ca‐P/PHBV nanocomposite. The effective activation energy for nonisothermal crystallization was calculated using the differential isoconversional method proposed by Friedman. The morphology of PHBV spherulites in nanocomposite was also studied using polarized optical microscopy. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Synthesis and photochemical properties of novel pentamethylated norbornadiene containing polyimides
Authors: Oueslati Ahmed , Ben Romdhane Hatem , Martin Vincent , Schiets Fréderic , Mercier Régis , Chaâbouni Refaât 
Published: March 2011

AbstractA novel pentamethylated norbornadiene (NBD) based dianhydride, α,α′‐bis‐(3,4,5,6,7‐pentamethylcyclopenta‐2,4‐dienyl)meta‐xylene‐1,2‐dianhydride (3), was prepared from α,α′‐bis‐(pentamethylcyclopentadienyl)meta‐xylene (1) and acetylene dicarboxylic acid. The bis‐adduct formed via Diels–Alder reaction afforded tetra‐acid (2), which was chemically cyclodehydrated to lead the targeted dianhydride (3). New polyimides containing NBD moieties in the main chain were prepared from the dianhydride monomer (3) and various aromatic diamines. The chemical structure of the polymers was confirmed by both 1H and 13C NMR analysis. Their Molecular weights were also measured by SEC. All of these polyimides are soluble at room temperature in common organic solvents, such as chloroform, dichloromethane, THF, DMSO, DMF, and NMP, and show good thermal stabilities. The photochemical isomerization of the NBD into quadricyclane (QC) was investigated by UV/vis spectrophotometry from polymer films using visible sunlight as irradiation source. It was found that the kinetic rate of the conversion NBD‐QC which proceeded smoothly is a first kinetic order. The stored energies released by the transformation of QC groups into NBD ones of the irradiated polymer films were also evaluated by DSC measurement and were found to be around 90 kJ mol−1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Anionic polymerization of MMA and renewable methylene butyrolactones by resorbable potassium salts
Authors: Hu Yangjian , Gustafson Laura O. , Zhu Hongping , Chen Eugene Y.‐X. 
Published: March 2011

AbstractThree resorbable potassium salts of hydride (K[H]), enolate Me2CC(OiPr)OK (K[E]), and allyl K[1,3‐(SiMe3)2C3H3] (K[A]) have been investigated for controlled anionic polymerization of methyl methacrylate (MMA) and its cyclic analogs, naturally renewable methylene butyrolactones including α‐methylene‐γ‐butyrolactone (MBL) and γ‐methyl‐α‐methylene‐γ‐butyrolactone (MMBL). When used alone at ambient temperature in toluene, these salts exhibit no (K[H]) to low (K[A]) to modest (K[E]) polymerization activity. Mixing of K[H] and Al(C6F5)3 leads to the formation of an “ate” complex, K+[HAl(C6F5)3]−, which has been structurally characterized by X‐ray diffraction; this complex has a high polymerization activity producing atactic PMMA, but addition of another equiv of Al(C6F5)3 further enhances both the rate and the efficiency of the polymerization, now producing syndiotactic PMMA with a narrow molecular weight (MW) distribution of 1.04. The K[H]/2Al(C6F5)3 system also exhibits high activity for polymerization of (M)MBL. In sharp contrast, addition of Al(C6F5)3 to K[A] shuts down the polymerization at various temperatures. The most active, controlled, and syndioselective polymerization system in this series is K[E]/2Al(C6F5)3. Accordingly, the polymerization control and kinetics of this most effective system have been examined in more detail. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Ring‐opening polymerization of ε‐caprolactone catalyzed by Yttrium trisphenolate in the presence of 1,2‐propanediol. Do both primary and secondary hydroxyl groups initiate polymerization?
Authors: Ling Jun , Liu Jinzhi , Shen Zhiquan , Hogen‐Esch Thieo E. 
Published: March 2011

AbstractAlthough the ring‐opening polymerization (ROP) of ε‐caprolactone (CL) in toluene at 100 °C can be initiated by yttrium trisphenolate (Y(OC6H5)3), in the presence of 1,2‐propanediol (PD) the ROP gives much better, that is, controlled polymerizations. In this case, the molecular weights (MWs) are controlled by the CL/PD molar ratios with primary and secondary hydroxyl groups both initiating the ROP and the MW distributions are narrow. The chain transfers between the active yttrium alkoxides and the residual hydroxyl groups on the PD and/or the chain ends appear to be much faster than chain propagation, consistent with the living character of the ROP. Computational studies support these facile reactions with estimated activation free energies in the 3.0–4.5 kcal/mol range compared with about 25–30 kcal/mol for the polymerization. Intramolecular transfer within the PD is predicted to be negligible having a calculated activation energy of 19 kcal /mol. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Altered architecture of substrate binding region defines the unique specificity of UDP‐GalNAc 4‐epimerases
Authors: Bhatt Veer S. , Guo Chu‐yueh , Guan Wanyi , Zhao Guohui , Yi Wen , Liu Zhi‐jie , Wang Peng G. 
Published: March 2011

AbstractUDP‐hexose 4‐epimerases play a pivotal role in lipopolysaccharide (LPS) biosynthesis and Leloir pathway. These epimerases are classified into three groups based on whether they recognize nonacetylated UDP‐hexoses (Group 1), both N‐acetylated and nonacetylated UDP‐hexoses (Group 2) or only N‐acetylated UDP‐hexoses (Group 3). Although the catalysis has been investigated extensively, yet a definitive model rationalizing the substrate specificity of all the three groups on a common platform is largely lacking. In this work, we present the crystal structure of WbgU, a novel UDP‐hexose 4‐epimerase that belongs to the Group 3. WbgU is involved in biosynthetic pathway of the unusual glycan 2‐deoxy‐L‐altruronic acid that is found in the LPS of the pathogen Pleisomonas shigelloides. A model that defines its substrate specificity is proposed on the basis of the active site architecture. Representatives from all the three groups are then compared to rationalize their substrate specificity. This investigation reveals that the Group 3 active site architecture is markedly different from the “conserved scaffold” of the Group 1 and the Group 2 epimerases and highlights the interactions potentially responsible for the origin of specificity of the Group 3 epimerases toward N‐acetylated hexoses. This study provides a platform for further engineering of the UDP‐hexose 4‐epimerases, leads to a deeper understanding of the LPS biosynthesis and carbohydrate recognition by proteins. It may also have implications in development of novel antibiotics and more economic synthesis of UDP‐GalNAc and downstream products such as carbohydrate based vaccines.
Avoiding disastrous couplings in SU(5) orientifolds
Authors: Anastasopoulos P. , Leontaris G.K. , Richter R. , Schellekens A.N. 
Published: March 2011

AbstractThis proceeding is based on the paper 1010.5188 [hep‐th] where we discuss SU(5) Grand Unified Theories in the context of orientifold compactifications. Specifically, we investigate three D‐brane stack realizations of the Georgi‐Glashow model and analyze them with respect to their Yukawa couplings. We show that most/all phenomenological problems that appear in two stack models can be resolved in three stack models. We exemplify with globally consistent Georgi‐Glashow models based on RCFT that these D‐brane quivers can be indeed embedded in a global setting.
Influence of hydrogen on electrical and optical properties of ZnO films
Authors: Kim Y.H. , Karazhanov S. Zh. , Kim W.M. 
Published: March 2011

AbstractElectrical and optical properties of H doped ZnO films have been studied experimentally for different H concentrations before and after annealing, as well as theoretically by first‐principles calculations. It is found that electrical resistivity of the H doped ZnO increases when increasing the substrate temperature in the range 25–300 °C. Carrier concentration and mobility measured by Hall method in as‐grown samples are larger than those of annealed ones. The short‐wavelength edge of the transmission spectrum of annealed ZnO is found to shift toward lower energies compared to as‐grown samples. The band gap estimated from the measured transmission spectra of as grown ZnO increases with increasing H concentration, thus demonstrating the Burstein–Moss effect. However, it decreases in samples annealed at 300 °C showing suppression of the Burstein–Moss effect. Possible defect models explaining the reason for the suppression are discussed. The results can be explained by formation of H2 molecules in annealed ZnO.
Effect of electrical field on crystallization and ferroelectric properties of Ge:Sb:Te films
Authors: Gervacio Arciniega J. J. , Prokhorov E. , Espinoza Beltran F. J. , Trapaga Martınez L. G. , Gonzalez‐Hernandez J. 
Published: March 2011

AbstractIn this work impedance spectroscopy has been used to investigate of the NaCl type‐hexagonal transition in stoichiometric Ge2Sb2Te5 and in non‐stoichiometric (Ge24Sb15Te61) films. The temperature dependence of capacitance in all films shows an abrupt change (about 4‐6 times) at the temperature corresponding to the end of the NaCl type‐hexagonal transition. Additional, impedance measurements were carried out in films which have been crystallized with an external DC electric field. Comparing the results in the films crystallized with and without the external electric field, it is observed that in films crystallized with an external electric field, the capacitance increases during the NaCl type‐hexagonal transition for about 9‐15 times and that the piezoresponse force microscopy measurements have shown ferroelectric domains in the NaCl type phase. External electrical field changes significantly the onset of amorphous‐NaCl type crystallization temperature which could be related with an increase in atomic diffusion, promoting the growth of the crystalline phase. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Glass‐formation and phase transformation parameters of chalcogenide glasses from the GeSe2–GeTe–ZnTe system
Authors: Aljihmani Lilia , Vassilev Venceslav , Hristova‐Vasileva Temenuga 
Published: March 2011

AbstractNew chalcogenide glasses from the GeSe2‐GeTe‐ZnTe system are synthesized. The glass‐forming region in it is outlined and some main physicochemical properties (temperatures of glass transition, crystallization and melting; glass transition activation energy; enthalpy and entropy alternation of the crystallization process) of the obtained glasses are determined. A correlation between the investigated physicochemical properties and the composition of the obtained glasses is established. The observed extreme points in these dependencies for the (GeSe2)72(GeTe)18(ZnTe)10 composition are interpreted in relation to the structural changes (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferromagnetic properties with reentrant spin‐glass behavior in amorphous EuZrO3 thin film
Authors: Zong Yanhua , Fujita Koji , Akamatsu Hirofumi , Murai Shunsuke , Tanaka Katsuhisa 
Published: March 2011

AbstractWe report on the preparation, structure, and magnetic properties of amorphous EuZrO3, an amorphous ferromagnetic oxide. The samples were prepared in the form of thin film through a pulsed‐laser‐deposition method and their structure was confirmed to be amorphous by X‐ray diffraction and high‐resolution transmission electron microscope observation. Amorphous EuZrO3 thin films exhibit a ferromagnetic transition and reenter into a spin glass phase at a lower temperature, while crystalline EuZrO3 is an antiferromagnet as reported previously. The difference in magnetic properties between amorphous and crystalline EuZrO3 is suggested to arise from the difference in their structures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of helical induced anisotropy in amorphous ribbons for sensor applications
Authors: García Alfonso , Maganto Fernando , Tremps Enrique , Ramírez Puerto , Moron Carlos 
Published: March 2011

AbstractAmorphous samples with helical induced anisotropy show magnetization processes that can be controlled by applying a longitudinal magnetic field simultaneously with an alternating current flowing through the sample. By varying the current amplitude and the phase difference between current and applied field, a wide range of coercivity and susceptibility values can be achieved.This work shows that the apparent coercive field and the susceptibility can be controlled in amorphous ribbons with helical anisotropy. These characteristics make these samples very suitable for their application as sensor cores, magnetic amplifiers, variable reluctance transformer cores, etc (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)