bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on Determination of Chemical Oxygen Demand in Water with Ion Chromatography
Authors: Zhang Zhong‐Hai , Ding Hong‐Chun , Fang Yan‐Ju , Xian Yue‐Zhong , Jin Li‐Tong 
Published: February 2007

AbstractA new method for determining chemical oxygen demand (COD) value in water using ion chromatography coupled with nano TiO2‐K2S2O8 co‐existing system was described. The photocatalytic oxidation system and nano TiO2‐K2S2O8 co‐existing system could degrade the organic compounds in water. All sulfur‐containing species in the reactive solution were eventually transformed to sulfate which could be determined by conductivity detector in ion chromatography. The change of conductivity of sulfate was proportional to COD value. The optimal experimental conditions and the mechanism of the detection were discussed. The application range was 10.0–300.0 mg·L−1 and the lowest limit of detection was 3.5 mg·L−1. It was considered that the value obtained could be reliably correlated with the COD value obtained using the conventional methods.
Nucleophilic Substitution on Porphyrin Ring: Synthesis of 2‐(2‐Hydroxynaphthyl)‐5,10,15,20‐tetraphenylporphyrin
Authors: Chen Zhang‐Ping , Hu Qin , Zhai Bao‐Ping , Jiang Zhong‐Xing , Qin Wei 
Published: February 2007

AbstractThe reactions of 2‐nitro‐5,10,15,20‐tetraphenylporphyrin (1) and its Ni (II) (2), Cu (II) (3), Zn (II) (4) complexes with sodium 2‐naphthoxide have been investigated in different solvents for preparing 2‐substituted porphyrins. 2‐(2‐Hydroxynaphthyl)‐5,10,15,20‐tetraphenyl porphyrin (5) and its Ni (II) (6), Cu (II) (7), Zn (II) (8) complexes were obtained in 72%, 78%, 81% and 65% yields in 2‐naphthol at 150 °C respectively. The same products were also obtained in other protic solvents such as diglycol and diglycol monomethyl ether. When the reactions proceeded in aprotic solvent DMF at 150 °C, besides 5 (70%), 6 (34%), 7 (54%) and 8 (50%), the corresponding 2‐(2‐naphythoxy)‐5, 10,15,20‐tetraphenylporphyrin (9), and its Ni (II) (10), Cu (II) (11), Zn (II) (12) complexes were also obtained in minor, 40%, 18% and 2% yields respectively, but only 5, 6, 7, 8 were found at room temperature in DMF or DMSO. These reactions are much faster than those of 1–4 with sodium phenoxide. The formation of C‐coupling products 5–8 was proposed via SRN1 mechanism.
Aspects of the Population Dynamics of Corophium curvispinum G. O. Sars in Reed Belts along a Trophic Gradient in Lake Balaton (Hungary)
Authors: Muskó Ilona B. , Lakatos Gyula , Bíró Péter , Zólyomi Zsolt 
Published: February 2007

AbstractThe population structure, abundance (ind m−2), biomass and reproduction of Corophium curvispinum, an important element of the littoral fauna, have been studied at four sampling stations on the northern shoreline of Lake Balaton (Keszthely Bay, Szigliget Bay, Bozsai Bay and Paloznak Bay) three times a year (spring, summer and autumn) in Phragmites growing period from May 1991 to October 1993 and in summer 1994. The sampling stations represent the trophic gradient of the lake.The environmental parameters (Chlorophyll‐a content of the plankton and of the reed periphyton, and suspended solid content of the water) were significantly higher (ANOVA) in the western basin (Keszthely and Szigliget bays) than in the eastern basin (Bozsai and Paloznak bays). However, the population parameters (length of the animals, percentage of juveniles, length of ovigerous females, percentage of ovigerous females and fecundity) did not differ significantly between the two basins. Both the abundance and biomass were higher in the middle than in the westernmost and easternmost bays but the difference is not significant.The ovigerous females were significantly bigger in spring than in summer and autumn. The egg number per female was also significantly greater in spring than in summer and autumn. The length of ovigerous females and the fecundity in summer did not differ significantly from those of autumn data.There is a significant positive correlation (Spearman rank correlation) between both abundance and biomass and the above environmental parameters. The length of ovigerous females and the fecundity were inversely correlated with the plankton Chlorophyll‐a concentrations.The abundance of C. curvispinum in the reed belt of Lake Balaton is greater than in several parts of the Dnieper and Volga. However, it is much lower than in the Don, Oka, Danube and Rhine rivers.
Evolution of gastrulation in the ray‐finned (actinopterygian) fishes
Authors: Cooper Mark S. , Virta Valerie C. 
Published: February 2007

AbstractSometime before or during the early Mesozoic era, new lineages of actinopterygian (ray‐finned) fishes radically transformed their mode of gastrulation. During this evolutionary transformation, yolky endoderm was a hotspot for ontogenetic change. As holoblastic cleavage patterns were modified into meroblastic cleavage patterns, major changes in cell identity specification occurred within the mesendodermal marginal zone, as well as in the superficial epithelium of the embryo. These cellular identity changes resulted in the appearance of two novel extra‐embryonic tissues within the embryos of teleostean fishes: the enveloping layer (EVL) and the yolk syncytial layer (YSL). The generation of these extra‐embryonic tissues prompted major morphogenetic changes within the Organizer Region. As these evolutionary changes occurred, the outermost cell layer of the Organizer (the Organizer Epithelium) was apparently retained as a signaling center necessary for the establishment of left–right embryonic asymmetry in the embryo. Conserved and derived features of Organizer morphogenesis and gastrulation within ancient lineages of ray‐finned fishes provide important insights into how the genetically encoded cell behaviors of early morphogenesis can be altered during the course of evolution. In particular, a highly divergent form of actinopterygian gastrulation, which is found in the annual fishes of South America, demonstrates that no aspect of vertebrate gastrulation is inherently immutable to evolutionary change. J. Exp. Zool. (Mol. Dev. Evol.) 308B:591–608, 2007. © 2007 Wiley‐Liss, Inc.
Ultrastructural studies of midgut epithelium formation in Lepisma saccharina L. (Insecta, Zygentoma)
Authors: Rost‐Roszkowska M. M. , Piłka M. , Szymska R. , Klag J. 
Published: February 2007

AbstractAt the end of embryogenesis of Lepisma saccharina L. (Insecta, Zygentoma), when the stomodaeum and proctodaeum are completely formed, the midgut epithelium is replaced by the primary midgut, a yolk mass is surrounded by a cell membrane. Midgut epithelium formation begins in the 1st larval stage. Energids migrate toward the yolk periphery and aggregate just beneath the cell membrane. They are gradually enclosed by cell membrane folds of the primary midgut. Single cells are formed. Succeeding energids join just formed cells. Thus, groups of cells, regenerative cell groups, are formed. Their number gradually increases. The external cells of the regenerative cell groups transform into epithelial cells and their basal regions spread toward the next regenerative cell groups. Epithelial cells of neighboring regenerative cell groups join each other to form the epithelium. At the end of the 2nd larval stage, just before molting, degeneration of newly the formed epithelium begins. Remains of organelles and basal membrane occur between the regenerative cell groups. The new epithelium is formed from the regenerative cell groups, which are now termed stem cells of the midgut epithelium. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
Is There any Relation Between the Solubility of a Polymeric Additive and its Performance as a Pour Point Reducer?
Authors: Mansur Claudia R. E. , Lima Aline F. , Spinelli Luciana S. , González Gaspar , Lucas Elizabete F. 
Published: February 2007

AbstractIn this work, polymeric additives based on poly(ethylene‐co‐vinyl acetate) were chemically modified by inserting different contents of hydrocarbon chains (C14). The performance of the modified copolymers as organic deposition inhibitors (ODI) was evaluated using a model system composed of different types of paraffins by measuring the pour point and viscosity of these systems. The phase behavior of the modified copolymers was evaluated in systems with different solubility parameters in order to correlate the additive's performance as ODI and the esteem solubility parameter of these modified copolymers. The results show that the EVA modified copolymers performed better ODI than those obtained for non‐modified copolymer. However, the molecule must retain a hydrophobic‐lypophobic balance in order to keep its capacity to modify the paraffin crystal. Moreover, copolymers with similar solubility parameters did not present the same pour‐point values, which suggests that the solubility of the additive is important, but is not the only factor that influences the additive performance.
Development of a Method to Evaluate the Performance of Aqueous Polymer Solutions as Drag Reduction Agents in Bench Scale
Authors: Figueiredo Marcos S. , Almeida Lucilla C. , Costa Francileide G. , Clarisse Márcia D. , Lopes Léa , Leal Rafael , Martins André L. , Lucas Elizabete F. 
Published: February 2007

AbstractThis work describes a method to evaluate, in reduced scale, the performance of polymer samples as drag reduction agents in aqueous solutions. To measure the pressure drop in a turbulent regime, a specially adapted capillary viscosimeter was used, with reduced dimensions adapted to produce the desired regime and adequate pressure measurement points. To verify the technique's reliability, samples of polyacrylamide were synthesized with different molar masses, by varying the quantity of the polymerization initiator. The molar masses obtained were determined by size exclusion chromatography (SEC). The efficiency of the polymer as a drag reducer, as expected, increased as the molar mass increased, which validates the use of this method to study the drag reduction properties of polymer materials in aqueous solutions.
Structured Thermoplastic/Thermoset Blends Using Block Copolymers
Authors: Fine Thomas , Pascault Jean‐Pierre 
Published: February 2007

AbstractThermoplastic/thermoset blends have been compatibilized by block copolymers. The thermoplastic is poly(phenylene ether) and the thermoset precursors are a liquid epoxy, diglycidyl ether of bisphenol A (DGEBA) and an aromatic diamine (4,4′ methylene bis [3 chloro 2,6 diethylaniline], MCDEA). The triblock poly(styrene‐ b‐butadiene‐b‐methyl methacrylate), SBM has been chosen because (i) PS blocks interact very favourably with PPE (ii) PMMA blocks remain miscible with the thermoset during the whole curing process, and (iii) PB mid blocks are expected to cover the interface. Morphologies of blends were observed by Transmission Electron Microscopy and phase composition evaluated by Dynamic Mechanical Thermal Analysis. It was observed that the strong repulsion between PPE and PMMA blocks governs the organization of the blend before and during the curing process. During polymerization a purification of the matrix is induced. As expected, a large proportion of block copolymer is at the interface between the matrix and nodules. It was demonstrated that the number of SBM micelles and their degree of dispersion is the main parameter controlling the mechanical properties.
Styrene Suspension Polymerization Using a Stirred Vertical Tubular Reactor
Authors: Nogueira André L. , Machado Ricardo A. F. , Quadri Marintho B. 
Published: February 2007

AbstractSuspension polymerization reactions are commonly carried out in tank reactors designed with low values for the H/D ratio (Height/Diameter). As polymerization reactions are frequently high exothermic, the superficial area of these equipments are not enough high to adequately release the heat generated by the reaction. In this case, additional systems are necessary to provide cooling fluids with sufficiently low temperatures in order to maintain constant the polymerization temperature in the tank reactor. On the other hand, tubular reactors can be considered economically attractive because their high superficial area for heat exchange (high H/D) can improve temperature control and reduce operational costs. The present work uses a vertical tubular reactor to carry out the batch styrene suspension polymerization and evaluate the effects of the reactor and stirring system configuration on the polystyrene PSD (Particle Size Distribution). According to the results, besides a very good temperature control due to the reactor geometry, polystyrene particles with relatively narrow particle size distributions can be successfully produced in a stirred vertical tubular reactor.
Measurement of the Emitted Light Polarization State in Oriented and Non‐Oriented PPV Films
Authors: Alliprandini‐Filho Paulo , Silva R. A. , da Silva George B. , Neto N. M. Barbosa , Cury L. A. , Moreira R. L. , Marlleta Alexandre 
Published: February 2007

AbstractIn this work we report the influence of the molecular orientation on the light emission polarization of poly (p‐phenylene vinylene) (PPV) films. The oriented film was processed via the Langmuir‐Blodgett (LB) technique while the non‐ordered one was processed by casting technique. By means of an ellipsometry experiment, the information about the polarization state of the emitted light was obtained via Stokes parameters and the dissymmetry factor (g). The experiments were carried out at room and low temperature (10 K) and in the phonon‐replicas range at 543 and 633 nm. We have observed a high dependence in the g factor and in the ellipticity of the emission spectra for LB films as function of the spectrum region, i. e., the phonon‐replicas. This effect is attributed to the memory of the circular polarization that is lost by thermal disorder when the emission occurs distant from the zero‐ phonon peak.
Characteristics of Liposomes Prepared by the Modified Reverse‐Phase Evaporation Method: 31P‐NMR and TEM Study
Authors: Pentak Danuta , Sułkowski Wiesław W. , Maślanka Sławomir , Wolińska Agnieszka , Duber Stanisław , Sułkowska Anna 
Published: February 2007

AbstractThe NMR spectroscopy was used to determine a structure and physicochemical properties of liposomes prepared from L‐α‐phosphatidylcholine dipalmitoyl (DPPC) by the modified reverse‐phase evaporation method (mREV). 31P‐NMR study of the liposome in the temperature range from 340K to 350K allowed us to suggest that the single‐bilayered liposome has been obtained. Transmission electron micrographs (TEM) showed that the liposome vesicles, obtained with the use of the modified (mREV) method, were spherical in shape and in majority they were less than 100 nm in diameter.
Biomimetic Particles
Authors: Lincopan Nilton , Rosa Heloísa , Carmona‐Ribeiro Ana M. 
Published: February 2007

AbstractElectrostatically driven bilayer coverage from bilayer fragments onto oppositely charged latex produces a highly homodisperse particulate for biomolecules adsorption. Polystyrene sulfate (PSS) particles were covered with single cationic dioctadecyldimethylammonium bromide (DODAB) bilayers. Biomolecules adsorbed were DNA, bovine serum albumin (BSA), cholera toxin (CT) and a mixture of purified 18 kDa/14 kDa Taenia crassiceps proteins (18/14‐Tcra). Firstly, the DODAB/PSS assembly was characterized at 1 mM NaCl and 5 × 109 PSS particles/mL over a range of DODAB concentrations (0.001 ‐1 mM) by means of dynamic light scattering for particle sizing and zeta‐potential analysis. 0.01 mM DODAB was enough to produce perfectly homodisperse and cationic bilayer‐covered particles. Secondly, under these experimental conditions, BSA, CT, and 18/14‐Tcra adsorbed onto biomimetic bilayer‐covered particles yielding langmuirian isotherms with 1.23 × 1017, 0.82 × 1017, 3.37 × 1017 molecules per m2 at limiting adsorption and affinity constants (K) of 3.17 × 1010, 3.39 × 1010, and 1.75 × 1010 M−1, respectively. For DNA adsorption, isotherms did not attain an adsorption maximum up to 20 micrograms/mL DNA. PSS/DODAB/biomolecule assemblies were also characterized by means of dynamic light scattering and zeta‐potential analysis yielding highly monodisperse particles at and above maximal adsorption. In summary cationic bilayer‐covered particles are a novel, highly organized and, possibly, general support for biomolecules immobilization.
Polyurethanes Elastomers Based on Poly(ε‐caprolactone) Diol: Biodegradation Evaluation
Authors: Kloss Juliana , de Souza Fernanda S. M. , da Silva Edilsa R. , Dionísio Jair Alves , Akcelrud Leni , Zawadzki Sônia Faria 
Published: February 2007

AbstractSumary: Plastics materials are widely used in the manufacturing of many products like bags, packings, electronic components among other applications. Most polymers are extremely durable and this durability cause serious environmental problems because of the large amount of waste discarded mainly in the urban centers. Thus, biodegradable polymers are a potencial way to minimize these problems. Polyurethanes based on poly(ε‐caprolactone) (PCL) as soft segment were prepared taking into account the biodegradable charater of this last compound. The hard segment was built up by reaction between tolylene diisocyanate (TDI) and a chain extender (1,4‐butanediol) or two crosslinking agents (sucrose or glucose). The biodegradation behavior of the polyurethanes was verified using solid and submerged fermentation and using natural conditions under the soil. The analysis indicated that the biodegradation was affected by the PCL segment, hard segment content, intermolecular interations manly H bonds and crosslinking.
Thermal Degradation of Natural Rubber Male Condoms
Authors: Bó Maria Cristina , Lopes Léa , Visconte Leila Lea Yuan , Nunes Regina Célia Reis 
Published: February 2007

AbstractCondoms play an important role in the prevention of human immunodeficiency virus transmission. The prediction of condom shelf life became a high priority for the international and national committees responsible for the standardization of the quality of the product. In this work, two sets of batches of natural rubber condoms from three manufactures were compared to investigate the effect of the total sulphur, in their formulations, on the thermal degradation of the products. One set was manufactured in 1999–2000, and the other was manufactured in 2004–2005. The techniques used were differential scanning calorimetry (DSC) and thermogravimetry (TGA) in different atmospheres, as well as elemental analysis in the determination of the total sulphur present in the condoms. The results show that the profile of the thermal behavior is very similar to all condoms. No clear correlation between the amount of sulphur in the formulations and the thermal behavior of the products was found. This study intended to contribute to the development of a method for predicting shelf life of natural rubber male condoms.
Elastic solutions of displacements for a transversely isotropic full space with inclined planes of symmetry subjected to a point load
Authors: Hu Ting‐Bin , Wang Cheng‐Der , Liao Jyh‐Jong 
Published: February 2007

AbstractThis work presents analytical solutions for displacements caused by three‐dimensional point loads in a transversely isotropic full space, in which transversely isotropic planes are inclined with respect to the horizontal loading surface. In the derivation, the triple Fourier transforms are employed toyield integral expressions of Green's displacement; then, the triple inverse Fourier transforms and residue calculus are performed to integrate the contours. The solutions herein indicate that the displacements are governed by (1) the rotation of the transversely isotropic planes (ϕ), (2) the type and degree of material anisotropy (E/E′, ν/ν′, G/G′), (3) the geometric position (r, φ, ξ) and (4) the types of loading (Px, Py, Pz). The solutions are identical to those of Liao and Wang (Int. J. Numer. Anal. Methods Geomechanics 1998; 22(6):425–447) if the full space is homogeneous and linearly elastic and the transversely isotropic planes are parallel to the horizontal surface. Additionally, a series of parametric study is conducted to demonstrate the presented solutions, and to elucidate the effect of the aforementioned factors on the displacements. The results demonstrate that the displacements in the infinite isotropic/transversely isotropic rocks, subjected to three‐dimensional point loads could be easily determined using the proposed solutions. Also, these solutions could realistically imitate the actual stratum of loading situations in numerous areas of engineering. Copyright © 2007 John Wiley & Sons, Ltd.
Physical properties of Bi‐doped CdTe thin films deposited by cosputtering
Authors: Becerril M. , Vigil‐Galán O. , Contreras‐Puente G. , Sánchez‐Meza E. , Zelaya‐Angel O. 
Published: February 2007

AbstractThe structural, morphological, electrical, and optical properties of CdTe–Bi cosputtered thin films related with composition are presented. The films were grown on Corning glass substrates at room temperature from a CdTe–Bi target. The composition measurements show that the Bi content in the films ranges from x = 0.0 to x = 6.37 at%, depending on the area fraction covered by the Bi piece attached to the CdTe target. The structure of the annealed films was determined from X‐ray diffraction measurements. Two kinds of structures were observed, depending on the Bi content: (1) CdTe polycrystalline films containing a small amount of Bi that is probably incorporated in the Cd and Te sites of the CdTe lattice. (2) Amorphization of the polycrystalline films, with higher Bi content. From the experimental results, we concluded that using this deposition method n/p‐type Bi‐doped CdTe polycrystalline films can be produced with electrical resistivity between 102–103 Ω cm and electron mobility between 101 and 102 cm2 V–1 s–1. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laser‐doping of silicon carbide for p–n junction and LED fabrication
Authors: Bet Sachin , Quick Nathaniel , Kar Aravinda 
Published: February 2007

AbstractThe high melting point and the limited diffusion of impurities in silicon carbide have greatly restricted the use of conventional ion implantation and furnace to incorporate and activate dopants. A laser doping technique overcomes these obstacles for doping silicon carbide and other wide band gap semiconductors. This paper presents the work on fabrication of p–n junction diodes and blue light emitting diodes using laser doping technique. A p–n junction was created by laser doping a silicon carbide wafer with aluminum (p‐type) and nitrogen (n‐type). Optical interferometer profilometer scan showed that there was no damage on the surface post laser doping. Secondary ion mass spectrometry (SIMS) was carried to estimate the dopant concentration and depth. The effects of laser doping on the current–voltage characteristics were studied. The junctions were characterized by capacitance–voltage and electroluminescence measurements. A broad electroluminescence peak was observed around 498.8 nm wavelength, characterizing the p–n junction as a blue light‐emitting diode. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on the local structure and the spin‐Hamiltonian parameters for Cu3+ ions in Al2O3 crystal
Authors: Wei Qun , Yang Zi‐Yuan , Xu Qi‐Ming 
Published: February 2007

AbstractThe relations between the spin‐Hamiltonian (SH) parameters and crystal structure of Al2O3:Cu3+ crystal have been established using the SH theory. On the basis of this, the SH parameters of Al2O3:Cu3+ crystal have been calculated, and the problem of too many adjustable parameters in previous work has been solved. The calculated results are in good agreement with experiment data. This shows that the model we adopted is reasonable. The results show that, when a Cu3+ ion is doped into Al2O3 crystal, it does not occupy Al3+ site accurately, but moves 0.0214 nm along the C3‐axis. The contributions to SH parameters from spin triplet and spin singlet are also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)