bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase-diagram-related problems in thermoelectric materials: Skutterudites as an example
Authors: Shi X. , Zhang W. , Chen L. D. , Uher C. 
Published: June 2008

Abstract
CoSb3 is a very promising thermoelectric semiconductor with narrow gap and good electrical transport properties. It is also a special compound with an intrinsically caged crystal structure. By taking void filling in the intrinsic cages and impurity substitution for Co in the skutterudites as examples, a few phase-diagram-related problems in thermoelectric materials are discussed. The first topic shows that the filling fraction limit for an impurity in the crystal voids could be taken as a phase-diagram-related issue to be solved by first-principles energetic calculations. But the partial void filling also reveals that the structural integrity of a compound with special structure is very sensitive to electron filling and its influence on chemical bonding, which needs further study. This is assumed to be a general problem linking with the group of compounds with special 2-D layered or 3-D caged structures, a focus of current thermoelectric research. The second topic relates to the solid solution problem when mixing CoSb3 with IrSb3 (or RhSb3) to realize new materials with random distribution of Ir or Rh at Co sites. By going through most of the currently state-of-the-art thermoelectric compounds including CoSb3/IrSb3, PbTe/(Ag,Sb)Te2, MgSi2/MgSn2/MgGe2, and ZrNiSn/HfNiSn, it is found that their mixing enthalpies are usually slightly positive, implying the possibility of mixing 2- or 3-similar compounds to realize nanocomposites with low internal strain for promising performance. Related experimental and theoretical issues on nanocomposite thermoelectrics are briefly discussed.
Tropical forest structure and diversity in relation to altitude and disturbance in a Biosphere Reserve in central India
Authors: Sahu P.K. , Sagar R. , Singh J.S. 
Published: June 2008

AbstractQuestions: Is species diversity affected in protected areas where human activities are permitted or tolerated? On plots of a fixed size, does stem density alone predict number of species? Are differences in density related to disturbance and altitude?Location: Achanakmar‐Amarkantak Biosphere Reserve, central India.Methods: 42 sites, each with three replicate 10‐m radius plots, were examined. All trees (≥ 30 cm GBH) in each plot were measured for girth at breast height. α‐diversity, species richness and evenness were calculated for each site. The sites were ordinated by Nonmetric Multidimensional Scaling (NMS) using relative importance values of component species. Correspondence Analysis was used to broadly delineate communities. Anthropogenic disturbances were recorded in terms of percentage of trees lopped, scale of lopping, number of domestic livestock dung piles and foot trails (both livestock and people) for each plot.Results: The NMS analysis exhibited a near linear arrangement of sites with no evidence of discrete vegetation zones. NMS axes were significantly related to altitude and disturbance scores. With increasing elevation, basal area increased but number of species, α‐diversity and its components declined monotonically. The number of species and indices of species diversity were positively associated with tree lopping and also with total disturbance. Number of species was controlled by stem density only in plots not dominated by Shorea robusta.Conclusions: Recent levels of human disturbance are associated with higher species diversity in this biosphere reserve. There is some evidence that stands at all altitudes follow the same successional pattern to dominance by Shorea, a successional pattern that also results in decreased diversity without disturbance.
Land use designation and vegetation community structure in the Adirondack uplands (New York, USA)
Authors: Woodcock T. , Evans C. , Laxson C. , Tucker R. , Allen J. , Mihuc J. , Allen E. , Mihuc T. 
Published: June 2008

AbstractQuestion: Does forest vegetation community structure reflect legislative land use designations?Location: Adirondack Park, New York, USA.Methods: The Adirondack Park, located in northern New York State, is a mixture of public and private lands, with state‐owned Forest Preserve lands comprising ca. 42% of the 2.4 million ha, on which timber harvesting and many other forms of anthropogenic disturbance are prohibited. A survey of vegetation communities was conducted in eighteen upland catchments with differing land use history (managed and Forest Preserve), including overstory, understory, and dead wood (snags and downed woody debris) using randomly placed plots.Results: Mean overstory density and basal area were not significantly different between land uses, although mean overstory tree size was greater in Preserve catchments. Sapling densities were greater in managed catchments, while mean herb/shrub coverage was not affected by land use. Densities of 25% of common species were affected by land use, determined by GIS coverages constructed using an Inverse Distance Weighted estimation procedure. Discriminant Analysis of per‐plot plant community data correctly classified 89% of both managed and Preserve plots.Conclusion: The success of the Discriminant Analysis in classifying land uses based on vegetation communities indicates its potential utility of this method in comparing forest vegetation to a reference condition in this and other areas. The analysis suggests that at least 85 years is required for Adirondack up‐land catchments to recover following harvesting. Uncertainty in classification was related to heterogenous management and disturbance patterns within catchments.
Roadside revegetation with native plants: Experimental seeding and transplanting of stem cuttings
Authors: Mallik Azim U. , Karim M.N. 
Published: June 2008

AbstractQuestions: Can we use local native plants for roadside revegetation? What cultural methods help enhance the process?Location: Trans Canada Highway, Terra Nova National Park, Newfoundland.Objectives: To (1) test stratification requirements for seed ger‐mination, (2) determine if germination, survival and growth of seedlings and stem cuttings of selected plants can be increased by mulching treatments and (3) identify native plants and cultural treatments useful for revegetation.Methods: We tested seed germination of Kalmia angustifoliaIris versicolorJuncus effususEriophorum vaginatum, Clintonia borealis and Cornus canadensis in a greenhouse experiment. We conducted field experiments of roadside revegetation using seeds of K. angustifolia, I. versicolorJ. effusus and E. vaginatum, as well as seedlings of I. versicolor and rooted stem cuttings of Emptrum nigrum and Juniperus communis after hay‐mat mulch and organic matter mulch application.Results: Stratified seeds of K. angustifoliaI. versicolor, J. effusus and E. vaginatum germinated successfully in the greenhouse, whereas C. borealis and C. canadensis seeds did not. Along roadsides, only I. versicolor seeds germinated. Iris versicolor cover increased significantly in organic matter mulch compared to hay‐mat mulch and control. Transplanted I. versicolor seedlings had high survival in all treatments but growth was reduced in organic matter mulch. Survival and growth of stem cuttings of E. nigrum and J. communis were significantly increased on hay‐mat mulch.Application: Rooted stem cuttings of E. nigrum and J. communis planted on hay‐mat mulch can be used as a practical method of roadside revegetation. These shrubs have low structure, are evergreen, and exhibit stress‐tolerance properties, which make them ideal species for roadside revegetation. They are also non‐palatable to wildlife. Roadside ditches can be revegetated by seeds or seedlings of I. versicolor. Robust roots and rhizomes of this plant may provide soil stability and dark green leaves and attractive flowers create aesthetically pleasing vegetation cover.
Numerical characterization of three‐dimensional serpentine micromixers
Authors: Park Jang Min , Kwon Tai Hun 
Published: June 2008

AbstractThree‐dimensional serpentine micromixer (TSM) has been well known to be an attractive design because of its simple fabrication and efficient mixing performance, but its basic characteristics have not been fully investigated notwithstanding several reports in the past. The present article comprehensively investigates flow and mixing characteristics of TSM. Three major mixing mechanisms are identified, namely rotation, lamination, and chaotic advection. The mixing performance of TSM is analyzed and compared in terms of the three mechanisms by means of numerical analysis with three representative types as examples of TSM: (1) serpentine type C; (2) serpentine type L; (3) improved serpentine laminating micromixer. Numerical analysis system based on a finite element method and a colored particle tracking method enables not only flow visualization but also computation of Poincaré section and Lyapunov exponent for a dynamical system analysis of TSM. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Clinical and genetic heterogeneity in patients with mosaic variegated aneuploidy: Delineation of clinical subtypes
Authors: García‐Castillo Herbert , Vásquez‐Velásquez Ana Isabel , Rivera Horacio , Barros‐Núñez Patricio 
Published: June 2008

AbstractMosaic variegated aneuploidy (MVA) is a rare autosomal recessive syndrome related to BUB1B gene mutations and characterized by multiple mosaic aneuploidies, cancer predisposition, and a distinct phenotype. We report on two mildly affected sibs with MVA syndrome but without BUB1B mutation. Both patients exhibited growth retardation, frontal bossing, triangular face and micrognathia but not microcephaly or cancer. Aneuploidies were assessed both in G‐banded metaphases from lymphocyte cultures and in interphase nuclei from buccal cells by FISH. Screening of 23 exons and intron–exon boundaries of BUB1B was also carried out. These patients were then compared with other 19 MVA patients screened for BUB1B mutations. Around one half of the cultured lymphocytes from our patients had aneuploidies ranging from nullisomies to heptasomies; the most frequent abnormalities were trisomies (42%) and monosomies (28%). FISH results demonstrated more chromosomal losses than gains. Screening of BUB1B in our two patients failed to identify any mutation. A review of the 21/35 patients screened for BUB1B demonstrated three clinical pictures. Patients with monoallelic BUB1B mutations were severely affected with Dandy‐Walker complex (7/8), cataracts (6/6), and Wilms' tumor (7/8); premature chromatid separation (PCS) was observed in 8/8 propositi and 7/7 carrier parents. Patients without BUB1B mutations were mildly affected with no evidence of cancer, Dandy‐Walker malformation or cataract, and rarely (1/7) showed PCS. Finally, patients with biallelic BUB1B mutations showed a moderate phenotype. The distinct MVA clinical groups delineated here point to involvement of at least another mitotic spindle checkpoint gene in addition to the BUB1B gene. © 2008 Wiley‐Liss, Inc.
Novel thermally and mechanically stable hydrogel for enzyme immobilization of penicillin G acylase via covalent technique
Authors: Elnashar Magdy M. M. , Yassin Mohamed A. , Kahil Tarek 
Published: June 2008

Abstractκ‐Carrageenan hydrogel crosslinked with protonated polyethyleneimine (PEI+) and glutaraldehyde (GA) was prepared and evaluated as a novel biocatalytic support for covalent immobilization of penicillin G acylase (PGA). The method of modification of the carrageenan biopolymer is clearly illustrated using a schematic diagram and was verified by FTIR, elemental analysis, DSC, and INSTRON using the compression mode. Results showed that the gels' mechanical strength was greatly enhanced from 3.9 kg/cm2 to 16.8 kg/cm2 with an outstanding improvement in the gels thermal stability. It was proven that, the control gels were completely dissolved at 35°C, whereas the modified gels remained intact at 90°C. The DSC thermogram revealed a shift in the endothermic band of water from 62 to 93°C showing more gel‐crosslinking. FTIR revealed the presence of the new functionality, aldehydic carbonyl group, at 1710 cm−1 for covalent PGA immobilization. PGA was successfully immobilized as a model industrial enzyme retaining 71% of its activity. The enzyme loading increased from 2.2 U/g (control gel) to 10 U/g using the covalent technique. The operational stability showed no loss of activity after 20 cycles. The present support could be a good candidate for the immobilization of industrial enzymes rich in amino groups, especially the thermophilic ones. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation of modified polystyrene with maleic anhydride in the presence of different solvents
Authors: Sayed Wafaa M. 
Published: June 2008

AbstractPolystyrenes (PS's) with different molecular weights were chemically modified with maleic anhydride (MA) with of benzoyl peroxide as an initiator or with a cationic catalyst such as FeCl3 in chloroform. The effect of the solvents (i.e.; chloroform, benzene, toluene, xylene, and tetrahydrofuran), PS and MA concentration, molecular weight of PS, and type of catalyst used in the chemical modification was studied. The rate of the reaction was different with different solvents because of chain transfer to the solvent. The IR spectra of the modified polystyrene (MPS) existing at the end of the chemical modification were taken to show the presence of a carboxyl group fixed to the aromatic ring of PS. The kinetics of the reaction of MPS with MA were also studied. MPS samples containing COCHCH COOH fragments inside chains were crosslinked, as proven by differential thermal analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Use of methacrylic acid grafted poly(ethylene terephthalate) fibers for the removal of basic dyes from aqueous solutions
Authors: Arslan Metin , Yiğitoğlu Mustafa 
Published: June 2008

AbstractA reactive fibrous adsorbent was prepared through the grafting of a methacrylic acid monomer onto poly(ethylene terephthalate) fibers for the removal of basic dyes such as methylene blue and basic red 9 from aqueous solutions through a batch adsorption method. Effects of various parameters such as the grafting yield, pH, treatment time, initial dye concentration, and adsorption temperature on the amount of dye adsorbed onto reactive fibers were investigated. The adsorption amounts of basic dyes increased with increases in the grafting yield, pH, treatment time, initial dye concentration, and adsorption temperature. The rates of adsorption conformed to pseudo‐second‐order kinetics with a good correlation. The equilibrium data for methylene blue and basic red 9 adsorption fit the Langmuir equation, with maximum adsorption capacities of 200 and 250 mg/g, respectively. The adsorption rates of two basic dyes were much higher on the grafted poly(ethylene terephthalate) fiber than on the ungrafted poly(ethylene terephthalate) fiber. Within 45 min, about 99% of the cationic dyes was removed from the solutions (400 mg/L) by methacrylic acid‐graft‐poly (ethylene terephthalate) fibers. The highest desorption amounts for methylene blue and basic red 9 were 62 and 84%, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Formation of new thermosets by the reaction of cyanates with thiophenols
Authors: Bauer Monika , Bauer Jörg 
Published: June 2008

AbstractSulfur‐containing aromatic thermosets, mainly consisting of aryloxy‐ and arylthio‐substituted 1,3,5‐triazines, have been prepared through the reaction of difunctional cyanates with mono‐ and difunctional aromatic thiols. A straightforward three‐step reaction scheme is proposed and verified by the identification of key substances: (1) the addition of thiol and cyanate groups, (2) the stepwise addition of (thio)imino carbonic esters with one another, and (3) the ring closure of chain‐extended (thio)imino carbonic esters to form 1,3,5‐triazines. Reactions of types 2 and 3 are associated with an abstraction of phenol or thiophenol, which can enter into reaction 1 again. Characterization of the curing behavior of dicyanate of bisphenol A with thiophenol as well as dimercaptodiphenyl sulfide by differential scanning calorimetry shows that the reaction rates are significantly enhanced by the admixture of thiols to the cyanate. Dynamic mechanical analysis of resulting thermosets showed that large amounts of comonomers can be incorporated into the network resulting in a decrease of glass temperature but increase of fracture toughness. Finally, the fully cured thermosets resulting from the reaction of dicyanate of bisphenol A with different admixtures of dimercaptodiphenyl sulfide were characterized by cone calorimetry to get information about flame retardancy. The flame retardancy is influenced by incorporation of dimercaptodiphenyl sulfide into the triazine network only slightly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and properties of aliphatic polycarbonates derived from carbon dioxide, propylene oxide and maleic anhydride
Authors: Song P. F. , Xiao M. , Du F. G. , Wang S. J. , Gan L. Q. , Liu G. Q. , Meng Y. Z. 
Published: June 2008

AbstractTerpolymerization of carbon dioxide (CO2) with propylene oxide (PO) and maleic anhydride (MA) was successfully carried out using supported zinc glutarate catalyst. Consequently giving high molecular weight poly(propylene carbonate maleate) (PPCMA) in a very high yield (72.5 g polymer/g catalyst). The resulting terpolymers were fully characterized by FTIR, 1H NMR, 13C NMR, and wide‐angle X‐ray diffraction (WAXD) techniques. NMR measurements showed that PPCMA had an almost alternating structure for the components of carbon dioxide and PO. The influence of molecular weight and MA content on the properties of PPCMA was also investigated. Differential scanning calorimetry (DSC) measurements revealed that the glass transition temperature (Tg) of PPCMA increased with increasing molecular weight. Thermogravimetric analysis (TGA) indicated that PPCMA51 exhibited a very high decomposition temperature (263°C) due to the introduction of the double bond of MA into the backbone of terpolymer. The terpolymers with double bonds can be readily subjected to crosslinking reaction in high temperature to give a slightly crosslinked PPCMA, which exhibit superior thermal stability. Tensile tests also showed that the mechanical properties of PPCMA increased with increasing molecular weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of the functionality of polyol in rigid polyurethane foams
Authors: Lim Ho , Kim Sung Hee , Kim Byung Kyu 
Published: June 2008

AbstractRigid polyurethane foams (RPUFs) have been fabricated from crude MDI (CMDI) and polypropylene glycols (PPGs) of various functionalities (f) with HFC 365mfc as a blowing agent. Foam density increased, cell size and density distribution decreased with increasing f while the closed cell content was kept constant over 92%. The gel time, tack‐free time, volume change, and the thermal conductivity of the foam showed a minimum with f = 5, and the existence of minimum has been explained in terms of a large mixture viscosity and cell wall resistance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Back‐calculation of the die swell phenomenon of rubber compounds by means of torsional rheometry
Authors: Müllner Herbert W. , Ernst Gerald , Eberhardsteiner Josef 
Published: June 2008

AbstractThe die swell phenomenon of capillary experiments with various ratios of length to diameter of capillary dies is investigated. This knowledge is important for the design of injection heads for the extrusion of rubber profiles. To predict the die swell of capillary experiments, additional tests with a torsional rheometer has been performed. For polymers, the combination of such rheological data is possible under usage of the empirical relationship by Cox and Merz. With the introduction of a scaling factor this rule is also applicable for rubber compounds. With the relationship of Laun and the new scaling factor a back‐calculation of the first normal stress difference is done. Finally, the die swell of arbitrary capillary experiments for industry‐used rubber compounds can be computed without introduction of new material parameters. For this task a relationship of Tanner is used, which connects the die swell and the first normal stress difference. An adaptation of the capillary viscometer allows the experimental investigation of the die swell and, thus, a validation of the presented approach. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Morphological aspects of rubber fracture and wear
Authors: Bieliński D. M. , Dobrowolski O. , Przybytniak G. 
Published: June 2008

AbstractMorphology of carbon black (CB)‐filled rubber was studied with AFM and SEM and the classification of filler agglomerates, based on their internal structure and filler–matrix interactions, has been proposed. It varies according to the activity of CB and the kind of rubber. It has been shown that fracture of rubber starts either inside filler agglomerates (de‐cohesion) or in a filler–matrix interphase (de‐adhesion) initiating wear of the material. Microscopic observations correlate well with TGA and EPR data of wear debris collected during friction of rubber. The increase of thermal stability of CB and the appearance of additional spin signals, respectively, for elongated samples or debris, are proposed to be associated with de‐cohesion or de‐adhesion of the agglomerates. New approach to the fracture of rubber called “fatal agglomerate concept” is presented. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Nonclinical pharmacokinetics of BMS‐292655, a water‐soluble prodrug of the antifungal ravuconazole
Authors: Knipe Jay O. , Mosure Kathleen W. 
Published: June 2008

AbstractThe phosphate ester, BMS‐292655, was developed as a water‐soluble prodrug of the antifungal agent, ravuconazole (BMS‐207147). BMS‐292655 was comparatively stable in rat, beagle dog, cynomolgus monkey and human plasma, but was hydrolysed upon incubation with liver S9 preparations from all species. The major product in rat, monkey and human S9 was BMS‐207147, while in dog S9, the intermediate ester, BMS‐300043, predominated. BMS‐300043 itself was more stable in dog S9 than in S9 preparations from the other species. Intravenous administration of BMS‐292655 to rats, beagle dogs and cynomolgus monkeys indicated species differences in the extent of formation of BMS‐207147 (monkeys>rats>dogs). The lower overall generation of BMS‐207147 in dogs was consistent with the presence of circulating plasma levels of BMS‐300043. BMS‐300043 was present in monkey plasma but not detectable in rat plasma. The conversion of BMS‐292655 to BMS‐207147 in the presence of human S9 indicated the potential for BMS‐292655 to function as a BMS‐207147 prodrug in humans. The similarity in the hydrolysis of BMS‐292655 when incubated with human and monkey S9 in vitro, coupled with the effective release of BMS‐207147 from BMS‐292655 upon i.v. administration to monkeys, is consistent with this conclusion. Copyright © 2008 John Wiley & Sons, Ltd.