bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origins and processing of organic matter in the Amazon River as indicated by carbohydrates and amino acids
Authors: Hedges John I. , Cowie Gregory L. , Richey Jeffrey E. , Quay Paul D. , Benner Ronald , Strom Mike , Forsberg Bruce R. 
Published: May 2010

Aldose, amino acid, and elemental compositions were determined for flux‐weighted samples of coarse (>63 µm) and fine (<63 µm) particulate organic material and ultrafiltered (>1,000 Daltons) dissolved organic matter collected at three sites along the Brazilian Amazon River and six of its major tributaries. Concentrations of total organic C (TOC) were relatively uniform (550±100 µM) at all sites, with DOC comprising the major (50–100%) component. An average of 77% of the total DOC was isolated by ultrafiltration.The greatest compositional differences observed in the Amazon River system were among the coarse, fine, and dissolved organic fractions. All coarse particulate fractions were nitrogen‐poor (atomic C : N = 21) and exhibited stable carbon isotope, aldose, and amino acid compositions similar to those of angiosperm tree leaves. Coarse particulate organic materials, although the least degraded of the three fractions, had lost appreciable carbohydrate and had immobilized excess nitrogen of apparent bacterial origin. Fine particulate materials were more nitrogen‐rich (C : N = 9) than coarse counterparts and had lower total aldose yields and glucose percentages. Fine particles gave greater total yields of amino acids, characterized by high ratios of basic vs. acidic components. Coexisting dissolved organic materials recovered by ultrafiltration were nitrogen‐poor (C : N = 27–52) and yielded the lowest amounts of aldoses, among which deoxy sugars were concentrated. Dissolved fractions gave extremely low yields of amino acids in mixtures that were enriched in nonprotein components and in acidic vs. basic molecules. These yield and composition patterns are consistent with a “regional chromatography” model in which highly degraded leaf material is solubilized and then partitioned between soil minerals and water during transport to the river, resulting in suspended fine particulate organic materials of soil origin that are nitrogen‐rich and coexisting dissolved organic substances that are nitrogen‐poor.
Development of a new method for direct measurement of pCO2 in natural waters
Authors: Che Guangwei , Ilmberger Johann 
Published: May 2010

A new direct measurement method for pCO2 in water samples is presented. The technique is based on the fact that the dissolved CO2 in a water sample is able to diffuse through the wall of a thin silicon rubber tubing, whereas the dissolved ions remain. The CO2 passing through the wall is equilibrated with the deionized water flowing inside the tubing, and its electric conductivity is measured by a conductivity flow cell afterward.Laboratory experiments on 255 CO2 standard samples with pCO2 varying from 300 to 30,000 ppmv show a mean CO2 exchange ratio R across the silicon rubber membrane of 0.95, with SD = ±0.04. For pCO2 in the 40–300 ppmv range (40 CO2‐standard samples), a mean exchange ratio R = 0.93±0.09 has been determined. The detection limit of this method is 0.6 µM (∼18 ppmv at 25°C).
Determination of phytoplankton crops by top‐down and bottom‐up mechanisms in a group of English lakes, the West Midland meres
Authors: Moss Brian , McGowan Suzanne , Carvalho Laurence 
Published: May 2010

Twenty‐four lake basins formed in glacial drift ranged in maximum depth from 1.5 to 31 m and were characterized by generally low inorganic N concentrations and very high total P concentrations. The high P values were in some cases related to farm effluent pollution but in many others, despite annual mean values up to 1.46 mg liter−1, appear natural and due to the local mineralogy.For the entire group, there were no significant relationships between mean growth season chlorophyll a concentration and any measured chemical, morphometric, or zooplankton variable. When the group was divided on the basis of maximum depth and presence or absence of thermal stratification in summer into a shallow group (<3 m) and a deep group (>3 m), strong inverse correlation was obtained between chlorophyll a and cladoceran abundance in the shallow group and strong direct correlation with inorganic N in the deep group. Grazer control in the shallow group is probably linked with the dominance of submerged macrophytes and the refuges they provide for grazers. Some of the controversy presently surrounding the relative importance of top‐down vs. bottom‐up control of phytoplankton populations may thus be removed if consideration is given to the morphometry of the lakes.
A model of growth and development in copepods
Authors: van den Bosch Frank , Gabriel Wilfried 
Published: May 2010

We present a model for the growth and development of copepods based on the simple assumption that a constant fraction of assimilated carbon is invested in the formation of a new carapace. The individual molts into the next stage when the weight of the accumulated carapace building bricks is a fixed fraction of the body mass at the beginning of the stage. This simple stage‐transition coordinating system is built into an individual growth model.The model predicts decreasing stage duration and increasing body weight with increasing food concentrations. These trends closely agree with published data. Anisochronality, as found in many copepod species, agrees with model predictions. Acartia species usually show isochronal development. The model predicts isochronal development for one particular value of a parameter of the feeding process. Literature data show that this parameter value is realistic for Acartia spp. “Equiproportionality” is predicted by the model. The model thus shows close agreement with observed growth and development patterns.
Retention of elements absorbed by juvenile fish (Menidia menidia, Menidia beryllina) from zooplankton prey
Authors: Reinfelder John R. , Fisher Nicholas S. 
Published: May 2010

Radiolabeled copepods (Acartia spp.) were fed to juvenile silversides (Menidia menidia and Menidia beryllina) to study clement absorption in the fish. Copepods were reared from nauplii in the presence of different radiotracers (14C,109Cd, 57Co, 32P,35S,75Se, or 65Zn) and were analyzed for relative concentrations of these elements in their tissue fractions. Copepod exoskeletons contained nearly all of the trace metals (>97%), 60% of the Se, and less than half of the C, P, and S accumulated by the copepods. Within the nonexoskeleton tissues of the copepods, nonpolar (CHCl3 extractable) material contained 34 and 24% of the total C and P, but only 8 and 2% of the total S and SeAbsorption efficiencies of trace metals in juvenile silversides (2.7% for Cd, 2.1% for Co, 6.2% for Zn) were an order of magnitude lower than those for nonmetals (29% for Se, 50% for S and C, 60% for P). The absorption efficiencies in the juvenile silversides of all seven elements studied were directly related to the percent of each element in the nonexoskeleton fraction of the copepod prey, indicating that the fish absorbed the soft tissues of the copepods and egested the chitinous exoskeleton and its associated elements.
Freshwater flow into a coastal embayment: Groundwater and surface water inputs
Authors: Millham Newton P. , Howes Brian L. 
Published: May 2010

Freshwater discharge to a shallow coastal embayment was measured with two upland hydrologic and three embayment physical methods for 2 yr. Parallel measurements from the five methods ranged from 3,900 (±630) to 9,400 (±3,400) m3 d−1, and four of the methods showed close agreement and averaged 4,800 (± 670) m3 d−1. The most precise estimate of discharge was from a chloride balance, while the best understanding of the rate and pattern of groundwater flow was from a Darcian streamtube approach.Groundwater dominated the freshwater budget, accounting for >95% of the total annual input, and was partitioned almost equally between direct seepage to embayment waters and seepage to a stream with final discharge via surface flow. Freshwater inputs decreased rapidly toward the mouth of the estuary and >80% entered into the upper half. The lack of fixed watershed boundaries resulted in large errors in both the location and area of the topographically defined watershed when compared to a watershed defined by water‐table mapping. Seasonal variations were found in both the boundaries of the watershed (8%) and in groundwater discharge (6‐fold) in response to changing water‐table gradients due to recharge. Hydrologic alterations of the upland through the import of water and the increased recharge from impermeable surfaces led to an apparent increase in the total freshwater discharge to the embayment of nearly 50% over “natural” levels.
Investigating household food interpurchase behavior through market segmentation
Authors: Dong Diansheng , Kaiser Harry M. 
Published: May 2010

AbstractIn this study, a market segmentation approach is developed and applied to analyze U.S. households' cheese purchases. The segmentation is based on household interpurchase time, or the hazard rate of purchases. In this study, four segments have been discovered in the U.S. market for household cheese purchases. Two of the segments jointly represent about 40% of all cheese‐purchasing households and are characterized as frequent buyers with an average interpurchase time of 2 weeks. These frequent‐purchase households are larger in size, have greater incomes, have a smaller proportion of African Americans, and are insensitive to coupons. They are often described in the marketing literature as loyal customers. In contrast, the other two segments, which jointly represent about 60% of the households, are characterized by infrequent buyers with an average interpurchase time of 6 weeks. These infrequent‐purchase households are smaller in size, have less income, have a higher proportion of African Americans, and are sensitive to coupons. Marketing promotions typically target the infrequent‐purchase households. [EconLit citations: D12, C51, C41]. © 2010 Wiley Periodicals, Inc.
Failure to confirm genetic association of the FXYD6 gene with schizophrenia: The Japanese population and meta‐analysis
Authors: Iwata Yasuhide , Yamada Kazuo , Iwayama Yoshimi , Anitha Ayyappan , Thanseem Ismail , Toyota Tomoko , Hattori Eiji , Ohnishi Tetsuo , Maekawa Motoko , Nakamura Kazuhiko , Suzuki Katsuaki , Matsuzaki Hideo , Tsuchiya Kenji J. , Suda Shiro , Sugihara Genichi , Takebayashi Kiyokazu , Yamamoto Shigeyuki , Iwata Keiko , Mori Norio , Yoshikawa Takeo 
Published: May 2010

AbstractThe FXYD domain‐containing ion transport regulator 6 (FXYD6) gene encodes phosphohippolin that regulates cellular ion transport by altering the kinetic properties of Na,K‐ATPase. Phosphohippolin is highly expressed in brain regions that are relevant to schizophrenia. The FXYD6 gene is located at chromosome 11q22–24, one of the most established linkage regions for schizophrenia. Therefore, it may be possible that genetic variants in FXYD6, including the regulatory genomic elements could cause abnormal function or expression of phosphohippolin and increase the genetic risk for schizophrenia. A previous study suggested that polymorphisms in FXYD6 are associated with schizophrenia in UK samples. However, conflicting results have been reported in the Japanese population. In this study, we aimed to test the prior genetic association findings using different samples from the ethnically homogeneous Japanese population (1,060 schizophrenic patients and 1,060 age‐ and sex‐matched controls). From the FXYD6 gene, we examined six single nucleotide polymorphisms (rs11216573, rs555577, rs1815774, rs4938445, rs4938446, and rs497768), all of which were previously analyzed for association. We did not detect any significant allelic, genotypic or haplotypic association in our Japanese samples. Meta‐analysis incorporating previous and the present studies also showed that the FXYD6 gene is not associated with schizophrenia. We conclude that the FXYD6 gene does not have a major influence on susceptibility to schizophrenia across populations. © 2010 Wiley‐Liss, Inc.
Flame retardance and mechanical properties of a polyamide 6/polyethylene/surface‐modified metal hydroxide ternary composite via a master‐batch method
Authors: Liu Shu‐Mei , Huang Jun‐Yi , Jiang Zhi‐Jie , Zhang Chen , Zhao Jian‐Qing , Chen Jun 
Published: May 2010

AbstractSurface‐modified aluminum hydroxide and magnesium hydroxide mixtures (SAMHs) were filled with linear low‐density polyethylene (LLDPE) with a maleic anhydride grafted polyethylene (PE) compatibilizer to produce a SAMH master batch, which was then dispersed in polyamide 6 (PA6) to yield a PA6/PE/SAMH (50/20/30 by weight ratio) ternary composite. Through such a master‐batch method, an effective flame retardance UL94 V‐0 rating at a 3.2 mm thickness with a 33% limiting oxygen index was achieved. The flame‐retardance mechanism of the ternary composite was investigated by thermogravimetric analysis and scanning electron microscopy/energy dispersive X‐ray spectroscopy analysis. A cocontinuous PA6/PE polymer host and a preferential dispersion of SAMH particles in the matrix induced the formation of a compact flame‐resistant char layer and a high residue rate during burning; this resulted in the desired flame retardance of the ternary composite. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Systematic study of interfacial interactions between clays and an ionomer
Authors: Gao Yan , Choudhury Namita Roy , Dutta Naba K. 
Published: May 2010

AbstractTo study the interfacial interactions between an ionomer [poly(ethylene‐co‐acrylic acid) neutralized by zinc salts (PI)] and clays, PI–clay nanocomposites were prepared using a solution method. Two types of commercially available montmorillonite clays respectively K10 and KSF were used, and were modified with organic modifiers with chain lengths of 12–18 carbons. The interactions between the PI, clays, and modifiers were evaluated through study of the structure, morphology, and properties of the PI–clay nanocomposites. We found that the modifiers were successfully intercalated into the clay layers (Fourier transform infrared spectroscopy). The clay modified with a long‐chain agent showed an exfoliated nature in the nanocomposite. The thermal stability and storage modulus of PI were improved greatly by the addition of the clays, especially when the long‐chain modifier was used (thermogravimetric analysis and dynamic mechanical analysis). The differential scanning calorimetry results show that clay layers are inserted into the clusters because of solvent‐directed morphological evolution, so the transition of the ionic domains and the crystallinity of PI are changed. The interaction between PI, the modifier, and the silicate layer played an important role in the determination of the properties of the nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Evolutionary computing approach for evaluating flory distribution curves in gel permeation chromatography: Study of the poly(1‐octene) system
Authors: Singh Gurmeet , Kaur Sukhdeep , Naik Dhananjay G. , Gupta Virendra K. 
Published: May 2010

AbstractWe carried out deconvolution of the molecular weight distribution curves from gel permeation chromatography for polyolefins into individual active sites considering Flory distribution by an evolutionary‐computing‐based real‐coded genetic algorithm, a nonlinear multivariate optimization algorithm. We applied the deconvolution to homopolymers of 1‐octene synthesized using heterogeneous Ziegler–Natta catalysts with different amounts of hydrogen. The molecular weight distribution was deconvoluted in to five Flory distributions, which showed a sensitivity to hydrogen amounts. With no hydrogen presence, the peaks corresponding to high‐molecular‐weight fractions were intense. As the amount of hydrogen was increased, not only did the intensities of the high‐molecular‐weight peaks decrease, but also peaks corresponding to low‐molecular‐weight fractions were observed. The method allowed us to determine the active site distribution of the polymer molecular weight distribution obtained from gel permeation chromatography. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Relationship between the material properties and fatigue crack‐growth characteristics of natural rubber filled with different carbon blacks
Authors: Nie Yijing , Wang Bingyin , Huang Guangsu , Qu Liangliang , Zhang Peng , Weng Gengsheng , Wu Jinrong 
Published: May 2010

AbstractAn investigation of the influence of different types of carbon black on fatigue crack‐growth behavior was undertaken. Fatigue tests were carried out on edge‐notched specimens under cyclic tension loading. A power‐law dependency between the crack‐growth rate and tearing energy was obtained. Natural rubber (NR) filled with N330 (the mean diameter is 30 nm) carbon black possessed the lowest values of exponent b and constant B (the two crack growth parameters determined from cyclic crack growth testing), which denoted the strongest resistance to crack growth at a given tearing energy. Strain‐induced crystallization was investigated by the modified Mooney–Rivlin equation and showed the earliest appearance and strongest ability of the crystallization of the NR/N330 composite at the largest amount of bound rubber. The study on the viscoelastic properties by dynamic mechanical analysis confirmed that the NR/N330 composite had the largest viscoelastic contribution, which was attributed to the viscoelastic dissipation in the viscoelastic region in front of the crack tip. All of these results confirm the best crack‐propagation resistance of NR filled with N330. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Characterization of acrylic acid grafted poly(ethylene terephthalate) fabric
Authors: Grover Navdeep , Singh Harpal , Gupta Bhuvanesh 
Published: May 2010

AbstractThe preirradiation grafting of acrylic acid (AA) onto poly(ethylene terephthalate) (PET) had been found to affect the thermal and physical characteristics of fabric. The grafted fabrics with various graft levels were characterized by thermal gravimetric analysis (TGA), ATR‐FTIR spectroscopy, contact angle, differential scanning calorimetry (DSC), X‐ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The initial decomposition temperature and T50 were increased with the increase in degree of grafting. The percentage crystallinity was decreased as the degree of grafting increases. The detailed elemental analysis was done by X‐ray photoelectron spectroscopy (XPS). The atomic ratio (O1s/C1s) was found to increase significantly with increasing the degree of grafting and reached 0.64 at 14.5% grafting from 0.38 for virgin PET. The surface topography and morphology was strongly influenced as the degree of grafting was increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Ionic conductivity of solid polymer electrolytes for dye‐sensitized solar cells
Authors: Kim Joo Wan , Bae Young Chan 
Published: May 2010

AbstractWe developed an ionic conductivity model of solid polymer electrolytes for dye‐sensitized solar cells (DSSCs) based on the Nernst–Einstein equation in which the diffusion coefficient is derived from the molecular thermodynamic model. We introduced concentration‐dependence of the diffusion coefficient into the model, and the diffusion coefficient was expressed by differentiating the chemical potential by concentration. The ionic conductivities of polymer electrolytes (PEO/LiI/I2 system) were investigated at various temperatures and compositions. We prepared a set of PEO in which an EO : LiI mole ratio of 10 : 1 was kept constant for PEO·LiI·(I2)n compositions with n = 0.02, 0.05, 0.1, 0.15, 0.2, and 0.3 (mole ratio of LiI : I2). The ionic conductivities of the electrolytes were measured using a stainless steel/polymer‐electrolyte/stainless steel sandwich‐type electrode structure using alternating current impedance analysis. The values calculated using the proposed model agree well with experimental data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of sodium hexametaphosphate concentration on the swelling and controlled drug release properties of chitosan hydrogels
Authors: Sánchez‐Díaz Juan C. , Becerra‐Bracamontes Fausto , González‐Álvarez Alejandro , Cruz‐Barba L. Emilio , Martínez‐Ruvalcaba Agustín 
Published: May 2010

AbstractAn ionically crosslinked polymer network composed of chitosan and sodium hexametaphosphate (SHMP) was synthesized to determine their swelling and ascorbic acid release kinetics at various SHMP concentrations. The chitosan/SHMP hydrogels were synthesized using an acetic acid aqueous solution (1% v/v). Ionization constants (pKb) of the SHMP were obtained by potentiometric titration. The results show that the SHMP was hydrolyzed in acidic medium forming orthophosphate and trimetaphosphate. The swelling percentages were measured at different swelling media pH's; the higher swelling capacities were for the systems that were swollen in neutral solution. Also, it was studied the ionic crosslinking degree by turbidimetric titration, comparing the electrostatic interactions between the chitosan and the SHMP; the results shows that electrostatic interactions between the amine groups of the chitosan and the anionic groups of the SHMP are dependent of the swelling medium pH. The ascorbic acid diffusion inside the hydrogel follows the second law of Fick, and the diffusion coefficients were obtained for different SHMP concentrations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effect of ligand molecular weight on copper salt catalyzed oxidative coupling polymerization of 2,6‐dimethylphenol
Authors: Zhao Ying , Wu Linbo , Li Bo‐Geng , Zhu Shiping 
Published: May 2010

AbstractPolyphenylene oxide (PPO) was prepared via oxidative coupling polymerization of 2,6‐dimethylphenol (DMP) catalyzed by copper salt. The ligand was a novel series of random copolymers (PSVP) of styrene and 4‐vinylpyridine prepared by reversible addition‐fragmentation chain transfer (RAFT) copolymerization. The copolymers with well‐controlled molecular weight (MW) were used to study the effects of ligand molecular weight on the catalytic activity and selectivity. It was found that the catalytic activity increased with the molecular weight but there existed an upper MW limit above which no further increase in activity could be achieved. With PSVP of FvPy = 0.39, the critical MW was about 5000 g/mol. The mechanism involved in the successive complexation of copper ions and PSVP was elucidated and the equilibrium constants were estimated by pH titration. It was found that the macromolecular ligand was in favor of bridging CuII ions that formed catalytically active dinuclear copper‐amine complexes. However, the catalytic selectivity was almost independent of the ligand MW. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Adsorption of diclofenac sodium from aqueous solution using polyaniline as a potential sorbent. I. Kinetic studies
Authors: Bajpai S. K. , Bhowmik Mousumi 
Published: May 2010

AbstractThis study describes dynamic uptake of antibiotic drug diclofenac sodium from aqueous solution using polyaniline as sorbent. The sorbent polyaniline was prepared by oxidative polymerization of aniline and characterized by FTIR spectrum analysis and TGA. The optimum sorbent/sorbate mg/mL ratio and pH range for maximum drug uptake have been found to be 2.0 and 5.5 to 10.5, respectively. Out of various kinetic models applied, the pseudo second‐order kinetic equation has been found to fit well on the kinetic uptake data. The pseudo second‐order rate constants for adsorption have been found to be 0.982 × 10−2, 7.24 × 10−2, and 18.09 × 10−2min−1mg−1g for drug solutions with initial concentrations of 10, 20, and 30 mg L−1, respectively. The overall sorption process has been found to be governed by intraparticle diffusion.The sorptive removal of drug from aqueous solution has also resulted in enhancement in bacterial growth ofEscherichia coli.© 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010