bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elimination of Zinc from Roof Runoff through Geotextile and Clinoptilolite Filters
Authors: Athanasiadis Konstantinos , Helmreich Brigitte , Wilderer Peter A. 
Published: February 2005

AbstractDirect infiltration of roof runoff into the ground may pose a potential risk of soil and groundwater contamination. The performance of two different barrier materials for the retention of zinc from roof runoff of an eleven year old zinc roof was examined in a field study. As barrier materials geotextile and clinoptilolite were applied. Automatic samplers were used to take samples both at the inlet and at the outlet of the retention facility. Samples of twenty rain events were examined. Zinc was detected in the roof runoff in concentrations of up to 25 mg/L, and lead which originates from the tin‐solder was present in concentrations of up to 84 μg/L. Under most circumstances, a first flush could be observed for the analysed substances. No retention of heavy metals was observed, where only geotextile was used as a barrier material. The clinoptilolite filter was able to adsorb up to 97 % of zinc from the roof runoff.
The Determination of Relationship between Zooplankton and Abiotic Factors Using Canonical Correspondence Analysis (CCA) in the Ova Stream (Ankara/Turkey)
Authors: Akbulut Nuray (Emir) 
Published: February 2005

AbstractIn this study totally 25 rotifer species, 3 cladocerus species, and 2 copepoda species were identified in Ova Stream. Among zooplankton rotifer species were dominant. Population densities of planktonic organisms were calculated as individual per cubic meter and the relationship of the planktonic organisms with physicochemical parameters was determined applying canonical correspondence analysis (CCA). Also diversity index has been calculated according to the sampling stations. According to the results, the diversity index changes between stations and sampling time. The CCA results show that the rotifer species Keratella, Notholca showed negative correlation with the increasing chemical parameters and temperature but Brachionus, Mytilina, Colurella, and Testudinella have positive correlation with increasing temperature.
Optimisation of the Operation of an Electrochemical Process To Treat TBT‐contaminated Sediments on a Pilot Scale
Authors: Arevalo Eduardo , Keller Arne , Stichnothe Heinz , Calmano Wolfgang 
Published: February 2005

AbstractSince at least three decades tributyltin had been commonly used in paint formulations to protect ship hulls and submersed surfaces from fouling. This has resulted in negative and Technology, effects to the marine environment due to its high toxicity towards non‐target organisms and to its accumulation in sediments, especially near point sources of pollution. Even if a ban of TBT for its application in anti‐fouling paints is enforced the problem of TBT‐contaminated sediments will remain for the coming years due to the low degradation rates of organotin in sediments. In this work an electrochemical process at a pilot scale to destroy TBT in sediments was investigated. Previous experiences at a laboratory and technical scale have demonstrated the potential of this process to electrolytically degrade organotin species in sediments.This article deals with the optimisation of the pilot plant performance in terms of organotin degradation and operation costs monitoring additionally the effect of the electrochemical treatment on other pollutants such as heavy metals, PCBs, and PAHs.The aim was to investigate by means of a parametric study the range of operating conditions required to destroy TBT down to concentrations lower than 100 μg/kg; to determine the influence of those parameters on the performance of the process; and to evaluate the operation costs associated to the process. It was determined that it was possible to destroy TBT down to 100 μg/kg at current densities in the range of 4.4 to 6.6 mA/cm2 and chloride concentrations of least of 0.2 mol/L with operation costs of 13 to 18 EUR/m3.
Retardation of Fin Regeneration in Freshwater Fish Oreochromis mossambicusby Zinc
Authors: Verma Yogendra 
Published: February 2005

AbstractRegeneration of partially amputated caudal fin was studied in freshwater fish Oreochromis mossambicus exposed to sublethal concentrations of zinc (5.0 mg L—1 and 10.0 mg L—1) under ambient laboratory conditions over a period of 20 days. Caudal fin regeneration was measured on 5th, 10th, 15th and 20th day of exposure and after amputation. Significant ( p < 0.05) retardation in fin regeneration was observed on day 5th and 10th in fish exposed to the nominal concentration of 5.0 mg L—1 Zn, while retardation was found highly significant ( p < 0.01) at all the observations in 10.0 mg L—1. The maximum inhibition in caudal fin regeneration (20.8 % and 24.3 %) was found during the initial observation at both of the concentrations (5.0 mg L—1 and 10.0 mg L—1) of zinc exposure. Later on the regeneration rate was almost as good as in the control group. Thus in this study fin regeneration was significantly inhibited at all time points following Zn exposure as a detrimental effect of Zn to fish. This study demonstrates that fish caudal fin regeneration is a simple assay, sensitive and easy to perform, and can serve as a model to determine the toxicity of pollutants in aquatic environment.
Optimal feeding for tower‐type reactors
Authors: Fu Chun‐Chong , Lu Shih‐Yuan , Wu Wen‐Teng 
Published: February 2005

AbstractIn tower‐type reactors, poor mixing is a major concern in fermentation processes. As an attempt to improve the mixing efficiency, an algorithm based on the analytic solution of the modified network‐of‐zones model and application of the singular value decomposition technique is proposed to determine the optimal feeding locations and corresponding amounts of feed in airlift reactors, bubble column reactors, and airlift reactors with wire‐mesh draft tube. The optimal feeding locations and corresponding amounts of feed predicted by the algorithm are in good agreement with the experimental results. The proposed algorithm is proved to be an effective method for optimizing the feeding operation to improve the mixing efficiency for the three tower‐type reactors. © 2005 American Institute of Chemical Engineers AIChE J, 51: 713–724, 2005
Three‐dimensional simulation of bubble column flows with bubble coalescence and breakup
Authors: Chen P. , Duduković M. P. , Sanyal J. 
Published: February 2005

AbstractThree‐dimensional (3‐D) Euler/Euler simulations of two‐phase (gas/liquid) transient flow were performed using a multiphase flow algorithm based on the finite‐volume method. These numerical simulations cover laboratory‐scale bubble columns of different diameters, operated over a range of superficial gas velocities in the churn‐turbulent regime (8 to 30 cm/s) and at different operating pressures (up to 1 MPa). The bubble population balance equation (BPBE) is implemented in the two‐fluid model (TFM) and algebraic slip mixture model (ASMM). Simulated time‐averaged axial liquid velocity, turbulence stress, and gas holdup are compared with experimental data of Chen et al., Ong, and Shaikh et al. Moreover, to ensure the experimentally observed lack of dependency of holdup radial profiles on column height in the fully developed region, coalescence rates in the computations had to be enhanced consistently compared to model‐predicted values. Quantitative agreement is then obtained between the experimental data and simulations for the time‐averaged gas holdup and axial liquid velocity profiles. However, the simulations significantly underestimate the turbulent stress because the velocity field cannot be fully resolved. Simulated bubble size distributions indicate that the volume fraction of small bubbles is uniform in a cross section, whereas that of the large bubbles peaks in the center of the column. The simulation correctly captures the high‐pressure effect, which at fixed gas superficial velocity pushes the bubble column flow toward bubbly flow. The simulation also predicts that, although the small bubble volume fraction may not change with superficial gas velocity in the churn‐turbulent flow regime, the bubble size distribution still remains single modal but is wider and contains larger bubble sizes when superficial gas velocity is increased. © 2005 American Institute of Chemical Engineers AIChE J, 51: 696–712, 2005
Kinetics and mechanism of the K2CrO4NaAsO2 redox‐initiated aqueous polymerization of acrylonitrile
Authors: Maity Arjun , Biswas Mukul 
Published: February 2005

AbstractThe kinetics and mechanism of acrylonitrile polymerization initiated by a redox pair [potassium chromate (K2CrO4) and sodium arsenite (NaAsO2)] were studied. The overall rate of polymerization was proportional to √[K2CrO4] × [NaAsO2], and the energy of activation was approximately 10.5 kJ/mol. Polyacrylonitrile was recovered as a coagulum in the medium. The formation of polyacrylonitrile was confirmed with Fourier transform infrared and 1H‐NMR analyses. Scanning electron microscopy analysis of the polymer revealed the formation of aggregates of polymer particles (3–67 nm). Thermogravimetric studies indicated 50% weight loss at 400°C, and dynamic thermal analysis scan studies revealed an exothermic peak at 507°C due to massive oxidative thermal degradation of the polyacrylonitrile backbone. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 276–280, 2005
Electrically modulated transport of diclofenac salts through hydrogels of sodium alginate, carbopol, and their blend polymers
Authors: Agnihotri Sunil A. , Kulkarni Raghavendra V. , Mallikarjuna Nadagouda N. , Kulkarni Padmakar V. , Aminabhavi Tejraj M. 
Published: February 2005

AbstractThe electrically modulated transdermal migration of diclofenac sodium (DS), diclofenac potassium (DP), and diclofenac diethylammonium (DD) drugs from the hydrogels of sodium alginate (NaAlg), carbopol (CP), and blends of NaAlg with CP prepared in 2:1, 2:1.5, and 2:2 ratios was investigated. The release of DS, DP, and DD was investigated through excised rat skin to study the effects of viscosity, pH, and the ionic strength of the receptor medium under the influence of an electrical current in a switch‐on and switch‐off mode. A pulsatile pattern of transport was observed that depended on the presence or absence of an electrical current. Drug transport was dependent on the electrical current, the ionic nature of drugs, and the ionic strength of the diffusion medium. Drug transport followed the sequence DS > DP > DD. A decrease in viscosity and an increase in the pH of the hydrogel were observed when an electrical current was applied. CP was more responsive to an electrical stimulus, but the rate of transport was higher for NaAlg. Increasing the amount of CP in the blends increased the electrical responsiveness. The blend hydrogel with a high CP content showed the highest enhancement in drug transport, whereas the NaAlg hydrogel showed the least. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 301–311, 2005
Preparation, structure, and properties of a novel rectorite/styrene–butadiene copolymer nanocomposite
Authors: Wang Yiqing , Zhang Huifeng , Wu Youping , Yang Jun , Zhang Liqun 
Published: February 2005

AbstractRectorite/styrene–butadiene copolymer (SBR) nanocomposite was prepared by cocoagulating SBR latex and rectorite/water suspension. Transmission electron microscopy showed that the layers of rectorite were well dispersed in the SBR matrix and the aspect ratio (width/thickness) of it was higher than that of montmorillonite (MMT). X‐ray diffraction indicated that the nanocomposite produced by this method was of neither intercalated type nor exfoliated type. The gas barrier properties and mechanical properties of the novel nanocomposites were excellent. The nanocomposites are expected to be candidates for tire tube or inner materials. Rectorite appears to be a promising filler for the nanocomposite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 324–328, 2005
Kinetics and modeling of diethylene glycol bisallyl carbonate bulk polymerization
Authors: Hace Iztok , Golob Janvit , Krajnc Matjaž 
Published: February 2005

AbstractThe free‐radical polymerization kinetics of diethylene glycol bisallyl carbonate in bulk were investigated with Fourier transform infrared and Fourier transform Raman techniques in a wide temperature range of 50–140°C with four different peroxide initiators. In addition, the ratios of the degradative kinetic rate constant to the propagation rate constant under different reaction conditions were obtained from molecular weight measurements under various reaction conditions. The ratio of the chemically controlled termination and propagation rate constants of the polymerization system were obtained with the initial rates of polymerization and the number‐average molecular weight data, which were between 8.22 × 10−5 and 1.47 × 10−3 L mol−1 s−1. The initiator efficiencies were evaluated with special experiments at low initiator concentrations with the theory of dead‐end polymerization. The computed conversions from the developed kinetic model were in good agreement with the conversion and molecular weight measured data. The values of the diffusion‐controlled propagation and termination rate constants, with clear and physical meaning, were the only two parameters obtained from the developed kinetic model fitting the measured conversion points. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 345–357, 2005
Synthesis and characterization of side‐chain liquid‐crystalline polyurethane elastomers
Authors: Wang Tzong‐Liu , Tsai Jung‐Shian , Tseng Ching‐Guey 
Published: February 2005

AbstractSide‐chain liquid‐crystalline (SCLC) polyurethane elastomers with methoxybiphenyl mesogens pendant on the chain extenders were synthesized by the conventional prepolymer technique and condensation reaction. Two SCLC polyurethanes with mesogens having spacers of six and eight methylene units were prepared. The structures of the mesogenic units and SCLC polyurethanes were confirmed by Fourier transform infrared and 1H‐NMR. The polymer properties were also studied with solubility tests, water‐uptake measurements, and inherent‐viscosity measurements. The tensile properties indicated that both SCLC polyurethanes were thermoplastic elastomers. Their phase‐transition temperatures were studied with differential scanning calorimetry. Wide‐angle X‐ray diffraction studies revealed the existence of liquid‐crystalline phases for both SCLC polyurethanes. Polarizing optical microscopy investigations further confirmed the thermotropic liquid‐crystalline behaviors and smectic mesophases of both samples. Thermogravimetric analysis results showed a more rapid degradation in the initial stage and a slower degradation process in the latter stage for both SCLC polymers in comparison with those of the linear starting polyurethane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 336–344, 2005
A temporal comparison of AltaVista Web searching
Authors: Jansen Bernard J. , Spink Amanda , Pedersen Jan 
Published: February 2005

AbstractMajor Web search engines, such as AltaVista, are essential tools in the quest to locate online information. This article reports research that used transaction log analysis to examine the characteristics and changes in AltaVista Web searching that occurred from 1998 to 2002. The research questions we examined are (1) What are the changes in AltaVista Web searching from 1998 to 2002? (2) What are the current characteristics of AltaVista searching, including the duration and frequency of search sessions? (3) What changes in the information needs of AltaVista users occurred between 1998 and 2002? The results of our research show (1) a move toward more interactivity with increases in session and query length, (2) with 70% of session durations at 5 minutes or less, the frequency of interaction is increasing, but it is happening very quickly, and (3) a broadening range of Web searchers' information needs, with the most frequent terms accounting for less than 1% of total term usage. We discuss the implications of these findings for the development of Web search engines.
Clearing up “implicit knowledge”: Implications for Knowledge Management, information science, psychology, and social epistemology
Authors: Day Ronald E. 
Published: February 2005

Abstract“Implicit knowledge” and “tacit knowledge” in Knowledge Management (KM) are important, often synonymous, terms. In KM they often refer to private or personal knowledge that needs to be made public. The original reference of “tacit knowledge” is to the work of the late scientist and philosopher, Michael Polanyi (Polanyi, 1969), but there is substantial evidence that the KM discourse has poorly understood Polanyi's term. Two theoretical problems in Knowledge Management's notion of “implicit knowledge,” which undermine empirical work in this area, are examined. The first problem involves understanding the term “knowledge” according to a folk‐psychology of mental representation to model expression. The second is epistemological and social: understanding Polanyi's term, tacit knowing as a psychological concept instead of as an epistemological problem, in general, and one of social epistemology and of the epistemology of the sciences, in particular. Further, exploring Polanyi's notion of tacit knowing in more detail yields important insights into the role of knowledge in science, including empirical work in information science. This article has two parts: first, there is a discussion of the folk‐psychology model of representation and the need to replace this with a more expressionist model. In the second part, Polanyi's concept of tacit knowledge in relation to the role of analogical thought in expertise is examined. The works of philosophers, particularly Harré and Wittgenstein, are brought to bear on these problems. Conceptual methods play several roles in information science that cannot satisfactorily be performed empirically at all or alone. Among these roles, such methods may examine historical issues, they may critically engage foundational assumptions, and they may deploy new concepts. In this article the last two roles are examined.
Rheological characterization and dissolution kinetics of fibrin gels crosslinked by a microbial transglutaminase
Authors: Sun Yan , Giraudier Olivier , Garde Véronique Larreta 
Published: February 2005

AbstractVarious fibrin gels were prepared with a microbial transglutaminase under miscellaneous conditions. The gels were characterized through their rheological properties. The influence of fibronectin addition and that of covalent bonding on the viscoelastic characteristics were evaluated. Gel elasticity is proportional to fibrinogen concentration but shows a nonlinear dependence on transglutaminase concentration. Additional crosslink of fibronectin in fibrin gels has no effect on the rheological character of the matrix. Dissolution kinetics in concentrated urea solutions evidences the role of covalent bonds on gel stability. The rheological properties and gel stability are discussed in relation with the enzyme‐catalyzed covalent bonding. The microbial enzyme reactions are compared to those of FXIII and tissue transglutaminases. © 2005 Wiley Periodicals, Inc. Biopolymers, 2005
The structure of “unstructured” regions in peptides and proteins: Role of the polyproline II helix in protein folding and recognition*
Authors: Rath Arianna , Davidson Alan R. , Deber Charles M. 
Published: February 2005

AbstractClassical descriptions of the three‐dimensional shapes of proteins usually invoke three main structures: α‐helix, β‐sheet, and β‐turn. More recently, the polyproline II (PPII) structure has been implicated in diverse biological activities including signal transduction, transcription, cell motility, and immune response. Concurrently, evidence is accumulating that PPII structure has a significant role in the unfolded states of proteins. In this article, we connect the structural properties of PPII helices to their roles in protein recognition and protein unfolded states. The properties unique to the PPII conformation are linked to the exploitation of this structure for the molecular recognition of proteins, using peptide ligands of the Src homology 3 (SH3) domain as an example. The evidence supporting a role for PPII conformation in protein‐unfolded states is also presented in the context of the forces that may stabilize the PPII conformation in unfolded polypeptides. © Wiley Periodicals Inc. Biopolymers (Pept Sci), 2005
Artificial diiron proteins: From structure to function
Authors: Calhoun Jennifer R. , Nastri Flavia , Maglio Ornella , Pavone Vincenzo , Lombardi Angela , DeGrado William F. 
Published: February 2005

AbstractDe novo protein design provides an attractive approach for the construction of models to probe the features required for the function of complex metalloproteins. These minimal models contain the essential elements believed necessary for activity of the protein. In this article, we summarize the design, structure determination, and functional properties of a family of artificial diiron proteins. © 2005 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2005
Ring‐Opening Protonolysis of Sila[1]ferrocenophanes as a Route to Stabilized Silylium Ions
Authors: Bourke Sara C. , MacLachlan Mark J. , Lough Alan J. , Manners Ian 
Published: February 2005

AbstractThe ring‐opening reactions of a series of sila[1]ferrocenophanes with protic acids of anions with various degrees of noncoordinating character have been explored. Ferrocenyl‐substituted silyl triflates FcSiMe2OTf (5 a) and Fc3SiOTf (5 b) (Fc=(η5‐C5H4)Fe(η5‐C5H5)) were synthesized by means of HOTf‐induced ring‐opening protonolysis of strained sila[1]ferrocenophanes fcSiMe2 (3 a) and fcSiFc2 (3 b) (fc=(η5‐C5H4)2Fe). Reaction of 3 a and 3 b with HBF4 yielded fluorosubstituted ferrocenylsilanes FcSiMe2F (6 a) and Fc3SiF (6 b) and suggested the intermediacy of a highly reactive silylium ion capable of abstracting F− from the [BF4]− ion. Generation of the solvated silylium ions [FcSiMe2⋅THF]+ (7a+), [Fc3Si⋅THF]+ (7b+) and [FcSiiPr2⋅OEt2]+ (7c+) at low temperatures, by reaction of the corresponding sila[1]ferrocenophanes (3 a, 3 b, and fcSiiPr2 (3 c), respectively) with H(OEt2)(S)TFPB (S=Et2O or THF; TFPB=tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate) was monitored by using low‐temperature 1H, 13C, and 29Si NMR spectroscopy. In situ reaction of 7a+, 7b+, and 7c+ with excess pyridine generated [FcSiMe2⋅py]+ (8a+), [Fc3Si⋅py]+ (8b+), and [FcSiiPr2⋅py]+ (8c+), respectively, as observed by 1H, 13C, and 29Si NMR spectroscopy. A preparative‐scale reaction of 3 b with H(OEt2)(THF)TFPB at −60 °C and subsequent addition of excess pyridine gave isolable red crystals of 8b‐[TFPB]⋅CHCl3, which were characterized by 1H and 29Si NMR spectroscopy as well as by single‐crystal X‐ray diffraction.