bluuebunny/crossref_metadata_2025 huggingface dataset:
Load Spectrum and Fatigue Life Analysis of the Blade of Horizontal Axis Wind Turbine
Authors: Deyuan Li , Zhiquan Ye , Yan Chen , Nengsheng Bao
Published: April 2004

This tutorial paper presents a load spectrum and an engineering analysis from first principles for estimating the fatigue life of GRP blades of horizontal axis wind turbines. The distributions of aerodynamic loads, which affect the fatigue life of the blade, are analyzed using strip theory. The stiffening effect on a rotating blade is discussed using the multi-body dynamics method. The influences of this dynamic stiffening effect and composite material anisotropy on the blade vibration modes are analyzed. Then, the dynamic stress response caused by the deterministic dynamic loads, such as aerodynamic load, gravitational load and rotating centrifugal load etc, is calculated using finite element modal superposition method. Fatigue damage performance, fatigue damage rule and the fatigue life estimate method for GRP blades are included. Finally, applying the Palmgren Miner rule for linear fatigue damage accumulation, an estimate of safe working life is made. The fatigue life estimate for a 1.5 MW wind turbine GRP blade agrees with physical experience. The paper is presented as a didactic example for the methods used.
Variable-Speed Wind Turbines with Multi-Pole Synchronous Permanent Magnet Generators. Part I: Modelling in Dynamic Simulation Tools
Authors: Akhmatov Vladislav , Nielsen Arne Hejde , Pedersen J Kaas , Nymann Ole
Published: April 2004

Variable-speed wind turbines are a promising concept for large offshore wind farms. The variable-speed concept can be realised with multi-pole synchronous generators (MPSG) excited by permanent magnets. The main advantages of this concept are that (i) the wind turbines are gearless and (ii) the electrical excitation system is replaced by permanent magnets. The electromagnetic construction of the permanent magnet generators (PMG) is, however, more complex than in conventional concept generators. The PMG are grid-connected through and controlled by their frequency converters. The converter control can be used to stabilise the large wind farm at transient events in the grid to complete the grid specifications of the power system controllers. This article gives an overview of the structural concepts of PMG and explains modelling details of the PMG and their frequency converters.
Wind Energy Potential in Karnataka, India
Authors: Ramachandra T.V. , Shruthi B.V.
Published: April 2004

For securing maximum output of power using a given type of wind electric generator, an assessment of the wind resource available at any prospective site is essential. Estimation of wind power potential is based on data of the wind frequency distribution at the site, are collected from official meteorological data. The analyses show that coastal and dry arid zones in Karnataka have good wind potential.
Vertical Axis Wind Rotor with Concentration by Convergent Nozzles
Authors: Shikha  , Bhatti T. S. , Kothari D. P.
Published: April 2004

This Dissertation Note describes practical tests on small vertical axis turbines using concentrating convergent nozzles. The nozzles amplify the wind-speed before the air contacts the blades. The purpose of the work relates to distributed power generation in regions with weak, mainly single-directional winds. Wind-tunnel tests of five different nozzle arrangements have been conducted. The length and outlet area of the nozzles were changed to see the effect on the increase of wind speed. The variation of the output wind-speed with different values of input wind speed, different input areas of nozzle and different lengths of nozzle have been recorded. The tests identify the optimum nozzle dimensions for improved performance of the system.
Quantitative Surface Analysis of Urban Airborne Particles by X‐Ray Photoelectron Spectroscopy
Authors: Atzei Davide , Rossi Antonella
Published: April 2004

X‐ray photoelectron spectroscopy (XPS) has been used to determine the species present in urban particulate matter collected in the city of Cagliari (Sardinia, Italy) and in an industrial area near to Cagliari. Samples were collected on both cellulose and glass fiber filters. Elemental identification, chemical state and quantitative analyses of the examined samples indicated the presence of Na3AlF6, SiO2 and Al2O3 in the ratio 2:2:5, carbon and oxygen being the major components. The results obtained on NIST SRM 1648 urban particulate matter, before and after grinding, are also presented.
Evaluation of a Fibre Optic Device in Solution Equilibria Studies. Application to 3‐Hydroxybenzoic Acid Ionization
Authors: Crisponi Guido , Caredda Alessandra , Cristiani Franco , Diaz Angelo , Nurchi Valeria Marina , Pinna Rosalba , Pivetta Tiziana , Silvagni Roberta
Published: April 2004

The use of a fibre optic device for spectrophotometric measurements in solution equilibria studies is presented. In particular the precision obtainable with such equipment is evaluated as a function of different experimental conditions, such as path length, averaging time and stirring of the solution. Analysis of 3‐hydroxybenzoic acid ionization is presented to assess the results obtained in the study of an equilibrium system.
A Study of the Dielectric Behaviour and the Liquid Structure of a Ternary Solvent System
Authors: Cocchi Marina , Franchini GianCarlo , Marchetti Andrea , Pigani Laura , Seeber Renato , Tassi Lorenzo , Ulrici Alessandro , Zanardi Chiara , Zannini Paolo
Published: April 2004

The static dielectric constant of the {DMF(1) + ME(2) + DME(3)} ternary mixtures was measured as a function of temperature (25 ≤ t/°C ≤ 80) and composition, over the whole mole fraction range 0 ≤ x1, x2, x3 ≤ 1. The experimental values were processed by an empirical equation accounting for the dependence ϵ = ϵ(T, ϕi;), where ϕı is the volume fraction of the components. A comparison between calculated and experimental data shows that this fitting relationship can be effectively employed to predict ϵ values in correspondence to experimental data gaps. Starting from the experimental measurements, some derived quantities such as molar polarisation (P), and excess counterpart (PE) were obtained. Both the excess properties, ϵE and PE, take values partly positive and partly negative under all experimental conditions. The values of the excess quantities are indicative of the presence of specific interactions among different components in the mixtures.
Identification and Semi‐Quantitative Determination of Gum Arabic in Wines by GC‐MS and Size Exclusion Chromatography
Authors: Gallina Albino , Fiorese Elisa , Pastore Paolo , Magno Franco
Published: April 2004

A method for the identification and the semi‐quantitative determination of the food additive gum Arabic in wines is described. Tests carried out on solutions spiked with known amounts of wine and gum Arabic polysaccharides allowed to define the suitable conditions for their quantitative precipitation and size exclusion analysis. CG‐MS analyses of the different recovered fractions allowed to discriminate between gum Arabic and wine polysaccharides through the identification of glucose and mannose present only in wine polysaccharides. The proposed method was based on the wine polysaccharides free peak area obtained by size exclusion chromatography. The same cut‐off time was always used both in the preparation of the calibration plot and in the analysis of the real samples. Gum Arabic was determined in a ratio of 1/10 w/w with wine polysaccharides with a detection limit of 0.074 mg ml‐1 which is lower than the lowest gum Arabic amount usually added into wines. Owing to the moderately low natural variability of the gum Arabic standards the described procedure is suitable for a semi‐quantitative analysis even if its accuracy allowed a quite reliable determination of the gum Arabic amount usually added to wine.
Working without Accumulation Membrane in Flow Fieldflow Fractionation. Effect of Sample Loading on Retention
Authors: Melucci Dora , Zattoni Andrea , Casolari Sonia , Reggiani Matteo , Sanz Ramses , Reschiglian Pierluigi , Torsi Giancarlo
Published: April 2004

Membraneless hyperlayer flow field‐flow fractionation (Hyp FlFFF) has shown improved performance with respect to Hyp FlFFF with membrane. The conditions for high recovery and recovery independent of sample loading in membraneless Hyp FlFFF have been previously determined. The effect of sample loading should be also investigated in order to optimize the form of the peaks for real samples. The effect of sample loading on peak retention parameters is of prime importance in applications such as the conversion of peaks into particle size distributions. In this paper, a systematic experimental work is performed in order to study the effect of sample loading on retention parameters. A procedure to regenerate the frit operating as accumulation wall is described. High reproducibility is obtained with low system conditioning time.
Analytical Characterization of Poly(Pyrrole‐3‐Carboxylic Acid) Films Electrosynthesised on Pt, Ti and Ti/Al/V Substrates
Authors: De Giglio Elvira , Losito Ilario , Dagostino Francesco , Sabbatini Luigia , Zambonin Pier Giorgio , Torrisi Alberto , Licciardello Antonino
Published: April 2004

With the aim of developing a polymeric multilayer film for application in advanced biomaterials, as a first step poly(pyrrole‐3‐carboxylic acid) films (abbreviated as PPy‐3‐carbox) were electropolymerised from pyrrole‐3‐carboxylic acid solutions by cyclic voltammetry and chronoamperometry on platinum, titanium and Ti90Al6V4 substrates and characterised both electrochemically (cyclic voltammetry) and spectroscopically (X‐Ray Photoelectron Spectroscopy, XPS). Electrochemical experiments showed that the potential range adopted for electropolymerization affects the polymer electroactivity, by analogy with unsubstituted polypyrrole. The combination of conventional and chemical derivation‐ XPS provided information on PPy‐3‐carbox surface structure, showing no significant difference between films grown on different substrates and an increase of the COOH groups amount (one group over three pyrrole rings, as an average) with respect to unsubstituted polypyrrole (PPy), as expected. Finally, a preliminary Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) investigation was performed in order to get further information on the polymer structure and electroactivity.
Complexes of Copper(II) with Adenosine or Guanosine Nucleosides, Nucleotides 5'‐Monophosphate, 2'‐Deoxynucleosides or 2'‐Deoxynucleotides 5'‐Monophosphate in Aqueous Solution
Authors: Daniele Pier G. , Prenesti Enrico , Berto Silvia , Zelano Vincenzo , Aruga Roberto
Published: April 2004

In this paper copper(II) complex formation in aqueous solution with a series of nucleosides (adenosine or guanosine) or nucleotides 5'‐monophosphate is studied by means of potentiometry, visible spectrophotometry and ultraviolet circular dichroism. A chemical model has been formulated for each binary system (at T = 25 °C and I = 0.1 M), with particular attention to the interaction in the basic field. A spectrum (both visible absorption and ultraviolet circular dichroism) for each complex with a significant percentage of formation (in the adopted experimental conditions) has been calculated, allowing structural details to be hypothesised. The interaction with deprotonated alcoholic group(s) of the ribose moiety has been found to be fundamental in determining the co‐ordination chemistry of each ligand considered while cases of co‐operation between the purine and ribose donor(s) were also considered. Confirmations were also obtained by an investigation on the corresponding 2'‐deoxy compounds as ligands.
The Formal Redox Potential of the Yb(III, II) Couple at 0 °C in 3.22 Molal NaCl Medium
Authors: Amorello Diana , Romano Vincenzo , Zingales Roberto
Published: April 2004

Following our previous investigations on aqueous solutions of hypooxidized and iperoxidized species, we managed, by lowering the temperature of the solutions to 0 °C, to obtain, by electrochemical methods, Yb(II) and Yb(III) mixtures, enough stable to determine by a potentiometric method the formal redox potential of the Yb(III, II) couple. Its value, in a large range of total Ytterbium concentration, is − 1233 ± 3 mV against the molal hydrogen electrode in the 3.22 m NaCl medium.
Polycyclic Aromatic Hydrocarbons in the Atmosphere: Monitoring, Sources, Sinks and Fate. II: Sinks and Fate
Authors: Vione Davide , Barra Silvia , de Gennaro Gianluigi , de Rienzo Massimo , Gilardoni Stefania , Perrone Maria Grazia , Pozzoli Luca
Published: April 2004

This paper reviews the transformation processes that polycyclic aromatic hydrocarbons (PAHs) undergo in the atmosphere. These processes can take place both in the gas phase and in the particulate/aerosol one. Among the gas‐phase processes, the most important ones are the daytime reaction with •OH and the nighttime reaction with •NO3. The relative importance of the two processes depends on the particular PAH molecule. For instance, gaseous naphthalene is mainly removed from the atmosphere upon reaction with •OH, while gaseous phenanthrene is mainly removed by reaction with •NO3. Oxy‐, hydroxy‐, and nitro‐PAHs are the main transformation intermediates. Reaction with ozone and photolysis play a secondary role in the transformation of gaseous PAHs. The particle‐associated processes are usually slower than the gas‐phase ones, thus the gas‐phase PAHs usually have shorter atmospheric lifetimes than those found on particulate. Due to the higher residence time on particulate when compared with the gas phase, direct or assisted photolysis plays a relevant role in the transformation of particle‐associated PAHs. Among the other processes taking place in the condensed phase, nitration plays a very important role due to the health impact of nitro‐PAHs, some of them being the most powerful mutagens found so far in atmospheric particulate extracts.
Evaluation of Purification Procedures of DNA from Maize‐Meal Samples by Exploiting Different Analytical Techniques for the Assessment of DNA Quality
Authors: Vanni Adriano , Anfossi Laura , Giovannoli Cristina , Oddenino Leila , Giraudi Gianfranco
Published: April 2004

Two different approaches generally applied to achieve purification of DNA extracted from cells were compared: precipitation by organic solvents and enzymatic treatments. We investigated various experimental protocols reported in literature by evaluating DNA purity, integrity and yield. Reliability of analytical techniques normally employed to assess DNA purity and quantity was studied and comments and conclusions were suggested by comparing results obtained by different analytical techniques. Enzymatic treatments prove to be unable of increasing DNA purity while determining a significant degradation. In contrast, optimised conditions for solvent precipitation enabled a sharp increase of DNA purity to be obtained, associated with the maintenance of the initial DNA integrity. The application of the optimised protocol to maize‐meal samples allowed us to achieve a good PCR amplification even with those samples which gave poor amplification by following the protocol recommended by the Italian legislation in force for GMO detection in food.
Characterization of n‐Alkanes and PAHS in PM10 Samples in Prato (Italy)
Authors: Cincinelli Alessandra , Stefani Andrea , Seniori Costantini Stefano , Lepri Luciano
Published: April 2004

This study reports the characterization of n‐alkanes and PAHs in 13 PM10 samples collected in the South area of Prato (Italy) during the period April‐July 2002. n‐Alkanes concentrations ranged between 9, 45 and 182, 64 ng/mc while PAHs concentrations ranged from 3, 058 to 22, 048 ng/mc. No correlation was evidenced between benzo(a)pirene and PM10 concentrations. Total carbonaceous aerosol was also measured and it meanly accounted for 21, 5% of the PM10 mass ranging from 12, 4% to 27, 1%.
The Acidic Constants of 2‐Hydroxybenzohydroxamic Acid in NaClO4 Solutions at 25°C
Authors: Ciavatta Liberato , de Tommaso Gaetano , Iuliano Mauro
Published: April 2004

The protolysis equilibria of 2‐hydroxybenzohydroxamic acid, H2SAX, have been studied at 25°C in different ionic media by potentiometric titration with a glass electrode. The media were 0.513, 1.05, 2.21 and 3.5 mol/kg NaClO4. The constants β‐p(H2SAX⇌ H2‐pSAX‐p+pH+), combined with salting effects of NaClO4 on H2SAX deduced from solubility determinations, were processed by the specific interaction theory, SIT, to give equilibrium constants at infinite dilution, log β‐1° = ‐ 7.655±0.013 and log β‐2° = ‐17.94±0.04, as well as specific interaction coefficients b(HSAX‐, Na+) = 0.12±0.01 and b(SAX2‐, Na+) = 0.17±0.02, molal‐1.
Effect of a Contaminated Site (The San Giuliano Landfill, Venice, Italy) on the Interaction between Water Bodies in a Coastal Aquifer System
Authors: Critto Andrea , Zuppi Giovanni Maria , Carlon Claudio , Marcomini Antonio
Published: April 2004

A complex multiple aquifer system affected by a contaminated site and exposed to tidal effects was investigated to develop the hydrogeological conceptual model of the study case. Two water bodies were identified, from top to down: a surface aquifer unaffected by tidal events, and a semiconfined aquifer partly communicating with the brackish lagoon waters. By using the Cl‐/SO42‐ ratio and the DOC (Dissolved Organic Carbon) concentration, as well as by applying the kriking to the piezometric levels results, the groundwater flow directions and the hydraulic gradients within the investigated aquifers were also identified. Based on the overall results, a schematic of the conceptual model for the whole aquifer system was provided which allows to visualize the communication between the different water bodies.
Application of Voltammetric Methods for the Analysis of Gold and Other Transition Metals in Quartzite Rock
Authors: Tamrakar Praveen Kumar , Pitre Krishna Sadashiv
Published: April 2004

Simple, rapid and accurate voltammetric methods viz. DCP, DPP and DPASV have been presented for the trace determination of gold and other transition metals in quartzite rock sample. The analysis has been performed using 0.1M(NH4)2 tartrate, 0.1M NaClO4 and 1M NaOH as supporting electrolyte with 0.001 % gelatin as maximum suppressor. The results show the presence of CuII(10.70), CoII(4.72), FeIII(66.96), AuIII(0.066), ZnII(1.68) and CdII(0.62) mg.g‐1 metal ions from the sample. Gold produced a well defined wave/peak with E1/2/EP = ‐0.61V/‐0.64V vs SCE, in 1M NaOH supporting electrolyte. The quantitative analysis of metal inos was carried out by the method of standard addition. Statistical treatment of the observed voltammetric data reveals high accuracy and good precision of determination. The observed voltammetric results are comparable with those obtained using AAS method.
Extraction of Electrolytes from Aqueous Solutions and Their Spectrophotometric Determination by Use of Acid‐Base Chromoionophores in Lipophylic Solvents
Authors: Barberi Paola , Giannetto Marco , Mori Giovanni
Published: April 2004

The formation of non‐absorbing complexes in an organic phase has been exploited for the spectrophotometric determination of ionic analytes in aqueous solutions. The method is based on liquid‐liquid extraction of aqueous solution with lipophylic organic phases containing an acid‐base chromoionophore, a neutral lypophilic ligand (neutral carrier) selective to the analyte and a cationic (or anionic) exchanger. The method avoids all difficulties of the preparation of the very thin membranes used in optodes, so that it can advantageously be used for the study of the role physical‐chemical parameters of the system in order to optimize them and to prepare, if necessary, an optimized optode. Two lipophylic derivatives of Nile Blue and 4', 5‐dibromofluorescein have been synthesized, in order to ensure their permanence within organic phase. Two different neutral carriers previously characterized by us as ionophores for liquid‐membrane Ion Selective Electrodes have been employed. Three different ionic exchangers have been tested. Furthermore, a model allowing the interpolation of experimental data and the determination of the thermodynamic constant of the ionic‐exchange equilibrium has been developed and applied.
Adjustments in the South Korean beef import market under beef import liberalization policies
Authors: Kim Renee B. , Kim Y.J. , Veeman Michele
Published: April 2004

This report analyzes the implications for exporters of the policy of gradual liberalization of beef importation that preceded the phasing out of state trader importation in the South Korean beef market. The process of beef trade liberalization involved successive increases in import quota, and the allocation of this, through a simultaneous buy‐sell system (SBS), to increasing numbers of licensed Korean importing firms, for several years prior to January 1, 2001. At that time, state trading was entirely replaced by private sector importation. During the period of policy adjustment of beef importation, licensed importing firms, known as “supergroups” (i.e., SBS firms), acted as designated SBS import beef traders for groups of end‐use businesses. The importation of beef is analyzed based on a model of the import behavior of the SBS firms for the period 1995 through 2000. The econometric model focuses on the source preferences of importers; the results suggest the importance of alliances of importers with various beef exporters. Model simulations suggest that with further import growth, the United States is likely to remain a major player in the Korean import beef market and that Australia may also gain from growth in this market. [EconLit citations: F14, L19, L66.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 201–216, 2004.
Primary agricultural product demand in post‐communist Russia
Authors: Shiptsova Rimma , Goodwin H.L. , Holcomb Rodney
Published: April 2004

This study examines food consumption patterns for households in Siberian Russia. The study is based on a survey conducted by the American Business Center in Vladivostok in February/March 1996. When incomes grow, households tend to include greater proportions of livestock products in their diets. That leads to a corresponding increase in indirect cereal consumption. Alternative measures of food consumption employed in the analysis are expenditures and calories. The results show that the expenditure income elasticity of cereal products is positive whereas income elasticities of cereal products are zero for calorie measures, implying demand for service from non‐agricultural sectors. The elasticities of total food and animal product consumption are positive for both measures. Stabilization of transition economies might lead to a substantial increase in indirect cereal consumption, which, in turn, would lead to a dramatic increase in demand for agricultural imports. [EconLit citations: L660, D120, Q180.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 129–141, 2004.
Advertising's effect on the market demand elasticity: A note
Authors: Kinnucan Henry W. , Zheng Yuqing
Published: April 2004

Using a simple market model and Frisch's duality relation, this report develops propositions about the relationship between advertising and the market demand elasticity that may prove useful in empirical research. In particular, we find that a parallel shift in a linear demand function always alters the market demand elasticity unless supply is unitary elastic. However, the elasticity change in most cases will be negligible. We also find that curve rotation does not imply that the demand elasticity has changed, and vice versa. Lastly, if the price level affects advertising's ability to shift the market demand curve, it must also be true that advertising affects the demand elasticity. The converse is also true, i.e., if advertising affects the demand elasticity, the price level must affect advertising's ability to shift the demand curve. [JEL citations: Q130, Q170, Q180.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 181–188, 2004.
Risk‐learning process in forming willingness‐to‐pay for egg safety
Authors: Maruyama Atsushi , Kikuchi Masao
Published: April 2004

Using data obtained from a mail survey on consumers' willingness‐to‐pay (WTP) and risk beliefs for reducing the risk of salmonella contamination of eggs, we have examined the risk‐learning process through which individuals form their WTP. The results of estimation of the WTP function support the hypothesis that respondents follow an adaptive learning process, in which they establish their posterior risk belief in a rational manner by adapting their prior risk belief as they are supplied with new risk information. We find that the weight of the prior risk belief is slightly smaller than that of new risk information in forming the posterior risk belief for three out of four estimation models. Knowledge of how consumers form their risk beliefs and who evaluates egg safety enables us to clearly specify targets for effective campaigns to enhance public awareness at a household level about health and food safety issues. [EconLit citations: D120, Q260.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 167–179, 2004.
Mass‐transfer enhancement in a wavy‐walled tube by imposed fluid oscillation
Authors: Nishimura T. , Bian Y. N. , Kunitsugu K.
Published: April 2004

The present experimental study deals with mass‐transfer enhancement and fluid dynamic behavior in a wavy‐walled tube for pulsatile flow. Three flow parameters are considered here: the net flow Reynolds number, the oscillatory fraction of the flow rate, and the Strouhal number. Among them, we especially focused on the effect of Strouhal number on mass‐transfer enhancement under the condition of no reverse flow. Time‐averaged transport enhancement by means of imposed fluid oscillation is found to vary with the net flow Reynolds number and with the oscillatory fraction of the flow rate. The most effective mass‐transfer enhancement is registered when the net flow falls on just before the transitional flow regime for steady flow. Furthermore, there is an optimum Strouhal number, corresponding to the maximum transport enhancement, that depends on the oscillatory fraction of the flow rate. The results of time variation for flow behavior show that stable and unstable flow states exist during one oscillation cycle. The duration of the unstable flow state, corresponding to the optimum Strouhal number, is found to be the longest, and it leads to a remarkable fluid exchange between the mainstream and the recirculation zone, thus contributing to the mass transfer enhancement. These results indicate that the transport enhancement mechanism for the wavy‐walled tube is quite different from the resonant transport enhancement observed in the two‐dimensional (2‐D) wavy‐walled channel. © 2004 American Institute of Chemical Engineers AIChE J, 50: 762‐770, 2004
Crosslinking reaction of polyacrylate soap‐free hydrosol with zirconium chelate
Authors: Huang Zhihong , Xie Zhiming , Li Zhuomei
Published: April 2004

The crosslinking reaction mechanism of polyacrylate copolymer (monomer mass ratio of methyl methacrylate/butyl acrylate/acrylic acid = 48.77:46.69:4.54) hydrosol with triethanolamine chelate of zirconium isopropyloxide was studied with IR spectroscopy, NMR spectroscopy, differential scanning calorimetry, and ultraviolet spectroscopy. The instrumental analyses on the copolymer mixture heated at different temperatures were investigated, and we proved that the crosslinking adduct had amino groups that were provided by the chelate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3605–3609, 2004
Enzymatically degradable and pH‐sensitive hydrogels for colon‐targeted oral drug delivery. I. Synthesis and characterization
Authors: Bajpai S. K. , Saxena Sutanjay
Published: April 2004

Cylindrical hydrogels, composed of starch and poly(acrylic acid), were synthesized, and their swelling behavior was studied as a function of the pH of the medium. The gels underwent a sharp transition from Fickian swelling behavior (swelling exponent n = 0.30) to non‐Fickian swelling behavior (n = 0.96) as the pH of the swelling medium changed from 2.0 to 7.4. The hydrogels also underwent partial enzymatic degradation in an amylase‐containing medium of pH 7.4 at 37°C. The effects of the enzyme concentration in the swelling media, the amount of starch present in the gel, the initial water content, the degree of crosslinking, and the diameter of cylindrical hydrogels on the degradation behavior were studied. The degradation of the gels followed Michaelis–Menten kinetics, and the value of the Menten constant was 41.62 × 10−2. The gels exhibited minimum swelling in an acidic pH medium through the formation of a complex hydrogen‐bonded structure and underwent enzymatic degradation in a medium of pH 7.4 (i.e., simulating intestinal fluid) along with chain‐relaxation‐controlled swelling. Therefore, the gels have potential for colon‐targeted drug delivery. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3630–3643, 2004
Cellulose acetate–poly(ether sulfone) blend ultrafiltration membranes. II. Application studies
Authors: Mahendran R. , Malaisamy R. , Arthanareeswaran G. , Mohan D.
Published: April 2004

Ultrafiltration membranes are largely applied as macromolecular solutes and heavy‐metal‐ion separation from aqueous streams. Cellulose acetate and poly(ether sulfone) blend ultrafiltration membranes were prepared by the precipitation phase‐inversion technique in 100/0, 95/5, 85/15, and 75/25% polymer blend compositions in the absence and presence of a polymeric additive, poly(ethylene glycol) 600, at different additive concentrations and were used for the rejection of proteins trypsin, pepsin, egg albumin, and bovine serum albumin; a maximum of 94% rejection was achieved. The toxic heavy metal ions copper, nickel, and cadmium from dilute aqueous solutions were subjected to rejection by the blend membranes by complexation of the ions with the water‐soluble polymeric ligand, polyethyleneimine (PEI). Permeate flux studies of proteins and metal ions were performed simultaneously with the rejection experiments. The atomic absorption spectra results reveal maximum rejection for copper complex and a minimum rejection of about 60% for the cadmium complex. The rejection and permeate flux of the blend membranes were compared with those of pure cellulose acetate membranes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3659–3665, 2004
Superabsorbent polymeric materials. XI. Effect of nonionic monomers on the swelling behavior of crosslinked poly(sodium acrylate‐co‐nonionic monomers) in aqueous salt solutions
Authors: Lee Wen‐Fu , Yang Lin‐Gi
Published: April 2004

A series of xerogels based on sodium acrylate, nonionic monomers such as 2‐hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) methacrylate (PEGMA), and N,N′‐methylene bisacrylamide were prepared by inverse suspension polymerization. The results indicate that the water absorbencies for these two gel series were effectively improved by the addition of a small amount of nonionic monomer (HEMA or PEGMA). The initial absorption rates in deionized water were faster for the PEGMA gels than for the HEMA gels. Scanning electron microscopy showed that the spherical particle size was smaller for the PEGMA gels than for the HEMA gels. In addition, the water absorbency of the gels in various salt solutions decreased with increasing ionic strength, especially for the multivalent salt solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3666–3674, 2004
Chromatographic performance of monodisperse macroporous particles produced by modified seeded polymerization. II. The effect of the diluent/seed‐latex ratio
Authors: Camli S. T. , Unsal E. , Senel S. , Tuncel A.
Published: April 2004

Poly(styrene‐co‐divinylbenzene)‐based monodisperse macroporous particles were obtained by a modified seeded polymerization technique. The monodisperse polystyrene particles, obtained by dispersion polymerization in sufficiently large sizes and with suitable average molecular weights, were directly used as the seed latex in the production of macroporous particles. Therefore, the number of swelling and polymerization stages in the multistage production was reduced. In the first stage, the seed particles were swollen with a diluent, dibutyl phthalate (DBP), and then with a monomer phase including styrene, divinylbenzene, and, as an initiator, benzoyl peroxide. The monodisperse macroporous particles were obtained by the repolymerization of the monomer mixture in the seed particles. The particles, having different porosity characteristics, were synthesized through variations in the dibutyl phthalate/seed‐latex (DBP/SL) ratio. Selected macroporous particle samples were slurry‐packed into stainless steel high‐performance liquid chromatography columns (300 mm long × 7.8‐mm i.d.). The separation of the protein mixture by these columns in the reversed‐phase chromatography (RPC) mode was investigated. Liquid chromatograms with high resolutions were obtained under an acetonitrile/water gradient over a wide range of flow rates (i.e., 0.5–3 mL/min), especially for the particles produced with a monomer/seed‐latex (M/SL) ratio of 3.0 mL/g. In the RPC experiments, the particles produced with an M/SL ratio of 3.0 mL/g and DBP/SL ratios of 1.0 and 1.5 mL/g exhibited better chromatographic performance than the other samples. The maximum theoretical plate number was 3500 for the particles produced with the M/SL ratio of 3.0 mL/g and DBP/SL ratio of 1.5 mL/g with albumin as the analyte. The size exclusion chromatography (SEC) calibration curves and the back‐pressure/flow‐rate relationships of the produced columns were also determined. The particles obtained with an M/SL ratio of 3.0 mL/g and a DBP/SL ratio of 1.5 mL/g exhibited the best performance in SEC applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3685–3696, 2004
Surface modification of single‐walled carbon nanotubes with polyethylene via in situ Ziegler–Natta polymerization
Authors: Tong Xin , Liu Chang , Cheng Hui‐Ming , Zhao Haichao , Yang Feng , Zhang Xuequan
Published: April 2004

Single‐walled carbon nanotubes (SWNTs) were modified with polyethylene (PE) prepared by in situ Ziegler–Natta polymerization. Because of the catalyst pretreated on the surface of the SWNTs, the ethylene was expected to polymerize there. Scanning electron microscopy images and solubility measurements showed that the surface of the SWNTs was covered with a PE layer, and a crosslink may have formed between the SWNTs and PE. When the SWNTs covered with a PE layer were mixed with commercialized PE by melt blending, the resulting composite had better mechanical properties than the composite from the SWNTs without a PE layer. The yield strength, the tensile strength and modulus, the strain at break, and the fracture energy of the modified‐SWNT/PE composites were improved by 25, 15.2, 25.4, 21, and 38% in comparison with those of the raw‐SWNT/PE composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3697–3700, 2004
Bonding properties of epoxy resins containing two mesogenic groups
Authors: Ochi Mitsukazu , Hori Daisuke , Watanabe Yutaka , Takashima Hiroshige , Harada Miyuki
Published: April 2004

Liquid‐crystalline epoxy resins, with introduced aliphatic chains between two mesogenic groups, were synthesized and their adhesive bonding properties were compared to those of the bisphenol‐A–type epoxy resin and the liquid‐crystalline epoxy resin, previously reported. The bonding strength of the former resin system was higher than that of the two later systems. We suggest that the high bonding strength of the twin mesogenic epoxy resins, cured with an aromatic amine, was attributable to the large plastic deformation of the adhesive layer in the fracturing process. We also investigated the effects of the aliphatic chain length in the twin mesogenic epoxy resin on their dynamic mechanical and bonding properties. The bonding strength of the cured twin mesogenic epoxy resins increased with an increase in the aliphatic chain length. We suggest that the high bonding strength of the system introduced by the long aliphatic chain was attributable to the large plastic deformation of the adhesive layer because of the higher network mobility. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3721–3729, 2004
New side‐chain nematic liquid crystalline elastomers containing smectic crosslinking units
Authors: Guan Yan , Yu Yan , Zhang Bao‐Yan , Zhang Li‐Feng
Published: April 2004

A series of siloxane‐based liquid crystalline elastomers containing the smectic crosslinking agent M‐1 and nematic monomer M‐2 were synthesized by a one‐step hydrosilication reaction. The chemical structures of the monomers and polymers obtained were confirmed by FTIR spectroscopy. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X‐ray diffraction (XRD) measurements. The influence of the crosslinking unit on the phase behavior was discussed. The experimental results demonstrated that the glass transition temperatures of elastomers had no remarkable change, and isotropization temperatures decrease with increasing the content of the crosslinking agent M‐1. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3755–3760, 2004
Increased prevalence of semaphorin 3C, a repellent of sympathetic nerve fibers, in the synovial tissue of patients with rheumatoid arthritis
Authors: Miller Luitpold E. , Weidler Claudia , Falk Werner , Angele Peter , Schaumburger Jens , Schölmerich Jürgen , Straub Rainer H.
Published: April 2004

Objective

The presence of selective sympathetic nerve repellents, i.e., semaphorins, may be responsible for the observed reduction of sympathetic innervation in the synovial tissue of patients with rheumatoid arthritis (RA). This study was undertaken to investigate the presence of different semaphorins in synovial tissue of patients with RA, patients with osteoarthritis (OA), and control subjects without inflammation.

Methods

In situ hybridizations with digoxigenin‐labeled RNA probes directed against different semaphorins were performed. The presence of semaphorin 3C (S3C) in the synovial tissue of 10 RA, 10 OA, and 5 control subjects was investigated using a polyclonal antiserum directed against S3C.

Results

All in situ hybridizations revealed the presence of S3C messenger RNA, but no other investigated semaphorin (i.e., against primary afferent sensory nerve fibers), in the synovial tissue of RA and OA patients. Immunohistologic double staining demonstrated that macrophages and fibroblasts were positive for S3C protein. Quantitative analysis of S3C protein staining showed an increased density of S3C‐positive cells in the synovial tissue of RA patients (mean ± SEM 339 ± 65 cells/mm2) in comparison with OA patients (168 ± 27/mm2; P = 0.031 versus RA) and controls (126 ± 26/mm2; P = 0.027 versus RA). Studies of the relationship between sympathetic nerve fiber density and S3C‐positive cell density in the tissue of all patients showed that RA patients generally had lower densities of sympathetic nerve fibers and higher densities of S3C‐positive cells than OA patients and control subjects.

Conclusion

These findings suggest that S3C from macrophages and fibroblasts, which is selectively directed against sympathetic nerve fibers, could be one element responsible for reduced sympathetic innervation in RA tissue. The inability of sympathetic nerve fibers to reinnervate synovial tissue could contribute to the chronic nature of RA.
Circulating endothelial cells as a marker of ongoing vascular disease in systemic sclerosis
Authors: Del Papa Nicoletta , Colombo Gualtiero , Fracchiolla Nicola , Moronetti Lorenza Mazzeo , Ingegnoli Francesca , Maglione Wanda , Comina Denise P. , Vitali Claudio , Fantini Flavio , Cortelezzi Agostino
Published: April 2004

Objective

Circulating endothelial cells (CECs) have been described in different conditions involving vascular injury. Vascular abnormalities play a key role in the pathogenesis of systemic sclerosis (SSc). The aim of this study was to search for the presence of CECs in patients with SSc and to evaluate their clinical associations and possible pathogenic role.

Methods

The study cohort included 46 patients with SSc and 40 healthy controls. Five‐parameter, 3‐color flow cytometry was performed with a FACScan. CECs were defined as CD45 negative, CD34 positive, and P1H12 positive, and activated CECs were defined as CD45 negative and P1H12 positive, CD62 positive, or CD106 positive. Progenitors were identified as CD34 positive and CD133 positive.

Results

Total and activated CEC counts were significantly higher in SSc patients compared with healthy controls and were positively correlated with the disease activity score. With respect to visceral involvement, significant correlation was observed between the CEC number and the severity of pulmonary hypertension. High levels of endothelial progenitors were observed in patients with SSc, and the counts were higher in the early stages of disease.

Conclusion

The presence of CECs in patients with SSc may represent direct evidence of endothelial disease and may be a promising new clinical marker for active SSc. Notably, the association between CECs and pulmonary hypertension and impaired carbon monoxide diffusing capacity was evident in patients with limited cutaneous SSc only, suggesting an important role for CECs in this disease subset with prominent vascular changes. Detection of circulating endothelial progenitors may represent a response to vascular ischemia in early SSc, as an attempt at revascularization.
Slowing of bone loss in patients with rheumatoid arthritis by long‐term high‐intensity exercise: Results of a randomized, controlled trial
Authors: de Jong Zuzana , Munneke Marten , Lems Willem F. , Zwinderman Aeilko H. , Kroon Herman M. , Pauwels Ernest K. J. , Jansen Annemarie , Ronday Karel H. , Dijkmans Ben A. C. , Breedveld Ferdinand C. , Vliet Vlieland Theodora P. M. , Hazes Johanna M. W.
Published: April 2004

Objective

Patients with rheumatoid arthritis (RA) are more at risk for the development of osteoporosis and osteoporotic fractures than are their healthy peers. In this randomized, controlled, multicenter trial, the effectiveness of a 2‐year high‐intensity weight‐bearing exercise program (the Rheumatoid‐Arthritis‐Patients‐In‐Training [RAPIT] program) on bone mineral density (BMD) was compared with usual care physical therapy, and the exercise modalities associated with changes in BMD were determined.

Methods

Three hundred nine patients with RA were assigned to an intervention group, either the RAPIT program or usual care physical therapy. The primary end points were BMD of the hip and spine. The exercise modalities examined were aerobic fitness, muscle strength, and, as a surrogate for those effects not directly measured by the RAPIT program, attendance rate.

Results

The data on the 136 RAPIT participants and 145 usual care participants who completed the study were analyzed. The mean rate of decrease in hip BMD, but not in lumbar spine BMD, was smaller in patients participating in the RAPIT program when compared with that in the usual care group, with a mean decrease of 1.6% (95% confidence interval [95% CI] 0.8–2.5) over the first year and 0.5% (95% CI 1.1–2.0) over the second year. The change in hip BMD was significantly and independently associated with changes in both muscle strength (multivariate odds ratio [OR] 1.75, 95% CI 1.07–2.86) and aerobic fitness (OR 1.79, 95% CI 1.10–2.90), but not with the attendance rate (OR 1.00, 95% CI 0.99–1.00).

Conclusion

A long‐term high‐intensity weight‐bearing exercise program for RA patients is effective in slowing down the loss of BMD at the hip. The exercise modalities associated with this effect are muscle strength and aerobic fitness.
Association of the interleukin‐1 gene cluster with radiographic signs of osteoarthritis of the hip
Authors: Meulenbelt Ingrid , Seymour Albert B. , Nieuwland Marja , Huizinga Tom W. J. , van Duijn Cornelia M. , Slagboom P. Eline
Published: April 2004

Objective

To study the role of the interleukin‐1β gene (IL1B) and the IL‐1 receptor antagonist gene (IL1RN) in relation to the occurrence of radiographic osteoarthritis (ROA) in the hip, knee, and hand and disc degeneration of the spine.

Methods

The study population consisted of a random sample of 886 subjects (ages 55–65 years) from a population‐based cohort (the Rotterdam study). Two polymorphisms within IL1B (3953C>T and −511C>T) and one within IL1RN (the variable‐number tandem repeat [VNTR]) were analyzed and used in an association study of the occurrence of ROA. Haplotyping and simultaneous logistic regression analysis were performed to investigate whether the associations observed were independent.

Results

Associations with a predisposition for hip ROA were observed for heterozygous and homozygous carriers of the rare IL1B allele −511T (crude odds ratio [OR] 1.8, 95% confidence interval [95% CI] 1.0–3.4 and OR 2.9, 95% CI 1.4–6.3, respectively) and of the IL1RN VNTR allele 2 (crude OR 2.0, 95% CI 1.1–3.4 and OR 3.3, 95% CI 1.4–7.8, respectively). An additive effect was observed for carriers of risk alleles of both polymorphisms, with a significant linear‐by‐linear association (P = 0.00022).

Conclusion

Our findings suggest that the IL‐1 gene cluster polymorphisms may play a significant role in the pathogenesis of OA of the hip.
Magnetic resonance imaging of wrist and finger joints in healthy subjects occasionally shows changes resembling erosions and synovitis as seen in rheumatoid arthritis
Authors: Ejbjerg Bo , Narvestad Eva , Rostrup Egill , Szkudlarek Marcin , Jacobsen Søren , Thomsen Henrik S. , Østergaard Mikkel
Published: April 2004

Objective

To explore the presence of changes resembling rheumatoid arthritis erosions and synovitis in metacarpophalangeal (MCP) and wrist joints of healthy individuals on magnetic resonance imaging (MRI) and to compare the MRI findings with conventional radiographic, clinical, and biochemical findings.

Methods

Twenty‐eight healthy individuals were studied. Contrast‐enhanced MRI and conventional radiography of the dominant wrist and second through fifth MCP joints were performed, coupled with standard clinical assessments and biochemical analyses. MR images were evaluated according to the latest OMERACT (Outcome Measures in Rheumatology Clinical Trials) recommendations with respect to synovitis, erosions, and bone marrow edema.

Results

Conventional radiography revealed erosion‐like changes in 1 of 224 MCP joint bones (0.4%) and in 1 of 420 wrist joint bones (0.2%). MRI depicted low‐grade erosion‐like changes in 5 of 224 MCP joint bones (2.2%) and in 7 of 420 wrist joint bones (1.7%), but postcontrast enhancement within the lesion was detected in only 8.3% of these. MRI depicted low‐grade synovitis‐like changes in 10 of 112 MCP joints (8.9%) and in 8 of 84 assessed wrist areas (9.5%), while only minimal early synovial enhancement was detected by dynamic MRI. Three subjects had elevated serum levels of C‐reactive protein, and these subjects displayed 44.5% of the synovitis‐like changes and 41.7% of the erosion‐like changes. Bone marrow edema–like changes were not found in any joints.

Conclusion

Changes resembling mild synovitis or small bone erosions are occasionally found in the MCP and wrist joints of healthy controls. Signs of synovitis on dynamic MRI, enhancement within bone erosion–like changes, and signs of bone marrow edema appear rarely or are absent in healthy controls. These signs may thus prove to be very specific in the distinction between arthritic and normal joints.