bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of chlorinated poly(vinyl chloride)‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membranes and their water permeation properties
Authors: Seok Kang Jong , Hoon Lee Sang , Huh Hoon , Kie Shim Jin , Moo Lee Young
Published: April 2003

Chlorinated poly(vinyl chloride) (CPVC) membranes for microfiltration processes were prepared with the combined process of a solvent evaporation technique and the water‐vapor induced‐phase‐inversion method. CPVC membranes with a mean pore size of 0.7 μm were very hydrophobic. These membranes were subjected to surface modification by ultraviolet (UV)‐assisted graft polymerization with N‐vinyl‐2‐pyrrolidinone (NVP) to increase their surface wettability and decrease their adsorptive fouling. The grafting yields of the modified membranes were controlled by alteration of UV irradiation time and NVP monomer concentration. The changes in chemical structure between the CPVC membrane and the CPVC‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membrane and the variation of the topologies of the modified PVC membranes were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and field emission scanning electron microscopy. According to the results, the graft yield of the modified CPVC membrane reached a maximum at 5 min of UV exposure time and 20 vol % NVP concentration. The filtration behavior of these membranes was investigated with deionized water by a crossflow filtration measurement. The surface hydrophilicity and roughness were easily changed by the grafting of NVP on the surface of the CPVC membrane through a simultaneous irradiation grafting method by UV irradiation. To confirm the effect of grafting for filtration, we compared the unmodified and modified CPVC membranes with respect to their deionized water permeation by using crossflow filtration methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3188–3195, 2003
Vinyl polymerization of norbornene with dinuclear diimine nickel dichloride/MAO
Authors: Mi Xia , Ma Zhi , Cui Nannan , Wang Leyong , Ke Yucai , Hu Youliang
Published: April 2003

Vinyl‐addition polymerization of norbornene was accomplished by two novel dinuclear diimine nickel dichloride complexes in combination with methylaluminoxane (MAO). The activities were moderate. The catalyst structure, Al/Ni molar ratio, solvents, and polymerization temperature all affected the catalytic activities. The obtained polynorbornenes were characterized by 1H‐NMR, 13C‐NMR, FTIR, DSC, WAXD, and intrinsic viscosity measurements. The vinyl‐addition polymers were amorphous but with a short‐range order and high packing density. The polynorbornenes showed glass transition temperatures (Tg) above 240°C and decomposed above 400°C. The catalyst structure and polymerization conditions have effects on the molecular weight and the microstructure of the polymers. The nickel complex with bulkier substituents in the ligand produced polynorbornene with a higher packing density and higher regularity and, therefore, with higher Tg. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3273–3278, 2003
Fracture properties of nanoclay‐filled polypropylene
Authors: Chen Ling , Wong Shing‐Chung , Pisharath Sreekumar
Published: April 2003

Maleic anhydride‐modified polypropylene was compounded with commercially available surface‐modified montmorillonite in a twin‐screw extruder. Recompounding ensured the removal of visible tactoids from the extrudate but TEM and XRD techniques showed nonuniform dispersion of clay platelets. In this study, we investigated the mechanical and fracture properties of nanoclay‐filled polypropylene. Emphasis was placed on the fracture characterization of the clay‐filled polypropylene. Tensile strength and stiffness increased steadily with an increase in the clay loading. The toughness of compounded materials was characterized using rigorous fracture mechanics. J‐integral fracture resistance decreased with an increase in the clay content. The resistance against stable crack growth was compared using the slopes derived from the J–R curve and the tearing modulus concept. A significant amount of crack growth resistance was evident in the nanoclay‐filled polypropylene as opposed to other brittle nanocomposites such as the nylon–clay systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3298–3305, 2003
Ultrasonic and viscometric investigations of a poly(vinyl alcohol)–dextran mixture in aqueous solution
Authors: Sahoo Prafulla K. , Mohapatra Roomky , Sahoo Anusmita , Swain Sarat K.
Published: April 2003

Ultrasonic spectroscopy provided a powerful, efficient, and reliable tool for a number of investigations, including those of polymer solution dynamics, molecular interaction, and the miscibility and compatibility of biopolymers in aqueous solutions. Ultrasonic velocity and related acoustic parameters were measured as a function of the concentration of poly(vinyl alcohol) (PVA), dextran, and a PVA–dextran mixture in water with the resonance method at a frequency of 3 MHz over a temperature range of 20–50°C. From the comparative results of sound velocity, density, adiabatic compressibility, acoustic impedance, and viscosity relaxation time as a function of temperature and concentration, the mode of interaction and the compatibility and miscibility between the two biologically active macromolecules were probed and were considerable at all concentrations and temperatures because of crosslinking via hydrogen bonding involving the hydroxyl groups of both of the biomacromolecules. The interpretations of the acoustic results were confirmed by the intrinsic viscosities of the ternary systems. The significant interaction and compatibility of these biopolymers should lead to the development of pharmaceutically active molecules. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3196–3201, 2003
Effects of lignin as a filler on properties of soy protein plastics. II. Alkaline lignin
Authors: Huang Jin , Zhang Lina , Chen Pu
Published: April 2003

Blend plastics based on soy protein isolate (SPI) strengthened with alkaline lignin (AL) in the weight ratio of 10:0 to 5:5 were prepared with 40 wt % glycerol as a plasticizer by compression molding. The structure and mechanical properties of the blends were investigated by wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamical mechanical thermal analysis (DMTA), and tensile tests. The results indicated that the introduction of AL could effectively increase the tensile strength and Young's modulus, thermal stability, and elongation of the compositive plastics when the AL content ranged from 10 to 20 parts. Moreover, the blend plastics containing 50 parts AL exhibited maximum tensile strength (1.98 MPa) and much higher than that with the SP–AL0 sheet with AL alone (0.89 MPa). In addition, tests of water absorption proved that the introduction of hydrophobic AL effectively reduced water absorption and, hence, decreased water sensibility. Therefore, AL, a relatively low‐cost filler, plays a major role in enhancing the strength and water resistivity of soy protein plastics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3291–3297, 2003
Moderated validity of clinical informant assessment: use in depression and personality
Authors: Kamphuis J. H. , Emmelkamp P. M. G. , de Vries V.
Published: April 2003

Informant assessment or indirect assessment is often a valuable adjunct in clinical practice. Validity of informant assessment has typically been measured as the degree of agreement with self‐report, and has generally been encouraging in both non‐clinical and clinical samples. The present article describes two small‐scale validity studies in an inpatient psychiatric setting and in the community at large, respectively. The first study in a depressed inpatient sample reports on self‐ and informant‐ratings of depressive symptoms, and also examines the moderating influence of informant levels of depression. Results of this study indicate that partners are able to make fairly accurate estimates of the depressed patient's clinical status in terms of depressive symptoms. The second study reports on female participants' personality descriptions of their male partner, and examines to what extent marital distress moderates the agreement. Overall agreement between self‐ and spouse‐ratings of personality traits was satisfactory to high, and the degree of marital distress was not a factor in the accuracy of judgment. Generally, agreement indices were solid and close to test–retest values. Clinical utility and directions for future applications of informant assessment are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
A self‐directed psychosocial intervention with minimal therapist contact for adults with attention deficit hyperactivity disorder
Authors: Stevenson Caroline S. , Stevenson Richard J. , Whitmont Stephanie
Published: April 2003

Using a randomized controlled design, the efficacy of a self‐directed psychosocial intervention with minimal therapist contact, aimed at reducing the symptoms of adult ADHD, was examined. Following the intervention, the treatment group reported significantly reduced ADHD symptomatology; improved organizational skills; improved self esteem and better anger control, when compared to waiting list controls. Comorbid anxiety, depression, high levels of stress and learning problems, did not effect treatment outcome. Improvements in ADHD symptomatology and organizational skills were maintained at a 2‐month follow‐up. Although the programme was successful, close adherence to the programme was necessary for optimum treatment gains. These findings build upon an earlier study that used a more intensive form of programme delivery and support the view that psychosocial interventions can enhance daily functioning for adult ADHD. Copyright © 2003 John Wiley & Sons, Ltd.
Reduction of incongruence in inpatient psychotherapy
Authors: Berking M. , Grosse Holtforth M. , Jacobi C.
Published: April 2003

According to consistency theory, incongruence between individual perceptions and goals reduces well‐being and increases the risk for the development and further maintenance of psychopathological disorders. Successful psychotherapy should therefore reduce the level of incongruence and therapy outcome should be associated with the reduction of incongruence. To test these hypotheses the level of incongruence was assessed in a sample of 62 inpatients undergoing cognitive‐behavioural therapy (CBT) before and after treatment using the Incongruence Questionnaire. Pre–post differences were then correlated with other outcome measures and factor analysis was used to assess the underlying dimensionality of all outcome measures. The level of congruence was reduced substantially by inpatient CBT, changes were positively related to other measures of psychotherapy outcome and incongruence loaded strongly on only one of two emerging factors. Incongruence can be seen as an independent construct. It seems advisable to assess level of incongruence at the beginning of each psychotherapy for effective planning of treatment and at the end of therapy for a comprehensive outcome measurement. The reduction of high levels of incongruence must be seen as an important higher level goal in psychotherapy. Further research has to clarify under what conditions the reduction of incongruence is especially important and what methods are most effective to do so. Copyright © 2003 John Wiley & Sons, Ltd.
Differences in coupling interval‐dependent effects of sotalol on infarcted and noninfarcted areas of dog hearts after myocardial infarction
Authors: Hashimoto Hisakuni , Ohmura Tomohiro , Nakamura Ryuta , Ikeda Yasuhiko , Umemura Kazuo
Published: April 2003

We examined the coupling interval‐dependence of the effects of sotalol (dl‐sotalol) on effective refractory periods (ERPs) and epicardial activation in ventricles of dog hearts after myocardial infarction, and clarified their differences between infarcted and noninfarcted areas. Myocardial infarction was produced by the two‐stage ligation of left anterior descending coronary artery in dogs. At 7 to 9 days after ligation, bipolar electrodes were sutured on the ventricular surface of the noninfarcted and the infarcted areas. Single (S1) or double (S1/S2) electrical stimulations with various coupling intervals were applied on the ventricle during atrial pacing. S1 was triggered by a prior R wave of pacing rhythm with coupling interval of 300 ms (S1[300]) or 180 ms (S1[180]). Coupling intervals of S1 and S2 were between 250 and 130 ms. ERPs, activation delay, and functional refractory periods (FREPs) in ventricles were measured after S1(180) or S1(300). Ventricular activation delay was a time interval from the artifact of S1 or S2 to the most delayed measurable wave. The coupling interval of S1–S2 was 170 or 160 ms. RT intervals were measured in the bipolar ECGs after S1(300) or S1(180). Sotalol was administered intravenously in dosages of 2, 4, and 8 mg/kg. Sotalol prolonged the ERPs in noninfarcted areas in a lesser extent after S1(180) than after S1(300), whereas in infarcted areas the ERP prolongation was in a similar extent after S1(180) and S1(300). Sotalol prolonged the RT intervals in a lesser extent after S1(180) than after S1(300) in noninfarcted areas, but in a similar extent after S1(180) and after S1(300) in infarcted areas. FERPs were also prolonged by sotalol in infarcted areas in a similar extent after S1(180) and after S1(300). Sotalol prolonged ventricular activation delay after S1/S2 in the infarcted areas, which was greater after S1/S2(180/170) than after (300/170). Delayed activation was blocked more frequently after the S1/S2(180/160) than after S1/S2(300/160). These results indicate that the effects of sotalol on ventricular activation delay are reverse‐use dependent in noninfarcted areas but use‐dependent in infarcted areas, which may contribute to suppression of ventricular tachyarrhythmias in patients with coronary heart disease. Drug Dev. Res. 58:258–267, 2003. © 2003 Wiley‐Liss, Inc.
In vivo efficacy of a novel double liposome as an oral dosage form of salmon calcitonin
Authors: Ebato Yoshinori , Kato Yoshinori , Onishi Hiraku , Nagai Tsuneji , Machida Yoshiharu
Published: April 2003

A simple method for the preparation of the inner liposomes for double liposomes (DL) was developed. The encapsulation efficiency of erythrosine in liposomes prepared by this new method is superior to that of the previous method because of the concentration of the drug in the lipid membrane. To evaluate the usefulness of DL prepared by the glass‐filter method modified in this study as an oral dosage form of salmon calcitonin (SCT), a suspension of liposomes containing SCT was administered to rats at a dose of 10 μg SCT/kg. Each type of DL showed better efficacy than its inner liposomes alone. The decrease in plasma calcium level was dependent on the electrical charge and particle size of the inner liposomes. The hypocalcemic efficacy of DL encapsulating SCT‐loading cationic liposomes relative to that after subcutaneous administration of SCT at a dose of 1 μg/kg was 6.47%, which was the largest value obtained. These results indicated that not only the particle size but also the electrical charge of inner liposomes affect intestinal absorption. This study verified that the efficacy was increased because of the decrease in diameter of the inner liposomes and the use of lipid with a positive charge. These findings concluded that DL might be useful as an oral dosage form of SCT. Drug Dev. Res. 58:253–257, 2003. © 2003 Wiley‐Liss, Inc.
Influence of vehicles on the in vitro percutaneous absorption of piroxicam to optimise the formulation of patch tests in dermatology
Authors: d'Arpino Stéphanie , Corbrion‐Archer Valérie , Marty Jean‐Paul , Lantieri Laurent , Vincent Claire‐Marie , Astier Alain , Paul Muriel
Published: April 2003

The present study evaluated the influence of various vehicles on the in vitro percutaneous absorption of piroxicam across human skin under standard diffusion conditions to optimise the formulation of patch tests in dermatology. The transdermal permeation properties of piroxicam were evaluated from five vehicles (PEG 400, propylene glycol, transcutol P, petrolatum, and petrolatum + transcutol P 10%) using Franz diffusion cells. Piroxicam was applied as a saturated solution in vehicles to ensure equal thermodynamic activity of piroxicam in the vehicles. Concentrations of piroxicam were determined by high performance liquid chromatography in epidermis, dermis, and receptor liquid. The release of piroxicam from its vehicles and consequently its cutaneous absorption are influenced by the vehicle assayed and the solubility of piroxicam in each vehicle. The penetration of piroxicam through human skin was clearly enhanced by propylene glycol and petrolatum + transcutol P 10%, with cumulated amounts of piroxicam in the receptor fluid at 48 h of 116±32 and 159±28 μg/mg/cm2 respectively, whereas petrolatum alone did not allow the diffusion of piroxicam. Additional experiments should be conducted in vivo to correlate the results obtained in vitro and to provide clinicians with a more reliable diagnostic test. Drug Dev. Res. 58:283–290, 2003. © 2003 Wiley‐Liss, Inc.
Some comments on the modes of action of nanocomposites in the flame retardancy of polymers
Authors: Lewin Menachem
Published: April 2003

Nanocomposites of polymers with montmorillonite (MMT) yield upon pyrolysis and combustion an MMT‐rich surface of the char. The prevalent approach considers this accumulation as due to the gasification of the polymer and subsequent gradual precipitation of the MMT on the surface. According to the present paper, the enrichment in MMT is postulated to be due to a migration or convection of the MMT to the surface driven mainly by the lower surface free energy of the MMT. The role of the surface free energy in the surface structure of polymer blends, especially those involving a silicon‐containing component, is discussed. The enrichment occurs above the glass transition temperature and is temperature dependent. XPS evidence for the accumulation of MMT on the surface of a polystyrene/MMT nanocomposite is reviewed. Its dependence on the stability of the nanocomposite structure, and particularly on the stability of the quaternary ammonium compounds that bind the polymer to the MMT, is pointed out. The importance of the surface free energy in the flame retardancy of polymer blends as well as polymer‐additive mixtures is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
A flux‐splitting solver for shallow water equations with source terms
Authors: Rebollo Tomás Chacón , Nieto Enrique D. Fernández , Mármol Macarena Gómez
Published: April 2003

This paper introduces a stable flux‐splitting solver for one‐dimensional (1D) shallow water equations. This solver is specifically designed to satisfy a strengthened consistency condition for stationary solutions that ensures the stability and accuracy of the scheme. It applies to channels with variable depth and width, including terms modelling friction at bottom and vertical walls. Some numerical tests by comparison to both analytical solutions and experimental measurements show the good performances of the scheme. Copyright © 2003 John Wiley & Sons, Ltd.
A novel fully implicit finite volume method applied to the lid‐driven cavity problem—Part I: High Reynolds number flow calculations
Authors: Sahin Mehmet , Owens Robert G.
Published: April 2003

A novel implicit cell‐vertex finite volume method is described for the solution of the Navier–Stokes equations at high Reynolds numbers. The key idea is the elimination of the pressure term from the momentum equation by multiplying the momentum equation with the unit normal vector to a control volume boundary and integrating thereafter around this boundary. The resulting equations are expressed solely in terms of the velocity components. Thus any difficulties with pressure or vorticity boundary conditions are circumvented and the number of primary variables that need to be determined equals the number of space dimensions. The method is applied to both the steady and unsteady two‐dimensional lid‐driven cavity problem at Reynolds numbers up to 10000. Results are compared with those in the literature and show excellent agreement. Copyright © 2003 John Wiley & Sons, Ltd.
Calculation of turbulent fluid flow and heat transfer in ducts by a full Reynolds stress model
Authors: Rokni Masoud , Sundén Bengt
Published: April 2003

A computational method has been developed to predict the turbulent Reynolds stresses and turbulent heat fluxes in ducts by different turbulence models. The turbulent Reynolds stresses and other turbulent flow quantities are predicted with a full Reynolds stress model (RSM). The turbulent heat fluxes are modelled by a SED concept, the GGDH and the WET methods. Two wall functions are used, one for the velocity field and one for the temperature field. All the models are implemented for an arbitrary three‐dimensional channel.

Fully developed condition is achieved by imposing cyclic boundary conditions in the main flow direction. The numerical approach is based on the finite volume technique with a non‐staggered grid arrangement. The pressure–velocity coupling is handled by using the SIMPLEC‐algorithm. The convective terms are treated by the van Leer scheme while the diffusive terms are handled by the central‐difference scheme. The hybrid scheme is used for solving the ε equation.

The secondary flow generation using the RSM model is compared with a non‐linear k–ε model (non‐linear eddy viscosity model). The overall comparison between the models is presented in terms of the friction factor and Nusselt number. Copyright © 2003 John Wiley & Sons, Ltd.
Computational study of unsteady turbulent flows around oscillating and ramping aerofoils
Authors: Barakos G. N. , Drikakis D.
Published: April 2003

The aim of this work is to computationally investigate subsonic and transonic turbulent flows around oscillating and ramping aerofoils under dynamic‐stall conditions. The investigation is based on a high‐resolution Godunov‐type method and several turbulence closures. The Navier–Stokes and turbulence transport equations are solved in a strongly coupled fashion via an implicit‐unfactored scheme. We present results from several computations of flows around oscillating and ramping aerofoils at various conditions in order to (i) assess the accuracy of different turbulence models and (ii) contribute towards a better understanding of dynamic‐stall flows. The results show that the employed non‐linear eddy‐viscosity model generally improves the accuracy of the computations compared to linear models, but at low incidence angles the Spalart–Allmaras one‐equation model was found to provide adequate results. Further, the computations reveal strong similarities between laminar and high‐Reynolds number dynamic‐stall flows as well as between ramping and oscillating aerofoil cases. Investigation of the Mach number effects on dynamic‐stall reveals a delay of the stall angle within a range of Mach numbers. Investigation of the reduced frequency effects suggests the existence of an (almost) linear variation between pitch rate and stall angle, with higher slope at lower pitch rates. The pitch rate affects both the onset of dynamic‐stall as well as the evolution of the associated vortical structures. Copyright © 2003 John Wiley & Sons, Ltd.
An efficient method for capturing free boundaries in multi‐fluid simulations
Authors: Xiao F. , Ikebata A.
Published: April 2003

An easy‐to‐use front capturing method is devised by directly solving the transport equation for a volume of fluid (VOF) function. The key to this method is a semi‐Lagrangian conservative scheme, namely CIP_CSL3, recently proposed by the author. In the CIP_CSL3 scheme, the first‐order derivative of the interpolation polynomial at each cell centre is used to control the shape of the reconstructed profile. We show in the present paper that the first‐order derivative, which plays a crucial role in reconstructing the interpolation profile, can also be used to eliminate numerical diffusion. The resulting algorithm can be directly used to compute the VOF‐like function and retain the compact thickness of the moving interface in multi‐fluid simulations. No surface reconstruction based on the value of VOF function is required in the method, which makes it quite economical and easy to use. The presented method has been tested with various interfacial flows including pure rotation, vortex shearing, multi‐vortex deformation and the moving boundaries in real fluid as well. The method gives promising results to all computed problems. Copyright © 2003 John Wiley & Sons, Ltd.
Changes in the surface water hydrologic characteristics of an endoreic basin of northern Mexico from 1970 to 1998
Authors: Viramontes D. , Descroix L.
Published: April 2003

The western Sierra Madre is the main water‐providing area of northern Mexico. However, most of this mountain range has suffered a progressive degradation of soils and vegetation due to overgrazing and deforestation, for four or five decades. The objective of this study is to determine the impacts of these changes on water balance and hydrodynamic basin behaviour.

The hydrological data of two basins (the Sextin basin, 4660 km2 and the Ramos basin, 7130 km2) of this area were analysed. Annual runoff coefficients have not changed. Therefore, other indices were used to determine changes in the streamflow regime:

an index of irregularity of daily discharge;

the separation of flood flow and base flow;

the lag time of the watersheds;

the baseflow recession index;

the two‐day recession index.

Some changes were noticeable at the basin scale in the water balance of the catchments:

the ratio of the flood runoff coefficient to the base runoff coefficient increased from the 1970s to the 1990s;

the basin lag time decreased 2·1% in the Ramos basin and 6·1% in the Sextin basin;

the two‐day recession index and the baseflow recession index increased, reflecting a more rapid decrease of streamflow after the peak flow;

the mean annual runoff coefficient and the irregularity as estimated by the index used here showed no significant evolution.

The convergence of such observations confirms that dramatic changes in the evolution of water resources in the near future in this area are to be expected, if the current land use is not strongly modified. Water management and dam operation would also be seriously affected. Copyright © 2003 John Wiley & Sons, Ltd.
Exportation of organic carbon from the Amazon River and its main tributaries
Authors: Moreira‐Turcq Patricia , Seyler Patrick , Guyot Jean Loup , Etcheber Henri
Published: April 2003

As part of a joint Brazilian–French project, entitled ‘Hydrology and Geochemistry of the Amazon Basin’, we carried out a seven‐year study (1994–2000) on the distribution, behaviour and flux of particulate and dissolved organic carbon in the Amazon River and its main tributaries (the Negro, Solimões, Branco, Madeira, Tapajós, Xingú and Trombetas rivers).

The concentrations of particulate and dissolved organic carbon varied from one river to another and according to the season, but dissolved organic carbon (DOC) always accounted for about 70% of the total organic carbon (TOC). The mean concentration of dissolved organic carbon was 6·1 mg l−1in the Madeira River, 5·83 mg l−1in the Solimões River and 12·7 mg l−1in the Negro River. The percentage in weight of the particulate organic carbon decreased as the concentration of suspended matter increased. The Solimões River contributed the most carbon to the Amazon River: about 500 kg C s−1during the high water period and about 300 kg C s−1during the low water period. However, the temporal variations in organic carbon in the Amazon River (i.e. downstream of Manaus) are basically controlled by inputs from the Negro River and its variations. The Negro River does not produce a simple dilution effect. During the high water period (between March and August) the TOC flux, calculated as the sum of the Solimões, Negro and Madeira tributaries, was about 5·7 × 1013g C yr−1, whereas during the low water period (between September and February) the TOC flux was about 2·6 × 1013g C yr−1.

The mean annual flux of TOC at Óbidos (the final gauging station upstream of the estuary) was about 3·27 × 1013g C yr−1(i.e. 32·7 ± 3·3 Tg yr−1). Of this, the flux of DOC represents about 2·7 × 1013g C yr−1and the flux of particulate organic carbon (POC) represents about 0·5 × 1013g C yr−1. The mean annual input of TOC by all tributaries (Negro, Solimões, Madeira, Trombetas, Tapajós and Xingú) was about 2·8 × 1013g C yr−1. When we compared this input with the output recorded at Óbidos (3·27 × 1013g C yr−1), we found that the amount of organic carbon increased (about 0·4 × 1013g C yr−1). This shows that other important sources of organic carbon exist in the lower reaches of the Amazon River. These inputs can be attributed to the adjacent floodplain lake system, called ‘várzea’. Copyright © 2003 John Wiley & Sons, Ltd.
Carbon and metal concentrations, size distributions and fluxes in major rivers of the Amazon basin
Authors: Benedetti Marc F. , Mounier Stephane , Filizola Naziano , Benaim Jean , Seyler Patrick
Published: April 2003

The chemical composition of the Amazon River results from the mixing of two water types: black water and white water. On‐site fractionation by sequential tangential ultrafiltration (STUF) was used to differentiate transported organic carbon and to determine the distribution and association of major and trace elements with different size fraction of the organic carbon (OC). Several sampling campaigns (1994–1996) allow a monthly quantification of particulate (OCP, MeP), colloidal (OCC, MeC) and dissolved (OCD, MeD) organic carbon and metal ions inputs. In white rivers the OC is mainly concentrated in the low molecular weight fraction (OCD < 5000 D) while in black rivers most of the OC is in the heavier molecular weight fractions (OCP and OCC > 5 kDa). For Mg, Ca and K, 50% of the total amount of each element is found in fraction MeD while 15% and 35% are found in fractions MeC and MeP, respectively. Al and Fe are in the particulate fraction at 99% of the total metal concentration for all river samples. This work emphasizes the coagulation processes and the sink for elements in the mixing zone. These physicochemical transformations of the organic matter vary seasonally. The changes happen during the transition periods: before high‐level waters and before low‐level waters. By way of flux measurement, a seasonal carbon loss was observed. The estimated annual organic carbon flux of the Amazon at Òbidos is 28 × 106 t. At the same time, an average of 9 × 106 t of organic carbon per year is retained in the reach between Manaus and Òbidos, probably via coagulation processes. Copyright © 2003 John Wiley & Sons, Ltd.
The socioeconomic roots of conflict in the Caucasus
Authors: Glinkina Svetlana P. , Rosenberg Dorothy J.
Published: April 2003

We argue that the conflicts in the Caucasus are the result of the abrogation by the elite of the earlier, Soviet era social contract. This process was accompanied by the collapse of the formal economy; evidenced by huge national income compression, falling public goods provision, and growing inequality and poverty. In the absence of state provision of basic amenities and governance, ordinary people are compelled to fall back on kinship ties. Declining standards of governance facilitate state‐sponsored corruption and criminality in a setting where the shadow economic activity is increasingly important to individual survival strategies. Oil pipelines and the right to control the transit of goods both legal and illegal also underlie conflict in the region. Criminality has replaced ethnicity as the major motivation for conflict and conflict per se has become a lucrative source of income. Copyright © 2003 John Wiley & Sons, Ltd.
The political economy of Malaysian federalism: economic development, public policy and conflict containment
Authors: K. S. Jomo , Hui Wee Chong
Published: April 2003

Conflicts within the Malaysian federation have been rooted in socio‐economic disparities and the struggle for control of natural resource rents, which state governments previously had exclusive control over, as originally provided for by the federal constitution. The advance of fiscal centralization since then has also aggravated federal–state tensions, which have been relatively ignored due to the long‐standing Malaysian pre‐occupation with inter‐ethnic tensions. Inter‐regional resource transfers and central fiscal and political dominance have been used to undermine the more independent state governments, especially those held by opposition parties. While the federal government is clearly dominant, central control over the state governments has varied, especially in Sabah and Sarawak, with the continued hegemony of the national ruling coalition depending on successfully combining the carrot with the stick. Copyright © 2003 John Wiley & Sons, Ltd.
Economic aspects of the Palestinian—Israeli conflict: the collapse of the Oslo Accord
Authors: Naqib Fadle M.
Published: April 2003

Since October 2000 Israel and the Palestinians of the West Bank and Gaza Strip have become entangled in a bloody confrontation. This paper focuses on the economic relationship between the Israeli economy and the Palestinian economy of the West Bank and Gaza Strip, and the ways in which this has contributed to the collapse of the Oslo Accord. The paper finds that Israeli policies have distorted and weakened the Palestinian economy, particularly in the areas of trade (dependence upon one major trade partner), taxation (loss of revenues to finance development spending) as well as in the labour market (controls on labour flows) and in Palestinian access to land (including land confiscation). As a result, besides income compression, poverty and unemployment have risen in the Palestinian territories. Two central issues of the conflict need to be addressed: the Palestinian right to sovereignty over their land and their right to free their economy from colonial dependency on Israel. Copyright © 2003 John Wiley & Sons, Ltd.
Knowledge management in the professional organization: a model with application to CMG software testing
Authors: Kerkhof Cesanne , Ende Jan van den , Bogenrieder Irma
Published: April 2003

Knowledge and the management of knowledge are recognized as becoming more important to modern organizations. Unfortunately, modern literature is not clear on the ways to implement knowledge management in practice. This article presents a model for this purpose, dedicated to professional organizations. Present theories about knowledge, learning organizations and knowledge transfer form the basis of the model. The model is applied to CMG Software Testing. Copyright © 2003 John Wiley & Sons, Ltd.
The facilitating factors for organizational learning: bringing ideas from complex adaptive systems
Authors: Chiva‐Gómez Ricardo
Published: April 2003

The importance of the factors that facilitate organizational learning have traditionally been outlined in the literature. However, there is no agreement about what the essential facilitating factors are, as each author emphasizes different features. Complexity science is increasingly being used by researchers and practitioners to improve their understanding of organizations. This exploratory study tries to determine the essential facilitating factors for organizational learning, and demonstrate the importance of the ideas from complex adaptive systems (CAS) to it. In order to do this, we put forward a comparative case study of four heterogeneous companies from the Spanish ceramic tile sector in which we analyzed the facilitating factors for organizational learning, by relating them with ideas from CAS. As a result, we determined that the five attributes suggested by CAS to facilitate organizational learning were present in the innovative companies, which had the most organizational learning facilitating factors, and three of them were only present in the company with the highest performance and the most innovative approach: individuals' relationship with the environment; cultural diversity; and state of equilibrium between formal and informal structures. Copyright © 2003 John Wiley & Sons, Ltd.
Cholinergic nicotinic receptors: Competitive ligands, allosteric modulators, and their potential applications
Authors: Romanelli M. Novella , Gualtieri Fulvio
Published: April 2003

Discovery of the important role played by nicotinic acetylcholine receptors (nAChRs) in several CNS disorders has called attention to these membrane proteins and to ligands able to modulate their functions. The existence of different subtypes at multiple levels has complicated the understanding of this receptor's physiological role, but at the same time has increased the efforts to discover selective compounds in order to improve the pharmacological characterization of this kind of receptor and to make the possible therapeutical use of its modulators safer. This review focuses on the structure of new ligands for nAChRs, agonists, antagonists and allosteric modulators, and on their possible applications. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 4, 393–426, 2003
Novel antiplasmodial agents
Authors: Go Mei‐Lin
Published: April 2003

The morbidity and mortality associated with malaria have spurred efforts to find novel antimalarial agents with improved potency and selectivity. Leads for agents continue to be obtained from natural sources (plants and microorganisms) and chemical syntheses. Screening of commercial or specialized databases have also yielded promising leads. The structural diversity of compounds with good (micromolar and lower) activity point to the considerable tolerance for different structural elements in the “antimalarial pharmacophore.” It may also be a reflection of the varied targets present in the plasmodia. The challenge in malaria chemotherapy is to find safe and selective agents whose potencies will not be compromised by plasmodial resistance. Modification of potential leads should also aim at improving “drug‐like” character, viz. to ensure acceptable oral bioavailability. A review of the literature shows that there is a growing trend towards the development of target‐specific antimalarial agents (for example, agents inhibiting plasmodial farnesyl transferase, cyclin dependent kinases, proteases, choline transport). An increasing number of reports focus on the development of chemosensitizers, agents that are capable of reversing plasmodial resistance. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 4, 456–487, 2003
On the fractionation of linear polyethylene
Authors: Salovey R. , Hellman M. Y.
Published: April 2003

Fibrillar crystals of polyethylene are prepared by stirring solutions of the polymer in xylene at elevated temperatures. Extraction of these crystals with xylene at controlled temperatures is a convenient method of preparing narrow fractions of linear polyethylene of molecular weights below 105. Higher molecular weight fractions were readily obtained by column fractionation but not by the extraction of fibrillar crystals.
Determination of rubber dynamic properties using a sinusoidal vibrator and weighted specimen
Authors: Frazee J. D. , Tucker J.
Published: April 2003

A test procedure is described for determining the dynamic response of highly loaded elastomers. This consists of weighted column vibration specimen monitored with accelerometers. Results on three natural rubber and three SBR standard formulations are briefly summarized. The effect of temperature and solids loading on the transmissibility and resonant frequency is discussed. Certain features of the tests and the availability of both simplified and complex (general) analyses recommend it for obtaining a broader knowledge of the dynamic mechanical properties of loaded vulcanizates.
A light‐scattering photometer for the angular range 6–170°
Authors: Meyerhoff G. , Moritz U. , Darskus R. L.
Published: April 2003

A light‐scattering phtometer for measurements on solutions in the angular range 6–170° is described. Its use is illustrated by the determination of the average molecular weights Mw and Mn, as well as the gyration radii 〈r2〉z1/2 and 〈r2〉n1/2, on a polystryene fraction.
Polymerization of 3‐vinylpyrene with Ziegler‐Natta catalyst
Authors: Tanikawa Kiyoshi , Kusabayashi Shigekazu , Hirata Hirotaka , Mikawa Hiroshi
Published: April 2003

Using a Ziegler‐Natta catalyst, we obtained a polymer of 3‐vinylpyrene having large π‐electron systems as pendant groups. The conversion was highest at AlEt3/TiCl4 = 1/1, being ca. 90%. It was lower with TiCl4 alone, and was also reduced down to ca. 30% at Al/Ti = 7/1. The conversion exceeded 80% after only 7 hr. at Al/Ti = 2/1. This polymer has a melting point of 214°C. determined by a polarizing hot‐stage microscope examination. X‐ray examination showed that this polymer is crystalline, although rather poor. The polymer is soluble in many solvents. From the similarity of ultraviolet absorption spectra of 3‐ethylpyrene and polyvinylpyrene prepared by benzoyl peroxide (BPO), TiCl4, AlEt3–TiCl4, this polymer is believed to have a linearly combined chain structure with a large pendant pyrene nucleus and to have no crosslinking at all.
A novel copolymerization reaction
Authors: Meyers R. A. , Wilson E. R.
Published: April 2003

A new addition polymerization reaction is described which involves the copolymerization of sulfur dichloride or sulfur monochloride with a diolefin. Sulfur dichloride copolymerizes with bis(1,2,3,6‐tetrahydrophthalimide) (A) to form poly[N,N′‐m‐phenylenebis(3,4‐dicarboxy‐6‐chlorocyclohexyl) sulfide imide] (I). Sulfur monochloride copolymerizes with A to form poly[N,N′‐m‐phenylenebis(3,4‐dicarboxy‐6‐chlorocyclohexyl) disulfide imide] (II). The polyimides, I and II were characterized by elemental analysis, infrared spectroscopy, and inherent viscosity. The mechanism of polymerization is discussed.
Estimation of the ceiling temperature for the polymerization of acetone
Authors: Waywell David R.
Published: April 2003

The thermodynamics of the polymerization of acetone through the carbonyl group has been investigated in an attempt to find the limiting experimental conditions for producing high molecular weight polymer. Approximate values for the entropy and enthalpy of polymerization were estimated empirically from data published on polyolefins and polyacetals. A low negative heat of polymerization (ΔHp = −2.4 kcal mole.−t) rather than a high negative entropy (Δ Sp = −45 cal mole−1 (deg K)−1) was considered to be the controlling influence in the polymerization. From these values, a ceiling temperature of –220°C was calculated for the reaction of gaseous acetone to form amorphous polyacetone.
The cationic polymerization of “endo” ‐dicyclopentadiene, 1,2–dihydro‐“endo” ‐dicyclopentadiene and 9,10–dihydro‐“endo” ‐dicyclopentadiene
Authors: Cesca Sebastiano , Priola Aldo , Santi Giuliano
Published: April 2003

The polymerizations of “endo” ‐dicyclopentadience (I), 1,2–dihydro‐“endo”‐dicyclopentadiene (II) and 9,10–dihydro‐“endo”‐dicyclopentadiene (III), initiated by cationic systems, have been investigated under different conditions. Linear polymers with M̄n in the range 1300–4500 have been obtained with (I) and (II): poly‐(I) shows less than one double bond for structural unit. In the case of (III) only oligomers were observed. Copolymerization runs show a reactivity of (III) lower than (II). Spectroscopic and chemical analyses of the polymers obtained indicate that besides the norbornene double bond, also the cyclopentenic unsaturation, present in (I) and (III), reacts.

Some evidences for a hydride shift in cyclopentence ring, after the attack of the initiator, were collected. In the case of poly‐(I) the main enchainment resulted from the norbornene double bond opening, but about 30% of nortricyclene repeating unit was also observed.
Thermal characterization of polyester–melamine coating matrices prepared under nonisothermal conditions
Authors: Gamage N. J. W. , Hill D. J. T. , Lukey C. A. , Pomery P. J.
Published: April 2003

Thermal analysis methods (differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis) were used to characterize the nature of polyester–melamine coating matrices prepared under nonisothermal, high‐temperature, rapid‐cure conditions. The results were interpreted in terms of the formation of two interpenetrating networks with different glass‐transition temperatures (a cocondensed polyester–melamine network and a self‐condensed melamine–melamine network), a phenomenon not generally seen in chemically similar, isothermally cured matrices. The self‐condensed network manifested at high melamine levels, but the relative concentrations of the two networks were critically dependent on the cure conditions. The optimal cure (defined in terms of the attainment of a peak metal temperature) was achieved at different oven temperatures and different oven dwell times, and so the actual energy absorbed varied over a wide range. Careful control of the energy absorption, by the selection of appropriate cure conditions, controlled the relative concentrations of the two networks and, therefore, the flexibility and hardness of the resultant coatings. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1603–1621, 2003
Copolymerization of α‐terpineol with styrene: Synthesis and characterization
Authors: Yadav Sarika , Srivastava A. K.
Published: April 2003

Radical copolymerization of α‐terpineol with styrene (Sty) initiated by azobisisobutyronitrile in xylene at 80 ± 0.1 °C for 2 h followed ideal kinetics and resulted in the formation of a functional and alternating copolymer as evidenced by spectral analysis. The activation energy was 28 kJ/mol. α‐Terpineol underwent copolymerization as well as a chain‐transfer reaction. The values of the monomer reactivity ratios calculated by the Kelen–Tüdos method were r1 (Sty) = 0.033 and r2 (α‐terpineol) = 0.004. The Alfrey–Price Q‐e parameters for α‐terpineol were calculated as 0.104 and 3.052, respectively. The mechanism of copolymerization is elucidated, and it is concluded that the double bond present in the monocyclic ring of α‐terpineol is an active site for copolymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1700–1707, 2003
Photocurable and thermally stable polymers based on 1,4‐pentadien‐3‐one‐1‐p‐hydroxyphenyl‐5‐p‐phenyl methacrylate: Copolymerization with ethyl acrylate
Authors: Arun A. , Reddy B. S. R.
Published: April 2003

1,4‐Pentadien‐3‐one‐1,5‐bis(p‐hydroxyphenyl) (PBHP) was prepared by reacting p‐hydroxybenzaldehyde and acetone in the presence of an acid catalyst. 1,4‐Pentadiene‐3‐one‐1‐p‐hydroxyphenyl‐5‐p‐phenyl methacrylate (PHPPMA) monomer was prepared by reacting PBHP dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in the presence of triethylamine. A free‐radical solution polymerization technique was used for synthesizing homo‐ and copolymers of different feed compositions of PHPPMA and ethyl acrylate (EA) in EMK as a solvent with benzoyl peroxide as a free‐radical initiator at 70 ± 1 °C. All the polymers were characterized with IR and 1H NMR techniques. The compositions of the copolymers were determined with the 1H NMR technique. The copolymer reactivity ratios were evolved with Kelen–Tudos (EA = 1.25 and PHPPMA = 0.09) and extended Kelen–Tudos (EA = 1.30 and PHPPMA = 0.09) methods. Q (0.48) and e (1.68) values for the new monomer (PHPPMA) were calculated with the Alfrey–Price method. UV absorption spectra for poly(PHPPMA) showed two absorption bands at 302 and 315 nm. The photocrosslinking properties of the polymer samples were examined with the solvent method. Thermal analyses of the polymers were performed with the thermogravimetric‐differential thermogravimetric technique. First, the decomposition temperatures started for poly(PHPPMA), copoly(EA‐PHPPMA) (62:38), and copoly(EA‐PHPPMA) (41:59) were at 350, 410, and 417 °C, respectively. A gel permeation chromatographic method was used for determining the polymer molecular weights (weight‐average molecular weight: 2.67 × 104 and number‐average molecular weight: 1.41 × 104) and polydispersity index (1.89). The solubility of the monomer and the copolymers occurred at 30 °C with solvents having different polarities. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1632–1640, 2003