bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and simulation of propylene polymerization in nonideal loop reactors
Authors: Reginato A. S. , Zacca J. J. , Secchi A. R.
Published: April 2004

A dynamic mathematical model for liquid‐phase polymerization in loop reactors was developed and implemented in language C using S‐functions in a MATLAB/SIMULINK environment. It is based on a nonideal continuous stirred‐tank reactor (CSTR) model capable of dealing with multisite copolymerization of olefins. The kinetic scheme includes a specific mechanism for hydrogen effect on rate of polymerization observed on both laboratory experiments and industrial plant trials. A nonideality due to polymer segregation at the reactor output was inserted into the model to better predict reactor slurry density. Polymer moment balances were used to compute resin properties, such as average molecular weights, polydispersity, and melt flow index. Dynamic data from an industrial polypropylene plant were used for parameter estimation and model validation.
Numerical simulation of solids suspension in a stirred tank
Authors: Derksen J. J.
Published: April 2004

Large‐eddy simulations of the turbulent flow driven by a Rushton turbine have been coupled to a Lagrangian description of spherical, solid particles immersed in the flow. The working fluid was water, whereas the solid particles had the properties of glass beads. Simulations were restricted to a lab‐scale tank (volume 10−2 m3), and relatively low solids volume fractions (up to 3.6%). Two sets of particles were considered with particle dia. of 0.30 mm and 0.47 mm, respectively. It has been investigated to what level of detail the particle motion needs to be modeled in order to meet Zwietering's just suspended criterion. It appeared to be essential to take particle‐particle collisions into account, mainly because of their exclusion effect that prevents unrealistic buildup of particle concentrations closely above the bottom. The simulations give detailed insight in the behavior of the particles, and in the way that the liquid flow is altered by the presence of the particles. The frequency and intensity of particle‐particle collisions, and particle‐impeller collisions, have been investigated. Furthermore, it will be demonstrated that the rotational Reynolds numbers of the big (0.47 mm) particles were of the same order of magnitude as their translational counterparts.
Unified model for NOX absorption in aqueous alkaline and dilute acidic solutions
Authors: Patwardhan Janaki A. , Joshi Jyeshtharaj B.
Published: April 2004

The absorption of NOX gases in water and alkalies [NaOH, NH4OH, Ca(OH)2] provides commercially important products nitric acid and salts (nitrates and nitrites), respectively. This complex phenomena of mass transfer with chemical reactions is described quantitatively in terms of [H√(kD)]J values for J = N2O3, N2O4. However, the reported value of H√(kD) for N2O3 absorption in strong alkaline solution was 50 times its value in water. For the intermediate case of NOX absorption in weak alkali Ca(OH)2, it was necessary to have a mathematical model which incorporated the HNO2 decomposition, as well as neutralization by alkali. This led to a unified model for NOX absorption, which can be used for predicting point rates of NOX absorption as well as selectivity, for various gas compositions and liquid‐phase pH. Parametric sensitivity has been reported. A comparison of the model predictions with data from patent on Ca(NO2)2 manufacture has been made to test the model validity.
Chaotic advection in a three‐dimensional stokes flow
Authors: Rodrigo A. J. S. , Mota J. P. B. , Lefevre A. , Leprévost J. C. , Saatdjian E.
Published: April 2004

Mixing by chaotic advection is studied in a new 3‐D flow geometry. It consists of two confocal elliptic cylinders whose inner and outer boundaries glide circumferentially so that the geometry does not vary with time. Dye advection experiments have been performed and compared to numerical streak lines calculated using the analytical solution of Stokes' equations in elliptical cylindrical coordinates. Experiments show that particle trajectories remain for all practical purposes inside tubes defined by the potential mixing zone during the whole process. For the case where the elliptic cylinders turn time periodically in opposite directions, we examine the effect of the modulation frequency of the boundary displacement protocol by defining appropriate dimensionless control parameters and then numerically monitoring the advection of a passive scalar. It is shown that for a given average axial velocity, there is an optimum modulation frequency that maximizes the mixing enhancement due to chaotic advection.
Flow‐induced particulate separations
Authors: Roberts Brian W. , Olbricht W. L.
Published: April 2004

Separating particles from the liquid in which they are suspended is often an important step in processing multiphase materials such as suspensions and emulsions. We describe a new method to separate neutrally buoyant particles from viscous liquids. The method is based on the low Reynolds number motion of freely‐suspended particles at bifurcations—points where a tube or channel splits into multiple tubes. We show experimentally that the partitioning of particles at a bifurcation differs from the partitioning of the suspending fluid. The effects of particle size, particle volume fraction, and shape of the bifurcation on particle partitioning are examined. Furthermore, we demonstrate that when tubes and bifurcations are arranged in certain ways, the particles can take preferential paths through the network and can be separated from the liquid in which they are suspended. The data show that the particle separation can be enhanced in relatively simple networks consisting of just a few interconnected channels.
Target linearization and model predictive control of polymerization processes
Authors: Bindlish Rahul , Rawlings James B.
Published: April 2004

Modeling and control of prototypical industrial polymerization processes are presented in the presence of disturbances and plant‐model mismatch. The process model consists of the material balances for the reactor, energy balance for the reactor, and a simplified dynamic model for the downstream flash separator. The process model is used to develop a TLMPC that separates the target calculation from dynamic regulation in a closed‐loop setting. The main feature of the proposed controller (TLMPC) is that the targets are calculated from the nonlinear model, and then used to get the correct linearized model. The linearized model is utilized to calculate the actual control moves for dynamic regulation, and develop an extended Kalman filter for state estimation. The resulting TLMPC controller does not have the computational burdens associated with a full NMPC and gives similar performance to NMPC. The TLMPC shows optimal plant startup, product grade transitions, and regulation around a set point for the polymerization process in comparison to a fixed LMPC. Robustness with respect to incorrect model kinetic parameters, initial state estimates and measured disturbances is also shown for TLMPC, as compared to LMPC.
Novel solar reactor for studying ultrafast gas–solid reactions above 2,000 K
Authors: Steiner E. , Ganz J. , Meier A. , Sturzenegger M.
Published: April 2004

A novel solar chemical reactor has been designed and tested for kinetic experiments with μm‐sized metal oxide particles. The solar reactor is essentially a tubular reactor with a continuous feed of particles suspended in a carrier gas. The suspension is electrically preheated in the back part of the solar reactor. Chemical conversion occurs in the high‐temperature zone in the front part of the solar reactor where concentrated solar radiation enters the reactor through a quartz window. Under typical operating conditions, the particle residence time in the high‐temperature zone was estimated to be 50 ms. Reduction of manganese iron oxides showed that flux‐density distributions of 450 to 770 W·cm−2 produced maximum particle temperatures of 2,200 K. Chemical reactivity studies also revealed that quenching is insufficient for very reactive materials. Therefore, an alternative quench device has been tested at room temperature and is discussed here.
New solid equation of state combining excess energy mixing rule for solid–liquid equilibria
Authors: Twu Chorng H. , Tassone Vince , Sim Wayne D.
Published: April 2004

Crude oil is a mixture of light and heavy hydrocarbon components. The light components in crude oil keep the heavy components soluble in solution. However, the cooling of crude oil below its solidification point leads to the formation of a solid‐wax phase. A number of thermodynamically based models have been proposed in the literature for the prediction of wax formation in both crude oils and fuels. Some of these models assume ideal liquid solution behavior. Others are a modification of the regular solution theory or the Flory‐Huggins model for activity coefficients, with varying degrees of success. The absence of a proper model in the petroleum industry to describe the liquid‐phase nonideality for mixtures of hydrocarbons with large differences in size is still one of the major problems in solid–liquid equilibrium calculations. A simple methodology is proposed to develop a cubic equation of state (CEOS) for the solid phase to allow the accurate calculation of solid–liquid equilibria. The methodology is successfully applied to the Twu‐Sim‐Tassone (TST) cubic equation of state. The solid TST equation of state is then combined with the TST excess Helmholtz energy mixing rule to handle highly nonideal systems for the accurate prediction of solid–liquid phase equilibria.
Advances in biomaterials, drug delivery, and bionanotechnology
Authors: Langer Robert , Peppas Nicholas A.
Published: April 2004

Biomaterials are widely used in numerous medical applications. Chemical engineering has played a central role in this research and development. Polymers as biomaterials, materials and approaches used in drug and protein delivery systems, materials used as scaffolds in tissue engineering, and nanotechnology and microfabrication techniques applied to biomaterials are reviewed.
Heterogeneous batch‐extractive distillation of minimum boiling azeotropic mixtures
Authors: Donis Ivonne Rodríguez , Esquijarosa Jhoany Acosta , Gerbaud Vincent , Joulia Xavier
Published: April 2004

Following previous studies on heterogeneous batch azeotropic distillation, the use of heterogeneous entrainers for the separation of binary azeotropic mixtures by extractive distillation is evaluated. This process is well suited for systems where the entrainer forms a saddle heteregeneous azeotrope with any one of the original components, such systems being unsuitable for nonextractive heterogeneous batch‐distillation processes. Process feasibility is assessed from the isovolatility curves and the volatility order diagram. It tells us whether the homogeneous original component or the heteroazeotrope is drawn at the column top and establishes the distillation tasks sequence using a batch‐rectifying column. The theoretical insights are validated via rigourous simulation for the separation of the acetonitrile–water mixture with hexylamine or butyl acetate. Finally, the same method is applied for the theoretical analysis of a reported industrial example where water is used for the separation of a binary organic mixture, leading to a complex ternary system with several binary azeotropic points and a homogenous ternary azeotrope.
Feasible products in batch reactive distillation
Authors: Guo Zhe , Ghufran Mudassir , Lee Jae W.
Published: April 2004

A systematic feasibility evaluation for batch reactive distillation systems is addressed. In each batch configuration, feasibility criteria are obtained for ternary reactive systems by using residual curve maps (RCMs) and reaction equilibrium manifolds. If one of the reaction products is an unstable node (UN) and is reachable from all distillation regions, a rectifier can be used for producing pure products. Even if this unstable node is only reachable from one specific distillation region, a rectifier can still be used when a part of the reaction equilibrium curve lies within the same distillation region as the product. Symmetric results are conserved for a batch stripper with one stable node (SN) product. Finally, pure products are produced in middle‐vessel columns when the UN and SN products share the same distillation region with a part of the reaction equilibrium curve. Although these criteria are obtained for ternary systems, they can be extended to multicomponent reactive systems.
Dynamics of flow and diffusion of adsorbing gases in Al2O3 and Pd‐Al2O3 pellets
Authors: Dogan Meltem , Dogu Gülsen
Published: April 2004

A nonisobaric pulse‐response technique was proposed for the simultaneous analysis of flow and diffusion of adsorbing tracers in porous solids. Relative contributions of viscous flow, Knudsen flow, surface flow, and effective diffusion of adsorbing (hydrogen and carbon dioxide) and inert (helium) tracers in alumina and Pd‐alumina pellets were evaluated. Hydrogen permeability was shown to increase by Pd impregnation into alumina, due to the contribution of surface flow, especially at low temperatures. The tortuosity factor, corresponding to the viscous and Knudsen flow, was found to be less than the tortuosity factors evaluated from effective diffusivities obtained from isobaric pulse‐response experiments.
Characterization of anion‐exchange membranes containing pyridinium groups
Authors: Kang Moon‐Sung , Choi Yong‐Jin , Moon Seung‐Hyeon
Published: April 2004

A poly(vinyl chloride) (PVC)/glycidyl methacrylate (GMA)‐divinyl benzene (DVB)‐based membrane was prepared via monomer sorption, and then pyridium or its derivates (that is, 4‐ethyl pyridium, 4‐tetrabutyl pyridium) were introduced into the PVC/poly(GMA‐DVB) base membrane. The effects of pyridinium anion‐exchangeable sites on the water splitting and the electrochemical properties of the membrane were investigated. The electrochemical properties and the water splitting on the anion‐exchange membranes were compared with selected commercial membranes containing quaternary ammonium groups. The pyridium membranes showed good electrochemical properties, comparable to those of the commercial membranes, with electrical resistances of less than 3.0 × 10−4 Ω·m2 in 0.5 mol dm−3 NaCl and high ionic permselectivities (the transport number of Cl− ions being 0.96). Moreover, water splitting indicated by the proton transport numbers of the membranes containing pyridinium or its derivates, were about two or three orders of magnitude lower than those of the commercial membranes (such as AM‐1) at the same current density because the resonance effect in the quaternary pyridinium groups contributed to their molecular stability.
Micellar dissolution and diffusion effects on adsorption dynamics of surfactants
Authors: Liao Ying‐Chih , Basaran Osman A. , Franses Elias I.
Published: April 2004

A one‐dimensional (1‐D) model for the diffusion‐controlled dynamic adsorption and surface tension in micellar solutions of nonionic surfactants is developed and tested with experimental data. The micellar dissolution rate for monodisperse micelles is described as being proportional to the micellar concentration and to the concentration difference between the critical micelle concentration (cmc) and the local monomer concentration with a micellar dissolution rate constant k. The Langmuir or Frumkin adsorption isotherms are used in a diffusion‐controlled adsorption model with micellar dissolution. The hydrodynamic effects due to interface generation in the experiments are simplified as resulting in a stagnant layer with an adjustable finite length l. The model is solved rigorously by the finite‐element method with a stretched grid and adaptive time step sizes. From simulations, the micellar dissolution rate is found to be much more important for dynamic adsorption than the micellar diffusion rate. Moreover, the size distribution of micelles is found to be insignificant for dynamic adsorption when a narrow distribution is considered. New equilibrium and dynamic surface‐tension data for a planar interface in a Langmuir trough has been obtained for two nonionic surfactants, straight‐chain alkyl ethylene oxides, C14E6 and C16E6, at concentrations below and above their cmc's. The pre‐cmc data are used to obtain the respective Langmuir isotherm parameters Γm,L and KL and the effective diffusion length l≈0.3 mm. With values of Γm,L, KL, and l determined from pre‐cmc data, the post‐cmc data are fitted fairly well with the micellar dissolution time constant τK≡1/kC* (C* is the cmc), which is 1.2 ms for C14E6 and 4.5 ms for C16E6.
Solubility of hydrogen in heavy n‐alkanes: Experiments and saft modeling
Authors: Florusse L. J. , Peters C. J. , Pàmies J. C. , Vega Lourdes F. , Meijer H.
Published: April 2004

New experimental measurements on the solubility of hydrogen in several normal alkanes, ranging from decane and up to hexatetracontane, are presented. Data cover a temperature range from 280 K to 450 K, and pressures up to 16 MPa were applied. Hydrogen solubilities of up to 30 mol % were measured. These mixtures are described through a molecular‐based equation of state based on the statistical associating fluid theory (SAFT). In the SAFT approach, all the compounds are modeled as homonuclear chains of united‐atom sites interacting through a Lennard‐Jones potential. Optimized values for the chain length, Lennard‐Jones diameter, and dispersive energy characterize the hydrogen molecule. In the case of n‐alkanes, a correlation for these molecular parameters is used. Two additional parameters, independent of the thermodynamic variables, were fitted to the experimental data of a single isopleth for each particular mixture. The agreement between the measured and predicted solubilities is excellent (overall AAD<1.5%) in all the thermodynamic range, and does not significantly worsen as the molecular weight of the compound increases.
Photosensitive poly(urethane acylsemicarbazide)s with azobenzene chromophores in the main chain
Authors: Palanisamy Aruna , Sundar Saimani , Radhakrishnan Ganga
Published: April 2004

Poly(urethane acylsemicarbazide)s were synthesized with a two‐step process: (1) the in situ generation of diisocyanate through the thermal decomposition of an azobenzene‐containing precursor diazide and a reaction with ester/ether polyols to form an isocyanate‐terminated prepolymer and (2) chain extension in N,N‐dimethylacetamide with aliphatic or aromatic dihydrazides. Films cast from N,N‐dimethylacetamide solutions were characterized with attenuated total reflection/Fourier transform infrared spectroscopy, and the thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. The effects of the hard‐segment content and chain extenders on the static and dynamic mechanical properties were investigated. The photoresponsive behavior of the polymers and the effects of variations in the chromophore concentration and chemical composition on the kinetics of photoisomerization were investigated with ultraviolet–visible spectroscopy, which revealed that the rates were independent of the chromophore concentration. The photomechanical behavior, assessed with creep‐recovery measurements, proved that the systems underwent photochemical isomerization upon irradiation with ultraviolet light. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 444–454, 2004
Investigation on the properties of a three‐component copolymer consisting of tris(allylphenoxy) triazine monomer and a diamine‐chain‐extension bismaleimide
Authors: Fang Qiang , Li Guang‐Zhe , Zeng Xuan , Jiang Lu‐Xia
Published: April 2004

A new type of modified bismaleimide resin was obtained by copolymerization between tris(allylphenoxy)triazine monomer (TAPT) and an aromatic diamine‐chain‐extension bismaleimide [e.g., 4,4′‐diaminodiphenylmethane (DADPM)‐chain‐extension 4,4′‐bismaleimidodiphenylmethane (BMDPM)]. The new three‐component‐polymer system had good processibility and mechanical properties. Better results were obtained when the weight ratio of TAPT to the DADPM‐chain‐extension BMDPM resin was 30%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 475–480, 2004
Validation of a GC‐MS screening method for anabolizing agents in solid nutritional supplements
Authors: Van Thuyne W. , Delbeke F. T.
Published: April 2004

A sensitive and selective method for the screening of 28 different compounds including testosterone and prohormones, nandrolone and prohormones, stanozolol and metandienone in solid nutritional supplements is described and validated. The different substances are extracted from the solid nutritional supplements by liquid–liquid extraction with a mixture of pentane and freshly distilled diethylether (9/1) after dissolving the supplement in NaOH (1 N). The anabolizing agents are derivatized with a mixture of MSTFA/NH4I/ethanethiol (320/1/2), routinely used for the derivatization of anabolic steroids extracted from urine. The TMS‐derivatives are analysed by GC‐MS in the SIM mode. The limits of detection were in the range from 2 to 40 ng/g. One supplement was analysed with this method and was found to contain several forbidden substances according to IOC doping regulations. All detected compounds, except dihydrotestosterone, could be conﬁrmed with GC‐MS2, proving that the proposed method is suitable for the screening of anabolizing agents in solid nutritional supplements. Copyright © 2004 John Wiley & Sons, Ltd.
A simple, rapid and sensitive method for simultaneous determination of rivastigmine and its major metabolite NAP 226‐90 in rat brain and plasma by reversed‐phase liquid chromatography coupled to electrospray ionization mass spectrometry
Authors: Enz Albert , Chappuis Alain , Dattler Andre
Published: April 2004

A simple and sensitive reversed‐phase liquid chromatography coupled with electrospray–mass spectrometry was developed and validated for the simultaneous determination of rivastigmine, a cholinesterase inhibitor, and its major metabolite NAP 226‐90 in rat plasma and brain homogenates. Rivastigmine and NAP 226‐90 were extracted from plasma and brain by ethyl acetate and, after drying under nitrogen, re‐dissolved in acetonitrile and separated isocratic by HPLC on a C18 column and quantiﬁed by single ion monitoring mass spectrometer. The mean (±SD) extraction efﬁciency for rivastigmine in plasma and brain was 93 ± 2 and 95 ± 2% (n = 5) of NAP 226‐90 in a drug range of 10–100 pmol/mL or pmol/g. The method proved to be linear within the tested range (regression coefﬁcient, r = 0.9999, n = 5). Intra‐ and inter‐day precision coefﬁcients of variation and accuracy bias were acceptable (within 15%, n = 5) over the entire range for both compounds using plasma or brain samples. The limits of quantiﬁcation were 0.5 pmol/mL plasma and 2.5 pmol/g brain for rivastigmine and 1 pmol/mL plasma and 5 pmol/g brain for NAP 226‐90, respectively. The analytical technique was used to determine the concentrations of rivastigmine and its metabolite NAP 226‐90 in rat plasma and brain after oral drug administration. The concentrations of the parent drug and its major metabolite were compared to a pharmacodynamic parameter, the ex vivo inhibition of acetylcholinesterase. Copyright © 2003 John Wiley & Sons, Ltd.
Identiﬁcation and determination of active anthraquinones in Chinese teas by micellar electrokinetic capillary chromatography
Authors: Zheng Wenjie , Wang Shufang , Chen Xingguo , Hu Zhide
Published: April 2004

The simultaneous determination of emodin, aloe‐emodin and rhein, in Semen Cassiae, Qinghai Wild Dahuang tea, Ningxia Juemingzi tea, Lanzhou Juemingzi tea and Surong Juemingzi tea, has been investigated by micellar electrokinetic capillary chromatography for the ﬁrst time. With an electrolyte containing 15 mm borax, 30 mm SDS, 10% (v/v) ethanol, at pH 9.60 and 20 kV applied voltage, the three analytes were completely separated within 12 min. The effects of the concentration of borax, electrolyte pH, the concentrations of SDS and organic modiﬁer and the applied voltage on electropheoretic behavior and separation were studied. The linear calibration range was 4–120 µg/mL (r = 0.9921) for emodin, 10–200 µg/mL (r = 0.9970) for aloe‐emodin and 2–100 µg/mL (r = 0.9971) for rhein, respectively. Under the optimum conditions, the relative standard deviation (RSD) values (n = 6) of the migration time and the peak area of each peak was 0.59–0.80% and 1.30–3.22%, respectively. The contents of the analytes in Rheum, Qinghai Wild Dahuang tea, Semen Cassiae and three other kinds of teas were easily determined with recoveries ranging from 95.3 to 104.4%. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of therapeutic and toxic doses of levamisole on thyroid hormones and some biochemical parameters in sheep
Authors: Atessahin Ahmet , Karahan Izzet , Pirincci Ibrahim
Published: April 2004

This study was carried out to establish the effects of therapeutic and toxic doses of levamisole on thyroid hormone levels and some biochemical parameters in sheep. Twelve Akkaraman ewes were used. Levamisole was given orally at doses of 7.5 mg kg−1 (group 1) and 40 mg kg−1 (group 2) to the animals. Blood samples were taken from the jugular vein at 2, 4, 8, 24, 48, 96 and 144 h after the administrations. Serum thyroid hormones and some biochemical parameters were determined on these samples. When compared with the control levels, no significant changes were observed in triiodothyronine (T3) and thyroxin (T4) levels in group 1. Although levamisole was found to increase the levels of total T3, it decreased the levels of total T4 in group 2. On the other hand, free T3 and free T4 levels were not changed in either group. While serum alkaline phosphatase (ALP) activities were decreased, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatinine kinase (CK) activities were increased significantly by levamisole. However, it increased the serum albumin and cholesterol levels, but decreased the inorganic phosphate levels in groups 1 and 2. On the other hand, when compared with the control levels, no significant changes were detected in serum sodium, potassium and calcium levels. In conclusion, therapeutic and toxic doses of levamisole were determined to affect thyroid metabolism and some biochemical parameters in sheep. Copyright © 2004 John Wiley & Sons, Ltd.
Catalytic Ionic Hydrogenations
Authors: Bullock R. Morris
Published: April 2004

Catalytic ionic hydrogenation of ketones occurs by proton transfer to a ketone from a cationic metal dihydride, followed by hydride transfer from a neutral metal hydride. This contrasts with traditional catalysts for ketone hydrogenation that require binding of the ketone to the metal and subsequent insertion of the ketone into a MH bond. Ionic hydrogenation catalysts based on the inexpensive metals molybdenum and tungsten have been developed based on mechanistic understanding of the individual steps required in the catalytic reaction.
Children's narratives and patterns of cardiac reactivity
Authors: Bar‐Haim Yair , Fox Nathan A. , VanMeenen Kirsten M. , Marshall Peter J.
Published: April 2004

The present study examines the associations between narrative processing, narrative production, and cardiac rate and variability in children. Heart period (HP) and vagal tone (VT) were computed for fifty‐eight 7‐year‐olds (29 males) during a resting baseline and during epochs in which the children listened to and completed a selected set of story‐stems from the MacArthur Story‐Stem Battery (I. Bretherton, D. Oppenheim, H. Buchsbaum, R. N. Emde, & the MacArthur Narrative Group, 1990). Significant decreases in HP and VT were observed between a resting baseline and epochs of story‐stem presentation by the experimenter. In addition, HP was shorter and VT lower during children's narrative production to emotionally laden story‐stems compared with narration to a neutral story‐stem. Furthermore, narrative and cardiac responses to stories containing separation–reunion themes reflected increased emotional and cognitive load compared with responses to stories that did not contain such themes. Finally, children who showed VT suppression in response to emotion‐laden stories produced more coherent and adaptive narratives compared to those of children who did not show VT suppression. The findings suggest interplay between the cognitive‐emotional processes associated with narrative processing and production and cardiac activation patterns. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 238–249, 2004.
Postnatal stress in mice: Does “stressing” the mother have the same effect as “stressing” the pups?
Authors: Moles A. , Rizzi R. , D'Amato F. R.
Published: April 2004

Short‐ and long‐term effects of brief maternal separation, maternal exposure to novel male odor, and standard rearing were compared in NMRI mice. The first condition consisted of 15 min of daily exposure of pups to clean bedding (CB), and the second condition consisted of 15 min of mothers' exposure to the odor of strange males (SM), for 14 days after birth starting from postnatal Day 1. Thus, both conditions entailed the same period of maternal separation. A control mother–offspring group was left undisturbed (nonhandled, N‐H). Corticosterone levels of mothers and pups were measured at the end of the last manipulation session. Corticosterone levels were higher in SM mothers, differing from both those of CB and of control dams; CB pups showed the highest corticosterone levels in comparison with the pups belonging to the other groups. Maternal behavior observed as furthest as possible from the daily separation session did not differ among the three groups. The behavioral response to 0.5 mg/kg of apomorphine in 15‐day‐old pups was enhanced in both CB and SM animals, which suggests an alteration of dopaminergic functioning. Finally, adult CB and SM male mice showed an increase in the percentage of time and entries into the open arms of the plus‐maze in comparison to nonhandled males. This study indicates that exposure to ecologically relevant stimuli elicited a stress response in lactating dams. This “social stress” brings about short‐ and long‐term effects in the offspring, even in the absence of any direct manipulation of the pups. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 230–237, 2004.
Study of the Behavior of an EC Mechanism Using Cyclic and Derivative Chronopotentiometric Techniques with Spherical Electrodes
Authors: López‐Tenés Manuela , Molina Juana María , Molina Ángela
Published: April 2004

The theory for an EC mechanism in chronopotentiometric techniques – reversal chronopotentiometry, cyclic chronopotentiometry and reciprocal derivative chronopotentiometry – is developed. The equations of this article are valid for spherical electrodes of any size and present a compact and easy‐to‐manage form. Methods for determining kinetic parameters of the chemical reaction are proposed and the influence of the electrode radius is discussed. We conclude that large errors in the determination of these parameters are committed if electrode sphericity is neglected. Reciprocal derivative chronopotentiometry has been applied in its traditional form (dt/dE vs. E), and in a more recently proposed modality consisting of plotting dt1/2/dE vs. E. These techniques are very convenient for studying an EC mechanism since the response is obtained in the form of peaks which are quantitatively related to the kinetic parameters of the chemical reaction. A comparison of the chronopotentiometric methods analyzed leads us to conclude that working curves based on the dt1/2/dE vs. E curves are more suitable to obtain accurate values of the rate constants of the chemical reaction.
Evaluation of the seismic performance of a three‐story ordinary moment‐resisting concrete frame
Authors: Han Sang Whan , Kwon Oh‐Sung , Lee Li‐Hyung
Published: April 2004

This study focuses on the seismic performance of Ordinary Moment‐Resisting Concrete Frames (OMRCF) designed only for gravity loads. For this purpose, a 3‐story OMRCF was designed in compliance with the minimum design requirements in the American Concrete Institute Building Code ACI 318 (1999). This model frame was a regular structure with flexure‐dominated response. A 1/3‐scale 3‐story model was constructed and tested under quasi‐static reversed cyclic lateral loading. The overall behavior of the OMRCF was quite stable without abrupt strength degradation. The measured base shear strength was larger than the design base shear force for seismic zones 1, 2A and 2B calculated using UBC 1997. Moreover, this study used the capacity spectrum method to evaluate the seismic performance of the frame. The capacity curve was obtained from the experimental results for the specimen and the demand curve was established using the earthquake ground motions recorded at various stations with different soil conditions. Evaluation of the test results shows that the 3‐story OMRCF can resist design seismic loads of zones 1, 2A, 2B, 3 and 4 with soil types SA and SB. For soil type SC, the specimen was satisfactory in seismic zones 1, 2A, 2B and 3. For soil type SD, the OMRCF was only satisfactory for seismic zones 1 and 2A. Copyright © 2004 John Wiley & Sons, Ltd.
Pregnancy‐associated plasma protein‐A (PAPP‐A) expression and insulin‐like growth factor binding protein‐4 protease activity in normal and malignant ovarian surface epithelial cells
Authors: Kalli Kimberly R. , Chen Bing‐Kun , Bale Laurie K. , Gernand Erica , Overgaard Michael T. , Oxvig Claus , Cliby William A. , Conover Cheryl A.
Published: April 2004

Pregnancy‐Associated Plasma Protein‐A (PAPP‐A) proteolyses insulin‐like growth factor binding protein‐4 (IGFBP‐4), thereby regulating local IGF availability. Reduced PAPP‐A mRNA expression has been reported in ovarian cancer specimens compared to normal ovarian surface epithelial cells (OSE). To characterize PAPP‐A expression and proteolytic activity in OSE, we developed a lifespan‐extended human cell model using a temperature‐sensitive mutant of the SV40 large T antigen (SV40LT). These OSE(tsT) cells proliferate at 34°C (i.e., when SV40LT‐positive), but not at 39°C, a temperature at which the SV40LT is unstable (SV40LT‐negative). Proteolysis of radiolabeled IGFBP‐4 in conditioned media from OSE(tsT) lines was IGF‐dependent and blocked by anti‐PAPP‐A antisera. Temperature shifts that eliminated stable SV40LT induced a 7‐fold increase in PAPP‐A mRNA and a 4‐fold increase in protein. The converse experiment (shifting to SV40LT‐positive conditions) resulted in decreased levels of PAPP‐A mRNA but little change in PAPP‐A protein. Nevertheless, there was a marked reduction in IGF‐BP‐4 proteolytic activity in medium of SV40LT‐positive OSE‐(tsT) cells. This decreased PAPP‐A activity coincided with a nearly 20‐fold increase in mRNA encoding a physiological inhibitor of PAPP‐A, the precursor form of eosinophil Major Basic Protein (proMBP), and 4‐ to 5‐fold increases in proMBP protein. Primary cultures of unmodified OSE expressed high levels of PAPP‐A and undetectable proMBP, and therefore produced abundant IGFBP‐4 protease activity. Short‐term ovarian tumor cell cultures expressed variable levels of PAPP‐A and high levels of proMBP, and consequently secreted little or no IGFBP‐4 protease activity. The concurrent regulation of PAPP‐A and its inhibitor, proMBP, suggests that IGFBP‐4 proteolysis and local regulation of IGF availability may be altered in malignant ovarian epithelial cells. © 2004 Wiley‐Liss, Inc.
Vaccination with hybrids of tumor and dendritic cells induces tumor‐specific T‐cell and clinical responses in melanoma stage III and IV patients
Authors: Trefzer Uwe , Herberth Gunda , Wohlan Karolina , Milling Annett , Thiemann Max , Sherev Tumenjargal , Sparbier Katrin , Sterry Wolfram , Walden Peter
Published: April 2004

Hybrid cell vaccination was developed as therapeutic approach that aims at stimulating tumor‐specific cytotoxic T‐cell responses in cancer patients using hybrids of autologous tumor and allogeneic dendritic cells. We tested this concept and the efficacy of the vaccines in inducing clinical and immunologic responses in a clinical trial with melanoma stage III and IV patients. Of the 17 patients evaluated, 1 experienced a complete response, 1 a partial response and 6 stable disease with remarkably long survival times. In 11 of 14 patients analyzed, high‐frequency T‐cell responses to various tumor‐associated T‐cell epitope were induced and detectable in the peripheral blood. These immune responses were detected in clinical response patients as well as nonresponders. Failures of clinical responses in all the cases investigated correlated with loss of antigen expression and presentation. Hybrid cell vaccination thus proves effective in inducing tumor‐specific T‐cell responses in cancer patients. © 2004 Wiley‐Liss, Inc.
Indian hedgehog signaling pathway: Expression and regulation in pancreatic cancer
Authors: Kayed Hany , Kleeff Jörg , Keleg Shereen , Guo Junchau , Ketterer Knut , Berberat Pascal O. , Giese Nathalia , Esposito Irene , Giese Thomas , Büchler Markus W. , Friess Helmut
Published: April 2004

Pancreatic cancer is an aggressive malignancy that exhibits a number of genetic and epigenetic alterations. Indian hedgehog (Ihh) and its 2 signaling receptors, patched (Ptc) and smoothened (Smo), are involved in pancreatic development and regulation of β‐cell function as well as in certain human tumors. In the current study, we analyzed the expression, distribution and function of Ihh and its receptors in pancreatic cancer. Quantitative RT‐PCR and immunohistochemistry were utilized to analyze the expression, localization and transcriptional regulation of Ihh, Ptc and Smo. The effects of inhibition and stimulation of the hedgehog signaling pathway on pancreatic cancer cell growth were examined by the MTT cell growth assay. By quantitative RT‐PCR, Ihh, Ptc and Smo mRNA levels were increased 35‐, 1.2‐ and 1.6‐fold, respectively, in pancreatic cancer tissues in comparison to normal pancreatic tissues. By immunohistochemistry, Ihh, Ptc and Smo were expressed in the islet cells of normal and cancerous tissues and in pancreatic cancer cells. The growth of pancreatic cancer cells was dose‐dependently inhibited by the hedgehog antagonist cyclopamine through G0/G1 arrest. In contrast, Ihh agonists exhibited no significant effect on pancreatic cancer cell growth. TGF‐β1 repressed Ihh transcription in a TGF‐β1‐responsive pancreatic cancer cell line, but had no effect on the other tested cell lines. In conclusion, Ihh and its receptors Ptc and Smo are expressed in pancreatic cancer, and blockage of hedgehog signaling results in inhibition of pancreatic cancer cell growth, suggesting that aberrant activation of the Ihh signaling pathway contributes to tumor development in this malignancy. © 2004 Wiley‐Liss, Inc.
Business‐to‐business electronic marketplaces: Joining a public or creating a private
Authors: Milliou Chrysovalantou , Petrakis Emmanuel
Published: April 2004

We analyse a firm's incentives to create a private B2B e‐marketplace or to join a public e‐marketplace. In the former the firm incurs higher set‐up costs but lower quality investment costs due to closer supplier–buyer collaboration than in the public. In the latter, the firm's quality improvement may spillover to competitors. We show that a firm's incentives to create a private e‐marketplace are stronger, the closer is supplier–buyer collaboration, the higher are spillovers, and the larger is the buyer's profit share within the e‐marketplace. Our welfare analysis indicates that a firm's incentives do not always coincide with those of a social planner. Copyright © 2004 John Wiley & Sons, Ltd.
Optimal (4up, 5, 1) optical orthogonal codes
Authors: Chang Yanxun , Ji L.
Published: April 2004

By a (ν, k, 1)‐OOC we mean an optical orthogonal code. In this paper, it is proved that an optimal (4p, 5, 1)‐OOC exists for prime p ≡ 1 (mod 10), and that an optimal (4up, 5, 1)‐OOC exists for u = 2, 3 and prime p ≡ 11 (mod 20). These results are obtained by applying Weil's theorem. © 2004 Wiley Periodicals, Inc.
On the existence of a PBD(30,{4,5,7,8*})
Authors: Grüttmüller Martin , Streso Katy
Published: April 2004

In the present paper, we will prove by an exhaustive search method that a pairwise balanced design on 30 points with blocks of size 4,5,7 and exactly one block of size 8 does not exist. © 2004 Wiley Periodicals, Inc. J Combin Designs 12: 271–278, 2004.
Evaluation of a modified IAT‐gel with polyethylenglycol (PEG) addition method for red blood cell antibody identification
Authors: Gustafsson L. , Wikman A. , Lundahl J.
Published: April 2004

We aimed to evaluate whether a PEG‐IAT method, modified for gel technique, could replace the two‐stage enzyme method for routine identification of red blood cell (RBC) antibodies.

A total of 161 selected patient samples were analyzed with the two‐stage enzyme tube technique and the PEG‐IAT in gel techniques. In 65 samples, identical antibody results were obtained by the two methods. An additional 28 antibodies were identified by either the PEG‐IAT gel method or the enzyme method. Twenty antibodies were identified by the PEG‐IAT gel method only (12 Rh antibodies, four anti‐Kell, two anti‐Fya, two anti‐Jka), and eight antibodies by the enzyme method only (four Rh antibodies, one anti‐K, one anti‐Jka, two anti‐Lea). The results in the remaining 68 samples were judged as nonspecific reactions, which were more common when the enzyme method was used.

We concluded that the PEG‐IAT in gel method identifies more RBC antibodies with less nonspecific reactions than the two‐stage enzyme technique. However, no single method detected all clinical significant RBC antibodies. J. Clin. Lab. Anal. 18:165–169, 2004. © 2004 Wiley‐Liss, Inc.
Surface‐enhanced laser desorption/ionization‐time of flight‐mass spectrometry (SELDI‐TOF‐MS): A new proteomic urinary test for patients with urolithiasis
Authors: Cadieux Peter A. , Beiko Darren T. , Watterson James D. , Burton Jeremy P. , Howard Jeffrey C. , Knudsen Bodo E. , Gan Bing Siang , McCormick John K. , Chambers Ann F. , Denstedt John D. , Reid Gregor
Published: April 2004

SELDI‐TOF‐MS is a highly sensitive protein‐analysis tool capable of detecting minute protein profile differences between biological samples. As proteins have been associated with urinary tract calculi, protein‐based urinalysis may offer insights into their diagnosis. The purpose of this study was to evaluate SELDI‐TOF‐MS as a potential method for identifying urinary biomarkers of urolithiasis.

Midstream sterile urine samples were obtained from 25 male patients with a confirmed diagnosis of urolithiasis (test group) and 25 male subjects with no known history of the disease (controls). Urinary levels of oxalate, total protein, albumin, and osteopontin were determined. Protein profiles were generated using SELDI‐TOF‐MS.

SELDI‐TOF‐MS profiling revealed a relationship between protein peak intensities at 67 and 24 kDa that differed between the two groups. The ratio of p67:p24 was found to be less than 1.0 in all of the control samples (mean 0.26), while 18 out of 25 (72%) of the test group samples displayed a ratio greater than 1.0 (total group mean 4.75, P<0.001). Albumin, total protein, and oxalate levels were higher in the test group than the controls.

Although SELDI‐TOF‐MS is not yet in widespread use in hospital and diagnostic laboratories, this system represents a promising new method for rapidly identifying patients with urolithiasis. J. Clin. Lab. Anal. 18:170–175, 2004. © 2004 Wiley‐Liss, Inc.
Single cell PCR from archival stained bone marrow slides: A method for molecular diagnosis and characterization
Authors: Zanssen Stefanie
Published: April 2004

Molecular analysis of isolated single cells is a powerful tool for clarifying issues of cell origin and clonality. Previous reports have described PCR amplifications from total DNA and RNA extracted from archival bone marrow and peripheral blood smears and have also shown the feasibility of amplifications from single cells, microdissected from stained histological sections. In this study, a method is described for performing PCR from morphologically defined single cells isolated from archival May‐Gruenwald‐Giemsa‐stained bone‐marrow and blood smears. Using three DNA extraction procedures, the organic lysis showed reproducible high efficiencies of amplifications. With this method, we were able to amplify long range amplicons up to 14.5 kb from mitochondrial DNA as well as PCR products of conventional length. The usability of such products for molecular diagnosis is demonstrated by restriction fragment length polymorphism (RFLP)characterization of a mitochondrial disorder. In conclusion, this method has the power to perform molecular diagnosis and characterization of diseases on the single cell level, and should provide valuable information to aid disease treatment and prognosis of hematological disorders. J. Clin. Lab. Anal. 18:176–181, 2004. © 2004 Wiley‐Liss, Inc.
Environment‐dependent down‐modulation of CD45 cell surface expression on polymorphonuclear cells
Authors: Böhm Ingrid
Published: April 2004

CD45, a transmembrane protein tyrosine phosphatase, regulates important cell functions. Its involvement in clearing tissues from dead or dying cells by polymorphonuclear cells (PMNs) is unclear. Therefore, in this study the influence of exogenous factors (e.g., temperature and phagocytosis) on the CD45 expression on PMNs (in patients with lupus erythematosus (LE) vs. controls) was analysed by flow cytometry. The data showed a significant down‐regulation of CD45 at 4°C in controls, but not on LE‐PMNs. In the presence of targets, CD45 was significantly decreased (P<0.00002). Substrate‐dependent down‐regulation was greater in the presence of nuclei than in the presence of dead cells(68.98%±2.28% vs. 47.89%±2.75%; P<0.002), and on LE‐PMNs than on control‐PMNs (45.93%±4.92% vs. 53.65%±2.2%). Target pretreatment with anti‐dsDNA antibody‐containing serum resulted in a lower CD45 expression compared to treatment with normal serum. This effect was more pronounced on PMNs of LE patients than on those of controls. Phagocytosis was inversely correlated with CD45 expression (P<0.0007). These data suggest that phagocytic clearance of cellular debris by PMNs may modulate the function of the effector cells, and that anti‐dsDNA antibodies apparently enhance the phagocytic clearance. J. Clin. Lab. Anal. 18:187–194, 2004. © 2004 Wiley‐Liss, Inc.
Alkaline sulfite/anthraquinone pulping of pine wood chips biotreated with Ceriporiopsis subvermispora
Authors: Mendonça Régis , Ferraz André , Kordsachia Othar , Patt Rudolf
Published: April 2004

Pine wood chips were treated for 30 days with Cemporiopsis subvermispora in 20 dm3 bioreactors. A typical selective biodelignification was observed. The biotreated wood chips and undecayed controls were subjected to modified alkaline sulfite/anthraquinone (ASA) cooking at 170 °C or 175 °C applying varying cooking times ranging from 30 to 270 min. In all cases, the residual lignin content of the pulps prepared from biologically pretreated wood chips was lower than that of the control pulp. With increasing cooking time, however, the differences in kappa number became smaller. Wood chips cooked for a short time required mechanical refining for fiber liberation. A disk‐refining step resulted in pulps with low reject content (0.4%) and high screened yield (56–60%). In this case, the use of biotreated wood chips provided pulps with significantly lower kappa numbers than for the control pulp (71 and 83, respectively). The pulp from biologically pretreated wood fibrillated rapidly, reaching 20° SR in only 38 min beating time in a Jokro mill, while the control pulp required 56 min to reach the same beating degree. Although easier to beat, the biopretreated pulps showed tensile and burst indices similar to those of the control samples. However, their tear indices were always lower. Easier delignification after wood biotreatment was not observed for the reactions performed at long cooking times. Oxygen delignification of biotreated and conventional ASA pulps with low kappa numbers reduced kappa number and improved brightness considerably with the biotreated pulps being favored by a better preservation of viscosity. Copyright © 2004 Society of Chemical Industry