bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spread and rebound of liquid droplets upon impact on flat surfaces
Authors: Mao Ted , Kuhn David C. S. , Tran Honghi 
Published: June 2004

AbstractThe spread and rebound of droplets upon impact on flat surfaces at room temperature were studied over a wide range of impact velocities (0.5–6 m/s), viscosities (1–100 mPa.s), static contact angles (30–120°), droplet sizes (1.5–3.5 mm), and surface roughnesses using a fast‐shutter‐speed CCD camera. The maximum spread of a droplet upon impact depended strongly on the liquid viscosity and the impact velocity. The tendency of a droplet to deposit or to rebound is determined primarily by the liquid viscosity and the liquid/substrate static contact angle. A model more broadly applicable than existing models was developed to predict maximum spread as a function of the Reynolds number, the Weber number, and the static contact angle. Based on the conservation of energy, a rebound model is proposed that predicts the tendency to rebound as a function of maximum spread and static contact angle.The maximum‐spread model prediction agrees to within 10% with more than 90% of the experimental data from different sources. In the current study, the rebound model successfully predicts the tendency of a droplet to rebound.
Film profiles behind liquid slugs in gas‐liquid pipe flow
Authors: Cook Martin , Behnia Masud 
Published: June 2004

AbstractA comprehensive one‐dimensional fully coupled hydrodynamic treatment of the film profiles behind liquid slugs in horizontal and inclined gas‐liquid slug flow is presented. Experiments were performed in horizontal air‐water pipes 32 and 50 mm in diameter, the smaller also being inclined to an angle of 5 degrees. Time traces of film thickness were produced with the use of a wire‐probe technique. The experimental results are compared against the theory presented here, as well as previously reported hydrodynamic models. It is concluded that the film profiles calculated by the use of one‐dimen‐sional models are highly sensitive to the choice of input variables, for example, the slug translational velocity; however, good agreement is achievable provided that consistent hydrodynamic equations and correct input variables are used. It is hoped that the work presented here will influence future mechanistic models of slug flow.
Hydrogen peroxide decomposition in supercritical water
Authors: Croiset Eric , Rice Steven F. , Hanush Russell G. 
Published: June 2004

AbstractThis work determines the rate constant of hydrogen peroxide decomposition in supercritical water. Experiments were conducted at pressures ranging from 5.0 to 34.0 MPa and for temperatures up to 450°C. The rate of the homogeneous decomposition reaction is distinguished from the rate of the catalytic decomposition on the reactor surface by conducting experiments at different surface‐to‐volume ratios. The rate constant of H2O2 decomposition follows the expression k(s−1) = 1013.4 ± 1.2 exp[(− 180 ± 16 kJ/mol)/RT], providing a higher value than that derived from RRKM calculations. Comparison between experiments at supercritical conditions (P = 24.5 and 34.0 MPa) and experiments in high‐pressure steam (P = 5.0 and 10.0 MPa) show that the efficiency of the catalytic surface reactions decreases significantly under supercritical conditions. The rate constant just mentioned was incorporated into a methanol oxidation model and the new prediction is compared with the experimental data of Rice et al. (1996), showing a distinct improvement compared to the original prediction.
Prediction of binary diffusion coefficients of solutes in supercritical solvents
Authors: He Chao‐Hong 
Published: June 2004

AbstractNew correlations, based on the rough hard‐sphere theory and an extensive literature database, were developed for the determination of the binary diffusion coefficients of liquid and solid solutes in supercritical solvents. The correlations were tested to predict 107 solute‐solvent systems with good results. The input data required for the correlations are the solute molecular weight, temperature, density and the solvent basic properties (molecular weight, critical volume, and critical pressure).
Catalytic and gas–solid reactions involving HCN over limestone
Authors: Jensen Anker , Johnsson Jan Erik , Dam‐Johansen Kim 
Published: June 2004

AbstractIn coal‐fired combustion systems solid calcium species may be present as ash components or limestone added to the combustion chamber. In this study heterogeneous reactions involving HCN over seven different limestones were investigated in a laboratory fixed‐bed quartz reactor at 873–1,173 K. Calcined limestone is an effective catalyst for oxidation of HCN. Under conditions with complete conversion of HCN at O2 concentrations above about 5,000 ppmv the selectivity for formation of NO and N2O is 50–70% and below 5%, respectively. Nitric oxide can be reduced by HCN to N2 in the absence of O2 and to N2 and N2O in the presence of O2. At low O2 concentrations or low temperatures, HCN may react with CaO, forming calcium cyanamide, CaCN2. The selectivities for formation of NO and N2O from oxidation of CaCN2 is 20–25% for both species. The catalytic activity of limestone for oxidation of HCN decreases with increasing degree of sulfation. Simultaneously the selectivity for formation of NO decreases while tht for N2O increases. The catalytic activity of sulfated limestone in‐creases with decreasing SO2 concentration, indicating a competition between SO2 and HCN for sites on the surface. The results indicate that heterogeneous oxidation of HCN is important in calciners and fluidized‐bed combustors with limestone addition or when burning coals with an ash with a high catalytic activity.
Predicting filtration time and maximizing throughput in a pressure filter
Authors: Landman Kerry A. , White Lee R. 
Published: June 2004

AbstractThe modeling of pressure filtration of flocculated suspensions using compressional rheology and a knowledge of compressional yield stress Py(ϕ) and a hydraulic resistance factor r(ϕ)(ϕ is the local volume fraction of solids) is shown to yield an initial solids loading that maximizes the throughput of the filter. The optimal initial height h0 is such that the filtration time to reach a specified average volume fraction as output equals the handling time for the filter press. The maximum throughput of the press is then examined as a function of the remaining control parameters, the initial solids volume fraction ϕ0, and the applied piston pressure δP. The dependence of filtration time on ϕ0/∞00 (where ϕ∞is the volume fraction of solids at infinite time under applied pressure δP) enables the construction of a simple numerical model for the pressure filtration process, which accurately approximates predictions of the full compressional rheology model.
Distribution kinetics of radical mechanisms: Reversible polymer decomposition
Authors: Kodera Yoichi , McCoy Benjamin J. 
Published: June 2004

AbstractFor polymers and other homologous mixtures that span a molecular weight (MW) range, many reaction mechanisms involve the formation, addition and decomposition of free radicals. In the chain reactions of polymerization and depolymerization, radicals and polymer molecules interact by a variety of primary reactions. We postulate that these radicals and molecules can be described by continuous molecular weight distributions (MWDs). Their chemical interactions are developed from generic, reversible addition or bond scission reactions. Distribution balance equations are proposed for initiation‐termination and propagation‐depropagation reactions, such as hydrogen abstraction, disproportionation, chain cleavage, and radical coupling. A comprehensive model including all these events conforms to the special mechanisms for chain‐end depolymer‐ization and for random‐scission polymer degradation. The evolution of an MWD from initial state to final equilibrium is described by the time dependence of MW moments. Irreversible degradation or polymerization relationships are obtained as limiting cases. First‐order rate constants observed in pyrolysis and thermolysis reactions are composed of algebraic groups of primary reaction rate constants.
IMA chromatography of a cell extract: Effect of loading pH on protein purification
Authors: Patwardhan Anshuman V. , Ataai Mohammad M. 
Published: June 2004

AbstractImmobilized metal ion affinity chromatography has shown promise for isolating desired proteins from host cell extracts, based on differential affinities for chelated metal ions. This article focuses on modeling the effect of loading pH on the purity and binding capacity of target proteins, during their separation from the cell extract of Escherichia coli, using immobilized copper affinity chromatography. Early chromatography experiments revealed that cellular proteins of E. coli elute in two separate peaks from an immobilized copper column under a decreasing pH step gradient. Thus, the cell extract is modeled by a mixture of two proteins, tuna heart cytochrome c and chicken egg white lysozyme. Transport and binding parameters of these proteins are evaluated over a wide pH range and used in a mathematical model of multicomponent chromatography. Target proteins are chosen such that they elute at a pH between the elution pH of cytochrome and lysozyme. Simulation results showed that decreasing the loading pH to a value between the elution pH of the weaker copper binding proteins of E. coli and that of the target protein may not only decrease the amount of E. coli proteins bound in the column but lead to a substantially higher binding capacity for the target protein.
Dynamics of foam films in constricted pores
Authors: Singh Gurmeet , Hirasaki George J. , Miller Clarence A. 
Published: June 2004

AbstractHydrodynamics of foam films in a porous medium depend strongly on the pore geometry, foam quality, foam flow rate, surfactant formulation, rheological properties of the film, and the capillary pressure in the medium. These dynamics were studied numerically by simulating the behavior of a foam film as it traverses a periodically constricted sinusoidal pore. Different regions of film behavior exist depending on its rheological properties. For a film with rigid (immobile) surfaces, the entrainment effect leads to a thickening film consistent with related phenomena such as Bretherton's (1961) analysis of a bubble moving in a capillary tube. A film with mobile surfaces, however, stretches and thins while remaining uniform in thickness and may become unstable under certain conditions. The dependence of limiting capillary pressure on the foam flow rate and rheological properties is explained quantitatively.
Synthesis and characterization of novel odd–even nylons based on eicosanedioic acid
Authors: Cui Xiaowen , Yan Deyue 
Published: June 2004

AbstractA series of novel odd–even nylons based on eicosanedioic acid, including nylons 11/20, 9/20, 7/20, 5/20, and 3/20, were prepared through step‐heating melting polycondensation with various diamines, and the products were comprehensively characterized. The results of FTIR, Raman spectra, NMR, and elemental analysis confirmed that the synthesized polyamides had the expected chemical structures. The viscosity‐average molecular weights of the obtained polyamides were in the range of 6.0 × 103–1.4 × 104. The melting points of the nylons, determined by differential scanning calorimetry, changed from 167 to 194°C. Thermogravimetric analysis gave the decomposition temperatures of the obtained nylons at about 460°C, except for nylon 3/20. Furthermore, dynamic mechanical analysis (DMA) was applied to nylons 11/20, 9/20, 7/20, and 5/20. The glass‐transition temperatures, measured by DMA, ranged from 29 to 52°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2066–2071, 2004
Thermal and thermo‐oxidative degradation properties of poly(benzimidazole amide imide) copolymers
Authors: Wang Huei‐Hsiung , Wu Shu‐Ping 
Published: June 2004

AbstractIn this study, 3,3′‐dinitrobenzidine was first reacted with excess isophthaloyl chloride to form a monomer with dicarboxylic acid end groups. Two types of aromatic dianhydride, [viz., pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐sulfonyldiphthalic anhydride (DSDA)] also were reacted with excess 4,4′‐diphenyl‐ methane diisocyanate (MDI) to form polyimide prepolymers terminated with isocyanate groups. The prepolymers were reacted further with the diacid monomer to form a nitro group–containing aromatic poly(amide imide) copolymers. The nitro groups in these copolymers were hydrogenated to form amine groups and cyclized at 180°C to form the poly(benzimidazole amide imide) copolymers in polyphosphoric acid (PPA), which acts as a cyclization agent. From the viscosity measurements, copolymer appeared to be a reasonably high molecular weight. From the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements it was shown that the glass transition temperature of copolymers was in the range of ∼270–322°C. The 10% weight loss temperatures were in the range of 460 ∼ 541°C in nitrogen and ∼441–529°C in air, respectively. The activated energy and the integration parameter of degradation temperature of the copolymers were evaluated with the Doyle‐Ozawa method. It indicated that these copolymers have good thermal and thermo‐oxidative stability with the increase in imide content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2072–2081, 2004
Prospects and implications of using chromatin insulators in gene therapy and transgenesis
Authors: Recillas‐Targa Félix , Valadez‐Graham Viviana , Farrell Catherine M. 
Published: June 2004

AbstractGene therapy has emerged from the idea of inserting a wild‐type copy of a gene in order to restore the proper expression and function of a damaged gene. Initial efforts have focused on finding the proper vector and delivery method to introduce a corrected gene to the affected tissue or cell type. Even though these first attempts are clearly promising, seveal problems remain unsolved. A major problem is the influence of chromatin structure on transgene expression. To overcome chromatin‐dependent repressive transgenic states, researchers have begun to use chromatin regulatory elements to drive transgene expression. Insulators or chromatin boundaries are able to protect a transgene against chromatin position effects at their genomic integration sites, and they are able to maintain transgene expression for long periods of time. Therefore, these elements may be very useful tools in gene therapy applications for ensuring high‐level and stable expression of transgenes. BioEssays 26:796–807, 2004. © 2004 Wiley Periodicals, Inc.
A gene for speed? The evolution and function of α‐actinin‐3
Authors: MacArthur Daniel G. , North Kathryn N. 
Published: June 2004

AbstractThe α‐actinins are an ancient family of actin‐binding proteins that play structural and regulatory roles in cytoskeletal organisation and muscle contraction. α‐actinin‐3 is the most‐highly specialised of the four mammalian α‐actinins, with its expression restricted largely to fast glycolytic fibres in skeletal muscle. Intriguingly, a significant proportion (∼18%) of the human population is totally deficient in α‐actinin‐3 due to homozygosity for a premature stop codon polymorphism (R577X) in the ACTN3 gene. Recent work in our laboratory has revealed a strong association between R577X genotype and performance in a variety of athletic endeavours. We are currently exploring the function and evolutionary history of the ACTN3 gene and other α‐actinin family members. The α‐actinin family provides a fascinating case study in molecular evolution, illustrating phenomena such as functional redundancy in duplicate genes, the evolution of protein function, and the action of natural selection during recent human evolution. BioEssays 26:786–795, 2004. © 2004 Wiley Periodicals, Inc.
Ups and downs of tissue and planar polarity in plants
Authors: Grebe Markus 
Published: June 2004

AbstractThe polar orientation of cells within a tissue is an intensively studied research area in animal cells. The term planar polarity refers to the common polar arrangement of cells within the plane of an epithelium. In plants, the subcellular analysis of tissue polarity has been limited by the lack of appropriate markers. Recently, research on plant tissue polarity has come of age. Advances are based on studies of Arabidopsis patterning, cell polarity and auxin transport mutants employing the coordinated, polar localization of auxin transporters and the planar polarity of root epidermal hairs as markers. These approaches have revealed auxin transport and response, vesicular trafficking, membrane sterol and cytoskeletal requirements of tissue polarity. This review summarizes recent progress in research on vascular tissue and planar epidermal polarity in the Arabidopsis root and compares it to findings on planar polarity in animals and cell polarity in yeast. BioEssays 26:719–729, 2004. © 2004 Wiley Periodicals, Inc.
Scavenger effect of ﬂavonols on HOCl‐induced luminol chemiluminescence
Authors: Selloum Laïd , Djelili Hanifa , Sebihi Laïla , Arnhold Juergen 
Published: June 2004

AbstractHypochlorous acid (HOCl), the main product of the myeloperoxidase system, is a strong oxidant and a potent chlorinating agent, which can damage host tissues. In the present work, the scavenger effect of three aglycone ﬂavonols (myricetin, quercetin and kaempferol) and of the natural glycoside ﬂavonol, rutin, was studied towards HOCl using luminol‐dependent chemiluminescence (CL). At 1 µmol/L ﬁnal concentration, rutin was the most powerful scavenger of HOCl with an inhibitory luminol oxidation of 91.4% ± 3.2%. Quercetin, kaempferol and myricetin inhibited the luminol‐dependent CL at the same concentration only by 75.9% ± 3.4%, 57.7% ± 5.3% and 43.3% ± 3.5%, respectively. With increasing concentration of these ﬂavonols, a dose‐dependent inhibition of luminol CL was observed. In order to prove to what extent ﬂavonols scavenge HOCl, their concentrations that gave 50% inhibition of luminescence (IC50) were compared to IC50 values of the sulphur‐containing compounds N‐acetyl cysteine (NAC) and taurine. The scavenging activities of compounds tested decrease in the order: rutin > NAC > quercetin > kaempferol > taurine. The present study revealed that rutin was the most effective scavenger agent. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of quercetin in human plasma after ingestion of commercial canned green tea by semi‐micro HPLC with electrochemical detection
Authors: Jin Dongri , Hakamata Hideki , Takahashi Kouji , Kotani Akira , Kusu Fumiyo 
Published: June 2004

AbstractDetermination of quercetin in human plasma was carried out by semi‐micro high‐performance liquid chromatography with electrochemical detection. Peak heights for quercetin were found to be linearly related to the amount of each quercetin injected from 1.5 to 750 pg. The detection limit (signal‐noise ratio, S/N = 3) of the present method for quercetin was 0.3 pg. Glucuronic and sulfate forms of quercetin in plasma were hydrolyzed enzymatically using β‐glucuronidase and sulfatase, respectively. Quercetin in plasma and the hydrolyzed solution were extracted with ethyl acetate and determined by the present method. The time courses of concentrations of quercetin in human plasma showed maxima at 1–1.5 h after ingestion of 340 mL of commercial canned green tea. Copyright © 2004 John Wiley & Sons, Ltd.
The effects of Maras powder (smokeless tobacco) on oxidative stress in users
Authors: Kilinc Metin , Okur Erdogan , Kurutas Ergul Belge , Guler Fatma Inanc , Yildirim Ilhami 
Published: June 2004

AbstractMaras Powder (MP) is a special kind of smokeless tobacco widely used in the southeast region of Turkey especially in Kahramanmaras and Gaziantep and other southeastern cities. It is obtained from a tobacco species, Nicotiana rustica L and ash of oak or grapevine wood. Tobacco may increase oxidative stress, which is related to the products of the oxygen metabolism taking place in all cells. Cellular antioxidants, e.g. catalase (CAT), superoxide dismutase (SOD) and glucose 6‐phosphate dehydrogenase (G6PD) protect the cell against oxidative damage. An imbalance between the ROS and antioxidants in favour of ROS is described as oxidative stress. In this study, we aimed to investigate the effect of MP on antioxidant enzyme levels and lipid peroxidation. We measured malondialdehyde (MDA), CAT, SOD and G6PD levels in blood of 68 MP users and 30 healthy controls who did not use MP. CAT, SOD and G6PD levels were lower in MP users than in the controls. On the other hand, lipid peroxidation levels (MDA), one of the best indicators of cytological damage, was increased in MP users compared with the controls. The present study showed that MP increases oxidative stress, which may cause many systemic disorders, including arteriosclerosis. Copyright © 2004 John Wiley & Sons, Ltd.
TNF‐α and leptin in experimental liver fibrosis models induced by carbon tetrachloride and by common bile duct ligation
Authors: Bahçecıoğlu İbrahim Halil , Yalniz Mehmet , Ataseven Hüseyin , Bülbüller Nurullah , Keçecı Muzaffer , Demırdağ Kutbeddin , Özercan İbrahim , Üstündağ Bilal 
Published: June 2004

AbstractIn this study we investigated TNF‐α and leptin levels in two different liver fibrosis models induced by carbon tetrachloride (CCl4) and common bile duct ligation (CBDL). A total of 36 male rats of Albino‐Wistar strain were allocated to three groups. One of the groups was the control. The second group received 0.15 ml 100 g−1 CCl4 subcutaneously for 6 weeks, 3 days per week. The third group underwent common bile duct ligation (CBDL) and was monitored for 4 weeks. Histopathological investigation included fibrosis, steatosis and inflammation. Serum IL‐6 and TNF‐α levels were analysed by ELISA methods and leptin was analysed by RIA. Fibrosis and steatosis increased significantly in the CCl4 group in comparison with the CBDL group (p < 0.01; p < 0.001). Leptin and TNF‐α levels in CCl4 group were higher than those in the CBDL and control groups (p < 0.05). TNF‐α and leptin levels were not related to each another in either the CCl4 group or the CBDL group (r=0.22, p > 0.05; r=0.19, p > 0.05). The IL‐6 level was higher in the CCl4 group in relation to severity of inflammation (p < 0.05). TNF‐α and leptin levels were higher in animals with liver fibrosis induced by CCl4, than they were in those whose liver fibrosis was induced by common bile duct ligation. Leptin and TNF‐α may be less effective on the development of liver fibrosis in the group which underwent common bile duct ligation. Copyright © 2004 John Wiley & Sons, Ltd.
Short‐ and long‐term clinical outcome after various stent implantation: Overview of the results of uni‐ and multicenter stent registries
Authors: Gyöngyösi Mariann , Khorsand Aliashgar , Sperker Wolfgang , Strehblow Christoph , Wexberg Paul , Probst Peter , Siostrzonek Peter , Lang Irene , Sochor Heinz , Glogar Dietmar 
Published: June 2004

AbstractThe present study reports the results of the short‐ and long‐term outcomes of prospective uni‐ and multicenter stent registries: Palmaz‐Schatz (n = 140 patients), Ave‐Micro and GFX (n = 280), Multilink Duet (n = 340), Multilink Tetra (n = 192), and Carbo (n = 140) Stent Registries, as well as the predictors and angiographic cutoff points predicting major adverse cardiac events (MACE) after different stent implantations. Significant decrease in subacute stent thrombosis (from 2.9% to 0) and MACE (from 35% to 8.3%) occurred as the improved stents, optimized stent implantation technique, and new postintervention drug therapy were introduced. The changes of angiographic cutoff values (postintervention minimal lumen diameter and preintervention reference diameter: from 2.9 and 3.1 mm for Palmaz‐Schatz to 2.5 and 2.8 mm for Multilink Duet, Multilink Tetra, and Carbo stents) and clinical and angiographic factors predicting MACE indicated the change of traditional restenosis paradigm and that progress in clinical practice might be able to counterbalance unfavorable lesion and intervention‐related characteristics. Catheter Cardiovasc Interv 2004;62:331–338. © 2004 Wiley‐Liss, Inc.