bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrapure Dialysate Influences Serum Myeloperoxidase Levels and Lipid Metabolism
Authors: Honda Hirokazu , Suzuki Hiroki , Hosaka Nozomu , Hirai Yuki , Sanada Daisuke , Nakamura Mari , Nagai Hisako , Ashikaga Eijin , Matsumoto Kei , Mukai Masanori , Watanabe Makoto , Akizawa Tadao
Published: March 2009

Background: Ultrapure dialysate (UD) might contribute to improvements in the morbidity and mortality of hemodialysis (HD) patients. However, it is unclear whether increasing dialysate purity affects chronic inflammation, oxidative stress, and lipid abnormalities. Methods: In a prospective cohort study, 126 patients undergoing maintenance HD using conventional dialysate (CD) with one endotoxin cut filter were assigned to either continuation of the same HD or HD using UD (more purified dialysate). At baseline and 6 months we measured lipids, high-sensitive (hs)CRP, oxidative LDL-cholesterol, and myeloperoxidase. Results: Serum myeloperoxidase and hsCRP levels in the UD group were significantly decreased at 6 months compared with the CD group. Multivariate analysis showed that decreases in non-HDL-cholesterol and ApoB at 6 months were independently correlated with changes in myeloperoxidase. Conclusion: Endotoxin-free UD can improve the chronic inflammatory status, oxidative stress, and lipid abnormalities, suggesting a possible contribution to reduced cardiovascular disease risk and ultimately to lowered mortality in HD patients.
E2F4 Is Required for Early Eye Patterning
Authors: Ruzhynsky Vladimir A. , Furimsky Marosh , Park David S. , Wallace Valerie A. , Slack Ruth S.
Published: March 2009

Increasingly, studies reveal novel functions for cell cycle proteins during development. Here, we investigated the role of E2F4 in eye development. E2F4-deficient mouse embryos exhibit severe early eye patterning defects, which are evident from embryonic day 11.5 and characterized by aberrant shape of the optic cup, coloboma as well as abnormal eye pigmentation. Loss of E2F4 is associated with proximal-distal patterning defects in the optic vesicle. These defects are characterized by the expansion of optic stalk marker gene expression to the optic cup and reduced expression of ventral optic cup markers. These defects are associated with a split of Shh expression domain at the ventral midline of the forebrain and expansion of the Shh activity into the ventral optic cup. Despite these patterning defects, early neuronal differentiation and Shh expression in the retina are not affected by E2F4 deletion. Overall, the results of our studies show a novel role of E2F4 in the early eye development.
Cirrhosis ameliorates monocrotaline-induced pulmonary hypertension in rats
Authors: Le Pavec J. , Perros F. , Eddahibi S. , Decante B. , Dorfmuller P. , Sitbon O. , Lebrec D. , Humbert M. , Mazmanian M. , Herve P.
Published: March 2009

Common bile duct ligation (CBDL) induces biliary cirrhosis and pulmonary vasodilatation. We tested whether CBDL ameliorates monocrotaline (MCT)-induced pulmonary hypertension (PH) in rats.

Five groups of rats were studied: controls; rats dosed with MCT (60 mg·kg−1subcutaneously); CBDL; rats dosed with MCT followed by CBDL on day 7; and rats dosed with MCT followed by CBDL (day 7) andL-NAME therapy between days 24 and 28. 28-day survival was 26% in the MCT group and 72% in the MCT+CBDL group. Pulmonary vascular resistance measured on days 21 and 28 increased in the MCT and MCT+CBDL+L-NAME groups, but returned to normal in the MCT+CBDL group on day 28. Pulmonary artery (PA) medial hypertrophy persisted in MCT+CBDL rats. PA inflammation increased in MCT+CBDL rats, with accumulation of both intra- and perivascular macrophages. Exhaled nitric oxide (NO) levels decreased in the MCT group and increased in the MCT+CBDL group, which showed upregulation of inducible NO synthase and normal endothelial NO synthase. Blood endothelin (ET)-1 increased in CBDL, MCT, and MCT+CBDL rats. Levels of ETBreceptors increased and ETAreceptors decreased in the MCT+CBDL group, whereas the opposite changes occurred in the MCT group.

Biliary cirrhosis induces pulmonary vasodilation that ameliorates MCT-induced PH and improves survival. Upregulation of inducible NO synthase and ETBreceptor and downregulation of ETAreceptor may be involved.
Titrated mandibular advancementversuspositive airway pressure for sleep apnoea
Authors: Gagnadoux F. , Fleury B. , Vielle B. , Pételle B. , Meslier N. , N’Guyen X. L. , Trzepizur W. , Racineux J. L.
Published: March 2009

The aim of this study was to compare mandibular advancement device (MAd) therapy and continuous positive airway pressure (CPAP) for obstructive sleep apnoea/hypopnoea syndrome (OSAHS) after one-night polysomnographic (PSG) titration of both treatments.

59 OSAHS patients (apnoea/hypopnoea index (AHI): 34±13 events·h−1; Epworth scale: 10.6±4.5) were included in a crossover trial of 8 weeks of MAd and 8 weeks of CPAP after effective titration. Outcome measurements included home sleep study, sleepiness, health-related quality of life (HRQoL), cognitive tests, side-effects, compliance and preference.

The median (interquartile range) AHI was 2 (1–8) events·h−1with CPAP and 6 (3–14) events·h−1with MAd (p<0.001). Positive and negative predictive values of MAd titration PSG for treatment success were 85% and 45%, respectively. Both treatments significantly improved subjective and objective sleepiness, cognitive tests and HRQoL. The reported compliance was higher for MAd (p<0.001) with >70% of patients preferring this treatment.

These results support titrated MAd as an effective therapy in moderately sleepy and overweight OSAHS patients. Although less effective than CPAP, successfully titrated MAd was very effective at reducing the AHI and was associated with a higher reported compliance. Both treatments improved functional outcomes to a similar degree. One-night titration of MAd had a low negative predictive value for treatment success.
Assembly and mobility of exon–exon junction complexes in living cells
Authors: Schmidt Ute , Im Kang-Bin , Benzing Carola , Janjetovic Snjezana , Rippe Karsten , Lichter Peter , Wachsmuth Malte
Published: March 2009

The exon–exon junction complex (EJC) forms via association of proteins during splicing of mRNA in a defined manner. Its organization provides a link between biogenesis, nuclear export, and translation of the transcripts. The EJC proteins accumulate in nuclear speckles alongside most other splicing-related factors. We followed the establishment of the EJC on mRNA by investigating the mobility and interactions of a representative set of EJC factors in vivo using a complementary analysis with different fluorescence fluctuation microscopy techniques. Our observations are compatible with cotranscriptional binding of the EJC protein UAP56 confirming that it is involved in the initial phase of EJC formation. RNPS1, REF/Aly, Y14/Magoh, and NXF1 showed a reduction in their nuclear mobility when complexed with RNA. They interacted with nuclear speckles, in which both transiently and long-term immobilized factors were identified. The location- and RNA-dependent differences in the mobility between factors of the so-called outer shell and inner core of the EJC suggest a hypothetical model, in which mRNA is retained in speckles when EJC outer-shell factors are missing.
Treatment of Phenol Wastewater Using Hydroxyl Radical Produced by Micro‐Gap Discharge Plasma Technique
Authors: Yang Xianli , Bai Mindong , Han Fen
Published: March 2009

Hydroxyl radical produced by non‐equilibrium plasma, which was induced by micro‐gap dielectric barrier discharge, was used for the treatment of phenol wastewater. The advantage of this method was that chemicals and catalysts were not involved when hydroxyl radical was generated from water and oxygen. A proportional efficiency of phenol removal was observed with the hydroxyl radical increasing. The removal efficiency was higher in a basic condition than in an acidic condition, which was enhanced with the pH value of the solution increasing from 3.6 to 11.2. It was rational to adjust the pH value between 9.0 and 10.0. The removal efficiency of phenol was reduced when the conductivity of the solution increased from 0 to 200 μs · cm −1; the highest was found in the solution without Na 2CO 3. The UV spectral absorption in the process indicated that few organic compounds with a conjugated structure were included in the treated wastewater.
Network models of massive datasets
Authors: Boginski Vladimir , Butenko Sergiy , Pardalos Panos
Published: March 2009

We give a brief overview of the methodology of modeling massive datasets arising in various applications as networks. This approach is often useful for extracting non-trivial information from the datasets by applying standard graph-theoretic techniques. We also point out that graphs representing datasets coming from diverse practical fields have a similar power-law structure, which indicates that the global organization and evolution of massive datasets arising in various spheres of life nowadays follow similar natural principles.
Petri nets on the semantic web guidelines and infrastructure
Authors: Gasevic Dragan
Published: March 2009

This paper gives the Petri net ontology as the most important element in providing Petri net support for the Semantic Web. Available Petri net formal descriptions are: metamodels, UML profiles, ontologies and syntax. Metamodels are useful, but their main purpose is for Petri net tools. Although the current Petri-net community effort Petri Net Markup Language (PNML) is XML-based, it lacks a precise definition of semantics. Existing Petri net ontologies are partial solutions specialized for a specific problem. In order to show current Petri net model sharing features we use P3 tool that uses PNML/XSLT-based approach for model sharing. This paper suggests developing the Petri net ontology to represent semantics appropriately. This Petri net ontology is described using UML, Resource Description Framework (Schema) RDF(S) and the Web Ontology Language-OWL.
G-allele of Intronic rs10830963 inMTNR1BConfers Increased Risk of Impaired Fasting Glycemia and Type 2 Diabetes Through an Impaired Glucose-Stimulated Insulin Release
Authors: Sparsø Thomas , Bonnefond Amélie , Andersson Ehm , Bouatia-Naji Nabila , Holmkvist Johan , Wegner Lise , Grarup Niels , Gjesing Anette P. , Banasik Karina , Cavalcanti-Proença Christine , Marchand Marion , Vaxillaire Martine , Charpentier Guillaume , Jarvelin Marjo-Riitta , Tichet Jean , Balkau Beverley , Marre Michel , Lévy-Marchal Claire , Færch Kristine , Borch-Johnsen Knut , Jørgensen Torben , Madsbad Sten , Poulsen Pernille , Vaag Allan , Dina Christian , Hansen Torben , Pedersen Oluf , Froguel Philippe
Published: March 2009

OBJECTIVE

Genome-wide association studies have identified several variants within the MTNR1B locus that are associated with fasting plasma glucose (FPG) and type 2 diabetes. We refined the association signal by direct genotyping and examined for associations of the variant displaying the most independent effect on FPG with isolated impaired fasting glycemia (i-IFG), isolated impaired glucose tolerance (i-IGT), type 2 diabetes, and measures of insulin release and peripheral and hepatic insulin sensitivity.

RESEARCH DESIGN AND METHODS

We examined European-descent participants in the Inter99 study (n = 5,553), in a sample of young healthy Danes (n = 372), in Danish twins (n = 77 elderly and n = 97 young), in additional Danish type 2 diabetic patients (n = 1,626) and control subjects (n = 505), in the Data from the Epidemiological Study on the Insulin Resistance Syndrome (DESIR) study (n = 4,656), in the North Finland Birth Cohort 86 (n = 5,258), and in the Haguenau study (n = 1,461).

RESULTS

The MTNR1B intronic variant, rs10830963, carried most of the effect on FPG and showed the strongest association with FPG (combined P = 5.3 × 10−31) and type 2 diabetes. The rs10830963 G-allele increased the risk of i-IFG (odds ratio [OR] 1.64, P = 5.5 × 10−11) but not i-IGT. The G-allele was associated with a decreased insulin release after oral and intravenous glucose challenges (P < 0.01) but not after injection of tolbutamide. In elderly twins, the G-allele associated with hepatic insulin resistance (P = 0.017).

CONCLUSIONS

The G-allele of MTNR1B rs10830963 increases risk of type 2 diabetes through a state of i-IFG and not through i-IGT. The same allele associates with estimates of β-cell dysfunction and hepatic insulin resistance.
Abnormal Carbenes as Ligands in Transition Metal Chemistry: Curiosities with Exciting Perspectives
Authors: Albrecht Martin
Published: March 2009

This review compiles the advances achieved in our laboratories using abnormal and less heteroatom-stabilized carbenes as ligands for transition metal chemistry. Fundamental studies allowed the evaluation of the impact of this new class of ligands both electronically and sterically.
Based on these results, initial catalytic applications have been devised in the area of H–H and C–H bond activation, demonstrating the potential of abnormal carbenes as unique ligands for transition metals.
Kinetics and modeling of charge transfer polymerization of methyl methacrylate
Authors: Rao P. G. , Vijayaraghavan R. , Raghavan K. V. , Sai P.S.T.
Published: March 2009

The charge transfer polymerization of methyl methacrylate (MMA) in presence of n‐butyl amine (nBA) and carbon tetrachloride (CCl4) with dimethyl sulfoxide (DMSO) as solvent was experimentally investigated. The variables include concentrations of MMA, nBA, CCl4, DMSO and reaction temperature. The effect of these variables on monomer conversion, number and weight average molecular weights is discussed. A reaction mechanism is proposed and overall kinetics, propagation, chain transfer and termination constants are evaluated. A mathematical model is proposed for estimating monomer conversion, number and weight average molecular weights. The proposed model is validated using the kinetic constants and compared satisfactorily with experimental data of the present study. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Bestimmung des Diffusionskoeffizienten mittels Fließinjektionsanalyse
Authors: Kiefer J. , Leipertz A.
Published: March 2009

Vermischungsprozesse spielen in praktisch allen verfahrenstechnischen Anlagen eine wichtige Rolle. Im Bereich der Stoffdatenforschung ist es daher von großer Bedeutung, Parameter wie den molekularen Diffusionskoeffizienten zu bestimmen. Im Rahmen des Beitrags wird die Fließinjektionsanalyse (FIA) als Methode zur Messung des Diffusionskoeffizienten vorgestellt und am Beispiel des Lebensmittelfarbstoffes E150d (Ammoniumsulfit‐Zuckercouleur) erprobt.
The bubble behavior in the gas‐solids fluidized bed
Authors: Yutani N. , Fan L. T. , Ho T. C.
Published: March 2009

The bubbling frequency in a gas‐solids fluidized bed and its stochastic variation along the axial direction of the bed were determined by means of the capacitance method. The stochastic model proposed, more specifically a pure‐death process, appears to be capable of describing the resultant data well.
A general correlation for the minimum spouting velocity
Authors: Littman H. , Morgan M. H.
Published: March 2009

A new general correlation is presented for the minimum spouting velocity based on the annular pressure gradient at the top of the bed at minimum spouting. The correlation fits a wide range of experimental data to 11.6% on average. The normalized minimum spouting velocity ratio. umS/umF, is shown to be a function of three dimensionless parameters.
A probe for point velocities in slurry flows
Authors: Brown N. P. , Shook C. A. , Peters J. , Eyre D.
Published: March 2009

A probe and measuring system for determing local values of particle velocity in liquid‐solids mixtures has been constructed and tested. The probe uses the cross‐correlation principle. Its performance was found to depend upon the scale of the concentration fluctuations which occur in the flow. Probe geometry was also found to be of importance. Volumetric flowrate measurements indicated that an accuracy of 3% could be achieved.

The probe should be of value in the study of two‐phase flows.
Influence of forced feed composition cycling on the rate of ammonia synthesis over an industrial iron catalyst part I — Effect of cycling parameters and mean composition
Authors: Jain A. K. , Hudgins R. R. , Silveston P. L.
Published: March 2009

Studies have been carried out at 2.38 MPa total pressure and at 360 and 400°C of the synthesis of ammonia over a triply‐promoted iron catalyst (United Catalysts Inc.). Runs were carried out using a gradientless reactor in steady‐state and periodic modes, the latter employing forced composition cycling. The catalyst had a particle diameter of 0.30 mm; the resulting reaction rates were free from transport intrusions. The range of mean compositions for steady‐state measurements was from 0.1 to 0.9 mole fraction of hydrogen and for periodic operation from 0.5 to 0.9. The cycle‐split ratio (used to describe non‐uniform cycling) varied from 0.2 to 0.85. Effects of cycle period, mean composition, cycle‐split, and temperature were investigated. Instantaneous rate variations within the cycle are reported.

Results showed that the cycling mode of operation results in an improvement in the time‐average rate of ammonia formation of up to 30%, depending upon the choice of operating parameters. Some implications for the mechanism of ammonia synthesis under periodic operation are presented.
Hydrodynamics of a mobile bed contactor with ‘Low’ density packing particles of different shapes
Authors: Rama O. P. , Rao D. P. , Rao V. Subba
Published: March 2009

Experimental studies have been reported on pressure drop, liquid holdup, bed expansion and minimum fluidization velocity in a 0.15 m ID mobile bed of relatively low density (53–183 kg m−3) spherical and irregular shaped particles. The Kito‐Tabei‐Murata correlation has been adapted to fit the data on the liquid holdup and the pressure drop. The bed expansion was found to depend on the shape and density of the particles. It is shown that, in general, only a part of the liquid holdup in the bed is supported by the upward flow of gas. It was observed that in some regions the particles congregated at the wall, leaving a particle free core. The maps depicting these regions are presented.
An observation of microbial cell accumulation in a finned tube
Authors: Turakhia M. , Characklis W. G.
Published: March 2009

Biofouling in heat exchange equipment results in significant energy loss by increasing heat transfer resistance and fluid frictional resistance. This paper compares the deposition and distribution of attached microbial cells on a smooth tube and a tube with inner fins after 100 hours exposure. Preliminary results suggest a significantly different distribution of attached microbial cells on the finned tube.
Die swell experiments for newtonian fluids
Authors: Hill G. A. , Chenier C. L.
Published: March 2009

The swelling and shrinking of Newtonian jets issuing from circular orifices or slits are examined. Equations predicting the die swell ratio and downstream flow characteristics are developed. It is found that the cause of swelling at low Reynolds numbers is related to a negative pressure (below the free stream pressure) at the slit exit. The scatter of experimental data has been studied and the factors contributing to this phenomenon are discussed. The die swell ratios and jet shapes versus Reynolds number for Newtonian liquids issuing from tubes are empirically shown.
Design of transient experiments for identification of fixed bed thermal transport properties
Authors: Murray Larry E. , Reiff E. K.
Published: March 2009

The utility of using optimal input signals to improve the parametric information content in a transient experiment is explored. This work extends the statistical design concepts that have proven useful in steady state model building studies to a dynamic environment. The methodology is demonstrated for the identification of thermal transport properties in an adiabatic packed bed. The effects of the choice of measurements, initial parameter values and accuracies, and performance criteria are assessed. The results indicate that optimal dynamic experiments can offer considerable improvement over present practice.
Measurement of slurry concentration and flow rates in shell and tube slurry heat exchangers
Authors: Moujaes Samir F.
Published: March 2009

A study has been conducted on a slurry flow behavior in vertical tubes having diameters of one inch in an upflow mode. A tube sampling technique and an optical electronics method were developed to determine the slurry concentration and flow rates for flurries comprised of different size particles. These methods will be applied in cold flow simulation of a shell and tube slurry heat exchanger.
Mass transfer in aerated fermentation broths in a stirred tank reactor
Authors: ČIč R. Jure , Berovič M. , Steiner W. , Koloini T.
Published: March 2009

The volumetric mass transfer coefficients, kLa, measured in a pilot plant (0.1 m3) and an industrial (67.5 m3) fermentor during an actual fermentation process are presented. Problems related to the estimation of the phsyical properties as well as to the correlation of experimental data and to scale up procedures are discussed. Although the scale up factor was rather high, both sets of data could be represented by single correlation. Comparison of the experimental data with several available correlations demonstrated the need for pilot plant experiments and scale up procedures, since it is almost impossible to take into account all relevant system properties.
Solid hold‐up in bubble columns with suspended solid particles under continuous operation
Authors: Kojima H. , Iguchi A. , Asano K.
Published: March 2009

Solid hold‐up in bubble columns with suspended solid particles was studied experimentally under continuous slurry feed for the system, air–water–glass beads, in two columns of 55 mm and 95 mm in diameter. Experimental results agree well with the prediction made on the basis of the one‐dimensional dispersion model.
Analysis of the performance of a simulated counter‐current chromatographic system for fructose – glucose separation
Authors: Ching C. B. , Ruthven D. M.
Published: March 2009

The adsorptive separation of fructose from glucose has been carried out in a simulated counter‐current chromatographic system using Zerolit‐25SCR14 ion exchange resin in Ca++ form as the adsorbent. Rate and equilibrium constants have been determined from chromatographic retention time measurements. The performance of a simulated counter‐current system comprising ten identical columns connected in series has been investigated and it is shown that the behaviour of such a system may be approximately represented by a simple McCabe–Thiele model. The HETP in the counter‐current system is higher than would be expected for an ideal plug flow system, showing that axial mixing is important. The McCabe–Thiele analysis may be easily extended to a four section ‘Sorbex’ system and a preliminary assessment of the performance of such a unit is made on the basis of the kinetic and equilibrium parameters derived from the experimental study.
Adsorptive separation of Kr from N2 — Part I Adsorbent screening studies
Authors: Ruthven D. M. , Tezel F. H. , Devgun J. S. , Sridhar T. S.
Published: March 2009

Results of a chromatographic study of the adsorption of N2 and Kr on several molecular sieve adsorbents are reported. The objective was to find a suitable adsorbent for the removal of traces of radioactive Kr from the off‐gas from nuclear fuel reprocessing facilities. Of the adsorbents examined, de‐aluminated H‐mordenite shows the highest selectivity for Kr relative to N2 and appears to be a promising adsorbent for this separation. The presence of traces of NO2, a likely impurity in the off‐gas, was found to suppress the adsorption of N2 more than that of Kr, thereby increasing the separation factor (α ∼ 12). In most of the adsorbents investigated, intracrystalline diffusion was too fast to measure but for N2 in H‐mordenite, intracrystalline resistance was found to be significant and strongly dependent on the initial dehydration temperature.
The catalytic cracking of a fischer‐tropsch synthesis product
Authors: Kobolakis I. , Wojciechowski B. W.
Published: March 2009

The use of a feed mostly composed of linear alkanes ranging from C5 to C30 has made it clear that initiation of catalytic cracking does not proceed on very strong Bronsted sites with the liberation of hydrogen. It has also shown that cracking of the linear molecules probably occurs on the first active site inside a zeolite pore with the result that the products formed lie almost totally in the C4 to C10 range and are highly isomerized.
A turbulence closure model for dilute gas‐particle flows
Authors: Chen C. P. , Wood P. E.
Published: March 2009

A second order closure scheme is developed for the numerical prediction of isothermal, non‐reacting, mono‐dispersed, dilute gas‐particle turbulent shear flows. The model is based on the two‐equation (κ‐ϵ) turbulence model developed for calculating the analogous gas‐phase flows. Contrary to passive additives in a single phase flow, the particles will affect the turbulence structure of the continuous phase. Thus, the κ‐ϵ model has been modified to account for the presence of the dispersed particles. In particular, the particles increase the dissipation rate because of the relative velocity fluctuations between the two phases. New proposals for these added effects based on particle size and loading are added to these equations. The resulting model is used to compute the axisymmetric jet in its developing region. The calculated jet spreading rate, centre‐line velocity decay and entrainment rate are all in excellent agreement with published experimental data. Calculated turbulence quantities such as the kinetic energy and mean Reynolds shear stress are greatly reduced from their “clean jet” levels by the presence of the particles in good agreement with the available experimental data.
The mechanism of catalytic cracking of n‐alkenes on ZSM‐5 zeolite
Authors: Abbot J. , Wojciechowski B. W.
Published: March 2009

The catalytic cracking of n‐alkenes on ZSM‐5 zeolite at 405°C can occur both by a monomolecular mechanism and a bimolecular process. In the latter, cracking is preceeded by dimerization. We show that pentenes are cracked exclusively by the bimolecular process. The dominant cracking mechanism for n‐hexenes also requires initial dimerization, although a small proportion (<19%) of the total cracking may proceed by a monomolecular process. Cracking of n‐heptenes is predominantly monomolecular, with only 13% of the total occurring via an initial dimer formation. The cracking of n‐octenes and n‐nonenes can be interpreted by assuming a monomolecular mechanism only. Thus it appears that at 405°C olefins smaller than C6 are stable with respect to direct cracking and must dimerize before a species is formed which is unstable enough to crack.

No molecular hydrogen was produced in any of the cracking reactions reported here in the range of conversions studied.
Effect of substance‐dependent Ωac on vapor‐liquid equilibrium calculations
Authors: Adachi Yoshinori , Sugie Hidezumi , Lu Benjamin C.‐Y.
Published: March 2009

The role of the dimensionless quantity Ωa (= aPc/R2T) at the critical points of pure substances, Ωac, on the representation of binary vapor—liquid equilibrium values was investigated using a two‐parameter cubic equation of state together with conventional mixing rules.

A two‐Ωac method was proposed to improve the representation of the equilibrium values in the critical region by considering the value of Ωac substance dependent. The limitations of the proposed method was also presented.
Settling stability of coal slurries prepared by wet grinding in the szego mill
Authors: Koka V. R. , Papachristodoulou G. , Trass O.
Published: March 2009

Static sedimentation experiments on coal‐#2 oil and coal‐water slurries, wet ground in a Szego mill, were conducted. These slurries contain more flaky particles as compared to those conventionally ground.

Concentration and size distribution of the coal, diameter and height of the settling columns and settling time were the independent variables. Coal concentration and particle size distribution along the columns, and settling rates were measured.

Despite their particle shape differences, these slurries were similar to others in terms of settling stability due to particle flocculation.
Further aspects of powdered poplar wood liquefaction by aqueous pyrolysis
Authors: Boocock D. G. B. , Sherman K. M.
Published: March 2009

The liquefaction of powdered poplar wood by rapid pyrolysis in water at 350°C has been studied further. It differs significantly from the liquefaction of wood chips in that oil yields are improved by pressurisation of the reactor. Oil yields (chloroform soluble) are about 45 per cent and are sensitive to water/wood mass ratios and residence time. Gas, measured in a new handling system, is produced in 5–12 per cent mass yields and contains 86–90 per cent carbon dioxide and 10–13 per cent carbon monoxide. The oil and aqueous phases contain carboxylic acids (particularly acetic), phenols, cyclohexanones, cyclopentanones, benzyl alcohols and furfural.
Computer control of continuous immobilized cell penicillin fermentations: Simulation studies
Authors: Kalogerakis Nicolas , Unardos Theodor , Behie Leo A. , Svrcek William Y. , Gaucher G. Maurice
Published: March 2009

Immobilized cell technology provides a simple and promising alternative to submerged free cell fermentations for the production of antibiotics like penicillin‐G. Recently, our biotechnology group has successfully developed a three phase fluidized bed bioreactor that is capable of running in a continuous mode more than 600 h. As a direct follow‐up, we propose in this paper a simple process control system which will enable penicillin fermentations to run under any desired cell specific growth rate and penicillin concentration in the effluent stream. By implementing such a control scheme, the reactor productivity can be substantially increased, and hence, make continuous fermentations highly attractive economically.
Ethanol production by extractive fermentation – solvent identification and prototype development
Authors: Kollerup Finn , Daugulis Andrew J.
Published: March 2009

The in situ removal and recovery of inhibitory fermentation products by solvent extraction has numerous beneficial effects (increased reaction rate, fermentation of concentrated feeds, decreased water usage, etc.) which have been confirmed on theoretical grounds. For the development of such an extractive fermentation process, the identification of solvents having desirable physical properties as well as complete biocompatibility with the microorganism is an absolute prerequisite, which, to this point, has not been adequately met. By means of a computer data base, we have systematically screened 1,361 solvents for their suitability for use in an extractive ethanol fermentation, and, through subsequent experimental evaluation of 70 of these solvents, have identified 19 as being appropriate for use in a continuous extractive fermentation process.

Details of this screening procedure, and physico‐chemical data of the suitable extraction solvents are presented. A prototype extractive fermentation system, the first to employ a Continuous Stirred Tank Fermentor, is described. Results from mass transfer experiments in this prototype system, together with extractive fermentation experiments involving medium‐strength (ca. 150 g/L) glucose feeds are discussed.
Transient forced convection in laminar channel flow with stepwise variations of wall temperature
Authors: Cotta R. M. , Özişik M. N.
Published: March 2009

Transient laminar forced convection of Newtonian fluids inside circular ducts and parallel‐plate channels subjected to stepwise variations of wall temperature is considered. Approximate analytical solutions are developed by making use of the generalized integral transform and the classical Laplace transform techniques. Higher order solutions are given for the case of a step change in wall temperature. A second‐order accurate finite‐difference solution is developed to assess the accuracy of the available approximate solutions. The Sign‐Count method is used to solve the resulting eigenvalue problems and determine as many eigenvalues and eigenfunctions as needed. Results are presented for the local Nusselt number, average fluid temperature and the wall heat flux over a wide range of the dimensionless axial coordinate.
Crystallization kinetics from transients of an MSMPR crystallizer
Authors: Tavare N. S.
Published: March 2009

Transient population density curves from a continuous MSMPR crystallizer obtained in response to an application of external non‐homogeneous forcing functions (like changes in feed concentration or flowrate) were used to deduce simultaneously nucleation and growth kinetics. Several simplified parameter estimation procedures were examined using simulated experimental observations of population densities and gave consistent results. Results however obtained from an experiment performed in a small continuous MSMPR crystallizer for the precipitation of calcium oxalate showed apparent scatter in all the algorithms. Methods using transient population density information by themselves may be useful to determine and also to provide an independent check on the reliability of kinetic parameter estimates.
A modified “inside‐out” algorithm for simulation of multistage multicomponent separation processes using the UNIFAC group‐contribution method
Authors: Saeger Roland B. , Bishnoi P. R.
Published: March 2009

A computational procedure using a modification of Boston and Sullivan's “inside‐out” multistage multicomponent separation algorithm (1974) is developed. In order to improve convergence behavior for problems involving mixtures with highly nonideal liquid phases, a two‐parameter model is used to describe liquid‐phase compositional effects upon the K‐factor. The quasi‐Newton methods of Mehra et al. (1983) and Nghiem (1983) are applied to solving various sets of solution variables in the proposed algorithm. Activity coefficients are calculated using the UNIQUAC activity‐coefficient model (1975) with parameters obtained from the UNIFAC group‐contribution method (1975). The computational procedure is applicable to distillation, absorption and reboiled‐absorption configurations. The proposed algorithm was implemented in a FORTRAN 77 program and tested on the Honeywell DPS 8/70M computer at the University of Calgary. Inclusion of the liquid‐phase model resulted in improved convergence behavior for nonideal systems in which the original “inside‐out” method failed to converge.
Effect of drop size and physical properties on dispersion height in the separating section of a liquid/liquid extraction column
Authors: Dalingaros W. , Hartland S.
Published: March 2009

The height of the dispersion formed in the separating section of an extraction column is given by

H = K/g (σ/Δρg)1/2 I/ϕo (Qd/A)2

Since calm conditions prevail the height of the sedimentation zone can be neglected and the dispersion is essentially dense‐packed. The effect of physical properties was investigated in a spray column using nine different liquid/liquid systems. A distributor divided into seven equal sectors enabled the effect of drop size and dispersed phase flow rate to be independently investigated.
Kinetics and reaction mechanism of hydrogen sulfide oxidation over activated carbon in the temperature range of 125–200°c
Authors: Ghosh Tushar K. , Tollefson Eric L.
Published: March 2009

The kinetics and reaction mechanism of the oxidation of hydrogen sulfide over activated carbon were studied in the temperature range 125–200°C. The heats of adsorption of oxygen and H2S were found to be 73.8 and 16.0 kJ/mol, respectively, in the above temperature range. The sorption constants and the reaction constant have been expressed as a function of temperature. The role of water in the oxidation reaction has been clarified. No evidence was found to show that sulfur catalyzes the oxidation reaction.
Velocity profiles at the exit of circular tubes
Authors: Leung S. K.‐L. , Esmail M. N.
Published: March 2009

An investigation has been carried out on velocity profiles of Newtonian liquids at the exit of circular tubes for Reynolds numbers from about 50 to 1000. A simple expression which asymptotically approaches a Poiseuille parabolic distribution for higher Reynolds numbers is obtained. Experimental measurements of extrudate swell ratios were used as criteria for convergence to the solution. Comparison with jet shapes from previous experimental and theoretical studies supports the obtained results. The work also illustrates a straightforward method for simplifying and solving the governing equations for laminar flows of thin liquid layers.
High shear jet‐mixers as two‐phase reactors: An application to the oxidation of phenol in aqueous media
Authors: Jaulin L. , Chornet E.
Published: March 2009

Jet‐mixers are known as devices capable of greatly enhancing the gas‐liquid interfacial areas. Their application to chemical reactions is discussed in this paper. The oxidation of phenols in aqueous media is considered.

Rates of oxidation fifty times higher than those previously observed can be achieved through a jet‐mixer discharging a fine mist into the reactor side operating at plug flow regime. The presence of hydrogen peroxide accelerates the oxidation. Kinetic information is provided.
On interpreting ft product distribution data
Authors: Rice N. M. , Wojciechowski B. W.
Published: March 2009

It is shown that a CSTR is essential for the correct evaluation of kinetic parameters in the Fischer‐Tropsch (FT) synthesis. Furthermore, a rather complicated expression is required in order to extract the correct growth probability at low carbon number in cases where a “break” is observed in the Anderson‐Schulz‐Flory (ASF) distribution.

It is shown that if product molecules can readsorb and continue to grow on a variety of locations where competing processes occur, the linearities of the ASF plot are preserved but the slopes of the plot no longer have a simple interpretation in terms of processes governing chain growth on the surface.

Finally, results obtained using an integral Plug Flow Reactor (PFR) are shown to yield “growth probabilities” which have no fundamental significance and are a function of the level of conversion and of the input H2/CO ratio.
Coal slurry fuel technology
Authors: Papachristodoulou G. , Trass O.
Published: March 2009

Volatile oil markets experienced in the seventies have promoted renewed interest in coal‐based fuel technologies. Coal‐slurry fuels have emerged as viable technical alternatives for oil and gas in utility and industrial boilers. Despite current low prices and the abundance of oil, concerns over its long‐term availability and price, as well as strategic considerations, make coal‐slurry technology attractive. Initially, coal‐slurry fuels were based on coal‐oil mixtures, now the emphasis is largely on coal‐water fuels.

This review assesses the status of the relevant technology. It covers the preparation of coal‐slurry fuels, slurry properties, combustion characteristics, emissions, current applications and concludes with their future outlook.
A correlation for hydrogen solubility in alicyclic and aromatic solvents
Authors: Shaw J. M.
Published: March 2009

A correlation for hydrogen solubility in aromatic, alicyclic, and heterocyclic hydrocarbon solvents is presented. This correlation, employing corresponding state theory, provides reliable estimates for hydrogen solubility, in simple and multicomponent solvents, over the temperature interval 0.45 ≤ Tr ≤ 0.97, and for pressures from 0.1 to 30.0 MPa. The correlation was found to have an average absolute error of 5.9% for 14 simple solvents, and 6.8% for 11 multicomponent solvents which include coal liquids and bitumen. Solvent specific coefficients are not employed, and the correlation is well suited for predicting hydrogen solubility in multicomponent ill defned solvents, or in simple solvents where experimental data are unavailable.
New analysis of non‐newtonian turbulent flowndashyield‐power‐law fluids
Authors: Thomas A. D. , Wilson K. C.
Published: March 2009

The writers' new analysis of non‐Newtonian turbulent flow is extended to the yield‐power‐law model. As the value of the exponent of the yield‐power law decreases from unity, the calculated friction factor begins by converging toward the Newtonian line at high velocity, then parallels it, and finally diverges downward. This prediction agrees with previously unexplained experimental results.
Effect of circulation rate on mass transfer in a forming drop
Authors: Guha D. K. , Vyarawalla F. , De P.
Published: March 2009

The prediction of mass transfer rate in an internally circulating drop forming in a continuous gaseous medium depends upon the residence time of a liquid element on the drop surface. A theoretical analysis has been made for the estimation of this contact time. The experimental results on comparison with the model show that the mass transfer rate is inversely proportional to the square‐root of the contact time as conceived by a modified penetration theory.
Film and penetration theories for a first‐order reaction in exothermic gas absorption
Authors: Chatterjee Siddharth G. , Altwicker Elmar R.
Published: March 2009

Film and penetration models for simultaneous heat and mass transfer are developed for the absorption of gas with a first‐order chemical reaction in the liquid phase with temperature‐dependent solubility and reaction rate coefficient. These two models represent two extreme conditions of interfacial temperature rise and gas solubility and they are compared with some previous models (Allan and Mann, 1979; Asai et al., 1985). The approximate analytical expressions of the penetration model of Asai et al. (1985) are in good agreement with the numerical results of this work. The results reveal that under many practical circumstances the gas‐liquid interfacial temperature may be several degrees Kelvin higher than the bulk liquid temperature. The degree of deviation of the enhancement factor from its isothermal value at the bulk liquid temperature depends on the degree of difference of a certain dimensionless activation energy group from zero, which confirms the previous finding of Asai et al. (1985).
Gas‐bubble hold‐up and axial dispersion coefficient of emulsion phases in fluidized beds
Authors: Kawase Y. , Moo‐Young M.
Published: March 2009

A model for liquid mixing in a gas‐liquid bubble column is extended to predict gas‐bubble hold‐up and axial dispersion coefficient of emulsion phases in fluidized beds. Reasonable agreement is found between the proposed model which includes no adjustable parameter and the available experimental data and correlations.
Predicting collection efficiency of separation cyclones: A momentum analysis
Authors: Li P. M. , Lin S. , Vatistas G. H.
Published: March 2009

This paper uses a quantity of moment of momentum to combine various parameters interacting in a separation cyclone. Due to construction features and flow characteristics, the swirl flow in the cyclone is essentially frictionless and, hence, the incoming momentums of both the transporting fluid and suspended particles are conserved. Visualizing a 50%‐separation screen installed, and employing a stability‐radius theory, the momentums are expressed in terms of distributed masses in the cyclone. Further, in conjunction with the continuity equation, the collection efficiency is determined. The predicted value differs from the experimental one by about 6%.
On the particle terminal velocity in a gas‐liquid medium with liquid as the continuous phase
Authors: Jean Rong‐Her , Fan Liang‐Shih
Published: March 2009

A mechanistic model was developed to describe the terminal velocity of spherical particles in a gas‐liquid medium with liquid as the continuous phase. The model was established based on the momentum balance of a single particle taking into consideration the drag and buoyancy forces due to the liquid phase and the bubble‐wake and particle interaction. The bubble‐wake and particle interaction coefficient was shown to be a function of the particle properties only. A comparison of the particle terminal velocity between the model prediction and experimental data obtained in this study was also made over a wide range of particle size and gas velocity.
Overall effectiveness factor of heterogeneous‐homogeneous chain reactions with one limited species in a catalytic slurry reactor
Authors: Hwang Bing Joe , Chou Tse‐Chuan
Published: March 2009

The analysis of the overall effectiveness factor for the reaction system involving heterogeneous‐homogeneous chain reactions at low concentration of one species is studied. A more general theoretical analysis for estimating the overall effectiveness factor of reaction systems which can be a heterogeneous‐homogeneous chain reaction system at low concentration of one species in a slurry reactor is presented, incorporating all the transport parameters. The concepts of overall effectiveness factors for reactions have been extended from the traditional heterogeneous reaction system to the heterogeneous‐homogeneous chain reaction system. The effects of reaction mechanism and kinetic models on the overall effectiveness factor are also proposed. Comparisons of the overall effectiveness factor for a slurry reactor with or without considering the reaction mechanism are also obtained.
Vapor‐liquid equilibrium of the binary mixtures CnH2n + 1(OH) (n = 2,3,4) + Propyl Ethanoate and + Ethyl Propanoate
Authors: Ortega J. , Ocon J. , Pena J. A. , De Alfonso C. , Paz‐Andrade M. I. , Fernandez J.
Published: March 2009

The compositions of the vapor‐liquid equilibria have been obtained in a small‐capacity recirculating still for the binary systems comprised of ethanol, propan‐l‐ol and butan‐l‐ol with propyl ethanoate and ethyl propanoate at a constant pressure of 101.32 ± 0.07 kPa. The experimental data were correlated with suitable equations and the azeotropes and their minimum boiling temperatures found were: ethanol + propyl ethanoate (x = y = 0.923; T = 351.5 K), propan‐l‐ol + propyl ethanoate (x = y = 0.610; T = 361.7 K), ethanol + ethyl propanoate (x = y = 0.875; T = 350.9 K) and propan‐l‐ol + ethyl propanoate (x = y = 0.534; T = 366.2 K).
Mass transfer at erosion‐corrosion roughened surfaces
Authors: Postlethwaite J. , Lotz U.
Published: March 2009

Rates of pipewall oxygen mass transfer in a 39 mm ID vertical pipe carrying an aqueous slurry containing 20 vol% 30‐50 mesh sand have been determined electrochemically with twin in‐line flow cells, one containing a mild steel specimen previously roughened by erosion‐corrosion and the other a smooth specimen. Measurements were also made without the solids present.

The three‐dimensional rough surface, with roughness height approximately 0.2 mm, and pitch/height in the range 5 to 10, resulted in mass transfer enhancement up to 100%, in both the slurry and the solution, with the maximum effect occurring at the dimensionless roughness height e+ ≈︁ 30.
Liquefaction of lignocellulosics in model solvents: Creosote oil and ethylene glycol
Authors: Vanasse C. , Chornet E. , Overend R. P.
Published: March 2009

The UDES‐S liquefaction process treats concentrated pastes (20% of initially present solids) of finely divided (dp < 0.5 mm) lignocellulosics in organo‐solvolytic media by means of thermo‐mechanical action in homogenizing valves.

The work described in this paper was carried out with Populus Deltoides in a process development unit capable of processing up to 4 kg of dry wood per hour. The model solvents used were creosote oil and ethylene glycol, which represent solvents that could be derived from the process or its products. Liquefaction mechanisms depend upon the solvent‐substrate interaction: with creosote oil, pyrolysis mechanisms predominate and lead to integral liquefaction of the wood while with ethylene glycol only fractional liquefaction was possible, apparently as a result of a complex formation between ethylene glycol and cellulose which protects the chain polymeric from being solubilized.