bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intravenous Administration of Low Molecular Weight and Unfractionated Heparin Elicits a Rapid Increase in Serum Pregnancy-Associated Plasma Protein A
Authors: Tertti Risto , Wittfooth Saara , Porela Pekka , Airaksinen K E , Metsärinne Kaj , Pettersson Kim 
Published: March 2009

Abstract
Background: Pregnancy-associated plasma protein A (PAPP-A) has been suggested as a useful diagnostic and prognostic marker in acute coronary syndromes. Because low molecular weight heparin (LMWH) and unfractionated heparin (UFH) are commonly used in these cases, we analyzed the effects of intravenous administration of these heparins on serum PAPP-A concentrations.
Methods: Serum concentrations of total and free PAPP-A were analyzed in 14 patients on chronic hemodialysis and in 10 coronary angiography patients. Ten of the dialysis patients received standard LMWH anticoagulation at the start of dialysis, and 4 were treated with a heparin-free method. Two of the patients on heparin-free hemodialysis received a reduced LMWH bolus 2 h after the start of dialysis. All angiography patients received UFH at the start of the procedure, and 1 patient received 2 extra boluses of UFH. Serum PAPP-A concentrations were analyzed before and during the dialysis session and during the coronary angiography examination.
Results: A rapid increase in total PAPP-A (median, 25-fold) was seen in all patients within 5 min of administration for both LMWH and UFH boluses. This response was due to an increase in free PAPP-A in the serum. PAPP-A did not increase significantly in the patients who underwent heparin-free hemodialysis. Repeated heparin boluses induced a new PAPP-A release. In vitro addition of heparins to samples of whole blood did not increase PAPP-A concentrations.
Conclusions: Intravenous administration of heparin induces an intense and rapid increase in free PAPP-A in the serum. We recommend that this effect be considered when PAPP-A is assessed as a biomarker in acute coronary syndromes.
Urinary Excretion of Buprenorphine, Norbuprenorphine, Buprenorphine-Glucuronide, and Norbuprenorphine-Glucuronide in Pregnant Women Receiving Buprenorphine Maintenance Treatment
Authors: Kacinko Sherri L , Jones Hendree E , Johnson Rolley E , Choo Robin E , Concheiro-Guisan Marta , Huestis Marilyn A 
Published: March 2009

AbstractBackground: Buprenorphine (BUP) is under investigation as a medication therapy for opioid-dependent pregnant women. We investigated BUP and metabolite disposition in urine from women maintained on BUP during the second and third trimesters of pregnancy and postpartum.Methods: We measured BUP, norbuprenorphine (NBUP), buprenorphine glucuronide (BUP-Gluc), and NBUP-Gluc concentrations in 515 urine specimens collected thrice weekly from 9 women during pregnancy and postpartum. Specimens were analyzed using a fully validated liquid chromatography-mass spectrometry method with limits of quantification of 5 μg/L for BUP and BUP-Gluc and 25 μg/L for NBUP and its conjugated metabolite. We examined ratios of metabolites across trimesters and postpartum to identify possible changes in metabolism during pregnancy.Results: NBUP-Gluc was the primary metabolite identified in urine and exceeded BUP-Gluc concentrations in 99% of specimens. Whereas BUP-Gluc was identified in more specimens than NBUP, NBUP exceeded BUP-Gluc concentrations in 77.9% of specimens that contained both analytes. Among all participants, the mean BUP-Gluc:NBUP-Gluc ratio was significantly higher in the second trimester compared to the third trimester, and there were significant intrasubject differences between trimesters in 71% of participants. In 3 women, the percent daily dose excreted was higher during pregnancy than postpregnancy, consistent with other data indicating increased renal elimination of drugs during pregnancy.Conclusions: These data are the first to evaluate urinary disposition of BUP and metabolites in a cohort of pregnant women. Variable BUP excretion during pregnancy may indicate metabolic changes requiring dose adjustment during later stages of gestation. .
Basic equations of mass transfer through biocatalytic membrane layer
Authors: Nagy Endre 
Published: March 2009

AbstractThe diffusive and convective mass transport through biocatalytic membrane layer (membrane bioreactor), without and with biochemical reactions, have been investigated. Similarly to the two‐film theory for gas‐liquid system with diffusive mass transport, only, mass transfer rates have been developed for the biocatalytic membrane layer and for the concentration boundary layer on the feed side of the membrane. Overall mass transfer coefficient has also been defined involving the two‐layer, simultaneous mass transfer, namely the mass transfer through the concentration boundary layer and biocatalytic membrane layer. The effect of the convective velocity (Pe number) and the biochemical reaction rate, namely first‐order and zero‐order reactions as limiting cases of the Monod kinetics, are demonstrated on the mass transfer coefficients accompanied by chemical reaction and on the concentration profiles. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Möglichkeiten zur Energierückgewinnung aus Wasserstoff bei der Chlor‐Alkali‐Elektrolyse
Authors: Moussallem I. , Pinnow S. , Turek T. 
Published: March 2009

AbstractWasserstoff entsteht als Koppelprodukt bei der Chlor‐Alkali‐Elektrolyse und wird, sofern eine Verwendung für chemische Synthesen nicht möglich ist, in der Regel thermisch durch Verbrennung in Feuerungsanlagen genutzt. Im vorliegenden Beitrag werden alternative Möglichkeiten zur Energierückgewinnung aus Wasserstoff energetisch und wirtschaftlich bewertet. Dabei zeigt sich, dass die Vermeidung der Entstehung von Wasserstoff mit Hilfe von so genannten Sauerstoffverzehrkathoden energetisch und wirtschaftlich vorteilhaft ist. Dies gilt insbesondere bei zukünftig weiter steigenden Strompreisen. Demgegenüber ist die Verstromung von Wasserstoff in Brennstoffzellen wegen des geringeren Wirkungsgrads erst dann ähnlich attraktiv, wenn sich die Kosten für Brennstoffzellen‐Systeme im Zuge einer zukünftigen Massenfertigung signifikant verringern lassen.
Mixing between a round jet and a transverse turbulent pipe flow
Authors: Rathgeber D. E. , Becker H. A. 
Published: March 2009

AbstractA light‐scatter technique, marker nephelometry, was used to obtain air‐in‐air mixing data on the system resulting from the injection, at right angles through a port in the wall, of a round subsonic jet into a fully developed turbulent pipe flow. Though the pipe Reynolds number was also varied, the important input variables were the port to pipe mean speed ratio of the input streams (2.5–12.5), and the port to pipe diameter ratio (0.020–0.058). Jet trajectories were measured and the associated mixing field was characterized in terms of both the jet source fluid mean concentration and concentration fluctuations. The process was also studied as to concentration fluctuation spectral density, integral scale, and intermittency.
Redox kinetics of benzene oxidation to maleic anhydride
Authors: Cordova Victor Rangel , Gau Georges 
Published: March 2009

AbstractSteady state kinetics of the oxidation reaction have been determined with the help of a gradientless semi‐differential, fixed‐bed reactor. The Mars and van Krevelen phenomenological model satisfactorily correlates the experimental data but a modification of the Langmuir‐Hinshelwood model taking into account partial coverage of the catalyst surface with reaction intermediates is preferred.Transient kinetics have been studied with a new automated periodic‐pulse reactor, directly connected to a gas chromatograph. The response of a catalyst (essentially V2O5–MoO3) to reduction and oxidation has been investigated. The rate of bulk (lattice) oxygen utilization as well as the degree of carbon coverage are estimated by this technique. Selectivity is dependent on the oxidation state of the catalyst: high partial pressure of either benzene or oxyen and high temperatures are detrimental to selectivity.
Pressure distribution in spout‐fluid bed reactors
Authors: Heil C. , Tels M. 
Published: March 2009

AbstractThe occurrence of several flow regimes in spout‐fluid beds was investigated. Four different flow regimes, viz. a packed bed flow regime, a bubbling and a fluctuating spouted bed flow regime and a stable spouted bed flow regime, were found to exist. Pressure distributions in a spout‐fluid bed were measured in several of these flow regimes by means of a moveable pressure probe. A theoretical model that describes the flow pattern in spout‐fluid beds was developed from fundamental relationships that govern the flow of gases through porous media. Pressure distributions calculated from this model agree fairly well with measured values.
Spouting with a porous draft‐tube
Authors: Claflin J. K. , Fane A. G. 
Published: March 2009

AbstractParticle motion and gas distribution have been measured in 0.3 m spouted beds with porous and solid wall draft‐tubes. Particle velocity in the annulus varied with gas rate and bed geometry. Narrow particle residence time distributions were observed under all conditions. Annular gas flow with the porous tubes exhibited a characteristic maximum in the lower part of the bed. A computer model has successfully simulated this phenomenon. The porous tube had a higher annular airflow than the solid tube at low separation distances, and a lower pressure drop for a given annular flow. A composite porous and solid wall tube offers improved performance.
Gas jets in fluidized beds and spouts: A comparison of experimental behavior and models
Authors: Filla M. , Massimilla L. , Vaccaro S. 
Published: March 2009

AbstractExperimental data reviewed include pressure profiles, gas and solids axial and radial velocity profiles, and solids concentration in the jet and spout. Similarities and differences from experimental evidence available for spouts in spouted beds and jets in fluidized beds are discussed. Modelling procedures are compared.
Visual observations of spouted bed gas combustion modes and their flow regimes
Authors: Khoe G. K. , Weve D. 
Published: March 2009

AbstractA study of a spouted bed combustion through direct visual observation in a half cylindrical bed (9 cm ID x 50 cm height, flat based) is reported. The different combustion modes are described as a function of the massflow of the gas mixture entering the bed and of the ratio of air to combustible. These combustion modes have been analyzed and documented with the aid of colour cinematography and photography. Bed temperatures have also been registered. Various bed heights of sand and different sizes of the orifice have been used.
Hydrodynamics and mass transfer characteristics of co‐current downflow packed tube columns
Authors: Patil V. K. , Sharma M. M. 
Published: March 2009

AbstractHydrodynamics and effective interfacial area in a 25 mm i.d. packed tube column were studied over a wide range of operating conditions for demister pad packings (DPP). Flow maps have been prepared. Values of effective interfacial area as high as 1880 m−1 in the spray flow regime were obtained. Data on pressure drop and effective interfacial area have been correlated for different flow regimes. Values of liquid side volumetric mass transfer coefficient, kL a, were measured by absorption and desorption of oxygen in different packed tube columns containing Pall rings (standard and low height to dia. ratio), multifilament wire gauge packings (MFWGP) and DPP. kL a was found to vary from 0.017 to 0.34 s−1 for DPP.Values of wall side solid‐liquid mass transfer coefficient, kSL, were obtained in a 25 mm i.d. copper tube column packed with MFWGP by the dissolution of copper in acidic dichromate solutions. Values of wall side heat transfer coefficient could be obtained by analogy.
Mass transfer characteristics of low H/D bubble columns
Authors: Gopal J. S. , Sharma M. M. 
Published: March 2009

AbstractThe mass transfer characteristics of 0.2, 0.6 and 1.0 m diameter bubble columns having a low height to diameter ratio (0.6 < H/D < 4) and operated at low superficial gas velocities (0.01 < VG < 0.08 m/s) were investigated. Different types of spargers were used to study their effect on the column performance.The values of effective interfacial area, a, and volumetric mass transfer coefficient, kLa, were measured by using chemical methods. The values of a and kLa were found to vary from 40 to 420 m2/m3 of clear liquid volume and from 0.01 to 0.16 s−1, respectively, in the range of VG, and VL covered in this investigation. The value of the liquid‐side mass transfer coefficient, kL, was found to vary from 3 × 10−4 to 7 × 104 m/s. The effect of the physical properties of the system on the values of a was also investigated. The height to diameter ratio and the column diameter did not have significant effect on the values of gas holdup, a and kLa. It was found that the sparger design is not of critical importance, provided multipoint/multiorifice gas spargers are used.The comparative performance of bubble columns having low H/D with horizontal sparged contactors and tall bubble columns has been considered.
A method for determining the settling behavior of dense suspensions
Authors: Al Taweel A. M. , Farag H. A. , Fadaly O. , Mackay G. D. M. 
Published: March 2009

AbstractAn accelerated method for evaluating the compaction behavior of dense suspensions is presented, in which centrifugal force is used to enhance settling rates and a highly‐compensated compound pendulum is used to detect the resultant small shifts in centre of gravity.The results obtained by following the temporal variation in suspension characteristics indicate that a Richardson and Zaki type of equation can describe the subsidence of very concentrated suspensions. The exponent n, and the ultimate sediment compaction density were found to be strongly influenced by small changes in the physicochemical characteristics of the suspended solids.
The effect of air distribution on the induced air flotation of fine oil in water emulsions
Authors: Van Ham Niel J. M. , Behie Leo A. , Svrcek William Y. 
Published: March 2009

AbstractThe induced air flotation (IAF) of a highly stabilized oil in water (o/w) emulsion has been studied experimentally in a batch column 10 cm in diameter and 150 cm in height. Column performance was strongly affected by the method of air distribution. The main variables investigated were the type of air distributor (either porous plate, single hole plate, or multi‐hole plate), initial oil concentraton (30‐600 mg/L), oil drop size distribution of feed (1.0‐30 μm), surfactant type, and gas superficial velocity. Results were successfully analyzed in terms of a first order kinetic rate model which yielded a removal rate constant (K1) that varied from 2.0 to 60.0 h−1. Corresponding total organic carbon (TOC) removal efficiencies went from 20 to 99.9 percent, illustrating the wide performance range for the flotation cell.
Low temperature oxidation of athabasca bitumen
Authors: Babu D. Ram , Cormack Donald E. 
Published: March 2009

AbstractThe kinetics of low temperature oxidation in the Athabasca oil sands were investigated over the temperature range 373 K to 459 K. Oxidation experiments, in which the sand‐free bitumen was vigorously stirred to obtain a homogeneous oxygen concentration throughout the bitumen, were carried out. It was concluded that the oxidation reaction is governed by three different kinetic expressions depending on temperature and past oxidation history. These are: (i) a high rate first order regime which is obeyed at low extents of oxidation and at temperatures below approximately 423 K; (ii) a second order regime, obeyed at low extents of oxidation and at temperatures greater than 423 K; and (iii) a low rate first order regime, obeyed for extents of oxidation greater than 1.7 moles O2/kg bitumen over the entire temperature range investigated.The partial molar enthalpy of low temperature oxidation was also evaluated, and was found to be constant over the range of oxidation extents studied.
Model experiments on sliding friction for application in hydraulic conveying of solids
Authors: Briscoe B. J. , Radwan H. , Streat M. 
Published: March 2009

AbstractThis paper describes a preliminary experimental study of the sliding friction of sand‐water mixtures when continuously propelled over glass surfaces by a potential energy gradient. The particle contact density at the glass wall and the work dissipated are estimated. These experiments are compared with the process of hydraulic conveying of sand‐water mixtures under a hydraulic gradient. It is argued that there is a unique correlation between the surface particle density and the frictional work irrespective of the nature of the driving force. This argument allows a realistic estimate of the frictional work in hydraulic conveying to be made from the measurement of surface particle velocity during flow. In an example cited, the dynamic coefficient of sliding fraction for a particular case of sand‐water flow is found to be a function of mean velocity and decreases from about 0.65 to 0.22 for velocities of 0.47 and 1.07 m/s respectively.
The effect of moisture on the rheology of brown coal‐oil suspensions
Authors: Low G. S. , Bhattacharya S. N. 
Published: March 2009

AbstractThe rheological properties of brown coal‐oil suspensions were investigated using both a Contraves rheometer and a Weissenberg rheogoniometer. The aging characteristic of the suspensions was found to be due to the moisture in the coal and the presence of large numbers of micropores. Moisture in the suspension caused aggregation of coal particles and diffusion of oil in the pores was responsible for the reduction in the volume fraction of free carrier oil. Both the yield stress and apparent viscosity were found to increase sharply if the coal contained more than 10 wt% moisture. Photomicrographs were also used to identify the cause of aggregation in brown coal‐oil suspensions.
Oxygen enrichment in rotary lime kilns
Authors: Watkinson A. P. , Brimacombe J. K. 
Published: March 2009

AbstractThe operation of a pilot‐scale rotary lime kiln, fired with natural gas, was studied to determine the effects of enriching the combustion air with oxygen. The variables of interest were the temperature, calcination and heat flow patterns within the kiln as functions of the fuel rate, oxgyen concentration and limestone feed rate. All tests were conducted with essentially a stoichiometric fuel/oxygen ratio and employed two different limestones. Data are presented to show the increase in kiln throughput that can be achieved using oxygen enrichment. The results are interpreted using detailed measurements of axial solids, gas and wall temperatures and axial calcination profiles. These permit the evaluation of the driving forces for the various heat exchange processes, and of local heat flow to the solids bed.
Optimal control of a continuous two valves in series letdown flow system
Authors: Oǧuztöreli M. Namik , Özüm Baki 
Published: March 2009

AbstractIn the present work, the dynamics of two interacting valves‐in‐series letdown flow system subjected to the optimal control of the liquid levels in two vessels and of simultaneous distribution of the total pressure drop amongst the valves has been studied. The controllers of the process (the valve constants) have been obtained as functions of the input and output liquid volumetric flow rates and process characteristics, assuming no time‐lags in the measurement of the state variables and of the controllers' actions.
Penetration theory solution for gas absorption and chemical reaction in cocurrent and countercurrent flow wetted‐wall columns
Authors: Datta Ravindra , Rinker Robert G. 
Published: March 2009

AbstractPenetration theory solutions are provided for gas absorption with or without a (pseudo) first‐order irreversible chemical reaction in cocurrent and countercurrent flow wetted‐wall columns, taking into account a constant gas‐film resistance as well as the axial decrease in gas composition due to absorption, while assuming non‐rippling laminar flow for the liquid phase and plug flow for the gas phase. Limiting solutions are also obtained for situations when either the gas phase resistance or the axial variation of gas composition is negligible. The results are suitable for ϕ ≥ 3 and can be used for both Newtonian and non‐Newtonian liquids.
Measurement, correlation and prediction of binary vapor‐liquid equilibria for alcohol‐tetrachloroethene systems
Authors: Venkateswara Rao K. , Ravi Prasad A. 
Published: March 2009

AbstractExperimental isobaric vapor‐liquid equilibria of binary mixtures of tetrachloroethene with ethanol, 2‐propanol, 2‐butanol and 2‐pentanol have been measured at 101.08 kPa. The UNIFAC (Fredenslund et al., 1975), a group contribution model and the activity coefficient models of Margules and Van Laar (as presented by Carlson and Colburn, 1942), Wilson (1964), NRTL (Renon and Prausnitz, 1968) and UNIQUAC (Abrams and Prausnitz, 1975) have been used to predict the vapor composition from measured T‐x data of ten binary mixtures of alcohol‐tetrachloroethene including these four systems. The average absolute deviation between the experimental and the predicted vapor composition with the UNIFAC model ranges from 0.006 to 0.023 mole fraction and that with the activity coefficient models ranges from 0.003 to 0.038. The maximum deviation in both the cases occurred in the data of 1‐propanol (Venkateswara Rao et al., 1980).
Particle—gas dispersion effects in a round jet
Authors: Subramanian Viswanath , Ganesh Raman 
Published: March 2009

AbstractThe fully developed region for a two‐phase jet exhibits similarity for velocity and concentration. A power law expression approximates the velocity distribution and the square root of this profile coincides with the concentration distribution. Measurements show that particle dispersion decreases with increase in particle concentration and the gas mixing rate is lower than the particle mixing rate. The turbulent Schmidt Number remains constant at a value equal to 0.47.
Sectionalised bubble column: Gas hold‐up and wall side solid—Liquid mass transfer coefficient
Authors: Patil V. K. , Joshi J. B. , Sharma M. M. 
Published: March 2009

AbstractThe effect of gas sparger type, clear liquid height, liquid viscosity and addition of electrolyte on fractional gas hold‐up in a 0.38 m i.d. sectionalised bubble column (SBC) was studied for superficial gas velocities ranging from 0.03 to 0.15 m s−1. A study of the wall side solid–liquid mass transfer coefficient, kSL, has been made by considering the dissolution of copper in acidic dichromate solutions. The variation of kSL with axial distance in a section for different gas velocities has been explained. A comparison between the performance of sectionalised bubble columns and conventional bubble columns has been presented. In some cases, the SBC may prove to be superior to bubble columns in practice.
Influence of forced cycling on the fischer‐tropsch synthesis. Part I. Response to feed concentration step‐changes
Authors: Feimer J. L. , Silveston P. L. , Hudgins R. R. 
Published: March 2009

AbstractThe response of the Fisher‐Tropsch synthesis to composition step‐change was studied as part of a larger study on the influence of forced feed composition cycling on the product distribution from this synthesis reaction. Using a promoted iron catalyst, studies were conducted at 384 kPa total pressure in a fixed‐bed differential reactor held at 246°C by means of an oil bath. It was determined that the reaction rate was not influenced by mass or heat transfer effects.The maxima in the curves of steady state rate versus feed composition for various products occurred considerably above the stoichiometric ratio for each product olefin. This fact suggested that the rate was probably controlled by hydrogen adsorption in the initiation sequence. Support for this interpretation was also found from the response of the rates of production of light hydrocarbons (C2 to C5) to the step‐changes in feed concentration.