bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient heating and cooling of cocurrent three‐phase fluidized beds
Authors: Grandjean B. P. A. , Carreau P. J. , Paris J.
Published: March 2009

The thermal transient behaviour of three‐phase fluidized beds have been investigated for a liquid viscosity ranging from 35 to 75 mPa · s. For the operating conditions used in this study, a 6 mm glass particle bed was found to have a thermal response similar to that of a fixed bed. The transient responses, which were not significantly affected by gas sparging, were, however, faster for heating than for cooling. This result has been analyzed from a model assuming liquid plug flow through stationary particles using combined free and forced convection correlations for heat transfer around the particles. Different correlations are then proposed to predict the contribution of natural convection to the liquid‐to‐particle heat transfer in heating and cooling modes. The effect of gas sparging was found to strongly affect The 2.0 mm particle bed responses but only moderately the 3.9 mm bed responses. These responses were analyzed using axial dispersion models for the liquid and solid phases. For the 3.9 mm particle bed, the axial dispersion coefficient of the solids, EZS, was found to be of the same order of magnitude as that of the liquid coefficient, EZL. However, the value of Ezs for the 2 mm particle bed was found to be five times that of EZL.
Pool boiling heat transfer to saturated water and refrigerant 113
Authors: Jamialahmadi M. , Blöuchl R. , Müuller‐Steinhagen H.
Published: March 2009

Pool boiling heat transfer coefficients were measured for saturated water at atmospheric pressure and for saturated refrigerant Rl13 at 102 kPa and 341 kPa. The measured heat transfer coefficients were compared with values found by other researchers and with the predictions of correlations from the literature. Bubble departure diameter, bubble frequency and nucleation site density were recorded for each experiment. A pool boiling model recently developed by Blöchl and Bier is described and limitations of the model are discussed.
Kinetics of aromatics hydrogenation of bitumen‐derived gas oils
Authors: Yui Sok M. , Sanford Emerson C.
Published: March 2009

Using pilot scale trickle‐bed reactors with commercial NiMo/Al2O3 catalysts, hydrotreating of five bitumen‐derived gas oils was conducted. Aromatic carbon was determined by l3C NMR spectra. A simple power law kinetic model of aromatics hydrogenation was developed, assuming a first order reversible reaction which accounts for both forward and reverse rate constants. The model includes power terms for space velocity and hydrogen partial pressure, and the ratio of naphthenes and aromatics in the feed. The model was tested with our experimental results and kinetic parameters were determined. Aromatic carbon calculated with these parameters is in good agreement with observed results.
Studies on hydrophilic polysulfone ultrafiltration membranes
Authors: Tremblay A. Y. , Tam C. M. , Guiver M. D. , Dal‐Cin M. M.
Published: March 2009

Ultrafiltration membranes were produced from carboxylated polysulfone polymers having different degrees of substitution (DS). Solute separation was found to increase with increasing DS. The techniques of single solute permeation and permoporometry were used to determine the pore size of these membranes. Permoporometry measurements indicated that pore size decreased with increasing DS. Solute separation was predicted by inserting the distribution of pore sizes obtained from permoporometry into a restricted transport model. Similar results were obtained from a nonlinear least squares fit of the restricted transport model to the experimental data. Both techniques produced similar sieving curves. It was concluded that pore size decreases were not due to the increasing repulsion of solute molecules by hydrophilic polysulfone but to changes in polymer solution properties as the DS increased.
Rheological properties of bitumen in water emulsions with added solids
Authors: Yan Yuhua , Pal Rajinder , Masliyan Jacob
Published: March 2009

Experimental work was carried out to investigate the rheological properties of bitumen in water emulsions containing solids of different shape and size. The bitumen volumetric concentration was varied up to 60%, solids free basis, and the solids volume fraction (total volume basis) was varied up to 0.2. Irregular‐shaped silica sand (average diameter: 9 and 33 μm) and smooth spherical glass beads (average diameter: 27 and 44 μm) were used as the added solids.

In the low shear stress range, shear thinning behavior was observed for bitumen in water emulsions. At high shear stress, the viscosity of the emulsions became fairly independent of the shear stress. The addition of solids to the bitumen emulsions increased the mixture viscosity. The addition of irregular‐shaped silica sand gave a higher viscosity than a similar addition of the spherical glass beads. The viscosity of the emulsion/solids mixtures was influenced by the solids size as well; the smaller size particles gave a higher viscosity.

The addition of solids to the bitumen emulsions also induced shear thickening (dilatancy) behavior at high solids volume fraction. The degree of the shear thickening increased with the oil concentration.
Réacteur électrochimique à lit granulaire transporté
Authors: Benzina M. , Lacoste G.
Published: March 2009

Ce travail présente l'étude d'un réacteur électrochimique à matrice solide granulaire lorsque celle‐ci est placée dans un tronc conique. La solution à traiter percole le lit granulaire du réacteur en écoulement du fait de la gravité tout en lui assurant une bonne cohésion et donc une conductivité électronique satisfaisante.

Les solutions numériques des équations différentielles liées aux bilans de masse et de charge permettent d'atteindre les distributions de concentration, de courant et de potentiel dans le cas où le lit granulaire est maintenu fixe. Une évolution de ces distributions expérimentales est discutée dans le cas où le lit granulaire est mis en mouvement.

L'évolution des concentrations (écoulement piston) et l'influence des débits liquide et solide discutés et illustrés dans le cas de la récupération de cuivre de solutions diluées (< 500 ppm) d'acide sulfurique. Un diagramme de dimensionnement pour chaque cas de percolation a finalement été proposé.
Thermolysis of glycol lignin in the presence of tetralin
Authors: Thring Ronald W. , Chornet Esteban , Overend Ralph P.
Published: March 2009

An organosolv (ethylene glycol) hardwood lignin has been thermally treated in the presence of tetralin, a hydrogen donor solvent. The effects of reaction temperature and time on product distribution were studied as a function of a seventy index, Xc = ℓn (Rω with Rω = Δt t × exp [(Tr ‐ Tb)/ω] where Δt = time, Tr = reaction temperature, Tb = base temperature, and ω = characteristic parameter. Under the conditions used, up to 60% of the lignin can be converted to liquid and gaseous products. Syringols, guaiacols, aromatic aldehydes and ketones predominate at low treatment severities whilst phenol, catechol and their methyl and ethyl derivatives are the main monomers at high severities. Comparison of our data with parallel works is shown to be effectively done through the severity index, Xc.
Fractionation of woodmeal by prehydrolysis and thermal organosolv. Process strategy, recovery of constituents, and solvent fractionation of lignins so produced
Authors: Thring Ronald W. , Chornet Esteban , Overend Ralph P.
Published: March 2009

A prototype hardwood Populus deltoids has been fractionated in kg quantities into its primary constitutive polymers, namely, cellulose, hemicelluloses, and lignin, under optimal recovery conditions for each fraction.

Our approach is targeted at processing sawdust or finally divided wood (dp ≤ 0.5 mm) and involves a thermomechano‐solvolytic treatment of medium consistency suspensions in two process development units operated sequentially. Firstly, the hemicellulose fraction is removed from the initial wood by a aqueous‐steam pretreatment (auto‐hydrolysis) at conditions where nearly 90% of the hemicelluloses are solubilized. Secondly, the treated wood (lignocellulose) is separated into cellulose and lignin rich fractions by subjecting it to an organosolvolytic treatment using ethylene glycol as solvent. An experimental unit which can be operated in semi‐continuous or continuous modes is described and was employed for this step. The recovery of each fraction via appropriate mass balances is presented.

Also, a comparative characterization of the lignins isolated via (a) the direct solvolysis route and (b) the sequential aqueous‐steam pretreatment followed by solvolysis approach is made using solvent fractionation, molar mass distribution, and 13C NMR spectroscopy methods.
Flow simulation of herschel‐bulkley fluids through extrusion dies
Authors: Mitsoulis E. , Abdali S. S. , Markatos N. C.
Published: March 2009

The flow of viscoplastic materials through extrusion dies has been studied numerically using the finite element method. Rheological data for viscoplastic doughs have been fitted by the Herschel‐Bulkley model, which incorporates a yield stress into the power‐law model. Non‐isothermal simulations show the extent and shape of yielded/unyielded regions and the development of temperature field assuming different modes of heat transfer at the boundaries. The results reveal that viscous dissipation causes appreciable temperature rises in the extrudate in agreement with measured values at the extruded material surface. The extrudate swell results show a maximum for a certain range of apparent shear rates also observed experimentally. However, the inelastic simulations based on the Herschel‐Bulkley model always under‐predict the experimental swelling values. A heuristic approach is also used to determine the level of elasticity required to produce the experimental values.
Water flow through helical coils in turbulent condition
Authors: Das Sudip Kumar
Published: March 2009

Experimental data on pressure drop across six helical coils made of rough transparent PVC pipes for flow of water in turbulent condition are presented. A correlation for predicting the friction factor has been developed.
The role of gas phase momentum in determining gas holdup and hydrodynamic flow regimes in bubble column operations
Authors: Reilly I. G. , Scott D. S. , Debruijn T. J.W , Macintyre D.
Published: March 2009

Experiments conducted in 0.15 m diameter bubble columns using water and non‐aqueous liquids have shown that the gas velocity at which transition from the bubbly flow to the churn‐turbulent flow regime occurs is a function of gas density. The transition velocity increased with increasing gas density. The direct effect of gas density on gas holdup in the bubbly flow regime is small with only a slight increase in holdup being observed at higher densities (ϵG α ρg 0.04). In the churnturbulent region a much greater effect of gas density on gas holdup was observed. These differences were found to be a direct function of the differences in holdup values at the transition points. Gas holdup was found to be a function of the gas phase momentum. In the bubbly flow regime holdup was directly proportional to momentum while in the churn‐turbulent regime holdup was proportional to momentum to the one third power.

Reasons for this behaviour are discussed, as well as the implied effects on liquid mixing in bubble column slurry reactors. The effects of gas density may offer an explanation for some apparently anomalous published results.
Wall effect on mixed convection from horizontal surfaces with a variable surface heat flux
Authors: Aldoss T. K. , Jarrah M. A. , Duwairi H. M.
Published: March 2009

This work investigates analytically the wall effect on the mixed convection from a horizontal plate embedded in porous media. Variable surface heat flux is assumed at the plate. The wall effect due to no‐slip boundary condition at the wall is introduced using the Brinkman model. Two sets of transformations are used, one for the forced convection dominating regime (FCDR) and the other one for the natural convection dominating regime (NCDR). The wall effect is found to be characterized by the boundary parameters L = DaxPex /ϵ in FCDR and by M = Dax Ra:/ϵ in NCDR. Velocity as well as temperature profiles are calculated at different values of governing parameters. Local Nusselt number variation for the entire mixed convection regime is also calculated and presented. Accurate correlations for local and average Nusselt number valid for the entire regime of mixed convection and for the range of boundary‐parameter from 0 to 100 are obtained.
Analysis of a ring‐shaped sensor for use in packed‐bed heat transfer studies
Authors: Giudici Reinaldo , Do Nascimento Cláudio AugustO Oller
Published: March 2009

A new type of ring‐shaped temperature sensor for packed‐bed heat transfer studies is presented. This ring‐shaped sensor is easy‐to‐build and allows one to filter the experimental angular temperature fluctuations. This device is more effective for beds of small tube‐to‐particle diameter ratio. The proposed device is able to eliminate the effect of the angular position on temperature measurements in packed beds. This sensor property is confirmed both experinientally and theoretically. For demonstration purpose, packed beds of six different materials were studied. Effective thermal radial parameters obtained using the ring‐shaped sensors have shown trends similar to published packed‐bed heat transfer data.
Reactivation of partially‐sulphated limestone particles from a cfb combustor by hydration
Authors: Couturier M. F. , Marquis D. L. , Steward F. R. , Volmerange Y.
Published: March 2009

Spent limestone samples from the bed and baghouse of a 22 MWe circulating fluidized bed (CFB) boiler were hydrated and then sulphated in a thermogravimetric analyzer under conditions similar to those found in CFB combustors (850°C, 0.3% SO2, 9% O2, 9% CO2 and 81.7% N2). Hydration using water gave faster rates and higher levels of conversion of the residual CaO to Ca (OH)2 than immersion in pure steam at 150 and 200°C. The particles expanded during hydration and their internal volume increased from 0.1 cm3/g Ca before hydration to nearly 0.6 cm3/g Ca after dehydration. Hydration rejuvenated the reactivity of the bed material but not that of the baghouse particles. The conversion of Ca to CaSO4, in the treated bed particles increased from 32% to over 80% during re‐sulphation.
Minimum spouting velocity in multiple spouted beds
Authors: Murthy D. V. R. , Singh P. N.
Published: March 2009

Studies have been carried out in multiple spouted beds having 2, 3 and 4 spout cells; different fluid inlet orifices and different solids have been used with air and water as spouting fluids. The minimum spouting velocities are measured for different bed depths. The experimental data for particle Reynolds number at minimum spouting have been correlated and the square root mean deviation between the calculated and experimental values is found to be 8.75 %.
Diffusion in liquid‐filled pores of activated carbon. I. Pore volume diffusion
Authors: Leyva‐Ramos R. , Geankoplis C. J.
Published: March 2009

The adsorption isotherms on activated carbon were measured for the following six systems: benzaldehyde, phenol, and potassium chloride in water; benzene, isopropylbenzene, and phenol in cyclohexane. The systems isopropylbenzene and benzene each in cyclohexane and potassium chloride in water proved to be slightly adsorbing systems, whereas the benzaldehyde and phenol each in water were highly adsorbing systems. The rate of diffusion of the slightly adsorbing solutes was interpreted by assuming that the intraparticle diffusion was due to pore volume diffusion. The results indicated that the tortuosity factor for activated carbon is 3.5. The effective pore volume diffusivity and the tortuosity factor were not affected by the concentration of the solute, solute molecular size and the particle diameter. The external mass transfer resistance was negligible when pore volume diffusion was the controlling intraparticle diffusion mechanism.
Characterization of robust performance using response surfaces
Authors: Krishnapura Venugopal G. , Jutan Arthur
Published: March 2009

Design of robust controllers in the face of process model uncertainty is an important problem. The new design methodologies in the frequency domain have sought to address some of the issues involved in robust control. Never‐theless, the characterization and measurement of uncertainty remains a somewhat difficult and abstract task. In order to easily compare and characterize robust performance of alternate stable control structures, it would be useful to have an intuitive, easily applicable measure of robust performance. In this paper we propose a new time domain based measure of robust performance using geometric concepts borrowed from Response Surface Methodology. The measure is used to characterize robust performance of single‐input‐single‐output systems. Simulations results are provided to illustrate the use and intuitive appeal of the new measure.
Cake filtration of suspensions in viscoelastic fluids
Authors: Kozicki W. , Kuang P. Q.
Published: March 2009

The fundamental framework for cake filtration of suspensions in viscoelastic media is extended to include the effects of polymer retention, including adsorption in the filter cake, polymer retention and elongational flow in the filter medium, which also undergoes compaction, and evaluation of polymer degradation in the filter cake and medium. Experimental data obtained in constant pressure filtration of starch suspensions in dilute aqueous polyacrylamide solutions confirmed the prediction of an enhanced apparent medium resistance Rma and a reduced cake resistance αR. Evaluations are presented of the contributions to the pressure drop due to enhanced normal stresses in elongational flow and to polymer retention (adsorption), and of the ratio of the particle size with and without adsorbed polymer in the cake. The analysis of the data points to high levels of polymer degradation during the flow of the polymer solution through the filter cake and medium.
The operating cost of electrocoagulation
Authors: Donini J. C. , Kan J. , Szynkarczuk J. , Hassan T. A. , Kar K. L.
Published: March 2009

The electrocoagulation of kaolinite and bentonite suspensions was studied in a pilot electrocoagulation system at the Western Research Center of CANMET to assess the operating cost and efficiency of the process. Factors affecting the operating cost such as, the formation of passivation layers on electrode plates, flow velocity and concentration of sodium chloride in the suspension were examined. The operating costs investigated in this paper were the power cost of the electrocoagulation cell and the material cost due to the consumption of the aluminum electrode. Comparison was based on the settling properties of the treated product: turbidity, settling rate, and cake height. Higher concentration of sodium chloride resulted in greater amount of aluminum dissolved chemically and electrochemically into the suspension and thus a better clarity of the supernatant of the treated product. Increased flow velocity could reduce significantly the operating cost while improving both clarity of the supernatant and the compactness of the sludge volume. The passivation layers developed quickly with time during the electrocoagulation process and more energy became wasted on the layers.
Kinetic of copper ion exchange onto iminodiacetic resin
Authors: Mijangos F. , Diaz M.
Published: March 2009

The internal porosity and swelling/shrinking of a chelating iminodiacetic type ion exchange resin have been experimentally studied during the uptake of copper onto it. The swelling of the particle could be analyzed with a modified model on th basis of the unreacted core model (UCM), including the influence of chemical equilibrium. The ion exchange kinetic results in batch experiments are used with the UCM to calculate the effect of pH on the internal diffusion coefficients. Results from shallow bed experiments with mixed internal and external diffusion controls have shown the applicability of the above model to analyze ion exchange with low external velocities.
Optimization of impeller design for gas inducing type mechanically agitated contactors
Authors: Mundale V. D. , Joshi J. B.
Published: March 2009

Rates of gas induction and fractional gas hold‐up were measured in a 0.57 m i.d. gas inducing type mechanically agitated contactor. Several designs of the impeller were employed for optimizing the rate of gas induction with respect to power consumption. The effect of blade width blade, angle, blade thickness, blade curvature, number of blades, etc. on gas induction, has been investigated in detail. An optimum design has been proposed. Hysteresis in the gas induction rate and power consumption was observed for a wider impeller projecting out of stator.
Retained properties of concrete exposed to high temperatures: Size effect
Authors: Arioz Omer
Published: March 2009

Concrete as a construction material is likely exposed to high temperatures during fire. The retained properties of concrete after such exposures are still of great importance in terms of the serviceability of structures. This paper presents the effects of high temperatures on the physical, mechanical, and microstructural properties of concrete. Specimens with different sizes were exposed to high temperatures ranging from 200 to 1200∘C. The compressive strength, splitting tensile strength, ultrasonic pulse velocity, and rebound numbers of the specimens were determined. The microstructures of the specimens were examined by scanning electron microscope (SEM) analyses. The test results indicated that the retained compressive strength of concrete considerably decreased with increase in temperature. The effect of specimen size on the retained compressive strength was not pronounced. The retained splitting tensile strength of concrete remarkably reduced as the temperature was increased. The specimen size played an important role on the retained splitting tensile strength of concrete up to 400∘C. The test results revealed that ultrasonic pulse velocity (UPV) test can be successfully used in order to check the uniformity of fire‐damaged structures. The rebound numbers decreased with increase in exposure temperature. SEM studies on specimens exposed to 800∘C revealed significant changes in the microstructure of the concrete. Copyright © 2009 John Wiley & Sons, Ltd.
Commentary on “A roadmap for the prevention of dementia II. Leon Thal Symposium 2008.” Innovations in care that advance Alzheimer's disease drug development
Authors: Foster Norman L. , Andersen Troy C. , Zamrini Edward Y.
Published: March 2009

Advancing the development of drugs for the prevention and treatment of Alzheimer's disease (AD) is dependent on the ability of investigators to identify, recruit, and retain appropriate subjects in clinical trials. Innovations in care that link primary‐care providers with AD researchers can help overcome barriers to early, specific diagnosis and access to research studies. Collaborative care provides a new paradigm for the mutual benefit of patients, providers, and AD research. Recommendations to achieve this goal include funding clinical centers of excellence in AD, linked with community physicians to utilize clinical care and initial evaluations as early entry points for patients into AD research, and funding mini‐fellowships for community physicians. Reimbursement for dementia care should be expanded to include periodic cognitive assessments for at‐risk individuals, medically directed dementia education, and diagnostic imaging and biomarkers. These innovations can simultaneously improve the translation of research advances, and benefit AD research.
Effect of incubation and rearing temperature on locomotor ability in barramundi, Lates calcarifer Bloch, 1790
Authors: Carey Geoff R. , Franklin Craig E.
Published: March 2009

Temperature profoundly influences virtually all aspects of fish biology. Barramundi, Lates calcarifer Bloch, 1790, is a catadromous fish that undergoes several migrations in its life cycle, necessitating locomotion under various thermal conditions. The present study examined the effects of varying thermal regimes on performance in juvenile L. calcarifer by determining the effects of rearing and ambient temperature on burst (Umax) and sustained (Ucrit) swimming ability. Fish were incubated at three set temperatures, 26°C (cool), 29°C (control) and 31°C (warm), from egg fertilisation until first feeding before some of the larvae were allocated to different temperatures to differentiate the effects of incubation temperature v. rearing temperature on subsequent swimming performance. Individuals incubated and reared at the cool (26°C) temperature showed significantly faster burst speeds at the 26°C test temperature than fish from any other treatment group. This indicates the ability of L. calcarifer to thermally acclimate burst swimming. However, there was no evidence that incubation temperature (as opposed to rearing temperature) affected burst or sustained swimming ability. Swimming ability was significantly affected by the test temperature, with the Umax of fish highest at the 29°C test temperature. Lower test temperatures depressed both burst and sustained swimming ability. Juvenile L. calcarifer can acclimate Umax, but swimming ability was unaffected by incubation thermal history.
A population study of a mutation allele associated with cone–rod dystrophy in the standard wire‐haired dachshund
Authors: Wiik A. C. , Thoresen S. I. , Wade C. , Lindblad‐Toh K. , Lingaas F.
Published: March 2009

Cone–rod dystrophy in the standard wire‐haired dachshund (SWHD) is inherited as a simple autosomal recessive trait and the recently discovered mutation is widespread within the SWHD population in Norway and other Scandinavian countries. The gene frequency was estimated to be 4.8%. On the basis of the assumption that the size of the ancestral haplotype around a mutation is inversely correlated with the number of generations since the mutation arose, we have found that the mutation is of a relatively recent origin. The conserved haplotype was found to be 8 Mb in size and therefore we estimate that the mutation arose roughly eight generations (approximately 37 years) ago. This indicates that the mutation arose after breed separation.
Haemodynamic characteristics of hypertension induced by prenatal cortisol exposure in sheep
Authors: Moritz Karen M , Dodic Miodrag , Jefferies Andrew J , Wintour E Marelyn , DeMatteo Robert , Singh Reetu R , Evans Roger G
Published: March 2009

1. Administration of glucocorticoids to ewes early in pregnancy results in offspring with hypertension in adulthood. The hypertension in female offspring exposed to dexamethasone is associated with increased cardiac output, but whether this is also true in cortisol‐exposed offspring is unknown.

2. Systemic haemodynamic variables were measured under basal conditions in castrated male and female adult sheep exposed to cortisol (5 mg/h) or saline (0.19 mL/h) from 26 to 28 days of gestation. To examine the contribution of the autonomic nervous system to maintenance of basal arterial pressure in established hypertension in cortisol‐exposed sheep, responses to adrenoceptor blockade (intravenous infusion of 0.15 mg/kg per h phentolamine plus 0.4 mg/kg per h propranolol) and ganglionic blockade (intravenous infusion of 125 mg/h hexamethonium) were examined in castrated male offspring.

3. Mean arterial pressure and calculated systemic vascular resistance were 9% and 17% greater, whereas cardiac output tended to be 8% less, in cortisol‐compared with saline‐exposed sheep. These effects were not sex dependent. The depressor response to ganglionic blockade and the initial phase of the depressor response to adrenoceptor blockade were greater in cortisol‐compared with saline‐exposed sheep.

4. These results indicate that hypertension in offspring exposed prenatally to cortisol is associated with increased total peripheral resistance, mimicking observations in human patients with chronic hypertension. Furthermore, the increased vascular resistance appears to be dependent, at least in part, on an increased effect of sympathetic vasomotor drive. Taken together with previous findings, the present observations suggest that prenatal cortisol and dexamethasone programme altered adult cardiovascular function via distinct mechanistic pathways.
Bone tissue responses to glass fiber‐reinforced composite implants – a histomorphometric study
Authors: Ballo A. M. , Akca E. A. , Ozen T. , Lassila L. , Vallittu P. K. , Närhi T. O.
Published: March 2009

Objectives: The aims of this study were to evaluate bone‐to‐implant contact (BIC) and the osteoconductive capacity of bioactive fiber‐reinforced composite implant (FRC) in vivo.

Material and methods: Threaded sand‐blasted FRC implants and threaded FRC implants with bioactive glass (BAG) were fabricated for the study. Titanium implants were used as a reference. Eighteen implants (diameter 4.1 mm, length 10 mm) were implanted in the tibia of six pigs using the press‐fit technique. The animals were sacrificed after 4 and 12 weeks. Histomorphometric and scanning electron microscopic (SEM) analyses were performed to characterize BIC.

Results: In general, the highest values of BIC were measured in FRC‐BAG implants, followed by FRC and Ti implants. At 4 weeks, the BIC was 33% for threaded FRC‐BAG, 27% for FRC and 19% for Ti. At 12 weeks, BIC was 47% for threaded FRC‐BAG, 40% for FRC and 42% for Ti. Four weeks after implantation, all the implants appeared biologically fixed by a newly formed woven bone arranged in the thin bone trabeculae filling the gap between the implant and the bone of the recipient site. Twelve weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the FRC‐BAG implants.

Conclusion: Our results suggest that the FRC implant is biocompatible in bone. The biological behavior of FRC was comparable to that of Ti after 4 and 12 weeks of implantation. Furthermore, the addition of BAG to the FRC implant increased peri‐implant osteogenesis and bone maturation.
Characteristic features of trabecular bone in edentulous mandibles
Authors: Ulm C. , Tepper G. , Blahout R. , Rausch‐Fan X. , Hienz S. , Matejka M.
Published: March 2009

Background: The density and architecture of the alveolar trabecular bone are crucial to the stability of an endosseous implant. A significantly higher implant failure rate can be expected when implants are placed in alveolar bone with reduced density and stability. Therefore, the present study aimed to describe the trabecular bone structure of edentulous mandibles.

Method: Two hundred and seventy‐eight bone sections, including the lateral incisor, first premolar, and first molar regions, were obtained from 128 edentulous lower jaws (68 females and 60 males; mean age: 77.58 years). Ground sections were prepared for each region using the ‘sawing and grinding’ technique. The following standard structural histomorphometric parameters were determined using a semiautomatic image analysis: trabecular bone volume, trabecular thickness, trabecular number, trabecular separation, and the trabecular bone pattern factor, which describes the connectedness of cancellous bone structures. Also, the maximum height of the jaw section was determined, to detect any possible correlations between vertical height and histomorphometric parameters.

Results: All the histomorphometric parameters examined showed an unexpectedly huge range of variation. The mean trabecular bone volume ranged between 20.9% and 36.9%. The mean trabecular thickness showed values between 165.9 and 224.7 μm. The mean trabecular number ranged between 1.22 and 1.77/ mm, and the mean trabecular separation ranged between 436.7 and 720.0 μm. The mean trabecular bone pattern factor showed values between −0.05 and −3.01/ mm. The maximum height of the jaw sections showed values between 16.05 and 23.42 mm. The trabecular bone volume, thickness, number and connectivity were significantly lower in the molar region than in the incisal and premolar regions. Significant sex‐specific differences were found in all the regions, female mandibles showing a smaller amount and lower connectivity of cancellous bone than male mandibles. No correlation could be found between the maximum height of the jaw and the histomorphometric parameters of the cancellous bone.

Conclusion: A possible explanation for the difference in the density between the incisal and the molar region may be that molars are generally lost at an earlier age than anterior and premolar teeth. As a result, atrophy‐related resorptive and remodeling processes commence earlier and progress further in this region than in the anterior and premolar regions. Sex‐specific differences are probably due to an increased postmenopausal bone loss of the females.
Influence of varnish application on a tissue conditioner: analysis of biofilm adhesion
Authors: Boscato Noéli , Delavi Julian Delarozieri , Muller Leonardo , Pereira‐Cenci Tatiana , Imanishi Soraia Watanabe
Published: March 2009

doi:10.1111/j.1741‐2358.2009.00290.x
 
Influence of varnish application on a tissue conditioner: analysis of biofilm adhesion

Purpose:  The aim of this study was to evaluate if the use of a varnish on a tissue conditioner would affect biofilm adhesion.

Background:  After the surgery has been performed, before the delivery of a complete denture, it is often necessary to use materials such as tissue conditioners on the surgical wound. However, these materials present deficient physico‐mechanical properties, which allow biofilm development.

Methods:  Forty elderly volunteers wearing complete maxillary dentures were selected. They were randomly allocated into two groups (n = 20), G1 and G2. In both groups, a silicone‐based tissue conditioner was placed in a recess created at the base of the denture, according to the manufacturer’s guidelines. In group G1, a varnish was applied to the tissue conditioner, while in group G2, no treatment was applied. All volunteers performed daily hygiene of the prosthesis with a soft toothbrush, and toothpaste. Quantification of the mean score values of biofilm formed at different time points (baseline, 1 week and 3 weeks) was statistically analysed using anova (α = 0.05).

Results:  Group G2 (1.6 ± 1.2) showed the lowest mean score values of biofilm formation and there was a statistical difference between the groups (p = 0.03). The highest mean score values were found after 3 weeks (2.7 ± 1.4) and were statistically different from the other time points studied (baseline and 1 week).

Conclusion:  The use of a varnish had a detrimental effect on the tissue conditioner studied, allowing higher biofilm formation.
Characterization of 14 microsatellite DNA markers for the tropical forest tree Virola surinamensis (Rol.) Warb. (Myristicaceae)
Authors: DRAHEIM HOPE , CUI MELISSA , DICK CHRISTOPHER W.
Published: March 2009

Fourteen microsatellite DNA markers were developed for studies of gene flow in the Neotropical rain forest tree Virola surinamensis. The loci were unlinked and polymorphic in a sample of 21 individuals, with two to 10 alleles per locus and observed heterozygosity ranging from 0.14 to 0.76. The overall exclusion probability (0.997) indicates high resolution for parentage‐based analyses of gene flow.
A Frazzled/DCC-Dependent Transcriptional Switch Regulates Midline Axon Guidance
Authors: Yang Long , Garbe David S. , Bashaw Greg J.
Published: March 2009

Stop-Go Axon Crossing

Developing axons may or may not cross the body's midline according to a balance between repulsive and attractive guidance factors. As an axon first approaches the midline, a repressive receptor encoded by the
comm
gene is inactivated by relocation within the cell. After the axon crosses the midline, the repressive receptor is reactivated, keeping the axon from crossing back.

Yang
et al.

(p.
944
, published online 26 March; see the Perspective by

Kidd

) now show that in
Drosophila
the
comm
gene is regulated by the attractive receptor known as Frazzled. The Frazzled protein thus functions in two ways: It initiates attraction in response to a ligand and it activates transcription of the
comm
gene, keeping the repressive signal out of the action.
A CHARACTERIZATION OF Bn(q) BY THE SET OF ORDERS OF MAXIMAL ABELIAN SUBGROUPS
Authors: AHANJIDEH N. , IRANMANESH A.
Published: March 2009

Let n = 2m ≥ 4 and let q be a power of a prime p. We prove that the simple group Bn(q) is uniquely determined by the set of orders of its maximal abelian subgroups.
INVARIANT PATTERN RECOGNITION USING RIDGELET PACKETS AND THE FOURIER TRANSFORM
Authors: CHEN G. Y. , BHATTACHARYA P.
Published: March 2009

In this paper, we propose two novel invariant algorithms for pattern recognition by using ridgelet packets and the Fourier transform. Ridgelet packets provide many orthonormal bases that can effectively capture directional features present in pattern images. The Fourier transform is good at eliminating the orientation differences. By combining these two tools, very efficient rotation invariant pattern recognition techniques are created. Experimental results show that the proposed methods achieve very high classification rates and they outperform other state-of-the-art methods for rotation invariant pattern recognition under both noise-free and noisy environments.
Nitrification‐Denitrification Biological Treatment of a High‐Nitrogen Waste Stream for Water‐Reuse Applications
Authors: Jackson W. Andrew , Morse Audra , McLamore Eric , Wiesner Ted , Xia Shu
Published: March 2009

This research was conducted to evaluate the use of biological nitrification‐denitrification systems as pre‐processors for recycling wastewater to potable water in support of space exploration. A packed‐bed bioreactor and membrane‐aerated nitrification reactor were operated in series with a 10:1 recycle ratio over varying loading rates. The dissolved organic carbon (DOC) removal exceeded 80% for all loading rates (θ = 1 to 6.8 days), while total nitrogen removal generally increased with decreasing retention time, with a maximum removal of 55%. The degree of nitrification generally declined with decreasing retention time from a high of 80% to a low of 60%. Maximum DOC and total nitrogen volumetric removal rates exceeded 1000 and 800 g/m 3 · d, respectively, and maximum nitrification volumetric conversion rates exceeded 300 g/m 3 · d. At low hydraulic loading rates, the system was stoichiometrically limited, while kinetic limitations dominated at high hydraulic loading rates. Incomplete nitrification occurred at high loading rates, likely as a result of the high pH and large concentrations of ammonia.
Surface Science Approaches to Molecular Nanostructures
Authors: Treier Matthias , Fasel Roman
Published: March 2009

The self-assembly of large organic adsorbates on solid surfaces is driven by subtle energy balances between adsorbate–adsorbate and adsorbate–substrate interactions. Understanding these interactions is a key step towards the rational design and large-scale production of
ordered, two-dimensional organic nanostructures which may find applications in (opto)electronic devices, sensors and surface catalysts. Due to the reduced dimensionality at surfaces, new phenomena arise which can only be understood by combining both experimental and theoretical methods and
knowledge from chemistry and physics. In this short review, we illustrate the richness of surface chemical phenomena at the hand of four case studies which are selected to highlight the potential as well as the current limitations in controlling molecular self-assembly at surfaces.
Comparison of the efficacy of the cervex brush and the extended-tip wooden spatula with conventional cytology: A longitudinal study
Authors: Whitaker Caroline J , Stamp Elaine C , Young William , Greenwood Lesley A
Published: March 2009

Background:

Within the United Kingdom, the change from conventional to liquid based cytology (LBC) has brought with it the universal introduction of broom style samplers, as represented by the Cervex sampler. The aim of this study was to assess whether or not there were benefits associated with a change from wooden spatulae to broom style samplers for those countries where conversion to LBC might not be readily available or is not fully supported.

Methods:

A longitudinal study was designed to compare the performance of Cervex brushes and extended-tip wooden spatulae as sampling devices for conventionally prepared cervical smears. General Practices serving the population of Hull and East Yorkshire (UK) were provided with Cervex brushes for a period of nine months to routinely collect cervical smears. The results of 66,931 cervical smear tests were compared between those practices that were using extended-tip wooden spatulae before the trial and then returned to their use afterwards, and those who were previously using Cervex samplers and continued to use them throughout. Analyses comparing both specimen inadequacy, as recorded on the standard cervical screening request form (HMR101), and also the presence of identified transformation zone (TZ) elements in smears, both indicated significant advantages associated with the Cervex brush.

Results:

Inadequate smears decreased from 5.96% with extended-tip spatulae to 4.77% with Cervex brushes (p<0.001) and increased back to 7.34% when practices reverted to extended-tip spatulae after nine months. Under the same conditions, the proportion of smears containing identified TZ elements increased from 50.52% to 54.75% (p<0.001), before reverting to 45.47% (p<0.001). In contrast, for a control group of practices using the Cervex brush throughout, inadequate smears decreased in all phases of the study, with no significant variation in TZ sampling rates.

Conclusions:

Using the Cervex brush with conventional cytology significantly decreases inadequate smears and increases TZ sampling when compared to the extended-tip spatula and can offer improved cervical screening in countries unable or unwilling to convert to LBC.
Bioremediation
Authors: Philp Jim C , Atlas Ronald M , Cunningham Colin J
Published: March 2009

Bioremediation refers to the clean‐up of pollution from soil, groundwater, surface water and air using biological, usually microbiological, processes. It has left the laboratory and is established in some parts of the world, especially the USA, as a full‐scale, biotechnology‐based industry.
Mikrostrukturierte Festbettreaktoren für stark exotherme Gasphasenreaktionen: Eine Machbarkeitsstudie
Authors: Güttel R. , Turek T.
Published: March 2009

Mikrostrukturierte Festbettreaktoren für partielle Oxidationsreaktionen wurden durch mathematische Modellierung und Simulation untersucht und mit konventionellen Rohrbündelfestbettreaktoren verglichen. Als Beispielreaktion diente die partielle Oxidation von Butan zu Maleinsäureanhydrid. Die Simulationsergebnisse zeigen, dass eine Steigerung der auf das Reaktorvolumen bezogenen Produktivität um einen Faktor von bis zu 5 in mikrostukturierten Festbettreaktoren zu erzielen ist. Dies lässt sich im Wesentlichen auf den erhöhten Reaktorwirkungsgrad durch geringere Wärme‐ und Stofftransportwiderstände zurückführen. Durch geeignete Wahl der Katalysator‐Partikelgröße und der Länge des Festbetts kann der Druckverlust begrenzt werden. Der Beitrag unterstreicht, dass mikrostrukturierte Festbettreaktoren ein großes Potenzial zur Intensivierung großtechnisch durchgeführter stark exothermer Reaktionen aufweisen.
Modellrechnung für die heterogen katalysierte Epoxidierung von 1,3‐Butadien zu 3,4‐Epoxy‐1‐buten im Labor‐Rohrreaktor
Authors: Otto T. N. , Mas C. , Ederer H. , Powietzka B. , Dinjus E.
Published: March 2009

Auf Basis von elementaren Reaktionen wird ein mathematisches Modell erstellt, das den Einblick in das chemische Geschehen der heterogen katalysierten Epoxidierung von 1,3‐Butadien am Ag‐Katalysator im Labor‐Rohrreaktor ermöglicht. Dazu wird der Reaktionsmechanismus auf ein System von 29 gekoppelten Differentialgleichungen transformiert. Insgesamt ergibt sich ein Reaktionssystem aus 56 Reaktionen, die alle über eine komplexe Verbindung mit dem aktiven Zentrum (Z) des Katalysators verfügen. Jede Reaktion des Systems besteht aus zwei Arrhenius‐Parametern (präexponentieller Faktor und Aktivierungsenergie), sodass sich insgesamt 112 Parameter ergeben. Der erforderliche Datensatz wird aus Experimenten extrahiert, die im Labor‐Rohrreaktor durchgeführt werden. Für die Epoxidierung wird ein Ag‐Katalysator eingesetzt, der durch simultane Nassimprägnierung (Incipient wetness method) eines α‐Al2O3‐Trägers mit wässriger Aktivkomponentenlösung (AgNO3, CsNO3, Ba(NO3)2) hergestellt wird. Die Versuche finden anhand ausgewählter Temperaturpunkte unter isothermen Bedingungen für die Raumgeschwindigkeiten 2950 und 5900 h–1 bei Umgebungsdruck statt. Für die signifikantesten Produkte 3,4‐Epoxy‐1‐buten, CO2 und CO stimmen die modellierten mit den experimentellen Werten gut überein. Aus dem Modell ergibt sich für die Entstehung des molekularen Zielproduktes 3,4‐Epoxy‐1‐buten aus dem komplexen Oberflächenzentrum (Z) eine Aktivierungsenergie von 26,02 kJ/mol.
Scale‐up examination of spouted bed dryers
Authors: Németh J. , Pallai E. , Aradi E.
Published: March 2009

Comparison of experimental results with predictions of the main hydrodynamic characteristics used for the sizing of spouted bed dryers are made. Various new equipment constructions are demonstrated together with operating experiences, both with an emphasis on scale‐up.
Modeling of slurry flow: The effect of particle size
Authors: Roco M. C. , Shook C. A.
Published: March 2009

A system of differential equations to obtain concentration and velocity distributions for quasi‐uniform particle slurry flows is presented. Numerical solutions for various flow conditions have been obtained using an explicit algorithm. A “supported load” concept is proposed to explain the type of interaction through contact between solid particles in neighboring layers or between particles and the pipe wall. In the analysis, the relative contributions of terms describing turbulent shear stresses, particle interactions, and mixing effects vary with the dimensions of solid particles.

The approach is tested for four kinds of sand of narrow size distributions (d = .65 mm, .48 mm, .52 mm and 13 mm), flowing with water in pipelines of various diameters (between 50 and 500 mm), at concentrations below 40% by volume. The coefficients used to estimate local parametes of the two‐phase model are related to particle diameter. A comparison of numerical predictions and measurements of concentrations, velocities and headlosses shows the applicability of the model and the possibility of extrapolating available experimental results.
Isothermes d'adsorption de l'ion chromique sur l'hydroxyde de titane fraîchement précipité
Authors: Lortie Robert , Klvana Danilo , Paris Jean
Published: March 2009

A laboratory experiment has been made on the adsorption of the Cr3+ ion on freshly‐precipitated titanium dioxide, in order to determine the effect of the concentrations of the Cr3+ and H+ ions in solution on the amount of the adsorbed chromium. The adsorption isotherms have been determined at 5 pH's (3.25 to 4.25). The adsorption at each pH is well shown by the Langmuir isotherm; it could be generalized by expressing the two parameters of the equation in function of the H+ proton activity: the maximum adsorption capacity may be represented by a second‐degree polynomial (1/verbar;Hverbar;) and the adsorption constant by a power law.

The general model proposed is the following:

where X and C represent the adsorbed chromium concentration and the chromium concentration in solution, respectively.

The aforesaid study has permitted to explain the coprecipitation of chromium (III) and titanium (IV) during the continuous neutralization of an industrial effluent containing both metals.