bluuebunny/crossref_metadata_2025 huggingface dataset:
Why does the brain (not) have glycogen?
Authors: DiNuzzo Mauro , Maraviglia Bruno , Giove Federico
Published: February 2011

In the present paper we formulate the hypothesis that brain glycogen is a critical determinant in the modulation of carbohydrate supply at the cellular level. Specifically, we propose that mobilization of astrocytic glycogen after an increase in AMP levels during enhanced neuronal activity controls the concentration of glucose phosphates in astrocytes. This would result in modulation of glucose phosphorylation by hexokinase and upstream cell glucose uptake. This mechanism would favor glucose channeling to activated neurons, supplementing the already rich neuron‐astrocyte metabolic and functional partnership with important implications for the energy compounds used to sustain neuronal activity. The hypothesis is based on recent modeling evidence suggesting that rapid glycogen breakdown can profoundly alter the short‐term kinetics of glucose delivery to neurons and astrocytes. It is also based on review of the literature relevant to glycogen metabolism during physiological brain activity, with an emphasis on the metabolic pathways identifying both the origin and the fate of this glucose reserve.
Incorporating short‐term outcome information to predict long‐term survival with discrete markers
Authors: Parast Layla , Cheng Su‐Chun , Cai Tianxi
Published: February 2011

In disease screening and prognosis studies, an important task is to determine useful markers for identifying high‐risk subgroups. Once such markers are established, they can be incorporated into public health practice to provide appropriate strategies for treatment or disease monitoring based on each individual's predicted risk. In the recent years, genetic and biological markers have been examined extensively for their potential to signal progression or risk of disease. In addition to these markers, it has often been argued that short‐term outcomes may be helpful in making a better prediction of disease outcomes in clinical practice. In this paper we propose model‐free non‐parametric procedures to incorporate short‐term event information to improve the prediction of a long‐term terminal event. We include the optional availability of a single discrete marker measurement and assess the additional information gained by including the short‐term outcome. We focus on the semi‐competing risk setting where the short‐term event is an intermediate event that may be censored by the terminal event while the terminal event is only subject to administrative censoring. Simulation studies suggest that the proposed procedures perform well in finite samples. Our procedures are illustrated using a data set of post‐dialysis patients with end‐stage renal disease.
Survival effect of implementing national treatment strategies for curatively resected colonic and rectal cancer
Authors: Nedrebø B S , Søreide K , Eriksen M T , Dørum L M , Kvaløy J T , Søreide J A , Kørner H
Published: February 2011

Background

The surgical management of rectal cancer has changed substantially over the past decade. There are limited data on the long-term outcome of implementing systematic management strategies.

Methods

Survival of a national cohort of patients treated surgically for colonic and rectal cancer over a 10-year interval was analysed. All 31 158 patients in Norway diagnosed with adenocarcinoma of the colon and rectum between 1994 and 2003 were identified from the Cancer Registry of Norway and the Norwegian Rectal Cancer Registry. Changes in 5-year relative survival were compared by age, stage and tumour location during the early and late years.

Results

The study population included 19 053 patients who had a curative resection. The relative 5-year survival rate significantly improved for both colonic cancer (73·8 versus 78·0 per cent; P < 0·001) and rectal cancer (72·1 versus 79·6 per cent; P < 0·001). The 5-year relative survival was significantly better for rectal than colonic cancer during the late period (P = 0·030). Improved 5-year relative survival was related to better outcomes in patients with positive lymph nodes (67·2 and 62·1 per cent for rectal and colonic cancer respectively; each P < 0·001 versus early period), but not for the subgroup aged over 75 years with lymph node-positive colonic cancer.

Conclusion

In this national cohort, survival after curative surgery for colorectal cancer increased significantly after implementation of national management strategies. Improvements were most evident for rectal cancer and in lymph node-positive disease; they were less substantial for colonic cancer and elderly patients (over 75 years). Strategic treatment changes may be warranted for the latter group.
Child sex abuse and the Irish criminal justice system
Authors: Connon Graham , Crooks Allian , Carr Alan , Dooley Barbara , Guerin Suzanne , Deasy Derek , O'Shea Deirdre , Ryan Imelda , O'Flaherty Anne
Published: February 2011

The aims of this study were to develop scales to assess experiences of sexually abused children in the Irish criminal justice system (CJS); identify aspects of the CJS which children experience as negative; compare the perceptions of children, parents and professionals of sexually abused children's experiences of the CJS; and determine correlations between perceptions of children's CJS experiences and current psychological adjustment. Forty‐three children, 101 parents, 32 mental health professionals, 27 police officers and 21 lawyers completed parallel versions of the Criminal Justice System Questionnaire (CJSQ) which assessed satisfaction with aspects of the CJS relevant to sexually abused children, specifically: Gardaí (police), medical examination, Director of Public Prosecutions, waiting for court, court professionals, court context and the CJS. Fifteen scales were developed by conducting principal component analyses. Children gave negative ratings on nine of these, and on seven children, parents and professionals differed in their perceptions of how children experienced the CJS with mental health professionals viewing the impact of the CJS as more problematic than parents and children. Scores of children and parents on CJSQ scales correlated with indices of current psychological adjustment. These results point to the importance of making the Irish CJS more child‐friendly and for evaluating these reforms with the CJSQ. Copyright © 2011 John Wiley & Sons, Ltd.
Phase‐Dependent Photochromism of a Lactone‐Stabilized Chromene from a Flavylium Reaction Network
Authors: Leydet Yoann , Gavara Raquel , Cunha‐Silva Luís , Parola A. Jorge , Pina Fernando
Published: February 2011

New trans‐2‐hydroxychalcones bearing a carboxylate group at position 2′ (Ct−) were synthesized (compounds 2 and 3). These compounds lead to a network of chemical reactions depending on pH value, light, and solvent. In water, when the pH value is lowered, the ionized trans‐chalcone is protonated and the flavylium cation AH+ is formed at very acidic pH values through hemiketal B and cis‐chalcone Cc, with global acidity constants of pK′a ≤−1 and ≈0.1, respectively, for 2 and 3. The electron‐acceptor character of the carboxylic substituent not only increases the observed acidity of the flavylium cation, but also decreases the rate of the ring‐opening/‐closing from a subsecond timescale to hours relative to model compound 1 (without carboxylate). The photochemistry of the network was studied in detail by means of continuous irradiation, monitored by UV/Vis absorption and 1H and 13C NMR spectroscopic analysis. Although compound 3 is only slightly photoactive, compound 2 (Ct−) reacts in aqueous solutions (λirr=313 nm) to form B−and Cc−, with a global quantum yield of 0.15, and fully reverts back to Ct− with a rate constant of k=6.7×10−5 s−1. The flavylium cation is no longer formed in methanol, and irradiation of Ct− leads to the formation of B− and the new lactone‐trapped chromene species La. The formation of La takes place through a sequence of three photochemical steps: photoisomerization of Ct−, photo‐ring‐closing reaction of Cc−, and photolactonization of B−. Only the cis/trans isomerization and ring‐closing reactions are thermally reversible on a timescale of seconds and hours, respectively. A photochromic system was achieved in rigid matrices of methanol (at 77 K) and 1‐dodecanol (5 °C) by irradiating lactone La to give a red ortho‐quinone allide through a photo‐ring‐opening reaction; the color disappears with a rate constant of k=1.25×10−2 s−1 in 1‐dodecanol at 5 °C.
Pincer and Diamine Ru and Os Diphosphane Complexes as Efficient Catalysts for the Dehydrogenation of Alcohols to Ketones
Authors: Baratta Walter , Bossi Gianluca , Putignano Elisabetta , Rigo Pierluigi
Published: February 2011

The ruthenium and osmium complexes [MCl2(diphosphane)(L)] (M=Ru, Os; L=bidentate amino ligand) and [MCl(CNN)(dppb)] (CNN=pincer ligand; dppb=1,4‐bis‐ (diphenylphosphino)butane), containing the N–H moiety, have been found to catalyze the acceptorless dehydrogenation of alcohols in tBuOH and in the presence of KOtBu. The compounds trans‐[MCl2(dppf)(en)] (M=Ru 7, Os 13; dppf=1,1′‐bis(diphenylphosphino)ferrocene; en=ethylenediamine) display very high activity and different substrates, including cyclic and linear alcohols, are efficiently oxidized to ketones by using 0.8–0.04 mol % of catalyst. The effect of the base and the comparison of the catalytic activity of the Ru versus Os complexes are reported. The ruthenium complex 7 generally leads to a faster conversion into ketones with respect to the osmium complex 13, which displays better activity in the dehydrogenation of 5‐en‐3β‐hydroxy steroids. The synthesis of new Ru and Os complexes [MCl2(PP)(L)] (PP=dppb, dppf; L=(±)‐trans‐1,2‐diaminocyclohexane, 2‐(aminomethyl)pyridine, and 2‐aminoethanol) of trans and cis configuration is also reported.
Minimum fluidizing velocities for coal in air
Authors: Sinclair C. G. , Robinson D. B.
Published: February 2011

This paper reviews the methods which have been proposed for evaluating the lower limit of velocity for which a fluidized bed of solids will be stable. Experimental tests for determining the minimum fluidizing velocity have been obtained for nine narrowly sized coal samples ranging from 0.0099 to 0.224 in. in diameter, and for one widely sized sample less than a No. 10 Tyler sieve using dry air at atmospheric conditions in a 5 1/2 in. diameter bed. The results are compared with those predicted using the correlations of other workers.
The phlegmatization of fine RDX
Authors: Pennie A. M. , Sterling T. S.
Published: February 2011

A successful method for phlegmatization of fine RDX has been developed. Small quantities for the phlegmatizing wax are dissolved with RDX in acetone and the wax is co‐precipitated as a very thin film on individual RDX crystals.

This method is incorporated into the technique for precipitation of fine RDX previously reported.
The upward vertical flow of air‐water mixtures: II. Effect of tubing diameter on flow‐pattern, holdup and pressure drop
Authors: Govier G. W. , Short W. Leigh
Published: February 2011

Results of visual observations and measurements of holdup and pressure drop are reported over a range of air‐water ratios for the upwards vertical flow of air‐water mixtures in four tubes with diameters ranging from 0.630 in. to 2.50 in. Tests were conducted under conditions of constant air density corresponding with an average pressure of 36 psia and at 10 constant superficial water velocities ranging from 0.0695 to 7.35 ft./sec.

The data are analyzed by the method previously suggested by Govier, Radford and Dunn involving the separation of the unit pressure drop curves into four regimes to aid in flow pattern description and the separation of the unit pressure drop itself into two components to facilitate correlation.

Tubing diameter is found to have little or no effect on the border between Regimes I and II or on the transition from the bubble to the slug flow pattern. The borders between Regimes II and III and between Regimes III and IV are markedly affected by tubing diameter as by consequence are the transitions from slug to froth and from froth to ripple flow.

Tubing diameter is found to have an important effect on the superficial friction factor and the holdup. The pressure drop data for each of the diameters have been successfully brought together in a single friction factor‐Reynolds number correlation. The holdup data are separately correlated for pressure drop Regimes I and II and for Regime III and Regime IV.
Correction factor for axial mixing in packed beds
Authors: Epstein Norman
Published: February 2011

Based on the model of a fixed bed as a series of perfect mixers, a factor is derived for correcting the logarithmic mean driving potentials in the conventional plug‐flow equations for fluid‐particle heat and mass transfer in packed beds. This factor, which accounts for axial mixing and is a measure of the transfer efficiency of the bed relative to the idealized case where axial mixing is absent, increases towards unity with bed height but decreases with ratio of terminal driving potentials.
Some procedures for the evaluation of reactor fuels and sheathing materials at chalk river
Authors: Robertson R. F. S.
Published: February 2011

In a power reactor the fuel will be operating under very severe conditions. Consequently before a fuel element can be designed it must be tested under conditions which are similar to those in the reactor, and the effect of a large number of variables on the behavior of the fuel must be investigated.

This paper discusses the fuel development program at Chalk River with special reference to the testing of uranium oxide reactor fuels in loops inserted in the NRX reactor. In these loops water may be recirculated over the test elements at temperatures up to 550°F. and pressures up to 2000 psi. The characteristics of a loop are described and the results of various tests are briefly discussed.

The testing of sheathing materials such as Zircaloy‐2 and aluminum‐nickel alloys is also described.
Conditioning of d2O in heavy water power reactors
Authors: Allison G. M.
Published: February 2011

This report indicates the problems associated with the maintenance of the purity of the D2O in a pressurized heavy water power reactor and how these problems are handled.

In a pressurized water power reactor, impurities will be introduced into the coolant and moderator from the corrosion of the steel system. These impurities are mainly particulate and colloidal in nature. They must be kept to a minimum since when circulated through the reactor they become activated by the neutron flux and when deposited throughout the system they make accessibility for maintenance difficult. Impurities may also be introduced into the water from fuel element ruptures. These also create maintenance problems since they are intensely radioactive.

Heavy water systems require a constant guard against the introduction of light water which would degrade the D2O and make the operation of the reactor inefficient or perhaps impossible. The isotopic content of the heavy water must be checked constantly. Upgrading may be required periodically or continuously.

The general purity of the water in the reactor is maintained by passing a fraction of the main circulating volume through a by‐pass containing a filter and a mixed bed ion exchange resin column. This column serves to remove ionic impurities as well as acting as an efficient filter itself. It is also used to maintain the pH of the water at the desired level whether neutral or alkaline. In the case of heavy water systems the resin must be deuterized before use to prevent degrading the D2O.
Letter to the editor
Authors: Happel John
Published: February 2011

RE: Viscous Flow in Multiparticle Systems

This abstract reviews a series of theoretical studies which has resulted in achieving a better understanding of such phenomena as resistance to flow of fluids through beds, sedimentation of small particles and viscosity of suspensions. There are many systems both in nature and technology involving these types of motion. Examples of commercial applications include the separation of particles by centrifuging and sedimentation, filtration, flow of gases through vessels containing packed solids (kilns, gas producers and blast furnaces), and motion of particles and gases in catalyst contracting vessels.
Flow of compressible fluids
Authors: Powley M. B.
Published: February 2011

Previously derived equations describing compressible flow have been rearranged in terms of known downstream conditions to facilitate determination of unknown upstream conditions. A 650 I.B.M. computor was used to solve the simultaneous equations numerically to permit construction of convenient design graphs in parametric form. Use of these graphs will eliminate a tedious trial and error computation formerly necessary with presently available methods when the upstream pressure and temperature are to be determined in gas flow problems. Application to design is illustrated by a worked sample.
High energy fuels for jet propulsion engines
Authors: Perry C. W.
Published: February 2011

Since World War II, the development of jet propulsion engines has fallen into two main categories, i.e. air breathing devices which include the turbojet and ramjet engines, and the rockets which use solid or liquid fuels. A brief review is given of the history and operating principle of each type.

The use of fuel energy for power release in jet propulsion engines is based on rate of change of momentum as the fuel is burned either with oxygen or other oxidizer. The basic power and thrust equations are presented. From these equations it is shown that high heat of combustion, ΔH, is the most significant fuel property for air breathing engines, but other properties including molecular weight of the products of combustion and temperature of combustion become equally significant for the rockets. Other desirable properties for chemical fuels are listed.

Candidate chemical fuels having higher energy release than hydrocarbons (with oxygen) are tabulated. It is shown that hydrogen, beryllium and boron hydrides have significant potentiality. Hydrogen is difficult to use. Beryllium chemicals are very toxic. Consequently, the boron hydrides and their alkylated compounds show exceptional promise. The properties of these are listed.
Catalytic reforming
Authors: Emms N. J.
Published: February 2011

This paper describes the Catalytic Reforming Process for upgrading naphtha feedstocks to high octanes using a regenerable platinum catalyst. Particular reference is made to the Powerforming Process developed by Esso Research and Engineering Company and in use by Imperial Oil Limited.

The various types of fixed bed units are described and a simplified flow plan of a typical Powerforming Unit is illustrated. The general operation of the unit is discussed as well as the primary reactions involved in catalytic reforming. Operating conditions are listed and some product yields and quality are shown in a table for various feedstocks.

Regeneration is required to reactivate the catalyst by burning off carbon and sulphur compounds laid down during the oil cycle. A general description of how this is carried out on a unit containing a swing reactor is outlined.
Distribution of residence times in continuous series of mixing zones
Authors: Buckler E. J. , Breitman L.
Published: February 2011

Tabulated numerical data, nut hitherto available, are presented for the number fraction distribution of residence times of particles in fluid which passes through a series of 1, 2, 3, … up to 75 mixing zones in series. For the special case in which the weight of particles varies linearly with time, the weight fraction distributions of residence time are also tabulated. The theory is recapitulated and extended to include the effect of recycle.
Ultimate velocity of drops in stationary liquid media
Authors: Warshay M. , Bogusz E. , Johnson M. , Kintner R. C.
Published: February 2011

The effects of high field viscosity and of low inter‐facial tension on the terminal velocity of single liquid drops falling through stationary liquid fields were investigated. Drops of tetrachloroethylene, ranging from 0.08 cm. to 1.4 cm. equivalent diameter, were allowed to fall through four different types of field fluids made by the addition of carboxy methyl cellulose, Lytron 890, corn syrup, and glycerine to water. Viscosities varied from 41.3 to 514 centipoises.

Low interfacial tension systems were ethylchloroacetate‐water, furfural‐water, and benzyl alcohol‐water with interfacial tensions of 16.43, 5.70, and 4.25 dynes per cm. respectively.

For systems of high field viscosity, the usual drag curve appears to be more useful than the correlation proposed by Hu and Kintner. For systems of low interfacial tension (below 20 dynes/cm.) and low field viscosity (of the order of one centipoise) the latter serves to correlate accurately the data of 25 systems.

A comparison of the pour technique with the usual nozzle method for the introduction of drops resulted in a terminal velocity difference of less than three percent. Wall proximity corrections were made when necessary.
Principles and operation of an air operated mixer‐settler
Authors: Mathers W. G. , Winter E. E.
Published: February 2011

A mixer‐settler for continuous countercurrent solvent extraction is described in which the mixing and pumping of the liquid phases are achieved by air streams.

The operating principles of this mixer‐settler are presented in theory and confirmed by experiment. Measurements include interface heights, capacity, air requirements and entrainment of aqueous phase in the solvent under various operating conditions.

The main advantages claimed for this unit are.

1) Mechanical simplicity and consequent freedom from maintenance.

2) Pumps and interface controllers are not required between individual stages.

3) Compactness for a given separation.

4) Low energy requirements.
Fundamental aspects of solids‐gas flow: Part I: Introductory concepts and idealised sphere motion in viscous regime
Authors: Torobin L. B. , Gauvin W. H.
Published: February 2011

This article introduces a series of analytical and critical literature surveys which deal first with the individual fundamental momentum transfer phenomena associated with particulate motion as affected by particle shape, roughness, acceleration, concentration and rotation, as well as the turbulence characteristics and boundary conditions of the transporting fluid. This information will then be used as a basis of discussion and interpretation of the many investigations of multiparticle solids‐gas conveying systems and contacting techniques reported in the literature.

This first paper reviews briefly some pertinent basic concepts of fluid mechanics, and then considers the development of the fluid velocity field and drag for single spherical particles moving rectilinearly at pre‐wake‐forming Reynolds Numbers through an infinite and undisturbed fluid.
An analysis of air and solid flow in a spouted wheat bed
Authors: Thorley B. , Saunby J. B. , Mathur K. B. , Osberg G. L.
Published: February 2011

Detailed studies of the air and solid flow patterns in a spouted wheat bed have been made in column sizes up to 2 ft. in diameter. Orifice size, cone angle, bed height and air flow were varied so as to establish their effect on these flow patterns. Air flow within the bed was obtained from pressure drop gradients, and solid flow was obtained from particle velocity measurements taken at the wall. Pressure drop, air flow distribution between spout and annulus, solid circulation rate and flow line data are summarized. A correlation is proposed which relates pressure drop and particle velocity at the top of the bed with superficial air velocity at air flows above minimum spouting. Particle velocity measurements in the spout were made from photographs, and were calculated approximately from the drag equation for a single particle.
Heats of mixing and vapor‐liquid equilibrium calculations
Authors: Lu Benjamin C.‐Y.
Published: February 2011

In the literature, when the available integrated forms of the Gibbs‐Duhem equation are employed for extrapolating vapor‐liquid equilibrium data at isobaric conditions, the relative partial molal enthalpies at constant liquid compositions, L, are assumed either to be zero or to be independent of temperature. An investigation of the temperature effect on heats of mixing for non‐ideal solutions reveals that these assumptions are invalid and that the quantity L varies linearly with temperature. Therefore the liquid activity coefficients at constant compositions should involve three temperature terms of the form a + (b/T) + c log T for extrapolating purposes. As a result, more general equations are proposed.
Influence of the presence of vapor diffusion from a wetted non‐adiabatic boundary upon the sensible heat transfer between a boundary wall and a gas stream
Authors: Hedlin C. P. , Hooper F. C.
Published: February 2011

The evaporation of a liquid from a wetted surface into a gas stream has consequences which are of fundamental importance in the analysis of sensible heat transfer at the boundary. The presence of a relatively high concentration of vapor in the region adjacent to the surface influences the physical properties of the fluid and the vapor concentration gradient affects the heat transfer mechanism.

Experimental equipment was devised to measure the sensible heat transfer coefficients at the inside surface of a porous ceramic tube from which water was being evaporated. Series of tests were carried out for non‐adiabatic wall conditions over ranges of the Reynolds Number from 5,600 to 16,000, tube diameter from 1.360 to 3.300 inches, bulk air temperature from 150 to 220°., and wall vapor pressures from 0.35 to 2.20 p.s.i.a.

Over the range of vapor pressures and evaporation rates investigated, the sensible heat transfer coefficients were not observed to depart significantly from those predicted by generally accepted relationships for the dry wall case.
The carbon dioxide‐hydrogen sulphide‐methane system: Part II. Phase behavior at 40°f. and 160°f.
Authors: Robinson D. B. , Lorenzo A. P. , Macrygeorgos C. A.
Published: February 2011

The phase behavior of the carbon dioxide‐hydrogen sulphide‐methane system, previously reported at a temperature of 100°.F.(1), has been investigated at pressures of 400, 1000, and 1600 lb./in.2abs. at 40°F. and at pressures of 1000, 1330 and 1600 lb./in.2abs. at 160°F. Correlation of the experimental data is based upon equilibrium ratios calculated for the individual components, Equilibrium ratios were found to be a function of system composition, temperature, and pressure. Deviation of the liquid phase from ideal solution behavior, as indicated by calculated activity coefficient ratios, is, in general, most dependent upon system composition at the higher pressures and lower temperatures.
Fundamental aspects of solids‐gas flow: Part III. Accelerated motion of a particle in a fluid
Authors: Torobin L. B. , Gauvin W. H.
Published: February 2011

An analysis of the extensive literature on non‐steady drag forces supports the correlation of the data by means of a total drag coefficient, which appears to be a function of the Reynolds Number and of a reduced time parameter which is related to the number of particle diameters traversed since the initiation of the motion. The added mass concept is shown to be both completely inadequate and theoretically unsound. An increase in wake turbulence resulting from Reynolds Number increases or from the occurrence of surface roughness seems to diminish the acceleration effects.

Fundamental studies of the flow fields around blunt bodies reveal the extreme complexity of the phenomena occurring during acceleration. Explanations offered for the characteristics of the non‐steady drag coefficient behavior re shown to be frequently at variances with these findings.
The incorporation of fission products into glass for disposal
Authors: Bancroft A. R.
Published: February 2011

There is need of an economical and safe method of disposing of radioactive waste produced by nuclear reactors. A method for the incorporation of fission products into glass is being studied at Chalk River. Class containing up to 50 curies of fission products per kilogram has been made during the investigation of the process. This radioactive glass has been used in stability studies in the laboratory and in the field.

Nepheline syenite (a rock containing Na, K and Al silicates) fluxed with up to 30% by weight of lime, is used as the base for the glass. A nitric acid solution of the fission products is added to a pelletized mixture of the solids. When the mixture is heated nitric acid is evaporated near 110°C. The nitrates are decomposed in the temperature range 130–600°, and the mixture is melted to form a glass at a maximum temperature of 1350°. Two of the fission products, ruthenium and cesium, are volatilized to varying degrees from the mixture during heating and create a major contamination and containment problem.

The method of processing and results obtained are discussed. The volatilized elements have been removed from the off‐gas stream by a method which permits their incorporation into glass. Scale‐up of the process to treat fission product wastes from power reactors should present no great difficulty other than design of equipment for the remote processing of large quantities of radioactive material at high temperature.
Effect of natural convection on transition to turbulence in vertical pipes
Authors: Scheele George F. , Rosen Edward M. , Hanratty Thomas J.
Published: February 2011

The effect of natural convection on transition to a disturbed flow in a heat transfer section of a vertical pipe has been investigated. The transition is related to the distortions of the velocity profile caused by natural convection. When natural convection is in the direction of forced flow the transition appears to occur through the growth of small disturbances. Transition occurs suddenly when natural convection is opposite the direction of forced flow and it appears to be associated with a separation of the flow at the wall.
Studies of bubble formation and rise
Authors: Poutanen A. A. , Johnson A. I.
Published: February 2011

Preliminary to mass transfer studies, studies of bubble shape and area during formation and of velocity of rise after formation were made for nitrogen bubbles in water and two hydrocarbon oils.

Bubble profiles were found to fit an empirical equation of the form rnθ = 1 where r and θ are polar coordinates.

Quantative studies of bubble volume and area as a function of time are reported.

A limited correlation for the velocity of rise of a chain of bubbles in a viscous oil is presented.
Kinetics of the vapor‐phase oxidation of napthalene over a vanadium catalyst
Authors: Shelstad K. A. , Downie J. , Graydon W. F.
Published: February 2011

Rates of oxidation of naphthalene were measured for the temperature range 300°C. to 335°C. using a thin layer of vanadium oxide‐potassium sulfate‐silica catalyst in a flow reactor. The amounts of naphthalene converted were determined by analysing the products for 1,4‐naphthoquinone, 1,2‐naphtho‐quinone, and phthalic anhydride. Negligible amounts of products of complete combustion were formed.

The reaction rate data obtained at low conversions of naphthalene were correlated by the following expression, based upon a model for the reaction proposed by Hinshelwood:

From the results of experiments in which the contact time was varied, it was suggested that the reaction course consisted of two parallel, consecutive reactions in which 1,4‐ and 1,2‐naphthoquinone are intermediates in the formation of phthalic anhydride.
Effect of diesel locomotive operation on atmospheric conditions in a railway tunnel
Authors: Rennie R. P. , Jegier Z. , Katz Morris
Published: February 2011

An extensive study was made over a seven day period to determine if it would be feasible, from an air pollution view point, to operate diesel locomotive powered trains through the St. Clair Tunnel. The test involved the passage of approximately 200 diesel powered freight and passenger trains through the tunnel; 3,000 air samples were taken and measurements were made on air flow and smoke density. Concentrations of carbon monoxide, nitrogen dioxide, total oxides of nitrogen, aldehydes, sulphur dioxide, carbon dioxide and oxygen were determined.

The sampling methods, sampling equipment, analytical procedures and test equipment used for this particular investigation should be applicable to a variety of air pollution problems met in the chemical industry.
Heat transfer to a surface reacting fluid in turbulent flow
Authors: Rothenberg Ronald I. , Smith J. M.
Published: February 2011

The effect of chemical reaction on heat transfer has been studied for turbulent flow in tubes of a reacting gas. The analysis is carried out for a heterogeneous, catalytic reaction occurring at the wall surface. Equations are presented for predicting the increase in heat transfer coefficient due to reaction in terms of the rate of reaction, diffusion, and operating conditions. For an exothermic reaction the total heat transfer coefficient is increased when the gas temperature is greater than the wall temperature, and decreased when the gas temperature is less than the wall value. The effect is greatest for rapid reactions; that is, when diffusion of reactants to the tube wall determines the rate of reaction.

The equations are applied to the catalytic hydrogenation of ethylene. The results show that the total heat transfer coefficient can be at least ten fold larger than the coefficient for a non‐reacting system at the same flow conditions.

In general, the results of this study suggest that a wall‐catalyzed reaction can be an effective means of increasing the heat transfer rate from gases in turbulent flow in tubes. Furthermore, for a porous catalyst applied to the wall, enlarging the thickness of the catalyst layer will increase the effect on the heat transfer rate.
Temperature dependence of the binary diffusion coefficient of gases
Authors: Scott D. S. , Cox K. E.
Published: February 2011

The variation with temperature of the binary gas diffusion coefficient for the gas pairs N2 ‐ H2 and NH3 ‐ H2 is reported for the temperature range of 0°–300°C. The data were obtained using a steady state flow method, and the apparatus and experimental conditions relative to this technique are discussed. Although this method does not give absolute values of the diffusion coefficient, it is relatively simple and accurate.

The extent of agreement of the data with equations for the prediction of gas diffusion coefficients is shown. Better results are obtained when these equations are applied to nearly ideal systems, such as the N2 ‐ H2 pair, rather than to gases which have highly polar molecules such as NH3.
Formation and quenching of nitric oxide in a continuous flow furnace
Authors: Mordell D. L. , Thompson A. L. , Yano G.
Published: February 2011

A pre‐pilot plant facility for the thermal fixation of atmospheric nitrogen has been successfully built and operated.

Gas temperatures exceeding 3000°K. have been reached but the quenching rates available to fix the nitric oxide were found to be inadequate for the gases at these high temperatures. However, yields of 3.7 nitric oxide by volume have been realized experimentally.

A separate water cooled sampling probe inserted at the top of the furnace gave quenching rates of the order of 10°C./sec. This also permitted the study of the effect of variation in the quenching rate while maintaining other conditions constant. The oxygen concentration appeared to have less effect than previous results indicated, but this may have been due to uncertainties in estimating gas temperatures near 3000°K.
The development of the alum‐amine process for the recovery of alumina from shale
Authors: Thomas G. , Ingraham T. R.
Published: February 2011

Based on a review of the extensive published literature on the recovery of alumina from clays and shale, sufficient experimental work was done on a bench scale to establish a flow sheet whereby these materials might be treated for the recovery of cell‐grade alumina. The significant step in the processing is the recovery of potassium alum, and its purification by either recrystallization or liquid‐liquid extraction.
A spouted mixer‐settler
Authors: Johnston T. R. , Robinson C. W. , Epstein N.
Published: February 2011

A new type of mixer‐settler is described wherein the heavy liquid phase is spouted upward through a depth of light liquid phase and allowed to settle below the light phase. The method does not require mechanical agitation, allows both mixing and settling to occur continuously in the same chamber, and is simple in design.

Optimum conditions have been determined for bench‐scale extraction of benzoic acid from toluene by means of a water spout. Independent variables studied were water rate, toluene rate, spout pipe diameter and wall effect. Dependent variables measured were spout height, spout spread, initial entrainment points and stage efficiency. Murphree spoutedphase efficiencies up to 96% were obtained.
Mass transfer from fluid and solid spheres at low reynolds numbers
Authors: Bowman C. W. , Ward D. M. , Johnson A. I. , Trass O.
Published: February 2011

Predicted continuous phase mass transfer coefficients for fluid and solid spheres in the Stokes region of flow are correlated as Sherwood numbers plotted against Peclet numbers. These correlations permit a study of the effect of internal circulation on the rate of mass transfer from fluid spheres. At a Peclet number of 104, the theory predicts a threefold increase in transfer due to the circulation movements within a gas bubble. At a Peclet number below 10−2, the difference between a circulating and non‐circulating (or solid) sphere is indiscernible.

The analysis presented in this paper for fluid spheres is based on a study by Friedlander (1) of mass transfer around solid spheres. A more elaborate concentration profile through the boundary layer has been used in the present investigation and the result reported for solid spheres differs about 8% from that given by Friedlander.

The more interesting details of the mathematical treatment and the machine computation of the resulting differential equations are included.
Dynamic analysis of bubble plate performance
Authors: Mickley H. S. , Gould L. A. , Schwartz L. M.
Published: February 2011

A frequency response method is examined as a possible experimental method for the simultaneous determination of liquid mixing, plate efficiency, vapor‐liquid equilibrium, and liquid holdup on a single bubble tray. The method depends upon the introduction of sinusoidal fluctuations in the concentration of a species in the liquid and vapor fed to the plate and the measurement of the induced concentration variations of the same species in the effluent liquid. It is applicable to multi‐component systems.

The analytical results used to interpret the measurements are based on a linearized model. Despite this idealization, systems exhibiting marked curvature of the liquid‐vapor equilibrium relation are adequately represented. Systems showing very significant enthalpy effects are treated quantitatively when the liquid on the plate is perfectly mixed. This is done with the aid of the “signal flow graph” technique.

With incompletely mixed plate liquid, mathematical difficulties have so far prevented the quantitative interpretation of measurements of the frequency response when enthalpy effects are large. At present it appears that the frequency response technique is limited to perfectly mixed plates, i.e., to small laboratory sized plates, or to incompletely mixed systems in which the heat effects are small, i.e., gas absorption plates and distillation systems in which the volatilities and latent heats of all components are of comparable magnitude.
Holdup in liquid‐liquid extraction columns
Authors: Johnson A. I. , Lavergne E. A. L.
Published: February 2011

A theoretical study of the countercurrent flow of a dispersed phase in a continuous phase resulted in the following equation relating holdup X to the flow rates of the two phases.

For packed towers this equation has been used in the following form:

Values of A', B', and r for three liquid pairs, and two packing types are reported, using new holdup data determined in this research.

Graphical correlations are shown and values of r are reported for some of the data of Gayler and Pratt.

For spray towers the equation suggested a correlation of \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{X^3}}{{U_D ^{1.8}}} $\end{document} against the group \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{U_C ^{0.2}}}{{U_D ^{1.8}}}\left({\frac{X}{{1 - X}}} \right)^3 $\end{document} This has been tested using data previously published by one of the authors.
Approximate solutions of conduction of heat through non‐homogeneous medium
Authors: Tien Chi
Published: February 2011

By comparing the respective difference equations of heat conduction through a homogeneous and non‐homogeneous media, an approximate analogy is established. This analogy enables the finding of the solution of conduction through a non‐homogeneous medium in terms of the known solution for homogeneous cases. An illustrative example is given to demonstrate the working details.
The explosive limits and flammability of xanthate dusts in air
Authors: Roxburgh J. M.
Published: February 2011

The minimum concentrations of xanthate dusts in air which will form explosive mixtures have been determined. Comparison with other dusts considered to be hazardous industrially indicates that xanthates of the lower alcohols should be classified as readily explosive. The explosive limit increases rapidly with particle size; dusts coarser than 150 mesh are relatively safe. Xanthate dusts are easily ignited and have very low ignition temperatures. Under conditions such that fine wood flour ignites at 540°C. the xanthates will ignite between 230°C. and 290°C.
A method of measuring the surface area of granular material
Authors: Hedlin C. P. , Collins S. H.
Published: February 2011

A method is described which permits measurement of the exterior surface areas of objects down to about 0.1 sq. in. in area. In this method, the object is coated with an adhesive and a single layer of small metal particles. The change in weight gives a measure of the external area of the object.

Systematic variations in the density of the metal particle coating are discussed, and appropriate correction factors are given.

This method is intended for use in research that involves objects whose exterior surface areas have an effect on the process being investigated. Examples are the drying of agricultural grains and foodstuffs, the comminution of ores and chemicals, and the hydraulic and pneumatic transport of materials.

The precision of the method is adequate, the root‐mean‐square error being about 1%.
Solid‐liquid equilibria in wax crystallization
Authors: Butler R. M. , MacLeod D. M.
Published: February 2011

The equilibria obtained during the crystallization of waxes has been studied theoretically and it has been found that the degree of separation between normal paraffins may be predicted, if it is assumed that the solid is an ideal solution. Results predicted from the theoretical equations have been compared with mass spectrometer analyses of recrystallized waxes and surprisingly close agreement has been found.

It has also been shown that ketone solvents have essentially the same selectivity for recrystallizing waxes as n‐hexane. The reason for this is that the activity coefficients for various n‐paraffins in a ketone solution are nearly identical even though they are all much higher than in the hydrocarbon solution.

The separation between normal paraffins in conventional single stage wax recrystallization is not very sharp. This may be improved by the use of a number of stages in a countercurrent cascade. Experimental results with such a cascade are in agreement with the theoretical predictions.

The presence of non n‐paraffinic components in some waxes can cause the formation of eutectic mixtures. This affects the separation in a manner analogous to that of hetero‐azeotropes in some distillation processes.

The crystallization of waxes from their, melts has also been studied both theoretically and experimentally. When mixtures of similar molecular weight n‐paraffins, such as n‐C21H44 and n‐C23H48 are cooled, a solid solution is formed. This is also found with mixtures of similar recrystallized waxes. On the other hand, mixtures of n‐paraffins of widely different molecular weight, such as n‐C20H42 and n‐C32H66, or hydrocarbons of different structure, such as n‐paraffins and iso‐paraffins, form separate crystals and a eutectic. Similar results are found with mixtures of commercial waxes of widely different melting point and type.
Optimum process conditions for a completely mixed multistage reactor
Authors: Kubota H. , Namkoong S. , Akehata T. , Shindo M.
Published: February 2011

A graphical method for determining the process conditions which give the minimum volume of reactor at a given outlet conversion is described, and illustrated by application to a multistage fluidized bed reactor for the catalytic oxidation of sulphur dioxide.
The application of the copper oxide‐alumina catalyst for air pollution control
Authors: Sourirajan S. , Accomazzo Mauro A.
Published: February 2011

The catalytic combustion of 1‐hexene present in diluent nitrogen in the concentrations of 1170 p.p.m. and 3000 p.p.m. by excess oxygen, has been studied in the presence of the CuO‐Al2O3 (1:1) catalyst in the temperature range 242° to 424°C. and gas space velocity in the range 4000–16,000 hr.−1. The experimental data on the kinetics of the reaction were found to fit an empirical half‐order law with respect to the 1‐hexene concentration. The presence of water vapor in the reactants was found to have no effect on the efficiency of the catalyst at temperatures higher than 400°C. The above results were similar to those obtained for the catalytic oxidation of n‐hexane studied earlier.

The possible use of the above copper oxide‐alumina catalyst for the simultaneous removal of hydrocarbons and carbon monoxide present in the auto exhaust gases has been tested, making use of a 1955 six‐cylinder Chevrolet engine run on leaded gasoline fuel. The hydrocarbon and carbon monoxide concentrations encountered in these studies varied in the range 170–16,000 p.p.m. and 1–7% respectively. It was found that the minimum initial temperature of the catalyst bed required for the complete removal of both hydrocarbons and carbon monoxide, simultaneously, was 226°C. under no load condition, 342°C. under an engine load of 2.5 h.p., 400°C. under an engine load of 5.1 h.p. or higher, and 236°C. under deceleration conditions. The catalyst showed no deterioration in performance even after 100 hours of continuous service in conjunction with the above auto exhaust gases.
A design parameter for multicomponent tray design estimates
Authors: Surowiec Alfred J.
Published: February 2011

This, report develops computational techniques that are useful in multicomponent distillation. A design parameter, (∂n/∂N)s is introduced which is numerically equal to the number of theoretical plates required to do the work of one total reflux tray at the bottom of the enriching section. For a minimum sized tower, (∂n/∂N)s is legs than 3.5. Economic conditions may permit values as high as 6.

The ratio of the number of theoretical trays, n, to the minimum number, N, for the combined enriching and stripping sections, including reboiler and condenser, and the ratio of the reflux leaving the enriching section, Ls, to the minimum reflux, LMs, can be found from:

A total of 36 sets of minimum reflux data in multi‐component systems were correlated with an average error of −4% in the ratio n/N by these equations.

Since (∂n/∂N)s is related to the relative volatility and the compositions of the counterflowing liquid and vapor streams at the bottom of the enriching section, the reflux Ls can be found from a feed tray balance. A procedure is provided for evaluating Ls after a value for the design parameter has been selected.