bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of spatial and temporal variations in the computation of radiative forcing due to sulphate aerosols: A regional study
Authors: Myhre Gunnar , Jonson Jan E. , Bartnicki Jerzy , Stordal Frode , Shine Keith P.
Published: October 2002

A high‐resolution regional model for sulphate aerosols is used to investigate the effects of spatial and temporal averaging of radiative forcing. Mie theory is used to calculate the aerosol optical properties. The strong hygroscopic growth with increasing relative humidity is taken into account. The results for the regional area selected in our study (Europe and much of the North Atlantic) show that earlier global studies may have underestimated the magnitude of the radiative forcing due to sulphate aerosols by up to 30–40% due to coarse spatial and/or temporal resolution, at least over certain regions. This underestimation in global models of the water uptake is important for all strongly scattering hygroscopic aerosols. Our results imply that representation of relative humidity at even higher spatial resolution than used in this study may be of importance. This could be incorporated in models using subgrid‐scale parametrizations of the relative humidity. Copyright © 2002 Royal Meteorological Society.
Third‐order transport due to internal waves and non‐local turbulence in the stably stratified surface layer
Authors: Zilitinkevich Sergej S.
Published: October 2002

Until recently the concern of the traditional theory of the atmospheric stable boundary layer (SBL) was, almost without exception, the nocturnal SBL developing after sunset on the background of a neutral or slightly stable residual layer. In the nocturnal SBLs the nature of turbulence is basically local. Its lower portion is well described by the classical Monin–Obukhov surface‐layer similarity theory. Things are different in long‐lived SBLs situated immediately below the stably stratified free flow. Here, the surface‐layer turbulence is affected by the free‐flow Brunt–Väisälä frequency, N. The surface layer represents approximately one‐tenth of the SBL, so that it is separated from the free atmosphere by the upper nine‐tenths of the SBL comprising hundreds of metres. Traditional concepts fail to explain such distant links. Zilitinkevich and Calanca extended the traditional Monin–Obukhov similarity theory by including N in the surface‐layer scaling, and provided experimental evidence in support of this extension. In the present paper, physical mechanisms responsible for non‐local features of the long‐lived SBL turbulence are identified as: radiation of internal waves from the SBL upper boundary to the free atmosphere, and the internal‐wave transport of the squared fluctuations of velocity and potential temperature. The third‐order wave‐induced fluxes are included in an advanced turbulence‐closure model to correct the wind and temperature profiles in the surface layer. The model explains why developed turbulence in the surface layer can exist at much larger Richardson numbers than the classical theory predicts. Results from the new model are in good agreement with the extended similarity theory and experimental data. Copyright © 2002 Royal Meteorological Society.
Can Expected Utility Theory Explain Gambling?
Authors: Hartley Roger , Farrell Lisa
Published: October 2002

We investigate the ability of expected utility theory to account for simultaneous gambling and insurance. Contrary to a previous claim that borrowing and lending in perfect capital markets removes the demand for gambles, we show expected utility theory with nonconcave utility functions can explain gambling. When the rates of interest and time preference are equal, agents seek to gamble unless income falls in a finite set of values. When they differ, there is a range of incomes where gambles are desired. Different borrowing and lending rates can account for persistent gambling provided the rates span the rate of time preference.
Data Watch: Research Data from Transition Economies
Authors: Filer Randall K , Hanousek Jan
Published: October 2002

This section will offer a description of data sources that may be of interest to economists. The purpose is to describe what data are available from those sources, what questions can be addressed because of the unique features of the data, and how an interested reader can gain access to the data. Suggestions for data sources that might be discussed here (or comments on past columns) can be sent to William N. Evans, c/o Data Watch, University of Maryland, Department of Economics, College Park, Maryland 20742, or they can be e-mailed to 〈 evans@econ.umd.edu 〉.
Recommendations for Further Reading
Authors: Saffran Bernard
Published: October 2002

This section will list readings that may be especially useful to teachers of undergraduate economics, as well as other articles that are of broader cultural interest. In general, the articles chosen will be expository or integrative and not focus on original research. They may include survey articles, discussion of related subjects in which economists might have an interest, or analyses of economics from other perspectives. If you write or read an appropriate article, please send a copy of the article (and possibly a few sentences describing it) to Bernard Saffran, c/o Journal of Economic Perspectives, Department of Economics, Swarthmore College, Swarthmore, PA 19081.
Institutional Determinants of Labor Reallocation in Transition
Authors: Boeri Tito , Terrell Katherine
Published: October 2002

The transition process differed in the countries of the Former Soviet Union (FSU) and those of Central and Eastern Europe (CEE) in terms of reallocation of labor real wage, employment and output adjustment. We sift through the theoretical and empirical literature to find an explanation for these diverging adjustment trajectories and conclude that they can be explained by the fact that the CEE countries adopted social policies that upheld wages at the bottom of the distribution forcing the old sector to restructure or collapse while the FSU countries allowed wages to free-fall not forcing the hand of the old sector.
Comments
Authors: Watt Richard , Rabin Matthew , Thaler Richard H
Published: October 2002

To be considered for publication in the Comments section, letters should be relatively short—generally fewer than 1000 words—and should be sent to the journal offices at the address appearing inside the front cover. The editors will choose which letters will be published. All published letters will be subject to editing for style and length.
Buried Gas Hydrates in the Deepwater of the South Caspian Sea, Azerbaijan: Implications for Geo-Hazards
Authors: Diaconescu Camelia C. , Knapp James H.
Published: October 2002

Two multi-channel seismic reflection profiles in the deepwater of the South Caspian Sea, offshore Azerbaijan, document one of the first examples of buried gas hydrates. Based on their geophysical signature, these clathrates are characterized by (1) a depth-restricted, lenticular body well beneath the seafloor, (2) the apparent accumulation of free gas within the underlying sediment, and (3) evidence of associated recent slope failure in the overlying strata. The interpreted thickness and depth of gas hydrates in the South Caspian Basin fall within the hydrate stability field predicted from the rmobaric modelling of gas compositions identified from coring at the seafloor. Predicted minimum water depths (∼150 m) and maximum thicknesses (1,300 m) for hydrate stability are much shallower and considerably thicker in the South Caspian Sea than for other known hydrate occurrences. Accumulation of these hydrates near the base of the continental rise appears to control a large region (> 200 km2) of shallow deformation, here named the Absheron allochthon. Such attributes make these gas hydrates important, and perhaps previously underestimated, geo-hazards of the South Caspian region. Primary among these hazards are (1) uncontrolled release of free gas trapped beneath the hydrate seal, (2) disruption of the gas hydrate stability field leading to either explosive dissociation of the gas hydrate, or (3) reduction in sediment strength, slope instability, and mass sediment transport. Documentation of the presence and distribution of gas hydrates, especially when concealed at depth in the subsurface, is a clear pre-requisite for exploration activities in the deepwater region of the South Caspian Sea.
Oil and Gas Production and Consumption in Turkey
Authors: Kaygusuz Kamil
Published: October 2002

Turkey has dynamic economic development and rapid population growth. It also has macroeconomic, and especially monetary, instability. The net effect of these factors is that Turkey's energy demand has grown rapidly almost every year and is expected to continue growing, but the investment necessary to cover the growing demand has not been forthcoming at the desired pace. On the other hand, Turkey's strategic location makes it a natural “energy bridge” between major oil and gas producing areas in the Middle East and Caspian Sea regions on the other hand, and consumer markets in Europe on the other. Oil consumption has increased in recent years in Turkey, and this trend is expected to continue, with growth of 2–3 % annually in coming years. Oil provides around 43 % of Turkey's total energy requirements, but its share is declining (as the share of natural gas rises). Around 90 % of Turkey's oil supplies are imported, mainly from the Middle East and Russia. On the other hand, current gas production in Turkey meets 2.8 % of domestic consumption requirements. Turkish natural gas is projected to increase dramatically in coming years, with the prime consumers expected to be industry and power plants. Turkey has chosen natural gas as the preferred fuel for the massive amount of new power plant capacity to be added in coming years.
Characteristics of Agriculture Tractor Interior Noise
Authors: Abd-El-Tawwab Ali M. , Abouel-Seoud S.A. , El-Sayed F.M. , Abd-El-Hakim T.A.
Published: October 2002

The study in the present paper was carried out when a fabricated cab was added to an agricultural tractor. The fabricated cab was selected after a comprehensive series of experimental tests carried out on a variety of cab constructions. The noise measurements were taken from the experimental tests, while the tractor was driven either by the chassis dynamometer in the laboratory or on a farm road surface. The results are discussed from the view point of obtaining the influence of the tractor driving parameters (road speed, gear-shift, engine speed and tractive effort) on the noise measured inside the tractor cab at the operator's head position in terms of sound pressure level and analysed over the frequency range up to 2000 Hz. In addition, rubber pads were used between the fabricated cab and the tractor floor to control noise. The results indicate that the tractor driving parameters affect the noise measured within the tractor cab. Moreover, the road surface roughness or the type of farm surface also produced a significant effect on the measured interior noise.
High Amplitude Infrasound in Railway Tunnels
Authors: Sisto Renate , Lenzuni Paolo , Pieroni Aldo
Published: October 2002

This paper addresses the issue of ultra-low frequency sound waves inside railway tunnels. The infrasound spectrum shows two main features: 1) a Kolmogoroff −5/3 slope above a critical frequency and a flat spectrum below; 2) distinct resonance peaks at the tunnel axial eigenmode frequencies. These features suggest that a turbulent velocity pattern is induced by the velocity shear produced by the entry and exit of the train. The turbulence acts as a source for the acoustic wave equation in a cylindrical cavity. The spectral peaks at the cavity eigenfrequencies are due to the development of stationary waves. A power law p ∝ vα has been used to represent the functional dependence of peak pressure wave amplitudes on average train velocities in tunnels. Our data only suggest a value of α between 1 and 1.5. Total exposure times above 140 dB are of the order of 10 minutes/day. Values are below the hearing impairment threshold for continuous exposures of similar duration. One pressure peak exceeding 150 dB has been measured in association with a train encounter inside the tunnel.
Measurement of Granular Fill Compaction Using Low Frequency Vibration Testing
Authors: Zagyapan M. , Fairfield C. A. , Sibbald A. , Bensalem A.
Published: October 2002

This paper describes the use of an instrumented impact hammer test for density measurement in a granular soil (Specification for Highway Works Type 1 fill) whilst monitoring the performance of vibro-tamper compaction. A 3–D finite element model was also used as a predictor. The effect of varying key material properties was studied. An increase in the soil's modulus of elasticity resulted in higher natural frequencies. An impact hammer, fitted with a force transducer, was used to excite the soil whose response was measured by accelerometer and analysed in both time and frequency domains. The change in natural frequencies of the modes of soil vibration was observed after each pass of a vibro-tamper. A sudden increase in natural frequencies was observed after the first pass; this effect reduced with compaction. Shear wave velocities were used to calculate a low strain modulus of elasticity and a correlation was established with the modulus of elasticity derived from Clegg hammer impact values. The same type of tests were applied to understand the field attenuation characteristics of Type 1 fill. There was a slight decrease in the maximum amplitude of the shear waves with increasing compaction; high attenuation of shear waves was also noted.
Infrasound Pressure Meter and Examples of Measuring Data
Authors: Iwahashi Kiyokatsu , Ochiai Hiroaki
Published: October 2002

Recently, complaints about low frequency noise are increasing in Japan. In Inter-Noise ′99, Ochiai has reported the following three kinds of evaluation methods for effects caused by infra and low frequency noise.

An evaluation for rattling of doors or windows. An evaluation for psychological and sleep effects An evaluation for oppressive or vibratory sensation.

We have developed a measuring instrument corresponding to the above evaluation methods. In this report, an outline of the instrument and examples of infra and low frequency noise data are introduced.
A Numerical Approach of Self-Sustained Tone Generation and Reduction in Ducts
Authors: Coiret A. , Guerin S. , Sakout A. , Henry R.
Published: October 2002

Starting from numerical models which are used in engineering, it is shown that it is possible to bring to light the main features which are responsible for the generation of self-sustained tones in turbulent flows.

The numerical study is based on our experimental results. The set-up consists of two diaphragms in tandem in a duct, leading to self-sustained tones up to 150 dB.

The modelled flow is assumed to be incompressible. It does not allow estimation of noise levels. However the calculation of the flow field exhibits the necessary conditions for the conversion of the kinetic energy towards the acoustical field.

An initial stationary model shows the location of the acoustical source. A second non-stationary L.E.S. model describes the dynamics of the detachment and impingement of the coherent structures.

An experimental noise reduction method is performed. The numerical approach contributes an explanation of the noise reduction mechanism.
Advanced Hydro-Pneumatic Semi-Active Suspension System
Authors: El-Tawwab Ali M. Abd
Published: October 2002

Automotive suspension design is a compromise brought about by the conflicting demands of ride and handling. The past few years have seen the introduction of increasingly sophisticated, electronically controlled, components into automotive suspensions which redefine the boundaries of the compromise. This paper suggests a simple solution for eliminating discomfort by using an advanced hydro-pneumatic semi-active suspension system which involves modifications to the twin-accumulator suspension system and conventional passive suspension system without either excessive cost nor complexity. Moreover, the paper provides a theoretical evaluation of the advanced hydro-pneumatic semi-active suspension system suggested, and compares the results obtained to those given by the twin accumulator system and the conventional passive suspension system. As a result the advanced hydro-pneumatic semi-active suspension system gives worthwhile improvements when compared to the conventional passive suspension system, and twin accumulator suspension system.
Ambulance Stretcher with Active Control Isolator System
Authors: Abd-El-Tawwab Ali M.
Published: October 2002

This paper considers the theoretical design of support systems for a stretcher, whilst being transported in an ambulance, in order to reduce vibration-induced discomfort. However, travelling on normal roads at high speeds results in an ambulance and its occupants being subjected to vibration. To avoid this problem ambulances often travel at very low speeds causing traffic congestion and delaying the patient's arrival at hospital. Ambulance suspension systems often give poor ride comfort, which may result in deterioration in the condition of injured patients. Suspension of the ambulance stretcher itself is a lower cost option than a purpose built ambulance suspension system and may offer superior isolation of the patient from road surface disturbances. This paper describes the development of a hydro-pneumatic stretcher suspension system, in order to reduce vibration-induced discomfort. Rubber, hydro-pneumatic, slow-active and active isolators systems are presented to support the stretcher/patient, allowing motion relative to the vehicle chassis. Also, theoretical models of these systems are compared to improve the patient's ride comfort.
Experiments on the Active Control of Circular Disk Vibration
Authors: Qiu Jinbo , Huang Xieqing , Wang Daqing , Xiong Youlun
Published: October 2002

The circular disk is a basic mechanical element, which is used widely in industry such as in turbine machines, circular saws and computer memories. Considering the requirements for an actuator to control the transverse vibration of a circular disk, a non-contact electromagnetic actuator which can produce a large actuating force is used, and a complete control system which is composed of analog components is built. Good experimental results are obtained by using the control system to control the transverse vibration of a circular disk.
Cyclical Wave-Bolt
Authors: Arabadzhi Vladimir V.
Published: October 2002

The conceptual possibilities of the design of thin absorbing (non-reflecting) coatings are considered using simple acoustical and mechanical models. Coating presents a thin layer with microscale stratification and fast time binary modulation of parameters following several algorithms of so-called cyclical wave-bolts. Algorithms of space-time modulation of the controlled layer's structure are thoroughly investigated for the one-dimensional boundary problem. These algorithms present: (a) control of boundary conditions in the discrete points; (b) control of the velocity of wave propagation; (c) control of the viscosity in layers. The algorithms do not require any measurements of the wave field and this removes the traditional stability problem for active systems. All kinds of control assume the existence of sufficient mechanical support or «vibrostat». Most of the algorithms of parametric control considered are converting low frequency incident waves into high frequency waves of technological range for which the waveguiding medium is assumed nontransparent (absorptive). Conditions for the effective application of all algorithms suggested have been formulated. It is shown that the absorbing layer can be arbitrarily thin relating to the minimum space scale of the incident wave and ensures effective absorption over a wide frequency range (beginning from zero frequency) limited only by finite space-time resolution of parametric control operations. On the base of one-dimensional boundary problems the structure of a 3-dimensional «black» parametric coating is formulated. The effectiveness of the absorbing coating does not depend on the incident wave direction. A general solution of the diffraction problem for this coating has been obtained through consideration of the object of disk shape. The possibilities of cyclical wave-bolt realization are based on the surplus of modern high space-time resolution in control, which is growing every year, relating to the space-time scales of location waves for instance remaining the same as years ago due to constant real conditions of far propagation.
Adsorption Properties of Activated Carbons Prepared from Olive Stones by Chemical and Physical Activation
Authors: Alaya M.N. , Hourieh M.A. , Youssef A.M. , El-Sejariah F.
Published: October 2002

Activated carbons were prepared from olive stones either by the addition of zinc chloride (25–50 wt%) or by gasifying non-activated carbon with steam to burn-offs between 25% and 49%. The adsorption of nitrogen at 77 K was investigated and the adsorption data interpreted by the application of the Langmuir equation, the BET equation and the αS-method. The adsorption of carbon dioxide at 273 K was also followed and the data analyzed using the DR and DA equations. The adsorption of iodine from aqueous potassium iodide solution, and of Methylene Blue and p-nitrophenol from aqueous solutions at 298 K was also determined.

Activation with zinc chloride produced physical and chemical changes which modified the thermal degradation process. Carbonization with zinc chloride restricted the formation of tars with the subsequent formation of solid carbon, the amount of zinc chloride incorporated in the precursor governing the porosity of the resulting carbon. The atmosphere under which activation of samples containing zinc chloride was undertaken was another factor in determining the texture of the carbon. Activation with steam to low burn-offs created new micropores by burning off the more reactive carbon atoms, but at high burn-offs erosion of the pore walls occurred leading to pore widening.

Adsorption from solution was determined by the solubility of the solute in the solvent and by competition for this solute between the solvent and the adsorbent. The pore size of the carbon adsorbent and the molecular size of the adsorbate molecule were prominent factors in determining the extent of adsorption from solution.
Effects of Li2O Doping on the Surface and Catalytic Properties of Co3O4–Fe2O3 Solids Precalcined at Different Temperatures
Authors: El-Shobaky G.A. , Shouman M.A. , Alaya M.N.
Published: October 2002

The effects of Li2O treatment on the solid–solid interactions and the surface and catalytic properties of the Co3O4–Fe2O3 system have been studied using TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalytic oxidation of CO by O2 at 150–350°C.

The results obtained showed that Li2O doping followed by precalcination at 500–1000°C enhanced the formation of cobalt ferrite to an extent proportional to the amount of dopant added (0.52–6.0 mol% Li2O). The solid–solid interaction leading to the formation of CoFe2O4 took place at temperatures ≥700°C in the presence of the Li2O dopant. Lithia doping modified the surface characteristics of the Co3O4–Fe2O3 solids, both increasing and decreasing their BET surface areas depending on the amount of dopant added and the precalcination temperature employed for the treated solids. The activation energy of sintering (ΔES) of cobalt/ferric mixed oxides was determined for the pure and doped solids from the variation in their specific surface areas as a function of the precalcination temperature. Both an increase and a decrease in the value of ΔES due to Li2O doping occurred depending on the amount of lithia added. The doping of Co3O4–FeO solids, followed by precalcination at 500°C, effected a significant increase (144%) in their catalytic activity towards CO oxidation by O2. Precalcination at 700–1000°C of the mixed oxide solids doped with Li2O (0.52 and 0.75 mol%) resulted in an increase in their catalytic activity which decreased upon increasing the amount of Li2O added above this limit. The activation energy of the catalyzed reaction was determined for the pure and variously doped solids studied.
The Determination of Affinity Distributions: A Numerical Algorithm and its Application for Estimating the Energetic Heterogeneity of Complexing Silicas and Humic Substances
Authors: Kholin Yu. , Myerniy S. , Varshal G.
Published: October 2002

The characterization of energetic heterogeneity has been discussed in the investigation of ion-binding and chemisorption processes. Both the calculation and the interpretation of the distribution of affinity constants are ambiguous. Methodological difficulties arise connected to the fact that electrostatic effects are difficult to separate from energetic heterogeneity because of the chemical biography of a given material. Only a close similarity between the distribution functions calculated for different ionic strengths allows the electrostatic interactions to be neglected. The numerical estimation of the distribution functions is complicated by the ill-posed nature of the problem. Some computational methods are briefly compared and methods for providing robust and unbiased estimations outlined. In contrast to differential distribution functions, the computation of integral ones may be transformed into the conventionally correct problem. On this basis, a fast and robust method for calculating integral distribution functions is proposed. In addition, this ensures numerically stable estimations of differential distribution functions. The method has been applied to a study of the energetic heterogeneity of 20 silicas chemically modified with aliphatic amines. When H+ ions are chemisorbed, the energetic heterogeneity observed is dependent on the surface topography and its hydration state. In addition, the binding properties of ashless fulvic and humic acids relative to H+, Hg2+ and Pb2+ ions have been examined. The existence of functional groups with different acidities and complexing abilities has been established.
Compatible Adsorption of Strontium and Zinc Ions as Well as Vitamins on Zeolites
Authors: Gomonaj V. , Gomonaj P. , Golub N. , Szekeresh K. , Charmas B. , Leboda R.
Published: October 2002

Adsorbents based on natural Sokyrnytsky clinoptilolite have been prepared by treating the base sorbent with aqueous solutions of different salts or acids (HCl, NH4OH or NaCl). The separate adsorption of Zr2+ and Sr2+ ions and of vitamin B1 together with the joint adsorption of Sr2+ ions and vitamin B1 has been investigated on the prepared samples. The adsorption isotherms of the cations were studied both against concentration and time, when superposition of the adsorption and desorption curves was observed. This suggests the possibility of using such adsorbents for the isolation of heavy metal ions from human organisms without simultaneous loss of vitamin B1.
Regeneration of Adsorbents by the Use of Liquid, Subcritical and Supercritical Carbon Dioxide
Authors: Grajek Henryk
Published: October 2002

The literature concerning the adsorption and desorption of environmental impurities from adsorbents by means of liquid, subcritical and supercritical carbon dioxide and the author's work on the subject have been reviewed. The influence of the adsorption and desorption temperature, the pressure and the density of the extraction solvent, the solubility of the adsorbate in the extraction solvent, the activation energy for adsorbate desorption and the particle size of the adsorbent on the adsorbate desorption efficiency by this method were discussed.
Adsorptive and Membrane-Type Separations: A Bibliographical Update (1999)
Authors: Ray Martyn S.
Published: October 2002

This paper provides a useful and quick reference source to the 1999 journal literature on adsorptive and membrane-type separations (from the 50 most important chemical engineering journals) for researchers in this area. This article continues a series of annual bibliographic updates of the literature published since 1985 (see Ray 1990–1999). The references included here have been divided into the following subject groups: theory; design data; adsorbents; PSA and cyclic systems, and applications; liquid-phase adsorption; ion exchange, chromatography and related separations; membranes; and membrane-type separations.

Adsorption and related separations for industrial and environmental applications are described in detail by Dabrowski (1999) which also contains extensive bibliographies prepared by this author. A complete bibliographic listing of the chemical engineering journal literature from 1959 to 1999 (with subsequent six-monthly updates) is available on a CD-ROM database* and full details can be obtained from the author.
Studies of the Kinetic Characteristics of HSA Adsorption by Different Types of Activated Carbon Fibres
Authors: Eretsky Eugene
Published: October 2002

Adsorption of human serum albumin (HSA) from aqueous solution on to activated carbon fibres (ACF) with different degrees of activation in the range 0–70% has been studied at 293 ± 1K. The various parameters for the porous structure were calculated by different methods on the basis of the low-temperature adsorption isotherms of nitrogen measured at 77 ± 1 K. It was shown that an increase in the degree of ACF activation led to the development of a porous structure which exhibited increasing values of the micropore and mesopore volumes. Relationships between the structure, the physicochemical properties of the surface and the adsorption characteristics of ACF were established.

The kinetic curves for HSA adsorption from aqueous solution at an initial concentration of 0.5 mg/ml were characterized by negative adsorption ranges. This phenomenon may be explained, on the one hand, by the energetic heterogeneity of the protein–surface interaction and, on the other hand, by the possibility of alterations in the conformations of the protein molecules at the interface. The latter suggestion was confirmed by the hyperchromous shift observed in the UV spectrum of the HSA solution after protein–surface contact had been established.
Carbons Suitable for Medium Pressure (6.9 MPa) Methane Storage
Authors: Quinn D.F. , Ragan S.
Published: October 2002

The storage and delivery of natural gas using adsorbent carbon monoliths at 3.4 MPa is only about 75% that of natural gas compressed to 21 MPa on an equal volume basis. One possible way to increase ambient temperature adsorbed natural gas (ANG) storage is to simply increase the storage pressure. However, this will only be beneficial if there is unfilled micropore capacity within the carbon adsorbent. Carbons that have been optimized for storage at 3.4 MPa may not have sufficient micropore capacity to give increased storage at 6.9 MPa.

In the present work, carbons have been prepared which are considered to be more useful for storage at 6.9 MPa than at 3.4 MPa due to their having an increased micropore volume fraction per monolith or storage volume. Although the pore wall separation of these carbons may not be ideal for maximum adsorbate density, these carbons showed that more than 180 v/v can be delivered from 6.9 MPa. This value approaches that of delivery from compressed natural gas (CNG) and exceeds it if the rectangular external envelope is considered as the realistic volume of the storage vessel.

The results obtained clearly show the diminishing returns for methane adsorption storage with pressure increase. An increase of only about 30% in storage capacity was achieved from a doubling of the storage pressure from 3.4 MPa to 6.9 MPa.
Adsorption of Cadmium on Transcarpathian Clinoptilolite
Authors: Vasylechko V.O. , Gryshchouk G.V. , Kuz'ma Yu.B. , Lebedynets L.O. , Oliyarnyk O.Ya.
Published: October 2002

The adsorption properties of Ukrainian Transcarpathian clinoptilolite towards aqueous cadmium(II) solutions under static and dynamic conditions have been investigated. It has been demonstrated that cadmium(II) ions are most effectively adsorbed from sulphate solutions. The value of the adsorption capacity of clinoptilolite increased as the concentration of cadmium(II) increased in solution. The dynamic adsorption capacity of clinoptilolite towards a cadmium(II) solution at pH 5.6 under optimum conditions [adsorbent modified by heating at 130–170°C for 2.5 h; diameter of zeolite grains equal to ca. 0.20–0.31 mm; rate of flow of cadmium(II) solution of 500 ng/ml concentration through adsorbent equal to 3 ml/min] was 1.25 mg/g, while at pH 10.5 this was 3.0 mg/g. The optimal mixture for the desorption of cadmium was found to be 14 volumes of HCl (1:2) to 1 volume of conc. HNO3. The extraction of cadmium under these conditions was 95%.
Study of the Sorption of Divalent Metal Ions on to Peat
Authors: Ho Y.S. , McKay G. , Wase D.A.J. , Forster C.F.
Published: October 2002

A pseudo-second order rate equation describing the kinetics of sorption of divalent metal ions on to sphagnum moss peat at various initial metal ion concentrations and peat doses has been developed. The sorption kinetics were followed based on the concentrations of metal sorbed at various time intervals. Results show that chemical sorption processes might be rate-limiting for the sorption of divalent metal ions on to peat during agitated batch contact time experiments. The rate constant, the equilibrium sorption capacity and the initial sorption rate were calculated. From these parameters, an empirical model for predicting the concentrations of metal ions sorbed was derived.
Treatment of Confectionery and Gum Factory Wastewater Effluent
Authors: Diwani Guzine El , Abd Hamman El , Hawash Salwa , Ibiari Nagwa El , Rafei Shadia El
Published: October 2002

A pilot plant for the treatment of wastewater was designed, constructed and installed for the continuous treatment of 250 l/d wastewater originating from a gum and confectionery factory. The pilot plant consisted of an equalizer, chemical mixing tank, aerator, clarifier, disinfectant tank and sand filter as the main components. In addition, a set of centrifugal and dosing pumps, an air blower and a pH controller were added.

The industrial-scale treatment unit could handle a 50 m3/d effluent flow rate composed of combined industrial and municipal wastewater effluents heavily loaded with organic and biologically resistant pollutants (sugars, gums, pesticides and detergents) with a chemical oxygen demand (COD) value extending to 25 000 ppm. House-keeping arrangements and the isolation of some streams were necessary in order to attain an end-pipe effluent capable of treatment by conventional procedures at reasonable cost values.

Different operating conditions were tested in order to treat effluent loaded with a COD value reaching 5000 ppm to obtain acceptable limits capable of containment in underground wells or re-use in irrigation.
Influence of the Hydrocarbon Chain Length of Alkylammonium Chlorides on Their Adsorption by Flotation Carriers
Authors: Streltsova E.A. , Skrylev L.D. , Tymchuk A.F. , Hromysheva E.A.
Published: October 2002

Alkylammonium chlorides whose adsorption/micelle energetic ratio (AMER) is close to unity are those adsorbed most effectively on the surface of a solid carrier (adsorbent). A change in the solution pH leads to a change in the hydrocarbon chain length of the alkylammonium chlorides with AMER values close to unity and hence to a positive change on the length of the hydrocarbon chain adsorbed on the carrier surface.
Influence of Humic Substances on the Sorption Interactions between Lanthanide and Actinide Ions and Clay Minerals
Authors: Kornilovich B. , Pshinko G. , Spasenova L. , Kovalchuk I.
Published: October 2002

Lanthanide (Eu, Nd, Gd) and actinide (Th, U) adsorption in a system consisting of fulvic acid, metal ions and clay minerals (montmorillonite, kaolinite, illite) was studied as a function of pH, metal ion concentration and fulvic acid concentration using spectrophotometric analysis and 152Eu tracer methods. Increasing metal ion adsorption on to the clay minerals was observed when humic substances were present in the system. The bridging of polyvalent metal ions between clay minerals and humic substance complexes was proposed as the possible adsorption mechanism.
Decomposition of H2O2 on Pure and ZnO-Treated Co3O4/Al2O3 Solids
Authors: El-Shobaky G.A. , Amin N.H. , Deraz N.M. , El-Molla S.A.
Published: October 2002

The effects of Co3O4 loading, precalcination temperature and ZnO treatment on the catalytic properties of the Co3O4/Al2O3 system were investigated. The amounts of Co3O4 were varied between 5.57 wt% and 32.0 wt% and the resulting solids subjected to heat treatment at temperatures in the range 400–600°C. The amounts of ZnO were varied between 0.36 wt% and 2.12 wt%. The results obtained indicated that ZnO treatment of Co3O4/Al2O3 solids followed by precalcination at 400°C resulted in a progressive decrease in the particle size of the Co3O4 crystallites in the resulting samples.

The catalytic activity of such solids towards H2O2 decomposition decreased progressively as the precalcination temperature employed was increased in the range 400–600°C. The relationship between the catalytic activity expressed as a plot of the reaction rate constant, k, versus the amount of Co3O4 in the samples showed a progressive increase in the range 5.6–17.7 wt% followed by an abrupt increase when the extent of loading exceeded this limit.

Treatment with ZnO effected a measurable increase (42%) in the specific surface area (SBET) of the treated solids. However, such treatment also resulted in a considerable increase in the value of the reaction rate constant for the catalyzed reaction. Thus, the maximum increase in the value of k20°C due to doping with 2.12 wt% ZnO attained a value of 543% while the corresponding increase in the value of the reaction rate constant per unit surface area, k̄20°C, was 331%. Precalcination at 400–600°C of Co3O4/Al2O3 solids subjected to ZnO treatment did not modify the mechanism whereby the catalytically active constituents (surface cobalt species) were involved in the reaction although their concentration was altered without affecting their energetic nature.
Surface and Catalytic Properties of the CuO/Al2O3 System Treated with Different Proportions of ZnO
Authors: El-Shobaky Gamil A. , Amin Nabil H. , El-Molla Sahar A.
Published: October 2002

The effects of ZnO treatment on the surface and catalytic properties of CuO/Al2O3 were investigated. All the samples studied contained a fixed amount of CuO (13.5 wt%) while the amount of ZnO dopant was varied in the range 0.68–6.46 wt%. The pure and variously doped solids were subjected to heat treatment (precalcination) in the temperature range 400–600°C. The samples obtained were investigated by XRD methods, nitrogen adsorption at −196°C and studies of their catalytic influence on the decomposition of H2O2 at 20–40°C.

The results obtained indicated that ZnO treatment of CuO/Al2O3 followed by precalcination at 500°C led to a progressive decrease in the degree of crystallinity of the CuO phase to an extent proportional to the amount of ZnO present in the system. This suggests that such treatment led to a significant decrease in the particle size of the CuO crystallites produced. The BET surface areas of the treated solids increased on increasing the amount of ZnO present in the system. Similarly, the catalytic activity, as expressed in terms of the reaction rate constant for the decomposition of H2O2, increased on increasing the amount of dopant added to reach a maximum value (ca. 67%) when 1.7 wt% ZnO had been added to the system, and then subsequently decreased on further addition of dopant. It was found that ZnO treatment of CuO/Al2O3 did not modify the activation energy of the catalyzed reaction but rather changed the concentration of catalytically active constituents without changing their energetic nature.
Studies of the Effect of Crosslinking in the Strongly Basic Anion Exchanger Dowex 1 and the HNO3 Concentration Employed on the Separation of the SmIII–NdIII Pair in the Polar Organic Solvent–H2O–HNO3 System
Authors: Hubicki Z. , Olszak M.
Published: October 2002

Because of their specific structure, rare earth elements are used for the modification or structural stabilization of many metallic or ceramic materials employed in modern technology and also in the metallic form, i.e. in alloys and compounds with unique properties. Industrial demand for rare earth metals has increased lately due to their new application possibilities, e.g. in supermagnets of the Nd–Fe–B type or in ceramic high-temperature superconductors. Equally, the application of rare earth elements in metallurgy, catalysis, ceramics, etc. remains of significant importance. The separation and purification of rare earth elements(III) which occur in groups with similar physicochemical properties involve extremely difficult and complex processes. Ion exchange is one method which enables such separation.

This paper presents the results of studies of the influence of the extent of crosslinking in the anion exchanger Dowex 1 and the concentration of nitric acid on the separation of the SmIII–NdIII pair by frontal analysis in 90% v/v CH3COCH3– or the CH3OH–10% v/v × M HNO3 systems. The most effective results were obtained in the 90% v/v CH3OH–10% v/v 7 M HNO3 system employing the anion exchanger Dowex 1 × 4 allowing 0.11 kg samarium(III) to be purified on 1 dm3 ion exchanger in the nitrate form and leading to a decrease in the micro-component content to a value below 10−3%.
Surface Properties of Silicas with Chemically Bonded Polyfluoroalkyl Groups
Authors: Gurevich K.B. , Roshchina T.M. , Shonia N.K. , Kustov L.M. , Ivanov A.V.
Published: October 2002

Adsorption isotherms of hexane and benzene were measured on silicas with chemically bonded polyfluoroalkyl groups and the thermodynamic characteristics of the adsorption of n-alkanes, benzene and alkylbenzenes on the same materials studied at zero coverage by gas chromatography (GC). The prepared polyfluoroalkylsilicas were also investigated by IR spectroscopy over the spectral range 6000–2000 cm−1 when it was shown that the residual SiOH groups on the silica surface do not take part in the adsorption process as the attached organic groups effectively screen them. The polyfluoroalkylsilicas exhibited an extremely low adsorption potential and high polarity relative to unmodified alkylsilicas. The specific surface areas of the chemically modified silicas could be evaluated by comparison of their GC entropy values with those calculated from an ideal two-dimensional gas model.
Elucidating the Changes in Activated Carbon Pore Structure as a Result of Tert-Butylbenzene Adsorption and its Desorption by Means of Supercritical Carbon Dioxide
Authors: Grajek Henryk
Published: October 2002

Inverse gas chromatography was applied to characterize the changes in pore structure of activated carbon samples (commercial, de-ashed, and de-ashed and oxidized) before and after the adsorption of tert-butylbenzene, and after its desorption by means of supercritical carbon dioxide. The slit-like micropore model was used for the description of the pore structure. It was shown that tert-butylbenzene was desorbed with greater difficulty from samples containing basic impurities. Changes in the amounts of surface groups (acidic and basic) during the desorption process were not significant.
Analysis of Adsorption Data of Nitrogen and Carbon Dioxide on Chemically-Activated Carbons from Cherry and Wild Cherry Stones by considering Different Approaches Based on Different Models
Authors: Alaya M.N. , Hourieh M.A. , El-Sejariah F. , Youssef A.M.
Published: October 2002

Activated carbons were prepared by activation of cherry and wild cherry stones with phosphoric acid and zinc chloride. The adsorption of nitrogen at −196°C and of carbon dioxide at 0°C was followed and the data obtained analyzed through the use of models based on theories of surface coverage and micropore filling.

Chemically-activated carbons obtained from cherry and wild cherry stones exhibited high surface areas and large total pore volumes. Most of the pores lay in the micropore region while a small fraction of the total surface area was located in non-micropores.

Fair agreement was established on comparing the textural parameters derived from models based on the theory of surface coverage with those derived from the micropore filling theory. Micropores should be classified into ultrafine pores, micropores and super-micropores, such sub-division helping in the prediction of the adsorption behaviour and in the interpretation of the data derived therefrom.
Micropore Fractal Dimension on the Basis of the Analytical Solution of the Global Adsorption Isotherm
Authors: Wojsz Roman
Published: October 2002

A Fortran program relating to the fractal parameter D was created on the basis of LMDIF programs taken from the Minpack Library and also from the book entitled Numerical Recipes in Fortran * . The fractal dimension D has been used to derive a new adsorption isotherm and the corresponding thermodynamic adsorption functions (differential molar enthalpy of adsorption, ΔH, and differential molar entropy of adsorption, ΔS).
Adsorption Properties of Zeolite-Containing Microspheres and FCC Catalysts Based on Ukrainian Kaolin
Authors: Patrylak L. , Likhnyovskyi R. , Vypyraylenko V. , Leboda R. , Skubiszewska-Zięba J. , Patrylak K.
Published: October 2002

A series of samples of zeolite-containing microspheres (ZCMS) and fluid catalytic cracking (FCC) catalysts based on Prosyana (Ukraine) kaolin were synthesized in situ. Their adsorption and chemisorption characteristics were recorded using a nitrogen low-temperature adsorption/desorption method and temperature programmed desorption (TPD) of ammonia, respectively. It was shown that changes in the synthesis conditions had a considerable impact on the micro- and meso-porosity of the samples. A low-temperature band dominated the ammonia TPD spectra of the ZCMS samples, reflecting the retention of ammonia by the sodium cations of the zeolite acting as weak Lewis acid sites. ZCMS was found to display an appreciable activity in cumene cracking at 723 K.

It was shown that during the conversion of ZCMS to FCC catalysts through the decationization and ultra-stabilization of the zeolite phase, the latter is appreciably destroyed giving rise to a considerable increase in the mesoporosity of the samples without any change in the average diameters of such mesopores.

It was concluded that the catalyst stability is characterized by pores of an intermediate (20–30 Å) diameter, thereby demonstrating the strength of the linkage between the zeolite and matrix phases.

The zeolite phase content and adsorption characteristics of catalysts prepared on the basis of Prosyana kaolin meet the demands of modern FCC catalysts.
Changes in the Surface Chemistry and Adsorptive Properties of Active Carbon Previously Oxidised and Heat-Treated at Various Temperatures. I. Physicochemical Properties of the Modified Carbon Surface
Authors: Grajek H. , Świą;tkowski A. , Witkiewicz Z. , Pakuła M. , Biniak S.
Published: October 2002

Several active carbon samples with different quantities of surface oxides were obtained by annealing previously oxidised material under vacuum at various temperatures (ranging from 180°C to 900°C). Concentrated HNO3 was used as the oxidiser. The oxygen content, the pH of the aqueous slurry and the concentration of surface functional groups were determined for all the carbons. Spectral studies (FT-IR, XPS) were performed for selected samples. The heterogeneous decomposition of hydrogen peroxide was also studied. The catalytic activity for H2O2 decomposition correlated well with the acid consumption on the carbon materials. A linear relationship was derived between the oxygen reduction potentials and the logarithm of the peroxide decomposition rate constants.