bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Origin of Porosity in Hydrous Zirconia Gels. III. Sodium Hydroxide as a Precipitant
Authors: Gimblett F.G.R. , Hussain A. 
Published: January 2017

When used as precipitants for the preparation of hydrous zirconia gels, aqueous NaOH solutions generate materials whose porosities are strongly dependent on their outgassing temperatures. Microporous solids exhibiting high apparent BET-nitrogen surface areas, and possessing considerable proportions of primary (narrow) micropores, are obtained at lower outgassing temperatures (<250°C). Thermal treatment above this temperature leads to the generation of mesoporous materials exhibiting little or no micropore volume. It is suggested that the ready removal of loosely-bound or absorbed water from the gel at lowertemperatures, to generate an essentially microporous structure, is catalysed by the presence of NH3 ligands. Decreasing ammonia concentration (as in the sequence NH4HCO3, NaHCO3, NaOH). coupled with increasing precipitant basicity leads to a higher proportion of strongly bound water (hydroxo ligands) in the gel. This can only be removed by outgassing at higher temperatures to yield a material which is almost exclusively mesoporous.
Benzene Hydrogenation Activities of Supported Nickel Catalysts in Relation to Their Chemisorption Properties
Authors: El-Nabarawy Th. , Attia A.A. , Hamada M.A. , Youssef A.M. 
Published: January 2017

Samples of nickel on alumina (1.1–10.4 wt.% Ni) were prepared by impregnating alumina in hydrated nickel nitrate. The textural properties of the calcined catalysts have been determined from nitrogen adsorption at 77 K. Calcined catalysts were reduced prior to determination of the chemisorbed benzene at 308 K or chemisorbed hydrogen at 383 K. Hydrogenation of benzene was also determined at 473 K using the flow technique. The surface area of NiO/Al2O3 catalysts decrease and their mean pore radii increase with an increase in NiO content. These changes are more pronounced for catalysts containing more than 5% metal. Chemisorption of benzene proceeds via the formation of π-bonds with nickel. The chemisorption of hydrogen indicated that the percentage dispersion decreases and the crystallite size increases with an increase in metal loading. Dispersion, crystallite size and metal surface are important factors in determining the activity of supported nickel catalysts for benzene hydrogenation.
Surface and Catalytic Properties of Al2O3, CuO/Al2O3 and ZnO/Al2O3 Systems
Authors: El-Nabarawy Th. , Attia A.A. , Hassan N.A. , Youssef A.M. 
Published: January 2017

Pure alumina, CuO/Al2O3 and ZnO/Al2O3 have been calcined in the temperature range 500–1000°C and the phase changes involved followed using DTA and XRD techniques. The surface properties of all the calcination products were determined from the adsorption of nitrogen at 77 K and the chemisorption of pyridine at 423 K. The catalytic conversion of isopropanol on all the thermal products was also investigated. The surface areas of CuO/Al2O3 and ZnO/Al2O3 decreased while the pore radii increased with increasing calcination temperature from 500°C to 1000°C. CuAl2O4 forms above 800°C while ZnAl2O4 crystallizes at 600°C The acidity of the surface decreased when the calcination temperature was increased above 500°C. The conversion of isopropanol proceeds via dehydration of the alumina catalysts. CuO/Al2O3 and ZnO/Al2O3 surfaces catalyze both the dehydration and dehydrogenation of this alcohol.
Surface and Catalytic Properties of γ-Irradiated Fe2O3/Al2O3 Solids
Authors: El-Shobaky G.A. , Ahmad A.S. , Ghozza A.M. , El-Khouly S.M. 
Published: January 2017

Two specimens of Fe2O3/Al2O3 solids were prepared by impregnating a known mass of finely-powdered Al(OH)3 with calculated amounts of ferric nitrate solutions followed by drying at 120°C and calcination in air at 400°C for 4 h. The mixed solids thus prepared had the nominal molar compositions 0.06Fe2O3/Al2O3 and 0.125Fe2O3/Al2O3 (FeAl-I and FeAl-II). The surface and catalytic properties of various irradiated solids (15–200 Mrad) were studied using nitrogen adsorption at −196°C and catalysis of CO oxidation by O2 at 150–280°C using a static method. The results obtained revealed that γ-irradiation at doses between 15 and 80 Mrad resulted in a progressive decrease (7–22%) in the surface area of the treated solids. Treatment with doses above this limit exerted an opposite effect. γ-Irradiation also resulted in a widening of the pores of the irradiated adsorbents. The catalytic activity of the FeAl-I solid was influenced slightly by γ-rays while the FeAl-II catalyst was significantly modified by this treatment. The reaction rate constant per unit surface area of the catalytic reaction conducted at 280°C over the FeAl-II solid decreased (65%) by exposure to doses up to 120 Mrad, then increased on increasing the dose above this limit. This did not modify the mechanism of the catalytic reaction, but changed the number of catalytically-active sites taking part in chemisorption and catalysis of the CO oxidation reaction without affecting their energetic nature.
Adsorption Characteristics of Coal-Based Activated Carbons. 1. Adsorption of Nitrogen and Carbon Dioxide
Authors: El-Nabarawy Th. , Petro N.Sh. , El-Aziz S.Abd. 
Published: January 2017

Non-activated carbon from coal contains ultrafine pores in which adsorption of nitrogen at 77 K is controlled by activated diffusion. Carbons activated with phosphoric acid or with steam contain a large fraction of microporosity. However, they do not contain ultrafine pores or pore constrictions in which activated diffusion takes place. The BET equation can be applied to calculate the surface area of microporous carbon when the monolayer capacity lies in the relative pressure range 0.05–0.30, the BET areas in such cases being comparable with those obtained from the αs-method. The Dubinin–Radushkevich (D–R) equation is the most suitable for the interpretation of CO2 adsorption at 298 K. Chemical and physical activation starts with new pore creation, further activation being associated with pore widening. Microporosity is more predominant in chemically-activated carbons.
The Effect of the Method of Preparation on the Textural, Acidic and Catalytic Properties of Chromia–Alumina Catalysts
Authors: El-Nabarawy Th. , Khalil L.B. , Youssef A. M. 
Published: January 2017

Pure alumina 'A' and chromia–alumina catalysts containing 25 mol% Cr2O3 (IAC, IIAC and IIIAC) were prepared by impregnation, coprecipitation and coating techniques, respectively. The adsorption of nitrogen at 77 K and of benzene and water vapour at 308 K was determined. The chemisorption of pyridine at 400 K was measured and the surface acidities calculated. The conversion of 2-propanol and cracking of cumene were investigated using the pulse microcatalytic technique. Coating alumina with chromia causes considerable changes in the textural and adsorption properties, impregnation of alumina with chromia leads to smaller variations while coprecipitation gives intermediate changes in textural and adsorption properties. The same was found true for the surface acidities as determined by the chemisorption of pyridine. The dehydration of 2-propanol and cracking of cumene follow first-order kinetics. The dehydration of propanol on alumina and chromia–alumina catalysts is a structure-insensitive reaction independent of the surface area but related to the surface acid density. The cracking of cumene is a structure-sensitive reaction depending on both the extent of the surface and the number of acid sites.
Surface and Catalytic Properties of NiO–Fe2O3 Solids Supported on Al2O3
Authors: El-Shobaky G.A. , Ghozza A.M. , Deraz N.M. 
Published: January 2017

A series of NiO–Fe2O3 catalysts supported on γ-Al2O3 was prepared. The effect of the NiO and Fe2O3 contents and the precalcination temperature on the surface and catalytic properties of the various solids has been investigated. The surface characteristics, viz. SBET, Vp and r, were determined using N2 adsorption conducted at –196°C. The catalytic activities of the various solids were studied using the oxidation of CO by O2 at temperatures in the range between 150°C and 400°C. The prepared solids were preheated in air at various temperatures between 400°C and 1000°C. The results obtained revealed that the SBET values of the different solids decrease progressively on increasing the precalcination temperature above 400°C due to sintering. The specific surface areas were also found to decrease on increasing both the NiO and Fe2O3 contents. The catalytic activities, expressed as reaction rate constant (k) and reaction rate constant per unit area (k), were found to decrease on increasing the precalcination temperature in the range 400–1000°C. Furthermore, the amounts of NiO and Fe2O3 in the different solids modified their catalytic activities in different manners.
Heats of Adsorption of Aliphatic Alcohols on α-Al2O3 at 25–200°C. II. Variations with Chain Length
Authors: Rossi Pier Francesco , Rossi Paola 
Published: January 2017

The adsorption of the first five members of the aliphatic alcohol series on α-Al2O3 has been studied at 25–200°C by means of a heat-flow Calvet microcalorimeter (moderately high temperature). At very low coverage and at 25°C, the values of the differential heats of adsorption of the different alcohols were very high (250–200 kJ/mol) and were apparently independent of the chain length. However, at average coverage, the chain length of the alcohol began to influence both the values and the trends in the differential heats of adsorption of the various alcohols on α-Al2O3. Finally, at high coverage, it was found that the incorporation of each additional –CH2–group in the homologous series led to a decrease in both the integral heat of adsorption and the amount of alcohol adsorbed according to the series MeOH > EtOH > 1-PrOH > 1-BuOH > 1-PeOH. Increasing the temperature led to an increasing dependence of the differential heat on the chain length of the alcohol. In addition, from measurements of the thermokinetic parameters for the heat emission peaks for the adsorbed alcohols, it has been deduced that all five aliphatic alcohols studied adsorb on to an α-Al2O3 surface in an open-chain perpendicular fashion.
Adsorption Equilibria in Carbon/Hydrocarbon/Water Systems
Authors: Eltekova N.A. , Eltekov Yu.A. 
Published: January 2017

Two equations derived from the theory of volume filling of micropores (the DR and DS equations) were used for the description of the liquid-phase adsorption of benzene, toluene and p-xylene from aqueous solution on to two commercial microporous activated carbons. Comparison of the experimental and calculated adsorption isotherms showed good accord between the theoretical and experimental values. The results of this work indicate that the parameters of these equations can be used for modelling a water purification process based on the activated carbons.
Equilibrium Studies for the Adsorption of Dyes on Bagasse Pith
Authors: McKay Gordon , El-Geundi Mohammed , Nassar Mamdouh M. 
Published: January 2017

The adsorption of four dyes on to bagasse pith has been studied. The equilibrium isotherms have been measured and analyzed using the Langmuir, Freundlich and Jossens equations and the experimental data have been compared with the theoretically predicted data. The equilibrium saturation adsorption capacities were 21.7. 22.9. 155.4 and 76.6 mg/g for Telon Blue ANL (Acid Blue 25, CI62055), Erionyl Red RS (Acid Red 114, CI23635), Astrazone Blue FRR (Basic Blue 69) and Maxilon Red BL-N (Basic Red 22, CI11055), respectively. Isotherms were measured at different temperatures and from the data the enthalpies of adsorption were determined to be 11.5, 11.8. 10.3 and 10.7 kJ/mol for Acid Blue 25, Acid Red 114, Basic Blue 60 and Basic Red 22, respectively.
Adsorption of Lower Alcohols from Water Solutions on High Silica Zeolites, Mesoporous MCM-41 and AlPO4-5
Authors: Dahl Ivar M. , Myhrvold Elisabeth , Slagtern Åse , Stöcker Michael 
Published: January 2017

Two dealuminated β-zeolites, zeolite Y and MCM-22 as well as silicalite, MCM-41 and AlPO4-5 have been studied as hydrophobic adsorbents in water solutions. Dealuminated β-zeolite, MCM-22 and silicalite all adsorb alcohols from water solutions. Enhanced adsorption is obtained for alcohols with longer alkyl chains. Adsorption in the practically most interesting 10–80% range of zeolite filling may adequately be described by Langmuir isotherms. The Langmuir adsorption constants are similar for β-zeolite, MCM-22 and silicalite. This indicates that the adsorption is independent of the pore structure for the alcohols tested in this study. The surface silanol density is however important, such that a low SiOH density is required to give lipophilic properties. In line with this, dealuminated zeolite Y, as prepared here, and MCM-41 give only a poor preference for alcohols from water. For the β-zeolite, the dealumination procedure is important for retaining the micropore volume and adsorption capacity of the zeolite. AlPO4-5 shows no potential as an adsorbent for alcohols from water solutions.
Characterization of Maxsorb Activated Carbons and Their Evaluation for Gas Storage
Authors: Manzi S. , Valladares D. , Marchese J. , Zgrablich G. 
Published: January 2017

A series of Maxsorb activated carbons, in powder, pellet and disk form, has been characterized by N2 adsorption, following which CH4 adsorption at high pressures up to 3.5 MPa was studied for the different samples. The evaluation of these materials for gas storage shows very promising behaviour for Maxsorb disks with a storage capacity of 150 volumes of gas at STP per container volume at 3.5 MPa.
Effect of Li2O Doping on the Surface and Catalytic Properties of the Fe2O3–NiO/Al2O3 System
Authors: El-Shobaky G.A. , Ghozza A.M. , Deraz N.M. 
Published: January 2017

Ferric–nickel/aluminium mixed oxide solids have the formula Fe2O3–0.42NiO/Al2O3 were treated with Li2O (0.75–3 mol%) and heated in air for 4 h at 500°C and 800°C, respectively. The effects of this treatment on the surface characteristics of these solids and their catalytic properties in relation to CO oxidation by O2 have been investigated. The results reveal that Li2O doping at 0.75 mol% concentration resulted in an increase of 24% and 18%, respectively, in the value of the specific surface areas, SBET, of the solids precalcined at 500°C and 800°C, while the addition of 3 mol% Li2O led to a slight decrease of ca. 10% in the SBET value of the same solids. In contrast, irrespective of whether the doping process involved solids precalcined at 500°C or 800°C, a significant decrease of 37% and 78%, respectively, was observed in the catalytic activity of these materials. This decrease in catalytic activity was not accompanied by any appreciable change in the magnitude of the activation energy for the catalytic reaction, i.e. Li2O doping brings about a decrease in the concentration of catalytically active sites without changing their energetic nature.
Methanation Activity in Relation to the Textural and Catalytic Parameters of Ni/Al2O3 Catalysts
Authors: Samra S.E. , El-Hakam S.A. , Youssef A.M. 
Published: January 2017

A range of NiO/Al2O3, solids (4.0–12.0 wt% Ni) was prepared by the impregnation technique. The textural properties of these solids were determined from nitrogen adsorption measurements at 77 K. Reduction of the solids with hydrogen was carried out 650, 675, 700 and 725 K. Some catalytic parameters for these reduced materials were determined from studies of the adsorption of hydrogen at 400 K. The methanation of carbon monoxide over these reduced materials used as catalysts was followed between 550 K and 600 K using a steady-state flow reactor. The surface area of the NiO/Al2O3 solids decreased and their mean pore radius increased with increasing content of NiO. Increasing the temperature employed for their reduction led to increased diffusion of Ni atoms to the surface with a consequent increase in their catalytic activity. A direct relationship was found between % methanation and the surface area of the reduced catalytic material expressed as m2/g (catalyst).
Changes in Textural Properties of Precalcined Silicas Induced by Adsorption of Some Low Molecular Weight Polymers
Authors: Youssef A.M. , El-Nabarawy Th. 
Published: January 2017

The adsorption of low molecular weight poly(methacrylic acid n-butyl ester) (PBMA) and poly(ethylene glycol) (PEG) on silicas precalcined at 673–1473 K was studied. The changes brought about in the textural properties (total surface area and pore volume distribution) by the adsorption of these polymers were determined. Adsorption of PBMA and PEG resulted in a decrease in the specific surface area as determined by nitrogen adsorption at 77 K since the fraction of the surface located in the micropores was covered by the polymer. Adsorption of polymers reduced the water adsorption capacities of the silicas, particularly those precalcined at ≤ 1073 K, as a result of a decrease in the number of surface OH groups. Polymer adsorption on the precalcined silicas made the contribution of mesopores more prominent, the changes in the textural properties of the silicas depending on the stage at which the polymer was added during the course of silica preparation.
Prevention of Sapheno-Femoral and Sapheno-Popliteal Recurrence of Varicose Veins by Forming a Partition to Contain Neovascularization
Authors: Glass G. M. 
Published: January 2017

Objective: To test the hypothesis that sapheno-femoral recurrence of varicose veins may be prevented by containment of neovascularization. Design: Prospective minimum 4-year follow-up by surgical exploration and morphological examination of recurrent vessels in all limbs with clinical or phlebographic evidence of sapheno-femoral recurrence. Setting: Varicose vein clinic of a teaching hospital. Interventions: Sapheno-femoral ligation and multiple ligation (group 1); sapheno-femoral ligation, interposition of cribriform fascia and multiple ligation (group 2); sapheno-femoral ligation, interposition of artificial implant and stripping (group 3). Main outcome measures: Incidence of sapheno-femoral recurrence. Results: The incidence of sapheno-femoral recurrence through neovascularization was lower ( p < 0.001) in groups 2 and 3 after containment of neovascularization at the sapheno-femoral junction by cribriform fascia or artificial implant than in group 1 after ligation alone (3% and 1% vs 25%, respectively). The incidence of recurrent or persistent varices distal to the groin was lower ( p < 0.001) after stripping (group 3, 57%) than after multiple ligation (group 1, 93%; group 2, 81%). Conclusions: Sapheno-femoral ligation, interposition of cribriform fascia or artificial implant at the sapheno-femoral junction, and stripping is a more effective treatment of varicose veins than sapheno-femoral ligation and multiple ligation.
Venous Leg Ulcers: Is Pain a Problem?
Authors: Noonan L. , Burge S. M. 
Published: January 2017

Objective: To employ standardized techniques to measure and characterize the pain associated with leg ulcers of defined causes. Methods: Patients attending leg ulcer clinics were interviewed by one research nurse using a structured questionnaire. Ulcers were classified as venous, arterial or mixed depending on the clinical assessment and ankle–brachial systolic pressure index. Pain was assessed objectively using two validated instruments for scoring pain: a verbal rating scale and a pain-intensity visual analogue scale. The significance of the observations was tested using either the Mann-Whitney U-test (unpaired observations) or the Wilcoxon signed-rank test (paired observations). A profile of the quality of pain was obtained using the short-form McGill Pain Questionnaire (SF-MPQ). Quality of life was assessed using the COOP Chart System. Patients: We assessed 38 patients with venous ulcers, three patients with mixed arterial/venous ulceration and 10 patients with arterial disease. Main outcome measures: Pain scores on verbal rating scales and visual analogue scales. Results: Venous leg ulcers are painful. Although pain scores are greater in arterial ulcers, most patients with venous ulceration suffer at least moderate pain. Night pain disturbed sleep in 73% of all patients and pain affected mood in more than 50%. Dressing changes exacerbated pain. Conclusions: Pain reduces the quality of life in most patients with leg ulcers. Pain control is an essential consideration in all patients with leg ulcers.
Prospective Comparison of Healing Rates and Therapy Costs for Conventional and Four-Layer High-Compression Bandaging Treatments of Venous Leg Ulcers
Authors: Taylor A. D. , Taylor R. J. , Marcuson R. W. 
Published: January 2017

Objective: To compare healing rates and associated treatment costs of four-layer high-compression bandaging (HCB) and conventional management (CM), as available on FP10, in the treatment of venous leg ulcers. Design: Randomized prospective study in which patients were allocated to one of two treatment groups. Setting: Hospital-based leg ulcer service and community. Patients: Thirty-six patients presenting with venous leg ulcers (30 compilers): 16 patients (nine female) in the HCB group and 14 patients (10 female) in the CM group. Interventions: A 12-week treatment period with either a four-layer HCB regime or CM. Main outcome measures: The significance of the difference between the number of ulcers healed, and associated treatment costs, was investigated using the Mann–Whitney U-test and survival analysis. Results: Four-layer HCB achieves a significantly ( p = 0.003) higher healing rate of ulcers (75% of patients versus 21%) over a 12-week period. Weekly treatment costs for the four-layer therapy was significantly less than that of CM (mean difference in cost = £6.45, 95% CI = £1.22–11.68; p = 0.042). Conclusion: It is more efficacious and economical for nurse specialists to treat patients presenting with leg ulcers with a four-layer HCB regime than for district nurses to carry out the standard palliative treatments available on GP prescription form FP10.
Changes in Interface Pressure under Elastic and Short-Stretch Bandages during Posture Changes and Exercise
Authors: Hirai M. 
Published: January 2017

Objective: To evaluate the pressure under short-stretch and elastic bandages. Design: Prospective study in 20 healthy volunteers, comparing the two different kinds of bandages. Setting: Department of Surgery, Aichi Prefectural College of Nursing, Nagoya, Japan. Main outcome measures: Pressure measurements were made beneath the bandages with different initial pressures of 10, 20, 30, 40, 50, 60, and 70 mmHg, during supine resting, standing, tip-toe exercise and walking. Results: Short-stretch bandages showed a significant increase in pressure during standing and exercise at lower initial pressures compared with elastic bandages. In analysing the pressure waveform during tip-toe exercise and walking, a significantly greater pressure difference between muscle contraction and relaxation was noted for short-stretch bandages compared with elastic bandages at any initial pressures. Conclusions: Short-stretch bandages produce a higher working pressure and a larger pressure difference during exercise. However, the effect depends on the initial pressures at the time of application. In clinical practice, prevention of a decrease in pressure with time and uniform application of bandages are important.