bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface and Catalytic Properties of the CuO/Al2O3 System as Influenced by Treating with Trace Amounts of MoO3
Authors: Mokhtar M. 
Published: October 2003

A CuO/Al2O3 solid containing 0.2 mol% CuO (0.2CuO/Al2O3) and three MoO3-doped variants of this material were all prepared via the wet impregnation method, the amount of dopant added to the CuO/Al2O3 solid being 0.25, 1.0 or 2.0 mol% MoO3, respectively. All the samples prepared were heated in air to 350, 450 or 600°C, respectively, before being cooled to room temperature and stored. X-Ray studies of these materials showed that the undoped (pure) solid calcined at 350°C exhibited all the diffractions lines associated with the AlO(OH) and CuO phases with an excellent degree of crystallinity. Doping the pure solid resulted in the effective progressive decrease in the degree of crystallinity of both the above-mentioned phases to an extent proportional to the amount of dopant added. Increasing the calcination temperature of the pure and doped solids to 650°C led to a significant decrease in the degree of ordering of CuO due to the formation of poorly crystalline γ-Al2O3 having a much better dispersion power relative to AlO(OH). The specific surface areas of the various samples were found to decrease progressively as the amount of dopant added was increased, especially for samples calcined at 650°C. Increasing the calcination temperature of the pure sample within the range 350–650°C led to a small increase in their catalytic activities in H2O2 decomposition. In contrast, MoO3 treatment followed by calcination of the resulting materials in the range 350–650°C resulted in a significant increase in their catalytic activities in the same catalytic reaction. The maximum increase in the catalytic activity at 30°C attained values of 720%, 735% and 976% for the doped solids calcined at 350, 450 and 650°C, respectively. In contrast, however, such doping brought about a progressive measurable decrease in the catalytic activity of the treated solids towards CO oxidation by O2 when this latter reaction was conducted over the temperature range 150–250°C.
Adsorption of Polydisperse Polyvinyl Alcohol Molecules on the Surface of Activated Carbons
Authors: Barkauskas J. , Vinslovaite A. 
Published: October 2003

The adsorption of polyvinyl alcohol (PVA) on activated carbons was studied in aqueous solutions. Each batch of activated carbon produced was obtained via a definite number of technological operations using wood as the raw material. The adsorption process was studied using a gel chromatography technique with potentiometric titrations being employed for evaluating the chemical composition of the activated carbons produced. The data obtained from the various activated carbon samples were compared to ascertain the adsorption mechanism. It was concluded that water molecules had a limited influence on the competitive process of polymer adsorption. A rather pronounced negative correlation between the number of phenol functional groups and PVA adsorption capacity was observed, indicating that these groups hindered the adsorption process. Assumptions concerning the role of phenol functional groups were made, taking into account not only the surface heterogeneity but also changes in the electron density of the graphene layers in the carbon substrate.
Use of NSAIDs for the Chemoprevention of Colorectal Cancer
Authors: Herendeen Jill M , Lindley Celeste 
Published: October 2003

OBJECTIVE: To discuss the role of nonsteroidal antiinflammatory drugs (NSAIDs) in the chemoprevention of colorectal cancer. DATA SOURCES: A MEDLINE search (1966–May 2003) was performed to identify key literature. Search items included, but were not limited to, NSAIDs, colorectal cancer, chemoprevention, cyclooxygenase-2 (COX-2)–specific inhibitors, and familial adenomatous polyposis (FAP). STUDY SELECTION AND DATA EXTRACTION: The search included experimental (in vitro and animal models) and clinical studies evaluating the use of NSAIDs for the chemoprevention of colorectal cancer. The MEDLINE search was supplemented by references from selected articles. DATA SYNTHESIS: Numerous experimental, epidemiologic, and clinical studies suggest that NSAIDs have promise as anticancer agents. The mechanism by which NSAIDs lead to decreased colon carcinogenesis is not fully understood, but may involve restoration of apoptosis and inhibition of prostaglandin-mediated angiogenesis. Compelling evidence from many observational studies has consistently documented a 40–50% reduction in the risk of adenomatous polyps, colorectal cancer incidence, and mortality in patients using NSAIDs. Recent randomized, controlled trials have demonstrated a benefit with aspirin in reducing the rate of development of new or recurrent adenomas in high-risk patients. In addition, randomized studies using sulindac and celecoxib in patients with FAP have documented significant regression of existing adenomatous polyps. CONCLUSIONS: Inhibition of COX-2 is an example of a targeted approach to the chemoprevention of colorectal cancer. However, controversy exists about the safety, efficacy, and optimal treatment regimen of NSAIDs as long-term chemopreventive agents in the general population. Ongoing studies in high-risk patients with both selective and nonselective COX inhibitors will provide important information in the area of colorectal chemoprevention, but clinical trials' use of adenomas as surrogate markers for chemoprevention trials makes their application to the general population limited.
Enteric-Coated Mycophenolate Sodium
Authors: Gabardi Steven , Tran Jennifer L , Clarkson Michael R 
Published: October 2003

OBJECTIVE:To review the pharmacology, pharmacokinetics, efficacy, and safety of mycophenolate sodium.DATA SOURCES:Primary literature was obtained via a MEDLINE search (1966–June 2003). Abstracts were obtained from the manufacturer and included in the analysis.STUDY SELECTION AND DATA EXTRACTION:All studies and abstracts evaluating mycophenolate sodium in solid organ transplantation were considered for inclusion. English-language studies and abstracts were selected for inclusion, but were limited to those consisting of human subjects.DATA SYNTHESIS:Mycophenolate sodium, a mycophenolic acid prodrug, is an inhibitor of T-lymphocyte proliferation. Mycophenolic acid reduces the incidence of acute rejection in renal transplantation. Mycophenolate sodium is enteric coated and has been suggested as a potential method to reduce the gastrointestinal adverse events seen with mycophenolate mofetil. Both mycophenolate mofetil and mycophenolate sodium have been shown to be therapeutically equivalent at decreasing the incidence of allograft rejection and loss. The frequency of adverse events is similar between both compounds, with the most common events being diarrhea and leukopenia.CONCLUSIONS:Mycophenolate sodium is effective in preventing acute rejection in renal transplant recipients. At doses of 720 mg twice daily, the efficacy and safety profiles are similar to those of mycophenolate mofetil 1000 mg twice daily. Mycophenolate sodium has been approved in Switzerland; approval in the US is pending.
Levels of measurement and analysis issues in organizational citizenship behaviour research
Authors: Schnake Mel E. , Dumler Michael P. 
Published: October 2003

The majority of work in organizational behaviour has been conducted at the individual level of theory, measurement and analysis. While the field of organizational behaviour may be viewed as largely mixed‐level, incorporating individual, group and organizational‐level phenomena, relatively few group‐level and mixed‐level theories with corresponding levels of research exist. This is particularly problematic for organizational citizenship behaviour (OCB) research, since OCB is theorized to exist at multiple levels. Several individual‐level and group‐level antecedents affect OCB, but it is OCB in the aggregate (i.e. group and organizational level) which impacts organizational effectiveness, which is another organizational‐level phenomenon.A brief review of group‐level and mixed‐level research methodology is presented and these methods are then applied to a burgeoning area of organizational behaviour research, one which is inherently group and mixed‐level, organizational citizenship behaviour (OCB). Implications of the different levels of measurement and analysis for OCB theory development and testing are discussed.
Molybdän‐ und Wolframimidoalkylidenkomplexe als effiziente Olefinmetathesekatalysatoren
Authors: Schrock Richard R. , Hoveyda Amir H. 
Published: October 2003

AbstractDie katalytische Olefinmetathese hat sich schnell zu einer der am häufigsten eingesetzten Transformationen der modernen chemischen Synthese entwickelt. Ein Klasse von Katalysatoren, die den Weg zu dieser bedeutenden Entwicklung wiesen, sind die hochoxidierten Alkylidenkomplexe des Molybdäns. Dieser Aufsatz umreißt entscheidende Beobachtungen, die zur Entdeckung und Entwicklung von Molybdän‐ und Wolfram‐Metathesekatalysatoren führten. Schwerpunktmäßig beschrieben wird der Einsatz von Molybdänkatalysatoren in der Synthese biologisch relevanter Verbindungen und die Verwendung von chiralen Molybdänkomplexen zur enantioselektiven Synthese. Derartige hocheffiziente Katalysatoren eröffnen einen einzigartigen Zugang zu Materialien von außergewöhnlicher Enantiomerenreinheit, häufig unter Vermeidung von Lösungsmittelabfällen.
Magnetic Control of Electrocatalytic and Bioelectrocatalytic Processes
Authors: Willner Itamar , Katz Eugenii 
Published: October 2003

AbstractBioelectronics is a rapidly progressing interdisciplinary research field that has important implications for the development of biosensors, biofuel cells, biomaterial‐based computers, and bioelectronic devices. Magneto‐controlled molecular electronics and bioelectronics are new topics that examine the effect of an external magnetic field on electrocatalytic and bioelectrocatalytic processes of functionalized magnetic particles associated with electrodes. In this article we describe the progress in the developments of magneto‐switchable electrocatalytic and bioelectrocatalytic transformations, and the effects of the rotation of the magnetic particles on the electrocatalytic and bioelectrocatalytic processes are discussed. Finally, the implications of the results on the development of biosensors, amplified immunosensors, and DNA sensors are described.
Molybdenum and Tungsten Imido Alkylidene Complexes as Efficient Olefin‐Metathesis Catalysts
Authors: Schrock Richard R. , Hoveyda Amir H. 
Published: October 2003

AbstractCatalytic olefin metathesis has quickly emerged as one of the most often‐used transformations in modern chemical synthesis. One class of catalysts that has led the way to this significant development are the high‐oxidation‐state alkylidene complexes of molybdenum. In this review key observations that resulted in the discovery and development of molybdenum‐ and tungsten‐based metathesis catalysts are outlined. An account of the utility of molybdenum catalysts in the synthesis of biologically significant molecules is provided as well. Another focus of the review is the use of chiral molybdenum complexes for enantioselective synthesis. These highly efficient catalysts provide unique access to materials of exceptional enantiomeric purity and often without generating solvent waste.
Children's rights in schools: what do teachers know?
Authors: Shumba Almon 
Published: October 2003

AbstractThe human rights of children are fundamental international human rights that protect all children against abuse by adults and caregivers as enshrined in the United Nations Convention on the Rights of the Child. This study examines teachers' and teacher trainees' knowledge of children's rights as enshrined in the United Nations Convention on the Rights of the Child (United Nations General Assembly, 1989), the Public Service (Disciplinary) Regulations (Statutory Instrument 65 of the Constitution of Zimbabwe, 1992) and the Secretary of Education and Culture Circular P35 of 3 May 1993 on the administration of corporal punishment by teachers in Zimbabwean primary schools. Data were collected using the Teacher and the Teacher Trainees Questionnaires on 300 primary school teachers and 150 teacher trainees, respectively, in Masvingo Province. Teacher trainees used in this study were attached to experienced primary school teachers during their teaching practice. The study found that the majority of teachers (76.3%) were exposed to the Public Service (Disciplinary) Regulations during their teacher education training. On the other hand, the majority of teacher trainees (60.0%) were not exposed to these Regulations during their training. The Public Service (Disciplinary) Regulations are used to charge teachers who violate children's rights within the school. The majority of teachers (59.3%) feel they are useful, while the majority of teacher trainees (60.0%) feel they are outdated and need to be changed. On the other hand, the majority of teacher trainees (55.3%) indicated that they were exposed to the United Nations Convention on the Rights of the Child or the African Charter on the Rights and Welfare of the Child (OAU Doc. CAB/LEG/24.9/49, 1990), while the majority of teachers (56.7%) were not exposed to either of these during their teacher education training. The study also found that the majority of teacher trainees (63.3%) were not exposed to the Secretary of Education and Culture Circular P35 on corporal punishment by teachers within schools during their teaching practice. It is clear from the ﬁndings that the teacher education curriculum needs to be revised to take account of current trends and contemporary issues in education in the new millennium. Therefore, there is a need for the Ministry of Education, Sport and Culture to conduct in‐service programmes for teachers who are not familiar with local and international laws concerning the protection of children against child abuse within the school. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and characterization of hexagonal ferrites BaFe12‐2xZnxTixO19 (0 ≤ x ≤ 2) by thermal decomposition of freeze‐dried precursors
Authors: Rösler S. , Wartewig P. , Langbein H. 
Published: October 2003

AbstractSubstituted barium hexaferrites, BaFe12‐2xZnxTixO19 (0 ≤ x ≤ 2), have been synthesized by thermal decomposition of freeze‐dried acetate precursors. Decomposition and phase formation were investigated by means of thermal analysis, XRD and IR spectroscopy. The initially amorphous decomposed precursor reacts to the substituted hexaferrite via a spinel‐like maghemite (γ‐Fe2O3) and Zn/Ti containing spinel ferrites. The synthesis method allows a decrease of the reaction temperature and time, necessary for producing a single phase hexaferrite. At relative low reaction temperatures, the substitution rate x shows remarkable differences at different iron sublattices. For x ≤ 0,8 this selective substitution results in an increase of magnetization as x grows. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on rapid growth of highly‐deuterated DKDP crystals
Authors: Wang S. L. , Gao Z. S. , Fu Y. J. , Duan A. D. , Sun X. , Fang C. S. , Wang X. Q. 
Published: October 2003

AbstractHighly‐deuterated potassium dihydrogen phosphate (DKDP) crystals were grown rapidly from point seeds under high supersaturation in a temperature range of 40‐60 °C. The growth rate was about 1‐2 order of magnitude higher than that of the traditional temperature reduction method. It was found that highly pure raw materials, overheating at high temperature, ultrafine filtration and supersaturation stability were needed to keep the solution from spontaneous nucleation at high overcooling. The effect of growth conditions on pyramid faces was different from that of prismatic faces. The tetragonal to monoclinic phase solubility transition scarcely occurred in our experiments even though the overcooling of monoclinic phase was as high as 10 °C in some cases. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, X‐ray data, and Hall effect measurements of Li‐doped Tl‐Ba‐Ca‐Cu‐O superconductor
Authors: Kayed T. S. 
Published: October 2003

AbstractLithium‐doped Tl‐based superconductor was prepared by adding an amount of 0.3 mol.% to the Tl1.8Ba2Ca2.2Cu3Ox compound. The usual solid‐state reaction method has been applied under optimum conditions. The x‐ray data of the sample show a tetragonal structure with a high ratio of Tl‐2223 superconducting phase. The sample showed a transition at 125 K and the zero resistance was observed at 117 K. Longitudinal (transport) and transverse (Hall) resistivities were measured at different temperatures under different magnetic fields and the data were interpreted. A positive Hall coefficient was observed at normal state and a sign reversal appears at temperatures lower than the critical temperature. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Triple axis diffractometric investigations of the microstructure of thin AlxGa1‐xN epitaxial films
Authors: Zielinska‐Rohozinska E. , Kowalska M. , Pakuła K. 
Published: October 2003

AbstractAlxGa1‐xN/GaN (Si doped or undoped) with the Al content in the composition range of 0.046 ≤ x ≤ 0.164 grown on the c sapphire face by atmospheric pressure MOCVD method were studied by high resolution x‐ray diffraction including symmetrical and asymmetrical ω/2θ scans and reciprocal space maps. A high sensitivity to small inhomogeneities of the layer thickness and lattice mismatch between AlGaN and GaN is reported, recognised as changes in the interference pattern of the diffraction peak observed across the sample. They are very well correlated with optical properties derived from independent photoreflectivity measurements. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Changes of Auger parameter in doped SnO2 powders
Authors: Dobler D. , Oswald S. , Behr G. , Werner J. , Wetzig K. 
Published: October 2003

AbstractDoped SnO2 powders were studied using X‐ray photoelectron spectroscopy (XPS). The Auger parameters (AP) for Sn and different doping elements were determined. A dependence of the Auger parameter on the doping element and doping concentration was observed. The detected shift could be correlated with the electrical properties of the studied samples as well as with the formation of a second phase and a segregation layer at the surface. Bulk doping with elements having a valency greater than 4 (Sb), leads to an increase of the electron density connected with a decrease of resistivity. In this case we can observe the shift of the AP to higher values. This means that the relaxation of the electron holes is energetically more favourable for Sb doped than for pure tin oxide. On the other side, doping with elements the valency of which is less than 4 (In) on tin sites leads to a decrease in electron density and causes an increase of resistivity of the material. We observe in this case a shift of the AP to lower values due to lower relaxation energy. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Poole‐Frenkel electrical conduction in europium oxide films deposited on Si(100)
Authors: Dakhel A. A. 
Published: October 2003

AbstractThin Eu2O3 films were prepared on Si (P) substrates to form MOS devices. The oxide crystal structure was determined by X‐ray diffraction (XRD). The electrical transport properties of the devices with amorphous and crystalline Eu oxide were investigated. The current‐voltage and current‐temperature characteristics suggest a Poole‐Frenkel (PF) type mechanism of carrier transport through the device when the applied field is more than 105 V/cm. A deviation from PF leakage current course was found and attributed to the current carrier trapping. We have also observed that, the dielectric spectra of MOS structure are different when the insulator is an amorphous or crystalline thin film. From which we calculate the relaxation time (τ) of the interface (insulator/semiconductor) dipoles. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of thermally evaporated thin CdO films
Authors: Dakhel A. A. , Henari F. Z. 
Published: October 2003

AbstractCadmium Oxide films have been prepared by vacuum evaporation method on a glass substrate at room temperature. Detailed structural, optical, and electrical properties of the films are presented at different annealing temperatures. The crystal structure of the samples was studied by X‐ ray diffraction. The spectral absorption coefficient of the CdO film at the fundamental absorption region (450‐650nm) was determined using the spectral data of transmittance. The direct and indirect band gap energies were determined and found to be 2.33 eV and 1.95 eV respectively. The third order optical nonlinearities χ(3) of CdO films has been measured used the z‐can technique. The real and imaginary parts of χ(3) have been measured at 514 nm and found to be 1.7x10‐3 esu and 3.0x10‐3 esu, respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical and microhardness studies of semiorganic nonlinear optical material: L‐ histidine tetrafluoroborate
Authors: Ramajothui Jayaraman , Dhanuskodi Sivasubramanian 
Published: October 2003

AbstractL‐histidine tetrafluoroborate (L‐HFB) a semiorganic nonlinear optical material has been synthesized in aqueous solution at 50°C and characterized by FT‐IR and FT‐Raman spectroscopy studies. The solubility was determined in different solvents such as water, methanol and water mixture of methanol. The single crystals with dimensions 15x12x3 mm3 were grown by slow evaporation method within four weeks with approximate growth rate of 0.25 mm/day. The grown crystals have been subjected to single crystal X‐ray diffraction studies to determine the unit cell dimensions and morphology. The Kurtz powder second harmonic generation test shows that the compound is a potential candidate for frequency conversion. The refractive index has been measured using He‐Ne laser. The microhardness test was carried out and the load dependence hardness was observed. The material has a wide transparency in the entire visible region. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, crystal and molecular structure of trans‐bis(2‐pyridinepropanol)bis(saccharinato)nickel(II)
Authors: Yilmaz V. T. , Hamamci S. , Thöne C. 
Published: October 2003

AbstractTrans‐bis(2‐pyridinepropanol)bis(saccharinato)nickel(II), [Ni(sac)2(pypr)2], where sac and pypr are the saccharinate anion and the 2‐pyridinepropanol molecule, respectively, crystallizes in the triclinic space group P$\bar 1$ (No. 2) with a = 8.1981(8), b = 9.9680(10), c = 10.4956(10) Å, α = 90.740(3)° β = 108.142(3)°, γ = 111.025(3)°, Z = 1, V = 1.537 Å3. The structure of the nickel(II) complex consists of neutral molecules in which the nickel(II) ion sits on a center of symmetry and is octahedrally coordinated by two sac ligands, and two neutral pypr ligands. The pypr acts as a bidentate N‐ and O‐donor ligand forming a seven‐membered chelate ring, while sac behaves as a monodentate O‐donor ligand via the carbonyl O atom. The Ni‐N bond distance is 2.1016(15) Å, whereas the Ni‐Opypr and Ni‐Osac bond distances are 2.1280(12) and 2.0792(11) Å, respectively. The individual molecules are held together with a strong hydrogen bond between the hydroxyl O atom of pypr and N atom of sac and the C‐H…O type weak hydrogen bonds between some ring hydrogen atoms of pypr and sac, and the carbonyl and sulfonyl O atoms of sac in the neighbouring molecules. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)