bluuebunny/crossref_metadata_2025_split huggingface dataset:
The heterogeneous decomposition of ozone on atmospheric mineral dust surrogates at ambient temperature
Authors: Karagulian Federico , Rossi Michel J. 
Published: April 2006

AbstractThe rate of uptake of ozone on various mineral dust surrogates, expressed as uptake coefficient γ, has been studied employing a Knudsen flow reactor. Experiments were performed at T = 298 ± 2 K on substrates of kaolinite, CaCO3, natural limestone, Saharan dust, and Arizona test dust. Initially, the uptake coefficients have been calculated on the basis of the geometric surface area of the powder samples. Both initial and steady‐state uptake coefficients γ0 and γss were found very similar for all the examined substrates. In addition, additional uptake experiments on marble sample have shown that γ0 and γss may be overestimated between a factor of 50 and 100, respectively. Based on these considerations, we proposed initial and steady‐state uptake values of the order of 10−4 and 10−5, respectively. On kaolinite, the uptake coefficient decreased with increasing O3 residence time τg thus indicating a complex mechanism. In contrast, γ decreased and became independent of τg at long residence time after long exposure to O3. For all uptake experiments the disappearance of O3 was accompanied by the formation of O2. The different mineral dust surrogates may be more accurately distinguished by their time‐dependent O2 yield r(t) rather than the magnitude of γ. The heterogeneous reaction of O3 on mineral dust has been found to be noncatalytic and of limited importance in the atmosphere. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 407–419, 2006
Clay‐PMMA Nanocomposites by Photoinitiated Radical Polymerization Using Intercalated Phenacyl Pyridinium Salt Initiators
Authors: Nese Alper , Sen Sinan , Tasdelen Mehmet Atilla , Nugay Nihan , Yagci Yusuf 
Published: April 2006

AbstractSummary: In situ synthesis of poly(methyl methacrylate) (PMMA) nanocomposites by photopolymerization using organophilic montmorillonite (MMT) as the layered clay is reported. MMT clay was ion exchanged with N‐phenacyl, N,N‐dimethylanilinium hexafluoro phosphate (PDA) which acts as both suitable intercalant‐ and photo‐initiator. These modified clays were then dispersed in methyl methacrylate (MMA) monomer in different loading degrees to carry out the in situ photopolymerization. Intercalation ability of the photoinitiator and exfoliated nanocomposite structure were evidenced by both X‐ray diffraction (XRD) spectroscopy and transmission electron microscopy (TEM). Thermal properties and morphologies of the resultant nanocomposites were also studied.Schematic representation of clay‐PMMA nanocomposites by photoinitiated radical polymerization.imageSchematic representation of clay‐PMMA nanocomposites by photoinitiated radical polymerization.
A Novel Strategy to Synthesize Double Comb‐Shaped Water Soluble Copolymer by RAFT Polymerization
Authors: Han De‐Hui , Pan Cai‐Yuan 
Published: April 2006

AbstractSummary: A double comb‐shaped water soluble copolymer, poly[poly(ethylene oxide) methyl ether methacrylate]‐block‐poly(N‐isopropylacrylamide)‐block‐poly[poly (ethylene oxide) methyl ether methacrylate], abbreviated as [P(MA‐MPEO)‐block‐PNIPAM‐block‐P(MA‐MPEO)], with a controlled molecular weight and narrow polydispersity was successively synthesized using a macromonomer technique. The 60Co γ irradiation polymerization of MA‐MPEO in the presence of dibenzyl trithiocarbonate (DBTTC) at room temperature afforded a polymer, P(MA‐MPEO)‐SC(S)S‐P(MA‐MPEO), which was subsequently used as a macro RAFT agent in the RAFT polymerization of N‐isopropylacrylamide, and water soluble double comb‐shaped copolymers, P(MA‐MPEO)‐block‐PNIPAM‐block‐P(MA‐MPEO), were successfully obtained.Structure of the double comb‐shaped copolymer.imageStructure of the double comb‐shaped copolymer.
The Role of Oxidation in the Migration Mechanism of Layered Silicate in Poly(propylene) Nanocomposites
Authors: Zammarano Mauro , Gilman Jeffrey W. , Nyden Marc , Pearce Eli M. , Lewin Menachem 
Published: April 2006

AbstractSummary: Evidence of clay migration from the core to the surface of poly(propylene)/montmorillonite nanocomposites is provided. A three‐ to fivefold increase in the clay concentration of the surface is obtained during isothermal heating in oxidative atmosphere. The mechanism of migration is investigated by means of attenuated total reflectance Fourier transform infrared spectrometry. It is shown that oxygen plays a fundamental role in the migration mechanism.ρSi versus c for the annealed samples.magnified imageρSi versus c for the annealed samples.
The Local and Collective Mobility in Polymer Chains and Networks with Included Rigid Particles Elastically Connected with the Network
Authors: Gotlib Yuli Ya. , Torchinskii Isaak A. , Toshchevikov Vladimir P. , Shevelev Vladimir A. 
Published: April 2006

AbstractSummary: The theory of molecular mobility of a polymer network with included rod‐like particles is developed. The case is considered when the length of rods is comparable or greater than the average distance between neighboring cross‐links of the primary network. The long‐scale dynamics of the network is described by means of a regular cubic “coarse‐grained” model. The junctions of this model describe the great network fragments (domains) the sizes of which are near to the average distance between neighboring rods.The quasi‐elastic interactions between rods and network fragments lead to a broad relaxation spectrum for included rods as compared with free rods which are characterized by a single relaxation time of rotational diffusion. The frequency dependence of the dielectric loss factor of included rods is calculated for rods with permanent dipole moments directed parallel to the long axes of the rods chaotically distributed in the network. The frequency dependence of dynamic modulus of a polymer network with included rods is obtained. The increment in the dynamic modulus of the relatively short network motions (smaller than the distance between rods) also is taken into account. The broad relaxation spectrum of included rods leads to appearance of several maximums on the frequency dependences of both the dielectric loss factor and dynamical modulus.
Synthesis and Characterization of Deuterated Glycidyl Azide Polymer (GAP)
Authors: Ringuette Sophie , Dubois Charles , Stowe Robert A. , Charlet Gérard 
Published: April 2006

AbstractDecomposition mechanisms of propellants are of great interest in understanding performance issues of chemical propulsion systems. The characterization of physico‐chemical properties of glycidyl azide polymer (GAP), specifically deuterated analogs, was investigated in this study. The purpose of this new approach is to identify the key steps in thermal decomposition mechanism of GAP. The present work shows that the use of deuterated GAP is a good method to study the decomposition pathway of energetic polymers. The polymerization process was successful, but was nevertheless affected by the use of the isotopic monomer since the resulting polymers had a slightly lower molecular weight. The chemical characterization of the deuterated GAPs by NMR and FTIR confirm the structure of these new polymers. The TGA analyses show a larger weight loss during the first step of decomposition for labeled GAP suggesting that molecular nitrogen and heavier compounds are produced simultaneously.
Growth by LPCVD, crystallization and characterization of SiGe nanoparticles for nanoelectronic devices
Authors: Ortiz M. I. , Sangrador J. , Rodríguez A. , Rodríguez T. , Kling A. , Franco N. , Barradas N. P. , Ballesteros C. 
Published: April 2006

AbstractAmorphous SiGe nanoparticles embedded in an oxide matrix, with controlled composition, diameter of a few nm, located in the same plane and with an areal density above 1012 cm–2 have been deposited by Low Pressure Chemical Vapour Deposition in a single run using a conventional hot wall reactor. The deposited nanoparticles were crystallized by Rapid Thermal Annealing. X‐ray Reflectometry and Rutherford Backscattering Spectrometry, with models developed for these purposes, have been tested as fast and reliable analytical tools to determine the composition, size and areal density of the nanoparticles. Transmission Electron Microscopy has been used to validate the results and to study the nanoparticle crystallization. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of magnetic field on spin blockade lifting of weakly coupled quantum dots
Authors: Iñarrea Jesús , Platero Gloria , MacDonald Allan H. 
Published: April 2006

AbstractWe study the electronic transport through a double quantum dot subjected to spin blockade. Experiments of current rectification by Pauli exclusion principle in double quantum dots are reproduced with our model based in the density matrix formalism. Our calculations include a self‐consistent description of the electron and nuclei spin dynamics within the double dot which indicates that the current leakage experimentally observed in the spin‐blockade region of the current–voltage curve, occurs due to spin‐flip processes induced by hyperfine interaction between the electrons and nuclei spins. We show as well how a magnetic field applied to the sample, in the direction of the current, allows excited states to participate in the electronic current and removes spin blockade. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First principles calculation of isolated intermediate bands formation in a transition metal‐doped chalcopyrite‐type semiconductor
Authors: Palacios P. , Sánchez K. , Conesa J. C. , Wahnón P. 
Published: April 2006

AbstractDensity Functional Theory (DFT) calculations at the GGA level have been carried out for Ti‐substituted chalcopyrite‐type CuGaS2, as it might constitute an intermediate band material of the kind that has been proposed to lead to enhanced efficiency photovoltaic cells. According to these calculations an intermediate band appears when Ti substitutes Ga at a 25% level in this structure, resulting in a magnetic half‐metallic compound. This intermediate band slightly overlaps the conduction band and, when a higher accuracy calculation approach like the introduction of a Hubbard‐type empirical correction is used (GGA + U method), it splits leaving a filled narrow band, well isolated inside the band gap. Considering the nanocrystalline form in which these chalcopyrite‐type compounds are used in solar cells, an assessment of the effects of a small crystal size in this system have been carried out with a slab model. In this calculation a decreased bandgap width is observed, which can be as a result of surface termination effects. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of oil extract of garlic (Allium sativum Linn.) on intestinal transference of calcium and its possible correlation with preservation of skeletal health in an ovariectomized rat model of osteoporosis
Authors: Mukherjee Maitrayee , Das Asankur Sekhar , Das Dolan , Mukherjee Sandip , Mitra Smita , Mitra Chandan 
Published: April 2006

AbstractThe present study was undertaken to examine the effects of an oil extract of garlic on the in vivo intestinal transference of calcium, and also to verify its role in maintaining the bone mineral content and bone tensile strength in an ovariectomized rat model of osteoporosis. The results suggest that, in this experimental model, oil extract of garlic promotes intestinal transference of calcium by modulating the activities of both intestinal alkaline phosphatase and Ca2+ activated ATPase. Also the observed low bone mineral content and low bone tensile strength in these rats were significantly restored by garlic oil supplementation. Further, garlic oil supplementation was able to revive partially the bilateral ovariectomy‐induced decrease in the serum estrogen titer. The serum parathyroid hormone level, however, was found unaltered in these rats. The garlic oil supplemented partial recovery in serum estrogen titer in bilaterally ovariectomized rat was found to be persistently associated with enhanced calcium transference and better preservation of bone mineral content. The results of this study propose that the phytoestrogenic efficacy of an oil extract of garlic prevents ovarian hormone deficiency induced bone mineral loss possibly by promoting intestinal transference of calcium through the partial revival of the serum estrogen titer. Copyright © 2006 John Wiley & Sons, Ltd.
Effect on capillary permeability in rabbits of iridoids from Buddleia scordioides
Authors: Gutierrez Rosa Martha Perez , Solis Rosario Vargas , Baez Efren Garcia , Martinez Francisco Martinez 
Published: April 2006

AbstractThe methanol soluble fraction of the leaves of Buddleia scordioides after column chromatography resulted in the isolation of two known iridoid glucosides, catalpol and methylcatalpol. The structures were elucidated by extensive 1D‐2D‐NMR spectroscopy. The structure of methylcatalpol was confirmed by single‐crystal x‐ray diffraction. These compounds showed protective activity against increased (both chloroform and histamine) skin vascular permeability in rabbits. The protective effect was measured as the reduction in leakage of Evans blue. The results showed that the iridoids produced a significant inhibition of microvascular permeability. A comparison was made between the action of the iridoids and a known inhibitor of vascular permeability, troxerutin (50 mg/kg). Methylcatalpol and catalpol were found to be less effective than troxerutin. Copyright © 2006 John Wiley & Sons, Ltd.
The pharmacological effects of Salvia species on the central nervous system
Authors: Imanshahidi Mohsen , Hosseinzadeh Hossein 
Published: April 2006

AbstractSalvia is an important genus consisting of about 900 species in the family Lamiaceae. Some species of Salvia have been cultivated world wide for use in folk medicine and for culinary purposes. The dried root of Salvia miltiorrhiza, for example, has been used extensively for the treatment of coronary and cerebrovascular disease, sleep disorders, hepatitis, hepatocirrhosis, chronic renal failure, dysmenorrhea, amenorrhea, carbuncles and ulcers. S. officinalis, S. leriifolia, S. haematodes, S. triloba and S. divinorum are other species with important pharmacological effects. In this review, the pharmacological effects of Salvia species on the central nervous system will be reviewed. These include sedative and hypnotic, hallucinogenic, skeletal muscle relaxant, analgesic, memory enhancing, anticonvulsant, neuroprotective and antiparkinsonian activity, as well as the inhibition of ethanol and morphine withdrawal syndrome. Copyright © 2006 John Wiley & Sons, Ltd.
A New Highly Convergent Entry to Densely Functionalized Aziridines Based on the Ugi Reaction
Authors: Banfi Luca , Basso Andrea , Guanti Giuseppe , Paravidino Monica , Riva Renata 
Published: April 2006

AbstractThe products of an Ugi‐4CR employing lactate‐derived O‐protected α‐hydroxycarbonyl derivatives underwent, during the subsequent O‐deprotection reaction, an unexpected acyl migration from nitrogen to oxygen. After ester saponification, treatment of the resulting α‐aminoalcohol with mesyl chloride gave rise to a regioselective and stereospecific cyclization to give a series of highly functionalized aziridines in good overall yield.
Production of Small Libraries Optimising and Examining the Scope of Aqueous Acceleration of the Passerini Reaction
Authors: Extance Andrew R. , Benzies David W. M. , Morrish James J. 
Published: April 2006

AbstractIt has been reported that the rate of the Passerini reaction is accelerated in water or in a mixture of water and an organic solvent. Here, the synthesis of small libraries using the Passerini reaction in a biphasic system is described. Examination of the effects of stoichiometry and different reagents demonstrated the ability to produce material of high purity without chromatography, within a specified structural scope.
IMPROVING TAX ADMINISTRATION: A CASE STUDY OF THE UGANDA REVENUE AUTHORITY
Authors: Kangave Jalia 
Published: April 2006

KANGAVE, JALIA, Improving tax administration: a case study of the Uganda Revenue authority, Journal of African Law, 49, 2 (2005): 145–176The prevalence of poverty in developing countries demands that these countries should improvise internal revenue generating projects to supplement, or better still, ultimately significantly reduce dependence on foreign funding. This way self-sustaining economies will be built. One such internal revenue-generating mechanism, and perhaps the most commonly used, is taxation. This paper makes a case for tax administration as a tool of increasing the contribution of tax revenue to Gross Domestic Product, and consequently, a means of reducing the gap between the rich and the poor. The goal of this paper is to propose ways in which the Uganda Revenue Authority (the URA) can improve its tax administration. To achieve this objective, the paper begins with a detailed discussion of the URA's structure and the procedures it follows in collecting taxes. It then highlights the problems that may arise from such structure and procedures, before making proposals on how the URA can reform its organizational structure and processes to maximize its potential in revenue collection capabilities.
A FULL LOAF IS BETTER THAN HALF: THE CONSTITUTIONAL PROTECTION OF ECONOMIC, SOCIAL AND CULTURAL RIGHTS IN MALAWI
Authors: Chirwa Danwood Mzikenge 
Published: April 2006

CHIRWA, DANWOOD MZIKENGE, A full loaf is better than half: the constitutional protection of economic, social and cultural rights in Malawi, Journal of African Law, 49, 2 (2005): 207–241The last two decades have seen a new wave of constitution-making in Africa as many countries changed from autocracy to democracy. Malawi followed the trend by adopting a new Constitution in 1994 to mark the end of a 30-year, dictatorial one-party regime. This Constitution breaks with traditional constitutions by recognizing economic, social and cultural rights. However, few of these rights are entrenched in the Bill of Rights as justiciable rights. The rest are enshrined as unenforceable principles of national policy. These provisions and the jurisprudence they have generated thus far are discussed critically. It is argued that while the Malawian Constitution deserves acclaim for recognizing these rights, the model adopted for protecting them fails to give full effect to the notion of the indivisibility of all rights and is not good enough for a poor country, which is also in transition to democracy. Not only was Malawi's choice of this model not preceded by a careful and reasoned examination of the existing models and the local circumstances, it was also made without wide public consultations. The ways, based on the existing constitutional provisions, in which the protection of these rights can be improved are explored.
Grammatical Deviations in the Spoken and Written Language of Hebrew-Speaking Children With Hearing Impairments
Authors: Tur-Kaspa Hana , Dromi Esther 
Published: April 2006

Purpose:The present study reports a detailed analysis of written and spoken language samples of Hebrew-speaking children aged 11–13 years who are deaf. It focuses on the description of various grammatical deviations in the two modalities.Method:Participants were 13 students with hearing impairments (HI) attending special classrooms integrated into two elementary schools in Tel Aviv, Israel, and 9 students with normal hearing (NH) in regular classes in these same schools. Spoken and written language samples were collected from all participants using the same five preplanned elicitation probes.Results:Students with HI were found to display significantly more grammatical deviations than their NH peers in both their spoken and written language samples. Most importantly, between-modality differences were noted. The participants with HI exhibited significantly more grammatical deviations in their written language samples than in their spoken samples. However, the distribution of grammatical deviations across categories was similar in the two modalities. The most common grammatical deviations in order of their frequency were failure to supply obligatory morphological markers, failure to mark grammatical agreement, and the omission of a major syntactic constituent in a sentence. Word order violations were rarely recorded in the Hebrew samples.Clinical Implications:Performance differences in the two modalities encourage clinicians and teachers to facilitate target linguistic forms in diverse communication contexts. Furthermore, the identification of linguistic targets for intervention must be based on the unique grammatical structure of the target language.
Contextual Variation, Familiarity, Academic Literacy, and Rural Adolescents’ Idiom Knowledge
Authors: Qualls Constance Dean , O’Brien Rose M. , Blood Gordon W. , Hammer Carol Scheffner 
Published: April 2006

Purpose:The paucity of data on idiom development in adolescents, particularly rural adolescents, limits the ability of speech-language pathologists and educators to test and teach idioms appropriately in this population. This study was designed to delineate the interrelationships between context, familiarity, and academic literacy relative to rural adolescents’ idiom knowledge.Method:Ninety-five rural eighth graders (Mage=13.4 years) were quasi-randomly assigned to complete the Idiom Comprehension Test (Qualls & Harris, 1999) in one of three contexts: idioms in a short story (n=25), idioms in isolation (n=32), and idioms in a verification task (n=38). For all conditions, the identical 24 idioms—8 each of high, moderate, and low familiarity (Nippold & Rudzinski, 1993)—were presented. For a subset (N=54) of the students, reading and language arts scores from the California Achievement Tests (5th ed., 1993), a standardized achievement test, were correlated with performance on the idiom test.Results:Performance in the story condition and on high-familiarity idioms showed the greatest accuracy. For the isolation and verification conditions, context interacted with familiarity. Associations existed between idiom performance and reading ability and idiom performance and language literacy, but only for the story and verification conditions. High-proficiency readers showed the greatest idiom accuracy.Clinical Implications:The results support the notion that context facilitates idiom comprehension for rural adolescents, and that idiom testing should consider not only context, but idiom familiarity as well. Thus, local norms should be established. Findings also confirm that good readers are better at comprehending idioms, likely resulting from enriched vocabulary obtained through reading. These normative data indicate what might be expected when testing idiom knowledge in adolescents with language impairments.