bluuebunny/crossref_metadata_2025_split huggingface dataset:
5‐Methoxyfuroxano[3,4‐d]pyrimidine: a highly reactive neutral electrophile
Authors: Remennikov Grigoriy Ya. , Kempf Bernhard , Ofial Armin R. , Polborn Kurt , Mayr Herbert 
Published: August 2003

Abstract5‐Methoxyfuroxano[3,4‐d]pyrimidine (3) reacts with electron‐rich arenes and ethylene derivatives 4 at C‐7 to yield 7‐substituted 6,7‐dihydro‐5‐methoxyfuroxano[3,4‐d]pyrimidines (5). Kinetic investigations of these reactions showed that the rate constants can be described by the correlation equation log k(20 °C) = s(N + E). The electrophilicity parameter E(3) = −8.37 derived from the second‐order rate constants indicates that 3 reacts with nucleophiles of N ≥ 3. Copyright © 2003 John Wiley & Sons, Ltd.
Ab initio molecular dynamics studies on substitution vs electron transfer reactions of substituted ketyl radical anions with chloroalkanes: how do the two products form in a borderline mechanism?
Authors: Yamataka Hiroshi , Aida Misako , Dupuis Michel 
Published: August 2003

AbstractWe present a qualitative analysis, based on ab initio molecular dynamics (MD) calculations, of the SN2/ET mechanistic spectrum for three reactions: (1) HC(CN)O·− + CH3Cl, (2) HC(CN)O·− + (CH3)2CHCl and (3) H2CO·− + CH3Cl, passing through their SN2‐like transition states. Finite temperature (298 K) direct MD simulations indicate that the trajectories for reaction (1) appear to have a propensity towards SN2 products, the propensity for trajectories for reaction (2) seems to be towards ET products, whereas trajectories for reaction (3) appear to show no particular propensity towards either ET or SN2 products. The mechanistic diversity is consistent with the electron‐donating ability of the ketyl species and steric bulkiness of chloroalkanes. We find that the trajectories have characteristics that reflect strongly the types of process [SN2 trajectories in reactions (1) and (3) vs ET trajectories in reactions (2) and (3)]. Trajectories that lead to SN2 products are simple with C—C bond formation and C—Cl bond breaking essentially completed within 50 fs. By contrast, trajectories leading to ET products are more complex with a sudden electron reorganization taking place within 15–30 fs and the major bonding changes and electron and spin reorganizations completed after 250 fs. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamics of reaction of ion pairs in aqueous solution: racemization of the chiral ion pair intermediate of solvolysis of (S)‐1‐(4‐methylphenyl)ethylpentafluorobenzoate
Authors: Tsuji Yutaka , Mori Tetsuo , Toteva Maria M. , Richard John P. 
Published: August 2003

AbstractThe chiral ester
(S)‐1‐(4‐methylphenyl)ethyl pentafluorobenzoate, (S)‐1‐OC(O)C6F5, was prepared and a value of krac = 8.5 × 10−7 s−1 was determined for the rate constant for its racemization to
(R)‐1‐OC(O)C6F5 in 50:50 (v/v) trifluoroethanol–water (I = 0.50, NaClO4). This rate constant is 12 times smaller than ksolv = 1.06 × 10−5 s−1 for the stepwise solvolysis of 1‐OC(O)C6F5, which shows that inversion of the ion‐pair intermediate is a relatively rare event during solvolysis in a largely aqueous solvent, and two times smaller than kiso = 1.6 × 10−6 s−1 for degenerate isomerization which exchanges the position of the ester bridging and non‐bridging oxygens of 1‐OC(O)C6F5. A simple relationship is derived between the empirical rate constant ratio krac/kiso and the microscopic rate constants for reaction of the ion‐pair intermediate within its solvation shell. Substitution of estimated rate constants for reactions of the 1‐(4‐methylphenyl)ethyl carbocation–pentafluorobenzoate anion pair into this equation gives ki = 1.5 × 1010 s−1 for inversion of the chiral ion pair, which is similar to k−d = 1.6 × 1010 s−1 for its separation to free ions. Copyright © 2003 John Wiley & Sons, Ltd.
Kinetic and mechanistic aspects of the direct photodegradation of atrazine, atraton, ametryn and 2‐hydroxyatrazine by 254 nm light in aqueous solution
Authors: Azenha M. E. D. G. , Burrows H. D. , Canle L. M. , Coimbra R. , Fernández M. I. , García M. V. , Peiteado M. A. , Santaballa J. A. 
Published: August 2003

AbstractAtrazine (1), Atraton (2) and Ametryn (3) are photodegraded upon 254 nm irradiation, yielding 2‐OH‐atrazine (4) as a photoproduct. Dealkylation products are also generated, and 4‐ethylamino‐6‐isopropylamino‐(1,3,5)‐triazine was also found as a photoproduct of 3. The main photoreaction is proposed to be an addition–elimination, yielding 4, which subsequently photodegrades. The ease of photodegradation depends on the electron availability at position C‐2, the observed order of photoreactivity being 1 > 3 > 4 > 2. Copyright © 2003 John Wiley & Sons, Ltd.
Supramolecular catalysis induced by polysaccharides. Homogeneous hydrolysis of p‐nitrobenzyl amylose xanthate
Authors: Humeres Eduardo , Gerônimo Vanilde F. , Zwirtes Inês R. , Mazera Edio , Aliev Abil E. 
Published: August 2003

Abstractp‐Nitrobenzyl amylose xanthate (AmXNB) was synthesized and characterized by 13C NMR spectroscopy in solution and the solid state. The degree of substitution (DS), calculated from the sulfur content, was 7.0, and this value was similar to that obtained from solid‐state 13C NMR using the signal of C‐1 as internal standard. The hydrolysis of AmXNB was studied in 10% (v/v) DMSO with µ = 0.5 (KCl) at 25 °C. The basic hydrolysis was pseudo‐first order, but the water‐catalyzed hydrolysis in the pH range 7–9 showed a biphasic plot of ln (ΔAbsorbance) vs time, as has been observed for cellulose xanthate esters, occurring through two parallel reactions with rate constants k′H2O (fast) = 5.3 × 10−5 s−1 and k″H2O (slow) = 3.3 × 10−6 s−1. The fast hydrolysis was more than three orders of magnitude faster than that of the O‐ethyl analog. The activation parameters were ΔH≠ = 20.5 kcal mol−1 and ΔS≠ = +10 cal K−1 mol−1. They showed that the acceleration of the fast hydrolysis of AmXNB and cellulose analogs is due to an entropy of activation effect. There is a linear increase of logk′H2O (fast) with increase in the concentration of the small Li+ ion that produces an increase of the 3‐D hydrogen‐bond network of water while the large singly charged iodide ion has a considerable inverse effect. These results are strongly consistent with the theory that the supramolecular catalysis induced by modified polysaccharide esters is due to the 3‐D hydrogen‐bond network of the water in the solvation shell. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of anti‐inﬂammatory potential of Pavetta indica Linn. leaf extract (family: Rubiaceae) in rats
Authors: Mandal Subhash C. , Mohana Lakshmi S. , Ashok Kumar C. K. , Sur Tapas K. , Boominathan R. 
Published: August 2003

AbstractThe anti‐inﬂammatory potential of methanol extract of Pavetta indica Linn. leaves (Family: Rubiaceae) was evaluated against several models of inﬂammation such as carragenin, histamine and dextran induced pedal inﬂammation in rats. The extract showed 48.41%, 41.10% and 24.22% inhibition respectively; when compared to that of control animals. The effect was comparable with that of the standard drug indomethacin, a standard non‐steroidal anti‐inﬂammatory drug. Simultaneous subplantar administration of the extract and carrageenin in a mixture helps in differentiating true anti‐inﬂammatory action from an apparent anti‐inﬂammatory effect due to counter‐irritant activity. The methanol extract also effectively and signiﬁcantly reduced cotton pellet induced granuloma. The percentage of inhibition was 62.78 at the dose 500 mg/kg, thereby suggesting its activity in the proliferative phase of the inﬂammatory process. Copyright © 2003 John Wiley & Sons, Ltd.
Antioxidant properties of scopoletin isolated from Sinomonium acutum
Authors: Shaw Chin‐Ying , Chen Chen‐Hui , Hsu Chih‐Chieh , Chen Chien‐Chih , Tsai Ying‐Chieh 
Published: August 2003

AbstractScopoletin was isolated from Sinomonium acutum and studied using four experimental models designed to assess antioxidant properties. The results indicated that scopoletin scavenged superoxide anion in the xanthine/xanthine oxidase reaction system in a concentration‐dependent manner, but did not inhibit xanthine oxidase. Scopoletin may therefore be responsible for the superoxide anion scavenging activity seen in Sinomonium acutum extracts and may be of use in preventing superoxide anion‐induced damage in vivo. Copyright © 2003 John Wiley & Sons, Ltd.
Analgesic and anti‐inﬂammatory activity of the leaf essential oil of Laurus nobilis Linn.
Authors: Sayyah M. , Saroukhani G. , Peirovi A. , Kamalinejad M. 
Published: August 2003

AbstractThe leaf essential oil of Laurus nobilis Linn. (Lauraceae) has been evaluated for antinociceptive and anti‐inﬂammatory activities in mice and rats. The essential oil exhibited: (1) a signiﬁcant analgesic effect in tail‐ﬂick and formalin tests; (2) a dose‐dependent anti‐inﬂammatory effect in the formalin‐induced edema and (3) a moderate sedative effect at the anti‐inﬂammatory doses. The analgesic and anti‐inﬂammatory effect of the essential oil was comparable to reference analgesics and non‐steroid anti‐inﬂammatory drugs: morphine and piroxicam. Present results make the essential oil worthy of further investigations. Copyright © 2003 John Wiley & Sons, Ltd.
Podophyllum hexandrum prevents radiation‐induced neuronal damage in postnatal rats exposed in utero
Authors: Sajikumar S. , Goel H. C. 
Published: August 2003

AbstractPodophyllum hexandrum has been shown to mitigate radiation injuries and especially the haemopoietic syndrome in adult mice. To monitor the radiation‐induced changes in the nervous system, the neurons of postnatal young mice and their modiﬁcation by P. hexandrum, were studied histologically for differences in the apical and basal dendritic branching and intersections in the CA1 neurons of the hippocampal region of rats which were delivered a 2 Gy gamma dose while in utero (day 17 of gestation). Irradiation signiﬁcantly reduced the dendritic branching and intersections but pre‐irradiation administration of the extract of P. hexandrum (i.p. 200 mg/kg/b.w., 2 h) reduced the damage in postnatal young mice. These studies indicate that P. hexandrum provides protection to neurons against radiation‐induced damage and the mechanism of neuronal damage and its repair need to be investigated further. Copyright © 2003 John Wiley & Sons, Ltd.
Alkaloids from Brugmansia arborea (L.) Lagerhein reduce morphine withdrawal in vitro
Authors: Capasso Anna , de Feo Vincenzo 
Published: August 2003

AbstractTraditional medicine is a primary source for the study of medicinal plants. In some countries, knowledge about the therapeutic use of medicinal plants is very deep and very often ‘magical’ plants also are used to diagnose and treat illnesses. The study of these plants can help in the research of metabolites active on the central and peripheral nervous system.Brugmansia arborea (L.) Lagerheim (Solanaceae) is used in the northern Peruvian Andes for magic–therapeutic purposes and the present study examined the effect of three pure tropane alkaloids from Brugmansia arborea (L.) Lagerhein (Solanaceae) on morphine withdrawal in vitro. All the tropane alkaloids isolated from Brugmansia arborea (L.) (10−7, 5 × 10−7, 10−6 m) signiﬁcantly and in a concentration dependent manner reduced morphine withdrawal.The results of the present study suggest that these alkaloids may be a potential anti‐additive agent. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of the antimalarial properties and standardization of tablets of Azadirachta indica (Meliaceae) in mice
Authors: Isah A. B. , Ibrahim Y. K. E. , Iwalewa E. O. 
Published: August 2003

AbstractThe antimalarial activities of the tablet suspension of the bark and leaf of Azadirachta indica were evaluated on Plasmodium yoelli nigeriensis infected mice. The tablet suspensions exhibited high prophylactic, mode‐rate suppressive and a very minimal curative schizonticidal effect. No animal was cured of the infection in the curative test and there was not much increase in the survival time of the animals compared with the control. The tablet suspensions from the leaf and bark at a concentration of 800 mg/kg and chloroquine at a concentration of 62.5 mg/kg body weight produced average percentage (%) parasitaemia of 79.6%, 68.2% and 99.5% for leaf, bark and chloroquine, respectively, in chemosuppression. Also in the prophylactic treatment, the tablet suspensions at 800 mg/kg and pyrimethamine at a concentration of 0.35 mg/kg gave an average parasitaemia reduction of 75.3%, 65.6% and 98.3% for the leaf, bark and pyrimethamine, respectively.There was a clear indication that both tablet suspensions from the leaf and bark possess antimalarial activity and a suspension from the former is relatively more effective than the bark. Extrapolation of the results from the antimalarial activity of the tablet suspension of the crude plant parts showed that an adult human would need to ingest a minimum of 48 g of the powdered plant material per day, an amount that is impracticable.A survival index value of 0.33 was obtained with the 800 mg/kg dose level, indicating that the tablet suspension has some moderate beneﬁcial effect. Copyright © 2003 John Wiley & Sons, Ltd.
Anti‐tumour and immuno‐stimulating activities of the fruiting bodies of Paecilomyces japonica, a new type of Cordyceps spp.
Authors: Shin Kuk Hyun , Lim Soon Sung , Lee Sanghyun , Lee Yeon Sil , Jung Sang Hoon , Cho Sae Yun 
Published: August 2003

AbstractThe anti‐tumor and immuno‐stimulating activities of the fruiting bodies of Paecilomyces japonica (PJ), grown on silk‐worm larvae and of Cordyceps sinensis (CS), a wild form of Cordyceps Fungi, were investigated. Ethanol extracts of both fungi, when administered for 9 consecutive days, at 50 and 100 mg/kg i.p., caused a signiﬁcant increase in life span and a signiﬁcant decrease in tumor weights and volumes, in mice inoculated with Sarcoma‐180 tumor cells. Both fungal extracts were demonstrated to exhibit phagocytosis enhancing activity as measured by carbon clearance in mice. PJ extracts, when administered i.p. at 50 mg/kg/day for 3 consecutive days, exhibited a signiﬁcant enhancement of phagocytosis, its potency as expressed by the regression coefﬁcient ratio, RCtr/RCc, being 1.64 (the phagocytosis index = 2). This was approximately the same for that of zymosan (RCtr/RCc = 1.55, PI = 2), a typical phagocytosis enhancer, whereas CS extracts exhibited a moderate phagocytosis enhancing activity at the same dose level (RCtr/RCc = 1.30, PI = 1). Both fungal extracts caused a signiﬁcant increase in an acid phosphatase activity, representing lysosomal enzymes, in macrophages at 20 and 100 µg/ml in vitro, in compliance with in vivo results. These results suggest that the anti‐tumor activity of both fungi might be related to an immuno‐stimulating function. Copyright © 2003 John Wiley & Sons, Ltd.
Ephedra in perspective – a current review
Authors: Abourashed Ehab A. , El‐Alfy Abir T. , Khan Ikhlas A. , Walker Larry 
Published: August 2003

AbstractAlthough the traditional use of Ephedra ‘ma huang’ has been established for thousands of years, its resurgencein the US as a herbal dietary supplement is currently a matter of national controversy. At the heart of the debate are three important questions: (1) the identity and composition of Ephedra products with regard to ephedrine and related alkaloids; (2) the potential therapeutic utility of Ephedra supplements for weight loss or performance enhancement; and (3) potential health risks associated with such uses of Ephedra, particularly in sensitive individuals or in cases of intentional abuse for its stimulant properties. This review surveys the literature on Ephedra with regard to traditional uses, botany, chemistry, analytics, pharmacological effects and health risks. A brief discussion of the central issues in the current debate on the regulation of Ephedra in the United States is included as this is where most of the problems have occurred to date. Copyright © 2003 John Wiley & Sons, Ltd.
Prediction of the Vapor Pressure Boiling Point, Heat of Vaporization and Diffusion Coefficient of Organic Compounds
Authors: Hilal S. H. , Karickhoff S. W. , Carreira L. A. 
Published: August 2003

AbstractThe prototype computer program SPARC has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC solute‐solute physical process models have been developed and tested for vapor pressure (at any temperature), heat of vaporization (at 25C and the boiling point), diffusion coefficient (at 25C) and boiling point (at any pressure) for a relatively large number of organic molecules. The RMS deviation error of the predicted the vapor pressures, heats of vaporization (at any temperature) and boiling points (at any pressure) were close to the intralaboratory experimental errors.
A Combinatorial Approach to the Variable Selection in Multiple Linear Regression: Analysis of Selwood et al. Data Set – A Case Study
Authors: Prabhakar Yenamandra S. 
Published: August 2003

AbstractA combinatorial protocol (CP) is introduced here to interface it with the multiple linear regression (MLR) for variable selection. The efficiency of CP‐MLR is primarily based on the restriction of entry of correlated variables to the model development stage. It has been used for the analysis of Selwood et al data set [16], and the obtained models are compared with those reported from GFA [8] and MUSEUM [9] approaches. For this data set CP‐MLR could identify three highly independent models (27, 28 and 31) with Q2 value in the range of 0.632–0.518. Also, these models are divergent and unique. Even though, the present study does not share any models with GFA [8], and MUSEUM [9] results, there are several descriptors common to all these studies, including the present one. Also a simulation is carried out on the same data set to explain the model formation in CP‐MLR. The results demonstrate that the proposed method should be able to offer solutions to data sets with 50 to 60 descriptors in reasonable time frame. By carefully selecting the inter‐parameter correlation cutoff values in CP‐MLR one can identify divergent models and handle data sets larger than the present one without involving excessive computer time.
NF‐kB signaling blockade abolishes implant particle‐induced osteoclastogenesis
Authors: Clohisy John C. , Hirayama Teruhisa , Frazier Elfaridah , Han Suk‐Ku , Abu‐Amer Yousef 
Published: August 2003

AbstractIn this study we investigated the effect of NF‐kB signaling blockade on polymethylmethacrylate (PMMA) particle‐induced osteoclastogenesis in vitro. We first established effective blockade of NF‐kB activity as tested by electrophoretic mobility shift assays (EMSA). Particle‐induced NF‐kB activation in murine osteoclast precursor cells (CSF‐1‐dependent bone marrow macrophages) was markedly reduced by co‐treatment of the cells with the NF‐kB inhibitors N‐tosyl‐L‐phenylalanine chloromethyl ketone (TPCK) and Calpain Inhibitor I (CPI). This inhibition of NF‐kB activity was associated with blockade of p50 NF‐kB subunit nuclear trans‐location. We then established a direct NF‐kB inhibition approach by utilizing a TAT‐bound, mutant IkB (TAT:IkB46‐317), and demonstrated an inhibitory effect evidenced by decreased NF‐kB DNA binding activity. Having established that these strategies (TPCK, CPI, TAT: IkB46‐317) effectively block NF‐kB activation, we next investigated the effect of these agents on particle‐stimulated osteoclast formation. PMMA particle stimulation of mature osteoclast formation from RANKL‐primed osteoclast precursor cells was blocked by all three inhibitors. To further test the efficacy of NF‐kB blockade, experiments were performed with the TAT:IkB46‐317 mutant peptide in whole bone marrow cultures that contain supporting stromal cells. Again, this inhibitor efficiently blocked particle‐induced osteoclastogenesis. Thus, we have shown that pharmaceutical and molecular blockade of NF‐kB activation inhibits PMMA particle‐directed osteoclastogenesis in vitro. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The absorption of sound in seawater in relation to the estimation of deep-water fish biomass
Authors: Doonan Ian J , Coombs Roger F , McClatchie Sam 
Published: August 2003

Abstract
It is well known that the acoustic estimation of fish abundance requires an estimate of the absorption of sound in seawater. Any errors in this factor will lead to errors in abundance estimates that increase with range. Concerns over the accuracy of the widely used relationship of Francois and Garrison (Journal of the Acoustical Society of America, 72: 896–907; Journal of the Acoustical Society of America, 72: 1879–1890) led to a new analysis of the data they used and a reconsideration of the relationship as a whole.
A major component of sound absorption by seawater is the relaxation frequency of MgSO4, for which there are at least five equations in the literature. We review these and our analysis uses the relaxation equation that best fits the sound-absorption data using modern regression methods. We propose a new equation for the range of frequencies used in fish abundance (10–120 kHz) based on this analysis. For a typical New Zealand deep-water fishery carried out at 38 kHz the new equation gives a biomass 17% lower than that yielded by Francois and Garrison. Whilst we believe that the new equation gives more accurate results for the range of frequencies used in fish abundance, there remains much uncertainty which will only be resolved by the collection of new in situ sound-absorption data in this frequency range.
Inversion of helicopter electromagnetic data to a magnetic conductive layered earth
Authors: Huang Haoping , Fraser Douglas C. 
Published: August 2003

Inversion of airborne electromagnetic (EM) data for a layered earth has been commonly performed under the assumption that the magnetic permeability of the layers is the same as that of free space. The resistivity inverted from helicopter EM data in this way is not reliable in highly magnetic areas because magnetic polarization currents occur in addition to conduction currents, causing the inverted resistivity to be erroneously high.A new algorithm for inverting for the resistivity, magnetic permeability, and thickness of a layered model has been developed for a magnetic conductive layered earth. It is based on traditional inversion methodologies for solving nonlinear inverse problems and minimizes an objective function subject to fitting the data in a least‐squares sense. Studies using synthetic helicopter EM data indicate that the inversion technique is reasonably dependable and provides fast convergence. When six synthetic in‐phase and quadrature data from three frequencies are used, the model parameters for two‐ and three‐layer models are estimated to within a few percent of their true values after several iterations. The analysis of partial derivatives with respect to the model parameters contributes to a better understanding of the relative importance of the model parameters and the reliability of their determination.The inversion algorithm is tested on field data obtained with a Dighem helicopter EM system at Mt. Milligan, British Columbia, Canada. The output magnetic susceptibility‐depth section compares favorably with that of Zhang and Oldenburg who inverted for the susceptibility on the assumption that the resistivity distribution was known.