bluuebunny/crossref_metadata_2025_split huggingface dataset:
New α‐Glucosidase Inhibitors and Antibacterial Compounds fromMyrtus communis L.
Authors: Shaheen Farzana , Ahmad Manzoor , Nahar Khan Shamsun , Samreen Hussain Syeda , Anjum Shazia , Tashkhodjaev Bahodir , Turgunov Kambarali , Sultankhodzhaev Mukhlis N. , Choudhary Muhammad Iqbal , Atta‐ur‐Rahman  
Published: March 2006

AbstractThree new acylphloroglucinols – myrtucommulone D (1), myrtucommulone E (2), and myrtucommulone C (3) – and a new usnic acid derivative usnone A (4) have been isolated from Myrtus communis L., along with the known acylphloroglucinol myrtucommulone B (5), one sterol 8 and six triterpenes 10–15, two flavonoids 6 and 9, and 2,5‐dihydroxy‐4‐methoxybenzophenone (cearoin; 7). The structures of compounds 1, 2, 4, and 5 were also unambiguously determined by single‐crystal X‐ray diffraction analysis. The compounds 1–3 and 5 were found to be more potent α‐glucosidase inhibitors than the clinically used standard acarbose. Compound 3 exhibited the highest activity among all the acylphloroglucinols, with an IC50 (inhibition concentration) = 35.4 ± 1.15 μM. Compounds 1, 2, 4, 7, and 11–15 also exhibited antibacterial activities.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Asymmetric Dihydroxylation of β,γ‐Unsaturated Carboxylic Esterswith Trisubstituted C=C Bonds – Enantioselective Syntheses of Trisubstituted γ‐Butyrolactones
Authors: Kapferer Tobias , Brückner Reinhard 
Published: March 2006

Abstractβ,γ‐Unsaturated esters with stereodefined trisubstitued C=C double bonds were prepared by the Arndt–Eistert homologation of α,β‐unsaturated carboxyl halides, by two‐step methoxycarbonylation of allylbarium reagents, by deconjugation of α,β‐unsaturated esters, and by Horner–Wadsworth–Emmons variants of the Stobbe condensation. Sharpless asymmetric dihydroxylation of the β,γ‐unsaturated esters, followed by spontaneous cyclization, afforded β‐hydroxy‐γ‐lactones in moderate to good yields and with enantiomeric excesses of up to 97 %. Similarly, tetrahydroxy‐γ‐lactones were obtained from diunsaturated esters; these lactones were converted into a bislactone and an unsaturated β‐hydroxy γ‐lactone. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Two‐Step Chemoenzymatic Synthesis of the Natural Pheromone (+)‐Sitophilure Utilizing Isolated, NADPH‐Dependent Ketoreductases
Authors: Kalaitzakis Dimitris , Rozzell J. David , Kambourakis Spiros , Smonou Ioulia 
Published: March 2006

AbstractIsolated, NADPH‐dependent ketoreductases were used for the synthesis of the aggregation pheromone of the pests rice weevil (Sitophilus oryzae L.) and maize weevil (Sitophilus zeamais M.). This is the easiest and most straight forward synthesis of pheromone (+)‐Sitophilure in two steps and an overall yield of 81 %, starting from commercially available 3,5‐heptanedione. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Pd/C: An Old Catalyst for New Applications – Its Use for the Suzuki–Miyaura Reaction
Authors: Felpin François‐Xavier , Ayad Tahar , Mitra Soumya 
Published: March 2006

AbstractIn this review we focus on the widely used Suzuki–Miyaura reaction and show that Pd/C is an efficient catalyst for carbon–carbon bond formation. The advantages and limitations of Pd/C are presented through selected examples. Mechanistic as well as practical aspects are also discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Statistical characterization of circulation patterns and direction of turbulent flow over a waveform structure
Authors: Mazumder Rahul , Mazumder B. S. 
Published: March 2006

AbstractThe objective of this paper is to analyze statistically the turbulence characteristics of flow over an artificial waveform geometry in an open channel, using velocity data collected by 3‐D acoustic doppler velocimeter (ADV). The joint distribution of velocity fluctuations have been studied and modeled using multivariate normal distribution, and its effectiveness is analyzed in the light of explaining turbulent bursting events, like sweeping and ejection. The relationship between the randomness in the directional variations of the 3‐D velocity fluctuations and the intensity of circulation has been studied. We have exploited this relationship and used it in conjunction with the principles of statistical clustering for splitting the region of flow, into different spatially connected segments based on circulation patterns. Directional data analysis has been adopted to visualize the flow pattern over the entire test section, in particular, the circulation bubbles in the region of separated flow. Copyright © 2006 John Wiley & Sons, Ltd.
Modelling small‐business credit scoring by using logistic regression, neural networks and decision trees
Authors: Bensic Mirta , Sarlija Natasa , Zekic‐Susac Marijana 
Published: March 2006

AbstractPrevious research on credit scoring that used statistical and intelligent methods was mostly focused on commercial and consumer lending. The main purpose of this paper is to extract important features for credit scoring in small‐business lending on a dataset with specific transitional economic conditions using a relatively small dataset. To do this, we compare the accuracy of the best models extracted by different methodologies, such as logistic regression, neural networks (NNs), and CART decision trees. Four different NN algorithms are tested, including backpropagation, radial basis function network, probabilistic and learning vector quantization, by using the forward nonlinear variable selection strategy. Although the test of differences in proportion and McNemar's test do not show a statistically significant difference in the models tested, the probabilistic NN model produces the highest hit rate and the lowest type I error. According to the measures of association, the best NN model also shows the highest degree of association with the data, and it yields the lowest total relative cost of misclassification for all scenarios examined. The best model extracts a set of important features for small‐business credit scoring for the observed sample, emphasizing credit programme characteristics, as well as entrepreneur's personal and business characteristics as the most important ones. Copyright © 2005 John Wiley & Sons, Ltd.
Forecasting annual excess stock returns via an adaptive network‐based fuzzy inference system
Authors: Trinkle Brad S. 
Published: March 2006

AbstractIn this study, an adaptive network‐based fuzzy inference system (ANFIS) and a neural network were tested for the ability of these techniques to forecast the annual excess returns of three large publicly traded companies from a time series of said returns. The predictive ability of these techniques was compared with that of an autoregressive moving average (ARMA) model. The Fair–Shiller test was used in the comparisons in order to obtain results that were not subjective and so that conclusions could be made regarding the information used by the techniques in the generation of their forecasts. Since predictive ability does not translate to profitability, a simple trading strategy was used to determine the ability to generate profits from trading upon the forecasts of the respective techniques.As hypothesized, the ANFIS and neural network techniques are able to generate forecasts with significant predictive ability. However, neither technique dominates the other or the ARMA model. In tests of the ability of the techniques to generate profits from their forecasts, a simple trading strategy was used (trading on the predicted sign of the return). The ANFIS and the neural network generated profits in all of the trading scenarios. However, neither technique dominated the other, nor did they consistently outperform the traditional and naive models (strategies). The mixed results in the predictive ability tests and the profitability tests indicate that the conclusions from the study differ based upon the context in which the forecasts are used. Copyright © 2005 John Wiley & Sons, Ltd.
The effect of household characteristics on living standards in South Africa 1993–1998: a quantile regression analysis with sample attrition
Authors: Maitra Pushkar , Vahid Farshid 
Published: March 2006

AbstractThis paper examines whether the dismantling of apartheid has resulted in an improvement in the standard of living for the vast majority of South Africans. The study is based on a panel data set from the Kwazulu‐Natal province. We use weighted quantile regressions to examine the distribution of standards of living, which corrects for the potential bias arising from non‐random sample attrition. Our results show that there has been a significant increase in the spread of the distribution of household expenditure of the non‐white households residing in Kwazulu‐Natal province. Copyright © 2006 John Wiley & Sons, Ltd.
Empirical evidence of income dynamics across EU regions
Authors: Pittau Maria Grazia , Zelli Roberto 
Published: March 2006

AbstractThis paper analyses the distribution of purchasing power standardized per capita income across EU‐12 regions between 1977 and 1996. Dispersion of incomes between regions is measured taking into account their population sizes. The cross‐sectional distributions are initially described by weighted kernel density estimates, revealing a multimodal structure of the distributions, less evident over the period. This evidence is supported by a bootstrap test. To detect homogeneous groups of regions, the empirical distributions are approximated by a finite mixture of normal densities. The components of the mixture represent clusters of poor/rich regions, while the mixing proportions the allocation over the poor and the rich components. The number of components is assessed by a bootstrap LR test, and the goodness of fit by a kernel density‐based test. Income mobility is modelled by the stochastic kernel, the continuous counterpart of the transition probability matrix. The main implication is a very slow process of catching up of the poorest regions with the richer ones and a process of shifting away of a small group of very rich regions. This evidence is reflected in the shape of the ergodic distribution, which is well fitted by a two‐component mixture model. Copyright © 2006 John Wiley & Sons, Ltd.
Generalized long memory processes, failure of cointegration tests and exchange rate dynamics
Authors: Smallwood Aaron D. , Norrbin Stefan C. 
Published: March 2006

AbstractThis paper presents evidence that the equilibrium relationship in a system of nominal exchange rates is best described as a stationary GARMA process. The implementation of the GARMA methodology helps explain conflicting and puzzling results from the use of linear cointegration and fractional cointegration methods. Furthermore, we use Monte Carlo analysis to document problems with standard cointegration tests when the attraction process is distributed as a long memory GARMA process. Copyright © 2006 John Wiley & Sons, Ltd.
Deriving target selection rules from endogenously selected samples
Authors: Donkers Bas , Paap Richard , Jonker Jedid‐Jah , Franses Philip Hans 
Published: March 2006

AbstractThe selection of the most profitable customers in a customer database for targeted activities is often done based on observed behaviour in the past. Consequently, databases arising from the responses to, for example, direct mailings in the past are not random samples. When not all heterogeneity across customers is observed, target selection will be based on unobserved heterogeneity and hence it is endogenous. We develop a method to adjust the likelihood function of latent class models to correct for this endogenous sampling process. We apply this technique to the selection of mail targets for a Dutch charity. Based on a joint model for the response rate and the amount donated, we create a target selection rule that maximizes expected revenues. Copyright © 2006 John Wiley & Sons, Ltd.
Theoretical study on the [Si, C, N, O] potential energy surface
Authors: Yu Guang‐Tao , Huang Xu‐Ri , Ding Yi‐Hong , Sun Chia‐Chung , Tang Au‐Chin 
Published: March 2006

AbstractThe structures, energetics, spectroscopies, and stabilities of the doublet [Si, C, N, O] radical are explored at the density functional theory and ab initio levels. Sixteen isomers are located, connected by 29 interconversion transition states. At the CCSD(T)/6‐311+G(2df)//QCISD/6‐311G(d)+ZPVE level, the lowest lying isomer is a linear SiNCO 1 (0.0 kcal/mol) mainly featuring a cumulene | · Si = N = C = O. The second and third low‐lying isomers are bent OSiCN 2 (8.8) and bent OSiNC 3 (11.1), respectively. All the three low‐lying isomers 1, 2, 3, and another high‐lying species 5 (75.4) with a linear SiCNO structure are shown to have considerable kinetic stability and may be experimentally observable. The predicted results of isomers 1 and 2 are consistent with the previous mass spectrometry experiments. Moreover, the fourth low‐lying species SiOCN 4 (23.9) with bent structure is expected to be observable in low‐temperature environments. The bonding nature of the five isomers 1, 2, 3, 4, and 5 is analyzed. The calculated results are compared with those of the analogous molecules C2NO and Si2NO. Implications in interstellar space and N,O‐doped SiC vaporization processes are also discussed. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 749–761, 2006
Orbital‐orthogonality constraints and basis‐set optimization
Authors: Penotti Fabio E. 
Published: March 2006

AbstractA new procedure is presented for introducing arbitrary orbital‐orthogonality constraints in the variational optimization of otherwise nonorthogonal multiconfiguration electronic wave functions. It is based on suitable analytical changes to the expressions for the first and second derivatives of the electronic energy with respect to the independent variational parameters, and can be applied in the presence of symmetry constraints. It is tested using a second‐derivative optimization procedure, the Optimized Basis Set—Generalized Multiconfiguration Spin‐Coupled (OBS‐GMCSC) approach, that can treat basis‐function exponential parameters as variational parameters, to be optimized simultaneously with configuration, spin‐coupling, and orbital coefficients. This enables rigorous optimization of basis‐set exponential parameters even for fully orthogonal multiconfiguration wave functions. Test calculations are carried out, with optimized even‐tempered basis sets, on Li2 and on the CH radical. For the latter, special attention is paid to the electronic spin density at the nuclei. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 762–772, 2006
Strike a balance: Optimization of backbone torsion parameters of AMBER polarizable force field for simulations of proteins and peptides
Authors: Wang Zhi‐Xiang , Zhang Wei , Wu Chun , Lei Hongxing , Cieplak Piotr , Duan Yong 
Published: March 2006

AbstractBased on the AMBER polarizable model (ff02), we have reoptimized the parameters related to the main‐chain (Φ, Ψ) torsion angles by fitting to the Boltzmann‐weighted average quantum mechanical (QM) energies of the important regions (i.e., β, PII, αR, and αL regions). Following the naming convention of the AMBER force field series, this release will be called ff02pol.rl The force field has been assessed both by energetic comparison against the QM data and by the replica exchange molecular dynamics simulations of short alanine peptides in water. For Ace‐Ala‐Nme, the simulated populations in the β, PII and αR regions were approximately 30, 43, and 26%, respectively. For Ace‐(Ala)7‐Nme, the populations in these three regions were approximately 24, 49, and 26%. Both were in qualitative agreement with the NMR and CD experimental conclusions. In comparison with the previous force field, ff02pol.rl demonstrated good balance among these three important regions. The optimized torsion parameters, together with those in ff02, allow us to carry out simulations on proteins and peptides with the consideration of polarization. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 781–790, 2006
Stereospecific assignments of protein NMR resonances based on the tertiary structure and 2D/3D NOE data
Authors: Pristovšek Primož , Franzoni Lorella 
Published: March 2006

AbstractIn many cases of protein structure determination by NMR a high‐quality structure is required. An important contribution to structural precision is stereospecific assignment of magnetically nonequivalent prochiral methylene and methyl groups, eliminating the need for introducing pseudoatoms and pseudoatom corrections in distance restraint lists. Here, we introduce the stereospecific assignment program that uses the resonance assignment, a preliminary 3D structure and 2D and/or 3D nuclear Overhauser effect spectroscopy peak lists for stereospecific assignment. For each prochiral group the algorithm automatically calculates a score for the two different stereospecific assignment possibilities, taking into account the presence and intensity of the nuclear Overhauser effect (NOE) peaks that are expected from the local environment of each prochiral group (i.e., the close neighbors). The performance of the algorithm has been tested and used on NMR data of α‐helical and β‐sheet proteins using homology models and/or X‐ray structures. The program produced no erroneus stereospecific assignments provided the NOEs were carefully picked and the 3D model was sufficiently accurate. The set of NOE distance restraints produced by nmr2st using the results of the SSA module was superior in generating good‐quality ensembles of NMR structures (low deviations from upper limits in conjunction with low root‐mean‐square‐deviation values) in the first round of structure calculations. The program uses a novel approach that employs the entire 3D structure of the protein to obtain stereospecific assignment; it can be used to speed up the NMR structure refinement and to increase the quality of the final NMR ensemble even when no scalar or residual dipolar coupling information is available. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 791–797, 2006
Production of low methoxyl pectin using immobilized pectinmethylesterase silica from acerola (Malpighia glabra L.)
Authors: de Assis Sandra A , Ferreira Bruno S , Fernandes Pedro , Trevisan Henrique C , Cabral Joaquim MS , Oliveira Olga MMF 
Published: March 2006

AbstractThe aim of this work was to develop an efficient reactor for the production of low methoxyl pectin, using pectinmethylesterase (PME, EC 3.1.1.11) from acerola immobilized on silica. The immobilized enzyme was used in up to 50 successive bioconversion runs at 50 °C with an efficiency loss of less than 20%. The fixed‐bed reactor (6.0 × 1.5 cm) was prepared using PME immobilized in glutaraldehyde‐activated silica operated at 50 °C with an optimum flow rate of 10 mL h−1. The bioconversion yield was shown to strongly depend on the nature of the enzymatic preparation. An efficiency of 44% was achieved when concentrated PME was used, compared with only 30% with purified PME, both after an 8‐h run. The process described could provide the basis for the development of a commercial‐scale process. Copyright © 2006 Society of Chemical Industry
Bioprocessing of avian eggshells and eggshell membranes using lactic acid bacteria
Authors: Rubilar Osvaldo E , Healy Michael G , Healy Adrienne 
Published: March 2006

AbstractLactic acid fermentation combined with chemical treatments is a new alternative to chemical extraction of by‐products from organic wastes such as prawn and krill shells. This study investigated the potential of whole eggshells (WES) and eggshell membranes (ESM) fermentation to provide a multi‐product process, thereby eliminating waste and generating revenue. Dry WES and dry ESM were treated separately in a 2‐L reactor using a glucose solution, with and without citric acid solution (CA) and commercial lactic acid bacteria as inoculants, to determine the protein and carbohydrate contents from the final products. Through this process, protein and calcium removal is achieved by enzymatic action on the tissues and by dissolving of calcium by organic acids, respectively. The best fermentation condition was obtained by including CA in the process. Mass balances from the WES and ESM treatments were carried out to identify the phases with major amount of protein, carbohydrate and calcium. In the WES treatments with/without CA, the liquid phase turned out to contain the major amount of protein (85.4 and 73.2%) from the final product. On the other hand, the solid phase turned out to contain mainly ash (80.47 and 80.49%), with high calcium content, from the final product. The high‐solubility dialysed liquid phase (LP1) from the ESM treatment turned out to contain the major amount both of soluble protein (88.3%) and of exopolysaccharides expressed as carbohydrates (4.3%) and the low‐solubility dialysed liquid phase (LP2) turned out to contain the major amount of insoluble protein (60.2%) from the final product. In addition, the first‐precipitation solid phase (SP1) from the ESM treatment turned out to contain the major amount of ash (60.5%) from the final product. The foamy phase and the liquid phase from the WES treatment using CA were analysed by SDS–PAGE, two‐dimensional electrophoresis and electrospray ionisation ion‐trap mass spectrometry. Four proteins related to the hen eggshells were identified from these phases: chicken heat shock protein (Gallus gallus), glucose‐regulated protein precursor, calcyclin and 60s acidic ribosomal protein p2 were identified in the liquid phase and a protein homologous with calmodulin, a ubiquitous intracellular Ca2+ receptor, was identified in the foamy phase. Copyright © 2006 Society of Chemical Industry
Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 2: kinetics
Authors: Pinto Lisete DS , dos Santos Luisa M Freitas , Santos Regina CD , Al‐Duri Bushra 
Published: March 2006

AbstractThe results of a detailed investigation into the kinetics of quinoline oxidation in supercritical water are presented. The novel kinetic data presented were obtained in a continuously operated, plug flow reactor where parameters such as temperature, pressure, residence time and stoichiometric ratio of oxidant to quinoline were investigated and detailed in the companion paper (Pinto LDS, Freitas dos Santos LMF, Al‐Duri B and Santos RCD, Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 1: effect of key operating parameters. J Chem Technol Biotechnol). An induction time was experimentally observed, ranging from 1.5 to 3.5 s, with longer times observed in experiments carried out at lower temperatures. A pseudo‐first‐order rate expression with respect to quinoline concentration (with oxygen excess) was first adopted and the activation energy of 234 kJ mol−1 and a pre‐exponential factor of 2.1 × 1014 s−1 were estimated. Furthermore, an integral power rate model expression was established, attributing a reaction order for quinoline as 1 and for oxygen as 0.36. An activation energy and pre‐exponential factor for this model were determined as 224 kJ mol−1 and 3.68 × 1014 M−0.36 s−1, respectively. A global rate expression was then regressed for the quinoline reaction rate from the complete set of data. The resulting activation energy was 226 ± 19 kJ mol−1 and the pre‐exponential factor was 2.7 × 1013 ± 2 M−0.1 s−1. The reaction orders for quinoline and oxygen were 0.8 ± 0.1 and 0.3 ± 0.1, respectively. It was shown that the least‐squares regression method provided the best‐fit model for experimental results investigated in this study. Copyright © 2006 Society of Chemical Industry