bluuebunny/crossref_metadata_2025 huggingface dataset:
Graft copolymerization of acrylate monomers onto sulfonated jute–cotton blended fabric
Authors: Mondal Md. Ibrahim H. , Farouqui Faisul Islam , Salam M. Abdus
Published: March 2006

Graft copolymerization of acrylate monomers, e.g., methyl methacrylate and ethyl methacrylate, onto bleached sulfonated jute–cotton‐blended fabric was carried out in an aqueous medium, using potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in a nitrogen atmosphere. The parameter variables, e.g., concentrations of monomer, potassium persulfate, ferrous sulfate, reaction time, and reaction temperature, directly influenced the percent graft yield. The percent graft yield increased to a certain value in each variable, and the percent graft yield of methyl methacrylate and ethyl methacrylate was about 15.9 and 17.1%, respectively. Polymer grafting was characterized by thermogravimetric analysis, infrared spectroscopy, and X‐ray diffractometry. Grafting improved the thermal stability, protected from photo‐oxidative degradation, decreased the dyeability, and had positive impact on fastness characteristics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4393–4398, 2006
Formation of inorganic (TaC, TaN) fibers by thermal decomposition of cellulose acetate–tantalum alkoxide precursor gel fibers
Authors: Nakane Koji , Ogata Nobuo , Kurokawa Youichi
Published: March 2006

Precursor gel fiber was formed by extruding cellulose acetate spinning solution into Tantalum (Ta) pentaethoxide acetone solution in a coagulation bath. Gel formation must be due to the coordination of Ta to OH and CO groups on the pyranose ring. The resultant precursor gel fiber was converted into carbide (TaC) or nitride (TaN) fibers by pyrolyzing them in Ar, N2, or NH3 atmospheres. TaC and TaN fibers can be obtained near theoretical temperatures calculated from thermodynamics data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4320–4324, 2006
New method for the synthesis of clay/epoxy nanocomposites
Authors: Wang H. , Hoa S. V. , Wood‐Adams P. M.
Published: March 2006

A new liquid–liquid method for the synthesis of epoxy nanocomposites was developed. This new method improved the dispersion and exfoliation of the organoclay in the polymer matrix, thus improving the end‐use properties. The microstructure and physical properties of the clay/epoxy nanocomposite synthesized by the new method were studied. Rheological tests of the uncured epoxy–organoclay system demonstrated that this method resulted in a great increase in viscosity, much more than the most commonly used direct‐mixing method. The Krieger–Dougherty model successfully described the dispersion of the clay layers in the uncured epoxy. In the 5 wt % organoclay nanocomposite, compressive tests on the cured samples showed that there was a 45% increase in the maximum strength, a 10% increase in the yield strength, and a 26% increase in the modulus over the pure epoxy–amine cured system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4286–4296, 2006
Synthesis, characterization, and kinetic investigation of acrylic monomers derived from acetaminophen and ρ‐cresol as model drug molecules
Authors: Vezvaie Mansoor , Taghizadeh S. Mojtaba , Gholami Mohammed R.
Published: March 2006

In this work, the synthesis, characterization, and kinetic investigation of the free‐radical polymerization of 4‐acetylaminobenzene propenoic ester (ABPE) and 4‐methylbenzene propenoic ester (MBPE) were studied. The kinetic behaviors of ABPE and MBPE in the polymerization initiated by azobisisobutyronitrile in dimethylformamide solutions at temperatures between 50 and 120°C were investigated, and experimental and theoretical conversion–time curves were compared. Both monomers showed a polymerization ceiling temperature (Tc). Tc was calculated with experimental values of kp/k with a constant concentration of 0.7 mol/L for monomers. Tc was about 141 and 131°C for ABPE and MBPE, respectively. In addition, the solvent effect on the polymerization reaction was investigated via the calculation of the solvent chain‐transfer constant (Cs) for the ABPE monomer. Then, Cs was determined from the average degree of polymerization measured with gel permeation chromatography and the calculation of the overall rate of polymerization at 60°C. The results showed that dimethylformamide as a solvent had no effect on the rate of polymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4369–4374, 2006
Dyeing properties of net‐modified cotton fabric with triazine derivative containing the multireactive and multicationic groups
Authors: Xie Kongliang , Sun Yan , Hou Aiqin
Published: March 2006

Cotton fabric was modified with a 1,3,5‐triazine derivative containing the multireactive and multicationic groups, 2,4,6‐tri[(2‐hydroxy‐3‐trimethyl‐ammonium)propyl]‐1,3,5‐triazine chloride (Tri‐HTAC). Compared with unmodified cellulose, the net‐modified cotton cellulose has different dyeing properties. The modified cotton was dyed with reactive dyes without the addition of salt. The color yield was higher than that on unmodified cotton, despite the addition of large amounts of salt in the latter case. After dyeing, compared with unmodified cellulose with reactive dyes, the reflectance spectrums of modified cotton did not change. The modified cotton got better wash fastness than the unmodified cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4388–4392, 2006
Metabolism of PER.C6TM cells cultivated under fed‐batch conditions at low glucose and glutamine levels
Authors: Maranga Luis , Goochee Charles F.
Published: March 2006

This is the first study to examine PER.C6TM cell glucose/energy and glutamine metabolism with fed‐batch cultures at controlled low glutamine, low glucose, and simultaneous low glucose and low glutamine levels. PER.C6TM cell metabolism was investigated in serum‐free suspension bioreactors at two‐liter scale. Control of glucose and/or glutamine concentrations had a significant effect on cellular metabolism leading to an increased efficiency of nutrient utilization, altered byproduct synthesis, while having no effect on cell growth rate. Cultivating cells at a controlled glutamine concentration of 0.25 mM reduced qGln and q by approximately 30%, qAla 85%, and qNEAA 50%. The fed‐batch control of glutamine also reduced the overall accumulation of ammonium ion by approximately 50% by minimizing the spontaneous chemical degradation of glutamine. No major impact upon glucose/energy metabolism was observed. Cultivating cells at a glucose concentration of 0.5 mM reduced qGlc about 50% and eliminated lactate accumulation. Cells exhibited a fully oxidative metabolism with Y of approximately 6 mol/mol. However, despite no increase in qGln, an increased ammonium ion accumulation and Y were also observed. Effective control of lactate and ammonium ion accumulation by PER.C6TM cells was achieved using fed‐batch with simultaneously controlled glucose and glutamine. A fully oxidative glucose metabolism and a complete elimination of lactate production were obtained. The qGln value was again reduced and, despite an increased q compared with batch culture, ammonium ion levels were typically lower than corresponding ones in batch cultures, and the accumulation of non‐essential amino acids (NEAA) was reduced about 50%. In conclusion, this study shows that PER.C6TM cell metabolism can be confined to a state with improved efficiencies of nutrient utilization by cultivating cells in fed‐batch at millimolar controlled levels of glucose and glutamine. In addition, PER.C6TM cells fall into a minority category of mammalian cell lines for which glutamine plays a minor role in energy metabolism. © 2006 Wiley Periodicals, Inc.
Event‐driven time‐optimal control for a class of discontinuous bioreactors
Authors: Moreno Jaime A. , Betancur Manuel J. , Buitrón Germán , Moreno‐Andrade Iván
Published: March 2006

Discontinuous bioreactors may be further optimized for processing inhibitory substrates using a convenient fed‐batch mode. To do so the filling rate must be controlled in such a way as to push the reaction rate to its maximum value, by increasing the substrate concentration just up to the point where inhibition begins. However, an exact optimal controller requires measuring several variables (e.g., substrate concentrations in the feed and in the tank) and also good model knowledge (e.g., yield and kinetic parameters), requirements rarely satisfied in real applications. An environmentally important case, that exemplifies all these handicaps, is toxicant wastewater treatment. There the lack of online practical pollutant sensors may allow unforeseen high shock loads to be fed to the bioreactor, causing biomass inhibition that slows down the treatment process and, in extreme cases, even renders the biological process useless. In this work an event‐driven time‐optimal control (ED‐TOC) is proposed to circumvent these limitations. We show how to detect a “there is inhibition” event by using some computable function of the available measurements. This event drives the ED‐TOC to stop the filling. Later, by detecting the symmetric event, “there is no inhibition,” the ED‐TOC may restart the filling. A fill‐react cycling then maintains the process safely hovering near its maximum reaction rate, allowing a robust and practically time‐optimal operation of the bioreactor. An experimental study case of a wastewater treatment process application is presented. There the dissolved oxygen concentration was used to detect the events needed to drive the controller. © 2006 Wiley Periodicals, Inc.
Cognitive profiles of adult developmental dyslexics: theoretical implications
Authors: Reid Agnieszka A. , Szczerbinski Marcin , Iskierka‐Kasperek Ewa , Hansen Peter
Published: March 2006

The aim of this study was to establish cognitive profiles of dyslexic adults on tests developed within the three main theories of developmental dyslexia: phonological, visual magnocellular and cerebellar and to investigate which theory can account for these profiles. The sample consisted of 15 Polish university students or alumni with a formal diagnosis of dyslexia, without ADHD and 15 controls matched on education, age, gender, IQ and handedness. The results revealed a striking heterogeneity of profiles. Nine dyslexics exhibited only a phonological deficit; one a phonological and a visual magnocellular deficit; a further three a phonological and a cerebellar deficit; two either a cerebellar or a visual magnocellular deficit. None of the three main theories of dyslexia can account for all the cases studied here. It is suggested that the best account of these data is in terms of different sub‐types of dyslexia with different underlying causes, such as phonological, visual magnocellular and cerebellar, or a combination of these. However, an account in terms of Ramus' (Trends, Neurosci. 2004; 27(12):720–726) model, according to which the phonological deficit is a core deficit in dyslexia and other deficits (magnocellular and cerebellar), are just co‐morbid markers without a causal relationship to dyslexics' literacy difficulties, cannot currently be ruled out. Copyright © 2006 John Wiley & Sons, Ltd.
Calculation of the Ligating Strength of N‐Heterocyclic Germylenes – Extending the π‐Acceptor Range
Authors: Kühl Olaf , Lifson Kirstin , Langel Walter
Published: March 2006

The ligand behaviour of N‐heterocyclic germylenes (NHGe) with respect to their σ‐donor ability, π‐acceptor strength and net electron donating ability is determined by calculating their molecular electrostatic potential (MEP). Correlation of the MEP to the Tolman Electronic Parameter (TEP) is achieved using a family of phosphite ligands. The results indicate that the π‐acceptor strength of NHGe reaches significantly beyond that of phosphites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
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

Three 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

β,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

Isolated, 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

In 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

The 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

Previous 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

In 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

This 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

This 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

This 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

The 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

The 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

A 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

Based 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

In 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

The 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

Lactic 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

The 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
Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 1: effect of key operating parameters
Authors: Pinto Lisete DS , dos Santos Luisa M Freitas , Al‐Duri Bushra , Santos Regina CD
Published: March 2006

This work presents the supercritical water oxidation (SCWO) of quinoline, a nitrogen‐containing organic compound found in pharmaceutical wastewaters, to products that are more readily biodegradable. The effects of the operating variables, namely process temperature, stoichiometric ratio of oxidant to organic, residence time and system pressure were studied in order to optimise quinoline removal efficiency and to investigate the fate of carbon and nitrogen after oxidation. Hydrolysis experiments undertaken in the range 480–650 °C showed no significant degradation of quinoline. The present study confirmed that, as an alternative to incineration, the process is fast and effective in treating quinoline in water, converting it into primarily carbon dioxide (CO2), water (H2O) and nitrogen gas (N2) and to a lesser extent ammonium ions (NH4+). Temperature was shown to be the primary variable in the complete destruction of quinoline and TOC reduction, upon operating at around 250 bars. Essentially, complete quinoline removal was observed above 575 °C and complete TOC removal was obtained at 650 °C, where CO2 was the main reaction product. Copyright © 2006 Society of Chemical Industry
From multi‐scale methodology to systems biology: to integrate strain improvement and fermentation optimization
Authors: Zhang Siliang , Ye Bang‐Ce , Chu Ju , Zhuang Yingping , Guo Meijin
Published: March 2006

Strain improvement and fermentation optimization are two fundamental tasks in industrial fermentation. Multi‐scale study on the optimization of industrial fermentation has been proved to be an efficacious method. However, correlations of data used on inter‐scale observation and operation are indirect, empirical and there is still much to be improved. Advances in our understanding of complex biological systems are addressed by comprehensive studies that include high‐throughput measurements of mRNA, proteins, and low molecular weight metabolites over time and varied conditions during fermentation. Systems biology can be used to relate these omics datasets to the microbial genome and culture conditions in a bioreactor, then identify some new targets for metabolic engineering and elucidate the molecular mechanism of environmental effects. This approach provides a potentially powerful tool for integrating strain improvement and process optimization for industrial biotechnology. Copyright © 2006 Society of Chemical Industry
Are ionic liquids kosmotropic or chaotropic? An evaluation of available thermodynamic parameters for quantifying the ion kosmotropicity of ionic liquids
Authors: Zhao Hua
Published: March 2006

Ion hydration is critically important to many biological applications, including protein unfolding. However, the hydration of ionic liquids (a new type of organic salts) is not well understood. One property for characterizing the effect of ion hydration is kosmotropicity. To quantify the ion kosmotropicity, this review evaluated several thermodynamic parameters including B‐coefficients, structural entropies, structural volumes, and ion mobility. The availability and reliability of experimental data and various models for these parameters were examined for ionic liquids. The relationship and comparison of these parameters are also discussed. Smaller pyridinium and imidazolium cations in ionic liquids are more likely to be chaotropes or borderline ions owing to their hydrophobic hydration. The kosmotropicity of anions varies. Copyright © 2006 Society of Chemical Industry
Mn‐peroxidase production by Panus tigrinus CBS 577.79: response surface optimisation and bioreactor comparison
Authors: Quaratino Daniele , Fenice Massimiliano , Federici Federico , D'Annibale Alessandro
Published: March 2006

This study reports the statistical optimisation through response surface methodology of the growth medium for Panus tigrinus manganese‐dependent peroxidase (MnP) production in shaken culture. Three crucial variables, including carbon source, malonic acid and Mn2+, were optimised in a nitrogen‐limited medium. Sucrose was the best carbon source for MnP production. Mn2+ ions and malonic acid significantly stimulated MnP production at an optimal concentration of 53 mg dm−3 and 8.2 mmol dm−3, respectively, resulting in 0.83 U cm−3. Further experiments were performed in lab‐scale stirred tank (STR) and bubble‐column (BCR) reactors using the previously optimised liquid medium. BCR proved to be more adequate than STR in supporting MnP production, leading to 3700 U dm−3 after 144 h with a productivity of 25.7 U dm−3 h−1. On a comparative basis with other production data in lab‐scale reactors, these results appear to be compatible with scale transfer. Copyright © 2006 Society of Chemical Industry
Performance assessment of a UASB–anoxic–oxic system for the treatment of tomato‐processing wastes
Authors: Gohil Alpesh , Nakhla George
Published: March 2006

An upflow anaerobic sludge blanket (UASB)–anoxic–oxic system was used to achieve biochemical oxygen demand, NH4 and total suspended solids (TSS) criteria of 15, 1 and 15 mg dm−3 at 1.17 days of system hydraulic retention time during treatment of tomato‐processing waste. The incorporation of an anoxic tank was found to affect the improvement in sludge‐settling characteristics, as reflected by about 25–33% reduction in the sludge volume index, along with final effluent TSS and soluble biochemical oxygen demand concentrations of 13 and 9 mg dm−3, respectively, which met the discharge criteria. Despite incomplete denitrification, sludge settleability was very good (sludge volume index < 60 cm3 g−1) owing to reduction in volatile suspended solids/TSS ratio from 0.75 to 0.6 as a result of higher alkalinity in the UASB effluent. Also in this study, phosphorus release was observed in the anoxic tank, predominantly due to abundance of acetic acid in the UASB effluent. A phosphate release of 5.4 mg P dm−3 was observed in the anoxic tank with subsequent P uptake in the following aerobic stage. Copyright © 2006 Society of Chemical Industry
Gas hold‐up estimation in bubble columns using passive acoustic waveforms with neural networks
Authors: Al‐Masry Waheed A , Abdennour Adel
Published: March 2006

Passive acoustic waveforms produced experimentally from a bench‐scale two‐phase bubble column were recorded using a miniature hydrophone at three axial positions. The generated acoustic waveforms were processed and trained using artificial intelligence against global gas hold‐up measurements. Two neural network architectures, the radial basis function (RBF) neural network and the recurrent Elman neural network, were employed. Both neural network techniques achieved accurate gas hold‐up estimation, characterised by low mean square errors of 2.70 and 1.68% for the RBF and recurrent Elman networks respectively. The designed and trained neural networks were found to be a powerful tool for learning and replicating complex two‐phase patterns. Passive acoustic waveforms were found to be a useful measuring technique for gas hold‐up estimation in bubble columns under moderate operating conditions. Copyright © 2006 Society of Chemical Industry
Effects of leptin administration on the endocrine pancreas and liver in the lizard Podarcis sicula
Authors: Paolucci Marina , Buono Silvana , Sciarrillo Rosaria , Putti Rosalba
Published: March 2006

In this study, we investigated the presence of leptin receptor in pancreatic islets and the effect of exogenous leptin administration in Podarcis sicula on glucose metabolism. Our data show the presence of leptin receptor immunoreactivity in the endocrine pancreas suggesting that leptin may act at a peripheral level as previously postulated in mammals. The effects of short‐ and long‐term and dose–response treatment with supraphysiological concentrations of leptin on circulating levels of insulin, glucagon and glucose in the blood have been evaluated. Taken together, our results indicate that leptin treatment was followed by an increase in insulin, glucagon and glucose in the blood, depending on the dose of leptin. Moreover, leptin treatment brought about a decrease of glycogen and the appearance of tyrosine‐phosphorylated proteins in the liver. This study shows that in the lizard P. sicula leptin is involved in glucose metabolism. J. Exp. Zool. 305A, 2006. © 2006 Wiley‐Liss, Inc.
Mass spectrometry for the study of protein glycation in disease
Authors: Niwa Toshimitsu
Published: March 2006

The structural elucidation of advanced glycation end‐product (AGE)‐modified proteins and quantitative analysis of free AGEs have been successfully performed, by use of mass spectrometry (MS) in plasma and tissues of patients with AGE‐related diseases, such as diabetes mellitus, uremia, cataract, and liver cirrhosis. Matrix‐assisted laser desorption/ionization (MALDI)‐MS made it possible to directly analyze the AGE‐modified proteins such as albumin and IgG. However, because the direct structural analysis of intact AGE‐modified proteins is often not easy due to the formation of broad and poorly resolved peaks, peptide mapping after enzymatic hydrolysis was introduced into the analysis of AGE‐modified proteins and the site‐specific analysis of defined AGEs by MALDI‐MS. Liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS) has been employed not only for the structural elucidation of enzymatically hydrolyzed AGEs‐modified peptides but also for simultaneous quantification of free AGEs in plasma and tissues of patients. Based on many studies that use MS for the analysis of AGEs, there is no doubt as to the important role of protein‐linked AGEs in several diseases. © 2006 Wiley‐Liss, Inc.
Antitumor action of curcumin in human papillomavirus associated cells involves downregulation of viral oncogenes, prevention of NFkB and AP‐1 translocation, and modulation of apoptosis
Authors: Divya Chandrasekhar S. , Pillai M. Radhakrishna
Published: March 2006

Curcumin (diferuloyl methane), the major yellow pigment from the rhizomes of turmeric (Curcuma longa Linn), has anticancer properties. Infection with high‐risk human papillomaviruses (HPV) leads to development of cervical carcinoma, predominantly through the action of viral oncoproteins E6 and E7.The present study aims at analyzing the antitumor and antiviral properties of curcumin, on HPV associated cervical cancer cells. Our findings indicate curcumin to be cytotoxic to cervical cancer cells in a concentration‐dependent and time‐dependent manner. The cytotoxic activity was selectively more in HPV16 and HPV18 infected cells compared to non‐HPV infected cells. Balance between tumor cell proliferation and spontaneous cell death via apoptosis had an important role in regulation of tumor cell growth. Curcumin‐induced apoptosis in cervical cancer cells. Morphological hallmarks of apoptosis such as nuclear fragmentation and internucleosomal fragmentation of DNA were observed. Curcumin also selectively inhibited expression of viral oncogenes E6 and E7, evident from RT‐PCR and Western blotting data. Electrophoretic mobility shift assay revealed that activation of NFκB‐induced by TNFα is downregulated by curcumin. Curcumin blocked IkBα phosphorylation and degradation, leading to abrogation of NFκB activation. Curcumin also downregulated the expression of COX‐2, a gene regulated by NFκB. Binding of AP‐1, an indispensable component for efficient epithelial tissue‐specific gene expression of HPV was also selectively downregulated by curcumin. These results provide attractive data for the possible use of curcumin in the management of HPV associated tumors. © 2006 Wiley‐Liss, Inc.
In vivo measurement of the longitudinal relaxation time of arterial blood (T1a) in the mouse using a pulsed arterial spin labeling approach
Authors: Thomas David L. , Lythgoe Mark F. , Gadian David G. , Ordidge Roger J.
Published: March 2006

A novel method for measuring the longitudinal relaxation time of arterial blood (T1a) is presented. Knowledge of T1a is essential for accurately quantifying cerebral perfusion using arterial spin labeling (ASL) techniques. The method is based on the flow‐sensitive alternating inversion recovery (FAIR) pulsed ASL (PASL) approach. We modified the standard FAIR acquisition scheme by incorporating a global saturation pulse at the beginning of the recovery period. With this approach the FAIR tissue signal difference has a simple monoexponential dependence on the recovery time, with T1a as the time constant. Therefore, FAIR measurements performed over a range of recovery times can be fitted to a monoexponential recovery curve and T1a can be calculated directly. This eliminates many of the difficulties associated with the measurement of T1a. Experiments performed in vivo in the mouse at 2.35T produced a mean value of 1.51 s for T1a, consistent with previously published values. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.