bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atomic Properties of Amino Acids: Computed Atom Types as a Guide for Future Force‐Field Design
Authors: Popelier Paul L. A. , Aicken Fiona M. 
Published: August 2003

AbstractThe quantum chemical topology (QCT) is able to propose atom types by direct computation rather than by chemical intuition. In previous work, molecular electron densities of 20 amino acids and smaller derived molecules were partitioned into a set of 760 topological atoms. Each atom was characterised by seven atomic properties and subjected to cluster analysis element by element, that is, C, H, O, N, and S. From the respective dendrograms, 21 carbon atom types were distinguished, 7 hydrogen, 2 nitrogen, 6 oxygen, and 6 sulfur atom types. Herein, we contrast the QCT atom types with those of the assisted model building with energy refinement (AMBER) force field. We conclude that in spite of fair agreement between QCT and AMBER atom types, the latter are sometimes underdifferentiated and sometimes overdifferentiated. In summary, we suggest that QCT is a useful guide in designing new force fields or improving existing ones. The computational origin of QCT atom types makes their determination unbiased compared to atom type determination by chemical intuition and a priori assumptions. We provide a list of specific recommendations.
PRICE: primitive centred schemes for hyperbolic systems
Authors: Toro E. F. , Siviglia A. 
Published: August 2003

AbstractWe present first‐ and higher‐order non‐oscillatory primitive (PRI) centred (CE) numerical schemes for solving systems of hyperbolic partial differential equations written in primitive (or non‐conservative) form. Non‐conservative systems arise in a variety of fields of application and they are adopted in that form for numerical convenience, or more importantly, because they do not posses a known conservative form; in the latter case there is no option but to apply non‐conservative methods. In addition we have chosen a centred, as distinct from upwind, philosophy. This is because the systems we are ultimately interested in (e.g. mud flows, multiphase flows) are exceedingly complicated and the eigenstructure is difficult, or very costly or simply impossible to obtain. We derive six new basic schemes and then we study two ways of extending the most successful of these to produce second‐order non‐oscillatory methods. We have used the MUSCL‐Hancock and the ADER approaches. In the ADER approach we have used two ways of dealing with linear reconstructions so as to avoid spurious oscillations: the ADER TVD scheme and ADER with ENO reconstruction. Extensive numerical experiments suggest that all the schemes are very satisfactory, with the ADER/ENO scheme being perhaps the most promising, first for dealing with source terms and secondly, because higher‐order extensions (greater than two) are possible. Work currently in progress includes the application of some of these ideas to solve the mud flow equations. The schemes presented are generic and can be applied to any hyperbolic system in non‐conservative form and for which solutions include smooth parts, contact discontinuities and weak shocks. The advantage of the schemes presented over upwind‐based methods is simplicity and efficiency, and will be fully realized for hyperbolic systems in which the provision of upwind information is very costly or is not available. Copyright © 2003 John Wiley & Sons, Ltd.
Methods for implementing the stream boundary condition in DSMC computations
Authors: Lilley Charles R. , Macrossan Michael N. 
Published: August 2003

AbstractIn the direct simulation Monte‐Carlo (DSMC) method for simulating rarefied gas flows, the velocities of simulator particles that cross a simulation boundary and enter the simulation space are typically generated using the acceptance–rejection procedure that samples the velocities from a truncated theoretical velocity distribution that excludes low and high velocities. This paper analyses an alternative technique, where the velocities of entering particles are obtained by extending the simulation procedures to a region adjacent to the simulation space, and considering the movement of particles generated within that region during the simulation time step. The alternative method may be considered as a form of acceptance–rejection procedure, and permits the generation of all possible velocities, although the population of high velocities is depleted with respect to the theoretical distribution. Nevertheless, this is an improvement over the standard acceptance–rejection method. Previous implementations of the alternative method gave a number flux lower than the theoretical number required. Two methods for obtaining the correct number flux are presented. For upstream boundaries in high‐speed flows, the alternative method is more computationally efficient than the acceptance–rejection method. However, for downstream boundaries, the alternative method is extremely inefficient. The alternative method, with the correct theoretical number flux, should therefore be used in DSMC computations in favour of the acceptance–rejection method for upstream boundaries in high‐speed flows. Copyright © 2003 John Wiley & Sons, Ltd.
Preliminary study of L‐lysine production by Bacillus species using various agricultural by‐products
Authors: Ekwealor Ikechukwu A. , Ebele Orafu A. 
Published: August 2003

AbstractThe production of lysine by Bacillus megaterium SP‐14 and Bacillus circulans Tx‐22 using agricultural by‐products as carbon and nitrogen sources was assessed. Among the carbon substrates used were potato, sorghum, plantain, millet, yam, cassava, and corn starches, while the nitrogen sources include cowpea, bambara‐nut, cotton seed, groundnut, soybean, and blood meals. The effect of natural nitrogen sources (1.0% w/v) and synthetic nitrogen source (4.0% w/v (NH4)2SO4) on lysine production by the Bacillus strains showed that natural nitrogen sources gave better lysine yields.
Sensory and rheological properties of Polish commercial mayonnaise
Authors: Juszczak Lesław , Fortuna Teresa , Kośla Aneta 
Published: August 2003

AbstractSensory and rheological analyses were performed to compare seven commercial mayonnaises having various fat contents and containing, or not, thickening and stabilizing agents. It was found that mayonnaise samples differed in their sensory and rheological properties. The samples with a higher fat content scored higher in sensory analysis than the low‐fat ones. The mayonnaises studied showed non‐Newtonian, pseudoplastic flow with yield stress and thixotropy. All mayonnaises, although to a different degree, exhibited a decrease in the apparent viscosity at constant shear. The mayonnaise samples which contained thickeners and stabilizers had a greater rheological stability.
Chemical composition and antioxidant test of free and glycosidically bound volatile compounds of savory (Satureja montana L. subsp. montana) from Croatia
Authors: Radonic Ani , Milos Mladen 
Published: August 2003

AbstractThe evaluation of antioxidant power of glycosidically bound volatile aglycones from savory shows that these compounds possess antioxidative activity comparable to that of the essential oil, but less effective compared to the well‐known antioxidant butylated hydroxytoluene (BHT) and α‐tocopherol. Thus, since the glycosides are able to release their aglycones by enzymatic hydrolysis, they could be considered as possible precursors of antioxidant substances in savory.
Determination of water‐soluble vitamins in soft drinks and vitamin supplements using capillary electrophoresis
Authors: Schreiner Matthias , Razzazi Ebrahim , Luf Wolfgang 
Published: August 2003

AbstractA method for the determination of six water‐soluble vitamins based on capillary electrophoresis (CE) operated in micellar mode was developed. Thiamine hydrochloride (vitamin B1( riboflavin (vitamin B2( pyridoxine hydrochloride (vitamin B6( pantothenic acid (vitamin B5( nicotinamide (vitamin B3( and cobalamin (Vitamin B12) could be separated in a single run. All CE parameters such as buffer composition and operation temperature were optimized in order to achieve better separation. Relative standard deviations (RSDs) of the described method ranged from 1.08 to 3.68% (intra‐day precision) and 1.26 to 3.35% (inter‐day precision). The method was then used for measuring various soft drinks and vitamin supplements directly without any step of sample cleanup. The determination of niacin was successful for all samples tested, reaching recoveries near 100%. Riboflavin and pyridoxine were quantified successfully in some but not all samples. Therefore, an evaluation on a case‐by‐case basis is mandatory. When applicable, this method provides a fast, accurate, simple, and inexpensive way to quantify selected vitamins, and is therefore well suited for routine analysis in soft drink industry.
Physicochemical, rheological, and organoleptic characteristics of wheat‐fenugreek supplemented blends
Authors: Hooda Shalini , Jood Sudesh 
Published: August 2003

AbstractThe effect of blending of fenugreek (raw, soaked, and germinated) flour (Trigonella faenum graecum) from 5 to 20% in wheat flour on the rheological and sensory evaluation of bread, biscuit, noodle, and macroni was studied. Farinograph water absorption, dough development time, mixing tolerance index, and dough stability increased significantly with increased amount of fenugreek flour. Incorporation of fenugreek flour in wheat flour increased the protein and fat contents of blends but decreased the gluten contents. Among the supplemented blends, blends containing germinated fenugreek flour had higher protein contents (13.83–16.30%) up to 20%. Overall acceptability scores of bread, biscuit, noodles, and macroni were found highly acceptable up to 15, 10, and 20% levels, respectively.
Sample size calculations for population‐ and family‐based case‐control association studies on marker genotypes
Authors: Pfeiffer Ruth M. , Gail Mitchell H. 
Published: August 2003

AbstractMost previous sample size calculations for case‐control studies to detect genetic associations with disease assumed that the disease gene locus is known, whereas, in fact, markers are used. We calculated sample sizes for unmatched case‐control and sibling case‐control studies to detect an association between a biallelic marker and a disease governed by a putative biallelic disease locus. Required sample sizes increase with increasing discrepancy between the marker and disease allele frequencies, and with less‐than‐maximal linkage disequilibrium between the marker and disease alleles. Qualitatively similar results were found for studies of parent offspring triads based on the transmission disequilibrium test (Abel and Müller‐Myhsok, 1998, Am. J. Hum. Genet. 63:664–667; Tu and Whittemore, 1999, Am. J. Hum. Genet. 64:641–649). We also studied other factors affecting required sample size, including attributable risk for the disease allele, inheritance mechanism, disease prevalence, and for sibling case‐control designs, extragenetic familial aggregation of disease and recombination. The large sample‐size requirements represent a formidable challenge to studies of this type. Genet Epidemiol 25:136–148, 2003. Published 2003 Wiley‐Liss, Inc.
Family‐based analysis of MSX1 haplotypes for association with oral clefts
Authors: Fallin M. Daniele , Hetmanski Jacqueline B. , Park Jiwan , Scott Alan F. , Ingersoll Roxann , Fuernkranz Hans A. , McIntosh Iain , Beaty Terri H. 
Published: August 2003

AbstractOral clefts, one of the most common forms of birth defects, are considered to be of complex etiology, including both genetic and environmental causes. To date, however, no particular genetic cause has been confirmed for isolated, nonsyndromic oral clefts. Previous case‐control and family‐based association studies reported an association between an intronic CA repeat of the MSX1 gene and risk for oral clefts. In this study, we identify eight single‐nucleotide polymorphisms (SNPs) in the MSX1 gene, and present genotype results for these SNPs in a set of 206 oral cleft cases and their parents. We performed single‐marker and haplotype‐based transmission disequilibrium tests (TDTs), and tested for evidence of interaction between MSX1 haplotypes and exposure to maternal smoking in the first trimester, using a case‐only approach. The haplotype TDT analyses further implicate this gene, or region, in controlling the risk for oral clefts, particularly for cleft palate. In addition, case‐only haplotype analyses suggest an interaction between variation in the MSX1 gene and exposure to maternal smoking. This study encourages further focus on the MSX1 gene region to ultimately determine specific variants predisposing to oral clefts. Genet Epidemiol 25:168–175, 2003. © 2003 Wiley‐Liss, Inc.
New developments in the employee–organization relationship
Authors: Shore Lynn M. , Coyle‐Shapiro Jacqueline A‐M. 
Published: August 2003

AbstractGreater understanding of the relationship between an employee and his/her employing organization has been the goal of organizational behaviour scholars for decades. Many questions have remained unanswered, and with this view in mind, the articles in this special issue examined the employee–organization relationship (EOR) from multiple perspectives. These articles provided considerable support for social exchange as a basis for understanding the EOR in diverse cultures, for different work arrangements and at the individual, dyadic, and organizational levels of analysis. Furthermore, several articles provided empirical evidence as to the boundary conditions of social exchange as a framework for understanding the EOR. Both conceptual and empirical articles examined distinctions and similarities among exchange related constructs. This special issue extends current thinking on the employment relationship by examining the role of culture and sense making in the formation of the EOR; the value of cognitive processes in the revision and evaluation of the EOR and; the contribution of the employer's perspective to the EOR. Future research should build on this work by focusing more attention on aspects of the context as well as individual differences that may influence EORs. Finally, the employer's perspective warrants greater attention conceptually and empirically to further our understanding of the EOR as a two‐way exchange. Copyright © 2003 John Wiley & Sons, Ltd.
Java implementation of policy‐based bandwidth management
Authors: Jha S. , Hassan M. 
Published: August 2003

AbstractWe describe a Java implementation of a policy based bandwidth management system using the standard policy protocols and an interface to the Linux Diffserv implementation. The useful features, such as extensibility and object orientation, of the Java implementation is illustrated by directly referring to the relevant programming codes. Through two practical experiments, we demonstrate the capability of our implementation in supporting policy‐based dynamic resource allocations in enterprise networks. Copyright © 2003 John Wiley &Sons, Ltd.
Controlling unresponsive connections in an active network architecture
Authors: Prabhavalkar Niraj , Parashar Manish 
Published: August 2003

AbstractThis paper presents the design, implementation and evaluation of Limiting Greedy Connections (LGC), an active mechanism for controlling unresponsive connections and minimizing the degradation in network performance caused by bandwidth‐greedy applications. The primary objectives of the LGC mechanism are to limit the impact of greedy connections on a congested node, to keep a loose upper bound on the packet queue occupancy at the intermediate nodes of the network and to minimize packet loss. The LGC mechanism is evaluated for a variety of network topologies, transmitting sources and node queue parameters, using a Java‐based active network testbed. Copyright © 2003 John Wiley &Sons, Ltd.
Estimation of a pKa for Protonated Dimethoxycarbene
Authors: Guthrie J. P. , More O'Ferrall R. A. , O'Donoghue A. C. , Waghorne W. E. , Zrinski I. 
Published: August 2003

AbstractA pKa is estimated for the protonation of dimethoxycarbene based on the relationship pKa = pKR −pKH2O, where KH2O and KR are equilibrium constants for hydration of the carbene and reaction of the dimethoxymethyl carbocation with water to form dimethoxymethanol, respectively. A value of pKa = 15.5 in aqueous solution is derived based on pKR = −5.7 for the carbocation and an estimate of pKH2O = −21.2 based on a heat of formation of the carbene ΔH°f = −38.8 ± 2 kcal mol−1, calculated at the G3 level in the gas phase. This value for the pKa compares satisfactorily with pKa = 11 inferred from the dependence of experimental rate constants for reaction of the carbene with alcohols and acetic acid upon the pKa of the oxygen acid in acetonitrile, taking account of the difference in solvents for the calculated and measured values. The calculated heat of formation of dimethoxycarbene in the gas phase is compared with an experimental value of −52.6 kcal mol−1 based on photoacoustic measurements of the heat of reaction of the carbene with methanol solvent to form trimethyl orthoformate. Reanalysis of the experimental data using a heat of solution of trimethyl orthoformate in methanol measured in this work suggests that the discrepancy arises in part from a difference in the heat of reaction of the carbene with methanol in solution and in the gas phase and partly (although less certainly) from a relatively high heat of solution of the carbene in methanol. Copyright © 2003 John Wiley & Sons, Ltd.
Protective effect of fenugreek (Trigonella foenum graecum) seeds in experimental ethanol toxicity
Authors: Thirunavukkarasu V. , Anuradha C. V. , Viswanathan P. 
Published: August 2003

AbstractThe study investigates the effect of aqueous extract of fenugreek seeds (Trigonella foenum graecum) on lipid peroxidation and antioxidant status in experimental ethanol toxicity in rats. The ability of the seed extract to prevent iron‐induced lipid peroxidation in vitro was also investigated. Ethanol feeding for 60 days resulted in signiﬁcant increases in the activities of serum aspartate transaminase, alanine transaminase and alkaline phosphatase. The levels of serum lipid hydroperoxides and thiobarbituric acid reactive substances in liver and brain were also signiﬁcantly elevated. Signiﬁcantly lower activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S‐transferase and glutathione reductase were observed in liver and brain accompanied by depletion in glutathione, ascorbic acid and α‐tocopherol concentrations. Activity of Ca2+ ATPase in brain was signiﬁcantly lowered.Simultaneous administration of aqueous extract of fenugreek seeds with ethanol prevented the enzymatic leakage and the rise in lipid peroxidation and enhanced the antioxidant potential. The seeds exhibited appreciable antioxidant property in vitro which was comparable with that of reduced glutathione and α‐tocopherol. Further, histopathological examination of liver and brain revealed that, aqueous extract of fenugreek seeds could offer a signiﬁcant protection against ethanol toxicity. Copyright © 2003 John Wiley & Sons, Ltd.
Four glycosides from the leaves of Abeliophyllum distichum with inhibitory effects on angiotensin converting enzyme
Authors: Oh Hyuncheol , Kang Dae‐Gill , Kwon Tae‐Oh , Jang Kyu Kwan , Chai Kyu‐Yun , Yun Young‐Gab , Chung Hun‐Taeg , Lee Ho‐Sub 
Published: August 2003

AbstractThe bioassay‐guided fractionation of the n‐BuOH extract of Abeliophyllum distichum afforded acteoside (1), isoacteoside (2), rutin (3), and hirsutrin (4). Compounds 1–3 moderately inhibited the angiotensin I converting enzyme activity in a dose‐dependent manner. Compounds 1–3 showed the 50% inhibitory concentration values of 228 µg/mL, 290 µg/mL, and 278 µg/mL, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Interaction of some traditional plant extracts with uterine oestrogen or progestin receptors
Authors: Benie T. , Thieulant M.‐L. 
Published: August 2003

AbstractPrevious work has demonstrated that stem bark extracts of Combretodendron macrocarpum (Barringtoniaceae), Cola nitida (Sterculiaceae), Afrormosia laxiﬂora and Pterocarpus erinaceus (Fabaceae) blocked the oestrus cycle of female rats through antigonadotropic activity. Moreover, a study of the plant substances responsible for these effects revealed the presence of phyto‐anti‐oestrogens in these plant extracts. In order to explain the mechanism by which these substances exert their antifertility actions, the interaction of the plant extract with oestrogen and progesterone receptors was studied. All crude extracts exerted inhibition of (3H)‐oestradiol or (3H)‐Organon binding to their respective receptors but their relative afﬁnities were much lower than those of oestradiol or progesterone. Respective efﬁciencies of plant extracts in competing for the oestrogen receptor were as follows: A. laxiﬂora > P. erinaceus > C. macrocarpum > C. nitida. The efﬁciency order of competition for the progestin receptor was different to that of oestrogen. The most potent competitor was C. macrocarpum extract, followed by P. erinaceus, C. nitida and A. laxiﬂora. Moreover, the interaction between oestradiol and plant extracts with the oestrogen receptor was determined to be competitive only for C. macrocarpum and A. laxiﬂora, whereas all compounds produced a competitive inhibition on the progestin receptor binding. These results suggest that the plant extract binding site was the same site as for the steroid. These results suggest also that crude plant extracts may interfere with natural oestrogen and/or progestagen in vivo by binding to steroid receptors. Copyright © 2003 John Wiley & Sons, Ltd.
Polyphenols of Melaleuca quinquenervia leaves – pharmacological studies of grandinin
Authors: Moharram F. A. , Marzouk M. S. , El‐Toumy S. A. A. , Ahmed A. A. E. , Aboutabl E. A. 
Published: August 2003

AbstractFour polyphenolic acid derivatives and three ellagitannins were isolated from the leaves of Melaleuca quinquenervia (Clav.) S. T. Blake for the ﬁrst time. Their structures were elucidated as gallic acid (1), ellagic acid (2), 3‐O‐methylellagic acid (3), 3,4,3′‐tri‐O‐methylellagic acid (4), 2,3‐O‐hexahydroxydiphenoyl‐(α/β)‐D‐4C1‐glucopyranose (5), castalin (6) and grandinin (7) on the basis of chemical, mass spectrometric (‐ve ESI‐MS) and spectroscopic (UV, 1H‐, 13C NMR, 1H,1H‐, 1H,13C‐COSY, 1H,1H‐TOCSY and HMBC) analyses. Grandinin (the major compound) showed radical scavenging properties by its reaction with 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical [EC50 = 4.3 ± 0.3 µg mL−1]. It was found to be relatively nontoxic in mice [LD50 = 316 mg Kg−1 b.wt.]. It exhibited a signiﬁcant dose‐dependent (35–70 mg Kg−1) hypoglycemic effect by signiﬁc‐antly reducing blood glucose level in basal condition and after heavy glucose load in normal mice. Moreover, it reduced the elevated blood glucose level in STZ‐induced diabetic mice. In addition, grandinin reduced the elevated blood urea nitrogen and serum lipid peroxides in STZ‐induced diabetic mice. Copyright © 2003 John Wiley & Sons, Ltd.