bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cryptic epitopes in N‐terminally truncated prion protein are exposed in the full‐length molecule: Dependence of conformation on pH
Authors: Matsunaga Yoichi , Peretz David , Williamson Anthony , Burton Dennis , Mehlhorn Ingrid , Groth Darlene , Cohen Fred E. , Prusiner Stanley B. , Baldwin Michael A. 
Published: August 2002

AbstractPrion diseases are diseases of protein conformation. Structure‐dependent antibodies have been sought to probe conformations of the prion protein (PrP) resulting from environmental changes, such as differences in pH. Despite the absence of such antibodies for full‐length PrP, a recombinant Fab (D13) and a Fab derived from mAb 3F4 showed pH‐dependent reactivity toward epitopes within the N‐terminus of N‐terminally truncated PrP(90–231). Refolding and maintaining this protein at pH ≥5.2 before immobilization on an ELISA plate inhibited reactivity relative to protein exposed to pH ≤4.7. The reactivity was not affected by pH changes after immobilization, showing retention of conformation after binding to the plate surface, although guanidine hydrochloride at 1.5–2 M was able to expose the cryptic epitopes after immobilization at pH ≥5.2. The α‐helical CD spectrum of PrP(90–231) refolded at pH 5.5 was reduced somewhat by these pH changes, with a minor shift toward β‐sheet at pH 4 and then toward coil at pH 2. No covalent changes were caused by the pH differences. This pH dependence suggests titration of an acidic region that might inhibit the N‐terminal epitopes. A similar pH dependence for a monoclonal antibody reactive to the central region identified an acidic region incorporating Glu152 as a significant participant. Proteins 2001;44:110–118. © 2001 Wiley‐Liss, Inc.
Adsorption and degradation of thiazopyr in compost‐amended and non‐amended soils
Authors: Fernández María D , Sánchez‐Brunete Consuelo , Rodríguez Alvaro J , Tadeo José L 
Published: August 2002

AbstractAdsorption and degradation of thiazopyr on two unamended soils and a soil amended annually during 8 years with compost were studied under laboratory conditions and compared with the results obtained on soils amended with fresh sewage sludge compost. The adsorption isotherms fitted the Freundlich equation well and a marked sorption increase was found in amended soils. Degradation data followed first‐order kinetics and thiazopyr had a half‐life of about 75 days at 25 °C and 60% water‐holding capacity of soil. The addition of fresh compost markedly decreased the rate of thiazopyr degradation, whereas the compost mineralised in the field after annual additions had only a small influence. Incubation studies with sterile soils showed a very significant decrease of the degradation rate, indicating that degradation by micro‐organisms was the main pathway of thiazopyr degradation in the soils studied.© 2001 Society of Chemical Industry
Designing herbicide formulation characteristics to maximize efficacy and minimize rice injury in paddy environments
Authors: Cryer Steven A , Mann Richard K , Erhardt‐Zabik Susan , Keeney F Nelson , Handy Paul R 
Published: August 2002

AbstractMathematical descriptors, coupled with experimental observations, are used to quantify differential uptake of an experimental herbicide in Japonica and Indica rice (Oryza sativa, non‐target) and barnyardgrass (Echinochloa crus‐galli, target). Partitioning, degradation, plant uptake and metabolism are described using mass‐balance conservation equations in the form of kinetic approximations. Estimated environmental concentrations, governed by the pesticide formulation, are described using superimposed analytical solutions for the one‐dimensional diffusion equation in spherical coordinates and by a finite difference representation of the two‐dimensional diffusion equation in Cartesian coordinates. Formulation attributes from granules include active ingredient release rates, particle sizes, pesticide loading, and granule spacing. The diffusion model for pesticide transport is coupled with the compartment model to follow the fate and transport of a pesticide from its initial application location to various environmental matrices of interest. Formulation effects, partitioning and degradation in the various environmental matrices, differential plant uptake and metabolism, and dose‐response information for plants are accounted for. This novel model provides a mechanism for selecting formulation delivery systems that optimize specific attributes (such as weed control or the therapeutic index) for risk‐assessment procedures. In this report we describe how this methodology was used to explore the factors affecting herbicide efficacy and to define an optimal release rate for a granule formulation.© 2001 Society of Chemical Industry
METI‐acaricide resistance in Tetranychus urticae does not confer resistance to the naphthoquinones
Authors: Devine Gregor J , Khambay Bhupinder P S 
Published: August 2002

AbstractThe naphthoquinones and the METI group of compounds act on sites associated with mitochondrial respiration, but METI‐resistant strains of two‐spotted spider mite from Japan and the UK exhibited no cross‐resistance to the naphthoquinones. The potential for developing commercial naphthoquinones therefore remains high.© 2001 Society of Chemical Industry
Insecticidal arylalkylbenzhydrolpiperidines: novel inhibitors of voltage‐sensitive sodium and calcium channels in mammalian brain
Authors: Leong Darrell , Bloomquist Jeffrey R , Bempong Jeffrey , Dybas Jane A , Kinne Lyle P , Lyga John W , Marek Francis L , Nicholson Russell A 
Published: August 2002

AbstractUsing preparations derived from whole mouse brain, we have demonstrated that insecticidal arylalkylbenzhydrolpiperidines inhibit the depolarization of synaptoneurosomes as measured by rhodamine 6G fluorescence and block 22Na+ uptake into synaptosomes, when veratridine is used as the activator. These insecticides also have the ability to potently displace the binding of [3H]batrachotoxinin A 20‐α‐benzoate ([3H]BTX‐B) to neuronal sodium channels in a concentration‐dependent manner. The study compounds can be classified as competitive inhibitors of radioligand binding, since they decrease the affinity of [3H]BTX‐B for site 2 without affecting the concentration of sites labelled by this radioligand. Our kinetic analyses revealed that at its IC50, the 4‐carbomethoxyaminobenzylpiperidine analogue reduces the rate of association of [3H]BTX‐B with site 2, whereas higher concentrations were required to accelerate dissociation of the [3H]BTX‐B:sodium channel complex. These results indicate an ability to interact with both non‐activated and persistently activated states of the voltage‐sensitive sodium channel, but higher affinity for the former. Such a profile also implies that inhibition of [3H]BTX‐B binding to site 2 occurs via an allosteric mechanism. In addition, arylalkylbenzhydrolpiperidines interact with presynaptic voltage‐sensitive calcium channels, since we demonstrate that they inhibit increases in [free Ca++] and 45Ca++ uptake when evoked by high KCl concentration in mouse brain synaptosomal preparations. Such effects generally occur at concentrations that are higher than those required to inhibit sodium channels. Blockade of sodium and calcium channels may therefore contribute to the in vivo neurological effects observed in rodents exposed to these insecticides.© 2001 Society of Chemical Industry
PCR‐based detection of sterol demethylation inhibitor‐resistant strains of Penicillium digitatum
Authors: Hamamoto Hiroshi , Hasegawa Koji , Nakaune Ryoji , Lee Young Jin , Akutsu Katsumi , Hibi Tadaaki 
Published: August 2002

AbstractA simple method for detecting sterol demethylation inhibitor (DMI)‐resistant strains of the citrus green mould pathogen, Penicillium digitatum, has been developed. The method involves detection of a tandem repeat of a transcriptional enhancer in the promoter region of PdCYP51, which encodes the target enzyme of DMIs, by PCR, using conidia as template. The presence of the tandem repeat leads to overexpression of this gene and confers DMI resistance to the fungus. We examined the relationship between the presence of the tandem repeat and DMI resistance in 39 strains of P digitatum. The results suggested that the DMI resistance mechanism based on the tandem repeat is common in this fungus. Using this method, the presence of DMI resistance of this fungus can be detected within 5–6 h.© 2001 Society of Chemical Industry
Influence of topsoil tilth and soil moisture status on losses of pesticide to drains from a heavy clay soil
Authors: Brown Colin D , Fryer Chris J , Walker Allan 
Published: August 2002

AbstractTwelve lysimeters with a surface area of 0.5 m2 and a length of 60 cm were taken over mole drains from a Denchworth heavy clay soil and divided into two groups with either a standard agricultural tilth or a finer topsoil tilth. The influence of topsoil tilth on leaching of the herbicide isoproturon and a bromide tracer was evaluated over a winter season. The effect of variations in soil moisture status in the immediate topsoil on leaching of isoproturon, chlorotoluron and linuron was investigated in the following winter season. Here, water inputs were controlled such that lysimeters received 50 mm at a maximum intensity of 2 mm h−1 over a 4‐week period with herbicides applied on day 15. Three treatments received the water either all prior to application, all after application, or evenly spread over the 4‐week period. Leaching losses of the three herbicides were monitored for a subsequent drainage event. Analysis of covariance showed a significant effect of topsoil tilth and total flow on both the maximum concentrations (P  = 0.034) and total losses (P  = 0.012) of isoproturon in drainflow. Both concentrations and losses were c 35% smaller from lysimeters with the finer tilth. However, generation of the fine tilth in the field was restricted by a wet autumn and this is not considered a reliable management option for reducing pesticide losses from heavy clay soils. In the second experiment, variation in soil moisture content prior to and after application did not have any significant effect (P < 0.05) upon subsequent losses of the three herbicides to drains.© 2001 Society of Chemical Industry
Evidence for oil‐induced oxidative stress to larvae of the lightbrown apple moth, Epiphyas postvittana Walker (Lepidoptera: Tortricidae)
Authors: Taverner Peter D , Bailey Peter T , Roush Richard T 
Published: August 2002

AbstractFor the purpose of understanding better the mode of action of alkanes on insects, the relationship between mortality, weight loss in oxygen enriched atmospheres and dietary antioxidants was examined using an alkane, C15 Ampol CPD and a spray oil, C23 DC‐Tron NR, on lightbrown apple moth, Epiphyas postvittana Walker, (LBAM). The results showed that the surfactant blend used in CPD was an insignificant contributor to the overall toxicity of dilute oil/water emulsions. Higher weight loss occurred in CPD‐dipped larvae than C23 DC‐Tron NR‐dipped larvae, which suggests that alkanes disrupt tracheal waxes and render insects more prone to desiccation. High levels of oxygen increased the toxicity of CPD to LBAM larvae. In addition, dietary supplements of anti‐oxidant, α‐tocopherol, fed to LBAM larvae were successful in reducing the toxicity of CPD. These results suggest that the alkane may contribute to oxidative injury. The potential role of oil‐induced oxidative stress in acute and chronic toxicity in insects is discussed.© 2002 Society of Chemical Industry
A type‐II β‐turn, proline‐containing, cyclic pentapeptide as a building block for the construction of models of the cleavage site of pro‐oxytocin
Authors: Dettin Monica , Falcigno Lucia , Campanile Tiziano , Scarinci Claudia , D'Auria Gabriella , Cusin Marina , Paolillo Livio , Di Bello Carlo 
Published: August 2002

AbstractPrevious studies have indicated that proteolytic activation of pro‐hormones and pro‐proteins occurs most frequently at the level of basic amino acids arranged in doublets and that the dibasic sites are situated in or next to β‐turns. Investigations utilizing synthetic peptides reproducing the N‐terminal processing domain of pro‐oxytocin‐neurophysin have suggested a close relationship between the secondary structure of the cleavage locus and enzyme recognition, the minimal recognized sequence being the ‐Pro‐Leu‐Gly‐Gly‐Lys‐Arg‐Ala‐Val‐Leu‐ segment of the native precursor. NMR investigations and energy minimization studies have demonstrated that this sequence is organized in two type‐II β‐turns involving the ‐Pro‐Leu‐Gly‐Gly‐ and ‐Lys‐Arg‐Ala‐Val‐ sequences. To further strengthen the above reported hypothesis and to study the role of turn subtypes, a new proline containing cyclic substrate of the processing enzyme, in which the N‐terminal side that comes before the Lys‐Arg pair is constrained to adopt a type‐II β‐turn, has been synthesized. The presence of a type‐II β‐turn structure in this cyclic peptide model has been demonstrated by a combined NMR, CD and FT‐IR absorption investigation. A preliminary study shows that PC1 is able to recognize and process our constrained substrate. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Representative values of thermal actions for concrete bridges
Authors: Soukhov Dmitri 
Published: August 2002

AbstractThe pre‐standard ENV 1991‐2‐5 Thermal Actions was concluded in 1996 and deals with the thermal actions induced in the structures due to climatic effects (air temperature, solar radiation). These climatic conditions cause a non‐linear temperature profile through the depth of the bridge deck. This profile can be subdivided into three parts which are called ‘thermal actions’: bridge effective temperature, linear temperature difference, non‐linear part. For concrete bridges the first two parts play the most important role. According to pre‐ standards ENV 1991‐1 Basis of Design thermal actions are defined as variable actions and following representative values have to be determined: –characteristic value, with return period of 50 years; –infrequent value, with return period of one year; –frequent value, with return period of two weeks; –quasi‐permanent value Three groups of bridge cross sections are investigated: box girders, T‐girders, slabs.The climatic data were obtained from the meteorological station Giessen (Hessen, Germany). This station located in the centre of Germany and Europe and can be considered as a representative place for middle Europe. The record period is from 1981 to 1990.To exclude the problem of autocorrelation the three‐day maximum of climatic effects and extreme value distribution type III are used for statistical analysis. Then the representative values of climatic effects are calculated.For calculation of temperature profile the one‐dimensional heat flow model through concrete bridge deck is used. This model runs off for four different representative values of climatic effects. Afterwards four representative values for uniform temperature component and for linear temperature differences are obtained. The reduction coefficients Ψ are also calculated. The characteristic values of thermal actions are included in the document ENV 1991‐2‐5 Thermal Actions and the Ψ coefficients are included in the document ENV 1991‐3 Traffic Loads on Bridges.
Recent European research advances in snow loading and their possible implementation in the Eurocodes
Authors: Del Corso R , Formichi P , Stiefel U 
Published: August 2002

AbstractThe main results of a prenormative research programme on snow loads, sponsored in 1996 by the European Commission, are presented. The research work, to which eight European scientific institutions took part, addressed the determination of ground and roof snow loads for ultimate and serviceability limit states verifications.European regulations regarding snow loads are currently in the process of being updated, as Eurocode 1 is being converted from ENV 1991‐2‐3 to EN 1991‐1‐3. Many of the research results have been considered during the conversion process, but their direct introduction into the new code has raised some problems, since such results are not yet well established. The use of the research results for normative purposes is discussed and some open problems are presented.
Obtaining confidence intervals for Cpk using percentiles of the distribution of Ĉp
Authors: Hoffman Lorrie L. 
Published: August 2002

AbstractĈpk is used as an estimate of process capability and can reflect performance degradation due to both shifts in the process mean and variability. Exact upper and lower confidence limits for the actual parameter value are elusive. Objections to existing estimators focus on two areas: the difficulty of executing the needed computations and the excessive widths of those confidence bounds. The CPE estimator (so called since it relies on Ĉp ) which we derive in this paper is formed by simply multiplying Ĉpk by a value from the inverse chi‐square distribution. A PASCAL computer program is supplied which generates those percentiles. Our CPE is compared via simulation to other estimators and is shown to be the preferred selection in most cases by providing the requisite probability coverage and narrow interval widths. Copyright © 2001 John Wiley & Sons, Ltd.
Identification and fine tuning of closed‐loop processes under discrete EWMA and PI adjustments
Authors: Pan Rong , del Castillo Enrique 
Published: August 2002

AbstractConventional process identification techniques of a open‐loop process use the cross‐correlation function between historical values of the process input and of the process output. If the process is operated under a linear feedback controller, however, the cross‐correlation function has no information on the process transfer function because of the linear dependency of the process input on the output. In this paper, several circumstances where a closed‐loop system can be identified by the autocorrelation function of the output are discussed. It is assumed that a proportional integral controller with known parameters is acting on the process while the output data were collected. The disturbance is assumed to be a member of a simple yet useful family of stochastic models, which is able to represent drift. It is shown that, with these general assumptions, it is possible to identify some dynamic process models commonly encountered in manufacturing. After identification, our approach suggests to tune the controller to a near‐optimal setting according to a well‐known performance criterion. Copyright © 2001 John Wiley & Sons, Ltd.
Theoretical study of metal ligand aromatic cation–π interactions of [Co(NH3)6]3+ with benzene
Authors: Žmirić Aleksandra , Milčić Miloš , Zarić Snežana D. 
Published: August 2002

AbstractIn this work, density functional theory calculations on geometries and energies of all possible conformers of the [Co(NH3)6]3+–C6H6 cation–π complex are described. The calculations show that stationary points are several η2 and the η3 structures. The most stable η3 structure has bonding energy, after basis set superposition error correction, of 32.18 kcal/mol. The energies of η3 structures are similar; also, the energies of η2 structures are similar while the difference in energy between η3 and the η2 structures is about 2 kcal/mol. This indicates a possibility for various orientations of the benzene ring with respect to interacting ligands in the case of metal ligand aromatic cation–π (MLACπ) interactions and a possibility for the existence of these interactions in different molecular systems. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Semiempirical INDO/S calculations on the absorption spectrum of mono‐ and trinuclear vanadium(II) complexes
Authors: Niedwieski Antonio Carlos , Soares Jaísa Fernandes , Jeffery Leigh George , Nunes Fábio Souza , Da Motta Neto Joaquim Delphino 
Published: August 2002

AbstractThis work is concerned with prospective starting materials for the synthesis of larger molecules used as functional models of the substrate binding and reducing site of the vanadium nitrogenase. It is well known that the mononuclear adduct of vanadium(II) chloride with N,N,N′,N′‐tetramethylethylenediamine, henceforth referred to as [VCl2(tmeda)2], is a good starting material for the synthesis of trinuclear vanadium complexes. We now report the results of semiempirical calculations on the spectroscopy of [VCl2(tmeda)2] using the intermediate neglect of differential overlap (INDO) method. For the mononuclear complex, the ground state was calculated to be a quartet, about 45 kcal/mol below the doublet. For the positively charged trinuclear vanadium complex, [V3(μ‐Cl)3(μ3‐Cl)2(tmeda)3]+, the ground state was calculated to be a decatet, about 47 kcal/mol below the octet. For both complexes the frontier orbitals are dominated by the vanadium 3d manifold, and accordingly the electronic spectra are dominated by d‐d* excitations within this manifold. The INDO/S‐calculated spectra are in good agreement with the observed UV‐visible spectra in both cases. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 245–251, 2002
Exploiting the interdependence of maximum entropy parameters in eigenvalue problems
Authors: Bandyopadhyay K. , Bhattacharyya K. , Bhattacharya A. K. 
Published: August 2002

AbstractWe exploit the interrelation among the parameters embedded in the maximum entropy ansatz to develop a scheme for obtaining accurate estimates of the ground‐state energy and wave function of systems for which the potential is represented by a rational function. Our scheme reduces an N‐parameter optimization problem to a two‐parameter one, leading to considerable simplification of the prevalent strategy. An indirect route for the study of excited states is also sketched. Test calculations on hydrogenic systems subject to strong or superstrong radial magnetic fields with and without electric field reveal the advantages of our approach. Additional studies on 1‐D anharmonic oscillators affirm its workability and generality. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Theoretical studies on the structures and isomerization of methylene lithium‐chlorosilylenoid H2CSiLiCl
Authors: Feng Shengyu , Feng Dacheng , Li Meijiang , Zhou Yufang 
Published: August 2002

AbstractThe methylene lithium‐chlorosilylenoid H2CSiLiCl was studied with ab initio calculations at the G2(MP2) level. Its four equilibrium structures, p‐complex, three‐membered ring, σ complex and silene, and three isomerization transition states were located. The calculations show that the nonplanar p‐complex structure is the lowest in energy among four equilibrium structures of H2CSiLiCl and should be experimentally detectable. The silene and σ complex structures with high energies are unstable and easy to isomerize to the most stable p‐complex structure via three‐membered ring one. Also, the geometric characteristics and bonding properties of various structures were analyzed and discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Features of the fluorine‐substituted acetaldehydes dynamics in the low‐lying electronic states: Quantum mechanical study of the CHF2CHO molecule lowest excited singlet state
Authors: Bataev Vadim A. , Dolgov Eugeniy K. , Abramenkov Alexandr V. , Pupyshev Vladimir I. , Godunov Igor A. 
Published: August 2002

AbstractThe potential energy surface (PES) for the CHF2CHO molecule in the excited S1 state is calculated by the CASSCF method. The features of the 1‐ and 2‐D cross‐sections of PES are considered in comparison with those of the relative molecules. The vibrational frequencies are calculated in harmonic approximation and the vibrational energy levels for the inversion motion of the carbonyl fragment CCHaO and for the torsion motion of the CHF2‐top are calculated in anharmonic approximation by the 1‐ and 2‐D variational methods. The calculated data are compared with the experimental ones. The problems of the experimental data interpretation are considered. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002