bluuebunny/crossref_metadata_2025 huggingface dataset:
Highest efficiency rapid thermal processed multicrystalline silicon solar cells
Authors: Noël S. , Lautenschlager H. , Muller J. C.
Published: January 2005

The formation of pn junctions and surface passivation by rapid thermal processing is being proved as a new and competitive method for silicon solar cell production. As the main process mechanisms are enhanced, the total process time at high temperature can be kept in the minute range, for the realization of emitter, back surface field (BSF) and surface passivation. In this work, we demonstrate for the first time that this knowledge, avoiding any in‐situ annealing step acquired on the sc‐Si, can also be applied on industrial mc‐Si (Polix©) without bulk degradation, leading to a record conversion efficiency of 16·7%. Copyright © 2001 John Wiley & Sons, Ltd.
Photovoltaic market and costs forecast based on a demand elasticity model
Authors: Luque Antonio
Published: January 2005

A model of the increase in sales of photovoltaic modules is presented, based on coupling the learning curve and the demand elasticity equations. The model, solved for constant demand elasticity, shows good agreement with past sales data, better than any exponential growth curve. We have used this model, properly refined, to extrapolate the market evolution for the next half century, and we have compared the results with the goals of the RIGES scenario for CO2abatement, presented to the Rio Conference of 1992. The model predicts a very fast growth that will slow down when a certain level of annual sales is reached. It is uncertain if the size of the photovoltaics industry will reach a level with a major environmental impact. New technological findings may be the fastest way to reach the environmental goals, but changes of the present marketing scheme or electricity price increases may also lead to the desired environmental impact in the first half of the century.

Se presenta un modelo basado en el acoplamiento de las ecuaciones de la curva de aprendizaje y la curva de elasticidad de la demanda. El modelo, resuelto para elasticidad de la demanda constante, muestra un buen acuerdo con las ventas pasadas, mejor que cualquier exponencial. Hemos usado este modelo, refinado adecuadamente, para extrapolar la evolución del mercado al próximo medio siglo y hemos comparado los resultados con los objetivos del escenario RIGES para reducción del CO2presentados en la cumbre de Río de 1992. El modelo predice un crecimiento muy rápido que se ralentizará cuando se alcance un cierto nivel de ventas anuales. Aunque este negocio ha de llegar a ser muy grande, no es seguro si alcanzará un impacto ambiental significativo. Nuevos hallazgos tecnológicos pueden constituir el medio más rápido para alcanzar los objetivos ambientales, pero cambios en el actual modo de comercialización, o incrementos del precio de la electricidad pueden también conducir a alcanzar los impactos ambientales significativos deseados en la primera mitad del siglo. Copyright © 2001 John Wiley & Sons, Ltd.
Limiting photovoltaic monochromatic light conversion efficiency
Authors: Green Martin A.
Published: January 2005

Notwithstanding the relatively low energy conversion efficiencies typical of standard solar photovoltaic systems, photovoltaic cells are shown, in principle, to be capable of converting well‐collimated monochromatic light at efficiencies arbitrarily close to 100%. To approach such efficiencies, radiative recombination must be the main recombination process within the cell. The intensity of the monochromatic light must be high, and the cell should be designed so that it does not absorb or emit light outside the range of angles and wavelengths required to accept the incident monochromatic light. The thermodynamic basis of such high efficiency is also briefly discussed. Copyright © 2001 John Wiley & Sons, Ltd.
A photovoltaic solar home system dissemination model
Authors: Barua Dipal C. , Urmee Tania P. , Kumar S. , Bhattacharya S. C.
Published: January 2005

Dissemination of photovoltaic (PV) electricity generation systems in developing countries faces a multitude of financial, technical, institutional and policy barriers. Demonstration of the system by appropriately selecting sites and users, providing an appropriate financial mechanism and technical support, and creating awareness among users can serve to trigger significant spontaneous propagation of PV systems. A strategy/approach adopted in promoting dissemination of solar home systems (SHSs) in Bangladesh is described, together with details of the methodology, including the planning, maintenance and training efforts undertaken. Progress in propagation of PV systems has been monitored since the installation of the demonstration systems; the success of the approach adopted can be gauged by the fact that since the installation of ten demonstration units in the selected area, a tremendous increase in the sale of PV SHSs has been observed. Copyright © 2001 John Wiley & Sons, Ltd.
Bulk resistivity optimization for low‐bulk‐lifetime silicon solar cells
Authors: Brody Jed , Rohatgi Ajeet , Yelundur Vijay
Published: January 2005

Guidelines are presented which are designed to achieve planar solar cell efficiencies as high as 17.5% using existing fabrication technologies and silicon substrates with lifetimes as low as 20 μs. Device simulations are performed to elucidate the need and impact of base doping optimization for different back‐surface passivation schemes, cell thicknesses, emitter profiles, and degrees of dopant–defect interaction. Results indicate that optimal resistivity is a function of back‐surface passivation, with the aluminum back‐surface field (BSF) requiring the highest resistivity, the oxide/nitride stack passivation excelling at an intermediate resistivity, and the ohmic contact needing the lowest resistivity. A comparison of simulated 300 and 100 μm cells shows that thinner cells magnify the differences in optimal resistivity for the three back‐surface passivation schemes. A lifetime model is used to account for dopant–defect interaction that can lower bulk lifetime at higher doping levels. It is demonstrated that cell efficiency decreases and optimal resistivity increases at higher levels of dopant–defect interaction. Simulated devices with an optimized base doping showed an efficiency improvement of as much as 2% (absolute) compared with identical devices with a typical base doping level (1.6 or 1.8 Ω cm) and bulk lifetime of 20 μs. Copyright © 2001 John Wiley & Sons, Ltd.
Solar cell efficiency tables (version 18)
Authors: Green Martin A. , Emery Keith , King David L. , Igari Sanekazu , Warta Wilhelm
Published: January 2005

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries, since January 2001, are reviewed. Copyright © 2001 John Wiley & Sons, Ltd.
Proteomic analysis of salt stress‐responsive proteins in rice root
Authors: Yan Shunping , Tang Zhangcheng , Su Weiai , Sun Weining
Published: January 2005

Salt stress is one of the major abiotic stresses in agriculture worldwide. We report here a systematic proteomic approach to investigate the salt stress‐responsive proteins in rice (Oryza sativa L. cv. Nipponbare). Three‐week‐old seedlings were treated with 150 mM NaCl for 24, 48 and 72 h. Total proteins of roots were extracted and separated by two‐dimensional gel electrophoresis. More than 1100 protein spots were reproducibly detected, including 34 that were up‐regulated and 20 down‐regulated. Mass spectrometry analysis and database searching helped us to identify 12 spots representing 10 different proteins. Three spots were identified as the same protein, enolase. While four of them were previously confirmed as salt stress‐responsive proteins, six are novel ones, i.e. UDP‐glucose pyrophosphorylase, cytochrome c oxidase subunit 6b‐1, glutamine synthetase root isozyme, putative nascent polypeptide associated complex alpha chain, putative splicing factor‐like protein and putative actin‐binding protein. These proteins are involved in regulation of carbohydrate, nitrogen and energy metabolism, reactive oxygen species scavenging, mRNA and protein processing, and cytoskeleton stability. This study gives new insights into salt stress response in rice roots and demonstrates the power of the proteomic approach in plant biology studies.
Phosphoprotein profiling of erythropoietin receptor‐ dependent pathways using different proteomic strategies
Authors: Körbel Sandra , Büchse Tom , Prietzsch Holger , Sasse Tilo , Schümann Michael , Krause Eberhard , Brock Josef , Bittorf Thomas
Published: January 2005

Proteomic techniques provide new tools for the global analysis of protein profiles but also for the investigation of specific protein functions. The analysis of signaling cascades has traditionally been performed by the determination of enzymatic or transcription factor activities representing a certain pathway. Functional proteomics now allows more comprehensive approaches to study cellular responses induced during ligand/receptor interactions. In this study we evaluated proteomic strategies for the investigation of structure‐function relationships in the erythropoietin receptor signalling complex. After expression of epidermal growth factor/erythropoietin receptor mutant molecules in an identical cellular background we characterized their potential to induce cellular activities. Using this system we focused our efforts on post‐translational modifications of signalling proteins reflecting a substantial part of receptor‐dependent signaling events. Although tyrosine phosphorylated proteins were enriched by immunoprecipitation the analysis using the classical approach combining two‐dimensional gel electrophoresis and identification by matrix assisted laser desorption/ionization‐time of flight‐mass spectrometry revealed that low expressed signaling proteins cannot be detected by this technique. An alternative strategy using one‐dimensional gel separation of phosphoproteins and liquid chromatography‐tandem mass spectrometry, however, allowed us to identify multiple proteins involved in intracellular signalling representing already established pathways but also proteins which have not been linked to EPO‐induced signaling so far. This approach offers the potential to extend functional proteomic studies to complex signaling processes.
A comparison of immobilized pH gradient isoelectric focusing and strong‐cation‐exchange chromatography as a first dimension in shotgun proteomics
Authors: Essader Amal S. , Cargile Benjamin J. , Bundy Jonathan L. , Stephenson James L.
Published: January 2005

Recently, we have developed a high‐resolution two‐dimensional separation strategy for the analysis of complex peptide mixtures. This methodology employs isoelectric focusing of peptides on immobilized pH gradient (IPG) gels in the first dimension, followed by reversed‐phase chromatography in the second dimension, and subsequent tandem mass spectrometry analysis. The traditional approach to this mixture problem employs strong‐cation‐exchange (SCX) chromatography in the first dimension. Here, we present a direct comparison of these two first‐dimensional techniques using complex protein samples derived from the testis of Rattus norvegicus. It was found that the use of immobilized pH gradients (narrow range pH 3.5–4.5) for peptide separation in the first dimension yielded 13% more protein identifications than the optimized off‐line SCX approach (employing the entire pI range of the sample). In addition, the IPG technique allows for a much more efficient use on mass spectrometer analysis time. Separation of a tryptic digest derived from a rat testis sample on a narrow range pH gradient (over the 3.5–4.5 pH range) yielded 7626 and 2750 peptides and proteins, respectively. Peptide and protein identification was performed with high confidence using SEQUEST in combination with a data filtering program employing pI and statistical based functions to remove false‐positives from the data.
Density functional theory calculations of 17O and 13C NMR chemical shifts for aromatic acyl chlorides
Authors: Chao Ito , Chen Ko‐Wen , Hwang Tsong‐Song , Liu Kwang‐Ting
Published: January 2005

Density functional theory (DFT) at the B3LYP/6–31 + G(d,p)//B3LYP/6–31G(d) level was used to calculate 17O and 13C NMR chemical shifts of the carbonyl group of aromatic acyl chlorides 1a–n. The aryl groups included substituted phenyl, furyl, thienyl and naphthyl. The calculated 17O chemical shifts correlated well with the experimental values and with Hammett‐type σ+ constants. Therefore, in many cases it is possible to deduce σ+ constants of substituted aryl groups via gas‐phase calculation of 17O chemical shifts of the carbonyl groups. The σ+ values obtained in the gas‐phase calculation show the intrinsic property of substituents, so they provide a good reference set for systematic comparison to evaluate the effect of the environment. Furthermore, the concept of n–π* mixing can be used to understand the sensitivity of the O and Cl atoms and the insensitivity of the C atom towards substituent effects in aromatic acyl chlorides. Copyright © 2001 John Wiley & Sons, Ltd.
Substituent effects on benzyne electronic structures
Authors: Johnson William T. G. , Cramer Christopher J.
Published: January 2005

The effect of inductive strength and π‐conjugating tendency on the structure and energetics of singly substituted benzynes is studied for different substituents. For amino and cyano substituents, all possible isomers are examined. For silyl and ammonio substituents, meta isomers are examined. Copyright © 2001 John Wiley & Sons, Ltd.
Applications of non‐steady‐state kinetics in physical organic chemistry: guidelines for the resolution of the kinetics of complex reaction mechanisms
Authors: Parker Vernon D. , Zhao Yixing
Published: January 2005

The resolution of the kinetics of the reversible consecutive second‐order reaction mechanism

involving the formation of a kinetically significant intermediate, which does not reach steady state before late in the first half‐life, followed by an irreversible product‐forming reaction is discussed. It is shown that an apparent second‐order rate constant kapp and an extent of reaction–time profile are the only experimental data necessary for the evaluation of kf and kb (the forward and reverse rate constants) as well as kp (the microscopic rate constant for the product forming reaction). When the product‐forming step involves the cleavage of a CH bond, for which there is a deuterium kinetic isotope effect on kp, the resolution of the kinetics is enhanced. In this case, the experimental data include two apparent rate constants ($k_{\rm app}^{\rm H}$ and $k_{\rm app}^{\rm D}$) and two extent of reaction–time profiles, one for normal reactants and the other for isotopically substituted reactants. Under these circumstances, a unique highly resolved experimental to theoretical data fit is found that results in the evaluation of all four microscopic rate constants: $k_{\rm f},\,k_{\rm b},\,k_{\rm p}^{\rm H}$ and $k_{\rm p}^{\rm D}$. An alternative, when a kinetic isotope effect is not involved, is to fit the extent of reaction–time profiles for two or more concentrations of reactants concurrently. This procedure results in the resolution of the three microscopic rate constants for the reaction. Copyright © 2001 John Wiley & Sons, Ltd.
Deuterium conformational equilibrium isotope effects in 1,3,5‐cycloheptatriene‐7‐d
Authors: Freedberg Darón I. , Kopelevich Max , Anet Frank A. L.
Published: January 2005

We report a reinvestigation of the conformational equilibrium of 1,3,5‐cycloheptatriene‐7‐d (CHT‐7‐d) by solution 1H NMR at 500 MHz over a wide range of temperatures, and ab initio calculations up to the MP4 level. Lineshape analysis provided a barrier to ring inversion of approximately 6 kcal mol−1. Equilibrium constants were measured in CBrF3 and CClF2H by: integration when the ring‐inversion rate is low; lineshape analysis when the ­ring‐inversion rate is on the order of the chemical shift difference; and temperature‐dependent chemical shift differences between CHT and CHT‐7‐d when the ring‐inversion rate is fast. The three independent measure‐ments confirm an equilibrium biased toward an equatorial deuterium, with ΔG° = 52 ± 8 cal mol−1 (at −173 °C), ΔH° = 55 ± 8 cal mol−1 and ΔS° = 0.03 ± 0.05 cal mol−1 K−1 in CBrF3. Supporting ab initio calculations yield: ΔH° = 34 cal mol−1, ΔS° = 0.014 cal mol−1 K−1 (MP2/6‐31G*); ΔH° = 57 cal mol−1 and ΔS° = 0.03 cal mol−1 K−1 (RHF/6‐31G*); and a barrier to ring inversion in CHT of 4.26 kcal mol−1 (RHF/6‐31G*), 9.76 kcal mol−1 (MP2/6‐31G*), and 7.34 kcal mol−1 (MP4/6‐31G* single point). The differences in calculated barrier heights due to exclusion or inclusion of Møller–Plesset energies indicate that the ground state is stabilized relative to the transition state at ­the MP2 and MP4 levels. This implies that homoconjugation is important in CHT, a neutral molecule. Our experimental values differ from those originally deduced by Jensen and Smith (J. Am. Chem. Soc. 1964; 86: 956): ΔG° = 72 cal mol−1, ΔH° = 142 ± 30 cal mol−1 and ΔS° = 0.7 ± 0.3 cal mol−1 K−1. Copyright © 2001 John Wiley & Sons, Ltd.
Stability of 2‐naphthalenediazonium ion and its complexation with crown ethers and acyclic polyethers in solution
Authors: Kuokkanen Toivo , Palokangas Jarmo , Talvensaari Merja
Published: January 2005

The effects of solvent, temperature and pH (in aqueous solution) on the rate of decomposition of 2‐naphthalenediazonium tetrafluoroborate were studied by UV spectrometry. The host–guest complexation and the kinetics of thermal dediazoniation of this model naphthalenediazonium ion, in the presence of four crown ethers and three acyclic polyethers, were studied in 1,2‐dichloroethane (DCE) at 40 °C by UV spectrometry. Fast atom bombardment mass spectrometry (FAB‐MS) was used for the gas phase complexation and characterization.

The values of the activation enthalpy ΔH# for the thermal dediazoniation of the uncomplexed salt were observed to be high, and the corresponding values of activation entropy ΔS# were clearly positive. All hosts, except short 12‐crown‐4, formed 1:1 complexes under FAB conditions. The complexation equilibrium constant K and the values of the stabilizing ability of the complexation (k2/k1) in DCE were calculated using a kinetic method. In accordance with earlier studies of arene‐ and 1‐naphthalene diazonium ions, the thermodynamic and kinetic stabilities were observed to be greater for the inclusion complex—the largest for 21‐crown‐7 and its derivatives, formed with crown ethers containing at least six oxygen atoms—than for the non‐specific adduct formation formed with 15‐crown‐5. The values of the thermodynamic and kinetic macrocyclic effect were discussed. The results are consistent with a heterolytic SN1‐like mechanism involving the decomposition of the uncomplexed and complexed naphthalenediazonium ion into a highly reactive naphthyl cation, followed by fast product‐determining reactions with nucleophiles to give the products. Copyright © 2001 John Wiley & Sons, Ltd.
Protonation of alkylpyridines: polarizability and steric effects in the base and in the cation
Authors: Roithová Jana , Exner Otto
Published: January 2005

The energies of alkyl‐substituted pyridines in the 2‐, 3‐, 4‐ and 2,6‐positions, of their protonated forms and of reference derivatives of benzene were calculated at the RHF/6–31G(d,p) and B3LYP/6–31G(d,p) levels. The results were processed by isodesmic reactions, expressing the substituent effect separately for the base molecules, their protonated forms and for the gas‐phase basicity. The substituent effect is greatest in the protonated forms, and in the uncharged bases it is approximately three times smaller. In both cases, it is stabilizing: basicity is given by the difference. No actual steric effect was revealed, merely a stabilizing effect in the 2‐position, which can be explained in terms of polarization. This effect is almost equal in the protonated and unprotonated forms, so that it is not operative in the basicity. In water solution, all effects are attenuated and steric inhibition of solvation appears, particularly with 2,6‐di‐tert‐butylpyridine and 2,6‐diisopropylpyridine. Copyright © 2001 John Wiley & Sons, Ltd.
Product selectivities and third‐order rate laws for solvolyses of ethyl phenylphosphonochloridate in aqueous alcohols
Authors: Bentley T. William , Ebdon David N.
Published: January 2005

Rate constants and product selectivities (S) for solvolyses of ethyl phenylphosphonochloridate [PhP(O)OEtCl] in aqueous ethanol and methanol at 0 °C are reported; S = ([ester product]/[acid product]) ×­([water]/[alcohol solvent]). The results show trends very similar to those previously reported for solvolyses of diphenyl phosphorochloridate [(PhO)2P(O)Cl] and p,p′‐dichlorodiphenyl phosphorochloridate, much more hydrophobic substrates. Implications of these results are as follows: (i) as S increases about threefold from 99.8 to 90% alcohol–water and only about the same amount from 90 to 40% alcohol–water, the main cause of variations in S does not appear to be medium effects of the solvents; (ii) contrary to the general trend to increase, values of S may decrease slightly (ca 15%) in highly aqueous alcohol–water mixtures, even when (as in this case) there is no evidence for mechanistic changes; (iii) the deviations from expected third‐order rate product correlations previously reported for solvolyses of diphenyl phosphorochloridate and the p,p′‐dichloro derivative do not appear to be due solely to their high hydrophobicity. Copyright © 2001 John Wiley & Sons, Ltd.
Syntheses and UV–visible spectroscopic properties of new ‘fluorophilic’ fluorine‐ and perfluoroalkyl‐substituted solvatochromic pyridinium N‐phenolate betaine dyes
Authors: Reichardt Christian , Eschner Michael , Schäfer Gerhard
Published: January 2005

Syntheses and negative solvatochromism of three new ‘fluorophilic’ fluorine‐ and perfluoroalkyl‐substituted pyridinium N‐phenolate betaine dyes 3–5 are described in order to obtain new zwitterionic dyes which should be less basic and better soluble in perfluorinated solvents than the solvatochromic standard betaine dyes 1 and 2, used to establish an empirical scale of solvent polarity, called the E
T (30) or $E_{T}^{N}$ scale. The new betaine dyes 3–5 were designed to allow an extension of the existing E
T (30) scale to new solvents. Copyright © 2001 John Wiley & Sons, Ltd.
Angular group induced bond alternation (AGIBA). Part VI — Competition between the AGIBA and through resonance effects
Authors: Pindelska Edyta , Krygowski Tadeusz M. , Anulewicz‐Ostrowska Romana , Cyrański Michal K. , Nowacki Jacek
Published: January 2005

Analysis of the molecular geometry of three experimental model compounds, 2,3‐dimethyl‐p‐anisaldehyde, 2,5‐dimethyl‐p‐anisaldoxime and 2,3‐dimethyl‐p‐anisaldoxime, and eight compounds (p‐nitrosoaniline, p‐nitroanisole and two conformers each of p‐nitrosoanisole, p‐anisaldehyde and p‐anisaldimide) whose molecular geometry was obtained by optimization at the B3LYP/6–311G** level of theory, where both the AGIBA and through resonance effects were present, led to the conclusion that the competition between these effects does not reduce any of them significantly. Copyright © 2001 John Wiley & Sons, Ltd.
Revisit of the leaving group (LG)/halogen exchange in 1,2‐dimesityl‐2‐phenylvinyl–LG systems: a caveat about ‘mistaken identity’ by X‐ray diffraction
Authors: Salim Hatim , Chen Xin , Rappoport Zvi
Published: January 2005

The unusual report that Z‐1,2‐dimesityl‐2‐phenylethenol (Z
‐4‐OH) affords with POBr3 the crystallographically identified E‐1,2‐dimesityl‐2‐phenylvinyl bromide (E
‐4‐Br) was reinvestigated together with related reactions. Reaction of Z
‐4‐OH with tosyl chloride gave Z
‐4‐OTs, Z
‐4‐Cl with SOCl2 and Z
‐4‐Br with Me3SiCl/LiBr, PBr3 or PPh3/Br2. Reaction of Z
‐4‐OTs with Br− or I− in MeCN gave Z
‐4‐Br or Z
‐4‐I respectively. The reaction of Z
‐4‐OH with POBr3 was repeated under several conditions and gave Z
‐4‐Br, which was identified by X‐ray diffraction. The discrepancy with the previous experiment was ascribed to the formation of a minute percentage of E
‐4‐Br within the bulk of Z
‐4‐Br and to analysis of a crystal of E
‐4‐Br by X‐ray diffraction. The generalization that MesC(Ph) = C*‐Mes (* = · or +) species capture reagents (e.g. Br−, I− for 2 when * = +) from the face carrying the β‐mesityl ring is corroborated and extended. It is suggested that the reactions of Z
‐4‐OH with SOCl2, PBr3 or POBr3 proceed via initial formation of chlorosulfite or phosphorus‐containing ester leaving groups that solvolyze to 2 or its ion pair, which react with halide ions formed from the anionic leaving group to give Z
‐4‐X (X = Cl, Br). From the X‐ray data of MesC(Ph) = C(X)Mes, (X = Br, OAc, E and Z isomers; X = OTs, Cl, I, Z isomer; X = H, E isomer) the effect of X on bond lengths, angles and dihedral angles, as well as on the difference between the E/Z isomers (X = OAc, Br), is determined and discussed. Although steric crowding is important, its effect is significant mainly on the ArCC dihedral angles. 1H δ values for the nine systems show free rotation of all rings around the ArCC bonds on the NMR time scale. Higher field o‐Mes‐Me, m‐Mes‐H signals and lower field Ph‐H signals for the Z‐ than for the E‐isomers for X = OAc, Br were observed. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of the steric substituent effect by ΩS: reinvestigation of the reaction dependency of the steric substituent constant
Authors: Hirota Minoru , Sakakibara Kazuhisa , Yuzuri Tomoaki , Kuroda Shin‐ichi
Published: January 2005

Using the OMEGAS program, two sets [ΩS(0.5,0.5) and ΩS(0.9,0.5)] of steric substituents were calculated by assuming different sizes of effective radii for the reaction center atom. The former set reproduces the steric substituent effect on the nucleophilic reactions of carboxylic acid derivatives better; the latter set is far better for the reactions of amines and alcohol derivatives. Our results clearly show that the effective size of the reaction center atom is another important factor in characterizing the steric effect in addition to the bulkiness of the substituent. This can be rationalized by the fact that such a general steric constant cannot be used to evaluate all sorts of steric effects using a single set of substituent constants. Copyright © 2001 John Wiley & Sons, Ltd.
Tautomerism of neutral and monoprotonated histamine—a comparison of semi‐empirical and ab initio quantum mechanical predictions for ‘essential’ and ‘scorpio’ conformations
Authors: Raczyńska Ewa D. , Darowska Małgorzata , Rudka Tomasz , Makowski Mariusz
Published: January 2005

Relative energies were calculated at different semi‐empirical (CNDO, INDO, MINDO/3, MNDO, AM1, and PM3) and ab initio levels (RHF/STO‐3G//STO‐3G, RHF/STO‐4G//STO‐4G, RHF/3‐21G//3‐21G, RHF/6‐31G//6‐31G, RHF/6‐31G*//6‐31G, RHF/6‐31G*//6‐31G*, RHF/6‐31 ++ G**//6‐31G*, RHF/6‐311 ++ G**/6‐31G*, RHF/6‐31G**//6‐31G**, RHF/31 ++ G**//6‐31 ++ G**, MP2/6‐31G*//6‐31G* and MP2/6‐31G**//6‐31G**) for so‐called ‘essential’ (trans) and ‘scorpio’ (gauche) conformations of the neutral and monoprotonated histamine tautomers. For the monocationic forms, the polarizable continuous model was applied to geometries optimized at the RHF/6‐31G* level. The comparison shows that, generally, both types of calculation (semi‐empirical and ab initio) predict the same tautomeric preference for the conformations of histamine and its monoprotonated cation when not interacting with the environment, i.e. for conditions corresponding to the gas phase. For the monocation, the ring N‐aza protonated form (ImH+) is favoured in the gas phase for both conformations (trans and gauche); this is contrary to water solution, where the chain N‐amino (AmH+‐T1) predominates. This difference results mainly from the high polarizability of the imidazole ring in the gas phase which is strongly reduced in solution. Some ‘discrepancies’ are only observed for neutral histamine, for which the relative energy is close to zero. Good agreement of results predicted by various methods can result from the fact that in histamine the proton is transferred between atoms of the same element (nitrogen). Copyright © 2001 John Wiley & Sons, Ltd.
Reactions of carbonyl compounds in basic solutions. Part 36: The base‐catalysed reactions of 1,2‐dicarbonyl compounds
Authors: Bowden Keith , Fabian Walter M. F.
Published: January 2005

1,2‐Dicarbonyl compounds can undergo base‐catalysed reactions in three ways: rearrangement of the benzil–benzilic acid type, fission of the carbon–carbonyl carbon bond and fission of the carbonyl carbon–carbonyl carbon bond. The requirements for the observation of the variant reaction types are discussed both for open‐chain and for ring systems in terms of electronic and stereochemical factors. Copyright © 2001 John Wiley & Sons, Ltd.
Concerning the extent of nucleophilic participation in solvolyses of glucopyranosyl derivatives
Authors: Kevill Dennis N. , D'Souza Malcolm J.
Published: January 2005

The specific rates of solvolysis of 2‐deoxy‐α‐ and ‐β‐D‐glucopyranosyl‐4′‐bromoisoquinolinium ions (1 and 2) give excellent correlations in a Grunwald–Winstein equation approach for solvents with NT values more positive than −1.4; the sensitivity to changes in NT value is considerably reduced in less nucleophilic solvents. Copyright © 2001 John Wiley & Sons, Ltd.
Structural study of ethyl 3‐arylcarbamoyl‐2,3‐diazabicyclo[2.2.1]hept‐5‐ene‐2‐carboxylates: conformation and transmission of substituent effects across the diazabicycloheptene ring
Authors: Perjéssy A. , Meyer P. , Rudorf W.‐D. , Loos D. , Kolehmainen E. , Laihia K. , Nissinen M. , Koivisto J. , Kauppinen R.
Published: January 2005

Nine new ethyl 3‐arylcarbamoyl‐2,3‐diazabicyclo[2.2.1]hept‐5‐ene‐2‐carboxylates were prepared by a [4 + 2] cycloaddition and their FTIR, 1H, 13C and 15N NMR spectra were measured and assigned. Single crystals were grown for five compounds and their X‐ray data were obtained. The electronic structure and the conformations were calculated by the semi‐empirical AM1 method. Using correlations between the spectral, empirical and theoretical structural data, the transmission of substituent effects and the preferential conformation connected with the consecutive double nitrogen inversion and regarding the mutual orientation of NH and CO bonds were investigated. The results are compared with those for a previously reported series of analogous ethyl 2‐arylcarbamoyl‐4,5‐dimethyl‐1,2,3,6‐tetrahydropyridazine‐1‐carboxylates. Copyright © 2001 John Wiley & Sons, Ltd.
An enthalpic scale of hydrogen‐bond basicity, part 1: halogenoalkanes
Authors: Ouvrard Carole , Berthelot Michel , Laurence Christian
Published: January 2005

Hydrogen bond enthalpies ΔH° for the interaction of 4‐fluorophenol with 18 fluoro‐, chloro‐, bromo‐, and iodo‐alkanes in CCl4 solution have been determined through the temperature variation of hydrogen‐bond equilibrium constants. A statistical analysis of the ΔH°–ΔS° correlation shows that this extrathermodynamic relationship is valid for the family of halogenoalkanes. The enthalpic data are also used to test the correlation of ΔH° versus Δν(OH), the IR frequency shifts of the OH band of 4‐fluorophenol caused by the hydrogen bonding (the Badger–Bauer relationship). This relationship is family dependent, and, for fluoroalkanes and iodoalkanes, does not pass through the origin. These findings allow a safer use of the Badger–Bauer relationship to predict hydrogen‐bond enthalpies accurately. Copyright © 2001 John Wiley & Sons, Ltd.
Large structural effects in neutral and protonated species: a computational study
Authors: Abboud José‐Luis M. , Alkorta Ibon , Dávalos Juan Z.
Published: January 2005

The B3LYP/6‐31G(d) methodology was applied to the study of the diketone pentacyclo[5.4.0.02,6.03,10.05,9]undecane‐8,11‐dione (1), the hydrocarbon pentacyclo[5.4.0.02,6.03,10.05,9]undecane (2) and the ketone pentacyclo[5.4.0.02,6.03,10.05,9]undecane‐8‐one (3). Also examined were the oxygen‐protonated species 1H+ and 3H+. The diketone pentacyclo[5.4.0.02,6.03,10.05,9]undecane‐4,8‐dione (4) and the ketone pentacyclo[5.4.0.02,6.03,10.05,9]undecane‐4‐one (5) and their protonated forms were used for comparison purposes. This information was used to construct several isodesmic reactions, allowing the quantitative estimate of the influence of the carbonyl groups on the stability of the various species in the gas phase. These results were in excellent agreement with the experimental thermochemical and structural data available. Analyses by means of the natural bond orbital theory and simple electrostatic models were also performed. Copyright © 2001 John Wiley & Sons, Ltd.
Miscibility and properties of polyurethane/benzyl starch semi‐interpenetrating polymer networks
Authors: Cao Xiaodong , Zhang Lina
Published: January 2005

We successfully prepared a series of transparent materials with semi‐interpenetrating polymer networks (semi‐IPNs) from castor‐oil‐based polyurethane (PU) and benzyl starch (BS). The miscibility, morphology, and properties of the semi‐IPN films were investigated with attenuated total reflection/Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, scanning electron microscopy, wide‐angle X‐ray diffraction, electron spin resonance (ESR), ultraviolet–visible spectroscopy, and tensile testing. The results revealed that the semi‐IPN films had good or certain miscibility with BS concentrations of 5–70 wt % because of the strong intermolecular interactions between PU and BS. With an increase in the concentration of BS, the tensile strength and Young's modulus of the semi‐IPN materials increased. The ESR data confirmed that the segment volume of PU in the semi‐IPNs increased with the addition of BS; that is, the chain stiffness increased as a result of strong interactions between PU and BS macromolecules. It was concluded that starch derivatives containing benzyl groups in the side chains more easily penetrated the PU networks to form semi‐IPNs than those containing aliphatic groups, and this led to improved properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 603–615, 2005
Relaxations during the postcure of unsaturated polyester networks by ultrasonic wave propagation, dynamic mechanical analysis, and dielectric analysis
Authors: Lionetto Francesca , Maffezzoli Alfonso
Published: January 2005

Ultrasonic wave propagation, dynamic mechanical analysis, and dielectric analysis were used to monitor relaxation phenomena during the nonisothermal postcure of unsaturated polyester networks. The measurements covered 6 decades of frequency. As a result, the residual reactive groups, immobilized in the glassy state by vitrification during an isothermal cure step, gained molecular mobility, which promoted the formation of additional crosslinks. After the postcure, the reaction was complete, and the maximum achievable glass‐transition temperature was reached. Moreover, the frequency and temperature dependence of the two relaxations, one related to the glass‐transition temperature of the partially cured sample and the other to the glass transition of the fully cured sample, was evaluated. The Williams–Landel–Ferry equation was used to model the frequency dependence of the main α‐relaxation data obtained with the different techniques. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 596–602, 2005
Microgelivation versus macrogelivation: towards bridging the gap between laboratory and field frost weathering
Authors: Matsuoka Norikazu
Published: January 2005

The application of laboratory criteria for frost weathering to field problems needs caution, because a number of discrepancies lie between the laboratory and field conditions. This paper reviews thresholds for microgelivation of soft, intact rocks and macrogelivation of hard, jointed rocks, aiming at proposing better criteria in accordance with field conditions. The temperature at which ice segregation induces microgelivation varies significantly with lithology, ranging from about −1 °C in high porosity rocks to below −4 °C in low porosity rocks. Microgelivation can occur in initially unsaturated rocks when slow (seasonal) freezing drives prolonged water migration from surrounding rock or an external moisture source, while the occurrence requires a high degree of saturation (>80%) or a nearby moisture source when a rock undergoes rapid (diurnal) freezing. Rocks with a high internal surface area and low tensile strength favour microgelivation. These criteria are invalid for macrogelivation that tends to take place just below 0 °C in water‐filled joints. In addition, because the depth reached by cracking varies with the type of freeze‐thaw action, the analysis of thermal regimes should be based on data at the depth of actual cracking. Future targets for macrogelivation studies include the formation of new cracks in hard, intact rocks, as indicated by in situ shattering of clasts or bedrock typically observed in optimal moisture environments. Copyright © 2001 John Wiley & Sons, Ltd.
Stability of the tranquilizer drug propionylpromazine hydrochloride in formulated products
Authors: Primus Thomas M , Kimball Bruce A , Hurley Jerome , Johnston John J , Blom Sherm , Savarie Peter J
Published: January 2005

An analytical method to evaluate propionylpromazine hydrochloride (PPZHCl) in tranquilizer formulations was developed using high‐performance liquid chromatography (HPLC). During analysis of aged quality‐control samples, a previously unreported chromatographic response was observed at a shorter retention time than PPZHCl. Further investigation of formulations stored in trap tap devices at temperatures ranging from 5 to 40 °C during field trials at four different locations confirmed the degradation of the active ingredient. Further investigation using HPLC/tandem mass spectrometry revealed two to five degradates, with the major degradates being oxidation products of the active ingredient, PPZHCl. As PPZHCl formulations must be stable when stored at 5 to 40 °C for 6 to 12 months, reformulation with the anti‐oxidant ascorbic acid was utilized to achieve the required PPZHCl stability. Copyright © 2005 Society of Chemical Industry
Local and systemic effects of oxylipins on powdery mildew infection in barley
Authors: Cowley Tracy , Walters Dale
Published: January 2005

Treatment of the first leaves of barley seedlings with the oxylipin colneleic acid, or the two trihydroxy oxylipins 9,12,13‐trihydroxy‐11(E)‐octadecenoic acid and 9,12,13‐trihydroxy‐10(E)‐octadecenoic acid, reduced infection of that leaf by the powdery mildew fungus Blumeria graminis Speer f sp hordei Marchal. When applied to first leaves, etheroleic acid and colneleic acid, as well as the trihydroxy oxylipin 9,12,13‐trihydroxy‐10(E),15(Z)‐octadecadienoic acid, also reduced mildew infection in second leaves. In all cases where local and systemic effects against mildew were observed, activity of the defence‐related enzyme phenylalanine ammonia lyase (PAL) was increased, but only following challenge inoculation with powdery mildew. Peroxidase activity was not affected by oxylipin treatment or mildew inoculation. Whether the effects observed were due to the oxylipins or to breakdown products is not known, since no information is available on the stability of these particular oxylipins on leaf surfaces. Nevertheless, these data represent the first report of systemic effects against pathogen infection following pre‐treatment with oxylipins. Copyright © 2005 Society of Chemical Industry
Translocation and translaminar bioavailability of two neonicotinoid insecticides after foliar application to cabbage and cotton
Authors: Buchholz Anke , Nauen Ralf
Published: January 2005

A laboratory study was undertaken to investigate the leaf systemic properties and the translaminar aphicidal activity of two commercialised neonicotinoid (chloronicotinyl) insecticides. For that purpose [14C]imidacloprid was subjected to uptake and translocation studies in cabbage and cotton after foliar application. Foliar penetration and short‐term translocation patterns of imidacloprid were similar in both plant species. Nevertheless imidacloprid penetrated twice as much into cabbage leaves as it did into cotton leaves. It showed a comparable translaminar behaviour and was entirely translocated acropetally, indicating its well‐known xylem mobility. The translaminar and acropetal movement of imidacloprid and acetamiprid were quantified by simple laboratory bioassays using the green peach aphid, Myzus persicae (Sulzer), and the cotton aphid, Aphis gossypii (Glover), as typical homopteran pests for cabbage and cotton, respectively. A single dose (7.5 µg AI per leaf) applied to the upper leaf surface of cabbage and cotton was tested against aphids feeding on the lower leaf surface both close to and distant from the site of application 1, 5 and 12 days after treatment. The translaminar residual activity of imidacloprid on cabbage leaves was superior to that of acetamiprid, whereas its translaminar efficacy against A gossypii on cotton was inferior to that of acetamiprid. However, oral ingestion bioassays using an artificial double membrane feeding system revealed no significant differences in intrinsic activity between the two neonicotinoids tested.

© 2001 Society of Chemical Industry
Spatial variability in herbicide degradation in the subsurface environment of a groundwater protection zone
Authors: Wood Martin , Issa Salah , Albuquerque Miriam , Johnson Andrew C
Published: January 2005

The aim of this study was to investigate the spatial variability in degradation and mineralization of atrazine and isoproturon in subsurface samples taken from sandy loam soils overlying gravel terraces which form part of a groundwater protection zone. Percussion drilling was used to obtain samples from 11 boreholes (maximum depth 3 m). Unlabelled atrazine or isoproturon, and ring‐14C‐labelled atrazine or isoproturon were added to samples, incubated at 25 °C for up to 16 weeks, and analyzed for the residual herbicide or [14C]carbon dioxide. All samples showed the potential to degrade these herbicides, although the percentage degradation decreased by a factor of 2–3 from the surface soil to a depth of 3 m. This was associated with a decrease in organic matter content, but there was no change in the potential to mineralize acetate, indicating that specific changes in the catabolic ability of the microbial population occurred with depth. The capacity of samples to mineralize atrazine and isoproturon to carbon dioxide decreased markedly with depth, with no mineralization potential observed at a depth of 80 cm.

© 2001 Society of Chemical Industry
The effect of foliar application of phosphonate formulations on the susceptibility of potato tubers to late blight
Authors: Cooke Louise R , Little George
Published: January 2005

Foliar sprays of potato plants with phosphonic acid (partially neutralised with potassium hydroxide to pH 6.4) substantially reduced infection of the tubers by Phytophthora infestans, the cause of late blight, in glasshouse and field experiments over a 4‐year period. Healthy tubers of blight‐susceptible cultivars removed from treated plants and artificially inoculated by spraying with sporangial/zoospore suspensions of P infestans did not develop disease symptoms, demonstrating that the phosphonate applications had directly reduced the susceptibility of tubers to infection, probably as a result of translocation into tuber tissue. In contrast, foliar application of fosetyl‐aluminium did not significantly reduce tuber blight development following inoculation. Five to six sprays of partially neutralised phosphonic acid (2 kg ha−1) applied at 10–14 day intervals resulted in the least tuber infection, but such a treatment regime may not be economic. In trials where the effect of timing and rate of application of 2–4 kg phosphonic acid ha−1 was examined, a single treatment of 4 kg ha−1 applied mid‐ or late‐season proved the most effective. A spray programme in which one or two applications of phosphonic acid are combined with use of a non‐systemic or systemic fungicide to enhance foliar protection offers the possibility of controlling both foliage and tuber blight and could have a major impact in reducing overwinter survival of P infestans in tubers.

© 2001 Society of Chemical Industry
New, quick tests for herbicide resistance in black‐grass (Alopecurus myosuroides Huds) based on increased glutathione S‐transferase activity and abundance
Authors: Reade John P H , Cobb Andrew H
Published: January 2005

Black‐grass (Alopecurus myosuroides Huds) is a major grass weed in winter cereals in Europe. It reduces yields and can act as a secondary host for a range of diseases. Herbicide resistance in this species was first detected in the UK in the early 1980s, and has now been reported in thirty counties. To successfully manage herbicide resistance it is vital that suspect populations are tested so that appropriate action can be taken. Ideally, a test will be quick, cheap and easy to use. Furthermore, it should provide an unequivocal result before post‐emergence herbicides are to be applied, allowing alternative strategies to be adopted where necessary. This paper reports the development of new tests for herbicide resistance based on our observation that the resistant black‐grass biotype Peldon contains approximately double the activity of the enzyme glutathione S‐transferase (GST) compared with susceptible biotypes. Data are presented on the production of a monoclonal antiserum to a novel 30 kDa GST polypeptide purified from the biotype Peldon. An ELISA using this antiserum is described and the utility of this assay to detect resistant black‐grass biotypes in plants grown under glass and in the field is presented. In addition, a microtitre assay for GST activity is described, which allows the rapid assessment of GST activities of plants. Both abundance and activity of GSTs are discussed as markers for herbicide resistance in black‐grass.

© 2001 Society of Chemical Industry
Antimicrobial and pesticidal activity of partially purified flavonoids of Annona squamosa
Authors: Kotkar Hemlata M , Mendki Prashant S , Sadan Sangeetha V G S , Jha Shipra R , Upasani Shripad M , Maheshwari Vijay L
Published: January 2005

Foliar extracts of Annona squamosa (Family: Annonaceae) were screened for antimicrobial and insecticidal activity against the common microbial infestants of pulses and the stored grain pest pulse beetle, Callosobruchus chinensis (Coleoptera: Bruchidae). Flavonoids isolated from aqueous extracts of A squamosa showed antimicrobial activity against all the common microbial contaminants of pulses and 80% insecticidal activity against C chinensis at a concentration of 0.07 mg ml−1. Various physico‐chemical tests, chromatographic and spectroscopic studies with partially purified aqueous extract indicated the presence of flavonol type flavonoids. This may provide a useful beginning for the development of botanical pesticides for post‐harvest safeguard of pulses.

© 2001 Society of Chemical Industry