bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular modeling and inhibitory activity of cowpea cystatin against bean bruchid pests
Authors: Aguiar Juliana M. , Franco Octávio L. , Rigden Daniel J. , Bloch Carlos , Monteiro Ana C.S. , Flores Victor M.Q. , Jacinto Tânia , Xavier‐Filho José , Oliveira Antonia E.A. , Grossi‐de‐Sá Maria F. , Fernandes Kátia V.S. 
Published: February 2006

AbstractPlant cystatins show great potential as tools to genetically engineer resistance of crop plants against pests. Two important potential targets are the bean weevilsAcanthoscelides obtectusandZabrotes subfasciatus, which display major activities of digestive cysteine proteinases in midguts. In this study a cowpea cystatin, a cysteine proteinase inhibitor found in cowpea (Vigna unguiculata) seeds, was expressed inEscherichia coliand purified with a Ni‐NTA agarose column. It strongly inhibited papain and proteinases from midguts of bothA. obtectusandZ. subfasciatusbruchids, as seen by in vitro assays. When the protein was incorporated into artificial seeds at concentrations as low as 0.025%, and seeds were consumed by the bruchids larva, dramatic reductions in larval weight, and increases in insect mortality were observed. Molecular modeling studies of cowpea cystatin in complex with papain revealed that five N‐terminal residues responsible for a large proportion of the hydrophobic interactions involved in the stabilization of the enzyme–inhibitor complex are absent in the partial N‐terminal amino acid sequencing of soybean cystatin. We suggest that this structural difference could be the reason for the much higher effectiveness of cowpea cystatin when compared to that previously tested phytocystatin. The application of this knowledge in plant protein mutation programs aiming at enhancement of plant defenses to pests is discussed. Proteins 2006. © 2006 Wiley‐Liss, Inc.
The fragment transformation method to detect the protein structural motifs
Authors: Lu Chih‐Hao , Lin Yeong‐Shin , Chen Yu‐Ching , Yu Chin‐Sheng , Chang Shi‐Yu , Hwang Jenn‐Kang 
Published: February 2006

AbstractTo identify functional structural motifs from protein structures of unknown function becomes increasingly important in recent years due to the progress of the structural genomics initiatives. Although certain structural patterns such as the Asp‐His‐Ser catalytic triad are easy to detect because of their conserved residues and stringently constrained geometry, it is usually more challenging to detect a general structural motifs like, for example, the ββα‐metal binding motif, which has a much more variable conformation and sequence. At present, the identification of these motifs usually relies on manual procedures based on different structure and sequence analysis tools. In this study, we develop a structural alignment algorithm combining both structural and sequence information to identify the local structure motifs. We applied our method to the following examples: the ββα‐metal binding motif and the treble clef motif. The ββα‐metal binding motif plays an important role in nonspecific DNA interactions and cleavage in host defense and apoptosis. The treble clef motif is a zinc‐binding motif adaptable to diverse functions such as the binding of nucleic acid and hydrolysis of phosphodiester bonds. Our results are encouraging, indicating that we can effectively identify these structural motifs in an automatic fashion. Our method may provide a useful means for automatic functional annotation through detecting structural motifs associated with particular functions. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Terminal ion pairs stabilize the second β‐hairpin of the B1 domain of protein G
Authors: Huyghues‐Despointes Beatrice M. P. , Qu Xiaotoa , Tsai Jerry , Scholtz J. Martin 
Published: February 2006

AbstractThe effects of terminal ion pairs on the stability of a β‐hairpin peptide corresponding to the C‐terminal residues of the B1 domain of protein G were determined using thermal unfolding as monitored by nuclear magnetic resonance and circular dichroism spectroscopy. Molecular dynamics (MD) simulations were also performed to examine the effect of ion pairs on the structures. Eight peptides were studied including the wild type (G41) and the N‐terminal modified sequences that had the first residue deleted (E42), replaced with a Lys (K41), or extended by an additional Gly (G40). Acetylated variants were made to examine the effect of removing the positive N‐terminal charge on β‐hairpin stability. The rank in stability determined experimentally is K41 > E42 ≈ G41 ≈ G40 > Ac‐K41 > Ac‐E42 ≈ Ac‐G41 > Ac‐G40. The Tm of the K41 peptide is 12 °C higher than G41, while the Tm values for the acetylated peptides are less than their unacetylated forms by more than 15 °C. NOE cross‐peaks between side‐chain methylene groups at the N‐ and C‐termini and larger CαH shifts compared to random values are seen for K41. The addition of 20% methanol increases the stability in K41 and G41. The MD studies complement these results by showing that the charged N‐terminus is important to stability. The type of ion pair observed varies with peptide, and when formed the simulations show that the ion pair can prevent fraying of the β‐strands through electrostatic and hydrophobic contacts. Therefore, introducing favorable electrostatic interactions at the N‐ and C‐termini can substantially enhance β‐hairpin stability and help define the structure. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Investigating the in situ degradation of atrazine in groundwater
Authors: Pearson Robert , Godley Andrew , Cartmell Elise 
Published: February 2006

AbstractThis study focused on whether or not atrazine could be degraded by indigenous groundwater bacteria as part of an in situ remediation approach. Groundwater was taken from an unconfined middle upper chalk site where concentrations of atrazine and nitrate were typically in the ranges 0.02–0.2 µg litre−1 and 11.6–25.1 mg NO3‐N litre−1 respectively. Sacrificial batch studies were performed using this groundwater spiked with atrazine at a concentration of 10 µg litre−1 in conjunction with a minimal mineral salts liquid (Glu‐MMSL) medium which contained glucose as the sole carbon source. Treatments comprised either the Glu‐MMSL groundwater cultured bacteria or Pseudomonas sp. strain ADP. Results from sacrificial batches indicated the occurrence of bacterial growth and denitrification as monitored by optical density (absorbance at 600 nm) and NO3‐N content. Analysis of atrazine content by solid phase extraction coupled with high‐performance liquid chromatography showed no degradation of atrazine over a period of 103 days in either treatment. These results indicated that no acclimatised bacterial community featuring positive degraders to the herbicide atrazine had become established within this chalk aquifer in response to the trace levels encountered. Copyright © 2006 Society of Chemical Industry
The effect of insecticide application sequences on the control and insecticide resistance status of the peach‐potato aphid, Myzus persicae (Hemiptera:Aphididae), on field crops of potato
Authors: Parker William E , Howard Julia J , Foster Stephen P , Denholm Ian 
Published: February 2006

AbstractExperiments were done on commercial potato crops in the UK to investigate the effect of different insecticide sequences on the control and insecticide resistance status of Myzus persicae (Sulzer). The work was done to provide field validation of similar laboratory studies done in ‘field simulators’. To ensure adequate aphid populations and to influence the initial resistance status of the aphid population, cultured M. persicae from a clone of known resistance status (esterase R1, kdr heterozygote, non‐MACE (modified acetylcholinesterase)) were inoculated into both experiments. Two‐spray programmes starting with λ‐cyhalothrin (a pyrethroid insecticide) gave poor control in comparison with programmes starting with pirimicarb (a carbamate insecticide) or pirimicarb‐containing mixtures. This concurred closely with the results obtained from single applications in field simulator studies. Treatment sequences containing pymetrozine (a pyridine azomethine insecticide) were also effective, though slower‐acting. This again concurs with field simulator studies. The proportions of aphids carrying different resistance mechanisms were largely unaffected by treatment in these experiments. The implications of these results for field control strategies are discussed. Copyright © 2006 Society of Chemical Industry
Improved efficacy of ethyl formate against stored grain insects by combination with carbon dioxide in a ‘dynamic’ application
Authors: Haritos Victoria S , Damcevski Katherine A , Dojchinov Greg 
Published: February 2006

AbstractEthyl formate is being evaluated as a fumigant for stored grain as it is a potential alternative to the ozone‐depleting fumigant methyl bromide and to phosphine, which is under pressure owing to the development of strong resistance in stored grain insects. However, use of ethyl formate faces significant challenges, such as poor penetration through grain, significant losses to grain sorption, high concentrations of fumigant required to control insects, and flammability risks, which have limited its further development. In this study it was found that the combination of carbon dioxide (5–20%) with ethyl formate significantly enhanced efficacy of the fumigant against external living stages of the rice weevil, Sitophilus oryzae (L.), the lesser grain borer, Rhyzopertha dominica F., and the flour beetle, Tribolium castaneum (Herbst). Dynamic application of ethyl formate and carbon dioxide mixture (100 mg litre−1 ethyl formate, 20% CO2) pumped through a model silo containing wheat (50 kg) for one gas exchange was also investigated. A flow rate of 6 litres min−1 gave a relatively even distribution of fumigant throughout the grain column and similar mortality levels among cultures of S. oryzae and T. castaneum placed at three positions, the top, middle and bottom of the column. Mortality of 99.8% of mixed stage cultures of T. castaneum and 95.1% of S. oryzae was achieved in 3 h exposures to 111 and 185 mg ethyl formate h litre−1 respectively applied by the dynamic method. It is concluded that the combination of carbon dioxide with ethyl formate and dynamic application enhances distribution and efficacy of the fumigant against stored grain insects. Copyright © 2006 Society of Chemical Industry
Use of oils combined with low doses of insecticide for the control of Myzus persicae and PVY epidemics
Authors: Martín‐López Begoña , Varela Ianire , Marnotes Silvia , Cabaleiro Cristina 
Published: February 2006

AbstractExperiments were carried out in the laboratory to assess the insecticidal effect on Myzus persicae Sulzer of different oils applied alone or combined with imidacloprid or pirimicarb. The oils tested were a horticultural mineral oil, a refined rapeseed oil, a refined soya oil and a raw fish oil. When the oils were sprayed alone on pepper plants infested with M. persicae, mineral oil caused the highest mortality of aphids (over 80%). Applied before aphid infestation of pepper leaves and in mixture with low doses of imidacloprid (at one‐fifth of the dose recommended by the manufacturer) and pirimicarb (at one‐tenth of the dose recommended by the manufacturer), the oils did not significantly increase the toxicity of the insecticides alone. However, sprayed on aphid‐infested pepper plants, the mortality rates achieved by imidacloprid/mineral oil and imidacloprid/rapeseed oil mixtures were significantly higher than those achieved by imidacloprid alone at 16 and 24 h. In a field experiment the effect on the incidence of the potato virus (PVY) of the oils in combination with imidacloprid was determined. Mineral oil, rapeseed oil and soya oil were sprayed eight times onto seed potato plants treated with imidacloprid before sowing. Mineral oil reduced PVY‐infected plants by 60% and rapeseed oil by 40% compared with plots treated with imidacloprid. The oils applied as 10 ml litre−1 emulsions in water did not cause symptoms of phytotoxicity on the potato plants, and yield was not reduced. Copyright © 2006 Society of Chemical Industry
Studies on the structure and conduction mechanism of (Acrd)[Au(mnt)2]2.7 and (Phenz)[Au(mnt)2]3 molecular single crystals
Authors: Hafiz Hafiz Rashad 
Published: February 2006

AbstractTwo quasi‐one‐dimensional acridinium (Acrd) and phenazinium (Phenz) molecular conductors with a single anion of maleonitriledithiolato aurate (Au(mnt)2) were obtained by electrochemical crystallization. The Acrd single crystal was found to have a non‐stoichiometric composition donor (D):acceptor (A) = 1:2.7, whereas the Phenz single crystal was found to have a stoichiometric composition D:A = 1:3. Crystal structure analysis revealed that the former has a monoclinic lattice with a = 9.26, b = 7.63, c = 27.76, β = 104.8, Z = 2, and the latter has a monoclinic lattice with a = 17.06, b = 14.46, c = 28.30, β = 108.3, Z = 6. The Acrd radicals were assumed to form alternate stacking with the anion sublattice due to the appearance of satellite reflections indicating a sinusoidal modulation structure. The Phenz single crystal was verified as adopting cation stacks with disorder in the anion sublattice. The results were supported by FTIR spectroscopy and cyclovoltammetry measurements. The room temperature dc conductivity of the Phenz crystal was found to be about two orders of magnitude higher than that of the Acrd crystal. A quasi‐one‐dimensional conduction mechanism was proposed for the Phenz crystal but a conventional nearest‐neighbour hopping mechanism was shown to best describe conduction in the Acrd single crystal exhibiting a well‐defined metal‐to‐insulator transition. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resonant cavity enhanced optical microsensor for molecular interactions based on porous silicon
Authors: De Stefano Luca , Rea Ilaria , Rendina Ivo , Rotiroti Lucia , Rossi Mosè , D'Auria Sabato 
Published: February 2006

AbstractThe molecular binding between the glutamine binding‐protein (GlnBP) from Escherichia coli and L‐glutamine (Gln) is detected by means of an optical biosensor based on porous silicon technology. The binding event is optically transduced in the wavelength shift of the porous silicon optical microcavity (PSMC) reflectivity spectrum. The hydrophobic interaction links the GlnBP, which acts as a molecular probe for Gln, to the hydrogenated porous silicon surface area. We can thus avoid any preliminary surface functionalization process. The protein infiltrated PSMC results stable to oxidation at least for few cycles of wet measurements. The penetration of the proteins into the pores of the porous silicon matrix has been optimized: a strong base post‐etch process increases the pore size and removes any nanostructure on top and inside the porous silicon multilayer while does not degrade the optical response and the quality of the microcavity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of rapid thermal processing on oxide precipitation in conventional and nitrogen‐doped Czochralski silicon
Authors: Ma Xiangyang , Fu Liming , Tian Daxi , Cui Can , Yang Deren 
Published: February 2006

AbstractIn this paper, the effects of vacancies introduced by rapid thermal processing (RTP) on nucleation and growth of oxide precipitates in Czochralski (Cz) silicon are elucidated. Moreover, the nitrogen and vacancy enhancement roles in oxide precipitation are differentiated through designing specific annealing schemes. Furthermore, it is pointed out that the RTP‐based internal gettering process for a nitrogen‐doped Cz silicon wafer should be different from that for a conventional Cz silicon wafer in order to strengthen the intrinsic gettering capability. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ge‐dots/Si multilayered structures fabricated by Ni‐induced lateral crystallization
Authors: Shi Y. , Yan B. , Pu L. , Zhang K. J. , Han P. , Zhang R. , Zheng Y. D. 
Published: February 2006

AbstractWe report on the fabrication of high‐quality Ge‐dots/Si multilayered structure films by metal‐induced lateral crystallization (MILC). Ge dots are self‐assembled grown on amorphous Si layer using low‐pressure chemical vapor deposition, and then low‐temperature crystallization is carried out by Ni‐based MILC processing. The micro Raman spectroscopy, optical microscopy and electron microscopy observations reveal that the crystallized Si film has large leaf‐like grains elongated along the MILC direction with (110) preference. Moreover, the strain shift of Ge dots reflects the formation of high quality interface between the crystallized Si and Ge dot. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Involvement of iron–phosphorus complexes in iron gettering for n‐type silicon
Authors: Mchedlidze T. , Kittler M. 
Published: February 2006

AbstractMechanisms for phosphorus (P) diffusion gettering (PDG) for iron are supplemented by possible formation of iron–phosphorus complexes in heavy P‐doped region. Existence of such complexes was recently reported based on the results of electron‐spin resonance investigations. DLTS measurements suggest a high probability for the formation of iron–phosphorus complexes in n‐type silicon in the presence of vacancies and/or vacancy–phosphorus pairs. On the other hand, recent theoretical calculations predict formation of negatively charged vacancy–phosphorus pairs in the heavily P‐doped region of silicon during PDG. These facts indicate on possibility to explain the high efficiency of the PDG process for iron by assuming formation of iron–phosphorus complexes in the heavy P‐doped region of silicon. Possible advantages of application of hydrogen or nitrogen assisted PDG are considered. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A contribution to oxide precipitate nucleation in nitrogen doped silicon
Authors: Kissinger G. , Lambert U. , Weber M. , Bittersberger F. , Müller T. , Richter H. , von Ammon W. 
Published: February 2006

AbstractBased on Fourier transform infrared (FTIR) spectroscopy and bulk micro‐defect investigations, in relation to earlier results of other groups, we suggest the following model for oxide precipitate nucleation in N‐doped silicon. Around 600 °C a nucleation maximum exists where oxide precipitates are formed via oxygen attachment to both NOO and NNO complexes. These complexes are formed by the reaction of NN with interstitial oxygen. Vacancy supersaturation enhances this type of precipitate nucleation. A second nucleation maximum exists around 900 °C. This is assumed to be due to a vacancy assisted oxynitride SiOx Ny based nucleation process. The higher density of the oxynitride phase compared to silicon oxide and a higher residual vacancy concentration would explain the observed shift of the maximum nucleation rate to higher temperatures around 900 °C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuous‐wave and tunable laser operation of Tm:LuVO4 near 1.9 µm under Ti:sapphire and diode laser pumping
Authors: Mateos X. , Liu J. , Zhang H. , Wang J. , Jiang M. , Griebner U. , Petrov V. 
Published: February 2006

AbstractWe demonstrate for the first time to our knowledge laser oscillation of Tm:LuVO4 at room temperature with both Ti:sapphire and diode laser pumping, and tunable operation from 1839 to 1952 nm. Spectroscopic studies indicate higher gain cross section for the σ‐polarization as observed in the laser experiments. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simultaneous determination of tanshinone IIA and its three hydroxylated metabolites by liquid chromatography/tandem mass spectrometry
Authors: Li Peng , Wang Guang‐Ji , Li Jing , Hao Hai‐Ping , Zheng Chao‐Nan 
Published: February 2006

AbstractA rapid and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of tanshinone IIA and its three hydroxylated metabolites, tanshinone IIB, hydroxytanshinone IIA and przewaquinone A, in a rat liver microsome was developed and fully validated. A single step of liquid‐liquid extraction with ethyl acetate was utilized in this method. Chromatographic separation of the sample matrix from the analytes and the internal standard diazepam was performed using a Shim‐pack VP‐ODS analytical column. Detection was performed on a triple quadrupole tandem mass spectrometer equipped with an electrospray ionization source and operated in selected reaction monitoring (SRM) mode. The method was linear in the concentration range of 1–500 ng/mL for all analytes. The intra‐ and inter‐day precisions (RSD %) were within 15% and deviations of the assay accuracies were within 15.0% for all analytes. The analytes proved to be stable during sample storage, preparation and analyses. This validated method was successfully applied to the enzyme kinetic study of tanshinone IIA in liver microsome. The elimination of tanshinone IIA and formation of tanshinone IIB and hydroxytanshinone IIA in the liver microsome all exhibited a sigmoidal kinetics profile. The formation of przewaquinone A shows a typical hyperbolic profile. In addition, this method has now been applied in the analysis of other bio‐samples including plasma, urine, bile and feces. Copyright © 2006 John Wiley & Sons, Ltd.
Screening for amphetamine and amphetamine‐type drugs in doping analysis by liquid chromatography/mass spectrometry
Authors: Deventer K. , Van Eenoo P. , Delbeke F. T. 
Published: February 2006

AbstractA selective and sensitive method for the qualitative screening of urine samples for 27 amphetamine and amphetamine‐type drugs in the field of doping analysis is described. The method consists of a liquid‐liquid extraction with diethyl ether at pH 14 and analysis of the extracts with a LCQ‐Deca® mass spectrometer equipped with an atmospheric pressure chemical ionisation interface, operated in positive ionisation mode. The total run time was 15 min. All compounds were analysed in MS2 or MS3. The detection limit for all compounds was lower than 25 ng/mL except for chlorphentermine (detection limit: 250 ng/mL). Copyright © 2006 John Wiley & Sons, Ltd.
A comparison of the electron ionization and electrospray behaviour of some N,N′‐disubstituted hexahydropyrimidines
Authors: Orelli Liliana R. , García María B. , Perillo Isabel A. , Tonidandel Loris , Traldi Pietro 
Published: February 2006

AbstractThe behaviour of some N,N′‐disubstituted hexahydropyrimidines, a class of naturally occurring compounds of biological and biomedical interest, has been studied in both electron ionization (EI) and electrospray ionization (ESI) modes coupled with collisional experiments (ESI‐MSn). In both techniques, the [M–H]+ ions are highly abundant, even if their formation is generated by two different mechanisms, i.e. H. loss from the M+. species in the case of EI and hydride (H−) abstraction from the molecules in the case of ESI. Furthermore, due to the low, step‐by‐step internal energy deposition typical of collisional experiments performed in an ion trap mass spectrometer, different fragment ions were observed in EI and ESI‐MSn collisions. In both cases, the ions can be related to the original structure and allow us to identify the positions in which the different substituents are present. Copyright © 2006 John Wiley & Sons, Ltd.