bluuebunny/crossref_metadata_2025_split huggingface dataset:
Profiling the chlorogenic acids of Rudbeckia hirta, Helianthus tuberosus, Carlina acaulis and Symphyotrichum novae‐angliae leaves by LC‐MSn
Authors: Jaiswal Rakesh , Deshpande Sagar , Kuhnert Nikolai 
Published: April 2011

ABSTRACTIntroductionChlorogenic acids (CGAs) are a family of esters formed between quinic acid and certain cinnamic acids, most commonly caffeic, p‐coumaric and ferulic acid. They show a variety of biological activities like antioxidant, anti‐inflammatory, anti‐HIV, anti‐HBV and inhibition of mutagenesis and carcinogenesis, and are considered to be beneficial to human health. We have selected well‐established plants of Asteraceae family and these are used in folk medicines as antivirals.ObjectiveInvestigating the CGA profile of anti‐viral herbal remedies, we aim at identifying selected chlorogenic acids commonly encountered in these plants in order to identify suitable candidates for anti‐viral screening. It should be noted that neuroaminidase inhibitors, recently introduced into the clinical practice as Tamiflu or Relenza, bear a remarkable structural similarity to CGAs, suggesting potentially a similar mode of action.MethodologyMethanolic extracts were used for LC‐MS analysis. The LC equipment with DAD detector was interfaced with a high‐resolution MicroTOF mass spectrometer for molecular formula assignment and an ion trap mass spectrometer for assignment of CGA regiochemistry based on characteristic fragmentation patterns. For the identification of cis cinnamoylquinic acids, extracts were treated with UV‐irradiation.ResultsA series of CGAs were identified by their tandem mass spectra and retention times. We also found that diacyl CGAs containing cis isomer of cinnamic acids have the same tandem MS spectra as those containing the trans isomer.ConclusionIn this study, all the CGAs present in the leaves of Rudbeckia hirta, Helianthus tuberosus, Carlina acaulis and Symphyotrichum novae‐angliae were identified qualitatively to their regioisomeric level without any purification or isolation, and assignment was based on their LC‐MSn behaviour and the change in the intensity after the UV‐irradiation. A series of CGAs common to these anti‐viral herbal remedies was identified, which will in the future be selected for further detailed biological screening. Copyright © 2011 John Wiley & Sons, Ltd.
Size‐dependent optical properties of transparent, spin‐coated polystyrene/ZnO nanocomposite films
Authors: Jeeju Pullarkat P , Sajimol Augustine M , Sreevalsa Vallath G , Varma Sreekanth J , Jayalekshmi S 
Published: April 2011

AbstractZinc oxide (ZnO) nanoparticles are synthesized using a simple chemical method at room temperature. A variation in molar concentration of the precursor, potassium hydroxide, from 0.25 to 0.01 mol L−1 is accompanied by a decrease in the average size of the nanoparticles. These nanoparticles are used for the preparation of polystyrene/ZnO nanocomposite films using the spin‐coating technique. These films are found to be highly transparent throughout the visible region and absorb UV light in the region from 395 to190 nm, almost covering the near and middle UV ranges (400 to 200 nm). This observation highlights the possible prospects of these films in UV shielding applications. The wavelength corresponding to the onset of UV absorption is found to be blue shifted with a decrease in size of the ZnO particles in the composite films due to confinement effects. The photoluminescence spectra of the composite films also change as a function of particle size. The emissions at longer wavelength due to defects and impurity‐related states in ZnO are almost quenched as a result of surface modification by the polymer matrix. The observed band‐gap enlargement with a decrease in size of the ZnO particles in the composite films is significant for band‐gap engineering of nanoparticles for various applications. Copyright © 2011 Society of Chemical Industry
Multi‐Scale Investigation of a Colloid Micro‐Propulsion System
Authors: Morris Trevor , Forget Martin , Malardier‐Jugroot Cecile , Jugroot Manish 
Published: April 2011

AbstractElectric propulsion is highly efficient for both deep‐space and near‐earth applications and it is an excellent candidate for small satellites. A colloidal electrostatic thruster for small spacecrafts is investigated in the present paper. A multi‐disciplinary approach (encompassing several scales of modelling: fluid, particle trajectory and molecular modelling) is adopted in order to gain an increased understanding of complex underlying physical processes. The governing factors are accessed in order to obtain the onset and maintenance of a focused beam of droplets or ions. The trajectories and characteristics of the droplets and ions are investigated and multi‐electrode configurations are parameterized by simulations. The flow from the capillary needle, just before the droplets are formed, is also investigated by fluid methods. The molecular modelling provides interesting information on the different modes of emission from the perspective of the stability of the ions. The multi‐scale results obtained are fully discussed and the valuable insights provided by the simulations are also currently fully helping in the design of a laboratory model of an electric micro‐propulsion system for small spacecrafts. magnified image
Binding to the open conformation of HIV‐1 protease
Authors: Lexa Katrina W. , Carlson Heather A. 
Published: April 2011

AbstractA recent crystal structure of HIV‐1 protease (HIVp) was the first to experimentally observe a ligand targeting an open‐flap conformation. Researchers studying a symmetric pyrrolidine inhibitor found that two ligands cocrystallized with the protease, forcing an unusual configuration and unique crystallographic contacts. One molecule is centered in the traditional binding site (α pose) and the other binds between the flaps (β pose). The ligands stack against each other in a region termed the “eye” site. Ligands bound to the eye site should prevent flap closure, but it is unclear if the pyrrolidine inhibitors or the crystal packing are causing the open state. Molecular dynamics simulations were used to examine the solution‐state behavior of three possible binding modes: the ternary complex of HIVp+αβ and the binary complexes, HIVp+α and HIVp+β. We show that HIVp+α is the most stable of the three states. During conformational sampling, α takes an asymmetric binding pose, with one naphthyl ring occupying the eye site and the other reoriented down to occupy positions seen with traditional inhibitors. This finding supports previous studies that reveal a requirement for asymmetric binding at the eye site. In fact, if the α pose is modified to splay both naphthyl rings across the binding site like traditional inhibitors, one ring consistently flips to occupy the eye site. Our simulations reveal that interactions to the eye site encourage a conformationally restrained state, and understanding those contacts may aid the design of ligands to specifically target alternate conformations of the protease. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Increased toxicity of Bacillus thuringiensis Cry3Aa against Crioceris quatuordecimpunctata, Phaedon brassicae and Colaphellus bowringi by a Tenebrio molitor cadherin fragment
Authors: Gao Yulin , Jurat‐Fuentes Juan Luis , Oppert Brenda , Fabrick Jeffrey A , Liu Chenxi , Gao Jianhua , Lei Zhongren 
Published: April 2011

AbstractBACKGROUND: Biopesticides containing Cry insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are effective against many lepidopteran pests, but there is a lack of Bt‐based pesticides for efficient control of important coleopteran pests. Based on the reported increase in Bt toxin oligomerization by a polypeptide from the Cry3Aa receptor cadherin in Tenebrio molitor (Coleoptera: Tenebrionidae), it was hypothesized that this cadherin peptide, rTmCad1p, would enhance Cry3Aa toxicity towards coleopteran larvae. To test this hypothesis, the relative toxicity of Cry3Aa, with or without rTmCad1p, against damaging chrysomelid vegetable pests of China was evaluated.RESULTS: Cry3Aa toxicity was evaluated in the spotted asparagus beetle (Crioceris quatuordecimpunctata), cabbage leaf beetle (Colaphellus bowringi) and daikon leaf beetle (Phaedon brassicae). To assess the effect of rTmCad1p on Cry3Aa toxicity, neonate larvae were fed Cry3Aa toxin alone or in combination with increasing amounts of rTmCad1p. The data demonstrated that Cry3Aa toxicity was significantly increased in all three vegetable pests, resulting in as much as a 15.3‐fold increase in larval mortality.CONCLUSION: The application of rTmCad1p to enhance Cry3Aa insecticidal activity has potential for use in increasing range and activity levels against coleopteran pests displaying low susceptibility to Bt‐based biopesticides. Copyright © 2011 Society of Chemical Industry
Effects of disease control by fungicides on greenhouse gas emissions by UK arable crop production
Authors: Hughes David J , West Jonathan S , Atkins Simon D , Gladders Peter , Jeger Michael J , Fitt Bruce DL 
Published: April 2011

AbstractBACKGROUND: The UK government has published plans to reduce UK agriculture's greenhouse gas (GHG) emissions. At the same time, the goal of global food security requires an increase in arable crop yields. Foliar disease control measures such as fungicides have an important role in meeting both objectives.RESULTS: It is estimated that UK winter barley production is associated with GHG emissions of 2770 kg CO2 eq. ha−1 of crop and 355 kg CO2 eq. t−1 of grain. Foliar disease control by fungicides is associated with decreases in GHG emissions of 42–60 kg CO2 eq. t−1 in UK winter barley and 29–39 kg CO2 eq. t−1 in UK spring barley. The sensitivity of these results to the impact of disease control on yield and to variant GHG emissions assumptions is presented. Fungicide treatment of the major UK arable crops is estimated to have directly decreased UK GHG emissions by over 1.5 Mt CO2 eq. in 2009.CONCLUSION: Crop disease control measures such as fungicide treatment reduce the GHG emissions associated with producing a tonne of grain. As national demand for food increases, greater yields as a result of disease control also decrease the need to convert land from non‐arable to arable use, which further mitigates GHG emissions. Copyright © 2011 Society of Chemical Industry
Genetic study of Mediterranean and South American populations of tomato leafminer Tuta absoluta (Povolny, 1994) (Lepidoptera: Gelechiidae) using ribosomal and mitochondrial markers
Authors: Cifuentes Dina , Chynoweth Robert , Bielza Pablo 
Published: April 2011

AbstractBACKGROUND: Before its introduction into Europe at the end of 2006, Tuta absoluta (Povolny, 1994) was confined solely to South America. Currently, this invasive pest is well established in various European and Mediterranean countries, causing important economic losses to tomato (Lycopersicon esculentum Mill.) crops. In order to study the genetic variability of this pest, 23 Mediterranean and ten native South American populations were analysed with nuclear ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA) markers.RESULTS: The internal transcribed spacers 1 (ITS1) and 2 (ITS2) of rDNA and a fragment in the mtDNA gene encoding cytochrome oxidase I (COI) were PCR amplified and sequenced in T. absoluta. Sequence analyses consistently revealed neither intrapopulation nor interpopulation variation in either genomic region.CONCLUSIONS: High genetic homogeneity was detected in T. absoluta populations from the Mediterranean Basin and South America, based on mtCOI and ITS rDNA sequence analysis. A single genetic type was identified in this pest. Copyright © 2011 Society of Chemical Industry
Structure–activity relationship study of antioxidative peptides by QSAR modeling: the amino acid next to C‐terminus affects the activity
Authors: Li Yao‐Wang , Li Bo , He Jiguo , Qian Ping 
Published: April 2011

AbstractScreening, isolation and in vitro assays have been used for characterization of antioxidative peptides derived from food proteins, and incompatible deductions of structural characteristics derived from the isolated peptides have been brought forward. However, there is still little information concerning the structure‐activity relationship of antioxidative peptides. QSAR modeling was performed, respectively, on synthetic tripeptides and tetrapeptides related to LLPHH. According to cumulative squared multiple correlation coefficients (R2), cumulative cross‐validation coefficients (Q2) and relative standard deviation for calibration set (RSDc), two credible models for tripeptide and tetrapeptide databases, respectively, have been built with partial least squares (PLS) regression (R2 for models of tripeptide and tetrapeptide are 0.744 and 0.943, Q2 are 0.631 and 0.414, and RSDc are 0.323 and 0.111, respectively). Meanwhile, according to the cumulative multiple correlation coefficient for the predictive set ($R_{\rm {ext}}^{2}$) and the relative standard deviation for the predictive set (RSDp), the predictive ability of the model for tripeptides also is excellent ($R_{\rm {ext}}^{2}$ and RSDp are 0.719 and 0.450, respectively). Hydrogen bond property and hydrophilicity of the amino acid residue next to the C‐terminus, and the hydrophobicity as well as electronic propertyof the N‐terminus are more significant; meanwhile, the electronic property of the C‐terminus is beneficial for antioxidant activity. The structural characteristics we found are very useful in understanding and predicting the peptide structures responsible for activity and development of functional foods with peptides as active compounds, or antioxidative peptides as alternatives to other antioxidants. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis of the orthogonally protected amino alcohol Phaol and analogs
Authors: Nelissen Jo , Nuyts Koen , Dehaen Wim , De Borggraeve Wim M. 
Published: April 2011

AbstractThe development of a multigram synthesis of the orthogonally protected amino acid‐derived Phaol [2‐{[(2S)‐2‐amino‐3‐phenylpropyl]amino}ethanol] is described. The goal of this work is to synthesize an orthogonally protected Phaol in a multigram scale up to 10 g (Cbz‐Phaol), so it can be used in solution‐based peptide synthesis of peptaibols. Two synthetic schemes were proposed and examined. Between the reduction‐coupling and the coupling‐reduction scheme, the latter gave the best results. A two‐step synthesis affords easily purifiable products. Several analogs were synthesized using this methodology. All the molecules were orthogonally protected, so that they can be used in peptide synthesis. Deprotection posed no problems. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis, preferred conformation, protease stability, and membrane activity of heptaibin, a medium‐length peptaibiotic
Authors: De Zotti Marta , Biondi Barbara , Peggion Cristina , Park Yoonkyung , Hahm Kyung‐Soo , Formaggio Fernando , Toniolo Claudio 
Published: April 2011

AbstractThe medium‐length peptaibiotics are characterized by a primary structure of 14–16 amino acid residues. Despite the interesting antibiotic and antifungal properties exhibited by these membrane‐active peptides, their exact mechanism of action is still unknown. Here, we present our results on heptaibin, a 14‐amino acid peptaibiotic found to exhibit antimicrobial activity against Staphylococcus aureus. We carried out the very challenging synthesis of heptaibin on solid phase and a detailed conformational analysis in solution. The peptaibiotic is folded in a mixed 310‐/α‐helix conformation which exhibits a remarkable amphiphilic character. We also find that it is highly stable toward degradation by proteolytic enzymes and nonhemolytic. Finally, fluorescence leakage experiments using small unilamellar vesicles of three different compositions revealed that heptaibin, although uncharged, is a selective compound for permeabilization of model membranes mimicking the overall negatively charged surface of Gram‐positive bacteria. This latter finding is in agreement with the originally published antimicrobial activity data. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Peptide synthesis ‘in water’ by a solution‐phase method using water‐dispersible nanoparticle Boc‐amino acid
Authors: Hojo Keiko , Ichikawa Hideki , Onishi Mare , Fukumori Yoshinobu , Kawasaki Koichi 
Published: April 2011

AbstractRegulatory pressure has compelled the chemical manufacturing industry to reduce the use of organic solvents in synthetic chemistry, and there is currently a strong focus on replacing these solvents with water. Here, we describe an efficient in‐water solution‐phase peptide synthesis method using Boc‐amino acids. It is based on a coupling reaction utilizing suspended water‐dispersible nanoparticle reactants. Using this method, peptides were obtained in good yield and with high purity. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Applications of CASSCF
Authors: Larsson Sven 
Published: April 2011

AbstractMulticonfigurational wave functions are necessary in a number of applications such as breaking of bonds and curve crossing problems. One of the most important multiconfigurational methods is CASSCF. Three applications are discussed here: cis‐trans isomerization, as a reasonably simple curve crossing problem. Curve crossing connected to electron‐transfer contains the additional problem that the electronic interaction |Δ| may tend to zero. The electron pair transfer problem includes multiconfigurational wave functions and requires a very accurate calculation of the interaction between two configurations, the charged and spin‐coupled configurations. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem 111:3424–3430, 2011
PREDICTING RIVER DIATOM REMOVAL AFTER SHEAR STRESS INDUCED BY ICE MELTING
Authors: Bona F. , La Morgia V. , Falasco E. 
Published: April 2011

ABSTRACTThe augmentation of fine particles and water velocity may have important effects on river biota, which have not been fully clarified. The aim of this study is to relate the removal of diatoms to changes in environmental variables during high‐stage flow in alpine streams.To achieve this goal, we adopted a path analysis approach. We hypothesized a causal model relating diatom presence to environmental predictors, and we tested it against data collected in two alpine rivers in NW Italy (Aosta Valley): Dora di Veny, directly fed by glaciers of the M. Bianco massif, and Savara, fed by springs. Total suspended solids (TSS) and velocity values were much higher in Dora di Veny, with a maximum velocity of 2.9 m s−1 and a maximum TSS of 2180 mg L−1. Absence of epilithic diatoms was recorded only three times in Savara, whereas it occurred in roughly half the samples in Dora di Veny. Diatom recolonization after natural removal generally occurred in early autumn, with a dominance of tightly attached forms. According to our path model, the explanatory variables causally related to the presence/absence of diatoms were water velocity, TSS and river feeding. The model estimated both direct and indirect effect weights of water velocity, thus discriminating the respective roles of shear stress (velocity) and abrasion of the substrates/increased turbidity (TSS, partly mediated by velocity).Our model allowed estimation of TSS and velocity threshold values and therefore inferences on the impact of physical alterations induced by natural or human causes. From a practical point of view, this may represent an applied outcome in the environmental impact assessment of engineering works and other human activities that could increase the TSS in rivers. Copyright © 2011 John Wiley & Sons, Ltd.
INFLUENCE OF THE MORPHOLOGICAL AND HYDRAULIC CHARACTERISTICS OF MOUNTAIN STREAMS ON FISH HABITAT SUITABILITY CURVES
Authors: Macura V. , Škrinár A. , Kaluz K. , Jalčovíková M. , Škrovinová M. 
Published: April 2011

ABSTRACTMicrohabitat preferences of adult brown trout (Salmo trutta m. fario) were monitored for the purpose of determining design parameters for river restoration. The habitat preferences were evaluated during the summer period of minimum flows. Since 1995, field measurements have been performed in 52 reaches in 43 mountain and piedmont streams. The relationship between hydraulic characteristics and the values of maximum habitat suitability derived from velocity and depth habitat suitability curves (HSCs) was statistically determined. Trout in natural stream reaches showed a strong degree of dependence on depths, but in regulated streams, they were dependent on velocities.The representative habitat suitability curves for four depth intervals were extrapolated. From these outputs, the optimum depths of a microhabitat for river restoration measures and/or assessment of the influence of water withdrawals can be derived. The influence of geological regions on the shape of HSCs has not been proved; therefore, it is conceivable that after verification, the generalized HSCs may also be valid in other mountain and piedmont regions. Copyright © 2011 John Wiley & Sons, Ltd.
The “tortuous evolution” of international management research: Critical issues on the way to maturity
Authors: Michailova Snejina 
Published: April 2011

AbstractThe field of international management (IM) is undergoing a “tortuous evolution” on its way to maturity. This article identifies five critical issues that arise along this evolution: (1) identity struggles; (2) no strong and clear impact on IM practice; (3) emphasizing instrumentalities; (4) not enough true and continuous interdisciplinarity; and (5) articulation of ideas and findings as if they emerge in a vacuum. The article seeks possible explanations of the underlying causes of these critical issues. It is argued that the five critical issues contribute to explaining why IM research has not yet fulfilled its potential. Suggestions are offered on how improvements can be made. ©2011 Wiley Periodicals, Inc.
Coping with work‐family conflicts in the global career context
Authors: Mäkelä Liisa , Suutari Vesa 
Published: April 2011

AbstractIn order to increase our understanding of the work‐family conflicts experienced by global careerists and their families and the related coping strategies they adopt to address them, managers with long‐term global careers were interviewed. The results indicate that the challenging nature of their jobs means global careerists face not only time‐based and strain‐based work‐family conflicts but also mobility‐based conflicts, a category added in order to fully capture the work‐family conflicts faced. Managers were found mainly to use active problem‐solving strategies alongside family‐level coping strategies, though, in addition, emotional coping, avoidance, and reappraisal strategies were in evidence. ©2011 Wiley Periodicals, Inc.
Procedures for preventing juvenile violence in Switzerland: The Zurich model
Authors: Endrass Jérôme , Rossegger Astrid , Urbaniok Frank , Laubacher Arja , Pierce Christine Schnyder , Moskvitin Konstantin 
Published: April 2011

AbstractThe Swiss legal system places strong emphasis on risk assessment and treatment of potentially violent offenders. Especially after the 2001 Zug massacre, there is close cooperation between the judicial and mental health systems to prevent violence through early detection and intervention. A case study of a risk management program for a dangerous seventeen‐year‐old delinquent youth illustrates this approach.