bluuebunny/crossref_metadata_2025 huggingface dataset:
Matrix solid‐phase dispersion with sand in chromatographic analysis of essential oils in herbs
Authors: Dawidowicz Andrzej L. , Wianowska Dorota , Rado Ewelina
Published: August 2010

Introduction – Matrix solid‐phase dispersion (MSPD) is a very simple, cheap and relatively quick sample preparation procedure which involves simultaneous disruption and extraction of various solid and semi‐solid samples due to the direct mechanical blending of the sample with a SPE sorbent, mainly C18. Little is known about MSPD application as a sample preparation method for the analysis of essential oil components in herbs.

Objective – To evaluate if C18 sorbent, commonly used in MSPD process, can be substituted with sand in the procedure of essential oil analysis.

Methodology – Essential oil extracts were obtained from mint, sage, chamomile, marjoram, savory and oregano using MSPD with C18 sorbent or sand, pressurised liquid extraction and steam distillation. Their qualitative and quantitative compositions ware established by GC‐MS and GC‐FID.

Results – The results prove that C18 sorbent can be substituted with sand in the procedure of essential oil analysis in herbs. The recoveries of essential oil components estimated using MSPD/sand are almost equal to those using pressurised liquid extraction.

Conclusion – The results presented in the paper reveal that MSPD with sand is suitable for the isolation of essential oil components from herbs. Its extraction efficiency is equivalent to pressurised liquid extraction, recognised as one of the most efficient extraction methods. The cost of MSPD procedure for essential oil analysis can be significantly diminished by substituting C18 with sand. Copyright © 2010 John Wiley & Sons, Ltd.
Systematic characterisation of secondary metabolites from Ixeris sonchifolia by the combined use of HPLC‐TOFMS and HPLC‐ITMS
Authors: Shi Peiying , Zhang Yufeng , Qu Haibin , Fan Xiaohui
Published: August 2010

Introduction – Ixeris sonchifolia (Bunge) Hance, a folk medicine, has been widely used in China for its anti‐inflammatory and haemostatic effects. However, the miscellaneous component composition of this herbal medicine is not well known.

Objective – To develop a fast and comprehensive analytical method for the characterisation of various components from I. Sonchifolia, as a tool for the quality control of the herb and its related preparations.

Methodology – Ixeris sonchifolia samples were extracted with 60% aqueous methanol, purified by solid‐phase extraction and then analysed by the combinatorial use of HPLC‐TOFMS and HPLC‐ITMS.

Results – A total of six sesquiterpene lactones, six phenolic acids and seven flavonoids were identified or tentatively characterised. Five of them were reported for the first time in I. sonchifolia and, in particular, two amino acid‐sesquiterpene lactone conjugates, 11,13‐dihydro‐13‐prolyl‐ixerin Z and 11,13‐dihydro‐13‐prolyl‐ixerin Z1, that were first found in this plant source.

Conclusion – A global profile of I. sonchifolia constituents was described, which could be useful for the quality control of this herb and its related preparations. The employed combination of HPLC‐TOFMS and HPLC‐ITMS could also be a promising tool for the analysis of other herbal medicines containing sesquiterpene lactones, phenolic acids or flavonoids. Copyright © 2010 John Wiley & Sons, Ltd.
A comparison of alternative sample preparation procedures for the analysis of swainsonine using LC‐MS/MS
Authors: Gardner Dale R. , Cook Daniel
Published: August 2010

Introduction – Swainsonine, a polyhydroxy indolizidine alkaloid and known glycosidase inhibitor, is found in a number of different plants that cause a lysosomal storage disease known as locoism in the western USA. Most recently swainsonine has been analysed by LC‐MS/MS after sample extraction and preparation from ion‐exchange resins.

Objective – To compare previously published sample preparation procedures with several new alternative procedures to provide methods using either commercially available solid‐phase extraction equipment or procedures which significantly reduce sample preparation time.

Methodology – A previously reported and validated sample preparation method using ion‐exchange resin was compared with methods using a commercially available solid‐phase extraction cartridge, a solvent partitioning procedure or a single solvent extraction procedure using one of two solvents. Twenty different plant samples of varying swainsonine concentrations were prepared in triplicate and analysed by LC‐MS/MS. The measured concentration of swainsonine was then statistically compared between methods.

Results – There were no statistically significant differences found between four of the five different sample preparation methods tested.

Conclusion – A commercially available SPE cartridge can be used to replace the previously used ion‐exchange resin for swainsonine analysis. For very rapid analyses the SPE procedure can be eliminated and a simple, single solvent extraction step used for sample preparation. Published in 2010 by John Wiley & Sons, Ltd.
Ethnic differences in participation in prenatal screening for Down syndrome: A register‐based study
Authors: Fransen Mirjam P. , Schoonen Marleen H. M. H. J. D. , Mackenbach Johan P. , Steegers Eric A. P. , de Koning Harry J. , Laudy Jacqueline A. M. , Galjaard Robert‐Jan , Looman Caspar W. N. , Essink‐Bot Marie‐Louise , Wildschut Hajo I. J.
Published: August 2010

Objective

To assess ethnic differences in participation in prenatal screening for Down syndrome in the Netherlands.

Methods

Participation in prenatal screening was assessed for the period 1 January 2009 to 1 July 2009 in a defined postal code area in the southwest of the Netherlands. Data on ethnic origin, socio‐economic background and age of participants in prenatal screening were obtained from the Medical Diagnostic Centre and the Department of Clinical Genetics. Population data were obtained from Statistics Netherlands. Logistic regression models were used to assess ethnic differences in participation, adjusted for socio‐economic and age differences.

Results

The overall participation in prenatal screening was 3865 out of 15 093 (26%). Participation was 28% among Dutch women, 15% among those from Turkish ethnic origin, 8% among those from North‐African origin, 15% among those from Aruban/Antillean origin and 26% among women from Surinamese origin.

Conclusions

Compared to Dutch women, those from Turkish, North‐African, Aruban/Antillean and other non‐Western ethnic origin were less likely to participate in screening. It was unexpected that women from Surinamese origin equally participated. It should be further investigated to what extent participation and non‐participation in these various ethnic groups was based on informed decision‐making. Copyright © 2010 John Wiley & Sons, Ltd.
Aiming at multidisciplinary consensus: what should be detected in prenatal diagnosis?
Authors: Boormans Elisabeth M. A. , Birnie E. , Knegt Alida C. , Schuring‐Blom G. Heleen , Bonsel Gouke J. , van Lith Jan M. M.
Published: August 2010

Objective

To determine expert consensus on which chromosomal abnormalities should and should not be detected in prenatal diagnosis, and for which abnormalities disagreement remains after structured discussion.

Methods

An expert panel of 24 prenatal experts (8 clinical cytogeneticists, 8 clinical geneticists and 8 obstetricians) rated 15 chromosomal abnormalities sampled from a nationwide study on rapid aneuploidy detection (RAD). In two individual anonymous rating rounds and one group meeting, the participants rated PRO or AGAINST detection and stated their main argument. The 15 chromosomal abnormalities were described in detail by a stylized vignette containing an obstetrical history, the indication for prenatal diagnosis and the range of possible outcomes of the chromosomal abnormality. Consensus was defined to be present if at least 80% of the experts agreed.

Results

Consensus was reached in 12 out of 15 cases. In ten cases, there was agreement PRO detection and in two cases experts agreed AGAINST detection. At the end of the third round, dissensus remained on three abnormalities.

Conclusion

Experts largely agreed on detecting chromosomal abnormalities with severe consequences and AGAINST detection in case of irrelevant clinical consequences. For chromosomal abnormalities with mild or uncertain outcomes, dissensus remained. None of the currently available tests corresponds to these demands. Copyright © 2010 John Wiley & Sons, Ltd.
Fundamental losses in solar cells
Authors: Hirst Louise C. , Ekins‐Daukes Nicholas J.
Published: August 2010

This paper considers intrinsic loss processes that lead to fundamental limits in solar cell efficiency. Five intrinsic loss processes are quantified, accounting for all incident solar radiation. An analytical approach is taken to highlight physical mechanisms, obscured in previous numerical studies. It is found that the free energy available per carrier is limited by a Carnot factor resulting from the conversion of thermal energy into entropy free work, a Boltzmann factor arising from the mismatch between absorption and emission angles and also carrier thermalisation. It is shown that in a degenerate band absorber, a free energy advantage is achieved over a discrete energy level absorber due to entropy transfer during carrier cooling. The non‐absorption of photons with energy below the bandgap and photon emission from the device are shown to be current limiting processes. All losses are evaluated using the same approach providing a complete mathematical and graphical description of intrinsic mechanisms leading to limiting efficiency. Intrinsic losses in concentrator cells and spectrum splitting devices are considered and it is shown that dominant intrinsic losses are theoretically avoidable with novel device designs. Copyright © 2010 John Wiley & Sons, Ltd.
High performance wire‐array silicon solar cells
Authors: Gunawan O. , Wang K. , Fallahazad B. , Zhang Y. , Tutuc E. , Guha S.
Published: August 2010

Nano/micro‐wire silicon solar cells, consisting of wire‐arrays of radial p–n junction structures, are expected to offer performance enhancement at lower costs, using smaller volumes of low carrier lifetime, cheaper silicon. Using inexpensive microsphere‐lithography‐based fabrication that is scalable to large areas, we have demonstrated wire‐array solar cells that outperform the control cell. Key to the design of these cells is the impact of various parameters, such as wire diameter and junction depth, that influences the competing effects of light trapping ability of the wire‐array, quantum efficiency, and series resistance of the resulting device. Using capacitance measurements we can identify two possible types of junction structure in a wire‐array solar cell: radial and planar. We show that the former is the prerequisite for performance‐enhancing wire‐array solar cells. Copyright © 2010 John Wiley & Sons, Ltd.
Variation of the chemical reactivity of Thermus thermophilus HB8 ribosomal proteins as a function of pH
Authors: Running William E. , Reilly James P.
Published: September 2010

Ribosomes occupy a central position in cellular metabolism, converting stored genetic information into active cellular machinery. Ribosomal proteins modulate both the intrinsic function of the ribosome and its interaction with other cellular complexes, such as chaperonins or the signal recognition particle. Chemical modification of proteins combined with mass spectrometric detection of the extent and position of covalent modifications is a rapid, sensitive method for the study of protein structure and flexibility. By altering the pH of the solution, we have induced non‐denaturing changes in the structure of bacterial ribosomal proteins and detected these conformational changes by covalent labeling. Changes in ribosomal protein modification across a pH range from 6.6 to 8.3 are unique to each protein, and correlate with their structural environment in the ribosome. Lysine residues whose extent of modification increases as a function of increasing pH are on the surface of proteins, but in close proximity either to glutamate and aspartate residues, or to rRNA backbone phosphates. Increasing pH disrupts tertiary and quaternary interactions mediated by hydrogen bonding or ionic interactions, and regions of protein structure whose conformations are sensitive to these changes are of potential importance in modulating the flexibility of the ribosome or its interaction with other cellular complexes.
CH hydrogen bonding: 3. Hammett correlations for phenylacetonitriles and tetrafluorobenzenes with HMPA
Authors: Lorand John P.
Published: August 2010

Understanding the hydrogen bond, or H‐bond, arguably the strongest known intermolecular attractive force, is of great importance. Models of H‐bonding hold that both electrostatic and covalent components are at work. H‐bonding of CH bonds, and thus presumably other AH bonds, is greatly facilitated by polar substituents. We have found that equilibrium constants, K, for CH H‐bonding in series of phenylacetonitriles and tetrafluorobenzenes with HMPA are closely correlated by the Hammett equation. That is, K values vary as substituents of different polarities are introduced at positions remote from the donor CH bond. This result is consistent with a significant electrostatic component in these examples of H‐bonding. It may, however, also be explained by interaction with the σ* orbital of the CH bond, which is involved in the covalent component of the H‐bond. Theoretical models need to be applied to this and other cases. Copyright © 2010 John Wiley & Sons, Ltd.
Structure development in multistage stretching of PTFE films
Authors: Choi Kyung‐Ju , Spruiell Joseph E.
Published: September 2010

The structure of expanded poly(tetrafluoroethylene) (ePTFE) films that were produced by uniaxial or biaxial stretching of a calendared sheet were studied by wide angle X‐ray diffraction (WAXD), small angle X‐ray scattering, differential scanning calorimetry (DSC), and scanning electron microscopy. The molecular orientation of the stretched films was analyzed by WAXD flat films and pole figures. Biaxial orientation factors were computed to interpret the level of orientation quantitatively. DSC scans showed that oriented samples exhibited two melting peaks, one at the commonly observed temperature in the range 340–345 °C and one around 380 °C. The possible causes of this high‐temperature melting peak and its relation to previously described processes is discussed. The microporous nature of the ePTFE films is also briefly discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Surface modification and characterization of SEBS films obtained by in situ and ex situ oxidization with potassium permanganate
Authors: Han Xia , Zhou Yuan , Hu Jun , Liu Honglai
Published: September 2010

The surface morphologies and compositions of the asymmetric films of polystyrene‐b‐poly(ethylene‐co‐butylene)‐b‐polystyrene (SEBS) prepared by in situ and ex situ oxidization with the KMnO4 aqueous solution and KMnO4/H2SO4 mixed solution were investigated by using scanning electron microscope, atomic force microscope (AFM), X‐ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATR‐FTIR). The effect of the oxidization reagents on morphological changes and the influence of in situ and ex situ preparation methods on surface compositions were discussed. Different from the in situ oxidation by degrading the copolymers to form a gradient film, the ex situ oxidation preferentially degraded the uppermost layer of the film. Although both the KMnO4 oxidation and the KMnO4/H2SO4 oxidation gave hierarchical structures, distinctive differences were found that large ridges and smaller granules were fabricated in the former film and the latter produced large and deep ravines and fine sponge‐like morphologies. Additionally, the oxygen concentration and the oxo‐species implanted by these oxidation treatments were characterized and evaluated to provide a quantitative comparison. Oxygen, as well as manganese was found to be implanted in the surface layer of the oxidized film, forming predominantly OC and OCO groups, as well as a small fraction of OH and MnO compounds. Changes in contact angle of water on these films and total surface oxygen content are related but not directly. The hystereses of water contact angle at a value of 119 ± 3° due primarily to surface roughness and at a value of 63 ± 3° due primarily to chemical heterogeneity are led by different oxidation degrees and oxidation methods. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Facilitating reproductive choices: the impact of health services on the experiences of young women with breast cancer
Authors: Lee Rebecca J. , Wakefield Ann , Foy Sharon , Howell Sacha J. , Wardley Andrew M. , Armstrong Anne C.
Published: September 2010

Objective: Chemotherapy and hormone treatments carry significant implications on the fertility of young women with breast cancer. Increasingly, nulliparous women experience fertility dilemmas due to rising survival rates and pregnancy delay. This qualitative study investigated women's responses to being told that treatments affected their fertility and how their interactions with health services impacted on their experiences.

Methods: Twenty‐four women under 40 years participated in three focus groups using a flexible interview structure. Data were analysed using content analysis and participants subsequently member checked the themes generated.

Results: The priority for most women was survival, although women without children were more willing to take risks. Many women felt that pregnancy after breast cancer and methods of egg harvesting carried a significant risk to survival and fears appeared to be increased by conflicting advice from health professionals. Overall, the women felt the cancer, its treatment options and the health service itself had each robbed them of choice. Hence, with hindsight, many said they would have welcomed an open and honest discussion with a fertility expert to maximise their options.

Conclusions: Young women with breast cancer face complex decisions regarding their fertility and treatment options. Survival remains the priority for the majority of women. Although there is a paucity of evidence concerning many fertility issues, it is essential that available options and any potential risks are discussed in a coherent, objective fashion. Early referral to specialist fertility services that provide clear, cohesive advice can aid informed decision making. Copyright © 2010 John Wiley & Sons, Ltd.
Lung function in children with repaired tracheo‐oesophageal fistula using the forced oscillation technique
Authors: Harrison Joanne , Martin Jessica , Crameri Joe , Robertson Colin F. , Ranganathan Sarath C.
Published: September 2010

Background

Tracheo‐oesophageal fistula (TOF) and oesophageal atresia (OA) are congenital anomalies commonly associated with pulmonary complications during early childhood. This study investigated the role of the forced oscillation technique (FOT) in assessing lung function in young children with repaired TOF/OA.

Methods

Forty children with repaired TOF/OA of median (range) age 8.0 (3.3–10.6) years, and 20 healthy children without TOF aged 6.1 (3.1–10.8) years were studied. FOT measurements were attempted in all subjects and spirometry only in those 6 years and above. Resistance and reactance (both hPasL−1) at 6 Hz (Rrs6 and Xrs6, respectively) and 8 Hz (Rrs8 and Xrs8) measured using FOT, and forced expired volume in 1 sec (FEV1), forced vital capacity, functional residual capacity, total lung capacity, and residual volume (all L) obtained from spirometry or plethysmography were compared with reference values and expressed as z‐scores.

Results

Technically acceptable measurements of Rrs6, Rrs8, Xrs6, Xrs8, Fdep, and Fres were obtained in 37 children with TOF and 20 healthy children without TOF, respectively. Those with TOF had significantly higher mean (SD) z‐scores for Rrs6 [0.99 (0.75)] versus healthy children without TOF [0.31 (0.69)] and lower mean (SD) z‐scores for Xrs6 [−1.04 (1.07)] versus healthy children without TOF [−0.34 (0.83)]. Spirometry was successful in 24 of the 29 with TOF in whom it was attempted and all healthy children without TOF. Mean (SD) z‐score for FEV1 was significantly lower in those with TOF [−0.86 (1.13)] versus healthy children without TOF [0.67 (0.54)]. z‐Scores for Rrs6 and FEV1 were significantly correlated (r = −0.49; P = 0.003).

Conclusions

Children with repaired TOF have diminished lung function compared with healthy children. FOT is sensitive and correlates well with standard spirometry. It can be used to measure lung function in younger children when spirometry is difficult to perform and should be considered as an objective method for monitoring clinical progress in young children with TOF. Pediatr Pulmonol. 2010;45:1057–1063. © 2010 Wiley‐Liss, Inc.
Experimental optimization of protein refolding with a genetic algorithm
Authors: Anselment Bernd , Baerend Danae , Mey Elisabeth , Buchner Johannes , Weuster‐Botz Dirk , Haslbeck Martin
Published: August 2010

Refolding of proteins from solubilized inclusion bodies still represents a major challenge for many recombinantly expressed proteins and often constitutes a major bottleneck. As in vitro refolding is a complex reaction with a variety of critical parameters, suitable refolding conditions are typically derived empirically in extensive screening experiments. Here, we introduce a new strategy that combines screening and optimization of refolding yields with a genetic algorithm (GA). The experimental setup was designed to achieve a robust and universal method that should allow optimizing the folding of a variety of proteins with the same routine procedure guided by the GA. In the screen, we incorporated a large number of common refolding additives and conditions. Using this design, the refolding of four structurally and functionally different model proteins was optimized experimentally, achieving 74–100% refolding yield for all of them. Interestingly, our results show that this new strategy provides optimum conditions not only for refolding but also for the activity of the native enzyme. It is designed to be generally applicable and seems to be eligible for all enzymes.
A lead discovery strategy driven by a comprehensive analysis of proteases in the peptide substrate space
Authors: Sukuru Sai Chetan K. , Nigsch Florian , Quancard Jean , Renatus Martin , Chopra Rajiv , Brooijmans Natasja , Mikhailov Dmitri , Deng Zhan , Cornett Allen , Jenkins Jeremy L. , Hommel Ulrich , Davies John W. , Glick Meir
Published: August 2010

We present here a comprehensive analysis of proteases in the peptide substrate space and demonstrate its applicability for lead discovery. Aligned octapeptide substrates of 498 proteases taken from the MEROPS peptidase database were used for the in silico analysis. A multiple‐category naïve Bayes model, trained on the two‐dimensional chemical features of the substrates, was able to classify the substrates of 365 (73%) proteases and elucidate statistically significant chemical features for each of their specific substrate positions. The positional awareness of the method allows us to identify the most similar substrate positions between proteases. Our analysis reveals that proteases from different families, based on the traditional classification (aspartic, cysteine, serine, and metallo), could have substrates that differ at the cleavage site (P1–P1′) but are similar away from it. Caspase‐3 (cysteine protease) and granzyme B (serine protease) are previously known examples of cross‐family neighbors identified by this method. To assess whether peptide substrate similarity between unrelated proteases could reliably translate into the discovery of low molecular weight synthetic inhibitors, a lead discovery strategy was tested on two other cross‐family neighbors—namely cathepsin L2 and matrix metallo proteinase 9, and calpain 1 and pepsin A. For both these pairs, a naïve Bayes classifier model trained on inhibitors of one protease could successfully enrich those of its neighbor from a different family and vice versa, indicating that this approach could be prospectively applied to lead discovery for a novel protease target with no known synthetic inhibitors.
Functional hot spots in human ATP‐binding cassette transporter nucleotide binding domains
Authors: Kelly Libusha , Fukushima Hisayo , Karchin Rachel , Gow Jason M. , Chinn Leslie W. , Pieper Ursula , Segal Mark R. , Kroetz Deanna L. , Sali Andrej
Published: August 2010

The human ATP‐binding cassette (ABC) transporter superfamily consists of 48 integral membrane proteins that couple the action of ATP binding and hydrolysis to the transport of diverse substrates across cellular membranes. Defects in 18 transporters have been implicated in human disease. In hundreds of cases, disease phenotypes and defects in function can be traced to nonsynonymous single nucleotide polymorphisms (nsSNPs). The functional impact of the majority of ABC transporter nsSNPs has yet to be experimentally characterized. Here, we combine experimental mutational studies with sequence and structural analysis to describe the impact of nsSNPs in human ABC transporters. First, the disease associations of 39 nsSNPs in 10 transporters were rationalized by identifying two conserved loops and a small α‐helical region that may be involved in interdomain communication necessary for transport of substrates. Second, an approach to discriminate between disease‐associated and neutral nsSNPs was developed and tailored to this superfamily. Finally, the functional impact of 40 unannotated nsSNPs in seven ABC transporters identified in 247 ethnically diverse individuals studied by the Pharmacogenetics of Membrane Transporters consortium was predicted. Three predictions were experimentally tested using human embryonic kidney epithelial (HEK) 293 cells stably transfected with the reference multidrug resistance transporter 4 and its variants to examine functional differences in transport of the antiviral drug, tenofovir. The experimental results confirmed two predictions. Our analysis provides a structural and evolutionary framework for rationalizing and predicting the functional effects of nsSNPs in this clinically important membrane transporter superfamily.
Prostate cancer risk and exposure to pesticides in British Columbia Farmers
Authors: Band Pierre R. , Abanto Zenaida , Bert Joel , Lang Barbara , Fang Raymond , Gallagher Richard P. , Le Nhu D.
Published: August 2010

BACKGROUND

Several epidemiologic studies have reported an increased risk of prostate cancer among farmers. Our aim was to assess the risk of developing prostate cancer in relation to exposure to specific active compounds in pesticides.

METHOD

A case–control approach was used with 1,516 prostate cancer patients and 4,994 age‐matched internal controls consisting of all other cancer sites excluding lung cancer and cancers of unknown primary site. Lifetime occupational history was obtained through a self‐administered questionnaire and used in conjunction with a job exposure matrix to estimate the participants' lifetime cumulative exposure to approximately 180 active compounds in pesticides. Conditional logistic regression was used to assess prostate cancer risk, adjusting for potential confounding variables and effect modifiers. These include age, ethnicity, alcohol consumption, smoking, education, and proxy respondent.

RESULTS AND CONCLUSIONS

The significant association between prostate cancer risk and exposure to DDT (OR = 1.68; 95% CI: 1.04–2.70 for high exposure), simazine (OR = 1.89; 95% CI: 1.08–3.33 for high exposure), and lindane (OR = 2.02; 95% CI: 1.15–3.55 for high exposure) is in keeping with those previously reported in the literature. We also observed a significant excess risk for several active ingredients that have not been previously reported in the literature such as dichlone, dinoseb amine, malathion, endosulfan, 2,4‐D, 2,4‐DB, and carbaryl. Some findings in our study were not consistent with those reported in the literature, including captan, dicamba, and diazinon. It is possible that these findings showed a real association and the inconsistencies reflected differences of characteristics between study populations. Prostate 71: 168–183, 2011. © 2010 Wiley‐Liss, Inc.
Monitoring of QoI fungicide resistance in Plasmopara viticola populations in Japan
Authors: Furuya Seiichi , Mochizuki Mai , Saito Seiya , Kobayashi Hironori , Takayanagi Tsutomu , Suzuki Shunji
Published: August 2010

BACKGROUND: The increasing occurrence of QoI fungicide resistance in Plasmopara viticola (Berk. & MA Curtis) Berl. & DeToni populations is becoming a serious problem in the control of grapevine downy mildew. In Japan, the existence of QoI‐fungicide‐resistant P. viticola was reported in 2009.

RESULTS: The QoI fungicide resistance in P. viticola samples collected from vineyards in Japan in 2008 and 2009 was monitored. Resistant P. viticola were detected in the regions where QoI fungicides have been introduced in accordance with the pest management programme, whereas in Hokkaido vineyards, where QoI fungicides have not yet been introduced, QoI‐fungicide‐resistant P. viticola were not found.

CONCLUSION: Japan comprises thousands of islands and is physically isolated from other countries by the sea. Monitoring the emergence, incidence and distribution of QoI fungicide resistance in P. viticola populations in Japan is necessary to improve pest management strategies for downy mildew disease in Japanese vineyards. Copyright © 2010 Society of Chemical Industry
Optimization of oxidative folding methods for cysteine‐rich peptides: a study of conotoxins containing three disulfide bridges
Authors: Steiner Andrew M. , Bulaj Grzegorz
Published: September 2010

The oxidative folding of small, cysteine‐rich peptides to selectively achieve the native disulfide bond connectivities is critical for discovery and structure‐function studies of many bioactive peptides. As the propensity to acquire the native conformation greatly depends on the peptide sequence, numerous empirical oxidation methods are employed. The context‐dependent optimization of these methods has thus far precluded a generalized oxidative folding protocol, in particular for peptides containing more than two disulfides. Herein, we compare the efficacy of optimized solution‐phase and polymer‐supported oxidation methods using three disulfide‐bridged conotoxins, namely µ‐SIIIA, µ‐KIIIA and ω‐GVIA. The use of diselenide bridges as proxies for disulfide bridges is also evaluated. We propose the ClearOx‐assisted oxidation of selenopeptides as a fairly generalized oxidative folding protocol. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Native chemical ligation of hydrophobic peptides in organic solvents
Authors: Dittmann Marc , Sauermann Jörg , Seidel Ralf , Zimmermann Wolfgang , Engelhard Martin
Published: September 2010

The application of chemistry to hydrophobic peptides and membrane‐spanning helices is hampered by the fact that they are only poorly soluble in aqueous buffers and that they have a tendency for aggregation. These properties lead to difficulties when purifying them after chemical synthesis and particularly interfere with native chemical ligation. Here, we describe native chemical ligation of model peptides in the organic solvent dimethylformamide (DMF) under anhydrous conditions. Best results concerning yields and complete solubility are obtained if thiophenole is used in the presence of LiCl. These conditions might be applicable also for the ligation of transmembrane helices. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Efficient synthesis of an (aminooxy) acetylated‐somatostatin derivative using (aminooxy)acetic acid as a ‘carbonyl capture’ reagent
Authors: Mezö Gábor , Szabó Ildikó , Kertész István , Hegedüs Rózsa , Orbán Erika , Leurs Ulrike , Bösze Szilvia , Halmos Gábor , Manea Marilena
Published: September 2010

Owing to the high chemoselectivity between an aminooxy function and a carbonyl group, oxime ligation is one of the most preferred procedures for the preparation of peptide conjugates. However, the sensitivity of (aminooxy)acetylated peptides to ketones and aldehydes makes their synthesis and storage difficult. In our study, we established the efficient synthesis of an (aminooxy)acetylated‐somatostatin derivative in the presence of free (aminooxy)acetic acid, which was used as a ‘carbonyl capture’ reagent in the final cleavage step. This (aminooxy)acetylated compound was further used for the chemoselective ligation (oxime bond formation) with daunorubicin and 4‐fluorobenzaldehyde leading to the formation of conjugates with potential applications in targeted cancer chemotherapy and positron emission tomography. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Magnetic, electric and dielectric properties of FeCo alloy nanoparticles dispersed in amorphous matrix
Authors: Thirumal E. , Prabhu D. , Chattopadhyay K. , Ravichandran V.
Published: August 2010

Nanocrystalline Fe53Co47 alloy was synthesized by a single‐step transmetallation chemical method at room temperature. The Fe53Co47 alloy nanoparticles of 77 and 47 wt% were dispersed in silica matrix by the sol–gel process using tetraethyl orthosilcate. Structural studies reveal that the as‐prepared alloy powders are in bcc phase and silica is in an amorphous state. The phase‐transition temperature and Mössbauer spectra analysis of the Fe–Co alloy establishes the homogeneous alloy formation. A saturation magnetization of 218 emu/g was obtained for pure FeCo alloy at room temperature. Scanning electron microscopic analysis demonstrates the hollow‐sphere morphology for FeCo alloy particles. Magnetic nanocomposite consisting of 47 wt% FeCo–silica shows enhanced thermal stability over the native FeCo alloy. Electrical and dielectric properties of 47 wt% FeCo–silica nanocomposites were investigated as a function of frequency and temperature. It was found that the dielectric constants and dielectric loss were stable throughout the measured temperature (310–373 K). Our results indicate that FeCo–silica nanocomposite is a promising candidate for high‐frequency applications.
PrOAlN dielectrics for metal insulator semiconductor stacks
Authors: Henkel Karsten , Torche Mohamed , Sohal Rakesh , Karavaev Konstantin , Burkov Yevgen , Schwiertz Carola , Schmeißer Dieter
Published: August 2010

This work focuses on praseodymium oxide films as a high‐k material on silicon and silicon carbide (SiC) in metal insulator semiconductor samples. The electrical results are correlated to spectroscopic findings on this material system. Strong interfacial reactions between the praseodymium oxide and the semiconductor as well as silicon inter‐diffusion into the high‐k material are observed. The importance of a buffer layer is discussed and its optimisation is addressed, too. In particular the improvement of the performance by the introduction of an aluminium oxynitride buffer layer, which acts as an inter‐diffusion barrier and reduces the leakage current, the interface state density and the equivalent oxide thickness is demonstrated.
Magnetism in graphite induced by irradiation of hydrogen or helium ions – A comparative study
Authors: Makarova Tatiana L. , Shelankov Andrei L. , Serenkov Igor T. , Sakharov Vladimir I.
Published: August 2010

To identify the origin of defect‐induced magnetism in ion‐irradiated graphite, a comparative study of samples of graphite irradiated with hydrogen H+ and helium He+ ions is performed. Directionally dependent magnetic properties, atomic/magnetic force microscopy studies suggest that the induced magnetic moments are located along the vertically aligned grain boundaries. Compared to the case of the hydrogen ion irradiation, the optimal helium irradiation dose is an order of magnitude lower. From this we conclude that the hydrogen chemistry is essentially irrelevant, and the ferromagnetic‐like response of the irradiated graphite is due to structural defects regardless of their origin.

magnified image

Surface of HOPG irradiated with H+ and He+ at similar doses.
Carbon nanotubes growth: From entanglement to vertical alignment
Authors: Esconjauregui Santiago , Fouquet Martin , Bayer Bernhard , Robertson John
Published: August 2010

By using oxidising environments during catalyst formation, SiO2‐supported thin Ni films restructure into small nanoparticles of reduced mobility that nucleate vertically‐aligned carbon nanotubes (CNTs) by base mode. Conversely, typical reducing environments yield entangled nanotubes only, which grow by tip mode. The selection of pretreatment environments proves control over nanotube morphology and growth mode, and can be of interest for the surface growth of other nanostructures.
Evaluation of defect concentration in doped SWCNT
Authors: Kalbac Martin , Kavan Ladislav
Published: August 2010

In the present study we analyze and discus Raman spectra of doped SWCNTs. We focus on the development of the integral area of the D mode (AD), the TG mode (ATG) and the G′ mode (AG′). It is shown that area of the D band is significantly attenuated in doped carbon nanotubes samples for both semiconducting and metallic tubes. A similar dependence on the doping as in the case of the area of the D mode was found also for the area of the TG and the G′ mode. The area of the G′ mode was found to be more significantly dependent on the electrode potential than the area of the TG mode. However, this difference is only small, hence the AD/AG′ and AD/ATG ratios give only slightly different results in evaluation of the amount of defects in doped SWCNT samples.
Tip‐enhanced Raman scattering along a single wall carbon nanotubes bundle
Authors: Peica Niculina , Thomsen Christian , Maultzsch Janina
Published: August 2010

Raman scattering is a common technique for studying carbon nanotubes due to the possibility to observe the radial breathing mode (RBM), which is used for identification of single wall carbon nanotubes “SWCNT.” Using tip‐enhanced Raman scattering (TERS) we show along a small SWCNTs bundle that the RBMs are well visible in near‐field, even if they are not observable in the far‐field. Different Raman intensities in TERS for the D, G, and 2D modes at six different positions along a SWCNTs bundle were observed. We discuss this strong dependence of the TERS signal on the position of the tip on the sample and on the distance between the tip and the sample.
A comparative study of field emission from NanoBuds, nanographite and pure or N‐doped single‐wall carbon nanotubes
Authors: Kleshch V. I. , Susi T. , Nasibulin A. G. , Obraztsova E. D. , Obraztsov A. N. , Kauppinen E. I.
Published: August 2010

Field emission characteristics of multi‐emitter flat cathodes prepared from NanoBuds, few‐layer graphite flakes (nanographite, NG) and pure or N‐doped single‐wall carbon nanotubes (SWNTs) have been examined. The cathodes demonstrated a low‐voltage electron emission with the threshold field values of few Volts per micron, which were ascribed to the high‐aspect ratio of nanocarbons. The films of NanoBuds and NG possess excellent emission pattern homogeneity with an emission site density of more than 105 cm−2. This is much higher than for cathodes made of conventional SWNT films. It was found that the achievable maximal current density depends on the type of carbon material and reaches 10 A/cm2 for NanoBuds film, while for the NG film cathodes, it is about one order of magnitude less. Possible mechanisms responsible for the experimentally observed differences are discussed. The materials examined are of great interest due to their high‐emission characteristics and are promising for the development of new types of vacuum electronic devices.
Benchmarking bucky gel actuators: Chemically modified commercial carbon nanotubes versus super‐growth carbon nanotubes
Authors: Biso Maurizio , Ansaldo Alberto , Futaba Don N. , Hata Kenji , Ricci Davide
Published: August 2010

Bucky gels are considered novel electro active polymers based on carbon nanotubes (CNTs). They are used to make electrochemical actuators that operate with a solid polymer electrolyte and so can work in air at low voltage (2–4 V) for long time with a maximum strain of approximately 1% and operating frequencies of a few tens of Hertz. It is reported in literature that the use of super‐growth carbon nanotubes (SG‐CNTs) affords the preparation of a composite with increased actuation performance that may considered the ‘benchmark’ material. We have recently shown a chemical route to modify single walled carbon nanotubes (SW‐CNTs) with aromatic diamines (SW‐amide) that significantly enhances the performance of bucky gel actuators through increasing the binding between CNTs. In this paper we compare the actuation performance of bucky gels made using chemically modified SW‐CNTs with the one achieved using pristine SG‐CNTs. The unique properties of SG‐CNTs allow the preparation of actuators that outperform the ones made from pristine commercial CNTs in strain‐charge and strain‐frequency response but when SW‐amide based actuators are compared with those made from SG‐CNTs they show similar performances that stem from the increased binding between CNTs induced by the chemical modification.
Nuclear magnetic resonance and magnetization study of surfactant‐coated epsilon‐Co nanoparticles
Authors: Hines William , Budnick Joseph , Perry David , Majetich Sara , Booth Ryan , Sachan Madhur
Published: August 2010

A combination of 59Co spin‐echo nuclear magnetic resonance (NMR) and dc magnetization measurements have been carried out on two samples of surfactant‐coated Co nanoparticles in disordered assemblies; 6.5 nm diameter ε‐Co and 12 nm diameter hcp‐Co. The ε‐Co nanoparticles exhibit superparamagnetic behavior with a blocking temperature TB = 70 K, while the hcp‐Co nanoparticles remain ferromagnetic up to room temperature. In addition, the initial susceptibility for the ε‐Co nanoparticles can be described by the Curie–Weiss law with a negative Θ = −158 K. The NMR signal from the hcp‐Co sample is strong at 77 K with no applied magnetic field; the spectra are straightforward and similar to that for bulk hcp Co. However, the NMR signal from the ε‐Co sample is not detectable at 77 K, even with fields up to 7.5 kOe. A NMR signal appears at 4.2 K; the echo amplitude increases dramatically with applied field. The spectra, which must be corrected for T2 effects, are quite broad and characteristic of the small particle size. Due to the broadening, there were no observable spectral features which could be assigned to the two Co sites in crystalline ε‐Co. The results are discussed in the light of interparticle interactions which reduce the initial susceptibility and lead to negative Θ‐values. Estimates are given for the magnetic dipolar and magnetocrystalline anisotropy energies of the particles in both samples.
First‐principles calculations of atomic and electronic properties of ZnO nanostructures
Authors: Xu H. , Fan W. , Fang D. , Rosa A. L. , Frauenheim Th. , Zhang R. Q.
Published: September 2010

We employ density‐functional theory within the generalized‐gradient approximation to investigate the formation energies and atomic and electronic structure of ZnO nanowires and nanotubes (NTs). We find that relaxations on the facets of the bare wires are very similar to those in nonpolar $(10{\bar {1}}0)$ surfaces and play an important role in stabilizing the nanowires. All bare wires are found to be semiconducting, with band gaps larger than that in bulk ZnO. We further investigated hydrogen and water adsorption on ZnO nanowires. We find that the electronic structure of ZnO nanowires can be tuned by hydrogen adsorption and that adsorption of water leads to dissociation of a half‐monolayer. Next, the stability of ZnO NTs has been investigated. We show that multiwall NTs are more stable than single‐walled tubes. Finally, point defects in ZnO NTs have been investigated using spin‐polarized calculations. All calculations were shown to introduce defect levels in the band gap, thus changing the electronic structure of the NTs drastically.
An automated velocity dealiasing method based on searching for zero isodops
Authors: Li Nan , Wei Ming
Published: August 2010

A new automated velocity dealiasing method based on zero isodop searching has been developed primarily for linear wind fields. Its essence is to partition the radial velocity field obtained with a Doppler radar into two distinct regions of opposite velocity signs by two zero isodops. Zero isodops are searched point by point from the radar origin to the maximum detection range, and the accepted sign of each region separated by the zero isodops is determined. After that, the velocity sign at each gate is compared with the accepted sign of the region wherein the gate is. If they are consistent, the velocity is true; otherwise it is dealiased. Dealiasing results in real cases indicate that the new algorithm is practicable and effective, especially on aliasing lack of references affected by discontinuous echo or range folding, which is difficult for traditional methods of space continuity checking. Copyright © 2010 Royal Meteorological Society
Change detection in the Cox Proportional Hazards models from different reliability data
Authors: Li Zhiguo , Zhou Shiyu , Sievenpiper Crispian , Choubey Suresh
Published: August 2010

The Proportional Hazards (PH) model is an important type of failure time regression model which relates the occurrence probability of critical failures to influential factors. However, little research work has been done on detecting changes in the PH models fitted based on different sets of reliability data. This paper develops the methods for change detection in the Cox PH models, also known as Semiparametric PH model, for reliability prediction and/or assessment of the time‐to‐failure data collected from different subjects. The effectiveness of the developed methods is illustrated through numerical studies and real‐world data analysis. The developed technique possesses wide applicability to the systems and processes where the Cox PH model fits the reliability data well. Copyright © 2010 John Wiley & Sons, Ltd.
Multiresponse optimization using multivariate process capability index
Authors: Awad Mahmoud I. , Kovach Jamison V.
Published: August 2010

Robust design is an efficient method for product and process improvement which combines experimentation with optimization to create a system that is less sensitive to uncontrollable variation. In this article, a simple and integrated modeling methodology for robust design is proposed. This methodology achieves the robustness objective function and input variables constraints simultaneously. The objective function is written in terms of the multivariate process capability vector (MCpm) of several competing features of the system under study. The proposed methodology is applicable to general functions of the system performance with random variables. The effectiveness of the methodology is verified using two real‐world examples which are compared with those of other robust design methods. Copyright © 2010 John Wiley & Sons, Ltd.