bluuebunny/crossref_metadata_2025 huggingface dataset:
Five backpacker tourist enclaves
Authors: Howard Robert W.
Published: March 2007

Little is known about backpacker enclaves and the concept itself needs clarification. The present study analysed the concept and surveyed the characteristics and local impacts of five varied enclaves in four nations. Most have a concentration of tourist businesses and are centrally located near transport and major tourist attractions. Tourist behaviour in the different enclaves is fairly similar. Tourists use them for convenience and inexpensive accommodation, to collect travel information and to relax and socialise. Some enclaves are nightlife centres for locals and are tourist attractions, with some foreign tourists visiting mainly to party and locals visiting to see the strange foreigners. Host‐nation culture also affects some enclave characteristics and local impacts. The present analysis and data provide a sound and useful concept of a backpacker enclave and its characteristics. Copyright © 2007 John Wiley & Sons, Ltd.
What does the consumer want from a DMO website? A study of US and Canadian tourists' perspectives
Authors: Choi Soojin , Lehto Xinran Y. , Oleary Joseph T.
Published: March 2007

Destination marketing organisations (DMOs) are facing intriguing challenges to provide quality information online in an era of information overload. Insufficient knowledge of tourist's online information preferences and search behaviour has hindered them from effective information management. This research aimed to examine consumers' perspectives of the information role of the DMOs and their preferences and attitudes towards what constitute engaging and relevant Web contents and functionalities for a DMO website. The results suggested that tourists' preference of information content varied across the different levels of DMO websites (country, state/province and city). In addition, the study revealed that travellers' information needs and behaviour change over the entire information consumption process, which include the before, during and post‐trip period. Implications for DMOs were discussed at the end. Copyright © 2007 John Wiley & Sons, Ltd.
Tourist shopping experiences and satisfaction
Authors: Tosun Cevat , Temizkan S. Pinar , Timothy Dallen J. , Fyall Alan
Published: March 2007

This paper examines tourists' perceived satisfaction with local shopping culture, staff service quality, product value and reliability, physical features of shops, payment methods, and other shopping and shop attributes with special reference to the region of Cappadocia, Turkey. A survey questionnaire was designed and conducted with tourists visiting the region on a guided tour. It was found that the respondents recorded different levels of satisfaction with various attributes of shops and shopping. Based on the research results, it is suggested that providing a higher level of shopping experience for tourists and increasing the contribution of shopping to the regional economy requires supporting indigenous local people via various fiscal and educational instruments to continue producing and retailing authentic handicrafts and souvenir goods. It is believed that this not only is necessary for the achievement of higher levels of tourist satisfaction and greater economic benefits for the local economy but also for achieving the ultimate goal of sustained and sustainable tourism development. Copyright © 2007 John Wiley & Sons, Ltd.
Swimming with captive dolphins: current debates and post‐experience dissonance
Authors: Curtin Susanna , Wilkes Keith
Published: March 2007

Dolphins have widespread contemporary appeal and anthropomorphic social representations of dolphins have fuelled a growing desire in tourist populations to seek interaction with them. This paper is concerned with the staged performance of swim‐with‐dolphin interaction programmes in aquaria. Qualitative interviews with tourists who have swum with captive dolphins identified their immediate recollections and stressed the grace, size and power of dolphins, but also a belief that the experience was too staged, too short and too expensive. Post‐purchase dissonance focused on concerns with the size of enclosures and about captivity, too many tricks, limited interpretation and unfulfilled expectations of a quality interaction. Copyright © 2007 John Wiley & Sons, Ltd.
Structure Design of Novel Hyperbranched Polycarbosilazanes: Synthesis and Characterization
Authors: Zhang Guo‐Bin , Fan Xiao‐Dong , Kong Jie , Liu Yu‐Yang , Wang Min‐Chang , Qi Zhu‐Chai
Published: March 2007

Three novel hyperbranched polycarbosilazanes were synthesized via hydrosilylation reaction and characterized by FT‐IR, 1H NMR, 13C NMR, 29Si NMR, and laser light scattering. First, one AB4 type monomer bis(N,N‐diallylamino)‐methylsilane (M1) and two AB2 type monomers (N,N‐diallylamino)‐dimethylsilane (M2) and N,N‐bis (dimethylsilyl)‐allylamine (M3) were prepared by aminolysis of MeHSiCl2 and Me2HSiCl with diallylamine and allylamine. Then monomers were polymerized into hyperbranched polycarbosilazanes via hydrosilylation reaction using H2PtCl6 as the catalyst. The measurements indicate that α‐hydrosilylation mainly occurs during the polymerization and the polymers synthesized consist of SiNC linkages with hyperbranched architectures carrying a large amount of functional vinyl or SiH end groups. The molecular weights ($\overline M _{\rm w} $) of the three polymers were found to be 13 500, 4 600, and 3 900 g · mol−1, respectively.

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Dispersion‐Polymerized Carbon Nanotube/Poly(methyl methacrylate) Composite Particles and their Electrorheological Characteristics
Authors: Kim Sung Tae , Lim Jae Yun , Park Bong Jun , Choi Hyoung Jin
Published: March 2007

An in situ dispersion polymerization method was adopted to synthesize particulate composites of MWNTs and PMMA, mainly for the investigation of their electrorheological characteristics. The morphology of the PMMA microparticles synthesized in the presence of the MWNTs was examined by both SEM and TEM, showing that the MWNTs were not only grafted onto the surface of the PMMA microbeads, but were also embedded inside the synthesized microbeads. The synthesized MWNT/PMMA particulate composites were also characterized by zeta‐potential measurements and TGA for electric and thermal stability studies, respectively. A suspension of the MWNT/PMMA microparticles dispersed in silicone oil was found to show enhanced electrorheological properties on the increase of shear stresses when subjected to an external electric field, exhibiting high yield stresses despite the tiny amount of the MWNT associated.

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Viscous behaviour of dry sand
Authors: Pham Van Bang D. , Di Benedetto H. , Duttine A. , Ezaoui A.
Published: March 2007

Tests on air‐dried Hostun sand were performed on a newly developed triaxial apparatus, which allows static and dynamic measurements at ‘Département Génie Civil et Bâtiment’ (DGCB) of ENTPE. The prototype was designed to perform tests in order to investigate the viscous effects of sand from small strain (some 10−5m/m)
up to intermediate strain (some 10−3m/m). The accuracy of the measuring system is ensured by the use of local non‐contact displacements transducers and by the use of an internal load cell. The viscous behaviour of sand is experimentally studied for loose and dense specimens for confining pressure values from 80 up to 400 kPa and considering different histories of loading. Three types of viscous loading: creep periods; stress relaxation periods; and paths with stepwise changes in the strain rate are specifically analysed. The proposed viscous modelling is issued from a three‐component general framework and is able to reproduce the experimental observations. More specifically, the peculiar behaviour of sand observed during a stepwise increase or decrease in the strain rate is detailed and modelled by the viscous evanescent (VE) model, developed at DGCB/ENTPE. Based on the three types of viscous tests, a simple relation is finally proposed for the viscous parameters of the VE model. Comparisons between data and simulations validate the approach. Copyright © 2007 John Wiley & Sons, Ltd.
Fractional anisotropy and mean diffusivity: comparison between 3.0‐T and 1.5‐T diffusion tensor imaging with parallel imaging using histogram and region of interest analysis
Authors: Fushimi Yasutaka , Miki Yukio , Okada Tsutomu , Yamamoto Akira , Mori Nobuyuki , Hanakawa Takashi , Urayama Shin‐ichi , Aso Toshihiko , Fukuyama Hidenao , Kikuta Ken‐ichiro , Togashi Kaori
Published: March 2007

We performed a comparison study focusing on differences in fractional anisotropy (FA) and mean diffusivity (MD) between 3‐T and 1.5‐T diffusion tensor imaging (DTI) with parallel imaging. Thirty healthy volunteers underwent DTI with an eight‐channel phased‐array coil at both 3 T and 1.5 T. Histogram and region of interest (ROI) analyses were performed. Paired t tests were applied for statistical analysis. Signal‐to‐noise ratios of these regions were also measured. For histogram analysis, peak location of FA was significantly lower at 3 T than at 1.5 T (P = 0.04). Mean FA was significantly higher at 3 T than at 1.5 T (P = 0.002). Peak location of MD was significantly lower at 3 T than at 1.5 T (P < 0.001). Mean MD was significantly lower at 3 T than at 1.5 T (P < 0.001). In ROI analysis, FA was significantly larger at 3 T than at 1.5 T in the centrum semiovale (P < 0.001), middle cerebellar peduncle (P < 0.001), cerebral peduncle (P = 0.006), posterior limb of the internal capsule (P = 0.007), genu (P < 0.001) and splenium (P < 0.001). FA was significantly lower at 3 T than at 1.5 T in the globus pallidus (P < 0.001). MD was significantly smaller at 3 T than at 1.5 T in the globus pallidus (P = 0.007), thalamus (P < 0.001), centrum semiovale (P < 0.001), middle cerebellar peduncle (P < 0.001), cerebral peduncle (P = 0.01), posterior limb of the internal capsule (P < 0.001), genu (P = 0.01) and splenium (P < 0.001). Significant differences in FA and MD exist between 3 T and 1.5 T for whole‐brain histogram analysis and ROI analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Automated tissue segmentation and blind recovery of1H MRS imaging spectral patterns of normal and diseased human brain
Authors: Du Shuyan , Mao Xiangling , Sajda Paul , Shungu Dikoma C.
Published: March 2007

Constrained non‐negative matrix factorization (cNMF) with iterative data selection is described and demonstrated as a data analysis method for fast and automatic recovery of biochemically meaningful and diagnostically specific spectral patterns of the human brain from1H MRS imaging (1H MRSI) data. To achieve this goal, cNMF decomposesin vivomultidimensional1H MRSI data into two non‐negative matrices representing (a) the underlying tissue‐specific spectral patterns and (b) the spatial distribution of the corresponding metabolite concentrations. Central to the proposed approach is automatic iterative data selection which uses prior knowledge about the spatial distribution of the spectra to remove voxels that are due to artifacts and undesired metabolites/tissues such as the strong lipid and water components. The automatic recovery of diagnostic spectral patterns is demonstrated for long‐TE1H MRSI data on normal human brain, multiple sclerosis, and serial brain tumor. The results show the ability of cNMF with iterative data selection to automatically and simultaneously recover tissue‐specific spectral patterns and achieve segmentation of normal and diseased human brain tissue, concomitant with simplification of information content. These features of cNMF, which permit rapid recovery, reduction and interpretation of the complex diagnostic information content of large multi‐dimensional spectroscopic imaging data sets, have the potential to enhance the clinical utility ofin vivo1H MRSI. Copyright © 2007 John Wiley & Sons, Ltd.
Compositional analysis of intact alkyl esters in leaf epicuticular wax of swede by capillary gas chromatography and electron‐impact mass spectrometry
Authors: Shepherd T. , Robertson G. W. , Griffiths D. W.
Published: March 2007

A method for the separation and identification of complex mixtures of more than 50 different intact esters in epicuticular wax of swede, Brassica napus var. rapifera cv. Doon Major, using combined gas chromatography‐mass spectrometry (GC‐MS) has been developed. The esters were separated at temperatures of up to 350°C by automatic pressure programming (for capillary GC) or by manually increasing helium carrier gas pressure (for GC‐MS) in order to maintain flow at high temperatures. Esters in the range C41‐C50 were detected, with regular repeating acid/alcohol combinations. Individual acid and alcohol moieties were identified from [RCO2H2]+ ions in the mass spectra of intact esters and, following trans‐esterification and silylation, from the mass spectral and chromatographic characteristics of the methyl esters of the acid components (C14‐C23) and trimethylsilyl derivatives of the alcohol components (C23‐C31). The major compounds were doubly branched C44 and C46 esters, composed of anteiso‐C17/anteiso‐C27 (32.7%), anteiso‐C17/anteiso‐C29 (11.9%) and anteiso‐C19/anteiso‐C27 (13.1%) acid/alcohol combinations, respectively, singly branched C43 and C45 esters, composed of n‐C16/anteiso‐C27 (8.5%), anteiso‐C17/n‐C26 (3.9%), n‐C18/anteiso‐C27 (6.8%), anteiso‐C17/n‐C28 (2.3%) and anteiso‐C19/n‐C26 (1.6%), were minor components.
Use of a porous graphitic carbon column to separate isomers of piperidino‐type chromone alkaloids
Authors: Houghton Peter J. , Woldemariam Tibebe Z.
Published: March 2007

A liquid chromatography procedure which rapidly separates the two isomers of schumannificine and N‐methylschumannificine, chromone alkaloids isoilated from Schumanniophyton magnificum (Rubiaceae), is described. The procedure uses a porous graphitic carbon high performance liquid chromatographic column and is compared with other chromatographic and chemical methods which were tried unsuccessfully. The method was adapted in an attempt to prepare the individual isomers of schumannificine and N‐methylschumannificine in mg amounts but interconversion of the isomers in aqueous medium was shown to occur too rapidly for this to be feasible.
Synthesis and enantiodifferentiation of riesling acetals
Authors: Dollmann B. , Full G. , Schreier P. , Winterhalter P. , Güntert M. , Sommer H.
Published: March 2007

The cyclic acetals 1b/c were prepared in a biomimetic‐type reaction via the Mosher‐esters 5a/b of their natural precursor 2,6,10,10‐tetramethyl‐1‐oxaspiro[4.5]dec‐6‐ene‐2,8‐diol (6) which were available from 3,4‐didehydro‐β‐ionone (2) by photosensitized oxidation and subsequent reduction with thiourea. The racemic cis‐diols 3 so‐obtained were esterified with (–)‐α‐methoxy‐α‐trifluoromethyl‐phenylacetyl chloride and the resulting diastereo‐meric esters (4a/b) isolated in pure form (diastereomeric excess >95%) by preparative high performance liquid chromatography. Configuration at C‐6 was determined after bio‐oxidative cleavage of 4a/b to dehydrovomifo‐liols 8a/b. The hemiacetals 5a/b obtained from esters 4a/b by hydrogenation (Pd/BaSO4) were subjected to thermal treatment at pH 3 yielding two optically enriched isomers of Riesling acetal which were subsequently obtained in optically pure form by preparative gas chromatography using a modified cyclodextrin column. Their relative configuration was established by NOE‐experiments. In addition, the structures and the heats of formation of the different diastereomers were calculated using a force field program and the semi‐empirical MNDO, AMI and PM3 methods. The absolute configurations were found from the results of the NOESY experiment, the calculations and the stereoselective synthesis. Riesling acetal enantiomers differed distinctly in their odour properties. (+)‐Riesling acetal 1b showed a weak “woody, fruity, ionone, flowery” note, whereas the (‐)‐isomer 1c exhibited a slight “camphoraceous, flowery” note. Enantiodifferentiation of 1b/c in a number of natural sources with the help of multidimensional gas chromatography (DB‐Wax/C‐Dex B) revealed a nearly racemic composition of 1b/c.
Prosapogenins from Dodonaea attenuata
Authors: Han Andrew Y. T. , Van Gorkom Leon , McFarlane Ian J. , Barrow Kevin D.
Published: March 2007

Saponins have been extracted from the seed of Dodonaea attenuata and converted to prosapogenins by mild acid hydrolysis. Partially acetylated derivatives of the sapogenin, R1‐barrigenol, were characterized by extensive two dimensional nuclear magnetic resonance spectroscopy. The complete assignments of 1H and 13C resonances and nuclear Overhauser effects of these partly acetylated sapogenins has allowed a straightforward assignment of the structures of the prosapogenins, including the location of the individual ester groups and the presence of artefacts from the acidic hydrolysis conditions.
Capillary electrophoresis: A new technique in the analysis of plant secondary metabolites
Authors: Tomás‐Barberán F. A.
Published: March 2007

The possibilities and applications of capillary electrophoresis (CE) as an analytical technique for plant secondary metabolites are reviewed. Applications of both capillary zone electrophoresis and micellar electrokinetic capillary chromatography for this purpose are described. CE is compared with high pressure liquid chromato‐graphy (HPLC) as an analytical technique, and the advantages and criticisms of CE are described. The effects of the applied voltage, capillary temperature, electrolyte concentration and nature (complexing or non‐complexing buffers), buffer pH, micelle concentration and nature (sodium dodecyl sulphate or cetyltrimethylammonium bromide and the addition of organic modifiers to the running buffer (organic solvents, cyclodextrins, urea, cholate) on the parameters of separation and resolution of different secondary metabolites are discussed. The applications of CE to the analysis of flavonoid aglycones and glycosides, phenolic acids, quinones, coumarins, alkaloids, capsacinoids, glucosinolates, polyamines, monoterpenes, diterpenes, phytoecdysteroids, cardiac glycosides and saponins are shown. It is concluded that CE is a very promising analytical technique in the analysis of plant secondary metabolites, and it will become an indispensable tool, together with HPLC and gas liquid chromatography, in phytochemical laboratories since these techniques are in many ways complementary, and problems that are difficult to solve by HPLC can often be solved using CE.
Capillary electrophoresis of isoquinoline alkaloids from Chelidonium Majus L.
Authors: Pietta P. G. , Mauri P. L. , Gardana C. , Colombo M. L. , Tomè F.
Published: March 2007

The determination of six different isoquinoline alkaloids from Chelidonium majus (leaves and roots) using capillary electrophoresis is described. Analyses were performed on fused silica capillaries with 66 mM phosphate buffer at pH 2.4 containing 40% methanol. The analytes were monitored by on‐line ultraviolet (UV) detection to identify sanguinarine, chelerythrine, berberine and chelidonine. Both coptisine and DL‐stylopine were isolated by semi‐preparative high performance liquid chromatography (HPLC), and their structure assessed by UV and mass spectrometry. Capillary electrophoresis is confirmed as a useful complementary technique to HPLC.
Aspects of the extraction and purification of solasodine from Solanum aculeastrum tissues
Authors: Drewes F. E. , Van Staden J.
Published: March 2007

A protocol has been developed for the extraction and purification of solasodine from plant material to complement the use of benzoylation for derivatization of the compound prior to high performance liquid chromatographic (HPLC) determination. Solasodine glycosides were extracted in 80% ethanol, the samples defatted with chloroform and then hydrolysed with 0.5 M hydrochloric acid. The extracts were washed with ethyl acetate, prior to increasing the pH to between 8 and 9, whereafter solasodine was extracted with chloroform. Flash chromatography using a 15 cm silica gel column was necessary for purification of the extracts, which were then benzoylated and subjected to HPLC. In green Solanum aculeastrum Dun. berries, 0.016% solasodine was detected, whereas in callus cultures of the same species no solasodine was detectable.
Identification of lipophilic flavonols by a combination of chromatographic and spectral techniques
Authors: Greenham Jenny , Williams Christine , Harborne Jeffrey B.
Published: March 2007

Isocratic and gradient elution high performance liquid chromatographic techniques are compared for separating different methylated and isoprenylated flavonols. The identification of individual flavonols from their isomers, based on retention times, thin layer chromatographic data and ultraviolet spectroscopy is discussed. These data are provided for 23 kaempferol, quercetin and myricetin O‐methyl ethers, for seven C‐methyl ethers and 15 isoprenylated derivatives.
Permeation chromatography on extracted Wolffia
Authors: Ehwald Rudolf , Klein Petra , Jungnickel Fritz , Dongowski Gerhard
Published: March 2007

Vesicular packing materials (VP) formed by the cell wall frame of denaturated and extracted Wolffia arrhiza and W. columbiana were investigated for possible applications in permeation chromatography. Two types of VP were studied: W0, being fronds extracted with ethanol and water, and W1, obtained from W0 by treatment with pancreatic enzymes in order to remove the insoluble protoplast residues. The cell wall material of W. arrhiza is characterized by a high content of pectin which is rich in homogalacturonan with low contents of L‐rhamnose, D‐galactose and L‐arabinose, and a low degree of esterification. In permeation chromatography on both W0 and W1, excluded components formed a sharp peak at an elution volume which was 26‐30% of the total bed volume. The critical size, in terms of Stokes' diameter, for the exclusion of macromolecules by W0 is about 5 nm, and this allows for complete exclusion of most proteins. At linear flow rates below 0.1 mL/cm2/min the column length necessary for complete separation of sugars or salts from excluded macromolecules may be less than 10 cm. Because of their smaller particle size the materials prepared from W. columbiana showed a smaller peak variance for permeable compounds. The potentially low price of the W0 material suggests its use as an alternative to gel filtration media for the fast removal of low molecular weight solutes from proteins and other hydrophilic colloidal materials on a technical scale.
Stereoisomeric flavour compounds. LXX: 1‐p‐menthene‐8‐thiol: Separation and sensory evaluation of the enantiomers by enantioselective gas chromatography‐olfactometry
Authors: Lehmann Detmar , Dietrich Armin , Hener Uwe , Mosandl Armin
Published: March 2007

The gas chromatographic separation of the 1‐p‐menthene‐8‐thiol enantiomers has been achieved using heptakis(2,3‐di‐O‐methyl‐6‐O‐TBDMS)‐β‐cyclodextrin as the chiral stationary phase in enantioselective gas chromatography. The sensory evaluation of the pure enantiomers has been realized by enantioselective gas chromatography‐olfactometry. (R)‐1‐p‐menthene‐8‐thiol was found to be of formative influence on the natural odour of grapefuit whilst the odour of the (S)‐enantiomer was weak and non‐specific.
13C‐nuclear magnetic resonance spectra of some andrographolide derivatives
Authors: Fan Dajing , Wu Xiaoyun , Qin Guowei
Published: March 2007

The 13C‐nuclear magnetic resonance spectra of some andrographolide derivatives have been assigned based on two‐dimensional correlation spectroscopy (COSY) and correlation via long‐range coupling (COLOC) spectra and comparison with known compounds. The assignment of triacetate of andrographolide, reported in literature, has been revised.
Cyanide content of the leaves and stems of edible aroids
Authors: Bradbury J. Howard , Egan Sylvia V. , Matthews Peter J.
Published: March 2007

The edible aroids taro (Colocasia esculenta), tannia (Xanthosoma violaceum), giant taro (Alocasia macrorrhizos), giant swamp taro (Cyrtosperma chamissonis) and elephant foot yam (Amorphophallus paeonifolius) have been shown to contain varying amounts of cyanide in their leaves and stems using a screening assay and a more accurate acid hydrolysis method. The cyanogenic glucoside triglochinin (previously identified in giant taro) was found to be less stable to acid hydrolysis (requiring only 15 min) compared with 50 min hydrolysis for linamarin and lotaustralian (from cassava) under the same experimental conditions. The amounts of cyanide present in the leaves (0‐3 mg HCN/100 g fresh weight) and in the stems (0—0.3 mg HCN/100 g fresh weight) of Colocasia and Xanthosoma are only about 1‐5% of that found in cassava leaves and tubers and are not a cause for concern for human nutrition. Cyrtosperma stems and Amorphophallus leaves contain only small amounts of cyanide. In contrast, all Alocasia varieties contained much more cyanide in leaves (2‐30 mg HCN/100 g fresh weight) and in stems (0.5‐4 mg HCN/100 g fresh weight).
Identification of bioactive metabolites from the bark of Pericopsis (Afrormosia) laxiflora
Authors: Tringali Corrado
Published: March 2007

The α‐methyldeoxybenzoins angolensin, 2‐O‐methyl‐angolensin and the pterocarpan maackiain (demethylpterocarpin) have been isolated by bioactivity‐guided fractionation (brine shrimp test) from the bark of the medicinal African plant, Pericopsis (Afrormosia) laxiflora.
Layer effects of photovoltaic heterojunction of fully conjugated heterocyclic aromatic rigid‐rod polymer poly‐p‐phenylenebenzobisoxazole
Authors: Huang Jen‐Wei , Bai Shih Jung
Published: March 2007

Poly‐p‐phenylenebenzobisoxazole (PBO) contains a fully conjugated rod‐like backbone entailing excellent optoelectronic properties and superior stabilities. Poly(2,3‐dihydrothieno‐1,4‐dioxin):polystyrenesulfonate (PEDOT:PSS) is a hole transferring medium, which was spun into a thin‐film between PBO and indium‐tin‐oxide to facilitate photovoltaic (PV) effect by forming a donor‐acceptor interlayer to separate and to transport photoinduced charges. Optimum PBO thickness for PV heterojunctions was about 71 nm at which the hole transferring PEDOT:PSS generated the maximum short circuit current (Isc) at a thickness of 115 nm. By using a layer of lithium fluoride (LiF) as an electron transferring layer adhering to Al cathode, the most open circuit voltage (Voc) and Isc were achieved with a LiF thickness of 1–2 nm because of possible electric dipole effect leading to an increase of Voc from 0.7 to 0.92 V and of Isc from about 0.1 to 0.2 μA. No PV response was observed for all PBO homojunctions because of insufficient exciton separation into electrons and holes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 988–993, 2007
Conformational states and folding pathways of peptides revealed by principal‐independent component analyses
Authors: Nguyen Phuong H.
Published: March 2007

Principal component analysis is a powerful method for projecting multidimensional conformational space of peptides or proteins onto lower dimensional subspaces in which the main conformations are present, making it easier to reveal the structures of molecules from e.g. molecular dynamics simulation trajectories. However, the identification of all conformational states is still difficult if the subspaces consist of more than two dimensions. This is mainly due to the fact that the principal components are not independent with each other, and states in the subspaces cannot be visualized. In this work, we propose a simple and fast scheme that allows one to obtain all conformational states in the subspaces. The basic idea is that instead of directly identifying the states in the subspace spanned by principal components, we first transform this subspace into another subspace formed by components that are independent of one other. These independent components are obtained from the principal components by employing the independent component analysis method. Because of independence between components, all states in this new subspace are defined as all possible combinations of the states obtained from each single independent component. This makes the conformational analysis much simpler. We test the performance of the method by analyzing the conformations of the glycine tripeptide and the alanine hexapeptide. The analyses show that our method is simple and quickly reveal all conformational states in the subspaces. The folding pathways between the identified states of the alanine hexapeptide are analyzed and discussed in some detail. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Free energy landscape of a biomolecule in dihedral principal component space: Sampling convergence and correspondence between structures and minima
Authors: Maisuradze Gia G. , Leitner David M.
Published: March 2007

Dihedral principal component analysis (dPCA) has recently been developed and shown to display complex features of the free energy landscape of a biomolecule that may be absent in the free energy landscape plotted in principal component space due to mixing of internal and overall rotational motion that can occur in principal component analysis (PCA) [Mu et al., Proteins: Struct Funct Bioinfo 2005;58:45–52]. Another difficulty in the implementation of PCA is sampling convergence, which we address here for both dPCA and PCA using a tetrapeptide as an example. We find that for both methods the sampling convergence can be reached over a similar time. Minima in the free energy landscape in the space of the two largest dihedral principal components often correspond to unique structures, though we also find some distinct minima to correspond to the same structure. Proteins 2007. © 2007 Wiley‐Liss, Inc.
An unsuspected ecdysteroid/steroid phosphatase activity in the key T‐cell regulator, Sts‐1: Surprising relationship to insect ecdysteroid phosphate phosphatase
Authors: Davies Lyndsay , Anderson Ian P. , Turner Philip C. , Shirras Alan D. , Rees Huw H. , Rigden Daniel J.
Published: March 2007

The insect enzyme ecdysteroid phosphate phosphatase (EPP) mobilizes active ecdysteroids from an inactive phosphorylated pool. Previously assigned to a novel class, it is shown here that it resides in the large histidine phosphatase superfamily related to cofactor‐dependent phosphoglycerate mutase, a superfamily housing notably diverse catalytic activities. Molecular modeling reveals a plausible substrate‐binding mode for EPP. Analysis of genomic and transcript data for a number of insect species shows that EPP may exist in both the single domain form previously characterized and in a longer, multidomain form. This latter form bears a quite unexpected relationship in sequence and domain architecture to vertebrate proteins, including Sts‐1, characterized as a key regulator of T‐cell activity. Long form Drosophila melanogaster EPP, human Sts‐1, and a related protein from Caenorhabditis elegans have all been cloned, assayed, and shown to catalyse the hydrolysis of ecdysteroid and steroid phosphates. The surprising relationship described and explored here between EPP and Sts‐1 has implications for our understanding of the function(s) of both. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Luminescence characteristics of LiCaAlF6:Eu phosphor
Authors: Aghalte G. A. , Omanwar S. K. , Moharil S. V.
Published: March 2007

A simple method for preparing LiCaAlF6:Eu2+ phosphor is reported. Photoluminescence (PL) and thermoluminescence (TL) studies were carried out. The TL sensitivity of the phosphor is nearly twice that of CaSO4:Dy TLD phosphor. Several other properties required for TL dosimetry are superior as well. It is suggested that the phosphor can be a suitable replacement for CaSO4:Dy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low temperature photoluminescence of pure and doped paratellurite (TeO2) crystals
Authors: Dafinei Ioan , Dujardin Christophe , Longo Egidio , Vignati Marco
Published: March 2007

Photoluminescence measurements aimed at defining the precise nature of scintillation reported in paratellurite (TeO2) crystals [Coron et al., Nucl. Instrum. Methods Phys. Res. A 520, 159 (2004)] are presented. Measurement results are discussed for TeO2 crystal samples (pure and Mg, Mn, Nb, Zr doped) studied for their photoluminescence properties in the 30–300 K temperature range and the nature of scintillation peaks reported on these samples is explained. Conclusions are drawn concerning the possibility to improve the scintillation yield of TeO2 crystals to be used as cryogenic bolometers operated at 10 mK in experiments studying the ββ decays of 130Te. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A thin‐film field‐emission cathode with Pt or Au interlayer between insulator and Zn0.75Mg0.25O
Authors: Wang Zengmei , Li Dejie
Published: March 2007

A thin‐film field‐emission cathode with Al/Ta2O5/(Pt or Au)/Zn0.75Mg0.25O/Pt–Au–Ag structure is proposed. Here, a Pt or Au interlayer is introduced between the insulator (Ta2O5) and semiconductor (Zn0.75Mg0.25O) layers in the metal‐insulator‐semiconductor‐metal (MISM) structure, in order to effectively control the interfacial electron‐energy‐state distribution. Consequently, the transmission current waveform of the proposed cathode becomes completely symmetric, while stable and uniform electron emission is reproducibly obtained. Maximum electron emission efficiency of 0.055% is obtained with a cathode using a Au interlayer and a Pt–Au–Ag top electrode. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Doping effect of Pr6O11 on superconductivity and flux pinning of MgB2 bulk
Authors: Pan X. F. , Shen T. M. , Li G. , Cheng C. H. , Zhao Y.
Published: March 2007

Bulk samples of MgB2 doped with 0, 1, 3, and 5 wt% Pr6O11 nanopowder were prepared using a solid‐state reaction route. The lattice constants of Pr6O11‐doped MgB2 systematically increase with increasing doping level, indicating a partial substitution of Pr for Mg in the crystal structure, and consequently, the superconducting transition temperature, Tc, of MgB2 is slightly suppressed. At a low doping level of 1 wt% Pr6O11, the critical current density, Jc, and the irreversibility field, Hirr are improved. However, at higher doping levels, Pr6O11 doping seems harmful for the performance of MgB2 in high magnetic fields. It is argued that the effect of the doping mechanism of Pr6O11 on Tc and Jc is quite different from those of other rare‐earth elements, such as Y or Dy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of K doping and annealing on the grain size and giant dielectric constant of KxTi0.02Ni0.98–xO ceramics
Authors: Kumar Jana Pradip , Sarkar Sudipta , Chaudhuri B. K.
Published: March 2007

Monovalent ion (MOI) doping effect on the grain size and giant dielectric constant (ϵ ′ ∼ 104) of lead free environment friendly NiO‐based Kx Ti0.02Ni0.98–x O (KTNO, x = 0.04, 0.25, and 0.30) type ceramics have been investigated. Increasing K concentration (MOI) enhances the grain size along with the increase of ϵ ′ values. The dielectric constant of KTNO also increases with increase of the sintering time and temperature (within the range of our measurement) due to enhancement of crystalline size. The giant ϵ ′ value and the leakage current in KTNO show weak field dependent behavior. Estimated temperature coefficient of permittivity (TCP) of KTNO is very low (less than 6%). All these properties meet the requirements of the ceramics used in X7R EIA specification. High ϵ ′ in KTNO is attributed to the boundary layer mechanism. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XRD measurement of thermal strain in InSb‐based devices
Authors: Declémy A. , Renault P. O.
Published: March 2007

The low temperature‐induced strain in the thin brittle InSb upper part of ready‐to‐work InSb‐based infrar‐ed photo‐detectors (Hybrid Focal Plane Arrays (HFPA) technology) has been measured using X‐ray diffraction (XRD). Assuming no shear component and no surface normal stress in the InSb upper part of the device and using linear elasticity laws lead to simple strain‐stress relations. It was shown that the maximum value of the thermal stress in the InSb part of the studied samples is well under the value of the yield stress of InSb at the working temperature of the devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
What is a watershed? Implications of student conceptions for environmental science education and the National Science Education Standards
Authors: Shepardson Daniel P. , Wee Bryan , Priddy Michelle , Schellenberger Lauren , Harbor Jon
Published: March 2007

The purpose of this study was to investigate students' conceptions about watersheds. Specifically: (1) What are students' conceptions of a watershed? and (2) In what ways might students' conceptions vary by grade level and community setting? This study was descriptive in nature and reflected a cross‐age design involving the collection of qualitative data from 915 students from the Midwest, United States. These qualitative data were analyzed for their content in an inductive manner, identifying student's conceptions. This content analysis was followed with a statistical analysis to determine the significance in the frequency of the identified student conceptions. Four categories emerged that reflected these students' conceptions. Based on these findings, we make curricular recommendations that build on the students' conceptions, the watershed concept, and the National Research Council (1996) Science Education Standards. © 2007 Wiley Periodicals, Inc. Sci Ed 91:554–578, 2007
Estimating the potential yield of small building‐mounted wind turbines
Authors: Heath Malcolm A. , Walshe John D. , Watson Simon J.
Published: March 2007

The wind profile in the urban boundary layer is described as following a logarithmic curve above the mean building height and an exponential curve below it. By considering the urban landscape to be an array of cubes, a method is described for calculating the surface roughness length and displacement height of this profile. Firstly, a computational fluid dynamics (CFD) model employing a k‐ϵ turbulence model is used to simulate the flow around a cube. The results of this simulation are compared with wind tunnel measurements in order to validate the code. Then, the CFD model is used to simulate the wind flow around a simple pitched‐roof building, using a semi‐logarithmic inflow profile. An array of similar pitched‐roof houses is modelled using CFD to determine the flow characteristics within an urban area. Mean wind speeds at potential turbine mounting points are studied, and optimum mounting points are identified for different prevailing wind directions. A methodology is proposed for estimating the energy yield of a building‐mounted turbine from simple information such as wind atlas wind speed and building density. The energy yield of a small turbine on a hypothetical house in west London is estimated. The energy yield is shown to be very low, particularly if the turbine is mounted below rooftop height. It should be stressed that the complexity of modelling such urban environments using such a computational model has limitations and results can only be considered approximate, but nonetheless, gives an indication of expected yields within the built environment. Copyright © 2007 John Wiley & Sons, Ltd.
Vaccines for Cholesterol Management
Authors: Rittershaus Charles W.
Published: March 2007

Over the last 50 years, several attempts have been made to harness the power and economy of vaccines in the fight against cardiovascular disease. Vaccines directed to lipoproteins, cholesterol itself, and molecules involved in cholesterol metabolism have all demonstrated success in modifying progression of disease in animal models of atherosclerosis. One vaccine that elicits antibodies to cholesteryl ester transfer protein has also progressed into the realm of human clinical testing. This review summarizes the published scientific work describing the various approaches that have been tried, their strengths and weaknesses, and where this field may go in the future.
Peak bone mass in patients with phenylketonuria
Authors: Modan‐Moses D. , Vered I. , Schwartz G. , Anikster Y. , Abraham S. , Segev R. , Efrati Ori
Published: March 2007

Objective: Several studies have suggested a compromised bone mass in phenylketonuria patients but most reported on heterogeneous or small patient groups. Our aim was to evaluate peak bone mass in adult PKU patients and to relate BMD to nutritional parameters. Patients and methods: BMD was measured by dual‐energy x‐ray absorptiometry in 31 adult PKU patients (18 female), mean age 25 ± 5.3 years. Nutritional intake was calculated based on food diaries. Diet adherence was determined based on patients’ report. Results: Mean blood phenylalanine (Phe) concentration was 968 ± 526 μmol/L (16 ± 8.7 mg/dl). Eight patients (32.2%) met the recommended blood Phe concentration of <726 μmol/L (<12 mg/dl), and there was no significant difference in Phe concentrations between diet‐adherent and non‐adherent patients. Osteopenia was detected in 11 patients (38.7%), while osteoporosis was detected in 2 patients (6.5%). No correlation was found between BMD and age, blood minerals, Phe, vitamin D and alkaline phosphatase levels, calcium and protein intake, body mass index, and body fat percentage. Conclusions: Peak bone mass is decreased in PKU patients. Possible explanations include long‐standing dietary deficiency in protein, calcium, vitamin D or trace elements, or a primary defect in bone turnover inherent to the disease itself. Our data do not favour any of these hypotheses. Further studies are needed to elucidate the cause of low bone density in PKU patients.
Molecular and clinical aspects of peroxisomal diseases
Authors: Shimozawa N.
Published: March 2007

Peroxisomal diseases, an expanding group of inborn errors of metabolism, can be classified into three categories—peroxisome biogenesis disorders (PBDs), single peroxisomal enzyme deficiencies, and contiguous gene syndrome. PBDs comprise 13 complementation groups and their responsible genes have been identified, including our newly identified group with a PEX14 defect. We have established a diagnostic system of peroxisomal diseases in Japan, and have identified 40 Japanese with PBDs, 11 patients with β‐oxidation enzyme deficiencies and more than 100 patients with adrenoleukodystrophy. Further study of and enlightenment on peroxisomal diseases is necessary to overcome these disorders.
Fabry disease: Baseline medical characteristics of a cohort of 1765 males and females in the Fabry Registry
Authors: Eng C. M. , Fletcher J. , Wilcox W. R. , Waldek S. , Scott C. R. , Sillence D. O. , Breunig F. , Charrow J. , Germain D. P. , Nicholls K. , Banikazemi M.
Published: March 2007

The Fabry Registry is a global observational research platform established to define outcome data on the natural and treated course of this rare disorder. Participating physicians submit structured longitudinal data to a centralized, confidential database. This report describes the baseline demographic and clinical characteristics of the first 1765 patients (54% males (16% aged < 20 years) and 46% females (13% < 20 years)) enrolled in the Fabry Registry. The median ages at symptom onset and diagnosis were 9 and 23 years (males) and 13 and 32 years (females), respectively, indicating diagnostic delays in both sexes. Frequent presenting symptoms in males included neurological pain (62%), skin signs (31%), gastroenterological symptoms (19%), renal signs (unspecified) (17%), and ophthalmological signs (11%). First symptoms in females included neurological pain (41%), gastroenterological symptoms (13%), ophthalmological (12%), and skin signs (12%). For those patients reporting renal progression, the median age at occurrence was 38 years for both sexes, but onset of cerebrovascular and cardiovascular events was later in females (median 43 and 47 years, respectively) than in males (38 and 41 years, respectively). This paper demonstrates that in spite of the considerable burden of disease in both sexes that begins to manifest in childhood or adolescence, the recognition of the underlying diagnosis is delayed by 14 years in males and 19 years in females. The Fabry Registry provides data that can increase awareness of common symptoms in all age groups, as well as insight into treated and untreated disease course, leading to improved recognition and earlier treatment, and possibly to improved outcomes for affected individuals.
Natives adapting to invasive species: ecology, genes, and the sustainability of conservation
Authors: Carroll Scott P.
Published: March 2007

Contemporary anthropogenic evolution is common. Biological invasions are an especially dynamic form of novel selection. This paper considers how native species evolve in response to biological invasions and the potential consequences of such evolution. Among numerous recent cases, the most widely reported instances are of phytophagous insects shifting onto introduced host plants. For example, our studies show that in North America and Australia, soapberry bugs evolved substantially after colonizing introduced hosts. Such cases permit close estimation of evolution's direction and rate, and we have used cross‐rearing studies of derived and ancestral‐type populations to measure changes in reaction norms and performance tradeoffs. Different fitness traits have followed very different paths in evolving to their current phenotypic values. Our hybridization studies show that the genetic architecture of these adaptations involves a surprising degree of non‐additive variation (epistasis, dominance). The importance of non‐additive genetic variation in rapid evolution will be clarified as more studies take advantage of similar situations. As appreciation grows for the deep contemporary interplay of evolution and ecology, debate about qualitative terms describing evolution's rate will become less relevant. From a conservation standpoint, contemporary evolution in native species presents challenges for ecologically appropriate and sustainable management. Evolving natives and invaders may reconfigure contemporary and future communities. Adaptive evolution may also enhance native communities’ capacity to control invasive populations.
Brief report: Perceptions of positive and negative support: Do they differ for pregnant/parenting adolescents and nonpregnant, nonparenting adolescents?☆
Authors: Crase Sedahlia Jasper , Hockaday Cathy , Cooper McCarville Pamela
Published: March 2007

This study was designed to examine perceptions of type, source, and amount of social support reported by pregnant and/or parenting (PP) and nonpregnant, nonparenting (NPNP) adolescents. Greater support generally was reported by NPNP than by PP adolescents. The groups did not differ with respect to their perceptions of types of support reported on either the Inventory of Socially Supportive Behaviors (ISSB) or the Arizona Social Support Interview Schedule (ASSIS). PP adolescents reported more support from teachers on the ASSIS than did NPNP adolescents. NPNP adolescents reported more support from best friends and sisters than did the PP group.