bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential EI fragmentation pathways for peracetylated C‐glycoside ketones as a consequence of bicyclic ketal ring structures
Authors: Price Neil P. J. , Momany Frank A. , Adeuya Anthony 
Published: August 2007

AbstractSeveral C‐glycoside ketones and peracetylated C‐glycoside ketones have been synthesized from 13 structurally‐diverse aldoses sugars (including isotope labeled [1‐13C]Glc, [U‐13C]Glc, and [6, 6′‐2H2]Glc) via an aqueous‐based Knoevanagel condensation with aliphatic 1,3‐diketones. Sodium adduct molecular ions observed by MALDI‐TOF MS confirmed that the reactions are essentially quantitative, and that the acetylation products are the expected peracetylated C‐glycoside ketones, rather than cyclized ketofurans. Analysis of the peracetylated C‐glycoside ketones by gas chromatography‐EI‐MS show characteristic fragment ions that have been assigned to four distinct fragmentation pathways. Peracetylated aldohexose‐, aldopentose‐, and 6‐deoxyaldohexose‐C‐glycoside ketones fragment via gas phase furanoid intermediates. These data, and DFT calculations, indicate that the furanoid intermediates arise because the peracetylated C‐glycoside ketones adopt a bicyclic structure containing a 5‐member ketal ring. This ketal ring is the precursor of the furanoid rings in the gas phase. The 2‐deoxyhexose‐C‐glycoside ketones are unable to form an intramolecular 2‐ketal bond, and therefore undergo ion fragmentations via nonfuranoid pathways. Published in 2007 by John Wiley & Sons, Ltd.
The effects of weather and air pollution on cardiovascular and respiratory mortality in Santiago, Chile, during the winters of 1988–1996
Authors: Grass David , Cane Mark 
Published: August 2007

AbstractThis study quantifies the effects of stressful weather and elevated air pollution levels on cause‐specific mortality in Santiago, Chile, during the austral winters from 1988 to 1996. A temporal synoptic index (TSI) is used to form weather classes and air pollution classes. Prior applications of the TSI have formed classes solely on the basis of weather and may have systematically underestimated the impact of air pollution levels on daily mortality. In Santiago, the attribution of increased mortality risk was found to be largely dependent on the type of class formed (weather or pollution). High‐mortality weather classes were associated with cold, dry and high‐pressure conditions, while high‐mortality pollution classes were associated with elevated NO2 and PM10–2.5 concentrations. Cardiovascular disease mortality was more sensitive to weather conditions, and respiratory mortality was more sensitive to pollution levels. Respiratory mortality was most sensitive to stressful conditions at longer lag times (3–6 days), while cardiovascular mortality was most sensitive at shorter lag times (0–2 days). By understanding the relative magnitudes of health risks associated with stressful weather and air pollution conditions we can improve existing air pollution/weather watch systems and better anticipate future risks associated with global climate change. Copyright © 2007 Royal Meteorological Society
On ENSO impacts on European wintertime rainfalls and their modulation by the NAO and the Pacific multi‐decadal variability described through the PDO index
Authors: Zanchettin Davide , Franks Stewart W. , Traverso Pietro , Tomasino Mario 
Published: August 2007

AbstractWhile strong relationships have previously been established between the El Niño/Southern Oscillation (ENSO) and climate variability in many parts of the world, previous analyses of ENSO impacts on European rainfalls have been variable and inconclusive. In this paper, the role and apparent interactions of a range of known teleconnections are assessed. It is shown that ENSO events do indeed appear to impact European rainfalls and that these impacts are likely to also depend on the concurrent state of the North Atlantic Oscillation (NAO) and the Pacific Decadal Oscillation (PDO). In particular, it is demonstrated that ENSO impacts most significantly on European wintertime rainfalls during positive (warm) phases of the PDO. Copyright © 2007 Royal Meteorological Society
Genetic relationships based on discrete dental traits: Basketmaker II and Mimbres
Authors: LeBlanc S. A. , Turner C. G. , Morgan M. E. 
Published: August 2007

AbstractInvestigations of the relationships between culture and biology among prehistoric populations of the southwestern United States can enhance our reconstruction of social interactions. The present study analyses the permanent dentition of Basketmaker II and Mimbres individuals from multiple sites using the Arizona State University dental anthropology system, and compares them with a regional sample. Discrete dental trait analysis provides a useful means for assessing the degree of genetic relatedness between populations when large comparative samples are available. Both in situ cultural change and population replacement have been posited as the dominant mechanism acting on Basketmaker and early Puebloan groups. We examine the relationship of these populations to probable Uto‐Aztecan speakers in light of the Uto‐Aztecan farmer migration hypothesis. The Basketmaker II complex, traditionally recognised as a distinct cultural unit, exhibits considerable population heterogeneity. Western Basketmakers appear to share biological ties with Uto‐Aztecan speakers, while Eastern Basketmakers do not, as predicted by the model. The relationship of the Mimbres to probable Uto‐Aztecan speakers is less clear because the Mimbres show only weak affinities to northern Mexican populations. Copyright © 2007 John Wiley & Sons, Ltd.
Advanced nucleating agents for polypropylene
Authors: Libster Dima , Aserin Abraham , Garti Nissim 
Published: August 2007

AbstractThe present short review aims to summarize advanced nucleating agents for polypropylene (PP). Reviewing the relevant literature, we focused on powerful nucleators that are capable of significantly increasing the crystallization temperature of the polymer at very low working concentrations and also serving as clarifying agents. The nucleation mechanism and efficiency of these compounds are discussed in detail. The nucleating agents were divided into groups according to their tendency to induce monoclinic (α), hexagonal (β), or orthorhombic (γ) PP cell geometries. The major α‐nucleators and clarifiers are sorbitol‐based compounds that speed‐up the polymer crystallization due to gelation phenomena and induction of epitaxial crystallization by the metal salts of substituted aromatic heterocyclic phosphate. Among β‐nucleators, N,N′‐dicyclohexyl‐2,6‐naphthalene dicarboxamide was found to be very efficient and its nucleation ability was highly concentration dependent. In addition, it was shown that nucleation efficiency of a nucleator can be significantly increased by a new dispersion method comprising its solubilization in a microemulsion. Moreover, the nucleator (HPN‐68) increased the γ‐modification present in the polymer. Copyright © 2007 John Wiley & Sons, Ltd.
Risk of recurrence in major central nervous system malformations between 1976 and 2005
Authors: Joó József Gábor , Beke Artúr , Papp Zoltán , Csaba Ákos , Rab Attila , Papp Csaba 
Published: August 2007

AbstractObjectiveThe goal of the current publication is to review isolated central nervous system malformations (CSMs) using a database in excess of 75 000 cases, with special regard to the risk of recurrence of these malformations alone or in combination.MethodsIn the period between 1 January 1976 and 31 December 2005, among the 75 320 documented cases, consultations were requested due to earlier isolated CSMs in the patients' histories in 3030 cases (4.2%). Processing the data we only considered disorders of genetic origin, and that was why we excluded the cases due to intrauterine infection. Monogenically inherited malformations were also excluded from the analysis. The diagnosis of the malformations was based on the prenatal diagnosis of ultrasonography as well as the findings of the foetopathological examination.ResultsIn 65% of the cases, the couples sought counselling because of malformation in a previous pregnancy. In these cases, the risk of recurrence was thought to be 5.2%, while in the case of two affected children this figure stood at 21.9%. Analysing the values for the risk of recurrence in 5‐year periods, neural tube defects (NTDs) (particularly anencephaly and spina bifida) showed a detectable decrease, which could be attributed to a growing use of folic acid supplementation around the time of conception and during pregnancy.ConclusionThere is a clear decrease of risk of recurrence of NTDs, while in the case of the other CSMs in this study, there is no noteworthy chronological change in their risk of recurrence. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis of ω‐functionalized poly(1,3‐cyclohexadiene): addition of fluorescent functional group to the polymer chain end
Authors: Natori Itaru , Sato Hisaya , Natori Shizue 
Published: August 2007

AbstractBACKGROUND: Poly(1,3‐cyclohexadiene) (PCHD) is of interest as a precursor for the synthesis of a new class of high‐performance hydrocarbon polymers. ω‐Functionalization of PCHD offers a new opportunity for the preparation of a variety of multifunctional PCHD derivatives.RESULTS: ω‐Functionalized PCHD containing a fluorenyl (or anthracenyl) group at the polymer chain end was successfully synthesized by post‐polymerization reaction of poly(1,3‐cyclohexadienyl)lithium (PCHDLi) with alkyl halides containing a fluorescent functional group. The degree of nucleophilicity of PCHDLi and the control of side reactions were very important factors to achieve a high conversion for the post‐polymerization reactions of PCHDLi. The ω‐functionalized PCHDs obtained exhibited strong photoluminescence and the wavelength of the fluorescence was adjustable by changing the structure of the ω‐functional group.CONCLUSION: ω‐Functionalized PCHD is a preferable precursor that can be utilized to obtain a new class of multifunctional hydrocarbon polymers containing six‐membered rings in the main chain. Copyright © 2007 Society of Chemical Industry
Methoxy poly(ethylene glycol)‐block‐poly(D,L‐lactic acid) copolymer nanoparticles as carriers for transdermal drug delivery
Authors: Li Jun , Zhai Yinglei , Zhang Bin , Deng Liandong , Xu Yongshen , Dong Anjie 
Published: August 2007

AbstractThis work evaluates the transdermal drug delivery properties of amphiphilic copolymer self‐assembled nanoparticles by skin penetration experiments in vitro. Paclitaxel‐loaded methoxy poly(ethylene glycol)‐block‐poly(D,L‐lactic acid) diblock copolymer nanoparticles (PNPs) were prepared by a solid dispersion technique and were applied to the surface of excised full‐thickness rat skin in Franz diffusion cells. HPLC, transmission electron microscopy, Fourier transform infrared spectroscopy and 1H NMR were used to assay the receptor fluid. The results show that the amphiphilic copolymer nanoparticles with the entrapped paclitaxel are able to penetrate rat skin. Ethanol can improve the delivery of PNPs and increase the cumulative amount of paclitaxel in the receptor fluid by 3 times. Fluorescence microscopy measurements indicate that the PNPs can penetrate the skin not only via appendage routes including sweat ducts and hair follicles but also via epidermal routes. Copyright © 2007 Society of Chemical Industry
New organic semiconductor materials: electrical conductivity, thermal properties and application of voltage‐controlled negative resistance device of poly[(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐co‐(maleic acid)]
Authors: Yakuphanoglu Fahrettin , Soykan Cengiz , Coşkun Ramazan 
Published: August 2007

AbstractBACKGROUND: Electrical conductivity, photoconductivity, voltage‐controlled negative resistance and thermal properties of copolymers of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid and maleic acid were investigated in order to obtain new organic semiconductors.RESULTS: The room temperature conductivity of three different copolymers was found to be in the range 1.28 × 10−8 − 1.20 × 10−7 S cm−1. The dark‐ and photo‐current‐voltage characteristics indicate that the copolymers exhibit voltage‐controlled differential negative resistance behaviour. The electrical conductivity of the polymers increases by photo‐illumination, suggesting that the polymers exhibit photoconductivity. The width of the exponential tail in the forbidden band gap of the three polymers was determined via the transient photocurrent technique and E0 values were in the range 34.4–36.49 meV.CONCLUSION: The results suggest that the copolymers could be used as organic semiconductor materials. Copyright © 2007 Society of Chemical Industry
Development of a robust hydrogel system based on agar and sodium alginate blend
Authors: Meena Ramavatar , Chhatbar Mahesh , Prasad Kamalesh , Siddhanta Arup K 
Published: August 2007

AbstractBACKGROUND: As part of an ongoing research and development programme of our laboratory on functional modification of seaweed polysaccharides for preparing hydrogels with improved properties, we report herein the preparation of a robust hydrogel system based on grafting of agar and sodium alginate blend (Agar/Na‐Alg) with acrylamide (AAm) to obtain the copolymer Agar/Na‐Alg‐graft‐PAAm.RESULTS: A robust hydrogel system with superior absorbency and pH resistance has been developed based on a PAAm‐grafted seaweed polysaccharide blend of Agar/Na‐Alg. The blend (Agar/Na‐Alg) and grafted product (Agar/Na‐Alg‐graft‐PAAm) were evaluated using Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, swelling capacity, rheology and scanning electron microscopy. The swelling capacity of the grafted copolymer exhibited an enhancement over that of the blend from 14 to 24 g g−1 in acidic medium. The blend and grafted copolymer produced hydrogels with lower gelling points of 31 and 29 °C and gel strengths were 170 and 120 g cm−2, respectively.CONCLUSION: This study constitutes an example of value addition of seaweed polysaccharides targeting new applications. The copolymer hydrogel may be useful in health, personal care and agricultural applications. Copyright © 2007 Society of Chemical Industry
Spot arrays on modified glass surfaces for efficient SPOT synthesis and on‐chip bioassay of peptides
Authors: Kim Do‐Hyun , Shin Dong‐Sik , Lee Yoon‐Sik 
Published: August 2007

AbstractTo make SPOT synthesis of peptides and their assays on glass surfaces more convenient, a simple method for making spot arrays on a slide glass was designed through patterning with a photoresist and perfluorination followed by amination with various silane compounds and polymers. With these spot‐arrayed glass surfaces, we could measure the coupling completion of each Fmoc amino acid on the glass surface by direct fluorescence analysis after fluorescence‐labeling the amino groups on the surface of each spot. Then we synthesized several types of decapeptides and HPQ‐pentapeptides on the spot‐arrayed glasses and identified the optimal surface condition for stepwise peptide coupling and on‐chip bioassay. After optimizing the surface conditions, we synthesized a model library of biotin‐Gly‐Ala‐P1‐Gly (P1: one of 19 amino acids) and successfully replicated the well‐known α‐chymotrypsin subsite specificities through Cy5‐streptavidin binding to the remaining biotin on the surface after the enzymatic digestion. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Applicability of the MCNPX particle transport code for determination of the source correction effect in positron lifetime measurements on thin polymer films
Authors: Urban‐Klaehn J. M. , Spaulding R. , Hunt A. W. , Peterson E. S. 
Published: August 2007

AbstractThe method presented herein uses the MCNPX Monte Carlo particle transport code to track individual positrons and other particles through geometry that accounts for the detectors, backing foils, samples and sources with their actual sizes, positions and material characteristics. Polymer material, polydimethylsiloxane (PDMS), with different thickness of films served as samples. The excellent agreement between the experimental results and the MCNPX simulation of source correction effects for varied positron sources and different film thicknesses validates the applicability of the MCNPX code. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of ion beam‐induced SiC‐OI structures by positron annihilation spectroscopy
Authors: Maekawa M. , Yu R. S. , Kawasuso A. 
Published: August 2007

AbstractEffect of oxygen ion implantation to SiC at 600 °C has been studied by positron annihilation spectroscopy using energy‐variable slow positron beams. The Doppler broadening of annihilation radiation and positron lifetime measurements showed that vacancy defects survive and no SiO2 layer is formed in the as‐implanted state. Following post‐implantation annealing at 1400 °C, vacancy clusters were removed. Furthermore, a SiO2‐like layer is formed in the oxygen‐implanted region. An interface layer, which resembles that of the SiO2/SiC produced by conventional oxidation, was also found. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High moderation efficiency positron beamline
Authors: Wu Y. C. , Chen Y. Q. , Wu S. L. , Chen Z. Q. , Wang S. J. , Greaves R. G. 
Published: August 2007

AbstractA new positron beam system, which has high moderation efficiency and can measure positron lifetime spectra, has been constructed at Wuhan university. A solid neon moderator with about 1% moderation effeciency is used. Secondary electron time‐tagging can be used to measure the positron annihilation lifetime. A target chamber has been designed for positron annihilation lifetime spectroscopy (PALS), Doppler broadening (DB) and coincidence Doppler broadening (CDB). The preliminary beam parameters are: a slow positron flux of 5 million per second for 40 mCi 22Na radioactive isotope, a positron energy spread as narrow as 2.0eV, and a moderator decay rate of 4% per day. Variable energy Doppler broadening annihilation radiation data for stainless steel samples are shown, which demonstrate the capabilities of the system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrogen‐damaged defects near the surface in heavily deformed iron and steels investigated by slow positron annihilation spectroscopy
Authors: Wu Y. C. , Jean Y. C. 
Published: August 2007

AbstractHydrogen‐damaged defects of heavily deformed iron, AISI 304‐, and 316‐stainless steels were investigated by measuring Doppler broadening energy spectra (DBES) of positron annihilation radiation. It is interestingly found that S‐parameter as a function of energy on three kinds of deformed samples falls into the similar variation, independent of chemical elements and impurities. A larger S value near the surface in deformed and hydrogen‐damaged samples than in samples without hydrogen‐damaged samples is because of the additional larger‐sized defects (e.g. voids) induced due to hydrogen damage. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron lifetime study on the degradation of LaNi5 and LaNi4.8Sn0.2 during hydrogen absorption‐desorption cycling
Authors: Araki Hideki , Date Ryousuke , Sakaki Kouji , Mizuno Masataka , Shirai Yasuharu 
Published: August 2007

AbstractLaNi5 and LaNi4.8Sn0.2 alloys have been subjected to pressure‐induced cycling tests at 248 K under a hydriding condition at a hydrogen pressure of 3 MPa and under a dehydriding condition of evacuating by a rotary pump. At the beginning of cycling the hydrogen absorbing capacity of LaNi5 was larger than that of LaNi4.8Sn0.2. However, the capacity of LaNi5 was markedly decreased by the cycling, whereas the capacity of LaNi4.8Sn0.2 was hardly changed. After 100 cycles, the capacity of LaNi5 became smaller than that of LaNi4.8Sn0.2. On the other hand, it was also found that the increase in the positron mean lifetime by the cycling for LaNi4.8Sn0.2 was smaller than that for LaNi5, revealing that substitution of Sn suppresses the formation of vacancy during the cycling. This result suggests that the degradation in hydrogen absorbing capacity should be attributed at least partly to trapping of hydrogen at excess vacancy formed by hydriding. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the precipitation sequence in a Ni‐based superalloy: A Coincidence Doppler Broadening study
Authors: Macchi C. E. , Somoza A. , Santos G. , Petkov M. , Lynn K. G. 
Published: August 2007

AbstractThe precipitation sequence at 700 °C of the Ni3(Ti,Al)‐type ordered γ' phase in the commercial nickel‐based superalloy Inconel X‐750 was investigated using Coincidence Doppler Broadening (CDB) technique. The results obtained are discussed in terms of positron annihilation in two well‐defined states: one corresponding to the matrix (γ phase) and a second related to the γ' precipitates. Between these two aging stages, CDB distributions corresponding to selected intermediate aging treatments could be presented exactly, within the experimental scatter, as a linear combination of the γ and γ' signatures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron diffusion in the liquid metal phase
Authors: Matsushita Y. , Kitahata H. , Kanazawa I. 
Published: August 2007

AbstractWe have analyzed the positron diffusion length date in the liquid phase of In metal from the view point of the restoration of the spontaneously broken density around the positron. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of defects and phase transformation in a Fe‐Mn‐Si‐Cr‐Ni alloy by positron annihilation method
Authors: Mostafa Khaled M. , Van Caenegem N. , De Baerdemaeker J. , Segers D. , Houbaert Y. 
Published: August 2007

AbstractDefects in Fe‐Mn‐Si‐Cr‐Ni samples were studied at room temperature. Steel samples were deformed during a tensile experiment up to a strain of 17%. The evolution of the defect structure was followed by Doppler broadening measurements. Before and after the deformation the samples were also characterised by positron lifetime measurements. Light optical microscopy (OM) gave information about the different microstructural phases that exist in the deformed and the undeformed alloys. During deformation a martensitic ε phase is induced. The size of the martensite plates increases with increasing deformation. The S‐W plot during the deformation is not linear. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atomic structure and positron lifetime in the metallic glass Zr55Cu30Ni5Al10
Authors: Sugita K. , Matsumoto M. , Mizuno M. , Araki H. , Shirai Y. 
Published: August 2007

AbstractZr‐based metallic glasses have superior characteristics such as mechanical strength, corrosion resistance and precision casting ability. From positron lifetime measurements, a negative temperature dependence of the mean positron lifetime above room temperature was reported and ascribed to the presence of shallow traps. However, the trapping sites remain unknown under the present circumstances. To get a further understanding of the experimental positron lifetime value, the positron density distribution and the lifetime in the Zr‐based metallic glass Zr55Cu30Ni5Al10 have been calculated. The calculation shows that the positrons are annihilated inhomogeneously and most positrons are annihilated preferentially around Cu/Al. These results indicate that the positron lifetime not exactly reflects the total free volume. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)