bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atomistic study of magnetism effect on structural stability in Fe3Al and Fe3AlX (X = H, B, C, N, O) alloys
Authors: Kellou A. , Grosdidier T. , Raulot J. M. , Aourag H. 
Published: February 2008

AbstractAtomistic modeling based on the density‐functional theory (DFT) within the generalized‐gradient approximation (GGA) is used to study the magnetic properties Fe3Al and Fe3AlX (X = H, B, C, N, O) compounds. The phase stability and the structural parameters are calculated for the selected iron‐aluminide alloys. The magnetic effects in Fe3AlX are shown and the predicted properties agree very well with the available experimental data. In the case of Fe3Al alloy, the DO3 structure is found to be more favorable than the L12 one. To the authors' knowledge, this is the first time that spin‐polarized GGA calculations have given the correct ground state of the Fe3Al alloys. In addition, the hypothetical phase of Fe3AlX′ (X′ = H, B, N, and O) structure is compared to the experimentally observed Fe3AlC structure. The unusual effect on magnetic properties of the C addition is shown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Negative compressibility, negative Poisson's ratio, and stability
Authors: Lakes Rod , Wojciechowski K. W. 
Published: February 2008

AbstractThe role of negative compressibility is considered in detail. Experimental observations of negative bulk modulus in pre‐strained foam are presented and interpreted. A constrained microscopic model which exhibits negative compressibility is proposed. Some other negative and counterintuitive properties of matter, like negative Poisson's ratio, negative thermal expansion, negative specific heat, and negative pressure are also discussed. A simple thermodynamic model with negative thermal expansion is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Isotopomeric characterization of N2O produced, consumed, and emitted by automobiles
Authors: Toyoda Sakae , Yamamoto Sei‐ichiro , Arai Shinji , Nara Hideki , Yoshida Naohiro , Kashiwakura Kiriko , Akiyama Ken‐ichi 
Published: February 2008

AbstractFossil fuel combustion is the second largest anthropogenic source of nitrous oxide (N2O) after agriculture. The estimated global N2O flux from combustion sources, as well as from other sources, still has a large uncertainty. Herein, we characterize automobile sources using N2O isotopomer ratios (nitrogen and oxygen isotope ratios and intramolecular site preference of 15N, SP) to assess their contributions to total global sources and to deconvolute complex production/consumption processes during combustion and subsequent catalytic treatments of exhaust. Car exhaust gases were sampled under running and idling state, and N2O isotopomer ratios were measured by mass spectrometry. The N2O directly emitted from an engine of a vehicle running at constant velocity had almost constant isotopomer ratios (δ15Nbulk = −28.7 ± 1.2‰, δ18O = 28.6 ± 3.3‰, and SP = 4.2 ± 0.8‰) irrespective of the velocity. After passing through catalytic converters, the isotopomer ratios showed an increase which varied with the temperature and the aging of the catalysts. The increase suggests that both production and consumption of N2O occur on the catalyst and that their rates can be comparable. It was noticed that in the idling state, the N2O emitted from a brand new car has higher isotopomer ratios than that from used cars, which indicate that technical improvements in catalytic converters can reduce the N2O from mobile combustion sources. On average, the isotopomeric signatures of N2O finally emitted from automobiles are not sensitive to running/idling states or to aging of the catalysts. Characteristic average isotopomer ratios of N2O from automobile sources are estimated at −4.9 ± 8.2‰, 43.5 ± 13.9‰, and 12.2 ± 9.1‰ for δ15Nbulk, δ18O, and SP, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
Liquid chromatography/mass spectrometric studies on atorvastatin and its stress degradation products
Authors: Shah Ravi P. , Kumar Vijay , Singh Saranjit 
Published: February 2008

AbstractA comprehensive mass fragmentation pathway of atorvastatin, which has not been reported so far, was established by subjecting the drug to multi‐stage mass spectrometric (MSn) studies. It was used along with liquid chromatography/mass spectrometric (LC/MS) and liquid chromatography/time‐of‐flight mass spectrometric (LC/TOFMS) analyses to identify the drug degradation products formed under stress conditions of hydrolysis, oxidation and photolysis. Other than lactone, which is a reported hydrolysis product, six unknown hydrolytic products could be identified, viz., dehydrated drug, dehydrated drug lactone, and diastereomers of the drug, drug lactone, dehydrated drug, and dehydrated drug lactone. Among the two products separated under oxidative conditions, one was lactone, again formed as a result of drug hydrolysis in an acidic environment of peroxide solution. The other was similar to a reported oxidative product. Under photolytic conditions in solution, one new product could be identified, while most of the others matched with those known from the literature. Hence overall a more complete degradation pathway of the drug was established than known at present, by using a stress testing approach and employing LC/MS techniques. Copyright © 2008 John Wiley & Sons, Ltd.
The stable hydrogen and oxygen isotope variation of water stored in polyethylene terephthalate (PET) bottles
Authors: Spangenberg Jorge E. , Vennemann Torsten W. 
Published: February 2008

AbstractA set of bottled waters from a single natural spring distributed worldwide in polyethylene terephthalate (PET) bottles has been used to examine the effects of storage in plastic polymer material on the isotopic composition (δ18O and δ2H values) of the water. All samples analyzed were subjected to the same packaging procedure but experienced different conditions of temperature and humidity during storage. Water sorption and the diffusive transfer of water and water vapor through the wall of the PET bottle may cause isotopic exchange between water within the bottle and water vapor in air near the PET‐water interface. Changes of about +4‰ for δ2H and +0.7‰ for δ18O have been measured for water after 253 days of storage within the PET bottle. The results of this study clearly indicate the need to use glass bottles for storing water samples for isotopic studies. It is imperative to transfer PET‐bottled natural waters to glass bottles for their use as calibration material or potential international working standards. Copyright © 2008 John Wiley & Sons, Ltd.
Unusual observations during steroid analysis
Authors: Kwok Wai Him , Leung David K. K. , Leung Gary N. W. , Tang Francis P. W. , Wan Terence S. M. , Wong Colton H. F. , Wong Jenny K. Y. 
Published: February 2008

AbstractIn September 2005, our laboratory detected the presence of 4‐androstene‐3,17‐dione and androsterone in a standard steroid screen of a post‐race gelding urine sample received from an overseas authority. All other urine samples from the same batch tested negative. Subsequent gas chromatography/mass spectrometry (GC/MS) confirmatory analyses, however, repeatedly failed to detect any amount of 4‐androstene‐3,17‐dione and androsterone in the suspicious sample. On the other hand, identical results were obtained when the initial GC/MS screening method was repeated on the suspicious sample as well as on the other samples of the same batch, showing the presence of 4‐androstene‐3,17‐dione and androsterone only in the suspicious sample. These unusual and contradictory findings between the screening and confirmatory procedures were investigated, leading to the unequivocal conclusion that the 4‐androstene‐3,17‐dione and androsterone observed during screening were artefacts from the internal standards, [16,16,17‐d3]‐testosterone and [16,16,17‐d3]‐5α‐androstane‐3α,17β‐diol. The two deuterated internal standards were thought to have undergone first an enzymatic oxidation of the 17β‐hydroxyl group to a 17‐keto function by the enzyme 17β‐hydroxysteroid dehydrogenase; complete deuterium‐hydrogen exchange at C16 during the methanolysis deconjugation step would then produce the two artefacts. The findings from this study highlight the potential problem of using internal standards in qualitative confirmatory analyses, which may lead to undesirable false positive results. Copyright © 2008 John Wiley & Sons, Ltd.
Robust stabilization for uncertain discrete singular systems with state delay
Authors: Wu Zhengguang , Su Hongye , Chu Jian 
Published: February 2008

AbstractThe robust stabilization problem for uncertain discrete singular time‐delay systems is addressed in this paper. In terms of strict linear matrix inequality and a finite sum inequality, a delay‐dependent criterion for the nominal systems to be admissible is obtained. Based on the criterion, a state feedback controller, which guarantees that, for all admissible uncertainties, the resulting closed‐loop system is regular, causal and stable, is constructed. An explicit expression for the desired controller is also given. The obtained results include both delay‐independent and delay‐dependent cases. Some numerical examples are introduced to show the effectiveness of the given results. Copyright © 2008 John Wiley & Sons, Ltd.
Biometric‐based user authentication in mobile ad hoc networks
Authors: Richard Yu F. , Tang Helen , Leung Victor C. M. , Liu Jie , Lung Chung‐Horng 
Published: February 2008

AbstractAs the front line of defense, user authentication is crucial for integrity and confidentiality. Mobile ad hoc networks (MANETs) impose a number of non‐trivial challenges to user authentication such as lack of central coordination and limited resources. In high security MANETs, continuous authentication is desirable so that a system can be monitored for the duration of the session to reduce the vulnerability. Biometrics provides some possible solutions to the authentication problem in MANETs, since it has direct connection with user identity. In this paper, we introduce some biometric technologies and their applications in the authentication problem. Multimodal biometrics can be used to exploit the benefits of one biometric while mitigating the inaccuracies of another. We propose an optimal multimodal biometric‐based continuous authentication scheme in MANETs. Some numerical results show the effectiveness of the proposed scheme. Copyright © 2007 John Wiley & Sons, Ltd.
Pore structure of activated carbon prepared from hazelnut bagasse by chemical activation
Authors: Demiral Hakan , Demiral İlknur , Tümsek Fatma , Karabacakoğlu Belgin 
Published: February 2008

AbstractIn this study, hazelnut extracted‐bagasse which is a waste from oil factory was used for the production of activated carbon by chemical activation using ZnCl2 and KOH as activating agents. Hazelnut bagasse has been impregnated with aqueous solutions of ZnCl2 and KOH in the ratio of 1–3 g agent per g precursor. The carbonization treatment was performed at 500, 600 and 700 °C for 2 h under nitrogen flow. The surface area, pore volumes, pore size distribution and average pore diameter of the activated carbons were characterized by N2 adsorption at 77 K using the BET, t‐plot and DFT methods. The highest surface areas of activated carbons are 1642 and 1489 m2/g and total pore volumes are 0.964 and 0.9329 cm3 g−1 for KOH and ZnCl2, respectively. The surface chemical characteristics of activated carbon were determined in terms of surface functional groups. These groups were analyzed by Fourier transform infrared (FTIR) spectroscopic method and Boehm's titration method. Surface morphology was investigated by SEM. According to the results, activated carbons prepared from hazelnut bagasse by chemical activation have high surface area and porosity. Copyright © 2008 John Wiley & Sons, Ltd.
Microstructure of the passive layer formed on AA2024‐T3 aluminum alloy surface implanted with nitrogen
Authors: Abreu C. M. , Cristóbal M. J. , Freitas P. , Nóvoa X. R. , Pena G. , Pérez M. C. , Serra C. 
Published: February 2008

AbstractThis work is focused on a detailed analysis of passive layer formed on AA2024‐T3 aluminum alloy, in unmodified and nitrogen‐implanted conditions. This study is the first step in analyzing the possible beneficial effect of nitrogen implantation in the simultaneous improvement of the tribological properties and pitting resistance. The implanted surface has been characterized by XPS and atomic force microscopy (AFM), and SEM/EDX has been used for microstructural characterization. XPS depth profile of the implanted surface shows the formation of AlN through the implanted layer. AFM studies have confirmed the increase of the surface roughness of AA2024‐T3 due to N+ implantation. Another interesting result of the present work is the detection by EDX analysis, of implanted alloy of a specific concentration of the implanted nitrogen in AlCuFeMnSi particles with regards to the other microstructural constituents. Copyright © 2008 John Wiley & Sons, Ltd.
Interfacial chemistry of epoxy adhesives on hydrated cement paste
Authors: Djouani Fatma , Connan Carole , Chehimi Mohamed M. , Benzarti Karim 
Published: February 2008

AbstractEpoxy resins [diglycidylether of bisphenol A, (DGEBA)] are the main adhesives used in civil engineering for the repair of damaged concrete structures (bridges, walls) or for assembly applications. Their interfacial molecular interactions with cement‐type substrates are thus of prime importance and require surface‐ and interface‐sensitive characterisation tools. In this context, we report an XPS, FTIR and differential scanning calorimeter (DSC) study of the interfacial chemistry of stoichiometric and nonstoichiometric epoxy mixtures [i.e. DGEBA resin and diethylenetriamine hardener (DETA)] coated on the surface of hardened‐cement pastes. XPS highlights the cross‐linking of the epoxy resin by the hardener and allows the detection of subtle mineral‐DETA hydrogen bonding. These specific interactions are confirmed by examination of the OH‐stretching frequency shifts in the FTIR spectra and concern essentially portlandite, one of the constitutive hydrates of cement paste. Additionally, it was found that interactions between the cross‐linked epoxy resin and the underlying‐mineral substrate induce an increase in the glass transition temperature (Tg) of the polymer adhesive from 48 to 66 °C. Copyright © 2008 John Wiley & Sons, Ltd.
Nonparametric sequential evaluation of diagnostic biomarkers
Authors: Liu Aiyi , Wu Chengqing , Schisterman Enrique F. 
Published: February 2008

AbstractWe consider evaluation and comparison of the diagnostic accuracy of biomarkers with continuous test outcomes, possibly correlated due to repeated measurements. We develop nonparametric group sequential testing procedures to evaluate and compare the area of biomarkers under their receiver operating characteristic curves, with either independent or paired test outcomes. These procedures rely on the construction of a two‐dimensional statistic of Whitehead (Statist. Med. 1999; 18:2271–2286) so that design methods based on Brownian motion can be applied. Copyright © 2008 John Wiley & Sons, Ltd.
Discovery of New Hexagonal Supramolecular Nanostructures Formed by Squalenoylation of an Anticancer Nucleoside Analogue
Authors: Couvreur Patrick , Reddy L. Harivardhan , Mangenot Stéphanie , Poupaert Jacques H. , Desmaële Didier , Lepêtre‐Mouelhi Sinda , Pili Barbara , Bourgaux Claudie , Amenitsch H. , Ollivon Michel 
Published: February 2008

AbstractIn this study, the dynamically folded conformation of squalene (SQ) is taken advantage of to link this natural compound to the anticancer nucleoside analogue gemcitabine (gem) in order to achieve the spontaneous formation of nanoassemblies (SQgem) in water. Cryogenic transmission electron microscopy examination reveals particles (104 nm) with a hexagonal or multifaceted shape that display an internal structure made of reticular planes, each particle being surrounded by an external shell. X‐ray diffraction evidences the hexagonal molecular packing of SQgem, resulting from the stacking of direct or inverse cylinders. The respective volumes of the gem and SQ molecules as well as molecular modeling of SQgem suggest the stacking of inverse hexagonal phases, in which the central aqueous core, consisting of water and gem molecules, is surrounded by SQ moieties. These SQgem nanoassemblies also exhibit impressively greater anticancer activity than gem against a solid subcutaneously grafted tumor, following intravenous administration. To our knowledge, this is the first demonstration of hexagonal phase organization with a SQ derivative.
Architecture framework human view: The NATO approach
Authors: Handley Holly A. H. , Smillie Robert J. 
Published: February 2008

AbstractThe NATO Research and Technology Organization (RTO) Panel on Human Factors and Medicine (HFM‐155) Human View Workshop was convened to discuss and propose a cross‐national Human View, that is, an architectural view that focuses on the human as part of a system. Progress on the idea of a human view had already been made by several different groups working in different countries. The purpose of the workshop panel was to evaluate these emerging human view concepts, propose a candidate human view construct, and develop an outline of a NATO‐wide Human View Handbook. This paper describes the outcomes of the workshop and presents the content of the draft human view suggested by the panel members. The proposed human view was purposely designed to be independent of any specific architecture framework and adaptable to different implementation processes. © 2008 Wiley Periodicals, Inc. Syst Eng 11
Effects of tobacco compounds on gene expression in fetal lung fibroblasts
Authors: Sohn Sung‐Hwa , Kim Ki‐Nam , Kim In kyoung , Lee Eun‐Il , Ryu Jae‐Jun , Kim Meyoung‐Kon 
Published: February 2008

AbstractThe goal of this study was to determine the effects of tobacco compounds on gene expression in a human fetal lung cell line (WI38). In the present study, we investigated the effects of tobacco compounds (nicotine, benzo(a)pyrene (B(a)P), and 2‐Naphthylamine) on gene expression profiles in human fetal fibroblasts using cDNA microarray and real‐time PCR. WI38 cells were cultured in Eagle's minimum essential medium (MEM) supplemented with 10% fetal bovine serum, 2% 200 mML‐glutamine, and a 2% penicillin and streptomycin solution. Tissue culture flasks (T‐25 cm2) containing confluent lung fibroblasts were incubated at 37°C for 24 h with 5 mL of medium supplemented with 10 μM of a tobacco compound (nicotine, B(a)P, or 2‐Naphthylamine). The gene expression profiles for the W138 cells varied depending on the tobacco compound. The cDNA microarray analysis revealed that apoptosis‐related genes such asDNASE2,MADD,MST1,NME3,RARG,TNFRSF1A,BAD, andDFFBgenes were down‐regulated in tobacco compound‐treated WI38 cells. We also observed significant increases inArntgene expression by real‐time PCR in tobacco compound‐treated WI38 cells. Tobacco compounds can affect apoptosis, immunity, and growth in WI38 cells. A microarray‐based genomic survey is a high‐throughput approach for the evaluation of gene expression in cell lines treated with tobacco compounds. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Comparing the relative toxicity of malathion and malaoxon in blue catfish Ictalurus furcatus
Authors: Aker Winfred G. , Hu Xiaoke , Wang Peng , Hwang Huey‐Min 
Published: February 2008

AbstractMalathion inhibits the critical body enzyme, acetylcholinesterase (AChE). This capability requires that malathion should first be converted to malaoxon to become an active anticholinesterase agent. Conversion can be caused by oxidation in mammals, insects, plants, and in sunlight. In this study, the effects of malathion and malaoxon on catfish Ictalurus furcatus were evaluated. After 96‐h exposures, the LC50 (concentration that causes 50% mortality) and IC50 (concentration that causes 50% enzyme inhibition) for malaoxon were lower than corresponding values for malathion. The overall mean 96‐h LC50 is 17.0 ppm for malathion and 3.1 ppm for malaoxon. IC50 values for malathion are 8.5 ppm for brain, 10.3 ppm for liver, and 16.6 ppm for muscle. Corresponding values for malaoxon are 2.3, 3.7, and 6.8 ppm, respectively. All the AChE activities in malathion‐ and malaoxon‐exposed catfish brain showed significant inhibition. The oxidation product malaoxon demonstrated higher inhibition on AChE activity than did malathion. Moreover, malaoxon showed significant inhibition on butyrylcholinesterase (BChE) in the liver if the concentrations were increased to more than 1 ppm. Malathion showed no difference between treatment group and control group. Compared with malathion, malaoxon showed higher inhibition on monoamine activity than that of malathion. The results indicated that the oxidative product malaoxon is more toxic than the parent compound malathion. AChE, BChE, and monoamine activities are confirmed as bioindicators of malathion exposure in blue catfish, I. furcatus. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Monitoring of DNA breakage in embryonic stages of the African catfish Clarias gariepinus (Burchell, 1822) after exposure to lead nitrate using alkaline comet assay
Authors: Osman Alaa G. M. , Mekkawy Imam A. , Verreth Johan , Wuertz Sven , Kloas Werner , Kirschbaum Frank 
Published: February 2008

AbstractIncreasing lead contamination in Egyptian ecosystems and high lead concentrations in food items have raised concern for human health and stimulated studies on monitoring ecotoxicological impact of lead‐caused genotoxicity. In this work, the alkaline comet assay was modified for monitoring DNA strand breakage in sensitive early life stages of the African catfish Clarias gariepinus. Following exposure to 100, 300, and 500 μg/L lead nitrate, DNA strand breakage was quantified in embryos at 30, 48, 96, 144, and 168 h post‐fertilization (PFS). For quantitative analysis, four commonly used parameters (tail % DNA, %TDNA; head % DNA, %HDNA; tail length, TL; tail moment, TM) were analyzed in 96 nuclei (in triplicates) at each sampling point. The parameter %TDNA revealed highest resolution and lowest variation. A strong correlation between lead concentration, time of exposure, and DNA strand breakage was observed. Here, genotoxicity detected by comet assay preceded the manifested malformations assessed with conventional histology. Qualitative evaluation was carried out using five categories are as follows: undamaged (%TDNA ≤ 10%), low damaged (10% < %TDNA ≤ 25%), median damaged (25 < %TDNA ≤ 50%), highly damaged (50 < %TDNA ≤ 75%), and extremely damaged (%TDNA > 75%) nuclei confirming a dose and time‐dependent shift towards increased frequencies of highly and extremely damaged nuclei. A protective capacity provided by a hardened chorion is a an interesting finding in this study as DNA damage in the prehatching stages 30 h‐PFS and 48 h‐PFS was low in all treatments (qualitative and quantitative analyses). These results clearly show that the comet assay is a sensitive tool for the detection of genotoxicity in vulnerable early life stages of the African catfish and is a method more sensitive than histological parameters for monitoring genotoxic effects. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.