bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of plates stiffened by parallel beams
Authors: Sapountzakis E. J. , Mokos V. G.
Published: November 2006

In this paper a general solution for the analysis of plates stiffened by parallel beams subjected to an arbitrary loading is presented. According to the proposed model, the stiffening beams are isolated from the plate by sections in the lower outer surface of the plate, taking into account the arising tractions in all directions at the fictitious interfaces. The aforementioned integrated tractions result in the loading of the beams as well as the additional loading of the plate. Their distribution is established by applying continuity conditions in all directions at the interfaces. The analysis of both the plate and the beams is accomplished on their deformed shape taking into account second‐order effects. Six boundary value problems with respect to the plate transverse deflection, to the plate inplane displacement components, to the beam transverse deflections, to the beam axial deformation and to the beam non‐uniform angle of twist are formulated and solved using the analog equation method (AEM), a boundary element method (BEM)‐based method employing a boundary integral equation approach. The solution of the aforementioned plate and beam problems, which are non‐linearly coupled, is achieved using iterative numerical methods. The adopted model describes better the actual response of the plate beams system and permits the evaluation of the shear forces at the interfaces in both directions, the knowledge of which is very important in the design of prefabricated ribbed plates. The evaluated lateral deflections of the plate–beams system are found to exhibit considerable discrepancy from those of other models, which neglect inplane and axial forces and deformations. Copyright © 2006 John Wiley & Sons, Ltd.
Estimation of cable safety factors of suspension bridges using artificial neural network‐based inverse reliability method
Authors: Cheng Jin , Cai C. S. , Xiao Ru‐Cheng
Published: November 2006

The design of the main cables of suspension bridges is based on the verification of the rules defined by standard specifications, where cable safety factors are introduced to ensure safety. However, the current bridge design standards have been developed to ensure structural safety by defining a target reliability index. In other words, the structural reliability level is specified as a target to be satisfied by the designer. Thus, calibration of cable safety factors is needed to guarantee the specified reliability of main cables. This study proposes an efficient and accurate algorithm to solve the calibration problem of cable safety factors of suspension bridges. Uncertainties of the structure and load parameters are incorporated in the calculation model. The proposed algorithm integrates the concepts of the inverse reliability method, non‐linear finite element method, and artificial neural networks method. The accuracy and efficiency of this method with reference to an example long‐span suspension bridge are studied and numerical results have validated its superiority over the conventional deterministic method or inverse reliability method with Gimsing's simplified approach. Finally, some important parameters in the proposed method are also discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Nano clay reinforced biodegradable plastics of PCL starch blends
Authors: Ikeo Yasuhiro , Aoki Kazuhiko , Kishi Hajime , Matsuda Satoshi , Murakami Atsushi
Published: November 2006

One of the conventional methods to develop biodegradable plastics at a reasonable cost is manufacturing the blend of expensive polycaprolactone (PCL) and lower‐priced starch. However, past studies have shown that the amount of starch blended with plastics is relatively small and the dynamic properties are not sufficiently improved. This study focuses on the improvement of physical properties of starch, including thermal plasticity, compatibility with PCL and dynamic properties. Starch was blended with glycerine and water to achieve thermal plasticity and improve compatibility with PCL. Addition of maleic anhydride to PCL improved compatibility, which resulted in improved dynamic properties. Addition of clay results in dispersed thermo plastic starch, which improves compatibility with PCL. In addition, it was clarified that addition of clay accelerates the positive effect of electron irradiation on the blend. Copyright © 2006 John Wiley & Sons, Ltd.
Pinch‐off syndrome in patients with sickle cell disease receiving erythrocytapheresis
Authors: Nuss Rachelle , Cole Laura , Le Tuan , Orsini Edmund , Harned Roger
Published: November 2006

A 6‐year‐old female with homozygous sickle cell disease had a central venous access device (CVAD) placed to facilitate chronic erythrocytapheresis. Erythrocytapheresis was ineffective due to the rare pinch‐off syndrome causing communication between the dual lumen tubing. Awareness of and monitoring for the pinch‐off syndrome is indicated in people with sickle cell disease and a CVAD for chronic erythrocytapheresis. Pediatr Blood Cancer 2008;50:354–356. © 2006 Wiley‐Liss, Inc.
SRPK1: A cisplatin sensitive protein expressed in retinoblastoma
Authors: Krishnakumar Subramanian , Mohan Adithi , Kandalam Mallikarjuna , Ramkumar Hema L. , Venkatesan Nalini , Das Radha R.
Published: November 2006

Chemotherapy is an essential modality in the treatment of retinoblastoma (RB). Mammalian serine/arginine‐rich protein‐specific kinase 1 (SRPK1) is a cisplatin‐sensitivity‐related protein and its downregulation is known to be associated with decreased response to cisplatin and carboplatin. We investigated the expression of SRPK1 in 63 archival RB and correlated its expression with pathologic staging and exposure to chemotherapy. The majority of the RB (62/63) were advanced stage (Groups D and E) with intermediate to high risk of treatment failure according to the new international classification for intraocular RB and SRPK1 was reduced in 32/62 (51%) tumors. SRPK1 protein expression was reduced in (100%) 8/8 RB that had recurred in the orbit or had metastasized. SRPK1 protein expression is reduced in RB with advanced stage of presentation and this may add to drug resistance mechanisms in RB. Pediatr Blood Cancer 2008;50:402–406. © 2006 Wiley‐Liss, Inc.
Benzophenone‐functionalized, starlike polystyrenes as organic supports for a tridentate bis(imino)pyridinyliron/trimethylaluminum catalytic system for ethylene polymerization
Authors: Bouilhac Cécile , Cramail Henri , Cloutet Eric , Deffieux Alain , Taton Daniel
Published: November 2006

Starlike polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4‐(1‐bromoethyl)‐benzophenone, with divinylbenzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and had to be removed. This was readily achieved with Cu0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6‐bis[1‐2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine‐free, functionalized polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6997–7007, 2006
Ellipsometry as a probe of crystallization kinetics in thin diblock copolymer films
Authors: Carvalho J. L. , Massa M. V. , Dalnoki‐Veress K.
Published: November 2006

We present results on the use of ellipsometry as a novel probe for the crystallization kinetics in thin films of a diblock copolymer. Ellipsometry makes use of the change in polarization induced upon the reflection of light from a film‐covered substrate to enable the calculation of the refractive index and thickness of the film. The information obtained with these measurements can be compared with information from differential scanning calorimetry, with the additional advantages that small sample volumes and slow cooling rates can be employed and that expansion coefficients can be determined. By studying the temperature dependence of these quantities, we are able to measure the crystallization kinetics within very small volumes (∼10−10 L) of a poly(butadiene‐b‐ethylene oxide) diblock copolymer. Through a comparison of two different poly (ethylene oxide) block lengths, we demonstrate a reduction in both the crystallization and melting temperatures as the domain volume is reduced. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3448–3452, 2006
Exfoliation of stacked sheets: Effects of temperature, platelet size, and quality of solvent by a Monte Carlo simulation
Authors: Pandey R. B. , Anderson K. L. , Farmer B. L.
Published: November 2006

Can a layer of stacked sheets (coarse grained description of clay platelets) exfoliate in a given solvent? Computer simulations are performed to address this question with a stacked layer of four sheets. A sheet is described by a set of nodes (N) tethered together by flexible (fluctuating) bonds in a planar structure with linear scaleLs,N=Ls2on a cubic lattice of sizeL3. The initial distance between the sheets is small and kept constant for different sets of stacked sheets. Quality of the effective solvent is controlled by a short range interaction (ε) between sheets, that is, their nodes and the empty lattice sites (ε = −2,−1, 1, 2). Nodes execute stochastic movement with the Metropolis algorithm subject to bond fluctuation and excluded volume constraints. Simulations are also performed at different temperatures. Visual analysis shows that the exfoliation depends on the size of the sheet and temperature. We find that it is easier to exfoliate smaller sheets and that the exfoliation is enhanced by raising the temperature. The exfoliation becomes very slow for large sheets at low temperatures because of longer relaxation times. Exfoliation is enhanced by increasing the attractiveness (i.e., the quality) of the solvent interaction with the platelets. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3580–3589, 2006
Ferroelastic to paraelastic phase transition of K3H(SeO4)2 and Rb3H(SeO4)2 single crystals studied by nuclear magnetic resonance and external stress
Authors: Lim Ae Ran , Ham Shin Gyoon , Chang Jin‐Hae , Ichikawa M.
Published: November 2006

The temperature dependences of the nuclear magnetic resonance (NMR) and the stress–strain hysteresis curves have been measured for K3H(SeO4)2 and Rb3H(SeO4)2 crystals grown using the slow evaporation method. By analysis of the 39K and 87Rb NMR results, it has been confirmed that the phase below TC is ferroelastic with twin domains and that the phase above TC is paraelastic with a single domain. The ferroelastic domain switching that occurs in the two single crystals due to external stress was also studied. The critical stress values for converting the twin‐domain state to the single‐domain state were obtained. When external stresses of 0.6 and 0.4 MPa were applied to the K3H(SeO4)2 and Rb3H(SeO4)2 crystals, respectively, transitions from twin‐domain to single‐domain states were observed. The ferroelastic domain switching resulting from an external stress may be associated with the atomic rearrangements of the SeO4 tetrahedra in K3H(SeO4)2 and Rb3H(SeO4)2 crystals; the ferroelastic domain switching is explained by the restriction of the rotation of the SeO4 tetrahedra as a result of the breaking of all hydrogen bonds by the external stress. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties of lead nitrate single crystals
Authors: Isoda Hiroshi , Kawashima Riki
Published: November 2006

The measured alternating current (ac) electrical conductivity of lead nitrate [Pb(NO3)2] crystals in the frequency range 20–106 Hz at temperature varying from 200 to 320 K shows anomalous temperature dependence, having meta‐stability in the temperature range from 240 to 300 K. The dynamic properties have been extracted from these ac electrical data. The frequency exponents derived from the power law of the conductivity exhibit a singularity in this temperature variation range. A critical slowing down has been observed at temperatures near 275 K. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and electrical properties of Sr‐modified Pb(NbMo)3 system
Authors: Rai Radheshyam , Bihari Bipin , Singh N. K. , Choudhary R. N. P.
Published: November 2006

Strontium (Sr)‐doped (Pb1–z Srz )0.375(Nb0.75Mo0.25)O3 (PSNM), where z = 0.00, 0.03, 0.05, 0.07, has been synthesized by a solid‐solution mixing technique. Some aspects of structure of the compound at room temperature were studied using an X‐ray diffraction (XRD) technique. Dielectric studies (dielectric constant (ϵ) and dielectric loss (tan δ)) obtained both as a function of frequency (100 Hz to 100 kHz) at room temperature (RT) and temperature (RT – 500 K) at 10 kHz suggest that compounds undergo a ferroelectric–paraelectric phase transition of the diffuse type. The activation energy (Ea) of the samples was calculated from the plot of ac conductivity versus the inverse of absolute temperature. The activation energy (Ea) of all the doped compounds was found to be very low. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tunneling spectroscopy of quantum wires: Spin‐charge separation and localization
Authors: Yacoby A. , Auslaender O. M. , Steinberg H. , Tserkovnyak Y. , Halperin B. I. , Baldwin K. W. , Pfeiffer L. N. , West K. W.
Published: November 2006

Using a double wire geometry we probe the quantum many‐body modes in ballistic wires and their dependence on Coulomb interactions. The wires are fabricated using the cleaved edge overgrowth method. We clearly observe two spin modes and one charge mode of the coupled wires. We map the dispersion velocities of the modes down to a critical density at which spontaneous localization is observed. Theoretical calculations of the charge velocity agree well with the data, although they also predict an additional charge mode that is not observed. Surprisingly, the suppression of the spin velocities does not depend on density. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum shot noise in edge channels
Authors: Heiblum M.
Published: November 2006

Charge excitations under quantized magnetic field flow in one dimensional‐like strips along the edges of the sample. These excitations (quasiparticles) may behave independently (under weaker fields) or condense to an interacting chiral Luttinger liquid (under stronger fields). Adding a backscattering potential in the path of the quasiparticles, partitions them, hence inducing quantum shot noise that is proportional to their charge and is affected by their correlation. We summarize here our studies of the noise in edge states. At sufficiently low temperatures the correlations among the scattering events are strong, leading to highly non‐linear I –V characteristic and non‐classical shot noise. However, at finite temperatures and weak back scattering, quasiparticles backscatter independently, with noise proportional to e /3, e /5 and e /7 at filling factors 1/3, 2/5, and 3/7. Alternatively, at sufficiently strong backscattering induced bunching of e /3 quasiparticles takes place, with shot noise proportional to e. Diluting the impinging quasiparticles beam mimics an increased temperature, effectively weakening the correlation, rendering the quasiparticles scattering stochastic. Moreover, surprisingly, at finite temperatures (∼50 mK), highly dilute fractionally charged quasiparticle beams are found to traverse almost opaque barriers with no significant bunching. Bunching, however, takes place at lower temperatures. In the opposite case of very weak backscattering potential and at extremely low temperatures (∼9 mK), surprising bunching of quasiparticles takes place: e * = 2e /5 at filling factor 2/5 and e * close to 3e /7 at filling factor 3/7. Under the same conditions, as the temperature increases, (to 25–50 mK) bunching ceases and the scattered charge is again the familiar Laughlin's quasiparticles charge e/m. We show also the shot noise generated by an edge channel interferometer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin ordering: two different scenarios for the single and double layer structures in the fractional and integer quantum Hall effect regimes
Authors: Dolgopolov V. T. , Deviatov E. V. , Khrapai V. S. , Reuter D. , Wieck A. D. , Wixforth A. , Campman K. L. , Gossard A. C.
Published: November 2006

We investigate the ground state competition at the transition from the spin unpolarized to spin ordered phase at filling factor ν =2/3 in single layer heterostructure and at ν =2 in double layer quantum well. To trace the quantum Hall phase we use the minimum in the dissipative conductivity σ xx We observe two different transition scenarios in two investigated situations. For one of them we propose a qualitative explanation, based on the domain structure evolution in the vicinity of the transition point. The origin for the second scenario, corresponding to the experimental situation at ν =2 in double layer quantum well, still remains unclear. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wannier–Stark level anticrossing in biperiodic superlattices
Authors: Coquelin M. , Pacher C. , Kast M. , Strasser G. , Gornik E.
Published: November 2006

The complex interplay of coherent and incoherent transmission channels in biased biperiodic superlattices is studied utilizing hot‐electron spectroscopy. It is found that coherent transport through the superlattices is dominated by the progressive localization of the Wannier–Stark states of two subminibands. This electric field dependence is lifted at special superlattice bias conditions where anticrossings between the Wannier‐Stark states of neighboring subminibands are induced. Additionally, LO‐phonon mediated transmission channels open up at electric fields where the Wannier–Stark splitting between individual states exceeds the LO‐phonon energy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recent developments in single dot coherent devices
Authors: Zrenner A. , Stufler S. , Ester P. , Michaelis de Vasconcellos S. , Hübner M. , Bichler M.
Published: November 2006

In the current contribution we review the physics of single quantum dot photodiodes. The coupling of a quantum system to an electric circuit allows for impressively simple and reliable single quantum measurements. The application of this concept leads to a new class of coherent optoelectronic devices with novel and so far unattained functionalities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural parameters and transition pressures of ZnO: ab‐initio calculations
Authors: Saib S. , Bouarissa N.
Published: November 2006

The structural parameters of ZnO in three phases, namely wurtzite, zincblende and rocksalt as well as transition pressures from wurtzite and zincblende to rocksalt structures are presented. Besides, the elastic constants in the three considered phases are reported. The calculations are performed using an ab‐initio pseudopotential study within the framework of the density‐functional theory (DFT) with both the local density approximation (LDA) and the generalized gradient approximation (GGA). Detailed comparisons are made with published experimental and theoretical results and show generally good agreement. Moreover, in most cases the present results are improved with respect to experiment when compared with previous calculations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Collective effects in radiation force on movable quantum dots
Authors: Iida Takuya , Ishihara Hajime
Published: November 2006

We theoretically study the resonant radiation force (RF) exerted on interacting quantum dots (QDs). For this purpose, the analytical expression of RF is derived based on the nonlocal theory and the Lorentz force equation. This explicitly shows how RF on QDs behaves under optical excitation of photomediated coupled‐states of polaritons in respective QDs confining excitons. In particular, if three QDs are aligned perpendicular to the optical axis, the negative dissipative (scattering and absorbing) force, whose direction is opposite to the light propagation direction, is exerted on the middle QD due to the phase inversion of the induced polarization in it. Furthermore, indirect attractive and repulsive forces arise between QDs at both ends via the middle QD. These effects would enable us to control the spatial dynamics of a QD‐assembly by exciting their collective modes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the photoconductivity of layered molecular complex of fullerene C60 with saturated amine TMPDA
Authors: Golovin Yu. I. , Lopatin D. V. , Rodaev V. V. , Konarev D. V. , Litvinov A. L. , Lyubovskaya R. N.
Published: November 2006

It was revealed that the photoconductivity of layered molecular complex of fullerene C60 with saturated amine TMPDA: TMPDA · C60 is caused by intermolecular electronic processes in the fullerene layers. The intermediate magneto‐sensitive stage of photogenerating free charge carriers was found to be due to the effect of magnetic field on the rate constant of the triplet charge transfer exciton annihilation process. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Attack–norm separation for detecting attack‐induced quality problems on computers and networks
Authors: Ye Nong , Chen Qiang
Published: November 2006

Cyber attacks on computer and network systems induce system quality and reliability problems, and present a significant threat to the computer and network systems that we are heavily dependent on. Cyber attack detection involves monitoring system data and detecting the attack‐induced quality and reliability problems of computer and network systems caused by cyber attacks. Usually there are ongoing normal user activities on computer and network systems when an attack occurs. As a result, the observed system data may be a mixture of attack data and normal use data (norm data). We have established a novel attack–norm separation approach to cyber attack detection that includes norm data cancelation to improve the data quality as an important part of this approach. Aiming at demonstrating the importance of norm data cancelation, this paper presents a set of data modeling and analysis techniques developed to perform norm data cancelation before applying an existing technique of anomaly detection, the chi‐square distance monitoring (CSDM), to residual data obtained after norm data cancelation for cyber attack detection. Specifically, a Markov chain model of norm data and an artificial neural network (ANN) of norm data cancelation are developed and tested. This set of techniques is compared with using CSDM alone for cyber attack detection. The results show a significant improvement of detection performance by CSDM with norm data cancelation over CSDM alone. Copyright © 2006 John Wiley & Sons, Ltd.
Cuscore control charts for generalized feedback‐control systems
Authors: Nembhard Harriet Black , Chen Shuohui
Published: November 2006

The cumulative score (Cuscore) statistic is devised to ‘resonate’ with deviations or signals of an expected type. When a process signal subject to feedback control occurs, it results in a fault signature in the output error. In this paper, Cuscore statistics are designed to monitor process parameters and characteristics measured by a generalized minimum variance (GMV) feedback‐control system sensitive to the fault signature of a spike, step, and bump signal. In this study, the GMV considered is a first‐order dynamic system with autoregressive moving average (ARMA) noise. We show theoretically that the performance of Cuscore charts is independent of the amount of variability transferred from the output quality characteristic to the adjustment actions in the GMV control system. Simulation is used to test the performance using the Cuscore charts. In general, the Cuscore can detect signals over a broad range of system parameter values. However, areas of low detection capability occur for certain fault signatures. In these cases, a tracking signal test is combined with the Cuscore statistics to improve detection performance. This study provides several illustrations of the underlying behavior and shows how the methodology developed can be easily applied in practice. Copyright © 2006 John Wiley & Sons, Ltd.
Winning customer loyalty in an automotive company through Six Sigma: a case study
Authors: Kumar Maneesh , Antony Jiju , Antony Frenie Jiju , Madu Christian N.
Published: November 2006

Six Sigma is a disciplined approach to improving product, process and service quality. Since its inception at Motorola in the mid 1980s Six Sigma has evolved significantly and continues to expand to improve process performance, enhance business profitability and increase customer satisfaction. This paper presents an extensive literature review based on the experiences of both academics and practitioners on Six Sigma, followed by the application of the Define, Measure, Analyse, Improve, Control (DMAIC) problem‐solving methodology to identify the parameters causing casting defects and to control these parameters. The results of the study are based on the application of tools and techniques in the DMAIC methodology, i.e. Pareto Analysis, Measurement System Analysis, Regression Analysis and Design of Experiment. The results of the study show that the application of the Six Sigma methodology reduced casting defects and increased the process capability of the process from 0.49 to 1.28. The application of DMAIC has resulted in a significant financial impact (over U.S. $110 000 per annum) on the bottom‐line of the company. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry
Authors: Silva Eduarda M. P. , Serra Vanda Vaz , Ribeiro Anderson O. , Tomé João P. C. , Domingues Pedro , Faustino M. Amparo F. , Neves M. Graça P. M. S. , Tomé Augusto C. , Cavaleiro José A. S. , Ferrer‐Correia António J. , Iamamoto Yassuko , Domingues M. Rosário M.
Published: November 2006

Novel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI‐MS/MS). The electrospray mass spectra (ESI‐MS) show the M+ ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI‐MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (−163 or −243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (−162 or −242 Da) and cross‐ring fragmentations typical of glyco‐derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic β‐pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C5–C6 bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI‐MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit. Copyright © 2006 John Wiley & Sons, Ltd.
Electron ionization mass spectra of phosphorus‐containing heterocycles. III. 1,3,4,2‐Oxadiazaphosphinane 2‐oxides
Authors: Juhász Márta , Zalán Zita , Fülöp Ferenc , Pihlaja Kalevi
Published: November 2006

The 1,3,4,2‐oxadiazaphosphinane 2‐oxides differ not only in the relative configuration of the P atom (R* or S*), but also in many other ways such as the ring size, ring fusion, P substitution and bridgehead N atom whose effects on their fragmentations have been studied. Some fragmentations resembled those of 3,1,2‐oxazaphosphinane 2‐oxides and 1,3,2‐diazaphosphinane‐2‐oxides, but new routes were also found, initiated by ionization at the bridgehead N atom. The relative abundances of the molecular ions and some fragment ions allowed the differentiation of cis‐trans epimers. Compounds with n = 2 and R  N(CH2CH2Cl)2, and linearly or angularly isoquinoline‐fused isomers in most cases, gave more numerous ions with lower relative abundances than the other compounds in this series. Only the isoquinoline derivatives provided fragments resulting from ionization of the aromatic part of the molecule. Copyright © 2006 John Wiley & Sons, Ltd.
First observation of cylindrospermopsin in Anabaena lapponica isolated from the boreal environment (Finland)
Authors: Spoof Lisa , Berg Katri A. , Rapala Jarkko , Lahti Kirsti , Lepistö Liisa , Metcalf James S. , Codd Geoffrey A. , Meriluoto Jussi
Published: November 2006

The cyanobacterial cytotoxin cylindrospermopsin has been mostly associated with cyanobacteria present in tropical and subtropical regions. Cylindrospermopsin has recently been found in cyanobacterial samples in central and southern Europe but the possible presence of the toxin in northern Europe has been unknown. Fifty‐eight field and laboratory culture samples of Finnish cyanobacteria were analyzed by high‐performance liquid chromatography combined with UV diode‐array detection, multiple reactant monitoring in a triple‐quadrupole mass spectrometer (MS), and accurate mass measurements using a time‐of‐flight MS instrument. Cylindrospermopsin was confirmed by all three techniques in a culture sample of Anabaena lapponica at a concentration of 242 μg cylindrospermopsin per g freeze‐dried cyanobacterial material. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 552–560, 2006.
Toxicity and modulations of biomarkers in Xenopus laevis embryos exposed to polycyclic aromatic hydrocarbons and their N‐heterocyclic derivatives
Authors: Burýšková Blanka , Hilscherová Klára , Bláha Luděk , Maršálek Blahoslav , Holoubek Ivan
Published: November 2006

Effects of a newly identified group of organic environmental pollutants of concern (N‐heterocyclic derivatives of polycyclic aromatic hydrocarbons, NPAHs) were investigated using the 96 h FETAX (Frog Embryo Teratogenesis Assay – Xenopus). Beside standard FETAX parameters (mortality, malformations), changes in several biochemical markers were studied as early signs of intoxication. Biomarkers included determination of glutathione (GSH) levels and lipid peroxidation as well as activities of important detoxification and antioxidant enzymes (glutathione‐S‐transferase, glutathione peroxidase, glutathione reductase). 1,10‐Phenathroline was the most toxic of all tested compounds (96 h LC50 = 4 μM). All tested NPAHs induced malformations in the frog embryos. The data suggest that the exposure to NPAHs can induce oxidative stress in amphibians; most biochemical markers were modulated at concentrations lower than those resulting in significant mortality. Results document mortality and teratogenicity of all studied NPAHs to amphibian embryos while no significant mortality, teratogenicity or modulations in biochemical markers could be observed with unsubstituted polycyclic aromatic hydrocarbons (PAHs) at concentrations up to their water solubility. This information along with the significantly greater solubility and thus bioavailability compared to their nonsubstituted parent compounds suggests that NPAHs could contribute significantly to the overall aquatic toxicity of mixtures of PAHs and their derivatives. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 590–598, 2006.
Acute toxicity, behavioral changes, and histopathological effects of deltamethrin on tissues (gills, liver, brain, spleen, kidney, muscle, skin) of Nile tilapia (Oreochromis niloticus L.) fingerlings
Authors: Yildirim M. Zıynet , Benlı A. Çağlan Karasu , Selvı Mahmut , Özkul Ayhan , Erkoç Fıgen , Koçak Oner
Published: November 2006

Deltamethrin, a synthetic pyrethroid contaminating aquatic ecosystems as a potential toxic pollutant, was investigated in the present study for acute toxicity. The purpose of this study was to evaluate LC50 values of deltamethrin on Nile tilapia (Oreochromis niloticus L.) fingerlings and investigate histopathological responses of fish exposed to deltamethrin. The 48 h LC50 value for Nile tilapia fingerlings was estimated as 4.85 μg/L using static test system. In addition, behavioral changes at each deltamethrin concentration were observed closely. All fish, exposed to 5 μg/L deltamethrin revealed severe morphological alterations in the gills and liver. In the gills hyperemia, fusion of secondary lamellae and telangiectasis were observed; whereas hydropic degenerations in liver were observed in all examined fish. The results are significant for reporting acute deltamethrin toxicity in terms of behavioral and histopathological changes: Deltamethrin is highly toxic to fingerlings. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 614–620, 2006.
Bilinear control system with the reaction‐diffusion term satisfying Newton's law
Authors: Lin P. , Leid P. , Gao H.
Published: November 2006

In this paper, we discuss a parabolic system governed by bilinear control, modeled according to Newton's Law. At first we prove that the system is exactly null controllable in long time T > 0 by locally distributed bilinear control and we further prove the exact null controllability in long time T > 0 of the semilinear parabolic equation yt‐Δ y + b |∇ y|2=ξou with traditionally additive locally distributed control and the existence of the control optimal time for the system. Then, we deduce an exact controllability result to particular stationary functions when we are acting over the whole domain and to particular stationary functions vanishing outside some ball included in the control domain when the control domain is as small as we want.
Enzyme, medium, and reaction engineering to design a low‐cost, selective production method for mono‐ and dioleoylglycerols
Authors: Arcos J. A. , Otero C.
Published: November 2006

The selective enzymic production of mono‐ and diolein (MO, DO) was optimized at high yields. A comparative study of the following distinct enzymic reactions was conducted: ethyl oleate glycerolysis, triolein (TO) glycerolysis, and direct esterification Solvent‐free systems were compared with media that contained different solvents. Native, modified (with polyethylene glycol), and immobilized lipases were used. Mechanical resistance, the support effect on enzyme and glycerol dispersion and on process reproducibility, and hydrophilicity of the support were considered in the process optimization. We report the use of an immobilized lipase on an inorganic support (Celite), which has high activities in both solid‐phase glycerolysis (99% reaction conversion) and esterification (100% conversion). The optimum conditions for the distinct reactions were compared by considering their selectivities, conversions, yields, and cost of the substrates. We found less costly and more selective processes in the absence of solvents for glycerolysis of triolein and direct esterification. Although glycerolysis was the most interesting process to produce diolein, esterification was better for monoolein preparation with this biocatalyst. The esterification reaction yielded 93 wt% of MO, in the absence of either TO or oleic acid (OA), at low cost because of the 100% reaction conversion. Similar costs of the substrates (10.6 and 10.1 $/g) were necessary to obtain 67 and 80 wt% of DO in esterification and glycerolysis, respectively. The glycerolysis conversion was 96%. In esterification, the product mixture was impure, with a high amount of residual OA due to the low conversion (59%). The high activity of PSL‐Celite in these solid‐phase reactions has an advantage over the reactions with nonimmobilized lipases due to the ease of enzyme recovery. The absence of organic solvents reduces the need for solvent removal from the reaction mixtures.
Lipid adsorption on commercial silica hydrogels from hexane and changes in triglyceride complexes with time
Authors: Proctor A. , Adhikari C. , Blyholder G. D.
Published: November 2006

The structures of and lipid complexes with two commercial silica hydrogels (Trisyl and Sorbsil 40), which contain about 60% moisture, were examined by diffuse reflectance Fourier transform infrared spectroscopy. The spectra suggested that Trisyl contained less moisture than Sorbsil 40. However, the silanol groups of Sorbsil 40 were more active in adsorbing oleic acid, triglyceride, and phosphatidylcholine (PC) from hexane than those of Trisyl. Both adsorbents strongly bound PC through the PC carbonyl and phosphate groups. Lipid adsorption from hexane solution by Trisyl depended solely on trapped moisture, while Sorbsil 40 used moisture and silanol groups on the silica surface. Spectra of triglyceride‐silica hydrogel complexes, obtained 24 and 72 h after obtaining the initial spectra, showed that Sorbsil 40 adsorption was by Van der Waals forces, but the triglyceride reoriented over time with an increase in hydrogen bonding. In contrast, Trisyl initially adosorbed triglyceride by hydrogen bonding which was stable for at least 72 h.
Conversion of oils to monoglycerides by glycerolysis in supercritical carbon dioxide media
Authors: Temelli Feral , King Jerry W. , List Gary R.
Published: November 2006

Glycerolysis of soybean oil was conducted in a supercritical carbon dioxide (SC‐CO2) atmosphere to produce monoglycerides (MG) in a stirred autoclave at 150–250°C, over a pressure range of 20.7–62.1 MPa, at glycerol/oil molar ratios between 15–25, and water concentrations of 0–8% (wt% of glycerol). MG, di‐, triglyceride, and free fatty acid (FFA) composition of the reaction mixture as a function of time was analyzed by supercritical fluid chromatography. Glycerolysis did not occur at 150°C but proceeded to a limited extent at 200°C within 4 h reaction time; however, it did proceed rapidly at 250°C. At 250°C, MG formation decreased significantly (P<0.05) with pressure and increased with glycerol/oil ratio and water concentration. A maximum MG content of 49.2% was achieved at 250°C, 20.7 MPa, a glycerol/oil ratio of 25 and 4% water after 4 h. These conditions also resulted in the formation of 14% FFA. Conversions of other oils (peanut, corn, canola, and cottonseed) were also attempted. Soybean and cottonseed oil yielded the highest and lowest conversion to MG, respectively. Conducting this industrially important reaction in SC‐CO2 atmosphere offered numerous advantages, compared to conventional alkalicatalyzed glycerolysis, including elimination of the alkali catalyst, production of a lighter color and less odor, and ease of separation of the CO2 from the reaction products.
Moderate antioxidative efficiencies of flavonoids during peroxidation of methyl linoleate in homogeneous and micellar solutions
Authors: Roginsky V. A. , Barsukova T. K. , Remorova A. A. , Bors W.
Published: November 2006

The relative reactivities as well as the stoichiometric coefficients for a number of flavonoids, catechols, and—for comparison—standard phenolic antioxidants were determined by analyzing the kinetics of oxygen consumption in organic and micellar systems, with peroxidation initiated by lipid‐ and water‐soluble azo initiators. The results demonstrated that the flavonoids did not behave as classic phenolic antioxidants such as α‐tocopherol, but showed only moderate chain‐breaking activities. The results were in line with other structure‐activity relationship studies on the importance of the B‐ring catechol structure, the 2,3‐double bond, and the 3,5‐hydroxy groups. The data are discussed in view of possible explanations of the deviations flavonoids reveal in their behavior compared with regular phenolic antioxidants.
Seed oils ofAcacia holosericea A. Cunn. ex G. Don.: Characteristics and composition
Authors: Prasad N. B. L. , Azeemoddin G.
Published: November 2006

Like the fruits ofElaeis guineensis, the seeds ofAcacia holosericea have two types of oils. One is present in the yellow aril (56%), which is attached to the black seed, and the other is in the kernel of the seed (12%). The proximate composition of seed and the physicochemical characteristics of the solvent‐extracted oils are reported. The aril fat is quite different from the seed oil in all respects. In descending order, the major fatty acids in aril fat are 18∶1 (54.35%), 16∶0 (29.3%), and 18∶2 (8.0%), whereas in seed (−aril) oil, the order is 18∶2 (59.45%) 18∶1 (20.2%), and 16∶0 (10.0%). In whole seed (+aril) oil, the order is 18∶2 (53.3%), 18∶1 (25%), 16∶0 (12.6).
Comparison of isopropanol and hexane for extraction of vitamin E and oryzanols from stabilized rice bran
Authors: Hu Weicheng , Wells John Henry , Shin Tai‐Sun , Godber J. Samuel
Published: November 2006

The effects of solvent‐to‐bran ratio (2∶1 and 3∶1, w/w), extraction temperature (40 and 60°C), and time (5, 10, 15, 20, and 30 min) were studied for hexane and isopropanol extraction. Increasing the solvent‐to‐bran ratios and extraction temperature increased the amounts of crude oil, vitamin E and oryzanol recovered for both solvents. An extraction time of 15 min was sufficient for optimum crude oil, vitamin E, and oryzanol extraction. Preheated isopropanol (3∶1 solvent/bran ratio and 60°C) extracted less crude oil (P<.05) but more vitamin E (P<.05) and similar amounts of oryzanol (P>.05) relative to preheated hexane. The data suggest that isopropanol is a promising alternative solvent to hexane for extraction of oil from stabilized rice bran.
Influence of pH and salt concentration on protein solubility, emulsifying and foaming properties of sesame protein concentrate
Authors: Inyang U. E. , Iduh A. O.
Published: November 2006

The effects of pH and NaCl concentration on protein solubility, emulsification, and foamability of sesame protein concentrate from dehulled seeds were investigated. The protein content of the concentrate was 70.7%. Protein solubility, emulsion, and foaming capacities varied with pH and ionic strength. Protein solubility, which was least at pH 4, (2.1%) ranged from 6.6% at pH 2 to 13.1% at pH 10. The solubility increased with increase in ionic strength, ranging from 9.8% at 0.0 M to 16.1% at 1.0 M concentration. The emulsion capacity ranged from 6.2 mL oil/g sample at pH 2 to 19.4 mL oil/g sample at pH 10. The emulsion capacity increased from 11.5 mL oil/g sample at 0.0 M to 20.9 mL oil/g sample at 1.0 M salt concentration. Stability of the emulsion increased with increase in NaCl concentration, ranging from 42% at 0.0 M concentration to 70% at 1.0 M concentration, but 0.5 M NaCl produced the most stable foam after 120 min of whipping while the least stable was at 1.0 M.
Emulsifying capacity of coconut proteins as a function of salt, phosphate, and temperature
Authors: Kwon K. S. , Rhee K. C.
Published: November 2006

Nitrogen solubilities of proteins in defatted coconut flour (CF) and coconut protein concentrate (CPC), prepared by ultrafiltration, were determined in water and 2% NaCl. The effect of temperature, disodium phosphate, and salt on emulsifying capacities (EC) of these products also were investigated by a model system. Between pH 4.0 and 5.0, nitrogen solubilities of CF and CPC in water were lower than those in salt solutions. In salt solutions, the nitrogen solubility was lowest at pH 1, and increased steadily as pH increased from 3.0 to 6.0. CF had higher EC values than CPC at all salt and phosphate levels. Additionally, increased phosphate level generally increased the EC at both salt levels, but these increases were not significant at 0.9% phosphate level as compared to the 0.7% phosphate level (P<0.05). Although the emulsifying temperature of 40°C showed higher EC values than both 60 and 80°C at all salt and phosphate levels, the overall temperature effect was not significant (P>0.05). However, EC decreased significantly with the addition of salt at all phosphate levels.
γ‐Linolenic and stearidonic acids in Mongolian Boraginaceae
Authors: Tsevegsüren Nanzad , Aitzetmüller Kurt
Published: November 2006

Seeds of nine Central Asian species of Boraginaceae were investigated for the first time for their oil content and for the fatty acid composition of their seed oils by capillary gas chromatography. Levels of γ‐linolenic acid ranged from 6.6 to 13.0% and levels of stearidonic acid ranged from 2.4 to 21.4% of total seed fatty acids. The seed oil ofHackelia deflexa exhibited the highest stearidonic acid content (21.4%) that has been found so far in nature. Other high contents of this fatty acid were in threeLappula species (17.2 to 18.1%). Seed oils ofCynoglossum divaricatum andAmblynotus rupestris contain considerable amounts ofcis‐11‐eicosenoic (5.3 to 5.8%) andcis‐13‐docosenoic acid (7.0 to 9.7%) besides γ‐linolenic (10.2 to 13.0%) and stearidonic acid (2.4 to 6.5%), which distinguish these oils from those of other Boraginaceae genera.
Supercritical fluid chromatographic analysis of new crop seed oils and their reactions
Authors: Hayes Douglas G. , Kleiman Robert
Published: November 2006

Supercritical fluid chromatography (SFC) with an open tubular column of nonpolar stationary phase separated triglycerides from crambe, meadowfoam,Euphorbia lagascae, and vernonia oils based on their molecular weight. The triglyceride compositions were consistent with the literature. SFC proved also to be a valuable tool in analyzing lipase‐catalyzed transesterification reactions where lesquerella oil and estolides were among the substrates employed. Analyte molecular weights could be estimated from a retention time‐ (or elution density‐) molecular eeight calibration curve. An increase in isothermal column temperature during SFC pressure or density programming improved the resolution of high‐molecular‐weight (>600 Da) analytes but yielded poorer resolution for analytes of molecular weight <200. A simultaneous pressure and temperature ramping program proved superior in enhancing resolution in several instances.
Improving the low‐temperature properties of alternative diesel fuels: Vegetable oil‐derived methyl esters
Authors: Dunn R. O. , Shockley M. W. , Bagby M. O.
Published: November 2006

This work explores near‐term approaches for improving the low‐temperature properties of triglyceride oil‐derived fuels for direct‐injection compression‐ignition (diesel) engines. Methyl esters from transesterified soybean oil were evaluated as a neat fuel and in blends with petroleum middle distillates. Winterization showed that the cloud point (CP) of methyl soyate may be reduced to −16°C. Twelve cold‐flow additives marketed for distillates were tested by standard petroleum methodologies, including CP, pour point (PP), kinematic viscosity, cold filter plugging point (CFPP), and low‐temperature flow test (LTFT). Results showed that additive treatment significantly improves the PP of distillate/methyl ester blends; however, additives do not greatly affect CP or viscosity. Both CFPP and LTFT were nearly linear functions of CP, a result that compares well with earlier studies with untreated distillate/methyl ester blends. In particular, additives proved capable of reducing LTFT of neart methyl esters by 5–6°C. This work supports earlier research on the low‐temperature properties; that is, approaches for improving the cold flow of methyl ester‐based diesel fuels should continue to focus on reducing CP.