bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards the sequential assimilation of SAR-derived water stages into hydraulic models using the Particle Filter: proof of concept
Authors: Matgen P. , Montanari M. , Hostache R. , Pfister L. , Hoffmann L. , Plaza D. , Pauwels V. R. N. , De Lannoy G. J. M. , De Keyser R. , Savenije H. H. G.
Published: September 2010

Abstract. With the onset of new satellite radar constellations (e.g. Sentinel-1) and advances in computational science (e.g. grid computing) enabling the supply and processing of multi-mission satellite data at a temporal frequency that is compatible with real-time flood forecasting requirements, this study presents a new concept for the sequential assimilation of Synthetic Aperture Radar (SAR)-derived water stages into coupled hydrologic-hydraulic models. The proposed methodology consists of adjusting storages and fluxes simulated by a coupled hydrologic-hydraulic model using a Particle Filter-based data assimilation scheme. Synthetic observations of water levels, representing satellite measurements, are assimilated into the coupled model in order to investigate the performance of the proposed assimilation scheme as a function of both accuracy and frequency of water level observations. The use of the Particle Filter provides flexibility regarding the form of the probability densities of both model simulations and remote sensing observations. We illustrate the potential of the proposed methodology using a twin experiment over a widely studied river reach located in the Grand-Duchy of Luxembourg. The study demonstrates that the Particle Filter algorithm leads to significant uncertainty reduction of water level and discharge at the time step of assimilation. However, updating the storages of the model only improves the model forecast over a very short time horizon. A more effective way of updating thus consists in adjusting both states and inputs. The proposed methodology, which consists in updating the biased forcing of the hydraulic model using information on model errors that is inferred from satellite observations, enables persistent model improvement. The present schedule of satellite radar missions is such that it is likely that there will be continuity for SAR-based operational water management services. This research contributes to evolve reactive flood management into systematic or quasi-systematic SAR-based flood monitoring services.
Spatial interpolation of daily rainfall at catchment scale: a case study of the Ourthe and Ambleve catchments, Belgium
Authors: Ly S. , Charles C. , Degré A.
Published: September 2010

Abstract. Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (krigings) are widely used in spatial interpolation from point measurement to continuous surfaces. However, the majority of existing geostatistical algorithms are available only for single-moment data. The first step in kriging computation is the semi-variogram modelling which usually uses only one variogram model for all-moment data. The objective of this paper was to develop different algorithms of spatial interpolation for daily rainfall on 1 km2 regular grids in the catchment area and to compare the results of geostatistical and deterministic approaches. In this study, we used daily rainfall data from 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km2). This area lies between 35 and 693 m in elevation and consists of river networks, which are tributaries of the Meuse River. For geostatistical algorithms, Cressie's Approximate Weighted Least Squares method was used to fit seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) to daily sample semi-variogram on a daily basis. Seven selected raingages were used to compare the interpolation performance of these algorithms applied to many degenerated-raingage cases. Spatial interpolation with the geostatistical and Inverse Distance Weighting (IDW) algorithms outperformed considerably interpolation with the Thiessen polygon that is commonly used in various hydrological models. Kriging with an External Drift (KED) and Ordinary Cokriging (OCK) presented the highest Root Mean Square Error (RMSE) between the geostatistical and IDW methods. Ordinary Kriging (ORK) and IDW were considered to be the best methods, as they provided smallest RMSE value for nearly all cases.
Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy
Authors: Budetta P.
Published: September 2010

Abstract. On 10 January 2003, a rockfall of approximately 10 m3 affected a cliff some 25 m high located along the northern slopes of Mt. St. Angelo (Nocera Inferiore, province of Salerno) in the southern Italian region of Campania. The impact of boulders on the lower sector of the slope, along which detrital-pyroclastic soils outcrop, triggered a small channelled debris flow of about 500 m3. Fortunately, no damage nor victims resulted from the landslide. Several marks of the impacts were observed at the cliff toe and outside the collapsed area, and the volumes of some fallen boulders were subsequently measured. By means of in-situ surveys, it was possible to reconstruct the cliff's geo-structural layout in detail. A rockfall back-analysis was subsequently performed along seven critical profiles of the entire slope (surface area of about 4000 m2). The results of this numerical modelling using the lumped-mass method were then used to map the kinetic iso-energy curves. In the triggering area of the debris flow, for a falling boulder of 1 m3, the mean kinetic energy was estimated at 120 kJ, this value being equivalent to an impact force, on an inclined surface, of some 800 kN. After landing, due to the locally high slope gradient (about 45°), and low angle of trajectory at impact (about 23°), some boulders slid down the slope as far as the endpoints. The maximum depth of penetration into the ground by a sliding block was estimated at about 16 cm. Very likely, owing to the high impact force of boulders on the saturated soil slope outcropping at the cliff base, the debris flow was triggered under undrained loading conditions. Initial failure was characterized by a translational slide involving a limited, almost elliptical area where the pyroclastic cover shows greater thickness in comparison with the surrounding areas.
Spatial distribution of pingos in Northern Asia
Authors: Grosse G. , Jones B. M.
Published: September 2010

Abstract. Pingos are prominent periglacial landforms in vast regions of the Arctic and Subarctic. They are indicators of modern and past conditions of permafrost, surface geology, hydrology and climate. A first version of a detailed spatial geodatabase of more than 6000 pingo locations in a 3.5 × 106 km2 region of Northern Asia was assembled from topographic maps. A first order analysis was carried out with respect to permafrost, landscape characteristics, surface geology, hydrology, climate, and elevation datasets using a Geographic Information System (GIS). Pingo heights in the dataset vary between 2 and 37 m, with a mean height of 4.8 m. About 64% of the pingos occur in continuous permafrost with high ice content and thick sediments; another 19% in continuous permafrost with moderate ice content and thick sediments. The majority of these pingos likely formed through closed system freezing, typical of those located in drained thermokarst lake basins of northern lowlands with continuous permafrost. About 82% of the pingos are located in the tundra bioclimatic zone. Most pingos in the dataset are located in regions with mean annual ground temperatures between −3 and −11 °C and mean annual air temperatures between −7 and −18 °C. The dataset confirms that surface geology and hydrology are key factors for pingo formation and occurrence. Based on model predictions for near-future permafrost distribution, hundreds of pingos along the southern margins of permafrost will be located in regions with thawing permafrost by 2100, which ultimately may lead to increased occurrence of pingo collapse. Based on our dataset and previously published estimates of pingo numbers from other regions, we conclude that there are more than 11 000 pingos on Earth.
Synthesis, Reductive Cleavage, and Cellular Interaction Studies of Biodegradable, Polyglycerol Nanogels
Authors: Steinhilber Dirk , Sisson Adam L. , Mangoldt Dorothea , Welker Pia , Licha Kai , Haag Rainer
Published: September 2010

In this paper we describe disulfide containing, polyglycerol nanogels as a new class of biodegradable materials. These nanoparticles are prepared in inverse miniemulsion via an acid catalyzed ring‐opening polyaddition of disulfide containing polyols and polyepoxides. Varying conditions allow us to tune particle size and disulfide content within the polymer network; particles can be prepared with narrow polydispersities and diameters in the range from 25 to 350 nm. Particle degradation under reductive intracellular conditions is studied by various analytical techniques. Gel permeation chromatography indicates that final degradation products have relatively low molecular weights (≤ 5 kDa). In addition, studies in cell culture show these nanoscale materials to be highly biocompatible. Dye‐labelled nanogels are shown by optical microscopy techniques to readily internalize into cells by endocytotic mechanisms. This study highlights the great potential of these particles to function as sophisticated nanotransporters that deliver cargo to a certain tissue or cell target and then biodegrade into smaller fragments which would be cleared from the body by the kidney. (with ≈ 30 kDa molecular weight cut off)
Antimicrobial hydrogels formed by crosslinking polyallylamine with aldaric acid derivatives
Authors: Andrews Mark A. , Figuly Garret D. , Chapman John S. , Hunt Todd W. , Glunt C. Darrel , Rivenbark Jeff A. , Chenault H. Keith
Published: September 2010

Aqueous dispersions (0.1 wt %) of hydrogels 1 and 5—formed by crosslinking polyallylamine hydrochloride (MW 60,000) with aldaric acid derivatives, diethyl L‐tartrate and N,N′‐bis(methoxycarbonylmethyl)‐D‐glucaramide, respectively—exhibited complete (log 5) kill within 4 h of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans suspended in culture medium. This antimicrobial activity was much higher than that of uncrosslinked polyallylamine (1 wt % killed only 75% of E. coli in 24 h). When dispersed at 10 and 100 ppm, hydrogel 5 displayed complete (log 5) kill of E. coli within 30–60 and 15 min, respectively. Hydrogels 1 and 5 were active against S. aureus and Salmonella choleraesuis dried on hard stainless steel surfaces and accelerated the deaths of E. coli, P. aeruginosa, S. aureus, and C. albicans in a model skin cream formulation. A 0.8% aqueous dispersion of hydrogel 5 was also effective as a hand sanitizer, killing 99.7% of Serratia marcescens on human hands within 5 min. Hydrogels 1 and 5 caused no dermal irritation or allergic contact sensitization under the conditions of a human repeat insult patch test. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Characterization of surface‐modified polyalkanoate films for biomedical applications
Authors: Garrido Leoncio , Jiménez Ignacio , Ellis Gary , Cano Pilar , García‐Martínez Jesús M. , López Laura , de la Peña Enrique
Published: September 2010

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBHV) films prepared by solvent casting were treated with oxygen, argon, and nitrogen radiofrequency‐generated plasmas. The analysis by attenuated total reflectance infrared spectroscopy and X‐ray absorption near edge spectroscopy of modified surfaces showed an increase of hydroxyl and unsaturated groups, compared with unmodified surfaces. Water contact angles decreased after a short time of exposure (<30 s) for all types of plasma. At long exposure times (>30 s), the water contact angles appeared to be independent of treatment time for nitrogen and argon plasmas, whereas they continuously decreased for films treated with oxygen. HaCaT cultures on nontreated and treated PHBHV films showed that short plasma exposures of 10–20 s improve cell attachment to a greater extent than long exposure times habitually used in polymer surface plasma treatment. The film surface topology did not influence cell attachment. These results illustrate the importance of a detailed characterization of the surface physicochemistry in plasma‐modified substrates designed as part of a strategy to optimize specific cell–biomaterial interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and property studies of N‐carboxymethyl chitosan
Authors: Song Qingping , Zhang Ze , Gao Jiangang , Ding Chunmei
Published: September 2010

N‐carboxymethyl chitosans (N‐CMC) were synthesized from chitosan in water with chloroacetic acid instead of comparatively expensive glyoxylic acid. The optimal reaction conditions were 90°C and 4 h with a ratio of chloroacetic acid to chitosan 5 : 1(w/w). The degree of substitution of product exceeded 1.32. The N‐carboxymethyl chitosans were characterized by XRD, FTIR, 1H‐NMR, and the water solubility and isoelectric point of N‐CMC with different degrees of substitution were determined. FTIR and 1H‐NMR data has confirmed that the substitution reaction occurred on the amino groups. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Using stimulus control procedures to teach indoor rock climbing to children with autism
Authors: Kaplan‐Reimer Hannah , Sidener Tina M. , Reeve Kenneth F. , Sidener David W.
Published: September 2010

The present study evaluated an intervention package for teaching route following to two children with autism at an indoor rock‐climbing gym. The intervention consisted of multiple within‐stimulus fading procedures in combination with errorless learning procedures, positive reinforcement, an error correction procedure, and conditional discrimination training technologies. The results demonstrated that both participants learned to climb at least 10 ft/3 m on specified routes. Furthermore, both participants learned to climb an entire 22‐ft/6.7‐m wall for at least one of three different routes without any errors in a regular rock‐climbing gym setting. The acquisition of this skill provides children with autism with an additional option for leisure participation with others. Copyright © 2010 John Wiley & Sons, Ltd.
A sensitive method for determination of trace amounts of chromate (III) with terbium (III) sodium hexametaphosphate chelate as fluorescent probe
Authors: Chen Hongqi , Chen Jingguo , Wang Lun , Zhou Cailing , Ling Bo , Fu Jie
Published: September 2010

Based on the fluorescence quenching of Terbium (III)‐sodium hexametaphosphate (Tb/SHMP) chelates in the presence chromate (III), a sensitive fluorimetric method was developed for the determination of trace amounts of chromium (III) in aqueous solutions. Under the optimum conditions, the linear calibration graph was obtained (R = 0.996). The linear range and detection limit of Cr (III) were 7.69 × 10−7 to 1.15 × 10−4 mol L−1 and 4.50 × 10−7 mol L−1, respectively. The proposed method had a wider linear range and was proved to be very sensitive, rapid and simple. The method was applied successfully to the determination of chromium (III) in the synthetic samples and real water samples. Moreover, the reaction mechanism was discussed through the fluorescence lifetime and proved to be dynamic quenching behavior. Copyright © 2010 John Wiley & Sons, Ltd.
Determination of pethidine in human plasma by LC–MS/MS
Authors: Wang Xianqin , Xiang Zheng , Cai Xiaojun , Wu Haiya , Wang Xuebao , Li Junwei , Zhang Meiling
Published: September 2010

A sensitive and selective liquid chromatography–tandem mass spectrometry method for the determination of pethidine in human plasma was developed and validated over the concentration range of 4–2000 ng/mL. After addition of ketamine as internal standard, liquid–liquid extraction was used to produce a protein‐free extract. Chromatographic separation was achieved on a 100 × 2.1 mm, 5 µm particle, AllureTM PFP propyl column, with 45:40:15 (v/v/v) acetonitrile–methanol–water containing 0.2% formic acid as mobile phase. The MS data acquisition was accomplished by multiple reactions monitoring mode with positive electrospray ionization interface. The lower limit of quantification was 4 ng/mL; for inter‐day and intra‐day tests, the precision (RSD) for the entire validation was less than 7%, and the accuracy was within 95.9–106.5%. The method is sensitive and simple, and was successfully applied to analysis of samples of clinical intoxication. Copyright © 2010 John Wiley & Sons, Ltd.
Development and validation of a rapid high‐performance liquid chromatography method for the quantification of exenatide
Authors: Bachhav Yogeshwar G. , Kalia Yogeshvar N.
Published: September 2010

The objective was to develop a simple HPLC method to quantify exenatide—a 39 amino acid residue incretin mimetic used in diabetes therapy. To date, only non‐validated, sometimes incomplete, gradient methods have been reported in the literature. Isocratic separation was achieved using a C4 column and a mixed solvent system, A–B–C (48:45:7, v/v/v; pH* 5.2), where A represents KH2PO4 (pH 4.5; 0.1 m) and MeCN (60:40, v/v), B corresponds to NaClO4·H2O (pH 6.0; 0.2 m) and MeCN (60:40, v/v), and C is water. Exenatide eluted at 3.64 min and the total run time was 6 min. The method was specific and the response was accurate, precise and linear from 0.75 to 25 µg/mL. It was used to quantify exenatide transport across intact and laser‐porated porcine skin in vitro as a function of laser fluence [0 (i.e. intact skin), 9 and 15 J/cm2, respectively]. Although no permeation was observed using intact skin, cumulative exenatide permeation after 8 h through laser porated skin was 9.6 ± 6.5 and 12.4 ± 6.4 µg/cm2 at fluences of 9 and 15 J/cm2, respectively. This is the first validated isocratic method for exenatide quantification and it may be of use in quality control analysis and with other biological matrices. Copyright © 2010 John Wiley & Sons, Ltd.
Kinetics of zinc and cadmium dissociation of metallothionein in the presence of chelating agents
Authors: Huang Zhong‐Xian , Hu Hong‐Yu , Gu Wei‐Qiang
Published: September 2010

The dissociation kinetics of metal ions from native metallothionein (Cd5Zn2‐MT) of rat liver has been studied in the presence of external ligands including amino acids, peptide and polyamino polycarboxylic acids at 25°C. The study shows that the solution pH affects the metal dissociation process. Different ligands present different multiphasic kinetics. The possible mechanism of metal dissociation from metallothionein has been proposed.
Synthesis, crystal and molecular structure of [Na(B15C5)+]2[Hg3Cl8]2‐·H2O
Authors: Tao Ting‐Chao , Ding Kui‐Ling , Wu Yang‐Jie , Zhu Ying
Published: September 2010

A crystal complex with the formula [Na(B15C5)+]2 [Hg3Cl8]2‐·H2O was synthesized by the reaction of benzo‐15‐crown‐5 with sodium chloride and mercuric chloride. Its crystal and molecular structures were determined by X‐ray diffraction. Crystal data: monoclinic, space group P2/n with cell dimensions of a= 17.809(4) Å, b= 13.938(4) Å, c= 17.984(4) Å, β=107.14°, Z=4, V= 4266.2 Å2. R and Rw are 0.043 and 0.053, respectively. The results obtained by spectral analysis are consistent with those of the structural analysis.
Intramolecular reaction and intramolecular catalysisd̊ II. Mechanism of intramolecular catalysis in hydrolysis of 2‐(2'‐benzimidazolyl)phenyl acetate by benzimidazolyl group
Authors: Xia Chi‐Zhong , Xia Dao‐Hong
Published: September 2010

As a model for acetyl‐α‐chymotrypsin, 2‐(2'‐benzimidazolyl)phenyl acetate was synthesized in a good yield and its hydrolytic kinetics has been studied in buffer solutions at 45'C within a wide pH range (0.65–8.80). The measured pseudo‐first‐order rate constants (kobs) at different pH values conform well with the data derived from the proposed theoretical model. It is shown that in an acidic solution of medium strength (pH = 2.0–3.0), the ester is hydrolyzed via intramolecular general acid catalysis by benzimidazolium cation; while at pH values near neutrality (pH = 5.5–7.0), this ester is hydrolyzed via intramolecular general base catalysis by neutral benzimidazole. These findings are discussed and the activation parameters of the hydrolysis reaction were also determined.
Lower photoreactivity of 3‐methyl‐3‐(4′‐biphenylyl)‐t‐butene
Authors: Wu Guo‐Sheng , Hu Jun , Li Jiang‐Pin , Xu Jian‐Hua
Published: September 2010

Direct and sensitized photolyses of 3‐methyl‐3‐(4′‐biphenylyl)‐1‐butene gave 1,1‐dimethyl‐2‐(4′‐biphenylyl)cyclopropane as primary product and 2‐methyl‐4‐(4′‐biphenylyl)‐1‐butene as secondary product with quantum yields of 7.6×10−3 and 5.6×10−3, respectively. On direct photolysis, the triplet reactant rearranged with a quantum yield of 4.4×10−3 and is more reactive than the singlet. The exceptionally low photoreactivity shows that the excitation energy is largely localized on the biphenylyl portion but can be delivered to the reaction center slowly.
New metabolites from the fungus Stereum purpureum
Authors: Xie Jin‐Lun , Li Li‐Ping
Published: September 2010

Two new sterpurene sesquiterpenes, 4,12‐dihydroxysterpurene (1) and 5,12‐dihydroxysterpurene (3), have been isolated from Stereum purpureum, and identified mainly on the basis of mass spectra and extensive nuclear magnetic resonance spectrometry, especially two‐dimensional NMR.
Zinc‐containing chainlike polymer {Cs2[Zn(S2C=C(CN)2)2]}n, the second example of bridging [S2C=C(CN)2]
Authors: Zhu Yong‐Bao , Lu Shao‐Fang , Huang Xiao‐Ying , Wu Qiang‐Jin , Zhang Yu‐Dong
Published: September 2010

The title compound {Cs2[Zn(S2C=C(CN)2)2]}n(2), Catena‐poly {dicesium [bis(1.1‐dicyanoethene‐2,2‐dithiolato‐S,S':N)‐Zinc(II)]}, is the second example of bridging [S2C=C(CN)2] (hereafter referred to as i‐mnt) for metal‐containing polymer. It crystallizes in the non‐centrosymmetric space group Ia (alt. Cc, No.9) There are two coordination modes of i‐mnt in this compound: μ‐ηl‐ηl‐i‐mnt, bridging two Zn moieties with two S atoms and terminal i‐mnt. A characteristic feature of the structure is the infinite ‐Zn(η2‐i‐mnt)(η1‐η1‐i‐mnt)‐Zn(η1‐η1‐i‐mnt)(η2‐i‐mnt)‐wav∼Like chain. Cs atoms are located between the chains to form three‐dimensional network‐like packing. An efficient second harmonic generation &om the crystal has been observed on the irradiation with the 1064 nm output of a Nd:YAG laser.
A Novel Method for Fixed‐node Quantum Monte Carlo
Authors: Huang Hong‐Xin , Zhao Zhen‐Hua
Published: September 2010

In this paper, a novel method for fixed‐node quantum Monte Carlo is given. By comparing this method with the traditional fixed‐node one, this novel method can be applied to calculate molecular energy more exactly. An expansion of the eigenvalue of the energy for a system has been derived. It is proved that the value of the energy calculated using the traditional fixed‐node method is only the zeroth order approximation of the eigenvalue of the energy. But when using this novel method, in the case of only increasing less computing amounts ( < 1%), the first order approximation, the second order approximation, and so on can be obtained conveniently with the detailed equations and steps in the practical calculation to calculate the values of the zeroth, first and second approximation of the energies of 1 1A, state of CH2, 1A2(C4h, acet) state of C8 and the ground‐states of H2, LiH, Li2, and H2O The results indicate that for these states it needs only the second order approximation to obtain over 97% of electronic correlation energy, which demonstrates that this novel method is very excellent in both the computing accuracy and the amount of calculation required.
Ab initio Study on the Intermolecular Interaction and Thermodynamic Properties of Methyl Nitrate Dimer
Authors: Tan Jin‐Zhi , Xiao He‐Ming , Gong Xue‐Dong , Li Jin‐Shan
Published: September 2010

Three stable dimers of methyl nitrate have been obtained and their geometries have been fully optimized at the HF/6‐31G,. level. Binding energies have been calculated with correction for the basis set superposition error (BSSE) and zero point energy (ZPE). The cyclic overlap‐type structure, the binding energy of which is 11.97 kJ/mol at the MP4SDTQ/6‐31G. / HF/6‐31G. level, is the most stable. No intermolecular hydrogen bond was found, and the charge transfer between two subsystems is minute. The thermodynamic properties of methyl nitrate and its dimers have been calculated based on the vibrational analysis and statistical thermodynamics.
Density Functional Studies of the CF Bond Activation of CF3 Radical by Bare Co+
Authors: Zhang Dong‐Ju , Liu Cheng‐Bu , Hu Hai‐Quan , Liu Yong‐Jun
Published: September 2010

The CF bond activation mechanism of CF3 radical by bare Co+ has been studied by density functional theory. Three local minima and two first‐order saddle points were located for the potential energy surface (PES) of [Co, C, F3]+. The activation barrier involving CF bond activation was calculated to be only 14.73 kJ/mol, while the largest barrier of 149.29 kJ/mol on the FES involves CoC bond rupture. The bonding mechanism between Co+, C and F atoms were discussed based on Mulliken population. The relevant bond dissociation energy and thermochemistry data were calculated with the limited experimental values, and the results are in good agreement with the experimental findings.
Fluorescence Spectral Studies on the Coordination of Calix[4]‐arenes Bearing Boronic Acid Moieties with Monosaccharides
Authors: Lu Kui , Wu Yang‐Jie , Li Yong‐Hong , Shi Ya‐Lin , Zhou Zhi‐Xian
Published: September 2010

Coordination of ten calix[4]arenes bearing boronic acid moieties with five monosaccharides was studied by fluorescence spectrometry. The stability constants (K2) of the complexes and Gibbs free energy change ( ‐ ΔG0) of the coordination reactions were calculated according to the modified Hilderbrand‐Benesi equation. The results obtained indicated that the coordination ability of D‐( ‐ )‐fructose with calix[4] arenes bearing boronic acid moieties was stronger than that of the other monosaccharides. And these calix[4]arene derivatives might be used for identification of L‐( ‐ )‐sorbose.
Structural Transformation of the Peptide Fragments from the Reactive Center Loops of Serpins: Circular Dichroic Studies
Authors: Hu Hong‐Yu , Chen Yun‐Neng , Xu Song‐Qin , Xu Gen‐Jun
Published: September 2010

Two peptides, derived from the reactive center of ovalbumin (OVARC) and plasminogen activator inhibitor‐1 (PAIRC) respectively were chemically synthesized and investigated by circular dichroic spectroscopy. The secondary structural transformation in solution and in solid state was studied. OVARC shows a nascent helical structure in aqueous solution, and its helical content increases under acidic conditions. There is no obvious structural conversion from solution to solid state. PAIRC, however, undergoes a structural transformation from random coil in aqueous solution to a typical β‐sheet structure in the solid state. Hexafluoroisopropanol (HFIP) prompts helical structures of the two peptides in solution, but it seems to trigger the structural formation of β‐sheets in solid state. The novel structural transformation from random coil or nascent helical structure in aqueous solution to the α‐helix in HFIP and to the β‐sheet structure in solid state may reflect the conformational polymorphism of the serpin reactive centers and is implicated in the structural features of the amyloid aggregates.
MCM‐41 Supported Aminopropylsiloxane Palladium Acetate Complex: A Highly Active and Stereoselective Catalyst for Heck Reaction
Authors: Zhou Jian‐Min , Zhou Ren‐Xian , Mo Liu‐Ye , Zhao Shao‐Fen , Zheng Xiao‐Ming
Published: September 2010

A new MCM‐41 supported aminopropylsiloxane palladium acetate was prepared and characterized. This catalyst is highly active and stereoselective for Heck reaction at 70°C.
Low‐valent Titanium Induced Reductive Coupling of O‐Nitrophenylazide with Benzoyl Substituted Ketene Dithioacetals: a Novel Synthesis of 4‐Aryl‐2‐methylthio‐3Z7‐l,5‐benzodiazepines
Authors: Li Zhi‐Fang , Zhang Yong‐Min
Published: September 2010

Treated with the low‐valent titanium derived from TiCl4/Sm system, o‐nitrophenylazide could produce the intermediate 2 in situ, which reacted with benzoyl substituted ketene dithioacetals to afford 4‐aryl‐2‐methylthio‐3H‐1,5‐benzodiazepines in good yields under mild and neutral conditions.
Synthesis, Characterization and Molecular Structure of Ternary Cu(II) Complex with 1, 4, 8, 9‐Tetraazatriphenylene and L‐Phenylaninate
Authors: Le Xue‐Yi , Yang Guang , Feng Xiao‐Long , Ji Liang‐Nian
Published: September 2010

The complex [Cu(L‐Phe)(TATP)(H2O)]ClO4.0.5H2O has been synthesized and investigated by elemental analysis, molar conductivity, spectroscopic and X‐ray diffraction methods, where TATP= 1,4,8,9‐tetraazatriphenylene and L‐phe = L‐phenylaninate group. The complex crystallizes in the triclinic space group PI with two molecules in a unit cell of dimensions a=0.5730(l), b = 1.0190(2), c = 2.1430(4), α= 97.50 (1)°, β = 95.33(3)°, γ= 102.85(1)°, V= 1.1998(4) nm3, R1 = 0.0360, wR2 = 0.0400. The crystal contains two independent [Cu(L‐Phe) (TATP)(H2O)]+ complexes Cu1 and Cu2, having essentially the same distorted square‐pyramidal structure, where each Cu(II) ion coordinates two nitrogen atoms of TATP and the amino nitrogen and carboxylate oxygen atoms of L‐Phe in the equatorial positions and one water oxygen at an axial position.
Interconnection of heterogeneous knowledge bases and its application on Knowledge Grid
Authors: Nakanishi T. , Zettsu K. , Kidawara Y. , Kiyoki Y.
Published: September 2010

Recently, the number of users who use search engines for not only retrieving Web pages but also understanding or learning an arbitrary concept has been increasing. However, it is difficult to understand and learn an arbitrary concept by using the existing search engines. This paper presents a method for the interconnection of heterogeneous knowledge bases on Knowledge Grid for knowledge sharing and provision. In this paper, for realizing the proposed method, we introduce two types of services—intra‐operation services and inter‐operation services—on Knowledge Grid. The system dynamically creates a semantic associative network that connects the user's interests and concepts, and provides correlation views that represent various relationships for connecting related resources. In addition, we employ a link‐free browsing system by this method called correlation browsing, which represents the semantic association utilizing collective knowledge by connecting various knowledge bases. The current web browsing has two actions—browsing and jumping by static hyperlinks. It is difficult to understand the relationship between each page that is connected by static hyperlink. The system navigates the related contents while repeatedly switching between a content browsing mode and a correlation browsing mode. Therefore, a user can access various contents while understanding the relationships. Copyright © 2010 John Wiley & Sons, Ltd.
A new approach for sparse matrix vector product on NVIDIA GPUs
Authors: Vázquez F. , Fernández J. J. , Garzón E. M.
Published: September 2010

The sparse matrix vector product (SpMV) is a key operation in engineering and scientific computing and, hence, it has been subjected to intense research for a long time. The irregular computations involved in SpMV make its optimization challenging. Therefore, enormous effort has been devoted to devise data formats to store the sparse matrix with the ultimate aim of maximizing the performance. Graphics Processing Units (GPUs) have recently emerged as platforms that yield outstanding acceleration factors. SpMV implementations for NVIDIA GPUs have already appeared on the scene. This work proposes and evaluates a new implementation of SpMV for NVIDIA GPUs based on a new format, ELLPACK‐R, that allows storage of the sparse matrix in a regular manner. A comparative evaluation against a variety of storage formats previously proposed has been carried out based on a representative set of test matrices. The results show that, although the performance strongly depends on the specific pattern of the matrix, the implementation based on ELLPACK‐R achieves higher overall performance. Moreover, a comparison with standard state‐of‐the‐art superscalar processors reveals that significant speedup factors are achieved with GPUs. Copyright © 2010 John Wiley & Sons, Ltd.
Performance evaluation of throughput in optical burst switching
Authors: Alam M. S. , Alsharif S. , Panati P.
Published: September 2010

Optical burst switching (OBS) provides a promising solution to utilize the huge terahertz bandwidth of optical wavelength division multiplexing (WDM) transmission technology. To exploit this bandwidth, several reservation schemes have been proposed that include just‐in‐time (JIT) signaling, just‐enough‐time (JET) signaling and burst segmentation (BS). It is necessary to investigate the performance of these schemes under the same constraints for a prescribed OBS application. Accordingly, in this paper, we analyzed and compared the performance of JIT, JET and BS techniques under various scenarios such as network size, delay variation and load variation in an OBS network using various performance metrics, such as the offset time and switch configuration time. Also, the performance of the network under various switching delays was also investigated. The modified BS reservation scheme has been found to yield significantly better performance and better throughput compared with the JIT and JET reservation schemes. Test results show that the effect of varying loads as well as delays significantly impacts the performance of the OBS network. The results presented in this paper are expected to lead further performance improvements in OBS networks using the BS reservation scheme. Copyright © 2010 John Wiley & Sons, Ltd.
Oxidative stress after kidney transplantation: The role of immunosuppression
Authors: Štrebl Pavel , Horčička Jr. Vladko , Krejči Karel , Horák Pavel , Vostálová Jitka , Zdařilová Adéla , Kajabová Markéta , Schneiderka Petr , Zadražil Josef
Published: September 2010

BACKGROUND

Oxidative stress (OS) is one of the consequences of kidney transplantation (KT). The level of OS can be monitored using the total antioxidative status (TAS) and parameters that result from damaged molecules, such as advanced oxidation protein products (AOPPs). The aim of this study was to monitor OS in patients before and after KT, and to evaluate the effect of immunosuppressive therapy on the level and development of OS.

METHODS

Participants in this prospective study were patients who underwent KT (n = 31; age 53.7% % 11.2 years; 20 males, 11 females). Patients were treated with immunosuppressives, cyclosporine (n = 18), or tacrolimus (n = 13). Clinical biochemistry, hematology, and OS parameters were measured on the day before KT and 1, 7, 30, and 90 days after KT.

RESULTS

On the 7th day after KT, patients showed a significant decrease in AOPP (p = .0001) and TAS (p = .031) compared with the levels before KT. The decrease in AOPP levels lasted until the 90th day after KT. On the 90th day after KT, AOPP levels non‐significantly decreased in patients treated with tacrolimus compared with patients treated with cyclosporine (median was 70.35 µmol/L and 131.1 µmol/L).

CONCLUSION

Successful KT reduced but did not normalize AOPP levels.
Entecavir treatment for chronic hepatitis B infection in end‐stage renal disease and kidney transplantation
Authors: Ridruejo Ezequiel , Adrover Raúl , Alonso Cristina , Mandó Oscar G. , Silva Marcelo O.
Published: September 2010

BACKGROUND

The prevalence of chronic hepatitis B virus (HBV) infection is high in patients with end‐stage renal disease and in kidney transplant recipients, and there is little experience with treatment using the newer antiviral drugs. The aim of this study was to assess the efficacy and safety of entecavir in HBV infection in this difficult‐to‐treat population.

METHODS

Eleven male patients—1 with stage 4 chronic kidney disease, 7 undergoing hemodialysis, and 3 kidney transplant recipients‐were included in the study evaluation. Six were treatment naïve, and 5 were lamivudine resistant. Entecavir was administered at a dose of 0.1–1 mg qd according to the patients' renal function. All were HBsAg positive: 9 were HBeAg (+)/antiHBe (−), and the remaining 2 were HBeAg (−)/antiHBe (+).

RESULTS

After a median treatment of 2 ± 0.86 years, entecavir therapy was associated with a significant decrease in HBV DNA viral load: it was 6.84 ± 1.45 log10 UI/mL (range 5.21–9.04) at baseline and at the time of evaluation had dropped to 1.73 ± 2.11 log10 UI/mL (range <0.78–4.72). The rate of HBV DNA clearance was 54.5% (n = 6). The rate of anti–HBe seroconversion was 77.7% (7/9 HBeAg‐positive patients). The rate of anti‐HBs seroconversion was 9.1% (1/11 patients). There were no significant changes in renal function or hematological parameters.

CONCLUSIONS

This small study demonstrates that entecavir therapy is safe and efficient in HBV‐positive patients with varying degrees of renal dysfunction.
Structural Characterization of Novel ortho‐Lithiated Imines
Authors: Beck John F. , Neshat Abdollah , Schmidt Joseph A. R.
Published: September 2010

ortho‐Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho‐metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho‐lithiated imine precursor is desirable. ortho‐Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4‐methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho‐lithiated imines. NMR spectroscopy and single‐crystal X‐ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6‐R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long‐range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long‐range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p‐character of the carbon–lithium bond.
Motivation to change in adolescents with bulimia nervosa mediates clinical change after treatment
Authors: Castro‐Fornieles Josefina , Bigorra Aitana , Martinez‐Mallen Esteve , Gonzalez Laura , Moreno Elena , Font Elena , Toro Josep
Published: September 2010

Several studies have related motivation to change and treatment response in adult patients with bulimia nervosa but there are no longitudinal studies analysing this relationship in adolescents. The objective was to determine whether motivation to change is related to clinical improvement after treatment in adolescent patients with bulimia nervosa. The Bulimia Nervosa Stages of Change Questionnaire, the Eating Disorders Inventory (EDI‐2) and the Beck Depression Inventory (BDI) were administered at the beginning of treatment to 40 adolescent patients with bulimia nervosa (DSM‐IV) (mean age = 16.2 years). Thirty‐one patients were re‐assessed after 6 months of treatment. The majority of clinical and psychological variables improved significantly at the second evaluation. There were significant correlations between initial motivation to change and improvement in number of binges and the EDI‐2 scales of Bulimia and Interoceptive Awareness. In the stepwise multiple linear regression analysis, which included initial motivation to change and other potential confounding variables such as age, BDI, duration of disorder and body mass index, only motivation to change was selected as a predictor of improvement in number of binges (standardized β coefficient = 0.45; p = 0.012) and of decrease on the Bulimia scale (standardized β coefficient = 0.43; p = 0.029). Regarding improvement in Interoceptive Awareness, only the BDI score was selected as an independent predictor (β coefficient = 0.58; p = 0.002). In conclusion, in adolescent patients receiving treatment for bulimia nervosa, improvement in bulimic symptomatology seems to be especially related to initial motivation to change. Copyright © 2010 John Wiley & Sons, Ltd and Eating Disorders Association.
An aquatic toxicological evaluation of sulfate: The case for considering hardness as a modifying factor in setting water quality guidelines
Authors: Elphick James R , Davies Martin , Gilron Guy , Canaria Edmund C , Lo Bonnie , Bailey Howard C
Published: September 2010

Elevated concentrations of sulfate occur commonly in anthropogenically impacted and natural waters. However, water quality guidelines (WQG) have not been developed in many jurisdictions, and chronic toxicity data are scarce for this anion. A variety of test organisms, including species of invertebrate, fish, algae, moss, and an amphibian, were tested for chronic toxicity to develop a robust dataset that could be used to develop WQGs. As an example of how these data might be used to establish guidelines, calculations were performed using two standard procedures: a species sensitivity distribution (SSD) approach, following methods employed in developing Canadian WQGs, and a safety factor approach, according to procedures typically used in the development of provincial WQGs in British Columbia. The interaction of sulfate toxicity and water hardness was evaluated and incorporated into the calculations, resulting in separate values for soft (10–40 mg/L), moderately hard (80–100 mg/L) and hard water (160–250 mg/L). The resulting values were 129, 644, and 725 mg/L sulfate, respectively, following the SSD approach, and 75, 625, and 675 mg/L sulfate, following the safety factor approach. Environ. Toxicol. Chem. 2011;30:247–253. © 2010 SETAC
The DRBEM solution of incompressible MHD flow equations
Authors: Bozkaya Nuray , Tezer‐Sezgin M.
Published: September 2010

This paper presents a dual reciprocity boundary element method (DRBEM) formulation coupled with an implicit backward difference time integration scheme for the solution of the incompressible magnetohydrodynamic (MHD) flow equations. The governing equations are the coupled system of Navier‐Stokes equations and Maxwell's equations of electromagnetics through Ohm's law. We are concerned with a stream function‐vorticity‐magnetic induction‐current density formulation of the full MHD equations in 2D. The stream function and magnetic induction equations which are poisson‐type, are solved by using DRBEM with the fundamental solution of Laplace equation. In the DRBEM solution of the time‐dependent vorticity and current density equations all the terms apart from the Laplace term are treated as nonhomogeneities. The time derivatives are approximated by an implicit backward difference whereas the convective terms are approximated by radial basis functions. The applications are given for the MHD flow, in a square cavity and in a backward‐facing step. The numerical results for the square cavity problem in the presence of a magnetic field are visualized for several values of Reynolds, Hartmann and magnetic Reynolds numbers. The effect of each parameter is analyzed with the graphs presented in terms of stream function, vorticity, current density and magnetic induction contours. Then, we provide the solution of the step flow problem in terms of velocity field, vorticity, current density and magnetic field for increasing values of Hartmann number. Copyright © 2010 John Wiley & Sons, Ltd.
A review of statistical methods for testing genetic anticipation: looking for an answer in Lynch syndrome
Authors: Boonstra Philip S. , Gruber Stephen B. , Raymond Victoria M. , Huang Shu‐Chen , Timshel Susanne , Nilbert Mef , Mukherjee Bhramar
Published: September 2010

Anticipation, manifested through decreasing age of onset or increased severity in successive generations, has been noted in several genetic diseases. Statistical methods for genetic anticipation range from a simple use of the paired t‐test for age of onset restricted to affected parent‐child pairs to a recently proposed random effects model which includes extended pedigree data and unaffected family members [Larsen et al., 2009]. A naive use of the paired t‐test is biased for the simple reason that age of onset has to be less than the age at ascertainment (interview) for both affected parent and child, and this right truncation effect is more pronounced in children than in parents. In this study, we first review different statistical methods for testing genetic anticipation in affected parent‐child pairs that address the issue of bias due to right truncation. Using affected parent‐child pair data, we compare the paired t‐test with the parametric conditional maximum likelihood approach of Huang and Vieland [1997] and the nonparametric approach of Rabinowitz and Yang [1999] in terms of Type I error and power under various simulation settings and departures from the modeling assumptions. We especially investigate the issue of multiplex ascertainment and its effect on the different methods. We then focus on exploring genetic anticipation in Lynch syndrome and analyze new data on the age of onset in affected parent‐child pairs from families seen at the University of Michigan Cancer Genetics clinic with a mutation in one of the three main mismatch repair (MMR) genes. In contrast to the clinic‐based population, we re‐analyze data on a population‐based Lynch syndrome cohort, derived from the Danish HNPCC‐register. Both datasets indicate evidence of genetic anticipation in Lynch syndrome. We then expand our review to incorporate recently proposed statistical methods that consider family instead of affected pairs as the sampling unit. These prospective censored regression models offer additional flexibility to incorporate unaffected family members, familial correlation and other covariates into the analysis. An expanded dataset from the Danish HNPCC‐register is analyzed by this alternative set of methods. Genet. Epidemiol. 34:756‐768, 2010.© 2010 Wiley‐Liss, Inc.