bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Modular Approach towards the Synthesis of Target‐Specific MRI Contrast Agents
Authors: Verwilst Peter , Eliseeva Svetlana V. , Carron Sophie , Vander Elst Luce , Burtea Carmen , Dehaen Geert , Laurent Sophie , Binnemans Koen , Muller Robert N. , Parac‐Vogt Tatjana N. , De Borggraeve Wim M. 
Published: July 2011

AbstractIn this paper, a modular pathway towards the synthesis of new specific MRI contrast agents and their luminescent analogues is described. Using two azide‐bearing probes, 3β‐deoxycholic acid and cRGDfK(N3), we performed a “click” reaction with an alkyne‐bearing 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) analogue, yielding a possible blood‐pool contrast agent, as well as a contrast agent with a high affinity for cells expressing αvβ3 integrin. The nuclear magnetic relaxation dispersion (NMRD) profiles and human serum albumin (HSA) titration of the contrast agent bearing deoxycholic acid show that this contrast agent interacts with HSA. T1 measurements of Jurkat T cells in the presence of the contrast agent proved the retention of the integrin‐binding property of the RGD‐bearing contrast agent.
Influence of physical pretreatments of sheanuts (Vitellaria paradoxa Gaertn.) on butter quality
Authors: Bup Divine Nde , Kapseu César , Matos Louis , Mabiala Bernard , Mouloungui Zéphirin 
Published: July 2011

AbstractShea butter, usually extracted from kernels of Vitellaria paradoxa Gaertn. by rural women in Sub‐Saharran Africa, has multiple traditional and industrial uses. Traditional processing methods are not standardized and often lead to the production of poor quality butter, which attract low market prices. The aim of this work was to study the different pretreatments locally applied to sheanuts during processing in order to identify those that can affect butter quality. The effect of cooking, soaking as well as drying on the amount of butter extracted and its minor constituents were investigated. All these pretreatments significantly affected oil quality. The effect of soaking of the kernels on improving oil extraction yields (55%) was comparable to that of kernels digested with α‐amylase, acid protease, cellulase/hemicellulase, pectinase, and glucanase enzymes before oil extraction reported in the literature. Drying had a significant negative effect on tocopherol contents of the oil. However, residual amounts of tocopherols in the oil after drying were high enough to suggest that it may still confer anti‐oxidant activities. Soaking, cooking, and drying are important pretreatments involved in the production of shea butter locally that need to be standardized in order to produce better quality butter.Practical applications: In this work, we carried out scientific analysis of methods already used by rural women to process shea fruits into shea butter. This work should be useful for establishing processing conditions for obtaining good quality shea butter.
Lipids, curvature, and nano‐medicine
Authors: Mouritsen Ole G. 
Published: July 2011

AbstractThe physical properties of the lamellar lipid‐bilayer component of biological membranes are controlled by a host of thermodynamic forces leading to overall tensionless bilayers with a conspicuous lateral pressure profile and build‐in curvature‐stress instabilities that may be released locally or globally in terms of morphological changes. In particular, the average molecular shape and the propensity of the different lipid and protein species for forming non‐lamellar and curved structures are a source of structural transitions and control of biological function. The effects of different lipids, sterols, and proteins on membrane structure are discussed and it is shown how one can take advantage of the curvature‐stress modulations brought about by specific molecular agents, such as fatty acids, lysolipids, and other amphiphilic solutes, to construct intelligent drug‐delivery systems that function by enzymatic triggering via curvature.Practical applications: The simple concept of lipid molecular shape and how it impacts on the structure of lipid aggregates, in particular the curvature and curvature stress in lipid bilayers and liposomes, can be exploited to construct liposome‐based drug‐delivery systems, e.g., for use as nano‐medicine in cancer therapy. Non‐lamellar‐forming lysolipids and fatty acids, some of which may be designed to be prodrugs, can be created by phospholipase action in diseased tissues thereby providing for targeted drug release and proliferation of molecular entities with conical shape that break down the permeability barrier of the target cells and may hence enhance efficacy.
Concise Pathway to New Multifunctionalized Constrained Pentacin Derivatives by Means of Two Stereospecific Tandem Reactions
Authors: Coursindel Thibault , Martinez Jean , Parrot Isabelle 
Published: July 2011

AbstractStarting from Boc‐activated diketopiperazines, original bicyclic derivatives of trans‐ and cis‐2‐aminocyclopentanecarboxylic acid were prepared by using two stereospecific tandem reactions. One of them is a tandem transannular rearrangement of activated lactams/alkylation process leading to the stereoselective synthesis of suitably chiral pyrrolidine‐2,4‐diones, allowing subsequent Michael‐initiated ring closure, a simple and concise route to original multifunctionalized alicyclic β‐amino esters.
Polystyrene/graphene composite electrode fabricated by in situ polymerization for capillary electrophoretic determination of bioactive constituents in Herba Houttuyniae
Authors: Lu Yan , Wang Xia , Chen Daofeng , Chen Gang 
Published: July 2011

AbstractA novel graphene/polystyrene composite electrode was developed for the enhanced amperometric detection of CE in this work. The composite electrode was fabricated on the basis of the in situ polymerization of a mixture of graphene and prepolymerized styrene in the bore of a piece of fused‐silica capillary under heat. SEM, XRD, and FTIR offered insights into the nature of the composite. The results indicated that graphenes were well dispersed and embedded throughout the PS matrix to form an interconnected conducting network. The performance of this unique graphene‐based detector has been demonstrated by separating and detecting rutin, isoquercitrin, quercitrin, and chlorogenic acid in Herba Houttuyniae (a traditional Chinese medicine) in combination with CE. The prepared graphene‐based CE detector offered significantly lower detection potential, yielded enhanced signal‐to‐noise characteristics, and exhibited high resistance to surface fouling and enhanced stability. It showed long‐term stability and reproducibility with a relative standard deviation of 3.1% for the peak current (n=15).
Soil seed bank composition and distribution on eroded slopes in the hill‐gully Loess Plateau region (China): influence on natural vegetation colonization
Authors: Wang Ning , Jiao Ju‐Ying , Jia Yan‐Feng , Zhang Xiao‐an 
Published: July 2011

ABSTRACTOn the Chinese Loess Plateau, serious slope and gully erosion have caused a decrease in soil water capacity and fertility, which has resulted in vegetation degradation and a reduction in agricultural productivity. Great efforts have been made to restore vegetation to control soil erosion, but the efficiency of artificial revegetation is not satisfactory. Natural revegetation is an alternative. However, while soil seed banks are an essential source for natural revegetation, their composition and distribution on eroded slopes remains unknown. In addition, whether or not seed loss during soil erosion limits vegetation colonization is also unknown. In this work, soil seed bank composition and distribution were studied in three situations. Specifically, three main microsites were selected as sampling plots: fish‐scale pits, as artificial deposited micro‐topography; under tussocks, as trap microsites; and open areas, as eroded areas. Soil samples were collected at depths of 0–2 cm, 2–5 cm and 5–10 cm. The soil seed bank was identified using germination experiments, and a total of 34 species were identified. The dominant species in the soil seed bank were annual/biennial herbs with an average proportion more than 90% and density reaching 19,000 seeds m‐2. The pioneer species Artemisia scoparia was especially abundant. The dominant later successional species, such as Lespedeza davurica, Artemisia giraldii, Artemisia gmelinii, Stipa bungeana and Bothriochloa ischcemum, were present in the soil at a density that ranged from 38 to 1355 seeds m‐2. Compared with the eroded open areas, the fish‐scale pits retained a higher density of seeds, and the tussocks retained a larger number of species. However, there was no serious reduction of the soil seed bank in the erosion areas. The present study indicates that, on these eroded slopes, the soil seed bank is not the key factor limiting the colonization of natural vegetation. Copyright © 2011 John Wiley & Sons, Ltd.
Expansion rate and geometry of floating vegetation mats on the margins of thermokarst lakes, northern Seward Peninsula, Alaska, USA
Authors: Parsekian Andrew D. , Jones Benjamin M. , Jones Miriam , Grosse Guido , Walter Anthony Katey M. , Slater Lee 
Published: July 2011

ABSTRACTInvestigations on the northern Seward Peninsula in Alaska identified zones of recent (<50 years) permafrost collapse that led to the formation of floating vegetation mats along thermokarst lake margins. The occurrence of floating vegetation mat features indicates rapid degradation of near‐surface permafrost and lake expansion. This paper reports on the recent expansion of these collapse features and their geometry is determined using geophysical and remote sensing measurements. The vegetation mats were observed to have an average thickness of 0.57 m and petrophysical modeling indicated that gas content of 1.5–5% enabled floatation above the lake surface. Furthermore, geophysical investigation provides evidence that the mats form by thaw and subsidence of the underlying permafrost rather than terrestrialization. The temperature of the water below a vegetation mat was observed to remain above freezing late in the winter. Analysis of satellite and aerial imagery indicates that these features have expanded at maximum rates of 1–2 m yr‐1 over a 56 year period. Including the spatial coverage of floating ‘thermokarst mats’ increases estimates of lake area by as much as 4% in some lakes. Copyright © 2011 John Wiley & Sons, Ltd.
Comparative toxicity of eight oil dispersants, Louisiana sweet crude oil (LSC), and chemically dispersed LSC to two aquatic test species
Authors: Hemmer Michael J , Barron Mace G , Greene Richard M 
Published: July 2011

Abstract
The present study describes the acute toxicity of eight commercial oil dispersants, South Louisiana sweet crude oil (LSC), and chemically dispersed LSC. The approach used consistent test methodologies within a single laboratory in assessing the relative acute toxicity of the eight dispersants, including Corexit 9500A, the predominant dispersant applied during the DeepWater Horizon spill in the Gulf of Mexico. Static acute toxicity tests were performed using two Gulf of Mexico estuarine test species, the mysid shrimp (Americamysis bahia) and the inland silversides (Menidia beryllina). Dispersant-only test solutions were prepared with high-energy mixing, whereas water-accommodated fractions of LSC and chemically dispersed LSC were prepared with moderate energy followed by settling and testing of the aqueous phase. The median lethal concentration (LC50) values for the dispersant-only tests were calculated using nominal concentrations, whereas tests conducted with LSC alone and dispersed LSC were based on measured total petroleum hydrocarbon (TPH) concentrations. For all eight dispersants in both test species, the dispersants alone were less toxic (LC50s: 2.9 to &gt;5,600 µl/L) than the dispersant–LSC mixtures (0.4–13 mg TPH/L). Louisiana sweet crude oil alone had generally similar toxicity to A. bahia (LC50: 2.7 mg TPH/L) and M. beryllina (LC50: 3.5 mg TPH/L) as the dispersant–LSC mixtures. The results of the present study indicate that Corexit 9500A had generally similar toxicity to other available dispersants when tested alone but was generally less toxic as a mixture with LSC. Environ. Toxicol. Chem. 2011;30:2244–2252. © 2011 SETAC
Perfluorinated chemicals in surface waters and sediments from northwest Georgia, USA, and their bioaccumulation in Lumbriculus variegatus
Authors: Lasier Peter J , Washington John W , Hassan Sayed M , Jenkins Thomas M 
Published: July 2011

Abstract
Concentrations of perfluorinated chemicals (PFCs) were measured in surface waters and sediments from the Coosa River watershed in northwest Georgia, USA, to examine their distribution downstream of a suspected source. Samples from eight sites were analyzed using liquid chromatography-tandem mass spectrometry. Sediments were also used in 28-d exposures with the aquatic oligochaete, Lumbriculus variegatus, to assess PFC bioaccumulation. Concentrations of PFCs in surface waters and sediments increased significantly below a land-application site (LAS) of municipal/industrial wastewater and were further elevated by unknown sources downstream. Perfluorinated carboxylic acids (PFCAs) with eight or fewer carbons were the most prominent in surface waters. Those with 10 or more carbons predominated sediment and tissue samples. Perfluorooctane sulfonate (PFOS) was the major homolog in contaminated sediments and tissues. This pattern among sediment PFC concentrations was consistent among sites and reflected homolog concentrations emanating from the LAS. Concentrations of PFCs in oligochaete tissues revealed patterns similar to those observed in the respective sediments. The tendency to bioaccumulate increased with PFCA chain length and the presence of the sulfonate moiety. Biota-sediment accumulation factors indicated that short-chain PFCAs with fewer than seven carbons may be environmentally benign alternatives in aquatic ecosystems; however, sulfonates with four to seven carbons may be as likely to bioaccumulate as PFOS. Environ. Toxicol. Chem. 2011;30:2194–2201. © 2011 SETAC
Selenium bioaccumulation and speciation in Chironomus dilutus exposed to water-borne selenate, selenite, or seleno-DL-methionine
Authors: Franz Eric D , Wiramanaden Cheryl I. E , Janz David M , Pickering Ingrid J , Liber Karsten 
Published: July 2011

Abstract
The objective of the present study was to describe the uptake and elimination kinetics of selenium (Se) administered in the forms of selenate, selenite, and selenomethionine (seleno-DL-methionine) in different life stages of the midge Chironomus dilutus, and to determine the relationship between Se bioavailability and Se speciation using X-ray absorption spectroscopy (XAS). Midge larvae exposed to 4.3 µg/L as dissolved selenate for 10 d of had negligible accumulation of Se (indistinguishable from control organisms). However, larvae rapidly accumulated Se over 10 d of exposure to 3.8 and 1.8 µg/L selenite and seleno-DL-methionine (Se-met), respectively. Most Se accumulated by larvae exposed to selenite or Se-met was retained after 10 d of elimination in clean water. When additional midge larvae were exposed to Se until emergence, Se accumulated during the larval stage was largely retained in the adults. Although a strong correlation was found between the adult whole-body Se concentration and the Se concentration in the exuvia after emergence, only a minor loss of Se occurred in the shed exuvia compared with larvae and adult whole-body concentrations. X-ray absorption spectroscopy analysis showed that organic selenides and diselenides, modeled as Se-met and selenocystine, respectively, were the dominant forms of Se in both the larval and adult insect stages. The proportion and concentration of organic selenides (selenomethionine) increased in larvae and adults exposed to Se-met and selenite compared with larvae exposed to selenate, whereas the concentration of diselenides (selenocystine) remained relatively constant for all treatments. Environ. Toxicol. Chem. 2011;30:2292–2299. © 2011 SETAC
Direct numerical simulation of modulation of isotropic turbulence by poly‐dispersed particles
Authors: Kondaraju Sasidhar , Choi Moonho , Xu Xiaofeng , Lee Joon Sang 
Published: July 2011

SUMMARYA direct numerical simulation technique based on two‐way coupling is presented to study a particle‐laden, decaying isotropic turbulent flow. Physical characteristics of turbulence modulation because of the mono‐dispersed (i.e., particles with single Stokes number) and poly‐dispersed particles (i.e., particles with more than one Stokes number) were investigated. A scale dependent effective viscosity that summarizes the aspects of the interaction between the velocity field and particles is defined in the study. Particles of Stokes number (St) 3.2,6.4 and 12.8 were used in performing the simulations. Poly‐dispersed particles were acquired by mixing particles of two different Stokes numbers at a time. As a whole, decay of turbulence because of the poly‐dispersed particles is observed to be larger than that of the decay of turbulence because of the mono‐dispersed particles. Simulations of poly‐dispersed particle indicate nonlinear characteristics in the modification of the temporal evolution of turbulence energy and dissipation. The scale dependent effective viscosity, which correlates with the energy spectrum plot, indicates that the decay of turbulence is mostly observed at the intermediate scales of turbulence. The effective viscosity for the simulations of the poly‐dispersed particles was calculated to be higher than that of the simulations of the mono‐dispersed particles. Copyright © 2011 John Wiley & Sons, Ltd.
A novel peristaltic micropump with low compression ratios
Authors: Tsui Yeng‐Yung , Chang Tso‐Chang 
Published: July 2011

SUMMARYIt is common for peristaltic micropumps to have large compression ratios. In the limit, the chamber of the pump is completely blocked by the membrane to prevent back flow. Different from this kind of pump, a micropump with small compression ratios is proposed in this study. With small oscillation amplitudes the membrane of the pump can reciprocate at high frequencies to improve its pumping flow. Both the multidimensional method and the lumped‐element method are employed for analysis. For this kind of peristaltic micropump the working fluid is allowed to flow freely in the forward and backward directions. Therefore, the operating sequences for the high‐compression ratio type of pumps are not appropriate. It is shown that the theoretical net flow rate is zero for the four‐phase and six‐phase modes of sequence and becomes negative for the three‐phase mode unless regulators, such as the nozzle/diffusers, are incorporated to rectify the flow. However, this pump becomes very attractive by reversing the operating sequence of the three‐phase mode because positive net flow is yielded. It is seen that with the reversed three‐phase mode and the nozzle/diffuser as connecting channels, the pumping effectiveness is greatly enhanced. The pumps with both two chambers and three chambers are under consideration in the study. Copyright ©2011 John Wiley & Sons, Ltd.
Soret and Dufour effects on heat and mass transfer by mixed convection over a vertical surface saturated porous medium with temperature dependent viscosity
Authors: EL‐Kabeir S.M.M. 
Published: July 2011

SUMMARYThe diffusion‐thermo and thermal‐diffusion effects on heat and mass transfer by mixed convection boundary layer flow over a vertical isothermal permeable surface embedded in a porous medium were studied numerically in the presence of chemical reaction with temperature‐dependent viscosity. The governing nonlinear partial differential equations are transformed into a set of coupled ordinary differential equations, which are solved numerically by using Runge–Kutta method with shooting technique. Numerical results are obtained for the velocity, temperature and concentration distributions, and the local skin friction coefficient, local Nusselt number and local Sherwood number for several values of the parameters, namely, the variable viscosity parameter, suction/injection parameter, Darcy number, chemical reaction parameter, and Dufour and Soret numbers. The obtained results are presented graphically and in tabulated form, and the physical aspects of the problem are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Sensitivity of Stresses and Failure Mechanisms in SOFCs to the Mechanical Properties and Geometry of the Constitutive Layers
Authors: Nakajo A. , Van herle J. , Favrat D. 
Published: July 2011

AbstractA model based on the Euler–Bernoulli theory is used to assess the sensitivity of residual stresses in solid oxide fuel cells to the mechanical properties and geometry of the constituents. It considers different cell configurations, characterised by the presence or not of a compensating layer, and a cathode based on either lanthanum strontium manganite (LSM) or lanthanum strontium cobaltite ferrite (LSCF). The implementation of creep in the model provides insights into the parameters that affect the zero‐stress temperature and behaviour during ageing. The amount of irreversible deformation generated in the cell layers after the sintering step depends on the mechanical properties of the layers, type of cell and to some extent, cooling rate. X‐ray diffraction measurements from literature are used to verify the prediction. Depending on the mechanical properties, the stress state in the LSM cathode changes from tensile to compressive with respect to temperature. During combined ageing and thermal cycling, tensile stress might arise in the compatibility layer of LSCF‐based cells, due to the relief of the initial compressive stress at operating temperature. The Weibull analysis provides the assessment of mechanical failure. A simplified approach is used for buckling‐driven delamination, but the propagation of cracks is predicted for unlikely large pre‐existing defects.
Planar Metal‐Supported SOFC with Novel Cermet Anode
Authors: Blennow P. , Hjelm J. , Klemensø T. , Persson Å. H. , Ramousse S. , Mogensen M. 
Published: July 2011

AbstractMetal‐supported solid oxide fuel cells are expected to offer several potential advantages over conventional anode (Ni‐YSZ) supported cells. For example, increased resistance against mechanical and thermal stresses and a reduction in material costs. When Ni‐YSZ based anodes are used in metal supported SOFC, elements from the active anode layer may inter‐diffuse with the metallic support during sintering. This work illustrates how the inter‐diffusion problem can be circumvented by using an alternative anode design based on porous and electronically conducting layers, into which electrocatalytically active materials are infiltrated after sintering. The paper presents the electrochemical performance and durability of the novel planar metal‐supported SOFC design. The electrode performance on symmetrical cells has also been evaluated. The novel cell and anode design shows a promising performance and durability at a broad range of temperatures and is especially suitable for intermediate temperature operation at around 650 °C.
Influence of Compressive Stress on the Water Content of Perfluorosulphonated Membranes: A μ‐Raman Study
Authors: Sutor A. K. , Huguet P. , Morin A. , Gebel G. , Le T. S. , Deabate S. 
Published: July 2011

AbstractThe effect of compressive stress on the local water content of Nafion NRE 212 and Aquivion E79 membranes is studied by confocal μ‐Raman spectroscopy using a specific tightening device. This device aims to mimic the geometry of the bipolar plate flow field of actual fuel cells, i.e. the sequence of channels and ribs. The membrane water content decreases with increasing stress, under the ribs as well as in the channel. The higher the initial water content, the larger the water content decreases with mechanical stress. The extent of water loss depends on the position of the membrane in the device, the applied stress and the hydration history of the membrane.