bluuebunny/crossref_metadata_2025 huggingface dataset:
Étude expérimentale de l’évolution en microcosme du chrome (VI) dans l’eau de mer et de ses effets sur la macrofaune et les bactéries indigènes de la Lagune de Bizerte (Tunisie)
Authors: Ben Khelil Meriem , Ben Said Olfa , Nefzi Rachid , Ben Abdelmalek Jamel , Aïss Patricia
Published: August 2013

La présente étude vise à comparer au laboratoire l’impact biologique du chrome hexavalent (Cr (VI)) présent dans le ciment non déchromé, et celui du chrome présent dans le ciment déchromé en considérant deux échelons trophiques de la lagune de Bizerte : les bactéries indigènes et la macrofaune représentée par la palourde Ruditapes decussatus.

Dans deux types de microcosmes, l’un contenant de l’eau de mer seulement et l’autre contenant de l’eau de mer et du sédiment, la palourde européenne Ruditapes decussatus a été introduite à raison de 20 individus par aquarium. Quatre types d’aquarium ont été mis en place : un témoin (T), un aquarium contaminé par du ciment non déchromé (0,16 mg•L-1 de Cr (VI)), un contaminé par du ciment déchromé (0,05 mg•L-1 de Cr (VI)) et un contaminé par le dichromate de potassium (0,16 mg•L-1 de Cr (VI)). Deux replicats ont été réalisés pour chaque type de microcosme.

La concentration du Cr (VI) dans l’eau a été mesurée par un dosage colorimétrique au début et après 96 heures d’expérimentation. La quantification des bactéries hétérotrophes a été évaluée par la méthode du Nombre le Plus Probable.

Environ 80 % de la quantité du Cr (VI) présente dans le milieu ont été piégés dans les sédiments. Les ciments déchromés et non déchromés ont provoqué 100 % de mortalité chez les palourdes au bout de trois jours. Cependant, il n’a été observé que 40 % de mortalité dans le microcosme contaminé par le K2Cr2O7. Une diminution de la charge bactérienne totale a été observée au niveau des sédiments pour tous les traitements.

On peut dire que la présence du sédiment a entraîné la diminution de la teneur du Cr (VI) dans l’eau et que malgré le déchromage du ciment, les deux types de ciment présentent un effet négatif sur les palourdes et les bactéries indigènes qui est plus marqué pour le ciment non déchromé.
Production et transport des sédiments en suspension dans l’oued Sikkak (Tafna – nord-ouest Algérie)
Authors: Bouanani Abderrazak , Baba-Hamed Kamila , Fandi Wassila
Published: August 2013

L’envasement et le transport solide constituent, par leur importance, un problème majeur en Algérie (dégradation des sols agricoles, alluvionnement des retenues). Les études d’aménagement hydrotechnique butent très souvent sur le problème du manque ou du nombre réduit de données relatives au transport solide. De nombreux chercheurs ont travaillé pour pallier ce problème en mettant au point des modèles spécifiques aux bassins étudiés. Ces derniers servent à combler les lacunes des mesures et à étendre la série existante en fonction du débit liquide souvent mesuré. Cette étude porte sur la quantification du transport solide et du taux d’érosion ainsi que sur la détermination des périodes d’érosion actives et la recherche d’un modèle reliant les débits solides aux débits liquides au niveau de l’oued Sikkak. Sous-bassin de la rivière Tafna, le bassin versant du Sikkak est situé dans le nord-ouest algérien et couvre une surface de 218 km2 où est érigé un barrage d’une capacité de 30 Hm3. Les résultats d’analyse graphique des valeurs instantanées des débits solides en suspension dans l’oued Sikkak à la station d’Aïn Youcef et leurs relations avec les débits liquides (campagnes de prélèvement de 1972 à 1990), ont permis de montrer l’existence de deux périodes d’érosion active. Le flux de matières solides en suspension dans le cours d’eau est très variable d’une année à une autre et la dégradation spécifique moyenne annuelle est estimée à 170 t•km‑2•an‑1 variant de 4 à 745 t•km‑2•an‑1. Ces taux de dégradation restent très modérés par rapport à ceux publiés pour d’autres bassins de l’Algérie et du Maghreb, mais très proches de ceux trouvés pour quelques sous-bassins de la Tafna.
A global change in RNA polymerase II pausing during the Drosophila midblastula transition
Authors: Chen Kai , Johnston Jeff , Shao Wanqing , Meier Samuel , Staber Cynthia , Zeitlinger Julia
Published: August 2013

Massive zygotic transcription begins in many organisms during the midblastula transition when the cell cycle of the dividing egg slows down. A few genes are transcribed before this stage but how this differential activation is accomplished is still an open question. We have performed ChIP-seq experiments on tightly staged Drosophila embryos and show that massive recruitment of RNA polymerase II (Pol II) with widespread pausing occurs de novo during the midblastula transition. However, ∼100 genes are strongly occupied by Pol II before this timepoint and most of them do not show Pol II pausing, consistent with a requirement for rapid transcription during the fast nuclear cycles. This global change in Pol II pausing correlates with distinct core promoter elements and associates a TATA-enriched promoter with the rapid early transcription. This suggests that promoters are differentially used during the zygotic genome activation, presumably because they have distinct dynamic properties.
Robust Results From Climate Model Simulations of Geoengineering
Authors: Kravitz Ben , Robock Alan , Irvine Peter
Published: August 2013

Solar geoengineering has been proposed as a temporary means of alleviating some of the consequences of anthropogenic greenhouse gas emissions. Single‐model studies characterizing the resulting climate effects often used different greenhouse gas concentration profiles and different amounts of geoengineering, making intercomparison difficult. The Geoengineering Model Intercomparison Project (GeoMIP) created a framework of four core simulations, designed to reveal robust features and key uncertainties of climate model responses to geoengineering (B. Kravitz et al., The Geoengineering Model Intercomparison Project (GeoMIP), Atmospheric Science Letters, 12(2), 162–167, doi:10.1002/asl.316, 2011). These experiments simulate solar geoengineering via uniform solar reduction or creation of stratospheric sulfate aerosol layers using state‐of‐the‐art climate models.
Kim Receives 2012 James R. Holton Junior Scientist Award: Citation
Authors: Robock Alan
Published: August 2013

Daehyun Kim received the James R. Holton Junior Scientist Award at the 2012 AGU Fall Meeting, held 3–7 December in San Francisco, Calif. The award recognizes outstanding research contributions by a junior atmospheric scientist within 3 years of his or her Ph.D.
Growth of Sputtered Nanocomposite Alloys on Polymeric Substrates: The Role of the Substrate's Mechanical Hardness
Authors: Zuber Kamil , Downey Elisabeth , Hall Colin , Murphy Peter , Evans Drew
Published: August 2013

Thin multilayer structures consisting of a nanocomposite CrZrx alloy on SiO2 are grown by magnetron sputtering onto hard‐coated polymeric substrates at 350 K. The grain structure and electrical, optical, and mechanical properties of the nanocomposite alloy were investigated using atomic force microscopy, dc conductivity, spectrophotometry, and nano‐scratch testing. Despite the sputtered films being grown in the same deposition run, the grain structure and properties of the thin films were observed to change depending on the siloxane‐based hard‐coat employed. These studies indicate that in addition to the substrate's roughness, the hardness of the siloxane‐based hard‐coat correlates well with the changing properties of the sputtered thin films. To rationalize the influence of the substrate hardness, a hypothesis is proposed where the substrate hardness dissipates a portion of the sputtered material's energy upon impact, leading to changes in its residual energy, thus influencing the material's ability to laterally diffuse on the substrate.
Metal‐Free Direct CH Perfluoroalkylation of Arenes and Heteroarenes Using a Photoredox Organocatalyst
Authors: Cui Lei , Matusaki Yoko , Tada Norihiro , Miura Tsuyoshi , Uno Bunji , Itoh Akichika
Published: August 2013

We report the visible‐light‐induced trifluoromethylation of arenes and heteroarenes using sodium trifluoromethanesulfinate catalyzed by anthraquinone‐2‐carboxylic acid. This reaction is a metal‐free trifluoromethylation of arenes and heteroarenes catalyzed by a photoredox organocatalyst. Perfluoroalkylated arenes were also produced using sodium perfluoroalkylsulfinates.

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Magnetically Separable CuFe2O4 Nanoparticles Catalyzed Ligand‐Free CS Coupling in Water: Access to (E)‐ and (Z)‐Styrenyl‐, Heteroaryl and Sterically Hindered Aryl Sulfides
Authors: Kundu Debasish , Chatterjee Tanmay , Ranu Brindaban C.
Published: August 2013

An efficient coupling of styrenyl, heteroaryl and sterically hindered aryl halides with aryl‐ and heteroarylthiols catalyzed by the bimetallic Cu and Fe nanomaterial, CuFe2O4, in water in the presence of tetrabutylammonium bromide and potassium phosphate (K3PO4) has been achieved without using any ligand. A series of unsymmetrical functionalized (E)‐ and (Z)‐styrenyl aryl, heteroaryl heteroaryl and sterically hindered aryl aryl sulfides has been obtained by this procedure. The compounds are obtained in high yields and excellent stereoselectivity has been observed for styrenyl sulfides. The catalyst can be easily separated by an external magnet and recycled for ten times without any appreciable loss of activity. This procedure provides an easy access to useful and challenging biologically active organosulfides which are difficult to achieve by other methods.

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Silver Triflate‐Palladium Chloride Cooperative Catalysis in a Tandem Reaction for the Synthesis of H‐Pyrazolo[5,1‐a]isoquinolines
Authors: Xiao Qing , Sheng Jie , Ding Qiuping , Wu Jie
Published: August 2013

A tandem reaction of N′‐(2‐alkynylbenzylidene)hydrazone with alcohol in the presence of oxygen co‐catalyzed by silver triflate and palladium chloride under mild conditions is reported, providing H‐pyrazolo[5,1‐a]isoquinolines in good yields. During the transformation, isoquinolinium‐2‐yl amide was the key intermediate via a silver(I)‐catalyzed 6‐endo cyclization of N′‐(2‐alkynylbenzylidene)hydrazone. The presence of a palladium catalyst and molecular oxygen promoted the oxidation of the alcohol to the aldehyde or ketone. Subsequent nucleophilic attack of the in situ generated enolate to isoquinolinium‐2‐yl amide, intramolecular condensation, and aromatization afforded the H‐pyrazolo[5,1‐a]isoquinolines. The easily available starting materials, good substrate generality, mild reaction conditions, and experimental ease should make this method attractive for further library construction.

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Synthesis and Structures of Air‐Stable Binuclear Hafnocene Perfluorobutanesulfonate and Perfluorobenzenesulfonate and their Catalytic Application in CC Bond‐Forming Reactions
Authors: Li Ningbo , Zhang Xiaohong , Xu Xinhua , Chen Yun , Qiu Renhua , Chen Jinyang , Wang Xie , Yin Shuang‐Feng
Published: August 2013

The two air‐stable μ2‐hydroxy‐bridged binuclear hafnocene perfluorobutanesulfonate and perfluorobenzenesulfonate complexes were successfully synthesized. The high catalytic activity and recyclability of these complexes were exemplified for various carbon‐carbon bond formation reactions. Compared with our previously reported hafnocene perfluorooctanesulfonate, these complexes show stronger Lewis acidity and better catalytic activity, and should find broad applications in organic synthesis.

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Carbene Transfer – A New Pathway for Propargylic Esters in Gold Catalysis
Authors: Lauterbach Tobias , Gatzweiler Sabrina , Nösel Pascal , Rudolph Matthias , Rominger Frank , Hashmi A. Stephen K.
Published: August 2013

Gold carbenes generated via 1,2‐migration of a propargylic ester group can be transferred over a tethered alkyne. The use of aromatic backbones leads after a 1,7‐carbene transfer to a benzyl‐stabilized carbene as intermediate. A 1,2‐shift of a methyl group delivers vinyl‐substituted β‐naphthol derivatives as the final products.

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Association of gestational maternal hypothyroxinemia and increased autism risk
Authors: Román Gustavo C. , Ghassabian Akhgar , Bongers‐Schokking Jacoba J. , Jaddoe Vincent W. V. , Hofman Albert , de Rijke Yolanda B. , Verhulst Frank C. , Tiemeier Henning
Published: August 2013

Objective

Transient gestational hypothyroxinemia in rodents induces cortical neuronal migration brain lesions resembling those of autism. We investigated the association between maternal hypothyroxinemia (gestational weeks 6–18) and autistic symptoms in children.

Methods

The mother‐and‐child cohort of the Generation R Study (Rotterdam, the Netherlands) began prenatal enrollment between 2002 and 2006. At a mean gestational age of 13.4 weeks (standard deviation = 1.9, range = 5.9–17.9), maternal thyroid function tests (serum thyrotropin [TSH], free thyroxine [fT4], and thyroid peroxidase [TPO] antibodies) were assessed in 5,100 women. We defined severe maternal hypothyroxinemia as fT4 < 5th percentile with normal TSH. Six years later, parents reported behavioral and emotional symptoms in 4,039 children (79%) using the Pervasive Developmental Problems (PDP) subscale of the Child Behavior Checklist and/or the Social Responsiveness Scale (SRS). We defined a probable autistic child by a PDP score > 98th percentile and SRS score in the top 5% of the sample (n = 81, 2.0%).

Results

Severe maternal hypothyroxinemia (n = 136) was associated with an almost 4‐fold increase in the odds of having a probable autistic child (adjusted odds ratio = 3.89, 95% confidence interval [CI] = 1.83–8.20, p < 0.001). Using PDP scores, children of mothers with severe hypothyroxinemia had higher scores of autistic symptoms by age 6 years (adjusted B = 0.23, 95% CI = 0.03–0.37); SRS results were similar. No risk was found for children of TPO‐antibody–positive mothers (n = 308).

Interpretation

We found a consistent association between severe, early gestation maternal hypothyroxinemia and autistic symptoms in offspring. Findings are concordant with epidemiological, biological, and experimental data on autism. Although these findings cannot establish causality, they open the possibility of preventive interventions. Ann Neurol 2013;74:733–742
Structural, viscoelastic, and vulcanization study of sponge ethylene–propylene–diene monomer composites with various carbon black loadings
Authors: Bashir M. Arshad , Iqbal Nadeem , Shahid Mohammad , Quratulain  , Ahmed Riaz
Published: August 2013

In this article, we report the effect of various carbon nanoparticle concentrations on the structural, curing, tan δ, viscosity variation during vulcanization, thermal, and mechanical characteristics of ethylene–propylene–diene monomer polymer sponge composites. The purpose of this study was to develop high‐strength, foamy‐structure polymer composites with an optimum filler to matrix ratio for advanced engineering applications. We observed that the structural, vulcanization, viscoelastic, and mechanical properties of the fabricated composites were efficiently influenced with the progressive addition of carbon content in the rubber matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39423.
Nanomechanical mapping of glass fiber reinforced polymer composites using atomic force acoustic microscopy
Authors: Zhou Xilong , Fu Ji , Li Yingwei , Li Faxin
Published: August 2013

In this work, a dual‐frequency resonance tracking (DFRT) method was applied on atomic force acoustic microscopy (AFAM) and high‐resolution, quantitative nanomechanical mapping of a glass fiber–reinforced polymer composites (GFRP) was realized. Results show that even using the single‐frequency AFAM, the fiber, and epoxy can give very good contrast in amplitude images. The modulus mapping result on GFRP by DFRT AFAM was compared with that by dynamic nanoindentation, and it is found that DFRT AFAM can map the elastic modulus with high spatial resolution and more reliable results. The interface of GFRP was especially investigated using a 2 μm × 2 μm scanning area. Finite element analysis was implemented to investigate the effect of tip radius and the applied pressing force on the interface measurement using a sharp “interface”. By setting a linear‐modulus‐varied interface with finite width in finite element analysis (FEA), similar comparison between FEA and AFAM experimental results was also implemented. The average interface width is determined to be 476 nm based on the high‐resolution modulus image, indicating that AFAM is a powerful method for nanoscale interface characterization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39800.
Characterization of the bacterioplankton community and its antibiotic resistance genes in the Baltic Sea
Authors: Tiirik Kertu , Nõlvak Hiie , Oopkaup Kristjan , Truu Marika , Preem Jens‐Konrad , Heinaru Ain , Truu Jaak
Published: August 2013

The residues from human environments often contain antibiotics and antibiotic resistance genes (ARGs) that can contaminate natural environments; the clearest consequence of that is the selection of antibiotic‐resistant bacteria. The Baltic Sea is the second largest isolated brackish water reservoir on Earth, serving as a drainage area for people in 14 countries, which differ from one another in antibiotic use and sewage treatment policies. The aim of this study was to characterize the bacterioplankton structure and quantify ARGs (tetA, tetB, tetM, ermB, sul1, blaSHV, and ampC) within the bacterioplankton community of the Baltic Sea. Quantitative polymerase chain reaction was applied to quantify ARGs from four different sampling sites of the Baltic Sea over 2 years, and the bacterial communities were profiled sequencing the V6 region of the 16S rRNA gene on Illumina HiSeq2000. The results revealed that all the resistance genes targeted in the study were detectable from the Baltic Sea bacterioplankton. The percentage of tetA, tetB, tetM, ermB, and sul1 genes in the sea bacterial community varied between 0.0077% and 0.1089%, 0.0003% and 0.0019%, 0.0001% and 0.0105%, 0% and 0.0136%, and 0.0001% and 0.0438%, respectively. The most numerous ARG detected was the tetA gene and this gene also had the highest proportion in the whole microbial community. A strong association between bacterioplankton ARGs’ abundance data and community phylogenetic composition was found, implying that the abundance of most of the studied ARGs in the Baltic Sea is determined by fluctuations in its bacterial community structure.
Adaptation of Dekkera bruxellensis to lignocellulose‐based substrate
Authors: Tiukova Ievgeniia A. , de Barros Pita Will , Sundell David , Haddad Momeni Majid , Horn Svein Jarle , Ståhlberg Jerry , de Morais Marcos Antonio , Passoth Volkmar
Published: August 2013

Adaptation of Dekkera bruxellensis to lignocellulose hydrolysate was investigated. Cells of D. bruxellensis were grown for 72 and 192 H in batch and continuous culture, respectively (adapted cells). Cultivations in semisynthetic medium were run as controls (nonadapted cells). To test the adaptation, cells from these cultures were reinoculated in the lignocellulose medium, and growth and ethanol production characteristics were monitored. Cells adapted to lignocellulose hydrolysate had a shorter lag phase, grew faster, and produced a higher ethanol concentration as compared with nonadapted cells. A stability test showed that after cultivation in rich medium, cells partially lost the adapted phenotype but still showed faster growth and higher ethanol production as compared with nonadapted cells. Because alcohol dehydrogenase genes have been described to be involved in the adaptation to furfural in Saccharomyces cerevisiae, an analogous mechanism of adaptation to lignocelluloses hydrolysate of D. bruxellensis was hypothesized. However, gene expression analysis showed that genes homologous to S. cerevisiae ADH1 were not involved in the adaptation to lignocelluloses hydrolysate in D. bruxellensis.
Utility of noninvasive biomatrices in pharmacokinetic studies
Authors: Raju Kanumuri Siva Rama , Taneja Isha , Singh Sheelendra Pratap , Wahajuddin
Published: August 2013

Blood and plasma are the biomatrices traditionally used for drug monitoring and their pharmacokinetic profiling. Blood is the circulating fluid in contact with all organs and tissues of body and thus is the most representative fluid for measuring systemic drug levels. However, venipuncture suffers from the caveat of being an invasive technique which often makes people reluctant to participate in clinical studies. Thus, there is a need for noninvasive bio‐fluids that are ethically appropriate, cost‐efficient and toxicologically relevant. These alternate bio‐fluids may prove clinically useful as alternatives to plasma/serum in therapeutic drug monitoring, pharmacokinetic and toxicokinetic studies, doping control in sports medicine and to monitor local adverse effects. These may be of particular interest in the case of special population groups such as neonates, children, the elderly, terminally ill patients and pregnant or lactating women, and offer the advantage of circumvention of the demand for specialized personnel for sample collection. This review describes such noninvasive bio‐fluids (saliva, sweat, tears and milk) that have been considered for pharmacokinetic drug analysis, emphasizing their sample preparation, its associated difficulties and their correlation with plasma. Copyright © 2013 John Wiley & Sons, Ltd.
Virtual interactive e‐learning application: An evaluation of the student satisfaction
Authors: Violante Maria Grazia , Vezzetti Enrico
Published: August 2013

In a web‐based learning environment, interactivity has been referred to as the most important element for successful e‐learning. This article presents the production cycle of an interactive medical device, namely a virtual 3D electroencephalogram, and the study conducted to measure the students' satisfaction of the learning application based on Kano's quality model. The web‐based interactive learning application introduces unique elements of interactivity with the learning content, specifically designed to train biomedical engineering students at the use of the medical device. The results of a post‐deployment student survey suggest that the visual and interactive features embedded in the application have the potential to induce positive satisfaction of users. The proposed approach may serve as reference for the correct design of similar learning applications not only in the biomedical engineering context but also outside the realms of engineering sciences. © 2013 Wiley Periodicals, Inc. Comput Appl Eng Educ 23:72–91, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21580
CoLFDImaP: A web‐based tool for teaching of FPGA‐based digital image processing in undergraduate courses
Authors: Garcia I. , Guzmán‐Ramírez E. , Pacheco C.
Published: August 2013

The majority of academic tools for supporting the collaboration between students in Computer Science education have mainly incorporated functionalities for sharing documents and enabling discussions about specific topics. However, nowadays it has never been more imperative for educators to understand how to adapt new functionalities and technologies into real teaching contexts to improve knowledge construction; web‐based real‐time experimentation under a collaborative environment can be a good solution. This article presents a web‐based tool, the Collaborative Lab for FPGA‐based Digital Image Processing, that has been applied as a teaching aid in an undergraduate course using digital image processing and Field Programmable Gate Array (FPGA) technologies. Finally, collaborative experimentation in diverse digital image processing practices is shown. © 2013 Wiley Periodicals, Inc. Comput Appl Eng Educ 23:92–108, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21581
Robust multi‐level partition of unity implicits from triangular meshes
Authors: Li Weitao , Zhou Yuanfeng , Zhang Caiming , Li Xuemei
Published: August 2013

This paper presents a new robust multi‐level partition of unity (MPU) method, which constructs an implicit surface from a triangular mesh via the new error metric between the mesh and the implicit surface. The new error metric employs a weighted function of inner points and vertices of a triangle to fit an implicit surface, which can control the approximation error between the surface and vertices of the triangle. Furthermore, it is applied to the MPU method by utilizing the dual graph of a triangular mesh, and the general quadric implicit surface is used for surface representation. Compared with the MPU method, the new method generates fewer subdivision cells with the same approximation error and performs more steadily especially when given triangular mesh with fewer vertices. Copyright © 2013 John Wiley & Sons, Ltd.
Fast animation of debris flow with mixed adaptive grid refinement
Authors: Wang Changbo , Zhang Qiang , Kong Fanlong , Gao Yusheng
Published: August 2013

Animating debris flow is one of the most challenging tasks in computer graphics, because of its complex dynamic mechanism and the interaction between flows and solids in so large scale region. The difficulty focuses on how to resolve the contradiction between lower computational load and higher request of animating quality. A highly effective method of modeling and animating of debris flow with adaptive grid is presented. First, the debris flow is modeled as Bingham plastic fluid with view‐dependent adaptive grid that is adopted to model the flow volume, and the boundless grids can cover the large scale region of debris flow. Then the mixed grids are built for confluent flows, and the two‐way coupling interaction between flows and environment is considered. After extracting the debris flow surface, adaptive surface tension combining wave particles equation is used to enhance the details and sprays are generated by particles considering the interaction between two fluid volumes. Finally, different dynamic realistic scenes with debris flow are successfully animating at interactive rates. Copyright © 2013 John Wiley & Sons, Ltd.
Effects of FlAsH/Tetracysteine (TC) Tag on PrP Proteolysis and PrPres Formation by TC‐Scanning
Authors: Taguchi Yuzuru , Hohsfield Lindsay A. , Hollister Jason R. , Baron Gerald S.
Published: August 2013

Protein–protein interactions associated with proteolytic processing and aggregation are integral to normal and pathological aspects of prion protein (PrP) biology. Characterization of these interactions requires the identification of amino acid residues involved. The FlAsH/tetracysteine (FlAsH/TC) tag is a small fluorescent tag amenable to insertion at internal sites in proteins. In this study, we used serial FlAsH/TC insertions (TC‐scanning) as a probe to characterize sites of protein–protein interaction between PrP and other molecules. To explore this application in the context of substrate–protease interactions, we analyzed the effect of FlAsH/TC insertions on proteolysis of cellular prion protein (PrPsen) in in vitro reactions and generation of the C1 metabolic fragment of PrPsen in live neuroblastoma cells. The influence of FlAsH/TC insertion was evaluated by TC‐scanning across the cleavage sites of each protease. The results showed that FlAsH/TC inhibited protease cleavage only within limited ranges of the cleavage sites, which varied from about one to six residues in width, depending on the protease, providing an estimate of the PrP residues interacting with each protease. TC‐scanning was also used to probe a different type of protein–protein interaction: the conformational conversion of FlAsH‐PrPsen to the prion disease‐associated isoform, PrPres. PrP constructs with FlAsH/TC insertions at residues 90–96 but not 97–101 were converted to FlAsH‐PrPres, identifying a boundary separating loosely versus compactly folded regions of PrPres. Our observations demonstrate that TC‐scanning with the FlAsH/TC tag can be a versatile method for probing protein–protein interactions and folding processes.
Fundamental Insight into the Substrate‐Dependent Ripening of Monodisperse Clusters
Authors: Fukamori Yves , König Michael , Yoon Bokwon , Wang Bo , Esch Friedrich , Heiz Ueli , Landman Uzi
Published: August 2013

Sintering is one of the major routes for the deactivation of surface‐supported catalytic particles in heterogeneous catalysis. The two mechanisms that are responsible for such coarsening phenomena are Ostwald ripening, in which larger clusters tend to grow at the expense of smaller ones, and Smoluchowski ripening, in which entire clusters diffuse and coalesce. The sintering properties of cluster‐assembled materials can be influenced by tuning the interactions between the particle and the substrate. To explore the fundamental factors that control cluster‐ripening mechanisms, we deposited truly monodisperse Pd clusters onto three different model catalysts: bare Rh(1 1 1), graphene‐Moiré films that were grown on Rh(1 1 1) and Ru(0 0 0 1), and a hexagonal boron‐nitride film that was grown on Rh(1 1 1). The evolution of particle size and density was tracked by high‐resolution scanning tunneling microscopy. The principal microscopic mechanisms that govern the ripening processes on each of these three substrates have been determined from thorough analyses of the cluster heights and size distributions. The ripening mechanisms were related to the distinct cluster‐adsorption and atom‐detachment energies that were obtained from first‐principle calculations. These results elucidate the ripening processes and underlie the formulation of a strategy for optimizing cluster stability against ripening, where both, the binding of the clusters to the surface and that of the individual atoms, must be controlled. Such tuning of the interactions may be achieved through the judicious selection of surfaces with laterally modulated wettability.
Conceptual foundations of diffusion in magnetic resonance
Authors: Koay Cheng Guan , Özarslan Evren
Published: August 2013

A thorough review of the q‐space technique is presented starting from a discussion of Fick's laws. The work presented here is primarily conceptual, theoretical, and hopefully pedagogical. We offered the notion of molecular concentration to unify Fick's laws and diffusion MRI within a coherent conceptual framework. The fundamental relationship between diffusion MRI and Fick's laws is carefully established. The conceptual and theoretical basis of the q‐space technique is investigated from first principles. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 116‐129, 2013.
A slice‐wise latent structure regression method for the analysis of functional magnetic resonance imaging data
Authors: Fayyaz Ahmad , Chaudhary Safee Ullah , Kim Sung‐Ho , Park Hyunwook
Published: August 2013

We introduce a novel slice‐wise latent structure regression (LSR) method for the analysis of functional magnetic resonance imaging (fMRI) data instead of the conventional voxel‐wise generalized least squares (GLS) method. LSR method is designed for application to data sets from slices where fMRI responses (voxels Y* of a slice) are highly correlated with the design matrix X*. Also, we compared the performances of LSR, principal component regression (PCR), and GLS methods in terms of model parameters using experimental fMRI data. The LSR method exhibits an enhanced predictive ability and model coefficients as compared to the PCR and GLS methods. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 130‐139, 2013.
Probing theoretical level effect on fluorine chemical shielding calculations
Authors: Ebrahimi Hossein Pasha , Tafazzoli Mohsen
Published: August 2013

The extensive quantum‐chemical calculations are assessed for prediction of the 19F nuclear magnetic shielding constants. The methods within domain of density functional theory (DFT) and ab initio, Hartree–Fock (HF), and second‐order Møller–Plesset perturbation theory (MP2) are employed for calculation of the 19F chemical shielding constants for a series of 30 small fluorine‐containing molecules. The importance of inclusion of four factors, namely, electron correlation treatment, triple‐ξ valence shell, diffuse function, and polarization function on calculating the fluorine NMR chemical shieldings for a variety of Pople's standard basis sets at gauge invariant atomic orbital (GIAO) and continuous set of gauge transformation (CSGT) conditions are discussed by employing the linear regression analysis. The systematic investigation performed here on the influence of the method, level of theory, and basis set size on the accuracy of 19F chemical shielding demonstrates that the presence of a high level of electron correlation factor in level as well as the polarization function in basis set leads to an accurate wave function to compute the reliable fluorine chemical shielding. The results analysis illustrates that the polarization function has a significant effect on the basis sets to minimize the difference between theoretical and experimental values in several fluorine molecules. An additional comparison of the GIAO and CSGT results is used as a supplementary study to confirm the validity of the results. The basis set dependence of fluorine chemical shielding constants verifies that GIAO provides results that are often more accurate than those that are calculated with CSGT approach at the same basis set size, as expected. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 140‐153, 2013.
Anomalous Property of Ag(BO2)2 Hyperhalogen: Does Spin–Orbit Coupling Matter?
Authors: Chen Hui , Kong Xiang‐Yu , Zheng Weijun , Yao Jiannian , Kandalam Anil K. , Jena Puru
Published: August 2013

Hyperhalogens were recently identified as a new class of highly electronagative species which are composed of metals and superhalogens. In this work, high‐level theoretical calculations and photoelectron spectroscopy experiments are systematically conducted to investigate a series of coinage‐metal‐containing hyperhalogen anions, Cu(BO2)2−, Ag(BO2)2−, and Au(BO2)2−. The vertical electron detachment energy (VDE) of Ag(BO2)2− is anomalously higher than those of Au(BO2)2− and Cu(BO2)2−. In quantitative agreement with the experiment, high‐level ab initio calculations reveal that spin–orbit coupling (SOC) lowers the VDE of Au(BO2)2− significantly. The sizable magnitude of about 0.5 eV of SOC effect on the VDE of Au(BO2)2− demonstrates that SOC plays an important role in the electronic structure of gold hyperhalogens. This study represents a new paradigm for relativistic electronic structure calculations for the one‐electron‐removal process of ionic AuIL2 complexes, which is characterized by a substantial SOC effect.
Adsorption, absorption, versus crystal growth
Authors: Kern Raymond
Published: August 2013

An all‐inclusive review is proposed on the adsorption‐absorption phenomena concerning both equilibrium and growth of crystals. The logical path starts with the relations between the adsorption and growth of pure crystals, continues with the change of the crystal shape due to the surface adsorption of foreign substances (without absorption in the crystal bulk) and terminates with the absorption and crystal growth. Historical aspects are widely illustrated along with the fascinating alternation of observations, experimental efforts and theoretical knowledge.
Detection of silver nanoparticles in cells by flow cytometry using light scatter and far‐red fluorescence
Authors: Zucker R. M. , Daniel K. M. , Massaro E. J. , Karafas S. J. , Degn L. L. , Boyes W. K.
Published: August 2013

The cellular uptake of different sized silver nanoparticles (AgNP) (10, 50, and 75 nm) coated with polyvinylpyrrolidone (PVP) or citrate on a human derived retinal pigment epithelial cell line (ARPE‐19) was detected by flow cytometry following 24‐h incubation of the cells with AgNP. A dose dependent increase of side scatter and far red fluorescence was observed with both PVP and citrate‐coated 50 nm or 75 nm silver particles. Using five different flow cytometers, a far red fluorescence signal in the 700–800 nm range increased as much as 100 times background as a ratio comparing the intensity measurements of treated sample and controls. The citrate‐coated silver nanoparticles (AgNP) revealed slightly more side scatter and far red fluorescence than did the PVP coated silver nanoparticles. This increased far red fluorescence signal was observed with 50 and 75 nm particles, but not with 10 nm particles. Morphological evaluation by dark field microscopy showed silver particles (50 and 75 nm) clumped and concentrated around the nucleus. One possible hypothesis to explain the emission of far red fluorescence from cells incubated with silver nanoparticles is that the silver nanoparticles inside cells agglomerate into small nano clusters that form surface plasmon resonance which interacts with laser light to emit a strong far red fluorescence signal. The results demonstrate that two different parameters (side scatter and far red fluorescence) on standard flow cytometers can be used to detect and observe metallic nanoparticles inside cells. The strength of the far red fluorescence suggests that it may be particularly useful for applications that require high sensitivity. © Published 2013 Wiley‐Periodicals, Inc.
Comparison between self‐report of cannabis use and toxicological detection of THC/THCCOOH in blood and THC in oral fluid in drivers in a roadside survey
Authors: der Linden Trudy Van , Silverans Peter , Verstraete Alain G.
Published: August 2013

The objective of this study was to compare the number of drivers who self‐reported cannabis use by questionnaires to the results of toxicological analysis.

During roadside surveys, 2957 respondents driving a personal car or van completed a questionnaire to report their use of drugs and medicines during the previous two weeks and to indicate the time of their last intake. Cannabis was analyzed in oral fluid by ultra performance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS), in blood by gas chromatography–mass spectrometry (GC‐MS).

Frequencies in the time categories were calculated and compared with toxicological results. Diagnostic values were calculated for the time categories in which positive findings were to be expected (<4 h and <2 4h, respectively for tetrahydrocannabinol (THC) and delta9‐tetrahydrocannabinol (THCCOOH) in blood, <12 h for THC in oral fluid).

Most self‐reported cannabis use was more than 12 h before driving. The sensitivity of the questionnaire was low, while the specificity and accuracy were high. Kappa statistics revealed a fair agreement between self‐report and positive findings for THC in oral fluid and blood and moderate agreement with THCCOOH in blood.

Self‐report largely underestimates driving under the influence of cannabis, particularly recent cannabis use; therefore analysis of biological samples is necessary. Copyright © 2013 John Wiley & Sons, Ltd.
Did southern Western Ghats of peninsular India serve as refugia for its endemic biota during the Cretaceous volcanism?
Authors: Joshi Jahnavi , Karanth Praveen
Published: August 2013

The Western Ghats (WG) of south India, a global biodiversity hotspot, has experienced complex geological history being part of Gondwana landmass and encountered extensive volcanic activity at the end of Cretaceous epoch. It also has a climatically and topographically heterogeneous landscape. Thus, the WG offer a unique setting to explore the influence of ecological and geological processes on the current diversity and distribution of its biota. To this end, three explicit biogeographical scenarios were hypothesized to evaluate the distribution and diversification of wet evergreen species of the WG – (1) southern WG was a refuge for the wet evergreen species during the Cretaceous volcanism, (2) phylogenetic breaks in the species phylogeny would correspond to geographic breaks (i.e., the Palghat gap) in the WG, and (3) species from each of the biogeographic subdivisions within the WG would form distinct clades. These hypotheses were tested on the centipede genus Digitipes from the WG which is known to be an ancient, endemic, and monophyletic group. The Digitipes molecular phylogeny was subjected to divergence date estimation using Bayesian approach, and ancestral areas were reconstructed using parsimony approach for each node in the phylogeny. Ancestral‐area reconstruction suggested 13 independent dispersal events to explain the current distribution of the Digitipes species in the WG. Among these 13 dispersals, two dispersal events were at higher level in the Digitipes phylogeny and were from the southern WG to the central and northern WG independently in the Early Paleocene, after the Cretaceous Volcanism. The remaining 11 dispersal events explained the species’ range expansions of which nine dispersals were from the southern WG to other biogeographic subdivisions in the Eocene‐Miocene in the post‐volcanic periods where species‐level diversifications occurred. Taken together, these results suggest that southern WG might have served as a refuge for Digitipes species during Cretaceous volcanism.
Age‐specific responses to spring temperature in a migratory songbird: older females attempt more broods in warmer springs
Authors: Bulluck L. , Huber S. , Viverette C. , Blem C.
Published: August 2013

Increasing global temperature has led to an interest in plasticity in the timing of annual events; however, little is known about the demographic consequences of changing phenology. Annual reproductive success varies significantly among individuals within a population, and some of that variation has to do with the number of broods attempted by reproducing adults. In birds, female age and the timing of reproduction are often predictors of multiple breeding. We hypothesize that double brooding rates may be affected by spring temperature and that the response may vary with female age. We used a long‐term reproductive data set for a migratory songbird, the prothonotary warbler (Protonotaria citrea) to assess which factors influence (a) an individual female's probability of double brooding and (b) the annual variation in population‐level double brooding rates. We found that older and earlier nesting birds are more likely to double brood, and that there is no evidence for senescence with regard to this trait such that the oldest females were most likely to double brood. Previous experience with double brooding (i.e., whether the female double brooded in the previous year) significantly increased the probability of doing so again. When assessing annual variation in the double brooding rate, we found an interaction between spring temperature and the proportion of older females in the population. Specifically, older females are more likely to double brood in years with warmer springs, but this relationship was not seen for younger females. Previous studies have shown that warmer temperatures lead to earlier and narrower peaks in resources and we hypothesize that these peaks are more available to older and earlier arriving females, enabling them to successfully raise more than one brood in a season. Understanding how different age classes respond to changing environmental conditions will be imperative to managing declining species.
Proline substitution independently enhances H‐2Db complex stabilization and TCR recognition of melanoma‐associated peptides
Authors: Uchtenhagen Hannes , Abualrous Esam T. , Stahl Evi , Allerbring Eva B. , Sluijter Marjolein , Zacharias Martin , Sandalova Tatyana , van Hall Thorbald , Springer Sebastian , Nygren Per‐Åke , Achour Adnane
Published: August 2013

The immunogenicity of H‐2Db (Db) restricted epitopes can be significantly increased by substituting peptide position 3 to a proline (p3P). The p3P modification enhances MHC stability without altering the conformation of the modified epitope allowing for T‐cell cross‐reactivity with the native peptide. The present study reveals how specific interactions between p3P and the highly conserved MHC heavy chain residue Y159 increase the stability of Db in complex with an optimized version of the melanoma‐associated epitope gp10025–33. Furthermore, the p3P modification directly increased the affinity of the Db/gp10025–33‐specific T‐cell receptor (TCR) pMel. Surprisingly, the enhanced TCR binding was independent from the observed increased stability of the optimized Db/gp10025–33 complex and from the interactions formed between p3P and Y159, indicating a direct effect of the p3P modification on TCR recognition.
A literature survey of low‐rank tensor approximation techniques
Authors: Grasedyck Lars , Kressner Daniel , Tobler Christine
Published: August 2013

During the last years, low‐rank tensor approximation has been established as a new tool in scientific computing to address large‐scale linear and multilinear algebra problems, which would be intractable by classical techniques. This survey attempts to give a literature overview of current developments in this area, with an emphasis on function‐related tensors. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A nonstationary extreme value distribution for analysing the cessation of karst spring discharge
Authors: Liu Yan , Hao Yonghong , Fan Yonghui , Wang Tongke , Huo Xueli , Liu Youcun , Yeh Tian‐Chyi J.
Published: August 2013

The effects of climate change and population growth in recent decades are leading us to consider their combined and potentially extreme consequences, particularly regarding hydrological processes, which can be modeled using a generalized extreme value (GEV) distribution. Most of the GEV models were based on a stationary assumption for hydrological processes, in contrast to the nonstationary reality due to climate change and human activities. In this paper, we present the nonstationary generalized extreme value (NSGEV) distribution and use it to investigate the risk of Niangziguan Springs discharge decreasing to zero. Rather than assuming the location, scale, and shape parameters to be constant as one might do for a stationary GEV distribution analysis, the NSGEV approach can reflect the dynamic processes by defining the GEV parameters　as functions of time. Because most of the GEV model is designed to evaluate maxima (e.g. flooding, represented by positive numbers), and spring discharge cessation is a ‛minima’, we deduced an NSGEV model for minima by applying opposite numbers, i.e. negative instead of positive numbers. The results of the model application to Niangziguan Springs showed that the probability of zero discharge at Niangziguan Springs will be 1/80 in 2025, and 1/10 in 2030. After 2025, the rate of decrease in spring discharge will accelerate, and the probability that Niangziguan Springs will cease flowing will dramatically increase. The NSGEV model is a robust method for analysing karst spring discharge. Copyright © 2013 John Wiley & Sons, Ltd.