bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self‐consistent generation of single‐plume state for Enceladus using non‐Newtonian rheology
Authors: Rozel A. , Besserer J. , Golabek G. J. , Kaplan M. , Tackley P. J. 
Published: February 2014

AbstractThe thermal dichotomy of Enceladus suggests an asymmetrical structure in its global heat transfer. So far, most of the models proposed that obtained such a distribution have prescribed an a priori asymmetry, i.e., some anomaly in or below the south polar ice shell. We present here the first set of numerical models of convection that yield a stable single‐plume state for Enceladus without prescribed mechanical asymmetry. Using the convection code StagYY in a 2‐D spherical annulus geometry, we show that a non‐Newtonian ice rheology is sufficient to create a localized, single hot plume surrounded by a conductive ice mantle. We obtain a self‐sustained state in which a region of small angular extent has a sufficiently low viscosity to allow subcritical to weak convection to occur due to the stress‐dependent part of the rheological law. We find that the single‐plume state is very unlikely to remain stable if the rheology is Newtonian, confirming what has been found by previous studies. In a second set of numerical simulations, we also investigate the first‐order effect of tidal heating on the stability of the single‐plume state. Tidal heating reinforces the stability of the single‐plume state if it is generated in the plume itself. Lastly, we show that the likelihood of a stable single‐plume state does not depend on the thickness of the ice shell.
The value of satellite‐derived snow cover images for calibrating a hydrological model in snow‐dominated catchments in Central Asia
Authors: Duethmann Doris , Peters Juliane , Blume Theresa , Vorogushyn Sergiy , Güntner Andreas 
Published: February 2014

AbstractIncluding satellite‐derived snow cover data for hydrologic model calibration can be a good way to improve model internal consistency. This study applied a multiobjective genetic algorithm to characterize the trade‐off curve between model performance in terms of discharge and snow cover area (SCA). Using a Monte Carlo‐based approach, we further investigated the additional information content of an increasing number of SCA scenes used in the calibration period. The study was performed in six snowmelt‐dominated headwater catchments of the Karadarya Basin in Kyrgyzstan, Central Asia, using the hydrological model WASA and snow cover data from four melt seasons retrieved from AVHRR (Advanced Very High Resolution Radiometer). We generally found only small trade‐offs between good simulations with respect to discharge and SCA, but good model performance with respect to discharge did not exclude low performance in terms of SCA. On average, the snow cover error in the validation period could be reduced by very few images in the calibration period. Increasing the number of images resulted in only small further improvements. However, using only a small number of images involves the risk that these particular images cause the selection of parameter sets which are not representative for the catchment. It is therefore advisable to use a larger number of images. In this study, it was necessary to include at least 10–16 images.
A stochastic model of streamflow for urbanized basins
Authors: Mejía Alfonso , Daly Edoardo , Rossel Florian , Jovanovic Tijana , Gironás Jorge 
Published: February 2014

AbstractGiven the critical role of the streamflow regime for instream, riparian, and floodplain ecosystem sustainability, modeling the long‐term effect of urbanization on streamflow is important to predict possible changes in stream ecosystems. Since flow duration curves are largely used to characterize the streamflow regime and define indices for stream ecosystem health, we present two stochastic models, with different levels of complexity, that link the key physical features of urbanized basins with rainfall variability to determine the resulting flow duration curves. The two models are tested against 11 basins with various degrees of urban development, characterized by the percentage of impervious areas in the basin. Results show that the more complex model needs to be used to reproduce accurately the entire flow duration curve. The analysis performed suggests that the transformation of green (i.e., water used in evapotranspiration) to blue (i.e., streamflow) water in urbanized basins is an important long‐term source of ecohydrological alteration. The modeling scheme also provides useful links between rainfall variability, urbanization levels, and some streamflow indices of high and low flows.
The Role of Memory Distrust in Cases of Internalised False Confession
Authors: Gudjonsson Gisli Hannes , Sigurdsson Jon Fridrik , Sigurdardottir Arndis Soffia , Steinthorsson Haraldur , Sigurdardottir Valgerdur Maria 
Published: February 2014

AbstractThis paper reviews the literature on the role of ‘memory distrust’ in cases of internalised false confessions and provides a heuristic model for understanding the antecedents and mechanism involved. It also provides an in‐depth analysis of two real life cases of ‘suspected’ murders involving six convicted persons, five of whom showed evidence of profound memory distrust regarding the alleged offences. The key factors were coercive interviewing, lengthy solitary confinement, contamination, psychological vulnerabilities (both state and trait) and lack of independent support during questioning. The vulnerabilities in such cases typically involve a combination of cognitive (memory flaws, lack of confidence in memory and failure to invoke distinctiveness heuristic), personality (suggestibility and compliance), health problems and motivational (desire and willingness to assist the police) factors. The two cases suggest that the process of internalised false confessions may be conceptualised in terms of five sequential steps: a trigger, plausibility, acceptance, reconstruction and resolution. Copyright © 2014 John Wiley & Sons, Ltd.
FeII‐Spincrossover‐Komplexe in ultradünnen Filmen: elektronische Struktur und Spinschaltung durch sichtbares und Vakuum‐UV‐Licht
Authors: Ludwig E. , Naggert H. , Kalläne M. , Rohlf S. , Kröger E. , Bannwarth A. , Quer A. , Rossnagel K. , Kipp L. , Tuczek F. 
Published: February 2014

AbstractDie elektronische Struktur des FeII‐Spincrossover‐Komplexes [Fe(H2bpz)2(phen)], deponiert als ultradünner Film auf Au(111), wird mithilfe von UV‐Photoelektronenspektroskopie (UPS) im High‐Spin‐ und im Low‐Spin‐Zustand bestimmt. Dies ermöglicht es auch, den thermischen sowie den photoinduzierten Spinübergang in diesem System zu verfolgen. Der Komplex wird ebenfalls durch Bestrahlung mit Vakuum‐UV‐Licht in den metastabilen High‐Spin‐Zustand überführt. Relaxationsraten nach Photoanregung werden als Funktion der Temperatur bestimmt. Sie zeigen einen Übergang von thermisch aktiviertem zu Tunnelverhalten und sind zwei Größenordnungen höher als im Volumenmaterial.
Tunable Oxygen Activation for Catalytic Organic Oxidation: Schottky Junction versus Plasmonic Effects
Authors: Long Ran , Mao Keke , Gong Ming , Zhou Shan , Hu Jiahua , Zhi Min , You Yang , Bai Song , Jiang Jun , Zhang Qun , Wu Xiaojun , Xiong Yujie 
Published: February 2014

AbstractThe charge state of the Pd surface is a critical parameter in terms of the ability of Pd nanocrystals to activate O2 to generate a species that behaves like singlet O2 both chemically and physically. Motivated by this finding, we designed a metal–semiconductor hybrid system in which Pd nanocrystals enclosed by {100} facets are deposited on TiO2 supports. Driven by the Schottky junction, the TiO2 supports can provide electrons for metal catalysts under illumination by appropriate light. Further examination by ultrafast spectroscopy revealed that the plasmonics of Pd may force a large number of electrons to undergo reverse migration from Pd to the conduction band of TiO2 under strong illumination, thus lowering the electron density of the Pd surface as a side effect. We were therefore able to rationally tailor the charge state of the metal surface and thus modulate the function of Pd nanocrystals in O2 activation and organic oxidation reactions by simply altering the intensity of light shed on Pd–TiO2 hybrid structures.
CH Bond Arylation in the Synthesis of Aryltetralin Lignans: A Short Total Synthesis of Podophyllotoxin
Authors: Ting Chi P. , Maimone Thomas J. 
Published: February 2014

AbstractA short total synthesis of podophyllotoxin, the prototypical aryltetralin lignan natural product, is reported. Key to the success of this synthetic pathway is a Pd‐catalyzed C(sp3)–H arylation reaction enabled by a conformational biasing element to promote C–C reductive elimination over an alternative CN bond‐forming pathway. This strategy allows for access to the natural product in five steps from commercially available bromopiperonal, and sheds light on subtle conformational effects governing reductive elimination pathways from high‐valent palladium centers.
New Generation of Biocatalysts for Organic Synthesis
Authors: Nestl Bettina M. , Hammer Stephan C. , Nebel Bernd A. , Hauer Bernhard 
Published: February 2014

AbstractThe use of enzymes as catalysts for the preparation of novel compounds has received steadily increasing attention over the past few years. High demands are placed on the identification of new biocatalysts for organic synthesis. The catalysis of more ambitious reactions reflects the high expectations of this field of research. Enzymes play an increasingly important role as biocatalysts in the synthesis of key intermediates for the pharmaceutical and chemical industry, and new enzymatic technologies and processes have been established. Enzymes are an important part of the spectrum of catalysts available for synthetic chemistry. The advantages and applications of the most recent and attractive biocatalysts—reductases, transaminases, ammonia lyases, epoxide hydrolases, and dehalogenases—will be discussed herein and exemplified by the syntheses of interesting compounds.
Toward a Symphony of Reactivity: Cascades Involving Catalysis and Sigmatropic Rearrangements
Authors: Jones Amanda C. , May Jeremy A. , Sarpong Richmond , Stoltz Brian M. 
Published: February 2014

AbstractCatalysis and synthesis are intimately linked in modern organic chemistry. The synthesis of complex molecules is an ever evolving area of science. In many regards, the inherent beauty associated with a synthetic sequence can be linked to a certain combination of the creativity with which a sequence is designed and the overall efficiency with which the ultimate process is performed. In synthesis, as in other endeavors, beauty is very much in the eyes of the beholder. It is with this in mind that we will attempt to review an area of synthesis that has fascinated us and that we find extraordinarily beautiful, namely the combination of catalysis and sigmatropic rearrangements in consecutive and cascade sequences.
Sometimes the assessment of beauty is nearly unanimous. The first four notes of Beethoven’s 5th Symphony (Symphony No.5 in C minor, Op.67) represent perhaps the most well‐known and popular motif in classical music. The orchestral score is shown in the background of the cover graphic. Accessed March 20, 2013 from http://imslp.org/wiki/Symphony_No.5,_Op.67_%28Beethoven,_Ludwig_van%29.
Metal‐Free Hydrogenation of Unsaturated Hydrocarbons Employing Molecular Hydrogen
Authors: Paradies Jan 
Published: February 2014

AbstractThe metal‐free activation of hydrogen by frustrated Lewis pairs (FLPs) is a valuable method for the hydrogenation of polarized unsaturated molecules ranging from imines, enamines, and silyl enol ethers to heterocycles. However, one of the most important applications of hydrogenation technology is the conversion of unsaturated hydrocarbons into alkanes or alkenes. Despite the fast development of the FLP chemistry, such reactions proved as highly challenging. This Minireview provides an overview of the basic concepts of FLP chemistry, the challenge in the hydrogenation of unsaturated hydrocarbons, and first solutions to this central transformation.
Heterologous Reconstitution of Ikarugamycin Biosynthesis in E. coli
Authors: Antosch Janine , Schaefers Françoise , Gulder Tobias A. M. 
Published: February 2014

AbstractPolycyclic tetramate macrolactams (PTMs) are a family of biomedically promising natural products with challenging molecular frameworks. Despite these interesting properties, so far only relatively little is known about the biosynthetic origin of PTMs, in particular concerning the mechanism by which their ring systems are formed. Herein we present the first insights into these processes by using the biosynthesis of ikarugamycin as an example. This has been facilitated by the first heterologous expression of a PTM biosynthetic gene cluster in Escherichia coli. With this approach it will not only become possible to mechanistically investigate already known PTM biosynthetic pathways in more detail in the future, but also to interrogate cryptic PTM biosynthetic pathways chemically and biochemically.
Significantly improving electro‐activated shape recovery performance of shape memory nanocomposite by self‐assembled carbon nanofiber and hexagonal boron nitride
Authors: Lu Haibao , Lei Ming , Leng Jinsong 
Published: February 2014

ABSTRACTThis study presents two effective approaches to significantly improve the electro‐thermal properties and electro‐activated shape recovery performance of shape memory polymer (SMP) nanocomposites that are incorporated with carbon nanofibers (CNFs) and hexagonal boron nitrides (h‐BNs), and show Joule heating triggered shape recovery. CNFs were self‐assembled and deposited into buckypaper form to significantly improve the electrical properties of SMP and achieve the shape memory effect induced by electricity. The h‐BNs were either blended into or self‐assembled onto CNF buckypaper to significantly improve the thermally conductive properties and electro‐thermal performance of SMPs. Furthermore, the shape recovery behavior and temperature profile during the electrical actuation of the SMP nanocomposites were monitored and characterized. It was found that a unique synergistic effect of CNFs and h‐BNs was presented to facilitate the heat transfer and accelerate the electro‐activated shape recovery behavior of the SMP nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40506.
Functionalized KIT‐6/Terpolyimide composites with ultra‐low dielectric constant
Authors: Purushothaman Revathi , Palanichamy Muthiapillai , Mohammed Bilal I. 
Published: February 2014

ABSTRACTPolyimides with low dielectric constants are important raw materials for the fabrication of flexible printed circuit boards and other microelectronic applications. As creation of voids in polyimide matrix could decrease dielectric constant, in this study mesoporous KIT‐6, synthesized hydrothermally, was functionalized with 3‐aminopropyltriethoxysilane (APTS) and mixed with 4,4′‐oxydianiline (ODA) in the synthesis of terpoly(amic acid) using 3,3′,4,4′‐biphenyldianhydride (BPDA), 3,3′,4,4′‐oxydiphthalic dianhydride (ODPA) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and subsequently stage‐cured to obtain APTS‐KIT‐6/Terpolyimide composites (APTS‐KIT‐6/TPI). The asymmetric and symmetric vibrations of imide OCNCO groups of APTS‐KIT‐6/TPI composites showed their peaks at 1772 and 1713 cm−1. The dielectric constant decreased with the increase in KIT‐6 loading from 2 to 4%, but increased at higher loadings, and at 4% loading it was 1.42. Its tensile strength (103 MPa), tensile modulus (2.5 GPa), and percentage elongation (8.2) and high thermal stability (>540°C) were also adequate for application in microelectronics such as flexible printed circuits. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40508.
Comparison of modification of a bacterial uricase with N‐hydroxysuccinimide esters of succinate and carbonate of monomethoxyl poly(ethylene glycol)
Authors: Zhang Chun , Yang Xiaolan , Gao Ang , Hu Xiaolei , Pu Jun , Liu Hongbo , Feng Juan , Liao Juan , Li Yuanli , Liao Fei 
Published: February 2014

AbstractUricase after modification with monomethoxy poly(ethylene glycol) (mPEG) is currently the sole agent to treat refractory gout. For formulating Bacillus fastidious uricase, succinimidyl carbonate of mPEG‐5000 (SC‐mPEG5k) and succinimidyl succinate of mPEG‐5000 (SS‐mPEG5k) were compared. SC‐mPEG5k possessed higher purity, comparable reaction rate constant with glycine but lower hydrolysis rate, and stronger effectiveness to modify amino groups. The uricase possessed two types of amino groups bearing a 25‐fold difference in reactivity with SC‐mPEG5k or SS‐mPEG5k at pH 9.2. Oxonate and xanthine concentration‐dependently protected the bacterial uricase from inactivation during PEGylation. With SC‐mPEG5k at a molar ratio of 200 to uricase subunits and oxonate of 50 µM, the PEGylated uricase (1) retained about 73% of the original activity, (2) displayed about 10% reactivity to rabbit anti‐sera recognizing the native uricase, (3) elicited IgG in rats accounting for about 5% of that by the native uricase, (4) exhibited circulation half‐life time of about 25 H in cock plasma in vivo, and (5) concurrently maintained uric acid at lowered levels for over 20 H. Hence, PEGylation with SC‐mPEG under the protection of a competitive inhibitor was a practical approach to formulation of the bacterial uricase; protection of enzymes by competitive inhibitors during PEGylation may have universal significance.
Rare nasal cleft in a patient with holoprosencephaly due to a mutation in the ZIC2 gene
Authors: Savastano Clarice Pagani , Bernardi Pricila , Seuánez Hector N. , Moreira Miguel Ângelo Martins , Orioli Iêda Maria 
Published: February 2014

BACKGROUNDHoloprosencephaly (HPE) is a spectrum of midline malformations of the prosencephalon generally reflected in a continuum of midline facial anomalies. Patients with mutation in the ZIC2 gene usually present a normal or mildly dysmorphic face associated with a severe brain malformation. Here we present a rare unilateral nasal cleft (Tessier cleft n. 1) with holoprosencephaly in a patient with a ZIC2 mutation.CASEThe male newborn presented with alobar HPE, microcephaly, ocular hypertelorism, upslanting palpebral fissures, a bulky nose with a left paramedian alar cleft. Mutational screening for HPE genes revealed the occurrence of a frameshift mutation in the ZIC2 gene. The mutation was inherited from the father who presented only mild ocular hypotelorism but had an affected child with HPE from his first marriage.CONCLUSIONThe occurrence of oral clefts is common in patients with HPE, but unusual in patients with mutation in the ZIC2 gene. To our knowledge, clefts of the nasal alae have been reported only once or twice in patients with ZIC2 mutations. In documented patients from the literature, only 2% of individuals with described pathogenic mutations in the ZIC2 gene (3/171) presented facial clefts, one of them a nasal cleft, while common oral clefts were observed in 27% of individuals (7/26) described with nonpathogenic ZIC2 mutations or presenting a concomitant mutation in another HPE gene. When compared with the general population, nasal clefts are common in ZIC2 mutations and these mutations must be searched for in undiagnosed cases. Birth Defects Research (Part A) 100:300–306, 2014. © 2014 Wiley Periodicals, Inc.
Ho3+‐doped strontium–aluminium–bismuth–borate glasses for green light emission
Authors: Rajesh D. , Dhamodhara Naidu M. , Ratnakaram Y. C. , Balakrishna A. 
Published: February 2014

ABSTRACTStrontium–aluminium–bismuth–borate glasses (SAlBiB) doped with different concentrations of Ho3+ were prepared using conventional melt quenching technique and their structural and optical properties investigated. X‐ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd–Ofelt (J‐O) theory was applied to evaluate J‐O intensity parameters, Ωλ (λ = 2, 4 and 6). Using J‐O intensity parameters, radiative properties such as spontaneous transition probabilities (AR), branching ratios (βR) and radiative lifetimes (τR) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, 5S2(5F4)→5I8 was observed. Emission peak positions (λP), effective bandwidths (Δλeff) and stimulated emission cross‐sections (σp) were calculated for the observed emission transitions, 5F3→5I8, 5S2(5F4)→5I8 and 5F5→5I8 of Ho3+ in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho3+ has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd.
Directed evolution of a cellodextrin transporter for improved biofuel production under anaerobic conditions in Saccharomyces cerevisiae
Authors: Lian Jiazhang , Li Yanglin , HamediRad Mohammad , Zhao Huimin 
Published: February 2014

ABSTRACTIntroduction of a cellobiose utilization pathway consisting of a cellodextrin transporter and a β‐glucosidase into Saccharomyces cerevisiae enables co‐fermentation of cellobiose and xylose. Cellodextrin transporter 1 (CDT1) from Neurospora crassa has been established as an effective transporter for the engineered cellobiose utilization pathways. However, cellodextrin transporter 2 (CDT2) from the same species is a facilitator and has the potential to be more efficient than CDT1 under anaerobic conditions due to its energetic benefits. Currently, CDT2 has a very low activity and is considered rate‐limiting in cellobiose fermentation. Here, we report the directed evolution of CDT2 with an increased cellobiose uptake activity, which results in improved cellobiose fermentation under anaerobic conditions. After three rounds of directed evolution, the cellobiose uptake activity of CDT2 was increased by 2.2‐fold, which resulted from both increased specific activity and transporter expression level. Using high cell density fermentation under anaerobic conditions, the evolved mutant conferred 4.0‐ and 4.4‐fold increase in the cellobiose consumption rate and ethanol productivity, respectively. In addition, although the cellobiose uptake activity was still lower than that of CDT1, the engineered CDT2 showed significantly improved cellobiose consumption and ethanol production under anaerobic conditions, representing the energetic benefits of a sugar facilitator for anaerobic cellobiose fermentation. This study demonstrated that anaerobic biofuel production could be significantly improved via directed evolution of a sugar transporter protein in yeast. Biotechnol. Bioeng. 2014;111: 1521–1531. © 2014 Wiley Periodicals, Inc.
Evaluation of a kinetic model for computer simulation of growth and fermentation by Scheffersomyces (Pichia) stipitis fed D‐xylose
Authors: Slininger P. J. , Dien B. S. , Lomont J. M. , Bothast R. J. , Ladisch M. R. , Okos M. R. 
Published: February 2014

ABSTRACTScheffersomyces (formerly Pichia) stipitis is a potential biocatalyst for converting lignocelluloses to ethanol because the yeast natively ferments xylose. An unstructured kinetic model based upon a system of linear differential equations has been formulated that describes growth and ethanol production as functions of ethanol, oxygen, and xylose concentrations for both growth and fermentation stages. The model was validated for various growth conditions including batch, cell recycle, batch with in situ ethanol removal and fed‐batch. The model provides a summary of basic physiological yeast properties and is an important tool for simulating and optimizing various culture conditions and evaluating various bioreactor designs for ethanol production. Biotechnol. Bioeng. 2014;111: 1532–1540. © 2014 Wiley Periodicals, Inc.