bluuebunny/crossref_metadata_2025_split huggingface dataset:
TEC retrieval from spaceborne SAR data and its applications
Authors: Wang Cheng , Zhang Min , Xu Zheng‐Wen , Zhao Hai‐Sheng 
Published: October 2014

AbstractIt is well known that the spaceborne synthetic aperture radar (SAR) at VHF‐UHF band can be seriously affected by the ionosphere. Thus, the geophysical information of the ionosphere will be embedded in the low‐frequency SAR echoes after they transverse the ionosphere. Correspondingly, the total electron content (TEC), a typical ionospheric information parameter, can be retrieved from the spaceborne SAR data. However, the existing dual‐band techniques for TEC retrieval usually do not include consideration of multiple scattering effects caused by turbulent ionosphere, which plays an important role in the total path delay of signal under the strong fluctuation regimes. The result of TEC retrieval is therefore inaccurate and not applicable. Aiming at this issue, first, this paper analyzes the effects of regular background and the irregularity of electron density on SAR at L‐band, and the theoretical formulation is given. Then, a triband path delay technique of TEC retrieval based on the SAR data is proposed. By using three path delays corresponding to three specific frequencies within the signal bandwidth, this technique can remove the errors of multiple scattering due to the irregularity, and a high accuracy resolution of TEC value therefore can be obtained. Meanwhile, the sensitivity of this technique is analyzed. Finally, compared with traditional dual‐band technique, the numerical simulations show that the correction of SAR imaging based on triband technique is improved significantly. In addition, the resolution of reconstruction imaging using computerized ionospheric tomography performs significantly better based on the triband technique.
Comparing drag partition schemes over a herbaceous Sahelian rangeland
Authors: Pierre C. , Bergametti G. , Marticorena B. , Kergoat L. , Mougin E. , Hiernaux P. 
Published: October 2014

AbstractModeling of dust emissions from the surface remains complex, especially in semiarid regions where vegetation must be accounted for because of its potentially important protective effect. Protection is directly linked to the fraction of the soil surface covered by vegetation, but it is also driven by the interaction of vegetation elements with the wind field. The sensitivity of simulated dust emissions to various drag partition schemes—mainly those proposed by Raupach (1992), Marticorena and Bergametti (1995), and Okin (2008)—is evaluated for a typical Sahelian rangeland, covered by a seasonal grass layer, over a complete vegetation cycle. The application of these schemes requires a fine characterization of the vegetation cover; field measurements from an ecological survey are used to derive the geometric dimensions of the grass patches. Models are run with meteorological forcing from automatic weather stations. As a result, the impacts of soil moisture and grass cover are estimated over April to September. Soil moisture inhibits dust emissions by 27% in mass. The different drag partition schemes exhibit distinctive limitations, mostly due to the properties of the Sahelian grass cover, which is composed of large and low patches of short grass, with a strong seasonal dynamics. However, the drag partition schemes result in remarkably coherent estimations of dust emissions. When soil moisture is taken into account, vegetation reduces the total vertical mass fluxes by 6 to 26% of the emissions of a bare soil, depending on the drag partition scheme.
Using observations and a distributed hydrologic model to explore runoff thresholds linked with mesquite encroachment in the Sonoran Desert
Authors: Pierini Nicole A. , Vivoni Enrique R. , Robles‐Morua Agustin , Scott Russell L. , Nearing Mark A. 
Published: October 2014

AbstractWoody plant encroachment is a world wide phenomenon with implications on the hydrologic cycle at the catchment scale that are not well understood. In this study, we use observations from two small semiarid watersheds in southern Arizona that have been encroached by the velvet mesquite tree and apply a distributed hydrologic model to explore runoff threshold processes experienced during the North American monsoon. The paired watersheds have similar soil and meteorological conditions, but vary considerably in terms of vegetation cover (mesquite, grass, bare soil) and their proportions with one basin having undergone mesquite removal in 1974. Long‐term observations from the watersheds exhibit changes in runoff production over time, such that the watershed with more woody plants currently has less runoff for small rainfall events, more runoff for larger events, and a larger runoff ratio during the study periods (summers 2011 and 2012). To explain this observation, we first test the distributed model, parameterized with high‐resolution (1 m) terrain and vegetation distributions, against continuous data from an environmental sensor network, including an eddy covariance tower, soil moisture, and temperature profiles in different vegetation types, and runoff observations. We find good agreement between the model and observations for simultaneous water and energy states and fluxes over a range of measurement scales. We then identify that the areal fraction of grass (bare soil) cover determines the runoff response for small (large) rainfall events due to the dominant controls of antecedent wetness (hydraulic conductivity). These model‐derived mechanisms explain how woody plants have differential effects on runoff in semiarid basins depending on precipitation event sizes.
B(C6F5)3‐katalysierte Hydrierung von Oximethern ohne Spaltung der N‐O‐Bindung
Authors: Mohr Jens , Oestreich Martin 
Published: October 2014

AbstractDie Hydrierung von Oximen und Oximethern geht normalerweise mit der Spaltung der N‐O‐Bindung einher und setzt daher Amine und eben nicht Hydroxylamine frei. Die Bor‐Lewis‐Säure B(C6F5)3 katalysiert die chemoselektive Hydrierung von Oximethern bei erhöhter oder sogar Raumtemperatur unter 100 bar Wasserstoffdruck. Die Verwendung der Triisopropylsilylgruppe als Schutzgruppe erlaubt eine mühelose Freisetzung der Hydroxylamine.
Substrate‐Selective Catalysis
Authors: Lindbäck Emil , Dawaigher Sami , Wärnmark Kenneth 
Published: October 2014

AbstractSubstrate selectivity is an important output function for the validation of different enzyme models, catalytic cavity compounds, and reaction mechanisms as demonstrated in this review. In contrast to stereo‐, regio‐, and chemoselective catalysis, the field of substrate‐selective catalysis is under‐researched and has to date generated only a few, but important, industrial applications. This review points out the broad spectrum of different reaction types that have been investigated in substrate‐selective catalysis. The present review is the first one covering substrate‐selective catalysis and deals with reactions in which the substrates involved have the same reacting functionality and the catalysts is used in catalytic or in stoichiometric amounts. The review covers real substrate‐selective catalysis, thus only including cases in which substrate‐selective catalysis has been observed in competition between substrates.
Fe2O3–TiO2 Nanocomposites for Enhanced Charge Separation and Photocatalytic Activity
Authors: Moniz Savio J. A. , Shevlin Stephen A. , An Xiaoqiang , Guo Zheng‐Xiao , Tang Junwang 
Published: October 2014

AbstractPhotocatalysis provides a cost effective method for both renewable energy synthesis and environmental purification. Photocatalytic activity is dominated by the material design strategy and synthesis methods. Here, for the first time, we report very mild and effective photo‐deposition procedures for the synthesis of novel Fe2O3–TiO2 nanocomposites. Their photocatalytic activities have been found to be dramatically enhanced for both contaminant decomposition and photoelectrochemical water splitting. When used to decompose a model contaminant herbicide, 2,4‐dichlorophenoxyacetic acid (2,4‐D), monitored by both UV/Vis and total organic carbon (TOC) analysis, 10 % Fe–TiO2–H2O displayed a remarkable enhancement of more than 200 % in the kinetics of complete mineralisation in comparison to the commercial material P25 TiO2 photocatalyst. Furthermore, the photocurrent is nearly double that of P25. The mechanism for this improvement in activity was determined using density functional theory (DFT) and photoluminescence. These approaches ultimately reveal that the photoelectron transfer is from TiO2 to Fe2O3. This favours O2 reduction which is the rate‐determining step in photocatalytic environmental purification. This in situ charge separation also allows for facile migration of holes from the valence band of TiO2 to the surface for the expected oxidation reactions, leading to higher photocurrent and better photocatalytic activity.
Cyclooctane Metathesis Catalyzed by Silica‐Supported Tungsten Pentamethyl [(SiO)W(Me)5]: Distribution of Macrocyclic Alkanes
Authors: Riache Nassima , Callens Emmanuel , Samantaray Manoja K. , Kharbatia Najeh M. , Atiqullah Muhammad , Basset Jean‐Marie 
Published: October 2014

AbstractMetathesis of cyclic alkanes catalyzed by the new surface complex [(SiO)W(Me)5] affords a wide distribution of cyclic and macrocyclic alkanes. The major products with the formula CnH2n are the result of either a ring contraction or ring expansion of cyclooctane leading to lower unsubstituted cyclic alkanes (5≤n≤7) and to an unprecedented distribution of unsubstituted macrocyclic alkanes (12≤n≤40), respectively, identified by GC/MS and by NMR spectroscopies.
Controlled Release of Fragrant Molecules with Visible Light
Authors: Wang Zhuozhi , Johns Valentine K. , Liao Yi 
Published: October 2014

AbstractControlled release of odorous molecules is the key to digital scent technology which will add another dimension to electronics. Photorelease is a cold mechanism that promises better temporal and spatial control than thermal release. Herein we report a novel material composed of an acid‐sensitive polymer carrying a fragrant aldehyde and a reversible metastable‐state photoacid. It releases the fragrant molecule under visible light, and stops releasing it after the light is turned off. A metastable‐state photoacid with a fast reverse‐reaction rate was developed to quickly stop the release after irradiation. Both the carrier polymer and the photoacid can be reused after all the fragrant molecules have been released. The material combines the advantages of visible‐light activity, fast on/off rate, easy preparation, and recyclability, and thus is promising for digital scent technology.
Supramolecular Engineering of Oligothiophene Nanorods without Insulators: Hierarchical Association of Rosettes and Photovoltaic Properties
Authors: Yagai Shiki , Suzuki Mika , Lin Xu , Gushiken Marina , Noguchi Takuya , Karatsu Takashi , Kitamura Akihide , Saeki Akinori , Seki Shu , Kikkawa Yoshihiro , Tani Yuki , Nakayama Ken‐ichi 
Published: October 2014

AbstractSupramolecular rosettes of oligothiophenes that do not bear long aliphatic tails have been designed as semiconducting nanomaterials for solution‐processable bulk heterojunction solar cells. The rosettes consist of six barbiturated thienyl[oligo(hexylthiophene)] units (Bar‐T‐hTn; n=3,4,5) aggregated by multiple hydrogen bonds, which have been directly visualized by scanning tunneling microscopy (STM) at a solid–liquid interface. 1H NMR spectroscopy in [D8]toluene showed that Bar‐T‐hTn exists as a mixture of monomers and small hydrogen‐bonded aggregates. Hierarchical organization of the hydrogen‐bonded aggregates took place through π–π stacking interactions upon casting their toluene solutions, resulting in the growth of highly ordered nanorods whose widths are consistent with the diameters of the rosettes. The nanorods could be generated in the presence of soluble fullerene derivatives via solution casting or the annealing of the resulting thin films. The solar cells fabricated based on these bulk heterojunction films showed power conversion efficiencies of 1–3 %, which are far higher than those of the non‐hydrogen‐bonded reference oligothiophene and the derivative that possesses long aliphatic tails.
Catalytic Enantioselective Quick Route to Aldol‐Tethered 1,6‐ and 1,7‐Enynes from ω‐Unsaturated Aldehydes
Authors: García Jesús M. , Odriozola José M. , Razkin Jesús , Lapuerta Irati , Odriozola Amaiur , Urruzuno Iñaki , Vera Silvia , Oiarbide Mikel , Palomo Claudio 
Published: October 2014

AbstractAn effective asymmetric route to functionalized 1,6‐ and 1,7‐enynes has been developed based on a direct cross‐aldol reaction between ω‐unsaturated aldehydes and propargylic aldehydes (α,β‐ynals) promoted by combined α,α‐dialkylprolinol ether/Brønsted acid catalysis. This synergistic activation strategy is key to accessing the corresponding aldol adducts with high stereoselectivity, both enantio‐ and diastereoselectivity. The aldol reaction also proceeds well with propargylic ketones (α,β‐ynones) thus enabling a stereocontrolled access to the corresponding tertiary alcohols. The utility of these adducts, which are difficult to prepare through standard methodology, is demonstrated by their transformation into trisubstituted bicyclic enones using standard Pauson–Khand conditions.
Smoking history predicts for increased risk of second primary lung cancer: A comprehensive analysis
Authors: Boyle John M. , Tandberg Daniel J. , Chino Junzo P. , D'Amico Thomas A. , Ready Neal E. , Kelsey Chris R. 
Published: October 2014

BACKGROUNDTobacco use is the most important risk factor for the development of lung cancer. The objective of the current study was to determine the effect of smoking on the development of second primary lung cancers (SPLCs) and other clinical outcomes after surgery for non‐small cell lung cancer (NSCLC).METHODSAll patients who underwent surgery for NSCLC at the study institution from 1995 through 2008 were identified. Rates of SPLC were analyzed based on smoking status and pack‐year exposure. Multivariate analysis was performed to determine risk factors for SPLC. Overall survival, local control, distant metastases, and postoperative mortality were also examined.RESULTSA total of 1484 patients were identified, including 98 never‐smokers. The incidence of SPLC at 3 years, 5 years, and 8 years was 5%, 8%, and 16%, respectively. Only 1 never‐smoker developed an SPLC. On multivariate analysis, which was restricted to ever‐smokers with pack‐years as a continuous variable, smoking history was found to be the only independent risk factor for SPLC (hazard ratio, 1.08; 95% confidence interval, 1.02‐1.16 [P = .031]), corresponding to an 8% increased risk per 10 pack‐year exposure. There were no differences in rates of local control or distant metastases based on smoking status. There was a trend toward lower postoperative mortality in never‐smokers compared with ever‐smokers (0% vs 3.3%; P = .069). Overall survival was found to be significantly worse for current smokers compared with former and never‐smokers.CONCLUSIONSSPLCs are rare in never‐smokers. Increasing tobacco exposure is associated with a higher risk of SPLC in patients with a history of smoking. Current smokers have an increased risk of mortality whereas former and never‐smokers have comparable survival. Cancer 2015;121:598–604. © 2014 American Cancer Society.
Statistical classification of pumpkin seed oils by direct infusion mass spectrometry: Correlation with GC‐FID profiles
Authors: Lerma‐García María Jesús , Saucedo‐Hernández Yanelis , Herrero‐Martínez José Manuel , Ramis‐Ramos Guillermo , Jorge‐Rodríguez Elisa , Simó‐Alfonso Ernesto F. 
Published: October 2014

A method to classify pumpkin seed oils according to their species (Cucurbita maxima, Cucurbita pepo, and Cucurbita moschata), and C. moschata oils according to their genetic variety (RG, Inivit C‐88 and Inivit C‐2000) using fatty acid profiles obtained by direct infusion mass spectrometry (DIMS) has been developed. For DIMS, pumpkin seed oils were 1:4 (v/v) diluted with an 85:15 propanol/methanol (v/v) mixture containing 40 mM ammonia and directly infused into the mass spectrometer using a syringe pump. The establishment of ratios of the peak abundances of the free fatty acids followed by linear discriminant analysis was employed to predict both pumpkin seed oil species and C. moschata genetic variety. Moreover, the profiles obtained with this methodology were compared with the profiles obtained by the traditional GC‐FID. Since a good correlation between both methodologies was obtained, the proposed DIMS method is a promising alternative for fatty acid fingerprinting of pumpkin oils, with the advantage that prior chromatographic separation is not required.Practical applications: Pumpkin seed oils from several species and variety, differing in their organoleptic, antioxidant, and pharmaceutical properties, are found at high prices within the organic farming and gastronomical commercial circuits. Therefore, authentication methods capable of establishing the origin and other quality parameters of pumpkin seed oils are required. In this work, a simple and quick DIMS method, capable of predicting the species and genetic variety of pumpkin seed oils has been developed. The MS intensities of the free fatty acids can be measured after a simple dilution of the oils; in this way, the conventional GC‐FID separation is avoided, being only necessary to rinse the spectrometer for 5 min between successive infusions to achieve low backgrounds and reproducible oil profiles. Thus, the proposed method is a promising alternative to the traditional GC‐FID method for fatty acid fingerprinting, with the additional advantage that previous chromatographic separation is not required.Fatty acid profiles obtained by direct infusion MS were used to predict the species and genetic variety of pumpkin seed oils.
The effect of thermal treatment on the quality changes of Antartic krill meal during the manufacturing process: High processing temperatures decrease product quality
Authors: Lu Fung Sieng Henna , Bruheim Inge , Ale Marcel Tutor , Jacobsen Charlotte 
Published: October 2014

The quality of krill products is influenced by their manufacturing process and could be evaluated by their degradation products from lipid oxidation and non‐enzymatic browning reactions. The main objectives of this study were: (i) to investigate the effect of thermal treatment on these two reactions in krill products during their manufacturing process; and (ii) to understand and postulate the possible mechanisms for non‐enzymatic browning reactions in krill products. Characterisation of krill products at different stages was obtained by determination of their lipid composition (lipid classes and phospholipids), antioxidant (α‐tocopherol and astaxanthin esters) and volatile profiles (degradation products from lipid oxidation and Strecker degradation). The use of thermal treatment resulted in lipid oxidation and subsequently led to the development of non‐enzymatic browning reactions in krill products during their manufacturing process. It is hypothesized that non‐enzymatic browning reactions in krill products might occur through Maillard reaction or lipid peroxidation pathways.Practical applications: The quality of krill products is influenced by the temperature used during their manufacturing process, and the occurrence of their degradative reactions is influenced by the chemical composition and matrix of krill products. This work provides information about the possible mechanisms of the two most commonly found reactions in the food system namely, lipid oxidation and non‐enzymatic browning reactions. This information is not only applicable to krill products but also to other food matrices containing lipid, protein, sugar, etc.The quality of krill based products is influenced by the thermal treatment used during their manufacturing process and could be evaluated by their degradation products derived from lipid oxidation and non‐enzymatic browning reactions. Therefore, the processing temperature needs to be kept as low as possible to prevent the occurrence of these reactions and subsequently preserve the quality of krill products.
Maillard reaction and lipid peroxidation contribute to non‐enzymatic browning in krill‐based products: A model study on proposed mechanisms
Authors: Lu Fung Sieng Henna , Bruheim Inge , Jacobsen Charlotte 
Published: October 2014

The main objective of this study was to further investigate whether the occurrence of Strecker degradation in krill‐based products is due to the presence of N‐Acetylglucosamine (amino sugar derived from krill exoskeleton) or lipid‐derived carbonyls. A simple model system comprising amino acids was incubated at 60°C for 0, 3, 9, and 24 h with five selected lipid‐derived carbonyls or five Strecker‐derived volatiles or an amino sugar. The presence of both amino sugar and lipid‐derived carbonyls (especially α,β‐unsaturated aldehydes) caused non‐enzymatic browning reactions: (i) pyrrole formation; (ii) browning development; and (iii) Strecker degradation of amino acids, with a faster reaction rate by amino sugar. In addition, the presence of a high level of Strecker degradation products might enhance pyrrole formation.Practical applications: This work provides information about the Strecker degradation of amino acids induced by amino sugar (N‐Acetylglucosamine) and lipid‐derived carbonyl compounds, and the increase of pyrrole formation is ascribed to the presence of a high level of Strecker degradation products. The obtained knowledge from this fundamental study explains the occurrence of Strecker degradation in krill products especially after enzymatic treatment due to the increased level of amino acids, lipid oxidation products and amino sugar derived from krill shell. This information is not only applicable to krill matrix but also to similar matrices from other food systems.Non‐enzymatic browning reactions, especially Strecker degradation of amino acids in krill‐based products during their thermal treatment, are induced either through Maillard reaction due to the presence of amino sugar derived from krill exoskeleton or through the lipid peroxidation pathway due to the presence of unsaturated aldehydes derived from lipid oxidation.
Metathesis reactions of rapeseed oil‐derived fatty acid methyl esters induced by monometallic and homobimetallic ruthenium complexes
Authors: Öztürk Bengi Özgün , Topoğlu Beyza , Karabulut Şehitoğlu Solmaz 
Published: October 2014

In this study, homobimetallic ruthenium alkylidene complexes were used for the self‐metathesis and ethenolysis reactions of methyl oleate and rapeseed oil‐derived FAME mixtures. The activity and selectivity of homobimetallic ruthenium alkylidene complexes were also compared with their monometallic analogs. It has been determined that homobimetallic complexes bearing phosphine and N‐heterocyclic carbene ligands are more active and selective catalysts than their monometallic analogs for self‐metathesis and ethenolysis reactions of rapeseed FAME mixture. Homobimetallic ruthenium complexes showed superior selectivity at 25°C toward these reactions. Conversion values of 99% with 96% selectivity toward ethenolysis products were observed by using homobimetallic ruthenium complexes. In addition to these superiorities, relatively lower amounts of double bond isomerization side‐products were obtained by using homobimetallic complexes. This catalytic approach represents a unique example for metathesis transformation of FAME mixtures at relatively low temperature (25°C) and ethylene pressure (1 atm) with high selectivity using homobimetallic ruthenium alkylidene complexes.Practical applications: This study reports the selective transformation of rapeseed oil‐derived FAME by ethenolysis reactions catalyzed by homobimetallic ruthenium alkylidene complexes. Industrially important terminal olefins as well as new polymer precursors can be synthesized in a selective manner using these catalytic systems.Ethenolysis reactions of rapeseed oil‐derived fatty acid methyl ester mixture, catalyzed by homobimetallic ruthenium alkylidene complexes exhibit high selectivity at RT.