bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparing the diurnal and seasonal variabilities of atmospheric and surface urban heat islands based on the Beijing urban meteorological network
Authors: Wang Kaicun , Jiang Shaojing , Wang Jiankai , Zhou Chunlüe , Wang Xiaoyan , Lee Xuhui 
Published: February 2017

AbstractThis study compared the diurnal and seasonal cycles of atmospheric and surface urban heat islands (UHIs) based on hourly air temperatures (Ta) collected at 65 out of 262 stations in Beijing and land surface temperature (Ts) derived from Moderate Resolution Imaging Spectroradiometer in the years 2013–2014. We found that the nighttime atmospheric and surface UHIs referenced to rural cropland stations exhibited significant seasonal cycles, with the highest in winter. However, the seasonal variations in the nighttime UHIs referenced to mountainous forest stations were negligible, because mountainous forests have a higher nighttime Ts in winter and a lower nighttime Ta in summer than rural croplands. Daytime surface UHIs showed strong seasonal cycles, with the highest in summer. The daytime atmospheric UHIs exhibited a similar but less seasonal cycle under clear‐sky conditions, which was not apparent under cloudy‐sky conditions. Atmospheric UHIs in urban parks were higher in daytime. Nighttime atmospheric UHIs are influenced by energy stored in urban materials during daytime and released during nighttime. The stronger anthropogenic heat release in winter causes atmospheric UHIs to increase with time during winter nights, but decrease with time during summer nights. The percentage of impervious surfaces is responsible for 49%–54% of the nighttime atmospheric UHI variability and 31%–38% of the daytime surface UHI variability. However, the nighttime surface UHI was nearly uncorrelated with the percentage of impervious surfaces around the urban stations.
Kinetic Resolution of Aromatic β‐Amino Acids Using a Combination of Phenylalanine Ammonia Lyase and Aminomutase Biocatalysts
Authors: Weise Nicholas J. , Ahmed Syed T. , Parmeggiani Fabio , Turner Nicholas J. 
Published: February 2017

AbstractAn enzymatic strategy for the preparation of (R)‐β‐arylalanines employing phenylalanine aminomutase and ammonia lyase (PAM and PAL) enzymes has been demonstrated. Candidate PAMs with the desired (S)‐selectivity from Streptomyces maritimus (EncP) and Bacillus sp. (PabH) were identified via sequence analysis using a well‐studied template sequence. The newly discovered PabH could be linked to the first ever proposed biosynthesis of pyloricidin‐like secondary metabolites and was shown to display better β‐lyase activity in many cases. In spite of this, a method combining the higher conversion of EncP with a strict α‐lyase from Anabaena variabilis (AvPAL) was found to be more amenable, allowing kinetic resolution of five racemic substrates and a preparative‐scale reaction with >98% (R) enantiomeric excess. This work represents an improved and enantiocomplementary method to existing biocatalytic strategies, allowing simple product separation and modular telescopic combination with a preceding chemical step using an achiral aldehyde as starting material.magnified image
Advances in Organocatalytic 1,6‐Addition Reactions: Enantioselective Construction of Remote Stereogenic Centers
Authors: Chauhan Pankaj , Kaya Uğur , Enders Dieter 
Published: February 2017

AbstractDue to the competing 1,4‐addition reactions and the distance from the chirality information, the construction of a remote stereogenic center via 1,6‐addition reactions is often regarded as a great challenge in asymmetric synthesis. Recently, the use of organocatalysts has provided new, excellent alternatives to activate the remote δ‐position and facilitate the enantioselective 1,6‐addition reactions. In this regard, different new activation modes have been devised and new types of substrates have been employed. This review describes all the recent developments in this area.magnified image
Construction of Nine‐Membered Heterocycles through Palladium‐Catalyzed Formal [5+4] Cycloaddition
Authors: Yang Li‐Cheng , Rong Zi‐Qiang , Wang Ya‐Nong , Tan Zher Yin , Wang Min , Zhao Yu 
Published: February 2017

AbstractThe first catalytic formal [5+4] cycloaddition to prepare nine‐membered heterocycles is presented. Under palladium catalysis, the reaction of N‐tosyl azadienes and substituted vinylethylene carbonates (VECs) proceeds smoothly to produce benzofuran‐fused heterocycles in uniformly high efficiency. Highly diastereoselective functionalization of the nine‐membered heterocycles through peripheral attack is also demonstrated.
Silver nanoparticle‐decorated multiwalled carbon nanotube/pramipexole nanocomposite: Synthesis, characterization and application as an antibacterial agent
Authors: Shaham Ghazaleh , Veisi Hojat , Hekmati Malak 
Published: February 2017

This work reports the preparation of multiwalled carbon nanotube/pramipexole/Ag (CNT/pra/Ag) as a novel antibacterial agent, in which pramipexole groups are utilized as linkers to secure Ag nanoparticles to carbon nanotube surfaces without agglomeration. The resulting CNT/pra/Ag sample was characterized by performing transmission and scanning electron microscopy, wavelength‐ and energy‐dispersive X‐ray, X‐ray diffraction, Fourier transform infrared, inductively coupled plasma and Raman measurements. Using this approach, monodisperse spherical Ag nanoparticles in CNT/pra/Ag have narrow size distributions with average diameters of ca 3–8 nm. The antibacterial activity of CNT/pra/Ag was investigated against bacterial species Staphylococcus aureus, methicillin‐resistant S. aureus, Pseudomonas aeruginosa and Escherichia coli using the paper‐disc diffusion method and by determining the minimal inhibitory concentration. CNT/pra/Ag showed better inhibitory activity towards Gram‐positive bacteria than Gram‐negative bacteria in this study, which indicates its potential as an antibacterial material for laboratory and medical purposes.
Adaptive Non‐Linear Control of UPFC for Stability Enhancement in a Multimachine Power System Operating with a DFIG Based Wind Farm
Authors: Routray S.K. , Patnaik R.K. , Dash P.K. 
Published: February 2017

AbstractAn instantaneous converter power based adaptive second order sliding mode control for the Unified Power Flow Controller (UPFC) in a multimachine power system penetrated with a doubly fed induction generator (DFIG) based wind farm is proposed in this paper. Instead of controlling the direct and quadrature‐axis currents of the series voltage source converter (VSC) of the UPFC, the instantaneous active and reactive power outputs are used as control variables. This mode of control dispenses the unmodelled dynamics of the VSC phase‐locked loop (PLL) system and produces a robust control for the active–reactive power, and DC voltage excursions. However, the PLL is used only to obtain the frequency component needed to generate the Pulse Width Modulation (PWM) signal. In comparison to the first order sliding surface, the second order sliding surface provides very good robustness features, finite reaching time, and chattering free sliding mode behavior. Further, the proposed controller gains of the UPFC are chosen in accordance with the various constraints imposed by the second order sliding mode approach to provide significantly superior and robust performance for a number of diverse operating conditions of the network in comparison to the conventional sliding mode controller.
A case study involving single observation experiments performed over snowy Siberia using a coupled atmosphere‐land modelling system
Authors: Suzuki Kazuyoshi , Zupanski Milija , Zupanski Dusanka 
Published: February 2017

AbstractThrough a series of single observation experiments, we investigate forecast error covariance and correlation structures by applying the Maximum Likelihood Ensemble Filter (MLEF) data assimilation method with a coupled atmosphere–land surface model. We consider a coupled approach that includes the full complexity of the cross‐component covariance and correlation structures, specifically between 2‐m air temperature and snow temperature. We show that the error covariance and correlation are complex and are strongly dependent on both weather conditions and the land surface scheme, indicating a need for further investigation of the relevance of flow‐dependent ensemble covariance in coupled systems. We also demonstrate that the use of coupled error covariance methods improves the efficiency of information transfer between the atmosphere and the land surface by allowing the well‐observed atmosphere to influence land surface variables.
Untersuchungen zum Tragverhalten von Druckgurtanschlüssen in Hohlkastenbrücken
Authors: Müller Matthias , Maurer Reinhard 
Published: February 2017

AbstractBei der Nachrechnung älterer Spannbetonbrücken mit Hohlkastenquerschnitt werden derzeit häufig große rechnerische Defizite beim Nachweis der schubfesten Verbindung zwischen gedrückter Bodenplatte und den Stegen im Bereich der Zwischenunterstützungen festgestellt. Neben erhöhten Beanspruchungen als Folge stetig steigender Verkehrslastzahlen sind diese Defizite im Wesentlichen auf die mit Einführung der DIN‐Fachberichte für den Brückenbau im Jahr 2003 geänderten Bemessungsvorschriften zurückzuführen. In Deutschland erfolgt die Ermittlung des Tragwiderstands im GZT seither auf Grundlage des Fachwerkmodells mit Rissreibung. In den hier vorgestellten Untersuchungen wird gezeigt, dass die Übertragung dieses für Stegquerschnitte entwickelten Modells auf Druckgurte mechanisch nicht begründet ist und zu sehr konservativen Ergebnissen führt. Auf Basis der Ergebnisse numerischer und analytischer Betrachtungen werden Bemessungsmodelle entwickelt, die das Tragverhalten vorwiegend gedrückter Gurtbereiche realitätsnäher erfassen. Die Kalibrierung und Verifikation der FE‐Modelle erfolgt in den durchgeführten Untersuchungen stets durch den Vergleich mit Ergebnissen gut dokumentierter Versuche aus der Literatur.
Temperaturfeldberechnung für Brücken
Authors: Sanio David , Mark Peter , Ahrens Mark Alexander 
Published: February 2017

AbstractIn statisch unbestimmten Systemen erzeugen ungleichmäßige Erwärmungen Zwangsspannungen. Für die Berechnung und Bemessung von Brücken werden diese üblicherweise durch lineare Temperaturgradienten berücksichtigt. Neben dem ver tikalen Gradienten gilt die mittlere Querschnittstemperatur als bemessungsrelevant. Gängige Regelwerke geben für beide feste Einzelwerte bzw. vereinfachte Verteilungen für die Nachrechnung vor. Diese basieren auf Untersuchungen grundlegender Bauwerkstypen, die als repräsentativ für die Gesamtheit der Brücken angesehen werden. Die daraus abgeleiteten Kennwerte erfassen daher lokale, bauwerksspezifische – und ggf. beanspruchungsmindernde – Besonderheiten, regionale klimatische Unterschiede, Beschattungssituationen sowie die Ausrichtung des Bauwerks nicht.Werden die relevanten Temperaturanteile aus einem Zeitverlauf des Temperaturfelds ermittelt, können die allgemeinen Kennwerte der Regelwerke durch bauwerksspezifische diskrete Verteilungen der Temperaturbeanspruchungen ersetzt werden. Im Beitrag wird gezeigt, wie die instationären Temperaturfelder mittels eines Tabellenkalkulationsprogramms unter Verwendung langzeitiger, lokaler Klimadaten berechnet werden können. Dazu wird die Fourier'sche Differenzialgleichung der Wärmeübertragung mit einem Finite‐Elemente‐Ansatz gelöst und um Randbedingungen der Wärmeübertragung durch äußere Einflüsse ergänzt. Besonderheiten und Eigenschaften des Verfahrens werden diskutiert und die Berechnungsergebnisse mit Messdaten eines Temperaturmonitorings an einer Spannbetonbrücke verglichen. Es zeigen sich gute Übereinstimmungen für das Temperaturfeld sowie die daraus abgeleiteten Größen wie die rechnerischen Temperaturgradienten.
Internal capsule: The homunculus distribution in the posterior limb
Authors: Qian Cheng , Tan Fei 
Published: February 2017

AbstractIntroductionIn our experience, sometimes, the symptom of patients who suffered from infarction in internal capsule (IC) do not necessarily fit the classical fiber distribution. This study aims to explain this phenomenon.Methods and MaterialsA total of 34 patients with infarction lesions in the IC were included in this study, according to the clinical symptom, divided into three groups, group A (more severe weakness of the foot than the hand), group B (more severe weakness of the hand than the foot) and group C (equal weakness of hand and foot), and group Y (with facial nerve paresis) and group N (without facial nerve paresis). Measurements included the length ratio and the angle degree of infarction lesions compared with the posterior limb of the IC (PLIC).ResultsThe length ratio of infarction lesions is significant difference between group A and group B (p = .027), the angle degree of infarction lesions is significant difference between group Y and group N (p = .038).ConclusionFrom our results, we can conclude that the hand fibers are located laterally to foot fibers in the short axis of the posterior limb of the IC, and the face fibers are located in the premedial part of the posterior limb of the internal capsule.
Influence of the Ligand of Palladium(0) Complexes on the Rate of the Oxidative Addition of Aryl and Activated Alkyl Bromides: Csp2−Br versus Csp3−Br Reactivity and Selectivity
Authors: Noverges Pedro Bárbara , Medio‐Simón Mercedes , Jutand Anny 
Published: February 2017

AbstractKinetic data obtained by means of electrochemical techniques are used to characterize the reactivity of aryl bromides and activated alkyl bromides in the oxidative addition to palladium(0) complexes generated from three precursors: Pd0(PPh3)4, {Pd0(dba)2+2 PPh3} (dba=dibenzylideneacetone) and {Pd0(dba)2+2 P(o‐Tol)3} in dimethylformamide (DMF) at 25 °C. It is established that, for the investigated substrates 1–6 and 7–11, the oxidative addition at the Csp3−Br bond is much faster than that at the Csp2−Br bond if the palladium(0) is ligated by two PPh3. This explains why the regioselectivity in Suzuki–Miyaura reactions performed from substrates bearing both Csp2−Br and Csp3−Br groups is in favor of the substitution at the Csp3−Br bond. This is in agreement with DFT calculations, which propose a SN2‐type mechanism from the bis‐ligated Pd0(PPh3)2. The oxidative addition at the Csp2−Br bond is much faster if the palladium(0) is ligated by P(o‐Tol)3 than by PPh3, in agreement with the DFT calculations, which support a concerted mechanism involving the mono‐ligated Pd0[P(o‐Tol)3] as the reactive species. This explains why the regioselectivity in Suzuki–Miyaura reactions performed from substrates bearing both Csp2−Br and Csp3−Br groups might be in favor of the substitution at the Csp2−Br bond if the ligand is P(o‐Tol)3.
The Role of Adsorption in the Electrocatalysis of Hydrazine on Platinum Electrodes
Authors: Gisbert Rubén , Boronat‐González Ana , Feliu Juan M. , Herrero Enrique 
Published: February 2017

AbstractHydrazine oxidation on platinum single‐crystal electrodes has been studied in acidic solution containing different electrolytes. It will be shown that the hydrazinium cation is adsorbed on platinum through an anodic reaction. Moreover, in the presence of chloride, this adsorption process is favored owing to the formation of an ionic pair with adsorbed chloride. In spite of the enhanced adsorption of hydrazine species in the presence of chloride, higher overpotentials are measured in these media, which reveals that the oxidation of hydrazine not only requires adsorption, but also that the adsorption mode of the species facilitates the formation of the transition state to yield the final product.
Efficient Annihilation Electrochemiluminescence of Cationic Helicene Luminophores
Authors: Li Haidong , Voci Silvia , Wallabregue Antoine , Adam Catherine , Labrador Geraldine M. , Duwald Romain , Hernández Delgado Irene , Pascal Simon , Bosson Johann , Lacour Jérôme , Bouffier Laurent , Sojic Neso 
Published: February 2017

AbstractThe electrochemistry and annihilation electrochemiluminescence (ECL) of a series of chiral cationic helicene luminophores containing various substituents were investigated in acetonitrile solvent. The electrochemical characterization evidenced a systematic reversible reduction of cationic derivatives, whereas the oxidation could be reversible or not, depending on the nature of the core heteroatoms within the structure as well as the functional‐group appendages. One of the key parameters governing the ECL intensity is, indeed, the formal redox potentials for the electrogeneration of the neutral radical and dication radical species, which will undergo the annihilation reaction. On that basis, a thermodynamic wall of efficiency was proposed in the case of ECL annihilation pathway to predict the formation efficiency of the emitting excited state and, eventually, the light emission‘s strength. This very simple wall is constructed by plotting the difference of formal potentials in function of the fluorescence wavelength, thus delimiting two domains where ECL is thermodynamically possible or unfavorable.
Design of Organic Macrocycle‐Modified Iron Oxide Nanoparticles for Drug Delivery
Authors: Skorjanc Tina , Benyettou Farah , Olsen John‐Carl , Trabolsi Ali 
Published: February 2017

AbstractPaul Ehrlich's vision of a “magic bullet” cure for disease inspires the modern design of nanocarriers whose purpose is to deliver drug cargo to specific sites in the body while circumventing endogenous immunological clearance mechanisms. Iron oxide nanoparticles (IONPs) have emerged as particularly promising nanocarriers because of their biodegradability, ability to be guided magnetically to sites of pathology, mediation of hyperthermic therapy, and imaging capabilities. In this review, we focus on the design and drug‐delivery aspects of IONPs coated with organic macrocycles (crown ethers, cyclodextrins, calix[n]arenes, cucurbit[n]urils, or pillar[n]arenes), which, by means of reversible complexation, allow for the convenient loading and release of drug molecules. Macrocycles can be attached to IONPs indirectly or directly. Indirect attachment requires the use of small organic linking molecules or conjugation to shell materials. Direct attachment requires neither. We discuss in detail drug release from the macrocycles, highlighting mechanisms that depend on external stimuli such as changes in pH, the competitive binding of ions or small molecules, or the application of ultrasound or electromagnetic radiation.
Rational Design of Advanced Photosensitizers Based on Orthogonal BODIPY Dimers to Finely Modulate Singlet Oxygen Generation
Authors: Epelde‐Elezcano Nerea , Palao Eduardo , Manzano Hegoi , Prieto‐Castañeda Alejandro , Agarrabeitia Antonia R. , Tabero Andrea , Villanueva Angeles , de la Moya Santiago , López‐Arbeloa Íñigo , Martínez‐Martínez Virginia , Ortiz María J. 
Published: February 2017

AbstractThe synthesis, photophysical characterization, and modeling of a new library of halogen‐free photosensitizers (PS) based on orthogonal boron dipyrromethene (BODIPY) dimers are reported. Herein we establish key structural factors in order to enhance singlet oxygen generation by judiciously choosing the substitution patterns according to key electronic effects and synthetic accessibility factors. The photosensitization mechanism of orthogonal BODIPY dimers is demonstrated to be strongly related to their intrinsic intramolecular charge transfer (ICT) character through the spin‐orbit charge‐transfer intersystem crossing (SOCT‐ISC) mechanism. Thus, singlet oxygen generation can be effectively modulated through the solvent polarity and the presence of electron‐donating or withdrawing groups in one of the BODIPY units. The photodynamic therapy (PDT) activity is demonstrated by in vitro experiments, showing that selected photosensitizers are efficiently internalized into HeLa cells, exhibiting low dark toxicity and high phototoxicity, even at low PS concentration (0.05–5×10−6 m).
Bifunctional Ag@SiO2/Au Nanoparticles for Probing Sequential Catalytic Reactions by Surface‐Enhanced Raman Spectroscopy
Authors: Wu Yiren , Su Dong , Qin Dong 
Published: February 2017

AbstractWe report the synthesis of bifunctional Ag@SiO2/Au nanoparticles with an “islands in the sea” configuration by titrating HAuCl4 solution into an aqueous suspension of Ag@SiO2 core–shell nanocubes in the presence of NaOH, ascorbic acid, and poly(vinyl pyrrolidone) at pH 11.9. The NaOH plays an essential role in generating small pores in the SiO2 shell in situ, followed by the epitaxial deposition of Au from the Ag surface through the pores, leading to the formation of Au islands (6–12 nm in size) immersed in a SiO2 sea. By controlling the amount of HAuCl4 titrated into the reaction system, the Au islands can be made to pass through and protrude from the SiO2 shell, embracing catalytic activity toward the reduction of 4‐nitrophenol to 4‐aminophenol by NaBH4. While the Ag in the core provides a strong surface‐enhanced Raman scattering activity, the SiO2 sea helps maintain the Au component as compact, isolated, and stabilized islands. The Ag@SiO2/Au nanoparticles can serve as a bifunctional probe to monitor the stepwise Au‐catalyzed reduction of 4‐nitrothiophenol to 4‐aminothiophenol by NaBH4 and Ag‐catalyzed oxidation of 4‐aminothiophenol to trans‐4,4′‐dimercaptoazobenzene by the O2 from air in the same reaction system.
Synthesis of Cuboctahedral CeO2 Nanoclusters and Their Assembly into Cuboid Nanoparticles by Oriented Attachment
Authors: Maya‐Johnson Santiago , Gracia Lourdes , Longo Elson , Andres Juan , Leite Edson R. 
Published: February 2017

AbstractHere, we describe a simple approach to control the oriented attachment process through selective ligand scavenging from the {100} facets of CeO2 nanoclusters. Aggregates of these nanoclusters smaller than 10 nm with controlled shapes and exposed facets were obtained. For the synthesis of the cuboctahedral CeO2 nanoclusters, we developed a solvent‐controlled synthesis approach based on a non‐hydrolytic sol–gel process and used an ester aminolysis reaction to control ligand scavenging from the {100} facets. First‐principle calculations allowed us to understand and interpret, at the atomic level, the effects of shape control on the synthesis. Fine‐tuning of the desired morphologies can be achieved by controlling the values of the surface energies, which leads to the formation of morphologies that the classic growth process does not allow.
Virus Hunting: Discovery of New Episomal Circular Viruses by Rolling Circle Techniques
Authors: Vanmechelen Bert , Rector Annabel , Maes Piet 
Published: February 2017

AbstractMany methods for the discovery of novel viruses are based on amplification of the virus using consensus or degenerate PCR primers. A downside of this approach is that it requires prior knowledge of the viral nucleotide sequence to be applicable. Presented in this unit is a method for the sequence‐independent amplification of circular viral genomes that is based on the rolling‐circle mechanism used by certain viruses in their natural replication cycle. The amplification of the virus of interest is coupled to the isolation of the viral genome by gel extraction following a restriction digestion. Once isolated, the sequence of the viral genome can be determined by nanopore sequencing, a rapid and inexpensive next‐generation sequencing technology that generates long reads in real time. The method described in this unit was originally developed for the discovery of papillomaviruses, but can be used for the identification of all types of circular DNA viruses. © 2017 by John Wiley & Sons, Inc.