bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two classes of heterocycles—6,8‐dioxabicyclo[3.2.1]octanes and cyclopentenols from the same reagents: A quantum‐chemical comparison of mechanism
Authors: Vitkovskaya Nadezhda M. , Orel Vladimir B. , Kobychev Vladimir B. , Schmidt Elena Yu. , Trofimov Boris A. 
Published: August 2018

AbstractMost of the strategies for the synthesis of 6,8‐dioxabicyclo[3.2.1]octanes (BCO) and cyclopentenols (CP), which show high biological and pharmaceutical activity, are multistage and/or require hardly accessible starting materials and catalysts. The general method for BCO and CP preparation in a single preparative stage from two simple reagents, ketones and acetylene, under the action of an available super‐basic catalytic system KOH/DMSO becomes promising for the development of general approaches to the design of these classes of biologically active compounds. The mechanism of competing reactions yielding both 7‐methylene‐6.8‐dioxabicyclo[3.2.1]‐octanes and functionalized cyclopentenoles from their common intermediate 1,5‐diketones and acetylene in the KOH/DMSO superbasic media is investigated using the B2PLYP/6‐311++G**//B3LYP/6‐31+G* calculations with particular attention to the diastereoselectivity aspects of individual stages.
Modified composite nonlinear feedback control for output tracking of nonstep signals in singular systems with actuator saturation
Authors: Jafari E. , Binazadeh T. 
Published: August 2018

SummaryThis paper considers output tracking of nonstep reference signals for multi‐input multi‐output singular systems subject to actuator saturation and external disturbances. Singularity of the system alongside the actuator saturation constraint and external disturbances adds more complexity to stability analysis and controller design than normal systems. Moreover, the problem of output tracking of nonstep reference signals in singular systems via the composite nonlinear feedback (CNF) control law is not studied so far in the literature, and this article will investigate this problem for the first time by proposing the modified CNF control law. For this purpose, first, a singular reference generator system is constructed to produce the desired nonstep reference signal. Then, the dynamical error system is obtained by defining a new state vector as the tracking error and augmenting it to the main system. Different parts of the modified CNF control law are designed afterwards. Due to complexities caused by the singularity of the system and the saturation constraint, detailed mathematical calculations are done. In this regard, a theorem is given that guarantees the tracking problem for three different cases of the saturation function. Moreover, the given theorem will investigate the uniform ultimate boundedness analysis of the tracking error in the face of external disturbances. Finally, the theoretical results are affirmed by computer simulations through three examples to verify the performance and applicability of the proposed control law.
On finite‐time robust stabilization via nonlinear state feedback
Authors: Zimenko K. , Polyakov A. , Efimov D. 
Published: August 2018

SummaryA nonlinear control law is designed for finite‐time stabilization of a chain of integrators. The method is based on the implicit Lyapunov function technique and homogeneity properties. The scheme of control parameter selection is presented by a linear matrix inequality. The method is simple in implementation and does not assume an online procedure for the computation of the implicit Lyapunov function value at the current state that is an improvement with respect to the works of Polyakov et al. The control law is presented in an explicit form and allows finding the values of all control parameters that make the solution one of the most constructive. The theoretical results are supported by numerical examples.
Three‐year fade and inter‐fade duration statistics from the Q‐band Alphasat propagation experiment in Madrid
Authors: Pimienta‐del‐Valle Domingo , Riera José Manuel , Garcia‐del‐Pino Pedro , Siles Gustavo A. 
Published: August 2018

SummaryPropagation campaigns are carried out at different frequencies and geographical areas to characterize the slant‐path propagation channel. One of the objectives of the Alphasat Propagation Experiment is to evaluate the performance of satellite links that operate in the Q/V band. Since March 2014, the copolar level of the Alphasat Q‐band beacon signal has been measured at Universidad Politécnica de Madrid, Spain.The fade dynamics—fade and inter‐fade durations—results for three complete years (March 2014 to February 2017) of measurements are presented in this paper. Moreover, the experimental setup and receiver characteristics are described in detail. The collected data (with a mean availability of 97%) can be used to evaluate the atmospheric propagation impairments with a very good degree of accuracy. The probability of occurrence and the fraction of time of fade duration for an average‐year have been compared with the ITU‐R and CRC models with moderate agreement. For this reason, a modeling effort has been made leading to the conclusion that there is room for improvement in the models.
Borax Catalysed Domino Synthesis of Highly Functionalised Spirooxindole and Chromenopyridine Derivatives: X‐Ray Structure, Hirshfeld Surface Analysis and Molecular Docking Studies
Authors: Molla Aniruddha , Ranjan Subham , Rao Mugada Sugunakara , Dar Arif Hassan , Shyam Mousumi , Jayaprakash Venkatesan , Hussain Sahid 
Published: August 2018

AbstractBorax efficiently catalysed the synthesis of a series of spirooxindole and chromeno[2, 3‐b]pyridine‐3‐carbonitrile derivatives in domino fashion via Knoevenagel condensation followed by Michael addition. This synthetic scheme is operationally simple, affording excellent yield and can be considered as an approach towards ‘green chemistry’. In‐silico docking studies of the synthesized molecules were carried to investigate the anti‐tumor activity and to predict its binding affinity and orientation at the active site of human anaplastic lymphoma protein (Protein Data Bank (PDB): 2xp2). Molecular docking studies indicated that 2‐amino‐5′‐chloro‐7,7‐dimethyl‐2′,5‐dioxo‐5,6,7,8‐tetrahydrospiro[chromene‐4, 3′‐indoline]‐3‐carbonitrile (1 e) and 2′‐amino‐5‐chloro‐2,5′‐dioxo‐5′H‐spiro[indoline‐3, 4′‐pyrano[3, 2‐c]chromene]‐3′‐carbonitrile (2 b) appeared to show strong interactions at the receptor active site with predicted binding energy of −8.47 kcal/mol and −9.19 kcal/mol respectively. A detailed analysis of topology of the compounds 1 e and 2 b were also determined by X‐ray crystallography and Hirshfeld surface analysis to get an insight of the packing and intermolecular interactions in their molecular structure.
Nitrogen Codoped Unique Carbon with 0.4 nm Ultra‐Micropores for Ultrahigh Areal Capacitance Supercapacitors
Authors: Zhou Junshuang , Hou Li , Luan Sunrui , Zhu Jinlong , Gou Huiyang , Wang Dong , Gao Faming 
Published: August 2018

AbstractA full understanding of ion transport in porous carbon electrodes is essential for achieving effective energy storage in their applications as electrochemical supercapacitors. It is generally accepted that pores in the size range below 0.5 nm are inaccessible to electrolyte ions and lower the capacitance of carbon materials. Here, nitrogen‐doped carbon with ultra‐micropores smaller than 0.4 nm with a narrow size distribution, which represents the first example of electrode materials made entirely from ultra‐microporous carbon, is prepared. An in situ electrochemical quartz crystal microbalance technique to study the effects of the ultra‐micropores on charge storage in supercapacitors is used. It is found that ultra‐micropores smaller than 0.4 nm are accessible to small electrolyte ions, and the area capacitance of obtained sample reaches the ultrahigh value of 330 µF cm−2, significantly higher than that of previously reported carbon‐based materials. The findings provide a better understanding of the correlation between ultra‐micropore structure and capacitance and open new avenues for design and development of carbon materials for the next generation of high energy density supercapacitors.
Time‐aware service recommendation: Taxonomy, review, and challenges
Authors: Mezni Haithem , Fayala Mayssa 
Published: August 2018

SummaryNowadays, a huge number of available Web services offer the same functionalities and a high quality of service, which makes the selection of suitable services a difficult task. In such situation, the services must be differentiated by additional criteria such as users' ratings. To meet this goal, recommendation techniques become a natural choice to cope with the challenging task of optimal service selection and to help consumers satisfy their needs and preferences. However, most existing models on service recommendation are static, whereas in the real world, the perception and popularity of Web services may continually change, and users' preferences and habits also shift frequently. Time is becoming an increasingly important factor in recommender systems, since time effects influence users' preferences to a large extent. In addition, quality‐of‐service performance of Web services is strongly linked to the service status and network environments, which are variable against time. Recently, a wide range of service recommendation approaches, dealing with the time dimension in user modeling and recommendation strategies, have been proposed. Thus, the purpose of this survey is to present a comprehensive study and analysis of the state‐of‐the‐art on time‐aware service recommendation. We identify the techniques used in recommender systems to provide the best services. Moreover, we present a classification of time‐aware recommender systems based on the target recommendation time, the type of relationship between users, and the type of feedback. Besides, we present a comparison between time‐aware recommendation approaches, and we discuss their advantages and disadvantages. Finally, challenges and requirements of time‐aware service recommendation as well as the future directions are identified according to the studied approaches.
TosKer: A synergy between TOSCA and Docker for orchestrating multicomponent applications
Authors: Brogi Antonio , Rinaldi Luca , Soldani Jacopo 
Published: August 2018

SummaryHow to flexibly manage complex applications across heterogeneous cloud platforms is one of the main concerns in today's IT enterprise. The OASIS standard TOSCA (Topology and Orchestration Specification for Cloud Applications) and the Docker ecosystem are two emerging solutions trying to address this problem from different perspectives. In this paper, we propose a solution that tries to synergically combine the pros of both TOSCA and of Docker. More precisely, we propose a TOSCA‐based representation for specifying the software components and the Docker containers forming an application. We also present TosKer, an engine for orchestrating the management of multicomponent applications based on the proposed TOSCA representation and on Docker. Finally, we illustrate how TosKer was fruitfully exploited in a concrete case study based on a third‐party application.
Optimized extraction of secoiridoid glycosides from Gentianae radix by pressurized liquid extraction using a Box–Behnken Design
Authors: Chen Bao , Liu Zhengbo , Qu Di , Wang Yufang , Huo Xiaohui , Li Zhiman , Sun Yinshi 
Published: August 2018

AbstractIn this study, a Box–Behnken design was used to optimize experimental conditions for the pressurized liquid extraction of three secoiridoid glycosides (swertiamarin, gentiopicroside, and trifloroside) from Gentianae radix. Optimal conditions for the pressurized liquid extraction were determined through a carefully designed optimization process comprising two distinct stages: a single‐factor experiment followed by a Box–Behnken design. The optimized conditions involve a single 18‐min extraction cycle using 61% aqueous ethanol and a 3/5 (g/g) ratio of Gentianae radix to diatomite. High‐performance liquid chromatography was used to determine experimental yields, which were consistent with the predicted values under optimized conditions. Consistently high yields over short extraction times were achieved with the optimized pressurized liquid extraction conditions, as compared to the results of comparative ultrasound‐assisted and Soxhlet extractions. The results demonstrate the multiple advantages of pressurized liquid extraction for the extraction of secoiridoid glycosides from Gentianae radix: reduced extraction times, convenient setup, and high extraction efficiency.
Neue Bahnbrücke Kattwyk
Authors: Stockmann Rico , Baur Tillmann 
Published: August 2018

AbstractHerrn Dipl.‐Ing., Dr.‐Ing. E. h. Reiner Saul zur Vollendung des 80. Lebensjahres gewidmetIm Hamburger Hafen entsteht derzeit mit 130,85 m Hauptspannweite die größte Hubbrücke Deutschlands. Dieser Beitrag berichtet von Planung und Bau dieser zweigleisigen Eisenbahnbrücke.
Erweiterung der Zentralmensa der Universität Kassel
Authors: Maier Markus , Fischer Michael , Pietro Martin 
Published: August 2018

AbstractHerrn Dipl.‐Ing., Dr.‐Ing. E. h. Reiner Saul zur Vollendung des 80. Lebensjahres gewidmetDie Erweiterung der Zentralmensa an der Universität in Kassel wurde als freischwebende Stahl‐Glas‐Konstruktion über dem Wirtschaftshof entworfen. Die komplexe Maßnahme umfasst dabei besondere Detailplanungen an der Bestandskonstruktion, Tiefbauarbeiten, Stahlbetonkonstruktionen und Stahlbaumaßnahmen, so dass alle wesentlichen Fachdisziplinen in einer Baumaßnahme vereint wurden. Bereits zu Beginn der Vorplanung wurde dabei auf die Vorteile der BIM‐Modellierung zurückgegriffen, um die Verbindungen zwischen Bestandskonstruktion und Neubau sinnvoll zu erfassen.
Neue Wege im Verbundbrückenbau
Authors: Mansperger Tobias , Jung Rolf 
Published: August 2018

AbstractHerrn Dipl.‐Ing., Dr.‐Ing. E. h. Reiner Saul zur Vollendung des 80. Lebensjahres gewidmetDie vergleichsweise junge Bauweise des Verbundbrückenbaus gewinnt zunehmend an Bedeutung und birgt gleichzeitig großes Innovationspotenzial.Einige innovative Konstruktionsweisen für die Querschnittgestaltung von Brücken in allen Spannweitenbereichen beruhen auf dem Prinzip, den Stahlbauteil als Hohlkastenkonstruktionen auszuführen und diese mit Betonhalbfertigteilen zu ergänzen. Dadurch entstehen bereits im Bauzustand robuste Konstruktionen mit hohem Vorfertigungsgrad, die es erlauben, auf Schalkonstruktionen zu verzichten. Sonderkonstruktionen mit Mittelträgern, deren Obergurte über der Fahrbahnebene verlaufen, eignen sich für einteilige Überbauten für beide Richtungsfahrbahnen und überqueren kreuzende Verkehrswege mit minimalem Gradientenabstand. Sie stellen gestalterisch ansprechende Alternativen zu klassischen oben liegenden Tragwerken, wie Stabbogenbrücken oder seilverspannten Tragwerken, dar.Sogenannte Orthoverbundplatten, bestehend aus einer leichten orthotropen Platte und einer im Verbund wirkenden, dünnen Aufbetonschicht, bilden eine leichte Fahrbahnplatte für den Großbrückenbau, deren Robustheit allen zeitgemäßen Anforderungen an Ermüdungssicherheit genügt.
WILLINGNESS TO RENT PUBLIC LAND FOR ROTATIONAL GRAZING: THE IMPORTANCE OF RESPONSE BEHAVIOR
Authors: MOONEY DANIEL F. , BOLINSON COURTNEY , BARHAM BRADFORD L. 
Published: August 2018

AbstractEx ante analyses of agricultural practices often examine stated preference data, yet response behavior as a potential source of bias is often disregarded. We use survey data to estimate producers’ willingness to rent public land for rotational grazing in Wisconsin and combine it with information on nonrespondents to control for nonresponse and avidity effects. Previous experience with managed grazing and rental decisions influenced who responded as well as their rental intentions. These effects do not produce discernable bias but still encourage attention to this possibility in other ex ante contexts. Land rental determinants and willingness-to-pay estimates are also related to grazing initiatives.
Determinants of treatment of mental disorders in Lebanon: barriers to treatment and changing patterns of service use
Authors: Karam E. G. , Karam G. E. , Farhat C. , Itani L. , Fayyad J. , Karam A. N. , Mneimneh Z. , Kessler R. , Thornicroft G. 
Published: August 2018

AbstractAimsTo investigate for the first time the determinants and barriers of seeking help for mental disorders in the Arab world based on a national study: Lebanese Evaluation of the Burden of Ailments and Needs Of the Nation (L.E.B.A.N.O.N).MethodsA nationally representative (n = 2857) and multistage clustered area probability household sample of adults ≥18 years and older was assessed for lifetime and 12 months mental disorders using the Composite International Diagnostic Interview. In addition, detailed information was obtained on help- seeking behaviour and barriers to treatment.ResultsIn total, 19.7% of the Lebanese with mental disorders sought any type of treatment: 91% of those who sought treatment did so within the health sector. Severity and perceived severity of disorders predicted seeking help, the highest being for panic disorder. The greatest barrier to seek help was low perceived need for treatment (73.9%). Stigma was reported to be a factor only in 5.9% of those who thought about seeking treatment. Eighty per cent of the Lebanese reported they would not be embarrassed if friends knew they were seeking help from a professional.ConclusionsA small fraction of Lebanese seek help for their mental health problems: female gender, higher education and income are predictors of positive attitudes to help seeking. Severity and recognition of disorders, more than stigma, to get treatment seem to be the most important factors in determining help seeking. The findings underscore the importance of helping the public recognise mental health disorders.
Modulation of Low‐Altitude Ionospheric Upflow by Linear and Nonlinear Atmospheric Gravity Waves
Authors: Burleigh M. R. , Heale C. J. , Zettergren M. D. , Snively J. B. 
Published: August 2018

AbstractThis study examines how thermospheric motions due to gravity waves (GWs) drive ion upflow in the F region, modulating the topside ionosphere in a way that can contribute to ion outflow. We present incoherent scatter radar data from Sondrestrom, from 31 May 2003 which showed upflow/downflow motions, having a downward phase progression, in the field‐aligned velocity, indicating forcing by a thermospheric GW. The GW‐upflow coupling dynamics are investigated through the use of a coupled atmosphere‐ionosphere model to examine potential impacts on topside ionospheric upflow. Specifically, a sequence of simulations with varying wave amplitude is conducted to determine responses to a range of transient forcing reminiscent of the incoherent scatter radar data. Nonlinear wave effects, resulting from increases in amplitude of the modeled GW, are shown to critically impact the ionospheric response. GW breaking deposits energy into smaller scale wave modes, drives periods of large field‐aligned ion velocities, while also modulating ion densities. Complementary momentum transfer increases the mean flow and, through ion‐neutral drag, can increase ion densities above 300 km. Ionospheric collision frequency (cooling) and photoionization effects (heating), both dependent on ionospheric density, modify the electron temperature; these changes conduct quickly up geomagnetic field lines driving ion upflow at altitudes well above initial disturbances. This flow alters ion populations available for high‐altitude acceleration processes that may lead to outflow into the magnetosphere. We have included a representative source of transverse wave heating which, when supplemented by our GWs, illustrates strengthened upward fluxes in the topside ionosphere.
The Radiative Feedback During the ENSO Cycle: Observations Versus Models
Authors: Kolly A. , Huang Y. 
Published: August 2018

AbstractObservational and model data are used to study the radiative feedbacks during the El Niño–Southern Oscillation (ENSO) cycle. We extend the previous works by analyzing the feedbacks with respect to not only top‐of‐atmosphere (TOA) but also the surface and atmospheric radiation budgets, using a newly developed set of radiation kernels. We find that the tropical radiative budgets undergo distinctive variations during ENSO. The radiative perturbation is especially significant for the atmospheric energy budget. We find that the cloud feedback during the developing phase of ENSO heats the atmosphere over the west and central Pacific differentially, which acts to strengthen the development. We also find that a prominent cloud feedback bias persists in the newer version global climate models. This bias results from wrong extent of compensation between longwave and shortwave effects, which points to the importance of validating the radiative sensitivity of clouds in the general circulation models.
Increased glutamine anabolism sensitizes non-small cell lung cancer to gefitinib treatment
Authors: Wang Liang , Peng Wen , Wu Tianming , Deng Pengchi , Zhao Ying-Lan 
Published: August 2018

AbstractTo better understand the resistance mechanism of non-small cell lung cancers (NSCLCs) to gefitinib, the metabolic profiles of gefitinib-resistant A549 cells and gefitinib-sensitive PC-9 cells were analyzed with a metabolomics analytical platform. A549 and PC-9 cells exhibited significant differences in the levels of glutamine-related metabolites. After gefitinib treatment, the glutamine level decreased in A549 cells but showed no change in PC-9 cells. The glutamine consumed by A549 cells was used to generate ATP and glutathione (GSH). As glutamine utilization was suppressed in gefitinib-treated PC-9 cells, the resulting ATP shortage and ROS accumulation led to cell death. The difference in glutamine metabolism was caused by differential changes in the levels of glutamine synthetase (GS, encoded by glutamate-ammonia ligase (GLUL)). GLUL expression was upregulated in gefitinib-sensitive cells, but it was either absent from gefitinib-resistant cells or no significant change was observed in the gefitinib-treated cells. GLUL overexpression in A549 cells significant sensitized them to gefitinib and decreased their invasive capacity. Conversely, knockout GS in PC-9 cells reduced gefitinib sensitivity and enhanced metastasis. Furthermore, the continuous exposure of gefitinib-sensitive HCC827 cells to gefitinib created gefitinib-resistant (GR) HCC827 cells, which exhibited a GLUL deletion and resistance to gefitinib. Thus, GLUL plays a vital role in determining the sensitivity of NSCLCs to gefitinib. Elevated GS levels mediate increased glutamine anabolism, and this novel mechanism sensitizes NSCLCs to gefitinib. The inhibition of glutamine utilization may serve as a potential therapeutic strategy to overcome gefitinib resistance in the clinic.
Ohmic transition at contacts key to maximizing fill factor and performance of organic solar cells
Authors: Tan Jun-Kai , Png Rui-Qi , Zhao Chao , Ho Peter K. H. 
Published: August 2018

AbstractWhile thermodynamic detailed balance limits the maximum power conversion efficiency of a solar cell, the quality of its contacts can further limit the actual efficiency. The criteria for good contacts to organic semiconductors, however, are not well understood. Here, by tuning the work function of poly(3,4-ethylenedioxythiophene) hole collection layers in fine steps across the Fermi-level pinning threshold of the model photoactive layer, poly(3-hexylthiophene):phenyl-C61-butyrate methyl ester, in organic solar cells, we obtain direct evidence for a non-ohmic to ohmic transition at the hole contact that lies 0.3 eV beyond its Fermi-level pinning transition. This second transition corresponds to reduction of the photocurrent extraction resistance below the bulk resistance of the cell. Current detailed balance analysis reveals that this extraction resistance is the counterpart of injection resistance, and the measured characteristics are manifestations of charge carrier hopping across the interface. Achieving ohmic transition at both contacts is key to maximizing fill factor without compromising open-circuit voltage nor short-circuit current of the solar cell.