bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of branch pipes on the deflagration characteristics of methane in confined space
Authors: Lv Pengfei , Zhang Jiaxu , Ju Minghua , Hu Yang , Liang Tao , Liu Kaiyuan , Pang Lei 
Published: April 2020

AbstractTo investigate the deflagration characteristics of CH4‐air mixture in confined space, fluid dynamic software Fluidyn was used to build numerical models that each consisted of a horizontal pipe and vertical branches to study the influence of different numbers of branch pipes on the deflagration propagation characteristics of CH4. Research findings suggested that the oscillation trend of the time history curve of pressure at the test point weakened and the peak initial deflagration pressure attenuated in an approximately linear manner with the increase of the propagation distance in the horizontal pipe. With the increase of the number of branches, the peak initial deflagration pressure at the same test point declined with an increasing amplitude. The vertical branch was found to have both “boosting” and “inhibiting” effects on flame propagation. And the inhibiting effect dominated as the number of vertical branches increased, which caused the flame propagation velocity within the horizontal pipe to significantly attenuate. In addition, the functions of the peak initial deflagration pressure varying with the number of branches and propagation distance in the horizontal pipe were obtained by fitting. According to the functions, the vertical branch had marked pressure venting effect on deflagration pressure in the horizontal pipe; the more the branch pipes were, the more significant the pressure venting effect was.
Low expression levels of nicotinic acetylcholine receptor subunits Boα1 and Boβ1 are associated with imidacloprid resistance in Bradysia odoriphaga
Authors: Shan Tisheng , Zhang Huihui , Chen Chengyu , Chen Anqi , Shi Xueyan , Gao Xiwu 
Published: April 2020

AbstractBACKGROUNDNeonicotinoid insecticide imidacloprid acts on insect nicotinic acetylcholine receptors (nAChRs). The mechanisms of insect resistance to imidacloprid include target‐site alteration and increased detoxification metabolism. In Bradysia odoriphaga, cytochrome P450 monooxygenase has been found involved in metabolic resistance to imidacloprid. However, the situation of target‐site related resistance to imidacloprid in B. odoriphaga is still unknown.RESULTSNine field‐collected B. odoriphaga populations showed various sensitivities to imidacloprid compared with the susceptible (SS) strain, including susceptibility, decreased susceptibility, low resistance, moderate resistance and high resistance. Seven nAChR subunit genes including α1, α2, α3, α7, α8, β1 and β3, were examined for site mutation and changes in transcription levels in field populations. No nAChR polymorphism potentially related to the resistant phenotypes was found. However, differential expression of nAChR subunit genes was found in imidacloprid resistant field population. In high imidacloprid resistant population LC‐2 (93.14‐fold resistance), the transcription levels of α1, α2 and β1 subunits were significantly down‐regulated, while the transcription levels of α3 and α8 subunits were significantly up‐regulated, compared with that in SS strain. In addition, imidacloprid acute exposure induced differential expression of nAChR subunit genes in B. odoriphaga. Furthermore, RNA interference (RNAi) suppressed the transcriptional expression of Boα1 and Boβ1, and decreased mortality of B. odoriphaga by 23.03% and 18.69%, respectively, when treated with imidacloprid.CONCLUSIONThese results indicated that, although no target‐site mutation was found in imidacloprid resistant B. odoriphaga population, the reduced expression of α1 and β1 subunits contributed to B. odoriphaga resistance to imidacloprid. © 2020 Society of Chemical Industry
Memristive Devices for Quantum Metrology
Authors: Milano Gianluca , Ferrarese Lupi Federico , Fretto Matteo , Ricciardi Carlo , De Leo Natascia , Boarino Luca 
Published: April 2020

AbstractAs a consequence of the redefinition of the International System of Units (SI), where units are defined in terms of fundamental physical constants, memristive devices represent a promising platform for quantum metrology. Coupling ionics with electronics, memristive devices can exhibit conductance levels quantized in multiples of the fundamental quantum of conductance G0 = 2e2/h. Since the fundamental quantum of conductance G0 is related only to physical constants that assume fixed value in the revised SI, memristive devices can be exploited for the practical realization of a quantum‐based resistance standard that, differently from quantum‐Hall based devices conventionally adopted as resistance standards, can operate in different ambient conditions (air, vacuum, harsh environment), in a wide range of temperatures and without the need of an applied magnetic field. In this work, the possibility of using memristive devices for quantum metrology is critically discussed, based on recent experimental and theoretical advances on quantum conductance phenomena reported in literature. Thanks to the high operational speed, high scalability down to the nanometer scale, and CMOS compatibility, memristive devices allow on‐chip implementation of a resistance standard required for the realization of self‐calibrating electrical systems and equipment with zero‐chain traceability in accordance with the revised SI.
Atmospheric pressure ionization mass spectrometry as a tool for structural characterization of lignin
Authors: Kubátová Alena , Andrianova Anastasia A. , Hatton Joshua , Kozliak Evguenii I. 
Published: April 2020

RationaleLignin occurs in a broad range of forms, e.g., native as the main support for plant walls, and processed, for which its structure depends on the nature of the industrial isolation method, such as in paper production or in biorefineries. Due to the variety of lignin sources, there is no unified agreement on the structure of lignin or even its molecular weight (MW).MethodsThe focus of this review is on the application of atmospheric pressure ionization methods to lignin analysis by mass spectrometry (MS), namely electrospray ionization (ESI) or direct analysis in real‐time (DART). Specific parameters affecting ionization including electrolytes and solvents are discussed.ResultsThe main challenge for MW determination of lignin is its heteropolymer character as well as the mass range limitations of MS instrumentation. To date, only a few studies have successfully used the mass range above m/z 1500. We present the advantage of ESI in generating multiply charged ions, allowing for a further increase in the mass range of deconvoluted mass spectra. While some methods such as DART do not address the mass range problem, they may serve as excellent imaging tools suitable for structural characterization of lignin.ConclusionsA literature review presents the recent accomplishments in lignin MS analysis by atmospheric pressure ionization techniques. Although significant breakthroughs have been made, it is essential to further improve the operating conditions and validate the methods for a broader range of feedstocks with the results being confirmed using other methods.
Novel results on nonfragile sampled‐data exponential synchronization for delayed complex dynamical networks
Authors: Zhao Can , Zhong Shouming , Zhang Xiaojun , Zhong Qishui , Shi Kaibo 
Published: April 2020

SummaryThis article investigates exponential synchronization for complex dynamical networks (CDNs) with nonfragile sampled‐data feedback control. An important yet challenging problem that contains the time delays of the controller, the uncertainties occurrence and randomness of controller gain fluctuation due to the packet loss, and time delays during data transmission is to be solved. A novel Lyapunov‐Krasovskii functional (LKF) that allows for more free matrix terms and slacks certain one of the terms to nonpositive definite is first constructed based upon special refined block matrices. By employing the novel LKF and functional analysis theory, the nonfragile sampled‐data feedback controller is developed to guarantee the exponential synchronization of CDNs and make a more optimal bound estimation of the sampled period. Finally, compared simulation examples are performed as significant to demonstrate the effective performance and the superiority of the proposed methods.
On the design of nonautonomous fixed‐time controllers with a predefined upper bound of the settling time
Authors: Gómez‐Gutiérrez David 
Published: April 2020

SummaryRecently, there has been a great deal of attention in a class of finite‐time stable dynamical systems, called fixed‐time stable, that exhibit uniform convergence with respect to its initial condition, that is, there exists an upper bound for the settling‐time (UBST) function, independent of the initial condition of the system. Of particular interest is the development of stabilizing controllers where the desired UBST can be selected a priori by the user since it allows the design of controllers to satisfy real‐time constraints. Unfortunately, existing methodologies for the design of controllers for fixed‐time stability exhibit the following drawbacks: on the one hand, in methods based on autonomous systems, either the UBST is unknown or its estimate is very conservative, leading to over‐engineered solutions; on the other hand, in methods based on time‐varying gains, the gain tends to infinity, which makes these methods unrealizable in practice. To bridge these gaps, we introduce a design methodology to stabilize a perturbed chain of integrators in a fixed‐time, with the desired UBST that can be set arbitrarily tight. Our approach consists of redesigning autonomous stabilizing controllers by adding time‐varying gains. However, unlike existing methods, we provide sufficient conditions such that the time‐varying gain remains bounded, making our approach realizable in practice.
Ultrafast Laser Manufacture of Stable, Efficient Ultrafine Noble Metal Catalysts Mediated with MOF Derived High Density Defective Metal Oxides
Authors: Guo Shuailong , Zhao Yunkun , Yuan Hao , Wang Chengxiong , Jiang Haoqing , Cheng Gary J. 
Published: April 2020

AbstractSupported metal nanoparticles (MNPs) undergo severe aggregation, especially when the interaction between MNPs and their supports are limited and weak where their performance deteriorates dramatically. This becomes more severe when catalysts are operated under high temperature. Here, it is reported that MNPs including Pt, Au, Rh, and Ru, with sub‐2 nm size can be stabilized on densely packed defective CeO2 nanoparticles with sub‐5 nm size via strong coupling by direct laser conversion of corresponding metal ions encapsulated cerous metal–organic frameworks (Ce‐MOFs). Ce‐MOF serves as an ideal dispersion precursor to uniformly encapsulate noble metal ions in their orderly arranged pores. Ultrafast laser vaporization and cooling forms uniform, ultrasmall, well‐mixed, and exceptionally dense nanoparticles of metal and metal oxide concurrently. The laser‐induced ultrafast reaction (within tens of nanoseconds) facilitates the precipitation of CeO2 nanoparticles with abundant surficial defects. Due to the well‐mixed ultrasmall Pt and CeO2 components with strong coupling, this catalyst exhibits exceptionally high stability and activity both at low and high temperatures (170–1100 °C) for CO oxidation in long‐term operation, significantly exceeding catalysts prepared by traditional methods. The scalable feature of laser and huge MOF family make it a versatile method for the production of MNP‐based nanocomposites in wide applications.
Finite‐Element‐Bemessung von Stahlverbindungen basierend auf der Komponentenmethode
Authors: Wald František , Vild Martin , Kuříková Marta , Kabeláč Jaromír , Sekal David , Maier Nadine , Da Silva Seco Laura , Couchaux Maël 
Published: April 2020

AbstractIn diesem Beitrag werden die Grundsätze der mehrstufigen Finite‐Elemente‐Modellierung für die Bemessung von Stahlverbindungen beschrieben. Der wesentliche Bestandteil der Bemessung durch finite Elemente ist die Validierung und Verifizierung des Modells und seiner Ergebnisse. Für Modelle mit Schalen‐ und Volumenkörpern handelt es sich um eine Untersuchung der Netzsensitivität. Bei der komponentenbasierten Finite‐Elemente‐Methode (CBFEM) werden die Stahlplatten mittels nichtlinearer Materialanalyse (MNA) untersucht. Ihre Tragfähigkeit im plastischen Zustand wird durch die Dehnungen begrenzt. Das Verhalten der Komponenten, z. B. von Schrauben, Ankerschrauben, Schweißnähten usw., wird durch die Einführung nichtlinearer Federn berücksichtigt, die das Verhalten der Komponenten in Bezug auf Anfangssteifigkeit, Zugtragfähigkeit und Verformungskapazität darstellen. Zur Erläuterung dieses Vorgehens wird ein Überblick über die Erfolgsgeschichte der Finite‐Elemente‐Analyse (FEA) in Stahlbauverbindungen zusammengestellt. Dieser Beitrag zeigt Unterschiede zwischen den forschungs‐ und bemessungsorientierten Modellen und den aktuellen Erkenntnissen in der Modellierung von Verbindungskomponenten. Beide haben ihre Berechtigung in weiterführenden Untersuchungen. Die Validierung und Verifizierung wird am Modell des Blockversagens aufgrund des Versagens für die Knotenblechverbindung und für die durch Biegemomente um beide Achsen belasteten Grundplatten dargestellt. Die Schlussfolgerung zeigt das Potenzial bei der Bemessung von Bauteilen, einschließlich ihrer Anschlüsse.
Effectiveness of multiscale hybrid fiber reinforced cementitious composites under single degree of freedom hydraulic shaking table
Authors: Cao Mingli , Khan Mehran 
Published: April 2020

AbstractRecently, the multiscale hybrid fiber reinforced cementitious composites (MSHyFRCC) with steel fibers, polyvinyl alcohol (PVA) fibers, and calcium carbonate whiskers had developed with improved mechanical properties under static load. Although, there is still a research gap to study its behavior and properties under the action of earthquake load. In this work, the properties of steel fibers, PVA fibers, and calcium carbonate whisker hybrid FRCC are evaluated by using single degree of freedom hydraulic shaking table. A total of 10 mixes having different mix proportions, fiber lengths, and contents of steel fibers, PVA fibers, and calcium carbonate whiskers are considered. The stress–strain curves, failure mode of cubes, compressive strength, peak micro‐strain, strain energy density, failure mode of column specimen, displacement‐time curves, strain‐time curves, and top acceleration‐time curves are studied. The multiscale hybrid fibers offer resistances against crack growth under dynamic load which results in longer time period with improved displacement, strain, and acceleration. The 1.5% steel fibers of 13 mm, 0.75% PVA fibers of 6 mm with 1% calcium carbonate whiskers and 1.25% steel fibers of 35 mm, 0.55% PVA fibers of 12 mm with 2% calcium carbonate whiskers are proposed to be the optimized mixes for short‐ and long‐length hybrid fibers, respectively.
Herz und Herz-Kreislauf-System in der (kultur-)historischen Betrachtung
Authors: Koehler Ulrich , Hildebrandt Olaf , Hildebrandt Wulf , Aumüller Gerhard 
Published: April 2020

ZusammenfassungWer waren die Entdecker des Herz-Kreislauf- und des Kapillarsystems? Fragt man die Studenten eines höheren Semesters nach historischen Bewandtnissen, die den Weg der Medizin in die Gegenwart entscheidend beeinflusst haben, so gibt es in der Regel keine oder eine falsche Antwort. Wer wissenschaftliches Denken und Handeln erfahren will, kommt nicht umhin, sich auch mit der historischen und kulturellen Entwicklung der Medizin auseinanderzusetzen. Die Naturwissenschaften und die Medizin liefern jedoch wie kaum eine andere Wissenschaft den Beweis, dass im Sinne der Patienten beständig nach neuen Wegen und Erkenntnissen gesucht werden muss. Dieser Artikel soll einen Beitrag dazu leisten, daran zu erinnern, wie es zur Entdeckung des Herz-Kreislauf-Systems und der kulturhistorischen Bedeutung des Herzens gekommen ist. Nicht zuletzt soll er jedoch auch einen Eindruck vermitteln, unter welch großem Einsatz – mitunter des eigenen Lebens – und auf welch steinigem Wege der Erkenntnisgewinn zustande gekommen ist.
Knowledge recombination along the technology life cycle
Authors: Kalthaus Martin 
Published: April 2020

AbstractThis study sheds light on how recombination of different kinds of knowledge changes along the technology life cycle. From a theoretical point of view, the cyclical technology life cycle model is extended to account for the influence of recombination of different kinds of knowledge in the different life cycle phases. This model is empirically tested for the technological life cycle of wind power and photovoltaics in Germany for the period from 1970 until 2006. Patent forward citations are considered as recombinatorial success and inventors’ patenting experience proxy different kinds of knowledge. Negative binomial regressions as well as rolling-window regressions are used to estimate the relevance of different kinds of knowledge along the technology life cycle. Results reveal that different kinds of knowledge matter along the technology life cycle. In the era of ferment, knowledge from domains external to the technology is relevant, but for the dominant design and the era of incremental change, new and specialized knowledge is most important. However, there are technological differences and deviations from the model. Rolling-window regressions reveal nuanced changes in the life cycle phases. The results have several policy and management implications, especially for the timing of whom to fund or hire for inventive activity.
Direct infrared spectroscopy for the size-independent identification and quantification of respirable particles relative mass in mine dusts
Authors: Stach Robert , Barone Teresa , Cauda Emanuele , Krebs Patrick , Pejcic Bobby , Daboss Sven , Mizaikoff Boris 
Published: April 2020

AbstractDue to the global need for energy and resources, many workers are involved in underground and surface mining operations where they can be exposed to potentially hazardous crystalline dust particles. Besides commonly known alpha quartz, a variety of other materials may be inhaled when a worker is exposed to airborne dust. To date, the challenge of rapid in-field monitoring, identification, differentiation, and quantification of those particles has not been solved satisfactorily, in part because conventional analytical techniques require laboratory environments, complex method handling, and tedious sample preparation procedures and are in part limited by the effects of particle size. Using a set of the three most abundant minerals in limestone mine dust (i.e., calcite, dolomite, and quartz) and real-world dust samples, we demonstrate that Fourier transform infrared (FTIR) spectroscopy in combination with appropriate multivariate data analysis strategies provides a versatile tool for the identification and quantification of the mineral composition in relative complex matrices. An innovative analytical method with the potential of in-field application for quantifying the relative mass of crystalline particles in mine dust has been developed using transmission and diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) within a unified multivariate model. This proof-of-principle study shows how direct on-site quantification of crystalline particles in ambient air may be accomplished based on a direct-on-filter measurement, after mine dust particles are collected directly onto PVC filters by the worker using body-mounted devices. Without any further sample preparation, these loaded filters may be analyzed via transmission infrared (IR) spectroscopy and/or DRIFTS, and the mineral content is immediately quantified via a partial least squares regression (PLSR) algorithm that enables the combining of the spectral data of both methods into a single robust model. Furthermore, it was also demonstrated that the size regime of dust particles may be classified into groups of hazardous and less hazardous size regimes. Thus, this technique may provide additional essential information for controlling air quality in surface and underground mining operations.
Investigation of an Elevational Gradient Reveals Strong Differences Between Bacterial and Eukaryotic Communities Coinhabiting Nepenthes Phytotelmata
Authors: Gilbert Kadeem J. , Bittleston Leonora S. , Naive Mark Arcebal K. , Kiszewski Anthony E. , Buenavente Perry Archival C. , Lohman David J. , Pierce Naomi E. 
Published: April 2020

AbstractElevation is an important determinant of ecological community composition. It integrates several abiotic features and leads to strong, repeatable patterns of community structure, including changes in the abundance and richness of numerous taxa. However, the influence of elevational gradients on microbes is understudied relative to plants and animals. To compare the influence of elevation on multiple taxa simultaneously, we sampled phytotelm communities within a tropical pitcher plant (Nepenthes mindanaoensis) along a gradient from 400 to 1200 m a.s.l. We use a combination of metabarcoding and physical counts to assess diversity and richness of bacteria, micro-eukaryotes, and arthropods, and compare the effect of elevation on community structure to that of regulation by a number of plant factors. Patterns of community structure differed between bacteria and eukaryotes, despite their living together in the same aquatic microhabitats. Elevation influences community composition of eukaryotes to a significantly greater degree than it does bacteria. When examining pitcher characteristics, pitcher dimorphism has an effect on eukaryotes but not bacteria, while variation in pH levels strongly influences both taxa. Consistent with previous ecological studies, arthropod abundance in phytotelmata decreases with elevation, but some patterns of abundance differ between living inquilines and prey.