bluuebunny/crossref_metadata_2025 huggingface dataset:
Real‐Time and Broadband Terahertz Wave Scattering Manipulation via Polarization‐Insensitive Conformal Graphene‐Based Coding Metasurfaces
Authors: Rouhi Kasra , Rajabalipanah Hamid , Abdolali Ali
Published: December 2017

Here, for the first time, the real‐time and broadband manipulation of terahertz (THz) waves are acquired by introducing a multifunctional graphene‐based coding metasurface (GBCM). The designed structure consists of subwavelength patterned graphene units whose operational statuses can be dynamically switched between two digital states of “0” and “1”. By engineering the spatial distribution of chemical potentials across the GBCM, various scattering patterns having single, two, four, and numerous reflection beams are elaborately achieved just within one planar structure. To compute the far‐field pattern of GBCM, an inverse discrete Fourier transform (IDFT) is established, providing a fast and efficient design method. The proposed GBCM provides a low reflection bellow −10 dB over a broad frequency band ranging from 1 THz to 1.9 THz. In addition, the metasurface retains its low reflection behavior in a wide range of incident wave angles for both TE and TM polarizations. According to conformal invariance of graphene sheets, the stealth property of GBCM is well preserved while wrapping around a curved object. The proposed technique of real‐time scattering manipulation leads to multifunctional THz devices, opening new routes contributing to numerous applications such as imaging and stealth technology.
A Photoinduced Reversible Phase Transition in a Dipeptide Supramolecular Assembly
Authors: Li Xianbao , Fei Jinbo , Xu Youqian , Li Dongxiang , Yuan Tingting , Li Guangle , Wang Chenlei , Li Junbai
Published: December 2017

Tunable supramolecular assembly has found various applications in biomedicine, molecular catalysis, optoelectronics, and nanofabrication. Unlike traditional covalent conjugation, non‐covalent introduction of a photoswitchable moiety enables reversible photomodulation of non‐photosensitive dipeptide supramolecular assembly. Under light illumination, a long‐lived photoacid generator releases a proton and mediates the dissociation of dipeptide‐based organogel, thereby resulting in sol formation. Under darkness, the photoswitchable moiety entraps a proton, resulting in gel regeneration. Furthermore, accompanying the isothermal recycled gel–sol transition in a spatially controlled manner, renewable patterns are spontaneously fabricated. This new concept of light‐controlled phase transition of amino acid‐based supramolecular assemblies will open up the possibility of wide applications.
Rumex abyssinicus (mekmeko) extract as cleaner approach for dyeing in product manufacture: Optimization and modeling studies
Authors: Mohammed Shegaw Ahmed , Panda Rames C. , Madhan Balaraman , Demessie Berhanu Assefa
Published: December 2017

Some of the synthetica dyes, used in leather dyeing, are carcinogenic. Hence an eco‐benign dyeing is made for leather based on mekmeko (Rumex abyssinicus) extract that contains the anthraquinones, a natural dyeing constituent containing bioactive compounds. It is the first time where this material is tried for dyeing application in leather manufacture. The Langmuir adsorption isotherm is supported by a thermodynamic model and is augmented using intra‐particle diffusion model. The optimum concentration of the extract for dyeing was 20% based on the weight of the undyed crust leather (dry). For the modeling and optimization studies of mekmeko‐based dyeing process, response surface methodologies and artificial neural network were used. The pH, temperature, and time effects on exhaustion of the dye were studied. The optimized conditions were found to be pH 4.5, temperature 60 °C, and duration 5.5 hr. The exhaustion level of mekmeko extract in dyeing process under optimized conditions was found to be 72%. Kinetic models explain adsorption using different adsorption isotherms. The leathers were treated with different pre‐ or post‐mordants dyeing with mekmeko, and multiple colors were obtained depending on the types of mordants used. The overall results in this study indicated that the mekmeko‐dyed leathers exhibit good fastness and organoleptic characteristics.
Poly(vinylidene fluoride)–polyacrylonitrile blend flat‐sheet membranes reinforced with carbon nanotubes for wastewater treatment
Authors: Wu Yanyan , Gao Ruichang , Gao Shenghan , Li Mingxue
Published: December 2017

In this reported study, poly(vinylidene fluoride) (PVDF) and polyacrylonitrile (PAN) blend flat‐sheet membranes were prepared via a phase‐inversion method with various loadings of multiwalled carbon nanotubes. The effects of the carbon nanotubes (CNTs) on the performance and morphology of the PVDF–PAN composites were investigated via tests of the pure water flux and rejection of bovine serum albumin, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and contact angle (CA) analysis. The experimental results demonstrate that the CNTs contributed to the improvement of the flux and hydrophilicity of the membranes. The maximum value of the flux was 398.1 L m−2 h−1, and the value of CA for the composite membranes was found to be 48°. In addition, the results of the mechanical properties tests illustrate that the brittleness and plasticity of the hybrid membranes were greatly improved by the presence of the CNTs. The flux recovery ratio was maintained at 75%; this demonstrated that the PVDF–PAN membranes enhanced with the CNTs possessed good antifouling performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46155.
Thermal, mechanical, and surface properties of poly(vinyl alcohol) (PVA) polymer modified cementitious composites for sustainable development
Authors: Lu Zeyu , Hanif Asad , Lu Cong , Sun Guoxing , Cheng Yu , Li Zongjin
Published: December 2017

This study aimed to investigate the effect of poly(vinyl alcohol) (PVA) polymer on the thermal, mechanical, and surface properties on cementitious composites for sustainable development. Thermal properties of the PVA‐modified cement paste, including thermal insulation and energy absorption ability, were first studied and correlated with the porosity and microstructures. The experimental results indicated that the thermal conductivity of cement paste can be greatly reduced by 42.9% with 2.0 wt % addition of PVA due to the more porous structure. However, at the same time, more thermal energy can be captured and concentrated at the surface of cement paste with the increasing amount of PVA, causing an increased thermal load and a negative effect on thermal insulating efficiency of cement paste. The contradictory effect of PVA on thermal properties of cement paste should be balanced before it is used as a foaming modifier to fabricate cementitious composites with thermal insulation. In addition, the contact angle measurement revealed that PVA can be used as an effective additive to improve the hydrophobicity of cement‐based materials. Only 3.0% PVA can turn the surface nature from hydrophilicity to hydrophobicity for cement paste, which benefited to the development of self‐cleaning cementitious composites. Finally, the mechanical properties of the PVA‐modified cement paste, especially for the tensile strength that has been rarely reported, were investigated and correlated with its thermal and surface properties. Due to the compensative effects of irregular packing, formation of PVA films and microcracks, tensile strength of cement paste can be improved by 23.5% with a small scarifying of the compressive strength by adding 2.0% of PVA. In conclusion, the PVA‐modified cement‐based materials with lower thermal conductivity, hydrophobic surface nature and enhanced mechanical properties have a great potential to satisfy the high requirements in developing sustainable infrastructure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46177.
Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali‐Ion Batteries
Authors: Das Suman , Swain Diptikanta , Araujo Rafael B. , Shi Songxin , Ahuja Rajeev , Row Tayur N. Guru , Bhattacharyya Aninda J.
Published: December 2017

We discuss here a unique flexible non‐carbonaceous layered host, namely, metal titanium niobates (M‐Ti‐niobate, M: Al3+, Pb2+, Sb3+, Ba2+, Mg2+), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M‐Ti‐niobate is formed by ion exchange of the K+ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO6 and NbO6 octahedral units in the sol‐gel synthesized potassium titanium niobate (KTiNbO5). Drastic volume changes (approximately 300–400 %) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M‐Ti‐niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50–75 % of total K+) in the M‐Ti‐niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M‐Ti‐niobate can be cycled over a wide voltage range (as low as 0.01 V) and displays remarkably stable Li+ and Na+ ion cyclability (>2 Li+/Na+ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al‐titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M‐Ti‐niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries.
High Crystalline Prussian White Nanocubes as a Promising Cathode for Sodium‐ion Batteries
Authors: Li Cong , Zang Rui , Li Pengxin , Man Zengming , Wang Shijian , Li Xuemei , Wu Yuhan , Liu Shuaishuai , Wang Guoxiu
Published: December 2017

Prussian blue and its analogues (PBAs) have been recognized as one of the most promising cathode materials for room‐temperature sodium‐ion batteries (SIBs). Herein, we report high crystalline and Na‐rich Prussian white Na2CoFe(CN)6 nanocubes synthesized by an optimized and facile co‐precipitation method. The influence of crystallinity and sodium content on the electrochemical properties was systematically investigated. The optimized Na2CoFe(CN)6 nanocubes exhibited an initial capacity of 151 mA h g−1, which is close to its theoretical capacity (170 mA h g−1). Meanwhile, the Na2CoFe(CN)6 cathode demonstrated an outstanding long‐term cycle performance, retaining 78 % of its initial capacity after 500 cycles. Furthermore, the Na2CoFe(CN)6 Prussian white nanocubes also achieved a superior rate capability (115 mA h g−1 at 400 mA g−1, 92 mA h g−1 at 800 mA g−1). The enhanced performances could be attributed to the robust crystal structure and rapid transport of Na ions through large channels in the open‐framework. Most noteworthy, the as‐prepared Na2CoFe(CN)6 nanocubes are not only low‐cost in raw materials but also contain a rich sodium content (1.87 Na ions per lattice unit cell), which will be favorable for full cell fabrication and large‐scale electric storage applications.
Boundary Control for a Flexible Inverted Pendulum System Based on a PDE Model with Input Saturation
Authors: Peng Yawei , Liu Jinkun
Published: December 2017

This research considers the control problem of a flexible inverted pendulum system (FIPS) in the presence of input saturation. The model for a flexible inverted pendulum system (FIPS) is derived via the Hamilton principle. The FIPS model is divided into a fast subsystem and a slow subsystem via the singular perturbation method. We introduce an auxiliary system to deal with the input saturation of a fast subsystem. To stabilize the fast subsystem, a boundary anti‐windup control force is applied at the free end of the beam. It is proven that the closed‐loop subsystem is stable. For the slow subsystem, a sliding mode control method is employed to design a controller and a new decoupling method to design the sliding surface. Then it is shown that the slow subsystem is stable. Finally, simulation results are provided to confirm the efficacy of the proposed controller.
Imputation for multisource data with comparison and assessment techniques
Authors: Casleton Emily , Osthus Dave , Van Buren Kendra
Published: December 2017

Missing data are prevalent issue in analyses involving data collection. The problem of missing data is exacerbated for multisource analysis, where data from multiple sensors are combined to arrive at a single conclusion. In this scenario, it is more likely to occur and can lead to discarding a large amount of data collected; however, the information from observed sensors can be leveraged to estimate those values not observed. We propose two methods for imputation of multisource data, both of which take advantage of potential correlation between data from different sensors, through ridge regression and a state‐space model. These methods, as well as the common median imputation, are applied to data collected from a variety of sensors monitoring an experimental facility. Performance of imputation methods is compared with the mean absolute deviation; however, rather than using this metric to solely rank the methods, we also propose an approach to identify significant differences. Imputation techniques will also be assessed by their ability to produce appropriate confidence intervals, through coverage and length, around the imputed values. Finally, performance of imputed datasets is compared with a marginalized dataset through a weighted k‐means clustering. In general, we found that imputation through a dynamic linear model tended to be the most accurate and to produce the most precise confidence intervals, and that imputing the missing values and down weighting them with respect to observed values in the analysis led to the most accurate performance. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.
Digital gestützte Bewehrungsabnahme als Beitrag zur Qualitätssicherung auf Baustellen
Authors: Klemt‐Albert Katharina , Ostermann Jörn , Munderloh Marco , Bahlau Sascha
Published: December 2017

Die Verknüpfung von Methoden des maschinellen Sehens mit digitalen Bauwerksmodellen kann einen deutlichen Beitrag zur Bauwerksqualität liefern, indem entscheidende Schritte im Qualitätssicherungsprozess teilautomatisiert werden können. Hierfür wird ein algorithmusbasierter virtueller Soll‐Ist‐Vergleich zwischen geforderter Bauwerksqualität und gebauter Realität unter Berücksichtigung zulässiger baulicher Toleranzen und technischer Regelungen entwickelt und am Beispiel der fotogrammetrischen Bewehrungsabnahme als Optimierungsansatz für die Qualitätssicherung auf Baustellen aufgesetzt. Kern des Ansatzes ist die (teil‐)automatische Verifikation der Objekte des digitalen Bauwerksmodells mittels Methoden des maschinellen Sehens (Computer Vision). Das gesamte Verfahren soll rein optisch ohne Marker und Referenzen erfolgen. Eine Herausforderung hierbei ist die Berücksichtigung der mehrstufigen Ausführungstoleranzen im Bauwesen. Mit der Umsetzung des vorgestellten Ansatzes kann die örtliche Bauüberwachung durch den intelligenten und transparenten Einsatz von Bauwerksinformationsmodellen und digitalen Informations‐ und Kommunikationstechnologien optimiert und damit eine signifikante Qualitätssteigerung sowohl bei der Bauwerkserstellung als auch bei der Dokumentation erzielt werden.
Transmembrane Signal Transduction in Two‐Component Systems: Piston, Scissoring, or Helical Rotation?
Authors: Gushchin Ivan , Gordeliy Valentin
Published: December 2017

Allosteric and transmembrane (TM) signaling are among the major questions of structural biology. Here, we review and discuss signal transduction in four‐helical TM bundles, focusing on histidine kinases and chemoreceptors found in two‐component systems. Previously, piston, scissors, and helical rotation have been proposed as the mechanisms of TM signaling. We discuss theoretically possible conformational changes and examine the available experimental data, including the recent crystallographic structures of nitrate/nitrite sensor histidine kinase NarQ and phototaxis system NpSRII:NpHtrII. We show that TM helices can flex at multiple points and argue that the various conformational changes are not mutually exclusive, and often are observed concomitantly, throughout the TM domain or in its part. The piston and scissoring motions are the most prominent motions in the structures, but more research is needed for definitive conclusions.
Superior mesenteric artery syndrome: quality of life after laparoscopic duodenojejunostomy
Authors: Barkhatov Leonid , Tyukina Natalia , Fretland Åsmund A. , Røsok Bård I. , Kazaryan Airazat M. , Riis Rolf , Edwin Bjørn
Published: December 2017

Key Clinical Message

In this study, we present results after laparoscopic duodenojejunostomy for five patients with protracted superior mesenteric artery syndrome. The procedure can be performed with minimal perioperative risk and very short postoperative stay. It provides significant postoperative symptom relief for many patients with typical presentation of the syndrome.
TiO2/Carbon Materials Derived from Hydrothermal Carbonization of Waste Biomass: A Highly Efficient, Low‐Cost Visible‐Light‐Driven Photocatalyst
Authors: Donar Yusuf Osman , Bilge Selva , Sınağ Ali , Pliekhov Oleksii
Published: December 2017

In this paper, we present a green, low‐cost carbon material derived from waste biomass (hazelnut shell (HS) and olive residue (OR)) to fabricate a binary TiO2/carbon composite for improving the photocatalytic performance of TiO2 under visible light. The synthesis, characterization, and photocatalytic applications of the TiO2/carbon composite were performed. Hydrothermal carbonization was used to obtain the carbon support materials. A series of TiO2/carbon composite materials from waste biomass based on hydrochar, fullerene, and carbon nanotubes has been prepared for comparison purposes. Photocatalytic performances of all composites were measured by comparing methylene blue (MB) removal rates. The results show that waste biomass based hydrochar/TiO2 composites possessed superior visible‐light photocatalytic activity compared with high technology carbons/TiO2 composites such as fullerene and carbon nanotubes. The enhanced photodegradation capacity could be ascribed to the delocalized furanic conjugated system and functional groups of HS‐TiO2 and OR‐TiO2 composites.
Contribution of image processing for analyzing the cellular structure of cork
Authors: Lagorce‐Tachon Aurélie , Mairesse Fabrice , Karbowiak Thomas , Gougeon Régis D. , Bellat Jean‐Pierre , Sliwa Tadeusz , Simon Jean‐Marc
Published: December 2017

The alveolar structure of cork confers to this natural material specific physical properties such as low permeability to liquids and gases, advanced thermal and acoustic insulation, and high elasticity. In this paper, a morphological analysis of natural cork cells is presented including statistical distributions of structural quantities. These results were obtained from the study of scanning electron microscopy images of natural cork stoppers. After automation of the image processing analysis, the area and perimeter distributions were measured in different cork sections: axial, tangential, and radial. Perpendicular to the radial direction we also focused on growth rings, which are characterized by smaller cell sizes. This systematic image analysis offers new possibilities to investigate the material at the cell scale and provides useful statistical information about the cork structure.
ADVANCES IN STEEL STRUCTURES AND STEEL MATERIALS IN JAPAN
Authors: Kanno Ryoichi
Published: December 2017

There are around six hundred thousand buildings that are built every year in Japan, and approximately 40% of them are constructed using steel frames. This wide application of steel frames is largely because of the continuing technological advancements in structural steel systems and steel materials for meeting a variety of needs that have evolved in the market. In this paper, starting with an overview of steel buildings in Japan, some of the advanced steel materials such as high‐strength steels and seismic resistant steels are outlined with their backgrounds. Since the material advancements in Japan are largely motivated by frequent large earthquakes, the relations with seismic design are stressed throughout the paper.
FATIGUE LIFE ASSESSMENT OF WELDED COVER PLATE BY USING GLOBAL AND LOCAL APPROACHES
Authors: Lukačević Ivan , Fuštar Boris , Dujmović Darko
Published: December 2017

This paper presents the fatigue life assessment of a welded detail in an existing steel railway bridge. The fatigue life is assessed based on strain measurements due to the passage of characteristic trains. Characteristic trains are an integral part of the load model formed by „Croatian railways„ data. Strain gauges that measure deformations are set at specific locations in order to gain information on Nominal and Hot Spot stresses. Based on this measurement data, stress ranges and stress spectrum are determined and compared to a corresponding detail category. Obtained results in this paper are related to comparing fatigue life of the analysed detail based on local and global approaches according to Eurocode 3 and IIW recommendations.
MODELING OF SMART PATCH/LAYER JOINTS UNDER DYNAMIC TIME HARMONIC LOAD WITH INTERFACE DEFECT
Authors: Petrova Tatyana S. , Becker Wilfried , Kirilova Elisaveta G. , Ivanova Jordanka A.
Published: December 2017

The modified 1D shear lag analysis is applied to study the hygro‐thermal‐piezoelectric response of a smart patch/layer structure with and without an interface gap along the overlap zone at environmental conditions and under dynamic time harmonic and electrical loads. The overlap zone is divided into 3 parts – 2 of them belong to intact parts of the interface and 1 of them to the length of the gap. All three types of closed form analytical solutions are derived and obtained. The comparison of the model shear stress, electric gradient, stresses and debond length for both cases of the interface (continuous or with a gap) is done at an example of a PZT‐5H/CFRP structure. All results are shown in figures and discussed.
SEISMIC PERFORMANCE OF STEEL MOMENT FRAME OFFICE BUILDINGS WITH RECTANGULAR CONCRETE‐FILLED STEEL TUBE GRAVITY COLUMNS
Authors: Pakwan Nipun , Judd Johnn
Published: December 2017

In conventional seismic design, the lateral strength in the gravity framing systems is not utilized. However, utilizing the lateral strength of a concrete‐filled steel tube (CFT) gravity column system has the potential to increase lateral capacity and improve global behaviour, compared to buildings with wide‐flange gravity columns. In this paper, the seismic performance of 1‐story, 2‐story and 4‐story office buildings with perimeter steel moment frames and gravity columns consisting of rectangular CFTs or wide flange members is evaluated. The results predicted that the CFTs generally improve seismic performance of the buildings, with reduced repair costs and repair times, compared to buildings with wide‐flange gravity columns.
Structural behavior of full‐scale beam‐to‐girder joints having composite slab under gravity load
Authors: Arita Masaki , Kitaoka Satoshi , Kanno Ryoich , Hanya Koji
Published: December 2017

Composite beam‐to‐girder joints with fin‐plates have been widely used in non‐seismic regions and basic design models have been proposed in EC4 and other documents; however, there is insufficient experimental data to verify the proposed models or to provide rational parameters that complete the joint models. In this paper, experiments of two full‐scaled beam‐to‐girder joints with composite slab were conducted: one without contact plates and the other with them between the lower flanges. Simple models of moment‐rotation relations were then proposed based on EC4. The proposed models provided reasonable approximations to the test results.
Giant Glycosidase Inhibitors: First‐ and Second‐Generation Fullerodendrimers with a Dense Iminosugar Shell
Authors: Nierengarten Jean‐François , Schneider Jérémy P. , Trinh Thi Minh Nguyet , Joosten Antoine , Holler Michel , Lepage Mathieu L. , Bodlenner Anne , García‐Moreno M. Isabel , Ortiz Mellet Carmen , Compain Philippe
Published: December 2017

The multivalent effect in glycosidase inhibition is a new topic in glycoscience that has emerged a few years ago, with the discovery of neoglycoclusters displaying strong binding enhancements over the corresponding monovalent inhibitor. Iminosugar–fullerene conjugates with high valencies have been prepared from iminosugar‐terminated dendrons and a clickable fullerene hexa‐adduct scaffold. The simultaneous grafting of twelve dendrons allows for a very fast dendritic growth thus limiting the number of synthetic steps required to prepare compounds with a high number of peripheral units. The grafting of first‐ and second‐generation dendrons provided fullerodendrimers surrounded by 36 and 108 peripheral iminosugars, respectively. Inhibition studies have been carried out with a panel of glycosidases. In the particular case of Jack bean α‐mannosidase, the 108‐valent nanoconstruct displays inhibition in the nanomolar range and an additional binding enhancement of one order of magnitude when compared to the 36‐valent analogues.
3D Micropatterned All‐Flexible Microfluidic Platform for Microwave‐Assisted Flow Organic Synthesis
Authors: Hur Deniz , Say Mehmet G. , Diltemiz Sibel E. , Duman Fatma , Ersöz Arzu , Say Rıdvan
Published: December 2017

A large‐area, all‐flexible, microwaveable polydimethoxysilane microfluidic reactor was fabricated by using a 3D printing system. The sacrificial microchannels were printed on polydimethoxysilane substrates by a direct ink writing method using water‐soluble Pluronic F‐127 ink and then encapsulated between polydimethoxysilane layers. The structure of micron‐sized channels was analyzed by optical and electron microscopy techniques. The fabricated flexible microfluidic reactors were utilized for the acetylation of different amines under microwave irradiation to obtain acetamides in shorter reaction times and good yields by flow organic synthesis.
One‐Step Synthesis of Nb2O5/C/Nb2C (MXene) Composites and Their Use as Photocatalysts for Hydrogen Evolution
Authors: Su Tongming , Peng Rui , Hood Zachary D. , Naguib Michael , Ivanov Ilia N. , Keum Jong Kahk , Qin Zuzeng , Guo Zhanhu , Wu Zili
Published: December 2017

Hydrogen production through facile photocatalytic water splitting is regarded as a promising strategy to solve global energy problems. Transition‐metal carbides (MXenes) have recently drawn attention as potential co‐catalyst candidates for photocatalysts. Here, we report niobium pentoxide/carbon/niobium carbide (MXene) hybrid materials (Nb2O5/C/Nb2C) as photocatalysts for hydrogen evolution from water splitting. The Nb2O5/C/Nb2C composites were synthesized by one‐step CO2 oxidation of Nb2CTx. Nb2O5 grew homogeneously on Nb2C after mild oxidation, during which some amorphous carbon was also formed. With an optimized oxidation time of 1.0 h, Nb2O5/C/Nb2C showed the highest hydrogen generation rate (7.81 μmol h−1 gcat−1), a value that was four times higher than that of pure Nb2O5. The enhanced performance of Nb2O5/C/Nb2C was attributed to intimate contact between Nb2O5 and conductive Nb2C and the separation of photogenerated charge carriers at the Nb2O5/Nb2C interface; the results presented herein show that transition‐metal carbide are promising co‐catalysts for photocatalytic hydrogen production.
Compressive sensing‐based adaptive sparse predistorter design for power amplifier linearization
Authors: Yao Yao , Li Mingyu , Jin Yi , Jiang Weiliang , Wang Yifan , Zhu Mingdong , He Songbai
Published: December 2017

Greedy algorithms in the compressive sensing theory have been formed the essential method for pruning power amplifier (PA) behavioral models and digital predistorters (DPDs). However, the inherent batch mode of these algorithms limits their application in adaptive digital predistortion framework. In this paper, a powerful subspace pursuit greedy scheme combined with stochastic gradient descent adaptive algorithm is proposed to design a class of adaptive sparse DPDs. According to the given sparsity level, the proposed approach can obtain the sparse terms of DPDs and extract the corresponding coefficients adaptively. Performance improvement of the proposed method is validated by simulation results on the adaptive DPD excited by 15‐MHz 3‐carrier Long‐Term Evolution signals and 50‐MHz 16 amplitude/phase‐shift keying signals. Meanwhile, measurement results on a Doherty PA excited by 30‐MHz 3‐carrier Long‐Term Evolution signals are also performed to verify the advantage of the proposed approach. Simulation and experimental results show that proposed algorithm can efficiently construct the adaptive sparse DPD models with only a small number of parameters; both nonlinear distortions and memory effects in the PA can be almost completely removed. A comparison with the nonsparsity aware DPD techniques and batch mode compressive sensing pruning techniques has been demonstrated that the proposed method exhibit faster convergence, improving tracking capabilities and reduced computational complexity.
Enhancement of nuclear reaction rates in asymmetric binary ionic mixtures
Authors: Clérouin J. , Arnault P. , Desbiens N. , White A. , Ticknor C. , Kress J.D. , Collins L.A.
Published: December 2017

Using orbital‐free molecular dynamics simulations we study the structure and dynamics of increasingly asymmetric mixtures such as hydrogen–carbon, hydrogen–aluminium, hydrogen–copper, and hydrogen–silver. We show that, whereas the heavy component structure is close to an effective one‐component plasma (OCP), the light component appears more structured than the corresponding OCP. This effect is related to the crossover towards a Lorentz‐type diffusion triggered by strongly coupled, highly charged heavy ions, and witnessed by the change of temperature scaling laws of diffusion. This over‐correlation translates into an enhancement of nuclear reaction rates much higher than its classical OCP counterpart.
Max Planck and Albrecht Unsöld on plasma partition functions and lowering of ionization energy
Authors: Ebeling W.
Published: December 2017

We summarize the work devoted to plasma thermodynamics and ionization theory performed by two protagonists working at Kiel University: Max Planck and Albrecht Unsöld. First we show that Planck developed, in Kiel, the basis for describing the chemical equilibria between charged particles (ions) and formulated later, in Berlin, the first complete version of the theory of ionization equilibria in plasmas with a convergent partition function. Abrecht Unsöld studied, in Kiel, the influence of plasma density on the atomic partition function, investigating the electric microfield between the ions. He showed that this effect leads to a lowering of the ionization energy going with the cubic root of the density. Finally, we discuss briefly recent theoretical and experimental work on the ionization potential depression.
Accelerator‐driven high‐energy‐density physics: Status and chances
Authors: Ren J. , Maurer C. , Katrik P. , Lang P.M. , Golubev A.A. , Mintsev V. , Zhao Y. , Hoffmann D.H.H.
Published: December 2017

We review the development of high‐energy‐density physics (HEDP) driven by intense particle beams, and give an account of the current status and the anticipated developments in the near future. Since progress of this field is strongly coupled to the technical development of high‐current accelerators, we report on the recent results in specific areas of high‐current accelerators relevant to HEDP. These are related to dynamic vacuum problems and the activation of accelerator structural material by high‐current, high‐energy particle beams, and we give an example of dense plasma diagnostics with high‐energy protons. The reported results have been achieved at existing machines at the Gesellschaft für Schwerionenforschung (GSI‐Darmstadt), the Institute of Theoretical and Experimental Physics in Moscow (ITEP‐Moscow), and the Institute of Modern Physics (IMP‐Lanzhou), and they are relevant for facilities under construction such as the FAIR facility in Darmstadt and the High Intensity Accelerator Facility (HIAF) proposed in China.
Local structure in dense hydrogen at the liquid–liquid phase transition by coupled electron–ion Monte Carlo
Authors: Pierleoni Carlo , Holzmann Markus , Ceperley David M.
Published: December 2017

We present a study of the local structure of high‐pressure hydrogen around the liquid–liquid transition line based on results from the coupled electron–ion Monte Carlo method. We report results for the equation of state and for the radial distribution function between protons g(r) and results from a cluster analysis to detect the possible formation of stable molecular ions beyond the transition line as well as above the critical temperature. We discuss various estimates for the molecular fraction in both phases and show that, although the presence of ions is suggested by the form of the g(r), they are not stable against thermal fluctuations.
Amyloidosis diagnosed in cytology specimen of pleural effusion: A case report
Authors: Manur Rashmi , Lamzabi Ihab
Published: December 2017

Amyloidosis is a rare condition resulting from extracellular deposition of amyloid, a fibrillary material derived from various precursor proteins. Involvement of the pleura by amyloidosis is a rare but serious complication. Pleural amyloidosis is primarily diagnosed by identifying amyloid deposition by histology on pleural biopsy specimens. Hereby, we report a case of systemic amyloidosis where we were able to identify amyloid in a pleural effusion specimen sent for cytopathology evaluation. A 59‐year‐old male with newly diagnosed multiple myeloma and systemic amyloidosis underwent therapeutic thoracentesis. The H&E stained cell block sections revealed a single, less than one millimeter focus of waxy material surrounded by a rim of reactive mesothelial cells suspicious for amyloid deposit in a background of fibrin, lymphocytes, and reactive mesothelial cells. The focus stained salmon pink with Congo‐red special stain and showed apple‐green birefringence under polarized light. Our finding suggests that pleural involvement in patients with systemic amyloidosis can be identified on effusion specimens and avert the need for more invasive procedures like pleural or pulmonary parenchymal biopsies.
Homogenizing an urban habitat mosaic: arthropod diversity declines in New York City parks after Super Storm Sandy
Authors: Savage Amy M. , Youngsteadt Elsa , Ernst Andrew F. , Powers Shelby A. , Dunn Robert R. , Frank Steven D.
Published: December 2017

The frequency and intensity of hurricanes are increasing globally, and anthropogenic modifications in cities have created systems that may be particularly vulnerable to their negative effects. Organisms living in cities are exposed to variable levels of chronic environmental stress. However, whether chronic stress ameliorates or exacerbates the negative effects of hurricanes remains an open question. Here, we consider two hypotheses about the simultaneous consequences of acute disturbances from hurricanes and chronic stress from urbanization for the structure of urban arthropod communities. The tipping point hypothesis posits that organisms living in high stress habitats are less resilient than those in low stress habitats because they are living near the limits of their environmental tolerances; while the disturbance tolerance hypothesis posits that high stress habitats host organisms pre‐adapted for coping with disturbance, making them more resilient to the effects of storms. We used a before‐after‐control‐impact design in the street medians and city parks of Manhattan (New York City, New York, USA) to compare arthropod communities before and after Super Storm Sandy in sites that were flooded and unflooded during the storm. Our evidence supported the disturbance tolerance hypothesis. Significant compositional differences between street medians and city parks before the storm disappeared after the storm; similarly, unflooded city parks had significantly different arthropod composition while flooded sites were indistinguishable. These differences were driven by reduced occurrences and abundances of arthropods in city parks. Finally, those arthropod groups that were most tolerant to urban stress were also the most tolerant to flooding. Our results suggest that the species that survive in high stress environments are likely to be the ones that thrive in response to acute disturbance. As storms become increasingly common and extreme, this juxtaposition in responses to storm‐associated disturbance may lead to diversity loss in cities, potentially leading entire urban landscapes to mirror the reduced diversity of street medians.
Grazing alters net ecosystem C fluxes and the global warming potential of a subtropical pasture
Authors: Gomez‐Casanovas Nuria , DeLucia Nicholas J. , Bernacchi Carl J. , Boughton Elizabeth H. , Sparks Jed P. , Chamberlain Samuel D. , DeLucia Evan H.
Published: December 2017

The impact of grazing on C fluxes from pastures in subtropical and tropical regions and on the environment is uncertain, although these systems account for a substantial portion of global C storage. We investigated how cattle grazing influences net ecosystem CO2 and CH4 exchange in subtropical pastures using the eddy covariance technique. Measurements were made over several wet‐dry seasonal cycles in a grazed pasture, and in an adjacent pasture during the first three years of grazer exclusion. Grazing increased soil wetness but did not affect soil temperature. By removing aboveground biomass, grazing decreased ecosystem respiration (Reco) and gross primary productivity (GPP). As the decrease in Reco was larger than the reduction in GPP, grazing consistently increased the net CO2 sink strength of subtropical pastures (55, 219 and 187 more C/m2 in 2013, 2014, and 2015). Enteric ruminant fermentation and increased soil wetness due to grazers, increased total net ecosystem CH4 emissions in grazed relative to ungrazed pasture (27–80%). Unlike temperate, arid, and semiarid pastures, where differences in CH4 emissions between grazed and ungrazed pastures are mainly driven by enteric ruminant fermentation, our results showed that the effect of grazing on soil CH4 emissions can be greater than CH4 produced by cattle. Thus, our results suggest that the interactions between grazers and soil hydrology affecting soil CH4 emissions play an important role in determining the environmental impacts of this management practice in a subtropical pasture. Although grazing increased total net ecosystem CH4 emissions and removed aboveground biomass, it increased the net storage of C and decreased the global warming potential associated with C fluxes of pasture by increasing its net CO2 sink strength.
First signs of macroinvertebrate recovery following enhanced restoration of boreal streams used for timber floating
Authors: Pilotto Francesca , Nilsson Christer , Polvi Lina E. , McKie Brendan G.
Published: December 2017

Although ecological restoration generally succeeds in increasing physical heterogeneity, many projects fail to enhance biota. Researchers have suggested several possible explanations, including insufficient restoration intensity, or time‐lags in ecological responses that prevent detection of significant changes in short‐term monitoring programs. This study aims to evaluate whether benthic macroinvertebrate communities responded to an expanded set of stream restoration measures within a study period of one to five years after completion of the restoration project. We studied 10 forest streams in northern Sweden that were channelized in the past for timber floating. Managers subjected six of these streams to habitat restoration, on each of these we selected two reaches, located in close proximity but differing in restoration intensity. In “basic” restored reaches, the restoration managers broke up the channelized banks and returned cobbles and small boulders to the main channel. In “enhanced” restoration reaches, they added additional large wood and boulders to reaches previously subjected to basic restoration, and rehabilitated gravel beds. The remaining four streams were not restored, and thus represent the baseline impacted (channelized) condition. We surveyed stream benthic assemblages before the enhanced restoration (year 2010) and three times afterward between 2011 and 2015. Five years after restoration, macroinvertebrate assemblages at the enhanced restored reaches were more differentiated from channelized conditions than those at basic‐restored reaches. This reflected increased relative abundances of the insect orders Ephemeroptera and Trichoptera and the bivalve molluscs Sphaeriidae and decreased relative abundances of Chironomidae (Diptera). Analysis of functional traits provided further insights on the mechanistic explanations driving the recovery, e.g., indicating that the augmented channel retention capacity at enhanced restored reaches favored taxa adapted to slow flow conditions and more effectively retained passive aquatic dispersers. The increased restoration intensity in enhanced restored reaches has resulted in shifts in the composition of benthic macroinvertebrate assemblages, including increases in more sensitive taxa. These shifts became fully apparent five years after the enhanced restoration. Our results emphasize the value of longer‐term monitoring to assess ecological responses following restoration, and of undertaking additional restoration as a valuable management option for previously restored sites that failed to achieve biotic recovery.
Anthropogenic N deposition increases soil C storage by reducing the relative abundance of lignolytic fungi
Authors: Entwistle Elizabeth M. , Zak Donald R. , Argiroff William A.
Published: December 2017

Atmospheric nitrogen (N) deposition has increased dramatically since preindustrial times and continues to increase across many regions of the Earth. In temperate forests, this agent of global change has increased soil carbon (C) storage, but the mechanisms underlying this response are not understood. One long‐standing hypothesis proposed to explain the accumulation of soil C proposes that higher inorganic N availability may suppress both the activity and abundance of fungi that decay lignin and other polyphenols in soil. In field studies, elevated rates of N deposition have reduced the activity of enzymes mediating lignin decay, but a decline in the abundance of lignolytic fungi has not been definitively documented to date. Here, we tested the hypothesis that elevated rates of anthropogenic N deposition reduce the abundance of lignolytic fungi. We conducted a field experiment in which we compared fungal communities colonizing low‐lignin, high‐lignin, and wood substrates in a northern hardwood forest that is part of a long‐term N deposition experiment. We reasoned that if lignolytic fungi decline under experimental N deposition, this effect should be most evident among fungi colonizing high‐lignin and wood substrates. Using molecular approaches, we provide evidence that anthropogenic N deposition reduces the relative abundance of lignolytic fungi on both wood and a high‐lignin substrate. Furthermore, experimental N deposition increased total fungal abundance on a low‐lignin substrate, reduced fungal abundance on wood, and had no significant effect on fungal abundance on a high‐lignin substrate. We simultaneously examined these responses in the surrounding soil and forest floor, in which we did not observe significant reductions in the relative abundance of lignolytic fungi or in the size of the fungal community; however, we did detect a change in community composition in the forest floor that appears to be driven by a shift away from lignolytic fungi and towards cellulolytic fungi. Our results provide direct evidence that reductions in the abundance of lignolytic fungi are part of the mechanism by which anthropogenic N deposition increases soil C storage.
Mate limitation in sea lice infesting wild salmon hosts: the influence of parasite sex ratio and aggregation
Authors: Cox R. , Groner M. L. , Todd C. D. , Gettinby G. , Patanasatienkul T. , Revie C. W.
Published: December 2017

Mate limitation in dioecious parasite species has the potential to impact parasite population growth. Our focus of interest was the influence of parasite sex distribution among hosts on parasite reproduction and transmission dynamics for populations of ectoparasitic sea lice (Lepeophtheirus salmonis Krøyer) establishing on wild juvenile salmon hosts. The data included more than 139,000 out‐migrating juvenile pink salmon (Oncorhynchus gorbuscha (Walbaum)) and chum salmon (Oncorhynchus keta (Walbaum)) in British Columbia, Canada, sampled over nine years. For almost all years, the sex ratio of the reproductive stages of the sea lice was female‐biased. The probability of a female being able to mate (i.e., of being attached to a fish also carrying a male louse) increased with increasing parasite abundance and parasite aggregation. We compared, with expected modeling predictions, the observed prevalence of pairs of sea lice (i.e., one reproductive louse of each sex) on a given fish and the observed probability of a female being able to mate. These comparisons showed that male and female sea lice tend to be distributed together rather than separately on hosts. Distribution together means that sea lice are distributed randomly on hosts according to a common negative binomial distribution, whereas distribution separately means that males are distributed according to a negative binomial and females are distributed in their own negative binomial among hosts. Despite the tendency for distribution together we found that, in every year, at least 30% of reproductive female sea lice experience mate limitation. This Allee effect will result in submaximal rates of parasite reproduction at low parasite abundances and may limit parasite transmission. The work has important implications for salmon parasite management and the health both of captive farm salmon populations and migratory wild stocks. More broadly, these results demonstrate the potential impact of mate limitation as a constraint to the establishment and spread of wild ectoparasite populations.