bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and Dynamics of Cool Flare Loops Observed by the Interface Region Imaging Spectrograph
Authors: Mikuła K. , Heinzel P. , Liu W. , Berlicki A. 
Published: August 2017

Abstract
Flare loops were well observed with the Interface Region Imaging Spectrograph (IRIS) during the gradual phase of two solar flares on 2014 March 29 and 2015 June 22. Cool flare loops are visible in various spectral lines formed at chromospheric and transition-region temperatures and exhibit large downflows which correspond to the standard scenario. The principal aim of this work is to analyze the structure and dynamics of cool flare loops observed in Mg ii lines. Synthetic profiles of the Mg ii h line are computed using the classical cloud model and assuming a uniform background intensity. In this paper, we study novel IRIS NUV observations of such loops in Mg ii h and k lines and also show the behavior of hotter lines detected in the FUV channel. We obtained the spatial evolution of the velocities: near the loop top, the flow velocities are small and they are increasing toward the loop legs. Moreover, from slit-jaw image (SJI) movies, we observe some plasma upflows into the loops, which are also detectable in Mg ii spectra. The brightness of the loops systematically decreases with increasing flow velocity, and we ascribe this to the effect of Doppler dimming, which works for Mg ii lines. Emission profiles of Mg ii were found to be extremely broad, and we explain this through the large unresolved non-thermal motions.
Distortion of Magnetic Fields in a Starless Core: Near-infrared Polarimetry of FeSt 1–457
Authors: Kandori Ryo , Tamura Motohide , Kusakabe Nobuhiko , Nakajima Yasushi , Kwon Jungmi , Nagayama Takahiro , Nagata Tetsuya , Tomisaka Kohji , Tatematsu Ken’ichi 
Published: August 2017

Abstract
Magnetic fields are believed to play an important role in controlling the stability and contraction of the dense condensations of gas and dust that lead to the formation of stars and planetary systems. In the present study, the magnetic field of FeSt 1–457, a cold starless molecular cloud core, was mapped on the basis of the polarized near-infrared light from 185 background stars after being dichroically absorbed by dust aligned with the magnetic field in the core. A distinct “hourglass-shaped” magnetic field was identified in the region of the core, and was interpreted as the first evidence of a magnetic field structure distorted by mass condensation in a starless core. The steep curvature of the magnetic field lines obtained in the present study indicates that the distortion was mainly created during the formation phase of the dense core. The derived mass-to-magnetic flux ratio indicates that the core is in a magnetically supercritical state. However, the stability of the core can be considered to be in a nearly critical state if the additional contributions from the thermal and turbulent support are included. Further diffusion of the magnetic field and/or turbulent dissipation would cause the onset of the dynamical collapse of the core. The geometrical relationship between the direction of the magnetic field lines and the elongation of the core was found to be in good agreement with theoretical predictions for the formation of Sun-like stars under the influence of a magnetic field.
Monitor Variability of Millimeter Lines in IRC+10216
Authors: He 何 J. H. 金华 , Dinh-V-Trung  , Hasegawa T. I. 
Published: August 2017

Abstract
A single dish monitoring of millimeter maser lines SiS J = 14-13 and HCN

ν

2

=

1

f

J = 3-2 and several other rotational lines is reported for the archetypal carbon star IRC+10216. Relative line strength variations of 5% ∼ 30% are found for eight molecular line features with respect to selected reference lines. Definite line-shape variations are found in limited velocity intervals of the SiS and HCN line profiles. The asymmetrical line profiles of the two lines are mainly due to the varying components. The dominant varying components of the line profiles have similar periods and phases to the IR light variation, though both quantities show some degree of velocity dependence; there is also variability asymmetry between the blue and red line wings of both lines. Combining the velocities and amplitudes with a wind velocity model, we suggest that the line profile variations are due to SiS and HCN masing lines emanating from the wind acceleration zone. The possible link of the variabilities to thermal, dynamical, and/or chemical processes within or under this region is also discussed.
Suboxides and Other Low‐Valent Species
Authors: Simon Arndt 
Published: August 2017

AbstractSuboxides of the heavy alkali metals rubidium and cesium represent a unique class of metal‐rich compounds whose crystal structures contain characteristic clusters that are immersed in a matrix of pure metal. The structural principle extends to subnitrides of the alkaline earth metals exhibiting a rich chemistry of both discrete clusters in a metal matrix and condensed cluster systems.
Nitrides of Non‐Main Group Elements
Authors: Höhn P. , Niewa R. 
Published: August 2017

AbstractIn the last two decades, there has been a renewed interest in the chemistry of nitrides and nitridometalates. Both binary and higher nitridesMxNyhave already featured prominently as refractory materials, corrosion‐ and mechanical wear‐resistant coatings, hard materials, and hard magnets; thin films are used as diffusion barriers in integrated circuits.Whereas research on binary transition metal nitrides is mostly driven by technical and economic interests, the investigation on nitridometalates primarily focuses on exploration with respect to the development of new synthetic strategies and the design of new materials. Within this field of interest, especially the nitride chemistry of rare earth metals is still comparably undeveloped.Chemical bonding in binary nitrides varies from primarily salt‐like via covalent to metallic, whereas nitridometalates are best described as containing covalent complex anions [MxNy]z−with alkali, alkaline earth, or rare earth metal cations providing electroneutrality.
Metal Borides: Versatile Structures and Properties
Authors: Albert Barbara , Hofmann Kathrin 
Published: August 2017

AbstractBorides represent an important class of inorganic solids. Often they exhibit interesting properties and can be used either as structural and functional materials or as catalysts. Boron is a non‐metallic, light element with three valence electrons. Its ability to form multi‐centred bonds to overcome the electron deficiency is huge, and it manifests itself in an enormous variety of complicated structures. Many metals react with boron and form borides. Metal borides (MxBz, MxM′yBz, etc.; M, M′ = metals) are binary or multinary compounds in which boron is the most electronegative partner. The huge variety of boride structures is known. It is reasonable to distinguish between, on the one hand, the more metal‐rich borides in which boron atoms are either isolated or they form dumbbells or chains and, on the other side, the boron‐rich materials that display very exotic framework structures, often consisting of beautiful deltahedra. In between there are the layered structures with two‐dimensional arrays of boron atoms. The degree of dimensionality of the arrangement of the boron atoms correlates closely with the (non)metallic character of the borides. Thus, the structural diversity is reflected by an extreme variability of electrical properties between metallic and ceramic. The huge influence of the boron atom structure on the electronic structure of the metal borides is quite unique. It has its origin in the special electron‐deficient character of the boron atom that often leads to a very special bonding situation in boron compounds.
Molecular Magnets
Authors: Yakhmi J.V. 
Published: August 2017

AbstractThe well‐known magnetic materials used in present‐day technologies, such as, Fe, Fe2O3, Cr2O3, SmCo5, Nd2Fe14B, and so on, are all atom‐based. And due to this reason the preparation/processing of these conventional magnets requires energy consuming high temperature routes. In contrast, the new emerging molecule‐based magnetic materials exploit self‐assembly methods that play with weak intermolecular interactions to produce long‐range bulk magnetic order in them. The first successful synthesis of molecular magnets was made in 1986, and since then, a large variety of them have been synthesized, which can be categorized on the basis of the chemical nature of the magnetic units involved: organic, metal‐based systems, heterobimetallic assemblies, or mixed organic–inorganic systems, single molecule magnets, single chain magnets, and so on. Solubility, low density, and biocompatibility are attractive features of molecular magnets. Being weakly colored, unlike their opaque classical magnet “cousins” listed above, possibilities of photomagnetic switching exist. There have been attempts to design and synthesize polyfunctional molecular magnets, such as those exhibiting second‐order optical nonlinearity, liquid crystallinity, or chirality simultaneously with long‐range magnetic order. Efforts also continue to design the ever‐elusive polymer magnets toward applications in industry. While providing a brief overview of the field of molecular magnetism, this chapter aims to highlight a few recent developments in it, including from the author's own lab.
Solvothermal Methods
Authors: Kumada Nobuhiro 
Published: August 2017

Abstract

A solvothermal reaction is defined as a chemical reaction that occurs in an aqueous or nonaqueous solvent at high temperature and pressure in a closed system. The definition includes other reactions at high temperature and pressure such as a hydrothermal reaction using water, an ammonothermal one using ammonia, a glycothermal one using glycol, and an ionothermal one using an ionic liquid as solvent.
Chemical Patterning on Surfaces and in Bulk Gels
Authors: Karthaus Olaf 
Published: August 2017

AbstractChemical patterns can be defined as patterns on a substrate that exhibit a chemical contrast, or as patterns that are formed by a chemical reaction, either on a surface or in bulk. This chapter classifies the surface pattern in further subgroups, depending on their formation technique (top‐down or bottom‐up), and gives some applications for surface patterns. The bulk patterns described here, Liesegang rings, are formed by a chemical reaction in diffusing electrolyte solutions in a gel. This technique to prepare a pattern is quite old, but still poorly understood, and their formation mechanism controversial.
Mechanical Properties
Authors: Schnabel Volker , Baben Moritz to , Music Denis , Clegg William J. , Schneider Jochen M. 
Published: August 2017

Abstract

This chapter introduces mechanical properties of materials in a way accessible to the solid‐state chemist. It discusses elastic and plastic properties, fracture of materials, information on elastic and nonelastic behavior, as well as friction and wear on the atomic scale, the length scale most familiar to the solid‐state chemist. Different plastic deformation mechanisms exist and all of them can be related to defects. The chapter then focuses on dislocation movement since it is the most common plastic deformation mechanism. An edge dislocation is characterized by a line vector L describing the border of the inserted half‐plane and the Burgers vector b describing the lattice distortion. The Burgers vector is constructed by following a continuous path around the dislocation with arbitrary distance from the dislocation core. Finally, the chapter describes experimental techniques enabling the characterization of mechanical properties.
Zeolite and Zeolite‐Like Materials
Authors: Chaikittisilp Watcharop , Okubo Tatsuya 
Published: August 2017

AbstractZeolites are crystalline microporous aluminosilicates that are constructed from corner‐sharing, tetrahedrally coordinatedTO4/2primary units (where T is a tetrahedral atom – silicon or aluminum). Thanks to their unique crystalline framework structures, well‐defined channels and cavities in a nanometer length scale, high surface areas, and several intrinsic properties arising from their anionic nature, zeolites have been widely used in various practical applications as adsorbents, ion exchangers, and catalysts. Zeolites have found their solid positions as key materials in industries and will continue to be the dominant industrial materials in future. Following a brief description of zeolite framework structures, in this chapter, the historical, fundamental, and recent aspects of zeolite synthesis are described. In addition, future prospects of zeolite toward the sustainable development are addressed.
Metal–Organic Frameworks: An Emerging Class of Solid‐State Materials
Authors: Mondloch Joseph E. , Klet Rachel C. , Howarth Ashlee J. , Hupp Joseph T. , Farha Omar K. 
Published: August 2017

Abstract

Metal–organic frameworks (
MOFs
) are built up from inorganic nodes (metal ions or polymetallic clusters) and multitopic organic linkers. Given that both of these components can be readily tuned, thousands of examples of
MOFs
have been prepared to date. In many instances
MOFs
are crystalline and highly porous that has driven researchers to investigate these materials for a handful of practical applications. In this chapter we give a brief overview of this emerging class of solid‐state materials. Along the way we highlight: the synthetic tools used to prepare
MOFs
; strategies used to activate (remove guest molecules from their pores)
MOFs
; several criteria for designing more robust
MOFs
; and several examples of where
MOFs
are being considered as solutions for practical applications.
Eliminating Core Electrons in Electronic Structure Calculations: Pseudopotentials andPAWPotentials
Authors: Goedecker Stefan , Saha Santanu 
Published: August 2017

AbstractPseudopotentials andPAWmethods are an important and widely used tool for the calculation of electronic and structural properties of all kinds of condensed matter systems such as molecules, clusters, surfaces, and solids. This chapter will introduce the basic concepts and discuss their accuracy as well as the interplay between their functional form and numerical efficiency.
Many Body Perturbation Theory, Dynamical Mean Field Theory and All That
Authors: Biermann Silke , Lichtenstein Alexander 
Published: August 2017

AbstractThis chapter gives an introduction to the theoretical description of strongly correlated materials from first principles. Recent progress in the numerical solution of effective quantum impurity problems within continuous‐time Quantum Monte Carlo schemes has opened the way to efficient dynamical mean field theory‐based simulations of finite‐temperature properties of correlated solids. Here, we review the combinations of dynamical mean‐field theory (DMFT) with density functional theory (DFT) or first‐order many‐body perturbation theory (the so‐called “GW approximation”) from a general functional formulation point of view, putting them into perspective with dual fermion and boson approaches. The goal of these theoretical constructions is to retain the many‐body aspects of local atomic physics within the extended solid. We will describe the current state‐of‐the‐art and future challenges.
Spin Polarization
Authors: Seo Dong‐Kyun 
Published: August 2017

AbstractSpin polarization in electronic systems is a fundamental phenomenon associated with electron–electron interactions. An open‐shell atom in its ground state exhibits unpaired electrons and hence carries a magnetic moment through spin polarization in valence orbitals. In a simplistic view, the magnetic moments would be aligned in parallel among neighboring atoms to maximize the lowering of the electron–election repulsion by taking advantage of the Pauli exclusion principle. However, energy lowering by chemical bond formation or electron delocalization favors double electron occupancy of bonding (delocalized) orbitals, leading to an antiparallel spin alignment or even to a spin unpolarized electronic structure. Observation of various magnetic behaviors indicates that neither of two competing effects is always dominant in molecules and solids. Challenge in understanding the competition and its consequence, especially in solid‐state compounds, is twofold. First, there exist diverse magnetic compounds that seemingly require different conceptual starting points to apprehend their properties. Second, different models for different types of the magnetism have been incoherent with disparate degrees of approximations and sophistications. This chapter is intended to examine those traditional models and to provide a unified conceptual model, under the name of “spin polarization perturbational orbital theory (SPPOT)” (Kübler, J.K. (2000)Theory of Itinerant Electron Magnetism, Clarendon Press/Oxford University Press, Oxford; Seo, D.K. (2006) Density functional perturbational orbital theory of spin polarization in electronic systems. I. Formalism.J. Chem. Phys.,125(15), 154105), in understanding the spin polarization phenomenon within the framework of Kohn–Sham spinpolarized density functional theory (KS‐SDFT).
Tight‐Binding Density Functional Theory:DFTB
Authors: Seifert Gotthard 
Published: August 2017

AbstractA review of the foundations of the density functional theory based tight binding is given. The relation to the density functional theory as formulated by Hohenberg and Kohn is briefly sketched. The approximations that make it compatible with a tight‐binding representation are described and discussed. These approximations are densities and potentials are written as superpositions of atomic densities and potentials and many‐center terms are summarized together with nuclear repulsion energy terms in a way that they can be written as sum of pairwise repulsive terms. For small distances the nuclear repulsion dominates, whereas for large distances these terms vanish. The Kohn–Sham orbitals are expanded in a set of localized atom‐centered functions. They are represented in a minimal basis of optimized atomic orbitals of neutral atoms. The approximations lead to Hamilton and overlap matrices with only one‐ and two‐center contributions. Also, the self‐consistent charge extension, the treatment of weak interactions periodic boundary conditions, and linear response scheme for the calculation of optical properties are explained. The potential of “order‐N” treatments is critically discussed. Finally, some practical aspects, the limitations, and an outlook for improvements are presented.
Superhard Materials
Authors: Riedel Ralf , Wiehl Leonore , Zerr Andreas , Zinin Pavel , Kroll Peter 
Published: August 2017

Abstract
The search for superhard materials is motivated by technical applications under extreme conditions. The term "superhard" usually denotes materials with Vickers hardness (HV) larger than 40 GPa. This chapter presents some classes of hardest compounds, and concentrates on novel nitrides and some carbides and carbonitrides. It summarizes the latest developments in modeling and synthesis as well as potential properties of advanced materials with super‐ and ultrahard mechanical properties. The chapter presents a short overview of hardness and elastic properties. The elastic properties of an isotropic homogeneous solid can be described by any two of the four quantities: Young's modulus, shear (or rigidity) modulus, bulk modulus, Poisson's ratio. The process of hardness determination involves various mechanisms, among which are volume compression, shear deformation, bond breaking, and creation and motion of dislocations. The phenomenological correlations between hardness and elastic properties of a material serve excellently to estimate hardness of a single crystal.
Functional Surfaces for Biomaterials
Authors: Nagai Akiko , Horiuchi Naohiro , Nakamura Miho , Wada Norio , Yamashita Kimihiro 
Published: August 2017

Abstract
Material surfaces and biological systems form interfaces that are metastable and change depending on circumstances. The preferable properties of the biomaterial surface are described by the term of biocompatibility. However, the desirable properties vary widely depending on the applications. Surface chemistry, surface topology, mechanical properties, and electric properties are representative key factors involved in the surface properties of biomaterials. This chapter focuses especially on electric properties of the biomaterials. Hydroxyapatite, the most well‐known inorganic biomaterial, can be electrically polarized by an electrical procedure. The surface properties, the wettability, and surface free energy, are changed by the polarization, and the polarization influences cultured cell behavior and biomimetic crystallization processes on the surfaces.
Activity of Zeolitic Catalysts
Authors: Meng Xiangju , Wang Liang , Xiao Feng‐Shou 
Published: August 2017

Abstract
Approximately nine‐out‐of‐ten chemical processes worldwide utilize heterogeneous catalysts currently, where selectivity for the shape/size of the reactant, product or intermediate together with stability are the vital aspects. Combination of selectivity and stability for zeolites offers unique structural and chemical features that can be beneficial for many commercially important reactions/processes. Typically, the introduction of zeolites into refinery operations has been revolutionary as it resulted in a significant increase in gasoline yield from catalytic cracking; zeolite catalysts are selective for the formation of light olefins from methanol and syngas and the production of chemicals and fuels for renewable carbon sources; the applications of zeolite catalysts for environmental protection offer good opportunities to develop selective catalytic reduction of harmful gases. In this chapter, an overview of the current and potential applications of zeolites as catalysts in academic and commercially important chemical industry reactions/processes is summarized.
Molecular dynamics study on the Apo‐ and Holo‐forms of 5‐lipoxygenase
Authors: Torras Juan , Maccarrone Mauro , Dainese Enrico 
Published: August 2017

AbstractLipoxygenases (LOXs) are nonheme iron‐containing enzymes catalyzing the dioxygenation of polyunsaturated fatty acids. LOX catalytic activity depends on the presence of iron in the active site and the iron removal is also able to affect the membrane binding properties of the enzyme. Leukotrienes biosynthesis is initiated by the action of 5‐LOX at the level of nuclear membrane and the mechanism of enzyme–membrane interaction is thought to involve structural flexibility and conformational changes at the level of the protein tertiary structure. In this study, we have analyzed by molecular dynamics simulations the conformational changes induced by iron removal in 5‐LOX. The data indicate that the degree of enzyme flexibility is related to the presence of iron into the active site that is able to stabilize the protein increasing its rigidity. These findings provide further evidence that the conformation and the functional activity of LOXs is tuned by the presence of iron at the active site, suggesting new approaches for the design of enzyme inhibitors.