3,821 research outputs found

    The 4-Nitro-5-Methyl-2-Sulphobenzoic Acid and Some of Its Derivatives

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    The 4-nitro-5-methyl-2-sulphobenzoic acid has been investigated to a limited extent as one of the products formed when the 6-nitro-1, 3-dimethyl-4-sulphonic acid is oxidized by potassium permanganate in dilute alkaline solution. Previous to this research, the only record of its preparation was by Limpricht, in which case only a small amount of the neutral potassium salt was isolated. He gives this as occurring with one-half a molecule of water of crystallization, but does not state which of the two methyl groups of the original acid had been oxidized. The neutral potassium salt does not seem to contain any water of crystallization, however, and some doubt is cast upon the value of the observation as made by him

    Direct Evidence for the Source of Reported Magnetic Behavior in "CoTe"

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    In order to unambiguously identify the source of magnetism reported in recent studies of the Co-Te system, two sets of high-quality, epitaxial CoTex_x films (thickness ≃\simeq 300 nm) were prepared by pulse laser deposition (PLD). X-ray diffraction (XRD) shows that all of the films are epitaxial along the [001] direction and have the hexagonal NiAs structure. There is no indication of any second phase metallic Co peaks (either fccfcc or hcphcp) in the XRD patterns. The two sets of CoTex_x films were grown on various substrates with PLD targets having Co:Te in the atomic ratio of 50:50 and 35:65. From the measured lattice parameters c=5.396A˚c = 5.396 \AA for the former and c=5.402A˚c = 5.402\AA for the latter, the compositions CoTe1.71_{1.71} (63.1% Te) and CoTe1.76_{1.76} (63.8% Te), respectively, are assigned to the principal phase. Although XRD shows no trace of metallic Co second phase, the magnetic measurements do show a ferromagnetic contribution for both sets of films with the saturation magnetization values for the CoTe1.71_{1.71} films being approximately four times the values for the CoTe1.76_{1.76} films. 59^{59}Co spin-echo nuclear magnetic resonance (NMR) clearly shows the existence of metallic Co inclusions in the films. The source of weak ferromagnetism reported in several recent studies is due to the presence of metallic Co, since the stoichiometric composition "CoTe" does not exist.Comment: 19 pages, 7 figure

    Ab Initio Evidence for the Formation of Impurity d(3z^2-r^2) Holes in Doped La_{2-x}Sr_xCuO_4

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    Using the spin unrestricted Becke-3-Lee-Yang-Parr density functional, we computed the electronic structure of explicitly doped La_{2-x}Sr_xCuO_4 (x = 0.125, 0.25, and 0.5). At each doping level, an impurity hole band is formed within the undoped insulating gap. This band is well-localized to CuO_6 octahedra adjacent to the Sr impurities. The nature of the impurity hole is A_{1g} in symmetry, formed primarily from the z^2 orbital on the Cu and p_z orbitals on the apical O's. There is a strong triplet coupling of this hole with the intrinsic B_{1g} Cu x^2-y^2/O1 p_{sigma} hole on the same site. Optimization of the c coordinate of the apical O's in the doped CuO_6 octahedron lead to an asymmetric anti-Jahn-Teller distortion of the O2 atoms toward the central Cu. In particular, the O2 atom between the Cu and Sr is displaced 0.26 A while the O2 atom between the Cu and La is displaced 0.10 A. Contrary to expectations, investigation of a 0.1 A enhanced Jahn-Teller distortion of this octahedron does not force formation of an x^2-y^2 hole, but instead leads to migration of the z^2 hole to the four other CuO_6 octahedra surrounding the Sr impurity. This latter observation offers a simple explanation for the bifurcation of the Sr-O2 distance revealed in x-ray absorption fine structure data.Comment: Submitted to Phys. Rev. B. See http://www.firstprinciples.com for more informatio

    Ordovician Stratigraphy and the Physiography of Part of Southeastern Indiana

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    Indiana Geological Survey Guidebook 6This field trip guidebook discusses the stratigraphy and paleontology of the Ordovician rocks exposed in southeastern Indiana. Ordovician rocks in southern Indiana are exposed in a region that is stimulating to physiographers and Pleistocene geologist. Consequently, in addition to the stratigraphy and paleontology of the Ordovician bedrock, this conference directs attention to prominent physiographic features in this area, many of which owe their origin to Pleistocene glaciation, and to concepts regarding their development. Ordovician rocks in southern Indiana are paleontologically attractive because they are so richly fossiliferous. Well-preserved specimens maybe readily collected in weathered exposures and in the soft shales of the Cincinnatian (Upper Ordovician) series. Southeastern Indiana has not yielded mineral commodities as plentifully as other parts of the state. Nevertheless, two stops and several observation points along the route of the caravan draw attention to some of the industrial minerals found in this area. This conference is designed to present as coherent a view as time will permit of the geology of southeastern Indiana. The stops have been carefully selected to show features of stratigraphic, paleontologic, physiographic, or economic interest. Informal discussion among participants will contribute greatly to the success of the conference.Department of Geology, Indiana University; Indiana Geological Survey; Indiana Department of Conservatio

    Ordovician Stratigraphy, and the Physiography of Part of Southeastern Indiana

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    Within recent years field conferences sponsored by the Geological Survey, Indiana Department of Conservation, and the Department of Geology, Indiana University, have reviewed outstanding exposures and of parts of the Silurian, Devonian, Mississippian, and Pennsylvanian systems in southern Indiana. This conference is concerned, in part, with the stratigraphy and paleontology of the Ordovician rocks exposed in southeastern Indiana

    Strength Prediction Model for Power Acutated Fasteners Connecting Steel Members in Tension and Shear-north American Applications

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    Power-actuated fasteners (PAFs), also referred to as pins, are small nail-like or threaded stud t ype connectors. They can be used in conjunction with several materials and in a number of different applications. Typical applications in steel include attachments of deck sh eeting or diaphragms, architectural or mechanical components, or miscellaneous support brackets or connections to supporting steel members. Traditionally, the design strength of the connections featuring power-actuated fasteners has been determined through standardized testing protocols. In the United States, this protocol is embodied in the American Society for Testing and Materials (ASTM) Standard E 1190. The purpose of this study was to create a generic strength prediction model for pins embedded in steel substrate and subjected to either shear or tension, and to present the equations in a limit states fo rmat applicable to the North American practice and applications

    Rocks Associated With the Mississippian-Pennsylvanian Unconformity in Southwestern Indiana

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    The purpose of this field conference is to acquaint participants with strata that are associated with the Mississippian-Pennsylvanian unconformity in southwestern Indiana. Criteria which aid in distinguishing between Mansfield strata of Pottsville (early Pennsylvanian) age and classic formations of Chester (late Mississippian) age will receive considerable attention in discussions at evening meetings and on the outcrop. Inspection of limestone and sandstone quarries will afford an insight into the economic products of Chester and Mansfield rocks

    Ariel - Volume 8 Number 1

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    Executive Editor James W. Lockard, Jr. Issue Editor Michael J. Grimes Business Manager Neeraj K. Kanwal Managing Editor Edward H. Jasper University News Richard J. Perry World News William D.B. Hiller Opinions Elizabeth A. McGuire Features Patrick P. Sokas Sports Desk Shahab S. Minassian Managing Associate Brenda Peterson Photography Robert D. Lehman, Jr. Graphics Christine M. Kuhnl

    Lattice QCD Constraints on the Fourth Mellin Moment of the Pion Light Cone Distribution Amplitude using the HOPE method

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    The light-cone distribution amplitude (LCDA) of the pion contains information about the parton momentum carried by the quarks and is an important theoretical input for various predictions of exclusive processes at high energy, including the pion electromagnetic form factor. Progress towards constraining the fourth Mellin moment of the LCDA using the heavy-quark operator product expansion (HOPE) method is presented.Comment: 10 pages, 4 figures, proceedings to talk presented at the 40th International Symposium on Lattice Field Theory, July 31st - August 4th 2023, Fermi National Accelerator Laboratory, Batavia, Illinois, USA. arXiv admin note: text overlap with arXiv:2211.1700

    Quantum phase space picture of Bose-Einstein Condensates in a double well: Proposals for creating macroscopic quantum superposition states and a study of quantum chaos

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    We present a quantum phase space model of Bose-Einstein condensate (BEC) in a double well potential. In a two-mode Fock-state analysis we examine the eigenvectors and eigenvalues and find that the energy correlation diagram indicates a transition from a delocalized to a fragmented regime. Phase space information is extracted from the stationary quantum states using the Husimi distribution function. It is shown that the quantum states are localized on the known classical phase space orbits of a nonrigid physical pendulum, and thus the novel phase space characteristics of a nonrigid physical pendulum such as the π\pi motions are seen to be a property of the exact quantum states. Low lying states are harmonic oscillator like libration states while the higher lying states are Schr\"odinger cat-like superpositions of two pendulum rotor states. To study the dynamics in phase space, a comparison is made between a displaced quantum wavepacket and the trajectories of a swarm of points in classical phase space. For a driven double well, it is shown that the classical chaotic dynamics is manifest in the dynamics of the quantum states pictured using the Husimi distribution. Phase space analogy also suggests that a π\pi phase displaced wavepacket put on the unstable fixed point on a separatrix will bifurcate to create a superposition of two pendulum rotor states - a Schr\"odinger cat state (number entangled state) for BEC. It is shown that the choice of initial barrier height and ramping, following a π\pi phase imprinting on the condensate, can be used to generate controlled entangled number states with tunable extremity and sharpness.Comment: revised version, 13 pages, 13 figure
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