3,821 research outputs found
The 4-Nitro-5-Methyl-2-Sulphobenzoic Acid and Some of Its Derivatives
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"
In order to unambiguously identify the source of magnetism reported in recent
studies of the Co-Te system, two sets of high-quality, epitaxial CoTe films
(thickness 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 or ) in the XRD
patterns. The two sets of CoTe 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 for the former and
for the latter, the compositions CoTe (63.1% Te) and CoTe
(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 CoTe films being approximately four times
the values for the CoTe films. 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
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
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
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
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
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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Christine M. Kuhnl
Lattice QCD Constraints on the Fourth Mellin Moment of the Pion Light Cone Distribution Amplitude using the HOPE method
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
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 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
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 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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