1,893 research outputs found
Stabilization of porous glass reverse-osmosis membranes
Application of porous glass in form of capillary tubes for low capacity ion exchange in hyperfiltration experiments is discussed. Efficiency of desalination by process of reverse osmosis is described. Stabilization of porous glass membrane by presence of aluminum chloride is analyzed
An Overview of the Kauffman Firm Survey: Results From the 2004-2008 Data
Presents findings from longitudinal data on new businesses founded in 2004, including financing structure; products, services, and innovations; and characteristics of the owners. Examines indicators of growth and survival and effects of the recession
An Overview of the Kauffman Firm Survey: Results From the 2004-2007 Data
Based on surveys conducted over four years, provides an overview of trends among U.S. firms established in 2004 and the business and owner characteristics associated with survival and growth, including level of innovation, structure, and financing
Kondo Screening and Magnetic Ordering in Frustrated UNi4B
UNi4B exhibits unusual properties and, in particular, a unique
antiferromagnetic arrangement involving only 2/3 of the U sites. Based on the
low temperature behavior of this compound, we propose that the remaining 1/3 U
sites are nonmagnetic due to the Kondo effect. We derive a model in which the
coexistence of magnetic and nonmagnetic U sites is the consequence of the
competition between frustration of the crystallographic structure and
instability of the 5f moments.Comment: 4 pages, 2 figure
Anisotropic interactions opposing magnetocrystalline anisotropy in SrNiIrO
We report our investigation of the electronic and magnetic excitations of
SrNiIrO by resonant inelastic x-ray scattering at the Ir L edge.
The intra- electronic transitions are analyzed using an atomic model,
including spin-orbit coupling and trigonal distortion of the IrO
octahedron, confronted to {\it ab initio} quantum chemistry calculations. The
Ir spin-orbital entanglement is quantified and its implication on the magnetic
properties, in particular in inducing highly anisotropic magnetic interactions,
is highlighted. These are included in the spin-wave model proposed to account
for the dispersionless magnetic excitation that we observe at 90 meV. By
counterbalancing the strong Ni easy-plane anisotropy that manifests
itself at high temperature, the anisotropy of the interactions finally leads to
the remarkable easy-axis magnetism reported in this material at low
temperature
Inhomogeneous magnetism in the doped kagome lattice of LaCuO2.66
The hole-doped kagome lattice of Cu2+ ions in LaCuO2.66 was investigated by
nuclear quadrupole resonance (NQR), electron spin resonance (ESR), electrical
resistivity, bulk magnetization and specific heat measurements. For
temperatures above ~180 K, the spin and charge properties show an activated
behavior suggestive of a narrow-gap semiconductor. At lower temperatures, the
results indicate an insulating ground state which may or may not be charge
ordered. While the frustrated spins in remaining patches of the original kagome
lattice might not be directly detected here, the observation of coexisting
non-magnetic sites, free spins and frozen moments reveals an intrinsically
inhomogeneous magnetism. Numerical simulations of a 1/3-diluted kagome lattice
rationalize this magnetic state in terms of a heterogeneous distribution of
cluster sizes and morphologies near the site-percolation threshold
Hierarchical geometric frustration in La3Cu2VO9
The crystallographic structure and magnetic properties of the La3Cu2VO9 were
investigated by powder neutron diffraction and magnetization measurements. The
compound materializes geometric frustration at two spatial scales, within
clusters and between clusters, and at different temperature scales. It is shown
by exactly solving the hamiltonian spectrum that collective spins are formed on
each clusters at low temperature before inter-clusters coupling operates.Comment: 6 pages, 4 figures. HFM2006 proceeding pape
Crystal Symmetry Lowering in Chiral Multiferroic BaTaFeSiO observed by X-Ray Magnetic Scattering
Chiral multiferroic langasites have attracted attention due to their
doubly-chiral magnetic ground state within an enantiomorphic crystal. We report
on a detailed resonant soft X-ray diffraction study of the multiferroic
BaTaFeSiO at the Fe and oxygen edges. Below
() we observe the satellite reflections ,
, and where . The dependence of the scattering intensity on X-ray polarization and
azimuthal angle indicate that the odd harmonics are dominated by the
out-of-plane (-axis) magnetic dipole while the
originates from the electron density distortions accompanying magnetic order.
We observe dissimilar energy dependences of the diffraction intensity of the
purely magnetic odd-harmonic satellites at the Fe edge. Utilizing
first-principles calculations, we show that this is a consequence of the loss
of threefold crystal symmetry in the multiferroic phase
U.S. Energy Sector Cybersecurity: Hands-Off Approach or Effective Partnership?
Recent reporting has identified significant threats to the U.S. energy’s critical infrastructure from nation states and other groups through cyberspace. Efforts to improve the security and resilience of U.S. energy infrastructure relies upon voluntary partnerships between the U.S. Government and public and private energy infrastructure owners. This paper examines ideal Public-Private Partnership (PPP) characteristics and compares them to an actual PPP in the U.S. The results identify strengths of and challenges to efforts to secure U.S. energy infrastructure. The research was conducted through a combination of literature reviews and interviews with a sample of U.S-government and private-energy infrastructure representatives
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