The 1:1 molecular adduct of propylene oxide and water (PO-H(2)O) was studied using Fourier transform microwave spectroscopy and high level ab initio methods. Two distinct structural conformers with the water molecule acting as a proton donor were detected experimentally: one with the water on the same side as the methyl group with respect to the ether ring, i.e., syn-PO-H(2)O, the other with the water molecule binding to the O-atom from the opposite side of the methyl group, i.e., anti-PO-H(2)O. The nonbonded hydrogen is entgegen to the ether ring in both conformers. Rotational spectra of four isotopic species, namely PO-H(2)O, PO-DOH, PO-HOD, and PO-D(2)O, were recorded for the two conformers. The hydrogen bond parameters: r(O(epoxy)...H), angle(ring-O(epoxy)...H), and angle(O(epoxy)...H-O) are 1.908 A, 112 degrees, and 177 degrees for syn-PO-H(2)O, and 1.885 A, 104.3 degrees, and 161.7 degrees for anti-PO-H(2)O, respectively. The experimental results suggest that the hydrogen bond in syn-PO-H(2)O is stronger and the monomer subunits are more rigidly locked in their positions than in the ethylene oxide-water adduct. The stabilizing effect of the methyl group to the intermolecular hydrogen bond is discussed in terms of the experimentally estimated binding energies, the structural parameters, and the ab initio calculations.

Microwave-assisted magnetization switching was investigated using Fe30Co70∕AlOx∕Ni80Fe20 magnetic tunnel junctions incorporated with a coplanar waveguide. Coercivity field of Ni80Fe20 layer was dramatically reduced in a small amplitude microwave. The authors eliminated the thermal effect in coercivity reduction by comparing two types of measurements which are with and without spin precession in the presence of microwave. It was found that the coercivity reduction depends on both frequency and power of the microwave. The numerical simulation based on Landau-Lifshitz-Gilbert equation reproduced the trend of the experimental data. The results indicate that microwave can be an efficient means to switch the magnetization of a thin film.

Fouling mechanisms of a light conventional crude were investigated by characterizing the crude oil, performing fouling tests using a bench-scale Alcor hot liquid process simulator (HLPS) unit and characterizing fouling deposits by means of elemental analysis, scanned electron microscopy (SEM), thermogravimetric analysis (TGA), and photoacoustic infrared spectroscopy (PAS-IR). In addition, a mathematical fouling model was developed under a laminar flow regime following Epstein's methodology. Fouling tests were conducted at different temperatures and bulk velocities. Although the asphaltene content in the crude oil is low, the asphaltenes are still unstable because of a high saturate content and this crude oil has a high fouling propensity. On the basis of the fouling test results, fouling model analysis, and characterization of fouling deposits, the fouling mechanism of this crude oil can be explained as follows: In a laminar flow regime, unstable asphaltenes transport to the hot surface, become attached to the surface, and then, through chemical reactions, form fouling deposits. Mass transfer of entrained suspended particulates in the crude oil also contributes to fouling, although it is not the main cause. However, under turbulent flow conditions, such as those that prevail in industrial operations, it is expected that suspended particles would play a greater role in fouling.

We report a theoretical model and experimental results for laser-induced local heating in liquids, and propose a method to detect and quantify the contributions of photochemical and Soret effects in several different situations. The time-dependent thermal and mass diffusion equations in the presence and absence of laser excitation are solved. The two effects can produce similar transients for the laser-on refractive index gradient, but very different laser-off behavior. The Soret effect, also called thermal diffusion, and photochemical reaction contributions in photochemically reacting aqueous Cr(VI)-diphenylcarbazide, Eosin Y, and Eosin Y-doped micellar solutions, are decoupled in this work. The extensive use of lasers in various optical techniques suggests that the results may have significance extending from physical-chemical to biological applications.

The Probe of Inflation and Cosmic Origins (PICO) is a NASA-funded study of a Probe-class mission concept. The toplevel science objectives are to probe the physics of the Big Bang by measuring or constraining the energy scale of inflation, probe fundamental physics by measuring the number of light particles in the Universe and the sum of neutrino masses, to measure the reionization history of the Universe, and to understand the mechanisms driving the cosmic star formation history, and the physics of the galactic magnetic field. PICO would have multiple frequency bands between 21 and 799 GHz, and would survey the entire sky, producing maps of the polarization of the cosmic microwave background radiation, of galactic dust, of synchrotron radiation, and of various populations of point sources. Several instrument configurations, optical systems, cooling architectures, and detector and readout technologies have been and continue to be considered in the development of the mission concept. We will present a snapshot of the baseline mission concept currently under development.

Naturally occurring amphotropic liquid-crystals were recently identified in unreacted hydrocarbon resources and resource fractions from around the world, including Athabasca bitumen. Liquid crystal forming constituents are present in both asphaltene and maltene fractions and appear to be an important class of materials that is missed entirely during conventional hydrocarbon characterization, i.e.: SIMDIST or SARA analysis. In this contribution, some physical properties of liquid crystals in Athabasca asphaltenes and maltenes identified using experimental methods as diverse as polarized light microscopy, differential scanning calorimetry (DSC), and mid-and near-infrared photoacoustic spectroscopy with depth profiling are reported. Liquid crystals, comprising materials with an aromaticity between that of maltenes and asphaltenes, form irreversibly on the surface of both asphaltene particles and maltene drops on heating. At higher temperatures the liquid crystals become isotropic but remain on particle surfaces. Liquid crystals do not reappear on cooling or subsequent reheating unless the samples are frozen and crushed between heating cycles. The interdependence of these phase properties on sample thermal and mechanical history may help explain unexpected and frequently deleterious surface and interfacial phenomena arising during Athabasca bitumen production and processing. ■ INTRODUCTIONLiquid-crystals were recently observed in unreacted petroleum fractions including Athabasca, Maya, and Cold Lake pentane asphaltenes, Safaniya heptane asphaltenes and a fraction of Athabasca bitumen were extracted with supercritical n-pentane (SFE6). 1 The liquid crystals form between 338 and 341 K for the pentane asphaltenes, 370 K for Safaniya heptane asphaltenes, and 316 K for SFE6. The liquid crystals disappear between 423 and 435 K for the pentane asphaltenes, 433 K for C7 Safaniya asphaltenes, and 373 K for SFE6. These materials also exhibit liquid crystalline domains in the presence of toluene vapor at room temperature. 1 Compounds that exhibit liquid crystalline properties in a defined temperature range between the melting point and the transition to the isotropic liquid state are called thermotropic. Compounds that show liquid crystalline properties by the addition of solvents are called lyotropic. For this type of liquid crystal, concentration constitutes an additional degree of freedom. Compounds that exhibit both types of behavior are termed amphotropic or amphitropic. 2 The liquid crystals observed in unreacted petroleum fractions belong to this latter group.Following these initial observations, detailed studies related to the thermophysical properties, physical structure, and chemical composition of the liquid crystals were initiated. For example, liquid crystal rich material extracted from Athabasca pentane asphaltenes comprises more than 10,000 different constituents. Their mean molecular size is smaller than asphaltenes, and they are enriched in heteroatoms relative to asphaltenes. Detailed chemical composition data...

We report on the first use of laser ablation to make submillimeter, broadband, antireflection coatings (ARCs) based on subwavelength structures (SWSs) on alumina and sapphire. We used a 515 nm laser to produce pyramid-shaped structures with a pitch of about 320 μm and a total height of near 800 μm. Transmission measurements between 70 and 140 GHz are in agreement with simulations using electromagnetic propagation software. The simulations indicate that SWS-ARCs with the fabricated shape should have a fractional bandwidth response of Δν/ν_center=0.55 centered on 235 GHz for which reflections are below 3%. Extension of the bandwidth to both lower and higher frequencies, between a few tens of gigahertz and a few terahertz, should be straightforward with appropriate adjustment of laser ablation parameters.

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