The Au-In-Pb system:The AuIn2-In-Pb portion

The Au-In-Pb system was investigated in the AuIn-In-Pb portion of the system. Pb-AuIn and Pb-AuIn₂ quasibinary systems were found:the first, consisting of a eutectic and a monotectic reaction and the second, a eutectic with an inflection in the liquidus. The chief source of information was differential thermal analyses and verification by metallography, X-ray diffraction and microprobe analyses. Four isothermal reactions were found as follows: 1) L₁ ⇌ L₂ + AuIn₂ + AuIn at 433°Celsius 2) L₁ ⇌ Pb + AuIn₂ + AuIn at 316°Celsius 3) Pb + L ⇌ α + AuIn₂ at 172°Celsius 4) α₁ + L ⇌ AuIn₂ + In at 159°Celsius. Verification of these events and the isopleth from 50-50 wt pct Pb-In, a typical solder, to ≈ 47 wt pct Au are given. This work was supported by the United States Energy Research and Development Administration.     

MOZAMBIQUE-MADAGASCAR GEOSYNCLINE, I: DEPOSITION AND ARCHITECTURE

The Mozambique-Madagascar geosyncline consists of an open-ended non-compressional NNE-SSW downwarp 1,700 km long in the area of the present Mozambique Channel and its bordering coastal regions. Exposed basement marks the lateral boundaries of the geosyncline, and embayments rather than discrete basins modify its regional geometry. A sedimentary volume of more than 5,000,000 cu km resulted from subsidence and hypersubsidence, not only in the Mozambique Channel but also on the coastal borders, in places relatively close to exposed basement. Continental facies of South African Karroo type dominates the sedimentary columns of the geosynclinal flanks in the Upper Carboniferous to Middle Jurassic interval, but is not yet documented beneath the bathyal and abyssal waters of the intervening Mozambique Channel. Marine facies, mixed facies, and a few continental facies occupy the sedimentary columns of the flanks above the Middle Jurassic. Pelagic facies may be dominant in contemporaneous strata now below the bottom of the Channel. As part of the vast non-compressional province of the Indian Ocean the Mozambique-Madagascar geosyncline has been subjected only to epeirogeny. The structural response has been normal faulting, in some places, with major downthrow and in others antithetic with patterns of graben and horst. Volcanism is known to have accompanied the faulting from Late Triassic time onward. Modern consensus invokes a separation of Madagascar from Africa followed by drift along southward, eastward, or NE paths, depending upon individual tectonophysical interpretation, each of the three of which displays weakness. The alternative of separation by subsidence only needs the test of deep drilling under the present Mozambique Channel for support orproof Until then, a tentative scheme of stratal succession is proposed, namely, a relatively-thin post-Karroo column in pelagic facies and a relatively-thick Karroo column in continental and mixed facies. Confirmation of the succession by drilling would provide strong support of a model presenting paleo-Madagascar as the eastern sector of an Africa that bulged more than once toward the east in post-Carboniferous time. The corollary of a broad band of reservoir Karroo, under a broad cover of pelagic post-Karroo, all under the waters of the present Mozambique Channel would be of considerable interest to explorationists.     

Fifty years of polymer research

The writer summarises his researches in the field of polymer science. He began with studies of the structures of space-network and sheet polymers in crystals. Currently he is working on the structures of macro-ions in silicate and borate crystals and glasses and on the development of a new theory of structures and thermodynamic properties of (polymer and other) solutions.     

Teaching Morse-Code reception with signals weighted in frequency according to their difficulty.

An experimental group (N = 19) was trained to receive Morse code with signals that were weighted with respect to frequency of presentation in rough proportion to their order of difficulty for beginners. A control group (N = 19), matched on a code aptitude test performance, was trained with each signal presented an equal number of times. On the test runs, no significant differences were observed in the progress of the two groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Localized measurement of optical attenuation coefficients of atherosclerotic plaque constituents by quantitative optical coherence tomography

Optical coherence tomography (OCT) is a novel, high-resolution diagnostic tool that is capable of imaging the arterial wall and plaques. The differentiation between different types of atherosclerotic plaque is based on qualitative differences in gray levels and structural appearance. We hypothesize that a quantitative data analysis of the OCT signal allows measurement of light attenuation by the local tissue components, which can facilitate quantitative spatial discrimination between plaque constituents. High-resolution OCT images (at 800 nm) of human atherosclerotic arterial segments obtained at autopsy were histologically validated. Using a new, simple analysis algorithm, which incorporates the confocal properties of the OCT system, the light attenuation coefficients for these constituents were determined: for diffuse intimal thickening (5.5 +/- 1.2 mm(-1)) and lipid-rich regions (3.2 +/- 1.1 mm(-1)), the attenuation differed significantly from media (9.9 +/- 1.8 mm(-1)), calcifications (11.1 +/- 4.9 mm(-1) ) and thrombi (11.2 +/- 2.3 mm(-1)) (p < 0.01). These proof of principle studies show that simple quantitative analysis of the OCT signals allows spatial determination of the intrinsic optical attenuation coefficient of atherosclerotic tissue components within regions of interest. Combining morphological imaging by OCT with the observed differences in optical attenuation coefficients of the various regions may enhance discrimination between various plaque types.     

Desorption/ionization fluence thresholds and improved mass spectral consistency measured using a flattop laser profile in the bioaerosol mass spectrometry of single Bacillus endospores

Bioaerosol mass spectrometry is being developed to analyze and identify biological aerosols in real time. Mass spectra of individual Bacillus endospores were measured with a bipolar aerosol time-of-flight mass spectrometer in which molecular desorption and ionization were produced using a single laser pulse from a Q-switched, frequency-quadrupled Nd:YAG laser that was modified to have an approximately flattop profile. The flattened laser profile allowed the minimum fluence required to desorb and ionize significant numbers of ions from single aerosol particles to be determined. For Bacillus spores, this threshold had a mean value of approximately 1 nJ/microm(2) (0.1 J/cm(2)). Thresholds for individual spores, however, could apparently deviate by 20% or more from the mean. Threshold distributions for clumps of MS2 bacteriophage and bovine serum albumin were subsequently determined. Finally, the flattened profile was observed to increase the reproducibility of single-spore mass spectra. This is consistent with the general conclusions of our earlier paper on the fluence dependence of single-spore mass spectra and is particularly significant because it is expected to enable more robust differentiation and identification of single bioaerosol particles.     

Chebyshev and Taylor approximations of polarization mode dispersion for improved compensation bandwidth

We examine a series of experimentally realizable procedures for wide-bandwidth polarization mode dispersion compensation based on Taylor and Chebyshev approximations to the transfer matrix for light polarization in optical fibers. Our results demonstrate that a symmetric ordering of compensator elements in the Taylor procedure improves performance and that methods based on the Chebyshev approximation can significantly widen the compensation bandwidth.     

Influence of chitosan characteristics on the coagulation and the flocculation of bentonite suspensions

Ten chitosan preparations with different molecular weights (MW) and degrees of deacetylation (DD) were tested for coagulation of 5 g L(-1) bentonite suspensions at pH 5 and 7 in demineralized water (DW) and in tap water (TW). Coagulation was better in TW than in DW for every condition and lower doses of chitosan were required at pH 5 than at pH 7. More than 95% of residual turbidity (after sedimentation in the absence of chitosan) was removed using less than 0.10 mg L(-1) chitosan in either TW or DW at pH 5 or in TW at pH 7. Higher doses were required for removal of turbidity in DW at pH 7, but in all cases the effective concentrations of chitosan were much lower than required for complete neutralization of the negative charge on the bentonite particles. Removal of turbidity was best for the higher MW chitosans in either the B series (89.5% DD) or the C series (95% DD) of chitosans. Overall, the results were consistent with destabilization of bentonite by the combined mechanisms of electrostatic patch and bridging. The improved performance of chitosan in TW could have been due to improved attachment to bentonite due to the presence of sulfate and other counter-ions in TW.