Hertzian Stress Cracks in Beryllia and Glass

The effect of Hertzian stresses resulting from loads acting at the points of contact of beryllia spheres was determined. As-drawn glass and glass ground with various grades of silicon carbide were indented with beryllia spheres, 1 in. in diameter. Also, pairs of these beryllia spheres were pressed together. Circular cracks due to Hertzian stresses were produced; an optical technique was developed for detecting them in a beryllia surface. The outer crack radius was proportional to the cube root of the maximum applied load. Average values obtained for the respective inner crack radii were used to determine average values of the minimum load to fracture these materials. The average minimum load to fracture 1 in. diameter beryllia spheres in air at room temperature under dynamic loading was 235 1b. The crack radius in glass and beryllia was about 20% greater than the radius of the contact surface. This was not significantly affected (in glass) by flaw density. It is considered that the Hertz analysis does not give the correct location and value of the maximum tensile stress when finite displacements of material occur.     

中国商用车领域的铂族金属需求依然强劲

2020年以来中国商用车市场发生了很多变化,近期卡车销量从疫情萧条中大幅反弹,物流、基建以及排放标准升级共同推动了2020年商用车市场需求,对铂族金属的需求更加有利,对铂金需求的预期增长似乎比对钯金需求更有保障。     

FOLLOWING THE MONEY: THE INFLUENCE OF CAMPAIGN FINANCE REFORM IN THE 2011 CHICAGO MAYORAL ELECTION

In this research we study the effect of recently enacted campaign contribution limits in Illinois via an examination of the 2011 Chicago mayoral election. Because contribution limits for state and local campaigns were implemented in the middle of the race for mayor we are uniquely positioned to test the efficacy of the new law. In theory we expect contribution limits to cause candidates to rely on more contributors making smaller donations. Our results indicate that the reform measure did not prompt candidates to broaden their fundraising base, and only when Rahm Emanuel's campaign is considered alongside his opponents’ did the fundraising law reduce average contributions. In a concluding section we address the issue of whether the contribution limits established under the law are too high to produce meaningful reform.     

High resolution observations of Weddell Sea surface currents using ERS-l SAR sea-ice motion vectors

Two areas of the Weddell Sea, one in the south and one in the west, were chosen for a preliminary investigation of sea-ice motion tracking from ERSt Synthetic Aperture Radar (SAR) images during the Austral summer. Only a small number of images were processed, so a manual tracking method was used. In the 3–day period between SAR images the atmosphere warmed near the surface, which led to significant changes in radar backscatter from, and thus in contrast between, ice floes and the areas between them. It was therefore not always possible to track features from one image to the next. The tracked features were clearly identified in images which were sub-sampled at onesixteenth of the full resolution available. In the southern Weddell Sea images, many large floes were present which allowed a quite detailed pattern of the surface water circulation to be mapped as the ice motion was predominantly forced by the ocean currents during a period of low surface wind speeds. The observed circulation pattern agreed well with previous observations from hydrographic surveys in this area north of the Filchner Ice Shelf. In the western Weddell Sea images good tracers were hard to find, but it was still possible to detect the edge of the western boundary current of the Weddell Gyre. Continuous monitoring of sea-ice motion in these two areas using SAR imagery could be a useful means of detecting changes in surface water flow which may be linked to the rate of formation of Antarctic bottom water.     

Binding of Meat Pieces: Influence of Some Processing Factors on Binding Strength and Cooking Losses

Evacuation of the chamber of the press used to form flaked beef into a restructured meat product (patty) did not affect the binding strength of the cooked patty but under some conditions decreased the cooking loss. In studies using patty mixes containing 0–1.0% added sodium chloride, meat binding strength increased with decrease in the temperature of the mix when formed into patties over the temperature range - 1° to -5°C. The largest effect generally occurred between - 1° and -2°C. However, the effect was only noted in patties that were frozen (-30°C) before being cooked for assessment. With decrease below - 1°C of the temperature of patties when pressed, cooking losses increased for the patties without added salt but decreased for those with added salt (0.5% or 1%). Change in the pressure applied to form the patty (in the range 1.4–13.7 MPa) can affect binding strength.     

Headspace Volatiles and Sensory Characteristics of Ground Beef from Forage- and Grain-Fed Heifers

Twenty-seven yearling Hereford-Angus heifers were allotted to one of three intense managed pasture systems: Tifleaf pearl millet, sorghum sudangrass and fescue-clover. After grazing, heifers were finished in drylot and then serially slaughtered at 0, 52, and 82 days in the feedlot (DIF). A total of 51 volatiles were identified in ground beef from Longissimus dorsi (L. dorsi) muscle and subcutaneous fat. Major classes of volatile compounds identified included hydrocarbons and aldehydes plus fewer numbers of ketones, alcohols, aromatic compounds and sulfur-containing compounds. The majority of compounds which varied due to DIF were alkanals and alk-2-enals. The concentration of each of the volatiles which varied due to DIF was found to increase. None of the volatiles quantitated were positively correlated with sweetness or gamey aftertaste, the two characteristics which were highest for the O DIF cattle.     

THE USE OF BORIC OXIDE IN GLASS-MAKING

Boric oxide behaves differently from other glass-making constituents in that the variation of physical properties is not progressively continuous with a variation in composition. With increase of boric oxide content in sodium borosilicate glasses, the refractive index (μ_D) rises to a maximum as also does the annealing temperature, while the coefficient of thermal expansion reaches a minimum and then rises. The durability, or resistance to water and hydrochloric acid reaches a maximum when the glass contains about 12% of boric oxide and subsequently falls off very rapidly. There is, accordingly, a limit to the usefulness of boric oxide in glass.     

Iterative,constrained 3-D image reconstruction of transmitted light bright-field micrographs based on maximum likelihood estimation

We present several image reconstruction algorithms for generating three-dimensional (3-D) renderings of bright-field micrographs that are founded on maximum likelihood estimation (MLE) theory. The basic principle of the algorithms is in estimating the values of the optical densities of the specimen. A computer simulation and initial experimental testing of a steepest ascent version of the algorithm is presented. The computer simulation demonstrates that the MLE algorithm has an advantage over previously used inverse filtering techniques in that it partially restores the zeroed Fourier components in the well-known missing-cone region. We present 3-D reconstructions from real biological data to show the potential of the algorithm in practical applications.