Willard F. Libby

Replacement Rates for Human Tissue from Atmospheric Radiocarbon

Carbon-14, derived from the testing of thermonuclear weapons in the atmosphere of the Northern Hemisphere during 1961-62, has been found in human tissues including the brain in amounts which reflect the atmospheric concentration of carbon-14 as of several months earlier. In collagen of cartilage, the rate of uptake of carbon-14 is much slower than in other tissues; essentially no radioactive carbon was found in the collagen of 70-year-old adults that had been exposed to the comparatively high concentrations of carbon-14 in the atmosphere during the years 1954 to 1964. Individuals from the Southern Hemisphere show little increase in the carbon-14 content of their tissues at present, and detailed tests with individuals traveling to the Northern Hemisphere from the Southern allow closer scrutiny of the tissue replacement rates.

Radiocarbon Content of Marine Shells from the California and Mexican West Coast

The radiocarbon content of contemporary pre-bomb marine shells from the upwelling environment of the California and the West Mexican coast has been determined. In addition, factors leading to the apparent ages of different magnitude for various marine environments are discussed.

UCLA Radiocarbon Dates V

Radiocarbon measurements carried out during 1965 are reported on archeologic-historic samples from California, Nevada, Mexico, Peru, Brazil, Philippines, Spain, England, Egypt, and Africa. Geophysical, geological-climatological and biological measurements are given for: C-14 in atmospheric carbon dioxide (California), bomb C-14 in foodstuffs (California, Australia, Colombia), bomb C-14 in human tissues (widespread localities), bomb C-14 in plants (Colorado), oceanic measurements (California, Mexico), vegetation and climate (California, Texas, Nevada), and geological processes (California, Israel).

Radiocarbon Dating of Bone and Shell from Their Organic Components

A method of dating bone and shell by radiocarbon content has been developed. The mineral is removed by mild acid treatment and the residual carbon is dated in the usual manner.

Sintered diamond compacts with a cobalt binder.

Diamond powder can be successfully cemented with cobalt. At 62 kilobars the sintering occurs over the temperature range from 1570� to 1610�C. The maximum microhardness of the compact (〉 3000 kilograms per square millimeter on the Knoop scale) is obtained with a mixture of 20 percent cobalt (by volume) and a diamond particle size of 1 to 5 micrometers.

Equilibration of Atmospheric Carbon Dioxide with Sea Water: Possible Enzymatic Control of the Rate

Surface and subsurface ocean water differ in exchange characteristics with atmospheric carbon dioxide. The possibility of control by an enzyme like carbonic anhydrase has been experimentally explored.

UCLA radiocarbon dates IV.

Reports of carbon-14 dating are grouped under archeologic-historical dates and under geophysical, geologic, and biologic measurements. Samples studied in the first group came from the United States, Mexico, South America, the Pacific, Europe, Asia, and Africa. The second group included studies of carbon-14 in the atmosphere in California and Galapagos Islands, bomb radiocarbon in human tissues; plants and seaweed from California; seawater off Baja California, Mexico; tree rings from Arizona and California; vegetation and climate, southwestern United States; geologic processes as shown in samples from California and Wisconsin.

Primaeval melting of the Moon

There is evidence that the Moon melted completely 4,400 Myr ago, and between 4,000 Myr and 3,200 Myr ago had an internal magnetic field. But gravity could not have provided the heat of melting, and it must have come from short lived radio elements. Theory suggests the transuranics with atomic numbers between 114 and 126 may be relatively stable, and it is shown that these ‘superheavy elements’ fit the requirements of the early heat source in the moon.

The possibility of superheavy elements in iron meteorites

The possible role of superheavy elements in the early Moon is reviewed. The siderophilic superheavy elements (possibly Z = 114, 115, 116) may have been the heat source in the Moons iron core needed to generate the ancient lunar magnetic field. It is suggested that in the search for present day evidence of the existence of these hypothetical elements, iron meteorites may be a key. The available data on their trace elements are reviewed and future work to determine whether they are in part fission products from metallic superheavy elements is suggested.

Radio Reflection by Free Radicals in Earth's Atmosphere.

Reflections of megacycle-per-second radio signals by free radicals in Earths ionosphere are observed having about the intensity predicted for induced magnetic-dipole transitions. It seems that magnetic atoms, ions, and molecules in planetary atmospheres may be detected by this method. These cbservations were made with the topside ionosonder of the Canadian satellite Alouette II.