An LCAO-MO calculation of the energies of the states of bianthrone with the anthracene ring systems respectively coplanar and perpendicular indicates that the latter state should be more energetic than the former state by about 3.3 kcal. This compares quite favorably with the experimental data of Grubb et al. which show that the thermally excited state of bianthrone observed in the phenomenon of thermochromism is more energetic than the ground state by 3.5 kcal.

Since its discovery in 1928 monoamine oxidase has stubbornly resisted various attempts at purification. An explanation for this behavior emerged from the demonstration of the enzyme's intimate adherence to the cytoplasmic particulate elements. Various efforts were subsequently made to release this system into solution by means of disruption of these bodies. The result was either loss of activity or the production of smaller microscopic particles to which in turn the enzyme was attached. Such experiences strengthened the earlier opinion that "monoamine dehydrogenase" was a complex of several enzymes acting in unison or in sequence, in a fashion parallel to that postulated in the case of succinic dehydrogenase.

The experiments to be described are concerned with a comparative study of the mutagenic effectiveness of thermal neutrons in producing sex-linked lethal mutations in male and female Drosophila melanogaster. Some of this work has appeared previously in abstract form. Preliminary comparative studies of the mutagenic effectiveness of X-rays in producing sex-linked lethal mutations in male and female Drosophila have already been described. The most extensive study to date on cytogenetic changes accompanying thermal neutron treatment is that of Conger and Giles working with Tradescantia.

A series of measurements was performed to investigate the gamma ray spectra, in the region from about 100 kev to about 3 Mev, resulting from the capture of thermal neutrons in a number of elements. The purpose of the experiment was to supplement the high energy capture gamma ray data in order to remove some of the ambiguities from the proposed energy level schemes and to obtain information for the Shielding Group of Brookhaven National Laboratory on elements normally found in reactors.

Selective incorporation of radioactivity from proteins of labeled chorio-allantoic grafts of adult chicken tissues into proteins of homologous tissues of host chick embryos.

A study has been made of xenon concentration changes in brain and other body tissues of the dog during inhalation of radioactive xenon. The xenon concentrations of the thalamus, hypothalamus, caudate nucleus and medulla oblongata were similar and significantly higher than those of the cerebral parietal cortex at the two and six minute periods of inhalation. Whereas four of the five brain tissues studied were saturated within about six minutes, the cerebral parietal cortex may not be completely saturated even after a twenty minute period of inhalation of xenon at a constant tension. The xenon concentration of adrenal gland tissue rises rapidly and exceeds that of the brain tissues after about a ten minute period of inhalation. Kidney, liver and striated muscle absorb xenon more slowly than the other tissues studied.

We have made absolute radiochemical measurements of the yields of Kr-85 and Xe-133 in the thermal neutron fission of U-235, and of Kr-85 in the thermal neutron fission of Pu-239. For Kr-85 in U-235 fission, the mean of eight measurements gives the ratio, X/T, of fission yield to half-life: X/T = 0.0253%/yr; σ = 1.59%; 99-1 error of the mean = 2.41%. For Kr-85 in Pu-239 fission, the mean of three measurements gives X/T = 0.0092%/yr; σ = 4.3%. Here σ is the standard deviation of a single measurement expressed as percent of the mean. If the Kr-85 half-life is 10.8 (±4%) yr, the yields are U-235 fission: X = 0.273% (±5% of X). Pu- 239 fission: X = .0994%. The error estimate in the U-235 yield is an accuracy estimate compounded of estimated accuracies of 3% in the X/T value and 4% in the half life. For Xe-133 in U-235 fission, the mean of five measurements gives the yield: X = 6.62%; σ = 0.095% of X; accuracy = ±3% of X. The accuracy estimates are based on a detailed investigation of the possible sources of error in the fission counting, the chemical procedure, and the beta-counting (gas-phase proportional …

A short review of the field of internal conversions. Isomeric transitions teach us many details of nuclear structure. In these studies electromagnetic theory is considered as a "tool". It is a quite quantitative tool in the case of "internal conversion" - a phenomenon which has been widely studied for many years. Internal conversion takes place in competition with γ-ray emission: a fraction of the nuclei in excited states decay by γ-ray emission, the remaining fraction by transferring the energy to K, or L, etc. electrons in the atomic shell. Thus the lifetime of an excited nuclear state depends on the internal conversion coefficient. As internal conversion must be expected to depend on the details of the electronic environment, the lifetime of an isomeric state depends on the state of chemical combination of the isomer - as was recently shown explicitly in one case, that of Te-99m(6hr.).

The comparative approach to the study of thyroid function, as illustrated by the studies of Gorbman, Gudernatsch and Payne on lower vertebrates, has been profitable. Another type of comparative approach has been made, chiefly by Baumann, by studying the ability of the thyroid to accumulate various members of the halogen group of elements. This work dates from the fundamental demonstration by Baumann that the thyroid is capable of concentrating iodine. The introduction of radioisotopes of iodine in the study of thyroid function by Hertz, Roberts and Evans and Hamilton, Soley and Eichorn has helped to advance these studies.

Groups of Habrobracon during postembryonic development were exposed to X-rays in the presence of oxygen, carbon dioxide, nitrogen and hydrogen. The effects on development to adulthood were observed. Pupae exposed to 100 per cent oxygen (without X-radiation) were arrested in their development. Diploid female pupae were more resistant to X-rays and more sensitive to oxygen than were comparable haploid male pupae. Groups of Habrobracon irradiated during the larva-in-cocoon stage in the presence of nitrogen or carbon dioxide were about three times as radioresistant as comparable groups X-rayed in air or oxygen. The amount of protection from X-radiation by nitrogen was the same for oxygen-sensitive and oxygen resistant stages. There does not appear to be a clear relationship between oxygen poisoning and X-radiation damage. Groups of Habrobracon during the larva-in-cocoon stage were more radioresistant when X-rayed in the presence of hydrogen than in the presence of nitrogen or carbon dioxide than when X-rayed in hydrogen. These experiments show that the radiosensitivity of Habrobracon can be modified by the presence of hydrogen.

The increasing use of prolonged Na restriction in the treatment of cardiovascular diseases in particular, makes study of long-term Na balance pertinent. With diets which contain 2 to 7 mEq. Na per day, combined urine and stool losses average 1 to 5 mEq. Na per day. Therefore, over an extended period the loss of electrolyte through the skin assumes importance. It is well known that marked sweating may be associated with considerable loss of NaCl through the skin. However, except for Benedict's classical study of an individual who fasted for one month, few data have been found on total minimal skin losses after Na restriction. In the first study Na was restricted for three days; in the second for fourteen days. Although Benedict's data have relevance to any work on the physiological effects of dietary restriction, it is obvious that total elimination of Na from a diet would be both dangerous and impractical.

A study was made of the movement of the phosphorus of yeast ingested by adult female Drosophila melanogaster. It was found that seventy to eighty percent of the phosphorus in yeast is extracted during its passage along the gut. An average of 90% of the extractable phosphorus of the meal has passed through the gut to other tissues by the time the digestive tract has emptied. Incorporation of medium P into eggs is very rapid. Eggs laid by week old females contain over thirty times as much exogenous phosphorus as endogenous phosphorus. It is demonstrated that a Drosophila melanogaster female may ingest daily an amount of yeast equal to two times its body weight. During the day an amount of phosphorus equal to the amount of phosphorus in the ingested yeast is lost. Twenty percent of the phosphorus lost is non-absorbed phosphorus of the meal. Fourteen percent of the phosphorus lost is in eggs. Sixty-six percent of the phosphorus lost is in forms other than eggs (probably in secretions of the salivary glands, digestive tract and malpighian tubes. The relation between endogenous phosphorus remaining and time follows a two phase system where the slow phase has a half time longer …

Irradiation with approximately 60,000r kills fasted adult Drosophila melanogaster within one day and is lethal to 60% of the non-fasted flies within two weeks. Males die sooner than females. However, males show little or no modification of phosphorus turnover and maintain their weights at control values. In contrast, the rate of growth of irradiated females is slowed down, but the flies eventually reach weights in excess of controls. Irradiated females have fast and slow phases of phosphorus turnover with lengthened half-times. The phase systems of fast and slow half time are affected to different degrees by irradiation. However, irradiation does not affect the amount of phosphorus lost by each phase or the total phosphorus content of either sex of flies. The biological half time for phosphorus is 0.9 days for normal females, 8.0 days for irradiated females and 1.8 days for normal or irradiated males. Irradiation does not have an immediate effect upon the efficiency of phosphorus extraction from yeast by the gut. It does have an immediate depressing effect upon food intake and a depressing effect six days after treatment upon the oxygen consumption of the flies.

The paucity of pre-meiotic mutations in maize has prompted a cytogenetic analysis of one which occurred at the R locus. Cytogenetic tests of a spontaneous pre-meiotic R --> r mutation indicate that it is an autonomous mutation for the R locus. No evidence was found for a factor, other than the R locus, as a causal agent for the mutation. The mutant behaves as a stable r allele. No evidence was found for chromosomal alteration, pollen or transmission sterility. Thus, within the limits of the tests made, it must be called a point mutation.

The high incidence of drought conditions in recent years has caused considerable concern among agriculturalists in eastern Long Island. A convenient method of computing soil moisture on a daily basis has therefore been sought in order to provide a quantitative estimate of present and past conditions.

Estimation of radioactive iron in tissues from animals given this material has commonly involved the following: The iron is separated from wet-ashed tissue as the sulfide or oxide, or from dry-ashed tissue as a complex with isopropyl ether or cupferron. The iron is converted to the oxalate or citrate and then electroplated on copper as preparation for estimation of radioactivity.

By heating the normally cool areas of graphite to temperatures of 200°C or higher, it is evident that a substantial portion of the energy stored will be released. The physical dimension change which is associated with the radiation damage of graphite has been noted to partially recover under laboratory conditions when this amount of stored energy is released. This latter phenomenon is of prime interest in this operation. If a dimension recovery is noted on the gross structure, a solution to certain formidable operating problems may have been achieved.

Safe startup and operation of the nuclear reactor requires neutron sensing instruments to cover a range of about 10^9. This coverage is obtained by a counting rate meter, a period meter, and a high level power indicator. At normal operating levels, the reactor is regulated by the high level power controller and protected by the high level trips. Emergency shutdown of the reactor can be initiated by any one of the 54 different conditions. Since these safety circuits are almost 100% "fail safe", careful design, good maintenance, and cautious operation have been necessary to avoid accidental shutdowns. The period trips and high level trips are provided in triplicate for safety and are coincidence-connected in pairs to guard against accidental shutdown. The use of suppressed-zero circuits has proved helpful. The theory of coincidence-connected trips is briefly discussed.

Previous analyses of the behavior of tracers in three-compartment systems are incomplete, are scattered throughout the literature and are expressed in a confusing variety of notations. This article purports to unify the previous contributions and further to develop the application of the mathematical basis involved in the interpretation of experimental data, with emphasis on the relationship between the behavior of tracers and the exchange rates of their carriers in steady-state systems.

A miniaturized goniometer for single-crystal neutron diffraction has been described previously. The present note describes a second single-crystal instrument, which consists of a modification of the commercially-available General Electric "SPG" X-Ray Spectrogoniometer. The specimen holder, incident slit system and Geiger counter mount is removed from the SPG instrument. A divided circle is mounted on the specimen holder table, and this circle is rotatable by means of a worn-gear. The worn and gear are cut so that one revolution of the worn corresponds to a 1° rotation of the divided circle. Divisions on the worn rotation knob are marked to 0.01°. The worn can be disengaged, for rapid rotation of the divided circle.

In order to perform the various experiments with a bubble chamber, a high intensity flash tube is used. This report briefly describes the power supplies designed and constructed to power these lamps.

One might expect that the Cosmotron would offer certain advantages over cosmic rays for the study of heavy unstable particles; provided, of course, that it can produce them. In the first place, the conditions under which they are produced could be controlled to a considerably greater extent. In the second place, it might be possible to arrange conditions under which they would be observed more abundantly, an actual beam of heavy mesons being the ideal situation.