Beryllium Powder Research Articles

The warm pressing of beryllium powder

Compacting below the recrystallization temperature was studied. Ideal density was attained at 550° to 600°C using 25 tsi. Compacts have strength and hardness higher than cold worked beryllium. The recrystallization temperature of this highly stressed metal is that of cast, cold worked beryllium and appears independent of pressing temperature.

Preparation of Beryllium Powder

Transactive response DNA binding protein (TDP-43) is a biomarker associated with neurodegenerative diseases, specifically amyotrophic lateral sclerosis (ALS). ALS remains without treatment or a cure, and diagnosis relies on the onset of symptoms. Hence, novel methods are needed for the early detection of TDP-43 as an ALS biomarker. Toward this aim, the detection of full-length phosphorylated TDP-43 (pTDP-43) was achieved by using the electrochemical impedance spectroscopy (EIS)-based biosensor. The TDP-43 antibodies (Abs) on gold (Au) surfaces (Ab-Au) were employed as recognition probes for the protein detection. EIS was used to characterize the Ab-Au surface before and after pTDP-43 binding. In the presence of a solution redox probe, [Fe(CN)6]3-/4-, the dramatic changes in the charge-transfer resistance (Rct) values were observed after the pTDP-43 binding and were directly related to the amount of protein present in solution. Sensitivity for pTDP-43 was highly dependent on the antibody used as a recognition probe, and the limit of detection was 11 ± 6 nM with a large dynamic range, and an excellent selectivity against the common protein. The electrochemical immunosensor may be easily extended for the detection of other degenerative disease biomarkers.

-Ray Spectrum of Radio-Helium

IN order to investigate the energy distribution of the -rays from radio-helium1, we have employed an expansion chamber constructed by Dr. J. C. Jacobsen and kindly lent to us. In the middle of the top plate, a thin-walled brass cylinder (0.05 gm. per cm.2, 1.5 cm. diameter) was inserted, into which an activated beryllium cylinder could be dipped. The latter was made of beryllium powder (0.12 gm. per cm.2) stuck on to a brass tube (0.1 gm. per cm.2) and could be moved automatically from a position around a neutron source (beryllium-radon) to the position in the Wilson chamber in 0.4 sec., this movement also starting the timing arrangement for expansion and light. A suitable lead shielding was arranged which cut down the electrons due to the -rays to a number small compared with the number of -rays. The radioactivity induced in the brass tube carrying the beryllium is negligible as the latter is exposed to the neutrons only for a few seconds at most every minute.

Loss of Velocity of Neutrons in Heavy Water

WE have made some experiments on the Fermi effect produced in silver, when the neutrons are allowed to pass through a layer of heavy water. We used double-walled cylindrical glass vessels which could be filled with ordinary water or heavy water of 98 per cent purity. The neutron source, a tube containing radon mixed with beryllium powder, was placed in the narrow inner tube of this double-walled vessel.

Radiopotassium and other Artificial Radio-elements

IN a letter published in NATURE of January 19, it was shown that the bombardment of scandium with neutrons leads, beside the formation of an active scandium isotope1 20Sc46, to the formation of a new potassium isotope 19K42 having a half-life value of about 16 hours and emitting (-rays the intensity of which is reduced to one half of its initial value by an aluminium foil of approximately 0.7 mm. thickness. We were recently successful in preparing this potassium isotope K42 by the bombardment of calcium by neutrons according to the equation: Calcium carbonate, after being exposed to neutrons produced by a mixture of 200–300 mgm. radium emanation and beryllium powder, was dissolved in dilute hydrochloric acid, 150 mgm. sodium chloride added and the calcium precipitated as oxalate. The filtrate was found to be active and the measurement of both the rate of decay and the absorption of the radiation emitted has shown the presence of 19K42. The yield of K42 from calcium is a low one, which is due chiefly to the fact that the isotope Ca42 is only present to the extent of 0.8 per cent in the mixed element calcium. It is now possible to produce the potassium isotope K42 by each of the following reactions: When applying neutrons slowed down by Fermi's device by reflection by hydrogen nuclei, an active calcium isotope was obtained which decays with a period of 4 hours, the formation of which is due to one of the following two reactions: the latter being the more probable one.

Disintegration of Light Atomic Nuclei by the Capture of Fast Neutrons

ABOUT thirteen disintegrations of neon nuclei have been obtained in 3,200 pairs, and approximately 100 disintegrations of nitrogen nuclei in 7,600 pairs of photographs of a Wilson chamber through which neutrons were passing. The source of the neutrons consisted of beryllium powder intimately ground with a mixture of mesothorium and thorium-X. The neutron source used was on the average more powerful in the experiments with neon than with nitrogen. If all the factors are taken into account, it is found that with identical atomic concentrations of neon and of nitrogen in the chamber, the neon nuclei are disintegrated much less often than those of nitrogen.