ISSN:0034-6748    

DOI:10.1063/1.1769998

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

A heterodyne beat apparatus operating on alternating current is described. The essential features are: (1) a crystal controlled oscillator, (2) a variable capacitance oscillator, and (3) the power supply. By properly choosing plate potentials and by using a line voltage stabilizer the effects of normal voltage variations have been essentially eliminated. The frequency stability is found to be quite good, and the time of warm‐up rather short. Especial care was given to rigidity of mountings, and to thermostating of both oscillators. Circuit details are shown in figures.

ISSN:0034-6748    

DOI:10.1063/1.1769999

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

The cosmic‐ray radio sonde described in this paper was used for observations in the stratosphere near the magnetic equator. The instrument can be used for single counters or coincidences up to fourfold. It includes the necessary amplifiers and scaling circuits to operate a relay which keys the radio‐transmitter. High voltage for the counters is provided by a buzzer and transformer unit. Small storage batteries are used for power to operate the unit for about three hours. Pressure and temperature signals are sent at eight‐minute intervals. The complete instrument ready for flight, weighs about 3300 grams. The receiving equipment consists of a super‐regenerative receiver with the signal output recorded on a paper tape.

ISSN:0034-6748    

DOI:10.1063/1.1770000

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

The detection of quantities of radon of the order of 10−12curie by means of a proportional counter is discussed. Two methods are investigated. In one the radon is concentrated in a liquid‐air trap before it is put into the counter and in the other the volume of the counter is made sufficiently large so that the radon can be swept into the counter with a few liters of inert gas. The first method has the advantage of requiring only small counters which work at conveniently low voltages but has low efficiency. The second method has the advantage of simplified filling technique and higher efficiencies, but suffers from the difficulty of obtaining stable operation unless the sweeping and filling gas is helium.

ISSN:0034-6748    

DOI:10.1063/1.1770001

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

A circuit is described for recording the low intensity flashes of light of luminous animals, with examples of its application to the firefly flash. Between an alternating current source and a high gain a.c. amplifier, a photo‐cell bridge circuit is introduced which is capable of blocking the a.c. signal when the photo‐cells are dark. Light falling on the photo‐cells allows the a.c. signal to pass the bridge, the output of the bridge being amplified and recorded photographically by the use of the cathode‐ray oscilloscope.

ISSN:0034-6748    

DOI:10.1063/1.1770002

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

An analytical cell has been designed for the angle type quantity rotor of the air‐driven ultracentrifuge. Sieve‐like partitions covered with filter paper separate the cell into two or three compartments from which fractions can be removed for chemical analysis or for bioassay. Fourteen tubes each containing 4.5 cc of solution can be run simultaneously. Equations have been derived for the calculation of sedimentation constants from the analytical data.

ISSN:0034-6748    

DOI:10.1063/1.1770003

出版商:AIP    

年代:1942

数据来源: AIP

摘要:

A differential photoelectric colorimeter has been built for the high speed measurement of small absorption changes in enzyme substrate reactions. Under the conditions of the experiments, the total differential change of light intensity was approximately 0.2 percent and a photoelectric resolution of approximately 1.7×104was achieved, giving an accuracy of 3 percent. The time resolution of the system was at least 0.01 second and a complete kinetic curve was obtained with as little as 0.5 cc of peroxidase solution of 1×10−6molar hematin iron.

ISSN:0034-6748    

DOI:10.1063/1.1770004

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770006

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770007

出版商:AIP    

年代:1942

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770008

出版商:AIP    

年代:1942

数据来源: AIP