摘要:

A simple NMR system was used for measurement of the o&sngbnd;H2concentration in the solid phase. It was found that the system must be calibrated, as the integral of the NMR absorption curve is not proportional to the o&sngbnd;H2concentration, which was suggested earlier. The influence of the quantum diffusion below 4 K and 0.35 o&sngbnd;H2content on the results is reported.

ISSN:0034-6748    

DOI:10.1063/1.1686521

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

This paper describes the development of a radioactive tracer system using an electro‐optical image intensifier integrated with a low light level photographic system to permit recording of concentration profiles in liquid systems undergoing diffusion. Diffusivities of liquid components can be rapidly and accurately determined from the resultant concentration‐position‐time data. Results for thed‐glucose‐water system at 25°C are presented.

ISSN:0034-6748    

DOI:10.1063/1.1686522

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The general problem of designing active proportional thermostats is discussed, and a design philosophy is deduced. The application of this philosophy to the construction and operation of a precision proportional thermostat for geophysical accelerometers in boreholes is described in detail. The thermostat discussed is of small size and weight, is simple to operate, and requires less than 5 W of power. It maintains the temperature of an instrument and its vacuum enclosure of 1688 cm3total volume and 7 kg mass constant within 10 &mgr;°C over periods of days in the presence of fluctuations in the ambient temperature of several degrees. Various models of the thermostat, with several different configurations of thermal insulation, have been tested extensively in both laboratory and borehole environments. Stable proportional operation has been achieved with setpoint temperatures ranging from 15 to 35 °C and with the difference between the setpoint and mean ambient temperatures varying from 4 to 10 °C. The electronic circuitry is designed to provide a maximum heater power of 15 W, and the thermistor is calibrated over the range −40–150°C. With suggested modifications, the thermostat is applicable to a variety of instruments over a fairly wide temperature range.

ISSN:0034-6748    

DOI:10.1063/1.1686523

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A stripline resonator for ESR is described. Spectra obtained show that the relatively lowQvalue, as compared with a standard cavity, is to a high degree compensated by the higher filling factor. The same resonator can be used for different frequencies. At low ESR frequencies the size of the resonator is much smaller than that of a cavity. A possibility of obtaining circularly polarized radiation is pointed out.

ISSN:0034-6748    

DOI:10.1063/1.1686524

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A special camera has been installed on a research sailplane to takein situphotographs of atmospheric particles. Ice particle shapes, sizes, and concentrations; raindrop sizes and concentrations; and estimates of cloud droplet concentrations and maximum sizes are obtained from the photographs. The camera is capable of photographing particles as small as about 4 &mgr; radius; the size of the largest particle completely imaged is limited by the 24×36 mm projected area photographed. Liquid particles can be distinguished from ice particles for radii greater than 50 &mgr;. Techniques are described for calibrating the camera so that both in‐focus and out‐of‐focus images are used for obtaining concentration and size data. Examples of photographs of ice particles, raindrops, and cloud droplets are shown. Camera improvements for getting more data for a given length of flight are suggested.

ISSN:0034-6748    

DOI:10.1063/1.1686525

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We have investigated the interbase resistances of 12 General Electric 2N2646 unijunction transistors between 20 and 300 K. Although the resistance is not a single‐valued function of temperature, the heavily n‐doped silicon chip is an inexpensive thermometer of high sensitivity that is free of thermal cycling or current dependent effects. Its small thermal mass makes it well suited for measurements such as specific heat.

ISSN:0034-6748    

DOI:10.1063/1.1686526

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A computer interface for a clinical chemistry analyzer has been implemented using an MOS microprocessor. The interface uses ANSCII serial data transmission, incorporates error detection and correction, and may additionally serve as a teleprinter driver. Several benefits resulted from the use of a microprogrammable processor. Design changes during the development cycle were easily accommodated, and different instruments or communications protocols may be accommodated by changing only the microprogram stored in an erasable, reprogrammable read‐only memory.

ISSN:0034-6748    

DOI:10.1063/1.1686527

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Mating Teflon rings hermetically seal a disk‐shaped sample between the plates of a three‐electrode system to hold moisture content constant at various temperatures. The sealing joint of the Teflon rings is flexible enough to ensure contact between the electrodes and the sample in spite of variations in the sample thickness.

ISSN:0034-6748    

DOI:10.1063/1.1686528

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Use of a magnet to clamp a magnetic metal mask to the substrate during sputtering resulted in good edge definition in thin film patterns.

ISSN:0034-6748    

DOI:10.1063/1.1686529

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An all‐metal feedthrough which permits superconducting leads to pass from the4He bath into the vacuum region of a cryostat is described. The all‐metal construction facilitates rapid assembly and enables the seal to withstand rapid temperature changes resulting from the precooling of the apparatus with liquid nitrogen. Use of the device is limited to those applications, such as operation of superconducting magnets, in which the presence of normal connections between the various leads or to the metallic structure of the cryostat can be tolerated.

ISSN:0034-6748    

DOI:10.1063/1.1686530

出版商:AIP    

年代:1974

数据来源: AIP