摘要:

Presented here is a detailed description of a magnetic osmometer as well as the theory of its operation. This instrument has the pressure sensor and is placed on the dialysate side of a semipermeable membrane and is capable of measuring pressure changes as low as 1×10−3cm of water. The stability of the system is greatly enhanced by maintaining contact with a large thermally stable atmosphere. This eliminates ordinary pressure fluctuations encountered when the system is left open to the normal atmosphere. Measurements with bovine serum albumin at concentrations of 86 mg/ml (1.3 mM) were made with an absolute error of ±15% and standard error of ±5% in the pressure difference of 0.0032 cm of water. The molecular weight of this protein was determined to within ±0.4% of the value known from the amino acid sequence. The design presented here facilitates sample changes and requires less than one milliliter of solution per measurement.

ISSN:0034-6748    

DOI:10.1063/1.1136611

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We have constructed an eddy current shielded room from high‐conductivity aluminum sheets, 1.88 cm thick. A series of measurements designed to test the performance of the room has been carried out. The results of the measurements have been compared with theoretical predictions and also with the results from similar rooms reported in the literature. In some respects the agreement is good while in other respects considerable discrepancy exists. The response time of the room to a uniform field was found to be in good agreement with theory, whereas the response to a nonuniform field was found to be much worse. We also found that the room does not shield the vertical field component as well as the horizontal components. We give the reason for this and suggest a possible solution.

ISSN:0034-6748    

DOI:10.1063/1.1136612

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An electrical method for the adjustment of an electron beam without optical accessories is described. This method also allows a determination of the beam diameter, the axial brightness, and the astigmatism.

ISSN:0034-6748    

DOI:10.1063/1.1136613

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The thermal conductivity and specific heat of the glass–cloth reinforced epoxy laminate G‐10, as well as the cryogenic grade G‐10 CR, have been measured over the temperature range 0.1–4 K.

ISSN:0034-6748    

DOI:10.1063/1.1136614

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We describe a tunable low‐frequency Electron Spin Resonance spectrometer suitable for operation in the liquid helium temperature range. The resonator is a one‐quarter wavelength piece of stripline, whose frequency can be set anywhere in the band from 1–1.8 GHz. The microwave bridge uses a solid‐state oscillator and commerically available components.

ISSN:0034-6748    

DOI:10.1063/1.1136615

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A solar spectrophotometer with a dioptric imaging system linked to the monochromator by an optical fiber affords a lightweight, easily movable setup for the use in remote locations. Such a system is described in this note.

ISSN:0034-6748    

DOI:10.1063/1.1136616

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Design of an oven suitable for atomic spectroscopy experiments on low vapor pressure elements is described. This oven can heat samples to about 1000 °C without producing significant magnetic fields, without condensation of the sample along optical paths, and with very little optical background.

ISSN:0034-6748    

DOI:10.1063/1.1136617

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A solid–liquid separation filter has been adapted to transfer a filtered liquid directly to a volumetric flask. Time savings of approximately 50%, as compared to the conventional method, can be achieved.

ISSN:0034-6748    

DOI:10.1063/1.1136618

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A compact electroopticallyQ‐switched waveguide CO2laser, with the electrooptic crystal mounted within the waveguide, has been built and operated. Unlike most electroopticallyQ‐switched CO2lasers, it requires neither intracavity wavelength selection, nor a polarizing element, nor a waveplate.

ISSN:0034-6748    

DOI:10.1063/1.1136619

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A numerical procedure for differentiating current/voltage data of electronic devices is discussed within the framework of an example that uses a Pb–PbO–Pb superconducting tunnel junction. The derivative is obtained from measured values of current and voltage by a combination of numerical integration and digital filtering. Advantages are that the data can be acquired rapidly and the filtering time constant can be adjusted during the analysis, which is not performed in real time.

ISSN:0034-6748    

DOI:10.1063/1.1136620

出版商:AIP    

年代:1981

数据来源: AIP