摘要:

A digital AC voltammetric technique in which the perturbation signal is obtained from a computer-controlled analog function generator is described. This approach overcomes the limitation of the upper frequency inherent in computer generated sinusoidal signals. The measurement of the current at a constant phase angle of the input sine wave is facilitated by synchronizing the current digitization with the triggering of the function generator. The frequency of the sine wave is controlled by the computer, through the voltage-controlled-oscillator of the function generator. A program based on the Fast Fourier Transform (FFT) algorithm is used to extract the frequency information from the total cell current and to discriminate against charging current. All the components used in the instrumental design are commercially available.

ISSN:1073-9149    

DOI:10.1080/10739149208543737

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The design of an Infrared Vibrational Circular Dichroism (VCD) spectrometer, optimized in the 6 μm spectral region, is reported. This instrument employs design features similar to the ones described previously [Diem, et al., 1988] for a broadband dispersive VCD instrument, and a detector and optics selected specifically for operation between 1600 and 2000 cm−1. This instrument exhibits an enormous enhancement in sensitivity over our previous dispersive unit at significantly better spectral resolution. Representative VCD spectra of a number of biomolecules in the C=0 stretching vibration are presented.

ISSN:1073-9149    

DOI:10.1080/10739149208543738

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Using the recently proposed open-photoacoustic-cell (OPC) detection technique the thermal diffusivity of potato skin has been found. Skin samples were taken from potatoes that were grown on different soils. The measurements were carried out with samples that, after being removed from the potatoes, were left in the air for different periods of time. Apparently, the process of the dehydration/oxidation resulted not only in the expected shrinkage of skin layers but also entailed chemical and/or structural changes that have produced a noticeable decrease of the thermal diffusivity coefficient.

ISSN:1073-9149    

DOI:10.1080/10739149208543739

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Specific detection of ammonia present at trace level concentrations in a simulated atmosphere was attempted through the combined use of intermodulation CO2laser photoacoustic Stark spectroscopy and phase-sensitive detection at the sum and difference sidebands of the modulating laser and Stark electric fields. Results of experiments performed at both 10R(6) and 10R(8) laser lines indicate the signal dependence on the water vapor concentration present in the used gas mixture. Adhering of ammonia to the cell walls was found also to be a function of the amount of water vapor in the simulated atmosphere.

ISSN:1073-9149    

DOI:10.1080/10739149208543740

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Flow-based methods of analysis such as flow-injection analysis and sequential-injection analysis are being used increasingly in the automation of laboratory methods and for process analysis. Full exploitation of these techniques in automated modes of operation necessitates computer control and data acquisition. Although most commercial systems are microprocessor driven, flexibility is seldom built into the software, thereby severely limiting the ingenuity of the analysts in the use of these instruments in novel and imaginative applications. A software package is described which allows for easy automation of flow-based analysis systems. The emphasis in the design of this package has been on flexibility, with numerous user-selected options and a wide variety of features. Applications to laboratory and plant analysers are described.

ISSN:1073-9149    

DOI:10.1080/10739149208543741

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A method is described for computerizing a Raman spectrometer for data acquisition and control of the monochromator. The system is built using inexpensive commercial hardware, and software for photon counting and monochromator control. Integration is achieved with a modicum of user programming.

ISSN:1073-9149    

DOI:10.1080/10739149208543742

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1073-9149    

DOI:10.1080/10739149208543743

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1073-9149    

DOI:10.1080/10739149208543744

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1073-9149    

DOI:10.1080/10739149208543736

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor