Pub Date : 1989-11-01DOI: 10.1088/0022-3735/22/11/010
P. McDonald, P. Tokarczuk
A multiple pulse NMR line narrowing sequence which can be used with sinusoidally driven magnetic field gradients for the NMR imaging of solids and other short T2 materials is described. The sequence is shown to work experimentally with two-dimensionally cross-sectional images of sculptured rubber and Teflon samples.
{"title":"An NMR multiple pulse sequence for the imaging of solids using sinusoidally driven magnetic field gradients","authors":"P. McDonald, P. Tokarczuk","doi":"10.1088/0022-3735/22/11/010","DOIUrl":"https://doi.org/10.1088/0022-3735/22/11/010","url":null,"abstract":"A multiple pulse NMR line narrowing sequence which can be used with sinusoidally driven magnetic field gradients for the NMR imaging of solids and other short T2 materials is described. The sequence is shown to work experimentally with two-dimensionally cross-sectional images of sculptured rubber and Teflon samples.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"18 1","pages":"948-951"},"PeriodicalIF":0.0,"publicationDate":"1989-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88323026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-11-01DOI: 10.1088/0022-3735/22/11/014
M. Limon, C. Marchioni, G. Sironi
The authors describe a cold source operating at liquid helium temperature, used for absolute calibrations during radioastronomical observations at 600 MHz and 2500 MHz. Made with commercial dummy loads and coaxial cables in a standard Dewar bottle, it operates both at liquid helium and liquid nitrogen temperatures. A procedure for measuring the effective noise temperature of the source is described.
{"title":"An absolute cold reference for measurements at UHF and in the microwave band","authors":"M. Limon, C. Marchioni, G. Sironi","doi":"10.1088/0022-3735/22/11/014","DOIUrl":"https://doi.org/10.1088/0022-3735/22/11/014","url":null,"abstract":"The authors describe a cold source operating at liquid helium temperature, used for absolute calibrations during radioastronomical observations at 600 MHz and 2500 MHz. Made with commercial dummy loads and coaxial cables in a standard Dewar bottle, it operates both at liquid helium and liquid nitrogen temperatures. A procedure for measuring the effective noise temperature of the source is described.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"11 1","pages":"963-966"},"PeriodicalIF":0.0,"publicationDate":"1989-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81906503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-11-01DOI: 10.1088/0022-3735/22/11/011
J. Burt, T. A. Al-Ameen, R. Pethig
An optical system is described for measuring the response of suspended particles to imposed non-uniform electric fields in the frequency range 1 Hz to 4 MHz. Such dielectrophoretic measurements can provide details of the dielectric and surface charge properties of animate and inanimate particles. This simple, low-cost and rapid technique extends these measurements down to lower frequencies than previously reported, and has revealed new effects associated with particle surface charge and surface conductivity. At the lower frequencies corrections are required to take account of the electrode polarisation effects, which modify the electric field distribution in the colloidal suspension between the electrodes. Measurements are reported for silicon powder, yeast and the bacteria Micrococcus lysodeikticus and are compared with theoretical expectations. Biotechnological applications include cell separation, cell characterisation, cell-culture quality control and biomass determination.
{"title":"An optical dielectrophoresis spectrometer for low-frequency measurements on colloidal suspensions","authors":"J. Burt, T. A. Al-Ameen, R. Pethig","doi":"10.1088/0022-3735/22/11/011","DOIUrl":"https://doi.org/10.1088/0022-3735/22/11/011","url":null,"abstract":"An optical system is described for measuring the response of suspended particles to imposed non-uniform electric fields in the frequency range 1 Hz to 4 MHz. Such dielectrophoretic measurements can provide details of the dielectric and surface charge properties of animate and inanimate particles. This simple, low-cost and rapid technique extends these measurements down to lower frequencies than previously reported, and has revealed new effects associated with particle surface charge and surface conductivity. At the lower frequencies corrections are required to take account of the electrode polarisation effects, which modify the electric field distribution in the colloidal suspension between the electrodes. Measurements are reported for silicon powder, yeast and the bacteria Micrococcus lysodeikticus and are compared with theoretical expectations. Biotechnological applications include cell separation, cell characterisation, cell-culture quality control and biomass determination.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"21 1","pages":"952-957"},"PeriodicalIF":0.0,"publicationDate":"1989-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84416887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-11-01DOI: 10.1088/0022-3735/22/11/002
Cao Linxiang
The multistep error separation technique is a high precision measuring technique. It is widely used to measure the radial, axial and composite errors of rotating pick-up roundness measuring instruments, turntable roundness measuring instruments or precision axis systems. The author deals with the problems of measuring accuracy of the multistep method and the determination of the required number of sampling points. Theoretical analysis and experimental verification are presented.
{"title":"The measuring accuracy of the multistep method in the error separation technique","authors":"Cao Linxiang","doi":"10.1088/0022-3735/22/11/002","DOIUrl":"https://doi.org/10.1088/0022-3735/22/11/002","url":null,"abstract":"The multistep error separation technique is a high precision measuring technique. It is widely used to measure the radial, axial and composite errors of rotating pick-up roundness measuring instruments, turntable roundness measuring instruments or precision axis systems. The author deals with the problems of measuring accuracy of the multistep method and the determination of the required number of sampling points. Theoretical analysis and experimental verification are presented.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"1 1","pages":"903-906"},"PeriodicalIF":0.0,"publicationDate":"1989-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90666074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-11-01DOI: 10.1088/0022-3735/22/11/012
S. Sarma, B. M. Reddy, E. Rao, M. Rao, K. N. Sarebahi, A. K. Verman
The authors describe the design considerations of an airborne solid state digital microwave refractometer and present some sample results obtained with the instrument onboard a Cessna aircraft. Such data are expected to yield fine-structure information on the radio refractive index over tropical regions and help in understanding the microphysics of the tropical troposphere and in designing radio systems in the centimetre and millimetre waves. The instrument, operating at 9.341 GHz, has a stability of 10-7 degrees C-1 and a sensitivity better than 1 N unit with a dynamic range of 0-400 N units. The results have demonstrated convincingly the utility of the technique in obtaining the vertical profile of radio refractivity, especially in a turbulent medium.
{"title":"Design of airborne solid state digital microwave refractometer for use in the tropics","authors":"S. Sarma, B. M. Reddy, E. Rao, M. Rao, K. N. Sarebahi, A. K. Verman","doi":"10.1088/0022-3735/22/11/012","DOIUrl":"https://doi.org/10.1088/0022-3735/22/11/012","url":null,"abstract":"The authors describe the design considerations of an airborne solid state digital microwave refractometer and present some sample results obtained with the instrument onboard a Cessna aircraft. Such data are expected to yield fine-structure information on the radio refractive index over tropical regions and help in understanding the microphysics of the tropical troposphere and in designing radio systems in the centimetre and millimetre waves. The instrument, operating at 9.341 GHz, has a stability of 10-7 degrees C-1 and a sensitivity better than 1 N unit with a dynamic range of 0-400 N units. The results have demonstrated convincingly the utility of the technique in obtaining the vertical profile of radio refractivity, especially in a turbulent medium.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"7 1","pages":"958-961"},"PeriodicalIF":0.0,"publicationDate":"1989-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89730338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-10-01DOI: 10.1088/0022-3735/22/10/010
O. Sueoka, M. Yamazaki
A method for narrowing the energy width of e+ and e- beams using a 22Na radio-isotope and a W moderator is developed. The method provides a width of about 1 eV for 10-20 eV beams, and is applied to inelastic scattering measurements on the Schumann-Runge excitation of an O2 molecule by e+ and e- impact. The ratio of the excitation cross section in O2 by e+ impact to that by e- is about 1.2 for impact energies in the range 13-22 eV.
{"title":"Method for narrowing energy width of e+ and e− beams in a TOF system","authors":"O. Sueoka, M. Yamazaki","doi":"10.1088/0022-3735/22/10/010","DOIUrl":"https://doi.org/10.1088/0022-3735/22/10/010","url":null,"abstract":"A method for narrowing the energy width of e+ and e- beams using a 22Na radio-isotope and a W moderator is developed. The method provides a width of about 1 eV for 10-20 eV beams, and is applied to inelastic scattering measurements on the Schumann-Runge excitation of an O2 molecule by e+ and e- impact. The ratio of the excitation cross section in O2 by e+ impact to that by e- is about 1.2 for impact energies in the range 13-22 eV.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"13 1","pages":"852-855"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88722863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-10-01DOI: 10.1088/0022-3735/22/10/015
H. S. Vora, T. N. Das, V. Kumar, M. N. Kumbhare, R. Koul
The digital photometer system developed earlier has been upgraded by incorporating a microprocessor-based system with it. The optical response of the system is uniform in the detection range of 250-1100 nm. The associated non-linearity of measurements of high irradiance has also been removed by suitable circuit modifications. The system is now capable of storing time profiles of photometric data and has enhanced user-friendly options.
{"title":"DESIGN NOTE: Microprocessor-based 250-1100 nm photometer with flat spectral response","authors":"H. S. Vora, T. N. Das, V. Kumar, M. N. Kumbhare, R. Koul","doi":"10.1088/0022-3735/22/10/015","DOIUrl":"https://doi.org/10.1088/0022-3735/22/10/015","url":null,"abstract":"The digital photometer system developed earlier has been upgraded by incorporating a microprocessor-based system with it. The optical response of the system is uniform in the detection range of 250-1100 nm. The associated non-linearity of measurements of high irradiance has also been removed by suitable circuit modifications. The system is now capable of storing time profiles of photometric data and has enhanced user-friendly options.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75744663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-10-01DOI: 10.1088/0022-3735/22/10/008
F. Clarke, J. Leonard
The authors describe the experimental evaluation of an image processing algorithm which provides radiometric restoration and calibration. Using this technique, the response of a modified TICM II thermal imager to a test field is related, pixel by pixel, to the corresponding responses to two calibrated reference fields having different radiances. Systematic spatial variations of responsivity arising from defects in image formation, scanning, detection and electronic processing are removed to the limits of precision imposed by noise, stability and roundoff. The algorithm can also be applied to other fields of quantitative imaging.
{"title":"Radiometric image restoration and calibration for thermal and other video images","authors":"F. Clarke, J. Leonard","doi":"10.1088/0022-3735/22/10/008","DOIUrl":"https://doi.org/10.1088/0022-3735/22/10/008","url":null,"abstract":"The authors describe the experimental evaluation of an image processing algorithm which provides radiometric restoration and calibration. Using this technique, the response of a modified TICM II thermal imager to a test field is related, pixel by pixel, to the corresponding responses to two calibrated reference fields having different radiances. Systematic spatial variations of responsivity arising from defects in image formation, scanning, detection and electronic processing are removed to the limits of precision imposed by noise, stability and roundoff. The algorithm can also be applied to other fields of quantitative imaging.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"39 1","pages":"841-849"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84092440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-10-01DOI: 10.1088/0022-3735/22/10/011
J. Pouget, J. Mugnier, B. Valeur
In frequency-domain fluorometry, the phase shift and relative modulation are measured with respect to a reference solution. Systematic timing errors can be avoided if a fluorophore of known lifetime is used as a reference. However, this reference fluorophore must fulfil several stringent requirements which are not always met by common reference fluorophores. The authors suggest an alternative method in which the measurements of phase shift and relative modulation are performed by using a scattering suspension as a reference, and the systematic phase errors are corrected afterwards thanks to a separate calibration of the instrument. Such a calibration is possible because it is demonstrated that the timing errors result in a frequency-independent time shift. The value of this time shift can be readily determined by analysis of the phase and modulation values obtained with a fluorophore which is excitable and observable at wavelengths comparable with those used in the experiment to be performed. No previous knowledge of the lifetime is required. The validity of this method is demonstrated by the resolution of closely spaced two-component decays and by the determination of very short lifetimes.
{"title":"Correction of systematic phase errors in frequency-domain fluorometry","authors":"J. Pouget, J. Mugnier, B. Valeur","doi":"10.1088/0022-3735/22/10/011","DOIUrl":"https://doi.org/10.1088/0022-3735/22/10/011","url":null,"abstract":"In frequency-domain fluorometry, the phase shift and relative modulation are measured with respect to a reference solution. Systematic timing errors can be avoided if a fluorophore of known lifetime is used as a reference. However, this reference fluorophore must fulfil several stringent requirements which are not always met by common reference fluorophores. The authors suggest an alternative method in which the measurements of phase shift and relative modulation are performed by using a scattering suspension as a reference, and the systematic phase errors are corrected afterwards thanks to a separate calibration of the instrument. Such a calibration is possible because it is demonstrated that the timing errors result in a frequency-independent time shift. The value of this time shift can be readily determined by analysis of the phase and modulation values obtained with a fluorophore which is excitable and observable at wavelengths comparable with those used in the experiment to be performed. No previous knowledge of the lifetime is required. The validity of this method is demonstrated by the resolution of closely spaced two-component decays and by the determination of very short lifetimes.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"21 1","pages":"855-862"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72684949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-10-01DOI: 10.1088/0022-3735/22/10/016
C. E. Bassey, J. J. Fletcher
A penetrameter, which is a device for checking the kVp calibration of an X-ray generator, has been designed and constructed in the University of Ilorin using locally available materials. The device consists of a 2 mm thick sheet of aluminium used as a beam hardener, stacks of various numbers of aluminium discs for beam attenuation, Perspex for support and an X-ray film cassette for detection. The identification of dots of equal optical density is made using a densitometer also made by one of the authors. The device has been tested in the Radiology department of the University of Ilorin Teaching Hospital on a diagnostic range X-ray machine and found to be satisfactory. It is simpler and less expensive than imported penetrameter cassettes.
{"title":"A simple penetrameter","authors":"C. E. Bassey, J. J. Fletcher","doi":"10.1088/0022-3735/22/10/016","DOIUrl":"https://doi.org/10.1088/0022-3735/22/10/016","url":null,"abstract":"A penetrameter, which is a device for checking the kVp calibration of an X-ray generator, has been designed and constructed in the University of Ilorin using locally available materials. The device consists of a 2 mm thick sheet of aluminium used as a beam hardener, stacks of various numbers of aluminium discs for beam attenuation, Perspex for support and an X-ray film cassette for detection. The identification of dots of equal optical density is made using a densitometer also made by one of the authors. The device has been tested in the Radiology department of the University of Ilorin Teaching Hospital on a diagnostic range X-ray machine and found to be satisfactory. It is simpler and less expensive than imported penetrameter cassettes.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"30 1","pages":"882-883"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85787196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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