Microanalysis with a soft X ray scanning microprobe.
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Bone Diseases↗
Biomedical subjects
J Kirz
Publications and source records attributed to J Kirz.
Soft X-ray scanning microscopy: its practical use for elemental mapping at the NSLS U15 beamline.
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Bone and Bones↗
A dependence of the inclusive production of hadrons with high transverse momenta.
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Journal Article↗
Absorption microanalysis with a scanning soft X-ray microscope: mapping the distribution of calcium in bone.
This article describes the scanning transmission X-ray microscope operated at the National Synchroton Light Source. The application of the instrument to elemental analysis is detailed. In particular, qualitative results on the calcium distribution in human skull tissue are presented.
Bone and Bones↗
Specimen damage considerations in biological microprobe analysis.
In many biological materials radiation damage limits the resolution of the microanalytical measurement. To provide some perspective regarding the relative merits of different experimental arrangements, the dose to the specimen may be calculated using a simple model. While electron and proton probe X-ray microanalysis are found to involve heavy doses to the specimen, X-ray fluorescence, performed with a polarized, monochromatic X-ray probe, is the least destructive for the analysis of medium to heavy elements. For light elements (Z less than or equal to 20), electron energy loss spectroscopy or X-ray absorption microanalysis involve the lowest dose in most applications. Other advantages and limitations of the various techniques are also summarized.
Electron Probe Microanalysis↗
Potential operating region for ultrasoft x-ray microscopy of biological materials.
Calculations are presented which indicate an extensive suboptical region in the microscopy of biological materials in their natural state which is accessible to ultrasoft x-ray transmission microscopy. Throughout most of the region, radiation dosage levels to the specimen are lower than in electron microscopy.
Energy Transfer↗
Transmission microscropy of unmodified biological materials: comparative radiation dosages with electrons and ultrasoft x-ray photons.
The minimum radiation dosage in a specimen consistent with transmission microscopy at resolution d and specimen thickness t is calculated for model specimens resembling biological materials in their natural state. The calculations cover 10(4)-10(7) eV electrons and 1.3-90 A photons in a number of microscopy modes. The results indicate that over a considerable part of the (t,d)-plane transmission microscopy on such specimens can be carried out at lower dosage with photons than with electrons. Estimates of the maximum resolutions obtainable with electrons and photons, consistent with structural survival of the specimen, are obtained, as are data on optimal operating conditions for microscopy with the two particles.
Air↗
Mapping and measuring DNA to protein ratios in mammalian sperm head by XANES imaging.
We have used XANES imaging, which combines X-ray absorption near edge spectral features (XANES) with 50-nm-resolution X-ray microscopy, to examine the content and distribution of DNA and protein in mature sperm cells. Sperm nuclei from five different species of mammals were examined; these species were chosen for analysis because their sperm contain marked differences in their protamine 1 and protamine 2 contents. The data we've obtained for bull, stallion, hamster, and mouse sperm suggest that the total nuclear protein to DNA ratio is similar in the sperm of many eutherian mammals. Since protamine constitutes the majority of the sperm nuclear protein, these results indicate that the total protamine content of sperm chromatin must be constant among mammalian species, independent of the extent of expression of the protamine 2 gene.
Absorptiometry, Photon↗