Deep cementation in late quaternary sands near Westport, New Zealand

Soil Research ◽  
1989 ◽  
Vol 27 (2) ◽  
pp. 275 ◽  
Author(s):  
CW Ross ◽  
G Mew ◽  
CW Childs
Keyword(s):  
Induction Furnace ◽  
Late Quaternary ◽  
Land Development ◽  
Soil Series ◽  
X Ray ◽  
Field Techniques ◽  
Chemical Reagents ◽  
Rich Material ◽  
Cementing Material

Deeply cemented quartzofeldspathic and ilmenitic sands occur on and beneath uplifted late Quaternary marine terrace surfaces over wide areas south of Westport on the west coast of the South Island. These terraces are weakly dissected, but are mainly flat to rolling. Rainfall averages about 3000 mm per year. Present vegetation consists of pasture, scrub and rush/fern associations which have replaced podocarp forest. Cementation of sands has resulted in impeded drainage, limited rooting volumes for trees and crops, and other limitations to land development. Two soil series, Charleston and Marris, were studied, as they were distinguished by having different forms of cementation in the field. Techniques used to investigate cementation included the determination of Fe, Al and Si contents by extraction with standard chemical reagents, X-ray diffractometry to identify minerals of short-range order, SEM to examine microstructures, EDAX to determine elemental composition, and heating in an induction furnace to evaluate C content. Two apparent causes of cementation were identified, namely ferrihydrite in the Charleston soil, and allophane with humus-aluminium complexes in the Marris soil. Microstructures of sand cemented by these materials were clearly different. In the Charleston soil, iron-rich material coating sand grains and bridging between them is smooth and gel-like and has a fine globular appearance under high magnification. In the Marris soil, the cementing material has a rough-textured fibrous appearance. The contrasts in types of cementing agents are thought to be related to firstly, differences in physiography at time of formation and secondly, different drainage conditions related to topographic position.

scholarly journals The crystallographic and optical properties of iodo-succinimide

1925 ◽  
Vol 108 (747) ◽  
pp. 548-552 ◽  
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Optical Data ◽  
Circular Plates ◽  
X Ray ◽  
Usual Process ◽  
Cementing Material ◽  
First Time ◽  
Preceding Communication

During the progress of the X-ray research on this substance by Miss Yardley, the results of which are embodied in the preceding communication, the need for a thorough reinvestigation of the crystallographic and especially the optical properties of the substance, was made very clear. The difficulty as regards the optical constants was that of preparing the properly orientated and absolutely truly plane-surfaced section-plates and 60°-prisms of this relatively soft and fragile substance, and after many attempts of a really heroic nature Miss Yardley appealed to the author, who was only too pleased to bring into service his cutting-and-grinding goniometer, with which the necessary plates and prisms were successfully prepared. The author, however, becoming very interested in the substance, has carried out also a complete goniometrical remeasurement, in the light of the new and correct setting which Miss Yardley has indicated, and a determination of the density of the crystals, so that with the optical data, now given for the first time, a revised and much more complete crystallographic description is herewith given. It agrees in every respect with the conclusions of Miss Yardley, as described in the immediately preceding communication. The only real difficulty met with, which renders the substance unusual to deal with, is the fact that no cementing material has been found which is without action on iodo-succinimide. For instance, Canada balsam and its solution in benzene (a hydrocarbon which, very fortunately, does not act on iodo-succinimide) or turpentine at once turn deep brown to black when used to cement section-plates to cover-glasses or to the little circular plates of parallel glass which the author uses in the preparation of the second surface. So that, after the first surface of a section-plate has been ground, the crystal being held as usual on the crystal holder by opticians’ hard wax, any action not mattering much here, the usual process—of cementing the crystal by this first surface on to one of the little glass discs, fitting the latter into the receptacle for it in the parallel-plate, preparing fitting of the cutting-and-grinding goniometer, and grinding the second surface without further trouble and thus making a plate as thin as may be desired—cannot be employed with iodo-succinimide. To prepare the second surface the crystal must be reset goniometrically, while held in a grip-holder instead of the usual holder carrying opticians’ wax, and then ground and polished with great care to avoid slipping in the gripper. As the substance is soft and friable this is rather a nuisance, especially, moreover, as it was desirable to be able to obtain section-plates of considerable tenuity for the purposes of Laue photographic X-ray analysis, as well as very thick ones for the study of possible optical activity. Happily, however, all these unusual difficulties were eventually overcome, and the desired results obtained.

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

Polarity Determination in Sphalerite and Wurtzite Structures

1990 ◽  
Vol 48 (2) ◽  
pp. 500-501
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Opposite Polarity ◽  
Single Domain ◽  
Polar Material ◽  
Electron Microscopic ◽  
Dynamical Interaction ◽  
X Ray ◽  
Polarity Determination ◽  
The Absolute ◽  
Microscopic Techniques

The determination of the absolute polarity of a polar material is often crucial to the understanding of the defects which occur in such materials. Several methods exist by which this determination may be performed. In bulk, single-domain specimens, macroscopic techniques may be used, such as the different etching behavior, using the appropriate etchant, of surfaces with opposite polarity. X-ray measurements under conditions where Friedel’s law (which means that the intensity of reflections from planes of opposite polarity are indistinguishable) breaks down can also be used to determine the absolute polarity of bulk, single-domain specimens. On the microscopic scale, and particularly where antiphase boundaries (APBs), which separate regions of opposite polarity exist, electron microscopic techniques must be employed. Two techniques are commonly practised; the first [1], involves the dynamical interaction of hoLz lines which interfere constructively or destructively with the zero order reflection, depending on the crystal polarity. The crystal polarity can therefore be directly deduced from the relative intensity of these interactions.

Problems in Thin-Film X-ray Quantification

1990 ◽  
Vol 48 (2) ◽  
pp. 458-459
Author(s):  
J N Chapman ◽  
W A P Nicholson
Keyword(s):  
Thin Film ◽  
Specimen Thickness ◽  
X Rays ◽  
Characteristic Peak ◽  
Local Composition ◽  
X Ray ◽  
Measured Ratio ◽  
Path Lengths ◽  
Composition Changes

Energy dispersive x-ray microanalysis (EDX) is widely used for the quantitative determination of local composition in thin film specimens. Extraction of quantitative data is usually accomplished by relating the ratio of the number of atoms of two species A and B in the volume excited by the electron beam (nA/nB) to the corresponding ratio of detected characteristic photons (NA/NB) through the use of a k-factor. This leads to an expression of the form nA/nB = kAB NA/NB where kAB is a measure of the relative efficiency with which x-rays are generated and detected from the two species.Errors in thin film x-ray quantification can arise from uncertainties in both NA/NB and kAB. In addition to the inevitable statistical errors, particularly severe problems arise in accurately determining the former if (i) mass loss occurs during spectrum acquisition so that the composition changes as irradiation proceeds, (ii) the characteristic peak from one of the minority components of interest is overlapped by the much larger peak from a majority component, (iii) the measured ratio varies significantly with specimen thickness as a result of electron channeling, or (iv) varying absorption corrections are required due to photons generated at different points having to traverse different path lengths through specimens of irregular and unknown topography on their way to the detector.

Reduction of Potassium in Kidney Proximal Tubules to Aid in Electron Probe X-Ray Microanalysis of Calcium

1985 ◽  
Vol 43 ◽  
pp. 474-475
Author(s):  
A. LeFurgey ◽  
P. Ingram ◽  
L.J. Mandel
Keyword(s):  
Smooth Muscle ◽  
Proximal Tubule ◽  
Electron Probe ◽  
Clinical Applications ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Target Cells ◽  
X Ray ◽  
Freeze Dried

For quantitative determination of subcellular Ca distribution by electron probe x-ray microanalysis, decreasing (and/or eliminating) the K content of the cell maximizes the ability to accurately separate the overlapping K Kß and Ca Kα peaks in the x-ray spectra. For example, rubidium has been effectively substituted for potassium in smooth muscle cells, thus giving an improvement in calcium measurements. Ouabain, a cardiac glycoside widely used in experimental and clinical applications, inhibits Na-K ATPase at the cell membrane and thus alters the cytoplasmic ion (Na,K) content of target cells. In epithelial cells primarily involved in active transport, such as the proximal tubule of the rabbit kidney, ouabain rapidly (t1/2= 2 mins) causes a decrease2 in intracellular K, but does not change intracellular total or free Ca for up to 30 mins. In the present study we have taken advantage of this effect of ouabain to determine the mitochondrial and cytoplasmic Ca content in freeze-dried cryosections of kidney proximal tubule by electron probe x-ray microanalysis.

Determination of some heavy metals (Fe, Cu, Zn and Pb) in blood by total reflection X-ray fluorescence

2003 ◽  
Vol 107 ◽  
pp. 203-206 ◽  
Author(s):  
M. Bounakhla ◽  
A. Doukkali ◽  
K. Lalaoui ◽  
H. Aguenaou ◽  
N. Mokhtar ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Total Reflection ◽  
X Ray
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