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Fractal Description Of Electron Scattering In Solids: Several New Results And A Simple Modelization Of The Fractal Dimension, Raynald Gauvin, Dominique Drouin

Scanning Microscopy

The fractal behaviour of electron scattering in solids is studied with electron trajectories simulated by Monte Carlo simulations. More precisely, the Hausdorff-Besicovitch dimension is determined for several electrons trajectories simulated in solids of different compositions. Then, a simple model to compute the fractal dimension of electron trajectories in solids is presented, a model which raises a question concerning the maximum value of the backscattering coefficient. Results of Monte Carlo simulations of electron trajectories in several elements with total randomness for the polar and azimuthal angles of scattering are presented as a tentative answer to this question. Finally, the multi fractal …

Efficiency Of The Secondary Electron Detector In The Scanning Electron Microscope, Zbigniew Czyzewski, David C. Joy

Scanning Microscopy

The efficiency of the secondary electron detector in the scanning electron microscope (SEM) is one of the most important factors affecting the imaging process of the SEM. To compute the detector efficiency, the electrostatic field inside a specimen chamber must be known. A simple way of performing such calculations is to use a spreadsheet program which has a built-in capability of storing and performing some operations on three-dimensional matrices. Using a spreadsheet program makes it possible to solve the Laplace equation and calculate electron trajectories in geometrically complex electrostatic fields. This technique is applied to the estimation of detector efficiency …

Energy Loss Function And Source Function For Au 4f Photoelectrons Derived By Monte Carlo Analysis Of Reflection Electron Energy Loss Spectroscopy (Reels) And X-Ray Photoelectron Spectroscopy (Xps) Spectra, H. Yoshikawa, T. Tsukamoto, R. Shimizu

Scanning Microscopy

We have derived the energy loss function of Au for 1 keV electrons by Monte Carlo analysis of the reflection electron energy loss spectroscopy (REELS) spectra. This energy loss function was significantly different from the optical loss function widely used and has revealed that the surface excitation affects the energy loss spectrum of keV electrons.

X-ray photoelectron spectroscopy (XPS) background subtraction has been recently developed by using the energy loss function derived from the transmission electron energy loss spectroscopy (TEELS). We have demonstrated that the energy loss function derived from REELS has enabled a more accurate Au 4f XPS spectrum …

A Survey Of Electron Probe Microanalysis Using Soft Radiations: Difficulties And Presentation Of A New Computer Program For Wavelength Dispersive Spectrometry, M. Fialin, J. Hénoc, G. Remond

Scanning Microscopy

This paper aims to demonstrate that on-line peak integral technique with wavelength dispersive spectroscopy (WDS) provides accurate results with intensity measurement counting times as short as one or two minutes, owing to the high counting rates obtained with multilayer analyzers. A great advantage of a new computer program using this technique (available on SUN/UNIX work-stations operating Cameca SX-50 microprobes) consists in the original way that peak overlaps are treated. For each analytical point, overlapping counts emerging from an element B (B counts) are removed on-line from the measured raw counts in order to obtain the net counts corresponding to the …

Standardless Quantitative Analysis By X-Ray Spectrometry, János L. Lábár

Scanning Microscopy

Errors in standardless analysis arise from inaccuracies in atomic data, detection efficiency of the detector, the normalization and the sensitivity to the errors of the spectrum processing, and ZAF correction (which converts the ratio of the measured intensities into concentration). Other sources of error encountered in fully quantitative analysis (using standards) also remain in the standardless version. Calculation of the L_α standard intensities also requires incorporation of non-radiative transitions. Both the experimentally found dependence of the net L_α intensities on the atomic number and the corresponding peak-to-background ratios (P/B) indicate that an empirical increase in the …

Contrast Mechanism Of Scanning Tunneling Microscopy: The Two-Sided Point Of View, C. Julian Chen

Scanning Microscopy

It has been known for three decades that tunneling experiments should be explained by the electronic structures of both electrodes. Scanning tunneling microscopy (STM) is no exception. Since the development of STM in the early 1980s, experimental facts have repeatedly shown the necessity to explain the STM images and tunneling spectra from a two-sided point of view. In other words, the STM images and tunneling spectra should be explained by the interaction of the electron density distributions of the tip and the sample (in energy and space). In the early years of STM, due to a scarceness of experimental …

Distribution And Intracellular Localization Of Titanium In Plants After Titanium Treatment, G. Kelemen, A. Keresztes, E. Bacsy, M. Feher, P. Fodor, I. Pais

Food Structure

The physiological role of titanium in plants has not been elucidated yet, but a higher rate of growth , greater chlorophyll content and higher productivity, among others , may be attributed to this element. We have investigated the distribution of titanium in wheat seedlings after Titavit (a Ti ·ascorbate containing plant conditioner) treatment applied either through the leaf or through the root. In field experiments, we also sprayed spinach plants with Titavit. We have found a practically unidirectional tran slocation of Ti from the shoot into the root, and a preferential local ization of Ti in the nuclear cell fraction …

Structure And Composition Of Apple Juice Haze, T. Beveridge, V. Tait

Food Structure

Haze obtained from commercial apple juice over the 1991 season contained from 11.4 to 29.0% protein (w/w) , trace quantities of both metal cations and polymeric carbohydrate, and gave strong responses to tests for phenolic compounds indicating a protein-phenol haze. SDS-PAGE of the 2-mercaptoethanol reduced , guanidinium hydrochloride dissaggregated haze particles gave a continuous smear indicating a population of molecules ranging from 29K to greater than 205K daltons. Transmission electron microscopy of negatively stained preparations revealed the presence of spherical bodies only partially penetrable by stain and possessin g a suhunit structure. These particles were embedded in a material presumably …

Social Assessment Of The Options, Steven E. Daniels

Sociology, Social Work and Anthropology Faculty Publications

No abstract provided.

Organic Extracellular Matrix Components At The Bone Cell/Substratum Interface, X. Shen, E. Roberts, S. A. F. Peel, J. E. Davies

Cells and Materials

We have recently shown that differentiating bone cells are capable of elaborating, in vitro, a calcified matrix at the interface with several non-biological substrata which is similar to cement lines found in remodelling bone tissue. From previous morphological observations, this matrix appeared free of assembled collagen fibres which indicated that osteogenic cells produce an initial mineralized matrix before overt collagen fibre production. In the work reported herein, we used six antibodies to extracellular matrix components and two conjugates of secondary antibody, fluorescein and colloidal gold, to initiate a preliminary characterization of the organic components at the bone cell substratum …

The Peo/Pbt Copolymer-Mineralized Matrix Interface In Vitro, A. M. Radder, J. E. Davies, H. Leenders, C. A. Van Blitterswijk

Cells and Materials

Previous implantation experiments have investigated the interaction between a series of PEO/PBT copolymers (Polyactive®) and bone tissue, and shown the morphology of bone-bonding with several PEO/PBT ratios. However, the underlying mechanism of bone-bonding remains largely unknown. Therefore, an in-vitro approach was chosen to obtain more information on the events occurring at the PEO/PBT copolymer-bone interface. Rat marrow cells were cultured on two PEO/PBT copolymer proportions: a 60/40 ratio which is known to bond with bone tissue in-vivo and a 30170 ratio which, within one year of implantation, does not bond with bone. Evaluation was performed with light microscopy, scanning, backscatter …

Ash/Lilac Borer, Jay B. Karren

All Archived Publications

No abstract provided.

What Are The Indirect Costs Of Pesticide Use?, Ted Evans

All Archived Publications

No abstract provided.

Pea Aphid Outbreaks Associated With Spraying For The Alfalfa Weevil In Utah, Ted Evans, Jay B. Karren, Clyde Hurst

All Archived Publications

No abstract provided.

Cereal Leaf Beetle, Jay B. Karren

All Archived Publications

No abstract provided.

Zion Canyon Headquarters, Zion National Park, Utah, Draft Development Concept Plan, Environmental Assessment, United States Department Of The Interior, National Park Service

All U.S. Government Documents (Utah Regional Depository)

The study area, referred to as the headquarters area, incorporates the area from the south entrance station north to the Zion Canyon bridge. This includes the visitor center, the Watchman and South campgrounds, the amphitheaters, the nature center, the Oak Creek, Watchman, and Pine Creek residential areas, and the Oak Creek maintenance area. The study area encompasses approximately 325 acres. It includes a development zone (107 acres) and a natural zone (218 acres), and is surrounded by a proposed wilderness subzone.

Price - San Rafael Rivers Unit, Utah, Planning Report / Final Environmental Impact Statement, Colorado River Water Quality Improvement Program / Colorado River Salinity Control Program, United States Department Of The Interior, Bureau Of Reclamation And United States Department Of Agriculture, Soil Conservation Service

All U.S. Government Documents (Utah Regional Depository)

This integrated Planning Report/Final Environmental Impact Statement (PR/FEIS) presents an analysis of the planning process and the environmental impacts of the proposed Price-San Rafael Rivers Unit (Unit) of the Colorado River Water Quality Improvement Program (CRWQIP) and the Colorado River Salinity Control Program (CRSC). The document has been jointly prepared by the Bureau of Reclamation (Reclamation) and the Soil Conservation Service (SCS) to address the full range of potential environmental impacts, in compliance with the National Environmental Policy Act (NEPA). The CRWQIP/CRSC programs provide for projects upstream of Imperial Dam (near Yuma, Arizona, on the Arizona-California border) that are necessary …

Diamond Mountain Resource Area Resource Management Plan And Environmental Impact Statement, Volume Ii, United States Bureau Of Land Management

All U.S. Government Documents (Utah Regional Depository)

During the comment period January 3 through April 1, 1992, 286 letters were received on the Draft Diamond Mountain Resource Management Plan and Environmental Impact Statement. However, Several letters were received after the comment period closed and too late to be individually responded to in this document. The concerns and issues raised in these letters have been expressed in other comment letters which have been responded to and which are reprinted here.

Final Environmental Impact Statement Moyer Salt Timber Sale, United States Forest Service

Final Environmental Impact Statements (ID)

This Final Environmental Impact Statement documents the analysis of the effects of the proposed timber harvesting and related road construction in the 15,360 acre Moyer Salt Analysis Area. The proposed actions are designed to help achieve the silvicultural goals and objectives of the 1988 Salmon National Forest Land and Resource Management Plan (Forest Plan).

Interfacial Interactions, Competitive Adsorption And Emulsion Stability, Jianshe Chen, Eric Dickinson, Graeme Iveson

Food Structure

Food emulsion stability is strongly influenced by the interactions in the adsorbed layer around emulsion droplets. Competitive adsorption of pure milk proteins (13-casein or 13 -lactoglobulin) with nonionic surfactants in oil-in-water emulsions is shown to depend on the age of the adsorbed protein layer. Evidence is presented for slow accumulation of protein at the oil-water interface and/or partition of protein into the oil phase of emulsion droplets containing oil-soluble surfactant associated in reversed micelles. Small amounts of added water-soluble surfactant or calcium ions are shown to have a pronounced effect on the droplet coalescence rate under turbulent shear flow conditions. …

Mechanisms Of Hard-To-Cook Defect In Cowpeas: Verification Via Microstructure Examination, Keshun Liu, Yen-Con Hung, R. Dixon Phillips

Food Structure

It has been hypothesized that part of the hard-to-cook (HTC) defect in cowpeas is due to decreases in solubility and thermal stability of intracellular proteins during storage since coagulated proteins would limit water to starch and prevent full swelling during cooking. To verify this hypothesis, effects of soaking and heating temperature on texture, water absorption, protein water extractability and microstructure of control and HTC cowpea seeds (aged or treated) were studied. Scanning electron microscopy showed no structural difference between dry control and dry aged seeds. However, after soaking, in contrast to the control, aged seeds exhibited a coarse protein matrix …

An Apparatus For A New Microcube Encapsulation Of Fluid Milk In Preparation For Transmission Electron Microscopy, M. C. Alleyne, D. J. Mcmahon, N. N. Youssef, S. Hekmat

Food Structure

A simple apparatus has been developed for a new "microcube" encapsulation of fluid milk samples in their prefixation preparation for electron microscopy. The new technique is based on making cubic wells in an agar gel layer, filling them with fluid milk samples, and sealing them with another agar gel layer . The individual wells are then separated by cutting from the initial block, providing 0.5 mm walls around the samples. The embedded material (milk, buttermilk, yogurt, etc.) is fixed, dehydrated , and embedded in a resin for transmission electron microscopy. The procedure is simpler, and more versatile, reliable, and reproducible …

A Comparative Study Of Normal And Hard-To-Cook Brazilian Common Bean (Phaseolus Vulgaris): Ultrastructural And Histochemical Aspects, Elisabeth Garcia, Franco M. Lajolo, Barry G. Swanson

Food Structure

Legume seeds stored under high temperature and humidity develop a texture defect known as hard-to-cook (HTC). Structural and histochemical characteristics of normal and HTC beans (Phaseolus vulgaris) were studied after storing them at 5°C/40% relative humidity (RH) or 40°C/75% RH for 60 days. Cotyledonary cells of HTC beans showed contraction of the cell content, whereas the cytoplasm of normal seeds occupied the total cell volume. Cell walls of HTC beans appear more compact, showing smaller intercellular spaces. In normal beans the cell walls of adjacent cells had larger spaces between them. Pectic material of sections of hard beans stained more …

Microstructural Studies In Fat Research, I. Heertje

Food Structure

Microstructural studies play an important role in establishing the relation between composition, processing and final properties of many food products. In order to arrive at a full description of microstructure many visualization- and preparation techniques are needed. A number of fatty products such as shortenings, margarine , butter, and low fat spreads are discussed from a microstructural point of view. Examples of the influence of process parameters on microstructure and rheological properties are given. In particular, attention is paid to the fat crystalline matrix and the emulsion structure.

Further, a new methodology is described making it possible to study interactions …

A Tutorial And Comprehensive Bibliography On The Identification Of Foreign Bodies Found In Food, D. F. Lewis

Food Structure

The paper presents a philosophical approach to the investigation of foreign body incidents in food. The suggested procedure has similarities with "key" procedures used for taxonomy. However, the wide diversity of materials encountered and the need to determine something of the history of the offending item demands modifications to this process. The categorisation may be made on instinct or experience, and appropriate confirmatory tests will be applied in the light of the initial categorisation. Cardinal rules are proposed: firstly , the receipt of the items should be well documented; and secondly, the initial observations should be as non-destructive as possible. …

A Simple Freeze Fracture Technique For Scanning Electron Microscopy Of Collagenous Biomaterials, David L. Christiansen, George Pins, Frederick H. Silver

Cells and Materials

A simple freeze fracture technique for the ultrastructural analysis of fragile collagenous biomaterials is presented. Following standard methods of preparation and dehydration, fragile biomaterials are fractured with a sharp blade attached to a modified slide hammer. The sliding mass imparts a sudden impact load on the frozen surface of the material , creating a distortion free cleavage plane across the material. More traditional methods including bending and cutting with scissors introduce artifacts indirectly associated with stress concentration produced by bending, and sample compression at the edges with cutting. The impact loading of the sample during fracture results in preservation of …

The Effect Of Peo Ratio On Degradation, Calcification And Bone Bonding Of Peo/Pbt Copolymer (Polyactive), C. A. Van Blitterswijk, J. V.D. Brink, H. Leenders, D. Baaker

Cells and Materials

In this study, we evaluated the effect of PEO/ PBT proportion on the behavior of a range of PEO/ PBT segmented copolymers (Polyactive) during subcutaneous and intrabony implantation in the rat. It was demonstrated that varying the PEO proportion affected degradation, calcification and bone-bonding. The PEO/PBT 70/30 and 60/40 showed extensive degradation after 1 year, PEO/PBT 55145 an intermediate degradation, and the 40/60 and 30170 copolymers showed little and hardly any degradation respectively. PEO content also affected the degree of calcification . PEO/PBT 70/30 showed extensive and early calcification whereas almost no calcification was seen with PEO/PBT 30170. Since calcified …

Characterization Of Bovine Osteoclasts On An Ionomeric Cement In Vitro, D. H. Szulczewski, U. Meyer, K. Moller, U. Stratmann, S. B. Doty, D. B. Jones

Cells and Materials

Primary bovine osteoclasts were obtained by an outgrowth method from bovine periosteum and cultured for 7 days on an ionomeric cement for biomaterial testing. Osteoclasts cultured on slices of bovine bone and on glass microscope cover-slides served as a control. The cells were characterised as osteoclasts by a number of tests. Osteoclasts showed positive staining for tartrate resistant acid phosphatase and reactivity with the antibodies 13C2 and 23C6, which react with the alphachain of the vitronectin receptor. Addition of salmon calcitonin to the culture medium led to sudden cessation of lamellipodial activity. The cells resorbed bone by making pits. In …

A Scanning Electron Microscope Study Of The Ultrastructural Organization Of Bone Mineral, F. B. Bagambisa, U. Joos, W. Schilli

Cells and Materials

Scanning electron microscopy (SEM) was used to study samples of lamellar bone at magnifications typical for the published transmission electron micrographs, to gain more insight into the three-dimensional ultrastructure of bone mineral. Untreated (whole bone) samples allowed an assessment of the degree of mineralization. Deproteinized samples revealed the ultrastructural form and organization of bone apatite to be a function of the extent to which collagen fibers were imbibed with mineral. Numerous parallel formations reminiscent of troughs, gutters, or furrows, pierced and traversed the mineralization front. These troughs showed varying diameters identifiable with collagen fibers, and were separated from one another …

The Effect Of Substratum Roughness On Osteoclast-Like Cells In Vitro, K. Gomi, J. D. De Bruijn, M. Ogura, J. E. Davies

Cells and Materials

Calcium phosphate powders were used to produce three groups of experimental substrata for the culture of primary rat bone marrow cells in conditions which permitted the survival and function of osteoclasts. Each of the three experimental groups were subdivided by differences in substratum surface roughness and following a culture period of 7 to 11 days, the culture units were stained for tartrate-resistant acid phosphatase activity. In all samples both small, sometimes mononuclear, and large multinucleate cells stained positive for tartrate-resistant acid phosphatase activity and the numbers and types of cells were quantified and statistically analyzed. Following histochemical staining the samples …