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Global Climate Change Response Program, Water Yield In Semiarid Environment Under Projected Climate Change, United States Department Of The Interior

Water

This paper presents the practical application of a distributed parameter climate vegetation hydrologic model (CVHM) and its ability to simulate hydrologic response under existing conditions and under assumed CO₂-induced climate and vegetation change. Applying the model to the Weber River basin provided a basis for determining the impacts of climate change on the hydrologic response. By using a "what if" scenario this model included the changes in plant transpiration rates and in vegetation cover under a CO₂-altered climate change and the effects of these changes on water yield.

Development Of An Scanning Tunneling Microscopy-Based Electron Beam Induced Current (Ebic) Microscope, P. Koschinski, V. Dworak, P. E. West, L. J. Balk

Scanning Microscopy

Measurements of electron beam induced currents (EBIC) can either be performed in a scanning electron microscope (SEM) or in a scanning tunneling microscope (STM), since both microscopes are very similar in their basic assembly. However, a straightforward application of an STM in EBIC-measurements, i.e. the use of a microscope tip as a fine source for low energetic electrons is not possible due to the specific demands on the instrument in an EBIC application. The present paper gives a compilation of these demands and describes their conversion into an optimized STM-EBIC microscope.

Numerical Simulation Of The Influence Of Electron Beam Induced Excess Charge Carriers On Potential And Charge Carrier Density Distributions In Gaas Mesfet, K. Kaufmann, L. J. Balk

Scanning Microscopy

Such scanning electron microscopy modes as electron beam induced current (EBIC), cathodoluminescence (CL) and scanning electron acoustic microscopy (SEAM) are widely used for the characterization of semiconductor specimens and devices. These methods are based on the generation of excess charge carriers by an electron beam inside of the investigated specimen. Usually, theoretical models used to explain the physics of these methods presuppose the low injection case.

However, in experimental investigations, the low injection condition cannot always be observed. Thus, for the interpretation of such measurement results more complicated simulation models have to be used. Such simulations can be carried out …

Immunomicroscopy: Resin Techniques And On-Section Labelling With Immunocolloidal Gold Or Immunoperoxidase - Planning A Protocol, Jan A. Hobot, Geoffrey R. Newman

Scanning Microscopy

On-section immunocytochemistry is divided into two parts: (i) processing of biological tissue for section microscopy and (ii) immunolabelling of sections. Many of the more successful microscopical methods employ delicate aldehyde fixation of biological tissue followed by "sympathetic" processing into an acrylic resin. Processing regimens do not have to be complicated. Simple and cost effective room temperature protocols utilising partial dehydration have been devised and they can be as effective as the more complex low temperature techniques in preserving both ultrastructure and antigenic reactivity. The embedded material can be investigated by either light or electron microscopy. Frozen sections can be cut …

Studies On The Role Of Urinary Macromolecules In Urolithiasis: Review Of Methodologies And A Proposal For A Standard Reference Crystallization System, A. L. Rodgers, D. Jappie

Scanning Microscopy

In this study, urine from a calcium oxalate kidney stone former was ultrafiltered (10 kD cut-off). Crystallization was induced in the ultrafiltrate and retentate fractions as well as in a sample of the whole urine. The progress of crystallization was monitored by Coulter Counter and flow cytometry techniques. (The latter has not been used in studies of the role of urinary macro-molecules in urolithiasis). Deposited crystals were examined by scanning electron microscopy. Results indicated that urinary macromolecules in this subject are inhibitors of nucleation and aggregation. These results agree with the findings of some workers but disagree with those of …

The Role Of Defects In Semiconductor Materials And Devices, D. B. Holt

Scanning Microscopy

This literature review leads to the conclusion that recently the basis for an understanding of the electrical and optical properties of structural defects in semiconductors, especially in silicon, has begun to emerge. This is due largely to the ability of scanning electron microscopy (SEM) electron beam induced current (EBIC) and cathodoluminescence (CL) to determine the properties of single, well-defined defects in "state of the art" material. However, there are still major differences concerning the physical models to be used to explain different forms of dislocation EBIC contrast variation with temperature and beam current. Basic ideas in this field are emphasized. …

Multiple Labeling In Electron Microscopy: Its Application In Cardiovascular Research, M. M. H. Marijianowski, P. Teeling, K. P. Dingemans, A. E. Becker

Scanning Microscopy

The heart is a muscular pump kept together by a network of extracellular matrix components. An increase in collagens, as in chronic congestive heart failure (CHF), is thought to have a negative effect on cardiac compliance and, thus, on the clinical condition. Conventional electron microscopy allows for the study of cellular and extracellular components and scanning electron microscopy (SEM) can put these structures in three-dimensional perspective. However, in order to study extracellular matrix components in relation to cells, immunoelectron microscopy is superior. We have used this technique in our studies on heart failure. Heart specimens were fixed in 4% paraformaldehyde …

A Novel Method For Viewing Heavy Metal Stained And Embedded Biological Tissue By Field Emission Scanning Electron Microscopy, R. Geoffrey Richards, Iolo Ap Gwynn

Scanning Microscopy

Backscattered electron (BSE) imaging was used to display heavy metal stained biological structures of various embedded specimens. Samples were fixed, stained and embedded in resin blocks as with preparation for the transmission electron microscope (TEM). Blocks were trimmed to center the specimens in a trapezoidal face of up to 5 mm² and their sides painted with conductive silver paint leaving the face uncovered. Blocks were sputter coated with 6-8 nm of silver, chromium or aluminum, with aluminum providing the best specimen contrast in BSE mode. Samples were examined in a field emission scanning electron microscope operated at a high …

Demonstration Of The Fine Structure Of Stereocilia In The Organ Of Corti Of The Guinea Pig By Field Emission Scanning Electron Microscopy, W. L. Jongebloed, E. A. Dunnebier, F. W. J. Albers, D. Kalicharan

Scanning Microscopy

A combined perfusion- and immersion prefixation with glutaraldehyde followed by a tannic acid/arginine/osmium tetroxide (TAO) treatment of the guinea pig cochlea is described for field-emission gun scanning electron microscopy (FEG-SEM) observation of the fine structure of the stereocilia of the organ of Corti. Conventional osmium tetroxide postfixation methods in combination with a thin conductive coating failed to show the fine structure of the glycocalyx of the epithelial lining in the endolymphatic compartment of the cochlea, in particular, on the stereocilia surface. The antennulae-like glycocalyx covering of the stereocilia surface of the more pronounced rows of outer hair cells has been …

Urinary Stone Proteins: An Update, J. P. Binette, M. B. Binette, M. A. Gawinowicz, N. Kendrick

Scanning Microscopy

The discovery of an organic component in kidney stones dates back to 1684. More than 150 years elapsed before the incrustation of this organic component, which is now called the matrix, was proposed as the mechanism of stone formation. The composition of the matrix remained largely unknown until the development of electron microscopy and the advances in biochemistry combined in the 1950's to usher in the modern era of renal stone matrix investigation. Composed mainly of selectively incorporated proteins generally characterized by high glutamic and aspartic acid content and the frequent occurrence of y-carboxyglutamic acid, the matrix dis-plays a variable …

Neural Transplant Staining With Dii And Vital Imaging By 2-Photon Laser-Scanning Microscopy, Steve M. Potter, Jerome Pine, Scott E. Fraser

Scanning Microscopy

We are developing a multielectrode silicon "neuroprobe" for maintaining a long-term, specific, two-way electrical interface with nervous tissue. Our approach involves trapping a neuron (from an embryonic rat hippocampus) in a small well with a stimulation/ recording electrode at its base. The well is covered with a grillwork through which the neuron's processes are allowed to grow, making synaptic contact with the host tissue, in our case a cultured slice from a rat hippocampus. Each neuroprobe can accommodate 15 neurons, one per well. As a first step in studying neurite outgrowth from the neuroprobe, it was necessary to develop new …

Diffuse Neuroendocrine System: Structural And Functional Effects Of Radiation Injury To Amine Precursor Uptake And Decarboxylation (Apud) Cells, I. M. Kvetnoy, V. V. Yuzhakov, A. O. Molotkov, L. N. Bandurko, R. A. Brodsky, N. D. Yakovleva

Scanning Microscopy

The paper presents a review of the results obtained by the authors on the study of external (gamma) and internal (I-131) radiation effects on the functional morphology and linkage of the diffuse neuroendocrine system (DNES) and amine precursor uptake and decarboxylation (APUD) cells of the stomach and duodenum. The investigations performed enabled us to determine that the morphological changes noted in APUD cells had a dose and time dependency. The present study supports the point of view that the radiation initiates serotonin release from APUD cells, which appears to initiate the mechanism of early postirradiation dysfunctions of the gastrointestinal tract …

Specimen Preparation Of The Human Cerebellar Cortex For Scanning Electron Microscopy Using A T-Butyl Alcohol Freeze-Drying Device, Teruyuki Hojo

Scanning Microscopy

A freeze-drying device was applied to t-butyl alcohol substituted nerve cells, fibers and synaptic terminals. Ten percent formalin-fixed human cerebellar cortex specimens were postfixed in 2.5% glutaraldehyde in 0.1 M cacodylate buffer solution and were rinsed three times in 5% sucrose solution in the same buffer. After the postfixed specimens were dehydrated using a graded series of ethanols and then transferred into a graded series of t-butyl alcohols (freezing point 25.4°C), the t-butyl alcohol substituted specimens were freeze-dried at 15°C and at high vacuum (5x10^-2 Torr). The freeze-dried specimens were sputter coated with gold. Scanning electron …

Calcium Oxalate Crystallization In Urine Of Healthy Men And Women: A Comparative Study, Niels-P. Buchholz, Dong Sun Kim, Phulwinder K. Grover, Rosemary L. Ryall

Scanning Microscopy

This study aimed to compare calcium oxalate (CaOx) crystallization in undiluted urine from healthy men and women with the object of clarifying the difference in stone incidence between the two sexes. Twenty-four hour urine specimens were collected from 37 men and 28 women. Urinary pH, and concentrations of Ca, oxalate and urate were measured, and indices of crystallization determined by Coulter Counter particle analysis following induction of CaOx crystallization by addition of oxalate. The amount of oxalate required to induce crystallization was significantly (p < 0.01) higher in females than in males, as was the overall particle volume deposited after 90 minutes incubation (p < 0 .006). Scanning electron microscopy revealed larger individual crystals in female urine, and a greater degree of crystal aggregation in male urine, although the average overall size of the precipitated crystal particles did not differ between the two sexes. There were no significant differences between men and women with regard to median pH, or Ca and oxalate concentrations, but the median urate concentrations were slightly, but significantly, higher (p < 0.05) in the women's urines than in the men's. It was concluded that the greater risk of CaOx stones in men is related to an increased propensity to nucleate CaOx crystals per se, rather than to a tendency to form larger crystalline particles.

Laboratory Growth Systems In Biofilm Research, Julian W. T. Wimpenny

Cells and Materials

The huge variety of ecosystems that we collectively refer to as "biofilm" is reflected by the numerous different systems available to grow them in the laboratory. The relationship between in situ systems, microcosms and laboratory models is defined and discussed. The first two represent holistic approaches designed to assess the structure and function of particular biofilms: the last is analytical and reductionist, aiming to isolate specific functions of biofilms in order to understand properties that can apply to biofilm in general. Properties of a model can be completely understood whilst this is unlikely with natural ecosystems because of the possibility …

Initial Biodeterioration Of Silicone Rubber By C. Albicans And C. Aropicalis Strains Isolated From Voice Prostheses, H. C. Van Der Mei, B. Van De Belt-Gritter, F. Dijk, H. J. Busscher

Cells and Materials

Silicone rubber voice prostheses m patients after total laryngectomy become rapidly colonized by a biofilm, consisting of yeasts and bacteria. An especially troublesome feature of these biofilms is the ingrowth into the silicone rubber by colonizing yeasts. Microcolonies of ingrowing yeasts have been frequently observed on explanted voice prostheses after 3-4 months use. Incubation of silicone rubber samples in a modified Robbins device with a culture of Candida tropicalis, isolated from a Groningen button voice prosthesis, while passing the yeasts through a cycle of feasts (7 days) and famine (also 7 days) demonstrated, by electron microscopy, the onset of the …

Gap Junctional Intercellular Communication In Bone, Henry J. Donahue, Monique A. Vander Molen, Clare E. Yellowley, Zhongyong Li

Cells and Materials

Gap junctional intercellular communication has been demonstrated in bone cells and may contribute to the mechanism by which osteoblasts integrate and amplify extracellular signals, both chemical (hormonal) and biophysical (electrical and mechanical). Connexin 43 (Cx43) is the predominant gap junction protein expressed by bone cells. Experiments with osteoblastic cells in which Cx43 expression was diminished by antisense transfection demonstrate that cell-to-cell coupling in osteoblastic ROS 17/2.8 cells is via gap junctions composed of Cx43. Cellular networks of these coupling deficient clones are dramatically less responsive to parathyroid hormone (PTH) suggesting that coupling contributes to hormonal responsiveness. Furthermore, PTH per se …

Forest Resources Of Northern Utah Ecoregions, Renee A. O'Brien

Elusive Documents

No abstract provided.

How Long Until Crisis In African Wildlife Integrated Conservation And Development Projects (Icdps)? Simulation Results From The Serengeti Ecosystem, Christopher B. Barrett, Peter Arcese

Economic Research Institute Study Papers

This paper develops a model coupling species population dynamics with endogenous human consumption and poaching behavior in an environment of imperfect labor and product markets and static agricultural production technology subject to environmental shocks. Using the case of the Serengeti, we then simulate how integrated conservation and development projects (lCDPs) might effectively serve as a delaying tactic against biodiversity loss until a more durable solution can be found to the challenge of wildlife conservation lin the midst of endemic rural poverty.

Stability Of Liposomes Prepared From Archaeobacterical Lipids And Phosphatidylcholine Mixtures, G. D. Sprott, C. J. Dicaire, L. P. Fleming, G. B. Patel

Cells and Materials

In vitro stabilities of liposomes prepared from the total polar lipids (TPL) of various species of Archaeobacteria were compared with those made from egg phosphatidylcholine (EPC) and from mixtures of TPLIEPC. Stability was monitored by measuring the extent of leakage of entrapped dyes. Liposomes prepared from exclusively archaeobacteriallipids (coined archaeosomes), particularly those containing the bilayer spanning tetraether lipids, were generally stable to conditions such as storage at 37°C for greater than 7 days, exposure to phospholipase A₂, incubation with serum, and, to some extent, exposure to bile salts. In contrast, EPC liposomes were generally unstable to these conditions, …

Application Of Confocal Laser Scanning Microscopy To Cytocompatibility Testing Of Potential Orthopaedic Materials In Immortalised Osteoblast-Like Cell Lines, R. Macnair, R. Wilkinson, C. Macdonald, I. Goldie, D. B. Jones, M. H. Grant

Cells and Materials

Confocal laser scanning microscopy (CLSM) was used in conjunction with in vitro cell culture to investigate cellular interactions with orthopaedic biomaterials. Transfected rat and human osteoblasts were seeded on two potential isoelastic hip prosthesis materials, carbon fibre reinforced polyetheretherketone (PEEK) and epoxy. Titanium 318 alloy was employed as a control. Determination of the material surface contour, an important factor influencing cellular adhesion, proliferation and function, was performed using the industry standard Talysurf® and compared to analogous results obtained using the CLSM. The latter technique consistently gave higher values of material roughness but offers the advantage that it can be used …

Letter To The Editor: Biocompatibility And Reactogenicity Of Materials: A Semantic And Logical Analysis Of Definitions And Their Practical Significance, Leonid I. Slutskii, Janis J. Vetra

Cells and Materials

Any biomaterial implanted into a living body elicits a distinct local reaction. This reaction depends on the physical, physico-chemical and chemical properties of the material. The obvious term to designate this inherent property of a biomaterial to induce a local reaction is reactogenicity. Reactogenicity of a biomaterial is one of the main factors determining (together with other properties of the implanted device) the bio(non)compatibility of the implant. Such amplification of terminology which establishes differences between biocompatibility as a generalized characteristic of biomaterials in all their interrelations with the host's organism and the influences on local processes around implants, makes the …

A Microstructural Investigation Of Calcium Hydroxyapatites Synthesized From Cahpo4•2h2o And Ca4(Po4)2o, Kevor S. Tenhuisen, Boyd A. Clark, Maria Klimkiewicz, Paul W. Brown

Cells and Materials

This investigation determined the effects of reaction temperature and bulk composition on the microstructural features of hydroxyapatites (HAp) synthesized from reaction between particulate CaHPO₄·2H₂O and Ca₄(PO₄)₂O. These data were used in combination with previous work to further elucidate the mechanistic reaction path taken by these calcium phosphate cements. HAps having two different compositions (Ca/P = 1.50 and 1.67) were synthesized between 15.0 and 70.0°C. All reactions reached completion as indicated by X-ray diffraction. Single point nitrogen absorption was performed on all samples to determine specific surface areas. The HAp which …

Time Course Of Recruitment, Pit Formation And Apoptosis Of Osteoclast Populations On Dentin In Vitro, Jihyun Kang, Rigoberto Cornejo, Kevin J. Hirokawa, Susan M. Digiorgio, Darlene F. Howard, Susan F. Silverton

Cells and Materials

The resorptive capacity of osteoclasts in vitro has been used as an indicator of bone resorption. However, the kinetics of osteoclast development and senescence is not well understood. It has been noted that mononuclear precursors migrate to calcified substrate and after multi-nucleation become competent bone resorbing cells. Osteoclasts, once finished a wave of resorption, become senescent. In order to determine the survival characteristics of osteoclast populations involved in calcified tissue destruction, we have investigated the time course of the recruitment to dentin and apoptosis of osteoclasts. We have established the linkage between these measurements and the time course of the …

Biodegradation Of A Nano-Hydroxyapatite/Collagen Composite By Peritoneal Monocyte-Macrophages, F. Z. Cui, C. Du, X. W. Su, X. D. Zhu, N. M. Zhao

Cells and Materials

A nano-hydroxyapatite/collagen composite was prepared by precipitation of hydroxyapatite from an aqueous solution onto collagen. Mouse peritoneal macrophages were used to investigate the in vitro biodegradation of the composite. The results showed the mechanism of phagocytosis and extracellular degradation process. The cells that belong to the mononuclear phagocyte system showed some morphological characteristics similar to those of osteoclasts and made pits on the composite surface. The local modification of the material surface by the cell was another phenomenon distinguishable from the degradation process. The degradation and modification made the material porous with a widely varying Ca/P ratio.

The Role Of Surface Characteristics In The Initial Adhesion Of Human Bone-Derived Cells On Ceramics, H. Zreiqat, O. C. Standard, T. Gengenbach, J. G. Steele, C. R. Howlett

Cells and Materials

The tissue/biomaterial interactions of three biomaterials of potential use in bone implants were studied in vitro. The mechanism of cell adherence to various ceramic substrata has been investigated by measurement of short term (90 minutes) cell attachment and spreading rate. We have determined the effect of two serum glycoproteins, fibronectin and vitronectin, on the adhesion of human bone derived cells (HBD-cells) cultured on three different types of ceramics {alumina (Al₂O₃), hydroxyapatite (HAP) and yttria-doped tetragonal zirconia polycrystal (Y-TZP)} . The attachment of HBD-cells to alumina and hydroxyapatite was approximately 60% of that to Y-TZP. Furthermore, …

The Influence Of A Fibrin-Coating Inside A Biodegradable Poly(Dl-Lactide-Ε-Caprolactone) Nerve Guide On Peripheral Nerve Regeneration, W. F. A. Den Dunnen, J. M. Schakenraad, B. Van Der Lei, A. J. Pennings, P. H. Robinson

Cells and Materials

The aim of this study was to evaluate the effect of a fibrin-coating on the inner surface of a biodegradable poly(DL-lactide-E-caprolactone) nerve guide on the speed and quality of the nerve regeneration. The nerve regeneration and orientation of the nerve fibers, as well as the fibrous tissue formation were evaluated. On the short term, nerve regeneration was slightly faster in the non-coated nerve guide. After longer implantation periods (≥ 4 weeks), nerve regeneration in the fibrin-coated nerve guides was characterized by a severe inflammatory response with large numbers of macrophages and polymorphonuclear cells (PMN's). This study clearly demonstrates that nerve …

Heterogeneity Of Natural Biofilm Communities, J. R. Lawrence, D. R. Korber, G. M. Wolfaardt

Cells and Materials

Scanning confocal laser microscopy (SCLM) studies have shown that microbial biofilms consist of a spatially heterogeneous arrangement of bacterial cells, biogenic extracellular material, and void space. Biofilm architecture is dominated by the presence of cell aggregates interspersed by channels, the arrangement of which varies for different hydrodynamic regimes, ages, species composition, or nutrient status. This organization may regulate the flux of nutrients and oxygen, creating chemical microenvironments (Eh, pH) facilitating the growth of aerobic heterotrophs and anaerobes. The presence of microenvironments has been confirmed using laser microscopy and environmentally sensitive fluorescent probes. In addition, changes in cell number and growth …

Collagen Fibres Are Not Required For Initial Matrix Mineralization By Bone Cells, M. M. Hosseini, S. A. F. Peel, J. E. Davies

Cells and Materials

Passaged primary cultures of young adult rat bone marrow cells were maintained in medium containing combinations of the supplements dexamethasone, ascorbic acid and Na-ß-glycerophosphate. The cultures were examined by both light and scanning electron microscopy (with additional energy dispersive X-ray analysis). In cultures with fully supplemented medium, an extracellular matrix formed at the culture dish surface, beneath developing bone nodules; this matrix was mineralized but collagen-fibre free and corresponded to that which we have reported previously as the equivalent of the cement line in vivo. In selected samples this interfacial, cement line, matrix was analyzed by X-ray …

Physical And Biological Evaluation Of Hydroxylapatite Films Formed On Ti6a14v Substrates By Excimer Laser Ablation, Tatjana Dostálová, Miroslav Jelínek, Lucie Himmlová, Vlasta Pesáková, Milan Adam

Cells and Materials

Thin films of hydroxylapatite, about 500 nm, were formed on Ti6Al4V by excimer laser ablation. Ten different deposition conditions were used such as deposition atmosphere (vacuum, pure water vapor, mixture of Ar and water vapor), substrate temperature, target-substrate distance and energy density. Mechanical and physical analyses were carried out by Rutherford backscattering and particle induced X-ray emission; crystallinity of films was determined by X-ray diffraction, surface topography by scanning electron microscopy and adhesion by a scratch test. Biological evaluation of samples was also performed. The fibroblast proliferation test was used, morphological evaluation of macrophages was carried out, and the activity …