Thin films of tin oxide (SnO2) with the rutile structure are the subject of many investigations due to their potential applications, such as gas sensing devices, lithium batteries cathodes and solar cells. There is a growing interest in the development of gas sensors using SnO2 thin films due to their high surface to volume ratio. Previous studies have shown that the gas sensing properties of SnO2 are very dependent on the microstructure and that doping elements can greatly influence their electrical properties. In this paper we present transmission electron microscopy (TEM) studies of the microstructure and crystal defects of SnO2 thin films.

Tin oxide films 5 nm in thickness were deposited on the surface of sapphire (A12O3) by pulsed laser ablation of ceramic SnO2 targets. The film microstructure was studied using X ray diffraction, atomic force microscopy and transmission electron microscopy. Defects were studied using high resolution transmission electron microscopy (HRTEM).

Continuous increase in recording densities of the Co-based longitudinal media requires a drastic scaling down of the grain size in order to keep the required signal to noise ratio. However, this approach to increase the areal density will collapse when the grain size reaches the superparamagnetic limit. As an alternative, based on the analysis of the demagnetization mechanisms, Iwasaki and Takemura suggested the possibility of perpendicular magnetic recording (PMR), and computer simulation, predict areal densities of more than 300Gbit/in for this configuration. The c-axis oriented Co-based hep alloys with the magnetocrystaline anisotropy larger than the demagnetizing energy, are good candidates for the PMR media. However, before this type of materials can be realized, the magnetic domain structure must be well characterized. In this paper detailed analyses of the characteristics and shape of the magnetic domains present in the c-axis oriented CoCr films with thickness relevant for the recording industry are discussed.

Hard drives in portable computers require media deposited on glass substrates and employ NiAl as the first seed layer to optimize magnetic performance. From observations of a 112 XRD peak [1], a <112> texture has been reported to develop as sputtered films of NiAl thicken; however, synchrotron analysis observes additional cubic peaks [2]. The electron diffraction in this study detects no dominant <112> orientation in NiAl, but rather that the NiAl films (and subsequent cubic underlayers) are closer to 3-D isotropic. Furthermore, the +/-20° range of ﹛1100﹜ orientations observed [3] in the Co media grains grown on NiAl/Cr occurs not because of one (or two) special zone axis relationship(s), nor due to substrate surface finish, but rather as a consequence of multiplicity relationships between the cubic and hexagonal crystals. Although an “increase” in variants is often accepted for an upper film (e.g. bicrystals of [1120] Co on [200] Cr),

Austenitic stainless steels plasma-nitrided at low temperature can have a tremendously improved surface hardness without affecting their excellent corrosion resistance. The surface layer of these nitrided materials was considered to be composed of an uncharacterized, so called “S-phase”. During the past decade, several research groups have studied “S” phase using X-ray diffraction and transmission electron microscopy (TEM), but its microstructure is not yet well understood and is still a topic of debate. In this paper, we characterize the microstructure of 316 stainless steel nitrided by intensified plasma-assisted processing (IPAP) using cross-sectional TEM.

Samples of 316 austenitic stainless steel were nitrided for 1 hour by IPAP at a temperature of ∼ 400 °C. Plasma-nitrided samples were cross-sectioned and glued face-to-face by joining the nitrided surface. Crosssectional specimens for TEM observations were prepared by mechanical grinding, polishing and dimpling followed by Ar+ milling. TEM studies were carried out in a newly installed JEOL JEM 2010 electron microscope in the Materials Characterization Facility at the Louisiana State University.

The Crystallization of amorphous silicon (α-Si:H) at lower temperatures is a challenging area of research these days because it will open up the possibilities of fabricating semiconductor devices like thin film transistors (TFT's), solar cells, active matrix liquid crystal display (AMLCD) devices at considearbly lower cost. Various metals e.g. Ni, Cu, Au, Ag and Al have been used to bring down the crystallization temperature of α-Si. We have found that aluminum assisted crystallization can bring down the temperatures of crystallization to as low as 200 °C. The crystallization behavior of α- Si:H has been studied by scanning electron microscopy, Raman spectroscopy, XPS spectroscopy and X-Ray diffraction but very little work has been carried out on microstructural investigation of the material using transmission electron microscopy. We have prepared specimen for die TEM study of α-Si:H and that of crystallized Si obtained by aluminum assisted crystallization. A detailed investigation of the crystallization behavior of α-Si:H using TEM have been carried out.

CdTe/CdS thin film solar cells are being investigated extensively these days by many workers as an option for low cost photovoltaic applications . In order to achieve high efficiency solar cell it is important that the CdS film should have minimum possible structural defects and reasonably large grain size. The CdS films for CdTe/ CdS solar cell structure are mostly grown on glass substrates by chemical bath deposition (CBD). Although adherent, transparent and conformal films with index of refraction close to single crystal CdS can be grown by CBD, impurity inclusions and micropinholes are a problem there in. Very little work has been carried out to grow CdS films by thermal evaporation in vacuum. In the present work we have grown pure and CdCl2 doped CdS films on glass substrates by thermal evaporation and carried out microstructural investigations of these films using scanning electron microscopy.

Corning 7059 glass of 25.4 x 25.4 x 1.2 mm size were used as substrates for the deposition of CdS as well as CdCl2 doped CdS films.

Optical fibers have been extensively employed in a variety of fields. However, the need of high strength, excellent resistance to moisture permeation and tolerance to heat becomes apparent when such optical fibers are used in nuclear power plants and chemical plants in particular. Plastic coatings as conventional made of optical fibers cables would be replaced by the optical fiber coated with a layer of metal.

Several techniques have been applied to make a metal coating for the optical fibers. Dipping method, to pass optical fibers through a bath containing metal melt, was found the simplest. This dipping method, however, suffers from a disadvantage of a generation of a microbent due to the differences of the linear expansion between metal and the silica substrate [1]. Moreover, the control of the thickness was found difficult using the dipping method. Chemical vapor deposition was also used to form the metal coating on optical fibers.

Lead zirconate titanate (PbZrxTil-xO3, PZT) is one of the important ferroelectric materials for the storage elements of high-speed non-volatile memories. It also has much potential to be used in pyroelectric sensor, ultrasonic motor, and multiplayer ceramic capacitor.

PZT (Zr/Ti = 48/52) thin films were prepared using a metal-organic decomposition (MOD) process. The precursor solution used for PZT thin film preparation was based on lead acetate trihydrate, Pb(CH3COO)2; zirconium nitrate, Zr(NO3)4.5H2O; and titanium nbutoxide, Ti(nC2H9)4. 2-butoxyethanol was chosen as a solvent. A 30% excess Pb was added to the precursor to compensate for the loss of lead oxide during the annealing process. Acetic acid was used as a complexing agent for PZT solution to control the hydrolysis and condensation rates. The 0.3M precursor solution was spin-coated on the Pt(111)/Ti/SiO2/Si substrates for 20s at 3000 rpm. The deposited film was fired at 450 °C for 10 min and repeated five times to burn out the organics. The films were crystallized at 600 °C in air for 1 hr.

The I-III-VI (I= Cu, III= In and VI= Se) ternary chalcopyrite semiconductors are promising materials for the fabrication of thin film solar cells. The device properties of these polycrystalline CuInSe2-based solar cells are critically influenced by their structural features (i.e. grain sizes, uniformity and defect chemistry) and therefore require careful optimization. The structural features of the films were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The results from this fundamental study were used to compare and evaluate the respective thin film growth methods in terms of producing device quality material for solar cell application.

In order to investigate the influence of the structural properties on device performance, samples were prepared by various growth techniques. The composition (Cu/In atomic ratio) of the films as well as the growth conditions were varied in order to obtain optimum material properties. All films were deposited on Mo-coated glass substrates and the typical layer thickness were around 2μm.

Pb(Mg1/3Nb2/3)O3 (PMN)- and its solid solution with PbTiO3 (PT) is one of the lead-based relaxor ferroelectrics and has been the most widely studied materials because of their high dielectric constants and high electrostrictive coefficients. The potential impact of the thin film ferroelectric relaxors in the integrated actuators and sensing applications has stimulated research on the growth and characterization of thin films. Thin films have been made by pulsed-laser deposition (PLD), sol-gel and metalrganic chemical-vapor deposition. It is known that electrical properties may be strongly influenced by the microstructure of films and the interface structures between different phase in such heterostructure systems. In this paper, we report the investigation of interfacial mismatch and interface structure of epitaxial Pb(Mg1/3Nb2/3)O3 (90%)- PbTiO3 (10%) relaxor thin film by high resolution transmission electron microscopy (HRTEM).

Thin film capacitors of Pb(Mg1/3Nb2/3)O3 (90%) - PbTiO3 (10%) (PMN-PT) were grown by PLD on (100)-oriented LaA1O3 (LAO) substrates. La0.5Sr0.5CoO3 (LSCO) layer was deposited as electrode. Cross-sectional transmission electron microscopy samples were prepared following the traditional procedures including cutting, gluing, polishing and ion milling.

In situ dynamic experiments in the TEM provide a powerful and unique method of investigating materials, when they are subjected to different environments or treatments. Study of plastic deformation mechanisms of free standing thin metallic films have evoked strong research interest in recent years. In the past, free standing thin metallic films have been tested in tension, where the tensile properties were measured and compared with those of bulk samples. Certain other studies dealt with metallic films attached to the substrate, where the deformation was introduced by thermal cycling or mechanical straining. The deformaion of bulk nanocrystalline samples has also been extensively studied recently. However, few publications have documented in situ straining of free standing metallic films with ultrafine grain size. In this study, an in situ straining stage was employed in the TEM to deform a free standing thin nickel film with grain sizes in submicron and nanocrystalline range, and the goal was to observe the microstructural response to deformation.

Microwave processing has progressed into a promising procedure for use in the clinical electron microscopy laboratory. In striving for faster turn-around-time in the clinical patient environment, the laboratory microwave has become a very exciting tool. The development of microwave technology enhances the pathologists’ ability to diagnose quickly without compromising quality.

This laboratory's patient sample base is primarily renal biopsies. Tumors and other tissue abnormalities are also diagnosed. Animal and human renal tissue were used for experimentation with the microwave processing protocol. With the need for consistency between the existing resin of choice and standard processing protocol, procedures were developed with these criteria in mind. The standard electron microscopy processing protocol for this laboratory is fixation in either 10% neutral buffered formalin (NBF) or 4% buffered gluteraldehyde followed by post-fixation with 1% osmium tetroxide for 1 hour. The dehydration is performed with gradients of 50% to 100% ethanol followed by a transition solvent of propylene oxide into resin infiltration and polymerization.

Abstract

Recently, specimen processing using microwave irradiation was described as a potential tool to enhance a variety of procedures used in microscopy including fixations, embedding, antigen retrieval (AGR) and immunolabeling (1,2,3). A comparison of conventional staining and staining after microwave irradiation was performed for several fluorescent vital nuclear stains, Performing the labeling reaction under controlled microwave irradiation results in significant improvements in the labeling of nuclei, such as shortening the times of incubation and allowing the detection of otherwise inaccessible sites. In addition to investigate the basis of the enhancement, we have labeled intact samples such as living onion root meristems and Drosophila embryos. In both systems, vital fluorescent nuclear stains were applied to the specimen on a glass slide and was microwave irradiated using a variable wattage microwave (model 3451 Ted Pella, Inc.). This resulted in clear fluorescent labeling of the nuclei. This result has not been previously reported in the absence of microwave treatment, other than by microinjection.

The actin cytoskeleton is involved in various cellular functions including cell shape determination, organelle transport, and cell polarity establishment. In order to study the function and dynamics of actin in plant cells, methods to image its orientation have to be optimized. Although, green fluorescent proteins (GFP) from the jellyfish Aequoria victoria have been used for visualizing actin filaments in plant cells, the technique is still in its infancy and has some limitations. Actin in plant cells is difficult to preserve and hence visualize mainly because of the problems associated with specimen fixation and processing. This is particularly true for bulky specimens such as plant organs because of the additional requirement for embedding and sectioning after the tissues are fixed and dehydrated. In order to overcome these difficulties, we have modified a method previously used for onion epidermal cells and suspension cells, and applied this to fresh Vibratome sectioned root tissues.

Ribulose bisphosphate carboxylase/oxygenase (Rubisco), an abundant enzyme in chloroplasts, must be activated by CO2 in order for it to catalyze the carboxylation of ribulose bisphosphate. Rubisco activase, a nuclear encoded chloroplast protein was first identified as a biochemical lesion in the rca mutant of Arabidopsis (1) which lacked this enzyme. Study of Rubisco in this mutant (2) and transgenic tobacco plants with reduced Rubisco activase levels showed that Rubisco could not achieve and maintain an adequate level of activity, in vivo, without an activase. Rubisco activase promotes ‘activation’ of Rubisco by overcoming the deleterious effects of tight binding sugar phosphates and low chloroplast CO2 levels on catalysis and carbamylation (1).

Rubisco activase has been detected in higher plants (3), in unicellular green algae (4,5) and in cyanobacteria (6). Though the presence of Rubisco in guard cell chlroplasts was a subject of controversy, several immunolight and immunoelectron microscopic studies have demonstrated the presence of Rubisco in guard cells (7).

Liquid-based technology is becoming more widely used in cytology laboratories for gynecologic and non-gynecologic specimens. Like many other institutions we recently incorporated the liquid-based technology into our laboratory. We have an electron microscope facility in our department and utilize the TEM for ukrastructural evaluation of cytology specimens when additional information is needed. This study compares the preservation of cells from cytology specimens when prepared by routine methods and when placed in the preservative fluid for liquid-based preparations.

Routine smears were made from fine needle aspirations at the time of the procedure or from urine or body fluids on receipt. Some material from three of the non-gynecologic specimens was placed in CytoRich Red (TriPath Imaging, Burlington, NC) fluid. The specimens in CytoRich Red were then centrifuged, and the pellets were placed in 3% glutaraldehyde in cacodylate buffer. Eight body fluid or fine needle aspiration specimens in Plasma-Lyte (Baxter Healthcare Corp., Deerfield, IL) balanced electrolyte solution were centrifuged, and the pellets were placed in 3% glutaraldehyde in cacodylate buffer.

Microscopic evaluation of urine sediment by the cytology laboratory can provide valuable information to the clinician. While some crystal types are considered normal, others are abnormal and indicate disease. Traditional analysis within the cytology laboratory includes direct cytospin preparations and smears of the urine sample. Light microscopy with polarized light is then utilized to examine the slide preparations.

Many cytology laboratories have recently incorporated liquid-based technology for gynecologic and non-gynecologic specimen preparation. Specimens placed in the proprietary fluid are processed according to the manufacturer's directions with the ultimate result of a thin, circular layer of cells on the slide. The advantages of liquidbased methods include concentration of the cells into a thin layer, localization to a small area of the slide, minimization of background debris, and ability to make additional specimens from the same sample. When the liquid-based slide preparations of urine made in our lab were compared to the conventional cytospin smears,

Negative staining is very useful, but typically produces a resolution level of 20-25A and thus reveals only the quaternary level of protein structure. The recent finding that heavy metals are not required to obtain sufficient contrast for direct TEM imaging has led to examinations of various light atom compounds in a search for new unconventional staining agents having improved properties that can lead to higher resolution. This report examines whether the acetate salt of a divalent cation, magnesium, can function successfully for experimental negative staining.

Magnesium acetate (Mg(C2H3O2)2˙4H2O) (F.W. = 214.5) was used as an aqueous solution at 200mM. Bovine liver catalase crystals were examined as test specimens under standardized conditions. Suspended crystals were deposited onto a hydrophilic thin carbon supporting film and then were negatively stained by the on-grid procedure described previously. Imaging at l00kV used a JEOL 100-CX transmission electron microscope with Kodak S0-163 film.

Histochemical methods offer an excellent research tool for the characterization of glycoproteins in the secretory cells, thus contributing to the elucidation of the pathophysiology of different diseases. The different staining characteristics of mucins can be useful in diagnostic histopathology. It has been proposed that the reduction in sulphated glycoproteins and an increase in sialomucins in intestinal mucosa was an indicator of premalignant changes in carcinoma of the bowel. It has subsequently argued that this change may be consequence rather than a precursor of neoplasia. It may still be of some value as a marker of a premalignant change although it is somewhat variable. Previous studies have demonstrated the characterization of glycoproteins in different type of epitheloid cells in normal and pathologic conditions by using histochemical and electron microscopic techniques. However; little information has been available concerning the exact features of secretory granules in both normal and tumoral cells in lung.

The high concentration of low-density lipoprotein in the plasma is the major risk factor of atherosclerosis. On the other hand, another plasma lipoprotein—high-density lipoprotein (HDL) — is inversely correlated with atherosclerosis. Recent studies have demonstrated that HDL mediates the transport of cholesterol from peripheral tissues to the liver through “reverse cholesterol transport” pathway. However there is considerable debate about the mechanisms by which HDL removes excess cholesterol from cells. Two different pathways were suggested: (i) a docking receptor promoting cholesterol translocation, or (ii) a receptor mediated intracellular endosomal pathway termed “retroendocytosis”. In the present study, we performed fluorescence and electron microscopy to visualize the uptake of HDL using cholesterol-load rat aortic endothelial and smooth muscle cells in vitro.

Endothelial and smooth muscle cells were obtained from rat aorta and cultured in medium under 5% CO2/ 95% air atmosphere. Then confluent monolayers of endothelial and smooth muscle cells were incubated in cholesterol or fluorescence-labeled cholesterol DMEM medium for 48 hr.