Electrode Property of Sintered Ceramic Based on CaMnO3 in LiOH Aqueous Solution

The freeze etching technique is potentially useful for examining dilute solutions or suspensions of macromolecular materials. Quick freezing of aqueous solutions in Freon or propane at or near liquid nitrogen temperature produces relatively large ice crystals and these crystals may damage the structures to be examined. Cryoprotective agents may reduce damage to the specimem, hut their use often results in the formation of a different set of specimem artifacts.In a study of the structure of polyethylene oxide gels glycerol and sucrose were used as cryoprotective agents. The experiments reported here show some of the structures which can appear when these cryoprotective agents are used.Figure 1 shows a fractured surface of a frozen 25% aqueous solution of sucrose. The branches of dendritic ice crystals surrounded hy ice-sucrose eutectic can be seen. When this fractured surface is etched the ice in the dendrites sublimes giving the type of structure shown in Figure 2. The ice-sucrose eutectic etches much more slowly. It is the smooth continuous structural constituent surrounding the branches of the dendrites.

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Effects of compression during formation on the microstructure of composite hydroxylapatite/plaster implants for bone reconstruction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105813 ◽

1988 ◽

Vol 46 ◽

pp. 750-751

Author(s):

J. Hanker ◽

K. Cowden ◽

R. Noecker ◽

P. Yates ◽

N. Georgiade ◽

...

Keyword(s):

Cosmetic Surgery ◽

Glass Plate ◽

Surgical Reconstruction ◽

Equal Weight ◽

Sintered Ceramic ◽

Setting Times ◽

Excess Water ◽

Mixture Prior ◽

Mechanical Strengths ◽

Calcium Sulfate Hemihydrate

Composites of plaster of Paris (PP) and hydroxylapatite (HA) particles are being applied for the surgical reconstruction of craniofacial bone defects and for cosmetic surgery. Two types of HA particles are being employed, the dense sintered ceramic (DHA) and the porous, coralline hydroxylapatite (PHA) particles. Excess water is expressed out of the moistened HA/PP mixture prior to implantation and setting by pressing it in a non-tapered syringe against a glass plate. This results in implants with faster setting times and greater mechanical strengths. It was therefore of interest to compare samples of the compressed versus noncompressed mixtures to see whether or not any changes in their microstructure after setting could be related to these different properties.USG Medical Grade Calcium Sulfate Hemihydrate (which has the lowest mortar consistency of any known plaster) was mixed with an equal weight of Interpore 200 particles (a commercial form of PHA). After moistening with a minimum amount of water, disc-shaped noncompressed samples were made by filling small holes (0.339 in. diameter x 0.053 in. deep) in polypropylene molds with a microspatula.

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Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010679x ◽

1988 ◽

Vol 46 ◽

pp. 946-947

Author(s):

A. Legrouri

Keyword(s):

Aqueous Solution ◽

Thermal Decomposition ◽

Physicochemical Properties ◽

Surface Area ◽

Vanadium Pentoxide ◽

High Purity ◽

Gas Adsorption ◽

Rhodium Catalyst ◽

Optical Methods ◽

Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

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Scanning electron microscopy of composite hydroxylapatite/plaster implants for bone reconstruction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143250 ◽

1986 ◽

Vol 44 ◽

pp. 326-327

Author(s):

J. S. Hanker ◽

B. L. Giammara

Keyword(s):

Tooth Extraction ◽

Alveolar Ridge ◽

Small Particles ◽

Alveolar Ridge Augmentation ◽

Sintered Ceramic ◽

Ridge Augmentation ◽

Fibrovascular Tissue ◽

Infrabony Defects ◽

Edentulous Patients ◽

Scanning Electron

Nonresorbable sintered ceramic hydroxylapatite (HA) is widely employed for filling defects in jaw bone. The small particles used for alveolar ridge augmentation in edentulous patients or for infrabony defects due to periodontal disease tend to scatter when implanted using water or saline as the vehicle. Larger blocks of this material used for filling sockets after tooth extraction don't fit well. Studies in our laboratory where we compared bovine serum albumin, collagen and plaster of Paris as binders to prevent particle scatter during implantation suggested that plaster was most useful for this purpose. In addition to preventing scatter of the particles, plaster enables the formation of implants of any size and.shape either prior to or during surgery. Studies with the PATS reaction have indicated that plaster acts as a scaffold for the incorporation of HA particles into bone in areas where the implant contacts either host bone or periosteum. The shape and integrity of the implant is maintained by the plaster component until it is replaced over a period of days by fibrovascular tissue.

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Characterization of microwave-sintered ceramic composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151519 ◽

1993 ◽

Vol 51 ◽

pp. 1136-1137

Author(s):

X. Zhang ◽

Y. Pan ◽

T.T. Meek

Keyword(s):

Matrix Material ◽

Maximum Output Power ◽

Ceramic Matrix Composite ◽

Ceramic Composites ◽

Processing Technique ◽

Structure Characterization ◽

Alumina Powder ◽

Maximum Output ◽

Sintered Ceramic

Industrial microwave heating technology has emerged as a new ceramic processing technique. The unique advantages of fast sintering, high density, and improved materials properties makes it superior in certain respects to other processing methods. This work presents the structure characterization of a microwave sintered ceramic matrix composite.Commercial α-alumina powder A-16 (Alcoa) is chosen as the matrix material, β-silicon carbide whiskers (Third Millennium Technologies, Inc.) are used as the reinforcing element. The green samples consisted of 90 vol% Al2O3 powder and 10 vol% ultrasonically-dispersed SiC whiskers. The powder mixture is blended together, and then uniaxially pressed into a cylindrical pellet under a pressure of 230 MPa, which yields a 52% green density. The sintering experiments are carried out using an industry microwave system (Gober, Model S6F) which generates microwave radiation at 2.45 GHz with a maximum output power of 6 kW. The composites are sintered at two different temperatures (1550°C and 1650°C) with various isothermal processing time intervals ranging from 10 to 20 min.

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TEM observation of iron oxide pillars in montmorillonite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177544 ◽

1990 ◽

Vol 48 (4) ◽

pp. 882-883

Author(s):

H. Mori ◽

Y. Murata ◽

H. Yoneyama ◽

H. Fujita

Keyword(s):

Aqueous Solution ◽

Iron Oxide ◽

Fine Particles ◽

Aqueous Suspension ◽

Volume Ratio ◽

Exchange Capacity ◽

Nano Composites ◽

Pillared Montmorillonite ◽

Topographic Features ◽

Transmission Electron

Recently, a new sort of nano-composites has been prepared by incorporating such fine particles as metal oxide microcrystallites and organic polymers into the interlayer space of montmorillonite. Owing to their extremely large specific surface area, the nano-composites are finding wide application[1∼3]. However, the topographic features of the microstructures have not been elucidated as yet In the present work, the microstructures of iron oxide-pillared montmorillonite have been investigated by high-resolution transmission electron microscopy.Iron oxide-pillared montmorillonite was prepared through the procedure essentially the same as that reported by Yamanaka et al. Firstly, 0.125 M aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate, [Fe3(OCOCH3)7 OH.2H2O]NO3, was prepared and then the solution was mixed with an aqueous suspension of 1 wt% clay by continuously stirring at 308 K. The final volume ratio of the latter aqueous solution to the former was 0.4. The clay used was sodium montmorillonite (Kunimine Industrial Co.), having a cation exchange capacity of 100 mequiv/100g. The montmorillonite in the mixed suspension was then centrifuged, followed by washing with deionized water. The washed samples were spread on glass plates, air dried, and then annealed at 673 K for 72 ks in air. The resultant film products were approximately 20 μm in thickness and brown in color.

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The microstructure of functionalized poLyacrylonitrile beads for bioseparations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178604 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1094-1095

Author(s):

Eduardo A. Kamenetzky ◽

David A. Ley

Keyword(s):

Aqueous Solution ◽

Affinity Chromatography ◽

Pore Size Distribution ◽

Pore Size ◽

Surface Coverage ◽

Vacuum Impregnation ◽

Thin Sections ◽

Selective Staining ◽

Low Viscosity ◽

Diamond Knife

The microstructure of polyacrylonitrile (PAN) beads for affinity chromatography bioseparations was studied by TEM of stained ultramicrotomed thin-sections. Microstructural aspects such as overall pore size distribution, the distribution of pores within the beads, and surface coverage of functionalized beads affect performance properties. Stereological methods are used to quantify the internal structure of these chromatographic supports. Details of the process for making the PAN beads are given elsewhere. TEM specimens were obtained by vacuum impregnation with a low-viscosity epoxy and sectioning with a diamond knife. The beads can be observed unstained. However, different surface functionalities can be made evident by selective staining. Amide surface coverage was studied by staining in vapor of a 0.5.% RuO4 aqueous solution for 1 h. RuO4 does not stain PAN but stains, amongst many others, polymers containing an amide moiety.

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