Aluminum Oxide Ceramics Obtained by Commercial Starch Consolidation with Gradient Porosity

2010 ◽  
Vol 63 ◽  
pp. 175-180
Author(s):  
Rogério Pinto Mota ◽  
Rodrigo Sampaio Fernandes ◽  
Élson de Campos ◽  
Emerson Ferreira de Lucena ◽  
Mauricio A. Algatti
Keyword(s):  
Present Method ◽  
Mass Concentration ◽  
Light And Electron Microscopy ◽  
Porous Ceramics ◽  
Oxide Ceramics ◽  
Water Drainage ◽  
Density Measurements ◽  
The Common ◽  
Starch Consolidation ◽  
Gelling Process

The starch consolidation technique is commonly used for obtaining porous ceramics due to bonding and porous-maker starch characteristic during gelling process. The method adopted here improved the water drainage by using a plaster porous base (70 and 90 consistency values) improving the water drainage by action of gravity and the capillary effect. It used slip with 50 vol% solids and as precursors oxide A-1000SG and commercial cornstarch with a mass concentration varying from 10 to 40%. For comparison between the present method and the common one, slip was put in impermeable and permeable base moulds. The gelling occurred at 70°C for 2 hours and the drying at 110°C. Pre-sintering was carried out at 1000°C and the sintering at 1600°C with a plateau of 1 hour. Results showed that the plaster consistency of the mould bases was preponderant on ceramics porosity. Porosity and apparent density measurements using light and electron microscopy revealed variation of 5% of porosity from the top to the bottom of the samples.

Porous Ceramics Obtained by Slip/Starch Casting Consolidation Method (SSCC)

2016 ◽  
Vol 881 ◽  
pp. 52-57
Author(s):  
Rodrigo Sampaio Fernandes ◽  
Elson de Campos ◽  
Jerusa Góes Aragão Santana ◽  
Rogério Pinto Mota
Keyword(s):  
Slip Casting ◽  
Porous Ceramics ◽  
Mechanical Resistance ◽  
Alumina Ceramics ◽  
Forming Process ◽  
Porous Mold ◽  
Different Characteristics ◽  
Starch Consolidation ◽  
Resistance Value ◽  
Gelling Process

Slip/starch casting consolidation (SSCC) is a technique for obtaining porous ceramics, which joins the forming process by starch consolidation with the slip casting method. In this work, a slip which contains ceramic powders, starch and dispersant, is poured into a porous mold and is taken to an oven so that the gelling process occurs. After sintering, it is noticed that the ceramics show different characteristics from the ones obtained exclusively by slip casting or by starch consolidation. Alumina ceramics were produced by using the three methods presented in this work. The ceramics were characterized by apparent porosity, mechanical resistance and scanning electron microscopy. The ceramics produced by SSCC presented the highest mechanical resistance value (289 MPa), while the ones produced by starch consolidation and slip casting presented values of 126 MPa and 191 MPa, respectively.

Effect of Different Solid Amounts in the Physical and Microscopical Properties of SiC Porous Ceramics

2008 ◽  
Vol 591-593 ◽  
pp. 685-690 ◽  
Author(s):  
Jerusa Góes Aragão Santana ◽  
José Luiz Minatti ◽  
Élson de Campos ◽  
Francisco Cristóvão Lourenço de Melo ◽  
Tetunori Kajita
Keyword(s):  
Organic Material ◽  
Thermal Stresses ◽  
Ceramic Powder ◽  
Porous Ceramics ◽  
Forming Process ◽  
Solid Load ◽  
Starch Consolidation ◽  
Sintering Processes ◽  
Roughness Measurements

The presence of pores in ceramics is directly related to the chosen forming process. So, in the starch consolidation method, the ceramics show, after burning, pores with morphology similar to that presented by this organic material. On the other hand, the increase in solid load leads up to alterations in dispersion viscosity, increasing the thermal stresses during drying and sintering processes. In order to verify the solid percentage influence in ceramic final properties, samples were prepared with silicon carbide in different compositions using or not starch as binder agent and pore forming element. The characterization of the ceramic pieces was performed by superficial roughness measurements, porosity besides by optical and scanning electron microscopy. The results showed ceramics with SiC and starch presented physical and microscopic properties slightly higher in relation to those with only ceramic powder in their composition. The presence of organic material, agglomerated and foam during the forming were essential for the final properties of the studied samples.

Hydroxyamidines as New Extracting Reagents for Spectrophotometric Determination of Cadmium with 4-(2-Pyridylazo)naphthol in Industrial Effluents, Coal, and Fly Ash

1993 ◽  
Vol 76 (3) ◽  
pp. 604-608 ◽  
Author(s):  
Sumon Chakravarty ◽  
Manas Kanti Deb ◽  
Rajendra Kumar Mishra
Keyword(s):  
Spectrophotometric Determination ◽  
Environmental Samples ◽  
Present Method ◽  
Industrial Effluents ◽  
Molar Absorptivity ◽  
Binary Complex ◽  
Matrix Interference ◽  
Relative Standard ◽  
The Common

Abstract A simple, sensitive, and selective extractive spectrophotometric method for the determination of cadmium in trace quantities with N1-hydroxy-N1,N2- diphenylbenzamidine (HDPBA) and 4-(2-pyridylazo) naphthol (PAN) is described. The method is based on the extraction of cadmium with HDPBA into chloroform at pH 9.0 ± 0.2 and simultaneous spectrophotometric determination wiith PAN. The binary Cd(ll)-HDPBA complex extracted into chloroform has a molar absorptivity of 1.96 x 104L/ mol/cm at λmax 400 nm. The sensitivity of the yellow Cd(ll)-HDPBA complex was increased remarkably by the addition of PAN to the binary complex. With 6 different hydroxyamidines tested, the red-orange complex in chloroform exhibited maximum absorbance at 530-550 nm, with molar absorptivity values of 3.2-5.6 x 104L/mol/cm. The method adheres to Beer’s law up to 1.5 μg cadmium/mL organic phase. The detection limit of the method is 0.02 μg Cd/mL. Investigations of the effect of foreign ions revealed that the present method is free from matrix interference of most of the common ions (e.g., Fe(lll), Ni(ll), Cu(ll), Mn(ll), V(V), Co(ll), Al(lll), Cu(ll), Mg(ll), and Mo(VI)). The relative standard deviation for 10 repetitive analyses of the metal was 1.4%. The validity of the method was tested successfully with various environmental samples.

The Fine Structure of Brunner’s Glands in the Human

1967 ◽  
Vol 25 ◽  
pp. 66-67
Author(s):  
T. S. Lesson ◽  
C. R. Leeson
Keyword(s):  
Light And Electron Microscopy ◽  
Histological Structure ◽  
Surgical Biopsy ◽  
Brunner's Glands ◽  
Biopsy Specimens ◽  
Brunner’S Glands ◽  
Submucosal Glands ◽  
History Of ◽  
The Common ◽  
Foamy Cytoplasm

Duodenal submucosal glands occur in all mammals but show species differences both in their extent and histological structure. Surgical biopsy specimens were obtained from five individuals aged from 37 to 56 with no history of duodenal abnormality. In all cases the patient was starved for four to eight hours prior to operation and the biopsies were taken from the second part of the duodenum immediately proximal to the opening of the common bile duct. The tissue was prepared both for light and electron microscopy.By light microscopy Brunner’s glands in the human appear as masses of coiled tubules in the submucosa with ducts opening into the bases of intestinal glands. Component cells are characteristically mucous in type with dark, irregular, basally-located nuclei and clear, foamy cytoplasm.

Alumina Porous Ceramics: Mathematical Behavior at Different Commercial Starch Concentration

2008 ◽  
Vol 591-593 ◽  
pp. 442-447 ◽  
Author(s):  
Rodrigo Sampaio Fernandes ◽  
Élson de Campos ◽  
José Luiz Minatti ◽  
Jerusa Góes Aragão Santana ◽  
Rogério Pinto Mota
Keyword(s):  
Porous Ceramics ◽  
Mechanical Resistance ◽  
Flexural Test ◽  
Exponential Equation ◽  
Weibull Statistics ◽  
Starch Concentration ◽  
First Order ◽  
Porosity Effect ◽  
Mathematical Behavior ◽  
Starch Consolidation

Several researches have been developed in order to verify the porosity effect over the ceramic material properties. The starch consolidation casting (SCC) allows to obtain porous ceramics by using starch as a binder and pore forming element. This work is intended to describe the porous mathematical behavior and the mechanical resistance at different commercial starch concentration. Ceramic samples were made with alumina and potato and corn starches. The slips were prepared with 10 to 50 wt% of starch. The specimens were characterized by apparent density measurements and three-point flexural test associated to Weibull statistics. Results indicated that the porosity showed a first-order exponential equation e-x/c increasing in both kinds of starches, so it was confirmed that the alumina ceramic porosity is related to the kind of starch used.

Studies on the association between Noteia anomala and Hormosira banksii (Phaeophyta)

1980 ◽  
Vol 28 (2) ◽  
pp. 239 ◽  
Author(s):  
ND Hallam ◽  
MN Clayton ◽  
D. Parish
Keyword(s):  
Cell Walls ◽  
Close Contact ◽  
Light And Electron Microscopy ◽  
Biological Significance ◽  
Adjacent Cell ◽  
Tide Pool ◽  
Prolonged Culture ◽  
The Common ◽  
The Relationship ◽  
Sexually Mature

Anatomical, ultrastructural, ecological and physiological aspects of the relationship between the common brown alga, Hormosira banksii, and the obligate epiphyte Notheia anomala are described. The highest frequencies of infection by N. anomala occur in sexually mature H. banksii in tide-pool populations. Male and female H. banksii are equally affected, and the most common sites of infection are the receptacles where N. anomala attaches around the ostiole rather than within the conceptacle. Prolonged culture of N. anomala was only possible with media containing a filtered extract of the receptacles of the host species. Light and electron microscopy of the regions of thallus connecting N. anomala and H. banksii showed a wedge-shaped incursion of N. anomala in the H. banksii thallus, and very close contact between the adjacent cell walls of host and epiphyte, but there were no protoplasmic connections. The biological significance of the relationship between N. anomala and H. banksii is discussed.

scholarly journals THE GOLGI APPARATUS IN NEURONS AND EPITHELIAL CELLS OF THE COMMON LIMPET PATELLA VULGATA

1957 ◽  
Vol 3 (5) ◽  
pp. 779-796 ◽  
Author(s):  
Dennis Lacy
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Golgi Apparatus ◽  
Light And Electron Microscopy ◽  
Neutral Red ◽  
Continuous Phase ◽  
Common Source ◽  
Patella Vulgata ◽  
Dense Substance ◽  
The Common

1. In view of widely diverse views held about the identity and structure of the Golgi apparatus in neurons of Mollusca, particularly gastropods, a study has been made on neurons of the common limpet, Patella vulgata, both by light and electron microscopy. A report is given also of observations made on epithelial cells of Patella by electron microscopy. 2. As revealed by Kolatchev's method, the Golgi apparatus in neurons consists basically of black filaments lying to one side of the nucleus. The filaments generally anastomose to form networks of various complexity. Rarely some cells contain only discrete filaments. Associated with some of the filaments is a weakly osmiophilic substance identified as archoplasm. Kolatchev's method also revealed spheroidal bodies (neutral red bodies, "lipochondria," etc.). 3. It has not been possible to demonstrate the Golgi apparatus using either iron-haematoxylin or Sudan black. 4. Examination of Kolatchev's preparations by electron microscopy has revealed that some of the Golgi filaments consist of chromophilic and chromophobic components. The chromophilic component consists of dense lamellae. 5. After fixation in buffered osmium tetroxide solution and examination by electron microscopy, it has been concluded that (a) the chromophilic component of the Golgi apparatus corresponds to a system of paired membranes (which usually enclose an inner dense substance), (b) the chromophobic component corresponds to a substance lying within small dilations of the paired membrane, and (c) the archoplasm corresponds to numerous small vesicles. 6. The paired membranes branch, anastomose, and can often be traced back to a common source. They are interpreted as lamelliform folds, and occasionally tubular processes, of essentially a single Golgi membrane. In cells containing a Golgi network it is suggested that the membrane extends through the whole of the apparatus in such a way that the substance it encloses may be regarded as being in a continuous phase. 7. Epithelial cells of Patella contain a juxtanuclear Golgi apparatus with an ultrastructure similar to that described for neurons.

Fine structure of the pecten oculi of the common loon (Gavia immer)

1986 ◽  
Vol 64 (10) ◽  
pp. 2181-2186 ◽  
Author(s):  
C. R. Braekevelt
Keyword(s):  
Electron Microscopy ◽  
Basal Lamina ◽  
Light And Electron Microscopy ◽  
Gavia Immer ◽  
Common Loon ◽  
Luminal Surface ◽  
Pecten Oculi ◽  
The Common ◽  
Diving Bird ◽  
Region Form

The pecten oculi of a diurnally active diving bird, the common loon (Gavia immer), was studied by light and electron microscopy. In this species the pecten consists of a pleated, highly vascular, pigmented structure that is situated over the optic nerve head and projects into the vitreous chamber. Fourteen to 15 accordion folds are joined apically by a heavily pigmented bridge of tissue, which holds the pecten in a fanlike shape, widest at the base. A distinct basal lamina encloses the entire pecten. Within each fold are numerous capillaries, melanocytes, and larger blood vessels that are often difficult to differentiate as either arterioles or venules. The capillaries are surrounded by basal laminae separated from the endothelial cells by several fibrillar layers. Pericytes are often enclosed within the basal lamina. These capillaries display numerous microfolds on their luminal surface, with a slightly reduced number of processes on the abluminal border. The endothelial cell body is extremely thin and most organelles are in the paranuclear region. The melanocytes, which are most numerous in the bridge region, form an incomplete sheath around these capillaries. As in other species, the morphology of the pecten in the loon indicates a heavy involvement in the transport of materials.

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