scholarly journals Studies on Shell Formation

1958 ◽  
Vol 4 (3) ◽  
pp. 275-280 ◽  
Author(s):  
Tadashi Tsujii ◽  
D. Gordon Sharp ◽  
Karl M. Wilbur
Keyword(s):  
Crystal Size ◽  
Random Distribution ◽  
Outer Edge ◽  
Crystal Surfaces ◽  
Submicroscopic Structure ◽  
Fine Grained ◽  
Matrix Surface ◽  
The Matrix ◽  
Granular Matrix ◽  
Crystal Arrangement

The submicroscopic structure of the growing surface of the shell of the oyster, Crassostrea virginica, was studied by means of shadowed replicas. The outer edge of the prismatic region consists of a fine grained matrix enclosing crystals, the surfaces of which show a finely pebbled structure. Crystal size varies continously from 0.01 µ to 8 µ. The matrix surface shows no evidence of fibrous structure. The outer portions of the prismatic region exhibit a tile-like arrangement of large crystals separated by granular matrix 0.02 to 0.08 µ in thickness. The exposed crystal surfaces have indentations of varying form which appear as roughly parallel grooves spaced at intervals of approximately 0.3 µ. The final form of this region is believed to result from the random distribution of crystal seeds, which grow without orientation and through coalescence and growth come into contact, producing polygonal areas. The crystal arrangement of the nacreous region is one of overlapping rows of crystals in side to side contact, and with one end of each crystal free, permitting continued increase in length. Crystal angles and plane indices are presented.

scholarly journals Studies on the Codeposition of SiC Nanopowder with Nickel, Cobalt, and Co-Ni Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ewa Rudnik ◽  
Sławomir Syrek
Keyword(s):  
Corrosion Current ◽  
Metallic Ions ◽  
Alloy Matrix ◽  
Cobalt Ions ◽  
Fine Grained ◽  
Ni Alloys ◽  
Nickel Cobalt ◽  
Matrix Surface ◽  
Nickel Deposits ◽  
The Matrix

Electrodeposition of SiC nanopowder (approximately 120 nm) with nickel, cobalt, and Co-Ni alloy matrix was studied. It was found that particles suspended in the bath affect slightly the reduction of metallic ions. Incorporation of the ceramic particles was governed mainly by the morphology of the matrix surface, while no strict correlation between the amount of cobalt ions adsorbed on the powder and the SiC content in the composites was found. Microhardness of nickel deposits was 585±5 HV, while for cobalt-rich coatings (84–95 wt.% Co) the values were in the range of 260–290 HV, independently of the SiC content in the coatings. Fine-grained nickel deposits were characterized by good corrosion resistance, while cobalt and Co-Ni alloys showed high corrosion current densities.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

Dependence of Granular Matrix Demagnetizing Factor on the Matrix Relative Size

2015 ◽  
Vol 1083 ◽  
pp. 32-36 ◽  
Author(s):  
Alexander Sandulyak ◽  
Anna Sandulyak ◽  
Petr Shkatov
Keyword(s):  
Magnetic Permeability ◽  
Relative Size ◽  
Dramatic Effect ◽  
Comparative Estimate ◽  
Magnetic Filter ◽  
Wide Range ◽  
Demagnetizing Factor ◽  
The Matrix ◽  
Granular Matrix ◽  
Operating Units

We note that for a wide range of porous, especially granular, ferromagnetics used as matrices of magnetic filter-separators, there is still an issue of defining their demagnetizing factor N which has a dramatic effect on the values of average magnetic permeability of these operating units of filter-separators. The work aims at filling the existent gaps in the issue, we supply N values depending on the relative size of such magnets as well as a respective generalizing phenomenological dependence which is characterized by an exponential realtion between the demagnetizing factor and relative size radical. The established relation allows obtaining real values of magnetic permeability of a short filter matrix thus providing an unbiased comparative estimate of its technological workability.

Preparation of Fine-Grained Corundum Powders with Given Properties: Crystal Size and Habit Control

2018 ◽  
Vol 52 (5) ◽  
pp. 879-886 ◽  
Author(s):  
G. P. Panasyuk ◽  
L. A. Azarova ◽  
V. N. Belan ◽  
E. A. Semenov ◽  
M. N. Danchevskaya ◽  
...  
Keyword(s):  
Crystal Size ◽  
Fine Grained

Recent Advances in Biohybrid Materials for Tissue Engineering and Regenerative Medicine

2016 ◽  
Vol 04 (01) ◽  
pp. 1640001 ◽  
Author(s):  
Ying Wan ◽  
Xing Li ◽  
Shenqi Wang
Keyword(s):  
Tissue Engineering ◽  
Regenerative Medicine ◽  
Cell Function ◽  
Rapid Prototype ◽  
Artificial Organs ◽  
Specific Cell ◽  
Cell Matrix ◽  
Matrix Surface ◽  
The Matrix ◽  
Cell Matrix Interactions

Biohybrid materials play an important role in tissue engineering, artificial organs and regenerative medicine due to their regulation of cell function through specific cell–matrix interactions involving integrins, mostly those of fibroblasts and myofibroblasts, and ligands on the matrix surface, which have become current research focus. In this paper, recent progress of biohybrid materials, mainly including main types of biohybrid materials, rapid prototype (RP) technique for construction of 3D biohybrid materials, was reviewed in detail; moreover, their applications in tissue engineering, artificial organs and regenerative medicine were also reviewed in detail. At last, we address the challenges biohybrid materials may face.

Microstructure of Friction Stir Processed Mg-Y-Zn Alloy

2007 ◽  
Vol 558-559 ◽  
pp. 777-780 ◽  
Author(s):  
Taiki Morishige ◽  
Masato Tsujikawa ◽  
Sung Wook Chung ◽  
Sachio Oki ◽  
Kenji Higashi
Keyword(s):  
Equal Channel Angular Extrusion ◽  
Second Phase ◽  
Ingot Metallurgy ◽  
Friction Stir ◽  
Fine Grained ◽  
Probe Diameter ◽  
Fine Grain ◽  
Second Phase Particles ◽  
The Matrix ◽  
Zn Alloy

Friction stir processing (FSP) is the effective method of the grain refinement for light metals. The aim of this study is to acquire the fine grained bulk Mg-Y-Zn alloy by ingot metallurgy route much lower in cost. Such bulk alloy can be formed by the superplastic forging. The microstructure of as-cast Mg-Y-Zn alloy was dendrite. The dendrite arm spacing was 72.5 [(m], and there are the lamellar structures in it. FSP was conducted on allover the plate of Mg-Y-Zn alloy for both surfaces by the rotational tool with FSW machine. The stirring passes were shifted half of the probe diameter every execution. The dendrite structures disappeared after FSP, but the lamellar structure could be observed by TEM. The matrix became recrystallized fine grain, and interdendritic second phase particles were dispersed in the grain boundaries. By using FSP, cast Mg-Y-Zn alloy could have fine-grained. This result compared to this material produced by equal channel angular extrusion (ECAE) or rapid-solidified powder metallurgy (RS P/M). As the result, as-FSPed material has the higher hardness than materials produced by the other processes at the similar grain size.

Age and Geochemical Studies of the Snyder Breccia, Coastal Labrador

1975 ◽  
Vol 12 (3) ◽  
pp. 361-370 ◽  
Author(s):  
Jackson M. Barton Jr. ◽  
Erika S. Barton
Keyword(s):  
Trace Element ◽  
North Atlantic ◽  
Layered Intrusion ◽  
Basement Complex ◽  
Fine Grained ◽  
The North ◽  
Isotopic Analyses ◽  
The Matrix ◽  
The North Atlantic ◽  
Geochemical Studies

The Snyder breccia is composed of angular to subrounded xenoliths of migmatites and amphibolites in a very fine grained matrix. It is apparently intrusive into the metasediments of the Snyder Group exposed at Snyder Bay, Labrador. The Snyder Group unconformably overlies a migmatitic and amphibolitic basement complex and is intruded by the Kiglapait layered intrusion. K–Ar ages indicate that the basement complex is Archean in age (> 2600 m.y. old) and that the Kiglapait layered intrusion was emplaced prior to 1280 m.y. ago. Major and trace element analyses of the matrix of the Snyder breccia indicate that while it was originally of tonalitic composition, later it locally underwent alteration characterized by loss of sodium and strontium and gain of potassium, rubidium and barium. Rb–Sr isotopic analyses show that this alteration occurred about 1842 m.y. ago, most probably contemporaneously with emplacement of the breccia. The Snyder Group thus was deposited sometime between 2600 and 1842 m.y. ago and may be correlative with other Aphebian successions preserved on the North Atlantic Archean craton.

scholarly journals 9,10-ANTHRAQUINONE-2,6-DISULFONIC ACID DISODIUM SALT/ EPOXY GRAPHITE COMPOSITE FOR ANODE IN MICROBIAL FUEL CELL

2017 ◽  
Vol 79 (5-3) ◽  
Author(s):  
Mimi Hani Abu Bakar ◽  
Neil F Pasco ◽  
Ravi Gooneratne ◽  
Kim Byung Hong
Keyword(s):  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Conductive Filler ◽  
Internal Resistance ◽  
Disodium Salt ◽  
Disulfonic Acid ◽  
Graphite Composite ◽  
Design Flexibility ◽  
Matrix Surface ◽  
The Matrix

Properties such as electrical conductivity, low resistivity, chemicals and corrosion resistance are mostly found in carbon based materials. Epoxy resin is excellent for electrical insulation and can be used as a conductor with the addition of conductive filler. Combinations of carbon and epoxy show qualities of a conductive electrode, mechanically strong with design flexibility and thus makes them suitable as electrodes in microbial fuel cell (MFC). In this study, graphite-epoxy composites were fabricated with multi-walled carbon nanotube (MWCNT) embedded in the matrix surface. 9,10-Anthraquinone-2,6-disulfonic acid disodium salt/polypyrrole (PPy/AQDS) was used as mediator, covalently electrografted on electrode’s surface. Electrochemical stability of anodes during continuous operation were measured in air-cathode MFCs. It appears that maximum power in MFC could be increased up to 42% with surface modification using PPy/AQDS. Internal resistance (Rint) could be reduced up to 66% with the inclusion of MWCNT. These findings show that a one-day fabrication of a-ready-to-use conductive electrode is possible for graphite content between 70-80% (w/w).

Composition, technology and provenance of Roman pottery fromNapoca(Cluj-Napoca, Romania)

Clay Minerals ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 621-641 ◽  
Author(s):  
Ágnes Gál ◽  
Corina Ionescu ◽  
Mátyás Bajusz ◽  
Vlad A. Codrea ◽  
Volker Hoeck ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Raw Materials ◽  
Ceramic Body ◽  
Polarized Light ◽  
Raw Material ◽  
Gradual Transition ◽  
X Ray ◽  
Fine Grained ◽  
The Matrix ◽  
Technological Constraints

ABSTRACTSecond-century CE (common era) household pottery sherds found in the city ofNapoca(present day Cluj-Napoca, Romania) in Roman Dacia were investigated by polarized light optical microscopy, X-ray powder diffraction, Fourier-transform infrared spectroscopy and cold field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to obtain information on technology, raw materials and site of production. Compositionally, all samples are similar with comparable fine and semi-fine microstructures and oriented microtextures. Optically, there is a gradual transition from microcrystalline to an amorphous illitic-muscovitic matrix. The small aplastic inclusions are mostly quartz and feldspar. Fine-grained carbonate aggregates are distributed inhomogeneously in the ceramic body. Well-preserved Middle Miocene foraminifera tests are characteristic of the ceramics. The gradual thermal changes of the matrix and the newly formed phases upon firing, such as ‘ceramic melilite’, Fe-gehlenite, clinopyroxene, glass, hematite and some maghemite support inferences regarding the technological constraints in producing the pottery. The firing took place in a mostly oxidizing atmosphere and the temperature extended from at least 850°C to >900°C. The Middle Miocene marly clay from the area surrounding the site shows similar mineralogical and micropalaeontological contents to those of the ceramic specimens and is the best candidate for the raw material used for local production of the Roman pottery.

The Microstructure and Superplastic Behavior of Clean Mechanically Alloyed Titanium–Titanium Boride Alloys

1999 ◽  
Vol 601 ◽  
Author(s):  
A.P. Brown ◽  
R Brydson ◽  
C. Hammond ◽  
A. Wisbey ◽  
T.M.T. Godfrey
Keyword(s):  
Sheet Material ◽  
Hot Isostatic Pressing ◽  
Superplastic Forming ◽  
Titanium Boride ◽  
Production Cycle ◽  
Microstructural Development ◽  
Mechanically Alloyed ◽  
Boron Powder ◽  
Fine Grained ◽  
The Matrix

AbstractThe superplastic forming (SPF) of titanium alloys is an established technology. A reduction in grain size from that of the typical sheet materials would lead to enhanced SPF properties and hence a reduction in production cycle times. This study describes the microstructural development and superplastic behaviour of fine-grained Ti-6%Al-4%V alloys. Ball-milling Ti-6%Al-4%V powder produces a nanocrystalline material; however on consolidation by hot isostatic pressing rapid grain growth occurs. Addition of boron powder during milling leads to boride precipitates in the matrix of the consolidated alloy. The precipitates are dispersed inhomogeneously, resulting in localized grain refinement. Superplastic testing revealed cavitation formation but in comparison to conventional sheet material, large elongations were achieved at relatively high strain rates.

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