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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of Convective Heat Transfer in Deformed and Stratified Aquifers Associated with Frasch Thermal Mining (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This paper presents numerical experiments designed to simulate heat transfer in deformed, stratified geologic formations during Frasch thermal mining operations in the Delaware Basin. In such operations, superheated water (163°C) is injected into permeable ore zones to melt and mobilize sulfur. The efficiency of Frasch mining depends largely on various aspects of hydrologic controls and geologic factors, such as directing heat flow toward target areas and minimizing heat dissipation through advection and conduction in ore zones. Numerical modeling techniques were used in the search of an optimum thermal mining strategy for maximum sulfur recovery in various geologic settings present at the Culberson Mine, west Texas. The sample calculations illustrate heat transfer patterns in inclined, folded, and fractured geologic formations. Important results presented include the controls of geologic structures on directions and rates of heat transfer and ground water flow, a display of field evidence for the occurrence of thermal convection in permeable ore zones, and a depiction of heat transfer during a thermal mining operation proceeding down-dip along an inclined geologic unit. Modeling results and field data strongly support the hypothesis that thermal convection occurs and controls the heat transfer process in inclined ore zones. Simulations further suggest that the current thermal mining practice, which proceeds down-slope along an inclined ore zone, may result in lowered ultimate sulfur recovery. In this mining approach most heat migrates up-slope where the rock's permeability is enhanced by previous sulfur extraction, rather than down-dip toward the target area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1999.tb01137.x
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  • 2
    Electronic Resource
    Electronic Resource
    The fine structure of the polymorphic spermatozoa of Fusitriton oregonensis (Mollusca: Gastropoda), with notes on the cytochemistry of the internal secretions (1982)
    Springer
    Cell & tissue research 227 (1982), S. 235-255 
    Details
    ISSN: 1432-0878
    Keywords: Sperm polymorphism ; Ultrastructure ; Mollusca ; Prosobranchia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The prosobranch Fusitriton oregonensis exhibits an unusual form of sperm polymorphism. The viable, eupyrene sperm are attached in groups of about fifty to worm-shaped, apyrene, carrier sperm. There is a second apyrene sperm, which is lancet-shaped and has a different internal organization than the carrier, but does not transport eupyrene sperm. The eupyrene sperm are filiform (185 μm long), with a conical acrosome, elongate nucleus and midpiece. They contain large stores of glycogen in the principal piece, together with an unusually high proportion of protein. The latter is due to a complex interconnecting system of fibres that supports the tail internally. A distinct annulus is located, characteristically, at the junction between midpiece and principal piece. The carrier sperm has a core of about 112 axonemes that arise from basal bodies in the anterior end and extend through its entire length of 36 μm. The basal bodies have unstriated rootlets that are embedded in a granular cap. Large membrane-bound “yolk bodies” are arranged along the length of the carrier sperm, on either side of the median axonemal core. Dense bodies, which may be indigestible residues formed from the degeneration of the nucleus, are excreted by exocytosis. Individual carrier sperm are capable of “corkscrew” propulsion, resembling that of spirochaetes. The lancet sperm is three times as long as the carrier. The sixteen or so axonemes, which are arranged peripherally like a cage enclosing the cytoplasm, originate from a dense centriolar plate in the anterior end. The cytoplasm is filled with secretions including small yolk granules, dense bodies (also excreted), clear vesicles, and a membranated granular secretion that resembles mucus. The possible functions of the lancet and carrier sperm are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210883
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the polymorphic spermatozoa of a marine snail. 2. Genesis of the eupyrene sperm (1983)
    New York, NY : Wiley-Blackwell
    Gamete Research 7 (1983), S. 19-37 
    Details
    ISSN: 0148-7280
    Keywords: spermiogenesis ; centrioles ; Golgi body ; microtubules ; Gastropoda ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Spermiogenesis of the eupyrene sperm in the snail, Fusitriton oregonensis, was studied with light and electron microscopes. Endoplasmic reticulum, which encircles the nucleus in each spermatid, appears to connect with the Golgi body and to interconnect between adjacent spermatids via cytoplasmic bridges. It is suggested that as the Golgi body migrates around the nucleus the endoplasmic reticulum may circulate with it. The alignment of the proacrosome with the nucleus is effected by a 180° rotation of the Golgi body, after which it separates and migrates posteriorly with the residual cytoplasm. Each sperm possesses a well-developed intracellular digestive system as indicated by multivesicular bodies, residual bodies, and myeloid figures. Autophagy begins in the residual cytoplasm before it is released from the middle piece. Microtubules are found outside the nucleus and mitochondria during the final stages of spermiogenesis, when elongation is almost complete. These microtubules appear to be involved in the final shaping and twisting process, in which torsion is locked in the nucleus and the mitochondria spiral around the axoneme. The annulus attaches the distal centriole to the plasma membrane in the early spermatid and as flagellar production begins they move towards the implantation fossa at the base of the nucleus. There are two centrioles in the early spermatid, the distal centriole and procentriole. The small procentriole fuses with the distal centriole in the intranuclear canal to form the centriolar cap of the basal body. This cap is pushed through the end of the nuclear tube and is separated from the subacrosomal space by only the nuclear membranes.
    Additional Material: 31 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120070103
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