Extrusion Of Bodies Research Articles

Source Depth Determination of the Ningi-Burra Younger Granite Complex North-Eastern Nigeria from Aeromagnetic Data

Source Parameter Imaging (SPI) of aeromagnetic data covering an area within Birnin-Kudu Sheet 105 SE, Gwaram Sheet 106 SW, Kalatu Sheet 127 NE and Kaffin Madaki sheet 128 NW, bounded between Latitudes 10o 55’ N to 11o 10’ N and Longitudes 9o20’ E to 9o 35’ E. The application of Source Parameter Imaging (SPI) method revealed depth ranging from 64.704m to 538 to 777m, map of the depth estimates obtained from the SPI solution plot superimposed on the residual magnetic field intensity map of the area. The blue to cyan colours (64.704m to 111.520M) indicates the shallowest portions of the basement, the Green to Yellow colours (115.773m to 187.186m) represent the intermediate depth, while the Red to Pink coloured (201.698m to 538.77m) represent the highest peak of the area which are the deepest areas. The results from the SPI study indicate that deep seated bodies (dykes) dominated the area. Other Euler deconvolution solutions were also obtained by first selecting a magnetic structural index of zero (i.e., SI=0), followed by SI=0, SI=1, SI=2, and SI=3. This is based on the concept of Euler homogeneity, a description of scaling behavior in potential-field depth analysis. The magnetic structural index (SI=0) represents the depth of the contact with basement, which is as low as -131.093m and the highest is at 329.960m The best clustering solution was obtained by selecting a structural index of one (i.e., SI = 1) shows that the solution plotted as clustered in the region where the geological structures are located in the depth range of 8.707m to 1370.815m, which indicates that the deep magnetic bodies are concentrated at the peripheral side of the ring complex. The deeper magnetic sources are at the depth of -163.723m to the basement, while the highest depth to the shallower magnetic source in the area is 700.594m and represents the extrusive bodies in the area.

Natural sources and conditions of geological hydrogen generation (in the context of hydrogen depositssearches)

World energy problems can largely be solved in the event of discovering huge amounts of gaseous hydrogen in a free state, which is considered as a promising alternative to the reserves of traditional fossil fuel in the earth’s crust. However, the hydrogen industry’s development is inhibited by many challenges, in particular, in geology. Today there is neither strategy for exploration activity nor resource evaluation due to the lack of relevant experience and practical recommendations aimed at geological hydrogen. The purpose of the work is to establish and analyze potential ways and geological conditions for the formation, migration, and accumulation of hydrogen of natural origin in the earth’s crust for the further justification of the concept of the search of free hydrogen accumulation. The author has considered all possible theoretical natural sources and ways of generating hydrogen naturally. Its origin is generally assumed to magmatic, thermogenic, endogenous, biogenic, as well as one that is caused by radiolysis, decomposition of organic matter, the interaction of water with reducing agents in the mantle. All known possible ways of the genesis of free hydrogen in natural conditions are analyzed. Geologically controlled sources of natural hydrogen can be grouped according to the main processes: aqueous processes of hydrolysis (several processes including the oxidation of iron minerals, radiolysis, cataclasis and metamorphism; decomposition of organic matter (including thermal maturing); decomposition of hydrogen-containing compounds (in particular, methane and/or ammonia at metamorphisms); deep degassing of Earth’s interior. Potential location areas of free hydrogen in a geological environment are analyzed. Natural conditions for high/increased hydrogen content have basins with the presence of hydrocarbons, recent deposits with prolific organic, coal beds, zones of tectonic faults, extrusive magmatic bodies, alkaline magmatic complexes, geothermal fields, crystalline basements, geologic formation of rocks enriched with potassium, salt-bearing sections and ultrabasic rocks. Due to the uncertainty concerning the ways and conditions for generating hydrogen in the earth’s crust, geological searches and possible further study of hydrogen accumulations require a mix of methods and approaches used for traditional searches of hydrocarbon deposits – conventional oil and gas fields (source rocks, basin, cap) given the features of free hydrogen, in particular, mobility and reactive capacity of its molecule. Regardless of the genesis of hydrogen, the main search criteria should be focused on the ways of its migration and the availability of a basin and a cap. This approach maximally combines hypotheses competing among themselves (from the viewpoint of the genesis of hydrogen). It is required the geological structure with the corresponding basin and fluid trap (cap), which, unlike the fluid traps in the usual sense, should be not only impermeable but also chemically neutral in relation to hydrogen.

Preliminary assessment of the characteristics of Late Miocene - Quaternary intrusive and extrusive magmatism in the Tu Chinh - Vung May basin, southeastern continental shelf of Vietnam

Based on the seismic and well dataset provided by the Vietnam Petroleum Institute (VPI), the authors have mapped and described the characteristics of the distribution and morphology of magmatic bodies as well as relatively dated them in the Tu Chinh - Vung May basin and adjacent areas. To distinguish magmatic bodies from other amplitude anomalies such as gas zone or carbonate build-up/layers, multiple criteria were used such as cross-cutting relationship, associated deformation of surrounding strata, morphology and geological relationship between different magmatic bodies. Intrusive bodies are usually sheet-like or saucer-shaped sills that cross-cut strata and even deform overlying strata, while extrusive bodies are usually cone-shaped vents/volcanoes or extensive lava sheets that conform to strata. The magmatic bodies often distribute in clusters around one or more magmatic conduits. Middle Miocene and older syn-rift faults controlled the pathway of the conduits. Magmatic bodies are more abundant closer to the East Sea spreading margin. Late Miocene - Quaternary magmatism is widespread in the study area in particular, and in the East Sea and adjacent areas in general. These activities took place after rifting and oceanic crust formation had ended, which is characteristic of magma-poor margins.

Basement geology derived from gravity anomalies beneath the Benue Trough of Nigeria

New gravity data over the lower part of the Benue Trough revealed two important anomalies that were not recognized from the past gravity data. The anomalies are the central positive gravity of the order of about + 40 mGal around the area of Oturkpo which is interpreted due to the contribution of an igneous intrusive (2.76 g/cc) tentatively syenite intrusion. The other, which is the negative gravity anomaly (− 33 mGal), is consistent with the rifted Anambra basin where thicker sediment-fill of 8.4 km is calculated. The interpretation of the gravity anomalies beneath the Peninsula Nigerian Benue Trough revealed that intrusions are hardly separated from the anticlinal folded axes. This could suggest the unstable geological units of the Peninsula Nigerian Benue Trough. In this paper, we have also mapped some volcanic extrusive bodies around the Gboko basement and Oban massif basement, north of Calabar area.

Formation and degradation of large extrusion bodies in Tetrahymena thermophila: The role of intramacronuclear microtubules in chromatin segregation

Large extrusion bodies (EBs) in Tetrahymena thermophila were induced by treatment with aphidiocolin (APH), followed by transfer of the cells to a drug free medium. APH induces over-replication of DNA and reversible cell division arrest (Kaczanowski and Kiersnowska, 2011). After treatment the cells were transferred to a drug free medium, and a central granule of chromatin (a prospective EB) surrounded by microtubules developed inside the macronucleus. Subsequently the chromatin of the central granule appeared in the middle region of the dividing macronucleus, and it was later extruded as an EB. The remaining chromatin segregated to opposite ends of the elongating macronucleus and was separated from the chromatin destined for the EB by intramacronuclear microtubules. TUNEL assay (terminal deoxynucleotidyl transferase dUTP nick end labeling]) and in vivo acridine orange (AO) staining showed that the EBs underwent apoptotic-like degradation and autophagy similar to that observed in programmed nuclear death (PND) of the old macronucleus in conjugant cells. Overall, based on the data obtained in this study we proposed the hypothesis that over- replication of DNA induced by APH results in the appearance of defective DNA copies, that are not segregated to the opposite regions of dividing macronucleus and are destined for EBs.

Birth of an oceanic spreading center at a magma-poor rift system

Oceanic crust is continuously created at mid-oceanic ridges and seafloor spreading represents one of the main processes of plate tectonics. However, if oceanic crust architecture, composition and formation at present-day oceanic ridges are largely described, the processes governing the birth of a spreading center remain enigmatic. Understanding the transition between inherited continental and new oceanic domains is a prerequisite to constrain one of the last major unsolved problems of plate tectonics, namely the formation of a stable divergent plate boundary. In this paper, we present newly released high-resolution seismic reflection profiles that image the complete transition from unambiguous continental to oceanic crusts in the Gulf of Guinea. Based on these high-resolution seismic sections we show that onset of oceanic seafloor spreading is associated with the formation of a hybrid crust in which thinned continental crust and/or exhumed mantle is sandwiched between magmatic intrusive and extrusive bodies. This crust results from a polyphase evolution showing a gradual transition from tectonic-driven to magmatic-driven processes. The results presented in this paper provide a characterization of the domain in which lithospheric breakup occurs and enable to define the processes controlling formation of a new plate boundary.

Obtaining a fish minced feed by the method of cryoextrusion from frozen fish raw materials

Developed the technology of obtaining a fish minced feed (cryo minced fish feed) by the method of cryoextrusion using by the utility model extrusion of a piston-type cold working bodies for grinding the fish raw material in a frozen state. Justified the possibility of replacement in the standard technology of production the feed from the minced fish such technological operations as the defrosting and subsequent grinding of raw materials to the operation like a cold extrusion or cryoextrusion. Used the shape of the holes of the die for forcing the raw material in the form of “hourglass” with a diameter of 7 mm, the length of the process of pushing – 40 seconds. Determine the actual losses of raw material in the milling process meth of cryoextrusion ranging from 1% to 2.5%, including the losses when cutting block for the preparation of raw materials to piercing. It is established that the finished product – cryo minced fish feed, has a homogeneous grinding, juicy, crumbly texture, the temperature in the thickness of the product is not changed and equal to the temperature of raw materials before processing, that is minus 18 °C. Developed the principal technological scheme of obtaining the cryo minced fish feed by the method of cryoextrusion. The calculation of material balance in the production of beef has shown that the use of the new method will allow to increase the product yield up to 99%. Based on the studies of the chemical composition of fish and feed of mince obtained by traditional and developed methods established that the protein content in the cryo minced fish feed remains unchanged. Developed draft technical specifications for the production of cryo minced fish feed and technological instructions for the production of cryo minced fish feed for fodder purposes, and also prepared the application for the patent named “Obtaining cryo minced fish feed from the frozen fish by the method of cryoextrusion”.

Reply to Discussion on ‘Late Cenozoic geological evolution of the northern North Sea: development of a Miocene unconformity reshaped by large-scale Pleistocene sand intrusion’, Journal of the Geological Society , 170, 133–145

Knowledge of small sand injection is far from new (Murchison 1827; Hurst et al . 2011) but that intrusive and extrusive bodies of sand can be more than 100 m thick and extend for kilometres is considered unlikely by Rundberg & Eidvin (2015), who discuss our paper (Loseth et al . 2013). Their discussion disagrees with our interpretation of the origin of these sand bodies and instead favours their previously proposed models (Eidvin & Rundberg 2001; Rundberg & Eidvin 2005). They claim that (1) the early Pleistocene sandstones are turbiditic sands deposited at the toe of the glaciomarine shelf clinoform foresets and not extrusive sands; (2) the Oligocene sandstones, located below mounds at the top Hordaland Group Unconformity, are in situ deposits representing turbiditic gravity sands shed from the Shetland Platform and not intrusive sands; and (3) the top Hordaland Group Unconformity in the northern North Sea was formed by submarine erosion and not during subaerial exposure. We have studied rock properties of Eocene to Pleistocene claystones and sandstones (Oygarden et al . 2015), carried out detailed seismic and well studies in the North Sea (Loseth et al . 2003, 2012, 2013), studied the physical processes of injection, extrusion and depletion of sand in analogue experiments (Rodrigues et al . 2009), and studied outcrops of intrusive sandstones through sand injection research consortiums (e.g. Hurst et al . 2006, 2011; Vigorito et al . 2008; Cartwright 2010; Scott et al . 2012). Our seismic and well observations above the Snorre and Visund fields were in conflict with existing geological models and therefore we proposed new models. This reply builds on knowledge of how the seismic expression of sandstone varies with the type of embedding claystone. Oygarden et al …

Potential Application of Triploidy Induction in Important Aquatic Species in South East Asia

Triploidy, a stage of having 3 sets of chromosomes, occurs naturally in fish. Induction of triploidy is possible by subjecting newly fertilized eggs to sub-lethal conditions prior to the extrusion of polar bodies. The purposes of the induction include improving growth and/or obtaining sterile animals for various purposes. This article gives a brief background of triploid induction in aquatic animals, performances of triploid and collective information on triploidy induction in aquatic species native to South East Asia, and future direction.

Cascading Adjacent Level Vertebral Compression Fractures Necessitating a Series of Eleven Kyphoplasties.

Vertebral kyphoplasty is a procedure used for the treatment of compression fractures. While early randomized-controlled trials were equivocal regarding its benefits, more recent RCTs have shown favorable results for kyphoplasty with regard to pain relief, functional recovery, and health-care related quality of life compared to control patients. Risks of kyphoplasty include but are not limited to cement extrusion, infection, hematoma, and vertebral body fracture of adjacent levels. We describe a case of a 66-year-old male attorney who underwent eleven kyphoplasties in an approximately one-year period, the majority of which were for fractures of vertebrae adjacent to those previously treated with kyphoplasty. Information on treatment was gathered from the patient's hospital chart and outpatient office notes. Following the last of the eleven kyphoplasties (two at T8, one each at all vertebrae from T9 to L5), the patient was able to function without pain and return to work. His physiologic thoracic kyphosis of 40 degrees prior to the first procedure was maintained, as were his lung and abdominal volumes. We conclude that kyphoplasty is an appropriate procedure for the treatment of vertebral compression fractures and can be used repeatedly to address fractures of levels adjacent to a previous kyphoplasty.

The Archean komatiite-hosted, PGE-bearing Ni–Cu sulfide deposit at Vaara, eastern Finland: evidence for assimilation of external sulfur and post-depositional desulfurization

Archean komatiites host important resources of Ni, Cu, Co, and PGE, particularly in Western Australia and Canada. In Finland, several small, low-grade sulfide deposits have been found in komatiites, including the ca. 2.8 Ga Vaara deposit in the Archean Suomussalmi greenstone belt. It occurs in the central part of the serpentinized olivine cumulate zone of a komatiitic extrusive body and is composed of disseminated interstitial sulfides consisting of pyrite, pentlandite, millerite, violarite, and chalcopyrite accompanied by abundant magnetite. Although currently subeconomic, the mineralization is interesting due to the very high chalcophile element contents of the sulfide fraction (38 wt% Ni, 3.4 wt% Cu, 0.7 wt% Co, 22.4 ppm Pd, and 9.5 ppm Pt). The sulfides occur in relatively Cr-poor olivine cumulates suggesting involvement of a chromite-undersaturated magma. The parental magma was an Al-undepleted komatiite with an estimated MgO content of at least 24 wt%. In contrast to the common komatiite types in the eastern Finland greenstone belts, the Vaara rocks are moderately enriched in LREE relative to MREE, suggesting that crustal contamination played an important role in the genesis of the Vaara deposit. Multiple sulfur isotope data reveal considerable mass-independent sulfur isotope fractionation both in country rock sedimentary sulfides (Δ33S ranges from −0.50 to +2.37 ‰) and in the Vaara mineralization (Δ33S ranges from +0.53 to +0.66 ‰), which provides strong evidence for incorporation of crustal sulfur. Extensive replacement of interstitial sulfides by magnetite and the presence of millerite- and violarite-bearing, pyrrhotite-free sulfide assemblages indicate significant post-magmatic, low-temperature hydrothermal oxidation of the primary magmatic pyrrhotite-pentlandite-chalcopyrite assemblages and associated sulfur loss that led to a significant upgrading of the original metal tenors of the Vaara deposit.

World's largest extrusive body of sand?

Using three-dimensional seismic and well data from the northern North Sea, we describe a large (10 km 3 ) body of sand and interpret it as extrusive. To our knowledge, this is the world9s largest such sandbody. It would bury Manhattan, New York (60 km 2 ), under 160 m of sand, or the whole of London, UK (1579 km 2 ), under 6 m of sand. This sand vented to the seafloor, when it was more than 500 m deep, during the Pleistocene glacial period. The sandbody (1) covers an area of more than 260 km 2 , (2) is up to 125 m thick, (3) fills low areas around mounds, which formed when underlying sand injectites lifted the overburden, (4) wedges out, away from a central thick zone, (5) is locally absent along irregular ditches, 20 km long and up to 50 m deep, which overlie feeders on the flanks of the mounds, and (6) consists of fine-grained to medium-grained, sub-rounded to rounded grains. We compare the distribution of the sand with the results of scaled physical experiments. In our interpretation, high fluid pressure fractured the regional Hordaland Group seal in the study area, so that fluidized sand moved rapidly to the seafloor through fissures on the flanks of underlying mounds, mixed with seawater, and formed lateral gravity currents. These transported the sand as much as 8 km away from the blow-out fissures and formed extruded sand sheets. Large extrusive sands represent a new type of economically interesting reservoir.

Discovery of Eocene adakites in Primor’e

This paper presents the first results of petrochemical and geochemical studies (by the ICP-MS technique) of adakites comprising a small extrusive body in the Ilistaya River basin (West Primor’e). Based on the data of radioisotopic dating (K-Ar method), the age of adakites corresponds to the Middle Eocene (45.52 ± 1.1 Ma). In terms of the content of most microelements and the value of the Sr/Y ratio, the discussed rocks are close to Paleogene adakites from northwest China, the Kitakami massif in Japan, and the northwestern margin of North America; these rocks are attributed to gaps in the subducted plate (slab windows). Additionally, the adakites found in Primor’e significantly differ from adakite-like rocks found in Tibet formed during melting of bottoms of the superthickened continental crust. Thus, this discovery proves the hypothesis about formation of slab windows at the Paleogene stage of the region’s evolution.

Ancient volcanic glasses of the Urals

The existing data on findings of unaltered volcanic glasses in the Paleozoic (from Late Ordovician to Late Devonian inclusive) volcanic strata of the Ural fold belt are systematized. These glasses have compositions that correspond to tholeiitic basalts, potassic alkaline basaltoids, andesites, and rhyolites. Relic portions of glasses of cenotypal appearance are preserved in thick glassy crusts of pillow lava flows, in fragments among hyaloclastites, in bombs from tuffs, and in extrusive bodies and dykes. Chemical analysis showed that the amount of dissolved water was low (1–1.3 wt %) in the primary tholeiitic magma and higher (8–10 wt %) in the magma that formed island-arc hyalobasalts, potassic alkaline basaltoids, andesites and rhyolites.

Geological and biological aspects of a find of natural alloy (Au-Cu-Ag) nanoparticles in Cenozoic zeolitized tuff of the Vanchinskaya basin (Primor’e Area)

Zeolites first described by Swedish researcher Kro� nshted more than 250 years ago still attract special attention today. These minerals are effectively applied in industry, agriculture, medicine, and for conserva� tion of surroundings with gradually spreading areas of their application. This is explained by unique adsorp� tive, ionexchange, and catalytic properties typical for this group of minerals, as well as by their thermal, chemical, and radiation stability. Artificial zeolites with constant composition and a strictly definite set of physicochemical properties are claimed in industry. Natural zeolites represented by polymineral zeolitized rocks (zeolitites) of various geneses are applied in agri� culture and medicine. In spite of their old origin, the mechanism of biological activity of these natural min� eral systems still is not sufficiently studied. The discov� ery of natural Au-Cu-Ag alloy microparticles in nat� ural zeolitites discussed in this paper is a rare mineral� ogical fact deserving special attention. The Vanchinskaya basin, one of the Cenozoic rift� ogene basins within the Eastern SikhoteAlin' volca� nic belt, has a relatively small size of 4 × 15 km. How� ever, the presence of coal and zeolites volcanogenic- sedimentary deposits filling it, high registered concen� trations of REE in coals (1), and its location on the southeastern flange of the Soyuznoe gold-silver deposit (2) are responsible for the unremitting scien� tific and practical interest in it over many years. Structurally this basin is a oneside riftogenic gra� ben of northwestern strike. Its southwestern side is separated by the Milogradovskii fault (thrust) clearly reflected in relief. The northeastern flange occurring along the fault as well is gentle. The western part of the basin is filled by pyroclastic (tephrogenic) and tuffo� gene-sedimentary coalbearing deposits of Pale� ocene-Early Eocene age. In the eastern part they are replaced and intruded by Middle Eocene volcanic rocks (tuffs, lavas, explosive breccias, and extrusive rhyolite and trachyandesite bodies). Zeolite mineralization within the basin has a strat� iform character. All zeolitite occurrences on the right side of the Vanchina-Ugol'nyi Brook including the Berezovoe manifestation studied in detail are of the same type by geological characteristics. They are rep� resented by outcrops (fragments) of the undercoal band of tuffaceous sandstone and tuffite in the compo� sition of tuffogene-sedimentary lake deposits and characterized by a significant admixture of mineral� ized plant detritus. According to the data of Xray structural analysis, the mineral composition of zeoli� tites of the Berezovoe manifestation comprises zeolites of the clinoptilolite-heulandite group (50-60%) and clay minerals of the smectite group (20-30%) with an admixture of quartz and feldspars. The visible thick� ness of the zeolitebearing band is ~20 m. Clearly reflected signs of active eating of rocks by wild ungulates as lick niches, as well as eaten away caves and individual nibbles on outcrops with typical tooth prints are observed in the coldfree period of the year on all natural outcrops of the zeolitized band within the Vanchinskaya basin. Traces of Manchurian deer are the most frequently observed among the traces left by animals in the places where they eat rocks and soils. As we mentioned before, most of the soils eaten by animals within the SikhoteAlin' are formed from zeolitized and argillized tuffogene-sedimentary rocks with clear signs of the presence of buried organic rem� nants (3). The hypothesis on the significance of organic materials in zeolitites as accumulators of bio� logically active chemical elements appeared long ago,

Association of spindle midzone particles with polo-like kinase 1 during meiosis in mouse and human oocytes

Polo-like kinase 1 (Plk1) has been reported to localize to the spindle midzone during meiosis in mouse oocytes. However, it has not been reported in human oocytes. In this study, the interaction of the meiotic structures and chromosome segregation in mouse and human oocytes were studied by time-lapse differential interference contrast microscopy. Using immunocytochemical studies, the localization of polo-like kinase 1 and its association with microtubules were examined during the extrusion of first and second polar bodies. It was found that Plk1 was localized in the spindle midzone in human oocytes at anaphase I and telophase I. Also, three-dimensional confocal laser microscopy showed that the meiotic spindle midzone contained numerous dot-like particles that were stained by anti-Plk1 antibody. These particles were aligned in the plane of the meiotic midzone in mouse and human oocytes.

Chromatin extrusion in resting encystment of Colpoda cucullus: A possible involvement of apoptosis‐like nuclear death

The extrusion of macronuclear chromatin is a remarkable characteristic during encystment in Colpoda, but the biological significance of this phenomenon has not been fully elucidated. Here we demonstrate that chromatin extrusion occurs with high frequency when encystment was induced by increasing Ca(2+) in growing cells in various stages of the cell cycle. The Feulgen-DNA reaction revealed that vegetatively growing cells have more macronuclear DNA than cells in the stationary phase, suggesting an association of macronuclear DNA content with the execution of chromatin extrusion. Using 4',6-diamidino-2-phenylindole (DAPI), we found that the size of the macronuclear extrusion body was reduced with time and eventually disappeared approximately 24h after encystment induction. In addition, oligonucleosome-sized DNA cleavage was confirmed to occur concomitant with the size reduction, suggesting that the extrusion body is selectively degraded, while the normal macronucleus remains alive. Combined use of acridine orange and Hoechst 33342 demonstrated that the extruded body was increasingly acidified before final resorption. These features are reminiscent of the nuclear degradation process in conjugating Tetrahymena, and therefore we conclude that chromatin extrusion in Colpoda might occur to adjust the macronuclear DNA content prior to encystment. In this way, it is similar to the apoptotic-like nuclear death that occurs during the conjugation of other ciliates.

Intrusives, Extrusives and Linear Magnetic Anomalies

Summary The definition of narrow linear oceanic magnetic anomalies resulting from dikes and associated extrusive bodies is compared to anomalies resulting from dikes without extrusives. It is shown that if the extrusive has a tapering cross-section with maximum thickness over the centre of extrusion, then peaks of' the resulting linear magnetic anomalies will possess a sharper definition than the anomalies due to a dike alone, provided the horizontal extent of the extrusive is of the order of, or less than, the depth of the ocean. Geomagnetic polarity events recorded by dike injection into a spreading oceanic crust will therefore not necessarily become ' smeared ' by the presence of substantial associated extrusive phases.

Microstructures and material properties of fibrous HAp/Al 2O 3–ZrO 2 composites fabricated by multi-pass extrusion process

Fibrous HAp/Al 2O 3–ZrO 2 composites were fabricated using the multi-pass extrusion process. In the 3rd and 4th passed extrusion bodies, fibrous microstructures were obtained. The 3rd and 4th passed Al 2O 3–ZrO 2 cores used as reinforcement, were about 35 and 4.5 μm in diameter, respectively. In the bodies sintered at over 1400 °C, the HAp decomposed and was transformed to β-TCP and TTCP, in which large numbers of pores were observed. The values of bending strength, Vickers hardness and fracture toughness of the 3rd passed HAp/Al 2O 3–ZrO 2 composites were 178 MPa, 325 Hv, and 3.4 MPa m 1/2, respectively while the values of the 4th passed bodies were 190 MPa, 405 Hv and 3.8 MPa m 1/2.

Magnetic minerals in the Martian crust

Using rock magnetism and thermal modeling, we evaluate the candidate minerals responsible for strong magnetic anomalies in the Terra Sirenum and Terra Cimmeria regions of Mars' southern highlands. We assume an early global dynamo field similar in strength to the present Earth's field, enduring about 500 Myr after accretion and core formation, and a basaltic crust containing no more than 4–7 weight% of magnetic minerals. Thermal evolution models with a wide variety of initial crustal thicknesses, distributions of radioactive elements, and thermal expansion coefficients all yield similar thermal histories for the crust: warming in the first ∼1000 Myr (due mainly to radioactive heating) followed by monotonic cooling for the remainder of Mars' history. Primary thermoremanent magnetization (TRM) acquired by intrusive and extrusive bodies during the first 500 Myr was in part thermally demagnetized by general crustal warming after the dynamo field disappeared, from 500 to 1000 Myr. The Curie point isotherms around 1000 Myr established the maximum depth of TRM‐bearing crust. Shock and heating due to impacts demagnetized the uppermost ∼10 km of the crust around the same time, resulting in potential magnetic layer thicknesses of 15–20 km for pyrrhotite, 40–50 km for magnetite, and 50–60 km for hematite. Other magnetic phases, such as iron and finely exsolved low‐Ti titanohematite, are possible but less likely in a basaltic crust under oxidizing conditions. The prime candidates, in order of likelihood, are single‐domain magnetite (0.2–0.4 volume% or 0.4–0.8 weight% required), single‐domain pyrrhotite (1–2 volume% or 2–4 weight%), and either multidomain (>15 μm) or 5–15 μm single‐domain hematite or a mixture of both (1.5–3 volume% or 3–6 weight%). A composite source with different combinations of these minerals at different depths is entirely possible. Viscous decay of TRM is difficult to assess without detailed knowledge of the distribution of minerals and blocking temperatures with depth but would increase the amounts of magnetic material required.