Experimental petrology of ancient lunar mare basalt Asuka-881757: Spinel crystallization as a petrologic indicator

The paucity of titanian chromites in lunar-meteorite basalt Asuka (A)-881757 is unusual compared to the general occurrence of co-existing chromites and ulvospinels in the Apollo and Luna mare basalts. The unique spinel crystallization of A-881757 is expected to hold a key to elucidate the crystallization and cooling episodes of the basalt. In this study, we investigated the possible reason for the missing chromite by conducting isothermal and cooling experiments on the bulk-rock composition of A-881757 and discuss the petrogenesis of the ancient low-Ti mare basalt in light of spinel crystallization. A series of isothermal experiments showed the A-881757 basalt magma is not saturated with chromite under the expected lunar oxygen fugacity condition (IW～IW-1). A peritectic reaction among chromite, melt, and pyroxene is present for A-881757 basalt magma under the more oxidized condition which is one or two log unit higher than the lunar condition. The cooling experiment successfully reproduced the chromian ulvospinels with similar compositions to those in A-881757. The result of the cooling experiments further implies that ulvospinels solely crystallized from highly-fractionated interstitial melts in the late crystallization stage. The disparity in the crystallization of the liquidus chromite between the low-Ti and very low-Ti basalts might reflect the difference of bulk Cr_2O_3 concentration. The low liquidus temperature and the paucity of the liquidus olivine in A-881757 infer that the A-881757 basalt represents a liquid derived from near-surface fractionation processes. Chromites might possibly have been present during that near-surface fractionation episode prior to the eruption of the magma

Mineralogical studies of lunar meteorite Yamato-793169, a mare basalt

A preliminary mineralogical study of the lunar meteorites Yamato (Y)-793169 and Asuka (A)-881757,which were apparently derived from a mare region of the Moon, has been performed to identify crystallization trends of their pyroxenes. Y-793169 is a crystalline basalt with similar basaltic components to lunar breccias EET87521 and Y-793274,containing strongly zoned Fe-Ca-rich pyroxenes. Their zoning trends in the pyroxene quadrilateral are closest to those found in the basaltic clast in an Apollo 16 breccia. Differentiation trends expressed by Ti/(Ti+Cr) versus Fe/(Fe+Mg) of Y-793169 and A-881757 pyroxenes are similar but they differ from those of EET87521. The Y-793169 trend starts at a more Mg-rich composition point than the A-881757 trend. Based on differences in textures and ranges of zoning trends, the pyroxene of A-881757 could represent growth deeper in the lava unit under conditions more closely approaching equilibrium, than Y-793169,which appears to have formed from a lava flow of similar bulk composition. Although Y-793169 has been described as the VLT basalt, some mesostases contain significant amounts of ilmenite and ulvospinel, together with fayalite, troilite, chromite and a silica mineral. Mg-rich pyroxenes as found in Y-793274 and EET87521 are not present in Y-793169 and A-881757 basalts

Association between Repair Functions and Interlocutor Relationship

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災害や感染症の被害を軽減する排水管理のガバナンス

要約のみTohoku University李玉友課

Mineralogy of the Asuka 87 and 88 eucrites and crustal evolution of the HED parent body

Mineralogical study of three apparently crystalline eucrites, Asuka (A)-87272,A-881388 and A-881394 revealed that their textures are not primary crystallization products from a magma. A-87272 is a monomict breccia, but the finegrained matrix is recrystallized to a granulitic texture with fine, rounded pyroxene crystals set in a plagioclase matrix. Large fragments of pyroxene are inverted to orthopyroxene with coarse exsolution lamellae on (001) and fine ones on (100). A-881388 contains a large, rounded opaque grain with a tail, and with an ilmenite-chromite-troilite-metal assemblage in fine-grained granulitic silicates, suggesting recrystallization. A-881394 is coarser grained than A-881388 and contains more magnesian pyroxene as in cumulate eucrites, but the plagioclase composition is extremely calcic (An 98) and the grains are composed with a few rounded grains. The A-881394 chromite, showing a pokilitic texture with rounded plagioclase and minor pyroxene, suggests a metamorphic texture. Our present interpretation for a common formation process among these eucrites is that despite their crystalline texture, they might have experienced extensive metamorphism after the initial crystallization in the early history of the crustal evolution

Metamorphic transformations of opaque minerals in some eucrites

Eucrites have undergone varying degrees of metamorphism on their parent body. We investigated mineralogical constraint on the eucrite metamorphism, especially from opaque mineralogy. Three eucrites with distinct degrees of metamorphism were studied : Y-75011,84 is the least equilibrated basaltic clast, Juvinas shows complex histories of shock and thermal metamorphism, and A-881388 is an extensively annealed and unbrecciated. Three eucrites with different metamorphic histories show distinct opaque mineralogy. In Y-75011,84,ilmenite and troilite are found crystallized in the mesostasis and opaque precipitates within pyroxenes are barely recognized. Juvinas has complicated texture, consisting of a variety of lithologies : Minute precipitates within pyroxene area and recrystallized mesostases. In A-881388,during extensive prolonged annealing episode, opaque phases, such as ilmenite, troilite, and chromite are almost completely separated from silicate phases and segregated, resulting in a formation of opaque nodules. Several geothermometers, experimental results and the textural appearance of A-881388 suggest that it might have slowly cooled from near 1000-1050℃ to ∿800℃ during a prolonged annealing episode. While chromite is not observed in Y-75011,84,Juvinas and A-881388 contain chromite in recrystallized mesostases and in an nodule respectively. This implies that chromite could be a metamorphic product

Effects of Interval Time of the Epley Manoeuvre

Objective: The Epley maneuver (EM) has an immediate effect: rapid reduction of positional nystagmus. Benign paroxysmal positional vertigo (BPPV) causes BPPV fatigue, which constitutes fatigability of positional nystagmus and vertigo with repeated performance of the Dix-Hallpike test; notably, BPPV fatigability becomes ineffective over time. We hypothesized that the immediate effect of the EM is caused by BPPV fatigue. Therefore, we suspected that performance of the EM with intervals between head positions would worsen the immediate reduction of positional nystagmus in patients with BPPV, because BPPV fatigability would become ineffective during performance of this therapy. Methods: Forty patients with newly diagnosed BPPV were randomly assigned to the following two groups; one group performed the EM without intervals between positions (group A), and the other group performed the EM with 3 min intervals between positions (group B). The primary outcome measure was the ratio of maximum slow-phase eye velocity (MSPEV) of positional nystagmus soon after the EM, compared with that measured before the EM. Secondary outcome included whether a 30 min interval after the EM enabled recovery of MSPEV of positional nystagmus to the original value. This study followed the CONSORT 2010 reporting standards. Results: In both groups A and B, the immediate effect of the EM could be observed, because MSPEV during the second Dix-Hallpike test was significantly smaller than MSPEV during the first Dix-Hallpike test (p < 0.0001 in group A, p < 0.0001 in group B). The primary outcome measure was larger in group B than in group A (p = 0.0029). The immediate effect faded 30 min later (secondary outcome). Conclusions: This study showed that the EM had an immediate effect both with and without interval time in each head position of the EM. Because setting interval time in each head position of the EM reduced the immediate effect of the EM, interval time during the EM adds less benefit. This finding can reduce the effort exerted by doctors, as well as the discomfort experienced by patients with pc-BPPV, during EM. However, this immediate effect may be caused by BPPV fatigue, and may fade rapidly

Application of nanofiltration processes to fluoride removal from groundwaters in the Chiang Mai Basin

The highly concentrated fluoride in groundwater has been observed in the confined aquifers of the alluvial sediments in the Chiang Mai Basin. Nanofiltration process was applied to the control of fluoride exposure to the local residents, who have suffered from serious dental and osteal fluorosis. The membrane plants used polyamide nanofilters, which were found to have different fluoride removal rates depending on pH of feed waters. Although fluoride removal rates were high at neutral to basic pH, calcium carbonate scale on the membrane surface was estimated to be the major problem in membrane fouling. Optimum combination of pretreatment in the membrane plant was evaluated through the investigation on the groundwater quality and the operational conditions

ナトリウム イゾンセイ リンサン トランスポーター IIa ガタ NaPi-IIa ノ フクコウジョウセン ホルモン PHT ニヨル チョウセツ キコウ

Parathyroid hormone （PTH） is the most potent and important regulator of the type II a sodium-dependent phosphate transporter （NaPi-IIa）, which plays a key role in renal phosphate reabsorption and maintaining inorganic phosphate homeostasis. PTH inhibits the NaPi-IIa activity by stimulation of translocation from the apical plasma membrane to the intracellular organelle. In this paper, we investigated the mechanism of the translo-cation of NaPi-IIa from the apical plasma membrane by cell fractionation analysis using OK-N２ cells that stably express human NaPi-IIa established from opossum kidney cells （OK-P cells）. NaPi-IIa was mostly localized in the caveolae-like membrane domains of the plasma membrane in OK-N２ cells We also clarified that PTH activated both PKA and PKC, and these kinases markedly increased the phosphorylation of their ８０kDa and ２５０kDa substrates on the caveolae-like membrane domains ; we identified ezrin as a candidate protein for the ８０kDa substrate. We conclude that caveolae-like membrane domains play an important role in the targeting, translocation, and signal compartmentalization for the translocational regulation of NaPi-IIa in renal proximal tubular cells