Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry Cu deposits. Porphyry Cu deposits are typically oxidized, but when and how porphyry magmas gain their high oxygen ...fugacity signatures, and how oxygen fugacity controls porphyry mineralization, remains obscure. To trace the origin of the high oxygen fugacity in porphyry Cu deposits, we determined trace element compositions and U-Pb ages of magmatic and inherited zircon from Dexing porphyry Cu deposit, calculated Ce4+/Ce3+ of zircons and estimated the oxygen fugacity of their parental magmas. The Ce4+/Ce3+ ratios of Middle Jurassic (∼170Ma) magmatic zircons are high (550 on average), whereas the Ce4+/Ce3+ ratios of inherited zircons (200–880Ma) are much lower (263 on average). The relationship suggests that the Dexing porphyry magma was highly oxidized when the Jurassic magmatic zircons crystallized (estimated fO2: ΔFMQ+0.7 (±1.3) – ΔFMQ+1.9 (±1.3)), which cannot be attributed to partial melting of the Neoproterozoic arc crust (estimated fO2: ΔFMQ−2.4 (±1.1) – ΔFMQ+0.7 (±1.2)) as proposed previously. Instead, the high fO2 (ΔFMQ+1.5) of these magmas is a primary feature of the latest magmatism. Sulfate rather than sulfide is the dominant species at fO2>ΔFMQ+1.5. In general, the behavior of Cu and other chalcophile elements is controlled by sulfide, while the sulfur speciation is controlled by oxygen fugacity. Previous modeling results show that partial melting of mantle peridotite under high oxygen fugacity (even at >ΔFMQ+1.5) cannot form Cu-rich magmas, which plausibly explains the lack of porphyry Cu deposits in normal arc rocks. This is because mantle peridotite has low Cu and S contents. Our modeling shows that partial melting of subducted oceanic crust, under oxygen fugacities higher than ΔFMQ+1.5, is favorable for producing primary magmas with Cu contents sufficiently high for porphyry mineralization, which plausibly explains the close relationship between porphyry Cu deposits and oxidized magmas with adakitic affinities.
Zhang, C., 2020. Binocular vision navigation method of marine garbage cleaning robot in unknown dynamic scene. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in ...Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 864–867. Coconut Creek (Florida), ISSN 0749-0208. When the current method was adopted for the vision navigation of marine garbage cleaning robot, the results of target garbage location were quite different from actual results, and the time of controlling the robot to the target location was too long, resulting in low positioning accuracy and poor path planning effect. Therefore, a method of binocular vision navigation of marine garbage cleaning robot in unknown dynamic scene was put forward. The camera was calibrated to extract the feature points in target image. Moreover, the moving path of robot was planned by dynamic obstacle avoidance algorithm based on escape velocity. In the unknown dynamic scene, the navigation of marine garbage cleaning robot was realized. Experimental results show that the proposed method has high positioning accuracy and good path planning effect.
Bismuth oxyhalide (BiOX, X = Cl, Br, I) nanomaterials have attracted enormous attention because their unique layered structure and nano‐size effect endows them with fascinating physicochemical ...properties and wide application potential. However, synthesis of ultrasmall BiOX nanocrystals with sizes down to sub‐10 nm remains a considerable challenge and the investigation of such ultrasmall BiOX nanocrystals in alkali‐metal ion batteries have not yet been explored so far. The fabrication of ultrasmall BiOX nanocrystals with an average size of 6 nm on reduced graphene oxide by a versatile nanoconfinement strategy is reported here. The obtained ultrasmall BiOCl nanocrystals‐based monolithic composites are evaluated as free‐standing anodes for potassium‐ion batteries (PIBs) and exhibit the highest reversible capacity of 521 mAh g−1 at 0.05 A g−1 among all reported Bi‐based PIB anodes and ultrahigh volumetric capacity of 1148 mAh cm‐3, along with excellent rate capability (205 mAh g−1 at 5 A g−1 ) and extraordinary cycling stability with 94.7% capacity retention after 3000 cycles. More importantly, a fully reversible potassium storage mechanism of BiOCl (BiOCl ↔ Bi ↔ K3Bi) induced by the ultrasmall nano‐size effect is revealed for the first time by detailed characterizations, providing new fundamental insights for boosting the electrochemical performance of nanostructured materials.
A general nanoconfinement strategy is demonstrated to fabricate ultrasmall bismuth oxyhalide nanocrystals. Endowed by the ultrasmall nanosize effect, the sub‐10 nm bismuth oxychloride nanocrystal deliver the highest potassium‐ion storage capacity reported among all bismuth‐based materials and achieve fully reversible potassium‐ion storage mechanism, which has never been realized thus far.
N6-Methyladenosine (m6A) RNA methylation plays important roles during development in different species. However, knowledge of m6A RNA methylation in monocots remains limited. In this study, we ...reported that OsFIP and OsMTA2 are the components of m6A RNA methyltransferase complex in rice and uncovered a previously unknown function of m6A RNA methylation in regulation of plant sporogenesis. Importantly, OsFIP is essential for rice male gametogenesis. Knocking out of OsFIP results in early degeneration of microspores at the vacuolated pollen stage and simultaneously causes abnormal meiosis in prophase I. We further analyzed the profile of rice m6A modification during sporogenesis in both WT and OsFIP loss-of-function plants, and identified a rice panicle specific m6A modification motif "UGWAMH". Interestingly, we found that OsFIP directly mediates the m6A methylation of a set of threonine protease and NTPase mRNAs and is essential for their expression and/or splicing, which in turn regulates the progress of sporogenesis. Our findings revealed for the first time that OsFIP plays an indispensable role in plant early sporogenesis. This study also provides evidence for the different functions of the m6A RNA methyltransferase complex between rice and Arabidopsis.
Plant laccase (LAC) enzymes belong to the blue copper oxidase family and polymerize monolignols into lignin. Recent studies have established the involvement of microRNAs in this process; however, ...physiological functions and regulation of plant laccases remain poorly understood. Here, we show that a laccase gene, LAC4, regulated by a microRNA, miR397b, controls both lignin biosynthesis and seed yield in Arabidopsis. In transgenic plants, overexpression of miR397b (OXmiR397b) reduced lignin deposition. The secondary wall thickness of vessels and the fibres was reduced in the OXmiR397b line, and both syringyl and guaiacyl subunits are decreased, leading to weakening of vascular tissues. In contrast, overexpression of miR397b‐resistant laccase mRNA results in an opposite phenotype. Plants overexpressing miR397b develop more than two inflorescence shoots and have an increased silique number and silique length, resulting in higher seed numbers. In addition, enlarged seeds and more seeds are formed in these miR397b overexpression plants. The study suggests that miR397‐mediated development via regulating laccase genes might be a common mechanism in flowering plants and that the modulation of laccase by miR397 may be potential for engineering plant biomass production with less lignin.
Exosomes have been considered as novel and potent vehicles of intercellular communication, instead of "cell dust". Exosomes are consistent with anucleate cells, and organelles with lipid bilayer ...consisting of the proteins and abundant lipid, enhancing their "rigidity" and "flexibility". Neighboring cells or distant cells are capable of exchanging genetic or metabolic information via exosomes binding to recipient cell and releasing bioactive molecules, such as lipids, proteins, and nucleic acids. Of note, exosomes exert the remarkable effects on lipid metabolism, including the synthesis, transportation and degradation of the lipid. The disorder of lipid metabolism mediated by exosomes leads to the occurrence and progression of diseases, such as atherosclerosis, cancer, non-alcoholic fatty liver disease (NAFLD), obesity and Alzheimer's diseases and so on. More importantly, lipid metabolism can also affect the production and secretion of exosomes, as well as interactions with the recipient cells. Therefore, exosomes may be applied as effective targets for diagnosis and treatment of diseases. Video abstract.
Web surveys can be programmed to capture a variety of paradata regarding how respondents answer questions. These paradata provide great opportunities for researchers to assess response quality, ...specifically whether respondents engage in satisficing – not spending enough effort to provide accurate responses. In particular, speeding (i.e., giving answers very quickly) has increasingly been used as an indicator for satisficing and low response quality. However, few studies have examined whether speeding actually leads to compromised response quality. To address this gap in the literature, the current study investigates speeding behaviors among Web respondents from a probability-based panel. We first identify and characterize respondents who speed more frequently than others over the entire questionnaire. To explore the impact of speeding on response quality, we then examine whether respondents who speed more frequently also straightline in more grid questions. The results show that the tendency to speed is related to several respondent characteristics, particularly age (younger respondents are more likely to speed). This study also reveals that more speeding seems to be universally related to more straightlining, and this relationship is particularly strong among the less educated respondents.
The cereal endosperm is a major factor determining seed size and shape. However, the molecular mechanisms of endosperm development are not fully understood. Long noncoding RNAs (lncRNAs) function in ...various biological processes. Here we show a lncRNA, MISSEN, that plays an essential role in early endosperm development in rice (Oryza sativa). MISSEN is a parent-of-origin lncRNA expressed in endosperm, and negatively regulates endosperm development, leading to a prominent dent and bulge in the seed. Mechanistically, MISSEN functions through hijacking a helicase family protein (HeFP) to regulate tubulin function during endosperm nucleus division and endosperm cellularization, resulting in abnormal cytoskeletal polymerization. Finally, we revealed that the expression of MISSEN is inhibited by histone H3 lysine 27 trimethylation (H3K27me3) modification after pollination. Therefore, MISSEN is the first lncRNA identified as a regulator in endosperm development, highlighting the potential applications in rice breeding.
Nanoconfinement Synthesis
In article number 2201352, Yuxi Xu and co‐workers develop a general nanoconfinement strategy to fabricate ultrasmall bismuth oxyhalide nanocrystals with size‐induced full ...reversible potassium‐ion storage mechanism and ultrahigh electrochemical capacity.
Porphyry deposits and oxidized magmas Sun, Weidong; Huang, Rui-fang; Li, He ...
Ore geology reviews,
March 2015, 2015-03-00, Letnik:
65
Journal Article
Recenzirano
Porphyry deposits supply most of the world's Cu and Mo resources. Over 90% of the porphyry deposits are found at convergent margins, especially above active subduction zones, with much fewer ...occurrences at post-collisional or other tectonic settings. Porphyry Cu–(Mo)–(Au) deposits are essentially magmatic–hydrothermal systems, which are generally initiated by injection of oxidized magmas saturated with metal-rich aqueous fluids, i.e., the parental magmas need to be water rich and oxidized with most of the sulfur appearing as sulfate in the magma. Sulfur is the most important geosolvent that controls the behavior of Cu and other chalcophile elements, due to high partition coefficients of chalcophile elements between sulfide and silicate melts. Small amount of residual sulfides can hold a large amount of Cu. Therefore, it is essential to eliminate residual sulfides to get high Cu contents in magmas for the formation of porphyry deposits. Sulfate (SO42−) is over 10 times more soluble than sulfide (S2−), and thus the solubility of sulfur depends strongly on sulfur speciation, which in turn depends on oxygen fugacities. The magic number of oxygen fugacity is log fO2>FMQ+2 (i.e., ΔFMQ+2), where FMQ is the fayalite–magnetite–quartz oxygen buffer. Most of the sulfur in magmas is present as sulfate at oxygen fugacities higher than ΔFMQ+2. Correspondingly, the solubility of sulfur increases from ~1000ppm up to >1wt.%. Oxidation promotes the destruction of sulfides in the magma source, and thereby increases initial chalcophile element concentrations, forming sulfur-undersaturated magmas that can further assimilate sulfides during ascent. Copper, Mo and Au act as incompatible elements in sulfide undersaturated magmas, leading to high chalcophile element concentrations in evolved magmas. The final porphyry mineralization is controlled by sulfate reduction, which is usually initiated by magnetite crystallization, accompanied by decreasing pH and correspondingly increasing oxidation potential of sulfate. Hematite forms once sulfate reduction lowers the pH sufficiently, driving the oxidation potential of sulfate up to the hematite–magnetite oxygen fugacity (HM) buffer, which is ~ΔFMQ+4. Given that ferrous iron is the most important reductant that is responsible for sulfate reduction during porphyry mineralization, the highest oxygen fugacity favorable for porphyry mineralization is the HM buffer. In addition to the oxidation of ferrous iron during the crystallization of magnetite and hematite, reducing wallrock may also contribute to sulfate reduction and mineralization. Nevertheless, porphyry deposits are usually mineralized in the whole upper portion of the pluton, whereas interactions with country rocks are generally restricted at the interface, therefore assimilation of reducing sediments is not likely to be a decisive controlling process. Degassing of oxidized gases has also been proposed as a major process that is responsible for sulfate reduction. Degassing, however, is not likely to be a main process in porphyry mineralization that occurs at 2–4km depths in the upper crust. Sulfide formed during sulfate reduction is efficiently scavenged by aqueous fluids, which transports metals to shallower depths, i.e., the top of the porphyry and superjacent wallrock. According to traditional views, sulfide saturation and segregation during magma evolution is not favorable for the formation of porphyry Cu±Au±Mo deposits. This is the main difference between porphyry deposits and Ni–Cu sulfide deposits. Nevertheless, in places with thick sections of reducing sediments, e.g., the western North America, sulfide saturation and segregation may occur during evolution of the magma, forming Cu-rich cumulates at the base of plutons. These Cu-rich sulfides may evolve into porphyry mineralization or even control the ore-forming process. Their contribution depends heavily on subsequent oxidation, i.e., a major contribution can be expected only when the sulfide cumulates are oxidized to sulfate, liberating the chalcophile elements. Sulfate reduction and ferrous Fe oxidation form H+, which dramatically lowers the pH values of ore-forming fluids and causes pervasive alteration zones in porphyry Cu deposits. The amount of H+ released during mineralization and the alkali content in the porphyry together control the intensity of alterations. In principle, H2 and methane form during the final mineralization process of porphyry deposits, but are mostly oxidized by ferric Fe during subsequent processes. Some of the reduced gases, however, may survive the highly oxidizing environment to escape from the system, or even to get trapped in fluid inclusions. Therefore, small amount of reduced gases in fluid inclusions cannot argue against the oxidized feature of the magmas. Reduced magmas are not favorable for porphyry mineralization. Reduced porphyry deposits so far reported are just mineralization that has either been reduced in host rock away from the causative porphyry or through assimilation of reducing components during emplacement.
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