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The predominant types of high-grade iron deposits in China include skarn, sedimentary metamorphic (banded iron-formation, BIF-type), continental/submarine volcanic-hosted and magmatic Fe-Ti-V oxide deposits. Based on a comprehensive review of current studies on these deposits, this paper suggests that the oxygen concentration in atmosphere played an important role for the formation of BIFs, whereas the tectonic setting and deep magmatic differentiation processes are more important for the other types. Notably, both high temperature and high pressure experiments and melt inclusion studies indicate that during the differentiation, high temperature magmas could develop iron-rich magma via liquid immiscibility but not pure oxide melt (“iron ore magma”). Fe-P melt could be generated directly by liquid immiscibility under hydrous and oxidized condition. The formation of high-grade iron deposits is mostly associated with the processes related to multiple stages of superimposition, e.g., desiliconization and iron enrichment, removal of impurity, and remobilization and re-precipitation of iron. According to the temporal evolution, the high-grade iron deposit could be divided into multi-episode superimposition type (temporally discontinuous mineralization) and multi-stage superimposition type (temporally continuous mineralization). The former is represented by the sedimentary metamorphic iron deposit, and the latter includes those related to magmatic-hydrothermal fluids (e.g., skarn, volcanic-hosted and magmatic types).

Although the involvement of hydrous fluids has been widely invoked in formation of podiform chromitites in ophiolites, there is lack of natural evidence to signify the role and mechanism of fluids. In this study, a new model for the genesis of podiform chromitite is proposed on basis of revisits of comprehensive petrological, mineralogical and geochemical results of the well-preserved Kızıldağ ophiolite and the well-characterized Luobusa chromite deposit. In this model, ascending magmas intruding oceanic lithospheric mantle would presumably form a series of small magma chambers continuously connected by conduits. Tiny chromite nuclei would collect fluids dispersed in such magmas to form nascent droplets. They tend to float upward in the magma chamber and would be easily transported upward by flowing magmas. Chromite-rich droplets would be enlarged via coalescence of dispersed droplets during mingling and circulation in the magma chamber and/or transport in magma conduits. Crystallization of the chromite-rich liquid droplets would proceed from the margin of the droplet inward, leaving liquid entrapped within grains as precursor of mineral inclusions. With preferential upward transportation, immiscible chromite-rich liquids would coalesce to a large pool in a magma chamber. Large volumes of chromite would crystallize in situ , forming podiform chromitite and resulting in fluid enrichment in the chamber. The fluids would penetrate and compositionally modify ambient dunite and harzburgite, leading to significant fractionations of elemental and isotopic compositions between melts and fluids from which dunite and chromitite respectively formed. Therefore, fluid immiscibility during basaltic magma ascent plays a vital role in chromitite formation.

Eighty years ago, it was proposed that solid hydrogen would become metallic at sufficiently high density. Despite numerous investigations, this transition has not yet been experimentally observed. More recently, there has been much interest in the analog of this predicted metallic transition in the dense liquid, due to its relevance to planetary science. Here, we show direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium. Experimental determination of the location of this transition provides a much-needed benchmark for theory and may constrain the region of hydrogen-helium immiscibility and the boundary-layer pressure in standard models of the internal structure of gas-giant planets.

The carbonatites of Brava Island, Cape Verde hot spot, allow to investigate whether they represent small mantle melt fractions or form through extreme fractionation and/or liquid immiscibility from CO 2 -bearing silicate magmas. The intrusive carbonatites on Brava Island are part of a strongly silica-undersaturated pyroxenite, ijolite, nephelinite, nepheline syenite, combeite–foiditite, carbonatite series. The major and trace element composition of this suite is reproduced by a model fractionating olivine, clinopyroxene, perovskite, biotite, apatite, titanite, sodalite and FeTi oxides, all present as phenocrysts in the rocks corresponding to their fractionation interval. Fractionation of ~90 wt% crystals reproduces the observed geochemical trend from the least evolved ultramafic dikes (bulk X Mg  = 0.64) to syenitic compositions. The modelled fractional crystallization leads to alkali enrichment, driving the melt into the carbonatite–silicate miscibility gap. An initial CO 2 content of 4000 ppm is sufficient to saturate in CO 2 at the point where the rock record suggests continuing unmixing carbonatites from nephelinites to nepheline syenites after 61 wt% fractionation. Such immiscibility is also manifested in carbonatite and silicate domains on a hand-specimen scale. Furthermore, almost identical primary clinopyroxene, biotite and carbonate compositions from carbonatites and nephelinites to nepheline syenites substantiate their conjugate character and our unmixing model. The modelled carbonatite compositions correspond to the natural ones except for their much higher alkali contents. The alkali-poor character of the carbonatites on Brava and elsewhere is likely a consequence of the release of alkali-rich CO 2  + H 2 O fluids during final crystallization, which cause fenitization in adjacent rocks. We propose a general model for carbonatite generation during alkaline magmatism, where the fractionation of heavily Si-undersaturated, alkaline parent melts results in alkali and CO 2 enrichment in the evolving melt, ultimately leading to immiscibility between carbonatites and evolved Si-undersaturated alkaline melts. Early saturation in feldspathoids or feldspars would limit alkali enrichment preventing the formation of carbonatites. The complete and continuous fractionation line from almost primitive melts to syenitic compositions on Brava underlines the possibly important role of intrusives for hot spot volcanism.

This study investigated the Boam mine area, a prominent Li-pegmatite deposits located in South Korea, using Li-bearing micas to determine the magmatic–aqueous transition involved in rare-element pegmatite formation. Muscovite–lepidolite series micas from the layered pegmatite exhibited six textures, classified into three stages (early, intermediate, and late) based on compositions of major and trace elements. The substitution mechanisms of muscovite–lepidolite series micas follow lithium fixation (Si ↔ Li + Al) and phengitic substitution (Aliv + 2Alvi ↔ Li + (Fe2+, Mg2+, Mn2+) + Si) vectors. Early-stage micas displayed a large grain size due to rapid crystal growth due from low undercooling. Diffusional zonation of these micas with the higher Nb–Ta and lower Li concentrations compared with later-stage lepidolite indicate a lower degree of fractionation. These features suggest a silicic melt origin for early-stage micas. Intermediate-stage micas are distinctly separated from the early-stage type and feature erratic boundaries with higher Li composition. B enrichment reduced the melt viscosity and increased the H2O solubility, resulting in an increase in growth rate and retardation of mineralization. The inhibition of HFSE partitioning by B lead to a lower Nb–Ta concentration than the silicic melt, suggesting the existence of an aqueous melt. Fine-grained late-stage mica coexists with microcrystalline quartz, and is characterized by Cs enrichment and Nb–Ta depletion that exclusively occur in flux-rich aqueous fluids. Non-Rayleigh behavior of K-Rb-Cs indicates a deviation from fractional crystallization unlike melt phases, suggesting an aqueous fluid origin for late-stage micas. Consequently, the formation of Li-pegmatite in the deposit was predominantly controlled by the immiscibility of silicic melt–aqueous melt–aqueous fluid and fractional crystallization within each medium.

We present two binary lipid–sterol membrane systems that exhibit fluid–fluid coexistence. Partial phase diagrams of binary mixtures of dimyristoylphosphatidylcholine with 25-hydroxyxholesterol and 27-hydroxycholesterol, determined from small-angle X-ray scattering and fluorescence microscopy studies, show closed-loop fluid–fluid immiscibility gaps, with the appearance of a single fluid phase both at higher and lower temperatures. Computer simulations suggest that this unusual phase behavior results from the ability of these oxysterol molecules to take different orientations in the membrane depending on the temperature.

N-doping plays an irreplaceable role in controlling the electron concentration of organic semiconductors thus to improve performance of organic semiconductor devices. However, compared with many mature p-doping methods, n-doping of organic semiconductor is still of challenges. In particular, dopant stability/processability, counterion-semiconductor immiscibility and doping induced microstructure non-uniformity have restricted the application of n-doping in high-performance devices. Here, we report a computer-assisted screening approach to rationally design of a triaminomethane-type dopant, which exhibit extremely high stability and strong hydride donating property due to its thermally activated doping mechanism. This triaminomethane derivative shows excellent counterion-semiconductor miscibility (counter cations stay with the polymer side chains), high doping efficiency and uniformity. By using triaminomethane, we realize a record n-type conductivity of up to 21 S cm −1 and power factors as high as 51 μW m −1  K −2 even in films with thicknesses over 10 μm, and we demonstrate the first reported all-polymer thermoelectric generator. Realizing efficient n-doping in organic thermoelectrics remains a challenge due to dopant-semiconductor immiscibility, poor dopant stability and low doping efficiency. Here, the authors use computer-assisted screening to develop n-dopants for thermoelectric polymers that show record power factors.

Liquid immiscibility has become the preferred mode of genesis for the carbonatite rocks, which commonly, but not exclusively, accompany silicate rocks in alkaline-rock complexes. This concept has been universally based on the presumption that nephelinitic and phonolitic magmas can evolve to a stage where two conjugate immiscible liquids separate. It is assumed that these two liquids separate quickly, or even instantaneously, into discrete bodies of magma capable of being intruded or extruded with subsequent independent crystallization. Supporting evidence generally given is: alleged consanguinity as discrete occurrence of the two rock types; similarity of radiogenic isotope ratios; trace element contents similar to those predicted from experimentally derived partition coefficients. We do not accept that a general case for liquid immiscibility has been demonstrated; although we do accept that silicate and carbonate liquids are inherently immiscible, we maintain that they are not conjugate in a petrogenetic context. We have reviewed and critically examined the experimental data purporting to establish liquid immiscibility and find that when applied to natural rocks, they are based on inappropriate experimental designs, which are not relevant to the genesis of calcite or dolomite carbonatites, although they might have some relevance to Oldoinyo Lengai nyerereite–gregoryite lavas. The design of these experiments guarantees immiscibility and ensures that the carbonate liquids formed will be calcitic or sodium-rich. We dispute the validity of comparing the trace element contents of natural rocks, which in many instances do not represent liquid compositions, to experimentally determine partition coefficients. We consider that experimental design inadequacies, principally assuming but not proving, that the liquids involved are conjugate, indicate that these coefficients are merely an expression of the preference of certain elements for particular liquids, regardless of how the liquids formed. Proof of consanguinity in alkaline complexes requires more accurate age determinations on the relevant rock types than has generally been the case, and in most complexes, consanguinity can be discounted. We dispute the contention that melt inclusions represent parental melts, although they might elucidate the character of magmas undergoing fractional crystallization from magmatic to carbothermal stages. Radiogenic isotope data are shown to be too widely variable to support a case for liquid immiscibility. We address the contention that calcite cannot crystallize from a dolomitic liquid formed by direct mantle melting, and must therefore have crystallized from a calcite carbonate liquid generated by liquid immiscibility, and demonstrate that it is an unsupported hypothesis as calcite can readily crystallize from dolomitic liquids. We observe that, because immiscible dolomite liquids have never been produced experimentally, the liquid immiscibility proposition could at best be applied only to calcite carbonatites, thus leaving unexplained the large number of dolomite carbonatites and those of either type, which are not accompanied by alkaline silicate rocks. The assumed bimodality of alkaline-rock carbonatite complexes is considered to be fallacious and no actual geological or petrographic evidence for immiscibility processes is evident in these complexes. Several examples of alkaline rock carbonatite complexes for which immiscibility has been proposed are evaluated critically and shown to fail in attempts to establish them as exemplifying immiscibility. We conclude that no actual geological or experimental data exist to establish liquid immiscibility being involved in the genesis of calcite or dolomite carbonatite-forming magmas.

Endogenous biomolecular condensates, composed of a multitude of proteins and RNAs, can organize into multiphasic structures with compositionally distinct phases. This multiphasic organization is generally understood to be critical for facilitating their proper biological function. However, the biophysical principles driving multiphase formation are not completely understood. Here we use in vivo condensate reconstitution experiments and coarse-grained molecular simulations to investigate how oligomerization and sequence interactions modulate multiphase organization in biomolecular condensates. We demonstrate that increasing the oligomerization state of an intrinsically disordered protein results in enhanced immiscibility and multiphase formation. Interestingly, we find that oligomerization tunes the miscibility of intrinsically disordered proteins in an asymmetric manner, with the effect being more pronounced when the intrinsically disordered protein, exhibiting stronger homotypic interactions, is oligomerized. Our findings suggest that oligomerization is a flexible biophysical mechanism that cells can exploit to tune the internal organization of biomolecular condensates and their associated biological functions. The biomolecular principles underlying the formation of multiphasic condensates have been difficult to elucidate owing to a paucity of tools, especially within living cells. In this work synthetic orthogonal protein scaffolds alongside molecular simulations are used to highlight how the oligomerization of disordered proteins can asymmetrically drive miscibility–immiscibility transitions.

Understanding the mixing behaviour of elements in a multielement material is important to control its structure and property. When the size of a multielement material is decreased to the nanoscale, the miscibility of elements in the nanomaterial often changes from its bulk counterpart. However, there is a lack of comprehensive and quantitative experimental insight into this process. Here we explored how the miscibility of Au and Rh evolves in nanoparticles of sizes varying from 4 to 1 nm and composition changing from 15% Au to 85% Au. We found that the two immiscible elements exhibit a phase-separation-to-alloy transition in nanoparticles with decreased size and become completely miscible in sub-2 nm particles across the entire compositional range. Quantitative electron microscopy analysis and theoretical calculations were used to show that the observed immiscibility-to-miscibility transition is dictated by particle size, composition and possible surface adsorbates present under the synthesis conditions. Nanoparticles containing immiscible elements can be synthesized under certain experimental conditions.