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Xenopus oocyte cell extracts administered to Xenopus egg extracts block the Xenopus sperm nuclei and double-stranded plasmid DNA template replication. The immature oocytes contain molecules that negatively control the replication of chromosomal DNA. Negative factors decrease during the maturation of the oocytes. The inhibitory process is not caused due to template DNA degradation or suppression of chain elongation by the oocytes.

Abstract In this work, a new strategy was proposed to improve the foamability of poly(aryl ether ketone) (PAEK) based on novel long-chain branched PAEK (LCB-PAEK). To improve the resin melt strength, the amorphous LCB-PAEK was fabricated via a simple ternary copolymerization of phenolphthalein, 4,4′-difluorobenzophenone, and 1,1,1-tris(4-hydroxyphenyl)ethane. To regulate the extent of reaction and avoid crosslinking, 4-fluorobenzophenone was introduced as the end-capping reagent. The presence of long-chain branches were proved by gel permeation chromatography and rheological characteristics, including storage modulus and tensile viscosity. Afterwards, the prepared LCB-PAEK samples were foamed using supercritical carbon dioxide (ScCO 2) as the blowing agent. The influence of branching content on foaming results was investigated in detail, and significant improvement in foamability was observed. By regulating the foaming parameters, the highest expansion ratio of 27.5 was achieved, which was almost ninefold higher than that of linear PAEK. In addition, the good mechanical properties indicated the promising applications of LCB-PAEK foams as high-performance structural foam. Graphical abstract Novel long-chain branched poly(aryl ether ketone) significantly improved the foamability of PAEK. Image 102347 Highlights • Novel long-chain branched PAEK was designed and synthesized for high-expanded PAEK foam. • Expansion ratio of 27.5 is the highest one for PAEK foams reported so far. • Low density PAEK foams with certain mechanical properties were firstly reported. • This work Provide a strategy for design other high-performance foams, such PES, PAR, with high-expansion ratio. [ABSTRACT FROM AUTHOR]

Abstract: Experiments on uniaxial and triaxial rock mechanics and rock acoustic emissions have been conducted for research on the impact of rock anisotropy on the development of the fractures of different directions by taking as an example the ultra-low-permeability sandstone reservoir in the Upper Triassic Yanchang Formation within the Ordos Basin. The experimental results prove the existence of anisotropy of the rock mechanical property in the different directions on the plane, which is the chief reason for the production of impacts on the development of different assemblages of fractures in the geological periods. The rock anisotropy usually restricts the development of one assemblage of conjugate shear fractures. The fractures in the Yanchang Formation within the Ordos Basin are mainly shear fractures that formed under two tectonic actions. Theoretically, here, four assemblages of shear fractures should have developed, but due to the effect of a strong rock anisotropy, in each period one assemblage of fractures chiefly developed. Thus, two assemblages of fractures are usually developed in every part at present. [Copyright &y& Elsevier]

Gallstones were classified in to 5 types (pure cholesterol stone, mixed cholesterol stone, calcium bilirubinate stone, black pigment stone and combination stone). In subgroup of gallstones, the proportion of black pigments stone was increased (34.0% to 45.5%), but that of calcium bilirubinate stone was decreased (20.7% to 5.3%). On the aspect of patients'area, calcium bilirubinate stone decreased in both urban and rural area, black pigment stone was increased in both urban and rural area. [Extracted from the article]

Basaltic volcanism on the Moon produced low- and high-Ti mare basalt suites that are also distinct with respect to their iron, titanium, and magnesium isotopic compositions. Here, the equilibrium fractionation of Fe and Ti isotopes between ilmenite and melt was experimentally investigated in order to evaluate the role of ilmenite in generating the isotopic compositional variability among the lunar mare basalts. Ilmenite crystallization experiments were conducted using two bulk compositions: an ilmenite-saturated basaltic andesite and an ilmenite-saturated Apollo 14 black glass, and the Fe and Ti isotopic compositions of the experimental ilmenites and glass (quenched melt) were analyzed using solution MC-ICPMS after hand-picking. Additionally, Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements on synthetic ilmenite were conducted and compared to previous NRIXS measurements on synthetic lunar glasses in order to derive temperature-dependent equilibrium ilmenite-melt Fe isotopic fractionations. Experimentally determined ilmenite-melt fractionations were then incorporated into a lunar magma ocean crystallization model that tracks the major element and isotopic compositional evolution of lunar magma ocean cumulates and residual liquid. There is good agreement between the Fe equilibrium isotopic fractionation measured by NRIXS and the laboratory equilibration experiments, and we find that the isotopic fractionation is sensitive to ilmenite compositional differences (0 vs. 10% Fe3+). Further, the light Ti isotopic composition of ilmenite relative to the melt (Δ 49 Ti = ilmenite-melt − 0.09 ± 0.03 ‰ at 1100 ∘C) is consistent with the higher coordination of Ti in ilmenite relative to melts and results of previous studies. The modeled Ti isotopic compositions for lunar magma ocean cumulates display Ti isotopic variability sufficient to explain the low- and high-Ti mare basalt sources. However, the difference in Fe isotopic composition between the low- and high-Ti mare basalts cannot be attributed solely to ilmenite fractionation. Instead, Fe isotopic fractionation by additional products of lunar magma ocean crystallization, such as clinopyroxene, is required to generate the inferred Fe and Mg isotopic variability in the lunar mantle. Alternatively, the Fe and Mg isotopic compositions of the lunar mare basalts may indicate Fe-Mg interdiffusion has occurred in the Ti-rich component of the mare basalt source regions via reaction between ilmenite cumulates and the olivine- and pyroxene-rich lunar mantle. [ABSTRACT FROM AUTHOR]

The tight oil sandstone reservoir of the Upper Triassic Yanchang Formation is one of the main targets for hydrocarbon exploration in the Ordos Basin, China. Sandstones of the Upper Triassic Yanchang Formation within lacustrine deep-water gravity-flow deposits are characterized by ultralow porosity, ultralow permeability, and complex diagenetic alterations and sedimentary lithofacies. However, the diagenetic alterations and their controls on the reservoir quality of the Chang 6 tight sandstones remain poorly understood. This study integrated a variety of techniques, such as casting thin section analysis, scanning electron microscopy (SEM), back-scattered electron imagery (BSE), X-ray diffraction (XRD), cathodoluminescence (CL) microscopy, and fluid inclusion, to investigate the lithofacies, diagenetic history, and diagenetic intensity, and also evaluate their controls on reservoir quality. The research results indicated that the Chang 6 sandstones exhibit variable intensity of diagenetic alterations among the various lithofacies, which leads to variable reservoir quality. Mechanical compaction was the most important factor reducing primary porosity. Sandstones of the Ss lithofacies (siltstone to very fine-grained sandstones with graded bedding or ripple laminations) showed the highest loss of primary porosity. Carbonate cements were commonly present in sandstones of the Sc (fine-grained and cross-bedded sandstones) and Sm (fine-grained and massive sandstones) lithofacies near the sandstone–mudstone bounding surface. Sandstones with more authigenic illite rims were able to resist compaction to some extent and were favorable to the preservation of porosity; however, abundant pore-filling illite aggregates commonly bridged pore throats, causing a significant reduction in reservoir quality. Feldspar dissolution porosity leads to a slight enhancement in reservoir quality. Intergranular pores and feldspar dissolution pores are most abundant in the sandstones away from the sandstone–mudstone bounding surface of the Sc lithofacies, resulting in the best reservoir quality, which is followed by sandstones of the Sm lithofacies. Ultimately, four evolution patterns of diagenetic alterations that formed best, moderate, or poor reservoir quality were summarized by linking diagenetic alterations to lithofacies. The research results are conducive to the evaluation of reservoir quality and to understanding the genetic mechanisms of tight sandstones, so they should facilitate hydrocarbon exploration and production in similar lacustrine deep-water gravity-flow reservoirs. • Mechanical compaction is the most important factor reducing primary porosity. • Illite rims can resist compaction and favor the preservation of porosity. • Feldspar dissolution porosity of less than 4% slightly enhanced reservoir quality. • Diagenetic intensity varies with lithofacies, causing variable reservoir quality. [ABSTRACT FROM AUTHOR]

Rare Earth Elements (REEs) are commonly utilized in Earth and environmental sciences to study a variety of geological processes due to their distinct patterns and radioactive-radiogenic decay systems (147Sm-143Nd, 146Sm-142Nd, 138La-138Ce). Advances in analytical techniques now enable the use of REE stable isotopic fractionations to clarify lingering ambiguities in REE systematics. In this study, we employed Nuclear Resonant Inelastic X-ray Scattering (NRIXS) to study the phonon density of states of 151Eu and 161Dy in several pure compounds, as well as in synthetic basalt and andesite glasses, and rhyolite glasses produced under various redox conditions, to determine equilibrium isotopic fractionation factors for the REEs. We additionally utilized Density Functional Theory with a Hubbard U correction (DFT+U) to calculate these factors. Our findings indicate that the directionally averaged mean force constant of Dy3+ is ∼270 N/m across various compounds, while those of Eu2+ and Eu3+ are ∼83 and 214 N/m, respectively, in geologically relevant glasses and other pure compounds. These force constants were then used to estimate those of all REEs using scaling arguments. The results suggest that equilibrium isotopic fractionation should be limited for REEs in igneous rocks, allowing for the interpretation of REE isotopic fractionation in these rocks and minerals as a result of kinetic effects. This could facilitate understanding the role of diffusion in igneous rocks and ore formation. Additionally, our results imply that significant Eu isotopic fractionation could exist in hydrothermal fluids, which could aid in understanding the formation of ore deposits and REE cycling in the oceans. [ABSTRACT FROM AUTHOR]

We report a combined conventional Mössbauer and synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS) study of a series of basalt, andesite, dacite, and rhyolite glasses at temperatures ranging from 5 to 1223 K. These glasses were synthesized under controlled oxygen fugacities and span a wide range of Fe3+/Fe tot ratios. As expected from theory, we find that in these glasses, the inverse of the Lamb-Mössbauer factor (the recoil-free fraction) correlates linearly with the fraction of the conventional Mössbauer spectrum that can be ascribed to Fe3+. Extrapolating the linear relationships to pure Fe3+ and Fe2+ endmembers yields a ratio for the Lamb-Mössbauer factors C of Fe3+ and Fe2+ of 1.203 ± 0.017 (1σ), with no clear dependence on the chemical composition of the glass. We show that the materials studied follow the harmonic approximation up to 1223 K for olivine and 773 K for basaltic glass, allowing us to extrapolate C in temperature. The temperature-dependence of C is well approximated by the formula C = 1.203 ± 0.033 T / 300 over the temperature range 50–750 K. This calibration is used to correct previous redox ratio determinations. We investigate how chemical composition and iron redox state influence the mean force constant of iron in glasses, a key driver of Fe isotopic fractionation during magma generation and differentiation. As previously documented by Dauphas et al. (2014), we find clear correlation between bond strength and iron redox ratio that is secondarily modulated by coordination effects in more alkali-rich felsic magmas. New data on simplified glass compositions reveal that network modifiers, notably K and Na, seem to exert an important control on Fe2+ bond strengths. The refined ratio of Mössbauer factors for Fe2+ and Fe3+ is used to improve on calibrations of iron redox state in geological glasses using XANES spectroscopy. We reevaluate the Fe3+/Fe tot ratio of MORBs based on previously published XANES and Mössbauer data. 0.087 ± 0.005 [ABSTRACT FROM AUTHOR]

Abstract: The global carbon cycle may involve iron carbide as a component of the Earth''s inner core. In this study, we report the first experimental measurements of phonon density of states, sound velocities, and Debye temperatures of Fe3C up to 47GPa and 1450K using the nuclear resonant inelastic X-ray scattering (NRIXS) method in a laser-heated diamond anvil cell. Within the investigated pressure and temperature range, the effect of temperature on compressional velocity v p falls within the measurement uncertainties. The shear velocity vs decreases with increasing temperature in a non-linear fashion: at ~15GPa, vs decreases by ~12% between 300K and 740K; At ~46GPa, temperature produces a ~5% reduction between 300 and 960K and a ~6% further reduction between 960K and 1370–1450K. The high-temperature vs of Fe3C deviates from Birch''s law behavior towards smaller values, potentially matching the anomalously low vs in the inner core under the relevant pressure and temperature conditions. Our results support Fe3C as a major component of the inner core. [Copyright &y& Elsevier]

Interpreting isotopic signatures documented in natural rocks requires knowledge of equilibrium isotopic fractionation factors. Here, we determine equilibrium Fe isotope fractionation factors between several common rock-forming minerals using a comparative approach involving three independent methods: (i) isotopic analyses of natural minerals from a metapelite from Mt. Moosilauke, New Hampshire, for which equilibration temperature and pressure are well constrained to be near the aluminosilicate triple point (T ≃ 500 °C, P ≃ 4 kbar), (ii) Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements of Fe force constants of minerals, and (iii) Density Functional Theory (DFT) ab initio calculations of Fe force constants of minerals. The minerals studied for Fe isotopes include, in increasing order of their β-factors: garnet < ilmenite ≈ fayalite < biotite < tourmaline < muscovite ≈ plagioclase. Some of this ordering is affected by the presence of Fe3+ in the minerals, which tends to form stiffer bonds and be associated with heavy Fe isotope enrichments relative to Fe2+. We are, however, able to assess the magnitude of the effect of the ratio Fe3+/ΣFe on equilibrium fractionation factors, notably on the ilmenite-hematite solid solution. Equilibrium Fe isotopic fractionation factors between garnet, ilmenite, biotite, tourmaline and fayalite are determined. We also report Mg and Ti isotopic compositions of selected Moosilauke minerals that allow us to better constrain the equilibrium fractionation factors for garnet-biotite-tourmaline (Mg isotopes) and biotite-ilmenite (Ti isotopes). We show how the newly determined equilibrium fractionation factors can be used to address diverse problems in Earth and planetary sciences, notably (i) Fe and Mg isotopic fractionation during anatexis, (ii) Fe isotopic fractionation in lunar ilmenite, and (iii) Ti isotopic fractionation during fluvial transport of minerals. [ABSTRACT FROM AUTHOR]

The isotopic compositions of iron in major mantle minerals may record chemical exchange between deep-Earth reservoirs as a result of early differentiation and ongoing plate tectonics processes. Bridgmanite (Bdg), the most abundant mineral in the Earth's lower mantle, can incorporate not only Al but also Fe with different oxidation states and spin states, which in turn can influence the distribution of Fe isotopes between Bdg and ferropericlase (Fp) and between the lower mantle and the core. In this study, we combined first-principles calculations with high-pressure nuclear resonant inelastic X-ray scattering measurements to evaluate the effects of Fe site occupancy, valence, and spin states at lower-mantle conditions on the reduced Fe partition function ratio (β -factor) of Bdg. Our results show that the spin transition of octahedral-site (B-site) Fe3+ in Bdg under mid-lower-mantle conditions generates a +0.09‰ increase in its β -factor, which is the most significant effect compared to Fe site occupancy and valence. Fe2+-bearing Bdg varieties have smaller β -factors relative to Fe3+-bearing varieties, especially those containing B-site Fe3+. Our models suggest that Fe isotopic fractionation between Bdg and Fp is only significant in the lowermost mantle due to the occurrence of low-spin Fe2+ in Fp. Assuming early segregation of an iron core from a deep magma ocean, we find that neither core formation nor magma ocean crystallization would have resulted in resolvable Fe isotope fractionation. In contrast, Fe isotopic fractionation between low-spin Fe3+-bearing Bdg/Fe2+-bearing Fp and metallic iron at the core-mantle boundary may have enriched the lowermost mantle in heavy Fe isotopes by up to +0.20‰. [ABSTRACT FROM AUTHOR]

In order to detect weak signal photons from background radiation, using an array of InGaAs/InP single-photon avalanche diode (SPAD) as a detector is receiving increasing interest. Firstly, the canonical structure and operation principle of SPAD are analyzed. Then, based on the basic parameters (excess bias, operating temperature, absorption region thickness, and multiplication region thickness), the integrated SPAD model of performance parameters, which combines photon detection efficiency (PDE) and dark count rate (DCR), is built. Moreover, a scheme of utilizing SPADs array to detect weak signal photons and an accurate bit error rate (BER) model of photon-counting communication with the limitation of non-ideal factors of SPAD are studied. Then, the joint model of the integrated SPAD model and the BER model is founded. According to the joint model, the design considerations of SPAD to improve the BER in photon-counting communication are investigated. In addition, in regard to a specific photon-counting communication system, the basic parameters of SPAD can be effectively optimized through the joint model. [ABSTRACT FROM AUTHOR]

Abstract Iron is the most abundant transition metal in the Earth's interior, yet considerable uncertainties remain as to why mantle-derived rocks have diverse iron isotopic compositions. In particular, the isotopic fractionation behavior of iron in the lower-mantle minerals bridgmanite and ferropericlase are largely unexplored. The reason is that it is challenging to study isotopic fractionation at the high pressures relevant to the deep mantle. Here we report in situ measurements of the mean force constants of iron bonds in these minerals pressurized in diamond anvil cells using the technique of nuclear resonant inelastic X-ray scattering (NRIXS). We find that the transition from high- to low-spin iron in ferropericlase ((Mg 0.75 Fe 0.25)O) at approximately 60 GPa drastically stiffens its iron bonds in the low-spin state. The mean force constant of iron bonds in both Fe-bearing and (Fe,Al)-bearing bridgmanite exhibits softening by 21% at approximately 40–60 GPa, which seems to be associated with changes in the iron local environment during the transition from low to high quadrupole splitting states. These results indicate that in the lower mantle, low-spin ferropericlase is enriched in heavy iron isotopes relative to bridgmanite and metallic iron by +0.15‰ and +0.12‰, respectively. Based on these results, we investigate whether terrestrial magma ocean crystallization could have fractionated iron isotopes. We conclude that this process cannot be responsible for the heavy iron isotope enrichment measured in terrestrial basalts. Highlights • Iron isotope fractionation factors in lower mantle minerals were determined. • Spin states and local site influence the high pressure iron isotopic fractionation. • Limited iron isotope fractionation between minerals and melts is found. • The magma ocean crystallization did not cause terrestrial iron isotopic variations. [ABSTRACT FROM AUTHOR]

Sound velocities of cementite Fe 3 C have been measured up to 1.5 Mbar and at 300 K in a diamond anvil cell using the nuclear resonant inelastic X-ray scattering (NRIXS) technique. From the partial phonon density of states (pDOS) and equation of state (EOS) of Fe 3 C, we derived its elastic parameters including shear modulus, compressional ( V P ) and shear-wave ( V S ) velocities to core pressures. A pressure-induced spin-pairing transition in the powdered Fe 3 C sample was found to occur gradually between 10 and 50 GPa by the X-ray Emission Spectroscopy (XES) measurements. Following the completion of the spin-pairing transition, the V P and V S of low-spin Fe 3 C increased with pressure at a markedly lower rate than its high-spin counterpart. Our results suggest that the incorporation of carbon in solid iron to form iron carbide phases, Fe 3 C and Fe 7 C 3 , could effectively lower the V S but respectively raise the Poisson's ratio by 0.05 and 0.07 to approach the seismically observed values for the Earth's inner core. The comparison with the preliminary reference Earth model (PREM) implies that an inner core composition containing iron and its carbon-rich alloys can satisfactorily explain the observed seismic properties of the inner core. [ABSTRACT FROM AUTHOR]

• A scheme of letting recording pulses pass through low-pass finite impulse response (FIR) filter to realize SPAD receivers without photon counting is proposed. • The Monte-Carlo model of SPAD-based optical wireless communications (OWC) system is built and verified with experimental results. • A simple and accurate signal estimation and decision algorithm is developed to demodulate the low-pass signal based on the signal-dependent noise model. • The proposed scheme has great potential to realize a simplified and effective SPAD-based OWC system without photon counting. Single photon avalanche diode (SPAD) attracts increasing interests to realize photon-sensitive receivers for optical wireless communications (OWC). In SPAD receivers, the bit information is extracted by photon counting process, which will increase the burden of data processing and storage. To remove complex photon counting process, we propose a scheme of letting recording pulses pass through low-pass finite impulse response (FIR) filter to realize a SPAD receiver without photon counting. Based on the SPAD operation principles, the Monte-Carlo model of SPAD-based OWC system is built and verified with experimental results. Moreover, based on the signal-dependent noise model, a simple and accurate signal estimation and decision algorithm is developed to demodulate the low-pass signal. On this basis, the system error performance under different operation conditions is investigated. The results indicate that utilizing the proposed algorithm, the system error performance is improved 1- to 3-orders of magnitude better than conventional algorithm, which depends on additive Gaussian noise model. [ABSTRACT FROM AUTHOR]

The attenuation characteristics of ultraviolet (UV) and infrared transmitting in the atmosphere is analyzed, when long-haul Non-Line-of-Sight (NLOS) optical scattering communication is considered. The effects of Rayleigh and Mie scattering to link performance are presented. Under given geometric configurations, a critical range R C is found. When communication range is shorter than R C , the attenuation of UV is lower than that of infrared. But the path loss of UV increases rapidly, while the path loss of infrared increases much slower. When communication range is longer than R C , the attenuation of UV is higher than that of infrared. Numerical values of R C under different geometries are analyzed. It is also indicated that, under arbitrary geometric configurations, the impact of the Rayleigh scattering to infrared scattering communication is weak, but to UV scattering, the Rayleigh scattering effect cannot be ignored. [ABSTRACT FROM AUTHOR]

Protein kinase C associated kinase (PKK) regulates NF-κB activation and is required for the survival of certain lymphoma cells. Mice lacking PKK die soon after birth, and previous studies suggest that the role of PKK in B cell development might be context dependent. We have generated a mouse strain harboring conditional null alleles for PKK and a Cre -recombinase transgene under the control of the endogenous CD19 promoter. In the present study, we show that knockout of PKK in B cells results in the reduction of long-lived recirculating mature B cell population in lymph nodes and bone marrow as well as a decrease in peritoneal B1 cells, while PKK deficiency has no apparent effect on early B cell development in bone marrow or the development of follicular and marginal zone B cells in the spleen. In addition, we demonstrate that PKK-deficient B cells display defective proliferation and survival responses to stimulation of B cell receptor (BCR), which may underlie the reduction of recirculating mature B cells in PKK mutant mice. Consistently, BCR-mediated NF-κB activation, known to be required for the survival of activated but not resting B cells, is attenuated in PKK-deficient B cells. Thus, our results reveal a critical role of PKK in the maintenance of recirculating mature B cells as well as the development of B1 cells in mice. [ABSTRACT FROM AUTHOR]

Eight spinel-group minerals were synthesized by a flux-growth method producing spinels with varying composition and Fe 3+ /Fe tot ratios. The mean force constants of iron bonds in these minerals were determined by synchrotron nuclear resonant inelastic X-ray scattering (NRIXS) in order to determine the reduced isotopic partition function ratios ( β -factors) of these spinels. The mean force constants are strongly dependent on the Fe 3+ /Fe tot of the spinel but are independent, or weakly dependent on other structural and compositional parameters. From our spectroscopic data, it is found that a single redox-dependent calibration line accounts for the effects of Fe 3+ /Fe tot on the β -factors of spinels. This calibration successfully describes the equilibrium Fe isotopes fractionation factors between spinels and silicates (olivine and pyroxenes). Our predictions are in excellent agreement with independent determinations for the equilibrium Fe isotopic fractionations for the magnetite–fayalite and the magnetite–hedenbergite couples. Our calibration applies to the entire range of Fe 3+ /Fe tot ratios found in natural spinels and provides a basis for interpreting iron isotopic variations documented in mantle peridotites. Except for a few exceptions, most of the samples measured so far are in isotopic disequilibrium, reflecting metasomatism and partial melting processes. [ABSTRACT FROM AUTHOR]

Non-melanoma skin cancer represents the most common cancer in the United States. Squamous cell carcinoma (SCC) of the skin is a subtype of NMSC that shows a greater potential for invasion and metastasis. The current study identifies the protein kinase C-associated kinase (PKK), which is also known as the receptor-interacting protein kinase 4, as a suppressor of tumor growth in SCC of the skin. We show that expression of PKK is decreased in human SCC of the skin compared with normal skin. Further, suppression of PKK in human keratinocytes leads to increased cell proliferation. The use of RNA interference to reduce PKK expression in keratinocytes leads to an increase in S phase and in proteins that promote cell cycle progression. Consistent with the results obtained from cell culture, there is a marked increased tumorigenesis after PKK knockdown in a xenotransplant model and in soft agar assays. The loss of tumor suppression involves the NF-κB and p63 pathways. NF-κB is inhibited through inhibition of inhibitor of NF-κB kinase function and there is increased nuclear TP63 activity after PKK knockdown. This study opens new avenues both in the discovery of disease pathogenesis and for potential treatments. [ABSTRACT FROM AUTHOR]

• We measure the melting and solid phase relations of Fe 0.8 Ni 0.1 Si 0.1 up to 83 GPa. • Independent melt detection techniques show excellent agreement and reproducibility. • Synchrotron Mössbauer spectroscopy detects the very first onset of melting. • X-ray diffraction constrains in-situ sample pressure evolution during heating. • 10 mol% Si decreases the melting temperature of Fe 0.9 Ni 0.1 by up to 500 K at 150 GPa. Many studies have suggested silicon as a candidate light element for the cores of Earth and Mercury. However, the effect of silicon on the melting temperatures of core materials and thermal profiles of cores is poorly understood, due to disagreements among melt detection techniques, uncertainties in sample pressure evolution during heating, and sparsity of studies investigating the combined effects of nickel and silicon on the phase diagram of iron. In this study we develop a multi-technique approach for measuring the high-pressure melting and solid phase relations of iron alloys and apply it to Fe 0.8 Ni 0.1 Si 0.1 (Fe-11wt%Ni-5.3wt%Si), a composition compatible with recent estimates for the cores of Earth and Mercury. This approach combines results (20-83 GPa) from two atomic-level techniques: synchrotron Mössbauer spectroscopy (SMS) and synchrotron x-ray diffraction (XRD). Melting is independently detected by the loss of the Mössbauer signal, produced exclusively by solid-bound iron nuclei, and the onset of a liquid diffuse x-ray scattering signal. The use of a burst heating and background updating method for quantifying changes in the reference background during heating facilitates the determination of liquid diffuse signal onsets and leads to strong reproducibility and excellent agreement in melting temperatures determined separately by the two techniques. XRD measurements additionally constrain the hcp-fcc phase boundary and in-situ pressure evolution of the samples during heating. We apply our updated thermal pressure model to published SMS melting data on fcc -Fe and fcc -Fe 0.9 Ni 0.1 to precisely evaluate the effect of silicon on melting temperatures. We find that the addition of 10 mol% Si to Fe 0.9 Ni 0.1 reduces melting temperatures by ∼250 K at low pressures (<60 GPa) and flattens the hcp-fcc phase boundary. Extrapolating our results, we constrain the location of the hcp-fcc-liquid quasi-triple point at 147±14 GPa and 3140±90 K, which implies a melting temperature reduction of 500 K compared with Fe 0.9 Ni 0.1. The results demonstrate the advantages of combining complementary experimental techniques in investigations of melting under extreme conditions. [ABSTRACT FROM AUTHOR]

Abstract: We have measured the effects of the coupled substitution of Fe3+ and Al on the density and compressibility of mantle silicate perovskite (Pv) up to 95GPa. X-ray emission spectroscopy and synchrotron Mössbauer spectroscopy reveal a rapid increase in the population of low-spin Fe3+ in Fe3+, Al-bearing Pv over a narrow pressure range near 70GPa, which is in sharp contrast with Al-free Fe3+-bearing Pv, where Fe3+ undergoes a gradual spin transition, and with Al-free Fe2+-bearing Pv, where Fe2+ does not become low spin. At low pressure, Fe3+ and Al expand the perovskite lattice. However, near the pressure range of the abrupt increase in the low-spin population, the unit-cell volume of Fe3+, Al-bearing Pv becomes similar to that of Mg-endmember Pv, while those of Al-free Fe3+-bearing Pv and Al-free Fe2+-bearing Pv remain larger throughout the lower mantle. Consequently, Pv in Al-rich systems should have lower density in the shallow lower mantle but similar or greater density than Pv in pyrolite in the deep lower mantle, affecting the buoyancy and mechanical stability of heterogeneities. Although the Fe3+ spin transition in Pv is unlikely to cause a seismic discontinuity at mantle temperatures, it may result in a large change in bulk sound speed at 1200–1800km depth, such that a vertically extending structure with an elevated amount of Fe3+ would generate slower and faster anomalies above and below the depth of the spin transition, respectively, relative to the surrounding mantle. This may have important implications for bulk sound speed anomalies observed at similar depths in seismic tomography studies. [Copyright &y& Elsevier]

Abstract: Recent studies have indicated that a significant amount of iron in MgSiO3 perovskite (Pv) is Fe3+ (Fe3+/ΣFe=10–60%) due to crystal chemistry effects at high pressure (P) and that Fe3+ is more likely than Fe2+ to undergo a high-spin (HS) to low-spin (LS) transition in Pv in the mantle. We have measured synchrotron Mössbauer spectroscopy (SMS), X-ray emission spectroscopy (XES), and X-ray diffraction (XRD) of Pv with all iron in Fe3+ in the laser-heated diamond-anvil cell to over 100GPa. Fe3+ increases the anisotropy of the Pv unit cell, whereas Fe2+ decreases it. In Pv synthesized above 50GPa, Fe3+ enters into both the dodecahedral (A) and octahedral (B) sites approximately equally, suggesting charge coupled substitution. Combining SMS and XES, we found that the LS population in the B site gradually increases with pressure up to 50–60GPa where all Fe3+ in the B site becomes LS, while Fe3+ in the A site remains HS to at least 136GPa. Fe3+ makes Pv more compressible than Mg-endmember below 50GPa because of the gradual spin transition in the B site together with lattice compression. The completion of the spin transition at 50–60GPa increases bulk modulus with no associated change in density. This elasticity change can be a useful seismic probe for investigating compositional heterogeneities associated with Fe3+. [Copyright &y& Elsevier]

Abstract: Magnetic, elastic, thermodynamic, and vibrational properties of the most iron-rich sulfide, Fe3S, known to date have been studied with synchrotron Mössbauer spectroscopy (SMS) and nuclear resonant inelastic X-ray scattering (NRIXS) up to 57 GPa at room temperature. The magnetic hyperfine fields derived from the time spectra of the synchrotron Mössbauer spectroscopy show that the low-pressure magnetic phase displays two magnetic hyperfine field sites and that a magnetic collapse occurs at 21 GPa. The magnetic to non-magnetic transition significantly affects the elastic, thermodynamic, and vibrational properties of Fe3S. The magnetic collapse of Fe3S may also affect the phase relations in the iron–sulfur system, changing the solubility of sulfur in iron under higher pressures. Determination of the physical properties of the non-magnetic Fe3S phase is important for the interpretation of the amount and properties of sulfur present in the planetary cores. Sound velocities of Fe3S obtained from the measured partial phonon density of states (PDOS) for 57Fe incorporated in the alloy show that Fe3S has higher compressional and shear wave velocity than those of hcp-Fe and hcp-Fe0.92Ni0.08 alloy under high pressures, making sulfur a potential light element in the Earth''s core based on geophysical arguments. The VP and VS of the non-magnetic Fe3S follow a Birch''s law trend whereas the slopes decrease in the magnetic phase, indicating that the decrease of the magnetic moment significantly affects the sound velocities. If the Martian core is in the solid state containing 14.2 wt.% sulfur, it is likely that the non-magnetic Fe3S phase is a dominant component and that our measured sound velocities of Fe3S can be used to construct the corresponding velocity profile of the Martian core. It is also conceivable that Fe3P and Fe3C undergo similar magnetic phase transitions under high pressures. [Copyright &y& Elsevier]

• Elastic and magnetic properties of inner core candidate Fe 3 P up to 1.5 Mbar. • Magnetic transition at 21.5 GPa has significant effect on elastic properties. • Fe 3 P bears low V s and high Poisson's ratio at inner core pressures. • Fe 3 (S, P) helps explain the seismic observations of the inner core. Phosphorus (P) is considered a possible light element alloying with iron (Fe) in the Earth's core due to its siderophile nature and the ubiquity of P-bearing iron alloys in iron meteorites. The sequestration of P by liquid metals during the core formation possibly results in the relatively low concentration of P in the bulk silicate Earth. In this study, we performed single-crystal and powder X-ray diffraction, synchrotron Mössbauer spectroscopy and nuclear resonant inelastic X-ray scattering measurements in diamond anvil cells to investigate the elastic and magnetic properties of Fe 3 P under high pressures. Our X-ray diffraction results suggest that there is no structural phase transition up to 111 GPa. However, a volume collapse was observed at 21.5 GPa in Fe 3 P, ascribed to a magnetic transition as evidenced by synchrotron Mössbauer spectroscopy results. Fitting the volume-pressure data by the Birch-Murnaghan equation of state gives bulk modulus K T 0 = 162.4 (7) GPa, its first pressure derivative K T 0 ′ = 4.0 (fixed) and zero-pressure volume V 0 = 370.38 (6) Å3 for the magnetic phase and K T 0 = 220 (7) GPa, K T 0 ′ = 4.0 (fixed) and V 0 = 357 (1) Å3 for the non-magnetic phase. Sound velocities of Fe 3 P were determined up to 152 GPa by nuclear resonant inelastic X-ray scattering, demonstrating that Fe 3 P bears a low shear velocity and high Poisson's ratio at core pressures compared to Fe and Fe 3 S. When forming a solid solution Fe 3 (S,P) with Fe 3 S at core pressures, Fe 3 P may favorably influence the elastic properties of Fe 3 (S,P) to match the seismic observations of the inner core. [ABSTRACT FROM AUTHOR]

The Earth's iron-dominant core is known to contain nickel from cosmochemical analysis and some amount of light elements from geophysical constraints on density and seismic wave velocities. Although there have been several studies to constrain thermoelastic properties of iron-alloys, there has been no systematic study on the effects of nickel and light elements on properties of iron using the same experimental methods and data analysis approach. We conducted nuclear resonant inelastic X-ray scattering and X-ray diffraction experiments on body-centered cubic and hexagonal close-packed (hcp) Fe 0.91 Ni 0.09 and Fe 0.8 Ni 0.1 Si 0.1 up to 104 GPa and 86 GPa, respectively, and compare to similar measurements conducted on hcp-Fe up to 171 GPa. Specifically, we determine the Debye sound velocity from the low-energy transfer region of the (partial) phonon density of states (DOS) using the equation of state determined for each material and a new approach which utilizes information criteria and probability distributions. Nickel decreases the shear velocity of iron, while 10 at% Si has little to no effect on the shear velocity of Fe 0.91 Ni 0.09. We observe that the shape of the phonon DOS of these alloys remains similar with increasing pressure. In the measured compression range, we therefore apply a generalized scaling law to describe the volume dependence of the phonon DOS and find that the vibrational Grüneisen parameters of hcp-Fe 0.91 Ni 0.09 are nearly indistinguishable from those hcp-Fe and those for Fe 0.8 Ni 0.1 Si 0.1 trend lower. From the vibrational free energy, we constrain the harmonic vibrational component of thermal pressure, which shows a significant positive deviation from theoretical calculations of hcp-Fe at pressures and temperatures of Earth's core. Collectively, our results demonstrate that the effects of nickel should be considered when modeling iron-rich planetary cores. • Nuclear resonant inelastic X-ray scattering on Fe-Ni and Fe-Ni-Si to 104 and 86 GPa • New Debye velocity determination method yields improved results and uncertainties. • Nickel decreases the shear velocity of iron, and 10 at% Si has little to no effect. • Vibrational Grüneisen parameters of hcp Fe-Ni-Si trend lower than Fe and Fe-Ni • hcp-Fe harmonic vibrational thermal pressure deviates from theoretical calculations. [ABSTRACT FROM AUTHOR]