Perovskite, CaTiO3, originally described as a cubic mineral, is known to have a distorted (orthorhombic) crystal structure. We herein report on the discovery of natural cubic perovskite. This was ...identified in gehlenite-bearing rocks occurring in a pyrometamorphic complex of the Hatrurim Formation (the Mottled Zone), in the vicinity of the Dead Sea, Negev Desert, Israel. The mineral is associated with native α-(Fe,Ni) metal, schreibersite (Fe3P), and Si-rich fluorapatite. The crystals of this perovskite reach 50 µm in size and contain many micrometer-sized inclusions of melilitic glass. The mineral contains significant amounts of Si substituting for Ti (up to 9.6 wt% SiO2), corresponding to 21 mol% of the davemaoite component (cubic perovskite-type CaSiO3), in addition to up to 6.6 wt% Cr2O3. Incorporation of trivalent elements results in the occurrence of oxygen vacancies in the crystal structure; this is the first example of natural oxygen-vacant ABO3 perovskite with the chemical formula Ca(Ti,Si,Cr)O3-δ (δ ∼0.1). Stabilization of cubic symmetry (space group Pm3m) is achieved via the mechanism not reported so far for CaTiO3, namely displacement of an O atom from its ideal structural position (site splitting). The mineral is stable at atmospheric pressure to 1250 ± 50 °C; above this temperature, its crystals fuse with the embedded melilitic glass, yielding a mixture of titanite and anorthite upon melt solidification. The mineral is stable upon compression to at least 50 GPa. The a lattice parameter exhibits continuous contraction from 3.808(1) Å at atmospheric pressure to 3.551(6) Å at 50 GPa. The second-order truncation of the Birch-Murnaghan equation of state gives the initial volume V0 equal to 55.5(2) Å3 and room temperature isothermal bulk modulus K0 of 153(11) GPa. The discovery of oxygen-deficient single perovskite suggests previously unaccounted ways for incorporation of almost any element into the perovskite framework up to pressures corresponding to those of the Earth's mantle.
In clinics that allow extended culture up to Day7, on average 5% of embryos have a 48-hour delay in development. It has been showed that embryos from patients over 35 years of age take longer to form ...a blastocyst. The main aim - to evaluate the effect of extended embryo culture up to Day7 on embryo quality, ploidy and reproductive cycle outcomes.
This was a retrospective cohort study in a private Delta Fertility Clinic of consecutive female infertility patients (n = 422) between Sept 2021-Sept 2022. Average age of the patients was 39,7 years who underwent frozen embryo transfer (FET) of a single euploid day 5, 6 or 7 blastocyst. Then we compared the outcomes in the 5Day, 6Day and 7Day groups.The results of culture and subsequent biopsy of trophoectoderm with PGT-A of 2095 blastocysts (1516 were tested with PGT-A) in 482 cycles were analyzed, of these, embryos Day7 suitable for biopsy were 9.8% (149). Blastocysts were classified as good (AA/AB/BA/BB) or poor (AC/BC/CA/CB). Cultivation performed in single drops, biopsy was performed using the flicking method. Statistical analysis was performed using the Pearson's Chi-Squared Test.
In 3.4% of cases, patients had only Day7 blastocysts. Poor quality blastocysts were predominant in D7 blastocyst group (good quality: 91.0%, 65.2%, 46.3%; poor quality: 9.0%, 34.8%, 53.7%, P < 0.001 for D5, D6 and D7 blastocysts; respectively). The number of euploid embryos was significantly lower in the Day6 and Day7 group compared to Day5 (51.8% and 50.0% vs 64.4%, p<0.001 and p<0.001). We found no differences in cycle outcomes, implantation rate was 52,7%, 49,6% and 38,5% for D5, D6 and D7 respectively (P=0,474). We speculate that this may be due to the small number of Day7 embryo transfers (n=13), but we have 5 live births in our clinic after euploid Day7 embryo transfer.
Embryo quality and ploidy are statistically significantly lower in the Day7 group, no difference in implantation rate and in cycle outcomes was found. Cultivation before Day7 (only with PGT-A) should be introduced into routine practice as an option for patients over 35 years of age or with a known poor prognosis.
Stillwellite, ideally CeBSiO5, is a rare mineral, however, its discovery stimulated the intense studies of a new class of stillwellite-like materials with remarkable electrical and optical ...properties. With the use of the modern non–ambient single crystal X-ray diffraction, this work sheds some light on the evolution of stillwellite crystal structure during the process of high-temperature transformations noted for the most of these practically important compounds. Here a sample of natural stillwellite stillwellite-(Ce) from the Darai-Pioz alkaline massif (Tadjikistan) has been studied by means of electron microscopy, IR spectroscopy, single crystal and powder X-ray diffraction (XRD) in a wide temperature range from −180 up to 1200 °C. The dielectric properties are also measured in the range from −180 up to 500 °C. The low (LT) and the high temperature (HT) structure deformation and transformation are described from single XRD data including the detail analysis of deformation of cationic polyhedra on heating. The disorder-to-order phase transition occurs in the stillwellite structure at about 450–500 °C. Both LT (disordered) and HT (ordered) modifications are characterized as relatively low expansion materials: αvolume = 15 and 19 × 10-6 °C-1 for LT and HT phases, respectively. The high-temperature transformation of stillwellite involves some negative thermal expansion (αvolume = −11 × 10-6 °C-1) caused by order-disorder process and presumably by the partial oxidation of Ce3+ to Ce4+. The dielectric properties show a maximum in the region of transformation as well, but the study of dielectric hysteresis loops did not confirm the ferroelectric order of stillwellite structure at room temperature. The high-temperature behavior and the decomposition process of stillwellite are dictated by the partial oxidation of cerium.
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•Crystal structure of stillwellite, CeBSiO5, is studied by single crystal XRD in the temperature range from −180 up to 930 °C.•Order-disorder phase transition occurs in the range of 450–500 °C.•CeBSiO5 behaves like a linear dielectric material with a maximum of dielectric characteristics in the region of order disorder transformation.•The LT (disordered) and HT (ordered) phases are characterized as the low thermal expansion materials.•The negative thermal expansion is caused by order-disorder process and presumably by the partial oxidation of Ce3+ to Ce4+.
The effects of dopamine (DA) on a persistent Na(+) current (I(NaP)) in layer V-VI prefrontal cortical (PFC) pyramidal cells were studied using whole cell voltage-clamp recordings in rat PFC slices. ...After blocking K(+) and Ca (2+) currents, a tetrodotoxin-sensitive I(NaP) was activated by slow depolarizing voltage ramps or voltage steps. DA modulated the I(NaP) in a voltage-dependent manner: increased amplitude of I(NaP) at potentials more negative than -40 mV, but decreased at more positive potentials. DA also slowed the inactivation process of I(NaP). The D1/D5 dopamine receptor agonists SKF 38393, SKF 81297, and dihydrexidine (3-10 microM), but not the dopamine D2/D3 receptor agonist qiunpirole (1-20 microM), mimicked the effects of DA on I(NaP). Modulation of I(NaP) by D1/D5 agonists was blocked by the D1/D5 antagonist SCH23390. Bath application of specific protein kinase C inhibitor, chelerhythrine, or inclusion of the specific protein kinase C inhibiting peptide(19-36) in the recording pipette, but not protein kinase A inhibiting peptide(5-24), blocked the effect of D1/D5 agonists on I(NaP). In current-clamp recordings, D1/D5 receptors activation enhanced the excitability of cortical pyramidal cells. Application of the D1/D5 agonist SKF 81297 induced a long-lasting decrease in the first spike latency in response to depolarizing current ramp. This was associated with a shift in the start of nonlinearity in the slope resistance to more negative membrane potentials. We proposed that this effect is due to a D1/D5 agonist-induced leftward shift in the activation of I(NaP). This enables DA to facilitate the firing of PFC neurons in response to depolarizing inputs.
Comparative study was made of the rhizospheree microbiomes of two cultivars of sorghum (
Sorghum bicolor
cvs. Sucro 506 and Biomass 133) grown on soils with anthropogenic polyelement anomalies and on ...a background (control) soil. The study used traditional culture-based and culture-independent metagenomic approaches. In soils contaminated with heavy metals, we found decreased numbers of culturable bacteria and quantitative changes in the populations of actinomycetes and micromycetes. The relative abundance of the families whose members were able to resist heavy metals was found to increase in the rhizospheric communities. The taxonomic profile of the microbial communities at the phylum level did not differ significantly between cultivars. The Shannon diversity and the abundance of actinomycete families in the rhizosphere of cv. Biomass 133were greater than those for cv. Sucro 506. Significant differences were found between cultivars for the number of rhizospheric microorganisms resistant to heavy metals.
Green microalgae
Lobosphaera
sp. IPPAS С-2047 and
Micractinium simplicissimum
IPPAS С-2056 were examined for the first time for cell tolerance to elevated concentrations of manganese applied in the ...form of MnCl
2
. Analyses of cell photosynthetic activity by chlorophyll fluorometry and the dynamic patterns of absorbance changes of cell suspensions at the peak of chlorophyll absorption revealed differential tolerance of two microalgae species to manganese. The acute toxicity assayed in 4-day treatments became apparent at manganese concentrations equal to or higher than 1 g/L for
M. simplicissimum
cells and at concentrations above 10 g/L for
Lobosphaera
sp. Transmission electron microscopy and energy-dispersive X-ray spectroscopy were used to study the subcellular distribution of manganese in microalgal cells under elevated nontoxic concentrations of manganese in the medium. The results with
Lobosphaera
sp. established the lack of individual manganese-containing inclusions on cell surfaces and in the cell interior; the intracellular distribution of manganese was dispersed with elevated accumulation of this element in the region of thylakoids and plastoglobules. The occurrence of manganese and phosphorus in plastoglobules was found for the first time. Apparently, these compartments become accessible for accumulation of Mn and P upon the translocation of thylakoid components during stress-induced disassembling of their structure. The cells of
M. simplicissimum
were able to oxidize the exoplasmic Mn
2+
with the formation of manganese nanoparticles in the intercellular matrix as well as on the cell surface and within the cell walls. In addition, the manganese permeating into the cells was shown to compartmentalize in vacuoles and bind to the polyphosphate granules.
Photogeneration of hydrogen in microalgae is thought to be among the mechanisms increasing their resilience to stresses including those caused by nutrient deprivation by re-routing the flow of ...electrons and reducing power in the cell. Metabolism of phosphorus (P), an essential nutrient, and its reserve forms such as polyphosphate (PolyP), is affected by and plays a role in the responses to diverse stresses, too. However, the potential interplay of the capability of photogeneration of hydrogen and turnover of phosphorus-rich inclusions in stressed microalgae cells so far escaped the attention of researchers. Here, we present a quantitative ultrastructural view of the turnover of P-rich inclusions in the model microalga
Chlamydomonas reinhardtii
strains, the parent strain CC-425 and its
hydEF-1
mutant lacking hydrogenase activity as a function of sulfur and oxygen availability in the medium. In addition to the electron microscopy cell image analysis of the studied strains, we followed the elemental composition of the inclusions in different (sub) compartments of the cells obtained with energy dispersive X-ray spectroscopy. The stress caused by sulfur deprivation and subsequent transition of the microalgae culture to anaerobic conditions declined the size of phosphorus-containing inclusions but increased their number in the parent strain. Overall, the accumulation of the phosphorus-rich inclusions in
hydEF-1
mutant was much lower than in the fully functional parent strain regardless of the cultivation conditions. We believe that impaired hydrogenase activity and correspondingly reduced sink of electrons and reducing power in the mutant strain indirectly affects the turnover of P and its reserves in the cell. These effects were manifested by the changes in the abundance, morphology, and elemental composition of the P-containing inclusions. We hypothesized that the sulfur-deprivation stress increased the initiation of the biosynthesis of PolyP chains, but their elongation and hence the formation of large PolyP-containing inclusions was hindered by anaerobiosis.
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