Relatively oxidized conditions for diamond formation at Udachnaya (Siberia)

Thanks to the physical strength of diamonds and their relatively unreactive chemical nature, their mineral inclusions may remain exceptionally preserved from alteration processes and chemical exchanges with surrounding minerals, fluids and/or melts following diamond formation. Cr-bearing spinels are relatively common inclusions found in peridotitic diamonds and important oxybarometers providing information about the oxygen fugacity (fO2) of their source mantle rocks. Here, we investigated a magnesiochromite-olivine touching pair in a diamond from the Udachnaya kimberlite (Siberia) by in situ single-crystal X-ray diffraction and energy-domain synchrotron Mossbauer spectroscopy, aiming to constrain the physical-chemical conditions of diamond formation and to explore the redox state of this portion of the Siberian craton when the diamond was formed. The P-T-fO(2) entrapment conditions of the inclusion pair, determined by thermo- and oxybarometric analyses, are similar to 5.7(0.4) GPa and similar to 1015(50) ? (although entrapment at higher T and re-equilibration during subsequent mantle storage are also possible) and fO(2) near the enstatite-magnesite-olivine-diamond (EMOD) buffer. The determined fO(2) is similar to, or slightly more oxidized than, those of xenoliths from Udachnaya, but whilst the xenoliths last equilibrated with the surrounding mantle just prior to their entrainment in the kimberlite at similar to 360 Ma, the last equilibration of the inclusion pair is much older, occurring at 3.5-3.1, similar to 2 or similar to 1.8 Ga before final encapsulation in its host diamond. Hence, the similarity between xenoliths and inclusion fO(2) values indicates that the modern redox state of this portion of the Siberian lithosphere was likely attained relatively early after its formation and may have persisted for billions of years after diamond formation, at least at the local scale. Moreover, the oxygen fugacity determination for the inclusion pair provides direct evidence of diamond formation near the EMOD buffer and is consistent with recent models suggesting relatively oxidized, water-rich CHO fluids as the most likely parents for lithospheric diamonds

Molecular characterization of intergeneric hybrids between Malus and Pyrus

Apple (Malus) and pear (Pyrus) are economically important fruit crops well known for their unique textures, flavours, and nutritional qualities. Both genera are characterised by a distinct pattern of secondary metabolites, which directly affect not only resistance to certain diseases, but also have significant impacts on the flavour and nutritional value of the fruit. The identical chromosome numbers, similar genome size, and their recent divergence date, together with DNA markers have shown that apple and pear genomes are highly co-linear. This study utilized comparative genomic approaches, including simple sequence repeats, high resolution single nucleotide polymorphism melting analysis, and single nucleotide polymorphism chip analysis to identify genetic differences among hybrids of Malus and Pyrus, and F2 offspring. This research has demonstrated and validated that these three marker types, along with metabolomics analysis are very powerful tools to detect and confirm hybridity of progeny derived from crosses between apple and pear in both cross directions. Furthermore, this work analysed the genus-specific metabolite patterns and the resistance to fire blight (Erwinia amylovora) in progeny. The findings of this work will enhance and accelerate the breeding of novel tree fruit crops that benefit producers and consumers, by enabling marker assisted selection of desired traits introgressed between pear and apple

The impact of COVID-19 on radiological findings in patients accessing the emergency department: a multicentric study

The aim of this multicentric study is to illustrate how the COVID-19 pandemic lockdown affected the workload and outcomes of radiological examinations in emergency radiology

Diamond-inclusion system recording old deep lithosphere conditions at Udachnaya (Siberia)

Diamonds and their inclusions are unique fragments of deep Earth, which provide rare samples from inaccessible portions of our planet. Inclusion-free diamonds cannot provide information on depth of formation, which could be crucial to understand how the carbon cycle operated in the past. Inclusions in diamonds, which remain uncorrupted over geological times, may instead provide direct records of deep Earth’s evolution. Here, we applied elastic geothermobarometry to a diamond-magnesiochromite (mchr) host-inclusion pair from the Udachnaya kimberlite (Siberia, Russia), one of the most important sources of natural diamonds. By combining X-ray diffraction and Fourier-transform infrared spectroscopy data with a new elastic model, we obtained entrapment conditions, Ptrap = 6.5(2) GPa and Ttrap = 1125(32)–1140(33) °C, for the mchr inclusion. These conditions fall on a ca. 35 mW/m2 geotherm and are colder than the great majority of mantle xenoliths from similar depth in the same kimberlite. Our results indicate that cold cratonic conditions persisted for billions of years to at least 200 km in the local lithosphere. The composition of the mchr also indicates that at this depth the lithosphere was, at least locally, ultra-depleted at the time of diamond formation, as opposed to the melt-metasomatized, enriched composition of most xenoliths

T. brucei Infection Reduces B Lymphopoiesis in Bone Marrow and Truncates Compensatory Splenic Lymphopoiesis through Transitional B-Cell Apoptosis

African trypanosomes of the Trypanosoma brucei species are extracellular protozoan parasites that cause the deadly disease African trypanosomiasis in humans and contribute to the animal counterpart, Nagana. Trypanosome clearance from the bloodstream is mediated by antibodies specific for their Variant Surface Glycoprotein (VSG) coat antigens. However, T. brucei infection induces polyclonal B cell activation, B cell clonal exhaustion, sustained depletion of mature splenic Marginal Zone B (MZB) and Follicular B (FoB) cells, and destruction of the B-cell memory compartment. To determine how trypanosome infection compromises the humoral immune defense system we used a C57BL/6 T. brucei AnTat 1.1 mouse model and multicolor flow cytometry to document B cell development and maturation during infection. Our results show a more than 95% reduction in B cell precursor numbers from the CLP, pre-pro-B, pro-B, pre-B and immature B cell stages in the bone marrow. In the spleen, T. brucei induces extramedullary B lymphopoiesis as evidenced by significant increases in HSC-LMPP, CLP, pre-pro-B, pro-B and pre-B cell populations. However, final B cell maturation is abrogated by infection-induced apoptosis of transitional B cells of both the T1 and T2 populations which is not uniquely dependent on TNF-, Fas-, or prostaglandin-dependent death pathways. Results obtained from ex vivo co-cultures of living bloodstream form trypanosomes and splenocytes demonstrate that trypanosome surface coat-dependent contact with T1/2 B cells triggers their deletion. We conclude that infection-induced and possibly parasite-contact dependent deletion of transitional B cells prevents replenishment of mature B cell compartments during infection thus contributing to a loss of the host's capacity to sustain antibody responses against recurring parasitemic waves

Effects of Spanwise-Discontinuous Contoured Transverse Grooves on Flow Separation and Vortex Shedding

The delay of boundary layer separation over curved solid surfaces is of great importance in many engineering applications. The proposed idea is to introduce small and suitably shaped grooves transverse to the flow (i.e., contoured transverse grooves) to passively generate local steady flow recirculations

Spanwise-Discontinuous Grooves for Separation Delay and Drag Reduction of Bodies with Vortex Shedding

Suitably shaped grooves, placed transverse to the flow, can delay flow separation over curved surfaces. When grooves are fully extruded in the spanwise direction, they may reduce the drag of boat-tailed bodies with vortex shedding, but with the drawback of increasing the spanwise correlation of the vortex shedding. We investigate herein the effect of spanwise-discontinuous grooves through Large Eddy Simulations. A systematic analysis is carried out on the effect of the number, N, of grooves that are present for N equally long portions of the total spanwise length of the boat-tail. Discontinuous grooves further reduce the drag compared with the full-spanwise-extruded groove. Increasing N produces an improvement of the flow-control-device performance, whose maximum value is reached for N = 3, corresponding to a spanwise extension of the groove roughly equal to the body crossflow dimension. Above this value, no further improvements are found. The maximum drag reduction is equal to 25.7% of the drag of the boat-tail without grooves and to 17.7% of the one of the boat-tail with the full-spanwise-extruded groove. The lowest drag value occurs for the least correlated vortex-shedding in the spanwise direction. The reduction in the correlation is mainly related to a flow separation line that is less regular in the spanwise direction

Effect of the Lateral Mean Recirculation Characteristics on Near-Wake and Bulk Quantities of a 5:1 Rectangular Cylinder

A database of several LES carried out for the high-Reynolds number flow around a 5:1 rectangular cylinder is analyzed to highlight the effects of the characteristics of the mean flow over the cylinder side on the near-wake features and on some bulk quantities. Different simulation set-ups are considered by varying the grid refinement in the spanwise direction and the amount of SGS dissipation for sharp upstream edges and with different values of the upstream-edge rounding. These simulations may be considered as possible instances of this kind of flow with different mean flow features on the cylinder side. Among the different characteristic lengths defining the mean recirculation, the streamwise length is the most important parameter. The wake width increases linearly with this parameter, while the vortex-shedding non-dimensional frequency shows a linear decrease. The drag coefficient also linearly decreases with increasing the recirculation length and this is due to a reduction of the suctions on the cylinder base. However, the overall variation of CD is small. Finally, a significant, and once again linear, increase of the fluctuations of the lift coefficient is found for increasing the mean recirculation streamwise length