Mini volume collapse as evidence for a three-body magnetic polaron in S m1-x e ux S

Samarium sulfide (SmS) is a nonmagnetic narrow-gap (0.06 eV) semiconductor that undergoes a transition to a metallic intermediate valence state at 6.5 kbar. Europium sulfide (EuS) is a ferromagnetic semiconductor with a Curie temperature of 16 K and a gap of 1.6 eV. Here we present a study of the lattice constant, magnetic susceptibility, and resistivity of the substitution series Sm1-xEuxS for 0 \u3c x \u3c 1. We observe a smooth interpolation of magnetic and transport behavior across the series, consistent with a virtual crystal scenario and Vegard\u27s law. Surprisingly, however, the lattice constant deviates below Vegard\u27s law in a manner that suggests parametric control of the Sm-Sm distance by the Eu moment in the manner of a magnetic polaron

Gene expression during bacterivorous growth of a widespread marine heterotrophic flagellate

Phagocytosis is a fundamental process in marine ecosystems by which prey organisms are consumed and their biomass incorporated in food webs or remineralized. However, studies searching for the genes underlying this key ecological process in free-living phagocytizing protists are still scarce, in part due to the lack of appropriate ecological models. Our reanalysis of recent molecular datasets revealed that the cultured heterotrophic flagellate Cafeteria burkhardae is widespread in the global oceans, which prompted us to design a transcriptomics study with this species, grown with the cultured flavobacterium Dokdonia sp. We compared the gene expression between exponential and stationary phases, which were complemented with three starvation by dilution phases that appeared as intermediate states. We found distinct expression profiles in each condition and identified 2056 differentially expressed genes between exponential and stationary samples. Upregulated genes at the exponential phase were related to DNA duplication, transcription and translational machinery, protein remodeling, respiration and phagocytosis, whereas upregulated genes in the stationary phase were involved in signal transduction, cell adhesion, and lipid metabolism. We identified a few highly expressed phagocytosis genes, like peptidases and proton pumps, which could be used to target this ecologically relevant process in marine ecosystems

Inhibition of vascular calcification by inositol phosphates derivatized with ethylene glycol oligomers

Myo-inositol hexakisphosphate (IP6) is a natural product known to inhibit vascular calcification (VC), but with limited potency and low plasma exposure following bolus administration. Here we report the design of a series of inositol phosphate analogs as crystallization inhibitors, among which 4,6-di-O-(methoxy-diethyleneglycol)-myo-inositol-1,2,3,5-tetrakis(phosphate), (OEG <sub>2</sub> ) <sub>2</sub> -IP4, displays increased in vitro activity, as well as more favorable pharmacokinetic and safety profiles than IP6 after subcutaneous injection. (OEG <sub>2</sub> ) <sub>2</sub> -IP4 potently stabilizes calciprotein particle (CPP) growth, consistently demonstrates low micromolar activity in different in vitro models of VC (i.e., human serum, primary cell cultures, and tissue explants), and largely abolishes the development of VC in rodent models, while not causing toxicity related to serum calcium chelation. The data suggest a mechanism of action independent of the etiology of VC, whereby (OEG <sub>2</sub> ) <sub>2</sub> -IP4 disrupts the nucleation and growth of pathological calcification

Observation of Quantum Oscillations in The Low Temperature Specific Heat of SmB\u3csub\u3e6\u3c/sub\u3e

We report measurements of the low-temperature specific heat of Al-flux-grown samples of SmB6 in magnetic fields up to 32 T. Quantum oscillations periodic in \emph{1/H} are observed between 8 and 32 T at selected angles between [001] and [111]. The observed frequencies and their angular dependence are consistent with previous magnetic torque measurements of SmB6 but the effective masses inferred from Lifshitz-Kosevich theory are significantly larger and closer to those inferred from zero-field specific heat. Our results are thus consistent with a bulk density of states origin for the previously observed quantum oscillations

A new similar to 900-year varved record in Lake Walker, Quebec North Shore, eastern Canada : insight on late Holocene climate mode of variability

This paper presents a new annually laminated record (varves) from Lake Walker, Quebec North Shore (eastern Canada) spanning the period from similar to 3230 to 2320 +/- 20 cal BP. A similar to 3.5-m-long composite sequence was established with the best regular and continuous laminated intervals using computed tomography and high-resolution photographs. The varve chronology was built based on two methods: manual multi-parameter counting using the PeakCounter software, and manual counting on thin-section images obtained by scanning electron microscopy (SEM). The latter correlates more closely with the ages derived from AMS radiocarbon dating, suggesting that thin-section analysis is here a more reliable counting technique. Varves are clastic, composed of a silt layer deposited in spring and summer, and a clay layer deposited in winter. Annually resolved grain size obtained using image analysis technique on SEM images of thin sections and elemental composition from X-ray microfluorescence analyses performed on the floating varve chronology suggests that the record is sensitive to the North Atlantic Oscillation (NAO), as revealed by the strong co-variability with another lower resolution record from Greenland. This suggests that periods of negative winter NAO promoted a thicker snow cover that resulted in higher river discharges and stronger clastic component in the varves. In modern times, cooling of the North Atlantic in the mid 1970s to the late 1980s was also characterized by concurrent negative phase of NAO, which condition translated into increase snow precipitation over the region. Overall, these results highlight that the new Lake Walker varve record presents remarkable prospects of developing a longer and high-resolution paleoclimatological reconstruction of the NAO in a region where similar records are scarce

Pichia pastoris is a valuable host for the expression of genes encoding membrane proteins from the hyperthermophilic Archeon Pyrococcus abyssi

We present here the experimental strategies, first results and identified bottlenecks of a structural genomics initiative on membrane proteins of the hyperthermophilic archaea Pyrococcus abyssi. Five ORFs coding for putative membrane proteins have been cloned and expressed in the methylotrophic Pichia pastoris expression system, using two different constructs, with or without the signal sequence alpha-mating factor of Saccharomyces cerevisiae. A c-myc epitope and 6 His codons were added at the 3'-end of the targeted genes to allow immunodetection of the recombinant proteins and to facilitate their further purification. We have selected at least one producer clone for each protein of interest and for almost every construction. All the membrane proteins were produced in Erlenmeyer flasks culture and in fed-batch cultivation for large-scale preparation. The proteins were detected in the membrane fractions of P. pastoris. Production efficiencies were relatively low in both production conditions but the quantities of biomass obtained during fed-batch cultivation have allowed us to collect sufficient amount of material for further purification. The proteins were extracted, solubilized and partially purified. Large-scale purification will be necessary for further structural work