Staircase-like metamagnetic transitions in phase-separated manganites: influence of thermal and mechanical treatments

Substitutions in the Mn-sublattice of antiferromagnetic, charge and orbitally ordered manganites was recently found to produce intriguing metamagnetic transitions, consisting of a succession of sharp magnetization steps separated by plateaus. The compounds exhibiting such features can be divided in two categories, depending on whether they are sensitive to thermal cycling effects or not. One compound of each category has been considered in the present study. The paper reports on the influence of two treatments: high-temperature annealing and grinding. It is shown that both of these treatments can drastically affect the phenomenon of magnetization steps. These results provide us with new information about the origin of these jumps in magnetization.Comment: accepted for publication in J.Appl.Phy

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Large Oxygen Nonstoichiometry in La_0.77Sr_3.23Co_2.75C_0.25O_8.40+δ Oxide (δ = 0, 1.3) Related to <i>n</i> = 3 RP Series

An original Ruddlesden–Popper phase, La_0.77Sr_3.23Co_2.75C_0.25O_8.40+δ, was isolated and studied by electron, X-ray, and neutron diffraction. This structure has complex crystal chemistry resulting from a high degree of flexibility in the structure, comprising the disordered introduction of carbonates into a cobalt layer and an important oxygen deficiency with a preferential repartition of vacancies along the layers stacking sequence. The former is necessary for the stabilization of the system, while the latter can be tuned by postsynthetic treatment, yielding in a large variety of cobalt species formal oxidation states ranging from Co²⁺/Co³⁺ in the as-made phase to Co³⁺/Co⁴⁺ when annealed under oxygen pressure. The potential richness deriving from this flexibility is illustrated in terms of the magnetotransport properties and includes a resistivity that varies within a range of 5 orders of magnitude after modulation of the oxygen content with the appearance of negative magnetoresistance and ferromagnetic interactions due to Co³⁺/Co⁴⁺ mixed-valence state

Large Oxygen Nonstoichiometry in La_0.77Sr_3.23Co_2.75C_0.25O_8.40+δ Oxide (δ = 0, 1.3) Related to <i>n</i> = 3 RP Series

An original Ruddlesden–Popper phase, La_0.77Sr_3.23Co_2.75C_0.25O_8.40+δ, was isolated and studied by electron, X-ray, and neutron diffraction. This structure has complex crystal chemistry resulting from a high degree of flexibility in the structure, comprising the disordered introduction of carbonates into a cobalt layer and an important oxygen deficiency with a preferential repartition of vacancies along the layers stacking sequence. The former is necessary for the stabilization of the system, while the latter can be tuned by postsynthetic treatment, yielding in a large variety of cobalt species formal oxidation states ranging from Co²⁺/Co³⁺ in the as-made phase to Co³⁺/Co⁴⁺ when annealed under oxygen pressure. The potential richness deriving from this flexibility is illustrated in terms of the magnetotransport properties and includes a resistivity that varies within a range of 5 orders of magnitude after modulation of the oxygen content with the appearance of negative magnetoresistance and ferromagnetic interactions due to Co³⁺/Co⁴⁺ mixed-valence state

Isolation and Characterization of a Slowly Milk-Coagulating Variant of Lactobacillus helveticus Deficient in Purine Biosynthesis

A slowly milk-coagulating variant (Fmc(−)) of Lactobacillus helveticus CRL 1062, designated S1, was isolated and characterized. Strain S1 possessed all the known essential components required to utilize casein as a nitrogen source, which include functional proteinase and peptidase activities as well as functional amino acid, di- and tripeptide, and oligopeptide transport systems. The amino acid requirements of strain S1 were similar to those of the parental strain. However, on a purine-free, chemically defined medium, the growth rate of the Fmc(−) strain was threefold lower than that of the wild-type strain. L. helveticus S1 was found to be defective in IMP dehydrogenase activity and therefore was deficient in the ability to synthesize XMP and GMP. This conclusion was further supported by the observation that the addition of guanine or xanthine to milk, a substrate poor in purine compounds, restored the Fmc(+) phenotype of L. helveticus S1

Large Oxygen Nonstoichiometry in La_0.77Sr_3.23Co_2.75C_0.25O_8.40+δ Oxide (δ = 0, 1.3) Related to <i>n</i> = 3 RP Series

An original Ruddlesden–Popper phase, La_0.77Sr_3.23Co_2.75C_0.25O_8.40+δ, was isolated and studied by electron, X-ray, and neutron diffraction. This structure has complex crystal chemistry resulting from a high degree of flexibility in the structure, comprising the disordered introduction of carbonates into a cobalt layer and an important oxygen deficiency with a preferential repartition of vacancies along the layers stacking sequence. The former is necessary for the stabilization of the system, while the latter can be tuned by postsynthetic treatment, yielding in a large variety of cobalt species formal oxidation states ranging from Co²⁺/Co³⁺ in the as-made phase to Co³⁺/Co⁴⁺ when annealed under oxygen pressure. The potential richness deriving from this flexibility is illustrated in terms of the magnetotransport properties and includes a resistivity that varies within a range of 5 orders of magnitude after modulation of the oxygen content with the appearance of negative magnetoresistance and ferromagnetic interactions due to Co³⁺/Co⁴⁺ mixed-valence state

Sr₇Co₄(CO₃)O_13−δ (δ = 1.64), An Original Cobaltite Derivative of the Ruddlesden–Popper Series

The oxycarbonate Sr₇Co₄(CO₃)­O_11.36 exhibits a peculiar structure that has been characterized by combining transmission electron microscopy analyses and neutron diffraction. It consists of a regular intergrowth between the <i>m</i> = 2 and carbonated <i>m</i> = 3 members of the Sr_<i>m</i>+1Co_<i>m</i>O_3<i>m</i>+1 Ruddlesden–Popper (RP) series, Sr₃Co₂O_5.87 and Sr₄Co₂(CO₃)­O_5.49, respectively. A description of the structure is proposed to provide identification of the different building blocks. This material is semiconducting and presents a complex magnetic behavior, characteristic of what is observed for the RP² or RP³ series, with a cobalt valency close to 2.7

Synthesis of Antimonene on Germanium

The lack of large-area synthesis processes on substrates compatible with industry requirements has been one of the major hurdles facing the integration of 2D materials in mainstream technologies. This is particularly the case for the recently discovered monoelemental group V 2D materials which can only be produced by exfoliation or growth on exotic substrates. Herein, to overcome this limitation, we demonstrate a scalable method to synthesize antimonene on germanium substrates using solid-source molecular beam epitaxy. This emerging 2D material has been attracting a great deal of attention due to its high environmental stability and its outstanding optical and electronic properties. In situ low energy electron microscopy allowed the real time investigation and optimization of the 2D growth. Theoretical calculations combined with atomic-scale microscopic and spectroscopic measurements demonstrated that the grown antimonene sheets are of high crystalline quality, interact weakly with germanium, exhibit semimetallic characteristics, and remain stable under ambient conditions. This achievement paves the way for the integration of antimonene in innovative nanoscale and quantum technologies compatible with the current semiconductor manufacturing

A New Dietary Inflammatory Index Predicts Interval Changes in Serum High-Sensitivity C-Reactive Protein1–3

Inflammation is associated with a number of chronic conditions, such as cancer and cardiovascular disease. Reducing inflammation may help prevent or treat these conditions. Diet has consistently been shown to modulate inflammation. To facilitate research into the inflammatory effect of diet on health in humans, we sought to develop and validate an Inflammatory Index designed to assess the inflammatory potential of individuals' diets. An Inflammatory Index was developed based on the results of an extensive literature search. Using data from a longitudinal observational study that carefully measured diet and the inflammatory marker, serum high-sensitivity (hs) C-reactive protein (CRP), in ∼600 adults for 1 y, we conducted analyses to test the effect of Inflammatory Index score on hs-CRP as a continuous and dichotomous (≤3 mg/L, >3 mg/L) indicator of inflammatory response, while controlling for important potential confounders. Results based on continuous measures of hs-CRP suggested that an increasing Inflammatory Index score (representing movement toward an antiinflammatory diet) was associated with a decrease in hs-CRP. Analyses using hs-CRP as a dichotomous variable showed that an antiinflammatory diet was associated with a decrease in the odds of an elevated hs-CRP (P = 0.049). The results are consistent with the ability of the Inflammatory Index to predict hs-CRP and provide additional evidence that diet plays a role in the regulation of inflammation, even after careful control of a wide variety of potential confounders