Ferromagnetic interlayer coupling in FeSe1−xSx superconductors revealed by inelastic neutron scattering

FeSe1-xSx superconductors are commonly considered layered van der Waals materials with negligible interlayer coupling. Here, using inelastic neutron scattering to study spin excitations in single-crystal samples, we reveal that the magnetic coupling between adjacent Fe layers is ferromagnetic in nature, making the system different from most unconventional superconductors including iron pnictides. The weak interlayer coupling is estimated to be Jc∼ 0.2 meV, in agreement with the short spin-spin correlation length ζc∼0.2c along the c axis. The results provide an experimental basis for establishing a microscopic theoretical model to describe the absence of magnetic order in FeSe1-xSx

Plants changed the response of bacterial community to the nitrogen and phosphorus addition ratio

IntroductionHuman activities have increased the nitrogen (N) and phosphorus (P) supply ratio of the natural ecosystem, which affects the growth of plants and the circulation of soil nutrients. However, the effect of the N and P supply ratio and the effect of plant on the soil microbial community are still unclear.MethodsIn this study, 16s rRNA sequencing was used to characterize the response of bacterial communities in Phragmites communis (P.communis) rhizosphere and non-rhizosphere soil to N and P addition ratio.ResultsThe results showed that the a-diversity of the P.communis rhizosphere soil bacterial community increased with increasing N and P addition ratio, which was caused by the increased salt and microbially available C content by the N and P ratio. N and P addition ratio decreased the pH of non-rhizosphere soil, which consequently decreased the a-diversity of the bacterial community. With increasing N and P addition ratio, the relative abundance of Proteobacteria and Bacteroidetes increased, while that of Actinobacteria and Acidobacteria decreased, which reflected the trophic strategy of the bacterial community. The bacterial community composition of the non-rhizosphere soil was significantly affected by salt, pH and total carbon (TC) content. Salt limited the relative abundance of Actinobacteria, and increased the relative abundance of Bacteroidetes. The symbiotic network of the rhizosphere soil bacterial community had lower robustness. This is attributed to the greater selective effect of plants on the bacterial community influenced by nutrient addition.DiscussionPlants played a regulatory role in the process of N and P addition affecting the bacterial community, and nutrient uptake by the root system reduced the negative impact of N and P addition on the bacterial community. The variations in the rhizosphere soil bacterial community were mainly caused by the response of the plant to the N and P addition ratio

Root growth characteristics and antioxidant system of Suaeda salsa in response to the short-term nitrogen and phosphorus addition in the Yellow River Delta

Human activities have increased nitrogen (N) and phosphorus (P) inputs to the Yellow River Delta and the supply level of N and P affects plant growth as well as ecosystem structure and function directly. However, the root growth, stoichiometry, and antioxidant system of plants in response to N and P additions, especially for herbaceous halophyte in the Yellow River Delta (YRD), remain unknown. A field experiment with N addition (0, 5, 15, and 45 g N m-2 yr-1, respectively) as the main plot, and P addition (0 and 1 g N m-2 yr-1, respectively) as the subplot, was carried out with a split-plot design to investigate the effects on the root morphology, stoichiometry, and antioxidant system of Suaeda salsa. The results showed that N addition significantly increased the above-ground and root biomass as well as shoot-root ratio of S. salsa, which had a significant interaction with P addition. The highest biomass was found in the treatment with 45 g N m-2 yr-1 combined with P addition. N addition significantly increased TN content and decreased C:N ratio of root, while P addition significantly increased TP content and decreased C:P ratio. The main root length (MRL), total root length (TRL), specific root length (SRL), and root tissue density (RTD) of S. salsa root were significantly affected by N addition and P addition, as well as their interaction. The treatments with or without P addition at the 45 g N m-2 yr-1 of N addition significantly increased the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities and soluble protein content of roots, decreased malondialdehyde (MDA) content. And there was a significant interaction between the N and P addition on SOD activity. Therefore, N and P additions could improve the growth of S. salsa by altering the root morphology, increasing the root nutrient content, and stimulating antioxidant system

Advances in the Mechanism and Regulation of Obesity Induced by Gut Microbiota

The global prevalence of obesity has nearly tripled in the past 40 years and continues to rise at an alarming rate. High fat and high carbohydrate diets can cause gut microbiota disturbance and impairment of intestinal barrier function in obese individuals. Dysbiosis of the gut microbiota and its metabolites crossing the intestinal barrier lead to insulin resistance, imbalance in energy metabolism, reduced fat browning capacity and increased levels of inflammatory factors, which in turn induce chronic diseases such as diabetes, hypertension and cardiovascular diseases. In this paper, the molecular mechanism of obesity mediated by the gut microbiota is systematically elucidated. Based on this, we propose that the intestinal microecology can be regulated by supplementing probiotics and prebiotics or by changing lifestyle and dietary pattern, which in turn will help to prevent and control obesity

Anodic Oxidation Synthesis of One-Dimensional TiO 2

One-dimensional (1D) TiO2 micro/nanostructures have received more and more attentions because of their potential applications in environmental issues. This paper reviews the most recent activities in TiO2 nanostructures with an emphasis on the authors’ own results especially on those synthesized using anodic oxidation method. The review begins with a survey of the effects of fabrication methods and the experiment conditions on the obtained TiO2 nanostructures, and then focuses on their 1D nanostructures, including the syntheses, characterizations, formation mechanisms, photocatalytic, and field emission properties. Finally, we conclude this review with the perspectives and outlooks on the future developments in this field

Ferromagnetic inter-layer coupling in FeSe1−x_{1-x}Sx_{x} superconductors revealed by inelastic neutron scattering

FeSe$_{1-x}$S$_{x}$ superconductors are commonly considered layered van der Waals materials with negligible inter-layer coupling. Here, using inelastic neutron scattering to study spin excitations in single-crystal samples, we reveal that the magnetic coupling between adjacent Fe layers is not only significant, as it affects excitations up to \textcolor{black}{15} meV, but also ferromagnetic in nature, making the system different from most unconventional superconductors including iron pnictides. Our observation provides a new standpoint to understand the absence of magnetic order in FeSe$_{1-x}$S$_{x}$. Since intercalating between the Fe layers is known to enhance superconductivity and suppress the inter-layer coupling, superconductivity appears to be a more robust phenomenon in the two-dimensional limit than antiferromagnetic order