Shallow-terrace-like interface in dilute-bismuth GaSb/AlGaSb single quantum wells evidenced by photoluminescence

Photoluminescence (PL) measurements are performed on one GaSb/AlGaSb single-quantum-well (SQW) sample and two dilute-bismuth (Bi) GaSb/AlGaSb SQW samples grown at 360 and 380 °C, at low temperatures and under magnetic fields. Bimodal PL features are identified in the dilute-Bi samples, and to be accompanied by abnormal PL blueshift in the sample grown at 360 °C. The bimodal PL features are found to be from similar origins of band-to-band transition by magneto-PL evolution. Analysis indicates that the phenomenon can be well interpreted by the joint effect of interfacial large-lateral-scale islands and Al/Ga interdiffusion due to Bi incorporation. The interdiffusion introduces about 1-monolayer shrinkage to the effective quantum-well thickness, which is similar to the interfacial islands height, and the both together result in an unusual shallow-terrace-like interface between GaSbBi and AlGaSb. A phenomenological model is established, the Bi content of isoelectronic incorporation and the exciton reduced effective mass are estimated for the GaSbBi sample grown at 380 °C, and a value of about 21 meV/% is suggested for the bandgap bowing rate of GaSbBi. An effective routine is suggested for determining the Bi content and the depth of the shallow-terraces at interface in dilute-Bi SQW structures

Investigation of the kinetics and mechanism of the glycerol chlorination reaction using gas chromatography–mass spectrometry

As a primary by-product in biodiesel production, glycerol can be used to prepare an important fine chemical, epichlorohydrin, by the glycerol chlorination reaction. Although this process has been applied in industrial production, unfortunately, less attention has been paid to the analysis and separation of the compounds in the glycerol chlorination products. In this study, a convenient and accurate method to determine the products in glycerol chlorination reaction was established and based on the results the kinetic mechanism of the reaction was investigated. The structure of main products, including 1,3--dichloropropan-2-ol, 2,3-dichloropropan-1-ol, 3-chloro-1,2-propanediol, 2-chloro-1,3-propanediol and glycerol was ascertained by gas chromatography–mass spectrometry and the isomers of the products were distinguished. Apidic acid was considered as the best catalyst because of its excellent catalytic effect and high boiling point. The mechanism of the glycerol chlorination reaction was proposed and a new kinetic model was developed. Kinetic equations of the process in the experimental range were obtained by data fitting and the activation energies of each tandem reaction were 30.7, 41.8, 29.4 and 49.5 kJ mol-1, respectively. This study revealed the process and mechanism of the kinetics and provides the theoretical basis for engineering problems

Dual Correlation Network for Efficient Video Semantic Segmentation

Video data bring a big challenge to semantic segmentation due to the large volume of data and strong inter-frame redundancy. In this paper, we propose a dual local and global correlation network tailored for efficient video semantic segmentation. It consists of three modules: 1) a local attention based module, which measures correlation and achieves feature aggregation in a local region between key frame and non-key frame; 2) a consistent constraint module, which considers long-range correlation among pixels from a global view for promoting intra-frame semantic consistency of non-key frame; and 3) a key frame decision module, which selects key frames adaptively based on the ability of feature transferring. Extensive experiments on the Cityscapes and Camvid video datasets demonstrate that our proposed method could reduce inference time significantly while maintaining high accuracy. The implementation is available at https://github.com/An01168/DCNVSS

Study on the collaborative protective mechanism of Scutellariae Radix and Paeoniae Radix Alba against diabetic cardiomyopathy through the gut-heart axis

The modification of gut microbiota has been linked to diabetic cardiomyopathy, yet the precise mechanisms through which gut microbes impact cardiac injury remain unclear. Our study concentrated on the gut microorganisms, the intestinal mucosal barrier, and the metabolic pathways involving glucose and lipids in mice afflicted with diabetic cardiomyopathy, while also investigating the cardioprotective properties of Scutellariae Radix and Paeoniae Radix Alba. Using a db (Leptin receptor gene-deficient mouse) mouse model of diabetic cardiomyopathy, we observed that these mice exhibited a decline in the diversity of intestinal microbes, alterations in the abundance of diabetes-related microorganisms, a decrease in Firmicutes, an increase in Helicobacter, and an overall rise in intestinal microbial populations. We pinpointed the inflammatory response and the compromised permeability of the intestinal lining as key contributors to the decline of the intestinal mucosal barrier, subsequently leading to cardiac injury. Administering Scutellariae Radix and Paeoniae Radix Alba was shown to restore the equilibrium of the intestinal microbiota, modify metabolic pathways involving glycerophospholipids, arachidonic acid, and additional metabolites within the myocardial tissue through bile acid, taurine, and associated metabolic processes, resulting in lessened cardiac dysfunction, hypertrophy, and fibrosis in the diabetic cardiomyopathy mice. In conclusion, our findings indicate that the intestinal microbiota, intestinal mucosal barrier, and glycolipid metabolism are disrupted in mice with diabetic cardiomyopathy; however, Scutellariae Radix and Paeoniae Radix Alba may effectively reverse these alterations. These results offer valuable insights for creating therapeutic strategies aimed at mitigating cardiac damage linked to diabetes by focusing on the gut microbiota and glucose and lipid metabolism

Ferroelectric polymer nanopillar arrays on flexible substrates by reverse nanoimprint lithography

With the increasing interest in deploying ferroelectric polymer in flexible electronics and electromechanics, high-throughput and low-cost fabrication of 3D ferroelectric polymer nanostructures on flexible substrates can be a significant basis for future research and applications. Here, we report that large arrays of ferroelectric polymer nanopillars can be prepared directly on soft, flexible substrates by using low-cost polydimethylsiloxane (PDMS) soft-mold reverse nanoimprint lithography at 135 °C and at pressures as low as 3 bar. The nanopillar arrays were highly uniform over large areas of at least 200 × 200 μm and had good crystallinity with nearly optimum (110) orientation. Furthermore, the method leaves little or no residual polymer layer, fully isolating the nanopillars to avoid cross-talk and, obviating the need for additional etching processes that arises with conventional low-contrast nanoimprinting. The ferroelectric properties of individual nanopillars were probed by piezoresponse force microscopy, which showed that they exhibited switchable and bi-stable polarization. In addition, the polarization hysteresis loops probed by pyroelectric measurements of the entire array showed that the nanopillar capacitor arrays had good ferroelectric switching characteristics, over areas of at least 1 mm × 1 mm