New two-dimensional flat band materials: B3C11O6 and B3C15O6.

Recently, there has been growing interest in the field of flat-band physics due to its attractive properties and wide range of practical applications. In this study, we introduce two novel two-dimensional monolayers, namely B3C11O6 and B3C15O6, which exhibit a flat band near the Fermi level. These monolayers have been found to be energetically favorable, dynamically stable, and thermodynamically stable based on formation energies, phonon spectra, and molecular dynamics simulations. The nearly flat band (NFB) in B3C11O6 arises from the extended kagome sublattice of carbon atoms. Due to the strong interaction between carbon atoms beyond their nearest neighbors, the bandwidth of the initial flat band is extended to approximately 0.5 eV. Nevertheless, there is still a prominent peak in the density of states near the Fermi level. On the other hand, the NFB in B3C15O6 originates from the localized states of the carbon five-ring structure, which forms a distorted kagome lattice. The presence and characteristics of the NFB strongly depend on the interactions between next-nearest neighbors. Interestingly, the partially occupied NFB in B3C11O6 leads to spin splitting, resulting in a transformation of the system into a ferromagnetic metal. Our research not only presents two types of lattices capable of hosting flat bands or NFBs, but also provides two monolayers that can be employed to investigate various intriguing quantum phases.

Ferroelastic-switching-driven large shear strain and piezoelectricity in a hybrid ferroelectric.

Materials that can produce large controllable strains are widely used in shape memory devices, actuators and sensors1,2, and great efforts have been made to improve the strain output3-6. Among them, ferroelastic transitions underpin giant reversible strains in electrically driven ferroelectrics or piezoelectrics and thermally or magnetically driven shape memory alloys7,8. However, large-strain ferroelastic switching in conventional ferroelectrics is very challenging, while magnetic and thermal controls are not desirable for practical applications. Here we demonstrate a large shear strain of up to 21.5% in a hybrid ferroelectric, C6H5N(CH3)3CdCl3, which is two orders of magnitude greater than that in conventional ferroelectric polymers and oxides. It is achieved by inorganic bond switching and facilitated by structural confinement of the large organic moieties, which prevents undesired 180° polarization switching. Furthermore, Br substitution can soften the bonds, allowing a sizable shear piezoelectric coefficient (d35 ≈ 4,830 pm V-1) at the Br-rich end of the solid solution, C6H5N(CH3)3CdBr3xCl3(1-x). The electromechanical properties of these compounds suggest their potential in lightweight and high-energy-density devices, and the strategy described here could inspire the development of next-generation piezoelectrics and electroactive materials based on hybrid ferroelectrics.

Application of a novel artificial neural network model in flood forecasting.

In this paper, a novel ANN flood forecasting model is proposed. The ANN model is combined with traditional hydrological concepts and methods, taking the initial Antecedent Precipitation Index (API), rainfall, upstream inflow and initial flow at the forecast river section as input of model, and flood flow forecast of the next time steps as output of the model. The distributed rainfall is realized as the input of the model. The simulation is processed by dividing the watershed into several rainfall-runoff processing units. Two hidden layers are used in the ANN, and the topology of ANN is optimized by connecting the hidden layer neurons only with the input which has physical conceptual causes. The topological structure of the proposed ANN model and its information transmission process are more consistent with the physical conception of rainfall-runoff, and the weight parameters of the model are reduced. The arithmetic moving-average algorithm is added to the output of the model to simulate the pondage action of the watershed. Satisfactory results have been achieved in the Mozitan and Xianghongdian reservoirs in the upper reaches of Pi river in Huaihe Basin, and the Fengman reservoir in the upper reach of Second Songhua river in Songhua basin in China.

Draconibacterium mangrovi sp. nov., isolated from mangrove sediment.

A marine bacterial strain, designated GM2-18T, was isolated from mangrove sediment sampled at Luoyang River estuary, Quanzhou, PR China. Cells were Gram-stain-negative, slightly curved long rod-shaped and facultatively anaerobic with no flagellum. Catalase activity was found to be weak-positive and oxidase-positive. It had no ability to degrade or hydrolyse substrates including skimmed milk, cellulose, starch and Tweens (40, 60 and 80). The 16S rRNA gene sequence of strain GM2-18T had maximum similarity values to 'Draconibacterium filum' F2T, Draconibacterium sediminis JN14CK-3T and Draconibacterium orientale FH5T of 98.0, 97.8 and 97.4 %, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GM2-18T was affiliated to the genus Draconibacterium and formed a clade with an uncultured bacterium clone identified from mangrove environment. Average nucleotide identity values and DNA-DNA hybridization estimates of strain GM2-18T compared to its Draconibacterium relatives strongly supported that it belonged to a new species. The respiratory quinone was menaquinone MK-7. The major fatty acids (>10 %) consisted of iso-C15 : 0, anteiso-C15 : 0 and C17 : 1 ω6c. The polar lipids were phosphatidylethanolamine, a phospholipid and several unidentified lipids. The genomic size of strain GM2-18T was 5.9 Mb and the G+C content was 40.8 mol%. Gene prediction and annotation of strain GM2-18T indicated that there was a nitrogen-fixing gene cluster encoding nitrogenase molybdenum-iron protein and related proteins responsible for nitrogen fixation. Based on the above characteristics, strain GM2-18T represents a novel species within the genus Draconibacterium. Thus, Draconibacterium mangrovi sp. nov. is proposed with type strain GM2-18T (=MCCC 1K04382T=KCTC 72879T), isolated from mangrove sediment.

Molecular Engineering toward Coexistence of Dielectric and Optical Switch Behavior in Hybrid Perovskite Phase Transition Material.

Organic-inorganic hybrid perovskites with considerable dielectric differences near the phase transition are potential candidates as phase transition materials (PTMs). However, compared with traditional PTMs, which require multiple switchable channels, the hybrid perovskites so far show only switching behavior in dielectric constants. We herein report a new crystal design strategy and successful synthesis of a two-dimensional perovskite (C6H5C2H4NH3)2MnCl4. In this hybrid perovskite, the manganese chloride octahedron is a crystal field sensitive luminescent molecular system. The distortion level of MnCl64- also depends on temperature during the order-disorder phase transition. Hence, such a manganese octahedron-based perovskite can exhibit switching behaviors in both dielectric and optical properties. We observe a 14% decrease in optical absorption and 1.6 times increase in dielectric constant during the phase transition at 365 K. In addition, the characteristic photoluminescence decreases by 17% in intensity. Such a molecule-based crystal design paves a new way to explore multifunctional PTMs based on organic-inorganic perovskites.

[Prediction of the side-cut product yield of atmospheric/vacuum distillation unit by NIR crude oil rapid assay].

In the present paper, based on the fast evaluation technique of near infrared, a method to predict the yield of atmos- pheric and vacuum line was developed, combined with H/CAMS software. Firstly, the near-infrared (NIR) spectroscopy method for rapidly determining the true boiling point of crude oil was developed. With commercially available crude oil spectroscopy da- tabase and experiments test from Guangxi Petrochemical Company, calibration model was established and a topological method was used as the calibration. The model can be employed to predict the true boiling point of crude oil. Secondly, the true boiling point based on NIR rapid assay was converted to the side-cut product yield of atmospheric/vacuum distillation unit by H/CAMS software. The predicted yield and the actual yield of distillation product for naphtha, diesel, wax and residual oil were compared in a 7-month period. The result showed that the NIR rapid crude assay can predict the side-cut product yield accurately. The near infrared analytic method for predicting yield has the advantages of fast analysis, reliable results, and being easy to online operate, and it can provide elementary data for refinery planning optimization and crude oil blending.

Motor cortex transcranial magnetic stimulation to reduce intractable postherpetic neuralgia with poor response to other threapies: Report of two cases.

BACKGROUND: Postherpetic neuralgia (PHN) is a typical neuropathic pain condition that appears in the lesioned skin regions following the healing of shingles. The pain condition tends to persist, which is often accompanied by negative emotions (e.g., anxiety and depression) and substantially reduces the quality of life. In addition to analgesia (e.g., pregabalin and gabapentin), nerve radiofrequency technology is an effective treatment for intractable PHN. However, there is still a significant portion of patients who do not benefit from this treatment. As a non-invasive form of brain stimulation, repetitive transcranial magnetic stimulation (rTMS) targeting the motor cortex is able to reduce neuropathic pain with grade A evidence. CASE SUMMARY: Here we report two cases in which motor cortex rTMS was used to treat intractable PHN that did not respond to initial drug and radiofrequency therapies. Moreover, we specifically investigated rTMS efficacy at 3 mo following treatment. CONCLUSION: Motor cortex rTMS can treat intractable PHN that did not respond to initial drug and radiofrequency therapies.

A randomised sham-controlled study evaluating rTMS analgesic efficacy for postherpetic neuralgia.

Context: Postherpetic neuralgia (PHN) is a refractory neuropathic pain condition in which new treatment options are being developed. Repetitive transcranial magnetic stimulation (rTMS) may have the potential to reduce pain sensations in patients with postherpetic neuralgia. Objectives: This study investigated the efficacy on postherpetic neuralgia by stimulating two potential targets, the motor cortex (M1) and the dorsolateral prefrontal cortex (DLPFC). Methods: This is a double-blind, randomised, sham-controlled study. Potential participants were recruited from Hangzhou First People's Hospital. Patients were randomly assigned to either the M1, DLPFC or Sham group. Patients received ten daily sessions of 10-Hz rTMS in 2 consecutive weeks. The primary outcome measure was visual analogue scale (VAS) assessed at baseline, first week of treatment (week 1), post-treatment (week 2), 1-week (week 4), 1-month (week 6) and 3-month (week 14) follow-up. Results: Of sixty patients enrolled, 51 received treatment and completed all outcome assessments. M1 stimulation resulted in a larger analgesia during and after treatment compared to the Sham (week 2 - week 14, p < 0.005), as well as to the DLPFC stimulation (week 1 - week 14, p < 0.05). In addition to pain, sleep disturbance was significantly improved and relieved by targeting either the M1 or the DLPFC (M1: week 4 - week 14, p < 0.01; DLPFC: week 4 - week 14, p < 0.01). Moreover, pain sensations following M1 stimulation uniquely predicted improvement in sleep quality. Conclusion: M1 rTMS is superior to DLPFC stimulation in treating PHN with excellent pain response and long-term analgesia. Meanwhile, M1 and DLPFC stimulation were equally effective in improving sleep quality in PHN. Clinical trial registration: https://www.chictr.org.cn/, identifier ChiCTR2100051963.

Bond engineering of molecular ferroelectrics renders soft and high-performance piezoelectric energy harvesting materials.

Piezoelectric materials convert mechanical stress to electrical energy and thus are widely used in energy harvesting and wearable devices. However, in the piezoelectric family, there are two pairs of properties that improving one of them will generally compromises the other, which limits their applications. The first pair is piezoelectric strain and voltage constant, and the second is piezoelectric performance and mechanical softness. Here, we report a molecular bond weakening strategy to mitigate these issues in organic-inorganic hybrid piezoelectrics. By introduction of large-size halide elements, the metal-halide bonds can be effectively weakened, leading to a softening effect on bond strength and reduction in polarization switching barrier. The obtained solid solution C6H5N(CH3)3CdBr2Cl0.75I0.25 exhibits excellent piezoelectric constants (d33 = 367 pm/V, g33 = 3595 × 10-3 Vm/N), energy harvesting property (power density is 11 W/m2), and superior mechanical softness (0.8 GPa), promising this hybrid as high-performance soft piezoelectrics.

Description of Maribellus sediminis sp. nov., a marine nitrogen-fixing bacterium isolated from sediment of cordgrass and mangrove.

Two marine bacterial strains designated Y2-1-60T and GM1-28 were isolated from sediments of cordgrass and mangrove along the Luoyang estuary in Quanzhou Bay, China, respectively. Both strains were Gram-staining-negative, straight rod-shaped, non-flagellum, facultatively anaerobic, nitrogen-fixing, and did not contain carotenoid pigment. Catalase activities were found to be weak positive and oxidase activities negative. The 16S rRNA gene sequences of the two strains were identical and had maximum similarity of 98.0% with Maribellus luteus XSD2T, and of <94.5% with other species. ANI value (96.9%) and DDH estimate (71.5%) between the two strains supported that they belonged to the same species. ANI value and DDH estimate between the two strains and M. luteus XSD2T was 74.3% and 19.4%, respectively, indicating that they represent a novel species. Phylogenetic analysis based on 16S rRNA gene and phylogenomic analysis indicated that strains Y2-1-60T and GM1-28 formed a monophyletic branch within the genus Maribellus. The respiratory quinone was menaquinone MK-7. The major fatty acid (>10%) consisted of iso-C15:0, and iso-C17:0 3-OH. The polar lipids consisted of phosphatidylethanolamine and several unidentified lipids. The genomic G+C contents were 41.9-42.0mol%. Gene annotation revealed that strains Y2-1-60T and GM1-28 contained a set of nif gene cluster (nifHDKENB) responsible for nitrogen fixation. Based on the above characteristics, strains Y2-1-60T and GM1-28 represent a novel species within the genus Maribellus. Thus, Maribellus sediminis sp. nov. is proposed with type strain Y2-1-60T (=MCCC 1K04285T=KCTC 72884T), isolated from cordgrass sediment and strain GM1-28 (=MCCC 1K04384=KCTC 72880), isolated from mangrove sediment.

The Effect of Simvastatin on Gut Microbiota and Lipid Metabolism in Hyperlipidemic Rats Induced by a High-Fat Diet.

The objective of this study was to investigate the effects of simvastatin (SIM) on lipid metabolism disorders and gut microbiota in high-fat diet-induced hyperlipidemic rats. The obtained results revealed that feeding rats with SIM (20 mg/kg/day) significantly decreased serum lipid level and inhibited hepatic lipid accumulation and steatosis. Histological analysis further indicated that SIM reduced lipid deposition in adipocytes and hepatocytes in comparison with that of the HFD group. The underlying mechanisms of SIM administration against HFD-induced hyperlipidemia were also studied by UPLC-Q-TOF/MS-based liver metabonomics coupled with pathway analysis. Metabolic pathway enrichment analysis of liver metabolites with significant difference in abundance indicated that fatty acids metabolism and amino acid metabolism were the main metabolic pathways altered by SIM administration. Meanwhile, operational taxonomic units (OTUs) analysis revealed that oral administration of SIM altered the composition of gut microbiota, including Ruminococcaceae (OTU960) and Lactobacillus (OTU152), and so on. Furthermore, SIM treatment also regulated the mRNA levels of the genes involved in lipid and cholesterol metabolism. Immunohistochemistry (IHC) analysis of the liver-related proteins (CD36, CYP7A1 and SREBP-1C) showed that oral administration of SIM could regulate the levels of the protein expression related to hepatic lipid metabolism.

In-Plane Ferroelectricity in Thin Flakes of Van der Waals Hybrid Perovskite.

Collective ferroic orders in van der Waals (vdW) crystals are receiving increasing attention in 2D materials research. The interplay between spatial quantum confinement and long-range cooperative phenomena not only broadens the horizon of fundamental physics, but also enables new device paradigms and functionalities built upon vdW heterostructures. Here, the in-plane ferroelectric properties in thin flakes of vdW hybrid perovskite bis(benzylammonium) lead tetrachloride are studied. The ordering of electric dipoles along the layer plane circumvents the depolarization field and preserves the ferroelectricity down to one unit-cell thickness or two vdW layers at room temperature. The superior performance of the electromechanical energy conversion is demonstrated by exploiting its in-plane piezoelectricity. The successful isolation of ferroelectric order in atomically thin vdW hybrid perovskite paves the way for nonvolatile flexible electronic devices with the cross-coupling between strain, charge polarization, and valley degrees of freedom.