Interlayer-coupling-engineerable flat bands in twisted MoSi2N4bilayers.

The two-dimensional layered semiconductor MoSi2N4, which has several advantages including high strength, excellent stability, high hole mobility, and high thermal conductivity, was recently successfully synthesized using chemical vapor deposition. Based on first-principles calculations, we investigate the effects of the twist angle and interlayer distance variation on the electronic properties of twisted bilayer MoSi2N4. The flat bands are absent for twisted bilayer MoSi2N4when the twist angleθis reduced to 3.89°. Taking twisted bilayer MoSi2N4withθof 5.09° as an example, we find that flat bands emerge as the interlayer distance decreases. As the interlayer distance can be effectively modulated by hydrostatic pressure, we propose hydrostatic pressure as a knob for tailoring the flat bands in twisted bilayer MoSi2N4. Our findings provide theoretical support for extending the applications of MoSi2N4in strong correlation physics and superconductivity.

Exchange between Interlayer and Intralayer Exciton in WSe2/WS2 Heterostructure by Interlayer Coupling Engineering.

Because of type-II band alignment, interlayer exciton (IX) is found in a van der Waals (vdW) heterostructure (HS) formed by two monolayers of transition-metal dichalcogenides. Manipulation of IXs is of great importance for excitonic integrated devices. Here, we demonstrate that high pressure and tensile strain can be applied to enhance and reduce interlayer coupling of WSe2/WS2 HS, respectively. High pressure induces the transform of intralayer excitons to IX, while tensile strain leads to the transform of IXs to intralayer excitons. In addition, there is a direct-to-indirect band gap transition of WSe2/WS2 HS. The interlayer distance of WSe2/WS2 HS is reduced under high pressure, but it increased under uniaxial tensile strain from first-principles calculations. The calculated band structures explain well the transformation between interlayer and intralayer excitons of WSe2/WS2 HS. This work demonstrates the exchange of interlayer and intralayer excitons and paves the way to manipulate excitons of HS for excitonic applications.

[Changes and clinical significance of serum level of syndecan-4 protein in patients with chronic congestive heart failure].

OBJECTIVE: To detect serum level of syndecan-4 protein in patients with chronic congestive heart failure (CHF) and investigate its correlation with New York Heart Association (NYHA) class and echocardiographic parameters. METHODS: The concentration of serum syndecan-4 protein was measured by enzyme-linked immunosorbent assay (ELISA) in 40 patients with CHF and 40 healthy controls (NCD), respectively. The parameters such as left ventricle ejection fraction (LVEF), fraction shortening (FS), left ventricle end-diastolic diameter (LVDd), left ventricle end-systolic diameter (LVDs), left ventricle end-diastolic volume (LVEDV) and left ventricle end-systolic volume (LVESV) were detected by echocardiography in 40 patients of CHF. Meanwhile, the patients' cardiac function was graded according to NYHA class. RESULTS: The levels of serum syndecan-4 protein significantly increased in CHF group as compared with control group (P<0.01). In CHF group, as the increased grading of NYHA cardiac function, the levels of serum syndecan-4 protein significantly increased (P<0.05). The more upgraded the NYHA grading, the higher level of serum syndecan-4 protein. In bivariate correlations analysis showed that the level of serum syndecan-4 protein was significantly negatively correlated with LVEF and FS (P<0.05) and was significantly positively correlated with LVDd, LVDs, LVEDV and LVESV, respectively (P<0.05). CONCLUSION: Serum syndecan-4 concentration significantly increased in CHF patients, and it was closely correlated with NYHA class and left ventricle function parameters, so the level of serum syndecan-4 protein may have an important value in detection and surveillance of CHF.

Bioelectrochemical stimulation of petroleum hydrocarbon degradation in saline soil using U-tube microbial fuel cells.

Bioremediation is a cost-effective and eco-friendly approach to decontaminate soils polluted by petroleum hydrocarbons. However, this technique usually requires a long time due to the slow degradation rate by bacteria. By applying U-tube microbial fuel cells (MFCs) designed here, the degradation rate of petroleum hydrocarbons close to the anode (<1 cm) was enhanced by 120% from 6.9 ± 2.5% to 15.2 ± 0.6% with simultaneous 125 ± 7 C of charge output (0.85 ± 0.05 mW/m(2) , 1 kΩ) in the tested period (25 days). Hydrocarbon fingerprint analysis showed that the degradation rate of both alkanes and polycyclic aromatic hydrocarbons (PAHs) was accelerated. The decrease of initial water content from 33% to 28% and 23% resulted in a decrease on charge output and hydrocarbon degradation rate, which could be attributed to the increase of internal resistance. A salt accumulation was observed in each reactor due to the evaporation of water from the air-cathode, possibly inhibited the activity of exoelectrogenic bacteria (EB) and resulted in the elimination of the current at the end of the tested period. The number of hydrocarbon degradation bacteria (HDB) in soil close to the anode increased by nearly two orders of magnitude in the MFC assisted system (373 ± 56 × 10(3) CFU/g-soil) than that in the disconnected control (8 ± 2 × 10(3) CFU/g-soil), providing a solid evidence for in situ biostimulation of HDB growth by colonization of EB in the same system.

Evaluation of cadmium phytoremediation potential in Chinese cabbage cultivars.

Selecting a phytoextraction plant with moderate to high Cd-accumulating ability and high biomass based on the plant's compatibility with mechanized cultivation techniques may yield more immediately practical results. In the present study, six Chinese cabbage cultivars were grown in three soils, ranging from 0.15 to 2.25 mg Cd kg(-1) soil, to examine uptake and translocation of Cd in their tissues. The results indicated that the order of the shoot Cd concentration values in the cultivars was as follows: Beijingxiaoza 56 > Suancaiwang > Quansheng and Qiubo 60 > Xianfengkuaicai and Chunkang. Similar order was also found in the bioaccumulation factor (BAF), translocation factor (TF), and metal extraction ratio (MER). Several soil Cd fractions after Beijingxiaoza 56 harvesting decreased most. Beijingxiaoza 56 is thus promising for phytoextraction of Cd from soils with low to moderate (<2.25 mg kg(-1)) Cd contamination.

[Effects of soil HHCB and Cd contamination on the growth of wheat seedlings (Triticum aestivum) and the pollutants accumulation in plants].

Using outdoor pot-culture experiment,biomasses of wheat seedlings and accumulation of HHCB and/or Cd in parts of wheat seedlings cultured in alluvial soil and cinnamon soil were investigated. The biomasses of wheat seedlings in different treatments followed the order as single HHCB treatment > HHCB and Cd treatment > single Cd treatment. The accumulation of HHCB in wheat seedlings cultured in alluvial soil was more than that in cinnamon soil, and effect of Cd on accumulation of HHCB in wheat seedlings cultured in alluvial soil was different to that in cinnamon soil. In alluvial soil, the accumulation of HHCB in different parts of wheat seedlings followed the sequence that root > stem > leaf. Cd significantly induced the accumulation of HHCB in wheat roots, but inhibited that of HHCB in wheat stems and leaves, and the highest inhibition rate was 44.07%. In cinnamon soil, the accumulation of HHCB in different parts of wheat seedlings followed the sequence that root > leaf > stem. The effect of Cd on accumulation of HHCB in wheat roots was not significant, but the median and high concentrations of Cd induced accumulation of HHCB in wheat stems and leaves significantly, and the highest induction rate was 35.95%. Besides, the accumulation of Cd in alluvial soil was lower than that in cinnamon soil, and HHCB could significantly induce the accumulation of Cd in wheat seedlings cultured in two different soils. The increasing rates of Cd accumulation in roots, stems and leaves in alluvial soil were 30.84%, 61.82% and 61.82%, and those in cinnamon soil were 41.53%, 184.16% and 206.18%, respectively. It is indicated that HHCB in cinnamon soil induced more accumulation of Cd in wheat seedlings than that in alluvial soil.

Remediation of petroleum contaminated soils by joint action of Pharbitis nil L. and its microbial community.

The plot-culture experiments were conducted for examining the feasibility of Pharbitis nil L. and its microbial community to remedy petroleum contaminated soils. The petroleum contaminated soil, containing 10% (w/w) of the total petroleum hydrocarbons (TPHs), was collected from the Shengli Oil Field, Dongying City, Shandong Province, China. The collected soil was applied and diluted to a series of petroleum contaminated soils (0.5%, 1.0%, 2.0% and 4.0%). Root length, microbial populations and numbers in the rhizosphere were also measured in this work. The results showed that there was significantly (p<0.05) greater degradation rate of TPHs in vegetated treatments, up to 27.63-67.42%, compared with the unvegetated controls (only 10.20-35.61%), after a 127-day incubation. Although various fractions of TPHs had an insignificant concentration difference due to the presence of the remediation plants, there was a much higher removal of saturated hydrocarbon compared with other components. The biomass of P. nil L. did not decrease significantly when the concentration of petroleum hydrocarbons in soil was ≤2.0%. The trends of microbial populations and numbers in the rhizosphere were similar to the biomass changes, with the exception that fungi at 0.5% petroleum contaminated soil had the largest microbial populations and numbers.

Phytoremediation of petroleum contaminated soils by Mirabilis Jalapa L. in a greenhouse plot experiment.

Phytoremediation of soils contaminated by organic chemicals is a challenging problem in environmental science and engineering. On the basis of identifying remediation plants from ornamentals, the remediation capability of Mirabilis Jalapa L. to treat petroleum contaminated soil from the Shengli Oil Field in Dongying City, Shandong Province, China was further investigated using a field plot experiment carried out in a greenhouse. The results showed that the average efficiency of removing total petroleum hydrocarbons (TPHs) by M. jalapa over the 127-day culture period was high, up to 41.61-63.20%, when the removal rate by natural attenuation was only 19.75-37.92%. The maximum reduction occurred in the saturated hydrocarbon fraction compared with other components of petroleum contaminants. According to the qualitative and quantitative parameters including plant height, fresh weight, dry weight, root length, root weight and visual stress symptoms, it was indicated that M. jalapa had a peculiar tolerance to petroleum contamination and could effectively promote the degradation of TPHs when the concentration of petroleum hydrocarbons in soil was equal to and lower than 10,000 mg/kg. The population of living microorganisms in the planted soil could be also adaptive to