Bioactive secondary metabolites from tomato-derived bacterium Bacillus velezensis Hnu24.

A series of secondary metabolites have been isolated from the genus of Bacillus velezensis, most of which show antibacterial and insecticidal activities. In order to find more bioactive secondary metabolites from B. velezensis, one new natural component aminoindole dimer baciindole A (1), together with seven known compounds (2-8) were isolated from the tomato-derived bacterium Bacillus velezensis Hnu24. The structure of compound 1 was elucidated by its HR-ESI-MS spectral data and 1 D/2D NMR spectroscopic analysis. Compound 3 showed antibacterial activity against Staphylococcus aureus, S. epidermidis and Ralstonia solanacearum with the MIC values of 3.125, 12.5 and 50 µg/mL, respectively. Compound 4 showed antibacterial activity against S. aureus with the MIC value of 12.5 µg/mL. Compound 3 showed cytotoxic activity for human colon cancer HTC116 cancer cells with the IC50 value of 8.42 ± 0.48 µM. Five compounds (1-4 and 8) were obtained from the strain of B. velezensis for the first time. These results indicated that 3 will be useful in developing antimicrobial and treatment of colon cancer agents.

Rational design of bimetallic MXene solid solution with High-Performance electrocatalytic N2 reduction.

Electrocatalytic N2 reduction reaction (eNRR) was an effective alternative method for green synthesis of NH3. By combining the first-principal Density functional theory (DFT) calculations and Monte Carlo (MC) simulation, we systematacially investigated 24 types equal-ratio bimetallic MXene solid solution, involving 88 different catalysts. Our focus was on the catalytic performance of these materials in eNRR. The computational result indicate that MoW(3Mo) has high stability, selectivity (93.8 % against the hydrogen evolution reaction (HER)) and activity (UL = -0.26 V), which is significantly better than that of monometal Mo2CO2 and W2CO2. This improvement in catalytic properties is attributed to the unique electronic structure (e.g. d-band center, charge) of bimetallic MXene solid solution. In explicit solvent conditions, the microenvironment of hydrogen bond in aqueous liquid thermodynamically promotes the catalytic property for eNRR and reduce the catalytic property of HER side reaction, but the kinetic barrier is also increased due to the effect of the hydrogen-bond microenvironment on proton migration. Overall, the obtained bimetallic MXene solid solution MoW(3Mo) exhibits excellent catalytic performance in eNRR.

Pulsed Laser Ablation in Water Synthesis of Black TiO2-Graphene Oxide Nanocomposites and the Enhanced Photocatalytic Performance.

Black TiO2-graphene oxide (GO) nanocomposites are synthesized via the pulsed laser ablating TiO2 powders and GO in deionized water. The simple process enables the preparation of black TiO2 nanoparticles and anchors them onto the GO sheet in one step. The TiO2-GO nanocomposites exhibit greatly enhancement for photocatalytic degradation of Rhodamine B (RB) dye in comparison with the pristine and the ablated black TiO2. The heterojunction structure plays an important role in efficient charge separation, which reduces the recombination of photogenerated electrons and holes. The unique two-dimensional structure of GO enables the composite to have a large specific surface area, and prevents the agglomeration of TiO2 nanoparticles, which are beneficial to the photocatalytic performance of the composite.

[Development of sensitive-micro RF coils in desktop MRI systems].

A RF coil (or probe) is one of the key components in NMR spectrometers and MRI systems, and designing a quality RF coil is a cheaper way to improves the signal-to-noise ratio (SNR) of systems and image quality. According to different applications there are a variety of RF coils. This article describes high-sensitive micro RF coils used in NMR spectrometers specially for test-tube samples. Their performance has been verified on the desktop MRI systems.