Upcycle polyethylene terephthalate waste by photoreforming: Bifunction of Pt cocatalyst.

Upcycle polyethylene terephthalate (PET) waste by photoreforming (PR) is a sustainable and green approach to tackle environmental problems but with challenges to obtain valuable oxidation products and high purity hydrogen simultaneously. Noble metal cocatalysts are essential to enhance the overall PR reaction efficacy. In this work, TiO2 nanotubes (TiO2 NTs) decorated with single Pt atoms (Pt1/TiO2) or Pt nanoparticles (PtNPs/TiO2) are used in the photoreforming reaction (in one batch), and the oxidation products from ethylene glycol (EG, hydrolysed product of PET) in liquid phase and hydrogen are detected. With Pt1/TiO2, EG is oxidized to glyoxal, glyoxylate or lactate, and hydrogen evolution rate (r H2) reaches 51.8 µmol⋅h-1⋅gcat-1, that is 30 times higher than that of TiO2. For PtNPs/TiO2 (size of Pt NPs: 1.97 nm), hydrogen evolution reaches 219.1 µmol⋅h-1⋅gcat-1, but with the oxidation product of acetate only. DFT calculation demonstrates that for Pt NPs, the reaction path for hydrogen evolution is preferred thermodynamically, due to the formation of Schottky junction. On the oxidation of EG, theoretical and spectroscopic analysis suggest that bidentate adsorption of EG at the interface is facile on Pt1/TiO2, compared to that on PtNPs/TiO2 (two Pt sites), but oxidation products, adsorb less strongly, compared to PtNPs/TiO2, that eventually regulates the distribution of oxidation products. The results thus demonstrate the bifunctions of Pt in the PR reaction, i.e., electron transfer mediator for hydrogen evolution and reactive sites for molecules adsorption. The oxidation reaction is dominated by the adsorption-desorption behavior of molecules but the reduction reaction is controlled by the electron transfer. In addition, acidification of pretreated PET alkaline solution achieves separation of pure terephthalic acid (PTA), which further improves the reaction efficiency possibly by offering high density of active sites and acidic environment. Our work thus demonstrates that to upcycle PET plastics, an optimized process can be reached by atomic design of photocatalysts and proper treatment on the plastic wastes.

Noble-Metal-Free Single- and Dual-Atom Catalysts for Artificial Photosynthesis.

Artificial photosynthesis enables direct solar-to-chemical energy conversion aimed at mitigating environmental pollution and producing solar fuels and chemicals in a green and sustainable approach, and efficient, robust, and low-cost photocatalysts are the heart of artificial photosynthesis systems. As an emerging new class of cocatalytic materials, single-atom catalysts (SACs) and dual-atom catalysts (DACs) have received a great deal of current attention due to their maximal atom utilization and unique photocatalytic properties, whereas noble-metal-free ones impart abundance, availability, and cost-effectiveness allowing for scalable implementation. This review outlines the fundamental principles and synthetic methods of SACs and DACs and summarizes the most recent advances in SACs (Co, Fe, Cu, Ni, Bi, Al, Sn, Er, La, Ba, etc.) and DACs (CuNi, FeCo, InCu, KNa, CoCo, CuCu, etc.) based on non-noble metals, confined on an arsenal of organic or inorganic substrates (polymeric carbon nitride, metal oxides, metal sulfides, metal-organic frameworks, carbon, etc.) acting as versatile scaffolds in solar-light-driven photocatalytic reactions, including hydrogen evolution, carbon dioxide reduction, methane conversion, organic synthesis, nitrogen fixation, hydrogen peroxide production, and environmental remediation. The review concludes with the challenges, opportunities, and future prospects of noble-metal-free SACs and DACs for artificial photosynthesis.

Aerofoil optimization for improving the power performance of a vertical axis wind turbine using multiple streamtube model and genetic algorithm.

This paper reports on the optimization of the NACA0015 aerofoil for improving the power performance of a vertical axis wind turbine (VAWT). The target range of the chord Re is 3 × 105-106, the tip speed ratio (TSR) is 2-6 and the solidity is 0.2-0.6. This aerofoil is widely applied in small-scale VAWTs. In the optimization process, in which the class and shape function transformation parametrization method was used to perturb the aerofoil geometry, the thickness and camber of the aerofoil were selected as the constraints and the value of the maximum tangential force coefficient was chosen as the objective function. The aerodynamic performance of the aerofoil was calculated by combining the XFOIL program and Viterna-Corrigan post-stall model, while the aerofoil's performance was validated with computational fluid dynamic simulations. The results illustrated that, compared to an unoptimized NACA0015 aerofoil, the optimized aerofoil's lift to drag ratio was improved over a wide range of attack angles and the stall performance was gentler. The maximum lift coefficient, the maximum lift to drag ratio and the maximum tangential force coefficient were increased by 7.5%, 9% and 8.87%, respectively. Finally, this paper predicted the rotor efficiency with both the unoptimized and optimized NACA0015 aerofoils for different TSRs and different solidities using the multiple streamtube model. The results showed that the rotor with the optimized aerofoil has a higher efficiency.

POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator.

PURPOSE: This study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD). METHODS: 2D particle image velocimetry measurements were conducted on region (x/h = 0-2.25) and reattachment zone in the x-y plane over the backward-facing step at a Reynolds number of Re h  = 27,766 (based on step height [Formula: see text] and free stream velocity [Formula: see text]. The separated shear layer was excited by specially designed right-angle-shaped plasma actuator under the normalized excitation frequency St h  ≈ 0.345 along the 45° direction. The spatial distribution of each Reynolds stress component was reconstructed using an increasing number of POD modes. RESULTS: The POD analysis indicated that the flow dynamic downstream of the step was dominated by large-scale flow structures, which contributed to streamwise Reynolds stress and Reynolds shear stress. The intense Reynolds stress localized to a narrow strip within the shear layer was mainly affected by small-scale flow structures, which were responsible for the recovery of the Reynolds stress peak. With plasma excitation, a significant increase was obtained in the vertical Reynolds stress peak. CONCLUSIONS: Under the dimensionless frequencies St h  ≈ 0.345 and [Formula: see text] which are based on the step height and momentum thickness, the effectiveness of the flow control forced by the plasma actuator along the 45° direction was ordinary. Only the vertical Reynolds stress was significantly affected.

Antioxidant enzyme influences germination, stress tolerance, and virulence of Isaria fumosorosea.

Antioxidizing enzymes (superoxide dismutase, catalase, and glutathione peroxidae) are important enzymatic systems used to degrade hydrogen peroxide into water and oxygen, thereby lowering intracellular hydrogen peroxide levels. Entomopathogenic fungi display increased activities of antioxidizing enzymes during growth and germination, which is necessary to counteract the hyperoxidant state produced by oxidative metabolism. We studied the influence of different carbon sources on antioxidizing enzyme production by Isaria fumosorosea to determine the importance of antioxiding enzymes induction in fungal germination, stress tolerance and virulence. Conidia produced by colonies grown on hydrocarbons showed higher rates of enzyme activities compared to the control and the enzyme activities of the conidia produced on n-octacosane were higher than all the other treatments. The lipid peroxidation activities were observed as an indicative marker of oxidative damage to cells and the lowest levels of lipid peroxidation activities were observed for n-octacosane treatment. The increased enzyme activities of n-octacosane- grown conidia were accompanied by higher levels of resistance to exogenous hydrogen peroxide, reduction in germination time and higher virulence against Spodoptera exigua. Our study has helped to identify that increased activities of antioxidizing enzymes can improve the germination and tolerance to antioxidant stress response of I. fumosorosea.

Bufalin enhances the anti-proliferative effect of sorafenib on human hepatocellular carcinoma cells through downregulation of ERK.

The purpose of this study was to investigate the effect of bufalin on the anti-proliferative activity of sorafenib in the human hepatocellular carcinoma (HCC) cell lines PLC/PRF/5 and Hep G-2 and to determine the relevant molecular mechanism. Concurrent treatment with sorafenib and bufalin at a fixed ratio (25:1) for 48 h resulted in synergistic growth inhibition in HCC cell lines as determined by CCK-8 cell viability assays. Exposure of both PLC/PRF/5 and Hep G-2 cells to this combination of sorafenib (6.25 µM) and bufalin (50 nM) resulted in noticeable increases in apoptotic cell death, as evidenced by the disruption of mitochondria, compared to treatment with either agent alone. Although both sorafenib (6.25 µM) and bufalin (250 nM) alone inhibited the phosphorylation of ERK, the reduction in pERK was more pronounced in the cells treated with a combination of bufalin (50 nM) and sorafenib (250 nM). Furthermore, the inhibitory effect of bufalin on pERK was blocked by the PI3kinase inhibitor LY294002, suggesting that the reduction in pERK induced by bufalin might be mediated by AKT in these two HCC cell lines. Taken together, the results of our study suggest that bufalin enhances the anti-cancer effects of sorafenib on PLC/PRF/5 and Hep G-2 by contributing to the downregulation of ERK.

Na+/K+-ATPase α3 mediates sensitivity of hepatocellular carcinoma cells to bufalin.

Bufalin, a major bioactive component of the Chinese medicine Chansu, has been reported to exhibit significant antitumor activity against various cancer cell lines. However, the exact mechanism remains unclear. In this study, we demonstrated that bufalin inhibited the growth of hepatocellular carcinoma (HCC) cells in a dose-dependent manner, which correlated with the expression level of Na+/K+-ATPase α3 in HCC cells. The IC50 of bufalin markedly increased when Na+/K+-ATPase α3 was silenced by RNA interference. Furthermore, we show that bufalin increased the phosphorylation of Akt and ERK1/2 while inhibited FoxO3a expression. Thus, our study suggests that Na+/K+-ATPase α3 might serve as a therapeutic target for bufalin in HCC, and its expression status may help predict sensitivity of HCC cells to bufalin treatment.

Rhizobium oryzae sp. nov., isolated from the wild rice Oryza alta.

During a study of endophytic nitrogen-fixing bacteria present in the wild rice species Oryza alta, eight novel isolates were obtained from surface-sterilized roots and classified in the genus Rhizobium on the basis of almost-complete 16S rRNA gene sequence analysis. These strains can nodulate Phaseolus vulgaris and Glycine max. The highly similar protein patterns, DNA fingerprint patterns of insertion sequence-based PCR (IS-PCR) and DNA-DNA hybridizations showed that these novel isolates were members of the same species. The closest phylogenetic relatives of the representative strain Alt 505(T) of the novel group were Rhizobium etli CFN 42(T) and Rhizobium indigoferae CCBAU 71714(T), with 96.2 and 96.0% 16S rRNA gene sequence similarity, respectively. Low DNA-DNA relatedness with the type strains of R. etli, R. indigoferae, Rhizobium hainanense, Rhizobium mongolense and Rhizobium galegae and differences in IS-PCR fingerprinting patterns, SDS-PAGE of proteins, antibiotic resistance, phenotypic tests and comparison of cellular fatty acids with Rhizobium species indicated that the novel group of isolates were distinct from previously described species. Based on these results, we propose to place them in a novel species, as Rhizobium oryzae sp. nov. The type strain is Alt 505(T) (=LMG 24253(T) =CGMCC 1.7048(T)).

[Relationships between soil microbial ecological characteristics and physical-chemical properties of vegetable garden soil].

The study on the 64 vegetable garden soil samples in the Baiyuan District of Guangzhou City showed that there were significantly positive correlations of soil microbial biomass carbon (Cmic) with soil total N, alkali-hydrolygable N, available K, cation exchange capacity (CEC) and organic matter (OM), of soil microbial biomass nitrogen (Nmic) with soil total N, total P, CEC and OM, of soil basal respiration (SBR) with soil total N, alkali-hydrolygable N, available K, CEC and OM, of AWCD with soil total N and OM, and of Shannon diversity index with soil total N and CEC. Low alkali-hydrolygable N increased Cmic SBR, and metabolic quotient (qCO2), while high alkali-hydrolygable N decreased qCO2. High available P decreased Cmic, Nmic and microbial quotient, and a high ratio of available P to alkali-hydrolygable N was related to the decrease of Cmic, Nmic, Cmic/Nmic and SBR. It was suggested that there were significant correlations between soil microbial ecological characteristics and physico-chemical properties, and excessive available nutrients or inappropriate ratios of alkali-hydrolygable N to available P in soil were harmful to soil microbes.