Applications of remote sensing using unmanned aerial vehicle (UAV) in agriculture has proved to be an effective and efficient way of obtaining field information. In this study, we validated the ...feasibility of utilizing multi-temporal color images acquired from a low altitude UAV-camera system to monitor real-time wheat growth status and to map within-field spatial variations of wheat yield for smallholder wheat growers, which could serve as references for site-specific operations. Firstly, eight orthomosaic images covering a small winter wheat field were generated to monitor wheat growth status from heading stage to ripening stage in Hokkaido, Japan. Multi-temporal orthomosaic images indicated straightforward sense of canopy color changes and spatial variations of tiller densities. Besides, the last two orthomosaic images taken from about two weeks prior to harvesting also notified the occurrence of lodging by visual inspection, which could be used to generate navigation maps guiding drivers or autonomous harvesting vehicles to adjust operation speed according to specific lodging situations for less harvesting loss. Subsequently orthomosaic images were geo-referenced so that further study on stepwise regression analysis among nine wheat yield samples and five color vegetation indices (CVI) could be conducted, which showed that wheat yield correlated with four accumulative CVIs of visible-band difference vegetation index (VDVI), normalized green-blue difference index (NGBDI), green-red ratio index (GRRI), and excess green vegetation index (ExG), with the coefficient of determination and RMSE as 0.94 and 0.02, respectively. The average value of sampled wheat yield was 8.6 t/ha. The regression model was also validated by using leave-one-out cross validation (LOOCV) method, of which root-mean-square error of predication (RMSEP) was 0.06. Finally, based on the stepwise regression model, a map of estimated wheat yield was generated, so that within-field spatial variations of wheat yield, which was usually seen as general information on soil fertility, water potential, tiller density, etc., could be better understood for applications of site-specific or variable-rate operations. Average yield of the studied field was also calculated according to the map of wheat yield as 7.2 t/ha.
Artificial photosynthetic solar‐to‐chemical cycles enable an entire environment to operate in a more complex, yet effective, way to perform natural photosynthesis. However, such artificial systems ...suffer from a lack of well‐established photocatalysts with the ability to harvest the solar spectrum and rich catalytic active‐site density. Benefiting from extensive experimental and theoretical investigations, this bottleneck may be overcome by devising a photocatalytic platform based on metal sulfides with predominant electronic, physical, and chemical properties. These tunable properties can endow them with abundant active sites, favorable light utilization, and expedited charge transportation for solar‐to‐chemical conversion. Here, it is described how some vital lessons extracted from previous investigations are employed to promote the further development of metal sulfides for artificial photosynthesis, including water splitting, CO2 reduction, N2 reduction, and pollutant removal. Their functions, properties, synthetic strategies, emerging issues, design principles, and intrinsic functional mechanisms for photocatalytic redox reactions are discussed in detail. Finally, the associated challenges and prospects for the utilization of metal sulfides are highlighted and future development trends in photocatalysis are envisioned.
The emerging unique properties of metal sulfide photocatalysts, including abundant active sites, light‐harvesting ability, and expedited charge separation, endow them promising candidates for solar light conversion. This review aims to offer a full‐scale lens to discuss the recent advances of metal sulfides photocatalysts, propose their challenges, and envision the prospects of the development of metal sulfides for photocatalytic redox reactions.
Hollow structures with an efficient light harvesting and tunable interior component offer great advantages for constructing a Z‐scheme system. Controlled design of hollow cobalt sulfide (Co9S8) cubes ...embedded with cadmium sulfide quantum dots (QDs) is described, using hollow Co(OH)2 as the template and a one‐pot hydrothermal strategy. The hollow CdS/Co9S8 cubes utilize multiple reflections of light in the cubic structure to achieve enhanced photocatalytic activity. Importantly, the photoexcited charge carriers can be effectively separated by the construction of a redox‐mediator‐free Z‐scheme system. The hydrogen evolution rate over hollow CdS/Co9S8 is 134 and 9.1 times higher than that of pure hollow Co9S8 and CdS QDs under simulated solar light irradiation, respectively. Moreover, this is the first report describing construction of a hollow Co9S8 based Z‐scheme system for photocatalytic water splitting, which gives full play to the advantages of light‐harvesting and charges separation.
Fair and square: An efficient light‐ harvesting CdS/Co9S8 catalyst was prepared for direct Z‐scheme photocatalytic water splitting. Hollow Co9S8 cubes eliminate photocorrosion phenomena typical of pure CdS quantum dots and improve harvesting of solar light, thus greatly enhancing photocatalytic H2 evolution.
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•Both indirect oxidation and direct urea electro-oxidation paths exist on nickel.•Rate determining step depends on polarization potential and KOH concentration.•Nickel catalyst is ...poisoned by the CO2 intermediate.
Urea electro-oxidation reaction in alkaline medium is systematically analyzed by electrochemical impedance spectroscopy (EIS). The effects of polarization potential and KOH concentration on the impedance appearance are investigated. In the presence of urea, it is found that Nyquist plots exhibit two depressed semicircles, with one at higher frequencies stably locating in the first quadrant while the other’s location at lower frequencies varying between the first and second quadrant as the polarization potential changes. Results show both indirect and direct pathways proceed in urea electro-oxidation reaction. A mathematical model indicates the reverse loop in the Nyquist plots is attributed to CO2 poisoning on the catalyst, which is also validated by the followed chronoamperometric method. Moreover, the rate determining steps of urea electro-oxidation reaction is dependent on KOH concentration. The EIS technique gives a new sight to interpret the poor stability of urea electro-oxidation on nickel catalyst, and thus helps to explore a CO2-insensitive catalyst.
Precise manipulation of optical properties through the structure‐evolution of plasmonic nanoparticles is of great interest in biomedical fields including bioimaging and phototherapy. However, ...previous success has been limited to fixed assembled structures or visible–NIR‐I absorption. Here, an activatable NIR‐II plasmonic theranostics system based on silica‐encapsulated self‐assembled gold nanochains (AuNCs@SiO2) for accurate tumor diagnosis and effective treatment is reported. This transformable chain structure breaks through the traditional molecular imaging window, whose absorption can be redshifted from the visible to the NIR‐II region owing to the fusion between adjacent gold nanoparticles in the restricted local space of AuNCs@SiO2 triggered by the high H2O2 level in the tumor microenvironment (TME), leading to the generation of a new string‐like structure with strong NIR‐II absorption, which is further confirmed by finite‐difference‐time‐domain (FDTD) simulation. With the TME‐activated characteristics, AuNCs@SiO2 exhibits excellent properties for photoacoustic imaging and a high photothermal conversion efficiency of 82.2% at 1064 nm leading to severe cell death and remarkable tumor growth inhibition in vivo. These prominent intelligent TME‐responsive features of AuNCs@SiO2 may open up a new avenue to explore optical regulated nano‐platform for intelligent, accurate, and noninvasive theranostics in NIR‐II window.
An activatable NIR‐II plasmonic theranostics system for accurate tumor diagnosis and effective treatment is reported. This gold nanochain structure breaks through the traditional molecular imaging window, shifting from the visible to the NIR‐II region, owing to fusion between adjacent gold nanoparticles in the restricted local space triggered by the high H2O2 level in the tumor microenvironment.
Abstract
We recently showed that forkhead-box class O1 (FoxO1) activation protects against high glucose–induced injury by preventing mitochondrial dysfunction in the rat kidney cortex. In addition, ...FoxO1 has been reported to mediate putative kinase 1 (PINK1) transcription and promote autophagy in response to mitochondrial oxidative stress in murine cardiomyocytes. In this study, we ascertained whether overexpressing FoxO1 in the kidney cortex reverses preestablished diabetic nephropathy in animal models. The effect of FoxO1 on mitophagy signaling pathways was evaluated in mouse podocytes. In vivo experiments were performed in male KM mice. A mouse model of streptozotocin (STZ)-induced type 1 diabetes (T1D) was used, and lentiviral vectors were injected into the kidney cortex to overexpress FoxO1. A mouse podocyte cell line was treated with high concentrations of glucose and genetically modified using lentiviral vectors. We found aberrant mitochondrial morphology and reduced adenosine triphosphate production. These mitochondrial abnormalities were due to decreased mitophagy via reduced phosphatase/tensin homolog on chromosome 10–induced PINK1/Parkin-dependent signaling. FoxO1 upregulation and PINK1/Parkin pathway activation can individually restore injured podocytes in STZ-induced T1D mice. Our results link the antioxidative activity of FoxO1 with PINK1/Parkin-induced mitophagy, indicating a novel role of FoxO1 in diabetic nephropathy.
FoxO1 is sufficient to promote mitochondrial dysfunction and podocyte injury under high-glucose conditions with an increased level of PINK1.
The Photo-Fenton reaction is an advanced technology to eliminate organic pollutants in environmental chemistry. Moreover, the conversion rate of Fe(3+)/Fe(2+) and utilization rate of H2O2 are ...significant factors in Photo-Fenton reaction. In this work, we reported three dimensional (3D) hierarchical cobalt ferrite/graphene aerogels (CoFe2O4/GAs) composites by the in situ growing CoFe2O4 crystal seeds on the graphene oxide (GO) followed by the hydrothermal process. The resulting CoFe2O4/GAs composites demonstrated 3D hierarchical pore structure with mesopores (14~18 nm), macropores (50~125 nm), and a remarkable surface area (177.8 m(2 )g(-1)). These properties endowed this hybrid with the high and recyclable Photo-Fenton activity for methyl orange pollutant degradation. More importantly, the CoFe2O4/GAs composites can keep high Photo-Fenton activity in a wide pH. Besides, the CoFe2O4/GAs composites also exhibited excellent cyclic performance and good rate capability. The 3D framework can not only effectively prevent the volume expansion and aggregation of CoFe2O4 nanoparticles during the charge/discharge processes for Lithium-ion batteries (LIBs), but also shorten lithium ions and electron diffusion length in 3D pathways. These results indicated a broaden application prospect of 3D-graphene based hybrids in wastewater treatment and energy storage.
In this study, commercial molybdenum sulfide with stability can directly activating peroxymonosulfate (PMS). Based on the experiment and density functional theory (DFT) calculation, the exposed Mo4+ ...can be combined with PMS molecules and effectively activate PMS decomposition to generate active radicals for organic pollutants oxidation.
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Although MoS2 has been proved to be a very ideal cocatalyst in advanced oxidation process (AOPs), the activation process of peroxymonosulfate (PMS) is still inseparable from metal ions which inevitably brings the risk of secondary pollution and it is not conducive to large-scale industrial application. In this study, the commercial MoS2, as a durable and efficient catalyst, was used for directly activating PMS to degrade aromatic organic pollutant. The commercial MoS2/PMS catalytic system demonstrated excellent removal efficiency of phenol and the total organic carbon (TOC) residual rate reach to 25%. The degradation rate was significantly reduced if the used MoS2 was directly carried out the next cycle experiment without any post-treatment. Interestingly, the commercial MoS2 after post-treated with H2O2 can exhibit good stability and recyclability for cyclic degradation of phenol. Furthermore, the mechanism for the activation of PMS had been investigated by density functional theory (DFT) calculation. The renewable Mo4+ exposed on the surface of MoS2 was deduced as the primary active site, which realized the direct activation of PMS and avoided secondary pollution. Taking into account the reaction cost and efficient activity, the development of commercial MoS2 catalytic system is expected to be applied in industrial wastewater.
In this paper, the coupling effect of dimple depth and fluid properties on convective heat transfer of kerosene flowing in a small-scale rectangular duct with circular dimples is studied numerically. ...The numerical simulation is based on Reynolds average method with a shear stress transport (SST)
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turbulence model and a 10-components surrogate model of kerosene. Turbulent flow and heat transfer properties in different depths of circular dimples are obtained. The results show that the three-dimensional vortices are generated by dimples and the vortices alter local turbulent flowing significantly, leading to both enhanced and reduced convective heat transfer to the wall at different locations. It is also found that the averaged Nusselt number on different dimpled walls first increases in the raising of dimple depths and then decreases after dimple depths reach a certain value. The obtained flow field shows that the heat transfer enhancement on the dimpled wall is caused by vortices with horse-shoe and tornado structures. When dimple depth further increases, the vortical structure changes to asymmetric horn spiral form, which causes heat transfer reduction. Similar to the variation of Nusselt number, the friction factor through dimpled duct also increases firstly with the dimple depth and then decreases.
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