Search

Throughfall makes up the major portion of understory rainfall, and thereby plays a vital role in regulating the hydrological and biogeochemical processes in forest ecosystems. The aim of this study was to explore the alterations in throughfall and the associated chemical composition (Ca2+, Na2+, K+, Mg2+, H+, SO42−, NO3−, Cl−, and F−) under Quercus acutissima Carruth. and Broussonetia papyrifera (L.) L’Her. ex Vent. trees, in relation to trunk distance and rainfall characteristics. Event-based measurements were carried out from April to December 2018 in a subtropical forest of eastern China. The throughfall amount (TF) and throughfall ratio (TF%) of Q. acutissima (35.7 mm, 83.0%) were higher than those of B. papyrifera (32.1 mm, 74.7%). Although no significant species differences in the ion concentrations of throughfall were detected, almost all ions (Ca2+, Na2+, K+, Mg2+, H+, SO42−, NO3−, and Cl−) were enriched after passing through the canopies of the two tree species. TF and TF% increased with increasing distance from the trunk, while the concentrations of most ions in throughfall increased, since the trunk was approximated. Regression analysis and redundancy analysis revealed that rainfall amount, duration and intensity exerted significant impacts on throughfall generation and ion concentrations, and the antecedent dry period had a notable influence only on ion concentrations. Our findings indicated that forest canopy and rainfall characteristics play an important role in the alterations in throughfall and the associated chemical compositions.

Manganese dioxide (MnO2) is a promising electrode material for supercapacitors due to its high capacitance, environment friendly, and low cost. However, it shows low specific capacitance and poor circulation in practice because of the disintegration of MnO2 in charge–discharge process. In this review, the synthesis and electrochemical properties of MnO2 and MnO2-based composites with various structures have been discussed in detail. In addition, the development prospect of MnO2-based composites has been discussed.

Surfactants are always added to coating formulations to ensure good adhesion of edible coatings to a product’s surface and to maintain freshness. In this study, the effects of the mix surfactants Tween 20 and Span 80 with different hydrophile–lipophile balance (HLB) values on the film-forming ability, wettability, and preservation capacity of blueberry sodium alginate coating were investigated. The results indicated that Tween 20 obviously ensured favorable wettability and improved the uniformity and mechanical properties of the resulting film. While the addition of Span 80 reduced the mean particle size of the coating, enhanced the water resistance of the film, and helped to reduce blueberry weight loss. A sodium alginate coating with low viscosity and medium HLB could better inhibit the galactose, sucrose, and linoleic acid metabolism of blueberries, reduce the consumption of phenols, promote the accumulation of flavonoids, and thus display superior coating performance. In summary, sodium alginate coating with medium HLB had comprehensive advantages in film-forming ability and wettability and was conducive to the fresh-keeping role.

Traditional metal–organic frameworks (MOFs), although have the ability to accumulate some chemicals from solution, are usually electrochemically inert. Here, spherical MIL-53(NiFe) MOFs have been synthesized via a simple solvothermal method. A series of characterization methods including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometry, energy dispersive X-ray spectroscopy (EDS), and element mapping were used to investigate this material. An MIL-53(NiFe)/AB/GCE-modified electrode was constructed using acetylene black (AB) as the conductive substrate, which can make up for the electrochemical inertness of metal in the MOFs to some extent. Moreover, the bimetallic center can coordinate with the azo functional group in Sudan I to some extent, which is beneficial to the binding of the molecules to the electrode. Thus, the sensitive and rapid detection of Sudan I can be realized. The quantitative determination of Sudan I was carried out via the differential pulse voltammetry (DPV) method in a wider linear range (0.005–10 μM) and lower detection limit (0.002 μM, S/N = 3). The developed method can be successfully applied to the detection of Sudan I in chilli powder and tomato paste with satisfactory results.

Surface defect detection for printed circuit board (PCB) is indispensable for managing PCB production quality. However, automatic detection of PCB surface defects is still a challenging task because, even within the same category of surface defect, defects present great differences in morphology and pattern. Although many computer vision-based detectors have been established to handle these problems, current detectors struggle to achieve high detection accuracy, fast detection speed and low memory consumption simultaneously. To address those issues, we propose a cost-effective deep learning (DL)-based detector based on the cutting-edge YOLOv4 to detect PCB surface defect quickly and efficiently. The YOLOv4 is improved upon with respect to its backbone network and the activation function in its neck/prediction network. The improved YOLOv4 is evaluated with a customized dataset, collected from a PCB factory. The experimental results show that the improved detector achieved a high performance, scoring 98.64% on mean average precision (mAP) at 56.98 frames per second (FPS), outperforming the other compared SOTA detectors. Furthermore, the improved YOLOv4 reduced the parameter space of YOLOv4 from 63.96 M to 39.59 M and the number of multiply-accumulate operations (Madds) from 59.75 G to 26.15 G.

In this study, chitosan (CH) coating with different number-average molecular weight (MW, ca. 5, 19 and 61 kDa) was electrostatic sprayed on strawberry. The effects of MW on strawberry quality changes were evaluated during 15 days of storage at 4 °C. The qualities of strawberry included mold growth, weight loss, firmness, total soluble solids (TSS), pH, flavonoids content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. Results showed that CH coating could significantly maintain the strawberry qualities during storage compared to uncoated treatment. CH coating with 61 kDa was more effective in retarding the increases of pH and MDA, and could better maintain flavonoids content. However, MW had no significant impact on mold growth, weight loss, firmness, SOD activity of coated strawberry. According to evaluation criteria, CH coating with 61 kDa had better performance on strawberry preservation with the highest synthetic value (6.93), and could be used to maintain quality and prolong the shelf life of strawberry during cold storage.

This study used electrostatic spraying (ES) system as an efficient technique for strawberry preservation with chitosan (CH) coating. The effects of CH deacetylation degree (DD, 81.0, 88.1 and 95.2%) on the qualities (weight loss, pH, total soluble solids (TSS), firmness, flavonoids content, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity and mold growth) of strawberry during cold storage were investigated. Results showed that CH coating by ES formed more continuous and uniform protective layer compared with conventional spraying (CS). CH coating effectively enhanced the overall quality and extended shelf life of strawberry at least 2 days. CH coating with 81.0% and 88.1% DD were more effective in reducing weight loss of strawberry, and CH coating with 88.1% DD could better maintain TSS content, while CH coating with 95.2% DD delayed the decline in flavonoids more obviously. However, DD had no significant impact on pH, firmness, SOD activity, MDA and mold growth of coated samples. The evaluation criteria indicated CH coating with 88.1% DD had better preservation performance with the highest synthetic value (6.17) during storage. These findings suggest that CH coating especially with 88.1% DD by ES, as a safe, cheap and efficient technique, has great potential for industrial application of fruit preservation.

Global warming and drying have caused desiccation of lakes in arid and semi-arid regions worldwide, and the mechanisms underlying sharp decreases in water level of great lakes in arid and semi-arid regions in recent decades require elucidation. Using a combination of multiple statistical and modeling methods, we extracted multi-decadal trends from water level time series (~1960–2017) of the two largest lakes in northern China, and explored the influences of hydro-meteorological factors on the multi-decadal and inter-annual variation in lake water level. The hydrology components of the Hulun Lake basin varied with greater amplitude than those of the Qinghai Lake basin, with water level decreases of 5.3 (1991–2011) and 3.1 (1961–2004) m in Hulun Lake and Qinghai Lake, respectively. River runoff influenced multi-decadal changes in water level of the two great lakes most, followed by lake surface evaporation and precipitation at the lake surface. Lake surface evaporation, driven by potential evaporation and lake area dynamics, was the largest hydrology component of the two great lakes. Lake surface evaporation mitigated the decline of Hulun Lake over 1995–2011, while it aggravated the decline of Qinghai Lake over 1990–2005. Although El Nino–Southern Oscillation significantly affected various hydro-meteorological factors, it contributed less than 6% of inter-annual variation in Hulun Lake, and no significant effect on the variation in Qinghai Lake was found. Pan evaporation was negatively correlated with precipitation and land evapotranspiration in both great lake basins.

In this article, a new synthetic method of nanoparticles with fresh Chinese gooseberry juice (CGJ) as bio-template was developed. One-step synthesis of highly water-soluble silver nanoparticles at room temperature without using any harmful reducing agents and special capping agent was fulfilled with this method. In the process, the products were obtained by adding AgNO3 to CGJ, which was used as reducing agent, capping agent, and the bio-template. The products of silver nanoparticles with diameter of 10–30 nm have strong water solubility and excellent antibiotic function. With the same concentration 0.047 μg mL−1, the antibacterial effect of water-soluble silver particles by fresh CGJ was 53%, whereas only 27% for silver nanoparticles synthesized using the template method of fresh onion inner squama coat (OISC). The excellent water solubility of the products would enable them have better applications in the bio-medical field. The synthetic method would also have potential application in preparing other highly water-soluble particles, because of its simple apparatus, high yield, mild conditions, and facile operation.