Review of Calibration Methods for Scheimpflug Camera

The Scheimpflug camera offers a wide range of applications in the field of typical close-range photogrammetry, particle image velocity, and digital image correlation due to the fact that the depth-of-view of Scheimpflug camera can be greatly extended according to the Scheimpflug condition. Yet, the conventional calibration methods are not applicable in this case because the assumptions used by classical calibration methodologies are not valid anymore for cameras undergoing Scheimpflug condition. Therefore, various methods have been investigated to solve the problem over the last few years. However, no comprehensive review exists that provides an insight into recent calibration methods of Scheimpflug cameras. This paper presents a survey of recent calibration methods of Scheimpflug cameras with perspective lens, including the general nonparametric imaging model, and analyzes in detail the advantages and drawbacks of the mainstream calibration models with respect to each other. Real data experiments including calibrations, reconstructions, and measurements are performed to assess the performance of the models. The results reveal that the accuracies of the RMM, PLVM, PCIM, and GNIM are basically equal, while the accuracy of GNIM is slightly lower compared with the other three parametric models. Moreover, the experimental results reveal that the parameters of the tangential distortion are likely coupled with the tilt angle of the sensor in Scheimpflug calibration models. The work of this paper lays the foundation of further research of Scheimpflug cameras

Microbial reduction and migration of As/Fe mediated by electron shuttle: Differences between incorporated and adsorbed As(V)

Metal-reducing bacteria play a central and important role in the biogeochemical cycle of arsenic (As) and iron (Fe). Research on As/Fe migration from arsenic-containing iron minerals mediated by electronic shuttles is of significance to groundwater protection and human health. Further, the redox activity and bioavailability of goethite with differing occurrence and distribution of arsenic have not been studied clearly. In this study, the function of electron shuttle AQDS in Fe(III) bioreduction was determined. It was found that acidic conditions were conducive to the growth and reproduction of strain D2201, which was beneficial to the reduction of As(V)/Fe(III). The OD600nm value of the bacteria at pH 6 exceeded twice that at pH 8. Then, three types of goethite, namely pure goethite (Gt), coprecipitated As(V)-goethite (Gt-As), and adsorbed arsenic-goethite (Gt∗As), were compared for microbial reduction reactivity. X-ray photoelectron spectroscopy analysis illustrated the proportion of OH- content in Gt-As was much lower than that of Gt and Gt∗As, indicating Gt-As carried more surface defects and had higher bioavailability. The Fe(II) content released from AQDS-mediated bioreduction of Gt-As was two-fold higher than that of Gt and Gt∗As at pH 7. In addition, pH significantly affected goethite bioreduction efficiency and arsenic migration degree. The dissolved Fe(II) concentration for Gt-As was 0.98, 0.133, and 0.139 ​mM at pH 6, 7, and 8, respectively; corresponding to dissolved As(T) content of 3.51, 1.48, and 1.31 ​μM within 9 days of culture. This study highlights the significant influence of AQDS and mineral structure on the As/Fe biochemical cycle, which will help further develop the bioremediation of arsenic-contaminated sediments

Influence of Sulfate Reduction on Arsenic Migration and Transformation in Groundwater Environment

The sulfate-reducing bacteria-mediated reduction process is considered to be an important mechanism affecting arsenic migration and transformation in anaerobic environments. To investigate the effect of sulfate-reducing bacteria in a high-arsenic aquifer on arsenic migration and transformation, the typical sulfate-reducing bacteria Desulfovibrio vulgaris was selected for micro-cosmic experiments to simulate a groundwater environment with or without sulfate amendment. The reduction of Fe(III) and As(V) by Desulfovibrio vulgaris was identified, and Fe(III) and As(V) were reduced in both sulfate-free and sulfate-containing systems. However, the addition of 1 mM sulfate significantly enhanced Fe(III) and As(V) reduction. Compared with no sulfate addition, 1 mM sulfate increased the reduction rates of Fe(III) and As(V) by 111.9% and 402.2%, respectively. The sulfate process mediated by Desulfovibrio vulgaris also remarkably promoted arsenic release in sediments. These results indicated that sulfate concentration should be considered when sulfate reduction is used as a remediation method for arsenic pollution in groundwater

A reanalysis of the relationship between the size of boulders and craters in lunar surface

To distinguish secondary craters from primary craters is very important in lunar studies that involve such tasks as dating the lunar surface and investigating the meteoritic flux. However, this is usually difficult since distant secondary craters generally have an appearance similar to primary ones. Bart and Melosh (2007a, 2007b) proposed a method to distinguish the two types of craters based on the relationship between the crater diameter (D) and the size of the largest boulder (B) around the crater: B =KD2/3, where K is the fitting coefficient. They concluded that secondary craters have a 60% larger fitting coefficient (K) than primary craters. However, because of the poor quality of the available data and an insufficient number of crater samples, their results need further substantiation, as they have suggested. This research aims to examine their results with recently obtained very high resolution data and many more sampled craters. Our results indicate that the criterion proposed by Bart and Melosh (2007a, 2007b) is actually not applicable, i.e., the fitted coefficient (K), in cases of primary and secondary craters, cannot be confidently distinguished

Influence of Sulfate Reduction on Arsenic Migration and Transformation in Groundwater Environment

The sulfate-reducing bacteria-mediated reduction process is considered to be an important mechanism affecting arsenic migration and transformation in anaerobic environments. To investigate the effect of sulfate-reducing bacteria in a high-arsenic aquifer on arsenic migration and transformation, the typical sulfate-reducing bacteria Desulfovibrio vulgaris was selected for micro-cosmic experiments to simulate a groundwater environment with or without sulfate amendment. The reduction of Fe(III) and As(V) by Desulfovibrio vulgaris was identified, and Fe(III) and As(V) were reduced in both sulfate-free and sulfate-containing systems. However, the addition of 1 mM sulfate significantly enhanced Fe(III) and As(V) reduction. Compared with no sulfate addition, 1 mM sulfate increased the reduction rates of Fe(III) and As(V) by 111.9% and 402.2%, respectively. The sulfate process mediated by Desulfovibrio vulgaris also remarkably promoted arsenic release in sediments. These results indicated that sulfate concentration should be considered when sulfate reduction is used as a remediation method for arsenic pollution in groundwater

Inhibitory Effect of Guava Leaf Polyphenols on Advanced Glycation End Products of Frozen Chicken Meatballs (−18 °C) and Its Mechanism Analysis

The inhibitory effect of guava leaf polyphenols (GLP) on advanced glycation end products (AGEs) of frozen chicken meatballs (−18 °C) and its possible inhibitory mechanism was investigated. Compared with control samples after freezing for 6 months, acidic value (AV), lipid peroxides, thiobarbituric acid reactive substance (TBARS), A294, A420, glyoxal (GO), Nε-carboxymethyl-lysine (CML), pentosidine, and fluorescent AGEs of chicken meatballs with GLP decreased by 11.1%, 22.3%, 19.5%, 4.30%, 8.66%, 8.27%, 4.80%, 20.5%, and 7.68%, respectively; while free sulfhydryl groups the content increased by 4.90%. Meanwhile, there was no significant difference between meatballs with GLP and TP in AV, A294, GO, and CML (p > 0.05). Correlation analysis indicated that GO, CML, pentosidine, and fluorescent AGEs positively correlated with AV, TBARS, A294, and A420, while GO, CML, pentosidine, and fluorescent AGEs negatively correlated with free sulfhydryl groups. These results manifested GLP could inhibit AGEs formation by inhibiting lipid oxidation, protein oxidation, and Maillard reaction. The possible inhibitory mechanism of GLP on the AGEs included scavenging free radicals, capturing dicarbonyl compounds, forming polyphenol–protein compounds, and reducing the formation of glucose. Therefore, the work demonstrated that the addition of plant polyphenols may be a promising method to inhibit AGEs formation in food

Properties and photosynthetic promotion mechanisms of artificial humic acid are feedstock-dependent

Abstract The artificial humic acids (AHA) approach contributes to achieving the carbon (C) emission peaking and neutrality goal through efficient recycling of waste biomasses and promotion of plant photosynthesis. However, the dependence of their production processes and photosynthetic promotion mechanisms on feedstocks remains unclear. In this study, waste biomasses including camphor leaves (CL), corn stalks (CS), peanut shells (PS), and mixed cyanobacteria (MC) have been respectively converted into artificial humic acids through an environmentally friendly hydrothermal humification approach. The dynamic humification process of different feedstocks and the composition, structural properties, and electron transfer capacity of AHA products were determined. Moreover, the different AHA products were applied to corn to explore their respective photosynthetic promotion mechanisms. High relative contents of lignin and C/N in feedstocks are not conducive to the formation of photodegradable substances and the redox property in AHA. The application of AHA increased the net photosynthetic rate and biomass C of corn by 70–118% and 22–39%, respectively. The AHA produced from higher H/C (0.19) and hemicellulose content (17.09%) in feedstocks (e.g., MC) increased corn photosynthesis by improving light energy capture and conversion efficiency in the PSII process. In contrast, the AHA produced from a higher content of lignin (19.81%) and C/N (7.67) in feedstocks (e.g., CS) increased corn photosynthesis by providing functional enzymes (proteins) and nutrients for leaves. This work provides new insights into the utilization of renewable resources, and the artificial humic acids approach sheds light on environmental sustainability by constructing a closed loop of C in environments. Graphical Abstrac

Accurate and Rapid Extraction of Aquatic Vegetation in the China Side of the Amur River Basin Based on Landsat Imagery

Since the early 1950s, the development of human settlements and over-exploitation of agriculture in the China side of the Amur River Basin (CARB) have had a major impact on the water environment of the surrounding lakes, resulting in a decrease of aquatic vegetation. According to the United Nations Sustainable Development Goals, a comprehensive understanding of the extent and variability of aquatic vegetation is crucial for preserving the structure and functionality of stable aquatic ecosystems. Currently, there is a deficiency in the CARB long-sequence dataset of aquatic vegetation distribution in China. This shortage hampers effective support for actual management. Therefore, the development of a fast, robust, and automatic method for accurate extraction of aquatic vegetation becomes crucial for large-scale applications. Our objective is to gather information on the spatial and temporal distribution as well as changes in aquatic vegetation within the CARB. Utilizing a hybrid approach that combines the maximum spectral index composite and Otsu algorithm, along with the integration of convolutional neural networks (CNN) and random forest, we applied this methodology to obtain an annual dataset of aquatic vegetation spanning from 1985 to 2020 using Landsat series imagery. The accuracy of this method was validated through both field investigations and Google Images. Upon assessing the confusion matrix spanning from 1985 to 2020, the producer accuracy for aquatic vegetation classification consistently exceeded 87%. Further quantitative analysis unveiled a discernible decreasing trend in both the water and vegetation areas of lakes larger than 20 km2 within the CARB over the past 36 years. Specifically, the total water area decreased from 3575 km2 to 3412 km2, while the vegetation area decreased from 745 km2 to 687 km2. These changes may be attributed to a combination of climate change and human activities. These quantitative data hold significant practical implications for establishing a scientific restoration path for lake aquatic vegetation. They are particularly valuable for constructing the historical background and reference indices of aquatic vegetation

Research Progress in the Multilayer Hydrogels

Hydrogels have been widely used in many fields including biomedicine and water treatment. Significant achievements have been made in these fields due to the extraordinary properties of hydrogels, such as facile processability and tissue similarity. However, based on the in-depth study of the microstructures of hydrogels, as a result of the enhancement of biomedical requirements in drug delivery, cell encapsulation, cartilage regeneration, and other aspects, it is challenge for conventional homogeneous hydrogels to simultaneously meet different needs. Fortunately, heterogeneous multilayer hydrogels have emerged and become an important branch of hydrogels research. In this review, their main preparation processes and mechanisms as well as their composites from different resources and methods, are introduced. Moreover, the more recent achievements and potential applications are also highlighted, and their future development prospects are clarified and briefly discussed