Study of slope length (L) extraction based on slope streamline and the comparison of method results.

Slope length is an important factor in soil erosion modeling, and the reasonable automatic extraction of slope length is of great significance in soil erosion research. However, previous studies have mainly focused on the regional scale, and how to effectively extract slope length at the slope scale deserves further research. In this study, a slope length extraction algorithm based on slope streamlines method (SSM) is proposed for the slope length extraction problem in geomorphology, and it is compared with three existing slope length calculation methods. The experimental results show that the new method can quickly calculate the length of slope streamlines, and the extracted slope lengths have better accuracy; the coefficients of determination demonstrates a better overall fitting effect of the four extraction methods, with coefficients of determination exceeding 0.7; this indicates that the use of SSM has similar accuracy and stability to other methods in calculating slope lengths. Among all the calculation methods, SSM has a better overall fitting effect for slope length calculation, and the obtained slope length value domain range is relatively small and concentrated in a small range, which expresses the slope length better.

Template-Free Synthesis and Multifunctional Application of Foam HKUST-1.

Hierarchically porous metal-organic frameworks (HP-MOFs) have attracted a lot of attention in recent years because their hierarchical pores have critical importance in strengthening their performance, including guest diffusion kinetics, catalytic activity, and selectivity, especially with reference to large molecules. However, the preparation method for simple, controllable, and stable HP-MOFs at a micro-/meso-/macroscopic scale is still lacking. Herein, we showed several forms of HKUST-1 (HKUST = Hong Kong University of Science and Technology) by simply changing the copper source and solvent type, including original micron HKUST-1 (O-HKUST-1), half-foam HKUST-1 (HF-HKUST-1), and fully foam HKUST-1 (F-HKUST-1). Compared to O-HKUST-1, HF-HKUST-1 and F-HKUST-1 possessed an apparent hierarchically porous structure due to the high fusion of HKUST-1 nanocrystals. Especially in F-HKUST-1, all of the HKUST-1 nanocrystals were tightly integrated into each other, which formed a holistic hollow foam structure. Hence, F-HKUST-1 exhibited the highest adsorption capacity toward large molecules, including proteases, phosphotungstic acid, and organic dyes. Meanwhile, F-HKUST-1 presented the highest photocatalytic degradation capability for rhodamine B. Furthermore, F-HKUST-1, loaded with phosphotungstic acid (F-HKUST-1@PTA), which was used as a catalyst, indicated a catalytic capacity comparable to that of a homogeneous catalyst (pure phosphotungstic acid).

Evaluation of DEM Accuracy Improvement Methods Based on Multi-Source Data Fusion in Typical Gully Areas of Loess Plateau.

Improving the accuracy of DEMs is a critical goal in digital terrain analysis. The combination of multi-source data can be used to increase DEM accuracy. Five typical geomorphic study areas in the Loess Plateau in Shaanxi were selected for a case study and a 5 m DEM unit was used as the basic data input. Data from three open-source databases of DEM images, the ALOS, SRTM and ASTER, were obtained and processed uniformly through a previously geographical registration process. Three methods, Gram-Schmidt pan sharpening (GS), weighted fusion and feature-point-embedding fusion, were used for mutual enhancement of the three kinds of data. We combined the effect of these three fusion methods in the five sample areas and compared the eigenvalues taken before and after the fusion. The main conclusions are as follows: (1) The GS fusion method is convenient and simple, and the three combined fusion methods can be improved. Generally speaking, the fusion of ALOS and SRTM data led to the best performance, but was greatly affected by the original data. (2) By embedding feature points into three publicly available types of DEM data, the errors and extreme error value of the data obtained through fusion were significantly improved. Overall, ALOS fusion resulted in the best performance because it had the best raw data quality. The original eigenvalues of the ASTER were all inferior and the improvement in the error and the error extreme value after fusion was evident. (3) By dividing the sample area into different areas and fusing them separately according to the weights of each area, the accuracy of the data obtained was significantly improved. In comparing the improvement in accuracy in each region, it was observed that the fusion of ALOS and SRTM data relies on a gentle area. A high accuracy of these two data will lead to a better fusion. Merging ALOS and ASTER data led to the greatest increase in accuracy, especially in the areas with a steep slope. Additionally, when SRTM and ASTER data were merged, the observed improvement was relatively stable with little difference.

Magnetic properties of a soft magnetic elastomer based on antioxidant magnetic composite particles and a water-soluble polymer matrix.

A soft magnetic elastomer, called a magnetorheological elastomer (MRE), based on a polyacrylamide (PAM) modified carbonyl iron particle (P-CIP) composite and a water-soluble PAM matrix was designed and prepared by the chemical polymerization and crosslinking method. P-CIPs were synthesized by the polymerization of an acrylamide monomer on the CIP surface to improve the oxidation resistance of CIPs and the interaction between the particles and polymer matrix in the MRE. The results obtained from infrared spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) (in a nitrogen atmosphere) show that the coating effect of the polymer on the particle surface is very good. TGA (in an air atmosphere) curves indicate that the P-CIPs show strong oxidation resistance. Meanwhile, the test results obtained for the magnetic properties show that the MRE with P-CIPs has a saturation magnetization (94.7 emu g-1), a relative magnetorheological effect (687.5%), and a Payne effect factor (92%) under the action of a strong magnetic field (1 T). It was also clearly found that these properties are enhanced with increasing magnetic field intensity. Furthermore, the chain effect of magnetic particles under a magnetic field, the strong particle-matrix interaction and its breakdown process with increasing shear strain were discussed in this work.

An all-in-one strategy for municipal solid waste incineration fly ash full resource utilization by heat treatment with added kaolin.

Resourcization has become a popular research topic for the final disposal of municipal solid waste incineration fly ash (MSWI FA). However, the current research is limited to building material preparation or valuable chloride recovery, which may cause resource waste and secondary pollution. A unique process, heat treatment with the addition of kaolin (KL), was presented to achieve complete resource utilization of MSWI FA. The physical properties of ceramsite could be improved by adding KL, and dioxin removal, heavy metals, and valuable chloride separation could be achieved via sintering at 1150 °C. The separation and purification of dust carried by the flue gas during thermal treatment (secondary fly ash) was achieved via wet separation. A building ceramsite with a compressive strength of 24.8 MPa was obtained, whereas dioxin and heavy metal toxicity were far below the standard limits. Heavy metal content was enriched by 12 times, approximately 59.6%, achieved after secondary fly ash separation and purification. A heavy metal product containing 39.5% Zn, 19.1% Pb, and chloride salt containing 41.8% KCl were obtained. This showed a high potential for the developed process to separate multiple valuable elements from ashes. This novel process will further promote the development and application of harmless and resourceful technologies for MSWI FA.

A Multi-Criteria Framework for Identification of Gully Developmental Stages Based on UAV Data-A Case Study in Yuanmou County, Yunnan Province, SW China.

Gully erosion is a common form of soil erosion in dry-hot valleys, and it often brings serious land degradation. A multi-criteria method integrating the characteristics of the longitudinal profile (LP), the cross profile (CP) and the knickpoints of gullies was applied to identify the development stage of gullies in Yuanmou County, Yunnan Province, in southwestern China. Firstly, based on the high-resolution data sources produced by an unmanned aerial vehicle (UAV), 50 gullies were selected as the typical ones in Tutujiliangzi and Shadi village. The LPs were extracted, and their morphological indices, information entropy and fitting functions were calculated. The morphological characteristics of the CPs and the presence or absence of knickpoints were recorded. The results show that the period of the gullies in Tutujiliangzi and Shadi is dominated by the deep incision period and the equilibrium adjustment period, which means that most gullies are in the period of the severe erosion stage. Among the gullies, 13 LPs' morphological index is between 0.636 and 0.933, and the morphology of the LP presents an upward convex shape; the cross profiles are mainly V-shaped and U-shaped. Thirty-two LPs' morphological index is between 1.005~2.384, which presents a slightly concave shape; the cross profiles are mainly repeated U-shapes. The remaining five LPs have a morphological index of 0.592, 0.462, 1.061, 1.344 and 0.888, respectively; the LPs of upstream and downstream are different. The LPs of the Tutujiliangzi gullies are nearly straight lines and slightly concave, while those of the Shadi village gullies are convex and nearly straight lines. The knickpoints and step-pools in Shadi village are more developed, while the gullies in Tutujiliangzi develop more rapidly. This study shows that in counties with similar conditions, these conditions such as temperature and precipitation, local topographic changes, soil properties and vegetation conditions have obvious effects on the development of gullies.

Nanofused Hierarchically Porous MIL-101(Cr) for Enhanced Methyl Orange Removal and Improved Catalytic Activity.

Hierarchically porous MIL-101(Cr) (H-MIL-101(Cr)) with meso/macro-pores was directly prepared via nanofusion progress by using butyric acid as a modulating agent. In the methyl orange (MO) adsorption experiments, H-MIL-101(Cr) showed a high adsorption capability of 369.8 mg g-1, which was 1.52-fold greater than that of pristine MIL-101(Cr) (P-MIL-101(Cr)). While in the oxidation reaction of indene and 1-dodecene tests, H-MIL-101(Cr) presented much higher catalytic efficiency, with turnover frequency (TOF) values of 0.7242 mmol g-1 min-1 and 0.1492 mmol g-1 min-1, respectively, which were 28% and 34% greater than that in the case of P-MIL-101(Cr). Thus, compared with P-MIL-101(Cr), H-MIL-101(Cr) exhibited better removal efficiency and higher levels of activity in the oxidation reactions of indene and 1-dodecene. The unique structure of H-MIL-101(Cr) also contributed to its superior performance in these processes.

Experimental Study on the Stability of a Novel Nanocomposite-Enhanced Viscoelastic Surfactant Solution as a Fracturing Fluid under Unconventional Reservoir Stimulation.

Fe3O4@ZnO nanocomposites (NCs) were synthesized to improve the stability of the wormlike micelle (WLM) network structure of viscoelastic surfactant (VES) fracturing fluid and were characterized by Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Then, an NC-enhanced viscoelastic surfactant solution as a fracturing fluid (NC-VES) was prepared, and its properties, including settlement stability, interactions between NCs and WLMs, proppant-transporting performance and gel-breaking properties, were systematically studied. More importantly, the influences of the NC concentration, shear rate, temperature and pH level on the stability of NC-VES were systematically investigated. The experimental results show that the NC-VES with a suitable content of NCs (0.1 wt.%) shows superior stability at 95 °C or at a high shear rate. Meanwhile, the NC-VES has an acceptable wide pH stability range of 6-9. In addition, the NC-VES possesses good sand-carrying performance and gel-breaking properties, while the NCs can be easily separated and recycled by applying a magnetic field. The temperature-resistant, stable and environmentally friendly fracturing fluid opens an opportunity for the future hydraulic fracturing of unconventional reservoirs.

The effects of terrain factors on the drainage area threshold: comparison of principal component analysis and correlation analysis.

How and to which extent terrain factors affecting the drainage area threshold (DAT) are disputable. This paper uses principal component analysis (PCA) and correlation analysis to study the influence degree of terrain factors on DAT. Firstly, 22 watersheds, locating in the severe soil erosion region (SSER) of Loess Plateau of China, are picked out as the example areas. The purpose of the mean change point method (MCP) to detect the relationship between DAT and gully density (GD) is to get a reasonable DAT. Secondly, nine terrain factors are calculated, and their statistical values are compared and put in the matrix to clear the different effects on DAT. Finally, the effects of statistical eigenvalues of terrain factors on DAT are compared with PCA and the correlation analysis. According to the PCA, the nine terrain factors are summarized into three principal components, which are slope, height variation, and relief factor. By calculating the score weighted by each factor coefficient matrix and eigenvalue, the result states that slope (S), terrain curvatures (K), and surface roughness (SR) are the factors that have great influence on DAT. Meanwhile, the results of correlation analysis indicate that S, SR, and K have exerted a great influence on the DAT, and the significance level was above 0.05. Both the results of PCA and correlation analysis make clear that the slope is the most direct and influential factor affecting DAT, while other factors are more or less related to slope directly and indirectly. The result implies that the vertical variation of terrain has a strong correlation with the slope, and also has a great influence on DAT. This research not only would be of great significance to recognize the mechanism of gully development, but also able to provide a scientific reference for soil and water conservation in the Loess Plateau.

Experimental Study on the Drag Reduction Performance of Clear Fracturing Fluid Using Wormlike Surfactant Micelles and Magnetic Nanoparticles under a Magnetic Field.

This paper examines a new study on the synergistic effect of magnetic nanoparticles and wormlike micelles (WLMs) on drag reduction. Fe3O4 magnetic nanoparticles (FE-NPs) are utilized to improve the performance of viscoelastic surfactant (VES) solutions used as fracturing fluids. The chemical composition and micromorphology of the FE-NPs were analyzed with FT-IR and an electron microscope. The stability and interaction of the WLM-particle system were studied by zeta potential and cryo-TEM measurements. More importantly, the influences of the temperature, FE-NP concentration, magnetic field intensity, and direction on the drag reduction rate of WLMs were systematically investigated in a circuit pipe flow system with an electromagnetic unit. The experimental results show that a suitable content of magnetic nanoparticles can enhance the settlement stability and temperature resistance of WLMs. A magnetic field along the flow direction of the fracturing fluid can improve the drag reduction performance of the magnetic WLM system. However, under a magnetic field perpendicular to the direction of fluid flow, an additional flow resistance is generated by the vertical chaining behavior of FE-NPs, which is unfavorable for the drag reduction performance of magnetic VES fracturing fluids. This study may shed light on the mechanism of the synergistic drag reduction effects of magnetic nanoparticles and wormlike micelles.

Cost-effectiveness of augmenting universal hepatitis B vaccination with immunoglobulin treatment: a case study in Zhejiang Province, East China.

Objective: To evaluate the cost-effectiveness of the current strategy combining universal vaccination with hepatitis B immunoglobulin (HBIG) treatment for infants of hepatitis B surface antigen (HBsAg) positive mothers compared with universal vaccination with hepatitis B vaccine only.Methods: A decision tree model with a Markov process was constructed and used to simulate the lifetime of the birth cohort in Zhejiang Province during 2016. The current strategy was compared against universal vaccination with respect to costs and health effects. Costs were assessed from the health care system perspective. Health effects were measured by the number of hepatitis B virus (HBV) related diseases and deaths avoided and quality-adjusted life-years (QALYs) gained. The incremental cost­effectiveness ratio (ICER) is calculated and compared to standard willingness-to-pay thresholds. A one-way sensitivity analysis and a probabilistic sensitivity analysis (PSA) were performed to assess parameter uncertainties.Results: Over the cohort's lifetime, 182 acute symptomatic infections, 2215 chronic infections, 872 cases of cirrhosis, 595 cases of hepatocellular carcinoma (HCC) and 1,350 HBV-related deaths among the cohort of 624,000 infants would be further avoided by the current strategy compared to universal vaccination. Universal vaccination was dominated by the current strategy that produced not only higher total QALYs, but also had lower costs. The results remained robust over a wide range of assumptions.Conclusions: The current strategy was cost saving compared to universal vaccination, and continuing the current strategy is recommended to further decrease the burden of hepatitis B.

An economic evaluation of the current measles vaccination program: A case study in Zhejiang Province, east China.

OBJECTIVE: To evaluate the economic impact of the current measles vaccination program in Zhejiang Province, east China. METHODS: A decision tree-Markov model with parameters from published literatures, government documents and surveys was developed and used to simulate over 40 years of a birth cohort in Zhejiang Province during the year 2014. The expected cost and effectiveness of the current measles vaccination program was compared against no vaccination. Costs were assessed from the payer's perspective. Benefits were defined as savings on the direct cost of measles treatment, and the effectiveness was measured according to the number of measles cases and deaths averted. The net present value (NPV), benefit-cost ratio (BCR) and incremental cost-effectiveness ratio (ICER) were also calculated. A threshold for cost-effectiveness of less than 3 times the Gross Domestic Product (GDP) per capita was used. One-way sensitivity analysis was performed to assess parameter uncertainties. RESULTS: The total vaccination cost was estimated to be $2.52 million. The BCR of the current measles program was found to be 6.06 with a NPV of $73.38 million. It was also calculated that a total of 195,165 measles cases and 191 measles-related deaths would be prevented by vaccination. The ICER was approximately $12.91 per case averted and $13,213.43 per death averted, respectively, which was cost-effective. The models were proven to be robust. CONCLUSIONS: The current measles vaccination program appeared to be cost-effective and to offer substantial benefits. The results of this analysis sought to contribute to the justification of future investments to achieve the goal of measles elimination.

Joint associations of smartphone use and gender on multidimensional cognitive health among community-dwelling older adults: a cross-sectional study.

BACKGROUND: Smartphone use has become an increasingly pervasive part of our daily lives, and as a portable media device, smartphones provide good support for cognitive training during aging. However, little is known about the joint association of smartphone use and gender on the cognitive health of older adults, particularly with regard to multi-domain cognition. METHODS: A face-to-face survey of 3230 older adults aged 60+ years was conducted in Xiamen, China, in 2016. The Montreal Cognitive Assessment (MoCA) score was used to measure both general and multi-domain cognition. Smartphone use was self-reported and the number of the smartphone functions used (NSFU) was classified as 0, 1, and 2+. General and subdomain cognitive functions were modelled on NSFU only, gender only, and NSFU and gender combined by using a series of proportional-odds cumulative logit models. Furthermore, joint associations of gender and NSFU on both general and multi-domain cognition were estimated, and a four-category quantile classification was used to evaluate the total MoCA score. RESULTS: Among all 3230 respondents, 2600 remained after exclusion of respondents with very low MoCA scores (below the education-adjusted cut-offs for dementia). Only 29.96% of older adults used smartphones, 473 (60.72%) of which were men. Respondents who had a higher NSFU maintained a better general and sub-domain cognition except for memory and orientation. Although women had lower values compared to men in visuospatial ability (OR (95% CI): 0.46 (0.37-0.57)), they outperformed their male counterparts in memory (OR (95% CI): 1.38 (1.10-1.73)). The results of the joint association showed that women's inferiority in visuospatial ability diminished when they had a NSFU of 2+. However, a significantly better improvement in memory for male was achieved when they had a NSFU of 1 rather than 2 + . CONCLUSIONS: A higher NSFU was positively associated with increased general and partial subdomain cognitive functions. However, gender differences were found in visuospatial ability and memory, which could be alleviated by smartphone use.