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The properties and appearance of ancient architectural red sandstone will be damaged after being eroded by the natural environment for a long time. In order to investigate the weathering and erosion characteristics of the red sandstone structure of an existing ancient building, ultrasonic testing techniques, combined with scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray computed tomography (X-CT), were used to analyze a building in Ganzhou. The variation in chemical substances contained in the red sandstone specimens according to phenology was analyzed by X-ray diffraction (XRD). The characteristic parameters of the CT grayscale images of the red sandstone were extracted and combined with the ultrasonic wave velocity values to comprehensively analyze the degradation characteristics of the red sandstone specimens, and a method to characterize the degradation degree of the red sandstone as a whole plane is proposed. We use the gray model (GM (1, 1)) to predict the surface degradation degree of red sandstone specimens, and gray relation analysis (GRA) to further analyze the correlation between the characteristic parameters of CT grayscale images of red sandstone and its degradation degree. The results show that in the natural erosion environment, dolomite and chlorite are generated on the exposed surface of the red sandstone, which can protect the internal sandstone to a certain extent. The degradation degree of the red sandstone specimens in the horizontal X and Y directions varies, and the proposed method of calculating the overall plane degradation degree of the red sandstone is feasible. The minimum average relative error of the surface degradation degree obtained from the gray prediction GM (1, 1) model is 1.4591%. There is a good correlation between the characteristic parameters of the red sandstone CT grayscale images and the degradation degree. [ABSTRACT FROM AUTHOR]

Abstract Health assessment for point machines is crucial to the safety of rail systems. The operation of the point machine is a typical multi‐stage process, each with its own characteristic features that allow a health assessment. Therefore, to segment various phases self‐adaptively is quite essential to assess the health state of the point machine. Besides, the degradation of the point machine is characterized as non‐linear. However, these issues are barely discussed when assessing the degradation degree. By converting it into a multi‐classification problem, this paper proposes a novel phase segmentation method based on dimensionless time‐domain features and characteristics of time series by utilizing the adaptive Multiclass Mahalanobis Taguchi System (aMMTS) to segment the signal self‐adaptively. Furthermore, this paper proposes a novel algorithm named Non‐linear Dynamic Time Warping (NLDTW), which modifies the conventional Dynamic Time Warping (DTW) by using a non‐linear distance to overcome the lack of global consistency in the non‐linear degradation assessment. Finally, a modified formula of confidence value is presented to assess the actual degradation degree. The efficiency and feasibility of the proposed framework have been verified by the actual data collected from the point machines of Guangzhou Metro.

Health assessment for point machines is crucial to the safety of rail systems. The operation of the point machine is a typical multi‐stage process, each with its own characteristic features that allow a health assessment. Therefore, to segment various phases self‐adaptively is quite essential to assess the health state of the point machine. Besides, the degradation of the point machine is characterized as non‐linear. However, these issues are barely discussed when assessing the degradation degree. By converting it into a multi‐classification problem, this paper proposes a novel phase segmentation method based on dimensionless time‐domain features and characteristics of time series by utilizing the adaptive Multiclass Mahalanobis Taguchi System (aMMTS) to segment the signal self‐adaptively. Furthermore, this paper proposes a novel algorithm named Non‐linear Dynamic Time Warping (NLDTW), which modifies the conventional Dynamic Time Warping (DTW) by using a non‐linear distance to overcome the lack of global consistency in the non‐linear degradation assessment. Finally, a modified formula of confidence value is presented to assess the actual degradation degree. The efficiency and feasibility of the proposed framework have been verified by the actual data collected from the point machines of Guangzhou Metro. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis of hen egg confers beneficial functionalities, but it is essential to control the progress of hydrolysis to enhance the quality and reduce allergy risk. However, a reliable method for directly controlling the progress of egg protein hydrolysis is unavailable. Focusing on ovalbumin, a major protein and allergen in egg white, we demonstrated the applicability of liquid chromatography–tandem mass spectrometry (LC–MS/MS) to assess the degradation of ovalbumin in its enzymatic hydrolysates. Using immobilized Alcalase or Everlase, the degradation degree (DD) of ovalbumin was determined using LC–MS/MS; the result (8.8–95.3%) was highly correlated with the DD (8.9–92.3%) obtained using size-exclusion chromatography (SEC-HPLC) (r > 0.96, p < 0.001). In egg white hydrolysates with a DD of 16.1–99.5%, ovalbumin recovery when spiked with 1250 ng/mL was 81.1–114.8% with excellent dilution linearity (r2 > 0.99). These results indicate that LC–MS/MS is a reliable method for increasing the quality of enzymatically hydrolyzed egg products for food, nutraceutical, pharmaceutical, and cosmetic industries. [ABSTRACT FROM AUTHOR]

Hydropower, wind power, and photovoltaic power generation are the most common clean energy sources and are important ways to achieve “carbon neutrality” and “carbon peak”. With the adjustment of China’s energy structure, wind power and photovoltaic power generation have entered the peak period of development, but the above two forms of power generation have a certain degree of instability, which has increased the risk of safe and stable operation of the power grid. In contrast, hydroelectric power generation has good stability, and giving full play to the excellent peak and frequency modulation functions of hydro-generator sets is of great significance to ensuring the safe and stable operation of the power grid. This requires the hydro-generator unit to have good reliability during the service period. Through the evaluation of the unit’s health status, the unit’s health status can be predicted, and the maintenance strategy can be given to eliminate the fault in the budding state. This article summarizes the health status assessment methods of hydro-turbine generator sets, and puts forward five health status levels: “healthy”, “good”, “attention”, “abnormal” and “dangerous”. This paper has carried out a quantitative calculation on the health status of a certain hydraulic turbine. The results show that the degree of health of the turbine is “healthy”, “good”, “attention”, “abnormal” and “dangerous” respectively and the degrees are 0.065, 0.632, 0.279, 0.024, 0. According to the principle of maximum membership, it can be judged that the turbine is in “good” status. The evaluation result is consistent with the actual operation of the unit, indicating that the evaluation method studied in this paper has a certain practicability and can provide scientific guidance for the health evaluation of the hydroelectric generating unit.

Copyright of Advances in Earth Science (1001-8166) is the property of Advances in Earth Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The properties and appearance of ancient architectural red sandstone will be damaged after being eroded by the natural environment for a long time. In order to investigate the weathering and erosion characteristics of the red sandstone structure of an existing ancient building, ultrasonic testing techniques, combined with scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray computed tomography (X-CT), were used to analyze a building in Ganzhou. The variation in chemical substances contained in the red sandstone specimens according to phenology was analyzed by X-ray diffraction (XRD). The characteristic parameters of the CT grayscale images of the red sandstone were extracted and combined with the ultrasonic wave velocity values to comprehensively analyze the degradation characteristics of the red sandstone specimens, and a method to characterize the degradation degree of the red sandstone as a whole plane is proposed. We use the gray model (GM (1, 1)) to predict the surface degradation degree of red sandstone specimens, and gray relation analysis (GRA) to further analyze the correlation between the characteristic parameters of CT grayscale images of red sandstone and its degradation degree. The results show that in the natural erosion environment, dolomite and chlorite are generated on the exposed surface of the red sandstone, which can protect the internal sandstone to a certain extent. The degradation degree of the red sandstone specimens in the horizontal X and Y directions varies, and the proposed method of calculating the overall plane degradation degree of the red sandstone is feasible. The minimum average relative error of the surface degradation degree obtained from the gray prediction GM (1, 1) model is 1.4591%. There is a good correlation between the characteristic parameters of the red sandstone CT grayscale images and the degradation degree.

A fuzzy hierarchical comprehensive evaluation algorithm including fuzzy matrix and comprehensive evaluation matrix calculation thought is proposed to accurately evaluate the running state of an electromechanical system. The analytic hierarchy process is included in the algorithm, which calculates the state of each subsystem from top to bottom and the states are used as the evaluation factor of the upper system. The idea of degradation degrees is introduced to standardize the indicators. The paper carried out the simulation experiment for the electromechanical system with a model number of JKMD-4 × 4(Z). The experimental results show that the established state evaluation model can accurately judge the operation state of the system with not too much data.

The performance degradation of combined rotor with crack of the disk is one of the significant reasons which cause malfunctions and accidents of gas turbine,while rules of performance degradation are still unclear. By using the finite element ANSYS platform to establish the combined rotor model,the dynamic analysis of the combined rotor with the crack in disk was conducted. The rules of performance degradation of combined rotor were obtained through defining degradation degree parameters. The rules of the performance degradation of combined rotor with crack in disk were verified experimentally. The results show that the performance degradation of combined rotor is extremely slow in the stable degradation stage,the significant transition point which leads to accidents occurs when the degradation reaches a certain extent. The different temperatures,rotation rate,ratios of crack depth to length and positions of the crack in disk have great influence on the degradation of combined rotor.

In this work, a recoverable acrylamide-vinylamine copolymer immobilized TEMPO [P(AM-co-VAm)-T] catalyst for selective oxidation of cellulose with good catalytic performance and low cellulose degradation was developed. Firstly, the acrylamide-vinylamine copolymer [P(AM-co-VAm)] was prepared by Hofmann degradation of polyacrylamide (PAM). Then, the condensation reduction reaction between amine groups of P(AM-co-VAm) and carbonyl groups of 4-oxo-TEMPO yielded P(AM-co-VAm)-T. P(AM-co-VAm)-T was used as a catalyst for selective oxidation of C6 primary hydroxyl groups of cellulose to carboxyl groups. The carboxyl content of obtained oxidized cellulose was up to 1.114 mmol/g, which was equivalent to 76% of the free TEMPO level. This macromolecular catalyst was easily recycled and the recycling performance was excellent. Interestingly, it was found that P(AM-co-VAm)-T could effectively reduce the degradation of oxidized cellulose. The corresponding degradation degree was 21–27%, which was much lower than the degradation degree of free TEMPO (61–66%) and other macromolecular TEMPO catalysts, such as polyacrylic acid immobilized-TEMPO (41–53%) and polyamidoamine supported TEMPO (28–44%). P(AM-co-VAm)-T with positive charge and suitable size could effectively inhibit the formation of C6 aldehydes and C2/C3 ketones, which was the main reason that it could significantly inhibit cellulose degradation. [ABSTRACT FROM AUTHOR]

A fuzzy hierarchical comprehensive evaluation algorithm including fuzzy matrix and comprehensive evaluation matrix calculation thought is proposed to accurately evaluate the running state of an electromechanical system. The analytic hierarchy process is included in the algorithm, which calculates the state of each subsystem from top to bottom and the states are used as the evaluation factor of the upper system. The idea of degradation degrees is introduced to standardize the indicators. The paper carried out the simulation experiment for the electromechanical system with a model number of JKMD-4 × 4(Z). The experimental results show that the established state evaluation model can accurately judge the operation state of the system with not too much data. [ABSTRACT FROM AUTHOR]

In order to improve the accuracy of reliability assessment for the system with multiple failure modes, a reliability modeling method based on the s-dependent competing risk of degradation failures and traumatic failures was proposed. A condition space model was applied to evaluate the degradation degree of system by fusing multivariate degradation data, and then Gamma process was utilized to establish the degradation failure model of system. A conditional Weibull distribution was used to establish the traumatic failure model of system. The reliability model based on dependent competing risk was established by assuming that the probability of traumatic failure depends on the degradation degree of system. An illustrative example was provided to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Purpose: Molecular organic markers are an effective tool to detect the adverse effects of anthropogenic inputs in the aquatic environment. Linear alkylbenzenes (LABs) are sewage molecular organic markers that are released into the environment as a consequence of the incomplete sulphonation step of industrial detergents. In the current work, the characterisation, sources and degradation of LABs in the surface sediments of Muar River and Johor Bahru Coast, Malaysia, were identified. Materials and methods: The surface sediment samples were obtained from the Muar River and Johor Bahru Coast area using an Ekman dredge sampler. Both locations were selected to represent the current anthropogenic pollution situation. The sediment samples were subjected to Soxhlet extraction, first purification step, second fractionation step column chromatography and then gas chromatography-mass spectrometry (GC-MS) analysis. Results and discussion: The results revealed that the LAB concentrations in the samples of the Muar River and Johor Bahru Coast ranged from 87.4 to 188.1 ng g−1 dry weight (dw) and from 87.6 to 188.7 ng g−1 dw, respectively. The ratios of internal isomer (the benzene ring is closed to the centre of the linear alkyl chain) to external isomer (the benzene ring nears the end of the linear alkyl chain) (I/E ratio) of LABs were between 1.7 and 2.2 in Muar River and between 1.8 and 2.7 in Johor Bahru Coast samples. Conclusions: These findings indicate that the concentrations of LABs in the sediments ranged from low to moderate contamination and the aquatic environment received both primary and secondary sewage effluents. This study emphasises that continuous monitoring of sewage pollution to minimise the environmental pollution in coastal areas is highly recommended. [ABSTRACT FROM AUTHOR]

It is expected, the growing demand for supercapacitor energy storage system (ESS) in which thousands of supercapacitor cells are connected as a stack for meeting the desired load power. The lifetime of ESS dramatically depends on the operating thermal effects of individual cells. In this paper, a temperature-suppression charging strategy is proposed for supercapacitor ESS to maximize its lifetime. First, the charging current and equivalent series resistance (ESR) construct the supercapacitor thermal model, and the ESR represents the degradation degree of the supercapacitor. Second, the maximization of system lifetime and equalization of unit degradation degree jointly form a convex optimization problem with the charging time constraint. The optimization problem is solved to obtain the equivalent charging current, which is realized through pulse width modulation (PWM) digital control. Simulation and experimental results show that the proposed method has the advantages of reducing ESS operating temperature and maximizing its lifetime. [ABSTRACT FROM AUTHOR]

In view of the problems of degradation index construction and predicted lag of similarity-based methods, a degradation degree considered method for remaining useful life prediction based on similarity is proposed. The effectiveness of the proposed method is demonstrated by using turbofan engine data from NASA and a real case study. [ABSTRACT FROM AUTHOR]

Remaining useful life (RUL) prediction is an effective method to ensure system safety and avoid catastrophe in applied intelligent perspective. A similarity-based method for RUL prediction based on operational reliability has been proposed in this paper to overcome the shortcomings existing in the conventional similarity-based RUL prediction method of devices. The first shortcoming is the construction difficulty of degradation index (DI) and the second shortcoming is the low accuracy of similarity measurement. First, a novel operational reliability fused index (ORI) was proposed by calculating offset distance and offset angle between current state and normal state of devices, and the index was used as the DI for life prediction. Then, a multi-factor similarity measurement method was proposed to select the most similarity samples and a novel similarity measurement and weight assigned method considering degradation degree was proposed based on the previous similarity measurement. Finally, the RUL was weighted predicted. The effectiveness of the proposed method was validated by implementing two cases. [ABSTRACT FROM AUTHOR]

A new detachable packing screen used for sand control in oilfields has been designed. The key technology is to achieve rapid and effective downhole detachment of PLA-T (a polylactic acid material) tubing. An optimal formulation of the degradation agent was proposed considering the degradation degree and degradation rate of PLA-T materials. The temperature, salt and dilution tolerance of such degradation agent was evaluated under conditions simulating the in-situ reservoir environment. The degradation mechanism of the PLA-T was analyzed through scanning electron microscope (SEM) on the PLA-T surface during the reaction process. It is shown that the optimal formulation is that acetone: dimethylformamide: ethylenediamine ratio equals to 3: 2: 5. Under reservoir conditions with temperatures from 50 °C to 80 °C, water salinities from 10,000 mg/L to 100,000 mg/L and diluted concentrations from 70% to 90% of the original concentration, the degradation time of the PLA-T tubing ranges from 6 min to 92 min. This system maintains its excellent degradation capability under the complex downhole situation. The SEM tests show that the surface structure of the PLA-T changes gradually from the smooth surface, to cracks, then fractures, irregular fractures and finally the fracture-hole structure, and correspondingly the degradation rate of PLA-T first increases and then drops. The proposed high-efficiency degradation agent can achieve effective detachment of the downhole packing screen by rapidly degrading the PLA-T tubing, which enables screenless sand control of the unconsolidated sandstone reservoirs. [ABSTRACT FROM AUTHOR]

The degradation of rapeseed oil methyl ester (RME) under accelerated conditions was investigated by use of total fluorescence spectroscopy (TFS). This technique provides an easy and quick analysis of natural antioxidants (e.g. vitamin E, chlorophylls, etc.) and of oxidation products (e.g. hydroperoxides and oligomers) of RME at their characteristic excitation and emission wavelengths. In the result it was proven that similar to the specification related Rancimat-test (EN 14112) the oxidation stability of RME could be determined by fluorescence signals of the oxidation products. Additionally a quick and direct determination of the degradation degree and the oxidation stability of RME by fluorescence spectroscopy is enabled by use of the correlation between the Rancimat- and the fluorescence-measurement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study determines the early deterioration condition of critical components for a wind turbine generator system (WTGS). Due to the uncertainty nature of the fluctuation and intermittence of wind, early deterioration condition evaluation poses a challenge to the traditional vibration-based condition monitoring methods. Considering the its thermal inertia and strong anti-interference capacity, temperature characteristic parameters as a deterioration indication cannot be adequately disturbed by the uncontrollable noise and uncertainty nature of wind. This paper provides a probability evaluation method of early deterioration condition for critical components based only on temperature characteristic parameters. First, the dynamic threshold of deterioration degree function was proposed by analyzing the operational data between temperature and rotor speed. Second, a probability evaluation method of early deterioration condition was presented. Finally, two cases showed the validity of the proposed probability evaluation method in detecting early deterioration condition and in tracking their further deterioration for the critical components. [ABSTRACT FROM AUTHOR]

In this article, we deal with optimal preventive maintenance policies based on online condition monitoring. The failure rate function is important for maintenance decisions. Two concepts of failure are proposed and the computing method based on condition monitoring data is given. Both un-repairable and repairable equipment are taken into consideration. For repairable equipment, the degree of degradation and failure rate will decrease after maintenance. The result of the simulation shows that taking the two types of failure rate functions into account will make the expected cost rate less than the classical method. So we draw a conclusion that the two types of failure rate functions are advantageous in maintenance decisions. [ABSTRACT FROM AUTHOR]

This document describes processing basic measurement signals, which were used in test sequence with different coders. The determination of degradation degree of these signals and the elimination of these coders influences on these signals was the aim of this paper. At the end of this paper the test sequence is defined. We can use this sequence for intrusive measurement VTQoS in the networks, using the coders with lower transfer rate.

The qualitative description of rock masses by means of classification systems and subsequent correlation to establish engineering quantities or design parameters has become one of the most challenging topics in rock engineering. Many rock mass classification systems have been proposed for rock masses with the consideration of a particular rock structure and/or specific purposes. Therefore, direct utilization of these systems, in their original form, for the characterization of complex rock mass conditions is not always possible. This is probably one of the reasons why rock engineers continue to develop new systems or modify and extend current ones. The recent tendency is to obtain rock mass properties from the utilization of properties of intact rock and rock classification indexes, which have some drawbacks. In this study, it is aimed to propose a new rock mass quality rating system designated as Rock Mass Quality Rating (RMQR). This new rock mass rating system is used to estimate the geomechanical properties of rock masses. In the first part of this paper, the input parameters of RMQR and their ratings are given and discussed. In the second part, the unified formula proposed by the first author is adopted for the new rock mass rating system for estimating the rock mass properties and compared with the results of the in situ tests carried out in Japan and those estimated from some empirical relationships developed by other investigators, and the outcomes of these studies are presented and discussed. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The degradation of salicylic acid (SA) was carried out utilizing classical Fenton reagents and modified Fenton with ferric iron salt and goethite as source of iron catalyst. The efficiency of the treatments was evaluated on the basis of SA degradation degree, COD and BOD reduction. Due to the tendency of SA to form complexes with ferric iron, decreasing the concentration of catalyst and increasing that of hydrogen peroxide intensified SA degradation by the classical Fenton process. Application of Fe3+/H2O2 led to the same SA degradation degree as classical Fenton process with the following termination, where the entire residual SA is complexed with Fe3+. SA degradation by modified Fenton was intensified with higher goethite concentration and in acidic pH conditions. The addition of UV-irradiation did not improve the action of the Fenton''s/modified Fenton''s reagent system. Overall COD and BOD removal efficiency comprised nearly 90% under optimal treatment conditions applied. [Copyright &y& Elsevier]

A landfill is an important sink of plastic waste and potential sources of microplastics (MPs) when mineralized refuse is reused. However, limitations are still present in quantifying MPs in mineralized refuse and assessing their degradation degree. In this study, laser direct infrared spectroscopy and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to identify MPs of mineralized refuse from a landfill. Although 25-113 items/g MPs were detected in particles subjected to flotation, 37.9-674 μg/g polyethylene terephthalate (PET) and 0.0716-1.01 μg/g polycarbonate (PC) were detected in the residual solids by LC-MS/MS, indicating a great amount of plastic polymers still presented in the residue. This suggests that the commonly used flotation-counting method will lead to significant underestimation of MP pollution in mineralized refuse, which might be due to the aging and aggregation process caused by the long-term landfill process. The ratio of "bisphenol A/PC" and "plasticizer/MPs" was found to be positively correlated and negatively correlated with the landfill age, respectively. Therefore, in addition to the spectral index such as the carbonyl index, new indexes based on the concentrations of polymers, free monomers, and plasticizers were proposed to characterize the degradation degree of MPs in a landfill.

This study is aimed at increasing the performance and reliability of silicon-based heterojunction solar cells with advanced methods. This is achieved by a numerical electro-optical modeling and reliability analysis for such solar cells correlated with experimental analysis of the Cu2O absorber layer. It yields the optimization of a silicon tandem heterojunction solar cell based on a ZnO/Cu2O subcell and a c-Si bottom subcell using electro-optical numerical modeling. The buffer layer affinity and mobility together with a low conduction band offset for the heterojunction are discussed, as well as spectral properties of the device model. Experimental research of N-doped Cu2O thin films was dedicated to two main activities: (1) fabrication of specific samples by DC magnetron sputtering and (2) detailed characterization of the analyzed samples. This last investigation was based on advanced techniques: morphological (scanning electron microscopy—SEM and atomic force microscopy—AFM), structural (X-ray diffraction—XRD), and optical (spectroscopic ellipsometry—SE and Fourier-transform infrared spectroscopy—FTIR). This approach qualified the heterojunction solar cell based on cuprous oxide with nitrogen as an attractive candidate for high-performance solar devices. A reliability analysis based on Weibull statistical distribution establishes the degradation degree and failure rate of the studied solar cells under stress and under standard conditions. [ABSTRACT FROM AUTHOR]

• Formaldehyde comes from overoxidation of C-6 on CMC reducing glucose residue. • Glucose produced from CMC degradation is the other source of formaldehyde in DCMC. • Lowering degradation degree and raising DS can reduce formaldehyde in DCMC. • SA with carboxyl on C-6 of each unit does not form formaldehyde during oxidation. Formaldehyde was detected in dialdehyde carboxymethyl cellulose (DCMC) tanning agent prepared through periodate oxidation of sodium carboxymethyl cellulose (CMC). Formaldehyde was then introduced into leather through DCMC tanning, which poses a potential risk to human health. The formation mechanism of formaldehyde in DCMC was investigated by composition analysis and intermediate identification of DCMC with different polymerization degrees and sugar unit structures. Formaldehyde was derived from the overoxidation of C-6 on the reducing glucose residue of CMC. Moreover, glucose was produced from the concomitant degradation of CMC during oxidation, and then oxidized to liberate formaldehyde. The low degradation degree and high degree of substitution of CMC reduced the possibility of the formation of reducing glucose residue and glucose during oxidation, thereby resulting in low formaldehyde content in DCMC and DCMC-tanned leather. These findings serve as a foundation for the minimization of formaldehyde in DCMC and the development of ecological tanning approach. [ABSTRACT FROM AUTHOR]

• Degradation severity lessens from central denudated patches to their periphery. • Soil moisture, density and root volume decrease with degradation severity. • Soil nutrient content and mechanical strength decrease as degradation worsens. Grassland degradation is an important cause of soil erosion and environment degradation in the world. So far few have quantitatively analyzed how the level of soil degradation of grassland affects the physical, chemical and mechanical traits of topsoil in the grassland, as well as the resistance of the surface root-soil composite to erosion. This paper attempts to fill this knowledge gap by studying the impact of soil degradation triggered by rodents with the advent of denudated patches on alpine meadow topsoil on the Qinghai-Tibet Plateau in west China. Field samples were collected at 0–2 cm to test soil nutrients, physical and mechanical properties, and samples collected at 0–5 cm depth were used to test the three-dimensional pore structure of the root-soil composite in different denudated patches. A combination of macroscopic and microscopic experiments was used to study the impacts of differently degraded meadows on topsoil properties and thereby the ecological environment. Results showed that the severity of soil degradation lessened gradually from the center of the denudated patches to the periphery. Soil moisture, density and root volume in the severely degraded zone were significantly lower than in moderately and mildly degraded ones. The volumetric porosity ratio of severely degraded meadows is 4.65% and 9.55% higher than that of moderately and slightly degraded meadows, respectively, The average surface porosity increased by 4.37 and 9.58%, respectively, the average soil shear strength decreased by 36.0% and 52.3%, respectively, and the soil compactness decreased 54.8% and 90.8%, respectively, and the nutrient content of the root-soil composite also decreased with the soil degradation degree. Moreover, soil pore volume was inversely related to its shear strength that decreases quickly with degradation severity. The changes in the physical and mechanical characteristics of the topsoil in degraded meadows weakened its erosion resistance, which can lead to infertile and deteriorated soil. The strategies for restoring the degraded meadows should aim at increasing vegetation roots and litter quantity in the topsoil and stabilizing soil surface structure to create an environment for pioneering vegetation such as mosses and lichens to become established first so that the degraded meadows can recover naturally. [ABSTRACT FROM AUTHOR]