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Milled wood lignin (MWL) was isolated from Dendrocalamus sinicus, an abundant bamboo variety in the earth, using Bjorkman method. Elucidation and quantification of the chemical structures for the isolated MWL have been facilitated by employing FT-IR and NMR techniques. The obtained results showed that the MWL consists of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, indicating it as grass type (HGS) lignin. There is no significant change in structure (i.e. cleavage at α-O-4′ and β-O-4′ linkage) was observed. NMR techniques indicated that the isolated lignin was rich in β-O-4′ aryl ether substructures and syringyl (S) units. Furthermore, the sufficient understanding of the chemical structure of the lignin benefits their effective utilization towards the production of renewable biomass and biofuels.

Background: The lignin can compete for binding cellulase enzymes with cellulose fibers and decrease the accessibility of enzymes to carbohydrates. The competitive adsorption of cellulase to lignin mainly depended on the chemical structure of lignin. The post-pretreatment can decrease the lignin content and modify the lignin structure of pretreated substrates, which reduced the lignin inhibition on enzymatic saccharification. Therefore, the post-treatment by modifying the lignin structure would attract considerable attention for weakening the cellulase–lignin interactions.Results: Three modified lignins, including sulfonated lignin (SL), oxidized lignin (OL), and carboxylated lignin (CL), were prepared from alkali lignin (AL) and their structures and physicochemical properties were characterized using FTIR, NMR, XPS analysis, zeta potential, and contact angle, respectively. Compared to AL, three modified lignin preparations exhibited the decrease in contact angle by 61–70% and phenolic hydroxyls content by 17–80%, and an obvious increase of negative charges by about 21–45%. This was mainly due to the drop of condensation degree and the incorporation of carboxylic and sulfonic acid groups into modified lignins. Langmuir adsorption isotherms showed that the affinity strength between cellulase and modified lignins significantly reduced by 54–80%. Therefore, the 72 h hydrolysis yield of Avicel with SL, OL, and CL was 48.5, 51.3, and 49.4%, respectively, which was increased 8–15.3% than that of Avicel with AL, 44.5%. In the enzymatic hydrolysis of bamboo biomass, the glucose yield at 5 d was 38.5% for AS-P. amarus, 15.4% for AO-P. amarus and 21.4% for AC-P. amarus, respectively, which were 1.4–3.5 times of alkali pretreated P. amarus.Conclusions: The post-treatment can weaken the nonproductive adsorption between lignin and cellulase proteins and improve the enzymatic saccharification efficiency. This study will provide a conceptual combination of pretreatment technologies and post-pretreatment by modifying lignin structure for reducing the cellulase–lignin interaction.

The treatment, disposal, and resource utilization of waste mud are challenges for engineering construction. This study investigates the road performance of waste mud–solidified soil and explains how solidifying materials influence the strength and deformation characteristics of waste mud. Unconfined compressive strength tests, consolidated undrained triaxial shear tests, resonant column tests, and consolidation compression tests were conducted to evaluate the solidification effect. The test results show that with an increase in cement content from 5 to 9%, the unconfined compressive strength of the waste mud–solidified soil increased by over 100%, the curing time was extended from 3 to 28 days, and the unconfined compressive strength increased by approximately 70%. However, an increase in initial water content from 40 to 60% reduced the unconfined compressive strength by 50%. With the increase of cement content from 5 to 9%, the cohesion and friction angles increased by approximately 78% and 24%, respectively. The initial shear modulus under dynamic shear increased by approximately 38% and the shear strain corresponding to a damping ratio decay to 70% of the initial shear modulus decreased by nearly 11%. The compression coefficient decreased by approximately 55%. Scanning electron microscopy and X-ray diffraction tests showed that a higher cement content led to the formation of more hydration reaction products, especially an increase in the content of AlPO 4 , which can effectively fill the pores between soil particles, enhance the bonding between soil particles, and form a skeleton with soil particles to improve compactness. Consequently, the strength of the waste mud–solidified soil increased significantly while its compressibility decreased. This study can provide data support for dynamic characteristics of waste mud solidified soil subgrade.

Collective-owned construction land (CCL) marketization is an important driving force for the rapid development of China’s rural economy and society. Recognizing the trends and logic of its institutional changes is important for better understanding the central-local interrelation and the new-round CCL reform. Throughout the process of rural land reform since China’s reform and opening up, together with the unified policy guidance from the central government, the diversity of local practices and the trend of convergence in the development process deserve attention. Based on the institutional isomorphism theory, this paper analyzes the evolution of the CCL system in Shunde, Guangdong Province, and Wujiang, Jiangsu Province, since the 1990s, empirically demonstrating the trend of convergence based on diversity and exploring the underlying influencing mechanisms. The study finds that the evolutionary practice is characterized by the trend of ephemeral convergence represented by the shared cooperative and the land reservation reform and that of coeval convergence represented by the construction land nationalization. Top-down coercive pressure, horizontal imitative learning pressure, and governance-embedded normative pressure jointly shape the evolutionary convergence. This paper argues that the diversity of local experiments should be allowed and encouraged based on local characteristics. Policy flexibility should be further considered by the central government when formulating uniform policies for local adaptability.

Background Acmella radicans (Jacquin) R.K. Jansen is a new invasive species record for Yunnan Province, China. Native to Central America, it has also been recently recorded invading other parts of Asia. To prevent this weed from becoming a serious issue, an assessment of its ecological impacts and potential distribution is needed. We predicted the potential distribution of A. radicans in China using the MaxEnt model and its ecological impacts on local plant communities and soil nutrients were explored. Results Simulated training using model parameters produced an area under curve value of 0.974, providing a high degree of confidence in model predictions. Environmental variables with the greatest predictive power were precipitation of wettest month, isothermality, topsoil TEB (total exchangeable bases), and precipitation seasonality, with a cumulative contribution of more than 72.70% and a cumulative permutation importance of more than 69.20%. The predicted potential suitable area of A. radicans in China is concentrated in the southern region. Projected areas of A. radicans ranked as high and moderately suitable comprised 5425 and 26,338 km 2 , accounting for 0.06 and 0.27% of the Chinese mainland area, respectively. Over the 5 years of monitoring, the population density of A. radicans increased while at the same time the population density and importance values of most other plant species declined markedly. Community species richness, diversity, and evenness values significantly declined. Soil organic matter, total N, total P, available N, and available P concentrations decreased significantly with increasing plant cover of A. radicans , whereas pH, total K and available K increased. Conclusion Our study was the first to show that A. radicans is predicted to expand its range in China and may profoundly affect plant communities, species diversity, and the soil environment. Early warning and monitoring of A. radicans must be pursued with greater vigilance in southern China to prevent its further spread.

The urban (suburban) railway is a fast and convenient rail transit system connecting urban and suburban areas, and a refined analysis of the diversity of public service facilities around its stations can help to promote the intensive use of land around rail stations. However, the differences in the diversity of public service facilities in the railway life circle between urban and suburban railway stations and the factors affecting them are not clear. This paper takes the Beijing Suburban Railway Line Sub-center (Line S1) as a case study, uses the Shannon-Wiener index to measure the spatial diversity characteristics of public service facilities, and utilizes a multi-scale geographically weighted regression model to explore the influencing factors. The findings indicate that: (1) Centered on the stations, all six stations show a “less-more-less” ring or half-ring to the left distribution structure of the comprehensive diversity index of public service facilities within their study areas, with an increase followed by a decrease. (2) The influence of each influencing factor on the diversity of market-featured facilities exhibits significant differences. The most substantial spatial heterogeneity is observed in the distances to the nearest subway stations and bus stops. Distances to subway and urban (suburban) railway stations exhibit different spatial distribution characteristics within urban and suburban areas on Line S1. In urban areas, the closer the distance to the subway station or the further the distance to the railway station, the greater the diversity of public service facilities. Conversely, in suburban areas, the opposite is true. The conclusions of this research provide a scientific methodology and improvement measures to facilitate the construction of railway life circles in suburban regions of megacities.

Alongside the proceeding of rural land system reform in China, it becomes more and more critical to conduct policy performance evaluations on collective-owned construction land for profitable use to reflect the achievements and deficiencies of the reform. Traditionally, land policy performance evaluation is based on the theory of “policy-performance”, which fails to explain the mechanism of transaction costs. From the perspective of spatial planning, land use and the spatial form shaped by land development management and control are a representation of land property rights, as well as an expression of land policy performance. Thus, a correct understanding of the role of spatial form in the relationship between land policy and land performance is of great significance in accurately evaluating land policy performance and further improving land policies. Focusing on the interrelation among the three factors, this article highlights and elaborates on the intermediary role of spatial form between land property rights and land policy performance and puts forward the analytical framework of “land property right–spatial form–land policy performance”. It then takes the case of Wujiang District of Suzhou in southern Jiangsu Province to prove the effectiveness of this analytical framework. The outcome of this study can serve as a supplement to “policy-performance” theory, which refines and deepens the analysis of transaction costs from the perspective of spatial planning. It may also help deepen the recognition of land policy performance through visualized presentations, providing a new perspective for performance evaluation in quantitative and qualitative ways.

Acmella radicans (Jacquin) R.K.Jansen is an annual herb native to Central America. In China, it is becoming increasingly invasive and often co-occurs with the native congener A. paniculata (Wall. ex DC.) R.K.Jansen in some habitats. In order to understand the invasion mechanism of A. radicans, we investigated the growth parameters of both the invasive A. radicans and the native congener, A. paniculata, under different light conditions (5%, 25%, 50%, 75%, and 100% of light availability) using potted plants in a glasshouse. Light level, plant species, and their interaction were significant, with plant species generally having a greater effect than light level. Acmella radicans and A. paniculata showed great phenotypic plasticity to various light intensities and had a similar trend with increased shade. The plasticity indices of all parameters of A. radicans, except for branch length and inflorescence number, were greater than those of A. paniculata under the same light intensity. The physiological parameters for A. radicans under both favorable (high light intensity) and unfavorable (low light intensity) conditions showed less inhibition than those of A. paniculata. All these responses indicated that A. radicans had greater phenotypic plasticity and higher adaptability to low light, which may contribute to its invasion success.

The study of geography is centered on the regional system of the human-land relationship, and the core of the study of the geographical system of the human-land relationship is land use change. Land use is the most direct manifestation of human activities, accompanied by changes in land cover. This is the most appropriate entry point to reveal the evolution of human-land relationships. The past 300 years have been the most intense period of social change in China and the United States. In this study, we investigated the differences and evolution of human-land relations between China and the United States from the perspective of land cover change. We found: (1) Cultivated land, forest land, and grassland areas in China and the United States have changed significantly in the past 300 years. The cultivated land area has generally increased, and the extent of forest land and grassland has declined. According to the speed of land cover change, it can be roughly divided into three different stages. The change in cultivated land in China is mainly based on the enhancement of cultivation intensity. The change in cultivated land in the United States is mainly based on expansion of cultivated land. (2) The difference in land cover change between China and the United States in the past 300 years is mainly caused by the difference in social development, interpreting human-land relationships with honest feedback and social feedback. In general, with the continuous development of land, environmental issues have become increasingly prominent, and people’s awareness of environmental protection has also increased. (3) The evolution of human-land relations in China and the United States has been influenced by natural and social factors for nearly 300 years. China is dominated by population, whereas the United States is dominated by technology. The relationship between humans and land differs between the two countries in some respects, with similarities in other areas. In both countries, this relationship can be characterized by the stages of relying on the environment, understanding the environment, transforming the environment, and protecting the environment. This evolution is in line with the law of social development, according to which human beings constantly recognize, utilize, and adapt to nature.

The impact of built environment features on tourists’ walking behaviors has received growing attention. Although many researchers have observed the effects of micro-scale factors, the impact of culture-related factors on walking behaviors has been frequently overlooked. Therefore, it is vital to synthesize those micro-scale variables to develop a more holistic picture, and incorporating a cultural perspective is an imperative for the preservation and vitality enhancement of historic streets. In our study, a micro-scale built environment (MiBE) variable system was constructed to capture the features of historic streets, and 109 visitors were tracked in Wudaoying Hutong to record their walking-stopping behaviors. The results revealed four primary components affecting walking-stopping behaviors, among which transparency was the most influential factor, followed by the transitional space between streets and buildings, contributing to 49.8% and 21.6%, respectively. Notably, the non-negligible impact of two culture-related factors, including the contrast between Chinese and Western styles and traditional Chinese features, was also revealed, contributing to 28.6% of the total observed activities. We further compared four different types of micro-scale factors of the built environment and the corresponding walking-stopping behaviors, providing both scientific and theoretical reflections for preserving and renewing historic streets.