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Context The original ecosystems of mining cities are constantly being destroyed. Therefore, it becomes crucial to restore and enhance the ecological environment of mining cities and improve the carbon sink capacity of vegetation. However, there is a lack of relevant strategies to optimize. Objectives We explored the optimization strategies to enhance the ecological functionality and carbon sink of the city and verified the optimization effects. Methods We extracted the ecological spatial network of Xuzhou City, calculated the ecological functionality, carbon sink and topological indicators of the sources, and correlated the topological indicators with the carbon sink. We proposed an optimization strategy according to the results. Finally, we determine the effect of optimization by the change of robustness and carbon sink. Results We abstracted the sources as nodes and found that the ecospatial network was divided into different communities and nodes of the same community were adjacent to each other in geographic space. We also found that the three types of node carbon sinks have a significant positive correlation with the betweenness centrality of nodes. By adding ecological corridors and stepping stones, the robustness of the network and the ecological recovery ability can be improved. At the same time, the optimized carbon sink increased by 377.6 tons. Conclusions By restoring and renewing ecological space, the carbon sink of mining cities can be effectively enhanced, which provides theoretical and measure references for future ecological engineering of mining cities. In addition, it is a remote sensing application to promote urban development and sustainability.

Bioconversion of glycerol to 1,3-propanediol is a promising way to mitigate the shortage of energy. To maximize the production of 1,3-propanediol, it needs to control precisely microbial fermentation process. However, it might consume lots of human and material resources when conducting experimental tests many times. In this study, a nonlinear enzyme-catalytic dynamical system is developed to describe the bioconversion process of glycerol to 1,3-propanediol, especially continuous piecewise linear functions are used as identification parameters. The existence, uniqueness and continuity of solutions are also discussed. Then, considering the fact that the concentration of intracellular substances is difficult to measure in experiments, a new quantitative definition of biological robustness is introduced as a performance index to determine the identification parameters related to intracellular substances. Meanwhile, a two-phase optimization algorithm is constructed to solve the identification model. By comparison with the experimental data, it can be found that the present nonlinear dynamical system can describe the fermentation process very well. Finally, the present nonlinear dynamical system and the corresponding optimal identification parameters might be useful in future studies on the batch culture of glycerol to 1,3-propanediol.

Design and optimization of steam power systems (SPS) should not only optimize the economic target of the system but also ensure the safe and stable operation of the production process against compl...

The conservation of forest ecosystems and the enhancement of carbon sequestration capacity play a crucial role in maintaining ecological balance and human development. However, with excessive deforestation, the flow of energy and information within the ecosystem has changed, which in turn has led to changes in the topological properties and carbon sequestration capacity of forest ecosystems. In order to better investigate the nature and carbon sequestration capacity of forest ecological space in mainland China during 2000-2018, we constructed a time-series Chinese forest ecological spatial network based on complex network theory and graph theory, combined with the modified minimal cumulative resistance model (MCR). By combining the net primary productivity (NPP) values obtained from the Boreal Ecosystem Productivity Simulator (BEPS) model of existing scholars, we further explored the relationship between topology and carbon sequestration capacity within forest ecosystems, and proposed strategies and suggestions for optimization. The results show that forest ecological sources and ecological corridors showed an increasing trend and resistance values decreased year by year during 2000-2018, especially in the western region, indicating that ecological restoration projects in western China have achieved certain effects. However, the stability of forest ecosystems has been decreasing year by year, and the forest carbon sequestration capacity in western China is also decreasing. Through correlation analysis, we found that carbon sequestration capacity showed highly significant positive correlation with closeness centrality, harmonic closeness centrality, clustering, and eigen centrality, and carbon sequestration capacity showed highly significant negative correlation with betweeness centrality. Through Principal Components Analysis (PCA), we suggest that consolidating small patches in the northeast, reducing the number of redundant ecological corridors, adding stepping stone patches to shorten the length of ecological corridors, and increasing ecological corridors in non-northeast areas are conducive to enhancing plant carbon sequestration capacity. This study provides theoretical support and ecological engineering recommendations for China to achieve its strategic goals of carbon neutrality and carbon peaking.

We study the effects of managerial overconfidence and agency costs on cash holdings of blockchain firms, where the overconfidence is defined as a cognitive bias that a manager will underestimate volatility in an uncertain environment. We develop a real-options game model that incorporates both overconfidence and agency costs. The theoretical results show that future investment opportunities are necessary for holding cash when agency costs are within the firm. Expected returns from blockchain projects decrease with managerial overconfidence. The level of corporate cash holdings increases with overconfidence and decreases with agency costs. Using the data of Chinese listed firms from 2010 to 2019, we find that the regression results are consistent with our theoretical findings. Moreover, we find that the blockchain firms’ cash holdings are higher than their peers. Our results shed some light on the impacts of behavioral characteristics on cash holdings.

Yellow River Basin is an important ecological security barrier and an important economic belt in China. With the rapid development of China’s economy, the competition for production, living and ecological spaces(PLES) in the Yellow River Basin, is becoming more and more intensive, the ecological environment problems caused by land use change have also attracted extensive attention. In this paper, land use transition matrix, Standard deviation ellipse, spatial autocorrelation analysis, ecological contribution rate of land use transfer, etc. methods were used, to quantitatively analyze the land use conversion and spatial-temporal pattern characteristics of PLES, and the effects of those on ecological environment in the Yellow River Basin. Research indicates: Yellow River Basin is mainly dominated by production space and ecological space. In the Yellow River Basin, during the period from 1980 to 2020, the agricultural production space decreased, the woodland ecological space and living space increased, and large area of sandy land and saline-alkali land are converted into grassland ecological space; The intensity of coal exploitation has increased, and the mining center has shifted from the east to the west. In the past 40 years, the overall ecological environment quality of the Yellow River Basin has been on the rise. According to the spatial autocorrelation analysis of different land use types, the regional differences of the spatial pattern changes in the Yellow River Basin are significant, and the interactive increase-decrease relationship of different land space types has significant differences and obvious spatial heterogeneity. This paper conducts a quantitative study on the characteristics of PLES pattern changes and its ecological and environmental effects in the Yellow River Basin, providing a decision-making reference for promoting the coordinated development of PLES, which is conducive to promoting ecological security protection and high-quality development of the Yellow River Basin.

Maximising yield and minimising time are two top priorities for biotechnological industry. In this paper, we model the 1,3-PD uncoupled fed-batch fermentation process with a 10-dimensional nonlinea...

A highly selective red-emitting fluorescent and colorimetric double-channel probe incorporating a conjugated benzopyran–benzothiazole system is proposed for the detection of cyanide (CN−) in water samples. Under the presence of CN−, the probe displays red fluorescence disappearance, having an immediate (− nucleophile; 1H NMR titration and DFT calculations for this occurrence varied. Results from this investigation enable feasible and simple test strips to be produced for detecting CN− in water samples.

“Two ecological barriers and three shelters” (TEBTS), which has the effect of relieving ecological pressure, is the national ecological security pattern in China. Calculating the value of TEBTS ecosystem services, clarifying the synergy/trade-off relationships between ecosystem services, and maximizing the value of regional ecosystem services are of great significance for maintaining the security of the ecological civilization. At present, the research on ecosystem service synergy/trade-off has become the frontier field of ecology and related disciplines at home and abroad, and many research results have been obtained. However, there is still room and significance for continuing research to think about the synergy/trade-off relationship of ecosystems from the perspective of temporal and spatial heterogeneity: clarifying the spatial scope and spatial transmission characteristics of ecosystem service synergy/trade-off, exploring the trend of ecosystem service synergy/trade-off, and simulating the dynamic characteristics of natural factors affecting ecosystem services, and analyzing the characteristics of different spatial attributes that lead to the synergy/trade-off of ecosystem services. In this study, the Songhua River Basin (SRB), where the NFB is located, is used as the research area, the ecosystem services are simulated through the ecosystem assessment model, ecological unit (EU) is constructed as a research carrier, which is used to define the spatial scope of ecosystem services, and the influence of spatial characteristics and attribute characteristics on the change trend of the ecosystem service synergy/trade-off relationship is analyzed. The research found that water retention, soil conservation, and biodiversity did not change much from 2000 to 2015, and these ecosystem services have a greater value in the NFZ. The amount of carbon sequestration increased rapidly from 2010 to 2015. Crop production showed an increasing trend year by year. As the main grain production area, the Songnen Plain provides the main crop production function, which is greatly affected by humans. In the spatial characteristic, water retention, soil sequestration, and biodiversity present a very significant synergistic relationship, which is manifested in the obvious high-value aggregation characteristics in the NFZ, and crop production and the other four types of ecosystem services are in a trade-off relationship. At the time scale, the four types of ecosystem services, including water retention, soil conservation, biodiversity, and carbon sequestration, are synergistic, and crop production and water retention are synergistic. The vegetation types exhibiting a synergy/trade-off relationship are mainly broad-leaved forests, and the soil types are mainly luvisols and phaeozems. These EUs are mainly distributed in the NFZ and have spatial topological characteristics: the area and circumference of these EUs are smaller, the radius of gyration is also significantly smaller than that of other EUs, and the shape is more regular. By focusing on the spatial aggregation characteristics and changing trends of the ecosystem service synergy/trade-off and clarifying the influencing factors of the ecosystem service synergy/trade-off, the ecosystem services can be integrated, and the ecosystem can be optimized. Thus, the value of regional ecosystem services can be maximized, and a certain data foundation and theoretical support can be provided for major projects, such as ecological restoration and ecological environment governance, which is of great significance for improving the pattern of ecological security.

The water cycle in the key agricultural and pastoral zones (KAPZs) is an important factor for maintaining the stability of the ecosystem. Groundwater collection and lateral seepage are indispensable parts of the water cycle, and it is difficult to monitor the groundwater situation in each area. The strength of the alternate circulation of groundwater is directly related to the utilization value and development prospects of groundwater, therefore, creating an effective method for the detection of groundwater burial depth has become an issue of increasing concern. In this paper, we attempt to create a method for the detection of groundwater burial depth that combines cokriging interpolation, spatial autocorrelation, geographically weighted regression, and other methods to construct a quantitative relationship between different land cover types and groundwater depth. By calculating the band index of the land cover type, the groundwater depthinformation of the unknown area can be obtained more accurately. Through collaborative kriging interpolation, normalized difference vegetation index (NDVI), precipitation, and hydrogeological conditions were used as covariates. The groundwater burial depth of Wengniute Banner in 2005, 2009, 2013, and 2017 was the response variable, and the groundwater burial depth in the study area was calculated. The groundwater burial depth data after the cokriging interpolation was used to transform the raster data into vector data in space using the improved hydrological response unit (HRU) model to make it more suitable for the actual groundwater confluence. Subsequently, 551 minimum response units (MHRUs) were obtained by division, and the spatial autocorrelation analysis was performed accordingly. The groundwater burial depth in the study area is spatially distinct from east to west, and the groundwater level shows a trend of being high in the west and low in the east, gradually increasing due to precipitation and rivers. The average change of groundwater depth in the time series is not significant, but it does gradually show a trend of accumulation. According to the aggregation characteristics of spatial autocorrelation analysis, a geographically weighted regression model of groundwater depth and NDVI, normalized difference drought index (NDDI), and net relatedness index (NRI) was established. The NDVI representing the forest land and the Adjusted R2 of the groundwater depth is 0.67. The NRI representing the cultivated land and the Adjusted R2 of the groundwater depth is 0.8675. The NDDI representing the bare land and the Adjusted R2 of the groundwater depth is 0.7875. It shows that the band index representing the ground type has a good fitting effect with the groundwater burial depth.

This paper investigates the impacts of horizontal mergers on a dual-channel supply chain given the rapid development of e-commerce. Three types of horizontal mergers are considered in a dual-channel supply chain consisting of three firm types: suppliers, single-channel retailer, and dual-channel retailer. A comparison with a benchmark pre-merger scenario underscores the impacts of each horizontal merger on firms in the dual-channel supply chain. First, where horizontal mergers occur (i.e., at upstream or downstream tier) has an impact on firms in the dual-channel supply chain. Second, synergy costs trigger the domination of the synergy effect. Third, the degree of consumer preference for channels affects the trigger due to which the synergy effect outweighs the competitive effect. Although dual channels prevail in supply chain management, few studies pay attention to horizontal mergers in this context. Unlike literature on horizontal mergers in single-channel supply chains, we suggest that the impacts of horizontal mergers in dual-channel supply chains have unique features, and channel preference plays an important role in such impacts.

In this paper, we propose a scheme of wireless multimedia network coded broadcast retransmission, based on Device-to-Device (D2D) communications, in which there are network coding conflicts and transmission conflicts between multiple terminal devices. For this reason, a novel instantly decodable network coding (IDNC) graph is constructed, where all the feasible coding and non-transmission collision cases are shown in the graph. Based on the constructed IDNC graph, we design the optimal broadcast strategy for batch transmission and sliding window transmission, and propose a heuristic maximum weight network coding selection algorithm (MWSA-NC) to reduce the complexity of the optimal search algorithm. The simulation results show that compared to the traditional scheme, the proposed algorithm can greatly improve the throughput of the system, reduce decoding latency and reduce video stream distortion.

We consider an optimal control problem for a class of nonlinear switched systems with mixed constraints, in which both the mode sequence of active subsystems and the number of switches are not prescribed. By introducing convex combinations of the subsystems and the constraints, an embedded system is formulated. The relationships between the trajectories of the switched system and the corresponding embedded system are discussed. Necessary optimality conditions and the existence condition of optimal solutions are derived. A constructive parallel algorithm is proposed for solving optimal or suboptimal solutions of the considered problem. In order to avoid the case that the switching times may be lost, the time-scaling transformation is applied to transform the variable switching times to pre-fixed switching times. Finally, an optimal control of fed-batch fermentation is solved by applying the proposed algorithm, and the numerical results show that the proposed algorithm is effective.

In the actual microbial fermentation process, excessive or insufficient substrate can produce inhibitory effects on cells growth. The artificial substrate feeding rules by past experiences have great blindness to keep substrate concentration in a given appropriate range. This paper considers that alkali feed depends on pH value of the solution and glycerol feed depends on glycerol concentration of the solution in the uncoupled microbial fed-batch fermentation process, and establishes a state-dependent switched system in which the flow rates of glycerol and alkali, the number of mode switches, the mode sequence and the switching times are prior unknown. To maximize the yield of target product 1,3-Propanediol (1,3-PD), we formulate a switching optimal control problem with the flow rates of glycerol and alkali, the number of mode switches, the mode sequence and the switching times as decision variables, which is a mixed-integer dynamic programming problem. For solving the mixed-integer dynamic programming problem, the control parametrization technique, the time scaling transformation and the embedded system technology are used to obtain an approximate parameter optimization problem. By using a parallel optimization algorithm, we obtain the optimal control strategies. Under the obtained optimal control strategies, the 1,3-PD yield at the terminal time is increased significantly compared with the previous results.

A scientific and reasonable ecological compensation scheme (ECS) is an important guarantee for promoting coordinated and equitable development between regions. The existing ECSs usually ignore the premise that the ECS can only be accepted by the stakeholders if there are a clear scope and benefit to the ecosystem services (ES). An ecological compensation scheme should be based on the transmission principle of ES so that a scientific and reasonable scheme can be proposed and accepted by the stakeholders. Based on the theory of ecosystem service flow, this paper analyzed the provision‒benefit mechanism of sand-stabilization ecosystem service (SSS) and selected Ordos City, Inner Mongolia, which is located in Northwest China, as the study area. A revised wind erosion equation (RWEQ) model was used to estimate the sand-stabilization amount of Ordos’s ecosystem in 2015, and a hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model was used to simulate the path of sand-stabilization ecosystem service flow (SSSF). Then, the benefit areas and levels of SSS were identified, and the spatial distribution of land cover, population, and gross domestic product (GDP) in the ecosystem services beneficiary area (SBA) was evaluated. Based on the identified benefit areas and benefit levels, and combined with the investment and income in the ecological construction of the Ordos, a cross‒regional differentiated ECS was proposed. The results show that the Ordos’s ecosystem played a huge role in sand-stabilization, which have brought huge ecological and economic benefits. In 2015, the sand-stabilization amount of Ordos’s ecosystem was about 7.20 × 10 8 tons. The area of SBA is 1.66 × 10 6 K m 2 , accounting for 17.21% of China’s total area, this mainly involves 16 provinces and cities, including Beijing, Tianjin, Hebei, etc. The amount of dust‒fall (ADF) in the beneficiary area was reduced by 28,738.67 × 10 4 tons, and investment of 4,318.51 × 10 8 RMB (Renminbi) in dust removal would be avoided. For the ECS, based on the principle of “equity, beneficiary compensation, more benefit and more compensation”, Ordos shall take care of the ecological compensation fee (ECF) of about 36.28% of the total. In 16 provinces and cities, Inner Mongolia costs 66,121.03 × 10 4 RMB, which is the most. The fees are payable by other SBAs decrease with distance. Hubei Province (Suizhou) pays the least in ecological compensation, at 7.5 × 10 4 RMB. Based on the theory of ecosystem service flow, this paper proposes a research framework of differentiated ECS of SSS, which can provide an accurate scientific basis for determining the SBA and cross-regional ECS of SSS in the future.

Many areas on the earth are facing the threat of ecological degradation, and unreasonable economic development has further exacerbated environmental problems. Constructing ecological security patterns based on an ecological network is such an integrated approach to protecting regional ecological sustainability. This paper selected Denko County of Bayannaoer City, Inner Mongolia, which is located in the desert oasis area, as the study area. Ecological sources were identified through ecosystem importance assessment, and interaction force theory was used to model ecosystem processes in heterogeneous landscapes via comparing the minimum cumulative ecological resistance and the maximum ecological gravity between ecological sources, and thus to identify ecological corridors and to constructing forest-grass ecological network (FG eco-network) of the study area. This paper also set 11 development scenarios to study the impact of different development strategies on the FG ecological network. Moreover, the complex network theory was used to analyze the topology and statistical characteristics of the FG eco-network in 11 development scenarios. The results show that the ecological network in the study area has been gradually destroyed with the increase of the proportion of economic development in the development scenario; the connection between some ecological patches has changed and the connectivity and coreness, PageRank, etc. have gradually decreased. The study found that the network density increases slightly in the (0.9, 0.1) mode, while it gradually decreases in other scenarios with the increase of the proportion of economic development. Moreover, in the (0.9, 0.1) mode, although the destruction occurred at the edge of the desert, the FG eco-network within the sample circle expanded. This represents that economic development does not necessarily lead to the deterioration of the ecological environment in this area. Under the existing natural conditions, the study area still has room for economic development, but space is limited. Based on the interaction force theory, this study provides a new approach to identifying the ecological network. Also, the development scenarios set up in this study can provide a reference for sustainable development.

A new kind of mono-oxazoline ligands which combined diaryl methyl units and chiral oxazoline units together using pyridine as linker was prepared. Their applications in enantioselective electrophilic fluorination of β -ketoesters by NFSI were investigated, and the corresponding products were obtained in excellent yield (up to 90%) and good enantioselectivity (78%) in CH 2 Cl 2 at −60 °C.

The reaction mechanisms of palladium-catalyzed divergent reactions of 1,6-enyne carbonates have been investigated using DFT calculations at the B3LYP/6-31G(d,p) (LanL2DZ for Pd) level. Solvent effects on these reactions have been considered by the polarizable continuum model (PCM) for the solvent (DMF). The formation of vinylidenepyridines and vinylidenepyrrolidines were generated through 5-exo-dig cyclization or 6-endo-dig cyclization. Our calculation results suggested the following: (i) The first step of the whole cycle is the rate-determining step, which causes allenic palladium intermediate through two plausible pathways. This intermediate provides the corresponding products and releases the palladium catalyst by a subsequent hydrogen transfer and elimination process. (ii) For the catalyst CH 3OPdH, the reaction could occur through two possible pathways, but 5-exo-dig cyclization is favoured over 6-endo-dig cyclization. However, when the hydrogen atom is substituted with a phenyl group, the energy barriers for 5-exo-dig cyclization or 6-endo-dig cyclization become relatively high, 18.0–28.5 kcal/mol. The computational results provide good explanation for the experimental observations.

We are concerned with designing an optimal binary determine linear network coding (B-DLNC) strategy with the aim of reducing the number of transmissions and the average packets decoding delay for wireless broadcasting scenarios. In this paper, we first propose the concept of the B-DLNC that no longer limits the encoding packets to be immediately decoded by the receivers and allows the receivers to cache the correctly received undecodable retransmission packets waiting for future decoding opportunities. Next, we use channel coding theory (generation matrix and decoding matrix) to analyze the performance of B-DLNC strategy. In addition, we formulate the average packets decoding delay minimization problem as a max-weight search problem and propose a heuristic algorithm (IMWSA) to improve search efficiency. The simulation results show that compared with the traditional strategies, the proposed strategy can obviously reduce the number of transmissions and average packets decoding delay.

PHA granule binding protein phasin (PhaP) has a high affinity for hydrophobic materials and can bind to hydrophobic polymers via strong hydrophobic interaction. In this study, an EGFR-targeting peptide (ETP) was fused with PhaP and the fusion protein ETP-PhaP was produced in recombinant Escherichia coli BL21 (DE3) (pPI-ETP-P) and then purified by Ni affinity purification. The tumor targeting PHBHHx nanoparticles were developed based on PhaP mediated ETP immobilization and the cellular uptake of the ETP-PhaP modified PHBHHx NPs and none modified PHBHHx NPs by cervical cancer cell lines SiHa (EGFR over expressed) and CaSKi (EGFR low expressed) were analyzed. The purified ETP-PhaP could be adsorbed onto the hydrophobic surface of PHBHHx NPs. The ETP-PhaP modified PHBHHx NPs could target to EGFR over expressed cervical cancer cells SiHa more efficiently than to the EGFR low expressed CaSKi cells. These results demonstrated the advantage in effectiveness and convenience of PhaP mediated ETP adsorption on PHBHHx nanoparticles, providing a novel strategy for hydrophobic nanocarrier surface modification.聚羟基脂肪酸 (PHA) 颗粒表面结合蛋白PhaP 具有与疏水性高分子材料表面紧密结合的能力，本研究将EGFR 靶向多肽 (ETP) 与PhaP 进行融合表达，构建了ETP-PhaP 融合蛋白表达的重组工程菌Escherichia coli BL21(DE3)(pPI-ETP-P)。经对工程菌株的诱导表达及ETP-PhaP 融合蛋白的纯化后，通过PhaP 蛋白介导能够有效地将ETP-PhaP 融合蛋白修饰于3-羟基丁酸-3-羟基己酸共聚酯 (PHBHHx) 纳米微球表面，构建成为具有EGFR 靶向作用的药物递送载体。分别检测宫颈癌细胞系SiHa(EGFR 高表达) 和CaSKi(EGFR 低表达) 对ETP-PhaP 修饰的PHBHHx 纳米药物载体和未经修饰的纳米药物载体的吞噬情况。结果显示，纯化的ETP-PhaP融合蛋白能够很好地吸附于PHBHHx 颗粒的表面，经ETP-PhaP 融合蛋白修饰的PHBHHx 纳米药物载体对EGFR 高表达的宫颈癌SiHa 细胞的靶向效果强于EGFR 低表达的CaSKi 细胞系。这一结果表明了PhaP 介导的PHBHHx 纳米微球表面EGFR 靶向多肽修饰具有简便、高效的优势，为疏水性纳米药物载体表面功能多肽修饰提供了一种新策略。.

A theoretical investigation of the [3+2] cycloaddition reaction of the NHC-boryl azide with alkynes and nitriles has been presented by using the DFT (B3LYP) method. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum model (PCM) for the solvent (C6H6). The title reaction could produce two different five-membered products (1,4-regioisomer and 1,5-regioisomer). The reaction pathway involves a one-step mechanism through a [3+2] addition where two nitrogen atoms of the N-heterocyclic carbene boryl azide adds to the C≡A (A=C or N) bond to form two new C–N or N–N bonds. For alkynes, the reactions can take place more easily to give 1,4-regioisomer product, while the reactions proceed for nitriles along the 1,5-regioisomer pathway. The reaction systems have high chemical reactivity with low barriers and could be favored. The calculations indicated that the cycloaddition reaction of alkynes and nitriles has the better regioselectivity. Our computational results are good consistent with the experimental observations of Merling and co-workers for [3+2]-dipolar cycloaddition reaction of N-heterocyclic carbene boryl azide.