ABSTRACT
Building a scientific and reasonable ecological network is the key for optimizing the pattern of territorial development and protection, and is of great significance for ensuring regional ecological security and promoting the virtuous cycle of ecosystems. In previous studies, nodal attack method (destruction of ecological source area) was often used in the "robustness" evaluation of ecological networks. Actually, the ecological corridor is more fragile than the source area, and thus the nodal attack method is not reasonable. In this study, taking Jiuquan City as the research area, based on the circuit model to construct the ecological network, we carried out the topology optimization of ecological network by using three strategies (random edge increase, node degree and priority edge increase with low node intermedium number) in complex network theory. We compared and analyzed the "robustness" of ecological network before and after optimization by constructing edge attack strategy, and selected the best network optimization strategy. The results showed that 65 ecological source areas were identified in Jiuquan City, with a total area of 20275.15 km2, and that grassland accounted for 89.5% of the source area. We identified 179 ecological corridors with a total length of 6387.16 km, 158 ecological barrier points with a total area of 1385.5 km2. The unused land accounted for 92.2% of the total barrier points area. We identified 63 ecological pinch points, mainly concentrated in the source edge and corridor intersection. Among them, the spatial distribution of 11 barrier points and pinch points was consistent, which was the key area to be repaired in ecological network optimization. The three optimization strategies had significantly improved the stability of ecological network in Jiuquan City. The relative size of the maximum connected subgraph and the edge connected rate of the ecological network of the optimization strategy of adding edges according to degree were all the most stable under random attack mode and deliberate attack mode, which was the best optimization scheme for ecological network in Jiuquan City.
Subject(s)
Conservation of Natural Resources , Ecosystem , Cities , China , EcologyABSTRACT
Based on the background of carbon peaking and carbon neutrality goal strategies, it is important to explore the impact of land use change on carbon storage and the drivers of spatial variation in carbon storage in the Northwest Arid Zone, which is vital to improve the carbon sink increment of the regional ecosystem and promote the regional carbon breakeven. The arid region of northwest China is an extremely fragile natural ecology, and with the rapid advancement of new urbanization, the rate of land use change has accelerated significantly, which has a certain impact on the carbon storage and fixation capacity of ecosystems. The PLUS-InVEST model was used to simulate the spatial and temporal evolution characteristics of carbon storage under natural development, intensive development, water resource constraint, and ecological protection scenarios in Jiuquan City in 2035, and the parameter optimal geographic detector model was used to analyze the spatial divergence drivers of carbon storage. The results showed that:â the area of cultivated land, watershed, and construction land in Jiuquan City showed a significant increasing trend from 1990 to 2020, whereas the area of the remaining land use types showed a decreasing trend. â¡ The carbon storage in Jiuquan City increased from 7 722 808.1 t to 7 784 371 t from 1990 to 2020, and the conversion of grassland into unused land was the main cause of the loss of regional carbon storage, accounting for 85% of the total loss. ⢠All four development scenarios in 2035 showed an increasing trend of carbon storage, among which the ecological protection scenario had the most significant increase, with an increment of 76 989.29 t. ⣠The degree of land use, population density, GDP density, and NDVI were the main driving factors of the spatial variation in carbon storage in Jiuquan City, among which the degree of land use had the strongest explanatory power (q value of 0.849), and the interaction of natural and anthropogenic factors enhanced the explanatory power of each factor on the spatial variation in carbon storage. The results of the study can provide a scientific basis and decision basis for the integrated ecosystem management and territorial space optimization in Jiuquan City.
ABSTRACT
Based on the PSR model, we built an evaluation system for resource and environment carrying capacity. We used the entropy weight method, the comprehensive index model and the spatial analysis function of GIS to explore the spatial-temporal dynamic of the resource and environment carrying capacity of the Lanzhou-Xining urban agglomeration, and used the obstacle degree model to identify the obstacle factors. The results showed that resource and environment carrying capacity of the Lanzhou-Xining urban agglomeration from 2005 to 2018 showed a fluctuating upward trend, which was generally at good condition. The coefficient of variation of resource and environment carrying capacity had a fluctuating upward trend, while regional differences were gradually expanding. Spatially, resource and environment carrying capacity presented a "dual-core" structure centered on the main urban areas of Lanzhou and Xining. The high-level areas were mainly concentrated in the Hehuang Valley with Lanzhou and Xining as the center and some surrounding counties, while the low-level areas were distributed in the central and southern regions of the urban agglomeration. Among them, there were spatiotemporal variations of the subsystem index. The pressure index showed a fluctuating and decreasing trend, and spatially showed a decreasing distribution characteristic from Lanzhou and Xining urban areas to the peripheral areas. The state index showed a fluctuating upward trend, and spatially showed the evolution characteristics of high in the east and west wings and low in the middle. The response index showed an upward trend, and spatially showed distribution patterns high in the east and middle, and low in the west and outside. The urbanization rate, per capita industrial wastewater discharge, domestic waste harmless treatment rate, water consumption index, and the proportion of environmental protection investment in GDP are the main obstacles restricting the improvement of resource and environment carrying capacity of Lanhzhou-Xining urban agglomeration.
Subject(s)
Conservation of Natural Resources , Rivers , China , Cities , Economic Development , Urbanization , WastewaterABSTRACT
Using the four periods of land use data and socio-economic statistics of Lanzhou City in 1995, 2005, 2015 and 2018, we examined the evolution characteristics and driving forces of urban land use in Lanzhou, with expansion intensity index, Logistic regression, and principal component analysis method. Based on the multi-agent model, the expansion of urban land use in Lanzhou under multiple scenarios in 2025 was simulated using Netlogo software. The results showed that the intensity and scale of urban land expansion in Lanzhou City from 1995 to 2018 showed an increasing trend, with a total of 307 km2 of cultivated land and water area. The expansion of urban land in Lanzhou City was significantly related to regional GDP, social fixed asset investment, population density, population, policy, and terrain. The multi-agent model on the Netlogo software could simulate the expansion trend of urban land in Lanzhou, which provided a reliable simulation method for the expansion of valley-type cities. From 2020 to 2025, urban land use under the comprehensive development scenario, natural expansion development scenario, ecological and farmland protection development scenario all showed an increasing trend. The scale of expansion would range between 42.6-134.3 km2. The expansion mode would mainly be infilled expansion. Our results could provide decision support for the land space planning and ecological environment layout optimization for Lanzhou City.
Subject(s)
Conservation of Natural Resources , Urbanization , China , Cities , Computer SimulationABSTRACT
Zhangye serves as a good case for studying ecological services because of its fragile ecological environment and its ecological importance. Using land use data from 1987, 2000 and 2016 as well as the modified ecosystem service value (ESV) equivalent, the ESV was estimated and its spatial and temporal changes and gradient differentiation characteristics were analyzed by dividing the studied region into a grid of 3 km×3 km in size. The results showed that from 1987 to 2016, the ESV in Zhangye increased by 564 million Yuan, with the mountainous areas in the south and the desert areas in the north being stable. The ESV of central oasis areas with concentrated human acti-vities significantly changed. Forests contributed to most of the ESVs. Water regulation value was the strongest among all the individual ESVs. The ESV showed strong spatial dependence. Based on the spatial pattern of the two aggregated poles, it shaped three "flower arrangement" clusters, including Ganzhou District, Yanzhi Mountain, and Jingtie Mountain. The ESV distribution showed a topographic differentiation as the value decreased from the Qilian Mountains to the plain oasis, and further to the desert areas. The linear correlation of the terrain and the ESV was negative. As the increasing elevation gradient, the ESV showed a "decreased-increased-decreased" trend, while and it had a "decreased-stable-decreased" in the increasing slope gradient. Overall, the ESV presented two turning zones on the terrain gradient, indicating that both the piedmont zone and the oasis desert transition zone acted as transition zones of the ESV. Areas with the strongest ESV were distributed in the low slope and low terrain relief zones, and the development of oases in flat terrain areas were strongly constrained by water resources.
Subject(s)
Conservation of Natural Resources , Ecosystem , China , Forests , Humans , WaterABSTRACT
The Shiyang River Basin is an important ecological area of the Eastern Hexi Corridor, and is one of the most prominent areas of water conflict and ecological environment problems. An assessment of ecosystem quality in the Shiyang River Basin can provide a reference for ecological protection in arid inland basin. Based on the concept of ecosystem quality and the statistical yearbook, remotely sensed and land cover data, an evaluation index was established with consideration of three aspects of ecosystem (i.e., productivity, stability and bearing capacity). Kruskal-Wallis (Φ2) test and entropy method were applied to determine the weights of evaluation index. With the assistance of RS, GIS and SPSS software, a comprehensive evaluation and change analysis of ecosystem quality and corresponding index were conducted for various ecosystem types in the Shiyang River Basin in 2000, 2005, 2010 and 2015. Results showed that the average ecosystem quality of the Shiyang River Basin was 57.76, and presented an obvious decrease with a magnitude of 0.72 per year du-ring 2000-2015. The spatial pattern of ecosystem quality was that the upstream was better than the midstream, and the midstream was superior to the downstream. The mean values of production capacity, stability and carrying capacity of ecosystem were 67.52, 45.37, and 58.53, respectively. Production capacity and stability had increased slightly, while carrying capacity gradually decreased. Considering various ecosystem types, the highest quality was detected for forest ecosystem with average annual value of 78.12, and this ecosystem presented the lowest decreasing magnitude of 0.28 per year; for grassland, farmland and urban ecosystems, the average annual value was 62.45, 58.76 and 50.29, respectively; the quality of wetland ecosystem was the lowest, and suffered the largest decline with an average rate of 0.98 per year.
Subject(s)
Conservation of Natural Resources , Ecosystem , Geographic Information Systems , China , Environmental Monitoring , RiversABSTRACT
The relationship between economic development and environment and the evolution characteristics of spatial pattern in Hexi Corridor of Northwest China were analyzed based on Landsat images in 1985, 1995, 2000 and 2011 with twenty counties in Hexi Corridor chosen as the basic research units. The ecological economic harmony during 1985-2011 was estimated according to ESV (ecosystem services value) and EEH (ecological and economic harmony) index with the ecosystem services value estimation methods. The results showed that the land type of the study area dramatically changed during the study period, the grassland decreased badly, and the construction land and cultivated land increased quickly. The ESV showed an overall downward trend, especially in the Shiyang River basin and the middle of Heihe River. The ESV in the Shule River basin in this period. After 2000, the economic growth speeded up visibly in the study area. The economic development concentrated in the resource-based cities and regional central cities, and declined from the center of corridor to the both sides. The ecological-economic relation in Hexi Corridor experienced a transformation of "preliminary deterioration--further deterioration--low grade coordination". The EEH had large changes in the Shiyang River basin and the middle of Heihe River, which experienced a transformation of "conflict--more conflicts--less conflicts", however, there was little change in Shule River basin. The development mode and the comprehensive reclamation of Shiyang River basin and Heihe River basin had a significant influence on the regional ecological and economic harmony.
Subject(s)
Conservation of Natural Resources , Economic Development , Environment , China , Ecology , RiversABSTRACT
AIM: To prepare RGD4CßL fusion protein using prokaryotic expression system and evaluate the biological activity of the RGD4CßL. METHODS: RGD4CßL gene was cloned into pColdII to contruct ß-Lactamase prokaryotic expression vector. After transformation, the recombinant vector was induced to express recombinant protein RGD4CßL by IPTG in E.coli BL(DE3). The recombinant protein was purified by Ni-NTA resin under denaturing condition and then dialyzed to renature. The tumor cell targeting ability of the recombinant protein was analyzed by flow cytometric analysis. RESULTS: After cleavage and purification, ß-Lactamase moiety showed the expected size of 42 000 on Tricine-SDS-PAGE, and was further confirmed by Western blotting. Based on flow cytometric analysis, the purified protein specially targeted breast cancer cell line MCF-7. CONCLUSION: This research successfully estiblished a method for prokaryotic expression and purification of ß-lactamase. These results suggest the potential use of the protein as an agent for ADEPT.
Subject(s)
Prokaryotic Cells/physiology , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/pharmacology , beta-Lactamases/genetics , beta-Lactamases/pharmacology , Animals , Breast Neoplasms/drug therapy , Cell Line, Tumor , Cloning, Molecular/methods , Escherichia coli/genetics , Escherichia coli/metabolism , Female , Flow Cytometry/methods , Gene Expression , Genetic Vectors , Plasmids/genetics , Prokaryotic Cells/chemistry , Prokaryotic Cells/metabolism , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/isolation & purification , Sequence Analysis, DNA/methods , beta-Lactamases/biosynthesis , beta-Lactamases/isolation & purificationABSTRACT
In the title compound {systematic name: N-[(4R,5R)-3,11-dioxo-10-oxa-6-thia-2-aza-tricyclo-[6.3.0.0(2,5)]undec-1(8)-en-4-yl]-2-phenyl-acetamide}, C(16)H(14)N(2)O(4)S, the four- and five-membered rings adopt planar conformations (with r.m.s. deviations of 0.0349 and 0.0108â Å respectively) while the six-membered ring adopts a half-chair, or envelope-like, conformation with the S atom in the flap position. In the crystal, mol-ecules are linked by N-Hâ¯O hydrogen bonds.
ABSTRACT
Antibody-directed enzyme prodrug therapy (ADEPT) delivers chemotherapeutic agents at high concentration to tumor tissues while minimizing systemic drug exposure. ß-Lactamases are particularly useful enzymes for ADEPT systems due to their unique substrate specificity, which allows the activation of a variety of lactam-based prodrugs with minimal interference from mammalian enzymes. This study used integrin α(v)ß(3) as a target for tumor-specific delivery of ß-Lactamase. ß-Lactamase was fused with ACDCRGDCFCG peptide (RGD4C) by recombinant DNA technology. Likewise, this study cloned a fused cDNA and successfully expressed active recombinant protein in E. coli purified with Ni-NTA resin. After purification, ß-Lactamase moiety showed the expected size of 42 kDa on Tricine-SDS-PAGE, and was further confirmed by Western blotting. Based on flow cytometric analysis, the purified protein was found to be active for specificity in breast cancer cell line, MCF-7, which supports the utility of the protein as an agent for ADEPT.
