Spatiotemporal Urban Land Use Changes in the Changzhutan Region of Hunan Province in China

The Changzhutan region in the north-central part of Hunan Province in China has experienced a rapid urbanization in the past few decades that has led to substantial changes in its environment. In 2007, the National Development and Reform Commission of China designated the metropolitan district of Changsha City, Zhuzhou City, and Xiangtan City of this region as the fourth National Demonstration Area where economic development should be implemented in harmony with resource-saving and environment-friendly land use practices. The research, focus of this article will be on quantifying the spatial pattern of urban land use change which not only can provide an assessments and predictions of future environmental effects, but also will serve as a scientific basis for the development of urban sustainability. This paper integrates historical Landsat TM imagery, geographical information system (GIS) and socioeconomic data to determine the spatiotemporal urban land use dynamics and conversion of land use in response to the rapid urbanization of a select group of cities in China from 1990 to 2007. The approach is based on Principle Component Analysis to determine and model the relationship between the socioeconomic factors and land use/cover change (LUCC) for identifying the driving forces. The results indicate that land cover of the Changzhutan region mainly consists of forestland and cropland which accounted for about 93% of the total land area. During the 1990-2007 study period, the urban areas and water bodies increased by 46,297 ha and 775 ha, respectively, while forestland, cropland, and grassland decreased appreciably by 22,580 ha, 21,808 ha, and 5618 ha, respectively. Moreover, the urban land area during the 2000-2007 period increased by five times as much as that during the 1990-2000 period. The land use dynamic degree of Changsha City is the largest one followed by that for Xiangtan and Zhuzhou Cities. During this study period, the land use comprehensive intensity index increased and followed the sequence Xiangtan > Changsha > Zhuzhou. The changes were attributed to economic development, population growth, infrastructure improvements and construction, and land use policies. To address the negative or eco-environmental deleterious effects of these changes, landscape ecology plan, population growth control, and the development of an ecological friendly agriculture were suggested.

In situ polymerization of water-induced 1,3-phenylene diisocyanate for enhanced efficiency and stability of inverted perovskite solar cells

In the realm of photovoltaics,organometallic hybridized perovskite solar cells(PSCs)stand out as promising contenders for achieving high-efficiency photoelectric conversion,owing to their remarkable performance attributes.Nevertheless,defects within the perovskite layer,especially at the perovskite grain boundaries and surface,have a substantial impact on both the overall photoelectric performance and long-term operational stability of PSCs.To mitigate this challenge,we propose a method for water-induced condensation polymerization of small molecules involving the incorporation of 1,3-phenylene diisocyanate(1,3-PDI)into the perovskite film using an antisolvent technique.Subsequent to this step,the introduction of water triggers the polymerization of[P(1,3-PDI)],thereby facilitating the in situ passivation of uncoordinated lead defects inherent in the perovskite film.This passivation process demonstrates a notable enhancement in both the efficiency and stability of PSCs.This approach has led to the attainment of a noteworthy power conversion efficiency(PCE)of 24.66% in inverted PSCs.Furthermore,based on the P(1,3-PDI)modification,these devices maintain 90.15% of their initial efficiency after 5000 h of storage under ambient conditions of 25℃ and 50±5% relative humidity.Additionally,even after maximum power point tracking for 1000 h,the PSCs modified with P(1,3-PDI)sustain 82.05% of the initial PCE.Small molecules can rationally manipulate water and turn harm into benefit,providing new directions and methods for improving the efficiency and stability of PSCs.