9 research outputs found
Standard for density of population aging.
The Yangtze River Delta urban agglomeration (YRDUA) is China’s most representative region with remarkable economic development vitality. The purpose of this study is to provide valuable data analysis to actively respond to the population aging in China. We mainly focus on the spatial and temporal evolution of population aging in YRDUA from 2000 to 2020 using city-level population data. This study constructs a multi-dimensional index system to measure population aging including population aging degree, speed, and density. It finds out: (1) the elderly population rate (EPR), the elder-child ratio (ECR), and the elderly dependency ratio (EDR) in the YRDUA area are gradually increasing from 2000 to 2020. In addition, the trends of these indicators in various cities and regions are relatively consistent. All 27 cities in YRDUA entered an aging society, from the primary to the moderate aging stage from 2000 to 2010 and from the moderate to the hyper aging stage from 2010 to 2020. (2) the absolute and relative growth rate of EPR is increasing from 2000 to 2020. However, the absolute and relative growth rate of ECR is increasing from 2000 to 2010 and then decreasing from 2010 to 2020. These results indicate that the two-child policy adopted by the Chinese government plays a positive role. (3) the density level of the elderly population in the YRDUA evolved from low in 2000 to middle in 2010 and then to high in 2020. (4) There are remarkable differences in the process of population aging among three provinces and one city. The contribution of this study is mainly reflected in two aspects: firstly, it constructs a multi-dimensional index system to measure population aging; secondly, using this multi-dimensional index system, it systematically observes the spatial and temporal evolution of population aging from 2000 to 2020 in the Yangtze River Delta Urban Agglomeration.</div
Stages of population aging degree.
The Yangtze River Delta urban agglomeration (YRDUA) is China’s most representative region with remarkable economic development vitality. The purpose of this study is to provide valuable data analysis to actively respond to the population aging in China. We mainly focus on the spatial and temporal evolution of population aging in YRDUA from 2000 to 2020 using city-level population data. This study constructs a multi-dimensional index system to measure population aging including population aging degree, speed, and density. It finds out: (1) the elderly population rate (EPR), the elder-child ratio (ECR), and the elderly dependency ratio (EDR) in the YRDUA area are gradually increasing from 2000 to 2020. In addition, the trends of these indicators in various cities and regions are relatively consistent. All 27 cities in YRDUA entered an aging society, from the primary to the moderate aging stage from 2000 to 2010 and from the moderate to the hyper aging stage from 2010 to 2020. (2) the absolute and relative growth rate of EPR is increasing from 2000 to 2020. However, the absolute and relative growth rate of ECR is increasing from 2000 to 2010 and then decreasing from 2010 to 2020. These results indicate that the two-child policy adopted by the Chinese government plays a positive role. (3) the density level of the elderly population in the YRDUA evolved from low in 2000 to middle in 2010 and then to high in 2020. (4) There are remarkable differences in the process of population aging among three provinces and one city. The contribution of this study is mainly reflected in two aspects: firstly, it constructs a multi-dimensional index system to measure population aging; secondly, using this multi-dimensional index system, it systematically observes the spatial and temporal evolution of population aging from 2000 to 2020 in the Yangtze River Delta Urban Agglomeration.</div
Population aging degree of Yangtze River Delta urban agglomeration.
(Shape file source: Republished from http://www.gscloud.cn under a CC BY license, with permission from Geospatial Data Cloud, original copyright [2022]; The map was created using ArcGIS 10.2 software and the calculation data of EPR, ECR, and EDR is sourced from relevant statistical yearbook).</p
Speed of population aging in Yangtze river delta urban agglomeration (2000–2010).
Speed of population aging in Yangtze river delta urban agglomeration (2000–2010).</p
S1 Data -
The Yangtze River Delta urban agglomeration (YRDUA) is China’s most representative region with remarkable economic development vitality. The purpose of this study is to provide valuable data analysis to actively respond to the population aging in China. We mainly focus on the spatial and temporal evolution of population aging in YRDUA from 2000 to 2020 using city-level population data. This study constructs a multi-dimensional index system to measure population aging including population aging degree, speed, and density. It finds out: (1) the elderly population rate (EPR), the elder-child ratio (ECR), and the elderly dependency ratio (EDR) in the YRDUA area are gradually increasing from 2000 to 2020. In addition, the trends of these indicators in various cities and regions are relatively consistent. All 27 cities in YRDUA entered an aging society, from the primary to the moderate aging stage from 2000 to 2010 and from the moderate to the hyper aging stage from 2010 to 2020. (2) the absolute and relative growth rate of EPR is increasing from 2000 to 2020. However, the absolute and relative growth rate of ECR is increasing from 2000 to 2010 and then decreasing from 2010 to 2020. These results indicate that the two-child policy adopted by the Chinese government plays a positive role. (3) the density level of the elderly population in the YRDUA evolved from low in 2000 to middle in 2010 and then to high in 2020. (4) There are remarkable differences in the process of population aging among three provinces and one city. The contribution of this study is mainly reflected in two aspects: firstly, it constructs a multi-dimensional index system to measure population aging; secondly, using this multi-dimensional index system, it systematically observes the spatial and temporal evolution of population aging from 2000 to 2020 in the Yangtze River Delta Urban Agglomeration.</div
Population age structure.
The Yangtze River Delta urban agglomeration (YRDUA) is China’s most representative region with remarkable economic development vitality. The purpose of this study is to provide valuable data analysis to actively respond to the population aging in China. We mainly focus on the spatial and temporal evolution of population aging in YRDUA from 2000 to 2020 using city-level population data. This study constructs a multi-dimensional index system to measure population aging including population aging degree, speed, and density. It finds out: (1) the elderly population rate (EPR), the elder-child ratio (ECR), and the elderly dependency ratio (EDR) in the YRDUA area are gradually increasing from 2000 to 2020. In addition, the trends of these indicators in various cities and regions are relatively consistent. All 27 cities in YRDUA entered an aging society, from the primary to the moderate aging stage from 2000 to 2010 and from the moderate to the hyper aging stage from 2010 to 2020. (2) the absolute and relative growth rate of EPR is increasing from 2000 to 2020. However, the absolute and relative growth rate of ECR is increasing from 2000 to 2010 and then decreasing from 2010 to 2020. These results indicate that the two-child policy adopted by the Chinese government plays a positive role. (3) the density level of the elderly population in the YRDUA evolved from low in 2000 to middle in 2010 and then to high in 2020. (4) There are remarkable differences in the process of population aging among three provinces and one city. The contribution of this study is mainly reflected in two aspects: firstly, it constructs a multi-dimensional index system to measure population aging; secondly, using this multi-dimensional index system, it systematically observes the spatial and temporal evolution of population aging from 2000 to 2020 in the Yangtze River Delta Urban Agglomeration.</div
Two-Dimensional SnO Anodes with a Tunable Number of Atomic Layers for Sodium Ion Batteries
We
have systematically changed the number of atomic layers stacked
in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB)
performance. The results indicate that as the number of atomic SnO
layers in a sheet decreases, both the capacity and cycling stability
of the Na ion battery improve. The thinnest SnO nanosheet anodes (two
to six SnO monolayers) exhibited the best performance. Specifically,
an initial discharge and charge capacity of 1072 and 848 mAh g<sup>–1</sup> were observed, respectively, at 0.1 A g<sup>–1</sup>. In addition, an impressive reversible capacity of 665 mAh g<sup>–1</sup> after 100 cycles at 0.1 A g<sup>–1</sup> and
452 mAh g<sup>–1</sup> after 1000 cycles at a high current
density of 1.0 A g<sup>–1</sup> was observed, with excellent
rate performance. As the average number of atomic layers in the anode
sheets increased, the battery performance degraded significantly.
For example, for the anode sheets with 10–20 atomic layers,
only a reversible capacity of 389 mAh g<sup>–1</sup> could
be obtained after 100 cycles at 0.1 A g<sup>–1</sup>. Density
functional theory calculations coupled with experimental results were
used to elucidate the sodiation mechanism of the SnO nanosheets. This
systematic study of monolayer-dependent physical and electrochemical
properties of 2D anodes shows a promising pathway to engineering and
mitigating volume changes in 2D anode materials for sodium ion batteries.
It also demonstrates that ultrathin SnO nanosheets are promising SIB
anode materials with high specific capacity, stable cyclability, and
excellent rate performance
Investigating the Influence of Mesoporosity in Zeolite Beta on Its Catalytic Performance for the Conversion of Methanol to Hydrocarbons
Hierarchically porous zeolite Beta
(Beta-MS) synthesized by a soft-templating
method contains remarkable intracrystalline mesoporosity, which reduces
the diffusion length in zeolite channels down to several nanometers
and alters the distribution of Al among distinct crystallographic
sites. When it was used as a catalyst for the conversion of methanol
to hydrocarbons (MTH) at 330 °C, Beta-MS exhibited a 2.7-fold
larger conversion capacity, a 2.0-fold faster reaction rate, and a
remarkably longer lifetime in comparison to conventional zeolite beta
(Beta-C). The superior catalytic performance of Beta-MS is attributed
to its hierarchical structure, which offers full accessibility to
all catalytically active sites. In contrast, Beta-C was easily deactivated
because a layer of coke quickly deposited on the outer surfaces of
the catalyst crystals, impeding access to interior active sites. This
difference is clearly demonstrated by using electron microscopy combined
with electron energy loss spectroscopy to probe the distribution of
coke in the deactivated catalysts. At both low and high conversions,
ranging from 20% to 100%, Beta-MS gave higher selectivity toward higher
aliphatics (C<sub>4</sub>–C<sub>7</sub>) but lower ethene selectivity
in comparison to Beta-C. Therefore, we conclude that a hierarchical
structure decreases the residence time of methylbenzenes in zeolite
micropores, disfavoring the propagation of the aromatic-based catalytic
cycle. This conclusion is consistent with a recent report on ZSM-5
and is also strongly supported by our analysis of soluble coke species
residing in the catalysts. Moreover, we identified an oxygen-containing
compound, 4-methylbenzaldehyde, in the coke, which has not been observed
in the MTH reaction before
Functional Two-Dimensional Coordination Polymeric Layer as a Charge Barrier in Li–S Batteries
Ultrathin
two-dimensional (2D) polymeric layers are capable of
separating gases and molecules based on the reported size exclusion
mechanism. What is equally important but missing today is an exploration
of the 2D layers with charge functionality, which enables applications
using the charge exclusion principle. This work demonstrates a simple
and scalable method of synthesizing a free-standing 2D coordination
polymer Zn<sub>2</sub>(benzimidazolate)<sub>2</sub>(OH)<sub>2</sub> at the air–water interface. The hydroxyl (−OH) groups
are stoichiometrically coordinated and implement electrostatic charges
in the 2D structures, providing powerful functionality as a charge
barrier. Electrochemical performance of the Li–S battery shows
that the Zn<sub>2</sub>(benzimidazolate)<sub>2</sub>(OH)<sub>2</sub> coordination polymer layers efficiently mitigate the polysulfide
shuttling effects and largely enhance the battery capacity and cycle
performance. The synthesis of the proposed coordination polymeric
layers is simple, scalable, cost saving, and promising for practical
use in batteries