Determination of Mining-Induced Changes in Hydrogeological Parameters of Overburden Aquifer in a Coalfield, Northwest China: Approaches Using the Water Level Response to Earth Tides

The determination of changes in hydrogeological properties (e.g., permeability and specific storage) of aquifers disturbed by mining activity is significant to groundwater resource and ecological environment protection in coal mine areas. However, such parameters are difficult to continuously measure in situ using conventional hydrogeological methods, and their temporal changes associated with coal mining are not well understood. The response of well water level to Earth tides provides a unique probe to determine the in situ hydrogeological parameters and their variations. In this study, the tidal responses of well water level were employed to characterize the changes in hydrogeological parameters of the overburden aquifer induced by longwall mining in a coalfield, northwest China. Based on the long-term hourly recorded water level data, two analytical models were used to determine the temporal changes of permeability and specific storage of the overburden aquifer. The results showed that the hydrogeological parameters changed with the longwall coal face advance. When the longwall coal face approached the wells, the aquifer permeability increased several to dozens of times, and the response distance ranged from 80 m to 300 m. The specific storage decreased before the coal face reached wells and recovered after the coal face passed. The results of this study indicate that the hydrogeological parameter changes induced by coal mining are related to the location of the well relative to the coal face and the stress distribution in the overburden aquifer. This study revealed the changes in permeability and specific storage associated with the mining disturbance which could have great significance for quantitative assessment of the impact of mining on overburden aquifer

Basic measurements of radiation at station Boulder, SURFRAD (2016-03)

How to efficiently design and synthesize multifunctional molecules is particularly challenging. In this presentation, we devote to constructing a kind of simple structures with composite functionalities through straightforward preparation. Starting from common commercially available materials, the titled <i>cis</i>/<i>trans-</i>tetraarylethenes can be conveniently obtained by a one-pot process under mild conditions. The different configurations were confirmed by ¹H NMR and single crystal data analysis. The <i>trans-</i>tetraarylethenes could be converted into <i>cis</i>-forms not only by photoirradiation but also by microwave irradiation, which provided us a new choice for isomeric conversion, especially in relation to light sensitivity. Results show that all the hybrid <i>cis</i>/<i>trans</i>-isomers performed switchable fluorescence and reversible photochromism in solution, PMMA film, solid powder, and single crystal. Moreover, these hybrid tetraarylethenes could be utilized as photoswitchable media to tune the behavior of aggregation-induced emission (AIE) and aggregation-caused quenching (ACQ). These versatile properties are favorable for the potential applications in fluorescent photoswitches, nondestructive readout, and logic gates. We hope that our design strategy could provide a new protocol for constructing a kind of multifunctional molecules based some simple structure and convenient synthetic procedures

Hybrid <i>cis</i>/<i>trans</i> Tetra-arylethenes with Switchable Aggregation-Induced Emission (AIE) and Reversible Photochromism in the Solution, PMMA Film, Solid Powder, and Single Crystal

How to efficiently design and synthesize multifunctional molecules is particularly challenging. In this presentation, we devote to constructing a kind of simple structures with composite functionalities through straightforward preparation. Starting from common commercially available materials, the titled <i>cis</i>/<i>trans-</i>tetraarylethenes can be conveniently obtained by a one-pot process under mild conditions. The different configurations were confirmed by ¹H NMR and single crystal data analysis. The <i>trans-</i>tetraarylethenes could be converted into <i>cis</i>-forms not only by photoirradiation but also by microwave irradiation, which provided us a new choice for isomeric conversion, especially in relation to light sensitivity. Results show that all the hybrid <i>cis</i>/<i>trans</i>-isomers performed switchable fluorescence and reversible photochromism in solution, PMMA film, solid powder, and single crystal. Moreover, these hybrid tetraarylethenes could be utilized as photoswitchable media to tune the behavior of aggregation-induced emission (AIE) and aggregation-caused quenching (ACQ). These versatile properties are favorable for the potential applications in fluorescent photoswitches, nondestructive readout, and logic gates. We hope that our design strategy could provide a new protocol for constructing a kind of multifunctional molecules based some simple structure and convenient synthetic procedures

Reliability and validity of Handwriting Test for Preschool Children (HT-PRE): A new tool to assess the handwriting ability of preschool children aged 5-6 years old in Mainland China.

BACKGROUND:Handwriting ability is related to many neuronal functions, such as visual-perceptual skills, orthographic coding, motor planning and execution, kinesthetic feedback and visual-motor coordination. To date, there is no specific assessment tool for to assess preschool children's handwriting ability in Mainland China. Our study aimed to develop a tool to assess the handwriting ability of children aged 5-6 years old in Mainland China and to analyze its reliability and validity. METHODS:The investigation comprised three phases: 1) original tool generation, 2) tool revision, 3) reliability analysis (i.e., interrater, test-retest) and validity analysis (i.e., content, criterion). RESULTS:The sample included a total of 482 children. The internal consistency (Cronbach alpha) was 0.74. The test-retest correlation coefficients ranged from 0.38 to 0.80. As expected, our data showed an improving trend in handwriting, and differences in respect to age and gender. When compared with the 'handwriting difficulty' group, each subtest score of children in the 'normal' group showed significant differences (p < 0.05). The correlation validity, compared with the visual-motor integration development test (VMI), was 0.17-0.52. CONCLUSION:The Handwriting Test for Preschool Children (HT-PRE), which is a newly developed handwriting screening tool for preschool children aged 5-6 years old in Mainland China, has displayed a very good internal consistency, acceptable test-retest reproducibility, and good criterion-based validity, and has also shown good application prospects for handwriting difficulty screening in a clinical setting

A novel aluminum-carbon nanotubes nanocomposite with doubled strength and preserved electrical conductivity

© 2021, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature. Enhancing the mechanical strength of highly conductive pure metals usually causes significant reduction in their electrical conductivity. For example, introducing phase/matrix interfaces or more grain boundaries, are common and effective methods to strengthen metals. But it simultaneously increases the electron scattering at the interface, thus reducing the electrical conductivity. In this study, we demonstrate that pure aluminum (Al)/carbon nanotubes (CNTs) nanocomposites prepared by friction stir processing have successfully broken through these limitations. The yield strength and tensile strength of Al/CNTs nanocomposites have improved by 104.7% and 51.8% compared to pure Al, while the electrical conductivity remained comparable to that of pure Al. To explore the potential mechanisms, the interface between CNTs and Al was examined and characterized by transmission electron microscopy (TEM) and Raman spectroscopy. Little interfacial reaction compounds were present and no visible physical gaps were observed at CNTs and Al interfaces. We defined it as a clean and tightly bonded interface. Although the quantity of phase interface has increased, the electrical conductivity of the nanocomposite remains approximately unchanged. We attribute the preserved electrical conductivity to the clean and tightly bonded CNTs/Al interface in the nanocomposite. [Figure not available: see fulltext.