Monitoring and analysis of blasting vibration in tunnel excavation of nuclear power plant

Vibration monitoring of blasting excavation of drainage tunnel in Lufeng Nuclear Power Plant is carried out and the data of blasting vibration is analyzed in this paper. The results show that: (1) The vertical vibration velocity of the rock mass is greater than the horizontal radial and horizontal tangential vibration velocity (2) The blasting vibration velocity of rock mass decreases with distance, which is affected by rock structure and explosive quantity. The monitoring research in this paper has guiding significance for vibration prediction and control in tunnel blasting excavation

Managing Excess Lead Iodide with Functionalized Oxo‐Graphene Nanosheets for Stable Perovskite Solar Cells

Stability issues could prevent lead halide perovskite solar cells (PSCs) from commercialization despite it having a comparable power conversion efficiency (PCE) to silicon solar cells. Overcoming drawbacks affecting their long-term stability is gaining incremental importance. Excess lead iodide (PbI2) causes perovskite degradation, although it aids in crystal growth and defect passivation. Herein, we synthesized functionalized oxo-graphene nanosheets (Dec-oxoG NSs) to effectively manage the excess PbI2. Dec-oxoG NSs provide anchoring sites to bind the excess PbI2 and passivate perovskite grain boundaries, thereby reducing charge recombination loss and significantly boosting the extraction of free electrons. The inclusion of Dec-oxoG NSs leads to a PCE of 23.7 % in inverted (p-i-n) PSCs. The devices retain 93.8 % of their initial efficiency after 1,000 hours of tracking at maximum power points under continuous one-sun illumination and exhibit high stability under thermal and ambient conditions

Role of Mn2+ Doping in the Preparation of Core-Shell Structured Fe3O4@upconversion Nanoparticles and Their Applications in T1/T2-Weighted Magnetic Resonance Imaging, Upconversion Luminescent Imaging and Near-Infrared Activated Photodynamic Therapy

Core-shell (C/S) structured upconversion coated Fe3O4 nanoparticles (NPs) are of great interest due to their potential as magnetic resonance imaging (MRI) and upconversion luminescent (UCL) imaging agents, as well as near-infrared activated photodynamic therapy (PDT) platforms. When C/S structured Fe3O4@Mn2+-doped NaYF4:Yb/Er NPs were prepared previously, well-defined C/S-NPs could not be formed without the doping of Mn2+ during synthesis. Here, the role of Mn2+ doping on the synthesis of core-shell structured magnetic-upconversion nanoparticles (MUCNPs) is investigated in detail. Core-shell-shell nanoparticles (C/S/S-MUCNPs) with Fe3O4 as the core, an inert layer of Mn2+-doped NaYF4 and an outer shell consisting of Mn2+-doped NaYF4:Yb/Er were prepared. To further develop C/S/S-MUCNPs applications in the biological field, amphiphilic poly(maleic anhydride-alt-1-octadecene) (C18PMH) modified with amine functionalized methoxy poly(ethylene glycol) (C18PMH-mPEG) was used as a capping ligand to modify the surface of C/S/S-MUCNPs to improve biocompatibility. UCL imaging, T1-weighted MRI ascribed to the Mn2+ ions and T2-weighted MRI ascribed to the Fe3O4 core of C/S/S-MUCNPs were then evaluated. Finally, chlorine e6 (Ce6) was loaded on the C/S/S-MUCNPs and the PDT performance of these NPs was explored. Mn2+ doping is an effective method to control the formation of core-shell structured MUCNPs, which would be potential candidate as multifunctional nanoprobes for future T1/T2-weighted MR/UCL imaging and PDT platforms

In Situ Grain Boundary Modification via Two-Dimensional Nanoplates to Remarkably Improve Stability and Efficiency of Perovskite Solar Cells

Even though a record efficiency of 23.3% has been achieved in organic-inorganic hybrid perovskite solar cells, their stability remains a critical issue, which greatly depends on the morphology of perovskite absorbers. Herein, we report a practical grain boundary modification to remarkably improve the humidity and thermal stability by gradually growing in situ two-dimensional nanoplates between the grain boundaries of perovskite films using phenylethylammonium iodide (PEAT). The experimental results show that PEAL nanoplates play a critical role in stabilizing perovskite thin films by reducing the moisture sensitivity and suppressing phase transition at the grain boundaries. In addition to the significant improved ambient stability, the grain boundary modification by PEAL can effectively suppress the nonradiative charge recombination at grain boundaries. As a result, the efficiency of perovskite solar cells is up to 20.34% with significant humidity and thermal stability

Chelate-Pb Intermediate Engineering for High-Efficiency Perovskite Solar Cells

Crystallization quality and grain size are key factors in fabricating high-performance planar-type perovskite photovoltaics. Herein, we used 1,8-octanedithiol as an effective additive in the [HC-(NH2)(2)](0.95)CS0.05PbI3 (FA(0.95)Cs(0.05)PbI(3)) solution to improve the FA(0.95)Cs(0.05)PbI(3) film quality via solution processing. 1,8-Octanedithiol would coordinate with lead to form the chelate-Pb compound, leading to smaller Gibbs free energy during the perovskite crystallization process, facilitating formation of high-quality perovskite films with larger grains, smoother surfaces, lower electron trap densities, and longer carrier lifetimes compared to the nonadditive ones. As a result, the champion efficiency for devices with 3% 1,8-octanedithiol-doped FA(0.95)Cs(0.05)PbI(3) is raised to 19.36% from 18.39% of a device without the additive. The new technique is a promising way to fabricate perovskite photovoltaics with high performance

Effects of 5-Year Nitrogen Addition on Species Composition and Diversity of an Alpine Steppe Plant Community on Qinghai-Tibetan Plateau

The N deposition rate is notably increased in China, especially in the Qinghai-Tibetan Plateau (QTP). How plants respond to the projected N deposition on the alpine steppe is still in debate. In this study, to investigate the effects of N deposition on the plant community of the alpine steppe, we simulated N deposition at six different N addition rate levels (0, 8, 24, 40, 56, 72 kg N ha−1 y−1) from 2015 to 2019. Species composition and diversity were investigated as the assessment indices. The results showed that the importance value of grasses significantly increased with the increase of the N addition rate, while that of forbs significantly decreased. A high N addition rate (72 kg N ha−1 y−1) induced species composition change, making Leymus secalinus become the most dominant species within the entire plant community. Compared with the control (without N addition), species richness, Shannon–Weiner diversity, Simpson dominance and Pielou Evenness were significantly reduced under a high N addition rate. The changes of plant diversity in the alpine steppe were closely correlated with dynamics of soil nutrients, especially total carbon (TC), total phosphorus (TP) and ammonia nitrogen (NH4-N). Our findings suggested that a high N deposition rate (72 kg N ha−1 y−1) could significantly change plant composition and reduce the diversity of the alpine steppe, though they were less affected by low N deposition rates at present. With the increase of the N deposition rate, plant composition and diversity of the alpine steppe may be negatively affected in the future. In addition, Leymus secalinus is more competitive than other species with an N deposition rate increase. Soil C, soil P and soil NH4-N variation induced by N deposition might play a key role in regulating changes in plant composition and diversity in the alpine steppe. In addition, longer term field investigation needs to be carried out to testify to this phenomenon with the increase of N deposition in the future

High-Performance Inverted Perovskite Solar Cells by Reducing Electron Capture Region for Electron Transport Layers

The power conversion efficiency (PCE) of inverted perovskite solar cells (i-PSCs) is lower than that of the normal structures. The low efficiency is mainly ascribed to the inferior properties of commonly used [6,6]-phenyl C61 butyric acid methyl ester (PCBM) electron transport layers (ETLs) such as complexity in achieving high-quality films, low electron mobility, imperfect energy level for electron extraction, and large electron capture region. Herein, the bulk heterojunction (BHJ) ETLs composed of PCBM and polymers are developed. The electron mobility of the BHJ film is enhanced by more than three times compared with PCBM, leading to efficient electron extraction. The electron capture region of the BHJ film decreases to 1.20 x 10(-18) from 3.70 x 10(-17) cm(-3) for PCBM due to increased relative permittivity, which reduces the trap-assistant recombination at the interface. Meanwhile, the devices with BHJ exhibit good stability regardless of illumination and dark storage conditions owing to the more hydrophobic BHJ films and full coverage of perovskite surface, which effectively prevent the moisture permeation into the perovskite devices. It is believed that this breakthrough provides a suitable approach to improve the efficiency and stability of i-PSCs