氧化铝/氮化硅双层膜晶硅钝化的开尔文探针力显微镜研究

对晶体硅(c-Si)太阳能电池而言, 氧化铝(AlOx)是一种广泛使用的钝化材料, 因为它具有优异的沉积保形性和良好的钝化质量. 为了确保AlOx发挥其良好的钝化效果, 在沉积后退火并氢化处理是必不可少的. 通过在AlOx薄膜上沉积氢化氮化硅(SiNx:H)来实现氢化, 利用开尔文探针力显微镜研究了在不同热处理和氢化作用下, AlOx/SiNx:H双层薄膜功函数的变化, 并基于沉积薄膜所含氢与固定电荷展开了讨论. 发现钝化质量和功函数之间有相关性, 影响因素包括薄膜厚度、氢化与热处理顺序.     

Molecular design of ambipolar redox-active molecules II: closed-shell systems

This mini-review highlights key structural features that should be taken into account when creating ambipolar redox-active closed-shell metal-free molecules. This type of compound is strongly required for the fabrication of all-organic ‘poleless’ batteries and semiconductors. The suggested strategies aimed at stabilization of both oxidized (cationic) and reduced (anionic) redox-states are based on the comprehensive analysis of the most successful structures taken from the recent publications.     

Influence of ultrasound on the functional characteristics of indigenous varieties of mango (Mangifera indica L.)

The present study was conducted to evaluate the effect of ultrasonic (US) treatment on chemical characteristics and antioxidant potential of pulps obtained from eight mango varieties indigenous to Pakistan. There was a significant (p < 0.05) effect of varieties and US treatment on chemical characteristics i.e. pH, acidity, TSS, vitamin C contents, total sugars (%), reducing sugars (%) and non-reducing sugars (%). Microstructure evaluation of pulp from all mango varieties showed deshaped middle lamella and cell wall of cells after 8 min of US treatment. At 4 min of US treatment as per shaped cell wall and middle lamella, the chemical characteristics and antioxidant potential were higher. The total phenolics (TP), flavonoids (TF) and total antioxidant activity (TAA) of pulp from most varieties increased significantly (p < 0.05) after US treatment for 4 min but decreased successively after each treatment i.e. 8 and 12 min. The maximum value (314.17 μg AAE/mL pulp) of DPPH was shown by pulp from Dosehri and the minimum (158.67 μg AAE/mL pulp) was found in pulp from Langra before US treatment. The DPPH values of pulp from most of the varieties increased significantly (p < 0.05) after US treatment for 4 min but decreased successively after each treatment but pulp from Langra showed increasing trend after 8 min of US treatment which decreased after 12 min of treatment. The total anthocyanin (TA) values of pulp from Chaunsa, Dosehri, Sindhri, Gulab Khas and Langra increased abruptly after US treatment for 4 min but decreased successively after subsequent treatment. The pulp from Desi, Anwar Ratol, Gulab Khas and Langra showed an abrupt decrease in TA after 8 min of US treatment. An increasing trend of values of total carotenoids (TC) was shown by pulp from all mango varieties after 4 min of US treatment but decreasing trend was observed with subsequent increase in time of US treatment.     

三维位势问题的梯度边界积分方程的新解法

三维位势问题的边界元分析中,关于坐标变量的边界位势梯度的计算是一个困难的问题. 已有一些方法着手解决这个问题,然而,这些方法需要复杂的理论推导和大量的数值计算. 本文提出求解一般边界位势梯度边界积分方程的辅助边值问题法. 该方法构造了与原边界值问题具有相同解域的辅助边值问题,该辅助边值问题具有已知解,因此通过求解此辅助边值问题,可获得梯度边界积分方程对应的系统矩阵,然后将此系统矩阵应用于求解原边值问题,求解过程非常简单,只需求解一个线性系统即可获得原边值问题的解. 值得注意的是,在求解原边值问题时,不再需要重新计算系统矩阵,因此辅助边值问题法的效率并不很差. 辅助边值问题法避免了强奇异积分的计算,具有数学理论简单、程序设计容易、计算精度高等优点,为坐标变量梯度边界积分方程的求解提供了一个新的途径. 3个标准的数值算例验证了方法的有效性.      

Negatively Charged Metallacarborane Redox Couples with Both Members Stable to Air

The metallacarborane [3,3′‐Co(1,2‐closo‐C₂B₉H₁₁)₂]^? has been synthesized. This species allows the formation of redox couples in which both partners are negatively charged. The E_1/2 potential can be tuned by adjusting the nature and number of substituents on B and C. The octaiodinated species [3,3′‐Co(1,2‐closo‐C₂B₉H₇I₄)₂]^? is the most favorable, as it is isolatable and stable in air. A DFT study on stability and redox potentials of complexes has been performed.     

Quinones for redox flow batteries

Quinones are electroactive species that have shown great promise for redox flow batteries due to the ability to tune their properties and to act as both negative and positive electrolytes. The following review outlines highlights of work in the last couple of years working to provide materials with higher stability, solubility, and performance. Developments toward stable negolytes have provided opportunities for potential commercial opportunities when paired with alternate chemistries. However, the stability of quinones in high potential electrolytes is still not sufficient and the number of potential quinones limited.     

Methyl orange degradation enhanced by hydrogen spillover onto platinum nanocatalyst surface

Following a thermal reduction method, platinum nanoparticles were synthesized and stabilized by polyvinylpyrrolidone. The colloidal platinum nanoparticles were stable for more than 3 months. The micrograph analysis unveiled that the colloidal platinum nanoparticles were well dispersed with an average size of 2.53 nm. The sol–gel‐based inverse micelle strategy was applied to synthesize mesoporous iron oxide material. The colloidal platinum nanoparticles were deposited on mesoporous iron oxide through the capillary inclusion method. The small‐angle X‐ray scattering analysis indicated that the dimension of platinum nanoparticles deposited on mesoporous iron oxide (Pt‐Fe₂O₃) was 2.64 nm. X‐ray photoelectron spectroscopy (XPS) data showed that the binding energy on Pt‐Fe₂O₃ surface decreased owing to mesoporous support–nanoparticle interaction. Both colloidal and deposited platinum nanocatalysts improved the degradation of methyl orange under reduction conditions. The activation energy on the deposited platinum nanocatalyst interface (2.66 kJ mol^?1) was significantly lowered compared with the one on the colloidal platinum nanocatalyst interface (40.63 ± 0.53 kJ mol^?1).     

The energy-critical nonlinear wave equation with an inverse-square potential

We study the energy-critical nonlinear wave equation in the presence of an inverse-square potential in dimensions three and four. In the defocussing case, we prove that arbitrary initial data in the energy space lead to global solutions that scatter. In the focusing case, we prove scattering below the ground state threshold.     

Revealing and comparing different excited-state intramolecular proton transfer processes for 3-(4-dimethylamino-phenyl)-1-(4-fluoro-2-hydroxy-phenyl)-propenone and 3-(4-dimethylamino-phenyl)-1-(4-fluoro-2-hydroxy-phenyl)-3-hydroxy-propenon

Two novel 2′-hydroxychalcone derivatives (i.e., M1 and M2) are explored in this work. We mainly focus on investigating the effects of photoexcitation on hydrogen bonds and on the excited-state intramolecular proton transfer (ESIPT) process. On the basis of calculations of electrostatic potential surface and intramolecular interactions, we verify the formation of hydrogen bond O1 H2···O3 in both S₀ and S₁ states. Exploring the ultraviolet–visible spectra in the liquid phase, our simulated results reappear in the experimental phenomenon. Analyzing molecular geometry and infrared stretching vibrational spectra, we confirm O1 H2···O3 is strengthened for both M1 and M2 in the S₁ state. We further confirm that charge redistribution facilitates ESIPT tendency. Constructing potential energy curves, we find the ultrafast ESIPT behavior for M1, which is because of the deficiency of side hydroxyl moiety comparing with M2. This work makes a reasonable affiliation of the ESIPT mechanism for M1 and M2. We wish this paper could facilitate understanding these two novel systems and promote their applications.