Current progresses in two-dimensional MXene-based framework: prospects from superficial synthesis to energy conversion and storage applications

MXenes are regarded as a type of two-dimensional (2D) inorganic material, mainly comprising a number of transition metal carbides, nitrides, or carbonitrides atomic planes. Nevertheless, the scientific community is continuously interested in exploring and structuring the engineered-based multifunctional material for numerous applications. The MXenes-based materials in this context, have emerged as highly active compounds owing to their superior surface area, substantial interlayer spacing, highly reactive surface-active sites and surface functional group, even though, recent studies have shown significant scientific and theoretical progress related to enormous prospects in MXenes, chemical nature, robust electrochemistry and high hydrophilicity of MXenes. The role of MXenes in all kinds of strategies is still in an upgrading phase for their further improvement, and is not sufficiently summarized in the literature now. To begin with this, herein, present review article is intended to critically discuss the diversity of MXenes with respect to different composition, formulation, plasmonic, complexation, and numerous geometric and morphological aspects, along with novel construction strategies to improve their surface characteristics in all aforesaid multidimensional applications. Following that, in terms of broadening the application, this review article is envisaged to endorse the use of MXenes and their hybrid configuration in a series of emerging environmental decontamination via adsorption, photodegradation, photocatalytic fuel production via hydrogen evolution, CO₂ reduction, electrocatalytic sensing, along with membrane distillation and energy storage. In addition, comprehensive information about existing obstacles and future perspectives have been addressed. Finally, an overview is succinctly summarized and discussed regarding the emerging prospects of MXenes for their potential uses in numerous research fields. At the end, it is anticipated that this review article will pave the way for the effective use of MXenes in different fields of environmental remediation, energy conversion, storage and biomedical applications as an innovative, reliable, and multifunctional material.     

A mini-review of recent progress in lead dioxide electrocatalyst for degradation of toxic organic pollutants

Lead dioxide (PbO₂) electrocatalyst as a non-active anode have been extensively investigated in recent years with environmental objectives for the degradation of organic pollutants. Degradation of organics at the surface of the PbO₂ anode by direct and indirect oxidation mechanisms proceeds to complete mineralization under optimal conditions. However, for conventional Ti/PbO₂ anodes, low oxygen evolution potential (OEP), short service time, lead leakage, mass transfer limitation and, low active surface area are still the most important disadvantages that need much study. Development of PbO₂ electrocatalysts with a three-dimensional structure, use of innovative intermediate layers, and doping of the main electrocatalyst active layer with the aim of increasing active sites are among the new strategies for upgrading PbO₂ anodes. Focusing on articles published since 2021, this review presents current efforts by researchers to improve the electrocatalytic performance, stability and, environmental safety of PbO₂ anodes for improved degradation of environmental pollutants.     

几何平均下的水平重置期权定价

针对重置期权的风险对冲△跳现象,研究了一种亚式特征的水平重置期权的定价问题.首先在BS模型下用股票的几何平均价格作为水平重置期权执行价格重置与否的统计量,然后运用测度变换和鞅定价方法得到了风险中性定价公式,最后利用风险中性定价公式得出风险对冲△值的显示解,改进了水平重置期权的部分已有结果.     

Asset allocation,sustainable withdrawal,longevity risk and non-exponential discounting

The present paper studies an optimal withdrawal and investment problem for a retiree who is interested in sustaining her retirement consumption above a pre-specified minimum consumption level. Apparently, the withdrawal and investment policy depends substantially on the retiree’s health condition and her time preferences (subjective discount factor). We assume that the health of the retiree can worsen or improve in an unpredictable way over her lifetime and model the retiree’s mortality intensity by a stochastic process. In order to make the decision about the consumption and investment policy more realistic, we assume that the retiree applies a non-exponential discount factor (an exponential discount factor with a small amount of hyperbolic discounting) to value her future income. In other words, we consider an optimization problem by combining four important aspects: asset allocation, sustainable withdrawal, longevity risk and non-exponential discounting. Due to the non-exponential discount factor, we have to solve a time-inconsistent optimization problem. We derive a non-local HJB equation which characterizes the equilibrium optimal investment and consumption strategy. We establish the first-order expansions of the equilibrium value function and the equilibrium strategies by applying expansion techniques. The expansion is performed on the parameter controlling the degree of discounting in the hyperbolic discounting that is added to the exponential discount factors. The first-order equilibrium investment and consumption strategies can be calculated in a feasible way by solving PDEs.     

Levels of arithmetic reasoning in solving an open-ended problem

This paper presents the results of an experimental teaching carried out on 12-year-old students. An open-ended task was given to them and they had not been taught the algorithmic process leading to the solution. The formal solution to the problem refers to a system of two linear equations with two unknown quantities. In this mathematical activity, students worked cooperatively. They discussed their discoveries in groups of four and then presented their answers to the whole class developing a rich communication. This study describes the characteristic arguments that represent certain different forms of reasoning that emerged during the process of justifying the solutions of the problem. The findings of this research show that within an environment conducive to creativity, which encourages collaboration, exploration and sharing ideas, students can be engaged in developing multiple mathematical strategies, posing new questions, creating informal proofs, showing beauty and elegance and bringing out that problem solving is a powerful way of learning mathematics.     

分形市场中具有时变利率的欧式外汇期权定价

选取最一般的外汇期权作为研究对象,在分形-Ito-积分下证明国内国外无风险利率均为关于时间t的非随机函数时的欧式外汇看涨和看跌期权价格公式,并说明经典Black—Scholes期权定价公式是本公式的特例。     

英语短文改错中的介词误用及对策

介词虽然在词汇表中所占比重相对较小,但是用法却很灵活,使用率也极高。中同学生一向对介词感到束手无策。介词主要涉及用法与搭配,是短文改错中出现频率最高,也是考生最易失分的一类题型。文章对介词的用法特点及其误用情况进行分析并提出相应的教学策略。     

大学生特殊群体体育教学分析与对策

文章主要采用文献资料法、问卷调查法、访谈法、数理统计法对浙江万里学院特殊群体的体育教学现状、内容、评价体系及学生满意度进行分析与探讨,针对性的提出了加强经费投入、师资建设、多样化教学、完善评价体系,完善学生人格的建议。     

物理教学中促进自主学习的合作学习策略

自主学习是当今教育研究的一个重要课题。以大学物理教学为例,分析大学生的认知发展特点及自主学习状况,以及合作学习的教学价值,通过合作学习形式,培养学生自主学习能力。     

元认知策略应用于高职高专英语听力教学的实证研究

本研究以一所职业技术学院两个自然班的73名学生为调查对象,分析元认知策略使用与英语听力之间的关系。研究结果显示:(1)元认知策略的培训能有效提高高职高专学生的听力理解水平;(2)大多数学生的元认知意识在培训后都有显著提高;(3)听力能力强的学生使用元认知策略的频率高于听力能力弱的学生;(4)在听力理解能力的提高程度上,能力弱的学生提高的程度高于能力强的学生,这说明元认知策略的培训对听力能力弱的学生更具有潜力。