With the increasing maturity of 5G technology and the comprehensive development of video apps on the Internet,the landscape of video app downloads shows that Migu Video lags behind giants like iQiyi,Tencent Video,Youk...With the increasing maturity of 5G technology and the comprehensive development of video apps on the Internet,the landscape of video app downloads shows that Migu Video lags behind giants like iQiyi,Tencent Video,Youku,and Mango TV.However,during the Tokyo Olympics and the Beijing Winter Olympics,Migu Video’s focus on sports coverage and commentary led to increased public use and app downloads.This study analyzes the marketing status and strategy of the Migu Video App.It conducts a detailed analysis using the 4I theory-interest,interaction,individuality,and initiative-and proposes a brand marketing strategy tailored for Migu Video.This aims to provide insights into the marketing strategies of other mobile Internet companies.展开更多
本文基于密度泛函理论(DFT)的第一性原理计算了W、Mn、V、Ti替位掺杂二维MoSi_(2)N_(4)后的几何结构、电子结构以及光学性质的变化.电子结构分析表明W、Mn、W、Ti替位掺杂二维MoSi_(2)N_(4)后的禁带宽度分别为1.806 e V、1.003 e V、1.2...本文基于密度泛函理论(DFT)的第一性原理计算了W、Mn、V、Ti替位掺杂二维MoSi_(2)N_(4)后的几何结构、电子结构以及光学性质的变化.电子结构分析表明W、Mn、W、Ti替位掺杂二维MoSi_(2)N_(4)后的禁带宽度分别为1.806 e V、1.003 e V、1.218 e V和1.373 e V;四种过渡金属掺杂后MoSi_(2)N_(4)的带隙类型没有发生改变,均为间接带隙半导体;W掺杂后的杂质能级靠近价带顶,费米能级靠近价带顶,为p型半导体,杂质能级为受主能级;Mn掺杂后的杂质能级靠近导带底,费米能级靠近导带底,为n型半导体;V和Ti掺杂后杂质能级位于费米能级附近,为复合中心;光学性质分析表明,在2 e V~4 e V的能量区间内,W掺杂结构的吸收波长为336 nm,体系发生红移;Mn、V和Ti替位掺杂后的吸收波长分别为320 nm、358 nm和338 nm,且掺杂体系均发生蓝移.展开更多
Efficient and selective glucose-to-fructose isomerization is a crucial step for production of oxygenated chemicals derived from sugars,which is usually catalyzed by base or Lewis acid heterogeneous catalyst.However,hi...Efficient and selective glucose-to-fructose isomerization is a crucial step for production of oxygenated chemicals derived from sugars,which is usually catalyzed by base or Lewis acid heterogeneous catalyst.However,high yield and selectivity of fructose cannot be simultaneously obtained under mild conditions which hamper the scale of application compared with enzymatic catalysis.Herein,a Li-promoted C_(3)N_(4) catalyst was exploited which afforded an excellent fructose yield(40.3 wt%)and selectivity(99.5%)from glucose in water at 50℃,attributed to the formation of stable Li–N bond to strengthen the basic sites of catalysts.Furthermore,the so-formed N_(6)–Li–H_(2)O active site on Li–C_(3)N_(4) catalyst in aqueous phase changes the local electronic structure and strengthens the deprotonation process during glucose isomerization into fructose.The superior catalytic performance which is comparable to biological pathway suggests promising applications of lithium containing heterogeneous catalyst in biomass refinery.展开更多
With the increasing popularity of new media,new media marketing plays an increasingly important role in the marketing of tourism scenic spots,bringing a new marketing opportunity to tourism scenic spots.Based on the 4...With the increasing popularity of new media,new media marketing plays an increasingly important role in the marketing of tourism scenic spots,bringing a new marketing opportunity to tourism scenic spots.Based on the 4R theory in marketing theory,this paper takes Quzhou Jianglang Mountain as the research object and finds that the following problems exist in the new media marketing of Quzhou Jianglang Mountain:1.The new media users are not closely enough connected;2.the response to the new media market changes is not fast enough;3.the new media marketing relationship interaction is not timely enough;and 4.the return of new media marketing is not ideal.The new media marketing strategy of Quzhou Jianglang Mountain Scenic Spot is proposed from four perspectives:association,reaction,relationship,and return.Finally,the research on the new media marketing strategy of Quzhou Jianglang Mountain Scenic Spot based on the 4R theory is summarized.展开更多
甘油是生物质精炼的主要副产物(约占10%),年过剩量与低利用率导致其市场价格(0.24-0.6 US kg^(-1))较低.甘油是具有三个活性羟基的多元醇,被认为是生产高价值产品的理想原料.甲酸作为甘油转化最重要的产品之一,广泛应用于农药、皮革、...甘油是生物质精炼的主要副产物(约占10%),年过剩量与低利用率导致其市场价格(0.24-0.6 US kg^(-1))较低.甘油是具有三个活性羟基的多元醇,被认为是生产高价值产品的理想原料.甲酸作为甘油转化最重要的产品之一,广泛应用于农药、皮革、染料和医药行业,将甘油电氧化(EGOR)为甲酸(FA)不仅能有效避免资源过剩造成浪费,而且能满足未来对甲酸燃料电池的需求.然而甘油电催化氧化途径较为复杂,涉及反应中间产物的脱氢、吸附/解吸和C-C键裂解.本文将密度泛函理论(DFT)与实验相结合,研究了在精细构建的NiCo_(2)O_(4)纳米片上通过EGOR生产FA的反应机制.DFT计算结果表明,活性羟基(OH^(*))物种可以改变EGOR生产FA过程的决速步骤(RDS),通过调节吸附中间体的吸附能可获得理想的FA产率.其中,高度羟基化的NiCo_(2)O_(4)纳米片(311)-OH^(*)晶面上具有最低的吉布斯自由能,能显著提升反应过程动力学.在理论分析的基础上,通过简易的电沉积方法精准制备了超薄NiCo_(2)O_(4)纳米片(~1.7 nm),并采用X射线吸收精细结构谱和高分辨透射电镜对催化剂进行了结构分析.结果表明,NiCo_(2)O_(4)纳米片中四面体(A_(Td))和八面体(B_(Oh))配位具有内角共享的A_(Td)-O-B_(Oh)和边共享的B_(Oh)-O-B_(Oh)构型,金属间的协同作用有效改善了材料的电子效应,有利于提供更多的吸附位点并促进EGOR过程中的电荷转移.NiCo_(2)O_(4)纳米片在EGOR中的电荷转移电阻仅为0.94Ω,电化学活性表面积高达10.25 cm^(2).相比较电催化析氧反应,NiCo_(2)O_(4)纳米片表现出了较好的EGOR性能,在10 mA cm^(-2)的电流密度下阳极功耗降低了320 mV,在100 mA cm^(-2)的电流密度时的阳极电势仅为1.46 VRHE.此外,在120 h的稳定性测试中,甘油的转化率和FA的选择性可分别保持在89%和70%.多电位步骤实验、原位电化学阻抗谱和电子顺磁共振谱结果表明,NiCo_(2)O_(4)纳米片上原位产生的OH^(*)物种是EGOR过程中的直接活性中心,有利于将RDS从甘油酸脱氢裂解转化为甘油醛的脱氢步骤,并进一步促进C-C键的裂解.进一步结合理论预测,证实了OH^(*)物种是EGOR过程中的直接活性中心.综上,采用绿色高效的电催化手段促进甘油生产高附加值化学品是生物质链升级的重要举措,有效避免了传统的高温高压,以水为介质,原位利用OH^(*).本文为新型催化剂的未来设计和理解生物质基原料电氧化升级反应机制提供了新思路.展开更多
The structures of the heptazine-based graphitic C3N4 and the S-doped graphitic C3N4 are investigated by using the density functional theory with a semi-empirical dispersion correction for the weak long-range interacti...The structures of the heptazine-based graphitic C3N4 and the S-doped graphitic C3N4 are investigated by using the density functional theory with a semi-empirical dispersion correction for the weak long-range interaction between layers.The corrugated structure is found to be energetically favorable for both the pure and the S-doped graphitic C3N4.The S doptant is prone to substitute the N atom bonded with only two nearest C atoms.The band structure calculation reveals that this kind of S doping causes a favorable red shift of the light absorption threshold and can improve the electroconductibility and the photocatalytic activity of the graphitic C3N4.展开更多
The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on ...The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on TiOz anatase（101） surface. Our calculations reveal that the surface-modified anatase system has large adsorption energy and a much narrower band gap. [Fe（CN）6]^4- adsorption on the （101） surface could lead to a large red shift of the anatase optical absorption threshold, which extends into a visible region significantly. The calculated results are in agreement with the experiment and other theoretical studies reasonably. It is very important for the understanding and further development ofphotovoltaic materials that are active under visible light.展开更多
This paper investigates the effect of Nb doping on the electronic structure and optical properties of Sr2TiO4 by the first-principles calculation of plane wave ultra-soft pseudo-potential based on density functional t...This paper investigates the effect of Nb doping on the electronic structure and optical properties of Sr2TiO4 by the first-principles calculation of plane wave ultra-soft pseudo-potential based on density functional theory （DFT）.The calculated results reveal that due to the electron doping,the Fermi level shifts into conduction bands（CBs） for Sr2NbxTi1-xO4 with x=0.125 and the system shows n-type degenerate semiconductor features. Sr2TiO4 exhibits optical anisotropy in its main crystal axes,and the c-axis shows the most suitable crystal growth direction for obtaining a wide transparent region.The optical transmittance is higher than 90% in the visible range for Sr2Nb0.125Ti0.875O4.展开更多
The paper introduces relevance theory and explores the application of relevance theory to CET-4 listening comprehension teaching, especially the teaching of CET-4 listening comprehension in the first section whose tes...The paper introduces relevance theory and explores the application of relevance theory to CET-4 listening comprehension teaching, especially the teaching of CET-4 listening comprehension in the first section whose test format is multiple choice question, simplified as MCQ.展开更多
基金Suihua University 2022 Project“Exploration and Practice of the Connotation Construction of Agricultural Product Circulation Discipline Professional Cluster”(Project No.2022007)。
文摘With the increasing maturity of 5G technology and the comprehensive development of video apps on the Internet,the landscape of video app downloads shows that Migu Video lags behind giants like iQiyi,Tencent Video,Youku,and Mango TV.However,during the Tokyo Olympics and the Beijing Winter Olympics,Migu Video’s focus on sports coverage and commentary led to increased public use and app downloads.This study analyzes the marketing status and strategy of the Migu Video App.It conducts a detailed analysis using the 4I theory-interest,interaction,individuality,and initiative-and proposes a brand marketing strategy tailored for Migu Video.This aims to provide insights into the marketing strategies of other mobile Internet companies.
文摘本文基于密度泛函理论(DFT)的第一性原理计算了W、Mn、V、Ti替位掺杂二维MoSi_(2)N_(4)后的几何结构、电子结构以及光学性质的变化.电子结构分析表明W、Mn、W、Ti替位掺杂二维MoSi_(2)N_(4)后的禁带宽度分别为1.806 e V、1.003 e V、1.218 e V和1.373 e V;四种过渡金属掺杂后MoSi_(2)N_(4)的带隙类型没有发生改变,均为间接带隙半导体;W掺杂后的杂质能级靠近价带顶,费米能级靠近价带顶,为p型半导体,杂质能级为受主能级;Mn掺杂后的杂质能级靠近导带底,费米能级靠近导带底,为n型半导体;V和Ti掺杂后杂质能级位于费米能级附近,为复合中心;光学性质分析表明,在2 e V~4 e V的能量区间内,W掺杂结构的吸收波长为336 nm,体系发生红移;Mn、V和Ti替位掺杂后的吸收波长分别为320 nm、358 nm和338 nm,且掺杂体系均发生蓝移.
基金The financial support from the National Natural Science Foundation of China(22278419,21978316,22108289,22172188)the Ministry of Science and Technology of China(2018YFB0604700)Suzhou Key Technology Research(Social Development)Project(2023ss06)。
文摘Efficient and selective glucose-to-fructose isomerization is a crucial step for production of oxygenated chemicals derived from sugars,which is usually catalyzed by base or Lewis acid heterogeneous catalyst.However,high yield and selectivity of fructose cannot be simultaneously obtained under mild conditions which hamper the scale of application compared with enzymatic catalysis.Herein,a Li-promoted C_(3)N_(4) catalyst was exploited which afforded an excellent fructose yield(40.3 wt%)and selectivity(99.5%)from glucose in water at 50℃,attributed to the formation of stable Li–N bond to strengthen the basic sites of catalysts.Furthermore,the so-formed N_(6)–Li–H_(2)O active site on Li–C_(3)N_(4) catalyst in aqueous phase changes the local electronic structure and strengthens the deprotonation process during glucose isomerization into fructose.The superior catalytic performance which is comparable to biological pathway suggests promising applications of lithium containing heterogeneous catalyst in biomass refinery.
基金sponsored by the following projects:Multi-modal Discourse Analysis of the Quzhou Government Affairs New Media(Grant No.202111488039).
文摘With the increasing popularity of new media,new media marketing plays an increasingly important role in the marketing of tourism scenic spots,bringing a new marketing opportunity to tourism scenic spots.Based on the 4R theory in marketing theory,this paper takes Quzhou Jianglang Mountain as the research object and finds that the following problems exist in the new media marketing of Quzhou Jianglang Mountain:1.The new media users are not closely enough connected;2.the response to the new media market changes is not fast enough;3.the new media marketing relationship interaction is not timely enough;and 4.the return of new media marketing is not ideal.The new media marketing strategy of Quzhou Jianglang Mountain Scenic Spot is proposed from four perspectives:association,reaction,relationship,and return.Finally,the research on the new media marketing strategy of Quzhou Jianglang Mountain Scenic Spot based on the 4R theory is summarized.
文摘甘油是生物质精炼的主要副产物(约占10%),年过剩量与低利用率导致其市场价格(0.24-0.6 US kg^(-1))较低.甘油是具有三个活性羟基的多元醇,被认为是生产高价值产品的理想原料.甲酸作为甘油转化最重要的产品之一,广泛应用于农药、皮革、染料和医药行业,将甘油电氧化(EGOR)为甲酸(FA)不仅能有效避免资源过剩造成浪费,而且能满足未来对甲酸燃料电池的需求.然而甘油电催化氧化途径较为复杂,涉及反应中间产物的脱氢、吸附/解吸和C-C键裂解.本文将密度泛函理论(DFT)与实验相结合,研究了在精细构建的NiCo_(2)O_(4)纳米片上通过EGOR生产FA的反应机制.DFT计算结果表明,活性羟基(OH^(*))物种可以改变EGOR生产FA过程的决速步骤(RDS),通过调节吸附中间体的吸附能可获得理想的FA产率.其中,高度羟基化的NiCo_(2)O_(4)纳米片(311)-OH^(*)晶面上具有最低的吉布斯自由能,能显著提升反应过程动力学.在理论分析的基础上,通过简易的电沉积方法精准制备了超薄NiCo_(2)O_(4)纳米片(~1.7 nm),并采用X射线吸收精细结构谱和高分辨透射电镜对催化剂进行了结构分析.结果表明,NiCo_(2)O_(4)纳米片中四面体(A_(Td))和八面体(B_(Oh))配位具有内角共享的A_(Td)-O-B_(Oh)和边共享的B_(Oh)-O-B_(Oh)构型,金属间的协同作用有效改善了材料的电子效应,有利于提供更多的吸附位点并促进EGOR过程中的电荷转移.NiCo_(2)O_(4)纳米片在EGOR中的电荷转移电阻仅为0.94Ω,电化学活性表面积高达10.25 cm^(2).相比较电催化析氧反应,NiCo_(2)O_(4)纳米片表现出了较好的EGOR性能,在10 mA cm^(-2)的电流密度下阳极功耗降低了320 mV,在100 mA cm^(-2)的电流密度时的阳极电势仅为1.46 VRHE.此外,在120 h的稳定性测试中,甘油的转化率和FA的选择性可分别保持在89%和70%.多电位步骤实验、原位电化学阻抗谱和电子顺磁共振谱结果表明,NiCo_(2)O_(4)纳米片上原位产生的OH^(*)物种是EGOR过程中的直接活性中心,有利于将RDS从甘油酸脱氢裂解转化为甘油醛的脱氢步骤,并进一步促进C-C键的裂解.进一步结合理论预测,证实了OH^(*)物种是EGOR过程中的直接活性中心.综上,采用绿色高效的电催化手段促进甘油生产高附加值化学品是生物质链升级的重要举措,有效避免了传统的高温高压,以水为介质,原位利用OH^(*).本文为新型催化剂的未来设计和理解生物质基原料电氧化升级反应机制提供了新思路.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB606403)the Doctoral Fund of the Ministry of Education of China (Grant No. 20090071120062)
文摘The structures of the heptazine-based graphitic C3N4 and the S-doped graphitic C3N4 are investigated by using the density functional theory with a semi-empirical dispersion correction for the weak long-range interaction between layers.The corrugated structure is found to be energetically favorable for both the pure and the S-doped graphitic C3N4.The S doptant is prone to substitute the N atom bonded with only two nearest C atoms.The band structure calculation reveals that this kind of S doping causes a favorable red shift of the light absorption threshold and can improve the electroconductibility and the photocatalytic activity of the graphitic C3N4.
基金the Scientific and Technology Foundation of Fuzhou University and the Key Project of Fujian Province (2005HZ01-2-6)
文摘The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on TiOz anatase（101） surface. Our calculations reveal that the surface-modified anatase system has large adsorption energy and a much narrower band gap. [Fe（CN）6]^4- adsorption on the （101） surface could lead to a large red shift of the anatase optical absorption threshold, which extends into a visible region significantly. The calculated results are in agreement with the experiment and other theoretical studies reasonably. It is very important for the understanding and further development ofphotovoltaic materials that are active under visible light.
基金Project supported by the Natural Science Foundation of ShaanXi Province of China (Grant No 2005F06)Northwest University(NWU) Graduate Innovation and Creativity Funds (Grant No 08YZZ47)
文摘This paper investigates the effect of Nb doping on the electronic structure and optical properties of Sr2TiO4 by the first-principles calculation of plane wave ultra-soft pseudo-potential based on density functional theory （DFT）.The calculated results reveal that due to the electron doping,the Fermi level shifts into conduction bands（CBs） for Sr2NbxTi1-xO4 with x=0.125 and the system shows n-type degenerate semiconductor features. Sr2TiO4 exhibits optical anisotropy in its main crystal axes,and the c-axis shows the most suitable crystal growth direction for obtaining a wide transparent region.The optical transmittance is higher than 90% in the visible range for Sr2Nb0.125Ti0.875O4.
文摘The paper introduces relevance theory and explores the application of relevance theory to CET-4 listening comprehension teaching, especially the teaching of CET-4 listening comprehension in the first section whose test format is multiple choice question, simplified as MCQ.
