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2-D Modeling and Calculations of Stratospheric Ozone and Influences of Convection, Diffusion, and Time
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作者 Ibraheem Alelmi Laurie Wei Sen Nieh 《Atmospheric and Climate Sciences》 2024年第2期250-276,共27页
An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical react... An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical reaction equations was developed, validated, and used for studying the ozone concentrations, distribution and peak of the layer, ozone depletion and total ozone abundance in the stratosphere. The calculated ozone concentrations and profile at both the Equator and a 60˚N location were found to follow closely with the measured data. The calculated average ozone concentration was within 1% of the measured average, and the deviation of ozone profiles was within 14%. The monthly evolution of stratospheric ozone concentrations and distribution above the Equator was studied with results discussed in details. The influences of slow air movement in both altitudinal and radial directions on ozone concentrations and profile in the stratosphere were explored and discussed. Parametric studies of the influences of gas diffusivities of ozone D<sub>O3</sub> and active atomic oxygen D<sub>O</sub> on ozone concentrations and distributions were also studied and delineated. Having both influences through physical diffusion and chemical reactions, the diffusivity (and diffusion) of atomic oxygen D<sub>O</sub> was found to be more sensitive and important than that of ozone D<sub>O3</sub> on ozone concentrations and distribution. The 2-D ozone model present in this paper for stratospheric ozone and its layer and depletion is shown to be robust, convenient, efficient, and executable for analyzing the complex ozone phenomena in the stratosphere. . 展开更多
关键词 Stratospheric Ozone 2-d Model Ozone Layer Ozone Depletion CONVECTION DIFFUSION
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Calculations and Sensitivity Analysis of Chlorine-,NO_(x)-,and Bromine-Depleting Cycles of Stratospheric Ozone
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作者 Ibraheem Alelmi Sen Nieh 《Journal of Environmental Science and Engineering(B)》 CAS 2024年第2期53-69,共17页
This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozon... This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozone-generating,and-depleting chemical reactions,the model calculated the transient,spatial changes of ozone under different physical-chemical-radiative conditions.Validation against the measured data demonstrated good accuracy,close match of our model with the observed ozone concentrations at both 20°S and 90°N locations.The deviation in the average concentration was less than 1% and in ozone profiles less than 17%.The impacts of various chlorine-(Cl),nitrogen oxides-(NO_(x)),and bromine-(Br)depleting cycles on ozone concentrations and distribution were investigated.The chlorine catalytic depleting cycle was found to exhibit the most significant impact on ozone dynamics,confirming the key role of chlorine in the problem of ozone depletion.Sensitivity analysis was conducted with levels of 25%,50%,100%,200%,and 400% of the baseline value.The combined cycles(Cl+NO_(x)+Br)showed the most significant influence on ozone behavior.The total ozone abundance above the South Pole could decrease by a small 3%,from 281 DU(Dubson Units)to 273 DU for the 25% level,or by a huge thinning of 60%to 114 DU for the 400% concentration level.When the level of chlorine gases increased beyond 200%,it would cause ozone depletion to a level of ozone hole(below 220 DU).The 2D Ozone Model presented in this paper demonstrates robustness,convenience,efficiency,and executability for analyzing complex ozone phenomena in the stratosphere. 展开更多
关键词 Ozone depletion 2-d model CHLORINE BROMINE nitrogen oxides sensitivity analysis total ozone abundance DU
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一种基于三角数分解的可配置2-D卷积器优化方法
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作者 黄继业 肖强 +4 位作者 田大海 高明裕 王俊帆 董哲康 黄汐威 《电子与信息学报》 EI CAS CSCD 北大核心 2024年第7期3054-3062,共9页
多尺寸2-D卷积通过特征提取在检测、分类等计算机视觉任务中发挥着重要作用。然而,目前缺少一种高效的可配置2-D卷积器设计方法,这限制了卷积神经网络(CNN)模型在边缘端的部署和应用。该文基于乘法管理以及奇平方数的三角数分解方法,提... 多尺寸2-D卷积通过特征提取在检测、分类等计算机视觉任务中发挥着重要作用。然而,目前缺少一种高效的可配置2-D卷积器设计方法,这限制了卷积神经网络(CNN)模型在边缘端的部署和应用。该文基于乘法管理以及奇平方数的三角数分解方法,提出一种高性能、高适应性的卷积核尺寸可配置的2-D卷积器。所提2-D卷积器包含一定数量的处理单元(PE)以及相应的控制单元,前者负责运算任务,后者负责管理乘法运算的组合,二者结合以实现不同尺寸的卷积。具体地,首先根据应用场景确定一个奇数列表,列表中为2-D卷积器所支持的尺寸,并利用三角数分解得到对应的三角数列表;其次,根据三角数列表和计算需求,确定PE的总数量;最后,基于以小凑大的方法,确定PE的互连方式,完成电路设计。该可配置2-D卷积器通过Verilog硬件描述语言(HDL)设计实现,由Vivado 2 022.2在XCZU7EG板卡上进行仿真和分析。实验结果表明,相比同类方法,该文所提可配置2-D卷积器,乘法资源利用率得到显著提升,由20%~50%提升至89%,并以514个逻辑单元实现1 500 MB/s的吞吐率,具有广泛的适用性。 展开更多
关键词 2-d卷积器 可配置架构 乘法管理 三角数分解
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基于离散2-D小波多级分解的电容器外观缺陷视觉检测方法
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作者 张剑 高云 何栋 《电子器件》 CAS 2024年第5期1255-1260,共6页
电容器外观破损、凸起等缺陷直接影响器件的生产质量。目前电容器微小外观缺陷检测难度较大,导致视觉检测效率较低。为此提出了基于离散2-D小波多层分解的电容器外观缺陷视觉检测方法。采用同态滤波处理去除光照对电容器外观视觉检测结... 电容器外观破损、凸起等缺陷直接影响器件的生产质量。目前电容器微小外观缺陷检测难度较大,导致视觉检测效率较低。为此提出了基于离散2-D小波多层分解的电容器外观缺陷视觉检测方法。采用同态滤波处理去除光照对电容器外观视觉检测结果的影响。利用像素点灰度值确定图像边缘点位置,提取电容器外观缺陷区域。应用离散2-D小波分解的方法对其展开多级分解。再差分统计电容器图像的外观缺陷纹理特征。将特征输入Mahalanobis分类器中,完成电容器外观缺陷视觉检测。仿真结果表明,所提方法可以较好检测电容的各种缺陷,召回率最低值是94.9%,误检率最高值为9.8%,漏检率均在10%以内,电容器缺陷检测效果较好。 展开更多
关键词 多尺度特征 同态滤波处理 2-d小波分解 Mahalanobis分类器 电容缺陷 视觉检测
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2,4-D处理对欧李果实钙摄取的影响及与有机酸代谢和IAA的关系
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作者 苏国是 张莉 +3 位作者 刘锁仝 李晓艳 覃志茂 郭金丽 《植物研究》 CAS CSCD 北大核心 2024年第6期832-842,共11页
为探究外源植物生长调节剂2,4-D处理对欧李(Cerasus humilis)果实发育成熟过程中钙素摄取能力的影响及与有机酸代谢、生长素(IAA)之间的关系,以内蒙古地区的低钙欧李MY-9果实为试材,以清水喷施作为对照,研究2,4-D处理对果实发育成熟过... 为探究外源植物生长调节剂2,4-D处理对欧李(Cerasus humilis)果实发育成熟过程中钙素摄取能力的影响及与有机酸代谢、生长素(IAA)之间的关系,以内蒙古地区的低钙欧李MY-9果实为试材,以清水喷施作为对照,研究2,4-D处理对果实发育成熟过程中钙摄取能力和有机酸代谢及IAA的影响,并进行相关性分析。结果表明(:1)在摄钙速率方面,处理与对照果实的果胶钙、活性钙、总钙的摄钙速率变化规律相似,均表现为先升后降,处理后从硬核期到完熟期以上3种钙的摄取速率均显著高于对照;而水溶钙摄钙速率与其相反,表现为先降后升,果实发育后期显著高于对照。在摄钙活性方面,4种钙形态的变化规律相似,均表现为持续下降,处理后果实的摄钙活性均显著高于对照。在相对生长钙摄取量方面,4种钙形态的变化规律一致,均表现为先升后降,硬熟期和完熟期处理显著高于对照。(2)处理与对照果实中苹果酸脱氢酶(NAD-MDH)活性、苹果酸及有机酸含量随着果实发育成熟均呈上升趋势,苹果酸酶(NADP-ME)活性和柠檬酸含量均呈下降趋势,2,4-D处理可以不同程度提高果实中有机酸含量及相关酶活性。(3)处理与对照果实的IAA含量整体上均表现为先升后降,整个发育时期处理与对照均存在显著差异,2,4-D处理可显著提升欧李果实IAA含量。(4)相关性分析表明,水溶钙的摄钙速率和相对生长钙摄取量与NAD-MDH活性、苹果酸及有机酸含量均呈显著正相关,与IAA含量、NADP-ME活性及柠檬酸含量呈显著负相关;果胶钙、活性钙及总钙的摄钙活性与IAA含量、NADP-ME活性、柠檬酸含量呈显著正相关,与NAD-MDH活性、苹果酸及有机酸呈显著负相关;2,4-D处理提升了果实钙摄取能力与柠檬酸含量的相关性。综上所述,2,4-D处理可以提高欧李果实中钙摄取能力,提高有机酸代谢及IAA含量;欧李果实中钙摄取能力与有机酸代谢及IAA含量密切相关,随着NAD-MDH活性增强,苹果酸含量增加,有机酸含量增加,会提高水溶钙摄取能力,但会降低果胶钙、活性钙及总钙的摄取能力;而柠檬酸及IAA含量的增加会降低水溶钙摄取能力,提高果胶钙、活性钙及总钙摄取能力。2,4-D处理通过提高有机酸代谢及IAA含量调控果实钙摄取。 展开更多
关键词 欧李果实 2 4-d 钙摄取 有机酸代谢 生长素
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Two-dimensional Cr_(2)Cl_(3)S_(3) Janus magnetic semiconductor with large magnetic exchange interaction and high-T_(C)
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作者 Lei Fu Shasha Li +3 位作者 Xiangyan Bo Sai Ma Feng Li Yong Pu 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期481-485,共5页
The two-dimensional(2D)Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures.Van der Waals CrCl_(3) monolayer has been experimentally proved to... The two-dimensional(2D)Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures.Van der Waals CrCl_(3) monolayer has been experimentally proved to have an in-plane magnetic easy axis and a low Curie temperature of 17 K,which will limit its application in spintronic devices.In this work,we propose a new Janus monolayer Cr_(2)Cl_(3)S_(3) based on the first principles calculations.The phonon dispersion and elastic constants confirm that Janus monolayer Cr_(2)Cl_(3)S_(3) is dynamically and mechanically stable.Our Monte Carlo simulation results based on magnetic exchange constants reveal that Janus monolayer Cr_(2)Cl_(3)S_(3) is an intrinsic ferromagnetic semiconductor with TC of 180 K,which is much higher than that of CrCl_(3) due to the enhanced ferromagnetic coupling caused by S substitution.Moreover,the magnetic easy axis of Janus Cr_(2)Cl_(3)S_(3) can be tuned to the perpendicular direction with a large magnetic anisotropy energy(MAE)of 142eV/Cr.Furthermore,the effect of biaxial strain on the magnetic property of Janus monolayer Cr_(2)Cl_(3)S_(3) is evaluated.It is found that the Curie temperature is more robust under tensile strain.This work indicates that the Janus monolayer Cr_(2)Cl_(3)S_(3) presents increased Curie temperature and out-of-plane magnetic easy axis,suggesting greater application potential in 2D spintronic devices. 展开更多
关键词 first-principles calculations 2D materials magnetic properties ferromagentic semiconductor
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Solar-driven CO_(2) conversion to methane and methanol using different nanostructured Cu_(2)O-based catalysts modified with Au nanoparticles
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作者 João Angelo Lima Perini Lilian D.Moura Torquato +7 位作者 Juliana Fde Brito Gustavo A.Andolpho Mateus A.Gonçalves Leonardo D.De Angelis Lucas D.Germano Susana I.Córdoba de Torresi Teodorico C.Ramalho Maria V.Boldrin Zanoni 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第4期287-298,共12页
This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of ... This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of polydopamine was used as both an adherent agent and an electron transfer mediator,due to itsπ-conjugated electron system.The highest production yield was achieved using a TNT@PDA/Nc/Au40%electrode,with Faradaic efficiencies of 47.4%(110.5μM cm^(-2))and 27.8%(50.4μM cm^(-2))for methanol and methane,respectively.The performance of the photoelectrodes was shown to be Cu_(2)O facet-dependent,with cubic structures leading to greater conversion of CO_(2)to methanol(43%)and methane(27%),compared to the octahedral morphology,while a higher percentage of metallic gold on the nanostructured Cu_(2)O surface was mainly important for CH4production.Density functional theory(DFT)calculations supported these findings,attributing the superior photoelectrocatalytic performance of the TNT@PDA/Nc/Au40%electrode for CH4generation to the formation of an OCH3intermediate bonded to Au atoms.Studies using isotope-labeling and analysis by gas chromatograph-mass(GC-MS)demonstrated that13CO_(2)was the source for photoelectrocatalytic generation of13CH3OH and13CH313CH2OH. 展开更多
关键词 Cu_(2)O nanocubes PHOTOELECTROCATALYSIS POLYDOPAMINE CO_(2) photoelectroreduction DFT calculations
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Delving into the dissimilarities in electrochemical performance and underlying mechanisms for sodium and potassium ion storage in N-doped carbon-encapsulated metallic Cu_(2)Se nanocubes
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作者 Xinyu Wang Yanan Xu +4 位作者 Xiaofeng Liu Lei Tan Huaiqiang Gu Xin Du Dan Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第8期336-347,I0008,共13页
The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical perfo... The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical performance.Herein,metallic Cu_(2)Se encapsulated with N-doped carbon(Cu_(2)Se@NC)was prepared using Cu_(2)O nanocubes as templates through a combination of dopamine polymerization and hightemperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu_(2)Se@NC with excellent electrochemical performance in sodium ion batteries(SIBs)and potassium ion batteries(PIBs).The composite exhibited excellent rate performance(187.7 mA h g^(-1)at 50 A g^(-1)in SIBs and 179.4 mA h g^(-1)at 5 A g^(-1)in PIBs)and cyclic stability(246,8 mA h g^(-1)at 10 A g^(-1)in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction(XRD)and ex situ transmission electron microscope(TEM).In particular,the final products in PIBs of K_(2)Se and K_(2)Se_(3)species were determined after discharging,which is different from that in SIBs with the final species of Na_(2)Se.The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu_(2)Se,leading to the introduction of built-in electric field on heterojunction to improve electron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na~+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems. 展开更多
关键词 Cu_(2)Se nanocubes DFT calculations Ion storage mechanism Potassium ion batteries Sodium ion batteries
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基于二萘并[2,3-B∶2′,3′-D]呋喃基团的高效窄发射蓝光OLED器件
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作者 王小伟 袁江波 +4 位作者 马佩兰 闫自强 崔志远 孙军 彭其明 《发光学报》 EI CAS CSCD 北大核心 2024年第9期1503-1510,共8页
高效率窄光谱蓝色有机电致发光器件(OLED)是柔性显示领域的研究重点之一。本文以二萘并[2,3-B∶2′,3′-D]呋喃为弱电子受体、N-(4-联苯基)-1-萘胺作为电子给体设计合成了一种D-A-D型蓝光分子DPF-NA,其在正己烷溶液中的发射峰位于441 n... 高效率窄光谱蓝色有机电致发光器件(OLED)是柔性显示领域的研究重点之一。本文以二萘并[2,3-B∶2′,3′-D]呋喃为弱电子受体、N-(4-联苯基)-1-萘胺作为电子给体设计合成了一种D-A-D型蓝光分子DPF-NA,其在正己烷溶液中的发射峰位于441 nm。理论计算与光物理测试结果显示DPF-NA具有杂化局域电荷转移激发态(HLCT)特性,兼具局域态(LE)高发光效率与电荷转移态(CT)高激子利用率特征,在二氯甲烷溶液中的光致发光量子效率(PLQY)为81.2%。基于质量分数3%DPF-NA掺杂浓度的OLED器件电致发光(EL)峰位于455 nm,半峰宽(FWHM)仅为26 nm,CIE(x,y)坐标为(0.14,0.08),最大外量子效率(EQEmax)为6.76%。 展开更多
关键词 有机电致发光器件 二萘并[2 3-B∶2 3′-d]呋喃 蓝光 激子利用 外量子效率
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New 4-imino-4H-Chromeno[2,3-d]Pyrimidin-3(5H)-Amine: Synthesis, Cytotoxic Effects on Tumoral Cell Lines and in Silico ADMET Properties
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作者 Marwa Dhiabi Sirine Karoui +7 位作者 Mehdi Fakhfakh Souhir Abid Emmanuelle Limanton Rémy Le Guével Thierry Charlier Ludovic Paquin Jean-Pierre Bazureau Houcine Ammar 《International Journal of Organic Chemistry》 2024年第3期107-122,共16页
The synthesis of new 4-imino-4H-chromeno[2,3-d]pyrimidin-3(5H)-amine in four steps including one step under microwave dielectric heating is reported. The structural identity of the synthesized compounds was establishe... The synthesis of new 4-imino-4H-chromeno[2,3-d]pyrimidin-3(5H)-amine in four steps including one step under microwave dielectric heating is reported. The structural identity of the synthesized compounds was established according to their spectroscopic analysis, such as FT-IR, NMR and mass spectroscopy. These new compounds were tested for their antiproliferative activities on seven representative human tumoral cell lines (Huh7 D12, Caco2, MDA-MB231, MDA-MB468, HCT116, PC3 and MCF7) and also on fibroblasts. Among them, only the compounds 6c showed micromolar cytotoxic activity on tumor cell lines (1.8 50 50 > 25 μM). Finally, in silico ADMET studies ware performed to investigate the possibility of using of the identified compound 6c as potential anti-tumor compound. 展开更多
关键词 2-Amino-4H-Chromene 4H-Chromeno[2 3-d]Pyrimidin-3(5H)-Amine Microwave Irradiation Tumoral Cell Line in Silico ADMET
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Structural,electronic,and Li-ion mobility properties of garnet-type Li_(7)La_(3)Zr_(2)O_(12) surface:An insight from first-principles calculations
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作者 王靖轩 孙宝珍 +2 位作者 李梅 吴木生 徐波 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第6期652-659,共8页
Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the st... Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the stability,electronic properties,and Li-ion mobility of the LLZO surface by the ifrst-principles calculations.We consider the(110) and(001) slab structures with different terminations in the t-and c-LLZO.Our results indicate that both(110) and(001) surfaces prefer to form Li-rich termination due to their low surface energies for either t-or c-LLZO.Moreover,with the decrease of Li contents the stability of Li-rich surfaces is improved initially and degrades later.Unfortunately,the localized surface states at the Fermi level can induce the formation of metallic Li on the Li-rich surfaces.In comparison,Li/La-termination has a relatively low metallic Li formation tendency due to its rather low diffusion barrier.In fact,Li-ion can spontaneously migrate along path II(Li3→Li2) on the Li/La-T(001) surface.In contrast,it is more difficult for Li-ion diffusion on the Li-T(001) surface,which has a minimum diffusion barrier of 0.50 eV.Interestingly,the minimum diffusion barrier decreases to 0.34 eV when removing four Li-ions from the Li-T(001) surface.Thus,our study suggests that by varying Li contents,the stability and Li-ion diffusion barrier of LLZO surfaces can be altered favorably.These advantages can inhibit the formation of metallic Li on the LLZO surfaces. 展开更多
关键词 solid-state electrolyte Li_(7)La_(3)Zr_(2)O_(12)(LLZO)surface Li-ion migration first-principles calculations
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Synthesis, Crystal Structure and Theoretical Calculation of [2-(2,6-Dioxacyclohexyl)-5-methoxylphenols]_2 被引量:1
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作者 段文增 冯帅 +1 位作者 孙斌 吴仁涛 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第10期1290-1295,共6页
The title compound [2-(2,6-dioxacyclohexyl)-5-methoxylphenols]2 was synthesized by the reaction of 2-hydroxyl-3-methoxylbenzaldehyde and 1,3-propanediol in the presence of DMF-DMS adduct and characterized by IR spec... The title compound [2-(2,6-dioxacyclohexyl)-5-methoxylphenols]2 was synthesized by the reaction of 2-hydroxyl-3-methoxylbenzaldehyde and 1,3-propanediol in the presence of DMF-DMS adduct and characterized by IR spectrum, UV-Vis spectrum and X-ray crystallography. The title compound belongs to monoclinic, space group P21 with a = 9.8967(10), b = 8.2240(9), c = 13.3654(14) A^°, β= 90.016(2)°, C11H14O4, Mr = 210.22, V = 1087.8(2)A^°3, Z = 4, Dc = 1.284 Mg/m^3, F(000) = 448,μ = 0.098 mm^-1, the final R = 0.0300 and wR = 0.0761 for 2070 observed reflections with I 〉 2σ(I). The molecules are connected via intermolecular O-H…O hydrogen bonds into a 2D network structure. Moreover, theoretical investigations of the title compound with HF/6-31G(d) method were performed, and its stability, frontier molecular orbital composition and Mulliken charge distribution were also discussed. The compound is a bis-molecule. The two molecules stay together and could not be separated. Two crystallographically independent molecules exist in an asymmetric unit. The bond lengths and bond angles of the two molecules are slightly different with each other. 展开更多
关键词 [2-(2 6-dioxacyclohexyl)-5-methoxylphenols]2 crystal structure hydrogen bonds theoretical calculation
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Electronic Absorption Spectra and Third-Order Nonlinear Optical Property of Dinaphtho[2,3-b:2’,3’-d]Thiophene-5,7,12,13- Tetraone (DNTTRA) and Its Phenyldiazenyl Derivatives: DFT Calculations 被引量:1
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作者 Ziran Chen Yujin Zhang +3 位作者 Zhanrong He Yonghua Guan Yuan Li Hongping Li 《Computational Chemistry》 2020年第4期43-60,共18页
Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of... Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained. 展开更多
关键词 AZOBENZENE Dinaphtho[2 3-b:2 3’-d]Thiophene-5 7 12 13-Tetraone Density Functional Theory Electronic Absorption Spectra Third-Order Nonlinear Optical Property
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MgO-decorated carbon nanotubes for CO_2 adsorption:first principles calculations
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作者 朱峰 董珊 承刚 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第7期362-366,共5页
The global greenhouse effect makes it urgent to deal with the increasing greenhouse gases. In this paper the performance of MgO-decorated carbon nanotubes for CO2 adsorption is investigated through first principles ca... The global greenhouse effect makes it urgent to deal with the increasing greenhouse gases. In this paper the performance of MgO-decorated carbon nanotubes for CO2 adsorption is investigated through first principles calculations. The results show that the MgO-decorated carbon nanotubes can adsorb CO2 well and are relatively insensitive to O2 and N2 at the same time. The binding energy arrives at 1.18 eV for the single-MgO-decorated carbon nanotube adsorbing one CO2 molecule, while the corresponding values for O2 and N2 are 0.55 eV and 0.06 eV, respectively. In addition, multi-molecule adsorption is also proved to be very satisfactory. These results indicate that MgO-decorated carbon nanotubes have great potential applications in industrial and environmental processes. 展开更多
关键词 carbon nanotube CO2 adsorption first principles calculations
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自旋-轨道耦合对双层钙钛矿Ba_(2)CoOsO_(6)电磁性质的影响
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作者 李洪苹 孙安 +1 位作者 张瑶明 郭宝昌 《江苏大学学报(自然科学版)》 CAS 北大核心 2024年第6期739-744,共6页
采用第一性原理计算方法,研究了双层钙钛矿氧化物Ba_(2)CoOsO_(6)的晶体结构、电子结构及自旋-轨道耦合作用(SOC)对其电磁性质的影响,并分析电子结构和自旋-轨道耦合作用对其宏观物理性质的影响.结果表明:Ba_(2)CoOsO_(6)为反铁磁窄带... 采用第一性原理计算方法,研究了双层钙钛矿氧化物Ba_(2)CoOsO_(6)的晶体结构、电子结构及自旋-轨道耦合作用(SOC)对其电磁性质的影响,并分析电子结构和自旋-轨道耦合作用对其宏观物理性质的影响.结果表明:Ba_(2)CoOsO_(6)为反铁磁窄带隙半导体,存在Os1/Co1反位缺陷;电子结构的分析结果证实了Ba_(2)CoOsO_(6)的电荷分布为Ba_(2)^(2+)Co^(2+)Os^(6+)O_(6)^(2-),确定了2价Co离子和6价Os离子的存在;SOC的存在减小了Co离子和Os离子的自旋磁矩,同时减小了带隙;根据第一性原理计算结果可知,自旋-轨道耦合作用对电子结构和电磁性质的影响不可忽视,相较于其他方法,该方法计算值与试验分析结果更接近,也验证了理论计算的准确性. 展开更多
关键词 Ba_(2)CoOsO_(6) 双层钙钛矿 自旋-轨道耦合 第一性原理计算 反铁磁耦合 半导体
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不同地质体中CO_(2)封存研究进展 被引量:3
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作者 包琦 叶航 +1 位作者 刘琦 张敏 《低碳化学与化工》 CAS 北大核心 2024年第3期87-96,共10页
碳捕集、利用与封存(CCUS)技术是降低二氧化碳(CO_(2))排放、缓解气候变化问题的重要措施。作为CCUS技术的重要组成部分,CO_(2)地质封存是我国能源工业领域实现碳中和目标的“兜底”技术。常见的CO_(2)封存地质体包括深部咸水层、枯竭... 碳捕集、利用与封存(CCUS)技术是降低二氧化碳(CO_(2))排放、缓解气候变化问题的重要措施。作为CCUS技术的重要组成部分,CO_(2)地质封存是我国能源工业领域实现碳中和目标的“兜底”技术。常见的CO_(2)封存地质体包括深部咸水层、枯竭油气藏、深部不可采煤层和玄武岩等,不同地质体中CO_(2)的封存过程及其机理存在差异。综述了不同地质体中的CO_(2)封存机理、国际国内CO_(2)封存的主要工程实例以及不同地质体中CO_(2)封存潜力的计算方法,并对CO_(2)地质封存的前景进行了展望。 展开更多
关键词 CO_(2)地质封存 CO_(2)封存机理 地质封存项目 封存潜力计算
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CeO_(2)催化CO_(2)与甲醇合成碳酸二甲酯
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作者 李建国 贾爱忠 +2 位作者 薛伟 赵新强 王延吉 《化学工程》 CSCD 北大核心 2024年第1期54-58,共5页
针对CO_(2)和甲醇绿色合成碳酸二甲酯路线进行热力学计算分析。在反应压力0.1—8.0 MPa和反应温度293.15—473.15 K分别研究反应温度和反应压力对吉布斯自由能Δ_(r)G、平衡常数K和平衡转化率C的影响。在此基础上,以CeO_(2)为催化剂分... 针对CO_(2)和甲醇绿色合成碳酸二甲酯路线进行热力学计算分析。在反应压力0.1—8.0 MPa和反应温度293.15—473.15 K分别研究反应温度和反应压力对吉布斯自由能Δ_(r)G、平衡常数K和平衡转化率C的影响。在此基础上,以CeO_(2)为催化剂分别固定反应压力8.0 MPa或反应温度413.15 K,在不同反应温度或压力下进行反应,并将实验结果与热力学计算结果进行对比。结果表明:CeO_(2)在反应温度为373.15—473.15 K内表现出良好的催化性能,增大反应压力可以有效降低Δ_(r)G,并提高K和C,促进反应正向进行。此外,热力学计算结果显示,较低温度不同反应压力条件下,增加反应压力对反应平衡常数的增大更显著,且为开发高活性催化材料在较低温下催化CO_(2)和甲醇高效合成碳酸二甲酯提供理论参考。 展开更多
关键词 热力学计算 碳酸二甲酯 CO_(2) 甲醇 CeO_(2)
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Maximum Overlap Symmetry Molecular Orbital Calculation under CNDO/2 Approximation 被引量:4
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作者 叶世勇 湛昌国 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 1994年第2期131-138,共8页
A basic calculation procedure for the MOSMO method under CNDO/2 approximation is presented in this paper,and performed by using the same parameters as those used in the ordinary CNDO/2 LCAO-MO calculation.The calculat... A basic calculation procedure for the MOSMO method under CNDO/2 approximation is presented in this paper,and performed by using the same parameters as those used in the ordinary CNDO/2 LCAO-MO calculation.The calculated results on the whole are close to those obtained by use of the ordinary CNDO/2 LCAO-MO calculation,illustrating that the presented procedure is reasonable.Due to its simplicity,the presented calculation procedure may be feasible even in very large molecular s ystems. 展开更多
关键词 maximum overlap symmetry molecular orbital molecular orbital calculation method CNDO/2 approximation semi-empirical molecular orbital method.
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4d金属掺杂MoS_(2)改善对NO_(2)传感性能的机理研究
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作者 潘一翠 罗磊 +4 位作者 高鑫 付岳 牟芷瑶 朱洪强 冯庆 《原子与分子物理学报》 CAS 北大核心 2025年第2期175-181,共7页
二硫化钼(MoS_(2))是一种热门的气体传感器材料.针对MoS_(2)与气体分子之间的弱相互作用问题,掺杂是一种有效的解决方式.本文利用基于密度泛函理论(DFT)的第一性原理平面波超软赝势计算方法,对二氧化氮(NO_(2))分子在4d金属掺杂后的MoS_... 二硫化钼(MoS_(2))是一种热门的气体传感器材料.针对MoS_(2)与气体分子之间的弱相互作用问题,掺杂是一种有效的解决方式.本文利用基于密度泛函理论(DFT)的第一性原理平面波超软赝势计算方法,对二氧化氮(NO_(2))分子在4d金属掺杂后的MoS_(2)表面上吸附的微观机制进行了理论研究.研究结果表明:4d过渡金属元素掺杂有利于提高MoS_(2)吸附NO_(2)后的稳定性,且掺杂改变了材料表面的还原性,改善了其传感性能.掺入4d金属原子的材料禁带宽度显著减小,并且在费米能级附近形成了新的杂质峰,这大大提升了它的导电性.且掺杂原子的4d与5s轨道电子之间的协同作用会提升气体分子与材料之间的传感特性,这表明4d金属原子掺入MoS_(2)可以成为一种有效的NO_(2)传感器材料.本文的工作有助于寻求合适的化学掺杂的方法来提高MoS_(2)基气体传感器的性能. 展开更多
关键词 MoS_(2) NO_(2) 吸附 掺杂 第一性原理计算
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非热等离子体强化Cu催化CO_(2)加氢制甲醇机理探索
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作者 陈玉民 董永恒 +5 位作者 史承静 孙龙坤 朱丙鑫 李冰 刘洋 周怀春 《煤炭学报》 EI CAS CSCD 北大核心 2024年第10期4276-4294,共19页
CO_(2)耦合绿氢制甲醇可同时实现CO_(2)规模转化利用和绿氢储存,甲醇可作为绿色低碳燃料或工业平台产品大规模应用,对推动碳捕集、利用与封存(CCUS)技术进一步发展具有重要意义。非热等离子体(NTP)能在温和条件下活化CO_(2)进行加氢反应... CO_(2)耦合绿氢制甲醇可同时实现CO_(2)规模转化利用和绿氢储存,甲醇可作为绿色低碳燃料或工业平台产品大规模应用,对推动碳捕集、利用与封存(CCUS)技术进一步发展具有重要意义。非热等离子体(NTP)能在温和条件下活化CO_(2)进行加氢反应,耦合催化剂后可实现甲醇等特定产物定向调控,但其反应机理亟待明确。基于此,结合介质阻挡放电(DBD)实验与连续脉冲等离子体反应动力学模拟,对NTP强化Cu/γ-Al_(2)O_(3)催化CO_(2)加氢制甲醇反应机理和过程耦合规律进行研究。实验证明,NTP与10%Cu/γ-Al_(2)O_(3)耦合可在80℃、0.1 MPa下实现18.74%CO_(2)转化率和36.28%CH_(3)OH选择性。放电参数在线监测和原位发射光谱(OES)测量结果表明,耦合Cu/γ-Al_(2)O_(3)后局部放电增强,使得平均电子能量和密度增加促进CO、H生成并参与表面反应而消耗,导致光谱强度减弱。进一步由敏感性和ROP分析发现,NTP中H、CO等活性物质通过CO_(2)(S)+H→COOH(S)、CO+H(S)→HCO(S)、CO(S)+H→HCO(S)、CH_(3)O(S)+H→CH_(3)OH(S)等E-R反应替代对应高能垒L-H反应促进甲醇高效生成。分析反应路径得出,甲酸盐(HCOO*)路径是Cu/γ-Al_(2)O_(3)表面甲醇生成主要路径,其中反应CH_(3)O(S)+H(S)→CH_(3)OH(S)+Cu(S)是最大限速步,RWGS+CO氢化路径中通过CO_(2)(S)→COOH(S)→CO(S)路线生成CO(S)并快速脱附为降低CH_(3)OH选择性重要因素。不确定性分析表明,虽然提高CO_(2)吸附速率可有效提高其转化率,但当H(S)不足时反而会增加CO选择性,最优CO_(2)和H_(2)吸附速率比为γ(H_(2))/γ(CO_(2))=7~8;提高CO(S)吸附稳定性并增强H_(2)电子碰撞解离以促进H生成,可提高CO(S)→HCO(S)、CH_(3)O(S)→CH_(3)OH(S)等速率,协同实现27.4%、51%的CO_(2)转化率和CH_(3)OH选择性。 展开更多
关键词 等离子体催化 CO_(2)加氢 绿色甲醇 动力学计算 发射光谱
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