吸附缺陷对armchair型石墨烯纳米条带输运性质的影响

本文基于第一性原理研究了单个氢原子吸附缺陷对armchair型石墨烯纳米条带电子输运性质的影响。研究发现,吸附缺陷使armchair型石墨烯纳米条带在费米面附近的导电性有所降低,但透射能隙依然存在。缺陷对透射抑制的强弱与其吸附位置有关。在完整石墨烯纳米条带的布洛赫波函数分布几率较大处引入缺陷对电子输运的阻碍作用较大。对于布洛赫波函数分布相同的情况,吸附位置越靠近石墨烯纳米条带中心,则对电子输运的阻碍作用越大。

清代宫廷交椅鉴赏

交椅由胡床演变而来,是古人精湛工艺及文化思想的集合体,因其便携性,促使我国古代起居方式变得更为灵活多样,特别是在行军、出游等活动中。自宋代以来,交椅在营事活动中逐渐发展成为身份地位的象征,其装饰外观受礼制约束。本文通过梳理不同朝代相关交椅的古籍、绘画等资料,以故宫博物院馆藏3把清代交椅实物为例,进行鉴赏及历史文化挖掘,解读交椅在装饰中的制度性、实用性与艺术性,以期让交椅的设计者与使用者更好地了解其所承载的文化内涵。

丹麦木质扶手椅家具的形态特征

丹麦家具在现代家具的发展中具有重要地位,独特的造型与实用性对现代家具影响深远。为探究丹麦木质扶手椅家具的形态特征,将扶手椅按照部件分为靠背、扶手、座面和腿足4个部分,采用图例分析法和归纳法,分析4个部件的形态特征,归纳总结出丹麦扶手椅家具整体形态的变化多为线条的粗细弯曲,靠背部件种类丰富,扶手和腿足部件有圆材和方材,座面形态变化不大,主要体现材质变化的特点。进一步完善了丹麦家具的研究体系,丰富了丹麦家具形态研究的相关理论。丹麦家具的形态特征对现代家具有巨大的影响,值得深入探究并为现代家具的发展提供参考。

极简主义思潮驱动下的扶手椅优化设计

“极简”是一种以简约为中心,以“极简”为中心的人生哲学与设计概念,以“最本质”为中心,以“内涵”为中心,它的哲学始终是革新的先导,极简主义的理念挑战了传统的奢华和浮华,提倡以简单、清晰和实用为价值基准,在设计领域中致力于在外观和功能上兼备。本文旨在基于极简主义的艺术理念,根据极简主义的基本特征,对扶手椅设计进行创新,实现艺术与技术的统一,达到功能、情感与文化的融合。本文方法主要是通过定性研究对极简主义内涵进行整理,并对极简主义的应用案例进行分析了解其现状,主要是以市场上售卖热门的极简主义扶手椅及宜家品牌的椅子进行调研。最后,通过市场调研等方式,了解大众的设计需求,进行极简主义的扶手椅的优化设计,完成设计实践。

Armchair型氮化硼纳米管的Kekule结构计数

介绍了带半-B12N12帽的armchair型单壁氮化硼纳米管(BN-SWNT),并对其Kekule结构的个数进行了计算.通过使用定位配置技术和特殊的编码方法,建立了关于Kekule计数K的递推公式.数值计算结果表明,与zigzag型类似,armchair型氮化硼纳米管的Kekule计数也随着管子中间层数的增加呈指数增长.

Defect engineering on the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons

We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons(APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density functional calculations. It is found that the atomic vacancies are easier to form and detain at the edge region rather than a random distribution through analyzing formation energy and diffusion barrier. The highly local defect states are generated at the vicinity of the Fermi level, and emerge a deep-to-shallow transformation as the width increases after introducing vacancies in APNRs.Moreover, the electrical transport of APNRs with vacancies is enhanced compared to that of the perfect counterparts. Our results provide a theoretical guidance for the further research and applications of PNRs through defect engineering.

The complex band structure for armchair graphene nanoribbons

Using a tight binding transfer matrix method, we calculate the complex band structure of armchair graphene nanoribbons. The real part of the complex band structure calculated by the transfer matrix method fits well with the bulk band structure calculated by a Hermitian matrix. The complex band structure gives extra information on carrier＇s decay behaviour. The imaginary loop connects the conduction and valence band, and can profoundly affect the characteristics of nanoscale electronic device made with graphene nanoribbons. In this work, the complex band structure calculation includes not only the first nearest neighbour interaction, but also the effects of edge bond relaxation and the third nearest neighbour interaction. The band gap is classified into three classes. Due to the edge bond relaxation and the third nearest neighbour interaction term, it opens a band gap for N = 3M- 1. The band gap is almost unchanged for N =3M ＋ 1, but decreased for N = 3M. The maximum imaginary wave vector length provides additional information about the electrical characteristics of graphene nanoribbons, and is also classified into three classes.

Molar Binding Energy of Zigzag and Armchair Single-Walled Boron Nitride Nanotubes

Molar binding energy of the boron nitride single-walled zigzag and armchair nanotubes is calculated within the qua-si-classical approach. We find that, in the range of ultra small radii, the binding energy of nanotubes exhibit an oscil-latory dependence on tube radius. Nanotubes (1,1), (3,0), and (4,0) are predicted to be more stable species among sin-gle-walled boron nitride nanotubes. The obtained binding energies of BN single-walled nanotubes corrected with zero-point vibration energies lies within the interval (12.01-29.39) eV. In particular, molar binding energy of the ul-tra-large-radius tube is determined as 22.95 eV. The spread of the molar zero-point vibration energy of BN nanotubes itself is (0.25-0.33) eV and its limit for ultra-large-radius tubes is estimated as 0.31 eV. The binding energy peak lo-cated at 2.691 ? corresponds to the equilibrium structural parameter of all realized stable BN nanotubular structures.

Theoretical Study on the Reaction Mechanism between Dichlorocarbene and Armchair Single-walled Carbon Nanotubes

The reaction mechanism between CC12 and armchair single-walled carbon nanotubes （ASWCNTs） （3,3） and （4,4） has been studied by semiempirical AM1 and ab initio methods. The activation barriers of CC12 adding to ASWCNT （3,3） and （4,4） are computed and compared. The lower barrier of CC12 forms cycloaddition isomer on （3,3） maybe because the strain energy of （3,3） is larger than that of （4,4）. Our theoretical results are consistent with the experimental results.

Effects of edge hydrogenation and Si doping on spin-dependent electronic transport properties of armchair boron–phosphorous nanoribbons

In this article, the spin-dependent electronic and transport properties of the armchair boron–phosphorous nanoribbons（ABPNRs） are mainly studied by using the non-equilibrium Green function method combined with the spin-polarized density function theory. Our calculated electronic structures indicate that the edge hydrogenated ABPNRs exhibit a ferromagnetic bipolar magnetic semiconductor property, and that the Si atom doping can make ABPNRs convert into up-spin dominated half metal. The spin-resolved transport property results show that the doped devices can realize 100% spinfiltering function, and that the interesting negative differential resistance phenomenon can be observed. Our calculations suggest that the ABPNRs can be constructed as a spin heterojunction by introducing Si doping partially, and it would be used as a spin-diode for nano-spintronics in future.

Charge susceptibilities of armchair graphene nanoribbon in the presence of magnetic field

We present the behaviors of both dynamical and static charge susceptibilities of undoped armchair graphene nanoribbon using the Green＇s function approach in the context of tight binding model Hamiltonian.Specifically,the effects of magnetic field on the the plasmon modes of armchair graphene nanoribbon are investigated via calculating the correlation function of charge density operators.Our results show that the increase of magnetic field makes the high-frequency plasmon mode for both metallic and insulating cases disappear.We also show that low-frequency plasmon mode for metallic nanoribbon appears due to increase of magnetic field.Furthermore,the number of collective excitation modes increases with ribbon width at zero magnetic field.Finally,the temperature dependence of the static charge structure factor of armchair graphene nanoribbon is studied.The effects of both magnetic field and ribbon width on the static charge structure factor are discussed in detail.

Charge structure factors of doped armchair nanotubes in the presence of electron-phonon interaction

We present the behaviors of both dynamical and static charge susceptibilities of doped armchair nanotubes using the Green function approach in the context of Holstein-model Hamiltonian.Specially,the effects of magnetization and gap parameter on the the plasmon modes of armchair nanotube are investigated via calculating correlation function of charge density operators.Random phase approximation has been implemented to find the interacting dynamical charge susceptibility.The electrons in this systems interacts with each other by mediation of dispersionless Holstein phonons.Our results show that the increase of gap parameter leads to decreasing intensity of charge collective mode.Also the frequency position of the collective mode tends to higher frequencies due to the gap parameter.Furthermore the number of collective excitation mode decreases with chemical potential in the presence of electron-phonon interaction.Finally the temperature dependence of static charge structure factor of armchair nanotubes is studied.The effects of the gap parameter,magnetization and electron-phonon interaction on the static structure factor are addressed in details.

Spin-dependent transport characteristics of nanostructures based on armchair arsenene nanoribbons

By employing non-equilibrium Green＇s function combined with the spin-polarized density-functional theory, we investigate the spin-dependent electronic transport properties of armchair arsenene nanoribbons（a As NRs）. Our results show that the spin-metal and spin-semiconductor properties can be observed in a As NRs with different widths. We also find that there is nearly 100% bipolar spin-filtering behavior in the a As NR-based device with antiparallel spin configuration. Moreover, rectifying behavior and giant magnetoresistance are found in the device. The corresponding physical analyses have been given.

Electronic transport for armchair graphene nanoribbons with a potential barrier

This paper studies the electronic transport property through a square potential barrier in armchair-edge graphene nanoribbon （AGNR）. Using the Dirac equation with the continuity condition for wave functions at the interfaces between regions with and without a barrier, we calculate the mode-dependent transmission probability for both semiconducting and metallic AGNRs, respectively. It is shown that, by some numerical examples, the transmission probability is generally an oscillating function of the height and range of the barrier for both types of AGNRs. The main difference between the two types of systems is that the magnitude of oscillation for the semiconducting AGNR is larger than that for the metallic one. This fact implies that the electronic transport property for AGNRs depends sensitively on their widths and edge details due to the Dirac nature of fermions in the system.

Electronic Transport Properties of Diblock Co-Oligomer Molecule Devices Sandwiched between Nitrogen Doping Armchair Graphene Nanoribbon Electrodes

We investigate the electronic transport properties of dipyrimidinyl-diphenyl sandwiched between two armchair graphene nanoribbon electrodes using the nonequilibrium Green function formalism combined with a first-principles method based on density functional theory. Among the three models M1–M3, M1 is not doped with a heteroatom. In the left parts of M2 and M3, nitrogen atoms are doped at two edges of the nanoribbon. In the right parts, nitrogen atoms are doped at one center and at the edges of M2 and M3, respectively. Comparisons of M1, M2 and M3 show obvious rectifying characteristics, and the maximum rectification ratios are up to 42.9 in M2. The results show that the rectifying behavior is strongly dependent on the doping position of electrodes. A higher rectification ratio can be found in the dipyrimidinyl-diphenyl molecular device with asymmetric doping of left and right electrodes, which suggests that this system has a broader application in future logic and memory devices.

柳木圈椅技艺及其传承创新研究

对柳木圈椅技艺及其传承创新进行研究。通过分析柳木圈椅在选材用材、工艺技术、造型艺术等方面的造物方法,提炼出柳木圈椅优秀的技艺特征。选取十多件不同地域代表性柳木圈椅为重点研究对象,通过分析柳木圈椅的造型、材料、制作、传承方式等在时代发展面前的不适,指出柳木圈椅目前存在的问题及优秀技艺濒临失传的原因。从系统资料的挖掘整理、借助基地培养传承人、借助平台打造品牌等方面,提出柳木圈椅传承路径;从设计创新、材料选用与工艺的创新等方面,提出具体的可行性创新策略,并附以设计实践案例,为传统手工艺的传承与创新发展提供借鉴。

The First Principle Study on C-doped Armchair Boron Nitride Nanoribbon Rectifier

The electronic transport properties of armchair-edged boron nitride nanoribbons（ABNNRs） devices were investigated by the first principle calculations. The calculated results show that the ABNNR device doped with carbon atoms in one of the electrodes acts as a high performance nanoribbon rectifier. It is interesting to find that there exists a particular bias-polarity-dependent matching band between two electrodes,leading to a similar current-voltage（I-V） behavior as conventional P-N diodes. The I-V behavior presents a linear positive-bias I-V characteristic,an absolutely negligible leakage current,and a stable rectifying property under a large bias region. The results suggest that C doping might be an effective way to raise ABNNRs devices＇ rectifying performance.

Lesson 2 Armchair Strategists

Lesson 2 Armchair Strategists HAOJIE(1)小李看过不少有关游泳的书,他总是告诉别人应该如何,可是他从来没下过水,这种人大概只会“纸上谈兵”Translation Xiao Li hasreadmany books on swimmin…

电场和应力作用下氮钝化扶手型氧化锌纳米带的电子结构和磁特性

采用密度泛函理论(DFT)方法,在LDA+U水平下详细研究了电场和应力作用下氮钝化扶手型氧化锌纳米带(NA8-ZnONRs)的电子结构和磁特性。对体系的电子结构和磁性进行详细的计算,结果表明:本征扶手型氧化锌纳米带(A8-ZnONRs)是无磁性P型半导体。氮钝化后NA8-ZnONRs具有铁磁金属性,其磁性主要来源于N2p轨道(2.56μ_(B))和O2p轨道(0.69μ_(B))电子的自旋极化,总磁矩为3.21μB。NA8-ZnONRs体系对X方向电场有较强的响应,通过调节X方向电场的幅度,可以有效调节体系的磁矩。在X方向电场作用下体系仍具有铁磁金属性,磁性也主要来源于N2p和O2p轨道电子的自旋极化。施加X方向应力作用后,体系仍表现为铁磁金属性。与NA8-ZnONRs纳米带磁矩相比,体系的总磁矩均发生了较大幅度的增长,表明体系对应力作用具有较明显的相应。但随着应力幅度的调节,总磁矩的变化较平坦。表明施加应力可以有效调节体系的磁矩,但在较小应力范围内,体系对应力变化的相应不明显。

中国传统圈椅的制作工艺研究

研究木工工具与榫卯结构之间的关系有利于传统家具的修复。本文采取案例分析法,以典型的明式框架圈椅为例,将制作技艺分为部件加工前的准备工序、部件加工时的处理工序和部件加工后的修整工序,并将圈椅拆分为上、中、下三个部分进行结构解析,以不同工序中所使用的工具为重点,对各零部件的制作进行介绍。通过对制作工序的梳理,将木工工具分为量划工具、解斫工具、穿剔工具、平木工具以及其他辅助工具。针对不同形态的造型、不同的榫卯连接方式,部件加工时的工具选择也有所不同。