Spin gapless armchair graphene nanoribbons under magnetic field and uniaxial strain

Using Green＇s function method, we investigate the spin transport properties of armchair graphene nanoribbons （AG- NRs） under magnetic field and uniaxial strain. Our results show that it is very difficult to transform narrow AGNRs directly from semiconductor to spin gapless semiconductors （SGS） by applying magnetic fields. However, as a uniaxial strain is exerted on the nanoribbons, the AGNRs can transform to SGS by a small magnetic field. The combination mode be- tween magnetic field and uniaxial strain displays a nonmonotonic arch-pattern relationship. In addition, we find that the combination mode is associated with the widths of nanoribbons, which exhibits group behaviors.     

提升教师信息化教学能力的教改措施与实施效果评估

本文旨在提出一些策略和措施帮助教师提升信息化教学能力,以适应数字化时代的教育需求。通过文献综述和实证研究,本文确定了教师信息化教学能力的要素和重要性,并提出了提升策略,包括教师培训与支持、学校基础设施与技术支持、教学设计与创新等;同时,讨论了评估与反馈机制的建立,以确保教师信息化教学能力提升的有效性和可持续性。研究分析表明,有效的教改措施能显著提升教师信息化教学能力,促进学生学习成绩的提高和学习兴趣的增强。本研究可为教育部门、学校管理者和教师提供指导,促进教育教学的创新和提升,培养具备创新思维和终身学习能力的学生。     

新生儿重症监护病房呼吸机相关性肺炎病原学分析

目的探讨新生儿重症监护病房（NICU）呼吸机相关性肺炎（VAP）病原菌特点及药敏情况,为临床治疗VAP提供科学依据。方法对2008年1月-2010年6月本院NICU102例VAP病例进行深部痰培养,对其病原菌分布及药敏进行分析。结果102例VAP患者中86例痰培养阳性,其中革兰氏阴性菌73例（82．95％）,对β-内酰胺类抗菌素普遍耐药,对丁胺卡那中度敏感,对亚胺培南、环丙沙星敏感。革兰氏阳性球菌13例（14．77％）,对青霉素、红霉素均耐药,对头孢菌素类抗菌素普遍耐药,对环丙沙星中度敏感,对万古霉素敏感。真菌2例,对氟康唑敏感。结论NICU中VAP病原菌以革兰氏阴性菌为主,其次为革兰氏阳性球菌,两者均对常用抗菌素如头孢菌素类等普遍耐药;大部分革兰氏阴性菌对亚胺培南敏感,革兰氏阳性球菌对万古霉素敏感。     

Magnetotransport in a dual waveguide coupled by a finite barrier： Energy filter and directional coupler

We propose in this paper that a dual waveguide coupled by a finite barrier be able to serve as an energy filter under a perpendicular magnetic field. In the waveguide direction, the conductance exhibits a periodic square-wave pattern in which the miniband is controlled by the magnetic and potential modulation. The electrons with energies in the miniband can completely transfer along one waveguide while the other electrons undergo filtration. Compared with the coupled waveguide without magnetic modulation, the structure under magnetic field is found to be a good directional coupler. By adjusting the potential barrier and magnetic field, the electrons input from one port of waveguide can transfer to any other ports.     

Thermal transport in twisted few-layer graphene

Twisted graphene possesses unique electronic properties and applications, which have been studied extensively. Recently, the phonon properties of twisted graphene have received a great deal of attention. To the best of our knowledge,thermal transports in twisted graphene have been investigated little to date. Here, we study perpendicular and parallel transports in twisted few-layer graphene(T-FLG). It is found that perpendicular and parallel transports are both sensitive to the rotation angle θ between layers. When θ increases from 0° to 60°, perpendicular thermal conductivity κ_(||) first decreases and then increases, and the transition angle is θ = 30°. For the parallel transport, the relation between thermal conductivity κand θ is complicated, because intra-layer thermal transport is more sensitive to the edge of layer than their stacking forms. However, the dependence of interlayer scattering on θ is similar to that of κ⊥. In addition, the effect of layer number on the thermal transport is discussed. Our results may provide references for designing the devices of thermal insulation and thermal management based on graphene.     

Spin-polarized transport in graphene nanoribbon superlattices

By the Green’s function method,we investigate spin transport properties of a zigzag graphene nanoribbon superlattice(ZGNS) under a ferromagnetic insulator and edge effect.The exchange splitting induced by the ferromagnetic insulator eliminates the spin degeneracy,which leads to spin-polarized transport in structure.Spin-dependent minibands and minigaps are exhibited in the conductance profile near the Fermi energy.The location and width of the miniband are associated with the geometry of the ZGNS.In the optimal structure,the spin-up and spin-down minibands can be separated completely near the Fermi energy.Therefore,a wide,perfect spin polarization with clear stepwise pattern is observed,i.e.,the perfect spin-polarized transport can be tuned from spin up to spin down by varying the electron energy.     

嵌入线型缺陷的石墨纳米带的热输运性质

采用非平衡格林函数方法研究了嵌入有限长、半无限长、 无限长线型缺陷的锯齿型石墨纳米带 (ZGNR)的热输运性质.结果表明, 缺陷类型和缺陷长度对ZGNR的热导有重要影响. 当嵌入的线型缺陷长度相同时, 包含t5t7线型缺陷的石墨纳米带比包含Stone-Wales线型缺陷的条带热导低. 对于嵌入有限长、同种缺陷的ZGNR, 其热导随线型缺陷的长度增加而降低, 但是当线型缺陷很长时, 其热导对缺陷长度的变化不再敏感.通过比较嵌入有限长、半无限长、无限长线型缺陷的ZGNR, 我们发现嵌入无限长缺陷的条带比嵌入半无限长缺陷的条带热导高, 而后者比嵌入有限长线型缺陷的条带热导高. 这主要是因为在这几种结构中声子传输方向的散射界面数不同所导致的. 散射界面越多, 对应的热导就越低. 通过分析透射曲线和声子局域态密度图, 解释了这些热输运现象. 这些研究结果表明线型缺陷能够有效地调控石墨纳米带的热输运性质. 关键词： 石墨烯 线型缺陷 热导     

Nonideal effects in quantum field-effect directional coupler

The nonideal effects in a quantum field-effect directional coupler where two quantum wires are coupled through a finite potential barrier are studied by adopting the lattice Green function method. The results show that the electron energy distribution, asymmetric geometry and finite temperature all have obvious influence on the electron transfer of the coupler. Only for the electrons with energies in a certain region, can the complete periodic transfer between two quantum wires take place. The conductance of these electrons as a function of the barrier length and potential height exhibits a fine periodic or quasi-periodic pattern. For the electrons with energies beyond the region, however, the complete periodic transfer does not hold any more since many irregular oscillations are superimposed on the conductance profile. In addition, the finite temperature and asymmetric geometry both can reduce the electron transfer efficiency.     

区域性危重新生儿院前转运网络的意义与实践

目的讨论危重新生儿院前转运网络的意义。方法建立以我院新生儿监护中心（NICU）为网络中心,以郴州市及周边地区共41家基层医院为成员单位的区域性危重新生儿院前转运网络系统,对危重新生儿进行转运,对转运新生儿例数、病种分布、愈后等临床资料进行分析。结果3年来转运1003例新生儿,转运新生儿逐年增加（P〈0.05）,转运后放弃63例,死亡70例,死亡率逐年降低（P〈0.05）。300例转运新生儿进行了转运前新生儿危重病例评分,其中非危重组68例,无死亡;危重组182例,死亡10例,死亡率5.49%;极危重组50例,死亡8例,死亡率16%。评分病情越重,病死率越高,差异有统计学意义（P〈0.05）。结论建立完善的院前转运网络系统,掌握转运指征和及时转运,对保证危重新生儿转运救治成功率,提高其日后的生存质量优化本地区人口结构有着十分重要的意义。     

Robust and intrinsic type-III nodal points in a diamond-like lattice

An ideal type-III nodal point is generated by crossing a completely flat band and a dispersive band along a certain momentum direction. To date, the type-III nodal points found in two-dimensional (2D) materials have been mostly accidental and random rather than ideal cases, and no one mentions what kind of lattice can produce ideal nodal points. Here, we propose that ideal type-III nodal points can be obtained in a diamond-like lattice. The flat bands in the lattice originate from destructive interference of wavefunctions, and thus are intrinsic and robust. Moreover, the specific lattice can be realized in some 2D carbon networks, such as T-graphene and its derivatives. All the carbon structures possess type-III Dirac points. In two of the structures, consisting of triangular carbon rings, the type-III Dirac points are located just on the Fermi level and the Fermi surface is very clean. Our research not only opens a door to finding the ideal type-III Dirac points, but also provides 2D materials for exploring their physical properties experimentally.