By employing the theoretical method based on tight-binding, we study electronic band structure of single-wall carbon nanotube (CNT) superlattices, which the system is the made of the junction between the zigzag and armchair carbon nanotubes. Exactly at the place of connection, it is appeared the pentagon–heptagon pairs as topological defect in carbon hexagonal network. The calculations are based on the tight binding model in the nearest-neighbor approximation. We seek to describe electronic band structure in the presence of the pentagon-heptagon pairs. Our calculation show that the pentagon–heptagon pairs defect in the nanotube structures is not only responsible for a change in a nanotube diameter, but also governs the electronic behaviour around Fermi level. Also, we obtain the Fermi energy of the system via integration of the density of states and matching it to the number of electron in the unit cell. The numerical results may be useful to design of electronic devices based on CNTs.

Nowadays, the fundamental role of having a purpose for life in physical and mental health has been confirmed. According to victor frankl, presence of a purpose in life gives life a meaning and increases resilience against pains and traumas. The importance of the purpose in life construct reveals the need for a reliable and valid tool to measure it. Crumbaugh and Maholick's purpose in life questionnaire is the first and one of the most applied tools for the assessment of life's purposefulness. The aim of this research is to determine the factor structure of purpose in life questionnaire. The questionnaire was administered on 206 students who were selected through random stratified sampling at Ferdowsi University of Mashhad. Exploratory factor analysis showed that there are two factors "comprehension" and "purpose" and this finding were confirmed by confirmatory factor analysis. Altogether results of this research showed factor validity of the purpose in life questionnaire with a two factor pattern

The two-dimensional structure of graphene, consisting of an isotropic hexagonal lattice of carbon atoms, shows fascinating electronic properties, such as a gapless energy band and Dirac fermion behavior of electrons at fermi surface. Anisotropy can be induced in this structure by electrochemical pressure. In this article, by using tight-binding method, we review anisotropy effects in the electronic nanostructure of graphene in one direction. For this purpose, we just consider π states, which express electronic characteristics, and compare electronic band of π states with that of isotropic honeycomb lattice in graphene. As a result, by applying pressure or stretching in one direction, the gap will be created in the electronic band at the fermion surface, which can be useful for semiconducting nano devices. The isotropic graphene has a band structure with no energy gap. By applying electrochemical pressure in one direction, the translational symmetry can be broken, therefore an energy gap appears between the two bands.

In this research, we have studied the band structure, optical properties and thermal emission spectrum of 2D silicon photonic crystal with hexagonal structure. The band structure, band gap map and theb and gap size have been calculated by plane wave expansion method in terms of radius. The maximum band gap size of TE and TM polarization, and the complete gap size are 51%, 20% and 17% at air hole radii of r=0. 43a, 0. 50a and r=0. 48a, respectively. The thermal emission spectrum has been calculated by Finite Difference Time Domain (FDTD) methd and Kirchhoff's Law in the range of 1 to 10. The obtained results show that by adjusting the geometric parameters, one can engineer the band structure, and the thermal emission spectrum of 2D silicon photonic crystal can be controlled in a manner that can be used in thermophotovoltaic systems.

We report on a semiempirical tight-binding model for 3C-SiC including the effect of sp3d5s* orbitals and spin– orbit coupling (Δ ). In this work, we illustrate in detail the method to develop such a model for semiconductors with zincblende structure, based on Slater– Koster integrals, and we explain the optimization method used to fit the experimental results with such a model. This method shows high accuracy for the evaluation of 3C-SiC band diagram in terms of both the experimental energy levels at high symmetry points and the effective masses.

In this paper, a modified auto zeroed integrator is used to design and simulate a low-voltage high-Q switched capacitor pseudo 2-path filter. The filter is a sixth–order Chebyshev band-pass filter operating at sampling frequency of 1MHz and center frequency of 250 kHz with a quality factor of 50. The proposed filter has both low-voltage and high speed properties of the auto zeroed integrators and accurate center frequency of N-path band-pass filters. The operating voltage is 1.5v with no use of voltage bootstrapper circuit. Simulation is done using HSPICE and 0.25 mm CMOS technology.