Ab – initio restricted Hartree - Fock method within the framework of large unit cell (LUC) formalism is used to investigate the electronic structure of Si and Ge nanocrystals. The surface and core properties are investigated. A large unit cell of 8 atoms is used in the present analysis. Cohesive energy, energy gap, conduction and valence band widths are obtained from the electronic structure calculations. The results are compared with available experimental data and theoretical results of other investigators. The calculated lattice constant is found to be slightly larger than the corresponding experimental value because we use only 8 atoms and we compared the results with that of the bulk crystals, nanoclusters are expected to have stronger directional bonds that in their bulk structure. The surface states are found to be mostly non-degenerated because of the effect of surface discontinuity and the existence of oxygen atoms. Valence and conduction bands are found to be wider on the surface due to the splitting of energy levels due to the existence of oxygen atoms. The present method can be used to investigate the electronic structure of bulk, surface and nanocrystals.
Single mode-no core-single mode fiber structure with a section of tuned no-core fiber diameter to sense changes in relative humidity has been experimentally demonstrated. The sensor performance with tuned NCF diameter was investigated to maximize the evanescent fields. Different tuned diameters of of (100, 80, and 60)μm were obtained by chemical etching process based on hydrofluoric acid immersion. The highest wavelength sensitivity was obtained 184.57 pm/RH% in the RH range of 30% –100% when the no-core fiber diameter diameter was 60 μm and the sensor response was in real-time measurements
(14)
(15)
What concerns the research is employing the modern technology in a compatible way, because it has multiplied with the visual working functions and has grown in a special way with the development of the digital graphic design field which represents a crystallization product according to investigation and experimentation mechanism within the field of the scientific research in the design field and development of the skills of the first designing worker, who always seeks to find working and functional structures in order to produce a design with a clear meaning by utilizing the technological abilities including the acoustic tech
... Show More
(1)
Positron annihilation lifetime (PAL) technique has been employed to
study the microstructural changes of polyurethane (PU), EUXIT 101
and epoxy risen (EP), EUXIT 60 by Gamma-ray irradiation with the
dose range (95.76 - 957.6) kGy. The size of the free volume hole and
their fraction in PU and EP were determined from ortho-positronium
lifetime component and its intensity in the measured lifetime spectra.
The results show that the irradiation causes significant changes in the
free volume hole size (Vh) and the fractional free volume (Fh), and
thereby the microstructure of PU and EP. The results indicate that
the γ-dose increases the crystallinity in the amorphous regions of PU
and increas
(1)
Here we determined the structure of a cold active family IV esterase (EstN7) cloned
(16)
The term of heterocyclic chemistry focuses only on heterocyclic compounds, which consider as a percentage of organic chemistry, they equal to greater than sixty-five. These compounds are widely founded in nature and most of them are important to life. In the past few years, scientist fused on 1,2,4-triazoles and their condensed heterocyclic ring due to their medicinal significance, 1,2,4-triazole containing Sulphur atom is one of the important heterocyclic moieties due to its broad range of biological activities also their derivatives can accommodate one of the alternatives as electronic effect as exchanges of the electronic density (electron donating or withdrawing) groups ; for all what mentioned above they are consider as a core
... Show More
(3)
(1)
The Research examines the transmission advantage from Floor Trading (FT) to the Electronic Trading (ET) in the Iraqi Stock Exchange (ISE). Testing three hypothesis, first, test the significant different of market depth before and after period of ET used, second, test the significant different of market liquidity also before and after period of ET used. And third test the impact of market depth and liquidity on the performance of ISE. AnEvent Study is depended with 74 observing distributed equality on research period which is extent among 2006 to 2012, Note that the event window is 5-7-2009.The Result of hypothesis testing explore that the all three null main hypothesis is refusing and accept the alternative of it's because the ET
... Show More
Abstract
Leadership has now become a process for applying methods and techniques that make the Organization at the top of its competitive pyramid a greater market share. Leadership has become a focus for all leaders and managers، and leaders and managers are increasingly seeking to develop their skills and leadership skills. The research started with a clear problem of specific questions to ensure that the general objective of the research is to describe the characteristics of the leader and to clarify the dimensions of empowering the workers and to highlight the role of the leader in empowering the workers. The study examines the relation between the role of the leader in
... Show More
(36)