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.
World statistics proved that the most of work dangerous accidents, which causes death, are occurred in the construction works. These accidents related to many causes such as loss of workers experience and ignoring rules of safety requirements, especially young workers. Due to the risk of accidents that may occur in the site of work, the idea of this study crystallized to show the relationship between the age of worker and number of injuries and accidents, to identify the causes of these injuries, and to put the appropriate solutions to avoid or reduce the risk of work injuries. Also, the research shows the main principles of safety requirements to forming a clear picture about the subject of the study. A questioner form was prepared to c
... Show MoreThe article describes a study on the role of vitamin C as a protective agent for the teeth, gum, and implants using quantum chemical calculations and polarization tests. The Density Functional Theory (DFT) at 6-311G (d, p) basis set is used to estimate the ability of vitamin C to inhibit the corrosion of the abovementioned parts. The experimental study was performed in a at human body media simulator (Hank’s balanced salt solution) at a temperature of 37°C. The compound was optimized for its ground state, physical properties, and corrosion parameters. Further, HOMO, LUMO, energy gap, dipole moment, and other parameters were used to predict the inhibitor’s efficiency. Gaussian 09, UCA-FUKUI, MGL tools, DSV, and LigPlus software was used
... Show MoreThe present study represent the histological and histochemical structure of the esophagus of laughing dove Streptopelia senegalensis, one of the wild birds, which feed on the seeds( grainvorous).The result showed that the esophagus long tubular quit wide and highly distensible organ situated at the right side of the nick , lie between pharynx and stomach it was divided into cervical and thoracic part , the cervical part longer than the thoracic part, and the crop was merely enlargement fusiform in shape which located at the entrance of the thorax. Esophagus parts showed that composed of four layer ;the mucosa, sub mucosa, muscular and adventitia or serosa, the mucosal layer was arranged in folds which was longer in the c
... Show MoreThis research aims to measure the discrepancy between the accounting income which is prepared according to generally accepted accounting principles and the tax income that is being prepared according to the rules and tax laws, and find out the most important differences that arise between incomes.The research found the most important to the following conclusions:1.Faces determining the tax base for companies subject to income challenges related to the weakness of the efficiency and the possibility of technical angel tax and its ability to examine the financial statements submitted to the tax administration tax.2.That the tax system in Iraq does not comply with accepted accounting principles generally accepted.The research recommends the
... Show MoreThe research section tagged (Aesthetics of Abstract Expressionism and its Representations in the Artistic Products of Students of the Department of Art Education) into four chapters and it included in..
The first chapter: (the methodological framework) for the research, and the research problem is summarized through the question (what are the aesthetics of abstract expressionism and its representations in the artistic productions of the students of the Department of Art Education). In the products of students of the Department of Art Education).
The aim of the research was (discovering the aesthetics of abstract expressionism and its representations in the artistic products of the students of the Department of Art Education). As we
The mechanism for selecting the President of the Republic and his constitutional powers under the Constitution of the Republic of Iraq
The aim of the research is try to answer the questions about the importance of the participation of scientists in the scientific researcher Google Scholar for the professor and the university, and the extent of participation of Iraqi universities, and the rank of the University of Qadisiyah, and the number of participants and teachers of this engine, The research came out with several conclusions, the most important of which is that (21%) of university professors are involved in the google engine and most of the participants did not carry their full research through the site
The area around the Suez Canal has been chosen particularly Sinai to implement the new Suez Canal project parallel to the original 72-km-long channel due to the importance of the commercial site of the Arab Republic of Egypt, competing with shipping lanes, to accommodate the increasing maritime traffic passing through the Suez canal, and to provide special services for trade world and reduce the economic cost of marine trip. The establishment of six tunnels for automobile and railway transport to Sinai The cost of the establishment of this new channel and the establishment of the tunnels about (2.8) billion, of which 4 billion cost of the new channel. Project implementation period is one year. The new proj
... Show MoreAfter more than ten years of successful march of the European single currency and EU countries faced a crisis in one of its debt, which recently joined the monetary union is not Greece . Perhaps mpre than th effects of this crisis, the fact that its consequences were not confined to Greece alone , but expand it to include all EU countries in general and the countries of the European Monetary Union in particular.
Sine the debt crisis that emerged Greek and talk a lot a bout their effects on the global economy and the potential harm done th the situation of the global economy recovers from the global financial crisis (mortgage crisis), or delayed and also the fears of other crises to other member states suf
... Show MoreIn The Name of Allah Most Gracious Most Merciful
In this research, I will deal with the significance of the imperative and the disagreement of the fundamentalists in the general requirement by dividing it into an introduction and two sections. , and the appropriate indication.