Because of Cadmium selenide quantum dots (CdSe quantum dots) has a tuning energy gap in the visible light range, therefore; it is provided a simple theoretical model for the absorption coefficient of CdSe quantum dots, where the absorption coefficient determines the extent to which the light of a material can penetrate a specific wavelength before it is absorbed. CdSe quantum dots have an energy gap can be controlled through two effects: the temperature and the dot size of them. It is found that; there is an absorption threshold for each directed wavelength, where CdSe quantum dots begin to absorb the visible spectrum at a size of 1.4 nm at room temperature for a directed wavelength 300 nm. It has been observed that; when the wavelength is increasing its absorption threshold is increased. For wavelengths (400, 500, 600) nm, the absorption thresholds for each quantum sizes are (1.8, 2.2. 3.2)nm respectively. On the other hand, a rising of the temperature led to reduces the absorption coefficient value, that at 400 K for all quantum sizes, the absorption coefficient increases >2000cm−1(According to the directed wavelength) than it is at 0 K. CdSe quantum dots can be considered as one of the most promising materials because it has a tuning gap for the visible wavelengthsfor different applications, such as light-emitting diodes in different colors of the visible spectrum. It is found that; there is a good agreement between our theoretical calculations and experimental results.
One of the most frightening to children ages pre-school entry , Are those concerns about natural phenomena such as (The darkness, the sound of thunder, lightning and light, and rainfall, and storms) These natural phenomena are not familiar to the child , It may have a surprise when he/ she sees , And others intimidated , The affects of panic and fears that may lead him some psychological injury symptoms.
The fear of the dark, of the most common concerns associated with the child in his daily life , As the children's fear of the dark is reasonably fear that makes him a natural to live in the unknown , We can not identify what around him and is afraid of something collision, Or injury from somet
... Show MoreAbstract:
The use of economic resources enjoyed Iraq by especially oil resources, which constitute the main source of financial revenue, would the economic surplus outside the oil sector increases by mobilizing and rallying the labor power and turn it into an access capitalism, , was the cause of "the inaction of the productive sectors of the economy, made the investment planning process and even investment in human capital was not rationality with the increasing number of unemployed, particularly certificates and specializations high campaign, direction of the government towards market liberalism after 2003 through the, was focused not follow a clear economic policies, and the absence of planning
... Show MoreThe impact of Jurisprudence Rules in Addressing Contemporary security Challenges
Islamic jurisprudence is related to various fields of knowledge, as it is a science of great value, great in impact, and among the most prominent features of jurisprudence comes the jurisprudence rules. It regulates the principles of the doctrine for the jurist. Therefore, the main this research focuses on (the impact of jurisprudence rules in addressing contemporary security challenges). It is the relationship between jurisprudence rules and achieving security. Its fruit would be a statement of the distinguished impact of jurisprudence rules on the stability of the country, and its leading role in maintaining, strengthening, and pre
... Show MoreIn all process industries, the process variables like flow, pressure, level, concentration
and temperature are the main parameters that need to be controlled in both set point
and load changes.
A control system of propylene glycol production in a non isothermal (CSTR) was
developed in this work where the dynamic and control system based on basic mass
and energy balance were carried out.
Inlet concentration and temperature are the two disturbances, while the inlet
volumetric flow rate and the coolant temperature are the two manipulations. The
objective is to maintain constant temperature and concentration within the CSTR.
A dynamic model for non isothermal CSTR is described by a first order plus dead
time (FO
The cities are not yet a temporal status in the process of the human and civilization development. The cities consider as a life pattern, this mean that people cannot live without cities, which surround us. Several phenomena like globalization, revolution of information, technical development, increased of consumption, do not confirmed without the living in cities. The urbanization – in its simple meaning – means transferring from rural community to city community. In other word, it means that socioeconomic changes happened subject to the patterns and conditions of the urban life. Each government depend a certain policy, this policy contains set of plans and programs, that targeting to affect the population factors and the st
... Show MoreThe aim of current study is to analyze the content of intermediate stage biology books based on multiple intelligences. To do this, the researcher used the descriptive analytical approach. To analyze the three books of the intermediate stage, the author adopted content analysis tool and area unit. They were exposed to group of experts in methods of teaching biology, and measurement and evaluation. The findings of the study have shown a significant difference between what was expected and the observation of the multiple intelligences for the three biology books excluded the (social, musical, and kinetic intelligence), and there is no significant difference between the analysis' result of the biology books and the expectations of b
... Show MoreAlkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms . They are a large family of compounds synthesized by plants in addition to the bacteria, fungi, and animals, they often have pharmacological effects. The aim of this study is to isolate and identified alkaloids in a newly studied, wild Iraqi plant named
... Show MoreBecause of the fierce competition between service organizations on the one hand and the increasing demands of customers on the other. Therefore, these organizations sought to distinguish their service by taking care of all aspects. One of these important aspects is the service encounter environment and its reflection on customer emotions, so we choose the current research to clarify the importance and impact on customer satisfaction, the problem of research is how the interest of Iraqi restaurants in the service encounter environment and how to care about its elements and whether this interest is sufficient to reflect the satisfaction of the customer. the goal of the current research was to clarify how much the application of the
... Show MoreThe present study aims at answering the following questions:.
1-Which is more effective in enriching students. Vocabulary ,the use of short stories or the traditional way?
2-What extent has the use of short stories an effect upon the students. achievement in vocabulary test?
3- Is there any significant difference between the male and female student of the experimental group in vocabulary achievement test?
 
... Show MoreDestiny functional theory (DFT) calculations are undertaken in order to scrutinize the electrochemical and calcium (Ca) storage characteristics of a graphyne-like aluminum nitride monolayer (G-AlNyen) as an electrode material for Ca-ion batteries (CIBs). The results show that the change in internal energy as well as the cell voltage values for the CIB with the G-AlNyen anode are comparable to others with two-dimensional 2D nano-materials. It is shown that Ca is adsorbed primarily onto the center of a hexagonal and triangular ring of G-AlNyen with absorption energies of −2.06 and −0.42 eV. After increasing the concentration of Ca atoms on G-AlNyen, the adsorption energy as well as the cell voltage decreases. Lower values of 0.15–0.32 e
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