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The influence of temperature and size on the absorption coefficient of CdSe quantum dots
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Abstract<p>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<sup>−1</sup>(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.</p>
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Publication Date
Mon Apr 01 2019
Journal Name
Journal Of Educational And Psychological Researches
The Effectiveness Of A Proposed Program For Developing The Creative Abilities Of The Students At The University Of Tabuk And Its Effect On The Creative Output Of The Neom Project.
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The aim of this study was to measure the effectiveness of a proposed program to develop the creative abilities of the students of Tabuk University and its impact on the creative output of the NEOM project. The sample of the study consisted of (50) university students divided into two groups: an experimental group of 25 students who receive the proposed training program, and control group of (25) students.

 To achieve these objectives, the researcher designed and developed tools to collect the required data, which were verified their validity and reliability.

The descriptive statistics of mean, standard deviations, correlation coefficient, T test for the associated sample were used in the analysis of the results of th

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Publication Date
Tue Dec 10 2024
Journal Name
مجلة الثقافة الرياضية
The Effect of Resistance Training Using Elastic Bands on the Developmentof Specific Endurance and Performance of the Oji-mata Skill
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t: - Sports training in itself is a means, not an end. It is the core process that involves using exercises to provide an opportunity for athletes to perform their duties with the highest level of efficiency by developing and enhancing their capabilities and potential, using them to gain the greatest benefit for themselves and, consequently, for their team. This requires the selection of various methods and different means of training, focusing on specific physical and skill-related aspects. Therefore, training plans should take into account individual differences between players. Many researchers and experts in the field of sports in general, and combat sports in particular, emphasize the importance of having a holistic approach in the tra

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Publication Date
Sat Mar 01 2008
Journal Name
Al-khwarizmi Engineering Journal
Study the Effect of Carbon Fiber Volume Fraction and their Orientations on the Thermal Conductivity of the Polymer Composite Materials.
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      The effect of fiber volume fraction of the carbon fiber on the thermal conductivity of the polymer composite material was studied. Different percentages of carbon fibers were used (5%, 10%, 15%, 20%, and 25%). Specimens were made in two groups for unsaturated polyester as a matrix and carbon fibers, first group has parallel arrangement of fibers and the second group has perpendicular arrangement of fibers on the thermal flow, Lee's disk method was used for testing the specimens. This study showed that the values of the of thermal conductivity of the specimens when the fibers arranged in parallel direction was higher than that when the fibers arranged in the perpendicular direction  

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Publication Date
Mon Apr 19 2021
Journal Name
Turkish Journal Of Computer And Mathematics Education (turcomat)
The Impact Of Innovative Matrix Strategy And The Problem Tree Strategy On The Mathematical Proficiency Of Intermediate Grade Female Students
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The research aims to know the impact of the innovative matrix strategy and the problem tree strategy in teaching mathematics to intermediate grade female students on mathematical proficiency. To achieve the research objectives, an experimental approach and a quasi-experimental design were used for two equivalent experimental groups. The first is studied according to the innovative matrix strategy, the second group is studied according to the problem tree strategy. The research sample consisted of (32) female students of the first intermediate grade, who were intentionally chosen after ensuring their equivalence, taking into several factors, most notably (chronological age, previous achievement, and intelligence test). The research tools con

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Publication Date
Fri Aug 25 2023
Journal Name
Enterprenuership Journal For Finance And Bussiness
Argumentative Accounting conservatism and the performance of institutions listed on the Iraq Stock Exchange in light of the Coronavirus pandemic
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This study aims to test whether the institutions listed on the Iraq Stock Exchange have a significant correlation between the level of conservative accounting practice with the level of market share returns during the Coronavirus pandemic period as one of the policies to confront the economic repercussions of the Coronavirus pandemic. Furthermore, the sample included institutions listed on the Iraq Stock Exchange during the 2019 and 2020 years, i.e., the period before the Coronavirus pandemic and during the Coronavirus pandemic for the purpose of comparison. The market value to book value model was used, and the study found that conservative institutions had achieved the highest level of market share prices compared to non-conservat

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Publication Date
Sat Jan 01 2022
Journal Name
International Journal Of Economics And Finance Studies
THE IMPACT OF THE AUDIT COMMITTEE AND AUDIT TEAM CHARACTERISTICS ON THE AUDIT QUALITY: MEDIATING IMPACT OF EFFECTIVE AUDIT PROCESS
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Scopus (32)
Scopus
Publication Date
Tue Sep 17 2024
Journal Name
Evolutionary Studies In Imaginative Culture
The Effect of the Siberian Air Altitude on the Characteristics of the Climate of the Northern Arabian Peninsula
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The field of climatic geography focuses on the study of the Earth's surrounding atmosphere, particularly the lower (surface) part close to the Earth's surface. This field examines the interactions within the atmosphere resulting from the solar radiation that reaches the Earth and the subsequent distribution of atmospheric pressure. Consequently, certain surface pressure systems, both high and low, emerge and vary in their temporal and spatial impacts on the climate of the Arabian Peninsula. Therefore, it is essential to conduct a comprehensive and detailed study to understand the causes, development, movement, geographical distribution, and monthly and seasonal recurrence of these pressure systems. For this purpose, a minor climatic

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Crossref
Publication Date
Fri May 10 2024
Journal Name
South Asian Research Journal Of Pharmaceutical Sciences
Influence of Human Leukocyte Antigen in Susceptibility to Migraine in Patients
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Migraine affects more than one billion individuals each year across the world, and is one of the most common neurologic disorders, with a high prevalence and morbidity, especially among young adults and females. Migraine is associated with a wide range of comorbidities, which range from stress and sleep disturbances to suicide. The complex and largely unclear mechanisms of migraine development have resulted in the proposal of various social and biological risk factors, such as hormonal imbalances, genetic and epigenetic influences, as well as cardiovascular, neurological, and autoimmune diseases. Experimental findings suggest an involvement of neuroinflammatory mechanisms in the pathophysiology of migraine. Specifically, preclinical

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Publication Date
Fri Dec 01 2017
Journal Name
Journal Of Global Pharma Technology
Influence of immune engines in iraqi patients with acute myeloid leukemia
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Acute myeloid leukemia (AML) is heterogeneous disorders originated from the abnormalities in the proliferation and maturation of myeloid progenitors in bone morrow. There is a clinical correlation between immunity engines and disease progression, but this relationship is not completely clear yet. This study was designed to assess the full immune response in Iraqi patients diagnosed with AML. Patients and healthy volunteers were divided into three groups: newly diagnosed untreated, under chemotherapy treatment patients and control group. A significant reduction were seen in C4 and IFN-γ levels in both untreated and treated groups with no significant difference between untreated and treated groups. On the other hand, IL-2 and IL-8 levels inc

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Scopus
Publication Date
Fri Feb 01 2013
Journal Name
Journal Of Physical Science And Application
Photobleaching Influence in Different Phases for Coumarin 307 and Acriflavine Laser Dyes
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Abstract: Under high-excitation irradiance conditions to induce fluorescence, the dependence of photobleaching of Coumarin 307 (C307) and acriflavine (ACF) laser dyes in liquid and solid phases have been studied. A cw LD laser source of 1 mW and 407 nm wavelength was used as an exciting source. For one hour exposure time, it was found that the solid dye samples suffer photobleaching more than the liquid dye samples. This is because in liquid solutions the dye molecules can circulate during the irradiation, while the photobleaching is a serious problem when the dye is incorporated into solid matrix and cannot circulate.

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