In this work, the effects of size, and temperature on the linear and nonlinear optical properties in InGaN/GaN inverse parabolic and triangular quantum wells (IPQW and ITQW) for different concentrations at the well center were theoretically investigated. The indium concentrations at the barriers were fixed to be always xmax = 0.2. The energy levels and their associated wave functions are computed within the effective mass approximation. The expressions of optical properties are obtained analytically by using the compact density-matrix approach. The linear, nonlinear, and total absorption coefficients depending on the In concentrations at the well center are investigated as a function of the incident photon energy for different values of temperature and quantum wells size. The results show that the In concentrations, size and temperature have a significant effect on these optical properties. The positions of the resonance peaks of the absorption coefficients were blue-shifted under increasing indium compositions in the quantum wells (InGaN) and temperature while they were red-shifted with the increase in the thickness of the wells. Moreover, the amplitudes of the resonance peaks were enhanced under the increase of the In composition, the temperature, and the thickness of the quantum wells. The optical absorption in ITQW structure is slightly greater than that in IPQW one.
he research specifies important subjects which contribute in improvement of productive performance in industrial companies through study and analysis of relationships and effect between dimensions of physical work environment and industrial operations flexibility in the leathers industries company. To reach these goals the information are collected is questionnaire prepared for this purpose as a tool to analyze the practical results and are recorded for a sample of 118 persons from employees. The research uses the statistical methods and analyzes the information by using SPSS system. The research reached to many conclusions; the important one is the weakness of the company to make in to account the physical envir
... Show MoreThis study presents a comprehensive set of laboratory works for the examined soil layers extracted from Baghdad city (specifically from Alkadhimya, Alaitaifiya, and Alhurriya) to illustrate their engineering properties. The researchers have adopted the unified soil classification system for soil classification purposes. Also, the direct shear test was performed for soil samples with various degrees of saturation (0%, 25%, 50%, 75%, and 100%). The test results have shown a significant reduction in cohesion property with higher moisture content within soil samples. Also, a noticeable reduction in angle of internal friction value has occurred with such changes. Furthermore, it has been found that the bearing capacity of unsaturated soi
... Show MoreBackground: Polymers are very rarely used in their form. These modifications are carried out in order to improve the properties of polymers.Recently silver have been used successfully as antimicrobial (medical and dental) biomaterials that can prevent caries and infection of implants Purposes: The aim of the present in vitro study is to evaluate the effect of addition of silver nitrate to acrylic resin in different concentrationsthrough several tests part of these are: The effect of this additive on impact strength, transverse strength, and tensile strength of AgNO3 – loaded resin, and to assess any effect of addition of silver nitrate on coloration of acrylic resin. Materials and methods: Different concentrations of silver nitrate
... Show MoreA laboratory experiment was carried out and repeated at field of College of Agricultural Engineering Sciences, University of Baghdad in 2017. First factor was three cultivars of lupine 'Giza-1', 'Giza-2' and 'Hamburg'. Second factor was three seed weights (lower weight, medium weight and higher weight) which was following the cultivars factor. Nested design was used. Results showed supremacy of 'Giza-1' cultivar significantly and gave higher germination ratio, radical length, seedling dry weight, seedling vigour index, field emergence ratio, plant height and number of leaves per plant. The treatment ('Giza-1'×higher seed weight) was supremacy significantly and gave higher germination ratio, radical length, plumule length, and seedling vigo
... Show MoreIn this study, composite materials were prepared using unsaturated polyester resin as binder with two types of fillers (sawdust and chopped reeds). The molding method is used to prepare sheets of UPE / sawdust composite and UPE / chopped reeds composite. The mechanical properties were studied including flexural strength and Young's modulus for the samples at normal conditions (N.C). The Commercial wood, UPE and its composite samples were immersed in water for about 30 days to find the weight gain (Mt%) of water for the samples, also to find the effect of water on their flexural strength and Young's modulus. The results showed that the samples of UPE / chopped reeds composite gained highest values of flexural strength (24.
... Show MoreSuperconducting thin films of Bi1.6Pb0.4Sr2Ca2Cu2.2Zn0.8O10 system were prepared by depositing the film onto silicon (111) substrate by pulsed laser deposition. Annealing treatment and superconducting properties were investigated by XRD and four probe resistivity measurement. The analysis reveals the evolution of the minor phase of the films 2212 phase to 2223 phase, when the film was annealed at 820 °C. Also the films have superconducting behavior with transition temperature ≥90K.
The effect of 5555 strategy on reading comprehension among 4th preparatory students Assist. Prof. Dr. Hassan Khilbas Hammadi College of Education Ibn Rushd – The University of Baghdad Assistant Lecturer. Waleed Khaled Talib Directorate – General For Education Province Of AL - Anbar The purpose of study is to identify the effect of 5555 strategy on reading comprehension among 4th preparatory students. To do this, null hypothesis was postulated. The author hypothesize that there is no a statistically significant difference at (0.05) level between experimental group's scores who study reading comprehension subject following the 5555 strategy and control group's scores who study the same subject following the traditional method in readin
... Show MoreThis study was conducted at the poultry farm of the Department of Animal Production/College of Agriculture/University of Baghdad/Abu Ghraib, on 252 birds (180 females and 72 males). This study aims to observe the effect of melatonin implantation and exposure to different light colors and their interaction on characteristics of fertility and hatching of local Iraqi chickens. The birds were divided into three sections (white, red and green) each section contains two lines, one of which has been planted melatonin under the skin of the neck of birds and the other has not been planted hormones. The results showed that melatonin implantation and exposure to different light colors did not significantly affect the hatching rate of fertilized eggs a
... Show MoreThis experiment was carried out at the Field of Poultry, Department of Animal Resources, College of Agriculture, University of Baghdad, during the period from 1/5/2011 until 5/7/2011 to study the effect of adding arginine to laying hens diet on certain blood traits. A total of 100 Brown Lohmann laying hen chickens, 38 weeks of age, were randomly distributed into four treatment groups, with 25 hens for each treatment. Treatment groups were: T1: bird-fed diet with no additional arginine (control group); T2, T3, and T4: bird-fed diet supplemented with 0.4, 0.7, and 0.9%, respectively. Therefore, the total amounts of arginine in the four treatments (T1, T2, T3, and T4) become 1.1, 1.5, 1.8, and 2.0%, respectively. Results of this experiment rev
... Show Moreأثر استراتيجية التدريس البصري باستخدام الانـفوجرافيك في التحصيل والتفكير البصري لدى طلاب المرحلة المتوسطة فـي مادة الرياضيات