The photooxidative degradation process of plastics caused by ultraviolet irradiation leads to bond breaking, crosslinking, the elimination of volatiles, formation of free radicals, and decreases in weight and molecular weight. Photodegradation deteriorates both the mechanical and physical properties of plastics and affects their predicted life use, in particular for applications in harsh environments. Plastics have many benefits, while on the other hand, they have numerous disadvantages, such as photodegradation and photooxidation in harsh environments and the release of toxic substances due to the leaching of some components, which have a negative effect on living organisms. Therefore, attention is paid to the design and use of safe, plastic, ultraviolet stabilizers that do not pose a danger to the environment if released. Plastic ultraviolet photostabilizers act as efficient light screeners (absorbers or pigments), excited-state deactivators (quenchers), hydroperoxide decomposers, and radical scavengers. Ultraviolet absorbers are cheap to produce, can be used in low concentrations, mix well with polymers to produce a homogenous matrix, and do not alter the color of polymers. Recently, polyphosphates, Schiff bases, and organometallic complexes were synthesized and used as potential ultraviolet absorbers for polymeric materials. They reduced the damage caused by accelerated and natural ultraviolet aging, which was confirmed by inspecting the surface morphology of irradiated polymeric films. For example, atomic force microscopy revealed that the roughness factor of polymers’ irradiated surfaces was improved significantly in the presence of ultraviolet absorbers. In addition, the investigation of the surface of irradiated polymers using scanning electron microscopy showed a high degree of homogeneity and the appearance of pores that were different in size and shape. The current work surveys for the first time the use of newly synthesized, ultraviolet absorbers as additives to enhance the photostability of polymeric materials and, in particular, polyvinyl chloride and polystyrene, based mainly on our own recent work in the field.
التعددية السياسية بين الرفلض والقبول دراسة نظرية لأبرز الاتجاهات الاسلامية المعاصرة
Sliver / Sliver chloride is as old used from human but the sliver / sliver chloride nanoparticles have only recently been recogenized. They have used in medicin and agiculture. In the present study have been investigation the effecte biosynthesis Sliver / Sliver chloride nanoparticles as antibacterial by demonstrated that Ag / AgCl NPs arrest the growth of many bacterial: S.typhimurium, k. pneumonia. S. aureus, L.monocytogenes, B. Anthracis, E. coli, C. frundi, S. Pneumonia, P. Aeruginosa. The elements compestion and crystallization panal of biosynthesized nanoparticles were chracterazated by FTIR, XRD and SEM. From XRD, It is confirmed the synthesized nanoparticles contain Sliver / Sliver chloride elements. Synthesized Ag / AgCl NPs showed
... Show MoreThe process of cognitive representation includes mental activities such as perception, concepts formation and decision making leading to formation of Cognitive representation where the need for Cognition is one of basic humane needs promoting individuals to have more information.
This Study aims to measure the level of Cognitive representation among gifted Schools, the level of need for Cognition among them, recognize statistical Significant differences with Cognitive representation according to gender Variable and recognize the Correlation between Cognitive representation and the need for Cognition among giftel schools . The sample Consists of subsample of mair application one Consisting of( 400) students, noting that the first sampl
Background: Several pathologies of the oral cavity have been associated with stress. Dental students need to gain assorted proficiencies as theoretical knowledge, clinical proficiencies, and interpersonal dexterity which is accompanied with high level of stress. Uric acid is the major antioxidant in saliva. The aim of this study is to assess the dental caries experience among dental students with different levels of dental environment stress in relation to physicochemical characteristics of whole unstimulated saliva.
Materials and Methods: the total sample is composed of 300 dental students (73 males, 227 female) aged 22-23 years old, from collage of dentistry / university of Baghdad, from the 4t
... Show MoreIncident laser power and concentration effects on fluorescence emission from DCM dye in PMMA polymer have been investigated. Different concentrations of the dye were used. It was found that the fluorescence intensity increased with increasing of the concentration of the dye, with a red shift. In addition, it was found that the fluorescence intensity increased with the increase of the incident laser power I0.
The research aims to verifying the tax exemptions granted in accordance with the Iraqi tax legislations, showing their suitability for basic tax rules, and identifying their role to reduce the tax evasion phenomenon and the negative effects resulting therefrom, which arerepresented by a decrease in the proceeds of tax revenue and therefore leadings to a reduction of public revenues of the state. Also, the research tries to identify the ways to reduce cases of tax evasion due to their reflection positively on the public budgetof the state. The data of the research was collected through two models of questionnaires distributed to a sample of taxpayers from some professions and a sample of the tax administration staff. The research has reac
... Show MoreAbstract
The issue of inequality in distribution of income and / or consumption expenditure is related to economic welfare because there is an inverse relationship between the economic welfare on the one hand, and the degree of inequality, on the other hand. Despite the fact that inequality is considered as normal phenomenon in every society, but if it exceeded certain limits it will lead to undesirable economic, social and political consequences. Therefore, the availability of indicators about inequality is a necessary tool for planning and evaluation of economic development programs. So, current study is aiming at measuring and analyzing the degree of inequality in distribution of consumpti
... Show MoreBACKGROUND: Polycystic ovary syndrome(PCOS) is one of the most common endocrine disorder affecting women in reproductive age. No single etiologic factor fully accounts for the spectrum of abnormalities in the polycystic ovary syndrome. Different changes in hormonal, metabolism and the inflammatory markers as squealy of PCOS with adverse effect on the women life. OBJECTIVE: To study the relationship between polycystic ovary syndrome and levels of C-reactive protein, human interleukin and hormonal and metabolic alteration in women with PCOS PATIENTS AND METHODS: Thirty women with Polycystic Ovary syndrome (PCOS) and other thirty women without PCOS were included. Venous blood samples were taken in early follicular phase of menstrual cycle [day
... Show MoreIn this paper, we deal with a dynamical system that can demonstrate a chaotic attractor of Rossleroscillator. We simulate the Rosslerequations numerically then we investigate the model experimentally. Numerically, the Rossler parameter a and b were fixed and c was changed.The evolution of the system exhibits period, period-doubling, second period doubling, and chaos when control parameters are changed. This evolution can be seen by analyze the time series, the bifurcation diagrams and phase space. Experimentally, the evolution of the system exhibited the same numerical behavior by changing the resistance (Rv) in Rossler circuit that represent as control parameter.
Background: Primary healthcare in Egypt has undergone significant reforms since the 1990s, including the pioneering Family Health Program (FHP). However, limited evaluation exists regarding the FHP's impact on enhancing the delivery of primary healthcare services. The primary objective of this study was to analyze and understand the efficiency and effectiveness of the FHP in altering the delivery of primary healthcare in Egypt. We aimed to outline the fundamental characteristics of the primary healthcare system, compare them between the conventional and the newly reformed FHP centers, and gauge the awareness level of these variances among key decision-makers, focusing specifically on Cairo, Egypt. Methods: This cross-sectional study employe
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