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.
Background: The aim of the present study is to evaluate the esthetic smile in sample of Iraqi adults and to assess the gender differences. Materials and Methods: 100 persons (50malesand 50 females had class I normal dental and skeletal selected for this study.Clinical examination and digital photograph with posed smile were performed for each individual. Six linear soft tissue parameters in each photograph using AutoCAD program 2011. Five visual and four quantitative evaluations of the smile were studied for eachsubject. The smile arch and index, buccal corridor spaces (BCSs) were studied.Descriptive statistics of the measurements were calculated. Independent student’s ttestswere used to evaluate the gender differences. Statistics: Desc
... Show MoreInelastic transverse and longitudinal form factors of same parity have
been studied for B 10 nucleus in the frame work of the shell model for
many particles, by using He 4 as an inert core and the remaining
particles were distributed in 3 / 2 1 / 2 1p ,1p which form the model
space. The calculations of the present work based on the harmonic
oscillator potential with fixed size parameter (b). Here we use the
first order correction for the perturbation theory and the interaction
from Cohen-Kurath (CK). Adding the core-polarization effects to
form factors calculations gave a good agreement with the
experimental data. Calculations have been performed for the
transverse excited states of: (1 ,0 )at ( E 0.178M
The research aims to demonstrate the role of organizational justice as an independent variable in influencing the achievement of development of the sense of psychological ownership of workers as a dependent variable. The current research variables were distinguished as being effective variables in terms of the field and affecting the achievement of success for organizations. In order to achieve this goal, it was applied on a sample of employees in the Iraqi Ministry of Transport employees, whose number reached (84) individuals, and the data were collected through the questionnaire as a main tool, to come out with a set of conclusions that contribute to raising the levels of the researched company, and based on the importance of the
... Show MoreThe pathogenicity of S. saprophyticus was studied in mice. A group of white mice were injected transurethrally using a catheter with S. saprophyticus S67 cell suspension in a concentration reached 109 CFU/ml. concomitantly, the role of its peptidoglycan in the pathogenicity was studied by injecting another group of mice with 0.3 mg/0.2 ml of partially purified S. saprophyticus S67 peptidoglycan extract. After autopsy, kidneys and urinary bladder showed several histopathological changes both in cells and peptidoglycan injected mice, included: hydropic degeneration, glomerulus shrinkage, congestion of renal vessels, infiltration of inflammatory cells, and dekeratinization in urinary bladder.
Soil stabilization with liquid asphalt is considered as a sustainable step towards roadway construction on problematic subgrade soil, there are no requirements to import good quality materials or to implement energy consumption, but to mix the readily available soil with liquid asphalt through the cold mix technique. In this work, collapsible soil obtained from Nasiriya was mixed with asphalt emulsion, lime, and combinations of lime and asphalt emulsion (combined stabilization) and tested in the laboratory for California bearing ratio in dry and soaked conditions. Field trial sections have been prepared with the same combinations and subjected to plate bearing test. The influence of combined stabilization on the structural properties in ter
... Show MoreThe general assumption of linear variation of earth pressures with depth on retaining structures is still controversial; investigations are yet required to determine those distributions of the passive earth pressure (PEP) accurately and deduce the corresponding centroid location. In particular, for rigid retaining walls, the calculation of PEP is strongly dependent on the type of wall movement. This paper presents a numerical analysis for studying the influence of wall movement on the PEP distribution on a rigid retaining wall and the passive earth thrust location. The numerical predictions are remarkably similar to existing experimental works as recorded on scaled test models and ful
A novel mixed natural coagulant has been developed to remove sewage pollutants and heavy metals from Qanat- al- Jayesh by using low cost adsorbent natural materials. In these materials, significant interaction contains Arabic gum mixed with extracted silica from rice husk ash (natural coagulants) by the Batch device approach, using two variables, pH values ranging from 5-8 and contact times between 0.25-5 hrs. All wastewater samples were collected after treatment by adsorbents and examined for determination of residual heavy metal concentrations: Pb, Ni, Zn and Cu by atomic absorption spectroscopy (AAS), turbidity, pH, total dissolved salts (TDS), electrical conductivity (EC) and total salinity (TS). The results obtained indicate Th
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