In this research, damping properties for composite materials were evaluated using logarithmic decrement method to study the effect of reinforcements on the damping ratio of the epoxy matrix. Three stages of composites were prepared in this research. The first stage included preparing binary blends of epoxy (EP) and different weight percentages of polysulfide rubber (PSR) (0%, 2.5%, 5%, 7.5% and 10%). It was found that the weight percentage 5% of polysulfide was the best percentage, which gives the best mechanical properties for the blend matrix. The advantage of this blend matrix is that; it mediates between the brittle properties of epoxy and the flexible properties of a blend matrix with the highest percentage of PSR. The second stage included reinforcing the best blend matrix of epoxy-polysulfide (the blend matrix with the best percentage of polysulfide resulted from the previous stage), by different volume percentages of short fibers (Carbon& Glass) separately and randomly. The volume percentages of fibers were (2.5%, 5%, 7.5%, and 10%). The third stage included reinforcing the blend composites with highest percentages of carbon and glass fiber, by different weight percentages of nano-particles (Red mud& Fly ash) separately. The weight percentages of particles were (0.5%, 1%, 1.5%, and 2%). The experimental results showed that blending polysulfide rubber with epoxy increased the damping ratio. As for reinforcement materials, they decreased the damping ratio, where glass fiber composites have significantly higher damping ratio than other composites.
While conservative access preparations could increase fracture resistance of endodontically treated teeth, it may influence the shape of the prepared root canal. The aim of this study was to compare the prepared canal transportation and centering ability after continuous rotation or reciprocation instrumentation in teeth accessed through traditional or conservative endodontic cavities by using cone-beam computed tomography (CBCT).
Forty extracted intact, matured, and 2-rooted human maxillary first premolars were selected for this
(7)
(7)
The virulent genes are the key players in the ability of the bacterium to cause disease. The products of such genes that facilitate the successful colonization and survival of the bacterium in or cause damage to the host are pathogenicity determinants. This study aimed to investigate the prevalence of virulence factors (esp, agg, gelE, CylA) in E. faecalis isolated from diverse human clinical collected in Iraqi patient , as well as to assess their ability to form biofilm and to determine their haemolytic and gelatinase activities. Thirty-two isolates of bacteria Enterococcus faecalis were obtained, including 15 isolates (46.87%) of the urine, 6 isolates (18.75%) for each of the stool and uterine secretions, and 5 isolates (15.62%) of the wo
... Show MoreThe porosity of materials is important in many applications, products and processes, such as electrochemical devices (electrodes, separator, active components in batteries), porous thin film, ceramics, soils, construction materials, ..etc. This can be characterized in many different methods, and the most important methods for industrial purposes are the N2 gas adsorption and mercury porosimetry. In the present paper, both of these techniques have been used to characterize some of Iraqi natural raw materials deposits. These are Glass Sand, Standard Sand, Flint Clay and Bentonite. Data from both analyses on the different types of natural raw materials deposits are critically examined and discussed. The results of specific surface are
... Show More
Abstract
The current research aims to identify the impact of triangular bridging strategy in the acquisition of sociology of fourth-stage students. To achieve the research objective, the following null hypotheses were adopted: there are no statistically significant differences at a significance level (0, 05) between the average grades of the experimental group students who studied the triangular bridging strategy in acquiring concepts of sociology and average grades of the control group. The researcher has selected the fourth-stage students from Alexandronah School for girls that s related to the Directorate General of Baghdad the sample consisted of (87) students at litera
... Show MoreThe research talked about one of the important social subject that care public so cities which is .
This subject deals with three subdivisions papers :-
The first one deals with the reasons of unemployment mentioned the definition of it in addition to make a comparison between it and inertia . then talked specially about unemployment that had got in our wounded country become of wars in it .
It had a branch talked about in Islamic society .
The second one deals with the negative results of unemployment specially economic , moral and social with their roles in spreading negative phenomenon in our society as terrorist , stolen … etc …
The third one deals with the ways of reducing unemployment and trying to limit it , tha
the door of interpretation cannot be closed; Because the Qur’an is a living message, until the Day of Judgment, and Muslims continue to come to it, study it, stir it up, move with it, and live in its shadows until the Day of Judgment.
In anticipation of the blessing of revelation and the lights of revelation, and in pursuit of the service of the Book of God, I decided to choose the subject of my research:
Despondency in the Qur’an an objective study
As the study of one of the topics of the Qur’an on the foundations and steps of objective interpretation makes the reader stand on the Qur’an’s method in dealing with various problems and topics.
This research deals with a disease of the diseases our Muslim society, which works in the
body operate deadly epidemics in the bodies and of bodies, but it is extravagant; has spread
and rampant in our uncle everything which threatens significant damage in this life and the
afterlife, as well as that it shows that Alasirafla limited to extravagant in wasting money and
with this blessing should not have, and not be used as created him .
Excessive linked to all aspects of life, physical and moral it has many pictures and various
forms, came at the forefront of research and five sections:
The first topic: the meaning of truth and extravagant.
The second topic: Photos extravagant reprehensible contained in the Koran.<
(18)
(4)
