ebrahim aghazadeh

Authority and its relationship with the philosophical principle of cause and effect necessity is known as one of the most essential and challenging topical issues among philosophers and Islamic orators. Each of the scholars in the field has tried to express his own definition of the issue regarding his own line of thought.The present study deals with the problem regarding a library study data collection and using a descriptive-analytic method and it is fundamental considering the aim of the study. This research intends to investigate the viewpoints of Sadr-al-Motaallehin Shirazi regarding authority and cause and effect principle necessity. After probes of works and writings of Sadra, it was concluded that Sadra’s ideas were rooted in philosophical mysticism principles and he tried to represent authority compatible with cause and effect principle necessity. Believing in such a principle not only does not deny authority but also approves it. It accepts the principle that there isn’t any obligation but one can choose from among different options and this represents the borderline between responsibility and authority clearly and considers authority to be synonymous with being a follower.

To evaluate the effect of magnesium content on the microstructure and hardness of the Al-Si-Mg composites in the centrifugal casting method, three cylinders with the chemical composition of Al-20Si-XMg (X = 6, 9, 12) (as weight percent) were cast. Then the microstructure and hardness of the different radial sections were studied by optical microscope, SEM equipped with a micro-analysis system (EDS), and standard brinell hardness testing method, respectively. The phase diagram of Al-20Si-XMg system was plotted as a function of Mg% using Thermo-Calc software. Also JMat Pro software was employed to plot the variation of the mass fraction and density of the in situ formed phases during the solidification of the alloys. The results show clearly that while the coarse Mg2Si particles are formed in high Mg content alloys; however, these particles along with the primary Si particles, both, due to the low density, based on Stokes' law in fluid mechanics, are centripetally segregated towards the inner layers of the cylinders. In addition, by increasing the Mg content of the alloys from 6% to 9% then 12% the volume fraction and average size of the Mg2Si particles in inner layer of the cylinders, both, increase respectively from less than 7% to about 28% and from less than 54 microns to about 166 microns. But, since Mg2Si particles are softer than Si particles, by increasing the volume fraction of the Mg2Si particles, the hardness of the inner layers of the cylinders reduces from 86 to 81 and then 78 brinell.

In this study, centrifugal casting method was used to produce a hyper-eutectic composite Al-Mg2Si ‎with hybrid microstructure and graded hardness. For this purpose, two cylinders with a chemical ‎composition of Al-20Si and Al-20Si-9Mg (weight percent) were cast using a vertical centrifugal ‎casting machine. Then the microstructure and hardness of the cast cylinders were studied along the ‎radial direction by optical and scanning electron microscopes and brinell method, respectively. The ‎results show that in Al-20Si cast cylinder; in contrary to the outer layer which shows only a binary ‎eutectic Al-Si microstructure, the inner layer contains a high volume fraction of in situ segregated ‎primary silicon particles inside the eutectic matrix. By addition of 9% Mg to Al-20Si alloy, the inner ‎layer of the cast cylinder form a hybrid microstructure containing of both Si and Mg2Si particles ‎inside the eutectic matrix, while the outer layer shows only a ternary eutectic Al-Si-Mg2Si ‎microstructure. As a result of these microstructure changes along the radial direction of the ‎cylinders, not only the hardness of both cylinders are smoothly increased from the outer towards the ‎inner layers, but also all radial sections of the Al-20Si-9Mg cylinder in compared with the other one, ‎indicate higher hardness (about 18 brinell).

In this study, the effect of silicon content on the graded microstructure of Al-Si alloys fabricated by centrifugal casting method was investigated. For this purpose, two cylinders with a chemical composition of Al-11.9wt.% Si (hypoeutectic alloy) and Al-20wt.% Si (hypereutectic alloy) were cast through vertical centrifugal casting method. Then the microstructure and hardness of radial sections of the cast cylinders were studied using optical/scanning electron microscopes and standard Brinell test method, respectively. According to the results, two hypo and hypereutectic Al-Si cylinders illustrate two different patterns of functionally graded microstructure thus hardness along the radial direction. In hypoeutectic cylinder, due to the segregation of the heavy and soft α-Al phase in centrifugal force direction, the outer and inner layers show hypoeutectic and eutectic microstructures, respectively. While in the hypereutectic cylinder due to the segregation of the light and hard primary Si particles in the centripetal direction, the outer and inner layers contain eutectic and hypereutectic microstructures, respectively. As a result of these continuous and gradual microstructural changes in radial direction of the cylinders; firstly: the hardness of all radial sections in hypereutectic cylinder is about 10 Brinell more than the hypoeutectic one; secondly: the inner layer of hypoeutectic and outer layer of hypereutectic cylinders both with full eutectic microstructure show similar hardness; thirdly: the hardness of both cylinders moderately increase from outer periphery towards the inner periphery of the cylinders.

Today, due to the presence of new technologies and changes in library' mission, they have become a place for providing information services rather than to store books; therefore,this challenges assessing the quality and suitability of the resources that it contains. This study aimed to evaluate the efficiency and utilization of the Central University Library' databases of medical students and faculty deals.This descriptive study was conducted; the population encompassed EBSCO databases, PubMed, Science Direct and Springer shared to the central library of Ahvaz Jundishapour University of Medical Sciences; and frequency method was used to collect data.After data collection, findings indicated that significant differences existed between the usage rate of databases, and Pubmed was the highest use in this regard. Moreover, according to the academic disciplines variation, the use of databases between different users was so significant that most users of Medical School and School of Dentistry showed the lowest rate. In addition, EBSCO databases and Springer which rarely provide full-text articles were indicated the lowest rate among users mentioned that due to time allocated and it was not economically affordable.It is the fact that the use of databases is inevitable, since some databases are required to pay a subscription, therefore, users must be more careful to select and subscribe them in order to reduce affordably the university' economical cost and to increase its usefulness to users.

Aim and Death anxiety, death depression, and death obsession are dimensions of pathological attitudes toward death.The scales of death anxiety & death obsession has been validate in Iran. The aim of this study was to investigate validating of death depression scale.Methods and Materials: The current study was conducted in survey and cross sectional context. A group of 894 normal participants, using Stratified random sampling method, took part in this research. Participants answered to the Death Depression Scale (Templer et al, 1990) and The Death Anxiety Scale (Templer, 1970). Data were analyzed using explanatory factor analysis of variance and Pierson correlation methods. Principal Component Analysis with promax rotation showed multidimensional structure of scale and extracted four factors (49.71percent of total variance) which were labeled death despair, death finality, death loneliness & death acceptance. Concurrent validity reported parallel using of The Death Anxiety Scale, showing good coefficient. However three types of reliabilities, test retest (r= 0.78 p<0.001), split half (r= 0.77 p<0.001) & internal constancy (r= 0.76 p<0.001) were reported. Based on these results, it was concluded that the Death Depression Scale has good validity and reliability in Iranian population and it can be used, as valid measure, in empirical studies surrounding death distress.