السبيعي، عهود ناصر سعيد

This thesis is devoted to study the effect of two-temperature and different fields on plane waves of generalized thermoelasticity with three theories (Classical (CT), Lord-Shulman (L-S)and Green-Lindsay (G-L)). This thesis consists of sex chapters. The first chapter is an introductory and comprises of historical background, recent developments, literature survey on the subject and applied fields in addition to an outline of basic governing equations to thermoelasticity. The remaining chapters are study the effect of rotation, gravity field, initial stress, two-temperature, magnetic field with reflection and laser pulse on an isotropic homogeneous thermoelastic medium. After presentation of the fundamental equations of the problem, It is formulated in the dimensionless form and then solved analytically using the normal mode analysis method and the harmonic function. The physical quantities are obtained and tested by a numerical study using the parameters of copper as a target. The results are presented in group of figures and discussions are given.

الثمالي، أسماء وصل الله بركي

The purpose of the present study was to evaluate the protective effect of vitamin E against the alternations induced by two different doses of HgCl2 in liver and kidney of male mice. Some biochemical markers during acute HgCl2 intoxication were studied to examine how the mice respond to this pollutant. The effects of HgCl2 were investigated by assessing toxicological end points in the form of body weight, hematological parameters and histopathological changes in hepatic and renal tissue of male mice. Moreover, HgCl2- induced hepatotoxicity that was estimated by determining serum alanine transferase (ALT) and lactate dehydrogenase (LDH) activities. In addition, some blood parameters (cholesterol, high density lipoprotein, low density lipoprotein, triglycerides and total proteins content), indicative of metabolic disturbances, were determined. HgCl2-induced nephrotoxicity in terms of serum uric acid and creatinine concentration were also measured. The oxidative stress was determined by measuring the lipid peroxidation (LPO) levels, superoxide dismutase (SOD) activity and reduced glutathione (GSH) content in liver and kidney tissues. The present study has also been conducted to clarify the protective role of vitamin E to minimize the negative effects of HgCl2 in the male mice.

البقمي، مهدي منيف مهدي

Hexagonal ferrites are a group of magnetic compounds, which all have high resistivity, high saturation magnetization and are thermally stable well above their Curie temperature. Hexagonal ferrites can be classified into different types according to their chemical formulas and crystal structures. M ferrites are in the most commercially important permanent magnetic materials globally. Different ions can be substituted for Ba2+and Fe3+ in M-type phase ferrite. Consequently, the magnetic and electronic parameters of the ferrites can be adjusted or controlled, and their performance can be improved. So, main object of this study was to synthesis and characterize M-type hexagonal Strontium hexaferrite nanopowders (SrFe12O19); as hard magnetic materials for industrial applications through simple route. In the modern electronic devices, the present trend is to further increase the performances of the devices: higher capacitance coupled with smaller size. To achieve this goal, powders with improved quality, uniform and fine particle sizes with a narrow size distribution and suitable stoichiometry are required to develop the correct microstructure and attain the required performances. Low temperature, wet chemical routes offer an exciting possibility for the synthesis of high purity, homogeneous, ultrafine and multicomponent powders from which electronic components with tailored and predictable properties could be prepared. Selfcombustion tartaric acid precursor route was used to produce single phase of nanocrystalline Strontium hexaferrite powder with low-processing temperature, homogenous microstructure, narrow size distribution and uniform shape. This study investigated the manipulation of synthesis conditions namely annealing temperature (900-1350oC) and Sr:Fe molar ratio on the crystal structure, crystallite size, microstructure and magnetic iv properties of SrFe12O19 ferrites prepared by tartaric acid precursor method. The optimum conditions for synthesis of hexaferrites were systematically determined. The effects of La3+cations substitution on the formation, microstructural and magnetic properties of M-types hexagonal strontium hexaferrites SrFe12-xLaxO27 (x = 0.2, 0.4 and 0.6) was under investigation. Various characterization techniques were employed to study the structural and physical properties of magnetic materials. The changes in the crystal structure and lattice parameters were characterized using X-ray diffraction. The surface morphology and shape of the bulk and nanoparticles were examined using scanning electron microscopy (SEM). The changes in the magnetic properties of the produced powders were measured using vibrating sample magnetometer (VSM). The obtained results showed that well crystalline single phase of SrFe12O19 and SrFe11.8La0.2O19 M-hexagonal ferrite were realized at low annealing temperature 1100 °C for 2 h at Sr2+:Fe3+ concentrations ≥1.1:12. Hexaferrite formed at Sr2+:Fe3+ molar ratio 1.1:12 has larger crystallite size than that observed at both lower and higher molar ratios while the crystallite size of SrFe12-xLaxO19 highly decreases with increasing the La3+ ion content. The morphological microstructures of the formed particles were strongly dependent on the annealing temperature and Sr2+:Fe3+ molar ratio. Wide saturation magnetization Ms (37.26-66.19 emu/g) and coercivities (275.09– 2107.8Oe) were achieved at different synthesis conditions of SrFe12O19. Maximum values of saturation magnetization Ms (62.16 emu/g) and the coercive force Hc (1479.3 Oe) were observed at x = 0.2 and annealing temperature 1200°C.

البقمي، مهدي منيف مهدي

Hexagonal ferrites are a group of magnetic compounds, which all have high resistivity, high saturation magnetization and are thermally stable well above their Curie temperature. Hexagonal ferrites can be classified into different types according to their chemical formulas and crystal structures. M ferrites are in the most commercially important permanent magnetic materials globally. Different ions can be substituted for Ba2+and Fe3+ in M-type phase ferrite. Consequently, the magnetic and electronic parameters of the ferrites can be adjusted or controlled, and their performance can be improved. So, main object of this study was to synthesis and characterize M-type hexagonal Strontium hexaferrite nanopowders (SrFe12O19); as hard magnetic materials for industrial applications through simple route. In the modern electronic devices, the present trend is to further increase the performances of the devices: higher capacitance coupled with smaller size. To achieve this goal, powders with improved quality, uniform and fine particle sizes with a narrow size distribution and suitable stoichiometry are required to develop the correct microstructure and attain the required performances. Low temperature, wet chemical routes offer an exciting possibility for the synthesis of high purity, homogeneous, ultrafine and multicomponent powders from which electronic components with tailored and predictable properties could be prepared. Selfcombustion tartaric acid precursor route was used to produce single phase of nanocrystalline Strontium hexaferrite powder with low-processing temperature, homogenous microstructure, narrow size distribution and uniform shape. This study investigated the manipulation of synthesis conditions namely annealing temperature (900-1350oC) and Sr:Fe molar ratio on the crystal structure, crystallite size, microstructure and magnetic properties of SrFe12O19 ferrites prepared by tartaric acid precursor method. The optimum conditions for synthesis of hexaferrites were systematically determined. The effects of La3+cations substitution on the formation, microstructural and magnetic properties of M-types hexagonal strontium hexaferrites SrFe12-xLaxO27 (x = 0.2, 0.4 and 0.6) was under investigation. Various characterization techniques were employed to study the structural and physical properties of magnetic materials. The changes in the crystal structure and lattice parameters were characterized using X-ray diffraction. The surface morphology and shape of the bulk and nanoparticles were examined using scanning electron microscopy (SEM). The changes in the magnetic properties of the produced powders were measured using vibrating sample magnetometer (VSM). The obtained results showed that well crystalline single phase of SrFe12O19 and SrFe11.8La0.2O19 M-hexagonal ferrite were realized at low annealing temperature 1100 °C for 2 h at Sr2+:Fe3+ concentrations ≥1.1:12. Hexaferrite formed at Sr2+:Fe3+ molar ratio 1.1:12 has larger crystallite size than that observed at both lower and higher molar ratios while the crystallite size of SrFe12-xLaxO19 highly decreases with increasing the La3+ ion content. The morphological microstructures of the formed particles were strongly dependent on the annealing temperature and Sr2+:Fe3+ molar ratio. Wide saturation magnetization Ms (37.26-66.19 emu/g) and coercivities (275.09– 2107.8Oe) were achieved at different synthesis conditions of SrFe12O19. Maximum values of saturation magnetization Ms (62.16 emu/g) and the coercive force Hc (1479.3 Oe) were observed at x = 0.2 and annealing temperature 1200°C.

السفياني، جميلة علي

The present study aimed to investigate English as a foreign language (EFL) female teachers' and students' attitudes about corrective feedback (CF) in oral communication classes. It also explored EFL female teachers' and students' preferences for CF types, errors types that need CF, and timing of CF. The study was additionally designed to compare EFL teachers' actual practices of CF with students' preferences. The sample of the study consisted of 52 EFL female teachers and 115 EFL female students in Foreign Languages Department (FLD) at Taif University. To achieve the aims of the study, the researcher used two questionnaires: one for the teachers and one for the students; and conducted several classroom observations. Having data collected, data were quantitatively and qualitatively analyzed. The results showed that EFL female teachers and students consider CF an important teaching technique in oral communication classes. Such a tecquenique helps students notice their errors and in turn leads to improvement in their English language competency. The results also showed that EFL teachers preferred CF types which push students to self-correction whereas students preferred explicit feedback with metalinguistic explanation. With regard to types of errors, EFL teachers preferred providing CF mostly on errors which hinder listeners' understanding. Similarly, EFL students preferred to receive CF on errors that affect a listener's understanding. Regarding timing of CF, both EFL teachers and students preferred CF mostly after the student finishes speaking. The classroom observations indicated that there is a mismatch between teachers' actual classroom practices and students' preferences. The findings of the study contribute to a better understanding of EFL female teachers' and students' attitudes and preferences about CF in oral communication classes at the university level in Saudi Arabia. These findings should contribute to reducing the gap between teachers' actual practices of CF in EFL classrooms and students' preferences.

الطلحي ، فاطمة حمادي

عبد الله ، أسماء سعيد

In this work, new electrochemical sensors were prepared for the electrochemical determination of some cephalosporins compounds (cefoxtin, cefotaxime and cefepime) in powder pharmaceutical formulations. The electrochemical sensors were prepared by modification of carbon paste electrodes by different compounds such as CTAB and carbon nanotube. The modified electrochemical sensors were characterized using scanning electron microscope (SEM). The electrochemical behavior of the prepared electrochemical sensors were characterized by electrochemical methods such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrochemical behavior of some cephalosporins compounds were studied on the surface of the prepared sensors using square wave voltammetry which was used in the estimation of direct electrochemical of some cephalosporins compounds such as cefoxitin, cefotaxime and cefepime). Cephalosporins compounds were detected at the prepared sensors after optimization the experimental conditions such as the type of supporting electrolyte and pH value. The prepared electrochemical sensors were applied to determination of the cephalosporins in powder pharmaceutical formulations.

القرشي ، منال عبد الله ضيف الله

Using the critical perspectives developed in postcolonial studies, minority discourse, and multiculturalism, this thesis aims to highlight the conflict in Maxine Hong Kingston’s The Woman Warrior between the Chinese minority culture and the dominant American one, as well as the gap between earlier and later generations of Chinese-Americans. It also detects the novelist's quest for self-identity as a second-generation Chinese girl caught in-between the American culture and the received Chinese culture. As a Chinese-American woman, Maxine Hong Kingston realizes the difficulty of survival in a highly complex social structure that is characterized by sexism, racism, and classism. Thus, she looks for a new means for survival, which she discovers in re-writing her own Chinese culture. The best example of such practice can be found in her book The Woman Warrior: Memoirs of a Girlhood among Ghosts (1976), where Kingston interweaves the literary forms of memoir, myth, legend, and her own experience as a girl growing into adulthood in a culturally diverse environment. This study demonstrates that Kingston is able to fashion a Chinese-American identity that is neither wholly Chinese nor completely American, but both: a form of a new identity which reconciles the differences between her ancestral homeland and her new one in diaspora. In seeking her new identity, Kingston has to deal with race and culture on the one hand, and gender and generational gaps on the other hand. Additionally, she has to reconcile two different cultures to find a unique hybrid cultural voice to articulate her experience – a voice that entails resisting one culture and embracing another alternately. This thesis shows how a story is not just a story. In fact, the thesis will go on to argue that Kingston's work does not only tell us about the life of a woman in America, but it also reveals America's important role in her personal and literary life. Finally, this study will demonstrate how Kingston, through her literary re-writing or re-narration of Chinese tales, legends and myths, can translate, transmit, and illustrate her original culture. Against Chinese-American authors who ignore their history and new identity formation in the United States and who prefer instead to reinforce their identification with China, Maxine Hong Kingston uses "re-writing" as a strategy to fashion a new identity and create a voice for herself as a hybrid Chinese American woman.

القرشي، منال عبدالله ضيف الله

Using the critical perspectives developed in postcolonial studies, minority discourse, and multiculturalism, this thesis aims to highlight the conflict in Maxine Hong Kingston’s The Woman Warrior between the Chinese minority culture and the dominant American one, as well as the gap between earlier and later generations of Chinese-Americans. It also detects the novelist's quest for self-identity as a second-generation Chinese girl caught in-between the American culture and the received Chinese culture. As a Chinese-American woman, Maxine Hong Kingston realizes the difficulty of survival in a highly complex social structure that is characterized by sexism, racism, and classism. Thus, she looks for a new means for survival, which she discovers in re-writing her own Chinese culture. The best example of such practice can be found in her book The Woman Warrior: Memoirs of a Girlhood among Ghosts (1976), where Kingston interweaves the literary forms of memoir, myth, legend, and her own experience as a girl growing into adulthood in a culturally diverse environment. This study demonstrates that Kingston is able to fashion a Chinese-American identity that is neither wholly Chinese nor completely American, but both: a form of a new identity which reconciles the differences between her ancestral homeland and her new one in diaspora. In seeking her new identity, Kingston has to deal with race and culture on the one hand, and gender and generational gaps on the other hand. Additionally, she has to reconcile two different cultures to find a unique hybrid cultural voice to articulate her experience – a voice that entails resisting one culture and embracing another alternately. This thesis shows how a story is not just a story. In fact, the thesis will go on to argue that Kingston's work does not only tell us about the life of a woman in America, but it also reveals America's important role in her personal and literary life. Finally, this study will demonstrate how Kingston, through her literary re-writing or re-narration of Chinese tales, legends and myths, can translate, transmit, and illustrate her original culture. Against Chinese-American authors who ignore their history and new identity formation in the United States and who prefer instead to reinforce their identification with China, Maxine Hong Kingston uses "re-writing" as a strategy to fashion a new identity and create a voice for herself as a hybrid Chinese American woman.

البيشي ، نورة محمد فايز

This is a study of the effects of written corrective feedback (WCF) on students’ awareness of their errors in EFL writing context in the foreign languages department (FLD) at Taif university. Data on teachers' beliefs and students' preferences regarding written corrective feedback (WCF) were collected via interviews. The participants in the case study were 20 female students at the intermediate level at Taif university, divided into two equal groups (direct corrective feedback and indirect corrective feedback). Both groups were requested to write on three topics selected from their curriculum. Group A received indirect corrective feedback (ICF) in the form of error underlining and short comments. Group B received direct feedback feedback (DCF) in the form of error correction above the original errors. The data were collected and analyzed according to the error analysis approach. The main findings of the case study showed that ICF group had more improvement in their writing than the DCF group by committing less errors. The findings of the interviews showed that teachers and students valued WCF highly in teaching and learning process. Finally, students preferred ICF to DCF in language learning. This study concludes by providing some implications for teachers. Teachers should vary their corrective techniques to meet the requirements of all students and take into consideration individual differences and students' preferences regarding the type of corrective feedback

العوفي ، رشا إبراهيم

The current study aimed to shed some light on the status of the English language in our current time in relation to the Saudi society. It attempted to do that through the linguistic investigation of English mixing in Arabic print advertising discourse. The main approach used in the study is Kelly-Holmes‟ linguistic fetishism approach which focuses on the symbolic use of language. Two Arabic magazines were chosen and a quantitative analysis of the advertisements was used to investigate the percentage of the English mix and its place in the advertisements. Also a qualitative analysis was employed in investigating other aspects of English mixing such as the use of Roman script for languages other than English, use of English numbers, and English in non-Roman script in the analyzed advertisements. To determine the percentage of English mixing the study used a cline of code-mixed advertising developed by Martin (2002). In addition, the location of English elements in an ad bore indications to its function. The definition of each function is based on Bhatia‟s (1992).As a result of the quantitative analysis it was found that English was used in Arabic advertising mostly in small structures such as phrases and single lexical items in parts of the advertisements that do not have informative function. The qualitative analysis also confirmed that the main function of English mixing in Arabic advertising discourse is the Symbolic function. There is a clear tendency for employing English suggested by the high frequency of occurrences. However the nature of this mix functions mostly symbolically indicating that English remains in the level of a favorite foreign language in Saudi Arabia

حلواني ، سراء حسين أحمد

الجعيد، ندى محمد جربوع

The original work of this thesis deals with developing and design a facile synthesis of new heterocyclic nucleosides. First, azole and azine heterocyclic compounds for example, 1,2,4-triazoles, uracils, 3-benzylxantine, 1-methyl-3-benzylxanthine, were prepared, which coupled then with protected sugars, for example, 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide to give protected nucleosides.The later products obtained were deprotected by methanolic sodium methoxide to get free heterocyclic nucleosides. Some of the protected and free nucleosides obtained were tested against some fungal and bacterial species. Some of tested products showed moderate activity.

الوذيناني، تغريد غزاي فاتن

Gupta and Kundu (1999) suggested a new two-parameters distribution, named as generalized exponential (GE) distribution. It is observed that the GE distribution can be used as an alternative to the gamma distribution, log-normal distribution and Weibull distribution in many situations, but the GE distribution has a nice compact distribution function. This distribution was studied quite extensively by the authors. Kamps (1995) introduced a concept of generalized order statistics (gos). This model is very important because it contains several models of ordered random variables such as ordinary upper order statistics, upper record values, progressive type-II censored samples, sequential order statistics and Pfeifer's record values. Also, the mixture models is very important in the theoretical and applied fields specially in case of the heterogeneous population. The basic problem in this thesis is estimating all parameters of a finite mixture of GE distribution using the maximum likelihood and Bayes methods based on right censored samples of gos. Then, a comparison between the two methods will be carried out. All results will be specialized to type-II censored samples, right censored upper record values and progressively type-II censored samples. The thesis consists of four chapters: Chapter 1 : In this chapter we show a historical survey on some studies in theoretical and application which have been made on GE distribution. Also it contains some basic concepts which will be used throughout this thesis. Chapter 2 : The objectives of this chapter is estimating the parameters of a finite mixture of GE distribution based on right censored samples of generalized order statistics which include type-II censored samples, progressively type-II censored samples and upper record values using the maximum likelihood method. A simulation study is carried out to compute the mean squared errors of each estimate. Chapter 3: Our main goal in this chapter is estimating the parameters of a finite mixture of GE distribution based on right censored samples of generalized order statistics using Bayes method. A simulation study is carried out to compute the mean squared errors of each estimate. Chapter 4: We investigate and Compares between the two methods of estimation methods based on type- II censored samples, progressively type-II censored samples and upper record values.

عواجي، سحر احمد هادى

Due to the continual improvement in the manufacturing design, it is more difficult to obtain information about the lifetime of products or materials with high reliability at the time of testing under normal conditions. This makes the lifetime testing under these conditions very costly, take a long time. For this reason, accelerated life tests (ALTs) are preferred to be used in manufacturing industries to obtain enough failure data, in a short period of time, necessary to make inferences regarding its relationship with external stress variables. In ALTs, the test items are tested only at accelerated conditions, viz higher than usual levels of stress, to induce early failures. Data collected at such accelerated conditions are then extrapolated through a physically appropriate statistical model to estimate the lifetime distribution at normal use conditions. In PALTs items are tested at both accelerated and use conditions. There are two types of PALTs, one is called step PALTs and the other is called constant PALTs. In this thesis, the constant PALT applied to items whose lifetimes under design condition are assumed to follow Lindley distribution under a progressive type II censoring, Bayesian and non Bayesian estimators for the Lindley distribution parameters, are presented.