Effects of high activator content on fly ash-based geopolymers exposed to elevated temperatures

This article reports the influence of high alkaline activator content on the compressive strength and microstructure characteristics of a fly ash (FA) geopolymer system after exposure to elevated temperatures of 400 °C, 600 °C, and 800 °C. The sequential changes in the geopolymer gel structure after exposure to elevated temperatures and their effects on the residual strength were investigated through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the high strength of the FA geopolymers reduced after exposure to 400 °C and 600 °C and failed in return any strength after exposure to 800 °C. The SEM results showed that the high activator content generated large quantities of unreacted crystals composed mainly from silicate underwent viscous sintering process at range of temperatures of 600 °C to 800 °C, and swelling resulting in system failure. XRD results showed that the geopolymers exposed to 800 °C exhibited significant decomposition in the aluminosilicate phase and amorphous hump compared to unexposed pattern

An Assessment of Translating Rhetorical Devices in King Abdullah II’s Political Speeches into English: Metonymic Expressions as a Case Study

Rhetorical devices are certain means of aesthetic and considerable values added to texts in general, and to both expressive and vocative in particular. The general concept and purpose of rhetorical devices are commonly shared between English and Arabic; yet, the subclassifications and branches of rhetoric as a unique discipline are not equal. Their mismatch makes the assessment of rendering those concerned devices in the text thorny and not quite an easy task. In addition, the study sheds light on the act of translating such texts taking into account how the aesthetic value and equivalent effect are maintained in the TLTs. The study hypothesizes that translating rhetorical devices is a thorny task to translators, due to their different types. Also, translators are not consistent with certain methods of translation as far as rendering such rhetorical devices is concerned. The model adopted to make the translation quality assessment is that of Reiss (1971/2000) who submits a thorough method of assessment and considers text type a focal point in conducting a specific approach to translation. As for procedure and data collection concerning this study, (5) texts compising metonymic expressions have been selected to be analyzed and discussed in accordance with criteria of the model adopted. The study comes up with certain concluded points which almost verify the relevent hypotheses of the study

Mechanical and durabiliry properties of environmentally friendly Ultra-High-Performance Concrete (UHPC)

International audienceThis paper deals with mechanical and durability performances of more sustainable Ultra-High Performance Concrete (UHPC) by integrating high volumes of Blast Furnace Slag (BFS). Three substitution rates of cement by slag are explored (30%, 50% and 80%). Results show that a slag content of 30% improves slightly the compressive strength of concrete, whereas the strength of UHPCs containing 50% and 80% of slag are significantly reduced, particularly at early age. At 3 days, when the slag content increases, the porosity of UHPC mixtures with high slag content increases. In contrast, at 90 days, the volume of capillary pores decreases greatly and the global pores network becomes finer, when cement is substituted by BFS. This, results in decreasing gas permeability (1.5-6 times) and chloride diffusion (up 4 times). Results show also that all tested UHPCs have quite the same CO2 depth, after an exposure of 1 year. Indeed, the decrease of porosity, when BFS is added, is balanced by the decrease of pH, which promotes CO2 diffusion.Le présent article traite des performances mécaniques et de durabilité d'un Béton Ultra-Haute Performance (BUHP) plus durable, avec des teneurs en laitier élevées. Trois taux de substitution du ciment par des laitiers des hauts fourneaux (LHF) sont explorés (30%, 50% et 80%). Les résultats montrent qu'une teneur de 30% de laitier améliore légèrement la résistance à la compression, alors qu'avec 50% et 80% de LHF, la résistance à la compression chute significativement. A 3 jours, lorsque la teneur en LHF augmente, la porosité du béton augmente. A 90 jours, la réaction des LHF induit une diminution de la porosité capillaire et le réseau poreux devient plus fin. Ainsi, la perméabilité au gaz et la diffusion des ions chlore diminuent significativement. Les résultats montrent aussi que tous les bétons testés ont une profondeur de carbonatation similaire, après une année d'exposition au CO2. En effet, la diminution de la porosité, due à l'ajout des LHF est équilibrée par la diminution du pH, qui favorise la diffusion de CO 2

Periodic Solution for Nonlinear Second Order Differential Equation System

In this work, we investigate the periodic solutions for non-linear system of differential equationsby using the method of periodic solutions of ordinary differential equations which are given byA.M.Samoilenko. Additionally, the existence and uniqueness theorem have been proved for seconddifferential equations system by using Banach fixed point theore

Inverted Diamond-shaped Notched Substrate and Patch for High-frequency Interference on Ultra-wideband Antenna

Notches loaded on a patch antenna can affect significantly on ‎the antenna impedance matching. Therefore, notching technique is an efficient way to reduce ‎the electromagnetic interference with unwanted bands. In this paper, a ‎novel inverted diamond‏-‏shaped closed-end slot on a substrate and ‎vertex-fed printed hexagonal patch ultra‏-‏wideband antenna is proposed for high-frequency band rejection. This antenna is fed using ‎coplanar waveguide, and it is optimised by veering several patch ‎parameters which further improved the inter bandwidth at both the ‎lower and upper bands. However, the centre-notched band is shifted ‎from 6 GHz to 7.5 GHz by cutting the inverted diamond shape in a ‎special process. The developed ultra-wideband antenna is verified by ‎comparing the simulation results with the measurement results. The ‎measured results with a fractional bandwidth of 133% have a good ‎agreement with the simulation results 146%. Moreover, the measured radiation showed omnidirectional patterns‎

Characterization and Application of Aluminum Dross as Catalyst in Pyrolysis of Waste Cooking Oil

Aluminium dross, a waste material produced by dissolution of aluminum scrap, was characterized physically and chemically by various analysis techniques for a potential to be used as catalyst. Using catalyst from waste materials reduced the cost for synthesizing of new catalyst. An efficient catalyst derived from industrial solid waste was modified by acid washing for using in a pyrolysis of waste cooking oil. The modification of aluminum dross resulted in increased surface area (from 0.96 to 68.24 m2/g), acidity (from 315 to 748 µmol/g) and thermal stability. Pyrolysis waste cooking oil was used to test the performance of aluminum dross as catalyst before and after modification. The product analysis showed a better result than the unmodified material based on increased yield of bio-oil and improved selectivity.

Monomaniac revenge in Melville’s “Moby Dick” and Bronte’s “Wuthering Heights”

Revenge can be one of consequences of bad feeling towards others. This feeling of anger, hatred and prejudice could be based on traumatic visible or invisible experience. The level of that anger and hatred depends on the volume of damage caused by the action or judgment and, on other hand, it depends on man’s endurance and tolerance upon that action or judgment. Revenge can be individual or collective as well. Individually, it is driven personally as a reaction of other’s perceived harm when the individual desire is set to retaliate for bringing justice and satisfying his need. Collectively, most of ancient wars and conflicts were based on the concept of revenge which mostly brought collective devastation. This study will utilize rereading of the canonical texts; Moby Dick” by Herman Melville and “Wuthering Heights” by Emily Bronte, to make better understanding of the ‘monomaniac revenge’ by highlighting and analyzing the main characters in the two novels above ‘Ahab’ and ‘Heathcliff’, respectively, and their destructive revenge under the light of Psychological theory. Ahab was isolated from his family. Heathcliff was dismissed by his family. Later on they both lost their lives. Melville and Bronte prove that destructive revenge brings destructive results. The top focus of the study analysis will be on how Ahab and Heathcliff’s excessive desire of revenge develops and then brings them and people around to death

The association of socioeconomic status with positive mental well-being and mental health seeking attitude among undergraduate students: a cross-sectional study

Introduction: The future of our healthcare services highly depends on the current generation of health science students since they are the ones who will work in the healthcare setting. Ensuring their mental well-being is the utmost priority so that they can offer top-tier quality care and services to people in need. Thus, this study aimed to explore the prevalence of mental well-being and mental help-seeking attitude among undergraduate health science students and the impact of socioeconomic status (SES) towards both variables. Materials and method: A cross-sectional study was conducted via online survey among undergraduate health science students from six different kulliyyahs (N=364) at International Islamic University Malaysia, Kuantan Campus. The survey contained three main parts. The first part focused on the sociodemographic and socioeconomic status, the second part assessed participants’ mental well-being using the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) and the third part used the General Mental Help-seeking Attitude Scale (MHSAS) to analyse students’ mental help seeking attitude. Data were analysed using Statistical Package for the Social Sciences version 29.0. Descriptive analysis and inferential analysis were run to address the research objectives, which include independent sample t-test, one-way analysis of variance (ANOVA), Chi-Square, Pearson correlation and linear regression. Results: Only 7.1% of the students have positive mental well-being while about 44.8% scored positive mental help-seeking attitude. There were no significant differences between the mental well-being of students with all socioeconomic characteristics (p > 0.05). Additionally, One-way ANOVA tests showed a significant association between students’ year of study and mental help-seeking attitude (p = 0.029). Furthermore, Pearson correlation and linear regression tests revealed that both WEMWBS score and MHSAS score showed a positive correlation (p < 0.01). Conclusion: Future study is essential to find out the contributing factors, prevention and intervention that can be done to help the student in need

Impact of Tufa Stone Powder as a Partial Replacement of Aggregate on the Mechanical Performance and Durability of Repair Mortar

The rehabilitation and reconstruction works are usually performed with a view to conserving these landmarks and maintaining them culturally, architecturally and structurally. From this perspective, the mortars utilized in these repairs must be suitable, physiochemically and mechanically, to the ancient materials used in these buildings. Accordingly, it was proposed to evaluate tufa stone powder, a waste product of one of the most widely found stones in the Loire Valley in France, as an ingredient in repair-work mortar mixtures (M1, M2) through partially replacing the fine aggregate it contains with different amounts of this powder (37%, 42%) by weight of mix. Additionally, a third manufacturing mortar (M3) was utilized with both prepared mortars (M1, M2) for comparison with the tufa stone. The mechanical properties (including flexural, compressive and shear strengths, and ultrasonic pulse velocity) and the durability properties (total porosity, thermal dilation and conductivity, capillary absorption, and water and gas permeability) of the three mortars were examined in addition to those of the tufa stone. The results revealed that the prepared mortar, M2, (having lower binder content and a higher amount of substitution with tufa stone powder) has the lowest mechanical performance in comparison with the other mortars, indicating that this mortar is more supple and loose than the authentic tufa masonry. The thermal and durability properties are comparable to that of the tufa stone existent in ancient monuments. Consequently, the prepared mortar (M2) is the most appropriate mortar, for utilization in repairing old landmarks in the Loire Valley in France

Contribution Percentages of some Kinematical Variables of the Main Position in the Skills Performance Level of the Two-handed backhand Stroke for Tennis Players

يهدف البحث إلى التعرّف على نسب مساهمة بعض المتغيرات الكينماتيكية للوضع الرئيس في مستوى الأداء المهاري للضربة الخلفية بكلتا اليدين للاعبي التنس. افترض الباحث ونوجود نسب مساهمة لبعض المتغيرات الكينماتيكية في مستوى الأداء المهاري للضربة الخلفية بكلتا اليدين للاعبي التنس، وتكونت عينة البحث من(8) لاعبين من لاعبي التنس المتقدمين في محافظة نينوى، واستنتج الباحثون وجود نسب مساهمة معنوية لمتغيري (زاوية ميل الكتف، وارتفاع مركز ثقل كتلة الجسم) للوضع الرئيس في مستوى الأداء المهاري للضربة الخلفية بكلتا اليدين, وأوصى الباحثون بالتأكيد على مدربي التنس اعتماد المتغيرات الكينماتيكية التي أظهرت مساهمة معنوية لدورها في تطوير مهارة الضربة الخلفية بكلتا اليدين مع زيادة الاهتمام بالمتغيرات الكينماتيكية التي أفرزتها الدراسة.The study aimed to recognize the contribution&nbsp; rates of&nbsp; some Kinematical variables of&nbsp;&nbsp; main position in the Skillful performance level of the two-handed&nbsp; backhand stroke for tennis players, The researchers assumed that there are a contribution ratios of&nbsp; some Kinematical variables of main position in the skillful performance level of the two-handed backhand stroke for tennis players, research sample was consisted of (8) senior players in Ninevah province, the researchers concluded that the Kinematical variables (shoulders angle, height of the BMC) in the main position had a significant contribution in the skillful performance level of the two-handed backhand stroke, the researchers recommend to emphasis on the tennis coaches to adopt mechanical variables, which showed a significant contribution to its role in the development&nbsp; the two-handed backhand stroke skill and to Increase the interest in the Kinematical variables that&nbsp; produced by the study. &nbsp