230 research outputs found
The analysis of the functional role of the cancer-associated, chromosomal breakpoint binding protein Translin in maintaining genome stability.
Teaching Arabic through communicative language teaching approaches informed by new understandings of literacy in primary schools in Tabuk, Saudi Arabia
This thesis seeks to document the perspectives of 24 male primary educators of the Arabic language on teaching Arabic through communicative language teaching (CLT) approaches informed by the new literacy theory (NLT) in Saudi Arabia (Tabuk). In Saudi Arabia, there is little focus on the importance of communication skills in using Standard Arabic, whether in conversation, listening and speaking. This study aims to fill the gap in the research literature on Arabic language teaching in primary education, drawing on the NLT. Arabic is a global language and this study has international significance as the findings will inform the teaching of Arabic as a first and additional language. Therefore, this study investigates the usage of CLT approaches into the teaching of Arabic through the use of various activities that are contextual and meaningful.
The focus of this study is on language in relation to listening, speaking, viewing, reading, writing, critiquing and creating in purposeful contexts. It utilises a mixed method mainly drown on qualitative research methods to examine five case study sites (government primary schools in urban Tabuk) to investigate the use of technology in Standard Arabic Teaching using CLT approaches. Furthermore, the study examines the use of a contemporary curriculum in order to contrast it to traditional approaches. Data was initially gathered with a survey to collect demographic data about the study and its subjects. Participants were then interviewed to obtain deeper and more detailed information. The study covered five schools and four supervisors.
Moreover, this study draws on connectivism theory, which presents a concept of information being presented via complex networks that enable the educational process to occur. In the connectivism theory, learning occurs via networks through a mix of technological and social interactions.
The findings indicate that there is a lack of understanding the NLT, and tensions between traditional and contemporary curriculum supporters exist. The professional development and academic preparation (pre-service) received by students in colleges and universities was one of the most prominent findings in this study, because it shows a weakness in the preparation that student teachers receive in educational institutions. In addition, the findings highlight issues in providing information technology (IT), access to the use of technology, leadership and change.
In conclusion, this study revealed that curriculum change in Saudi Arabia is a controversial topic in relation to Saudi societal ideologies. In particular, the study highlighted that curriculum change, leadership, contemporary views of literacy learning and Arabic education are as important as other issues such as religion, Arabic identity, resistance to change and Westernisation. Hence, this study points to the significance of professional development in curriculum change where teachers, principals, educators, curriculum designers, policy makers and parents are involved in the development of curriculum in order to provide high quality education for their children
Gas-Gas Separation Using a Hollow Fiber Membrane
Computational fluid dynamics simulations are conducted for laminar steady asymmetric flows within a hollow fiber membrane unit. The goal is to study the effect of the porous layer of a hollow fiber membrane (HFM) on the flow regimes and thus on the separation process. The mixture of CH4 and CO2 is studied with the goal of separating CO2 from CH4. The hollow fiber membrane consists of a circular channel bounded by a supporting porous layer. Outer surface of the tubular pipe is bounded by a selective membrane. The Navier-Stokes equation, Darcy\u27s law, and the species transport equations are solved for various values of permeability of the porous medium and Reynolds numbers. The mass flux of each species passing through the membrane is determined based on the local partial pressure, the concentration of each species, the permeability and the membrane selectivity. The porous layer influences the flow field in the open channel strongly. With increasing resistance the flow rate through the porous medium decreases. The flow rate through the open channel increases as the resistance of the porous layer is increased. The presence of the porous layer results in the reduction of mass flux of both CH4 and CO2 passing through the membrane. The Sherwood number is reduced at all Re as the resistance of the porous layer is increased. The increased resistance of the porous layer also causes an increase in the pressure drop in the hollow fiber membrane module. The present study proves that the porous layer should be included in modeling of hollow fiber membrane systems
Peganum Harmala plant as an adsorbent for the removal of Copper(II) ions from water
Batch removal of Cu(II) from water by powdered seeds of Peganum Harmala has been investigated in this research. The Peganum Harmala seeds were collected after which they have been beaten slowly, separated and then cleaned using a sieve. The prepared sorption is characterized by FT-IR. Batch adsorption studies have been undertaken in 100 ml Erlenmeyer flasks, inside an incubator container. The main process parameters that are considered are pH, contact time, Cu(II) concentration, the Adsorbent dose effect and reaction temperature effect. Cu(II) is measured at a wavelength of 620 nm, using a UV-vis spectrophotometer. The result evidence that the maximum removal of Cu(II) is observed at pH 6.2, with the pH over 6.2 result to participate the copper hydroxide. Clearly, the uptake process of the Cu(II) ion occurres very swiftly from the outset of the experiments during the first 15 min, after which there is a low decrease until 40 min, when maximum adsorption of Cu(II) ion onto Peganum Harmala is observed. An increased Cu(II) ions removal percentage occurres with increasing dose of adsorbents, increasing from 0.2 to 0.6 g followed by an increased percentage removal from 63.50% to 66.02%. Subsequently, the removal of Cu(II) ions decline, with an increased dose to 1g. Langmuir adsorption isotherm is more appropriate than the Freundlich adsorption isotherm, while the pseudo second-order reaction model is suitable for adsorption of the Copper ion onto the active centers of the Peganum Harmala surface compared with the pseudo first-order model
GRAPHICAL ONE-TIME PASSWORD AUTHENTICATION
Complying with a security policy often requires users to create long and complex passwords to protect their accounts. However, remembering such passwords appears difficult for many and may lead to insecure practices, such as choosing weak passwords or writing them down. One-Time Passwords (OTPs) aim to overcome such problems; however, most implemented OTP techniques require special hardware, which not only adds costs, but also raises issues regarding availability. This type of authentication mechanism is mostly adopted by online banking systems to secure their clients’ accounts. However, carrying around authentication tokens was found to be an inconvenient experience for many customers. Not only the inconvenience, but if the token was unavailable, for any reason, this would prevent customers from accessing their accounts securely.
In contrast, there is the potential to use graphical passwords as an alternative authentication mechanism designed to aid memorability and ease of use. The idea of this research is to combine the usability of recognition-based and draw-based graphical passwords with the security of OTP. A new multi-level user-authentication solution known as: Graphical One-Time Password (GOTPass) was proposed and empirically evaluated in terms of usability and security aspects.
The usability experiment was conducted during three separate sessions, which took place over five weeks, to assess the efficiency, effectiveness, memorability and user satisfaction of the new scheme. The results showed that users were able to easily create and enter their credentials as well as remember them over time. Eighty-one participants carried out a total of 1,302 login attempts with a 93% success rate and an average login time of 24.5 seconds.
With regard to the security evaluation, the research simulated three common types of graphical password attacks (guessing, intersection, and shoulder-surfing). The participants’ task was to act as attackers to try to break into the system. The GOTPass scheme showed a high resistance capability against the attacks, as only 3.3% of the 690 total attempts succeeded in compromising the system.King Abdulaziz City for Science and Technolog
Removal of cobalt (II) ions from aqueous solution by Peganum Harmala seeds
The batch extraction of cobalt [Co(II)] ions from an aqueous solution, utilizing the seeds of Peganum harmala has been evaluated in this study. After gathering Peganum harmala, the plants are beaten to separate the seeds, after which the seed undergo a fine filtration process to remove any debris. The prepared adsorption material is defined by Fourier transform infrared spectroscopy (FTIR). The adsorption process is conducted an incubator in 50 mL flasks. The studied process variables included pH, contact time, Co(II) concentration, adsorbent dose and reaction temperature. Co(II) is assessed with the use of a UV-vis spectrophotometer at a wavelength of 512 nm. Optimal Co(II) removal is noted at a pH of 6; increased alkalinity resulted in the generation of cobalt hydroxide. When contact time is increased from 5 to 40 min, the removal of Co(II) ions increased from 8 to 88%. This represented the maximum adsorption of Co(II) into Peganum harmala. After this time, equilibrium was achieved, with no further Co(II) extraction occurring. The higher the dose of adsorbent, the higher the degree of Co(II) ion removal; increasing the adsorbent from 0.1 to 0.4g/L result in an increase in extraction from 60 to 84%. A larger dose of adsorbent, up to 0.5 g/L, diminished further Co(II) ion subtraction. The Langmuir adsorption isotherm show a superior model fit compared with the Freundlich isotherm
Multidecker assemblies from Porphyrin and Phthalocyanine derivatives
The work set out in this thesis focuses on the synthesis and investigations of linked heteroleptic triple deckers (TD) based on porphyrin-phthalocyanine-porphyrin analogues. They are interesting materials because of the potential applications of lanthanide-bridged triple and double deckers in molecular devices. Research on their synthesis has taken huge steps forward in recent years. They also have low oxidation potentials, as well as reversible electrochemistry. Such remarkable features give these complexes great potential for their use in several applications, for example, molecular magnets, multibit molecular information storage, sensors, nonlinear optical materials, nanomaterials and field effect transistors that cannot be achieved by their mono- metallic macrocycle counterparts. A number of multidecker systems have previously been synthesised by Cammidge group.
Firstly, this current research focuses on phthalocyanine and related macrocycles by attempting to synthesise unsymmetrical systems that could be inserted in a triple-decker formed by the reaction with linked porphyrins, with a view to preparing higher order structures through linking this unsymmetrical central macrocycle. However, insertion of the selected phthalocyanines proved challenging. Triple decker structures were formed and isolated, but characterisation proved challenging, and the spectroscopic results could not prove that simple porphyrin-phthalocyanine-porphyrin were formed.
Secondly, we switched to the synthesis of alternative macrocycles such as tetrabenzotriazaporphyrins (TBTAPs) which are hybrid structures that lie between the parent phthalocyanine and tetrabenzoporphyrin macrocylces. Importantly, the meso carbon opens up a variety of possibilities in the TBTAPs. The synthesis of triple deckers with different meso- substituted TBTAPs has been achieved but the spectroscopic characterisation was much more complicated as compared to the previous symmetric phthalocyanine derivatives. Rotation is hindered (NMR) in these cases. Finally, the decision was taken to investigate a different class of multichromophore assemblies. We aimed to synthesise a compound that bears a more rigid element to the bridge that could be further functionalised or dimerised. Triple deckers of compounds that bear a more rigid element (such as benzene and porphyrin) to the bridge were successfully synthesised using the developed procedure for the selective formation of linked closed triple deckers, and overall, this appears to be a very promising strategy for building up more complex arrays of TDs
Ruthenium Catalyst for Epoxidation Reaction
The role of ruthenium as a heterogeneous catalyst for epoxidation reaction has not been investigated extensively. Therefore, the purpose of this chapter is to provide overview of the epoxidation of alkene using ruthenium catalysts. The chapter is divided into two main sections. The first section is about epoxidation of alkene using supported ruthenium catalysts, while the second using ruthenium complexes (homogenous catalysts)
Peganum Harmala plant as an adsorbent for the removal of Copper(II) ions from water
163-171Batch removal of Cu(II) from water by powdered seeds of Peganum Harmala has been investigated in this research. The Peganum Harmala seeds were collected after which they have been beaten slowly, separated and then cleaned using a sieve. The prepared sorption is characterized by FT-IR. Batch adsorption studies have been undertaken in 100 ml Erlenmeyer flasks, inside an incubator container. The main process parameters that are considered are pH, contact time, Cu(II) concentration, the Adsorbent dose effect and reaction temperature effect. Cu(II) is measured at a wavelength of 620 nm, using a UV-vis spectrophotometer. The result evidence that the maximum removal of Cu(II) is observed at pH 6.2, with the pH over 6.2 result to participate the copper hydroxide. Clearly, the uptake process of the Cu(II) ion occurres very swiftly from the outset of the experiments during the first 15 min, after which there is a low decrease until 40 min, when maximum adsorption of Cu(II) ion onto Peganum Harmala is observed. An increased Cu(II) ions removal percentage occurres with increasing dose of adsorbents, increasing from 0.2 to 0.6 g followed by an increased percentage removal from 63.50% to 66.02%. Subsequently, the removal of Cu(II) ions decline, with an increased dose to 1g. Langmuir adsorption isotherm is more appropriate than the Freundlich adsorption isotherm, while the pseudo second-order reaction model is suitable for adsorption of the Copper ion onto the active centers of the Peganum Harmala surface compared with the pseudo first-order model
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