Synthesis of Some Pyridinone Nucleoside Analogues as Antitumor Agents

Abstract 3-Deazapyrimidine nucleosides have been shown to exhibit great potential as pro drug for use in medicine especially as antagonists to cancer tumors and the HIV-virus. Recent research has focused on the design, synthesis and characterization of novel nucleoside analogues. Fluoropyridinone and their corresponding nucleoside derivatives have been synthesized and characterized to induce the activity against tumors. 4, 6-diaryl-3-cyano-2(1H)-pyridinones (82a-i) and their nucleosides were prepared. A trifluoromethyl group was introduced into the pyridinone ring system to study its effect on different tumor cells. The glycoside analogues (83a-e, 85a-e, 87a-e and 88a-d) have been synthesized in good yield via the reaction between pyridinone derivatives and an activated hexapyranosyl sugar to give N-nucleosides (83a-e, 85a-e, 87a-e and 88a-d) as the sole product. In our biological screening, it was found that the fluorine and trifluoromethyl derivatives of the pyridine ring enhance the biological activity. Moreover, the novel non-nucleoside derivatives (89a-d) are found to be more active than the corresponding N-nucleosides. This enhancement in biological properties is due to the presence of the fluorine groups on the pyridine ring. Computer aided Quantum Mechanics (QM) calculations using density functional theory (DFT) were used to study the reactivity of 3-deazapyrimidines with activated sugar molecules. Gaussian 98 was employed for the calculation of geometries and energies. Charge density gas phase calculations were performed at the B3LYP level with the 6-31G basis set. The data obtained from QM calculations supports our experimental results by showing higher charge density on the pyridine N-atom than on the oxygen atom at C-2. HOMO-LUMO charge density studies of the isolated compounds are fully consistent with the spectroscopic results. Structure-Activity Relationships (SAR) of nucleosides (83a-e, 85a-e, 87a-e and 88a-d) and other non-nucleosides (89a-d) showed an interesting biological activity. Structure-activity relationships studies of 3-deazapyrimidine derivatives were used to determine the parts of the structure that are responsible for its biological activity and its side effects according to the nature of the substituents. The results have shown that 2-thiophene at the 4-position has the highest activity among all analogues. In addition, the aryl group at the 6-position has shown similar activities. For example, 4-(thiophen-2-yl)-6-phenyl-3-cyano-2(1H)-pyridinones (82d) and 4-(thiophen-2-yl)-6-(p-chlorophenyl)-3-cyano-2(1H)-pyridinones (82e) have shown the same activity at lower and higher concentrations. This result indicates that aryl groups at the 6-position have the same effects, based on the results obtained from biological screening. Meanwhile, nucleosides containing the glucopyranosyl ring system showed higher activity than the galactose isomer. For example, compounds (83a-e) have shown better activity than the corresponding galactoside analogues (87a-e). All free nucleosides showed higher activity due to the solubility factor, where the low soluble acetylated derivatives showed good activities. 2-Thiophene present at the 4-position showed promising biological activity in both nucleosides and non-nucleosides. Meanwhile, more interesting results were obtained from the non-nucleoside analogues (89a-d). SAR has explained these results as follows: The solubility factor might not be the dominant factor because even the low soluble non-nucleoside (89a) was found to have the highest potential activity

Self–assessment in EFL Grammar Classroom: A Study of EFL Learners at the Centre for Languages and Translation, Ibb University

The present study investigated the implementation of self-assessment in EFL grammar classroom to identify the attitudes of EFL learners at the Centre for Languages and Translation, Ibb University towards self-assessment, their perceptions of the advantages of self-assessment, and the problems or difficulties that EFL learners may face while carrying out self-assessment activities. To collect data, the researcher used three instruments: a questionnaire, a structured interview, and a focus group discussion. The questionnaire was administered to (85) EFL learners. Using the stratified sampling technique, the researcher selected randomly (14) learners for the interviews and (21) learners to participate in the focus group discussions. The findings of the study indicated that EFL learners perceive the benefits of self-assessment and have positive attitudes towards it. The study reported that the learners did not have any problems or difficulties while carrying out self-assessment activities, which may be due to the nature of the self-assessment technique and activities used and the sufficient training and guidance that the EFL learners received. The study showed that there were statistically significant differences in the mean scores of the learners’ responses according to the frequency of doing self-assessment activities, but not according to the variables Gender and Proficiency Level. As the study indicated that self-assessment is helpful and has several advantages for EFL learners and that EFL learners have positive attitudes towards it, the researcher recommended that EFL teachers should think about integrating self-assessment into their classrooms

Using Alternative Assessment to Assess Undergraduate EFL Students at Yemeni Universities: Challenges from the Perspectives of Faculty

The present study aimed at investigating alternative assessment (AA) within the Yemeni university EFL classrooms in terms of identifying the challenges of using AA to assess undergraduate EFL students from the perspectives of the faculty. Data were collected, through a questionnaire, from (66) lecturers and professors of different ranks who teach EFL at the collegiate level in two Yemeni public universities and one national university. The results of the study indicated that faculty members of English departments at Yemeni universities face some challenges of using AA to assess undergraduate EFL students. These challenges belong to various factors, including the instructional environment, the students, the management of Yemeni universities, the faculty members, or the nature of AA. Statistically significant differences were found in the mean scores according to years of experience variable between respondents with less than 5 years and those with 5-10 years of experience in favor of those with less than 5 years of experience, but not according to the type of university, gender, and specialization variables. Accordingly, some recommendations were given to address the identified challenges, which might lead to a better implementation of AA in Yemeni university EFL classrooms

THE IMPACT OF CLASSROOM DENSITY ON TEACHERS\u27 PERFORMANCE AND STUDENTS\u27 ACHIEVEMENT IN AL-AIN SCHOOLS : PERSPECTIVE OF TEACHERS AND STUDENTS

This quantitative study aimed at investigating the students\u27 and teachers\u27 perceptions about the effects of classroom density on teacher\u27s performance and student\u27s achievement in Al-Ain Schools. The study addressed the two research questions (a). To what extent classroom density impact teacher\u27s performance in Al-Ain Cycle Three Schools? (b) To what extent classroom density impact students\u27 achievement in Al-Ain Cycle Three Schools? To have an in-depth understanding of whether class density impacted teaching and learning students, the causal comparative study design was conducted to collect data via two questionnaires; one for teachers, and the other for grade 12 students. The findings of this study revealed that classroom density impacted both the teacher\u27s performance and students\u27 achievement negatively according to the perceptions of most teachers and students. The study grants some insights that help schools and all stakeholders improve teaching and learning by reducing the classroom density. It is recommended to take into consideration the classroom density and set rules that decrease the classroom density; set clear rules to the importance of availability of multifunctional halls and using multifunctional furniture, deliver non-traditional lessons and integrate technology in teaching and learning in classrooms in Al-Ain schools. The study is limited to grade twelve students in one academic year 2014 in one educational zone. It included one Cycle three school teachers

Analysis of Jamming Attacks on Wireless Sensor Networks

Wireless Sensor Network (WSN) is a wireless-oriented form of communication largely used for outdoor applications, such as environmental monitoring and military surveillance. Therefore, a jamming attack is one of the denial of service attacks (DOS) that may take place by jamming the communication channel, making communication between genuine sensor nodes difficult or even impossible. Several studies have been carried out to develop countermeasures against jamming attacks, utilising parameters such as Packet Delivery Ratio (PDR), Packet Send Ratio (PSR), Received Signal Strength Indication (RSSI) and Clear Channel Assessment (CCA). The accuracy of the parameters used is very important for developing successful countermeasures against jamming attacks. Consequently, the focus in this study is to examine the effect of a jamming attack that was generated by one or more wireless sensor network nodes on PDR, PSR and RSSI, and look at the enhancements that can be made on Packet Delivery Ratio by altering the value of CCA on sender nodes. The experiment was performed using XBee RF and K-mote devices configured as jammers by disabling the CSMA protocol. It was performed in a non-isolated room in order to emulate a real-life environment. Two scenarios were carried out in this study. The first scenario aimed to study RSSI, PSR and PDR values with a fixed CCA value, and the second scenario studied the effect of CCA on PDR value. The experiment showed that the RSSI value measured by XBee RF inflated in the presence of noise. This fact has to be considered when RSSI is utilised in jamming attack counter measures. Further, it has been observed that the PDR value is distressed by jamming because genuine packets collide with jammers’ packets and increase the power of the sent packets without considering that the distance will not be enough to enhance the PDR value. This study demonstrates that changing the CCA threshold value on the XBee RF module influences the Packet Delivery Ratio (PDR) value in the presence of jamming

Total Quality Management and its Impact on Establishing an Effective Learning Environment in Abu-Dhabi High Schools

The issue of quality has gained attention in recent years and has placed the education system under ongoing reform. This has urged educational institutions to improve the quality of education delivered. Based on the relevant literature, this study identified the main features of Total Quality Management (TQM) as well as the features of an effective learning environment. TQM philosophy and its implementation in education provide the theoretical background for this work. The purpose of this paper was to investigate TQM practices and to examine its impact on the learning environment in secondary schools in Abu Dhabi Emirate, in UAE. This paper focuses on the links between (TQM) and the effectiveness of the learning environment. In addition, this paper provides a description of total quality in education. Furthermore, the literature shows how it can be successfully implemented through the leadership of schools. This is a mixed method study using a cluster sample survey to collect data from both academic and administrative staff in (34) schools in three educational zones Abu Dhabi, Al Ain and Western Region. The instrument relied on a Likert-scaled questionnaire which included the main elements of effective learning environments as well as all the key components of TQM theory. The data analysis involved descriptive statistics, T-tests while the relationship between TQM and the learning environment were examined through analysis of variance (ANOVA). Ln addition, open-ended question responses were categorized in common themes then they were computed to find out the percentage and the frequency. The participants\u27 responses identified elements necessary for an effective learning environment. The findings indicated a significant application of TQM in Abu Dhabi Emirate with comparative differences in the three educational zones. Furthermore, the data revealed the learning environment is effective, along with the key features that determine this. Consequently this research established a correlation between the two variables, TQM and an effective learning environment

A FRAMEWORK FOR GUIDING THE BRIEFING PROCESS IN PUBLIC-PRIVATE PARTNERSHIPS IN THE UAE CONSTRUCTION INDUSTRY

Public-Private Partnership (PPP) is a procurement method that employs a long-term contractual arrangement between public and private sectors with the intention of developing a public facility. A PPP brief must supply information that not only particularizes the project requirements but also specifies its program, risk management, expected performance output and payment mechanism. Many challenges currently face the briefing process of PPP projects in the UAE. A uniform briefing process has not been agreed, because there is no unified tender law or PPP procurement process in the country. The main aim of this research is to develop a framework for guiding the development of PPP briefing stage in the UAE construction industry. To this end, a process framework for PPP briefing with special reference to UAE construction projects was developed first, on the basis of an intensive literature review and analysis of case studies. This framework was validated through interviews with PPP experts and professionals in the UAE. Following this, the Critical Success Factors (CSFs) in PPP briefing, with special reference to UAE construction projects, were investigated and identified through a literature review, expert interviews, and a questionnaire survey. This step led to developing another framework for CSFs in PPP briefing with special reference to UAE construction projects. With these in mind, CSFs were modelled to develop a Decision Support System (DSS) the main aim of which was to guide the of the briefing stage for PPP projects in the UAE. Its main objectives focused on assessing the readiness of public and private organizations for successful briefing development, highlighting areas for improvements and helping to develop action plans to improve the briefing process. In order to validate the developed model and assess its performance as a decision-making tool, two mega construction projects (real case studies) were assessed by means of the proposed model. The outputs of the implemented evaluation validated the major aspects of this model and its developed prototype, together with its performance for its stated purpose

Climate-Resilient UAVs: Enhancing Energy-Efficient B5G Communication in Harsh Environments

This paper explores the crucial role of Unmanned Aerial Vehicles (UAVs) in advancing Beyond Fifth Generation (B5G) communication networks, especially in adverse weather conditions like rain, fog, and snow. The study investigates the synergy between climate-resilient UAVs and energy-efficient B5G communication. Key findings include the impact of weather elements on UAV coverage and communication dynamics. The research demonstrates significant enhancements in energy efficiency, reduced interference, increased data transmission rates, and optimal channel gain under various weather conditions. Overall, this paper emphasizes the potential of climate-resilient UAVs to improve energy-efficient B5G communication and highlights technology's role in mitigating climate change's impact on communication systems, promoting sustainability and resilience

Review Paper on Quantum Technology for Use with Optical Fiber

As in our day to day life communication has become very vital. Its importance has increased so much, that it has become vital for our survival. Moreover, information is dependent on physical system upon which it is processed and by which is carried. If we talk about optical communication, it can be thought as form of colored smoke signals. Today's we are covering our planet in a network of optical fibers. In this paper, our research is based on quantum technology where each particle is described by a quantum wave function characterizing the state of the system. The ability to generate, manipulate, transmit and detect a single or very few photon(s) may open new routes that can trigger a completely new generation of communication systems. Scientists at Dutch University have conducted an experiment that proves one of the most radical claims of quantum theory called “entanglement”, which Einstein famously rejected. This is a property in which objects separated by great distance can interact and instantaneously affect each other’s behavior. The experiment also proves subatomic particles do not take form until they are observed. It shows that quantum technologies can address two of the more challenging problems communication engineers face nowadays: capacity and security. Indeed, by radically decreasing the number of photons used to encode each bit of information, we can more efficiently explore the full capacity to carry information of optical fibers

Effect of Procedural Justice on Organizational Commitment:Evidence from Pakistan

Procedural justice and organizational commitment are extensively studied factors paying significantly in organizational success. The objective of this study was to measure the effect of procedural justice on organizational commitment. For the said purpose primary data have been collected from 120 academicians of Gomal University, Dera Ismail Khan, Khyber Pakhtoonkhwa, Pakistan. A likert type questionnaire was used as a tool for data collection. The data was collected through questionnaire and put in the data matrix on SPSS 17. The regression was used to measure the effect of procedural Justice on organizational commitment. The results indicate that procedural justice has positive significant influence on organizational commitment. Keywords: Procedural Justice, Organizational Commitment, and Academicians, Pakistan.