Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene

Silicon dioxide (SiO2) is a common support for studying two-dimensional materials and creating devices from them. However, graphene conformation to SiO2 roughness worsens the electronic properties, whereas graphene deposited on flat terraces of insulating mica is free of ripples. This thesis solves key challenges in the use of mica to support mechanically exfoliated graphene. Methods of mica cleavage and graphene exfoliation, and settings for electron microscopy, atomic force microscopy (AFM) and Raman spectroscopy were developed. Vacuum annealing was compared for graphene samples of different thicknesses, down to a single layer. Pre- and post-annealing, graphene on mica provided defect-free graphene and no observable strain or doping. In contrast, graphene on SiO2 showed disorder before annealing. Annealing up to 300°C reduced the Raman defect peak but did not remove it. Above 300°C, the defect peak increased. Graphene on SiO2 appeared to become ‘invisible’ with AFM after annealing at 500°C, in line with previous observations with scanning electron microscopy. Other studies attributed this to the graphene being removed, but, here, using substrate markers, Raman spectroscopy and line-averaged AFM showed that the graphene was still present but had conformed to the underlying roughness of the SiO2 so well as to appear nearly invisible. Mica annealed at 400°C showed the formation of potassium carbonate particles following dehydroxylation of the mica surface at a temperature lower than previously reported. In addition, the graphene appeared to act as a mask, protecting the mica underneath it while the surrounding surface was removed at 500°C. Patterning and etching mica are essential to create location grids and etch trenches to suspend deposited materials. The first patterning lithography recipe for mica was established herein using electron-beam lithography. Finally, mechanically exfoliated graphene was successfully transferred to the patterned mica and studied

Expert-Generated and Auto-Generated Socratic Tutoring Systems For Code Comprehension

Programming skills are a vital part of many disciplines but can be challenging to teach and learn. Thus, the programming courses are considered difficult and a major stumbling block. To overcome these challenges, students could benefit from extensive individual support such as tutoring, but there are simply not enough qualified tutors available to meet rising demands.A potential solution is the development of intelligent tutoring systems (ITSs), which offer individualized, one-on-one instruction. Such systems can offer the support to make programming instruction more effective, scalable and reduce existing teachers\u27 workloads.This dissertation demonstrates how conversational ITSs and the Socratic method of teaching can improve a novice\u27s understanding of programming concepts and, in particular, the scaffolding of code comprehension processes. Furthermore, this work provides a novel method to automatically author a Socratic dialogue-based ITS. Indeed, two major outcomes of this work are a Socratic dialogue-based ITS and an automated dialogue authoring tool, which generates full Socratic dialogue from Java source code.The key objectives of this dissertation were, first, to determine whether the Socratic method would be effective at eliciting learners to engage in self-explanations with the help of the Socratic Tutor ITS and, second, to assess the quality of Socratic Author\u27s auto-generated tutorial dialogue. Thus, the work presented here sought to answer two main research questions: (1) can a Socratic ITS lead to improved code comprehension? and (2) to what extent can Socratic dialogue be generated automatically?In sum, this research helps establish a relationship between code comprehension and the use of the Socratic method in learning computer programming. Furthermore, the work introduces a novel approach for generating Socratic dialogue from source code with examples for the Java programming language. The auto-authoring tool could help teachers and ITS developers create tutorial dialogues automatically from Java code without requiring nondomain knowledge. To the best of our knowledge, no such auto-generation of tutorial dialogues from source code has been done before and thus constituting a premiere

The effect of leadership on corporate governance through the integration of corporate social responsibility : perspectives from the boards of directors and chief executive officers of the Libyan commercial banks

Corporate Governance (CG), Corporate Social Responsibility (CSR) and leadership have become such related concepts that each concept is a supplement and/or a complement to the other. CG, for example, has come to govern the principle-agent relationship and ensure the satisfaction of various stakeholders’ interests. CSR demands organisations to provide economic, social and environmental justice where they operate. Leadership is the ability of those with power to influence and guide followers to achieve common goals and simultaneously comprehend and respond bravely and constructively to the most critical economic, social and ecological challenges. Thus, once employed altogether effectively, these concepts establish healthy relationships with various stakeholders, gain competitiveness and generate corporate profits.However, these concepts have been recently under investigation in Libyan society. Scholars and private and public institutions have commenced examining the possible resolutions CG, CSR and leadership can arrange to alleviate the economic, social and environmental concerns the war has produced. Thus far, levels and efforts to apply CG codes have varied in Libyan companies. CSR is a new organisational culture that still designs its route within the Libyan commercial banks (LCBs). Leadership in the LCBs requires transformational and transactional styles to detach itself from any notion of dictatorship and autocratic traits. Therefore, this study tried to link the three concepts CG, CSR and leadership by exploring the impact of the board and executive leadership on CG framework to integrate CSR strategies in the LCBs.To achieve its goal, the study relied on three main questions to examine: First, to what extent does the board and executive leadership involve in the formation and application of CG structure? Second, to what extent does the board and executive leadership, through TSL and TFL styles, facilitate the application of CSR activities in the LCBs in light of the current Libyan crisis? Third, how does the board and executive leadership influence CG regulations to include CSR agendas in the LCBs to manage the issues caused by the current Libyan crisis? To answer these main questions, it was necessary to create a group of sub questions that investigated: First, the meanings, the current situations and challenges of CG, CSR and leadership? Second, the nature of relationship between CG and CSR in the LCBs? Third, the position of the TSL and TFL styles in the LCBs?In regard with the methodology, the study adopted the qualitative approach and conducted semi-structured interviews to collect the required data from 21 BMs and CEOs in 12 public and private LCBs. Then, the data was analysed by using grounded theory approach and thematic analysis method.The study provided some findings that answer the sub and main research questions starting with the sub question the findings showed that CG has narrow and wide definitions in the LCBs. Besides, the findings indicate that CSR is mainly encouraged and directed by religion and is centred on the notion of charity, and hardly touch upon achieving sustainable development. CG and CSR have a mutual relationship. Moreover, the findings demonstrate that Leadership features in the LCBs are under the influence of three factors, including the legacy of the previous regime, the Islamic culture and the Western perspective of leadership. Nonetheless, the leadership’s attempts to make economic and social changes seem difficult due to some challenges such as the weak of knowledge in regard with CG and CSR in the LCBs, the weak CG Enforcement system in addition to the Confusion between CSR and the notion of philanthropy, the transformation from traditional to Islamic banks and the impact of social and tribal culture. Concerning the main researcher questions, the findings revealed that the BoDs and CEOs involved in the establishment of the Libyan Corporate governance code (LCGC) by compromising the CG international guidelines with national laws and regulations, in addition to their crucial role in the application and development of CG policies within their banks. The findings also indicated that BoDs and CEOs applied TFL and TSL styles. Both styles work together as continuum to enable the implementation of CSR activities within and outside the banks. Finally, the finding confirmed that the BoDs and CEOs influence the CG regulations to include the CSR practices in the LCBs to meet the interests of both shareholders and other stakeholders.The study has some limitations, including the lack of literature regarding to the concepts of CG, CSR and leadership in Libya. Additionally, the study did not include leaders from the middle and lower management and also did not cover other stakeholders’ entities. Moreover, this study did not distinguish the differences between the public banks from the private banks. Female participants are absent in this research due to engendered Libyan environment. Finally, the Libyan crisis experienced during the conduct of this research influenced, somehow, the findings of this research

An investigation of the two phase flow and force characteristics of a safety valve

The two phase flow of air and water is studied in a safety relief valve commonly used in the industrial refrigeration industry. In some blowdown conditions a valve which has been specified for gas only operation may encounter flows which include liquid droplets, these having been entrained from upstream processes. Of particular interest is the operation under two phase flow conditions which will be dominated by the altered flow capacity and forces acting on the valve. To examine these effects the characteristics of the flow through the valve and the forces acting on the valve disc have been examined for an air water mixtures for a range of pressures, 5-14 bar, and a wide range of gas mass fractions for various different opening positions. These characteristics determine the capacity of the valve to control pressure, the sizing of the spring and the dynamics of the valve during operation. The data on such effects for safety valves is very limited and here we show the trends that result from the introduction of two phase flow mixtures and reflect on the limited previous work in the literature that is available. The tested range of conditions the results indicate that the flow and force characteristics are influenced by liquid injection with a significant influence on the flowrate. The disc forces resulting from the two phase impacts show a small but notable effect from liquid mass fractions. This is in contrast to previous limited data found in the literature

Saudi Arabia and its Gulf Co-operation Council neighbours : a study in international boundary management.

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN042872 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Multimodal interventions to enhance adherence to secondary preventive medication after stroke: a systematic review and meta-analyses

Summary: Introduction: Nonadherence to secondary preventative medications after stroke is common and is associated with poor outcomes. Numerous strategies exist to promote adherence. We performed a systematic review and meta-analysis to describe the efficacy of strategies to improve adherence to stroke secondary prevention. Methods: We created a sensitive search strategy and searched multiple electronic databases (MEDLINE, EMBASE, CINAHL, PsycINFO, CENTRAL, and Web of Knowledge) for studies of interventions that aimed to enhance adherence to secondary preventative medication after stroke. We assessed quality of included studies using the Cochrane tool for assessing risk of bias. We performed narrative review and performed meta-analysis where data allowed. Results: From 12,237 titles, we included seventeen studies in our review. Eleven studies were considered to have high risk of bias, 3 with unclear risk, and 3 of low risk. Meta-analysis of available data suggested that these interventions improved adherence to individual medication classes (blood pressure-lowering drugs – OR, 2.21; 95% CI (1.63, 2.98), [P < 0.001], lipid-lowering drugs – OR, 2.11; 95% CI (1.00, 4.46), [P = 0.049], and antithrombotic drugs – OR, 2.32; 95% CI (1.18, 4.56, [P = 0.014]) but did not improve adherence to an overall secondary preventative medication regimen (OR, 1.96; 95% CI (0.50, 7.67), [P = 0.332]). Conclusion: Interventions can lead to improvement in adherence to secondary preventative medication after stroke. However, existing data is limited as several interventions, duration of follow-up, and various definitions were used. These findings need to be interpreted with caution

A Proposal for Developing the Performance of Intermediate Second-Grade Students in Science Tests in Trends in International Mathematics & Science Study (TIMSS)

This study aimed at identifying the reasons responsible for the low performance of the students of the second intermediate grade in science’s tests in the Trends in International Mathematics and Science Study (TIMSS). It also intends to provide a proposal for developing the performance of the students of the second intermediate grade in science tests in TIMSS. The study adopts the descriptive methodology. To achieve the results of the study, a questionnaire was prepared to identify the reasons responsible for the low performance of the students of the second intermediate grade in science tests in TIMSS. It consisted of three-dimension i.e. course content, student, and teacher & teaching performance. The results of the study showed that the study sample members are agreed with a high degree of all items of the questionnaire. Considering these results, the study provided a proposal to develop the performance of the students of the second intermediate grade in science tests in TIMSS. The proposal also consists of the same dimensions i.e. course content, student and teacher & teaching performance. The study recommends benefiting from the proposal to develop the performance of students of the second intermediate grade in science tests in TIMSS. It also suggests conducting future studies aimed at comparing some variables related to science education and learning in advanced-performing countries and the Kingdom of Saudi Arabia

Detecting A-Series Ganglioside Expression Profile Changes During Microglial Activation

With aging, our brains become more susceptible to disease and injury. Different regions of the brain have differing levels of vulnerability to stress and injury, and this brain region-dependent variability to vulnerability could be partly explained by the existence of glycosphingolipids within the cell’s plasma membrane called gangliosides. Gangliosides are expressed predominantly within the brain and play various roles within the central nervous system including neural repair, cell survival, and neurodegeneration. Our laboratory has demonstrated that gangliosides can shift their composition from GM1 back to GM2 and GM3 following stroke in mice and rats indicating a role for simple gangliosides in the neurodegenerative process and this shift may be part of a neuro-inflammatory cascade. However, to date, ganglioside analysis in microglia cells has not yet been done. Based on the literature and preliminary studies conducted in our laboratory, we hypothesized that GM1, GM2 and GM3 levels will change during microglia activation. BV2 cells were cultured and cells were treated with lipopolysaccharide (LPS) and interleukin 4 (IL-4) to induce M1 and M2 activation, respectively. Liquid chromatography electrospray ionization mass spectrometry LC-ESI-MS was used to quantify ganglioside levels following activation, and immunofluorescence was used to stain for GM1, GM2 and GM3 gangliosides. RT-qPCR was performed to verify what phenotypes were activated in response to observed changes in gangliosides. Our results showed a significant increase in GM1, GM2 and GM3 gangliosides in M1 BV2 cells while no change was observed in the M2 phenotype. RT-qPCR results showed a significant peak in M1 markers at 24 h following LPS while M2 markers peaked at 8 h following IL-4 exposure. Our in vitro results suggest that M1 phenotype could be selectively targeted to understand ganglioside changes following injury and that M1 microglia can be the source of the transient increase in GM1, GM2 and GM3 found in animal models of neurodegeneratio