Search results

This study aims to examine the role of institutional investors in improving board diversity for the companies in which they invest (investee companies) using evidence from corporate board characteristics across the globe. Additionally, this study also investigates the association between institutional investors and board diversity under various institutional settings, including varying economic conditions (pre-crisis, crisis and post-crisis), legal systems and ownership structures.

Using a sample collected from 15 countries for the period 2006 to 2012, the paper uses panel data analysis to examine the association between institutional investors and board diversity.

The study provides evidence that institutional investors do not promote board diversity and show that in general there is no association between institutional ownership and various board diversity attributes such as gender, age, nationality and education. However, the study finds that institutional investors are positively associated with the educational diversity of boards during times of crisis and are negatively associated with board age diversity during pre-crisis and post-crisis periods. Furthermore, while in common law countries institutional investors are found to be negatively associated with board age diversity, they do not influence board diversity outcomes (i.e. gender, age, nationality and education) in civil law countries. The results also show that the associations between institutional investors and board diversity are mixed and insignificant according to different ownership structures (family and non-family owned firms). The main findings of the study are robust and apply to various estimation methods.

This study provides a unique perspective on the impact of institutional investors on board diversity using a sample collected from 15 countries. Furthermore, the study provides an insight that the institutional settings should be considered when investigating the activism of institutional investors in improving governance practices.

In smart cities striving for innovation, development, and prosperity, hydrogen offers a promising path for decarbonization. However, its effective integration into the evolving energy landscape requires understanding regional intricacies and identifying areas for improvement. This chapter examines hydrogen transport from production to utilization, evaluating technologies’ pros, cons, and process equations and using Analytic Hierarchy Process (AHP) as a Multi-Criteria Decision-Making (MCDM) tool to assess these technologies based on multiple criteria. It also explores barriers and opportunities in hydrogen transport within the 21st-century energy transition, providing insights for overcoming challenges. Evaluation criteria for hydrogen transport technologies were ranked by relative importance, with energy efficiency topping the list, followed by energy density, infrastructure requirements, cost, range, and flexibility. Safety, technological maturity, scalability, and compatibility with existing infrastructure received lower weights. Hydrogen transport technologies were categorized into three performance levels: low, medium, and high. Hydrogen tube trailers ranked lowest, while chemical hydrides, hydrail, liquid organic hydrogen carriers, hydrogen pipelines, and hydrogen blending exhibited moderate performance. Compressed hydrogen gas, liquid hydrogen, ammonia carriers, and hydrogen fueling stations demonstrated the highest performance. The proposed framework is crucial for next-gen smart cities, cutting emissions, boosting growth, and speeding up development with a strong hydrogen infrastructure. This makes the region a sustainable tech leader, improving air quality and well-being. Aligned with Gulf Region goals, it is key for smart cities. Policymakers, industries, and researchers can use these insights to overcome barriers and seize hydrogen transport tech opportunities.

The purpose of this paper is to study the effect of the relative velocity between ship hull and seawater on the rate of zinc consumption and degree of cathodic protection during sacrificial cathodic protection of steel hulls using zinc anodes.

The rate of zinc consumption under different relative velocities was determined by the loss in weight technique while the degree of cathodic protection of the ship hull at different distances from the anode was determined by measuring the cathode potential of the hull cathode against a silver/silver chloride reference electrode.

Within the present range of conditions, the rate of zinc consumption (R) was found to increase with increasing the relative velocity according to equations: R=3.9×10⁻⁴ Re^0.0126; for Re<3,500, and R=7.36×10⁻⁶ Re^0.5; for Re>3,500, where Re is the Reynolds number. The degree of cathodic protection represented by the hull (cathode) potential at a given distance from the anode was found to decrease slightly with increasing the relative velocity.

The present results would make it possible for the designer of sacrificial cathodic protection systems to assess the amount of zinc required to protect the ship hull under certain operating conditions more accurately than the situation where the effect of the relative velocity was not considered.

Introduction Recently, a new type of corrosion inhibitor, namely drag‐reducing polymer, has been developed for combating diffusion‐controlled corrosion of metals subjected to turbulent flow. The mechanism of inhibition is based on the ability of some high‐molecular‐weight polymers to damp turbulent eddies at the corroding surface with a consequent increase in the diffusion layer thickness, across which transfer of dissolved oxygen (depolarizer) or corrosion products takes place. This gives rise to a considerable decrease in the rate of metallic corrosion. Along with corrosion inhibition, the damping of turbulent eddies leads also to a reduction in the friction between the turbulently flowing fluid and the metallic surface, with a consequent decrease in the power required to move the fluids. The majority of previous studies on the use of drag‐reducing polymers as corrosion inhibitors have been conducted using turbulent flow in pipelines.

Purpose – The aim of this research was to test whether the motivations of self-enhancement and self-verification act independently and simultaneously, specifically in the context of the impostor phenomenon.

Design/methodology/approach – Using both self-report measures and salivary cortisol levels, I conducted a 2×2 experiment (N=106) in which status (high or low) was crossed with competition outcome (win or lose). The “low-status winner” condition served as a simulation of the impostor phenomenon.

Findings – Winners reported greater positive affect and less negative affect, indicating self-enhancement, but salivary cortisol levels were higher in participants whose status was disconsonant with the competition outcome (high-status losers and low-status winners), reflecting self-verification.

Research limitations/implications – A potential limitation was the omission of nicotine use as a control variable.

Practical implications – Results illuminate the dual public and private nature of the impostor phenomenon, in which normative expressions of happiness overlie deeper feelings of anxiety. A better understanding would benefit educators, employers, counselors, and therapists who work with high-achieving women and minorities as well as the women and minorities they serve.

Social implications – Findings suggest that efforts should be made to bolster the confidence of promising young women and minorities, with the understanding that, despite high levels of achievement, self-confidence and a sense of deservedness may be lacking.

Originality/value – Methodological advancements included the first laboratory simulation of the impostor phenomenon and the use of both self-report and physiological measures of responses to status situations. This was the first study capable of observing the motivations to self-enhance and self-verify simultaneously and independently of one another.

The purpose of this paper is to develop the models of the dielectric permittivity dispersion of heterogeneous systems based on semiconductors to a level that would allow to apply effectively the method of broadband dielectric spectroscopy for the study of electronic processes in ceramic and composite materials.

The new approach for determining the complex dielectric permittivity of heterogeneous systems with semiconductor particles is used. It includes finding the analytical expression of the effective dielectric permittivity of the separate semiconductor particle of spherical shape. This approach takes into account the polarization of the free charge carriers in this particle, including capturing to localized electron states. This enabled the authors to use the known equations for complex dielectric permittivity of two-component matrix systems and statistical mixtures.

The presented dispersion equations establish the relationship between the parameters of the dielectric spectrum and electronic processes in the structures like semiconductor particles in a dielectric matrix in a wide frequency range. Conditions of manifestation and location of the different dispersion regions of the complex dielectric heterogeneous systems based on semiconductors in the frequency axis and their features are established. The most high-frequency dispersion region corresponds to the separation of free charge carriers at polarization. After this region in the direction of reducing of the frequency, the dispersion regions caused by recharge bulk and/or surface localized states follow. The most low-frequency dispersion region is caused by recharging electron traps in the boundary layer of the dielectric matrix.

Dielectric dispersion models are developed that are associated with: electronic processes of separation of free charge carriers in the semiconductor component, recapture of free charge carriers in the localized electronic states in bulk and on the surface of the semiconductor and also boundary layers of the dielectric at the polarization. The authors have analyzed to situations that correspond applicable and promising materials: varistor ceramics and composite structure with conductive and semiconductor fillers. The modelling results correspond to the existing level of understanding of the electron phenomena in matrix systems and statistical mixtures based on semiconductors. It allows to raise efficiency of research and control properties of heterogeneous materials by dielectric spectroscopy.

This study examined the role of artificial intelligence (AI) tools in facilitating the accessibility and usability of electronic resources (e-resources) in academic libraries.

This study employed a quantitative descriptive survey to collect data from library users. The population targeted was sampled using a purposive sampling technique. A total of 427 (58%) participated in this study.

Most respondents preferred electronic journals (e-journals) among the e-resources stored in academic libraries. Chatbots were identified as preferred AI tools for accessing and enhancing the usability of these resources. Strategies mentioned included the potential for integrating AI tools across various e-resources. However, among the challenges reported was the inability to integrate AI tools with the existing library management systems. Improving e-resource discovery and access can significantly enhance the effectiveness of AI tools in academic libraries.

Originality in the context of AI applications in academic libraries refers to the unique approaches, innovative tools and creative solutions that enhance the accessibility and usability of electronic resources. By focusing on unique solutions that enhance the accessibility and usability of e-resources, these libraries can better serve their diverse user populations and adapt to the evolving landscape of information needs.

Previous research indicates that vitamin D and omega-3 co-supplementation may benefit overall health, but current evidence regarding its effects on lipid profile remains unclear. The present systematic review and meta-analysis aimed to examine the effects of vitamin D and omega-3 co-supplementation on lipid profile (total cholesterol [TC], low-density lipoprotein [LDL], triglyceride [TG] and high-density lipoprotein [HDL]) in adults.

In this systematic review and meta-analysis, relevant studies were obtained by searching the PubMed, Scopus and Web of Science databases (from inception to January 2022). Weighted mean differences and 95% confidence intervals were estimated via a random-effects model. Heterogeneity, sensitivity analysis and publication bias were reported using standard methods.

Pooled analysis of six randomized controlled trials (RCTs) revealed that vitamin D and omega-3 co-supplementation yielded significant reductions in TG (p = 0.631). A pooled analysis of five trials indicated a significant association between omega-3 and vitamin D treatment and reductions in TC (p = 0.001) and LDL (p = 0.001). Although, pooled analyses of omega-3 and vitamin D did not significantly affect HDL.

The findings suggest that vitamin D and omega-3 co-supplementation lowers TG, TC and LDL in adults. Future, large-scale, RCTs on various populations are needed to elucidate further beneficial effects of vitamin D and omega-3 co-supplementation on lipid profile and establish guidelines for clinical practice.

The oil and gas construction projects are affected negatively by the drop in oil price in recent years. Thus, most engineering, procurement and construction (EPC) companies are opting to optimize the project mainly to mitigate the source of risks in construction to achieve the project expectation. Risk factors cause a threat to the project objectives regarding time, cost and quality. It is additionally a vital component in deviating from the client's expectation of productivity, safety and standards. This research aims to investigate the causes of risk in the oil and gas construction projects in Yemen.

A comprehensive literature review from various sources including books, conference proceedings, the Internet project management journals and oil and gas industry journals was conducted to achieve the objectives of this study. This initial work was predicated strictly on a literature review and the judgments of experts to develop the risk factor framework for the oil and gas construction projects in Yemen.

The authors found a few studies related to risk factors in oil and gas construction projects and shared a similar view about general construction projects. However, only a fraction of the factors accepted have included the variances of other studies on a regional basis or specific countries, such as the Yemen situation, due to the differences between the general construction industry and oil and gas industry. Moreover, the factors of these attributes were still accepted due to their applicability to the oil and gas industry, and no significant variances existed between countries. Research has indicated that 51 critical factors cause risks in the oil and gas construction projects in Yemen. Such risk factors can be divided into two major groups: (1) internal risk factors, including seven critical sources of risks, namely client, contractor, consultant, feasibility study and design, tendering and contract, resources and material supply and project management; and (2) external risk factors, including six sources of critical risk factors, namely national economic, political risk, local people, environment and safety, security risk and force-majeure-related risk factors. A risk factor framework was developed to identify the critical risk factors in the oil and gas construction projects in Yemen.

This research was limited to the oil and gas construction projects.

Practically, this study highlights the risk factors that cause a negative effect on the success of oil and gas construction projects in Yemen. The identification of these factors is the first step in the risk management process to develop strategic responses for risks and enhance the chances of project success.

The identification of risks factors that cause the failure of construction projects helps develop response strategies for these risks, thereby increasing the chances of project success reflected in the oil and gas sector, which is a main tributary of the national economy in developing countries.

This research is the pioneer for future investigations into this vital economic sector. Given the lack of resources and studies in the field of construction projects for the Yemeni oil and gas sector, the Yemeni government, oil companies and researchers in this field are expected to benefit from the results of this study. The critical risk factors specific to the oil and gas construction projects in Yemen should be further investigated with focus only on Yemen and its oil and gas industry players.

The purpose of the study reported in this paper is to synthesis curcumin, which was reported to possess broad pharmacological effects and excellent dyeing properties, via Claisen-Schmidt condensation reaction catalysed by an efficient and green solid base catalyst, KF/Al₂O₃.

A series of catalysts with different KF loadings and varying calcination temperatures had been prepared, characterised by Brunauer–Emmett–Taller surface area, temperature-programmed desorption with CO₂ using infrared spectroscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy, and tested in the Claisen–Schmidt condensation reaction. The effects of different reaction parameters such as temperature, the amount of catalyst, reactant ratio and time on the synthesis of curcumin were examined. The possibility of recycling the catalyst was also investigated in detail. Moreover, the reaction mechanism and the role of KF/Al₂O₃ in the synthetic process were discussed.

The study provides an efficient and green solid base catalyst, KF/Al₂O₃, and 64.3 per cent yield of curcumin was obtained under the optimum reaction conditions. Experimental results indicate that the third reused catalyst could retain part of the catalytic activity, and the regenerated one could be reused with reasonable catalytic activity. Besides, K₃AlF₆ was proposed as the active site of the catalyst for the reaction by the analysis of the characterization results of KF/Al₂O₃.

KF/Al₂O₃ was found to be an efficient catalyst for catalytic synthesis of curcumin and could be easily recycled several times. This information may be useful for further research and practical applications of curcumin.