The energy source shortage has become a severe issue, and solving the problem with renewable and sustainable energy is the primary trend. Among the new generation energy storage, lithium-sulfur (Li-S) battery stands out for its low cost, high theoretical capacity (1,675 mAh g-1), and environmentally friendly properties. Intensive researches have been focusing on this system and significant improvement has been achieved. However, several problems still need to be resolved for its practical application, especially for...

Large dense matrices are ubiquitous in scientific computing, arising from the discretization of integral operators associated with elliptic pdes, Schur complement methods, covariances in spatial statistics, kernel-based machine learning, and numerical optimization problems. Hierarchical matrices are an efficient way for storing the dense matrices of very large dimension that appear in these and related settings. They exploit the fact that the underlying matrices, while formally dense, are data sparse. They have a structure consisting of...

This dissertation aims at theoretically studying a block of layers that is common in al- most all deep learning models. The block of layers of interest is the composition of an affine layer followed by a nonlinear activation that is followed by another affine layer. We study this block from three perspectives. (i) An Optimization Perspective. Is it possible that the output of the forward pass through this block is an optimal solution to a...

Abstract: Even though improvements in the efficiency of organic solar cells encouraged the commercialization of this technology in the past two decades, the stability of organic solar cells is still an active area of research. The effect of photo-oxidative degradation on the performance of organic solar cell devices is significant. One way to lower the rate of photooxidation degradation is by preventing oxygen molecules from reaching the active layer of organic solar cells. This could...

Years of unregulated fishing activity have resulted in low abundances of elasmobranch species in the Saudi Arabian Red Sea. Coastal populations of sharks and rays in the region remain largely understudied and may be at risk from large-scale coastal development projects. Here we aim to address this pressing need for information by using fish market, unmanned aerial vehicle and baited remote underwater video surveys to quantify the abundance and diversity of sharks and rays in...

Gaseous pollution has become a global issue and its presence above certain limits is hazardous to human health and environment. Detection of such gases is an immediate need and researchers around the world are trying to solve this problem. Metal oxides are being used as sensing materials for a long time, but a high operating temperature limits applications in many areas. On the other hand, two-dimensional (2D) materials with high surface-to-volume ratio and chemical stability...

Slippery liquid-infused porous surfaces (SLIPS) – a new class of bio-inspired liquid-repellent surfaces – comprise arbitrarily porous architectures filled with oils that exhibit high interfacial tensions to probe liquids and present ultralow contact angle hysteresis (<〖10〗^°). However, before practical technologies based on SLIPS can be designed at large-scale, a number of fundamental questions remain to be answered. For instance, depending on the sign of the spreading coefficient of the Vapor(V)-lubricant oil(O)-liquid(L) system, defined as S_(OL(V))=γ_LV-γ_LO-γ_OV>0,...

Mesenchymal stem cells (MSCs) are the most widely used source for bone tissue engineering due to their capability of multipotent differentiation. The use of nanotechnology in biomedical applications and therapy has increased in recent years provides an elegant alternative in comparison to current tissue engineering methods. Magnetic nanowires have a high potential in the medical field, as they are biocompatible, are simple to fabricate, possess low cytotoxic effects and can be operated wirelessly via magnetic...

In this thesis, we consider maximized power allocation of non-orthogonal multiple ac- cess (NOMA) schemes since it outperforms than orthogonal multiple access (OMA) for the high altitude platform networks (HAPNETs) both in the back- haul and access links. Secondly, we propose a cluster formation (CF) algorithm and power-bandwidth resource allocation (PB-RA) for solving the resource management of HAPNETs. We adopt the particle swarm optimization (PSO) algorithm to explore the optimal de- ployment of high altitude...

Abstract: TEM is one of the most powerful technologies for material research. In-situ TEM is a TEM technique that allows us to study samples in real-time. Researchers can focus on one area and change the conditions under the electron beam to acquire much more data from the material than conventional TEM techniques. In this research, we use the in-situ TEM technique to observe the rechargeable aqueous zinc-ion batteries which have been considered as a promising...

Worldwide, coral reefs are recognized as highly valuable ecosystems offering numerous environmental and economic services. In Saudi Arabia, the primary ecosystem service derived from coral reefs is the support of reef-based fisheries, accounting for ~75% of total fisheries landing in the kingdom. Saudi Arabian reefs experienced high fishing pressure for decades due to the growing population and associated fishing pressure. Despite the importance of the provisioning service there are limited ecosystem services valuations for this...

Halide perovskites have some unique advantages as optoelectronic materials. Metal halide perovskites have been attracting enormous attention for applications in optoelectronic devices such as photodetectors, light-emitting devices and field-effect transistors. The remarkable semiconducting properties have been intensively investigated in recent years. However, the performance of optoelectronics devices based on the conventional perovskite is limited by the ion migration, the mobility of the carriers and the light absorption in the near infrared region and so on....

UHRF1 is a critical epigenetic regulator which serves as a molecular model for understanding the crosstalk between histone modification and DNA methylation. It is integrated in the process of DNA maintenance methylation through its histone ubiquitylation activity, ultimately functioning as a recruiter of DNA methyltransferase 1 (DNMT1). As the faithful propagation of DNA methylation patterns during cell division is a common molecular phenomenon among vertebrates, understanding the underlying conserved mechanism of UHRF1 for executing such...

Transition metals are known to be the essential part in most of the catalysts, the heterogeneous and the homogenous catalysts; however, the ligands that attached to the metal centers can also alter the reactivity of the catalyst, and that is widely observed in nature. In our project, we are interested in the metal-ligand cooperation of a special type of ligand called the pincer ligand. Our focus is mainly on the tridentate Pincer Ligands with a...

The high specific energy consumption from all existing seawater desalination methods has heightened the motivation for having more efficient and greener desalination processes to meet the future goals of sustainable seawater desalination. One of the promising thermally-driven desalination methods is the direct-contact spray evaporation and condensation (DCSEC) where the excess enthalpy between feed and equilibrium states of evaporator chambers is exploited with reasonably high flashing efficiency. Further improvements in energy efficacy of DCSEC are boosted...

Soil data accumulated during the last century and more recent developments in sensors and information technology prompt the development of new geotechnical solutions for soil assessment. We have advanced three complementary tools: Lab-on-a-Bench, the soil properties database with corresponding IT Tool and the in-situ characterization Multiphysics Probe. Lab-on-a-Bench technology combines cutting-edge sensors and sensing concepts within compact devices and effective laboratory protocols to allow multi physics soil characterization: specific surface measurements for fine-grained soils and...

Abstract: Soot from combustion emissions has a negative impact on human health and the environment. Understanding and controlling soot formation is desirable to reduce this negative impact, especially as energy demands continue to increase. In this work, a range of fundamental combustion experiments are performed to better understand the soot formation process, and to develop diagnostics for measuring soot properties. First, studies on the effects of doping the flame with different polycyclic aromatic hydrocarbons (PAHs)...

Alternating current electrohydrodynamics (ac-EHD) has been reported as a promising technique for enhancing sensor performance by the intimate mixing of the analyte solution at the electrode surface. The lateral fluid motion created by the ac-EHD phenomenon can be tuned by changing the frequency, voltage, and electrode geometry. To date, various studies have been conducted on the use of 2D electrodes based ac- EHD devices for sensor applications. However, the use of 3D electrodes may provide...

Many key problems in machine learning and data science are routinely modeled as optimization problems and solved via optimization algorithms. With the increase of the volume of data and the size and complexity of the statistical models used to formulate these often ill-conditioned optimization tasks, there is a need for new efficient algorithms able to cope with these challenges. In this thesis, we deal with each of these sources of difficulty in a different way....

Abstract: The aim of this research is to fabricate thin-film composite (TFC) membranes using a synthetic derivative of plant-based phenols, as a non-toxic building block for interfacial polymerization. Classical interfacially polymerized composite membranes are heavily integrated in reverse osmosis and nanofiltration applications for water and wastewater treatment and most recently for chemical and pharmaceutical industries. Implementing sustainable practices in membrane fabrication by exploiting greener alternatives to conventional chemicals can directly reduce hazardous waste and ultimately...

Arid and semi-arid regions, mostly found in developing countries with exponentially increasing populations, are in chronic lack of water thereby severely limiting agricultural production. Irrigation with saline water, which is available in large quantities, could be an obvious solution, but current crops are all salt sensitive. Although major efforts are underway to breed salt tolerant crops, no breakthrough results have yet been obtained. One alternative could rely on plant-interacting microbiota communities. Indeed, rhizophere and endosphere...

Gallium nitride (GaN) is a semiconductor material highly regarded for visible light generation since it provides the most efficient platform for compact violet, blue, and green light emitters, and in turn, high-quality and ubiquitous white lighting. Despite this fact, the potential of the GaN platform has not been fully exploited. This potential must enable the precise control in the various properties of light, realizing functions beyond the conventional. Simultaneously, the field of the telecommunications is...

3D printing, also known as ”additive manufacturing”, indicates a set of fabrication techniques that build objects by adding material, typically layer by layer. The main advantages of 3D printing are unlimited shapes and geometry, fast prototyping, and cost-effective small scale production. Two-photon lithography (TPL) is a laserbased 3D printing technique with submicron resolution, that can be used to create miniaturized structures. One of the most compelling applications of TPL is the 3D printing of miniaturized...

Human society can be thought of as a heat engine that is powered by fossil fuel and sunlight. The free energy that fossil fuels provide has enabled the development of our modern global human civilization and has artificially raised the human carrying capacity of the planet. Here, I discuss the roots of human population theory in the context of environmental limits, and argue that examining this issue is an essential matter of public health. The...

A central topic in the research of nanophotonics is the geometrical optimization of the nanostructures since the geometries are deeply related to the Mie resonances and the localized surface plasmon resonances in dielectric and metallic nanomaterials. When many nanostructures are assembled to form a metamaterial, the tuning of the geometrical parameters can bring even more profound effects, such as bound states in the continuum (BIC) with infinite quality factors (Q factors). Moreover, with the development...