Showing papers by "King Fahd University of Petroleum and Minerals published in 2018"

Outstanding Challenges in the Transferability of Ecological Models.

Abstract: Predictive models are central to many scientific disciplines and vital for informing management in a rapidly changing world However, limited understanding of the accuracy and precision of models transferred to novel conditions (their ‘transferability’) undermines confidence in their predictions Here, 50 experts identified priority knowledge gaps which, if filled, will most improve model transfers These are summarized into six technical and six fundamental challenges, which underlie the combined need to intensify research on the determinants of ecological predictability, including species traits and data quality, and develop best practices for transferring models Of high importance is the identification of a widely applicable set of transferability metrics, with appropriate tools to quantify the sources and impacts of prediction uncertainty under novel conditions

Frontiers, opportunities, and challenges in perovskite solar cells: A critical review

Abstract: The breakthrough discovery of organic-inorganic hybrid perovskite materials for converting solar energy into electrical energy has revolutionized the third generation photovoltaic devices. Within less than half a decade of rigorous research and development in perovskite solar cells, the efficiency is boosted upto 22%. Aforesaid high PCE is accredited to high optical absorption properties, balanced charge transport properties, and longer diffusion lengths of carriers. Two dominant perovskite solar cell architecture has evolved; n-i-p, and p-i-n with mesoporous or planar heterojunction. In planar heterojunction configuration, perovskite light harvester is layered between hole/electron transport layers and the electrodes. The electron and hole transporting films increase charge collection efficiency and reduce recombination at interfaces. In the following review, we present a critical survey of the recent progress in perovskite absorber and charge transport materials that account for the exceptionally higher PCE of perovskite devices. Furthermore, numerous fabrication techniques and device architectures are summarized.

Biosynthesis of Metal Nanoparticles via Microbial Enzymes: A Mechanistic Approach.

Abstract: During the last decade, metal nanoparticles (MtNPs) have gained immense popularity due to their characteristic physicochemical properties, as well as containing antimicrobial, anti-cancer, catalyzing, optical, electronic and magnetic properties. Primarily, these MtNPs have been synthesized through different physical and chemical methods. However, these conventional methods have various drawbacks, such as high energy consumption, high cost and the involvement of toxic chemical substances. Microbial flora has provided an alternative platform for the biological synthesis of MtNPs in an eco-friendly and cost effective way. In this article we have focused on various microorganisms used for the synthesis of different MtNPs. We also have elaborated on the intracellular and extracellular mechanisms of MtNP synthesis in microorganisms, and have highlighted their advantages along with their challenges. Moreover, due to several advantages over chemically synthesized nanoparticles, the microbial MtNPs, with their exclusive and dynamic characteristics, can be used in different sectors like the agriculture, medicine, cosmetics and biotechnology industries in the near future.

A Review of Carbon Nanomaterials' Synthesis via the Chemical Vapor Deposition (CVD) Method.

Abstract: Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbide-derived carbon (CDC), carbon nano-onion (CNO) and MXenes. Furthermore, current challenges in the synthesis and application of these nanomaterials are highlighted with suggested areas for future research.

Role of plant phytochemicals and microbial enzymes in biosynthesis of metallic nanoparticles.

Abstract: Metal-based nanoparticles have gained tremendous popularity because of their interesting physical, biological, optical, and magnetic properties. These nanoparticles can be synthesized using a variety of different physical, chemical, and biological techniques. The biological means are largely preferred as it provides an environmentally benign, green, and cost-effective route for the biosynthesis of nanoparticles. These bioresources can act as a scaffold, thereby playing the role of reducing as well as capping agents in the biosynthesis of nanoparticles. Medicinal plants tend to have a complex phytochemical constituent such as alcohols, phenols, terpenes, alkaloids, saponins, and proteins, while microbes have key enzymes which can act as reducing as well as stabilizing agent for NP synthesis. However, the mechanism of biosynthesis is still highly debatable. Herein, the present review is directed to give an updated comprehensive overview towards the mechanistic aspects in the biosynthesis of nanoparticles via plants and microbes. Various biosynthetic pathways of secondary metabolites in plants and key enzyme production in microbes have been discussed in detail, along with the underlying mechanisms for biogenic NP synthesis.

Optimal sizing of a wind/solar/battery hybrid grid-connected microgrid system

Abstract: Higher cost and stochastic nature of intermittent renewable energy (RE) resources complicate their planning, integration and operation of electric power system. Therefore, it is critical to determine the appropriate sizes of RE sources and associated energy storage for efficient, economic and reliable operation of electric power system. In this study, two constraint-based iterative search algorithms are proposed for optimal sizing of the wind turbine (WT), solar photovoltaic (PV) and the battery energy storage system (BESS) in the grid-connected configuration of a microgrid. The first algorithm, named as sources sizing algorithm, determines the optimal sizes of RE sources while the second algorithm, called as battery sizing algorithm, determines the optimal capacity of BESS. These algorithms are mainly based upon two key essentials, i.e. maximum reliability and minimum cost. The proposed methodology aims to avoid over- and under-sizing by searching every possible solution in the given search space. Moreover, it considers the forced outage rates of PV, WT and utilisation factor of BESS which makes it more realistic. Simulation results depict the effectiveness of the proposed approach.

Effect of electron donating functional groups on corrosion inhibition of mild steel in hydrochloric acid: Experimental and quantum chemical study

Abstract: The corrosion inhibition performance of three triazine derivatives namely 4-((2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)-N,N-dimethylaniline (HT-1), 3-(2-(4 methoxybenzylidene) hydrazineyl)-5,6-diphenyl-1,2,4-triazine (HT-2) and 2-(2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)phenol (HT-3)on mild steel corrosion in1MHCl has been studied using gravimetric method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), Density functional theory (DFT) and molecular dynamics simulation. The corrosion inhibition efficiencies at optimum concentration (80 mg L-1) are 98.6% (HT-1), 97.1%(HT-2) and 94.3% (HT-3) respectively at 308 K. The corrosion inhibition efficiency increases with increase in concentration and decreases with increase in temperature. The adsorption of HTs on the surface of mild steel obeyed Langmuir isotherm. Potentiodynamic polarization study confirmed that inhibitors are mixed type with cathodic predominance. SEM analysis confirmed that metal surface is smooth in presence of inhibitors. Quantum chemical calculation and Molecular dynamics simulation further support the experimental findings.

Nanomaterials-based electrochemical detection of heavy metals in water: Current status, challenges and future direction

Abstract: The existence of heavy metals in the natural waters poses serious threats to human health and the environment. Therefore, development of detection methods for monitoring of these heavy metals is crucial. The nanomaterial-based electrochemical sensors have been extensively employed for heavy metal ions detection. The fabricated electrodes offer several advantages and improved performance due to the design of electrode surface at the nanoscale that render increased catalytic activity and conductivity, active large surface area and fast electrode kinetics. Moreover, integration of electrochemical devices in automatic fluidic structures has also been used for a wide range of heavy metals monitoring. This review will provide a detailed account of recent progress in the development of nanomaterial-based electrochemical sensors for the detection of heavy metals in real water samples from 2013 onwards. The design of these sensors is based on the deployment of nanoparticles-modified electrodes, microelectrode and nanoelectrode arrays, and microfluidic electrochemical devices.

Nanomaterial-based optical chemical sensors for the detection of heavy metals in water: Recent advances and challenges

Abstract: The anthropogenic release of heavy metals into the natural water has become a global epidemic. Heavy metal contamination poses serious threats to human health and the environment. Therefore, the development of sensors for monitoring of these toxic metals in different matrices, especially in water, is very important. As a powerful analytical tool, nanomaterial-based chemical sensors have been extensively employed for the detection of heavy metals. These nanosensors offer several advantages including high sensitivity, selectivity, portability, on-site detection ability and improved performance of devices. Moreover, the deployment of molecular recognition probe on the nanostructures for the selective binding have enhanced the selectivity and detection ability. In this review, we critically engross on the recent progress in the design of nanomaterial-based sensors for the detection of heavy metals using various sensing strategies. The optical sensors focused and discussed in the review include fluorescent, surface enhanced Raman scattering and surface plasmon resonance sensors.

Production of Plant Secondary Metabolites: Examples, Tips and Suggestions for Biotechnologists.

Abstract: Plants are sessile organisms and, in order to defend themselves against exogenous (a)biotic constraints, they synthesize an array of secondary metabolites which have important physiological and ecological effects. Plant secondary metabolites can be classified into four major classes: terpenoids, phenolic compounds, alkaloids and sulphur-containing compounds. These phytochemicals can be antimicrobial, act as attractants/repellents, or as deterrents against herbivores. The synthesis of such a rich variety of phytochemicals is also observed in undifferentiated plant cells under laboratory conditions and can be further induced with elicitors or by feeding precursors. In this review, we discuss the recent literature on the production of representatives of three plant secondary metabolite classes: artemisinin (a sesquiterpene), lignans (phenolic compounds) and caffeine (an alkaloid). Their respective production in well-known plants, i.e., Artemisia, Coffea arabica L., as well as neglected species, like the fibre-producing plant Urtica dioica L., will be surveyed. The production of artemisinin and caffeine in heterologous hosts will also be discussed. Additionally, metabolic engineering strategies to increase the bioactivity and stability of plant secondary metabolites will be surveyed, by focusing on glycosyltransferases (GTs). We end our review by proposing strategies to enhance the production of plant secondary metabolites in cell cultures by inducing cell wall modifications with chemicals/drugs, or with altered concentrations of the micronutrient boron and the quasi-essential element silicon.

Effect of particle size on the viscosity of nanofluids: A review

Abstract: Nanofluids are potential new generation heat transfer fluids, which have been investigated meticulously, in recent years. Thermophysical properties of these fluids have significant influence on their heat transfer characteristics. Viscosity is one of the most important thermophysical properties that depends on various parameters. Size of the particles used in nanofluids is one of these effecting parameters. In this work, experimental studies considering the particle size effect on the viscosity of the nanofluid have been reviewed. Firstly, comparison of nanofluid and surfactant type, production and measurement methods were considered. Viscosity results of selected studies were evaluated in view of the parameters such as particle size, temperature and concentration. Furthermore, effective viscosity models of nanofluids, which include particle size as a parameter were discussed. The results indicate that there is a discrepancy about the effect of particle size on the viscosity of nanofluids. Moreover, it is observed from the evaluated data that the relative viscosity variation can be almost 40% either upwards or downwards by only altering the particle size.

The effect of environmental factors and dust accumulation on photovoltaic modules and dust-accumulation mitigation strategies

Abstract: The mitigation of environmental effects on clean-energy technology is an area of increasing interest. Photovoltaic (PV) modules have been widely used in small and large-scale applications for many years. However, they are not yet competitive with other electrical energy-generation technologies, especially in environments that suffer from dust, airborne particles, humidity and high ambient temperatures. This paper presents a review of the effect of climatic conditions on PV module performance, in particular, the effect of dust fouling. Research to date indicates that dust deposition has a considerable effect on PV module performance as it reduces the light transmissivity of the PV module surface cover. Studies on the ways in which dust is deposited on PV module surfaces are reviewed, as understanding this process is essential to develop effective mitigation approaches. Module performance is also adversely affected by high ambient temperature, humidity and lack of rainfall. The current review summarizes the past, current and promising future approaches towards mitigating environmental effects, in particular dust fouling. Electrostatic cleaning methods and micro/nanoscale surface functionalization methods both have the potential to counteract the negative effects of dust deposition, with the combination of the two methods showing special efficacy, particularly in arid regions.

A Review on Recent Advances for Electrochemical Reduction of Carbon Dioxide to Methanol Using Metal–Organic Framework (MOF) and Non-MOF Catalysts: Challenges and Future Prospects

Abstract: Transformation of carbon dioxide into various chemicals including methanol is a top priority field of study owing to the association of CO2 with global warming. There is a need for renewable and sustainable energy sources and replacement of fossil fuel with a fuel having comparable energy density. Electrochemical reduction is a unique approach to convert CO2 to methanol by employing alternative energy sources where electrocatalyst plays a crucial role. A lot of effort is made to understand and increase the efficiency of electrocatalysts. Unadulterated metals, metal oxide, composite materials, and metal–organic frameworks (MOFs) are employed for the electrochemical reduction of CO2 to methanol. However, MOFs engrossed the enormous consideration due to simplicity, higher surface area, and unique structural features. In recent years, MOFs and their derivatives find significant applications in the electrocatalysis of oxygen and hydrogen evolution, oxygen, hydrogen, and CO2 reduction. The primary emphasis of t...

New Metal–Organic Frameworks for Chemical Fixation of CO2

Abstract: A novel series of two zirconium- and one indium-based metal–organic frameworks (MOFs), namely, MOF-892, MOF-893, and MOF-894, constructed from the hexatopic linker, 1′,2′,3′,4′,5′,6′-hexakis(4-carboxyphenyl)benzene, were synthesized and fully characterized. MOF-892 and MOF-893 are two new exemplars of materials with topologies previously unseen in the important family of zirconium MOFs. MOF-892, MOF-893, and MOF-894 exhibit efficient heterogeneous catalytic activity for the cycloaddition of CO2, resulting in a cyclic organic carbonate formation with high conversion, selectivity, and yield under mild conditions (1 atm CO2, 80 °C, and solvent-free). Because of the structural features provided by their building units, MOF-892 and MOF-893 are replete with accessible Lewis and Bronsted acid sites located at the metal clusters and the non-coordinating carboxylic groups of the linkers, respectively, which is found to promote the catalytic CO2 cycloaddition reaction. As a proof-of-concept, MOF-892 exhibits high c...