bluuebunny/crossref_metadata_2025 huggingface dataset:
Longterm Seasonal Variability of Photovoltaic Surface Soiling and Subsequent Power Loss in Doha Qatar
Authors: Javed Wasim , Guo Bing , Figgis Benjamin , Wubulikasimu Yiming
Published: June 2019

Dust accumulation or soiling on solar panels' and collectors' surfaces has become a well-known problem, which severely reduces the performance of solar energy conversion systems. The soiling of the solar surfaces is a complex phenomenon influenced by various site-specific environmental and weather factors, and therefore should demonstrate seasonal and weather-dependent trends. Such information of natural PV soiling would be useful not only for modeling the economic impact of surface soiling but also for properly scheduling of cleaning, which is of interest to project developers and operators. The purpose of the study is to investigate the long-term seasonal patterns of airborne dust accumulation on PV modules and soiling-induced PV performance degradation in the desert environment of Qatar. PV performance, ambient dust concentration and meteorological data were collected over the study period of 2014-2017. Results revealed that PV performance due to soiling in terms of daily change in the cleanness index (ΔCI) varied with season, which was attributed to substantial variations in environmental conditions (i.e., rainfall, wind speed, humidity, temperature, airborne dust concentration). Averaged over the four years, the daily ΔCI was − 0.43 ± 1.0% per day for modules cleaned every sixth month, and − 0.46 ± 1.05% per day for modules cleaned every second month or about 14% per month. The annual pattern shows significant seasonal variation of daily ΔCI and cumulative CI during the study period. Daily ΔCI was found to be the most severe during November ( − 0.75%) and least during June ( − 0.19%). The months correspond to the rainy season (i.e., February to April) have moderate values of ΔCI ( − 0.34%). It was observed that average daily ΔCI by month was decreased with increasing PM10 concentration and humidity and increased with that of temperature and wind speed. The intense dust storm and rainy events taking place on specific days of the month are predominantly responsible for the large month-to-month variations of PV soiling. A yearly soiling trend was also determined that could help to reduce uncertainty in energy yield prediction. Monthly dust deposition on PV modules was also determined gravimetrically, which also showed month-to-month variation following the same trend of monthly PV performance loss. In addition to the environmental factors affecting dust accumulation on PV modules, particle size distribution and chemical properties of the monthly-collected dust were investigated and compared as well.
Low cost anode electrocatalyst for Direct Methanol Fuel Cell applications
Authors: Zaidi Syed Javaid , Alsaydeh Sajeda Adnan Mutlaq , Yousaf Ammar Bin
Published: June 2019

Direct methanol fuel cell has attracted worldwide attention as a promising alternative clean energy source due to growing environmental problems. A number of scientific groups are working to develop the fuel cells and make it a viable clean energy option. For fuel cells to be a feasible and economic viable innovation in the materials development, such as new electrocatalyst and polymer electrolyte membranes are required. Significant advancements in materials developments are required for fuel cells to be feasible for a wide range of portable, automotive and stationary applications. For DMFC, there are some challenges that need to be addressed before this technology become competitive, for example- slow kinetics of methanol oxidation, high methanol permeation resulting drop in fuel cell performance and the high cost of the catalyst. In the present work we focus on the electrocatalyst materials development for methanol electro-oxidation on the anode surface of DMFC. Platinum (Pt) and/or copper (Cu) based multi composition low cost electro-catalyst have been synthesized and characterized by impregnating onto the carbon nano-tubes (CNT) composites. These nanocomposite electrocatalyst materials have been characterized for their morphology by scanning electron microscopy (SEM), structure by X-Ray Diffraction (XRD), element mapping and other chemical and thermal properties by Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray Photoelectron Spectroscopy (XPS). The results of the characterization confirmed successful formation of the desired electrocatalyst material. The electrochemical activity of these electro-catalysts for methanol electro-oxidation have been studied by cyclic voltametry (CV) and chronoamperometery (CA) at various concentrations of methanol and current density. The characterization and electrochemical activity tests showed good performance for the electro-oxidation of methanol for DMFCs. The present study opened up new avenues for developing lower cost Pt-based catalysts with better performance. These nanomaterials have potential to be used as electrocatalyst for DMFC applications. Keywords: Electrocatalyst, nanocomposite;direct methanol fuel cells, electro-oxidation. Acknowledgements: This publication was supported by Qatar university Internal Grant No. QUUG-CAM-15\16-2. The findings achieved herein are solely the responsibility of the author[s].
Conjugated polymer's side chains postprocessing for improved molecular packing and mobility of organic thinfilm transistors OTFTs
Authors: Barlog Maciej
Published: June 2019

Soluble conjugated polymers have nowadays attracted broad academic and industrial spotlight as innovative materials of easy tuneable optical and electronic properties.1 These properties translate into various optoelectronic applications such as organic solar cells, light-emitting diodes (LEDs), and thin film transistors. The pivotal parameters that define characteristics of conjugated polymer based devices are of chemical (structure, solubility, mass) and mechanical (macroscopic) nature.2 Although the physical properties CPs is determined by designed chemical structure, critical alterations result from variations of the nanostructure of the polymer in its solid state.3 Therefore the complete optoelectronic potential of CP based device can be fully assessed only with the optimal conjugated chains alignment. We envisioned thermal and UV induced post processing of conjugated polymers predesigned to dramatically change their properties in given conditions by removal of nonconductive side chains and reducing interlayer distance.
Adaptive model of thermal comfort for office buildings in GCC
Authors: Indraganti Roberto , Boussaa Djamel
Published: June 2019

The Gulf Cooperation Council (GCC) nations top the world in CO2 emissions/ capita. However, plummeting oil prices and increasing energy demands necessitate rethinking on thermal comfort delivery. This region has warm desert climate throughout. In GCC states, the adaptive comfort standard or the precursor field studies to develop one are non-existent. We carried out thermal comfort field studies in Qatar for thirteen months. In ten typical air-conditioned office buildings, 1175 voluntary subjects completed 3742 questionnaires, while their thermal environments were simultaneously measured. This paper proposes the adaptive model of thermal comfort for GCC. Adopting variable indoor comfort standards that track the outdoor conditions may be effectual in meeting the sustainability goals of the GCC and Qatar Vision 2030.
Designing Photo Absorbing Materials by Cation Substitutions for Photovoltaics
Authors: Belayneh Merid Legesse
Published: June 2019

Designing Photo Absorbing Materials by Cation Substitutions for Photovoltaics Merid Legesse1, Heesoo Park1, Fedwa El Mellouhi1, Sergey N Rashkeev1, Sabre Kais1, 2, 3, Fahhad H Alharbi1, 3 1Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, Qatar. 2Department of Chemistry and Physics, Purdue University, West Lafayette, Indiana 46323, USA. 3College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar. Email: mbelayneh@hbku.edu.qa. Recently, significant research efforts have focused on some emerging solar cell technologies such as dye-sensitized solar cells, perovskite photovoltaics, etc. However, these technologies face many challenges. In this talk, we will present a new family of light absorbing materials so-called pyroxene silicates. These materials are abundantly present in the earth crust however, bandgaps of naturally formed pyroxene silicates such as NaAlSi2O6 are quite high (∼5 eV). Therefore, it is important to find a way to reduce bandgaps below 3 eV to make them usable for optoelectronic applications [1, 2, 3]. Using first-principles calculations we investigated the possibility of band structure engineering of pyroxene silicates with chemical formula A+1B+3Si2O6 by proper cation substitution (A+ =  Na, NH4+, PH4+, SH3+, CH3NH3+, CH3PH3+, CH3SH2+ and B3+ =  Al3+ Ga3+, In3+, Tl3+). We found that appropriate substitutions of both A+ and B3+ cations can reduce the bandgaps of these materials to as low as 1.31 eV. In this talk, we will also discuss in details how the bandgap in this class of materials is affected and thermodynamic stabilities. We would like to thank Qatar National Research Foundation (QNRF) for the support (Grant No. NPRP 7-317-1-055. References (1) A.A.B. Baloch, S.P. Aly, M.I. Hossain, F. El-Mellouhi, N. Tabet, and F.H. Alharbi, Sci. Rep. 7, 11984 (2017). (2) F. El Mellouhi, A. Akande, C. Motta, S.N. Rashkeev, G. Berdiyorov, M.E.A. Madjet, A. Marzouk, E.T. Bentria, S. Sanvito, S. Kais, and F.H. Alharbi, ChemSusChem 10 1931 (2017). (3) F.H. Alharbi, S.N. Rashkeev, F. El-Mellouhi, H. P. Lüthi, N. Tabet, S. Kais, npj Comput. Mater 1, 15003 (2015).
Core Scale Analysis on Asphaltene Flocculation Inhibition and Deposits Removal by Ultrasonication
Authors: Amani Mahmood
Published: June 2019

Asphaltene buildup in the near wellbore region is an increasingly problematic phenomenon, especially in mature fields. Research on ultrasonic treatment to address this issue has increased in recent years, with a field trial on mature fields exhibiting favorable characteristics. Investigation of petrophysical characteristics, precipitation of asphaltenes in rock samples, employment of ultrasonication to remove/inhibit deposits, investigation of optimum sonication time, and the resultant increase of permeability to brine and crude oil are discussed and illustrated. Prevention and or removal of asphaltene deposits inside the wellbore as well as the nearby wellbore region can significantly improve in the recovery of the petroleum reservoirs.
A Pilot Study on Evaluating the Microbial Quality of Produce Sold at the Wholesale Produce Market in Doha Qatar
Authors: El-Nemr Israa , Mushtaha Mohanad , Goktepe Ipek
Published: June 2019

Environmental and sanitary conditions play a major role on the quality of fresh produce. The Wholesale Produce Market (WPM) in Doha is an open-air market located in close proximity to the livestock market and slaughterhouse. Currently, there is no data available on establishing the link between the microbial quality of produce sold at this market and environmental factors affecting the quality of produce. Therefore, this pilot study was carried out to evaluate the effect of environmental conditions (e.g.; seasonal temperature, humidity, hygiene conditions of the market) on the microbial quality of produce sold at the WPM. Triplicate samples of different produce samples (e.g.; tomato, lettuce, parsley, cucumber, and green onion) were collected monthly starting from July 2016 to June 2017. Selective media were used to determine the target microorganisms (e.g.; total aerobic bacteria-PCA, total E.coli - MCA, total Listeria – LSA, total coliform - EMB, total Staphylococcus - BPA, total Salmonella - XLT4, and total fungal growth – PDA). The colonies identified as presumptive target organisms were isolated and identified using molecular techniques. The results indicated that produce samples (especially parsley, green onion, and lettuce) tested in this study were highly contaminated with various microorganisms based on the PCA, MCA, and EMB counts. The microbial analysis of produce samples revealed that the most dominant strains in summer months (47°C daytime and 25°C nighttime) were Bacillus, Enterococcus, and Klebsiella. While, Pseudomonas and Enterobacter were the most abundant species during the winter months (24°C daytime, 12°C nighttime). In addition, Penicillium, Aspergillus, and Fusarium were the most commonly isolated fungal species during the months of November-January. It is clear that environmental conditions, such as temperature and humidity are the major factors affecting the growth of different microorganisms in fresh produce. Although no pathogenic target bacteria were detected in the produce samples at WPM, the relatively high PCA and EMB counts demonstrate the need to improve the sanitary conditions at this major produce market in Qatar.
Corrosion behavior of high strength low alloy HSLA steel in 35 wt% NaCl solution containing diethylenetriamine DETA as corrosion inhibitor
Authors: Shakoor Abdul , Shahzad Khuram , Sliem Mostafa H. R , Ubaid Fareeha , Akbar Himyan M , Abdullah Aboubakr M , Kahraman Ramazan , Montemor Fatima M , Manzoor Umair
Published: June 2019

High strength low alloy (HSLA) steels demonstrate improved mechanical and anticorrosion properties when compared to plain carbon steels. HSLA steels have succeeded to find their major applications in industries such as defense (gun barrel, turret), food, component manufacturing, wind tunnels, power generation, and water jet cutting, etc. There are significant economic benefits to develop novel materials to mitigate the harmful effects of corrosion. At the same time, the corrosion challenges have also been addressed using various kinds of inhibitors. The corrosion inhibitors are commonly added to the corrosive medium in order to reduce their aggressive attack on the materials to improve their inhibition performance. The smart corrosion protection leads to secure our natural resources, time, efforts, energy and will also ensure a safe operation. The aim of this research work is to study the corrosion behavior of high strength low alloy steel (APIX120) in 3.5 wt.% NaCl solution containing different concentrations of diethylenetriamine (DETA). The electrochemical behavior of HSLA steel was investigated at room temperature using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss techniques. In addition, the adsorption isotherm, activation energy and other thermodynamic parameters were calculated from the electrochemical results. The corrosion products formed on the surface of the steel were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, surface topography and surface roughness of un-corroded and rusted samples were studied by atomic force microscopy (AFM) to elucidate the effect of the aggressive media on the corrosion performance of HSLA steel. Our study discloses that the inhibition efficiency of HSLA steel increases with increasing concentration of DETA in 3.5% NaCl solution.
Highly ordered mesoporous silica and halloysite nanotubes loaded with diethylenetriamine DETA for smart anti corrosion coatings
Authors: Shakoor Abdul , Ubaid Fareeha , Shahzad Khurram , Kahraman Ramazan , Montemor Fatima , Manzoor Umair
Published: June 2019

The development of nanoscience and technology has devoted significant attention to conducting studies on hollow particles. Among the available materials, mesoporous silica nanoparticles have recently gained attention as potential nanocontainers due to their high stability, large surface area, controllable pore diameter and easy surface functionalization as they can store and release organic or inorganic molecules of different sizes and functionalities. The aim of this work is to study the use of mesoporous silica as a potential reservoir for corrosion inhibitor for active corrosion protection of carbon steel and using epoxy encapsulated halloysite nanotubes for the self healing process of the epoxy based coatings. The synthesized mesoporous silica particles were characterized by using XRD, FTIR and SEM. Mesoporous silica particles loaded with diethylenetriamine (DETA) were embedded into the epoxy polymer along with the halloysite nanotubes (HNTs) encapsulated with epoxy monomer and amine immobilized in mesoporous silica with a weight ratio of 5 wt% of mesoporous silica. Kinetics of release of corrosion inhibitor was evaluated by electrochemical impedance (EIS) measurements in 3.5 wt% NaCl solution. The EIS analysis confirms that the release of inhibitor during the corrosion process has significantly improved the anticorrosion properties when compared to the epoxy coated sample without any corrosion inhibitor. The self healing phenomenon in the scratched epoxy coated sample was monitored by SEM during different time intervals. The SEM results showed that that the epoxy pre-polymer was slowly released into the crack.Upon release, the epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch over the sample surface. This study suggests that these novel coatings may have some potential applications in the oil and gas industry.
Utilization of Iron Magnetic Nanoparticles for the extraction of oil from aqueous environments
Authors: Matta Saly , Kumar Manyam Praveen , Adia Neil , Madrahimov Sherzod , Bergbreiter David
Published: June 2019

The goal of this research work is to help and to contribute toward the minimization and the control of manmade water pollution on land and in marine environment. Since oil spill is a major environmental polluter and causes server damage to natural habitats, the oil separation from aqueous phase using polyolefin-bound magnetic nanoparticles with superhydrophobic or water repellent properties has become a promising area of research that is worth exploring. Perfectly designed, functionalized polyisobutylene (PIB) bound iron magnetic nanoparticle could be utilized for facile separation of complex pollutants (crude oil), diesel, gasoline and organic solvents (petroleum ether, benzene, chloroform) from aqueous polluted environment conditions. 80–90% of recovery of pollutants by external magnetic field was easily reached and resuse of polyisobutylene-catechol bound to magnetic nanoparticle was investigated in detail. Polyisobutylene-catechol grafting on iron magnetic nanoparticle obtained 42–52%. Stability of the terminally functionalized polyisobutylene-catechol bound to iron oxide was confirmed by UV-Visible spectroscopy studies. Moreover, these experiments suggest that this work might provide promising candidate for environmental remediation including oil spill. This research work is an eco-friendly process and high oil absorption materials and can have wide applications in heterogenous and homogenous catalysis.
A survey on selfreported handling practices and food safety knowledge of workers at the major produce market in Qatar
Authors: El-Nemr Israa , Mushtaha Mohanad , Asim Hammad , Goktepe Ipek
Published: June 2019

Food handling practices (FHP) is one of the most important stage where microbes can be introduced into produce through the infected food handlers or by cross-contamination. The fresh produce market in Doha, Qatar is the major market from which most of the food businesses, restaurants, super markets, and consumers obtain their fresh produce. Produce is handled by workers with no or minimum knowledge on safe produce handling practices. This study was carried out to assess the food safety knowledge and self-reported handling practices applied by produce handlers working at this major produce market in Qatar. About 120 produce handlers were surveyed using a systematic questionnaire (No. QU-IRB 509-E/15) to determine their food safety knowledge and attitudes during handling of fresh produce in January 2016. In addition, hand-swab samples and work uniform photos were collected. A standard microbial count were applied on the collected swabs to determine the hands' hygiene levels of the workers. The identification of microorganisms isolated from their hand swabs was carried out using MALDI-TOFF. The survey results revealed that the hygiene practices and food safety knowledge among produce handlers working at this produce market are insufficient. It was determined that none of the handlers received any food safety training on safe produce handling practices before joining the work at the market. Most of the workers' age was below 50 yrs (82.5%), about 37% of them was between 31 and 40 years old. Regarding educational level; 57.5% of them had middle school degree or below. More than 60 % of them claimed to wash their hands 4–5 times per duty time. The microbial hand-swabbing analyses demonstrated the presence of Enterococcus faecium, Klebsiella pneumoniae, Staphylococcus spp., and Bacillus circulans. Overall, these results are significant because they highlight the need to promote additional efforts that might assist in developing necessary intervention strategies to improve the conditions at this major market and prevent future foodborne illness outbreaks linked to produce sold in Qatar.
Plasmonically Enhanced Schottky Solar Cell
Authors: Farhat MOHAMED , Kais Sabre , Alharbi Fahhad
Published: June 2019

Plasmonics is an emerging broad area of research, which studies the exceptional optical properties of metallic 2D and 3D nano-structures, i.e. confinement of electromagnetic waves (surface plasmon polaritons) [1]. During the past years, there has been a huge interest in employing plasmonic structures for sunlight harvesting [2], i.e. for example in thermal photovoltaics, thin-film solar cells, or solar thermoelectrics, etc. All these applications exploit the exceptional capabilities of plasmonic structures to concentrate electromagnetic energy and generate “hot” electrons. In this proposal [3], we aim to use plasmonic light confinement to build Schottky solar cells. The photovoltaic effect in these cells is induced by the metal (insulator) semiconductor interface (see figure below). And the presence of the plasmonic metal will increase the generated current in the active silicon layer and thus increase the overall efficiency of the cell.We wish to stress here that previous works using the plasmonic effect in solar cells, considered mainly the p-n junction [4], except the one using graphene with another semiconductor but not considering plasmonic effects [5]. In addition, we should mention, that the mechanism of the cell proposed here is intrinsically different from hot-electrons based plasmonic solar cells [6]. The novelty of this work is to use metallic strips for two functions simultaneously, i.e. as contact for electrons and as junction (Schottky barrier between metal and semiconductor). This permits a good efficiency with very simple structure (no need for having expensive semiconductor nor both doping, i.e. p and n for Silicon).We will discuss limitations and potentials of this kind of solar cells, in particular ease of fabrication.
Passive House Design Alternatives for Labor Camps in Modern AgroIndustrial Communities in Qatar
Authors: Hassabou Abdelhakim
Published: June 2019

The consumption of electricity in residential buildings exceeds 20% in Qatar and can go up to 50% in other hot countries like Kuwait. The air-conditioning systems in hot countries like Qatar consumes around 60–80% of the total energy demand in buildings. This triggers researchers and industry experts in the built environment to explore new avenues towards reducing the cooling load on a building and study influential factors to enhance energy efficiency in buildings in such extreme climatic conditions. The carbon foot print of buildings can be reduced by reducing the cooling load through passive building design, using high efficiency equipment and incorporating renewable energy technologies such as solar systems, air source heat pumps, wind generators and ground source heat pumps are few to name that are widely used among many other available renewable technologies. The focus of this research work is on the Passivehouse building design incorporating solar hybrid Photovoltaic Thermal collectors (PV/T) as a source of renewable electricity and solar hot water for domestic use. Two different designs of a residential building for Modern Agro-Industrial Communities in Qatar were considered i.e. Pyramidal Shaped Building and Square Shaped Building. 3D energy models were created for both type of buildings using the IES software (Integrated Environmental Solutions) in virtual environment and thermal analysis was carried out. For the same building type, orientation and structure, two different criteria were applied to the model i.e. Passivehouse design vs. Conventional design. Pyramid shaped buildings are more stable but tend to cost more to construct when compared to traditional buildings. The sloping external walls tend to gain more solar energy and daylight through windows installed on the external walls. This provides an opportunity for solar panels installation on the external walls. The solar gain through external windows can be reduced to a minimum by effective solar shading and the daylight harvesting system can further reduce the artificial lighting gain inside the building. The results show that the passive house design of a building can save more than 70% of the cooling plant load, the as installed plant size and associated infrastructure. This will also considerably reduce the annual operational and maintenance cost of the building with just an extra 15% in construction cost. The cost analysis of passive house in comparison with a conventional house was carried out by QGBC (Qatar Green Building Council). In a nutshell this research work demonstrates how buildings' cooling load and carbon foot print can be reduced by effective solar shading, lower infiltration rates (air tight building design), highly insulated building fabric, natural ventilation, daylight harvesting system (that can help reduce artificial lighting gain inside the building) and heat recovery system.
Compartmentalization and production allocation study of a carbonate field using molecular fingerprinting
Authors: Haeseler Frank , Couteyen-Carpaye Damien , Mahdaoui Fatima
Published: June 2019

In multi layered reservoirs the fluid composition may differ from one layer to another. The knowledge of the lateral and vertical fluid heterogeneities may help to better understand the fluid distribution in the field and consequently contribute to enlighten production. Several mechanisms can affect the fluid composition, like origin, maturity, alteration or physical conditions. The objective of this study is to present a methodology aiming at characterizing and quantifying the compositional differences between fluids from different layers in an oil reservoir. It allows mapping the vertical and lateral heterogeneities in fluid composition. In order to measure the hydrocarbon composition, samples are analyzed by HRGC (High Resolution Gas Chromatography). In a first step this method aims at finding the peak ratios discriminating the oils from different reservoirs. Data are processed for peak recognition and statistical comparison is performed to compare samples. This statistical interpretation allows identifying similarities and differences between chromatograms e.g. oils. The results allowed identification of two end members. All the other samples of the field could be described as a mixture of these two fluids. Different cross-sections have been analyzed aiming at better understanding the field by linking geochemical data with geological features. By coupling the result with geological (lithology, cross-sections, logs…) and reservoir data (porosity, permeability, saturation…), different explanations could be proposed: Possibility of having different end members originating from a same fluid.Water washing as a possible process affecting fluids from different layers in similar and continuous way.“Structural heights” susceptible to reduce the water washing effect for some wells.The dip of the layers might increase water washing effect on fluids. This study showed the possibility to allocate the production in a carbonate field and allowed a better understanding of the fluids distribution. The molecular fingerprinting made it possible to understand the origin of fluids in comingled wells and particularly to identify the most producing part of the well in horizontal drains.
Application of Value Engineering approach for Improving the Quality and Productivity of Ready Mixed Concrete Used in Construction and Hydraulic Projects
Authors: Ahmed Adel Mohamed
Published: June 2019

The paper studies the effectiveness of applying value engineering to concrete mixtures. It was conducted in the State of Qatar on a number of strategic construction projects for the 2022 World Cup projects, in order to generally improve the quality and productivity of ready-mixed concrete used in construction and hydraulic projects. The application of value engineering to such concrete mixtures resulted in the following: Improving the quality of concrete mixtures and increasing the durability of buildings; Optimizing the use of resources, and enhancing sustainability; Reducing the use of cement, thus reducing CO2 emissions which ensure the protection of environment and public health; And Increasing the market share and competitiveness of concrete producers The research shows that applying of value engineering to concrete is an effective way to save around 5% of the total costs of concrete mixtures and, in turn, reducing the costs of construction projects.
Heterojunction Solar Cells Exceeding 20% Efficiency Using Gettered Monolike Silicon Wafers
Authors: Kivambe Maulid M , Aïssa Brahim , Abdallah Amir A , Belaidi Abdelhak , Haschke Jan , Boccard Mathieu , Cattin Jean , Horzel Jörg , Despeisse Matthieu , Ballif Christophe , Tabet Nouar
Published: June 2019

Silicon heterojunction (SHJ) solar modules are an attractive and suitable option for application in high temperature environment such as in the state of Qatar. This is mainly related to their high open-circuit voltage (Voc) [1], which is essential for achieving better performance at high temperatures. High efficiency SHJ solar cells are usually made from high-quality n-type monocrystalline silicon wafers, which increases the cost of the device. If lower-cost materials such as high performance multicrystalline and mono-like silicon wafers could be used, significant reduction in the cost of PV electricity can be achieved. In this work, electrical properties of industrial-scale n-type and p-type mono-like silicon wafers have been investigated for use in high efficiency SHJ solar cells. The wafer's electrical resistivity were measured by four-point probe as 1–3 Ω-cm for n-type and ∼1 Ω-cm for p-type wafers. Since minority carrier lifetimes in as-grown (un-gettered) cast silicon, including mono-like silicon is usually low (i.e. inadequate for application in high efficiency solar cells), phosphorus diffusion gettering in a POCl3 furnace and/or bulk passivation by SiNx:H were used for enhancement of electrical properties. SHJ solar cells were then fabricated using the gettered wafers and as-grown sister wafers to assess the effectiveness of the gettering treatments. Figure 1. Injection dependent minority carrier lifetime for as-grown wafers and for gettered sister-wafers, after passivation with i/n and i/p amorphous silicon layers Figures. 1 shows minority carrier lifetimes measured by Quasi Stead-State Photoconductivity (QSSPC), on wafers as-grown, gettered and gettered with SiNx:H bulk passivation. As-grown lifetimes are low, being < 170 μs for p-type wafers and < 370 μs for n-type wafers, at 1 × 1015 cm-3 injection level. After passivation, significant improvement (up to 520 μs for p-type and 1900 μs for n-type) was achieved at 1 × 1015 cm-3 injection level. Despite the significant enhancement in overall lifetime, lifetimes at low-injection level is still limited, particularly for the p-type silicon. Nevertheless, very high carrier lifetime (up to 2400 μs) was recorded at 1 × 1015 cm-3 injection level (Figure 1(a)), and a SHJ cell with VOC of 720 mV and a photo-conversion efficiency of 20.3 % were successfully achieved, by gettering and bulk passivation. In conclusion, we demonstrated that electrical properties of industrial-scale mono-like silicon wafers can be efficiently optimized by gettering and bulk passivation treatments for application in high efficiency solar cells. A silicon heterojunction solar cell with efficiency exceeding 20% was produced. References [1] S. De Wolf, A. Descoeudres, Z. C. Holman, and C. Ballif, «High-efficiency silicon heterojunction solar cells: A review,» Green, vol. 2, pp. 7–24, 2012.
Synthesis and Properties of Novel NiBAlN Nanocomposite Coatings
Authors: Bahgat Ahmed , Mahmoud Abdelrahman Adel , Ahmed Said Elmi , Ali Kamran , Shakoor R.A. , Kahraman Ramazan , Montemor F.M.
Published: June 2019

Degradation of materails due to corrosion has now emerged as an international challenge which is compelling the community to trace out some smart solutions on priority basis. Corrosion mitigation is not only important as it results in wastage of our natural resources, time, money and efforts, but more importantly its inadequate handling may lead to the safety threats. Some, such sad incidents have been reported in the past. That is why many countries of the world are paying special attention to address this challenge by investing a lot of money. Although, we can notice corrosion everywhere around us, however, mining, mineral processing, oil & gas and many other processing industries are facing severe corrosion challenges. In many applications, it is only the surface of the material that is directly exposed to the corrosive medium, hence modifying the surface properties may lead to control the corrosion phenomenon. Towards this goal, the development of various types of nanocomposite coatings has proven to be a an economic and viable option. The present research work addresses the synthesis and characterization of novel Ni-B-AlN nanocomposite coatings. The Ni-B and Ni-B-AlN nanocomposite coatings were electrodeposited on the mild substrate. A comparison of structural, surface, mechanical and electrochemical properties are presented to elucidate the beneficial role of the incorporation of AlN nanoparticles into the Ni-B matrix. We have noticed that the addition of AlN nanoparticles to Ni-B matrix has a remarkable effect on its properties. Ni-B-AlN nanocomposite coatings demonstrate superior structural, mechanical and anticorrosion properties when compared to Ni-B coatings which make them attractive for many industrial applications.
Solar Thermal System for Heating and Cooling Requirements of Commercial Building in Doha: A Case Study
Authors: Khan shoukat alim , Aziz Majid , Koc Muammer
Published: June 2019

The demand for cooling in Gulf region is the direct effect of its high atmospheric temperature. Around 60% of the electricity demand in GCC is for cooling purpose. The main source of cooling and air-conditioning in these countries are conventional electric compression cycle, which leads to the increase in the GHG emission, directly in the form of leaked gases from these systems and indirectly in the form of fossil fuel used for the production of the used electricity for these systems. Solar energy in general and solar thermal energy specifically can be a promising and sustainable solution to the cooling and air-conditioning requirement for the buildings in Qatar and GCC. Absorption cooling and air-conditioning is a mature and promising technology with respect to its efficiency and results on the industrial scale. However, the use of technology with solar thermal energy is new in the market. In this paper, the feasibility analysis of solar thermal technology has been done for the cooling, heating and hot water requirement of a commercial building in Doha, Qatar. Heating and hot water requirement for winter and cooling requirement for summer season were calculated and used as a load. Solar thermal collectors (STC) were used as the main source of thermal energy collection form sunlight. Along with STC, thermally driven adsorption chiller was designed to fulfill the cooling requirement in the summer season. The design and selection of the different components and parameters such as Solar thermal collector area, storage tank size, adsorption chiller etc. have been done in detail. The result, obtained for building's energy demand and its supply from the designed solar thermal system, gives a clear sign for the successful implementation of this technology.
Production of hazardous gas sensors using spinel ferrite nanoparticles
Authors: Ayesh Jocelyn , Haija Mohammad Abu
Published: June 2019

This work reports on sensitive and selective gas sensors based on copper ferrite (CuFe2O4) nanoparticles. The nanoparticles were produced different methods including: colloid microwave assisted hydrothermal method, and co-precipitation method. Those methods enable a precise control of nanoparticle size, The produced nanoparticles were annealed at different temperatures. Structural analysis were carried out using x-ray diffraction (XRD) and transmission electron microscopy (TEM), and they revealed that the asprepared nanoparticle exhibit cubic structure. The nanoparticles undergo crystal structure transformation to tetragonal structure upon annealing. Furthermore, the nanoparticle were found to grow in size upon annealing. The tetrahedral and octahedral absorption bands which are characteristic of the spinel ferrite were determined using Fourier Transform Infra-Red Spectroscopy (FTIR) measurements. Gas sensors were fabricate by pressing the produced nanoparticle powder into disks. The sensor device was produced utilizing capacitor structure, with the top electrode stainless steel of grid structure. The produced sensors were characterized to be sensitive to both H2S and H2 gases, with greater sensitivity to H2S at low temperatures, where these sensors could detect H2S concentrations of 10 ppm at 80°C. The low optimal operation temperature reveals the low power requirements for sensor operation. Thus, those sensors exhibit the potential to be used for industrial applications, especially for the petrochemical industry the Petroleum Institute under a grant number RIFP-14312 and Qatar University.
Immobilized Nanosize ZrMetal Organic Frameworks ZrMOFs: Highly Active Reusable Catalysts for Cross Coupling Reactions
Authors: Elumalai Palani
Published: June 2019

Functionalized Zr-based metal-organic frameworks (UiO-66-fun) have emerged as promising class of porous functional materials with very large specific surface area, ultrahigh porosity and chemical tunability as well as high stability in water and humid environments, which results in desirable properties for several catalytic applications.1–3 These high stable materials were selected as supporting molecular MOF catalysts. We have applied a simple and highly efficient method for synthetic post-functionalization of new and readily recoverable molecular catalysts that combines the catalytic active transition-metal complexes with the architecture of nano-size MOF and their application for cross coupling reactions. In the catalytic process, substituted aryl halides and arylboronic acids converted into corresponding biaryls through C-C bond forming process in a milder condition (Chart 1). In the tested catalysis reactions, functionalized nano-size UiO-66-fun catalysts can be recovered by simple filtration/centrifugation in air and reusable without significant loss of catalytic activity and while framework structures are maintained stable. The detailed post-functionalization and catalysis results will be presented. References: Kim, M.; Cahill, J. F.; Fei, H.; Prather, K. A.; Cohen, S. M. J. Am. Chem. Soc. 2012, 134, 18082.Bosch, M.; Yuan, S.; Rutledge, W. Zhou, H.-C. Acc. Chem. Res. 2017, ASAP, DOI: 10.1021/acs.accounts.6b00457. Pascanu, V.; Yao, Q.; Bermejo Gomez, A.; Gustafsson, M.; Yun, Y.; Wan, W.; Samain, L.; Zou, X.; Martin-Matute, B. Chem. - Eur. J. 2013, 19, 17483. Acknowledgment: Support of this research by the NPRP award (NPRP 9-377-1-080) from the Qatar National Research Fund.
Developing an ecofriendly approach to reduce the use of biocides for preventing Microbial Induced Corrosion
Authors: Rasool Saad
Published: June 2019

Sulfate Reducing Bacteria (SRB) cause significant damage to marine oil pipelines necessitating the use of biocides for reducing the Microbial Induced Corrosion (MIC) and potential for great environmental harm. Currently, oil companies pump frequent batches of biocides to these under water pipelines without proper quantification of the bacterial population. This is primarily because the existing method for quantifying the bacterial population in a sample is not very effecient, as it can take up to 2 weeks to obtain the results. Our team has focused on developing an eco-friendly approach to limit the use of these biocides, which are used for targeting the SRB. SRB require high salt and low oxygen so first we genetically engineered a strain of bacteria that would report the osmolarity in oil pipelines, thus act as a biosensor for salt concentrations. The ratio of salinity in the seawater flowing in versus the seawater flowing out of the well will be used to estimate SRB populations in the pipelines, thus limiting the amount of biocides added in times of high Microbial counts.
NASICON based Na4MnV PO4 3/MWCNTs Cathode Materials for Naion Batteries with Improved Electrochemical Performance
Authors: Essehli Rachid , Nisar Umair , Alashraf Abdullah , Alqaradawi Siham Yousuf A , Kahranamn Ramazan , Shakoor R. A.
Published: June 2019

Lithium ion batteries (LIBs) have completely captured the portable electronics and electric vehicle market due to their tempting performance. However, due to limited reserves of lithium, the price for lithium is constantly increasing which necessitates to trace out some decent alternative to lithium ion batteries. In this regard, sodium ion batteries are considered one of the best substitutes for lithium ion batteries due to inherited properties of sodium metal like abundance of resources across the globe, ease of availability, economy and environmentally friendly nature. Moreover, sodium ion batteries follow the similar electrochemical principles as the lithium ion batteries which indicates that knowledge and understanding of principles of lithium ion batteries can be utilized for the development of smart sodium ion batteries. In this work NASICON (Na+ super ionic conductor) based Na4MnV (PO4) 3 was synthesized using the sol - gel technique. As prepared Na4MnV (PO4)3 demonstrates an active redox couple at around 3.6 V and 3.2 V during oxidation and reduction process respectively. The pristine Na4MnV(PO4)3 shows good initial discharge capacity ∼ 138 mAh g-1 at 0.05C. However, it shows rapid discharge capacity fading with increasing discharge rate (138 mAh/g at 0.05C and 15 mAh/g at 2C) and poor cycling performance (68.0% of the initial capacity was retained after 40 cycles) with increasing discharge rate. To improve the electrochemical performance of the developed material, Na4MnV (PO4)3/MWCNTS (MWCNTs = 1 & 3wt. %) were synthesized. The initial discharge capacity of these materials at 0.05C was found to be similar to pristine Na4MnV(PO4)3, however, the addition of MWCNTs has resulted in significant improvement in the discharge capacity at high c-rate which can be mainly attributed to the enhanced electronic conductivity of the pristine material. Apart from higher capacity at high c-rates, the addition of MWCNTs has also improved the cyclability of the pristine Na4MnV(PO4)3. A capacity retention of 99.0 % and 98.00% of the initial discharge capacity after 40 cycles is noticed for Na4MnV(PO4)3/1wt.%MWCNTs and Na4MnV(PO4)3/3wt.%MWCNTs respectively. The improved performance of Na4MnV (PO4) 3/MWCNTs cathode materails make them attractive for energystorage applications.
Improve the production of two Qatari date palm cultivars ShiShy and Lulu for food security
Authors: Ahmad Sara Aqeel
Published: June 2019

The response of plant tissue to standard growth media varies widely due to the genetic diversity of the plant cultivars studied. The objective of this research was to determine the effects of micronutrients on date palm growth and which of these micronutrients are critical for improving growth combined with Paclobutrazol or without on in vitro of elongation stage. In vitro growth of two cultivars was determined by varying five treatments that included minor salts (EDTA-chelated iron, Cuso4,) alone or combined with Paclobutrazol. The effects of these five treatments of plantlet length, trunk thickness, rooting number and Chlorophyll A, B were investigated. The results obtained after three months showed that, increase copper sulphate on MS elongation media combined with Paclobutrazol was more effective for increasing strongly of trunk thickness as well as rooting number compared with normal MS level. While poor response was found when increase of Fe in the chelated form of Fe-EDTA on MS elongation media. For cultivars, shishy gave the highest plantlets length as well as root number, while the increase of trunk thickness was achieved with cultivar LuLu. The greatest formation of chlorophylls A, B was observed when increase copper sulphate on MS elongation media with cultivar LuLu. The survival rate after 3 months was related to the medium used during the elongation phase, the survival of plantlets reached to 98.66% with cultivar lulu at the acclimatization stage.
Establishment of an Efficient in Vitro Regeneration Protocol for Mass Propagation via organogenesis of Endangered Plant Rhanterium epapposum in Qatar
Authors: Ibrahim Fatima hassan , Alhenzab Maha Talib , Elbadawi amira Omer
Published: June 2019

Wild plants make an important contribution to the life of localcommunities. Endangered plant species like Rhanterium epapposum olive (Arfaj) were micropropogated through tissue culture technique in order toprotect them from extinction and conserving Biodiversity in Qatar. Agriculture Research Department (ARD) has developed anefficient protocol for rapid and large scale in vitro propagation of the nativeannual plants Rhanterium epapposum that cannot be propagated on alarge-scale by means of seeds and cuttings. Apical bud and nods were collectedfrom wild habitat and cultured on modified Murashige and Skoog (MS) mediumsupplemented with 1.5 mg l-1 BA (initiation stage) and containing 1 mg l-1 BAP+0.2 mg l-1 Kinetin for multiplication stage, reculture three times withregular transferring to fresh medium containing the same composition medium.For rooting stage, elongated shoots were cultured on differentstrength of Murashige and Skoog (MS) media(full and ½) supplemented with different auxin. ½ MS nutrient medium containing1 mg l-1 IBA increased significantly the number of roots and root length compared with othertreatments. The plantlets were adapted to greenhouse conditions successfully