bluuebunny/crossref_metadata_2025_split huggingface dataset:
El uso de materiales audiovisuales y recursos digitales en la docencia universitaria: una experiencia de innovación a nivel de posgrado
Authors: Ames Ramello P.P. 
Published: June 2019

<p>Este artículo presenta una experiencia de innovación docente realizada en la Pontificia Universidad Católica del Perú en el año académico 2016 en el marco de una maestría en antropología. Se propuso: 1) incorporar materiales audiovisuales en todas las clases sobre los temas del curso; 2) incentivar el uso de la plataforma de aprendizaje PAIDEIA (Moodle) para el trabajo y evaluación de los estudiantes a lo largo del curso y para la gestión de los recursos audiovisuales, digitales y bibliográficos empleados en el curso; 3) ofrecer la opción de presentar el trabajo final del curso en formato audiovisual. La evaluación utilizó métodos tanto cualitativos como cuantitativos, como encuestas y focus group. Los resultados muestran un impacto positivo del uso de audiovisuales en las clases en tanto estos se combinaban con recursos bibliográficos y exposiciones, fomentando una mayor participación y reflexión de parte de los alumnos, y una mayor conciencia de su propio aprendizaje. Los estudiantes valoraron positivamente el uso de la plataforma PAIDEIA, desconocida para la mayoría de ellos, y aprendieron a utilizarla. Asimismo, produjeron materiales audiovisuales que reflejaban sus aprendizajes y que se convirtieron a su vez en material para otros cursos.</p>
Application of calixpyrrole modified silica for the removal of 4-chlorophenol from aqueous media
Authors: Abbas Ismail Ibrahim , El Hamaoui Bassem Mohamad Riad , Najmeddine Hilal Mohamad Jamal 
Published: June 2019

In this research, calixpyrrole modified silica (III) was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) techniques. The synthesized material was used as an extractant for the removal of 4-chlorophenol from aqueous solution. Its efficiency was examined through both batch and column extraction methods. The effects of temperature, pH, initial chlorophenol concentration and mass of the adsorbent were examined using removal efficiencies. Initial concentration and quantity of adsorbent show a noticeable influence on the uptake capacity of the adsorbent. The kinetics and thermodynamics of chlorophenol removal from aqueous media were also investigated. Kinetic studies indicated that the extraction data can be best represented by pseudo second order model. Column extraction data were analyzed through Thomas, Yoon-Nelson and Yan et al. models to calculate kinetic coefficients and maximum sorption capacity of the modified silica (III). The adsorbent silica was regenerated by acid treatment without changing its properties.
Synthesis and crystallographic structure of nickel(0) carbonyl complex with Bitianp, an atropoisomeric diphosphine
Authors: Fusè Marco , Facchetti Giorgio , Rimoldi Isabella , Castellano Carlo 
Published: June 2019

The reaction between an atropoisomeric diphosphine, Bitianp and [Ni(CO)4] was achieved by direct condensation in CH3Cl to afford complexes of general formula [Ni(CO)2(Bitianp)]. This compound was characterized by elemental analysis, IR, 1H-, 13C- and 31P-NMR spectroscopies. The structure of nickel complex has been determined by X-ray crystal-lography. Crystal data for C42H28NiO2P2S2 (M = 749.41 g/mol): triclinic, space group P-1 (no. 2), a = 10.539(2) Å, b = 11.811(2) Å, c = 15.994(3) Å, α = 83.93(3)°, β = 88.18(3)°, γ = 65.24(3)°, V = 1797.6(7) Å3, Z = 2, T = 294(2) K, μ(MoKα) = 0.781 mm-1, Dcalc =1.385 g/cm3, 22744 reflections measured (2.56° ≤ 2Θ ≤ 64.726°), 11837 unique (Rint = 0.0157, Rsigma = 0.0215) which were used in all calculations. The final R1 was 0.0360 (I > 2σ(I)) and wR2 was 0.1088 (all data). The coordination sphere of the Ni center is best described as a tetrahedral geometry.
Crystal structure and spectral studies of green fluorescent protein (GFP) chromophore analogue ethyl 2-[(4Z)-(6-hydroxy naphthalen-2-yl) methylene)-2-methyl-5-oxo-4,5-di hydro-1H-imidazol-1-yl] acetate
Authors: Puthuvakkal Anisha , Manoj Kochunnoonny 
Published: June 2019

Synthetically modified green fluorescent protein chromophore derivative was prepared, its crystal structure and spectral properties were studied. Crystal data for C19H18N2O4: triclinic, space group P-1 (no. 2), a = 8.2506(17) Å, b = 11.934(2) Å, c = 17.461(4) Å, α = 102.89(3)°, β = 94.62(3)°, γ = 96.68(3)°, V = 1654.5(6) Å3, Z = 4, T = 173(2) K, μ(MoKα) = 0.096 mm-1, Dcalc = 1.358 g/cm3, 7227 reflections measured (4.722° ≤ 2Θ ≤ 53.996°), 7227 unique (Rint = 0.0453, Rsigma = 0.0662) which were used in all calculations. The final R1 was 0.0561 (I > 2σ(I)) and wR2 was 0.1658 (all data). The single crystal structure showed, the benzylidine moiety adopts Z-conformation in solid state and the molecules were associated by various O−H···O and C−H···O non-covalent interactions. The UV absorption-emission spectral analysis indicated that a significant red shift of emission observed at alkaline pH indicating its utility for live cell imaging applications.
Optimization of engineering student learning and assessment by cognitive methods
Authors: Taylan Osman , Rizwan Ali , Parsaei Hamid 
Published: June 2019

This study addresses the learning objectives and the student outcomes of industrial engineering students by examining them at three different levels: course level, program level, and graduate level. Three learning domains are developed and analyzed for this purpose to assess the performance of students during and after graduation. These domains are labeled as the house of cognitive learning, which shows the level of learning, its outcome elements, and the depth of understanding.
In the higher education system, the correct assessment of student learning is always considered as a challenging task. The aim of this study was to develop an integrated integer-programming algorithm to accurately determine the learning level of students. The method incorporates quality control charts and statistical assessment tools to present the findings. In this study, level of learning is calculated as a learning index that presents the contribution of a course to the respective student outcomes. Moreover, it depicts the overall achievements of students during their learning. Therefore, another aim of this study was to explore how to better utilize the collected data for the assessment of learning level. The outcomes of algorithm and statistical approaches are quite encouraging for the evaluation of students' learning, thus improving the quality of engineering program.
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.
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).
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.
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 &amp; 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.
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
Efficient and fast separation of emulsified oil/water mixtures with a novel micro/nanofiber network membrane
Authors: Liu Zhaoyang 
Published: June 2019

Produced water is one of the largest waste streams emanating from oil and gas industries. If inadequately treated, emulsified oil droplets contained in produced water will contaminate the environment and subsequently pose severe threat to human health. Removal of tiny emulsified oil droplets in produced water is very challenging. In this study, we demonstrated a new concept for constructing oil/water separating membranes with ultra-long titanate nanofibers (over 30 μm in length) / cellulose microfibers. An integrated network membrane was achieved with these ultra-long micro/nanofibers. This new membrane demonstrates good mechanical flexibility, which are critical for practical applications. This membrane shows high separation efficiency (99.9%) for oil/water emulsions with oil droplet size down to 3 μm, and at the same time has high water permeation flux (6.8 × 104 L m-2 h-1 bar-1) at low operation pressure. The high water flux is attributed to the interconnected porous structure throughout the whole membrane, while the nanoporous selective layer contributes to high oil separation. In addition, the low-cost materials and fabrication process for this membrane suggests its great potential for industrial scale-up.
Efficient Inhibition of SulfateReducing Bacteria in Inject Sea Water by “Green” Chitosan/ZnO nanocomposite
Authors: Rasool Kashif 
Published: June 2019

Oil producing companies utilize water injection as a common oil recovery method for decades, especially for offshore fields, where seawater is typically used as inject water. Due to the size and complexity of the injection system and the high salinity of the water (∼55,000 mg/L); several challenges are faced during this process including microbial growth, fouling and corrosion in the pipeline. Biofilms accelerate corrosion in a biologically conditioned metal–solution interface. Oil producing companies including those in Qatar use biocides to disinfect the water and inhibit biofilm formation caused mainly by sulfate reducing bacteria (SRB). However, traditional biocides may induce bacterial resistance and/or be detrimental to environment. In this study we synthesized chitosan/ZnO nanocomposite (CZNCs) and evaluated its antimicrobial activity against SRB biofilm in inject seawater. CZNCs showed stable behavior when exposed to higher salt concentrations of inject water. The inhibition of SRB activity was concentration-dependent and more than 73% and 43% inhibition of sulfate reduction and TOC removal, respectively, was observed at 250 μg/mL CZNCs at 10% initial ZnO loading. Scanning electron microscopy (SEM) coupled with lactate dehydrogenase (LDH) release assay indicated obvious damages to the cellular membrane which resulted in release of cytoplasmic materials from the bacterial cells. Significant decrease in concentration of EPS extracts was obtained. This work has demonstrated that the exposure of synthesized CZNCs could cause significant SRB anti-biofouling properties. This is the first ever study of antimicrobial potential of chitosan based biocides for SRB inhibition. We are confident that this work will make the scientific as well as the industrial communities to appreciate the application of nanomaterials based biocides. This is the first ever study of antimicrobial potential of any ENM generally, and chitosan based biocides, particularly, for SRB enriched biofilm inhibition. Taking into account tremendous interest to nanomaterials as antimicrobial agents, we anticipate a major impact from a much better material reported in his paper.