cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Laser Induced Ablation and Doping Processes on High Efficiency Silicon Solar Cells
Creators: name: Morilla, C.
name: Russell, R.
name: Fernandez, J.M.
Publisher: name: WIP-Munich
Year: 2008
Subjects: Wafer-Based Silicon Solar Cells and Materials Technology
Mono- and Multicrystalline Silicon Cells and Materials, Processing Technology of

description: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 1506-1509
description: Selective ablation and doping are processes common in crystalline silicon solar cell manufacturing intended to reduce the contact resistance between the metal and silicon and to enhance the blue response of the cells by means of a lightly doped emitter combined to a heavy doped contact area. These processes can particularly take advantage of the usage of laser technology since it enables the possibility to substitute high temperature furnace driven processes by low thermal budget, locally selective and highly flexible processes offered by lasers.
One of the key points in transferring laser processes into production is the selection of the most adequate laser source and processing conditions. In this work we focus on the development of a laser assisted process of simultaneous ablation and doping for high efficiency crystalline silicon solar cells. Detailed process characterisation has been carried out as a function of different laser parameters. Evaluation of the sheet resistance of the doped area and dimensional and microstructural characterisation of laser transformed areas have been carried out for different process configurations. The impact of laser induced damage on the cell performance has been evaluated and strategies to minimise it are suggested.
Delineating and preventing plastic waste leakage in the marine and terrestrial environment
Creators: name: Hahladakis, John N.
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Environmental engineering
subject: FOS: Environmental engineering
subject: Pollution and contamination

description: Plastics are nowadays considered to be the workhorse material of our modern society with an ubiquitous presence that has increased manifold over the past 60 years, providing several benefits to the global economy. However, inappropriate and/or uncontrolled disposal practices, poor waste management infrastructure and application of insufficient recycling technologies, coupled with a lack of public awareness and incentives, have rendered plastic waste omnipresent, littering both the marine and the terrestrial environment with multi-faceted impacts. This short communication/commentary aims at delineating the plastic litter global challenge providing, at the same time, scientific views and perspectives on properly dealing with this material type, both upstream and downstream.Other Information Published in: Environmental Science and Pollution Research
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11356-020-08139-y
Cadmium-induced endothelial dysfunction mediated by asymmetric dimethylarginine
Creators: name: Al-Naemi, Hamda A.
name: Das, Sandra Concepcion
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Environmental engineering
subject: FOS: Environmental engineering
subject: Pollution and contamination

description: Cadmium (Cd) is a naturally occurring toxic heavy metal with no known essential biological functions. Exposure to Cd increases the risk of cardiovascular disease by disrupting vascular homeostasis at the endothelium. The aim of the study was to evaluate the effect of chronic low-dose Cd on vascular structure and function. Fifty adult male Sprague Dawley rats were grouped and assigned to one of two treatments for 14 weeks. The control group received normal water for 14 weeks while the Cd-treated group received 15 mg Cd/kg B.W. as CdCl2 in water for 10 weeks. A subset of the Cd-treated group received 15 mg Cd/kg B.W. as CdCl2 in water for 10 weeks followed by 4 weeks of normal water. Results show an overall decline in vascular function and structure. Withdrawal of Cd treatment showed a considerable restoration of vascular structure and vasorelaxation function. Additionally, asymmetric dimethylarginine (ADMA) bioavailability was found to be lowered over time. Interestingly, the expression of eNOS in the Cd-treated group was found to be significantly elevated during the exposure by more than 3-fold in comparison with that in the control group. This protein expression was similar to the control group after the withdrawal of Cd treatment. Taken together, the results suggest that ADMA, an eNOS inhibitor, may play a role in altering endothelial function in the presence of cadmium. In conclusion, the findings indicate that even at low doses, Cd leads to endothelial dysfunction mediated by ADMA.Other Information Published in: Environmental Science and Pollution Research
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11356-020-08116-5
Comparison of Measurement and Simulation of Charge Transport in Selective Energy Contacts Based on Si Quantum Dots
Creators: name: Suckow, S.
name: Berghoff, B.
name: Spangenberg, B.
name: Kurz, H.
Publisher: name: WIP-Munich
Year: 2009
Subjects: Advanced Photovoltaics
Fundamental Studies

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 545-547
description: The current through a resonant tunneling diode consisting of Si quantum dots embedded in a SiO2
matrix is calculated, including the resonance broadening effects due to distributions of quantum dot diameter and
asymmetric barrier thicknesses. The results are in good agreement with experimental data and allow deductions
regarding the physical sample structure. The quantum dot size distribution is identified as a major obstacle for the
usage of these layers as selective energy contacts in hot carrier solar cells.
Carboxylate based molecular magnet: one path toward achieving stable quantum correlations at room temperature
Creators: name: Cruz, C.
name: Soares-Pinto, D. O.
name: Brandao, P.
name: Santos, A. M. dos
name: Reis, M. S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The control of quantum correlations in solid state systems by means of material engineering is a broad avenue to be explored, since it makes possible steps toward the limits of quantum mechanics and the design of novel materials with applications on emerging quantum technologies. In this context, this Letter explores the potential of molecular magnets to be prototypes of materials for quantum information technology. More precisely, we engineered a material and from its geometric quantum discord we found significant quantum correlations up to 9540 K (even without entanglement); and, in addition, a pure singlet state occupied up to around 80 K (above liquid nitrogen temperature). These results could only be achieved due to the carboxylate group promoting a metal-to-metal huge magnetic interaction.
Analytical Research of the Acid Etching Bath by Ion Chromatography
Creators: name: Oltersdorf, A.
name: Zimmer, M.
name: Seitz, M.
name: Rentsch, J.
Publisher: name: WIP-Munich
Year: 2008
Subjects: Wafer-Based Silicon Solar Cells and Materials Technology
Mono- and Multicrystalline Silicon Cells and Materials, Processing Technology of

description: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 1488-1492
description: In the photovoltaic and microelectronic processing of silicon the isotropic chemical etching with HNO3 and HF is used to clean the surface from contaminations, to remove the saw damage, as well as to polish or to texture the wafer surface. Within this study the influence of varying concentrations of HF, HNO3 and especially H2SiF6 on the topology of the wafer surface and the resulting etch rate is presented. For an effective etch process control it is important to know the actual etching bath composition in order to maintain a certain etching rate by replenishment of the consumed acids. In the paper an
analytical method that is suitable for online analysis of the etching bath constituents HF, HNO3 and H2SiF6 is introduced. The method is based on ion chromatography, the anions are detected by suppressed conductivity and a post-column derivatization allows the detection of silicon by visible absorbance.
Impact-induced Formation of Prebiotic Molecules on Terrestrial Planets
Creators: name: Zorzi, Andrea
name: Schaefer, Laura K.
Publisher: name: Zenodo
Year: 2023

description: New chemical species can form from reactions induced by shock-heating upon formation of an impact vapor plume and its interaction with the background atmosphere of a rocky planet. Previous studies have assumed chemical equilibrium in computing the abundance of chemical species: such a simplified model can underestimate those concentrations by a factor of 10 in high temperature shock conditions. A more accurate description of the plume/atmosphere interaction demands a coupled hydrodynamics and kinetics calculation. We present a new model extending the work of Ishimaru et al. (2010) by considering an atmosphere on the target planet. We assess the production of prebiotic molecules (HCN, CH4, NH3) for different impact scenarios, varying kinetic energy of the impactor, atmospheric surface density and composition. We find that prebiotic species are produced on Earth-like planets with a N2-CH4 atmosphere, with increasing abundance when: i) the atmospheric surface density increases; ii) the impact energy decreases; iii) the amount of methane in the pre-existing atmosphere increases. The presence of oxygen in today's inner solar system planets prevents the production of HCN. On Titan, impacts can constitute an additional sink for methane. Our findings provide necessary but not sufficient conditions for prebiotic chemistry to start, to assess the astrobiological potential of impacts on terrestrial worlds.
Accurate Reaction-Diffusion Operator Splitting on Tetrahedral Meshes for Parallel Stochastic Molecular Simulations
Creators: name: Hepburn, I.
name: Chen, W.
name: De Schutter, E.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantitative Methods (q-bio.QM)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Biological Physics (physics.bio-ph)
subject: Chemical Physics (physics.chem-ph)
subject: Biomolecules (q-bio.BM)
subject: FOS: Biological sciences
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Spatial stochastic molecular simulations in biology are limited by the intense computation required to track molecules in space either in a discrete time or discrete space framework, meaning that the serial limit has already been reached in sub-cellular models. This calls for parallel simulations that can take advantage of the power of modern supercomputers; however exact methods are known to be inherently serial. We introduce an operator splitting implementation for irregular grids with a novel method to improve accuracy, and demonstrate potential for scalable parallel simulations in an initial MPI version. We foresee that this groundwork will enable larger scale, whole-cell stochastic simulations in the near future.
description: 33 pages, 10 figures
Spectroscopic Ellipsometry Analysis of Silicon-Rich Silicon Nitride Layers for Photovoltaic Applications
Creators: name: Delachat, F.
name: Carrada, M.
name: Ferblantier, G.
name: Slaoui, A.
name: Keita, A.-S.
name: En Naciri, A.
name: Kloul, M.
name: Gaston, J.P.
Publisher: name: WIP-Munich
Year: 2009
Subjects: Advanced Photovoltaics
Fundamental Studies

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 520-523
description: Silicon-rich silicon nitride (SRN) layers can be of great interest for 3rd generation solar cells. Indeed
such materials can be used as luminescent converters to enhance photovoltaic conversion in the blue region of the
spectrum or as high band-gap material for an all Si tandem cell concept. For the first application, the light converter
film could be part of the antireflection coating layer where some Si nanoparticles (Si-nps) with controlled size and
density are embedded. For the tandem concept, a superlattice composed of nano-size silicon nitride (SiN) layers
containing Si-nps has to be produced. High resolution TEM and room temperature photoluminescence are often used
for witnessing the formation of the Si-nps. On the other hand spectroscopic ellipsometry (SE) technique was
thoroughly applied to characterize the optical properties of SiN layers.
This work aims at using the spectroscopic ellipsometry tool to estimate the optical (band gap) and structural (size,
density) properties of Si-nps embedded in SRN layers.
Virtual crystal description of III-V semiconductor alloys in the tight binding approach
Creators: name: Nestoklon, M. O.
name: Benchamekh, R.
name: Voisin, P.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We propose a simple and effective approach to construct the empirical tight-binding parameters of ternary alloys in the virtual crystal approximation. This combines a new, compact formulation of the strain parameters and a linear interpolation of the hamiltonians of binary materials strained to the alloy equilibrium lattice parameter. We show that it is possible to obtain a perfect description of the bandgap bowing of ternary alloys in the InGaAsSb family of materials. Furthermore, this approach is in a good agreement with supercell calculations using the same set of parameters. This scheme opens a way for atomistic modeling of alloy-based opto-electronic devices without extensive supercell calculations.
description: 4 pages, 3 figures
Curve Template for the I-V Characteristics of the Solar Cells
Creators: name: Fejfar, A.
Publisher: name: WIP-Munich
Year: 2009
Subjects: Advanced Photovoltaics
Fundamental Studies

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 557-558
description: The contribution describes a computer program for manual fitting of the solar cell current dependence
on voltage. The inspiration was drawn from French curve templates which use a flexible plastic to approximate
various curves. In the present case the template follows the solar cell equation and provides handles ‘attached’ to the
curve for intuitive manipulation of the parameters. The template may be used to get a quick estimate of the
parameters for the given experimental points or to judge sensitivity of the fit to the individual parameters.
Powerful Activity in the Bright Ages. I. A Visible/IR Survey of High Redshift 3C Radio Galaxies and Quasars
Creators: name: Hilbert, Bryan
name: Chiaberge, Marco
name: Kotyla, JohnPaul
name: Tremblay, Grant R.
name: Stanghellini, Carlo
name: Sparks, William B.
name: Baum, Stefi A.
name: Capetti, Alessandro
name: Macchetto, F. Duccio
name: Miley, George K.
name: O'Dea, Christopher P.
name: Perlman, Eric S.
name: Quillen, Alice C.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present new rest frame UV and visible observations of 22 high-redshift (1 < z < 2.5) 3C radio galaxies and QSOs obtained with the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3) instrument. Using a custom data reduction strategy in order to assure the removal of cosmic rays, persistence signal, and other data artifacts, we have produced high-quality science-ready images of the targets and their local environments. We observe targets with regions of UV emission suggestive of active star formation. In addition, several targets exhibit highly distorted host galaxy morphologies in the rest frame visible images. Photometric analyses reveals that brighter QSOs tend to be generally redder than their dimmer counterparts. Using emission line fluxes from the literature, we estimate that emission line contamination is relatively small in the rest frame UV images for the QSOs. Using archival VLA data, we have also created radio map overlays for each of our targets, allowing for analysis of the optical and radio axes alignment.
description: 25 pages, 54 figures; Accepted for publication in ApJS
Efficient oil/saltwater separation using a highly permeable and fouling-resistant all-inorganic nanocomposite membrane
Creators: name: Elshorafa, Rand
name: Saththasivam, Jayaprakash
name: Liu, Zhaoyang
name: Ahzi, Said
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Environmental engineering
subject: FOS: Environmental engineering
subject: Pollution and contamination

description: Although it is still a great challenge, developing oil-/water-separating membranes that combine the advantages of high separation efficiency, salty environments tolerance, and fouling resistance are highly demanded for marine oil spill cleanups and oil-/gas-produced water treatment. Here, we report a new type of all-inorganic nanostructured membrane, which is composed of titanate nanofibers and SiO2 particulate gel for efficient and stable oil/saltwater separation. The nanoporous and interconnected network structure constructed with titanate nanofibers is the key to ensure the high separation efficiency and high water flux of the new membrane. The SiO2 gel is used as a binder to offer mechanical flexibility and integrity for this type of all-inorganic membrane. The new membrane displays a high oil/water separation efficiency of above 99.5% with oil content in treated effluent lower than US environmental discharge standards (42 ppm) and high water permeation flux of 1600 LMH/bar under low operation pressure. The new membrane also demonstrates outstanding durability in the environment of different salinities, and it has a good resistance for oil fouling due to its excellent underwater superoleophobicity with an oil contact angle above 150 °. Most importantly, the underwater superoleophobic properties can be well maintained after being repeatedly reused. The excellent environmental durability, oil-fouling resistance, high separation efficiency, and facile fabrication process for this new type of membrane render great potential for industrial application in treating produced water.Other Information Published in: Environmental Science and Pollution Research
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11356-020-08021-x
Nanomagnetic logic with non-uniform states of clocking
Creators: name: Puliafito, Vito
name: Giordano, Anna
name: Azzerboni, Bruno
name: Finocchio, Giovanni
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Nanomagnetic logic transmits information along a path of nanomagnets. The basic mechanism to drive such a transmission, known as clocking, can be achieved by exploiting the spin-Hall effect, as recently observed in experiments on Ta/CoFeB/MgO multilayers [D. Bhowmik, et al., Nat. Nano. 9, 59 (2013)]. This paper shows the fundamental mechanism of the spin-Hall driven clocking by using a full micromagnetic framework and considering two different devices, Ta/CoFeB/MgO and Pt/CoFeB/MgO. The former is used for a direct comparison of the numerical results with the experiments while the latter permits to predict the effect of the Dzyaloshinskii-Moriya interaction (DMI) in the clocking mechanism. Results show that the clocking state is non-uniform and it is characterized by the presence of domains separated by Bloch (Néel) domain walls depending on the absence (presence) of the DMI. Our findings point out that for the design of nanomagnetic logic a full micromagnetic approach is necessary.
description: 12 pages, 3 figures
Effects of dissolved organic phase composition and salinity on the engineered sulfate application in a flow-through system
Creators: name: Shafieiyoun, Saeid
name: Al-Raoush, Riyadh I.
name: Ismail, Reem Elfatih
name: Ngueleu, Stephane K.
name: Rezanezhad, Fereidoun
name: Van Cappellen, Philippe
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Environmental engineering
subject: FOS: Environmental engineering
subject: Pollution and contamination

description: Engineered sulfate application has been proposed as an effective remedy to enhance the rate-limited biodegradation of petroleum-hydrocarbon-contaminated subsurface environments, but the effects of dissolved organic phase composition and salinity on the efficiency of this method are unknown. A series of flow-through experiments were conducted for 150 days and dissolved benzene, toluene, naphthalene, and 1-methylnaphthalene were injected under sulfate-reducing and three different salinity conditions for 80 pore volumes. Then, polycyclic aromatic hydrocarbons (PAHs) were omitted from the influent solution and just dissolved benzene and toluene were injected to investigate the influence of dissolved phase composition on treatment efficiency. A stronger sorption capacity for PAHs was observed and the retardation of the injected organic compounds followed the order of benzene < toluene < naphthalene < 1-methylnaphthalene. Mass balance analyses indicated that 50 and 15% of toluene and 1-methlynaphtalene were degraded, respectively. Around 5% of the injected naphthalene degraded after injecting > 60 PVs influent solution, and benzene slightly degraded following the removal of PAH compounds. The results showed substrate interactions and composition can result in rate-limited and insufficient biodegradation. Similar reducing conditions and organic utilization were observed for different salinity conditions in the presence of the multi-component dissolved organic phase. This was attributed to the dominant microbial community involved in toluene degradation that exerted catabolic repression on the simultaneous utilization of other organic compounds and were not susceptible to changes in salinity.Other Information Published in: Environmental Science and Pollution Research
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11356-020-07696-6
Current-induced Pinwheel Oscillations in Perpendicular Magnetic Anisotropy Spin Valve Nanopillars
Creators: name: Choi, Richard
name: Katine, J. A.
name: Mangin, Stephane
name: Fullerton, Eric E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Nanopillar spin valve devices are typically comprised of two ferromagnetic layers: a reference layer and a free layer whose magnetic orientation can be changed by both an external magnetic field and through the introduction of spin-polarized electric current. Here we report the continuous repeated switching behavior of both the reference and free layers of a perpendicular spin valve made of Co/Pd and Co/Ni multilayers that arises for sufficiently large DC currents. This periodic switching of the two layers produces an oscillating signal in the MHz regime but is only observed for one sign of the applied current. The observed behavior agrees well with micromagnetic simulations.
Enhanced Removal of Diesel Oil Using New Magnetic Bentonite-Based Adsorbents Combined with Different Carbon Sources
Creators: name: Ewis, Dina
name: Mahmud, Nafis
name: Benamor, Abdelbaki
name: Ba-Abbad, Muneer M.
name: Nasser, Mustafa
name: El-Naas, Muftah
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Pollution and contamination
subject: Chemical engineering
subject: FOS: Chemical engineering

description: In this work, new magnetic bentonite-based adsorbents combined with different carbon sources, namely, reduced graphene oxide and multiwall carbon nanotubes, were synthesized via co-precipitation method. The synthesized adsorbents were characterized using XRD, TGA, SEM, EDX, TEM, and BET analysis techniques. The adsorbents were then used to remove oil from aqueous solutions of water-in-oil emulsion by performing batch adsorption experiments. The experimental data were fitted to three isotherm models including Langmuir, Freundlich, and Sips models using non-linear regression and were compared using Akaike Information Criterion statistical model. The data analysis showed that Sips model best fits the experimental data for the adsorption of oil onto both adsorbents. The maximum adsorption capacity of oil from sips model were 81.65 mg/g and 77.12 mg/g for Fe3O4/Bent/rGO and Fe3O4//Bent/MWCNTs, respectively. The obtained kinetics data were fitted to pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Pseudo-second order kinetic model best fitted the kinetic data of both adsorbents. Overall, both adsorbents showed high removal efficiency reaching equilibrium in less than 50 min indicating that both adsorbents can be successfully utilized in industrial adsorption process. Graphical abstractOther Information Published in: Water, Air, & Soil Pollution
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11270-022-05641-6
Enhancement of Naphthalene Degradation by a Sequential Sulfate Injection Scenario in a (Semi)-Arid Coastal Soil: a Flow-Through Reactor Experiment
Creators: name: Shafieiyoun, Saeid
name: Al-Raoush, Riyadh I.
name: Ngueleu, Stephane K.
name: Rezanezhad, Fereidoun
name: Van Cappellen, Philippe
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Pollution and contamination
subject: Chemical engineering
subject: FOS: Chemical engineering

description: Engineered sulfate injection has been introduced as an effective technology to enhance the remediation of soil and groundwater contaminated by petroleum hydrocarbons. While some studies indicate that sulfate injection is a promising method for the treatment of hydrocarbon-contaminated subsurface systems, its application in the brackish soil environments is unknown. In this study, we explored related geochemical indicators along with soil adsorption and dissolved phase concentrations to provide an improved understanding of the hydrocarbon-contaminated subsurface responses to the sulfate injection in brackish environments. A series of flow-through experiments representing in situ groundwater anaerobic bioremediation were conducted and two sulfate injection episodes were applied to examine the degradation of dissolved naphthalene under low salinity and brackish conditions. As opposed to the substantial body of previous studies that salinity restricts biodegradation, the results from this study showed that naphthalene anaerobic degradation was more stable once the salinity was as high as that at the sampling location in the coastal brackish environment. While increasing naphthalene concentration from 4 to 12 mg L−1 did not limit biodegradation efficiency under brackish condition similar to the sampling location, it adversely restricted the developed reducing conditions and biodegradation process under low salinity conditions. This highlights the adaption of the microbial communities within the soil to the brackish environment at the sampling location suggesting that changing the salinity during engineered sulfate application can make the remediation process more susceptible against the environmental stresses and substrate toxicity. The results of this study provide insight into the engineered sulfate application as a remediation strategy for potential removal of dissolved naphthalene from the contaminated brackish groundwater.Other Information Published in: Water, Air, & Soil Pollution
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11270-020-04725-5
Modeling the effects of capillary pressure with the presence of full tensor permeability and discrete fracture models using the mimetic finite difference method
Creators: name: Abd, Abdul Salam
name: Zhang, Na
name: Abushaikha, Ahmad S.
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Physical chemistry
subject: Chemical engineering
subject: FOS: Chemical engineering

description: Capillary dominated flow or imbibition—whether spontaneous or forced—is an important physical phenomena in understanding the behavior of naturally fractured water-driven reservoirs (NFR’s). When the water flows through the fractures, it imbibes into the matrix and pushes the oil out of the pores due to the difference in the capillary pressure. In this paper, we focus on modeling and quantifying the oil recovered from NFR’s through the imbibition processes using a novel fully implicit mimetic finite difference (MFD) approach coupled with discrete fracture/discrete matrix (DFDM) technique. The investigation is carried out in the light of different wetting states of the porous media (i.e., varying capillary pressure curves) and a full tensor representation of the permeability. The produced results proved the MFD to be robust in preserving the physics of the problem, and accurately mapping the flow path in the investigated domains. The wetting state of the rock affects greatly the oil recovery factors along with the orientation of the fractures and the principal direction of the permeability tensor. We can conclude that our novel MFD method can handle the fluid flow problems in discrete-fractured reservoirs. Future works will be focused on the extension of MFD method to more complex multi-physics simulations.Other Information Published in: Transport in Porous Media
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11242-021-01585-3
On the Performance of the Node Control Volume Finite Element Method for Modeling Multi-phase Fluid Flow in Heterogeneous Porous Media
Creators: name: Abd, Abdul Salam
name: Abushaikha, Ahmad S.
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: subject: Physical chemistry
subject: Chemical engineering
subject: FOS: Chemical engineering

description: In this paper, we critique the performance of the node control volume finite element (NCVFE) method for modeling multi-phase fluid flow in heterogeneous media. The NCVFE method solves for the pressure at the vertices of elements and a control volume mesh is constructed around them. Material properties are defined on elements, while transport is simulated on the control volumes. These two meshes are not aligned producing inaccurate results and artificial fluid smearing when modeling multi-phase fluid flow in heterogeneous media. We perform numerical tests to quantify and visualize the extent of this artificial fluid smearing in domains with different material properties. The domains are composed of tetrahedron finite elements. Large artificial fluid smearing is observed in coarse meshes; however, it decreases with the increase in mesh resolution. These findings prompt the use of high-resolution meshes for the method and the need for development of novel numerical methods to address this unphysical flow.Other Information Published in: Transport in Porous Media
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11242-020-01481-2
Characteristics and comparisons of acute stroke in “recovered" to “active COVID-19 and “pre-pandemic” in Qatar database
Creators: name: Akhtar, Naveed
name: Abid, Fatma
name: Singh, Rajvir
name: Kamran, Saadat
name: Imam, Yahia
name: Al Jerdi, Salman
name: Salameh, Sarah
name: Al Attar, Rand
name: Yasir, Muhammad
name: Shabir, Hammad
name: Morgan, Deborah
name: Joseph, Sujatha
name: AlMaslamani, Muna
name: Shuaib, Ashfaq
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: Cardiovascular medicine and haematology
Public health

description: Understanding the relationship of COVID-19 to stroke is important. We compare characteristics of pre-pandemic stroke (PPS), cases in acute COVID infection (CS) and in patients who have recovered from COVID-19 infection (RCS). We interrogated the Qatar stroke database for all stroke admissions between Jan 2020 and Feb 2021 (PPS) to CS and RCS to determine how COVID-19 affected ischemic stroke sub-types, clinical course, and outcomes prior to, during and post-pandemic peak. There were 3264 cases admitted (pre-pandemic: 3111, stroke in COVID-19: 60 and recovered COVID-19 stroke: 93). Patients with CS were significantly younger, had more severe symptoms, fever on presentation, more ICU admissions and poor stroke recovery at discharge when compared to PPS and RCS. Large vessel disease and cardioembolic disease was significantly higher in CS compared to PPS or RCS. There was a significant decline in stroke mimics in CS. Stroke in RCS has characteristics similar to PPS with no evidence of lasting effects of the virus on the short-term. However, CS is a more serious disease and tends to be more severe and have a poor prognosis.Other Information Published in: Journal of Thrombosis and Thrombolysis
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11239-021-02581-6
Generic Superweak Chaos Induced by Hall Effect
Creators: name: Ben-Harush, Moti
name: Dana, Itzhack
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We introduce and study the "kicked Hall system" (KHS), i.e., charged particles periodically kicked in the presence of uniform magnetic ($\mathbf{B}$) and electric ($\mathbf{E}$) fields that are perpendicular to each other and to the kicking direction. We show that for resonant values of $B$ and $E$ and in the weak-chaos regime of sufficiently small nonintegrability parameter $κ$ (the kicking strength), there exists a \emph{generic} family of periodic kicking potentials for which the Hall effect from $\mathbf{B}$ and $\mathbf{E}$ significantly suppresses the weak chaos, replacing it by \emph{"superweak"} chaos (SWC). This means that the system behaves as if the kicking strength were $κ^2$ rather than $κ$. For $E=0$, SWC is known to be a classical fingerprint of quantum antiresonance but it occurs under much less generic conditions, in particular only for very special kicking potentials. Manifestations of SWC are a decrease in the instability of periodic orbits and a narrowing of the chaotic layers, relative to the ordinary weak-chaos case. Also, for global SWC, taking place on an infinite "stochastic web" in phase space, the chaotic diffusion on the web is much slower than the weak-chaos one. Thus, the Hall effect can be relatively stabilizing for small $κ$. In some special cases, the effect is shown to cause ballistic motion for almost all parameter values. The generic global SWC on stochastic webs in the KHS appears to be the two-dimensional closest analog to the Arnol'd web in higher dimensional systems.
Meta Classification for Variable Stars
Creators: name: Pichara, Karim
name: Protopapas, Pavlos
name: León, Daniel
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The need for the development of automatic tools to explore astronomical databases has been recognized since the inception of CCDs and modern computers. Astronomers already have developed solutions to tackle several science problems, such as automatic classification of stellar objects, outlier detection, and globular clusters identification, among others. New science problems emerge and it is critical to be able to re-use the models learned before, without rebuilding everything from the beginning when the science problem changes. In this paper, we propose a new meta-model that automatically integrates existing classification models of variable stars. The proposed meta-model incorporates existing models that are trained in a different context, answering different questions and using different representations of data. Conventional mixture of experts algorithms in machine learning literature can not be used since each expert (model) uses different inputs. We also consider computational complexity of the model by using the most expensive models only when it is necessary. We test our model with EROS-2 and MACHO datasets, and we show that we solve most of the classification challenges only by training a meta-model to learn how to integrate the previous experts.
description: Accepted for publication, The Astrophysical Journal
Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures
Creators: name: Horie, Yu
name: Arbabi, Amir
name: Arbabi, Ehsan
name: Kamali, Seyedeh Mahsa
name: Faraon, Andrei
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-Pérot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250 nm around λ = 1550 nm (Δλ/λ = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwiched metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling.
Simulations and Measurements for Indoor Photovoltaic Devices
Creators: name: Müller, M.
name: Hildebrandt, H.
name: Walker, W.D.
name: Reindl, L.M.
Publisher: name: WIP-Munich
Year: 2009
Subjects: PV Systems
Off-grid Applications and Rural Electrification

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 4363-4367
description: A reliable operation of an indoor photovoltaic (ipv) device requires the knowledge of the expected
irradiance. Available data on indoor irradiance, refer to single measurements and/or to values using the photometric
unit Lux. This study evaluates the performance of luxmeters depending on the light source, the use of the ray tracing
programs Radiance [1] and DAYSIM [2] in ipv-design, and radiometric measurement methods for low intensities to
validate the simulation results obtained. The authors present flexible and cost effective methods for ipv-designers to
determine reliable radiometric values of indoor irradiance.
HST-COS Observations of AGNs. III. Spectral Constraints in the Lyman Continuum from Composite COS/G140L Data
Creators: name: Tilton, Evan M.
name: Stevans, Matthew L.
name: Shull, J. Michael
name: Danforth, Charles W.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The rest-frame ultraviolet (UV) spectra of active galactic nuclei (AGNs) are important diagnostics of both accretion disk physics and their contribution to the metagalactic ionizing UV background. Though the mean AGN spectrum is well characterized with composite spectra at wavelengths greater than 912 Angstroms, the shorter-wavelength extreme-UV (EUV) remains poorly studied. In this third paper in a series on the spectra of AGNs, we combine 11 new spectra taken with the Cosmic Origins Spectrograph on the Hubble Space Telescope with archival spectra to characterize the typical EUV spectral slope of AGNs from $λ_{\rm rest}\sim 850~{\rm Angstroms}$ down to $λ_{\rm rest}\sim 425~{\rm Angstroms}$. Parameterizing this slope as a power law, we obtain $F_ν\propto ν^{ -0.72\pm 0.26}$, but we also discuss the limitations and systematic uncertainties of this model. We identify broad emission features in this spectral region, including emission due to ions of O, Ne, Mg, and other species, and we limit the intrinsic HeI 504 Angstrom photoelectric absorption edge opacity to $τ_{\rm HeI}<0.047$.
description: 15 pages, 9 figures, 4 tables. Accepted to the Astrophysical Journal
Impaired TFEB activation and mitophagy as a cause of PPP3/calcineurin inhibitor-induced pancreatic β-cell dysfunction
Creators: name: Park, Kihyoun
name: Sonn, Seong Keun
name: Seo, Seungwoon
name: Kim, Jinyoung
name: Hur, Kyu Yeon
name: Oh, Goo Taeg
name: Lee, Myung-Shik
Publisher: name: Taylor & Francis
Year: 2022
Subjects: subject: Biochemistry
subject: Medicine
subject: Cell Biology
subject: Genetics
subject: FOS: Biological sciences
subject: Neuroscience
subject: Physiology
subject: Pharmacology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Immunology
subject: FOS: Clinical medicine
subject: Cancer
subject: 60506 Virology

description: Macroautophagy/autophagy or mitophagy plays crucial roles in the maintenance of pancreatic β-cell function. PPP3/calcineurin can modulate the activity of TFEB, a master regulator of lysosomal biogenesis and autophagy gene expression, through dephosphorylation. We studied whether PPP3/calcineurin inhibitors can affect the mitophagy of pancreatic β-cells and pancreatic β-cell function employing FK506, an immunosuppressive drug against graft rejection. FK506 suppressed rotenone- or oligomycin+antimycin-A-induced mitophagy measured by Mito-Keima localization in acidic lysosomes or RFP-LC3 puncta colocalized with TOMM20 in INS-1 insulinoma cells. FK506 diminished nuclear translocation of TFEB after treatment with rotenone or oligomycin+antimycin A. Forced TFEB nuclear translocation by a constitutively active TFEB mutant transfection restored impaired mitophagy by FK506, suggesting the role of decreased TFEB nuclear translocation in FK506-mediated mitophagy impairment. Probably due to reduced mitophagy, recovery of mitochondrial potential or quenching of mitochondrial ROS after removal of rotenone or oligomycin+antimycin A was delayed by FK506. Mitochondrial oxygen consumption was reduced by FK506, indicating reduced mitochondrial function by FK506. Likely due to mitochondrial dysfunction, insulin release from INS-1 cells was reduced by FK506 in vitro. FK506 treatment also reduced insulin release and impaired glucose tolerance in vivo, which was associated with decreased mitophagy and mitochondrial COX activity in pancreatic islets. FK506-induced mitochondrial dysfunction and glucose intolerance were ameliorated by an autophagy enhancer activating TFEB. These results suggest that diminished mitophagy and consequent mitochondrial dysfunction of pancreatic β-cells contribute to FK506-induced β-cell dysfunction or glucose intolerance, and autophagy enhancement could be a therapeutic modality against post-transplantation diabetes mellitus caused by PPP3/calcineurin inhibitors.
Solar-Powered Housing for Emergency/Disaster Relief
Creators: name: Brandhorst, H.W.
name: Rodiek, J.A.
Publisher: name: WIP-Munich
Year: 2009
Subjects: PV Systems
Off-grid Applications and Rural Electrification

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 4306-4310
description: Hurricanes “Katrina” and “Ivan” exposed critical weakness in energy supply in the U.S. disaster
response system. This paper will discuss the concept of solar-powered modular housing for nation-wide disaster
relief. Auburn University has performed a design study that demonstrates feasibility of the concept. Now the plan is
to build two 398 ft2 “Katrina Cottages”, equip them with solar hot water heating, 2 kW of solar electric panels, and
a battery storage system to demonstrate housing for disaster responders and refugees. These units would be
inhabited, installed at two locations in Alabama, and have a smart control system that maximizes energy use with
minimal wasted energy and be monitored for one year. Combined with federal and state tax credits, the units will
demonstrate a viable business. This paper will discuss energy payback time, stand-alone operation, system
effectiveness and economic viability. Performance projections and lifetime financial analysis will also be presented.
Collection of Solar Energy at High Altitude
Creators: name: Redi, S.
name: Aglietti, G.S.
name: Tatnall, A.R.
name: Markvart, T.
Publisher: name: WIP-Munich
Year: 2009
Subjects: PV Systems
Off-grid Applications and Rural Electrification

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 4311-4317
description: This paper presents the preliminary concept evaluation of an innovative power generator based on
photovoltaic and lighter than air technologies. The generator consists of a helium filled platform tethered to the
ground that would be used to locate a photovoltaic array at high altitude in order to overcome the problems related to
the cloud coverage that in many northern countries hinders the extensive exploitation of the solar energy. First of all,
the potential of this technology is evaluated in terms of the solar energy that can be collected at high altitude. The
system is then described, focusing on the capability of the different components, and providing an overview of the
parameters involved in the design. A simplified model is then introduced to assess different technical solutions and
compare their performance. The results obtained demonstrate the advantage that this concept could bring in those
areas where the solar resource is scarce due to the bad weather conditions. Finally the following steps of the research,
which will lead to the detailed design and cost estimation of the system, are described and discussed.
The experience of Hamad General Hospital collaborative anticoagulation clinic in Qatar during the COVID-19 pandemic
Creators: name: Abdallah, Ibtihal
name: Eltahir, Asma
name: Fernyhough, Liam
name: El-Bardissy, Ahmed
name: Ahmed, Rana
name: Abdulgelil, Mohammed
name: Elgaily, Dina
name: Mohammed, AbdulMoqeeth
name: Jassim, Ameena
name: Barakat, Loluwa
name: Al-Ansari, Mazen
name: Javed, Mehak
name: Alkhawaja, Raja
name: Elzouki, Abdel-nasser
Publisher: name: Manara - Qatar Research Repository
Year: 2022
Subjects: Cardiovascular medicine and haematology
Public health

description: Hamad General Hospital Anticoagulation Clinic is one of the largest collaborative-practice clinics of its type in Qatar. The patients being followed at this clinic are typically complex and vulnerable. During the coronavirus disease 2019 pandemic, measures were implemented at the clinic to minimize the exposure of patients and healthcare providers to the acute respiratory syndrome coronavirus-2 and to promote social distancing. These measures included extending INR-recall period, transitioning to direct oral anticoagulant drugs whenever feasible, home visits to elderly and immunocompromised patients for INR testing, establishing an anticoagulation hotline, and relocation of warfarin dispensing from the main pharmacy to the anticoagulation clinic. In addition, the clinic shifted its multidisciplinary team meetings onto an online platform using Microsoft Teams. Telehealth consultations were extensively utilized to closely follow up with the patients and ensure that anticoagulation efficacy and safety remained optimal. The aim of this paper is to share our experience and describe the measures adopted by the clinic as part of the Hamad Medical Corporation response to the emerging situation.Other Information Published in: Journal of Thrombosis and Thrombolysis
 License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s11239-020-02276-4