Search results for: net atomic charge
1392 Water Vapor Oxidization of NiO for a Hole Transport Layer in All Inorganic QD-LED
Authors: Jaeun Park, Daekyoung Kim, Ho Kyoon Chung, Heeyeop Chae
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Quantum dots light-emitting diodes (QD-LEDs) have been considered as the next generation display and lighting devices due to their excellent color purity, photo-stability solution process possibility and good device stability. Currently typical quantum dot light emitting diodes contain organic layers such as PEDOT:PSS and PVK for charge transport layers. To make quantum dot light emitting diodes (QD-LED) more stable, it is required to replace those acidic and relatively unstable organic charge transport layers with inorganic materials. Therefore all inorganic and solution processed quantum dot light emitting diodes can potentially be a solution to stable and cost-effective display devices. We studied solution processed NiO films to replace organic charge transport layers that are required for stable all-inorganic based light emitting diodes. The transition metal oxides can be made by various vacuum and solution processes, but the solution processes are considered more cost-effective than vacuum processes. In this work we investigated solution processed NiOx for a hole transport layer (HTL). NiOx, has valence band energy levels of 5.3eV and they are easy to make sol-gel solutions. Water vapor oxidation process was developed and applied to solution processed all-inorganic QD-LED. Turn-on voltage, luminance and current efficiency of QD in this work were 5V, 1800Cd/m2 and 0.5Cd/A, respectively.Keywords: QD-LED, metal oxide solution, NiO, all-inorganic QD-LED device
Procedia PDF Downloads 7491391 Mn3O4 anchored Broccoli-Flower like Nickel Manganese Selenide Composite for Ultra-efficient Solid-State Hybrid Supercapacitors with Extended Durability
Authors: Siddhant Srivastav, Shilpa Singh, Sumanta Kumar Meher
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Innovative renewable energy sources for energy storage/conversion is the demand of the current scenario in electrochemical machinery. In this context, choosing suitable organic precipitants for tuning the crystal characteristics and microstructures is a challenge. On the same note, herein we report broccoli flower-like porous Mn3O4/NiSe2−MnSe2 composite synthesized using a simple two step hydrothermal synthesis procedure assisted by sluggish precipitating agent and an effective cappant followed by intermediated anion exchange. The as-synthesized material was exposed to physical and chemical measurements depicting poly-crystallinity, stronger bonding and broccoli flower-like porous arrangement. The material was assessed electrochemically by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) measurements. The Electrochemical studies reveal redox behavior, supercapacitive charge-discharge shape and extremely low charge transfer resistance. Further, the fabricated Mn3O4/NiSe2−MnSe2 composite based solid-state hybrid supercapacitor (Mn3O4/NiSe2−MnSe2 ||N-rGO) delivers excellent rate specific capacity, very low internal resistance, with energy density (~34 W h kg–1) of a typical rechargeable battery and power density (11995 W kg–1) of an ultra-supercapacitor. Consequently, it can be a favorable contender for supercapacitor applications for high performance energy storage utilizations. A definitive exhibition of the supercapacitor device is credited to electrolyte-ion buffering reservior alike behavior of broccoli flower like Mn3O4/NiSe2−MnSe2, enhanced by upgraded electronic and ionic conductivities of N- doped rGO (negative electrode) and PVA/KOH gel (electrolyte separator), respectivelyKeywords: electrolyte-ion buffering reservoir, intermediated-anion exchange, solid-state hybrid supercapacitor, supercapacitive charge-dischargesupercapacitive charge-discharge
Procedia PDF Downloads 731390 Effect of Retained Austenite Stability in Corrosion Mechanism of Dual Phase High Carbon Steel
Authors: W. Handoko, F. Pahlevani, V. Sahajwalla
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Dual-phase high carbon steels (DHCS) are commonly known for their improved strength, hardness, and abrasive resistance properties due to co-presence of retained austenite and martensite at the same time. Retained austenite is a meta-stable phase at room temperature, and stability of this phase governs the response of DHCS at different conditions. This research paper studies the effect of RA stability on corrosion behaviour of high carbon steels after they have been immersed into 1.0 M NaCl solution for various times. For this purpose, two different steels with different RA stabilities have been investigated. The surface morphology of the samples before and after corrosion attack was observed by secondary electron microscopy (SEM) and atomic force microscopy (AFM), along with the weight loss and Vickers hardness analysis. Microstructural investigations proved the preferential attack to retained austenite phase during corrosion. Hence, increase in the stability of retained austenite in dual-phase steels led to decreasing the weight loss rate.Keywords: high carbon steel, austenite stability, atomic force microscopy, corrosion
Procedia PDF Downloads 2101389 Study of Ambient Air Quality on Building's Roof of Dhaka City
Authors: Koninika Tanzim
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The gaseous pollutants, SO2, NO2, CO and O3 affect the environment of Dhaka City. These pollutants are mainly released from stationary sources, like, fossil-fueled, power plants, industrial units and brickfields around the city. Suspended particulate matters including PM10 and PM2.5 are also contributing to air pollution in Dhaka City. SO2, NO2 and O3 are determined by using UV and visible spectrophotometry. The sensor type devised has been used for the determination of CO in ambient air. Lead in the suspended particulate matter was determined by using atomic absorption spectrometry. The samples were collected at ground level and on the roof of a seven-storied building. For all the criteria pollutants, the concentration at the roof was found to the lower than that at the ground level. The average concentration of PM10 and PM2.5 were found to the 241.5 and 81.1 mg/m3 at the ground level. On the roof of a 7 storied building was however 49.99 mg/m3 and 25.88 mg/m3 for PM10 and PM2.5 respectively. The concentration of Pb varied from 0.011 to 0.04 mg/m3 at the ground level. The values for Pb at the roof level were significantly lower. The values for SO2, NO2, CO and O3 were found to be higher than the USEPA values.Keywords: gaseous air pollutant, PM, lead, gravimetry, spectrophotometry, atomic absorption, ambient air quality
Procedia PDF Downloads 4161388 The MoEDAL-MAPP* Experiment - Expanding the Discovery Horizon of the Large Hadron Collider
Authors: James Pinfold
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The MoEDAL (Monopole and Exotics Detector at the LHC) experiment deployed at IP8 on the Large Hadron Collider ring was the first dedicated search experiment to take data at the Large Hadron Collider (LHC) in 2010. It was designed to search for Highly Ionizing Particle (HIP) avatars of new physics such as magnetic monopoles, dyons, Q-balls, multiply charged particles, massive, slowly moving charged particles and long-lived massive charge SUSY particles. We shall report on our search at LHC’s Run-2 for Magnetic monopoles and dyons produced in p-p and photon-fusion. In more detail, we will report our most recent result in this arena: the search for magnetic monopoles via the Schwinger Mechanism in Pb-Pb collisions. The MoEDAL detector, originally the first dedicated search detector at the LHC, is being reinstalled for LHC’s Run-3 to continue the search for electrically and magnetically charged HIPs with enhanced instantaneous luminosity, detector efficiency and a factor of ten lower thresholds for HIPs. As part of this effort, we will search for massive l long-lived, singly and multiply charged particles from various scenarios for which MoEDAL has a competitive sensitivity. An upgrade to MoEDAL, the MoEDAL Apparatus for Penetrating Particles (MAPP), is now the LHC’s newest detector. The MAPP detector, positioned in UA83, expands the physics reach of MoEDAL to include sensitivity to feebly-charged particles with charge, or effective charge, as low as 10-3 e (where e is the electron charge). Also, In conjunction with MoEDAL’s trapping detector, the MAPP detector gives us a unique sensitivity to extremely long-lived charged particles. MAPP also has some sensitivity to long-lived neutral particles. The addition of an Outrigger detector for MAPP-1 to increase its acceptance for more massive milli-charged particles is currently in the Technical Proposal stage. Additionally, we will briefly report on the plans for the MAPP-2 upgrade to the MoEDAL-MAPP experiment for the High Luminosity LHC (HL-LHC). This experiment phase is designed to maximize MoEDAL-MAPP’s sensitivity to very long-lived neutral messengers of physics beyond the Standard Model. We envisage this detector being deployed in the UGC1 gallery near IP8.Keywords: LHC, beyond the standard model, dedicated search experiment, highly ionizing particles, long-lived particles, milli-charged particles
Procedia PDF Downloads 681387 Effect of Atrial Flutter on Alcoholic Cardiomyopathy
Authors: Ibrahim Ahmed, Richard Amoateng, Akhil Jain, Mohamed Ahmed
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Alcoholic cardiomyopathy (ACM) is a type of acquired cardiomyopathy caused by chronic alcohol consumption. Frequently ACM is associated with arrhythmias such as atrial flutter. Our aim was to characterize the patient demographics and investigate the effect of atrial flutter (AF) on ACM. This was a retrospective cohort study using the Nationwide Inpatient Sample database to identify admissions in adults with principal and secondary diagnoses of alcoholic cardiomyopathy and atrial flutter from 2019. Multivariate linear and logistic regression models were adjusted for age, gender, race, household income, insurance status, Elixhauser comorbidity score, hospital location, bed size, and teaching status. The primary outcome was all-cause mortality, and secondary outcomes were the length of stay (LOS) and total charge in USD. There was a total of 21,855 admissions with alcoholic cardiomyopathy, of which 1,635 had atrial flutter (AF-ACM). Compared to Non-AF-ACM cohort, AF-ACM cohort had fewer females (4.89% vs 14.54%, p<0.001), were older (58.66 vs 56.13 years, p<0.001), fewer Native Americans (0.61% vs2.67%, p<0.01), had fewer smaller (19.27% vs 22.45%, p<0.01) & medium-sized hospitals (23.24% vs28.98%, p<0.01), but more large-sized hospitals (57.49% vs 48.57%, p<0.01), more Medicare (40.37% vs 34.08%, p<0.05) and fewer Medicaid insured (23.55% vs 33.70%, p=<0.001), fewer hypertension (10.7% vs 15.01%, p<0.05), and more obesity (24.77% vs 16.35%, p<0.001). Compared to Non-AF-ACM cohort, there was no difference in AF-ACM cohort mortality rate (6.13% vs 4.20%, p=0.0998), unadjusted mortality OR 1.49 (95% CI 0.92-2.40, p=0.102), adjusted mortality OR 1.36 (95% CI 0.83-2.24, p=0.221), but there was a difference in LOS 1.23 days (95% CI 0.34-2.13, p<0.01), total charge $28,860.30 (95% CI 11,883.96-45,836.60, p<0.01). In patients admitted with ACM, the presence of AF was not associated with a higher all-cause mortality rate or odds of all-cause mortality; however, it was associated with 1.23 days increase in LOS and a $28,860.30 increase in total hospitalization charge. Native Americans, older age and obesity were risk factors for the presence of AF in ACM.Keywords: alcoholic cardiomyopathy, atrial flutter, cardiomyopathy, arrhythmia
Procedia PDF Downloads 1121386 Evaluation of Elements Impurities in Drugs According to Pharmacopoeia by use FESEM-EDS Technique
Authors: Rafid Doulab
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Elemental Impurities in the Pharmaceuticals industryis are indispensable to ensure pharmaceuticalssafety for 24 elements. Although atomic absorption and inductively coupled plasma are used in the U.S Pharmacopeia and the European Pharmacopoeia, FESEM with energy dispersive spectrometers can be applied as an alternative analysis method for quantitative and qualitative results for a variety of elements without chemical pretreatment, unlike other techniques. This technique characterizes by shortest time, with more less contamination, no reagent consumption, and generation of minimal residue or waste, as well as sample preparations time limiting, with minimal analysis error. Simple dilution for powder or direct analysis for liquid, we analyzed the usefulness of EDS method in testing with field emission scanning electron microscopy (FESEM, SUPRA 55 Carl Zeiss Germany) with an X-ray energy dispersion (XFlash6l10 Bruker Germany). The samples analyzed directly without coating by applied 5µ of known concentrated diluted sample on carbon stub with accelerated voltage according to sample thickness, the result for this spot was in atomic percentage, and by Avogadro converted factor, the final result will be in microgram. Conclusion and recommendation: The conclusion of this study is application of FESEM-EDS in US pharmacopeia and ICH /Q3D guideline to reach a high-precision and accurate method in element impurities analysis of drugs or bulk materials to determine the permitted daily exposure PDE in liquid or solid specimens, and to obtain better results than other techniques, by the way it does not require complex methods or chemicals for digestion, which interfere with the final results with the possibility of to keep the sample at any time for re analysis. The recommendation is to use this technique in pharmacopeia as standard methods like inductively coupled plasma both ICP-AES, ICP-OES, and ICP-MS.Keywords: pharmacopoeia, FESEM-EDS, element impurities, atomic concentration
Procedia PDF Downloads 1151385 Modelling of Rate-Dependent Hysteresis of Polypyrrole Dual Sensing-Actuators for Precise Position Control
Authors: Johanna Schumacher, Toribio F. Otero, Victor H. Pascual
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Bending dual sensing-actuators based on electroactive polymers are faradaic motors meaning the consumed charge determines the actuator’s tip position. During actuation, consumed charges during oxidation and reduction result in different tip positions showing dynamic hysteresis effects with errors up to 25%. For a precise position control of these actuators, the characterization of the hysteresis effect due to irreversible reactions is crucial. Here, the investigation and modelling of dynamic hysteresis effects of polypyrrole-dodezylbenzenesulfonate (PPyDBS) actuators under ambient working conditions are presented. The hysteresis effect is studied for charge consumption at different frequencies and a rate-dependent hysteresis model is derived. The hysteresis model is implemented as closed loop system and is verified experimentally.Keywords: dual sensing-actuator, electroactive polymers, hysteresis, position control
Procedia PDF Downloads 3851384 Recent Progress in the Uncooled Mid-Infrared Lead Selenide Polycrystalline Photodetector
Authors: Hao Yang, Lei Chen, Ting Mei, Jianbang Zheng
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Currently, the uncooled PbSe photodetectors in the mid-infrared range (2-5μm) with sensitization technology extract more photoelectric response than traditional ones, and enable the room temperature (300K) photo-detection with high detectivity, which have attracted wide attentions in many fields. This technology generally contains the film fabrication with vapor phase deposition (VPD) and a sensitizing process with doping of oxygen and iodine. Many works presented in the recent years almost provide and high temperature activation method with oxygen/iodine vapor diffusion, which reveals that oxygen or iodine plays an important role in the sensitization of PbSe material. In this paper, we provide our latest experimental results and discussions in the stoichiometry of oxygen and iodine and its influence on the polycrystalline structure and photo-response. The experimental results revealed that crystal orientation was transformed from (200) to (420) by sensitization, and the responsivity of 5.42 A/W was gained by the optimal stoichiometry of oxygen and iodine with molecular density of I2 of ~1.51×1012 mm-3 and oxygen pressure of ~1Mpa. We verified that I2 plays a role in transporting oxygen into the lattice of crystal, which is actually not its major role. It is revealed that samples sensitized with iodine transform atomic proportion of Pb from 34.5% to 25.0% compared with samples without iodine from XPS data, which result in the proportion of about 1:1 between Pb and Se atoms by sublimation of PbI2 during sensitization process, and Pb/Se atomic proportion is controlled by I/O atomic proportion in the polycrystalline grains, which is very an important factor for improving responsivity of uncooled PbSe photodetector. Moreover, a novel sensitization and dopant activation method is proposed using oxygen ion implantation with low ion energy of < 500eV and beam current of ~120μA/cm2. These results may be helpful to understanding the sensitization mechanism of polycrystalline lead salt materials.Keywords: polycrystalline PbSe, sensitization, transport, stoichiometry
Procedia PDF Downloads 3471383 Implementation of a PDMS Microdevice for the Improved Purification of Circulating MicroRNAs
Authors: G. C. Santini, C. Potrich, L. Lunelli, L. Vanzetti, S. Marasso, M. Cocuzza, C. Pederzolli
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The relevance of circulating miRNAs as non-invasive biomarkers for several pathologies is nowadays undoubtedly clear, as they have been found to have both diagnostic and prognostic value able to add fundamental information to patients’ clinical picture. The availability of these data, however, relies on a time-consuming process spanning from the sample collection and processing to the data analysis. In light of this, strategies which are able to ease this procedure are in high demand and considerable effort have been made in developing Lab-on-a-chip (LOC) devices able to speed up and standardise the bench work. In this context, a very promising polydimethylsiloxane (PDMS)-based microdevice which integrates the processing of the biological sample, i.e. purification of extracellular miRNAs, and reverse transcription was previously developed in our lab. In this study, we aimed at the improvement of the miRNA extraction performances of this micro device by increasing the ability of its surface to absorb extracellular miRNAs from biological samples. For this purpose, we focused on the modulation of two properties of the material: roughness and charge. PDMS surface roughness was modulated by casting with several templates (terminated with silicon oxide coated by a thin anti-adhesion aluminum layer), followed by a panel of curing conditions. Atomic force microscopy (AFM) was employed to estimate changes at the nanometric scale. To introduce modifications in surface charge we functionalized PDMS with different mixes of positively charged 3-aminopropyltrimethoxysilanes (APTMS) and neutral poly(ethylene glycol) silane (PEG). The surface chemical composition was characterized by X-ray photoelectron spectroscopy (XPS) and the number of exposed primary amines was quantified with the reagent sulfosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate (s-SDTB). As our final end point, the adsorption rate of all these different conditions was assessed by fluorescence microscopy by incubating a synthetic fluorescently-labeled miRNA. Our preliminary analysis identified casting on thermally grown silicon oxide, followed by a curing step at 85°C for 1 hour, as the most efficient technique to obtain a PDMS surface roughness in the nanometric scaleable to trap miRNA. In addition, functionalisation with 0.1% APTMS and 0.9% PEG was found to be a necessary step to significantly increase the amount of microRNA adsorbed on the surface, therefore, available for further steps as on-chip reverse transcription. These findings show a substantial improvement in the extraction efficiency of our PDMS microdevice, ultimately leading to an important step forward in the development of an innovative, easy-to-use and integrated system for the direct purification of less abundant circulating microRNAs.Keywords: circulating miRNAs, diagnostics, Lab-on-a-chip, polydimethylsiloxane (PDMS)
Procedia PDF Downloads 3171382 Nanoparticle Based Green Inhibitor for Corrosion Protection of Zinc in Acidic Medium
Authors: Neha Parekh, Divya Ladha, Poonam Wadhwani, Nisha Shah
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Nano scaled materials have attracted tremendous interest as corrosion inhibitor due to their high surface area on the metal surfaces. It is well known that the zinc oxide nanoparticles have higher reactivity towards aqueous acidic solution. This work presents a new method to incorporate zinc oxide nanoparticles with white sesame seeds extract (nano-green inhibitor) for corrosion protection of zinc in acidic medium. The morphology of the zinc oxide nanoparticles was investigated by TEM and DLS. The corrosion inhibition efficiency of the green inhibitor and nano-green inhibitor was determined by Gravimetric and electrochemical impedance spectroscopy (EIS) methods. Gravimetric measurements suggested that nano-green inhibitor is more effective than green inhibitor. Furthermore, with the increasing temperature, inhibition efficiency increases for both the inhibitors. In addition, it was established the Temkin adsorption isotherm fits well with the experimental data for both the inhibitors. The effect of temperature and Temkin adsorption isotherm revealed Chemisorption mechanism occurring in the system. The activation energy (Ea) and other thermodynamic parameters for inhibition process were calculated. The data of EIS showed that the charge transfer controls the corrosion process. The surface morphology of zinc metal (specimen) in absence and presence of green inhibitor and nano-green inhibitor were performed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. The outcomes indicated a formation of a protective layer over zinc metal (specimen).Keywords: corrosion, green inhibitor, nanoparticles, zinc
Procedia PDF Downloads 4531381 The Charge Exchange and Mixture Formation Model in the ASz-62IR Radial Aircraft Engine
Authors: Pawel Magryta, Tytus Tulwin, Paweł Karpiński
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The ASz62IR engine is a radial aircraft engine with 9 cylinders. This object is produced by the Polish company WSK "PZL-KALISZ" S.A. This is engine is currently being developed by the above company and Lublin University of Technology. In order to provide an effective work of the technological development of this unit it was decided to made the simulation model. The model of ASz-62IR was developed with AVL BOOST software which is a tool dedicated to the one-dimensional modeling of internal combustion engines. This model can be used to calculate parameters of an air and fuel flow in an intake system including charging devices as well as combustion and exhaust flow to the environment. The main purpose of this model is the analysis of the charge exchange and mixture formation in this engine. For this purpose, the model consists of elements such: as air inlet, throttle system, compressor connector, charging compressor, inlet pipes and injectors, outlet pipes, fuel injection and model of fuel mixing and evaporation. The model of charge exchange and mixture formation was based on the model of mass flow rate in intake and exhaust pipes, and also on the calculation of gas properties values like gas constant or thermal capacity. This model was based on the equations to describe isentropic flow. The energy equation to describe flow under steady conditions was transformed into the mass flow equation. In the model the flow coefficient μσ was used, that varies with the stroke/valve opening and was determined in a steady flow state. The geometry of the inlet channels and other key components was mapped with reference to the technical documentation of the engine and empirical measurements of the structure elements. The volume of elements on the charge flow path between the air inlet and the exhaust outlet was measured by the CAD mapping of the structure. Taken from the technical documentation, the original characteristics of the compressor engine was entered into the model. Additionally, the model uses a general model for the transport of chemical compounds of the mixture. There are 7 compounds used, i.e. fuel, O2, N2, CO2, H2O, CO, H2. A gasoline fuel of a calorific value of 43.5 MJ/kg and an air mass fraction for stoichiometric mixture of 14.5 were used. Indirect injection into the intake manifold is used in this model. The model assumes the following simplifications: the mixture is homogenous at the beginning of combustion, accordingly, mixture stoichiometric coefficient A/F remains constant during combustion, combusted and non-combusted charges show identical pressures and temperatures although their compositions change. As a result of the simulation studies based on the model described above, the basic parameters of combustion process, charge exchange, mixture formation in cylinders were obtained. The AVL Boost software is very useful for the piston engine performance simulations. This work has been financed by the Polish National Centre for Research and Development, INNOLOT, under Grant Agreement No. INNOLOT/I/1/NCBR/2013.Keywords: aviation propulsion, AVL Boost, engine model, charge exchange, mixture formation
Procedia PDF Downloads 3351380 Electronic Device Robustness against Electrostatic Discharges
Authors: Clara Oliver, Oibar Martinez
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This paper is intended to reveal the severity of electrostatic discharge (ESD) effects in electronic and optoelectronic devices by performing sensitivity tests based on Human Body Model (HBM) standard. We explain here the HBM standard in detail together with the typical failure modes associated with electrostatic discharges. In addition, a prototype of electrostatic charge generator has been designed, fabricated, and verified to stress electronic devices, which features a compact high voltage source. This prototype is inexpensive and enables one to do a battery of pre-compliance tests aimed at detecting unexpected weaknesses to static discharges at the component level. Some tests with different devices were performed to illustrate the behavior of the proposed generator. A set of discharges was applied according to the HBM standard to commercially available bipolar transistors, complementary metal-oxide-semiconductor transistors and light emitting diodes. It is observed that high current and voltage ratings in electronic devices not necessarily provide a guarantee that the device will withstand high levels of electrostatic discharges. We have also compared the result obtained by performing the sensitivity tests based on HBM with a real discharge generated by a human. For this purpose, the charge accumulated in the person is monitored, and a direct discharge against the devices is generated by touching them. Every test has been performed under controlled relative humidity conditions. It is believed that this paper can be of interest for research teams involved in the development of electronic and optoelectronic devices which need to verify the reliability of their devices in terms of robustness to electrostatic discharges.Keywords: human body model, electrostatic discharge, sensitivity tests, static charge monitoring
Procedia PDF Downloads 1491379 Deposition Rates and Annealing Effects on the Growth of Nb Thin Film on Cu Substrate: Molecular Dynamic Simulation
Authors: Lablali Mohammed, Mes-Adi Hassan, Mazroui M’Hammed
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To tackle the complexity of grasping atomic-scale structures and unraveling the factors affecting the development of thin films. In our work, we perform the deposition of Nb atoms on Cu substrates using the molecular dynamics simulation combined with the embedded atom method to describe the interaction between different atoms. We investigated the impact of varying deposition rates and thermal annealing processes on the microstructural, morphological, and mechanical characteristics of the deposited Nb film. Our findings reveal that Nb atom growth on the Cu substrate occurs in island mode, accompanied by the presence of nucleation phenomena during growth. On the other hand, mixing behavior was observed at the interface between the film and the substrate, where Nb penetration is initially limited to the first Cu layer, whereas Cu atoms diffuse until reaching the third layer in the Nb film. Furthermore, Nb exhibits a BCC structure, with a significant concentration observed at a rate of 5 atoms/ps, and annealing further amplifies these percentages. Deposition at different rates leads to distinct levels of compressive normal and biaxial stress.Keywords: molecular dynamics, Nb thin film, structure and morphology, atomic penetration
Procedia PDF Downloads 301378 Do Industry Expert Audit Engagement Partners Earn Fee Premiums? Evidence from Labor Usage and the Hourly Charge Rate
Authors: Gil Bae, Seung Uk Choi, Jae Eun Lee, Joon Hwa Rho
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Using proprietary engagement partner identity information for the Big 4 audit firms in Korea over the 2001-2011 period, we find that expert engagement partners obtain significantly higher total compensation than do non-expert partners. Importantly, we also find that expert partners increase the number of audit hours compared to their non-expert counterparts. The hourly billing rate, calculated as total fees divided by total audit hours, of expert partners is not higher than that of non-expert partners, indicating that there is no expert partner premium reflected in the hourly rate. This finding suggests that the increase in total audit fees is attributable mainly to the increase in the quantity of audit hours that expert partners work, not from the higher fee per hour. The results are not attributable to auditor selection bias.Keywords: industry expert partners, expert premiums, audit hours, hourly charge rate
Procedia PDF Downloads 3031377 Development of Agomelatine Loaded Proliposomal Powders for Improved Intestinal Permeation: Effect of Surface Charge
Authors: Rajasekhar Reddy Poonuru, Anusha Parnem
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Purpose: To formulate proliposome powder of agomelatine, an antipsychotic drug, and to evaluate physicochemical, in vitro characters and effect of surface charge on ex vivo intestinal permeation. Methods: Film deposition technique was employed to develop proliposomal powders of agomelatin with varying molar ratios of lipid Hydro Soy PC L-α-phosphatidylcholine (HSPC) and cholesterol with fixed sum of drug. With the aim to derive free flowing and stable proliposome powder, fluid retention potential of various carriers was examined. Liposome formation and number of vesicles formed for per mm3 up on hydration, vesicle size, and entrapment efficiency was assessed to deduce an optimized formulation. Sodium cholate added to optimized formulation to induce surface charge on formed vesicles. Solid-state characterization (FTIR, DSC, and XRD) was performed with the intention to assess native crystalline and chemical behavior of drug. The in vitro dissolution test of optimized formulation along with pure drug was evaluated to estimate dissolution efficiency (DE) and relative dissolution rate (RDR). Effective permeability co-efficient (Peff(rat)) in rat and enhancement ratio (ER) of drug from formulation and pure drug dispersion were calculated from ex vivo permeation studies in rat ileum. Results: Proliposomal powder formulated with equimolar ratio of HSPC and cholesterol ensued in higher no. of vesicles (3.95) with 90% drug entrapment up on hydration. Neusilin UFL2 was elected as carrier because of its high fluid retention potential (4.5) and good flow properties. Proliposome powder exhibited augmentation in DE (60.3 ±3.34) and RDR (21.2±01.02) of agomelation over pure drug. Solid state characterization studies demonstrated the transformation of native crystalline form of drug to amorphous and/or molecular state, which was in correlation with results obtained from in vitro dissolution test. The elevated Peff(rat) of 46.5×10-4 cm/sec and ER of 2.65 of drug from charge induced proliposome formulation with respect to pure drug dispersion was assessed from ex vivo intestinal permeation studies executed in ileum of wistar rats. Conclusion: Improved physicochemical characters and ex vivo intestinal permeation of drug from charge induced proliposome powder with Neusilin UFL2 unravels the potentiality of this system in enhancing oral delivery of agomelatin.Keywords: agomelatin, proliposome, sodium cholate, neusilin
Procedia PDF Downloads 1351376 Corrosion Control of Carbon Steel Surface by Phosphonic Acid Nano-Layers
Authors: T. Abohalkuma, J. Telegdi
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Preparation, characterization, and application of self-assembled monolayers (SAM) formed by fluorophosphonic and undecenyl phosphonic acids on carbon steel surfaces as anticorrosive nanocoatings were demonstrated. The anticorrosive efficacy of these SAM layers was followed by atomic force microscopy, as the change in the surface morphology caused by layer deposition and corrosion processes was monitored. The corrosion process was determined by electrochemical potentiodynamic polarization, whereas the surface wettability of the carbon steel samples was tested with the use of static and dynamic contact angle measurements. Results showed that both chemicals produced good protection against corrosion as they performed as anodic inhibitors, especially with increasing the time of layer formation, which results in a more compact molecular film. According to the atomic force microscope (AFM) images, the fluoro-phosphonic acid self-assembled molecular layer can control the general as well as the pitting corrosion, but the SAM layers of the undecenyl-phosphonic acid cannot inhibit the pitting corrosion. The AFM and the contact angle measurements confirmed the results achieved by electrochemical measurements.Keywords: nanolayers, corrosion, phosphonic acids, coatings
Procedia PDF Downloads 1701375 Absorption and Carrier Transport Properties of Doped Hematite
Authors: Adebisi Moruf Ademola
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Hematite (Fe2O3),commonly known as ‘rust’ which usually surfaced on metal when exposed to some climatic materials. This emerges as a promising candidate for photoelectrochemical (PEC) water splitting due to its favorable physiochemical properties of the narrow band gap (2.1–2.2 eV), chemical stability, nontoxicity, abundance, and low cost. However, inherent limitations such as short hole diffusion length (2–4 nm), high charge recombination rate, and slow oxygen evolution reaction kinetics inhibit the PEC performances of a-Fe2O3 photoanodes. As such, given the narrow bandgap enabling excellent optical absorption, increased charge carrier density and accelerated surface oxidation reaction kinetics become the key points for improved photoelectrochemical performances for a-Fe2O3 photoanodes and metal ion doping as an effective way to promote charge transfer by increasing donor density and improving the electronic conductivity of a-Fe2O3. Hematite attracts enormous efforts with a number of metal ions (Ti, Zr, Sn, Pt ,etc.) as dopants. A facile deposition-annealing process showed greatly enhanced PEC performance due to the increased donor density and reduced electron-hole recombination at the time scale beyond a few picoseconds. Zr doping was also found to enhance the PEC performance of a-Fe2O3 nanorod arrays by reducing the rate of electron-hole recombination. Slow water oxidation reaction kinetics, another main factor limiting the PEC water splitting efficiency of aFe2O3 as photoanodes, was previously found to be effectively improved by surface treatment.Keywords: deposition-annealing, hematite, metal ion doping, nanorod
Procedia PDF Downloads 2191374 Internet of Things Based Battery Management System
Authors: Pakhil Singh, Rahul Singh, Mohammad Saad Alam, Yasser Rafat
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The battery management system is an essential package/system which ensures optimum performance and safety of a battery by monitoring the key essential parameters of the battery like the voltage, current, temperature, state of charge, state of health during charging and discharging. This can be accomplished using outputs of various sensors employed to serve the purpose. The increasing demand for electricity generation from renewable energy sources requires proper storage and hence a proper monitoring system as well. A battery management system is required in wide applications ranging from renewable energy storage systems, off-grid solar PV applications to electric vehicles. The aim of this paper is to study the parameters used in monitoring various battery operating conditions and proposes the usage of the internet of things (IoT) to implement a reliable battery management system.Keywords: electric vehicles, internet of things, sensors, state of charge, state of health
Procedia PDF Downloads 1961373 Characterization of Carbazole-Based Host Material for Highly Efficient Thermally Activated Delayed Fluorescence Emitter
Authors: Malek Mahmoudi, Jonas Keruckas, Dmytro Volyniuk, Jurate Simokaitiene, Juozas V. Grazulevicius
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Host materials have been discovered as one of the most appealing methods for harvesting triplet states in organic materials for application in organic light-emitting diodes (OLEDs). The ideal host-guest system for emission in thermally delayed fluorescence OLEDs with 20% guest concentration for efficient energy transfer has been demonstrated in the present investigation. In this work, 3,3'-bis[9-(4-fluorophenyl) carbazole] (bFPC) has been used as the host, which induces balanced charge carrier transport for high-efficiency OLEDs.For providing a complete characterization of the synthesized compound, photophysical, photoelectrical, charge-transporting, and electrochemical properties of the compound have been examined. Excited-state lifetimes and singlet-triplet energy gaps were measured for characterization of photophysical properties, while thermogravimetric analysis, as well as differential scanning calorimetry measurements, were performed for probing of electrochemical and thermal properties of the compound. The electrochemical properties of this compound were investigated by cyclic voltammetry (CV) method, and ionization potential (IPCV) value of 5.68 eV was observed. UV–Vis absorption and photoluminescence spectrum of a solution of the compound in toluene (10-5 M) showed maxima at 302 and 405 nm, respectively. Photoelectron emission spectrometry was used for the characterization of charge-injection properties of the studied compound in solid. The ionization potential of this material was found to be 5.78 eV, and time-of-flight measurement was used for testing charge-transporting properties and hole mobility estimated using this technique in a vacuum-deposited layer reached 4×10-4 cm2 V-1s-1. Since the compound with high charge mobilities was tested as a host in an organic light-emitting diode. The device was fabricated by successive deposition onto a pre-cleaned indium tin oxide (ITO) coated glass substrate under a vacuum of 10-6 Torr and consisting of an indium-tin-oxide anode, hole injection and transporting layer(MoO3, NPB), emitting layer with bFPC as a host and 4CzIPN (2,4,5,6-tetra(9-carbazolyl)isophthalonitrile) which is a new highly efficient green thermally activated delayed fluorescence (TADF) material as an emitter, an electron transporting layer(TPBi) and lithium fluoride layer topped with aluminum layer as a cathode exhibited the highest maximum current efficiency and power efficiency of 33.9 cd/A and 23.5 lm/W, respectively and the electroluminescence spectrum showed only a peak at 512nm. Furthermore, the new bicarbazole-based compound was tested as a host in thermally activated delayed fluorescence organic light-emitting diodes are reaching luminance of 25300 cd m-2 and external quantum efficiency of 10.1%. Interestingly, the turn-on voltage was low enough (3.8 V), and such a device can be used for highly efficient light sources.Keywords: thermally-activated delayed fluorescence, host material, ionization energy, charge mobility, electroluminescence
Procedia PDF Downloads 1391372 Study of Heat Transfer through the Ground and its Accumulation Properties to Increase the Energy Efficiency of Underground Buildings
Authors: Sandeep Bandarwadkar, Tadas Zdankus
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To maintain a comfortable indoor temperature for its residents in the colder season, heating a building is necessary. Due to the expansion in the construction sectors, the consumption of heating energy is increasing. According to Eurostat data, in the European Union, the share of energy consumption of heating energy for space and cooling in residential buildings was around 63% in 2019. These figures indicate that heating energy still accounts for a significant portion of total energy consumption in Europe. Innovation is crucial to reduce energy consumption in buildings and achieve greater energy efficiency and sustainability. It can bring about new solutions that are smarter and more natural energy generation to reduce greenhouse gas emissions. The ground can serve as an effective and sustainable heat accumulator for heating and cooling. The temperature of the ground is higher than that of the ambient air in the colder period and lower in the warmer period. The building deep in the soil could use less thermal energy compared to the above-ground buildings that provide the same amount of thermal comfort. The temperature difference between the soil and the air inside the building decreases as the temperature of the soil increases. In progress, this process generates the condition that acts against heat loss. However, heat dissipates further to the consecutive layers and reaches thermal equilibrium. The charging of the ground by heat and its dissipation through the adjacent soil layers was investigated experimentally. The results of this research showed that 9% of the energy savings in partially underground buildings and 44.4% in completely underground buildings were derived from heating the space. Heat loss to the ground is treated as a charge of the soil by thermal energy. The dependence of the intensity of the charge on time was analysed and presented.Keywords: heat transfer, accumulation of heat, underground building, soil charge
Procedia PDF Downloads 701371 Some Trace and Toxic Metal Content of Crude Ethanol Leaf Extract of Globimetula Oreophila (Hook. F) Danser Azadirachta Indica Using Atomic Absorption Spectroscopy
Authors: Dauda G., Bila Ha Sani Y. M., Magaji M. G., Musa A. M., Hassan H. S.
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Introduction: Globimetula oreophila is a parasitic plant with a known therapeutic value that is widely used in the treatment of various ailments, including malaria, hypertension, cancer, diabetes, epilepsy and as a diuretic agent. Objectives: The present study is aimed at analyzing and documenting the level of trace and toxic metals in the crude ethanol leaf extract of G. oreophila. Methods: After collection and authentication, the leaves were air-dried, mashed into powder, weighed and extracted using aqueous ethanol (70%). The crude extract (0.5g) was digested with HNO₃: HCl (3:1); then heated to 2000C and analyzed for its metal content by atomic absorption spectroscopy (AAS). Results: Fe had the highest concentration (32.73mg/kg), while Pb was not detected. The concentrations of Co, Cu, Ni, Zn and Cd detected were 5.97, 10.8, 8.01 and 0.9mg/kg, respectively. The concentration of Cd, Fe and Ni were above the permissible limit of FAO/WHO. Conclusion: The results also show that the analyzed plant is a beneficial source of appropriate and essential trace metals. However, the leaf of G. oreophila in the present study was probably unsafe for long-term use because of the level of Fe, Ni, and Cd concentration.Keywords: Globimetula oreophila, minerals, trace element, crude extract
Procedia PDF Downloads 1511370 The Effects of Stoke's Drag, Electrostatic Force and Charge on Penetration of Nanoparticles through N95 Respirators
Authors: Jacob Schwartz, Maxim Durach, Aniruddha Mitra, Abbas Rashidi, Glen Sage, Atin Adhikari
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NIOSH (National Institute for Occupational Safety and Health) approved N95 respirators are commonly used by workers in construction sites where there is a large amount of dust being produced from sawing, grinding, blasting, welding, etc., both electrostatically charged and not. A significant portion of airborne particles in construction sites could be nanoparticles created beside coarse particles. The penetration of the particles through the masks may differ depending on the size and charge of the individual particle. In field experiments relevant to this current study, we found that nanoparticles of medium size ranges are penetrating more frequently than nanoparticles of smaller and larger sizes. For example, penetration percentages of nanoparticles of 11.5 – 27.4 nm into a sealed N95 respirator on a manikin head ranged from 0.59 to 6.59%, whereas nanoparticles of 36.5 – 86.6 nm ranged from 7.34 to 16.04%. The possible causes behind this increased penetration of mid-size nanoparticles through mask filters are not yet explored. The objective of this study is to identify causes behind this unusual behavior of mid-size nanoparticles. We have considered such physical factors as Boltzmann distribution of the particles in thermal equilibrium with the air, kinetic energy of the particles at impact on the mask, Stoke’s drag force, and electrostatic forces in the mask stopping the particles. When the particles collide with the mask, only the particles that have enough kinetic energy to overcome the energy loss due to the electrostatic forces and the Stokes’ drag in the mask can pass through the mask. To understand this process, the following assumptions were made: (1) the effect of Stoke’s drag depends on the particles’ velocity at entry into the mask; (2) the electrostatic force is proportional to the charge on the particles, which in turn is proportional to the surface area of the particles; (3) the general dependence on electrostatic charge and thickness means that for stronger electrostatic resistance in the masks and thicker the masks’ fiber layers the penetration of particles is reduced, which is a sensible conclusion. In sampling situations where one mask was soaked in alcohol eliminating electrostatic interaction the penetration was much larger in the mid-range than the same mask with electrostatic interaction. The smaller nanoparticles showed almost zero penetration most likely because of the small kinetic energy, while the larger sized nanoparticles showed almost negligible penetration most likely due to the interaction of the particle with its own drag force. If there is no electrostatic force the fraction for larger particles grows. But if the electrostatic force is added the fraction for larger particles goes down, so diminished penetration for larger particles should be due to increased electrostatic repulsion, may be due to increased surface area and therefore larger charge on average. We have also explored the effect of ambient temperature on nanoparticle penetrations and determined that the dependence of the penetration of particles on the temperature is weak in the range of temperatures in the measurements 37-42°C, since the factor changes in the range from 3.17 10-3K-1 to 3.22 10-3K-1.Keywords: respiratory protection, industrial hygiene, aerosol, electrostatic force
Procedia PDF Downloads 1941369 Assessment of Zinc Content in Nuts by Atomic Absorption Spectrometry Method
Authors: Katarzyna Socha, Konrad Mielcarek, Grzegorz Kangowski, Renata Markiewicz-Zukowska, Anna Puscion-Jakubik, Jolanta Soroczynska, Maria H. Borawska
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Nuts have high nutritional value. They are a good source of polyunsaturated fatty acids, dietary fiber, vitamins (B₁, B₆, E, K) and minerals: magnesium, selenium, zinc (Zn). Zn is an essential element for proper functioning and development of human organism. Due to antioxidant and anti-inflammatory properties, Zn has an influence on immunological and central nervous system. It also affects proper functioning of reproductive organs and has beneficial impact on the condition of skin, hair, and nails. The objective of this study was estimation of Zn content in edible nuts. The research material consisted of 10 types of nuts, 12 samples of each type: almonds, brazil nuts, cashews, hazelnuts, macadamia nuts, peanuts, pecans, pine nuts, pistachios, and walnuts. The samples of nuts were digested in concentrated nitric acid using microwave mineralizer (Berghof, Germany). The concentration of Zn was determined by flame atomic absorption spectrometry method with Zeeman background correction (Hitachi, Japan). The accuracy of the method was verified on certified reference material: Simulated Diet D. The statistical analysis was performed using Statistica v. 13.0 software. For comparison between the groups, t-Student test was used. The highest content of Zn was shown in pine nuts and cashews: 78.57 ± 21.9, 70.02 ± 10,2 mg/kg, respectively, significantly higher than in other types of nuts. The lowest content of Zn was found in macadamia nuts: 16.25 ± 4.1 mg/kg. The consumption of a standard 42-gram portion of almonds, brazil nuts, cashews, peanuts, pecans, and pine nuts covers the daily requirement for Zn above 15% of recommended daily allowances (RDA) for women, while in the case of men consumption all of the above types of nuts, except peanuts. Selected types of nuts can be a good source of Zn in the diet.Keywords: atomic absorption spectrometry, microelement, nuts, zinc
Procedia PDF Downloads 1921368 Analog Voltage Inverter Drive for Capacitive Load with Adaptive Gain Control
Authors: Sun-Ki Hong, Yong-Ho Cho, Ki-Seok Kim, Tae-Sam Kang
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Piezoelectric actuator is treated as RC load when it is modeled electrically. For some piezoelectric actuator applications, arbitrary voltage is required to actuate. Especially for unidirectional arbitrary voltage driving like as sine wave, some special inverter with circuit that can charge and discharge the capacitive energy can be used. In this case, the difference between power supply level and the object voltage level for RC load is varied. Because the control gain is constant, the controlled output is not uniform according to the voltage difference. In this paper, for charge and discharge circuit for unidirectional arbitrary voltage driving for piezoelectric actuator, the controller gain is controlled according to the voltage difference. With the proposed simple idea, the load voltage can have controlled smoothly although the voltage difference is varied. The appropriateness is proved from the simulation of the proposed circuit.Keywords: analog voltage inverter, capacitive load, gain control, dc-dc converter, piezoelectric, voltage waveform
Procedia PDF Downloads 6541367 Heat Transfer Phenomena Identification of a Non-Active Floor in a Stack-Ventilated Building in Summertime: Empirical Study
Authors: Miguel Chen Austin, Denis Bruneau, Alain Sempey, Laurent Mora, Alain Sommier
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An experimental study in a Plus Energy House (PEH) prototype was conducted in August 2016. It aimed to highlight the energy charge and discharge of a concrete-slab floor submitted to the day-night-cycles heat exchanges in the southwestern part of France and to identify the heat transfer phenomena that take place in both processes: charge and discharge. The main features of this PEH, significant to this study, are the following: (i) a non-active slab covering the major part of the entire floor surface of the house, which include a concrete layer 68 mm thick as upper layer; (ii) solar window shades located on the north and south facades along with a large eave facing south, (iii) large double-glazed windows covering the majority of the south facade, (iv) a natural ventilation system (NVS) composed by ten automatized openings with different dimensions: four are located on the south facade, four on the north facade and two on the shed roof (north-oriented). To highlight the energy charge and discharge processes of the non-active slab, heat flux and temperature measurement techniques were implemented, along with airspeed measurements. Ten “measurement-poles” (MP) were distributed all over the concrete-floor surface. Each MP represented a zone of measurement, where air and surface temperatures, and convection and radiation heat fluxes, were intended to be measured. The airspeed was measured only at two points over the slab surface, near the south facade. To identify the heat transfer phenomena that take part in the charge and discharge process, some relevant dimensionless parameters were used, along with statistical analysis; heat transfer phenomena were identified based on this analysis. Experimental data, after processing, had shown that two periods could be identified at a glance: charge (heat gain, positive values) and discharge (heat losses, negative values). During the charge period, on the floor surface, radiation heat exchanges were significantly higher compared with convection. On the other hand, convection heat exchanges were significantly higher than radiation, in the discharge period. Spatially, both, convection and radiation heat exchanges are higher near the natural ventilation openings and smaller far from them, as expected. Experimental correlations have been determined using a linear regression model, showing the relation between the Nusselt number with relevant parameters: Peclet, Rayleigh, and Richardson numbers. This has led to the determination of the convective heat transfer coefficient and its comparison with the convective heat coefficient resulting from measurements. Results have shown that forced and natural convection coexists during the discharge period; more accurate correlations with the Peclet number than with the Rayleigh number, have been found. This may suggest that forced convection is stronger than natural convection. Yet, airspeed levels encountered suggest that it is natural convection that should take place rather than forced convection. Despite this, Richardson number values encountered indicate otherwise. During the charge period, air-velocity levels might indicate that none air motion occurs, which might lead to heat transfer by diffusion instead of convection.Keywords: heat flux measurement, natural ventilation, non-active concrete slab, plus energy house
Procedia PDF Downloads 4141366 Origin of Hydrogen Bonding: Natural Bond Orbital Electron Donor-Acceptor Interactions
Authors: Mohamed Ayoub
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We perform computational investigation using density functional theory, B3LYP with aug-cc-pVTZ basis set followed by natural bond orbital analysis (NBO), which provides best single “natural Lewis structure” (NLS) representation of chosen wavefunction (Ψ) with natural resonance theory (NRT) to provide an analysis of molecular electron density in terms of resonance structures (RS) and weights (w). We selected for the study a wide range of gas phase dimers (B…HA), with hydrogen bond dissociation energies (ΔEB…H) that span more than two orders of magnitude. We demonstrate that charge transfer from a donor Lewis-type NBO (nB:) to an acceptor non-Lewis-type NBO (σHA*) is the primary cause for H-bonding not classical electrostatic (dipole-dipole or ionic). We provide a variety of structure, and spectroscopic descriptors to support the conclusion, such as IR frequency shift (ΔνHA), H-bond penetration distance (ΔRB..H), bond order (bB..H), charge-transfer (CTB→HA) and the corresponding donor-acceptor stabilization energy (ΔE(2)).Keywords: natural bond orbital, hydrogen bonding, electron donor, electron acceptor
Procedia PDF Downloads 4351365 Mordechai Vanunu: “The Atomic Spy” as a Nuclear Threat to Discourse in Israeli Society
Authors: Ada Yurman
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Using the case of Israeli Atomic Spy Mordechai Vanunu as an example, this study sought to examine social response to political deviance whereby social response can be mobilized in order to achieve social control. Mordechai Vanunu, a junior technician in the Dimona Atomic Research Center, played a normative role in the militaristic discourse while working in the “holy shrine” of the Israeli defense system for many years. At a certain stage, however, Vanunu decided to detach himself from this collective and launched an assault on this top-secret circle. Israeli society in general and the security establishment in particular found this attack intolerable and unforgivable. They presented Vanunu as a ticking time bomb, delegitimized him and portrayed him as “other”. In addition, Israeli enforcement authorities imposed myriad prohibitions and sanctions on Vanunu even after his release from prison – “as will be done to he who desecrates holiness.” Social response to Vanunu at the time of his capture and trial was studied by conducting a content analysis of six contemporary daily newspapers. The analysis focused on use of language and forms of expression. In contrast with traditional content analysis methodology, this study did not just look at frequency of expressions of ideas and terms in the text and covert content; rather, the text was analyzed as a structural whole, and included examination of style, tone and unusual use of imagery, and more, in order to uncover hidden messages within the text. The social response to this case was extraordinarily intense, not only because in this case of political deviance, involving espionage and treason, Vanunu’s actions comprised a real potential threat to the country, but also because of the threat his behavior posed to the symbolic universe of society. Therefore, the response to this instance of political deviance can be seen as being part of a mechanism of social control aiming to protect world view of society as a whole, as well as to punish the criminal.Keywords: militarism, political deviance, social construction, social control
Procedia PDF Downloads 1111364 Ab Initio Calculation of Fundamental Properties of CaxMg1-xA (a = Se and Te) Alloys in the Rock-Salt Structure
Authors: M. A. Ghebouli, H. Choutri, B. Ghebouli , M. Fatmi, L. Louail
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We employed the density-functional perturbation theory (DFPT) within the generalized gradient approximation (GGA), the local density approximation (LDA) and the virtual-crystal approximation (VCA) to study the effect of composition on the structure, stability, energy gaps, electron effective mass, the dynamic effective charge, optical and acoustical phonon frequencies and static and high dielectric constants of the rock-salt CaxMg1-xSe and CaxMg1-xTe alloys. The computed equilibrium lattice constant and bulk modulus show an important deviation from the linear concentration. From the Voigt-Reuss-Hill approximation, CaxMg1-xSe and CaxMg1-xTe present lower stiffness and lateral expansion. For Ca content ranging between 0.25-0.75, the elastic constants, energy gaps, electron effective mass and dynamic effective charge are predictions. The elastic constants and computed phonon dispersion curves indicate that these alloys are mechanically stable.Keywords: CaxMg1-xSe, CaxMg1-xTe, band structure, phonon
Procedia PDF Downloads 5401363 Numerical Analysis of Charge Exchange in an Opposed-Piston Engine
Authors: Zbigniew Czyż, Adam Majczak, Lukasz Grabowski
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The paper presents a description of geometric models, computational algorithms, and results of numerical analyses of charge exchange in a two-stroke opposed-piston engine. The research engine was a newly designed internal Diesel engine. The unit is characterized by three cylinders in which three pairs of opposed-pistons operate. The engine will generate a power output equal to 100 kW at a crankshaft rotation speed of 3800-4000 rpm. The numerical investigations were carried out using ANSYS FLUENT solver. Numerical research, in contrast to experimental research, allows us to validate project assumptions and avoid costly prototype preparation for experimental tests. This makes it possible to optimize the geometrical model in countless variants with no production costs. The geometrical model includes an intake manifold, a cylinder, and an outlet manifold. The study was conducted for a series of modifications of manifolds and intake and exhaust ports to optimize the charge exchange process in the engine. The calculations specified a swirl coefficient obtained under stationary conditions for a full opening of intake and exhaust ports as well as a CA value of 280° for all cylinders. In addition, mass flow rates were identified separately in all of the intake and exhaust ports to achieve the best possible uniformity of flow in the individual cylinders. For the models under consideration, velocity, pressure and streamline contours were generated in important cross sections. The developed models are designed primarily to minimize the flow drag through the intake and exhaust ports while the mass flow rate increases. Firstly, in order to calculate the swirl ratio [-], tangential velocity v [m/s] and then angular velocity ω [rad / s] with respect to the charge as the mean of each element were calculated. The paper contains comparative analyses of all the intake and exhaust manifolds of the designed engine. Acknowledgement: This work has been realized in the cooperation with The Construction Office of WSK "PZL-KALISZ" S.A." and is part of Grant Agreement No. POIR.01.02.00-00-0002/15 financed by the Polish National Centre for Research and Development.Keywords: computational fluid dynamics, engine swirl, fluid mechanics, mass flow rates, numerical analysis, opposed-piston engine
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