Theoretical Adjustment of Necessary Conditions for Enhancing Figure of Merit of Thin Thermoelectric Layers

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Taher Ghrib ◽  
Munirah Abdullah Almessiere ◽  
Amal Lafy Al-Otaibi ◽  
Sami Brini ◽  
Radhouane Chtourou
Keyword(s):  
Figure Of Merit ◽  
Diffusion Length ◽  
Necessary Conditions ◽  
Preparation Process ◽  
Experimental Conditions ◽  
Simple Method ◽  
Thermal Properties Of Materials ◽  
Properties Of Materials ◽  
Photothermal Deflection

This work presents a simple method based on electrical and thermal properties of materials. It permits researchers, in the field of manufacturing and characterization of thin and thick films in solid state to take appropriate experimental conditions before the preparation process. The calculation of the thermal diffusion length, its comparison with thicknesses of the substrate, the thin layer deposited on the substrate, the use of photothermal deflection technique, and the Cahill's law permit to highlight the necessary conditions that allow researchers to manufacture samples with high thermoelectric power such as the required thickness, electric conductivity, and thermal conductivity.

EBIC Measurements of Minority Carrier Diffusion Length in a Gan-based Light Emitting Diode

2001 ◽  
Vol 7 (S2) ◽  
pp. 566-567
Author(s):  
K.L. Bunker ◽  
J.C. Gonzalez ◽  
P.E. Russell
Keyword(s):  
Diffusion Length ◽  
Light Emitting Diode ◽  
Analysis Model ◽  
Electrical And Optical Properties ◽  
Experimental Conditions ◽  
Minority Carrier Diffusion Length ◽  
Light Emitting ◽  
Electron Beam Induced Current ◽  
Minority Carriers

This study involved the application of the Scanning Electron Microscope (SEM) for the characterization of a GaN-based Light Emitting Diode (LED) by the Electron Beam Induced Current (EBIC) method. The diffusion length of the minority carriers in both the p and n-type regions of a GaN-based LED structure was determined with the EBIC technique in the line scan configuration. The diffusion length is a critical physical parameter that directly affects the electrical and optical properties of these devices. This value is generally understood to be a material property of the layers within a device. However, the measured values of the diffusion length are sensitive to the sample design, experimental conditions, measurement technique, and data analysis model and method utilized.The EBIC measurements were performed at room temperature in a Hitachi S-3200N SEM using a GW Electronics Type 31 Specimen Current Amplifier.

scholarly journals Rapid characterization of the propagation of COVID-19 in different countries

2020 ◽  
Author(s):  
Patricio Vargas ◽  
Sebastián Allende ◽  
Eugenio E. Vogel ◽  
Sigismund Kobe
Keyword(s):  
Mortality Rate ◽  
Figure Of Merit ◽  
Gaussian Function ◽  
Disease Status ◽  
List Type ◽  
Simple Method ◽  
Bcg Vaccination ◽  
The Status ◽  
Order Of Magnitude

ABSTRACTBACKGROUNDCOVID-19 has spread rapidly, and there are still many characteristics of this new disease to be unveiled. We propose a simple method to calculate a “figure of merit” FC to provide an early characterization of the disease status in country C.METHODSWe use mathematical tools to adjust a Gaussian function to the daily increase of infected patients. Maximum value and full width half maximum of the Gaussian are characteristics of the development of the development of the pandemic in each country. These parameters are supplemented by the testing volume and the mortality rate to produce just one characterizing parameter: FC. In addition, the stability of the Gaussian fits was calculated within an entire week towards the end of the study period. Seventeen different countries were fully considered, while others are considered when discussing particular properties. Data employed is publically available.FINDINGSFitted Gaussian functions render effective information about the development of COVID-19. The number of critical days vary between 11 (South Korea) and 52 (Mexico). FC varies between 1 (Australia) and 899 (Mexico). The epidemic appears stabilized in some countries and unstable in others. Some large countries are experiencing fast development of the propagation of the disease with high FC. A correlation between low (high) values of the mortality rate (and to some extent FC) and the presence (absence) of BCG vaccination is exposed.INTERPRETATIONThe adjustment of a Gaussian to daily data of COVID-19 in each country reveals the different propagation dynamics, properly characterized by the parameters proposed here. Testing plays a clear role to control the spread of the disease. Mortality rate spans more than one order of magnitude and is somewhat related to permanent massive BCG vaccination. The figure of merit, FC, introduced here spans more than 2 orders of magnitude which makes it a useful indicator to quickly find out the status of the pandemics in each territory. Geography plays a role: low population density and isolated countries can be efficient in controlling the spread of the disease.HIGHLIGHTSAn easy-to-evaluate parameter is defined to rapidly establish the status of the evolution of COVID-19 in any given territory. 17 countries in 4 continents are chosen to apply it and compare different evolutions.The parameter or figure of merit (FC) is dynamic: it combines testing, mortality rate, and characteristics of the Gaussian function that fits the new daily contagions.FC spans more than two orders of magnitude which makes it a very sensitive indicator to promptly detect second waves or local outbreaks.It is found that countries with massive BCG vaccination present low COVID-19 mortality rates and low values for FC.

A Simple Method for Estimation of Lipoxygenase and Cyclo-Oxygenase Pathways in Human Platelets - the Use of Thiobarbituric Acid Reaction

1980 ◽  
Vol 44 (02) ◽  
pp. 111-114 ◽  
Author(s):  
Hiroshi Takayama ◽  
Minoru Okuma ◽  
Haruto Uchino
Keyword(s):  
Time Course ◽  
Normal Values ◽  
Human Platelet ◽  
Thiobarbituric Acid ◽  
Human Platelets ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Simple Method ◽  
Acid Reaction ◽  
Optimal Ph

SummaryTo develop a simple method for estimation of platelet lipoxygenase (PLO) and cyclo-oxygenase (PCO) pathways, the arachidonic acid (AA) metabolism of human platelet was investigated under various experimental conditions by the use of the thiobarbituric acid (TBA) reaction and a radioisotope technique. A TBA-reactive substance different from malondialdehyde (MDA) via PCO pathway was detected and shown to be derived from the PLO pathway. Since the optimal pH and time course of its formation were different from those of MDA formation via PCO pathway, PLO and PCO pathways were estimated by quantitating the TBA-reactive substances produced by the incubation of AA either with aspirin-treated platelets or with untreated ones, respectively, each under optimal conditions. Normal values expressed in terms of nmol MDA/108 platelets were 1.17±0.34 (M±SD, n = 31) and 0.79±0.15 (n = 31) for PLO and PCO pathways, respectively.

scholarly journals Synthesis and characterization of a new ZIF-67@MgAl2O4 nanocomposite and its adsorption behaviour

RSC Advances ◽  
2021 ◽  
Vol 11 (22) ◽  
pp. 13245-13255
Author(s):  
Mehdi Davoodi ◽  
Fatemeh Davar ◽  
Mohammad R. Rezayat ◽  
Mohammad T. Jafari ◽  
Mehdi Bazarganipour ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnesium Aluminate ◽  
Synthesis And Characterization ◽  
Magnesium Aluminate Spinel ◽  
Adsorption Behaviour ◽  
Zeolitic Imidazolate Framework ◽  
Simple Method

New nanocomposite of zeolitic imidazolate framework-67@magnesium aluminate spinel (ZIF-67@MgAl2O4) has been fabricated by a simple method at room temperature with different weight ratios.

scholarly journals Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1757
Author(s):  
Yesica Vicente-Martínez ◽  
Manuel Caravaca ◽  
Antonio Soto-Meca ◽  
Miguel Ángel Martín-Pereira ◽  
María del Carmen García-Onsurbe
Keyword(s):  
Magnetic Nanoparticles ◽  
Nitrate Content ◽  
Adsorption Efficiency ◽  
Experimental Conditions ◽  
Dependent Behavior ◽  
Before And After ◽  
Naoh Solution ◽  
High Concentrations ◽  
Interference Studies

This paper presents a novel procedure for the treatment of contaminated water with high concentrations of nitrates, which are considered as one of the main causes of the eutrophication phenomena. For this purpose, magnetic nanoparticles functionalized with silver (Fe3O4@AgNPs) were synthesized and used as an adsorbent of nitrates. Experimental conditions, including the pH, adsorbent and adsorbate dose, temperature and contact time, were analyzed to obtain the highest adsorption efficiency for different concentration of nitrates in water. A maximum removal efficiency of 100% was reached for 2, 5, 10 and 50 mg/L of nitrate at pH = 5, room temperature, and 50, 100, 250 and 500 µL of Fe3O4@AgNPs, respectively. The characterization of the adsorbent, before and after adsorption, was performed by energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. Nitrates can be desorbed, and the adsorbent can be reused using 500 µL of NaOH solution 0.01 M, remaining unchanged for the first three cycles, and exhibiting 90% adsorption efficiency after three regenerations. A deep study on equilibrium isotherms reveals a pH-dependent behavior, characterized by Langmuir and Freundlich models at pH = 5 and pH = 1, respectively. Thermodynamic studies were consistent with physicochemical adsorption for all experiments but showed a change from endothermic to exothermic behavior as the temperature increases. Interference studies of other ions commonly present in water were carried out, enabling this procedure as very selective for nitrate ions. In addition, the method was applied to real samples of seawater, showing its ability to eliminate the total nitrate content in eutrophized waters.

scholarly journals An Intrinsic Characterization of Five Points in a CAT(0) Space

2020 ◽  
Vol 8 (1) ◽  
pp. 114-165
Author(s):  
Tetsu Toyoda
Keyword(s):  
Metric Space ◽  
Isometric Embedding ◽  
Metric Spaces ◽  
Necessary Conditions ◽  
New Approach ◽  
Intrinsic Characterization ◽  
New Family

AbstractGromov (2001) and Sturm (2003) proved that any four points in a CAT(0) space satisfy a certain family of inequalities. We call those inequalities the ⊠-inequalities, following the notation used by Gromov. In this paper, we prove that a metric space X containing at most five points admits an isometric embedding into a CAT(0) space if and only if any four points in X satisfy the ⊠-inequalities. To prove this, we introduce a new family of necessary conditions for a metric space to admit an isometric embedding into a CAT(0) space by modifying and generalizing Gromov’s cycle conditions. Furthermore, we prove that if a metric space satisfies all those necessary conditions, then it admits an isometric embedding into a CAT(0) space. This work presents a new approach to characterizing those metric spaces that admit an isometric embedding into a CAT(0) space.

scholarly journals Experimental Study on the Water Selective Dense Membrane under an Absolute Pressure Difference with Simplified Test Method

2021 ◽  
Vol 11 (4) ◽  
pp. 1710
Author(s):  
Jinwook Lee ◽  
Hyo-Sun Kim ◽  
Donik Ku ◽  
Jihun Lim ◽  
Minkyu Jung ◽  
...  
Keyword(s):  
Measurement Methods ◽  
Test Method ◽  
Coefficient Of Performance ◽  
Absolute Pressure ◽  
Air Conditioner ◽  
Experimental Conditions ◽  
Simple Method ◽  
Performance Factors ◽  
Dense Membrane ◽  
Before And After

Membrane-based vacuum dehumidification technology is currently being actively studied. In most studies, the performance of the membrane-based systems is evaluated under the assumption that the membrane can achieve ideal separation, which results in ideal coefficient of performance (COP) values. However, the performance factors for membranes vary depending on the experimental conditions and measurement methods. Therefore, relevant values can only be calculated if the data are measured in an environment close to that of the application conditions. The cup measurement method is a simple method to measure the permeability, however, there are limitations regarding adding variables during the experiment. To overcome these limitations, a new experimental device was constructed that combines pressurized cell with the cup method. Using the device, the performance of polyethylene-amide-bonded dense membranes was evaluated under conditions where absolute pressure differentials occurred before and after the membrane, such as in air conditioner dehumidification systems.

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