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The influence of temperature and size on the absorption coefficient of CdSe quantum dots
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Abstract<p>Because of Cadmium selenide quantum dots (CdSe quantum dots) has a tuning energy gap in the visible light range, therefore; it is provided a simple theoretical model for the absorption coefficient of CdSe quantum dots, where the absorption coefficient determines the extent to which the light of a material can penetrate a specific wavelength before it is absorbed. CdSe quantum dots have an energy gap can be controlled through two effects: the temperature and the dot size of them. It is found that; there is an absorption threshold for each directed wavelength, where CdSe quantum dots begin to absorb the visible spectrum at a size of 1.4 nm at room temperature for a directed wavelength 300 nm. It has been observed that; when the wavelength is increasing its absorption threshold is increased. For wavelengths (400, 500, 600) nm, the absorption thresholds for each quantum sizes are (1.8, 2.2. 3.2)nm respectively. On the other hand, a rising of the temperature led to reduces the absorption coefficient value, that at 400 K for all quantum sizes, the absorption coefficient increases >2000cm<sup>−1</sup>(According to the directed wavelength) than it is at 0 K. CdSe quantum dots can be considered as one of the most promising materials because it has a tuning gap for the visible wavelengthsfor different applications, such as light-emitting diodes in different colors of the visible spectrum. It is found that; there is a good agreement between our theoretical calculations and experimental results.</p>
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Publication Date
Fri Apr 01 2016
Journal Name
Journal Of Engineering
Estimation of Mass Transfer Coefficient for Copper Electrowinning Process
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Mass transfer was examined at a stationary rectangular copper electrode (cathode) by using the reduction of cupric ions as the electrochemical reaction. The influence of electrolyte temperature (25, 45, and 65 oC), and cupric ions concentration (4, 8, and 12 mM) on mass transfer coefficient were investigated by using limiting current technique. The mass transfer coefficient and hence the Sherwood number was correlated as Sh =

 

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Publication Date
Fri Mar 01 2024
Journal Name
Physical Chemistry Research
Exploring the Potential of Quantum Chemical Calculations for Synthesized Quinazoline Derivatives as Superior Corrosion Inhibitors in Acidic Environment
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Hydrochloric acid (HCl) is a substance that is frequently utilized in industrial operations for important tasks such as chemical cleaning and pickling metallic surfaces.Therefore, the corrosion inhibition ability of three newly synthesized quinazoline derivatives namely, 3-allyl-2-(propylthio) quinazolin-4(3H)-one) (APQ), (3-allyl-2-(allylthio) quinazolin-4(3H)-one) (AAQ), (3-allyl- 2-( Prop -2-yn -1-ylthio) Quinazolin - 4 (3H) - one) (AYQ) were theoretically determined and these compounds were characterized using Fourier Transform Infra-Red (FTIR) and 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic. A series of quantum chemical properties of these derivatives: EHOMO, ELUMO, energy gap (ΔE),dipole moment (μ), hardness (η), soft

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Publication Date
Thu Jun 01 2023
Journal Name
Baghdad Science Journal
Design and construction of anair pollution detection system using a laser beam and absorption spectroscopy
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Air pollution is one of the important problems facing Iraq. Air pollution is the result of uncontrolled emissions from factories, car exhaust electric generators, and oil refineries and often reaches unacceptable limits by international standards. These pollutants can greatly affect human health and regular population activities. For this reason, there is an urgent need for effective devices to monitor the molecular concentration of air pollutants in cities and urban areas. In this research, an optical system has been built consisting of aHelium-Neonlaser,5mWand at 632.8 nm, a glass cell with a defined size, and a power meter(Gentec-E-model: uno) where a scattering of the laser beam occurs due to air pollution. Two pollutants were examin

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Publication Date
Wed Mar 16 2016
Journal Name
Iraqi Journal Of Agricultural Sciences
INFLUENCE OF WHEY FOLIAR SPRAYING AND GROWING POINT PINCHING ON GROWTH AND YIELD PARAMETERES OF OKRA
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An experiment was carried out in the fields that belong to agiriculture college /Baghdad university (AL-Jadyria) according to randomized compeleted blocks design(R.C.B.D.) with three replications during the spring season of 2015 to Study impact of growing point pinching and foliar spraying of whey on some traits of vegetative growth and yield of okra(Abelmoschus esculentus L.Moench) AL-Batra local cultivar.The experiment was included six treatments which was pinching or no pinching of growthing point and foliar spraying of whey with three concentration (0%,50%and75%).The results showed that pinching was siginificant in all traits of vegetative growth except plant High where the highest values of branches number , diameter of stem and leafe

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Publication Date
Mon Mar 01 2010
Journal Name
Al-khwarizmi Engineering Journal
Estimation of Extract Yield and Mass Transfer Coefficient in Solvent Extraction of Lubricating Oil
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An investigation was conducted to suggest relations for estimating yield and properties of the improved light lubricating oil fraction produced from furfural extraction process by using specified regression.

Mass transfer in mixer-settler has been studied. Mass transfer coefficient of continuous phase, mass transfer coefficient of dispersed phase and the overall mass transfer coefficient extraction of light lubes oil distillate fraction by furfural are calculated in addition to all physical properties of individual components and the extraction mixtures.

The effect of extraction variables were studied such as extraction temperature which ranges from 70 to 110°C and solvent to oil ratio which ranges from 1:1 to 4:1 (wt/wt

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Publication Date
Mon Apr 18 2022
The modeling techniques of the second‐order correlation function <i>g</i> <sup>(2)</sup> ( <i>τ</i> ) for a quantum emitter
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Publication Date
Sat Apr 29 2023
Journal Name
International Journal Of Biomaterials
The Influence of the Hyaluronic Acid Gel on the Postoperative Sequelae following Surgical Removal of the Impacted Mandibular Third Molar in Comparison with the A-PRF: A Randomized Controlled Trial
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One of the most common procedures in oral surgery is the removal of impacted mandibular third molars, often followed by pain, swelling, alveolitis, and trismus. Purpose. To compare the outcomes of the intrasocket application of 1% hyaluronic acid oral gel (HA) and advanced platelet-rich fibrin (A-PRF) on the expected postoperative complications, pain, swelling, and trismus follow the surgical extraction of the impacted mandibular third molar. Material and Methods. A randomized controlled trial was conducted at the Oral and Maxillofacial Surgery Unit, Dental Teaching Hospital. Healthy patients who required surgical removal of the impacted mandibular third molar were divided randomly into three groups. The extraction site of the group

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Publication Date
Sat Apr 01 2023
Journal Name
Baghdad Science Journal
A Study of a-Si:H Absorption Edge Using Dunstan’s Model
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The optical absorption data of Hydrogenated Amorphous Silicon was analyzed using a Dunstan model of optical absorption in amorphous semiconductors. This model introduces disorder into the band-band absorption through a linear exponential distribution of local energy gaps, and it accounts for both the Urbach and Tauc regions of the optical absorption edge.Compared to other models of similar bases, such as the O’Leary and Guerra models, it is simpler to understand mathematically and has a physical meaning. The optical absorption data of Jackson et al and Maurer et al were successfully interpreted using Dunstan’s model. Useful physical parameters are extracted especially the band to the band energy gap , which is the energy gap in the a

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Publication Date
Fri Jun 02 2017
Journal Name
Kufa Journal Of Engineering
COMPRESSIVE STRENGTH OF CONCRETE CONTAINING WATER ABSORPTION POLYMER BALLS (WAPB)
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Water absorbent polymers (WAP) are new component in producing building materials. They provide internal curing which reduces autogenous cracking, eliminates autogenous shrinkage, mortar strength increased, enhance early age strength to withstand strain, improve the durability, introduce higher early age compressive strength, have higher performance and reduce the effect of insufficient external curing. This research used different percent of polymer balls to choose the percent that provides good development in compressive strength with time for both water and air curing. The water absorption polymer balls in this research have the ability to absorb water and after usage in concrete they spill out the water (internal curing) and shri

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Publication Date
Wed Sep 30 2009
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Prediction of Effective Bed Thermal Conductivity and Heat Transfer Coefficient in Fluidized Beds
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Experimental study of heat transfer coefficients in air-liquid-solid fluidized beds were carried out by measuring the heat rate and the overall temperature differences across the heater at different operating conditions. The experiments were carried out in Q.V.F. glass column of 0.22 m inside diameter and 2.25 m height with an axially mounted cylindrical heater of 0.0367 m diameter and 0.5 m height. The fluidizing media were water as a continuous phase and air as a dispersed phase. Low density (Ploymethyl-methacrylate, 3.17 mm size) and high density (Glass beads, 2.31 mm size) particles were used as solid phase. The bed temperature profiles were measured axially and radially in the bed for different positions. Thermocouples were connecte

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