Function Of Temperature Research Articles

A Comment on the Utility of Nanofluids: Interactive Influence of Nanoparticle Size and Amount at Varying Temperatures

Interactive influence of nanoparticle diameter, dp and volumetric fraction, φ on major thermophysical characteristics of relative thermal conductivity, kr and dynamic viscosity, μr of nanofluids as a primary function of temperature, T is determined to assess the utility of nanofluids. In the case study common base fluids of water (W) and ethylene glycol (EG) are used. Spherical shape Ag and Al2O3 with a selected dp range of (20–100 nm) are used in the covered φ range of (0.25–5%). Influence of T is set by considering T = 293 K and T = 323 K. The referred data ranges are applied for the calculation of kr and μr of nanofluids Ag–W, EG and Al2O3–W, EG in reference to a calculation procedure provided previously by the authors. The calculated magnitudes of kr and μr are expressed as a function of dp, φ and T. The results reveal that kr and μr rise dramatically as dp decrease from 40 nm to 20 nm and φ increase from 2% to 5% at T = 293 K and T = 323 K. The calculations confirm the relevant literature that the required pumping power increase is associated with low dp and high φ. Therefore, here exists limiting magnitudes of dp, φ as a function of T for the effective utilization of nanoparticles in base fluids. In order to generalize the fact non-dimensional parameters of Prandtl Number, Pr and Reynolds Number, Re should be referred due to the definitions of each depend on thermophysical characteristics and the cited dp, φ and T. The calculations herein have the validity range of Re and Pr of base fluids as 0.0002–0.032 and 3.58–210.30, respectively.

Diazo-coupling Reaction Between 2-Aminothiazole and Thymol; Synthesis, DFT Studies, and Specific Heat Capacity Calculations Using TGA-DSC

Aims: This study aimed at determining the synthesis, DFT studies, and specific heat capacity (Cp) of azo dyes composed of derivatives of 2-aminothiazole and thymol. Background: To date, azo dyes have transitioned from the science of molecules to the science of materials very elegantly. 2-aminothiazole and thymol have a wide biological application window. Therefore, attempts have been made to couple these two biologically important organic frameworks via a diazotization strategy. Objective: The objective of this study was to explore thymol as a coupling partner for the synthesis of azo dyes via a diazotization strategy. Furthermore, the structures of the synthesized azo dyes have been confirmed using DFT calculations. In addition, thermal profiles (TGA-DSC) have been explored elegantly to calculate specific heat capacity (Cp) as a function of temperature for the synthesized azo dyes. Methods: A unit operation, i.e., diazotization, has been tuned very aptly for the formation of azodye framework based on 2-aminothymol and thymol. Thereafter, the thermal stability of the synthesized azo dyes has been addressed using TGA-DSC. Moreover, the Density Functional Theory has also been used to confirm vibrational frequencies of the synthesized azo dyes. Results: In the present work, the effect of electronic parameters on the melting temperature of the corresponding azo dyes has been comprehended with the help of DSC analysis. Specific heat capacity data as a function of temperature for the synthesized dyes have been reported for the first time. Conclusion: Melting behavior of the synthesized azo dyes is determined based on electronic effects with the help of thermal analysis. The specific heat capacity data can be helpful for the chemists, those engaged in chemical modelling, as well as for further docking studies. The structures of these synthesized azo dyes have been confirmed by performing DFT calculations, and to our delight, the comparison of both the experimental and calculated vibrational frequency data is found in good agreement with each other.

An FT-IR Based Investigation of Trehalose Mediated Thermal Stabilisation of Bacillus clausii

Background: Fourier Transform InfraRed spectroscopy analysis on Bacillus clausii and Bacillus clausii in the presence of trehalose are reported. Objective: In order to characterize the thermal response of such systems the InfraRed technique was employed to collect the spectra from 25.0°C to 80.0°C in the 4000 cm-1-400 cm-1 spectral range. Methods: The data analysis was performed focusing the attention to the intramolecular OH stretching vibrational region by means evaluating the spectral distance as a function of temperature. Results: From this analysis it emerges that the thermal restraint of Bacillus clausii in the presence of trehalose is higher in respect to Bacillus clausii alone. Conclusion: Such a result, which confirms the bioprotective role of trehalose against external temperature changes, provides useful information for the applications of the disaccharide in food industry.

Specific Heat Capacity Estimations for Biologically and Medicinally Important Compounds: Lidocaine Hydrochloride, Clove Oil and β-Piperine Using the DSC Technique

Aim: To study the specific heat capacity for biologically and medicinally important compounds, namely, lidocaine hydrochloride, clove oil and beta-Piperine using the DSC technique. Background: One of the main problems in the science of medicine is the application of drug molecules with limited solubility in water and in biofluids. Solubility is related to the chemical potential of the solutes involved, which imparts free energy avenues, a necessary requirement for equilibrium processes. The convincing solutions for solving this issue are the utilization of ionic liquids as a drug. Lidocaine is the most widely utilized intraoral injected dental anesthetic prior to performing painful medical procedures. Besides that, lidocaine hydrochloride is a salt, having a melting point of 76°C (349 K) and behaves as an ionic liquid after melting. Clove oil and β-piperine are very well-known naturally occurring medicinal compounds having a broad spectrum of applications. Objective: To study the thermal gravimetry analysis behaviour for lidocaine hydrochloride, clove oil and β-piperine. To compute specific heat capacity at constant pressure, as a function of temperature for the studied systems. Methods: In the present communication, the studies of Thermal Gravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC) for these compounds are described. Results: The data of heat flow have been utilized to obtain specific heat capacity (Cp) values for lidocaine hydrochloride, clove oil and β-piperine over a temperature range between 75°C (348 K) and 155°C (428 K) based upon the methodology we have developed. Conclusion: LC•HCl behaves as an ionic liquid between 76 and 230°C (349 and 503 K). Clove oil shows lower specific heat capacity values and is similar to other organic aromatic compounds while piperine exhibits comparative high specific heat capacity values indicating possibilities of intramolecular hydrogen bonding, which is generally not affected by temperature.

Thermal Mechanical and Morphological Analysis of the Reinforced Composite Material Jute/Basalt

In the current report, study has been conducted on the preparation and characterization of jute/basalt reinforced composites as a novel polymer matrix. The material is prepared by hand layup technique by considering the orthogonal L27 array, with 3 stages and 4 process parameters. Mechanical properties such as tensile and bending are determined and the optimal structure is evaluated by the Taguchi process. To analyze the impact of the fibre sheet, a detailed physio-chemical, thermal, morphological and mechanical characterization of the jute/basalt reinforced composite material is performed. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential calorimetry scanning (DSC) are characterized. FTIR analysis is used to identify additives after extraction from a polymer matrix and contamination on or in a material. In order to know the amount of heat needed to raise the temperature of a sample, DSC analysis is carried out and reference is determined as a function of temperature. Similarly, DSC analysis provides information regarding Transition temperatures, glass transitions, Polymorphic transformation. The microstructural properties of the fibres appeared significantly dependent upon the relative blend ratio. DSC revealed that good interaction/miscibility existed between the two polymers. Tensile strength characterization showed that the value increased over one order of magnitude with the addition of PU in the polymer matrix, attributed to the formation of inter-fibre bonds.

Samarium Oxide at High Temperatures: Sublimation and Thermodynamics

Vaporization processes and thermodynamic properties of samarium oxide over the temperature range 2265–2668 K have been studied by means of high-temperature mass spectrometry. The values of vaporization enthalpy of Sm2O3 and enthalpy of formation of samarium monoxide at 298 K have been determined. Dependencies of partial pressures of SmO and Sm over Sm2O3 as functions of temperature have been obtained over the above-mentioned range.

New particle formation from sulfuric acid and ammonia: nucleation and growth model based on thermodynamics derived from CLOUD measurements for a wide range of conditions

Abstract. Understanding new particle formation and growth is important because of the strong impact of these processes on climate and air quality. Measurements to elucidate the main new particle formation mechanisms are essential; however, these mechanisms have to be implemented in models to estimate their impact on the regional and global scale. Parameterizations are computationally cheap ways of implementing nucleation schemes in models, but they have their limitations, as they do not necessarily include all relevant parameters. Process models using sophisticated nucleation schemes can be useful for the generation of look-up tables in large-scale models or for the analysis of individual new particle formation events. In addition, some other important properties can be derived from a process model that implicitly calculates the evolution of the full aerosol size distribution, e.g., the particle growth rates. Within this study, a model (SANTIAGO – Sulfuric acid Ammonia NucleaTIon And GrOwth model) is constructed that simulates new particle formation starting from the monomer of sulfuric acid up to a particle size of several hundred nanometers. The smallest sulfuric acid clusters containing one to four acid molecules and a varying amount of base (ammonia) are allowed to evaporate in the model, whereas growth beyond the pentamer (five sulfuric acid molecules) is assumed to be entirely collision-controlled. The main goal of the present study is to derive appropriate thermodynamic data needed to calculate the cluster evaporation rates as a function of temperature. These data are derived numerically from CLOUD (Cosmics Leaving OUtdoor Droplets) chamber new particle formation rates for neutral sulfuric acid–water–ammonia nucleation at temperatures between 208 and 292 K. The numeric methods include an optimization scheme to derive the best estimates for the thermodynamic data (dH and dS) and a Monte Carlo method to derive their probability density functions. The derived data are compared to literature values. Using different data sets for dH and dS in SANTIAGO detailed comparison between model results and measured CLOUD new particle formation rates is discussed.

Glow discharge effect on temperature and time of treatment for the synthesis of Mo-doped manganite

We report the synthesis of CaMn0.9Mo0.1O3 manganite by glow discharge (GD) plasma treatment under Argon-Air atmosphere. The morphological, structural and magnetic properties were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and magnetization measures. The results from these measures reveal that the properties of GD synthesized manganite are similar to that exhibited by CaMn0.9Mo0.1O3 produced by conventional resistive furnace. The Rietveld analysis of XRD patterns performed at room temperature show that the samples crystallize in orthorhombic structure of Pnma (62) space group. The magnetization curves as a functionof temperature show two inflection points related to paramagnetic-antiferromagnetic and structural transition. The GD treatment produces a compound with similar properties, reducing the time and energy consumption in comparison with conventional synthesis route by using resistive furnace.

Boron-doping of cubic SiC for intermediate band solar cells: a scanning transmission electron microscopy study

Boron (B) has the potential for generating an intermediate band in cubic silicon carbide (3C-SiC), turning this material into a highly efficient absorber for single-junction solar cells. The formation of a delocalized band demands high concentration of the foreign element, but the precipitation behavior of B in the 3C polymorph of SiC is not well known. Here, probe-corrected scanning transmission electron microscopy and secondary-ion mass spectrometry are used to investigate precipitation mechanisms in B-implanted 3C-SiC as a function of temperature. Point-defect clustering was detected after annealing at 1273 K while stacking faults, B-rich precipitates and dislocation networks developed in the 1573 - 1773 K range. The precipitates adopted the rhombohedral B13C2 structure and trapped B up to 1773 K. Above this temperature, higher solubility reduced precipitation and free B diffused out of the implantation layer. Dopant concentrations of \mathbf{10^{19}\:\mathrm{\mathbf{at.cm}}^{-3}}1019𝐚𝐭.𝐜𝐦−3 were achieved at 1873 K.

The Effect of Glass Composition Containing RE Oxide Waste Glass on Liquidus Temperature

ABSTRACTThe liquidus temperature (TL) of rare earth (RE) was determined for alumino-borosilicate glasses for treating americium and curium that have been studied previously. Their work covers a wide range of glass composition with various crystalline phases as primary phase. Present work is aimed at understanding the effect of glass composition on TL for waste glasses designed for vitrifying RE oxides wastes. In a sufficiently narrow composition region, this effect can be represented by a first-order model fitted measured TL versus composition data. Test glasses were formulated by varying of component fractions one-at-a-time. The glasses contained SiO2, B2O3, and Al2O3 as glass formers and Nd2O3 with CeO2 as simulated RE waste. Twenty glasses were made to investigate crystallization as a function of temperature and glass composition. The primary crystalline phase was Ce-borosilicate (Ce3BSi2O10), secondary phases were Al-containing crystals (Al2O3 and Al10Si2O19), and crystalline CeO2. A first-order model was fitted to crystal fraction versus glass composition data. Generally, SiO2 and B2O3 tend to suppress crystallization, Al2O3 has little effect, and, as expected, RE components (Nd2O3 and CeO2) promote it. The correlation coefficient, R2, was 0.89 for the primary crystalline phase TL as a linear function of composition.

Simulated magnetocaloric properties of MnCr2O4 spinel

The magnetocaloric properties of MnCr2O4 spinel have been simulated based on a phenomenological model. The simulation of magnetization as function of temperature is used to explore magnetocaloric properties such as magnetic entropy change, heat capacity change, and relative cooling power. The results imply the prospective application of MnCr2O4 spinel to achieve magnetocaloric effect at cryogenic temperatures (20-60K) near Curie temperatures (38-44K). According to the obtained results it is recommended that MnCr2O4 spinel can be used as a promising practical material in the active magnetic regenerator cycle that cools hydrogen gas.

The influence of alkyl polyglucosides (and highly ethoxylated alcohol boosters) on the phase behavior of a water/toluene/technical alkyl polyethoxylate microemulsion system

The influence of additives (alkyl polyglucoside, Glucopon 600 CS UP and alcohol ethoxylate C18E100) on the behavior of the water/toluene/Lutensol ON 50 (technical oxoalcohol, i-C10E5) microemulsion system as a function of temperature and composition has been investigated. The phase behavior of the microemulsions was determined by vertical sections through the Gibbs phase prism (fish-like phase diagrams). Alkyl polyglucoside shifts the one phase region to lower temperatures compared with water/toluene/Lutensol ON 50 mixtures. This is contrary to the expectation, considering the extreme hydrophilic nature of the sugar headgroup. The addition of hydrophilic alcohol ethoxylate (C18E100) to the water/toluene/Lutensol ON 50 system increases the solubilization capacity of the surfactant, even if the co-surfactant is used in small quantities, and shifts the one-phase region to higher temperature by a few degrees Celsius.

Influence of variable heat transfer coefficient of fireworks and crackers on thermal explosion critical ambient temperature and time to ignition

To study the effect of variable heat transfer coefficient of fireworks and crackers on thermal explosion critical ambient temperature and time to ignition, considering the heat transfer coefficient as the power function of temperature, mathematical thermal explosion steady state and unsteady-state model of finite cylindrical fireworks and crackers with complex shell structures are established based on two-dimensional steady state thermal explosion theory. The influence of variable heat transfer coefficient on thermal explosion critical ambient temperature and time to ignition are analyzed. When heat transfer coefficient is changing with temperature and in the condition of natural convection heat transfer, critical ambient temperature lessen, thermal explosion time to ignition shorten. If ambient temperature is close to critical ambient temperature, the influence of variable heat transfer coefficient on time to ignition become large. For firework with inner barrel in example analysis, the critical ambient temperature of propellant is 463.88 K and the time to ignition is 4054.9s at 466 K, 0.26 K and 450.8s less than without considering the change of heat transfer coefficient respectively. The calculation results show that the influence of variable heat transfer coefficient on thermal explosion time to ignition is greater in this example. Therefore, the effect of variable heat transfer coefficient should be considered into thermal safety evaluation of fireworks to reduce potential safety hazard.

Interaction of Aqueous Solution of Sulphamethoxazole Drug with Diglycine by Volumetric Method at Different Temperatures

Abstract The interaction of diglycine with sulphamethoxazole drug as a function of temperature and concentration have been investigated by volumetric method. The density of ternary mixture of diglycine (0.002–0.01 mol · kg –1) in aqueous sulphamethoxazole drug (0.001–0.01 mol · kg –1) solution have been measured using Anton Paar DSA 5000 instrument at T = (288.15 to 308.15) K. The apparent molar volumes V φ , partial molar volume at infinite dilution V φ 0, transfer partial molar volume Δ tr V φ ○, partial molar expansibility E 2 o , thermal expansion coefficient α 2, and Hepler's constant (∂C P ∞/∂P) T are calculated from density data. The above parameters are used to interpret the solute-solute and solute-solvent interactions of diglycine in aqueous solution of sulphamethoxazole drug. Hydration number and interaction coefficients have also been calculated from these data. Dehydration of diglycine is observed, rising with the temperature and drug molality. These results are explained on the basis of drug-water-amino acid interactions. The data suggest that interaction between ions and charged/hydrophilic groups are predominant.

Microstructural and dielectrical characterization of Ho doped BaTiO3 ceramics

The Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt % Ho, were investigated regarding their microstructural and dielectric characteristics. Doped BaTiO3 were prepared using conventional solid state reaction and sintered at 1380?C for four hours. SEM analysis of Ho/BaTiO3 doped ceramics showed that the low doped samples exhibit mainly fairly uniform and homogeneous microstructure with the grain size ranged from 20-40 ?m. In the samples with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2-10 ?m. Measurements of dielectric properties were carried out as a function of temperature up to 180 ?C at different frequencies. The samples doped with 0.01wt % of Ho, exhibit the high value of dielectric permittivity (?r = 2160) at room temperature. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss law and modified Curie-Weiss law the Curie constant (C), Curie temperature (Tc) and a critical exponent of nonlinearity (g) were calculated. The Curie temperature of doped samples were ranged from 128 to 130?C. The Curie constant for all series of samples decrease with increase of dopant concentration and the lowest values were observed on samples doped with 0.01 wt % of holmium.

MHD flow and heat transfer for Maxwell fluid over an exponentially stretching sheet with variable thermal conductivity in porous medium

An analysis is made to study MHD flow and heat transfer for Maxwell fluid over an exponentially stretching sheet through a porous medium in the presence of non-uniform heat source/sink with variable thermal conductivity. The thermal conductivity is assumed to vary as a linear function of temperature. The governing partial differential equations are transformed into ordinary differential equations using similarity transformations and then solved numerically using implicit finite difference scheme known as Keller-box method. The effect of the governing parameters on the flow field, skin friction coefficient, wall temperature gradient (in prescribed surface temperature case), wall temperature (in prescribed heat flux case) and Nusselt number are computed, analyzed and discussed through graphs and tables. The present results are found to be in excellent agreement with previously published work [1,2] on various special cases of the problem.

Viscosity Prediction for Solvent-Diluted Live Bitumen and Heavy Oil at Temperatures Up to 175-deg-C

Summary Accurate predictions of heavy-oil and bitumen viscosity as a function oftemperature, pressure, and composition are required for the design of thermaland solvent-based recovery methods. In this case study, the applicability ofthe recently developed Expanded Fluid (EF) viscosity model is tested onmeasured viscosities of diluted dead and live heavy oil and bitumen attemperatures from 20 to 175°C and pressures up to 10 MPa. Density and viscositydata were collected for a condensate solvent, dead (gas-free) bitumen, and deadheavy oil from western Canada, and for the corresponding live oils and dilutedmixtures of the dead and live oils with condensate solvent. Solubility,density, and viscosity data for heavy oil saturated with carbon dioxide(CO2) were obtained from the literature. The model was fitted to thedata of the dead oils and the condensate with average relative deviations lessthan 11%. The viscosity of the live bitumen and heavy oil was then predicted towithin 21 and 31% of the measured value on the basis of measured and calculatedlive-oil densities, respectively. Diluting the live and dead bitumen with 3 to30 wt% condensate or carbon dioxide reduced the viscosity by one to threeorders of magnitude, and the viscosities were predicted with an averagerelative deviation less than 16 and 24% on the basis of measured and calculatedmixture densities, respectively.

Suitable model for the calculation of the correlation between the real and the average specific heat capacity and possibilities of its application

Starting from the definition of the average specific heat capacity for chosen temperature range, the analytic dependence between the real and the mean specific heat capacities is obtained using differential and integral calculation. The obtained relation in differential form for the defined temperature range allows for the problem to be solved directly, without any special restrictions on its use. Using the obtained relation, a general model in the form of a polynomial of arbitrary degree in the function of temperature was derived, which has more suitable and faster practical application and is more general in character than the existing model. New graphical method for solving the problem is obtained based on differential geometry and using the derived equation. This may also have practical significance since many problems in thermodynamics are solved analytically and graphically. This result was used in order to obtain the amount of specific heat exchanged using an analytical model or a planimetric method. In addition, this graphical solution was used for the construction of the diagram showing the dependence between the specific heat exchanged and temperature. This diagram also gives a simple graphical procedure for the calculation of the real and the average specific heat capacity for arbitrary temperature or temperature interval. The confirmation for all graphic constructions is obtained using the differential properties between thermodynamic units. In order for the graphical solutions presented to be applicable in practice, suitable ratio coefficients have been determined for all cases. Verification of the model presented, as well as the possibilities of its application, were given using several characteristic examples of semi-ideal and real gas. Apart from linear and non-linear functions in the form of polynomials, the exponential function of the dependence between specific heat capacities and temperature was also analysed in this process.

Synthesis, characterization, and finite size effects on electricaltransport of nanoribbons of the charge density wave conductorNbSe3

NbSe3 exhibits remarkable anisotropy in most of its physical properties and has been a model systemfor studies of quasi-one-dimensional charge density wave (CDW) phenomena. Herein, wereport the synthesis, characterization, and electrical transport of single-crystallineNbSe3 nanoribbons by a facile one-step vapour transport process involving the transport of seleniumpowder onto a niobium foil substrate. Our investigations aid the understanding of the CDW natureof NbSe3 and the growth process of the material. They also indicate thatNbSe3 nanoribbons have enhanced CDW properties compared to those of the bulk phase due tosize confinement effects, thus expanding the search for new mesoscopic phenomena at thenanoscale level. Single nanoribbon measurements of the electrical resistance as a function oftemperature show charge density wave transitions at 59 and 141 K. We also demonstratesignificant enhancement in the depinning effect and sliding regimes mainly attributed tofinite size effects.

Study of electrical properties and the magnetoelectric effect inNi0.2Co0.8Fe2O4 + PbZr0.8Ti0.2O3 particulate composites

The electric properties and magnetoelectric effect in magnetoelectric (ME) composites with composition(x)Ni0.2Co0.8Fe2O4 + (1 − x)PbZr0.8Ti0.2O3 (PZT—lead zirconate titanate) were studied. The presence of single- (x = 0 and 1) andbi-phases (x = 0.15, 0.30 and 0.45) in the composites was confirmed by x-ray diffraction (XRD)measurements. A structural analysis of the composites was carried out by scanning electronmicroscopy (SEM) measurements. Electric resistivity measurement as a function oftemperature shows the semiconducting nature of the samples. The dielectric constant (ε′) and losstangent (tanδ) decrease rapidly at lower frequencies and remain constant at higher frequenciesfor all the samples. An AC conductivity measurement was used to discussthe conduction mechanism in all the samples. The ME voltage coefficient(dE/dH)H measured as a function of DC magnetic field gives the maximum ME output of 778 µV cm−1 Oe−1 for 15% of ferrite in the composites.