In this work, the influences of heat generation/absorption and nanofluid volume fraction on the entropy generation and MHD combined convection heat transfer in a porous enclosure filled with a ...Cu–water nanofluid are studied numerically with of partial slip effect. The finite volume technique is utilized to solve the dimensionless equations governing the problem. A comparison with already published studies is conducted, and the data are found to be in an excellent agreement. The minimization of entropy generation and the local heat transfer according to various values of the controlling parameters are reported in detail. The outcome indicates that an augmentation in the heat generation/absorption parameter decreases the Nusselt number. Also, when the volume fraction is raised, the Nusselt number and entropy generation are reduced. The impact of Hartmann number on heat transfer and the Richardson number on the entropy generation and the thermal rendering criteria are also presented and discussed.
Abstract
This study focuses on the magnificent decoration of a painted and gilded wooden panel with signs of fungal biodeterioration caused by
Aspergillus
species in the Mausoleum of Sultan al-Ashraf ...Qaytbay, Cairo, Egypt. Numerous spectroscopic analyses and investigation techniques, including Scanning Electron Microscope Equipped with Energy Dispersive X-ray analysis (SEM–EDX), Fourier Transform Infrared analysis (FTIR), and X-Ray Diffraction (XRD) have been used to study the materials that comprise this painted and gilded wooden panel composition.
Aspergillus niger
,
A. flavus
, and
A. terreus
were recognized as isolated fungi, and their accession numbers are OQ820164, OQ820163, and OQ820160, respectively. The findings showed that the wooden support is of pinewood (
Pinus halepensis
), the white priming layer on top of the wooden support was identified as gypsum, the blue paint layer has been proposed to be Azurite, Au (gold) was the primary composition of the gilding layer, while Pb (lead) was detected in some spots, suggesting the use an alloy of gold with lead, and finally, animal glue was the bonding medium. Based on these findings, mimic samples with identical substrates and structural components have been designed, and the biodeterioration signs by the growing of the three
Aspergillus
species—
A. niger
,
A. flavus
and
A. terreus
were evaluated via SEM and color change. However,
A. niger
was discovered with density growth on surfaces of pinewood, gypsum, and Azurite and with less growth on the gilding layer after 6-month incubation. This contrasts with
A. terreus
and
A. flavus
, which had greater density growth on Azurite and stucco than on pinewood and less growth on the gilding layer. The used analytical methods with detailed analyses revealed the novelty and significant future aspects of the conservation of the painted and gilded wooden panel. Particularly given that this location is used for prayer and is crowded with people five times a day, which increases the accumulation of fungi and negatively affects both the historic Mosque and the worshippers' health.
This research aimed to investigate the properties of bio rayeb milk that results from goats fed on feed supplemented with different concentrations of coriander oil. The study design included a ...control treatment (C) and two coriander oil concentrations, a low level of (0.95%) T1 and a high level of (1.9%) T2. A probiotic starter culture, Direct Vat Set (DVS) of lactobacillus delbrueckii ssp. bulgaricus and streptococcus salivarius ssp. thermophilus in the ratio (1:1) was used to prepare bio rayeb. All treatments were stored at 4 °C for 2 weeks and analyzed on day one and at the end of storage. Results showed that the coagulation time during bio rayeb manufacturing remained consistent at almost 6 h for all batches. However, using a high coriander oil level (1.90%) significantly decreased the apparent viscosity and the content of monounsaturated fatty acids. The DPPH inhibition and the content of monounsaturated fatty acids increased. The electrophoresis chromatogram exhibited a high degree of proteolysis in T2 compared to the control and T1. Microbiologically, yeast, molds, and coliforms were absent in all treatments. Feeding goats on provender supplemented with a low concentration of coriander oil may positively impact the resultant milk's technological and sensorial properties.
In this paper, numerical investigations for magnetohydrodynamic natural convection from two heating systems inside fined triangular enclosures filled with an isotropic porous medium using the ...nanofluids are performed. The two heating modes are represented by two cases, namely, case 1 a triangular enclosure with a heated part at the left wall and including a cold fin at the bottom wall and case 2 in which a cold part at the left wall and a heated fin located at the bottom wall. The copper is considered as nanoparticles and the Darcy model is applied to the porous medium. The triangular physical model is transformed to a rectangular computational model using suitable grid transformations and then the finite-volume method is applied to solve the resulting system. The key parameters in this study are the height, width and locations of the fin, different lengths and locations of the active part, nanoparticles volume fraction, heat generation/absorption parameter, and the Hartmann number. The results revealed that the increase in height of the fins decays the nanofluid flow in case 1, but in case 2, it accelerates the fluid motion. In addition, the increase in width and height of the fin enhances the rate of the heat transfer regardless the heating mode.
Abstract
This article investigates the effect of Ni
2+
content on structural (XRD, XPS), morphological (TEM), and magnetic behaviors of silica magnesium zirconium copper nanoceramics calcined at ...800 °C. The sol–gel route is followed for the silica magnesium zirconium copper/(0.0–0.7) Ni
2+
samples preparation. X-ray photoelectron spectroscopy is employed to analyze the chemical states of elements for the samples. The three representative binding energy magnitudes for O, Ni, and Cu reside at 534, 857, and 979 eV, consecutively. The saturation magnetization constricts with the elevation of Ni
2+
content, while the magnetic hysteresis loop resembles the superparamagnetic attitude. The optical spectra present the possibility of direct and indirect transitions in the prepared nanoceramics. Energy gap (value and type), refractive index, and real and imaginary dielectric constant were extracted. The energy gap approaches 3.75 eV and 3.71 eV for direct and indirect transitions correspondingly with (0.7) Ni
2+
. The antimicrobial and the toxicity performance of all inspected nanocomposites were conducted against pathogenic microbes. The attained results evidenced that SMZC-0.7Ni possesses energetic antimicrobial potential against all targeted microbes. The investigated SMZC-0.7Ni nanocomposite functioned to eradicate frequent waterborne pathogens in wastewater at an appropriate dose (100 mg/L), demonstrating that SMZC can be utilized as a competent disinfectant in the municipal wastewater decontamination process. Inherently, SMZC-0.7Ni can be employed as an excellent nano-weapon against multiple dangerous microorganisms.
A steady laminar two-dimensional magneto-hydrodynamics mixed convection flow in a square inclined cavity filled with Cu–water nanofluid is investigated numerically by using the finite difference ...method. The left and right vertical sidewalls of the cavity are considered adiabatic and move upward, while a partial slip flow condition is imposed on these walls. The horizontal top wall is considered cold and stationary, while a part of the stationary bottom wall is subjected to a uniform heat source and the remaining parts of it are considered adiabatic. An adiabatic obstacle is located in the center of the cavity and an external magnetic field is applied parallel to the horizontal
x
-axis. Parametric studies of the influence of various parameters such as Hartmann number, inclination angle of the cavity, dimensionless heat generation/absorption coefficient, obstacle aspect ratio, dimensionless length and location of the heat source, and solid volume fraction on the fluid flow and heat transfer have been performed. Comparisons with previously published numerical work are performed, and good agreements between the results are observed. It is found that the nanofluid was better than water to enhance the heat transfer when the effect of the magnetic field is weak, while the water is better than the nanofluid when its effect is strong. Moreover, the results indicated that the partial slip has a significant effect on the above-mentioned parameters.
A numerical investigation of entropy generation due to MHD-free convective of Cu–water nanofluid in a porous I-shaped cavity is reported. The cavity is under Darcy law with inclined uniform magnetic ...field. The cavity is cooled from the top and a part of bottom wall subjected to uniform heat flux, while the other parts of walls of the cavity are adiabatic. Mathematical pattern formulated employing the single-phase nanofluid approach in governing equations the problem has been solved by finite difference technique. Prime efforts have been concentrated on the impacts of the pertinent parameters on the fluid flow and heat transfer inside the cavity. Numerical data have been plotted in the form of streamlines, isotherms, and average Nusselt numbers. The results show that the Nu number decreases via increasing the Ha number. It increases when the Ra number is increased. The maximum and minimum values of Nusselt occur at
B
= 0.2 and
B
= 0.8, respectively. Exerting an angle for magnetic flux leads to the improvement in thermal performance for all amount of
B
. The effects of Ha, nanofluid volume fraction, heat source size, location and angle of magnetic field on heat transfer, entropy generation, and thermal performance are completely studied and discussed.
Abstract
In this paper, we present a humidity sensing material based on nanostructured Zn
(1.6 − x)
Na
0.4
Cu
x
TiO
4
spinel to enhance optical and sensitivity performance. Nano-porous of Zn
(1.6 − ...x)
Na
0.4
Cu
x
TiO
4
spinel were synthesized using sol gel reactions and calcined at 700 °C. The nanostructures of Zn
(1.6 − x)
Na
0.4
Cu
x
TiO
4
spinel underwent thorough characterization through multiple techniques. X-ray diffractometry (XRD) coupled with Rietveld refinement using FullProf software, transmission electron microscopy (TEM), Raman Spectroscopy, and optical analysis were employed to assess various aspects of the nanostructures. These techniques were utilized to determine the phase composition, particle size distribution, chemical bonding, and the tunable band gap of the nanostructures. The X-ray diffraction (XRD) analysis of Zn
(1.6 − x)
Na
0.4
Cu
x
TiO
4
samples revealed well-defined and prominent peaks, indicating a highly crystalline cubic spinel structure. The lattice parameter was decreased from 8.4401 to 8.4212 Å with increasing Cu content from 0 to 1.2 mol%. UV–visible diffuse reflectance spectra were employed to investigate the optical characteristics of copper-doped Zn
1.6
Na
0.4
TiO
4
. The applicability of Cu@NaZT spinel nanostructures in humidity sensors was evaluated at ambient conditions. The fabricated sensor was investigated in a wide span of humidity (11–97%). The examined sensor demonstrates a low hysteresis, excellent repeatability, fast response and recovery. The response and recovery times were estimated to be 20 s and 6 s respectively. The highest sensitivity was achieved at 200 Hz. The proposed sensor can be coupled easily with electronic devices as the humidity–impedance relationship is linear.
Abstract
Perovskite oxide materials, specifically MgTiO
3
(MT) and Li-doped MgTiO
3
(MTxLi), were synthesized via a sol–gel method and calcination at 800 °C. This study explores the impact of varying ...Li doping levels (x = 0, 0.01, 0.05, and 0.1) on the crystalline structure and properties of MgTiO
3
. X-ray diffraction analysis revealed a well-defined rhombohedral MgTiO
3
phase. Optical diffuse reflectance measurements provided insights into energy gap values, refractive index, and dielectric constant. Li
+
doping enhanced the electrical properties of MgTiO
3
, with a notable phase transition observed at 50 °C. The study investigated impedance and AC conductivity under varying temperature and frequency conditions (25–120 °C, 4 Hz to 8 MHz). Electrochemical analysis through cyclic voltammetry and electrochemical impedance spectroscopy confirmed highly electrocatalytic properties for MTxLi, particularly when modified onto screen-printed electrodes. This work not only advances the understanding of Li-doped MgTiO
3
nanostructures but also highlights their significant potential for direct electrochemical applications, particularly in the realm of energy storage.
5
′
,
5
′′
-dibromo-o-cresolsulfophthalein (BCP) films were deposited on glass, quartz, and n-Si substrates by using conventional thermal evaporation method. XRD studies showed that the BCP has a ...polycrystalline structure in powder form and a nanocrystalline structure in thin film form. The nanostructure character of BCP films is confirmed by using a high-resolution transmission electron microscope (HRTEM). Thermal stability and phase change were examined by means of thermogravimetric analysis (TGA) and the differential scanning calorimetry (DSC), respectively. Optical absorption studies of BCP films were done in the wavelength range 200-2500 nm. The films showed a direct optical energy gap of 1.89
eV
. Current versus voltage (
I
-
V
) characteristics of Au/BCP/n-Si/Al were studied in darkness and in illumination modes. The device shows photoinduced charge transfer and can be used as a photodiode.
