Cu doped ZnS nanoparticles (Zn1−xCuxS; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction, ...scanning electron microscope, high resolution transmission electron microscope, ultraviolet-visible and photoluminescence spectrometer. The X-ray diffraction and high resolution transmission electron microscope studies show that the size of crystallites is in the range of 2–10nm. XRD study revealed that the samples are composed of cubic phase without doping and at 3mol% Cu doping concentration while at the doping of 5mol% and 10mol% Cu, phase transition from cubic blende to hexagonal phase occurs in ZnS. Photocatalytic activities of ZnS and 3, 5 and 10mol% Cu doped ZnS were evaluated by decolorization of methylene blue in aqueous solution under ultraviolet and visible light irradiation. It was found that the Cu doped ZnS bleaches methylene blue much faster than the undoped ZnS upon its exposure to the visible light as compared to the ultraviolet light. The optimal Cu/Zn ratio was observed to be 3mol% for photocatalytic applications.
•Cu doped ZnS nanoparticles were synthesized by a chemical precipitation method.•ZnS powders calcined at 100°C are in cubic phase and the size of crystallites is in the range of 2–10nm. At higher concentration of Cu (x=0.05 and 0.10) small traces of hexagonal phase are formed.•Photocatalytic activity of Cu doped ZnS significantly higher under visible light as compared to UV light.•Optimal concentration of Cu doped ZnS was observed to be 3mol% for photocatalytic applications.
3, 5 and 10mol% Fe doped CdS nanopowders show strong photocatalytic activity under visible light irradiation, which was observed by measuring the degradation of methylene blue. The optimum Fe/Cd ...ratio was observed to be 3mol% for photocatalytic applications. In contrast, little degradation was observed for the pure CdS powder. Display omitted
► Fe doped CdS nanoparticles were synthesized by a chemical precipitation method. ► With increased the Fe doping concentration, the position of the Raman bands shifted towards higher wavenumbers and their intensities decreased drastically. ► Optical measurements indicated that the absorption edge shifted towards the longer wavelength side in Fe doped CdS nanoparticles. ► Fe doped CdS nanoparticles show excellent Photocatalytic activity under visible light irradiation. ► Optimum concentration of Fe doped CdS was observed to be 3mol% for photocatalytic applications.
Fe doped CdS nanoparticles (Cd1−xFexS; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman and UV–vis spectrometer. The XRD and TEM measurements show that the size of crystallites is in the range of 2–10nm. With increased the Fe doping concentration, the position of the Raman bands shifted towards higher wavenumbers and their intensities decreased drastically. Optical measurements indicated that the absorption band edge shifted towards longer wavelength upon Fe doping. Direct allowed band gap of undoped and Fe doped CdS nanoparticles measured by UV–vis spectrometer were 2.3 and 2.2eV at 100°C, respectively. Photocatalytic activities of CdS and Fe doped CdS were evaluated by irradiating the solution of methylene blue (MB) and sample under visible light. It was found that Fe doped CdS bleaches MB much faster than undoped CdS upon its exposure to the visible light. The optimum Fe/Cd ratio was observed to be 3mol% for photocatalytic applications. In contrast, little degradation was observed for the pure CdS powder.
Heterocycles are important structural components in pharmacophores that are currently being used to treat several diseases. Among the various heterocyclic scaffolds, nitrogen and sulfur containing ...spiroheterocycles are essential structural motifs that constitute diverse biodynamic agents. In the last two decades, a paradigm shift has occurred in the synthesis of spirothiazolidin‐4‐ones by replacing conventional and multi‐step synthesis with green protocols, that use novel organo and nanocatalysts. In this review, literature on spirothiazolidin‐4‐ones from years 2000–2021 has been summarized into groups of different synthetic strategies and their potential biological activities.
In this review, new developments in the synthetic strategy and biological profile of spirothiazolidin‐4‐ones have been reviewed from years 2000 to 2021. Literature on spirothiazolidin‐4‐ones for past 20 years has been summarized and categorized.
In the present article, a brief introduction about multiferroic composites is provided. Recent advancement in the field of multiferroic composites is discussed by classifying these in bulk ...composites, thick & thin films and other heterostructures. Research findings of some renowned work are summarized, considering new emerging materials, new methods of synthesis and latest characterization techniques. Further recent applications are discussed along with future challenges of the field.
•This paper uses building structural attributes such as shapes of buildings, relative compactness(RC), glazing area(GA), roof area(RA), surface area(SA), wall area(WA), orientation(OR), overall ...height(OH) and glazing area distribution(GAD) for prediction of heating and cooling load.•The paper explores the data set and features to get insights with feature correlation, mutual information their association strengths etc and their relation with heating and cooling load.•The paper proposes novel group of methods based on emerging machine learning method extreme learning machine(ELM) which has shallows architecture.•The paper proposes novel method based on ELM variant online sequential extreme learning machine(OSELM) for heating and cooling load prediction in online and adaptive environment. This model also helps when data is trained in chunk by chunk fashion.•The paper demonstrates several models based on combination of learning mode, activation function and features sets and compare their results with existing work extensively.
In the present day environment, smart buildings require optimization of energy consumption through monitoring, consumption prediction and making policy decisions accordingly. Attributes related to building design and structure play a vital role in heating load(HL) and cooling load(CL) of the building which directly affects the energy performance of the buildings. For prediction of HL and CL, emerging machine learning approaches can help in improving accuracy and efficiency in real time. This paper provides improvements in energy load assessment of the buildings. It is the first is the in-depth study and analysis of design and structural attributes and their correlation with HL and CL, the novel methods based on ELM and its variants online sequential ELM(OSELM) to predict HL and CL. This study also proposes OSELM based online/real-time prediction when data is coming in stream The total 24 models have been developed including 12 models based on ELM and 12 models based on OSELM with different feature sets and activation functions. Models have been compared on the basis of accuracy, computational performance and efficiency with few existing models. The experimental results show that the proposed models learn better and outperform other popular machine learning approaches such as the artificial neural network(ANNs), support vector machine(SVM), radial basis function network(RBFN), random forest(RF) and existing work in the energy and building domain.
Ag-doped ZnO nanoparticles (Zn
1−x
Ag
x
O; where x = 0.00–0.05) were synthesized by chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron ...microscope (SEM), transmission electron microscope (TEM) and UV–Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and the measurements show that the size of crystallites is in the range of 10–40 nm. Optical measurements indicated a red shift in the absorption band edge after Ag doping. The band gap values of as prepared undoped and doped with silver samples were found to decrease with increase in temperature from 300 to 800 °C. Photocatalytic activities of ZnO and Ag doped ZnO were evaluated by irradiating the sample solution to ultraviolet light by taking methylene blue as organic dye. The experiment demonstrated that the photo-degradation efficiency of 1 mol% Ag-doped ZnO was significantly higher than that of undoped and 2–5 mol% Ag doped ZnO under ultraviolet light irradiation.
This work studies the effect on dielectric properties of lead zirconium titanate (Pb1.1Zr0.4Ti0.6O3 PZT) thick films under UV light illumination (wavelength =325 nm) for the realization of tunable ...capacitors. A modified sol–gel technique is utilized for the growth of polycrystalline PZT thick films on nickel substrate. The PZT films are deposited on Ni, and three different temperatures (450, 550, and 650 °C) are selected for annealing the samples in air atmosphere. Dielectric studies are performed on the optimized films, under varying intensities of UV radiation. Enhanced dielectric constant values are observed under UV illumination for the PZT films annealed at 550 and 650 °C due to generation of photocarriers and induced oxygen vacancies. An appreciable change in dielectric constant of about 75% at 1 MHz frequency is seen for the PZT film fabricated at higher annealing temperature (650 ºC) under UV illumination (intensity = 12 mW cm−2). The obtained results are encouraging for the utilization of thick PZT films in tunable capacitors.
Variation of dielectric constant of a Pb1.1Zr0.4Ti0.6O3 (PZT) thick film with frequency (in the presence and the absence of UV radiation) at an annealing temperature of 650 °C (inset: dielectric measurement setup under UV illumination).
Undoped and zinc-doped TiO
2
nanoparticles (Ti
1−x
Zn
x
O
2
where x = 0.00–0.10) were synthesized by a sol–gel method. The synthesized products were characterized by X-ray diffraction (XRD), scanning ...electron microscope (SEM), transmission electron microscope (TEM) and UV–VIS spectrometer. XRD pattern confirmed the tetragonal structure of synthesized samples. Average grain size was determined from X-ray line broadening using the Debye–Scherrer relation. The crystallite size was varied from 10 to 40 nm as the calcination temperature was increased from 350 to 800 °C. The incorporation of 3–5 mol% Zn
2+
in place of the Ti
4+
provoked a slight decrease in the size of nanocrystals as compared to undoped TiO
2
. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology with a diameter of about 10–30 nm and length of several nanometers, which is in agreement with XRD results. Optical absorption measurements indicated a blue shift in the absorption band edge upon 3–5 mol% zinc doping. Direct allowed band gap of undoped and Zn-doped TiO
2
nanoparticles measured by UV–VIS spectrometer were 2.95 and 3.00 eV at 550 °C, respectively.
•Eulerian two-fluid modeling is explored for flow boiling through the horizontal tubes.•Modeling of wall heat flux partition and mass transfer discussed.•Thermal behavior of the horizontal tube wall ...is analyzed for various operating conditions.•Pressure drop, wall temperature, velocities and volume fractions are predicted.•High circumferential wall temperature gradient occurs at the liquid-vapor contact region.
The flow boiling process is common in many industrial applications as well as direct steam generation (DSG) in the receiver of parabolic trough solar collector (PTSC) and linear Fresnel reflector (LFR) systems. The objective of the present work is to investigate the flow boiling heat transfer through the horizontal tube numerically for the various potential applications in the DSG process in the solar collectors. The thermo-hydrodynamic study of flow boiling through the horizontal tube is presented through the two-fluid model (TFM) approach using computational fluid dynamics (CFD) software, ANSYS Fluent 19.0. Three dimensional (3-D), steady-state numerical simulations are performed by applying the Eulerian multiphase critical heat flux (CHF) boiling model. The flow conditions considered are similar as in the DSG in the solar collectors. The simulations are performed for 12 m length of the horizontal stainless-steel tube having inner and outer diameter 70 mm and 50 mm respectively with the mass flow rates ranging from 0.3 kg/s to 0.6 kg/s, operating pressures 30 to 100 bar, and wall heat flux 17.74 kW/m2. The variations in the pressure drop, vapor volume fraction, circumferential wall temperature, contours of vapor volume fraction, velocities have been predicted under the considered operating conditions. The pressure drop in the tube for the various operating conditions considered is in the range of 115 Pa to 426 Pa and the pressure drop is observed higher at the lower operating pressure. The pressure drops are observed as 222.4 Pa, 145 Pa, and 115.2 Pa respectively for the operating pressure of 30 bar, 60 bar, and 100 bar at the mass flow rate (MFR) of 0.3 kg/s. The large thermal gradient in the tube wall is observed in the circumferential direction at the liquid-vapor interface. The minimum and maximum value of ∆T (∆T = Tmax – Tmin) around the circumference are observed as 28.3 K and 77.1 K respectively for the given operating conditions. The circumferential temperature difference decreases with an increase in the operating pressure. The value of ∆T around the circumference is observed for the MFR of 0.3 kg/s as 77.1 K, 58.1 K, and 45.7 K respectively for operating pressure of 30 bar, 60 bar, and 100 bar. The contours of tube wall temperature at various axial positions have been plotted. The vapor volume fractions for the MFR of 0.3 kg/s are 0.6, 0.51, and 0.45 respectively for operating pressures of 30 bar, 60 bar, and 100 bar. The vapor volume fraction (VVF) decreases at the outlet of the tube as the MFR or operating pressure increases. The mixture velocity and the relative velocity between the phases have been predicted. The present study concluded that higher operating pressure is more suitable in terms of pressure loss and the thermal gradient. The presented numerical model is useful for the thermal performance analysis of DSG in the PTSC as well as the LFR system and other industrial applications having flow boiling through the horizontal tubes.
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