In the chemical, pharmaceutical, and petroleum industries, Shell and U-Tube Heat Exchangers (STHX) were extensively utilized. Baffles must be positioned at the right distance and angle to increase ...the heat exchangers' capacity to convey heat and, as a result, lower pressure in the shell. The rate of heat transfer in an STHX has been improved, and pressure drop has been reduced using a variety of models. But those methods are not provided satisfactory pressure drop reduction. In the proposed model, an optimal Unilateral Ladder-Type Helical Baffles (ULHB) design and intelligent performance prediction system based U-tube heat exchanger was designed to reduce the pressure drop as well as predict the heat exchanger performance. The shell and tubes were made up of steel and copper material, respectively. A baffle was placed above tubes to barrier the flow of cold water. The design of the baffle was accomplished by using Chimp Optimization Algorithm (ChOA) and is motivated by the hunting behaviour of chimpanzees. After designing the exchanger, its fluid analysis was verified, and the parameter values of the heat exchanger were collected to create a dataset. Based on that data, the intelligent performance prediction-system was designed. The controlling system analysed the given data to predict the performance of the heat exchanger. The suggested model has a pressure drop of 55 Pa, a heat transfer coefficient of 411
U,
and 86% accuracy for the thermal performance prediction process. The proposed model provides better performance by improving heat transfer efficiency and significantly reduces pressure drop.
Adansonia digitata L.(Malvaceae) is commonly known as baobab tree native to Africa.Baobab is a multi-purpose tree which offers protection and provides food,clothing and medicine as well as raw ...material for many useful items.The fruit pulp,seeds,leaves,flowers.roots,and bark of baobab are edible and they have been studied by scientists for their useful properties.The fruit pulp have very high vitamin C.calcium,phosphorus,carbohydrates,fibers,potassium,proteins and lipids content,which can be used in seasoning as an appetizer and also make juices.Seeds contain appreciable quantities of phosphorus,magnesium,zinc,sodium,iron,manganese,whereas they have high levels of lysine,thiamine,calcium and iron.Baobab has numerous biological properties including antimicrobial,anti-malarial,diarrhoea,anaemia,asthma,antiviral,anti-oxidant and anti-inflammatory activities amongst others.Phytochemical investigation revealed the presence of flavonoids.phytosterols.amino acids,fatty acids,vitamins and minerals.The review summarizes the information on various aspects of traditional information,taxonomic description,medicinal properties and importantly nutritional value.
Because of their high stability, innocuous behaviour, outstanding electric
properties and multi-functionality, lead-free double perovskites have
emerged as a promising alternative to lead-based ...perovskites. We present
here the structural, microstructural, dielectric and electrical properties
of a newly synthesized double perovskite Nd2FeTiO6 (NFTO). The Rietveld
refinement of its X-ray diffraction pattern revealed a monoclinic structure
with space group P121/c1. The oxide exhibits a temperature-independent
dielectric constant and di-electric loss at low temperatures (below 200 ?C)
making the compound a suitable candidate for fabricating thermally stable
capacitors. The AC conductivity was investigated using the Jonscher?s
universal power law, and it was inferred that the conduction process is
caused by the Correlated BarrierHopping (CBH) mechanism. Furthermore,
frequency dependent AC conductivity also revealed the NTCR nature of the
NFTO compound.
Transition metal ions (Ag+, Cu2+, and Ni2+) doped and undoped TiO2 nanoparticles (NPs) were synthesized via cost effective sol-gel method with 1.0 wt% dopant concentration. The microstructure and ...chemical compositions of these NPs were examined using various techniques such as x-ray diffractometry, field emission scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared and absorption and photoluminescence (PL) spectroscopy. The average size of the NPs is in the range of 10–20 nm and lattice spacing is 0.36 nm corresponding (101) plane. The absorption and photoluminescence (PL)-excitation spectra of metal-doped TiO2 NPs are shifted to the longer wavelength region, which indicates reduced bandgap than the bare TiO2 NPs. The absorption and PL spectra of methylene blue (MB) in the presence of undoped and metal ions doped TiO2 NPs show dramatic changes upon UV-irradiation. The absolute absorption intensity reduced entirely and the solution of MB became colorless in the presence of UV irradiation. The PL of the degraded dye exhibits a new band in the shorter wavelength region, which has a multi-exponential decay function and an increased average PL lifetime. Among all the samples, Cu2+ ions-doped TiO2 NPs shows the superior photocatalytic activity for the degradation of dye and followed pseudo-first-order kinetics.
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•Transition metal ions doped and undoped TiO2 NPs of 10–20 nm with a lattice spacing of 0.36 nm (101 plane) was developed.•Doping of metal ions in TiO2 reduces the bandgap and recombination rate.•Cu2+ doped TiO2 NPs have the highest photocatalytic rate in the degradation of dye.•PL and PL-lifetime of the degraded dye (MB) confirm the presence of new species.•NPs can be used as catalysts for industrial and environmental applications.
Titanium dioxide (TiO2) nanoparticles (NPs) were prepared by the sol-gel method with titanium isopropoxide as a precursor at different annealing temperatures. The analysed X-ray diffraction (XRD) ...patterns, Raman and Fourier transform infrared spectra characteristics demonstrated the structural transformation from amorphous to anatase and further to rutile phase while increasing annealing temperature. In addition, a mixed phase of TiO2 NPs is formed, which consists of both the phases. The absorption and photoluminescence (PL) spectra of mixed and rutile phases are shifted towards longer wavelength region. Furthermore, the photocatalytic performance of the different type of TiO2 NPs was examined through the degradation of a dye, rhodamine B (RhB) under UV radiation, and by measuring changes in absorption and PL spectra. The anatase phase structure shows higher photocatalytic activity than the rutile phase. However, the mix phase has the highest photocatalytic activity among all the structures, which degraded RhB entirely with a faster rate. On the other hand, the rutile phase is unable to take part in this process. Thus, the mix phase of TiO2 NPs is highly useful for industrial and environmental applications.
Three different phases, namely anatase, mixed and rutile phases of TiO2 nanoparticles (NPs) were developed with varying temperatures from 400 to 900 °C and confirmed using various characterization ...techniques. The XRD analysis of TiO2 NPs in temperature range of 290 to 77 K with no significant changes predict the thermally stable NPs. Photoinduced carrier dynamics of TiO2 NPs were investigated by the temperature dependence (TD) photoluminescence (PL) and TD time-resolved PL (TRPL) decays. With varying temperatures from 290 to 77 K, the anatase phase exhibits an additional and dominant 530 nm PL band. However, the mixed and rutile phases show three well-resolved PL bands, including 420 nm, 530 nm and near-infrared (NIR) bands at 820 nm at a lower temperature. Again, 530 nm band dominated for mixed-phase.
In contrast, for the rutile phase, the 820 nm band dominated at <100 K. The PL lifetime of the 420 nm band is nearly a single exponential for all the phases. And is also true for the 530 and 820 nm PL bands, but bi-exponential for ≤100 K. Both the PL and TRPL results predict the presence of trap states in TiO2 NPs for anatase and rutile phases. The PL is originated due to donor-acceptor recombination, whereas oxygen vacancies served as donor and hydroxyl groups serve as accepter sites. The NIR band is attributed to the trapped electrons in rutile TiO2, which recombine with free holes and intrinsic defects. Also, the trapped electrons were generated in one of two ways: direct trapping or trap-to-trap hopping. The carrier dynamic in NPs depends on the trap states as the photoexcited carriers transfer into surface sites which competes with non-radiative and radiative recombinations during the relaxation process. Thus, the findings show that the trap states in TiO2 can significantly influence TiO2 photocatalytic activity when exposed to appropriate light.
Patent protection emerged as one of the most challenging barriers to the access to medicines, medical equipment, and vaccines as well for the treatment and containment of Covid‐19 when it became a ...pandemic. The severe scarcity of vaccines and pharmaceutical products were weakening the fight against Covid‐19, and endeavor to contain the recurrence of pandemic waves while mutation of the SARS‐CoV‐2 was also on the full swing. Therefore, India and South Africa jointly proposed for patent waiver at WTO in October 2020 to effectively deal with the short‐supply of medicines, medical equipment, vaccines and high price concern related to these products. After 20 months of consultation and negotiations with major stakeholders, the WTO came up with decision on patent waiver in 12th Ministerial Conference (12th MC). The time taken to reach to the decision in the pandemic situation and the narrow scope of the decision is a serious concern for the entire world to deal effectively with Covid‐19 and its variants. This paper attempts to analyse the patent waiver in the context of the agreement on Trade Related Aspects of Intellectual Property Rights (TRIPS). It discusses patent barriers, alternative measures and needs for equitable access to vaccines and pharmaceuticals amidst the pandemic. Paper applies the qualitative methodology of research mainly content analysis method in the framework of contextualisation, decontextualisation, and recontextualisation. Results show that suspending certain provisions of the TRIPS required for the production of vaccines and medicines would prove a crucial tool for economies to return to its pre‐Covid‐19 era. Paper concludes that, patent waiver can be one of the most important tool to fight the Covid‐19 (as WHO has not yet declared the end of pandemic) and will pave the way to deal with any such unknown future pandemic effectively.
•Co2+ doped ZnO and bare ZnO nanoparticles with wurtzite structure were developed.•PL spectrum of ZnO NPs changes from dual bands to single band with dopants.•The bandgap and defect states of ZnO NPs ...reduce with dopants.•The average PL lifetime of Co-ZnO NPs decreases from 14.05 ns (pure ZnO NPs) to 4.66 ns.•20% Co2+ doped ZnO NPs shows superior photocatalytic activity for dye degradation.
Cobalt-doped and undoped zinc oxide (ZnO) nanoparticles (NPs) with different dopant concentrations were synthesized via the sol-gel method. The structural, morphological, and optical properties of the synthesized NPs were investigated using various techniques. The NPs exhibit a wurtzite structure with an average crystallite size of 20–34 nm. Change in photoluminescence (PL) spectra from dual to single band with dopants suggested decreasing surface state contribution. The PL lifetime of the 430 nm band is too short (< 10 ps), where it is multi-exponential and significantly large for the 550 nm band with a major contribution of 0.3–1.0 ns and a minor contribution of 7–9 ns and 119–126 ns. The photocatalytic performance of NPs was examined by decomposing a Congo red dye under dark, white (LED) light and UV irradiation. Among all the doped NPs, 20% Co2+ doped ZnO shows superior photocatalytic activity for dye degradation with a faster reaction rate constant.
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