An experimental investigation on the nanofluids in a cavity under natural convection with and without the rotary magnetic field.

This experimental study involves the use of two distinct categories of nanofluids, namely ferromagnetic and non-magnetic, within a square cavity that facilitates natural convection. There are five distinct concentrations associated with each nanofluid. Natural convection arises as a consequence of the thermal gradient between the opposing surfaces of the copper cavity, which has a thickness of 18 gauge. The purpose of utilizing the constructed electro-magnet assembly is to investigate the impact of the rotational magnetic field on the process of heat transfer. The manipulation of magnetic strength can be achieved by regulating the magnetic power and direct current (DC) power. The manipulation of the electromagnet's spin can also be regulated. In the context of a rotational magnetic field, it is seen that the magnetic flux undergoes a transition from a positive value to an almost identical negative value throughout a full rotation. The optimal heat transfer performance is observed at a nanoparticle concentration of 0.1% by volume (φ) for both nanofluids. In the absence of a rotating magnetic field, the ferromagnetic nanofluid exhibited superior performance. When the Rayleigh number (Ra) is one order smaller than the critical Rayleigh number value, the heat transfer performance is often superior with nanofluid compared to demineralized water.

Kinetics of carbon dioxide absorption in aqueous blend of 1-(2-aminoethyl) piperazine using a stirred cell reactor.

Carbon capture utilization and storage (CCUS), the technology for decarbonizing carbon dioxide (CO2) from greenhouse gas emitters such as steel, cement, oil, gas, petrochemicals, chemicals, and fertilizers, has a critical role to play in the world to achieve industrial net zero targets by 2050. CO2 can be separated from industrial exhaust gases/flue gases using amine-based solvents utilizing the post-combustion CO2 Capture process. One most crucial solvent characterization for this application is the kinetics of CO2 absorption. This work identifies aqueous 1-(2-aminoethyl) piperazine (AEPZ) as a potential candidate for CO2 capture solvent. The kinetics of absorption of CO2 in aqueous AEPZ is studied using stirred cell reactor. The experiments are performed at temperatures ranging from 303 to 333 K with weight fractions of AEPZ in an aqueous solution ranging from 0.1 to 0.4. One of the critical parameters of the kinetic study is Henry's constant which is determined experimentally using another stirred cell reactor at a similar temperature and pressure range. The experimental data shows that the overall rate constant is Kov = 2.52987 × 10-4 mol/m2s-kPa for 0.1 wt fr. of AEPZ at 313 K with an initial CO2 partial pressure of 10 kPa. The temperature dependency relation of the second-order reaction rate constant, [Formula: see text] is found to be [Formula: see text] using the Arrhenius equation. The activation energy of 0.3 wt fr. AEPZ is found to be 42.42 kJ/mol. In addition, the density and viscosity of the aqueous solvent are determined at a wide range of temperatures. The diffusivity of CO2 and physical solubility used in the model development has also been determined. The kinetic parameters obtained from this study are helpful in the process design of CO2 capture in a regenerative process with a blended solvent with AEPZ.

Experimental and Computational Investigation upon Combustion Characteristics of Liquid Fuel in a Novel Combustor with Hybrid Swirl and Recirculation Bowl.

In the present study, a novel hybrid swirl combustor is designed to reduce the size and complexity of a conventional gas turbine combustor. In this combustor, a dual-swirl pattern is adopted by providing the central vane swirler (45° vane angle) and circumferential tangential injection scheme to achieve higher recirculation of heat and combustion products inside the combustor. Numerical and experimental studies are carried out to understand the flow patterns and combustion characteristics in this high mass-heat interacting environment. Initially, computational studies were carried out to find the optimum geometry for greater recirculation and interaction among the reacting species inside the combustor. Liquid fuel (kerosene) is sprayed into the combustor for two thermal inputs of 25 and 50 kW. Three cases were studied to analyze the effect of bowl recirculation and tangential air inputs in addition to the swirlers. The hybrid swirl, formed by the counter-flow pattern, helps in achieving low and uniform temperature throughout and assists in flame anchoring. The tangential air flow provides a push to the combustion products from the downstream to the central recirculation zone of the combustor. The combined effect of central and tangential swirlers helps in attaining a more distributed combustion. The CO and NO emissions reduced with the use of hybrid swirl.

Water footprint comparison of a naphtha-fired combined cycle power plant and a coal-fired steam power plant.

The vulnerability of the power generation industries vulnerability to the availability of water is widespread and growing. In this regard, water footprint (WF) is one method to assess this challenge. The present study conducts the WF of a naphtha-fired combined cycle power plant (CCPP) and a coal-fired steam power plant (CSPP). For carrying out WF, it is prudent to look after water consumption during operations and the supply chain stages. Hence, in this regard, two methods have been adopted to investigate the WF of both power plants. The first method deals with the water balance mass diagram (direct WF), and the second method deals with the water supply chain (indirect WF). Evaporation loss appears to be a significant contributing factor to the direct WF. On the other hand, operational WF seems to be an essential contributing factor to indirect WF. Furthermore, the result also shows that specific water consumption in CSPP is 3.54 m3/h, whereas, in CCPP, it is 0.9 m3/h. Finally, some methods have also been suggested to reduce WF in both power plants.

Brassica nigra essential oil: In-vitro and in-silico antibacterial efficacy against plant pathogenic and nitrifying bacteria.

The present study was aimed to examine the antibacterial potential of Brassica nigra essential oil (BNEO) against Ralstonia solanacearum, causal agent of bacterial wilt and Nitrosomonas sp., the nitrifying bacteria. In poisoned food assay, BNEO showed 100% growth inhibition of R. solancearum at ≥ 125 µg mL-1. Revalidation of findings by volatile assay employing inverted Petri plate technique exhibited 100% bacterial growth inhibition caused by vapors of BNEO, even at 50 µg mL-1 concentration. In the broth microdilution assay, the BNEO exhibited significant antibacterial activity only at higher concentrations (>500 µg mL-1). At 500 µg mL-1, BNEO showed 80% bacterial growth inhibition over control, which was at par with that of streptomycin (5 µg mL-1). In resazurin microtitre-plate assay, the maximum concentration of BNEO, at which color change occurred was 512 µg mL-1 (T9), and thus 512 µg mL-1 was concluded as the minimum inhibitory concentration (MIC). BNEO effectively inhibited the activity of Nitrosomonas spp. with 30-65% nitrification inhibition at the dose of 400 mkg-1 of Urea-N. Homology modeled protein targets assisted computational tool-based novel analysis helped to understand that the antibacterial potency of BNEO is due to preferable binding efficiency of allyl isothiocyanate (AITC), the major active ingredient of BNEO.

Deciphering the Behavioral Response of Meloidogyne incognita and Fusarium oxysporum Toward Mustard Essential Oil.

Environmental concerns related to synthetic pesticides and the emphasis on the adoption of an integrated pest management concept as a cardinal principle have strengthened the focus of global research and development on botanical pesticides. A scientific understanding of the mode of action of biomolecules over a range of pests is key to the successful development of biopesticides. The present investigation focuses on the in silico protein-ligand interactions of allyl isothiocyanate (AITC), a major constituent of black mustard (Brassica nigra) essential oil (MEO) against two pests, namely, Meloidogyne incognita (Mi) and Fusarium oxysporum f. sp. lycopersici (Fol), that cause severe yield losses in agricultural crops, especially in vegetables. The in vitro bioassay results of MEO against Mi exhibited an exposure time dependent on the lethal concentration causing 50% mortality (LC50) values of 47.7, 30.3, and 20.4 µg ml-1 at 24, 48, and 72 h of exposure, respectively. The study revealed short-term nematostatic activity at lower concentrations, with nematicidal activity at higher concentrations upon prolonged exposure. Black mustard essential oil displayed excellent in vitro Fol mycelial growth inhibition, with an effective concentration to cause 50% inhibition (EC50) value of 6.42 µg ml-1. In order to decipher the mechanism of action of MEO, its major component, AITC (87.6%), which was identified by gas chromatography-mass spectrometry (GC-MS), was subjected to in silico docking and simulation studies against seven and eight putative target proteins of Mi and Fol, respectively. Allyl isothiocyanate exhibited the highest binding affinity with the binding sites of acetyl cholinesterase (AChE), followed by odorant response gene-1 (ODR1) and neuropeptide G-protein coupled receptor (nGPCR) in Mi, suggesting the possible suppression of neurotransmission and chemosensing functions. Among the target proteins of Fol, AITC was the most effective protein in blocking chitin synthase (CS), followed by 2,3-dihydroxy benzoic acid decarboxylase (6m53) and trypsinase (1try), thus inferring these as the principal molecular targets of fungal growth. Taken together, the study establishes the potential of MEO as a novel biopesticide lead, which will be utilized further to manage the Mi-Fol disease complex.

Process optimization for the supercritical carbondioxide extraction of lycopene from ripe grapefruit (Citrus paradisi) endocarp.

In this study, an underutilized citrus family fruit named grapefruit was explored for the extraction of lycopene using supercritical carbon dioxide (CO2) extraction technique. An experimental design was developed using response surface methodology to investigate the effect of supercritical carbon dioxide (CO2) operating parameter viz., pressure, temperature, CO2 flow rate, and extraction time on the extraction yield of lycopene yield from grapefruit. A total of 30 sets of experiments were conducted with six central points. The statistical model indicated that extraction pressure and extraction time individually, and their interaction, significantly affected the lycopene yield. The central composite design showed that the polynomial regression models developed were in agreement with the experimental results, with R2 of 0.9885. The optimum conditions for extraction of lycopene from grapefruit were 305 bar pressure, 35 g/min CO2 flow rate, 135 min of extraction time, and 70 °C temperature.

A Comprehensive in vitro and in silico Analysis of Nematicidal Action of Essential Oils.

Nematicidal potential of essential oils (EOs) has been widely reported. Terpenoids present in most of the essential oils have been reported responsible for their bioactivity though very less is known about their modes of action. In the present study, an in vitro screening of nine Eos, namely, Citrus sinensis (OEO), Myrtus communis (MTEO), Eucalyptus citriodora (CEO), Melaleuca alternifolia (TEO), Acorus calamus (AEO), Commiphora myrrha (MREO), Cymbopogon nardus (CNEO), Artemisia absinthium (WEO), and Pogostemon cablin (PEO) against Meloidogyne incognita revealed OEO, CNEO, and TEO as most effective with LC50 39.37, 43.22, and 76.28 µg ml-1 respectively. EOs had varying compositions of mono- and sesquiterpenes determined by gas chromatography-mass spectrometry (GC-MS) analysis. The in silico molecular interactions screening of major EO constituents and the seven selected target proteins of the nematode indicated highest binding affinity of geraniol-ODR1 (odorant response gene 1) complex (ΔG = -36.9 kcal mol-1), due to extensive H-bonding, hydrophobic and π-alkyl interactions. The relative binding affinity followed the order: geraniol-ODR1 > ß-terpineol-ODR1 > citronellal-ODR1 > l-limonene-ODR1 > γ-terpinene-ODR1. Taken together, the cumulative in vitro and computational bioefficacy analysis related to the chemoprofiles of EOs provides useful leads on harnessing the potential of EOs as bionematicides. The insight on biochemical ligand-target protein interactions described in the present work will be helpful in logical selection of biomolecules and essential oils for development of practically viable bionematicidal products.

Supercritical fluid extraction of ß-carotene from ripe bitter melon pericarp.

Study ascertained the recovery of ß-carotene from enzyme-treated (enzyme load of 167 U/g) pericarp of ripe bitter melon using supercritical fluid extraction (SFE) technique. Effect of different pressure (ranged from 150-450 bar), carbon dioxide (CO2) flow rates (ranged from 15 to 55 ml/min), temperatures (from 50 to 90 °C), and extraction periods (from 45-225 minutes) were observed on the extraction efficiency of ß-carotene. Results showed that extraction pressure (X1) among extraction parameters had the most significant (p < 0.05) effect on extraction efficiency of the ß-carotene followed by allowed extraction time (X4), CO2 flow rate (X2) and the temperature of the extraction (X3). The maximum yield of 90.12% of ß-carotene from lyophilized enzymatic pretreated ripe bitter melon pericarp was achieved at the pressure of approx. 390 bar, flow rate of 35 mL/min, temperature at 70 °C and extraction time of 190 min, respectively. Based on the accelerated storage study the 70% retention shelf life of the ß-carotene into extract was estimated up to 2.27 months at 10 °C and up to 3.21 months at 5 °C.

A biorefinery for valorization of industrial waste-water and flue gas by microalgae for waste mitigation, carbon-dioxide sequestration and algal biomass production.

Massive industrialization all over the globe is the main cause for the generation of huge quantity of wastes such as flue gas and wastewaters. Mindless release of these hazardous wastes into the environment is threatening the health and survival of the mankind. Judicious use of these wastes for microalgal biomass cultivation is recognized as a plausible approach for the creation of a renewable and sustainable process chain for biofuel production. This study was designed to cultivate microalgae utilizing the organic and inorganic nutrients from the industrial wastewater (IWW) and coal-fired flue gas (FG) for simultaneous waste bio-remediation and biomass production for biorefinery application in closed photobioreactors. The two microalgae, Chlorella sp. and Chlorococcum sp. were cultivated in industrial wastewater where varying concentrations of coal-fired FG from 1 to 10% CO2, volume/volume percent (v/v) was supplied to stimulate the mixotrophic growth. Performance of the two microalgae was evaluated in terms of nutrient removal (ammonium, nitrate, phosphate and COD), CO2 fixation, total lipid and carbohydrate content obtained in the integrated mode of process development. The IWW with flue gas (5% CO2 (v/v)) resulted in maximum growth and CO2 fixation. The highest biomass growth (1.52 g L-1) and CO2 fixation (187.65 mg L-1 d-1) of Chlorella sp. with nutrient removal of >70% was observed by 5th day of batch cultivation. Nearly 90% removal of nitrogen resulted in nutrient limitation condition that steered the accumulation of lipid (17-34%) and carbohydrate (21.5-23.1%) in Chlorella and Chlorococcum sp. An overall 1.7 fold improvement in biomass was observed in this process integration compared with control culture. The present study presents a green process for waste remediation, CO2 fixation and production of biomass rich in lipid & carbohydrate content for the development of a green microalgal biorefinery.

Performance evaluation of a green process for microalgal CO2 sequestration in closed photobioreactor using flue gas generated in-situ.

In the present study, carbon-dioxide capture from in situ generated flue gas was carried out using Chlorella sp. in bubble column photobioreactors to develop a cost effective process for concomitant carbon sequestration and biomass production. Firstly, a comparative analysis of CO2 sequestration with varying concentrations of CO2 in air-CO2 and air-flue gas mixtures was performed. Chlorella sp. was found to be tolerant to 5% CO2 concentration. Subsequently, inhibitory effect of pure flue gas was minimized using various strategies like use of high initial cell density and photobioreactors in series. The final biofixation efficiency was improved by 54% using the adopted strategies. Further, sequestered microalgal biomass was analyzed for various biochemical constituents for their use in food, feed or biofuel applications.