Experimental design and analysis of advanced three phase converter for PV application with WCO-P&O MPPT controller

Photovoltaic (PV)-based power generation systems are becoming increasingly popular as a due to its high performance and cleanliness. Several factors influence the performance of a PV system, including shadowing effects. PV systems employ MPPT methodologies to obtain the power from PV array. Conventional MPPTs works well under normal conditions when there is no shadow effects or partial shading. The presence of partial shading affects the system performance and generates several power peaks. This complicates the process of finding out of the global peak (GMPP) with improved tracking efficiency and reduced settling time including conversion efficiency. This work proposes three hybrid MPPT techniques: Water Cycle Optimisation-Perturb and Observe (WCO-PO), Artificial Neural Network Supported Adaptable Stepped-Scaled Perturb and Observe (ANN-ASSPO), Grey Wolf Optimisation-Modified Fast Terminal Sliding Mode Controller (GWO-MFTSMC), and two conventional MPPT techniques WCO and P&O have been implemented. The proposed system utilizes interleaved boost converter with three phase. The performances of proposed hybrid MPPTs strategies were compared in terms of output voltage, output current and extracted power. The comparison also includes conversion efficiency and average settling time. To analyse the performances, four different cases have been used to test the efficacy of hybrid MPPTs under changing climatic conditions. The MATLAB/Simulink tool has been used to analyze the PV system performances. In the three hybrid MPPT techniques, WCO-PO has performed better when compared to other two hybrid MPPTs in terms of conversion efficiency (99.56%) and settling time (1.4 m).

A quad DC source switched three-phase multilevel DC-link inverter topology

The concept of an isolated DC source cascaded multilevel inverter finds good solutions for generating quality output voltage for low-medium power applications. It shapes the output voltage from three levels into a number of steps closer to a sinusoidal shape using small DC sources or batteries. Several advantages have been sighted like lower voltage stress and bearing noise, and lesser THD. However, a common issue in the MLIs is the total components required which increase with the rise in voltage levels. This paper proposes a three-phase MLI design having several isolated quad voltage source modules including an H-Bridge inverter. The design suggested claims reduced switching components for current conduction paths showing improved output quality. The operational features of the suggested MLI have been analyzed using Matlab/Simulink software, furthermore, an experimental module is constructed for demonstrating the effectiveness of the simulated results.

Biogenic Synthesis, Characterization, and Photocatalytic Evaluation of Pristine and Graphene-Loaded Zn50Mg50O Nanocomposites for Organic Dyes Removal

Algal biomass synthesised nanocomposites have a higher surface area and reusability advantages. This study aimed to synthesise and characterise ZnMgO and silica-supported graphene with ZnMgO (G-ZnMgO) nanocomposites from Kappaphycusalvarezii and evaluate their potential in the application of photocatalysis to remove Rhodamine-B (RhB) and methylene blue (MB) dyes from their aqueous medium by maximising the percentage removal using response surface methodology (RSM) modelling. Nanocomposites were synthesised and characterised by biogenic and instrumental (Powder X-ray diffraction (P-XRD), electron microscopic analysis (SEM and TEM), Fourier transform infrared spectroscopy (FTIR), Energy dispersive analysis of X-rays (EDAX). and UV-visible diffuse reflectance spectroscopy (UV-DRS)) methods, respectively; modelling predicted the optimal conditions to be photocatalyst dosage and contact time of 1 g/L and 90 min, respectively, to obtain maximum MB dye removal of 80% using G-ZnMgO. The results showed the best fit between experimental and RSM predicted values. Thus, the obtained results conclude that the algal biomass synthesised nanocomposites were found to be one of the potential photocatalysts for the removal of RhB and MB dyes from their aqueous solution.

Ecofriendly biopolymers and composites: Preparation and their applications in water-treatment

Over the past few decades, the term polymer has been repeatedly used in several industries for their immense characteristics in different applications. Polymers and their composites which were prepared from chemical monomer sources turned out to be potentially harmful to the environment due to their tedious degradation process. Biopolymers are natural substitutes for synthetic polymers which can be efficiently extricated from natural sources. They are predominantly available as polymeric units as well as monomeric units that are linked covalently. These environment-friendly biopolymers and their composites can be categorized based on their numerous sources, different methods of preparation and their potential form of usage. They were found to be biocompatible and biodegradable which make them exceptionally useful in environment based applications, mainly in the process of water treatment, both potable and wastewater. Further, the biopolymer and biopolymer composites easily fit into different parts of the treatment process by acting as filtration media, adsorbents, coagulants and as flocculants. The primary focus of this review is to provide a comprehensive information of biopolymers and biopolymer composites from synthesis to their usefulness for their productive application in water treatment processes. On the whole, it can be substantiated that the biopolymers were identified to play a notable adversary to the synthetic polymers in treating waters with an indispensable need for an elaborative study in the production of the biopolymers.

Use of chicken feather and eggshell to synthesize a novel magnetized activated carbon for sorption of heavy metal ions

Keeping environment and sustainability concept in view with preparation of new sorbents, two waste by-products from the poultry industry, i.e. feather and eggshell, were used for synthesis of a new magnetic activated carbon for sorption of heavy metal ions. Using response surface methodology based central composite design (RSM-CCD) technique, chicken feather and acid-digested eggshell were used as precursor and activation material, respectively, for the synthesis of the herein studied activated carbon (eggshell activated chicken feather carbon; ESCFC). The prepared activated carbon was magnetized for easy separation from water media, and iron oxide magnetized ESCFC (IOM-ESCFC) was comprehensively examined for removing some heavy metallic ions (Pb²⁺, Cd²⁺, Cu²⁺, Zn²⁺, and Ni²⁺) from water. The maximum mono-layer sorption capacities and the highness of sorption speed, along with thermodynamic studies, demonstrated that IOM-ESCFC can be regarded as a potential adsorbent against heavy metal ions from waters and wastewaters.

Efficient mercury removal from wastewater by pistachio wood wastes-derived activated carbon prepared by chemical activation using a novel activating agent

Ammonium nitrate (NH₄NO₃) with explosive characteristics at high temperatures was used as a novel activating reagent to prepare a surface-engineered activated carbon derived from pistachio wood wastes (PWAC). PWAC was characterized and compared with commercial activated carbon (CAC) by textural and morphological properties, surface chemistry, crystal structure, and surface elemental composition. The results indicated that the optimal conditions of PWAC preparation to obtain the highest mercury adsorption capacity were pyrolysis temperature (800 °C), pyrolysis time (2 h), and impregnation ratio (5%). PWAC was of highly regular-shaped and well-developed pores and possessed a large surface area (1448 m²/g) and high total pore volume (0.901 cm³/g). The batch experiments indicated that the adsorption process of Hg(II) was strongly dependent on the solution pH and reached fast equilibrium at approximately 30 min. PWAC (202 mg/g) exhibited a significantly higher maximum adsorption capacity than commercial activated carbon (66.5 mg/g). Adsorbent-adsorbate dispersion interaction plays a major role in the adsorption mechanism, compared to the minor role played by pore filling and reduction mechanism. Overall, ammonium nitrate can be considered a newer activating reagent to prepare promising and low-cost PWAC for effectively Hg(II) removal from water media.

Adsorption property of Br-PADAP-impregnated multiwall carbon nanotubes towards uranium and its performance in the selective separation and determination of uranium in different environmental samples

A newer efficient U(VI) ion adsorbent was synthesized by impregnating Br-PADAP [2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol] onto multiwall carbon nanotubes (MWCNTs). The effects of various operation conditions on uranium adsorption (i.e., pH contact time, temperature, and initial uranium concentration) were systematically evaluated using batch experiments. The results indicated that the uranium adsorption on modified MWNCTs (5.571 × 10^-3g/mg × min) reached faster equilibrium than that on pristine MWNCTs (4.832 × 10^-3g/mg × min), reflecting the involvement of appropriate functional groups of Br-PADAP on the chelating ion-exchange mechanism of U(VI) adsorption. Modified MWNCTs (83.4mg/g) exhibited significantly higher maximum Langmuir adsorption capacity than pristine MWNCTs (15.1mg/g). Approximately 99% of uranium adsorbed onto modified MWNCTs can be desorbed by 2.5mL of 1M HNO₃ solution. Therefore, Br-PADAP-modified MWNCTs can server as a promising adsorbent for efficient uranium adsorption applications in water treatment. Subsequently, the proposed solid-phase extraction (using a mini-column packed with Br-PADAP/MWCNT) was successfully utilized for analysing trace uranium levels by the ICP-AES method in different environmental samples with a pre-concentration factor of 300-fold. The coexistence of other ions demonstrated an insignificant interference on the separative pre-concentration of uranium. the detection limit was recognized as 0.14μg/L, and the relative standard deviation was approximately 3.3% (n = 7).

Bacteriocin Produced from Lactobacillus plantarum ATM11: Kinetic and Thermodynamic Studies

In the present study, the effect of heat treatment on the activity of bacteriocin from Lactobacillus plantarum ATM11 was studied. The kinetic and thermodynamic parameters were calculated for the thermal inactivation of the bacteriocin over a time–temperature combinations in the range of 30, 45, 60 and 90 min and 60, 65, 70, 75 and 80 °C. Understanding the thermal inactivation of biopreservatives in a food matrix is essential to allow their proper utilization in food industry, enabling the reduction of heating times and optimization of heating temperature. The results indicate the different thermal stabilities with k-values between 0.0159 and 0.0225 min−1. D-values decreased with increase in temperature, indicating faster inactivation of the bacteriocin at higher temperatures. These results suggest that bacteriocin is relatively heat stable with a z-value of 22.85 °C.

Batch adsorption studies for chromium removal

The adsorption of hexavalent chromium (Cr (VI)) on pongamia (Pongamia pinnata) leaf powder was investigated in the present study. Crude pongamia leaf powder (CPLP) and nitric acid treated pongamia leaf powder (APLP) were used as adsorbents. CPLP did not show remarkable adsorption efficiency but APLP had good adsorption capacity and adsorption removal efficiency. The parameters studied included the contact time, initial solute concentration and pH. The optimum pH for removal of chromium was found to be 2 for both CPLP and APLP. The best contact time for maximum chromium adsorption was 165 minutes for CPLP and APLP. CPLP and APLP showed good adsorption capacity and adsorption removal efficiency at an initial chromium concentration of 5 mg/L. The adsorption was found to follow Langmuir and Freundlich isotherms for CPLP and APLP but they showed good curve fit for Freundlich isotherm.

Quantitative DNCB epicutaneous sensitization in leprosy patients and controls

Status of non-specific cell mediated immunity in 49 leprosy patients classified according to Ridley & Jopling scale and 16 non leprous controls was studied using epicutaneous sensitization with DNCB and quantitatively grading the degree of sensitization with DNCB and quantitatively grading the degree of sensitization and Mx. test with 1 TU PPD. The effect of dapsone administration on CMI responses was also observed. There was no gross depression of CMI responses as made out by epicutaneous sensitization to DNCB but quantitative grading of responses revealed a subtle depression of CMI responses progressively increasing from II to LL end of spectrum. Mx. testing with 1 Tu PPD did not appear to be a good parameter to study the CMI status. Dapsone administration did not alter the CMI responses.

Leucocyte migration inhibition test in leprosy patients across the spectrum of leprosy

The leucocyte migration inhibition test (LMIT) using Dharmendra's antigen was performed in 21 cases of leprosy classified according to Ridley Jopling Scale (1966). The degree of migration correlated well with the classification as expected thus confirming the immunological validity of Ridley-Jopling classification.

Efficacy of co-trimoxazole in Donovanosis. A preliminary report

Co-trimoxazole (Septrin, Wellcome) was prescribed in a dose of two tablets twice daily for the treatment of 10 patients with Donovanosis. All the patients responded well to this treatment, and the ulcers healed completely within 10 days in eight patients and within 14 days in the remaining two. Ten days' treatment with 40 tablets of co-trimoxazole is suggested as sufficient to treat Donovanosis. No adverse reactions were noted in any patient.