Microwave Irradiation Technique Research Articles

Ultrafast Microwave-Assisted Synthesis of Porous NiCo Layered Double Hydroxide Nanospheres for High-Performance Supercapacitors

Currently, new clean energy storage technology must be effective, affordable, and ecologically friendly so as to meet the diverse and sustainable needs of the energy supply. In this work, NiCo-LDH containing intercalated EG was successfully prepared within 210 s using an ultrafast microwave radiation technique. Subsequently, a series of characterization and systematic electrochemical tests were conducted to analyze the composition, structure, and energy storage mechanism of the NiCo-LDH material. The Ni:Co ratio of 5:5 results in the highest capacitance value of 2156 F/g at 1 A/g and an outstanding rate performance of 86.8% capacity retention rate at 10 A/g. The results demonstrated that the unique porous structure of NiCo-LDH and large layer spacing were conducive to more electrochemical reactions. Additionally, an electrochemical test was carried out on the NiCo-LDH as a hybrid supercapacitor electrode material, with NiCo-LDH-5:5 serving as the positive electrode and activated carbon as the negative electrode, the asymmetric supercapacitor can achieve a maximum energy density of 82.5 Wh kg−1 and power density of 8000 W kg−1. The NiCo-LDH-5:5//AC hybrid supercapacitors own 81.5% cycle stability and 100% coulombic efficiency after 6000 cycles at 10 A/g.

MICROWAVE AIDED SYNTHESIS OF ZINC OXIDE NANOCERAMICS: A POTENT BIOACTIVE AGENTS WITH THERAPEUTIC CHARACTERS

Nanoparticles have been inexhaustibly utilized in Nanochemistry cohere with Bio-Technology to upgrade the immobilization and movement of catalysts in pharmaceutical nanoengineering for conveyance of helpful specialists in incessant illness diagnostics and in sensors.Herein communication we report microwave irradiation technique implemented for the preparation of novel Zinc oxide nanoparticles with beneficial bio-efficacy wherein the method employed has the advantages of producing small particle size metal oxide with high purity owing to short reaction time. We successfully synthesized and characterized two Zinc oxide based Cs2 doped ZnO2 and Li2 doped ZnO2 nanoparticles and were subjected to in vitro free radical scavenging assay wherein all the particles could scavenge DPPH and Nitric oxide radicals with less IC50 value over the positive control. Microbicidal properties of nanoparticles were proved by its effectiveness against both Gram positive and Gram negative bacteria tested besides its action against Candida albicans. Both nanoparticles synthesized showed a prominent inhibition of erythrocyte lysis by PhospholipaseA2 in a concentration dependent manner indicating better anti-inflammatory agent with possibility of preventing cancer. In this study we demonstrate by shell less CAM assay that synthesized nanoparticles could inhibit in vivo angiogenesis which would otherwise under abnormal conditions causes the acceleration of several inflammatory diseases in spite of its role in normal growth and wound healing process. Inhibition of such process is the promising methodology to hinder the progression of diseases. Present characteristic features make use of ZnO2 based doped nanoparticles to be a possible approach as a therapeutic molecule with favourable biological performance.

Enhanced electrochemical energy storage devices utilizing a one-dimensional (1D) α-MnO2 nanocomposite encased in onion-like carbon

AbstractThis work describes the fabrication of a novel one-dimensional (1D) α-MnO2 nanorods encased in onion-like carbon (or) carbon nano-onions (OLC) via microwave irradiation techniques employing electrolytic manganese dioxide (EMD), which is especially beneficial for rapid ion and electron transfer, and great structural stability. The composite of α-MnO2 and OLC demonstrates exceptional performance as an electrode across various electrochemical energy storage systems, including zinc-ion batteries (ZIB), sodium-ion batteries (SIB), and supercapacitors (SC) than the pristine α-MnO2. In SIB systems, the composite exhibits a specific capacity of 266 mAh g−1 at initial cycle with 50% capacity retention over 500 cycles, whereas the pristine electrode delivers only 39% capacity retention. The rapid yet controlled charge transfer kinetics facilitated by OLC addition in the α-MnO2 matrix outperforms as the ZIB cathode with an excellent specific capacity of 476 mAh g−1 with 100% capacity retention, while the pristine sample exhibits 77.5% capacity retention. As a SC electrode, the α-MnO2/OLC composite exhibits better electrochemical properties such as rectangular behavior, increased specific capacitance (792 F g−1), excellent capacity retention at high current densities, and others. The higher surface area that could be offered by the OLC to the α-MnO2 matrix facilitates the improved electrochemistry in the pristine sample and this kind of modification can be a viable solution to overcome the limitations of α-MnO2 for electrochemical energy storage applications. It is important to note that the performance outputs of α-MnO2/OLC composite are far better than the regular carbon (graphite, graphene) in α-MnO2 electrodes. Further, OLC provided with high surface area and ordered morphology can play the role of conductivity booster, structural stabilizer, and electrochemical active material in all the energy storage applications which may give a significant research attention in near future.

Application of a Surface Waveguide in Microwave Drying Units of the Agribusiness Industry

In the last two decades, the electromagnetic field of the microwave range has been successfully introduced into various branches of the agribusiness industry as one of the most promising and advanced technologies for drying manufactured products. In this regard, the article proposes a new microwave irradiation technique for drying various objects based on a surface waveguide’s properties. The paper analyses the main links that make up the surface waveguide as a microwave irradiation system and shows the ways of their implementation. The article describes the advantages of applying a vibratory device for exciting a surface wave, using a re-emitting antenna array, and operating a single conductor with a dielectric coating as a surface waveguide. Such advantages make it possible to introduce microwave drying units with the required distribution of electromagnetic field energy along the irradiated material, small dimensions, high drying quality, and low price.

Modified refractance window drying of jamun pulp (Syzygium cumini) based on innovative infrared and microwave radiation techniques

The present study aimed to dry jamun pulp (Syzygium cumini) by combining infrared and microwave energy in refractance window drying. The two different sets of experiments were planned using the hybrid design. The three independent parameters considered for the infrared refractance window drying (IR-RWD) included infrared lamp power (30–70% of the 1000 W lamp), pulp layer thickness (1–3 mm), and distance between the lamp and pulp layer (3.42–6.60 cm). In microwave refractance window drying (MW-RWD), the independent variables were oven-set microwave power (150–450 W), pulp layer thickness (1–3 mm), and power density (1–2.5 W g−1). The optimum conditions in IR-RWD were 40.75% infrared lamp power, 1 mm pulp layer thickness, and 3.42 cm distance between the lamp and pulp layer, resulting in dry jamun flakes with 17.93 ± 0.32 mg GAE g−1 total phenolic content, 4.37 ± 0.13 color change, 8.90 ± 0.22 mg QE g−1 total flavonoid content, and 179.05 ± 2.17 C3G mg/100g total anthocyanin content. In the case of MW-RWD, the optimum conditions were 212.4 W oven-set microwave power, 3 mm pulp layer thickness, and 2.2 W g−1 power density, resulting in 15.68 ± 0.28 mg GAE g−1 total phenolic content, 8.47 ± 0.25 color change, 8.20 ± 0.21 mg QE g−1 total flavonoid content, and 149.72 ± 1.81 C3G mg/100g total anthocyanin content. The Page model can precisely describe the jamun pulp drying behavior of IR-RWD and MW-RWD. Also, apparent moisture diffusivity was estimated in both drying methods. IR-RWD was found to be a better drying method than MW-RWD in terms of drying rates and the quality parameters of the dry jamun flakes.

Ni-MOF Based Flexible Solid-State Supercapacitors in Aqueous and Non-Aqueous Electrolytes

Supercapacitors are high power density devices which acts a bridge between the batteries and conventional capacitors. Several emerging materials like Metal Organic Frameworks (MOFs) have been developed as electrode material for energy storage. MOFs are highly porous materials containing metal centers and organic moieties called ligands [1].They are widely employed for energy storage applications owing to their structural and morphological tunability [2]. In our recent research work, Ni MOF is synthesized using microwave assisted solvothermal technique at different temperature and metal to ligand ratios. Ni MOF is synthesized by varying metal to ligand ratio (M:L) as 1:1, 2:1, 3:1 and 4:1. The solution is heated by microwave irradiation technique [3] from room temperature to 150, 165, 180 and 200 °C to obtain light green colored samples. It is interesting to observe that different synthesis parameters lead to different morphologies thereby resulting in improved performance of Ni MOF. The structural and electrochemical characterizations reveal “why does a particular morphology exhibits better charge storage capacity?” The three electrode configuration experiments were conducted in aqueous electrolyte to evaluate the charge storage capacity. The results show that globules (∼1360 F g-1) perform better than nanoflower (∼850 F g-1), flakes (∼650 F g-1) and plates (∼450 F g-1) [4] respectively in 2M KOH at 0.5 A g-1. The reason is attributed to the low solution resistance (R sol) for globules, reduced charge transfer resistance (R ct) and the global and local n values of CPE.The synthesized material (Ni MOF) will be used as positive electrode material for flexible asymmetric supercapacitor. Recently, flexible state supercapacitors (FSSCs) have gained popularity due to their formability, flexibility and high energy density. Here, the objective is to increase energy density and power density by extending the operating potential window of the device. Hence, the aqueous electrolyte is substituted with PVDF based ionogels (ionic liquid gel polymer) to impart flexibility, bendability and high power density to FSSC. It is observed that the potential window improved remarkably from ~0.6 V (aqueous electrolytes) to ~5 V (ionic liquid). The reason is attributed to the absence of water, results in thermodynamic stability of the electrolyte. Also, the ionic liquid based FSSCs are non-flammable, non-toxic, thermally stable. In order to improve the conductivity and charge storage capacity some additives are incorporated in the gel polymer matrix. Herein, certain polar solvents are added to enhance the conductivity due to their high dielectric constant giving rise to faster ionic dissociation. MOF based flexible supercapacitors are fabricated and tested for their energy and power densities in conjunction with electrochemical and structural characteristics .

Single-stage microwave-irradiated activated carbon from corncob for ammonia nitrogen removal: Batch, attraction mechanism and regeneration studies

The existence of ammonia nitrogen (NH3-N) in water reservoirs contribute to the poor quality of water, thus affecting aquatic life and human. Therefore, the goal of this study was to treat NH3-N from wastewater using activated carbon derived from corncob (CCAC). The CCAC was produced through a single-stage microwave irradiation technique where carbon dioxide (CO2) was utilized for the gasification effect. The CCAC demonstrated a mesoporous surface area measuring 645.97 m2/g, accompanied by a total pore volume of 0.41 cm3/g. Furthermore, the average pore diameter was determined to be 2.74 nm. The equilibrium study revealed that NH3-N uptakes and NH3-N percentage removal increased (9.11–59.49 mg/g) and declined (91.10–59.49 %), respectively, when NH3-N initial concentration increased from 10 to 100 mg/L. At a solution temperature of 30 °C, the greatest adsorption capacity for NH3-N was observed, reaching 59.49 mg/g. Similarly, at a pH of 4, the adsorption capacity peaked at 71.46 mg/g. Adsorption of NH3-N onto CCAC obeyed the Langmuir isotherm model and pseudo-first order (PFO) kinetic model. It was determined that the maximum monolayer coverage, Qm was 78.05 mg/g. The investigation of the mechanism indicated that film diffusion is the rate-determining step in the adsorption process. In the thermodynamic section, the parameters of ΔH°, ΔS°, ΔG°, and Ea were computed to be −1.70 kJ/mol (exothermic in nature), 0.05 kJ/mol.K (elevated randomness at the solid-liquid interface), −18.22 kJ/mol (spontaneous) and 1.89 kJ/mol, respectively. The surface of CCAC was occupied with different functional groups namely nitro compound, aromatic compound, and phenol. These functional groups formed hydrogen bonding with NH3-N, thus aiding NH3-N removal from wastewater. In the regeneration study, CCAC can withstand up to 3 cycles before its yield dropped to 33.21 % and its adsorption capacity dropped to 10.15 %.

Synthesis by Microwave Irradiation, Molecular Structural Analysis and Trypanocidal Activity of Novel Pyrazole-tetrahydropyrimidine Derivatives.

A series of new eight 2-(1-aryl-3-methyl-1H-pyrazol-4-yl)-1,4,5,6-tetrahydropyrimidines 1(a-h) were synthesized by microwave irradiation technique. In vitro phenotypic screening was performed to evaluate the effect of these compounds on intracellular amastigotes forms of Trypanosoma cruzi</i>, the etiological agent of Chagas disease. Compounds 1(a-h) were synthesized from pyrazole-carbonitriles 2(a-h) employing microwave irradiation (50W) for 10-20 minutes. Physicochemical properties were calculated using OSIRIS DataWarrior. The toxic effect on mammalian cells (Vero Cells) and the trypanocidal activity against Trypanosoma cruzi</i> (Dm28c-Luc) were also evaluated. Compounds 1(a-h) were obtained in 24-94% yields. They were completely characterized by Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) and High-Resolution Mass Spectrometry (HRMS) analyses. The derivatives showed low trypanocidal activity, with IC50 ranging from 47.16 to > 100 μM, with lower activity than benznidazole (1.93 μM) used as reference drug. The attractive features of this synthetic methodology are mild conditions, short reaction time, and low power. All derivatives showed low toxicity in mammalian cells, good oral bioavailability, and did not violate Lipinski´s rule of 5.

Microwave-assisted of new derivatives of polyimine conjugated polymer based on Schiff base: synthesis, characterization, and photo-physical properties as a photoluminescent materials

The condensation of pyrrole-2,5-dicarbaldehyde (1) with 5-(2-amino-4-phenylthiazol-5-yl)-4-phenylthiazol-2-amine (2) and/or 5-(4-Amino-phenyl)-4-phenylthiazol-2-amine (3) gave new poly(Z)-N-((5-(iminomethyl)-1H-pyrrol-2-yl)methylene)-5-(2-((E)-(5-(iminomethyl)-I-pyrrol-2-yl)methyleneamino)-4-phenylthiazol-5-yl)-4-phenylthiaol-2-amine (P1) and/or poly(E)-N-((5-(iminomethyl)-1H-pyrrol-2-yl)methylene)-5-(4-((E)-(5-(iminomethyl)-1H-pyrrol-2-yl)methyleneamino)phenyl)-4-phenylthiaol-2-amine (P2) as a novel conjugated polymer by microwave irradiation and traditional heating.. It is evident that the microwave irradiation technique quickly raised the molecular weight of polyimines. In addition to quantifying the molecular weight of the resultant polyimines. All the polyimines were characterized using FTIR, XRD, H1NMR, TGA, and DSC. The optical characteristics of polyimine derivatives were investigated using a UV–Vis spectrophotometer. The absorption spectra showed a main absorption band around 372 nm for polyimine (P1) and 381 nm for polyimine (P2). The optical energy was calculated and found to be 2.49 and 2.68 eV. The photoluminescence of the polyimine derivatives was measured and analyzed by spectrofluorometer and Laser photoluminescence experiment and the emission color was studied using CIE graphs. The fluorescence spectra showed an emission peak at 548 nm for polyimine (P1) with yellow green color in CIE graph, while for polyimine (P2) the emission band was located at 440.5 nm with blue color in CIE graph. Photoluminescence quantum yield PLQY was measured for the polyimine P1 and P2 in both liquid and Solid states and indicated the AIE behavior of the polyimines. TD-DFT simulations were applied to the polyimine derivatives where the structures were geometrically optimized and the spectroscopic characterizations were evaluated.

Green biosynthesis of stable silver nanoparticles bound with macaranga indica plant extracts for the purification of drinking water

Plant-assisted green biosynthesis of silver nanoparticles (NPs) has become the most powerful technique to prepare stable NPs. Macaranga indica is a medicinal plant widely available in the western ghats. It has verities of medical properties like antibacterial, antioxidant, antidiabetic, cytotoxicity, and antidysentery and is commonly used in the traditional medicine system. This plant also contains polyphenols, flavonoids, and other plant constituents. Here, in this study, macaranga indicia leaf extract is used as a capping agent for the synthesis of silver NPs by using the microwave irradiation technique. Synthesized NPs are characterized by using Uv-Vis Spectra, XRD, EDX, FESEM, and FTIR. Interpretation of characterization data reveals that synthesized NPs are in a spherical shape, monodispersed, and have particles the size of ~15-20 nm. These bicapped silver NPs have shown potential thermotolerant bacterial inhibition activity and are also efficient in methylene blue dye removal and hence can be used in the purification process of drinking water at its source.

Effect of stepped microwave irradiation to develop carbon nanotubes on carbon fiber for enhanced performance

In the present research, carbon nanotubes were grown on carbon fiber (CF) by continuous and stepped microwave irradiation techniques. Ferrocene was used as a catalyst, and toluene was used as a microwave absorber to grow the CNTs on CF. Continuous microwave irradiation (CMI) was carried out at 720 W microwave power for 25 s. The stepped microwave irradiation (SMI) was performed at 720 W for 25 s, followed no irradiation for 15 s and further irradiation of 5 s. It was observed that SMI resulted in a dense forest of CNT without any agglomeration and damage to the CF surface compared to CMI. The ID/IG ratio of the CNTs grown with CMI and SMI was observed to be 1.03 and 0.99, respectively. This confirms the presence of denser CNT forest after SMI. The SMI showed improved wettability of the CF with respect to epoxy resin compared to CMI due to an 18% decline in contact angle. The ultimate tensile strength (UTS) of the resulting CFRP composite increased by 28% with SMI grown CNTs compared to CMI grown CNTs. The enhanced UTS is due to improved interfacial bonding between the CF layers due to denser CNTs obtained after SMI.

Bioderived cellulose fibre-guar gum grafted poly (N, N′-dimethylacrylamide) polymer network for controlled release of metformin hydrochloride

An interpenetrating polymer network (IPN) of areca cellulose and guar gum grafted with poly (N, N′-dimethylacrylamide) was made by microwave irradiation technique. N, N-methylenebisacrylamide (MBA) was used as the crosslinking agent. The network polymer was characterised using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Powder X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The chemical interaction between the drug and the polymer was studied using Differential Scanning Calorimetry (DSC). The swelling of the gel was measured under different pH conditions and the swelling parameters were evaluated. The gel was loaded with an anti-diabetic drug, Metformin Hydrochloride, and the in vitro drug release was studied in gastric and intestinal conditions. The results indicated complete release of the drug in 6 h under pH 1.2 and in 10 h under pH 7.4. The kinetic analysis of release data indicated the drug release to follow Higuchi's model. The release exponent “n” of Korsmeyer-Peppas model was found to be >0.45 indicating the drug diffusion to be a non-Fickian process.

Microwave assisted synthesis, characterization and bioactivity evaluation of a cobalt (II) complex with a novel Schiff base ligand derived from phenylacetyl urea and salicylaldehyde

The study comprehensively focusses on the synthesis and characterization of a novel Co(II) metal complex formed by the condensation of phenylacetyl urea and salicylaldehyde with Thiocyanate ion using an eco-friendly microwave irradiation technique, which resulted in a higher yield. The molecular formula and geometry of the complex were deduced through an array of techniques including UV–Vis spectra, FT-IR, Far IR, Cyclic voltammetry, thermal analysis, and Powder XRD. The molar conductance data revealed a non-electrolyte [1:0] type complex. Notably, the FT – IR spectral peaks obtained at 3388 cm−1, 2914 cm−1,1622 cm−1 shows that Schiff base and Thiocyanate ions were coordinated to the metal ion in a monodentate manner. Furthermore, electronic spectra values confirmed a pseudo tetrahedral geometry for the complex. Intriguingly, our study also encompassed an exploration of the biological activities of both the Schiff base ligand and the Co(II) metal complex. By subjecting them to antimicrobial assays against various microorganisms, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeurginosa, Staphlococcus aureus, Bacillus cereus, Aspergillus favus, Aspergillus niger, Aspergillus sojae, Aspergillus oryzae, and Candida albicans. It was found that the complex exhibited moderate activity against bacteria and remarkably enhanced activity against fungi when compared to the free Schiff base ligand. Additionally, we investigated the DPPH free radical scavenging activity of the complex and the ligand, unveiling that the Co(II) complex demonstrated significantly higher antioxidant activity in comparison to the ligand. These results highlight the potential of the synthesized Co(II) complex as a promising candidate for biomedical applications. Overall, this study not only sheds light on the synthesis and characterization of the Co(II) metal complex with a novel Schiff base ligand but also unravels its distinct biological activities, indicating its potential significance in antimicrobial and antioxidant applications.

Utilization and evaluation of catalytic activity of hydroxyapatite on the synthesis of some corosolic acid amide

Hydroxyapatite was employed as a catalyst for the synthesis of 17C-corosolic amide by the condensation of 17C-corosolic acid chloride and phenyl hydrazide under solvent-free microwave irradiation technique. In this condensation the obtained yield is more than 87%. Within this condensation the catalytic activity and reusability of this hydroxy apatite was investigated on the basis of percentage of yield. The prepared amide was characterized by their analytical and spectroscopic data.

Design and synthesis of oxazepine derivatives from sulfonamide Schiff bases as antimicrobial and antioxidant agents with low cytotoxicity and hemolytic prospective

The eco-friendly sonication and microwave irradiation techniques were used for the straight forward synthesis of the Schiff base platform from sulfathiazole. Herein, Schiff bases were developed and converted to oxazepane derivatives. Compounds were tested for their antimicrobial, antioxidant, in vivo cytotoxicity activity. Moreover, density functional theory (DFT) and molecular docking studies were also carried out to explore the structural prpoperties and interaction of compounds with the receptor molecules. In vitro antimicrobial activity was determined against Gram-positive and Gram-negative strains via microdilution technique, which showed that the synthesized derivatives exhibit significant antimicrobial activity. Furthermore, in vivo cytotoxicity activity of the compounds were carried out via intravenous injection in rats. The results were compared with negative controls and it was observed that most of the synthesized compounds displayed excellent antimicrobial activity and low toxicity in comparison to references and negative controls, respectively. Hemolysis test was carried out for bioactive compounds, and results showed higher hemolysis values of the Schiff bases than the correponding oxazepines and lower hemolytic effects. The free radical inhibittion and antioxidant activity was carried out by using 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) and ferric reducing antioxidant power (FRAP) methods which suggested that the free radical scavenging activity increases with the presence of hydroxyl group. The Spectral measurements fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and high resolution electrospray ionization mass spectrometry (HRESIMS) confirmed the structure of the compounds.

Microwave Irradiation Technique: A Green Chemistry Approach for Dissolution Enhancement of Ritonavir

This research was focused on improvement of aqueous solubility of Ritonavir (RIT), Antiretroviral (ART) drug by preparing solid dispersion (SD) through solvent methodology and microwave irradiation (MWI) technique as a green chemistry approach. In MWI different batches of SD were formulated by 32 factorial approach with time of exposure (X1) and power of radiation (X2) as variable quantity and dissolution rate as response (Y1). β-CD was used as hydrophilic carriers. Drug carrier magnitude relation of 1:1 resolve by phase solubility analysis and SD were assessed for drug content, percentage dissolution rate studies, FTIR, XRD, DSC and SEM analysis. The FTIR, XRD, DSC and SEM studies exhibited no interaction between RIT and excipient. In Physical mixture (PM) it shows less intensity and disappearance of sharp peaks while in SD indicates the conversion of crystalline state of RIT to amorphous state that discovered the dissolution enhancing, so the SD prepared by MWI proved to be a promising approach to increasing the dissolving rate of BCS class II drug RIT. Hence, from the all analysis studies, it absolutely was evident that factorial batch F2 was the higher. F2 coded batch (RIT: β-CD within the magnitude relation of 1:1 with time of exposure (4 min) and power of radiation (450 Watt), shows 06 folds increase i.e. 58% compared with drug discharged inside 60 min to plane RIT and SD i.e. 9 % only and 47 % respectively.

Study of Photophysical Properties of Thiol-capped CdS Quantum Dots Doped with Gold Nanoparticles.

In this study, CdS quantum dots (QDs) capped with benzyl mercaptan (thiol) were prepared by microwave irradiation technique. The shape, size, morphology, and spectral properties of thiol-capped CdS QDs were characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-vis absorption, and photoluminescence (PL) spectrometry. The photophysical properties of synthesized thiol-capped CdS QDs in the presence of different amounts of gold nanoparticles (AuNPs) have been investigated, exhibiting strong PL quenching. The amount of fluorescence quenching was found to be dependent on the concentration of metal nanoparticles. A Stern-Volmer kinetics model was used to analyze the observed quenching mechanism as a function of the quencher (AuNPs) concentration. The Stern-Volmer plot along with the absorption spectra of thiol-capped CdS QDs in the absence and presence of AuNPs suggest the dynamic (collision) nature of quenching and rule out the possibility of static quenching. The energy transfers from QDs to Au NPs, and hence the quenching of QDs emissions provides new insight into designing novel optical-based materials and the development of FRET-based bionanosensors and phototherapeutic applications.

Schiff Base Synthesis with a New Reliable Method and Investigation of Their Inhibition Effects on Glutathione S‐Transferase and Cholinesterase Enzymes

AbstractThe principle purpose of this study is to synthesize some Schiff base derivatives with a new microwave irradiation technique and investigate their enzyme inhibition effects. Related Schiff base compounds (1 a–1 h) were synthesized from 4‐fluoro aniline and some substituted benzaldehyde derivatives (3 a–3 h). The chemical structures of Schiff bases were elucidated by various spectroscopic methods (1H NMR, 13C NMR). The inhibitory effects of the synthesized compounds against acetylcholinesterase, butyrylcholinesterase and glutathione S‐transferase were investigated. The in vitro enzyme study determined the best enzyme inhibitors for AChE, BChE, and GST enzymes as 3 h, 3 b, and 3 e compounds, respectively. The results were compared with the standard drugs tacrine for cholinesterase and ethacrynic acid for GST enzymes. Molecular docking results demonstrated the low binding energy values between −5.8 kcal/mol and −8.7 kcal/mol with hydrogen bonding, hydrophilic, and hydrophobic interactions at the active catalytic sites of the enzymes.

Enhancement of Valsartan Oral Bioavailability by Preparing a Microwave-Irradiated Inclusion Complex with Sulfobutyl Etherβ-Cyclodextrin Using a Central Composite Face Design for Optimising Process Parameters.

The purpose of the study is to investigate the influence of sulfobutyl ether β-cyclodextrin (SBE7-β-CD) on the bioavailability of valsartan. Phase solubility investigations showed an AL type curve. The estimated apparent stability constant for valsartan SBE7-β-CD is 427 ± 0.32M-1. Inclusion complexes of valsartan SBE7-β-CD in equal molar ratio were prepared by microwave irradiation technique. The process parameters were optimised with a central composite face design. Response surface graphs and contour plots showed how process factors affected drug content. The inclusion complexes prepared by optimising process variables are characterised. The DSC and X-ray diffraction confirm the formation of inclusion complexes and the drug's transition from a crystalline to an amorphous state. FTIR suggests hydrogen bonding between valsartan and SBE7-β-CD. SEM showed changes in drug morphology and shape. The dissolution rate of the prepared SBE7-β-CD complex using microwave irradiation was 2.85 times that of pure valsartan. The inclusion complex was formulated into tablet dosage forms F1 to F4. Furthermore, oral bioavailability studies in rats with tablet formulation F3 were carried out and compared to the marketed Diovan® tablet as a reference standard. The F3 tablet formulation exhibited significantly higher values of AUC0-∞ and Cmax than the reference. Finally, the microwave-irradiated valsartan SBE7-β-CD inclusion complex converted into tablet dosage form may be a promising approach to increasing valsartan oral bioavailability.

Fabrication and performance evaluation of graphene-supported PtRu electrocatalyst for high-temperature electrochemical hydrogen purification

The main aim of this study is to investigate the high-temperature electrochemical hydrogen purification (HT-ECHP) performances of graphene nanoplatelet (GNP) support material decorated with platinum (Pt) and platinum-ruthenium (PtRu) nanoparticles prepared by microwave irradiation technique. Prepared catalysts coupled to the phosphoric acid doped polybenzimidazole (PBI) membrane for HT-ECHP application. The structural and electrochemical properties of the catalysts were examined by thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transition electron microscopy (TEM) and cyclic voltammetry (CV) analyses. The characterization results indicate that the catalysts provided the necessary properties for HT-ECHP application. The HT-ECHP performances are investigated with reformate gas mixture containing hydrogen (H2), carbon dioxide (CO2) and carbon monoxide (CO) in the range of 140–180 °C. The results show that the electrochemical purification performances of the catalysts increase with increasing operating temperature. The highest H2 purification performance is obtained with PtRu/GNP catalyst. The high electrochemical H2 purification performance of the PtRu/GNP catalyst can be attributed to the strong synergistic interactions between Pt and Ru particles decorated on the GNP. These results advocate that the PtRu/GNP catalyst is a hopeful catalyst for HT-ECHP application.