Inhibition of protein misfolding and aggregation by steroidal quinoxalin-2(1H)-one and their molecular docking studies

A series of D-ring fused 16-substituted steroidal quinoxalin-2(1H)-one attached to an electron-releasing (ER) or electron-withdrawing (EW) groups via steroidal oxoacetate intermediate were synthesized to investigate their protein aggregation inhibition potential using human lysozyme (HLZ). The influence of the type of substituent at the C-6 positions of the quinoxalin-2(1H)-one ring on the protein aggregation inhibition potential was observed, showing that the EW moiety improved the protein aggregation inhibition potency. Of all the evaluated compounds, NO2-substituted quinoxalin-2(1H)-one derivative 13 was the most active compound and had a maximum protein aggregation inhibition effect. Significant stabilization effects strongly support the binding of the most biologically active steroidal quinoxalin-2(1H)-one with docking studies. The predicted physicochemical and ADME properties lie within a drug-like space which shows no violation of Lipinski's rule of five except compounds 12 and 13. Combined, our results suggest that D-ring fused 16-substituted steroidal quinoxalin-2(1H)-one has the potential to modulate the protein aggregation inhibition effect.

Highly radioiodine gas capture by 2-mercaptobenzimidazole-functionalized Bi/Mg oxide and effective iodine waste immobilization by etidronic-Bi2O3 complex

The present work prepared a novel BiMgO-2MBD (X = 0.42) material for iodine vapor capture in temperature conditions related to spent nuclear fuel reprocessing and nuclear accidents. BiMgO-2MBD (X = 0.42) was synthesized by a solvothermal process and exhibited an exceptional ultrafast and high iodine uptake with a capacity of 4352.12 mg/g and 5147.08 mg/g after 5 h at 75 °C and 150 °C, respectively. The TGA analysis shows that Bi/Mg oxide substrate highly contributed to improving the thermal stability of the functionalized BiMgO-2MB (X = 0.42) as indicated by the weight losses of the material components of 3.77 wt%, 29.32 wt%, and 97.72 wt%, respectively for Bi/Mg oxide, BiMgO-2MBD, and 2-MBD. The material characterization and DFT calculations indicate that 2-MBD played a significant role towards improving iodine capture capacity. For long-term and safe waste disposal, a chemically durable waste form was made from etidronic acid and Bi2O3, and successfully immobilized the iodine-loaded wastes (I2 @BiMgO-2MBD) which exhibited a low normalized leaching rate of 1.098 × 10-6 g.m2/day for 7 days under the PCT-A method. In addition, BiMgO-2MBD (X = 0.42) showed an ability to be reused after several regeneration cycles. The comparison with previously reported materials shows that the current BiMgO-2MBD (X = 0.42) is the first functionalized metal oxide comparable to metal-organic and covalent organic frameworks for iodine uptake. BiMgO-2MBD (X = 0.42) shows promising results for practical applications in the gas phase capture of radioactive iodine.

Dynamic structural evolution of MgO-supported palladium catalysts: from metal to metal oxide nanoparticles to surface then subsurface atomically dispersed cations

Supported noble metal catalysts, ubiquitous in chemical technology, often undergo dynamic transformations between reduced and oxidized states-which influence the metal nuclearities, oxidation states, and catalytic properties. In this investigation, we report the results of in situ X-ray absorption spectroscopy, scanning transmission electron microscopy, and other physical characterization techniques, bolstered by density functional theory, to elucidate the structural transformations of a set of MgO-supported palladium catalysts under oxidative treatment conditions. As the calcination temperature increased, the as-synthesized supported metallic palladium nanoparticles underwent oxidation to form palladium oxides (at approximately 400 °C), which, at approximately 500 °C, were oxidatively fragmented to form mixtures of atomically dispersed palladium cations. The data indicate two distinct types of atomically dispersed species: palladium cations located at MgO steps and those embedded in the first subsurface layer of MgO. The former exhibit significantly higher (>500 times) catalytic activity for ethylene hydrogenation than the latter. The results pave the way for designing highly active and stable supported palladium hydrogenation catalysts with optimized metal utilization.

Investigations on Chemically Synthesized Pure and Doped Manganese Dioxide Nanoparticles for Dye Removal and Photocatalytic Applications

Pure and Mg2+, Ni2+, Cd2+ doped MnO2 nanoparticles were synthesized by chemical co-precipitation method. These samples were characterised by PXRD, SEM, EDX, FTIR, UV-Vis-NIR, PL, Antibacterial, Cyclic Voltammetry, Dye Degradation and Photocatalytic studies. From the powder XRD studies, the crystallite size of the particle was calculated using Scherer formula and found that the synthesized nanoparticles were in the range from 10 to 12 nm. The morphology of all the synthesized samples was viewed from SEM micrograph. The composition and purity of the samples were identified from EDX studies. In FTIR spectra metal-oxygen stretching and bending modes of vibrations were observed. From the absorption spectra of UV-Vis optical analysis values of absorption coefficient, extinction coefficient, refractive index, real and imaginary part of optical dielectric constant and optical conductivity were compared. The band gap energy obtained from Tauc's plot varies from 1.21 to 1.51 eV exhibits semiconducting behaviour of all the synthesized samples. Investigations on photoluminecsence spectrum reveals blue shift in wavelength for doped nanooxides compared to pure MnO2. Antimicrobial activity of synthesised samples against gram positive and gram negative bacteria was determined. The obtained results reveal very high bacterial resistance in Cd2+ doped MnO2 nanoparticles with higher activity towards bacterial resistance compared to standard drug. The specific capacitance values were determined from Cyclic Voltammetry studies. Using the batch method of dye removing technique the percentage of malachite green dye removal was calculated. Also the photocatalytic efficiency of all the synthesized MnO2 samples in removing malachite green dye was studied by exposing to sunlight for different dosage and contact time. Ni2+ doped MnO2 shows relatively higher % of dye degradation capacity about 93% for 0.1 g of dosage of photocatalysts.

Surface Basicity and Hydrophilic Character of Coal Ash-Derived Zeolite NaP1 Modified by Fatty Acids

Zeolite NaP1 was found to display the highest affinity for CO2 in preliminary modifications of coal fly ash-derived zeolites (4A, Y, NaP1 and X) by four amines (1,3-diaminopropane, N,N,N',N'-tetramethylethylenediamine, Tris(2-aminoethyl)amine and ethylenediamine). In the second step, different fatty acid loaded NaP1 samples were prepared using palmitic, oleic and lauric acids. CO2 and H2O thermal programmed desorption (TPD) revealed changes in intrinsic basicity and hydrophilic character, expressed in terms of CO2 and H2O retention capacity (CRC and WRC, respectively). Infrared spectroscopy (IR), N2 adsorption-desorption isotherms and scanning electron microscopy allowed for correlating these changes with the type of interactions between the incorporated species and the zeolite surface. The highest CRC values and the lowest CO2 desorption temperatures were registered for NaP1 with the optimum content in palmitic acid (PA) and were explained in terms of the shading effect of surface acidity by the rise of basic Na+-palmitate salt upon cation exchange. The amine/fatty acid combination was found to paradoxically mitigate this beneficial effect of PA incorporation. These results are of great interest because they demonstrate that fatty acid incorporation is an interesting strategy for reversible CO2 capture.

Progress towards blue emitting MgO-ZnO-Ga2O3 nanocomposites synthesized by bio mediated route

MgO-ZnO-Ga2O3 nanocomposites are synthesized by solution combustion method using Aloe Vera gel as a reducing agent to increase the efficiency of blue emission. The appearance of Bragg reflections corresponding to MgO, ZnO and Ga2O3 clearly indicates the formation of nanocomposites. The surface morphology consists irregular shape and sized NPs. The Energy dispersive X-ray analysis confirms the purity of the sample. The band energy gap was tuned to 3.1 eV. The Photoluminescence excitation and emission spectra was discussed and compared it with emission spectra of individual oxides as well as with other reported blue emitted nanophosphors. Further, the chromaticity coordinates and Color correlated temperature coordinates clearly confirms their warm blue emission. Further, the powder dusting method was employed to collect the latent fingerprints on the pores and non-pores surfaces. The synthesized MgO-ZnO-Ga2O3 nanocomposites exhibits well-resolved ridge patterns that can be used to identify latent finger prints with clarity. From all these results, the present synthesized MgO-ZnO-Ga2O3 nanocomposite might find an application in display technology as a blue nanophosphor material and for latent finger print detection in crime investigation.

Synthesis and characterisation of lead-magnesium-boron nanocomposite for radiation shielding application

There is a need for the replacement of toxic lead with nontoxic materials in radiation shielding applications. Instead of pure lead, lead mixed compounds/mixtures/alloys are considered to be less toxic and hence preferred for radiation shielding purposes. The compounds with magnesium are said to be having good magnetic and mechanical properties. Meanwhile, the boron element avoids secondary radiation and absorbs neutrons. The compound which is a mixture of lead, magnesium and boron is expected to be a good shielding material for radiation for X-rays/gamma rays. Hence in the present study, we have synthesised the lead-magnesium-boron (LMB) nanocomposites (NCs) using the green synthesis approach for the first time. LMB is synthesised by solution combustion method using Aloe vera as a reducing agent. The synthesised NCs are characterised using well-known characterisation techniques. Powder X-ray diffraction confirmed the formation of multi-phase LMB NCs, and average crystal size is found to be 13-15 nm. Surface morphology and chemical composition are affirmed by SEM and EDX. The optical energy gap is found to be 1.87 eV. FTIR confirmed the functional groups. X-rays/gamma rays, neutrons and bremsstrahlung radiation shielding efficiency are measured by experimental and theoretical, compared with conventional shielding materials. LMB NCs have proved to be efficient. Hence, LMB NCs proved to be potential in X-rays/gamma rays, neutrons and bremsstrahlung radiation shielding.

Synthesis, biological activities, and future perspectives of steroidal monocyclic pyridines

Steroidal pyridines are a class of compounds that have been the subject of extensive research in recent years due to their potential biological activities. The introduction of a pyridine ring into the steroid skeleton can significantly alter the chemical and biological properties of the compound, making it more potent and/or selective for a particular target. Different synthetic methods have been developed for the preparation of steroidal pyridines. This review provides an overview of the synthesis, biological activities, and future perspectives of steroidal monocyclic dihydropyridines, tetrahydropyridines, and pyridines from 2005 to the present. The different synthetic methods that have been developed for the preparation of these steroids are discussed, as well as the proposed mechanisms and the biological activities that have been reported. Finally, the potential of steroidal monocyclic pyridines for the development of new drugs is discussed. This review is intended to provide a comprehensive overview of the field of steroidal monocyclic pyridines for researchers and scientists who are interested in this area of research. It is also hoped that this review will stimulate further research into the synthesis and biological activities of steroidal pyridines to develop new and improved drugs for the treatment of diseases.

Recovery of phosphorus and other minerals from greenhouse wastewater generated during soilless tomato cultivation by means of alkalizing agents

The research was aimed at determining the possibility of recovering part of nutrients by precipitation from greenhouse wastewater (GW) from soilless tomato cultivation. Analyses included such elements as: P, S, N, Cl, Ca, Mg, K, Mo, Mn, Fe, Zn, Cu, and B. Three alkalizing agents were tested in a pH range of 6.5-12.0: Ca(OH)2, KOH, and NH4OH, which simultaneously enrich greenhouse wastewater in calcium, potassium, and nitrogen. It was determined what dose of the alkalizing agent should be used, how the composition of the treated GW will change, how much and what kind of sludge will be formed, what will be the stability and technical possibility of sediment separation, and whether the type of alkalizing agent affects the course of the process. Precipitation triggered by the alkalizing agents proved to be an effective method for the recovery of phosphorus, calcium, magnesium, manganese, and boron, while it turned out ineffective in the case of the other elements tested, including nitrogen and potassium. Phosphorus recovery depended mainly on GW pH and forms of phosphate ions corresponding to this pH, and not on the alkalizing agent type. The pH value adjustment to pH = 9 for KOH and NH4OH and to pH = 9.5 for Ca(OH)2 ensured <99 % phosphorus recovery, which corresponded to P concentration in GW below 1 mgP/L and to the applied Ca(OH)2, KOH, and NH4OH doses of 0.20 g/L, 0.28 g/L, and 0.08 g/L, respectively. The highest P contents in the sludge were determined at pH = 7 and reached 18.0 %, 16.8 %, and 16.3 % in the experimental series with Ca(OH)2, KOH, and NH4OH, respectively. The sludge volume index increase along with pH increase up to pH = 10.5 for KOH and to pH = 11 for Ca(OH)2 and NH4OH.

Porous MgNiO2 Chrysanthemum Flower Nanostructure Electrode for Toxic Hg2+ Ion Monitoring in Aquatic Media

A simple hydrothermal synthesis approach was used to synthesize porous MgNiO2 Chrysanthemum Flowers (CFs) nanostructures and applied as a sensing electrode for quick detection of hazardous mercury (Hg2+ ions). The morphological, structural, and electrochemical properties of MgNiO2 CFs were investigated. The morphological characteristic of MgNiO2 CFs, with a specific surface area of 45.618 m2/g, demonstrated strong electrochemical characteristics, including cations in different oxidation states of Ni3+/Ni2+. Using a three-electrode system for electrochemical detection, the MgNiO2 CFs based electrode revealed a good correlation coefficient (R2) of ~0.9721, a limit of detection (LOD) of ~11.7 μM, a quick response time (10 s), and a sensitivity of 8.22 μA∙μM-1∙cm-2 for Hg2+ ions over a broad linear range of 10-100 μM. Moreover, the selectivity for Hg2+ ions in tap water and drinking water was determined, and a promising stability of 25 days by MgNiO2 CFs electrode was exhibited. The obtained results indicate that the developed MgNiO2 CFs are a promising electrode for detecting hazardous Hg2+ ions in water and have the potential to be commercialized in the future.

Evaluation of Structural Stability, Mechanical Properties, and Corrosion Resistance of Magnesia Partially Stabilized Zirconia (Mg-PSZ)

Nano Zirconia (ZrO2) has been used in dental implants due to having excellent mechanical properties and biocompatibility that match the requirements for the purpose. Zirconia undergoes phase transformation during heating: monoclinic (room temperature to 1170 °C), tetragonal (1170 °C to 2370 °C), and cubic (>2370 °C). Most useful mechanical properties can be obtained when zirconia is in a multiphase form or in partially stabilized zirconia (PSZ), which is achieved by adding small amounts of a metal oxide dopant, such as MgO (magnesia). This study aimed to synthesize nano Mg-PSZ from a local resource found in West Kalimantan, Indonesia, and examine its structural stability, biochemical stability, and mechanical properties. Nano Mg-PSZ was prepared from a zircon local to Indonesia, from West Kalimantan Province, MgSO4∙7H2O, and polyethylene glycol (PEG)-6000 was used as a template. The obtained t-ZrO2 after calcination at 800 °C was shown to be stable at room temperature. The highest percentage of the t-ZrO2 phase was obtained at Zr0.95Mg0.05O2 with a variation of 99.5%. The hardness of Mg-PSZ increased from 554 MPa for ZrO2 without MgO doping to 5266 MPa for ZrO2 with a doping of 10% MgO. An in vitro biodegradation test showed that the greater the concentration of MgO in doping the ZrO2, the greater the degradation resistance of Mg-PSZ in simulated body fluid (SBF) solution.

Thermal Properties and In Vitro Biodegradation of PLA-Mg Filaments for Fused Deposition Modeling

Additive manufacturing, in particular the fused deposition method, is a quite new interesting technique used to obtain specific 3D objects by depositing layer after layer of material. Generally, commercial filaments can be used in 3D printing. However, the obtention of functional filaments is not so easy to reach. In this work, we obtain filaments based on poly(lactic acid), PLA, reinforced with different amounts of magnesium, Mg, microparticles, using a two-step extrusion process, in order to study how processing can affect the thermal degradation of the filaments; we additionally study their in vitro degradation, with a complete release of Mg microparticles after 84 days in phosphate buffer saline media. Therefore, considering that we want to obtain a functional filament for further 3D printing, the simpler the processing, the better the result in terms of a scalable approach. In our case, we obtain micro-composites via the double-extrusion process without degrading the materials, with good dispersion of the microparticles into the PLA matrix without any chemical or physical modification of the microparticles.

Decoding the binding interaction of steroidal pyridines with bovine serum albumin using spectroscopic and molecular docking techniques

The present study reports a comprehensive and conformational aspect of binding of steroidal pyridines (1-6) with a model transport protein, bovine serum albumin (BSA) by fluorescence, UV-visible, circular dichroism, and molecular docking techniques. Quenching of BSA emission was attributed to the formation of the ground state complex after the compound (1-6) binds to the backbone of the protein. Synchronous fluorescence spectra reveals changes in the microenvironment of the aromatic residues. UV-visible absorption spectra further reiterate the quenching mechanism to be static and binding of compound (1-6) results in the formation of a ground-state complex. Circular dichroism spectra indicated that compound 1-3 causes unfolding and compound 4-6 leads to the stabilization of the protein structure. In addition, a molecular docking study revealed the binding pocket for the formation of the ligand-protein complex through hydrogen bonding and hydrophobic interactions. Furthermore, hemolytic activity suggested that the compounds (1-6) are biocompatible in nature. Evaluation of such steroid-protein interaction helps in better understanding of the biomolecular interaction of steroidal compounds with biomacromolecule and opens up new approaches in steroid based drug-design process.

Formation of nitrogen-containing six-membered heterocycles on steroidal ring system: A review

Steroidal heterocyclic compounds constitute interesting and promising scaffolds for drug discovery as they have displayed diverse chemical reactivity and several types of biological activities. This study is a concise report on the most recent advancements in the chemistry of the steroid skeleton, including reactions at the A, B, and D ring systems. The modern synthetic methods for the steroidal nitrogen-containing six-membered heterocyclic derivatives from 3-keto-, 6-keto-, 17-keto-, and 20-keto-steroids, as well as 2-Aldo-, 4-Aldo-, 6-Aldo-, and 16-Aldo-steroids, are discussed. However, some other methods for the synthesis of steroidal N-containing 6-membered heterocyclic derivatives are also included. These compounds have shown therapeutic potential as cytotoxic agents against various cell lines and have also shown antiproliferative, anti-inflammatory, and antioxidant activities. Therefore, they could be used as prospective candidates for the development of various medications. This paper not only describes synthetic details involved in creating N-containing 6-membered heterocyclic steroid derivatives, but also provides a brief overview of the medicinal applications of these compounds. This information will be highly useful for the medicinal chemists conducting research in this field.

Microwave-assisted one-pot multicomponent synthesis of steroidal pyrido[2,3-d]pyrimidines and their possible implications in drug development

Protein misfolding can lead to fibrillar and non-fibrillar deposits which are the signs of countless human diseases. A promising strategy for the prevention of such diseases is the inhibition of protein aggregation, and the most crucial step toward effective prevention is the development of small molecules having the potential for protein-aggregation inhibition. In this search, a series of novel steroidal pyrido[2,3-d]pyrimidines have been synthesized employing steroidal ketone, substituted aldehydes, and 2,6-diaminopyrimidin-4(3H)-one through the microwave-assisted one-pot multicomponent methodology. The aggregation inhibition potential of newly synthesized compounds was evaluated on human lysozyme (HLZ). All the synthesized compounds were found to be efficient in the inhibition of protein aggregation in carefully designed in vitro experiments. Moreover, molecular docking studies also determine the binding interactions between all the synthesized compounds and native HLZ through hydrogen bonding. The structures of synthesized compounds were also elucidated using various spectroscopic techniques.

Water reclamation from anodizing wastewaters by removing reactive silica with adsorption and precipitation methods

Water stress is a current environmental menace mainly driven by over exploitation of aquifers, which is triggering poor water quality with high concentration of minerals in extracted groundwater. Particularly, silica is widespread in natural water supplies due to weathering processes of silicates occurring in contact with water, light, air, and other factors. However, due to groundwater over extraction the concentration of silica has increased during the last years in aquifer reservoirs from Aguascalientes State (México). In this context, it is very important to note that the removal of silica compounds from water is challenging and different methods can be used to avoid embedding problems in different industries. In the present work, the removal of reactive silica from synthetic solutions as well as from real wastewaters from an industrial anodizing process was studied using adsorption and chemical precipitation methods. Twelve commercial materials of different nature were used for adsorption tests, while seven precipitant agents were applied in the precipitation experiments. Adsorption tests were performed in batch systems with constant stirring at 30 °C and at different pH values (7 and 9). Precipitation experiments were carried out in batch systems and the best conditions for silica removal were found using an L₉ orthogonal array of the Taguchi method employing molar ratio, pH of wastewater, stirring time and temperature as experimental factors. Adsorption results showed that Ferrolox (Iron (III) hydroxide-base adsorbent) was the most efficient sorbent for reactive silica removal from synthetic solutions and the anodizing wastewater. Also, the reactive silica adsorption was higher at pH 9 as compared to that measured at pH 7 and the adsorbed quantity at pH 9 was 16.22 and 11.25 mg/g for the synthetic solution and anodizing wastewater, respectively. According to molecular simulation, the main interaction between Ferrolox and silica species was related to the formation of hydroxo-complexes and to the interaction of Fe with oxygen of silica species. Additionally, magnesium chloride was the best precipitating reagent for reactive silica achieving up to 87% removal. According to ANOVA analysis of Taguchi method, pH was the most influential factor during the precipitation of reactive silica with a variance value of 81.42, while values lower than 3 were obtained for the rest of parameters. Overall, the present work is reporting for the first time the removal of reactive silica from anodizing wastewaters with promising results that can be implemented at full scale for water reclamation, which may significantly contribute to manage water reservoir in the region sustainably.

A simple co-precipitation sorbent-based preconcentration method for the analysis of fungicides in water and juice samples by high-performance liquid chromatography coupled with photodiode array detection

A magnesium hydroxide co-precipitation sorbent-based method in the presence of an anionic surfactant (e.g., sodium dodecylbenzenesulfonate) and high-performance liquid chromatography were used to preconcentrate and analyze fungicides in water and apple juice samples. The preconcentration procedure can be accomplished in a single step based on the co-precipitation of target fungicides and magnesium chloride in the presence of surfactant in a sodium hydroxide solution (pH 11) and a white precipitate gel was simply obtained after centrifugation. The property of precipitate phase was subsequently characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffractometry. Under the optimum conditions, the developed method exhibited good sensitivity, with an enrichment factor of 11–18 and limits of detection of approximately 1–5 μg/L for water samples and 7–10 μg/L for apple juices. High reproducibility was achieved with a relative standard deviation of less than 11%, and a good recovery range of 72% to 120% was also obtained. The proposed method was shown to be a simple preconcentration procedure for concentrating fungicides in the samples investigated.

Influence of aluminate and silicate on selenate immobilization using alkaline-earth metal oxides and ferrous salt

Effects of aluminate and silicate species on the SeO₄^2- immobilization using alkali-earth metal oxides and ferrous species have not been clearly elucidated. In the present study, Al and Si species were separately added into MgO/Fe(II) and CaO/Fe(II) reactions containing SeO₄^2-, studied by toxicity characteristic leaching procedure (TCLP), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray absorption fine structure (XAFS), and PHREEQC simulation. Approximately 42 % of SeO₄^2- was reduced to SeO₃^2- for MgO/Fe(II) reaction in the presence of Al species, being consistent with the case without Al species. The Al species only showed slight inhibition of Se leaching for the MgO/Fe(II) reaction. Most of Se oxyanions were adsorbed onto Mg(OH)₂ through outer-sphere complexation. For CaO/Fe(II) reaction, all of SeO₄^2- was reduced to SeO₃^2- with or without Al species. However, the Se leaching amount (3 %) of sample added with Al species (CE3) is much lower than that (12 %) of sample without Al species (CE2). This is mainly because SeO₃^2- can be sorbed onto the iron-based minerals through binuclear bidentate corner-sharing (²C) complexation instead of monodentate mononuclear corner-sharing (¹V) complexation of the case without Al species. On the other hand, SeO₄^2- was not reduced to SeO₃^2- in the presence of silicate, and almost all of Se was leached out for silicate-contained samples except CaO/Fe(II) reaction with the addition of Al species. This is due to the polymerization of Al and Si species under a high-alkalinity environment, thereby stabilizing SeO₄^2- in the amorphous silicon-aluminum structure and contributing to the decrease of Se leaching.

Synthesis of steroidal dihydropyrazole derivatives using green ZnO NPs and evaluation of their anticancer and antioxidant activity

Zinc oxide nanoparticles (ZnO NPs) were synthesized by a green method using Azadirachta indica leaf extract. The structure of the prepared ZnO (NPs) were characterized by FT-IR, XRD, SEM-EDX and TEM analyses. The biosynthesized ZnO (NPs) were then used as a catalyst for the synthesis of steroidal dihydropyrazole derivatives through a one-pot multicomponent reaction involving phenyl acetylene and hydrazine derivatives. The anticancer activity of newly synthesized compounds were evaluated against three cancer cell lines namely HeLa (human cervical carcinoma), Hep3B (human hepatocellular carcinoma) and MCF7 (human breast adenocarcinoma) by MTT assay. The tested compounds were found to be active against all cancer cell lines and less toxic towards normal peripheral blood mononuclear cells (PBMCs). Antioxidant activity have also been investigated via free radical scavenging ability using DPPH, FRAP and ABTS assay. The tested compounds were found to exhibit moderate to good antioxidant activity which increases with increase in the concentration of steroidal dihydropyrazoles. Among all the tested steroidal dihydropyrazoles, compound 17 is found to be most active.

Photocatalytic and Electrochemical Activity of Magnesium Oxide Nanoballs Synthesized via a Hydrothermal Route

Currently, there is growing concern about minimizing the environmental impacts caused by the generation of waste on water, soil, air pollution, and contamination of the environment in general. Magnesium oxide (MgO) nanoballs (NBs) were synthesized by the hydrothermal method followed by a calcination process. The average size of particles dispersed in deionized water was 159.2 ± 70 nm. The energy band gap was calculated to be 5.14 eV. The magnetic behavior, cyclic voltammetry, and electrochemical impedance of MgO NBs were studied. Under visible-light irradiation, the photocatalytic activity of MgO nanoballs was investigated by methylene blue (MB) dye. Results showed that photodegradation for MB under visible light irradiation for 120 min and degradation results are fitted well with pseudo-first-order reaction kinetics with a rate constant of 0.00252 min−1 and a correlation coefficient of 0.96.

Variously Prepared Zeolite Y as a Modifier of ANFO

In the presented research, we investigated Ammonium Nitrate Fuel Oil (ANFO), with the addition of variously modified zeolite Y as an attractive explosive. Analysis of both blasting tests and thermodynamic models of blasting properties led to the conclusion that the addition of zeolite Y enhanced the detonation properties of such prepared ANFO via the growth of the detonation pressure, temperature, compression energy, and heat of the explosion. Generally, the modification of ANFO with variously prepared zeolite Y also reduced the volume of (CO_x + NO_x) post-blast fumes. Furthermore, it was found that the ANFO's velocity of detonation (VOD) could be controlled by the choice of the way of zeolite Y modification. Namely, for zeolite Y without Mg, as well as Mg-Y prepared via the impregnation method, the VOD rose. The opposite effect was observed when ANFO was modified with Mg-Y, obtained from the deposition of Mg over zeolite Y via the ultrasonic-assisted procedure.

Electroless Deposits of ZnO and Hybrid ZnO/Ag Nanoparticles on Mg-Ca0.3 Alloy Surface: Multiscale Characterization

ZnO and hybrid of ZnO/Ag structures in the nanometer size were electroless deposited on the Mg-Ca0.3 alloy surface, achieved from aqueous solutions (10−3 M at 21 °C) of ZnO (suspension), Zn(NO3)2 and AgNO3. The surface characterization of the deposits was carried out by Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), X-Ray Photoelectron Spectroscopy (XPS), Fourier transform infrared (FTIR), UV-Visible and Raman spectroscopy. The nanoparticles (NPs) area size distribution analysis revealed that the average of ZnO-NPs was ~85 nm. Likewise, the Ag-NPs of electroless deposits had an average area size of ~100 nm and nucleated in the vicinity of ZnO-NPs as Ag+ ions have been attracted by the negatively charged O2− atoms of the Zn-O dipole. The ZnO-NPs had the wurtzite structure, as indicated by Raman spectroscopy analysis and XRD complementary analysis. The UV-Visible spectroscopy analysis gave a peak at ~320 nm associated with the decrease in the imaginary part (k) of the refractive index of Ag-NPs. On the Mg-Ca0.3 surface, MgO, Mg(OH)2 and MgCO3 are present due to the Mg-matrix. XRD spectra of Ag-NPs indicated the presence of planes arranged with the FCC hexagonal structure. The reported hybrid ZnO/Ag electroless deposits of NPs are of interest for temporary implant devices, providing antibacterial properties to Mg-Ca0.3 surface, a widely used biodegradable material.

Recent advances on synthesis and biological activities of C-17 aza-heterocycle derived steroids

Steroids modification for improving their biological activities is one of the most efficient and fruitful methods to develop novel medicines. Steroids with aza-heterocycles attaching to the C-17 owing various biological activities have received great attentions and some of the compounds are developed successfully as drugs. In this review, the research of the syntheses and biological activities of steroids bearing various aza-heterocycles published in the last 8 years is assembled, and some important structure-activity relationships (SARs) of active compounds are presented. According to the analysis of the literatures and our experiences in this field, the potential of aza-heterocyclic steroids as medicinal drugs is proposed.

Enhanced antibacterial activity of Rosehip extract-functionalized Mg(OH)2 nanoparticles: An in vitro and in vivo study

The development of nanoparticles as antimicrobial agents against pathogenic bacteria has emerged as one of the leading global healthcare challenges. In this study, Mg(OH)₂ NPs with controlled morphology and nanometric size, using two distinct counterions, chloride or nitrate, have been synthesized using Rosehip (RH) extract that has privileges beyond conventional chemical and physical methods. Various physicochemical techniques were used to characterize the RH-functionalized Mg-based NPs. They exhibited a spherical shape with a diameter of ~10 nm, low crystallinity compared to non-functionalized NPs, high polyphenol content, and negative zeta potential in three different media (H₂O, TSB, and cell medium). The resulting RH-functionalized Mg-based NPs also exhibited an increased antibacterial activity against Gram-positive (S. Epidermis and S. aureus) and Gram-negative (E. Coli) bacteria compared to those prepared in pure water (0 % RH), an effect that was well evident with low NPs contents (250 μg/mL). A preliminary attempt to elucidate their mechanism of action revealed that RH-functionalized Mg-based NPs could disrupt cellular structures (bacterial cell wall and cytoplasmic membrane) and damage the bacterial cell, as confirmed by TEM imaging. Noteworthy is that Mg-based NPs exhibited higher toxicity to bacteria than to eukaryotic cells. More significantly, was their enhanced in vivo efficacy in a Galleria mellonella invertebrate animal model, when infected with S. aureus bacteria. Overall, our findings indicate that well-engineered Rosehip magnesium-based nanoparticles can be used as a green non-cytotoxic polyphenolic source in different antibacterial applications for the biomedical industry.

Insight into the role and mechanism of polysaccharide in polymorphous magnesium oxide nanoparticle synthesis for arsenate removal

The low cost and non-toxic of magnesium oxides make it a potential eco-friendly material for arsenic removal. Polysaccharide is a kind of green modifier to obtain nanoscale MgO particles with a higher adsorption affinity. In this study, the impact of chain structures of polysaccharides on the morphology features and arsenate removal efficiency of MgO-NPs were investigated. Pullulan and starch facilitated the synthesis of flower-like MgO-NPs, and pectin facilitated the synthesis of plate-like ones. Although the two kinds of flower-like MgO-NPs undergone similar time to reach equilibrium, the one obtained from the starch-synthesis route showed a higher arsenate adsorption capacity (98 mg g^-1), due to that their bushy and smaller petals on the surface provide more active sites for arsenic adsorption. The pectin-synthesis route also produced MgO-NPs with higher arsenate adsorption capacity (101 mg g^-1), ascribed to stacking of nano-plates on their surfaces facilitated to form defect surfaces. However, due to their lower BET area, the plate-like MgO-NPs took twice times to reach equilibrium for arsenic adsorption compared with the others. In the stage for the hydrolysis of MgO, hydroxyl groups on the polymer chain provide active sites to physically trap or bond with MgO particles and then to produce hydrolyzed precursors. The poly chain containing inter- and intra-hydroxyl groups directed MgO molecular growing into hydroxide crystals with 3D frameworks during their nucleation and growth. However, pectin only provides inter-hydroxyl groups and directs to form hydroxides with 2D frameworks. Furthermore, the rapid-nucleation vs. slow-growth model in the stage of pyrolysis of hydroxide crystals successfully interprets the thinner petals and complex chemical phases of the final nanoparticles obtained from the pullulan-synthesis route. This work may provide direction and perspectives for the rational design of well-performing MgO materials for arsenate removal.

Composite of Layered Double Hydroxide with Casein and Carboxymethylcellulose as a White Pigment for Food Application

Titanium dioxide (TiO₂) is commonly used in food, cosmetic, and pharmaceutical industries as a white pigment due to its extraordinary light scattering properties and high refractive index. However, as evidenced from recent reports, there are overriding concerns about the safety of nanoparticles of TiO₂. As an alternative to TiO₂, Mg-Al layered double hydroxide (LDH) and their composite containing casein and carboxymethyl cellulose (CMC) were synthesized using wet chemistry and compared with currently used materials (food grade TiO₂ (E171), rice starch, and silicon dioxide (E551)) for its potential application as a white pigment. These particles were characterized for their size and shape (Transmission Electron Microscopy), crystallographic structure (X-Ray Diffraction), agglomeration behavior and surface charge (Dynamic Light Scattering), surface chemistry (Fourier Transform Infrared Spectroscopy), transmittance (UV–VIS spectroscopy), masking power, and cytotoxicity. Our results showed the formation of typical layered double hydroxide with flower-like morphology which was restructured into pseudo-spheres after casein intercalation. Transmittance measurement showed that LDH composites had better performance than pristine LDH, and the aqueous suspension was heat and pH resistant. While its masking power was not on a par with E171, the composite of LDH was superior to current alternatives such as rice starch and E551. Sustainability score obtained by MATLAB^® based comparison for price, safety, and performance showed that LDH composite was better than any of the compared materials, highlighting its potential as a white pigment for applications in food.

Saharan Dust Storm Aerosol Characterization of the Event (9 to 13 May 2020) over European AERONET Sites

This research was aimed at investigating the Saharan dust cloud recorded on 11 and 12 May 2020, by AERONET AOD stations in Italy, Austria, Slovakia, Poland, Ukraine, and Romania and determining whether it affected the area of the Republic of Moldova. During this period, the Chisinau AERONET monitoring site was not operational. The incentive for the investigation was the discovery of a high sediment load in rainwater collected on 12 May 2020 in Pelinia, a village in the Dochia district of the Republic of Moldova, in the southeastern part of Europe (47.8780 latitude, 27.8344 longitude), which could have originated from the Saharan dust storm. Backward trajectory analysis with NOAA’s HYSPLIT model confirmed that the Saharan dust storm impacted the village of Pelinia. Scanning electron microscopy coupled with electron dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FTIR) analysis of Pelinia rainwater sediments confirmed the chemical composition and morphological structure of Saharan dust particles. The particle size of the sediments matched the measurements at the AOD stations at Timisoara and Magurele, supporting the suggestion that Saharan dust probably entered the Republic of Moldova from Romania. FTIR analysis identified chemical compounds such as carbon dioxide, carbonates, sulfates, ferrocyanides, and organics (amines, amides, polypeptides, imines, oximes, pyrroles, aldehydes, sulfoxides, sulfones, nitro-derivatives) that were adsorbed and/or absorbed from the atmosphere, consistent with Saharan dust aerosols. Bio-allergens such as pollen were detected in the SEM images, showing the role of Saharan dust in transporting and spreading this kind of biological material. This study highlights the risk of Saharan dust clouds to humans, animals, and plants, but also its potential benefits for agriculture when suitable conditions are met in this regard.

Synthesis, photocatalytic and antibacterial activities of a PDS-activated MgO nanocatalyst: experimental and theoretical studies

PDS activation of MgO nanoparticles provides the opportunity to explore their applications and activities.

Novel NiMgOH-rGO-Based Nanostructured Hybrids for Electrochemical Energy Storage Supercapacitor Applications: Effect of Reducing Agents

This paper describes the synthesis and characterization of NiMgOH-rGO nanocomposites made using a chemical co-precipitation technique with various reducing agents (e.g., NaOH and NH4OH) and reduced graphene oxide at 0.5, 1, and 1.5 percent by weight. UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, a particle size analyzer, and cyclic voltammetry were used to characterize the composite materials. The formation of the NiMgOH-rGO nanocomposite with crystallite sizes in the range of 10–40 nm was inferred by X-ray diffraction patterns of materials, which suggested interlayers of Ni(OH)2 and Mg(OH)2. The interactions between the molecules were detected using Fourier-transform infrared spectroscopy, while optical properties were studied using UV-visible spectroscopy. A uniform average particle size distribution in the range of 1–100 nm was confirmed by the particle size analyzer. Using cyclic voltammetry and galvanostatic charge/discharge measurements in a 6 M KOH solution, the electrochemical execution of NiMgOH-rGO nanocomposites was investigated. At a 1 A/g current density, the NiMgOH-rGO nanocomposites prepared with NH4OH as a reducing agent had a higher specific capacitance of 1977 F/g. The electrochemical studies confirmed that combining rGO with NiMgOH increased conductivity.

Boosting the Catalytic Performance of Co/Mg/La Catalyst for Ammonia Synthesis by Selecting a Pre-Treatment Method

The influence of the calcination process on the physicochemical properties and catalytic behavior of the Co/Mg/La catalysts for ammonia synthesis has been investigated. The catalysts were prepared using the different thermal pre-treatment methods prior to the activation, i.e., drying and calcination, and the respective activities for ammonia synthesis were assessed. It was found out that changing from air calcination prior to activation to direct activation of the co-precipitated species led to the different catalytic performances. The most favorable catalytic performance was achieved with Co/Mg/La prepared by calcination in air. Detailed characterization methods, employing e.g., XRPD, H2-TPD, N2-TPD, CO2-TPD, SEM, and TEM, showed that the superior catalytic behavior of this catalyst was attributed to its strong basicity and favorable adsorption properties toward hydrogen and nitrogen.

Vacancy-Mediated Hydrogen Spillover Improving Hydrogen Storage Properties and Air Stability of Metal Hydrides

Hydrogen storage in metal hydrides is a promising solution for sustainable and clean energy carriers. Although Mg-based metal hydrides are considered as potential hydrogen storage media, severe surface passivation has limited their industrial application. In this study, a simple, cheap, and efficient method is proposed to produce highly reactive and air-stable bulk Mg-Ni-based hydrides by rapid treatment with water for 3 min. The nickel-decorated Mg(OH)₂ nanosheets formed in situ during hydrolysis can provide a pathway for hydrogen desorption via vacancy-mediated hydrogen spillover, as revealed by density functional theory calculations, thereby significantly decreasing the peak dehydrogenation temperature by 108.2 °C. Moreover, water-activated hydrides can be stored under ambient conditions without surface decay and activity loss, exhibiting excellent air stability, which can be attributed to the chemical stability of the surface layer. The results provide alternative insights into the design of highly active, air-stable metal hydrides with low cost and promote the industrial application of hydrogen energy.

Facing Seawater Splitting Challenges by Regeneration with Ni-Mo-Fe Bifunctional Electrocatalyst for Hydrogen and Oxygen Evolution

Hydrogen, produced by water splitting, has been proposed as one of the main green energy vectors of the future if produced from renewable energy sources. However, to substitute fossil fuels, large amounts of pure water are necessary, scarce in many world regions. In this work, we fabricate efficient and earth-abundant electrodes, study the challenges of using real seawater, and propose an electrode regeneration method to face undesired salt deposition. Ni-Mo-Fe trimetallic electrocatalyst is deposited on non-expensive graphitic carbon felts both for hydrogen (HER) and oxygen evolution reactions (OER) in seawater and alkaline seawater. Cl^- pitting and the chlorine oxidation reaction are suppressed on these substrates and alkalinized electrolyte. Precipitations on the electrodes, mainly CaCO₃ , originating from seawater-dissolved components have been studied, and a simple regeneration technique is proposed to rapidly dissolve undesired deposited CaCO₃ in acidified seawater. Under alkaline conditions, Ni-Mo-Fe-based catalyst is found to reconfigure, under cathodic bias, into Ni-Mo-Fe alloy with a cubic crystalline structure and Ni : Fe(OH)₂ redeposits whereas, under anodic bias, it is transformed into a follicular Ni:FeOOH structure. High productivities over 300 mA cm^-2 and voltages down to 1.59 V@10 mA cm^-2 for the overall water splitting reaction have been shown, and electrodes are found stable for over 24 h without decay in alkaline seawater conditions and with energy efficiency higher than 61.5 % which makes seawater splitting promising and economically feasible.

Readily-fabricated supported MgO catalysts for efficient and green synthesis of diethyl carbonate from ethyl carbamate and ethanol

Developing cost-effective, high-efficiency and heterogeneous catalysts is of prime importance for the green synthesis of diethyl carbonate (DEC) from ethyl carbamate (EC) and ethanol. Herein, a series of MgO/γ-Al2O3 catalysts were readily fabricated by an impregnation method for DEC synthesis from EC and ethanol. The activities of the as-prepared MgO/γ-Al2O3 catalysts as well as the individual MgO or γ-Al2O3 were first tested in the batch reactor. Among the investigated samples, the MgO/γ-Al2O3 with a MgO loading of 10 wt% (denoted as 10% MgO/γ-Al2O3) exhibited the largest amount of stronger basic sites, and the highest activities with EC conversion of 41.8% and DEC yield of 30.4%, respectively. Furthermore, the DEC yield was greatly boosted to 52.1% with a high DEC selectivity of 93.8% over the 10% MgO/γ-Al2O3 catalyst under the optimized reaction conditions in the fixed bed reactor, outperforming most of the reported catalysts.

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

Microwave-assisted (MWA) multicomponent reactions (MCRs) have successfully emerged as one of the useful tools in the synthesis of biologically relevant heterocycles. These reactions are strategically employed for the generation of a variety of heterocycles along with multiple point diversifications. Over the last few decades classical MCRs such as Ugi, Biginelli, etc. have witnessed enhanced yield and efficiency with microwave assistance. The highlights of MWA-MCRs are high yields, reduced reaction time, selectivity, atom economy and simpler purification techniques, such an approach can accelerate the drug discovery process. The present review focuses on the recent advances in MWA-MCRs and their mechanistic insights over the past decade and shed light on its advantage over the conventional approach.

Evaluation of Fe-Mg Binary Oxide for As (III) Adsorption-Synthesis, Characterization and Kinetic Modelling

Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO₃·9H₂O and MgNO₃·6H₂O in a proportion of molar concentration 1:1 and was later evaluated in removing As (III) from contaminated waters. Characterization of the prepared nanomaterial was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX) and ultraviolet–visible spectrophotometry (UV-VIS). Experimental studies on batch scale were carried out, examining the effect of varying initial concentrations of metal, adsorbent dosage, application time and initial pH on removal efficiency. Arsenic removal increased on increasing adsorbent dosage (0.1–1 g/L) but trend reversed on increasing initial arsenic concentration attaining q_max of 263.20 mg/g. Adsorption was quite efficient in pH range 4–8. Freundlich fitted better for adsorption isotherm along with following Pseudo-2nd order kinetics. The reusability and effect of co-existing ions on arsenic adsorption, namely SO₄²⁻, CO₃²⁻ and PO₄³⁻ were also explored with reusability in 1st and 2nd cycles attained adsorptive removal up to 77% and 64% respectively. The prepared nano-adsorbent showed promising results in terms of high arsenic uptake (q_max of 263.20 mg/g) along with facile and cost-effective synthesis. Thus, the co-precipitation technique used in this work is a simple one step procedure without any use of any precursor as compared to most of the other procedures used for synthesis.