Basic Medium Research Articles

Influence of Acylation by Hydroxycinnamic Acids on the Reversible and Irreversible Processes of Anthocyanins in Acidic to Basic Aqueous Solution.

In this work, the thermodynamics and kinetics of the reversible and irreversible processes of cyanidin 3,5-O-diglucoside and cyanidin 3-O-(2-O-glucosyl, 6-O-sinapoyl)glucoside-2-O-glucoside, 5-O-glucoside were studied by covering all pH range (holistic approach). The acylation (i) decreases the mole fraction of the colorless hemiketal in acidic medium and increases that of the colored quinoidal base, (ii) expands the pH domain of the flavylium cation, and (iii) moderately decreases the rate of tautomerization and isomerization of the neutral and monoanionic species. Degradation of cyanidin-3,5-O-diglucoside in a basic medium occurs in two distinct stages. After the formation of the anionic quinoidal bases (double proton loss from flavylium cation), a fast kinetic step, only observed by stopped flow, gives rise to the B4n- hydroxide adducts (n = 2,3) in equilibrium with the respective quinoidal bases An- (n = 1,2), leading to a first transient state. The quinoidal bases and B4n- adducts disappear completely from the first to a second transient state by means of two parallel reactions: (i) one reversible, giving the anionic cis- and trans-chalcones, (ii) the other irreversible, giving degradation products and exhibiting a pH-dependent bell-shaped mole fraction with maximum around pH = 12. From the second transient state, the anionic chalcones disappear completely in a few days. Acylation prevents formation of the first transient state. All of these effects are compatible with anthocyanidin-acyl π-stacking interactions (intramolecular copigmentation).

Isolation, Characterization, and Optimization of Culture Medium for Local Straw-Degrading Bacteria from Northeastern Black Soils of China

In order to solve the problem of low and poor straw degradation in typical black soil areas of Northeast China, the present study was carried out to screen the potential of in situ strains with cellulose degradation ability from black soils of Northeast China to play a role in the resourceful utilization of straw and the development of sustainable agriculture. The straw degradation potential of the strains was evaluated by combining sodium carboxymethyl cellulose plate screening and cellulase viability assay; the species identification of the strains was carried out by morphology, physiology, biochemistry, and molecular biology; and the basic medium formulation of the strains was optimized by Box–Behnken response surface methodology. Ten cellulose-degrading strains were identified: ZL-5, ZL-69, ZL-88, ZL-95, ZL-111, ZL-137, ZL-139, ZL-140, ZL-187, and ZL-216, of which ZL-139 had the highest cellulase production capacity, with a cellulase secretion of 7.8781 U/mL in the enzyme-producing medium. ZL-139 was identified as Bacillus cereus; the optimized best formulation was glucose—4.284 g/L, yeast extract—1.454 g/L, MgSO4—0.417 g/L, KH2PO4—0.5 g/L, KH2PO4—0.5 g/L, K2HPO4—1.5 g/L, and NaCl—1.0 g/L. In conclusion, strain ZL-139 has good potential for crop straw degradation and can be a candidate strain for a straw-rotting agent in northeast China, with promising prospects for development and utilization.

Kemiri Sunan Buds Induction (Reutealis trisperma (Blanco) Airy Shaw) For In Vitro in Ms Media with Different Concentrations of the Substance Growing Manager

Need oil fuel in Indonesia has increased. Oil production reached only 410,000 barrels per day while the needs of up to 1 million barrels per day. One plant is capable of producing biofuels is Pecan sunan. Vegetative reproduction has been hampered by the limited number of obtained so that necessary research in vitro. This research aims to know the concentration of the substance growing balance sitokinin (BA, TDZ and kinetin) and Auxin (NAA) in Pecan sunan buds induces on the MS medium. Experimental design used was Complete Random Design simple. The treatment is the composition of the basic MS medium with medium that is combined with the astringent balance grow NAA (0.5 mg/l), BA (1-3 mg/l), TDZ (0.2 mg/l) and kinetin (2 mg/l). The result of the observation form buds, but callus changes color and size kalus. Before and after color callus subculture of potentially forming buds is the A9 (MS + 0.5 mg/l NAA + 3 mg/l BA + 2 mg/l kinetin). While kalus response tends to be good on the A5 is 0 MS media (MS + 0.5 mg/l NAA + 2 mg/l BA + 0.2 mg/l TDZ) and G media is A2 (MS + 0.5 mg/l NAA + 2 mg/l BA).

Trace Ru Incorporation Boosted Co2P Nanorods for Superior Water Electrolysis and Substrate-Paired Electrolysis Toward Value-Added Chemicals in Alkaline Medium.

Electro-valorization of biomass-derived chemicals has ensured sustainable production of value-added products, an effective approach for reducing carbon footprint, through renewable energy. Electrochemical oxidation and reduction reactions in aqueous media using H2O as a potential source for active hydrogenated and oxygenated species fulfill the purpose. In this study, Ru─Co2P nanorods are explored as a bifunctional electrocatalyst toward valorization of Organics at basic media. The in-situ electrogenerated Co3+ and Co4+ species act as active oxidants toward product selectivity. An overpotential of 68mV is found for hydrogen evolution reaction (1m NaOH) with Ru─Co2P. Further, used as cathode, Ru─Co2P effectively reduces furfuraldehyde to furfuryl alcohol and p-nitrophenol to p-aminophenol. Ru doping enables ease of formation of active species both for reduction and oxidation, faster charge transfer between catalyst to absorbates. Density Functional Theory calculation establishes Ru incorporation in Co2P surface results in enhanced adsorption of substrates. Ru doping modulates the electronic structure of Co2P which changes the density of states resulting in faster water dissociation and water splitting. To reach 10mAcm-2 current density only 1.6V is required for water electrolysis, whereas 1.4V is enough for substrate-paired electrolysis with simultaneous oxidation of benzyl alcohol and reduction of p-nitro phenol.

Developing a New Method for the Estimation of Valsartan (VST) in Pharmaceutical Dosage Samples by Using Diazotization and Coupling Reactions Spectrophotometrically

Introduction: A new method for valsartan (VST) estimation in pharmaceutical dosage samples by spectrophotometry was developed. Method: The method was based on the formation of coloured dye by the diazotization reaction of 3-amino-2-naphthol with sodium nitrite in an acidic medium to form diazonium compounds, which were then coupled with VST in a basic medium. Results: The drug sample showed linearity in the range 4.6 - 24.2 μgmL-1, and the λmax was found at 432nm. Sandell’s sensitivity (9.950×10-3), Molar absorbtivity (Ɛ= 4.377×104), regression equa-tion (y= 0.0775x + 0.0041), correlation coefficient (r2= 0.968), detection limit (DL= 0.668) and quantitation limit (QL= 2.024) were evaluated. Conclusion: The percentage recovery of the drug samples was found to be 100%. This method successfully determined VST in Pharmaceutical dosage samples.

Selective Detection of Divalent Cations (Cu2+, Zn2+, Pb2+) and Anions (SO42-, S2-, CO32-) Using a pH-Sensitive Multi-functional Schiff Base inNeutralMedium.

A new Schiff base-based multi-cation/anion probe (L) has been synthesized and characterized using HR-MS, FT-IR, 1H, and 13C NMR techniques. The Schiff base motif provides specific binding sites that detect cations and anions by generating distinct optical output signals upon interaction. A noticeable color change of the probe solution was observed from pale yellow to various shades of yellow upon adding cations such as Cu2+, Zn2+, and Pb2+ and anions such as CO32⁻, S2⁻, and SO42⁻. This color change results from forming complexes like M3L2 with metal ions. Whereas origin of color in presence of anion were attributed due to the deprotonation of acidic proton in the ligand. Moreover, the complexes formed by Zn2+, S2/CO32⁻ ion with L are fluorescent, enabling the detection of Cu2+ and SO42⁻ using the Stern-Volmer plot, with a limit of detection (LODs) of 8.48µM and 10.47µM, respectively. Additionally, increasing the pH of the probe solution above 8 reveals a significant enhancement of fluorescence intensity due to the deprotonation of phenolic -OH and amide -NH in the presence of hydroxide ions. This emission in the basic medium is quenched by Cu2+ ions and restored when Cu2+ is complexed with EDTA. A logic gate has also been constructed for understanding the TURN-OFF-TURN-ON mechanism involving Cu2+ ions and EDTA. Overall, the versatile performance of a single probe L opens up new possibilities as a multifunctional sensor, making it highly suitable for practical applications.

Facile synthesis of green graphite-based (Ni/Cu/N) MOF composite for a methanol oxidation reaction

Recently, direct methanol fuel cells (DMFCs) have been regarded as the greatest energy-producing owing to their low operating temperature, high production rate of methanol, and low greenhouse gas emission. However, the energy conversion efficiency of the DMFCs is still unsatisfactory due to the slow kinetics of the fuel oxidation reaction. So, an economic electrocatalyst with high efficiency and good stability is still needed. Herein, low-cost nanocomposites of (Ni/Cu/N) MOF and palm pollen-derived G-graphite were prepared with different ratios namely, (1:1), (1:2), and (2:1) through a solvothermal reaction. The nanocomposites were characterized via X-ray diffraction (XRD), Scanning electron Microscopy (SEM), Fourier transform infrared (FTIR), Thermal gravimetric analysis (TGA), and, (Brunauer–Emmett–Teller) technique (BET). Electrodes have been tested as electro-catalysts for methanol-oxidation reaction (MOR) in a basic medium. As revealed from the cyclic voltammetry measurements, all electrodes exhibit a good response to MOR, being the nanocomposite with the ratio between (Ni/Cu/N) MOF and G-graphite (2:1) is the best with an oxidation peak current density of 55 mA/cm2 at a scan rate of 50 mV/s, with an onset potential of 0.35 V, and stability reaches 96 %. The electrochemical impedance spectroscopy (EIS) test showed that the ratio (2:1) has the lowest charge transfer resistance, RCT, of 5.21 Ω which confirms its higher electrochemical activity. This superior performance of the (Ni/Cu/N) MOF and G-graphite (2:1) over other reported MOF-based electrocatalysts is attributed to the synergistic effect of the (Ni/Cu/N) MOF electrocatalyst, wherein Ni and Cu provide redox electrocatalytic active sites for MOR while the G-graphite contributes towards the chemical stability and electrical conductivity of the electrode, respectively. The good activity and stability of the prepared electrodes suggest the potential use of these electrodes as electrocatalysts for MOR in direct methanol fuel cells (DMFCs).This study opens the venue for valorizing the natural wastes derived graphitic material as stable supporting material in Mof based composites electrodes for MOR.

Synthesis and characterization of 3,5-bis((2-hydroxybenzylidene)amino)-N-(2-hydroxyphenyl)benzamide and Zn(II) complex: Investigation of chromic, fluorescence and DPPH radical scavenging behaviours

Novel amido-Schiff base 3,5-bis((2-hydroxybenzylidene)amino)-N-(2-hydroxyphenyl)benzamide (2a) has been obtained by the reaction of Schiff base 1a with 2-hydroxyaniline in the presence of coupling agent N,N′-dicyclohexylcarbodiimide. Schiff base (1a) which serves as the starting compound in amide synthesis was produced from the condensation of 3,5-diaminobenzoic acid with salicylaldehyde in a 1:2 mol ratio. Tetrahedral geometry with 1:1 [M:L] stoichiometry Zn(II) complex (3a) was newly synthesized by the complexation reaction of ligand 2a with zinc(II) nitrate. 1a and 2a displayed a broad emission band at λem = 456 and 472 nm with a blue fluorescent in pure DMSO, while 3a emitted a strong greenish-blue fluorescent with the λem = 485 nm (λexc = 365 nm). The fluorescence efficiency of 1a was poor compared to the others. The λem in aqueous DMSO solution (v/v, 1:1) had ∼8–33 nm red-shift with respect to that of pure solution. The λem gave ∼1–15 nm red-shift with very low emission efficiency in acidic DMSO media. The results suggested that the aggregation caused quenching properties of 1a–3a in pure, aqueous, and acidic DMSO system with a 50 % water fraction. The fluorescence of the compounds appeared to be visibly very bright in basic DMSO media. All the compounds were also screened for antioxidant activity using UV–Vis spectroscopy. They were found to be not effective DPPH radical scavengers in DMSO.

Serum-free medium for recombinant protein expression in insect cells.

The baculovirus expression vector system (BEVS) has been widely used to produce recombinant proteins because of several advantages, such as eukaryotic post-translational modifications similar to those in mammalian cells, high expression levels and safety, and large gene capacity. Usually, insect cell culture requires 5%‒10% fetal bovine serum, which has many adverse effects, including high cost, heterogeneity between batches, complex composition, and pollution risks. Therefore, serum-free medium (SFM) is indispensable for the production of recombinant proteins in insect cell culture. Here, the most commonly used insect cell lines and three insect cell media, namely basic medium, SFM, and chemically defined medium, are summarized. The basic components of insect cell SFM are similar to those of other cells but contain special components. The components, functions, and issues of different SFM used for insect cell culture are reviewed. In recent years, some special additives have been demonstrated to increase recombinant protein expression yield and quality in BEVS, and the functions and possible mechanisms of small-molecule additives are reviewed herein. Finally, future perspectives of SFM used in BEVS for recombinant protein production are discussed.

Effects of Ni Loadings on the Structure and Morphology of Carbon Nanotubes Using Nickel Doped Iron Oxide Catalysts

AbstractIron oxide and their different doped iron oxide catalyst have been used for decades and are considered as efficient catalysts in several synthesis schemes including synthesis of carbon nanotubes. The iron oxide of the catalyst is abundant in nature, high catalytic activity at low over potentials, stability in basic media and low cost, making it environmentally and economically attractive. Nickel doped iron oxide catalyst have not been reported in the literature. Doping of nickel over iron oxide catalyst, different percentage 1 %, 5 %, 10 % and 20 % were done by impregnation method. The samples were characterized by X‐Ray powder Diffraction (XRD), Fourier‐Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive X‐ray (EDX) and Thermo Gravimetric Analysis (TGA). Nickel doped iron oxide was used as catalyst for the synthesis of carbon nanotubes (CNTs) and doping changed the morphology of carbon nanotube (CNTs). FTIR results confirmed the doping and presence of different functional groups. Chemical vapor deposition (CVD) was carried out for the synthesis of multiwall carbon nanotubes (MWCNTs) on nickel doped iron oxide catalyst for different percentage (1 %, 5 %, 10 % and 20 %) separately. CVD assembly was carried in tube furnace and the reaction was checked at two different temperature i.e 700 °C and 750 °C and using methane and compressed natural gas (CNG) as precursors. The catalyst was activated in the furnace at 800 °C for an hour. Methane and argon were used in proportion 2 : 1 inside the furnace. SEM showed formation of CNTs at 750 °C with CNG precursor. Formation of CNTs increased with increasing doping with this CNTs was confirmed by SEM.

Synthesis of New Heterocyclic Derivatives from 4-(3, 5-Dimethyl-1-phenyl-1H-pyrazol-4-ylazo)- benzoic acid

In this work pyrazolin derivatives were prepared from the diazonium chloride salt of 4-aminobenzoic acid. Azo compounds were prepared from the reaction of an ethanolic solution of sodium acetate and calculated amount of active methylene compound namely, acetyl acetone to obtain the corresponding hydrazono derivative (1). Cyclocondensation reaction of compounds (1) with hydrazine hydrate and phenyl hydrazine in boiling ethanol affording the corresponding pyrazoline-5-one derivatives of 4-aminobenzoic acid (2,3). Then compound (3) was reacted with thionyl chloride to give the corresponding acid chloride derivative(4), followed by conversion into the corresponding acid hydrazide derivative (5) carboxylic acid thiosemicarbazide (11), esters (14,15), thioesters (16,17) and amides (18,19), when treated hydrazine hydrate, thiosemicarbazide, alcohols, alkylthiol and secondary amines in dry refluxing benzene; respectively. Schiff's bases (6-8) were prepared by refluxing of compound (5) with different aldehydes and ketons, then two compounds from the Schiff's bases were cyclized with ?-mercapto acetic acid to give (9 and 10). Furthermore, 1,2,4-triazole derivative (12) have been also prepared by refluxing thiosemicarbazide derivative with sodium hydroxide solution (4%) followed acidification of the result using (10%)hydrolic acid. Moreover, a thiadiazole derivative (13) has been prepared by treatment of thiosemicarbazide derivative with concentrated sulfuric acid as cyclyzing agent. Finally, oxadiazole derivative (20) has prepared by condensation of its acid hydrazide derivative with carbon disulfide in basic medium.

NixB/Mo0.8B3 Nanorods Encapsulated by a Boron‐Rich Amorphous Layer for Universal pH Water Splitting at the Ampere Level

AbstractHeterostructured interfaces are crucial to electrocatalysts for water splitting. Herein, coral‐like multiheterostructured NixB/Mo0.8B3 (NMB) nanorods encapsulated by a boron‐rich amorphous layer are prepared for water splitting. Density‐functional theory (DFT) calculations indicate that the NMB interface adjusts the d‐band center and electronic structure of the molybdenum sites. Owing to the strong electronic coupling between Ni, Mo, and B at the heterojunction, large number of exposed catalytic active sites, as well as the special hydrophilic characteristics endowed by the surrounding amorphous layer, the NMB catalyst exhibits remarkable universal‐pH hydrogen evolution reaction (HER) activity with low overpotentials (η) of 15, 26, and 83 mV to deliver 10 mA cm−2 in basic, acid, and neutral media, respectively, and outstanding oxygen evolution reaction (OER) characteristics in the basic medium with η10 and η500 of 170 and 420 mV, respectively. The unique self‐supporting 3D hierarchical interconnected structure facilitates mass transport thus leading to high mechanical stability for 450 and 200 h in HER and OER at ≈1000 mA cm−2. More importantly, the NMB exhibits excellent performance toward overall‐water electrolysis as a bifunctional catalyst with ultralow cell voltages of 1.45/1.56/1.85 V @ 10/100/1000 mA cm−2, demonstrating the large potential in industrial water splitting applications.

Spectrofluorimetric determination of acetone in water samples with solid-phase extraction and a new benzaldehyde derivative

A new method is described for acetone (C(CH3)2O) determination in water samples. The method is based on the reaction with 4-(dimethylamino)benzaldehyde (DMAB) in dimethyl sulfoxide (DMSO) in slightly basic medium, resulting in a highly fluorescent compound with fluorescent wavelengths undisturbed by other common fluorescent compounds. Experimental conditions were optimized (reagents concentrations, reaction time) to reach optimal sensitivity. For the analysis of aqueous samples, a preconcentration step of acetone by solid-phase extraction (SPE) followed by an elution step in DMSO was optimized using Isolute ENV + columns. A highly satisfactory low detection limit of 0.014 μM (0.8 μg L−1) was achieved by combining these two steps, with a linear range from 0.048 to 5 μM and relative standard deviations between 5.7 % and 6.9 %. The protocol was validated on complex real water samples such as river water and wastewater, and our fluorimetric method with DMAB was in good agreement with the reference LC-UV method with DNPH.

The Potential of Biotic Elicitors to Increase Isoflavone Production (Pachyrhizus erosus L.) Callus

Abstract The isoflavones contained in the Pachyrhizus plant (Pachyrhizus erosus Linn) have multiple functions, including serving as raw materials for the health/pharmacology or cosmetic industries. Isoflavones are beneficial as antioxidants, and cholesterol reducers and are capable of neutralizing free radicals and delaying aging. Tissue culture techniques are widely used to produce secondary metabolite compounds. Isoflavones can be made in vitro through callus production by tissue culture. By using elicitation techniques with the addition of various glucose concentrations to the culture media (media Murashige and Skoog or Vacin and Went), it is expected to increase the quantity and quality of callus and the content of secondary metabolites (Isoflavones) in Pachyrhizus callus. The research aims to increase the production of Isoflavones in Pachyrhizus callus by adding elicitors with various concentrations of glucose. The research method used a completely randomized factorial design. Factor I: two levels of basic media: M1 (Murashige and Skoog Media) and M2 (Vacin and Went Media). Factor II: Addition of Glucose concentrations with seven levels: 0%, 5%, 10%, 15%, 20%, 25%, 30%. The plant material used was the young leaves of Pachyrhizus. The results of the study showed that (1) all formed callus exhibited compact quality; (2) the addition of 30% glucose concentration resulted in the best growth of callus; (3) the highest Isoflavone content (0.15%) was found in the callus of Pachyrhizus erosus L. due to the treatment with both MS and VW media with 20% Glucose Elicitor

Multilevel Dynamic System as Molecular Morning-After Timer.

Systems chemistry aims to develop molecular systems that display emerging properties arising from their network and absent in their individual constituents. Employing reversible chemistry under thermodynamic control represents a valuable tool for generating dynamic combinatorial libraries of interconverting molecules, which may exhibit intriguing collective behaviour. A simple dynamic combinatorial library was prepared using dithioacetal / thiol / disulfide exchanges. Because of the relative reactivities of these reversible reactions, the library constitutes a two-layer dynamic system with one layer active in an acid medium (thiol/dithioacetal exchange) and one layer active in a basic medium (thiol/disulfide exchange). This property enables the system to respond to momentary changes in acidity of the medium by activating different network regions, channeling some building blocks from one layer to another through shared thiol reagents (nodes). This momentaneous change in wiring affects the final steady state composition of the library, measured the next day, even though the event that caused it vanishes without leaving any residue. Therefore, the final composition of this dynamic system provides information about this transient past perturbation in the environment such as: when it occurred, how long it was, or how intense it was.

A structural, magnetic and colloidal stability study of uncoated and silica coated iron oxide samples prepared in two different surfactants

The discovery of new magnetic materials of interest in the biomedicine field is a relevant topic in current research. For years, our research group has been investigating the obtaining and study of nanostructured magnetic samples that behave superparamagnetically to enable their transport in living organisms. We present here a study that summarizes the structural characteristics, magnetic behavior and stability of two Fe3O4 samples synthesized by coprecipitation that were dispersed using two different surfactants (oleylamine, OL, and oleic acid, OA), and two others prepared from the previous ones by reaction with tetraethyl orthosilicate (TEOS). The relationships between the surfactant used in the synthesis, the presence of a certain maghemite (γ-Fe2O3) content, the influence of silica shell thickness and magnetic behaviour of all samples were systematically studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), Mössbauer spectroscopy and H vs. M loops. Rietveld refinements of the XRD profiles confirmed a partial oxidation of the non-silica-coated samples and FTIR spectra of the uncoated samples showed a very strong broad metal-oxygen band and additional sets of bands from the different organic chains of the two surfactants. Individual particles with a mean diameter of 7 and 9 nm were distinguished in TEM images of uncoated magnetic samples. Mössbauer data indicated the presence of non-stoichiometric magnetite in all samples, in agreement with XRD refinements. Magnetic measurements confirmed the superparamagnetic behavior of all the samples. Highest negative zeta potential values are found for the silica covered samples in both acidic and basic medium, being Fe3O4-AO@SiO2 the best suited for the purposes of its dispersibility in future applications. Low polydispersity index (PDI) values confirmed the best stability and dispersibility of all samples investigated in tetrahydrofuran (THF).

Polyoxometalate-derived anti-aggregation MoC nanoparticles for efficient hydrogen evolution in basic and acidic media

As a cost-effective alternative to Pt-based catalysts, molybdenum carbide (MoC) exhibits considerable potential for catalysing hydrogen evolution reaction (HER) in both alkaline water electrolyzers and proton exchange membrane water electrolyzers. However, achieving ampere-level current densities at low overpotentials remains challenging for MoC-based electrocatalysts. In this study, we utilized electrospinning technology followed by a subsequent heat treatment to successfully synthesize monodisperse MoC nanoparticles (approximately 4.3 nm) embedded in carbon nanofibers. The resultant self-supporting one-dimensional molybdenum carbide@nitrogen-doped carbon nanofiber (MoC-A@NCNF), prepared with polyoxometalate anion (POM) and polyvinylpyrrolidone (PVP), exhibits excellent anti-aggregation behavior. Benefiting from its high specific surface area and one-dimensional conductive network structure, the MoC-A@NCNF displays outstanding hydrogen evolution reaction (HER) performance in both 1 M KOH and 0.5 M H2SO4, achieving overpotentials of 491 mV and 568 mV at a current density of 1 A cm−2, respectively. Furthermore, it exhibits exceptional electrochemical stability during prolonged HER testing under both acidic and alkaline conditions.

DNA Probing of Peroxidase‐Mimetic Activities of Selected Manganese‐Based Nanozymes and Measurement of Antioxidant Activity for DNA Protection

AbstractThree different Mn‐based peroxidase‐mimetic nanoparticles (NPs) were synthesized as nanozymes: (i) manganese (II)‐ferrite (MnFe2O4) fabricated by co‐precipitating MnCl2.4H2O and FeCl3.6H2O; (ii) MnO2 synthesized from precipitation of MnSO4 in basic medium; (iii) manganese oxide obtained by reducing KMnO4 with tris(2‐hydroxyethyl) amine, all characterized using STEM, EDXS, FTIR and XPS techniques. These NPs acted as peroxidases, revealed by using a DNA probe, on which the damage generated by peroxidase mimetic NPs was monitored spectrophotometrically by CUPRAC and 3,3′,5,5′‐tetramethylbenzidine (TMB) methods. Results were confirmed by RP‐HPLC and voltammetry, the latter involving an AuNPs‐modified glassy carbon electrode (GCE), multi‐walled carbon nanotubes (MWCNT) and Nafion combination. Colorimetric assay with CUPRAC rather than TMB better agreed with chromatographic/voltammetric findings in detecting both peroxidase activity and DNA hazard. Mn(III)‐containing manganese oxide from permanganate reduction had stronger peroxidase activity. The proposed method demonstrated protective effects of antioxidants (morin, catechin and quercetin) against oxidative DNA damage for the first time.

Metal oxide/chalcogenide/hydroxide catalysts for water electrolysis

Electrochemical water electrolysis has gained rapid and significant interest from scientists and researchers in hydrogen production to reduce the dependency on fossil fuels and hydrogen culture recognition worldwide soon. However, developing highly efficient, economical, and durable electrocatalysts with the replacement of noble-metal-based catalysts is essential for the large-scale practical application of this strategy. Due to heightened interest in this field, a series of various bifunctional catalysts have been developed, and several articles have been published on overall water splitting (OWS). Herein, we studied an extensive kind of recent literature on designing novel metal oxide/chalcogenide/hydroxide catalysts electrocatalysts ranging from metal oxide/hydroxide and metal chalcogenides for water electrolysis. This includes the analysis of characteristics of oxygen and hydrogen evolution reactions (OER/HER) and OWS in basic, acidic, and neutral media and indices for evaluating the performance of electrocatalysts at first and then synthesis routes to obtain metal oxide/chalcogenide/hydroxide electrocatalysts are critically reviewed. Finally, the prospects of activation strategies to enhance the performance of electrocatalysts and activity descriptors are discussed. Moreover, this review will provide a route for constructing high-performance noble-metal-free electrocatalysts in sustainable water electrolysis reactions for hydrogen production.

Synthesis, Docking Study, and Antimicrobial Activity of Some New Heterocyclic Compounds Bearing Naphthalene Moiety

AbstractUpon reaction with α,β‐unsaturated nitriles (2 a–d) and/or salicylaldehyde, 3‐(naphthalen‐2‐yl)‐3‐oxopropanenitrile (1) yields pyridine derivatives 3 a–d and/or the imino chromene derivative 4. Compound 1 reacted with phenyl isothiocyanate in a basic medium to give the intermediate potassium salt 6. Upon stirring at room temperature, the intermediate 6 with some α‐halogenated compounds yielded the acyclic compounds 7, 9, 11, 13, and 15. On the other hand, refluxing intermediate 6 with the same α‐halogenated compounds in DMF in the presence of TEA afforded the corresponding thiophene derivatives 8, 10, 12, 14, and 16. The reaction of thiol 17 with hydrazine hydrate derivatives 18 a–d yielded the corresponding pyrazole derivatives 21 a–d. Compound 20 reacted with o‐phenylenediamine or o‐aminothiophenol in the presence of DMF/TEA to give the corresponding benzothiazole or benzoimidazole derivatives 27 a and 27 b, respectively. Thirty new synthesized compounds were examined for their antibacterial activity against Gram‐positive bacteria including S. aureus and B. subtilis, Gram‐negative bacteria such as P. aeruginosa and E. coli, and yeast‐like fungi like C. albicans in vitro. Compounds 15, 16, 21 d, 27 a, 27 b, exhibited the highest antibacterial activity against Gram‐positive bacteria. Molecular docking experiments were conducted to explore the binding affinities and interaction modalities of selected derivatives with the target PDB‐3cmt protein.