Electrochemical properties of modified carbon paste electrodes containing some amino derivatives of 9,10-anthraquinone

The preparation and aqueous electrochemistry of carbon paste electrodes modified by some amino-substituted 9,10-anthraquinones are reported. In all cases, the reduction processes studied by cyclic voltammetry reveal a quasi-reversible behavior. The half-wave potentials were calculated as a function of the solution pH and from the resulting potential-pH plots the formal potentials and pK _a ^′ values of different redox and acid-base couples involved at various pH ranges were evaluated. The diffusion coefficients of different anthraquinone derivatives used in paraffin oil were calculated by chronoamperometry. Received: 3 May 1999 / Accepted: 15 November 1999     

Electrochemical and Photoelectrochemical Sensing of Dihydronicotinamide Adenine Dinucleotide and Glucose Based on Noncovalently Functionalized Reduced Graphene Oxide‐Cadmium Sulfide Quantum Dots/Poly‐Nile Blue Nanocomposite

Reduced graphene oxide‐CdS quantum dots (rGO‐CdS QDs) nanocomposite was synthesized with a one‐pot and facile solvothermal strategy and characterized with X‐ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The nanocomposite modified with electropolymerized Nile blue (NB) had high electrocatalytic and photoelectrocatalytic activity toward NADH oxidation with lowering 700 mV of overvoltage compared to bare GCE. The linear response up to 200 µM was obtained for photoamperometric determination of NADH and the detection limit was 1 µM (S/N=3). Furthermore, with covalence immobilizing of glucose dehydrogenase onto the nanocomposite, the electrochemical and photoelectrochemical ability of the proposed system toward glucose biosensing was also investigated.     

Synthesis and characterization of RuO<Subscript>2</Subscript>@ZrO<Subscript>2</Subscript> core–shell nano particles as heterogeneous catalyst for oxidation of benzylic alcohols in different conditions

In this study, new RuO₂@ZrO₂ core–shell nanoparticles have been produced using simple procedure and characterized by the spectroscopic methods (XRD and HR-TEM techniques). Catalytic activity of the synthesized nano powders has been investigated in the liquid-phase selective oxidation of benzyl alcohols. Also, the effect of some parameters such as optimum weight ratio for Ru doping, catalyst, oxidant type and various solvents was studied in room temperature, reflux, ultrasound, microwave conditions and UV–vis irradiation. The catalyst exhibits excellent activity and high conversion under mild conditions. Furthermore, this reagent was recycled and reused three times in the model reaction.     

Antiviral Therapeutic Potential of Curcumin: An Update

The treatment of viral disease has become a medical challenge because of the increasing incidence and prevalence of human viral pathogens, as well as the lack of viable treatment alternatives, including plant-derived strategies. This review attempts to investigate the trends of research on in vitro antiviral effects of curcumin against different classes of human viral pathogens worldwide. Various electronic databases, including PubMed, Scopus, Web of Science, and Google Scholar were searched for published English articles evaluating the anti-viral activity of curcumin. Data were then extracted and analyzed. The forty-three studies (published from 1993 to 2020) that were identified contain data for 24 different viruses. The 50% cytotoxic concentration (CC50), 50% effective/inhibitory concentration (EC50/IC50), and stimulation index (SI) parameters showed that curcumin had antiviral activity against viruses causing diseases in humans. Data presented in this review highlight the potential antiviral applications of curcumin and open new avenues for further experiments on the clinical applications of curcumin and its derivatives.     

Simple and efficient protocol for the synthesis of benzoxazole,benzoimidazole and benzothiazole heterocycles using Fe(Ⅲ)–Schiff base/SBA-15 as a nanocatalyst

Benzimidazoles, benzoxazoles, and benzothiazoles derivatives were synthesized from condensation of aldehydes and 1,2-phenylenediamine or ortho-aminophenol or ortho-aminothiophenol in the presence of catalytic amount of Fe(Ⅲ)–Schiff base/SBA-15 in water medium. Short reaction times, good to excellent yields, easy availability, reusability, and use of an eco-friendly catalyst are some of the significant attributes of the present method.     

Laser-Induced Breakdown Spectroscopy Via the Spatially Resolved Technique Using Non-Gated Detector

We present a simple setup for laser-induced breakdown spectroscopy using the spatially resolved technique (SRLIBS). We show that, without any need for time-gated ICCD and pulse generator, the signal-to-background ratio is enhanced. We develop a homemade spectrograph with a movable slit located at its entrance to detect different parts of the plasma emission. For optimizing the position of the slit, we use the shadowgraphy technique to study the plasma expansion. In this low cost setup, with nanosecond laser pulses, we perform SRLIBS experiments on the plasma induced in air and iron. Our results show that the signal-to-background ratio for iron and air is enhanced up to 15 and 8 times, respectively.