Thermal decompositions of dinitropyridyl and dinitrothienyl dithiocarbamates and t-butyl trithiocarbonates

The title compounds on heating cyclized to yield 7-nitro-1,3-dithiolo[4,5-c]pyridin-2-one (III), 6-nitro-1,3-dithiolo[2,3-c]pyridin-2-one (VIIa), 6-nitrothieno[2,3-d]-1,3-dithiol-2-one (XIVa) and 6-nitrothteno[2,3-d]-1,3-dithiole-2-thione (XIVb).     

Ionic liquids based upon metal halide/substituted quaternary ammonium salt mixtures

The synthesis of ionic liquids based upon functionalized quaternary ammonium salts and metal salts of zinc, tin, or iron is demonstrated. The freezing point of these ionic liquids was studied as a function of the quaternary ammonium cation. The complex anions were identified and quantified using mass spectrometry and potentiometry. It is shown that the primary zinc anion is Zn(2)Cl(5)(-) with Zn(3)Cl(7)(-) becoming more abundant in more Lewis basic solutions. Similar results were observed for ionic liquids containing SnCl(2). The surface tension was also measured and was used to explain the high viscosity of the ionic liquids in terms of the large ion:hole size ratio and the small probability of finding a hole of suitable dimensions adjacent to a given ion to permit movement. The phase behavior of a variety of quaternary ammonium halides/ZnCl(2) mixtures is characterized and it is shown that the depression of freezing point is related to the increase in size of the component ions.     

Dye adsorbed few-layer thick Ti3C2Tx-MXenes for direct electrochemical detection of CD44 proteins

The direct electrochemical detection of cancer biomarkers using single single-component platforms is challenging. Herein, we propose constructing an efficient screen-printed electrode (SPE) based platform for selective detection of CD44 proteins, a non-kinase transmembrane glycoprotein. A sensing platform, MB-MX/HA/SPE, was developed by incorporating few-layered Ti₃C₂T_x nanosheets pre-loaded with methylene blue (MB) dye. The nanosheets were subsequently immobilized with hyaluronic acid (HA), which served as a ligand for the specific recognition of CD44. The simple electrode configuration and the highly conductive Ti₃C₂T_x facilitated the electrochemical oxidation of MB, generating a reference SWV signal that declined proportionally with the increasing concentration of CD44 owing to ligand (HA)-protein interaction. The sensor could register a sensitive inhibition response in the concentration range of 0.1 to 7.25 ng.mL⁻¹ with a detection limit of 1.2×10⁻² ng.mL⁻¹ for CD44 proteins. Moreover, the synergistic combination of the highly conductive/adsorptive Ti₃C₂T_x nanosheets and hyaluronic acid (HA) led to strong antifouling characteristics even in the presence of other common proteins, such as bovine serum albumin (BSA), haemoglobin (Ig), immunoglobulin G (IgG), prostate-specific antigen (PSA), and neuron-specific enolase (NSE). The proposed strategy eliminates the need for additional components in the electrode modification procedure. In addition, incorporating MXenes as electrode material paves the way for developing sensitive biosensors with prospective applications in cancer diagnosis.     

Incorporation of NH<Subscript>4</Subscript>NO<Subscript>3</Subscript> into MC-PVA blend-based polymer to prepare proton-conducting polymer electrolyte films

Proton-conducting solid polymer blend electrolytes based on methylcellulose-polyvinyl alcohol:ammonium nitrate (MC-PVA:NH₄NO₃) were prepared by the solution cast technique. The structural and electrical properties of the samples were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electrical impedance (EI) spectroscopy. The shifting and change in the intensity of FTIR bands of the electrolyte samples confirm the complex formation between the MC-PVA polymer blend and the NH₄NO₃ added salt. The observed broadening in the XRD pattern of the doped samples reveals the increase of the amorphous fraction of polymer electrolyte samples. The increase in electrical conductivity of polymer electrolyte samples with increasing salt concentration attributed to the formation of charge-transfer complexes, and to increase in the amorphous domains. A maximum ionic conductivity of about 7.39 × 10^?5 S cm^?1 was achieved at room temperature for the sample incorporating 20 wt% of NH₄NO₃. The DC conductivity of the present polymer system exhibits Arrhenius-type dependence with temperature. The decrease in the values of activation energies with increasing salt concentration indicates the ease mobility of ions. The decrease in dielectric constant with increasing frequency was observed at all temperatures. Optical properties such as absorption edge, optical band gap, and tail of localized state were estimated for polymer blend and their electrolyte films. It was found that the optical band gap values shifted towards lower photon energy from 6.06 to 4.75 eV by altering the NH₄NO₃ salt content.     

Quantum eraser for three-slit interference

It is well known that in a two-slit interference experiment, if the information, on which of the two paths the particle followed, is stored in a quantum path detector, the interference is destroyed. However, in a set-up where this path information is ‘erased’, the interference can reappear. Such a set-up is known as a quantum eraser. A generalization of quantum eraser to a ‘three-slit’ interference is theoretically analysed. It is shown that three complementary interference patterns can arise out of the quantum erasing process.     

Anthracene and Pyrene Biodegradation Performance of Marine Sponge Symbiont Bacteria Consortium

Every petroleum-processing plant produces sewage sludge containing several types of polycyclic aromatic hydrocarbons (PAHs). The degradation of PAHs via physical, biological, and chemical methods is not yet efficient. Among biological methods, the use of marine sponge symbiont bacteria is considered an alternative and promising approach in the degradation of and reduction in PAHs. This study aimed to explore the potential performance of a consortium of sponge symbiont bacteria in degrading anthracene and pyrene. Three bacterial species (Bacillus pumilus strain GLB197, Pseudomonas stutzeri strain SLG510A3-8, and Acinetobacter calcoaceticus strain SLCDA 976) were mixed to form the consortium. The interaction between the bacterial consortium suspension and PAH components was measured at 5 day intervals for 25 days. The biodegradation performance of bacteria on PAH samples was determined on the basis of five biodegradation parameters. The analysis results showed a decrease in the concentration of anthracene (21.89%) and pyrene (7.71%), equivalent to a ratio of 3:1, followed by a decrease in the abundance of anthracene (60.30%) and pyrene (27.52%), equivalent to a ratio of 2:1. The level of pyrene degradation was lower than that of the anthracene due to fact that pyrene is more toxic and has a more stable molecular structure, which hinders its metabolism by bacterial cells. The products from the biodegradation of the two PAHs are alcohols, aldehydes, carboxylic acids, and a small proportion of aromatic hydrocarbon components.     

Effect of He+ and H+ ion irradiation on polystyrene films probed by NIR photothermal deflection spectroscopy

+ and H⁺ ions. Photothermal deflection spectroscopy (PDS) technique was used to record the absorption spectrum in the wavelength range 1.20 μm to 2.0 μm. The evolution of the various overtone and combination bands occurring in this range has been related to the changes taking place in the polystyrene structure. Received: 1 September 1998 / Accepted: 20 November 1998 / Published online: 24 February 1999     

Selected Class of Enamides Bearing Nitro Functionality as Dual-Acting with Highly Selective Monoamine Oxidase-B and BACE1 Inhibitors

A small series of nitro group-bearing enamides was designed, synthesized (NEA1–NEA5), and evaluated for their inhibitory profiles of monoamine oxidases (MAOs) and β-site amyloid precursor protein cleaving enzyme 1 (β-secretase, BACE1). Compounds NEA3 and NEA1 exhibited a more potent MAO-B inhibition (IC₅₀ value = 0.0092 and 0.016 µM, respectively) than the standards (IC₅₀ value = 0.11 and 0.14 µM, respectively, for lazabemide and pargyline). Moreover, NEA3 and NEA1 showed greater selectivity index (SI) values toward MAO-B over MAO-A (SI of >1652.2 and >2500.0, respectively). The inhibition and kinetics studies suggested that NEA3 and NEA1 are reversible and competitive inhibitors with K_i values of 0.013 ± 0.005 and 0.0049 ± 0.0002 µM, respectively, for MAO-B. In addition, both NEA3 and NEA1 showed efficient BACE1 inhibitions with IC₅₀ values of 8.02 ± 0.13 and 8.21 ± 0.03 µM better than the standard quercetin value (13.40 ± 0.04 µM). The parallel artificial membrane permeability assay (PAMPA) method demonstrated that all the synthesized derivatives can cross the blood–brain barrier (BBB) successfully. Docking analyses were performed by employing an induced-fit docking approach in the GLIDE module of Schrodinger, and the results were in agreement with their in vitro inhibitory activities. The present study resulted in the discovery of potent dual inhibitors toward MAO-B and BACE1, and these lead compounds can be fruitfully explored for the generation of newer, clinically active agents for the treatment of neurodegenerative disorders.     

Antimicrobial Activity of Dihydroisocoumarin Isolated from Wadi Lajab Sediment-Derived Fungus Penicillium chrysogenum: In Vitro and In Silico Study

Antibiotic resistance is considered a major health concern globally. It is a fact that the clinical need for new antibiotics was not achieved until now. One of the most commonly prescribed classes of antibiotics is β-Lactam antibiotics. However, most bacteria have developed resistance against β-Lactams by producing enzymes β-Lactamase or penicillinase. The discovery of new β-Lactamase inhibitors as new antibiotics or antibiotic adjuvants is essential to avoid future catastrophic pandemics. In this study, five dihydroisocoumarin: 6-methoxy mellein (1); 5,6-dihydroxymellein (2); 6-hydroxymellein (3); 4-chloro-6-hydroxymellein (4) and 4-chloro-5,6-di-hydroxymellein (5) were isolated from Wadi Lajab sediment-derived fungus Penicillium chrysogenum, located 15 km northwest of Jazan, KSA. The elucidation of the chemical structures of the isolated compounds was performed by analysis of their NMR, MS. Compounds 1–5 were tested for antibacterial activities against Gram-positive and Gram-negative bacteria. All of the compounds exhibited selective antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Bacillus licheniformis except compound 3. The chloro-dihydroisocoumarin derivative, compound 4, showed potential antimicrobial activities against all of the tested strains with the MIC value between 0.8–5.3 μg/mL followed by compound 5, which exhibited a moderate inhibitory effect. Molecular docking data showed good affinity with the isolated compounds to β-Lactamase enzymes of bacteria; NDM-1, CTX-M, OXA-48. This work provides an effective strategy for compounds to inhibit bacterial growth or overcome bacterial resistance.