Selective Indicator Reaction for Kinetic Determination of Traces of Manganese(II), Ribavirin and Tiazofurin

 In this work it was established that, in the presence of ammonium carbonate, traces of manganese(II) catalyse the oxidation of Nile Blue A by hydrogen peroxide, which enables its kinetic determination in the concentration range from 6.6 to 65.9 ng cm⁻³, the detection limit being 8.0 × 10⁻² ng cm⁻³. Antiviral/antitumour substances modify the catalytic activity of manganese(II): 1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide, ribavirin, increases the catalytic effect of manganese(II), while 2-β-D-ribofuranosyl-thiazole-4-carboxamide, tiazofurin, acts as an inhibitor. On the basis of these effects, a kinetic method for determining ribavirin concentrations from 0.5 × 10⁻¹ to 4.0 × 10⁻¹ μg cm⁻³ and tiazofurin concentrations from 0.3 to 2.6 μg cm⁻³ is proposed. The kinetics of the indicator reaction were studied in the presence of the substances examined, the kinetic equations established, and the constants of the corresponding reaction rates calculated. The effect of temperature on these reactions was also investigated. The method was applied to the determination of manganese(II) in mineral water and ribavirin in pharmaceutical preparations. Received December 16, 1999. Revision June 6, 2000.     

Synthesis and Structures of New Enaminones

Two isomeric enaminones were obtained by reaction of ethyl 2-hydroxy-4-(4-hydroxy-6-methyl2H-pyran-2-on-3-yl)-4-oxo-2-butenoate (1) and amines (aniline, benzylamine, butylamine and tyramine) in ethanol. The structures of isomers were studied by ¹³C and ¹H NMR spectra, whereas in the case of isomers 2b, 3a, and 4a (Scheme 1), the crystal structures have been determined by single crystal X-ray diffractometry. The compounds 2b and 3a exist in the solid state as N–C=C–C=O, whereas 4a is in the N–C=C–C–OH tautomeric form (Scheme 2, form A and B, respectively). All three structures exhibit very short intramolecular hydrogen bonds of O–H···O [in the range 2.396(3) – 2.448(3) Å] and N–H···O [in the range 2.580(5) – 2.679(3) Å] type, that are reinforced by delocalization. The crystal structures are in addition stabilized by C–H···O weak hydrogen bonds. In 2b and 3a, the discrete dimers are formed by eight-membered ring containing hydrogen bonds; in 4a, the infinite chains along [1 0 1] direction are formed.     

A 1:2 complex of mercury(II) chloride with 1,3‐imidazole‐2‐thione

The Hg atom in the title monomeric complex, di­chloro­bis(3‐imidazolium‐2‐thiol­ato‐S)­mercury(II), [HgCl₂(C₃H₄N₂S)₂], is four‐coordinate having an irregular tetrahedral geometry composed of two Cl atoms [Hg—Cl 2.622 (2) and 2.663 (2) Å] and two thione S atoms [Hg—S 2.445 (2) and 2.462 (2) Å]. The monodentate thione ligand adopts a zwitterionic form and exists as the 3‐imidazolium‐2‐thiol­ate ion. The bond angle S1—Hg—S2 of 130.87 (8)° has the greatest deviation from ideal tetrahedral geometry. Intermolecular hydrogen bonds between two of the four N—H groups and one of the Cl atoms [3.232 (8) and 3.238 (7) Å] stabilize the crystal structure, while the other two N—H groups contribute through the formation of N—H?Cl intramolecular hydrogen bonds with the other Cl atom [3.121 (7) and 3.188 (7) Å].     

Effects of Dietary α-Linolenic Acid Treatment and the Efficiency of Its Conversion to Eicosapentaenoic and Docosahexaenoic Acids in Obesity and Related Diseases

The essential fatty acid alpha-linolenic acid (ALA) is present in high amounts in oils such as flaxseed, soy, hemp, rapeseed, chia, and perilla, while stearidonic acid is abundant in echium oil. ALA is metabolized to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by desaturases and elongases in humans. The conversion of ALA to EPA and DHA is limited, and these long-chain n−3 polyunsaturated fatty acids (PUFAs) are mainly provided from dietary sources (fish and seafood). This review provides an overview of studies that explored the effects of dietary supplementation with ALA in obesity and related diseases. The obesity-associated changes of desaturase and elongase activities are summarized, as they could influence the metabolic conversion of ALA. Generally, supplementation with ALA or ALA-rich oils leads to an increase in EPA levels and has no effect on DHA or omega-3 index. According to the literature data, stearidonic acid could enhance conversion of ALA to long-chain n−3 PUFA in obesity. Recent studies confirm that EPA and DHA intake should be considered as a primary dietary treatment strategy for improving the omega-3 index in obesity and related diseases.     

Breaking Barriers in Emerging Biomedical Applications

The recent global COVID-19 pandemic has revealed that the current healthcare system in modern society can hardly cope with the increased number of patients. Part of the load can be alleviated by incorporating smart healthcare infrastructure in the current system to enable patient’s remote monitoring and personalized treatment. Technological advances in communications and sensing devices have enabled the development of new, portable, and more power-efficient biomedical sensors, as well as innovative healthcare applications. Nevertheless, such applications require reliable, resilient, and secure networks. This paper aims to identify the communication requirements for mass deployment of such smart healthcare sensors by providing the overview of underlying Internet of Things (IoT) technologies. Moreover, it highlights the importance of information theory in understanding the limits and barriers in this emerging field. With this motivation, the paper indicates how data compression and entropy used in security algorithms may pave the way towards mass deployment of such IoT healthcare devices. Future medical practices and paradigms are also discussed.     

ATP bioluminescence method: tool for rapid screening of organic and microbial contaminants on deteriorated mural paintings

Abstract

The extent of the microbial contamination of the seventeenth-century wall paintings in the nave of the old Church of the Holy Ascension (Veliki Kr?imir, Serbia) was evaluated via newly implemented ATP bioluminescence method, and traditional cultivation-based method, utilising commercially available dip slides. To assess the validity of ATP, as a biomarker for rapid detection of mural surface contamination, obtained zones of cleanliness values, in range from 1.0 to 5.3, were compared to documented total microbial counts, ranging between seven and 247 CFU/cm². Small coefficients of determination, 0.0106–0.0385, suggest poor correlation between microbial counts and surface ATP levels; however, zones of cleanliness values are of great help in determining the high points of contamination, aka ‘hotspots’, which should be given special attention during sampling and investigation using other methods. In addition, various aspects of the possible implementation of the ATP bioluminescence method in an integrated system of wall painting conservation are discussed.     

DNA binding and antitumor activities of zinc(II) complexes with some S-alkenyl derivatives of thiosalicylic acid

Transition Metal Chemistry - Two zinc(II) complexes with S-alkenyl derivatives of thiosalicylic acid as ligands have been synthesized and characterized by microanalysis, IR, 1H and 13C NMR...     

A One-Pot Synthesis and Structure Determination of 3-(1-Phenyl-5-p-tolylpyrazol-3-yl)-2-p-tolylindole Ethanol Solvate

The Fischer indolization afforded the title compound C₃₁H₂₅N₃·C₂H₅OH as the major product in the reaction of 1,5-di(p-tolyl)pentane-1,3,5-trione with phenylhydrazine hydrochloride in ethanol. The structure assignment of this novel pyrazolylindole derivative is based on the data of elemental analysis, IR, ¹H NMR, and ¹³C NMR spectroscopy. The structure is also confirmed by means of X-ray crystallography. The molecule crystallizes in the orthorhombic space group P 2₁2₁2₁, with a = 10.298(2), b = 14.984(5), c = 18.133(3) A, Z = 8, V = 2798.0(12) A³. The absolute structure has been determined. The ethanol molecule forms intermolecular hydrogen bonds with the pyrazole and indole nitrogen atoms.     

Inhibition of methicillin resistant Staphylococcus aureus by a plasma needle

In numerous recent papers plasma chemistry of non equilibrium plasma sources operating at atmospheric pressure has been linked to plasma medical effects including sterilization. In this paper we present a study of the effectiveness of an atmospheric pressure plasma source, known as plasma needle, in inhibition of the growth of biofilm produced by methicillin resistant Staphylococcus aureus (MRSA). Even at the lowest powers the biofilms formed by inoculi of MRSA of 10⁴ and 10⁵ CFU have been strongly affected by plasma and growth in biofilms was inhibited. The eradication of the already formed biofilm was not achieved and it is required to go to more effective sources.