Polarographic reduction of maleic anhydride, maleate and fumerate in pyridine

Maleic and fumaric acids in pyridine show only the reduction behaviour of the pyridinium ion, which is produced when any Bronsted acid of aqueous pKa less than ca 9 is dissolved in pyridine. The diethyl esters each show two one-electron waves, which pattern is characteristic for the electrochemical reduction of double bonds in proton-poor solvents. Maleic anhydride, which is a dihydrofuran, shows initially a single wave at a potential considerably more positive than the reduction potential of diethyl maleate; with time, a second maleic anhydride wave appears and grows at the expense of the first wave. The anhydride slowly reacts with the trace of moisture in the solvent to form maleic acid, which behaves as already indicated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33366/1/0000764.pd

Nature of the surface compounds and reactions observed on graphite electrodes

The nature and composition of the surface of pyrolytic graphite and the consequent possible effects, when the material is used as an electrode, are considered on the basis of the structure of the graphite and of the handling and/or treatment to which the electrodes may have been exposed. Because of the relatively limited studies on pyrolytic graphite, certain aspects of the behavior of other types of graphite and of carbon are discussed owing to their probable relation to the behavior of pyrolytic graphite. An appreciation of the constitution of graphite electrodes in terms of surface compounds and of the possible interaction of these compounds with solution species or their reaction products, when the electrodes are used in electrolytic processes, is essential for their optimum utilization. The main areas surveyed are the structure of pyrolytic graphite as related to electrode usage, types of possible compound formation, electrolytic behavior of graphite electrodes, and formation of carbon-oxygen and related organic surface compounds with the resulting influence on adsorption and other phenomena.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22000/1/0000413.pd

Effect of antifungal agents on indwelling voice prosthetic biofilms

Rehabilitating the lost voice of laryngectomy patients by insertion of a silicone rubber voice prosthesis is now generally considered to be superior to any other form of substitute voice production. However, a drawback of these implants is the rapid colonization by a mixed biofilm of bacteria and yeasts, mainly Candida species, leading to failure and frequent exchange of the implant. A strategy frequently applied by otolaryngologists is oropharyngeal yeast decontamination by using antifungal agents, despite the fact that there is no compelling evidence that prescription of antifungal agents will prolong the lifetime of voice prostheses. Moreover, the prophylactic use of antifungal agents contributes to the development of resistant strains. Alternative approaches to prolonging the lifetime of silicone rubber voice prostheses may be found in modification of the silicone rubber surface of the implant, diet supplementation with active, probiotic bacteria, or salivary substitutes with synthetic antimicrobial peptides.</p

Understanding the electromagnetic interaction of metal organic framework reactants in aqueous solution at microwave frequencies

Preparation of metal organic frameworks (MOFs) via microwave heating is becoming increasingly popular due to reduced reaction times and enhanced control of MOF particle size. However, there is little understanding about the detailed interaction of the electric field portion of the wave with reactants during the synthesis of MOFs. In order to overcome this lack of fundamental understanding, information about the dielectric properties of the reactants is required. In this work the dielectric constants (ε′) and loss factors (ε′′) of benzene-1,4-dicarboxylic acid (H2BDC; also known as terephthalic acid) and a number of M(III) (M = metal) salts dissolved in deionized water were measured as a function of frequency, temperature and concentration and with varying anions and cations. Dielectric data confirm the aqueous M(III) salts to be strong microwave absorbers, particularly at 915 MHz. M(III) salts with mono-anionic ligands (for example chlorides and nitrates) exhibit higher losses than di-anionic salts (sulfates) demonstrating that the former are heated more effectively in an applied microwave field. Of the M(III) salts containing either singly- or doubly-charged anions, those containing Fe(III) have the highest loss indicating that they will heat more efficiently than other M(III) salts such as Cr(III) and Al(III). Interestingly, H2BDC exhibits little interaction with the electric field at microwave frequencies

Molecular epidemiology and evolutionary trajectory of emerging echovirus 30, Europe

In 2018, an upsurge in echovirus 30 (E30) infections was reported in Europe. We conducted a large-scale epidemiologic and evolutionary study of 1,329 E30 strains collected in 22 countries in Europe during 2016-2018. Most E30 cases affected persons 0-4 years of age (29%) and 25-34 years of age (27%). Sequences were divided into 6 genetic clades (G1-G6). Most (53%) sequences belonged to G1, followed by G6 (23%), G2 (17%), G4 (4%), G3 (0.3%), and G5 (0.2%). Each clade encompassed unique individual recombinant forms; G1 and G4 displayed >= 2 unique recombinant forms. Rapid turnover of new clades and recombinant forms occurred over time. Clades G1 and G6 dominated in 2018, suggesting the E30 upsurge was caused by emergence of 2 distinct clades circulating in Europe. Investigation into the mechanisms behind the rapid turnover of E30 is crucial for clarifying the epidemiology and evolution of these enterovirus infections.Molecular basis of virus replication, viral pathogenesis and antiviral strategie