Electrolytic Cell Design to Simulate the Electrochemical Skin Response

Small fiber peripheral neuropathy is an early complication of diabetes. Electric skin response to some stimulus, as electrochemical skin conductance ECS, is a promising route in the early follow‐up of such diseases. It is related to sweat gland innervations and their permeability to chlorides and protons; it is non‐invasive, quantitative and reproducible. In routine clinical use, it could allow to better adapt the treatments and improve the adhesion for preventing pathological progress, thus reducing colossal healthcare costs. To optimize the measurements and understand the electrochemical behavior of electrodes, an original electrolytic cell was designed in lab scale. Thereby, an electrolyte is chosen to mimic sweat composition. For achieving currents range of ESC in vivo measurements, the original idea was to play on electrolyte viscosity by adding sucrose. In this paper, the novel electrolytic lab cell is presented with its limiting kinetics processes. A model of chloride migration to the anode and global electric model dedicated to the cell are proposed. Cell parameters are thoroughly studied, e. g. the resistance, which is equivalent to the inverse of ESC, by exploiting the models and through in vitro experiments, with protocols focusing on reproducibility. This original approach establishes, inter alia, an important result: the resistance is accurately retrieved using linear voltammetry, whereas single voltage measurement fails notably and is, therefore, unsatisfactory.     

Efficient Synthesis of Differentiated syn‐1,2‐Diol Derivatives by Asymmetric Transfer Hydrogenation–Dynamic Kinetic Resolution of α‐Alkoxy‐Substituted β‐Ketoesters

Asymmetric transfer hydrogenation was applied to a wide range of racemic aryl α‐alkoxy‐β‐ketoesters in the presence of well‐defined, commercially available, chiral catalyst Ru^II–(N‐p‐toluenesulfonyl‐1,2‐diphenylethylenediamine) and a 5:2 mixture of formic acid and triethylamine as the hydrogen source. Under these conditions, dynamic kinetic resolution was efficiently promoted to provide the corresponding syn α‐alkoxy‐β‐hydroxyesters derived from substituted aromatic and heteroaromatic aldehydes with a high level of diastereoselectivity (diastereomeric ratio (d.r.)>99:1) and an almost perfect enantioselectivity (enantiomeric excess (ee)>99 %). Additionally, after extensive screening of the reaction conditions, the use of Ru^II‐ and Rh^III‐tethered precatalysts extended this process to more‐challenging substrates that bore alkenyl‐, alkynyl‐, and alkyl substituents to provide the corresponding syn α‐alkoxy‐β‐hydroxyesters with excellent enantiocontrol (up to 99 % ee) and good to perfect diastereocontrol (d.r.>99:1). Lastly, the synthetic utility of the present protocol was demonstrated by application to the asymmetric synthesis of chiral ester ethyl (2S)‐2‐ethoxy‐3‐(4‐hydroxyphenyl)‐propanoate, which is an important pharmacophore in a number of peroxisome proliferator‐activated receptor α/γ dual agonist advanced drug candidates used for the treatment of type‐II diabetes.     

Enantioselective Synthesis of Homologous Methyl-Substituted Bicyclic Enones Through Michael-Type Alkylation of Chiral Imines

The preparation of 4a-methyl-substituted bicyclic enones in high enantiomeric purity is described, involving a Michael alkylation of (R)- or (S)-1-phenylethyl imines of the corresponding (±)-2-methylcyclopentanone, 2-methyl-cyclohexanone, 2-methylcycloheptanone, and 2-methylcyclooctanone with methyl vinyl ketone.     

Evidence of C non-covalent isotope effects obtained by quantitative C nuclear magnetic resonance spectroscopy at natural abundance during normal phase liquid chromatography

Quantitative isotopic ¹³C NMR at natural abundance has been used to determine the site-by-site ¹³C/¹²C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global ¹³C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present.     

Circulatory bubble dynamics: From physical to biological aspects

Bubbles can form in the body during or after decompression from pressure exposures such as those undergone by scuba divers, astronauts, caisson and tunnel workers. Bubble growth and detachment physics then becomes significant in predicting and controlling the probability of these bubbles causing mechanical problems by blocking vessels, displacing tissues, or inducing an inflammatory cascade if they persist for too long in the body before being dissolved. By contrast to decompression induced bubbles whose site of initial formation and exact composition are debated, there are other instances of bubbles in the bloodstream which are well-defined. Gas emboli unwillingly introduced during surgical procedures and ultrasound microbubbles injected for use as contrast or drug delivery agents are therefore also discussed. After presenting the different ways that bubbles can end up in the human bloodstream, the general mathematical formalism related to the physics of bubble growth and detachment from decompression is reviewed. Bubble behavior in the bloodstream is then discussed, including bubble dissolution in blood, bubble rheology and biological interactions for the different cases of bubble and blood composition considered.     

Equidistant hypersurfaces of the bidisk

The following are notes on the geometry of the bidisk, H ² × H ². In particular, we examine the properties of equidistant surfaces in the bidisk.