Backside SERS studies of inhibitor transport through polyelectrolyte films on Ag-substrates

In situ backside surface enhanced Raman spectroscopy (in situ-SERS) was newly employed for the study of the transport of inhibiting molecules through a polymer film. The barrier properties of layer-by-layer polyelectrolyte films (PE) composed of polyacrylic acid and polyallylamine hydro-chloride layers on Ag-surfaces were compared between untreated, thermally crosslinked, and Ag-nanoparticles containing samples. IB-SERS enabled the study of the transport of 2-mercaptobenzimidazole (MBI) as an inhibitor through the film. Water barrier properties of the treated PE films determined by Electrochemical Impedance Spectroscopy were correlated to the MBI diffusion kinetics. The PE stability against MBI diffusion and thermal treatment was analyzed by Infra-Red Reflection Absorption Spectroscopy (IRRAS). IRRAS showed that the thermally treated PE films formed chemical crosslinking via amide bonds and lowered the diffusion of water and the water uptake in the films. Moreover, the MBI diffusion kinetics can be followed by means of SERS. However, MBI adsorption at the PE film/metal interface was not detected after the heat treatment. In this case the adsorbed PE on the Ag surface was not substituted by the competing adsorption of MBI. Moreover, the presence of Ag-nanoparticles in the film decelerated MBI diffusion to the SERS substrate due to the trapping effect of MBI molecules.     

Phomachalasins A-D, 26-oxa[16] and [15]cytochalasans produced by Phoma exigua var. exigua, a potential mycoherbicide for Cirsium arvense biocontrol

Phoma exigua var. exigua, a fungal pathogen isolated from Cirsium arvense and Sonchus arvensis, proposed as a biocontrol agent of this noxious perennial weeds, produces in liquid and solid cultures different phytotoxic metabolites with potential herbicidal activity. The phytotoxic cytochalasins B, F, Z2, and Z3 and deoxaphomin were previously identified together with p-hydroxybenzaldehyde. Using spectroscopic methods, four new cytochalasins, termed phomachalasins A-D, were isolated and characterized as three new closely related 26-oxa[16] and one new [15]cytochalasans. They belong to a new subgroup of cytochalasans bearing a 1,2,3,4,6,7-hexasubstituted bicycle[3.2.0]heptene joined to the macrocyclic ring. None of the four new metabolites showed phytotoxic or antimicrobial activity. The lack of both phytotoxic and antimicrobial activities showed by all phomachalasins A-D was probably due to the strong modification of both functionalities and conformational freedom of the macrocyclic ring caused by its junction with the bulky and quite rigid new bicycle, namely bicycle[3.2.0]heptene.     

Localization/delocalization of charges in bay-linked perylene bisimides

The copper-mediated Ullmann coupling of 1,7-dibromoperylene bisimides afforded structurally perfect singly-linked perylene bisimide (PBI) arrays, whilst the homo-coupling of 1,12-dibromoperylene bisimides gave doubly-linked and triply-linked diperylene bisimides. The interactions of three bay-linked diperylene bisimides that differed in their linkage (singly, doubly, and triply) were investigated in their neutral and reduced forms (mono-anion to tetra-anion). UV/Vis absorption and fluorescence spectroscopy revealed different degrees of interaction, which was explained by exciton coupling and conjugation effects. The electrochemical properties and spectroelectrochemistry also showed quite-different degrees of PBI interactions in the reduced mixed-valence species, which was apparent by the observation of CT bands. The interpretation of the experimental findings was supported by spin-restricted and -unrestricted DFT and time-dependent TD-DFT calculations with the long-range-corrected CAM-B3LYP functional. Accordingly, the degree of interaction in both the neutral and reduced forms of the bay-linked PBIs was qualitatively in the order doubly linked相似文献   

Slippage mutation rates in 15 autosomal short tandem repeat loci for forensic purposes in a Southeastern Brazilian population

Well‐defined estimates of mutation rates in highly polymorphic tetranucleotide STR loci are a prerequisite for human identification in genetics laboratory routines useful for civil and criminal investigations. Studying 15 autosomal STR loci of forensic interest (CSF1PO, D2S1338, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D19S433, D21S11, FGA, TH01, TPOX, and vWA), we detected 193 slippage mutations (189 one‐step and four two‐step mutations) in 148 875 parent‐child allelic transfers from 5171 paternity cases with true biological relationship (15 096 individuals; 4754 trios and 417 duos; 9925 meiosis) from the state of São Paulo, a very representative population of Brazil. The overall mutation rate was 1.3 × 10^?3 and the highest rates were observed at loci vWA (2.8 × 10^?3), FGA and D18S51 (2.7 × 10^?3 for both), while loci TH01 and TPOX did not present any mutations. The mean slippage mutation rate of paternal origin (1.8 × 10^?3) was six times higher than that observed for maternal origin (0.3 × 10^?3).     

Fractional volume integration in two-dimensional NMR spectra: CAKE, a Monte Carlo approach

Quantitative information from multi-dimensional NMR experiments can be obtained by peak volume integration. The standard procedure (selection of a region around the chosen peak and addition of all values) is often biased by poor peak definition because of peak overlap. Here we describe a simple method, called CAKE, for volume integration of (partially) overlapping peaks. Assuming the axial symmetry of two-dimensional NMR peaks, as it occurs in NOESY and TOCSY when Lorentz-Gauss transformation of the signals is carried out, CAKE estimates the peak volume by multiplying a volume fraction by a factor R. It represents a proportionality ratio between the total and the fractional volume, which is identified as a slice in an exposed region of the overlapping peaks. The volume fraction is obtained via Monte Carlo Hit-or-Miss technique, which proved to be the most efficient because of the small region and the limited number of points within the selected area. Tests on simulated and experimental peaks, with different degrees of overlap and signal-to-noise ratios, show that CAKE results in improved volume estimates. A main advantage of CAKE is that the volume fraction can be flexibly chosen so as to minimize the effect of overlap, frequently observed in two-dimensional spectra.     

The effect of key process parameters on crystallographic texture and magnetic properties of PrFeB HD sintered magnets produced using high-energy milling

A combination of hydrogen decrepitation and planetary ball milling has been used to produce sintered Pr₁₆Fe₇₆B₈ magnets. The effects of key process parameters and texture have been studied. The alignment degree (cos Θ) has been investigated by X-ray pole figure analysis using the (0 0 4) reflection. Magnets prepared from the alloy decrepitated for 3.6 ks and milled for 1.8 ks exhibited a low degree of crystal alignment (0.71±0.02) due to polycrystalline particles. Increasing the milling time to 4.5ks has led to an improvement in cos Θ to 0.84±0.02. This has been ascribed to the smaller particle size with a narrower size distribution as well as a more favorable particle shape for orientation. Superior alignment degree (cos Θ=0.88±0.02) has been achieved for the sintered magnet from the alloy decrepitated for 120 s and milled for 5.4 ks. This particular processing condition has led to a magnet with (BH)_max=250±5 kJ m⁻³, value found in magnets produced using roller ball milling, with the advantage of a reduced milling time (about 90%).     

Phenylalanine Butyramide Is a New Cosmetic Ingredient with Soothing and Anti-Reddening Potential

Human skin is colonized by diverse commensal microbes, making up the skin microbiota (SM), contributing to skin integrity and homeostasis. Many of the beneficial effects aroused by the SM are exerted by microbial metabolites such as short-chain fatty acids (SCFAs), including butyric acid. The SCFAs can be used in cosmetic formulations against skin diseases to protect SM by preserving and/or restoring their natural balance. Unpleasant sensorial properties and unfavorable physico-chemical properties of butyrate strongly limit its cosmetic use. In contrast, some butyrate derivatives, including phenylalanine butyramide (C₁₃H₁₈N₂O₂, FBA), a solid form of butyric acid, are odorless while retaining the pharmacokinetic properties and safety profile of butyric acid. This study assessed the FBA’s permeation across the skin and its soothing and anti-reddening potential to estimate its cosmetic application. The dosage method used to estimate FBA’s levels was validated to be sure of analytical results. The FBA diffusion tests were estimated in vitro using a Franz-type vertical diffusion cell. The soothing action was evaluated in vivo by Colorimeter CL400, measuring the erythema index. The results suggest that the FBA represents an innovative way to exploit the benefits of butyric acid in the cosmetic fields since it cannot reach the bloodstream, is odorless, and has a significative soothing action (decrease the erythema index −15.7% after 30′, and −17.8% after 60′).     

A Mechanistic Overview of the Current Status and Future Challenges of Aluminum Anode and Electrolyte in Aluminum-Air Batteries

Aluminum-air batteries (AABs) are regarded as attractive candidates for usage as an electric vehicle power source due to their high theoretical energy density (8100 Wh kg⁻¹), which is considerably higher than that of lithium-ion batteries. However, AABs have several issues with commercial applications. In this review, we outline the difficulties and most recent developments in AABs technology, including electrolytes and aluminum anodes, as well as their mechanistic understanding. First, the impact of the Al anode and alloying on battery performance is discussed. Then we focus on the impact of electrolytes on battery performances. The possibility of enhancing electrochemical performances by adding inhibitors to electrolytes is also investigated. Additionally, the use of aqueous and non-aqueous electrolytes in AABs is also discussed. Finally, the challenges and potential future research areas for the advancement of AABs are suggested.