Preparation and characterization of octadecyl acrylate monoliths for capillary electrochromatography by photochemical,thermal, and chemical initiation†

Monolithic stationary phases based on octadecyl acrylate for CEC using different initiating systems (UV irradiation, thermal, and chemical initiation) in the presence of lauroyl peroxide as initiator were synthesized. For each initiation mode, the influence of the porogenic solvent composition on both the morphological and electrochromatographic properties of the resulting monoliths was investigated. Under optimal conditions, excellent efficiencies for the photochemically and chemically polymerized monoliths (minimum plate heights of 6.9–10.7 and 6.5–12.6 μm, respectively) were achieved. Thermally initiated columns gave lower efficiency values, permeabilities, and longer analysis times compared to these initiating systems. The produced monolithic stationary phases were evaluated in terms of reproducibility and gave RSD values below 9.2, 10.6, and 9.8% for UV, thermally, and chemically initiated columns, respectively.     

Galvanostatically Deposited PtNi Thin-Films as Electrocatalysts for the Hydrogen Evolution Reaction

The synthesis of hybrid platinum materials is fundamental to enable alkaline water electrolysis for cost-effective H₂ generation. In this work, we have used a galvanostatic method to co-deposit PtNi films onto polycrystalline gold. The surface concentrations of Ni (Γ_Ni) and Pt (Γ_Pt) were calculated from electrochemical measurements; the Γ_Pt/Γ_Ni ratio and electrocatalytic activity of these materials towards hydrogen evolution reaction (HER) in 1 M KOH show a strong dependence on the current density pulse applied during the electrodeposition. Analysis of the Tafel parameters hints that, on these deposits, HER proceeds through a Volmer-Heyrovsky mechanism. The galvanostatically deposited PtNi layers present a high current output per Pt gram, 3199 A g_Pt⁻¹, which is significantly larger compared to other PtNi-based materials obtained by more extended and more complex synthesis methods.     

Electro-flow focusing: the high-conductivity low-viscosity limit

Electro-flow focusing, a technique combining the features of electrospray (ES) and flow focusing (FF), provides a reliable tool to reach parametrical microjetting ranges not attainable by ES or FF alone under specific operational regimes (liquid properties and flow rate). In this Letter, we provide not only a closed theoretical model predicting the diameter of a high electrical conductivity electro-flow focused liquid microjet, but also its convective or absolute instability, linked to the jetting-to-dripping transition and the minimum liquid flow rate that can be ejected in steady jetting regime, in which the smallest droplets are issued. Good agreement is found with experimental values.     

Real‐Time In Vivo Detection of Cellular Senescence through the Controlled Release of the NIR Fluorescent Dye Nile Blue

In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR‐FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide ( S3 ). NB emission at 672 nm is highly quenched inside S3 , yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of β‐galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK‐Mel‐103 and breast cancer 4T1 cells and in vivo in palbociclib‐treated BALB/cByJ mice bearing breast cancer tumor.     

Characteristic ratio of the mean-square end-to-end distance of poly(vinylidene fluoride) with microstructural defects

The segment length distribution of isoregic head-to-head and tail-to-tail sequences in poly-(vinylidene fluoride) (PVF₂)

1 System. name: poly(1,1-difluoroethylene).

chains is calculated from ¹⁹F NMR literature data. It is found that the average length of inverse segments is very close to one unit; therefore almost all head-to-head defects are immediately repaired by an adjacent tail-to-tail addition. The role of microstructure on the characteristic ratio of the end-to-end distance is then investigated. Results obtained by two different methods indicate that, in agreement with previous Monte Carlo calculations, defects play a minor role for the conformational characteristics of PVF₂. However, a slight contraction of about 4% is expected for very defective chains.     

Duality Functors for Triple Vector Bundles

We calculate the group of dualization operations for triple vector bundles, showing that it has order 96 and not 72 as given in Mackenzie’s original treatment. The group is a nonsplit extension of S ₄ by the Klein group. Dualization operations are interpreted as functors on appropriate categories and are said to be equal if they are naturally isomorphic. The method set out here will be applied in a subsequent paper to the case of n-fold vector bundles.