Taylor Bubble Study of the Influence of Fluid Dynamics on Yield and Selectivity in Fast Gas-Liquid Reactions

A consecutive competitive gas-liquid reaction is investigated using a Taylor bubble setup regarding the influence of fluid mixing in the bubble wake on yield and selectivity. The concentration fields behind a Taylor bubble are visualized and measured quantitatively with a novel time-resolved absorption imaging technique based on Beer Lamberts law and an integral selectivity is derived. In addition, the calculation of the local selectivity, often used in numerical approaches, is discussed and the existing experimental limits for its derivation are pointed out. Finally, an increase in selectivity of a competitive consecutive reaction for enhanced mixing is experimentally confirmed.     

Mesoporous drug carrier systems for enhanced delivery rate of poorly water-soluble drug: nimodipine

Journal of Porous Materials - Two mesoporous silica materials: MCM-41 and SBA-15 were applied as potential nanocarriers for poorly soluble drug—nimodipine. Drug incorporation was performed...     

Active Site Mapping of Human Cathepsin F with Dipeptide Nitrile Inhibitors

Cleavage of the invariant chain is the key event in the trafficking pathway of major histocompatibility complex class II. Cathepsin S is the major processing enzyme of the invariant chain, but cathepsin F acts in macrophages as its functional synergist which is as potent as cathepsin S in invariant chain cleavage. Dedicated low‐molecular‐weight inhibitors for cathepsin F have not yet been developed. An active site mapping with 52 dipeptide nitriles, reacting as covalent–reversible inhibitors, was performed to draw structure–activity relationships for the non‐primed binding region of human cathepsin F. In a stepwise process, new compounds with optimized fragment combinations were designed and synthesized. These dipeptide nitriles were evaluated on human cysteine cathepsins F, B, L, K and S. Compounds 10 (N‐(4‐phenylbenzoyl)‐leucylglycine nitrile) and 12 (N‐(4‐phenylbenzoyl)leucylmethionine nitrile) were found to be potent inhibitors of human cathepsin F, with K_i values <10 nM . With all dipeptide nitriles from our study, a 3D activity landscape was generated to visualize structure–activity relationships for this series of cathepsin F inhibitors.     

Computer Simulations Then and Now: an Introduction and Historical Reassessment

NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin -     

In situ Characterization of SiO2 Nanoparticle Biointeractions Using BrightSilica

By adding a gold core to silica nanoparticles (BrightSilica), silica‐like nanoparticles are generated that, unlike unmodified silica nanoparticles, provide three types of complementary information to investigate the silica nano‐biointeraction inside eukaryotic cells in situ. Firstly, organic molecules in proximity of and penetrating into the silica shell in live cells are monitored by surface‐enhanced Raman scattering (SERS). The SERS data show interaction of the hybrid silica particles with tyrosine, cysteine and phenylalanine side chains of adsorbed proteins. Composition of the biomolecular corona of BrightSilica nanoparticles differs in fibroblast and macrophage cells. Secondly, quantification of the BrightSilica nanoparticles using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) micromapping indicates a different interaction of silica nanoparticles compared to gold nanoparticles under the same experimental conditions. Thirdly, the metal cores allow the investigation of particle distribution and interaction in the cellular ultrastructure by cryo nanoscale X‐ray tomography (cryo‐XT). In 3D reconstructions the assumption is confirmed that BrightSilica nanoparticles enter cells by an endocytotic mechanism. The high SERS intensities are explained by the beneficial plasmonic properties due to agglomeration of BrightSilica. The results have implications for the development of multi‐modal qualitative and quantitative characterization in comparative nanotoxicology and bionanotechnology.     

Structural and electrical properties of grain boundaries in Ce0.85Gd0.15O1.925 solid electrolyte modified by addition of transition metal ions

In this work we present studies on applicability of transition metal additives as sintering and electrical conductivity aids for cerium gadolinium oxide electrolyte. The nanosized Ce_0.85Gd_0.15O_1.925 powder obtained by coprecipitation method was modified with Cr³⁺, Fe³⁺, Ni²⁺ or Cu²⁺ ions. Using high-intensity high-resolution X-ray powder diffraction data we have determined that Cr, Fe and Ni ions do not incorporate into the cerium gadolinium oxide surface or bulk when sintered at 1300 °C, but react with Gd ions to form Cr_0.9Gd_0.1O, GdFeO₃ and GdNiO₃ phases, while Cu incorporates in the material up to 0.7 mol% with a significant fraction of remaining material showing poorly crystalline CuO phase. The nanosized Ce_0.85Gd_0.15O_1.925 material shows already improved sintering properties than previous reports but full sintering is not achieved below 1300 °C, however Cr, Fe and mainly Cu impregnation allows full sintering at 1300 °C. 0.5 mol% Ni impregnated material sintered at 1500 °C shows enhanced grain boundary conductivity that probably indicates that Ni incorporates into Ce_0.84Gd_0.15O_1.925 above 1300 °C. The global results indicate, however, that optimization of ceria microstructure is at least of equal importance for sinterability and grain boundary conductivity than impregnation of the material with transition metal ions.     

Thermal stability of poly(2-ethylhexyl acrylates) used as plasticizers for medical application

This article discusses thermal analysis of different molecular weight poly(2-ethylhexyl acrylates) synthesized by radical polymerization of 2-ethylhexyl acrylate. The main aim of this work was to investigate the thermal properties and degradation process of synthesized acrylic homopolymers and forming of thermal degradation products during their pyrolysis. As investigated method pyrolysis combined with gas chromatography was used. Poly(2-ethylhexyl acrylates) are used as plasticizers for pressure-sensitive adhesives applied in medical area.     

Sintering of Colloidal Ru/γ-Al2O3 Catalyst in Hydrogen

Colloidal 5.1 wt% Ru/γ-Al₂O₃ catalyst was prepared by a microwave assisted, solvothermal reduction of RuCl₃ in ethylene glycol in the presence of γ-Al₂O₃. The catalyst subjected to heat-treatment in hydrogen up to 700 °C, was characterized by BET, XRD, TEM and H₂ chemisorption. As-prepared catalyst contained Ru nanoparticles with mean size of 1.5 nm and narrow size distribution uniformly distributed over the support. The nanoparticles were stable on the alumina to 500 °C, but treatment at 600–700 °C caused some sintering of Ru due to migration and coalescence of a part of smallest ruthenium nanoparticles. However, even after H₂ treatment at 700 °C, large amount of Ru nanoparticles with sizes of 1–3 nm remained in the catalyst. H₂ chemisorption data revealed decrease of Ru dispersion from 0.28 to 0.19 by hydrogen treatment at 700 °C and were in good correspondence with TEM results. On the contrary, mean crystallite sizes obtained from XRD were strongly overestimated.     

The Synthesis of Vicinal Diacylamines via Bamberger Ring Cleavage of Substituted Imidazoles. 1,2,4-Triacylaminobutanes Bearing Different Acyl Groups

Bamberger ring cleavage acylation of N-p-toluenesulfonyl (tosyl) histamine followed by hydrogenation yields 3,4-diacylaminobutanetosylamine, a triamine containing groups with different chemical reactivities.