Search results for "540"

The maximum carbonyl ratio (MCR) as a new index for the structural classification of secondary organic aerosol components

2021

RATIONALE Organic aerosols (OA) account for a large fraction of atmospheric fine particulate matter and thus are affecting climate and public health. Elucidation of the chemical composition of OA is the key for addressing the role of ambient fine particles at the atmosphere-biosphere interface and mass spectrometry is the main method to achieve this goal. METHODS High-resolution mass spectrometry (HRMS) is on its way to becoming one of the most prominent analytical techniques, also for the analysis of atmospheric aerosols. The combination of high mass resolution and accurate mass determination allows the elemental compositions of numerous compounds to be easily elucidated. Here a new parame…

pH Feedback Lifecycles Programmed by Enzymatic Logic Gates Using Common Foods as Fuels

2021

Abstract Artificial temporal signaling systems, which mimic living out‐of‐equilibrium conditions, have made large progress. However, systems programmed by enzymatic reaction networks in multicomponent and unknown environments, and using biocompatible components remain a challenge. Herein, we demonstrate an approach to program temporal pH signals by enzymatic logic gates. They are realized by an enzymatic disaccharide‐to‐monosaccharide‐to‐sugar acid reaction cascade catalyzed by two metabolic chains: invertase‐glucose oxidase and β‐galactosidase‐glucose oxidase, respectively. Lifetimes of the transient pH signal can be programmed from less than 15 min to more than 1 day. We study enzymatic k…

Improved SiRNA Loading of Cationic Nanohydrogel Particles by Variation of Crosslinking Density

2019

Acid‐Cleavable Poly(ethylene glycol) Hydrogels Displaying Protein Release at pH 5

2020

Abstract PEG is the gold standard polymer for pharmaceutical applications, however it lacks degradability. Degradation under physiologically relevant pH as present in endolysosomes, cancerous and inflammatory tissues is crucial for many areas. The authors present anionic ring‐opening copolymerization of ethylene oxide with 3,4‐epoxy‐1‐butene (EPB) and subsequent modification to introduce acid‐degradable vinyl ether groups as well as methacrylate (MA) units, enabling radical cross‐linking. Copolymers with different molar ratios of EPB, molecular weights (M n) up to 10 000 g mol−1 and narrow dispersities (Đ<1.05) were prepared. Both the P(EG‐co‐isoEPB)MA copolymer and the hydrogels showed pH‐…

Synthesis of (+) and (‐)‐Streptomyces coelicolor Butanolide 5 (SCB‐5)

2021

Tristriazolotriazines with Azobenzene Arms ‐ Acidochromic Dyes and Discotic Liquid Crystals

2019

Crystal structure of 12-benzylsulfanyl-2,9-dibromo-6H-dibenzo[b,g][1,8]naphthyridin-11-one

2015

The hetero-tetra-cene skeleton of the title mol-ecule, C23H14Br2N2OS, is defined by linear annulation of four six-membered rings, including two N heteroatoms. This moiety is nearly planar (r.m.s. deviation = 0.055 Å), with a slight twist of 4.1 (2)° between the two halves of the aromatic system. The dihedral angle between the least-squares plane of the skeleton and the benzyl group is 24.5 (3)°; the C-S-C angle involving the benzyl-sulfanyl group is 99.2 (4)°. In the crystal, mol-ecules are π-stacked in an anti-parallel fashion along [110], with a distance between the aromatic planes of 3.47 (2) Å. Inter-molecular N-H⋯O hydrogen bonds form chains extending parallel to [001] and bridge the a…

Development of a Method for Anodic Degradation of Lignin for the Analysis of Paleo‐Vegetation Proxies in Speleothems

2022

Synthesis, Thermal, and Optical Properties of Tris(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)‐1,3,5‐triazines, New Star‐Shaped Fluorescent Discotic Liquid Crystals

2019

Abstract The synthesis of tris(aryloxadiazolyl)triazines (TOTs), C 3‐symmetrical star‐shaped mesogenes with a 1,3,5‐triazine center, 5‐phenyl‐1,3,4‐oxadiazole arms, and various peripheral alkoxy side chains is reported. Threefold Huisgen reaction on a central triazine tricarboxylic acid and suitable aryltetrazoles yields the title compounds. Selected analogues with a benzene center are included in this study and allow for an evaluation of the impact of the central unit on the physical properties. Thermal (differential scanning calorimetry, DSC; polarization optical microscopy, POM), optical (UV/Vis, fluorescence), electric (time of flight, TOF), and structural (single crystal; wide‐angle X‐…

Exploration of the Activation Mechanism of the Epigenetic Regulator MLL3: A QM/MM Study

2021

The mixed lineage leukemia 3 or MLL3 is the enzyme in charge of the writing of an epigenetic mark through the methylation of lysine 4 from the N-terminal domain of histone 3 and its deregulation has been related to several cancer lines. An interesting feature of this enzyme comes from its regulation mechanism, which involves its binding to an activating dimer before it can be catalytically functional. Once the trimer is formed, the reaction mechanism proceeds through the deprotonation of the lysine followed by the methyl-transfer reaction. Here we present a detailed exploration of the activation mechanism through a QM/MM approach focusing on both steps of the reaction, aiming to provide new…