986 research outputs found
Presencia de laminación oblicua a gran escala en las turbiditas senoenses del flysch de los alrededores de la Pobla de Segur (prov. Lérida)
En un corte cerca de la Pobla de Segur (Pirineos meridionales), se encuentran unas capas con laminación cruzada a gran escala, de hasta 30 cm de espesor, en una formación de turbiditas del Cretáceo Superior. Estas capas tienen generalmente forma de cuña o lentejón y se caracterizan por poseer superficies netas de contacto en el techo y yacente. Sólo en pocos casos están cubiertas por un delgado intervalo de limolitas con ripples de corriente.La laminación cruzada tiene un buzamiento de 5 a 30° y está uniformemente inclinada, al igual que los flute-casts, en la misma dirección que la corriente. Estos últimos se encuentran en el yacente de las mencionadas capas o en la base de las turbiditas asociadas.Estas características representan formas geométricas de dunas o barras originadas por un régimen de corriente menos intenso
Catalytic Promiscuity of Galactose Oxidase: A Mild Synthesis of Nitriles from Alcohols, Air, and Ammonia
Kinetic Resolution of Racemic Primary Amines Using <i>Geobacillus stearothermophilus</i> Amine Dehydrogenase Variant
Kinetic Resolution of Racemic Primary Amines Using <i>Geobacillus stearothermophilus</i> Amine Dehydrogenase Variant
A NADH‐dependent engineered amine dehydrogenase from Geobacillus stearothermophilus (LE‐AmDH‐v1) was applied together with a NADH‐oxidase from Streptococcus mutans (NOx) for the kinetic resolution of pharmaceutically relevant racemic α‐chiral primary amines. The reaction conditions (e. g., pH, temperature, type of buffer) were optimised to yield S‐configured amines with up to >99 % ee
Crystallization-based downstream processing of ω-transaminase- and amine dehydrogenase-catalyzed reactions
Biocatalytic synthesis is a powerful and frequently chosen method for the production of chiral amines. Unfortunately, these biocatalytic reactions often result in complex mixtures, bearing many components aside from the main product amine such as residual co-substrates, co-products, cofactors and buffer salts. This issue typically requires an additional effort during downstream processing towards the isolation of the desired chiral amine. For instance, transaminase- and amine dehydrogenase-catalyzed reactions, which often use high surpluses of amine or ammonia co-substrates, face complications in removing the residual amine donor or unreacted substrate and salts from the isolated amine products, thus complicating and increasing the costs of the process of product isolation and purification. This study explores the selective removal of chiral amines from model amine transaminase and amine dehydrogenase-catalyzed reactions via a salt-based specific crystallization step. The product amine is precipitated directly in one step from the reaction mixture as a product ammonium salt, which can easily be filtered from the reaction mixture, while the other reactants remain unchanged in solution for potential re-use.</p
Continuous Flow Biocatalytic Reductive Amination by Co-Entrapping Dehydrogenases with Agarose Gel in a 3D-Printed Mould Reactor
Herein, we show how the merge of biocatalysis with flow chemistry aided by 3D-printing technologies can facilitate organic synthesis. This concept was exemplified for the reductive amination of benzaldehyde catalysed by co-immobilised amine dehydrogenase and formate dehydrogenase in a continuous flow micro-reactor. For this purpose, we investigated enzyme co-immobilisation by covalent binding, or ion-affinity binding, or entrapment. Entrapment in an agarose hydrogel turned out to be the most promising solution for this biocatalytic reaction. Therefore, we developed a scalable and customisable approach whereby an agarose hydrogel containing the co-entrapped dehydrogenases was cast in a 3D-printed mould. The reactor was applied to the reductive amination of benzaldehyde in continuous flow over 120 h and afforded 47 % analytical yield and a space-time yield of 7.4 g L day−1 using 0.03 mol% biocatalysts loading. This work also exemplifies how rapid prototyping of enzymatic reactions in flow can be achieved through 3D-printing technology
Precision Measurement of the 29Si, 33S, and 36Cl Binding Energies
The binding energies of 29Si, 33S, and 36Cl have been measured with a
relative uncertainty using a flat-crystal spectrometer.
The unique features of these measurements are 1) nearly perfect crystals whose
lattice spacing is known in meters, 2) a highly precise angle scale that is
derived from first principles, and 3) a gamma-ray measurement facility that is
coupled to a high flux reactor with near-core source capability. The binding
energy is obtained by measuring all gamma-rays in a cascade scheme connecting
the capture and ground states. The measurements require the extension of
precision flat-crystal diffraction techniques to the 5 to 6 MeV energy region,
a significant precision measurement challenge. The binding energies determined
from these gamma-ray measurements are consistent with recent highly accurate
atomic mass measurements within a relative uncertainty of .
The gamma-ray measurement uncertainties are the dominant contributors to the
uncertainty of this consistency test. The measured gamma-ray energies are in
agreement with earlier precision gamma-ray measurements.Comment: 13 pages, 4 figure
Multi-Channel Lanthanide Nanocomposites for Customized Synergistic Treatment of Orthotopic Multi-Tumor Cases
<p>Simultaneous photothermal ablation of multiple tumors is limited by unpredictable photo-induced apoptosis, caused by individual intratumoral differences. Here, a multi-channel lanthanide nanocomposite was used to achieve tailored synergistic treatment of multiple subcutaneous orthotopic tumors under non-uniform whole-body infrared irradiation prescription. The nanocomposite reduces intratumoral glutathione by simultaneously activating the fluorescence and photothermal channels. The fluorescence provides individual information on different tumors, allowing customized prescriptions to be made. This enables optimal induction of hyperthermia and dosage of chemo drugs, to ensure treatment efficacy, while avoiding overtherapy. With an accessional therapeutic laser system, customized synergistic treatment of subcutaneous orthotopic cancer cases with multiple tumors is possible with both high efficacy and minimized side effects.</p>
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