Search results for "Activation"

Favoring alkane primary carbon-hydrogen bond functionalization in supercritical carbon dioxide as reaction medium

2019

The selectivity of a catalytic alkane functionalization process can be modified just changing the reaction medium from neat alkane to supercritical carbon dioxide (scCO2). A silica supported copper complex bearing an Nheterocyclic carbene ligand promotes the functionalization of carbon-hydrogen bonds of alkanes by transferring the CHCO2Et group from N2=CHCO2Et (ethyl diazoacetate, EDA). In neat hexane only 3% of the primary C-H bonds (ethyl heptanoate being the product) are functionalized in that manner, whereas the same reaction carried out in scCO2 provides a 30% yield in this linear ester. Such effect seems to be induced by an electronic density flux from the NHC ligand to the surroundin…

C-H Activation through Semiconductor Photocatalyzed Sulfoxidation of Alkanes

2008

Visible Light Induced Sulfoxidation of Alkanes in the Presence of Titania

2012

Activation of c-Jun N-terminal kinase 1 by UV irradiation is inhibited by wortmannin without affecting c-iun expression.

1999

Activation of c-Jun N-terminal kinases (JNKs)/stress-activated protein kinases is an early response of cells upon exposure to DNA-damaging agents. JNK-mediated phosphorylation of c-Jun is currently understood to stimulate the transactivating potency of AP-1 (e.g., c-Jun/c-Fos; c-Jun/ATF-2), thereby increasing the expression of AP-1 target genes. Here we show that stimulation of JNK1 activity is not a general early response of cells exposed to genotoxic agents. Treatment of NIH 3T3 cells with UV light (UV-C) as well as with methyl methanesulfonate (MMS) caused activation of JNK1 and an increase in c-Jun protein and AP-1 binding activity, whereas antineoplastic drugs such as mafosfamide, mito…

A Combination of Visible-Light Organophotoredox Catalysis and Asymmetric Organocatalysis for the Enantioselective Mannich Reaction of Dihydroquinoxal…

2019

[EN] An enantioselective photooxidative Mannich reaction of dihydroquinoxalinones with ketones by the merger of organophotoredox and asymmetric organocatalysis is described. This protocol features very mild reaction conditions using simple and cheap catalysts (Eosin Y and (S)-Proline) for the synthesis of chiral quinoxaline derivatives with good to high yields (up to 94%) and excellent enantioselectivities (up to 99% ee).

Interruption of CD28-mediated costimulation during allergen challenge protects mice from allergic airway disease

2012

Background Allergic asthma is a T H 2-promoted hyperreactivity with an immediate, IgE, and mast cell–dependent response followed by eosinophil-dominated inflammation and airway obstruction. Objective Because costimulation by CD28 is essential for T H 2 but not T H 1 responses, we investigated the effect of selective interference with this pathway in mice using the models of ovalbumin and house dust mite–induced airway inflammation. Methods To study the role of CD28 in the effector phase of allergic airway inflammation, we developed an inducibly CD28-deleting mouse strain or alternatively used a CD28 ligand-binding site–specific mouse anti-mouse mAb blocking CD28 engagement. Results We show …

Regulation of IgE production and airway reactivity by CD4(-)CD8(-) regulatory T cells

2015

The mechanisms of tolerance induction occurring in the course of allergen-specific immunotherapy have not been elucidated in full detail. Our study aimed to characterize high zone tolerance in mouse models of type I allergy and of allergic airway inflammation induced by subcutaneous sensitization of mice with high doses of the model allergen ovalbumin (OVA) without the use of adjuvant. Mice were immunized by subcutaneous injection of high doses (HD) of OVA or, for comparison, low doses (LD) of OVA in saline. HD-mice showed lower specific IgE, but augmented IgG in sera than LD-mice. Pre-treatment of mice with HD-OVA antigen-specifically inhibited IgE production subsequently induced by LD-OVA…

Technical advance: Soluble OX40 molecule mimics regulatory T cell modulatory activity on FCεRI-dependent mast cell degranulation

2011

ABSTRACT Tregs play a central role in modulating FcɛRI-dependent MC effector functions in the course of the allergic response. Cellular interaction depends on the constitutive expression of OX40 on Tregs and the OX40L counterpart on MCs. Study of OX40L signaling on MCs is hampered by the need of a highly purified molecule, which triggers OX40L specifically. We now report that sOX40 mimics the physiological activity of Treg interaction by binding to activated MCs. When treated with sOX40, activated MCs showed decreased degranulation and Ca++ influx, whereas PLC-γ2 phosphorylation remained unaffected. Once injected into experimental animals, sOX40 not only located within the endothelium but a…

The feasibility of pulsed light processing in the meat industry

2019

Abstract Today, the increasing demand for minimally processed foods that are nutritious, sensorially acceptable, and free from microbial, chemical and physical hazards, challenges research and development to establish alternative methods to reduce the level of bacterial contamination. As one of the newly developing non-thermal methods, pulsed light is a technology for the fast, mild, and residue-free surface decontamination of meat and meat contact materials in the meat processing environment. This review provides specific information on pulsed light technology and the feasibility of its application for unpackaged and packaged meat and meat products as well as meat contact materials. The ad…

Thermostimulated processes in statically and dynamically disordered luminescent solids

1993

Abstract Trap spectra depending on the concentration of defects in crystalline KBr-T1, LiF-Mg, Ti, A1 2 O 3 and glassy Na 2 O·SiO 2 are investigated. The nature of inhomogeneous broadening and continuous distribution of traps over activation energies at sufficiently high defect concentrations is considered. Impurity hopping controlled recombination of electronic excitations is observed. The presence of enlarged values of process activation energies and frequency factors is discussed in terms of the concept of dynamic disorder, taking into account the fluctuational changes in both the perfectpart and the structure of defects in the solid at high temperatures.