Search results for "acetate"
showing 10 items of 756 documents
Pretreatment with gonadotropin-releasing hormone (GnRH) antagonists to prevent the flare-up effect of long-acting GnRH agonists: results of a pilot s…
2007
This study evaluated in vivo whether the flare-up effect of GnRH agonists can be suppressed through pretreatment with a GnRH antagonist. The classic flare-up effect caused by 3.8 mg goserelin acetate could not be suppressed through pretreatment using a single dosage of 3.24 mg cetrorelix acetate.
Intermittent operation of UASB reactors treating wastewater polluted with organic solvents: process performance and microbial community evaluation
2019
The effect of intermittent feeding on the treatment of wastewater polluted with ethanol, ethyl acetate and 1-ethoxy-2-propanol in anaerobic upflow sludge blanket reactors was investigated. Three laboratory-scale reactors, one periodically supplemented with chitosan, were operated in an intermittent pattern (16 hours per day; 5 days per week) during 5 months. Removal efficiencies higher than 94% were obtained at organic loading rates up to 50 kg COD m−3 d−1. The addition of chitosan positively affected the specific methanogenic activity of the granular sludge. Although partial deterioration of the granules was observed, it was not correlated with variations in the production of extracellular…
Catalytic Enantioselective Aza-Reformatsky Reaction with Cyclic Imines
2016
A catalytic highly enantioselective aza-Reformatsky reaction with cyclic aldimines and ketimines for the synthesis of chiral b-amino esters with good yields and excellent enantioselectivities is reported.Areadily available diaryl prolinol is used as a chiral ligand, ZnMe2 as a zinc source and ethyl iodoacetate as reagent in the presence of air atmosphere. The reaction with cyclic ketimines generates a quaternary stereocenter with excellent levels of enantioselectivity. Furthermore, five-membered N-sulfonyl ketimines were used as electrophiles with good enantiomeric excesses, under the optimized reaction conditions. Moreover, several chemical transformations were performed with the chiral b-…
Functionalization of CnH2n+2Alkanes: Supercritical Carbon Dioxide Enhances the Reactivity towards Primary Carbon-Hydrogen Bonds
2015
The functionalization of the primary sites of alkanes is one of the more challenging areas in catalysis. In this context, a novel effect has been discovered that is responsible for an enhancement in the reactivity of the primary C-H bonds of alkanes in a catalytic system. The copper complex Cu(NCMe) (=hydrotris{[3,5-bis(trifluoromethyl)-4-bromo]-pyrazol-1-yl}borate) catalyzes the functionalization of CnH2n+2 with ethyl diazoacetate upon inserting the CHCO2Et unit into C-H bonds. In addition, the selectivity of the reaction toward the primary sites significantly increased relative to that obtained in neat alkane upon using supercritical carbon dioxide as the reaction medium. This was attribu…
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…
Unsaturated syn- and anti-1,2-Amino Alcohols by Cyclization of Allylic Bis-trichloroacetimidates. Stereoselectivity Dependence on Substrate Configura…
2014
Disubstituted allylic bis-imidates undergo Lewis acid catalyzed or spontaneous cyclization to oxazolines, which are precursors of unsaturated amino alcohols. Stereoselectivity of the cyclization is mainly determined by the substrate configuration. Highly selective cis-oxazoline formation is achieved starting from anti-E-bis-imidates while trans-oxazoline predominantly forms from anti-Z-bis-imidates. On the basis of DFT calculations, the stereoselectivity trends can be explained by the formation of the energetically most stable carbenium ion conformation, followed by the cyclization via most favorable bond rotations.
A Simple Procedure for Oxidation of Alcohols using [Bis(acetoxy)iodo]benzene and a Catalytic Amount of Bromide Ions in Ethyl Acetate
2015
Primary and secondary benzylic alcohols and secondary aliphatic alcohols were oxidized to the corresponding aldehydes and ketones by using [bis(acetoxy)iodo]benzene (BAIB) and a catalytic amount of bromide ions, from tetrabutylammonium bromide or KBr, in ethyl acetate. The catalytic role of the bromide ions was also highlighted in the oxidation of primary aliphatic alcohols and secondary allylic alcohols carried out in the presence of 1 mol% TEMPO.
The Effect of Electronic Properties of Anodized and Hard Anodized Ti and Ti6Al4V on Their Reactivity in Simulated Body Fluid
2022
The electronic properties of barrier and porous layers on Ti and Ti6Al4V were studied. Barrier anodic oxides grown to 40 V on Ti and on Ti6Al4V are both n-type semiconductors with a band gap of 3.3 eV and 3.4 eV respectively, in agreement with the formation of amorphous TiO2. Anodizing to 200 V at 20 mA cm−2 in calcium acetate and β-glycerol phosphate disodium pentahydrate leads to the formation of Ca and P containing porous films with a photoelectrochemical behaviour dependent on the metallic substrate. A band gap of 3.2 eV and the flat band potential of −0.5 V vs Ag/AgCl were measured for the porous oxide on Ti, while optical transitions at 2.15 eV and a significantly more positive flat b…
Activation of classical protein kinase C decreases transport via systems y+and y+L
2007
Activation of protein kinase C (PKC) downregulates the human cationic amino acid transporters hCAT-1 (SLC7A1) and hCAT-3 (SLC7A3) (Rotmann A, Strand D, Martiné U, Closs EI. J Biol Chem 279: 54185–54192, 2004; Rotmann A, Vekony N, Gassner D, Niegisch G, Strand D, Martine U, Closs EI. Biochem J 395: 117–123, 2006). However, others found that PKC increased arginine transport in various mammalian cell types, suggesting that the expression of different arginine transporters might be responsible for the opposite PKC effects. We thus investigated the consequence of PKC activation by phorbol-12-myristate-13-acetate (PMA) in various human cell lines expressing leucine-insensitive system y+[hCAT-1, h…
Keyhole limpet haemocyanin: negative staining in the presence of trehalose
1995
Abstract Samples of unpurified and purified haemocyanin from the giant keyhole limpet Megathura crenulata have been studied by transmission electron microscopy (TEM) using mixtures of trehalose with the negative stains, uranyl acetate and ammonium molybdate. Trehalose is a known protein preservative during air and freeze drying, UV irradiation and high temperatures, and therefore offers the possibility of protecting proteins during the drying of negatively-stained specimens and their subsequent electron microscopical study. Evidence is presented that trehalose possesses satisfactory stability within the electron beam during conventional room temperature, negative-staining studies. The combi…