Search results for "Cyclic compound"
showing 10 items of 819 documents
Coordination-Induced Spin-State Switching with Nickel Chlorin and Nickel Isobacteriochlorin
2015
We present the first coordination-induced spin-state switching with nickel chlorin and nickel isobacteriochlorin. The spin-state switching was monitored by UV-vis spectroscopy and NMR titration experiments. The association constants (K1 and K2) and thermodynamic parameters (ΔH and ΔS) of the coordination of pyridine were determined. The first X-ray analyses of a paramagnetic nickel chlorin and a nickel isobacteriochlorin provide further information about the structure of the octahedral complexes. Nickel chlorin and even more pronounced nickel isobacteriochlorin exhibit stronger coordination of axial ligands compared to the corresponding nickel porphyrin and thus provide the basis for more e…
Prediction of properties of chiral compounds by molecular topology
1998
Abstract A common assumption in chemistry is that chiral behavior is associated with 3-D geometry. However, chiral information is related to symmetry, which allows the topological handling of chiral atoms by weighted graphs and the calculation of new descriptors that give a weight to the corresponding entry in the main diagonal of the topological matrix. In this study, it is demonstrated that, operating in this way, chiral topological indices are obtained that can differentiate the pharmacological activity between pairs of enantiomers. The 50% inhibitory concentration (IC50) values of the D2 dopamine receptor and the σ receptor for a group of 3-hydroxy phenyl piperidines are specifically pr…
MONENSIN ENHANCES DIGOXIN-INDUCED ARRHYTHMIAS IN GUINEA-PIGS
1993
Effects of pretreatment with monensin (150 ug/kg), atenolol (0.3 mg/kg), atenolol plus monensin, verapamil (0.38 mg/kg), verapamil plus monensin, glibenclamide(0.38 mg/kg) and glibenclamide plus monensin on the dose of digoxin required to induce premature ventricular contractions (PVCS) in anaesthetized guinea-pigs were studied. Monensin reduced while atenolol increased the dose of digoxin required to produce PVCS. Atenolol plus monensin increased the dose of digoxin required to produce PVCS in presence of monensin alone. Verapamil reduces the arrhythmogenic effect of monensin on digoxin. Glibenclamide antagonises the effect of monensin on digoxin induced PVCS. From the present data it coul…
Promoting the activity and selectivity of high surface area Ni–Ce–O mixed oxides by gold deposition for VOC catalytic combustion
2011
Gold supported on nickel cerium oxide catalysts (Ni–Ce–O) have been studied for the total oxidation of propane, as a model for hydrocarbon volatile organic compound emission control. High surface area Ni–Ce–O catalysts were synthesized using a very simple evaporation method, where cerium and nickel salts were evaporated in the presence of a mixture of methanol and oxalic acid. Gold catalysts were prepared following a deposition–precipitation method. A very efficient catalyst for the oxidation of propane, in terms of both activity and selectivity, was obtained. This high activity has been related to the high surface area of the catalyst (and therefore to the presence of more active sites ava…
Phosphonium-Boronate Amino Acid Derivatives as Fluoride Pincers for 18F-Labelling
2015
The synthesis of phosphonium-boronate amino acid derivatives was achieved by quaternization of o-boronatophenylphosphine with iodo-amino acid derivatives. Preliminary radiolabelling studies demonst...
Enantioselective transport of amino acid through supported chiral liquid membranes
1993
Abstract Two chiral alcohols, nopol and (2S)-(−)-methyl-1-butanol, immobilized in the pores of a polyethylene film were used for the anantioselective transport of amino acid hydrochloride. The degree of stereoselectivity of the permeation process varied from 0.39 to 1.52 depending on both the type of the chiral membrane phase and the properties of the amino acid. The evaluation of the membrane ability to separate stereoisomers was performed by the step-by-step analysis by considering the effect of amino acids' hydrophobicity, polarity and degree of chirality. For the purpose of this paper, the chirality measure was introduced. It was demonstrated that the enantioselectivity was affected mai…
ORR Activity and Stability of Co-N/C Catalysts Based on Silicon Carbide Derived Carbon and the Impact of Loading in Acidic Media
2018
This work was supported by the EU through the European Regional Development Fund under projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR ”Nanomaterials - research and applications” (3.2.0304.12-0397) and by the Estonian institutional research grant No. IUT20-13.
Novel method for determination of tritium depth profiles in metallic samples
2019
Tritium accumulation in fusion reactor materials is considered a serious radiological issue, therefore a lot of effort has been concentrated on the development of radiometric techniques. A novel method, based on gradual dissolution, for the determination of the total tritium content and its depth profiles in metallic samples is demonstrated. This method allows for the measurement of tritium in metallic samples after their exposure to a hydrogen and tritium mixture, tritium containing plasma or after irradiation with neutrons resulting in tritium formation. In this method, successive layers of metal are removed using an appropriate etching agent in the controlled regime and the amount of evo…
ortho-(Dimesitylboryl)phenylphosphines: Positive Boryl Effect in the Palladium-Catalyzed Suzuki-Miyaura Coupling of 2-Chloropyridines
2013
The presence of ortho-dimesitylboryl moiety in the catalyst is crucial to enhance the catalytic performance.
Retinal Microcirculation in Type 1 Diabetic Patients With and Without Peripheral Sensory Neuropathy
2014
In patients with diabetes mellitus (DM), early retinal microvascular alterations can be observed even before the clinical diagnosis of diabetic retinopathy. This study aimed to investigate morphological and functional changes in retinal microvascular blood flow in type 1 diabetic patients with and without peripheral neuropathy (PNP) as compared to nondiabetic controls. Retinal microvascular blood flow (RBF) was assessed using scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter, Heidelberg Engineering, Germany) before and after stimulation with flicker light. PNP was assessed using the neuropathy disability score (NDS) and by the evaluation of the vibration perception threshold (V…