Search results for "Kinetics"
showing 10 items of 2224 documents
IMI – Oral biopharmaceutics tools project – Evaluation of bottom-up PBPK prediction success part 4: Prediction accuracy and software comparisons with…
2020
Oral drug absorption is a complex process depending on many factors, including the physicochemical properties of the drug, formulation characteristics and their interplay with gastrointestinal physiology and biology. Physiological-based pharmacokinetic (PBPK) models integrate all available information on gastro-intestinal system with drug and formulation data to predict oral drug absorption. The latter together with in vitro-in vivo extrapolation and other preclinical data on drug disposition can be used to predict plasma concentration-time profiles in silico. Despite recent successes of PBPK in many areas of drug development, an improvement in their utility for evaluating oral absorption i…
Supramolecular Eutecto Gels: Fully Natural Soft Materials
2018
The obtainment of materials featured by high environmental compatibility is one of the main goals of modern research. On this subject, we herein report the first example of supramolecular gel in deep eutectic solvents. In particular, we prepared gels of the L-amino acids isoleucine and tryptophan in choline chloride/phenylacetic acid 1:2. All gel components are readily available and nontoxic. Gels have been fully characterized by standard gelation tests, rheology, X-ray diffraction, morphology and gelation kinetics. Data collected show that gels properties depend on the gelator nature. In particular, gel phases exhibit strong colloidal forces and, this high mechanical resistance, together w…
Endocrine disrupter compounds removal in wastewater using microalgae: Degradation kinetics assessment
2018
[EN] This paper describes a study carried out to determine the removal kinetics of four micropollutants (4-tert-octylphenol (OP), technical-nonylphenol (t-NP), 4-nonylphenol (4-NP) and bisphenol-A (BPA)) usually found in wastewater streams. The kinetic experiments were carried out in batch reactors containing the effluent of an Anaerobic Membrane BioReactor (AnMBR) in the presence of light, oxygen and microalgae. As the degradation process of the studied micropollutants obeyed a pseudo-first-order kinetics, the second-order kinetics for each micropollutant was then calculated. The second order rate constants for the hydroxyl radical (k.(OH)) ranged from 7.0.10(+10) to 6.6.10(+12) L.mol(-1).…
Perovskite CH3NH3PbI3–XClx Solar Cells. Experimental Study of Initial Degradation Kinetics and Fill Factor Spectral Dependence
2021
The main drawback of the methylammonium lead halide perovskite solar cells is their degradation in ambient atmosphere. To investigate ambient-air-induced cell degradation, spec-tral dependencies of open-circuit voltage (VOC), fill factor (FF) and the power conversion effi-ciency (PCE) have been acquired (for the first time reported in literature). Our custom-made measurement system allowed us to perform measurements of the above-mentioned entities in situ directly in vacuum during and after thermal deposition of the elec-trode. We also studied how these parameters in vacuum changed after cell exposure to ambient air for 85 min (50 nm top electrode) and for 180 min (100 nm top Ag electrode).…
Modelling denitrification including the dynamics of denitrifiers and their progressive ability to reduce nitrous oxide: comparison with batch experim…
2005
Nitrous oxide contributes to the global greenhouse effect and affects the chemistry of O 3 in the upper troposphere and lower stratosphere. To define a relevant model for microbial NO 3 - and N 2 O reductions in soil and estimate the parameters involved, we propose a method combining measurements of anaerobic soil slurry and simulations of NO 3 - and N 2 O reductions, including non-enzymatic competition between NO 3 - and N 2 O as electron acceptors and the microbial dynamics of two denitrifier groups that are either able or unable to reduce N 2 O. Three models varying in the description of soil capability to reduce N 2 O through denitrification were assessed. The procedure was applied on a…
Unconventional Fluorescence Quenching in Naphthalimide-Capped CdSe/ZnS Nanoparticles
2013
Core–shell (CS) CdSe/ZnS quantum dots (QD) capped with ligands that possess a mercapto or an amino group and a naphthalimide (NI) as chromophore unit, linked by a short ethylene chain (CS@S–NI and CS@H2N–NI, respectively), have been synthesized and fully characterized by infrared and nuclear magnetic resonance spectroscopies, high-resolution transmission electron microscopy, and voltammetry as well as by steady-state absorption and emission spectroscopies. The organic ligands HS–NI and H2N–NI act as bidentate ligands, thereby causing a drastic decrease in the QD emission. This was particularly evident in the case of CS@S–NI. This behavior has been compared with that of commercially availabl…
Fast redox-triggered shuttling motions in a copper rotaxane based on a phenanthroline–terpyridine conjugate
2014
Fast shuttling motions in solution have been observed by cyclic voltammetry in a Cu(I/II)-based [2] rotaxane. In the reported system, the different coordination preferences of both copper oxidation states are exploited to promote the electrochemically-triggered gliding of the ring from a tetra to a pentacoordinated site and vice versa. The thread of this rotaxane consists of a tridentate 2,2':6',2''-terpyridine chelating unit directly bonded through its 5-position to the 3-position of the bidentate 1,10-phenanthroline unit. This distribution reduces to a minimum the distance between the two coordination sites and lessens the congestion around the tetrahedral environment. These two factors h…
DNA binding, nuclease activity, DNA photocleavage and cytotoxic properties of Cu(II) complexes of N-substituted sulfonamides.
2013
Abstract Ternary copper(II) complexes [Cu(NST)2(phen)] (1) and [Cu(NST)2(NH3)2]·H2O (2) [HNST = N-(4,5-dimethylthiazol-2-yl)naphthalene-1-sulfonamide] were prepared and characterized by physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square planar CuN4 geometry in which the deprotonated sulfonamide, acting as monodentate ligand, binds to the metal ion through the thiazole N atom. Both complexes present intermolecular π–π stacking interactions between phenanthroline rings (compound 1) and between naphthalene rings (compound 2). The interaction of the complexes with CT DNA was studied b…
From the covalent linkage of drugs to novel inhibitors of ribonucleotide reductase: synthesis and biological evaluation of valproic esters of 3'-C-me…
2014
We synthesized a series of serum-stable covalently linked drugs derived from 3'-C-methyladenosine (3'-Me-Ado) and valproic acid (VPA), which are ribonucleotide reductase (RR) and histone deacetylase (HDAC) inhibitors, respectively. While the combination of free VPA and 3'-Me-Ado resulted in a clear synergistic apoptotic effect, the conjugates had lost their HDAC inhibitory effect as well as the corresponding apoptotic activity. Two of the analogs, 2',5'-bis-O-valproyl-3'-C-methyladenosine (A160) and 5'-O-valproyl-3'-C-methyladenosine (A167), showed promising cytotoxic activities against human hematological and solid cancer cell lines. A167 was less potent than A160 but had interesting featu…
Deoxysarpagine Hydroxylase — A Novel Enzyme Closing a Short Side Pathway of Alkaloid Biosynthesis in Rauvolfia
2002
Microsomal preparations from cell suspension cultures of the Indian plant Rauvolfia serpentina catalyze the hydroxylation of deoxysarpagine under formation of sarpagine. The newly discovered enzyme is dependent on NADPH and oxygen. It can be inhibited by typical cytochrome P450 inhibitors such as cytochrome c, ketoconazole, metyrapone, tetcyclacis and carbon monoxide. The CO-effect is reversible with light (450 nm). The data indicate that deoxysarpagine hydroxylase is a novel cytochrome P450-dependent monooxygenase. A pH optimum of 8.0 and a temperature optimum of 35 degrees C were determined. K(m) values were 25 microM for NADPH and 7.4 microM for deoxysarpagine. Deoxysarpagine hydroxylase…