Search results for "Derivative"
showing 10 items of 1074 documents
Derivatization of ephedrine with o-phthaldialdehyde for liquid chromatography after treatment with sodium hypochlorite.
2000
The usefulness of the reaction with NaClO followed by derivatization with o-phthaldialdehyde (OPA) and N-acetyl-L-cysteine (NAC) has been investigated for the chromatographic analysis of ephedrine. The influence of parameters affecting the two-stage reaction has been evaluated, including concentration of NaClO, time of reaction, temperature and pH. On the basis of these studies, conditions for the pre-column and (automated) post-column determination of ephedrine are presented. The described conditions have been applied to the measurement of ephedrine in the concentration intervals 0.2-20.0 microg/ml and 2.0-50.0 microg/ml for the pre-column and post-column methods, respectively. The possibi…
A cocrystal of two Mo(VI) complexes bearing different diastereomers of the 2,4-di-tert-butyl-6-{[(1-oxido-1-phenylpropan-2-yl)(methyl)amino]methyl}ph…
2013
The title cocrystal contains two chiral conformational diastereomers,viz.(1S,2R,RN)- and (1S,2R,SN)-, of [2,4-di-tert-butyl-6-{[(1-oxido-1-phenylpropan-2-yl)(methyl)amino]methyl}phenolato](methanol)-cis-dioxidomolybdenum(VI), [Mo(C25H35NO2)O2(CH3OH)], representing the first example of a structurally characterized molybdenum complex with enantiomerically pure ephedrine derivative ligands. The MoVIcations exhibit differently distorted octahedral coordination environments, with two oxide ligands positionedcisto each other. The remainder of the coordination comprises phenoxide, alkoxide and methanol O atoms, with an amine N atom completing the octahedron. The distinct complexes are linked by st…
Existence and uniqueness of solution to several kinds of differential equations using the coincidence theory
2015
The purpose of this article is to study the existence of a coincidence point for two mappings defined on a nonempty set and taking values on a Banach space using the fixed point theory for nonexpansive mappings. Moreover, this type of results will be applied to obtain the existence of solutions for some classes of ordinary differential equations. Ministerio de Economía y Competitividad Junta de Andalucía
A preliminary study on the distribution of morphine and its glucuronides in the subcompartments of blood.
1998
[Abstract ] The distribution of morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) in whole blood, plasma, and packed erythrocytes was studied. Parameters investigated were the hematocrit values (10, 42, 44, and 71%) and the water content of the samples. The blood-to-plasma ratio of morphine concentrations was unaffected by variations in hematocrit and water content, whereas the corresponding ratios for M3G and M6G were strongly influenced. Ratios were 0.53 to 0.65 and 0.52 to 0.62 in specimens with average hematocrit values (42 and 44%, respectively), and the ratios were 0.81 or 0.89 (hematocrit 10%) and 0.27 or 0.28 (hemalocrit 71%) in blood samples with different he…
Properties and Structural Studies of Multi-Wall Carbon Nanotubes-Phosphate Ester Hybrids
2013
Long chain phosphate esters bearing at least one or two aryl groups have been synthesized and used for the preparation of stable multi-walled carbon nanotube (MWCNT) hybrids. The non-covalent interaction ester/MWCNT has been investigated by several techniques (SEM, UV-vis, 31P-NMR, RAMAN). The used phosphate ester derivatives demonstrated the ability to produce an excellent dispersion of MWCNT in CHCl3. The obtained dispersions showed a great stability from one to at least three weeks in the range of concentration considered. Thermal analysis showed an increase in the decomposition temperature for the hybrids with respect to pristine MWCNT.
“Functional Poly(ethylene glycol)”: PEG-Based Random Copolymers with 1,2-Diol Side Chains and Terminal Amino Functionality
2010
A series of poly(ethylene glycol-co-isopropylidene glyceryl glycidyl ether) (P(EO-co-IGG)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units was synthesized. After acidic hydrolysis a new type of "functional PEGs", namely poly(ethylene glycol-co-glyceryl glycerol) (P(EO-co-GG)) was obtained. Using an initiator that releases a terminal amino moiety after deprotection, functional end groups with orthogonal reactivity to the in-chain groups were obtained. All polymers showed narrow molecular weight distributions (1.07-1.19), and control of the molecular weights was achieved in the range 5000-30 000 g/mol. Random incorporation of both comonomer…
Stochastic response determination of nonlinear oscillators with fractional derivatives elements via the Wiener path integral
2014
A novel approximate analytical technique for determining the non-stationary response probability density function (PDF) of randomly excited linear and nonlinear oscillators endowed with fractional derivatives elements is developed. Specifically, the concept of the Wiener path integral in conjunction with a variational formulation is utilized to derive an approximate closed form solution for the system response non-stationary PDF. Notably, the determination of the non-stationary response PDF is accomplished without the need to advance the solution in short time steps as it is required by the existing alternative numerical path integral solution schemes which rely on a discrete version of the…
Multiphonon couplings in the sub-barrier fusion of 36S+140Ce
2006
Fusion cross sections have been measured for the system 36S + 140Ce in the energy range encompassing the Coulomb barrier. A representation of the fusion barrier distribution has been obtained from the second energy derivative of the excitation function. The data are well described by coupled‐channels calculations including two‐phonon states of quadrupole and octupole character in the target (140Ce) and one octupole phonon in the projectile. The importance of 140Ce low‐lying inelastic excitations has been pointed out.
The influence study of the number of substituted heteroaryls at the non-K region of pyrene structure on the photophysical properties based on the exa…
2022
The study of the photophysical properties (thermal - thermogravimetric analysis and optical - absorption, emission in the solution and in powder, quantum efficiency of emission and efficient fluorescence lifetime in the solution) with the focus on the influence of the number of substituted 1-decyl-1H-1,2,3-triazole groups at the non-K region of pyrene structure. To the best of our knowledge, the investigation of the impact of the number of heteroaryl groups at the non-K region of pyrene is reported for the first time. The obtained results for monosubstituted derivative (1) were compared to di- (2, 3) and tetra- (4) analogues previously reported by us in the literature. In addition, theoreti…
Thresholding projection estimators in functional linear models
2008
We consider the problem of estimating the regression function in functional linear regression models by proposing a new type of projection estimators which combine dimension reduction and thresholding. The introduction of a threshold rule allows to get consistency under broad assumptions as well as minimax rates of convergence under additional regularity hypotheses. We also consider the particular case of Sobolev spaces generated by the trigonometric basis which permits to get easily mean squared error of prediction as well as estimators of the derivatives of the regression function. We prove these estimators are minimax and rates of convergence are given for some particular cases.