Quantification of risperidone and 9-hydroxyrisperidone in plasma and saliva from adult and pediatric patients by liquid chromatography-mass spectrometry

A robust and validated LC-MS-MS quantitative method, using column switching and mutiple reaction monitoring was developed for the analysis of risperidone (RIS) and 9-hydroxyrisperidone in human plasma and saliva. The analytical range was 1-100 ng/ml. The method used 25 microl of sample precipitated with 75 microl of acetonitrile containing internal standard (R068808). Analyses were conducted on a PE Sciex API-III + triple quadrupole mass spectrometer fitted with a Turbo IonSpray source. The method was validated for human plasma using EDTA as the anticoagulant and cross-validated to heparinized human plasma and saliva. The recoveries of risperidone and 9-hydroxyrisperidone were 90-93 and 89-93%, respectively. The validated method was applied to clinical samples to study risperidone and 9-hydroxyrisperidone concentrations in plasma and saliva. Risperidone and 9-hydroxyrisperidone appear in the saliva of patients treated with risperidone. Their detection/quantification in saliva provides evidence for recent adherence with therapy.     

Effects of isolated impurities on atom scattering from crystalline surfaces: Exact quantum-mechanical calculations

A recent method for time-dependent wavepacket scattering calculations is applied to He scattering from a Cu surface with isolated Ar impurities. Several effects are found: (i) broad tails superimposed on each diffraction spike; (ii) shallow impurity rainbow maxima; (iii) impurity—surface interference peaks. A sudden approximation is applied to the interpretation of the newly found features.     

Femtosecond spectroscopy of the (2)1Σ u + double minimum state of Na2: time domain and frequency spectroscopy

Femtosecond time resolved pump-probe experiments studying wave packet dynamics in the (2)¹Σ _u ⁺ double minimum state of Na₂ are reported. The experiments were performed in a molecular beam with ion Time of Flight (TOF) detection. By Fast Fourier Transformation (FFT) of the observed time domain data the energy spacings of the coherently coupled vibrational levels in the (2)¹Σ _u ⁺ potential are obtained with an accuracy of 0.02 cm^?1, although an ultrafast laser source with its inherent spectral width was used in the experiment. The wavelengths of the pump and probe laser pulses are chosen such that in this two color experiment we can control ionisation versus ionisation induced fragmentation. In order to study the influence of the potential barrier on a vibrational wave packet motion we performed simulations based on time dependent quantum calculations.     

Correlation betweenJ c and screw dislocation density in sputtered YBa2Cu3O7-δ films

Electric transport properties of sputtered YBa₂Cu₃O_7– films were studied as a function of screw dislocation density, ranging from 5·10⁷ cm^–2 to 1.3·10⁹ cm^–2 as determined at the film surface. A correlation was found between the number of screw dislocations and the critical current density (J _c ). Films with higher screw dislocation densities have higher critical current densities and a slower drop ofJ _c as a function of applied magnetic fieldH.     

Construction of a nonlocal potential from the scattering amplitude in the born approximation

Within a framework of the Born approximation simplified by certain assumptions, a procedure is given which explicitly constructs a nonlocal potential that provides a fit to elastic scattering data. The data are assumed to consist of the scattering amplitude as a function of the momentum transfer over a finite range of energies. The constructed potential is unique only when the kernel of the nonlocal interaction is energy independent, or when its explicit energy dependence is known from information other than scattering data.     

Synthese,Strukturen und X‐/Q‐Band‐EPR‐Untersuchungen von N,N‐Diethyl‐N′‐3,5‐di(trifluormethyl)benzoylthioureato‐Komplexen des CuII,NiII und PdII sowie EPR‐spektroskopische Charakterisierung eines CuII‐CuII‐Dimers

The synthesis and the structures of (i) the ligand N,N‐Diethyl‐N′‐3,5‐di(trifluoromethyl)benzoylthiourea HEt₂dtfmbtu and (ii) the Ni^II and Pd^II complexes of HEt₂dtfmbtu are reported. The ligand coordinates bidendate forming bis chelates. The Ni^II and the Pd^II complexes are isostructural. The also prepared Cu^II complex could not be characterized by X‐ray analysis. However, the preparation of diamagnetically diluted powders Cu/Ni(Et₂dtfmbtu)₂ and Cu/Pd(Et₂dtfmbtu)₂ suitable for EPR studies was successful. The EPR spectra of the Cu/Ni and Cu/Pd systems show noticeable differences for the symmetry of the CuS₂O₂ unit in both complexes: the Cu/Pd system is characterized by axially‐symmetric g< and A ^cu tensors; for the Cu/Ni system g and A ^Cu have rhombic symmetry. EPR studies on frozen solutions of the Cu^II complex show the presence of a Cu^II‐Cu^II dimer which is the first observed for Cu^II acylthioureato complexes up to now. The parameters of the fine structure tensor were used for the estimation of the Cu^II‐Cu^II distance.     

Acceleration of Correlation-corrected Vibrational Self-consistent Field Calculation Times for Large Polyatomic Molecules

Acceleration of the correlation-corrected Vibrational self-consistent field (CC-VSCF) method for anharmonic calculations of vibrational states of polyatomic molecules is described. The acceleration assumes pairwise additive interactions between different normal modes, and employs orthogonality of the single-mode vibrational wavefunctions. This greatly reduces the effort in computing correlation effects between different vibrational modes, which is treated by second order perturbation theory in CC-VSCF. The acceleration can improve the scaling of the overall computational effort from N ⁶ to N ⁴, where N is the number of vibrational modes. Sample calculation times, using semi-empirical potential surfaces (PM3), are given for a series of glycine peptides. Large computational acceleration, and significant reduction of the scaling of the effort with system size, is found and discussed.