Rapid ultraperformance liquid chromatography–tandem mass spectrometry method for quantification of oxcarbazepine and its metabolite in human plasma

A rapid and sensitive ultraperformance liquid chromatography tandem mass spectrometry assay was developed for the simultaneous analysis of oxcarbazepine and its main metabolite in human plasma. The assay involves a simple solid‐phase extraction procedure of 0.3 mL of human plasma and analysis was performed on a triple‐quadrupole tandem mass spectrometer in multiple reaction monitoring mode via electrospray ionization. Separation was achieved on an Acquity UPLC™ BEH C₁₈ column (50 × 2.1 mm, i.d., 1.7 µm) with isocratic elution at a flow‐rate of 0.25 mL/min and imipramine was used as the internal standard. The standard calibration curve was linear over the range 9.580–5070.205 ng/mL for oxcarbazepine (OXC) and 19.444–10290.800 ng/mL for 10,11‐dihydro‐10‐hydroxycarbamazepine (MHD), expressed by the linear correlation coefficient r², which was better than 0.995 for OXC and MHD. The intra‐ and inter‐day precision and accuracy of the quality control samples were within 10.0%. The recoveries were 81.0, 89.6 and 66.6% for OXC, MHD and imipramine, respectively. The total run time was 1.5 min only for each sample, which makes it possible to analyze more than 350 samples per day. Copyright © 2010 John Wiley & Sons, Ltd.     

A system mean void fraction model for predicting various transient phenomena associated with two-phase evaporating and condensing flows

The system mean void fraction model's principle virtue is its simplicity. The model converts the two-phase evaporating or condensing flow system into a type of lumped parameter system, generally yielding simple, closed form solutions in terms of the important system parameters. The particular applications of the model which are demonstrated in this paper are for a class of transient flow problems where complete vaporization or condensation takes place, and where the system mean void fraction can be considered to be time-invariant. This assumption uncouples the problem from the transient form of the momentum principle, an analytical simplification of considerable magnitude. The specific transients under consideration are caused by changes in the inlet flowrate. For evaporating flows, these transients are the effective liquid dry-out point, and the outlet flowrate of superheated vapor. For condensing flows, they are the effective point of complete condensation, and the outlet flowrate of subcooled liquid.     

Clouding Behavior and Thermodynamic Study of Nonionic Surfactants in Presence of Additives

The present study investigates the effect of different additives on the cloud point (CP) of nonionic surfactants Triton X-100 (TX-100) and Triton X-114 (TX-114) in aqueous solutions. The thermodynamic parameters of these mixtures were calculated at different additive concentrations. The cloud point of nonionic surfactants TX-100 and TX-114 decreased with the increment of electrolyte concentrations and increased with alcohol concentrations. The standard Gibbs free energy was found to be positive for both the surfactants, whereas the enthalpy and the entropy of the clouding phenomenon were found to be positive with alcohols and negative with electrolytes. The overall clouding process was endothermic for alcohols and exothermic for electrolytes.     

Synthesis and NMR elucidation of novel amino acid cavitand derivatives

The synthesis of seven novel protected amino acid cavitands is reported. All have four pendant n-undecyl chains and ‘headgroups’ connected by a two-carbon spacer at four positions on the aromatic rings. The amino acids employed are glycine, alanine, phenylalanine, leucine, proline, tryptophan, serine, glutamine and lysine. The structures of the compounds were elucidated using one- and two-dimensional NMR techniques, which verified that all tetra-substituted cavitands have symmetrical C_4v conformation. This is the first example of a complete study for amino acid cavitand derivatives.     

Realizing universal edge properties in graphene fractional quantum Hall liquids

Universal chiral Luttinger liquid behavior has been predicted for fractional quantum Hall edge states, but so far has not been observed experimentally in semiconductor-based two-dimensional electron gases. One likely cause of this absence of universality is the generic occurrence of edge reconstruction in such systems, which is the result of a competition between confinement potential and Coulomb repulsion. We show that due to a completely different mechanism of confinement, edge reconstruction can be avoided in graphene, which allows for the observation of the predicted universality.     

Sufficiency and strong commutants in quantum probability theory

A probability algebra (A, *, ω) consisting of a^*algebraA with a faithful state ω provides a framework for an unbounded noncommutative probability theory. A characterization of symmetric probability algebra is obtained in terms of an unbounded strong commutant of the left regular representation ofA. Existence of coarse-graining is established for states that are absolutely continuous or continuous in the induced topology. Sufficiency of a^*subalgebra relative to a family of states is discussed in terms of noncommutative Radon-Nikodym derivatives (a form of Halmos-Savage theorem), and is applied to couple of examples (including the canonical algebra of one degree of freedom for Heisenberg commutation relation) to obtain unbounded analogues of sufficiency results known in probability theory over a von Neumann algebra.     

Development of a terminal voltage stabilization system for the FOTIA at BARC

A terminal voltage stabilization system for the folded tandem ion accelerator (FOTIA) was developed and is in continuous use. The system achieves good voltage stabilization, eliminates ground loops and noise interference. It incorporates a correcting circuit for compensating the mains frequency variations in the GVM amplifier circuit. The present system has two modes of operation namely GVM control mode and slit control mode. A voltage stability of about ± 2 kV has been achieved. In this paper, some of the salient features of the voltage stabilization system are discussed.     

A note on generalized characters

For a compactly generated LCA group G, it is shown that the setH(G) of all generalized characters on G equipped with the compact-open topology is a LCA group andH(G) = Ĝ (the dual group ofG) if and only ifG is compact. Both results fail for arbitrary LCA groups. Further, ifG is second countable, then the Gel’fand space of the commutative convolution algebraC _c (G) equipped with the inductive limit topology is topologically homeomorphic toH(G).     

Bilateral generating functions for Jacobi polynomials

In this paper, we have obtained three theorems on generating functions. We derive from these theorems a large number of bilateral generating functions for Jacobi polynomials. Certain interesting expansions of triple hypergeometric series are also obtained from one of the theorems.     

Low temperature conductivity of doped semiconductors: Mass anisotropy and intervalley effects

The theory of the low temperature correction to the conductivity of weakly disordered three-dimensional systems due to electron-electron interaction effects is extended to the case of many valley systems (e.g., n-doped Si or Ge). A strong dependence due to both mass anisotropy and intervalley scattering is found, which is capable of explaining the large discrepancy between the experiment and existing theoretical estimates.