Development and validation of LC‐MS/MS method for the estimation of β‐hydroxy‐β‐methylbutyrate in rat plasma and its application to pharmacokinetic studies

A simple, sensitive and specific high‐performance liquid chromatography mass spectrometry (LC‐MS/MS) method was developed and validated for the quantification of β‐hydroxy‐β‐methyl butyrate (HMB) in small volumes of rat plasma using warfarin as an internal standard (IS). The API‐4000 LC‐MS/MS was operated under the multiple reaction‐monitoring mode using the electrospray ionization technique. A simple liquid–liquid extraction process was used to extract HMB and IS from rat plasma. The total run time was 3 min and the elution of HMB and IS occurred at 1.48 and 1.75 min respectively; this was achieved with a mobile phase consisting of 0.1% formic acid in a water–acetonitrile mixture (15:85, v/v) at a flow rate of 1.0 mL/min on a Agilent Eclipse XDB C₈ (150 × 4.6, 5 µm) column. The developed method was validated in rat plasma with a lower limit of quantitation of 30.0 ng/mL for HMB. A linear response function was established for the range of concentrations 30–4600 ng/mL (r > 0.998) for HMB. The intra‐ and inter‐day precision values for HMB were acceptable as per Food and Drug Administration guidelines. HMB was stable in the battery of stability studies, viz. bench‐top, autosampler freeze–thaw cycles and long‐term stability for 30 days in plasma. The developed assay method was applied to a bioavailability study in rats. Copyright © 2012 John Wiley & Sons, Ltd.     

Conservation of a resource based fishery through optimal taxation

In the present paper, we study a dynamic reaction model in which (i) the predator is provided with an alternative food in addition to the prey species, (ii) the predator is harvested, and (iii) a tax is imposed to regulate the system. The existence of possible steady states along with their local as well as global stability is discussed for both the exploited and unexploited systems. Boundedness of the system is also discussed. It is seen that the system undergoes a Hopf bifurcation by the addition of alternative prey and the criteria for the Hopf-bifurcation is also discussed. Optimal tax policy is discussed using Pontryagin’s maximal principle. Finally, some numerical simulations are given to show the consistency with theoretical analysis.     

A Simple and New Synthetic Method for the Preparation of 2-Pheynl-6-substituted Quinolines

2-Phenylquinoline derivatives have been synthesized through the thermolysis of suitable enaminoimine hydrochiorides.     

Peptide‐poly(ε‐caprolactone) biohybrids by grafting‐from ring‐opening polymerization: Synthesis,aggregation, and crystalline properties

Well‐defined peptide‐poly(ε‐caprolactone) (Pep‐PCL) biohybrids were successfully synthesized by grafting‐from ring‐opening polymerization (ROP) of ε‐caprolactone (CL) using designed amine‐terminated sequence‐defined peptides as macroinitiators. MALDI‐TOF‐MS and ¹H NMR analyses confirmed the successful attachment of peptide to the PCL chain. The gel permeation chromatography (GPC) measurement showed that the Pep‐PCL biohybrids with controllable molecular weights and low polydispersities (PDI <1.5) were obtained by this approach. The aggregation of Pep‐PCL hybrid molecules in THF solution resulted in the formation of micro/nanospheres as confirmed through FESEM, TEM, and DLS analyses. The circular dichroism study revealed that the secondary structure of peptide moiety was changed in the peptide‐PCL biohybrids. The crystallization and melting behavior of Pep‐PCL hybrids were somewhat changed compared with that of neat PCL of comparable molecular weight as revealed by DSC and XRD measurements. In Pep‐PCL biohybrids, extinction rings were observed in the PCL spherulites, in contrast with the normal spherulite morphology of the neat PCL. There was a substantial decrease (4–5 folds) in the spherulitic growth rate after the incorporation of peptide moiety at the end of PCL chain as measured by polarizing optical microscopy. Pseudomonas lipase catalyzed enzymatic degradation was studied for Pep‐PCL hybrids and neat PCL. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Recovery of plutonium and cerium from alumina crucible

Journal of Radioanalytical and Nuclear Chemistry - Plutonium recovery is inevitable from plutonium bearing alumina crucibles generated over the years as part of carbon analysis during chemical...     

Almost global attitude consensus of multi-agent rigid bodies on $$\mathrm{TSO}(3)^N$$ TSO ( 3 ) N in the presence of disturbances and directed topology

Nonlinear Dynamics - The article proposes a distributed attitude consensus algorithm for multi-agent rigid bodies on the tangent bundle $$\mathrm{TSO}(3)^N$$ . It is assumed that a directed fixed...     

Kinetics of Early Decomposition Stages in Diluted bcc Fe–Сu–Ni–Al Alloy: MC+MD Simulation

Physics of the Solid State - A combined approach including the Monte Carlo and molecular-dynamics simulation, decomposition kinetics and segregation formation in the multicomponent low-alloy...