A high‐throughput LC–MS/MS method for determination of flunarizine in human plasma: Pharmacokinetic study with different doses

A high‐throughput and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the determination of flunarizine in human plasma. Liquid–liquid extraction under acidic conditions was used to extract flunarizine and flunarizine‐d8 from 100 μL human plasma. The mean extraction recovery obtained for flunarizine was 98.85% without compromising the sensitivity of the method. The chromatographic separation was performed on Hypersil Gold C₁₈ (50 × 2.1 mm, 3 μm) column using methanol–10 mm ammonium formate, pH 3.0 (90:10, v/v) as the mobile phase. A tandem mass spectrometer (API‐5500) equipped with an electrospray ionization source in the positive ion mode was used for detection of flunarizine. Multiple reaction monitoring was selected for quantitation using the transitions, m/z 405.2 → 203.2 for flunarizine and m/z 413.1 → 203.2 for flunarizine‐d8. The validated concentration range was established from 0.10 to 100 ng/mL. The accuracy (96.1–103.1%), intra‐batch and inter‐batch precision (CV ≤ 5.2%) were satisfactory and the drug was stable in human plasma under all tested conditions. The method was used to evaluate the pharmacokinetics of 5 and 10 mg flunarizine tablet formulation in 24 healthy subjects. The pharmacokinetic parameters C_max and AUC were dose‐proportional.     

A Tachyonic Scalar Field with Mutually Interacting Components

We investigate the tachyonic cosmological potential V(?) in two different cases of the quasi-exponential expansion of universe and discuss various forms of interaction between the two components—matter and the cosmological constant—of the tachyonic scalar field, which lead to the viable solutions of their respective energy densities. The distinction among the interaction forms is shown to appear in the O _m (x) diagnostic. Further, the role of the high- and low-redshift observations of the Hubble parameter is discussed to determine the proportionality constants and hence the correct form of matter–cosmological constant interaction.     

Reduction of uranyl nitrate ions in a continuous flow electrochemical reactor

In a contemporary salt-free flowsheet of nuclear fuel reprocessing, uranous ions are used as a reducing agent to accomplish the separation of uranium and plutonium from each other which is normally produced electrochemically. In the present study, continuous mode electrochemical reduction of uranyl ions in nitric acid medium and in the presence of hydrazine nitrate was carried out in a divided cell at three different feed flow rates and cathodic current densities for the purpose of optimizing the process conditions for better conversion efficiency. A correlation function is described as a mathematical model in which, mass transfer parameter is expressed as a function of current density and flow rate. From the multivariable nonlinear regression of the experimental data, rate parameter was determined. The electro reduction of uranyl ions was not influenced by the initial acidity. The maximum conversion rate of 87 % was obtained for the electro-reduction of 100 g/l U(VI) in 3 M nitric acid with feed flow rate as 0.3 l/h and current density as 15 mA/cm². The results for the reduction of 100 g/l uranyl ions indicate that an optimum flow rate of about 0.5 l/h and 15 mA/cm² as cathodic current density may suffice for the conversion with efficiency better than 60 %. The calculated steady state concentrations for U(IV) were found to be in good agreement with the experimental results.     

Enhancement of Non-Gaussianity and Nonclassicality of Photon-Added Displaced Fock State: A Quantitative Approach

Non-Gaussian and nonclassical states and processes are already found to be important resources for performing various tasks related to quantum gravity and quantum information processing. Considering these facts, a quantitative analysis of the nonclassical and non-Gaussian features is performed here for photon added displaced Fock state, as a test case, using a set of measures, namely entanglement potential, Wigner–Yanese skew information, Wigner logarithmic negativity, and relative entropy of non-Gaussianity. It is observed that Fock parameter always increases the amount of nonclassicality and non-Gaussianity, while photon addition is effective only for small values of the displacement parameter. Further, the nonclassical and non-Gaussian effects decrease initially with an increase in the displacement parameter before increasing for the large displacement to saturate to the corresponding Fock state (equivalently displaced Fock state) value. Finally, dynamics of the Wigner function under the effect of photon loss channel is used to show that only highly efficient detectors are able to detect Wigner negativity.     

Quasiprobability distributions in open quantum systems: Spin-qubit systems

We study nonclassical features in a number of spin-qubit systems including single, two and three qubit states, as well as an N$N$ qubit Dicke model and a spin-1 system, of importance in the fields of quantum optics and information. This is done by analyzing the behavior of the well known Wigner, P$P$, and Q$Q$ quasiprobability distributions on them. We also discuss the not so well known F$F$ function and specify its relation to the Wigner function. Here we provide a comprehensive analysis of quasiprobability distributions for spin-qubit systems under general open system effects, including both pure dephasing as well as dissipation. This makes it relevant from the perspective of experimental implementation.     

From polyelectrolyte to polyampholyte microgels: comparison of swelling properties

We report the results of comparative studies of the swelling behavior of polyelectrolyte (PE) and polyampholyte (PA) microgels in response to pH, ionic strength, temperature, and solvent composition. Polyelectrolyte microgels used were cross-linked binary copolymers of poly(N-isopropylacrylamide) (polyNIPAm) and acrylic acid (AA) or vinyl imidazole (VI). The PA microgels with an excess of either cationic or anionic groups swelled at low or high pH values, respectively, analogous to PE microgels. The PA microgels with similar amounts of AA and VI groups exhibited marked swelling at both high and low pH values. All PA microgels shrank in the intermediate range of pH due to electrostatic attraction between charged AA and VI moieties. In moderately concentrated salt solutions, PA microgels underwent swelling showing antipolyelectrolyte behavior. The extent of swelling of PA microgels increased with rise in AA content. The temperature-dependent contraction of both PE and PA microgels occurred at higher temperatures when AA and VI groups were charged and hydrophilic. Ion pairing between the AA and VI groups increased the extent of the temperature-induced deswelling in PA microgels. The solvent-dependent swelling of PE and PA microgels in ethanol–water mixtures was governed by competing electrostatic and cosolvency effects.

Interaction of peroxyformic acid with water molecules: a first-principles study

The present article comprises a theoretical study of structures and energetics of the lowest energy conformers of peroxyformic acid (PFA) and its hydrated variants, viz. PFA...(H2O)n (n = 1-4), at the molecular level. We have employed two different ab initio quantum chemical methods, viz. restricted Hartree-Fock (RHF) and the second-order M?ller-Plesset (MP2) perturbation theory with the basis sets 6-31G(d,p) and 6-311++G(2d,2p). Modifications in the structure as well as vibrational frequencies of PFA brought about by successive addition of H2O molecules are also discussed. Cooperativity of hydrogen bonding in these clusters can be gauged through a detailed many body interaction energy analysis.