Mechanistic insight into the structure and dynamics of entangled and hydrated λ-phage DNA

Intrinsic dynamics of DNA plays a crucial role in DNA-protein interactions and has been emphasized as a possible key component for in vivo chromatin organization. We have prepared an entangled DNA microtube above the overlap concentration by exploiting the complementary cohesive ends of λ-phage DNA, which is confirmed by atomic force microscopy and agarose gel electrophoresis. Photon correlation spectroscopy further confirmed that the entangled solutions are found to exhibit the classical hydrodynamics of a single chain segment on length scales smaller than the hydrodynamic length scale of single λ-phage DNA molecule. We also observed that in 41.6% (gm water/gm DNA) hydrated state, λ-phage DNA exhibits a dynamic transition temperature (T(dt)) at 187 K and a crossover temperature (T(c)) at 246 K. Computational insight reveals that the observed structure and dynamics of entangled λ-phage DNA are distinctively different from the behavior of the corresponding unentangled DNA with open cohesive ends, which is reminiscent with our experimental observation.     

Simultaneous quantification of abemaciclib and letrozole in rat plasma: method development,validation and pharmacokinetic application

Treatment through a combination of drugs involving cyclin D-dependent kinase inhibitors like abemaciclib and aromatase inhibitor like letrozole proved to be a potential therapeutic regimen and first-line treatment in estrogen receptor-positive breast cancer. In this study, we developed a simple and simultaneous RP-HPLC bioanalytical method for quantifying abemaciclib and letrozole in rat plasma. Abemaciclib and letrozole were separated on Zorbax Eclipse C₁₈ column employing a gradient elution method comprising 10 mM ammonium acetate (pH 5) and acetonitrile as mobile phase. The method was found to have acceptable selectivity, accuracy (97.20–118.17%), precision (1.10–9.39%) and stability in the validation experiment performed as per the US Food and Drug Administration guidelines. The method sensitivity was low at a concentration level of 100 ng/ml. The applicability of the method has been verified through a single-dose oral pharmacokinetic study in rat. The developed method will be useful to quantitate the analytes in rat plasma samples of different preclinical studies including their pharmacokinetic drug–drug interactions in the future. To date, no method has been reported for the quantification of abemaciclib and letrozole simultaneously in any type of biological matrices. Therefore, this study makes a definite significant contribution in the field of bioanalytical research.     

A simple approach to evaluation of lattice sums

It is shown that starting from a Fourier transform relation one can derive, in a surprisingly simple manner, all the well-known results of lattice summation, that have been obtained so far by a complicated use of the Ewald theta transformation. We show that the Ewald transformation follows directly from the Fourier transform relation.     

Kinetics of oxidation of methanol and mono-deutero-methanol by chromium(VI) in perchloric acid medium

Kinetics of the oxidation of methanol and mono-deutero-methanol by Cr(VI) over a wide range of temperature (25–40°) have been studied in perchloric acid medium at constant ionic strength (μ = 1.0 M) adjusted with sodium perchlorate. Each reaction is first order with respect to the substrate and dichromate concentrations but the order with respect to [H⁺] is nearly 3 in each case. Both these reactions take place at almost the same rate under identical experimental conditions. The activation parameters of the reactions are not widely different and the values of ΔH3 and ΔS3 for the oxidation of methanol are 79.5 kJ mole ^-1 and - 38.1 J deg^-1 mole^-1 respectively, whereas the corresponding values for the deuterated compound are 83.8 kJ mole^-1 and -23.9 J deg^-1 mole^-1. The probable mechanism of the reactions is discussed.     

Multicomponent gas separation by an asymmetric permeator containing two different membranes

A numerical analysis of an asymmetric permeator containing two different kinds of membranes and capable of separating a ternary feed gas mixture into three product streams has been carried out. For negligible axial pressure drops in the gas streams, equations have been developed and calculation methods illustrated for four flow patterns: cross, parallel, countercurrent and perfectly mixed. The main parameters used in the analysis are pressure ratios, the ratio of the two membrane areas and the permeabilities. Results have been presented for a 50% H₂10% CO₂40% N₂ feed with a permeator having one cellulose acetate (CA) type membrane and one silicone membrane. For both permeate streams, countercurrent achieves highest permeate qualities and requires least membrane area amongst all four flow patterns. The presence of a silicone membrane produces a richer H₂ permeate from the CA membrane than that from a CA-membrane-alone configuration. Simultaneously, an enriched CO₂ permeate is obtained from the silicone membrane. Under the ideal condition of zero pressure ratios, the asymmetric permeator has also been evaluated against the series configuration of a permeator containing a CA membrane only followed by a permeator containing only a silicone (S) membrane. The asymmetric configuration usually performs better than this series configuration for the chosen range of parameters.     

The volume measure for flat connections as limit of the Yang–Mills measure

We prove that integration over the moduli space of flat connections can be obtained as a limit of integration with respect to the Yang–Mills measure defined in terms of the heat-kernel for the gauge group. In doing this we also give a rigorous proof of Witten’s formula for the symplectic volume of the moduli space of flat connections. Our proof uses an elementary identity connecting determinants of matrices along with a careful accounting of certain dense subsets of full measure in the moduli space.     

A Comparative Study of Proton-Emulsion and Heavy-Ion-Emulsion Interactions at 4.5 GeV/c per Nucleon

This paper presents a comparative study of inelastic interactions of proton-Emulsion, ¹²C-Emulsion and ²⁴Mg-Emulsion at 4.5 GeV/c per nucleon. The multiplicity distribution and their correlations have been studied. A strong correlation between 〈n_s〉 and n_h in case of ²⁴Mg-Emulsion and ¹²C-Emulsion is observed which is not so in the case of proton-Emulsion interaction. It is also observed that 〈n_s〉 increases with the increase of the projectile mass. The angular distribution of the target fragments in ²⁴Mg-Emulsion and ¹²C-Emulsion interactions show massive forward collimations. Comparison is also made in the pseudorapidity distributions of ²⁴Mg-Emulsion, ¹²C-Emulsion and proton-Emulsion interactions. The result shows many interesting features.     

MHD flow of two immiscible visco-elastic Rivlin-Ericksen fluids through a non-conducting rectangular channel in presence of transient pressure gradient

The aim of this paper is to investigate the problem of MHD flow of two immiscible viscoelastic Rivlin-Ericksen fluids through a non-conducting rectangular channel in presence of transient pressure gradient. Appropriate to the boundary conditions of the problem the solution is derived by variable separation technique. Using this solution the interface velocity, flux, skin friction and mean velocity are derived. In absence of the magnetic field and the elastic behaviour the corresponding classical problem can be derived.