Instabilities Driven by an Intense Beam in a Plasma-Filled Dielectric-Lined Waveguide Immersed in a Finite Axial Magnetic Field

A linear analysis is described on stabilities driven by an intense relativistic electron beam in an infinitely long, plasma-filled, and dielectric-lined circular waveguide immersed in a finite strength axial magnetic field. A dispersion equation is derived from the cold fluid theory and solved numerically. Beam-plasma instabilities due to interaction between beam modes and the Trivelpiece-Gould modes appear as well as the Cherenkov and the cyclotron Cherenkov instabilities. Parametric researches are carried out varying magnetic field strength, plasma density, and dielectric constant. Effects of a finite magnetic field and plasma filling are discussed in connection with the possibilities of using this system as a microwave radiation source.     

A simple HPLC method for simultaneous determination of lopinavir,ritonavir and efavirenz

We developed a simple HPLC method for the simultaneous determination of lopinavir (LPV), ritonavir (RTV) and efavirenz (EFV) to evaluate the efficiency of co-administration of LPV/RTV and EFV in Japanese patients enrolled in a clinical study. The monitoring of LPV plasma concentration is important because co-administration of LPV/RTV with EFV sometimes decreases plasma concentrations of LPV caused by EFV activation of cytochrome P-450 3A. A solution of acetonitrile, methanol and tetramethylammonium perchlorate (TMAP) in dilute aqueous trifluoroacetic acid (TFA) has been used as the mobile phase in a HPLC method to elute LPV and RTV. We found that a solvent ratio of 45 : 5 : 50 (v/v/v) of acetonitrile/methanol/0.02 M TMAP in 0.2% TFA optimized separation of LPV, RTV and EFV. A column temperature of 30 degrees C was necessary for the reproducibility of the analyses. Standard curves were linear in the range 0.060 to 24.06 micro g/ml for LPV, 0.010 to 4.16 micro g/ml for RTV, and 0.047 to 37.44 micro g/ml for EFV. Coefficients of variation (CVs) of LPV, RTV and EFV in intraday and interday assays ranged from 1.5 to 4.0%, 2.5 to 16.8% and 1.0 to 7.7%, respectively. Accuracies ranged from 100 to 110%, 101 to 116% and 99 to 106% for LPV, RTV and EFV, respectively. The extraction recoveries were 77-87, 77-83 and 81-91% for LPV, RTV and EFV, respectively.     

Synthesis and Preliminary Evaluation of 2-Chloroethylnitrosourea Derivatives of Sucrose

Abstract

2-Chloroethylnitrosourea derivatives of sucrose have been synthesized as potential antineoplastic agents. Two compounds: 6-[[[(2-chloroethyl)nitrosoamino]carbonyl]amino]-6-deoxysucrose and 6′-[[[(2-chloroethyl)nitrosoamino]carbonyl]amino]-6′-deoxysucrose exhibited significant antitumor activity against experimental leukemia L1210 in mice. Their chemical decomposition rates (T_0.5) have been determined.     

Non-superaromatic reference for carbon nanotube as a quasi-one-dimensional π-bonding model for graphite

A non-superaromatic reference defined for an armchair tubule is proposed as a simple model for the graphite -electron system. This kind of reference structure is easy to deal with because of its quasi-one-dimensional character. We found that even the non-superaromatic reference for a relatively thin armchair tubule has essentially the same -binding energy per carbon atom as graphite. The accurate -binding energy per carbon atom of graphite turned out to be 1.57459724.