An LC method for quantifying bepridil in human plasma using 1-naphthol as the internal standard

A modified method for the quantitative determination of bepridil hydrochloride in human plasma is described. This method is unrelated to chemical methods currently in use. The mobile phase is 50 mM phosphate buffer (pH3.0)-methanol-acetonitrile-triethylamine (57:3:40:1, v/v), and the samples are fractionated on a C8-3 column (150 × 4.6 mm, 5 μm) using a flow rate of 0.9 mL/min. Bepridil was detected by UV spectroscopy at 254 nm. The retention times of bepridil and 1-naphthol were 12.6 min and 7.5 min, respectively; there was no interference originating from human plasma. We confirmed that the bepridil and 1-naphthol peaks were not influenced by the presence of 32 commercial medicines frequently co-administered with bepridil. Additionally, the concentration of bepridil in the plasma of five patients treated with bepridil for atrial fibrillation was measured. These samples were collected just before each dosage of bepridil. Their rhythm and rate control were well maintained. Trough concentrations ranged from 233.9 to 347.4 ng/mL, similar to previously reported values.     

Mathematical approach for the dynamic testing technique

In dealing with phenomena which show a linear response such as viscoelastic or dielectric properties, measurements are carried out by observing the relationship between the stimulus applied to the sample and the response from the sample. Since the Fourier analysis technique is effective in obtaining this relationship, two types of circuitries based on Fourier analysis have been created. Both DMA and dielectric measurement were used to evaluate these circuitries. Results were satisfactory, especially with respect to tanδ precision.

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Zusammenfassung Bei der Arbeit mit Erscheinungen, die wie z.B. viskoelastische oder dielektrische Eigenschaften eine lineare Reaktion zeigen, wurden Messungen durch Beobachtung der Beziehung zwischen der auf die Probe angewendeten Aktion und der von der Probe gezeigten Reaktion durchgeführt. Da die Fourier-Analyse eine effektive Technik zur Ermittlung dieser Beziehung ist, wurden auf der Grundlage der Fourier-Analyse zwei Typen von Schemen geschaffen. Sowohl DMA als auch dielektrische Messungen wurden zur Entwicklung dieser Schemen verwendet. Did Resultate waren zufriedenstellend, insbesondere mit Hinblick auf die Genauigkeit von tanδ.

     

Single-electron-capture cross sections for 0.4–5.0 keV He+ ions incident on alkali-vapor targets

Total cross sections for single-electron capture by He⁺ ions in vapor targets of Cs, Rb, K and Na have been determined in the energy range 0.4–5.0 keV. The energy dependence of the cross-section curves is very similar for all the targets. The cross sections for all the targets are maximum at about the same energy, 1.5 keV. Comparison is made with other reported experimental and theoretical results.     

The regioselective alkylation of 4,6-dimethyl-1-phenyl-2(1H)-pyrimidinone

4,6-Dimethyl-1-phenyl-2(1H)-pyrimidinone (I) was treated with alkyl halides in the presence of sodium hydride at low temperature to afford only C-6 alkylated products III and IV in good yields. Further, the mono-, IIIa-d, and di-alkylated 2(1H)-pyrimidinones IVa-d were selectively obtained by changing the amount of alkyl halides.     

The crystal structure of Mg51Zn20

The crystal structure of Mg₅₁Zn₂₀, a phase designated conventionally as “Mg₇Zn₃,” has been determined by the single-crystal X-ray diffraction method. It was solved by the examination of a Patterson synthesis, and refined by the ordinary Fourier and least-squares method; the R value obtained was 4.8% for 1167 observed reflections. The crystal is orthorhombic, space group Immm, with a = 14.083(3), b = 14.486(3), c = 14.025(3) Å, and Z = 2. There are 18 independent atomic sites, Zn1Zn6, Mg1Mg10, A, and B, and the last two sites are statistically occupied by Zn and Mg atoms with the occupancies; 0.46(2)Zn7 + 0.52(2)Mg11 and 0.24(2)Zn8 + 0.74(2)Mg12, for A and B, respectively. The structure of the crystal is described as an arrangement of icosahedral coordination polyhedra, to which all the atomic sites but Zn3 site belong. In this arrangement the Zn atoms other than the Zn3 and Zn8(B) center the icosahedral coordination polyhedra with coordination number 12. The Zn3, Zn8 atoms, and all the Mg atoms except Mg11(A) are located at the centers of various coordination polyhedra with the coordination numbers from 11 to 15. The distances between neighboring atoms are 2.71–3.07, 2.82–3.65, and 2.60–3.20 Å for ZnZn, MgMg, and ZnMg, respectively.     

Spallation of niobium by 12 GeV protons

Cross sections for the production of approximately 50 radionuclides in the interaction of niobium with 12 GeV protons were determined by the activation technique. The results were parametrized in terms of a 6-parameter equation which reproduced the measured charge-dispersion and mass-yield curves.     

Notes on the Problem of the Allocation of Resources to Activities in Discrete Quantities

The simple resource allocation problem (also called the distribution of effort problem) is generalized by allowing more than one resource constraint. It is shown that the generalized problem can be reduced to the simple one if the coefficients in the objective function are all unity. In general, however, the problem seems to become much more difficult; the difficulty is evidenced by the failure of the incremental method which is valid for the simple problem, and the NP-hardness of the generalized problem.     

Remaining noise-induced spatiotemporal dynamics in a free electron laser stabilized by feedback control

We investigate the efficiency of the pulsed regime stabilization by feedback control in a free electron laser (FEL) in oscillator configuration. We show that a hidden dynamics remains in the controlled FEL. Though not visible in the evolution of the pulse envelope, this dynamics affects the internal pulse shape evolution, and thus the FEL spectrum and coherence properties. The experimental results obtained on the UVSOR FEL are interpreted in the framework of a field master equation model. The stochastic nature of spontaneous emission is taken into account, and appears as an essential ingredient since the dynamics of the controlled structures is governed by noise like the other stable regimes of the FEL.     

Sequential pericyclic reaction of ene-diallenes: an efficient approach to the steroid skeleton

[reaction: see text] The one-pot construction of polycyclic aromatic systems from acyclic ene-bis(propargyl alcohols) was achieved through a tandem dual [2,3]-sigmatropic rearrangement/6pi-electrocyclic reaction/intramolecular [4 + 2] cycloaddition sequence. A steroidal compound was conveniently synthesized using the present method.