Analysis of Azithromycin in Human Plasma by LC–MS–MS

A simple sensitive and selective liquid chromatographic–tandem mass spectrometric method was developed and validated for the quantification of azithromycin in human plasma. Roxithromycin was used as the internal standard. The chromatographic separation was performed on a SunFire C18, 50 mm × 2.1, 3.5 μm column at 30 °C with mobile phase consisted of 1.54 g ammonium acetate, 250 mL water, 570 mL acetonitrile, 180 mL methanol and 0.6 mL glacial acetic acid. Flow rate was 0.2 mL min⁻¹. The work-up procedure involved a liquid–liquid extraction of the compounds. Mass spectrometric data were acquired in single ion monitoring. MRM mode of the ions 749.58 > 591.6 and 837.64 > 158.2 for azithromycin and roxithromycin, respectively. The method was validated in the concentration range of 2–1,000 ng mL⁻¹. Absolute recovery of azithromycin was 81.97%. Retention time for azithromycin was 0.9 and 1.1 min for roxithromycin. The run time was 2 min. This method was found suitable to analyse human plasma samples for application in pharmacokinetic, pharmacodynamic, bioavailability/bioequivalance studies.

     

Evidence for symplectic symmetry in Ab initio no-core shell model results for light nuclei

Clear evidence for symplectic symmetry in low-lying states of 12C and 16O is reported. Eigenstates of 12C and 16O, determined within the framework of the no-core shell model using the J-matrix inverse scattering potential with A相似文献   

Dynamic pricing and scheduling in a multi-class single-server queueing system

This paper investigates an optimal sequencing and dynamic pricing problem for a two-class queueing system. Using a Markov Decision Process based model, we obtain structural characterizations of optimal policies. In particular, it is shown that the optimal pricing policy depends on the entire queue length vector but some monotonicity results prevail as the composition of this vector changes. A numerical study finds that static pricing policies may have significant suboptimality but simple dynamic pricing policies perform well in most situations.     

Application of fuzzy optimization to a supply chain network design: A case study of an edible vegetable oils manufacturer

This study applies fuzzy sets to integrate the supply chain network of an edible vegetable oils manufacturer. The proposed fuzzy multi-objective linear programming model attempts to simultaneously minimize the total transportation costs. The first part of the total transportation costs is between suppliers and silos; and rest one is between manufacturer and warehouses. The approach incorporates all operating realities and actual flow patterns at production/distribution network with reference to demands of warehouses, capacities of tin and pet packaging lines. The model has been formulated as a multi objective linear programming model where data are modeled by triangular fuzzy numbers. Finally, the developed fuzzy model is applied for the case study, compiled the results and discussed.     

Surface Acidity of H-Birnessite: Infrared Spectroscopic Study of Formic Acid Decomposition

This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-birnessite sample. Changes in the surface and structure were characterized using infrared spectroscopy, N₂ gas adsorption–desorption, and thermal analysis techniques. The acid sites of H-birnessite were investigated by infrared and thermal analysis using pyridine as a molecular probe. Decomposition of formic acid started on H-birnessite at 120°C and was complete at 400°C. Infrared spectra revealed that the molecularly adsorbed formic acid species were transformed to a formate species, and the formate species were transformed to CO. The most stable adsorption structure for formic acid was found as a molecular monodentate configuration.     

Electrochemical Biosensor Design with Multi-walled Carbon Nanotube to Display DNA-Schiff Base Interaction

This paper demonstrates a Schiff base i. e. 5-(diethylamino)-2-((2,6-diethylphenylimino)methyl)phenol (5-DDMP) that was sensed by DNA biosensor. dsDNA was immobilized onto GCE modified with functionalized multi-walled carbon nanotubes to prepare a biosensor. The efficiency of dsDNA biosensor was determined and binding of 5-DDMP with dsDNA was searched by UV-vis spectrophotometry and differential pulse voltammetry. Molecular docking simulations between 5-DDMP and dsDNA were explored and as a result, a hydrogen bond and a π-π contact were observed between 5-DDMP and deoxyguanosine base (dG22) of the strand B, deoxyadenosine base (dA5) of the strand A, respectively. These studies could be useful for new anticancer drug design and development.     

Hydrogen-bonded and π-stacked nickel(II) thiosemicarbazone complexes: Synthesis,spectral and structural studies

Transition Metal Chemistry - Mixed ligand Ni(II) complexes were synthesized from triphenylphosphine and S-methyl- or S-ethyl-isothiosemicarbazone ligands derived from...     

A numerical investigation of energy dissipation with a shallow depth sloshing absorber

A liquid sloshing absorber consists of a container, partially filled with liquid. The absorber is attached to the structure to be controlled, and relies on the structure’s motion to excite the liquid. Consequently, a sloshing wave is produced at the liquid free surface within the absorber, possessing energy dissipative qualities. The behaviour of liquid sloshing absorbers has been well documented, although their use in structural control applications has attracted considerably less attention.     

A bicriteria parallel machine scheduling with a learning effect of setup and removal times

In studies on scheduling problems, generally setup times and removal times of jobs have been neglected or by including those into processing times. However, in some production systems, setup times and removal times are very important such that they should be considered independent from processing times. Since, in general jobs are done according to automatic machine processes in production systems processing times do not differ according to process sequence. But, since human factor becomes influential when setup times and removal times are taken into consideration, setup times will be decreasing by repeating setup processes frequently. This fact is defined with learning effect in scheduling literature. In this study, a bicriteria m-identical parallel machines scheduling problem with a learning effect of setup times and removal times is considered. The objective function of the problem is minimization of the weighted sum of total completion time and total tardiness. A mathematical programming model is developed for the problem which belongs to NP-hard class. Results of computational tests show that the proposed model is effective in solving problems with up to 15 jobs and five machines. We also proposed three heuristic approaches for solving large jobs problems. According to the best of our knowledge, no work exists on the minimization of the weighted sum of total completion time and total tardiness with a learning effect of setup times and removal times.     

A result on the sum of element orders of a finite group

Let G be a finite group and $$\psi (G)=\sum _{g\in {G}}{o(g)}$$. There are some results about the relation between $$\psi (G)$$ and the structure of G. For instance, it is proved that if G is a group of order n and $$\psi (G)>\dfrac{211}{1617}\psi (C_n)$$, then G is solvable. Herzog et al. in (J Algebra 511:215–226, 2018) put forward the following conjecture: Conjecture. If G is a non-solvable group of order n, then $$\begin{aligned} {\psi (G)}\,{\le }\,{{\dfrac{211}{1617}}{\psi (C_n)}}, \end{aligned}$$with equality if and only if $$G \cong A_5$$. In particular, this inequality holds for all non-Abelian simple groups. In this paper, we prove a modified version of Herzog’s Conjecture.