Modulation of drug (metoprolol succinate) release by inclusion of hydrophobic polymer in hydrophilic matrix

The objective of this study was to develop sustained release (SR) matrix tablets of metoprolol succinate (MS), by using different polymer combinations and fillers, to optimize by response surface methodology and to evaluate biopharmaceutical parameters of the optimized product. Matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC); and lactose and dibasic calcium phosphate dihydrate (DCP) as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was subjected to further study like scanning electron microscopy, swelling study and in vivo study in rabbit model. Both in vitro and in vivo study revealed that combining of HPMC K100M (21.95%) with EC (8.85%), and use of DCP as filler sustained the action up to 12 h. The in vivo study of new SR tablets showed significant improvement in the oral bioavailability of MS in rabbits after a single oral dose of 25 mg. The delayed T(max) and lower C(max) indicated a slow and SR of MS from the optimized matrix tablets in comparison with the immediate release dosage form. The developed SR (MS) tablet of improved efficacy can perform therapeutically better than conventional tablet.     

Powder form and stability of Pluronic mixed micelle dispersions for drug delivery applications

The aim of this work was to optimize a formulation of the Pluronic® F127/L121 mixed micelle system and evaluate it in terms of stability upon dilution in biologically relevant media and to explore the possibility of preparing F127/L121 micelles in a powder form that can be simply reconstituted to an initial freshly made mixed micelle formulation. The mixed F127/L121 micelles were prepared at a relatively high concentration of Pluronics (1% w/w for both Pluronics) using two different methods (direct dissolution and film rehydration) with an external input of energy. The optimal preparation of the mixed F127/L121 micelles (hydrodynamic diameter (d_h)?=?75?nm, polydispersity index (PDI)?=?0.287) was achieved using the film rehydration method followed by ultrasonication. Stability studies of the F127/L121 micelle system were performed at 25?°C and 37?°C and upon dilution in different biologically relevant media. The F127/L121 micelles were stable in phosphate buffered saline (PBS) upon 100-fold dilution for at least 10?d and in PBS containing bovine serum albumin upon 10 and 50-fold dilution for at least 48 and 12?h, respectively. A dry powdered form of the mixed micelles was prepared by freeze-drying after slow or fast freezing process. The influence of the type and amount of cryoprotectant on the prevention of F127/L121 micelles aggregation during the freeze-drying and reconstitution processes were evaluated. The use of trehalose (5%, w/w) and sucrose (2.5%, w/w) with slow and fast freezing process, respectively, resulted in a reconstituted product with mostly similar d_h and PDI values of the fresh micelle formulation.     

Correlation between crystal structure and morphology of potentiostatically electrodeposited silver dendritic nanostructures

Silver dendritic nanonstructures obtained by the potentiostatic electrolysis from different electrolytes at different overpotentials were characterized by the scanning electron microscopy (SEM) technique and X-ray diffraction analysis of the produced particles. The needle-like and fern-like dendrites were formed from the nitrate electrolyte at overpotentials inside and outside plateaus of the limiting diffusion current density, respectively. The three-dimensional pine-like dendrites constructed from approximately spherical grains were formed from the ammonium electrolyte at overpotentials both inside and outside plateaus of the limiting diffusion current density. The morphology of silver dendrites was correlated with their crystal structure at the semi quantiative level. The change of crystal orientation from the strong (111) preferred orientation for the needle-like dendrites to almost randomly orientied spherical grains in the pine-like dendrites obtained at the overpotential outside the plateau of the limiting diffusion current density was observed. This trend in change of crystal orientation and morphology of Ag nanostructures was accompanied by considerable increase of the specific surface area (SSA) of the produced powders. The average crystallite sizes were in the range of 38–50 nm, proving nanostructural character of the formed Ag particles.     

Verification of the Explosive Quality of TH‐5

This paper reports the characteristics of the explosive TH‐5, recycled (recovered) trinitrotoluene (TNT) with max. 5 wt‐% of hexogen (RDX). The explosive TH‐5 was obtained by delaboration of warheads and melting of explosive charges based on TNT and RDX and by separation (extraction) of high explosive components. The thermal characteristics of pure (virgin) TNT and RDX, and recycled explosive TH‐5 are determined by differential scanning calorimetry. The possibility of processing TH‐5 by pressing and casting is also examined. The comparative analysis of sensitivity of TH‐5 and TNT to friction is determined, as well as compressibility of explosives, and the detonation velocity of pressed and cast charges. Based on the analysis of experimental results, the defense standard requirements for the quality of TH‐5 are defined and possibility of practical application of explosive TH‐5 was estimated.     

Simple and Efficient Profiling of Phospholipids in Phospholipase D-modified Soy Lecithin by HPLC with Charged Aerosol Detection

Dietary phosphatidylinositol (PI) can be synthesized via phospholipase D (PLD)-catalyzed transphosphatidylation of phosphatidylcholine (PC), abundant in soy lecithin, with myo-inositol. However, a generated mixture of phospholipid (PL) classes poses a challenge for analysis. Our current work on Streptomyces PLD engineering requires a robust analytical method for profiling of PI and related PLs derived from the transphosphatidylation reactions. Therefore, we optimized an HPLC-based method with charged aerosol detector (CAD) for PL quantification. PLs were separated on a normal phase silica column by a gradient elution system using two solvents containing chloroform/methanol/1 M formic acid–triethylamine buffer in different ratios. Retention times of the PL standards and LC–MS under identical conditions were used to identity PL classes. PL standards gave linear response in 100- and 10-fold (lyso-PI) concentration range. The method provided a simple, sensitive, repeatable, and precise analysis of PI, PC, phosphatidylethanolamine, phosphatidic acid, and lyso forms of PC and PI. Compared to the similar existing method, introduction of CAD provided a three- to fivefold decrease at the lower end and a two- to fivefold increase at the upper end of the dynamic range. High precision, high sensitivity, and low limits of detection and quantification further underline the benefits of CAD in PL analysis.     

A simulation appraisal of performance of different HVAC systems in an office building

The article reports on a simulation appraisal of energy consumption, energy costs and environment impact of three systems used for space heating, and space cooling of an office building in Kragujevac, Serbia. Three investigated systems are (1) a system with a natural gas boiler and convective baseboard heaters for water space heating and window air conditioners for air space cooling; (2) a system with a natural gas boiler and individual air reheaters for air space heating and a chiller plant for air space cooling; and (3) an air-to-air heat pump for air space heating, and cooling. The systems are modeled and simulated by using EnergyPlus software. After simulations, it is found that the first investigated system has the highest energy efficiency, the best economy, and the lowest environmental impact. That is because of the fact that the first system has water as a heating medium and uses predominantly natural gas as fuel. However, in future, when for generation the grid electrical energy requires less primary energy, and becomes decarbonized, the third system would be best to conserve energy resources and environment.     

Electrodeposition of Co-Ni-MoxOy Powders: Part I. The Influence of Deposition Conditions on Powder Composition and Morphology

The Co-Ni-Mo_xO_y powders were obtained electrochemically at a constant current density from ammonia electrolyte. Ni and Co were anomalously deposited, inducing Mo deposition, which cannot be deposited separately from aqueous solutions. The obtained Co-Ni-Mo_xO_y powders were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electon microscope (SEM) methods. Based on the obtained experimental results, it was concluded that the particle size of deposited powders is influenced by the chemical composition of the electrolyte and current density imposed. XRD results suggested that obtained powders were of amorphous structure, although a Co₃Mo compound can be formed if certain experimental conditions are applied.     

Coordination via genetic learning

This paper uses genetic algorithms to model the solution to a coordination problem through learning. The coordination problem arises out of the following two stage game. At core of the two stage game is a model of social interaction in which players use visible goods as signals about the identity of other players. If these signals are informative enough, players use them to condition their social interaction. Importantly, accurate signals are mutually beneficial. This game is then wrapped in another in which players choose their visible goods. There are many types of players and many visible goods that could be used to signal type. There are many equilibria of the two stage game, some of which allow individuals to perfectly signal their type in all social interactions, and others of which do not. The perfect signaling equilibria Pareto dominate the others, but since there are many of them, the players face a difficult coordination problem. We approach this coordination problem using genetic algorithms to simulate learning in this game. A player is a genetic code that evolves via selection.Questions of primary interest concern the set of parameter values such that the players manage to solve the coordination problem. The results of simulations indicate that the convergence of the genetic algorithm to a perfect signaling equilibrium depends on the values of the parameters that determine players' payoffs.We analyze two different scenarios. In one scenario, each player makes one (unconditional) decision to either use the visible goods displayed by other players as type signals, or to ignore the visible goods they display. In the other scenario, the decision to regard a player's visible good as a type signal is conditional on the good displayed. Our results indicate that it is easier for players to solve the coordination problem under the second scenario.     

Removal of Natural Organic Matter from Groundwater Using Advanced Oxidation Processes at a Pilot Scale Drinking Water Treatment Plant in the Central Banat Region (Serbia)

To improve water quality, a pilot-scale evaluation into upgrading the conventional treatment process was conducted. By following DOC content, UV₂₅₄ absorbance, SUVA and by-products formation, three oxidative pre-treatments were evaluated: pre-ozonation (2.2 g O₃/m³); O₃/H₂O₂ process (2.2 g O₃/m³; H₂O₂:O₃ = 1:2) and O₃/H₂O₂ process (2.2 g O₃/m³; H₂O₂:O₃ = 2:1). The second pre-treatment gave the best results, with a final average DOC content of 0.9 mg C/L, UV₂₅₄ absorbance of 0.06 cm^?1 and the lowest THMFP of 130 μg/L. UV₂₅₄ absorbance can serve as a proper indicator for predicting THM and HAA formation, yielding a correlation coefficient ≥ 0.90.     

Modeling of petroleum products sampling processes

Abstract

This paper describes a holistic approach to operation processes in the domain of petroleum products sampling which is important in validating the performance of custody transfer measurements. The acquisition and process visualization is followed by a detailed analysis of all relevant processes and discussion. In that way, the most important aspects related to sampling, which comply with the most rigorous requirements for custody transfer, will be shown. In order to represent petroleum products sampling, a model has been defined and connected to the defined processes in a BPMN 2.0 notation. Thereafter, the notation was enriched with new elements, representing other complex segments, such as defining selection criteria, sampling handling and operational considerations. In that regard, different situations and factors were integrated and enriched with new details, enabling guidance for the correct selection and smooth running of a sampling system.