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Abstract

In the present study we have determined some characteristics (aspect, odor, solubility, emulsion type, water and volatile substances content, total fatty matter, saponification index, ester index) for three pharmaceutical ointments belonging to the group of non-steroidal anti-inflammatory: Diclac, Ketonal, Indometacin and one antibiotic ointment for ophthalmic use: Ophtagram. In order to achieve stability study of studied ointments, the pH, the acidity index, the peroxide index and the iodine index were determined over a year every three months. After 9 months from the opening of the tubes, analytical determinations have shown that pH values, acidity, peroxide and iodine indexes no longer fit to the values recommended for medical use, which confirms the directions available on the package.

Stability Studies of Torque Transducers

The present paper discusses the stability studies carried out on a small number of torque transducers over the years with capacities ranging from 10 Nm to 1000 Nm. The torque transducers have been calibrated using the torque standard machine based on the written standard calibration procedure. The study reveals that the uncertainty of measurement of torque transducers has been varying appreciably and it is more for lower range. Besides, the deviation from their average values has also been studied and found to be varying through the years.

Abstract

The aim of this work is the study of stability and kinetics of hydrolysis of the chosen compounds, derivatives of 2-hydroxy-3-[2-(4-methoxyphenyl)ethylamino]propyl-4- [(alkoxycarbonyl)amino]benzoates and 2-hydroxy-3-[2-(2-methoxyphenyl)ethylamino] propyl-4-[(alkoxycarbonyl)amino]benzoates with potential ultra-short beta-adrenolytic activity. The studied compounds are different in the position of the substituent on the benzene ring in the side chain as well as in the aromatic ring in position 4 with alkyl- (methyl- to butyl-) carbamate. Thin layer chromatography and UV-area spectrophotometry are used in order to establish the stability of these potential pharmaceuticals. The stability studies of the compounds were examined in acidic and alkaline media, in buffers and due oxidation at room and at elevated temperature chromatographically, and Rf values of incipient products and degradation products were detected. Kinetics of acid and base hydrolysis in various solutions at temperatures 80 °C and 100 °C were examined through UV-area spectrophotometry. Kinetic parameters such as rate constant k, half-life period t1/2 and usable life t90 were determined.

References [1] Bučiova, L., Borovansky, A., Čižmarik, J., Csollei, J., Švec, P., Kozlovsky, J., Račanska, E., Beneš, L.: Study of influences of changes in the connecting chain on biological activity in group of basic phenylcarbamates (in Slovak). Čes slov Farm 1987;36:339-344. [2] Čižmarik, J., Borovansky, A., Švec, P.: Study of local anesthetics. LII. Piperidinoethyl esters of alkoxyphenylcarbamuic acids. Acta Fac Pharm Univ Comenianae 1976;29:53-80. [3] Eriksen, S. P., Stelmach, H.: Single-step stability studies. J Pharm Sci 1965;54:1029-1034. [4] Ficara, R

Stability studies of chitosan-DNA-FAP-B nanoparticles for gene delivery to lung epithelial cells

A successful gene delivery system requires efficiency and stability during storage. Stability studies are imperative for nanomedicines containing biotechnological products such as plasmids and targeting peptides. Chitosan-DNA-FAP-B nanoparticles are novel non-viral vectors for specific gene delivery to the lung epithelial cells. In this study, the storage stability of chitosan-DNA-FAP-B nanoparticles at -20, 5 and 24 °C was examined. Size, zeta potential and transfection efficiency of these nano-particles in storage were also evaluated. Stability studies showed that chitosan-DNA-FAP-B nanoparticles were stable after 1 month when stored at -20 °C and retained their initial size, zeta potential and transfection efficiency. However, their stability was not desirable at 5 and 24 °C. Based on these results, it can be concluded that chitosan-DNA-FAP-B nanoparticles can be a promising candidate for gene delivery to lung epithelial cells with good storage stability at -20 °C during 1 month.

Abstract

This paper deals with the stability study of the nonlinear Saint-Venant Partial Differential Equation (PDE). The proposed approach is based on the multi-model concept which takes into account some Linear Time Invariant (LTI) models defined around a set of operating points. This method allows describing the dynamics of this nonlinear system in an infinite dimensional space over a wide operating range. A stability analysis of the nonlinear Saint-Venant PDE is proposed both by using Linear Matrix Inequalities (LMIs) and an Internal Model Boundary Control (IMBC) structure. The method is applied both in simulations and real experiments through a microchannel, illustrating thus the theoretical results developed in the paper.

. Hatziargyriou, D. Hill, A. Stankovic, C. Taylor, T. Van Cutsm, and V. Vittal, “Definition Classification of Power System Stability”, IEEE Transactions on Power System , vol. 19, no. 3, pp. 1387–1401, 2004. [4] S. E. M. de Oliveira and J. F. de Queiroz, “Modal Dynamic Equivalent for Electric Power Systems. I. Theory”, IEEE Transactions on Power System , vol. 3, no. 4, pp. 1723–1730, 1988. [5] L. Wang, M. Klein, S. Yrga, and P. Kundur, “Dynamic Reduction of Large Power Systems for Stability Studies”, IEEE Transactions on Power Systems , vol. 12, no. 2, pp. 889–895, 1997. [6

Abstract

Neural networks are used as triggers at highenergy physics detectors. These triggers can separate the event that must be saved for later analysis from the other events or noises. Using the raw data of the detector, the signal and the background can be separated offline. After separation, sets of signals and backgrounds can be used to train the neural network. A gas-filled detector (multiwire proportional chamber) was used to study the trigger at different noise levels to find the most stable neural network that tolerates the random hits. The ratio of the recognized and the unrecognized signal and background events is used for the measurement. Its stability is part of the systematical uncertainty.

Influence of some commercially available types of microcrystalline cellulose (MCC) on the stability of certain active pharmaceutical ingredients (APIs), when in contact, has been investigated. Two structurally similar APIs, perindopril erbumine (PER) and enalapril maleate (EM), both well-known angiotensin-converting enzyme inhibitors were used. The main properties of an MCC that could determine the stability for each API were measured and correlated to the stability of these two APIs in binary mixtures. The stability of these APIs differed when in contact with different types of MCC. The dominant properties of MCC from one manufacturer were surface features that influenced the stability of PER and acidity that influenced the stability of EM. In the case of MCC from other manufacturers, unbound water was stability determining for both substances.

Abstract

In this paper we present the results of measured physical parameters of self-organized structures consisting of hydrophobic functionalized silver nanoparticles and amphiphilic molecules capable of micelles formation. Those systems may be considered as simple models for transfer of nanoparticles through the biological membrane. Three different surfactants were used: negatively charged sodium dodecyl sulphite, SDS, neutral Triton X-100 and positively charged tetredodecyltrimethyl ammonium bromide, TTABr. We have found that hydrophobic functionalized Ag nanoparticles are encapsulated in neutral Triton X-100 micelles with a diameter of 10 nm without significant change in the size of the micelles. The efficiency of encapsulation of Ag by SDS micelles is lower compared to Triron X-100 and no incorporation of Ag nanoparticles into TTABr occurs. Obtained results indicate that in aqueous environment ionic properties of molecules creating micelles and concentration ratios between components determine the efficiency and kinetics of two competitive processes association or aggregation of nanoparticles and encapsulation of Ag nanoparticles within micelles.