Search results for "chemical stability"
showing 6 items of 96 documents
3PC-030 Physical, chemical and microbiological stability of sirolimus 0.4% in topical formulations
2019
Background Facial angiofibromas in tuberous sclerosis are an aesthetic problem within the clinical context of the disease. There are currently few stability studies that allow selecting the best topical sirolimus therapy. Purpose To improve the formulation of sirolimus 0.4% for the treatment of facial angiofibromas in tuberous sclerosis and to determine the period of validity (physical, chemical and microbiological stability) of the proposed formulations. Material and methods Three formulations of sirolimus 0.4% were prepared (each in duplicate, A and B). Facilities and equipment: biological safety cabinet with individual protection equipment for the manipulator. Conditions: aluminum tubes,…
Sequential dissociation of insulin amyloids probed by high pressure Fourier transform infrared spectroscopy
2012
High Pressure (HP) Fourier Transform Infrared Spectroscopy (FTIR) has been here employed to investigate the thermodynamic stability of bovine pancreatic insulin (BPI) amyloids. Once the aggregation reaction has started, the backbone arrangement of the proteins forming the amyloid is known to reach a stationary phase in few hours; after this time the infrared absorption of fibrils becomes stable. It is here shown how the further stabilization of the structure during the stationary phase can be probed via FTIR spectroscopy, through the observation of the high pressure behaviour of fibrils formed at different maturation stages. We report on the high pressure fragmentation of insulin amyloids, …
Interaction of methyltin(IV) compounds with carboxylate ligands. Part 1: formation and stability of methyltin(IV)–carboxylate complexes and their rel…
2006
Quantitative data on the stability of mono-, di- and trimethyltin(IV)-carboxylate complexes (acetate, malonate, succinate, malate, oxydiacetate, diethylenetrioxydiacetate, tricarballylate, citrate, butanetetracarboxylate and mellitate) are reported at t=25°C and I → 0 mol l - 1 . Several mononuclear, mixed proton, mixed hydroxo and polynuclear species are formed in these systems. As expected, the stability trend is mono- > di- > trimethyltin(IV) and mono < di < tri < tetra < hexa for the organotin moieties and carboxylate ligands investigated, respectively. Moreover, ligands containing, in addition to carboxylic,-O-and-OH groups show a significantly higher stability with respect to analogou…
Assessment of Physical and Chemical Stability of Different Magnesium Compounds in Tablets
2020
Modern lifestyle, excessive chemicalization of agricultural products, excessive processing and refining of food, cause a decrease in daily intake of magnesium, cation with an extremely important role in prevention and treatment of many diseases. As a result, there arises the need for extra magnesium intake in the form of dietary supplements. In this study were evaluated the physical and chemical stability of magnesium-containing tablets, depending on the active compound and the excipients used. Magnesium tablets in the form of orotate, lactate, citrate, oxide and hydroxide were taken into study and physical and chemical stability were observed over the validity period, at 6 and at 12 month…
Application of the PHREEQC Program to Assess the Chemical Stability of Tap Water in Kielce
2020
Badania przeprowadzono na próbkach wody w Kielcach pochodzące z dwóch ujęć: Białogon i Zagnańsk. Przedstawiono wyniki wybranych wskaźników dla tych wód, m.in. najważniejszych wpływających na ich stabilność chemiczną, tj. wapnia lub magnezu. Następnie, za pomocą programu PHREEQC, obliczono wskaźniki stabilności dla wód w Kielcach z dwóch ujęć, o których mowa. W kolejnym etapie sprawdzono poprawność metody badania wody za pomocą programu poprzez bilans jonowy wody i porównanie pH wyznaczonej wody z wartością wyznaczoną w wyniku obliczeń. Dla wyżej wymienionych czynności przygotowano tabele i obliczenia, na podstawie których wyciągnięto odpowiednie wnioski
Crystal structure and Hirshfeld surface analysis of [N(CH3)4][2,2′-Fe(1,7-closo-C2B9H11)2]
2017
Abstract This work investigates the meta -ferrabis(dicarbollide) anion that was isolated as salt of tetramethylammonium. The structure of the obtained crystal consisted of discrete [2,2′-Fe(1,7- closo -C 2 B 9 H 11 ) 2 ] − anions and disordered [N(CH 3 ) 4 ] + cations. The anion had a considerable chemical stability ensured by ionic and Van der Waals interactions. Thus, Hirshfeld surfaces and fingerprint plot were used to visualize, explore, and quantify intermolecular interactions in the crystal lattice of the title compound. This investigation proved that close contacts were dominated by H⋯H interactions.