A Mechanistic Investigation of an Amorphous Pharmaceutical and Its Solid Dispersions, Part I: A Comparative Analysis by Thermally Stimulated Depolarization Current and Differential Scanning Calorimetry

2004 ◽  
Vol 21 (11) ◽  
pp. 2025-2030 ◽  
Author(s):  
Rama A. Shmeis ◽  
Zeren Wang ◽  
Steven L. Krill
2021 ◽  
pp. 50-53
Author(s):  
Варужан Амбарцумович Саркисян ◽  
Юлия Владимировна Фролова ◽  
Роман Владимирович Соболев ◽  
Алла Алексеевна Кочеткова

Полисахариды являются многофункциональными пищевыми ингредиентами, применяемыми в различных типах пищевых продуктов. Особый интерес вызывает изучение роли полисахаридов в качестве потенциальных про- или антиоксидантов в составе пищевых эмульсий. Основным недостатком традиционных способов оценки развития окислительных процессов в эмульсиях является необходимость предварительной экстракции жировой фазы, что может сопровождаться искажением реальных значений показателей окисления. В данной работе влияние полисахаридов на окислительную стабильность эмульсий изучено при помощи реактора окислительной устойчивости Oxitest, который позволяет проводить прямое измерение потребления кислорода в процессе окисления липидов, тем самым исключая необходимость экстракции и повышая достоверность полученных данных. Проведен сравнительный анализ 6 различных полисахаридов (альгинат натрия, i-каррагинан, камедь рожкового дерева, пектин амидированный, пектин высокоэтерифицированный, картофельный крахмал) в составе пищевых эмульсий. Методами ИК-Фурье спектроскопии и дифференциально-сканирующей калориметрии охарактеризованы состав и свойства исходных полисахаридов. Изучена вязкость 0,5%-ных растворов полисахаридов при помощи метода ротационной вискозиметрии. В результате проведенного анализа полисахаридов выявлены и охарактеризованы основные отличия в колебательных спектрах поглощения функциональных групп. Методом дифференциально-сканирующей калориметрии определены энтальпии теплового эффекта отделения влаги и начала термической деградации полисахаридов. Проведен многомерный статистический анализ полученных данных, выявивший основные закономерности между структурой и свойствами полисахаридов в составе эмульсий. Наибольшую окислительную стабильность проявили эмульсии на основе камеди рожкового дерева и амидированного пектина. Polysaccharides are multifunctional food ingredients used in various types of food products. The role of polysaccharides as potential pro- or antioxidants in food emulsions is of particular interest is. The main drawback of traditional methods for assessing the development of oxidative processes in emulsions is the need for preliminary extraction of the fat phase, which may be accompanied by a distortion of the real values of oxidation indices. In this work, the effect of polysaccharides on the oxidative stability of emulsions was studied using the Oxitest oxidative stability reactor, which allows the direct measurement of oxygen consumption during lipid oxidation, thereby eliminating the need for extraction and increasing the reliability of the obtained data. Comparative analysis of 6 different polysaccharides (sodium alginate, i-carrageenan, locust bean gum, amidated pectin, highly esterified pectin, potato starch) in food emulsions was performed. The composition and properties of the initial polysaccharides were characterized by FTIR spectroscopy and differential scanning calorimetry methods. The viscosity of 0.5% solutions of polysaccharides was studied using the rotary viscometry method. The analysis of polysaccharides revealed and characterized the main differences in the vibrational absorption spectra of functional groups. The enthalpies of the thermal effect of moisture separation and the beginning of thermal degradation of polysaccharides were determined by differential scanning calorimetry. A multivariate statistical analysis of the obtained data revealed the main relations between the structure and properties of polysaccharides in emulsions. Emulsions based on locust bean gum and amidized pectin exhibited the highest oxidative stability.


2011 ◽  
Vol 493-494 ◽  
pp. 170-174
Author(s):  
Rumi Hiratai ◽  
Miho Nakamura ◽  
Akiko Nagai ◽  
Kimihiro Yamashita

We have shown that hydroxyapatite (HA), which characteristics were similar to those of bone’s inorganic components, had polarization capability and was possible to accumulate electricity under high temperature and pressure. Then, we presumed that bones had polarization capability which enabled electrical storage and conducted the experiment to measure the polarization capability of bones using rabbit’s femurs. After preparing and polarizing bone samples using KOH treatment (koh), KOH and baking treatment (koh+bake) and decalcification treatment (decalcification) as well as the bone without any treatment (untreat), quantitative amounts of stored charge in samples were determined by thermally stimulated depolarization current (TSDC) measurement of these samples. Under the condition of 400 °C for 1 h with the electric fields of 5kV/cm, samples of koh, koh+bake, and untreat showed polarization capability. In addition, under the polarization condition of 37 °C for 1 hour with the electric fields of 5kV/cm, all samples showed polarization capability. Those findings can be summarized that bones have the polarization capability which enables electrical storage and polarization of bones is possible even under the low temperature condition, which was at 37 °C in our experiment, where polarization is impossible for HA.


2006 ◽  
Vol 309-311 ◽  
pp. 333-336
Author(s):  
Emiko Amaoka ◽  
Erik Vedel ◽  
Satoshi Nakamura ◽  
Yusuke Moriyoshi ◽  
Jukka I. Salonen ◽  
...  

We investigated the electrical polarizability of MgO and B2O3 containing bioactive glass (MBG). The MBG material with good manufacturing properties but low bioactivity was electrically polarized at a high dc field. The electrical polarizability of MBG was evaluated by thermally stimulated depolarization current (TSDC) measurements and immersion in simulated body fluid (SBF). The early precipitation of calcium phosphate on the negatively charged surface of the treated MBG demonstrated the increased bioactivity of the material and confirmed its polarizability. It is suggested that the electrical interactions between the polarized MBG and ions in SBF promoted the formation of the calcium phosphate precipitation. Accordingly, the increased bioactivity of the MBG in SBF is suggested to demonstrate the conversion of MBG into electrovector ceramics by the polarization treatment.


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