scholarly journals Stability Study of an Electrothermally-Actuated MEMS Mirror with Al/SiO2 Bimorphs

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 693 ◽  
Author(s):  
Peng Wang ◽  
YaBing Liu ◽  
Donglin Wang ◽  
Huan Liu ◽  
Weiguo Liu ◽  
...  
Keyword(s):  
Fill Factor ◽  
Microelectromechanical Systems ◽  
Stability Study ◽  
Driving Voltage ◽  
Electrothermal Actuation ◽  
Different Temperatures ◽  
Dynamic Scan ◽  
Bimorph Actuators ◽  
The Stability

Electrothermal actuation is one of the main actuation mechanisms and has been employed to make scanning microelectromechanical systems (MEMS) mirrors with large scan range, high fill factor, and low driving voltage, but there exist long-term drifting issues in electrothermal bimorph actuators whose causes are not well understood. In this paper, the stability of an Al / SiO 2 bimorph electrothermal MEMS mirror operated in both static and dynamic scan mode has been studied. Particularly, the angular drifts of the MEMS mirror plate were measured over 90 h at different temperatures in the range of 50 – 150 °C. The experiments show that the temporal drift of the mirror plate orientation largely depends on the temperature of the electrothermal bimorph actuators. Interestingly, it is found that the angular drift changes from falling to rising as the temperature increases. An optimal operating temperature between 75 °C to 100 °C for the MEMS mirror is identified. At this temperature, the MEMS mirror exhibited stable scanning with an angular drift of less than 0.0001 °/h.

scholarly journals Limitations and Challenges in the Stability of Cysteamine Eye Drop Compounded Formulations

2021 ◽  
Vol 15 (1) ◽  
pp. 2
Author(s):  
Cristina Martín-Sabroso ◽  
Mario Alonso-González ◽  
Ana Fernández-Carballido ◽  
Juan Aparicio-Blanco ◽  
Damián Córdoba-Díaz ◽  
...  
Keyword(s):  
Shelf Life ◽  
Stability Study ◽  
Eye Drops ◽  
Microbiological Analysis ◽  
Nitrogen Gas ◽  
Long Term Stability ◽  
Main Degradation Product ◽  
The Stability ◽  
Unstable Molecule

Accumulation of cystine crystals in the cornea of patients suffering from cystinosis is considered pathognomonic and can lead to severe ocular complications. Cysteamine eye drop compounded formulations, commonly prepared by hospital pharmacy services, are meant to diminish the build-up of corneal cystine crystals. The objective of this work was to analyze whether the shelf life proposed for six formulations prepared following different protocols used in hospital pharmacies is adequate to guarantee the quality and efficacy of cysteamine eye drops. The long-term and in-use stabilities of these preparations were studied using different parameters: content of cysteamine and its main degradation product cystamine; appearance, color and odor; pH and viscosity; and microbiological analysis. The results obtained show that degradation of cysteamine was between 20% and 50% after one month of storage in the long-term stability study and between 35% and 60% in the in-use study. These data confirm that cysteamine is a very unstable molecule in aqueous solution, the presence of oxygen being the main degradation factor. Saturation with nitrogen gas of the solutions offers a means of reducing cysteamine degradation. Overall, all the formulae studied presented high instability at the end of their shelf life, suggesting that their clinical efficacy might be dramatically compromised.

scholarly journals STABILITY STUDY OF AMLODIPINE BESYLATE AND BISOPROLOL FUMARATE IN AQUEOUS SOLUTIONS

2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Irena Kasagić Vujanović ◽  
Dijana Jelić ◽  
Vesna Antunović ◽  
Biljana Jančić Stojanović ◽  
Darko Ivanović
Keyword(s):  
Relevant Information ◽  
Pharmaceutical Product ◽  
Stability Study ◽  
Amlodipine Besylate ◽  
Time Intervals ◽  
Constant Rate ◽  
Different Temperatures ◽  
The Media ◽  
Two Temperatures ◽  
The Stability

Valuable information concerning stability of compounds can be obtained by using different media (water, hydrochloric acid or sodium hydroxide) for dissolution of active pharmaceutical substances. Furthermore, additional knowledge is gained by performing experiments at different temperatures. This research paper deals with the stability of amlodipine besylate and bisoprolol fumarate in different media at different temperatures, whereby certain conclusions are drawn. For stability assessment, chemical kinetics approach was used, and constant rate (k), half-time (t1/2) and activation energy (Ea) were used for prediction of compound stability degree. The stability of amlodipine besylate and bisoprolol fumarate were tested, both separately and in mixture, in water and in 0.01M HCl. All the investigated solutions were treated at two temperatures 25° and 70°C at the following time intervals: 0, 1 h, 24 h, 48 h and 72 h. Hydrophilic Interaction Liquid Chromatography – HILIC method, previously developed and validated, was used. On the basis of obtained results it was concluded that amlodipine-besylate was more stable in water than in acid medium, more stable in mixture rather than individually and more stable at lower temperatures. This was confirmed by the obtained values of monitored parameters: amlodipine besylate Ea = 30.68 kJ mol-1, k (25 °C) = 0.000333 mM h-1, k (70 °C) = 0.00169 mM h-1; amlodipine besylate in mixture Ea = 42,414 kJ mol-1, k (25 °C) = 1.27∙10-4 mM h-1, k (70 °C) = 0.0012 mM h-1. Based on the obtained approximate Ea value for bisoprolol fumarate in acid (59 kJ mol-1) and in water (56 kJ mol-1), bisoprolol fumarate showed excellent stability against the media in which it was studied. On the other hand, the temperature had a significant effect on the stability of bisoprolol fumarate. These results provide the relevant information about the stability of the tested active substances, and may be of importance during the development of an appropriate pharmaceutical product. A bigger influence on the stability of bisoprolol fumarate had a temperature effect.

One-Year Stability of the Devereux Early Childhood Assessment for Preschoolers, Second Edition

2017 ◽  
Vol 36 (8) ◽  
pp. 829-834
Author(s):  
John S. Carlson ◽  
Dylan S. T. Voris
Keyword(s):  
Early Childhood ◽  
Rating Scales ◽  
Progress Monitoring ◽  
Stability Study ◽  
Early Childhood Assessment ◽  
Parent Rating ◽  
Devereux Early Childhood Assessment ◽  
One Year ◽  
The Stability

The Devereux Early Childhood Assessment (DECA) and recently updated Devereux Early Childhood Assessment for Preschoolers, Second Edition (DECA-P2) are strength-based measures that can inform early intervention. Whereas the short-term psychometric properties of these parent rating scales are strong, little is known about their long-term stability. Study findings from a diverse Head Start sample ( N = 282, DECA; N = 346, DECA-P2) revealed 12-month, test–retest reliability of protective factors ( r = .65) to be equivalent on the DECA-P2 and the DECA. The stability of parent ratings of behavior concerns appears improved in the newer edition ( r = .53 vs. r = .46). Additional consideration should be given to the stability of the DECA-P2 and its use as short- and long-term social, emotional, and behavioral intervention progress monitoring tool.

The Stability Study of Thermodynamic Parameters of Sorption of Light Hydrocarbons on Poly [Trimethylsilyl (Propyn-1)] at Different Temperatures

2019 ◽  
Vol 57 (9) ◽  
pp. 778-783
Author(s):  
V E Shiryaeva ◽  
A A Korolev ◽  
T P Popova ◽  
A Y Kanateva ◽  
A A Kurganov
Keyword(s):  
Stationary Phase ◽  
Thermodynamic Parameters ◽  
Heating Temperature ◽  
Chromatographic Determination ◽  
Stability Study ◽  
Light Hydrocarbons ◽  
Different Temperatures ◽  
Entropy Factor ◽  
The Stability

Abstract Chromatographic determination of the thermodynamic parameters of sorption for light hydrocarbons retention on a stationary phase based on poly [trimethylsilyl (propyn-1)] (PTMSP) was performed and the effect of column preheating at temperatures up to 260°C on the retention of analytes was investigated. It was shown that heating the column to 130°C does not affect the retention of the analytes. At temperatures above 130°C, the gradual decrease of the retention of analytes on PTMSP stationary phase is observed. The process is non-selective and proceeds at the same extent for all the studied hydrocarbons, regardless of the size and geometry of the molecule. Values of enthalpy and entropy of sorption of light hydrocarbons are determined for the original column and after its aging at 200°C. The enthalpy of sorption of the analytes at the PTMSP phase is practically independent on the heating temperature of the PTMSP phase, whereas the loss of entropy increases after heating. The increase of the entropy factor after the heating of the PTMSP stationary phase is associated with its aging and is confirmed by the construction of compensation functions for treated and untreated columns.

scholarly journals New β-Carotene-Chitooligosaccharides Complexes for Food Fortification: Stability Study

Foods ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 765 ◽  
Author(s):  
Alma Bockuviene ◽  
Jolanta Sereikaite
Keyword(s):  
Freeze Drying ◽  
Stability Study ◽  
Food Fortification ◽  
Kinetics Parameters ◽  
Long Term Stability ◽  
First Order Kinetics ◽  
The Stability ◽  
Β Carotene ◽  
Carotene Degradation

The application of β-carotene in food industry is limited due to its chemical instability. The drawback may be overcome by designing new delivery systems. The stability of β-carotene complexed with chitooligosaccharides by kneading, freeze-drying and sonication methods was investigated under various conditions. The first-order kinetics parameters of the reaction of β-carotene degradation were calculated. The complexation improved the stability of β-carotene at high temperatures and ensured its long-term stability in the dark at 4 °C and 24 °C, and in the light at 24 °C. In water solutions, the best characteristics were exhibited by the complexes prepared by freeze-drying and sonication methods. In the powder form, the complexes retained their colour for the period of the investigation of four months. The calculated total colour differences of the complexes were qualified as appreciable, detectable by ordinary people, but not large. Therefore, β-carotene-chitooligosaccharides complexes could be used as a new delivery system suitable for food fortification.

scholarly journals DEVELOPMENT OF NANOEMULSION CONTAINING PELARGONIUM GRAVEOLENS OIL: CHARACTERIZATION AND STABILITY STUDY

2016 ◽  
Vol 8 (12) ◽  
pp. 271 ◽  
Author(s):  
Janice Luehring Giongo ◽  
Rodrigo De Almeida Vaucher ◽  
Aline Ourique ◽  
MÍriam Steffler ◽  
Clarissa Piccinin Frizzo ◽  
...  
Keyword(s):  
Particle Size ◽  
Storage Temperature ◽  
Thermo Gravimetric Analysis ◽  
Physicochemical Characteristics ◽  
Stability Study ◽  
Gas Chromatography Mass Spectrometry ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
The Stability

<p><strong>Objective: </strong>To develop, characterize and evaluate the stability of nanoemulsions containing geranium oil (NEG) at different temperatures (4 °C, 25 °C and 45 °C) for 90 d.</p><p><strong>Methods: </strong>The quantification of oil in the nanostructure was performed by <a href="https://www.google.com.br/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=1&amp;cad=rja&amp;uact=8&amp;ved=0ahUKEwiYjL3Niv7OAhVJI5AKHZ-_AeUQFggfMAA&amp;url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FGas_chromatography%25E2%2580%2593mass_spectrometry&amp;usg=AFQjCNE3N9EyqMTXtw7u0lxolSlnU5zJfQ">gas chromatography–mass spectrometry</a> (GC-MS). The NEG was prepared in Ultra-Turrex and characterized by determining the particle size, polydispersity indices and pH. The thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) to evaluate the thermal stability of the compounds, the thermal events and morphological analyses of NEG, respectively.<strong></strong></p><p><strong>Results: </strong>The results allow us to suggest that the use the ultra-turrax method is a strategy good to NEG preparation. The stability of the NEG was strongly influenced by storage temperature, with droplet size increasing rapidly at higher temperatures (45 °C), which was attributed to coalescence near the phase inversion temperature. The NEG submitted the low temperatures (4±2 °C) remained with the same particle size value (164 nm). However, the citronellol and geraniol showed a significant reduction throughout the test even in these conditions of temperature. Thermogram of NEG shows the crystallization peak at the cooling cycle in-20.1 °C and a melting was observed at 1.5 °C. TEM images indicated that NEG was spherical and nanometric.</p><p><strong>Conclusion: </strong>The proposed Ultra-Turrax method is simple which prevents volatilization of GO for the production of NEG. The formulations presented good physicochemical characteristics and stability for 90 d was only achieved in 4 °C.</p>

Stability Study of Epirubicin in Nacl 0.9% Injection

1997 ◽  
Vol 31 (9) ◽  
pp. 992-995 ◽  
Author(s):  
Montserrat Pujol ◽  
Montserrat Muñoz ◽  
Josefina Prat ◽  
Victoria Girona ◽  
Jordi De Bolós
Keyword(s):  
Shelf Life ◽  
Room Temperature ◽  
Degradation Kinetics ◽  
Storage Conditions ◽  
Hplc Method ◽  
Stability Study ◽  
Chemistry Laboratory ◽  
Maximum Decrease ◽  
Different Temperatures ◽  
The Stability

Objective To determine the stability of epirubicin in NaCl 0.9% injection under hospital storage conditions. Methods NaCl 0.9% solution was added to epirubicin iyophilized powder to make a final concentration of 1 mg/mL to study the degradation kinetics and 2 mg/mL to study the stability in polypropylene syringes under hospital conditions. Setting Physical chemistry laboratory, Unitat de Fisicoquímica, Universitat de Barcelona. Main outcome Measures Solutions of epirubicin at 2 mg/mL in NaCl 0.9% solutions stored in plastic syringes were studied under hospital conditions at room temperature (25 ± 1 °C) and under refrigeration (4 ± 1 °C) both protected from light and exposed to room light (~50 lumens/m2). All samples were studied in triplicate and epirubicin concentrations were obtained periodically throughout each storage/time condition via a specific stability-indicating HPLC method. To determine the degradation kinetics, solutions of epirubicin in NaCl 0.9% at 1 mg/mL were stored at different temperatures (40, 50, and 60 °C) to obtain the rate degradation constant and the shelf life at room temperature and under refrigeration. Results The degradation of epirubicin in NaCl 0.9% solutions follows first-order kinetics. The shelf life was defined as the time by which the epirubicin concentration had decreased by 10% from the initial concentration. In this study, epirubicin was stable in NaCl 0.9% injection stored in polypropylene containers for all time periods and all conditions. That results in a shelf life of at least 14 and 180 days at 25 and 4 °C, respectively. The maximum decrease in epirubicin concentration observed at 25 °C and 14 days was 4%, and at 4 °C and 180 days was 8%. The predicted shelf life obtained from the Arrhenius equation was 72.9 ± 0.2 and 3070 ± 15 days at 25 and 4 °C, respectively, in both dark and illuminated conditions. Conclusions Solutions of epirubicin in NaCl 0.9% at 2 mg/mL are chemically stable when they are stored in polypropylene syringes under hospital storage conditions. No special precaution is neccessary to protect epirubicin solutions (2 mg/mL) from light.

scholarly journals Bio-analytical Approach for Stability Studies of Bendroflumethiazide Materials

2021 ◽  
pp. 195-203
Author(s):  
B. Veeraswami ◽  
V. M. K. Naveen
Keyword(s):  
Stability Study ◽  
Stability Studies ◽  
Dry Extract ◽  
Long Term Stability ◽  
Analytical Stability ◽  
Ich Guidelines ◽  
The Stability ◽  
Efficacy Prediction

In this paper a comprehensive study of stability related, and evidence based best practices of Bio-analytical stability on Bendroflumethiazide drug samples are studied. The proposed approach is very significant and essential for the drugs development process address the specify the acceptancy, purity, efficacy, prediction of strength and quality of the drugs. The stability study constituents several methods like Bench-Top, Auto-sampler, Freeze-Thaw, Dry-extract, Wet-extract, Short-term, long-Term stability studies at relative intervals results the complete stability information about the drug under the proposed and validated method. There ported out comes of this methos shows this drug have good stability according to ICH guidelines.

scholarly journals Development of methods for analysis of the amount of flavonoids and their stability study in the combined dental gel

2021 ◽  
pp. 3-10
Author(s):  
Yu. Maslii ◽  
A. Materiienko ◽  
O. Ruban ◽  
I. Bezruk ◽  
L. Ivanauskas
Keyword(s):  
Stability Study ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Plant Origin ◽  
Active Components ◽  
Drug Substances ◽  
The Stability ◽  
And Storage ◽  
Active Substances

An important aspect in the pharmaceutical development of dental medicines is to provide them with a prolonged therapeutic effect while reducing the side effects of drug substances and the possibility of long-term use. This can be achieved by using active components of plant origin. Aim. To develop methods for analyzing biologically active substances in the composition of a new combined dental gel. Materials and methods. The study object was a dental gel containing “Phytodent” complex tincture (PJSC “CPP Chervona zirka”, Ukraine). Based on the analysis of the composition of the tincture it was proposed to carry out standardization by the amount of biologically active substances, namely flavonoids. Identification was carried out by TLC, while the quantitative determination by absorption spectrophotometry, the ultraviolet and visible method by the reaction with aluminum chloride using the standard method calculated with reference to rutin and the absorbance measurement at 406 nm. Results and discussion. As a result of the research, the methods for the analysis of flavonoids in the composition of the new combined gel have been developed. The spectrophotometric method developed is characterized by specificity, accuracy, precision and linearity with r = 0.9998. One of the important issues when using components of plant origin is their stability both during preparation and storage. Using the method developed the stability of flavonoids has been studied depending on pH changes of the carbomer-based dental gel. Conclusions. It has been determined that the methods developed are easily reproducible and allow to identifying and quantifying flavonoids in the dental gel. It has been found that a stable content of flavonoids is characteristic of the carbomer-based gel neutralized to pH values from 5.0 to 6.0.

scholarly journals Effect of the buffer system on stability of tetracaine hydrochloride 0.5% eyedrops

2001 ◽  
Vol 47 ◽  
pp. 15-20
Author(s):  
Emilija Fredro-Kumbaradzi ◽  
Tanja Milenkoska ◽  
Marija Glavas-Dodov ◽  
Katerina Goracinova ◽  
Kristina Mladenovska
Keyword(s):  
Degradation Rate ◽  
Ph Value ◽  
Degradation Products ◽  
Borate Buffer ◽  
Buffer System ◽  
Constant Ph ◽  
Accelerated Stability ◽  
Different Temperatures ◽  
The Stability

The effect of the buffer system on the stability of tetracaine hydrochloride in eyedrop formulation was evaluated. Eyedrop formulations containing tetracaine hydrochloride 0.5%(w/v) were prepared using different buffer systems (acetate, phosphate and borate buffer) under a constant pH of 5.4, and a buffer concentration of 0.06M. Long-term tests at 26 o C and accelerated stability tests at elevated temperature (45, 50, 60 o C) over a period of 168 days were carried out by following the macroscopic view, pH, sterility, content of tetracaine hydrochloride and detection of the degradation products. Also, values of the constant of degradation rate at different temperatures and t90% were calculated. The phosphate and acetate buffers provided satisfactory stability of tetracaine hydrochloride eyedrops, while borate buffer was not sufficient to maintain the pH value of the solution.

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