Solid-State Stability of Spray-Dried Insulin Powder for Inhalation: Chemical Kinetics and Structural Relaxation Modeling of Exubera Above and Below the Glass Transition Temperature

2010 ◽  
Vol 99 (9) ◽  
pp. 3698-3710 ◽  
Author(s):  
Negar Sadrzadeh ◽  
Danforth P. Miller ◽  
David Lechuga-Ballesteros ◽  
Nancy J. Harper ◽  
Cynthia L. Stevenson ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Solid State ◽  
Chemical Kinetics ◽  
Structural Relaxation ◽  
Solid State Stability ◽  
Spray Dried

scholarly journals Effects of Annealing on Enthalpy Recovery and Nanomechanical Behaviors of a La-Based Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 579
Author(s):  
Ting Shi ◽  
Lanping Huang ◽  
Song Li
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Nanoindentation Measurement

Structural relaxation and nanomechanical behaviors of La65Al14Ni5Co5Cu9.2Ag1.8 bulk metallic glass (BMG) with a low glass transition temperature during annealing have been investigated by calorimetry and nanoindentation measurement. The enthalpy release of this metallic glass is deduced by annealing near glass transition. When annealed below glass transition temperature for 5 min, the recovered enthalpy increases with annealing temperature and reaches the maximum value at 403 K. After annealed in supercooled liquid region, the recovered enthalpy obviously decreases. For a given annealing at 393 K, the relaxation behaviors of La-based BMG can be well described by the Kohlrausch-Williams-Watts (KWW) function. The hardness, Young’s modulus, and serrated flow are sensitive to structural relaxation of this metallic glass, which can be well explained by the theory of solid-like region and liquid-like region. The decrease of ductility and the enhancement of homogeneity can be ascribed to the transformation from liquid-like region into solid-like region and the reduction of the shear transition zone (STZ).

scholarly journals Long-Term Physical (In)Stability of Spray-Dried Amorphous Drugs: Relationship with Glass-Forming Ability and Physicochemical Properties

Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 425 ◽  
Author(s):  
Edueng ◽  
Bergström ◽  
Gråsjö ◽  
Mahlin
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physicochemical Properties ◽  
Physical Stability ◽  
Glass Forming Ability ◽  
Melt Quenching ◽  
Glass Forming ◽  
Spray Dried

This study shows the importance of the chosen method for assessing the glass-forming ability (GFA) and glass stability (GS) of a drug compound. Traditionally, GFA and GS are established using in situ melt-quenching in a differential scanning calorimeter. In this study, we included 26 structurally diverse glass-forming drugs (i) to compare the GFA class when the model drugs were produced by spray-drying with that when melt-quenching was used, (ii) to investigate the long-term physical stability of the resulting amorphous solids, and (iii) to investigate the relationship between physicochemical properties and the GFA of spray-dried solids and their long-term physical stability. The spray-dried solids were exposed to dry (<5% RH) and humid (75% RH) conditions for six months at 25 °C. The crystallization of the spray-dried solids under these conditions was monitored using a combination of solid-state characterization techniques including differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. The GFA/GS class assignment for 85% of the model compounds was method-dependent, with significant differences between spray-drying and melt-quenching methods. The long-term physical stability under dry condition of the compounds was predictable from GFA/GS classification and glass transition and crystallization temperatures. However, the stability upon storage at 75% RH could not be predicted from the same data. There was no strong correlation between the physicochemical properties explored and the GFA class or long-term physical stability. However, there was a slight tendency for compounds with a relatively larger molecular weight, higher glass transition temperature, higher crystallization temperature, higher melting point and higher reduced glass transition temperature to have better GFA and better physical stability. In contrast, a high heat of fusion and entropy of fusion seemed to have a negative impact on the GFA and physical stability of our dataset.

Water sorption isotherms and glass transition temperature of spray dried tomato pulp

2008 ◽  
Vol 85 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Athanasia M. Goula ◽  
Thodoris D. Karapantsios ◽  
Dimitris S. Achilias ◽  
Konstantinos G. Adamopoulos
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Water Sorption ◽  
Sorption Isotherms ◽  
Tomato Pulp ◽  
Spray Dried ◽  
Water Sorption Isotherms

The Influence of Gamma Radiation on the Glass Transition of Hydroxyapatite/Poly L-Lactide Composite

2007 ◽  
Vol 555 ◽  
pp. 497-502
Author(s):  
Dejan Miličević ◽  
S. Trifunović ◽  
N. Ignjatović ◽  
E. Suljovrujić
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Absorbed Dose ◽  
Gel Permeation Chromatography ◽  
Chain Scission ◽  
Scanning Calorimetry ◽  
Dsc Measurements

Hydroxyapatite/poly L-lactide (HAp/PLLA) is a composite biomaterial which has been widely utilized for substitution and reparation of the hard bone tissue. It is well known that gamma irradiation has been successfully employed in the modification/sterilization of such porous composites and that it has advantages over other procedures. In this study, differential scanning calorimetry (DSC) measurements were made to investigate the influence of the radiation on glass transition behavior and structural relaxation, as well as to estimate the activation energy for this process. The apparent activation energy ΔH* for structural relaxation in the glass transition region was determined on the basis of the heating rate dependence of the glass transition temperature Tg. Furthermore, the results were correlated with those obtained by gel permeation chromatography (GPC). Our findings support the fact that the radiation-induced chain scission in the PLLA phase is the main reason for the decrease of the glass transition temperature and/or activation energy with the absorbed dose.

Glass transformation phenomena in bulk and film amorphous selenium via DSC heating and cooling scans

1990 ◽  
Vol 5 (4) ◽  
pp. 789-794 ◽  
Author(s):  
S. Yannacopoulos ◽  
S.O. Kasap
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Amorphous Selenium ◽  
Retardation Time ◽  
Transformation Kinetics ◽  
Glass Transformation ◽  
Constant Rate ◽  
The Mean

Recently there has been an emphasis on the importance of using cooling scans in DSC experiments in studying the glass transformation kinetics of glasses. The physical interpretation of the apparent activation energy from DSC heating scans has been questioned as not being meaningful. The present paper reports glass transition temperature (Tg) measurements derived from Differential Scanning Calorimetry (DSC) experiments on bulk and film amorphous selenium samples subjected to heating, at constant rate r, and cooling, at constant rate q, scans. Film samples were prepared by thermal evaporation techniques in vacuum. It is shown that for both bulk and film forms of a–Se, within experimental errors, log(r/T2gm) vs 1/Tgm plot where Tgm is the peak glass transformation temperature, and log(r) vs 1/Tgh plot, where Tgh is the glass transition onset temperature from DSC heating scans, are parallel to the log(q) vs 1/Tgc plot where Tgc is the glass transition temperature from cooling scans. Within the Hutchinson and Kovacs formulation of the glass transformation phenomenon, the results imply that the structural contribution to the mean retardation time, τ, is negligible in comparison with the temperature dependent part. The mean structural relaxation time for both bulk and film forms was found to exhibit a typical Vogel-Tammann-Fulcher type of temperature dependence. Furthermore, the structural relaxation rate was observed to be inversely proportional to the viscosity, η(T), implying that the mean structural retardation time is proportional to the viscosity, τ ∼ η. The results also confirm that the earlier studies of glass transformation kinetics in a–Se utilizing only DSC heating scans remain meaningful.

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