Physical Characterization of Clostridium Difficile Toxins and Toxoids: Effect of the Formaldehyde Crosslinking on Thermal Stability

2008 ◽  
Vol 97 (9) ◽  
pp. 3735-3752 ◽  
Author(s):  
Maya S. Salnikova ◽  
Sangeeta B. Joshi ◽  
J. Howard Rytting ◽  
Michel Warny ◽  
C. Russell Middaugh
Keyword(s):  
Thermal Stability ◽  
Clostridium Difficile ◽  
Physical Characterization ◽  
Formaldehyde Crosslinking

New classes of porphyrazine macrocycles with annulated heterocyclic rings

2000 ◽  
Vol 04 (05) ◽  
pp. 474-483 ◽  
Author(s):  
SILVIA ANGELONI ◽  
CLAUDIO ERCOLANI
Keyword(s):  
Thermal Stability ◽  
Ring Opening ◽  
Physical Characterization ◽  
New Materials ◽  
Present Contribution ◽  
Physical Behaviour ◽  
Peripheral Ring ◽  
Metal Derivatives ◽  
Available Information

The present contribution summarizes the most recent results on the synthesis and chemical physical characterization of the new classes of porphyrazine macrocycles having annulated five- and seven-membered heterocyclic rings, i.e. tetrakis(thiadizole)porphyrazine, TTDPzH 2, tetrakis(selenodiazole)porphyrazine, TSeDPzH 2, tetrakis-2,3-(5,7dipheny-6H-1,4-diazepino)porphyrazine, Ph 8 DzPzH 2, and a number of their metal derivatives, prepared by using, respectively, 3,4-dicyano-1,2,5-thiadiazole, 3,4-dicyano-1,2,5-selenodiazole, and 5,7-diphenyl-2,3-dicyano-6H-1,4-diazepine as monomeric precursors. The available information indicates that, owing to the presence of electron rich and soft atoms ( S , Se ) inserted in the proximity of the porphyrazine core, the TTDPz and TSeDPz macrocycles, closely resembling their phthalocyanine analogues in terms of structural and electronic features and physical behaviour (solubility, thermal stability, vaporizability, etc.), might be promising new materials for applicative properties. Particularly interesting is the operated peripheral ring opening of the TSeDPz macroxycle leading to the formation of octaaminoporphyrazine, followed by its conversion to a tetrakis(pyrazino)porphyrazine. The macrocycles containing the Ph 8 DzPz skeleton, due to the presence of the external non planar diphenyldiazepine units, appear to exhibit a distinct physical behaviour, which can be probably modulated by appropriate alternative substitutions in the 5, 6, and 7 positions of the diazepine rings.

scholarly journals Characterization of Sardinian Bentonite

2018 ◽  
Author(s):  
Alberto Mannu ◽  
Gina Vlahopoulou ◽  
Giacomo Luigi Petretto ◽  
Veronica Sireus ◽  
Gabriele Mulas
Keyword(s):  
Thermal Stability ◽  
Geographical Origin ◽  
Physical Characteristics ◽  
Laboratory Scale ◽  
Physical Characterization ◽  
Stability Evaluation ◽  
Characterization Techniques ◽  
Filling Materials

The employment of clays in industry and on laboratory scale is still of interest, despite their long history. The chemical-physical characteristics of such material are strongly related to their geographical origin and the availability of proper characterization techniques is of great importance in order to gain as more information about their behavior when utilized as filling materials. In the present contribute a physical characterization by meaning of Thermogravimetry and N2 physisorption, including a thermal stability evaluation, of samples of Sardinian bentonite collected from the Alghero area (Italy) is reported.

scholarly journals The Preparation and Characterization of Chitosan-Based Hydrogels Cross-Linked by Glyoxal

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2449
Author(s):  
Beata Kaczmarek-Szczepańska ◽  
Olha Mazur ◽  
Marta Michalska-Sionkowska ◽  
Krzysztof Łukowicz ◽  
Anna Maria Osyczka
Keyword(s):  
Thermal Stability ◽  
Tannic Acid ◽  
Dental Pulp ◽  
Blood Compatibility ◽  
Dental Pulp Cells ◽  
Preliminary Assessment ◽  
Human Dental Pulp Cells ◽  
Human Dental Pulp ◽  
Pulp Cells

In this study, hydrogels based on chitosan cross-linked by glyoxal have been investigated for potential medical applications. Hydrogels were loaded with tannic acid at different concentrations. The thermal stability and the polyphenol-releasing rate were determined. For a preliminary assessment of the clinical usefulness of the hydrogels, they were examined for blood compatibility and in the culture of human dental pulp cells (hDPC). The results showed that after immersion in a polyphenol solution, chitosan/glyoxal hydrogels remain nonhemolytic for erythrocytes, and we also did not observe the cytotoxic effect of hydrogels immersed in tannic acid (TA) solutions with different concentration. Tannic acid was successfully released from hydrogels, and its addition improved material thermal stability. Thus, the current findings open the possibility to consider such hydrogels in clinics.

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