Physicochemical characterization of the thermal aging of insulating paper in power transformers

Author(s):  
M.C. Lessard ◽  
L. Van Nifterik ◽  
J.F. Penneau ◽  
R. Grob ◽  
M. Masse
2021 ◽  
Vol 31 (31) ◽  
pp. 125-136
Author(s):  
Jelena Planojević ◽  
J. Lukić ◽  
Valentina Vasović ◽  
D. Mihajlović ◽  
Jelena Janković ◽  
...  

The need to increase the productivity and capacity of power transformers has conditioned the production of insulating papers of a higher thermal class. For this purpose, various techniques of solid insulation modification were applied, which enable the increase in thermal and chemical stability of the insulating paper during the operation of the transformer. The applied additives, primarily dicyandiamide (DICY) and polyacrylamide (PAM), are one form of cellulose modification in the final stages of paper production. A significant difference between the papers is the nitrogen content in the paper, which is characterized by the addition of amine compounds (additives). The paper presents the application of infrared spectroscopy with totally attenuated reflection (FTIR-ATR) in the characterization of paper samples. The aim is to observe the difference between regularly kraft and thermally upgraded paper reflected in the presence or absence of characteristic functional groups for additives. The strip identification at 2194-2154 cm-1 confirmed the presence of dicyandiamide additives (DICY) in the spectrum of the sample of thermally upgraded paper, which is different compared with the spectrum of regular kraft paper.


2019 ◽  
Vol 38 (2) ◽  
pp. 385 ◽  
Author(s):  
Marwa M. El-Naggar ◽  
Wael S. I. Abou-Elmagd ◽  
Ashraf Suloma ◽  
Hamza A. El-Shabaka ◽  
Magdy T. Khalil ◽  
...  

Author(s):  
Kumar P ◽  
S Kumar ◽  
A Kumar ◽  
M Chander

The purpose of this study was to prepare and characterize solid dispersions of the antibacterial agent Cefdinir with PEG 4000 and PVP K-30 with a view to improve its dissolution properties. Investigations of the properties of the dispersions were performed using release studies, X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR). The results obtained showed that the rate of dissolution of Cefdinir was considerably improved when formulated in solid dispersions with PVP K-30 and PEG 4000 as compared with pure drug and physical mixtures. The results from XRD studies showed the transition of crystalline nature of drug to amorphous form, while FTIR studies demonstrated the absence of drug-carriers interaction.


2013 ◽  
Vol 21 (2) ◽  
pp. 108-114 ◽  
Author(s):  
Girijesh Patel ◽  
Amit Gupta ◽  
Akshita Gupta ◽  
Manisha Mishra ◽  
Pradhyumna Singh ◽  
...  

Author(s):  
Václav Kašička ◽  
Dušan Koval ◽  
Veronika Šolínová ◽  
Petra Sázelová ◽  
Zdeněk Prusík

Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 544
Author(s):  
Giuditta Guerrini ◽  
Antonio Vivi ◽  
Sabrina Gioria ◽  
Jessica Ponti ◽  
Davide Magrì ◽  
...  

Adjuvants have been used for decades to enhance the immune response to vaccines, in particular for the subunit-based adjuvants. Physicochemical properties of the adjuvant-protein antigen complexes, such as size, morphology, protein structure and binding, influence the overall efficacy and safety of the vaccine. Here we show how to perform an accurate physicochemical characterization of the nanoaluminum–ovalbumin complex. Using a combination of existing techniques, we developed a multi-staged characterization strategy based on measurements of increased complexity. This characterization cascade has the advantage of being very flexible and easily adaptable to any adjuvant-protein antigen combinations. It will contribute to control the quality of antigen–adjuvant complexes and immunological outcomes, ultimately leading to improved vaccines.


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