Evaluating the Role of Nanomontmorillonite in Bulk in Situ Radical Polymerization Kinetics of Butyl Methacrylate through a Simulation Model

2014 ◽  
Vol 53 (28) ◽  
pp. 11303-11311 ◽  
Author(s):  
Mohammad Nahid Siddiqui ◽  
Halim Hamid Redhwi ◽  
George D. Verros ◽  
Dimitris S. Achilias
Keyword(s):  
Simulation Model ◽  
Radical Polymerization ◽  
Polymerization Kinetics ◽  
Butyl Methacrylate ◽  
Kinetics Of

scholarly journals Phosphorylation of GAPVD1 Is Regulated by the PER Complex and Linked to GAPVD1 Degradation

2021 ◽  
Vol 22 (7) ◽  
pp. 3787
Author(s):  
Hussam Ibrahim ◽  
Philipp Reus ◽  
Anna Katharina Mundorf ◽  
Anna-Lena Grothoff ◽  
Valerie Rudenko ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Transcriptional Repression ◽  
Small Gtpase ◽  
Main Role ◽  
Interacting Proteins ◽  
Casein Kinase 1 ◽  
Bona Fide ◽  
Kinetics Of

Repressor protein period (PER) complexes play a central role in the molecular oscillator mechanism of the mammalian circadian clock. While the main role of nuclear PER complexes is transcriptional repression, much less is known about the functions of cytoplasmic PER complexes. We found with a biochemical screen for PER2-interacting proteins that the small GTPase regulator GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1), which has been identified previously as a component of cytoplasmic PER complexes in mice, is also a bona fide component of human PER complexes. We show that in situ GAPVD1 is closely associated with casein kinase 1 delta (CSNK1D), a kinase that regulates PER2 levels through a phosphoswitch mechanism, and that CSNK1D regulates the phosphorylation of GAPVD1. Moreover, phosphorylation determines the kinetics of GAPVD1 degradation and is controlled by PER2 and a C-terminal autoinhibitory domain in CSNK1D, indicating that the regulation of GAPVD1 phosphorylation is a novel function of cytoplasmic PER complexes and might be part of the oscillator mechanism or an output function of the circadian clock.

scholarly journals Effect of Na- and Organo-Modified Montmorillonite/Essential Oil Nanohybrids on the Kinetics of the In Situ Radical Polymerization of Styrene

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 474
Author(s):  
Ioannis S. Tsagkalias ◽  
Alexandra Loukidi ◽  
Stella Chatzimichailidou ◽  
Constantinos E. Salmas ◽  
Aris E. Giannakas ◽  
...  
Keyword(s):  
Essential Oil ◽  
Radical Polymerization ◽  
Food Packaging ◽  
In Situ Polymerization ◽  
Average Molecular Weight ◽  
Monomer Conversion ◽  
Hydroxyl Groups ◽  
Modified Montmorillonite ◽  
Kinetics Of

The great concern about the use of hazardous additives in food packaging materials has shown the way to new bio-based materials, such as nanoclays incorporating bioactive essential oils (EO). One of the still unresolved issues is the proper incorporation of these materials into a polymeric matrix. The in situ polymerization seems to be a promising technique, not requiring high temperatures or toxic solvents. Therefore, in this study, the bulk radical polymerization of styrene was investigated in the presence of sodium montmorillonite (NaMMT) and organo-modified montmorillonite (orgMMT) including thyme (TO), oregano (OO), and basil (BO) essential oil. It was found that the hydroxyl groups present in the main ingredients of TO and OO may participate in side retardation reactions leading to lower polymerization rates (measured gravimetrically by the variation of monomer conversion with time) accompanied by higher polymer average molecular weight (measured via GPC). The use of BO did not seem to affect significantly the polymerization kinetics and polymer MWD. These results were verified from independent experiments using model compounds, thymol, carvacrol and estragol instead of the clays. Partially intercalated structures were revealed from XRD scans. The glass transition temperature (from DSC) and the thermal stability (from TGA) of the nanocomposites formed were slightly increased from 95 to 98 °C and from 435 to 445 °C, respectively. Finally, better dispersion was observed when orgMMT was added instead of NaMMT.

Effect of pH on the Grain Size Dependence of Magnesium Corrosion

CORROSION ◽  
2012 ◽  
Vol 68 (6) ◽  
pp. 507-517 ◽  
Author(s):  
K. D. Ralston ◽  
G. Williams ◽  
N. Birbilis
Keyword(s):  
Grain Size ◽  
Corrosion Rate ◽  
Anodic Polarization ◽  
Localized Corrosion ◽  
Anodic Reaction ◽  
Left Behind ◽  
Kinetics Of ◽  
Electrode Technique

Prior works show that grain size can play a role in the corrosion of a metal; however, such works are nominally executed in a single electrolyte/environment at a single pH. In this work, the anodic and cathodic reaction kinetics of pure Mg specimens with grain sizes ranging from approximately 8 μm to 590 μm were compared as a function of pH in 0.1 mol dm−3 sodium chloride (NaCl) electrolytes using anodic polarization experiments and an in situ scanning vibrating electrode technique (SVET). Anodic polarization experiments showed that grain size is important in determining overall electrochemical response, but the environment dictates the form of the grain size vs. corrosion rate relationship (i.e., pH is the overall controlling factor). Consequently, the role of grain size upon corrosion cannot be fully assessed unless a variation in environment is simultaneously studied. For example, the anodic reaction, which dictates active corrosion, also dictates passivation, so the corrosion rate vs. grain size relationship has been shown to “flip” depending on pH. Further, SVET analysis of unpolarized Mg immersed in 0.1 mol dm−3 NaCl electrolyte at neutral pH showed that breakdown of passivity of cast Mg occurred after ~1 h immersion, giving filiform-like corrosion tracks. The front edges of these corrosion features were revealed as intense local anodes, while the remainder of the dark-corroded Mg surface, left behind as the anodes traversed the surface, became cathodically activated. In contrast, grain-refined Mg samples were significantly less susceptible to localized corrosion, and breakdown was not observed for immersion periods of up to 24 h.

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