The prediction of water activity in aqueous solutions in connection with intermediate moisture foods IV. aW Prediction in aqueous non electrolyte solutions

2007 ◽  
Vol 15 (1) ◽  
pp. 59-70 ◽  
Author(s):  
J. CHIRIFE ◽  
C. FERRO FONTAN ◽  
E.A. BENMERGUI
Keyword(s):  
Aqueous Solutions ◽  
Water Activity ◽  
Electrolyte Solutions

Polypyrrole Actuator Operating Characteristicsin Electrolyte Solution Mixed with Methanol

2013 ◽  
Vol 300-301 ◽  
pp. 1352-1355 ◽  
Author(s):  
Futo Tsumuji ◽  
Daiki Hoshino ◽  
Shou Ogihara ◽  
Zong Fan Duan ◽  
Yutaro Suzuki ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Electrolyte Solution ◽  
Marked Improvement ◽  
Electrolyte Solutions ◽  
Rapid Decrease ◽  
The Other ◽  
Other Hand ◽  
Deformation Behaviors

In this work, a PPy actuator was fabricated by galvanostatic electropolymerization. The electrochemical deformation behaviors of the PPy actuator were investigated in aqueous solutions of an electrolyte, lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), containing different concentrations of methanol. Marked improvement of the actuating strain of approximately 9% was achieved when the actuator was driven by a potential between –1 and 1 V in the LiTFSI electrolyte containing 40 to 50% of methanol under a load stress of 0. 3 MPa. On the other hand, the actuator functioned in the electrolyte solutions containing more than 60% of methanol showed rapid decrease of the actuating strain and the electrochemical creep after repeated actuations. Possible mechanisms for these behaviors were discussed.

scholarly journals What properties of non-electrolyte solutions does a DNA molecule feel?

2021 ◽  
Vol 13 (2) ◽  
pp. 129-136
Author(s):  
George G. Malenkov ◽  
Keyword(s):  
Relative Humidity ◽  
Ethylene Glycol ◽  
Water Activity ◽  
Hyperfine Splitting ◽  
Solvent Polarity ◽  
Electrolyte Solutions ◽  
Water Solutions ◽  
Hyperfine Splitting Constant ◽  
Splitting Constant ◽  
In The Beginning

As early as in 1953 it was reported that at low relative humidity of the atmosphere (about 70 %) DNA films were in A-form, while at higher humidity (more than 80%) they were in B-form. Relative humidity of the atmosphere corresponds to the water activity in the system. It was found in the beginning of the 70th that DNA transfers to the A-form when non-electrolytes, such as monoatomic alcohols, dioxane, tetrahydrofurane were added to water. It was reasonable to suppose that B to A transition of DNA occurs in the non-electrolyte solutions at the same values af water activity as in the moist atmosphere. This prediction was borne out. But in water solutions of very polar non-electrolytes such as methanol and ethylene glycol B to A DNA does not occur even at very low water activity values. It was supposed that A form of DNA can arise only in the medium with sufficiently low polarity. We used hyperfine splitting constant (A) of a nitroxide spin label determined from the EPR spectra as a measure of the liquid solvent polarity. It was found that DNA transition into B form occurs when A reached a certain value. Polarity of methanol and ethylene glycol is much higher than that of the solutions in which B to A DNA transition takes place. This transition also occurs in water solutions of trifluoroethanol. But in these solutions the transition takes place at hyperfine splitting values, which are much greater than in other non-electrolyte solutions. Water activity in the zone of B-A DNA transition in trifluoroethanol solutions does not correspond water activity which was calculated for other nob-electrolyte solutions in which B-A transition is observed.

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