Mass and charge density effects on the saturation kinetics of polypyrrole doped with dodecylbenzene sulfonate

2016 ◽  
Vol 28 (6) ◽  
pp. 760-771 ◽  
Author(s):  
Vinithra Venugopal ◽  
Travis Hery ◽  
Vijay Venkatesh ◽  
Vishnu Baba Sundaresan
Keyword(s):  
Charge Density ◽  
Conducting Polymer ◽  
Kinetics Model ◽  
Step Response ◽  
Charge Storage ◽  
Density Effects ◽  
Redox Sites ◽  
Trade Offs ◽  
Saturation Kinetics ◽  
Polymer Devices

In this article, the saturation kinetics model that describes chronoamperometric response of PPy(DBS) in our recently published work is extended to study the effect of mass and charge density on the step response of PPy(DBS). The saturation kinetics model is based on a mechanistic approach for charge storage in conducting polymers and leads to the development of structure-dependent input-output relationships to develop a cation concentration sensor. In this article, we demonstrate the use of poles and residues in the saturation kinetics model to deconstruct the chronoamperometric and chronocoulometric response by seperating the contributions from double layer charge accumulation and faradaic ion transport. We show that: (i) the number of redox sites, and therefore the number of ingressing ions at saturation, is directly proportional to the mass of the conducting polymer, (ii) the accessibility of these redox sites associated with ion ingress is inversely proportional to the conducting polymer charge density, (iii) the rate of ion ingress is found to be inversely proportional to mass and charge density, due to the decrease in the driving force per unit redox site and redox site accessibility, respectively. For lower charge densities, the mass has a dominant effect on saturation and rate of ion ingress, with charge density effects becoming apparent as it increases. The saturation charges obtained are consistent with the peak charges during cyclic voltammetry, thus validating the mechanistic interpretations. The findings of this article highlight the trade-offs between charge storage and transport properties for conducting polymer devices.

Analysis of BP response and Ca2+ metabolism using the saturation kinetics model

1987 ◽  
Vol 253 (3) ◽  
pp. R501-R508
Author(s):  
N. Karanja ◽  
J. A. Metz ◽  
L. P. Mercer ◽  
D. A. McCarron
Keyword(s):  
Blood Pressure ◽  
Body Weight ◽  
Bone Density ◽  
Spontaneously Hypertensive Rat ◽  
Kinetics Model ◽  
Maximal Dose ◽  
Spontaneously Hypertensive ◽  
Rates Of Change ◽  
Saturation Kinetics ◽  
Serum Ionized Calcium

The provision of supplemental dietary calcium (dCa) lowers blood pressure (BP) in the spontaneously hypertensive rat (SHR). Whether calcium's antihypertensive effects can be expressed in the presence of potentially hypertensinogenic nutrients is not known. Furthermore, the amount of dCa required to attenuate hypertension in the SHR remains undetermined. Along with establishing the effects of dCa on BP under conditions of a high Na+ intake, we sought to define the lowest dose of dCa associated with the greatest attenuation in arterial pressure in the young SHR. Thirty-five 6-wk-old SHR were fed one of five diets containing either 0.1, 0.25, 0.5, 1.0, or 2.0% dCa. All diets contained 1.0% Na+. The rates of change (delta) in body weight, BP, and serum ionized calcium were determined between 6 and 20 wk of age. Bone density (BD) was measured only at 20 wk of age. The data were analyzed using the saturation kinetics model. Results indicate that the half-maximal dose (K50) of dCa needed to lower pressure is 0.67 +/- 0.18%, which is higher than the K50 for weight (0.23 +/- 0.18) and BD (0.36 +/- 0.22). It is concluded that supplemental dCa lowers BP despite a high Na+ intake. Furthermore, a dose of approximately 1.5 dCa is sufficient to attenuate the rate of hypertension in the young growing SHR.

Relationship of feed intake with cystine availability and wool growth in Merino wethers

1993 ◽  
Vol 44 (5) ◽  
pp. 973 ◽  
Author(s):  
GJ Lee ◽  
AJ Williams
Keyword(s):  
Sulfur Content ◽  
Fibre Diameter ◽  
Kinetics Model ◽  
Similar Proportion ◽  
Standard Diet ◽  
Growth Responses ◽  
Irreversible Loss ◽  
Wool Growth ◽  
Saturation Kinetics ◽  
The Relationship

Two experiments were conducted to characterize the relationship between nutrient supply and the rate of wool growth. We concentrated on the accepted view that the rate of wool growth in Merino sheep is primarily limited by the availability of sulfur amino acids, which are largely determined by diet intake and its interaction with microbial fermentation in the reticulo-rumen. In the first experiment, the effects of variable intakes of two diets (one including 10% fishmeal) by sheep on the rate of irreversible loss of cystine and plasma cystine concentration were investigated. Nitrogen intake (N) was positively and linearly related to both the irreversible loss rate and the plasma concentration of cystine, with no effects of diet per se. In the second experiment, the same dietary treatments were imposed on 39 wethers for 16 weeks following an 8 week pre-experimental period. The monthly rates of wool growth, average fibre diameter and sulfur content of the wool were measured and related to various components of intake. The rate of wool growth responded in a positive curvilinear decreasing manner to changes in intake, the response requiring 2 months to stabilize. There was no significant effect of diet when daily intake was expressed as g N kg-0.75 liveweight. Including the covariate (wool growth when fed the standard diet), the quadratic linear model accounted for 90% of the total variation in wool growth. Responses in fibre diameter and its variation, and wool sulfur content were similar to those of wool growth, in that they were positive and did not equilibrate quickly. A saturation kinetics model of the relationship between daily N intake (g N kg 0.75 liveweight) and wool growth accounted for a similar proportion of the variation as did a linear (with quadratic term) model without the covariate. It is concluded that the saturation kinetics model may be useful for more comprehensive comparisons of both the genetic potential and the sensitivity of wool growth to environmental changes.

scholarly journals Graphene/oligoaniline based supercapacitors: Towards conducting polymer materials with high rate charge storage

2019 ◽  
Vol 19 ◽  
pp. 137-147 ◽  
Author(s):  
Haosen Wang ◽  
Ziwei Yu ◽  
Maher F. El-Kady ◽  
Mackenzie Anderson ◽  
Matthew D. Kowal ◽  
...  
Keyword(s):  
Conducting Polymer ◽  
Polymer Materials ◽  
High Rate ◽  
Charge Storage

Diverse porphyrin dimers as candidates for high-density charge-storage molecules

2006 ◽  
Vol 10 (01) ◽  
pp. 22-32 ◽  
Author(s):  
Andrey B. Lysenko ◽  
Patchanita Thamyongkit ◽  
Izabela Schmidt ◽  
James R. Diers ◽  
David F. Bocian ◽  
...  
Keyword(s):  
Charge Density ◽  
Cross Sectional Area ◽  
Information Storage ◽  
Redox Activity ◽  
Charge Storage ◽  
Sectional Area ◽  
Storage Medium ◽  
Cross Sectional ◽  
Porphyrin Dimers ◽  
Large Charge

Porphyrinic molecules have been shown to be viable candidates for a molecular-based information storage medium on the basis of redox activity. An optimal redox-based information storage medium requires a large charge density in the molecular footprint on the anchoring substrate. The use of dimeric versus monomeric architectures affords one route to achieving increased charge density without sacrificing surface cross sectional area. Towards this goal, a series of zinc and cobalt containing porphyrin dimers has been prepared and characterized. The interporphyrin linkages in the dimers include p-phenylene, ethynyl, 1,4-butadiynyl, and ethynylphenylethynyl joining porphyrin meso-positions; Crossley-type fusion bridging porphyrin β-positions, and Osuka-type triple fusions bridging one meso- and two β-positions. The electrochemical features of each dimer have been evaluated.

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