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Optimum periodicity of repeated contractile actions applied in mass transport.

Ahn S, Lee SJ - Sci Rep (2015)

Bottom Line: The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions.Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system.In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport.

View Article: PubMed Central - PubMed

Affiliation: 1] Biofluid and Biomimic Research Center, Pohang University of Science and Technology, Pohang, 790-784, Korea [2] Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea.

ABSTRACT
Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

No MeSH data available.


(a) Design of the contractile action on flow. By repeating on−off−on position, one valve function is designed (upper). Representative data of the one-valve system. During the designed off-time (toff), the inlet flow stops. During the taper time (ttaper), detection of permeate molecules slows followed by complete stop-time (tstop). Right after the toff starts, there is a responding time (tresponding) at which the flow stops suddenly and generates back pressure inside the cell. According to the inlet frequency (fin), the outlet frequency is modulated. Right after the toff, the first maximum outlet frequency is determined as recover frequency (frecover) after that ith frequency is determined in a sequence. (b) [I] toff vs. tresponding [II] toff vs. ttaper. tresponding and ttaper are independent of toff, reflecting system-specific features. [III] toff vs. maximum normalized frequency (frecover/fin). The frequency increase is saturated at a critical point, so the optimum time (toptinum) is determined. (c) toff vs. frecover/fin with changing r (left) and fin (right). The critical point move to higher toff by decreasing r, whereas a higher fin contributes to the increase in the magnitude of frecover/fin. (d) Fitting results of the trecover vs. toff in the two regions: [I] in the range of toff ≤ topt, K(r) toff + 1/fin relation is satisfied. [II] in the range of toff > topt, K(r) [toff + (toff − topt)] + 1/fin relation is applied. The proportional factor K is also a function of r. (e) Summary of one periodicity composed of toff and trecover as a function of toff, toptinum, frecover and fin.
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f4: (a) Design of the contractile action on flow. By repeating on−off−on position, one valve function is designed (upper). Representative data of the one-valve system. During the designed off-time (toff), the inlet flow stops. During the taper time (ttaper), detection of permeate molecules slows followed by complete stop-time (tstop). Right after the toff starts, there is a responding time (tresponding) at which the flow stops suddenly and generates back pressure inside the cell. According to the inlet frequency (fin), the outlet frequency is modulated. Right after the toff, the first maximum outlet frequency is determined as recover frequency (frecover) after that ith frequency is determined in a sequence. (b) [I] toff vs. tresponding [II] toff vs. ttaper. tresponding and ttaper are independent of toff, reflecting system-specific features. [III] toff vs. maximum normalized frequency (frecover/fin). The frequency increase is saturated at a critical point, so the optimum time (toptinum) is determined. (c) toff vs. frecover/fin with changing r (left) and fin (right). The critical point move to higher toff by decreasing r, whereas a higher fin contributes to the increase in the magnitude of frecover/fin. (d) Fitting results of the trecover vs. toff in the two regions: [I] in the range of toff ≤ topt, K(r) toff + 1/fin relation is satisfied. [II] in the range of toff > topt, K(r) [toff + (toff − topt)] + 1/fin relation is applied. The proportional factor K is also a function of r. (e) Summary of one periodicity composed of toff and trecover as a function of toff, toptinum, frecover and fin.

Mentions: With a fixed fin = 4 (min−1) and r = 0.01 cm3/min, temperature at the middle of the designed nanocomposite pellet is controlled (Figure 4a). The off position in the valve function is provided by switching the temperature from 60°C to 20°C. The cooling process is only applied to the middle section on 2 cm length region (out of 10 cm total tube length) to induce temperature gradient. The frequency maintains a regular pattern (4 min−1) before changing to the off-state. However, during the responding time (trespond), permeate movement is suddenly delayed by the contractile actions in the off-state. This phenomenon is caused by the swelling procedure of the nanocomposite, which increases the back pressure caused by sudden water absorption. After the abrupt stop of permeate movement, the decreased water flow induces an incremental decrease in fout, forming a tapering zone (ttaper). Once most of the permeates exit the off-zone, the permeate elution is completely stopped until the designed toff ends. When the on-position state and flow are both regained after toff, the permeates are detected in a high frequency (frecover) because of accumulative congestion during the period of toff. The frequency stabilizes during the recovering time (trecover) to regain original frequency (fin = fi), where fi is the ith frequency after frecover.


Optimum periodicity of repeated contractile actions applied in mass transport.

Ahn S, Lee SJ - Sci Rep (2015)

(a) Design of the contractile action on flow. By repeating on−off−on position, one valve function is designed (upper). Representative data of the one-valve system. During the designed off-time (toff), the inlet flow stops. During the taper time (ttaper), detection of permeate molecules slows followed by complete stop-time (tstop). Right after the toff starts, there is a responding time (tresponding) at which the flow stops suddenly and generates back pressure inside the cell. According to the inlet frequency (fin), the outlet frequency is modulated. Right after the toff, the first maximum outlet frequency is determined as recover frequency (frecover) after that ith frequency is determined in a sequence. (b) [I] toff vs. tresponding [II] toff vs. ttaper. tresponding and ttaper are independent of toff, reflecting system-specific features. [III] toff vs. maximum normalized frequency (frecover/fin). The frequency increase is saturated at a critical point, so the optimum time (toptinum) is determined. (c) toff vs. frecover/fin with changing r (left) and fin (right). The critical point move to higher toff by decreasing r, whereas a higher fin contributes to the increase in the magnitude of frecover/fin. (d) Fitting results of the trecover vs. toff in the two regions: [I] in the range of toff ≤ topt, K(r) toff + 1/fin relation is satisfied. [II] in the range of toff > topt, K(r) [toff + (toff − topt)] + 1/fin relation is applied. The proportional factor K is also a function of r. (e) Summary of one periodicity composed of toff and trecover as a function of toff, toptinum, frecover and fin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306965&req=5

f4: (a) Design of the contractile action on flow. By repeating on−off−on position, one valve function is designed (upper). Representative data of the one-valve system. During the designed off-time (toff), the inlet flow stops. During the taper time (ttaper), detection of permeate molecules slows followed by complete stop-time (tstop). Right after the toff starts, there is a responding time (tresponding) at which the flow stops suddenly and generates back pressure inside the cell. According to the inlet frequency (fin), the outlet frequency is modulated. Right after the toff, the first maximum outlet frequency is determined as recover frequency (frecover) after that ith frequency is determined in a sequence. (b) [I] toff vs. tresponding [II] toff vs. ttaper. tresponding and ttaper are independent of toff, reflecting system-specific features. [III] toff vs. maximum normalized frequency (frecover/fin). The frequency increase is saturated at a critical point, so the optimum time (toptinum) is determined. (c) toff vs. frecover/fin with changing r (left) and fin (right). The critical point move to higher toff by decreasing r, whereas a higher fin contributes to the increase in the magnitude of frecover/fin. (d) Fitting results of the trecover vs. toff in the two regions: [I] in the range of toff ≤ topt, K(r) toff + 1/fin relation is satisfied. [II] in the range of toff > topt, K(r) [toff + (toff − topt)] + 1/fin relation is applied. The proportional factor K is also a function of r. (e) Summary of one periodicity composed of toff and trecover as a function of toff, toptinum, frecover and fin.
Mentions: With a fixed fin = 4 (min−1) and r = 0.01 cm3/min, temperature at the middle of the designed nanocomposite pellet is controlled (Figure 4a). The off position in the valve function is provided by switching the temperature from 60°C to 20°C. The cooling process is only applied to the middle section on 2 cm length region (out of 10 cm total tube length) to induce temperature gradient. The frequency maintains a regular pattern (4 min−1) before changing to the off-state. However, during the responding time (trespond), permeate movement is suddenly delayed by the contractile actions in the off-state. This phenomenon is caused by the swelling procedure of the nanocomposite, which increases the back pressure caused by sudden water absorption. After the abrupt stop of permeate movement, the decreased water flow induces an incremental decrease in fout, forming a tapering zone (ttaper). Once most of the permeates exit the off-zone, the permeate elution is completely stopped until the designed toff ends. When the on-position state and flow are both regained after toff, the permeates are detected in a high frequency (frecover) because of accumulative congestion during the period of toff. The frequency stabilizes during the recovering time (trecover) to regain original frequency (fin = fi), where fi is the ith frequency after frecover.

Bottom Line: The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions.Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system.In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport.

View Article: PubMed Central - PubMed

Affiliation: 1] Biofluid and Biomimic Research Center, Pohang University of Science and Technology, Pohang, 790-784, Korea [2] Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea.

ABSTRACT
Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

No MeSH data available.