Zahra Niroobakhsh

Dr. Zahra Niroobakhsh

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Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 January 2023 in Small
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Journal Article
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HHHouman Honaryar
Houman Honaryar
SASaba Amirfattahi
Saba Amirfattahi
Zahra NiroobakhshZahra Niroobakhsh
Zahra Niroobakhsh

3 May 2019 in Physical Review Letters
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Zahra NiroobakhshZahra Niroobakhsh
Zahra Niroobakhsh
JLJacob A. LaNasa
Jacob A. LaNasa
ABAndrew Belmonte
Andrew Belmonte
RHRobert J. Hickey
Robert J. Hickey
Surfactant molecules have been extensively used as emulsifying agents to stabilize immiscible fluids. Droplet stability has been shown to be increased when ordered nanoscale phases form at the interface of the two fluids due to surfactant association. Here, we report on using mixtures of a cationic surfactant and long chained alkenes with polar head groups [e.g., cetylpyridinium chloride (CPCl) and oleic acid] to create an ordered nanoscale lamellar morphology at aqueous-oil interfaces. The self-assembled nanostructure at the liquid-liquid interface was characterized using small-angle x-ray scattering, and the mechanical properties were measured using interfacial rheology. We hypothesize that the resulting lamellar morphology at the liquid-liquid interface is driven by the change in critical packing parameter when the CPCl molecules are diluted by the presence of the long chain alkenes with polar head groups, which leads to a spherical micelle-to-lamellar phase transition. The work presented here has larger implications for using nanostructured interfacial material to separate different fluids in flowing conditions for biosystems and in 3D printing technology.

6 November 2017 in Physical Review E
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Zahra NiroobakhshZahra Niroobakhsh
Zahra Niroobakhsh
MLMatthew Litman
Matthew Litman
ABAndrew Belmonte
Andrew Belmonte
We present an experimental study of pattern formation during the penetration of an aqueous surfactant solution into a liquid fatty acid in a Hele-Shaw cell. When a solution of the cationic surfactant cetylpyridinium chloride is injected into oleic acid, a wide variety of fingering patterns are observed as a function of surfactant concentration and flow rate, which are strikingly different than the classic Saffman-Taylor (ST) instability. We observe evidence of interfacial material forming between the two liquids, causing these instabilities. Moreover, the number of fingers decreases with increasing flow rate Q, while the average finger width increases with Q, both trends opposite to the ST case. Bulk rheology on related mixtures indicates a gel-like state. Comparison of experiments using other oils indicates the importance of pH and the carboxylic head group in the formation of the surfactant–fatty acid material.

27 September 2021 in Macromolecular Rapid Communications
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HHHouman Honaryar
Houman Honaryar
JLJacob A. LaNasa
Jacob A. LaNasa
ELElisabeth C. Lloyd
Elisabeth C. Lloyd
RHRobert J. Hickey
Robert J. Hickey
Zahra NiroobakhshZahra Niroobakhsh
Zahra Niroobakhsh

18 January 2021 in Journal of Fluid Mechanics
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MZMeng Zhao
Meng Zhao
Zahra NiroobakhshZahra Niroobakhsh
Zahra Niroobakhsh
JLJohn Lowengrub
John Lowengrub
SLShuwang Li
Shuwang Li
The flow in a Hele-Shaw cell with a time-increasing gap poses a unique shrinking interface problem. When the upper plate of the cell is lifted perpendicularly at a prescribed speed, the exterior less viscous fluid penetrates the interior more viscous fluid, which generates complex, time-dependent interfacial patterns through the Saffman–Taylor instability. The pattern formation process sensitively depends on the lifting speed and is still not fully understood. For some lifting speeds, such as linear or exponential speed, the instability is transient and the interface eventually shrinks as a circle. However, linear stability analysis suggests there exist shape invariant shrinking patterns if the gap .

14 June 2024 in Small
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Journal Article
Closed access
HHHouman Honaryar
Houman Honaryar
SASaba Amirfattahi
Saba Amirfattahi
DNDuoc Nguyen
Duoc Nguyen
KKKyungtae Kim
Kyungtae Kim
JSJulian C. Shillcock
Julian C. Shillcock
Zahra NiroobakhshZahra Niroobakhsh
Zahra Niroobakhsh