Center for Soft Matter and Biological Physics Friday Discussion Meetings

Fall 2018

Organizer: Vinh Nguyen

These meetings occur on Fridays from 4:00pm to 5:00pm in Robeson 304 (unless otherwise indicated)

August 2018
August 24

Friday 4:00pm
304 Robeson Hall
(poster)

Faculty Meeting (No CSB Discussion Meeting)

Organizer: Vinh Nguyen

August 31

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

September 2018
September 7

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

September 14

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

September 21

Friday 4:00pm
304 Robeson Hall
(poster)

Deepali Shirsekar (Mechanical Engineering)

“Bidirectional Reflectance Measurement of Black Coating Z302 for use in Optical Instrument Design ”

The bidirectional reflectance distribution function (BRDF) plays a fundamental role in the optical characterization of a surface. The BRDF is a measure of the amount of light incident from one direction that is scattered by a surface in another direction. This talk introduces the concept of BRDF and presents the thesis research of graduate student, Deepali Shirsekar, to investigate the BRDF of black coating, Aeroglaze Z302. Work includes design and fabrication of a high-accuracy bidirectional reflectometer and its use to measure the bidirectional reflectance of a black absorber Aeroglaze Z302®. A BRDF model consisting of diffuse, glossy, and specular components is fitted to the experimental results. Finally, the Monte Carlo ray-trace (MCRT) method is used to simulate the performance of any optical instrument which has Z302 material coated on its active surfaces. 

Organizer: Vinh Nguyen

September 28

Friday 4:00pm
304 Robeson Hall
(poster)

Faculty Meeting (No CSB Discussion Meeting)

Organizer: Vinh Nguyen

October 2018
October 5

Friday 4:00pm
304 Robeson Hall
(poster)

Nazia Munir (Mechanical Engineering)

"Investigation of the Gold-Black Absorption Mechanism"

The material called gold-black is an absorptive material frequently used in various thermo-detector. The advantages of gold-black that make it preferable over the other absorptive material is that it has the absorptivity almost one (α=1) in the visible and infrared range which means that it absorbs all the radiation incident on it and appears black in an observer’s eye. For this unique property gold-black has been used in thermal detector such as in micro-bolometer. The micro-bolometer converts the incident radiation to an electrical signal. Gold-black is used as a coating on the micro-bolometer to ensure a 100% absorption of the radiation. Micro-bolometer with gold-black coating has several applications specially in various program of Earth Radiation Budget where the global warming is closely monitored with satellite having micro-bolometer attached on it. The purpose of this effort is to establish a model of gold-black so that it can be used more efficiently in various detector. We seek a first-principle model for predicting the spectral absorptivity of gold-black. Gold-black has been widely used in various thermal and optical applications for more than a century. In most relevant contributions to the literature, gold-black is treated as a homogeneous layer whose behavior is governed by its bulk optical properties. However, on the microscopic level gold-black more closely resembles a fuzzy layer of moss or a miniature forest. This suggests that the optical behavior of gold-black can be better characterized by taking into account its actual morphology. We propose to model a layer of vacuum-deposited gold-black as a “fractal forest” where each branch of each tree is isolated and considered as an individual building block. In this treatment each individual branch acts as a dipole antenna with the forest as a whole behaving as a random-fractal antenna array. The approach of the current effort is to develop a model for the conversion of incident electromagnetic (EM) radiation to sensible heat by an individual branch behaving as a lossy antenna. The output of such a model would be the energy conversion efficiency (absorptivity), corresponding to a given wavelength, of a single branch having a specified length, diameter, and orientation with respect to incident EM radiation. The overall absorptivity of the forest at that wavelength would then be based on the statistical description of the spatial and angular distributions of branches of various length and diameter. The required statistical rules would be derived from microscopic study of actual gold-black layers.

Organizer: Vinh Nguyen

October 12

Friday 4:00pm
304 Robeson Hall
(poster)

Faculty Meeting (No CSB Discussion Meeting)

Organizer: Vinh Nguyen

October 19

Friday 4:00pm
304 Robeson Hall
(poster)

"Fall Break" (No CSB Discussion Meeting)

Organizer: Vinh Nguyen

October 26

Friday 4:00pm
304 Robeson Hall
(poster)

Harrison Wood (Biomedical Engineering and Mechanics)

“A study on the effects of in-plane swelling gradients on orthotropic plates”

In this study, we examine the effects of in-plane swelling gradients on resulting shapes of thin, orthotropic plates. Emphasis is placed on understanding how different swelling gradients and orthotropic material properties result in different shapes. This talk focuses on introducing the topic of incompatible elasticity applied to programming swelling functions and shapes in plates, and summarizes the current research of graduate student Harrison Wood on swelling and warping of engineered wood products. Several surface parameterizations are explored to explain warped shapes of orthotropic plates. An energy expression based on mid-plane strains and curvatures is minimized with respect to surface parameters, and competition between stretching and bending energy terms is studied to determine equilibrium shapes. Using some simple toy models of plate warp as inspiration, some scaling arguments are being developed to validate certain behaviors and shapes, such as the case where a specific in-plane swelling gradient results in a cylindrical-like shape at equilibrium for an orthotropic plate.

Organizer:Vinh Nguyen

November 2018
November 2

Friday 4:00pm
304 Robeson Hall
(poster)

Prof. Michael Flatte (University of Iowa)

Meeting with Students

Organizer: Giti Khodaparast

November 9

Friday 4:00pm
304 Robeson Hall
(poster)

Prof. William Ducker (Chemical Engineering)

"Absorption at Confined Interfaces"

Thin liquid films have different properties than bulk solutions because of the effects of the fields extending from the boundaries. These altered properties are important in determining the stability of colloid and nano-particle suspensions, wetting films, adsorption in confined spaces, and in the fabrication and application of nanoscale devices. Our interest is in adsorption, which affects many of these applications: there is a multitude of applications where surfactants, polymers, ions, etc. are adsorbed to effect changes in thin films, for exam-ple, to alter the stability of colloidal particles. We describe measurements of adsorption between two flat plates when the plates are separated by 0 – 65 nm and several results for several examples: depletion of a simple ion in dilute solution and adsorption in very concentrated salt solutions. These measurements have been made possible by our development of new tech-nique. Measurement of all separations is achieved simultaneously by measuring visible-light interference in a wedge-shaped crack created between an oxidized-silicon wafer and a glass wafer. The adsorbed amount is measured from the fluorescence emission of a dye, after accounting for the optical interference. The specific measurement is of the depletion of a divalent anion, fluorescein, in aqueous solution between two anionic solids. For dilute solutions at large separations between the flat plates, the dye is depleted rela-tive to the bulk concentration. At smaller separations, the depletion of the dye decreases. The range of the depletion and the magnitude of depletion decrease with shorter Debye-length. Both of these effects are con-sistent with a simple calculation using the Poisson-Boltzmann equation. For concentrated solutions, results do not agree with Poisson-Boltzmann theory. That theory predicts that the surface potential decays exponential-ly with a decay length (Debye-length) that decreases with increasing concentration. Results are consistent with an increase in decay length with increasing concentration. We make comparisons to results in ionic liq-uids and drawn conclusions for crystal growth through particle attachment. We

Organizer: Vinh Nguyen

November 16

Friday 4:00pm
304 Robeson Hall
(poster)

Faculty Meeting (No CSB Discussion Meeting)

Organizer: Vinh Nguyen

November 23

Friday 4:00pm
304 Robeson Hall
(poster)

Thanksgiving Break (No CSB Discussion Meeting)

Organizer: Vinh Nguyen

November 30

Friday 4:00pm
304 Robeson Hall
(poster)

Michael Kane (Mechanical Engineering)

"Topography and Mechanical Properties of Nanostructured PNIPAM Films"

PNIPAM is a thermo-responsive polymer that has wide applications in biological applications, including its use as a cell growth scaffold. In this talk, we will discuss some of the recent measurements that we have done on PNIPAM films on nanostructured substrates. Using Atomic Force Microscopy, we investigate the surface topography of the films at different temperatures as well as their mechanical properties in different parts of the sample. 

Organizer: Rana Ashkar

December 2018
December 7

Friday 4:00pm
304 Robeson Hall
(poster)

First Day of Exams (No CSB Discussion Meetings)

Organizer: Vinh Nguyen

Center for Soft Matter and Biological Physics Friday Discussion Meetings

Spring 2019

Organizer: Vinh Nguyen

These meetings occur on Fridays from 4:00pm to 5:00pm in Robeson 304 (unless otherwise indicated)

January 2018
January 4

Friday 4:00pm
304 Robeson Hall
(poster)

"No CSB Discussion Meeting Scheduled"

Organizer: Vinh Nguyen

January 11

Friday 4:00pm
304 Robeson Hall
(poster)

"No CSB Discussion Meeting Scheduled"

Organizer: Vinh Nguyen

January 18

Friday 4:00pm
304 Robeson Hall
(poster)

"No CSB Discussion Meeting Scheduled"

Organizer: Vinh Nguyen

January 25

Friday 4:00pm
304 Robeson Hall
(poster)

"No CSB Discussion Meeting Scheduled"

Organizer: Vinh Nguyen

February 2018
February 1

Friday 4:00pm
304 Robeson Hall
(poster)

"No CSB Discussion Meeting Scheduled"

Organizer: Vinh Nguyen

February 8

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

February 15

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

February 22

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

March 2019
March 1

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

March 8

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

March 9

Saturday 4:00pm
304 Robeson Hall
(poster)

"Spring Break"

Organizer: Vinh Nguyen

March 15

Friday 4:00pm
304 Robeson Hall
(poster)

"Spring Break continuing ends March 17"

Organizer: Vinh Nguyen

March 22

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

March 29

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

April 2019
April 5

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

April 12

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

April 19

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

April 26

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

May 2019
May 3

Friday 4:00pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

May 8

Wednesday 4:00pm
304 Robeson Hall
(poster)

Classes end


(No CSB Discussion Meeting)

Organizer: Vinh Nguyen

May 10

Friday 4:00pm
304 Robeson Hall
(poster)

Exams Begin


(No CSB Discussion Meeting)

Organizer: Vinh Nguyen

May 17

Friday 4:00pm
304 Robeson Hall
(poster)

University Commencement and College and Department Ceremonies


(No CSB Discussion Meeting)

Organizer: Vinh Nguyen

Center for Soft Matter and Biological Physics Friday Discussion Meetings

Summer 2019

Organizer: Vinh Nguyen

These meetings occur on Fridays from 1:30pm to 2:30pm in Robeson 304 (unless otherwise indicated)

May 2019
May 28

Tuesday 1:30pm
304 Robeson Hall
(poster)

Summer Session I 2019 Classes Begin


Organizer: Vinh Nguyen

June 2019
June 7

Friday 1:30pm
304 Robeson Hall
(poster)

Organizer: Vinh Nguyen

June 14

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

June 21

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

June 28

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

July 2019
July 5

Friday 1:30pm
304 Robeson Hall
(poster)

Summer Session I Classes End

.


Organizer: Vinh Nguyen

July 9

Tuesday 1:30pm
304 Robeson Hall
(poster)

Summer Session II Classes Begin

 


Organizer: Vinh Nguyen

July 12

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

July 19

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

July 26

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

August 2019
August 2

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

August 9

Friday 1:30pm
304 Robeson Hall
(poster)


Organizer: Vinh Nguyen

August 15

Thursday 1:30pm
304 Robeson Hall
(poster)

Classes End for Summer Session II


Organizer: Vinh Nguyen

August 16

Friday 1:30pm
304 Robeson Hall
(poster)

Exams Begin for Summer Session II


Organizer: Vinh Nguyen