Biking with and for Art (Fovargue), our awesome lab manager!

  Thank You, dear Art, for everything, your help and support for over a decade, and all those beautiful memories like the ones we shared this morning biking all together! YOU WILL BE MISSED!

JMU Physics Majors doing research in Nuclear Physics attended the 13th Annual Colonial Academic Alliance Undergraduate Research Conference!

The Physics and Astronomy Department at JMU was represented by two physics majors - Wayne Morris (senior) and Evan Meekins (junior) - at the 13th Annual Colonial Academic Alliance Undergraduate Research Conference that took place at Drexel University (PA), March 27-29, 2015.

Both our physics majors did a great job showcasing their undergraduate research work: Wayne Morris (research advisers Drs. Ioana and Gabriel Niculescu) had a poster presentation entitled "Dark current, gain and wavelength testing of PMTs for the gas ring imaging Cherenkov detector" while Evan Meekins (research adviser Dr. Adriana Banu) had an oral presentation entitled "94Mo(g,n) cross section measurements towards understanding the origin of p-nuclei".

Kathleen Krist (Chemistry major), doing research in the field of materials science under mentorship of our own Dr. Christopher Hughes, also had a great oral presentation at this year's CAA Undergraduate Research Conference. The title of her presentation was "The utilization of chloroform post-treatment to improve the adhesion of Au thin film onto PMMA".

Wayne Morris (senior) during a poster session at the CAA 2015 Undergraduate Research Conference at Drexel University

Evan Meekins (junior) presenting at the CAA 2015 Undergraduate Research Conference at Drexel University

JMU was represented overall by a large delegation of 9 students (2 from Physics and Astronomy, 1 from Anthropology, Media Arts & Design, 1 from Biotechnology, 1 from Chemistry, 2 from Public Policy & Administration, 1 from History, and 1 from Biology). Dr. Marta Bechtel (Biotechnology) and Dr. Adriana Banu (Physics and Astronomy) served as the two chaperones of the delegation.

JMU delegation at the CAA 2015 Undergraduate Research Conference, Drexel University

We were very honored to have with us also Dr. A. Jerry Benson - JMU's Provost & Senior Vice President for Academic Affairs, who was very impressed with the performances of our Dukes:

Thanks to all of you for your stellar performance at the CAA Undergraduate Research Conference.  You were such great representatives of all the students at JMU and our university as a whole.  It was my pleasure to have a little bit of time to be with you.  Best of everything as you move toward the end of the semester.  And a special thanks to Drs. Bechtel and Banu for your caring leadership and mentoring.

A. Jerry Benson
Provost

JMU Physics Launches Bottle Rockets at Raw Learning in Staunton!

JMU Physics & Astronomy seniors Keely Criddle (left)
and Nicole Creange (right).

On Friday, March 20, two JMU Physics seniors -- Keely Criddle and Nicole Creange -- joined John C. Wells Planetarium Director Shanil Virani at Raw Learning in Staunton bright and early! Ok, it wasn't so bright, as there was a persistent drizzle of cold rain, but it definitely was early. Nevertheless, the order of business this morning was to construct bottle rockets using 1L bottle (or 1.5L or even a 2L!), cardboard, construction paper, and LOTS of duct tape! Our fuel was frozen CO2 (aka "dry ice") and water! 

Raw Learning is a private school/homeschool learning resource center located on the campus of the Virginia School for the Deaf and Blind. Many of their students were eager to participate in this engineering exercise and learn what variables affect spaceflight (mass, aerodynamics, amount of water, dry ice, etc). 

Here are some of their designs!

Of course, once constructed, we now need to launch these bottle rockets! The videos are in SLOW-MOTION so you get the full effect of the tension at mission control as they wondered how their design would fare!

          

JMU Students at a National Conference! - The APS March Meeting

The week before Spring Break, eight JMU students had the opportunity to present their research in San Antonio, TX at the APS March meeting. Coming from the labs of several professors with a variety of research interests, these students either gave talks or presented posters of their research projects. From the lab of Klebert Feitosa there was Keely Criddle (yours truly) and Seth Heerschap. From the lab of Jason Haraldsen there was Nikki Creange, Brock Crook, Greg Houchins, and Galen Richard. From the lab of Chris Hughes there was Kathleen Krist. And from the lab of Brian Utter there was George Wilkes. Below are pictures of these students (in the order the are listed above) as well as the title and abstracts of the projects they presented. Unfortunately there is no picture of George Wilkes, so beside his abstract you will find a picture of the exhibit hall in which his poster was hung.

Mechanical Properties of Hydrogel Beads

Fragile solids made of dense disordered packing of bubbles, droplets, and grains are able to withstand small stresses by virtue of system-wide force chains that lock the system into a jammed state.  The nature of the jamming transition in such soft materials has been the subject of intense research, but despite much effort, a deep understanding remains elusive. In this experiment we study the mechanical properties of hydrogel beads to exploit them as force transducers in densely packed systems. The experiment consists of applying uniaxial planar compressions on the beads and correlating the force to the bead’s strain and contact area.  The results show that while the strain scales linearly with the radius of the contact area, the force and strain are found to obey a  power law relation with a range of exponents from 1.9 to 2.7. This result leads to a power law dependence of the force on the contact area radius of the compressed beads of similar size. ​

 Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants 

The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

Understanding the optical and electronic properties of Ga-doped graphene

We simulate the optical and electrical responses in gallium-doped graphene, using density functional theory with a local density approximation. We show the effects of impurity doping (0-3.91\%) in the graphene sheet and for each doping percentage the change in electron density, refractive index, and optical conductivity are reported. Here, gallium atoms are placed randomly (using a 5-point average) throughout a 128-atom sheet of graphene. These calculations demonstrate the effects of hole doping due to direct atomic substitution, where we find a disruption in the electron density for small doping levels, which is due to impurity scattering of the electrons. However, there seems to be a doping percentage, above which we have calculated, at which the system transitions to produce metallic or semi-metallic behavior. These calculations are compared to a purely theoretical 100\% Ga sheet for comparison of conductivity. Furthermore, we examine the change in the electronic band structure and density of states, where the introduction of gallium electronic bands produces a shift in the electron bands and dissolves the characteristic Dirac cone within graphene.

Determination of superexchange correlations in magnetically substituted graphene

 We investigate the electronic and magnetic properties between two homogeneous magnetic impurities (vanadium, chromium, or manganese) in a 128-atom graphene superlattice. With varying the impurity distance, we calculate these properties using a first principles approach. For each configuration, we determine the electronic bandstructure and density of states, along with the Mullikan populations for each atom. Furthermore, we calculate the exchange parameter between the two magnetic ions through the analysis of the change in total energy for different magnetic configurations. We found that the magnetic impurities induce a mangetic moment in the graphene superlattice, helping to meditate the superexchange between the impurities. Depending on the choice of ion used, the interactions between the two ions can exhibit either a ferromagnetic or an antiferromagnetic behavior. These correlations indicate an RKKY-like behavior in the system.

Generalization of Magnetic Dimer Excitations

Magnetic dimers commonly appear in the study of molecular magnets and quantum dots. Here, we discuss analytical representations for the inelastic neutron scattering excitation cross sections and static structure factor for the general S1S2 dimeric system. Employing generalized Pauli matrices and the Kronecker tensor product to construct the matrix representation of the spin Heisenberg spin-spin Hamiltonian. After using exact diagonalization to determine the eigenstates of the spin Hamiltonian, we formulated an analytical solution to find the structure factor coefficients used in determining the inelastic neutron scattering excitation cross section from both the ground state and first excited state. We also detail a method for finding the Sz polarization constant within an applied field that may represent the presence of an external magnetic field. Furthermore, we provide a sample set of data and intensity plot generated from our results to illustrate experimental representations for split energy levels.

Variational calculations for spin canting at ferromagnetic/antiferromagnetic 

interfaces

Understanding the complex interaction between materials is critical for the development of spintronic and electronic devices in the technology industry. In this report, we examine the canting of local moments throughout a ferromagnetic/antiferromagnetic heterostructure, where a combination of interlayer mixing and orbital reconstruction can be described as a local exchange field at the interface. Using a variational method and semi-classical approach, we examine the canting of spins throughout the full multilayer heterostructure. We approximate the interlayer interactions as an effective field throughout the interface and apply a standard spin Hamiltonian with spin anisotropy for the intralayer interactions of the ferromagnetic and antiferromagnetic layers. Overall, we show that observed finite magnetization and rotation of the local moment observed in LSMO/BFO is due to the interface interactions. Furthermore, we predict a size limit for this effect in the antiferromagnetic (BFO) layer.

The Utilization of Chloroform Post-Treatment to Improve the Adhesion of Au Thin Films onto PMMA

The metallization of Au onto plastics is an important processing step in the fabrication of microfluidic devices. While its corrosion resistance and excellent electrical and thermal conductivity make Au a good choice, its inertness results in poor adhesion to polymer surfaces. Previous studies have indicated that exposing commercially available Poly(methyl methacrylate) (PMMA) sheets to chloroform vapor following Au deposition significantly improves adhesion. In this study, we deposited 6 nm of Au onto 1.50 mm thick PMMA and exposed the samples to vapor released from chloroform heated on a hot plate set at 70 ∘C. The force required to remove the Au thin films was determined by placing samples on a polisher spinning at 150 rpm and utilizing UV-VIS spectroscopy to measure the transmittance of 700 nm light through the films to quantify their removal as a function of applied polishing force. The Au thin films were also characterized using AFM. AFM images demonstrated a progressive roughening of the surface corresponding to an increase in applied force. Additionally, these images support a model in which the chloroform treatment softens the PMMA surface, producing a softened layer that the polisher removes simultaneously with the Au thin film.

Granular gas mediated attraction of intruders in a granular Casimir effect

When two objects are submerged in a granular gas, entropic effects due to inelastic collisions lead to attractions between the objects. This has been referred to as an analog to the Casimir effect, though arises via a different mechanism. In this experiment, we place two objects (such as vertical plates or spheres) in either a strongly driven granular gas or dense fluid. We find that when the plates are closely spaced, there is a net attractive force. By analyzing high-speed video, we track the distance between these plates and characterize the effective force versus distance with changes in the vibration parameters and initial separation. A 2D simulation is also used to further explore parameter space.

-Keely Criddle

JMU Physics & Astronomy Blogger

Demystifying the Expert: Brycelyn Boardman

From Left to Right: Hosts Feitosa and Constatin, Dr. Brycelyn Boardman,
Mikhail, Shelby, Alan, and Abigail

On Thursday, February 26, JMuse Café's Demystifying the Expert series came to a close with our last expert of the year, Dr. Brycelyn Boardman from JMU's Chemistry department. For those of you who tuning in to these events (several months late, unfortunately), this series, brought to you by JMuse Café and our hosts from the JMU Physics department, aims to bridge the gap between scientists and the community through informal, educational, and often times humorous means. This series, inspired by Boston NPR show You're the Expert, consists of two hosts (Dr. Anca Constantin and Dr. Klebert Feitosa), and a panel of improv comedians from JMU's only improv group New & Improv.'d. With the help of the hosts, the panelists (Abigail, Alan, Shelby, and Mikhail) had to figure out exactly what Boardman's expertise is before the evening came to a close. 

Brycelyn Boardman has been at JMU as a faculty member since 2011. She was a student at JMU (and even still has the same JMU email address!), where she pursued her undergraduate degree before attending the University of California at Santa Barbara where she earned her Ph.D. in Chemistry. Before returning to JMU she did a postdoc at Columbia University.  

In the first round of games the panelists were allowed to ask only yes/no questions regarding Boardman's work. During this time they were able to get to the root of her project: trying to make new material for better solar panels. Solar panels are expensive and very stiff because they are comprised of inorganic materials. Although it is possible to make solar panels out of organic materials, they do not work as well as the expensive inorganic ones. The purpose of Boardman's work is to use a hybrid of organic and inorganic materials to make the best solar panel possible, or as she put it, "to make my Ph.D. advisor proud." 

Our Wonderful Audience Members!

Her work can be difficult for many reasons. Some of the compounds she works with, like tin, can be fatal to swallow, inhale, or even absorb through the skin. Both inorganic and organic materials can be quite difficult to synthesize and the two do not want to stick together. When one panelists asked how she gets them to stick together if they don't like each other we were all introduced to Boardman's baby hands. No, they are not actual hands from actual babies - however the term appropriately describes the mechanism (and it's silly to imagine Boardman ordering buckets upon buckets of baby hands for her research).  Essentially she forces these baby hands (the organic part) onto beach balls (the inorganic part), much like an adapter. The baby hands hold hands with each other, and the hybrid material is made. One of the panelists asked Boardman how realistic it would be for solar energy to be our only source of energy. Unfortunately, the cost holds us back from achieving that currently. Boardman informed the audience that while we currently pay around a penny per Watt, solar energy costs around a quarter a Watt. This aside, she informed us that if all the open land in the Midwest could provide enough energy to fuel the whole world. 

All of these events were recorded for those of you unfortunate enough to not attend!

Overall, the night was full of comedy and informal science education. Dr. Constantin did not hold back with her onslaught of cheesy chemistry jokes; I'm fairly certain she'd been preparing all evening for that one moment. As sad as we are to see this year's series come to a close, it was great to have a strong finish with Dr. Boardman and the panelists from New & Improv.'d.

-Keely Criddle

JMuse Café/ JMU Physics & Astronomy Blogger

"Our Island Universe" Debuts on WMRA!

OUR ISLAND UNIVERSE debuts tomorrow on WMRA Public Radio! John C. Wells Planetarium Director Shanil Virani will be your host every week for a 90-second look at new discoveries in our understanding of the cosmos and what it means to us here on Earth. 

Podcasts of every show will be available from WMRA's website. The first podcast is already available for your streaming pleasure!

Our Island Universe is a collaboration between James Madison University's John C. Wells Planetarium and WMRA. Weekly segments will air Friday's during NPR's Morning Edition and in the afternoon during Science Friday!

2015 Saturday Morning Physics at JMU came and went...

Kudos to Geary Albright, Art Fovargue, the physics faculty lecturers, the physics majors, and last but not least our dear participants (students, teachers and parents) who contributed to yet another great edition of the program! Well done everybody! So long!

See photos here from the wrap up event today, Feb. 28, 2015!

Demystifying the Expert: Jason Rosenhouse

From left to right: Feitosa, Constantin, Rosenhouse, and panelists
photo from breezejmu.org

On Thursday, January 29, 2015 the third installment of JMuse Café's series, Demystifying the Expert, took place. Through teaming up with physics professors Anca Constantin and Klebert Feitosa to present this series, JMuse Café  has been able to close the gap between scientists and the JMU public. This is done through back-and-forth guessing, joking, and discussion of the expert's expertise between our hosts (Constantin & Feitosa), the expert, and 4 members of JMU's only improv comedy group New & Improv.'d. As I mentioned in the post about the most recent event, the format for this series was borrowed from a Boston NPR show entitled You're the Expert.

Our expert this event was Jason Rosenhouse, a professor of Mathematics at JMU. As one of the hosts aptly pointed out at the beginning of the show, JMuse Café could easily run at least 4 events focused on Rosenhouse (further speculation has led me to believe that 4 events may still not be enough, considering his potential for both engaging and entertaining the public); unfortunately, we only had one. Before coming to JMU in 2003, he spent three years at Kansas State University after earning his Ph.D. in Mathematics from Dartmouth and his B.S. from Brown. In addition to a number of publications pertaining to his research, Rosenhouse has authored 3 award-winning books (all of which found their way into my Amazon shopping cart while I wrote this...).

Before giving away too much about our expert, it's important to acknowledge the panel of comedians whose job it was that evening to try to extract that information from him. Trevor Knickerbocker is a senior intelligence analysis major, currently enrolled in one of Dr. Feitosa's classes. Despite this, he still maintained that Feitosa didn't feed him any information about the expert. Amanda Anzalone is a junior media arts & design major double-minoring in  French and creative writing. She may have gotten answers wrong, but at least she could do so in two languages. Business major Mikail Faalasi came to this series with his knowledge of science limited to the science of making money. Lastly, Logan Brown is a junior theater major whose answers were both comedy (for the audience) and tragedy (for him).

Our Panelists, from left to right: Mikhail, Amanda, Logan, and Trevor
photo from breezejmu.org

Following the same outline as previous events in the series, the evening consisted of several games with time for discussion in between. To jumpstart an evening consisting primarily of the expert getting bombarded with questions, Rosenhouse was given the opportunity to ask the panelists a question: What is mathematics? While the panelists were technically correct in saying that math is "NUMBERS", "and some letters", "and some imaginary things", the correct answer was in fact, "a chick magnet."

In the first game, the panelists are given the opportunity to bombard the expert with 20-questions-style questions. During this time, the audience was able to gain long lists of things Rosenhouse does and does not do. On the former list are things like, theoretical math, getting cramps from writing theoretical math, graphs, solving equations, spending time inside, and escaping life. Of the latter, we learned that Rosenhouse does not apply his math to a "field" of study, because, as he mentioned earlier, he does not go outside.

What really sparked Rosenhouse's interest in math was a day in 6th grade when he was faced with the first theorem that was not obviously true to him: the Pythagorean theorem. He remarked that his teacher at the time just threw it up on the board without proving it, and this both impressed him and caused some skepticism. It was then that he saw that math is more than what most people think it is.

At this point, Rosenhouse surely made math-lovers out of anyone in the audience who was not one already; he pointed out that people who say they don't like math, simply don't like arithmetic, but the subject itself is,

    A combination of art and science and beauty - it's the exact opposite of memorizing rules - it's discovering them and proving them.

He went on to comment that people who think that math is fundamentally about calculating things have missed the point entirely; it's about observing the beauty of math. For mathematicians, the fact that math is useful is simply a bonus on top of everything else math is. Rosenhouse commented, "We can make money and go back to our little enclaves to do math!"


Throughout the evening, there were brief discussions of the three books Rosenhouse has authored. The first book he discussed was The Monty Hall Problem: The Remarkable Story of Math's Most Contentious Brain Teaser. The Monty Hall problem was inspired by a game show where contestants are faced with 3 doors, one of which has a prize behind it. After choosing one door, the host (aware of what lies behind each door) opens one of the doors that does not contain the prize, giving the contestant the opportunity to change his or her guess now that the odds of guessing correctly have changed. The "problem" behind the Monty Hall problem, is whether or not being able to change guesses actually makes a difference. In addition to the mathematical implications of the problem, there are also psychological aspects of it as well. Secondly, Rosenhouse discussed a book he co-authored with Laura Taalman, another professor of Math at JMU: Taking Sudoku Seriously: The Math Behind the World's Most Popular Pencil Puzzle. This book addresses the questions mathematicians have about sudoku puzzles (which,  contrary to popular belief, do require math to solve - just not arithmetic). On a topic not wholly unrelated to math, his third book, entitled Among the Creationists: Dispatches from the Anti-Evolutionist Front Line. On this topic, Rosenhouse said,

            The evolution debate is where scientific ignorance has consequences – the earth isn’t 6,000 years old. These people don’t know what they’re talking about. They reference math and science and they whip out equations, but if you know anything, you know they’re wrong. Yet, they’ll say it with confidence. You have extreme insularity – that’s the problem. People will tell them what they want to hear as if it validates their opinions.

Throughout the following games, the audience and panelists gained further insight into the specific work Rosenhouse does concerning Kayley graphs, sexy primes, and the Cheeger constant. They also got to know a lot about the expert as a person. His favorite plant is the rhododendron, and he may well be the only person who thinks clowns are funny, not creepy.  But beyond that, he quite possibly one of the most quotable people we've seen in this series. When asked what he believed the meaning of life to be, he promptly replied,

    Find something you enjoy doing and leave your little corner of the world better for having done so.

As evidenced by last Thursday's evening of comedy and mathematical discussion, it is obvious that he certainly has accomplished that and probably more. If you were unable to attend this past event (as well as the two before that) you have truly missed out. But there is still one more chance, so be sure to join us in the flex space of Rose Library at 6:30 pm on February 26, 2015 as we bring this series to a close!

Hosts Feitosa and Constantin with Rosenhouse and panelists in the background
photo from breezejmu.org

-Keely Criddle

JMuse Café/Physics & Astronomy Blogger

JMU PhysTEC in the news

JMU's PhysTEC program (Physics Teacher Education Coalition) and the role Learning Assistants in Physics 240-250 were recently highlighted on JMU's home page. See the complete story here: JMU addresses shortage of high school physics teachers

Photo of JMU Physics major Kerlin Doss who is in the Secondary Education track and has 

participated as an LA and is one of two student LAs highlighted in the article.