TODAY

Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:           Thursday, 31^st May 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Jeff Hutter
Department of Physics & Astronomy
Western University

“Examining the role of crystallization inhibitors using atomic-force microscopy”

ABSTRACT

Kinetic inhibitors are additives that affect crystallization kinetics without altering thermodynamic properties, such as the melting point. Based on their effectiveness at exceedingly small concentrations, models for the mechanism by which such additives operate have assumed adsorption to crystal growth faces. A well-known model proposed in 1958 by Cabrera and Vermilyea (the C-V model) suggests that impurities adsorb to growth faces and pin growth steps, forcing them to curve, and thus decreasing the effective supersaturation via the Gibbs-Thomson effect. Despite considerable effort, direct evidence for this mechanism has only been offered for a few systems, while significant objections have been raised: How can the irreversible adsorption required to pin growth steps be reconciled with the observed dependence on inhibitor concentration? How can growth proceed at all in the presence of strongly adsorbed inhibitor molecules?

The main example of kinetic inhibition that will be discussed here involves the crystallization of calcium oxalate monohydrate (COM), which is the main mineral component of kidney stones. Certain proteins, such as osteopontin (OPN), are known to inhibit stone formation, but the details of the process are not well understood. In order to determine the role of such inhibitors, we have examined the growth of COM at the molecular level and in real time using the atomic force microscope (AFM). We find that the presence of OPN, as well as synthesized peptides corresponding to portions of the OPN molecule, results in clear changes in the morphology and propagation speed of growth steps. By observing the subsequent recovery of COM growth when the inhibitor is flushed from solution, we can test the validity of the assumptions of the C-V model. An improved understanding of this inhibitor mechanism may result in the design of therapeutic agents for the prevention of kidney stones, as well as an improved ability to tailor additives for a variety of commercial processes.

This message is sent on behalf of Dr. Jan Cami of the Department of Physics and Astronomy:

On behalf of the Department of Physics & Astronomy, it is my pleasure to cordially invite you to witness and observe the 2012 Transit of Venusthat will happen next Tuesday, June 5^th, from ~6 p.m. until sunset (see poster attached).

Transits of Venus are truly rare events: the phenomenon has only been observed six times since Johannes Kepler first predicted a transit to occur in 1631, and the next one will happen only 105 years from now—in 2117! It is one of the few events that give human beings a direct sense of the scale of the Solar System and, in fact, Venus transits have historically been used precisely to measure the distance scale of the Solar System.

The Department of Physics & Astronomy, the Centre for Planetary Science and Exploration (CPSX), and the Royal Astronomical Society of Canada (RASC) are working together to offer the public the best and safest observing experience. From about 5:30 p.m. onward, we will open up the Cronyn Observatoryand use the main telescope to project images of the Sun on a screen. In addition, we will have an observation station in the southeast corner of the Springett Parking Lotwhere we will offer diverse views of the event, including through a state-of-the-art solar telescope. At both sites, we will be distributing eclipse glasses that allow you to see the transit with your own eyes. A “planet walk” between the two sites will show a scale model of the Solar System, and in the conference room of the Cronyn Observatory, we will present a small exhibit about Venus and transits, as well as a live feed of the event as seen from different locations worldwide. Many professional astronomers will be around to answer any question you may have. After sunset, we will keep the observatory open for stargazing, which will include telescopic views of Mars, Saturn, and many more wonders of the Universe. In case of bad weather, the exhibit at the observatory will be open, and astronomers will give presentations about related topics.

It would be my pleasure and my honour to greet you and your family at this event, and share this unique and historical moment. Please do not hesitate to contact me for further information.

Sincerely,

Jan Cami

Cronyn Coordinator

Jan Cami                                                              e-mail : jcami@uwo.ca

Assistant Professor                                         Tel : +1 519 661 2111 ext. 80978

University of Western Ontario                   Fax : +1 519 661 2033

Department of Physics and Astronomy

Room 203 P&AB

London, Ontario N6A 3K7

CANADA

Venus Transit poster.pdf Download this file

Our PASA soccer team had an awesome start to the summer season, with a 4-1 victory over Michael Thwaites’!

Our next game is against Engineering UTD on Monday, June 4th at 6 PM at the soccer fields across from Health Science.  Come on out and bring some P&A spirit to cheer our team on!!!

Have you voted yet?  The Society of Graduate Students (SOGS) presidential elections are still open for voting today and tomorrow.  To vote, go to http://www.uwo.ca/sogs/ and click on “Click here for the online ballot” under the heading “Details of the Presidential Election”.  You will be asked to log in with your university email prefix and password (to ensure that you are a graduate student and that you do not vote more than once).  It takes seconds to do.

Here are some questions you may find yourself asking at the moment, along with answers.

I thought SOGS was just a bus pass and health plan, why does it need a president?
Yes, it is true that you get your health plan and bus pass through SOGS, however, they do much more.  SOGS also advocates on your behalf on university issues (such as Access Copyright and tuition costs), organizes events at the Grad Club and JLC (to mention a few places), and provides bursaries, scholarships, subsidies, and emergency loans to graduate students, among other things.

Why should I care?
The ancillary fees that you pay with tuition include a membership fee to SOGS.  Unless you don’t care where your money goes, you should probably care about this election.

Who should I vote for?
There are three candidates running for presidency (in alphabetical order according to last name):
          Geoffrey Bardwell
          Tom McMurrough
Chris Shirreff
Their one paged platforms are attached below in the same order as above.

SOGS sounds interesting, I want to know more or get involved!  How can I?
You can send either of your SOGS councillors, Mel or Neven, an email (my email is mwrigh58@uwo.ca) or come out to our next meeting–Thursday, May 31st 6 PM in NCB 114. 

Bardwell.pdf Download this file

It is that time of the year again … Canadian Cancer Society (CCS) Relay for Life event (Friday June 15th at the TD Waterhouse stadium).  This is the signature event that the CCS organizes as their major fundraising effort.  Funds raised in this event goes to prevention advocacies, support for those diagnosed and undergoing cancer treatments, and for research. With the drop in government support for cancer research, fundraising from relay for life is becoming ever more critical.

My students have created a “Physicist for Life” team (this is our fifth year, I think). This year, I am going by this motto: participation first, donation second.  Considering asking one of your friends and join this team together:   http://convio.cancer.ca/site/TR?team_id=269961&pg=team&fr_id=10563&fl=en_CA&et=WpCQGjlWopET_F0d0ssSDw&s_tafId=188868. In fact, I would be so happy if physics and astronomy can spin off another team.  If you have as much an inkling of interest, come and talk to me. If you wondered why I have not signed up yet, the reason is simple:  I am hoping to create another team.

The idea for us to participate is to close the circle: helping CCS help us researchers make discoveries to help patients.  Just by being there, participants and volunteers would appreciate it and will have an extra reason to continue to support CCS and its research arm. In addition, I have been critical of their allocation for research spending. The researchers’ voice can be heard louder and we can all be part of the solution if we contribute to helping CCS in their signature fundraising event.

Thank you.

Eugene

When Adam Farag got back from his conference in Australia, the two things he was most excited about were that, for one, an egg on a piece of bland toast could cost $12.50, and more importantly that evoTV was airing a  four part series giving a rare interview with the first man to set foot on the moon, Neil Armstrong.

So, thanks Adam on the great advice on where not to eat breakfast in Melbourne!

An Audience with Neil Armstrong

SpaceX has successfully docked the Dragon spacecraft with the International Space Station in a first for a commercial vehicle.  When do we go to Mars?

Our “Extrasolar Systems” science olympics event was expanded into an Astronomy Triathlon and incorporated into the Grade 9 Pentathlon in Thursday Science Olympics.  We went from 5-6 teams per year to 17!  Event organizer Allison Hill did an excellent job revising the event to take into account the new Ontario grade 9 astronomy curriculum.  Thanks are also due to Alex DeSouza, Tyler Desjardins, Robbie Halonen, Matt Abado, and Laura Lenkic for contributing to the planning and execution of the event.

The Department of Physics and Astronomy presented a hands-on display at SLOME 2012.  Winners in 2011, this year the display came away with an Honourable Mention award.

The intrepid group of volunteers were Matt Abado, William Choi, Peter Frank, Allison Hill, Cameron Hopkins, Viatrix Lee, Daniel Martire (shown in photo), Roger Odell, and Melanie Wright.