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Fluorescent Chemosensors for Chloride in Water – Sensors and Actuators B: Chemical
A new publication is now available in which we calculated the binding properties of a fluorescent water-soluble chemosensor for halides which is specially sensitive for chloride. Once again, we were working in collaboration with an experimental group who is currently involved in developing all kinds of sustainable chemosensors.
The electronic structure of the chromophore was calculated at the M06-2X/6-311++G(d,p) level of theory under the SMD solvation model (water) at various pH levels which was achieved simply by changing the protonation and charges upon the ligand. Wiberg bond indexes from the Natural Population Analysis showed strong interactions between the chloride ion and the chromophore. Also, Fukui indexes were calculated in order to find the most probable binding sites. A very interesting feature of this compound is its ability to form a cavity without being a macrocycle! I deem it a cavity because of the intramolecular interactions which prevent the entrance of solvent molecules but that can be reversibly disrupted for the inclusion of an anion. In the figure below you can observe the remarkable quenching effect chloride has on the anion.
A quick look to the Frontier Molecular Orbitals (FMO’s) show that the chloride anion acts as an electron donor to the sensor.
Frontier Molecular Orbitals
If you are interested in more details please check: Bazany-Rodríguez, I. J., Martínez-Otero, D., Barroso-Flores, J., Yatsimirsky, A. K., & Dorazco-González, A. (2015). Sensitive water-soluble fluorescent chemosensor for chloride based on a bisquinolinium pyridine-dicarboxamide compound. Sensors and Actuators B: Chemical, 221, 1348–1355. http://doi.org/10.1016/j.snb.2015.07.031
Thanks to Dr. Alejandro Dorazco from CCIQS for asking me to join him in this project which currently includes some other join ventures in the realm of molecular recognition.
Symposium at IQ-UNAM 2015
Earlier this week we had at our annual symposium at the institute of chemistry where we had distinguished international visitors such as Prof. Theodor Agapie, Prof. Lanny Liebeskind (associate editor of Organometallics), Prof. Marc Petit and Prof. Francois Gabbaï (associate editor of Organometallics), as well as our very own colleagues like Dr. Fernando Cortés who presented a recent paper published on Nucleic Acids Research, and Vojtech Jancik who talked about the high resolution crystallography performed at CCIQS. One of the presentations I liked the most was the one by Dr. Abel Moreno who is now doing some research on the proteins that crystallize calcium carbonate in the formation of egg-shells; Dr. Moreno recently got some 70 million years old fossilized dinosaur egg-shells, from which he is expecting to isolate some samples! Very exciting! I visited Dr. Moreno’s lab to take a look at this fossils and forgot to take a picture of them but trust me they were very cool to look at.
Our lab contributed with a poster by ´Maru´Sandoval (pictures below) in which she presented her research on the excited states of bacteriochlorophyll molecules present in the Fenna-Matthews-Olsen (FMO) complex of photosynthetic bacteria, and more importantly on the excitonic transference between them with the use of the singlet fission model.
These are great opportunities to establish collaborations and get new ideas for future work. Kudos to the organizers and administrative staff for keeping the academic life of our institute to high standards!
New paper in JPC-A
As we approach to the end of another year, and with that the time where my office becomes covered with post-it notes so as to find my way back into work after the holidays, we celebrate another paper published! This time at the Journal of Physical Chemistry A as a follow up to this other paper published last year on JPC-C. Back then we reported the development of a selective sensor for Hg(II); this sensor consisted on 1-amino-8-naphthol-3,6-disulphonic acid (H-Acid) covalently bound to a modified silica SBA-15 surface. H-Acid is fluorescent and we took advantage of the fact that, when in the presence of Hg(II) in aqueous media, its fluorescence is quenched but not with other ions, even with closely related ions such as Zn(II) and Cd(II). In this new report we delve into the electronic reasons behind the quenching process by calculating the most important electronic transitions with the framework laid by the Time Dependent Density Functional Theory (TD-DFT) at the PBE0/cc-pVQZ level of theory (we also included an electron core potential on the heavy metal atoms in order to decrease the time of each calculation). One of the things I personally liked about this work is the combination of different techniques that were used to assess the photochemical phenomenon at hand; some of those techniques included calculation of various bond orders (Mayer, Fuzzy, Wiberg, delocalization indexes), time dependent DFT and charge transfer delocalizations. Although we calculated all these various different descriptors to account for changes in the electronic structure of the ligand which lead to the fluorescence quenching, only delocalization indexes as calculated with QTAIM were used to draw conclusion, while the rest are collected in the SI section.
Thanks a lot to my good friend and collaborator Dr. Pezhman Zarabadi-Poor for all his work, interest and insight into the rationalization of this phenomenon. This is our second paper published together. By the way, if any of you readers is aware of a way to finance a postdoc stay for Pezhman here at our lab, please send us a message because right now funding is scarce and we’d love to keep bringing you many more interesting papers.
For our research group this was the fourth paper published during 2014. We can only hope (and work hard) to have at least five next year without compromising their quality. I’m setting the goal to be 6 papers; we’ll see in a year if we delivered or not.
I’d like to also take this opportunity to thank all the readers of this little blog of mine for your visits and your live demonstrations of appreciation at various local and global meetings such as the ACS meeting in San Francisco and WATOC14 in Chile, it means a lot to me to know that the things I write are read; if I were to make any New Year’s resolutions it would be to reply quicker to questions posted because if you took the time to write I should take the time to reply.
I wish you all the best for 2015 in and out of the lab!
Summer Interns 2014
Just as last year, the “Dolphin Summer Internship Program” (Programa Delfín) has started and this time it coincided with #RealTimeChem week. Four students from various cities (and accents) around Mexico have come to our lab in Toluca in order to spend about 7 weeks of research in the field of molecular modeling and within our research of molecular recognition in biochemistry. Karen, Cynthia, Jesús and Marco have started their training today as they arrived to CCIQS so we went over the (very) basics of quantum chemistry, the (very) basics of Linux and the basics of Gaussian09. (I should really think about developing some web tutorials or something because this impromptu training is very exhausting!)
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- Left to right: Karen Díaz, Cynthia González, Marco Linares and Jesús Beltrán
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- Left to right: Karen Díaz, Cynthia González, Marco Linares and Jesús Beltrán
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- My overweight self – Interns in the background
Their academic backgrounds are mostly centered around pharmaceutics and biochemistry although their ages range from the second to the fourth year of college education. Computational chemistry is pretty unknown to all of them; I’ll do my best to change that, while at the same time I make them aware of its power as a research tool and as a research field in itself.
Here is to a very productive summer! I hope we manage to get enough data for a paper and, more importantly, that they all get a good experience out of their time here, make new friends and learn something new that enriches their skills in this increasingly competitive world.
Visit to ‘Universidad de la Cañada’ in Oaxaca, Mexico
A couple of weeks ago I was invited to give a talk to a small university in southern Mexico called ‘Universidad de la Cañada‘ in the state of Oaxaca, one of the most underprivileged states in our nation. This institution is a rather small one but the work they are doing over there with as little resources as they have is truly remarkable . UNCA offers degrees in pharmacy, pharmacology, food sciences, clinical chemistry and other topics that aim to supply the needed human resources for the various industries that are settled in the region. There is a true feeling of togetherness at UNCA since they have little pieces of equipment yet they are all fully shared among researchers regardless of who received the finance to acquire them. Last year, two of their students came for a two months stay, after which, Alberto and Eduardo got their names on a publication of our research group. It was nice to see them again and even nicer to learn they are about to finish their studies and that they will come back again to our lab in late July.
Every year at UNCA there is a Pharmacology Day on which the students show the results to their research projects during a poster session and listen to lectures by guest speakers from various universities around Mexico. Most of their projects were aimed to the isolation of natural products from local resources and their usage in several kinds of consumer products. UNCA is in a very small town, village I might say, surrounded by mountains and vegetation; the view was spectacular as you may see from the pictures below. Thank you very much to my good friend Dr. Carmen Hernández-Galindo for inviting me to participate and share our work with their students, I hope we may go back again and keep a fruitful exchange between our groups.
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- UNCA
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- Me, Eduardo, Alberto
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- Some arachnids
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- Dr. Carmen Hernández and I
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- Grasshoppers. A delicacy in Oaxaca
During this talk, I took the opportunity to talk about the aforementioned paper in the context of molecular recognition and their in silico design but I think I should have talked more about the computational strategies that are most employed in the pharmaceutical industry. Never mind. I hope I get the opportunity to right this wrong. Still it was nice to give Alberto and Eduardo the opportunity to brag a little about being published authors.
Kudos to Rola Aburto, Dr. Margarita Bernabé, Dr. Rocío Rosas, and all the academic staff at UNCA for their invaluable dedication to teaching science against all odds, I can testify, through the hard work of their students, hat their effort is paying off.
Taking the Joy of Chemistry into a Children’s Home
On Friday May 30th, my good friend Dr. Josefina Aldeco, my wife and I, visited a children’s home in Querétaro (central Mexico) and brought them a few cool chemistry experiments for a short show. This event was promoted by a non-profit organization called “Anímate a estudiar” (Dare to study), namely by Mrs. Paulina Milanés who is always looking for ways to encourage kids from poor backgrounds to pursue their goals through study; among other things, they provide backpacks with school supplies to orphan kids like the girls we visited.
As a way to inspire them, we handed each girl a balloon drawn in the shape of a brain and asked them to inflate them daily by reading; by doing their homework; by asking questions all the time; by working hard in pursuit of a brighter future for which their brains are the most powerful muscles.
Many reactions took place that Friday; not only inside the flasks and beakers before our little audience but also in their faces and their engagement with us. Little by little these girls got out of their shells and became more excited, up to the point of performing their own chemical reaction themselves by polymerizing some glue with borax in hot water. This was for sure the first time they got in contact with chemistry but the true goal was to set up a spark in their minds that one day may turn into a life opportunity. We are aware that one small chemistry show can’t really have that effect, but if many more scientists reach out to these kids there is a bigger chance of creating a ripple effect that convince disenfranchised children that studying is the way to take the wheel of their own future.
Science is about development; its about spreading knowledge and the love for knowledge. Although we most times sit high on our ivory towers it is paramount to remember that there is also a social component to the scientific activity. Kids are eager to learn, but most school systems do their very best to limit their curiosity and ambition. We hope these girls find in studying a way to a better, happier and safer future. Mexico has a large economic disparity; climbing the social ladder is very hard and even more so for women which makes these girls a very vulnerable social group in the next generation.
It only takes one day. One day and some potassium iodide; some mentos on a diet-coke (sorry, Gina, for the squirt!); some cobalt chloride on paper; some balloons some glue and some borax in hot water. But above all it takes a big commitment.
I hope you readers, computational and experimental chemists alike, take some time out of your busy schedules and share your passion for science with kids, specially those with the lowest opportunities of getting in touch with real scientists. You can also contribute to this noble effort by making a small pay-pal donation to www.animateaestudiar.org or to any other similar organization in your local community.
It only takes one day.
P.S. Thanks to Josefina from Universidad Autónoma de Querétaro for providing material and reagents. Please go and check out her blogs (here and here) and encourage her to write more often! (Did I mention she published in Science a few years ago?)
#RealTimeChem – Day 3
Welcome of the third installment of #RealTimeChem, the diary. As I did yesterday and the day before, I will summarize my day in chemistry throughout the Tweets sent over this event.
Sup. Info finished. Figs & tables will b ready today; on it. Off to a (video)conference by Dr. Marcos Hernandez @iquimicaunam #RealTimeChem
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
(Haha, I found the button to include the feed!)
I finally finished editing that supporting information I’ve been Twitting about all week, now I’m back at the manuscript re-editing a bit. This is a problem I have that I’m sure is shared by most of you: I just can’t let go. If I’m writing a manuscript I’ll read it and change it over and over; if I’m working on a presentation, I will edit and reorder the slides almost ad infinitum if it were not for deadlines. Professor Cea-Olivares, of whom I’ve written before in this blog, used to say that projects are never finished but merely abandoned. In all fairness we are still not on the ‘not letting go’ phase, there are still some sections of the manuscript that need our attention; and when I say we, I mean me and my collaborator Dr. Rodrigo Galindo who is currently working at the University of Utah (BTW go check out his blog and persuade him to pick it up again!)
But in the middle of the day there was a conference at Instituto de Química, in Mexico City, that I wanted to listen to. Dr. Marcos Hernández is a good colleague of mine who deals with asymmetric organocatalysis. I like his work a lot and I hold him in high esteem so I asked for a video transmission of his talk to be sent over to CCIQS at Toluca. In the following two Twits you can get a glimpse of our video conferencing facilities.
Me. At the videoconference hall #CCIQS waiting for @iquimicaunam #RealTimeChem twitter.com/joaquinbarroso…
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
And we are good to go! Live from Mexico City, is Dr Marcos Hernandez conf @iquimicaunam during #realtimechem twitter.com/joaquinbarroso…
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
Not all is work during RealTimeChem week, although perhaps it should be. Still, safety first! that’s our motto! (follow the link in message)
stock pic: important 2 remember: protect eyes & hands when u’re naked in a lab! twitter.yfrog.com/nymcyzp 4 those too excited by #RealTimeChem
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
Today I took some time to have a few interactions with other participants of #RealTimeChem and got to follow very interesting people. Definitely, after this week I will become a more active Twitter user (ouch!). But the research must go on, and today Maru started working on rendering the electrostatic potential surfaces for a rather large set of calix- and thiacalix[n]arenes for our line of research on molecular recognition agents.
#RealTimeChem Electrstatic potential surface of a calix4arene 1 down 119 to go 😉 twitter.com/joaquinbarroso…
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
#RealTimeChem same as before; top view; transparent surface. Which so u like better? Compchem yields nice pics too! twitter.com/joaquinbarroso…
— Joaquin Barroso (@joaquinbarroso) April 24, 2013
#RealTimeChem Another EPS (diff scale as in previous pic) twitter.com/joaquinbarroso…
— Joaquin Barroso (@joaquinbarroso) April 25, 2013
This is pretty much it for today; I’m very tired and I still need to work in other things so I’m off for now but stay tuned for more tomorrow when this blog will celebrate the 60th anniversary of the publication of DNA’s structure in Nature.
Cheerio!
#RealTimeChem – Day 2
This initiative has turned out to be a lot of fun for me! I think so far the thing that has captured my attention the most is to grasp the realization that science, chemistry in this case, is performed by humans in small, and sometimes not so confident, steps, a description far from the pristine one we daily read throughout the plethora of journals. A similar former initiative, which should have been brought back during this week, was the #OverlyHonestMethods one. It’d be a lot of fun to have both hastags together during an entire week. The other thing I knew, but that #RealTimeChem has helped me understand is the fact that a lot of resources for research are needed and getting said resources consumes a lot of our time as researchers: grant submissions; applications revisions; meetings; academic events and a long etcetera occupy our time and attention and this isn’t necessarily a good thing all the time.
So here it is; my second day reporting my #RealTimeChem
Joaquin Barroso @joaquinbarroso 7h
Supporting information for our paper feels endless now. I want to launch calculations & I still have a ton of emails to reply!
Supporting information for our most recent paper consists of more than 200 figures corresponding to a few conformations from several compounds; this has consumed a lot of my time but I’m finally done with it! Now, its only a matter of time for us to submit it -we are aiming high!- and hopefully this may happen during #RealTimeChem. That would be cool!
Joaquin Barroso @joaquinbarroso 7h
Reaching out during #RealTimeChem Any ECP/basis/functional recommended for La & Pr? http://bse.pnl.gov has 2 by Cao but no reference 
No reply, unfortunately. I need to run some calculations for a small collaboration and these compounds include either La or Pr; I need a, preferably relativistic or quasirelativistic) effective core potential (maybe I should write a post illustrating the difference between ECP’s and pseudopotentials) for these atoms that is also compatible with some relatively simple electron density functional. The Basis Set Exchange library has one by Cao but its not referenced so there is only so much I can do with it.
Joaquin Barroso @joaquinbarroso 7h
Watching all the wheels of chemistry turn (slowly) during #RealTimeChem makes you realize why each paper represents years of hard work
Between reading a Tweet about a grant submission and another one about having a paper published there is a lot of time and hard work involved, not to mention frustration, a little procrastination and a lot of fun over the course of a few years. During those years some chromatography columns are performed, some flasks are smashed and spectra are recorded. And this all happens very, very slowly as opposed as how we read it in journals where people seem to have had an original idea, gone to their labs, set up a few experiments, recorded the results and written the paper, and all before dinner!
The hindrances and intricacies of chemistry now have an outlet: blog-syn.blogspot.com In this site, the little details about synthesis are gathered in a sort of #OverlyHonestMethods way, only not as embarrassing; only practical. In a way, blog-syn is what this blog of mine was supposed to be for the lab of Dr. Silaghi-Dumitrescu back in Romania when I first conceived it. Little by little, the wheels of science turn but with every turn they move mankind forward.
Joaquin Barroso @joaquinbarroso 3h
An industrious student calculating electronic structure of host-guest systems #realtimechem pic.twitter.com/2QdF3vyBCa
Sadly, Maru is about to leave us for a short period of time now that she has completed her thesis and is about to get her B. Sc. in Chemistry; she threatens to come back for a Masters degree, though. She has played a crucial role in the lab’s success so I thought of taking a picture of her while working on her workstation. @RealTimeChem, the official Twitter account of the event, favorited this photo.
Joaquin Barroso @joaquinbarroso 1h
Valence bond theory class @comunidadUAEMex #RealTimeChem nice Slater determinants! 😉 pic.twitter.com/boOrB2IoCx
Tuesdays I teach a class titled ‘Molecular Design and Reactivity‘ (terrible name, I know) and today’s topic was the Valence-Bond method which, I’m sure you all know, is only of historical relevance although some nice conceptions arise from it, like the fact that a wavefunction can be approximated as a linear combination of smaller wavefunctions each corresponding to a specific electron configuration. I mostly use Donald McQuarrie‘s book on Quantum Chemistry, in case you are wondering.
This is a long three hours class starting at 5pm, and the research center is far from the chemistry school, so I usually don’t go back to the office afterwards. So here I am, at Starbucks in downtown Toluca, but chemistry for today is far from over! I still need to review some applications from students who are seeking funds from the local council for science to attend a seminar on polymers this summer in Barcelona. I was also requested by the Journal of Inclusion Phenomena and Macrocyclic Chemistry to serve as a reviewer for a submitted paper. Both activities have deadlines in May but I want to get them done now so I can brag include them in my #RealTimeChem productivity report.
A few hours later…
Joaquin Barroso @joaquinbarroso 3m
Just Finished reading two proposals, I’m going to accept them both! 2 kids going 2 intl polymer seminar #RealTimeChem
And so I did it! Two students from a private university in the state want to participate in a polymer seminar in Spain. I think they have impressive results; too bad I had to sign a disclosure agreement so I can’t write anything about their project. Good for them and good for COMECyT for sponsoring outstanding students in science and engineering!
These past two days I haven’t personally launched any calculations; I haven’t had time to read any journals nor to write any applications or papers, yet I’m certain that the wheels at our lab are slowly turning, hopefully forward.
#RealTimeChem 2013 – Day 1
The first day of the #RealTimeChem event has gone by and here I am blogging about it in order to participate in the ensuing #RealTimeChemCarnival which is the blogging section, so to speak, of the aforementioned event. So, without further ado, this was my #RealTimeChem day:
Disclaimer: I’m not much of a Twitter man myself so I apologize in advanced for any dumb or stupid usage of it. I’m also new to Instagram and Vine, which I only downloaded on account of this event. Sorry for not taking snippets from the Twitter feed but I’m on Windows7 starter here and I don’t have such tools; I’m also not going to download some tool right now, sorry for that but if you know a better way, please do share it! I will be posting all week long so it might come in handy.
Joaquín Barroso
Editing sup. info. new paper on electronic interactions in rotaxane-like molecules with bio applications. Hope #RealTimeChem brings me luck!
We are almost done with this paper on drug delivery systems based on the architecture of calix[n]arenes. We’ve found some pretty interesting results about which features suit better certain drugs both in gas and solution phases. Most of my day had to do with editing the supporting information. Below, the picture that acompanied the previous Tweet.
Today’s supporting info. +150 figures inserted into a Word file – I see rotaxanes!
Later on, along came a student whom, to be perfectly honest, I completely forgot about -my bad- but he was there and he was willing so off we went to work. Of course, being his first time, we had to start from scratch from the very basics of Gaussian’s use (and implicitly, the basics of the command line use in Linux). I’m not sure he wants his name to be posted here so he will remain in anonimity until otherwise stated. The associated Tweet read as follows:
Joaquin Barroso @joaquinbarroso 9h
1st Gaussian job 4 this new student #realtimechem http://instagram.com/p/Ya5oJbgQxk/
The new anonymous intern launching his very first Gaussian calculation – aww
and then,
Joaquin Barroso @joaquinbarroso 8h
Training a new student in using Gaussian, Gaussview and Linux. Lot of work to be done but he looks eager to learn 🙂 #RealTimeChem
Being so much into #RealTimeChem worked as a serious motivator; the more you published the more you wanted to keep going! So all day long I had my head filled with things that I wanted to do, but I made a strong case about twitting only those things that I actually did and nothing in the lines of ‘thinking of …’ or ‘wishing I could…’ that sort of thing. I usually take little notes on google calendars about my day’s work as a means to keep track of my productivity, or sometimes, sadly, my lack thereof. This time Twitter was a loud witness of my activities which, hopefully, may be considered productive.
I teach a class on electronic structure each Tuesday, so I started preparing my class for tomorrow as a kind of break from editing that supporting information; the Twit read:
Joaquin Barroso @joaquinbarroso 7h
Must not forget to prepare class 4 tomorrow. #realtimechem a new productivity tool! pic.twitter.com/7JFYuJ0FEJ
The book is “Quantum Chemistry” by Donald McQuarrie
Joaquin Barroso @joaquinbarroso 4h
All day editing sup. info. has rendered me cross-eyed! Time 4 a break. Will reply work (chem) related email 🙂 #RealTimeChem
and so I did. I got to reply to a professor in the far away island of Mauritius! He just invited me to participate in a virtual conference on computational chemistry. What a shame! It’d been nice to fly half way accross the world and set foot in that land! If you don’t know where Mauritius is, find Madagascar in southern Africa and then take a right on the Indic Ocean. As per his request, here I promote his event with all of you and with #RealTimeChem:
Joaquin Barroso @joaquinbarroso 3h
http://bit.ly/ZLre9V Virtual conference on comp. chem. in Mauritius. Please try the link. #RealTimeChem
Then more e-mail
Joaquin Barroso @joaquinbarroso 3h
#RealTimeChem just accepted invitation 2 virtual conf.; accepted new intern by mail; now reviewing 2 applications for conference stipends
I didn’t finish reviewing these kid’s work but I think they might get their plane tickets from the local council for science and technology.
As I wrote earlier, I’m not a Twitter man so I get easily overwelmed by all the information generated within. I wanted to go home but before I got to read some Tweets and I was astonished by the enormous ammount of messages in the lines of ‘submitted a grant, now when can I do the corresponding research?‘; ‘grading! what a torture!’ and some others that indicated people was doing administrative work when they really wanted to get their hands dirty in the lab. This was a surprise to me because I imagined that most Twitter users and therfore, #RealTimeChem participants would be young students who are the ones who actually are up to their necks in chemistry! of course I Tweeted about my little observation in two messages.
Joaquin Barroso @joaquinbarroso 2h
So interesting 2 notice #RealTimeChem deals more with research administration than wth research! I thought it’d be the other way around!
Joaquin Barroso @joaquinbarroso 2h
@RealTimeChem Is it measureable how much #RealTimeChem is chem. research & how much is adminstration/paperwork/grading? Might b interesting!
Dr. Joaquin Barroso's Blog 