By Christopher Moore
My student and I are still working hard on our scanning tunneling microscope. We’ve had some issues with the solder-less breadboard we were using to prototype. Stuff was shorting on the breadboard, so we placed the components on a proto-board and soldered them together.
The pre-amp is now working exactly like it should. We supply a low current via a make-shift current source measured using a picoammeter and read correct voltage values on the other side. We’ve simulated the pre-amp using MultiSim and our circuit is behaving like the simulation.
The difference amplifier is another story! We’re still troubleshooting that, since it isn’t doing anything like what it should. With a +5 V signal and a set-point of +3 V, we should get a +2 V output. We get something different, though the something does scale correctly with variations in the set-point.
The scanner control electronics are working fine. They always have.
Over the next few weeks we expect to have all of the electronics properly placed on proto-boards, tested and functioning as they should. We have to go back and build a new approach mechanism for two reasons:
(1) The quasi-kinematic approach using machine screws is TERRIBLE! I have a micro-positioner thingy I salvaged from the junk heap that we plan on using for the fine approach. The coarse approach will still be made via machine screws. We’re also going to make the stage and lever much bigger. An STM that can fit in a pocket is no longer a goal — we’d rather have one that works!
(2) If you look back at the pictures of our piezo scanner, you’ll notice relatively large gauge wires and solder. I think the wires are too stiff, too thick and offer too much resistance. Also, it is possible that we’ve de-poled our piezo, though I’ve soldered piezo-electric ceramic before with fantastic results. We’re going to build the new scanner with smaller gauge wire and silver paste.
Concerning the piezo: I have a student using a Michelson interferometer to measure the piezo displacement with voltage for calibration purposes, and to convince myself that I haven’t de-poled the ceramic.
The department is purchasing licenses for LabVIEW and I have ordered some data acquisition boards. Once we’re done troubleshooting the STM via the oscilloscope, then the next student I can cajole into working on this project will be developing LabVIEW code to control the set-point, gains, and sample bias and pick-off the x,y,z voltages and convert them into pretty pictures. If we get really ambition, then maybe we’ll design an all digital feedback STM. That will require much faster DAQs, though, taking the project out of the couple-of-hundred-dollars range.
By Christopher Moore
I have been missing for a long time.
Last year I was busy writing and defending a dissertation. Then I got a new job. I’ve moved, had a baby and started a new career in the span of six months. Hopefully you understand my absence.
However, the long neglect of ilovephysics.com is officially over. I am starting a new column called “Ask a Physicsist.” Click on the graphic at the top of the page to learn more. Essentially, I’m going to start answering your emails! I get several a week from Physics Phans and crackpots and others, and I thought I would make my responses a little more … ummm … well … I’m actually going to start responding. However, I’m going to respond via this public forum so that everyone can benefit from my wisdom 
.
Also, two students will be coming on board as contributors to this site. I’m kind of forcing them to contribute, since I control their grade!
Donny will be blogging about the STM project that he is working on. And Andy will begin blogging about a vacuum sputtering system that he will be building this semester. Look for their contributions in the next week or so.
So I’m back. Let’s hope I’m better at finding time to write this semester.
By Christopher Moore
I am a scanning tunneling microscope (STM) guy. I completed my M.S. thesis using a commercial instrument and I have always wanted to build one. Until recently, I haven’t had the time or the money. About 1 month ago, a student here at Longwood University approached me about doing a project. The first thing that came to my mind was “Let’s build an STM!” The student agreed, and off we went. Now building an STM is part of my job!
Commercial research STM systems cost up to $250k or more. Less powerful “student” systems run around $15,000 but offer little to the researcher. The STM that my student Donald and I are building will end up costing ~$100 in parts. More important, the parts can be found at the local hardware store or ordered online.
Over the next few months Donald and I will chronicle the construction of our STM, showing you what parts we have used, how we are constructing it, and how it works. We plan to have a fully-functional analog STM up and running by the end of this semester (early December 2007). Next semester begining in January, we will chronicle the build of our second STM which will be digitally controlled via a computer. The budget for our computer controlled model is less than $200, and the microprocessor and control board are being designed by an undergraduate at Virginia Commonwealth University.
We have already begun. To learn more about STM, this specific project, or current progress, and what’s next, continue reading.
(more…)
By Christopher Moore
Here is an interesting article about biofuels posted at Functionalism In Action by Ian Conrad:
There is so much hype, today, about biofuels. They are seen as the savior of our nation — especially corn-ethanol; especially if one were to compare the subsidization that goes on here. But is this the right approach?
The article continues, making the following point with regards to a new process af turning corn sugar into good old fashioned gasoline:
To compare, the most effective gallon-per-acre biofuel crop right now is palm oil, which hovers around 680 gallons-per-acre. So this is more than triple the amount — and it’s good ol’ fashioned gasoline to boot! Here comes the number crunching. In 2004, the US used approximately 318 billion gallons of oil. At 2,000 gallons per acre, that comes out to roughly 159 million acres of arable land — and this is assuming that the cellulosic starch problem can be overcome — for which there are no hypothetical solutions yet available. According to the CIA’s “World Factbook”, the US has 9,161,923 square kilometers of land, 18.01% of which are arable. That’s 1,650,62 square kilometers. 1 acre = 0.00404685642 square kilometers, so the US has 407,739,281 acres of arable land. To maintain the energy usage levels of 2004 purely from biofuels derived from this process would require ~40% of all arable land in the nation.
The question Ian asks is an important one, considering a slew of would be presidents are busy interupting the breakfasts of Iowans: “What the devil is the justification of the subsidization of corn-ethanol production?”
Read the entire article here.
By Christopher Moore
I was almost fooled by a Nigerian scam. The method used is actually interesting and shows how sophisticated scammers have become. I post this here to alert others in a position similar to mine. The summary: if you receive an unsolicited email asking for you to send some item to Africa, then RUN, RUN, RUN away.
Last month, I received the following email:
Dear Mr Chris,
I am very glad for your effeorts on your website.
I am a Head of Science Department in a high school and I need your guidiance on how I can get Video cassetes and CDs in Sciences (Physics, Chemistry, Biology, Mathematics and Geography) that covers High School syllabus to back up the teachers efforts in the school.
I would be obliged if I can be refered to or assisted in this regards.
My best regard
Dr. George Robinson
H.O.D Sciences
First, I receive these types of emails a few times a month. Generally they come from students but every now and then I get an email from a high school or college teacher. Initially, I thought nothing of the request. However, a few key markers in the email should have tipped me off:
1) Why would the head of a science department at a high school who holds a doctorate have such a terrible grasp of the English language? I assumed “Dr. Robinson” was at a school in the UK, since he was using a UK Yahoo account, which brings us to …
2) Why would he send the request via Yahoo instead of via a school account? And …
3) Why in the world would he be incapable of finding this information on his own. Afterall, he supposedly has a Ph.D. and enough sense to be promoted to the head of a science department.
Anyway, I was in a generous mood. I send the following reply:
Hello George.
I’m sorry to get back to you so late.
I’m afraid I can really only help you with materials for physics.
Paul Hewitt has a really good series of videos:
http://www.arborsci.com/SearchResult.aspx?CategoryID=20
I also highly recommend his Conceptual Physics textbook for conceptual courses at the high school level.
Some really good video demonstrations can be found online for free. Specifically, Colorado State University has a good collection:
http://www.engr.colostate.edu/~dga/video_demos/
The Wonders of Physics is a good series by Clint Sprott:
http://sprott.physics.wisc.edu/wop.htm
We are currently developing our own video series for ilovephysics.com, though this project will take about a year.
I would like to point out that out of the three recommendations, two were completely free and available online. This will be important in a minute. Usually, with these types of unsolicited requests my initial response is sufficient for the person doing the requesting. However, over 1 month later I receive the following email:
Dear Mr James, (notice I went from Mr Chris to Mr James)
I have visited the sites recommended to me by you, I am finding it a bit difficult to communicate with them because they have not been responding to series of e-mail sent to the customer care services of their organization. his is neccessary so that I can arrange a money transfer for the payment of the DVDs since I am not residing in the United States and credit card payment is not really reliable from africa countries.
I will like you to please rescue me from this predicament by getting me new or used DVDs in Physics, Chemistry, biology and Mathematics. Please send the bill via e-mail and how I can made that will get to you either through western union or any other way you might prefer. Please help select those you feel deem fit for high school student and maybe earlier part of their university programm. I will also enquire about the cost of shipping by DHL or any other Courier services and include the cash with the payment if you assist me on this.
I need this Dvds to back-up the teachers in their lessons.
I will be obliged if this can be done to assist me.
hank you for your anticipated cooperation.
Dr. G. Robinson
If the red flags weren’t a wavin’ after the first email, they sure as hell were after this one. In the first sentence, “Dr. Robinson” tells me that he could not communicate with the providers. First, I provided three links in my email. Two of those links were to sites that offered completely free online videos. Just for fun, I called Arbor Scientific about the Hewitt videos at their number posted on their contact page. I was speaking with someone within moments.
The second sentence lets me know that “Dr. Robinson” is not from the UK as I thought, but resides in an African country. Again, why would he be using a UK Yahoo account? Why would his school’s credit card be un-reliable? African countries (specifically, Nigeria) are hotbeds for fraud rings. US companies are leery of sending items to these countries without firm payment beforehand. However, credit card payments are the best means of payment in these situations.
And here comes the scam. The rest of the email asks ME to purchase the videos (notice he did not specify which videos), have them shipped to him in Africa, and he will pay me via some easily fraudulent method (such as Western Union). I’ve done sales on E-Bay, so I know that YOU NEVER accepts payment via Western Union from someone you do not know. If you do, you never ship anything until the payment clears. Oh, and you never ship anything to an African country, especially if they want to pay via Western Union.
The hard part is figuring out how he intends on making enough money off of me to make the scam worthwhile. The DVDs would be a few hundred dollars that, at best, he could sell for half their retail cost. My guess is that had I continued, more pieces of the scam would have come out.
Even if I wasn’t sure that this was the set-up for a scam, I wouldn’t do it. If some random physics teacher in Boise, Idaho emailed me asking about such a transaction I would refuse. In fact, I would find the request highly inappropriate from someone who should know better. Young physics students who I have never met ask me for all manner of things via email. But they do not know any better. A grown man with a supposed Ph.D. that heads the science department at a high school should know better.
After this email, I realized I was probably the target of a scam. Of course, “Dr. Robinson” could be real, so I simply responded via email that I found the request highly inappropriate. I received the following response within an hour:
Dear Mr James,
Thank you for your response, I actually got a response today (now precisely).
I believe I could also get more educational materials from you also been an educationalist like me. That is why I decided to also contact you for assistance and I will like to make payment with the method I feel I can rely on and will get to you also. I do not have access to international credit card, hence my decision to seek for your assistance in this regard. And I believe you can help since you are the USA and it will be easier to make purchases within US as I understand.
If the need arrises I will give you a call
Best Regards
Dr. R. George
Now I KNOW that “Dr. Robinson” (or is it Dr. George?) does not exist and that I am the target of a scam. We’ll see if he calls. That should be fun.
The moral of the story: If someone in Africa that you do not know asks you to buy them something, then RUN, RUN, RUN.
By Christopher Moore
Epsori Space Systems announced today that its Free Seeds Experiment will be flying aboard the Up Aerospace SL-2 launch, scheduled for Saturday, April 28 th 2007 . Epsori Space Systems will distribute the experiment to 2500 classrooms in the fall of 2007. The payload contains 22 ounces of mixed vegetable seeds. Teachers in grades 3-5 will be offered a free experiment along with approved curriculum, student workbooks, and packages of seeds that have flown into space. The experiment allows students to compare the growth of seeds in a control group, to the growth of the space seeds. Students are taught classic techniques of scientific observation and record keeping during the experiment’s two week execution.
Epsori Space Systems executives believe its pioneering approach of flying experiments to space to teach fundamental science skills in the classroom provides a fun way to connect children with space science. Quoting Jerry Hilburn, founder of Epsori Space Systems:
By placing seeds which have flown into space in the hands of our children, we engage their minds, excite their hearts, and make science fun!
Teachers are encouraged to visit the site to learn more about the experiment. Epsori is now accepting applications from teachers for the free program.
Epsori Space Systems was founded in 2007 with the mission of delivering affordable space based experiments to classrooms across America . Based in the heart of the New Space industry in Southern California , Epsori plans to launch thousands of experiments onboard emerging New Space commercial spacecraft in coming years. Up Aerospace is the first “public access to space” company to provide a low cost method of placing our experiments in space. Quoting co-founder, Joshua Johnson, “We are excited to be onboard SL-2 and look forward to flying payloads with Up Aerospace for many years to come”. Epsori Space Systems will launch a new social network website for teachers and students in September, which will provide a platform for reporting experiences, research findings, classroom photography, and video content of the experiments execution. Distribution of the seeds experiment will begin September 1st , 2007 .
The Epsori Space Systems media team will attend the launch in New Mexico on Saturday, April 28th, to record videos of the event and interviews of key participants. All news, photos, and videos will be posted at www.epsori.com and ilovephysics.com will provide coverage, as well.
By Christopher Moore
I’ve decided to participate in the OneBillionBulbs project and have begun replacing my old incandescent light bulbs with energy-saving fluorescent bulbs. I encourage everyone else to join the ilovephysics.com group and begin saving money and energy.
The graphic will remain on the right side of the page.
Hat tip: Kn@ppster and Glen Reynolds.
By Christopher Moore
Like every other Virginian, I am literally numb. More than 32 innocent people lost their lives today on the campus of Virgina Tech. If you live in Virginia, then chances are you know someone who either attends or works at the University, and chances are you have been paralyzed by today’s senseless violence. I have former students who go there, and I pray they are alright. I have colleagues who work at the school, and I pray they are alright. And of course, I pray that the 27,000 others are alright, though I know that is not the case for those 32.
Although I am currently a VCU Ram and in August I will be a Longwood Lancer, I am a Hokie today.
We are all Hokies today.
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