• Blog Stats

    • 54,386 hits
  • Archives

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 124 other followers

  • Copyright notice

    This blog entry and all other text on this blog is copyrighted, you are free to read it, discuss it with friends, co-workers and anyone else who will pay attention.

    If you want to cite this blog article or quote from it in a not for profit website or blog then please feel free to do so as long as you provide a link back to this blog article.

    If as a school teacher or university teacher you wish to use content from my blog for the education of students then you may do so as long as the teaching materials produced from my blogged writings are not distributed for profit to others. Also at University level I ask that you provide a link to my blog to the students.

    If you want to quote from this blog in an academic paper published in an academic journal then please contact me before you submit your paper to enable us to discuss the matter.

    If you wish to reuse my text in a way where you will be making a profit (however small) please contact me before you do so, and we can discuss the licensing of the content.

    If you want to contact me then please do so by e-mailing me at Chalmers University of Technology, I am quite easy to find there as I am the only person with the surname “foreman” working at Chalmers. An alternative method of contacting me is to leave a comment on a blog article. If you do not know which one to comment on then just pick one at random, please include your email in the comment so I can contact you.

Agatha Christie

Dear Reader,

It has come to my attention that some crime writers have been giving out instructions and tips on how to commit crimes in their novels. For example I discovered to my horror that Agatha Christie was trained as a chemist and that she wrote some books which had clear misuse potential. The problem is that if the plot of a book explains to a would be murderer how to commit murder then it would provide the non expert with new ideas of how to commit this vile crime.

I would like to suggest that crime authors should in the interests of public safety not give out information which is of obvious use to evil doers. For example if a book was to be published in which it explains how to make a silencer for a firearm then the book could make it much more easy for someone to commit murder with a gun and get away with it. While I am not in favour of spoiling people’s fun through censorship I think it is reasonable that some information should not be circulated in a form which the general public can search or read with ease.

Urea formaldehyde

Dear Reader,

I was reading my copy of the vintage chemistry handbook and I noticed that it has a method for making a urea/formaldehyde resin. I am well aware of the fact that formaldehyde is a harmful substance and that some products made from condensation polymers made from it tend to release formaldehyde into the air. So I considered the question of what other aldehydes could be used.

I noticed quickly that glyoxal has been used as an alternative to formaldehyde, I find it an interesting idea as glyoxal is a very toxic aldehyde which is able to cross link biomolecules. Glyoxal can be used to kill germs. Here is a patent on the subject of these plastics. I hope to be able to write some more on the subject of this class of materials soon.

Is the internet making students less honest

Dear Reader,

Recently in the Times Higher Education a paper was reviewed which considers in a serious manner the hypothesis that “students cheat more because of the existence of the internet”. This paper was reviewed by Jack Grove.

Regarding Jack Grove’s review of David Ison’s paper in the Journal of Academic Ethics. I feel that the headline of “Older papers had higher similarity index than the more recent ones” is rather misleading. When I read David’s paper I found that the difference between the similarity indexes of the newer and older dissertations was far smaller than the standard deviation in the values. To me this indicates that todays PhD students are neither better or worse than the older students. The fact that the standard deviation on both numbers was about 60 % of the mean values suggests to me that the degree of similarity is subject to considerable variation between students.

The incidence of the extreme incidents of plagiarism (Simindex > 40 %) in Dr Ison’s paper are small in number, only three such events exist in his data set. Using the statistical idea (Poisson) used commonly in radioactive decay counting (SD = N1/2, Standard deviation = square root of number of events observed). This count of 3 events with a SD of 1.7 is not a good measurement of the incidence of such extreme plagiarism events. A 16 % chance exists that fewer than 0.7 % of dissertations fall into this shocking class, equally a 16 % chance exists that more than 2.6 % of dissertations fall into this class.

A classic method in radiometric work to improve the statistics is to increase the count number, I would like to suggest that the study be repeated with at least ten times as many dissertations. If this new data set includes 30 such documents then the SD on this measurement will be 5.5. Such an improved measurement would give us an additional insight into plagiarism. I would like to suggest that those dissertations with the high similarity indexes be examined in detail, firstly to rule out “false positives” and secondly in an attempt to reconstruct what the students did. I would also like for a study to be made of the incidence of plagiarism as a function of subject area.

I think that while the existence of web pages has made it more easy to cheat, the existence of the internet also makes it much more easy to catch a cheat. Some years ago someone I know had a student who cheated in a literature review assignment by copying the text of someone else. It was very easy to spot this vile misconduct, the student’s style of writing suddenly changed for the better. The style of the student changed from that of a typical student into that of a very polished and experienced academic. The problem was proving the cheating had occurred, the academic had to search high and low for the source article. In the end the academic found it, but now days automated tools such as “Turnitin” will find it very quickly for you. Some years ago I tested one such tool by writing a text full of total random nonsense with the occasional sentence taken from another source dropped in. I used things like obscure bible verses (these were found), UN reports and other even more exotic documents. The search tool within 24 hours had given me a list of the URLs of all of the sources I used for this test of the system.

My advice to students is “do not try to cheat by copying text off the internet”, it is a form of cheating which I think is rather silly. People who cheat in this way are very easy to catch.

Oliver Sacks RIP

Dear Reader,

It has come to my attention that Oliver Sacks MD has passed away, he was an interesting character one which you could either love or hate. Maybe even both.

In the defense of Sacks I would like to point out that I have read several of his books and I will admit that when I wanted to understand myself better that several of his books were on my reading list. I will admit that I did take something positive away from reading his books.

Old chemistry book

Dear Reader,

Some of you will be aware of the fact that I have recently purchased a copy of a 1940s home chemistry manual, while I was sorely disappointed that it is not the one which I recall from my youth which explains how to make chloroform and use aniline, it does have some rather interesting chemistry.

For example it has a chapter on polymer chemistry which explains how to make the crosslinked urea formaldehyde resin, on the subject of how to use formaldehyde in a safe manner it suggests “hold your breath” at one key high risk moment. I have to say that this is not exactly in agreement with the ideas which my safety officer at work would quite rightly recommend to me.

If I do try to react formaldehyde (methanal) with urea I will use a fumehood, I would like to suggest that my readers take similar care with formaldehyde.

A slight disappointment

Dear Reader,

I have recently obtained a 1940s handbook of chemistry aimed at teenaged children, this book is rather more lively than many later books on home chemistry. But it is not quite the one which I read as a youth which had even more extreme experiments.

The book which I now have in front of me is “Chemistry Experiments at home for boys and girls” by H.L. Heys, this book has an interesting array of experiments but it does not have the super outlandish ones.

I will write about the content of the book by Heys soon, but if any of my readers know of a home chemistry book which has experiments using aniline, the synthesis of chloroform from acetone and the synthesis of benzene from benzoic acid then please inform me of the title, author and other details of the book.

Calcium carbide IV ?

Dear Reader,

I think that I might be losing count of the number of posts on calcium carbide but here are some of the pictures of the solid. One common form of the compound is the tetragonal form which can be thought of as being like a cube, except the cube has been compressed or stretched on one edge to make a less symmetric box. Here is a view of one unit cell, I have added a couple of carbon atoms in near by cells to show the anions in all their glory.

Tetragonal calcium carbide unit cell

Tetragonal calcium carbide unit cell

Now that is not the end of the story, other forms of calcium carbide exist. For example there is a cubic high temperature form. This solid has disordered anions, without disorder it would have an impossible formula of CaC8. Here is a picture of the unit cell for you to look at.

Cubic calcium carbide

Cubic calcium carbide

Now we are not going to stop here, there are at least two more solid state forms of calcium carbide. Here is the monoclinic form, how monoclinic does not mean a single place where a doctor, dentist or vet works. Instead is it a type of unit cell, in a monoclinic cell one of the angles is not a right angle. Now for your delight here is a picture of the cell.

You should be able to see that it has the anions and calciums, the anions and calciums form chains. Here are the calcium ions and the anions.

Monoclinic calcium carbide only the bonds in the carbide anions are shown

Monoclinic calcium carbide only the bonds in the carbide anions are shown

Now we add the bonds to show the chains in the solid.

Monoclinic calcium carbide with the metal carbon bonds which form the chains

Monoclinic calcium carbide with the metal carbon bonds which form the chains

Now we add the bonds which interlink the chains.

Monoclinic calcium carbide with some of the bonds which link the chains together.

Monoclinic calcium carbide with some of the bonds which link the chains together.

Some other views of the monoclinic compound will be shown soon.


Get every new post delivered to your Inbox.

Join 124 other followers

%d bloggers like this: