Obituary Egon Matijevic (27 April 1922 – 20 July 2016)

Appeared earlier in the IACIS Newsletter 63 of January 2017.

Egon Matijevic (right) with Ger Koper (left) and Dick Bedeaux (middle) in the bar during the International Workshop Particles and Surfaces: Fundamentals, Techniques and Applications held in Oud Poelgeest, near Leiden, NL, March 13-16, 1999.

The first time I learnt about Egon Matijevic was while studying the book on light scattering of small particles by Milton Kerker. In many places of the book, references to articles with Matijevic were made in particular where fine particles were discussed. The book as well as the methods to make standard particles by Matijevic were then – and probably still are – widely used in cytology, the study of cells, in particular connected to cancer research.
When I later turned to colloid science, my interest in the work of Matijevic grew again: he was the master in synthesizing particles of all kinds of composition, shapes and sizes. It was very clear that he made Potsdam, NY for a while the Colloid Center of the Universe. It is not for nothing that in this period he was president of the IACIS (1983-1985) and that the IACIS conference of 1985 was held in Potsdam, NY.
When I regularly visited Clarkson University in the late 90’s, Matijevic in his 70s was still very active at Clarkson University and it was very clear that he still played an important role in its leadership. He published 581 papers and held 17 patents. As a mentor, he instructed 15,000 undergraduate students and advised more than 50 PhD candidates, 50 MSc students, and 130 postdoctoral scholars. He delivered more than 70 plenary and keynote lectures at meetings and symposia in dozens of countries worldwide, including the prestigious Faraday Discourse at the Royal Institution in London.
Matijevic was a brilliant scholar whose prolific and inspired research helped to shape modern colloid and surface science. His techniques have found applications in products like the capacitors used in microelectronics, magnetic memories, and the ceramics used in electronic components. It is for this reason that we invited him in 1999 to our workshop on Particles and Surfaces: Fundamentals, Techniques and Applications (see above picture). The organization of the workshop required discussion leaders that were themselves adequately knowledgeable in the field of their session and Matijevic did not disappoint us!
59 years of service to Clarkson University, indeed their oldest and longest serving active, full-time faculty member, have now come to an end. Many like myself will cherish good memories of him despite his at times strong opinions and incredible drive. As IACIS we should be thankful for him taking the leadership as well as organizing an IACIS conference.

Ger Koper

little Hill and BIG Hill

Appeared earlier in the IACIS Newsletter 57 of September 2014.

Terell L. Hill (1917-2014)

On the 23rd of January, Terell Leslie Hill, a very productive scientist and a prolific writer, passed away at the age of 96 in Eugene, Oregon (USA). Many of us have been trained and used his An Introduction to Statistical Thermodynamics, often termed “little Hill”, and looked up the finer detail in Statistical Mechanics: Principles and Selected Applications, “Big Hill”. The younger generation will favor the Statistical Mechanics book by Donald A. McQuarrie, his student, which carries largely the same spirit. The most interesting aspect of this and other work of Terell Hill is that most of his scientific papers were subsequently published as text books, sometimes not much later than the originals appeared in print. It is particularly in this way that his work is much better known than that of contemporaries.

Nanothermodynamics

In 2001, Hill coined the term nanothermodynamics as a more fashionable version of the phrase that he used for his work on the Thermodynamics of Small Systems. Indeed, this touches our field, the thermodynamics and statistical mechanics of systems of colloidal particles, polymers, or macromolecules. Specifically, Hill stated: “This subject, which now might appropriately be called nanothermodynamics, was investigated at some length by the author in 1961-3.” (Nanoletters 1 (2001) 111-112).
Other books by Hill, all extremely relevant to our field, are on Free energy transduction, on Cooperativity Theory and on Linear Aggregation Theory. Importantly, all are affordably available through Dover Publications . Without doubt, these little books make Hill’s contribution to modern science BIG!

Ger Koper, NL editor.

The Vroman effect

Appeared earlier in the IACIS Newsletter 56 of April 2014.

Leo Vroman (1915-2014)

On the 22nd of February, Leo Vroman, a prolific poet mainly in Dutch and an illustrator, passed away at the age of 98 in Fort Worth (USA). In 1946, he published his first poems in the Netherlands, and since then has won almost every Dutch literary poetry prize possible. On poetryinternationalweb.net we find about him: Leo Vroman is the “grand old man” of Dutch poetry. He began writing poems well before World War Two and is still regarded as one of the most lively poets writing in Dutch. This liveliness has much to do with the form and tone of his work, at once loosely conversational and full of ingenious rhymes and playful neologisms.

So, a poet died … and a dutch one at that! Why should we care?

It is indeed not because of his poetry that Leo Vroman is remembered here. He was a scientist, a hematologist to be more precise, that discovered the now called Vroman effect which is exhibited by blood serum protein adsorption. The effect is, that proteins with the highest mobility, and not necessarily with the highest surface affinity, arrive first to the surface and adsorb. The slower proteins arrive later and replace the first-comers when they have a higher surface affinity. This does require some mobility of the already adsorbed proteins. The classical example is when fibrinogen displaces earlier adsorbed proteins on a biopolymer surface to be subsequently replaced by high molecular mass kininogen.
The topic has been studied for over 50 years by now and in 1992 a Festschrift appeared in honour of Vroman’s 75th birthday that was fully devoted to this. As of today scientists are investigating the effect. On the one hand, one tries to find a rationale for the behaviour and on the other hand there is the desire to obtain better control for biomaterial design and maintenance. What is maybe the most striking phenomenon is that protein adsorption is at least partially reversible; for synthetic polymers this is at times hard to achieve. But then, protein replacement is also far from trivial involving “tricks” like head on adsorption of the second to the first, turning around of the complex, and subsequent detachment of the first from the second that is now adsorbed at its bottom. It will be some time from now before such a trick will be performed by a synthetic molecule.
Leo Vroman himself called himself unbelievably lucky to observe the phenomenon and to do further research on it. His driving force was the development of blood-compatible materials, a topic that he followed until late in life. Even in 2009 he contributed a review where he enthusiastically reports on the development of live blood vessels. Indeed, he significantly contributed to his field but the effect is surely of interest to Colloid and Interface Scientists as well.

Ger Koper, NL editor.

“Nonsense, McBain”: a century of micelles

Appeared earlier in the IACIS Newsletter 50 of February 2013.

J.W. McBain (1882-1953)

It was one of these wonderful little COST CM1101 workshops, this one being on Malta the very beginning of this year, where Andreea Pasc from the Université de Lorraine told us that this year micelles are having their hundredth name day. The reference that was given, is a funny one as it does not pop-up when doing a typical literature search. It is actually pointing to a discussion following a lecture by Wolfgang Pauli from Vienna (!) on the viscosity of protein solutions in which James W. McBain indeed uses the term as an alternative to “colloidal ion”, the more common term in those days, in a short contribution entitled Mobility of Highly-charged Micelles.

While searching, one comes across the statement in the header. No doubt one of the present sources is the worthy website by Michael Blandamer of the University of Leicester that serves as a very reliable reference on applied thermodynamics. Fredric Menger’s 1979 review on the structure of micelles is what is mentioned as the source. According to these authors — and all “copycats” — it was made by “a leading physical chemist chairing the meeting” of the Royal Society of London. Of course, it would then be interesting to know who might have made such a bold remark. From the citation one finds that the authors got this information from McBain himself, who in 1926 wrote[1] the — to me — slightly different “… So novel was the finding that when in 1925 some of the evidence for it was presented to the Colloidal Committee for the Advancement of Science in London, it was dismissed by the Chairman, a leading international authority, with the words, “Nonsense, McBain. …” From where Fredric Menger, more than 50 years after McBain’s account, got his information is unclear but it remains to be seen whether the chairman indeed was a physical chemist. She could have been a physicist for that matter …

[1] in “Colloid Chemistry”, Vol. 5, J. Alexander, Ed., Reinhold, New York, 1926, p 102.

Ger Koper, Newsletter Editor

Where is Faraday’s gold?

Appeared earlier in the IACIS Newsletter 48 of October 2011.

While preparing a manuscript on high yield synthesis of uniform gold nanoparticles, a discussion on the stability time scale of colloidal dispersions developed in which it seemed appropriate to mention the world record in this: the more than 150 year stability of the gold sols prepared by Michael Faraday. In 1856 Faraday turned his attention to the interaction between light and matter after noticing that very thin films of gold kept the shiny yellow reflection but transmitted green light. He made numerous samples of colloidal gold of which he learned how to obtain the various colors as well as how to make them stable. In 1857 this work was described in the Bakerian lecture to the Royal Society. Many of these samples are lost but according to common knowledge, some of them remain in London.
For the manuscript at hand, a primary source was needed to refer to but whatever we could find; they were all – at best – secondary sources: information collected by others. One of the more explicit sources, the website of a well known manufacturer of colloid scientific equipment, mentions the Science Museum in London. Many other sites and documents do likewise.
After sending an electronic request to the conservator of the museum, the following answer was received “The situation is a little bit complex. Until 1999 we had a Faraday exhibit which displayed gold films deposited on watch glasses made by Faraday alongside a tall vessel containing colloidal gold (Zsigmondy’s method) which otherwise had nothing to do with Faraday.” The interesting consequence of this statement by the conservator of the Science Museum could be that there are quite a few false statements about and very likely even pictures of vessels not older than a few years instead of the 155 as claimed!
A further message from the conservator of the Science Museum reveals that some gold sols, of which pictures circulate the internet, could be in the Royal Institution (Ri), also in London. The confirmation came from the Curator of Collections who stated that “They are on permanent display within the Michael Faraday Museum area of the Ri, on the lower ground floor of the building, within the only section of Faraday’s original laboratory that still exists.” In addition, pictures were sent of which one accompanies this article and demonstrates the Tyndall effect that betrays colloidal dispersions.
In conclusion, the gold sols made by Faraday are indeed in London but not in the often mentioned Science museum but in the museum of the Royal Institution. We are happy to have spent some time finding out the truth about these gold sols and not to have merely repeated a false statement.

Ger Koper

 

Lekkage (2)

De rubber slab is inmiddels binnen en die kan er morgen wel op. De lekkage is waarschijnlijk dan maar ten dele verholpen. Het lood aan de achterkant maskeert het een beetje, maar aan die kant is het zink goed hoog opgetrokken. Als het hoog komt stort het aan de voorkant over. Echter daar is wel een probleem.

De overlappende zinken platen lijken niet aan elkaar gesoldeerd. Als het water omhoog komt op het dak kruipt het daardoor naar binnen in plaats van er over heen over te storten. Daar moet nog wat op gevonden worden!

 

Lekkage

Wat is het probleem? Eind vorig jaar hebben we de voordeur laten vervangen en na het een goed half jaar aan te kijken is daarna het halletje weer gefatsoeneerd. Helaas, na de heftige stormen van afgelopen weken bleek er wat gelekt te hebben.

Er stond me bij dat de monteurs na het plaatsen van de voordeur meldden dat ze een luchtsleufje boven de deur hadden overgelaten dus nu het mooi weer was maar eens de sierbalk boven de voordeur weggehaald en die afdekplaat nader bekeken. Inderdaad hadden ze een flinke sleuf overgelaten. In feite stond de hele afdekplaat bol.

Eerst de dekplaat maar eens losgehaald. Het was duidelijk dat aan de binnenkant water had gelopen, dus we waren op de goede weg.

Echter, de binnenkant was niet zo aangetast. Afgezien van de onderkant die gelekt had naar binnen toe.

Bovendien bleek de afdekplaat nauwelijks meer dan een millimeter over de bovenkant van het kozijn van de voordeur te vallen. Dus maar een nieuwe afdekplaat gemaakt zodat de overlap ongeveer anderhalve centimeter werd en goed aan alle kanten afdichtte.


Verder heb ik EPDM rubberfolie besteld om er over heen te laten vallen en onder het zink van het dak te laten beginnen zodat eventueel overstortend hemelwater over de dekplaat heen wordt geholpen. Daarna kan de sierbalk er weer overheen.

WebPi: Web server and reverse proxy

For WebPi, the computer that would become responsible for the connection between my local area network and the world wide internet, an RPi3 was chosen. The idea was to install a renowned web server software package on it, Apache.

The first step is installing the operating system, Raspbian. Since the machine would run without console, the light version should be sufficient. Any missing packages can be added anyhow. At the time of writing, the latest version is Stretch. That proved not to be fully stable yet for the subsequent steps, so I chose the previous version Jessie (2017-04-10). Installation runs smoothly and after changing the host name, allowing SSH and setting the time zone the machine is ready for use. Important issue is here to set a new password for the standard user, pi, otherwise the vulnerability of the web site and subsequently the whole local area network will be at stake.

There are quite a few descriptions available on the internet to install Apache, I chose the one that was clearly aimed at the kind of RPi I was using: “How to Make a Raspberry Pi Webserver” by Alok Naushad. It is intended for RPi2 but appears to work as well for the RPi3 with Jessie Lite. All steps were followed until setting a static IP-address. In my router, a Fritz!Box 7581, there is no need for that, as it has a primitive DNS for the connections within the LAN, e.g. WebPi.fritz.box . This will keep track of a correct IP-address. The router also has the option to fix the IP address to the MAC address of the device but that appeared unreliable. Furthermore, my internet provider already has a host name on the world wide web set for me so there is also no need for that step. Although this host name is a bit clumsy as it contains the whole IP-address it can be used. In practice, the user should not need to use this host name but it will be used for a dynamic link to the web site(s).

An important issue is the security of the web site as it provides the access from the world outside to the local area network. Again, there are many descriptions – right and wrong – that describe how to do this. One that, in my humble opinion, is very well written and stands out for clarity is the answer written by Thomas Ward in response to problems associated with this issue. It clearly describes how to set ownership of the various folders as are accessible from outside.

The second step involves setting up the Apache web server so that it will pass on html-information from the various other RPis in the local area network, such as control of the central heating system, solar heaters, etc. to the outside world without compromising  the machines or the network. Of course the web site of Apache has a description, albeit a bit brief. A better description was by LeaseWeb Labs, but actually a combination of various examples finally gave the hint. The essence is to set up the reverse proxy virtual host configuration in “/etc/apache2/sites-available/yourwebsite-proxy.conf”. Mine essentially looks like

<VirtualHost *:80>
ServerName www.yourwebsite.com
DocumentRoot /var/www/html
ProxyPreserveHost On
ProxyRequests off
ProxyPass /pi1 http://RPi1.fritz.box:8083
ProxyPassReverse /pi1 http://RPi1.fritz.box:8083
ProxyPass /pi2/ http://RPi2.fritz.box/~pi/
ProxyPassReverse /pi2/ http://RPi2.fritz.box/~pi/
</VirtualHost>

From the web, the machines are now available as www.yourwebsite.nl/pi1 etc. The ServerName is the one provided by my provider. the other names come from the router and host name settings. There are two examples, one where a port is different, 8083, from the standard 80 and one where the html-information is in another directory. One remark though: it is possible to replace the host names by their IP-addresses; this is extremely helpful while testing.

Finally, there are free services that test the security of the web site. I tried ScanMyServer and it gave 60%; most problems are associated with the older version of Apache but there is no more recent version available for RPi or one has to do the compiling and further processing oneself. For the time being good enough.

 

Melbourne: familiebezoek in Heidelberg, Victoria

Laatste dag in Australie. Morgen gaan we beginnen aan de lange reis terug naar Nederland. Het was een schitterende ochtend dus we besloten tijdens het ontbijt om een wandeling te maken door de koninklijke botanische tuin van Melbourne.

De tuin is redelijk klassiek ingericht en laat binnen- en buitenlandse bomen en planten zien. Het bleef mooi weer dus we zijn door de Victoria tuin en de Koningstuin gelopen naar het centrum. Daar een eenvoudige lunch genomen en toen terug gelopen. De lucht begon wat te betrekken.

In de namiddag zijn we vanuit het motel naar het huis van mijn tante Paula gelopen. We waren iets te vroeg dus we konden meehelpen met het inrichten van de kamer voor het bezoek dat ze verwachtte. Mijn nicht Elizabeth is de dag er op jarig en dat zou ze ook vieren. Langzamerhand kwam de familie binnen en we hebben een gezellige avond gehad met de (klein)kinderen van Paula. Prima met iedereen kunnen praten over hoe onze opvoedingen parallel en toch grotendeels gescheiden verliepen. Veel foto’s daarbij bekeken die weer nieuwe herinneringen opriepen. Het was heel gezellig.