Alle berichten van gkoper

Minibieb Diamantbuurt

Het idee om een boekhuisje te bouwen was er al veel langer. Het begon met de vaststelling lang geleden dat we wel een hoop boeken hebben maar dat lang niet alle het bewaren waard zijn. Weggooien is een mogelijkheid, maar het is aardiger om iemand een plezier er mee te doen.

Ergens in 2002 begon ik een paar boeken “in het wild” achter te laten. Achterin doe je dan een notitie waarop een code staat die verwijst naar bookcrossing, dat is een webstek waar je dan informatie hebt achtergelaten over het boek. Het aardige is dat je dan kunt volgen wat er met het boek gebeurt. Maar dan moeten de vinders dat wel doen en daar ontbrak het nog al eens aan. Er zijn op die manier nog zo’n 7 boeken in het wild. Geen idee wat er van gekomen is.

Daarna sluimerde voor langere tijd het idee om zelf een boekhuisje te maken. Toen ik een tijd in de lappenmand was begon het project meer vorm te krijgen. Er kwam een soort van bouwtekening bij een zoektocht op het wereldwijde web tevoorschijn waaruit de gangbare dimensies gehaald konden worden. Dat was al een aardig begin.

Daarna begon het verzamelen van de materialen. Mijn eigen houtvoorraad bracht al een kant. Een kennis had ook nog wat plaatwerk en toen had ik ook een achterkant en een bodem. Na een klus bleven ook de zijkanten en het dak over. De planken aan de binnenkant kwamen uit nog liggende restjes. Het voordeurraam kon ik van een oud stuk kunstofplaat maken. Daarmee was in ieder geval goed te beginnen en stukje bij beetje werd het geheel opgetrokken. Ik koos voor een versie met een los dak. Met beugeltjes wordt het op zijn plaats gehouden, maar als het nodig is kan het afgenomen worden. Vanuit de voordeur is onderhoud nu eenmaal lastig te doen.

In de zomer en zeker door de Australiëreis is het projekt tot een stop gekomen. Af en toe nog wat bijwerken, beitsen en zo, maar daar bleef het bij. Er moest een dakafwerking komen. Op een gegeven moment bleek het dakje bij de voordeur te lekken en dat was een mooie gelegenheid om wat van het afdichtmateriaal te gebruiken voor het boekenhuisje. Nog wat hang en sluitwerk maar toen was het dan eindelijk afgerond.

Gisteren is het projekt dan toch afgerond. De dag er voor was er al een steun gemaakt voor het kastje en dat ging toen in de grond. Boeken er in en en klaas is Kees. Nu nog aanmelden bij de diverse instanties, zoals minibieb en geocaching, en dan is het helemaal af.

Lekkage verholpen (?)

Welaan, het dak is netjes afgeplakt. De overstort aan de voorkant is netjes afgedekt met een waterdichte en UV-bestendige EPDM-folie. Het houtwerk is hersteld en netjes opgeschilderd. Kortom, het ziet er puik uit.

Een paar weken afgewacht. Gelukkig ging het goed stormen en regenen zodat de meer extreme weertypen voorbijkwamen. En de bovenrand van de deur bleef droog. Eerst een isolatielaag over de bestaande en beschadigde verflaag en toen weer latex er over. Toch nog wat verkleuring. Wellicht wat te zuinig geweest met de isolatielaag aanbrengen. De tweede keer ging het wel goed en de boel is nu weer netjes wit. Tot nu toe blijft dat zo. We kijken het aan ….

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.