Wine tears

Perhaps drinking wine makes you all emotional. Perhaps drinking wine reminds you how you secretly enjoy beer better but then why do you have this weird stemmed glass in your hand? Perhaps you remember your early twenties when you lived in France and okay-to-good wine was very cheap and now you live in a country where okay-to-good wine is no longer cheap and cheap wine is sure to give you a head ache the next day. Perhaps drinking whine makes tears run out of your eyes.

Did you ever stop to consider that crying over wine makes the wine cry as well?

Just kidding. I actually wanted to talk about wine tears. Which is the weird phenomenon where a ring of clear liquid forms in a wine of glass that has a bunch of droplets forming from it. Tears of wine. It’s thing. A chemistry thing.

Image result for wine tears
No need to cry, it’ll be alright!

This type of “tears” appear because alcohol, you know that thing that is about 13% of that glass of wine your crying into, has a lower surface tension than water, which is that thing that most of the rest of that wine is made of. So like 85%, plus or minus a percent depending on how much crying you’ve done into the glass.

At the surface of the wine in your glass, where the liquid surface meets the side of the glass, capillary action causes the liquid to rise up the side of the glass. This thin film of liquid contains water and alcohol, both evaporate. Due to the higher vapor pressure of alcohol, it evaporates quicker than the water. This decreases the alcohol concentration in that liquid film, and consequentially also the surface tension, causing more liquid to rise up. Eventually, the liquid forms droplets that fall back into the wine. Gravity, it always get’s ya!

A diagram explaining how tears of wine form.
Also called the Marangoni effect, γ is surface tension.

So there. When you drink wine, just remember, you’re not the only one crying.

Forget diamonds, liquid crystals are a girl’s best friend!

A few months ago I lost my mood ring. Which is very discerning; I haven’t been able to tell what my mood is since then!

I was reminded of my lack of mood-reading device in Vancouver last weekend. I was in one of those fantasy-merch shops that sells lots of dragon statues. I was admiring their collection of mood rings and wondering whether I should buy a new, when I suddenly realized I didn’t actually know how mood rings work.

My friend and I used to have full conversations consisting of pictures of our mood rings. “It’s really cold out” was a picture of a black or brown ring.

To the google!

Thermochromic materials

Mood rings don’t actually tell what your mood is (sorry). They do give some indication of your skin temperature, which I guess is slightly related to your mood but probably more related to the weather and how cold you’refeeling. Created in 1975 by New Yorkers Josh Reynolds and Maris Ambats, mood rings were a fad in the 1970s, and probably again in the 1990s if I remember correctly. To be honest, they’ve never really left the mystic thingumabob shops, or souvenir shops (as you might be able to tell by the Celtic knot design in the picture above; I bought the rings for my friend and me in a Scottish souvenir shop).

The change-changing part of a mood ring is a thermochromic material, i.e. a material that changes color (chroma -χρῶμα) due to a change in temperature (thermosθερμός).*

There are different examples of thermochromic materials and a number of different applications. Those t-shirts that change in color if you press your hand on them. Those cups that change color when containing a hot liquid. Those little thermometer rulers that change color if you hold them in your hand. And mood rings.

Liquid crystals

The type of material in a mood ring, that changes color according to changing temperature, is a liquid crystal.

If you had some intro to chemistry at some point, you might remember hearing that crystals have a very organized structure, with atoms (or molecules) forming a lattice. Perhaps you did an experiment where you made salt crystals by evaporating water from salt water in a dish. But you probably remember that crystals were not liquid.

Then what are liquid crystals? Basically, it’s a state of matter which lies in between liquids and crystals. Usually, liquid crystal molecules are elongated, so depending on their packing they have more crystal-like properties (dense packing) or more liquid properties (looser packing). Depending on their “phase”, i.e. structural organisation and packing, the optical properties of liquid crystals change.

Liquid crystals consist of elongated moleduces that change their optical properties depending on their organization. Image from: https://summerofhpc.prace-ri.eu/lost-in-a-liquid-crystal/

The molecules in a liquid crystal can take up different degrees of order:

  1. No order; basically the material is a liquid with properties of a fluid. (A in the very professional sketch below.)
  2. Some order; the molecules sort of align in the same direction, but not along a plane (B).
  3. More order; the molecules start organizing themselves along planes (C).
  4. Full order; all molecules are neatly arranged in a regular lattice structure. Wait, this is a full crystal! (D)
I’m getting into the habit of creating illustrations on origami paper.**

As stated, with changing orientation and order, the optical properties change, similar to the collagen from a previous post. Depending on how organized the molecules are, different light wavelengths are reflected by the mood rind “gem”. In other words: the warmer the mood ring gem gets, the less organized the liquid crystal molecules are, and that causes a shift in color.

So if you’re feeling unsure about your mood, mood rings don’t actually help, but I’ve found that they are quite a conversation starter. But now, instead of handing your ring to whomever exclaims “Oh cool! A mood ring! Can I try it on?“, you can also explain exactly how it (doesn’t) work.

I just bought myself a new one. ***


Cover image credit: Kaszynski lab

* Using any excuse to use the Greek alphabet for something other than fraternity names. I now walk to work through Fraternity Lane (not the actual name), so I’m constantly reminded of the letter φ.

** Bonus pic – origami flowers from those same pieces of paper:

*** Bonus pic 2 – New ring!

150 years of elements

Here’s a riddle for you: what hangs in every chemistry class in middle and high school, leads to the creation of several nerdy t-shirts, and celebrated is 150th birthday yesterday?

Okay, it’s not a very funny riddle. Nor is it a very difficult one. The answer is: the periodic table of elements, first published on the 6th of March 1869 – exactly 150 years minus-one-day ago – by the Russian chemist Dmitri Mendeleev.

Professor scheikunde Dmitri Mendelejev in zijn bureau aan de universiteit van Sint-Petersburg.

Professor Dmitri Mendeleev

From Alchemy to Chemistry

In the olden days, we would have turned to alchemists to ask our questions about fundamental elements and what stuff makes up stuff. Even though alchemy was not really a “science” in the pure sense of the word – it relied heavily on spiritualism, philosophy and even magic – it set the stage for what would later become chemistry. And while alchemists were mostly trying to turn random metallic rocks into gold, or brew an elixir for eternal life, they were the first that attempted to identify and organize the different substances occurring in nature. The Elements.

The earliest basic elements were considered to be earth, water, air and fire. The discovery of what we might call “chemical elements” really kicked off in 1669 in Germany, by a merchant by the name of Henning Brand. Like many chemists-avant-la-lettre (alchemists), he was trying to discovery the Philosopher’s stone. However, like many muggles, he was not acquainted with Nicolas Flamel and did not succeed (Side note: Nicolas Flamel was actually based on a real person!). In stead, while distilling urine – as you would while trying to create eternal life – he discovered a glow-in-the-dark substance: phosphorous. And with that, the element finding had begun.

Chemistry can be considered to have originated in 1789, when Antoine-Laurent de Lavoiser wrote what is said to be the first modern chemistry textbook. In this book, he defined an element as a substance that can not be broken down to a simpler substance. A fundamental particle. This definition lasted until the discovery of subatomic particles (electrons, protons and neutrons) in the 1930s. Lavoisier’s list of elements included things like oxygen, hydrogen and mercury, but also light.

Dalton’s symbols of the elements. 1806 (Wellcome Images). Combine numbers 24 and 28 with some gin and get a nice cocktail.

Let’s glaze over most of the 19th century, where multiple different scientists realized that the atomic weights of elements were multiples of that of hydrogen (William Prout) and how there was a certain periodicity in terms of physical and chemical properties when the elements were arranged according to their atomic weights (Alexandre-Emile Béguyer de Chancourtois). The early attempts to classify the elements were based on this periodicity, and eventually, our Mendeleev came along.

“Chemical Solitaire”

The Russian chemist Dmitri Mendeleev is the father of the modern periodic table. In fact, in Belgium, we call the periodic table of elements “Mendeleev’s table of elements”. After (allegedly) playing “chemical solitaire” on long train journeys – quite common in Russia, I’m sure – he came up with a classification method based on arranging the elements by atomic mass and classifying them according to their properties. Elements in one group (column) have the same number of valance electrons: the number of electrons in the outer shell of the atom and available to react with other elements. Elements in the same column therefore from bonds with other elements in the same way, and form similar types of materials.

Because there were some gaps in the table – some atomic weights missing – he predicted the existence of elements that were yet to be discovered, and what their chemical properties would be. And this is what made his classification method so ground-breaking.

And indeed, in 1885 germanium was discovered, with properties – as predicted – similar to silicon. Same for gallium in 1875 (similar properties as aluminium) and scandium in 1879 (similar properties as boron), filling up some gaps in his periodic table.

The periodic table from Osnovy khimīi by Dmitry Ivanovich Mendeleyev, 1834-1907. S.-Peterburg : Tip. t-va “Obshchestvenna︠i︡a polʹza, 1869-1871.

The gaps are filled

Since 1869, the gaps in the periodic table have been filled, and new elements are discovered or created every few years adding to the high end of the table. The last update to the periodic table was in 2016, when the elements nihonium (113), moscovium (115), tennessene (117) and oganesson (118) were added to the list.

So today – okay, yesterday – we celebrated 150 years of chemical element classification, the anniversary of the periodic table of elements, and the collective pain of decades of highschoolers memorizing atomic masses and number of valance electrons.

The table of elements as usually taught today, with pictures of applications for each element (from https://elements.wlonk.com/index.htm).

Inspired by the coverage by vrt nws.

The interactive table of elements in the cover picture is from
http://periodictable.com/

A Nobel Cause

So, the news is out. At least in terms of the sciency Nobel Prizes (sorry Economic Sciences, you don’t really count here), the 2018 Laureates have all been announced, so here’s a short overview of what was Nobel-Prize-Worthy this year:

1. Nobel Prize in Chemistry (press release)

And… *drumroll* the Nobel prize in Chemistry goes to Prof. Frances H. Arnold, Prof. George Smith and Sir Gregory Winter for their contributions to protein biology, where they all worked on directed evolution of proteins.

Directing protein evolution is used to create proteins with a specific function that can be used in biofuel, pharmaceutical, and medicine manufacturing. Half of the Nobel Prize was awarded to Prof. Arnold, who works on directed evolution of enzymes (proteins that are used to accelerate or direct chemical reactions). The other half, that of Prof. Smith and Sir Winter, celebrated a method called phage display. This process uses viruses to develop specific proteins that can be used for medical purposes.

My personal excitement for this prize:
Well, Prof. Arnold is a professor in bioengineering, which is, in my opinion, an underacknowledged field, so that’s pretty cool. And this has nothing to do with the fact that I’ve studied bioengineering. Nothing at all.

 

2. The Nobel Prize in Physiology or Medicine (press release)

The Nobel prize in Physiology or Medicine was awarded to Jim Allison and Tasuku Honjo for their work in cancer therapy. By now, the concept of “immune therapy” may not sound extremely new anymore. However, just think about how amazing it is: someone’s immune system (in other words, an attack system that is already present in your body) can be used to fight cancer cells (which isn’t really straightforward – cancer cells originate from normal cells so are not detected as “foreign” by the immune system).
My personal interest in this prize: 
First of all, yay for biology completely highjacking the Nobel Prizes. But on the topic: radiotherapy and chemotherapy are both notorious to have a huge amount of side effect. By effectively using the natural defense system of the body, immune therapy usually is a lot less taxing on a patient, which I think is a laudable goal.

3. The Nobel Prize in Physics (press release)

*Final Drum Roll, please*

The Nobel Prize in Physics is all about lasers (Did you know that LASER is an acronym for “Light Amplification by Stimulated Emission of Radiation? Well, you do know). Arthur Ashkin was honors for his development of optical tweezers (which I will simply explain by referring you to my fabulous friend who has worked with optical tweezers herself) and the other half was awarded to Donna Strickland and Gerard Mourou for their work on laser pulses. The most known application of laser pulses is in laser eye surgery.

My personal input to this prize:
I have two thoughts, first, how has this not won a Nobel Prize yet? Actually, to be honest, I think that quite often when the Nobel Prizes, which is probably why they get a Nobel Prize in the first place. The other thought has to do with the same reason why this prize has been in the press a lot: it has been 55 years since a woman won a physics Nobel prize. Only two other women have a Nobel Prize in Physics to their name: Marie Skłodowska-Curie (obviously!) and Maria Goeppert-Mayer (go google her, now).

Some thoughts on women and Nobel Prizes

Historically, science has always been pretty male-dominated. And even now, women are underrepresented in research: worldwide the female share of persons employed in R&D is approximately 30% and I will not even get into high-level academics here.

In terms of Nobel Prizes, as of this year, there have been 49 women who have won Nobel Prizes (that’s all of them), compared to 844 men. In the sciency fields, five women have won the Nobel Prize in Chemistry (2.8%), twelve have won the Nobel Prize in Physiology or Medicine (5.6%), and – as stated – three have won the Nobel Prize in Physics (1.4%). Actually, only one woman has won the Nobel Memorial Prize in Economic Sciences (also 1.4%), but that doesn’t really count as a science anyway!

In any case, none of the Nobel Prizes have a good track record, and it makes me a bit sad that “First woman Physics Nobel winner in 55 years” is a news headline, but ah well, we may have come some part of the way but we are not there yet.

And until we are, having positive role models of all shapes and sizes and sexes for STEM fields is crucial. As a wannabe science-communicator, or science-populizer if you will, one of my aims is exactly that. So that every child can look up to a scientist and think “that could be me!”

And – even if I say so myself – I think that’s a pretty noble cause.

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