Our demonstrations are always fun and engaging. What Demo is this? #Air #Chemistry #CowsEye #Flight #DesignLab (at New York Hall of Science)

Our demonstrations are always fun and engaging. What Demo is this? #Air #Chemistry #CowsEye #Flight #DesignLab (at New York Hall of Science)

biochemistries:

The 7 crystal systems

Tiny mineral operations transcribe handsomely regular crystals

There are 230 space groups (ways of packing molecules into a regular lattice), but since proteins are chiral — with a “handedness” — that number drops to just 65.
Each of these can be assigned to one of the 7 crystal systems, above. The system is determined by the shape and dimensions of what’s known as the unit cell, the lattice’s fundamental repeating unit.
Below, crystals of insulin ⇢ via ⇢


Crystallisation requires the ordered formation of large (>0.1mm dimensions), stable crystals with sufficient long-range order to diffract X-rays. Structures from X-ray diffraction are only as good as the crystals they are obtained from.
To form a crystal, protein molecules assemble into a periodic lattice from super-saturated solutions (starting with pure protein and adding precipitants to perturb protein-solvent interactions). The equilibrium in solution shifts towards protein-protein association, and at some point nucleation sites form — a critical first step.
This stage is followed by expansion, and cessation as the crystal’s size reaches its limit. Crystals are produced in labs by vapour diffusion — the standard method, good for small volumes and commonly in what’s known as a ‘hanging drop' — and less commonly by equilibrium dialysis — for low and high ionic strength solutions, equilibrating with a solution of precipitant which seeps across a semipermeable membrane inducing formation of a crystal.
There’s currently some very intriguing work being done looking into the processes of nucleation and crystal growth on so-called “labs-on-a-chip”: microfluidic devices which allow highly controlled and precisely observed high-throughput screening of protein crystals.
This is a particularly interesting use of the equilibrium dialysis method that seems to hold some definite advantages over the easy setup of vapour diffusion — particularly as refining the parameters for crystal growth is crucial for getting the best quality structures possible.


The microfluidic toolbox to manipulate liquids in networks of microchannels with 1–100 μm length scales. Such networks mimic classical experiments performed in a laboratory, but with an unequalled control of the transport phenomena. In the specific context of crystallization, these fluidic tools essentially permit the manipulation of aqueous solutions around room temperature. The range of application was originally quite limited but constant progress in the microfluidic technology now yields original features that permits the researcher to:
1. Perform high-throughput data acquisition using crystallization assays down to 1 nL;
2. Design specific kinetic routes using the excellent control of the mass and heat transfers due to the reduction of the length scales and on-chip integration of sensors and actuators;
3. Bring new experimental conditions to investigate crystallization, with no turbulence, no or little gravity effect, confinement, and large surface/volume ratio.
Additionally, the small volumes V of microfluidics are of special interest for nucleation. The mean nucleation time (∝ 1/V) may exceed the growth kinetics of the crystals and only one nucleation event is therefore statistically observed: this mononuclear mechanism is essential to estimate nucleation kinetics and investigate polymorphism.


♦ Leng and Salmon (2009) Microfluidic crystallization. Lab Chip, 9: 24‒34.

biochemistries:

The 7 crystal systems

Tiny mineral operations transcribe handsomely regular crystals

There are 230 space groups (ways of packing molecules into a regular lattice), but since proteins are chiral — with a “handedness” — that number drops to just 65.

Each of these can be assigned to one of the 7 crystal systems, above. The system is determined by the shape and dimensions of what’s known as the unit cell, the lattice’s fundamental repeating unit.

Below, crystals of insulin  via 

image

image

Crystallisation requires the ordered formation of large (>0.1mm dimensions), stable crystals with sufficient long-range order to diffract X-rays. Structures from X-ray diffraction are only as good as the crystals they are obtained from.

To form a crystal, protein molecules assemble into a periodic lattice from super-saturated solutions (starting with pure protein and adding precipitants to perturb protein-solvent interactions). The equilibrium in solution shifts towards protein-protein association, and at some point nucleation sites form — a critical first step.

This stage is followed by expansion, and cessation as the crystal’s size reaches its limit. Crystals are produced in labs by vapour diffusion — the standard method, good for small volumes and commonly in what’s known as a ‘hanging drop' — and less commonly by equilibrium dialysis — for low and high ionic strength solutions, equilibrating with a solution of precipitant which seeps across a semipermeable membrane inducing formation of a crystal.

There’s currently some very intriguing work being done looking into the processes of nucleation and crystal growth on so-called “labs-on-a-chip”: microfluidic devices which allow highly controlled and precisely observed high-throughput screening of protein crystals.

This is a particularly interesting use of the equilibrium dialysis method that seems to hold some definite advantages over the easy setup of vapour diffusion — particularly as refining the parameters for crystal growth is crucial for getting the best quality structures possible.

image

The microfluidic toolbox to manipulate liquids in networks of microchannels with 1–100 μm length scales. Such networks mimic classical experiments performed in a laboratory, but with an unequalled control of the transport phenomena. In the specific context of crystallization, these fluidic tools essentially permit the manipulation of aqueous solutions around room temperature. The range of application was originally quite limited but constant progress in the microfluidic technology now yields original features that permits the researcher to:

1. Perform high-throughput data acquisition using crystallization assays down to 1 nL;

2. Design specific kinetic routes using the excellent control of the mass and heat transfers due to the reduction of the length scales and on-chip integration of sensors and actuators;

3. Bring new experimental conditions to investigate crystallization, with no turbulence, no or little gravity effect, confinement, and large surface/volume ratio.

Additionally, the small volumes V of microfluidics are of special interest for nucleation. The mean nucleation time (∝ 1/V) may exceed the growth kinetics of the crystals and only one nucleation event is therefore statistically observed: this mononuclear mechanism is essential to estimate nucleation kinetics and investigate polymorphism.

image

♦ Leng and Salmon (2009) Microfluidic crystallization. Lab Chip9: 24‒34.

Today’s Google doodle honors Percy Julian, and so does PBS:
pbsthisdayinhistory:

April 11, 1899: Chemist Percy Julian Is Born
On this day in 1899, chemist Percy Julian (today’s Google Doodle) was born. Julian held more than 100 chemical patents, wrote scores of papers on his work, and received dozens of awards and honorary degrees. The grandson of Alabama slaves, Percy Julian met with every possible barrier in a deeply segregated America. He was a man of genius, devotion, and determination. As a black man he was also an outsider, fighting to make a place for himself in a profession and country divided by bigotry—a man who would eventually find freedom in the laboratory. Watch NOVA's “Forgotten Genius,” the story of how African American Percy Julian defied the odds to become a famous chemist.
Photo: NOVA

Today’s Google doodle honors Percy Julian, and so does PBS:

pbsthisdayinhistory:

April 11, 1899: Chemist Percy Julian Is Born

On this day in 1899, chemist Percy Julian (today’s Google Doodle) was born. Julian held more than 100 chemical patents, wrote scores of papers on his work, and received dozens of awards and honorary degrees.

The grandson of Alabama slaves, Percy Julian met with every possible barrier in a deeply segregated America. He was a man of genius, devotion, and determination. As a black man he was also an outsider, fighting to make a place for himself in a profession and country divided by bigotry—a man who would eventually find freedom in the laboratory.

Watch NOVA's “Forgotten Genius,” the story of how African American Percy Julian defied the odds to become a famous chemist.

Photo: NOVA

(Source: video.pbs.org)

explainers-nysci:

That’s cold [x]

explainers-nysci:

That’s cold [x]

Don’t forget to give thanks for eugenol and isoeugenol today. http://bit.ly/IsFYtL

Don’t forget to give thanks for eugenol and isoeugenol today. http://bit.ly/IsFYtL

Sparking Curiosity

image

Glass vials, a row of chemicals, and an alcohol lamp. Perhaps nothing symbolized the excitement of science in the early to mid-20th century better than a chemistry set. The classic kits got kids tinkering, experimenting and thinking about science. In the process, they inspired a generation of inventors and scientists, some of whom became Nobel Prize-winners. But somewhere along the way, spurred by safety concerns and legal changes, chemistry sets faded in popularity.

A new competition, launched this week, aims to find the 21st century version of the classic chemistry set. A collaboration between the Gordon and Betty Moore Foundation and the Society for Science & the Public, the Science, Play and Research Kit competition (SPARK) challenges participants to generate a new set of experiences and activities that encourage imagination and interest in science, bringing the spirit of the classic chemistry set to today’s children.

Margaret Honey, NYSCI’s president and CEO, is an advisor to the competition, which will offer tangible ways to get more kids experimenting with science.

The competition’s top award is for the best science kit prototype with a prize of $50,000. Additional prizes ranging from $1,000 – $25,000 will be awarded for runners-up and idea submissions.

explainers-nysci:

In accompaniment to the interview video, the vivacious explainer Saijah Williams tells us a few things about the relatively new field of molecular gastronomy or “modern cooking”, her love for baking and where she sees herself with NYSCI in the future. 

MW: So can you explain molecular gastronomy to those of us who have never heard of it?

SW: Molecular gastronomy studies the physical aspects as well as the chemical aspects of ingredients during cooking. It also studies how the ingredients interact and affect each other under different temperatures.

MW: How did this interest start?

SW: I love food and I love science; [molecular gastronomy] is a combination of the two, so it’s perfect. It turns cooking into a form of scientific experimentation.

You know how we use liquid nitrogen in the Chem demo? Some molecular gastronomical meals use liquid nitrogen to prepare.

MW: That sounds like a science experiment! Do you need any special a degree or PhD. to prepare a molecular gastronomy meal [laughs]?

SW: Yeah there are courses at certain colleges for molecular gastronomy and also special culinary schools.There are recipes that one can follow also. They even sell kits [in bookstores] to get you started.

There is a show on Netflix, called “Quantum Kitchen” it’s all about molecular gastronomy. The chef [Marcel Vigneron] in it goes all out for his meals. He puts a lot of time and thoughts and uses all sorts of techniques to prepare his meals.

MW: A meal like that can’t come cheap. Speaking of expensive meals, I heard there are restaurants [such as Corton located in Tribeca] that use special molecular gastronomical techniques to prepare their meals. The waiting lists for the restaurants are unbelievably long.

SW: I would love to dine at one but they are so expensive and the waiting lists are for months.

MW: Do you cook a lot?

SW: I am more of a baker than a cook. I usually bake extravagant cakes for the holidays. Last year for Halloween, I baked a graveyard themed cake with cookies for tombstones and worms, the gummy type of course.

MW: So we can anticipate an extravagant cake this Halloween [laughs]?

SW:  Possibly. I haven’t baked in a while and Halloween, which is my favorite holiday, gives me the perfect opportunity to make a really great cake. I’m thinking of ideas right now, so we will see!

MW: You’ve been with the Hall for 2 years, now. So where do you see yourself in the future with the Hall? 

SW: I want to move up the Science Career Ladder, try to go as far as I can, and reach the highest rung.

-       Interviewed by Margaret Wang

-       Interview edited for clarification purposes