Landmarks of modern Chemistry: The mass spectrometer

Mass spectrometer can be considered as a huge landmark in modern chemistry. It was designed by scientist F.W. Aston in 1919 to analyse positive rays. This was later modified by Aston and A.J Dempster to increase its sensitivity.

What is a mass spectrometer?
The mass spectrometer is an instrument which can be used to measure,
         -masses of atoms and molecules
         -relative concentrations of atoms and molecules
 It makes use of the basic magnetic field acting on a moving charged particle. Thereby we get a  magnetic force acting on the particle..If something is moving and you subject it to a sideways force, instead of moving in a straight line, it will move in a curve - deflected out of its original path.





How is it done?

Suppose you had a cannonball travelling past you and you wanted to deflect it as it went by you. All you've got is a jet of water from a hose-pipe that you can squirt at it. Frankly, its not going to make a lot of difference! Because the cannonball is so heavy, it will hardly be deflected at all from its original course.
But suppose instead, you tried to deflect a table tennis ball travelling at the same speed as the cannonball using the same jet of water. Because this ball is so light, you will get a huge deflection.
The amount of deflection you will get for a given sideways force depends on the mass of the ball. If you knew the speed of the ball and the size of the force, you could calculate the mass of the ball if you knew what sort of curved path it was deflected through. The less the deflection, the heavier the ball.
It is the same principle applied in this case too.

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Atoms and molecules cannot be deflected by magnetic fields. Electrically charged particles are affected by a magnetic field which means that its the ions that are deflected.

Mass spectrometer protocols

1) Ionization 
The atom or molecule is ionized by removing one or more electrons off to give a positive ion. This is true even for things which you would normally expect to form negative ions (chlorine, for example) or never form ions at all (argon, for example). Most mass spectrometers work with positive ions.Therefore, in order to ionize a particular atom or molecule we must supply the necessary ionization enthalphy. This is done in the ionization chamber in the mass spectrometer.


.2)Acceleration
The ions are accelerated so that they all have the same kinetic energy.


3)Deflection
The ions are then deflected by a magnetic field according to their masses. The lighter they are, the more they are deflected.
The amount of deflection also depends on the number of positive charges on the ion - in other words, on how many electrons were knocked off in the first stage. The more the ion is charged, the more it gets deflected.
In other words deflection depends on the charge/mass (e/m) ratio. If e/m is high then the deflection is high.

4)Detection
The beam of ions passing through the machine is detected electrically



Special points

Neccesity of a vacuum chamber.

It's important that the ions produced in the ionization chamber have a free run through the machine without hitting air molecules.


Ionization chamber
The vaporised sample passes into the ionisation chamber. The electrically heated metal coil gives off electrons which are attracted to the electron trap which is a positively charged plate.
The particles in the sample (atoms or molecules) are therefore bombarded with a stream of electrons, and some of the collisions are energetic enough to knock one or more electrons out of the sample particles to make positive ions.
Most of the positive ions formed will carry a charge of +1 because it is much more difficult to remove further electrons from an already positive ion. The second ionization energy is comparatively higher.
These positive ions are forced out into the rest of the machine by the ion repeller which is another metal plate carrying a slight positive charge.
As you will see in a moment, the whole ionisation chamber is held at a positive voltage of about 10,000 volts. Where we are talking about the two plates having positive charges, these charges are in addition to that 10,000 volts.


Acceleration mechanism
The positive ions are repelled away from the very positive ionisation chamber and pass through three slits, the final one of which is at 0 volts. The middle slit carries some intermediate voltage. All the ions are accelerated into a finely focused beam.

Deflection mechanism

Different ions are deflected by the magnetic field by different amounts. The amount of deflection depends on:
         -the mass of the ion (lighter ions are deflected more than heavier ones)
         -the charge on the ion (ions with 2 (or more) positive charges are deflected more than ones with                                                 only 1 positive charge)
These two factors are combined into the charge/mass ratio. It is given the symbol e/m.
In the above diagram, ion stream A is most deflected - it will contain ions with the largest e/m ratio. Ion stream C is the least deflected - it contains ions with the lowest e/m ratio.
Assuming 1+ ions, stream A has the lightest ions, stream B the next lightest and stream C the heaviest. Lighter ions are going to get more deflected than heavy ones.

Detection
Only ion stream B makes it right through the machine to the ion detector. The other ions collide with the walls where they will pick up electrons and be neutralised. Eventually, they get removed from the mass spectrometer by the vacuum pump.
When an ion hits the metal box, its charge is neutralised by an electron jumping from the metal on to the ion (right hand diagram). That leaves a space among the electrons in the metal, and the electrons in the wire shuffle along to fill it.
A flow of electrons in the wire is detected as an electric current which can be amplified and recorded. When more ions are detected more would be the current too.

Detection of other ions
How might the other ions be detected - those in streams A and C which have been lost in the machine?
Remember that stream A was most deflected - it has the greatest value of e/m (the lightest ions if the charge is 1+). To bring them on to the detector, you would need to deflect them less - by using a smaller magnetic field (a smaller sideways force).
To bring those with a smaller e/m value (the heavier ions if the charge is +1) on to the detector you would have to deflect them more by using a larger magnetic field.
If you vary the magnetic field, you can bring each ion stream in turn on to the detector to produce a current which is proportional to the number of ions arriving. The mass of each ion being detected is related to the size of the magnetic field used to bring it on to the detector. The machine can be calibrated to record current (which is a measure of the number of ions) against m/e directly. (Here the reciprocal of e/m is considered)The mass is measured on the 12C scale.

Mass spectrometer output
The output from the chart recorder is usually simplified into a "stick diagram". This shows the relative current produced by ions of varying mass/charge ratio.

Above recorded is a chart of Molibdium.
You may find diagrams in which the vertical axis is labelled as either "relative abundance" or "relative intensity". Whichever is used, it means the same thing. The vertical scale is related to the current received by the chart recorder - and so to the number of ions arriving at the detector: the greater the current, the more abundant the ion.
As you will see from the diagram, the commonest ion has a mass/charge ratio of 98. Other ions have mass/charge ratios of 92, 94, 95, 96, 97 and 100.
That means that molybdenum consists of 7 different isotopes. Assuming that the ions all have a charge of 1+, that means that the masses of the 7 isotopes on the carbon-12 scale are 92, 94, 95, 96, 97, 98 and 100.


Therefore, from all the above facts we can conclude that mass spectrometer is a great invention which helped chemists to find out about isotopes.


                                           

Graphene

Carbon is an element with a large number of allotropes mainly divided into two categories.
         - crystalline structures
         - amorphous forms
Carbon has different allotropes such as Diamond, Graphite, Fullerene, Carbon nano tubes etc.
Graphene is the basis of such allotropes.

Graphene is made of a single layer of carbon atoms that are bonded together in a repeating pattern of hexagons. Graphene is one million times thinner than paper; so thin that it is actually considered two dimensional.




Carbon is an incredibly versatile element. Depending on how atoms are arranged, it can produce hard diamonds or soft graphite. Graphene’s flat honeycomb pattern grants it many unusual characteristics, including the status of strongest material in the world. Columbia University mechanical engineering professor James Hone once said it is “so strong it would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap,” according to the university.
These single layers of carbon atoms provide the foundation for other important materials. Graphite — or pencil lead– is formed when you stack graphene. Carbon nanotubes, which are another emerging material, are made of rolled graphene. These are used in bikes, tennis rackets and even living tissue engineering.

Amazingly Weird properties of Graphine

Conductive: Electrons are the particles that make up electricity. So when graphene allows electrons to move quickly, it is allowing electricity to move quickly. It is known to move electrons 200 times faster than silicon because they travel with such little interruption. It is also an excellent heat conductor. Graphene is conductive independent of temperature and works normally at room temperature.

Strength: As mentioned earlier, it would take an elephant with excellent balance to break through a sheet of graphene. It is very strong due to its unbroken pattern and the strong bonds between the carbon atoms. Even when patches of graphene are stitched together, it remains the strongest material out there.



Flexible: Those strong bonds between graphene’s carbon atoms are also very flexible. They can be twisted, pulled and curved to a certain extent without breaking, which means graphene is bendable and stretchable.

Transparent: Graphene absorbs 2.3 percent of the visible light that hits it, which means you can see through it without having to deal with any glare.

Practical uses of Graphine

The use of graphene in everyday life is not far off, due in part to existing research into carbon nanotubes — the rolled, cylindrical version of graphene. The tubes were popularized by a 1991 paper (subscription required) and touted for their incredible physical qualities, most of which are very similar to graphene. But it is easier to produce large sheets of graphene and it can be made in a similar way to silicon. Many of the current and planned applications for carbon nanotubes are now being adapted to graphene.

Some of the biggest emerging applications are:

Solar cells: Solar cells rely on semiconductors to absorb sunlight. Semiconductors are made of an element like silicon and have two layers of electrons. At one layer, the electrons are calm and stay by the semiconductor’s side. At the other layer, the electrons can move about freely, forming a flow of electricity. Solar cells work by transferring the energy from light particles to the calm electrons, which become excited and jump to the free-flowing layer, creating more electricity. Graphene’s layers of electrons actually overlap, meaning less light energy is needed to get the electrons to jump between layers. In the future, that property could give rise to very efficient solar cells. Using graphene  would also allow cells that are hundreds of thousands of times thinner and lighter than those that rely on silicon.




Intel’s transistors at 32 nano meters. More transistors helped pave the way for cheaper computing.
Transistors: Computer chips rely on billions of transistors to control the flow of electricity in their circuits. Research has mostly focused on making chips more powerful by packing in more transistors, and graphene could certainly give rise to the thinnest transistors yet. But transistors can also be made more powerful by speeding the flow of electrons — the particles that make up electricity. As science approaches the limit for how small transistors can be, graphene could push the limit back by both moving electrons faster and reducing their size to a few atoms or less.



Transparent screens: Devices such as plasma TVs and phones are commonly coated with a material called indium tin oxide. Manufacturers are actively seeking alternatives that could cut costs and provide better conductivity, flexibility and transparency. Graphene is an emerging option. It is non-reflective and appears very transparent. Its conductivity also qualifies it as a coating to create touchscreen devices. Because graphene is both strong and thin, it can bend without breaking, making it a good match for the bendable electronics that will soon hit the market.
Graphene could also have applications for camera sensors, DNA sequencing,gas sensing, material strengthening,water desalination and beyond.

Therefore, in the modern world graphene has been a really important discovery either in hardcore or softcore deeds.

Mapping Genetic repair wins the 2015 Nobel Prize

It is not that easy to get a nobel price. Nobel prize in chemistry thats a huge achievement. It shows how much the world needed to map genetic repairs.

The Nobel Prize in Chemistry 2015 is awarded toTomas Lindahl, Paul Modrich and Aziz Sancar for having mapped, at a molecular level, how cells repair damaged DNA and safeguard the genetic information. Their work has provided fundamental knowledge of how a living cell functions and is, for instance, used for the development of new cancer treatments.

Each day our DNA is damaged by UV radiation, free radicals and other carcinogenic substances, but even without such external attacks, a DNA molecule is inherently unstable. Thousands of spontaneous changes to a cell's genome occur on a daily basis. Furthermore, defects can also arise when DNA is copied during cell division, a process that occurs several million times every day in the human body.

The reason our genetic material does not disintegrate into complete chemical chaos is that a host of molecular systems continuously monitor and repair DNA. The Nobel Prize in Chemistry 2015 awards three pioneering scientists who have mapped how several of these repair systems function at a detailed molecular level.

In the early 1970s, scientists believed that DNA was an extremely stable molecule, but Tomas Lindahl demonstrated that DNA decays at a rate that ought to have made the development of life on Earth impossible. This insight led him to discover a molecular machinery, base excision repair, which constantly counteracts the collapse of our DNA.

Aziz Sancar has mapped nucleotide excision repair, the mechanism that cells use to repair UV damage to DNA. People born with defects in this repair system will develop skin cancer if they are exposed to sunlight. The cell also utilises nucleotide excision repair to correct defects caused by mutagenic substances, among other things.

Paul Modrich has demonstrated how the cell corrects errors that occur when DNA is replicated during cell division. This mechanism, mismatch repair, reduces the error frequency during DNA replication by about a thousandfold. Congenital defects in mismatch repair are known, for example, to cause a hereditary variant of colon cancer.

The Nobel Laureates in Chemistry 2015 have provided fundamental insights into how cells function, knowledge that can be used, for instance, in the development of new cancer treatments.

Prize amount: 8 million Swedish krona, to be shared equally between the laureates.

Its our duty and obligation as Science students to try and develop all these new inventions and discoveries to a whole new level.

Natural Nanomaterials : Halloysite

Yuri Lvov and Rawil Fakhrullin of Bionanotechnology Lab, Kazan Federal University, in cooperation with Wencai Wang and Liqun Zhang of State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology have recently presented in Advanced Materials a broad scope of application of halloysite clay tubes .


It is a natural bio compatible nano material available in thousands of tons at low price, which makes it a good candidate for nano architectural composites. In chemical composition they are similar to kaolin and can be considered as rolled kaolin sheets with inner diameter of 10-20 nm, outer diameter of 40-70 nm and a length of 500-1500 nm. The internal side of halloysite is composed of Al2O3 while the external is mainly SiO2. The inner lumen of halloysite may be adjusted by etching to 20-30% of the tube volume and used as natural nanocontainer for loading and sustained release of chemical agents. These ceramic nanotubes form a "skeleton" in the bulk polymers, enhancing the composite strength and adhesivity. These "skeleton bones" may be loaded with active compounds, like real bones are loaded with marrow, providing additional functionality for polymers (antimicrobial, anti-aging, anticorrosion, and flame-retardancy).

Halloysite tubes can encase enzymes for longer storage, higher temperature, and extended functionality, while the tube's opening allows for delivery of small substrate molecules into the tube interior for biocatalysis. Loading DNA into halloysite is another prospective research direction. As functional nanoblocks, halloysite tubes may be used for building on biological cells, like the formation of spore-like microbial shells providing microorganisms with additional functions. In vitro and in vivo studies on biological cells and worms indicate the safety of halloysite, and furthermore, it can store and release molecules in a controllable manner, making these tiny containers attractive for applications in drug delivery, antimicrobial materials, self-healing polymeric composites, and regenerative medicine.


The material, however, is not biodegradable, as there are no biological mechanisms to degrade this alumo silicate clay in the body, and it cannot be injected in the blood intravenously, but rather may be used for external medical treatment with slow release of encapsulated drugs (e.g., in creams, implants, or wound treatment of tissues).

Lifetime of atoms extended using a mirror

The lifetime of an atom can be extended up to ten times by placing it in front of a short circuit that acts as a mirror. The artificial atom consists of a superconducting circuit on a silicon chip. The interaction between the atom and its mirror image modifies the vacuum fluctuations seen by the atom and thus its lifetime. The microwaves that mediate the interaction between the atom and the mirror flow in a transmission line on the chip.

Credit: Illustration by Moa Carlsson and Lisa Kinnerud, Krantz NanoArt

Researchers at Chalmers University of Technology have succeeded in an experiment where they get an artificial atom to survive ten times longer than normal by positioning the atom in front of a mirror. The findings were recently published in the journal Nature Physics.

If one adds energy to an atom -- one says that the atom is excited -- it normally takes some time before the atom loses energy and returns to its original state. This time is called the lifetime of the atom. Researchers at Chalmers University of Technology have placed an artificial atom at a specific distance in front of a short circuit that acts as a mirror. By changing the distance to the mirror, they can get the atom to live longer, up to ten times as long as if the mirror had not been there.

The artificial atom is actually a superconducting electrical circuit that the researchers make behave as an atom. Just like a natural atom, you can charge it with energy; excite the atom; which it then emits in the form of light particles. In this case, the light has a much lower frequency than ordinary light and in reality is microwaves.

"We have demonstrated how we can control the lifetime of an atom in a very simple way," says Per Delsing, Professor of Physics and leader of the research team. "We can vary the lifetime of the atom by changing the distance between the atom and the mirror. If we place the atom at a certain distance from the mirror the atom's lifetime is extended by such a length that we are not even able to observe the atom. Consequently, we can hide the atom in front of a mirror," he continues.

The experiment is a collaboration between experimental and theoretical physicists at Chalmers, the latter have developed the theory for how the atom's lifetime varies depending on the distance to the mirror.

"The reason why the atom "dies," that is it returns to its original ground state, is that it sees the very small variations in the electromagnetic field which must exist due to quantum theory, known as vacuum fluctuations," says Göran Johansson, Professor of Theoretical and Applied Quantum Physics and leader of the theory group.

When the atom is placed in front of the mirror it interacts with its mirror image, which changes the amount of vacuum fluctuations to which the atom is exposed. The system that the Chalmers researchers succeeded in building is particularly well suited for measuring the vacuum fluctuations, which otherwise is a very difficult thing to measure.

The findings are published in the highly rankedNature Physics journal.

Facts about the research:

The sample that the researchers used is fabricated on a silicon chip and contains two key elements. The first is a superconducting circuit forming the artificial atom. The second part is a short circuit that acts as a mirror. By sending a very weak signal to the atom, researchers can measure its lifetime. At the same time, they can vary the effective distance to the mirror. This is done by changing the atomic resonance frequency, while the actual distance remains constant. By doing this you can control the distance measured in the number of wavelengths of light/microwaves. A frequency of 4.8 GHz was used in the experiment, which is close to the radio waves used in wireless networks. The experiments were performed at very low temperatures, close to absolute zero (30 mK) to ensure the atom is in its ground state at the start of the experiment.

Chemistry Of Magnetism

Magnets are well-known from the physics lessons at school, but they are hardly covered in chemistry lectures; and it is still a chemical process by means of which researchers at Karlsruhe Institute of Technology (KIT) have succeeded in controlling magnetic properties in bulk ferromagnets. While physical processes may influence the orientation of the magnetic fields, the chemical process in this case controls magnetism in carefully chosen strongly ferromagnetic material systems. The working principle used in this case is similar to the concept of lithium-ion batteries.

There are several possibilities to create or influence magnetism reversibly, by physical means. Standard methods are either to use a electromagnetic coil, for example, where a high current produces a magnetic field, but the coil continuously consumes energy. Another possibility is to polarize the ferromagnet, which means to align the magnetic structures in the material in parallel, such that an overall magnetic field is generated. No energy is required for maintaining this magnetic field, but it is permanent and cannot easily be removed. Another option is the magnetoelectric coupling, where an electric field is used to induce magnetism; however, this mechanism is often limited to the top monolayer of atoms of the crystal lattice only. Hence, results in a minimal change in the magnetization.

The newly developed chemical control of magnetism at KIT offers a unique approach that is beyond the concepts that are explained above: The process influences the bulk material, not only the surface, and it is reversible, which means that it can be undone. The distinct magnetic states (magnetic/non-magnetic) are non volatile, which offer the major novelty that the different magnetic states -- unlike the electromagnetic coil -- can be maintained without requiring a continuous flow of current and consumption of energy.

"Thousands of charge-discharge cycles of lithium-ion batteries used in mobile phones, for instance, show that electrochemical processes can be highly reversible. This led us to the idea to exploit similar structures such as the lithium-ion batteries," says Subho Dasgupta of the KIT Institute of Nanotechnology. When charging and dis-charging a lithium-ion accumulator, the ions migrate from one electrode to the other and intercalate into the electrode.

The team of scientists working with Dasgupta has now produced a lithium-ion accumulator, in which one electrode is made of maghemite, a ferromagnetic iron oxide (γ-Fe2O3), and the other electrode consists of pure lithium metal. Experiments revealed that lithium ion intercalation in maghemite reduces its magnetization at room temperature. By the specific control of the lithium ions, i.e. by charging and discharging the accumulator, magnetization of maghemite can be controlled. Similar to conventional lithium-ion accumulators, this effect can be repeated.

In the experiments reported, the researchers reached a variation of magnetization by up to 30%. In the long term, complete on-and-off magnetic switching is the goal. The scientists hope to find a process to produce a magnetic switch that works according to the same principle as an electric transistor: While the latter switches on-and-off a controlled current, the magnetic switch will switch on-and-off a strong ferromagnet.

In principle, this process may replace any applications, in which low-frequency electromagnets are used, but in this case can reach far higher energy efficiency. Research of the KIT scientists mainly aims at small magnetic actuators for use in (micro)robots or microfluidics.

Catalyst combining reactivity, selectivity could speed drug development

Chemists have long believed that inserting nitrogen -- a beneficial ingredient for making many pharmaceuticals and other biologically active molecules -- into a carbon-hydrogen bond requires a trade-off between catalyst reactivity and selectivity. But a new manganese-based catalyst developed by University of Illinois chemists has given researchers both in one efficient, lower-cost package.

Led by Illinois chemistry professor M. Christina White, the research team published its work in the journal Nature Chemistry. The catalyst will be available commercially this fall from Sigma-Aldrich (product number 799688).

"Nitrogen is ubiquitous in pharmaceuticals and molecules that come from nature that have very potent biological activities," White said. "The reaction we report allows chemists to take natural products and drug candidates containing alcohols and convert a carbon-hydrogen bond, three carbons away from the alcohol, to a nitrogen. Reactions that convert carbon-hydrogen bonds to carbon-nitrogen bonds could transform the solubility or biological properties of a molecule and enable accelerated drug discovery."

Catalysts for these types of reactions based on precious metals, such as rhodium, are reactive but not very selective, which means they could react in places other than the target. Iron-based catalysts, a past achievement of White's lab, are highly selective, precisely inserting the nitrogen, but are less reactive, only reacting with weaker types of bonds.

"It is commonly accepted that reactivity and selectivity will be inversely correlated, particularly when it comes to difficult transformations like carbon-hydrogen bond functionalization," White said. "It's like the difference between using a powerwasher and using a dentist's water pick. As you become more selective, more targeted, you may become less powerful. As you get more forceful and powerful, you lose the ability to be fine-tuned.

"We have discovered a catalyst that challenges this reactivity-selectivity paradigm," White said.

Although precious metals have been long revered for their predictable and controlled chemical reactivity, White's group explores the properties of metals found abundantly in Earth's crust, which are less-documented and considered difficult to tame. After considering the distinct mechanisms of both rhodium-based catalysts and iron-based catalysts, the researchers hypothesized that manganese may fall somewhere in the middle, leading to a blending of reactivity and selectivity. However, what they found instead was that the manganese-based catalyst was very reactive -- even more than rhodium -- while maintaining the high degree of selectivity found in iron catalysts.

"What makes this catalyst really special is that it takes the best parts of the two catalyst families that existed and it combines them into one," said graduate student Jennifer Griffin, a co-first author of the paper along with graduate student Shauna Paradine, now a postdoctoral researcher at Harvard University. "I've always thought of reactivity and selectivity in carbon-hydrogen catalysis as two mutually exclusive properties. Now, by looking at these different metals, we find that it doesn't have to be separate. You can have both."

Manganese also holds several advantages over rhodium and other precious metals, the researchers said. It is 10 million times more abundant than rhodium, so using it for large-scale pharmaceutical production is much more cost-effective. In addition, manganese is much less toxic. It is found in enzymes throughout the body and is used as an ingredient in multivitamins. This suggests that any pharmaceuticals or compounds made with the catalyst can have higher concentrations of the catalyst left in it, with less need for costly and lengthy purification.

"It really showcases the importance of exploring these types of metals in hopes of replacing precious metals that are more expensive," Griffin said. "It's exciting, looking forward to what other kinds of catalysts can be developed for other types of processes."

The researchers hope that the combination of high reactivity and high selectivity will be a boon to other chemists working to identify and synthesize new drug candidates. A subtle tweak in the molecule's structure or functionality by adding nitrogen or another functional group in a position that wasn't accessible before could dramatically change the way that molecule works in the body by affecting how it interacts with other molecules or its solubility.

"In the area of medicinal chemistry, you can image that with a very selective, reactive catalyst you can put nitrogen into various sites on a molecule, which opens up a whole new area of functionality to explore," said Jinpeng Zhao, a graduate student and co-author of the paper. "It changes the way people can modify bioactive molecules and gives new possibilities of adding function to molecules found in nature."

For example, White's group demonstrated its ability to alter drug candidates by chemically modifying a potential antibiotic molecule, dihydroplueromutilone, using a combination of its previously developed iron catalyst to install oxygen and the new manganese catalyst to install nitrogen.

The researchers will continue to explore earth metals for catalyzing other reactions at carbon-hydrogen bonds, opening the door to even more avenues of drug development. They also will explore other manganese-based catalyst systems to develop intermolecular reactions that do not rely on having a nearby alcohol group.

"Ultimately our goal is to develop a suite of highly reactive and selective catalysts that enable you to precisely add oxygen, nitrogen and carbon to every type of carbon-hydrogen bond in a complex molecule setting," White said.

A new study reveals that the bacteria can eliminate a liquid’s resistance to flow

   E. coli, illustrated here, use their tail-like flagella to swim. A new study reveals that the bacteria’s synchronized swimming can eliminate a liquid’s resistance to flow  
Water flows best when it’s chock-full of synchronized-swimming bacteria, a new experiment finds.
It may appear that water flows easily. After all, a stream of it flows a lot faster than, say, a stream of honey. But water doesn’t flow nearly as fast as liquid helium. Such a frigid liquid flows with almost no resistance. Indeed, it is said to have zero viscosity. (Viscosity is a measure of a fluid’s resistance to stress. It corresponds to the idea of how “thick” a liquid is.)
But now, by coaxing billions of cells to work together, researchers have made a small sample of a bacteria-laden water solution show no resistance to flow.
“The results are pretty compelling,” says Raymond Goldstein. He is a physicist at the University of Cambridge in England. The new study, he says, demonstrates that the motion of microbes can drive the large-scale behavior of liquids.
The new finding appears in the July 10 Physical Review Letters. Physicists Héctor Matías López and Harold Auradou at Paris-Sud University and their colleagues authored the new paper.
These researchers started with a small cup filled with water, nutrients and E. coli bacteria. There were enough nutrients to fuel the swimming of bacteria, but not enough energy to allow the microbes to divide. Then the physicists dipped a cylindrical probe into the cup. They slowly rotated the cup and measured the force of the twist, or torque, exerted by the solution on the probe.
A viscous fluid like honey would tug on and spin the probe. Water also would tug on the probe, just not as much. When infused with a strain of very active E. coli, however, the water solution exerted no torque on the probe. That indicates zero viscosity. In some trials, the viscosity actually became negative: The cup rotated counterclockwise. But the solution exerted a clockwise torque on the probe.
Before the cup spun, the bacteria had been swimming about randomly, Auradou says. But theoretical studies suggest that once the liquid starts to flow, the E. coli coordinate their motion. As the rod-shaped bacteria swim, they push water in front and behind themselves. Liquid fills in from the sides. That nudges neighboring bacteria closer together and causes them to line up and swim in a similar direction. The bacteria’s collective pushing increases the speed at which adjacent layers of water can rush past each other. That gives the solution a more efficient — and less viscous — flow.
The new finding may be especially useful in the lab. Tiny amounts of fluid can be difficult to analyze because samples can get stuck in micro-size passageways. Bacteria may help by ensuring that scientists can measure every last drop.
 

New crystal captures carbon from the air, even in the presence of water

A new material with micropores might be a way to fight climate change. Scientists have created crystals that capture carbon dioxide much more efficiently than previously known materials, even in the presence of water. The research was recently published in a report in the scientific journal Science.
One way to mitigate climate change could be to capture carbon dioxide (CO2) from the air. So far this has been difficult, since the presence of water prevents the adsorption of CO2. Complete dehydration is a costly process. Scientists have now created a stable and recyclable material, where the micropores within the crystal have different adsorption sites for carbon dioxide and water.
"As far as I know this is the first material that captures CO2 in an efficient way in the presence of humidity. In other cases there is competition between water and carbon dioxide and water usually wins. This material adsorbs both, but the CO2 uptake is enormous," says Osamu Terasaki, Professor at the Department of Materials and Environmental Chemistry at Stockholm University.
The new material is called SGU-29, named after Sogang University in Korea, and is the result of international cooperation. It is a copper silicate crystal. The material could be used for capturing carbon dioxide from the atmosphere, and especially to clean emissions.
"CO2 is always produced with moisture, and now we can capture CO2 from humid gases. Combined with other systems that are being developed, the waste carbon can be used for new valuable compounds. People are working very hard and I think we will be able to do this within five years. The most difficult part is to capture carbon dioxide, and we have a solution for that now," says Osamu Terasaki.