Scientists Just Discovered Plastic-Eating Bacteria That Can Break Down PET.

     
  We manufacture over 300 million tonnes of plastics each year for use in everything from packaging to clothing. Their resilience is great when you want a product to last. But once discarded, plastics linger in the environment, littering streets, fields and oceans alike. Every corner of our planet has been blighted by our addiction to plastic. But now we may have some help to clean up the mess in the form of bacteria that have been found slowly munching away on discarded bottles in the sludge of a recycling centre.

Plastics are polymers, long thin molecules made of repeating (monomer) building blocks. These are cross-linked to one another to build a durable, malleable mesh. Most plastics are made from carbon-based monomers, so in theory they are a good source of food for microorganisms.

But unlike natural polymers (such as cellulose in plants) plastics aren’t generally biodegradable. Bacteria and fungi co-evolved with natural materials, all the while coming up with new biochemical methods to harness the resources from dead matter.

But plastics have only been around for about 70 years. So microorganisms simply haven’t had much time to evolve the necessary biochemical tool kit to latch onto the plastic fibres, break them up into the constituent parts and then utilise the resulting chemicals as a source of energy and carbon that they need to grow.

Enzyme innovation

Now a team at Kyoto University has, by rummaging around in piles of waste, found a plastic munching microbe. After five years of searching through 250 samples, they isolated a bacteria that could live on poly(ethylene terephthalate) (PET), a common plastic used in bottles and clothing. They named the new species of bacteria Ideonella sakaiensis.

You may think this is the rerun of an old story, as plastic-eating microbes have already been touted as saviours of the planet. But there are several important differences here.

First, previous reports were of tricky-to-cultivate fungi, where in this case the microbe is easily grown. The researchers more or less left the PET in a warm jar with the bacterial culture and some other nutrients, and a few weeks later all the plastic was gone.

Second - and the real innovation - is that the team has identified the enzymes that Ideonella sakaiensis uses to breakdown the PET. All living things contain enzymes that they use to speed up necessary chemical reactions. Some enzymes help digest our food, dismantling it into useful building blocks. Without the necessary enzymes the body can’t access certain sources of food.

For example, people who are lactose intolerant don’t have the enzyme that breaks down the lactose sugar found in dairy produce. And no human can digest cellulose, while some microbes can. Ideonella sakaiensis seems to have evolved an efficient enzyme that the bacteria produces when it is in an environment that is rich in PET.

The Kyoto researchers identified the gene in the bacteria’s DNA that is responsible for the PET-digesting enzyme. They then were able to manufacture more of the enzyme and then demonstrate that PET could be broken down with the enzyme alone.

First real recycling

This opens a whole new approach to plastic recycling and decontamination. At present, most plastic bottles are not truly recycled. Instead they are melted and reformed into other hard plastic products. Packaging companies typically prefer freshly made 'virgin' plastics that are created from chemical starting materials that are usually derived from oil.

The PET-digesting enzymes offer a way to truly recycle plastic. They could be added to vats of waste, breaking all the bottles or other plastic items down into into easy-to-handle chemicals. These could then be used to make fresh plastics, producing a true recycling system.

Manufactured enzymes are already used to great effect in a wide range of everyday items. Biological washing powders contain enzymes that digest fatty stains. The enzymes known as rennet that are used to harden cheese once came from calfs’ intestines but are now manufactured using genetically engineered bacteria. Maybe we can now use a similar manufacturing method to clean up our mess.

Plastic recycling: Plastic changing to oil machine (BP-2000N/5000N).

    

4D electron microscopy images charge density at sub-angstrom scales.

 Scanning transmission electron microscopy (STEM) can be used to detect electric charge density as well as image atoms. This new advance comes from researchers at the University of California, Irvine, who used the technique to show how interfacing a ferroelectric oxide with an insulating oxide can produce an electron-rich region in between the two materials. The work is an important step towards understanding and engineering material structures with strongly-correlated electrons.

Nearly all the physical properties of materials are determined by how electron charge is rearranged between nuclei when atoms aggregate together. Being able to directly visualize how electrons are distributed is therefore important. Compared to other diffraction methods, aberration-corrected STEM (AC-STEM) allows for atomic-scale imaging of a sample using an electron beam, or probe, focused to about half an angstrom in size. When electrons pass through the sample, they interact with the internal electric field in their path through the Lorentz force. This changes the beam’s momentum, which can then be measured by diffraction.

A team led by Xiaoqing Pan has now used a state-of-the-art AC-STEM and a high-speed pixelated electron camera to measure this change and delineate the electric field in a
local region of the sample and so derive the electric charge density in this region. The researchers did their experiments on a composite material made from the ferroelectric oxide bismuth ferrite (BiFeO3) and the insulating oxide strontium titanite (SrTiO3).  

“We can raster scan a 2D area of the sample using our electron camera and acquire a diffraction pattern at each point on the sample,” explains Pan. “The nice thing is that our detector can acquire 4D STEM images with 512 x 512 pixels at a speed of greater than 300 frames per second.”

Visualizing charge transfer

The researchers say they used their technique to visualize the mechanism of charge transfer between the BiFeO3 and  SrTiO3. “We did this by simply comparing the images we obtained from the two materials,” says Pan. “With the high resolution to determine the local charge distribution, we can see how the positive ionic cores and electrons are separated in BiFeO3.

“By then imaging the interface between the BiFeO3 and SrTiO3, we observe that an electric field from the former can leak through the interface towards the first few layers in the latter, causing the charge in SrTiO3 to accumulate at the interface between the two oxides.”

Electron images achieve record-breaking resolution.

Electron ptychography reveals sub-angstrom features in 2D molybdenum disulphide (Nature 559 343–349)

A new electron microscopy technique that achieves far better resolution than ever before, while also minimizing potential electron damage to the sample, has been unveiled by researchers in the US. The team presented images of the 2D material molybdenum sulphide that show unprecedented atomic-level detail, and they are confident that the technique could also be exploited in a range of applications where traditional electron microscopy has proved difficult.

Electron microscopes are valued for their increased resolution over visible light microscopes, thanks to the much smaller wavelength of electrons relative to photons. However, the resolution of these instruments is constrained by small aberrations in electron lenses, which limit the size of the aperture and make it difficult to focus the electron beam. Electron microscopists have so far achieved resolutions of around 0.5 Å (0.05 nm) in bulk materials – generally good enough to see individual atoms – by combining sophisticated and expensive aberration-correctors with shorter-wavelength, higher-flux electron beams that increase the signal-to-noise ratio.

Damage limitation

However, these shorter-wavelength, higher-energy electrons can do significant damage to samples, especially at high electron fluxes. “There are two damage mechanisms from electrons,” explains David Muller of Cornell University in New York. “One of them is that you ionize the sample and you kick electrons off. The other is that the electron transfers so much momentum to the nucleus that it kicks it off its lattice site and breaks bonds. The lower your beam energy the less you’re going to knock things around.”

These damage mechanisms have prevented the attainment of sub-angstrom resolutions in delicate samples such as 2D materials, which can rapidly be obliterated by a powerful electron beam: “If I have a 2D material and I knock off one atom every second, I’m going to notice almost immediately that it’s looking like Swiss cheese,” says Muller.

Muller and colleagues solved the problem by exploiting a technique called ptychography, which was first conceived for X-ray crystallography almost 50 years ago but in principle is equally applicable to imaging with electrons. The idea is to record the exact diffraction pattern built up on the detector from every point in the sample, and to study how this changes across the sample. From this information, it is possible to reconstruct the phase of the matter wave diffracted by the sample and to work out the shape of the diffracting object – in other words, the pattern of atoms.

the technique not only records the beam intensity, but also uses it to reconstruct the underlying quantum wavefunction, it can extract much more information per electron – and so potentially requires far fewer electrons. But its use in electron microscopy has so far been hampered by the formidable requirements placed on the detector. This is because ptychography requires the phase of the wavefunction to be measured equally precisely in both dark and light spots, but in electron diffraction experiments the high-angle diffraction peaks are extremely dim compared to the signal from the main beam.

To address this problem, Muller and colleagues have developed a detector capable of recording single electrons, even though some pixels are subjected to an electron flux a million times greater than others. “Imagine I had a camera, and I took a picture of you and the Sun shining from behind you,” says Muller. “Our detector would be able to image all the sunspots on the surface of the Sun and all the details of your face in the shadow.” This new instrument, which the scientists have dubbed the electron microscope pixel array detector (EMPAD), allowed them to perform full electron ptychography for the first time.

Imaging at the atomic scale

The researchers demonstrated their approach by imaging the 2D material molybdenum disulphide. Despite using electrons of only 80 keV – less than half the 200 keV often used to image bulk samples – the researchers achieved record-breaking resolution of 0.39 Å. They were able to clearly discern features that were unclear in images produced using other techniques, such as a sulphur monovacancy – a random defect in which one of two sulphur atoms in the MoS2 lattice structure is missing but the other is still present.

The researchers are now looking at other types of systems, such as biological samples. “Biological materials are extremely sensitive to radiation,” says Muller, “so the resolution of biological systems in limited by the number of electrons you can put on the sample.” They are also studying tiny strains in catalyst nanoparticles, which are crucial for their chemical activity.

John Rodenburg of the University of Sheffield, one of the inventors of electron ptychography, is impressed. “Many years ago we showed that if you had a bad electron lens, you could improve on it many times. This paper is the first to show that you can way surpass even a good electron lens,” he says.

Rodenburg believes the real potential of the work is in 3D imaging. “The phase is linear as you put more atoms on top of one another,” he explains. “That gives you the possibility of getting the three-dimensional structure of a material out, and that’s what X-ray ptychography is mainly used for.”

                            Thank you !!!......

NASA make a engine which travels with the speed of 99%of light

NASA engineer conceptualises engine travelling at 99% speed of light

NASA engineer David Burns has recently conceptualized an engine which can theoretically accelerate to 99 percent of the speed of light - without a propellent

Updated On: October 18, 2019 17:33 IST

In a world-changing breakthrough in physics, NASA engineer David Burns has recently conceptualized an engine which can theoretically accelerate to 99 percent of the speed of light - all without using propellant, as per international reports. The engine named 'Helical engine'  reportedly works by exploiting the way mass can change at relativistic speeds, particularly close to the speed of light in a vacuum. Burns has published his findings in NASA Technical Reports. The paper is yet to be reviewed by experts.

Many experts have dubbed that the engine could 'violate the laws of physics'. While the concept is still in theory, Burns believes that the engine could have applications.

NASA engineer conceptualises engine travelling at 99% speed of light

NASA engineer David Burns has recently conceptualized an engine which can theoretically accelerate to 99 percent of the speed of light - without a propellent

Updated On: October 18, 2019 17:33 IST

In a world-changing breakthrough in physics, NASA engineer David Burns has recently conceptualized an engine which can theoretically accelerate to 99 percent of the speed of light - all without using propellant, as per international reports. The engine named 'Helical engine'  reportedly works by exploiting the way mass can change at relativistic speeds, particularly close to the speed of light in a vacuum. Burns has published his findings in NASA Technical Reports. The paper is yet to be reviewed by experts.

Many experts have dubbed that the engine could 'violate the laws of physics'. While the concept is still in theory, Burns believes that the engine could have applications.

READ | Chandrayaan 2 | 'Vikram Must Have Done A Hard-landing': ISRO To PTI

Helical Engine: Travels at 99% speed of light

According to reports, Burns has explained the concept of his engine as a box with a weight inside, threaded on a line, with a spring at each end bouncing the weight back and forth. He has claimed that the effect of this would be to wiggle the entire box, with the weight seeming to stand still. He states that while the box would stay in the spot wiggling if the mass of the weight were to increase in only one direction, it would generate a greater push in that direction - hence a thrust. 

Burns' model is a helical structure which theoretically makes ions move faster at one end of the loop, and slower at the other. "The engine accelerates ions confined in a loop to moderate relativistic speeds and then varies their velocity to make slight changes to their mass. The engine then moves ions back and forth along the direction of travel to produce thrust," states Burns in his paper. He added, "The engine has no moving parts other than ions traveling in a vacuum line, trapped inside electric and magnetic fields."

READ | 'ISRO Needs To Explore Fate Of Vikram Lander', Say US Experts

While his concept is theoretically possible, scientists say that practically designing such an engine is still not a reality. Burns has listed the inefficiencies of the engine and the large specifications of the design if such an engine is possible. But, in space, such an engine may be possible, states Burns. "The engine itself would be able to get to 99 percent the speed of light if you had enough time and power," he said.