Hot Electrons Move Faster Than Expected

Ultrafast Motion of Electrons

A new research has given rise to solid-state devices which tend to utilise excited electrons. Engineers and scientists at Caltech have for the first time, been in a position of observing directly the ultrafast motion of electrons instantly after they have been excited by a laser. It was observed that these electrons tend to diffuse in their surroundings quickly and beyond than earlier anticipated.

This performance called as `super-diffusion has been hypothesized though not seen before. A team headed by Marco Bernardi of Caltech and the late Ahmed Zewail had documented the motion of electrons by utilising microscope which had captured the images with a shutter speed of a trillionth of a second at a nanometer-scale spatial resolution and their discoveries had appeared in a study published on May 11 in Nature Communications.

 The excited electrons had displayed a diffusion rate of 1,000 times higher than earlier excitation. Though the phenomenon had lasted only for a few hundred trillionths of a second, it had provided the possibility for operation of hot electrons in this fast system in transporting energy and charge in novel devices.

Assistant professor of applied physics and materials science in Caltech’s Division of Engineering and Applied Science, Bernardi had informed that their work portrayed the presence of fast transient which tends to last for a few hundred picoseconds at the time when electrons move quicker than their speed of room temperature, indicating that they can cover longer distance in a given period of time when operated with the help of lasers.

Ultrafast Imaging Technology

He further added that this non-equilibrium behaviour could be employed in novel electronic, optoelectronic as well as renewable energy devices together with uncovering new fundamental physics. Nobel Laureate Ahmed Zewail, the Linus Pauling Professor of Chemistry, professor of physics as well as the director of the Physical Biology Centre for Ultrafast Science and Technology at Caltech, colleague of Bernardi had passed away on 2nd August 2016.

The research had been possible by scanning ultrafast electron microscopy, which is an ultrafast imaging technology initiated by Zewail, with the potential of creating images with picosecond time with nanometer spatial resolutions. The theory and computer models had been developed by Bernardi which clarified the tentative results as an indicator of super-diffusion.

Bernandi has plans of continuing the research by trying to answer the fundamental questions regarding the excited electrons, like how they equilibrate among themselves as well as with atomic vibrations in material, together with applied ones like how hot electrons could increase the efficiency of energy conversion devices such as solar cells and LEDs.

Super Diffusion of Excited Carriers in Semiconductors

The paper has been entitled `Super Diffusion of Excited Carriers in Semiconductors’. Co-authors comprise of former postdoc Ebrahim Najafi of Caltech, who is said to be the main author of the paper and a former graduate student, Vsevolod Ivanov. The research has been supported by the National Science foundation, together with the Air Force Office of Scientific Research, the Gordon and Betty Moor Foundation as well as the Caltech-Gwangju Institute of Science and Technology – GIST, program.

Laying the Groundwork for Longer Battery Life

Batteries with Long Life – Interact with Technology

Some of the common complaints regarding cell phone or the laptop are regarding the battery life which tends to turn off when needed the most. We are inclined to rely on technology which is an integral part of our life and find it difficult to do anything without it.

 We would find it extremely difficult to cope up with our life even for a short period of time without our cell phone which tends to connect us with the external world. The faculty from Drexel’s Department of Materials Science and Engineering have discovered this topic in a latest invited article in Nature Energy – `Perspective’. Batteries having long life and tend to charge instantly could change how we interact with our technology.

Anne Steven Assistant Professor Ekaterina Pomerantseva together with Distinguished University and Charles T. as well as Ruth M. Bach Chair Professor Yury Gogotsi suggested that the next generation batteries have been developed by combining different two-dimensional 2D materials in heterostructured electrodes and would immensely enhance battery life and charge storage potentials, thus changing the technology setting. The term `2D’ materials is utilised in describing materials which tend to be developed in single layer, like a sheet of paper which is only one or many atoms thick.

2D Heterostuctured Electrodes

These exceptional materials have started portraying amazing potentials for different properties which could be applied to a wide selection of applications. The most frequently known 2D materials are said to be graphene together with various graphene modification, transition metal dischalcogenides – TMDCs, transition metal oxides –TMOs together with transition metal carbide/nitrides – MXenes.

Individually, these material families tend to display definite benefits for energy storage applications though simultaneously tend to have some shortcomings. Pomerantseva had commented that they suggest that in order to eradicate the shortcomings while maintaining most of the benefits of these opposing 2D materials is in creating what is known as 2D heterostructed electrodes composed of interchanging layers of various 2D materials which tend to portray various functionalities.

The single layer structure of 2D materials is for the most part valuable for the purpose of energy storage properties since these thin materials tend to have a great surface range that enables quick diffusion of ions from an electrolyte, which is a liquid utilised in transporting ions between two electrodes. This quick movement of ions on the surface permits a battery to charge immediately. Besides this the 2D material also makes provision for a denser packing of ions between the layers that leads to the battery stocking the charge for a longer period.

Contrary Chemical Reaction

Though there is an opportunity that the solvent utilised in the electrolyte tends to have the possibility of causing a contrary chemical reaction with the electrode in the battery resulting in reduced battery performance, the ability of 2D materials for enhanced battery performance tends to outweigh the potential challenges.

In order to build these 2D heterostructures a parallel orientation or interface of layers of various 2D materials is essential. Gogotsi has informed that the interface of materials in this way tends to optimize their unique properties. For instance, on combining various layers of TTMO together with graphene, a high capacity of oxide as well as high electronic conductivity of carbon could be attained in the resulting 2D heterostructure which could lead to a battery having high energy together with high power.

There is a possibility of modifying the 2D heterostructures still further by integrating different types of inorganic ions, organic molecules and also polymers, which are known as species between the layers. This integration of these interlayer species could lead to various developments in electrochemical properties. The interlayer species could extend the interlayer spacing enabling additional electrochemically cycling ions in being incorporated between the layers which could lead to a higher capacity which in turn could lead to energy density of the batteries.

Insertion/Extraction

Moreover due to the interactions between the layers as well as the interlayer species, the structural stability of the electrodes through multiple cycles of ions is said to go through insertions and extraction which can be enhanced. Should the interlayer species be charged, their presence between the layers could disturb the diffusion of electrochemically cycled ion inclusive of the acceleration of the diffusion that tends to lead to batteries with better power.

Utilising 2D heterostructured electrodes with suitably selected interlayer species seem to have abundant promise in developing a battery which would not only charge quickly but also hold an individual charge for a longer period and will also tend to last longer over several charge and discharge cycles.

 Pomerantseva had informed that if such a battery is utilised in powering a car, it would be capable of greater driving range before the need of a re-charge, and the re-charge process would take a short duration of time. Moreover the owner of the car would possibly desire to buy a new car well before the light indicating that the battery required to be replaced is illuminated.

L2 vs. L3 cache: What’s the Difference?

The cache is a special buffer memory that is located between the memory and the processor.

So that the processor does not have to get every program command from the slow memory individually, a whole command block or data block is loaded into the cache. The probability that the subsequent program instructions are in the cache is relatively high. Only when all program instructions have been executed or a jump command to a jump address outside the cache, the processor must access the memory again. Therefore, the cache should be as large as possible so that the processor can run the program instructions one after the other without waiting.

Typically, processors work with multi-level caches that are different in size and fast. The closer the cache is to the computing core, the faster it works.

Inclusive cache and exclusive cache

With the multicore processors the terms inclusive and exclusive cache came up. Inclusive cache means that data in the L1 cache is also present in the L2 and L3 cache. This makes data consistency between the cores more secure. Compared to the exclusive cache, some storage capacity is given away because the data is redundant in the caches of several CPU cores.

Exclusive cache means that the cache is available to a processor core exclusively, that is, for it alone. It does not have to share the cache with another core. A disadvantage of this is that several processor cores can then exchange data with one another only by way of a detour.

L1 cache / first-level cache

As a rule, the L1 cache is not particularly large. For reasons of space it moves in the order of 16 to 64 kByte. Usually, the memory area for commands and data is separated from each other. The importance of the L1 cache increases with the higher CPU speed.

In the L1 cache, the most frequently used commands and data are buffered so that as few accesses as possible to the slow memory are required. This cache avoids delays in the data transfer and helps to optimally utilize the CPU.

L2 cache / second-level cache

In the L2 cache, the data of the working memory (RAM) is buffered.

The processor manufacturers supply the different market segments with specially modified processors via the size of the L2 cache. The choice between a processor with more clock speed or a larger L2 cache can be answered in a simplified manner as follows: With a higher clock, individual programs, especially with high arithmetic requirements, run faster. As soon as several programs run at the same time, a larger cache is an advantage. Typically, normal desktop computers with a processor that has a large cache are better served than with a processor that has a high clock rate.

When the memory controller was shifted from the chipset into the processor and the processor was able to access memory much faster, the importance of the L2 cache decreased. While the size of the L2 cache has decreased, the L3 cache has been properly upgraded.

L3 cache / third-level cache

As a rule, multicore processors use an integrated L3 cache. With the L3 cache, the Cache Koheranz protocol of Multicore processors can work much faster. This protocol compares the caches of all cores to maintain data consistency. The L3 cache thus has less functions of a cache, but is intended to simplify and speed up the cache coherency protocol and the data exchange between the cores.

As modern processors now contain several data cores - so-called cores - the manufacturers have already donated a third cache, the L3 cache, to these multi-core processors. All processor cores work together, which is particularly beneficial in parallel processing. This allows data shared by different CPU cores to be retrieved from the fast L3 cache. Without it, these data would always come from the slow main memory. In addition, the L3 cache also facilitates data management with multiple CPU cores and caches (data coherency).

Google Leak Reveals Pixel 2 'Shape Change'

Google Pixel 2: Code names indicate pixel successors and a new Nexus

Google, the internet giant is working on pixel 2. Now for the first time the codenames of the new Google smartphones have been revealed. So the pixel 2 internally to the name "Walleye" and the pixel XL 2 to the name "Muskie". A third device with the code name "Taimen" provides for speculation. Does Google plan a new Nexus smartphone?Will Google work on three new smartphones for the year 2017? According to media reports, the company is developing the Google Pixel and the Google Pixel XL as codename "Walleye" and "Muskie". "Walleye" is the smaller Google pixel 2, "Muskie" is the Pixel XL 2, reports the usually well-informed US blog Android Police. A reference to "Walleye" has already been discovered in the Android source code.
According to the web page "Droid Life", "Taimen" is said to be another new Google smartphone, which will show a larger screen than Pixel XL 2 to the informer of the website. Possibly, the display will measure six inches in the diagonal. According to Droid Life, "Taimen" is not likely to be marketed under the "Google Pixel" brand. So far the information here is very daring.

This is what the code names mean

What do the code names "Walleye", "Muskie" and "Taimen" mean? Traditionally, Google is designing new devices internally for fish and / or fish species, which was earlier in the Nexus smartphones. So the Nexus 6 was called "Shamu" because of its size. A homage to the killer whale from the SeaWorld shows.

The Nexus 5X was developed under the codename "Bullhead", the English term for catwels. The first pixel devices internally on Google called "Sailfish" (fanfish) and "Marlin" (spearfish). "Walleye" and "Muskie" are also fish species. "Walleye" is the English name for glass eye bass. Taimen, on the other hand, is a very large species of salmon.

Google Pixel 2 - Release, price and rumors

Google will unveil 2017 presumably successor for its pixel smartphones. In the net, first rumors circulate to a supposed Google pixel 2. The summarize of what Mono-live.com knew so far about the new Google smartphones.

In 2016 Google introduced its Nexus series and replaced the device family with the new product range Google Pixel. With the five-inch Google pixel and the 5.5-inch Google Pixel XL, the manufacturer launched two smartphones under the new name on the market. Both devices, however, did not differ from the size.

This year, Google will probably present successors for the pixel devices. In the following you will learn what Mono-live.com knew about the Google Pixel 2 and the Pixel XL 2.

Release: When will the new Google smartphones appear?

There is not yet a release date for Google Pixel 2 and Pixel XL 2. The first pixel smartphones appeared on 4 October 2016. It is therefore to be expected that Google will bring the successors in October 2017 on the market.

Price: How expensive are the new pixel smartphones

Also unclear is how expensive the new Google smartphones will be. Both the Google pixel and the pixel XL were anything but favorable. The prices began at 759 and 899 euros respectively. Currently there are rumors that Google will release a more affordable pixel model this year. However, this remains to be seen.

Harvard Scientists Use Simple Materials to Create Semi Soft Robots

Biologically Inspired Soft Robots

George Whitesides towards the start of the decade had assisted in rewriting the rules of what a machine could be with the improvement of biologically inspired soft robots and is now ready to rewrite it once again with the support of some plastic drinking straws. Whitesides together with Alex Nemiroski a former postdoctoral fellow in Harvard lab of Whitesides had been encouraged by arthropod insects and spiders and have developed a kind of semi-soft robot which is capable of standing and walking.

 The team has also developed a robotic water strider with the skill of pushing itself along the liquid surface. The robots have been defined in a recent paper published in the journal Soft Robotics. The new robots unlike the earlier generations of soft robots that could stand and walk uncomfortably by filling air chambers in their bodies are designed to be extremely quicker.

The researchers are expecting that the robots would finally be utilised in search operations, even though practical applications seems to be far away, in an event of natural calamities or in conflict zones. The Woodford L and Ann A. Flowers University Professor at Harvard, Whitesides stated that if one looks around the world, there are plenty of things like spiders and insects that are very agile.

Flexible Organisms on Planet

They can move rapidly, climb on various items and are capable of doing things which huge hard robot are unable to do due to their weight and form factor. They are among the most flexible organisms on the planet and the question was how we can build something like that.

The answer from Nemiroski was that it came in the form of one’s average drinking straw. He informed that it had all began from an observation which George had made that polypropylene tubes have an excellent strength-to-weight ratio. This gave rise to developing something which has more structural support than virtuously soft robots tend to have.

 That has been the building block and then they got inspiration from arthropods to figure out how to make a joint and how to use the tubes as an exoskeleton. After that there was a question of how far one’s imagination can go and once you have a Lego brick, what type of castle can one build with it. He added that what they built was a surprisingly simple joint.

Whitesides, with Nemiroski had started by cutting a notch in the straws enabling them to bend. The scientists then inserted short lengths of tubing which on inflation forced the joints to spread. A rubber tendon linked on either side then caused the joint to retract when the tubing flattened.

Microcontroller Run By Arduino

The team equipped with the simple concept, built a one-legged robot capable of crawling and moved up in intricacy as they added a second and later a third leg enabling the robot to stand on its own. Nemiroski stated that with every new level of system complexity they would have to go back to the original joint, making modifications in building it to be capable of exerting more force or to be capable of supporting the weight of larger robots.

Eventually when they graduated to six- or eight- legged arthrobots, enabling them to walk, became a challenge from the point of view of programming. For instance it was viewed at the way ants and spiders sequence the motion of their limbs and then attempted to figure out if the aspects of these motions were applicable to what they were doing or if the need for developing their own kind of walking tailored to these specific kinds of joints.

 Though Nemiroski together with his colleagues accomplished in directing simple robots by hand, by utilising syringes, they resorted to computers in controlling the sequencing of their limbs since the designs amplified by way of complexity. He informed that they had put together a microcontroller run by Arduino which tends to utilise valve together with a central compressor that enabled them the freedom to evolve their gait swiftly.

Motion of Joint – Binary – Simplicity of Valving System

Although Nemiroski along with his colleagues had been skilful in reproducing the distinctive `triangle’ gait of ants utilising their six-legged robot, imitating a spider-like gait, proved to be far riskier. He added that a spider has the tendency of modulating the speed which it extends and contracts its joints to carefully time which limbs are moving forward and backward at any point.

Nemiroski further added that however in our case, the motion of the joint is binary owing to the simplicity of our valving system. You either switch the valve to the pressure source to inflate the balloon in the joint and extend the limb or switch the valve to atmosphere in order to deflate the joint and thus retract the limb. In the case of the eight-legged robot, the gait compatible had to be developed with binary motion of the joints.

Though it was not a brand new gait but they could not accurately duplicate how a spider tends to move for this robot. Nemiroski stated that developing a scheme which can modify the swiftness of actuation of legs would be a useful objective for future exploration and would need programmable control over the flow rate supplied to each joint.

Academic Prototypes

Whitesides is of the belief that the techniques utilised in their development especially the use of daily off-the-shelf stuff can point the way toward future innovation, though it would take years before the robots make their way in the real world applications.

He stated that he does not see any reason to reinvent wheels and if one looks at drinking straws, they can make them all, effectively at zero cost together with great strength and so why not use them? They are academic prototypes and hence they tend to be very light weight though it would be quite easy to imagine building these with a lightweight operational polymer which could hold a considerable weight.

Nemiroski added that what is really attractive here is the simplicity and this is something George had been championing for some time and something which he grew to appreciate deeply while in his lab.