Aurelia Butler

Gas accidents such as toxic gas leakage in factories, carbon monoxide leakage of boilers, or toxic gas suffocation during manhole cleaning continue to claim lives and cause injuries. Developing a sensor that can quickly detect toxic gases or biochemicals is still an important issue in public health, environmental monitoring, and military sectors. Recently, a research team at POSTECH has developed an inexpensive, ultra-compact wearable hologram sensor that immediately notifies the user of volatile gas detection.
A joint research team led by Professor Junsuk Rho of departments of mechanical and chemical engineering and Dr. Inki Kim of Department of Mechanical Engineering with Professor Young-Ki Kim and Ph.D. candidate Won-Sik Kim of Department of Chemical Engineering at POSTECH has integrated metasurface with gas-reactive liquid crystal optical modulator to develop a sensor that provides an immediate visual holographic alarm when harmful gases are detected. The findings from this study were published in Science Advances on April 7, 2021.
For those working in hazardous environments such as petrochemical plants, gas sensors are life. However, conventional gas sensing devices are not widely used due to their high cost of being made with complex machines and electronic devices. In addition, commercial gas sensors have limitations in that they are difficult to use, and have poor portability and reaction speed.
To solve these issues, the research team utilized the metasurface, well known as a future optical device known to have the invisible cloak effect through making visible objects disappear by controlling the refractive index of light. Metasurface is especially used to transmit two-way holograms or 3D video images by freely controlling light.
Using the metasurface, the research team developed a gas sensor that can float a holographic image alarm in space in just a few seconds by using the polarization control of transmitted light that transforms due to the change in orientation of liquid crystal molecules in the liquid crystal layer inside the sensor device when exposed to gas. Moreover, this gas sensor developed by the research team requires no support from external mechanical or electronic devices, unlike other conventional commercial gas sensors. The researchers used isopropyl alcohol as the target hazardous gas, known as a toxic substance that can cause stomach pain, headache, dizziness, and even leukemia.
The newly developed sensor was confirmed to detect even the minute amount of gas of about 200ppm. In an actual experiment using a board marker, a volatile gas source in our daily life, a visual holographic alarm popped up instantaneously the moment the marker was brought to the sensor.
Moreover, the research team developed a one-step nanocomposite printing method to produce this flexible and wearable gas sensor. The metasurface structure, which was previously processed on a hard substrate, was designed to enable rapid production with a single-step nanocasting process on a curved or flexible substrate.
When the flexible sensor fabricated using this method attaches like a sticker on safety glasses, it can detect gas and display a hologram alarm. It is anticipated to be integrable with glass-type AR display systems under development at Apple, Samsung, Google, and Facebook.
Going a step further, the research team is developing a high-performance environmental sensor that can display the type and concentration level of gases or biochemicals in the surroundings with a holographic alarm, and is studying optical design techniques that can encode various holographic images. If these studies are successful, they can be used to reduce accidents caused by biochemical or gas leaks.
“This newly developed ultra-compact wearable gas sensor provides a more intuitive holographic visual alarm than the conventional auditory or simple light alarms,” remarked Prof. Junsuk Rho. “It is anticipated to be especially effective in more extreme work environments where acoustic and visual noise are intense.” More

When temperatures drop below zero degrees Celsius, water turns to ice. But does everything actually freeze if you just cool it down enough? In the classical picture, matter inherently becomes solid at low temperatures. Quantum mechanics can, however, break this rule. Therefore, helium gas, for example, can become liquid at -270 degrees, but never solid under atmospheric pressure: There is no helium ice.
The same is true for the magnetic properties of materials: at sufficiently low temperatures, the magnetic moments known as ‘spins’, for example, arrange themselves in such a way that they are oriented opposite/antiparallel to their respective neighbors. One can think of this as arrows pointing alternating up and down along a chain or in a checkerboard pattern. It gets frustrating when the pattern is based on triangles: While two spins can align in opposite directions, the third is always parallel to one of them and not to the other — no matter how you turn it.
For this problem, quantum mechanics suggests the solution that the orientation and bond of two spins are not rigid, but the spins fluctuate. The state formed is called a quantum spin liquid in which the spins constitute a quantum mechanically entangled ensemble. This idea was proposed almost fifty years ago by the American Nobel laureate Phil W. Anderson (1923-2020). After decades of research, only a handful of real materials remain in the search for this exotic state of matter. As a particularly promising “candidate” a triangular lattice in a complex organic compound was considered, in which no magnetic order with a regular up-down pattern could be observed, even at extremely low temperatures. Was this the proof that quantum spin liquids really exist?
One problem is that it is extremely challenging to measure electron spins down to such extremely low temperatures, especially along different crystal directions and in variable magnetic fields. All previous experiments have been able to probe quantum spin liquids only more or less indirectly, and their interpretation is based on certain assumptions and models. Therefore, a new method of broadband electron spin resonance spectroscopy has been developed over many years at the Institute of Physics 1 at the University of Stuttgart.
Using on-chip microwave lines, one can directly observe the properties of the spins down to a few hundredths of a degree above absolute zero. In doing so, the researchers found that the magnetic moments do not arrange themselves in the up-down pattern of a typical magnet, nor do they form a dynamic state resembling a liquid. “In fact, we observed the spins in spatially separated pairs. Thus, our experiments have shattered the dream of a quantum spin liquid for now, at least for this compound,” summarizes Prof. Martin Dressel, head of the Institute of Physics 1.
But even though the pairs did not fluctuate as hoped, this exotic ground state of matter has lost none of its fascination for the physicists. “We want to investigate whether quantum spin liquids might be detectable in other triangular lattice compounds or even in completely different systems such as honeycomb structures,” Dressel outlines the next steps. However, it could also be that such a disordered, dynamic state simply does not exist in nature. Perhaps every kind of interaction leads in one way or another to a regular arrangement if the temperature is low enough. Spins just like to pair up.
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A team of researchers from QuTech in the Netherlands reports realization of the first multi-node quantum network, connecting three quantum processors. In addition, they achieved a proof-of-principle demonstration of key quantum network protocols. Their findings mark an important milestone towards the future quantum internet and have now been published in Science.
The quantum internet
The power of the Internet is that it allows any two computers on Earth to be connected with each other, enabling applications undreamt of at the time of its creation decades ago. Today, researchers in many labs around the world are working towards first versions of a quantum internet — a network that can connect any two quantum devices, such as quantum computers or sensors, over large distances. Whereas today’s Internet distributes information in bits (that can be either 0 or 1), a future quantum internet will make use of quantum bits that can be 0 and 1 at the same time. ‘A quantum internet will open up a range of novel applications, from unhackable communication and cloud computing with complete user privacy to high-precision time-keeping,’ says Matteo Pompili, PhD student and a member of the research team. ‘And like with the Internet 40 years ago, there are probably many applications we cannot foresee right now.’
Towards ubiquitous connectivity
The first steps towards a quantum internet were taken in the past decade by linking two quantum devices that shared a direct physical link. However, being able to pass on quantum information through intermediate nodes (analogous to routers in the classical internet) is essential for creating a scalable quantum network. In addition, many promising quantum internet applications rely on entangled quantum bits, to be distributed between multiple nodes. Entanglement is a phenomenon observed at the quantum scale, fundamentally connecting particles at small and even at large distances. It provides quantum computers their enormous computational power and it is the fundamental resource for sharing quantum information over the future quantum internet. By realizing their quantum network in the lab, a team of researchers at QuTech — a collaboration between Delft University of Technology and TNO — is the first to have connected two quantum processors through an intermediate node and to have established shared entanglement between multiple stand-alone quantum processors.
Operating the quantum network
The rudimentary quantum network consists of three quantum nodes, at some distance within the same building. To make these nodes operate as a true network, the researchers had to invent a novel architecture that enables scaling beyond a single link. The middle node (called Bob) has a physical connection to both outer nodes (called Alice and Charlie), allowing entanglement links with each of these nodes to be established. Bob is equipped with an additional quantum bit that can be used as memory, allowing a previously generated quantum link to be stored while a new link is being established. After establishing the quantum links Alice-Bob and Bob-Charlie, a set of quantum operations at Bob converts these links into a quantum link Alice-Charlie. Alternatively, by performing a different set of quantum operations at Bob, entanglement between all three nodes is established. More

Inspired by the workings of a bat’s ear, Rolf Mueller, a professor of mechanical engineering at Virginia Tech, has created bio-inspired technology that determines the location of a sound’s origin.
Mueller’s development works from a simpler and more accurate model of sound location than previous approaches, which have traditionally been modeled after the human ear. His work marks the first new insight for determining sound location in 50 years.
The findings were published in Nature Machine Intelligence by Mueller and a former Ph.D. student, lead author Xiaoyan Yin.
“I have long admired bats for their uncanny ability to navigate complex natural environments based on ultrasound and suspected that the unusual mobility of the animal’s ears might have something to do with this,” said Mueller.
A new model for sound location
Bats navigate as they fly by using echolocation, determining how close an object is by continuously emitting sounds and listening to the echoes. Ultrasonic calls are emitted from the bat’s mouth or nose, bouncing off the elements of its environment and returning as an echo. They also gain information from ambient sounds. Comparing sounds to determine their origin is called the Doppler effect. More

In 2018, when Professor Laurie Santos introduced her course “Psychology and the Good Life,” a class on the science of happiness, it became the most popular in the history of Yale, attracting more than 1,200 undergraduate enrollees that first semester. An online course based on those teachings became a global phenomenon. By latest count, 3.38 million people have enrolled to take the free Coursera.org course, called “The Science of Well Being.”
But the popularity of the course posed an interesting question. Does taking the course and participating in homework assignments — which include nurturing social connections, compiling a gratitude list, and meditation — really help improve a sense of well-being?
The answer is yes, according to two new studies that measured the psychological impact on individuals who took Santos’s or a similar course. The findings suggest that free online courses that teach principles of positive psychology can enrich the lives of millions of people.
In the latest study, published April 14 in the journal PLOS ONE, researchers at Johns Hopkins University and Yale found that people who took the online “Science of Well Being” course reported a greater sense of well-being than those enrolled in another Yale Coursera course, “Introduction to Psychology.” Although learners in both classes said they experienced significant improvement in their well-being after taking the courses, those who took the “Science of Well-Being” course reported greater mental health benefits than those learning about the basics of psychology.
Unlike the psychology course, “The Science of Well Being” requires participants to do exercises known to improve psychological health, such as improving sleep patterns, developing exercise routines, and practicing meditation, the authors say. Before and after taking the course, participants answered questions designed to measure factors related to psychological health such as positive emotions, engagement, and strength of relationships.
“Knowledge is great but it isn’t enough. You also have to do the work,” said lead author David Yaden, research fellow in the Department of Psychiatry and Behavioral Sciences at Johns Hopkins.
A similar study in Health Psychology Open, conducted by researchers at Yale and the University of Bristol, surveyed people who took either a live or an online credit-bearing course based on Santos’s original class and found similar psychological benefits for enrollees.
Yaden stressed, however, that the classes are not a substitute for professional treatment for those who suffer from diagnosed mental illness. “These courses are not a panacea or replacement for psychotherapy or medication,” he said.
However, both Yaden and Santos, who co-authored the study, say the findings show that massive open online courses can provide at least modest value to millions of people at no cost.
“We wanted to know if we could scale these benefits and we can,” Santos said. “Even bringing a small mental health benefit to millions of people can have a huge value.”
Other authors of the PLOS ONE paper are Jennifer Claydon,, Meghan Bathgate, and Belinda Platt of the Yale Poorvu Center for Teaching and Learning.
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Materials provided by Yale University. Original written by Bill Hathaway. Note: Content may be edited for style and length. More

Research breakthrough in understanding how neural systems process and store information.
A team of scientists from the University of Exeter and the University of Auckland have made a breakthrough in the quest to better understand how neural systems are able to process and store information.
The researchers, including lead author Dr Kyle Wedgwood from the University of Exeter’s Living Systems Institute, have made a significant discovery in how a single cell can store electrical patterns, similar to memories.
They compared sophisticated mathematical modelling to lab-based experiments to determine how different parameters, such as how long it takes for neuronal signals to be processed and how sensitive a cell is to external signals, affect how neural systems encode information.
The research team found that a single neuron is able to select between different patterns, dependent on the properties of each individual stimulus.
The research offers a new step towards developing a greater understanding of how information is encoded and stored in the brain, which could open up fresh insights into the cause and treatment of conditions such as dementia.
The research is published in the Journal of the Royal Society Interface on Wednesday, April 14th 2021.
Dr Wedgwood, from the University of Exeter’s Living Systems Institute said: “This work highlights how mathematical analysis and wet-lab experiments can be closely integrated to shed new light on fundamental problems in neuroscience.
“That the theoretical predictions were so readily confirmed in experiments gives us great confidence in the mathematical approach as a tool for understanding how individual cells store patterns of activity. In the long run, we hope that this is the first step to a better understanding of memory formation in neural networks.”
According to Professor Krauskopf from the University of Auckland: “The research shows that a living neuron coupled to itself is able to sustain different patterns in response to a stimulus. This is an exciting first step towards understanding how groups of neurons are able to respond to external stimuli in a precise temporal manner.”
“Communication between neurons occurs over large distances. The communication delay associated with this plays an important role in shaping the overall response of a network. This insight is crucial to how neural systems encode memories, which is one of the most fundamental questions in neuroscience,” adds Professor Tsaneva form the University of Exeter’s Living Systems Institute.
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New research shows how to measure the super-short bursts of high-frequency light emitted from free electron lasers (FELs). By using the light-induced ionization itself to create a femtosecond optical shutter, the technique encodes the electric field of the FEL pulse in a visible light pulse so that it can be measured with a standard, slow, visible-light camera.
“This work has the potential to lead to a new online diagnostic for FELs, where the exact pulse shape of each light pulse can be determined. That information can help both the end-user and the accelerator scientists,” said Pamela Bowlan, Los Alamos National Laboratory’s lead researcher on the project. The paper was published April 12, 2021 in Optica. “This work also paves the way for measuring x-ray pulses or femtosecond time-resolved x-ray images.”
Free electron lasers, which are driven by kilometer-long linear accelerators, emit bursts of short-wavelength light lasting one quadrillionth of a second. As a result, they can act as strobe lights for viewing the fastest events in nature — atomic or molecular motion — and therefore promise to revolutionize our understanding of almost any kind of matter.
Measuring such a vanishingly rapid burst of ionizing radiation has previously proved challenging. But while electronics are too slow to measure these light pulses, optical effects can be essentially instantaneous. Squeezing all of the energy of a continuous laser into short pulses means that femtosecond laser pulses are extremely bright and have the ability to modify a material’s absorption or refraction, creating effectively instantaneous “optical shutters.”
This idea has been widely used for measuring visible-light femtosecond laser pulses. But the higher-frequency extreme ultraviolet light from FELs interacts with matter differently; this light is ionizing, meaning that it pulls electrons out of their atoms. The researchers showed that ionization itself can be used as a “femtosecond optical shutter” for measuring extreme ultraviolet laser pulses at 31 nanometers.
“Ionization typically changes the optical properties of a material for nanoseconds, which is 10,000 times slower than the FEL pulse duration,” Bowlan said. “But the duration of the rising edge of ionization, determined by how long it takes the electron to leave the atom, is significantly faster. This resulting change in the optical properties can act as the fast shutter needed to measure the FEL pulses.”
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Materials provided by DOE/Los Alamos National Laboratory. Note: Content may be edited for style and length. More