Articles from January 2020

Scientists have long speculated that at the heart of a gas giant, the laws of material physics undergo some radical changes. In these kinds of extreme pressure environments, hydrogen gas is compressed to the point that it actually becomes a metal. For years, scientists have been looking for a way to create metallic hydrogen synthetically because of the endless applications it would offer. At present, the only known way to do this is to compress hydrogen atoms using a diamond anvil until they change their state. And after decades of attempts (and 80 years since it was first theorized), a team of French scientists may have finally created metallic hydrogen in a laboratory setting. While there is plenty of skepticism, there are many in scientific community who believe this latest claim could be true. The study which described their experiment, titled Observation of a first order phase transition to metal hydrogen near 425 GPa, recently appeared on the arXiv preprint server.

The team consisted of Paul Dumas, Paul Loubeyre, and Florent Occelli, three researchers from the Division of Military applications (DAM) at the French Alternative Energies and Atomic Energy Commission and the Synchrotron SOLEIL research facility.

As they indicate in their study, it is indisputable that “metal hydrogen should exist” thanks to the rules of quantum confinement. Specifically, they indicate that if the electrons of any material are restricted enough in their motion, what is known as the “band gap closure” will eventually take place.

In short, any insulator material (like oxygen) should be able to make become a conductive metal if it is pressurized enough. They also explain how two advances made their experiment possible. The first has to do with the diamond anvil setup they used, where the diamond tips were toroid-shaped – a torus with a hole in the middle (like a donut) – instead of flat. This allowed the team to be able to push past the previous pressure limit established by other diamond anvils (400 GPa) and get as high as 600 Gpa.

The second involved a new type of infrared spectrometer the research team designed themselves at the Synchrotron SOLEIL facility, which allowed them to measure the sample. Once their hydrogen sample had reached pressures of 425 GPa and temperatures of 80 K (-193 °C; -316 °F), they reported that it began absorbing all the infrared radiation, thereby indicated that they had “closed the band gap“.

In addition, this latest study has yet to be peer-reviewed and their experiment validated by other physicists. However, the French team and their experimental results have some powerful allies. One person is Maddury Somayazulu, an associate research professor at the Argonne National Laboratory who was not involved in this study. As he said in an interview with Gizmodo:

“I think this is really a Nobel-prize worthy discovery. It always was, but this probably represents one of the cleanest and most comprehensive pieces of work on pure hydrogen.” Somayazulu also expressed that he knows the study’s lead author Paul Dumas “very well“, and that Dumas is an “incredibly careful and systematic scientist.”

Another physicist who spoke positively of this latest experiment is Alexander Goncharov, a staff scientist from the Carnegie Institute for Science’s Geophysical Laboratory.

Source: https://www.nature.com/
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https://www.sciencealert.com/

Researchers have developed an ultra-thin and ultra-flexible electronic material that could be printed and rolled out like newspaper, for the touchscreens of the future. The touch-responsive technology is 100 times thinner than existing touchscreen materials and so pliable it can be rolled up like a tube.

To create the new conductive sheet, an RMIT University-led team used a thin film common in mobile phone touchscreens and shrunk it from 3D to 2D, using liquid metal chemistry. The nano-thin sheets are readily compatible with existing electronic technologies and because of their incredible flexibility, could potentially be manufactured through roll-to-roll (R2R) processing just like a newspaper. Lead researcher Dr Torben Daeneke said most mobile phone touchscreens were made of a transparent material, indium-tin oxide, that was very conductive but also very brittle.

“We’ve taken an old material and transformed it from the inside to create a new version that’s supremely thin and flexible,” said Daeneke, an Australian Research Council DECRA Fellow at RMIT. “You can bend it, you can twist it, and you could make it far more cheaply and efficiently than the slow and expensive way that we currently manufacture touchscreens. “Turning it two-dimensional also makes it more transparent, so it lets through more light. “This means a mobile phone with a touchscreen made of our material would use less power, extending the battery life by roughly 10%.”

The research, with collaborators from UNSW, Monash University and the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), is published in the journal Nature Electronics.

Source: https://www.rmit.edu.au/

Hologram techniques are already used in our everyday life. A hologram sticker to prevent from counterfeiting money, Augmented Reality navigation projected in front mirror of a car to guide directions, and Virtual Reality game that allows a user to play in a virtual world with a feeling of live are just a few examples to mention. Recently, thinner and lighter meta-hologram operating in forward and backward directions has been developed. As seen in the movie, Black Panther, people from Wakanda Kingdom communicate to each other through the hologram and, this specific movie scene seems to become reality soon that we can exchange different information with people from different locations.

Junsuk Rho, professor of POSTECH Mechanical Engineering and Chemical Engineering Department in Korea, with his student, Inki Kim developed a multifunctional meta-hologram from a monolayer meta-holographic optical device that can create different hologram images depending on a direction of light incident on the device. Their research accomplishment has been introduced as a cover story in the January 2020 issue of Nanoscale Horizons.

Televisions and beam projectors can only transmit intensity of lights but holographic techniques can save light intensity and its phase information to play movies in three-dimensional spaces. At this time, if metamaterials are used, a user can change nano structures, size, and shapes as desired and can control light intensity and phase at the same time. Meta-hologram has pixel sizes as small as 300 to 400 nanometers but can display very high resolution of holographic images with larger field of view compared to existing hologram projector such as spatial light modulator.

However, the conventional meta-holograms can display images when incident light is in one direction and cannot when light is in the other direction.

To solve such a problem, the research team used two different types of metasurfaces.^* One metasurface was designed to have phase information when incident light was in the forward direction and the other one to operate when light was in backward direction. As a result, they confirmed that these could display different images in real-time depending on the directions of light.

In addition, the team applied dual magnetic resonances^*2 and antiferromagnetic resonances^*3, which are phenomena occurring in silicon nanopillars, to nanostructure design to overcome low efficiency of the conventional meta-hologram. This newly made meta-hologram demonstrated diffraction efficiency higher than 60% (over 70% in simulation) and high-quality and clear images were observed. Furthermore, the new meta-hologram uses silicon and it can be easily produced by following through the conventional semiconductor manufacturing process. The meta-hologram operating in both directions, forward and backward, is expected to set a new hologram platform that can transmit various information to multiple users from different locations, overcoming the limits of the conventional ones which could only transmit one image to a limited location.

“Microscopic, ultrathin, ultralightweight flat optical devices based on a metasurface is an impressive technique with great potentials as it can not only perform the functions of the conventional optical devices but also demonstrate multiple functions depending on how its metasurface is designed. Especially, we developed a meta-hologram optical device that operated in forward and backward directions and it could transmit various visual information to multiple users from different locations simultaneously. We anticipate that this new development can be employed in multiple applications such as holograms for performances, entertainment, exhibitions,  automobiles and more,”, said Junsuk Rho who is leading research on metamaterials.

Source: http://postech.ac.kr/

A drug-coated nanoparticle reduces plaque buildup in mouse arteries without causing harmful side effects, researchers have found.

Atherosclerosis, the accumulation of plaque inside artery walls, can lead to heart attacks and strokes. It’s the world’s No. 1 killer. Available therapies treat risk factors such as high blood pressure and high cholesterol but fail to address the accumulation of diseased cells and inflammation within artery walls.

“This is precision medicine,” said Nicholas Leeper, MD, professor of vascular surgery and cardiovascular medicine. “We used the nanotubes to deliver a payload like a Trojan horse.”

Leeper, who sees patients at Stanford Health Care’s vascular and endovascular care clinic, is a senior author of a paper about the research that was published Jan. 27 in Nature Nanotechnology. The other senior author is Bryan Smith, PhD, a former visiting associate professor at the School of Medicine. He is now an associate professor of biomedical engineering at Michigan State University.

Source: http://med.stanford.edu/

The world is in the midst of a global “superbug” crisis. Antibiotic resistance has been found in numerous common bacterial infections, including tuberculosis, gonorrhoea and salmonellosis, making them difficult – if not impossible – to treat. We’re on the cusp of a “post-antibiotic era”, where there are fewer treatment options for such antibiotic-resistant strains. Given estimates that antibiotic resistance will cause 10 million deaths a year by 2050, finding new methods for treating harmful infections is essential.

Strange as it might sound, viruses might be one possible alternative to antibiotics for treating bacterial infections. Bacteriophages (also known as phages) are viruses that infect bacteria.

They’re estimated to be the most abundant organisms on Earth, with probably more than 10³¹ bacteriophages on the planet. They can survive in many environments, including deep sea trenches and the human gut. While phages are efficient killers of bacteria, they don’t infect human cells and are harmless to humans.

Although phage therapy was used in the 1930s, it has since become a forgotten cure in the west. Although the treatment became commonplace in the former Soviet Union, it wasn’t adopted by western countries largely because of the discovery of antibiotics, which became widespread after World War II.

Bacteriophages are effective against bacteria because they’re able to attach themselves to the cell if they recognise specific molecules called receptors. This is the first step in the “infection” process. After attaching to the bacterial cell, the phage then injects its DNA inside the bacteria.

This causes one of two things to happen. After being injected with the phage’s DNA, the virus will take over the bacterial cell’s replication mechanism and start producing more phages. This process is known as a “lytic infection”. This disintegrates the cell, allowing the newly produced viruses to leave the host cell to infect other bacterial cells.

But sometimes, the phage DNA gets incorporated into the bacterial host’s chromosome instead, becoming a “prophage”. It usually remains dormant but environmental factors, such as UV radiation or the presence of certain chemicals such as those found in sunscreen, can cause the phage to “wake up”, start a lytic infection, take over the host cell and destroy it.

Lytic bacteriophages are preferred for treatment because they don’t integrate into the bacterial host’s chromosome. But it’s not always possible to develop lytic bacteriophages that can be used against all types of bacteria. As each type of phage is only able to infect specific types of bacteria, they can’t infect a bacterial cell unless the bacteriophage can find specific receptors on the bacterial cell surface.

However, engineering techniques can remove the bacteriophage’s ability to integrate into the host’s genome, making them useful for treatment. Engineered phages have even successfully treated a drug-resistant Mycobacterium abscessus infection in a 15-year-old girl.

Source: https://www.realclearscience.com/

A new driverless bullet train connecting the Chinese cities of Beijing and Zhangjiakou is capable of reaching a top speed of up to 217mph (350km/h), making it the world’s fastest autonomous train in operation.

The new service, launched in the build-up to the Beijing 2022 Winter Olympic and Paralympic games, will reduce travel time between the capital and Zhangjiakou, which will stage most of the skiing events, from three hours to less than one. Some trains will complete the 108-mile route in 45 minutes. The original Beijing-Zhangjiakou line opened in 1909, when the same journey took around eight hours. The trains will start and stop at stations automatically to a precise timetable, and change speed depending on limits between stations. However, a monitoring attendant will still be on board in case of emergencies.

The line, also known as the Jingzhang intercity railway, took four years to complete and has 10 stations, including Badaling Changcheng, for access to the Great Wall of China. The first train began operating on 30 December, running from Beijing to Taizicheng, which will also hold some Olympic skiing events and is the closet station to the Olympic village.

Cabins on the “smart” autonomous trains have large storage areas for winter sports equipment, seats with 5G touchscreen control panels, intelligent lighting, thousands of real-time safety sensors and removable seats for passengers in wheelchairs. Facial-recognition technology and robots will be used in stations to assist with directions, luggage and paperless check-in.

Source: https://www.theguardian.com/

According to ancient lore, Genghis Khan instructed his horsemen to wear silk vests underneath their armor to better protect themselves against an onslaught of arrows during battle. Since the time of Khan, body armor has significantly evolved — silk has given way to ultra-hard materials that act like impenetrable walls against most ammunition. However, even this armor can fail, particularly if it is hit by high-speed ammunition or other fast-moving objects.

Researchers at Texas A&M University have formulated a new recipe that can prevent weaknesses in modern-day armor. By adding a tiny amount of the element silicon to boron carbide, a material commonly used for making body armor, they discovered that bullet-resistant gear could be made substantially more resilient to high-speed impacts.

“For the past 12 years, researchers have been looking for ways to reduce the damage caused by the impact of high-speed bullets on armor made with boron carbide,” said Kelvin Xie, assistant professor in the Department of Materials Science and Engineering. “Our work finally addresses this unmet need and is a step forward in designing superior body armor that will safeguard against even more powerful firearms during combat.”

Boron carbide, dubbed “black diamond,” is a man-made material, which ranks second below another synthetic material called cubic boron nitride for hardness. Unlike cubic boron nitride, however, boron carbide is easier to produce on a large scale. Also, boron carbide is harder and lighter than other armor materials like silicon carbide, making it an ideal choice for protective gear, particularly ballistic vests.

Despite boron carbide’s many desirable qualities, its main shortfall is that it can damage very quickly upon high-velocity impact.

“Boron carbide is really good at stopping bullets traveling below 900 meters per second, and so it can block bullets from most handguns quite effectively,” Xie said. “But above this critical speed, boron carbide suddenly loses its ballistic performance and is not as effective.”

Scientists know high-speed jolts cause boron carbide to have phase transformations — a phenomenon where a material changes its internal structure such that it is in two or more physical states, like liquid and solid, at the same time. The bullet’s impact thus converts boron carbide from a crystalline state where atoms are systematically ordered to a glass-like state where atoms are haphazardly arranged. This glass-like state weakens the material’s integrity at the site of contact between the bullet and boron carbide.

“When boron carbide undergoes phase transformation, the glassy phase creates a highway for cracks to propagate,” Xie said. “So, any local damage caused by the impact of a bullet easily travels throughout the material and causes progressively more damage.”

Previous work using computer simulations predicted that adding a small quantity of another element, such as silicon, had the potential to make boron carbide less brittle. Xie and his group investigated if adding a tiny quantity of silicon also reduced phase transformation.

Xie and his collaborators found that even with tiny quantities of silicon, the extent of phase transformation went down by 30%, noticeably reducing the damage from the indentation.

Source: https://today.tamu.edu/

Harvesting sunlight, researchers of the Center for Integrated Nanostructure Physics, within the Institute for Basic Science (IBS, South Korea) published in Materials Today a new strategy to transform carbon dioxide (CO₂) into oxygen (O₂) and pure carbon monoxide (CO) without side-products in water. This artificial photosynthesis method could bring new solutions to environmental pollution and global warming.

While, in green plants, photosynthesis fixes CO₂ into sugars, the artificial photosynthesis reported in this study can convert CO₂ into oxygen and pure CO as output. The latter can then be employed for a broad range of applications in electronics, semiconductor, pharmaceutical, and chemical industries. The key is to find the right high-performance photocatalyst to help the photosynthesis take place by absorbing light, convert CO₂, and ensuring an efficient flow of electrons, which is essential for the entire system.

Titanium oxide (TiO₂) is a well-known photocatalyst. It has already attracted significant attention in the fields of solar energy conversion and environmental protection due to its high reactivity, low toxicity, chemical stability, and low cost. While conventional TiO₂ can absorb only UV light, the IBS research team reported previously two different types of blue-colored TiO₂ (or “blue titania”) nanoparticles that could absorb visible light.

For the efficient artificial photosynthesis for the conversion of CO₂ into oxygen and pure CO, IBS researchers aimed to improve the performance of these nanoparticles. The resulted  hybrid nanoparticles showed about 200 times higher performance than nanoparticles made of TiO₂ alone and TiO₂/WO₃ without silver.

Source: https://www.ibs.re.kr/

In a backyard in Zimbabwe’s capital, a 50-year-old mother of two is using hydroponics to grow vegetables for some of Harare’s top restaurants, defying drought and an economic crisis that have left millions needing food aid.

Venensia Mukarati, whose day job is an accountant, always had a passion for farming, but no land on which to plant. Just over two years ago she did a web search on how to grow vegetables on the deck of her Harare house, importing a small hydroponics system from Cape Town for $900 that enables plants to draw soluble nutrients from water.

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“The good thing about hydroponics is that it saves water by 90%,” Mukarati said in a 46 square-meter greenhouse where water flowed in a maze of pipes decked with plants. “I buy water because I don’t have a borehole so I cannot do conventional farming,” she told Reuters.

Her immediate desire was for fresh vegetables for the family as the country’s economic fortunes deteriorated and grocery store prices spiraled. But she quickly realized her pastime could be a profitable venture. It now makes $1,100 a month – in a country where some government workers get just $76. In hydroponic farming water is conserved because it is reused multiple times. Hydroponically grown plants also require no pesticides because there are no soil-borne diseases.

Much of southern Africa is in its worst drought in more than a century, with crops failing and some 45 million people in need of food aid. The region’s temperatures are rising at twice the global average, says the International Panel on Climate Change, spurring the need for innovative ideas to get food on tables.

Source: https://www.reuters.com/

Researchers at Mount Sinai have developed last year a novel approach to cancer immunotherapy, injecting immune stimulants directly into a tumor to teach the immune system to destroy it and other tumor cells throughout the body.
The “in situ vaccination” worked so well in patients with advanced-stage lymphoma that it is also undergoing trials in breast and head and neck cancer patients, according to a study published in Nature Medicine in April.
The treatment consists of administering a series of immune stimulants directly into one tumor site. The first stimulant recruits important immune cells called dendritic cells that act like generals of the immune army. The second stimulant activates the dendritic cells, which then instruct T cells, the immune system’s soldiers, to kill cancer cells and spare non-cancer cells. This immune army learns to recognize features of the tumor cells so it can seek them out and destroy them throughout the body, essentially turning the tumor into a cancer vaccine factory.

“The in situ vaccine approach has broad implications for multiple types of cancer,” said lead author Joshua Brody, MD, Director of the Lymphoma Immunotherapy Program at The Tisch Cancer Institute at the Icahn School of Medicine at Mount Sinai. “This method could also increase the success of other immunotherapies such as checkpoint blockade.”

After testing the lymphoma vaccine in the lab, it was tested in 11 patients in a clinical trial. Some patients had full remission from months to years. In lab tests in mice, the vaccine drastically increased the success of checkpoint blockade immunotherapy, the type of immunotherapy responsible for the complete remission of former President Jimmy Carter’s cancer and the focus of the 2018 Nobel Prize in Medicine.

Source: https://www.mountsinai.org/