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Archive for the ‘chemistry’ category: Page 300

Jul 12, 2020

Rock ’n’ Control: Physicists Use Oscillations of Atoms to Control a Phase Transition

Posted by in categories: chemistry, particle physics

The goal of “Femtochemistry” is to film and control chemical reactions with short flashes of light. Using consecutive laser pulses, atomic bonds can be excited precisely and broken as desired. So far, this has been demonstrated for selected molecules. Researchers at the University of Göttingen and the Max Planck Institute for Biophysical Chemistry have now succeeded in transferring this principle to a solid, controlling its crystal structure on the surface. The results have been published in the journal Nature.

The team, led by Jan Gerrit Horstmann and Professor Claus Ropers, evaporated an extremely thin layer of indium onto a silicon crystal and then cooled the crystal down to −220 degrees Celsius. While the indium atoms form conductive metal chains on the surface at room temperature, they spontaneously rearrange themselves into electrically insulating hexagons at such low temperatures. This process is known as the transition between two phases – the metallic and the insulating – and can be switched by laser pulses. In their experiments, the researchers then illuminated the cold surface with two short laser pulses and immediately afterwards observed the arrangement of the indium atoms using an electron beam. They found that the rhythm of the laser pulses has a considerable influence on how efficiently the surface can be switched to the metallic state.

This effect can be explained by oscillations of the atoms on the surface, as first author Jan Gerrit Horstmann explains: “In order to get from one state to the other, the atoms have to move in different directions and in doing so overcome a sort of hill, similar to a roller coaster ride. A single laser pulse is not enough for this, however, and the atoms merely swing back and forth. But like a rocking motion, a second pulse at the right time can give just enough energy to the system to make the transition possible.” In their experiments, the physicists observed several oscillations of the atoms, which influence the conversion in very different ways.

Jul 12, 2020

Self Fuelled Transformable Liquid Metal Machine

Posted by in categories: chemistry, food, robotics/AI

Synthetic self-fuelled motors, which can spontaneously convert chemical energy into mechanical activity to induce autonomous locomotion, are excellent candidates for making self-powered machines, detectors/sensors, and novel robots. The present lab (Zhang et al. in Adv Mater 27:2648–2655, 2004 [1]). discovered an extraordinary self-propulsion mechanism of synthetic motors based on liquid metal objects. Such motors could swim in a circular Petri dish or different structured channels containing aqueous solution with a pretty high velocity on the order of centimeters per second, and surprisingly long lifetime lasting for more than one hour without any assistance of external energy. The soft material liquid metal enables the motors to self-deform, which makes them highly adaptable for accomplishing tough missions in special environment. Interestingly, the motors work just like biomimetic mollusk since they closely resemble the nature by “eating” aluminum as “food”, and can change shape by closely conforming to the geometrical space it voyages in. From practical aspect, one can thus develop a self-powered pump based on the actuation of the liquid metal enabled motor. Further, such pump can also be conceived to work as a cooler. Apart from different geometrical channels, several dominating factors, including the volume of the motor, the amount of aluminum, the property of the solution and the material of the substrate etc., have been disclosed to influence the performance of the autonomous locomotion evidently. This artificial mollusk system suggests an exciting platform for molding the liquid metal science to fundamentally advance the field of self-driven soft machine design, microfluidic systems, and eventually lead to the envisioned dynamically reconfigurable intelligent soft robots in the near future. In this chapter, the typical behaviors and fundamental phenomena of the self fuelled transformable liquid metal machines were illustrated.

Jul 10, 2020

Robot scientist discovers a new catalyst

Posted by in categories: biotech/medical, chemistry, robotics/AI

The robot seen here can work almost 24–7, carrying out experiments by itself. The automated scientist – the first of its kind – can make its own decisions about which chemistry experiments to perform next, and has already discovered a new catalyst.

With humanoid dimensions, and working in a standard laboratory, it uses instruments much like a human does. Unlike a real person, however, this 400 kg robot has infinite patience, and works for 21.5 hours each day, pausing only to recharge its battery.

This new technology – reported in the journal Nature and featured on the front cover – is designed to tackle problems of a scale and complexity that are currently beyond our grasp. New drug formulations could be autonomously discovered, for example, by searching vast and unexplored chemical spaces.

Jul 8, 2020

Physicists use oscillations of atoms to control a phase transition

Posted by in categories: chemistry, particle physics

The goal of ‘femtochemistry’ is to film and control chemical reactions with short flashes of light. Using consecutive laser pulses, atomic bonds can be excited precisely and broken as desired. So far, this has been demonstrated for selected molecules. Researchers at the University of Göttingen and the Max Planck Institute for Biophysical Chemistry have now succeeded in transferring this principle to a solid, controlling its crystal structure on the surface. The results have been published in the journal Nature.

The team, led by Jan Gerrit Horstmann and Professor Claus Ropers, evaporated an extremely thin layer of indium onto a silicon crystal and then cooled the crystal down to −220 degrees Celsius. While the indium form conductive metal chains on the at room temperature, they spontaneously rearrange themselves into electrically insulating hexagons at such low temperatures. This process is known as the transition between two phases—the metallic and the insulating—and can be switched by laser pulses. In their experiments, the researchers then illuminated the cold surface with two short laser pulses and immediately afterwards observed the arrangement of the indium atoms using an electron beam. They found that the rhythm of the has a considerable influence on how efficiently the surface can be switched to the metallic state.

This effect can be explained by oscillations of the atoms on the surface, as first author Jan Gerrit Horstmann explains: “In order to get from one state to the other, the atoms have to move in different directions and in doing so overcome a sort of hill, similar to a roller coaster ride. A single laser pulse is not enough for this, however, and the atoms merely swing back and forth. But like a rocking motion, a second pulse at the right time can give just enough energy to the system to make the transition possible.” In their experiments the physicists observed several oscillations of the atoms, which influence the conversion in very different ways.

Jul 7, 2020

Tiny Weed-Killing Robots Could Make Pesticides Obsolete

Posted by in categories: chemistry, food, robotics/AI, sustainability

Clint Brauer’s farm outside of Cheney, Kansas, could be described as Old MacDonald’s Farm plus robots. Along with 5,500 square feet of vegetable-growing greenhouses, classes teaching local families to grow their food, a herd of 105 sheep, and Warren G—a banana-eating llama named after the rapper—is a fleet of ten, 140-pound, battery-operated robots.

Brauer, the co-founder of Greenfield Robotics, grew up a farm kid. He left for the big city tech and digital world, but eventually made his way back to the family farm. Now, it’s the R&D headquarters for the Greenfield Robotics team, plus a working farm.

When Brauer returned to his agricultural roots, he did so with a purpose: to prove that food could be grown without harmful chemicals and by embracing soil- and planet-friendly practices. He did just that, becoming one of the premier farmers growing vegetables in Kansas without pesticides, selling to local markets, grocery store chains, and chefs.

Jul 6, 2020

Compounds halt SARS-CoV-2 replication

Posted by in categories: biotech/medical, chemistry, health

As the death toll from the COVID-19 pandemic mounts, scientists worldwide continue their push to develop effective treatments and a vaccine for the highly contagious respiratory virus.

University of South Florida Health (USF Health) Morsani College of Medicine scientists recently worked with colleagues at the University of Arizona College of Pharmacy to identify several existing compounds that block replication of the COVID-19 virus (SARS-CoV-2) within grown in the laboratory. The inhibitors all demonstrated potent chemical and structural interactions with a critical to the virus’s ability to proliferate.

The research team’s discovery study appeared June 15 in Cell Research, a high-impact Nature journal.

Jul 6, 2020

Graphene barrier creates mosquito-proof fabric

Posted by in categories: biotech/medical, chemistry

(Credit: Getty Images)

According to the study in PNAS, the ultra-thin yet strong material acts as a barrier that mosquitoes can’t bite through. The graphene also blocks chemical signals mosquitoes use to sense that a blood meal is near, blunting their urge to bite in the first place.

Jul 5, 2020

NASA Is Releasing a Fragrance That Smells Like Space

Posted by in categories: chemistry, space

NASA is bringing the smell of space to Earth with a new fragrance called Eau de Space. The fragrance was developed by chemist Steve Pearce, who was contracted by NASA in 2008 to recreate the scent of space.

With his knowledge of flavor and fragrance chemistry, Pearce used astronauts’ descriptions of the smell of space to come up with combinations to match what was described as “ozone, hot metal, and fried steak,” CNN reports.

“It’s a bitter kind of smell in addition to being smoky and burned, kind of like a smell from a gun, right after you fire the shot,” astronaut Peggy Whitson told CNN. Eau de Space product manager, Matt Richmond, said he has struggled to accurately describe the fragrance’s scent, adding that astronauts have also likened the smell to “a mix of gunpowder, seared steak, raspberries, and rum.”

Jul 5, 2020

Age-related heart disease linked to gut bacteria metabolite

Posted by in categories: biotech/medical, chemistry, food, life extension

New research from the University of Colorado Boulder has offered some of the clearest evidence to date showing how the gut microbiome produces a metabolite that, over time, contributes to age-related declines in cardiovascular health.

High blood levels of trimethylamine-N-Oxide (TMAO), a metabolic byproduct of digestion, have been strongly linked to negative cardiovascular health. When one eats red meat, eggs or other animal proteins, certain types of gut bacteria feed on chemicals in those foods and produce TMA, or trimethylamine, which is then turned into TMAO in the liver.

A number of studies have linked TMAO to heart disease, however, until now it hasn’t been clear exactly how this metabolite causes cardiovascular damage. A robust new study, published in the journal Hypertension, is offering one of the first thorough mechanistic investigations illustrating how TMAO damages the cardiovascular system.

Jul 5, 2020

A biohybrid synapse with neurotransmitter-mediated plasticity

Posted by in categories: biological, chemistry, robotics/AI, sustainability

Brain-inspired computing paradigms have led to substantial advances in the automation of visual and linguistic tasks by emulating the distributed information processing of biological systems. The similarity between artificial neural networks (ANNs) and biological systems has inspired ANN implementation in biomedical interfaces including prosthetics and brain-machine interfaces. While promising, these implementations rely on software to run ANN algorithms. Ultimately, it is desirable to build hardware ANNs that can both directly interface with living tissue and adapt based on biofeedback. The first essential step towards biologically integrated neuromorphic systems is to achieve synaptic conditioning based on biochemical signalling activity. Here, we directly couple an organic neuromorphic device with dopaminergic cells to constitute a biohybrid synapse with neurotransmitter-mediated synaptic plasticity. By mimicking the dopamine recycling machinery of the synaptic cleft, we demonstrate both long-term conditioning and recovery of the synaptic weight, paving the way towards combining artificial neuromorphic systems with biological neural networks.