Computers Math

A cross-disciplinary UIUC team has demonstrated a major breakthrough in using automated synthesis to discover new molecules for organic electronics applications.
The technology that enabled the discovery relies on an automated platform for rapid molecular synthesis at scale — which is a game-changer in the field of organic electronics and beyond. Using automated synthesis, the team was able to rapidly scan through a library of molecules with precisely defined structures, thereby uncovering, via single-molecule characterization experiments, a new mechanism for high conductance. The work was just reported in Nature Communications and is the first major result to emerge from the Molecule Maker Lab, which is located in the Beckman Institute for Advanced Science and Technology at the University of Illinois Urbana-Champaign.
The unexpectedly high conductance was uncovered in experiments led by Charles M. Schroeder, who is the James Economy Professor in materials science & engineering and a professor in chemical & biomolecular engineering. The project’s goal was to seek out new molecules with strong conductivity that might be suitable for use in molecular electronics or organic electronics applications. The team’s approach was to systematically append many different side chains to molecular backbones to understand how the side chains affected conductance.
The first stage of the project consisted of synthesizing a large library of molecules to be characterized using single-molecule electronics experiments. If the synthesis had been done with conventional methods, it would have been a long, cumbersome process. That effort was avoided through use of the Molecule Maker Lab’s automated synthesis platform, which was designed to facilitate molecular discovery research that requires testing of large numbers of candidate molecules.
Edward R. Jira, a Ph.D. student in chemical & biomolecular engineering who had a leading role in the project, explained the synthesis platform’s concept. “What’s really powerful… is that it leverages a building-block-based strategy where all of the chemical functionality that we’re interested in is pre-encoded in building blocks that are bench-stable, and you can have a large library of them sitting on a shelf,” he said. A single type of reaction is used repeatedly to couple the building blocks together as needed, and “because we have this diverse building block library that encodes a lot of different functionality, we can access a huge array of different structures for different applications.”
As Schroeder put it, “Imagine snapping Legos together.”
Co-author Martin D. Burke extended the Lego-brick analogy to explain why the synthesizer was so valuable to the experiments — and it wasn’t only because of the rapid production of the initial molecular library. “Because of the Lego-like approach for making these molecules, the team was able to understand why they are super-fast,” he explained. Once the surprisingly fast state was discovered, “using the ‘Legos,’ we could take the molecules apart piece by piece, and swap in different ‘Lego’ bricks — and thereby systematically understand the structure/function relationships that led to this ultrafast conductivity.” More

A University of Minnesota Twin Cities research team has developed a new microfluidic chip for diagnosing diseases that uses a minimal number of components and can be powered wirelessly by a smartphone. The innovation opens the door for faster and more affordable at-home medical testing.
The researchers’ paper is published in Nature Communications, a peer-reviewed, open access, scientific journal published by Nature Research. Researchers are also working to commercialize the technology.
Microfluidics involves the study and manipulation of liquids at a very small scale. One of the most popular applications in the field is developing “lab-on-a-chip” technology, or the ability to create devices that can diagnose diseases from a very small biological sample, blood or urine, for example.
Scientists already have portable devices for diagnosing some conditions — rapid COVID-19 antigen tests, for one. However, a big roadblock to engineering more sophisticated diagnostic chips that could, for example, identify the specific strain of COVID-19 or measure biomarkers like glucose or cholesterol, is the fact that they need so many moving parts.
Chips like these would require materials to seal the liquid inside, pumps and tubing to manipulate the liquid, and wires to activate those pumps — all materials that are difficult to scale down to the micro level. Researchers at the University of Minnesota Twin Cities were able to create a microfluidic device that functions without all of those bulky components.
“Researchers have been extremely successful when it comes to electronic device scaling, but the ability to handle liquid samples has not kept up,” said Sang-Hyun Oh, a professor in the University of Minnesota Twin Cities Department of Electrical and Computer Engineering and senior author of the study. “It’s not an exaggeration that a state-of-the-art, microfluidic lab-on-a-chip system is very labor intensive to put together. Our thought was, can we just get rid of the cover material, wires, and pumps altogether and make it simple?”
Many lab-on-a-chip technologies work by moving liquid droplets across a microchip to detect the virus pathogens or bacteria inside the sample. The University of Minnesota researchers’ solution was inspired by a peculiar real-world phenomenon with which wine drinkers will be familiar — the “legs,” or long droplets that form inside a wine bottle due to surface tension caused by the evaporation of alcohol. More

When designing a next-generation quantum computer, a surprisingly large problem is bridging the communication gap between the classical and quantum worlds. Such computers need a specialized control and readout electronics to translate back and forth between the human operator and the quantum computer’s languages — but existing systems are cumbersome and expensive.
However, a new system of control and readout electronics, known as Quantum Instrumentation Control Kit, or QICK, developed by engineers at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, has proved to drastically improve quantum computer performance while cutting the cost of control equipment.
“The development of the Quantum Instrumentation Control Kit is an excellent example of U.S. investment in joint quantum technology research with partnerships between industry, academia and government to accelerate pre-competitive quantum research and development technologies,” said Harriet Kung, DOE deputy director for science programs for the Office of Science and acting associate director of science for high-energy physics.
The faster and more cost-efficient controls were developed by a team of Fermilab engineers led by senior principal engineer Gustavo Cancelo in collaboration with the University of Chicago whose goal was to create and test a field-programmable gate array-based (FPGA) controller for quantum computing experiments. David Schuster, a physicist at the University of Chicago, led the university’s lab that helped with the specifications and verification on real hardware.
“This is exactly the type of project that combines the strengths of a national laboratory and a university,” said Schuster. “There is a clear need for an open-source control hardware ecosystem, and it is being rapidly adopted by the quantum community.”
Engineers designing quantum computers deal with the challenge of bridging the two seemingly incompatible worlds of quantum and classical computers. Quantum computers are based on the counterintuitive, probabilistic rules of quantum mechanics that govern the microscopic world, which enables them to perform calculations that ordinary computers cannot. Because people live in the macroscopic visible world where classical physics reigns, control and readout electronics act as the interpreter connecting these two worlds. More

Building a plane while flying it isn’t typically a goal for most, but for a team of Harvard-led physicists that general idea might be a key to finally building large-scale quantum computers.
Described in a new paper in Nature, the research team, which includes collaborators from QuEra Computing, MIT, and the University of Innsbruck, developed a new approach for processing quantum information that allows them to dynamically change the layout of atoms in their system by moving and connecting them with each other in the midst of computation.
This ability to shuffle the qubits (the fundamental building blocks of quantum computers and the source of their massive processing power) during the computation process while preserving their quantum state dramatically expands processing capabilities and allows for the self-correction of errors. Clearing this hurdle marks a major step toward building large-scale machines that leverage the bizarre characteristics of quantum mechanics and promise to bring about real-world breakthroughs in material science, communication technologies, finance, and many other fields.
“The reason why building large scale quantum computers is hard is because eventually you have errors,” said Mikhail Lukin, the George Vasmer Leverett Professor of Physics, co-director of the Harvard Quantum Initiative, and one of the senior authors of the study. “One way to reduce these errors is to just make your qubits better and better, but another more systematic and ultimately practical way is to do something which is called quantum error correction. That means that even if you have some errors, you can correct these errors during your computation process with redundancy.”
In classical computing, error correction is done by simply copying information from a single binary digit or bit so it’s clear when and where it failed. For example, one single bit of 0 can be copied three times to read 000. Suddenly, when it reads 001, it’s clear where the error is and can be corrected. A foundational limitation of quantum mechanics is that information can’t be copied, making error correction difficult.
The workaround the researchers implement creates a sort of backup system for the atoms and their information called a quantum error correction code. The researchers use their new technique to create many of these correction codes, including what’s known as a toric code, and it spreads them out throughout the system. More

Researchers at the University of California San Diego have developed a smartphone app that could allow people to screen for Alzheimer’s disease, ADHD and other neurological diseases and disorders — by recording closeups of their eye.
The app uses a near-infrared camera, which is built into newer smartphones for facial recognition, along with a regular selfie camera to track how a person’s pupil changes in size. These pupil measurements could be used to assess a person’s cognitive condition.
The technology is described in a paper that will be presented at the ACM Computer Human Interaction Conference on Human Factors in Computing Systems (CHI 2022), which will take place from April 30 to May 5 in New Orleans as a hybrid-onsite event.
“While there is still a lot of work to be done, I am excited about the potential for using this technology to bring neurological screening out of clinical lab settings and into homes,” said Colin Barry, an electrical and computer engineering Ph.D. student at UC San Diego and the first author of the paper, which received an Honorable Mention for Best Paper award. “We hope that this opens the door to novel explorations of using smartphones to detect and monitor potential health problems earlier on.”
Pupil size can provide information about a person’s neurological functions, recent research has shown. For example, pupil size increases when a person performs a difficult cognitive task or hears an unexpected sound.
Measuring the changes in pupil diameter is done by performing what’s called a pupil response test. The test could offer a simple and easy way to diagnose and monitor various neurological diseases and disorders. However, it currently requires specialized and costly equipment, making it impractical to perform outside the lab or clinic. More

In a proof-of-concept study, researchers have created self-assembled, protein-based circuits that can perform simple logic functions. The work demonstrates that it is possible to create stable digital circuits that take advantage of an electron’s properties at quantum scales.
One of the stumbling blocks in creating molecular circuits is that as the circuit size decreases the circuits become unreliable. This is because the electrons needed to create current behave like waves, not particles, at the quantum scale. For example, on a circuit with two wires that are one nanometer apart, the electron can “tunnel” between the two wires and effectively be in both places simultaneously, making it difficult to control the direction of the current. Molecular circuits can mitigate these problems, but single-molecule junctions are short-lived or low-yielding due to challenges associated with fabricating electrodes at that scale.
“Our goal was to try and create a molecular circuit that uses tunneling to our advantage, rather than fighting against it,” says Ryan Chiechi, associate professor of chemistry at North Carolina State University and co-corresponding author of a paper describing the work.
Chiechi and co-corresponding author Xinkai Qiu of the University of Cambridge built the circuits by first placing two different types of fullerene cages on patterned gold substrates. They then submerged the structure into a solution of photosystem one (PSI), a commonly used chlorophyll protein complex.
The different fullerenes induced PSI proteins to self-assemble on the surface in specific orientations, creating diodes and resistors once top-contacts of the gallium-indium liquid metal eutectic, EGaIn, are printed on top. This process both addresses the drawbacks of single-molecule junctions and preserves molecular-electronic function.
“Where we wanted resistors we patterned one type of fullerene on the electrodes upon which PSI self-assembles, and where we wanted diodes we patterned another type,” Chiechi says. “Oriented PSI rectifies current — meaning it only allows electrons to flow in one direction. By controlling the net orientation in ensembles of PSI, we can dictate how charge flows through them.”
The researchers coupled the self-assembled protein ensembles with human-made electrodes and made simple logic circuits that used electron tunneling behavior to modulate the current.
“These proteins scatter the electron wave function, mediating tunneling in ways that are still not completely understood,” Chiechi says. “The result is that despite being 10 nanometers thick, this circuit functions at the quantum level, operating in a tunneling regime. And because we are using a group of molecules, rather than single molecules, the structure is stable. We can actually print electrodes on top of these circuits and build devices.”
The researchers created simple diode-based AND/OR logic gates from these circuits and incorporated them into pulse modulators, which can encode information by switching one input signal on or off depending on the voltage of another input. The PSI-based logic circuits were able to switch a 3.3 kHz input signal — which, while not comparable in speed to modern logic circuits, is still one of the fastest molecular logic circuits yet reported.
“This is a proof-of-concept rudimentary logic circuit that relies on both diodes and resistors,” Chiechi says. “We’ve shown here that you can build robust, integrated circuits that work at high frequencies with proteins.
“In terms of immediate utility, these protein-based circuits could lead to the development of electronic devices that enhance, supplant and/or extend the functionality of classical semiconductors.”
The research appears in Nature Communications. Co-authors Chiechi and Qiu were formerly at University of Groningen, the Netherlands.
Story Source:
Materials provided by North Carolina State University. Original written by Tracey Peake. Note: Content may be edited for style and length. More

The December 2014 North American Storm Complex was a powerful winter storm, referred to by some as California’s “Storm of the Decade.” Fueled by an atmospheric river originating over the tropical waters of the Pacific Ocean, the storm dropped 8 inches of rainfall in 24 hours, sported wind gusts of 139 miles per hour, and left 150,000 households without power across the San Francisco Bay Area.
Writing in Weather and Climate Extremes this week, researchers described the potential impacts of climate change on extreme storms in the San Francisco Bay area, among them the December 2014 North American Storm Complex.
Re-simulating five of the most powerful storms that have hit the area, they determined that under future conditions some of these extreme events would deliver 26-37% more rain, even more than is predicted simply by accounting for air’s ability to carry more water in warmer conditions.
However, they found these increases would not occur with every storm, only those that include an atmospheric river accompanied by an extratropical cyclone.
The research — funded by the City and County of San Francisco and in partnership with agencies including the San Francisco Public Utilities Commission, Port of San Francisco, and San Francisco International Airport — will help the region plan its future infrastructure with mitigation and sustainability in mind.
“Having this level of detail is a game changer,” said Dennis Herrera, General Manager of the San Francisco Public Utilities Commission, which was the lead City agency on the study. “This groundbreaking data will help us develop tools to allow our port, airport, utilities, and the City as a whole to adapt to our changing climate and increasingly extreme storms.”
These first-of-their-kind forecasts for the city were made possible by the Stampede2 supercomputer at the Texas Advanced Computing Center (TACC) and the Cori system at the National Energy Research Scientific Computing Center (NERSC) — two of the most powerful supercomputers in the world, supported by the National Science Foundation and Department of Energy respectively. More

In the quest to build smart skin that mimics the sensing capabilities of natural skin, ionic skins have shown significant advantages. They’re made of flexible, biocompatible hydrogels that use ions to carry an electrical charge. In contrast to smart skins made of plastics and metals, the hydrogels have the softness of natural skin. This offers a more natural feel to the prosthetic arm or robot hand they are mounted on, and makes them comfortable to wear.
These hydrogels can generate voltages when touched, but scientists did not clearly understand how — until a team of researchers at UBC devised a unique experiment, published today in Science.
“How hydrogel sensors work is they produce voltages and currents in reaction to stimuli, such as pressure or touch — what we are calling a piezoionic effect. But we didn’t know exactly how these voltages are produced,” said the study’s lead author Yuta Dobashi, who started the work as part of his master’s in biomedical engineering at UBC.
Working under the supervision of UBC researcher Dr. John Madden, Dobashi devised hydrogel sensors containing salts with positive and negative ions of different sizes. He and collaborators in UBC’s physics and chemistry departments applied magnetic fields to track precisely how the ions moved when pressure was applied to the sensor.
“When pressure is applied to the gel, that pressure spreads out the ions in the liquid at different speeds, creating an electrical signal. Positive ions, which tend to be smaller, move faster than larger, negative ions. This results in an uneven ion distribution which creates an electric field, which is what makes a piezoionic sensor work.”
The researchers say this new knowledge confirms that hydrogels work in a similar way to how humans detect pressure, which is also through moving ions in response to pressure, inspiring potential new applications for ionic skins. More