University of Tokyo performs molecular dynamics simulations to show physical origin of glass formation from multi-component systems

Japanese researchers from the Institute of Industrial Science at The University of Tokyo used molecular dynamics calculations to simulate the glass-forming ability of metallic mixtures. They show that even small changes in composition can strongly influence the likelihood that material will assume a crystalline versus a glassy state upon cooling. This work may lead to a universal theory of glass formation and cheaper, more resilient, electroconductive glass.

If you have important guests coming over for dinner, you might set your table with expensive "crystal" glasses. To scientists, however, crystal and glass are actually two very different states that a liquid might assume when cooled. A crystal has a defined three-dimensional lattice structure that repeats indefinitely, while the glass is an amorphous solid that lacks long-range ordering. Current theories of glass formation cannot accurately predict which metallic mixtures will "vitrify" to form a glass and which will crystallize. A better, more comprehensive understanding of glass formation would be a great help when designing new recipes for mechanically tough, electrically conductive materials.

Now, researchers at the University of Tokyo have used supercomputer simulations of three prototypical metallic systems to study the process of glass formation. "We found that the ability for a multi-component system to form a crystal, as opposed to a glass, can be disrupted by slight modifications to the composition," first author Yuan-Chao Hu says. Scientists at The University of Tokyo use supercomputer simulations to model the effects of elemental composition on the glass-forming ability of metallic mixtures, which may lead to tough, electroconductive glasses{module INSIDE STORY}

Stated simply, glass formation is the consequence of a material avoiding crystallization when cooled. This locks the atoms into a "frozen" state before they can organize themselves into their energy-minimizing pattern. The simulations showed that a critical factor determining the rate of crystallization was the liquid-crystal interface energy.

The researchers also found that changes in elemental composition can lead to local atomic orderings that frustrate the process of crystallization with arrangements incompatible with the crystal's usual form. Specifically, these structures can prevent tiny crystals from acting as "seeds" that nucleate the growth of ordered regions in the sample. In contrast with previous explanations, the scientists determined that the chemical potential difference between the liquid and crystal phases has only a small effect on glass formation.

"This work represents a significant advancement in our understanding of the fundamental physical mechanism of vitrification," senior author Hajime Tanaka says. "The results of this project may also help glass manufacturers design new multi-component systems that have certain desired properties, such as resilience, toughness, and electroconductivity."

SwRI researchers evaluate impact of wastewater systems on Edwards Aquifer

The study supports the City of San Antonio's aquifer protection efforts

Southwest Research Institute developed an integrated hydrologic supercomputer model to evaluate the impact of different types of wastewater disposal facilities on the Edwards Aquifer, the primary water source for San Antonio and its surrounding communities. The research results will guide authorities on what actions to take to protect the quality and quantity of water entering the aquifer.

The two-year study, which concluded in July, was funded through the City of San Antonio's Edwards Aquifer Protection Plan (EAPP) under the direction of the San Antonio River Authority. The tax-funded EAPP identifies and protects land and water crucial to the well-being of the aquifer. SwRI researchers selected the nearly 25-square-mile Helotes Creek Watershed in northwest Bexar County as the study area. They combined surface and groundwater data, including streamflow and groundwater elevations, along with climate, soil, and topographic input to create an integrated model of the watershed. SwRI researchers selected the Helotes Creek Watershed in northwest Bexar County to study how different wastewater treatment scenarios could affect the Edwards Aquifer.{module INSIDE STORY}

"We chose the Helotes Creek Watershed because it is entirely in the contributing and recharge zones of the Edwards Aquifer. Rainfall and bodies of water over these key zones replenish the aquifer," said SwRI's Mauricio Flores, who helped lead the project. "Our findings are intended to provide insight on which wastewater practices offer the best protection for the aquifer when considering new development in these critical zones."

SwRI's Water Resources group constructed a base case model, replicating what is happening now with septic systems already located in the watershed area. Starting with that data, they evaluated what would happen if they added wastewater disposal facilities to the region. Scenarios evaluated included additional septic or onsite sewage systems, facilities that reuse wastewater for irrigation, and systems that dispose of wastewater in nearby creeks or rivers.

"We considered a range of hypothetical scenarios. The size and capacity of the hypothesized wastewater facilities were consistent with possible residential development in the Helotes Creek Watershed area," said Dr. Ronald Green, SwRI technical advisor, and project manager. "Our results predicted that installing additional wastewater systems in the region, regardless of type, would increase the amount of wastewater discharged to the environment and significantly degrade the watershed and the quality of water recharging the Edwards Aquifer."

The Helotes Creek Watershed study was the first of its kind in this area. The findings are applicable to most watersheds in the aquifer's contributing and recharge zones. However, SwRI researchers recommend expanding the study to the outside of Bexar County to demonstrate how development and increased wastewater disposal would impact these areas.

"The results of the study not only highlight the impact development could have on the aquifer, but can also be used to prioritize the protection of land, rivers, and streams that recharge the aquifer," said Flores. "Our findings show this type of research is vital to protecting important water resources."

The City of San Antonio is conducting additional EAPP-funded research aimed at protecting the aquifer. An official city report, which will include the SwRI study, is expected in 2023.

UK deploys public health systems to decode COVID-19

Existing public health monitoring systems in the UK could improve understanding of the risk factors associated with severe COVID-19

Research published in the journal Microbial Genomics describes how national surveillance systems can be linked with the UK Biobank. This pooled data could then be used to understand how genetics and other epidemiological factors impact the risk of developing severe infection.

The UK Biobank (UKB) is an international health resource that enables researchers to understand the genetic and lifestyle determinants of common diseases. The researchers linked UKB with Public Health England's Second-Generation Surveillance System (SGSS), a centralized microbiology database used for national disease surveillance in England. SGSS holds data collected in clinical diagnostic laboratories in England, including test results for SARS-CoV-2. 37 covid19 14bb9{module INSIDE STORY}

Large cohorts such as UKB are a useful resource for understanding how a disease behaves in different groups, according to Dr. Danny Wilson, Associate Professor at the Big Data Institute, University of Oxford (UK). He said: "Large datasets are helpful for detecting risk factors, including those that have modest effects or vary from person-to-person, and for providing a sound footing for conclusions by reducing statistical noise. These discoveries help scientists better understand the disease and could inspire efforts aimed at improving treatment."

By linking the two systems, researchers hope to facilitate research into the risk factors for severe COVID-19. Repurposing public health systems in this way can provide near-to-real-time data on SARS-CoV-2, and allow researchers to understand the spread, testing, and disease characteristics of the virus.

This new super computerized system will provide the weekly linkage of test results to UKB and other cohorts. The UK Biobank database consists of around 500,000 men and women in the UK, aged 50+. This group is particularly appropriate for the study of COVID-19, as the severity of the disease increases with age. Further data is also being released by UKB, according to Dr. Wilson: "UK Biobank is releasing, or have released other data relevant to COVID-19, like mortality records, and they plan to release hospital episode statistics and primary care data soon too".

Their data provides an in-depth analysis of disease severity, symptoms, and risk in people from the UKB database. Researchers hope that this data can reveal additional risk factors for severe infection and improve understanding of the disease. "By providing information about COVID-19 to large cohorts including UK Biobank, INTERVAL, COMPARE, Genes & Health, Genomics England and the National Institute for Health Research (NIHR) Biorepository, this work facilitates research into lifestyle, medical and genetic risk factors," said Dr. Wilson.