Atomic structure of a staphylococcal bacteriophage using cryo-electron microscopy

High-resolution knowledge of structure is a key link between viral biology and potential therapeutic use of the virus to quell bacterial infections.

Peer-Reviewed Publication

UNIVERSITY OF ALABAMA AT BIRMINGHAM

 

IMAGE: THE ANDHRA PHAGE view more 

CREDIT: UAB, DOKLAND LAB

BIRMINGHAM, Ala. – Cryo-electron microscopy by University of Alabama at Birmingham researchers has exposed the structure of a bacterial virus with unprecedented detail. This is the first structure of a virus able to infect Staphylococcus epidermidis, and high-resolution knowledge of structure is a key link between viral biology and potential therapeutic use of the virus to quell bacterial infections.

Bacteriophages or “phages” is the terms used for viruses that infect bacteria. The UAB researchers, led by Terje Dokland, Ph.D., in collaboration with Asma Hatoum-Aslan, Ph.D., at the University of Illinois Urbana-Champaign, have described atomic models for all or part of 11 different structural proteins in phage Andhra. The study is published in Science Advances.

Andhra is a member of the picovirus group. Its host range is limited to S. epidermidis. This skin bacterium is mostly benign but also is a leading cause of infections of indwelling medical devices. “Picoviruses are rarely found in phage collections and remain understudied and underused for therapeutic applications,” said Hatoum-Aslan, a phage biologist at the University of Illinois.

With emergence of antibiotic resistance in S. epidermidis and the related pathogen Staphylococcus aureus, researchers have renewed interest in potentially using bacteriophages to treat bacterial infections. Picoviruses always kill the cells they infect, after binding to the bacterial cell wall, enzymatically breaking through that wall, penetrating the cell membrane and injecting viral DNA into the cell. They also have other traits that make them attractive candidates for therapeutic use, including a small genome and an inability to transfer bacterial genes between bacteria.

Knowledge of protein structure in Andhra and understanding of how those structures allow the virus to infect a bacterium will make it possible to produce custom-made phages tailored to a specific purpose, using genetic manipulation.

“The structural basis for host specificity between phages that infect S. aureus and S. epidermidis is still poorly understood,” said Dokland, a professor of microbiology at UAB and director of the UAB Cryo-Electron Microscopy Core. “With the present study, we have gained a better understanding of the structures and functions of the Andhra gene products and the determinants of host specificity, paving the way for a more rational design of custom phages for therapeutic applications. Our findings elucidate critical features for virion assembly, host recognition and penetration.”

Staphylococcal phages typically have a narrow range of bacteria they can infect, depending on the variable polymers of wall teichoic acid on the surface of different bacterial strains. “This narrow host range is a double-edged sword: On one hand, it allows the phages to target only the specific pathogen causing the disease; on the other hand, it means that the phage may need to be tailored to the patient in each specific case,” Dokland said.

The general structure of Andhra is a 20-faced, roundish icosahedral capsid head that contains the viral genome. The capsid is attached to a short tail. The tail is largely responsible for binding to S. epidermidis and enzymatically breaking the cell wall. The viral DNA is injected into the bacterium through the tail. Segments of the tail include the portal from the capsid to the tail, and the stem, appendages, knob and tail tip.

The 11 different proteins that make up each virus particle are found in multiple copies that assemble together. For instance, the capsid is made of 235 copies each of two proteins, and the other nine virion proteins have copy numbers from two to 72. In total, the virion is made up of 645 protein pieces that include two copies of a 12th protein, whose structure was predicted using the protein structure prediction program AlphaFold.

The atomic models described by Dokland, Hatoum-Aslan, and co-first authors N’Toia C. Hawkins, Ph.D., and James L. Kizziah, Ph.D., UAB Department of Microbiology, show the structures for each protein — as described in molecular language like alpha-helix, beta-helix, beta-strand, beta-barrel or beta-prism. The researchers have described how each protein binds to other copies of that same protein type, such as to make up the hexameric and pentameric faces of the capsid, as well as how each protein interacts with adjacent different protein types.

Electron microscopes use a beam of accelerated electrons to illuminate an object, providing much higher resolution than a light microscope. Cryo-electron microscopy adds the element of super-cold temperatures, making it particularly useful for near-atomic structure resolution of larger proteins, membrane proteins or lipid-containing samples like membrane-bound receptors, and complexes of several biomolecules together.

In the past eight years, new electron detectors have created a tremendous jump in resolution for cryo-electron microscopy over normal electron microscopy. Key elements of this so-called “resolution revolution” for cryo-electron microscopy are:

• Flash-freezing aqueous samples in liquid ethane cooled to below -256 degrees F. Instead of ice crystals that disrupt samples and scatter the electron beam, the water freezes to a window-like “vitreous ice.”
• The sample is kept at super-cold temperatures in the microscope, and a low dose of electrons is used to avoid damage to the proteins.
• Extremely fast direct electron detectors are able to count individual atoms at hundreds of frames per second, allowing sample movement to be corrected on the fly.
• Advanced computing merges thousands of images to generate three-dimensional structures at high resolution. Graphics processing units are used to churn through terabytes of data.
• The microscope stage that holds the sample can also be tilted as images are taken, allowing construction of a three-dimensional tomographic image, similar to a CT scan at the hospital.

The analysis of Andhra virion structure by the UAB researchers started with 230,714 particle images. Molecular reconstruction of the capsid, tail, distal tail and tail tip started with 186,542, 159,489, 159,489 and 159,489 images, respectively. Resolution ranged from 3.50 to 4.90 angstroms.

Support for the study, “Structure and host specificity of Staphylococcus epidermidis bacteriophage Andhra,” came from National Institutes of Health phage therapy grant R21 AI156636.

The UAB Department of Microbiology is part of the Marnix E. Heersink School of Medicine.

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JOURNAL

Science Advances

DOI

10.1126/sciadv.ade0459 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Structure and host specificity of Staphylococcus epidermidis bacteriophage Andhra

Pitch-perfect: Study of World Cup’s turfgrass may help crops yield more from less

Experiments show grass’s resilience-building tricks work for corn, too

Peer-Reviewed Publication

UNIVERSITY OF NEBRASKA-LINCOLN

Grass is famously resilient. But Paspalum vaginatum, a species better known as seashore paspalum, can tolerate stresses diverse and deadly enough to rival camels and cactuses.

Salinity? It’s still worth its salt. Drought? Not thirsty. Heat? No sweat. Cold? It can chill.

How about 22 soccer players sprinting, kicking and sliding their way across it at the 2022 World Cup, all amid the desert climate of the Middle East? Game on.

A commercial variety of seashore paspalum has padded every pitch in Qatar. There, it’s withstood every steel-cleated footfall of Messi, Mbappé and Neymar, every sunbeaten day of temperatures creeping into the high 80s Fahrenheit.

Thanks to a new study led by the University of Nebraska–Lincoln, seashore paspalum may soon assist another goal: growing crops that yield more food with less of the fertilizer that imposes costs on farmers, ecosystems and drinking water.

Global application of fertilizers, especially the nitrogen and phosphorous essential to plant growth, has skyrocketed since the mid-20th century, around the time a teenage Pelé was leading Brazil to its first World Cup title. As it turns out, seashore paspalum doesn’t need much of those nutrients, either. That sets it apart from some of its surprisingly close relatives: corn and sorghum, among other grass crops.

After sequencing the full genetic blueprints of the hardy grass, a multi-institution research team has discovered the bag of tricks behind the plant’s fasting technique. What’s more, the researchers managed to recreate those tricks in corn seedlings, which responded by growing faster and larger than other, unmodified seedlings deprived of the nutrients.

“We finally are starting to understand just what makes this plant so resilient,” said James Schnable, one of the study’s authors and Charles O. Gardner Professor of Agronomy at Nebraska.

The species really began intriguing Schnable and his colleagues after an impressive showing at the Nebraska Innovation Greenhouse, where it seemed not to care that its caretakers were neglecting it.

“There was a period where no one remembered to water the paspalum plant for a couple of months,” Schnable said. “But the plant was completely fine. In fact, it usually grows so fast that it’ll try to invade the pots of neighboring plants, and the greenhouse manager has to yell at me or folks in my lab to come down and trim it.”

Guangchao Sun, a doctoral alumnus and former postdoc at Nebraska, took notice, too. He decided to put seashore paspalum’s resilience to the test with an experiment, growing it alongside corn and sorghum for several weeks under multiple conditions. When the corn and sorghum were denied nitrogen or phosphorous, their stunted development betrayed it. The seashore paspalum, meanwhile, continued “happily growing.”

Fortunately, the Schnable lab was also working with the Department of Energy’s Joint Genome Institute, the University of Georgia and the HudsonAlpha Institute for Biotechnology on mapping the species’ genome. Those strides cleared the way to studying seashore paspalum’s tolerance in greater detail.

Analyses of its genes and gene expression later revealed that the grass responds to a lack of nutrients by roughly doubling its production of a sugary molecule called trehalose. Though corn and sorghum naturally churn out some of that molecule, the team saw no change in its production among the two nutrient-starved crops.

While the finding suggested that trehalose was playing a central role in the plant’s resilience, Sun and the team pressed on for evidence that could meet a higher burden of proof. What if, they thought, we could increase trehalose in corn, then observe the results? But applying trehalose directly to the crop proved ineffective.

“So I thought about it in the opposite way,” said Sun, who now works as a bioinformatician at the Mayo Clinic. “If I cannot supply trehalose to the plants, what if I stopped its degradation in those plants?”

He turned to an antibiotic that can inhibit the enzyme responsible for degrading trehalose. The plan worked: Curbing the enzyme cranked up the trehalose levels in the corn. Within days, he noticed the crop growing more — regardless of whether it was nutrient-deprived. The results were so startling to Sun that he soon repeated the experiment multiple times. Each time, the corn responded the same way.

But the team had reason to suspect that the tolerance also relied on autophagy — what Schnable called “a recycling program” in plant cells that takes apart old or damaged proteins, then reassembles them into fresh, functioning ones. Eventually, the researchers developed a mutant of corn that lacked the ability to engage the final stage of that recycling. Even with a surplus of trehalose, the mutant failed to thrive when deprived of nitrogen or phosphorous, marking autophagy as an equally essential facet of the resilience.

“There are still other things to do,” Sun said, before the team resolves the complete picture of seashore paspalum’s world-class tolerance. He considers it only a matter of time, though, before researchers identify the genes that code for higher trehalose.

“And if you could (introduce) that genomic region into other elite corn varieties — say, some maize that has high yield but is really sensitive to nutrient stress — maybe now you get both a high yield and high resilience,” he said.

For now, Sun said he’s glad to bask in the team’s accomplishment. In true World Cup fashion, learning that the team’s study had been accepted for publication in Nature Communications brought on a few tears, a few hugs. And why not? Qualification for the 2022 World Cup may have kicked off in 2019, but the research team embarked on its project a year earlier.

“This was a long, long journey,” Sun said. “Honestly, it increased my resilience, too.”

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JOURNAL

Nature Communications

DOI

10.1038/s41467-022-35507-8 

Taking pride in identity may protect mental health against online hate, experience of Asian Americans finds

Peer-Reviewed Publication

TAYLOR & FRANCIS GROUP

Feeling proud of your background is key to one’s mental health when dealing with online racism, a new study in the Journal of Applied Communication Research suggests. 

 

Identity affirmation was linked to better psychological health in Asian Americans who were faced by a rise in online hate speech at the start of the Covid pandemic. 

 

Being proud of who you are and what you stand for, a form of resilience, was also associated with better physical health, better personal relationships and greater satisfaction with living circumstances. 

 

“Online hate speech attacks deep components of human identity and so may have sparked people’s need to reaffirm core elements of who they are,” says researcher Stephanie Tom Tong, an associate professor of communication studies at Wayne State University in the US.   

 

“This may have offered them comfort, provided them with meaning or helped guide their behaviour, making them more able to protect themselves against the damaging effects of online racial harassment.” 

 

Hate speech directed at Asians has surged during Covid, with many Americans following Donald Trump’s lead in blaming China for starting the pandemic.   

 

Research has shown that 30% of Americans believe China or Chinese people are responsible for the virus and that anti-Asian hate speech has increased ten-fold on platforms such as Twitter. 

 

It wasn’t clear, however, to what extent people in the US were aware of the rise, considering that it occurred against a backdrop of Covid-related job losses, illness and bereavement. 

The increase in online hate speech may also have been masked by the long-standing perception of Asian Americans as being a “model minority” that leads problem-free, successful lives, untouched by racism.   

Recent research into race in America found that people were more likely to think that being Asian helped someone get ahead, than hinder them. However, the majority of Asian Americans who took part in the poll said they’d experienced discrimination or unfair treatment because of their ethnicity. 

Dr Tong surveyed 1,767 Americans, including 455 Asian Americans, in May 2020 about whether they thought there had been a rise in the amount of anti-Asian hate speech appearing online during the pandemic.   

 

The respondents were also questioned about their health and whether they had engaged in identity affirmation and other forms of resilience to help them cope with the stress of the pandemic. 

 

Resilience is defined as the ability to bounce back from, or adapt to, stressful or traumatic experiences that disrupt the normal flow of life.   

 

The Asian Americans perceived there to be a greater increase in online hate speech and were more likely to show resilience. 

 

This could be through identity affirmation, creating new routines, making an effort to maintain social networks, reframing stressful situations or trying to move forward with their lives. 

 

People who showed resilience in the face of online racism were also more likely to say they were in better physical health, have better personal relationships and be more satisfied with their living circumstances. 

 

The authors acknowledge that they weren’t able to prove causation and it is also possible that people who are in better mental health are more likely to practice resilience and to be more empathic and aware of the plight of others. 

 

They do, however, believe that learning how to be more resilient could be key to coping with online racism and call on the US government to commit more resources to culturally appropriate mental health services, particularly those that teach resilience. Stigma, language and access barriers and differences in values mean existing services tend to be under-used by Asian Americans. 

 

They add that although they focused on the rise in online racial hate speech during the pandemic, they hope that their results will be of wider relevance. 

 

“While coronavirus has impacted society on multiple fronts – health, social, economic and political – one of the most heinous fallouts has been the racial hate speech directed at people of Asian origin,” says Dr Tong. 

 

“Online hate speech is, however, a worldwide problem and we are optimistic that fostering resilience will help people bounce back from it.” 

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JOURNAL

Journal of Applied Communication Research

DOI

10.1080/00909882.2022.2141068 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Racism and resilience of pandemic proportions: Online harassment of Asian Americans during COVID-19

ARTICLE PUBLICATION DATE

16-Dec-2022

Poorer physical health among those who experience discrimination in Canada

More than 90% of refugees, immigrants and racialized Canadians aged 15-64 are in good physical health, but those who experienced discrimination, those with poor mental health, the unmarried and men did not fare as well

Peer-Reviewed Publication

UNIVERSITY OF TORONTO

With the projected influx of refugees coming to Canada, particularly with global crises such as the war in Ukraine, it is imperative to understand the health outcomes of refugees who settle in Canada.

A new study from the University of Toronto has suggested that the health of working age refugees — aged 15-64 — is similar to that of immigrants and Canadian-born individuals. More than nine out of ten of the refugees, many of whom arrived in Canada decades earlier, reported good health. These findings are in contrast to previous research in the US and elsewhere that has suggested poorer physical health outcomes among refugees, compared to those born within the host country.  It is possible that Canada’s universal health coverage may have contributed to the positive health outcomes among refugees in the study.

Overall, race also did not seem to be a factor in physical health outcomes, with nine in ten racialized Canadians reporting good physical health, which was comparable to the White population.

One of the study’s key findings related to the interaction between discrimination and health. Approximately 40% of refugees and immigrants and one-third of those born in Canada reported they had experienced some form of discrimination (e.g., racism, sexism, ageism) in the past 5 years. Refugees, immigrants, and the Canadian-born respondents who had not experienced discrimination had almost double the odds of reporting good health.

“Although the high prevalence of good physical health among refugees and immigrants is very encouraging, the strong link we found between discrimination and poor health underlines the importance of anti-discrimination strategies and trainings in healthcare and workplace settings.” said first author, Alyssa McAlpine, a recent MSW graduate of the Factor-Inwentash Faculty of Social Work (FIFSW) at the University of Toronto.

Good mental health was the strongest factor associated with good physical health.  Only 1 in 5 refugees in poor mental health had good physical health compared to 94% of refugees who were in good mental health.

“Our findings highlight that the mind and body is a continuum. It is important that doctors, social workers, and other health professionals screen for mental illness and refer those who are struggling for treatment. There is strong evidence that a particular form of talk therapy called cognitive behavioral therapy is very efficacious with refugees as well as the general population” said senior author, Esme Fuller-Thomson, a professor at FIFSW and director of the Institute for Life Course & Aging at the University of Toronto. 

Social support networks were also associated with physical health. Those who belonged to social groups or associations and those who were married were more likely to be in good physical health.

“Overall, our findings suggest the importance of promoting programs to improve social networks and opportunities for refugees” explained co-author Professor Usha George, Academic Director, Toronto Metropolitan Centre for Immigration and Settlement. “Greater social integration may be protective to the health of refugees, particularly those who are socially isolated.”

Additionally, among refugees, women were more likely to report good physical health. In contrast, among immigrants, men had a higher prevalence of good physical health and among those born in Canada there were no sex-differences in self-reported physical health.

Data within the study was retrieved from Statistics Canada’s nationally representative 27th General Social Survey (GSS-27). In total, there were 17,082 respondents between the ages of 15-64, which included refugees (n=753), immigrants (n=5,063), and Canadian-born individuals (n=11,266). This paper was published in Advances in Public Health.  The study was supported by the Social Science and Humanities Research (Grant number:435-2020-0177; PI Esme Fuller-Thomson).

This publication is dedicated to co-author, Dr. Karen Kobayashi of the University of Victoria, Canada, who passed away on May 28, 2022. She devoted her career to improving the well-being of immigrants in Canada and to mentoring the next generation of immigration scholars.

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JOURNAL

Advances in Public Health

DOI

10.1155/2022/9429242 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Self-Reported Health of Working-Age Refugees, Immigrants, and the Canadian-Born

Wood-eating clams use their poop to dominate their habitat

Peer-Reviewed Publication

FIELD MUSEUM

 

IMAGE: BOREHOLES DUG BY THE WOOD-BORING CLAMS. THE CLAMS FILL THESE BOREHOLES WITH THEIR OWN POOP, MAKING THE SUNKEN WOOD AN INHOSPITABLE ENVIRONMENT FOR OTHER SPECIES. view more 

CREDIT: MEG DALY

Deep beneath the waves, tiny clams with shells usually about as big as a pea bore into pieces of sunken wood. The wood is food for them, as well as a home. These rare, scattered, sunken pieces of wood support miniature ecosystems where different wood-boring clam species can live in harmony for years. But in a new paper in Marine Biodiversity, researchers found that one group of wood-boring clams has evolved a unique way to get the wood all for itself: building chimneys made of poop.

“There are two challenges every sea creature has to face: getting pure water in, so you can get oxygen to your gills, and getting rid of your waste. Because nobody wants to live in their poop. But here are these clams living with theirs, and actually thriving,” says Janet Voight, Associate Curator of invertebrate zoology at the Field Museum and the study’s lead author.

Scientists can put wood on the seafloor, return months or even years later, and recover it with “an amazing array of animals,” says Voight; other times wood that has been submerged for the same amount of time comes up so gnawed and bored-through that you can crumble it in your hand. This difference was a mystery, and Voight wanted to know why.

She took stock of the wood-boring clam species present in reports of sunken wood from all over the world, and she noticed a pattern. “There are six main branches in the wood-boring clam family tree, and every woodfall that was bored so heavily it was crushable by hand turned out to have been bored by a species from the same single branch of that family tree,” says Voight. She says she was surprised by this finding-- “that’s not supposed to happen, you just assume that all wood-boring clam species, which tend to look pretty similar, bore into wood the same way. And yet, here’s one group that’s doing something totally different.”

Scientists had suggested that the extra-chewed-up wood was due to lots of larvae happening to be present nearby, or warmer water temperatures, but it turns out, the very nature of the clams may be responsible. Voight noted all of these extra-efficient, related species have a common trait where the sun don’t shine. As the clams dig and move into their boreholes in the wood, they fill the space around them inside the holes with their own feces.

“They don’t do it on purpose, their anatomy makes them do it,” says Voight. “When these clams bore into wood, their little shell does the boring.” Meanwhile, the clams’ siphons, tubular appendages for taking in water to get oxygen and expelling waste, stick out behind them. “In most wood-boring clams, these two “in and out” siphons are equal in length and stick out into the water column,” says Voight. “But in these related hyper-nasty borers, the siphon for expelling de-oxygenated water and feces is short; it stays inside the borehole in the wood. As a result, says Voight, “they poop in their borehole. They just have to, unless they really, really push.” The waste stays right there with the clam, forming a chimney that wraps around the siphon.

That animals would evolve an anatomy that keeps them in such close contact with their own waste, is surprising, says Voight: “It sure isn’t very hygienic, and yet they show no evidence of immune problems. They're healthy, they're clearly going to town on the wood. So why did they evolve this way?”

She and her colleagues hypothesized that these fecal chimneys might cue larval settlement: that their free-floating larvae might be able to detect the poop and make their way to it to make a home alongside members of their own species.

But that still leaves the problem: even if a poop chimney serves as a beacon for other members of their species to join them on their wood, how can these individuals survive as more and more larvae settle and the environment becomes filthier and oxygen becomes less available?

“This group of species of clam has been shown in previous studies to be unusually tolerant of low oxygen,” says Voight. They also have additional adaptations, like a mucosal lining of their fecal chimneys, and a substance like hemoglobin in their blood that picks up more oxygen; both may reduce the risk of sulfide poisoning from the waste. Taken together, these adaptations allow these species to survive in conditions that would make non-related wood-boring clams sick. The end result is more wood for the chimney-producing species to eat, live in, and for their offspring to settle on, unbothered by competitors.

Beyond just solving the mystery of the gross chewed-up wood with an even grosser solution, Voight says that the study illustrates the importance of looking at ecology with an understanding of how different species are related to each other.

“When you’re confronted with something that seems enigmatic, sometimes you need to step back and look at the big picture, put a lot of different studies together, to see how what had appeared to be enigmatic is a product of evolution,” says Voight. “Having a good family tree can help reveal patterns, and the more we know about the evolutionary histories of these different groups, the more we’ll be able to find out about how they fit together.”

###

  

Wood retrieved from the ocean floor that's been so thoroughly chewed up by the clams that you can crumble it with your hand.

CREDIT

Kate Golembiewski, Field Museum

JOURNAL

Marine Biodiversity

DOI

10.1007/s12526-022-01306-z 

ARTICLE TITLE

Competition in the deep sea: phylogeny determines destructive impact of wood-boring xylophagaids (Mollusca: Bivalvia)

ARTICLE PUBLICATION DATE

15-Dec-2022

Measuring the stress of moving house

Moving is considered stressful, but just how stressful is it? University of Auckland researchers have developed an original method of investigation.

Peer-Reviewed Publication

UNIVERSITY OF AUCKLAND

University of Auckland Business School researcher Dr William Cheung is analysing micro-level data about people and households to examine the effects of moving house on mental well-being and stress.

His study, co-authored with business analyst Daniel Wong scrutinises stress levels among adults in the Auckland region, namely homeowners and renters, alongside a control group of non-movers. Overall, the results show that the average stress level of homeowners is significantly higher than renters, and those who move more frequently are more stressed than those who don't. The data also suggests that individuals dealing with high stress levels are predisposed to move house.

While acute stresses seem to result in one-off movements, Dr Cheung says chronic stresses result in more frequent movement. The study also shows that stress levels decrease over time when individuals don't move. Cheung says social housing tenants have much higher baseline stress levels than both homeowners and renters.

While research has shown that moving house is detrimental to mental well-being," Dr Cheung says in his paper, "our studies further suggest that frequent relocation and the housing tenure types, especially owner-occupier, is a substantial contributor to stress."

As a result, the study's authors recommend implementing housing strategies that ensure housing can be sustained over time. Dr Cheung says this may include assistance programmes that make housing more attainable for the vulnerable, such as those encountering mental illness. "We need economic programmes that aid individuals at risk of losing their homes and, as well as providing stable housing, mental health services must be available, easily accessible among urban residents, and designed to remain amenable under transient circumstances."

The average stress levels of non-movers, renters, homeowners, and social housing residents aged between 19 and 54 living in urban Auckland between 2013 and 2018 were analysed by Cheung and Wong using the government's Integrated Data Infrastructure, which is based on micro-level individual census data.

This census data enabled them to reconstruct what's known as the Social Readjustment Rating Scale (SRRS), a stress comparison scale developed in the 1960s by two psychiatrists. The original SRRS attributes up to 100 points to different life stressors, ranging from 100 points for a spouse's death to 11 points for minor law violations. Other examples include moving house (20 points), incurring a large mortgage (37) and divorce (73 points).

Dr Cheung says the new method resulted in an instrument that can measure the socioeconomic impact on an individual in any population segment far more cost-effectively than current measures. Using the census data and the SRRS model also proved more efficient than conventional surveys, with better sensitivity and an increased ability to identify influences on the individual.

"We advanced our understanding of the stress of moving homes; the influence of mobility on place experience; and the circumstances, advantages and challenges of moving home over a resident's lifetime." By progressing people's understanding of such stressors, Dr Cheung says researchers can contribute to broader discussions on how an individual's personal history and social mobility influence their social well-being. 

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JOURNAL

Urban Science

DOI

10.3390/urbansci6040075 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Measuring the Stress of Moving Homes: Evidence from the New Zealand Integrated Data Infrastructure

HKU Mechanical Engineering team develops new microscale 3D printer for multi-level anticounterfeiting labels

Peer-Reviewed Publication

THE UNIVERSITY OF HONG KONG

 

IMAGE: DR JI TAE KIM (LEFT) AND DR JIHYUK YANG (RIGHT) view more 

CREDIT: THE UNIVERSITY OF HONG KONG

Counterfeiting threatens the global economy and security. According to the report issued by the United States Patent and Trademark Office (USPTO) in 2020, the value of global counterfeit and pirated products is estimated between US$ 1.7 and 4.5 trillion a year. Despite enormous efforts, conventional anticounterfeiting approaches such as QR codes can be easily fabricated due to limited data encryption capacity on a planar space. How can we increase the encryption density in a limited space?

The team led by Dr Ji Tae Kim from the Department of Mechanical Engineering at the University of Hong Kong (HKU) has developed a high-precision 3D printing method that can produce new polarisation-encoded 3D anticounterfeiting labels. This new 3D label can encrypt more digital information than a traditional 2D label. The work has been published in Nano Letters in an article entitled “Three-Dimensional Printing of Dipeptides with Spatioselective Programming of Crystallinity for Multilevel Anticounterfeiting”.

Diphenylalanine (FF), a species of dipeptides, was chosen as a material for data encryption due to its unique optical properties. Dr Jihyuk Yang from the Department of Mechanical Engineering, HKU, explained: “FF has long attracted great attention to neuroscientists due to its association with Alzheimer's disease. Recently, FF is emerging as a new electronic and photonic device material due to its unique properties – e.g. piezoelectricity and optical birefringence – arising from crystalline nature.” Dr Yang is the first author of the paper.

 “Our new 3D printing method combined with nature-driven molecular self-assembly can print multi-segmented 3D FF micro-pixels with programmed crystallinity for high-density data encryption. By utilising different responses of the amorphous and crystalline segments to polarised light, a tiny single 3D pixel can encrypt a multi-digit binary code consisting of "0" and “1". The information capacity can be increased to 211 with a single eleventh-segmented freestanding pixel on a tiny 4 µm2 area which is 1000 times smaller than a hair strand,” said Dr Ji Tae Kim. He believes that 3D printing technology can be effectively used to customise security labels on-demand anywhere and anytime, contributing to strengthening the information security of individuals and companies.

Link to the journal article: https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.2c01761

Scheme: 3D printing process of polarization-encoded 3D micro-pixels

CREDIT

The University of Hong Kong

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JOURNAL

Nano Letters

DOI

10.1021/acs.nanolett.2c01761 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Three-Dimensional Printing of Dipeptides with Spatioselective Programming of Crystallinity for Multilevel Anticounterfeiting

Catalyzing ‘net-zero’ green hydrogen from the sun: HKU chemists discover a fundamental catalyst protonation process to promote solar-driven water-splitting for hydrogen production without CO2 emissions

Peer-Reviewed Publication

THE UNIVERSITY OF HONG KONG

 

IMAGE: CHEMISTS AT HKU DISCOVER A FUNDAMENTAL CATALYST PROTONATION PROCESS TO ENHANCE PRODUCTIVITY OF SOLAR-DRIVEN WATER-SPLITTING FOR HYDROGEN BY EIGHT TIMES, CATALYSING GREEN ENERGY WITHOUT CO2 EMISSIONS. view more 

CREDIT: THE UNIVERSITY OF HONG KONG

Hydrogen is a promising green energy carrier for a sustainable future. However, it is mostly locked in water. Energy is required to liberate it from water for practical use. Solar energy is abundantly renewable, ideal for direct water-splitting to generate hydrogen using a ‘photocatalyst’. However, despite of considerable effort, practical adoption has been slow due to relatively low efficiency and high cost of the catalyst.

A research team led by Professor Zheng-Xiao GUO and Professor David Lee PHILLIPS from the HKU-CAS Joint Laboratory on New Materials and the Department of Chemistry of The University of Hong Kong (HKU), has reported the discovery of an important in-situ protonation process that the photodynamics and separation of charge carriers in a photocatalyst, leading to efficient hydrogen generation from water using visible solar light. The process is enabled in an interstitial phosphorus doped carbon nitride structure, with only earth-abundant non-metallic elements, for its cost-effectiveness and high potential for practical applications. The research findings are recently published online in a top scientific journal, Energy & Environmental Science.

Background and Achievement
Extensive research efforts have been devoted to the development of photocatalysts for solar-driven energy conversion with improved activity, efficiency and durability, mostly via: charge separation, transfer and utilisation. However, the complex multi-electron transfer, proton coupling and intermediate dynamics can all influence the photocatalytic pathway, kinetics and efficiency, which have not been well understood. It is thus highly desirable to foster in-depth investigations integrating innovative synthesis design, microscopic and spectroscopic characterisations and atomic simulations at the molecular level.

With full appreciation of the current efforts and the challenges in photocatalysis, the HKU team examined the fundamental issues from a different angle and proposed a new fundamental process of a proton-mediated photocatalytic mechanism to enhance the photo-dynamics, charge separation and hence the overall efficiency of an interstitial phosphorus-doped carbon-nitride, g-C3N4. The in-situ proton-mediated mechanism points to a new role of the water molecule, not just as a solvent or reactant but as an effective band-structure modifier of the catalyst in the overall design of effective photocatalytic processes.

In essence, the team has developed an effective atomic heterojunction by porosity-stabilised interstitial P-doping and in-situ protonation to induce shallow trap states, which effectively: a) enhance the lifetime of the excited states and b) restrain undesirable deep charge trapping, leading to efficient water decomposition. For the first time, the team has identified that the in-situ protonation of an interstitially anchored phosphorus in a holey g-C3-xN4 is a very effective structural configuration of the catalyst for highly efficient and stable visible-light hydrogen generation.

‘We expect that our discovery will open up a new line of thinking in the future design of photocatalysts for effective solar energy utilisation, by paying more attention to operando structural dynamism as a viable handle to pump up the conversion efficiency,’ said Professor Zheng-Xiao Guo.

‘Spectroscopic investigations show a colourful world of nanomaterials, and it will cast more light on the mechanistic insights of science and technologies,’ echoed Professor David Lee Phillips.

About Professor Zheng-Xiao Guo
Professor Zheng-Xiao Guo is a joint-faculty Professor of Chemistry and Mechanical Engineering at HKU, an Honorary Professor at the University College London (UCL), an Elected Member of Academia Europaea (The Academy of Europe), as well as a Fellow of the Royal Society of Chemistry and a Fellow of the Institute of Materials, Minerals and Mining. He was a Professor of Chemistry at UCL (2007-18), and prior to this, a Lecturer (1995-98), Reader (1998-99) and Professor (2000-07) at Queen Mary, the University of London. He was a research fellow at the University of Oxford (1990-95), and of Strathclyde (1988-90), respectively, with a PhD and an MRes from the University of Manchester in 1988 and 1984, and a BEng in Materials Science from the Northeastern University/China in 1983, respectively.

More information about his research group: https://zxguo.hku.hk/

About Professor David Lee Phillips
Professor David Lee Phillips is a Chair Professor at HKU Department of Chemistry. As an internationally recognised chemist, he uses time-resolved spectroscopy experiments and quantum mechanical calculations to study short-lived intermediates in chemical reactions of interest in chemistry, biology and the environment. He has published more than 350 internationally refereed scientific journal articles listed in Science Citation Index.

He serves on the Editorial Advisory Board of the journal Molecules and also on the Advisory Board of the Journal of Physical Organic Chemistry. Professor Phillips graduated with a PhD from the University of California, Irvine.

More information about his research group: https://sites.google.com/view/dlplab/home?pli=1

About the Research Team
Dr Wenchao WANG (Postdoctoral fellow) from Professor Guo’s group is the first author. Professor Lili DU from the Jiangsu University, Professor Hung Kay LEE from the Chinese University of Hong Kong and other HKU researchers (including Miss Ruiqin XIA; Dr Runhui LIANG; Mr Tao ZHOU; Dr Zhiping YAN; Miss Hao LUO; Dr Congxiao SHANG) in the Department of Chemistry contributing to the research.

Supplementary Information
W. Wang, L. Du, R. Xia, R. Liang, T. Zhou, H. K. Lee, Z. Yan, H. Luo, C. Shang, D. L. Phillips,* Z. X. Guo* “In-situ protonated-phosphorus interstitial doping induces long-lived shallow charge trapping in porous C3-xN4 photocatalyst for highly efficient H2 generation” (2022) Energy Environ. Sci. (DOI: https://doi.org/10.1039/D2EE02680E)

The research paper can be accessed here: https://pubs.rsc.org/en/content/articlelanding/2023/ee/d2ee02680e

This work was supported by the Hong Kong RGC-EU Collaborative Programme initiative, the HK Environment and Conservation Fund, RGC-GRF, the Natural Science Foundation of Zhejiang Province, the Key-Area Research and Development Program of Guangdong Province, the Joint Laboratory Funding Scheme, the “Hong Kong Quantum AI Lab Ltd” funded by the AIR@InnoHK, launched by the Innovation and Technology Commission (ITC), the URC Platform Technology Fund, the start-up support from the University of Hong Kong, and HKU Libraries’ Open Access Author Fund.

Image download and caption: https://www.scifac.hku.hk/press

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JOURNAL

Energy

DOI

10.1039/D2EE02680E 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

In situ protonated-phosphorus interstitial doping induces long-lived shallow charge trapping in porous C3−xN4 photocatalysts for highly efficient H2 generation

ARTICLE PUBLICATION DATE

5-Dec-2022