In Physics of Fluids, from AIP Publishing, University of Ottawa researchers Ezgi Pulatsu and Chibuike Udenigwe identify a range of factors that affect the print quality and shape complexity of food created with additive manufacturing. Accounting for these features can increase food quality, improve control, and speed up printing.

Additive manufacturing of food involves designing (3D shapes and their geometric codes), pre-processing (food ink preparation), manufacturing (deposition of layers to create shapes), and post-processing (baking, boiling, cooking, freezing, frying, or drying). Each step is an opportunity to create innovative foods.

Changing the printing patterns and ingredients of the initial mix or paste can affect the food’s matrix and microstructures and therefore its texture.

The flow of that mix in additive manufacturing is also crucial and is sometimes encouraged or discouraged by controlling ingredients and process conditions.

“Extrusion-based 3D printing is the most applicable technique for food,” said Pulatsu. “It involves a syringe loaded with a food paste – such as puree, dough, or frosting – being forced out of a nozzle by direct (pushing the plunger) or indirect force (compressed air).”

Creating a stable continuous flow is the first step to successful printing, so designed shapes can be produced by layering stringlike material in a controlled way.

“Once a layer is deposited, we no longer want it to flow; otherwise, it will destroy the shape we created,” said Pulatsu.

Post-processing – through baking, boiling, cooking, freezing, frying, or drying – physically and chemically transforms the food’s micro- and macromolecules and leads to various textures and tastes. At the same time, the shape should be conserved or carefully controlled.

“We also have other mechanisms of creating food structures via different 3D-printing techniques,” Pulatsu said. “For example, material jetting uses liquid binders deposited on powder to form self-supporting layers, and liquid inks that harden after deposition can also be used.”

One way to make additive manufacturing more efficient for the food industry is by establishing a printing path (a series of computer-controlled movements), which is often skipped for food applications.

“Future studies should explore the cost efficiency of different technologies in terms of build time, where shape complexity and toolpath strategies – which involve the printing path, moving head speed, and nonprinting movements – are also considered,” said Pulatsu. “Food is essential to living, and it’s becoming more critical due to the increasing global population and environmental changes. Therefore, novel foods and matrices should be designed in consultation with chefs, food scientists, and engineers, and in line with current needs.”

The results of the experiments, aided by the insights of theoretical physicists at Rutgers, could play a role in the development of revolutionary technologies and devices.

“It’s likely that that quantum materials will drive the next generation of technology and that strange metals will be part of that story,” said Piers Coleman, a Distinguished Professor at the Rutgers Center for Materials Theory in the Department of Physics and Astronomy at the Rutgers School of Arts and Sciences and one of the theoreticians involved in the study. “We know that strange metals like Y-ball exhibit properties that need to be understood to develop these future applications. We’re pretty sure that understanding this strange metal will give us new ideas and will help us design and discover new materials.”

Reporting in the journal Science, an international team of researchers from Rutgers, the University of Hyogo and the University of Tokyo in Japan, the University of Cincinnati and Johns Hopkins University described details of electron motion that provide new insight into the unusual electrical properties of Y-ball. The material, technically known as the compound YbAlB₄, contains the elements ytterbium, aluminum and boron. It was nicknamed “Y-ball” by the late Elihu Abrahams, founding director of the Rutgers Center for Materials Theory.

The experiment revealed unusual fluctuations in the strange metal’s electrical charge. The work is groundbreaking, the researchers said, because of the novel way the experimenters examined Y-ball, firing gamma rays at it using a synchrotron, a type of particle accelerator.

The Rutgers team — including Coleman, fellow physics professor Premala Chandra and former postdoctoral fellow Yashar Komijani (now an assistant professor at the University of Cincinnati) — have spent years exploring the mysteries of strange metals. They do so through the framework of quantum mechanics, the physical laws governing the realm of the ultra-small, home of the building blocks of nature such as electrons.

Analyzing the material using a technique known as Mossbauer spectroscopy, the scientists probed Y-ball with gamma rays, measuring the rate at which the strange metal’s electrical charge fluctuates. In a conventional metal, as they move, electrons hop in and out of the atoms, causing their electrical charge to fluctuate, but at a rate that is thousands of times too fast to be seen by Mossbauer spectroscopy. In this case, the change happened in a nanosecond, a billionth of a second.

“In the quantum world, a nanosecond is an eternity,” said Komijani. “For a long time, we have been wondering why these fluctuations are actually so slow.” “We reasoned,” continued Chandra, “that each time an electron hops into an ytterbium atom, it stays there long enough to attract the surrounding atoms, causing them to move in and out. This synchronized dance of the electrons and atoms slows the whole process so that it can be seen by the Mossbauer.”

They moved to the next step. “We asked the experimentalists to look for these vibrations,” said Komijani, “and to our delight, they detected them.”

Coleman explained that when an electrical current flows through conventional metals, such as copper, random atomic motion scatters the electrons causing friction called resistance. As the temperature is raised, the resistance increases in a complex fashion and at some point it reaches a plateau.

In strange metals such as Y-ball, however, resistance increases linearly with temperature, a much simpler behavior. In addition, further contributing to their “strangeness,” when Y-ball and other strange metals are cooled to low temperatures, they often become superconductors, exhibiting no resistance at all.

The materials with the highest superconducting temperatures fall into this strange family. These metals are thus very important because they provide the canvas for new forms of electronic matter — especially exotic and high temperature superconductivity.

Superconducting materials are expected to be central to the next generation of quantum technologies because, in eliminating all electrical resistance, they allow an electric current to flow in a quantum mechanically synchronized fashion. The researchers see their work as opening a door to future, perhaps unimaginable possibilities.

“In the 19th century, when people were trying to figure out electricity and magnetism, they couldn’t have imagined the next century, which was entirely driven by that understanding,” Coleman said. “And so, it’s also true today, that when we use the vague phrase ‘quantum materials,’ we can’t really envisage how it will transform the lives of our grandchildren.”

If all the lost ice was piled on London, it would stand over 2 km tall - or 7.4 times the height of the Shard. If it were to cover Manhattan, it would stand at 61 km - or 137 Empire State Buildings placed on top of one another. 

Twenty major glaciers form the Amundsen Sea Embayment in West Antarctica, which is more than four times the size of the UK, and they play a key role in contributing to the level of the world’s oceans.  

 So much water is held in the snow and ice, that if it were to all to drain into the sea, global sea levels could increase by more than one metre.  

The research, led by Dr Benjamin Davison at the University of Leeds, calculated the “mass balance” of the Amundsen Sea Embayment. This describes the balance between mass of snow and ice gain due to snowfall and mass lost through calving, where icebergs form at the end of a glacier and drift out to sea.

When calving happens faster than the ice is replaced by snowfall, then the Embayment loses mass overall and contributes to global sea level rise. Similarly, when snowfall supply drops, the Embayment can lose mass overall and contribute to sea level rise.

The results show that West Antarctica saw a net decline of 3,331 billion tonnes of ice between 1996 and 2021, contributing over nine millimetres to global sea levels.  Changes in ocean temperature and currents are thought to have been the most important factors driving the loss of ice. 

Dr Davison, a Research Fellow at the Institute for Climate and Atmospheric Science at Leeds, said: “The 20 glaciers in West Antarctica have lost an awful lot of ice over the last quarter of a century and there is no sign that the process is going to reverse anytime soon although there were periods where the rate of mass loss did ease slightly. 

“Scientists are monitoring what is happening in the Amundsen Sea Embayment because of the crucial role it plays in sea-level rise. If ocean levels were to rise significantly in future years, there are communities around the world who would experience extreme flooding.” 

The research has been published in the scientific journal Nature Communications.

Extreme snowfall events

Using climate models that show how air currents move around the world, the scientists identified that the Amundsen Sea Embayment had experienced several extreme snowfall events over the 25-year study period. 

These would have resulted in periods of heavy snowfall and periods of very little snowfall or a “snow drought.”  

The researchers factored these extreme events into their calculations. Surprisingly, they found that these events contributed up to half of the ice change at certain times, and therefore played a key role in the contribution the Amundsen Sea Embayment was making to sea level rise during certain time periods.  

For example, between 2009 and 2013, the models revealed a period of a persistant snow drought. The lack of snowfall starved the ice sheet and caused it to lose ice, therefore contributing about 25% more to sea level rise than in years of average snowfall. 

In contrast, during the winters of 2019 and 2020 there was very heavy snowfall. The scientists estimated that this heavy snowfall mitigated the sea level contribution from the Amundsen Sea Embayment, reducing it to about half of what it would have been in an average year.  

Dr Davison said: “Changes in ocean temperature and circulation appear to be driving the long-term, large-scale changes in West Antarctica ice sheet mass.  We absolutely need to research those more because they are likely to control the overall sea level contribution from West Antarctica.  

“However, we were really surprised to see just how much periods of extremely low or high snowfall could affect the ice sheet over two to five-year periods — so much so that we think they could play an important, albeit secondary role, in controlling rates of West Antarctic ice loss.” 

Dr Pierre Dutrieux, a scientist at the British Antarctic Survey and co-author of the study, added: ”Ocean temperature changes and glacial dynamics appear strongly connected in this part of the world, but this work highlights the large variability and unexpected processes by which snowfall also plays a direct role in modulating glacier mass.”

New glacier named

The ice loss from the region over the past 25 years has seen the retreat of the Pine Island Glacier,  also known as PIG.

As it retreated, one of its tributary glaciers became detached from the main glacier and rapidly accelerated. As a result, the tributary glacier has now been named by the UK Antarctic Place-names Committee, Piglet Glacier, so that it can be unambiguously located and identified by future studies.  

Dr Anna Hogg, one of the authors of the paper and Associate Professor at the Institute of Climate and Atmospheric Science at Leeds, said: “As well as shedding new light on the role of extreme snowfall variability on ice sheet mass changes, this research also provides new estimates of how quickly this important region of Antarctica is contributing to sea level rise.  

“Satellite observations have showed that the newly named Piglet Glacier accelerated its ice speed by 40%, as the larger PIG retreated to its smallest extent since records began.”  

Satellites such as the Copernicus Sentinel-1 satellite, which uses sensors that ‘see’ through cloud even during the long Polar night, have transformed our ability to monitor remote regions. It is essential to have frequent measurements of change in ice speed and iceberg calving, so that we can monitor the incredibly rapid change taking place in Antarctica. 

However, they also found the process need more steps if the blended fabric was dyed or treated with chemicals that increase wrinkle resistance.

“We can separate all of the cotton out of a cotton-polyester blend, meaning now we have clean polyester that can be recycled,” said the study’s corresponding author Sonja Salmon, associate professor of textile engineering, chemistry and science at NC State. “In a landfill, the polyester is not going to degrade, and the cotton might take several months or more to break down. Using our method, we can separate the cotton from polyester in less than 48 hours.”

According to the U.S. Environmental Protection Agency, consumers throw approximately 11 million tons of textile waste into U.S. landfills each year. Researchers wanted to develop a method of separating the cotton from the polyester so each component material could be recycled.

In the study, researchers used a “cocktail” of enzymes in a mildly acidic solution to chop up cellulose in cotton. Cellulose is the material that gives structure to plants’ cell walls. The idea is to chop up the cellulose so it will “fall out” out of the blended woven structure, leaving some tiny cotton fiber fragments remaining, along with glucose. Glucose is the biodegradable byproduct of degraded cellulose. Then, their process involves washing away the glucose and filtering out the cotton fiber fragments, leaving clean polyester.

“This is a mild process — the treatment is slightly acidic, like using vinegar,” Salmon said. “We also ran it at 50 degrees Celsius, which is like the temperature of a hot washing machine.

“It’s quite promising that we can separate the polyester to a clean level,” Salmon added. “We still have some more work to do to characterize the polyester’s properties, but we think they will be very good because the conditions are so mild. We’re just adding enzymes that ignore the polyester.”

They compared degradation of 100% cotton fabric to degradation of cotton and polyester blends, and also tested fabric that was dyed with red and blue reactive dyes and treated with durable press chemicals. In order to break down the dyed materials, the researchers had to increase the amount of time and enzymes used. For fabrics treated with durable press chemicals, they had to use a chemical pre-treatment before adding the enzymes.

“The dye that you choose has a big impact on the potential degradation of the fabric,” said the study’s lead author Jeannie Egan, a graduate student at NC State. “Also, we found the biggest obstacle so far is the wrinkle-resistant finish. The chemistry behind that creates a significant block for the enzyme to access the cellulose. Without pre-treating it, we achieved less than 10% degradation, but after, with two enzyme doses, we were able to fully degrade it, which was a really exciting result.”

Researchers said the polyester could be recycled, while the slurry of cotton fragments could be valuable as an additive for paper or useful addition to composite materials. They’re also investigating whether the glucose could be used to make biofuels.

“The slurry is made of residual cotton fragments that resist a very powerful enzymatic degradation,” Salmon said. “It has potential value as a strengthening agent. For the glucose syrup, we’re collaborating on a project to see if we can feed it into an anaerobic digester to make biofuel. We’d be taking waste and turning it into bioenergy, which would be much better than throwing it into a landfill.”

The study, “Enzymatic textile fiber separation for sustainable waste processing,” was published in Resources, Environment and Sustainability. Co-authors included Siyan Wang, Jialong Shen, Oliver Baars and Geoffrey Moxley. Funding was provided by the Environmental Research and Education Foundation, Kaneka Corporation and the Department of Textile Engineering, Chemistry and Science at NC State.

Two of the studies, led by Pietro Lampertico, MD, PhD, Division of Gastroenterology and Hepatology, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy, were designed to assess the effectiveness and safety of patients with advanced HDV-related compensated cirrhosis being treated with BLV 2mg monotherapy and the consequences of discontinuing this treatment.

“HDV is the most severe form of chronic viral hepatitis,” explained Dr. Lampertico. “For many years, the only therapeutic option was the off-label administration of pegylated-interferon-alpha (PegIFNa), an approach characterized by suboptimal efficacy, an unfavorable safety profile and several contraindications.”

In a study of 18 patients with HDV-related advanced cirrhosis treated with BLV 2 mg/day for 48 weeks, Dr. Lampertico and colleagues demonstrated significant virological, biochemical and combined response rates associated with improvement of liver function.

“The efficacy and safety of BLV monotherapy in patients with advanced compensated cirrhosis were unknown before this study. Virological and biochemical responses to BLV monotherapy that we observed in our difficult-to-treat patients with HDV-related compensated cirrhosis were similar to those shown in the phase III registration study,” Dr. Lampertico noted.

In a case report, Dr. Lampertico and co-investigators demonstrated that HDV could be successfully eradicated from both serum and liver following a three-year course of BLV monotherapy, despite the persistence of HBsAg, in a patient with HDV-related compensated cirrhosis and esophageal varices. During the 72-week off-BLV follow-up, liver biopsy, intrahepatic HDV RNA and hepatitis D antigen were undetectable, less than 1% of hepatocytes were HBsAg positive and all were negative for hepatitis B core antigen.

“We were surprised to demonstrate that HDV can be eradicated following a finite course of an entry inhibitor administered as monotherapy such as BLV 2mg/day, despite the persistence of HBsAg positivity,” commented Dr. Lampertico.

In a study in JHEP Reports led by PD Dr. med. Katja Deterding, MD, Department. of Gastroenterology, Hepatology and Endocrinology at Hannover Medical School, Hannover, Germany, investigators report the first data from the largest multicenter cohort of patients to date who were treated with BLV under real-world conditions, including 50 patients with signs of significant portal hypertension, elevated pressure in the major vein that leads to the liver.

The retrospective analysis of 114 cases covered 4,289 patient weeks of BLV treatment. Viral response was observed in 87 cases while hepatic inflammation improved, and treatment was well tolerated. More than 50% of patients showed a virologic response with less than 10% of patients not achieving an HDV RNA drop of at least 90% after 24 weeks. An improvement of biochemical hepatitis activity as measured by the liver enzyme alanine transaminase (ALT) values was observed regardless of virologic response. Investigators concluded that treatment was safe and well tolerated and associated with improvements in liver cirrhosis and portal hypertension with prolonged treatment.

“In line with other real-world cohorts and clinical trials our real-world study confirms the antiviral activity of BLV,” noted Dr. Deterding. “We were surprised to see an improvement in biochemical hepatitis activity even in cases without viral response. Potential explanations for this phenomenon include anti-inflammatory properties of BLV.”

“This is the first time that patients with HDV-related chronic advanced liver disease can be treated with an antiviral therapy since 1977 when HDV was discovered. Long-term suppressive therapy with BLV 2 mg/day has the potential to improve survival, of these difficult-to-treat patients for the first time in 45 years,” concluded Dr. Lampertico. “We also found that BLV treatment can be successfully discontinued in some HDV patients who achieved long-term viral suppression while on therapy.”

HDV infection occurs when people become infected with both hepatitis B and D virus either simultaneously (co-infection) or acquire the hepatitis D virus after first being infected with hepatitis B (super-infection). According to the World Health Organization, HDV affects nearly 5% of individuals with a chronic infection resulting from hepatitis B virus (HBV). Populations that are more likely to have HBV and HDV co-infection include indigenous populations, recipients of hemodialysis and individuals who inject drugs.