Ancient concrete: Learning to do as the Romans did

A new look inside 2,000-year-old concrete — made from volcanic ash, lime (the product of baked limestone), and seawater — has provided new clues to the evolving chemistry and mineral cements that allow ancient harbor structures to withstand the test of time. The research has also inspired a hunt for the original recipe so that modern concrete manufacturers can do as the Romans did.

A team of researchers working at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) used X-rays to study samples of Roman concrete — from an ancient pier and breakwater sites — at microscopic scales to learn more about the makeup of their mineral cements.

The team’s earlier work at Berkeley Lab’s Advanced Light Source (ALS), an X-ray research center known as a synchrotron, found that crystals of aluminous tobermorite, a layered mineral, played a key role in strengthening the concrete as they grew in relict lime particles. The new study, published today in American Mineralogist, is helping researchers to piece together how and where this mineral formed during the long history of the concrete structures.

The work ultimately could lead to a wider adoption of concrete manufacturing techniques with less environmental impact than modern Portland cement manufacturing processes, which require high-temperature kilns. These are a significant contributor to industrial carbon dioxide emissions, which add to the buildup of greenhouse gases in Earth’s atmosphere.

Also, researchers suggest that a reformulated recipe for Roman concrete could be tested for applications such as seawalls and other ocean-facing structures, and may be useful for safeguarding hazardous wastes.

“At the ALS we map the mineral cement microstructures,” said Marie Jackson, a geology and geophysics research professor at the University of Utah who led the study. “We can identify the various minerals and the intriguingly complex sequences of crystallization at the micron scale.”

Jackson said that lime (also known as calcium oxide, or CaO) — exposed to seawater in the Roman concrete mixture — probably thoroughly reacted with volcanic ash early in the history of the massive harbor structures. Previous studies showed how the aluminous tobermorite crystallized in the lime remnants during a period of elevated temperature.

The new findings suggest that after the lime was consumed via these pozzolanic chemical reactions (so named for the volcanic ash found in the Pozzuoli, or Naples, region of Italy), a new period of mineral growth began.

The new growth of aluminous tobermorite is often associated with crystals of phillipsite, another mineral. The minerals form fine fibers and plates that make the concrete more resilient and less susceptible to fracture over time. They may explain an ancient observation by the Roman scientist Pliny the Elder, who opined that the concrete, “as soon as it comes into contact with the waves of the sea and is submerged, becomes a single stone mass, impregnable to the waves and every day stronger.”

In fact, the Romans relied on the reaction of a volcanic rock mixture with seawater to produce the new mineral cements. In rare instances, underwater volcanoes, such as the Surtsey Volcano in Iceland, produce the same minerals found in Roman concrete.

“Contrary to the principles of modern cement-based concrete,” Jackson said, “The Romans created a rock-like concrete that thrives in open chemical exchange with seawater.”

The ancient Roman recipe is very different than the modern one for concrete, Jackson noted. Most modern concrete is a mix of Portland cement — limestone, sandstone, ash, chalk, iron, and clay, among other ingredients, heated to form a glassy material that is finely ground — mixed with so-called “aggregates.” These are materials such as sand or crushed stone that are not intended to chemically react. If reactions do occur in these aggregates, they can cause unwanted expansions in the concrete.

To understand the long-term chemical processes that occurred in the Roman structures, researchers used thin, polished slices of the concrete with an electron microscope in Germany to map the distribution of elements in the mineral microstructures.

They coupled these analyses with a technique at Berkeley Lab’s ALS known as X-ray microdiffraction, and a technique at UC Berkeley known as Raman spectroscopy, to learn more about the structure of crystals in the samples.

Nobumichi Tamura, an ALS staff scientist, said the X-ray beamline where the Roman concrete samples were studied can produce beams focused to about 1 micron, or 1 thousandth of an inch, “which is useful for identifying each mineral species and mapping their distribution.” The beam is almost a hundred times smaller than what can be found in a conventional laboratory. The X-ray technique measures an average signal from many tiny mineral grains, providing high resolution and fast data collection.

Jackson added, “We can go into the tiny natural laboratories in the concrete, map the minerals that are present, the succession of the crystals that occur, and their crystallographic properties. It’s been astounding what we’ve been able to find.”

She added, “This is a concrete that apparently grows aluminum-tobermorite mineral cements over millennia.” The study suggests that this process could be useful for modern seawall structures, she said, as well as for encasing high-level wastes in cement-like barriers that protect the surrounding environment.

Jackson is working with a geological engineer to rediscover the Romans’ complex recipe for concrete. She is mixing seawater from the San Francisco Bay and volcanic rock from the Western United States to find the right formula, and is also leading a scientific drilling project to study the production of tobermorite and other related minerals at the Surtsey volcano in Iceland.

Already, a growing number of concrete manufacturers are exploring the use of volcanic rock and less energy-intensive processes, Jackson said, which could be a win-win for industry and the environment.

The concrete industry is big in the United States, with sales valued at about $50 billion in 2015. The nation’s production of Portland cement — the most commonly produced cement type — amounted to about 80.4 million tons in 2015, according to the U.S. Geological Survey, or roughly the weight of about 90 Golden Gate Bridges or 12 Hoover Dams.

In order for Roman concrete recipes to gain more traction, Jackson said, test structures will be needed to evaluate the long-term properties of marine structures built with volcanic rock and measure how they stack up against the properties of steel-reinforced concrete, for example.

“I think people don’t really know how to think about a material that doesn’t have steel reinforcement,” she said.

‘Perfect storm’ led to 2016 Great Barrier Reef bleaching

Researchers from James Cook University and the Université catholique de Louvain, Louvain-la-Neuve, Belgium say unprecedented oceanographic conditions in 2016 produced the perfect storm of factors that lead to a mass coral bleaching.

JCU’s Professor Eric Wolanski said even in very warm years with a summer el Nino event, such as 1998, there was no massive coral bleaching in the Torres Strait and only small to moderate bleaching in the northern Great Barrier Reef.

“So, the extensive coral bleaching in these areas during the summer of 2016 was an unwelcome surprise,” he said.

A 2016 aerial survey of the northern Great Barrier Reef lead by Professor Terry Hughes from JCU’s Center of Excellence for Coral Reef Studies showed that 90 per cent of reefs in some of these areas were severely bleached.

Professor Wolanski said satellite data showed the 2016 El Nino heating started in the Gulf of Carpentaria, with patches of water reaching an exceptionally high 34oC.

The water then flowed east onto the Torres Strait reefs and south to the Great Barrier Reef. The ‘residence time’ of the very warm water in the Torres Strait and the Northern Great Barrier Reef was exceptionally long, which increased the thermal stress on the coral.

All of these factors enabled local solar heating to proceed unrestricted.

“Examining surface currents suggests that the North Queensland Coastal Current in the Coral Sea, which would normally flush and cool the Northern Great Barrier Reef, actually did the opposite. It reversed course and brought very warm water to the Northern Great Barrier Reef.”

Professor Wolanski said these processes together made it the perfect thermal storm.

He said the study employed oceanography models used extensively to study water flow in the region, which were then calibrated with real oceanographic data.

Professor Wolanski said the study was subjective to the extent that there was a lack of oceanographic field data in the Great Barrier Reef itself for the 2016 el Nino event. By contrast, the amount of oceanographic field data in the Torres Strait and the northern Coral Sea was very good.

“What we presented is our best-informed attempt to reveal the mechanisms involved in causing the event, based on the available oceanographic data combined with the existing body of knowledge on the water circulation in and around the Torres Strait/Northern Great Barrier Reef region.”

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Materials provided by James Cook University. Note: Content may be edited for style and length.

Artificial bile ducts grown in lab and transplanted into mice could help treat liver disease

Cambridge scientists have developed a new method for growing and transplanting artificial bile ducts that could in future be used to help treat liver disease in children, reducing the need for liver transplantation.

In research published in the journal Nature Medicine, the researchers grew 3D cellular structure which, once transplanted into mice, developed into normal, functioning bile ducts.

Bile ducts are long, tube-like structures that carry bile, which is secreted by the liver and is essential for helping us digest food. If the ducts do not work correctly, for example in the childhood disease biliary atresia, this can lead to damaging build of bile in the liver.

The study suggests that it will be feasible to generate and transplant artificial human bile ducts using a combination of cell transplantation and tissue engineering technology. This approach provides hope for the future treatment of diseases of the bile duct; at present, the only option is a liver transplant.

The University of Cambridge research team, led by Professor Ludovic Vallier and Dr Fotios Sampaziotis from the Wellcome-MRC Cambridge Stem Cell Institute and Dr Kourosh Saeb-Parsy from the Department of Surgery, extracted healthy cells (cholangiocytes) from bile ducts and grew these into functioning 3D duct structures known as biliary organoids. When transplanted into mice, the biliary organoids assembled into intricate tubular structures, resembling bile ducts.

The researchers, in collaboration with Mr Alex Justin and Dr Athina Markaki from the Department of Engineering, then investigated whether the biliary organoids could be grown on a ‘biodegradable collagen scaffold’, which could be shaped into a tube and used to repair damaged bile ducts in the body. After four weeks, the cells had fully covered the miniature scaffolding resulting in artificial tubes which exhibited key features of a normal, functioning bile duct. These artificial ducts were then used to replace damaged bile ducts in mice. The artificial duct transplants were successful, with the animals surviving without further complications.

“Our work has the potential to transform the treatment of bile duct disorders,” explains Professor Vallier. “At the moment, our only option is liver transplantation, so we are limited by the availability of healthy organs for transplantation. In future, we believe it will be possible to generate large quantities of bioengineered tissue that could replace diseased bile ducts and provide a powerful new therapeutic option without this reliance on organ transplants.”

“This demonstrates the power of tissue engineering and regenerative medicine,” adds Dr Sampaziotis. “These artificial bile ducts will not only be useful for transplanting, but could also be used to model other diseases of the bile duct and potentially develop and test new drug treatments.”

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Materials provided by University of Cambridge. The original story is licensed under a Creative Commons License. Note: Content may be edited for style and length.

Health24.com | New microscope may help remove complete breast tumour

Up to 40% of women with breast cancer must undergo repeat procedures to remove cancerous cells that were missed during the first operation. This is due to a lack of  three-dimensional data.

But now a team of mechanical engineers and pathologists have invented a microscope that could potentially assist surgeons to remove breast tumours completely.

The microscope, developed by scientists and engineers at the University of Washington

Health24 previously reported that in some women with breast cancer, taking soy protein supplements boosted the expression of tumour genes associated with an increase in tumour cells.

When removing a breast tumour, known as a lumpectomy, surgeons attempt to remove the cancer but spare as much healthy tissue as possible. But it may take several days after surgery before lab results reveal if the lumpectomy was successful or if additional surgery is needed to remove cancerous cells that were missed, the study’s authors explained.

Part of the tumour left behind

“Surgeons are sort of flying blind during these breast-conserving surgeries. Oftentimes they’ve left some tumour behind which they don’t know about until a few days later when the pathologist finds it,” said mechanical engineering professor Jonathan Liu in a university news release.

“If we can rapidly image the entire surface or margin of the excised tissue during the procedure, we can tell them if they still have tumour left in the body or not. And that would be a huge benefit to cancer patients.”

The newly designed microscope uses a sheet of light to visually “slice” through and image a tissue sample without destroying any of it. This ensures all the tissue is preserved for further testing, which can help doctors learn more about the cancer and determine the best course of treatment, according to the study published in the journal Nature Biomedical Engineering.

Microscopic precision

“If we can do this without consuming any tissue, so much the better,” said co-author Dr Larry True, a professor of pathology at UW Medicine. “We want to use that valuable tissue for purposes which are becoming ever more important for treating patients such as sequencing the tumour cells and finding genetic abnormalities that we can target with specific drugs and other precision medicine techniques.”

“The tools we use in pathology have changed little over the past century,” said study co-author Dr Nicholas Reder, chief resident and clinical research fellow in UW Medicine’s Department of Pathology in the news release.

“This light-sheet microscope represents a major advance for pathology and cancer patients, allowing us to examine tissue in minutes rather than days and to view it in three dimensions instead of two, which will ultimately lead to improved clinical care.”

Read more:

Pituitary cancer

Allergies lower brain tumour risk

Cancer therapy named breakthrough of the year

Health24.com | Tattoo remorse? How to erase your ink

Perhaps your neon forearm tattoo with the name of your high school girlfriend wasn’t your brightest move ever.

If so, you’re not alone.

Forever is apparently in the eye of the beholder. One in eight tattooed Americans regrets getting what is supposed to be a permanent form of creative expression, according to a 2012 Harris Interactive survey. There are no statistics to indicate how many South Africans have tattoos.

Severe complications

According to a previous Health24 article there are other reasons for regretting getting that tattoo. One example is getting infected by contaminated tattoo inks and/or having bad reactions to the inks. 

Only trained people should do tattoos. The skin could be damaged, scarred or the wounds can become infected if someone who is not trained in that field, does the tattoo. Severe complications can arise if the instruments that are used are not disposable or are poorly sterilised, or the venue is unhygienic.

The American Society for Dermatologic Surgery reports that more and more people are doing something about removing that unwanted tattoo.

In 2011, its doctors performed nearly 100 000 tattoo removals, up from 86 000 in 2010. And the number continues to rise.

But before you embark on a tattoo cleanse, learn about your options. The US Food and Drug Administration (FDA), which regulates tattooing and tattoo removal, has some practical advice.

High-intensity laser energy

One way to go is professionally supervised laser removal, according to Mehmet Kosoglu, an FDA engineer.

The process exposes a tattoo to pulses of high-intensity laser energy. After exposure, tattoo pigment breaks up into small pieces, which can then be naturally metabolized by the body or excreted.

Some colours respond better to laser removal better than others, Kosoglu warns. Green, red and yellow are more stubborn than black and blue. And it will likely take six to 10 procedures to get the ink-free outcome you want.

Dermabrasion is another option, in which the top layer of skin is literally sanded away.

Or you can even have the tattooed skin cut away and surrounding skin stitched together.

Unexpected reactions

Be aware that there are no FDA-approved creams for tattoo removal, FDA dermatologist Dr Markham Luke said.

“FDA has not reviewed them, and is not aware of any clinical evidence that they work,” Luke noted in an agency news release. In fact, he said, ointments and creams marketed for tattoo removal may cause unexpected reactions, including rashes, burning, scarring or changes in skin pigmentation.

“If you have any concerns about having a tattoo removed, it’s a good idea to consult your dermatologist, who is knowledgeable about laser treatments,” Luke added.

Read more:

Why people get tattoos

The risks of tattoos

Tattoos the new vaccines?