Tag Archives: University of Granada

Good for your bones and good for art conservation: calcium

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The statues on Easter Island, the Great Wall of China, Egyptian pyramids, MesoAmerican pyramids, castles in Europe and other structures made of stone are deteriorating and now comes another approach to halting the destruction. (I have covered other approaches to the problem in two previous postings, a December 5, 2017 posting, Europe’s cathedrals get a ‘lift’ with nanoparticles, and an October 21, 2014 posting, Heart of stone.)

An August 7, 2019 news item on ScienceDaily announces the latest in conserving stone monuments and structures,

When it comes to cultural heritage sites, there are few things historians wouldn’t do to preserve them for future generations. In particular, stone buildings and sculptures made of plaster and marble are increasingly at risk of damage from air pollution, acid rain and other factors. Researchers now report a new, calcium-based conservation treatment inspired by nature that overcomes many drawbacks of currently used methods.

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An August 7, 2019 American Chemical Society (ACS) news release, which originated the news item, provides a bit more technical detail,

Historically, conservation scientists have turned to alkoxysilanes, silicon-based molecules used to consolidate stone and other artworks, in their preservation efforts. However, alkoxysilane treatments do not bond properly with non-silicate surfaces, are prone to cracking and are limited in their ability to repel water. Adding other compounds to this treatment have helped overcome these effects, but only to a point. Instead Encarnación Ruiz Agudo and colleagues looked to nature for inspiration, and found that calcium could be the answer. As a major element of strong, natural structures like bone and kidney stones, the researchers theorized that nanoparticles made from calcium could bolster alkoxysilanes and provide the desired protective effects to conserve historical artifacts.

The researchers made calcium carbonate and calcium oxalate nanoparticles and included polydimethylsiloxane (PDMS) as a stabilizer. PDMS also likely helps the nanoparticles bond to surfaces. The team added the nanoparticles to traditional alkoxysilane treatments, then applied them to samples of three different building materials: white marble, calcarenite limestone and gypsum plaster, and put the samples through a battery of tests. Overall, the results showed enhanced hydrophobicity, less cracking and improved surface adhesion compared to alkoxysilane treatments alone, with calcium oxalate providing a marked improvement in acid resistance. A minimal color effect was observed, but the researchers say this change was within acceptable values for conservation efforts.

The authors acknowledge funding from the European Regional Development Fund, the Regional Government of Andalusia, the Spanish Ministry of Economy and Finance and the University of Granada.

Here’s a link to and a citation for the paper,

Bioinspired Alkoxysilane Conservation Treatments for Building Materials Based on Amorphous Calcium Carbonate and Oxalate Nanoparticles by A. Burgos-Cara, C. Rodríguez-Navarro, M. Ortega-Huertas, E. Ruiz-Agudo. ACS Appl. Nano Mater.2019XXXXXXXXXX-XXX DOI: https://doi.org/10.1021/acsanm.9b00905 Publication Date:July 18, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Real-time tracking of UV (ultraviolet light) exposure for all skin types (light to dark)

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It’s nice to find this research after my August 21, 2018 posting where I highlighted (scroll down to ‘Final comments’) the issues around databases and skin cancer data which is usually derived from fair-skinned people while people with darker hues tend not to be included. This is partly due to the fact that fair-skinned people have a higher risk and also partly due to myths about how more melanin in your skin somehow protects you from skin cancer.

This October 4, 2018 news item on ScienceDaily announces research into a way to track UV exposure for all skin types,

Researchers from the University of Granada [Spain] and RMIT University in Melbourne [Australia] have developed personalised and low-cost wearable ultraviolet (UV) sensors that warn users when their exposure to the sun has become dangerous.

The paper-based sensor, which can be worn as a wristband, features happy and sad emoticon faces — drawn in an invisible UV-sensitive ink — that successively light up as you reach 25%, 50%, 75% and finally 100% of your daily recommended UV exposure.

The research team have also created six versions of the colour-changing wristbands, each of which is personalised for a specific skin tone  [emphasis mine]– an important characteristic given that darker people need more sun exposure to produce vitamin D, which is essential for healthy bones, teeth and muscles.

An October 2, 2018 University of Granada press release (also on EurekAlert) delves further,

Four of the wristbands, each of which indicates a different stage of exposure to UV radiation (25%, 50%, 75% and 100%)

The emoticon faces on the wristband successively “light up” as exposure to UV radiation increases

Skin cancer, one of the most common types of cancer throughout the world, is primarily caused by overexposure to ultraviolet radiation (UVR). In Spain, over 74,000 people are diagnosed with non-melanoma skin cancer every year, while a further 4,000 are diagnosed with melanoma skin cancer. In regions such as Australia, where the ozone layer has been substantially depleted, it is estimated that approximately 2 in 3 people will be diagnosed with skin cancer by the time they reach the age of 70.

“UVB and UVC radiation is retained by the ozone layer. This sensor is especially important in the current context, given that the hole in the ozone layer is exposing us to such dangerous radiation”, explains José Manuel Domínguez Vera, a researcher at the University of Granada’s Department of Inorganic Chemistry and the main author of the paper.

Domínguez Vera also highlights that other sensors currently available on the market only measure overall UV radiation, without distinguishing between UVA, UVB and UVC, each of which has a significantly different impact on human health.  In contrast, the new paper-based sensor can differentiate between UVA, UVB and UVC radiation. Prolonged exposure to UVA radiation is associated with skin ageing and wrinkling, while excessive exposure to UVB causes sunburn and increases the likelihood of skin cancer and eye damage.

Drawbacks of the traditional UV index

Ultraviolet radiation is determined by aspects such as location, time of day, pollution levels, astronomical factors, weather conditions such as clouds, and can be heightened by reflective surfaces like bodies of water, sand and snow. But UV rays are not visible to the human eye (even if it is cloudy UV radiation can be high) and until now the only way of monitoring UV intensity has been to use the UV index, which is standardly given in weather reports and indicates 5 degrees of radiation;  low, moderate, high, very high or extreme.

Despite its usefulness, the UV index is a relatively limited tool. For instance, it does not clearly indicate what time of the day or for how long you should be outside to get your essential vitamin D dose, or when to cover up to avoid sunburn and a heightened risk of skin cancer.

Moreover, the UV index is normally based on calculations for fair skin, making it unsuitable for ethnically diverse populations.  While individuals with fairer skin are more susceptible to UV damage, those with darker skin require much longer periods in the sun in order to absorb healthy amounts of vitamin D. In this regard, the UV index is not an accurate tool for gauging and monitoring an individual’s recommended daily exposure.

UV-sensitive ink

The research team set out to tackle the drawbacks of the traditional UV index by developing an inexpensive, disposable and personalised sensor that allows the wearer to track their UV exposure in real-time. The sensor paper they created features a special ink, containing phosphomolybdic acid (PMA), which turns from colourless to blue when exposed to UV radiation. They can use the initially-invisible ink to draw faces—or any other design—on paper and other surfaces. Depending on the type and intensity of the UV radiation to which the ink is exposed, the paper begins to turn blue; the greater the exposure to UV radiation, the faster the paper turns blue.

Additionally, by tweaking the ink composition and the sensor design, the team were able to make the ink change colour faster or slower, allowing them to produce different sensors that are tailored to the six different types of skin colour. [emphasis mine]

Applications beyond health

This low-cost, paper-based sensor technology will not only help people of all colours to strike an optimum balance between absorbing enough vitamin D and avoiding sun damage — it also has significant applications for the agricultural and industrial sectors. UV rays affect the growth of crops and the shelf life of a range of consumer products. As the UV sensors can detect even the slightest doses of UV radiation, as well as the most extreme, this new technology could have vast potential for industries and companies seeking to evaluate the prolonged impact of UV exposure on products that are cultivated or kept outdoors.

The research project is the result of fruitful collaborations between two members of the UGR BIONanoMet (FQM368) research group; Ana González and José Manuel Domínguez-Vera, and the research group led by Dr. Vipul Bansal at RMIT University in Melbourne (Australia).

Here’s a link to and a citation for the paper,

Skin color-specific and spectrally-selective naked-eye dosimetry of UVA, B and C radiations by Wenyue Zou, Ana González, Deshetti Jampaiah, Rajesh Ramanathan, Mohammad Taha, Sumeet Walia, Sharath Sriram, Madhu Bhaskaran, José M. Dominguez-Vera, & Vipul Bansal. Nature Communicationsvolume 9, Article number: 3743 (2018) DOI: https://doi.org/10.1038/s41467-018-06273-3 Published 25 September 2018

This paper is open access.

The Leonardo Project and the master’s DNA (deoxyribonucleic acid)

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I’ve never really understood the mania for digging up bodies of famous people in history and trying to ascertain how the person really died or what kind of diseases they may have had but the practice fascinates me. The latest famous person to be subjected to a forensic inquiry centuries after death is Leonardo da Vinci. A May 5, 2016 Human Evolution (journal) news release on EurekAlert provides details,

A team of eminent specialists from a variety of academic disciplines has coalesced around a goal of creating new insight into the life and genius of Leonardo da Vinci by means of authoritative new research and modern detective technologies, including DNA science.

The Leonardo Project is in pursuit of several possible physical connections to Leonardo, beaming radar, for example, at an ancient Italian church floor to help corroborate extensive research to pinpoint the likely location of the tomb of his father and other relatives. A collaborating scholar also recently announced the successful tracing of several likely DNA relatives of Leonardo living today in Italy (see endnotes).

If granted the necessary approvals, the Project will compare DNA from Leonardo’s relatives past and present with physical remnants — hair, bones, fingerprints and skin cells — associated with the Renaissance figure whose life marked the rebirth of Western civilization.

The Project’s objectives, motives, methods, and work to date are detailed in a special issue of the journal Human Evolution, published coincident with a meeting of the group hosted in Florence this week under the patronage of Eugenio Giani, President of the Tuscan Regional Council (Consiglio Regionale della Toscana).

The news release goes on to provide some context for the work,

Born in Vinci, Italy, Leonardo died in 1519, age 67, and was buried in Amboise, southwest of Paris. His creative imagination foresaw and described innovations hundreds of years before their invention, such as the helicopter and armored tank. His artistic legacy includes the iconic Mona Lisa and The Last Supper.

The idea behind the Project, founded in 2014, has inspired and united anthropologists, art historians, genealogists, microbiologists, and other experts from leading universities and institutes in France, Italy, Spain, Canada and the USA, including specialists from the J. Craig Venter Institute of California, which pioneered the sequencing of the human genome.

The work underway resembles in complexity recent projects such as the successful search for the tomb of historic author Miguel de Cervantes and, in March 2015, the identification of England’s King Richard III from remains exhumed from beneath a UK parking lot, fittingly re-interred 500 years after his death.

Like Richard, Leonardo was born in 1452, and was buried in a setting that underwent changes in subsequent years such that the exact location of the grave was lost.

If DNA and other analyses yield a definitive identification, conventional and computerized techniques might reconstruct the face of Leonardo from models of the skull.”

In addition to Leonardo’s physical appearance, information potentially revealed from the work includes his ancestry and additional insight into his diet, state of health, personal habits, and places of residence.

According to the news release, the researchers have an agenda that goes beyond facial reconstruction and clues about  ancestry and diet,

Beyond those questions, and the verification of Leonardo’s “presumed remains” in the chapel of Saint-Hubert at the Château d’Amboise, the Project aims to develop a genetic profile extensive enough to understand better his abilities and visual acuity, which could provide insights into other individuals with remarkable qualities.

It may also make a lasting contribution to the art world, within which forgery is a multi-billion dollar industry, by advancing a technique for extracting and sequencing DNA from other centuries-old works of art, and associated methods of attribution.

Says Jesse Ausubel, Vice Chairman of the Richard Lounsbery Foundation, sponsor of the Project’s meetings in 2015 and 2016: “I think everyone in the group believes that Leonardo, who devoted himself to advancing art and science, who delighted in puzzles, and whose diverse talents and insights continue to enrich society five centuries after his passing, would welcome the initiative of this team — indeed would likely wish to lead it were he alive today.”

The researchers aim to have the work complete by 2019,

In the journal, group members underline the highly conservative, precautionary approach required at every phase of the Project, which they aim to conclude in 2019 to mark the 500th anniversary of Leonardo’s death.

For example, one objective is to verify whether fingerprints on Leonardo’s paintings, drawings, and notebooks can yield DNA consistent with that extracted from identified remains.

Early last year, Project collaborators from the International Institute for Humankind Studies in Florence opened discussions with the laboratory in that city where Leonardo’s Adoration of the Magi has been undergoing restoration for nearly two years, to explore the possibility of analyzing dust from the painting for possible DNA traces. A crucial question is whether traces of DNA remain or whether restoration measures and the passage of time have obliterated all evidence of Leonardo’s touch.

In preparation for such analysis, a team from the J. Craig Venter Institute and the University of Florence is examining privately owned paintings believed to be of comparable age to develop and calibrate techniques for DNA extraction and analysis. At this year’s meeting in Florence, the researchers also described a pioneering effort to analyze the microbiome of a painting thought to be about five centuries old.

If human DNA can one day be obtained from Leonardo’s work and sequenced, the genetic material could then be compared with genetic information from skeletal or other remains that may be exhumed in the future.

Here’s a list of the participating organizations (from the news release),

  • The Institut de Paléontologie Humaine, Paris
  • The International Institute for Humankind Studies, Florence
  • The Laboratory of Molecular Anthropology and Paleogenetics, Biology Department, University of Florence
  • Museo Ideale Leonardo da Vinci, in Vinci, Italy
  • J. Craig Venter Institute, La Jolla, California
  • Laboratory of Genetic Identification, University of Granada, Spain
  • The Rockefeller University, New York City

You can find the special issue of Human Evolution (HE Vol. 31, 2016 no. 3) here. The introductory essay is open access but the other articles are behind a paywall.