| Many historical buildings were built of limestone, such as Vienna’s St. Stephen’s Cathedral. Limestone is easy to work with, but does not withstand weathering well. It consists mainly of calcite minerals that are relatively weakly bound to each other, which is why parts of the stone keep crumbling away over the years, often requiring costly restoration and conservation treatments. | |
| However, it is possible to increase the resistance of the stone by treating it with special silicate nanoparticles. The method is already being used, but what exactly happens in the process and which nanoparticles are best suited for this purpose has been unclear until now. | |
| A research team from TU Wien and the University of Oslo has now been able to clarify exactly how this artificial hardening process takes place through elaborate experiments at the DESY synchrotron in Hamburg and with microscopic examinations in Vienna. That way, the team could determine which nanoparticles are best suited for this purpose. |
An aqueous suspension with nanoparticles |
|
| “We use a suspension, a liquid, in which the nanoparticles initially float around freely,” says Prof. Markus Valtiner from the Institute of Applied Physics at TU Wien. “When this suspension gets into the rock, then the aqueous part evaporates, the nanoparticles form stable bridges between the minerals and give the rock additional stability.” | |
| This method is already used in restoration technology, but until now it was not known exactly what physical processes take place. When the water evaporates, a very special kind of crystallisation occurs: Normally, a crystal is a regular arrangement of individual atoms. However, not only atoms, but also entire nanoparticles can arrange themselves in a regular structure – this is then referred to as a “colloidal crystal”. | |
| The silicate nanoparticles come together to form such colloidal crystals when they dry in the rock and thus jointly create new connections between the individual mineral surfaces. This increases the strength of the natural stone. | |
Measurements at the large-scale research facility DESY and in Vienna |
|
| To observe this crystallisation process in detail, the TU Wien research team used the DESY synchrotron facility in Hamburg. Extremely strong X-rays can be generated there, which can be used to analyse the crystallisation during the drying process. | |
| “This was very important to understand exactly what the strength of the bonds that form depends on,” says Joanna Dziadkowiec (University of Oslo and TU Wien), the first author of the publication in which the research results have now been presented (Langmuir, “Cohesion Gain Induced by Nanosilica Consolidants for Monumental Stone Restoration”). “We used nanoparticles of different sizes and concentrations and studied the crystallisation process with X-ray analyses.” It was shown that the size of the particles is decisive for optimal strength gain. | |
| To this end, the TU Vienna also measured the adhesive force created by the colloidal crystals. For this purpose, a special interference microscope was used, which is perfectly suited for measuring tiny forces between two surfaces. | |
Small particles, more force |
|
| “We were able to show: The smaller the nanoparticles, the more can they strengthen the cohesion between the grains of minerals,” says Joanna Dziadkowiec. “If you use smaller particles, more binding sites are created in the colloidal crystal between two grains of minerals, and with the number of particles involved, the force with which they hold the minerals together thus also increases.” | |
| How many particles are present in the emulsion is also important. “Depending on the particle concentration, the crystallisation process proceeds slightly differently, and this has an influence on how the colloidal crystals form in detail,” says Markus Valtiner. The new findings will now be used to make restoration work more durable and more targeted. |
News
Tiny Metal Nanodots Obliterate Cancer Cells While Largely Sparing Healthy Tissue
Scientists have developed tiny metal-oxide particles that push cancer cells past their stress limits while sparing healthy tissue. An international team led by RMIT University has developed tiny particles called nanodots, crafted from a metallic compound, [...]
Gold Nanoclusters Could Supercharge Quantum Computers
Researchers found that gold “super atoms” can behave like the atoms in top-tier quantum systems—only far easier to scale. These tiny clusters can be customized at the molecular level, offering a powerful, tunable foundation [...]
A single shot of HPV vaccine may be enough to fight cervical cancer, study finds
WASHINGTON -- A single HPV vaccination appears just as effective as two doses at preventing the viral infection that causes cervical cancer, researchers reported Wednesday. HPV, or human papillomavirus, is very common and spread [...]
New technique overcomes technological barrier in 3D brain imaging
Scientists at the Swiss Light Source SLS have succeeded in mapping a piece of brain tissue in 3D at unprecedented resolution using X-rays, non-destructively. The breakthrough overcomes a long-standing technological barrier that had limited [...]
Scientists Uncover Hidden Blood Pattern in Long COVID
Researchers found persistent microclot and NET structures in Long COVID blood that may explain long-lasting symptoms. Researchers examining Long COVID have identified a structural connection between circulating microclots and neutrophil extracellular traps (NETs). The [...]
This Cellular Trick Helps Cancer Spread, but Could Also Stop It
Groups of normal cbiells can sense far into their surroundings, helping explain cancer cell migration. Understanding this ability could lead to new ways to limit tumor spread. The tale of the princess and the [...]
New mRNA therapy targets drug-resistant pneumonia
Bacteria that multiply on surfaces are a major headache in health care when they gain a foothold on, for example, implants or in catheters. Researchers at Chalmers University of Technology in Sweden have found [...]
Current Heart Health Guidelines Are Failing To Catch a Deadly Genetic Killer
New research reveals that standard screening misses most people with a common inherited cholesterol disorder. A Mayo Clinic study reports that current genetic screening guidelines overlook most people who have familial hypercholesterolemia, an inherited disorder that [...]
Scientists Identify the Evolutionary “Purpose” of Consciousness
Summary: Researchers at Ruhr University Bochum explore why consciousness evolved and why different species developed it in distinct ways. By comparing humans with birds, they show that complex awareness may arise through different neural architectures yet [...]
Novel mRNA therapy curbs antibiotic-resistant infections in preclinical lung models
Researchers at the Icahn School of Medicine at Mount Sinai and collaborators have reported early success with a novel mRNA-based therapy designed to combat antibiotic-resistant bacteria. The findings, published in Nature Biotechnology, show that in [...]
New skin-permeable polymer delivers insulin without needles
A breakthrough zwitterionic polymer slips through the skin’s toughest barriers, carrying insulin deep into tissue and normalizing blood sugar, offering patients a painless alternative to daily injections. A recent study published in the journal Nature examines [...]
Multifunctional Nanogels: A Breakthrough in Antibacterial Strategies
Antibiotic resistance is a growing concern - from human health to crop survival. A new study successfully uses nanogels to target and almost entirely inhibit the bacteria P. Aeruginosa. Recently published in Angewandte Chemie, the study [...]
Nanoflowers rejuvenate old and damaged human cells by replacing their mitochondria
Biomedical researchers at Texas A&M University may have discovered a way to stop or even reverse the decline of cellular energy production—a finding that could have revolutionary effects across medicine. Dr. Akhilesh K. Gaharwar [...]
The Stunning New Push to Protect the Invisible 99% of Life
Scientists worldwide have joined forces to build the first-ever roadmap for conserving Earth’s vast invisible majority—microbes. Their new IUCN Specialist Group reframes conservation by elevating microbial life to the same urgency as plants and [...]
Scientists Find a Way to Help the Brain Clear Alzheimer’s Plaques Naturally
Scientists have discovered that the brain may have a built-in way to fight Alzheimer’s. By activating a protein called Sox9, researchers were able to switch on star-shaped brain cells known as astrocytes and turn them into [...]
Vision can be rebooted in adults with amblyopia, study suggests
Temporarily anesthetizing the retina briefly reverts the activity of the visual system to that observed in early development and enables growth of responses to the amblyopic eye, new research shows. In the common vision [...]
