Thursday, December 12, 2024

‘Forever’ chemicals

 ‘Forever’ chemicals can be destroyed with clever chemistry- now test these techniques outside the lab



A simple chemical bond between carbon and fluorine atoms changed the world - for the better, and then for the worse.

Such bonds lie at the heart of per- and polyfluoroalkyl substances (PFAS), a group of compounds, numbering in the millions, that are remarkably water-, heat- and greaseproof. Discovered in the 1930s with the advent of polytetrafluoroethylene (PTFE, branded as Teflon), these chemicals make pans non-stick and keep the rain off our jackets. Varieties of cosmetics, fire-retardant foam, kitchen utensils, metal coatings, packaging, textiles and more all contain them.

But they have become known as ‘forever chemicals’ because they are difficult to break down, persisting in the environment for perhaps 1,000 years or more. They are also ‘everywhere’ chemicals, in that they can be found in rivers and on the tops of mountains. This would not be such a problem, except that the chemicals are highly toxic, having been linked to developmental problems and conditions ranging from cancer to immune-system suppression.

The world is belatedly starting to act, both to stop forever chemicals entering the environment and to clean up those already there. But more action is needed  and faster.

The carbon–fluorine (C–F) bond is one of the strongest in organic chemistry, requiring huge amounts of energy to break down, at huge expense. But now two papers in Nature1,2 describe two low-energy ways to overcome the C–F bond.

Both methods combine a catalyst with some relatively simple chemistry driven by the energy of visible light. In each case, the catalyst absorbs light that then triggers a reaction.

Chemist Garret Miyake at Colorado State University in Fort Collins and his colleagues use this absorbed energy to reduce the C–F bond to carbon–hydrogen — albeit not in Teflon1. Yan-Biao Kang, a chemist at the University of Science and Technology of China in Hefei, and his colleagues uses this energy to break the bond and the overall molecule down to smaller constituent parts2, in temperatures as low as 40 °C. Both papers, without doubt, mark a major step forward.

Important next steps include using these ideas in real-world settings, for example to develop catalysts that work in waste water or that can be used to clean up PFAS in contaminated soils. If a method can be adapted so that it is powered by sunlight, that would be of huge benefit.

Update regulations

Any solutions that emerge from such developments will address only part of the problem. There’s an urgent need both for updated regulation of chemicals, and for more research into safer alternatives to PFAS that do the same things without harming human health and the environment.

On the regulatory front, scientists advising the European Chemicals Agency are considering a proposal from countries including Germany and the Netherlands to ban 10,000 PFAS substances currently in everyday use.

At the global level, the Stockholm Convention, an international agreement that bans persistent organic pollutants, is revisiting its latest list which classifies only three types of PFAS as banned substances.

It is equally important to stop PFAS entering the water supply. In 2021, the European Environment Agency (working under the European Union’s Drinking Water Directive) for the first time set upper limits on PFAS levels in water. In the United States, the Environmental Protection Agency has gone further. In April, it set safe limits for drinking water, under which there will be ‘close to zero’ levels of certain PFAS.

The European proposal doesn’t yet extend to banning PFAS in applications such as medicine or transport, for the simple reason that these chemicals are still too useful and adequate alternatives are yet to be found. C–F bonds in pharmaceuticals allow molecules to remain stable, which is necessary for products’ shelf life.

Medicinal chemists are trying to make drug molecules that contain C–F bonds but can biodegrade safely once they leave the body. In some circumstances, PFAS have replaced other harmful chemicals — for example, outdated, ozone-destroying chlorofluorocarbon (CFC) refrigerants. Non-fluorinated refrigerants are also available, including ammonia and carbon dioxide, but large-scale roll out will need regulatory input.

A lot of clever chemistry, together with updated regulation, will be needed to ensure that forever chemicals finally become never chemicals.

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Tuesday, December 10, 2024

New method detects unrecognized chemicals in the human body

 New method detects unrecognized chemicals in the human body

From the 1960s to the 1980s, the use of lead in fuel, paints, and pipes caused widespread contamination. It is estimated that 170 million Americans alive today were exposed to high lead levels as children, which caused significant harm, including a measurable drop in IQ scores. While we now understand the dangers of these chemicals, large sections of the population are still exposed to them. UNICEF reports that about 800 million children globally, nearly half of whom live in South Asia, are still exposed to unsafe levels of lead resulting from the hazardous recycling of lead-acid batteries.

Much like the hidden dangers of lead in the past, many of the chemicals we are exposed to today remain poorly understood, along with their potential long-term health effects. To address this issue, researchers at Chiba University in Japan have recently developed an innovative method to detect unrecognized foreign chemicals in the human body. The study was made available online on 26 October 2024 and was published in Volume 286 of the journal Ecotoxicology and Environmental Safety on 1 November 2024. Led by adjunct researcher Dr. Akifumi Eguchi, the study included contributions from Dr. Chisato Mori, Dr. Kenichi Sakurai, and Dr. Midori Yamamoto from the Center for Preventive Medical Sciences at Chiba University.

Non-targeted chemical analysis poses significant challenges owing to the large volume of data involved. Additionally, since chemicals exist in various forms, it is necessary to distinguish between endogenous (those naturally produced by the body) and exogenous (those derived from external sources like air, water, or food) chemicals. To address this, the proposed method uses advanced statistical techniques, including Principal Component Analysis, regularized Generalized Canonical Correlation Analysis, Uniform Manifold Approximation and Projection, and OPTICS clustering. These approaches reduce data complexity and help reveal patterns and groupings among the chemical compounds present in the samples, providing deeper insights into their origins and potential impacts.

Using this method, the researchers analyzed serum samples from 84 pregnant women at 32 weeks of pregnancy. These samples were then examined using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry. The detected chemicals were classified based on their origin using the PubChemLite for Exposomics database, which contains information on over 371,663 chemicals. Endogenous chemicals were identified as those naturally produced by the body and associated with biological pathways, while exogenous chemicals were categorized as substances introduced from external sources such as the environment, diet, or lifestyle.

The researchers identified 106 compounds, of which 51 were endogenous and 55 were exogenous. Most of the exogenous chemicals were found to have been introduced into the body through dietary sources. Additionally, they found compounds associated with possible health risks, such as phthalates, nitrogenous compounds, and parabens. Moreover, some of the chemicals identified were found to impact biological pathways, such as amino acid metabolism, protein and mineral transport, and energy metabolism.

While these findings show a link between chemical exposure and its effects on the body, the researchers emphasize that they do not establish a direct cause-and-effect relationship. Since most of the exogenous chemicals were linked to dietary sources, it remains unclear whether the changes in metabolites are due to the substances themselves or the diet. Despite these limitations, the study offers a new method for identifying chemicals and evaluating their potential effects on human health.

"These findings can contribute to public health improvement through the implementation of chemical regulations and related protective measures," says Dr. Eguchi. Just as the realization of dangers associated with lead and asbestos led to significant reform and restrictions on these chemicals, the results of this study could help identify new potentially harmful chemicals, paving the way for better regulations to protect human health.

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Monday, December 9, 2024

Safe storage and use of chemicals in hot weather

 

Safe storage and use of chemicals in hot weather


As summer approaches and temperatures (hopefully) rise, storing laboratory chemicals safely can become more challenging. This article has some simple steps you can take to ensure that your chemicals are stored safely during hot weather.



Keep your chemicals cool

Every chemical purchase should come with a Safety Data Sheet (SDS) from the supplier. This document details critical information for safe handling and storage, including fire safety measures, potential chemical reactions, and – crucially for temperature control – the maximum recommended storage temperature for the chemical.

Maintaining proper temperature for chemicals

To ensure safety, liquid chemicals must be stored below their boiling point, while solid chemicals need to be kept below their sublimation* temperature (the point where they transition directly from solid to gas). Here are some practical steps to achieve this:

  • Minimise sun exposure: Direct sunlight can significantly raise the temperature. Consider storing chemicals in shaded areas
  • Utilise insulated storage: Insulated cabinets, rooms or refrigerators can help maintain a consistent cool temperature.
  • Control airflow: Strategically placed ventilation systems can circulate cool air and remove hot air, preventing excessive temperature build-up.

By following these measures, you can create a safe and controlled environment for storing your chemicals.

* Sublimation is the conversion of a substance from a solid to a gaseous state without becoming a liquid. A good example of this is the evaporation of dry ice (frozen carbon dioxide) directly to carbon dioxide gas, without producing a liquid during the process. 

If chemicals are stored outside, they must

  • Not be classified as a flammable liquid (category 1, 2, or 3).
  • Not be stored in air-tight containers, as this may introduce a risk of explosion when heated.
  • Be stored away from sources of ignition (including direct sunlight).

When these conditions cannot be met, the department may consider temporarily relocating their chemicals inside, following a suitable and sufficient risk assessment and supporting control measures.

Don’t forget that areas of shade change as the day progresses, make sure that your chemicals are in shade throughout the day. 

Ensure that your chemical store has good ventilation

Good ventilation ensures that any gases released by chemicals as they heat up do not create an explosive atmosphere risk. Where possible, mechanical ventilation should be used (e.g. local exhaust ventilation – LEV). 

Regularly check your chemical stores

Check your chemicals reguarly. Are containers bulging, have lids popped off, have containers burst? If so, urgent action will need to be taken to ensure that the remaining chemicals do not pose a risk of fire or explosion. 

Don’t forget your chemical waste!

Chemical wastes, and mixtures of chemical wastes, are also susceptible to high temperatures. The above measures should also be considered for your chemical wastes.

Compressed gas cylinders

Compressed gas cylinders are categorised as inert, oxidising, flammable, and toxic. Regardless of the contents of the cylinders, they should be protected from heat and kept away from flammable materials. Under extremes of temperature, the pressure inside the cylinder may cause the cylinder to rupture and cause an explosion. 

Criteria for flammable liquids

  • Category 1 – flashpoint of less than 23°C and an initial boiling point of less than or equal to 35°C.
  • Category 2 – flashpoint of less than 23°C and an initial boiling point of over 35°C.
  • Category 3 – flashpoint of greater than or equal to 23°C and less than or equal to 60°C

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Friday, December 6, 2024

Graphene

 Graphene

What is Graphene?

Graphene is a single layer of carbon atoms tightly packed into a two-dimensional honeycomb lattice. Discovered in 2004, it has become a groundbreaking material in science and technology due to its exceptional properties. Often called the "wonder material," graphene is ultra-thin yet incredibly strong, lightweight, and highly conductive, making it suitable for a wide range of applications.



Properties of Graphene

Mechanical Strength

Graphene is remarkably strong, with a tensile strength about 200 times greater than steel while being extremely lightweight. It is also flexible, allowing it to bend without breaking, making it ideal for applications requiring durability and elasticity.

Electrical Conductivity

Graphene  is an excellent conductor of electricity, enabling electrons to move rapidly across its surface. This high conductivity, combined with its zero bandgap, makes it a promising material for advanced electronic devices and transistors.

Thermal Conductivity

With thermal conductivity surpassing that of most materials, graphene efficiently dissipates heat. This property is crucial for applications in thermal management in electronics.

Optical Properties

Graphene absorbs only 2.3% of visible light, making it nearly transparent. This unique optical characteristic is valuable in optoelectronic devices such as touchscreens and solar cells.

Impermeability

Graphene acts as an impenetrable barrier, even to the smallest atoms like helium. This makes it ideal for creating protective coatings and filtration membranes.

Chemical Properties

Graphene is chemically stable and can be easily functionalized to enhance its reactivity for specific applications, such as drug delivery or sensors.

Applications of Graphene

Electronics and Semiconductors

Graphene's high electrical conductivity and flexibility make it a game-changer for electronics. It is used in advanced transistors, flexible electronic devices, and supercapacitors, improving efficiency and performance.

Energy Storage

In batteries, graphene enhances charge times, energy density, and lifespan. It is used in lithium-ion and sodium-ion batteries, as well as in fuel cells for efficient energy conversion.

Composites and Coatings

Graphene strengthens materials when added to polymers or metals, making them lighter and more durable. It is also used in anti-corrosion coatings, protecting surfaces from rust and degradation.

Medical Applications

Functionalized graphene is revolutionizing medicine, enabling targeted drug delivery, biosensors for disease detection, and scaffolds for tissue engineering. Its biocompatibility adds to its versatility in healthcare.

Environmental Applications

Graphene is instrumental in water purification, offering effective desalination and contaminant filtration. It is also used to absorb pollutants from air and water, contributing to cleaner environments.

Thermal Management

Due to its exceptional heat dissipation, graphene is ideal for managing heat in high-performance electronics, extending the life of devices.

Optoelectronics

Graphene’s optical properties are utilized in transparent conductive films, photodetectors, and light-emitting devices, paving the way for advanced display technologies.

Sensors

Graphene’s sensitivity to environmental changes makes it an excellent material for gas sensors, chemical detectors, and pressure sensors, enabling precise and reliable measurements.

Future Potential

Graphene holds immense potential for next-generation technologies such as quantum computing, advanced robotics, and space exploration. Its unique combination of properties continues to inspire innovation, making it a cornerstone material for the future of engineering and science.

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 Graphene experiment proves patterns in chaos in quantum realm

Researchers from the University of California, Harvard University, University of Manchester, UC Santa Cruz and the National Institute for Materials Science in Tsukuba, Japan have conducted an experiment that confirms a 40 year old theory that electrons confined in quantum space would move along common paths rather than producing a chaotic array of trajectories.


Electrons exhibit both particle and wave-like properties and behave in ways that are often counterintuitive, and under certain conditions, their waves can interfere with each other in a way that concentrates their movement into certain patterns. Physicists call these common paths “unique closed orbits.”

Physicist Jairo Velasco, Jr. achieved this in his lab using an intricate combination of advanced imaging techniques and precise control over electrons behavior within graphene, whose unique properties and two-dimensional structure make it ideal for observing quantum effects. In their experiment, Velasco’s team utilized the finely tipped probe of a scanning tunneling microscope to first create a trap for electrons, and then hover close to a graphene surface to detect electrons movements without physically disturbing them.

The benefit of electrons following closed orbits within a confined space is that the subatomic particle’s property would be better preserved as it moves from one point to another, according to Velasco. He said this has vast implications for everyday electronics, explaining how information encoded in an electron’s properties could be transferred without loss, conceivably resulting in lower-power, highly efficient transistors. “One of the most promising aspects of this discovery is its potential use in information processing,” Velasco said. “By slightly disturbing, or ‘nudging’ these orbits, electrons could travel predictably across a device, carrying information from one end to the other.”

In physics, these unique electron sorbits are known as “quantum scars.” This was first explained in a 1984 theoretical study by Harvard University physicist Eric Heller, who used computer simulations to reveal that confined electrons would move along high-density orbits if reinforced by their wave motions interfering with each other. 

“Quantum scarring is not a curiosity. But rather, it is a window onto the strange quantum world,” said Heller, also a co-author on the paper. “Scarring is a localization around orbits that come back on themselves. These returns have no long-term consequence in our normal classical world—they are soon forgotten. But they are remembered forever in the quantum world.”

With Heller’s theory proven, researchers now have the empirical foundation needed to explore potential applications. Today’s transistors, already at the nanoelectronic scale, could become even more efficient by incorporating quantum scar-based designs, enhancing devices like computers, smartphones, and tablets, which rely on densely packed transistors to boost processing power. “For future studies, we plan to build on our visualization of quantum scars to develop methods to harness and manipulate scar states,” Velasco said. “The harnessing of chaotic quantum phenomena could enable novel methods for selective and flexible delivery of electrons at the nanoscale—thus, innovating new modes of quantum control.”

Velasco’s team used a visual model often referred to as a "billiard" to illustrate the classical mechanics of linear versus chaotic systems. A billiard is a bounded area that reveals how particles inside move, and a common shape used in physics is called a “stadium,” where the ends are curved and the edges straight. In classical chaos, a particle would bounce around randomly and unpredictably—eventually covering the entire surface.

In this experiment, the team created a stadium billiard on atom-thin graphene that measured roughly 400 nanometers in length. Then, with the scanning tunneling microscope, they were able to observe quantum chaos in action: finally seeing with their own eyes the pattern of electron orbits within the stadium billiard they created in Velasco’s lab. “I am very excited we successfully imaged quantum scars in a real quantum system,” said first and co-corresponding author Zhehao Ge, a UC Santa Cruz graduate student at the time of this study’s completion. “Hopefully, these studies will help us gain a deeper understanding of chaotic quantum systems.”  

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Wednesday, December 4, 2024

 

Study discovers a nano-switch mechanism controlled by a single hydrogen atom in all living organisms



A group of researchers in Japan has revealed, for the first time, a mechanism for controlling the potential of an electron carrier protein in the redox reaction that all organisms need to obtain energy. The researchers report that the electric potential of the iron-sulfur cluster changes dramatically depending on the presence or absence of a single hydrogen atom on an amino acid side chain, a so-called "nano-switch" mechanism.

The results not only deepen the scientific understanding of biological reactions but also provide a major clue to the future development of ultra-sensitive sensors for oxygen and  and novel drugs. Most reactions in organisms involve electron transfer, which is called a . For example, respiration and photosynthesis can be classified as redox reactions. Some proteins that assist in electron transfer contain iron and sulfur.

Ferredoxin is a small protein that contains iron-sulfur clusters and is known as the electron carrier in living organisms. Ferredoxin is a universal protein that is thought to be present in almost all living organisms; however, the mechanism by which ferredoxin stably carries electrons has remained a mystery to date.

In the study, the researchers conducted experiments using the Ibaraki Biological Crystal Diffractometer (iBIX) at the Materials and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) and determined the precise three-dimensional structure of a ferredoxin at the hydrogen  in experiments using a neutron beam.

Visualizing hydrogen atoms in protein molecules using neutrons is extremely difficult, and less than 0.2% of the entire protein three-dimensional structure database has been reported. Theoretical calculations using experimental geometry including hydrogen atoms were performed to elucidate the electronic structure of the iron-sulfur cluster in the ferredoxin.

The researchers found that an amino acid residue (aspartic acid 64) located far from the iron-sulfur cluster has a significant effect on the probability of electron transfer in the iron-sulfur cluster, and plays a role like a switch that controls the  in ferredoxin. Furthermore, the study found that the mechanism is universal in organisms.

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Tuesday, December 3, 2024

Material Science

 

New Polymer Technology Visualizes Shockwaves, Offering Breakthroughs in Material Science




A team of researchers from the National Institute of Standards and Technology (NIST), University of Southern Mississippi, Arizona State University, Rensselaer Polytechnic Institute, and U.S. Army Corps of Engineers has developed an innovative polymer material capable of visualizing shockwaves during high-velocity impacts. This breakthrough enables scientists to better understand how materials absorb energy and respond to extreme conditions, which has wide-ranging implications for studies on brain trauma, advanced manufacturing, and space exploration.

The research published in Nature Communications, demonstrates how a polymer containing mechanophores—molecules that illuminate under large mechanical force—can visually record the response of the material to high-speed projectile impacts. Notably, the mechanophores captured subsurface distortions in the material, information that was previously impossible to access. By integrating molecular-level reactions with advanced imaging techniques, the researchers can now visualize the formation of Mach cones—acoustic waves that travel faster than the speed of sound in the material, akin to a sonic boom from a supersonic aircraft.

“Our polymer allows us to ‘see’ how energy moves through the material during an impact,” said Polette Centellas, a researcher from the Materials Science and Engineering Division at NIST. “This opens up new possibilities for designing materials that can better withstand extreme conditions, from spacecraft shielding to advanced protective gear.”

This work uncovers a previously underexplored energy dissipation mechanism in polymer: shockwave attenuation. Traditionally, energy absorption in materials was thought to occur mainly through plastic deformation—where materials bend or break. However, this study shows that shockwaves play a significant role in energy dissipation, especially at high impact velocities.  

This discovery promises to drive innovations in developing more durable and tougher materials for industries ranging from defense to healthcare, where managing high-strain-rate impacts is crucial.

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Fazli Karim | Sarhad University | Innovative Research Award | Pakistan

Innovative Research Award Fazli Karim is a researcher at Sarhad University of Science & Information Technology, Pakistan, with experti...