Tag Archives: technology

Plastic replacements: some new conSQUIDerations

Posted on March 27, 2019 by | 3 comments

The amount of plastic that has been produced to date now exceeds 8300 million metric tonnes (Mt). To put this into perspective, the average blue whale weighs approximately 180 Mt, thus 46 million blue whale’s worth of plastic has been produced since humans started commercializing plastics in 1950. Our society had become extremely dependent on plastic products and synthetic (petroleum- based) textiles which cause serious consequences such as microplastic and microfiber pollution as I’ve discussed in previous blog posts.

Figure 1. Size reference for blue whales. Wikipedia Commons

Bioplastics have more recently taken the stage as a potential avenue for replacing petroleum-based plastics. Biologically based polymers have structural elements such as helices, β-turns, β-sheets and coils which provide structural integrity and resilience and can replicate the desirable polymeric interactions in plastics. Additionally, a lot of new material is being developed based on the protein polymers that are naturally occurring in biological systems (including ourselves).

Figure 2. Fibrous protein polymers have molecular architecture that can include (i) helices and coils, (ii) β-turns and β-spirals, and (iii) β-sheets. Source

Video 1. SRT- coated fabrics that self-heal in water.

Squid ring teeth (SRT) are an especially promising candidate for making functional fibres and films due to its strength, conductivity and self-healing properties. The SRT are located inside the suction cups of the tentacles of squids and are composed of a naturally occurring protein complex. Fortunately, it is not necessary to harvest squid to obtain the SRT proteins as they can be biosynthetically produced since having their genome sequenced. The SRT-inspired monomer is repeated to create a polymeric chain and the resulting protein that is produced is named accordingly as tandem repeat (TR) proteins.

Figure 3. The Squid ring teeth of a giant squid. Wikipedia Commons

Figure 4. Optical images of squid ring teeth (SRT) and the six common squid species they originate from. Source

Films produced with SRT proteins consist of disordered domains that provide elasticity and flexibility to the materials in addition to ordered domains such as β-sheets that provide mechanical strength. One study designed four TR proteins denoted as TR-nX where X was the number of repeat units within the molecule. They measured the mechanical force of these four TR proteins and found that the ultimate strength of the protein’s scale linearly, with TR-n25 reaching an ultimate strength of 40 MPa. As seen in Figure 4 below, there is a limitation of the study due to sample size. The error bars of the TR-n12 and TR-n25 overlap, so it is not possible to say there is a statistically significant difference from each other.

Figure 4. Mechanical testing of fully hydrated TR proteins (inset shows 1/n dependence) Source

Additionally, SRT protein films have been suggested as a potential solution to the issues related to the release of microfibers into the water from washing. A cloth made from polyester was coated with an SRT protein film and was found to dramatically increase the cloths resistance to abrasion (and microfiber release) compared to cloths that were not coated with SRT protein films.

While there is still a lot of further research to be done, SRT-based proteins are a promising avenue for making our world a little bit less plastic.

~Isla

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Photoactivated Self-healing Copolymers- It’s Lit

Posted on March 25, 2019 by | Leave a comment

A scratch on your car may no longer need a trip to the auto-shop. Simply applying heat or light could remedy this issue. This idea could soon be a reality using vitrimers, a new class of plastics that have thermal and chemical stability, but can also be self-healing on a small scale and fully recyclable on a larger scale.

Taylor Wright from Dr. Wolf’s group at UBC. Source

In 2018, at the University of British Columbia, Taylor Wright under the supervision of Dr. Michael Wolf investigated the photoactive self-healing properties of vitrimeric copolymers.

Photoactive materials undergo physical and chemical changes in response to illumination. The development of responsive materials to both heat and light were explored for the first time through the incorporation of functional molecular groups into the polymeric backbone of these systems.

Wright and Wolf’s focus on the molecule’s response to light also offered a new aspect into vitrimeric research compared to the previous studies, that exclusively focused on the vitrimers’ response to heat.

Figure 1. Comparison of thermoplastics and thermosets upon heating. Source

So what exactly are vitrimers? Vitrimers are a new class of polymeric material that was first created in 2011 by a Polish physicist, Dr. Ludwik Leibler. By combining characteristics of thermosets and thermoplastics, Leibler was able to develop a material that is strong and durable, yet moldable and recyclable.

Thermoplastics are made of plastics linked by intermolecular forces. They can be easily molded and shaped under heat, then cooled down to produce the final structure. This allows for ease when it comes to processing. Additionally, this property allows them to be recycled to produce new products.

Conversely, thermosets involve irreversible cross-linking, connecting the backbones of the polymer chains with molecular bridges. This results in enhanced chemical and heat resistance, making the material less susceptible to stress-cracking. However, due to their cross-linked bonds, these materials do not melt upon exposure to heat,  unable to remold and recycle.

Vitrimers combine the best properties of both materials; structural integrity is improved through cross-linking, as well as self-healing and fully recyclable properties.

Figure 2. The molecular structure of the photoactivated vitrimeric copolymer created by Wright and Wolf. Source

As seen above in Figure 2, the vertical wiggly line splits the system into the two unique parts that make this a copolymer. The left side shows the aromatic anthracene molecule that crosslinks into a dimer in response to UV radiation.  The amine on the right side behaves like a more traditional vitrimer and responds to heat to form reversible exchanges.

Originally, their aim was to create a single polymeric system that responds to both heat and light simultaneously. However, during their research, they found that amines directly bonded to the anthracene molecules simply do not engage in the bond exchange process. They believed the electronics of the ring alters the behaviour of the molecule in comparison with non-aromatic amines.

Studying the photodimerization and thermally exchangeable functionalities of the copolymer based on the vinylogous urethane vitrimer, the self-healable properties can be seen in the video above. Self- healing polymers are a class of materials that enable the repair of micro-scale damage in the coating, ultimately restoring the passive state of the metal substance.  This enables reprocessability or longer lifetimes in cross-linked polymeric materials. The systems containing anthracene undergo self-healing through reversible reactions, allowing monomers and polymer chains to link and unlink.

Figure 3. Polymer sample, P2, mounted on a glass slide. A scratch from a razor blade can be observed. Source

Wright and Wolf tested the modification of surface properties by using a razor blade to scratch a polymer sample (that Wright denoted as P2), that was mounted on a glass slide. By using optical microscopy, the scratches were observed as dark lines crossing the sample, as seen below in Figure 4. The scratches were seen to decrease in width and ultimately close during heating through a series of expansions and contractions of the material, which can be seen in the video above.

Figure 4. Optical microscope image of (a) sample P2a initial scratch, (b) P2a after heating (c) sample P2b initial scratch, (d) and (e) P2b after heating. Black scale bar is 300 μm. Source

These specific Wright and Wolf vitrimeric copolymers will not be scaled up for commercial use, due to the difficulties of incorporating the two components of the copolymer together. However, the general idea of vitrimeric materials has “almost limitless applications”. For example, they can be incorporated into products that have a long lifetime, such as shipping materials and plastic stadium seats which can be recycled into new products once they start to deteriorate.

Additionally, Wright is currently working on vitrimers that start as a viscous liquid, much like thermoplastics, that can be easily molded and processed. This possible advancement will provide more flexibility with processing the starting material and ease in the synthesis process.

~Brina, Isla and Taiki (Group 4)

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Fallible Fingerprints

Posted on March 20, 2019 by | 3 comments

Before DNA evidence became the golden standard for forensic labs, convicting a criminal often meant dusting the crime scene for prints.

All forensic evidence are liable to error and fingerprints are no exception. In general, there are two types of error: false negative and false positive. A false negative occurs when the two fingerprints are a match but the examiner declares the fingerprints to be different. A false positive is when two fingerprints are not a match but the examiner concluded otherwise. In both cases the consequences are different, while false negatives may not entirely exonerate a criminal, false positives can lead to wrongful convictions where an innocent person can face jail time for something they did not do.

Example of a fingerprint Source: Wikimedia Commons

There are eight common fingerprint patterns: arches, tented arches, right loops, left loops, plain whorls, central pocket loops and double loops. When the lines or ridges on a finger develops and meets other ridges, the two ridges can interact in many ways, resulting in what is called a minutiae. Since fingerprints depend both on genetic and environmental factors, the patterns developed are very unique. Even identical twins can develop different fingerprints. However, theory and practice can be very different. In the modern age, there still is not a definitive certainty in how unique the match between fingerprints are. It was claimed that a false positive was one in 64 million. In one study, researchers found fingerprint exams had a false positive error rate of 0.1% and a false negative rate of 7.5%. These numbers show that human error and the quality of fingerprints can significantly influence how forensic experts perceive the evidence.

In the famous case of the Madrid train bombings, Brandon Mayfield was wrongfully convicted based on fingerprints that were found at the scene due to poor quality of the fingerprints. Later on, when the five fingerprint experts were asked to re-examine these prints, three experts reversed their conclusion and claimed the results were inconclusive. In conclusion, while fingerprints are a useful tool, they are not infallible and prone to human error more than one expects.

(1)
Knapton, S. Why Your Fingerprints May Not Be Unique. The Telegraph. March 14, 2016.
(2)
The “CSI Effect.” The Economist. April 22, 2010.
(3)
Statement on Brandon Mayfield Case https://www.fbi.gov/news/pressrel/press-releases/statement-on-brandon-mayfield-case (accessed Mar 20, 2019).
(4)
Latent Print Examination and Human Factors: Improving the Practice through a Systems Approach. 249.
(5)
Latent Print Examination and Human Factors Improv.Pdf.
(6)
God’s signature: DNA profiling, the new gold standard in forensic science. – PubMed – NCBI https://www.ncbi.nlm.nih.gov/pubmed/12798816 (accessed Mar 20, 2019).
(7)
Stephanie. False Positive and False Negative: Definition and Examples https://www.statisticshowto.datasciencecentral.com/false-positive-definition-and-examples/ (accessed Mar 20, 2019).
(8)
Photographer, T. English: Fingerprint; 2009.
(9)
Spiro, R. Do Identical Twins Have Identical Fingerprints? | Washington State Twin Registry | Washington State University. Washington State Twin Registry, 2015.
(10)
14 Amazing Forensic Science Techniques.
(11)
8 Most Common Fingerprint Patterns. Touch N Go, 2017.

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The Link Between Stress and Technology

Posted on March 6, 2019 by | 3 comments
Whether it is stress over a failed exam, or feeling stress when put in a new environment, we have all experienced stress before and know that being stressed is not a good feeling.

Figure 1. Participants rate their stress level on a scale of 1-10, where 1 equals “little or no stress” and 10 means you have “a great deal of stress”. Photo source: American Psychological Association

Although stress usually has a bad connotation associated with it, there is also positive stress. For example, positive stress can motivate you and help you complete tasks more efficiently. However, high levels of stress can lead to anxiety, depression, high blood pressure, and other chronic illnesses. Stress levels found in humans have increased drastically over the years and may be a concern to a high percentage of the human population. There are many factors that can explain the increase in stress over the generations, but let’s focus on one that we are all familiar with: technology.

Could the increase in stress over the years be linked to technology use?

Let’s first look at smartphone ownership over the recent years.  In 1992, the first smartphone, the Simon Personal Communicator by IBM, was introduced and 15 years later, the first iphone was produced. The popularity did not start immediately and only began increasing around 2011, where approximately 35% of U.S. adults owned a smartphone. The percentage quickly ascended over the next 6 years to 77%. With more advances in technology, people are now overly dependent on their smartphones. But, who can blame us for being overly dependent on our smartphones? Not only can it take high quality videos/photos, but you can even pay with smartphones nowadays – it’s all just one tap away.

                             Figure 1. Smartphone Ownership                                Adapted from: Pew Research Center – Internet & Technology

So, what evidence is there that proves that technology adds stress to our lives? Well, sleeping patterns can be easily affected by technology, one second you’re getting ready for bed, and the next second you are asking your friends whether the dress is black and blue, or white and gold and then you realize it’s way past your bedtime. The constant distractions our smartphones present make us less efficient when completing tasks as simple as going to bed at an appropriate time.

Image result for blue light screens

Photo source: Lifewire

Furthermore, the blue light emitted from our phone screens can reduce melatonin production, which reduces your sleep quality. When sleep quality is reduced, one then becomes less resilient and stress levels and anxiety increase.

In conclusion, it is evident that the accessibility and convenience of technology can negatively affect our living qualities by causing stress levels to rise. As stated above, sleep is easily affected by technology use and sleep is crucial for out bodies to function properly. Therefore, although technology can be very handy, one should be aware of the effects of technology on your stress levels.

Watch the following video for more information on the effects of technology:

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Is Machine Learning the Future of Technology Development and Chemistry Research?

Posted on March 1, 2019 by | 4 comments

The ability for scientist to develop new drugs for everything from rare diseases to headaches is often reliant on precedent and systematic investigations. These methods are often costly and time consuming. Similar problems arise in development of new materials that may enhance our energy production. Our limited ability to rationally design materials  hampers their development. This leads to reliance on our ability to recognize the trends and behavior of already existing materials. However, what if we could amplify the ability to recognize patterns beyond human limits? Machine learning answers this problem.

A graph depicting the general algorithm machine learning follows. Source: Wikimedia Commons

While machine learning is a form artificial intelligence, our jobs are safe. Machine learning is the use of statistics and the power of computers to predict results or identify trends in data. The general method relies on the input of “training” data which is analyzed using statistics. After developing a model, information may be inferred from new data the computer encounters.

-Video Source: Google Cloud Platform educational AI Adventures Series on YouTube by Yufeng Guo in 2017.

Large technology companies have recognized the advantage of integrating machine learning into technology development. Google is one example that has successfully introduced it. Gmail uses machine learning to service 1.5 billion active accounts. They claim to detect 99.9% of phishing and spam mail from entering the user’s inbox. However, machine learning is not limited to technology companies. Chemistry researchers have quickly adopted it.

Total Number of Chemistry Publications with “Machine Learning” in Title

Starting in 1969, the first chemistry journal article with “machine learning” in the title was published. By combining machine learning with a common technique called mass spectrometry, Peter Jurs at the University of Washington was able to determine chemical composition of “unknown” chemicals using the input of 348 unique patterns as “training” data.

More recently there has been an almost exponential increase in the number of chemistry publications applying machine learning. In the last two years approximately 6 times as many publications were made than in the past 48 years. Tommi Jaakkola, a Professor of Electrical Engineering and Computer Science at MIT said at a consortium about implementing machine learning in the pharmaceutical industry: “by marrying chemical insights with modern machine learning concepts and methods, we are opening new avenues for designing, understanding, optimizing, and synthesizing drugs.” The materials science community has also seen integration with the development of novel long chained molecules called polymers for photovoltaics by scientist at Osaka University. Shinji Nagasawa, the lead author explained the importance: “there’s no easy way to design polymers with improved properties. Traditional chemical knowledge isn’t enough. Instead, we used artificial intelligence to guide the design process.”

Solar cell efficiency over years showing a substantial increase. Source: Wikimedia Commons

While machine learning is not the solution to all chemical problems or spam mail, it is being widely accepted by the scientific community and technology industry for good reasons. Even with limitations, it’s effectiveness across a wide array of industry and research emphasizes the role it may play in the future of research and development.

—Jonah

References

  1. Graph-powerd Machine Learning at Google. Google AI Blog. https://ai.googleblog.com/2016/10/graph-powered-machine-learning-at-google.html (Accessed Feb 28, 2019).
  2. Jurs, P.C.; Kowalski, B.R.; Isenhour, T.L. Computerized Learning Machines Applied to Chemical Problems: Molecular Formula Determination From Low Resolution Mass Spectrometry. Chem. 1967, 41, 21-27.
  3. Machine Learning, Materials Science and the New Imperial MOOC. Imperial College London. https://www.imperial.ac.uk/news/187054/machine-learning-materials-science-imperial-mooc/ (Accessed Feb 28, 2019).
  4. UBC Summons. University of British Columbia.

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Record Breaking Temperatures in Superconductive Materials

Posted on January 22, 2019 by | Leave a comment

More than 100 years ago a Dutch scientist named Heike Kamerlingh Onnes at Leiden University discovered a phenomenon in mercury know as superconductivity. When cooled to -269°C the mercury exhibited zero electrical resistance unlike conventional materials that release heat when transporting electricity.

Why is this important if it requires such a cold temperature? Over the past 100 years scientist and engineers have incorporated this phenomenon into our daily lives. This allowed for dramatic advancements in medicine such as the development of the MRI. Our power grid also takes advantage of this weird property. However, only select materials exhibit superconductivity when cooled below a temperature referred to as the critical temperature.

An example of a superconducting radio frequency cavity on display at Fermilab made of Niobium, a common metal in superconductivity applications. Source: Wikimedia Commons

In 1987 the technology was revolutionized when a material called yttrium barium cuprate was found to exhibit superconductivity below -181°C. This temperature is easily reached with liquid nitrogen, a widely accessible coolant. This marvelous material has found itself applied at the Large Hadron Collider in Geneva and most hospitals. While materials with higher critical temperatures have been slowly discovered, recent advancements have been shattering the records.

Timeline of Superconductive Materials
Source: Wikimedia Commons

Among these superconductors are a class which only exist at extremely high pressures. The smelly gas that comes from volcanos and is reminiscent of rotten eggs, Hydrogen sulfide (H2S), is one of these. When cooled to -70°C at 1.5 million atmospheres, hydrogen sulfide exhibits an exotic form of high pressure superconductivity. This discovery in 2015 by Mikhail Eremets and Alexander Drozdov at the Max Plank Institute for Chemistry in Mainz, Germany toppled previous records by 39°C, a significant breakthrough in the search for room temperature superconducting materials. Mikhail Eremets said: “Our research into hydrogen sulfide has however shown that many hydrogen-rich materials can have a high transition temperature.”

This has held true with a recently published paper by the same team in December of 2018. Lanthanum superhydride (LaH10) was found to be superconducting at -23°C, however it was at similar pressures to the previous discovery. This value was found to be even higher at -13°C when pressurized up to 2 million atmospheres as published by scientist at George Washington University in January of 2018. Maddury Somayazuli, an associate professor at The George Washington School of Engineering and Applied Science said: “Room temperature superconductivity has been the proverbial ‘holy grail’ waiting to be found, and achieving it-albeit at 2 million atmospheres-is a paradigm-changing moment in the history of science.” Future experiments are expected to provide more breakthroughs in the field.

An engineer at the Advanced Photon Source, part of Argonne National Laboratory where GW University experiments were preformed. Source: Advanced Photon Source Flicker (CC BY-NC-SA 2.0)

While high pressure superconductors lack application, understanding this  property may allow for the development of new materials. With continued research and the recent breakthroughs, the phenomenon of superconductivity may further be propelled into future technology that will have a significant impact on our quality of life.

-Jonah

References:

1.Drozdov et al, “Superconductivity at 250K in Lanthanum Hydride Under High Pressure,” arXiv:1812.0156 [cond-mat], Dec. 2018.                                        2.Somayazuli et al. (2019). Evidence for Superconductivity above 260K in Lanthanum Superhydride at Megabar Pressures. Physics Review Letters, (122), 027001-6.                                                                                                              3.Researchers Discover New Evidence of Superconductivity at Near Room Temperature. (2019, January 15). Phys.org. Retrieved from https://phys.org/news/2019-01-evidence-superconductivity-room-temperature.html                                                                                      4.Superconductivity: No Resistance at Record Temperatures. (2015, August 18). Max-Planck-Gesellschaft. Retriever from https://www.mpg.de/9366213/superconductivity-hydrogen-sulfide                  5.Eck, J. (2018). The History of Superconductors. Retrieved from http://www.superconductors.org/History.htm

 

 

 

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