Hidden Chemicals in Children’s Toys

                                                                                               Posted by Bray Fedele

When considering the places cancer causing chemicals could be hiding, children’s toys are likely not the first category that comes to mind. Dr. Stapleton, a chemist at Duke University, was among the masses who did not previously consider toys for children we strenuously attempt to protect to be home to several “lurking” chemicals. After noticing a familiar flammability standard tag on her one year old’s play tunnel, Stapleton, being the resourceful chemist she is, immediately took a piece of the tunnel to her lab for analysis. Having already researched the effects and presence of flame retardants on human health, she was horrified by what she found.

Stapleton was shocked to find a flame retardant, chlorinated tris, which was banned for use by manufacturers in baby clothes years prior for its ability to alter DNA and even cause cancer. So what was this chemical doing so unquestioned in presumably safe baby toys?

Figure One: Chlorinated tris, a commonly used and toxic flame retardant.

 The use of flame retardants in different materials began in the 1970s in order to meet flammability requirements. Since then, chemists have raised several concerns about the role of formulations with bromine, chlorine, and phosphorus in the development of serious diseases and even death. These chemicals, once in fabrics and other home materials, have the potential to escape into the air and enter the human body as dust (usually by small children putting their hands and other materials in their mouths). These specific chemicals used in flame retardants have been associated with cancer, disruption of hormones, harm to the reproductive system, neurodevelopmental problems, lower I.Q., and even behavioral problems. In fact, brominated flame retardants have recently taken the crown as the major cause of I.Q. loss and intellectual disability in children.

Figure Two: Most common flame retardants used as of 2019. 

Despite these findings, flame retardants are loosely regulated, and have never been banned federally (as of 2020). Manufacturers easily find loopholes in producing their goods with harmful retardants by constantly changing the type, in order to stay ahead of scientists. For example, a chemist at the University of California successfully proved the association of brominated tris and cancer in 1977, but manufacturers quickly avoided the problem by switching to a close relative, chlorinated tris. Thus, scientists had to work at a rapid pace to constantly prove the detrimental effects of different flame retardants, and still are not fully able to ban their use entirely. There is a never ending list of flame retardants being used by manufacturers, making it almost impossible for scientists to identify them all, let alone test them for safety and reliability. In addition, the full discontinuation of toxic flame retardants is seemingly a complicated endeavor, as the use of chlorinated tris has been removed from the manufacturing process of children’s clothes over 40 years ago, yet it is still used in baby toys.

Figure Three: Types of brominated flame retardants. 

In 2017, scientists discovered that mothers had 15 times less flame retardant concentration in their urine than their children. Upon further investigation, there was an

association determined between the number of baby toys in the home and the concentration of flame retardants in the child’s urine (the more toys, the higher the concentration). Such findings are extremely worrisome considering the previously discovered health effects of flame retardants and their threat towards crucial development expected in the first year of life (and throughout adolescence). Scientists like Dr. Stapleton and many others have made it their mission to have these toxic chemicals banned from household items for good, but it is a slow and daunting process and ultimately needs federal support in order to ease the minds of parents and to save the lives of children.

Sources:

1. Gross, L. (2020, November 23). The harmful chemical lurking in your children's toys. The New York Times. Retrieved November 15, 2021, from https://www.nytimes.com/2020/11/23/parenting/home-flame-retardants-dangers.html.

2. The flame retardants market. FLAMERETARDANTS. (n.d.). Retrieved November 15, 2021, from https://www.flameretardants-online.com/flame-retardants/market. 

 

                                       Lithium battery vs hydrogen fuel cell

                                                        view one

Elon Musk: Hydrogen fuel cells are "incredibly stupid"! 

As early as 2015, he claimed: "If you want to choose an energy storage mechanism, you should choose methane or propane, because they are easier to produce." Musk said: "I just think (hydrogen fuel cell) is very stupid... .... It is very difficult to make hydrogen, store it and use it in a car.", "If you take a solar panel to directly charge the battery pack, compared with electrolysis, hydrogen is taken, oxygen is separated, and hydrogen is compressed... .. This is about half of its efficiency."

In fact, Musk's words are not unreasonable. Compared with batteries, the energy conversion efficiency of hydrogen fuel cells is always lower than that of batteries. Compared with Tesla’s BEV efficiency, the best FCV currently on the market is still less than half of the BEV in efficiency; in addition, the development of the industrial chain In terms of infrastructure (hydrogen refueling station) construction, the gap between hydrogen fuel cells and lithium batteries is still decades away.

The development of fuel cells continues, but the charging infrastructure, the mass production of hydrogen, and its inventory are lagging behind. The use of hydrogen requires a lot of infrastructure construction, high quality, and large pressure accumulators. The production of fuel cells, pressure tanks (carbon fiber), the price of hydrogen for refueling, the infrastructure of hydrogen refueling stations, and the construction of H2 production facilities are all too expensive. In addition, at present, thermochemical processes using fossil energy as raw materials are widely used in industry, mainly including hydrogen production methods such as hydrocarbon steam reforming, heavy oil partial oxidation, coal gasification, and water electrolysis. In the mainstream hydrogen production process, there are also problems of pollution and low efficiency.

View Two:

"The future market belongs to fuel cells"

For many years, Toyota has been betting hydrogen fuel cells on battery electric vehicles to achieve its zero-emission vehicle strategy. Toyota's fuel hydrogen battery is an advanced technology used by Toyota in Mirai's new energy vehicles. Toyota hydrogen fuel cell is like a power station. It produces electricity through the chemical reaction of oxygen and hydrogen. It does not need to be charged like ordinary storage batteries. Only need to add hydrogen to produce electricity through chemical reactions.

The battery life advantage of the hydrogen fuel cells is also obvious compared with lithium batteries. It also has a battery life of 500 kilometers. It takes a long time for an ordinary lithium battery to charge, super fast charge also takes one and a half hours, and hydrogen dye battery can be filled with hydrogen in only 3 minutes. . In addition, hydrogen far surpasses lithium-ion in energy density, and the two are not even on the same order of magnitude.

Hydrogen fuel cell vehicles also have the following advantages:

1. Hydrogenation is like refueling, usually only 3~5 minutes. The charging of electric vehicles is a slow process. Even if Tesla launches a supercharging station, it usually takes more than an hour.

2. The main component of a hydrogen fuel cell is hydrogen. We know that the chemical formula of water is oxygen dihydrogen. The hydrogen fuel cell will not pollute the environment after the end of its service life. Lithium-ion batteries contain a lot of heavy metals. If they are not recycled properly, they will cause greater pollution to the environment.

3. Hydrogen fuel cells have high energy storage density, lightweight, and generally longer cruising range. Usually, more than 500 kilometers and pure electric vehicles are based on the size of the battery capacity. At present, most pure electric vehicles have a cruising range of about 300 kilometers, and a few models can reach 400 to 500 kilometers.

Fuel cell vs lithium-ion battery

Currently, the global energy and environmental systems are facing huge challenges. Among them, the automobile industry, which is a major consumer of oil and carbon dioxide, is also facing a revolutionary change. The use of pure electric drive including pure electric and fuel cell technology as the main technical direction of new energy vehicles has become the world Consensus formed by various countries. Fuel cell vehicles are another important direction of electric vehicle batteries. Compared with lithium-ion batteries, it can be clearly seen that there are obvious advantages and disadvantages between the two.

First of all, it is from the perspective of security.

Safety hazards of fuel cells: Leakage and control of hydrogen is the main source of safety hazards in fuel cell systems, which belong to the physical level, while the safety hazards of lithium-ion batteries mainly come from chain reactions that are not easy to control, which belong to the chemical level. Because the chain reaction speed is extremely short. In terms of controllability, the control difficulty of lithium-ion batteries is higher than that of fuel cells. However, in the case of extreme violent collisions, the degree of harm to fuel cells is even greater. Of course, this is only in theory. The hydrogen itself has a short leakage time due to its fast escape. In addition, the high-pressure hydrogen cylinder is resistant to impacts, drops, gunshots, and other unconventional properties that also provide security.

Secondly, from the perspective of low-temperature performance.

Because the viscosity of the electrolyte increases at low temperatures, the conductivity decreases, which will lead to a sharp increase in the internal polarization of the battery. Generally, manufacturers do not recommend sub-zero discharge behavior. Therefore, lithium batteries need external heating to solve the low-temperature problem. The low-temperature start performance of the fuel cell is poor, but with the increase of its own heat release after startup, the temperature of the stack will quickly stabilize in the normal operating temperature range of 80-90°C. However, how to achieve low-temperature startup of fuel cells, especially low-temperature startup under the premise of not using external auxiliary power, is an important research topic.

Third, it is from the perspective of cost.

On the whole, whether it is a fuel cell or a lithium-ion battery, the price is higher than that of traditional energy sources. In particular, the complexity and harsh conditions of the source, storage, and safe use of hydrogen have resulted in high costs for hydrogen fuel cells, making it difficult to gain advantages in the short term. Judging from the mass production data, the cost of fuel cells is still very high, and it is expected that the price of internal combustion engines may be close to the current price of internal combustion engines under the premise of long-term mass realization.

Fourth, the time it takes to charge.

Long charging time is always an indelible pain point for lithium-ion batteries. In the normal charging mode, a car equipped with a lithium-ion battery takes 3 to 8 hours to fully charge. In contrast, fuel cells are much more convenient and fast. Taking hydrogen fuel cells as an example, it only takes 3 to 5 minutes to directly add hydrogen to resurrect with full blood.

Fifth, the cruising range.

This may be the biggest pain point for pure electric vehicles, especially lithium-ion battery vehicles. It is difficult for traditional lithium-ion batteries to exceed 500km in endurance. In contrast, fuel cells with high energy density and lighter weight can reach farther in endurance.

Sixth: Temperature influence.

Fuel cell vehicles can maintain the same long cruising range as in summer through the integrated thermal management of the entire vehicle. This is something that lithium-ion batteries cannot do. Lithium-ion batteries consume power regardless of whether it is PTC heating or air conditioning heating. The fuel cell consumes electricity to power the air conditioner in the summer, while in the winter it only uses waste heat to keep the passenger compartment warm. So theoretically, the mileage in winter should be longer than in summer. At present, there are institutions that are carrying out research on waste heat power generation based on the Rankine cycle. If it can be realized, it will further improve the efficiency of fuel cells.

Seventh: Cost balance.

Fuel cell and pure electric vehicles have different cost balance points. Passenger cars are about 500 kilometers away, and commercial vehicles are about 100 kilometers 

Reference:

1].https://www.fz-juelich.de/portal/DE/Forschung/EnergieUmwelt/energiewende.html

[2].https://www.chemie.de/news/1153224/batterie-oder-brennstoffzelle.html

[3].https://traveltosetna.wordpress.com/2018/10/08/brennstoffzelle-lithium-ionen-akku-feststoffzelle-was-ist-besser/

[4]. https://www.zhihu.com/question/19986795

[5]. http://www.sohu.com/a/204402016_15

New Quarantine Activity: Firing Medieval Cannonballs

                                                                                                            Posted by Ava Sheftik

 An article titled “This Chemist’s Pandemic Hobby? Firing Medieval Cannonballs” found in the New York Times discusses an activity of Dr. Dawn Riegner, a professor of chemistry at the United States Military Academy West Point, early quarantine activity. She convinced her colleagues and daughter into beginning a study on how well different kinds of gunpowder recipes from the Middle Ages performed.

Their report on their gunpowder analysis was featured in Omega which is a peer reviewed journal of the American Chemical Society. The purpose of their experiment was to determine if the creators in the medieval time period actually understand the chemical characteristics of their materials and processes that they were completing. They analyzed gunpowder recipes which consisted of potassium nitrate (KNO3), charcoal (C), and sulfur (S8) by bomb calorimetry. They then used this to determine their enthalpies of combustion and differential scanning calorimetry to determine their pre-ignition and propagative ignition enthalpies.

The cannon used for the range tests was a reproduction of a Steinbüchse, which is a stone throwing cannon, copied from an extant gun from the 15th century. For safety reasons the gun had some alterations but nothing that should have affected the shot.

Figure 1. Heats of Combustion for Each recipe in Chronological order

This figure represents the thermodynamic potential of gunpowder recipes in chronological order. The suggestion for the change in these recipes is because they needed to have safer ones that did not put the gunners at risk or damage the cannons. The trend observed is that the closer the KNO3:C ratio is, the heat of combustion will be higher and reaction rate will be faster.

The bomb calorimetry data shows that increasing the percent of charcoal will lead to a higher heat of combustion. Furthermore, most samples that were pressed produced a slightly lower thermodynamic potential. This may be due to the lack of oxygen ability to enter to materials due to the lack of spacing between the particles in the pressed sample. Therefore, incomplete combustion would be the result and is the explanation for the smaller enthalpies observed for the pressed samples.

There were several additives also tested: water, varnish, vinegar, and brandy.

It was determined that the addition of water and its effect on enthalpy was specific to each different recipe. However, the addition of varnish to a recipe with high charcoal content and relatively low sulfur content decreases the potential energy measured by the bomb calorimeter. The varnish can provide clumping of the ingredients and prevent sulfur from mixing and which then decreases the surface area of the charcoal.

The addition of brandy as a corning agent did not show a significant increase in the heat of combustion. The suggested reason for this is that it provided missing organic compounds for better quality burning

 Figure 2. Addition of varnish

Figure 3. Addition of Brandy

The addition of vinegar requires further studies to come to an ultimate conclusion. It was added to enhance mixing of dry ingredients so that they didn’t separate during transport. Some recipes produced a result that was similar to water, some yielded a lower enthalpy, and some yielded higher.

Figure 4. Pre 1400 vs. Post 1400 ingredient ratios and their impact on the heat of combustion

As time progressed throughout 1300s to1400s the recipe creators were creating a formula that would provide them with a lower heat of combustion which involved increasing the amount of potassium nitrate. After the 1400s the heat of combustion rose again and the potassium nitrate decreased.

These advancements completely changed the nature of warfare during the time period. Sieges that used to take years and months began to only take weeks and days. The guns were now safer for the gunners; however, they became larger and more effective in their use.

References

Broad, William J. “This Chemist's Pandemic Hobby? Firing Medieval Cannonballs.” The New York Times, The New York Times, 7 Oct. 2021, https://www.nytimes.com/2021/10/07/science/gunpowder-medieval-cannons.html.

Ritchie, T. S.; Riegner, K. E.; Seals, R. J.; Rogers, C. J.; Riegner, D. E. Evolution of Medieval Gunpowder: Thermodynamic and Combustion Analysis. ACS Omega 2021, 6 (35), 22848– 22856. 

 

Bombs Away!

 During the beginning stages of the Covid-19 pandemic in 2020, many of us were using our time in quarantine to practice new hobbies such as baking bread, making whipped coffee, or hoarding toilet paper. For students and researchers at the United States Military Academy in West Point, New York, however, time in quarantine took a more explosive turn. In his article "This Chemist’s Pandemic Hobby? Firing Medieval Cannonballs" for the New York Times, author William Broad chronicles Dr. Dawn Reigner and her team as they tested different medieval recipes for gunpowder to discover what causes the most reactive explosions - and further understand how this chemical innovation changed the course of history forever.

The commonly known, tried and true recipe for gunpowder has consisted of saltpeter (potassium nitrate), carbon, and sulfur. These ingredients create an exothermic reaction that is used to propel bullets, cannonballs, and other similar weapons. Recipes date back centuries and all include these three main ingredients. Interestingly, there are medieval records of less common ingredients being added to the mixture such as brandy, vinegar, and quicklime were added in small quantities. Dr. Reigner and her team decided to test these additions to find the recipe for the most efficient gunpowder.

Figure 1: Simple equation for the combustion reaction of gunpowder

Broad notes in his article that gunpowder changed the nature of warfare, in that kingdoms needed armies as opposed to simply fortresses. Perfecting the recipe of gunpowder was also necessary, as large explosions would kill or maim those wielding the weapons themselves.

Dr. Reigner's group noted that in trying to create more effective explosions that were safe for the user, recipes were tweaked so as to lower the heat of combustion to safer levels while still having a large enough blast to damage structures and maim enemies. The researchers noted the changes over time and compared them to their own bomb calorimeter data.

Figure 2: Mass percentages of gunpowder components over time and bomb calorimeter data

Their research showed that the data surrounding the interesting additions to the recipes, like brandy, were inconclusive but did not show measurable difference. The biggest effect on the heat of combustion was the amount of saltpeter, also the most expensive ingredient, which was lessened in post-1400 recipes. Reigner's research shows that the trial and error method that medieval people used to perfect gunpowder is not dissimilar from the way research is conducted today, and that even in the 1300's people were striving to understand and perfect the way things are done.

References

Broad, W. This Chemist’s Pandemic Hobby? Firing Medieval Cannonballs. The New York Times, October 2021, Retrieved from https://www.nytimes.com/2021/10/07/science/gunpowder-medieval-cannons.html

ACS Omega 2021, 6, 35, 22848–22856

Publication Date:August 24, 2021

https://doi.org/10.1021/acsomega.1c03380

Coffee, Climate Change and Why We Need to Save the Planet NOW!

 New study shows that the growth of species of coffee plants (Coffee Arabica and Coffee Canephora) is negatively impacted by climate change. 

Close your eyes and picture this scene: You're sitting at your desk, early in the morning, dreading the work day ahead of you. You didn't get good sleep the night before and can feel the stinging in your eyes caused from a lack of sleep. Then you take a deep breath in, and as you breathe in you get a whiff of a subtle, roasted, slightly fruity aroma. The smell of caramel fills up your nose as well as the warmth of steam. You turn around and see that the coffee you were brewing is now ready to drink. Your mood changes as you grab that warm cup of happiness containing a little piece of heaven and bring it to your lips, and from the first sip you feel energy and positivity flow in and your outlook changes. Supposedly. I am not a coffee drinker myself but I have heard wonders about this magic drink. Regardless of your stance, that warm cup of coffee may begin to taste different as time goes on and may begin to smell worse and it's all due to climate change. 

A new study conducted by a research group in Tufts and Montana State University's Friedman School of Nutrition Sciences and Policy shows how a variety of environmental factors are negatively affecting the quality of coffee that is grown, affecting the coffee's aroma and taste (ScienceDaily, 2021). The study also found that apparently the quality of the coffee is affected by shifts in the climate occurring due to climate change as well. 

The quality of the coffee was determined based upon sensory attributes (Aroma and taste) as well as the presence of primary and secondary metabolites. The primary metabolites and secondary metabolites present in these coffee species include things such as sugars, lipids, vitamins and minerals as well as caffeine, trigonelline, chlorogenic acids and terpenoids some of which are depicted in the figures below. 

From left to right: Caffeine, trigonelline and isoprene, a type of terpenoid.

The study found that 2 factors were the most significant in affecting the quality of the coffee: the altitude in which the coffee is grown at as well as the amount of exposure it has to sunlight (Ahmed et. all, 2021). Some of the other environmental factors that affect the quality of the coffee's taste and aroma include water stress, increasing temperatures and increased carbon dioxide emissions. These environmental factors play an important role in determining where suitable places for coffee growth are however. The top 2 factors of altitude and sunlight exposure are geographical variables, however the other factors such as water stress and increasing temperatures are directly linked to climate change. Because of this, the lands that were once suitable for coffee production are now losing their quality. 

The figures above show the results found from the research study, which show that an increase in altitude results in higher quality coffee and that increased light exposure results in lower quality coffee. 

An example of lands that are losing their coffee production abilities can be found in Nicaragua. According to various projections, 90% of the coffee growing land in Nicaragua will disappear by the year 2050 due to changes in the climate that will occur. Conversely, coffee producing regions in East Africa and Asia have been identified as becoming spaces that are more suitable for coffee production in the near future, due to climate change. However, in order for these lands to access these new will cause for deforestation to occur, which will impact the biodiversity of the regions and have other negative effects such as increased gas emissions.

Some of the solutions that the study found that could work are shade management, pest management and selecting for climate-resistant wild coffee plants. However these are short terms solutions that won't really combat the long term drastic effects of climate change. In order to truly save our coffee and our planet we must look to long term solutions that will have a more permanent effect on the climate. 

Author: Anas Mahmoud 

References

Ahmed, S., Brinkley, S., Smith, E., Sela, A., Theisen, M., Thibodeau, C., Warne, T., Anderson, E., Van Dusen, N., Giuliano, P., Ionescu, K. E., & Cash, S. B. (1AD, January 1). Climate change and coffee quality: Systematic review on the effects of environmental and management variation on secondary metabolites and sensory attributes of Coffea Arabica and Coffea canephora. Frontiers. Retrieved November 2, 2021, from https://www.frontiersin.org/articles/10.3389/fpls.2021.708013/full. 

Isoprene. ChemSpider. (n.d.). Retrieved November 2, 2021, from http://www.chemspider.com/Chemical-Structure.6309.html?rid=05410d7d-dfb5-4ca1-a2f8-46e2f841ed01. 

Snider, M. (2021, September 2). Go ahead, have that Third Cup of coffee. you just might live longer, new research suggests. USA Today. Retrieved November 2, 2021, from https://www.usatoday.com/story/news/health/2021/09/02/how-much-coffee-healthy-three-cups-reduce-heart-attack-risk/5668047001/. 

Putting an End to Toxic 'Forever Chemicals'

 In The NBC article “Toxic ‘Forever Chemicals’ are Everywhere. The EPA has a New Plan to Crack Down”, Leigh Ann Caldwell and Frank Thorp V explain the crisis on PFAs and the steps that are being followed in order to protect the nation from these harmful chemicals. 

Figure 1: The chemical structure of PFAs.

PFAs, commonly referred to as “forever chemicals” are materials that cannot be broken down due to strong carbon-fluoride bonds. These chemicals are able to seep into groundwater or released into the air and cause harmful health conditions such as high cholesterol, immunosuppression, infertility, cancers, and reduced vaccine efficiency.  Two of the biggest polluters of these PFAs are the Department of Defense and the chemical manufacturers. These polluters are consequently infecting people that live in these areas, such as the instance mentioned in the article where a woman grew up next to a Navy base and possibly ingested these chemicals. As a result, she developed melanoma at the age of 25.

Figure 2: Naval Air Development Center in Warminster, Pennsylvania.

Although these organizations are responsible for environmental pollution of PFAs, they are not the only source. Food packaging products, pans, clothes, shoes, carpets, and cosmetics are also found to have these toxic chemicals within them. 

Figure 3: Examples of products that contain PFAs.

The issue has been known for quite some time now, but the only action that was taken was the monitoring of water near contamination sites. Even then, very little has been done to rectify the contamination. Now, the EPA is creating a plan to implement new requirements and restrictions for drinking water PFA contamination. These regulations will be set by Fall of 2023. In this plan, the amount of PFAs present in drinking water must in the acceptable range, which the FDA recommends to be 70 parts per trillion. The EDA is also planning to restrict companies from dumping these chemicals into waterways. In October, California has banned the use of PFAs in baby and toddler products and these type of actions are likely to be followed by other states, as well.

Sources: 

https://www.nbcnews.com/politics/politics-news/can-epa-get-rid-toxic-forever-chemicals-n1281707

https://www.pfasfacts.com/

https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.riversideca.gov%2Fpress%2Funderstanding-pfas&psig=AOvVaw16g0ZO0biEFG0Qw3uLWoAa&ust=1635864463032000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCPjinJe09_MCFQAAAAAdAAAAABAX

Recent Analysis Shows Modifications Made to Lavoisier Painting

 

They say that history is written by the victors. In Antoine Lavoisier’s case, he was not one of them. It’s a well-known fact that he was denounced and guillotined in 1794 for being a wealthy tax collector, during the French Revolution. He was, of course, also a famous and brilliant chemist, whose influence in the field cannot be understated (earning him the moniker ‘the father of modern chemistry”). Recent analysis of a famous 1788 painting of him and his wife, Marie-Anne, shows that the painting was modified to show less of his wealth and more of his science. 

Dorothy Mahon, a conservator at The Metropolitan Museum of Art, noticed some oddities in the painting while carefully removing a degraded layer of varnish. Cracks in the paint seemed to show other colors beneath, and tiny cracks on the tablecloth seemed to reveal that the final layer of paint was a later addition. This prompted further analysis. 

 

Fig. 1: Signs of the original painting showing through the top coating

Firstly, infrared ray reflectography was utilized to reveal what lay beneath the painting’s surface. IRR is a technique where infrared light is cast on the painting, which can pass through the surface layer. By measuring the infrared light that’s reflected by different areas of the painting, things underneath the surface can be seen. The IRR applied to this painting showed several things -- the initial sketch that was painted over being modified several times, changes in facial expressions, a wastepaper basket that was removed from the final product. Most interestingly, it revealed several discontinuities that weren’t as easily explained by the painting process -- an elaborate table under the tablecloth, a blurry object on the table, a strange smudge on Marie-Anne’s head. 

This prompted further analysis. For a more accurate view of what lay beneath, macro X-ray fluorescence mapping was utilized. This technique uses X-rays to detect the elements in a sample. The X-rays bombard the sample, and the emitted energy is measured. These emissions are cross-referenced with atomic spectral lines to determine the composition. Once the elements in a sample are known, it can be inferred what pigments were used to color the painting, and it can thus be determined what the painting looks like under the surface. To help with determining which pigments were used, seven small paint samples were taken from the painting and analyzed. 

The macro X-ray fluorescence elucidated the changes to the painting. Most prominently, Marie-Anne originally had a large flamboyant hat, with ribbons and feathers. The table was originally a lavishly gilded wood, before it was covered in the red tablecloth seen today. Some of the scientific instruments in the painting were added later, and Lavoisier was originally wearing a red mantle that was removed. All in all, the painting was modified to show much less wealth, and instead focus on Lavoisier’s scientific pursuits. 

 

Fig 2: The image as it is seen now, under IRR imaging, and reconstructed after MA-XRF analysis

The painting has since been revarnished and sits at The Met, the same as it always has. It looks the same as it did before, of course, showing Lavoisier and his wife as the great scientific couple they always were. But it’s worth thinking about, now, how carefully that image was chosen to depict them as it does. 

References:

Blakemore, Erin. "Tech Uncovers Changes to Portrait of a Chemist-Couple, Victims of Reign of

    Terror." The Washington Post, 11 Sept. 2021, www.washingtonpost.com/science/

    art-restoration-science-met-lavoisier/2021/09/10/f2100e0a-10dc-11ec-9cb6-bf9351a25799_story.html.

    Accessed 26 Oct. 2021.

Centeno, Silvia A., et al. “Discovering the Evolution of Jacques-Louis David’s Portrait of Antoine-Laurent and Marie-Anne Pierrette Paulze Lavoisier.” Heritage Science, vol. 9, no. 1, Springer Science and Business Media LLC, 30 Aug. 2021. Crossref, doi:10.1186/s40494-021-00551-y. 

Centeno, Sylvia A., et al. "Refashioning the Lavoisiers." The Metropolitan Museum of Art, 1 Sept.

    2021, www.metmuseum.org/perspectives/articles/2021/9/david-lavoisier-conservation. Accessed 26

    Oct. 2021.

Pigs to The Rescue!

     

    Over one hundred thousand people within the United States are on the national transplant waiting list desperately in need of a kidney. With this shortage comes about twelve deaths each day. Scientists and doctors have been trying to find out an ethical and effective way to solve this organ shortage. As of October 22, 2021, surgeons in New York City have successfully attached a pig kidney to a human that wasn’t immediately rejected by the host human. This is a huge step in modern medicine to help those who die waiting for an organ they need. This article was chosen because I signed up to be an organ donor when I got my license and believe that other people should have the chance at a second life. 

According to Science News, the article titled, “What does the first successful test of a pig-to-human kidney transplant mean?” walks the reader through the scientific and moral considerations that come with this medical breakthrough (Lambert). The process of xenotransplantation describes any procedure that involves transplantation into a human from a nonhuman source (Center for Biologics Evaluation and Research). Pigs were chosen due to how anatomically similar their organs are to humans as they have all the same thoracic and abdominal organs. They also are able to be bred in a highly controlled manner, which is important if mass production of these organs will be necessary in the near future. 

The immediate reaction that occurs following a xenotransplantation is called a hyperacute rejection. It can be described as the most severe and violent immunological reaction that occurs within the first 24 hours that results in loss of function and death of the organ (Hyperacute graft rejection). In recent years, scientists have discovered that this aggressive immune response is brought on by antibodies that detect a specific sugar molecule that dots pig blood vessels, called alpha-galactose or alpha-gal for short. This sugar molecule is also responsible for some allergic reactions to red meat. Scientists figured out how to disable the pig gene that is responsible for producing this sugar in the early 2000s but only recently have produced successful results.  

Figure 1: Structure of Alpha-1, 3-galactose

Alpha-1, 3-galactose is a carbohydrate found in most mammalian membranes except for humans and primates. While there have been some known breakthroughs when it comes to Alpha-gal syndrome (AGS), the mechanism of action for alpha-gal is still unclear and requires further research. It has been found that a bacterial alpha-galactosidase efficiently can remove linear alpha-gal ends from target molecules.

Figure 2: Stepwise process of xenotransplantation

The FDA has also recently approved altering the gene that produces alpha-gal for those who can’t eat red meat to produce a new “breed” of GalSafe pigs (Commissioner). These pigs are created by modifying the target gene (GLA) by eliminating gene expression in a pig embryo. This modified embryo is then implanted inside the surrogate sow who will deliver piglets with modified immune systems more compatible with humans. When the pig kidney is removed from the adult swine, the pig’s thymus is also removed with it and attached before attaching to the host human. This is an important step because the thymus gland can help educate the human’s immune system to recognize the kidney as part of the body. Lastly, the thymus-kidney system is surgically connected to the organ recipient on their thigh so that the doctors can oversee the kidney function outside of the body.

The ethical considerations when it comes to operating on humans in this manner is always going to be up for debate. The family of a woman who was pronounced brain dead but kept alive on a ventilator gave consent for this procedure to take place. The woman wanted to be an organ donor but in the state that she was in, was unable to donate her organs. The family believed that she would have approved of possibly giving the gift of humanity to other people in another way. The doctors attached a pig kidney with the absence of the alpha-gal sugar as well as its thymus gland to the woman and monitored normal kidney function. The kidney produced urine and showed other signs of normal functioning for 54 hours before the procedure was terminated due to guidance provided by ethics reviewers.

Sources

Center for Biologics Evaluation and Research. (2021, March 3). Xenotransplantation. U.S. Food and Drug Administration. Retrieved October 26, 2021, from https://www.fda.gov/vaccines-blood-biologics/xenotransplantation#:~:text=Xenotransplantation%2 0is%20any%20procedure%20that,nonhuman%20animal%20cells%2C%20tissues%20or. Commissioner, O. of the. (n.d.). FDA approves first-of-its-kind intentional genomic alteration in line of domestic pigs for both human food, potential therapeutic uses. U.S. Food and Drug Administration. Retrieved October 26, 2021, from https://www.fda.gov/news-events/press-announcements/fda-approves-first-its-kind-intentional-geno mic-alteration-line-domestic-pigs-both-human-food. Hyperacute graft rejection. Hyperacute Graft Rejection - an overview | ScienceDirect Topics. (2014). Retrieved October 26, 2021, from https://www.sciencedirect.com/topics/medicine-and-dentistry/hyperacute-graft-rejection#:~:text=H yperacute%20rejection%20refers%20to%20the,within%20a%20period%20of%20hours. Lambert, J. (2021, October 22). What does the first successful test of a pig-to-human kidney transplant mean? Science News. Retrieved October 26, 2021, from https://www.sciencenews.org/article/xenotransplantation-pig-human-kidney-transplant.