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SCIENTIA The Future of Space Exploration: Landing on Venus or Europa Tia
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Underwater Soft Robot Developed to Withstand Crushing Pressures
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Heather
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Star Twins
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Amélie
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The Use of Behavioural Genetic Evidence in Court Charlotte
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Is There a General Connection between Obesity and Genetics? Tash
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Stem Cells and Miscarriage: What is the Correlation? Emily
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Ice Variants: How Pressure and Temperature Alter the Crystalline Structure of Water Elizabeth
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Complex Chemical Evolution
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Tia
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Stabilising Vaccines Through Silica Coats
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Jyotika
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PHYSICS The Future of Space Exploration: Landing on Venus or Europa Tia The planet Venus and Jupiter’s moon Europa are both full of possibilities and contain an exciting host of potential discoveries if scientists can find a way to land on their surface. There is no question as to why scientists are striving to reach this goal: both planets have a great possibility of life. Venus contains the gas, phosphine, that could exist due to tiny lifeforms, and Europa is covered in a surface of water ice, a key variable for life to be sustained.[1][2] In order to uncover the depths of knowledge and peculiar discoveries these celestial bodies have to offer, we must land on them, but this poses the largest challenge. In the 1970s and 1980s, the Soviets attempted to land spacecraft on Venus, however, these attempts lasted no more than one or two hours. This is a result of the exceptionally high pressures, temperatures and acidic atmosphere that caused the spacecraft to either melt, corrode, or be crushed.[4] However, these spacecraft were still able to provide us with minimal data on Venus before their destruction. Attempts at landing on Europa were equally challenging, with parts of its surface shaped like blades of ice, not to mention the relentless pummelling of radiation from Jupiter.[5] So, what mechanisms have we created so far that could help us on our missions to these satellites? There have been studies and investigations into what would be able to handle the harsh conditions of Venus. Any lander on Venus would need an intelligent navigation system to pick the best spots to steer. However, they would not be able to use conventional rocket engines, so it has been proposed that the lander could use fans to push itself around. Additionally, a new navigation software would need to be developed since Venus’s dense atmosphere scatters light in a unique way that cannot be comprehended by today’s technology.[3] Any lander on Europa would use a sky crane technique, similar to the landing of the most recent Mars Perseverance Rover, since Europa has no air to lur the surface or break rockets. Currently, Europa, as captured by a passing satellite little is known about the surface of this moon, therefore, another mission - the Europa Clipper - has been developed in order to take high resolution images which can help scientists learn more about the ground conditions. In addition, scientists will also simulate ices with different chemical compositions in vacuum chambers, and will drop dummy landers from cranes to test durability in order to ensure a successful landing.[3] How long until we can reach these bodies in space? Within the next 20 years over 15 landing missions have been proposed, and a few are under development.[6] Though developments for Europa are much further behind, there is still a conceptual mission in development. So, within the next generation’s lifetimes, we may have touched down on a new planet in our solar system, or even a new moon, presenting countless opportunities to grow and develop our understandings of other celestial bodies out there. Sources:
An artist’s impression of a rover on Venus
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PHYSICS https://www.theverge.com/21438514/venus-future-exploration-spacecraft-flagship-missions-nasaphosphine-detection [1]
[2]
https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/
[3] https://www.sciencenews.org/article/nasa-venus-europa-landing-terrain-future-spacecraft [4] https://www.sciencenewsforstudents.org/article/heres-why-venus-so-unwelcoming [5]
https://www.theverge.com/2018/10/8/17948510/jupiter-moon-europa-nasa-clipper-lander-penitentes
[6]
https://en.wikipedia.org/wiki/List_of_missions_to_Venus
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PHYSICS Underwater Soft Robot Developed to Withstand Crushing Pressures Heather Over 80 percent of our oceans are still unexplored. However, our limited knowledge is enough to show us their importance in the workings of our planet. The ocean produces over half of the world’s oxygen and absorbs 50 times more carbon dioxide than our atmosphere through photosynthesis of phytoplankton, kelp and algal plankton. Exploration of deep-sea trenches has shown that they are teeming with microbial life, suggesting that these trenches play a significant role in the Earth’s carbon cycle. Further exploration will be able to provide more insight into the complicated systems which run our planet and the ever-looming question: where did we come from? However, the overriding problem of the high pressure within these trenches remains. So far, we have overcome the increasing pressure of deep-sea exploration by reinforcing submersibles with rigid metal frames to stop them from crumpling. While useful, this method of withstanding pressure makes the vessels increasingly bulky and cumbersome. This led roboticist Guorui Li of Zhejiang University in Hangzhou, China to develop a machine inspired by the deep-sea snail fish. What this fish lacks in beauty, it makes up for in its extremely well adapted body to life in the Marina trench. The fish has soft bones, and its skull is not completely fused together. This allows the pressure on the skull to equalize, enabling it to withstand high pressures. Li and his team replicated the anatomy of the deepsea snail fish to make his robot. By distributing the electronics of the robot farther apart and encasing them in soft silicone to keep them from touching they were able to prevent the electronic components from scraping and damaging one another under the pressure. They further designed a soft body which partially resembles the snailfish and is filled with a synthesized version of the water goo inside the fish’s body, adding to robot’s buoyancy and helping it to swim more efficiently. They even created artificial muscles which flap the fins of the fish.
The design of the new soft robot (left) was inspired by the deep-sea snailfish (illustrated, right)
The team performed a series of tests on their prototype. First, the robot swam freely at 70 meters deep in a lake, then at about 3,200 metres deep in the South China Sea. The robot was then tested at the bottom of the Challenger Deep, however in this trial it was held by the extendable arm of a deep-sea lander. All these results are extremely promising for the future of deep-water exploration and research, but much more research still needs to be done before these robots are deployable. Cecilia Laschi of the National University of Singapore and Marcello Calisti of the University of Lincoln in England have commented that the robotic fish swims more slowly than other underwater robots and does not yet have the power to withstand powerful underwater currents. However, it “lays the foundations” for future such robots. Biomimicry, using nature as an inspiration to innovate, is extremely common and successful in robotics. famous examples of this are SpotMini by Boston dynamics, a robot inspired by dogs and designed to manoeuvre rough terrain and CRAM by University of California, a robot that was inspired by cockroaches and their abilities to disappear down cracks that seem far too small for them to help in search and rescue missions where the site is hard to access. The success of biomimicry is Soft robot navigating the South China Sea
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PHYSICS unsurprising, since these designs have been time-tested through natural selection, resulting in organisms best adapted to their environment. By appreciating and taking inspiration from these remarkable animals around us, their million-year evolution can allow us to explore places we could never go by ourselves. Sources: https://www.sciencenews.org/article/new-soft-robot-snailfish-crushing-pressures-deep-ocean https://www.nature.com/articles/s41598-018-32757-9?WT.feed_name=subjects_soft-materials https://pubmed.ncbi.nlm.nih.gov/33658693/
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PHYSICS Star Twins Amélie New analysis by a theoretical physicist from UC Berkeley and a radio astronomer from the Smithsonian Astrophysical Observatory at Harvard suggests that all stars are born as twins – although not the identical kind. This means that our Sun most likely was too. The search for our Sun’s pair, a star dubbed Nemesis, has been ongoing for many years. It was supposed to have caused an asteroid to move into the Earth’s orbit and collide with us, killing the dinosaurs, however it has never been found.
Radio image of a triple star system forming in the Perseus cloud
This was asserted thanks to a radio survey of a giant molecular cloud in the constellation Perseus, which is filled with recently formed stars. It is 600 light years from Earth and roughly 50 light years wide. The only statistical model that could reproduce the Perseus constellation was one in which all stars initially form as wide binaries, which break apart or shrink over millions of years. These wide binaries were at least 500 astronomical units apart, therefore a wide binary companion to the Sun would have been 17x further than Neptune. We can therefore assume that it must have mixed with other stars in the Milky Way, which is why it has never been seen since.
According to first author Sarah Savoy, "Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds." This could help us to discover more about the formations of galaxies, not just stars. In 1993-1995, Pavel Kroupa carried out stellar-dynamic computations on the interaction of stars that were recently freed from their gas clouds after formation, which led him to conclude that all stars are born as binaries. However, there has been little evidence since. Stars are usually born in dense egg shapes called dense cores, which are part of huge clouds of hydrogen gas. These clouds look like black holes through a telescope, because the dust blocks light from stars both inside the cloud and behind it. However, it is possibly to probe them using radio telescopes as the clouds absorb and re-emit optical and infrared radiation at far higher wavelengths. Last year, astronomers used the Very Large Array in New Mexico to carry out a survey called VANDAM of all stars less than 4 million years old (young stars) in the Perseus cloud. Co-author Steven Stahler contacted Savoy who was part of the VANDAM team, and gathered a census on Class 0 (stars less than 500,000 years old) and Class 1 (stars between 500,000-1 million years old), combined with observations on the dense cores.
Barnard 68 cloud blocks out light, in a similar way to the Perseus cloud
They discovered that all of the wide (over 500 AU) binary systems were formed from Class 0 stars, whereas the Class 1 binary stars tended to be only 200 AU apart. The Class 0 stars were also aligned along the long axis of the dense core, but not the Class 1 stars.
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PHYSICS They continued modelling different scenarios to explain this distribution and concluded that the only way to explain this is that all stars of a similar mass to the Sun start off as wide Class 0 binaries. 6 in 10 will break apart over time, the rest will form tight binaries. Single, low-mass stars are therefore formed from the break-up of binaries. "As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis," Stahler said. "These centres of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars." Therefore, this theory implies that the dense cores convert twice as much mass into stars than we had previously believed. In the next few years, studies from the VLA and ALMA telescope in Chile and the SCUBA-2 survey in Hawaii will provide more insight into dense cores and star formation. Sources: https://phys.org/news/2017-06-evidence-stars-born-pairs.html https://cerncourier.com/a/evidence-suggests-all-stars-born-in-pairs/
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BIOLOGY The Use of Behavioural Genetic Evidence in Court Charlotte Roughly a third of Caucasian men carry an allele with a low activity of monoamine oxidase A, also known as MAOA, which is an enzyme controlling the metabolism of neurotransmitters, such as serotonin and dopamine, which influence brain function (1). It is suggested that low MAOA levels result in a person being more likely to commit a crime. Although a complete absence of MAOA function is extremely rare, the low activity MAOA version has been nicknamed the ‘warrior gene’, due to the impacts that it has on its carrier. For example, according to research published in 1993, five male members of a Dutch family were found to have no MAOA function, and this was used to explain why they displayed a low IQ and abnormal behaviour, such as impulse aggression (2). In addition, research that shows that 56% of Polynesian men have low MAOA levels, and this was used to explain problems of ‘risky’ behaviour and crime (3). However, critics of this research gave alternative explanations for the high conviction rate amongst Polynesian men, such as environmental factors.
Image showing how a low MAOA, in combination with a possible adverse environment, such as neglect or childhood abuse, can affect brain function and lead to altered behaviors.
Proof that a criminal has this MAOA version of a gene is often used in the US to avoid the punishment of the death penalty, because the combination of this genetic trait, along with trauma such as neglect or abuse during childhood, is associated with increased criminal behaviour (4). Multiple highly publicized cases have shown the possible impact of behavioral genetic evidence in court. For example, in 2007, Abdelmalek Bayout admitted to killing a man. His sentence was reduced by three years after the judge learnt that he suffered from mental illnesses as this was classed as a mitigating factor. At an appeal in 2009, a judge asked for a psychiatric report, and a molecular scientist was proved that that Bayout carried the low activity MAOA gene (5). Overall, the largest review of American court cases showed no substantial effect of behavioral genetic evidence on criminal sentencing, except a few cases in which it contributed to a jury’s decision not to enforce the death penalty.
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Graph showing the correlation between antisocial behavior, childhood maltreatment and MAOA activity.
BIOLOGY There are many problems with linking this particular gene to criminal behaviour, including the fact that a variety of behaviour is considered to be aggressive, and that the gene is too common in the male population to provide strong evidence for why certain people are more violent than others. Therefore, it is difficult to show the impact of the allele on an individual, rather than in people in general. Research is being conducted to further explore the effects of the low activity MAOA gene in more detail (6), meaning that in the future, it is likely that behavioural genetic evidence will have a very large impact in the criminal court. Sources: 1. 2. 3. 4. 5.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865459/ https://www.discovermagazine.com/the-sciences/a-violence-in-the-blood https://www.nature.com/articles/jhg201219 https://www.pnas.org/content/106/7/2118 https://www.nature.com/news/2009/091030/full/news.2009.1050.html?message=remove&s=news_ rss&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+news%2Frss%2Fmost_re cent+(NatureNews+-+Most+recent+articles) 6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865459/
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BIOLOGY Is There a General Connection between Obesity and Genetics? Tash To define obesity, or to be overweight, means having abnormal or excessive fat accumulating in the body, presenting a risk to health in many different ways. When we look at the importance of genes in the body. we know that genes give the body instructions for responding to changes in its environment - both internal and external. This means that we can immediately associate genetics with body weight and food consumption, as our body may be ‘genetically engineered’ to respond with a fast or slow metabolism, with excess weight gained from eating certain foods, and we may even have the obesity-associated gene… FTO The obesity-associated gene - what is it? It is a protein which has an amino acid sequence made to demethylate - remove a methyl group - from DNA. Studies suggest that the levels of this gene - known as the FTO gene - can decrease during fasting periods and they can increase during feeding. The variation in FTO levels result in decreased expression or activity of the gene. This might provide a signal that promotes obesity. Similarly, variants of the FTO gene risk having an obesity-triggering allele. A study focused on 38,759 Europeans aged 7 and upwards and whether they had variants of the FTO obesity risk allele. It was found that carriers of one copy of the allele weighed on average 1.2 kilograms more than people with no copies, with all other conditions kept the same. Carriers of two copies weighed 3 kilograms more. This shows how even the simplest of mutations and variations of the genetic makeup can cause life-altering shifts in one’s body, especially in obesity which can be detrimental mentally, as well as physically [1].
Variants of the FTO gene can have many affects on the body, one of which is obesity.
Bardet-Biedl Syndrome (BBS) Bardet-Biedl syndrome is a human genetic disorder that affects many body systems. It is an autosomal recessive disorder, meaning that the sufferer inherits two mutated genes, one from each parent. A sufferer of BBS will have specific proteins that can cause vision loss, varying degrees of learning disabilities, and kidney abnormalities which can make the disease fatal. Another dangerous symptom is obesity, since the disorder can disturb appetite-regulating hormones. Abnormal weight gain typically begins in the early childhood stages and can continue into the rest of the patients’ lives [2]. The issue with such a threatening aspect of having BBS is
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BIOLOGY that obesity is not just one disease - it encourages endless damage to the body. Obesity increases the risk of type 2 diabetes, hypercholesterolemia, atherosclerosis and high blood pressure. Within the UK, around 1 in 160,000 people have BBS, which adds to the worrying danger of the estimated 28% obese UK adults.[3][4] Prader-Willi Syndrome (PWS) Another genetic disorder that can prove a lifetime of struggle with obesity is Prader-Willi syndrome. PWS is caused by a loss of specific genes on chromosome 15. It starts in childhood and newborns may present with weak muscles, poor feeding and slow development. Those affected become constantly hungry, leading to obesity and type 2 diabetes. There is a noticeable physical difference since sufferers often having a narrow forehead, small hands and feet and can be short in height too, alongside the impact of obesity. Most sufferers, as adults, are unable to have children. About 74% of cases occur when part of chromosome 15 from the Facial features presented with Prader-Willi father is deleted. In another 25% of cases, the affected person Syndrome. has two copies of the maternal chromosome 15 and lacks the paternal copy. They end up with no working copies of certain genes. PWS is not generally inherited, but rather the genetic changes happen during the formation of the gametes or in early development. Unfortunately, the disease affects between 1 in 10,000 to 30,000 people worldwide. Treatment Both diseases have no cure. However, the symptoms can be managed. BBS patients can be provided with vision aids and mobility training, they can have speech therapy and special education and monitored hormone levels. It is assumed that patients can have a kidney transplant to manage BBS, but the immunosuppressants taken afterwards can contribute to obesity, making it very risky. In PWS, new-borns can be supported with feeding tubes, strict food supervision from age three, and they will often have an exercise program. Growth hormone therapy can improve outcomes too. Life expectancy is limited with PWS, as there is a 75% mortality rate for 42 year olds with the disease. This is worsened when food intake and exercise activity is not managed appropriately since weight levels can become dangerously high and there is a higher chance of having heart issues [5][6]. When their quality of life is also low, due to inability to lead a fully-independent life even as an adult, PWS patients may be impacted in all areas of their lives. BBS also gives a high mortality rate, but with the development of both genetic technology and treatments, it is hoped that life expectancy for sufferers of both diseases will improve over time. Conclusion It is readily apparent from this that obesity can affect anyone, no matter the speed of your metabolism, the amount of exercise one does, or other factors in your life. This is because the slightest genetic mutations and variations of proteins from proteins that we all have can trigger such a great effect on the body. Whilst the chances are so low for both these types of variations like seen in FTO and genetic disorders such as BBS and PWS, it is essential that we are aware of these signs, and that we know the right ways to take care of our bodies with sufficient exercise and careful monitoring of our food intake. Sources: 1. 2.
https://en.wikipedia.org/wiki/FTO_gene https://en.wikipedia.org/wiki/Bardet–Biedl_syndrome
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BIOLOGY 3. https://rarediseases.info.nih.gov/diseases/6866/bardet-biedl-syndrome 4. https://medlineplus.gov/genetics/condition/bardet-biedl-syndrome/ 5. https://en.wikipedia.org/wiki/Prader–Willi_syndrome 6. https://www.nhs.uk/conditions/prader-willi-syndrome/ 7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770999/
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BIOLOGY Stem Cells and Miscarriage: What is the Correlation? Emily A miscarriage can be defined as the loss of a pregnancy within the first 23 weeks. Around 10 to 20% of pregnant women will suffer a miscarriage [1]. Recurrent miscarriages, where a woman suffers 3 or more consecutive miscarriages, affect one in 100 women. A recent study in the University of Warwick has discovered a link between a lack of highly proliferative mesenchymal stem cells (hPMCs) in the lining of the womb and the likelihood of a woman suffering from recurrent miscarriages [2]. During the second half of the menstrual cycle, the endometrium (womb lining) responds to increased levels of progesterone by remodelling itself so it is ready for the short period of time when an embryo can be implanted. This process is called decidualisation and it depends on the differentiation of endometrial stromal cells into specialised decidual cells [3]. During this time, lots of highly proliferative mesenchymal stem cells (hPMCs) are directed to the endometrium due to their important role in aiding the endometrial remodelling as well as maintaining the placenta as explained later in this article.
Diagram showing the decidualisation process and how highly proliferative mesenchymal stem cells aid with this.
The study in Warwick aimed to find out where these hPMCs were differentiating from and how exactly they worked. In the study, tissues were taken from the lining of the womb of 183 women and analysed closely. The results showed that fewer hPMCs were found in the group of women suffering from recurrent miscarriage compared to those in the control group and these results suggest that there is a correlation between the hPMCs and recurrent miscarriage [4]. Dr Brosens, the professor who led the research at Warwick, said they had found that the “hPMCs are derived from circulating bone marrow-derived stem cells and recruited into the lining of the womb at the time of embryo implantation” [1].
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BIOLOGY Lots of hPMCs are needed in the endometrium during conception as they play a vital role in assisting the rapid growth of the placenta. With a depleted number of these stem cells, as found in women suffering from recurrent miscarriages, there are not enough cells being produced in the placenta to allow it to grow adequately and this also affects and interrupts the interaction between the lining of the uterus and the placenta which can lead to miscarriage [5]. Overall, a lack of these stem cells means that the endometrium has worse conditions to support the embryo and there is also extra stress placed on the specialised decidual cells (which could breakdown the lining and also cause miscarriage) [6]. Using information from these trials, scientists are now researching ways of preventing recurrent miscarriages through increasing the number of hPMCs in the endometrium by either physically inserting more in, or encouraging the differentiation of more hPMCs. There is a trial currently happening that is investigating the use of Sitagliptin, a drug used for diabetes, in preventing miscarriage. When an enzyme, called DPP4, is too active, it can stop the stem cells from being directed to the endometrium which could explain why there is a lack of hPMCs in the endometrium in certain women. The sitagliptin drug acts as a DPP4 inhibitor and therefore allows the stem cells to reach the endometrium as normal and perhaps prevent miscarriage [7]. An initial trial for this drug went ahead at the start of 2020 where 38 women suffering from recurrent miscarriages were given the sitagliptin drug or a placebo. The results showed that the number of stem cells in the endometrium increased by 68% after taking the sitagliptin whilst there was no increase with the placebo [7]. The number of stressed decidual cells also decreased by 50%. A further clinical trial will be happening for this drug over the course of the next year and will hopefully be able to prevent thousands of recurrent miscarriages.
Results from the sitagliptin trial showing that there was a bigger change in the CFU count when using the Sitagliptin compared to barely any change when using the placebo. A CFU count shows the ability of the stem cells to proliferate and differentiate in this sample.
Overall, this information from the Warwick study has provided crucial information about how miscarriages are caused and has therefore prompted the research and further trials of treatments that will help to prevent recurrent miscarriages.
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BIOLOGY Sources : 1.
https://www.mayoclinic.org/diseases-conditions/pregnancy-loss-miscarriage/symptomscauses/syc-20354298
2.
https://warwick.ac.uk/newsandevents/pressreleases/stem_cell_depletion
3. https://stemcellsjournals.onlinelibrary.wiley.com/doi/full/10.1002/stem.3367 4. https://www.sciencedaily.com/releases/2016/03/160307211055.htm 5. https://sydneynewstoday.com/diabetes-drugs-may-help-women-with-repeated-miscarriagesstudies-miscarriage/110800/ 6. https://www.thepharmaletter.com/article/diabetes-drug-could-lead-to-new-treatment-forrecurrent-miscarriage 7. https://www.tommys.org/research/research-topics/miscarriage-research/can-sitagliptin-helpincrease-stem-cells-wombs-women-who-have-suffered-recurrent-miscarriages
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CHEMISTRY Ice Variants: How Pressure and Temperature Alter the Crystalline Structure of Water Elizabeth It is a much beloved factoid that water expands upon freezing. Indeed ‘normal’ ice on earth has a volume about 9% greater than that of liquid water [1] and the secret to the low density of ice lies in its crystalline structure. Further, this crystalline structure is controlled by the pressure and temperature of the surrounding environment, which produce different types of ices. To date, research has identified and produced 19 different ice polymorphs [2]. Indeed, we can be confident that water’s bizarre freezing behaviour is responsible for the nature of our world today; if the ice that formed at earth’s pressure and temperature conditions were denser it would sink, clogging bodies of water into solid blocks of ice [1]. Crystalline structures of ice on earth On earth, the dominant ice polymorph which constitutes everything from arctic icebergs to the ice cubes in soft drinks is the arbitrarily named ’Ice I’ [5]. Ice I is therefore produced at atmospheric pressure and around 0 degrees Celsius. When the ice is freezing in these conditions, strangely the H20 molecules do not stop moving as whole units. Instead, intermolecular interactions lead to the oxygen atoms forming a hexagonal crystalline structure whilst the hydrogen atoms are randomly oriented [4]. This open hexagonal structure with such large gaps between the atoms is what causes Ice I molecular structure
ice to be lower density than water [6]. In Ice I, each oxygen atom is loosely surrounded by 4 hydrogen atoms. 2 are covalently bonded to the oxygen, and two form a hydrogen bond with the oxygen atom’s unshared electron pairs [2].
Ice variants; crystalline structure and hydrogen ordering Under different pressure and temperature conditions, ice polymorphs will form a dazzling array of different crystalline structures. The behaviour of hydrogen atoms in ices also varies. An ice phase diagram, shown below, demonstrates the pressure and temperature rates across which different ice polymorphs exist. Indeed, Ice 1 –despite its ubiquity on earth- is only rarely found in space. Ices are also described as being either ‘hydrogen ordered’ or ‘hydrogen disordered’, depending on the behaviour of their hydrogen atoms. Returning to Ice I, the hydrogen atoms do An ice phase diagram for ices I-XVII not participate in the crystalline structure and are randomly oriented around their oxygen. This kind of ‘disordered’ ice can deform under pressure, hence flowing glaciers of Ice I. By contrast ‘hydrogen ordered’ ices have hydrogen atoms in crystalline structures as well, with the effect that ices are more brittle [5].
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CHEMISTRY Matching up some ice phases to their crystalline structures.
Ice II and IV = rhombohedral Ice III, VI, IX, XII, XV, XIC = tetragonal Ice V, XIII = monoclinic Ice VII and VIII =cubic Ice IX and XIV = orthorhombic [3]
Investigating ice polymorphs and their structures Many different ice polymorphs can be formed in the lab by either by cooling water under high pressure or by applying pressure and cooling to an earlier ice polymorph [11]. A good example is Ice VI which is a hydrogen disordered ice polymorph. Ice VI has two ordered forms –Ice XV and Ice XIX- both of which are hydrogenordered ices, each with their hydrogen atoms aligned in completely different patterns [5]. Ice XV was first produced at Innsbruck university about 10 years ago [7], more recently Ice XIX was first made in a lab at Innsbruck University 3 years ago. To achieve this, the team slowed the cooling process for Ice XV, reduced the temperature to about –200 degrees Celsius and increased the pressure to 2 gigapascals. Now they had to describe the crystalline structure. This is done using neutron diffraction, whereby a stream of neutrons is fired at the substance. The resultant diffraction pattern allows scientists to painstakingly deduce the crystal structure of an ice polymorph [5]. The process usually requires replacing the water used in the sample with ‘heavy water’. In ‘heavy water’, the water molecules have deuterium which is an isotope of hydrogen containing an extra neutron [5][7]. However, this was impractical for the experiment since heavy water freezes too slowly. Luckily, the team found that dousing the heavy water with some light water minimised disruption to ice-freezing process and meant it was still suitable for neutron diffraction [5][7]. The fact that both Ice XV and XIX come from same ‘parent’ ice means that scientists can now observe the transition process between two ice forms in one experiment. It is hoped that this will help improve our understanding of the hydrogen bond; hydrogen bonds are imperfectly understood but key in different ice polymorph structures [7]. Superionic water or Ice XVIII and the ice giants Uranus and Neptune As one might expect, giving the massive variations of temperature and pressure across the universe and subsequent incidence of different ice polymorphs, the study of ice polymorphs is valuable to astrophysics because it helps explain the behaviour of icy structures of celestial bodies [5][7]. For example, Ice VII, (which has a cubic crystalline structure and forms at 30,000 atm) is hypothesized to constitute the ocean floors of Europa, (the smallest of Jupiter's Galilean moons) [12] Another variant, Ice XVIII has also received much attention due to its potential role in the icy cores of Uranus and Neptune. Uranus and Neptune have been found to have magnetic fields which differ greatly to that of earth. One hypothesis suggests that super ionic water could play a role. [8]. Ice XVIII or ‘superionic water’ is a phase 19
CHEMISTRY that exists at very high temperatures and pressures. In it the water molecules ionise so that the oxygen atoms crystallize into a regular lattice and hydrogen atoms float freely. This means that under the effect of an electrical current the hydrogen ions (really just protons) can freely move to carry current [9].
Left: diagram to show oxygen ions (red) in a lattice and the diffusing protons (white) Right: Under the influence of an electrical field, the protons/H+ ions travel towards the anode [9]
Returning to our gas giants Uranus and Neptune. On earth, iron in the planet’s iron core flows in such a way that the negatively charged electrons create earth’s magnetic field. However gaseous Uranus and Neptune of course lack this ferromagnetic core, yet also display magnetic fields. Therefore, it is hypothesised that the flow of protons in superionic ice instead acts to create their magnetic fields [10]. Sources: [1] https://www.sciencealert.com/water-unique-properties-tetrahedral-molecule-arrangement [2] https://www.britannica.com/science/water/Structures-of-ice. [3] https://www.lpi.usra.edu/meetings/scssi2008/pdf/9014.pdf [4]https://www.reference.com/science/happens-water-freezes-644a34973e18fc85 [5]https://www.livescience.com/exotic-ice-19-discovered.html [6] http://hyperphysics.phy-astr.gsu.edu/hbase/Chemical/waterdens.html. [7] https://www.sciencedaily.com/releases/2021/02/210218094516.htm [8] https://www.chemistryworld.com/news/glimpse-of-waters-superionic-state-may-explain-icy-giantsoddities/3008626.article#/ [9] https://www.nature.com/articles/s41586-019-1114-6 [10] https://www.apexmagnets.com/news-how-tos/superionic-water/ [11] https://www.nature.com/articles/19480 [12] https://www.sciencedaily.com/releases/2007/05/070516151053.htm
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CHEMISTRY Complex Chemical Evolution Tia Chemical evolution Chemical evolution describes the transition of molecules incapable of reproduction to living systems [6]. Chemical structures typically evolve towards increasing simplicity and thus efficiency of replication, as demonstrated by Spiegelman’s monster [1]. However, chemical molecules must possess the capacity to evolve into structures able to reproduce and therefore increase in complexity [7]. Natural events such as the rise and fall of tides cyclically produce new molecules which evolve through interaction with their environment [7]. One example of chemical evolution involves the formation of complex organic molecules in the absence of living cells. In underground chambers heated by magma, carbon monoxide and hydrogen react with minerals found in the Earth’s crust to form fatty acids and other molecules [6]. As more of these molecules are produced, pressure increases and the molecules drift into pools of water. Water molecules repel the hydrophobic tails and are attracted to the hydrophilic oxygen heads. This means that when concentrations of suspended fatty acid are high enough, they self-assemble into a stable spherical structure with phosphate heads facing outwards.
Eventually through formations of several new structures, a hollow structure akin to a living membrane can form. These are able to enclose their own environment where molecules can react. While fatty acid membranes cannot self-replicate and therefore are non-living, this instance of chemical evolution suggests that some molecules could give rise to systems capable of reproduction [6]. The RNA world hypothesis On a fundamental level, living creatures reproduce and evolve via use of genes and enzymes [1]. The RNA world hypothesis posits one explanation for the origins of live systems with self-replicating RNA molecules as the precursors to live systems. RNA molecules may have been initially formed from cyclical chemical reactions in tide pools and hot springs [5]. The structure of an RNA molecule lends itself to both the ability to store and access genetic information like its’ molecular cousin DNA as well as the ability to catalyse chemical reaction [2]. 21
CHEMISTRY The single helix structure of an RNA molecule allows it to fold into ribozymes able to catalyse self-replication. The double helix structure of DNA prevents formation of enzyme-like structures while proteins cannot store genetic information. Spiegelman's monster and other experiments Sol Spiegelman’s experiments form the foundation of the RNA world hypothesis by demonstrating selfreplicating and evolutionary abilities of RNA [1]. One of his experiments saw bacteriophage RNA and RNA replicase suspended in water containing high concentrations of free nucleotides. RNA and RNA replicase alone are non-living but were able to replicate in the solution [4]. The number of free nucleotides became the limiting factor, simulating competition. RNA strands which had replicated in the first test tube were selected and added to another solution containing free nucleotides and replicase. The RNA exponentially replicating during the initial growth period were then selected. This was iterated 74 times in following experiments where the fastest replicating RNA were transferred to each subsequent tube [4]. Typically, bacteriophages infect bacterial cells to replicate their RNA genome and form daughter cells. The bacteriophages in this experiment did not require genes coding for a protein to break into the bacterial cell envelope nor did they require a protein shell to protect its genome. Molecules were optimised through evolution with the singular goal of replication as efficiently as possible leading to the formation of “Spiegelman’s monster”. The initial RNA strand was 3300 nucleotides in length and had truncated to a mean of 550 nucleotides [4]. Shorter mutants which could replicate 15 times as fast as the original RNA sequence rendered the original molecule extinct [4]. In consequent tests, RNA was suspended in a solution containing the toxin ethidium bromide and molecules evolved against this [1]. Another experiment produced random RNA chains which some were found to be able to synthesise nucleotides with limited efficiency. The chains were selected and polymerase chain reaction (PCR) was used to replicate them with slight random mutations. Following 10 rounds of PCR and selection, highly efficient ribozymes evolved [3]. The structure of a ribozyme is a folded RNA chain with regions of self-base pairing and other outward facing bases. The latter can catalyse specific chemical reactions determined by a specific shape which is determined by its sequence. Ribozymes are formed when placed in cool water suitable for base pairing but without enough adequate free nucleotides for the replication process [5]. These may have possessed the ability to replicate. Gene mutations may alter the function of ribozymes leading to gradual evolution. Limitations There are limits to applying the principals of Spiegelman’s monster in practice because RNA molecules would not have been able to replicate without the presence of replicase enzyme. Alternative theories to the RNA world hypothesis such as the proto-RNA hypothesis are being investigated. Proto-RNAs may have been the predecessor to RNA molecules. One set of proto-RNAs involves the pyrimidine compound triaminopyrimidine (TAP) and cyanuric acid (CA). [3] When modified TAP (TAPAS) and CA were suspended in water, they were able to self-assemble into ring-like structures called rosettes which then formed long chains of genes [3]. Overcoming Spiegelman’s monster
One experiment utilised fibre formed from self-replicating rings. The size of rings in each stack was kept consistent [1]. The system was adjusted so that rings of 2 sizes were created containing either 3 or 6 building blocks. As expected, larger rings replicated slower than fibre with smaller rings. However, larger and thus more 22
CHEMISTRY complex rings were more resistant to break down in the introduction of compound which breaks up rings inside fibres. They dominated despite replicating slower [4]. Fibre formed from rings of 6 building blocks were better catalysts for the retro-aldol reaction than fibres made from rings with 3 blocks [1]. This is one example of a difference in complexity however the reaction cannot act as a defence mechanism. Enhanced complexity protects fibres from destruction by shielding sulphur-sulphur bonds which link building blocks into rings [1]. It is necessary to explore complexity through a system able to balance replication and destruction. This is A life cycle of complex and more simple because both unlimited and little variation make it difficult to molecules able to self-replicate establish patterns in competitive assets. Further experiments may look towards using more than one type of building block [1]. This system demonstrates how complexity in molecules may be favoured and thus supports the idea that complex molecules arise from simple molecules. Sources: [1]https://www.sciencedaily.com/releases/2021/03/210317141453.htm [2] world
https://www.khanacademy.org/science/ap-biology/natural-selection/origins-of-life-on-earth/a/rna-
[3] https://www.wired.com/2013/02/proto-rna/ [4] https://www.youtube.com/watch?v=qbawTxePfvs [5] https://www.statedclearly.com/videos/rna-world/ [6] https://www.statedclearly.com/videos/what-is-chemical-evolution/ [7] https://www.sciencedirect.com/science/article/pii/S1674987117301305
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CHEMISTRY Stabilising Vaccines Through Silica Coats Jyotika With the COVID-19 pandemic, and the recent Ebola virus outbreak, vaccine transport and storage are becoming ever more important, and silica coats could provide the answer as to how vaccines could be more easily and efficiently stored and transported to low-income and less developed countries. With collaboration from the University of Newcastle, researchers at the University of Bath led by Asel Sartbaeva have discovered a new method of transporting vaccines, by coating the protein molecules in a silica cage. [5] Why is it necessary? According to World Health Organisation statistics, in 2019, of the children under the age of one across the world, almost 20 million did not receive basic vaccines, something largely due to inaccessibility and unsuitable conditions for storage and transport in low-income countries. [4] Furthermore, up to half of all vaccine doses become degraded due to thermal instability and are discarded before use. [5] As many vaccines and medicines contain proteins, they degrade easily due to protein unfolding in denaturation, and thus must be stored in the "cold chain", refrigeration at 2 to 8°C across transport and Ultra-cold freezers for COVID-19 vaccines storage, which can be very costly. Silica coats could help stabilise vaccines to decreases chances of degradation and make them more resistant to temperature changes. Other similar processes to improve the thermal stability of vaccine have been attempted, but unlike silica encapsulation, many require freeze-drying, which half of all vaccines do not survive. [6][7] How are the coats formed? Silica coats are formed in a process known as the sol-gel process, a long chemical process involving, by step: hydrolysis and polycondensation (these are the main two reactions involved), gelation, ageing, drying, densification, and crystallisation. [3][8] In this case, the precursor solution (as shown in figure 2) is the silica precursor, tetraethyl orthosilicate, which is hydrolysed in the sol-gel process to form orthosilicic acid. This is then broken down and combined with a specific target protein that catalyses the reaction by attracting silica that has been added. This acid can then form a tight mesh around the protein molecules, pulling silica into clusters around the protein in the process, which in turn creates a silica coat around the protein molecules, resulting in a silica powder enriched with the protein. [3][7]
The Sol-gel process
How does the coat protect the protein? [3]
! It protects the secondary and tertiary structure of the protein, preventing denaturation. ! This allows the protein molecules to endure more extreme temperatures than that of typical vaccines. The protein has shown to remain intact even when powders are heated to boiling point. What success has there been?
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CHEMISTRY In 2020, the team took used the method on the tetanus toxin C fragment (TTCF), a component of the diphtheria, tetanus, and pertussis vaccine, that had previously been prone to problems in transportation. With the silica casing, the powder was able to be stored at room temperature without special equipment for a month, with the powder also proven to have the same immune response as TTCF without the coat. [3] Future implications Experimental data completed by Sartbaeva's team suggests that this process can increase the shelf life of vaccines for up to four years and still function as normal, but they hope that they can increase this to as many as 15 years. The main challenge lies with which vaccines can be effectively encapsulated, as out of the 14 targets of the team, one proved very difficult. However, if proved successful with a variety of vaccines, this method could prove vital in rolling out vaccines to areas that currently cannot store or receive them, with the team currently looking at how the process could be used in the COVID-19 vaccine rollout. [3] Sources: [1] https://www.ft.com/content/0207755e-1bc8-4b46-bc25-1d89f4f9b6f5 [2] https://www.sciencedirect.com/topics/materials-science/sol-gel [3] https://www.chemistryworld.com/news/university-teams-silica-coats-stop-vaccines-spoiling-at-roomtemperature/4013348.article#/ [4] https://www.who.int/news-room/fact-sheets/detail/immunization-coverage [5] https://www.bath.ac.uk/announcements/ground-breaking-research-makes-childhood-vaccines-safe-inall-temperatures/ [6] https://www.bath.ac.uk/announcements/tiny-cages-to-keep-vaccine-supplies-safe/ [7] https://www.nature.com/articles/srep46568 [8] https://www.sciencedirect.com/topics/chemistry/sol-gel-process
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