• New Site Launched (Again!)

    Bratislava New Year Fireworks

    Having long been dissatisfied with the usability of the website-builder Wix, and having recently been informed that they intended to increase the hosting price by 64%, I have opted to abandon their service and migrate the content to WordPress, alongside my personal blog and Paull Holme Tower.

    There is a little less room for customisation here – hence no more colour-coding of the academic faculties – but that is more than compensated by being easier to manage and less prone to glitches.

    All the individual homework articles are now treated as posts rather than pages, and are searchable through the normal system of categories rather than needing bespoke menus to be created. The separate blog announcements for each new article have been abolished. Comment sections are available on each individual post – though subject to moderation, of course.

  • The 1995 Nobel Chemistry Prize

    Hole in the Ozone Layer Over Antarctica - GPN-2002-000117

    Who won the prize, and why is it important?

    The prize was shared equally between three winners: Paul J. Crutzen, F. Sherwood Rowland and Mario J. Molina. Their field of expertise was atmospheric chemistry, specifically their discoveries about the ozone layer.

    Crutzen, 61, was born in Amsterdam. His school years were disrupted by the Wehrmacht invasion of the Netherlands, but he was able to advance through his education and went to Stockholm University to work as a computer programmer. He studied meteorology, learning about the carbon cycle, cloud physics and acid rain.

    In the 1970s he moved to researching stratospheric ozone, a field which had not been explored much before.

    Molina spent his childhood in Mexico City, then had his higher education in Europe. In 1968 he began graduate studies into physical chemistry at the University of California. He completed a PhD in 1972 and began to work under Rowland studying CFCs. Chlorofluorocarbons are inert chemicals which at the time were released in a lot of industrial gases. Molina and Rowland developed the “CFC-ozone depletion theory”.

    Rowland, 68, was born to an academic family in Delaware. He skipped some academic years and had his final year of university before this eighteenth birthday. In 1973 he started work on atmospheric chemistry, following discoveries by Jim Lovelock. He worked with Molina on the ozone layer, which by 1974 had become a major issue of public concern.

    The ozone layer is a section of the Earth’s atmosphere which contains the largest quantities of Ozone gas (O3). It is between 15km and 50km from the surface. Were this layer absent, plant and animal life could not evolve on Earth. Ozone absorbs the ultraviolet radiation from the sun, so that most of it does not reach ground level.

    Research by the prize winners revealed that the layer was being damaged by emissions of man-made chlorofluorocarbons into the atmosphere. CFCs were at the time used widely in industry, having been chosen because their inertness and non-toxicity were thought to have made them environmentally harmless. In fact, as it was later realised, CFCs were rising to a similar height as the ozone layer then being blasted by ultraviolet radiation – which split up the molecules, releasing chlorine gas atoms.

    In 1970 Crutzen had shown that nitrogen oxide and nitrogen dioxide (formed by the decay of N2O) can also cause a catalytic reaction with O3. This effect accelerates the ozone layer’s deterioration. Combined with that of Harold Johnston, Crutzen’s work sparked fears that the rise of supersonic air travel would destroy the ozone layer, because the aeroplanes would fly at altitudes of around 20km (ie. Within the layer) and release nitrogen oxides among their waste gases.

    In 1974, Rowland and Molina showed that CFCs in spray cans also damaged the atmosphere. There were restrictions placed upon their use until 1985, when a hole in the ozone layer was discovered over the south pole. In 1987 the United Nations introduced protocols to protect the ozone layer and by 1996 the offending gases were entirely outlawed. The 1995 prize rewards the contributions of Molina, Crutzen and “Sherry” to our understanding of the ozone layer, without which there might by now have been permanent damage done.

  • Fluorine


    A summary of research into a select halogen.

    Fluorine is the lightest of the halogens. It is the most reactive element on the periodic table, and the most electronegative (3.98). It melts at 53.53 and boils at 85.01K, so is normally encountered as a pale yellow-green gas. A fluorine atom has nine protons, ten neutrons and the electron arrangement (1s2 2s2 2p5). Normal fluorine molecules are diatomic (F2), but the element is so dangerously reactive that it is more commonly found as fluoride (F-) ions.

    Fluoride is considered an essential chemical in the human body (though the quantities are very small). Overall, the average body contains 3 to 6 grams of fluoride, and takes in 0.3 to 3 miligrams per day. F- makes up 200 to 1200 parts per million, and 0.5 mgL-1 of blood. Fluoride is highly beneficial to teeth, because it converts calcium phosphate into the harder fluoroapatite. For this reason F- is contained by many toothpastes and some countries add it to public water supplies. In medicine, fluoroquinolanes are used to tackle infections which other antibiotics cannot, such as gonorrhea. They work by stopping the coiling of bacterial DNA so to prevent pathogens from multiplying.

    For a long time fluoride salts were used in frosted glass and welding, however it was not mass produced until the Second World War when it was used in nuclear energy projects (fluorine gas is used to make uranium hexafluoride which can separate uranium-235 from its less useful isotopes). Various fluorine-based minerals are in industrial use today. Fluorite (or fluorspar) is widely used in the smelting and refining of metals. Around six million tonnes are produced globally each year (mostly in China). F2 gas is widely used for the plasma etching process, used for flat-screen televisions and semiconductors.

    In 1802, fluoride was discovered in bones, teeth and ivory. By the mid-nineteenth century, it was found in hair, saliva, urine, blood and brine, but it was not until 1886 that fluorine could be isolated. The achievement was that of French scientist Henri Moissan, who electrolysed potassium bifluoride in Paris.

    Fluorine is the 13th most common element in the Earth’s crust, making up roughly 950 parts per million. Large quantities are released into the atmosphere by volcanic eruptions. Various fluoride compounds are also entitled industrially, raising concerns about the environmental impact. The use of chlorofluorocarbons in aerosols, for instance, was banned to stop damage being done to the ozone layer.

    While fluoride is a valuable tool in medicine, excess can itself cause health problems. If F- hardens the bones too much, it can result in skeletal deformation. Pure fluorine gas, even in 1/1000 concentrations, is fatal to inhale for a few minutes. In countries where water has high fluoride levels, fluorosis is a major problem which can affect millions.

    Sources: chemicalelement.com; terpconnect.umd.edu; rsc.org; brittannica.com; “Nature’s Building Blocks” by John Emsley.

  • Quark Theory

    Murray Gell-Mann - World Economic Forum Annual Meeting 2012 (cropped)

    Researching the Quark Model, including Gell-Mann and Zweig

    For an organism’s diet to be “balanced”, it must include the correct proportions of all the nutrients that are needed for that organism to function and grow. For humans this means lipids and carbohydrates for energy, mineral salts for growth, vitamins to prevent disease and protein to repair damaged tissues, with water to help transport them all around the body.

    Quarks are elementary particles of which all hadrons are composed. They are not directly observable alone, so everything known about them is taken from experimentation with hadrons.

    Quarks are unique in that they are the only particles which have fractional rather than integral charges, and the only elementary particles to experience all four of the fundamental forces (the strong nuclear force, the weak nuclear force, electromagnetism and gravity).

    Quarks come in six types (or “flavours”): the up quark, the down quark, the charm quark, the strange quark, the top quark and the bottom quark. All quarks have the same “spin” of ½ but they have different charges and masses.

    Up: +2/3, 2.5 MeV

    Down: -1/3, 4.95 MeV

    Charm: +2/3, 1270 MeV

    Strange: -1/3, 101 MeV

    Bottom: -1/3, 4.2 GeV

    Top: +2/3, 172 GeV

    Baryons (which include nucleons) are each made up of the three quarks. A proton, for instance, is made of two up quarks and one down quark, giving it a charge of +1. Each meson is made of one quark and one antiquark (each quark has a corresponding antiquark, with the same mass but opposite charge).

    Up and down quarks are the most common in the universe, because their lower mass gives them stability. The much heavier top, bottom, charm and strange quarks are less stable and hence particle decay leads them to change rapidly into the up and down flavours.

    In 1964, scientists Murray Gell-Mann and George Zweig independently proposed the Quark Model as a way of explaining the properties of particles such as protons and neutrons, though it did not become established as fact until 1977. The physical evidence for their existence came from deep inelastic scattering experiments. In 1968 the discovery of the top quark was not until 1965.

    Sources: wikipedia.org; hyperphysics.phy-astr.gsu.edu; universetoday.com

  • The Structure of Lactose

    Α-lactose (Mills projection)

    How can the structure of lactose cause lactose intolerance in some people?

    Lactose is a disaccharide sugar, with the formula C12H12O11. It is formed when the monosaccharide sugars glucose and galactose undergo a condensation reaction together (meaning that the two molecules join together to form a large molecule).

    Lactose makes up around 5% of milk, a liquid normally fed to baby mammals. To digest this they use the enzyme lactase, which hydrolyses the β-glycosidic bond in lactose, splitting it back into glucose and galactose. Both of these monosaccharides can be absorbed through the walls of the intestine.

    The milk given to very young baby mammals is called colostrum. It is produced in smaller quantities than later milk, but with a higher concentration of the nutrient. Colostrum provides immune cells, including lymphocytes and multiple forms of immunoglobin, as well as many growth factors. The milk contains high quantities of Vitamin A, salt and proteins. It does not, however, contain much in the way of lipids, potassium and carbohydrate – all of which will appear in later milk.

    Not all milk is the same. The milk given by most mammals is largely made of water, yet seals give more than half its volume to fat. Humans have more sugary milk than that of most other animals, but a much smaller proportion of protein. The composition of the liquid is, in all cases, designed to best suit the nutritional needs of the child in accordance with their native environment.

    Lactose intolerance is a condition affecting those who cannot produce the enzyme in sufficient quantities. This is normal in most mammals, who never drink milk as adults (and to continue producing lactase persistence), but in humans the level of lactase production varies by continent (only 5% of Northern Europeans are intolerant, compared to 90% in Africa and Asia). Without lactase to break apart the large molecule, lactose remains a disaccharide. Disaccharides cannot cross the membranes of intestinal cells to be absorbed, so they cannot be digested. It then passes instead to the colon, where it is broken down into fluid (called lactose malabsorption), leading to symptoms such as abdominal bloating, nausea and diarrhoea.

  • Why didn’t the USA win the Vietnam War?

    https://upload.wikimedia.org/wikipedia/commons/thumb/f/fc/UH-1D_helicopters_in_Vietnam_1966.jpg/1280px-UH-1D_helicopters_in_Vietnam_1966.jpgAn essay of 1.5 pages including conclusion.

    By April 1973, all American soldiers had been withdrawn from the war effort in Vietnam after the US government, under pressure from public opinion, conceded that the campaign against the Viet Cong could not succeed.

    The proof of this was evident from the first exposure to the Vietnamese tactics. Prior to this conflict, the US military had little, if any, experience of Guerilla Warfare. Thus, when they attempted to engage the Viet Cong in combat, they were totally unprepared for what they encountered: The Communist-Led National Liberation Front of South Vietnam eschewed traditional fighting techniques in favour of hiding among the jungle foliage and attacking the US troops from behind. They had no military uniform, instead wearing civilian attire to blend in with the local populace, and operated from a decentralised system of hidden underground bases, allowing them to travel light, unlike the heavily-laden Americans who could not cope with the jungle’s heat. These tactics proved highly effective against the United States which, unable to defeat this frightening new enemy by tact, opted instead for brute force.

    The most common tactic of the US soldiers was “search and destroy”, meaning soldiers were ordered to slaughter everyone in sight and pillage their surroundings. Unsurprisingly, this resulted in many civilian deaths. It also led to many soldiers walking directly into Viet Cong traps. At a ground level, the Air Force planned to uncover the enemy hiding places by bombing the jungle in which they were situated. Traditional explosives failed to defeat the Viet Cong – only to kill more civilians – so use was instead made of Napalm, a sticky jelly which burned through skin, and Agent Orange, a defoliating spray which ruined 25000km² of jungle and led to widespread birth deformities. The result of this was that the Americans gained a very poor reputation among both the Vietnamese and their own peers.

    In mainland USA, support for the war was very low in the late sixties. Protesters chanted at Lyndon B. Johnson from outside the White House and the general public were regularly exposed to the horrors of the battlefield on television. Civilians were outraged at what they saw, while soldiers suffered poor morale due to the trauma of the experience. There was also the factor of expense: The taxpayer spent $400000 on each Viet Cong killed, a total cost of $108 billion, all for a war in which their own country seemed to be the aggressor. As a result, many Americans tried to avoid participation, to the effect that 600000 potential conscripts instead became “draft-dodgers”. Fearing instability, the government eventually began dialling down the USA’s role in the conflict before withdrawing altogether.

    Overall, the cause of the United States’ failure to win the war can be summed up as incompetence, inefficiency and (un)intelligence. The US attempted to fight a new kind of war with old types of tactics, and did not attempt to truly understand the situations they found themselves in before attacking with full force, believing that America was powerful enough to defeat the natives by sheer attrition, regardless of their inferior tactics. This meant there was a tremendous waste on many levels ($108bn spent, 350000 US troops killed, 4 million Vietnamese slaughtered, 82 million litres of Agent Orange dumped) and led to the US suffering civil unrest at home… all for a war which was unwanted to begin with. It was, if not all else, a great embarrassment, and so they failed to find sympathy with their own citizens, or the Vietnamese, for whom the Americans only achievement was to make the Viet Cong seem like heroes by comparison.

  • The Log Scene in “The Tempest”

    File:Angelica Kauffmann 007.jpg

    How does Shakespeare make this such a moving and dramatic moment in the play?

    The moving drama of this extract derives primarily from the fact that it features the moment at which the young leads confirm themselves as a couple. This is a “feel-good” point for the audience, and it later forms an important part of Prospero’s overall plan – uniting Milan with Naples.

    This scene is made more interesting by its subversion of the normal tropes associated with theatrical romance (including those from Shakespeare himself), in that Miranda is here shown offering to share the workload given to Ferdinand (“If you’ll sit down, I’ll bear your legs the while; pray give me that; I’ll carry it to the pile.”), rather than being the traditional passive female in awe of the strong male. The prince, of course, refuses to subject her to “such dishonour”, but Miranda is unfazed.

    Ferdinand himself also plays down his supposed magnificence (“I am, in my condition, A prince, Miranda; I do think, a king – I would not so!”), but what makes this scene so moving is that Miranda still loves him, despite both acknowledging his imperfections, and indeed Ferdinand still shows his commitment to loving Miranda (“I, beyond all limit of what else i’th’world, do love, prize, honour you.”), thereby making their relationship more meaningful than a mere “Prince Charming”-type affair.

    Of course, the audience is also reminded of the unusual circumstances of this meeting – Miranda, having been stuck on the mysterious island for well over a decade (indeed around 75% of her life) does not remember much in the way of meeting other people. She cannot really judge Ferdinand because she has no yardstick – declaring “How features are abroad, I am skilless of.”. This increases the drama of the scene as, by knowing how far out of her ordinary experience this is, we find Miranda’s reaction ever more powerful.

    Then, far away from the young couple but aware of their every move, we have Prospero himself. In his rare and brief but nonetheless powerful contributions to this scene, the magician is shown to be uneasy about finally letting his daughter go. Having already warned Miranda of Ferdinand’s obvious (to all but her) shortcomings, he now says “Poor worm, thou art infected!”, as if regarding her romantic instincts to be symptoms of a mental illness, yet importantly he does not attempt to stop their engagement – indeed he actively helps them along and cautiously encourages them. This could move the audience if correctly executed, as they know how hard it is for Prospero to give up control of his daughter and only same-species companion.

    Indeed there is a dramatic contrast played up between the two available states of affairs: keeping or releasing Miranda. Until now, Prospero has been – and still is – a powerful and authoritative wizard, with the potential for total control over his offspring. Now, however, he is allowing her not only to join another family, but in time to outrank himself (as the eventual queen consort of Naples when Alonso dies). This reinforces the dramatic weight of Prospero’s decision to renounce the supreme power which he had slowly accumulated. His final remark of “Heavens rain grace on that which breeds between’em!” indicates not only happiness on the part of his daughter, but also a willing acceptance of the changes to come.

  • Prospero in “The Tempest”

    https://upload.wikimedia.org/wikipedia/commons/5/55/Prospero_commanding_Ariel.jpgHow does Shakespeare portray Prospero in Act 5?

    The final scene of the final play sees Prospero complete his masterplan of punishing then forgiving the royal court of Naples, marrying Miranda off to Ferdinand and securing his return home. At the very end of the play, he delivers an epilogue declaring that his magical powers have been relinquished and asking the audience to release him.

    Much of this relates to Shakepeare’s own life at the time of writing: This was his last full play and he was announcing his retirement. The Duke’s penultimate speech says “Retire me to my Milan, where every third thought shall be my grave.” – which could be a reference to the bard’s advancing age and impending demise (indeed he only had around six years to live after finishing The Tempest), and the final page features him essentially asking the audience to let him end it all.

    For the in-universe aspects of Prospero’s character we see a mixture of anger, relief and exhaustion. When he has gathered the hypnotised crowd inside the magical circle, he vents his thoughts on them to their blank faces. He calls the lot of them “useless” and says their brains are “boil’d within [their] skulls”. At first it appears that he will smite them, but instead he says “I do forgive thee, unnatural though thou art.”. When talking to Sebastian he says “For you, most wicked sir… I do forgive thy rankest fault – all of them.”. The general undertone of this entire sequence is that he desires to make his prisoners aware of the suffering they have caused, but now lacks the stamina to effect a drawn out penalty.

    It could be that he is trying to force himself to hurry through and not linger on revenge – to concentrate on his true aim of getting back to Naples. It seems at other points in the play that he may have been putting off his disempowerment for quite some time. Certainly he seemed rather reluctant to give up Ariel, stating “Why that’s my dainty Ariel. I shall miss thee, but yet thou shalt have freedom.” – indicating that he has grown rather attached to the harpy, yet knows he must eventually dismiss him. Likewise, he continues to make use of his magic even as he promises to lose it. Only at the very end of the play does he finally let go.

    What we see throughout this act is an old and weary yet fulfilled Prospero, who has released his charms but also his chains, and is the better for it.

  • Milk in a Balanced Diet

    A milkmaid in Dresden pouring milk from a churn into a large mug for the dog who is yoked to the cart carrying milk churns

    To what extent does milk satisfy the requirements of a balanced diet for a newborn mammal?

    For an organism’s diet to be “balanced”, it must include the correct proportions of all the nutrients that are needed for that organism to function and grow. For humans this means lipids and carbohydrates for energy, mineral salts for growth, vitamins to prevent disease and protein to repair damaged tissues, with water to help transport them all around the body.

    As mammals tend still to be undergoing important development for a long period after birth, many are unable to digest solid food by themselves, and so much of their diet is in the form of milk, which must supply the newborn with water and nutrients. Since it is the only thing which the offspring can consume, it must deliver everything that is needed in the animal’s diet.

    The milk given to very young baby mammals is called colostrum. It is produced in smaller quantities than later milk, but with a higher concentration of the nutrient. Colostrum provides immune cells, including lymphocytes and multiple forms of immunoglobin, as well as many growth factors. The milk contains high quantities of Vitamin A, salt and proteins. It does not, however, contain much in the way of lipids, potassium and carbohydrate – all of which will appear in later milk.

    Not all milk is the same. The milk given by most mammals is largely made of water, yet seals give more than half its volume to fat. Humans have more sugary milk than that of most other animals, but a much smaller proportion of protein. The composition of the liquid is, in all cases, designed to best suit the nutritional needs of the child in accordance with their native environment.

    Humans and cows produce broadly similar milk, but there are noticeable differences. For example cows’ milk is 4% protein, whereas humans’ is only 1%. This is due to calves needing to grow faster and to a larger size than humans, with which protein assists. Humans, on the other hand, give greater priority to brain and nervous development, where protein is less important. Though both species have similar amounts of fat per given quantity of milk, cows’ is more saturated. This is again due to size versus brain: the human brain triples in size over the first year, requiring a good supply of monounsaturated fatty acids, such as Omega 3 and 6, whereas cows need saturated fat to grow larger bodies.

  • Effects of Industrial Gases

    Air pollution by industrial chimneys

    A review of the environmental problems caused by gases produced by industry.

    Through most of modern history, the subject of a changing environment is usually discussed alongside the issue of man-made pollutants. The most significant part of this is the “greenhouse gases” – substances produced by human industry or agriculture which have been allowed to escape into the air. They are named thus because of the effect they have – trapping heat from the Sun within the Earth’s atmosphere so that the planet stays warm. Increasing the amounts of these gases will therefore increase the temperature.

    Prominent among the greenhouse gases is Carbon dioxide. CO2 is produced whenever hydrocarbons are burned, and therefore large amounts are generated by industries which rely on fossil fuels. It is believed that the concentration of CO2 in the atmosphere has risen by around 30% since the industrial revolution, and it accounts for 75% of global warming by greenhouse gas. Methane (CH4) is another 14% of this, coming mostly from agricultural industries and the rotting of organic materials. A further 8% is caused by Nitrous oxide, which comes from animal waste and nitrogen-based fertiliser.

    There have been many different recorded effects of this, such as the global increase in average temperature. In 1900, the temperature was 3.8 degrees. In 2000 it had risen to 4.4 degrees Celsius – and increase of 0.6. Yet it is predicted that by 2100 the temperature will be 5.8 degrees Celsius, meaning that the rate of temperature rise will have more than doubled.

    This in itself will lead to other damaging effects – such as a dramatic rise in sea levels as ice melts, leading in turn to flooding of coastal settlements and the contamination of drinking water with salt. It would also have a drastic impact on species or communities whose existence is tied to the land – temperature plays a significant role in determining the sustainability of a particular area, and therefore a sudden rise might destroy a habitat, potentially rendering many currently endangered species extinct and bankrupting groups who subsist from agriculture when their land becomes unusable and their crops worthless.

    Another big impact of the temperature rise would be a change in weather – changing water distribution could mean heavier rainfall in some parts of the world and worse droughts in others. This again would force animals to migrate or die. As the creatures move around, so do any pathogens which they carry, which means that diseases are able to spread further than before. It also means more freak weather – such as hurricanes. It is reckoned that, since 1980, the destructive power of the average hurricane has increased by around 50%. thunderstorms, too, have nearly doubled in frequency in some parts of the world and volcanic activity is expected to worsen in the near future.

    Outside of “warming” problems, there is a fear that the constant pouring of exhaust gases into the atmosphere could form a “cloud of smog” over the ground, as has already been observed in some major cities. This could have dire consequences for those living there, as it has been shown to lead to a higher risk of cancer, breathing problems and other maladies.

    Sources: globalwarmingweb.com; wikipedia.org; environmentalleader.com; theguardian.com; environment.about.com; environment.nationalgeographic.co.uk; environmentalgraffiti.com