Another month starts in the SCIence Garden with no visitors to appreciate the burgeoning growth of fresh new leaves and spring flowers, but that doesn’t mean we should forget about it!
Hopefully in our absence the Laburnum tree in the garden, Laburnum x watereri ‘Vossii’ will be flowering beautifully, its long racemes of golden yellow flowers looking stunning in the spring sunshine!
Laburnum x watereri ‘Vossii’ in the SCIence Garden
This particular cultivar originated in the late 19th century in the Netherlands, selected from the hybrid species which itself is a cross between Laburnum alpinum and L. anagyroides. This hybrid species was named for the Waterers nursery in Knaphill, Surrey and was formally named in a German publication of 1893 (Handbuch der Laubholzkunde, Berlin 3:673 (1893)
The laburnum tree is found very commonly in gardens in the UK, and is noticeable at this time of year for its long chains of golden yellow flowers. However, the beautiful flowers hide a dark side to this plant. The seeds (and indeed all parts) of the tree are poisonous to humans and many animals. They are poisonous due to the presence of a very toxic alkaloid called cytisine (not to be confused with cytosine, a component of DNA). Cytisine has a similar structure to nicotine (another plant natural product), and has similar pharmacological effects. It has been used as a smoking cessation therapy, as has varenicline, which has a structure based on that of cytisine. These molecules are partial agonists at the nicotinic receptor (compared to nicotine which is a full agonist) and reduce the cravings and “pleasurable” effects associated with nicotine.
Cytisine is found in several other plants in the legume family, including Thermopsis lanceolata, which also looks stunning in early summer and Baptisia species, also growing in the SCIence Garden and flowering later in the year.
In 2018 there were 9.6 million deaths from cancer and 33% of these were linked to exposure to tobacco smoke.* Since the link between smoking and lung cancer was established in 1950, the market for smoking cessation therapies has increased enormously. In 2018 it was worth over 18 billion dollars annually worldwide and is projected to increase to 64 billion dollars by 2026.** Staggering! Varenicline, sold under the brand names Champix and Chantix, is one of the most significant smoking cessation therapies apart from nicotine replacement products.
If you see a laburnum tree whilst out on your daily allowed exercise this month, have a thought for its use as a smoking cessation therapy!
* Data from the Cancer Research UK website https://www.cancerresearchuk.org/health-professional/cancer-statistics/worldwide-cancer#heading-Zero accessed May 2020.
Who is Dmitri Mendeleev?
Russian chemist, Dmitri Mendeleev was born in 1834 in a Siberian village. His early life has been described as tumultuous; his father lost his sight and died when Dmitri was thirteen, leaving his family in financial difficulties.
His mother prioritised Dmitiri’s academic potential, taking him and his sister to St Petersburg, where he studied at the Main Pedagogical Institute. When his mother died, he carried out his doctoral research in St Petersburg where he explored the interactions of alcohols with water.
Between 1859 and 1861 he went to Paris to study the densities of gases, and he travelled to Germany where he studied capillarity and surface tension that subsequently led to his theory of ‘absolute boiling point.’ In 1861 he returned to Russia to publish everything he knew on organic chemistry in a 500-page textbook, and by 1864 he became a professor at the Saint Petersburg Technological Institute and Saint Petersburg State University.
As he continued his research, he tried to classify the elements according to the chemical properties. He became aware of a repeating pattern – elements with similar properties appeared at regular intervals. He arranged the elements in order of increasing relative atomic mass and noticed the chemical properties of these elements revealed a trend, which led to the formation of the periodic table.
Beyond his work in chemistry, during the 1870s, he devoted time to help the Russian industry, particularly in strengthening the productivity in agriculture. He became very active in exploring the Russian petroleum industry and developed projects in the coal industry in the Donets Basin. Additionally, he was responsible for creating and introducing the metric system to Russia.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about the first element in the periodic table, hydrogen!
Hydrogen isn’t just for keeping balloons afloat. Image: Pixabay
Hydrogen (H2) gas has many uses in modern engineering. Scientists are always searching for cheaper, more renewable fuel sources that have a lower negative impact on the environment. Hydrogen was frequently used to generate energy in the past, and this drive for more renewable energy has given hydrogen-derived fuel a new lease of life.
Hydrogen can be used in fuel cells. These act like batteries, generating their energy from a reaction between hydrogen and oxygen (O2). Hydrogen fuel cells have been incorporated into many modern technologies, including automotive. As the reaction occurring only generates heat, electricity and water, fuel cells are significantly better for the environment than many alternatives. Hydrogen is also much cheaper as a commodity that typical fuels.
Hydrogen fuel cells can now be used to power automotive vehicles, including cars!
Engineering cooling systems can use hydrogen. The gases physical properties make it 7-10 times better at cooling than air. It can also be easily detected by sensors. Because of this, hydrogen is used in cooling systems, which are generally smaller and less expensive than other available options.
Hydrogen gas can be used in reactions. The most famous reaction using hydrogen is the production of ammonia (NH3), also known as the Haber process. The Haber process was developed by Fritz Haber and Car Bosch in the early 20th century to fill the need to produce nitrogen-based fertilisers. In the Haber process, atmospheric nitrogen (N2) is reacted with H2 and a metal catalyst to produce NH3.
Nitrogen-based fertilisers are still used today, but ammonia was one of the first to be commercially produced.
Ammonia is a valuable fertilised, providing much needed nitrogen to plants. It was used on a variety of agricultural plants, including food crops wheat and maize, in the 19th and early 20th century.
Chemists undertake other chemical reactions, such as hydrogenation and reduction, that utilise hydrogen, to make commercially valuable products. Some physical properties of hydrogen make it tricky, and often dangerous, to use in industry. However, careful control of conditions allow for its safe use on larger scales.
Hydrogen gas can be explosive, making it often dangerous to use.
Producing hydrogen gas
There are many ways to produce gaseous hydrogen. The four main sources of commercially produced hydrogen are natural gas, oil, coal and electrolysis. To obtain gaseous hydrogen, the fossil fuels are ‘steam reformed’, a process which involves a reaction with steam at high pressure and temperature.
Electrolysis of water is another method that is used in hydrogen production. This method is 70-80% efficient. However, it often requires large amounts of energy, specifically in the form of heat. This heat can be sourced from waste heat produced by industrial plants.
So, whats all this hot air about hydrogen? Source: Tedx Talks
An alternative method for producing hydrogen is via biohydrogen. Hydrogen gas can be produced by certain types of algae. This process involves fermentation of glucose. Some hydrogen is also produced in a form of photosynthesis by cyanobacteria. This process can be used on an industrial scale.
Overall, hydrogen technology, whether it be new developments, such as hydrogen fueled cars, or old, like the Haber process, remains critical to the chemical industry.