Science Makes Sense: Week 48- Chemistry and Social Justice- Where are the Women / People of Color Scientists?

January 30, 2017

I shall never forget my dear friend who obtained her doctorate years before I did in Chemistry  and tried to apply for a job in a different state in India.  Her interviewers were very impressed with her credentials.  Yet, shockingly, they gently dissuaded her from moving away from her husband and children to follow the new job opportunity, even though her spouse was happy to let her persue her career!   She was quite upset by the sexism shown by the men who were interviewing her.

That was in the 70’s and I still see it today.   A few years ago, I was teaching a chemistry class along with a new male teacher to acquaint him with our methodology. He made me demonstrate the laboratory activity and clean up.  Then he proceeded to lecture without even a ‘Thanks ‘ for doing all the grunt work.  I refused to ever work with him after that.

There are numerous examples of talented, intelligent scientists out there who are not white men.  Unfortunately, most students in the field of science and medicine hear about the work of only white men in these fields.  ( As a science student, I heard names like Priestley, Lavoisier, Gauss, Watson, Crick, but never the names of women or non-white chemists, biologists or mathematicians,  for example.  I thought there were none.) There are ample stories of sexism, racism directed at women and non- white scientists and the side- lining of their hard work.  This week and week 52, we shall look at a few of these amazing, pioneering women and people of color scientists from the past to the present.

Mary Putnam Jacobi, an American, was the first woman to be admitted to France’s Ecole deMedicine (Medical School) in 1867. She had already received her MD in the United States.  During this time Edward Clarke, MD at Harvard had written a book called A Fair Chance for Girls claiming that women who spent too many years studying would have under- developed ovaries and would become sterile!   Women menstruated and hence exertions (by studying long hours) during this time would make them sterile. Mary did not believe this and came up with hard facts and numbers using test subjects before, during and after menstruation.  This paper won the Boylston Prize at Harvard and paved the way for women to gain opportunities in higher education, especially the sciences. Mary finished her Medical School in France and continued practicing and lecturing in New York. (Ref.1)

Alice Ball, an African- American, had a Master’s degree in Chemistry from Hawaii in 1915.  She managed to create a less viscous oil that could be injected and absorbed by the body  in the treatment of leprosy.  This was a major breakthrough in the treatment.(Ref.1)

Chien-Shiung Wu was born in Shangai, China, but came to the U. S. to study in Berkeley, California. Her father was an outspoken advocate for women.  She received her doctorate in physics in 1940.  During World War II, she focused her attention on beta decay.  Wu worked on her base material meticulously to prove Fermi’s Theory on beta decay.  She worked on sub-atomic particles relentlessly and isolated the K-meson into an observable state.(Ref.1)

Priyamvada Natarajan is a professor of astronomy and physics at Yale University (featured picture).  She is interested in cosmology,gravitational lensing and black hole physics. Her research involves mapping the detailed distribution of dark matter in the universe using the concept of ‘the bending of light’ coming from distant galaxies! (Ref.2)

Her undergraduate degree was in physics and mathematics, her master’s degree was in Science, Technology and Society from M.I.T., Boston.  Her doctorate work was in theoretical astrophysics.  She was the first woman to be elected fellow of Trinity College, Cambridge.  She has received several awards, including the Sofie and Tycho Brahe professorship in Copenhagen, Denmark.   Priyamvada is deeply interested in institutional change with regards to gender parity in the academic world.  She actively engages in encouraging numerical and scientific  literacy for the public at large. She has been interviewed by NPR and several prestigious newspapers and media outlets.  (Ref.2)

Priyamvada has recently published a book on the history of astronomy called “Mapping the heavens.”(Ref.3)

Ellen Ocho is an astronaut.  She received her master of science and doctorate degrees from Stanford University.  Her doctorate degree was in electrical engineering.  She is a leading research scientist with several patents and is the first Latina to go in space. (She was selected by NASA in 1990.).  She is a veteran of four flights in space.  She has received numerous awards including Outstanding Leadership Medal in 1995.  Besides being an astronaut, engineer and researcher, Ochoa is a classical flutist. ( Ref.4)

I have barely scratched the surface of amazing women scientists, from the past and the present (including names in Nuggets).  Do your own research and marvel at these wonderful women who make us proud!

Nuggets of Information :

According to the U.S. Bureau of Labor Statistics(2015), women make up 47% of the total workforce, and comprise 37% of chemists and material scientists, 28% of environmental and geoscientists and only around 16-12% of engineers.(Ref.5)

Chien-Shiung Wu was called ” The First Lady of Physics”(Ref.6)

British chemist Rosalind Franklin is best known for her pioneering work in crystal diffraction and her role in the discovery of DNA structure.  Though Watson and Crick were awarded the Nobel Prize , very few know about Rosalind’s significant contribution. Unfortunately, she died before the Prize was awarded.  She never complained that Watson and Crick based their article using her research work.(Ref.7)

Vera Rubin who died in December of 2016, had to fight to get access to a telescope.  She was an asro- physicist who worked for decades at the Carnegie Institute of Science in Washington, D.C. She was a pioneer in the discovery of dark matter.  The concept of dark matter had limited evidence in the 70’s as Rubin and her colleagues studied the dim light coming from distant galaxies. (Ref.8).  Thanks to her persistent research we now have evidence not only about dark matter but dark energy and the possibility of ‘multi- verses’.

References:

1.Swaby, Rachel, Headstrong  52 Women who changed Science and the World,  (Broadway Books, New York,2015)

2.astroyale.edu/priya/

3.Natarajan, Priyamvada, Mapping the Heavens,

4.biography.com/people/Ellen-Ochoa-10413023#nasa

5.usnews.com/news/articles/2015/10/21/women-still-underrepresented-in-stem-fields

6.  nwhm.org,go to History Makers and choose’Wu’

7.biography,com/people/rosalind-franklin-9301344#scientific-discoveries-and-credit-controversy

8.latimes.com/local/obituaries/la-me-vera-rubin-20161226-story.html

 

Science Makes Sense: Week47-Organic Chemistry-Terpenes and Terpenoids

December 2, 2016

With the recent election in 2016, several ballot measures were passed that supported medical marijuana as well as recreational marijuana in some states in the U.S.  Terpenes are the main class of aromatic compounds found in cannabis or marijuana as it is popularly called.  Yet, this is only a part of the field of terpenes, terpenoids that are organic hydrocarbons produced by a wide variety of plants.(Ref.1)

The term ‘terpene’ is ascribed to compounds isolated from terpentine, the volatile liquid found in pine trees.   Terpenes were originally used to describe a mixture of isomeric hydrocarbons of the molecular formula C10H16 found in the essential oils obtained from the sap and tissues of plants and trees.  The modern definition is more broad-based:Terpenoids are the hydrocarbons of plant origin of the general formula(C5H8)n, as well as their oxygenated,hydrogenated and de-hydrogenated derivatives. (Ref.2)

Here is a simple table to illustrate the classification of terpenes:

#of carbon atoms      Value of n       Class

10                                   2                     Monoterpenoids(C10H16)

15                                    3                  Sesquiterpenoids(C15H24)

20                                   4.                 Diterpenoids(C20H32)

25                                   5                    Sesterpenoids(C25H40)

30                                   6                   Troterpenoids(C30H48)

40                                   8                   Tetraterpenoids (C40H64)

More than 40     More than 8        Polyterpenoids(C5H8)n

Each class can also be subdivided according to the number of rings present in the structure:

1.Acyclic terpenoids-open structure

2.Monocyclic /bicyclic/ tricyclic terpenoids-containing one/ two/three rings in structure. (Ref.2)

Thermal decomposition of a terpene leads to isoprene as one of the products. (Ref.2). What is an isoprene?  This is the C5H8 building block for a terpene, (where (C5H8)2; i.e., n=2 for the first terpene, as shown in the table above) the structure includes two double bonds: CH2=C(CH3)CH=CH2.

Most terpenoids are colorless fragrant liquids, lighter than water and volatile with steam.  A few are solids like camphor.  All are soluble in organic solvents and mostly insoluble in water, and optically active. Since they can be open-chain or cyclic unsaturated compounds, they can undergo addition reactions with halogens, hydrogen, acids. The addition products have antiseptic properties.  Terpenes also undergo oxidation, polymerization.   On thermal decomposition, most of the terpinoids result in isoprene as one of the products. (Ref.2)

Let us look at some common examples of terpenes:

1.Limonene is comprised of two isoprene units and can be expressed as (C5H8)2 which is then C10H16.  From the above table it is a mono terpene.  Limonene is a mono terpene responsible for the fragrance of citrus fruits.  D- Limonene is widely used as a flavor additive in the food industry as well as an aroma in the perfume industry.  It is also used medicinally to reduce heartburn and gastric reflux.  Sometimes it is used in cleaning solvents and for stripping paint. (Ref.1)  It is a Monocyclic monoterpenoid. (Ref.2)

2. Myrcene is another mono terpene and is the most abundant terpene found in cannabis.  But it is also found in bay leaves, wild thyme, hops, verbena.  It produces analgesic effects in laboratory testing on rats. (Ref.1).  Myrcene is an Acyclic mono terpene. (Ref.2)

3.Pinene: as the name suggests, is found in pines and conifers and it exists as two isomers, alpha and beta pinene, mono terpenes. Turpentine is a large part of pinene.  These pinenes are also present in sage,( both isomers).  Olive, rosemary , sassafras and bergamot contain the alpha isomer while hops and cumin have the beta isomer.  It acts as a natural herbicide and also acts as a bronchodilator in humans. In addition, pinene shows antibacterial, antibiotic properties. (Ref.1)

4. Linalool is a mono terpenoid of the chemical formula C10H18O. It is found in mint,laurel, cinnamon, birch , lavender and some citrus. There are two non- superimposable mirror image isomers for linalool.  Linalool is used as an anxiety inducing drug.  Lavender has been used for thousands of years as a calmative.  Recent tests on rats exhibit its sedative and motor relaxant effects. (Ref.1)( More information about the isomers and examples in Nuggets)

There are several more examples that have not been mentioned here, but suffice to see that terpenes and terpenoids are a wide and extensive resource for us.  Their medicinal uses go back centuries; lavender is just one example. Many herbs and spices like ginger , cloves and cinnamon have been used for centuries in countries like India for home- made health remedies and in the field of Ayurveda medicine.  Today, especially with the possibility of the usage of medical marijuana, the additional terpenes and terpenoids can be combined with cannabis in research and enhancement of therapeutic effects.

Activities for Middle School Teachers:

Students can create the basic isoprene unit and look at common terpene and terpenoid structures.  What limits the structural possibilities? What is the gem dialkyl rule? (Ref.2)

Students  can get a spice or herb used in their foods and find out if it is a terpene or terpenoid.  Let them then build the structure and do a presentation on their terpene/ terpenoid.

Students should have an open discussion about cannabis and talk about the pros and cons of using cannabis.  What kind of societies are created in countries where it is legalized ? Is it better or worse than in the U.S.?  Should there be incarceration for using /possessing small amounts of cannabis? How about focusing on the medicinal uses of cannabis?

Nuggets of information:

Beta- carophyllene, a sesquiterpene is found in cloves, rosemary and hops and exhibits anti- inflammatory effects.  Carophyllene oxide is the substance in cannabis that is identifiable by drug-sniffing dogs. (Ref.1)

Both alpha and beta pinene are present in cannabis; in fact cannabis may contain over 120 terpenes and terpenoids, albeit many of them may be present in trace amounts.  Today the medicinal uses of cannabis, besides the popular assumption that it is mainly used for recreational purposes, is being seriously studied. (Ref.1)

Citral, very similar to Limonene, but has an aldehyde and is an Acyclic mono terpenoid.  It is found in lemon grass oil. (Ref.2)

Other common terpenoids include eugenol (cloves), anethol (fennel, anise), menthol (common cold products),thymol (thyme,oregano), and geraniol (roses).   Camphor is also a terpene. (Ref.3)

Notice that most of the above terpenoids end in ‘ol’ indicating an alcohol or presence of an -OH group.

As terpenoids were found in essential oils, they were used for religious reasons in Ancient Egypt.  Camphor was introduced to Europe from the East by the Arabs in the 11th century.  The process of obtaining  some 60 plant essential oils was described in a book written in 1592. (Ref.3)

 

References:

1.sensiseeds.com/en/blog/medicinal-properties-terpenes-terpenoids/

2.nsdl.niscair.res.in/jspui/bitstream/123456789/700/1/revi

3.food.info.net/uk/qa/qa-fi69.htm

 

 

Science Makes Sense: Week 46:Lanthanides and Actinides

October 31, 2016

I remember seeing the World War II editions of Time magazines among my father’s immense collection of books.  Since they were printed during the war, the sizes were considerably smaller than the regular publication. I think there was an article about plutonium that was used during the war then.

Plutonium is one of the elements found in the Actinide series in the Periodic Table.  Here the 5f orbitals are being filled (from Atomic Number 90-103, i.e.,Thorium, Th to Lawrencium,Lr)  Today we shall also look at the Lanthanide series where the 4f orbitals are being filled from Cerium, Ce (Atomic Number 58) to Lutetium, Lu ( Atomic Number 71) .  The Lanthanide series appear before the transition metal, Hafnium, Hf, in the 6th period, while the Actinide series appear before the transition metal, Rutherfordium, Ru, in the 7th period. These two series are also called the Inner Transition Metals.(Ref.1) In fact the common names are based on the transition metals before these series start: Lanthanum and Actinium respectively.

Lanthanides are formed during the fission of uranium and plutonium.  Lanthanides are like typical metals, silvery -white, they tarnish when exposed to the air, because they form oxides.  They have high melting and boiling points, very reactive and mostly exhibit paramagnetic behavior like oxygen.  Moving from left to right on the Periodic Table, the Lanthanide ions decrease in size, this is called Lanthanide contraction. (Ref.2)

Lanthanides react with water and acids (H+ions) to release hydrogen gas.  They burn easily in air and also react with hydrogen in an exothermic reaction. (Ref.2)

The electro positive nature of the lanthanides and its high reactivity with hydrogen and halides makes it suitable as a catalytic converter in automobiles and in fuel cells.  The ‘f’ orbitals have limited radial extensions; this means that the emission/absorption spectra are sharp, not diffused for the 4f to 4 f levels.  This leads to precise and efficient optical choices of lanthanides in optical instruments ranging from lasers to color television modules. (Ref.3)  Also, lanthanides are used in medicinal applications: as an anti- tumor agent and for kidney dialysis medicine.  Gd, gadalonium, is used in Magnetic Resonance  Imaging  or MRI.  Industrially cerium, Ce,is used in steel manufacturing, since it removes free oxygen and sulfur by forming stable oxysulfides and ties up unwanted antimony and lead. Steel quality is improved when S and O are minimal. (Ref.4)

Actinides are also typical metals, they are soft and silvery- white, have high density and plasticity and can be cut with a knife. Thorium, on the other hand, behaves like soft steel and can be rolled inte sheets or drawn into wires.  Unlike lanthanides, actinides behave like transition metals.  But mostly they are radioactive, paramagnetic and show several crystalline phases.  In fact, actinides have only three naturally occurring elements out of fourteen.  All actinides are radioactive and therefore are toxic and difficult to study (Ref.4).  Just like the lanthanides, actinides react readily with halogens. (Ref.1)  

It is significant to note that the Lanthanides and Actinides are not arranged in columns but rather in two rows.  Much of the chemistry along the row is similar to other members in the row. Elsewhere in the Periodic Table, elements in the same column, not row, have similar properties. (Ref.4)

It is quite amazing that these elements, at the tail end of the Periodic Table, play a controversial as well as a vital role in our lives.

Activities for Middle School Teachers:

Students can practice flash card information on an ‘app’ on smart phones dealing with lanthanides and actinides. (Ref.5)  In addition, students can look at the history of these elements from the time they were discovered and used in constructing bombs for World War II to the use in nuclear reactors and other less controversial applications.

Nuggets of Information:

There are three Lanthanide metals: cerium,Ce,lutetium, Lu and gadolinium, Gd, that have properties similar to the ‘d’ block/ transition metals.  All these three elements contain a ‘d’ electron in their electronic configuration.(Ref.1)

Sometimes these Lanthanide and Actinides are also called rare- earth elements.  However, these elements are not as rare as some of the platinum group noble metals.(Ref.2)

There is an abundance of lanthanides  and the worldwide price is relatively low; substantial ore deposits are found in the U.S.(Ref.3)

Lanthanides exist in the +3 oxidation state since they easily lose two ‘s’ and one  ‘d’ electrons. (Ref.4)

Uranium,U235 is a fissile isotope, which means it can be split through nuclear fission.  Other fissile isotopes are for plutonium Pu, and thorium, Th.  The ability of  an atom to fission depends on the speed of the neutron.  Th requires fast neutrons to fission, while U needs slower neutrons. (Ref.4)

World War II was the first and only time the atomic bomb was used to destroy the enemy.  there were two weapon designs: Assembly” Little Boy” used U 235 and the implosion ” Fat Man” used Pu 239. (Ref.4)

References:

1.boundless.com/chemistry/textbooks/boundless-chemistry

2.chemistry.about.com

3.chemuci.edu/~wevans/lanth.html

4. hope.edu/academic/chemistry/classes/CHM322/Main

5.quizlet.com/116373627/lanthanides-and-actinides-flash

 

Science Makes Sense-Week 45: Oxygen the giver of life

October 17, 2016

When school was over on those hot days in summer, we would all cram into the buses that had limited seats and stand holding on to the metal poles or leather grasps.  Invariably, one of us would sway and faint.  I learned later that it was due to lack of oxygen to the brain and that can occur in a crowded space.

Joseph Priestley discovered this element in 1774 and answered a question that had been vexing scientists and philosophers for a long long time:”How and why do things burn?” Yet, even though he invented many things and was a pioneer in changing the idea of what the composition of air was, he still believed in the phlogiston theory and called oxygen ‘dephlogisticated air’. (Ref.1)

The phlogiston theory is a theory prevalent in 19th century chemistry.  Every combustible substance was supposed to contain phlogiston and this would be removed during combustion.  (Ref.2)   The erroneous idea prevalent because of this theory was that substances lost weight after combustion since usually the ash or residue left behind is lighter than the original substance. But, in reality, there is a net weight gain, because of the formation of oxides, that is not observed since some of the by-products of combustion could be gases that escape.  Hence oxidation was considered to be the removal of phlogiston and reduction was combination with phlogiston! (Ref.2)

Oxygen,O2 ,is a colorless, odorless gas,but the liquid and solid form is pale blue in color. (Ref.3) The electronic structure of oxygen is 1s2 2s2 2p4 which indicates that there is an unpaired electron making oxygen attracted to a magnetic field.  This is explained later.(Ref.4)

All living beings need oxygen to breathe.  Oxygen supports combustion, combines with most elements and is a component of hundreds of thousands of organic compounds.  This gas at room temperature was the atomic weight standard  for all the other elements till 1961.  Then IUPAC (International Union of Pure and Applied Chemistry) adopted carbon 12 as the new standard.(Ref.3)

Oxygen enrichment of steel blast furnaces is a major use of this gas.  Large quantities of  oxygen are needed in the synthesis of ammonia,methanol and ethylene oxide.  It is also used as a bleach, for oxidizing oils, oxy-acetylene welding and determining the carbon content of steel and organic compounds.(Ref.3)

When you look at the electronic configuration of the oxygen molecule, O2, it has two unpaired electrons in the ‘p’ orbital. Meanwhile, for the nitrogen molecule, N2, all the electrons are paired (three unpaired in the atom, that becomes six in the molecule  hence all paired in the ‘p’ level.)  The unpaired electrons in the oxygen molecule move around in their orbitals; this orbital motion generates a loop of current which leads to a magnetic field.   Now the electrons are arranged randomly , causing a cancellation of magnetism.  However, when an external magnetic field is applied, these tiny electrons align themselves in the same direction and the oxygen molecules are attracted to the external magnetic field.  This type of magnetism is called paramagnetism.( Ref.4)

In the case of nitrogen, since all the electrons are paired, half the electronic spin is clockwise and the other half is counter clockwise.   When an external magnetic field is applied, the induced magnetic field is in the opposite direction and repel the applied magnetic field, this is called diamagnetism.(Ref.4)

We already know that oxygen is vital for human respiration. Oxygen therapy is used for people who have trouble breathing due to say, emphysema or pneumonia. Pure oxygen is used also in space suits so the astronauts can breathe. (Ref.5). More uses of oxygen are mentioned in the Nuggets.

While we talk about how this element is used, we must not forget that the everyday action of photosynthesis releases oxygen.   Photosynthesis is the process by which green plants use the energy in sunlight to synthesize material from air and water for growth.   Violet light is absorbed by chlorophyll and the energy obtained is used to split water  when oxygen is given off by the reaction.   Sunlight causes green leaves to produce oxygen.(Ref.6)

We cannot imagine life on earth without this invaluable element.

Activities for Middle School Teachers:

Students need to do Truth Tables to understand math logic  and reasoning.   How would one understand erroneous theories like the phlogiston theory or the geocentric theory using these tables?   What causes certain erroneous theories to survive for a long period?  Is science truly objective sometimes?

Students must be already aware of magnetic substances like iron,nickel and cobalt.  These elements exhibit ferromagnetic behavior. Study the different forms of magnetic behavior.(Ref.7)

Nuggets of Information:

Joseph Priestley,though an Englishman by birth, had to move to America since he gave vocal support to the French and American revolutions. He invented carbonated water and the rubber eraser.(Ref.1)

Lavoisier,the French chemist named the gas oxygen.  He did not believe in the phlogiston theory and burned all books associated with it.(Ref.1)

Regular oxygen is diatomic, i.e., every molecule of oxygen has two atoms in a covalent bond.  Ozone is triatomic,O3,  which is highly reactive, formed by the action of an electric discharge or ultraviolet light on oxygen.  The name is derived from the Greek phrase meaning’I smell’.( Ref.3)

Two-thirds of the human body and nine- tenths of the mass of water is made up of oxygen.(Ref.3)

Oxygen tanks  are present in submarines and airplanes for emergency use.(Ref.5)

Rockets use liquid oxygen to burn fuel and generate lift.(Ref.5)

Scientists use two isotopes of oxygen (16,18) in skeletons to determine the climate thousands of years ago!(Ref.5)

Oxygen gas is poisonous to bacteria that causes gangrene; therefore, it is used to kill gangrene.(Ref.5)

References:

1.acs.org/content/acs/en/education/what is chemistry

2.mirriam-webster.com/dictionary/phlogiston theory

3.chemistry.about.com/od/elementfacts/a/oxygen.htm

4.chemistrynotmystery.blogspot.com(look under”Why is O2 paramagnetic while N2 diamagnetic”)

5.wanttoknowit.com ( type in ‘ uses of oxygen’)

6.jgsee.kmutt.ac.th/excell/JEE613/writeExptExample.html

7.irm.umn.edu/hg2m/hg2m_b/hg2m_bhtml

 

Science Makes Sense-Week 44:Chemistry and Social Justice-The story of Deepwater Horizon and BP:the legacy of oil

September 13, 2016

I look at Hillsborough Bay in Florida to see a placid water body and the seagulls screeching while the brown pelicans sit on the wooden pole perches. And I wonder…… if they could talk to me would they tell me what really happened to their families and the humans around them six years ago during that oil rig explosion?  What really lurks beneath the calm blue waters?

The Gulf of Mexico is known for its rich variety of flora and fauna and also a long coral reef.  Pulley Ridge, 150 miles west of Cape Sable, Florida,has the deepest coral reef in the U.S.  There is another coral reef 110 miles south of the Texas- Loiusiana border.  The whooping crane, the peregrine falcon,piping plover, brown pelican and even the bald eagle make their home here in the gulf.  The shrimp and  fish industry supplies most of our sea food.   There are also a variety of endangered species of whales found in these waters.(Ref.1)  The area is at the same time, also rich in fossil fuel deposits under water.  Off- shore oil rigs have become the way to keep drilling for more oil by those not willing to look for alternative/green sources for our energy needs.

Deepwater Horizon was the name of an ultra-deepwater semi-submersible off-shore oil rig owned by a company called Transocean and leased to BP from 2001.  On 20th April, 2010, while drilling at the Macondo Prospect, an explosion on the rig caused by a blowout killed 11 crew members, ignited a fireball visible from 40 miles away.  The resulting fire could not be extinguished and in the process of doing that, the rig sank, leaving the well gushing and causing the biggest oil spill in U.S. waters.(Ref.2)

Drilling for oil, especially oil that is deep under water, is considered an acrobatic feat.  The crew drills the pipe to hit the oil level and the deeper one goes, the greater is the pressure of oil and mostly methane gas.  The comparison is made with a giant bag of popcorn taken out of the microwave ready to be opened buried under 5,000 feet of ocean and 13,500 feet of earth.  Instead of ripping the bag open, you insert an 18,500- foot straw, actually a pipe and then place a thumb over the straw, so the contents do not explode.  The air in the bag contains methane, the popcorn is the crude oil while the thumb is the cement used to seal the hole. (Ref.3)  Managing the pressure at such depths to bring up the oil and gas mixture in a controlled manner is called well- control. Problems managing the pressures is called a kick , whereas, loss of well- control is called a blowout.(Ref.3)

Why did the blowout occur?  It was later learned that there had been no regular check-ups on backup switches to close the flow of  gas in case of any mal functions.  The oil rig was equipped with visual and auditory alarms to shut off gas which was methane,CH4. Unfortunately, since these alarms make too much noise in the early morning  they were deliberately shut off!(Ref.4)

Following the blowout, the oil kept gushing and BP tried to deal with it by the addition of a dispersant called Corexit so the oil could be dispersed over a larger area.(Ref.5) 

Having somewhat understood the way this disaster occurred and the steps taken by BP, let us look at the chemistry of the chemicals present in the oil rigs during the blowout and later the effects on the species living in and around the gulf area. The burning of the oil rig was due to the methane gas, CH4 that was present which is highly inflammable.  The release of such a large amount of methane gas also leads to the depletion of oxygen in the water and the consequent acidification of the water.   This results in the killing of marine life and all other life dependent on it.  In addition, crude oil contains VOCs which are volatile organic compounds like benzene, toluene and xylene.  Benzene is a known human carcinogen, while toluene and xylene cause nausea, vomiting and fatigue to name a few problems that can ultimately lead to long term health hazards like cancer and birth defects.   Crude oil also contains mercury, lead that are known toxins.  Polycyclic hydrocarbons, also known as PAHs are present in crude oil which contains over a hundred different forms of these hydrocarbons.  Again, they are very toxic and cause cancers in mammals and humans.  When crude oil sits on water or shore, its harmful effects can be carried by the wind and air as a toxic aerosol.  When oil coats the body of the animals in the water, including many birds, it limits its ability to feed, move or even reproduce.  It also harms the external and internal organs of the animals adversely.  In addition, the roots of plants and trees along the marshy grasslands near the gulf shore are killed by the presence of oil.  These plants and trees actually protect those coastal regions to a certain extent from strong hurricanes.  Add to that the immense loss in tourism due to oil washing up on the shores of the sandy beaches dotted all over this area.(Ref.6)

To try to counter the presence of oil, as already noted, BP added the dispersant, Corexit.  This may have hidden the presence of oil to observers, but the dispersing only spread it over a larger area.  The excessive amounts used were unprecedented and its effects are well documented 5 years after the spill in a GAP (Government Accountability Project)report.  More than a dozen whistle blowers were interviewed by GAP.  Here is a summary of the first-hand effect of the devastating impacts of the oil in the water and the subsequent Corexit usage.  The witnesses range from cleanup workers, fishermen, scientists, residents and a physician.

  1. BP syndrome: all GAP witnesses experienced severe health problems, starting with blood in urine, heart palpitations, skin lesions and skin burning leading to kidney and liver damage and respiratory and nervous system damage.
  2. Interviewees were very concerned about long-term results including reproductive damage, endocrine disruption and cancer.
  3. Blood test results revealed high levels of chemical exposure to Corexit and oil; the chemicals here are known to be carcinogens.
  4. Ecological problems: there is evidence of oil and oil debris even after the cleanup was done.  The oil-Corexit mixture has coated the Gulf seafloor and permeated the rich ecological web leading to barren seafloor, widespread damage to the coral reefs.
  5. Majority of fishermen reported that their fish/ sea species had deformities and their catch had decreased substantially after the spill in 2010.(Ref.7)

In conclusion, I have to state that this is a much bigger problem than just BP’s bottom line on profits and gross negligence.  So long as we are dependent on big oil and continue to obtain our energy resources from the fossil fuel industry,we shall go along this slippery slope and destroy our fragile ecosystem and ultimately our lovely planet.

Activities for Middle School Teachers:

VOCs are present in all oil fields.  Students can look at VOCs and its usage in other industries besides oil rigs, e.g., in the paint/ varnish industry.  What safeguards are taken by workers when working with these aromatic compounds?

Students can do simple experiments adding oil to water and seeing how much detergent needs to be added to disperse it. What happens to the oil?  How does a detergent help disperse grease? (Instructor can introduce terms like hydrophilic and hydrophobic here, studying the structures of oil and detergents.) As the ratio of oil to water increases is there a critical point where the detergent is not effective? What other side effects would occur if the detergent is strong like Corexit?

Nuggets of Information:

The Gulf of Mexico has the most methane-rich production area and is also one of the most dangerous places to drill.(Ref.3)

Gas kicks are routine during oil drilling; even blowouts happen a lot of times.  From 1993-1998 there were 11 blowouts, and from 1999-2004 there were 20 blowouts in the Gulf of Mexico!(Ref.3)

Kemp’s Ridley Turtles were ready to be removed from the endangered species list, but thanks to the Deepwater Horizon disaster, they now are facing near extinction.(Ref.8)

Oil kills marshland directly and also poisons the complex mixture of algae, microbes in the soil.(Ref.8)

40% of the Gulf of Mexico’s federal waters were closed to fishing by early June 2010.(Ref.8)

Louisiana is the largest producer of shrimp and oysters in the nation and the second largest producer of crabs.  As a result of this oil rig disaster, the cost to the Louisiana fishing industry could total 2.5 billion dollars.(Ref.9)

A movie about this disaster called “Deepwater Horizon” is set to release soon.(Ref.10)

References:

1.Juhasz,Antonia, Black Tide,p.138 (John Wiley and Sons,2011)

2.deepwaterhorizon.com

3.Juhasz,Antonia, Black Tide,pp.10 ,11(John Wiley and Sons,2011)

4.Juhasz,Antonia, Black Tide,p.24 (John Wiley and Sons,2011)

5.Juhasz,Antonia, Black Tide,p.100 (John Wiley and Sons,2011)

6.Juhasz,Antonia, Black Tide,p.90 (John Wiley and Sons,2011)

7.whistleblower.org/gulftruth

8.Juhasz,Antonia, Black Tide,pp.143-5 (John Wiley and Sons,2011)

9.Juhasz,Antonia, Black Tide,p.163 (John Wiley and Sons,2011)

10.m.imdb.com/title/tt1860357/

Science Makes Sense-Week43:Organic Chemistry-Starches, sugars, cellulose

September 7, 2016

As children, we were fascinated by travel and far-off destinations. We would implore our parents to take a trip around the world and the answer would invariably be:” We cannot afford it, money does not grow on trees!”  If I had studied science then, I could have smartly retorted,” Oh but it does! Money is made from paper and paper comes from trees!”

Starch and cellulose molecules are polysaccharides,which literally means ‘many sugars’. (Ref.1). Cellulose is a long chain of linked sugar molecules that gives wood its strength and is the main component of plant cell walls and the starting point for textiles and paper.(Ref.2)  Cellulose is a poly saccharide polymer with many glucose mono saccharide units (Ref.3) and so is starch.   What is the difference?  Now each glucose unit is joined by acetal linkages.   These acetal linkages are actually an oxygen atom, connecting each glucose unit, left after a reaction between an alcohol group,-OH,with an aldehyde ,CH=O group where the water molecule is removed. (Ref.1)  In cellulose the acetal linkages are beta linkages (acetal group in the upper position) while in starch these are alpha linkages (acetal group in the lower position).  This interesting variation in acetal linkages between starch and cellulose  results in major difference in digestibility in humans.  Humans cannot digest cellulose since they lack the enzymes needed to break the beta linkages, while they can easily  digest starch.  Animals such as cows,sheep, goats and termites  have symbiotic bacteria in their intestinal tract that breakdown cellulose.(Ref.3)

The structure of cellulose and starch vary because of the different acetal linkages as well.  The angles in the beta linkages makes the polysaccharide cellulose a linear chain.  Meanwhile the angles of the alpha acetal linkages in starch form a spiral like a coiled spring.(Ref.3)

These polysaccharides are abundant in nature and their main function is energy storage and are the components of cell walls. They are called mono-polymers because they yield only one type of monosaccharide,namely glucose, after hydrolysis. Hetero-polymers also exist in nature (namely those polysaccharides which yield many kinds of mono-saccharides upon hydrolysis) and include gum, pectin.(Ref.4)  

Polysaccharides are not sweet-tasting like mono or disaccharides. They are non- reducing carbohydrates and do not undergo mutarotation.(Ref.4)  What is mutarotation?  A monosaccharide like D- glucose has two stereo isomers that can co-exist because of change in specific rotation of the chiral compound (a compound that does not superimpose on its mirror image).  The two isomers are called alpha D-glucose and beta D- glucose respectively.  Both are cyclic compounds with one acetal group, 5 carbons, 5 hydroxyl groups (-OH).   In the alpha form, one of the -OH is in the lower position whereas in the beta form it is in the upper position.(Ref.5)

Uses of sugars, cellulose and starch:  these mono/ di and polysaccharides can also be broadly classified as carbohydrates, sources of energy.  Green plants manufacture sugars and most of it is used for plant metabolism and very little accumulates.  However many vegetables and trees are sources of commercial sugar.(SeeNuggets)  Cellulose is a complex carbohydrate and cotton, pure cellulose, is the starting point for artificial fibers.  When wood, also cellulose, is treated with concentrated acids and alkalis, the bond between wood fibers and the lignin ( which holds them together tightly) is broken.  These can be reorganized to form paper.  Treated with more chemicals this can lead to the production of artificial fibers and cellulose plastics.  If you further break it down to the individual elements of carbon, C, hydrogen,H, and oxygen,O, (which is the fundamental elements in cellulose) these elements  can be recombined to form wood sugar, yeast and alcohol.  These are the raw materials for many industrial products.(Ref.6)

From time immemorial, we humans have depended on starch, cellulose and sugar for our energy intake, today we have broadened its usage considerably.

Activities for Middle School Teachers:

Construct molecules with acetal or hydroxyl linkages.  What changes in structures are observed with alpha or beta linkages? Where do you see stereo isomerism? Why or why not? (Remember the lack of rotation in the poly saccharides like cellulose and starch)

Students will look at the timeline for cotton production in the U.S. and other countries.  What was the impact of slavery on cotton productions?  How long did the production of cotton depend on African American labor even after slavery was dismantled?  As students study the structure of cellulose, let them study the history of  cotton production here in the US.

Look at potato, a common starch source for the western world. How were the Irish affected by the potato blight?  How did it change the demographics in the U.S.?

Nuggets of Information:

Cotton is the purest form of cellulose.  In the laboratory, ashless filter paper is, for all practical purposes,a source of pure cellulose.(Ref.2) 

Sucrose or table sugar is the most familiar disaccharide made by linking fructose and glucose.(Ref.2)

The length of the cellulose chain varies greatly: a few 100 sugar units in wood pulp to 6000 units  for cotton! (Ref.3)

Linking just two sugars produces a disaccharide called cellobiose, whereas cellulose is a polysaccharide produced by linking additional sugars in the same way.(Ref.3)

Storage sugars are found in roots of plants like beets, carrots and in stems of plants like sugar cane, sorghum and in flowers such as palm sugar and sugar maple.(Ref.6)

Maize/Indian corn is the source of 80% of the starch made in the U.S., while Europe is the principal producer of potato starch.(Ref.6)

References:

1.education.seattlepi.com/chemical-composition-starch

2.antoine.frostburg.edu/chem/Sienese/101/consumer/far/what-is-cellulose

3. chemistryelmhurst.edu/vchembook/547cellulose.html

4.chemwiki.ucdavis.edu/Textbook_Maps/Organic_Chemistry_Textbook_html

5. ochempal.org/index.php/alphabetical/m-n/mutarotation/

6.faculty.ucr.edu ( look for sugars,starch and cellulose)

 

Science Makes Sense: Week 42-Metalloids and Semi-conductors

August 29, 2016

Even before visiting the west coast of the United States, many of us have heard of Silicon Valley which is a little south of San Francisco.  This is where the electronics/Computer industry boom occurred.  Why is Silicon attached to the name?   This element, besides being famous for creating glass centuries ago is the 20th and 21st century metalloid used in the semi-conductor industry.

Metalloids are considered to be neither metals nor non-metals.  ( As you already know, metals are willing to give up electrons to become cations, while non-metals are eager to take in electrons to become anions.)  Or they could be considered to be both a metal and a non-metal.  The metalloids are on the right side of the Periodic Table, closer to where the non-metals are positioned.  The metalloids  form a stairs-like configuration and include, Boron, B, silcon, Si, germanium,Ge, arsenic,As, antimony, Sb, tellurium,Te, and polonium, Po.(Ref.1)

These metalloids are usually brittle, shiny and behave like electrical insulators at room temperature.  When heated , they behave like conductors.  They also behave like conductors when small quantities of impurities are introduced or ‘doped’ into the crystalline lattice structure of metals.  Metalloids have the electronic structure in between that of the nearly empty outer shell of typical metals and the nearly filled shells of non-metals.  They have enough empty electronic orbitals into which electrons can be moved to conduct an electric current.  Their chemical properties  are also in between electropositive and electronegative atoms.  In physics one would call these elements semi-conductors.(Ref.2)  Semiconductors  have electrical resistance in between that of a conductor and an insulator. (Ref.3)  The electro negativity and ionization energies of metalloids lie between those of metals and non-metals.(Ref.4)

To understand semi-conductors, let us step back a little to look at the history of radios and transistors.  A radio  is a device that needs electricity and needs to be plugged while a transistor runs on batteries and could be carried around, the’boom box’, as it was called.  The latter relies on semi-conductor technology.  The ‘transistor’ is short for ‘transfer resistance’, and is made up of semiconductors and is a part/component used to regulate the amount of current/voltage  used to amplify/modulate/switch on or off an electronic signal.(Ref. 3)  This is the primary building block for an electronic chip, including the CPO ( central processing unit) in every computer we use.

Let us elaborate.  Silicon changes its behavior to a conductor when small amounts of impurities are added to it.

N-type: small quantities of phosphorus, P, or arsenic, As, are added to pure crystals of Si.  P and As have 5 outermost shell electrons, whereas Si has only 4.  The extra electron is free to move around and causes the silicon to turn into a conductor.( Ref.5)

P- type:when boron,B, or gallium, Ga, is added to Si,these atoms have only 3 electrons in their outermost shell. This results in’holes’or positive charges and once again causes a flow of current in the silicon crystal.   A minute amount or P or N- type doping in silicon causes an insulator into a viable conductor; hence the name semi-conductor.(Ref.5)

One can see that the P or N- type doping, evolved to the P-N-P and N-P-N sandwiches leading to transistors and electronic chips through micro-processors.( See Nuggets)  After the invention of transistors in 1954, the field of electronics has evolved dramatically to where we are now, using smart phones and watches like we always had them, handling all our needs from these devices.  Metalloids have been responsible for these amazing changes in our electronic lives.  Yet there are other significant uses for these metalloids that need to be mentioned as well.  Here are some selected few uses that is by no means complete.

Boron has been used to make high resistance glass, especially to thermal shock, control rods in nuclear reactors, also in strong magnets, in CD and DVD players and MRI machines.  Silicon has been used to make high temperature waxes, alloys of Si have been used to make car parts, also in breast implants and contact lenses.  Germanium has a high refractive index and has been used in wide-angle camera lenses and as a catalyst in polymerization reactions, fiber optics as well as in the treatment of AIDS.  Arsenic as an isotope has been used in locating tumors.  It is also used as an insecticide, fungicide and in the treatment of cancer.  Alloys of antimony have been used to make bullets, in acid batteries. In addition Sb has been used as a catalyst in polymer production.  Tellurium has been used to tint glass, cast in alloys to regulate temperature and making solar cell panels as a semiconductor.  Finally polonium has been used in thermoelectric cells because it releases a large amount of energy.

So these elements in a stair-like formation next to the non-metals in the Periodic Table have made quite a splash in our lives!

Activities for Middle School Teachers:

The first computers were automatic arithmetic engines.(Ref.6)  Logic has something to do with it and George Boole started it all.(See Nuggets)  Students can create and study Truth Tables.  The True or False will correspond to 1 or 0 (zero),switch on or off.  This naturally leads students to review/study binary numbers and compare with the decimal system used in arithmetic.  Instructors could help in letting students see the direct connection between binary numbers and computer arithmetic.

Students can look at the history of the digital age from 1947 onwards.  How do the innovations of say, Apple, social media like Twitter,Facebook etc and on-line ordering services affect our daily lives?  How has it affected small stores using traditional/ old modes of business practices?  Let students compare the seismic shifts in our lives today versus the onset of the printing press or the invention of the telephone.

Nuggets of Information:

John Bardeen, Walter Brattain and William Shockley at Bell Labs developed the transistor on December 23, 1947.(Ref.3)

Transistors replaced vacuum tubes in computers in 1954.(Ref.3)

A diode is the simplest possible semi-conductor device, also called a one- way turnstile for electrons.  The transistor is caused by using three layers of N-P-N or P-N-P sandwich; the transistor could be a switch or an amplifier.  A silicon chip is a piece of silicon with thousands of transistors!(Ref.5)

Boolean logic was developed by George Boole in the mid-1800s.  It allows a few unexpected things to be mapped into bits and bytes ( little pathways of logical information).(Ref.7)

References:

1.http://www.chemicalelements.com/groups/metalloids.html

2.https://www.britannica.com/science/metalloid

3.http://www.computerhope.com/jargon/s/semicond.htm

4.schmoop.com/periodic-table/metals-metalloids.htm

5.electronics.howstuffworks.com.diode/.htm

6.i-programmer.info/babbages-bag/235-logic-ev

7.computerhowstuffworks.com/Boolean.htm

Science Makes Sense-Week41:Noble metals

July 11, 2016

In many Indian households, a family’s worth/status is measured by the amount of gold or silver jewelry the women wear.  For many years, actual gold coins were used as monetary currency till other metal coins were produced.  The U.S. Treasury printed the first paper money in 1861.  By the mid 1800’s most of the trading countries wanted to standardize transactions in the booming world market.   They adopted the gold standard.  This meant that governments could redeem paper money for its value in gold.(Ref.1)

Gold,Au, silver,Ag, platinum,Pt, along with other elements  like ruthenium, rhodium,palladium, osmium, iridium, are considered to be the noble metals since they do not oxidize or react easily under normal conditions like most other elements.   These eight elements form a rectangle block in the transition metals group.  The field of physics restricts the definition to include only three elements: gold, silver and copper,Cu, because these three elements have filled electronic ‘d’ bands.  However, in chemistry, copper is known to react quite well and form a series of well-known compounds, hence the former collection of noble metals makes more sense.(Ref.2)

These noble metals make excellent catalysts , especially platinum, since they are not easily oxidized or react with other chemicals that quickly.  Since Noble metals do not react so easily, they are used to clean car exhausts besides being perfect as catalytic  agents.  They are specifically used as catalysts in the manufacture of nitric acid from ammonia. (Ref.3)

Extraction of noble metals: Some of the Noble metals like platinum, iridium and rhodium are found in mines (Check Nuggets) located in some regions all over the world.  The sponge, which is what the raw material from the mines is called, is heated and turned into grains and then big bars or ingots.  After that it is heated again and hammered, it is turned into coils that are further heated to be drawn into very thin wires.  These thin wires are weaved or knitted into fine meshes.  These meshes are used as catalysts in reactions indicated above.(Ref.3)

Other uses of Noble Metals:

Ruthenium,Ru, is used to strengthen alloys with platinum,Pt and palladium, Pd, for electroplating electrical contact materials to be corrosion-resistant, on tips of fountain pen nibs, as a catalyst to split hydrogen sulfide, H2S, and in catalytic converters in automobiles. Rhodium,Rh, is used as a 3-way catlaytic converter in industry and in the production of acetic acid, CH3COOH, from methanol, CH3OH.  It is also used in the electroplating of platinum, Pt and white gold.  Palladium,Pd, is used mainly in jewelry, dentistry, watchmaking, spark plugs for aircraft, surgical instruments.  Iridium,Ir, is a very hard metal and has many applications in industry.  Because of its great resistance to corrosion and a high melting point, it is used in specialized spark plug manufacturing, pen nibs,  as a catalyst and for electrodes.  Machinery parts like spinnerets, balances and high temperature crucibles in the laboratory are also made with iridium, Ir.   The metals, platinum, Pt, gold, Au, and silver,Ag are used as bullion metals, i.e., in making coins as well as jewelry.  Ag is used as an anti- bacterial  medicine, and Pt is used extensively as a catalyst and for electrodes. Meanwhile Au has been used for years  and years to make coins and as a currency.(Ref.4)  Osmium,Os, is used as an alloy ( 90%Pt and 10%Os) for making surgical instruments and the manufacture of pacemakers.  Osmium tetroxide, an oxide of osmium, OsO4, is used in microscopy as a stain for fatty tissue and in fingerprint detection. (Ref.5)

The noble metals group play an important role in our lives, even though they are not as reactive as other metals in the Periodic Table.  Perhaps their low reactivity makes them unique in their applications.

Activities for Middle School Teachers:

What a wealth of fields one can study here: history, geography, economics, science and several cultures!  Let students look at a map and focus on the area once known as Lydia and find out how they fashioned gold.  Where was gold concentrated in the Americas? Study history and geography as the students look at the Aztecs, the Incas and the arrival of Columbus, the conquistadores and the fight for gold.   How did the English colonials in India plunder the gold and wealth there?   Study the wealth in Europe and the Americas especially in some of the old palaces, churches in France, Austria., Germany, Spain, Central America.  Look at the timeline of how gold has been considered such a valuable asset in so many ecomomies.  How do different cultures use gold, silver and the other noble metals today?  Students who come from India can talk about how people wear gold jewelry especially during weddings and special occassions.  Use pictures and take photographs of Indian weddings if possible.

Nuggets of Information:

Sometimes mercury and rhenium are included in the list of noble metals.(Ref.2)

By 560, the Lydians ,in the region between the Mediterranean, Aegean and Black Seas where modern Turkey is situated, succeeded in separating silver from gold and created the first gold coins.(Refs.2,6)

During the days of exploration, the wealthiest country had the most gold.  This explains the reasons why countries like Spain, Portugal and England vied with each other to send explorers like Columbus and others to places like the New World ( the Americas) and the east in search of gold.(Ref.2)

The gold rush of 1948-49 in California initiated the unification of the western part of the United States of America.(Ref.2)

Sometimes the people who work in the manufacture of noble metals from mines use special brushes to recover noble metals from their shoes.  This is called sponge.  One ounce of sponge is obtained from 10-40 tons of rock.(Ref.3)

Noble metals are found in mines that are in South Africa, Canada, Russia  and Zimbabwe. Processing of platinum takes 6 weeks while rhodium takes almost 6 months.(Ref.3)

Palladium is used for blood sugar testing strips and is one of the 4 bullions used by ISO (International Standards Organization) for currency codes.

Rhodium is used as a filter in mammography systems, neutron detectors in combustion systems. Ruthenium is used as a biological stain; staining pectin and nucleic acids.(Ref.4)  A biological stain is used to highlight biological tissue details. (Ref.7)  

When crude platinum was dissolved in aqua regia (a mixture of concentrated nitric and hydrochloric acid: HNO3+HCl) a black metallic powder was formed.  In 1803, the English chemist Tennant recovered  osmium and iridium from this mixture.   The name ‘osmium’ comes from the Greek word ‘osme’ which means unpleasant odor. Os and Ir are very dense; Os is the densest element known.   OsO4, osmium tetroxide is highly toxic and causes lung, skin and eye damage.(Ref.5)

References:

1.http://useconomy.about.com/od/monetarypolicy/p/gold_history.htm

2.http://chemistry.about.com/od/metalsalloys/a/Noble-Metals.htm

3.https://www.bing.com/videos/search?q=where+do+you+find+ruthenium%2c+rhodium%2c+osmium%3f&view=detail&mid=6B2D091A3581A6CE0D986B2D091A3581A6CE0D98&FORM=VIRE

4.http://www.ehow.com/list_6003330_uses-noble-metals.html

5.http://www.chemicool.com/elements/osmium.htm

6.http://www.kidspast.com/world-history/0045-lydians.php

7.http://www.organicdye.com/dyes/biological-stains/

 

 

 

Science Makes Sense-Chemistry and Social Justice-Week40: Fats, salt and sugar: are we eating too much?

June 28, 2016

Two famous Michaels, Michael Pollan and Michael Moss lament the fact that we are cooking less and relying on fast foods.  In their books, ” Omnivore’s Dilemma”,  “Cooked”( Michael Pollan) and “Salt, Sugar, Fat”( Michael Moss), they outline how food is delivered and how home cooking is being sidelined in many houses.(Refs.1,2,3)

I was fortunate to grow up in a home where my parents cooked most of the time.  Even when I started living away in my own home, I did cook almost every day and going out was relegated to once a month or every two months.  These days, I prefer a simple meal at home.  However, most working people eat at odd times and sometimes order in, since they come home tired to plan and prepare a meal.  This has led to more consumption of oily foods, laced with extra salt and desserts/breakfast foods loaded with fat and sugar.  It is also true that the availability of fresh fruits and vegetables at reasonable prices is not as easy in poorer neighborhoods where fast food restaurants are seen more often.  Today we shall look at the prevalence of fast and convenience foods, who tends to buy them and what measures are being taken in certain neighborhoods to encourage healthy eating. We shall look at the additives added in convenience and fast food as well and revisit the saturated, unsaturated as well as trans fats discussion.

First we will look at the term’processed food’.    Processed food is different from home-cooked food in the sense that additives are added to preserve shelf life.  The simplest processed food we see in the supermarket is canned soup.  What does it contain?   A lot of salt is added to preserve it and other additives are also added.  In the inner linings of food cans you find BPA, (Ref.4) which is chemically a bis phenol derivative where two phenol rings are connected via three carbon chains. (Ref.5)  BPA has been known to leach into the soup itself and cause obesity as well as breast and prostate cancers; it has even caused behavioral problems in young girls.  Salt as we know it is sodium chloride, NaCl, and high amounts of sodium ions is known to be responsible for heart attacks and  has lead to strokes (Ref.4)

Besides the additives indicated above let us look at food flavorings and colors, preservatives, chemicals added to change the texture of processed foods.  Among artificial flavoring, butyl alcohol,C4H9OH is one chemical that is added to mimic flavors of naturally occurring foods like butter, fruits.  There are serious health problems caused by too much consumption of this food flavoring.  Artificial sweeteners like aspartame, splenda are used by people with diabetes.  We know that regular sugar causes obesity and heart problems, but the artificial sweeteners consumed continuously causes headaches, seizures and even hallucinations. Benzoic acid(C6H5COOH)  is used  as a preservative in certain pickles, jams and fruit juices and this can cause asthma attacks, hyperactivity in children and neurological disorders.   Artificial colors like Blue 1,2 and some yellows and reds are known to cause certain kinds of cancers.  Vegetable oils that are brominated, ie contain Br, (bromine) a halogen,causes tremors and headaches.  (The Br is added as an emulsifier to prevent the oil from separating out). Carageenan, a  familiar thickener found in ice-creams, jellies has been found to form ulcers and cancers in animal studies.  High fructose corn syrup or HFCS  a fructose polysaccharide from corn, has been known to cause obesity and elevated cholesterol.  We already know the dangers of saturated fats ( less or no double bonds in the fatty acids that produce the oils/fats by esterification) but trans fats are even worse.  This is produced by forcing hydrogen gas over vegetable fats at high pressure and causing -COOH in trans positions hence the name’trans-fats‘.  Many fast food, especially fried foods contain trans-fats and the greater consumption has let to obesity among children and heart diseases.  Nitrates,nitrites of sodium(Na2NO3,Na2NO2) are used extensively in processed meat and is known to be a carcinogen.  And finally, sulfur dioxide, SO2, is added to dried fruits and is responsible for migraine headaches and asthma attacks.(Ref.6)

This list is not exhaustive, there are many more additives, fillers, flavors and colors used in processed foods that are not healthy at all.  But one would imagine that the above chemicals are enough for most of us to start cooking/ eating at home making simple, healthy meals while we know what is going inside our bodies.

But the switch is not easy and between the unhealthy but appetizing messages from the advertising industry, the convenience of ordering take-out and the higher prices of good healthy foods makes it very challenging for consumers to eat a balanced, nutritious meal everyday. (look at Activities and Nuggets)

Activities for Middle School Teachers:

Teachers can encourage students to map out their neighborhoods and actually find out what kind of food stores are available close by.  Then  each student can bring a can of food from home and find out what are the ingredients in them.    What chemicals are there in the additives? Why are they added to the food?  Is it made close by or comes from a far off place?  The teacher can then link geography with that particular can of food and ask students to see why that can of food  had to come from so far away.   The teacher can  introduce words like “locavore”  and”CAFO”and explain the meaning.  What alternatives would make sense? How did their grandparents obtain their daily food?  They could interview each other and find out how often they eat at fast food places, whether their family or friends have a vegetable garden in the summer and where they buy their groceries.  Does culture, where they come from influence what they eat?  Are students willing to try foods from different countries?  What limits them ?  Does having more money make people eat better food?   Does food advertising affect their daily food habits? Why or why not?

Students can also do research on where the food is grown, how it is grown and the difference between organic and regular food, GMO and non-GMO food, and humane or inhumane ways of raising chickens,animals for food consumption and who can afford which kind of food.

Nuggets of Information:

Most artificial flavorings have been banned in the European Union.(Ref.6)

“Food First ” is a book written by Fraces Moore Lappe where she encourages people to understand the politics of food and why growing your own food is the best way to control what one can eat.(Ref.7)  It is also necessary not to be a passive consumer but understand that supermarkets encourage us to consume high fat, high sugar products by simple things like arrangement of cereals / cans/ processed foods in an aisle.(Ref.8)

Morgan Spurlock in the movie”Supersize Me” makes us think twice about eating at fast food places too often.  He actually did an experiment on himself by eating fast food day and night for a month at McDonald’s and noticed how adversely it affected his own health!(Ref.9)

CAFO, or concentrated animal feeding operations or factory farms, keep animals in small confined spaces to feed and take care of them before butchering them for meat.  There have been enough studies done to show that the process is inhumane and unhealthy.(Ref.10)

References:

1. Pollan, Michael, Omnivore’s Dilemma (Penguin Press,2006)

2.Pollan, Michael, Cooked (Penguin Press,2013)

3.Moss, Michael, Salt, Sugar, Fat (Random House,2013)

4.http://www.rodalewellness.com/health/canned-soup

5.http://www.chemspider.com/Chemical-Structure.6371.html

6.http://peopleforethicalliving.com/health-and-fitness/food-choices-nutrition/dangerous-food-additives/

7.Lappe, Frances Moore,Food First (Souvenir Press Ltd.,1980)

8.http://www.regainedwellness.com/supermarket-psychology/

9. Supersize Me! the movie with Morgan Spurlock

10.Foer,Jonathan Safran ,Eating Animals (Little Brown and Co.,2009)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Science Makes Sense- Week 39:Organic Chemistry,Lipids, oils and fats

June 21, 2016

Almost every child in America gets its first taste of fast food with a packet of fries: Mmmm…so good! As children we grew up with occasional treats of fried potatoes that were irresistible. When I first landed in the U.S.,I always bought a bag of potato chips to remind me of fried food in India.
Oil has a unique way of adding flavor to any food. Today let us look at the chemistry of oils. Lipids are biological chemicals that do not dissolve in water.(Ref.1) These are a group of fat soluble compounds found in the tissues of plants and animals. Fats and oils are a sub-set or subgroup of lipids and are basically storehouses of energy. But lipids play an important role in the formation of cellular membranes,cellular signaling, nutrient functions with relationships to vitamins A,D,E,and K as well as being storehouses of energy. Furthermore, lipids are complex molecules with carbon, hydrogen and oxygen as well as nitrogen and sulfur and other small constituents.(Ref.2)
Fats and oils share a common molecular structure; fats are solids at room temperature, oils are liquids. What is the molecular structure?
They are esters of tri-alcohols, i.e., three -OH groups,also called glycerols,hence fats and oils are also commonly known as glycerides.  An ester has the H in the -OH group replaced by  a carbon chain and since there are 3 -OH groups there could be three different carbon chains called R1, R2 and R3 respectively.(Ref.1)  Remember that an ester in organic chemistry is like a salt in inorganic chemistry .  A salt is the neutralization reaction between a base/alkali and an inorganic acid, whereas an ester is a similar kind of neutralization reaction between an alcohol and an organic acid.   The more accurate name would be Triacylglycerols.   Hydrolysis (or reaction with water) of fats leads to glycerols and fatty acids.(Ref.1)

Triglyceride molecules contain carbon and hydrogen molecules and usually six oxygen atoms in every molecule.  This makes them highly reduced or unoxidized.  They resemble the hydrocarbons in petroleum and are good sources of fuel.  In fact the normal human body stores fats as fuel/ energy for several weeks’ survival.  Plants too do the same thing and this allows them to deal with unpredictable sources of food supply.(Ref.1)

A triglyceride is called a fat if it is a solid at 25°C, if it remains a liquid at this temperature, it is termed an oil.  The difference in melting point reflects the difference in the degree of unsaturation and number of carbon atoms in the original fatty acids that resulted in the triglyceride. (Ref.3)

Pure fats and oils are colorless,odorless and tasteless.  They are lighter than water, their densities are usually around 0.8gm/cc. They are poor conductors of heat and electricity and hence are excellent insulators for the body, slowing the loss of heat through the skin.(Ref.3)

The double bonds in fats and oils can undergo hydrogenation as well as oxidation.  The hydrogenation of oils is used commercially to produce margarine.  Most fats are obtained from animal sources whereas most plant sources produce oils.  Saturated fats/oils are derived from saturated fatty acids ( less or no double bonds) while unsaturated fats/oils are derived from unsaturated fatty acids ( more double bonds).  The high consumption of saturated fats, along with high cholesterol leads to increased risks of heart disease..(Ref.3)

The study of lipids, fats and oils indicates how necessary they are in the function and maintenance of our body’s functions.  However, too much of saturated fats and oils consumption today, especially because of the  fast food industry and in the changes in our lives has led to all kinds of medical problems.  We shall look closer at this topic next week.

Here is a small table to illustrate the predominance of saturated fatty acids in fats and more of the unsaturated fatty acids in oils:.(Ref.4)

Animal fats   Saturated acid(%)             Unsaturated Acids(%)

C10 &less     C12     C14     C16    C18        C18(a)C18(b) C18(c)

Butter     15         2          11        13        9            27      4         1

Lard             –        –             1         27     15          48    6          2

Plant oils               Saturated acid(%)           Unsaturated acids(%)

Coconut     –       50           18        8     2             6      1           –

Corn           –        –             1        10      3            50     34        –

Olive           –         –           –          7        2             85       5       –

Safflower   –         –            –         3        3             19     76       7

Activities for Middle School Teachers:

Let students make models of different fatty acids and triglycerides. Students need to research the reasons why unsaturated fats are not solids even though there are more double bonds here and the molecule ( fatty acid or corresponding triglyceride) may be dense and therefore could become a solid.  The Van der Waals weak intermolecular forces are stronger when you have long chain straight molecules; this happens with saturated fat molecules.  On the other hand, the presence of double bonds causes kinks in the structures making them non-planar.  Students will find a relationship between melting points and straight-chain versus non-planar structures. Students can plot a graph and present results.(Ref.5)

Nuggets of Information:

When all three hydroxyl groups (-OH) groups in the glycerol molecule are esterified with the same fatty acid, the resulting glyceride is called a simple glyceride.  In nature, you never see a simple glyceride, since the esterification in nature involves several different fatty acids.  That is because naturally occurring acids are a mixture of several fatty acids.(Ref.3)  No single formula can be written to represent naturally occurring fats and oils.  They may be derived from several different fatty acids.  Palmitic acid is the most abundant saturated fatty acid and oleic acid is the most abundant unsaturated fatty acid.(Ref.3)

Even though most fats are derived from animals, the exception is fish oil; triglycerides from fish are found as oils..(Ref.4)

Seeds contain a lot of oil/fats; the stored energy helps seedlings during germination.  later, they have solar energy available for photosynthesis.(Ref.3)

Hydrolysis of fats and oils in the presence of a base produces soap and the process is called saponification.(Ref.3)

Lipids can be  further classified as fats, oils, phospholipids, waxes, sterols .(Ref.4) Phospholipids  are a class of lipids similar to triglycerlides , where the fatty acid from which it is derived contains a phosphorus atom; they are present in cell membranes. Sterols are a class of lipids with structure similar to cholesterol.(Ref.6)  Cholesterol comes under the umbrella of steroids which have a carbon backbone with four fused ring-like strucures and a hydoxyl group (-OH).  Waxes are esters of a long-chain fatty alcohol and a fatty acid.  Many plants and fruits have a waxy coating to prevent water loss.(Ref.7)

Ear wax is composed of phospholipids and esters of cholesterol!(Ref.7)

References:

1.http://scifun.chem.wisc.edu/chemweek/pdf/Fats&Oils.pdf

2.http://www.differencebetween.info/difference-between-lipids-and-fats

3.http://chemwiki.ucdavis.edu/Textbook_Maps/General_Chemistry_Textbook_Maps/Map%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/17%3A_Lipids/17.2_Fats_and_Oils

4.http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/lipids.htm

5.http://chemistry.stackexchange.com/questions/4058/saturated-vs-unsaturated-fats-structure-in-relation-to-room-temperature-state

6.https://quizlet.com/94654736/chapter-5-lipids-fats-phospholipids-and-sterols-flash-cards/

7.http://biology.about.com/od/molecularbiology/ss/lipids.htm