Expansion on the Recent Discoveries Concerning Nitric Oxide
as presented by Dr. Jack R. Lancaster
Nitric Oxide, or NO, its chemical representation, was until recently not considered to be of any benefit to the life processes of animals, much less human beings. However, studies have proven that this simple compound had an abundance of uses in the body, ranging from the nervous system to the reproductive system. Its many uses are still being explored, and it is hoped that it can play an active role in the cures for certain types of cancers and tumors that form in the brain and other parts of the body.
Nitric Oxide is not to be confused with nitrous oxide, the latter of which is commonly known as laughing gas. Nitric oxide has one more electron than the anesthetic. NO is not soluble in water. It is a clear gas. When NO is exposed to air, it mixes with oxygen, yielding nitrogen IV dioxide, a brown gas which is soluble in water. These are just a few of the chemical properties of nitric oxide.
With the total life expectancy of nitric oxide being from six to ten seconds, it is not surprising that it has not been until recently that it was discovered in the body. The compound is quickly converted into nitrates and nitrites by oxygen and water. Yet even its short-lived life, it has found many functions within the body. Nitric oxide enables white blood cells to kill tumor cells and bacteria, and it allows neurotransmitters to dilate blood vessels. It also serves as a messenger for neurons, like a neurotransmitter. The compound is also accountable for penile erections. Further experiments may lead to its use in memory research and for the treatment of certain neurodegenerative disorders.
One of the most exciting discoveries of nitric oxide involves its function in the brain. It was first discovered that nitric oxide played a role in the nervous system in 1982. Small amounts of it prove useful in the opening of calcium ion channels (with glutamate, an excitatory neurotransmitter) sending a strong excitatory impulse. However, in larger amounts, its effects are quite harmful. The channels are forced to fire more rapidly, which can kill the cells. This is the cause of most strokes.
To find where nitric oxide is found in the brain, scientists used a purification method from a tissue sample of the brain. One scientist discovered that the synthesis of nitric oxide required the presence of calcium, which often acts by binding to a ubiquitous cofactor called calmodulin. A small amount of calmodulin is added to the enzyme preparations, and immediately there is an enhancement in enzyme activity. Recognition of the association between nitric oxide, calcium an calmodulin leads to further purification of the enzyme. When glutamate moves the calcium into cells, the calcium ions bind to calmodulin and activate nitric oxide synthase, all of these activities happening within a few thousandths of a second. After this purification is made, antibodies can be made against it, and nitric oxide can be traced in the rest of the brain and other parts of the body.
The synthase containing nitric oxide can be found only in small populations of neurons, mostly in the hypothalamus part of the brain. The hypothalamus is the controller of enzyme secretion, and controls the release of the hormones vasopressin and oxytocin. In the adrenal gland, the nitric oxide synthase is highly concentrated in a web of neurons that stimulate adrenal cells to release adrenaline. It is also found in the intestine, cerebral cortex, and in the endothelial layer of blood vessels, yet to a smaller degree.
Although the location of nitric oxide was found by this experimentation, it wasn't until later that the function of the nitric oxide was studied. Its tie to other closely related neurons did shed some light on this. In Huntington's disease up to ninety-five percent of neurons in an area called the caudate nucleus degenerate, but no daphorase neurons are lost. In heart strokes and in some brain regions in which there is involvement of Alzheimer's disease, diaphorase neurons are similarly resistant. Neurotoxic destruction of neurons in culture can kill ninety percent of neurons, whereas diaphorase neurons remain completely unharmed.
Scientists studied the perplexity of this issue. Discerning the overlap between diaphorase neurons and cerebral neurons containing nitric oxide synthase was a good start to their goal. First of all, it was clear that there was something about nitric oxide synthesis that makes neurons resist neurotoxec damage. Yet, NO was the result of glutamate activity, which also led to neurotoxicity. The question aroused here is, how could it go both ways?
One supported theory is that in the presence of high levels of glutamate, nitric oxide-producing neurons behave like macrophages, releasing lethal amounts of nitric oxide. It is then assumed that inhibitors of nitric oxide synthase prevent the neurotoxicity. The neurotoxicity of cerebral cortical neurons were studied to test this theory. NMDA is added to the cultures from the brain cells of rats. One day after being exposed to the NMDA for only five minutes, up to ninety percent of the neurons were dead. This reveals the neurotoxicity that occurs in vascular strokes.
It is found through these experiments that nitroarginine, which is a very powerful and selective inhibitor of nitric oxide synthase, completely prevents the neurotoxicity given from the NMDA. Removing the arginine from the mixture protects the cells. Also, homoglobin, which binds with and inactivates nitric oxide, also acts as an inhibitor to the harmful effects of neurotoxicity.
The findings of these experiments led to further tests with a direct exposure of lab rats to the nitric oxide synthase. Because NMDA antoagonists can block the damage caused from the glutamate associated with heart strokes, it is questioned whether nitric oxide has the ability to modulate the destruction caused by the stroke. In an experiment performed by Bernard Scatton in Paris, lab rats were injected with small doses of nitroarginine immediately after initiating a stroke on the rats. The nitroarginine reduced stroke damage by seventy-three percent. This fantastic find proves that there is hope in the evolution and search for cures for vascular strokes.
Nitric oxide may also be involved in memory and learning. Memory involves long-term increases or decreases in transmission across certain synapses after the repetitive stimulation of neurons. They then can detect persistent increases or decreases in synaptic transmission. The role of nitric oxide synthase in these processes. The effects of nitric oxide synthase inhibitors were studied in hippocampus, which is the area of the brain that controls the memory. Due to its many influences, however, further study is needed to determine exactly what role nitric oxide plays in the memory.
Scientists have high hopes for the further investigations of nitric oxide. More experiments lead to greater knowledge, and the effects of this knowledge are receiving a warm reception in this day and age of medicine. The knowledge gained by the study of nitric oxide is hoped to lead to cures and better fighting agents for cancers, tumors, strokes, memory loss, as well as other brain diseases, sensory deprivation, intestinal activity, and various other biological conditions that are affected by neurotransmission. It is amazing already the breakthroughs that have surfaced within the past six years concerning the study of nitric oxide, and its further study is excitedly under way.
Sunday, October 14, 2012
Evolution of Jet Engines
The Evolution of Jet Engines
The jet engine is a complex propulsion device which draws in air by means of an intake,
compresses it, heats it by means of an internal combustion engine, which when expelled it turns a
turbine to produce thrust, resulting in a force sufficient enough to propell the aircraft in
the opposite direction (Morgan 67). When the jet engine was thought of back in the 1920's the
world never thought it would become a reality, but by 1941 the first successful jet flight was
flown in England. Since then the types of engines have changed, but the basic principals have
remained the same.
In 1921 thoughts of a jet engine were based upon adaptations of piston engines and were
usually very heavy and complicated. These thoughts were refined in the 1930's when the turbine
engine design lead to the patent of the turbojet engine by Sir Frank Whittle of Great Britian. It
was Sir Whittle's design that lead Great Britian into the jet age with the first successful flight. At
the same time, the Germans were designing there own jet engine and aircraft which would be one
of the factors that kept Germany alive in World War II. With technological advances by the allies
a prototype turbojet known as the "Heinkel He 178" came into a few operational squadrons in the
German, British, and the American air forces towards the end of World War II. These jets finally
helped the allies to win the war against the axis powers(Smith 23-27).
A later development in the jet industry was the overcoming of the sound barrier and
establishing normal operations up to and beyond twice the speed of sound. Also air force
bombers and transports were able to reach and cruise at supersonic speeds(Silverstein 56-70). In
the late 1950's civil transcontinental jet services started with the Comet 4 and the Boeing 707. In
the mid 1960's all major jet manufacturing companies revised their present engines with new
materials such as aircraft aluminium which made them lighter and turbine changes so they could
compress the air at a much higher pressure so the engine can produce much more thrust.The first
supersonic airliner is the twin turbojet Concorde which flies at over twice the speed of sound
which was brought into regular service in 1976(Smith 27-30). The one company that dominates
the private jet industry is Bombardier which makes the Learjet turbofans, they have an
approximate cruising distance of 1880 nautical miles(Jennings 103).
In the future, turbojet engines will continue to further develop due to the technological
advances made. As in graphite composite wings, thermoplastic chassis, and kevlar skins that have
changed the weight of modern planes and gliders. With these and other developments jet engines
will be honed to produce greater thrust without increases in weight or size. Which will involve
small refinements rather than major changes to the existing engine and engine compartment. In
the near future there will be a substantial reduction of noise emitted from the jet engine, due to a
change in materials and a reduction of vibration in the housing. Right now the jet industry has
over one thousand jets operational at one time, which poses the threat of malfunction and crashes.
With the new computer analysis of problems and the new materials found in the internals of the
engines, there is less of a risk of malfunction than in the past.
Many factors have lead to the popular take over of the jet, replacing the traditional
propeller driven planes. Some of the basic reasons are the speed, fuel economy, and endurance of
the jet engine oveer piston-driven engines. Together with the new refinements and the currently
changing jet industry, future transportation will become faster and safer for the flier.
The jet engine is a complex propulsion device which draws in air by means of an intake,
compresses it, heats it by means of an internal combustion engine, which when expelled it turns a
turbine to produce thrust, resulting in a force sufficient enough to propell the aircraft in
the opposite direction (Morgan 67). When the jet engine was thought of back in the 1920's the
world never thought it would become a reality, but by 1941 the first successful jet flight was
flown in England. Since then the types of engines have changed, but the basic principals have
remained the same.
In 1921 thoughts of a jet engine were based upon adaptations of piston engines and were
usually very heavy and complicated. These thoughts were refined in the 1930's when the turbine
engine design lead to the patent of the turbojet engine by Sir Frank Whittle of Great Britian. It
was Sir Whittle's design that lead Great Britian into the jet age with the first successful flight. At
the same time, the Germans were designing there own jet engine and aircraft which would be one
of the factors that kept Germany alive in World War II. With technological advances by the allies
a prototype turbojet known as the "Heinkel He 178" came into a few operational squadrons in the
German, British, and the American air forces towards the end of World War II. These jets finally
helped the allies to win the war against the axis powers(Smith 23-27).
A later development in the jet industry was the overcoming of the sound barrier and
establishing normal operations up to and beyond twice the speed of sound. Also air force
bombers and transports were able to reach and cruise at supersonic speeds(Silverstein 56-70). In
the late 1950's civil transcontinental jet services started with the Comet 4 and the Boeing 707. In
the mid 1960's all major jet manufacturing companies revised their present engines with new
materials such as aircraft aluminium which made them lighter and turbine changes so they could
compress the air at a much higher pressure so the engine can produce much more thrust.The first
supersonic airliner is the twin turbojet Concorde which flies at over twice the speed of sound
which was brought into regular service in 1976(Smith 27-30). The one company that dominates
the private jet industry is Bombardier which makes the Learjet turbofans, they have an
approximate cruising distance of 1880 nautical miles(Jennings 103).
In the future, turbojet engines will continue to further develop due to the technological
advances made. As in graphite composite wings, thermoplastic chassis, and kevlar skins that have
changed the weight of modern planes and gliders. With these and other developments jet engines
will be honed to produce greater thrust without increases in weight or size. Which will involve
small refinements rather than major changes to the existing engine and engine compartment. In
the near future there will be a substantial reduction of noise emitted from the jet engine, due to a
change in materials and a reduction of vibration in the housing. Right now the jet industry has
over one thousand jets operational at one time, which poses the threat of malfunction and crashes.
With the new computer analysis of problems and the new materials found in the internals of the
engines, there is less of a risk of malfunction than in the past.
Many factors have lead to the popular take over of the jet, replacing the traditional
propeller driven planes. Some of the basic reasons are the speed, fuel economy, and endurance of
the jet engine oveer piston-driven engines. Together with the new refinements and the currently
changing jet industry, future transportation will become faster and safer for the flier.
evaluating an enthalpy change that can not be measured direct
Chemistry Experiment.
Dr. Watson.
Evaluating An Enthalpy Change That Cannot
Be Measured Directly.
Introduction.
We were told that sodium hydrogencarbonate decomposes on heating to give sodium
carbonate, water and carbon dioxide as shown in the equation below:-
2NaHCO3(s)--------> Na2CO3 (s) + H2O (l) + CO2 (g) = DeltaH1
This was given as deltaH1 and we had to calculate as part of the experiment.
This however cannot be measured directly, but can be found using the enthalpy
changes from two other reactions. These being that of sodium hydrogencarbonate and
hydrochloric acid and also sodium carbonate and hydrochloric acid.
We were given a list of instructions in how to carry out the experiment, which are
given later.
List of Apparatus Used.
1 x 500ml Beaker.
1 x Thermometer(-10 to 50oC).
1 x Polystyrene Cup.
1 x Weighing Balance.
1 x Weighing Bottle.
10 grams of Sodium Hydrogencarbonate.
10 grams of Sodium Carbonate.
A bottle of 2 molar HCL.
Diagram.
Method.
Three grams of sodium hydrogen carbonate was weighted out accurately using a
weighting bottle and a balance. Then thirty centimetres cubed of 2 molar HCL was
measured using a measuring cylinder. The acid was then placed into the polystyrene
cup and its temperature was taken and recorded using the thermometer. The pre-
weighted sodium hydrogencarbonate was then added to the solution, and the final
temperature was recorded.
The contents of the cup were then emptied out and the cup was washed out with
water and then thoroughly dried. This was done three times for the sodium hydrogen
carbonate so that I could remove any anomalies that were obtained.
The experiment was then repeated in exactly the same manner except sodium
carbonate was used instead of sodium hydrogen carbonate.
The results were then tabulated, this table is shown below.
Results Table.
Results Table for Sodium Hydrogencarbonate.
Results Table for Sodium Carbonate.
Calculations.
From these results I had to calculate deltaH2 and deltaH3. DeltaH2 refers to the
enthalpy change when sodium hydrogencarbonate reacts with hydrochloric acid, and
deltaH3 is the enthalpy change when the sodium carbonate reacts with the acid.
Firstly however it is necessary to show the equations for the two reactions:-
DeltaH2= 2NaHCO3 (s) + 2HCl (aq)----> 2NaCl (aq) + 2H2O (l) + 2CO2 (g).
DeltaH3= Na2CO3 + 2HCl (aq) ----> 2NaCl (aq) + H2O (l) + CO2 (g)
The enthalpy changes of the two reactions can be worked out using the formula
shown below :-
Energy Exchanged between = Specific Heat Capacity x Mass of the x Temperature
Reactants and Surroundings of the Solution Solution Change.
Therefore the DeltaH2 of the reaction when fitted into the formula is :-
Energy Exchanged between = 4.18 x (84 x 2) x -11.1
Reactants and Surroundings.
This gives the enthalpy change for DeltaH2 to be = -7794.9 Joules per mole.
The same formula is used for DeltaH3:-
Energy Exchanged Between = 4.18 x 106 x 21.8
Reactants and Surroundings.
This gives the Enthalpy change for DeltaH3 to be = 9659.1 Joules per mole.
From these two results we are able to work out what DeltaH1 is likely to be even
though we have not done the experiment. This is done using the formula :-
DeltaH1 = DeltaH3 + DeltaH2 =>
DeltaH1 = 9659.1 + (-7794.9) =>
DeltaH1 = 1864.2 Joules per mole.
Conclusions.
The result obtained will not be a very accurate due to the means by which the
experiment was done. The equipment used was not the most efficient for measuring
enthalpy changes, however it does give a rough estimate to work from. Some errors
of the equipment would have been heat lost through conduction from the reaction
vessel. Also heat may well have been lost through the open top of the container, even
though there was a lid this was not very secure some heat will have escaped through
here.
In summation the experiment was very difficult to undertake as the enthalpy change
for DeltaH1 is hard to determine due to the fact that it thermally decomposes in the
air, causing great problems in calculating its enthalpy change with its surroundings.
Dr. Watson.
Evaluating An Enthalpy Change That Cannot
Be Measured Directly.
Introduction.
We were told that sodium hydrogencarbonate decomposes on heating to give sodium
carbonate, water and carbon dioxide as shown in the equation below:-
2NaHCO3(s)--------> Na2CO3 (s) + H2O (l) + CO2 (g) = DeltaH1
This was given as deltaH1 and we had to calculate as part of the experiment.
This however cannot be measured directly, but can be found using the enthalpy
changes from two other reactions. These being that of sodium hydrogencarbonate and
hydrochloric acid and also sodium carbonate and hydrochloric acid.
We were given a list of instructions in how to carry out the experiment, which are
given later.
List of Apparatus Used.
1 x 500ml Beaker.
1 x Thermometer(-10 to 50oC).
1 x Polystyrene Cup.
1 x Weighing Balance.
1 x Weighing Bottle.
10 grams of Sodium Hydrogencarbonate.
10 grams of Sodium Carbonate.
A bottle of 2 molar HCL.
Diagram.
Method.
Three grams of sodium hydrogen carbonate was weighted out accurately using a
weighting bottle and a balance. Then thirty centimetres cubed of 2 molar HCL was
measured using a measuring cylinder. The acid was then placed into the polystyrene
cup and its temperature was taken and recorded using the thermometer. The pre-
weighted sodium hydrogencarbonate was then added to the solution, and the final
temperature was recorded.
The contents of the cup were then emptied out and the cup was washed out with
water and then thoroughly dried. This was done three times for the sodium hydrogen
carbonate so that I could remove any anomalies that were obtained.
The experiment was then repeated in exactly the same manner except sodium
carbonate was used instead of sodium hydrogen carbonate.
The results were then tabulated, this table is shown below.
Results Table.
Results Table for Sodium Hydrogencarbonate.
Results Table for Sodium Carbonate.
Calculations.
From these results I had to calculate deltaH2 and deltaH3. DeltaH2 refers to the
enthalpy change when sodium hydrogencarbonate reacts with hydrochloric acid, and
deltaH3 is the enthalpy change when the sodium carbonate reacts with the acid.
Firstly however it is necessary to show the equations for the two reactions:-
DeltaH2= 2NaHCO3 (s) + 2HCl (aq)----> 2NaCl (aq) + 2H2O (l) + 2CO2 (g).
DeltaH3= Na2CO3 + 2HCl (aq) ----> 2NaCl (aq) + H2O (l) + CO2 (g)
The enthalpy changes of the two reactions can be worked out using the formula
shown below :-
Energy Exchanged between = Specific Heat Capacity x Mass of the x Temperature
Reactants and Surroundings of the Solution Solution Change.
Therefore the DeltaH2 of the reaction when fitted into the formula is :-
Energy Exchanged between = 4.18 x (84 x 2) x -11.1
Reactants and Surroundings.
This gives the enthalpy change for DeltaH2 to be = -7794.9 Joules per mole.
The same formula is used for DeltaH3:-
Energy Exchanged Between = 4.18 x 106 x 21.8
Reactants and Surroundings.
This gives the Enthalpy change for DeltaH3 to be = 9659.1 Joules per mole.
From these two results we are able to work out what DeltaH1 is likely to be even
though we have not done the experiment. This is done using the formula :-
DeltaH1 = DeltaH3 + DeltaH2 =>
DeltaH1 = 9659.1 + (-7794.9) =>
DeltaH1 = 1864.2 Joules per mole.
Conclusions.
The result obtained will not be a very accurate due to the means by which the
experiment was done. The equipment used was not the most efficient for measuring
enthalpy changes, however it does give a rough estimate to work from. Some errors
of the equipment would have been heat lost through conduction from the reaction
vessel. Also heat may well have been lost through the open top of the container, even
though there was a lid this was not very secure some heat will have escaped through
here.
In summation the experiment was very difficult to undertake as the enthalpy change
for DeltaH1 is hard to determine due to the fact that it thermally decomposes in the
air, causing great problems in calculating its enthalpy change with its surroundings.
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