[IR] Stem Cells

So yeah, that was a short introduction to stem cells.

• These, are probably, the most useful cell in multi-cellular organisms.
• In mammals, there are two main types of stem cells: embryonic stem cells and adult stem cells.

Before we get started, we need to know more about potencies in cells.

1) Totipotency:

• Is the ability of a single cell to divide and produce all the differentiated cells in an organism.
• Totipotent cells include spores and zygotes which are the initial cells formed when two gamete cells are joined by means of sexual reproduction.

2) Pluripotency

• Refers to a stem cell that has the potential to differentiate into any of the three germ layers:
• Endoderm (interior stomach lining, gastrointestinal tract, the lungs)
• Mesoderm (muscle, bone, blood, urogenital)
•Ectoderm (epidermal tissues and nervous system).

3) Multipotency

• Have the potential to give rise to cells from multiple, but a limited number of lineages.
• An example of a multipotent stem cell is a hematopoietic cell — a blood stem cell that can develop into several types of blood cells, but cannot develop into brain cells or other types of cells.

4) Other potencies

• They include ogliopotency and unipotency.
• Ogliopotency refers to the ability of progenitor cells to differentiate into only a few cell types
• Unipotency refers to a cell that has the capacity to develop into only one type of tissue or cell type.

So now, let's get down to business. So, as I was saying, In mammals, there are two main types of stem cells: embryonic stem cells and adult stem cells.

Embryonic Stem Cells

• Embryonic stem cells are pluripotent stem cells
• Derived from the inner cell mass of the blastocyst, an early-stage embryo.

• Embryonic stem cells are distinguished by two distinctive properties: their pluripotency and their ability to replicate indefinitely.
• They are able to differentiate into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm. These include each of the more than 220 cell types in the adult body.

Adult Stem Cells

• Adult stem cells are mutlipotent
• So they have limits to what cells they can develop into unlike the embryonic stem cells.
• However, there are pluripotent adult stem cells but they are rare and generally small in number

• However, there are pluripotent adult stem cells but they are rare and generally small in number
• But can be found in a number of tissues including umbilical cord blood. This is why parents are given the option of storing their babies’ umbilical cord blood, so if the babies develop cancer or other such diseases when they grow up, they can use these stem cells to save their child.

So, how can these stem cells be used for treatment of medical illnesses?

• Medical researchers believe that stem cell therapy has the potential to dramatically change the treatment of human disease.
• A number of adult stem cell therapies already exist, particularly bone marrow transplants that are used to treat leukaemia.

• In the future, medical researchers anticipate being able to use technologies derived from stem cell research to treat a wider variety of diseases including cancer, Parkinson's disease, spinal cord injuries, amongst a number of other impairments and conditions.

So, lets end off with a cartoon.

[IR] Double Rainbow All the Way

Rainbows are a phenomenon that has been widely recognized as a beautiful natural occurrence throughout the stone age and now we understand the physics of the rainbow.
A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicolored arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun.
In a so-called "primary rainbow" (the lowest, and also normally the brightest rainbow) the arc of a rainbow shows red on the outer (or upper) part of the arc, and violet on the inner section. This rainbow is caused by light being refracted then reflected once in droplets of water. 
It is impossible for an observer to maneuver to see any rainbow from water droplets at any angle other than the customary one (which is 42 degrees from the direction opposite the Sun)

The light is first refracted entering the surface of the raindrop, reflected off the back of the drop, and again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of 40–42°. The angle is independent of the size of the drop, but does depend on its refractive index. 

DOUBLE RAINBOW!!!

Although most people will not notice it because they are not actively looking for it, a dim secondary rainbow is often present outside the primary bow. Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear at an angle of 50–53°. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. The secondary rainbow is fainter than the primary because more light escapes from two reflections compared to one and because the rainbow itself is spread over a greater area of the sky. A very dim tertiary rainbow, caused by a triple reflection of sunlight inside the raindrops, has been seen on rare occasions.

Supernumerary rainbow

A supernumerary rainbow—also known as a stacker rainbow—is an infrequent phenomenon, consisting of several faint rainbows on the inner side of the primary rainbow, and very rarely also outside the secondary rainbow. Supernumerary rainbows are slightly detached and have pastel colour bands that do not fit the usual pattern.

Reflected rainbow

When a rainbow appears above a body of water, two complementary mirror bows may be seen below and above the horizon, originating from different light paths. Their names are slightly different. A reflected rainbow will appear as a mirror image in the water surface below the horizon, if the surface is quiet. The sunlight is first deflected by the raindrops, and then reflected off the body of water, before reaching the observer. The reflected rainbow is frequently visible, at least partially, even in small puddles.

[IR] Fireworks - The Science

         Well fireworks to start with are the result of chemical reactions between elements, compounds or mixtures.They are used for mainly aesthetic purposes. The history of fireworks goes back to China but they were not really the fireworks we saw today...
         A long time ago, in a land faraway (actually it is not that far from Singapore...) the villages in China were always terrorized by a big, fat and ugly monster called "Nian". "Nian" always seemed to attack on the first day of the first month of the lunar calendar. One day, an ancient Chinese alchemist found out the magic (as it would seem at that time) of fire and realized its potential to ward off  "Nian". So that nest Lunar New Year, they all waited in their houses with firecrackers put out. And when "Nian" finally came, he was warded off quickly by the noise of the firecrackers and the villagers lived in peace ever since.
        Fireworks are a class of explosive pyrotechnic devices that are designed to burn with coloured flames or sparks. They take many forms to produce four primary effects- sound, light, smoke and floating materials. Fireworks are made out of 5 main components
-Fuel (To allow the firework to burn)
-Oxidizer (To feed oxygen for combustion)
-Mixtures of compounds or elements (For colouration)
-Chlorine (To strengthen the colour of the firework)
-Binder ( To hold the firework together)\



Fireworks come in many different colours based on the mixture and percentage of the compounds and  elements

Red	Strontium (intense red) Lithium (medium red)	SrCO3 (strontium carbonate) Li2CO3 (lithium carbonate) LiCl (lithium chloride)
Orange	Calcium	CaCl2 (calcium chloride)
Yellow	Sodium	NaNO3 (sodium nitrate)
Green	Barium	BaCl2 (barium chloride)
Blue	Copper	CuCl2 (copper chloride), at low temperature
Indigo	Cesium	CsNO3 (cesium nitrate)
Violet	Potassium Rubidium (violet-red)	KNO3 (potassium nitrate) RbNO3 (rubidium nitrate)
Gold	Charcoal, iron, or lampblack
White	Titanium, aluminium, beryllium, or magnesium powders

Here is a stellar fireworks display:

Fireworks at Singapore Flyer Opening

Burj Dubai Opening

May not explain much science, but at least it looks pretty :)

[SR] Forces of Flight

There are four forces of flight -drag, thrust, weight and lift. All four play an important role in how planes fly.

 Drag

As the airplane moves through the air, there is an aerodynamic force present. The air resists the motion of the aircraft and the resistance force is called drag. Drag is directed along and opposed to the flight direction. There are many factors that affect the magnitude of the drag force including the shape of the aircraft, the "stickiness" of the air, and the velocity of the aircraft. We collect all of the individual components' drags and combine them into a single aircraft drag magnitude. Drag acts through the aircraft center of pressure. The drag of the air makes it hard for the plane to move quickly. Another name for drag is air resistance. A streamlined shape slips smoothly through the air. 

Thrust

To overcome drag, airplanes use a propulsion system to generate a force called thrust. The direction of the thrust force depends on how the engines are attached to the aircraft.
On some aircraft, such as the Harrier, the thrust direction can be varied to help the airplane take off in a very short distance. The magnitude of the thrust depends on many factors associated with the propulsion system including the type of engine, the number of engines, and the throttle setting.
For jet engines, it is often confusing to remember that aircraft thrust is a reaction to the hot gas rushing out of the nozzle. The hot gas goes out the back, but the thrust pushes towards the front. Action <--> reaction is explained by Newton's Third Law of Motion.

Lift

As the aircraft moves forward into a stream of air, the wing deflects the air. Some of the air moves to flow above the wing while some of the air moves to flow below the wing.
The wing is curved to help the air that flows above the wing move more quickly than the air that was able to flow below the non-curved bottom of the wing. This curve is called an aero-foil wing.

The air that is moving more quickly above the curved wing starts to put less pressure on the wing while it adjusts to its new stream. Meanwhile, the air that is moving at a consistent speed below the wing maintains its rate of pressure. This quick differential produces lift. The higher air pressure pushes the wing upward into the space where the air pressure is lower.The distribution of lift around the aircraft is important for solving the control problem. Aerodynamic surfaces are used to control the aircraft in roll, pitch, and yaw.

Weight

Weight is a force that is always directed toward the center of the earth. The magnitude of the weight depends on the mass of all the airplane parts, plus the amount of fuel, plus any payload on board (people, baggage, freight, etc.). The weight is distributed throughout the airplane. But we can often think of it as collected and acting through a single point called the center of gravity. In flight, the airplane rotates about the center of gravity.

The motion of the airplane through the air depends on the relative strength and direction of the forces shown above. If the forces are balanced, the aircraft cruises at constant velocity. If the forces are unbalanced, the aircraft accelerates in the direction of the largest force.

[SR] Marvels of Aviation B787

Firstly, welcome to the 3-part mini series Marvels of Aviation, to see the other articles in this series, click the links above.

Aviation. The youngest mode of transportation at just over a 100 years old, but it has since become the premier way to travel long distances. 3 aircraft have changed commercial aviation and have contributed greatly to the advancement of technology for aircraft in the future. This is Marvels of Aviation.

Well, let's get started with a disclaimer. The 3 aircraft that I have chosen are for commercial aviation only, simply because I prefer the look of commercial aircraft to military aircraft.

So, today, let's discuss the Boeing 787. Or what Boeing dubs, the Dreamliner.

It all began in 2001...

The global airline market was upended by the September 11, 2001 attacks and increased petroleum prices, making airlines more interested in efficiency than speed. The airlines in the United States, potential customers of a Sonic Cruiser Boeing was developing, were the worst hit. This caused Boeing to scrap the Sonic Cruiser plan and begin what was known as the 7E7. Boeing wanted to replace its entire airliner product line, in an endeavour known as the Yellowstone Project. The 7E7 was the first stage of that project. It was to replace its existing 767 and 777 product lines. The 7E7 is said to be the most efficient aircraft Boeing has ever created. The "E" was said to stand for various things, such as "efficiency" or "environmentally friendly"; however, in the end, Boeing claimed that it stood merely for "Eight". Boeing later changed its name to 787 in 2005, and it was finally rolled out in 2007, by which time it had reached 677 orders; this is more orders from launch to roll-out than any previous wide-body airliner. On October 26, 2011, the 787 flew its first commercial flight from Tokyo Narita Airport to Hong Kong International Airport on All Nippon Airways. But what made it such a marvel?

Its design. The 787 is primarily made out of composite materials.  Its materials, listed by weight, are 50% composite, 20% aluminium, 15% titanium, 10% steel, and 5% other. So what exactly are these composite materials?

Each 787 contains approximately 32,000 kg of carbon fibre reinforced plastic (CFRP), made with 23 tons of carbon fibre. Carbon fiber composites have a higher strength-to-weight ratio than traditional aircraft materials, and help make the 787 a lighter aircraft. Composites are used on fuselage, wings, tail, doors, and interior. This allows it to become Boeing's most efficient aircraft to date.

Boeing also designed its engines to reduce noise.The engines have have a toothed edge and Boeing calls them chevrons. It allows for a quieter mixing of exhaust and outside air.

Boeing also designed the interior to look and feel better for passengers. They designed the entrance to feel a lot more open so passengers won't feel as cramped. They have also widened the aircraft at eye level so it feels more roomy and spacious for passengers 

They also have cool windows that can tint with a press of a button. Replacing window shades, these cool windows have 5 different shade settings for passengers to personally adjust.

I'm sure that you'll agree with me after reading all these innovations the 787 has pioneered. And it truly is a marvel of aviation.

[SR] Jet Engines

        When humans first observed how birds fly in the sky, they realized that it not only took the birds their light weight, and wings to get them flying, they needed speed. And since the day the Wright brothers built the Wright Plane, the propulsion of aircraft has also evolved, and today, the propeller that had propelled once propelled aircraft into the sky, has been replaced by a bigger, more efficient and faster alternative, the jet engine.

        Aviation is the youngest of all commercial transport and has the fastest growth as well. Many of us has flown on an aircraft before, yet many of us do not understand how the jet engine works. It is a fairly simple concept really, the idea is to suck air in and blast it out at higher speeds, but the technology involved with it is far more complicated.

        To start with, there are 4 types of engines, turbojet, turbofan, propfan, and turboprop.

Propfan

Turbofan

Turbojet

Turboprop

        

       A jet engine works by first sucking in and compressing the surrounding air through the axial compressor. The axial compressor comprises of both moving and stationary blades. The moving blades suck in the air while the stationary ones guide the air and ensures the air enters at the right angle. Then the air flows into the compressor which rotates at very high speed adding energy to the airflow and at the same time squeezing  it into a smaller space. They can compress the air in a 44:1 ratio. The air then moves into a combustion chamber where fuel is mixed in with the air and is ignited and the air would flow at a much faster speed. The temperature of this air would melt the turbine so the compressor directs some air into through a separate channel and this cooler air acts as a coolant for the jet engine. The turbine is another series of blades and it would make the air flow faster. The gas then exits through the nozzle and blasts the aircraft forward.  

Reverse Thrust

As the name implies, it literally sucks air in from the back and blasts it out from the front. Have you ever noticed when landing, a loud roaring of the engine can be heard, that's reverse thrust taking place, it slows down the plane considerably for landing.

Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's exhaust or changing of propeller pitch so that the thrust produced is directed forward, rather than aft. This acts against the forward travel of the aircraft, providing deceleration. Thrust reversers are used by many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. It is also available on many propeller driven aircraft through reversing the controllable pitch propeller to a negative angle.

                                      

[SR] Aviation Month

Its the time of the year again. The June holidays, and you know what that means! A new Feature topic for the month. This June, let's welcome Aviation Month!

Like Animal Adaptations Month last March, I spent lots of effort designing the graphic. No, but seriously, what I wanted to say is that Aviation of Month will also have a tag, and it will be AV.

I have always have had a passion for aviation In fact, the Aerospace industry is where I want my career to be. I hope you will enjoy Aviation Month as much as I'm excited for it.

Just as I had a 4-part mini series titled "Built for..." for my Animal Adaptations Month, there will also be a 3-part mini series this time around titled "Marvels of Aviation", with the tag MA. The series would feature 3 of the biggest breakthroughs in Aviation history. But, because I think commercial aircraft are way cooler than fighter jets that zoom at mach 3, the articles will only feature commercial aircraft.

Starting tomorrow, this is what you can expect for the whole of June:
On 2nd June - Jet Engines.
On 9th June - Forces of Flight.
On 16th June - Marvels of Aviation - Concorde
On 23rd June - Marvels of Aviation - Boeing 787
On 30th June - Marvels of Aviation - A380

[IR] Plate Tectonics

Using modern equipment, scientists known as oceanographers have been able to measure and map out the ocean floor. What these scientists have discovered has helped explain how it is that continents are able to move around on the Earth’s crust.

Deep beneath the waves at the surface of the ocean located almost exactly halfway between the continents are raised areas known as ridges. These ridges are similar to under-water mountain ranges. At other locations we find extremely deep trenches, some reaching many thousands of feet in depth.

Many scientists believe that the ridges represent areas where new crust is being formed as hot magma escapes from the Earth’s core and spreads outward. As the seafloor spreads outward away from the area where magma is being released, the continents are carried across the sea, riding on top of the sima crust.

As new crust is created, older crust submerges back into the mantle, being melted once again. It is believed that the deep ocean trenches are locations where crust is being lowered back into the Earth’s core.

The amount of time that it takes for crust to be created, and later destroyed is approximately 100 million years. Thus, most crust has a lifetime of around 100 million years.

Because continents do not fall back into the Earth’s mantle, they survive much longer. Many parts of the continents we see today are almost as old as the Earth itself.

As new crust is created in a particular location on Earth, it forms what resembles giant plates. One side of the plate is where new crust is being created, while the other side is where older crust is being destroyed.
The plates of the world:

Geologists refer to this process as plate tectonics. As we study plate tectonics, a picture emerges of very old continents riding on top of much younger and ever moving plates. These plates move extremely slowly, at a rate of only about 10 cm per year.

[TR] Term 2 Reflections

Sigh... Well this term was rather sad. My results dropped a lot. :( I got 33/44 for the term test.

Everyone experienced a result drop because the test apparently was really hard. But I think I experienced one of the worse results drop among the whole class. 10 marks!! Thats a lot of marks. In fact almost 20%. How I will get exempted for Science this year. You need to get A1s for all your tests. I got an A2, 73% actually. I just hope I can make it up with Term 3's test. 

I think complacency is really what got me this term. I thought I could still make some magic with what I did with Term 1, as I just studied the night before the test for Term 1 and still got my A1. I saw myself not paying attention during science lessons, sometimes just doodling pictures of test tubes or other random things, I thought I could pull off the same thing for term 2 as I did for term 1. When revising for the Term 2 test. I saw myself having to spot questions and topics because I saw myself not understanding many concepts and topics for chemistry.

I mentioned in term 1, that I saw myself not paying attention during science classes and wanted to change that, turns out i did not. 

I hope that I will learn my lesson in term 3. I will work hard to get back my 42/45.

I guess I have to work really hard for the End of Year Exams since I probably won't be able to get my exemption.

[IR] Formation of Diamonds

Many people think that diamonds look like this:

Well, they are right, but diamonds do not always like this. This is what you get after cuts and many processes. This is what they originally look like:

It looks a lot less pretty right?

Well, this is the post about the formation of diamonds.

Methods of Diamond Formation

Many people believe that diamonds are formed from the metamorphism of coal. That idea continues to be the "how diamonds form" story in many science classrooms.

Coal has rarely played a role in the formation of diamonds. In fact, most diamonds that have been dated are much older than Earth's first land plants - the source material of coal! That alone should be enough evidence to shut down the idea that Earth's diamond deposits were formed from coal.

Another problem with the idea is that coal seams are sedimentary rocks that usually occur as horizontal or nearly horizontal rock units. However, the source rocks of diamonds are vertical pipes filled with igneous rocks.

Four processes are thought to be responsible for virtually all of the natural diamonds that have been found at or near Earth's surface. One of these processes accounts for nearly 100% of all diamonds that have ever been mined. The remaining three are insignificant sources of commercial diamonds.

These processes rarely involve coal.


1) Diamond Formation in Earth's Mantle

Geologists believe that the diamonds in all of Earth's commercial diamond deposits were formed in the mantle and delivered to the surface by deep-source volcanic eruptions. These eruptions produce the kimberlite and lamproite pipes that are sought after by diamond prospectors. Diamonds weathered and eroded from these eruptive deposits are now contained in the sedimentary deposits of streams and coastlines.

The formation of natural diamonds requires very high temperatures and pressures. These conditions occur in limited zones of Earth's mantle about 150 kilometers below the surface where temperatures are at least 1050 degrees Celsius. This critical temperature-pressure environment for diamond formation and stability is not present globally. Instead it is thought to be present primarily in the mantle beneath the stable interiors of continental plates.
Diamonds formed and stored in these "diamond stability zones" are delivered to Earth's surface during deep-source volcanic eruptions. These eruptions tear out pieces of the mantle and carry them rapidly to the surface. This type of volcanic eruption is extremely rare and has not occurred since scientists have been able to recognize them.

Is coal involved? Coal is a sedimentary rock, formed from plant debris deposited at Earth's surface. It is rarely buried to depths greater than 3.2 kilometers. It is very unlikely that coal has been moved from the crust down to a depth well below the base of a continental plate. The carbon source for these mantle diamonds is most likely carbon trapped in Earth's interior at the time of the planet's formation.


2) Diamond Formation in Subduction Zones

Tiny diamonds have been found in rocks that are thought to have been subducted deep into the mantle by plate tectonic processes - then returned to the surface. Diamond formation in a subducting plate might occur as little as 80 kilometers below the surface and at temperatures as low as 200 degrees Celsius.

Is coal involved? Coal is a possible carbon source for this diamond-forming process. However, oceanic plates are more likely candidates for subduction than continental plates because of their higher density. The most likely carbon sources from the subduction of an oceanic plate are carbonate rocks such as limestone, marble and dolomite and possibly particles of plant debris in offshore sediments.


3) Diamond Formation at Impact Sites

Throughout its history, Earth has been repeatedly hit by large asteroids. When these asteroids strike the earth extreme temperatures and pressures are produced. For example: when a 10 kilometer wide asteroid strikes the earth, it can be traveling at up to 15 to 20 kilometers per second. Upon impact this hypervelocity object would produce an energy burst equivalent to millions of nuclear weapons and temperatures hotter than the sun's surface.

The high temperature and pressure conditions of such an impact are more than adequate to form diamonds. This theory of diamond formation has been supported by the discovery of tiny diamonds around several asteroid impact sites.

Is coal involved? Coal could be present in the target area of these impacts and could serve as the carbon source of the diamonds. Limestones, marbles, dolomites and other carbon-bearing rocks are also potential carbon sources.


4) Formation in Space

NASA researchers have detected large numbers of nanodiamonds in some meteorites (nanodiamonds are diamonds that are a few nanometers - billionths of a meter in diameter). About three percent of the carbon in these meteorites is contained in the form of nanodiamonds. These diamonds are too small for use as gems or industrial abrasives, however, they are a source of diamond material.

Smithsonian researchers also found large numbers of tiny diamonds when they were cutting a sample from the Allen Hills meteorite. These diamonds in meteorites are thought to have formed in space through high speed collisions similar to how diamonds form on Earth at impact sites.

Is coal involved? Coal is not involved in the creation of these diamonds. The carbon source is from a body other than Earth.


The Most Convincing Evidence

The most convincing evidence that coal did not play a role in the formation of most diamonds is a comparison between the age of Earth's diamonds and the age of the earliest land plants.

Almost every diamond that has been dated formed during the Precambrian Eon - the span of time between Earth's formation (about 4,600 million years ago) and the start of the Cambrian Period (about 542 million years ago). In contrast, the earliest land plants did not appear on Earth until about 450 million years ago - nearly 100 million years after the formation of virtually all of Earth's natural diamonds.

Since coal is formed from terrestrial plant debris and the oldest land plants are younger than almost every diamond that has ever been dated, it is easy to conclude that coal did not play a significant role in the formation of Earth's diamonds.