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Gary Ray R
Worked at Mechanical Engineer
Attended U of Hawaii '83, Cal Poly '96
Lives in Central Coast California
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Gary Ray R

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Now this is SCIENCE-fiction.  And I really like it.  Always leave them wanting more +SciFi Author: Lacerant Plainer, and I want more. 
Marge was quite amazed at the way things had gone. She was taken aback at the speed at which she was whisked away .... things were explained to the relevant people... and before anyone knew what was what, she was on her way t...
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+Gary Ray R glad you liked it :) I am humbled by the compliment! +Alicia Patrick thanks so much!
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Gary Ray R
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• Astronomy/Astrophysics ☄  - 
 
☾Lunar Eclipse Visible Tonight in North America☽
April 14,  2014
Don't forget tonight is a total lunar eclipse visible from most all of North America.  Our favorite Astrophysicist +Brian Koberlein explains it well in this post.

For times it will be visible in your area check out the Sky and Telescope article. 

http://www.skyandtelescope.com/astronomy-news/observing-news/aprils-total-eclipse-of-the-moon/
 
Blood Moon

This week those of us in the western hemisphere will have the chance to observe a lunar eclipse.  It will happen in the evening/morning of April 14/15, reaching peak darkness at about 3 a.m. EDT (0600 GMT).  Depending on the darkness of your sky, the Moon may be invisible to the naked eye, or it may appear as a dark, blood moon.

A lunar eclipse occurs when the Moon passes through the shadow of the Earth.  For this reason, lunar eclipses occur when the Moon is in its full phase.  Given that the Moon orbits the Earth, you might wonder why there isn’t a lunar eclipse every month.  If the orbit of the Moon were exactly in line with the orbit of the Sun, then that is exactly what would happen. But the Moon’s orbit is tilted about five degrees relative to the orbit of Earth, and this means that the Moon is often slightly above or below the Earth’s shadow when it passes through its full phase. So most months there is no lunar eclipse.

For the Moon to be lined up in the right way, it has to be located near the plane of the Earth’s orbit when it passes behind the Earth, and this only happens twice a year, about 6 months apart. This is why there are “eclipse seasons” in Spring and Fall. There are at least two lunar eclipses each year, but there can be as many as 5.

Not all lunar eclipses are alike. As seen in the image below, since the Sun is larger than the Earth, there are regions where only part of the Sun is blocked by the Earth, and the resulting shadow is called the penumbra. For a much smaller region where the Sun is completely blocked by the Earth, the shadow is called the umbra. The type of eclipse that occurs depends on whether the Moon passes through umbra or penumbra.

If the Moon just passes through penumbra, then what occurs is a partial lunar eclipse.  In this case only part of the moon will appear dimmed.  If the Moon passes through the umbra, then you get a total lunar eclipse.  It is while passing through the umbra that you can observe a blood Moon.  The reason the Moon can appear red rather than completely dark is that some sunlight is refracted by the Earth’s atmosphere.  If you were standing on the Moon during a lunar eclipse you would see the Earth surrounded by a ring of sunset.

This particular lunar eclipse is a total one, and it marks the first of four consecutive total lunar eclipses.  One for each eclipse season every six months.  So if you miss this one, you’ll have another three chances over the next year and a half.  After that, total lunar eclipses will be less common for a while.

So brace yourselves, the eclipses are coming. 

Image: Schematic of a lunar eclipse. Credit: Wikipedia
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We had a stunning full moon last night in the UK. Hope our cousins in US enjoyed the eclipse. 
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• Chemistry  - 
 
SF₆ You Have Seen The GIF, What is it Used For?

Sulfur Hexafluoride, is used for a lot more than cool demonstrations.  Learn more about this fascinating industrial gas in this post from Materials Science on G+.
 
Sulfur Hexafluoride, The Rest of The Story

We have all seen the GIF made from a video taken at the Physikshow (2007) of the University of Bonn of Sulfur Hexafluoride (SF₆). The original YouTube is below.  It is a demonstration of the density of SF₆ as compared to regular air.  
Density of SF₆  6.17 g/L,  Density of air at sea level is (1.225 g/L)  

That is what makes the demonstration below possible. The SF₆ is so much denser than air, that it acts like an invisible liquid filling the small glass tank.  As shown on MythBusters, it will also make your voice sound much lower in pitch after you breath it in.  It is safe to do this, but I would not recommend it. 

Sulfur Hexafluoride  was discovered by Henri Moissan and Paul Lebeau in 1901 and is a very non-reactive dense gas. It is non reactive because of Steric hindrance, which occurs when the large size of groups within a molecule prevents chemical reactions that are observed in related molecules with smaller groups.  Wiki

As stated in Wiki, it has almost no reaction chemistry, with the exception of a very exothermic reaction with the metal lithium. 

While it makes for a cool physics or chemistry demonstration, what is it used for?

One of its major uses is as a very good insulating gas or dielectric gas.
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges.    
That is where I first learned about this unique gas, when I was working for GE in the Power Delivery branch.   
SF₆  is used in the electrical industry as a gaseous dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment, often replacing oil filled circuit breakers (OCBs) that can contain harmful PCBs. SF₆  gas under pressure is used as an insulator in gas insulated switchgear (GIS) because it has a much higher dielectric strength than air or dry nitrogen. This property makes it possible to significantly reduce the size of electrical gear.  Wiki

Wiki states:
More than 10,000 tons of SF₆  produced per year, most of which (over 8,000 tons) is used as a gaseous dielectric medium in the electrical industry.

 What are those other uses?

Medical use.
SF₆  is used to provide a tamponade or plug of a retinal hole in retinal detachment repair operations in the form of a gas bubble.  and SF₆  is used as a contrast agent for ultrasound imaging

Tracer compound
Sulfur hexafluoride was the tracer gas used in the first roadway air dispersion model calibration; this research program was sponsored by the U.S. Environmental Protection Agency and conducted in Sunnyvale, California on U.S. Highway 101.
Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St John's Wood tube station in London, United Kingdom on 25 March 2007
Sulfur hexafluoride is also routinely used as a tracer gas in laboratory fume hood containment testing.

Military use
The United States Navy's Mark 50 torpedo closed Rankine-cycle propulsion system is powered by sulfur hexafluoride in an exothermic reaction with solid lithium
The torpedo's Stored Chemical Energy Propulsion System uses a small tank of sulfur hexafluoride gas which is sprayed over a block of solid lithium, which generates enormous quantities of heat, in turn used to generate steam. The steam propels the torpedo in a closed Rankine cycle, supplying power to a pump-jet. This propulsion system offers the very important deep water performance advantage in that the combustion products, sulfur and lithium fluoride occupy less volume than the reactants, which means the torpedo does not have to force these out against increasing water pressure as it approaches a deep-diving submarine.  Wiki

Semiconductor Industry uses
SF₆   plasma is also used in the semiconductor industry as an etchant.

Metallurgical uses
Component of inert atmosphere during the primary casting of Aluminum and Magnesium. Refining agent for Aluminum foundry applications. N2 / SF₆  gas mixtures (5 - 10 % by volume of SF₆ ) are employed to refine pure Aluminum or its alloys at melt temperatures in the range 650 - 750 °C. SF6 is a source of fluorine atoms reacting in the melt and removing inclusions of H2, oxides, particles and other casting impurity.  www.Fluorocarbons.org

And finally SF₆ is a very strong greenhouse gas. 
According to the Intergovernmental Panel on Climate Change, SF₆ is the most potent greenhouse gas that it has evaluated, with a global warming potential of 23,900 times that of CO2 when compared over a 100-year period.
Sulfur hexafluoride is also extremely long-lived, is inert in the troposphere and stratosphere and has an estimated atmospheric lifetime of 800–3200 years Wiki

So the next time you see the GIF or the YouTube of SF₆ you will know the rest of the story. 

Sources.
http://www.fluorocarbons.org/chemical-families/sf6/sf6-products-applications  
http://en.wikipedia.org/wiki/Sulfur_hexafluoride
http://en.wikipedia.org/wiki/Dielectric_gas
http://en.wikipedia.org/wiki/Mark_50_torpedo

http://www.physikshow.uni-bonn.de/

Schneider Electric has an excellent paper that discusses how the gas is made and used in industry. 
http://www2.schneider-electric.com/documents/technical-publications/en/shared/electrical-engineering/breaking-techniques-switchgear/general-knowledge/ect188.pdf

A hat tip to +Shamail Ahmad who got me started on this.

The short video below is:
Ship floating on nothing! :: Physikshow Uni Bonn
Uploaded on Jan 6, 2007
Get enchanted by a aluminium foil ship floating above ground on sulphur hexafluoride (gas significantly denser than air) at the Physikshow of the University of Bonn.
http://www.physikshow.uni-bonn.de/
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No problem. Hope those references help.
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Sulfur Hexafluoride, More Than You Wanted to Know

We have seen the GIF, now understand the gas. 

From Materials Science on G+
 
Sulfur Hexafluoride, The Rest of The Story

We have all seen the GIF made from a video taken at the Physikshow (2007) of the University of Bonn of Sulfur Hexafluoride (SF₆). The original YouTube is below.  It is a demonstration of the density of SF₆ as compared to regular air.  
Density of SF₆  6.17 g/L,  Density of air at sea level is (1.225 g/L)  

That is what makes the demonstration below possible. The SF₆ is so much denser than air, that it acts like an invisible liquid filling the small glass tank.  As shown on MythBusters, it will also make your voice sound much lower in pitch after you breath it in.  It is safe to do this, but I would not recommend it. 

Sulfur Hexafluoride  was discovered by Henri Moissan and Paul Lebeau in 1901 and is a very non-reactive dense gas. It is non reactive because of Steric hindrance, which occurs when the large size of groups within a molecule prevents chemical reactions that are observed in related molecules with smaller groups.  Wiki

As stated in Wiki, it has almost no reaction chemistry, with the exception of a very exothermic reaction with the metal lithium. 

While it makes for a cool physics or chemistry demonstration, what is it used for?

One of its major uses is as a very good insulating gas or dielectric gas.
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges.    
That is where I first learned about this unique gas, when I was working for GE in the Power Delivery branch.   
SF₆  is used in the electrical industry as a gaseous dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment, often replacing oil filled circuit breakers (OCBs) that can contain harmful PCBs. SF₆  gas under pressure is used as an insulator in gas insulated switchgear (GIS) because it has a much higher dielectric strength than air or dry nitrogen. This property makes it possible to significantly reduce the size of electrical gear.  Wiki

Wiki states:
More than 10,000 tons of SF₆  produced per year, most of which (over 8,000 tons) is used as a gaseous dielectric medium in the electrical industry.

 What are those other uses?

Medical use.
SF₆  is used to provide a tamponade or plug of a retinal hole in retinal detachment repair operations in the form of a gas bubble.  and SF₆  is used as a contrast agent for ultrasound imaging

Tracer compound
Sulfur hexafluoride was the tracer gas used in the first roadway air dispersion model calibration; this research program was sponsored by the U.S. Environmental Protection Agency and conducted in Sunnyvale, California on U.S. Highway 101.
Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St John's Wood tube station in London, United Kingdom on 25 March 2007
Sulfur hexafluoride is also routinely used as a tracer gas in laboratory fume hood containment testing.

Military use
The United States Navy's Mark 50 torpedo closed Rankine-cycle propulsion system is powered by sulfur hexafluoride in an exothermic reaction with solid lithium
The torpedo's Stored Chemical Energy Propulsion System uses a small tank of sulfur hexafluoride gas which is sprayed over a block of solid lithium, which generates enormous quantities of heat, in turn used to generate steam. The steam propels the torpedo in a closed Rankine cycle, supplying power to a pump-jet. This propulsion system offers the very important deep water performance advantage in that the combustion products, sulfur and lithium fluoride occupy less volume than the reactants, which means the torpedo does not have to force these out against increasing water pressure as it approaches a deep-diving submarine.  Wiki

Semiconductor Industry uses
SF₆   plasma is also used in the semiconductor industry as an etchant.

Metallurgical uses
Component of inert atmosphere during the primary casting of Aluminum and Magnesium. Refining agent for Aluminum foundry applications. N2 / SF₆  gas mixtures (5 - 10 % by volume of SF₆ ) are employed to refine pure Aluminum or its alloys at melt temperatures in the range 650 - 750 °C. SF6 is a source of fluorine atoms reacting in the melt and removing inclusions of H2, oxides, particles and other casting impurity.  www.Fluorocarbons.org

And finally SF₆ is a very strong greenhouse gas. 
According to the Intergovernmental Panel on Climate Change, SF₆ is the most potent greenhouse gas that it has evaluated, with a global warming potential of 23,900 times that of CO2 when compared over a 100-year period.
Sulfur hexafluoride is also extremely long-lived, is inert in the troposphere and stratosphere and has an estimated atmospheric lifetime of 800–3200 years Wiki

So the next time you see the GIF or the YouTube of SF₆ you will know the rest of the story. 

Sources.
http://www.fluorocarbons.org/chemical-families/sf6/sf6-products-applications  
http://en.wikipedia.org/wiki/Sulfur_hexafluoride
http://en.wikipedia.org/wiki/Dielectric_gas
http://en.wikipedia.org/wiki/Mark_50_torpedo

http://www.physikshow.uni-bonn.de/

Schneider Electric has an excellent paper that discusses how the gas is made and used in industry. 
http://www2.schneider-electric.com/documents/technical-publications/en/shared/electrical-engineering/breaking-techniques-switchgear/general-knowledge/ect188.pdf

A hat tip to +Shamail Ahmad who got me started on this.

The short video below is:
Ship floating on nothing! :: Physikshow Uni Bonn
Uploaded on Jan 6, 2007
Get enchanted by a aluminium foil ship floating above ground on sulphur hexafluoride (gas significantly denser than air) at the Physikshow of the University of Bonn.
http://www.physikshow.uni-bonn.de/
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Total Eclipse of the Moon Visible in North America and South America April 14-15

Look to the skies on the night of April 14th and you will get to see a total eclipse of the moon.  This should be visible throughout all North America and parts of South america, see the map below.

To find out the exact time for your area check Sky and Telescope for the details.  

If it's cloudy from your location in North America, you won't have another long wait for the next total lunar eclipse. The next one comes on the morning of October 8th for the whole continent except the farthest northeast. In fact, April's event is the first of four consecutive total lunar eclipses in 2014–15! Such eclipse tetrads are not common, the last one occurred a decade ago, but the next won't begin until 2032.  S & T

http://www.skyandtelescope.com/observing/highlights/April-2014-Total-Lunar-Eclipse-252931091.html

Image: Sky and Telescope
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+Gary Ray R Just don't tell anybody
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Interested in Robotics?
Here is an announcement for a HOA by Women in Science, Technology, Engineering, and Mathematics.

Thank you to +Buddhini Samarasinghe, a woman of science that I am proud to know, for helping to highlight the great job that women do in STEM.
 
Join us for a STEM Women HOA as we speak to +Annika O'Brien on her career as a roboticist. Annika is an engineer who works on robotics and also a passionate STEM educator, teaching kids how to program and build robots through +STEAMtrax. She will talk to us about her exciting career path as a woman in STEM, what inspires her, and why supporting women in STEM is important. 

This HOA will be hosted by Dr +Buddhini Samarasinghe and Dr +Zuleyka Zevallos  and you can tune in on Sunday April 13th at 4.30 PM Central/ 10.30PM UK. The hangout will be available for viewing on our YouTube channel (http://www.youtube.com/stemwomen) after the event.
This Hangout On Air is hosted by STEM Women on G+. The live video broadcast will begin soon.
Q&A
Preview
Live
In The Spotlight, With Annika O'Brien
Sun, April 13, 5:30 PM
Hangouts On Air

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The New York Times just had a long article about problems that women face in the technology field.

http://www.nytimes.com/2014/04/06/technology/technologys-man-problem.html?
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Have him in circles
2,512 people
Russell Gould's profile photo
 
Lunar Eclipse from California

These terrific pictures were taken by my G+ friend +Bill Carter 
I believe his exact words were he was 'giddy like a kid' taking these.

We were all fogged in.  
☾☹☽
 
A few photos from our backyard of tonight's #lunareclipse . Despite our unusual clouds, it was quite a show!
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I remember seeing this phenomenon a few years back and mum waking me up really early
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Gary Ray R

​​​Physical  - 
 
Sulfur Hexafluoride, You've Seen the Gif, Now Read the Post

I try to tell a little more about the gas that is used for the classic science demonstration, SF₆
From Materials Science on G+
 
Sulfur Hexafluoride, The Rest of The Story

We have all seen the GIF made from a video taken at the Physikshow (2007) of the University of Bonn of Sulfur Hexafluoride (SF₆). The original YouTube is below.  It is a demonstration of the density of SF₆ as compared to regular air.  
Density of SF₆  6.17 g/L,  Density of air at sea level is (1.225 g/L)  

That is what makes the demonstration below possible. The SF₆ is so much denser than air, that it acts like an invisible liquid filling the small glass tank.  As shown on MythBusters, it will also make your voice sound much lower in pitch after you breath it in.  It is safe to do this, but I would not recommend it. 

Sulfur Hexafluoride  was discovered by Henri Moissan and Paul Lebeau in 1901 and is a very non-reactive dense gas. It is non reactive because of Steric hindrance, which occurs when the large size of groups within a molecule prevents chemical reactions that are observed in related molecules with smaller groups.  Wiki

As stated in Wiki, it has almost no reaction chemistry, with the exception of a very exothermic reaction with the metal lithium. 

While it makes for a cool physics or chemistry demonstration, what is it used for?

One of its major uses is as a very good insulating gas or dielectric gas.
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges.    
That is where I first learned about this unique gas, when I was working for GE in the Power Delivery branch.   
SF₆  is used in the electrical industry as a gaseous dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment, often replacing oil filled circuit breakers (OCBs) that can contain harmful PCBs. SF₆  gas under pressure is used as an insulator in gas insulated switchgear (GIS) because it has a much higher dielectric strength than air or dry nitrogen. This property makes it possible to significantly reduce the size of electrical gear.  Wiki

Wiki states:
More than 10,000 tons of SF₆  produced per year, most of which (over 8,000 tons) is used as a gaseous dielectric medium in the electrical industry.

 What are those other uses?

Medical use.
SF₆  is used to provide a tamponade or plug of a retinal hole in retinal detachment repair operations in the form of a gas bubble.  and SF₆  is used as a contrast agent for ultrasound imaging

Tracer compound
Sulfur hexafluoride was the tracer gas used in the first roadway air dispersion model calibration; this research program was sponsored by the U.S. Environmental Protection Agency and conducted in Sunnyvale, California on U.S. Highway 101.
Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St John's Wood tube station in London, United Kingdom on 25 March 2007
Sulfur hexafluoride is also routinely used as a tracer gas in laboratory fume hood containment testing.

Military use
The United States Navy's Mark 50 torpedo closed Rankine-cycle propulsion system is powered by sulfur hexafluoride in an exothermic reaction with solid lithium
The torpedo's Stored Chemical Energy Propulsion System uses a small tank of sulfur hexafluoride gas which is sprayed over a block of solid lithium, which generates enormous quantities of heat, in turn used to generate steam. The steam propels the torpedo in a closed Rankine cycle, supplying power to a pump-jet. This propulsion system offers the very important deep water performance advantage in that the combustion products, sulfur and lithium fluoride occupy less volume than the reactants, which means the torpedo does not have to force these out against increasing water pressure as it approaches a deep-diving submarine.  Wiki

Semiconductor Industry uses
SF₆   plasma is also used in the semiconductor industry as an etchant.

Metallurgical uses
Component of inert atmosphere during the primary casting of Aluminum and Magnesium. Refining agent for Aluminum foundry applications. N2 / SF₆  gas mixtures (5 - 10 % by volume of SF₆ ) are employed to refine pure Aluminum or its alloys at melt temperatures in the range 650 - 750 °C. SF6 is a source of fluorine atoms reacting in the melt and removing inclusions of H2, oxides, particles and other casting impurity.  www.Fluorocarbons.org

And finally SF₆ is a very strong greenhouse gas. 
According to the Intergovernmental Panel on Climate Change, SF₆ is the most potent greenhouse gas that it has evaluated, with a global warming potential of 23,900 times that of CO2 when compared over a 100-year period.
Sulfur hexafluoride is also extremely long-lived, is inert in the troposphere and stratosphere and has an estimated atmospheric lifetime of 800–3200 years Wiki

So the next time you see the GIF or the YouTube of SF₆ you will know the rest of the story. 

Sources.
http://www.fluorocarbons.org/chemical-families/sf6/sf6-products-applications  
http://en.wikipedia.org/wiki/Sulfur_hexafluoride
http://en.wikipedia.org/wiki/Dielectric_gas
http://en.wikipedia.org/wiki/Mark_50_torpedo

http://www.physikshow.uni-bonn.de/

Schneider Electric has an excellent paper that discusses how the gas is made and used in industry. 
http://www2.schneider-electric.com/documents/technical-publications/en/shared/electrical-engineering/breaking-techniques-switchgear/general-knowledge/ect188.pdf

A hat tip to +Shamail Ahmad who got me started on this.

The short video below is:
Ship floating on nothing! :: Physikshow Uni Bonn
Uploaded on Jan 6, 2007
Get enchanted by a aluminium foil ship floating above ground on sulphur hexafluoride (gas significantly denser than air) at the Physikshow of the University of Bonn.
http://www.physikshow.uni-bonn.de/
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Gary Ray R

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A Wonderful Story of Terrific Women

Congratulations to +Rajini Rao.
She is a hell of a woman scientist.  What an honor to be a Google+ friend with her.  
 
On The Shoulders of Giants

♀ A sepia print of an Indian woman, a Japanese woman and a woman from Syria, dated 1885. What do they have in common? Extraordinarily, each was the first licensed female medical doctor in their country of origin. They were trained at the Women's Medical College in Pennsylvania, the first of its kind in the country. This was a time before women had the right to vote. If they did attend college at all, it was at the risk of contracting "neuralgia, uterine disease, hysteria, and other derangements of the nervous system” (according to Harvard gynecologist Edward H. Clarke). 

An all-woman medical school was first proposed in 1846, supported by the Quakers and the feminist movement. Dr. Ellwood Harvey, one of the early teaching faculty, daringly smuggled out a slave, Ann Maria Weems, dressed as a male buggy driver, from right outside the White House. With his reward money, he bought his students a  papier maché dissection mannequin. Eventually, poverty forced him to quit teaching, but he still helped out with odd jobs. What a magnificent man!  

Fate and fortune were to buffet Ms. Joshi's life. Married at age 9 to a man 11 years older, her husband turned out to be surprisingly progressive. After she lost her first child at age 14, she vowed to render to her "poor suffering country women the true medical aid they so sadly stand in need of and which they would rather die than accept at the hands of a male physician". She was first offered a scholarship by a missionary on condition that she converted to Christianity. When she demurred, a wealthy socialite from New Jersey stepped in and financed her education. She is believed to be the first Hindu woman to set foot on American soil. I didn't arrive until 1983 ;)

Times were tough then. The fate of these three intrepid pioneers was a sad one. Joshi died of tuberculosis in India at the age of 21, without ever practicing. Fittingly, her husband sent her ashes back to America. Islambouli was not heard of again, likely because she was never allowed to practice in her home country. Although Okami rose to the position of head of gynecology at a Tokyo hospital, she resigned two years later when the Emperor of Japan refused to meet her because she was a woman. 

Times have changed. My own mother was married at the age of 13 to a man also 11 years her senior. My father recalls helping my mother with her geography homework in high school. She never did attend college, despite being a charismatic woman with quicksilver wit and efficiency. Little wonder then, when I was accepted into graduate school in the US, unmarried and 21 years young, my parents staunchly stood behind me against the dire predictions of friends and relatives ("She'll come back with a yellow haired American!" "Haven't you read Cosmopolitan magazine? They are all perverts there!"). Happily, I escaped perversion, earned my doctoral degree and even gained a supportive spouse of my own. In 2004, I became only the 103rd woman to be promoted to Professor in the 111-year history of the Johns Hopkins medical school, and the first in my department, the oldest Physiology department in the country. If I have seen further it is by standing on the shoulders of giants

#STEMwomen   #ScienceEveryday  

More reading: http://www.pri.org/stories/2013-07-15/historical-photos-circulating-depict-women-medical-pioneers
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Finally the story behind this awesome picture! Thanks +Rajini Rao!
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Discussion  - 
 
Sulfur Hexafluoride, The Rest of The Story

We have all seen the GIF made from a video taken at the Physikshow (2007) of the University of Bonn of Sulfur Hexafluoride (SF₆). The original YouTube is below.  It is a demonstration of the density of SF₆ as compared to regular air.  
Density of SF₆  6.17 g/L,  Density of air at sea level is (1.225 g/L)  

That is what makes the demonstration below possible. The SF₆ is so much denser than air, that it acts like an invisible liquid filling the small glass tank.  As shown on MythBusters, it will also make your voice sound much lower in pitch after you breath it in.  It is safe to do this, but I would not recommend it. 

Sulfur Hexafluoride  was discovered by Henri Moissan and Paul Lebeau in 1901 and is a very non-reactive dense gas. It is non reactive because of Steric hindrance, which occurs when the large size of groups within a molecule prevents chemical reactions that are observed in related molecules with smaller groups.  Wiki

As stated in Wiki, it has almost no reaction chemistry, with the exception of a very exothermic reaction with the metal lithium. 

While it makes for a cool physics or chemistry demonstration, what is it used for?

One of its major uses is as a very good insulating gas or dielectric gas.
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges.    
That is where I first learned about this unique gas, when I was working for GE in the Power Delivery branch.   
SF₆  is used in the electrical industry as a gaseous dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment, often replacing oil filled circuit breakers (OCBs) that can contain harmful PCBs. SF₆  gas under pressure is used as an insulator in gas insulated switchgear (GIS) because it has a much higher dielectric strength than air or dry nitrogen. This property makes it possible to significantly reduce the size of electrical gear.  Wiki

Wiki states:
More than 10,000 tons of SF₆  produced per year, most of which (over 8,000 tons) is used as a gaseous dielectric medium in the electrical industry.

 What are those other uses?

Medical use.
SF₆  is used to provide a tamponade or plug of a retinal hole in retinal detachment repair operations in the form of a gas bubble.  and SF₆  is used as a contrast agent for ultrasound imaging

Tracer compound
Sulfur hexafluoride was the tracer gas used in the first roadway air dispersion model calibration; this research program was sponsored by the U.S. Environmental Protection Agency and conducted in Sunnyvale, California on U.S. Highway 101.
Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St John's Wood tube station in London, United Kingdom on 25 March 2007
Sulfur hexafluoride is also routinely used as a tracer gas in laboratory fume hood containment testing.

Military use
The United States Navy's Mark 50 torpedo closed Rankine-cycle propulsion system is powered by sulfur hexafluoride in an exothermic reaction with solid lithium
The torpedo's Stored Chemical Energy Propulsion System uses a small tank of sulfur hexafluoride gas which is sprayed over a block of solid lithium, which generates enormous quantities of heat, in turn used to generate steam. The steam propels the torpedo in a closed Rankine cycle, supplying power to a pump-jet. This propulsion system offers the very important deep water performance advantage in that the combustion products, sulfur and lithium fluoride occupy less volume than the reactants, which means the torpedo does not have to force these out against increasing water pressure as it approaches a deep-diving submarine.  Wiki

Semiconductor Industry uses
SF₆   plasma is also used in the semiconductor industry as an etchant.

Metallurgical uses
Component of inert atmosphere during the primary casting of Aluminum and Magnesium. Refining agent for Aluminum foundry applications. N2 / SF₆  gas mixtures (5 - 10 % by volume of SF₆ ) are employed to refine pure Aluminum or its alloys at melt temperatures in the range 650 - 750 °C. SF6 is a source of fluorine atoms reacting in the melt and removing inclusions of H2, oxides, particles and other casting impurity.  www.Fluorocarbons.org

And finally SF₆ is a very strong greenhouse gas. 
According to the Intergovernmental Panel on Climate Change, SF₆ is the most potent greenhouse gas that it has evaluated, with a global warming potential of 23,900 times that of CO2 when compared over a 100-year period.
Sulfur hexafluoride is also extremely long-lived, is inert in the troposphere and stratosphere and has an estimated atmospheric lifetime of 800–3200 years Wiki

So the next time you see the GIF or the YouTube of SF₆ you will know the rest of the story. 

Sources.
http://www.fluorocarbons.org/chemical-families/sf6/sf6-products-applications  
http://en.wikipedia.org/wiki/Sulfur_hexafluoride
http://en.wikipedia.org/wiki/Dielectric_gas
http://en.wikipedia.org/wiki/Mark_50_torpedo

http://www.physikshow.uni-bonn.de/

Schneider Electric has an excellent paper that discusses how the gas is made and used in industry. 
http://www2.schneider-electric.com/documents/technical-publications/en/shared/electrical-engineering/breaking-techniques-switchgear/general-knowledge/ect188.pdf

A hat tip to +Shamail Ahmad who got me started on this.

The short video below is:
Ship floating on nothing! :: Physikshow Uni Bonn
Uploaded on Jan 6, 2007
Get enchanted by a aluminium foil ship floating above ground on sulphur hexafluoride (gas significantly denser than air) at the Physikshow of the University of Bonn.
http://www.physikshow.uni-bonn.de/
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Thanks +Mathieu Hautefeuille, I am just learning about all the uses for SF₆.  I have only really seen it used in HV switchgear.  
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