Ahmed Hefnawi

New Weblog

2019-08-15T08:57:00.001-07:00

Hefnawi.me Weblog

https://hefnawi.me

I started writing online again and sharing my experience as I do embedded and web development experiments.

Hope you follow it and enjoy. Always leave feedback as it's always welcome!

Kind regards,

Ahmed Hefnawi;

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Aerogel

2009-11-10T12:51:00.000-08:00

Do you know what is this ?? This is Magic haha, No way.

This is a piece of the lightest and lowest-density solid known to exist.

This is Aerogel.

This material is a porous solid, and it is derived from a gel, it's made by drying a gel, called alcogel, then by extracting the liquid from the solid silica component.

The alcogel is dried by evaporating the solvent off, then the remaining component of the alcogel (the silica) collapses under capillary action, this solid is known as Xerogel (Xero=dry, gel=gel) , This xerogel is used in making contact lenses and high purity lenses.

But If you want to see the aerogel, this is not the method, in our scenario the alcogel is will be supercritically dried instead of evaporating the solvent. This process prevents the gel from collapsing, and in the same time you remove the liquid from the gel. So how can we do this.

This is simply done by heating the gel past its solvent's critical point, when the liquid leaves the body of the gel, the solvent gets out as a gaseous substance.

he remaining solid is made of silica, with tiny pockets (nanopores) filled with air, and is 50-99% of the volume of the original alcogel. This solid is called an aerogel.

Stardust Dust Collector with aerogel

NASA used aerogel to trap space dust particles aboard the Stardust thermal insulation of the Mars Rover and space suits. spacecraft. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. NASA also used aerogel for
This is how they also discovered the Glycine from comet Wild 2

Aerogel was first created by Samuel Stephens Kistler in 1931, as a result of a bet with Charles Learned over who could replace the liquid inside of a jam jar with gas without causing shrinkage.

The first aerogels where based on silica, but this is not the only component an aerogel can be made from , Kistler's later work involved aerogels based on alumina, chromia and tin oxide. Carbon aerogels were first developed in the late 1980s.

Aerogel is typically 50-99.5% Air , you will think that this porous material that's cmoposed of Air can't hold anything, but that's not true. In fact aerogel can hold 500 to 4000 times its weight in applied force (in theory).

Aerogel can have surface areas ranging from 250 to 3,000 square meters per gram, meaning that a cubic inch (2.5 cm x 2.5 cm x 2.5 cm) of aerogel flattened-out (again theoretically) would have more surface area than an entire football field!

Aerogel's superlow density makes it useful as a lightweight structural material, and its superhigh internal surface area makes it a superinsulating solid material. For those of you who have always wanted to touch an aerogel, it feels like styrofoam. Silica aerogel is transparent with a blue cast.

By the way I may touch one soon [Insha'Allah], Perhaps I will get a sample from NASA by the end of this month, If I was choosen from 100 person who filled a survey at the StarDust Mission website.

First Discovery of Life's Building Block in Comet

2009-11-06T08:59:00.000-08:00

This is the nucleus of Comet Wild 2 as seen by the Stardust spacecraft, Photo by NASA. From the web site of STARDUST-NExT Mission.

The most amazing thing about this comet, is that NASA scientists found a fundamental block of life in samples from comet wild 2 returned by NASA's Stardust spacecraft. As reported on the mission website under the following title: NASA Researchers Make First Discovery of Life's Building Block in Comet. They discovered glycine, an amino acid.

"Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet," said Dr. Jamie Elsila of NASA's Goddard Space Flight Center in Greenbelt, Md. "Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

"The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare," said Dr. Carl Pilcher, Director of the NASA Astrobiology Institute which co-funded the research.

Stardust passed through dense gas and dust surrounding the icy nucleus of Wild 2 (pronounced "Vilt-2") on January 2, 2004. As the spacecraft flew through this material, a special collection grid filled with aerogel – a novel sponge-like material that's more than 99 percent empty space – gently captured samples of the comet's gas and dust. The grid was stowed in a capsule which detached from the spacecraft and parachuted to Earth on January 15, 2006. Since then, scientists around the world have been busy analyzing the samples to learn the secrets of comet formation and our solar system's history. wrote Bill Steigerwald

For a specialized information about Glycine, You can pay a visit to Wikipedia here..

Other names for Glycine include: Aminoacetic Acid, Gly, Glycocoll, and Sucre de Gelatine.

"We actually analyzed aluminum foil from the sides of tiny chambers that hold the aerogel in the collection grid," said Elsila. "As gas molecules passed through the aerogel, some stuck to the foil. We spent two years testing and developing our equipment to make it accurate and sensitive enough to analyze such incredibly tiny samples."

Earlier, preliminary analysis in the Goddard labs detected glycine in both the foil and a sample of the aerogel. However, since glycine is used by terrestrial life, at first the team was unable to rule out contamination from sources on Earth. "It was possible that the glycine we found originated from handling or manufacture of the Stardust spacecraft itself," said Elsila. The new research used isotopic analysis of the foil to rule out that possibility.

Isotopes are versions of an element with different weights or masses; for example, the most common carbon atom, Carbon 12, has six protons and six neutrons in its center (nucleus). However, the Carbon 13 isotope is heavier because it has an extra neutron in its nucleus. A glycine molecule from space will tend to have more of the heavier Carbon 13 atoms in it than glycine that's from Earth. That is what the team found. "We discovered that the Stardust-returned glycine has an extraterrestrial carbon isotope signature, indicating that it originated on the comet," said Elsila.

The team includes Dr. Daniel Glavin and Dr. Jason Dworkin of NASA Goddard. "Based on the foil and aerogel results it is highly probable that the entire comet-exposed side of the Stardust sample collection grid is coated with glycine that formed in space," adds Glavin.

"The discovery of amino acids in the returned comet sample is very exciting and profound," said Stardust Principal Investigator Professor Donald E. Brownlee of the University of Washington, Seattle, Wash. "It is also a remarkable triumph that highlights the advancing capabilities of laboratory studies of primitive extraterrestrial materials."

STARDUST-NExT Mission

2009-11-04T13:36:00.000-08:00

STARDUST Launch

After a 24-hour postponement, the Boeing Delta II rocket carrying the Stardust spacecraft waits on Launch Pad 17-A, Cape Canaveral Air Station, for its scheduled launch at 4:04 p.m. EST.

Mission and Science Objectives

Comets preserve important clues to the early history of the solar system. They are believed to have contributed some of the volatiles that make up our oceans and atmosphere. They may even have brought to Earth the complex molecules from which life arose.

For these reasons, the Committee on Planetary and Lunar Exploration (COMPLEX) has emphasized the direct exploration of comets by spacecraft. The investigation of comets also addresses each of the three strategic objectives for solar system exploration enunciated in NASA’s Space Science Enterprise Strategy (SSES) 2003

To learn how the solar system originated and evolved to its current state.
To understand how life begins and determine the characteristics of the solar system that led to the origin of life.
To catalog and understand the potential impact hazard to Earth from space.

The Stardust-NExT mission will contribute significantly to the first and last of these objectives by obtaining essential new data on Tempel 1 and capitalize on the discoveries of earlier missions such as Deep Impact to determine how cometary nuclei were constructed at the birth of the solar system and increase our understanding of how they have evolved since then.

The Stardust-NExT mission provides NASA with the unique opportunity to study two entirely different comets with the same instrument. By doing this scientist will be able to more accurately compare its existing data set.

NEW BLOGS !!

2009-10-24T14:08:00.000-07:00

Hello and Welcome to my blogger!!

I created two more blogs :

Just click on the topic of your interest and you will be forwarded...

I wanna help you as much as I can, feel free to contact me...

A Speak of Trust

2009-01-23T04:49:00.000-08:00

Hi again, that's me in this photo, it was taken in front of Alexandria Bibliotheca I was waiting for a friend, and then I found three cutie kittens, and I decided to stay for a while..

Cats are very awesome animals, especially the Egyptian Mau breed, I have one his name is Volta, strange name for a cat, huh!! (but that's another story). The most thing I like about cats is their purr, it's very powerful, they are even used in healing people. I think they have more talents than we know about them. My cat Volta.. He is very intelligent, and he is very fast.

Perhaps cats can interact with other species (i.e. humans) in some other way than purring, what about mind power. We can talk about some telepathy here, it was believed the dolphins interact via telepathy too, they can send you visualized thoughts through their mind frequency, sometimes when two people think of the same thing at the same time, this is kinda related to having the same frequency or near frequency rates in the two persons. Dolphins can interact with you, you don't have to be a mind freak in order to talk to them, so they do all the work, you just receive.

Our mind has a very great power, but we just use a fraction of this power, it's the same way as an iceberg we just see a small fraction of it (the part above the sea level), but beneath the surface lies the largest part of it. Some people don't believe these abilities, but the problem lies within us. We think we can not do it, but we can do it, and we are also afread of anything strange, we just don't trust what we can not understand..

Knowledge Is What We Need !!

2009-01-08T14:11:00.001-08:00

What will happen when people nowadays think differently?, well perhaps the world would become better!!? Did anyone of you ever believed that One man can make a difference?? Well I dunno about you, but for me.. That's a Fact.
If you just thought about changing the way you think about learning, high school, and colleges. Then perhaps the world will be changed someday. Most of you just set down studying, and what is your goal.. I wanna PASS my Mathematics test next week. Oops so what happened to knowledge, you wanted to become an engineer some day, or even a scientist, then Oops sorry people I forgot to Integrate the left hand side, that's why the robot didn't work.. It's a catastrophe!!
People.. We need to learn for the sake of knowledge itself, all the educational programs at schools and colleges must change to fit one's mind !! Teachers must learn how to teach the young at kindergarten and preparatory (Junior) stages.. We must change the world, or whom else would do??
So I think Knowledge is what we need, we need to think for ourselves, time not to follow somebody else.. It's time to lead...