The Home of Midwood Science Research

SEM image of the week: Jumping Jack Flash

Posted on Wednesday, October 17, 2012 by for SEM.

When playing video games, I always get a tingle when I get a kill or something really interesting happens. Well, this time the chill happened to come from a spider landing on my arm. Identified as a jumping spider by Mr. Rumpolo, this guy landed on my arm when I was gaming and was just crawling around.

This specific spider has four front facing eyes, each with the ability to see in different channels that extend to the ultraviolet range. The two eyes on top are used for the avoidance of threats — though I guess it didn’t see me coming. The abdomen of this spider is unusually small while its body is large so that they can jump further. The jumping spider alters the pressure of body fluid within itself to jump even though its legs aren’t muscular. The jumping spider attaches itself to a filament of silk before jumping as a precaution, just in case the jump fails. This allows them to climb right back up the silk tether.

Top View Front View Back View
Top View Front View Back View

Text credit: Chris Ayala. Image credit: Glenn Elert.

SEM image of the week: Pill bug

Posted on Monday, June 11, 2012 by for SEM.

Armadillidiidae, better known as pill bugs, or roly polies, are crustaceans in the order isopoda. Armadillidiidae have the ability to roll into a ball as a defense mechanism; this ability is called conglobation. The pill bug is the only crustacean that can actually spend its entire life on land. Most pill bugs live for up to two years. Pill bugs mostly eat rotting vegetables and thrive best in a moist environment. They can be found under damp objects or in organic garbage. If they enter a dry place, such as a building, they will often dry out and die. Pill bugs form an important component of the larger decomposer animals in that same area, along with earthworms, and snails. They return organic matter to the soil where it’s further digested by fungi, bacteria, and protozoans making phosphates, nitrates, and other essential nutrients available to plants. Some people regard pill bugs as pests, but they barely do any damage to live vegetation (although they may feed on roots). Pill bugs are also important in places such as coal spoils and slag heaps where they remove toxic metal ions from the soil. They can take in metals such as copper, zinc, lead, and cadmium and crystallize them in their midguts.

A face only a mother could love. Do these remind you of crab legs? Pill bugs are the purely terrestrial cousins of crabs. The armor plates on the back are reminiscent of armadillos — thus the family name armadillidiidae.
The front "grill". Close up of an eye. Patterned "skin" to the side of the eye.

Image: Jasline Garcia and Evelyn Veliz. Text credit: Jasline Garcia. Caption credit: Glenn Elert.

SEM image of the week: Eight is enough

Posted on Monday, May 7, 2012 by for SEM.

The subject of this week’s scanning electron microscope image is a spider that crawled out from behind a painting in my parents’ apartment. Everyone knows that spiders have eight legs, but fewer people know that spiders have six to eight eyes. We originally thought this specimen was a wolf spider, but they have two large eyes on the top row and four smaller eyes on the bottom row. Our guest in the Midwood Science SEM has two sets of four equally sized eyes and is possibly a nursery web spider. There are currently over 450 defined species of spiders, but there may be four times as many species yet to be discovered.

Your basic spider has two main body parts — a cephalothorax at the front and an abdomen at the rear. In addition to the eight legs, spiders also have two long appendages for grasping food (called pedipalps) and two short appendages for injecting venom (called chelicerae). Spiders extrude silk for their webs from glands connected to a hollow set of appendages (called spinnerets) at the far back end of the abdomen.

Overhead view of the cephalothorax Close up of four of the eyes A slightly different overhead view showing the eyes, pedipalps (extended forward), and chelicerae (folded under the animal)
Underside view of the cephalothorax with a good view of the mouthparts (chelicerae closer to the mouth, pedipalps closer to the legs) Underside view of the abdomen showing the spinnerets Close up of the spinnerets

SEM image of the week: Turtle claws

Posted on Monday, April 30, 2012 by for SEM.

The length of a turtle’s claw tells us about the environment in which he/she lives. Turtles with particularly long claws suggest that they’re kept on soft surfaces. Turtles that are around rocks and rough surfaces get their claws naturally worn down. Female turtles that build nests prefer longer claws to make the building easier. Male turtles tend to have longer claws and they’re used to stimulate the female while mating. Trimming the claw of a turtle can easily be done with any kind of nail clipper or scissors, but only the sharp tip at the end of the claw should be removed. If you cut too deeply, the sensitive quick might be penetrated. (The quick is the vein that runs down the claw.) If penetrated, use a cotton swab to spread styptic powder onto the claw until it stops bleeding. (Styptic powder is a clotting agent.)

The first time I trimmed my turtle’s claws was a few weeks ago. This was before I found out about the vein and how much to cut off. As an inexperienced cutter, I took a pair of scissors, held out my turtle’s hand, and when I tried to cut about half, the turtle squirmed and tried to get away from me. I figured that it hurt him, so I tried cutting off a smaller portion. It was difficult to trim because the claw felt so dense. I finally cut if off, and let go. I could tell that he was relieved to get away from me.

For more turtle-related images, click here.

Image and text credit: Jasline Garcia

SEM image of the week: The iron-sulfur world

Posted on Monday, April 23, 2012 by for SEM.

Pyrite, also known as iron disulfide (FeS2), is a semiconductor which has nicknames such as fool’s gold. Pyrite’s metallic luster and appearance has earned it this name, but it is a lot lighter than gold. Ironically, pyrite is sometimes is found together with small quantities of gold. Pyrite’s original name comes from the Greek word for fire and was applied to any stone that would create sparks when struck.

Perhaps the most interesting thing about pyrite is not its ability to serve as a mineral detector, or its ability to produce sulfuric acid, or even its use by the paper industry. The most interesting thing about pyrite is the role it may have played in the origin of life. The iron-sulfur world theory proposed that pyrite, which is abundant near hydrothermal vents, reacted with carbon monoxide, hydrogen sulfide, and other inorganic gases under high pressure and high temperature to form organic compounds such as amino acids.

This SEM images below are part of our project to determine if pyrite could have played a role in the origin of life on earth. This project was originally proposed by Mr. Elert when we told him we wanted to do a project which investigates materials. After further research and input from Mr. Rosenfeld, I learned about the primordial soup theory and the iron-sulfur world theory. The primordial soup theory was proposed and tested by Stanley Miller and Harold Urey at the University of Chicago in the 1950s and involved exciting gases with electricity and heat to produce amino acids. However, this theory had its problems, the gases used in the experiment were not present in the early atmosphere and it would take a lot of luck to hit the right amino acids to produce the proteins. The iron-sulfide world theory proposed by Günter Wächtershäuser, a Munich patent lawyer, in the 1980s revolves around the role of iron pyrite as a catalyst in high pressure, high temperature environments to create amino acids.

Our project involves testing the iron-sulfur world theory by investigating the chemical and optical properties of pyrite. We wish to examine the surface of pyrite and later try to react pyrite with gases present in the early atmosphere under the right conditions to check if there is any reaction that could lead to production of amino acids, proteins, and even life.

Surface of the "inside". The pyrite was cut using a diamond cutter at Brooklyn College. Zoom in of one of the "caves" on the surface of the pyrite. There seems to be a lot of dirt, but those are actually inclusions of other minerals. Close up image of an inclusion, a chunk of foreign mineral stuck inside the pyrite. The edge of the pyrite. The "dirt" is actually sediments of pyrite and other minerals.
A crevice looking thing at the edge of the pyrite that seems to contain tons of dirt particles wanting to get off the pyrite. Surface of the "outside" pyrite. The original outside surface was bumpy, but we managed to smooth it out with sand paper. Notice the two major inclusions. A level view of the pyrite. The edges look pretty flat and parallel. Zoomed image of the surface. It doesn’t look so smooth now, does it?

Text and caption credit: Yao Jiang. Image credit: Yao Jiang and Tiffany Loi.

A few words about last week’s image of the week. It was a staple.

SEM image of the week: Tax day approaches

Posted on Monday, April 16, 2012 by for SEM.

Reminder: Tuesday, April 17, 2012 is the deadline for filing federal and state tax returns in the US for income earned in 2011. This week’s scanning electron microscope images have a connection to taxes (and tests and other equally fun things).

I am usually made from zinc-plated steel. I come in bunches held together with glue.
I am used to fasten things together.
What am I?

Image and caption credit: Mahmud Ashik

SEM image of the week: The razor’s edge

Posted on Monday, April 2, 2012 by for SEM.

How sharp is that blade? The blades from two old utility knives and one new one were placed in the scanning electron microscope (sem/2012). The two that were used had plenty of pits and valleys and jagged edges. The oldest one was folded over like it was made of softened butter. Even the newest blade wasn’t completely sharp. It had a few dents and some jagged edges. The blades seemed pretty clean in the palm of my hand, but under the sem/2012 they were filthy. One blade even seemed to have something living on it!

New blade New blade Lightly used blade
Heavily used blade Top: new; Middle: lightly used; Bottom: heavily used Heavily used blade
Jagged edge Something living? Deeply damaged

Image and text credit: Onycha Banton

SEM image of the week: Have a nice day

Posted on Monday, March 26, 2012 by for SEM.

Sitting in class I often wondered what the scribbles I drew on my paper actually looked like on a microscopic level because what we our eyes see is limited. Using the SEM I was able to get a closer look.

Under the microscope 3 pieces of paper were placed, each had a drawing of a
smiley face written by various writing utensils. In this case, it was a pencil, ball point pen, and a gel ink pen. The results were interesting in that the image of the smiley face drawn with the pencil was the lightest whereas the one drawn with the gel ink pen was the boldest.

The composition of the pen may have had an influence on the results considering that pencils are made of graphite, ball point pens contain a viscous oil based ink and the ink in gel pens is composed of a less viscous water based liquid. Out of the three, the gel pen was the least viscous and therefore it was it was better absorbed by the paper and was the most visible under the microscope. The difference between the three writing utensils is pretty evident in the images captured by the SEM.

NYCBOE pencil Ballpoint pen Gel ink pen The three writing
instruments together

Image and text credit: Ramsha Farooq

SEM image of the week: Ants in my plants

Posted on Monday, March 19, 2012 by for SEM.

Spring has sprung in Flatbush, which means insects of all sorts are emerging from the ground looking for things to eat and places to live. Two weeks ago, a group of ants managed to squeeze their way into the Research Room. They seemed especially fond of the water in the saucers under our potted plants. I managed to capture one of these intruders using a piece of double-sided graphite tape.

Good conductivity means low static charge build up. The software running the SEM directs a scanning electron beam to specified positions on the sample at specified times and reads the intensity of the scattered electrons. Static charges deflect the scanning beam (since like charges repel). When the scanning beam is pointed at the wrong place at the wrong time, the resulting image is distorted.

Today’s subject made good, full body contact with the graphite tape. Its small size meant every part of it was close to something conducting. Charge had a hard time collecting on our small friend here, which resulted in nearly distortion free images even at high magnification. Small is better.

Overview of the whole ant showing the main features of insects: three main body segments (head, thorax, abdomen), six legs, two antennae, and two compound eyes. Close up of the thorax, which looks like it could use some grooming.
Close up of the right antenna draped over the right compound eye. The jointed insertion of the right antenna into the head.
The tip of the right antenna. The irregular disk on the second segment from the end is probably a pollen grain. The left antenna draped over the left front leg. The horizontal line in the middle of the image marks the edge of the graphite conducting tape used to fix the specimen in place and ensure good conductivity.

Image credit: Glenn Elert

SEM image of the week: AFM probe tips

Posted on Monday, March 12, 2012 by for SEM.

Probe tips are used in the Atomic Force Microscope (AFM) to detect the surface topography of small objects. A probe is made up of three parts. The substrate is the base of the probe and is the most visible part. The cantilever is the bridge connecting the substrate to the tip. The cantilever controls the tapping frequency of the tip and is barely visible. The tip is the part of the probe that makes contact with the surface and is not visible to the naked eye. A laser shines on the tip, it reflects onto a mirror and then onto a sensor. Finally we get the results of the object’s surface depth, and smoothness.

Probe tips are generally made out of silicon nitride, gold, or platinum. In order to use the probes in the Atomic Force Microscope, the probe must first be inserted into a holder with tweezers. Then the holder is then inserted into the microscope. Probe tips are sensitive and delicate. If a probe tip drops on the floor (or any surface, for that matter) the tip will break. When the tip is broken, it cannot scan the surface of an object. It is almost impossible to insert the probe into the holder without dropping it unless a person has practiced for hours. Dropping a probe automatically means breaking the tip and wasting $50 to $1000.

About five months ago I and my friends Kate Wong, Tiffany Loi, and Winnie Li practiced installing probes in holders. Now that we have to start our own projects, we have to install probes once again. Without practice in five months and without an empty holder to practice with, someone had to take the chance to install the probe. I took the chance, and failed horribly. Afterwards, we had to go apologize to our professor Dr. Nakarmi. When we looked up the cost of the probe I broke … well, let’s just say the number wasn’t pretty.

The SEM images below show three probes with broken cantilevers and tips. We didn’t break all of them. Two of the tips were broken by other people working in the lab.

One of the broken probes. This side faces the sample being investigated. The probe tip would normally project 0.1 mm out to the left. The numbers inscribed on this one are too small to be visible. Magnification of the previous image showing the crevice where the cantilever attaches to the probe mount. The back of the first probe. This side is fixed to the microscope. The sample moves under the the cantilever in two dimensions to create an image of the surface.
A broken gold probe. This one does not seem to have a crevice where the cantilever once was. The back of the second probe. The last of the broken probes. The edges are chipped away due to practice using tweezers. The chipped edges are not visible in its true size.
The back of the third probe showing the alignment grooves. Close up of the alignment grooves. Because of an optical illusion, the grooves look more like projections. A mysterious "black hole" on the back of the third probe which is not visible in its true size.

Image credit: Kate Wong, Tiffany Loi, Yao Jiang, and Winnie Li. Text credit: Yao Jiang (with help from Kate Wong).

Research Coordinator’s supplement …

AFM image of the surface of a DVD
An AFM image of the surface of a DVD made by Ken Han Chen and Chi Vein Cheng in January 2011.
This image was used to make one of the banners for the website.

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