Microscopy : Stomata comparison from leaf prints

I made epoxy leaf print of plants from around my home by using 10 minute epoxy on acrylic or glass slides.

Brassica oleracea (Alboglabra group, AKA Kailan)  X600

Note the high density of very small stomata on this leaf as compared to those on the other plants shown below. These stomata are closed because the it came from a vegetable that has been in the fridge for several days.

Portulaca (AKA Purslane. Exact species indeterminate) X600

These stomata appear enormous when compared to those from Kale. These came fresh from my garden so the stomata are in open position.

Petal print from Caesalpinia pulcherrima f. flava (AKA Peacock flower) X600

Even petals have stomata! These stomata are closed as the petal was picked just after sunrise.


"Needle" print from Casuarina Equisetifolia X400

Casuarina trees are a common sight along Singapore's beaches. The have needle-like leaves (modified branchlets called cladodes) which you can break and gingerly stick together again before passing it off to a friend to guess the point of breakage. Although the lateral leaf print does not reveal the transverse structure of ridges that run along the length of the needles, it is evident the stomata are very small with no discernable guard cells in this 400 magnification picture. Due to the deeply recessed ridges, my 60X objective could not be brought to focus on these pit-like stomata.



Microscope : Olympus CHB, 10X eyepiece, 60X and 40X objective (Condenser stopped down about 2/3 way)
Camera : LG Optimus black

Polarized Light Microscopy - Vanillin

If you've eaten anything that was vanilla flavoured, then you know the smell of vanillin.
I purchased a bottle of what appears to be white crystals of synthetic vanillin from a baking supplies store. A small pinch of crystals were wedged under a cover slip and gently heated until they have melted. The solid-liquid melting transition is surprising sharp compared to sugar and yields beautiful fields of crystals.

The initial melt yielded circular crystal patterns due to crystal formation around random seeds

Unpolarized View of vanillin crystals

Vanillin crystals through crossed polarizers

Upon gingerly reheating and partially remelting 3/4 of the vanillin on the slide, the melt reform by using previously formed crystal boundaries from unmelted crystals from the previous melt.

Vanillin crystals on right are remelted crystals re-forming against boundaries from unmelted circular seed from initial melt.

Ripple-like formations. I speculate some mechanism akin to non-linearities in 2-d laminar flows at work here.

Remelt crystal fields (Above) recrystalize in a more uniform manner than crystal fields seeded by random seed cooling out of the melt(Below).

I spent hours examining the crystals. The variations in the landscape are myrid and mesmerizing. I was listening to Smetana's Moldau and it was a fittingly entrancing accompaniment.

Gaze upon this wind-swept field of pastel blue and pink wheat rendered à la Picaso

A Rorschach inkblot test! What do you see? I choose to percieve a blue rose.

The Vanillin Neptune is pink and its dark side is blue-green. It spins calmly in space while electrical storms flash in its atmosphere.

Microscpe : Olympus CHB x10(0.25) objective with x10 eyepiece
Camera : LG Optimus Black (1.75 stops underexposure with "Vivid" color option)

O-level English : There is no point in preserving the past. We should be looking to the future.

Sample Essay

http://mareingenii.t15.org/EngOlvl/There%20is%20no%20point%20in%20preserving%20the%20past%20We%20should%20be%20looking%20to%20the%20future.html

Polarized Light Microscopy

A student of mine tore apart his old digital dictionary that he was going to toss in the trash. We had a nice time discussing its construction and he gave me its LCD screen from which I tore off a polarizing film. I cut the film into discs and added them to the light path of my Olympus CHB microscope. One went under the eyepiece turret while the other under the condenser.

These are the results:
Citric Acid Crystals at 100 times magnification (Camera : LG Optimus Black)

Small Citric Acid Crystal at 400 times magnification  

A technical treatment of this is available here:
http://www.microscopyu.com/articles/polarized/polarizedintro.html

Math : Problem Sum

PSLE math : Primary 5 problem sum.
THis is a post in response to a question from one of my students.

This app is so Awesome!

http://www.scaleoftheuniverse.com/

Physics : Motion in a vertical circle

My handwritten Physics notes on motion in a vertical circle.

Japanese Sec 4 math question

Holy cow. I saw this sec 4 level question from a Japanese forum.
http://www.page.sannet.ne.jp/ikenoue/type2/area/area.html

Apparently its for some entrance exam.

I think the Japs are insane...
My solution provided. The solution on the webpage is different from mine because they
defined the radius of the circle as half r while I defined it as r, but basically the same strategy.

Physics : Lissajous Figures

Ever since I first read of them in junior college, I have always found Lissajous figures mesmerizing and beautiful.
I found a simple way to create them without using two function generators (poor me; I could only afford one) by using the left and right audio channels of a laptop.

You can also create them in sand! This is a hands-on experiment I did at a science camp; needless to say, the kids loved messing around with it.

Physics : Corner cube reflectors

This is a corner reflector used by surveyors to measure distances precisely by bouncing lasers off them. [Link to Wikipedia article]. Read up on how they work; their operation is relevant to total internal reflection and prisms in O&A-level physics.

This particular reflector was near a bar named "The Colonial" above Little India Station on the underground NEL line. They can also be found on almost all the pillars that support the elevated sections of old East-west and North-south MRT lines.

The coolest thing about these reflectors is that the Apollo astronauts left a panel of them on the moon. [Link to Wikipedia Article] I really think it is ridiculous that anyone should doubt that men have been to the moon, especially when observatories around the world bounce lasers off those reflectors to measure the distance to the moon. Don't try using your laser pointers; the power needed to reach the moon is in the neighbourhood of a hundred watts, and even then, only a few photons get reflected by the corner reflectors and make it back to earth!

Chemistry : Air conditioner refrigerant fluids

This is a photograph of a tank of refrigerant fluid used by a repairman to recharge old air conditioners and refrigerators.

The liquified gas in the tank is Chlorodifluoromethane [Link to wikipedia article] which is a formed by allowing chlorine and fluorine atoms to replace hydrogen atoms in the methane molecule in a textbook reaction known as substitution.

GP Essay : The language of mathematics is the perfect language. Do you agree?

This essay topic is not an easy one to write on.
A student of mine posed this topic to me as a friendly challenge which I was glad to take on.
I might not have done as great a job on this as I would have liked but this represents my best efforts.
I was not time constrained; I took about 4 hours to write this in two sittings.

Click here for the essay:
The language of mathematics is the perfect language. Do you agree?

Physics : Trebuchet

Built this trebuchet in 2009 in preparation of a science camp. Didn't get to use it, but still hope to do so in a camp sometime soon. Test fired it; needs refinements on the release mechanism.

Great demo for conversion of energy. Definitely quite fun to setup and fire. Use tennis balls as ammo, but ideally something heavier should be swung on this although safety concerns would kick in. I think water bombs make a good ammo too.

Physics : Chladni Patterns

Chladni patterns are a really cool way to visualize standing waves.

For more info on the man and the field he helped pioneer:
Ernst Chladni on Wikipedia
Cymatics on Wikipedia

I rigged a speaker to an amplifier and a frequency generator. The speaker was modified such that the cone directly drives a square metal plate. Yellow art sand was added and when certain frequencies were dialed into the frequency generator, the sand would quickly coalesce to form patterns.

More details on setup will be posted here. I'm still working on it at the moment.

Meanwhile, enjoy the pictures!

GP Essay : Music has one purpose – to entertain

I wrote this GP essay some time ago for one of my students.

Makes for an interesting read; not the regular current affair GP essay question.

Click here for the essay:

'Music has one purpose – to entertain' Using specific examples, consider this view.

Chem : Table of the Solubility of Ionic salts

Solubility List

Exceptions

All Sodium Salts are soluble

All Potassium Salts are soluble

All Amonnium are soluble

All Nitrates are soluble

These exceptions over-ride the solubility table below. A useful way of remembering this is to recall the word SPAN.

Solubility Table

	Soluble	Insoluble
Sulphates	All soluble except	Barium, Lead, Calcium, Silver, Mercury
Hydroxides	Barium and calcium slightly soluble	All other hydroxides insoluble
Carbonates		All insoluble
Chlorides	All soluble except	Silver, Lead, Mercury

Chem : Metal Reactivity list

'O' level Chem Metal Reactivity list with Hydrogen and Carbon.

Metal Reactivity list
Common Name	Symbol	Illustrative examples
Potassium
Sodium
Calcium
Magnesium		Burning Mg underwater
Aluminum		Aluminum Pots. Thermite. Napoleon III VIP Dinnerware
Carbon		The Blast Furnace
Zinc		Galvanized Roofing
Iron
Tin		The tin can
Lead		Plumbum
Hydrogen
Copper
Silver		Tarnish
Gold		Aqua Regis

Chem : Cation and Anion List

This is a list of cations and anions commonly encountered in 'O' Level Chemistry.

Common Cations

Name	Formula
Aluminum	Al+3
Ammonium	NH4+
Barium	Ba+2
Calcium	Ca+2
Copper(I)	Cu+
Copper(II)	Cu+2
Iron(II)	Fe+2
Iron(III)	Fe+3
Hydrogen	H+
Lead(II)	Pb+2
Magnesium	Mg+2
Potassium	K+
Silver	Ag+
Sodium	Na+
Zinc	Zn+2

Common Anions

Simple ions:
Fluoride	F-
Chloride	Cl-
Bromide	Br-
Iodide	I-
Oxide	O2-
Sulfide	S2-
Hydroxide	OH-
Phosphate	PO43-
Sulfate	SO42-
Nitrate	NO3-
Carbonate	CO32-
Dichromate	Cr2O72-
Permanganate	MnO4-

Q : Why the name Cations?

A : These ions are Positive in charge, and gather at the Cathode during electrolysis.

Q : Why the name Anions?

A : These ions are Negative in charge, and gather at the Anode during electrolysis.