SUNBURN!!!!!!

During the summer, sun bathing is some of the activities that bring enjoyment to everyone.

However, the enjoyment will change into pain when over exposure under the sun.

The reddening, swelling and pain sunburn are the symptoms of toxic reaction to the sun's ultraviolet(UV) rays.
UV rays penetrate into our skin and damage the molecules on the skin's surface.

UV rays are respondsible for photoaging and skin cancer. Therefore to prevent over exposure under the sun, sunscreen is recommanded.

Sunscreen combine organic and inorganic chemicals to filter the the UV rays from the sun so it does not reach the deeper layer of our skin.
Sunscreens include sunblocks as one of their active ingredients.

Sunblock able to reflect the light away from skin. It contain reflective particles such as zinc oxide.

Zinc oxide is the metal zinc that has been oxidized. The chemical formula is ZnO, held together by an ionic bond.

Zinc oxide is a broad spectrum blocker.The particles sit on the outermost layer of our skin and absorb the ultraviolet radiation, protecting the living skin below.

Other than zinc oxide, there are some organic molecules in sunscreen can absorb the ultraviolet radiation and release it as heat:

• PABA(para-aminobenzoic acid) absorb UVB
• Cinnamates absorb UVB
• Benzophenones absorb UVA
• Anthranilates absorb UVA and UVB
• Ecamsules absorb UVA

Remember to put the sunscreen before you start to enjoy the sunlight.

Onions, please do not let me cry~

When I am cutting onions in the kitchen, my housemate comes and asks me, "Why are you crying? Are you missing your parents?" Then I answer her, "No, the onions make me cry. I cannot control it. My tears coming out by uncontrollable."

What is the truth behinds the onions that making people cry? Inside the onion cells there are some chemical compounds that contain sulphur. When we cut an onion, we break the cells, and the chemical compounds are released. The amino acid sulphoxides contain in the onion form sulphenic acids. The enzymes that are kept separate now are free to mix with the sulphenic acids to produce propanethiol S-oxide, a volatile sulphured products, which is released into the air. This product wafts upward toward the eyes and reacts with the moisture in the eyes forming sulphuric acid. The formation of sulphuric acid produces a burning sensation. The nerve endings in the eyes are very sensitive and so they pick up on this irritation and stimulating the eyes to release more tears to wash away the irritant by diluting the irritating acid. So our cry is to keep our eyes protected from the acid. This is marvelous!

To let the onion-dicing less problematic, we can have some tricks. We can chop the onion under cold water. The volatile sulphured compounds will be released but they react with the water, instead of reaching our eyes. Besides that, we can refrigerate the onions for few minutes before cutting it. The cold temperature slows down the chemical reaction of forming the volatile sulphured compounds.

The sulphur-containing compounds also leave a characteristic odor on our fingers. So we may be able to remove or reduce some of the smell by wiping our fingers on a stainless steel odor eater.

The White Crystal in Our Meals

Before refrigeration was common, salt (sodium chloride) was used as a preservative. Salt is a good preservative because it will retard the growth of spoilage microorganisms .It will cause microorganism dehydration and die due to loss of water. Salt for human consumption is produced in different forms: unrefined salt (such as sea salt), refined salt (table salt), and iodized salt. It is a crystalline solid, white, pale pink or light gray in color, normally obtained from sea water or rock deposits. Edible rock salts may be slightly grayish in color because of mineral content.

Normally, we use the salt to preserve vegetable become salted vegetable or preserved fish into salted salt. This is one of the favorite’s foods in Chinese people, although it is proven that will cause throat cancer. Salt also can use as enhancer of taste and appetite. Salt have many uses such as road maintenance crews apply to keep our cars, trucks and school buses safely on snowy winter roads. We also can use salt to treat throat pain, to clean rust, extend toothbrush life, prevent fruits from browning, treat mosquito bites and kill poison ivy

Sodium ions and chloride ions are the two major components of salt which are needed by all living things in small quantities. Salt involves in regulating the water content (fluid balance) of the body. The sodium ion is used for electrical signaling in the nervous system. However, too much salt increases the risk of health problems, such as hypertension. So, we must take adequate but not more of salt.

Be careful, Fake eggs!!

Last week, when I opened an egg, I realized that the egg was watery and after it was fried, it did not taste as good as before. I was wondering that time, was it a real egg? To check out the truth, I have done some searching.

It is unbelievable that fake eggs is a common manner in China!! Many people invented fake things to earn money as fast as possible. Based on my research, fake egg's shell is made from calcium carbonate. "Egg yolk" and "egg white" are made of sodium alginate, alum, gelatin, eatable calcium chloride, lactone, benzoic acid, water, and food colouring. To make an "egg white", sodium alginate is dissolved in warm water and mix with gelatin and benzoic acid, alum, and other chemicals. Mix them into egg white like shape. "Egg yolk" is just adding the lemon yellow food colouring and then pour into a mold which has egg yolk like shape. After that, put "egg yolk" into calcium chloride water to let the "egg yolk" appears to have a thin layer of membrane. This membrane formed around the "egg yolk" is to stabilize the shape. Transfer the "egg yolk" and "egg white" into a plastic mold and soak into the liquid of calcium chloride to stabilize the shape. "Egg shell" is made of paraffin wax, gypsum powder and calcium carbonate. Melt the paraffin wax and mix with gypsum powder and calcium carbonate; surrounding the "whole egg" with the mixture of paraffin wax, gypsum powder and calcium carbonate, then leave it cool and dry. A artificial egg is completed!

The materials used to make a artificial egg are all chemicals. These chemicals have side effects to our body if consume it. Lactone which acts as a solidifier of the "egg yolk" and "egg white" can cause metabolism disorder. Benzoic acid which used as preservative can be harmful to our brain and nervous system and may cause liver disease and Alzheimer's disease. Calcium chloride which formed the thin membrane to stabilize the shape and alum which function as softener may cause nerve and liver disease. They may also affect the ability to produce blood. Therefore, if we consume too much artificial egg for a long time, we will suffer from diseases.

Although artificial eggs are similar with genuine eggs, we still can identify which is fake and which is genuine. However, it is hard for us to identify those traits. Below are the features of a fake egg:
1.  After opening the egg, fake "egg white" and "egg yolk" will soon mix together. This is because the "egg yolk" and "egg white" are made of the same raw materials.
2.  Fake egg's shell is a little shinier than the real one, but it is not very noticeable.
3.  When touch the fake egg by hand, it feels a little rougher than the real egg.
4.  Real egg smells a little like raw meat.
5.  When tap the egg lightly, real egg makes a more crispy sound than the fake egg.
6.  When frying a fake egg, the yolk will spread without being touched.
7.  Fake eggs are larger than real eggs.

Experts warn residents of the danger of eating fake eggs. Not only they do not contain any nutrients, a long term consumption of alum could cause dementia. This is a very serious manner. Thus, we need to beware of these fake eggs.

Rusting: Oh my god, my nail become brown colour.

Rusting occur everywhere in our daily life. Only metals will rust.For example,iron nail,car and iron gate. The products is Fe₂O₃ . x H2O  which is brown colour.This oxidation process known as corrosion of the metals.

Rusting will occur that must have these all of the two conditions which are oxygen and water. The process of rusting needs an anode and cathode in different places on the surface of an iron piece. Oxidation half-reaction occur in anode.

Anode: 2Fe (s) → Fe²⁺ (aq)    + 4e^-

The four electrons from anode move to cathode. Reduction take place in cathode .Oxygen dissolved in water is reduced to become water in cathode.

Cathode: O₂ (g) + 4H⁺ (aq) + 4e^-→2H₂O (l)

When combine half-equation in anode and cathode,overall oxidation-reduction is:

2Fe (s) + O₂ (g) + 4H⁺ (aq) → 2Fe²⁺ (aq) +   2H₂O (l)

Fe²⁺ ions move out of the cathode then,it oxidizes to Fe³⁺ and contact with dissolved oxygen to form rust.

4 Fe²⁺ (aq)    + O₂ (g) + 4H₂O (l) → 2Fe₂O₃ . x H2O(s) + 8H⁺ (aq)

Rusting will occur faster when there are acid and salt presences. 3 ways can reduce rusting which is

using protective coating, alloying and sacrificial protection. Protective coating is to prevent air and

water reaching in the surface of iron. We can use oil and grease for moving part of engine. Paint also

can use for the objects which are not easily to scratch such as gates and car. Then, plastic can use for

light item such as clothes hanger and wire fences. Besides that, alloying iron to stainless steel also

prevent rusting. Stainless steel is composed of chromium, carbon, iron and nickel. The chromium and

nickel provide a protective oxide coating so firming bonded to iron and no easily to remove. Other

way is sacrificial protection that is using more electropositive metal as sacrificial metal attached to

iron. This can explain by the more electropositive metal will act as anode which is oxidation occur site

protect less electropositive metal rusting. For example, iron attach to magnesium. Magnesium more

electropositive than iron because magnesium more tendency to lose electron.