ASPIRIN

The Chemistry of AspirinAspirin, one of the first drugs to come into common usage, is still mostly the widely used in the world - approximately 35,000 metric tonnes are produced and consumed annually, enough to make over 100 billion standard aspirin tablets every year.
Aspirin, also known as 'acetylsalicylic acid', has a chemical formula of C9H8O4.

The chemical structure of aspirin:

Aspirin, is analgesic, anti-inflammatory, antipyretic and is an inhibitor of platelet aggregation. It inhibits fatty acid cyclo-oxygenase by acetylation of the active site of enzyme and the pharmacological effects of aspirin are due to the inhibition of the formation of cyclo-oxygenase products including prostglandins, thromboxanes and prostacyclin.
Aspirin is prepared by chemical synthesis from salicylic acid, by acetylation with acetic anhydride.

Reactions

Raw Materials

Phenol C6H5-OH

Sodium Hydroxide NaOH

Carbon Dioxide CO2

Acetic Anhydride CH3COOCOCH3

Hydrogen H

The Reactions

The production of aspirin from raw materials can be divided into four separate reactions. These are shown below:

Testing the Effectiveness of Sunscreens

Purpose

Determine the effectiveness of suntan lotions in screening out UV radiation using the benzopinacol reaction.

Introduction:

The sun produces all forms of electromagnetic energy. Some of this energy is visible light while most falls outside the range of wavelengths that are visible to the human eye. For example, the sun produces infrared, radio and ultraviolet radiation that our eyes cannot detect. Ultraviolet radiation makes up a small fraction of sunlight but it a much more energetic radiation than visible light.
Ultraviolet (UV) radiation is often divided into three different ranges; UV-A, UV-B, and UV-C. UV-A radiation constitutes about 90-95% of the UV radiation that reaches the Earth’s surface. It has the longest wavelengths (315-400 nm) and the lowest energy in inducer of tanning in humans. UV-A can also damage the skin the furthest and is the primary inducer of tanning humans. UV-A can also damage eyes and lead to an increase in cataracts. UV-B rays have a medium wavelength (290-315 nm) and are partially absorbed by the ozone layer. UV-B radiation does not penetrate the skin as far as UV-A rays do but they contain much more energy. UV-B is responsible for activating the synthesis of vitamin D. UV-B radiation is the primary cause of sunburn and can cause cellular damage to the skin and eyes. UV-C radiation is the highest energy ultraviolet wavelength (200-290 nm) but most of it is absorbed by the ozone layer in the Earth’s upper atmosphere. Recent satellite readings show that the ozone layer has been damaged and is thinning. This may allow more UV light to reach the Earth’s surface UV radiation is seen as a threat to animals and plants since UV radiation can cause changes in the chemical bonds of sensitive compounds.
When your skin absorbs UV radiation, two effects occur. First, melanin (substance located in protective cells) absorbs as much UV radiation as possible and is oxidized to a darker color, giving a tan in a few hours. The second effect is the destruction of the keratinocyte cells (responsible for producing new cells), or even worse, a rearrangement or chemical change in the DNA within the keratinocyte cells. If the keratinocyte cells are destroyed, the nervous system sensors are also damaged resulting in pain and increase in the blood circulation in the area and producing the characteristic red skin of sunburn. If the DNA is damaged, mutations may occur resulting in age spots, wrinkling, and cancer. The higher the level of UV exposure, the more likely the keratinocyte cells will be damaged.
To limit the amount of exposure to harmful UV radiation, sunscreens are recommended. Suntan and sunblock lotions are two different products. Sun blocks contain compounds like titanium dioxide or zinc oxide that completely prevent all light from reaching the skin. Suntan lotions contain compounds that absorb UV radiation and reduce the amount of UV radiation that is absorbed by the skin. The ability of a sunscreen to protect the user from UV radiation is defined as the Sun protection factor (SPF).　
The SPF is the ratio of the amount of UV radiation required to produce pinkness in skin covered by the sunscreen (assessed 24 hours after exposure) to the amount of UV radiation required to produce a similar level of pinkness in unprotected skin. If a sunscreen reduces the effect of sunlight on skin by 50%, it would have a SPF of 2; if by 75%, the SPF would be 4. A sunscreen with a SPF of 30 reduces the UV radiation exposure by 96.7%.
Less UV penetration protects skin cells from the damaging effects of UV light. While the lotion limits damage to a cell’s DNA, it also prevents the UV from reacting melanin-containing cells and therefore prevents tanning. The more protection given by the suntan lotion, the higher its SPF.
Suntan lotions contain compounds that effectively absorb UV radiation. The compounds absorb most of the UV radiation, thus decreasing possible skin and cellular damage. Suntan lotions are normally clear and contain aromatic organic compounds. Benzene rings in aromatic compounds are very effective at absorbing UV radiation. Some common molecules used as active ingredients in suntan lotions are shown in Figure 1.

In this experiment, the effectiveness of suntan lotions will be analyzed using the reaction to produce benzopinacol. Benzophenone (two phenyl groups attached to a ketone) absorbs ultraviolet light to produce an excited state. This excited molecule abstracts a proton from the solvent (isopropyl alcohol) to form a radical that then dimerizes to benzopinacol (Figure 2).

In benzophenone, the most loosely held electrons are the two pairs of nonbonded electrons on the carbonyl oxygen. These electrons have the highest energy are therefore the most easily excited. One of these electrons is excited by the UV light into the lowest unoccupied excited state, which is the carbon from the carbonyl group. The activated state abstracts a proton from the isopropyl alcohol solvent to form a diphenyl hydroxyl radical. The isopropyl alcohol radical loses another proton to form acetone. Two diphenyl hydroxyl radicals will dimerize to produce benzopinacol.
The reaction proceeds nearly 100% completion and the produce is insoluble in isopropyl alcohol. Yields of > 90% are possible. The more UV light that reaches the solution of benzophenone and isopropyl alcohol, the greater the amount of benzopinacol precipitate formed. Therefore, the difference in yield between a vial coated with suntan lotion and one without will be proportional to the reduction in absorbed UV radiation caused by the suntan lotion.

Hydrogen Fuel

General Fuel Cell Characteristics

Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly to usable energy - electricity and heat - without combustion. This is quite different from most electric generating devices (e.g., steam turbines, gas turbines, reciprocating engines), which first convert the chemical energy of a fuel to thermal energy, then to mechanical energy and finally to electricity. Fuel cells are similar to batteries containing electrodes and electrolytic materials to accomplish the electrochemical production of electricity.
Batteries store chemical energy in an electrolyte and convert it to electricity on demand, until the chemical energy has been depleted. Applying an external power source can recharge depleted secondary batteries, but primary batteries must be replaced. Fuel cells do not store chemical energy, but rather, convert the chemical energy of a fuel to electricity. Thus fuel cells do not need recharging and can continuously produce electricity as long as fuel and oxidant are supplied. Figure 1 presents the basic components of a fuel cell, which include a positive electrode (anode), negative electrode (cathode) and an electrolyte. Fuel is supplied to the anode (positive electrode) while oxidant is supplied to the cathode (negative electrode). Fuel is electrochemically oxidized on the anode surface and oxidant is electrochemically reduced on the cathode surface. Ions created by the electrochemical reactions flow between anode and cathode through the electrolyte. Electrons produced at the anode flow through an external load to the cathode completing an electric circuit.

A typical fuel cell requires gaseous fuel and oxidant flows. Hydrogenis the preferred fuel because of its high reactivity, which minimizes the need for expensive catalysts, and because electro-oxidation of hydrogen leads only to water emission. Hydrocarbon fuels can be supplied but typically require conversion to hydrogen or a hydrogen-rich mixture before electrochemical reaction can occur. This fuel processing step can be accomplished prior to entering the fuel cell (for lower temperature fuel cells) or within the fuel cell (for higher temperature fuel cells). Oxygen in air is the preferred oxidant because of its availability in the atmosphere.As indicated in Figure 1, the electrolyte serves as an ion conductor.The direction of ion transport depends upon the fuel cell type, which determines the type of ion that is produced and transported across the electrolyte between the electrodes. The various fuel cell types are described in a subsequent section.A single fuel cell is only capable of producing about 1 volt, so typical fuel cell designs link together many individual cells to form a “stack” that produces a more useful voltage. A fuel cell stack can be configured with many groups of cells in series and parallel connections to further tailor the voltage, current and power produced. The number of individual cells contained within one stack is typically greater than 50 and varies significantly with stack design. Figure 2 presents the basic components that comprise the fuel cell stack. These components include the electrodes and electrolyte of Figure 1 with additional components required for electrical connections and to provide for the flow of fuel and oxidant to each cell in the stack. These key components include current collectors, separators, and gas flow channels, which are often integrated into one design as in the “interconnect” design pictured in Figure 2. This interconnect serves as current collector and gas separator and provides the flow channels for both fuel and oxidant. The interconnect provides the electrical connections between cells and physically separates the oxidant flow of one cell from the fuel flow of the adjacent cell. The channels serve as the distribution pathways for the fuel and oxidant. The preferred fuel for most fuel cell types is hydrogen. Hydrogen is not readily available, but, and the infrastructure for provision of hydrocarbon fuels is well established in our society. Thus, fuel cell systems that have been developed for practical power generation applications to-date have been designed to operate on hydrocarbon fuels. This typically requires the use of a fuel processing system or “reformer” as shown in Figure 3. The fuel processor typically accomplishes the conversion of hydrocarbon fuels to a mixture of hydrogen rich gases and, depending upon the requirements of the fuel cell, subsequent removal of contaminants or other species to provide pure hydrogen to the fuel cell.
In addition to the fuel cell system requirement of a fuel processor for operation on hydrocarbon fuels, Figure 3 presents the need for a power conditioning or inverter system component as well. This is required for the use of current end-use technologies that are designed for consuming alternating current (AC) electricity, and for grid connectivity in distributed power applications. Since the fuel cell produces direct current (DC) electricity, the power conditioning section is a requirement for fuel cell systems that are designed for distributed generation today. In the future, systems and technologies may be amenable to the use of DC electricity, which would allowsignificant cost savings.

Cement

What is cement and how is it made?
Cement is a fine, soft, powdery-type substance. It is made from a mixture of elements that are found in natural materials such as limestone, clay, sand and/or shale. When cement is mixed with water, it can bind sand and gravel into a hard, solid mass called concrete.

An example of how cement can be made

1.) Limestone is taken from a quarry. It is the major ingredient needed for making cement. Smaller quantities of sand and clay are also needed. Limestone, sand and clay contain the four essential elements required to make cement. The four essential elements are calcium, silicon, aluminum and iron.

2.) Boulder-size limestone rocks are transported from the quarry to the cement plant and fed into a crusher which crushes the boulders into marble-size pieces.

3.) The limestone pieces then go through a blender where they are added to the other raw materials in the right proportion.

4.) The raw materials are ground to a powder. This is sometimes done with rollers that crush the materials against a rotating platform.

5.) Everything then goes into a huge, extremely hot, rotating furnace to undergo a process called "sintering". Sintering means: to cause to become a coherent mass by heating without melting. In other words, the raw materials become sort of partially molten. The raw materials reach about 2700° F (1480°C) inside the furnace. This causes chemical and physical changes to the raw materials and they come out of the furnace as large, glassy, red-hot cinders called "clinker".

6.) The clinker is cooled and ground into a fine gray powder. A small amount of gypsum is also added during the final grinding. It is now the finished product - Portland cement. The cement is then stored in silos (large holding tanks) where it awaits distribution. The cement is usually shipped in bulk in purpose-made trucks, by rail or even by barge or ship. Some is bagged for those who want small quantities

Comparing Reactions1

Hydration Reactions

Hydration reactions are semi stoichoimetric2 – for example two moles of di calcium silicate
(a monomer) take on water releasing calcium (which then combines with hydroxides from
water) to form a mole of di calcium silicate hydrate (a dimer)3
2Ca2SiO4 + 5H2O ==> Ca3Si2.O7.4H2O + Ca(OH)2
Using “atom and stick” nomenclature

The pozzolanic reaction is similar to the hydration reaction for di and tri calcium silicate;
the difference is that the components all come together to form compounds that are
hydrated silicates with less calcium and bound water.
1.1Ca(OH)2 + SiO2 + .67H2O ==> Ca1.1SiO3.1.2.1H2O
Atoms don’t come in fractions so the formula suggest that larger molecules are formed that
are probably oligopolymers – and with the pozzolanic reaction they are.

Silicification Reactions

Hydrolysis and Recombination

As portlandite is formed in reactions like the one depicted above the pH of the mix rises to
around 12.5 at equilibrium4.
At high pH the surfaces of silica and alumina containing compounds tend to hydrolyze.
Strength giving reactions occur when the hydrolyzed surfaces then bind back together
losing water as depicted in the “atom and stick” diagram below.

In tec-cement concrete formulations many wastes containing silica and alumina such as fly
ash and ground granulated blast furnace slag5 can be added in high proportion and tend to
recombine in the above manner as well as becoming involved in the pozzolanic reaction.

Comparing Bonds with Aggregates

In PC concretes there is no chemical bond with aggregates – they are physically held in
place. Portlandite also tends to form around larger aggregates weakening the bond to
them. A further source of weakness is the reaction between alkali and silica
Geopolymers are different in that the geopolymeric paste tends to bond with silica in the
micro aggregates and aggregates and this together with cross linking are reasons for high
strength, .

Botox

Botox treatment is the most common aesthetic procedure in the world. Its popularity results from its effectiveness in restoring a youthful appearance without any downtime. This article gives you facts and details about Botox to remove the mystery and myths about this treatment.

What is Botox?

Botox is a brand name for botulinum toxin, a highly purified protein which is injected in very small doses to reduce or eliminate wrinkles. The other brand available in Singapore known as “Dysport” works in exactly the same way. For the purposes of this article, we will call botulinum toxin as “Botox” but the treatment and effects are the same with “Dysport”. The US FDA, which is the organization in the US that approves the use of medications in the US based on scientific evidence and safety profile, has approved Botox for use in certain medical conditions since the 1980s. Its effectiveness for reducing wrinkles was discovered more recently, where patients receiving Botox for lazy eye were also found to have fewer wrinkles. Since then, doctors have been using Botulinum toxin for cosmetic purposes.

How does it work?

Botox temporarily blocks the signal from a nerve to a muscle. The treated muscles are weaker, so that the wrinkle formed by muscle contraction relaxes and softens. Because of its mechanism of action, Botox works best for lines that are formed because of muscle contraction such as frown lines and horizontal forehead lines, as well as crow's feet.
Botox treatment lasts three to six months. Lines and wrinkles gradually reappear as Botox wears off. With repeated treatments, doctors have observed that Botox may last longer as the muscles become less prominent from non-use. Wrinkles resulting from gravity or sun damage, as well as pigments or laxity are not treated by Botox. Other laser or light treatments may be used alone or in combination with Botox to address these other related concerns.

What are the clinical uses of Botox?

Botox is used to treat wrinkles that form because of repeated muscle contraction. These include muscles used for frowning, smiling, concentrating or thinking. These usually present as horizontal lines on the forehead, or grooves between the eyebrows, as well as smile lines (crow's feet) around the eyes. Botox is also used to lift the eyebrows (“brow lift”), make the eyes appear rounder, and to correct lines around the lips and necks. In Singapore and the rest of Asia, a common use for Botox is to “slim” the lower face when it is injected on the muscles we use for chewing (“masseter muscle”) along the angles of the jaw.
There are other non-cosmetic uses of Botox including reduction of excessive underarm or palm sweating (hyperhydrosis”), the treatment of headaches, and the management of spastic conditions.

How is the procedure performed?

A Botox treatment takes only a few minutes. You can come in to talk to the doctor, have the treatment, then go straight back to work without downtime. The treatment will weaken only the muscles that produce wrinkles so your natural facial expressions will not be affected.
Tiny amounts of Botox are injected into specific muscles and because a very fine needle involved,it is almost “pain-free”. Some patients may ask for a little numbing cream but most people describe the treatment as like a little “ant bite”.
If you're considering a Botox treatment, tell the doctor what medications you are on since some medications (for example aspirin) may increase the risk of bruising. The injection usually takes three to 7 days to take effect and the doctor may ask you to pop in after a week to assess the results. The doctor may also ask you to use the muscles that are injected so that the Botox takes effect in the right areas. You will also be asked to avoid lying down for a few hours.