My Science School

In 1796, an English doctor called Edward Jenner (1749-1823) gave the first vaccination. He realized that milkmaids who caught cowpox did not catch the very dangerous disease of smallpox. By injecting the cowpox virus into a child, he was able to vaccinate him against the more serious disease. As the body fights the virus, antibodies are formed in the blood that prevents further infections or infection by some similar viruses. Today, huge vaccination programmers ensure that most children are protected against a range of diseases.

A person may become immune to a specific disease in several ways. For some illnesses, such as measles and chickenpox, having the disease usually leads to lifelong immunity to it. Vaccination is another way to become immune to a disease. Both ways of gaining immunity, either from having an illness or from vaccination, are examples of active immunity. Active immunity results when a person’s immune system works to produce antibodies and activate other immune cells to certain pathogens. If the person encounters that pathogen again, long-lasting immune cells specific to it will already be primed to fight it.

A different type of immunity, called passive immunity, results when a person is given someone else’s antibodies. When these antibodies are introduced into the person’s body, the “loaned” antibodies help prevent or fight certain infectious diseases. The protection offered by passive immunization is short-lived, usually lasting only a few weeks or months. But it helps protect right away.

Infants benefit from passive immunity acquired when their mothers’ antibodies and pathogen-fighting white cells cross the placenta to reach the developing children, especially in the third trimester. A substance called colostrum, which an infant receives during nursing sessions in the first days after birth and before the mother begins producing “true” breast milk, is rich in antibodies and provides protection for the infant. Breast milk, though not as rich in protective components as colostrum, also contains antibodies that pass to the nursing infant. This protection provided by the mother, however, is short-lived. During the first few months of life, maternal antibody levels in the infant fall, and protection fades by about six months of age.

Passive immunity can be induced artificially when antibodies are given as a medication to a nonimmune individual. These antibodies may come from the pooled and purified blood products of immune people or from non-human immune animals, such as horses. In fact, the earliest antibody-containing preparations used against infectious diseases came from horses, sheep, and rabbits.

Research chemists examine different chemicals to find out how they react with other chemicals and with living cells. When a mixture of chemicals is thought to have potential in the treatment of certain conditions, various combinations of the chemicals will be tested to see whether they might be dangerous to living things. Tests on individual cells and on animals are made before human beings are given the new drug. Many people think that drug-testing on animals is wrong, but others feel that this is the best way to make sure that drugs are safe. Trials of the drug, in which some patients are given a placebo (a drug with no active ingredients), carried out to assess the drug’s effectiveness. It is usually only after many years of testing and monitoring that the drug is released for use by doctors.

The journey will have begun in a university laboratory where researchers, with grants from the research bodies or the pharmaceutical industry, have undertaken basic research to understand the processes behind a disease, often at a cellular or molecular level. It is through better understanding of disease processes and pathways that targets for new treatments are identified. This might be a gene or protein instrumental to the disease process that a new treatment could interfere with, for example, by blocking an essential receptor.

Once a potential target has been identified, researchers will then search for a molecule or compound that acts on this target. Historically, researchers have looked to natural compounds from plants, fungi or marine animals to provide the basis for these candidate drugs but, increasingly, scientists are using knowledge gained from the study of genetics and proteins to create new molecules using computers. As many as 10,000 compounds may be considered and whittled down to just 10 to 20 that could theoretically interfere with the disease process.

The next stage is to confirm that these molecules have an effect and that they are safe. Before any molecules are given to humans, safety and efficacy tests are conducted using computerised models, cells and animals. Around half of candidates make it through this pre-clinical testing stage and these five to 10 remaining compounds are now ready to be tested in humans for the first time. In the UK, approval by the Medicines and Healthcare products Regulatory Agency (MHRA) is required before any testing in humans can occur. The company will put in a clinical trial application (CTA), which will be reviewed by medical and scientific experts, who will decide whether or not sufficient preliminary research has been conducted to allow testing in humans to go ahead.

Each year sees a couple of dozen new drugs licensed for use, but in their wake there will be tens of thousands of candidate drugs that fell by the wayside. The research and development journey of those new drugs that make it to market will have taken around 12 years and cost around £1.15bn.

Understanding the cause of an illness can often help a doctor to bring a patient back to good health or to suggest ways to prevent the illness from recurring or affecting other people. Illness may he caused by an accident, which physically affects part of the body, or it may be brought about by tiny organisms such as bacteria and viruses. Antibiotics are used to treat bacterial infections, while antiviral drugs attack viruses. In both cases, some disease-causing organisms are resistant to drug therapy. Occasionally, the cells of the body seem to act in destructive ways for no obvious reason. This is what happens in some forms of cancer. However, researchers are finding new ways to combat disease all the time.

A complex illness contains two or more elements of illness, causal illness, injury illness and blockage illness, with a single cause. A complex illness requires a cure for each illness element.

For complex illnesses, the first cure is to address the cause.  The second cure is to heal the damage, the third to transform the negative attributes that resulted from illness and from healing. It is possible, sometimes necessary to work on elemental cures out of sequence, or at the same time. However, cures can seldom be completed out of sequence, because the prior illness is a cause, and the illness will recur.

The hierarchy is also a hierarchy of life and of health. It is also useful to view the hierarchy of illness. An illness can exist in a single cell, the simplest life form. A single cell might have an illness with a single cause that causes an injury that is healed, but leaves a blockage resulting in congestion.

An illness might exist in a bodily tissue, independent of the cells comprising the tissue.  A tissue is a layer of life above individual cells.  A tissue might have an illness because that is not a cause of cellular illnesses that leads to tissue injury, which heals and leaves a tissue blockage, resulting in congestion in the tissue.  In the same manner, a limb, or an organ, or an organ system might have a simple or compound illness.

An illness can be based in an organ, an organ system, or in the body.  This is the common view of much of today’s medical practice. It is sometimes a useful view, sometimes not so useful. The illness of the body, like that of a cell, or that of a tissue might begin with a cause, or as an injury or a blockage, caused by an internal or external factor.

An illness might also arise in the mind, or the spirit, or even the community aspects of a life entity, from internal or external causes. An illness might result in damage to the mind, or to the spirit, or to the community aspects of the patient, which when healing is not perfect, results in a negative attribute – leading to congestion, and possibly even a new illness.

Anaesthesia prevents pain signals from being received by the brain, so that the pain is not felt by the patient. Hundreds of years ago there were few ways to relieve a patient’s pain during surgery. Alcohol might be used, but it was not very effective. It was not until the nineteenth century that anaesthetic drugs began to be widely used. The first operation to be performed using a general anaesthetic was by an American surgeon, in 1842.

Anaesthesia refers to the practice of blocking the feeling of pain to allow medical and surgical procedures to be undertaken without pain.

 An ancient Italian practice was to cover a patient’s head with a wooden bowl and beat on it repeatedly until the patient lost consciousness. Presumably this method resulted in a number of side-effects the patient would not have found beneficial.

Opium and alcohol were regularly used to produce insensibility, both of which also had a number of negative side effects and neither could dull the pain completely. Few operations were possible and speed was the determinant of a successful surgeon. Patients were often tied or held down and the abdomen, chest and skull were effectively inoperable. Surgery was a last, and extremely painful, resort.

On October 16, 1846, an American dentist, William Morton, proved to the world that ether causes complete insensibility to pain during an operation performed in front of a crowd of doctors and students at the Massachusetts General Hospital. Morton instructed the patient to inhale the ether vapour and, once the patient was suitably sedated, a tumour was removed from his neck. The patient felt no pain. This demonstration transformed medical practice.

Archaeologists have found skulls, dating from at least 10,000 years ago, that have holes drilled into them. Because bone has begun to grow around the holes, they were clearly made while the person was still alive. It is believed that this technique, called trepanning, was the first operation. It was probably done to relieve headaches or to let out evil spirits that were thought to be trapped inside the patient’s head.

The history of dental and surgical procedures reaches back to the Neolithic and pre-Classical ages. The first evidence of a surgical procedure is that of trephining, or cutting a small hole in the head. This procedure was practiced as early as 3000 BC and continued through the middle Ages and even into the Renaissance.  The initial purpose of trephining in ancient cultures is unknown; although some hypothesize it may have been used to rid the body of spirits. The practice was widespread throughout Europe, Africa, and South America. Evidence of healed skulls suggests some patients survived the procedure. Trephining continued in Ancient Egypt as a method of treating migraines. In South America, ancient Mayans practiced dental surgery by filling cavities with precious stones including jadeite, turquoise, quartz, and hematite, among others. It is supposed that these procedures were for ritual or religious purposes, rather than health or cosmetic reasons.

Ancient Greeks also performed some surgical procedures including setting broken bones, bloodletting, draining lungs of patients with pneumonia, and amputations. The Greeks had new, iron tools at their disposal, yet the risk of infection or death was still high. Hippocrates’ theory of four humors influenced medicine for hundreds of years. He claimed that the humors (black bile, yellow bile, phlegm, and blood which coincided with the elements earth, fire, water, and air, respectively) exist in the body, and bloodletting (or the draining of blood), among other procedures, balanced them. Ancient Roman physician Galen was heavily influenced by the Greeks. He served for three years as doctor to Roman gladiators and as the Emperor’s surgeon, gaining hands-on surgical experience. Romans continued with trephining, amputations, and eye surgery. Beginning in 900 AD, Al-Zahrawi, a famous Islamic surgeon, wrote books focused on orthopedics, military surgery, and ear, nose, and throat surgery, further influencing Islamic and Western medical practitioners.

Hippocrates is often described as “the father of modern medicine”. He was a Greek doctor, living in the fourth and fifth centuries BC , who taught that a doctor’s first duty is to his or her patient and that the aim must at all times be to try to do good rather than harm. When they qualify, many modern doctors take the Hippocratic Oath, promising to follow these principles throughout their careers.

Hippocrates was born around 460 BC on the island of Kos, Greece. He became known as the founder of medicine and was regarded as the greatest physician of his time.

He based his medical practice on observations and on the study of the human body. He held the belief that illness had a physical and a rational explanation. He rejected the views of his time that considered illness to be caused by superstitions and by possession of evil spirits and disfavor of the gods.

Hippocrates teaching Hippocrates held the belief that the body must be treated as a whole and not just a series of parts. He accurately described disease symptoms and was the first physician to accurately describe the symptoms of pneumonia, as well as epilepsy in children. He believed in the natural healing process of rest, a good diet, fresh air and cleanliness. He noted that there were individual differences in the severity of disease symptoms and that some individuals were better able to cope with their disease and illness than others. He was also the first physician that held the belief that thoughts, ideas, and feelings come from the brain and not the heart as others of his time believed.

Hippocrates traveled throughout Greece practicing his medicine. He founded a medical school on the island of Kos, Greece and began teaching his ideas. He soon developed an Oath of Medical Ethics for physicians to follow. This Oath is taken by physicians today as they begin their medical practice. He died in 377 BC. Today Hippocrates is known as the “Father of Medicine”.

Plastic materials can be shaped very efficiently by machines, so plastic objects are cheaply made in great numbers. Some people think that this has contributed to the “disposable society”, where we are inclined to throw something away when it is worn or broken, instead of trying to mend it, as would have happened in the past. They warn, too, that most plastics do not easily decay, so our thrown-away food cartons and shopping bags will remain to pollute the planet for years to come. However, plastics have also brought great benefits, playing a part in so many aspects of our lives that it is difficult now to imagine the world without them.

There has been no material more revolutionary than modern plastic. Used in almost every single industry in a vast range of ways thanks to its versatility, high durability and ability to be molded into whatever shape necessary, no material has changed (and in many ways, shaped) the world like plastic has.

Since then, plastic took over the world. Thanks to its ability to remain sterile while acting as a container, plastic was used in the formation of bottles for items such as milk, which no longer had to be delivered in glass bottles. In the food industry, plastic has had an amazing, incalculable effect. Raw meat can be kept in plastic packaging to prevent potential diseases, while the use of plastic trays to keep food fresh has helped to diminish waste in stores.

Plastic has had a profound impact on almost every industry it has touched. Medicine benefited greatly from the development of the disposable plastic syringe in 1955, for instance. In fact, if we were to swap plastic for any other material to be used in the same way, it would exponentially increase greenhouse gases being emitted. The effect plastic has had on the nascent industrial world cannot be denied.

Basically, plastics are lightweight, inexpensive and high in quality. Before, buckles are made of metal and are heavier compared to the quick release buckles we use today. Weight really matters a lot in any industry because of storage and shipping issues. It is far easier and lighter to ship plastic buckles than metal buckles, making it more ideal for manufacturers, suppliers, and dealers alike.

Although plastics are considered cheaper, we cannot deny the quality it can offer. Aside from the fact that it is easier to store and ship, manufacturing plastics allow for more flexibility and creativity of the part of plastic manufacturers. Since it is highly malleable, plastics are very easy to customize so practically, any design brought to mind can be manufactured in no time at all!

Take for example plastic spoons and forks. If you will account the cost of damaged or lost utensils, values are probably going to stack up but if you will be using the plastic type, it would the most economical option. Aside from that, you don’t have to wash it with soap and water again and again because it is disposable. Same economics may be applied to quick release buckles too.

Another reason why plastics are preferred over metal is due to is hygienic qualities. It helps prevent the spread of diseases due to improperly cleaned metal cutlery. Now that you know the advantages of using plastics, can you imagine a day in your life without using it more than once? Is it even possible to run your day without it?

Starch, rubber, wool, silk and hair are all natural polymers. Their molecular structure, under the right conditions, makes them strong and flexible.

A polymer is basically synthesized by joining small molecules or substances into a single giant molecule by a chemical process. The small molecules which are used in synthesizing a polymer are called as monomer. Natural Polymers are those substances which are obtained naturally. These polymers are formed either by the process of addition polymerization or condensation polymerization.

Polymers are extensively found in nature. Our body too is made up of many natural polymers like nucleic acids, proteins, etc. The Cellulose is another natural polymer which is a main structural component of the plants. Most of the natural polymers are formed from the condensation polymers and this formation from the monomers, water is obtained as a by-product.

Latex is known to be a kind of rubber, and rubber is a natural polymer. This latex occurs in both the forms either synthetic or natural. The natural form of latex is mainly collected from the rubber trees and it is also found in variety of plants which includes the milkweed. It can also be prepared artificially by the process of building up long chains of molecules of styrene.

Natural rubber, also called by other names of India rubber, latex, Amazonian rubber, caucho, as initially produced, consists of polymers of the organic isoprene, with minor impurities of other organic compounds, plus water. Thailand and Indonesia are two of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers.

Currently, rubber is harvested mainly in the form of the latex from the rubber tree or others. The latex is a sticky, milky colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called “tapping”. The latex then is refined into rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for marketing.

Some plastics, such as polythene, can be melted and reshaped over and over again. These plastics are recyclable and are called thermoplastics. Other plastics are more resistant to heat and cannot be melted and reshaped. They are known as thermoset. Plastic kitchen work-surfaces and the hard plastic casings around some electrical goods are made from thermoset.

Though thermoset plastics and thermoplastics sound similar, they have very different properties and applications. Understanding the performance differences can help you make better sourcing decisions and improve your product designs.

The primary physical difference is that thermoplastics can be remelted back into a liquid, whereas thermoset plastics always remain in a permanent solid state. Think of thermoplastics as butter – butter can be melted and cooled multiple times to form various shapes. Thermoset is similar to bread in that once the final state is achieved, any additional heat would lead to charring.

Thermoset

Thermoset plastics contain polymers that cross-link together during the curing process to form an irreversible chemical bond. The cross-linking process eliminates the risk of the product remelting when heat is applied, making thermosets ideal for high-heat applications such as electronics and appliances.

Thermoset plastics significantly improve the material’s mechanical properties, providing enhances chemical resistance, heat resistance and structural integrity. Thermoset plastics are often used for sealed products due to their resistance to deformation.

Thermoplastics

Thermoplastics pellets soften when heated and become more fluid as additional heat is applied. The curing process is completely reversible as no chemical bonding takes place. This characteristic allows thermoplastics to be remolded and recycled without negatively affecting the material’s physical properties.

There are multiple thermoplastic resins that offer various performance benefits, but most materials commonly offer high strength, shrink-resistance and easy bendability. Depending on the resin, thermoplastics can serve low-stress applications such as plastic bags or high-stress mechanical parts.

Plastic may be shaped in various ways. It can be extruded (pushed through a nozzle when liquid) to form sheets, tubes and fibers. Molten plastic can be poured into moulds. Vacuum forming is a way of making complicated plastic shapes. A sheet of warm plastic is placed over a mould, and then the air is sucked from under it so that the sheet is pulled firmly against the sides of the mould. When the plastic is cooled, it retains the mould’s shape. Disposable cups are often made in this way.

Metalworking using machines and machine tools includes cutting using a lathe, plastic forming, and welding. When grouped with other such metalworking techniques, plastic forming is also called stamping and makes the designed shapes by pressing the material into a die. This processing method utilizes the plasticity—the characteristic that a material remains in the shape it is changed to by the application of a certain force—of metals and other solids. Plastic forming is primarily used in the metalworking of steel materials such as those for automobile parts. Unlike cutting with a lathe, this method does not produce chips and also allows mass production of the same parts through mold pressing.

There are two types of plastic forming: Cold-plastic forming, which is performed at ambient temperatures, and hot-plastic forming, which uses heat. When heated, metal undergoes thermal expansion and changes shape. As such, cold-plastic forming is used whenever possible and hot-plastic forming is used only when the material of the target being produced is hard.

Some examples of other types of plastic forming include forging for manufacturing nuts and bolts; extrusion, wire drawing, and pultrusion for forming wire materials and pipes; deep drawing for creating spherical surfaces in metal sheets; bending for producing leaf springs; riveting for securing assemblies in place; and shearing for cutting metal sheets.

Almost anything can be made from plastic! Plastic packaging keeps food fresh and protects it from bacteria. A plastic coating, called Teflon, can prevent food from sticking to cooking pans. Plastic can be elastic, like the skin of a balloon, or very rigid and reinforced with other fibers, as in a protective helmet. Plastic can also be a good insulator. A plastic sleeve on electrical wiring protects the wires from corrosion and the user from electric shocks. Polystyrene packaging can help to keep take-away food warm. Plastic can be dyed in bright colours or completely transparent, to make spectacles and contact lenses. Without plastics, there would be less music in our lives, with no cassette tapes, compact discs or even old-fashioned records.

Plastic, polymeric material that has the capability of being molded or shaped, usually by the application of heat and pressure. This property of plasticity, often found in combination with other special properties such as low density, low electrical conductivity, transparency, and toughness, allows plastics to be made into a great variety of products. These include tough and lightweight beverage bottles made of polyethylene terephthalate (PET), flexible garden hoses made of polyvinyl chloride (PVC), insulating food containers made of foamed polystyrene, and shatterproof windows made of polymethyl methacrylate.

Many of the chemical names of the polymers employed as plastics have become familiar to consumers, although some are better known by their abbreviations or trade names. Thus, polyethylene terephthalate and polyvinyl chloride are commonly referred to as PET and PVC, while foamed polystyrene and polymethyl methacrylate are known by their trademarked names, Styrofoam and Plexiglas (or Perspex).

Industrial fabricators of plastic products tend to think of plastics as either “commodity” resins or “specialty” resins. (The term resin dates from the early years of the plastics industry; it originally referred to naturally occurring amorphous solids such as shellac and rosin.) Commodity resins are plastics that are produced at high volume and low cost for the most common disposable items and durable goods. They are represented chiefly by polyethylene, polypropylene, polyvinyl chloride, and polystyrene. Specialty resins are plastics whose properties are tailored to specific applications and that are produced at low volume and higher cost. Among this group are the so-called engineering plastics, or engineering resins, which are plastics that can compete with die-cast metals in plumbing, hardware, and automotive applications. Important engineering plastics, less familiar to consumers than the commodity plastics listed above, are polyacetal, polyamide (particularly those known by the trade name nylon), polytetrafiuoroethylene (trademark Teflon), polycarbonate, polyphenylene sulfide, epoxy, and polyetheretherketone. Another member of the specialty resins is thermoplastic elastomers, polymers that have the elastic properties of rubber yet can be molded repeatedly upon heating.

Plastics are polymers, which means that they are made of lots of small molecules joined together to form larger molecules in the form of long chains. Polymers can be manufactured from crude oil, natural gas, or coal. They include artificial fibers and many kinds of plastic. Plastics are extremely useful because they are extraordinarily versatile. They are easy to shape and color. They can be made into rigid objects or thin, pliable sheets. Some plastics are heatproof, while others melt at low temperatures.

Plastic is a material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and therefore can be molded into solid objects. Plasticity is the general property of all materials that involves permanent deformation without breaking. Polymers’ name is derived from their flexible and plastic properties.

Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic and most commonly derived from petrochemicals. However, today’s focus on the environment has led to a growing number of plastics to be derived from renewable materials such as polylactic acid from corn or cellulosic’s from cotton linters.

Plastics have been adopted in a significant, and ever-expanding, range of products thanks to their relatively low cost, ease of manufacture, versatility, and imperviousness to water. They can be found in products as simple as paperclips or as complex as planes.

A large source of diverse plastic material is available across a widespread manufacturing spectrum. One of the most recent and exciting manufacturing domains is in 3D Printing. As new applications for 3D Printing are discovered almost daily, diverse arrays of plastic objects have already been produced using the 3D Printing process. These objects can be found in prototyping labs, toys, mechanical gearboxes, medical prosthetics, and many more. Plastics are generally classified by the chemical structure of the polymer's backbone and side chains.