Frozen smoke, the world’s lightest solid material, is hard at work powering supercapacitors, insulating space ships, firefighters, surfers and rockets, thickening paints and cosmetics, performing classified roles in nuclear weapons, collecting interstellar dust… It is one of the lightest, most expensive substances on Earth, and we are surrounded by it.
Aerogel, also known as frozen smoke, solid smoke or solid air, is an ultralight synthetic material produced from a gel. Composed of 99.98% air, it looks and feels like very light polystyrene, with a slight blueish tinge. First developed in the 1930s as the result of a bet, aerogels are incredibly light, strong and flexible, and are being applied to everything from home decor to aerospace engineering.
All the beautiful, remarkable complexities of life that we see around us are, believe it or not, encoded at the most basic level by an alphabet just 5 letters long. The DNA code, which is shared by all life on Earth, is formed from molecules known as nucleotides which come in just four forms: Adenine, Cytosine, Guanine and Thymine. RNA, the single-stranded cousin of DNA which is important in translating DNA into protein, adds a fifth letter – Uracil. It is truly one of the most impressive feats of evolution, that such a simple alphabet can generate such diversity and adaptation. However, recently scientists from The Scripps Research Institute, California have engineered a life form with an expanded vocabulary.
Believe it or not, out there somewhere, in a brightly lit laboratory, is a person in a lab coat, folding DNA, proteins and other biological compounds to provide innovative new medicines, tackle microengineering problems and create intriguing art. Welcome to the world of nantechnology.
The structure of DNA
Nanotechnology is the study of materials and devices smaller than 100 nanometers (10-5 or 0.000001 cm), and it is being applied to a diverse set of problems including drug delivery, nanorobotics, gene therapy, microelectronics and molecular computing. DNA nanotechnology involves the construction of self-assembling minute artificial structures from nucleic acids (the building blocks of DNA). DNA can be used to form a functional nanostructure itself, or it can be used as a scaffold to direct the assembly of other molecules (e.g. carbon, protein, peptides) into a functional structure. This is possible because of the strict base pairing rules of DNA, which means that strands will only bind together if they share complementary sequences. Base sequences can be therefore designed that will form specific structures. This is a major advantage over other materials used in nanotechnology such as proteins and nanoparticles. Dynamic DNA nanostructures can also be designed that react to certain chemical or physical stimuli, and DNA engineering is allowing scientists to design sequences that catalyse reactions, influence gene expression and modify the properties of natural DNA. Even more amazingly, DNA ‘printers’ have now been developed which can produce DNA strands with specific sequences, and bind them to a surface.
Around 125 million people wear contact lenses world wide, generally to correct vision. But soon even those of us with 20-20 vision might be wearing them, as scientists have made early successes in incorporating computers into contact lenses.
The Science of Artificial Hands
Our hands are possibly our most versatile tool; we use them for almost every aspect of our daily lives and few of us could imagine surviving without them. For those unlucky enough to suffer from congenital hand malformations, or amputees as a result of disease or injury, this is even more clear. In the US, over 40,000 people have undergone hand or arm amputation, most commonly due to injury, cancer or vascular complications of diseases such as diabetes. Although limb loss may once have been a truly debilitating and lifetime loss, remarkable advances in artificial limb technology are making the outlook for amputees much better.
Mind reading no longer exclusively belongs to the domain of science fiction writers and mediums. Over the last 50 years, researchers around the world have been working on a system known as the brain-computer interface (BCI) which allows direct communication between the brain and an external device such a computer or a robotic limb. The main goal of this research is to develop technology capable of restoring sensory function to the blind or deaf, and restoring movement to patients suffering from paralysis. Major strides have been made in this endeavour over the last decade, and BCI technology is now even being adapted to commercial purposes such as gaming.
BCI technology is possible because of the way in which the brain transmits messages within itself and to other areas of the body. The brain is composed of around 100 billion cells called neurons. Messages are sent from neuron to neuron as an electrical impulse, created by ion imbalances in neuronal membranes. Neurons are insulated by a coating known as the myelin sheath, which prevents most, but not all, of these electrical impulses from escaping. The tiny portion of the electricity which escapes from the myelin sheath can be detected and this signal can be interpreted by computers. A second feature of the brain is also key to the success of BCI: neural plasticity – the ability of the brain to adapt to new situations. Patients suffering with brain damage illustrate neural plasticity; in many cases patients are able to, over time, adapt other areas of their brain to perform the tasks of damaged regions. Neural plasticity also enables the brain to adapt to interpret new input, such as that provided by the brain-computer interface.
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