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As defined by Park & Lakes (2007), a biomaterial is a material that replaces either a tissue within the body or a function of the body.

In the first generation of biomaterial development, individuals used materials in their local environments for replacing tissues that were lost to damage or disease.

The goal during the first generation of biomaterial development was the creation of materials that exhibited inert behaviour when placed in the body. Surgeons sought materials that provided (i) appropriate mechanical properties for the intended use, (ii) corrosion resistance, and (iii) an absence of injurious effects such as carcinogenicity, toxicity, allergy and inflammation.

Most current bactericidal antimicrobials, which are the focus of this review, inhibit DNA synthesis, RNA synthesis, cell wall synthesis, or protein synthesis

Quinolones are derivatives of nalidixic acid, which was discovered as a byproduct of chloroquine (quinine) synthesis

Nalidixic acid and other first generation quinolones (i.e., oxolinic acid) are rarely used today owing to their toxicity17. Second (i.e., ciprofloxacin), third (i.e., levofloxacin) and fourth (i.e., gemifloxacin) generation quinolone antibiotics (Table 1) can be classified based on their chemical structure along with qualitative differences in how these drugs kill bacteria

A nuclear rocket engine uses a nuclear reactor to heat hydrogen to very high temperatures, which expands through a nozzle to generate thrust.

The team recently used Marshall's Nuclear Thermal Rocket Element Environmental Simulator, or NTREES, to perform realistic, non-nuclear testing of various materials for nuclear thermal rocket fuel elements. In an actual reactor, the fuel elements would contain uranium, but no radioactive materials are used during the NTREES tests. Among the fuel options are a graphite composite and a "cermet" composite - a blend of ceramics and metals. Both materials were investigated in previous NASA and U.S. Department of Energy research efforts.

A first-generation nuclear cryogenic propulsion system could propel human explorers to Mars more efficiently than conventional spacecraft, reducing crews' exposure to harmful space radiation and other effects of long-term space missions. It could also transport heavy cargo and science payloads. Further development and use of a first-generation nuclear system could also provide the foundation for developing extremely advanced propulsion technologies and systems in the future - ones that could take human crews even farther into the solar system.

roject Orion was the first serious attempt to design a nuclear pulse rocket. The design effort was carried out at General Atomics in the late 1950s and early 1960s. The idea of Orion was to react small directional nuclear explosives against a large steel pusher plate attached to the spacecraft with shock absorbers. Efficient directional explosives maximized the momentum transfer, leading to specific impulses in the range of 6,000 seconds, or about 12 times that of the Space Shuttle Main Engine. With refinements, a theoretical maximum of 100,000 seconds (1 MN·s/kg) might be possible. Thrusts were in the millions of tons, allowing spacecraft larger than eight million tons to be built with 1958 materials.

The reference design was to be constructed of steel using submarine-style construction, with a crew of more than 200 and a vehicle takeoff weight of several thousand tons. This low-tech single-stage reference design would reach Mars and back in four weeks from the Earth’s surface (compared to ≈50 weeks for NASA’s current chemically powered reference mission). The same craft could visit Saturn’s moons in a seven-month mission (compared to chemically powered missions of about nine years).

A number of engineering problems were found, and solved, over the course of the project. Many of these related to crew shielding and pusher-plate lifetime. The system appeared to be entirely workable, and was under serious development in the United States, when the project was shut down in 1965. The primary reason given was that the Partial Test Ban Treaty made it illegal to detonate nuclear explosions in space (before the treaty, the United States and the Soviet Union had already detonated at least nine nuclear bombs, including thermonuclear bombs, in space; i.e., at altitudes over 100 km).

produced a nine-minute animation

with a limited income, most people will choose to take care of their own immediate needs before they address the needs of the planet.

Between 1977 and 2013, the overall cost associated with solar power dropped an amazing 99%

dropped 60% since the beginning of 2011

Neurotransmitters are formed in a presynaptic neuron and stored in small membrane-bound sacks, called vesicles , inside this neuron. When this neuron is activated, these intracellular vesicles fuse with the cell membrane and release their contents into the synapse, a process called exocytosis.

toxic levels of lead, cadmium, antimony and phthalates, said this year's "Trouble in Toyland" report from the U.S. Public Interest Research Group (PIRG).

f antimony, a toxic metal that has been classified as a cancer-causing agent.

Phthalates are chemicals suspected to cause developmental health effects. Cadmium is a toxic metal that can cause learning disabilities and kidney problems.

Humans normally absorb cadmium into the body either by ingestion or inhalation Dermal exposure (uptake through the skin) is generally not regarded to be of significance

2% to 6% of the cadmium ingested is actually taken up into the body. Factors influencing cadmium absorption are the form in which cadmium is present in the food, and the iron status of the exposed individual. In contrast, from 30% to 64% of inhaled cadmium is absorbed by the body, with some variation as a function of chemical form, solubility and particle size of the material inhaled.

a greater proportion of inhaled cadmium is retained by the body than when cadmium is taken in by ingestion.

generated more energy from fusion reactions than they put into the nuclear fuel,

The ultimate goal – to produce more energy than the whole experiment consumes – remains a long way off

with zero carbon emissions during operation and minimal waste