Plutonium (Worlds Most Dangerous Element )

             Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-white appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen and silicon. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that can spontaneously ignite. It is also a radioactive poison that accumulates in bone marrow. These and other properties make the handling of plutonium dangerous.

Plutonium is the heaviest primordial element, by virtue of its most stable isotope, plutonium-244, whose half-life of about 80 million years is just long enough for the element to be found in trace quantities in nature.

The most important isotope of plutonium is plutonium-239, with a half-life of 24,100 years. Plutonium-239 is the isotope most useful for nuclear weapons. Plutonium-239 and 241 are fissile, meaning the nuclei of their atoms can break apart by being bombarded by slow moving thermal neutrons, releasing energy, gamma radiation and more neutrons. These can therefore sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors.

Plutonium-238 has a half-life of 88 years and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, which are used to power some spacecraft.

Plutonium-240 has a high rate of spontaneous fission, raising the neutron flux of any sample it is in. The presence of plutonium-240 limits a sample's usability for weapons or reactor fuel, and determines its grade.

General properties

Name, symbol, number               plutonium, Pu, 94

Element category                               actinide

Group, period, block                       n/a, 7, f

Standard atomic weight               (244)g·mol−1

Electron configuration                       [Rn] 5f6 7s2

Electrons per shell                       2, 8, 18, 32, 24, 8, 2 (Image)

Physical properties

Phase                                               solid

Density (near r.t.)                               19.816 g·cm−3

Liquid density at m.p.                       16.63 g·cm−3

Melting point                                       912.5 K, 639.4 °C, 1182.9 °F

Boiling point                                       3505 K, 3228 °C, 5842 °F

Heat of fusion                               2.82 kJ·mol−1

Heat of vaporization                       333.5 kJ·mol−1

Specific heat capacity                       (25 °C) 

35.5 J·mol−1·K−1

 

Bacteria

Bacteria are a large group of single-celled, prokaryote microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×1030) bacteria on Earth, forming much of the world's biomass.Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most bacteria have not been characterised, and only about half of the phyla of bacteria have species that can be grown in the laboratory.The study of bacteria is known as bacteriology, a branch of microbiology.

There are approximately ten times as many bacterial cells in the human flora as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora.The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague. The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, bacteria are important in sewage treatment, the production of cheese and yogurt through fermentation, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.

Motorola Xoom

Features

• Android 3.0
• 10.1 inch display
• Dual Core 1 Ghz CPU NVIDIA Tegra 2
• 1GB RAM
• 32 GB inbuilt memory with microSD Card slot
• 10 hr video playback battery life
• 5 MP Rear camera with Flash and  720p HD video capture
• 2MP video calling camera
• Wifi(n) Bluetooth 2.1, 3G , 4G

Motorola XOOM Tablet

OS                                   Android 3.0 Honeycomb

Differentiation            Larger display in smaller form-factor, 1080p HD support, first tablet with Honeycomb software, dual-core 1GHz processor, and a wide range of docking options

Dimensions                  249.1mm (h) x 167.8mm (w) x 12.9mm (d)

Display                        10.1” 1280×800 resolution

Weight                    730 g

Processor                   NVIDIA® Tegra™ 2: 1GHz dual-core processor

Battery                       Up to 10 hour video playback

Connectivity           3.5mm, micro USB 2.0 HS, Corporate Sync, Wi-Fi 2.4GHz & 5GHz 802.11b/g/n, Bluetooth 2.1 + EDR + HID

Network 3 G, 4G LTE upgradeable, 802.11n w/Personal Hotspot

Messaging/Web/Apps Email (Corporate Sync, Google Mail, POP3/IMAP embedded, Push Email, Yahoo Mail) , WebKit w/ Flash

Audio AAC, AAC+, AMR NB, AMR WB, MP3, XMF

Video 720p capture/1080p playback/streaming, H.263, H.264, MPEG4

Camera 5 MP rear-facing camera with dual LED flash/2MP front-facing camera

Memory 32GB on board user memory, SD card support after software update, 1GB DDR2 RAM

Nanotechnology

vanadium(IV) oxide

Nanotechnology (sometimes shortened to "nanotech") is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with structures sized between 1 to 100 nanometer in at least one dimension, and involves developing materials or devices within that size. Quantum mechanical effects are very important at this scale, which is in the quantum realm.
Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale.

There is much debate on the future implications of nanotechnology. Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production. On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nanomaterials, and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.
Nanoparticle 
In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Particles are further classified according to size: in terms of diameter, fine particles cover a range between 100 and 2500 nanometers. On the other hand, ultrafine particles are sized between 1 and 100 nanometers. Similar to ultrafine particles, nanoparticles are sized between 1 and 100 nanometers. Nanoparticles may or may not exhibit size-related properties that differ significantly from those observed in fine particles or bulk materials.Although the size of most molecules would fit into the above outline, individual molecules are usually not referred to as nanoparticles.

(a, b, and c) images of prepared mesoporous silica nanoparticles with mean outer diameter: (a) 20nm, (b) 45nm, and (c) 80nm. SEM (d) image corresponding to (b). The insets are a high magnification of mesoporous silica particle.