Portal:Technology

Selected article

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide. For example: a carbon-14 atom (the "parent") emits radiation and transforms to a nitrogen-14 atom (the "daughter"). This is a random process on the atomic level, in that it is impossible to predict when a given atom will decay, but given a large number of similar atoms the decay rate, on average, is predictable.

The SI unit of radioactive decay is the becquerel (Bq). One Bq is defined as one transformation (or decay) per second. Since any reasonably-sized sample of radioactive material contains many atoms, a Bq is a tiny measure of activity; amounts on the order of TBq (terabecquerel) or GBq (gigabecquerel) are commonly used. Another unit of radioactivity is the curie, Ci, which was originally defined as the activity of one gram of pure radium, isotope Ra-226. At present it is equal, by definition, to the activity of any radionuclide decaying with a disintegration rate of 3.7 í— 10¹⁰ Bq. The use of Ci is presently discouraged by the SI.

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Selected picture

Credit: Cmmmm

Scanning tunneling microscopy (STM) is a powerful technique for viewing surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer (at IBM Zí¼rich), the Nobel Prize in Physics in 1986^[1]. STM probes the density of states of a material using tunneling current. For STM, good resolution is considered to be 0.1 nm lateral resolution and 0.01 nm depth resolution^[2]. The STM can be used not only in ultra high vacuum but also in air and various other liquid or gas ambients, and at temperatures ranging from near 0 kelvin to a few hundred degrees Celsius^[3].

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News

Wikinews Science and technology portal

• March 10: Man jailed after Facebook murder case in County Durham, England
• March 7: Paleontologists reaffirm the cause of dino extinction
• March 7: 10 billionth update placed on social networking website Twitter
• March 4: US reveals Internet security efforts
• March 3: Apple sues Taiwanese mobile phone maker HTC
• February 26: Russian Wikipedia reaches half a million articles
• February 14: Chip and PIN 'not fit for purpose', says Cambridge researcher
• February 14: Chicago Metra considers selling naming rights for train lines, stations
• February 13: Airborne laser successfully destroys ballistic missile
• February 10: Google introduces Google Buzz

Did you know...

• ... that both the Mozilla Firefox and Microsoft Internet Explorer web browser design ideas descended from the Mosaic web browser?

• ... that a coherer, hot wire barretter, electrolytic detector, cat's whisker and vacuum tube were all types of radio detectors?

• ... that in 2008 Hewlett-Packard created a prototype of the theoretical fourth and last passive circuit element, the memristor, that may one day revolutionize electronics, although the theory was devised in 1971?

• ... that a mercury arc rectifier converts alternating current to direct current by means of an electric arc through mercury vapor?

• ... that only one of the 266 1076 Class steam locomotives built for the Great Western Railway was named, and the rest had only numbers?

• ... that the six Charles Tayleur locomotives ordered by Isambard Kingdom Brunel for the Great Western Railway were unsuccessful?

• ... that the intensity of a tropical cyclone (pictured) is usually determined by the Dvorak technique using only visible and infrared satellite images?

• ... that the technique of double-balloon enteroscopy allows any position along the gastrointestinal tract to be visualized in real-time?

Lists of basic topics   (all)

Main outlines: Outline of science and Outline of technology

Applied science

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Business management

Actuarial science - Marketing - Manufacturing

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Energy

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Industry

Architecture

Construction

Machines

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Mining

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Design

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Telecommunication

Radio

Military science

Martial arts

Transport

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Vehicles

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Notes

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Main categories: Technology and Applied sciences

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Technology timelines

Topics   (all)

Glossaries   (all)

Air pollution dispersion terminology - Blogging - Broadcasting - Computing and IT (Alternative terms for free software - Computer - Fisheries - Fuel cell terms - Internet - Legal terms - Object-oriented programming - Unified Modeling Language) - Firefighting (Equipment - Wildland fires) - Library and information science - Machine vision - Metalworking terminology - Mill machinery - Nautical - Telephony - Textile manufacturing - Transport (Aviation, aerospace, and aeronautics - Automotive design - Rail (Passenger rail - NZ railfan - UK railfan - U.S. railfan) ) - Woodworking (Joinery) - Winemaking

Related portals   (all)

Technology and applied sciences

Agriculture - Agronomy - Architecture (Bridges, Portal) - Biotechnology - Electronics - Energy (Renewable energy) - Engineering - Hazardous Materials - Home improvement - Nanotechnology - Nuclear technology - Robotics

Information technology

Apple Inc. - Blu-ray - Computer networking (Internet (Forums)) - Computer science (Artificial intelligence) - Computer security (Cryptography) - Google - Microsoft - Java - Python programming - Software (Free software (Linux)) - Telecommunication - Typography

Transport

Aviation - Cars (Australian, Japanese) - Bicycles/Cycling - London transport - Nautical - Roads (U.S. Roads) - Spaceflight (Human spaceflight) - Trains (Rapid transit, UK Railways, UK Trams) - UK Waterways

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