PC Pro is one of several computer magazines published monthly in the United Kingdom by Dennis Publishing. Its headquarters is in London. PC Pro licenses individual articles for republication in various countries around the world - and some articles are translated into local languages; as of 2006, it claimed to be the biggest selling PC monthly in the UK. PC Pro is promoted as a magazine for "IT professionals, IT managers and power users." It is a fairly'rounded' magazine as it contains information on many different aspects of IT rather than just one of these areas like many UK PC magazines. While it is Windows-focused, it does contain some open source and Apple content; the magazine was launched in November 1994. The website was launched in December 1996. On 3 June 2015 Dennis relaunched the PC Pro website as Alphr; the magazine continued to operate under the PC Pro brand, with the two publications sharing content but otherwise serving different audiences with bespoke content. Each issue comes with a cover disc -- either a CD in a DVD in the £ 5.99 edition.
The CD contains complete commercial software products and commercial software trials. The DVD contains these and a selection of applications which feature in every issue; these regular applications are freeware or open source. The PC Pro team publish a weekly podcast available on the Magazine website and on the iTunes Store. In February 2001 they reissued, with new artwork, a free copy of the controversial "Area 51: The Alien Interview" DVD. Tim Danton Barry Collins David Court Darien Graham-Smith Jonathan Bray Mike Jennings Jane McCallion Sasha Muller Nicole Kobie Stewart Mitchell Jon Honeyball Davey Winder Paul Ockenden Steve Cassidy List of computer magazines PC Pro Website PC Pro Spanish Website
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are sometimes described as lava; the molten rock is formed in the interior of some planets, including Earth, some of their satellites, though such material located below the crust is referred to by other terms. A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption; when it has stopped moving, lava solidifies to form igneous rock. The term lava flow is shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows; the word lava comes from Italian, is derived from the Latin word labes which means a fall or slide.
The first use in connection with extruded magma was in a short account written by Francesco Serao on the eruption of Vesuvius in 1737. Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain; the composition of all lava of the Earth's crust is dominated by silicate minerals feldspars, pyroxenes, amphiboles and quartz. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: felsic and mafic; these classes are chemical, the chemistry of lava tends to correlate with the magma temperature, its viscosity and its mode of eruption. Felsic or silicic lavas such as rhyolite and dacite form lava spines, lava domes or "coulees" and are associated with pyroclastic deposits. Most silicic lava flows are viscous, fragment as they extrude, producing blocky autobreccias; the high viscosity and strength are the result of their chemistry, high in silica, potassium and calcium, forming a polymerized liquid rich in feldspar and quartz, thus has a higher viscosity than other magma types.
Felsic magmas can erupt at temperatures as low as 650 to 750 °C. Unusually hot rhyolite lavas, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, commonly hotter, they tend to be less viscous. Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, occasionally amphibole or pyroxene phenocrysts. Mafic or basaltic lavas are typified by their high ferromagnesian content, erupt at temperatures in excess of 950 °C. Basaltic magma is high in iron and magnesium, has lower aluminium and silica, which taken together reduces the degree of polymerization within the melt.
Owing to the higher temperatures, viscosities can be low, although still thousands of times higher than water. The low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent; the thickness of a basalt lava on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. Most basalt lavas are of pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land. Ultramafic lavas such as komatiite and magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme. Komatiites contain over 18% magnesium oxide, are thought to have erupted at temperatures of 1,600 °C.
At this temperature there is no polymerization of the mineral compounds, creating a mobile liquid. Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce magnesian magmas; some lavas of unusual composition have erupted onto the surface of the Earth. These include: Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, the sole example of an active carbonatite volcano. Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden which formed during the Proterozoic. Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile-Argentina border. Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition. Sulfur lava flows up to 250 metres 10 metres wide occur at Lastarria volcano, Chile.
They were formed by the melting of sulfur deposits at temperatures as low as 113 °C
An office is a room or other area where an organization's employees perform administrative work in order to support and realize objects and goals of the organization. The word "office" may denote a position within an organization with specific duties attached to it; when used as an adjective, the term "office" may refer to business-related tasks. In law, a company or organization has offices in any place where it has an official presence if that presence consists of a storage silo rather than an establishment with desk-and-chair. An office is an architectural and design phenomenon: ranging from a small office such as a bench in the corner of a small business of small size, through entire floors of buildings, up to and including massive buildings dedicated to one company. In modern terms an office is the location where white-collar workers carry out their functions; as per James Stephenson, "Office is that part of business enterprise, devoted to the direction and co-ordination of its various activities."
Offices in classical antiquity were part of a palace complex or of a large temple. The High Middle Ages saw the rise of the medieval chancery, the place where most government letters were written and where laws were copied in the administration of a kingdom. With the growth of large, complex organizations in the 18th century, the first purpose-built office spaces were constructed; as the Industrial Revolution intensified in the 18th and 19th centuries, the industries of banking, insurance, retail and telegraphy grew requiring a large number of clerks, as a result more office space was assigned to house their activities. The time-and-motion study, pioneered in manufacturing by F. W. Taylor led to the "Modern Efficiency Desk" of 1915 with a flat top and drawers below, designed to allow managers an easy view of the workers. However, by the middle of the 20th century, it became apparent that an efficient office required discretion in the control of privacy, the cubicle system evolved; the main purpose of an office environment is to support its occupants in performing their jobs.
Work spaces in an office are used for conventional office activities such as reading and computer work. There are nine generic types of work space, each supporting different activities. In addition to individual cubicles, one can find meeting rooms and spaces for support activities, such as photocopying and filing; some offices have a kitchen area where workers can make their lunches. There are many different ways of arranging the space in an office and whilst these vary according to function, managerial fashions and the culture of specific companies can be more important. While offices can be built in any location and in any building, some modern requirements for offices make this more difficult, such as requirements for light and security; the major purpose of an office building is to provide a workplace and working environment - for administrative and managerial workers. These workers occupy set areas within the office building, are provided with desks, PCs and other equipment they may need within these areas.
The structure and shape of the office is impacted by both management thought as well as construction materials and may or may not have walls or barriers. The word stems from the Latin officium, its equivalents in various romance, languages. An officium was not a place, but rather an mobile'bureau' in the sense of a human staff or the abstract notion of a formal position, such as a magistrature; the elaborate Roman bureaucracy would not be equaled for centuries in the West after the fall of Rome partially reverting to illiteracy, while the East preserved a more sophisticated administrative culture, both under Byzantium and under Islam. Offices in classical antiquity were part of a palace complex or a large temple. There was a room where scrolls were kept and scribes did their work. Ancient texts mentioning the work of scribes allude to the existence of such "offices"; these rooms are sometimes called "libraries" by some archaeologists and the general press because one associates scrolls with literature.
In fact they were true offices since the scrolls were meant for record keeping and other management functions such as treaties and edicts, not for writing or keeping poetry or other works of fiction. The High Middle Ages saw the rise of the medieval chancery, the place where most government letters were written and where laws were copied in the administration of a kingdom; the rooms of the chancery had walls full of pigeonholes, constructed to hold rolled up pieces of parchment for safekeeping or ready reference, a precursor to the bookshelf. The introduction of printing during the Renaissance did not change these early government offices much. Medieval illustrations, such as paintings or tapestries show people in their private offices handling record-keeping books or writing on scrolls of parchment. All kinds of writings seemed to be mixed in these early forms of offices. Before the invention of the printing press and its distribution there was a thin line between a private office and a private library since books were read or written in the same space at the same desk or table, general accounting and personal or private letters were done there.
It was during the 13th century that the English form of the word first appeared w
A nanostructure is a structure of intermediate size between microscopic and molecular structures. Nanostructural detail is microstructure at nanoscale. In describing nanostructures, it is necessary to differentiate between the number of dimensions in the volume of an object which are on the nanoscale. Nanotextured surfaces have one dimension on the nanoscale, i.e. only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have two dimensions on the nanoscale, i.e. the diameter of the tube is between 0.1 and 100 nm. Spherical nanoparticles have three dimensions on the nanoscale, i.e. the particle is between 0.1 and 100 nm in each spatial dimension. The terms nanoparticles and ultrafine particles are used synonymously although UFP can reach into the micrometre range; the term nanostructure is used when referring to magnetic technology. Nanoscale structure in biology is called ultrastructure. Properties of nanoscale objects and ensembles of these objects are studied in physics.
Nanomaterials Nanotechnology Tube-based nanostructures List of software for nanostructures modeling Nano Flakes May Revolutionize Solar Cells Applications of Nanoparticles
The micrometre or micrometer commonly known by the previous name micron, is an SI derived unit of length equalling 1×10−6 metre. The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, for grading wool by the diameter of the fibres; the width of a single human hair ranges from 10 to 200 μm. The longest human chromosome is 10 μm in length. Between 1 μm and 10 μm: 1–10 μm – length of a typical bacterium 10 μm – Size of fungal hyphae 5 μm – length of a typical human spermatozoon's head 3–8 μm – width of strand of spider web silk about 10 μm – size of a fog, mist, or cloud water droplet Between 10 μm and 100 μm about 10–12 μm – thickness of plastic wrap 10 to 55 μm – width of wool fibre 17 to 181 μm – diameter of human hair 70 to 180 μm – thickness of paper The term micron and the symbol μ were accepted for use in isolation to denote the micrometre in 1879, but revoked by the International System of Units in 1967; this became necessary because the older usage was incompatible with the official adoption of the unit prefix micro-, denoted μ, during the creation of the SI in 1960.
In the SI, the systematic name micrometre became the official name of the unit, μm became the official unit symbol. In practice, "micron" remains a used term in preference to "micrometre" in many English-speaking countries, both in academic science and in applied science and industry. Additionally, in American English, the use of "micron" helps differentiate the unit from the micrometer, a measuring device, because the unit's name in mainstream American spelling is a homograph of the device's name. In spoken English, they may be distinguished by pronunciation, as the name of the measuring device is invariably stressed on the second syllable, whereas the systematic pronunciation of the unit name, in accordance with the convention for pronouncing SI units in English, places the stress on the first syllable; the plural of micron is "microns", though "micra" was used before 1950. The official symbol for the SI prefix micro- is a Greek lowercase mu. In Unicode, there is a micro sign with the code point U+00B5, distinct from the code point U+03BC of the Greek letter lowercase mu.
According to the Unicode Consortium, the Greek letter character is preferred, but implementations must recognize the micro sign as well. Most fonts use the same glyph for the two characters. Metric prefix Metric system Orders of magnitude Wool measurement The dictionary definition of micrometre at Wiktionary
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, petrol, biodiesel blends, diesel fuel, fuel oil, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle, it disperses downwind in a pattern called an exhaust plume. It is a major component of motor vehicle emissions, which can include: Crankcase blow-by Evaporation of unused gasolineMotor vehicle emissions contribute to air pollution and are a major ingredient in the creation of smog in some large cities. A 2013 study by MIT indicates that 53,000 early deaths occur per year in the United States alone because of vehicle emissions. According to another study from the same university, traffic fumes alone cause the death of 5,000 people every year just in the United Kingdom; the largest part of most combustion gas is nitrogen, water vapor, carbon dioxide. A small part of combustion gas is undesirable, noxious, or toxic substances, such as carbon monoxide from incomplete combustion, hydrocarbons from unburnt fuel, nitrogen oxides from excessive combustion temperatures, particulate matter.
Exhaust gas temperature is important to the functioning of the catalytic converter of an internal combustion engine. It may be measured by an exhaust gas temperature gauge. EGT is a measure of engine health in gas-turbine engines. During the first two minutes after starting the engine of a car that has not been operated for several hours, the amount of emissions can be high; this occurs for two main reasons: Rich air-fuel ratio requirement in cold engines: When a cold engine is started, the fuel does not vaporize creating higher emissions of hydrocarbons and carbon monoxide, which diminishes only as the engine reaches operating temperature. The duration of this start-up phase has been reduced by advances in materials and technology, including computer-controlled fuel injection, shorter intake lengths, pre-heating of fuel and/or inducted air. Inefficient catalytic converter under cold conditions: Catalytic converters are inefficient until up to their operating temperature; this time has been much reduced by moving the converter closer to the exhaust manifold and more so placing a small yet quick-to-heat-up converter directly at the exhaust manifold.
The small converter handles the start-up emissions, which allows enough time for the larger main converter to heat up. Further improvements can be realised in many ways, including electric heating, thermal battery, chemical reaction preheating, flame heating and superinsulation. Comparable with the European emission standards EURO III as it was applied on October 2000 In 2000, the United States Environmental Protection Agency began to implement more stringent emissions standards for light duty vehicles; the requirements were phased in beginning with 2004 vehicles and all new cars and light trucks were required to meet the updated standards by the end of 2007. In spark-ignition engines the gases resulting from combustion of the fuel and air mix are called exhaust gases; the composition varies from petrol to diesel engines, but is around these levels: The 10% oxygen for "diesel" is if the engine was idling, e.g. in a test rig. It is much less. Exhaust gas from an internal combustion engine whose fuel includes nitromethane will contain nitric acid vapour, corrosive, when inhaled causes a muscular reaction making it impossible to breathe.
People exposed to it should wear a gas mask. In aircraft gas turbine engines, "exhaust gas temperature" is a primary measure of engine health; the EGT is compared with a primary engine power indication called "engine pressure ratio". For example: at full power EPR there will be a maximum permitted EGT limit. Once an engine reaches a stage in its life where it reaches this EGT limit, the engine will require specific maintenance in order to rectify the problem; the amount the EGT is below the EGT limit is called EGT margin. The EGT margin of an engine will be greatest when the engine has been overhauled. For most airlines, this information is monitored remotely by the airline maintenance department by means of ACARS. In jet engines and rocket engines, exhaust from propelling nozzles which in some applications shows shock diamonds. Flue gas Flue gas emissions from fossil fuel combustion In steam engine terminology the exhaust is steam, now so low in pressure that it can no longer do useful work. Mono-nitrogen oxides NO and NO2 react with ammonia and other compounds to form nitric acid vapor and related particles.
Small particles can penetrate into sensitive lung tissue and damage it, causing premature death in extreme cases. Inhalation of NO species increases the risk of colorectal cancer, and inhalation of such particles may cause or worsen respiratory diseases such as emphysema and bronchitis and heart disease. In a 2005 U. S. EPA study the largest emissions of NOx came from on road motor vehicles, with the second largest contributor being non-road equipment, gasoline and diesel stations; the resulting nitric acid may be washed into soil, where it becomes nitrate, useful to growing plants. When oxides of nitrogen and volatile organic compounds react in the presence of sunlight, ground l
Nanoparticles are particles between 1 and 100 nanometres in size with a surrounding interfacial layer. The interfacial layer is an integral part of nanoscale matter, fundamentally affecting all of its properties; the interfacial layer consists of ions and organic molecules. Organic molecules coating inorganic nanoparticles are known as stabilizers and surface ligands, or passivating agents. In nanotechnology, a particle is defined as a small object that behaves as a whole unit with respect to its transport and properties. Particles are further classified according to diameter; the term "nanoparticle" is not applied to individual molecules. Ultrafine particles are the same as nanoparticles and between 1 and 100 nm in size, as opposed to fine particles are sized between 100 and 2,500 nm, coarse particles cover a range between 2,500 and 10,000 nm; the reason for the synonymous definition of nanoparticles and ultrafine particles is that, during the 1970s and 80s, when the first thorough fundamental studies with "nanoparticles" were underway in the USA and Japan, they were called "ultrafine particles".
However, during the 1990s before the National Nanotechnology Initiative was launched in the USA, the new name, "nanoparticle," had become more common. Nanoparticles can exhibit size-related properties different from those of either fine particles or bulk materials. Nanoclusters have at least one dimension a narrow size distribution. Nanopowders nanoparticles, or nanoclusters. Nanometer-sized single crystals, or single-domain ultrafine particles, are referred to as nanocrystals. According to ISO Technical Specification 80004, a nanoparticle is defined as a nano-object with all three external dimensions in the nanoscale, whose longest and shortest axes do not differ with a significant difference being a factor of at least 3; the terms colloid and nanoparticle are not interchangeable. A colloid is a mixture; the term applies only if the particles are larger than atomic dimensions but small enough to exhibit Brownian motion, with the critical size range ranging from nanometers to micrometers. Colloids can contain particles too large to be nanoparticles, nanoparticles can exist in non-colloidal form, for examples as a powder or in a solid matrix.
Although nanoparticles are associated with modern science, they have a long history. Nanoparticles were used by artisans as far back as Rome in the fourth century in the famous Lycurgus cup made of dichroic glass as well as the ninth century in Mesopotamia for creating a glittering effect on the surface of pots. In modern times, pottery from the Middle Ages and Renaissance retains a distinct gold- or copper-colored metallic glitter; this luster is caused by a metallic film, applied to the transparent surface of a glazing. The luster can still be visible if the film has resisted other weathering; the luster originates within the film itself, which contains silver and copper nanoparticles dispersed homogeneously in the glassy matrix of the ceramic glaze. These nanoparticles are created by the artisans by adding copper and silver salts and oxides together with vinegar and clay on the surface of previously-glazed pottery; the object is placed into a kiln and heated to about 600 °C in a reducing atmosphere.
In heat the glaze softens, causing the copper and silver ions to migrate into the outer layers of the glaze. There the reducing atmosphere reduced the ions back to metals, which came together forming the nanoparticles that give the color and optical effects. Luster technique showed; the technique originated in the Muslim world. As Muslims were not allowed to use gold in artistic representations, they sought a way to create a similar effect without using real gold; the solution they found was using luster. Michael Faraday provided the first description, in scientific terms, of the optical properties of nanometer-scale metals in his classic 1857 paper. In a subsequent paper, the author points out that: "It is well known that when thin leaves of gold or silver are mounted upon glass and heated to a temperature, well below a red heat, a remarkable change of properties takes place, whereby the continuity of the metallic film is destroyed; the result is that white light is now transmitted, reflection is correspondingly diminished, while the electrical resistivity is enormously increased."
Nanoparticles are of great scientific interest as they are, in effect, a bridge between bulk materials and atomic or molecular structures. A bulk material should have constant physical properties regardless of its size, but at the nano-scale size-dependent properties are observed. Thus, the properties of materials change as their size approaches the nanoscale and as the percentage of the surface in relation to the percentage of the volume of a material becomes significant. For bulk materials larger than one micrometer, the percentage of the surface is insignificant in relation to the volume in the bulk of the material; the interesting and sometimes unexpected properties of nanoparticles are therefore due to the large surface area of the material, which dominates the contributions made by the small bulk of the material. Nanoparticles possess unexpected optical properties as they are small enough