omniomni/omni-engineering huggingface dataset:
Appel reaction. The Appel reaction is an organic reaction that converts an alcohol into an alkyl chloride using triphenylphosphine and carbon tetrachloride. The use of carbon tetrabromide or bromine as a halide source will yield alkyl bromides, whereas using carbon tetraiodide, methyl iodide or iodine gives alkyl iodides. The reaction is credited to and named after Rolf Appel, it had however been described earlier. The use of this reaction is becoming less common, due to carbon tetrachloride being restricted under the Montreal protocol.

Drawbacks to the reaction are the use of toxic halogenating agents and the coproduction of organophosphorus product that must be separated from the organic product. The phosphorus reagent can be used in catalytic quantities. The corresponding alkyl bromide can also be synthesised by addition of lithium bromide as a source of bromide ions. A more sustainable version of the Appel reaction has been reported, which uses a catalytic amount of phosphine that is regenerated with oxalyl chloride.

Mechanism
The Appel reaction begins with the formation of the phosphonium salt 3, which is thought to exist as a tight ion pair with 4 and therefore is unable to undergo an alpha-elimination to give dichlorocarbene. Deprotonation of the alcohol, forming chloroform, yields an alkoxide 5. The nucleophilic displacement of the chloride by the alkoxide yields intermediate 7. With primary and secondary alcohols, the halide reacts in a SN2 process forming the alkyl halide 8 and triphenylphosphine oxide. Tertiary alcohols form the products 6 and 7 via a SN1 mechanism.

The driving force behind this and similar reactions is the formation of the strong PO double bond. The reaction is somewhat similar to the Mitsunobu reaction, where the combination of an organophosphine as an oxide acceptor, an azo compound as a hydrogen acceptor reagent, and a nucleophile are used to convert alcohols to esters and other applications like this.

Illustrative use of the Appel reaction is the chlorination of geraniol to geranyl chloride.

Modifications
The Appel reaction is also effective on carboxylic acids; this has been used to convert them to oxazolines, oxazines and thiazolines.

See also
Atherton–Todd reaction
Corey–Fuchs reaction
Mitsunobu reaction

References

Substitution reactions
Name reactions
Operative temperature. Operative temperature () is defined as a uniform temperature of an imaginary black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual nonuniform environment. Some references also use the terms 'equivalent temperature" or 'effective temperature' to describe combined effects of convective and radiant heat transfer. In design, operative temperature can be defined as the average of the mean radiant and ambient air temperatures, weighted by their respective heat transfer coefficients. The instrument used for assessing environmental thermal comfort in terms of operative temperature is called a eupatheoscope and was invented by A. F. Dufton in 1929. Mathematically, operative temperature can be shown as;

where,

 = convective heat transfer coefficient
 = linear radiative heat transfer coefficient
 = air temperature
 = mean radiant temperature

Or

 

where,

 = air velocity
 and  have the same meaning as above.

It is also acceptable to approximate this relationship for occupants engaged in near sedentary physical activity (with metabolic rates between 1.0 met and 1.3 met), not in direct sunlight, and not exposed to air velocities greater than 0.10 m/s (20 fpm).  

where  and  have the same meaning as above.

Application

Operative temperature is used in heat transfer and thermal comfort analysis in transportation and buildings. Most psychrometric charts used in HVAC design only show the dry bulb temperature on the x-axis(abscissa), however, it is the operative temperature which is specified on the x-axis of the psychrometric chart illustrated in ANSI/ASHRAE Standard 55 – Thermal Environmental Conditions for Human occupancy.

See also
HVAC
Psychrometrics
Underfloor heating
ASHRAE

References

Heating, ventilation, and air conditioning
Zymase. Zymase (also known as alcoholase) is an obsolete term for an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide. 
 It occurs naturally in yeasts. Zymase activity varies among yeast strains.

Zymase is also the brand name of the drug pancrelipase.

Cell-free fermentation experiment

Zymase was first isolated from the yeast cell in 1897 by a German chemist named Eduard Buchner who fermented sugar in the laboratory without living cells, leading to the 1907 Nobel Prize in Chemistry.

The experiment for which Buchner won the Nobel Prize consisted of producing a cell-free extract of yeast cells and showing that this "press juice" could ferment sugar. This dealt yet another blow to vitalism by showing that the presence of living yeast cells was not needed for fermentation. The cell-free extract was produced by combining dry yeast cells, quartz and diatomaceous earth and then pulverizing the yeast cells with a mortar and pestle. This mixture would then become moist as the yeast cells' contents would come out of the cells. Once this step was done, the moist mixture would be put through a press and when this resulting "press juice" had glucose, fructose, or maltose added, carbon dioxide was seen to evolve, sometimes for days. Microscopic investigation revealed no living yeast cells in the extract.

Buchner hypothesized that yeast cells secrete proteins into their environment in order to ferment sugars. It was later shown that fermentation occurs inside the yeast cells.

British chemist Sir Arthur Harden divided zymase into two varieties (dialyzable and nondialyzable) in 1905.

Some science historians suggest that Eduard Buchner, in his 1897 work, merely repeated experiments already made by Antoine Béchamp in 1857. This is not the case: what Buchner obtained with yeast zymase, and without yeast cells, was alcoholic fermentation, while Béchamp had explicitly stated that, in absence of yeast cells, and by use of what he, also, called "zymase", he obtained only sugar inversion and no alcoholic fermentation. According to K.L. Manchester, what Béchamp called "zymase" was invertase.

References 

Enzymes
John Pethica. Sir John Bernard Pethica (born 1953) is a British chemist and Science Foundation Ireland (S.F.I.) professor of material science at Trinity College, Dublin, Chief Scientific Advisor at the UK's National Physical Laboratory, and a visiting professor at Oxford University. Pethica is most noted for his work on the development of nanoindentation and atom resolution atomic force microscopy.

Education
John Pethica was a pupil at St Ambrose College, Trafford, Manchester. He received a PhD from IT Sligo in the late 1970s.

Career
In 2001, Pethica was one of the first ten people awarded an S.F.I. principal investigator award. Following the award, he transferred his activities from Oxford to Dublin.

In February 2005, it was announced that Pethica will be the director of the Naughton Institute which will house CRANN, a new purpose built nanotechnology centre in Trinity College Dublin.

In October 2007, Pethica was made the Chief Scientific Advisor at the UK's National Physical Laboratory, the UK’s National Measurement Institute.

Honours and awards
In 1999, Pethica was elected a Fellow of the Royal Society (FRS). He has also served as Vice-President and Physical Secretary of the Royal Society. He was elected a Fellow of the Royal Academy of Engineering (FREng) in 2013. He was elected an honorary fellow of St Cross College, Oxford in 2014.

Pethica was the 2001 recipient of the Hughes Medal of the Royal Society of London, and the 2002 recipient of the Holweck Prize from the Institute of Physics.

Pethica was knighted in the 2014 Birthday Honours for services to science.

Personal life
Pethica is an accomplished musician - playing violin and other instruments - with a particular interest in Irish and British folk music.

References

External links
Homepage of John Pethica at Oxford
Homepage of John Pethica at CRANN
 Chief Scientific Advisor : National Physical Laboratory

Living people
1953 births
British materials scientists
Academics of Trinity College Dublin
Fellows of the Royal Society
Alumni of Trinity Hall, Cambridge
Knights Bachelor
People educated at St. Ambrose College
Scientists of the National Physical Laboratory (United Kingdom)
Training (disambiguation). Training is the teaching of knowledge, vocational or practical matters.

Training may also refer to:

Eccentric training
Instructor-led training
Physical training:
Physical fitness training
Training as a part of Physical exercise
Animal training
Dog training
Sports training
Training (meteorology), a successive series of showers or thunderstorms moving repeatedly over the same area
Training (civil), refers to the use of structures built to constrain rivers 
Training (computer science), to initialize a machine learning system using prepared data (the training set)
 Training (gunnery), the pointing of turreted guns in a particular direction
Training (poem), a poem by Wilfred Owen
"Training" (The Office), a 2001 television episode
EPOC. EPOC may be:

 Excess post-exercise oxygen consumption
 Emotiv EPOC, consumer brain–computer interface devices for PC.
 EPOC (operating system), the precursor OS to the Symbian operating system
 Efficient Probabilistic Public-Key Encryption Scheme
 The Electric Power Optimization Centre at the University of Auckland
 EPoC - Ethernet passive optical network (EPON) Protocol over Coax
 Exploration Production and Operations Contract, a proposed NASA contract for Artemis 5 

cs:EPOC
de:EPOC
it:EPOC
nl:EPOC
pl:EPOC
pt:EPOC
ru:EPOC
sv:EPOC
American Congress on Surveying and Mapping. The American Congress on Surveying and Mapping (ACSM) was an American professional association representing the interests of those engaged in measuring and communicating geospatial data.

Originally, it was composed of four organizations:
 American Association for Geodetic Surveying (AAGS)
 National Society of Professional Surveyors (NSPS)
 Cartographic and Geographic Information Society (CaGIS)
 Geographic and Land Information Society (GLIS)
During the 2000s, CaGIS and GLIS removed themselves from ACSM; in 2012, ACSM legally merged into the NSPS, while AAGS remained separate.

It published the bimonthly ACSM Bulletin, no longer in publication.
ACSM also published the quarterly Surveying and Land Information Science (SaLIS) technical journal, now officially published by the AAGS.

See also
American Society for Photogrammetry and Remote Sensing
ALTA Survey
Canadian Institute of Geomatics
International Federation of Surveyors

References

External links
 Official website
 The American Association for Geodetic Surveying Official website
 The National Society of Professional Surveyors, Inc. Official website

Professional associations based in the United States
Surveying organizations
Geographic data and information organizations in the United States
Audi Driving Experience. The Audi Driving Experience is a national racing-track-based driving tuition and education program initiated by Audi in 1983.  Its aim is to educate drivers through both theoretical lessons and practical "hands-on" tuition, primarily focusing on the complexities of modern powertrains and chassis electronics found in virtually all of today's cars, with an emphasis on Audi vehicles.

The Audi Driving Experience includes emergency maneuvers using Anti-lock Braking System (ABS) and Electronic Stability Programme (ESP) systems, theory and practice of safe high-speed handling, and demonstrates and educates the abilities of Audi's trademark Quattro four-wheel drive system.  These activities are all carried off away from public roads and highways.

AUDI AG provides all of the vehicles at each facility.

Europe
The Audi Driving Experience originated in Audi's home country of Germany. It has its company headquarters in Ingolstadt.

United Kingdom
In the United Kingdom, it is organised by Audi UK, and is based at the Silverstone motor racing circuit.

United States
As of 2007, Audi of America and Emotive offer drivers the opportunity to drive Audi vehicles on a variety of courses.

China
Launched on 2 September 2003, the Audi Driving Experience is a driver education and training scheme offered to the Chinese motoring public.  Concentrating on three themes, or styles of driving, the courses include "defensive driving training", "advanced track training", and "winter rally training". It is based at two operational centers, operating from Shanghai and Zhuhai International Circuit.

Russia
In Russia, Audi Drive Experience is presented by the "Vasin Driving School". Spent on the race track Moscow Raceway "Audi Sport Driving Experience 2017".

Middle East
Based at the Dubai Autodrome since early 2008, the Audi Driving Experience was developed by Audi Middle East as a not-for-profit initiative.

India
The Audi Driving Experience was introduced in India with its sports car experience on 5 July 2012 at the Buddh International Circuit, Greater Noida.

References

External links

Audi.com international portal

Audi
Optical medium. In optics, an optical medium is material through which light and other electromagnetic waves propagate.  It is a form of transmission medium.  The permittivity and permeability of the medium define how electromagnetic waves propagate in it.

Properties
The optical medium has an intrinsic impedance, given by

where  and  are the electric field and magnetic field, respectively.
In a region with no electrical conductivity, the expression simplifies to:

For example, in free space the intrinsic impedance is called the characteristic impedance of vacuum, denoted Z0, and

Waves propagate through a medium with velocity , where   is the frequency and  is the wavelength of the electromagnetic waves. This equation also may be put in the form

where  is the angular frequency of the wave and  is the wavenumber of the wave. In electrical engineering, the symbol , called the phase constant, is often used instead of .

The propagation velocity of electromagnetic waves in free space, an idealized standard reference state (like absolute zero for temperature), is conventionally denoted by c0: 

where  is the electric constant and  is the magnetic constant.

For a general introduction, see Serway For a discussion of synthetic media, see Joannopoulus.

Types

 Homogeneous medium vs. heterogeneous medium
 Transparent medium vs. opaque body
 Translucent medium

See also
Čerenkov radiation
Electromagnetic spectrum
Electromagnetic radiation
Optics
SI units
Free space
Metamaterial
Photonic crystal
Photonic crystal fiber

Notes and references

Optics
Electric and magnetic fields in matter
Anglesey Aluminium. Anglesey Aluminium Metal Ltd. was a joint venture between Rio Tinto and Kaiser Aluminum. Its aluminium smelter, located on the outskirts of Holyhead, was one of the largest employers in North Wales, with 540 staff members, and began to produce aluminium in 1971. It was built on the Penrhos Estate,  of which were sold by the Stanley family for the project. Up until its closure it produced up to 142,000 tonnes of aluminium every year and was the biggest single user of electricity (255 MW) in the United Kingdom.

Alumina and coke shipped from Jamaica and Australia would berth at the company's private jetty in Holyhead harbour. This jetty is linked by a series of conveyor belts passing through tunnels to the plant. A spur rail link from the main North Wales Coast Line runs into the plant and was used for both receipt of raw materials and despatch of aluminium.

The plant was powered from the National Grid and received most of its electricity from Wylfa nuclear power station  away. Anglesey Aluminium was used as a base load for Wylfa and saved the grid the cost of keeping a power station on standby. The power contract terminated in 2009, and the aluminium smelting operation was shut down as no new contract was negotiated. The aluminium re-melt facility initially remained open after the shut down of the smelter, but its closure was announced in February 2013. The company announced tentative plans for a biomass plant on the site, but smelting operations and the plant were mothballed and the plant was finally cleared in 2023 to prepare for redevelopment. On 20 March 2024, the site's  tall chimney was demolished; the last of the visible structures of the aluminium smelting plant.

It was announced in September 2022 that the former Anglesey Aluminium site had been purchased by Stena Line, with their intention to use the site to facilitate an extension of Stena's existing operations of the Port of Holyhead. The sale included the spur rail line, the jetty in Holyhead harbour and the former conveyor tunnel linking the jetty to the main site.

Near the smelter the Aluminium Powder Company (ALPOCO) produces aluminium powder, which is used in pastes, pigments, chemicals, metallurgy, refractory, propulsion, pyrotechnics, spray deposition and powder metallurgy. Adjacent to the site is the public access Penrhos Country Park.

See also
Alcan Lynemouth Aluminium Smelter
List of aluminium smelters

References

External links
A.L.P.O.C.O.
Aerial Image of Anglesey Aluminium Plant - www.pixaerial.co.uk

Manufacturing companies of Wales
Aluminium companies of the United Kingdom
Aluminium smelters
Holyhead
Non-ferrous metallurgical works in the United Kingdom
Former Rio Tinto (corporation) subsidiaries
Former joint ventures
Kaiser Aluminum
Gibbs. Gibbs or GIBBS is a surname and acronym. It may refer to:

People
 Gibbs (surname)
 Freddie Gibbs

Places
 Gibbs (crater), on the Moon
 Gibbs, Missouri, US
 Gibbs, Tennessee, US
 Gibbs Island (South Shetland Islands), Antarctica
 2937 Gibbs, an asteroid
 Mount Gibbs

Science

Mathematics and statistics
 Gibbs phenomenon
 Gibbs' inequality
 Gibbs sampling

Physics
 Gibbs phase rule
 Gibbs free energy
 Gibbs entropy
 Gibbs paradox
 Gibbs–Helmholtz equation
 Gibbs algorithm
 Gibbs state
 Gibbs-Marangoni effect
 Gibbs phenomenon, an MRI artifact

Organisations
 Gibbs & Cox naval architecture firm
 Gothenburg International Bioscience Business School
 Gibbs College, several US locations
 Gibbs Technologies, developer and manufacturer of amphibious vehicles
 Gibbs High School (disambiguation), several schools of this name exist
 Antony Gibbs & Sons, British trading company, established in London in 1802

Other uses
 Gibbs SR, former name of the toothpaste Mentadent
 Gibbs Stadium, Spartanburg, South Carolina, US

See also

 
 
 Gibbs' Reflective Cycle
 List of things named after Josiah W. Gibbs
 Gibbes (disambiguation)
 Gibb (disambiguation)
 Gib (disambiguation)
 Gipps (disambiguation)
Vesicular texture. Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside.
 
This texture is common in aphanitic, or glassy, igneous rocks that have come to the surface of the Earth, a process known as extrusion. As magma rises to the surface the pressure on it decreases. When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles (the cavities) inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles.

A related texture is amygdaloidal in which the volcanic rock, usually basalt or andesite, has cavities, or vesicles, that are filled with secondary minerals, such as zeolites, calcite, quartz, or chalcedony. Individual cavity fillings are termed amygdules (American usage) or amygdales (British usage). Sometimes these can be sources of semi-precious or precious stones such as diamonds.

Rock types that display a vesicular texture include pumice and scoria.

See also 

 Glossary of geology

References

Volcanology
Jazz DSP. The Jazz DSP, by Improv Systems, is a VLIW embedded digital signal processor architecture with a 2-stage instruction pipeline, and single-cycle execution units. The baseline DSP includes one arithmetic logic unit (ALU), dual memory interfaces, and the control unit (instruction decoder, branch control, task control). Most aspects of the architecture, such as the number and sizes of Memory Interface Units (MIU) or the types and number of Computation Units (CU), datapath width (16 or 32-bit), the number of interrupts and priority levels, and debugging support may be independently configured using a proprietary graphical user interface (GUI) tool. A key feature of the architecture allows the user to add custom instructions and/or custom execution units to enhance the performance of their application. 

Typical Jazz DSP performance can exceed 1000 million operations per second (MOPS) at a modest 100 MHz clock frequency. Please refer to the EEMBC Benchmark site for more details on Jazz DSP performance as compared to other benchmarked processors.

Digital signal processors
Parallel computing
Very long instruction word computing
Phanerite. A phanerite is an igneous rock whose microstructure is made up of crystals large enough to be distinguished with the unaided human eye. In contrast, the crystals in an aphanitic rock are too fine-grained to be identifiable. Phaneritic texture forms when magma deep underground in the plutonic environment cools slowly, giving the crystals time to grow. 

Phanerites are often described as coarse-grained or macroscopically crystalline.

References

Phaneritic rocks
Petrology
CCGS Frederick G. Creed. CCGS Frederick G. Creed was a hydrographic survey vessel operated by the Canadian Coast Guard on behalf of the Canadian Hydrographic Service, a scientific agency of the Department of Fisheries and Oceans. The ship was built in 1988 by Swath Ocean Systems Incorporated of San Diego, California and entered service the same year. The ship was taken out of service in March 2020 and sold for scrap.

Design and description
CCGS Frederick G. Creed, constructed of aluminum, employed a SWATH system and was named after Frederick G. Creed, an inventor and pioneer of this technology. The vessel had a gross tonnage of 152 tons and was  long with a beam of  and a draught of . Frederick G. Creed was powered by two General Motors 12V92 geared diesel engines driving two shafts turning a fixed pitch propeller each. The machinery was rated at  and gave the vessel a maximum speed of . Frederick G. Creed had a range of  at  and had capacity for  of diesel fuel for an endurance of three days. Frederick G. Creed had one  dry lab aboard and carried one manually-launched rigid-hulled inflatable boat. The vessel had a complement of four personnel, composed of one officer and three crew.

Construction and service
CCGS Frederick G. Creed was built in 1988 by Swath Ocean Systems at their yard in San Diego, California. The vessel entered service with the Canadian Coast Guard in 1989 and is registered in Ottawa, Ontario and rated as a Mid Shore Science Vessel. It was homeported in Rimouski, Quebec and was used to perform surveys of the Laurentian and Maritimes regions. Frederick G. Creed was sent to Cape Hatteras to perform wave dynamic studies. In March 2020, the vessel was declared surplus and sold for scrap. Demolition was completed in December 2020.

Notes

Citations

References
 
 

Ships of the Canadian Coast Guard
Small waterplane area twin hull vessels
Ships built in San Diego
1988 ships
Military catamarans