omniomni/omni-engineering huggingface dataset:
Republic XP-69. The Republic XP-69 was an American fighter aircraft proposed by Republic Aviation in 1941 in response to a requirement by the United States Army Air Corps for a high-speed fighter. Manufacturers were encouraged to consider unorthodox designs; although the design was ordered as a prototype it was canceled because of delays with the engine that was to power it.

Development 
The United States Army Air Corps began the R40-C fighter competition in February 1940. The competition encouraged manufacturers to propose unorthodox high-speed fighter aircraft that met the requirements of Type Specification XC-622.  The specification called for a single-engined high-performance fighter aircraft, with a maximum speed between , armed with both machine guns and cannons, and be capable of landing on a  long grass runway.

Republic was one of six companies selected for the competition, and one of the aircraft proposed to the USAAC by Republic was the AP-12 Rocket. As proposed, the AP-12 was to be powered by a 2,500 hp Wright R-2160-3 Tornado 42-cylinder liquid-cooled radial engine mounted in the mid-section of the aircraft's streamlined, cigar-shaped fuselage, behind the cockpit, which drove a pair of three-bladed contra-rotating propellers.  It was to be armed with four nose-mounted machine guns firing through the propeller arc, and a single 20 mm cannon firing through the propeller hub.  The AP-12 placed 13th out of 26 contestants, forcing Republic to go back to the drawing board to improve its proposal.

In July 1941, Republic submitted an improved design, the AP-18. The AP-18 had little in common with the AP-12. It retained the original aircraft's R-2160 engine, which was now mounted in the nose of a completely new small-cross section airframe.  The large radiator was to be mounted under the fuselage. The pressurized cockpit was to feature a bubble canopy, and an armament of four .50 in machine guns and two 37 mm cannons mounted in a laminar flow wing was planned.

In December 1941, the United States Army Air Forces (successor to the USAAC) ordered two prototypes of the AP-18 under the designation XP-69.  A mockup was built and was inspected by the USAAF in June 1942.  Construction of the first prototype began in November of that year.  However, due to development troubles and delays with the R-2160 engine, the XP-69 project was canceled in favor of a parallel development, the Republic XP-72, on May 24, 1943. By that time engineering on the project was 75% complete and the prototype was still in the early stages of construction, with the total program cost being $810,000.

Specifications (XP-69 as planned)

See also

References 

Republic aircraft
1940s United States fighter aircraft
Single-engined tractor aircraft
Aircraft with contra-rotating propellers
Low-wing aircraft
Cancelled military aircraft projects of the United States
Aircraft with retractable conventional landing gear
Single-engined piston aircraft
Diagonal pliers. Diagonal pliers (also known as wire cutters or diagonal cutting pliers, or under many regional names) are pliers intended for the cutting of wire or small stock, rather than grabbing or turning. The plane defined by the cutting edges of the jaws intersects the joint rivet at an angle or "on a diagonal", giving pliers their name.

They are also adapted for use in inaccessible places.

Action 
Instead of using a shearing action as with scissors, diagonal pliers cut by indenting and wedging the wire apart.  The jaw edges are ground to a symmetrical "V" shape, thus the two jaws can be visualized to form the letter "X", as seen end-on when closed.  The blades are made of tempered steel, and inductive heating and quenching are often used to harden the jaws.

Jargon 
In UK English and Irish English, diagonal pliers are commonly referred to as snips, nippers or side cutters. The term snips commonly refers to larger items, not to those used for cutting electrical wiring etc. In Canada, Australia and New Zealand too, the items are often referred to as side cutters.

Diags, dykes or dikes is jargon used especially in the US electrical industry to describe diagonal pliers. "Dike" can also be used (but only colloquially) as a verb, as in the phrase "when in doubt, dike it out".

Insulation 
The handles of diagonal cutting pliers are commonly insulated with a dip-type or shrink fit electrically insulating material for comfort and some protection against electric shock.

Uses 
Diagonal pliers are useful for cutting copper, brass, iron, aluminium and steel wire. Lower quality versions are generally not suitable for cutting tempered steel, such as piano wire, as the jaws are not hard enough. Attempting to cut such material will usually cause indentations to be made in the jaws, or a piece to break out of one or both jaws, thus ruining the tool. However higher quality side cutters can cut hardened steel, such as 2 mm piano wire.

Variations 

For electronics work, special diagonal cutters that are ground flush to the apex of the cutting edge on one side of the jaws are often used.  These flush-cutting pliers allow wires to be trimmed flush or nearly flush to a solder joint, avoiding the sharp tip left by symmetrical diagonal cutters.  It is common for this type of diagonal cutter to be referred to by another name, such as flush cutter to distinguish it from symmetrical cutters.

For easier cutting of larger gauge wire, a compound action can be employed to increase the mechanical advantage.

Some pliers for electrical work are fitted with wire-cutter blades either built into the jaws or on the handles just below the pivot.

Other variations are made to create high leverage specifically to cut through hard wire, such as electrical fence wire, dental wire, and piano wire.

Gallery

References

Pliers
Cutting tools
GWR 2600 Class. The Great Western Railway (GWR) 2600 or Aberdare class was a class of 2-6-0 steam locomotive built between 1900 and 1907. They were a freight and light mineral development of the 3300 Bulldog and 4100 Badminton classes, both 4-4-0 locomotives. Therefore, the design was adapted and became a 2-6-0 type; the resulting locomotives were used for hauling coal trains between Aberdare and Swindon.

Numbering
The class began in 1900 with a prototype, No. 33, renumbered 2600 in 1912. The rest were numbered 2601–2680 and were built between 1901 and 1907.

British Railways
British Railways (BR) inherited nos. 2612/20/3/43/51/5/6/62/5/7/9/80 in 1948. By 31 August 1948, only four were left: nos. 2620, 2651, 2655, 2667.

Withdrawal

They were withdrawn from 1934 onwards. Five Aberdares (2640, 2648, 2649, 2652 & 2657) withdrawn in early 1939 were not cut up but stored as Second World War reserves. These five reentered service by January 1940. Their withdrawal began again in 1944 until the last member, number 2667, was withdrawn in October 1949. No examples were preserved.

References

External links 

 2600 'Aberdare' class

2600
2-6-0 locomotives
Railway locomotives introduced in 1900
Standard gauge steam locomotives of Great Britain
Scrapped locomotives
Freight locomotives
GWR 6400 Class. The Great Western Railway (GWR) 6400 Class is a class of 0-6-0 pannier tank steam locomotive introduced by Charles Collett in 1932. All 40 examples were 'auto-fitted' – equipped with the remote-control equipment needed for working autotrains.

The 1936 GWR 7400 Class was a similar class, without the autotrain apparatus, but with a higher boiler pressure of 180 psi, providing a small but useful increase in power. An initial build of 30 in 1936-1937 was added to by British Railways in two batches each of ten locos in 1948 and 1950. These were destined for a short life, the briefest being only nine years. A minor visual difference between the 5400 and earlier 6400, and the later series of 6400, with the 7400 classes was at the join between cab and bunker. The 5400 and early 6400 had an arc whereas the later 6400 and the 7400 class was straight. The early locos also had a lip at the leading edge of the cab roof, whereas the later locos had a plain corner edge.

Both classes were closely related to the 1930 GWR 5400 Class, which was in turn an evolution of both the Armstrong 1874 GWR 850 Class and the Dean 1891 GWR 2021 Class. Thus the basic design was almost sixty years old when new, the  driving wheels being the main distinguishing factor, apart from the more modern profile. There were also superficial similarities with the GWR 645 Class as extant in the 1930s, that also had  wheels and  stroke cylinders (and by then pannier tanks and full cabs).

Operations
The smaller wheels of the 6400's permitted operation in hillier locations than the 5400 Class and allocations were initially to the South Wales valleys.

Engines of class 6400 worked on many of the ex-GWR branch lines in Devon and around Plymouth until the early 1960s, when the lines closed or diesel multiple units took over services. No. 6430 was a regular engine on the old Tavistock South branch line and would often run with two autocoaches. No. 6412 was allocated at Gloucester Horton Rd loco shed (85B) and operated one of the last 'Chalford Railcar' autotrain services between Gloucester and Chalford on 31 October 1964.

Being allocated to Plymouth Laira the type was trialled on the former Lostwithiel and Fowey Railway, although a 1400 Class 0-4-2 engine was normally used.

Withdrawal
The below list shows when all of the original 6400's and later 7400's were withdrawn from service. The members of the GWR 6400 Class and the GWR 7400 Class were No. 6419 and No. 7439 respectively.

Preservation

Three of the 6400 Class have survived to preservation:

See also
 GWR 0-6-0PT – list of classes of GWR 0-6-0 pannier tank, including table of preserved locomotives

References

External links 

 No. 6412 at the South Devon Railway
 No. 6430 at the Llangollen Railway
 No. 6435 at the Bodwin & Wenford Railway 
 Guide to GWR Pannier Tank Classes

0-6-0PT locomotives
6400
Railway locomotives introduced in 1932
Standard gauge steam locomotives of Great Britain
Passenger locomotives
Go/no-go. A go/no-go test is a two-step verification process that uses two boundary conditions, or a binary classification. The test is passed only when the go condition has been met and also the no-go condition has failed.

The test gives no information as to the degree of conformance to, or deviation from the boundary conditions. These tests can be used for statistical process control purposes.  There are specific SPC tools that use parameter based measurements (e.g., P-charts) for determining the stability of a process.

It has uses in engineering, psychology, military, and manufacturing. For example, a rocket launch status check involves a go/no-go test.

Uses

Engineering 
In engineering the test is traditionally used only to check noncritical parameters where the manufacturing process is believed to be stable and well controlled, and the tolerances are wide compared to the distribution of the parameter.

For example, the preceding launch status checks before a Space Shuttle liftoff had the flight controller perform a go/no-go check on each of the vehicle's critical systems.

Psychology 
In psychology, go/no-go test, developed by neuropsychologist Alexander Luria in 1940-50s is used to measure a participant's capacity for switching between several types of behavioural response ("plasticity") and control of adequacy of response (impulse control and sustained attention). Since the work of Alexander Luria in neuropsychology, such response is linked to the cortical frontal lobes.

For example, a go/no-go test that requires a participant to perform an action given certain stimuli (e.g., press a button) and also inhibit that action under a different set of stimuli (e.g., not press that same button).

Military 
In the United States Army, drills and proficiency evaluation rubrics are based on a go/no-go (pass/fail) system. Evaluations involving numerical scores (such as the physical fitness test) convert raw scores to go/no-go based on cutoffs defined by the particular performance standard for that area. Within a given skills unit, the rubric often specifies go/no-go scoring for each individual item or concept a soldier is expected to be trained and evaluated on. Usually, a soldier must score "go" (i.e. perform satisfactorily) on all sections of an evaluation in order to advance to the next phase of training, pass the course, or attain the particular qualification.

Manufacturing   

Go/no-go gauges are encountered in all types of manufacturing. 
They may measure a physical dimension, e.g. (50 ± 0.01 mm), or a value such as the value of a resistor (100 Ω (ohms) ± 1%).
A typical example is a plug gauge.

See also
Gauge block
Qualitative property
Shock detector
Litmus test (politics)
Evaluation of binary classifiers
Confusion matrix

References

External links 

 An online version of go/no-go test

Quality control
Simon Sze. Simon Min Sze, or Shi Min (; 21 March 1936 – 6 November 2023), was a Taiwanese-American electrical engineer. He is best known for inventing the floating-gate MOSFET with Korean electrical engineer Dawon Kahng in 1967.

Early life and education
Simon Min Sze was born in Nanjing, Jiangsu, and grew up in Taiwan. After graduating from the National Taiwan University in 1957, he received a master's degree from the University of Washington in 1960 and a doctorate from Stanford University in 1963.

Career and research
Sze worked for Bell Labs until 1990, after which he returned to Taiwan and joined the faculty of National Chiao Tung University.  He is well known for his work in semiconductor physics and technology, including his 1967 invention (with Dawon Kahng) of the floating-gate transistor, now widely used in non-volatile semiconductor memory devices.  He wrote and edited many books, including Physics of Semiconductor Devices, one of the most-cited texts in its field.

Death
Simon Sze died on 6 November 2023, at the age of 87.

Recognition
1977: IEEE Fellow
1991: J. J. Ebers Award<ref>[https://web.archive.org/web/20070228121715/http://www.ieee.org/portal/pages/society/eds/awards/ebers.html Electron Devices Society J.J. Ebers Award], web page at the IEEE, accessed 11-I-2007.</ref>
1994: Academician of Academia Sinica, Taiwan
1995: Member of National Academy of Engineering, United States
1998: Foreign Member of Chinese Academy of Engineering, China
2010: Tenured Chair Professor, National Chiao Tung University, Taiwan
2014: Honorary Chair Professor, National Taiwan University of Science and Technology, Taiwan
2017: IEEE Celebrated Member
2021: The Future Science Prize, China

Bibliography
 Physics of Semiconductor Devices, S. M. Sze. New York: Wiley, 1969, ; 2nd ed., 1981, ; 3rd ed., with Kwok K. Ng, 2006, .
 Nonvolatile Memories: Materials, Devices and Applications 2-volume set, Tseung-Yuen Tseng and Simon M. Sze.  Los Angeles: American Scientific Publishers, 2012; .
 Semiconductor Devices: Physics and Technology, S. M. Sze.  New York: Wiley, 1985; 2nd ed., 2001, ; 3rd ed., 2012, .
 VLSI Technology, ed. S. M. Sze. New York: McGraw-Hill, 1983, ; 2nd ed., 1988, .
 Modern Semiconductor Device Physics'', ed. S. M. Sze.  New York: John Wiley & Sons, Inc., 1998, .

References

1936 births
2023 deaths
American electrical engineers
American people of Taiwanese descent
National Taiwan University alumni
Scientists at Bell Labs
American people of Chinese descent
Members of the United States National Academy of Engineering
20th-century Chinese inventors
Engineers from Jiangsu
Taiwanese people from Jiangsu
Scientists from Nanjing
University of Washington alumni
Stanford University alumni
Academic staff of the National Chiao Tung University
Foreign members of the Chinese Academy of Engineering
Members of Academia Sinica
Fellows of the IEEE
Hexamethylphosphoramide. Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula  This colorless liquid is used as a solvent in organic synthesis.

Structure and reactivity
HMPA is the oxide of tris(dimethylamino)phosphine, P(NMe2)3. Like other phosphine oxides (such as triphenylphosphine oxide), the molecule has a tetrahedral core and a P=O bond that is highly polarized, with significant negative charge residing on the oxygen atom.

Compounds containing a nitrogen–phosphorus bond typically are degraded by hydrochloric acid to form a protonated amine and phosphate.

It dissolves alkali metal salts and alkali metals, forming blue solutions which are stable for a few hours. Solvated electrons are present in these blue solutions.

Applications
HMPA is a specialty solvent for polymers, gases, and organometallic compounds. It improves the selectivity of lithiation reactions by breaking up the oligomers of lithium bases such as butyllithium.  Because HMPA selectively solvates cations, it accelerates otherwise slow SN2 reactions by generating more bare anions. The basic nitrogen centers in HMPA coordinate strongly to Li+.

HMPA is a ligand in the useful reagents based on molybdenum peroxide complexes, for example, MoO(O2)2(HMPA)(H2O) is used as an oxidant in organic synthesis.

Alternative reagents
Dimethyl sulfoxide can often be used in place of HMPA as a cosolvent. Both are strong hydrogen bond acceptors, and their oxygen atoms bind metal cations. Other alternatives to HMPA include the N,N′-tetraalkylureas DMPU (dimethylpropyleneurea) or DMI (1,3-dimethyl-2-imidazolidinone). Tripyrrolidinophosphoric acid triamide (TPPA) has been reported to be a good substitute reagent for HMPA in reductions with samarium diiodide and as a Lewis base additive to many reactions involving samarium ketyls.

Toxicity
HMPA is only mildly toxic but has been shown to cause cancer in rats. HMPA can be degraded by the action of hydrochloric acid.

References

External links

Phosphoramides
Solvents
IARC Group 2B carcinogens
Staudinger reaction. The Staudinger reaction  is a chemical reaction of an organic azide with a phosphine or phosphite produces an iminophosphorane. The reaction was discovered by and named after Hermann Staudinger. The reaction follows this stoichiometry:
R3P + R'N3 → R3P=NR' + N2

Staudinger reduction
The Staudinger reduction is conducted in two steps. First phosphine imine-forming reaction is conducted involving treatment of the azide with the phosphine. The intermediate, e.g. triphenylphosphine phenylimide, is then subjected to hydrolysis to produce a phosphine oxide and an amine:
R3P=NR' + H2O → R3P=O + R'NH2

The overall conversion is a mild method of reducing an azide to an amine. Triphenylphosphine or tributylphosphine are most commonly used, yielding tributylphosphine oxide or triphenylphosphine oxide as a side product in addition to the desired amine. An example of a Staudinger reduction is the organic synthesis of the pinwheel compound 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene.

Reaction mechanism
The reaction mechanism centers around the formation of an iminophosphorane through nucleophilic addition of the aryl or alkyl phosphine at the terminal nitrogen atom of the organic azide and expulsion of diatomic nitrogen. The iminophosphorane is then hydrolyzed in the second step to the amine and a phosphine oxide byproduct.

Staudinger ligation
Of interest in chemical biology is the Staudinger ligation, which has been called one of the most important bioconjugation methods.  Two versions of the Staudinger ligation have been developed.  Both begin with the classic iminophosphorane reaction.  

In classical Staudinger ligation, the organophosphorus compound becomes incorporated into the peptide.   Typically, appended to the organophosphorus component are reporter groups such as fluorophores. In traceless Staudinger ligation, the organophosphorus group dissociates giving a phosphorus-free bioconjugate.

References

External links
Staudinger Reaction at organic-chemistry.org accessed 060906.
Julia-Staudinger Reaction

Organic redox reactions
Carbohydrate chemistry
Name reactions
Triethyl borate. Triethyl borate is a colorless liquid with the formula B(OCH2CH3)3. It is an ester of boric acid and ethanol.  It has few applications.

It is a weak Lewis acid (AN = 17 as measured by the Gutmann–Beckett method). It burns with a green flame and solutions of it in ethanol are therefore used in special effects and pyrotechnics.

It is formed by the reaction of boric acid and ethanol in the presence of acid catalyst, where it forms according to the equilibrium reaction:

B(OH)3 + 3 C2H5OH  (C2H5O)3B + 3 H2O

In order to increase the rate of forward reaction, the formed water must be removed from reaction media by either azeotropic distillation or adsorption. It is used as a solvent and/or catalyst in preparation of synthetic waxes, resins, paints, and varnishes. It is used as a component of some flame retardants in textile industry and of some welding fluxes.

References

External links
 National Pollutant Inventory - Boron and compounds
 WebBook page for BC6H15O3

Ethyl esters
Borate esters
Solvents
ROF Elstow. Royal Ordnance Factory (ROF) Elstow was one of sixteen UK Ministry of Supply, World War II, Filling Factories. It was a medium-sized filling factory, Filling Factory No. 16, which filled and packed munitions. It was located south of the town of Bedford, between the villages of Elstow and Wilstead in Bedfordshire. It was bounded on the northeast by the A6 and on the west by a railway line. Hostels were built nearby to  accommodate the workers who were mostly female.

It was built with the Ministry of Works acting as Agents; building work started in November 1940 and was completed by August 1941. It was managed as an "Agency Factory" by J. Lyons on behalf of the Ministry of Supply as, by then, the Ministry of Supply was overstretched as regards recruiting and managing the workers needed to staff these munitions factories.

It had 250 buildings and the site does not appear on Ordnance Survey maps made during wartime or in the postwar period.

Railway system 
There were 15 miles of standard gauge railway lines which were linked to the London, Midland and Scottish Railway (former Midland Railway) line running between London and Bedford. The junction was controlled from a signal box called Wilshamstead Junction. On the site a small platform called "Wilshamstead" was built to accommodate workmen's trains which ran from Bedford from 6 August 1941 (and Luton from 6 October 1941) until May 1946.

Wartime production 
ROF Elstow started filling munitions in February 1942.

It was divided into a number of different filling Groups (see Filling Factories) which occupied different areas of the site. The Groups filled cartridges, high-explosive (HE) and 4,000-pound bombs and shells. Later larger 8,000-pound, 12,000-pound and 22,000-pound bombs were also filled.

The Cordite Group opened in June 1942 and closed in May 1943; it was then employed to recondition shells. The Pellet Group also closed in 1943. After 1943 Elstow was used to store surplus ammunition components and machine tools.

Closure 
ROF Elstow closed in 1946. The CEGB took over the site in 1969 with the intention of building a power station but this never came to fruition.

In the early 1980s Elstow was proposed as a site for a UK nuclear waste repository. In 2007 work began on the new town of Wixams on the site. In the process of applying for planning permission for the Wixams development, a survey of the site was carried out which included interviews with former workers. The report, with site maps and annotated photographs, was published in 2009.

References

Further reading 
 Cocroft, Wayne D. (2000). Dangerous Energy: The archaeology of gunpowder and military explosives manufacture. Swindon: English Heritage.
 Bates, H. E. (1946). The Tinkers of Elstow: The Story of the Royal Ordnance Factory run by J. Lyons & Company Limited for the Ministry of Supply during the World War of 1939—1945. (Privately Published)
 Albion Archaeology Former Royal Ordnance Factory 16, Elstow, Bedfordshire, Building Recording and Oral History Project.

Economy of Bedfordshire
Filling factories
Royal Ordnance Factories in England