omniomni/omni-engineering huggingface dataset:
Ammonium paratungstate. Ammonium paratungstate (or APT) is a white crystalline salt with the chemical formula (NH4)10(H2W12O42)·4H2O.  It is described as "the most important raw material for all
other tungsten products."

Production

From tungsten ores
Tungsten ores, which are typically oxides, are digested in base to give solutions of tungstate together with many contaminating species.  This crude extract is acidified and treated with sulfide to separate molybdenum trisulfide.  Upon further acidification APT eventually crystallizes.

Laboratory methods
If a calcined WO3 is used, refluxing the ammonia solution is advisable to accelerate its dissolution.

Conversion to tungsten metal
Heating ammonium paratungstate to its decomposition temperature of 600 °C yields tungsten(VI) oxide, as described in this idealized equation:
(NH4)10(H2W12O42)·4H2O  →  12 WO3  +  10 NH3  + 6 H2O

From there, the trioxide is heated in an atmosphere of hydrogen, yielding elemental tungsten:
WO3  +  3 H2  →  W + 3 H2O

Structure

The anion in (NH4)10(W12O41)·5H2O has been shown to be [H2W12O42]10−, containing two hydrogen atoms, keeping two hydrogen atoms inside the cage. The correct formula notation for ammonium paratungstate is therefore (NH4)10[H2W12O42]·4H2O. The [H2W12O42]10− ion is known as the paratungstate B ion, as opposed to the paratungstate A ion, that has the formula [W7O24]6−, similar to the paramolybdate ion. The existence of the paratungstate A ion, could not be confirmed by NMR spectroscopy, however.

Before about 1930, there has been some dispute about the exact composition of the salt, and both (NH4)10W12O41 and (NH4)6W7O24 were proposed. O.W. Gibbs remarked about this: 
"The alkali tungstates are numerous and unusually complex. Salts of essentially different formulae approach so closely in percentage composition, that the differences lie very near the unavoidable errors of analyses. The analyses are hardly sufficiently close to decide the question upon purely analytical grounds."

Other hydrates
When concentrating an ammoniacal solution of tungstic acid (i.e. hydrous WO3), the product obtained is ammonium paratungstate. Below 50 °C, the hexahydrate is formed, whereas when the temperature of the solution is above 50 °C, the pentahydrate or heptahydrate is formed. The former crystallizes as triclinic plates or prisms, whereas the latter as pseudorhombic needles. The tetrahydrate is most significant in a commercial sense.  Also known:
decahydrate
nonahydrate

References 

Ammonium compounds
Tungstates
Gigli saw. A Gigli saw is a flexible wire saw used by surgeons for bone cutting. A Gigli saw is used mainly for amputation, where the bones have to be smoothly cut at the level of amputation. It is also used in veterinary medicine for cutting antler, horn, and tusks, as well as bone.

The saw was invented by Leonardo Gigli, an Italian obstetrician, to simplify the performance of a lateral pubiotomy in obstructed labour.

It is featured in the 2023 American horror film Saw X.

See also
Instruments used in general surgery

References

Orthopaedic instruments
Saws
Italian inventions
Land disposal unit. A land disposal unit, or LDU, is a site in which hazardous waste is remedied through natural and man-made processes.
"Land disposal" of hazardous waste is defined in the U.S. Resource Conservation and Recovery Act (RCRA). Types of LDUs for hazardous waste disposal:
 Landfill
 Surface impoundment
 Waste pile
 Land treatment unit
 Injection well
 Salt dome formation
 Salt bed formation
 Mine
 Cave.

References

 Land disposal unit
Waste legislation in the United States
Waste treatment technology
Land treatment unit. A land treatment unit (LTU) is a location in which land is treated, usually through bioremediation processes, to reduce the toxicity of the soil.

Land treatment units are areas where hazardous waste is applied or incorporated into the soil surface. Land treatment units are typically units consisting of natural soils where natural biological and chemical degradation and attenuation processes immobilize, transform, or degrade hazardous constituents over time.

LTUs are becoming more common as more sites requiring clean-up are identified.

See also
 Land disposal unit

Notes

Waste treatment technology
Bradbury–Nielsen shutter. A Bradbury–Nielsen shutter (or Bradbury–Nielsen gate) is a type of electrical ion gate, which was first proposed in an article by Norris Bradbury and Russel A. Nielsen, where they used it as an electron filter. Today they are used in the field of mass spectrometry where they are used in both TOF mass spectrometers and in ion mobility spectrometers 
, as well as Hadamard transform mass spectrometers (a variant of TOF-MS). The Bradbury–Nielsen shutter is ideal for injecting short pulses of ions and can be used to improve the mass resolution of TOF instruments by reducing the initial pulse size as compared to other methods of ion injection.

Theory of operation
The concept behind the Bradbury–Nielsen shutter is to apply a high frequency voltage in a 180° out-of-phase manner to alternate wires in a grid which is orthogonal to the path of the ion beam. This results in charged particles only passing directly through the shutter at certain times in the voltage phase (φ=nπ/2), when the potential difference between the grid wires is zero. At other times the ion beam is deflected to some angle by the potential difference between the neighboring wires. This deflection is divergent with ions that pass through alternate slits being deflected in opposite directions.  The maximum deflection angle  can be calculated by

tan α = k Vp / V0

where α is the deflection angle, k is a deflection constant, Vp is the wire voltage (+Vp on one wire set and -Vp on the other), and V0 is the ion acceleration voltage in eV.  The deflection constant k can be calculated by

k = π / 2ln[cot(πR/2d)]

where R is the wire radius and d is the wire spacing.

Micromachined ion gates
A Bradbury-Nielsen Gate micromachined from a silicon on insulator wafer has been reported.

References

See also
Ion mobility spectrometer
Time-of-flight

Mass spectrometry
Takeuchi Manufacturing. is a Japanese heavy construction machinery company that manufactures excavators, track loaders, crawler dumpers and wheel loaders.

History 
Takeuchi was founded in 1963 by Akio Takeuchi as a construction equipment manufacturer. Takeuchi developed the world's first compact excavator in 1971 and in 1986 he introduced the compact track loader, another world first. 

The company has wholly owned subsidiary facilities in the United States (1979), United Kingdom (1996), France (2000) and China (2006).

Gallery

References

External links 

  

Construction equipment manufacturers of Japan
Companies based in Nagano Prefecture
Companies listed on the Tokyo Stock Exchange
Manufacturing companies established in 1963
Japanese brands
Japanese companies established in 1963
Rubb hall. A Rubb Hall is a commercial name for particularly large, relocatable tent-like structure often used in situations of emergency (e.g. humanitarian) and temporary industry (e.g. construction projects).  The name derives from Rubb Building Systems, and Hall Engineering of Bergen Norway, manufacturers of this kind of structure. Other types of similar structure include HAGUHALL.

Rubb Halls are usually made of aluminium frames, with steel tension wires and polyester skins. They typically come in sections so the length can be determined by the number of sections employed. A common standard size is an area of 200 square metres. Doors at either end are made from the same material as the walls, and are drawn back like curtains. More secure and longer lasting structures include Flospan - frameless steel structures.

Various specialised modifications are possible, including the fitting of artificial ceilings inside, together with doors in end walls, to facilitate heating. It is also not unheard of to have a frame erected inside to provide a second floor.

In humanitarian aid situations, Rubb Halls are often used as warehouses for items such as food and medicine. They are also used for temporary emergency shelter for large numbers of people, and as spaces for activities such as person registration to take place under shelter.

See also
 Nissen hut

References

Portable buildings and shelters
Lattice girder. A lattice girder is a truss girder where the load is carried by a web of  latticed metal.

Overview
The lattice girder was used prior to the development of larger rolled steel plates. It has been supplanted in modern construction with welded or bolted plate girders, which use more material but have lower fabrication and maintenance costs. 

The term is also sometimes used to refer to a laced strut or laced tie, structural members commonly made using a combination of structural sections connected with diagonal lacing. This form allows a strut to resist axial compression and a  (tie) to resist axial tension. A lattice girder, like any girder, primarily resists bending.

The component sections may typically include metal beams, channel and angle sections, with the lacing elements either metal plate strips, or angle sections. The lacing elements are typically attached using either hot rivets or threaded locator bolts. As with lattice girders, laced struts and ties have generally been supplanted by hollow box sections, which are more economic to produce with modern technology. In some case seismic retrofit modifications replace riveted lacing with plates bolted in place.

Examples of  lattice girders
Manhattan Bridge
Runcorn Railway Bridge
Kew Railway Bridge
Dowery Dell Viaduct
Bennerley Viaduct
Cayey Bridge
Dalguise Viaduct
Viaduc d'Ormaiztegi

Examples of laced struts or ties
The Eiffel Tower.
The obsolescent eastern span of the San Francisco–Oakland Bay Bridge. The western span has been retrofitted with bolted plates replacing the lacing for added strength. The eastern span has been replaced.
The internal structure of the Statue of Liberty.
The sides of the Cape Fear Memorial Bridge.
Certain viaducts of the Chicago "L" system.

See also
Hares Hill Road Bridge
Lattice truss bridge – an extension of the concept to form a deep truss

References

Girders
Trusses
 Girder
Mitsubishi PX33. The Mitsubishi PX33 is a prototype passenger car built by Mitsubishi Heavy Industries, the company which would eventually sire Mitsubishi Motors. Commissioned for military use by the Japanese government in 1934, it was the first Japanese-built sedan to have full-time four-wheel drive, a technology the company would return to fifty years later in pursuit of motorsport success. Four working prototypes were built, and a version was in development using Mitsubishi's 6.7 litre,  445AD powerplant, Japan's first direct injection diesel engine. However, the entire PX33 project was cancelled in 1937 after the government decided to prioritize Mitsubishi's manufacturing capabilities on commercial development of trucks and buses. In 1937, another Japanese company Tokyu Kurogane Kogyo began production of a smaller four-wheel drive car called the Kurogane Type 95.

The PX33 received renewed attention as a marketing tool for Mitsubishi during the release of the fourth generation Mitsubishi Pajero. The PX33's historical and technological link to the company's newest sport utility vehicle saw both cars displayed in parallel at the Paris Motor Show in September 2006.

References

PX33
All-wheel-drive vehicles
Cars introduced in 1934
Tetrarhodium dodecacarbonyl. Tetrarhodium dodecacarbonyl is the chemical compound with the formula Rh4(CO)12.  This dark-red crystalline solid is the smallest binary rhodium carbonyl that can be handled as a solid under ambient conditions.  It is used as a catalyst in organic synthesis.

Structure, synthesis, reactions
According to X-ray crystallography,  features a tetrahedral array of four Rh atoms with nine terminal CO ligands and three bridging CO ligands.  The structure can be expressed as Rh4(CO)9(μ-CO)3.

  is prepared by treatment of an aqueous solution of  rhodium trichloride with activated copper metal under an atmosphere of CO.

4 RhCl3(H2O)3   +   8 Cu   +   22 CO   →       +   2 CO2   +   8 Cu(CO)Cl   +   4 HCl   +   10 H2O

Alternatively, the compound can be prepared by treatment of a methanolic solution of RhCl3(H2O)3 with CO to afford H[RhCl2(CO)2], followed by carbonylation in the presence of sodium citrate.

The cluster undergoes thermal substitution with phosphine ligands, L:
Rh4(CO)12   +   n L   →   Rh4(CO)12-nLn   +   n CO

Tetrarhodium dodecacarbonyl quantitatively decomposes in boiling hexane to afford hexadecacarbonylhexarhodium:

Related metal carbonyls
Because of their relevance to hydroformylation catalysis, rhodium carbonyls have been systematically studied to a high degree. The instability of Rh2(CO)8 has been a source of curiosity.  The analogous binary carbonyl of cobalt, Co2(CO)8, is well known.  Solutions of Rh4(CO)12 under high pressures of CO convert to the dirhodium compound:

 + 4 CO → 

Unlike Co2(CO)8 which features bridging carbonyls, the main isomer of Rh2(CO)8 features only terminal CO ligands.  The relative instability of Rh2(CO)8 is analogous to the tendency of Ru(CO)5 to convert to Ru3(CO)12.

References

General reading
 King, R. B., "Rhodium: Organometallic Chemistry" Encyclopedia of Inorganic Chemistry 1994, 7, 3494.

Organorhodium compounds
Carbonyl complexes
Chemical compounds containing metal–metal bonds
Rhodium(0) compounds
Frederick Grinnell. Frederick Grinnell (August 14, 1836 – October 21, 1905) was a pioneer in fire safety and was the creator of the first practical automatic fire sprinkler.

Early life and education
He was born in New Bedford, Massachusetts. In 1855, he graduated from Rensselaer Polytechnic Institute.

Career
Earlier in his career, he was draftsman, construction engineer, and manager for various railroad manufacturers. He designed and oversaw construction of more than 100 locomotives. In 1869, he purchased a controlling interest in a company that manufactured fire-extinguishing apparatus. Grinnell licensed a sprinkler device patented by Henry S. Parmalee, then worked to improve the invention, and in 1881 patented the automatic sprinkler that bears his name. He continued to improve the device and in 1890 invented the glass disc sprinkler, essentially the same as that in use today. Such sprinklers are called le Grinnell in France. He secured some 40 distinct patents for improvements on his sprinklers, and invented a dry pipe valve and the automatic fire-alarm system as well.

General Fire Extinguisher Co.
In 1892, Grinnell organized the General Fire Extinguisher Co. in Providence, R.I., an amalgamation of several smaller companies, which became the foremost organization in its field of manufacture. Grinnell died in 1905 in his hometown of New Bedford. In 1919, General Fire Extinguisher Co. was renamed Grinnell Co. In 1969, Grinnell Co. was purchased by ITT (International Telephone & Telegraph) and became ITT Grinnell. A few years later, ITT Grinnell sold its US industrial activities to Tyco International. Grinnell remains today a trade mark inside the Tyco group. In 2001, Grinnell Fire Protection was merged with the Simplex Time Recorder Company to form SimplexGrinnell, which is the largest fire protection company in the world. ITT Grinnell supporting products are still sold today by Anvil International in the US and PSS in Germany.

Grinnell was a director of several banks and manufacturing companies.  He was inducted into the Rhode Island Heritage Hall of Fame in 1984.

References

1836 births
1905 deaths
American engineers
Rensselaer Polytechnic Institute alumni
Graphic Adventure Creator. Graphic Adventure Creator (often shortened to GAC) is a game creation system/programming language for adventure games published by Incentive Software, originally written on the Amstrad CPC by Sean Ellis, and then ported to other platforms by, amongst others, Brendan Kelly (Spectrum), Dave Kirby (BBC, Electron) and "The Kid" (Malcolm Hellon) (C64). The pictures in the demo adventure, Ransom, were made by Pete James and the box cover art by Pete Carter.

GAC was released in 1985 for the Amstrad CPC and in 1986 for the ZX Spectrum, Commodore 64 and BBC Micro. A simplified version without graphics, called just the Adventure Creator, was also released for the Acorn Electron in 1987. GAC was ported to the Atari ST in 1988 as ST Adventure Creator (STAC) by the original author.

GAC had a more advanced parser than The Quill, allowing commands like GET THE LAMP THEN LIGHT IT, and a built-in graphics editor. Over 300 titles were written using GAC. It also came with a built in text compressor.

Reception 
GAC was well received, earning a Zzap! Gold Medal Award and a Crash Smash. Your Sinclair reviewed the ZX Spectrum version giving it a 9/10 score. The ST version reached number 18 on the bestsellers chart in August 1988.

See also
 The Quill, another common text adventure engine

References

External links

1985 software
Interactive fiction engines
Graphic Adventure Creator, The
ZX Spectrum software
BBC Micro and Acorn Electron software
Cyclopentadienylmolybdenum tricarbonyl dimer. Cyclopentadienylmolybdenum tricarbonyl dimer is the chemical compound with the formula Cp2Mo2(CO)6, where Cp is C5H5.  A dark red solid, it has been the subject of much research although it has no known practical uses.

Structure and synthesis
The molecule exists in two rotamers, gauche and anti. The six CO ligands are terminal and the Mo-Mo bond distance is 3.2325 Å. The compound is prepared by treatment of molybdenum hexacarbonyl with sodium cyclopentadienide followed by oxidation of the resulting NaMo(CO)3(C5H5). Other methods have been developed starting with Mo(CO)3(CH3CN)3 instead of Mo(CO)6.

Reactions
Thermolysis of this compound in hot solution of diglyme (bis(2-methoxyethyl)ether) results in decarbonylation, giving the tetracarbonyl, which has a formal triple bond between the Mo centers (dMoMo = 2.448 Å):
(C5H5)2Mo2(CO)6  →  (C5H5)2Mo2(CO)4 +  2 CO
The resulting cyclopentadienylmolybdenum dicarbonyl dimer in turn binds a variety of substrates across the metal-metal triple bond.

Related compounds
 Cyclopentadienyltungsten tricarbonyl dimer
 Cyclopentadienylchromium tricarbonyl dimer

References

Organomolybdenum compounds
Carbonyl complexes
Dimers (chemistry)
Half sandwich compounds
Cyclopentadienyl complexes
Chemical compounds containing metal–metal bonds
Aluminium sulfate (data page). This page provides supplementary chemical data on aluminium sulfate.

Material Safety Data Sheet  

The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source and follow its directions.
ScienceLab.com

Structure and properties

Thermodynamic properties

Spectral data

References 

Chemical data pages
Chemical data pages cleanup
Cyclooctadiene rhodium chloride dimer. Cyclooctadiene rhodium chloride dimer is the organorhodium compound with the formula Rh2Cl2(C8H12)2, commonly abbreviated [RhCl(COD)]2 or Rh2Cl2(COD)2.  This yellow-orange, air-stable compound is a widely used precursor to homogeneous catalysts.

Preparation and reactions
The synthesis of [RhCl(COD)]2 involves heating a solution of hydrated rhodium trichloride with 1,5-cyclooctadiene in aqueous ethanol in the presence of sodium carbonate:
2 RhCl3·3H2O + 2 COD + 2 CH3CH2OH + 2 Na2CO3 → [RhCl(COD)]2 + 2 CH3CHO + 8 H2O + 2 CO2 + 4 NaCl

[RhCl(COD)]2 is principally used as a source of the electrophile "[Rh(COD)]+."
[RhCl(COD)]2 + L → [LRh(COD)]+Cl− (where L = PR3, alkene, etc. and  = 2 or 3)
In this way, chiral phosphines can be attached to Rh. The resulting chiral complexes are capable of asymmetric hydrogenation.  A related but still more reactive complex is chlorobis(cyclooctene)rhodium dimer. The dimer reacts with a variety of Lewis bases (L) to form adducts with the stoichiometry RhCl(L)(COD).

Structure
The molecule consists of a pair of square planar Rh centers bound to a 1,5-cyclooctadiene and two chloride ligands that are shared between the Rh centers. The Rh2Cl2 core is also approximately planar, in contrast to the highly bent structure of cyclooctadiene iridium chloride dimer where the dihedral angle is 86°.

References

External links

Organorhodium compounds
Homogeneous catalysis
Cyclooctadiene complexes
Dimers (chemistry)
Chloro complexes
Rhodium(I) compounds
Barium nitrate (data page). This page provides supplementary chemical data on barium nitrate.

Material Safety Data Sheet  

The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source  and follow its directions.
SIRI
MSDS from BARIUM AND CHEMICALS INC in the SDSdata.org database
Science Stuff

Structure and properties

Thermodynamic properties

Spectral data

References 

Chemical data pages
Chemical data pages cleanup
Standard (1911 automobile). The Standard was a German automobile manufactured between 1911 and 1912. The car was produced at Berlin-Charlottenburg using a rotary valve engine built by Henriod, which was unreliable and had not been fully developed; consequently, it was very unpopular.

References
 David Burgess-Wise, The New Illustrated Encyclopedia of Automobiles. .

Defunct motor vehicle manufacturers of Germany
Cars introduced in 1911
Rolamite. A Rolamite is a technology for very low friction bearings developed by Sandia National Laboratories in the 1960s. It consists of two cylindrical rollers held captive in a channel by an S-shaped metal strip. The strip is under tension, which keeps the rollers pressed together with the strip between them. The rollers move linearly within the channel as they counter-rotate. During the motion each contact surface has the same surface velocity, which results in very low friction. The Rolamite can be used in various ways such as a component in switches, thermostats, valves, pumps, and clutches.

Development
The Rolamite was invented by Sandia engineer Donald F. Wilkes and was patented on June 24, 1969. It was invented while Wilkes was working on a miniature device to detect small changes in the inertia of a small mass. After testing an S-shaped metal foil, which he found to be unstable to support surfaces, the engineer inserted rollers into the S-shaped bends of the band, producing a mechanical assembly that has very low friction in one direction and high stiffness transversely. It became known as Rolamite.

The Rolamite uses a stressed metal band and counter-rotating rollers within an enclosure to create a linear bearing device that loses very little energy to friction. An article in Popular Mechanics claims it is the only basic mechanical invention of the 20th century. Tests by Sandia indicated that Rolamite mechanisms demonstrated friction coefficients as low as 0.0005, an order of magnitude better than ball bearings at the time. There are known Rolamite versions that contain two bands that work in reciprocate parallel for more accurate kinematic transmission at the reverse motion.

A video of a Rolamite in operation, to serve as a warhead safety-switch accelerometer, is available.

See also
Scrollerwheel

References

Linear

 
Bishop,James E., (11/27/1973). "Remember the Rolamite? World's 27th-and Newest-'Elementary Mechanism' Still Works, but It Hasn't Revolutionized Technology" The Wall Street Journal Page 46.

Rotary

External links 
Compilation of Rolamite information and articles Including pictures and applications.

Linear
 Video of a homemade rolamite

Rotary
U.S. Patent #5,462,363

Simple machines
Bearings (mechanical)