omniomni/omni-engineering huggingface dataset:
Quaternium-15. Quaternium-15 (systematic name: hexamethylenetetramine chloroallyl chloride) is a quaternary ammonium salt that has been used as a surfactant and preservative. It acts as an antimicrobial agent because it slowly releases formaldehyde, which is a preservative with biocidal properties.

Both quaternium-15 and formaldehyde release agents have been the subjects of controversy.  They are often banned in US and Europe. 

It can be found under a variety of names, including Dow Chemical Company: Dowicil 200 (cis isomer only), Dowicil 75 and Dowicil 100 (both a mix of cis and trans isomers).

Synthesis
Quaternium-15 can be prepared by treating hexamethylenetetramine with 1,3-dichloropropene.  A mixture of cis and trans isomers are produced.

Applications
The isolated cis-compound is used primarily in cosmetic applications, with a maximum permitted concentration in the EU of 0.2%. The mixed product (cis- and trans-) is used in a wider range of formulations such as: emulsifiable metal-cutting fluids, latex and emulsion paints, liquid floor polishes and floor waxes, and glues and adhesives.

Safety concerns 

Quaternium-15 has been banned in the EU since 2017 and a bill was introduced in the US in 2017 to require the FDA to investigate its safety.

Allergic reaction 
Quaternium-15 is an allergen, and can cause dermatitis. Many of those with an allergy to quaternium-15 are also allergic to formaldehyde. At low pHs, it would be expected to release significant amounts of formaldehyde due to acid hydrolysis via the Delepine reaction. Allergic sensitivity to quaternium-15 can be detected using a patch test.
It is the single most often found cause of allergic contact dermatitis of the hands (16.5% in 959 cases). In 2005–06, it was the fourth-most-prevalent allergen in patch tests (10.3%).

Although quaternium-15 releases low amounts of formaldehyde. Even so, Johnson & Johnson announced plans to phase out its use of quaternium-15 in cosmetic products by 2015 in response to consumer pressure.

See also 
 Polyquaternium

References

External links
 
 
 Occupational Hazards - Quaternium-15 

Cosmetics chemicals
Preservatives
Quaternary ammonium compounds
Reactive dye. In a reactive dye, a chromophore (an atom or group whose presence is responsible for the colour of a compound) contains a substituent that reacts with the substrate. Reactive dyes have good fastness properties owing to the covalent bonding that occurs during dyeing. Reactive dyeing is the most important method for coloring cellulose fibers. Reactive dyes can also be applied on wool and nylon; in the latter case they are applied under weakly acidic conditions. Reactive dyes have a low utilization degree compared to other types of dyestuff, since the functional group also bonds to water, creating hydrolysis.

Usage
Reactive dyes had been tested in the late 1800s involving both adding functionalized dyes to the substrate and then activating the substrate first followed by fixation of the dye. The first commercial success was described in the early 1950s.  Rattee and Stephens at Imperial Chemical Industries (ICI) popularized the chlorotriazines as linkers between the substrate and the chromophore.

Trichlorotriazine remain a popular platform for reactive dyes. The chromophore, with an amine functional group, is attached to the triazine, displacing one chloride:
 (NCCl)3 + dye-NH2 → N3C3Cl2(NHdye) + HCl
The resulting dichlorotriazine can then be affixed to the cellulose fibre by displacement of one of the two chloride groups:
 N3C3Cl2(NHdye) + HO-cellulose → N3C3Cl(NHdye)(O-cellulose) + HCl
The fixation process is conducted in a buffered alkaline dye bath.

An alternative fixation process that is more dominant commercially is the vinylsulfonyl group. Like the chlorotriazines, this functional group adds to the hydroxyl groups of cellulose. The most popular version of this technology is Remazol. The dye is first attached to the ethylsulfonyl group.

Reactive dyes are categorized by functional group.

Bi- and polyfunctional reactive dyes
Dyestuffs with only one functional group sometimes have a low degree of fixation. To overcome this deficiency, dyestuffs containing two (or more) different reactive groups were developed. These dyestuffs containing two groups are also known as bifunctional dyestuffs although some still refer to the original combination.  Some contain two monochlorotriazines, others have a combination of the triazines and one vinyl sulfone group).  Bifunctional dyes can be more tolerant to temperature deviations (better process). Other bifunctionals have been created, some with fastness (better quality) or only fixation degree (better environment or economy) in mind.

See also
 Carbene dye
 Cationization of cotton for salt-free dyeing
 Dyeing
 Dispersing agent for dyeing

Footnotes

External links
For more info Fundamental Chemistry of reactive dyes
Advancements in Reactive Textile Dyes

Dyes
Carbene dye. A carbene dye is a reactive dye based on carbene chemistry.

A benzophenone is functionalised with a chromophore or group that can be easily converted to a chromophore at a later stage. The functionalised benzophenone is reacted with hydrazine hydrate and subsequently treatment with mercury oxide. The resulting diazo compound is stable at room temperature. On heating, nitrogen gas is released and the carbene generated. 
The thus generated carbene reacts rapidly with substrates such as nylon, cotton, glass and polyethylene.

The highly reactive carbene group removes the need for different functional groups depending on the substrate to be dyed. For example, a dye that can colour cotton would usually not be appropriate for dyeing polyethylene, but by using a carbene, the same dye can be used for both.

References 
 
 "A Method for the Functionalisation of Polymeric Substrates", K. Awenat, W. Ebenezer, M.G. Moloney, GB9824023 D0 (1998-12-30); WO0026180 A1 (2000-05-11); EP1124791 A1 (2001-08-22); JP2002529542 T (2002-09-10); US6699527 B1 (2004-03-02)

Dyes
Carbenes
Gavin Fisher. Gavin Fisher (born 30 August 1964) is a British was formerly Chief Designer of the Williams Formula One team.

Career 
He studied mechanical engineering at University of Hertfordshire, which was famous for its aeronautical engineers, graduating with a first class honors degree. He was hired by Williams through an advertisement in the media in 1988 after spending time with Ricardo transmissions. A few months later, Adrian Newey joined Williams from Leyton House and Fisher worked with him until Newey left in 1997 to join McLaren. Fisher, his pupil, was promoted to the role of chief designer, a role that he held until 2005.

In September 2004, Gavin Fisher was seriously injured in a motorbike crash and underwent surgery for a broken pelvis in a hospital in Los Angeles. Senior designer Mark Loasby took over the design of next year's Williams race car during his absence.

Personal life 
Fisher currently follows a number of pursuits including snowboarding, riding motorbikes and sailing boats.

References

External links
Profile at grandprix.com

Alumni of the University of Hertfordshire
British mechanical engineers
Living people
1964 births
Formula One designers
British motorsport people
Williams Grand Prix Engineering
Soft lithography. In technology, soft lithography is a family of techniques for fabricating or replicating structures using "elastomeric stamps, molds, and conformable photomasks". It is called "soft" because it uses elastomeric materials, most notably PDMS.

Soft lithography is generally used to construct features measured on the micrometer to nanometer scale. According to Rogers and Nuzzo (2005), development of soft lithography expanded rapidly from 1995 to 2005.  Soft lithography tools are now commercially available.

Types 
 PDMS stamp
 Microcontact printing
 Multilayer soft lithography
 Nanosphere lithography
 Patterning by etching at the nanoscale

Advantages

Soft lithography has some unique advantages over other forms of lithography (such as photolithography and electron beam lithography). They include the following:
Lower cost than traditional photolithography in mass production
Well-suited for applications in biotechnology
Well-suited for applications in plastic electronics
Well-suited for applications involving large or nonplanar (nonflat) surfaces
More pattern-transferring methods than traditional lithography techniques (more "ink" options)
Does not need a photo-reactive surface to create a nanostructure
Smaller details than photolithography in laboratory settings (~30 nm vs ~100 nm). The resolution depends on the mask used and can reach 6 nm.

See also 
 Nanolithography

References

Further reading 
 
 
 
 

Lithography (microfabrication)
Bark hack. A bark hack is a tool used to remove pine tree bark to promote the flow of pine resin, which is used in naval stores production. The tool consists of a wooden shaft with a weighted butt and hook-like, replaceable, U-shaped blades at the head.  

The bark hack is swung much like an axe and is used to create a hatched chevron pattern ("cat face" or less frequently, a "blaze") into trees' exposed sapwood. The weighted end helps the operator follow through with the force necessary for the hooked blade to scoop out chips of hard pine wood.

External links
image

Woodworking hand tools
Forestry tools

The first sentence is basically correct except that the blade is straight rather than curved.  With the bark hack, only the bark is removed; it does not cut into the wood as the wood hack did.  The wood hack was used up until the early 1950s and the trees were "chipped or streaked" each week during the sap flow season.  With the bark hack, only the bark was removed and a 50% sulfuric acid solution was sprayed on the "streak" and it had to be done only every 2 weeks.
Hammermill. A hammer mill is a mill whose purpose is to shred or crush aggregate material into smaller pieces by the repeated blows of small hammers. These machines have numerous industrial applications, including:

 Ethanol plants (grains)
 A farm machine, which mills grain into coarse flour to be fed to livestock
 Fluff pulp defiberizing
 Fruit juice production
 Grinding used shipping pallets for mulch
 Milling grain
 Livestock, poultry, and aquatic feed production
 Sawmills, size reduction of trim scrap and planer shavings into boiler fuel or mulch

 Shredding paper
 Shredding scrap automobiles (see automotive shredder residue)
 Shredding yard and garden waste for composting
 Crushing large rocks
 In waste management

Operation
The basic principle is straightforward. A hammer mill is essentially a steel drum containing a vertical or horizontal rotating shaft or drum on which hammers are mounted. The hammers are free to swing on the ends of the cross, or fixed to the central rotor. The rotor is spun at a high speed inside the drum while material is fed into a feed hopper. The material is impacted by the hammer bars and is thereby shredded and expelled through screens in the drum of a selected size.

The hammermill can be used as a primary, secondary, or tertiary crusher.

Small grain hammermills can be operated on household current. Large hammer mills used in automobile shredders may be driven by diesel or electric motors ranging from 2000 to over 5000 horsepower (1.5 - 3.7MW).

The screenless hammer mill uses air flow to separate small particles from larger ones. It is designed to be more reliable, and is also claimed to be much cheaper and more energy efficient than regular hammermills.
The design & structure of the hammermill is always determined by the end use.

History
Water-powered trip hammer mills were created in 488 AD by the medieval Chinese mathematician and engineer Zu Chongzhi which was inspected by Emperor Wu of Southern Qi (r. 482–493 AD). The water-powered trip hammer mills were powered by minor hill flowing stream that was connected to a large river beneath the high banks.

Types of Hammer Mill Crushers
Types of Hammer Mill Crushers can include "up running" and "down running" hammer mills - 

 "Up Running" - Uses perforated screens or grate bars to reduce soft or hard materials. The material to be reduced determines the rotor construction that can be adjustable based on wear.
 "Down Running" - Most suitable for fibrous materials due to the high concentration of shearing action within the unit.
Based on the director of the motor the hammer mills are classified into the following types:

 Reversible hammer mill
 Non-reversible hammer mill

Although the mills are classified into the above two different types their working and grinding actions of both these types of mill are almost similar. However, their construction differs in various respects.

See also
 Blade grinder
 Trip hammer, which may be housed in a mill usually known as a forge, but which was historically occasionally described as a “hammermill.”

References 

hammer mills
Chinese inventions
Steve Chen (computer engineer). Steve Chen (; pinyin: Chén Shìqīng; born 1944) is a Taiwanese computer engineer and internet entrepreneur.

Chen was elected to the US National Academy of Engineering in 1991 for leadership in the development of super-computer architectures and their realization.

Education
Chen earned a Bachelor of Science from National Taiwan University in 1966, a Master of Science from Villanova University in 1971 and a Ph.D. under David Kuck from the University of Illinois at Urbana-Champaign in 1975.

Career 
From 1975 through 1978 he worked for Burroughs Corporation on the design of the Burroughs large systems line of supercomputers. He is best known as the principal designer of the Cray X-MP and Cray Y-MP multiprocessor supercomputers.  Chen left Cray Research in September 1987 after it dropped the MP line.

With IBM's financial support, Chen founded Supercomputer Systems Incorporated (SSI) in January 1988.
SSI was devoted to development of the SS-1 supercomputer, which was nearly completed before the estimated $150 million investment ran out. The Eau Claire, Wisconsin-based company went bankrupt in early 1993, leaving more than 300 employees jobless.

An attempt to salvage the work was made by forming a new company, SuperComputer International (SCI), later that year. SCI was renamed Chen Systems in 1995. It was acquired by Sequent Computer Systems the following year. John Markoff, a technology journalist, wrote in the New York Times that Chen was considered "one of the nation's most brilliant supercomputer designers while working in this country for the technology pioneer Seymour Cray in the 1980s."

In 1999, Chen became founder and CEO of Galactic Computing, a developer of supercomputing blade systems, based in Shenzhen, China.
At Tonbu, Inc., his team designed and implemented the world's first fully scalable cloud computing system. A fully scalable dynamic process and application engine. 
 
By 2005 he started to focus on grid computing to model a human brain instead.

By 2010, he was reported to be working on technology to use cloud computing to improve health care in rural China.

In 2011, he founded Information Supergrid Technologies USA.

See also 
Taiwanese Americans

References

External links
Galactic Computing

1944 births
Living people
American computer businesspeople
American people of Chinese descent
Cray employees
Businesspeople in information technology
Computer designers
People from Nanping
Supercomputing in China
Taiwanese emigrants to the United States
Grainger College of Engineering alumni
Villanova University alumni
Heat exchange. Heat exchange may refer to:

Heat transfer, an area of engineering concerned with the transfer of thermal energy (heat)
Heat exchanger, a device built for heat transfer from one medium to another
Air conditioner, a device that cools interior air, such as that of a building or vehicle
Heat sink, a device used to absorb energy, typically by using its large mass to raise its temperature slightly or by changing phase
Radiator, a device used to either move heat away from an object or heat an interior space by circulating a fluid through thin metal tubes
Refrigerator, a device used to cool objects or interior spaces
Space heater, a device used to heat spaces, typically interior spaces
DACS. DACS may refer to:

 Data & Analysis Center for Software, United States Department of Defense information analysis center
 De La Rue Automatic Cash System, early ATM
 Describing Archives: A Content Standard, standard for describing collections
 Design and Artists Copyright Society, UK copyright collecting society for visual art
 Digital access and cross-connect system, telecommunications equipment in the United States
 Digital Access Carrier System, telecommunications equipment in the United Kingdom
 Distributed Access Control System, single sign-on and role-based access control system
 Dax, Landes, a town in Nouvelle-Aquitaine, France, known in Occitan as Dacs

See also

 DAC (disambiguation)
 Daks (disambiguation)
 Dack (disambiguation)
B-36 Peacemaker Museum. The B-36 Peacemaker Museum is a non-profit organization "Dedicated to the preservation of the rich aviation history of North Texas".

Original purpose of the museum
The museum was originally created to preserve and display the last Convair B-36 built. Of 386 B-36s built from 1945 to 1954, only four intact examples survive. B-36-J-III 52-2827 City of Fort Worth was built in Fort Worth, Texas in 1954. The aircraft was accepted by the Air Force on August 14, 1954 and was retired on 12, February 1959. It was displayed at Amon Carter Field, later Greater Southwest International Airport, from 1959 until the late 1970s, when it was moved to Carswell Air Force Base. Exposed to the extremes of Texas weather, the giant aircraft slowly deteriorated. In the early 1990s the aircraft was disassembled and moved indoors to hangar space at the factory where it was built, donated by Lockheed Aircraft. A group of dedicated volunteers, many of them retired Convair employees who had worked on the original B-36 assembly line, spent 40,000 person-hours restoring the plane.

Transfer of the B-36 to Arizona
The aircraft is officially owned by the National Museum of the United States Air Force (NMUSAF), but was on loan to the B-36 Peacemaker Museum. In 2006, it was agreed that the Peacemaker Museum did not have the proper resources to restore and exhibit the aircraft, and the aircraft was trucked to the Pima Air & Space Museum (PASM) in Tucson, Arizona where it was restored and is currently exhibited. In the arid Tucson climate, it is possible to display aircraft outdoors without the kind of deterioration that occurred in Fort Worth. As the National Museum of the United States Air Force still retains ownership of the aircraft, the future direction of the B-36 Peacemaker Museum is still undecided.

External links
Museum website
B-36 City of Fort Worth page at Pima Air & Space Museum 
 
 

Aerospace museums in Texas
Museums in Fort Worth, Texas
Military and war museums in Texas
Museum
1819 in rail transport. 

Events

April events
 April 13 – The Mansfield and Pinxton Railway, a wagonway in the midlands of England, opens for coal traffic.

June events
 June 24 – James Foster and John Urpeth Rastrick partner to form Foster, Rastrick and Company, the English firm that will build the first steam locomotives for the Delaware and Hudson Railroad.

Births

February births 
 February 20 – Alfred Escher, Swiss railway promoter (d. 1882)

October births 
 October 27 – Henry B. Plant, president of the Plant System of railroads (d. 1899).

Deaths

April deaths 
 April 15 – Oliver Evans, pioneering American steam locomotive designer and inventor (b. 1755).

References

 Bedwell, Carolyn (2002), John Urpeth Rastrick. Retrieved April 4, 2005.
 Bedwell, Carolyn (2002), John Urpeth Rastrick – Chronology. Retrieved April 22, 2005 — date for Foster, Rastrick and Company formation.
 Senate House Library, University of London, John Bradley & Co (Stourbridge) Ltd., Ironfounders . Retrieved April 22, 2005 — info on Foster, Rastrick and Company, verifies Foster family connections.
Oxygen difluoride. Oxygen difluoride is a chemical compound with the formula . As predicted by VSEPR theory, the molecule adopts a bent molecular geometry. It is a strong oxidizer and has attracted attention in rocketry for this reason. With a boiling point of −144.75 °C, OF2 is the most volatile (isolable) triatomic compound. The compound is one of many known oxygen fluorides.

Preparation
Oxygen difluoride was first reported in 1929; it was obtained by the electrolysis of molten potassium fluoride and hydrofluoric acid containing small quantities of water. The modern preparation entails the reaction of fluorine with a dilute aqueous solution of sodium hydroxide, with sodium fluoride as a side-product:

Structure and bonding
It is a covalently bonded molecule with a bent molecular geometry and a F-O-F bond angle of 103 degrees. Its powerful oxidizing properties are suggested by the oxidation number of +2 for the oxygen atom instead of its normal −2.

Reactions
Above 200 °C,  decomposes to oxygen and fluorine by a radical mechanism.

 reacts with many metals to yield oxides and fluorides. Nonmetals also react: phosphorus reacts with  to form  and ; sulfur gives  and ; and unusually for a noble gas, xenon reacts (at elevated temperatures) yielding  and xenon oxyfluorides.

Oxygen difluoride reacts with water to form hydrofluoric acid:

It can oxidize sulphur dioxide to sulfur trioxide and elemental fluorine:

However, in the presence of UV radiation, the products are sulfuryl fluoride () and pyrosulfuryl fluoride ():

Safety

Oxygen difluoride is considered an unsafe gas due to its oxidizing properties. It reacts explosively with water. Hydrofluoric acid produced by the hydrolysis of  with water is highly corrosive and toxic, capable of causing necrosis, leaching calcium from the bones and causing cardiovascular damage, among a host of other highly toxic effects. Other acute poisoning effects include: pulmonary edema, bleeding lungs, headaches, etc. Chronic exposure to oxygen difluoride, like that of other chemicals that release fluoride ions, can lead to fluorosis and other symptoms of chronic fluoride poisoning. Oxygen difluoride may be associated with kidney damage. The maximum workplace exposure limit is 0.05 ppm.

Popular culture
In Robert L. Forward's science fiction novel Camelot 30K, oxygen difluoride was used as a biochemical solvent by fictional life forms living in the solar system's Kuiper belt. While  would be a solid at 30K, the fictional alien lifeforms were described as endothermic, maintaining elevated body temperatures and liquid  blood by radiothermal heating.

Notes

References

External links
 National Pollutant Inventory - Fluoride and compounds fact sheet
 WebBook page for 
 CDC - NIOSH Pocket Guide to Chemical Hazards

Oxygen fluorides
Rocket oxidizers
SUPER-UX. SUPER-UX was a version of the Unix operating system from NEC that is used on its SX series of supercomputers.

History
The initial version of SUPER-UX was based on UNIX System V version 3.1 with features from BSD 4.3. The version for the NEC SX-9 was based on SVR4.2MP with BSD enhancements.

Features
SUPER-UX is a 64-bit UNIX operating system. It supports the Supercomputer File System (SFS).

Earth Simulator
The Earth Simulator uses a custom OS called "ESOS" (Earth Simulator Operating System) based on SUPER-UX. It has many enhanced features custom designed for the Earth Simulator which are not in the regular SUPER-UX OS.

See also
 EWS-UX

References

External links
NEC Europe HPC
NEC Japan HPC
Official NEC SUPER-UX page, Archived 6 May 2008

UNIX System V
NEC supercomputers
Supercomputer operating systems