omniomni/omni-engineering huggingface dataset:
Zinc peroxide. Zinc peroxide (ZnO2) is a chemical compound of zinc that appears as a bright yellow powder at room temperature. It was historically used as a surgical antiseptic. More recently zinc peroxide has also been used as an oxidant in explosives and pyrotechnic mixtures. Its properties have been described as a transition between ionic and covalent peroxides.

Preparation and structure

Zinc peroxide can be synthesized through the reaction of zinc chloride and hydrogen peroxide.

According to X-ray crystallography, the compound consists of octahedral Zn(II) centers bonded to six distinct peroxide (O22-) ligands.  The overall motif is very similar to that for iron pyrite (FeS2).  The structure, with intact O-O bonds, makes clear that this material is a peroxide, not a dioxide.

Medical Use
The treatment of burrowing ulcers in the abdominal wall with zinc peroxide was first recorded in 1933 and throughout the 1940s ZnO2 was used as a disinfectant in surgical .
Zinc peroxide was, however, deemed ineffective against certain bacterial strains, such as Streptococcus viridans, staphylococcus aureus, E. coli, B. proteus, and B. pyocyoneus.

Safety
Zinc peroxide is hazardous in case of skin contact, of eye contact, or inhalation.

References

Peroxides
peroxide
Oxidizing agents
Web (manufacturing). A web is a long, thin, and flexible material. Common webs include foil, metal, paper, textile, plastic film, and wire. Common processes carried out on webs include coating, plating, and laminating.

A web is generally processed by moving over rollers.  Between processing stages, webs are stored and transported as rolls also known as coils, packages and doffs.  The end result or use of web manufacturing is usually sheets. The primary motivation to work with webs instead of sheets is economics. Webs, being continuous, can be made at far higher speeds and do not have the start-stop issues of discrete sheet processing. The size of the web-handling industries is unknown.

Related processes
Web processing 
Web processing is found in a wide variety of other manufacturing including electronics such as circuit boards, construction materials such as roofing, and pharmaceuticals such as drug patches. 

Web handling
Web handling refers to the processing of a web through a machine with maximum productivity and minimum waste.

See also
 Printed electronics
 Roll-to-roll processing
 Tape drives
 Web offset printing
 Roll slitting
 Calender
 Converters (industry)
 Cutting stock problem

References

Industrial processes
Fabrication (metal)
2005 in spaceflight. This article outlines notable events occurring in 2005 in spaceflight, including major launches and EVAs. 2005 saw Iran launch its first satellite.

Orbital launches

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Deep Space Rendezvous

EVAs

Orbital launch summary

By country

By rocket

By family

By type

By configuration

By launch site

By orbit

References

Footnotes

 
Spaceflight by year
Zirconium(II) hydride. Zirconium(II) hydride is a molecular chemical compound with the chemical formula . It is a grey crystalline solid or dark gray to black powder. It has been prepared by laser ablation and isolated at low temperature.

Zirconium(II) hydride has repeatedly been the subject of Dirac–Hartree–Fock relativistic calculation studies, which investigate the stabilities, geometries, and relative energies of hydrides of the formula , , , or MH.

Zirconium(II) hydride has a dihedral (C2v) structure. In zirconium(II) hydride, the formal oxidation states of zirconium and hydrogen are +2 and −1, respectively, because the electronegativity of zirconium is lower than that of hydrogen. The stability of metal hydrides with the formula  (M = Ti, Zr, Hf) decreases from Ti to Hf.

Uses
Zirconium(II) hydride is used as a thermal neutron moderator in nuclear reactors and as a material for neutron reflectors in fast reactors.

Zirconium(II) hydride in the form of a powder is used in powder metallurgy as a hydrogenation catalyst, vacuum tube getter, foaming agent in the production of metal foams and as a reducing agent.

References

See also
 Zirconium hydride

Metal hydrides
Zirconium(II) compounds
Zirconium(IV) silicate. Zirconium silicate, also zirconium orthosilicate, ZrSiO4, is a chemical compound, a silicate of zirconium. It occurs in nature as zircon, a silicate mineral. Powdered zirconium silicate is also known as zircon flour.

Zirconium silicate is usually colorless, but impurities induce various colorations. It is insoluble in water, acids, alkali and aqua regia. Hardness is 7.5 on the Mohs scale.

Structure and bonding
Zircon consists of 8-coordinated Zr4+ centers linked to tetrahedral orthosilicate SiO44- sites.  The oxygen atoms are all triply bridging, each with the environment OZr2Si.  Given its highly crosslinked structure, the material is hard, and hence prized as gemstone and abrasive.

Zr(IV) is a d0 ion.  Consequently the material is colorless and diamagnetic.

Production
Zirconium silicate occurs in nature as mineral zircon. Concentrated sources of zircon are rare.  It is mined from sand deposits and separated by gravity.  Some sands contain a few percent of zircon.

It can also be synthesized by fusion of SiO2 and ZrO2 in an arc furnace, or by reacting a zirconium salt with sodium silicate in an aqueous solution.

Uses
As of 1995, the annual consumption of zirconium silicate  was nearly 1M tons.  The major applications exploit its refractory nature and resistance to corrosion by alkali materials. Two end-uses are for enamels, and ceramic glazes. In enamels and glazes it serves as an opacifier. It can be also present in some cements.

Another use of zirconium silicate is as beads for milling and grinding.

Thin films of zirconium silicate and hafnium silicate produced by chemical vapor deposition, most often MOCVD, can be used as a high-k dielectric as a replacement for silicon dioxide in semiconductors.

Zirconium silicates have also been studied for potential use in medical applications. For example, ZS-9 is a zirconium silicate that was designed specifically to trap potassium ions over other ions throughout the gastrointestinal tract.

Zirconium silicate is also used as foundry sands due to its high thermal stability. t is also the primary source of zirconium, which is used in various applications, including in nuclear reactors, due to its high resistance to corrosion and low neutron absorption.

Toxicity
Zirconium silicate is an abrasive irritant for skin and eyes. Chronic exposure to dust can cause pulmonary granulomas, skin inflammation, and skin granuloma. However, there are no known adverse effects for normal, incidental ingestion.

References

Silicates
Zirconium(IV) compounds
Refractory materials
High-κ dielectrics
Fleet Defender. Fleet Defender is a combat flight simulator published by MicroProse in 1994. The game uses the F-14B version of the F-14 Tomcat even where anachronistic because the developers found the original, underpowered F-14A unforgiving and "not much fun" in an entertainment flight simulator. An expansion pack, Fleet Defender: Scenario, and a port for the PC-98 were released in 1995.

Tommo purchased the rights to this game and digitally published it through its Retroism brand in 2015.

Gameplay
Fleet Defender models detailed carrier operations including air traffic and take-off/landing under various conditions. The player has control of both the pilot and radar intercept officer (RIO) who manages the AWG-9 radar. Emphasis is placed on using the AIM-54 Phoenix missile as a standoff weapon where possible, rather than engaging the more nimble Soviet fighters in close-quarters dogfighting. Wingmen formations and support aircraft can also be controlled; unlike previous MicroProse simulations, as Computer Gaming World reported in 1994, "No longer do you alone, armed with a single aircraft and eight missiles, engage the entire third world".

Three campaign theaters are included in the original game: The Oceana training theater, the North Cape theater, and the Mediterranean theater (Italy, the Balkans, and part of North Africa).

Reception

Computer Gaming World in June 1994 said that "Fleet Defender pushes the envelope of desktop computers" but "strikes a very good balance between game play and pure graphic orgasm". Describing the game as a "tactical flight simulator" unlike a "close-in dog fighter like Falcon 3", it liked the accurate flight envelope, "extensive wingman controls", and "very good" enemy AI. The magazine concluded that "Fleet Defender is an outstanding simulator that will serve to reestablish MicroProse as a major player in the flight sim wars".

References

External links

Player's Guide

1994 video games
Combat flight simulators
DOS games
Linux games
MicroProse games
NEC PC-9801 games
Single-player video games
Tommo games
Video games developed in the United States
Windows games
3-Methylheptane. 3-Methylheptane is a branched alkane isomeric to octane. Its structural formula is CH3CH2CH(CH3)CH2CH2CH2CH3. It has one stereocenter.

Its refractive index is 1.398 (20 °C, D).

References

External links
Non-stereospecific oxidation of DL-3-methylheptane by aPseudomonas

Alkanes
Katarina Elevator. The Katarina Elevator or Katarina Lift () is a passenger elevator in Stockholm that connects Slussen (the sluice/lock area) to the heights of Södermalm. The lift was a shortcut between Katarinavägen, Slussen and Mosebacke torg. The original lift was constructed in 1881, but the current structure dates from the rebuilding of the Slussen transport interchange in 1936. The lift was closed for a lengthy renovation in 2010 and reopened in October 2023.

The old lift 
In 1881 the engineer Knut Lindmark, was permitted to build a lift and a bridge between Stadsgården and Mosebacke Torg (), to make it easier for people to move between the different heights of Södermalm. The lift was opened March the 19th 1883. During the first month approximately 1,500 passengers rode the lift daily. The price was 5 öre for going up and 3 öre for going down on the lift at that time.

The lift and bridge was constructed by the Belgian firm Lecoq & Comp, using a mechanism sourced from the American firm Weeks & Halsey. The original steam engine was replaced in 1915 with an electric engine.

The elevator is shown in a scene from the movie The Prize starring Paul Newman.

Gallery

Today, as of the reopening of the elevator 2023

References

External links

See also
Polanco Lift
Santa Justa Lift

Individual elevators
Buildings and structures in Stockholm
1883 establishments in Sweden
Transport in Stockholm
Transport infrastructure completed in 1883
Zinc cyanide. Zinc cyanide is the inorganic compound with the formula Zn(CN)2. It is a white solid that is used mainly for electroplating zinc but also has more specialized applications for the synthesis of organic compounds.

Structure
In Zn(CN)2, zinc adopts the tetrahedral coordination environment, all linked by bridging cyanide ligands. The structure consists of two "interpenetrating" structures (blue and red in the picture above).  Such motifs are sometimes called "expanded  diamondoid" structures. Some forms of SiO2 adopt a similar structure, wherein the tetrahedral Si centres are linked by oxides. The cyanide group shows head to tail disorder with any zinc atom having between one and four carbon neighbours, and the remaining being nitrogen atoms. It shows one of the largest negative coefficients of thermal expansion (exceeding the previous record holder, zirconium tungstate).

Chemical properties
Typical for an inorganic polymer, Zn(CN)2 is insoluble in most solvents. The solid dissolves in, or more precisely, is degraded by, aqueous solutions of basic ligands such as hydroxide, ammonia, and additional cyanide to give anionic complexes.

Synthesis
Zn(CN)2 is easy to make by combining aqueous solutions of cyanide and zinc ions, for example via the double replacement reaction between KCN and ZnSO4:
 ZnSO4 + 2 KCN → Zn(CN)2 + K2SO4

For commercial applications, some effort is made to avoid halide impurities by using acetate salts of zinc:
 Zn(CH3COO)2 + HCN → Zn(CN)2 + 2 CH3COOH

Zinc cyanide is also produced as a byproduct of certain gold extraction methods. Procedures to isolate gold from aqueous gold cyanide sometimes call for the addition of zinc:
 2 [Au(CN)2]−  +  Zn   →   2 Au  +  Zn(CN)2  +  2 CN−

Applications

Electroplating
The main application of Zn(CN)2 is for electroplating of zinc from aqueous solutions containing additional cyanide.

Organic synthesis
Zn(CN)2 is used to introduce the formyl group in to aromatic compounds in the Gatterman reaction where it serves a convenient, safer, and non-gaseous alternative to HCN. Because the reaction uses HCl, Zn(CN)2 also supplies the reaction in situ with ZnCl2, a Lewis acid catalyst. Examples of Zn(CN)2 being used in this way include the synthesis of 2-hydroxy-1-naphthaldehyde and mesitaldehyde.

Zn(CN)2 is also employed as a catalyst for the cyanosilylation of aldehydes and ketones.

References

zinc
cyanide
EMD F69PHAC. The EMD F69PHAC was an experimental locomotive built in 1989 in a joint venture between EMD and Siemens. It was designed to test AC locomotive technology. Only two examples of this locomotive were made. The engine used the same carbody as the EMD F40PHM-2, with just a few spotting differences.

They were built for the United States Department of Transportation and loaned to Amtrak in 1990, sporting Phase III paint. They were returned to EMD and later used with the German ICE train demonstration that was on loan to Amtrak in 1992–1993. They were repainted in ICE paint. The two F69PHAC locomotives were again returned to EMD, where they were finally retired in 1999. Both of the locomotives still exist in a scrap yard, more specifically National Railway Equipment, in Mount Vernon, Illinois, stripped of numerous parts.

References

External links 
 Photograph in Amtrak Phase III paint

F69PHAC-based passenger diesels
Experimental locomotives
Diesel locomotives of the United States
Railway locomotives introduced in 1988
B-B locomotives
Amtrak locomotives
Standard gauge locomotives of the United States
Coordinated flight. In aviation, coordinated flight of an aircraft is flight without sideslip.  

When an aircraft is flying with zero sideslip a turn and bank indicator installed on the aircraft's instrument panel usually shows the ball in the center of the spirit level. The occupants perceive no lateral acceleration of the aircraft and their weight to be acting straight downward into their seats. 

Particular care to maintain coordinated flight is required by the pilot when entering and leaving turns.

Advantages
Coordinated flight is usually preferred over uncoordinated flight for the following reasons:
it is more comfortable for the occupants
it minimises the drag force on the aircraft
it causes fuel to be drawn equally from tanks in both wings
it minimises the risk of entering a spin

Instrumentation
Airplanes and helicopters are usually equipped with a turn and bank indicator to provide their pilots with a continuous display of the lateral balance of their aircraft so the pilots can ensure coordinated flight.

Glider pilots attach a piece of coloured string to the outside of the canopy to sense the sideslip angle and assist in maintaining coordinated flight.

Axes of rotation

An airplane has three axes of rotation:  
Pitch – in which the nose of the airplane moves up or down. This is typically controlled by the elevator at the rear of the airplane.
Yaw – in which the nose of the airplane moves left or right. This is typically controlled by the rudder at the rear of the airplane.
Roll (bank) – in which one wing of the airplane moves up and the other moves down. This is typically controlled by ailerons on the wings of the airplane.

Coordinated flight requires the pilot to use pitch, roll and yaw control simultaneously. See also flight dynamics.

Coordinating the turn
If the pilot were to use only the rudder to initiate a turn in the air, the airplane would tend to "skid" to the outside of the turn. 

If the pilot were to use only the ailerons to initiate a turn in the air, the airplane would tend to "slip" toward the lower wing.

If the pilot were to fail to use the elevator to increase the angle of attack throughout the turn, the airplane would also tend to "slip" toward the lower wing.

However, if the pilot makes appropriate use of the rudder, ailerons and elevator to enter and leave the turn such that sideslip and lateral acceleration are zero the airplane will be in coordinated flight.

See also
 Adverse yaw

References
 Clancy, L.J. (1975), Aerodynamics, Pitman Publishing Limited, London 
 Coordinated flight Retrieved on 2008-09-19

Aerodynamics
Crystal monochromator. A crystal monochromator is a device in neutron and X-ray optics to select a defined wavelength of the radiation for further purpose on a dedicated instrument or beamline. It operates through the diffraction process according to Bragg's law. 

Similar devices are called crystal analyzer for the examination of scattered radiation.

Crystal Monochromator 
A crystal monochromator is an optical device used in X-ray and neutron spectroscopy to isolate a specific wavelength or a narrow range of wavelengths from a broader spectrum of radiation. It operates based on the principle of diffraction through a crystalline structure, governed by Bragg's Law. Crystal monochromators are integral to applications in materials science, structural biology, and high-energy physics.

Principles of Operation 
Crystal monochromators utilize the atomic lattice structure of a crystal to diffract incident radiation at specific angles. The diffraction condition is defined by Bragg’s Law:
nλ=2dsinθ
Where:

 n: Order of diffraction,
 λ: Wavelength of the incident radiation,
 d: Spacing between atomic planes in the crystal,
 θ: Angle of incidence.

By adjusting the angle of the crystal, the monochromator selectively allows radiation of a desired wavelength to pass while filtering out others.

Materials 
Commonly used materials for crystal monochromators include:

 Silicon (Si): Offers high purity and stability, ideal for synchrotron radiation.
 Germanium (Ge): Suitable for specific wavelength ranges due to its lattice properties.
 Quartz: Used for its thermal stability in certain applications.

These materials are chosen for their well-defined crystal lattice structures and their ability to withstand the operational environment.

Configurations 
Crystal monochromators can be designed in various configurations:

 Flat Crystal Monochromators: Use a single, flat crystal to diffract radiation. They are simple and commonly employed in laboratory X-ray setups.
 Double-Crystal Monochromators: Consist of two crystals aligned to improve wavelength purity and minimize beam divergence.
 Bent Crystal Monochromators: Use curved crystals to focus the diffracted beam, enhancing intensity and resolution.

Applications 
Crystal monochromators are widely used in scientific and industrial research:

 X-ray Diffraction (XRD): To study the atomic and molecular structure of materials.
 Synchrotron Beamlines: For producing monochromatic X-rays in synchrotron radiation facilities.
 Neutron Scattering: To isolate specific neutron wavelengths for scattering experiments.
 Spectroscopy: In high-resolution X-ray and neutron spectrometers to filter out unwanted wavelengths.

References

Neutron instrumentation
X-ray instrumentation
Synchrotron instrumentation
Potassium sulfide. Potassium sulfide is an inorganic compound with the formula K2S.  The colourless solid is rarely encountered, because it reacts readily with water, a reaction that affords potassium hydrosulfide (KSH) and potassium hydroxide (KOH). Most commonly, the term potassium sulfide refers loosely to this mixture, not the anhydrous solid.

Structure
It adopts "antifluorite structure," which means that the small K+ ions occupy the tetrahedral (F−) sites in fluorite, and the larger S2− centers occupy the eight-coordinate sites.  Li2S, Na2S, and Rb2S crystallize similarly.

Synthesis and reactions
It can be produced by heating K2SO4 with carbon (coke):
K2SO4  +  4 C  →  K2S  +  4 CO
In the laboratory, pure K2S may be prepared by the reaction of potassium and sulfur in anhydrous ammonia. 

Sulfide is highly basic, consequently K2S completely and irreversibly hydrolyzes in water according to the following equation:
K2S  +  H2O  →  KOH  +  KSH

For many purposes, this reaction is inconsequential since the mixture of SH− and OH− behaves as a source of S2−.  Other alkali metal sulfides behave similarly.

Use in fireworks
Potassium sulfides are formed when black powder is burned and are important intermediates in many pyrotechnic effects, such as senko hanabi and some glitter formulations.

See also
 Liver of sulfur

References

Potassium compounds
Sulfides
Inorganic compounds
Fluorite crystal structure
Dr. Grip. Dr. Grip (Dokutā Gurippu in Japan) is a brand of mechanical pencil made by Pilot Pens based in Japan. The Dr. Grip style also comes in a pen variety. It is well known for its "deflection-deflection/knock system." For its ergonomic features, the Dr. Grip pencil has been awarded the Arthritis Foundation's "Commendation for Ease-of-Use."

Features
The deflection-deflection system is a special form of lead advancement.  A pencil using this system is also commonly known as a "shaker pencil".  A small, metal weight lies around the core of the pencil, and when shaken, slides up and down; thus pushing the lead advancer down and advancing more lead.

For ergonomics, the Dr. Grip pencil was designed with a wide barrel and cushioned grip to relieve writing stress and fatigue.

Models
The majority of Dr. Grip pencil models only differ in color. The "Center of Gravity" pencil is a slightly different model in that it's designed with a different weight distribution for more comfortable, balanced writing. It also has a wide double layer comfort grip to reduce writing stress. In the United States this pencil comes in a model using 0.7mm lead only.  There is no knock system for the US model. In Japan the G-Spec Dr. Grip is available, which is the same pencil, but using 0.5mm lead with a knock system.

The pencils are available in 0.5mm and 0.7mm depending on the style of pencil.

List of Dr. Grip styles
Dr. Grip
LTD (US only) 0.5mm
GEL
Neon
G-Spec (Japan only) 0.5mm
Center of Gravity (US version of G-Spec, without knock system) 0.7mm
OffRoader 0.5mm
G-Spec white (Japan only) 0.5mm
4+1 (Japan only)
Putimo [mini] (Japan only) 0.5mm
Putimo Color [mini] (Japan only)
Mini
Sky-time 0.5mm
Aroma (Japan only) 0.5mm
Barazoku (Japan only)
PlayBorder (Asia only) 0.5mm
Frost Color Series (Japan only) 0.5mm
FullBlack (Japan only) 0.5mm
PureWhite (Japan only) 0.5mm

References

Pencil brands
Eric Traut. Eric Traut is an American software engineer and software emulation pioneer.  Traut graduated from Stanford University in 1992.  From 1993 to 1995 he worked for Apple Computer, creating a Mac 68K emulator to be used in PowerPC-based Macintoshes.  His work on this project led to a patent on a form of dynamic recompilation.

Traut went on to join Connectix, where he developed successful commercial emulators such as Virtual PC and Virtual Game Station.  He became Connectix's Chief Technical Officer in 2001.

Traut became a Microsoft employee after the company purchased Connectix in 2003.  Traut left Microsoft in late 2012. Traut rejoined Microsoft in May 2014 and is now a Technical Fellow.

References

External links
Eric Traut on Microsoft PressPass
Eric Traut talks about Windows 7 and MinWin

Living people
Microsoft employees
Microsoft technical fellows
American software engineers
Year of birth missing (living people)