omniomni/omni-engineering huggingface dataset:
Comparison of IRC clients. The following tables compare general and technical information between a number of notable IRC client programs which have been discussed in independent, reliable prior published sources.

General 
Basic general information about the notableclients: creator/company, license, etc. Clients listed on a light purple background are no longer in active development.

Release
A brief overview of the release history.

Operating system support
The operating systems on which the clients can run natively (without emulation).

Unix and Unix-like operating systems:
 Unix (BSD): 386BSD, BSD/OS, FreeBSD, NetBSD, OpenBSD, SunOS, ULTRIX
 Unix (System V): AIX, A/UX, HP-UX, IRIX, SCO OpenServer, Solaris, UnixWare
 Unix-like: Linux, NeXTSTEP, OpenVMS, OSF/1, QNX, Tru64 UNIX

Protocol support 
What IRC related protocols and standards are supported by each client.

Direct Client-to-Client (DCC) support 
The Direct Client-to-Client Protocol (DCC) has been the primary method of establishing connections directly between IRC clients for a long time now. Once established, DCC connections bypass the IRC network and servers, allowing for all sorts of data to be transferred between clients including files and direct chat sessions.

IRCv3 support 
This software is compliant natively; other software may be compliant with extensions.

IRCv3 SASL mechanisms 
IRC SASL authentication primarily uses the same mechanisms as SASL in other protocols. Most commonly:
 PLAIN as defined by RFC 4616
 EXTERNAL as defined by RFC 4422
 SCRAM-SHA-256 as defined by RFC 7677

Features 
Information on what features each of the clients support.

See also 
 Comparison of cross-platform instant messaging clients
 Comparison of user features of messaging platforms
 Comparison of instant messaging protocols
 Comparison of VoIP software
 List of SIP software
 Comparison of LAN messengers

References 

 
Internet Relay Chat clients
Mellite. Mellite, also called honeystone, is an unusual mineral being also an organic chemical. It is chemically identified as an aluminium salt of mellitic acid, and specifically as aluminium benzenehexacarboxylate hexadecahydrate, with the chemical formula Al2C6(COO)6·16H2O.

It is a translucent honey-coloured crystal which can be polished and faceted to form striking gemstones. It crystallizes in the tetragonal system and occurs both in good crystals and as formless masses. It is soft with a Mohs hardness of 2 to 2.5 and has a low specific gravity of 1.6.

It was discovered originally in 1789 at Artern in Thuringia, Germany. It has subsequently also been found in Russia, Austria, the Czech Republic, and Hungary. It was named from the Greek  meli "honey", in allusion to its color.

It is found associated with lignite and is assumed to be formed from plant material with aluminium derived from clay.

Structure
The crystal structure of mellite has been determined by neutron diffraction and consists of slightly distorted Al(H2O)63+ octahedra linked by hydrogen bonds to [C6(COO)6]6− mellitate anions and water of crystallization.

See also  
 Mellitic anhydride

References

Aluminium minerals
Organic minerals
Tetragonal minerals
Minerals in space group 142
Luminescent minerals
Minerals described in 1789
Hot box. A hot box is the term used when an axle bearing overheats on a piece of railway rolling stock.  The term is derived from the journal-bearing trucks used before the mid-20th century.  The axle bearings were housed in a box that used oil-soaked rags or cotton (collectively called "packing") to reduce the friction of the axle against the truck frame.  When the oil leaked or dried out, the bearings overheated, often starting a fire that could destroy the entire railroad car (and cars coupled to it) if not detected early enough.

The packing and bearing had to be regularly inspected by yard crews, and packing was often added at major stops. The journal bearing was replaceable, but if neglected, it would heat to a temperature where the babbitt bearing alloy would melt away, leaving the brass carrier riding on the steel axle, and result in a "taper journal".  This would eventually lead to the axle fracturing and the car above falling onto the wheel, or failure of the taper journal, causing the side frame and journal box to fall below the level of the rails, either of which could cause a major derailment of the train. Train worker duties consisted partly of inspecting the train as it ran by, looking for smoke, sparks, or fire. They would then sound the audible report "All Black" to mean the train was not giving off any light energy that would indicate combustion or destruction of the wheel bearings. If the train worker saw "Red" or smoke, he would alert other crew members, or else make an emergency stop to the train to prevent further damage.

When this type of axle box was used, any diesel exhaust smells had to be tracked to their source, as a hot-box sometimes smells similar. Most of the larger railroads use defect detectors to scan passing trains for hot box conditions. Some of these detectors also have "automated mile posts" which send an automated radio signal to the train crew listing the train number, track number, number of axles on the train and train speed.

Modern ball, roller or tapered bearings can also overheat, but the likelihood of a roller bearing overheating is usually far smaller than with journal bearings. When modern bearings do fail, the balls or rollers and their races fail, generating heat which can ignite fires or be the ignition source of a dust explosion in grain, coal, sawdust, etc.

Gallery

See also 
 Defect detector
 1833 Hightstown rail accident (United States)
 1943 Frankford Junction train wreck (United States)
 1979 Mississauga train derailment (Canada)
 1984 Summit tunnel fire (England)
  2023 Ohio train derailment (United States)

References

Bibliography 
 Railway Age magazine April 1, 1957
 Model Railroader 1980 May 62pp

Rolling stock
RRKM theory. The Rice–Ramsperger–Kassel–Marcus (RRKM) theory is a theory of chemical reactivity.  It was developed by Rice and Ramsperger in 1927 and Kassel in 1928 (RRK theory) and generalized (into the RRKM theory) in 1952 by Marcus who took the transition state theory developed by Eyring in 1935 into account.  These methods enable the computation of simple estimates of the unimolecular reaction rates from a few characteristics of the potential energy surface.

Assumption 
Assume that the molecule consists of harmonic oscillators, which are connected and can exchange energy with each other.
 Assume the possible excitation energy of the molecule to be , which enables  the reaction to occur.
 The rate of intra-molecular energy distribution is much faster than that of reaction itself.
 As a corollary to the above, the potential energy surface does not have any "bottlenecks" for which certain vibrational modes may be trapped for longer than the average time of the reaction

Derivation 
Assume that  is an excited molecule:

 

where  stands for product, and  for the critical atomic configuration with the maximum energy  along the reaction coordinate.

The unimolecular rate constant  is obtained as follows:

where  is the microcanonical transition state theory rate constant,  is the sum of states for the active degrees of freedom in the transition state,  is the quantum number of angular momentum,  is the collision frequency between  molecule and bath molecules,  and  are the molecular vibrational and external rotational partition functions.

See also
Transition state theory

References

External links
 An RRKM online calculator

Chemical physics
Quantum chemistry
Molecular physics
Chemical kinetics
Acryloyl chloride. Acryloyl chloride, also known as 2-propenoyl chloride, acrylyl chloride, or acrylic acid chloride, is the organic compound with the formula CH2=CHCO(Cl). It is a colorless liquid, although aged samples appear yellow. It belongs to the acid chlorides group of compounds.

Preparation
Acryloyl chloride can be efficiently prepared by treating acrylic acid with benzoyl chloride:  

Conventional phosphorus-based chlorinating agents, e.g. phosphorus trichloride, are ineffective.  Flow conditions allows use of a broadened range of chlorinating agents including oxalyl chloride and thionyl chloride.

Reactions
This compound undergoes the reactions common for acid chlorides.  For example, it reacts readily with water, producing acrylic acid.  When treated with sodium salts of carboxylic acids, the anhydride is formed. Reactions with alcohols and amines gives esters and amides, respectively.  It acylates organozinc compounds.

Acryloyl chloride is most commonly employed for the introduction of acrylic groups into other compounds, e.g. the preparation of acrylate monomers and polymers.

Toxicity
Acryloyl chloride, like volatile acid chlorides, is a skin irritant, with pulmonary edema in more severe exposures. Other signs and symptoms of acute exposure may include headache, dizziness, and weakness. Gastrointestinal effects may include nausea, vomiting, diarrhea, and stomach ulceration.

References

See also
 Methacryloyl chloride
 List of extremely hazardous substances
Acyl chlorides
Monomers
Lachrymatory agents
Vinyl compounds
DGN. DGN (design) is the name used for CAD file formats supported by Bentley Systems, MicroStation and Intergraph's Interactive Graphics Design System (IGDS) CAD programs. The DGN format is used in construction projects, including buildings, highways, bridges, process plants, shipbuilding. DGN is a competing format to  Autodesk's DWG.

Versions
There are two versions of DGN:

Intergraph Standard File Formats (ISFF) specification, published in the late 1980s by Intergraph. This is sometimes referred to as V7 DGN, or Intergraph DGN.
In 2000, Bentley Systems created an updated version of DGN which includes a superset of DGN's capabilities, but which has a different internal data structure to the ISFF-based DGN.  This version is properly referred to as V8 DGN.

History
In 2003 OpenDWG™ Alliance (now Open Design Alliance), a non-profit industry consortium committed to promoting open industry-standard formats for the exchange of CAD data, and Bentley Systems, Incorporated, announced that the Alliance will support V8 DGN. Bentley increased its membership level to become the Alliance's first supporting member. The Open Design Alliance provides Teigha for  files (old name is DGNdirect) - a development platform available using C++ that is used with  files and other graphics files.

In 2008 Autodesk and Bentley agreed on exchange of software libraries, including Autodesk RealDWG, to improve the ability to read and write the companies' respective DWG and DGN formats in mixed environments with greater fidelity. In addition, the two companies were to facilitate work process interoperability between their AEC applications through supporting the reciprocal use of available application programming interfaces (APIs).

References

External links
OpenDGN - Bentley's OpenDGN initiative
Teigha - a software development platform used to create engineering applications including CAD with native support of .dwg and .dgn files.
Microstation 95/ISFF Description (pdf) - Information on the ISFF/DGN file format as distributed with Microstation 95.
ISFF Specification - Intergraph Standard File Formats (Element Structure)

CAD file formats
Cantilever spar cable-stayed bridge. A cantilever spar cable-stayed bridge is a modern variation of the cable-stayed bridge. This design has been pioneered by the structural engineer Santiago Calatrava in 1992 with the Puente del Alamillo in Seville, Spain. In two of his designs the force distribution does not depend solely upon the cantilever action of the spar (pylon); the angle of the spar away from the bridge and the weight distribution in the spar serve to reduce the overturning forces applied to the footing of the spar. In contrast, in  his swinging Puente de la Mujer design (2002), the spar reaches toward the cable supported deck and is counterbalanced by a structural tail.  In the Assut de l'Or Bridge (2008), the curved backward pylon is back-stayed to concrete counterweights.

Of this type by Santiago Calatrava
Puente del Alamillo, Seville, Spain, 1992 (backward cantilever)
Trinity Bridge, Manchester, United Kingdom, 1995 (backward cantilever)
Puente de la Mujer, Buenos Aires, Argentina, 2002 (forward cantilever with gate-swing opening)
Sundial Bridge at Turtle Bay, Redding CA, USA, 2004 (backward cantilever with glass decking)
Chords Bridge, Jerusalem, Israel, opened 2008, light rail operative since 2011 (single-sided angled cantilever side-spar)
Assut de l'Or Bridge, Valencia, Spain, opened 12 December 2008 (backward curved pylon, back-stayed cantilever)
Samuel Beckett Bridge, Dublin, Ireland, opened 10 December 2009 (single-sided forward curved back-stayed pylon, evoking a harp)
Ponte di San Francesco da Paola, Cosenza, Italy, opened 26 January 2018 (backward pylon)
Signature Bridge, New Delhi, India, opened 4 November 2018 (Asymmetrical cable stayed pylon bridge)

Others of this type
Puente Atirantado (sometimes called Puente de la Unidad or Viaducto de la Unidad), opened in 2003, is a cable-stayed bridge that crosses the Río Santa Catarina and joins San Pedro Garza García with Monterrey. Although impressive and elegant, its construction was highly controversial due to its cost, its design (very similar to the one by Santiago Calatrava), and the fact that the river it crosses is dry.
Mariánský most – in Ústí nad Labem, Czech Republic. (1998)
Erasmusbrug – by Ben van Berkel, in Rotterdam Netherlands. 
Signature Bridge, Delhi, India, opened 5 November 2018.(Unique design of cables in a combinations of radial and semi-harp arrangement)

See also
Bridge – A directory of bridge types
Cable-stayed bridge – The ancestor of this type
Side-spar cable-stayed bridge – A related type

References

Bridges by structural type
Don Cuco El Guapo. "Don Cuco El Guapo" is a pianist robot designed and built at the department of microelectronics of the Universidad Autónoma de Puebla (UAP), Mexico in 1992.

The exterior of the robot was designed by sculptor Gloria Erika Weimer and is made of a crystal clear plastic, its body is 1.97 m tall (6'5") and weighs 130 kg (290 lb). The robot has 28 degrees of freedom and was provided cameras for eyes. Don Cuco is capable of reading musical scores and play the music on a piano. To perform such tasks the robot required the application of frame grabbing, image processing, pattern recognition and interpretation or analysis of scene. The design team of 30 faculty 20 students at UAP consisted of physicists, physicians, electronic engineers, computer scientists, musicians and designers who worked 20 hours daily for six months to complete the project.

The brains of the robot are based on the ILA 9200 microprocessor design in 1985 by scientists and engineers of Argentina, Brazil, Colombia, Spain and Mexico. The arithmetic logic unit (ALU) was designed at the department of microelectronics of the UAP.

The robot has been presented and has performed in Mexico, Spain and Latin America before millions of people.

External links
Official site  at the Universidad Autónoma de Puebla. 
Abstract of Musical Score Recognition of "Don Cuco El Guapo" Pianist Robot.

Cuco
Cuco
Robots of Mexico
1992 robots
Humanoid robots
Individual robots
European Network for Training and Research in Electrical Engineering. Exchange programs for Electrical Engineering students between 18 universities in Europe. It is also known as Entree. Their members are:
 Chalmers Lindholmen University College (Sweden)
 University of Aalborg (Denmark) 
 Heriot-Watt University (United Kingdom) 
 Brunel University (United Kingdom) 
 Delft University of Technology (Netherlands) 
 Université libre de Bruxelles (Belgium) 
 Technische Universität Dresden (Germany) 
 Karlsruhe Institute of Technology (Germany) 
 École Supérieure d'Ingénieurs en Électronique et Électrotechnique Paris (France) 
 École Supérieure d'Ingénieurs en Électronique et Électrotechnique Amiens (France) 
 École polytechnique fédérale de Lausanne (Switzerland) 
 Brno University of Technology (Czech Republic) 
 National Technical University of Athens (Greece) 
 Politecnico di Milano (Italy) 
 Pontifical Comillas University of Madrid (Spain) 
 University of Valladolid (Spain) 
 Institut Méditerranéen de Technologie (France) 
 Politecnico di Torino (Italy)

References 

College and university associations and consortia in Europe
Electrical engineering organizations
Engineering university associations and consortia
Barbier reaction. The Barbier reaction is an organometallic reaction between an alkyl halide (chloride, bromide, iodide), a carbonyl group and a metal. The reaction can be performed using magnesium, aluminium, zinc, indium, tin, samarium, barium or their salts. The reaction product is a primary, secondary or tertiary alcohol. The reaction is similar to the Grignard reaction but the crucial difference is that the organometallic species in the Barbier reaction is generated in situ, whereas a Grignard reagent is prepared separately before addition of the carbonyl compound. Unlike many Grignard reagents, the organometallic species generated in a Barbier reaction are unstable and thus cannot be stored or sold commercially. Barbier reactions are nucleophilic addition reactions that involve relatively inexpensive, water insensitive metals (e.g zinc powder) or metal compounds. For this reason, it is possible in many cases to run the reaction in water, making the procedure part of green chemistry. In contrast, Grignard reagents and organolithium reagents are highly moisture sensitive and must be used under an inert atmosphere without the presence of water. The Barbier reaction is named after Philippe Barbier, who was Victor Grignard's teacher.

Scope
Examples of Barbier reactions are the reaction of propargylic bromide with butanal with zinc metal (The attached reference details that the reaction goes to completion after the addition of saturated aqueous ammonium chloride):

the intramolecular Barbier reaction with samarium(II) iodide:

the reaction of an allyl bromide with formaldehyde in THF with indium powder:

The reaction of 3-Bromocyclohexene with benzaldehyde and zinc powder in water:

Asymmetric variants

The synthesis of (+)-aspicillin, starts first with a hydroboration, then transmetallation to zinc which can then do an addition into the aldehyde substituent.

See also 
Nozaki–Hiyama–Kishi reaction
Indium mediated allylation

External links 
 Barbier reaction @ University of Connecticut Website

References 

Addition reactions
Free radical reactions
Carbon-carbon bond forming reactions
Name reactions
Molecules (journal). Molecules is a peer-reviewed open access scientific journal that focuses on all aspects of chemistry and materials science. It was established in March 1996 and is published monthly by MDPI. From 1997 to 2001, Molbank was published as a section of the journal, before splitting into its own journal. The editor-in-chief is Farid Chemat.

Molecules was initially published by Springer-Verlag. In December 1996, Shu-Kun Lin resigned as editor and relaunched the journal with Molecular Diversity Preservation International (MDPI). Springer initially sued over naming rights, but eventually dropped the suit.

Abstracting and indexing
The journal is abstracted and indexed in:

According to the Journal Citation Reports, the journal has a 2023 impact factor of 4.2.

References

External links 

 

Chemistry journals
Creative Commons Attribution-licensed journals
Academic journals established in 1996
MDPI academic journals
Monthly journals
English-language journals
Stepping stones. Stepping stones or stepstones are sets of stones arranged to form an improvised causeway that allows a pedestrian to cross a natural watercourse such as a creek, a small river; or a water feature in a garden where water is allowed to flow between stone steps. Unlike bridges, stepstone crossings typically have no spans, although wood planks or stone slabs can be placed over between the stones (which serve as the piers) to improvise as low-water bridges. Although their historical origin is unknown, stepping stones, along with log bridges, are likely to have been among the earliest means of crossing inland bodies of water devised by humans.

In traditional Japanese gardens, the term iso-watari refers to stepping stone pathways that lead across shallow parts of a pond, which work like a bridge-like slower crossing. Using iso-watari for crossing ponds, or shallow parts of streams, one can view the aquatic animals and plants around or in the pond, like carp, turtles, and waterfowl.

Today, stepping stones are commonly used by mountaineers and hikers as a makeshift way of crossing uncharted or unanticipated streams and torrents. They may occur alongside a ford.

Historic stepping stones

The Drukken Steps in the Eglinton Woods of North Ayrshire in Scotland were a favourite haunt of poet Robert Burns and his companion Richard Brown, while the two were living in Irvine from 1781 to 1782.

The name "Drukken" steps derives from a person's gait as they stepped from stone to stone whilst crossing the Red Burn. Seven or more stones were originally set in the Red Burn which was much wider than in 2009.

Burns himself used the Scots spelling "Drucken" rather than "Drukken". The ruins of the Drukken Steps are in the Eglinton Country Park.

In popular culture 
A deadly version of stepping stones involving glass tiles is featured in the 2021 South Korean series Squid Game as the fifth game played in the series.

See also 
 Clapper bridge
 Footbridge
 Ford (crossing)
 Kulgrinda

References

External links

Stepping stones on the River Ayr
Stepping stones on the Annick Water

Footbridges
Stone bridges
Garden features
Stonemasonry
Chinese gardening styles
Japanese style of gardening
River crossings