Lionel Ferbos

Lionel Charles Ferbos (July 17, 1911 – July 19, 2014) was an American jazz trumpeter. He was from New Orleans, Louisiana.
At 103, Ferbos was the oldest jazz musician in New Orleans. A native New Orleanian whose career centered almost exclusively in the city, he appeared weekly at the Palm Court Jazz Cafe, a French Quarter club, where he led the Palm Court Jazz Band on Saturday nights.
During his long career, Ferbos worked with some of the giants of early traditional jazz, including Captain John Handy and Mamie Smith, and, in later years, with widely recognized contemporary revivals of the old style music like the original stage band of the off-Broadway hit "One Mo' Time". He played at all of the New Orleans Jazz & Heritage Festivals.
Early life.
Lionel Ferbos was born on July 17, 1911, in New Orleans, in the city's Creole 7th Ward. He said he had asthma and his parents would not let him take up a wind instrument, but when he was 15 he saw Phil Spitalny's all-girl orchestra at the Orpheum and argued that he ought to be able to do anything a girl could do. So he got an old cornet at a pawn shop on Rampart Street and began lessons with Professor Paul Chaligny, an exacting Creole task-master who would not let him blow the horn until he knew how to read music and had mastered the rudiments of theory. After a year with Chaligny, Ferbos moved on to study with noted musicians Albert Snaer and Eugene Ware.
Early career.
Ferbos' first professional music jobs were in the early 1930s with society jazz bands like the Starlight Serenaders and the Moonlight Serenaders, performing at well-known New Orleans venues like the Pythian Roof Garden, Pelican Club, San Jacinto Hall, Autocrat Club, Southern Yacht Club and the New Orleans Country Club. In 1932, he joined Captain Handy's Louisiana Shakers and played the Astoria and toured the Gulf Coast. He later backed blues singer Mamie Smith while playing with the Fats Pichon Band. During the Depression, he worked as a laborer in New Orleans City Park for the Works Progress Administration, then played first trumpet in the WPA jazz band, of which he is the last surviving member. In the 1940s, he played on Lake Pontchartrain at the Happy Landing and Mama Lou's, and in the '50s he worked with Harold Dejan at the Melody Inn, where he recorded with the "Mighty Four." In the '60s he played with Herbert Leary's Orchestra.
Because of his ability to read sheet music, Ferbos found himself in demand. Although he wasn't a "hot player", as he described it, he said he never had to scramble for work because people came to him with musical offers. When Danny Barker founded the now-famous Fairview Baptist band to train a young generation of New Orleans musicians, Ferbos was asked to write out all their charts.
Later career.
Until he reached retirement age, Ferbos kept his day job, so his musical work was mostly in and around New Orleans. During his career he held a job at Haspel's Clothing Factory in the early 1930s. It was here that he met a seamstress, Marguerite Gilyot, who became his wife. She died in January 2009 after 75 years of marriage. In the 1940s, Ferbos went to work in his father's sheet-metal business and became a master metal worker. His artistry as a tinsmith was featured in the acclaimed exhibition on Creole building arts at the New Orleans Museum of Art. In the 1970s, he dropped out of the hit musical "One Mo' Time" when it moved to New York, rather than leave town. However, he made eight tours of Europe with the New Orleans Ragtime Orchestra, formed to revive the old music unearthed in the jazz archives at Tulane University. He was trumpeter with the Ragtime on the soundtrack of the 1978 movie "Pretty Baby".
Ferbos won the 2003 Big Easy Lifetime Achievement Award and was frequently called on to tell about his experiences in the Depression, as well as in music and with tinsmithing, on panels and in history classes. In 2005, Hurricane Katrina forced him to Plaquemines Parish, Louisiana, where he lived with relatives until he could return to his native New Orleans.
Despite his long career, Lionel Ferbos made few early recordings. After he joined the Ragtime and the Palm Court bands, he was recorded on several CDs on the GHB label. He was also featured on other recent recordings with New Orleans headliners on specialty labels.
Personal life.
Lionel Ferbos had a daughter, Sylvia Schexnayder, and was pre-deceased by wife Marguerite Gilyot Ferbos and son Lionel Ferbos Jr.
Ferbos died on the morning of July 19, 2014, at his home in New Orleans. He was 103 years old.


RL60

The RL60 was a planned liquid-fuel cryogenic rocket engine designed in the United States by Pratt & Whitney, burning cryogenic liquid hydrogen and liquid oxygen propellants. The engine runs on an expander cycle, running the turbopumps with waste heat absorbed from the main combustion process. This high-efficiency, waste heat based combustion cycle combined with the high-performance liquid hydrogen fuel enables the engine to reach a very high specific impulse of up to 465 seconds in a vacuum. The engine was planned to be a more capable successor to the Aerojet Rocketdyne RL10, providing improved performance and efficiency while maintaining the installation envelope of the RL10.
RL60 was planned to include major improvements to the high-thrust RL10B-2, such as up to 45 engine restarts (up from 15 for RL10B-2), 550 seconds longer engine lifetime (+15.7%), and twice the thrust. Like the RL10B-2, RL60 was planned to incorporate a radiatively cooled extendable nozzle. RL60 was designed to meet the evolving needs of expendable launch requirements and human-rated missions of the early 2000's.
Description.
RL60 is an expander cycle, liquid-fuel cryogenic rocket engine burning liquid hydrogen and liquid oxygen. The engine's cycle is virtually identical to the RL10, with some key changes:
Other key changes from the RL10 include:
While the RL60 is designed, integrated and tested in the US, the engine sources multiple components from international partners:
History.
The RL60 has its beginnings in the original commercial Cryogenic Advanced Upper Stage Engine (cCAUSE) program, which began in 1999 and resulted in the RL50 program, a planned 220 kN (50,000 lbf) thrust class engine. The RL50 program later evolved to develop a cryogenic engine that encompassed the requirements and capabilities of both the planned RL50 and ArianeGroup's Vinci engine, the European 180 kN thrust expander cycle LH2/LOX upper-stage engine. The intention was for the RL50 engine to function as the upper stage engine for both US and European expendable launch vehicles, achieving effective cost management and economies of scale through a common engine shared between the European Ariane 5 and future Atlas and Delta US vehicles. The planned collaboration between Snecma, the provider of RL10's carbon-carbon composite nozzles, and Pratt & Whitney effort resulted in the RL50 engine being designated the SPW2000 (Snecma-P&W; 2000 indicates the year).
However, the RL50 program was not fully embraced by ESA due to concerns about competition with European rocket engine manufacturers and problems in setting up a work-sharing agreement among the two companies and their subcontractors. The SPW2000 program was thus rejected by ESA, resulting in the SPW2000 program's cancellation on 22 June 2000. Pratt & Whitney re-established the project under its own RL60 program, so-called to identify it design thrust level of 60,000 lbf. The RL60 Demonstrator Program was initiated in the end of 2000, and was planned to enter full-scale development in early 2003.
In 2003, Pratt & Whitney Space Propulsion had 90% of the work completed for the RL60 engine. The RL60 was to be built and tested in the US, with key components provided by four international industry strategic suppliers: Volvo Aero of Sweden (regeneratively cooled nozzle); Ishikawajima-Harima Heavy Industries (IHI) of Japan (LH2 turbopump); Techspace Aero of Belgium (LH2 inlet and LOX control valves); and Chemical Automatics Design Bureau (CADB) of Russia (LOX turbopump). As well as performing the systems engineering and integration for the engine, Pratt & Whitney would have manufactured the thrust chamber assembly (TCA) of the engine, consisting of the injector assembly and ignition system, the control system and accompanying valves and plumbing, and the main combustion chamber.
In September 2003, the first combustion chamber for the engine was delivered to be tested. This testing resulted in an unknown (classified) anomaly. The root cause of the anomaly was identified and a second test was planned, but activities attempting to recover from the anomaly were slowed due to uncertain future market opportunities and timing.
The development testing of the engine was planned to culminate in the testing of the first full-scale engine in early 2005, followed by engine qualification and certification in 2006. RL60 production and delivery of flight engines to customers was planned to start in mid-2006.


Borane

Trihydridoboron, also known as borane or borine, is an unstable and highly reactive molecule with the chemical formula . The preparation of borane carbonyl, BH3(CO), played an important role in exploring the chemistry of boranes, as it indicated the likely existence of the borane molecule. However, the molecular species BH3 is a very strong Lewis acid. Consequently it is highly reactive and can only be observed directly as a continuously produced, transitory, product in a flow system or from the reaction of laser ablated atomic boron with hydrogen.
Structure and properties.
BH3 is a trigonal planar molecule with D3h symmetry. The experimentally determined B–H bond length is 119 pm.
In the absence of other chemical species, it reacts with itself to form diborane. Thus, it is an intermediate in the preparation of diborane according to the reaction:
The standard enthalpy of dimerization of BH3 is estimated to be −170 kJ mol−1.
The boron atom in BH3 has 6 valence electrons. Consequently it is a strong Lewis acid and reacts with any Lewis base, L to form an adduct.
in which the base donates its lone pair, forming a dative covalent bond. Such compounds are thermodynamically stable, but may be easily oxidised in air. Solutions containing borane dimethylsulfide and borane–tetrahydrofuran are commercially available; in tetrahydrofuran a stabilising agent is added to prevent the THF from oxidising the borane. A stability sequence for several common adducts of borane, estimated from spectroscopic and thermochemical data, is as follows:
BH3 has some soft acid characteristics as sulfur donors form more stable complexes than do oxygen donors. Aqueous solutions of BH3 are extremely unstable.
Reactions.
Molecular BH3 is believed to be a reaction intermediate in the pyrolysis of diborane to produce higher boranes:
Further steps give rise to successively higher boranes, with B10H14 as the most stable end product contaminated with polymeric materials, and a little B20H26.
Borane ammoniate, which is produced by a displacement reaction of other borane adducts, eliminates elemental hydrogen on heating to give borazine (HBNH)3.
Borane adducts are widely used in organic synthesis for hydroboration, where BH3 adds across the C=C bond in alkenes to give trialkylboranes:
This reaction is regioselective, Other borane derivatives can be used to give even higher regioselectivity. The product trialkylboranes can be converted to useful organic derivatives. With bulky alkenes one can prepare species such as [HBR2]2, which are also useful reagents in more specialised applications. Borane dimethylsulfide which is more stable than borane–tetrahydrofuran may also be used.
Hydroboration can be coupled with oxidation to give the hydroboration-oxidation reaction. In this reaction, the boryl group in the generated organoborane is substituted with a hydroxyl group.
Reductive amination is an extension of the hydroboration-oxidation reaction, wherein a carbon–nitrogen double bond is undergoing hydroboration. The carbon–nitrogen double bond is created by the reductive elimination of water from a hemiaminal, formed by the addition of an amine to a carbonyl molecule, hence the adjective 'reductive'.
Borane(5).
Borane(5) is the dihydrogen complex of borane. Its molecular formula is BH5 or possibly BH3(η2-H2). It is only stable at very low temperatures and its existence is confirmed in very low temperature. Borane(5) and methanium (CH5+) are isoelectronic. Its conjugate base is the borohydride anion.


Meso-Stilbene dibromide

"meso"-Stilbene dibromide is an organic molecule with a net formula of C14H12Br2. It is sometimes also written as "meso"-1,2-dibromo-1,2-diphenyl ethane. It appears as a white crystalline solid and can be used a building block in organic synthesis for various applications.
Synthesis.
A relatively simple way for the synthesis of "meso"-stilbene dibromide is to start from "trans"-stilbene and reacting this with bromine (Br2) in a solution of dichloromethane to perform a bromination reaction. This type of reaction should however be performed with care since elementairy bromine is very toxic and may even cause death in case of severe over-exposing
Applications.
One of the applications of "meso"-stilbene dibromide is the synthesis of diphenylacetylene by treatment with either potassium hydroxide or sodium hydroxide while heating the mixture in triethylene glycol.


Statue of Field Marshal Keith

The Statue of Field Marshal Keith is a Category B listed monument on Broad Street in Peterhead, Scotland, dedicated to James Keith, a Scottish soldier and "Generalfeldmarschall" of the Royal Prussian Army. The statue, which stands in front of Peterhead's Town House and faces east (Keith's head is turned to the northeast), was presented by William I, German Emperor. It is a zinc replica of one made of marble that originally stood in Wilhelmplatz, Berlin, but is now in the city's Bode Museum.


Tungsten(IV) oxide

Tungsten(IV) oxide is the chemical compound with the formula WO2. The bronze-colored solid crystallizes in a monoclinic cell. The rutile-like structure features distorted octahedral WO6 centers with alternate short W–W bonds (248 pm). Each tungsten center has the d2 configuration, which gives the material a high electrical conductivity.
WO2 is prepared by reduction of WO3 with tungsten powder over the course of 40 hours at 900 °C. An intermediate in this reaction is the partially reduced, mixed valence species W18O49.
The molybdenum analogue MoO2 is prepared similarly. Single crystals are obtained by chemical transport technique using iodine. Iodine transports the WO2 in the form of the volatile species WO2I2.


Zinc sulfate (medical use)

Zinc sulfate is used medically as a dietary supplement. Specifically it is used to treat zinc deficiency and to prevent the condition in those at high risk. This includes use together with oral rehydration therapy for children who have diarrhea. General use is not recommended. It may be taken by mouth or by injection into a vein.
Side effects may include abdominal pain, vomiting, headache, and feeling tired. While normal doses are deemed safe in pregnancy and breastfeeding, the safety of larger doses is unclear. Greater care should be taken in those with kidney problems. Zinc is an essential mineral in people as well as other animals.
The medical use of zinc sulfate began as early as the 1600s. It is on the World Health Organization's List of Essential Medicines. Zinc sulfate is available as a generic medication and over the counter.
Medical uses.
The use of zinc sulfate supplements together with oral rehydration therapy decreases the number of bowel movements and the time until the diarrhea stops. Its use in this situation is recommended by the World Health Organization.
There is some evidence zinc is effective in reducing hepatic and neurological symptoms of Wilson's disease.
Zinc sulfate is also an important part of parenteral nutrition.
Misuse.
During the 1918 flu pandemic in New Zealand, inhalation chambers were set up in towns and cities as a means to boost immunity. The public were encouraged to attend these chambers and inhale a zinc sulfate mist, a process that was said to disinfect the lungs and throat and protect against infection. In reality, the inhalation of zinc sulfate caused damage to the lungs and throat, thereby making participants more susceptible to infection.
In towns such as Ashburton, New Zealand for example, in order to be eligible to travel by train, people had to present documentation at the train station proving that they had been through the inhalation chamber.
The inhalation chamber which was set up in the old Dunedin Post Office building was described as follows: "It was a small room, relatively airtight, holding 20 or 30 persons, and the air is impregnated with the vapour of zinc sulphate. Each batch remains in the chamber for 10 minutes, and the persons treated are instructed to breathe through the nose at first, and then through the mouth."


Trogtalite

Trogtalite is a rare selenide mineral with the formula CoSe2. It crystallizes in the cubic system and is part of the pyrite group, consisting of Co2+ and Se22− ions. It has a rose-violet colour and its crystals are opaque. It often occurs as grains. It was thought to be dimorphous with hastite, but this was discredited in 2009. Hastite turned out to be the iron selenide mineral ferroselite. It forms a solid solution series with krut'aite.
Occurrence.
Trogtalite was first found in 1955 in Trogtal quarry, Lautenthal, Harz Mountains, Germany, after which it was also named. It often occurs intergrown with clausthalite grains at this locality. It has also been found in the Musonoi Cu–Co mine, Kolwezi, Katanga Province, Congo and in Argentina, in Tuminico, Sierra de Cacho, and in Los Llantenes, La Rioja Province. It is often found together with clausthalite, ferroselite, bornhardtite, native selenium, gold, and oosterboschite.


Rhodium(IV) oxide

Rhodium(IV) oxide (or rhodium dioxide) is the chemical compound with the formula RhO2.
Chemical properties.
RhO2 is highly insoluble even in hot aqua regia.
Structure.
RhO2 has the tetragonal rutile structure.
Physical properties.
RhO2 has metallic resistivity with values <10−4 Ohm·cm. It transforms in air to Rh2O3 at 850 °C and then to metal and oxygen at 1050 °C.


Karlsruhe Nuclide Chart

The Karlsruhe Nuclide Chart is a widespread table of nuclides in print.
Characteristics.
It is a two-dimensional graphical representation in the Segrè-arrangement with the neutron number "N" on the abscissa and the proton number "Z" on the ordinate. Each nuclide is represented at the intersection of its respective neutron and proton number by a small square box with the chemical symbol and the nucleon number "A". By columnar subdivision of such a field, in addition to ground states also nuclear isomers can be shown. The coloring of a field (segmented if necessary) shows in addition to the existing text entries the observed types of radioactive decay of the nuclide and a rough classification of their relative shares: stable, nonradioactive nuclides completely black, primordial radionuclides partially black, proton emission orange, alpha decay yellow, beta plus decay/electron capture red, isomeric transition (gamma decay, internal conversion) white, beta minus decay blue, spontaneous fission green, cluster emission violet, neutron emission light blue. For each radionuclide its field includes (if known) information about its half-life and essential energies of the emitted radiation, for stable nuclides and primordial radionuclides there are data on mole fraction abundances in the natural isotope mixture of the corresponding chemical element. Furthermore, for many nuclides cross sections for nuclear reactions with thermal neutrons are quoted, usually for the (n, γ)-reaction (neutron capture), partly fission cross sections for the induced nuclear fission and cross sections for the (n, α)-reaction or (n, p)-reaction. For the chemical elements cross sections and standard atomic weights (both averaged over natural isotopic composition) are specified (the relative atomic masses partially as an interval to reflect the variability of the composition of the element's natural isotope mixture). For the nuclear fission of 235U and 239Pu with thermal neutrons, percentage isobaric chain yields of fission products are listed.
History, editions.
The first printed edition of the Karlsruhe Nuclide Chart of 1958 in the form of a wall chart was created by Walter Seelmann-Eggebert and his assistant Gerda Pfennig. Walter Seelmann-Eggebert was director of the Radiochemistry Institute in the 1956 founded "Kernreaktor Bau- und Betriebsgesellschaft mbH" in Karlsruhe, Germany (a predecessor institution of the later "(Kern-)Forschungszentrum Karlsruhe", nowadays Karlsruhe Institute of Technology) and appointed professor of radiochemistry at the Karlsruhe Technical University. Radiochemical isotope courses were held at the institute, and in the context of these teaching courses the Karlsruhe Nuclide Chart arose, which was intended to be a well-structured overview of the essential properties of the nuclides already known at that time.
In the following decades, the Karlsruhe Nuclide Chart was published and revised several times. In addition to other co-authors, Seelmann-Eggebert († 1988) was involved up to the 5th edition in 1981, Pfennig († 2017) up to the 9th edition in 2015. In 2006, the management of the Karlsruhe Nuclide Chart changed over from Forschungszentrum Karlsruhe to the Institute for Transuranium Elements (ITU) of the Joint Research Centre (JRC) of the European Commission (EC), then in 2012 to Nucleonica GmbH, a spin-off company of the JRC-ITU.
The following summary table regarding the individual editions of the Karlsruhe Nuclide Chart also expresses the scientific progress in the field of discovery/exploration of the nuclides and new chemical elements.
Versions.
The Karlsruhe Nuclide Chart is primarily published as a fold-out chart (size A4) or as a wall chart (size 0.96 m × 1.40 m). There are also larger sizes (roll map, auditorium chart and "carpet"). Since 2014, an internet-based version "Karlsruhe Nuclide Chart Online (KNCO)" with regular updates is offered via the Nucleonica nuclear science internet portal.


Disilyne

Disilyne is a silicon hydride with the formula . Several isomers are possible, but none are sufficiently stable to be of practical value. Substituted disilynes contain a formal silicon–silicon triple bond and as such are sometimes written R2Si2 (where R is a substituent group). They are the silicon analogues of alkynes.
The term "silyne" has two diverse meanings. Some chemists use it to refer to compounds containing a silicon–silicon triple bond, whereas others use the term to refer to compounds containing a silicon–carbon triple bond by analogy to silene, which often refers to compounds containing silicon–carbon double bonds. The term polysilyne can refer to the layer polymer (SiH)n or substituted derivatives.
Substituted disilynes.
The first example isolated and characterised by X-ray crystallography is an emerald green crystalline compound reported in 2004.
This molecule has the formula <chem>R'_2R"Si-Si#Si-SiR"R'_2</chem>, where <chem>R'</chem> = HC(SiMe3)2 and <chem>R"</chem> = HCMe2.
It was prepared by the reduction of the related tetrabrominated precursor by potassium graphite (KC8). It is air- and moisture-sensitive but is a stable solid up to 128 °C.
The geometry of the central four-silicon chain is unlike that of analogous carbon structures. Whereas substituted alkynes are linear, having a 180° bond angle at each end of the carbon–carbon triple bond, the silicon chain is bent to 137° at each end. The four silicon atoms in the chain are however perfectly coplanar, with the first and fourth silicon atoms "trans" to one another. The central triple bond length is 206 pm, which is around 4% shorter than the typical bond-length of Si–Si double bonds (214 pm)) and the Si–Si single bonds are 237 pm. The colour is attributed to a weak π–π* transition.
Calculations show a bond order of 2.6. An alternative calculation of the bond order by a different group describes the bonding as essentially due to only two electron pairs, with the third pair in a non-bonding orbital. Reaction of this compound with phenylacetylene produced a 1,2 disilabenzene.
Other workers
have also reported another related compound which contains a hexasila-3-yne chain:
In this compound, the Si–Si triple bond length was calculated as 207 pm.
Heavier group 14 analogues.
Triple bonded compounds of the heavier members of group 14 have also been prepared; lead,
 and tin and germanium (digermyne) The cores of the disilyne, digermyne, distannyne, and diplumbyne have similarly bent geometries. These findings are generally consistent with the absence of conventional triple bonds.


Organolead compound

Organolead compounds are chemical compounds containing a chemical bond between carbon and lead. Organolead chemistry is the corresponding science. The first organolead compound was hexaethyldilead (Pb2(C2H5)6), first synthesized in 1858. Sharing the same group with carbon, lead is tetravalent.
Going down the carbon group the C–"X" ("X" = C, Si, Ge, Sn, Pb) bond becomes weaker and the bond length larger. The C–Pb bond in tetramethyllead is 222 pm long with a dissociation energy of 49 kcal/mol (204 kJ/mol). For comparison the C–Sn bond in tetramethyltin is 214 pm long with dissociation energy 71 kcal/mol (297 kJ/mol). The dominance of Pb(IV) in organolead chemistry is remarkable because inorganic lead compounds tend to have Pb(II) centers. The reason is that with inorganic lead compounds elements such as nitrogen, oxygen and the halides have a much higher electronegativity than lead itself and the partial positive charge on lead then leads to a stronger contraction of the 6s orbital than the 6p orbital making the 6s orbital inert; this is called the inert pair effect.
By far the most important organolead compound is tetraethyllead, formerly used as an antiknock agent in gasoline intended for internal combustion engines. The most important lead reagents for introducing lead are lead tetraacetate and lead chloride.
The use of organoleads is limited partly due to their toxicity.
Synthesis.
Organolead compounds can be derived from Grignard reagents and lead chloride. For example, methylmagnesium chloride reacts with lead chloride to tetramethyllead, a water-clear liquid with boiling point 110 °C and density 1.995 g/cm³. Reaction of a lead(II) source with sodium cyclopentadienide gives the lead metallocene, plumbocene.
Certain arene compounds react directly with lead tetraacetate to aryl lead compounds in an electrophilic aromatic substitution. For instance anisole with lead tetraacetate forms 'p-methoxyphenyllead triacetate in chloroform and dichloroacetic acid:
Other compounds of lead are organolead halides of the type RnPbX(4-n), organolead sulfinates (RnPb(OSOR)(4−n)) and organolead hydroxides (RnPb(OH)(4−n)). Typical reactions are:
 compounds are amphoteric. At pH lower than 8 they form R2Pb2+ ions and with pH higher than 10, R2Pb(OH)3− ions.
Derived from the hydroxides are the plumboxanes:
which give access to polymeric alkoxides:
Reactions.
The C–Pb bond is weak and for this reason homolytic cleavage of organolead compounds to free radicals is easy. In its anti-knocking capacity, its purpose is that of a radical initiator. General reaction types of aryl and vinyl organoleads are transmetalation for instance with boronic acids and acid-catalyzed heterocyclic cleavage. Organoleads find use in coupling reactions between arene compounds. They are more reactive than the likewise organotins and can therefore be used to synthesise sterically crowded biaryls.
In oxyplumbation, organolead alkoxides are added to polar alkenes:
The alkoxide is regenerated in the subsequent methanolysis and, therefore, acts as a catalyst.
Aryllead triacetates.
The lead substituent in "p"-methoxyphenyllead triacetate is displaced by carbon nucleophiles, such as the phenol mesitol, exclusively at the aromatic ortho position:
The reaction requires the presence of a large excess of a coordinating amine such as pyridine which presumably binds to lead in the course of the reaction. The reaction is insensitive to radical scavengers and therefore a free radical mechanism can be ruled out. The reaction mechanism is likely to involve nucleophilic displacement of an acetate group by the phenolic group to a diorganolead intermediate which in some related reactions can be isolated. The second step is then akin to a Claisen rearrangement except that the reaction depends on the electrophilicity (hence the ortho preference) of the phenol.
The nucleophile can also be the carbanion of a β-dicarbonyl compound:
The carbanion forms by proton abstraction of the acidic α-proton by pyridine (now serving a double role) akin to the Knoevenagel condensation. This intermediate displaces an acetate ligand to a diorganolead compound and again these intermediates can be isolated with suitable reactants as unstable intermediates. The second step is reductive elimination with formation of a new C–C bond and lead(II) acetate.
Reactive intermediates.
Organolead compounds form a variety of reactive intermediates such as lead free radicals:
and plumbylenes, the lead carbene counterparts:
These intermediates break up by disproportionation.
Plumbylidines of the type RPb (formally Pb(I)) are ligands to other metals in LnMPbR compounds (compare to carbon metal carbynes).


Tungsten(IV) chloride

Tungsten(IV) chloride is an inorganic compound with the formula WCl4. It is a diamagnetic black solid. The compound is of interest in research as one of a handful of binary tungsten chlorides.
Structure and preparation.
WCl4 is usually prepared by reduction tungsten hexachloride. Many reductants have been reported, including red phosphorus, tungsten hexacarbonyl, gallium, tin, and antimony. The latter is reported to be optimal:
Like most binary metal halides, WCl4 is polymeric. It consists of linear chains of tungsten atoms each in octahedral geometry. Of six chloride ligands attached to each W center, four are bridging ligands. The W-W separations are alternatingly bonding (2.688 Å) and nonbonding (3.787 Å).
Reactions.
Reduction of tungsten(IV) chloride with sodium yields the ditungsten(III) heptachloride derivative:


YF-75

The YF-75 is a liquid cryogenic rocket engine burning liquid hydrogen and liquid oxygen in a gas generator cycle. It is China's second generation of cryogenic propellant engine, after the YF-73, which it replaced. It is used in a dual engine mount in the H-18 third stage of the Long March 3A, Long March 3B and Long March 3C launch vehicles. Within the mount, each engine can gimbal individually to enable thrust vectoring control. The engine also heats hydrogen and helium to pressurize the stage tanks and can control the mixture ratio to optimize propellant consumption.
Development.
Given the upward trend on geosynchronous communication satellite's mass and size, a program to develop an engine more powerful than the YF-73 was started by 1982. The proper development of the engine started in 1986 and leveraged the experience of the YF-73. It flew for the first time in 1994. By September 2013, it had accumulated 12 start up and 3,000 seconds of firing time without malfunction.
By 2006 and with the project for the Long March 5 family a serious redesign program was started. The resulting engine, the YF-75D is a different engine, using a closed circuit expander cycle like the RL10.
Technical Description.
The combustion chamber regeneratively cooled and is made of a zirconium copper alloy. It is manufactured by forging, rolled into shape, and then the cooling channels are milled. The outer wall is electroformed nickel. The nozzle extension uses dump cooling. It is made by welding spiraling tubes which pass cryogenic hydrogen that is dumped since the tubes are open at the bottom. The gas generator feed separate turbopumps for fuel and oxidizer. The single shaft hydrogen turbopump operates at 42,000rpm and uses dual elastic supports to enhance the rotor stability and reliability. The gas generator also incorporates dual heat exchanger that heat hydrogen gas and helium supplied from separate system to pressurize the hydrogen and oxygen tanks.
The turbopumps use solid propellant cartridge for start up, while the gas generator and combustion chamber use pyrotechnic igniter. It can restart for two burn profile missions. All subsystems are attached to the combustion chamber and gimbal is achieved by rotating the whole engine on two orthogonal planes with two independent actuators. These actuators use high pressure hydrogen as hydraulic fluid. The oxygen supply system has a propellant utilization valve before the main LOX valve to regulate its flow and thus variate the mixture ratio. This enables optimization of the propellant reserves and improves performance.


Boranes

Boranes is the name given to the class of synthetic hydrides of boron with generic formula BxHy. In the past, borane molecules were often labeled "electron-deficient" because of their multicenter bonding (in which a pair of bonding electrons links more than two atoms, as in 3-center-2-electron bonds); this was done in order to distinguish such molecules from hydrocarbons and other classically bonded compounds. However, this usage is incorrect, as most boranes and related clusters such as carboranes are actually "electron-precise", not electron-deficient. For example, the extremely stable icosahedral B12H122− dianion, whose 26 cluster valence electrons exactly fill the 13 bonding molecular orbitals, is in no actual sense deficient in electrons; indeed it is thermodynamically far more stable than benzene.
While some boranes are highly reactive with respect to electron-pair donors, others are not, e.g., the BnHn2− dianions (n = 6-12) as well as many neutral boranes such as B18H22. Some lower boranes are pyrophoric in air and react with water. The boranes belong to the class of cluster compounds, which have been the subject of developments in chemical bonding theory. Many of the related anionic hydridoborates have also been synthesized.
History.
The development of the chemistry of boranes presented a number of challenges. First, new laboratory techniques had to be developed to handle these often pyrophoric compounds. Alfred Stock created the glass vacuum line, now known as a Schlenk line, for synthesis and handling. The very reactive nature of the lower boranes meant that crystal structure determination was impossible before William Lipscomb developed the requisite techniques. Lastly, once the structures were known it became clear that new theories of chemical bonding were needed to explain them. Lipscomb was awarded the Nobel prize in Chemistry in 1976 for his achievements in this field.
The correct structure of diborane was predicted by H. Christopher Longuet-Higgins 5 years before its determination. Polyhedral skeletal electron pair theory (Wade's rules) can be used to predict the structures of boranes.
Interest in boranes increased during World War II due to the potential of uranium borohydride for enrichment of the uranium isotopes. In the US, a team led by Schlesinger developed the basic chemistry of the boron hydrides and the related aluminium hydrides. Although uranium borohydride was not utilized for isotopic separations, Schlesinger's work laid the foundation for a host of boron hydride reagents for organic synthesis, most of which were developed by his student Herbert C. Brown. Borane-based reagents are now widely used in organic synthesis. Brown was awarded the Nobel prize in Chemistry in 1979 for this work.
Chemical formula and naming conventions.
Borane clusters are classified as follows, where "n" is the number of boron atoms in a single cluster:
The International Union of Pure and Applied Chemistry rules for systematic naming is based on a prefix denoting a class of compound, followed by the number of boron atoms and finally the number of hydrogen atoms in parentheses. Various details can be omitted if there is no ambiguity about the meaning, for example, if only one structural type is possible. Some examples of the structures are shown below.
The naming of anions is illustrated by
The hydrogen count is specified first followed by the boron count. The -ate suffix is applied with anions. The ionic charge value is included in the chemical formula but not as part of the systematic name.
Bonding in boranes.
Boranes are nonclassically–bonded compounds, that is, there are not enough electrons to form 2-centre, 2-electron bonds between all pairs of adjacent atoms in the molecule. A description of the bonding in the larger boranes was formulated by William Lipscomb. It involved:
Lipscomb's methodology has largely been superseded by a molecular orbital approach. This allows the concept of multi-centre bonding to be extended. For example, in the icosahedral ion [B12H12]2-, the totally symmetric (Ag symmetry) molecular orbital is equally distributed among all 12 boron atoms. Wade's rules provide a powerful method that can be used to rationalize the structures in terms of the number of atoms and the connectivity between them.
There are continuing efforts by theoretical chemists to improve the treatment of the bonding in boranes—an example is Stone's tensor surface harmonic treatment of cluster bonding. A recent development is four-center two-electron bond.
Reactivity of boranes.
The lowest borane, BH3, is a very strong Lewis acid. The molecule itself exists only transiently, dimerizing instantly to form diborane, B2H6, but its adducts BH3·THF and BH3·DMSO are stable enough to be used in hydroboration reactions. Other boranes are electrophilic and react vigorously with reagents that can supply electron pairs. With an alkali metal hydride, for example,
Further demonstrating that they are "not" in general "electron-deficient" (see above), boranes can also function as "electron donors" owing to the relative basic character of the low-polarity B-Hterminal groups, as in reactions with halogens to form haloboranes.
The reaction of some lower boranes with air is strongly exothermic; those of B2H6 and B5H9, for example, occur explosively except in very low concentration. This does not result from any inherent instability in the boranes. Rather, it is a consequence of the fact that a combustion product, boron trioxide, is a solid. For example
The formation of the solid releases additional energy to what is released by the oxidation reaction. By contrast, many "closo"-borane anions, such as B12H122−, do not react with air; salts of these anions are metastable because the "closo"- structure creates a very high activation energy barrier to oxidation.
The higher boranes can be deprotonated when treated with a very strong base. For example,
They can also act as weak acids. For example, pentaborane(9) reacts with trimethylphosphine
producing what can be regarded as a derivative of the unknown "hypho"-borane B5H13. Acidity increases with the size of the borane. B10H14 has a pK value of 2.7 temperature not stated.
Reaction of a borane with the transient BH3, produced by dissociation of B2H6, can lead to the formation of a "conjuncto"-borane species in which two small borane sub-units are joined by the sharing of boron atoms.
Other "conjuncto"-boranes, where the sub-units are joined by a B-B bond, can be made by ultra violet irradiation of "nido"-boranes. Some B-B coupled "conjuncto"-boranes can be produced using PtBr2 as catalyst.
Reaction of a borane with an alkyne can produce a carborane; the icosahedral closo-carboranes C2B10H12, are particularly stable.
Boranes can function as ligands in coordination compounds. Hapticities of η1 to η6 have been found, with electron donation involving bridging H atoms or donation from B-B bonds. For example, "nido-"B6H10 can replace ethene in Zeise's salt to produce Fe(η2-B6H10)(CO)4.
Applications.
The main chemical application of boranes is the hydroboration reaction. Commercially available adducts such as borane–tetrahydrofuran or borane–dimethylsulfide are often used in this context as they have comparable effectiveness but without the hazard of handling highly reactive BH3 itself.
Neutron capture therapy of cancer is a promising development. The compound used is the HS– (bisulfide) derivative Na2[B12H11(SH)]. It makes use of the fact that 10B has a very high neutron-capture cross section, so neutron irradiation is highly selective for the region where the compound resides.
Boranes have a high specific energy of combustion compared to hydrocarbons, making them potentially attractive as fuels. Intense research was carried out in the 1950s into their use as jet fuel additives, but the effort did not lead to practicable results.


Strontium acetate

Strontium acetate is a compound of strontium. It is a white solid and is soluble in water like other acetates. It is used as a pathway for other chemicals such as barium acetate.
Preparation.
Strontium acetate is formed by reacting strontium hydroxide or strontium carbonate in acetic acid.


Suanite

Suanite is a magnesium borate mineral with formula Mg2B2O5.
It was first described in 1953 by Japanese scientist Takeo Watanabe from the University of Tokyo.
His first contact with the mineral was during analysis of gold- and copper- bearing skarn minerals from the Hol Kol mine, located in North Korea obtained in 1939. Due to the small sample size available to him, he was only able to determine the unknown substance's optical properties under a microscope. Watanabe was able to return to the site in 1943 and obtain further samples that permitted him to perform chemical analysis on the material.


Nitrogen-doped carbon nanotube

Nitrogen-doped carbon nanotubes (N-CNTs) can be produced through five main methods; chemical vapor deposition, high-temperature and high-pressure reactions, gas-solid reaction of amorphous carbon with NH3 at high temperature, solid reaction, and solvothermal synthesis.
N-CNTs can also be prepared by a CVD method of pyrolyzing melamine under Ar at elevated temperatures of 800–980 °C. However synthesis by CVD of melamine results in the formation of bamboo-structured CNTs. XPS spectra of grown N-CNTs reveal nitrogen in five main components, pyridinic nitrogen, pyrrolic nitrogen, quaternary nitrogen, and nitrogen oxides. Furthermore, synthesis temperature affects the type of nitrogen configuration.
Nitrogen doping plays a pivotal role in lithium storage, as it creates defects in the CNT walls allowing for Li ions to diffuse into interwall space. It also increases capacity by providing more favorable bind of N-doped sites. N-CNTs are also much more reactive to metal oxide nanoparticle deposition which can further enhance storage capacity, especially in anode materials for Li-ion batteries. However boron-doped nanotubes have been shown to make batteries with triple capacity.


Axinite

Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH. Axinite is pyroelectric and piezoelectric.
The axinite group includes:
Axinite is sometimes used as a gemstone.


Magnesium glycinate

Magnesium glycinate, also known as magnesium diglycinate or magnesium bisglycinate, is the magnesium salt of glycine (one magnesium and two glycine molecules), and is sold as a dietary supplement. It contains 14.1% elemental magnesium by mass. Accordingly, 141 mg of elemental magnesium is contained in 1000 mg of magnesium glycinate.
Uses.
Magnesium glycinate has been studied with applicability to patients with a bowel resection or pregnancy-induced leg cramps.


Sweetite

Sweetite has a general formula of Zn(OH)2. The name is given after a curator of mineral department of The British Museum, Jessie May Sweet (1901–1979). It occurs in an oxidized vein in limestone bedrock with galena, ashoverite, wülfingite, anglesite, cerussite, hydrocerussite, litharge, fluorite, palygorskite and calcite.
Sweetite is tetragonal, which means crystallographically it contains one axis of unequal length and two axes of equal length. The angles between three of the axes are all 90°. It belongs to the space group 4/m. Some crystals show evidence of a basal plane and a few are tabular. In terms of its optical properties, sweetite has two indices of refraction, 1.635 along the ordinary ray and 1.628 along the extraordinary ray. The index of refraction is the velocity of light in a vacuum divided by the velocity of light in medium. It also has the birefringence of 0.007. The birefringence means the decomposition of light into two rays when passing through a mineral. Sweetite is 1.64 - 1.65 in relief, which is medium to high in intensity and means a measure of the relative difference between the index of refraction of a mineral and its surrounding medium.
Sweetite is mostly found from a limestone quarry 200–300 m northwest of Milltown, near Ashover, Derbyshire, England.


Jadeite

Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4.
Name.
The name "jadeite" is derived (via and ) from the Spanish phrase "piedra de ijada" which means "stone of the side". The Latin version of the name, "lapis nephriticus", is the origin of the term nephrite, which is a different mineral that also shares the common name jade.
Chemistry.
Jadeite forms solid solutions with other pyroxene endmembers such as augite and diopside (CaMg-rich endmembers), aegirine (NaFe endmember), and kosmochlor (NaCr endmember). Pyroxenes rich in both the jadeite and augite endmembers are known as omphacite. Jadeite is formed in metamorphic rocks under high pressure and relatively low temperature conditions. Albite (NaAlSi3O8) is a common mineral of the Earth's crust, and it has a specific gravity of about 2.6, much less than that of jadeite. With increasing pressure, albite breaks down to form the high-pressure assemblage of jadeite plus quartz. Minerals associated with jadeite include: glaucophane, lawsonite, muscovite, aragonite, serpentine and quartz.
Rocks that consist almost entirely of jadeite are called jadeitite. In all well-documented occurrences, jadeitite appears to have formed from subduction zone fluids in association with serpentinite. Jadeitite is resistant to weathering, and boulders of jadeitite released from the serpentine-rich environments in which they formed are found in a variety of environments.
Colors.
Jadeite's color commonly ranges from white through pale apple green to deep "jade" green but can also be blue-green (like the recently rediscovered "Olmec Blue" jade), pink, lavender and a multitude of other rare colors. "Chloromelanite" is a very dark green to black variety. Color is largely affected by the presence of trace elements such as chromium and iron. Its translucence varies from opaque to almost clear. Variations in color and translucence are often found even within a single specimen. Jadeite is reported from California, US; Myanmar; New Zealand; Guatemala; Itoigawa, Japan; other localities of jadeite include Kazakhstan; Russia; British Columbia, Canada; Italy and Turkestan.
Stone Age use.
Over 180 axe heads made from jadeitite quarried in northern Italy in the Neolithic era have been found across the British Isles. Because of the difficulty of working this material, all the axe heads of this type found are thought to have been non-utilitarian and to have represented some form of currency or be the products of gift exchange.
A great many jadeite beads and axe heads as well as the remains of jadeite workshops from the Neolithic era have been uncovered in Itoigawa, Japan. These beads and axes were traded throughout Japan and the Korean Peninsula and were produced by the world's oldest known jadeite-using culture, centered on the Itoigawa region.
Jade.
Jadeite is one of two minerals recognized as the gemstone jade. The other is nephrite. Jadeite from the Motagua Valley, Guatemala, was used by the Olmec and Maya peoples, as well as the indigenous peoples of Costa Rica. In the West, the most highly valued colors of jadeite are the intensely green, translucent varieties, though traditionally white has been considered the most valuable of the jades by the Chinese.
Other colors, like "Olmec blue" jade, which is characterized by its deep blue-green, translucent hue with white flecking, are also becoming more highly valued because of its unique beauty and historical use by the Mesoamerican Olmec and also in Costa Rica; however, this variety was only recently rediscovered and is only being minimally exploited by native Guatemalans. It is thus difficult to obtain and as yet too rare and little known to have attained great value as a gemstone.
The commercial quality of jade is determined by the degree of translucence, cleanness of color and purity of color. Occasionally, other minerals such as serpentine or quartz are sold as jade, but the difference can be determined by cleavage and hardness. High-quality jade made from jadeite can cost upwards of US$30,000 per carat.


Zirconate

A zirconate is an oxyanion containing zirconium. Examples include Na2ZrO3, Ca2ZrO4 which can be prepared by fusing zirconium dioxide with e.g. Na2O and CaO respectively.


Pentamethylmolybdenum

Pentamethylmolybdenum is an organomolybdenum compound containing five methyl groups bound to a central molybdenum atom. The shape of the molecule is a square pyramid.
The molecule is similar to pentamethyltungsten in shape and properties.
Production.
Pentamethylmolybdenum can be prepared from molybdenum pentachloride and dimethyl zinc at low temperature between −70 and −20. Another possible creation route, is from molybdenum oxychloride. Pentamethylmolybdenum is paramagnetic with one unpaired electron. The character of this electron is two thirds 4dz2 and one third 4dx2−y2.
Properties.
Pentamethylmolybdenum is unstable and sensitive to oxygen. It turns black when exposed to air, or heated over −10°C.
The Raman spectrum has bands at 1181, 960, 90, 882, 783, 672, 620, 565, 523, 507, 451, 366, 308, 267 and 167  cm−1.


Unseptnilium


Sulfate

The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid.
Spelling.
"Sulfate" is the spelling recommended by IUPAC, but "sulphate" was traditionally used in British English.
Structure.
The sulfate anion consists of a central sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry is the same as that of methane. The sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the −2 state. The sulfate ion carries an overall charge of −2 and it is the conjugate base of the bisulfate (or hydrogen sulfate) ion, , which is in turn the conjugate base of , sulfuric acid. Organic sulfate esters, such as dimethyl sulfate, are covalent compounds and esters of sulfuric acid. The tetrahedral molecular geometry of the sulfate ion is as predicted by VSEPR theory.
Bonding.
The first description of the bonding in modern terms was by Gilbert Lewis in his groundbreaking paper of 1916 where he described the bonding in terms of electron octets around each atom, that is no double bonds and a formal charge of +2 on the sulfur atom.
Later, Linus Pauling used valence bond theory to propose that the most significant resonance canonicals had two pi bonds involving d orbitals. His reasoning was that the charge on sulfur was thus reduced, in accordance with his principle of electroneutrality. The S−O bond length of 149 pm is shorter than the bond lengths in sulfuric acid of 157 pm for S−OH. The double bonding was taken by Pauling to account for the shortness of the S−O bond. Pauling's use of d orbitals provoked a debate on the relative importance of pi bonding and bond polarity (electrostatic attraction) in causing the shortening of the S−O bond. The outcome was a broad consensus that d orbitals play a role, but are not as significant as Pauling had believed.
A widely accepted description involving pπ – dπ bonding was initially proposed by Durward William John Cruickshank. In this model, fully occupied p orbitals on oxygen overlap with empty sulfur d orbitals (principally the d"z"2 and d"x"2–"y"2). However, in this description, despite there being some π character to the S−O bonds, the bond has significant ionic character. For sulfuric acid, computational analysis (with natural bond orbitals) confirms a clear positive charge on sulfur (theoretically +2.45) and a low 3d occupancy. Therefore, the representation with four single bonds is the optimal Lewis structure rather than the one with two double bonds (thus the Lewis model, not the Pauling model). In this model, the structure obeys the octet rule and the charge distribution is in agreement with the electronegativity of the atoms. The discrepancy between the S−O bond length in the sulfate ion and the S−OH bond length in sulfuric acid is explained by donation of p-orbital electrons from the terminal S=O bonds in sulfuric acid into the antibonding S−OH orbitals, weakening them resulting in the longer bond length of the latter.
However, the bonding representation of Pauling for sulfate and other main group compounds with oxygen is still a common way of representing the bonding in many textbooks. The apparent contradiction can be cleared if one realizes that the covalent double bonds in the Lewis structure in reality represent bonds that are strongly polarized by more than 90% towards the oxygen atom. On the other hand, in the structure with a dipolar bond, the charge is localized as a lone pair on the oxygen.
Preparation.
Methods of preparing metal sulfates include:
Properties.
There are numerous examples of ionic sulfates, many of which are highly soluble in water. Exceptions include calcium sulfate, strontium sulfate, lead(II) sulfate, and barium sulfate, which are poorly soluble. Radium sulfate is the most insoluble sulfate known. The barium derivative is useful in the gravimetric analysis of sulfate: if one adds a solution of most barium salts, for instance barium chloride, to a solution containing sulfate ions, barium sulfate will precipitate out of solution as a whitish powder. This is a common laboratory test to determine if sulfate anions are present.
The sulfate ion can act as a ligand attaching either by one oxygen (monodentate) or by two oxygens as either a chelate or a bridge. An example is the complex [Co(en)2(SO4)]+Br− or the neutral metal complex PtSO4(P(C6H5)3)2 where the sulfate ion is acting as a bidentate ligand. The metal–oxygen bonds in sulfate complexes can have significant covalent character.
Uses and occurrence.
Commercial applications.
Sulfates are widely used industrially. Major compounds include:
Occurrence in nature.
Sulfate-reducing bacteria, some anaerobic microorganisms, such as those living in sediment or near deep sea thermal vents, use the reduction of sulfates coupled with the oxidation of organic compounds or hydrogen as an energy source for chemosynthesis.
History.
Some sulfates were known to alchemists. The vitriol salts, from the Latin "vitreolum", glassy, were so-called because they were some of the first transparent crystals known. Green vitriol is iron(II) sulfate heptahydrate, FeSO4·7H2O; blue vitriol is copper(II) sulfate pentahydrate, CuSO4·5H2O and white vitriol is zinc sulfate heptahydrate, ZnSO4·7H2O. Alum, a double sulfate of potassium and aluminium with the formula K2Al2(SO4)4·24H2O, figured in the development of the chemical industry.
Environmental effects.
Sulfates occur as microscopic particles (aerosols) resulting from fossil fuel and biomass combustion. They increase the acidity of the atmosphere and form acid rain. The anaerobic sulfate-reducing bacteria "Desulfovibrio desulfuricans" and "D. vulgaris" can remove the black sulfate crust that often tarnishes buildings.
Main effects on climate.
The main direct effect of sulfates on the climate involves the scattering of light, effectively increasing the Earth's albedo. This effect is moderately well understood and leads to a cooling from the negative radiative forcing of about 0.4 W/m2 relative to pre-industrial values, partially offsetting the larger (about 2.4 W/m2) warming effect of greenhouse gases. The effect is strongly spatially non-uniform, being largest downstream of large industrial areas.
The first indirect effect is also known as the Twomey effect. Sulfate aerosols can act as cloud condensation nuclei and this leads to greater numbers of smaller droplets of water. Many smaller droplets can diffuse light more efficiently than a few larger droplets.
The second indirect effect is the further knock-on effects of having more cloud condensation nuclei. It is proposed that these include the suppression of drizzle, increased cloud height, to facilitate cloud formation at low humidities and longer cloud lifetime. Sulfate may also result in changes in the particle size distribution, which can affect the clouds radiative properties in ways that are not fully understood. Chemical effects such as the dissolution of soluble gases and slightly soluble substances, surface tension depression by organic substances and accommodation coefficient changes are also included in the second indirect effect.
The indirect effects probably have a cooling effect, perhaps up to 2 W/m2, although the uncertainty is very large. Sulfates are therefore implicated in global dimming. Sulfate is also the major contributor to stratospheric aerosol formed by oxidation of sulfur dioxide injected into the stratosphere by impulsive volcanoes such as the 1991 eruption of Mount Pinatubo in the Philippines. This aerosol exerts a cooling effect on climate during its 1-2 year lifetime in the stratosphere.
Hydrogen sulfate (bisulfate).
The conjugate base of sulfuric acid (H2SO4)—a dense, colourless, oily, corrosive liquid—is the hydrogen sulfate ion (), also called the bisulfate ion. Sulfuric acid is classified as a strong acid; in aqueous solutions it ionizes completely to form hydronium ions (H3O+) and hydrogen sulfate (). In other words, the sulfuric acid behaves as a Brønsted–Lowry acid and is deprotonated. Bisulfate has a molar mass of 97.078 g/mol. It has a valency of 1. An example of a salt containing the group is sodium bisulfate, NaHSO4. In dilute solutions the hydrogen sulfate ions also dissociate, forming more hydronium ions and sulfate ions (). The CAS registry number for hydrogen sulfate is 14996-02-2.


Calcium encoding

Calcium encoding (also referred to as Ca2+ encoding or calcium information processing) is an intracellular signaling pathway used by many cells to transfer, process and encode external information detected by the cell. In cell physiology, external information is often converted into intracellular calcium dynamics. The concept of calcium encoding explains how Ca2+ ions act as intracellular messengers, relaying information within cells to regulate their activity. Given the ubiquity of Ca2+ ions in cell physiology, Ca2+ encoding has also been suggested as a potential tool to characterize cell physiology in health and disease. The mathematical bases of Ca2+ encoding have been pioneered by work of Joel Keizer and Hans G. Othmer on calcium modeling in the 1990s and more recently they have been revisited by Eshel Ben-Jacob, Herbert Levine and co-workers.
AM, FM and AFM calcium encoding.
Although elevations of Ca2+ are necessary for it to act as a signal, prolonged increases of the concentration of Ca2+ in the cytoplasm can be lethal for the cell. Thus cells avoid death usually delivering Ca2+ signals as brief transients - i.e. Ca2+ elevations followed by a rapid decay - or in the form of oscillations. In analogy with Information Theory, either the amplitude or the frequency or both features of these Ca2+ oscillations define the Ca2+ encoding mode. Therefore, three classes of Ca2+ signals can be distinguished on the basis of their encoding mode:
Experiments and biophysical modeling, show that the mode of calcium encoding varies from cell to cell, and that a given cell could even show different types of calcium encoding for different patho-physiological conditions. This could ultimately provide a crucial tool in medical diagnostics, to characterize, recognize and prevent diseases.
Mathematical aspects of calcium encoding.
Calcium encoding can be mathematically characterized by biophysical models of calcium signaling. Phase plane and bifurcation analysis of these models, can reveal in fact how frequency and amplitude of calcium oscillations vary as a function of any parameter of the model. Occurrence of AM-, FM- or AFM-encoding can be assessed on the extension of the min-max range of amplitude and frequency of Ca2+ oscillations and the bifurcation structure of the system under study.
A critical aspect of Ca2+ encoding revealed by modeling, is how it depends on the dynamics of the complex network of reactions of underlying Ca2+-mobilizing signals. This aspect can be addressed considering Ca2+ models that include both Ca2+ dynamics and the dynamics of Ca2+-mobilizing signals. One simple and biophysically realistic model of this kind is the "ChI model", originally developed by Eshel Ben-Jacob and co-workers, for GPCR-mediated inositol 1,4,5 trisphospate (IP3)-triggered Ca2+-induced Ca2+-release. The main conclusion of this study was that the dynamics of the Ca2+-mobilizing IP3 signal is essentially AFM encoding with respect to the stimulus whereas Ca2+ oscillations can be either FM or AFM but not solely AM. It was argued that the AFM nature of the Ca2+-mobilizing IP3 signal could represent the ideal solution to optimally translate pulsed or discontinuous extracellular signals into intracellular continuous-like Ca2+ oscillations.
Computational aspects.
Calcium encoding can be confined within a single cell or involve cell ensembles and deploy essential computational tasks, such as stimulus integration or regulated activation of gene transcription. Moreover, cells are often organized in networks, allowing intercellular propagation of calcium signaling. With this regard, the same mode of calcium encoding could be shared by different cells, providing synchronization or the functional basis to implement more complex computational tasks.
Michael Forrest has shown that intracellular calcium dynamics may permit a Purkinje neuron to perform toggle and gain computations upon its inputs. So, showing how an ion concentration can be used as a computational variable - in particular, as a memory element: recording a history of firing and inputs, to dictate how the neuron responds to future inputs. Thus, this work hypothesizes that the membrane potential (V) is not the Purkinje cell's only coding variable but works alongside a calcium memory system. These two interact, with the calcium memory being encoded and decoded by the membrane potential. The toggle and gain computations are likely to be salient to network computations in the cerebellum, in the brain. Thus, ion computations can be important more globally than a single cell. Forrest terms this hypothesis: "ion to network computation".


Laureate (Lipton)

Laureate is a public art work by American artist Seymour Lipton, located on the Riverwalk in downtown Milwaukee, Wisconsin. The abstract artwork was commissioned by the Allen-Bradley Company in memory of Harry Lynde Bradley and as an enhancement for the newly constructed Performing Arts Center. It is located on the east bank of the Milwaukee River at 929 North Water Street.


Protium (isotope)


Smithsonite

Smithsonite, also known as turkey fat or zinc spar, is zinc carbonate (ZnCO3), a mineral ore of zinc. Historically, smithsonite was identified with hemimorphite before it was realized that they were two different minerals. The two minerals are very similar in appearance and the term calamine has been used for both, leading to some confusion. The distinct mineral smithsonite was named in 1832 by François Sulpice Beudant in honor of English chemist and mineralogist James Smithson (c.1765–1829), whose bequest established the Smithsonian Institution and who first identified the mineral in 1802.
Smithsonite is a variably colored trigonal mineral which only rarely is found in well formed crystals. The typical habit is as earthy botryoidal masses. It has a Mohs hardness of 4.5 and a specific gravity of 4.4 to 4.5.
Smithsonite occurs as a secondary mineral in the weathering or oxidation zone of zinc-bearing ore deposits. It sometimes occurs as replacement bodies in carbonate rocks and as such may constitute zinc ore. It commonly occurs in association with hemimorphite, willemite, hydrozincite, cerussite, malachite, azurite, aurichalcite and anglesite. It forms two limited solid solution series, with substitution of manganese leading to rhodochrosite, and with iron, leading to siderite.


Magnesium orotate

Magnesium orotate, the magnesium salt of orotic acid, is a mineral supplement. It can be used in treating extracellular magnesium deficiency, as well as in mitigating magnesium depletion that inhibits the binding of adenosine triphosphate via orotic acid, which provides binding sites.


Thallous acetate

Thallous acetate is a salt of thallium and acetate with the chemical formula TlCH3COO. It is used in microbiology as a selective growth medium. It is poisonous.


Maricite

Maricite or "marićite" is a sodium iron phosphate mineral (NaFe2+PO4), that has two metal cations connected to a phosphate tetrahedron. It is structurally similar to the much more common mineral olivine. Maricite is brittle, usually colorless to gray, and has been found in nodules within shale beds often containing other minerals.
Maricite is most commonly known to be found in the Big Fish River area of the Yukon Territory, Canada, but it has also been found in Eastern Germany, as well as inside of various meteorites around the world. Maricite is named after Luka Maric (1899–1979) of Croatia, the longtime head of the mineralogy and petrography departments at the University of Zagreb.
Maricite is a sodium iron phosphate from the extremely diverse phosphate mineral group. In 1977 maricite was discovered in the Big Fish River area, Yukon Territory, Canada (Fleischer, Chao, and Mandarino, 1979). This is an important geologic location that has provided the discovery of several new phosphate minerals. Maricite is recognized for its possible use in sodium ion battery research as well as its role as a reaction product inside of fossil-fired electrical power generating station boilers which experience corrosion (Bridson, "et al.", 1997; Ong, "et al.", 2011).
Composition.
Maricite is a member of the phosphate mineral group. Phosphate minerals have one or more metal cations bonded to the phosphate anion PO4. (Hawthorne, F.C., 1998). In maricite the metals bonded to PO4 are sodium and iron (Sturman, "et al.", 1977). The empirical formula for maricite is NaFePO4 and it has a molar mass of 173.81 g/mol (Yahia, "et al.", 2008; Tremaine, Xiao, 1999). The general formula for maricite is ABPO4, (Yahia, "et al.", 2008). The chemical composition of the mineral was originally determined by the group of Dr. Corlett from the Department of Geological Sciences at Queen’s University, Kingston, Ontario, using electron microprobe analysis, and found to be Na 0.91(Fe 0.89 Mn 0.07 Mg 0.03)P 1.02 O 4.00 (Sturman, "et al.", 1977) when normalized to four oxygen atoms. The weight percentages were determined using six different points on a thin section and averaging the percentages of each oxide in all of the samples. The results in weight percent average of oxides are as follows: Na2O 16.5%, MgO 0.8%, CaO 0.0%, MnO 3.1%, FeO 37.4%, P2O5 42.5%, with a total of 100.3%. When looking at these results, one may determine that the majority of the oxide weight composition is made of FeO with P2O5 making up almost the same weight percentage. There is a significant percentage of the Na2O oxide and an insignificant percentage of the CaO oxide (~0). It is clear from looking at the oxide content of the mineral that the main components are going to be sodium, iron, phosphorus, and oxygen. The oxide factor may be used to determine the weight percentages of the individual elements as follows, 1 sodium atom totaling ~13% of composition, 1 iron atom totaling ~32% of composition, 1 phosphorus atom totaling ~18% of composition, and 4 oxygen atoms totaling ~37% of composition (Sturman, "et al.", 1977).
Structure.
Maricite is an ionic double metal phosphate, with a space filling capacity of about 70% (Le Page, and Donnay, 1977). The structure of maricite contains a sodium cation enclosed by ten oxygen anions within 10 Å, in an irregular coordination. There is (2+2+2) type distorted tetrahedron around the iron (Bridson, "et al.", 1997). The Å distances between iron and oxygen are between 2.33 and 2.93. The phosphate tetrahedron is almost regular, with 2 short bonds and 2 longer bonds (Bridson, "et al.", 1997). The iron atom has four surrounding oxygen atoms giving it tetrahedral coordination. Half of the oxygen atoms are coordinated with two sodium atoms, two iron atoms, and one phosphorus atom while the other half are coordinated with three sodium atoms, one iron atom and one phosphorus atom (Bridson, "et al.", 1997). The structure of maricite has been compared to the structure of olivine, (Lee, "et al.", 2011). The structures of the two minerals are similar because they both contain PO4 in their atomic make-up (Moreau, "et al.", 2010). However, the M1 and M2 sites for LiFePO4 and NaFePO4 have reverse occupancies making their structures different (Lee, "et al.", 2011). In olivine, the M1 site holds the alkali metal while the M2 site holds the transition metal, whereas in maricite, the M1 site holds the transition metal and the M2 site holds the alkali metal (Ong, "et al.", 2011).
Physical properties.
Maricite (NaFePO4), is found in elongated grains up to 15 cm long in the [100] direction. The grains are radial to sub parallel in structure. Maricite is usually colorless to gray, but is sometimes a pale brown color and it has a white streak. It has a vitreous luster due to its low values of refractive indices, α = 1.676 β = 1.695 γ = 1.698, and its opacity is transparent to translucent (Fleisher, "et al.", 1979). Maricite has no cleavage or pleochroism, and it does not fluoresce in UV light. Maricite has a hardness of 4-4.5 and a density of 3.64. The mineral is brittle, with an uneven splintery fracture. It is a member of the orthorhombic crystal class and the biaxial negative optical class and has a 2V calculation of 43°. The "Hermann-Mauguin notation" symbol is 2/m 2/m 2/m, and it is in the Pmnb space group. Yvon Le Page and Gabrielle Donnay determined that the cell dimensions are a 6.864(2), b 8.994(2), and c 5.049(1). J. A. Mandarino determined the d-spacings using "x-ray powder diffraction" and "Bragg’s law" to be 2.574 at an intensity of 100, 2.729 at an intensity of 90, 2.707 at an intensity of 80, 1.853 at an intensity of 60, 3.705 at an intensity of 40, 2.525 at an intensity of 30, and 1.881 also at an intensity of 30 (Fleisher, "et al.", 1979; Sturman, "et al.", 1977).
Geologic occurrence.
Maricite was first discovered in the Big Fish River area near the eastern border of the Yukon Territory around Latitude 68° 30’ N and Longitude 136° 30’ W. This area is a kulanite-baricite-peniksite type locality composed mostly of bedded shales and sideritic limestones. Maricite has been found in nodules up to 15 cm long within the shale beds. Some of the nodules contained only one mineral, while others contained several different minerals. Very few of the nodules consisted of only maricite. Most of the samples which contained maricite also had quartz, ludlamite, vivianite, pyrite and/or wolfeite. When samples which appeared to only contain maricite were examined closely in a thin section, there were small inclusions of ludlamite, quartz, and vivianite present along the fractures (Sturman, "et al.", 1977). The other location which formations of maricite have been found is Saxony, Germany (Thomas, R. and Webster J.D., 2000). Both this location and the Big Fish River Canada location are situated just north of convergent plate boundaries. Both areas consist of mountains and hills which are made of metamorphic and igneous rocks (Thomas, R. and Webster J.D., 2000; Sturman, "et al.", 1977). Maricite has also been discovered in meteorites found in Eastern Antarctica, Uttar Pradesh, India and Avannaa, Greenland (Johnson, "et al.", 2001; Kracher, "et al.", 1977; Partridge, "et al.", 1990).
History.
Maricite was named by Darko Sturman and Joseph Mandarino in honor of Luka Maric. Maric was the longtime head of the department of mineralogy and petrography at the University of Zagreb in Croatia. The name Maricite was approved in 1977 by the commission on new minerals and mineral names. It is unclear exactly why the mineral was named in honor of Maric, but he did author several geology books including one entitled Magmatiti u Uzhem Podruchju Rudnika Bor u Istochnoj Srbiji, which is Croatian for Magmatites in the Narrower Ore Deposit Region of the Bor Mine (Sturman, "et al.", 1977).


Tetraethylammonium bromide

Tetraethylammonium bromide (TEAB) is a quaternary ammonium compound with the chemical formula C8H20N+Br−, often written as "Et4N+Br−" in the chemical literature. It has been used as the source of tetraethylammonium ions in pharmacological and physiological studies, but is also used in organic chemical synthesis.
Chemistry.
Synthesis.
TEAB is commercially available, but can be prepared by the reaction between tetraethylammonium hydroxide and hydrobromic acid:
Evaporation of the water and recrystallization from acetonitrile yields a crystalline sample of TEAB.
Structure.
The crystal structure of TEAB has been determined and found to exhibit a distorted tetrahedral symmetry with respect to the geometry of the C atoms around the central N.
Synthetic applications.
Examples include:
Biology.
In common with tetraethylammonium chloride and tetraethylammonium iodide, TEAB has been used as a source of tetraethylammonium ions for numerous clinical and pharmacological studies, which are covered in more detail under the entry for tetraethylammonium. Briefly, TEAB has been explored clinically for its ganglionic blocking properties, although it is now essentially obsolete as a drug, and it is still used in physiological research for its ability to block K+ channels in various tissues.
Toxicity.
The toxicity of TEAB is primarily due to the tetraethylammonium ion, which has been studied extensively. The acute toxicity of TEAB is comparable to that of tetraethylammonium chloride and tetraethylammonium iodide. These data, taken from a study by Randall and co-workers, are provided for comparative purposes; additional details may be found in the entry for Tetraethylammonium.
LD50 for mouse: 38 mg/kg, i.v.; 60 mg/kg, i.p.; >2000 mg/kg, p.o.


Chitina Tin Shop

The Chitina Tin Shop, also known as Fred's Place and Schaupp's, is a historic retail building on Main Street in Chitina, Alaska. It is a wood frame structure, two stories in height, with a flat-topped false front in front of a gable roof. The building is wide and deep. It was built in 1912 by Fred Schaupp, during Chitina's building boom following the arrival of the Copper River and Northwestern Railway. The building is one of only a few surviving tin shops (essentially a metalworking facility) in the state. The first floor was occupied by the workshop, while living quarters were above. Following the closing of the railroad in 1938, the building has seen a variety of other uses. The building has been restored, and now houses an art gallery.
The building was listed on the National Register of Historic Places in 1979.


Isotopes of neutronium


Paratungstate

In chemistry, paratungstate refers to the anion with the formula [W12O42]12- and salts derived from this anion. The term also refers to protonated derivatives of this anion, including [H2W12O42]10-. Ammonium paratungstate (or APT), (NH4)10[H2W12O42] is a key intermediate in the purification of tungsten from its ores.
The salt (NH4)10(W12O42)·4H2O has been characterized by X-ray crystallography.
The unprotonated anion [W12O42]12- has C2h symmetry.


Sodium arsenite

Sodium arsenite usually refers to the inorganic compound with the formula NaAsO2. Also called sodium "meta"-arsenite, it is the sodium salt of arsenous acid. Sodium "ortho"-arsenite is Na3AsO3. The compounds are colourless solids.
Synthesis and structure.
A mixture of sodium "meta"-arsenite and sodium "ortho"-arsenite is produced by treating arsenic trioxide with sodium carbonate or sodium hydroxide. Sodium arsenite is amorphous, typically being obtained as a powder or as a glassy mass. The compound consists of the polymer [AsO2] associated with sodium cations, Na+. The polymer backbone has the connectivity -O-As(O−)-.
Health Effects.
Sodium arsenite can be inhaled or absorbed through the skin. Along with its known carcinogenic and teratogenic effects, contact with the substance can yield symptoms such as skin irritation, burns, itching, thickened skin, rash, loss of pigment, poor appetite, a metallic or garlic taste, stomach pain, nausea, vomiting, diarrhea, convulsions, decreased blood pressure, and headache. Severe acute poisoning may lead to nervous system damage resulting in weakness, poor coordination, or “pins and needles” sensations, eventual paralysis, and death.
Application.
It is primarily used as a pesticide, but has other uses such as hide preservative, antiseptic, dyeing, and soaps.
Sodium arsenite is an appropriate chemical stressor to induce the production of heat shock proteins, and the formation of cytoplasmic stress granules.
Sodium arsenite can be used as a reducing agent in organic chemistry, as it is able to reduce a trihaloalkane to a dihaloalkane:
Safety.
The LD50 (oral, mouse) is 40 mg/kg.


Vanadium nitride

Vanadium nitride, VN, is a chemical compound of vanadium and nitrogen.
Vanadium nitride is formed during the nitriding of steel and increases wear resistance. Another phase, V2N, also referred to as vanadium nitride, can be formed along with VN during nitriding. VN has a cubic, rock-salt structure. There is also a low-temperature form, which contains V4 clusters.
The low-temperature phase results from a dynamic instability, when the energy of vibrational modes in the high-temperature NaCl-structure phase, are reduced below zero.
It is a strong-coupled superconductor. Nanocrystalline vanadium nitride has been claimed to have potential for use in supercapacitors. The properties of vanadium nitride depend sensitively on the stoichiometry of the material.


Molybdenum fluoride

Molybdenum fluoride can refer to


Niobium pentoxide

Niobium pentoxide is the inorganic compound with the formula Nb2O5. It is a colorless insoluble solid that is fairly unreactive. It is the main precursor to all materials made of niobium, the dominant application being alloys, but other specialized applications include capacitors, lithium niobate, and optical glasses.
Structure.
It has many polymorphic forms all based largely on octahedrally coordinated niobium atoms. The polymorphs are identified with a variety of prefixes. The form most commonly encountered is monoclinic H-Nb2O5 which has a complex structure, with a unit cell containing 28 niobium atoms and 70 oxygen, where 27 of the niobium atoms are octahedrally coordinated and one tetrahedrally. There is an uncharacterised solid hydrate, Nb2O5."n"H2O, the so-called niobic acid (previously called columbic acid), which can be prepared by hydrolysis of a basic solution of niobium pentachloride or Nb2O5 dissolved in HF.
Molten niobium pentoxide has lower mean coordination numbers than the crystalline forms, with a structure comprising mostly NbO5 and NbO6 polyhedra.
Production.
Hydrolysis.
Nb2O5 is prepared by hydrolysis of alkali-metal niobates, alkoxides or fluoride using base. Such ostensibly simple procedures afford hydrated oxides that can then be calcined. Pure Nb2O5 can also be prepared by hydrolysis of NbCl5:
A method of production via sol-gel techniques has been reported hydrolysing niobium alkoxides in the presence of acetic acid, followed by calcination of the gels to produce the orthorhombic form, T-Nb2O5.
Oxidation.
Given that Nb2O5 is the most common and robust compound of niobium, many methods, both practical and esoteric, exist for its formation. The oxide for example, arises when niobium metal is oxidised in air. The oxidation of niobium dioxide, NbO2 in air forms the polymorph, L-Nb2O5.
Nano-sized niobium pentoxide particles have been synthesized by LiH reduction of NbCl5, followed by aerial oxidation as part of a synthesis of nano structured niobates.
Reactions.
Nb2O5 is attacked by HF and dissolves in fused alkali.
Reduction to the metal.
The conversion of Nb2O5 is the main route for the industrial production of niobium metal. In the 1980s, about 15,000,000 kg of Nb2O5 were consumed annually for reduction to the metal. The main method is reduction of this oxide with aluminium:
An alternative but less practiced route involves carbothermal reduction, which proceeds via reduction with carbon and forms the basis of the two stage Balke process:
Conversion to halides.
Many methods are known for conversion of Nb2O5 to the halides. The main problem is incomplete reaction to give the oxyhalides. In the laboratory, the conversion can be effected with thionyl chloride:
Nb2O5 reacts with CCl4 to give niobium oxychloride NbOCl3.
Conversion to niobates.
Treating Nb2O5 with aqueous NaOH at 200 °C can give crystalline sodium niobate, NaNbO3 whereas the reaction with KOH may yield soluble Lindqvist-type hexaniobates, . Lithium niobates such as LiNbO3 and Li3NbO4 can be prepared by reaction lithium carbonate and Nb2O5.
Conversion to reduced niobium oxides.
High temperature reduction with H2 gives NbO2:
Niobium monooxide arises from a comproportionation using an arc-furnace:
The burgundy-coloured niobium(III) oxide, one of the first superconducting oxides, can be prepared again by an comproportionation:
Uses.
Niobium pentoxide is used mainly in the production of niobium metal, but specialized applications exist for lithium niobate and as a component of optical glass.
Thin films of Nb2O5 form the dielectric layers in solid electrolyte capacitors.


Chloroacetaldehyde

Chloroacetaldehyde is an organic compound with the formula ClCH2CHO. Like some related compounds, it is highly electrophilic reagent and a potentially dangerous alkylating agent. The compound is not normally encountered in the anhydrous form, but rather as the hemiacetal (ClCH2CH(OH))2O.
Chloroacetaldehyde is a useful intermediate in the synthesis of 2-aminothiazole including the pharmaceuticals altizide, polythiazide, brotizolam and ciclotizolam. Another use is to facilitate bark removal from tree trunks.
Synthesis and reactions.
Hydrated chloroacetaldehyde is produced by the chlorination of aqueous vinyl chloride:
It can also be prepared from vinyl acetate or by careful chlorination of acetaldehyde. The related bromoacetaldehyde is prepared via bromination of vinyl acetate. It also rapidly forms an acetals in the presence of alcohols.
Being bifunctional, chloroacetaldehyde is a versatile precursor to many heterocyclic compounds. It condenses with thiourea derivatives to give aminothiazoles. This reaction was important as a precursor to sulfathiazole, one of the first sulfa drugs.
Anhydrous.
Water free chloroacetaldehyde is prepared from the hydrate by azeotropic distillation with chloroform, toluene or carbon tetrachloride. Anhydrous chloroacetaldehyde reversibly converts to polyacetals. Less reactive chloroacetaldehyde derivatives might be used instead to obtain chloroacetaldehyde or bypass its intermediate formation completely: e.g. chloroacetaldehyde dimethyl acetal (2-chloro-1,1-dimethoxyethane) hydrolyzes in acidic conditions to give chloroacetaldehyde, which may then quickly react with the other reagents instead of polymerizing.
Hemihydrate.
Hemihydrate is formed as below. It has a melting point of 43–50°C, boiling point of 85.5 °C.
Environmental aspects.
Chloroacetaldehyde is a metabolite in the degradation of 1,2-dichloroethane, which initially converts to chloroethanol. This metabolic pathway is topical because 1,2-dichloroethane is produced on a large as a precursor to vinyl chloride.
Safety.
Chloroacetaldehyde is corrosive to mucous membranes. It irritates eyes, skin and respiratory tract.
Based on data collected from human studies in 1962, exposures to 45 ppm of chloroacetaldehyde were found to be disagreeable and caused conjunctival irritation to the subjects. The Occupational Safety and Health Administration established a permissible exposure limit at a ceiling of 1 ppm (3 mg/m3) for exposures to chloroacetaldehyde.


Strip algebra

Strip Algebra is a set of elements and operators for the description of carbon nanotube structures, considered as a subgroup of polyhedra, and more precisely, of polyhedra with vertices formed by three edges. This restriction is imposed on the polyhedra because carbon nanotubes are formed of sp2 carbon atoms. Strip Algebra was developed initially
for the determination of the structure connecting two arbitrary nanotubes, but has also been extended to the connection of three identical nanotubes
Background.
Graphitic systems are molecules and crystals formed of carbon atoms in sp2 hybridization. Thus, the atoms are arranged on a hexagonal grid. Graphite, nanotubes, and fullerenes are examples of graphitic systems. All of them share the property that each atom is bonded to three others (3-valent).
The relation between the number of vertices, edges and faces of any finite polyhedron is given by Euler's polyhedron formula:
where "e", "f" and "v" are the number of edges, faces and vertices, respectively, and "g" is the genus of the polyhedron, i.e., the number of "holes" in the surface. For example, a sphere is a surface of genus 0, while a torus is of genus 1.
Nomenclature.
A substrip is identified by a pair of natural numbers measuring the position of the last ring in parentheses, together with the turns induced by the defect ring. The number of edges of the defect can be extracted from these.
Elements.
A Strip is defined as a set of consecutive rings, that is able to be joined with others, by sharing a side of the first or last ring.
Numerous complex structures can be formed with strips. As said before, strips have both at the beginning and at the end two connections. With strips only, can be formed two of them.
Operators.
Given the definition of a strip, a set of operations may be defined. These are necessary to find out the combined result of a set of contiguous strips.