Organic Chemestry

Organic chemistryis a chemistrysubdiscipline involving the scientificstudy of the structure, properties, and reactions of organic compoundsand organic materials, i.e., matter in its various forms that contain carbon atoms. [ 1 ]Study of structure includes using spectroscopy (e.g., NMR), mass spectrometry, and other physical and chemical methods to determine the chemical compositionand constitutionof organic compounds and materials. Study of properties includes both physical propertiesand chemical properties, and uses similar methods as well as methods to evaluate chemical reactivity, with the aim to understand the behavior of the organic matter in its pure form (when possible), but also in solutions, mixtures, and fabricated forms. The study of organic reactionsincludes probing their scope through use in preparation of target compounds (e.g., natural products, drugs, polymers, etc.) by chemical synthesis, as well as the focused study of the reactivitiesof individual organic molecules, both in the laboratory and via theoretical ( in silico) study. The range of chemicals studied in organic chemistry include hydrocarbons, compounds containing only carbonand hydrogen, as well as myriad compositions based always on carbon, but also containing other elements, [ 1 ] [ 2 ] [ 3 ]especially: *.oxygen, nitrogen, sulfur, phosphorus (these, included in many organic chemicals in biology) and the radiostableof the halogens. In the modern era, the range extends further into the periodic table, with main group elements, including: *.Group 1 and 2 organometallic compounds, i.e., involving alkali(e.g., lithium, sodium, and potassium) or alkaline earth metals(e.g., magnesium), or *. metalloids(e.g., boron and silicon) or other metals(e.g., aluminum and tin). In addition, much modern research focuses on organic chemistry involving further organometallics, including the lanthanides, but especially the: *. transition metals(e.g., zinc, copper, palladium, nickel, cobalt, titanium, chromium, etc.). Line-angle representation Ball-and-stick representation Space-filling representation Three representations of an organic compound, 5α-Dihydroprogesterone(5α-DHP), a steroid hormone. For molecules showing color, the carbon atoms are in black, hydrogens in gray, and oxygens in red. In the line angle representation, carbon atoms are implied at every terminus of a line and vertex of multiple lines, and hydrogen atoms are implied to fill the remaining needed valences (up to 4). Finally, organic compoundsform the basis of all earthly lifeand constitute a significant part of human endeavors in chemistry. The bonding patterns open to carbon, with its valence of four—formal single, double, and triple bonds, as well as various structures with delocalized electrons—make the array of organic compounds structurally diverse, and their range of applications enormous. They either form the basis of, or are important constituents of, many commercial products including pharmaceuticals; petrochemicalsand products made from them (including lubricants, solvents, etc.); plastics; fuelsand explosives; etc. As indicated, the study of organic chemistry overlaps with organometallic chemistryand biochemistry, but also with medicinal chemistry, polymer chemistry, as well as many aspects of materials science. [ 1 ] Periodic tableof elements of interest in organic chemistry. The table illustrates all elementsof current interest in modern organic and organometallicchemistry, indicating main group elementsin orange, and transition metalsand lanthanides(Lan) in grey.

Inorganic Chemestry

Inorganic chemistryis the study of the synthesis and behavior of inorganic and organometallic compounds. This field covers all chemical compoundsexcept the myriad organic compounds(carbon based compounds, usually containing C-H bonds), which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, and there is much overlap, most importantly in the sub-discipline of organometallic chemistry. It has applications in every aspect of the chemical industry–including catalysis, materials science, pigments, surfactants, coatings, medicine, fuel, and agriculture. [ 1 ] Key concepts The structure of the ionic framework in potassium oxide, K2O Many inorganic compoundsare ionic compounds, consisting of cationsand anionsjoined by ionic bonding. Examples of salts (which are ionic compounds) are magnesium chlorideMgCl2, which consists of magnesiumcations Mg2+and chlorideanions Cl−; or sodium oxideNa2O, which consists of sodiumcations Na+and oxideanions O2−. In any salt, the proportions of the ions are such that the electric charges cancel out, so that the bulk compound is electrically neutral. The ions are described by their oxidation stateand their ease of formation can be inferred from the ionization potential(for cations) or from the electron affinity(anions) of the parent elements. Important classes of inorganic salts are the oxides, the carbonates, the sulfatesand the halides. Many inorganic compounds are characterized by high melting points. Inorganic salts typically are poor conductorsin the solid state. Other important features include their solubility in water(see: solubility chart) and ease of crystallization. Where some salts (e.g., NaCl) are very soluble in water, others (e.g., SiO 2) are not. The simplest inorganic reactionis double displacementwhen in mixing of two salts the ions are swapped without a change in oxidation state. In redox reactionsone reactant, theoxidant, lowers its oxidation state and another reactant, thereductant, has its oxidation state increased. The net result is an exchange of electrons. Electron exchange can occur indirectly as well, e.g., in batteries, a key concept in electrochemistry. When one reactant contains hydrogen atoms, a reaction can take place by exchanging protons in acid-base chemistry. In a more general definition, an acid can be any chemical species capable of binding to electron pairs is called a Lewis acid; conversely any molecule that tends to donate an electron pair is referred to as a Lewis base. As a refinement of acid-base interactions, the HSAB theorytakes into account polarizability and size of ions. Inorganic compounds are found in nature as minerals. Soil may contain iron sulfide as pyriteor calcium sulfate as gypsum. Inorganic compounds are also found multitasking as biomolecules: as electrolytes ( sodium chloride), in energy storage ( ATP) or in construction (the polyphosphatebackbone in DNA). The first important man-made inorganic compound was ammonium nitratefor soil fertilization through the Haber process. Inorganic compounds are synthesized for use as catalystssuch as vanadium(V) oxideand titanium(III) chloride, or as reagentsin organic chemistrysuch as lithium aluminium hydride. Subdivisions of inorganic chemistry are organometallic chemistry, cluster chemistryand bioinorganic chemistry. These fields are active areas of research in inorganic chemistry, aimed toward new catalysts, superconductors, and therapies.

Optics

Opticsis the branch of physicswhich involves the behaviour and properties of light, including its interactions with matterand the construction of instrumentsthat use or detectit. [ 1 ]Optics usually describes the behaviour of visible, ultraviolet, and infraredlight. Because light is an electromagnetic wave, other forms of electromagnetic radiationsuch as X-rays, microwaves, and radio wavesexhibit similar properties. [ 1 ] Most optical phenomena can be accounted for using the classical electromagneticdescription of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of raysthat travel in straight lines and bend when they pass through or reflect from surfaces. Physical opticsis a more comprehensive model of light, which includes waveeffects such as diffractionand interferencethat cannot be accounted for in geometric optics. Historically, the ray-based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that light waves were in fact electromagnetic radiation. Some phenomena depend on the fact that light has both wave-like and particle-like properties. Explanation of these effects requires quantum mechanics. When considering light's particle-like properties, the light is modelled as a collection of particles called " photons". Quantum opticsdeals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineeringfields, photography, and medicine(particularly ophthalmologyand optometry). Practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics. History Main article: History of optics See also: Timeline of electromagnetism and classical optics The Nimrud lens Optics began with the development of lenses by the ancient Egyptiansand Mesopotamians. The earliest known lenses, made from polished crystal, often quartz, date from as early as 700 BC for Assyrianlenses such as the Layard/ Nimrud lens. [ 2 ]The ancient RomansandGreeks filled glass ...philosophers, and the development of geometrical opticsin the Greco-Roman world. The wordopticscomes from the ancient Greekwordὀπτική, meaning "appearance, look". [ 3 ] Greek philosophyon optics broke down into two opposing theories on how vision worked, the " intromission theory" and the "emission theory". [ 4 ]The intro-mission approach saw vision as coming from objects casting off copies of themselves (called eidola) that were captured by the eye. With many propagators including Democritus, Epicurus, Aristotleand their followers, this theory seems to have some contact with modern theories of what vision really is, but it remained only speculation lacking any experimental foundation. Platofirst articulated the emission theory, the idea that visual perceptionis accomplished by rays emitted by the eyes.

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papilliedema

Papilledema(orpapilloedema) is optic discswelling that is caused by increased intracranial pressure. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare. Papilledema is mostly seen as a symptom resulting from another pathophysiological process. In intracranial hypertension, papilledema most commonly occurs bilaterally. When papilledema is found on fundoscopy, further evaluation is warranted as vision loss can result if the underlying condition is not treated. Further evaluation with a CT or MRI of the brain and/or spine is usually performed. Unilateral papilledema can suggest orbital pathology, such as an optic nerve glioma. Signs and symptoms Fundal photograph showing less severe papilledema Papilledema may be asymptomatic or present with headache in the early stages. However it may progress to enlargement of the blind spot, blurring of vision, visual obscurations (inability to see in a particular part of the visual field for a period of time) and ultimately total loss of vision may occur. The signs of papilledema that are seen using an ophthalmoscopeinclude: *.venous engorgement (usually the first signs) *.loss of venous pulsation *.hemorrhages over and / or adjacent to the optic disc *.blurring of optic margins *.elevation of optic disc *.Paton's lines = radial retinal lines cascading from the optic disc On visual fieldexamination, the physician may elicit an enlarged blind spot; the visual acuity may remain relatively intact until papilledema is severe or prolonged. Diagnosis Checking the eyesfor signsof papilledema should be carried out whenever there is a clinical suspicion of raised intracranial pressure, and is recommended in newly onset headaches. This may be done by ophthalmoscopyor fundus photography, and possibly slit lampexamination. Causes Raised intracranial pressureas a result of one or more of the following: *. Brain tumor, Pseudotumor Cerebri(also known as Idiopathic Intracranial Hypertension), Cerebral venous sinus thrombosisor Intracerebral hemorrhage *. Respiratory failure [ 1 ] *. Hypotonia *. Isotretinoin, which is a powerful derivative of Vitamin A, rarely causes papilledema. *. Hypervitaminosis A, in some people who take megadoses of nutritional supplements and vitamins. *. Hyperammonemia, elevated level of ammonia in blood (including cerebral edema/intracranial pressure) *. Guillain-Barré syndrome, due to elevated proteinlevels *. Foster Kennedy syndrome(FKS) *. Chiari Malformation *. Tumorsof the frontal lobe *. Acute Mountain Sicknessand High-altitude cerebral edema *. Lyme disease(Lyme meningitisspecifically, when the bacterial infection is in the central nervous system, causing increased intracranial pressure). *. Malignant Hypertension *. Medulloblastoma *.Orbital *. Glaucoma: Central retinal vein occlusion, Cavernous sinus thrombosis *.Local lesion: Optic neuritis, Ischemic optic neuropathy, Methanol poisoning, infiltration of the discby Glioma, Sarcoidosisand Lymphoma *.Acute Lymphocytic leukemia(caused by infiltration of the retinal vessels by immature leukocytes) *.Long periods of weightlessness( microgravity) for males

platinum

Platinumis a chemical elementwith the chemical symbolPtand an atomic numberof 78. It is a dense, malleable, ductile, highly unreactive, precious, gray-white transition metal. Its name is derived from the Spanish termplatina, which is literally translated into "little silver". [ 1 ] [ 2 ] Platinum is a member of the platinum groupof elements and group 10of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarest elements in the Earth's crustwith an average abundance of approximately 5 μg/kg. It occurs in some nickeland copperores along with some nativedeposits, mostly in South Africa, which accounts for 80% of the world production. Because of its scarcity in the earth's crust, only a few hundred tonnesare produced annually, and is therefore highly valuable and is a major precious metal commodity. Platinum is the least reactive metal. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sandsof various rivers, it was first used by pre-ColumbianSouth American natives to produce artifacts. It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloapublished a report on a new metal of Colombianorigin in 1748 that it became investigated by scientists. Platinum is used in catalytic converters, laboratory equipment, electricalcontacts and electrodes, platinum resistance thermometers, dentistryequipment, and jewellery. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals. [ 3 ]Compounds containing platinum, most notably cisplatin, are applied in chemotherapyagainst certain types of cancer. [ 4 ] Characteristics Physical Pure platinum is a lustrous, ductile, and malleable, silver-white metal. [ 5 ]Platinum is more ductilethan gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold. [ 6 ] [ 7 ]Pure platinum is slightly harder than pure iron.[ citation needed]The metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. It does not oxidize at any temperature, although it is corroded by halogens, cyanides, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloricand nitric acid, but dissolves in hot aqua regiato form chloroplatinic acid, H2PtCl6.Blog Directory at OnToplist.comBlog Directory | Submit to Directories and Promote your BlogsBlog Directory at OnToplist.com

Diamond

In mineralogy,diamond(from the ancient Greekαδάμας –adámas"unbreakable") is a metastable allotrope of carbon, where the carbon atomsare arranged in a variation of the face-centered cubiccrystal structure called a diamond lattice. Diamond is less stablethan graphite, but the conversion rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bondingbetween its atoms. In particular, diamond has the highest hardnessand thermal conductivityof any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knivesand diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boronand nitrogen. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown ( lattice defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion(ability to disperse light of different colors). Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth's surface through deep volcanic eruptionsby a magma, which cools into igneous rocksknown as kimberlitesand lamproites. Diamonds can also be produced synthetically in a high-pressure high-temperatureprocess which approximately simulates the conditions in the Earth's mantle. An alternative, and completely different growth technique is chemical vapor deposition(CVD). Several non-diamond materials, which include cubic zirconiaand silicon carbideand are often called diamond simulants, resemble diamond in appearance and many properties. Special gemologicaltechniques have been developed to distinguish natural and synthetic diamondsand diamond simulants.Blog Directory at OnToplist.com

ELECTRO CONDUCTIVE THREAD

On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research. While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity.Credit: Illustration by Tanyia Johnson [Click to enlarge image] On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research. While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity. But a series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper, carrying up to four times as much current as a copper wire of the same mass. Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions -- air, argon, nitrogen and a vacuum -- to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Credit: Kono Lab/Rice University) That, said the researchers, makes nanotube-based cables an ideal platform for lightweight power transmission in systems where weight is a significant factor, like aerospace applications. The analysis led by Rice professors Junichiro Kono and Matteo Pasquali appeared online this week in the journalAdvanced Functional Materials. Just a year ago the journal Science reported that Pasquali's lab, in collaboration with scientists at the Dutch firm Teijin Aramid, created a very strong conductive fiber out of carbon nanotubes. Present-day transmission cables made of copper or aluminum are heavy because their low tensile strength requires steel-core reinforcement. Scientists working with nanoscale materials have long thought there's a better way to move electricity from here to there. Certain types of carbon nanotubes can carry far more electricity than copper. The ideal cable would be made of long metallic "armchair" nanotubes that would transmit current over great distances with negligible loss, but such a cable is not feasible because it's not yet possible to manufacture pure armchairs in bulk, Pasquali said. In the meantime, the Pasquali lab has created a method to spin fiber from a mix of nanotube types that still outperforms copper. The cable developed by Pasquali and Teijin Aramid is strong and flexible even though at 20 microns wide, it's thinner than a human hair. Pasquali turned to Kono and his colleagues, including lead author Xuan Wang, a postdoctoral researcher at Rice, to quantify the fiber's capabilities. Pasquali said there has been a disconnect between electrical engineers who study the current carrying capacity of conductors and materials scientists working on carbon nanotubes. "That has generated some confusion in the literature over the right comparisons to make," he said. "Jun and Xuan really got to the bottom of how to do these measurements well and compare apples to apples." The researchers analyzed the fiber's "current carrying capacity" (CCC), or ampacity, with a custom rig that allowed them to test it alongside metal cables of the same diameter.

CONDUCTIVE TEXTILE

Aconductive textileis a fabricwhich can conduct electricity. Conductive textiles can be made with metal strands woveninto the construction of the textile. There is also an interest in semiconducting textiles, made by impregnating normal textiles with carbon- or metal-based powders. [ 1 ] Conductive fibers consist of a non-conductive or less conductive substrate, which is then either coated or embedded with electrically conductive elements, often carbon, nickel, copper, gold, silver, or titanium. Substrates typically include cotton, polyester, nylon, and stainless steelto high performance fibers such as aramids and PBO. Straddling the worlds of textiles and wires, conductive fibers are sold either by weight or length, and measured in denieror AWG. Because of the rapid growth in the kinds of conductive fibers and the uses of these fibers, a trade association has been formed to increase awareness, utilization, and possibly standarize terminology. The association is Conductive Fiber Manufacturers Council. [ 2 ] Applications Uses for conductive fibers and textiles may include staticdissipation, EMI shielding, [ 3 ]signal and power transfer in low resistanceversions, and as a heating elementin higher resistance versions. Their benefits over solid or stranded metal wires come from conductive fibers' flexibility and ability to use them in existing textile and wire machinery (weaving, knitting, braiding, etc.) Another more recent use is in the production of 'Stun gun' or Taser proof clothing, where the conductive textile is used as a sort of Faraday shield in a layer of the garment in question. Conductive fabric can also be used to make electrodesfor EEGand other medical applications; [ 4 ]such electrodes were used in a commercially-available sleep-monitoring device made by former company Zeo, Inc.Highly conductive stainless steel fiber is available.

CNT CARBON NANOTUBE

Carbon nanotubes(CNTs) are allotropes of carbonwith a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, [ 1 ]significantly larger than for any other material. These cylindrical carbon moleculeshave unusual properties, which are valuable for nanotechnology, electronics, opticsand other fields of materials scienceand technology. In particular, owing to their extraordinary thermal conductivityand mechanical and electricalproperties, carbon nanotubes find applications as additives to various structural materials. For instance, nanotubes form a tiny portion of the material(s) in some (primarily carbon fiber) baseball bats, golf clubs, or car parts. [ 2 ] Nanotubes are members of the fullerenestructural family. Their name is derived from their long, hollow structure with the walls formed by one-atom-thick sheets of carbon, called graphene. These sheets are rolled at specific and discrete (" chiral") angles, and the combination of the rolling angle and radius decides the nanotube properties; for example, whether the individual nanotube shell is a metalor semiconductor. Nanotubes are categorized as single-walled nanotubes(SWNTs) and multi-walled nanotubes(MWNTs). Individual nanotubes naturally align themselves into "ropes" held together by van der Waals forces, more specifically, pi-stacking. Applied quantum chemistry, specifically, orbital hybridizationbest describes chemical bonding in nanotubes. The chemical bondingof nanotubes is composed entirely of sp 2 bonds, similar to those of graphite. These bonds, which are stronger than the sp 3 bondsfound in alkanesand diamond, provide nanotubes with their unique strength. Types of carbon nanotubes and related structures Terminology There is no consensus on some terms describing carbon nanotubes in scientific literature: both "-wall" and "-walled" are being used in combination with "single", "double", "triple" or "multi", and the letter C is often omitted in the abbreviation; for example, multi-walled carbon nanotube (MWNT) Most single-walled nanotubes (SWNT) have a diameter of close to 1 nanometer, with a tube length that can be many millions of times longer. The structure of a SWNT can be conceptualized by wrapping a one-atom-thick layer of graphite called graphene into a seamless cylinder. The way the graphene sheet is wrapped is represented by a pair of indices (n,m). The integersnandmdenote the number of unit vectorsalong two directions in the honeycomb crystal latticeof graphene. Ifm= 0, the nanotubes are called zigzag nanotubes, and ifn=m, the nanotubes are called armchair nanotubes. Otherwise, they are called chiral. The diameter of an ideal nanotube can be calculated from its (n,m) indices as follows wherea= 0.246 nm. SWNTs are an important variety of carbon nanotube because most of their properties change significantly with the (n,m) values, and this dependence is non-monotonic (see Kataura plot). In particular, their band gapcan vary from zero to about 2 eV and their electrical conductivity can show metallic or semiconducting behavior. Single-walled nanotubes are likely candidates for miniaturizing electronics. The most basic building block of these systems is the electric wire, and SWNTs with diameters of an order of a nanometer can be excellent conductors. [ 3 ] [ 4 ]One useful application of SWNTs is in the development of the first intermolecular field-effect transistors(FET). The first intermolecular logic gateusing SWCNT FETs was made in 2001. [ 5 ]A logic gate requires both a p-FET and an n-FET.

NICHROME

Nichromeis a non-magnetic alloyof nickel, chromium, and often iron, usually used as a resistance wire. History Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting pointof about 1,400 °C(2,550 °F). Due to its resistance to oxidationand stability at high temperatures, it is widely used in electric heating elements, such as in appliances and tools. Typically, nichrome is wound in coils to a certain electrical resistance, and current is passed through it to produce heat. Uses Nichrome is used in the explosivesand fireworksindustry as a bridgewirein electric ignition systems, such as electric matchesand model rocketigniters. Industrial and hobby hot-wire foam cuttersuse nichrome wire. Nichrome wire is commonly used in ceramicas an internal support structure to help some elements of claysculptures hold their shape while they are still soft. Nichrome wire is used for its ability to withstand the high temperatures that occur when clay work is fired in a kiln. Nichrome wire can be used as an alternative to platinumwire for flame testingby colouring the non-luminous part of a flame to detect cationssuch as sodium, potassium, copper, calcium etc. The alloytends to be expensive due to its high nickelcontent. Distributor pricing is typically indexed to commodity market prices for nickel. Other areas of usage include motorcycle silencers, in certain areas in the microbiological lab apparatus, and as the heating element of plastic extruders by the RepRap3D printing community. For heating, resistance wire must be stable in air when hot. Nichrome wire forms a protective layer of chromium oxide. [ 1 ] Nichrome may be also used as the coils of electronic cigarettes for vaping. Properties The properties of nichrome vary depending on its alloy. Figures given are representative of typical material and are accurate to expressed significant figures. Any variations are due to different percentages of nickel or chromium. Material propertyValueUnit Modulus of elasticity2.2 × 1011Pa Density8400kg/m3 Melting point1400 °C Electrical resistivity at room temperature(1.0—1.5) × 10−6Ω·m Specific heat450J/(kg· K) Thermal conductivity11.3W/(m·K) Thermal expansion14 × 10−6K−1 Standard ambient temperature and pressure used unless otherwise noted. Table 1: Resistance per inch (Ω), closed helix, 80/20 alloy. [ 2 ] Wire Gauge ( B&SNo. / AWG)Outside Diameter of Helix(inches) 3/45/81/23/81/47/323/165/321/83/321/161/32 140.4460.3650.2830.2020.1210.101 150.6380.5230.4080.2930.1780.1480.120 160.8950.7350.5750.4150.2550.2150.1750.135 171.321.080.8510.6170.3830.3250.2660.2080.150 181.891.561.220.8910.5590.4750.3920.3090.226 192.602.141.691.230.7790.6650.5510.4380.324 203.723.072.421.781.130.9670.8050.6440.482 214.533.582.631.681.451.210.9710.7330.496 224.983.672.362.031.701.371.05.719 237.025.183.342.882.421.961.511.05 237.025.183.342.882.421.961.511.05 244.694.053.412.782.141.60.865 256.875.945.024.103.172.251.32