Monosaccharides are carbohydrates, with the general formula Cn(H2O)n, that cannot be decomposed to a simpler carbohydrates by hydrolysis.
Depending on whether the molecule contains an aldehyde group (-CHO) or a ketone group (-CO-) monosaccharide can be a polyhydroxy aldehyde (aldose) or a polyhydroxy ketone (ketose). These aldehyde and ketone groups confer reduction properties on monosaccharides. They are also classified according to the number of carbon atoms they contain: trioses have three carbon atoms, tetroses four, pentoses five, hexoses six, heptoses seven, etc. These two systems of classification are often combined. For example, a six-carbon polyhydroxy aldehyde such as D-glucose is an aldohexose, whereas a six-carbon polyhydroxy ketone such as D-fructose is a ketohexose.
The notations D and L are used to describe the configurations of carbohydrates. In Fischer projections of monosaccharides, the carbonyl group is always placed on top (in the case of aldoses) or as close to the top as possible (in the case of ketoses). If the OH group attached to the bottom-most asymmetric carbon (the carbon that is second from the bottom) is on the right, then the compound is a D-sugar. If the OH group is on the left, then the compound is an L-sugar. Almost all sugars found in nature are D-sugars.
Monosaccharides can exist as either straight-chain or ring-shaped molecules. During the conversion from straight-chain form to cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a chiral center with two possible configurations (anomers), α and β. When the stereochemistry of the first carbon matches the stereochemistry of the last stereogenic center the sugar is the α-anomer when they are opposite the sugar is the β-anomer.
Nuclear reactor is an assembly of fissionable material (uranium-235 or plutonium-239) designed to produce a sustained and controllable chain reaction for the generation of electric power.
The essential components of a nuclear reactor are:
Osmium was discovered by Smithson Tennant (England) in 1803. The origin of the name comes from the Greek word osme meaning smell. It is hard fine black powder or hard, lustrous, blue-white metal. Unaffected by air, water and acids. Characteristic acrid, chlorine like odour due to tetroxide compound. Osmium tetroxide highly toxic. Osmium is obtained from the same ores as platinum. Used to tip gold pen points, instrument pivots, to make electric light filaments. Used for high temperature alloys and pressure bearings. Very hard and resists corrosion better than any other.
Paschen series are the series of lines in the spectrum of the hydrogen atom which corresponds to transitions between the state with principal quantum number n = 3 and successive higher states.
Picnometer is a special glass flask which is used for determining a relative density of liquids using the weight of a known volume. It usually has a glass faceted cork which is pierced in the centre like a thin capillary through which surplus of liquid runs out.
Redox potential is the potential of a reversible oxidation-reduction electrode measured with respect to a reference electrode, corrected to the hydrogen electrode, in a given electrolyte.
Rhenium was discovered by Walter Noddack, Ida Tacke and Otto Berg (Germany) in 1925. The origin of the name comes from the Latin word Rhenus meaning river Rhine. It is rare and costly, dense, silvery-white metal. Tarnishes in moist air. Resists corrosion and oxidation. Dissolves in nitric and sulfuric acids. Has a very high melting point. Rhenium is found in small amounts in gadolinite and molybdenite. Mixed with tungsten or platinum to make filaments for mass spectrographs. Its main value is as a trace alloying agent for hardening metal components that are subjected to continuous frictional forces.
Rhombohedral (or trigonal) lattice has one lattice point at the each corner of the unit cell. It has unit cell vectors a=b=c and interaxial angles α=β=γ≠90°.
Sacrificial protection is the protection of iron or steel against corrosion by using a more reactive metal. Pieces of zinc or magnesium alloy are attached to pump bodies and pipes. The protected metal becomes the cathode and does not corrode. The anode corrodes, thereby providing the desired sacrificial protection. These items are known as sacrificial anodes and "attract" the corrosion to them rather than the iron/steel. The sacrificial anodes must be replaced periodically as they corrode.
The iron pipe will be connected to a more reactive metal such as magnesium through cooper wires, the magnesium will donate its electrons to the iron preventing it from rusting. Iron which is oxidises will immediately be reduced back to iron.
Simple or primitive cubic lattice (sc or cubic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a = b = c and interaxial angels α=β=γ=90°.
The simplest crystal structures are those in which there is only a single atom at each lattice point. In the sc structures the spheres fill 52 % of the volume. The number of atoms in a unit cell is one (8×1/8 = 1). This is only one metal (α-polonium) that have the sc lattice.
Generalic, Eni. "High fructose corn syrup." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table