Double dash

Practically all liquid cells with reversible interfacial equilibria examined can be considered as liquid galvanic cells of the Nernst, Haber, or intermediate type [3]. Usually, a dashed vertical bar ( ) is used to represent the junction between liquids. A double dashed vertical bar ( ) represents a liquid junction in which the diffusion potential has been assumed to be eliminated. 

Figure 1.8. The top left sphere shows the positive (shaded) and negative (unshaded) regions for the real-valued function 2 - The top right sphere shows the pure real (solid) and pure imaginary (dashed) meridian for the function 72,2- The bottom picture shows the zero points (double-dashed) as well as the pure real (soUd) and pure imaginary (dashed) meridians of 12,1 There are colored versions of these pictures available on the internet. See, for instance, [Re].

Ethylene (C2H4) is an organic compound with a double bond. When we draw a Lewis structure for ethylene, the only way to show both carbon atoms with octets is to draw them sharing two pairs of electrons. The following examples show organic compounds with double bonds. In each case, two atoms share four electrons (two pairs) to give them octets. A double dash (=) symbolizes a double bond. 

A single vertical bar ( ) should be used to represent a phase boundary, a dashed vertical bar ( ) to represent a junction between miscible liquids, and double, dashed vertical bars ( ) to represent a liquid junction, in which the liquid junction potential has been assumed to be eliminated (see also -> concentration cells). 

Fig. 1. The reductive pentose phosphate cycle (RPP). The solid lines indicate reactions of the RPP cycle. The number of lines per arrow indicates the number of times each reaction occurs for one complete turn of the cycle in which three molecules of COj are converted to one molecule of G3P. Each reaction of the cycle occurs at least once. The double dashed lines indicate the principal reactions removing intermediate compounds of the cycle for biosynthesis. Abbreviations RuBP, ribulose 1,5-bis-phosphate PGA, 3-phosphoglycerate DPGA, 1,3-diphosphoglycerate, FBP, fructose 1,6-bisphos-phate F6P, fructose 6-phosphate SBP, sedoheptulose 1,7-bisphosphate S7P, sedoheptulose 7-phosphate Xu5P, xylulose 5-phosphate R5P, ribose 5-phosphate Ru5P, ribulose 5-phosphate TPP, thiamine pyrophosphate. From Ref. 1.

If now we use a single dash to denote any sample other than the last and a double dash to denote the last (that of highest molecular weight) and we compare the behaviour of the two samples at the same volume fraction q> we have... 

Carbon atoms readily form covalent bonds with other carbon atoms and with atoms of other nonmetals, especially hydrogen, nitrogen, oxygen, phosphorus, sulfur, and the halogens. Carbon atoms form these bonds by sharing pairs of electrons with atoms of other elements. When two atoms share two electrons, the bond is called a single bond (symbolized in a structural formula by a single dash - ). When four electrons are shared, the bond is called a double bond (symbolized by a double dash = ). When six electrons are shared, the bond is called a triple bond (symbolized by a triple dash <=> ). A carbon atom will... 

Figure A3.2 The structure of an alpha-helix. Oxygen atoms are shown in red and nitrogens in blue. In this spiral arrangement of the polypeptide chain, the C=0 and N—H bonds are approximately parallel to the helix axis and able to form multiple H-bonds, shown here as double dashed lines.

For positions 23-36, a double stripe or double dash is added. 

NOTE Throughout this chapter recommendations by the International Union of Pure and Applied Chemistry (lUPAC) [1, 2] for representing electrochemical cells will be followed stating that a single vertical bar (I) should be used to represent a phase boundary, a dashed vertical bar ( ) to represent a junction between miscible liquids, and a double dashed bar ( ) to represent a liquid junction, in which die liquid junction (potential) is assumed to be eliminated. The subscripts account for die following (s), solid (1), liquid (aq), aqueous and (Hg), amalgam. A slash (/) is used for cases where both forms of the redox couple are assumed to be in solution. 

In most bcc metals and alloys, the dislocation loops formed under irradiation consist predominantly of loops with Burgers vector b = all < 111 > (with 111 or 110 habit plane). By contrast, in ferritic alloys, loops with b = a <100>, mostly on 100 planes are also found, which sometimes dominate the microstmcture. An example of such a loop microstmcmre is shown in Fig. 9.1. The a <100> loops are seen edge on with double dash contrast, while a few dl <111> loops appearing as round-shaped loops. 

The boundary between half-cell compartments, commonly a salt bridge, is represented by a double vertical line ( ). Species in aqueous solution are placed on either side of the double vertical line. Different species within the same solution are separated from each other by a comma. Although lUPAC recommends the use of double dashed vertical lines to represent the salt bridge, the recommendation has not yet been universally adopted by chemists. In this text, we will continue to use the double vertical line (II) for a salt bridge. 

In a double covalent bond, two pairs of electrons are shared between bonded atoms. The bond is represented by a double-dash sign (=). 

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