Line structures

AEBIL A New Acoustic Emission System for On-line Structural Integrety Monitoring of Critical Plant Components. 

A new acoustic emission system (AEBIL Acoustic Emission Binary Localizer) meeting the requirements for continuous on-line structural surveillance of critical conponents of operating plants Is described in the paper. The system is specifically designed to identify and locate structurally significant, spatially concentrated, AE sources in the presence of a high rate of spatially diffuse AE events. The system performance and reliability has been extensively demonstrated in In-plant applications. 

Results of Long-term On-line Structural Integrity Surveillance of H.T./H.P. Steam Headers by an Innovative Acoustic Emission Approach. 

F. Cattaneo, C. De Michelis, S. Ghia, G.M.Piana "AEBIL a new acoustic emission system for on-line structural integrity monitoring of critical power plant components" to be presented at the 7th European Conference on Non-Destructive Testing, Copenhagen, 26-29 May 1998. 

ChemSketch has some special-purpose building functions. The peptide builder creates a line structure from the protein sequence defined with the typical three-letter abbreviations. The carbohydrate builder creates a structure from a text string description of the molecule. The nucleic acid builder creates a structure from the typical one-letter abbreviations. There is a function to clean up the shape of the structure (i.e., make bond lengths equivalent). There is also a three-dimensional optimization routine, which uses a proprietary modification of the CHARMM force field. It is possible to set the molecule line drawing mode to obey the conventions of several different publishers. 

Figure 2 Calculated Hg L3-edge specu a (a) at 1.5 GPa with hypothetical zincblende (full line) and cinnabar (dashed line) structures (b) at 8GPa with hypothetical cinnabar (dashed line) and rocksalt (full line) structures.

Organic chemists have found a way to draw complex molecular structures in a very simple way, by not showing the C and H atoms explicitly. A line structure represents a chain of carbon atoms by a zigzag line, where each short line indicates a bond and the end of each line represents a carbon atom. Atoms other than C and H are shown by their symbols. Double bonds are represented by a double line and triple bonds by a triple line. Because carbon almost always forms four bonds in organic compounds, there is no need to show the C—FI bonds explicitly. We just fill in the correct number of hydrogen atoms mentally compare the line structure of 2-chlorobutane, QT3C1TC1CF12C]T3 (3a), with its structural form (3b). Line... 

Benzene, C6H(l, is another molecule best described as a resonance hybrid. It consists of a planar hexagonal ring of six carbon atoms, each one having a hydrogen atom attached to it. One Lewis structure that contributes to the resonance hybrid is shown in (11) it is called a Kekulc structure. The structure is normally written as a line structure (see Section C), a simple hexagon with alternating single and double lines (12). 

A line structure (introduced in Section C) represents a chain of carbon atoms as a zigzag line. The end of each short line in the zigzag represents a carbon atom. Because carbon nearly always has a valence of 4 in organic compounds, we do not need to show the C—H bonds. We just fill in the correct number of hydrogen atoms mentally, as we see for methylbutane (6), isoprene (7), and propyne (8). As explained in Section 2.7, a benzene ring is represented by a circle inside a hexagon, and we need to remember that one hydrogen atom is attached to each carbon atom. 

The following names of organic molecules are incorrect. Draw line structures and determine the correct systematic name for (a) 4-methyl-3-propvlheptane (b) 4,6-dimethyloctane ... 

Write the chemical formula ol the compound represented by each of the following line structures ... 

The structures of the following molecules can be 5 found on the Web site for this text. Draw the line structure of each and identify its chiral carbon atoms ... 

Stem-Gerlach experiment The demonstration of the quantization of electron spin by passing a beam of atoms through a magnetic field, stick structure See line structure. stock solution A solution stored in concentrated form, stoichiometric coefficients The numbers multiplying chemical formulas in a chemical equation. 

In Chapter 1, we introduced one of the best ways of drawing molecules, bond-line structures. They are fast to draw and easy to read, but they have one major deficiency they do not describe molecules perfectly. In fact, no drawing method can completely describe a molecule using only a single drawing. Here is the problem. 

Chemists use both chemical names and molecular pictures to describe molecules. Molecular pictures take several forms, including structural formulas, ball-and-stick models, space-filling models, and line structures. These molecular representations can help you improve your ability to think molecules. ... 

The chemistry of living processes is complex, and many carbon-based molecules found in living organisms have extremely complicated stmctures. Because of this complexity, chemists have developed line structures, which are compact representations of the stmctural formulas of carbon compounds. Line structures are constructed according... 

Construct line structures for the compounds with the following structural formulas ... 

A line structure is built by using information about how atoms are connected in the molecule. The stmctural formula is the basis for the line stmeture. Apply the guidelines to convert the structural formula representation into a line-structure representation. 

According to the fourth guideline, carbon atoms are not labeled, so we remove the C s These are the line structures for the three molecules ... 

To check that the line structures represent the correct substances, count the number of intersections and line ends, which should equal the number of C atoms in the compound. The first line structure has five, the second has three, and the third has five, matching the chemical formulas. 

C03-0002. Draw the line structures for the compounds that appear in Figures 322 and 3-3. 

Keep in mind that carbon atoms are not shown in a line structure, so the first step in constructing a structural formula from a line structure is to place a C at every line intersection and at the end of eveiy line. Then add singly bonded hydrogen atoms (—H) until every carbon atom has four bonds. Example 3-3 illustrates this procedure. 

The line structure demonstrates how the atoms are connected in the molecule, but we do not need this information because the chemical formula is provided. We use the chemical formula to calculate the... 

C03-0019. Determine the molar mass of malathion, an insecticide whose line structure and chemical formula appear in the margin. 

C03-0049. Write structural formulas for the molecules in Problem 3.1. C03-0050. Write structural formulas for the molecules in Problem 3.2. C03-0051. Convert the following structural formulas into line structures ... 

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