Branch lower

Another interesting effect seen in alkanes is that increased branching lowers an alkane s boiling point. Thus, pentane has no branches and boils at 36.1 3C, isopentane (2-methylbutane) has one branch and boils at 27.85 °C, and neopentane (2,2-dimethylpropane) has two branches and boils at 9.5 °C. Similarly, octane boils at 125.7 °C, whereas isooctane (2,2,4-trimethylpentane) boils at 99.3 °C. Branched-chain alkanes are lower-boiling because they are more nearly spherical than straight-chain alkanes, have smaller surface areas, and consequently have smaller dispersion forces. 

Valine (Val or V) ((5)-2-amino-3-methyl-butanoic acid) is a nonpolar, neutral, aliphatic amino acid with the formula HOOCCH(NH2)CH(CH3)2. Along with Leu and He, Val is a branched-chain amino acid and is found in high concentrations in the muscles. Val is needed for muscle metabolism and coordination, tissue repair, and for the maintenance of proper nitrogen balance in the body. ° The steric hindrance present in Val and He (caused by branching) lowers the rate of coupling reactions, resulting in an increase in side reactions. ... 

Symptoms Initially, bright orange pustules on leafstalks, branches, lower leaf surfaces, especially along veins, and on any hips from the previous year. During summer, yellow-orange pustules develop on lower leaf surfaces away from leaf veins. Later pustules become speckled with black spores that will overwinter. Rosa pimpinellifolia is particularly susceptible. 

FIGURE 12-IS Annual growth of the terminal shoot (upper) and first-order branches (lower) in upper half of ponderosa pine saplings maintained in filtered or unfiltered (ambient) air greenhouses, and an outside ambient-air treatment from 1%8 through 1973. Reprinted with permission from Kickert et al. 

Figure 3 The upper part of the HR diagram with evolutionary tracks calculated by Maeder and Meynet (1987). The branch of dots in the red part is the proposed Red Supergiant Branch. Lower to the right (at log Teff 3.4) is the uppermost part of the Asymptotic Giant Branch. The hatched area near log Teff = 3.75 is the upper part of the Cepheid branch. 

Increased branching lowers an alkane s boiling point. 

As a result, the Se content in leaves of Biluochun was elevated by approximately 50%. The highest tea Se concentration reached 291 J,g kg. Se contents in the tea tree tissues were as follows leaf > bud > lateral branch > upper branch > lower branch. 

Other points could be found in a similar manner. For example, if the same series of alloys were equilibrated at temperature T2, a parameter curve similar to Fig. 12-8(b) would be obtained, but its inclined branch would be shorter and its horizontal branch lower. But heat treatments and parameter measurements on all these alloys are unnecessary, once the parameter-composition curve of the solid solution has been established. Only one two-phase alloy is needed to determine the rest of the solvus. Thus, if alloy 6 is equilibrated at Tj and then quenched, it will contain a saturated at that temperature. Suppose the measured parameter of a in this alloy is a,. Then, from the parameter-composition curve, we find that a of parameter contains y percent B. This fixes a point on the solvus at temperature T2. Points on the solvus at other temperatures may be found by equilibrating the same alloy, alloy 6, at various temperatures, quenching, and measuring the lattice parameter of the contained a. 

Like other organic compounds, branching lowers the boiling points of ethers. 

Fig. 3.1. Antenna of the male satumiid moth Antheraea polyphemus. Upper panel Schematic view of the antenna. Each antennal stem segment has four side branches. Lower panel Two antennal segments enlarged with different types of sensilla. The numerous, long olfactory hairs contain two or three receptor neurons responding to two or three components of the female pheromone.

If the chain is substantially branched, the packing efficiency detmorates and the crystalline content is lowered. Polyethylene provides a good example (Figure 11.2), where extensive branching lowers the density and of the polymer. 

Description Herbaceous annual or biennial, 30-90 cm tall, covered with long, white, raised hairs. Stems single or multiple, erect, branched. Lower stem leaves petiolate, tripartite-pinnatisect, 3-7 cm long cauUne leaves sessile, tripartite. Inflorescences 3-5-flowered capitula in panicles. Disk flowers yellow, punctate glandular ray flowers absent. Fruits obo-vate achenes, 2-2.25 mm long, olive-colored. 

In a series of homologs, the boiling point increases with increasing molecular weight. Branching lowers the boiling point. 

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