ABSTRACT
A series of linear carboxylic acids containing diacetylenic units at different positions along the chain (C12 H25 (C≡C)2 (CH2 )n COOH, n=7-11) were vacuum-deposited on clean silica substrates. The morphologies of the initial films after UV irradiation were studied. A clear odd-even effect on the morphology of the initial film was observed in that, depending on the spacer length between the diacetylenic unit and carboxyl head group, rings or dendrites of acid dimer layers were obtained. A molecular dynamic simulation of the aggregation process suggests that two competing intermolecular interactions and thus aggregation directions are involved and modulated by the odd or even carbon chain length. Further modulation of the interaction by substitution of a phenyl group at the terminus of the chain or by changing the carboxyl head group to an amidobenzoic acid head group led to a similar odd-even effect but with different dimensions or trends, which can be rationalized similarly. These results give the opportunity to create aligned conjugated polymer chains of different dimensions through self-assembly for applications in molecular/organic electronics.
ABSTRACT
<p><b>OBJECTIVE</b>To distinguish female and male plants of Gynostemma pentaphyllum quickly and accurately in the stage of seedling and to understand the relation between sex differentiation and endogenous plant hormone.</p><p><b>METHOD</b>Stained methods of BTB and enzyme linked immuno-sorbent Assay were used.</p><p><b>RESULT</b>10 Hours after being dyed, the liquid extract of female plants turned into yellow, while extract of male ones turned green. There were obvious differences on iPAs and GA(1 + 3) contents but no differences on IAA and ABA contents between male and female plants during the stages of seedling and vegetative growth.</p><p><b>CONCLUSION</b>BTB can be used for distinguishing female and male plants and there were a certain relation between sex and endogenous plant hormones.</p>
