ABSTRACT
Intermolecular orbital coupling is fundamentally important to organic semiconductor performance. Recently, we reported that 2,6':2',6â³-terazulene (TAz1) exhibited excellent performance as an n-type organic field-effect transistor (OFET) via molecular orbital distribution control. To validate and develop this concept, here we present three other terazulene regioisomers, which have three azulene molecules connected at the 2- or 6-position along the long axis of the azulene, thus constructing a linear expanded π-conjugation system: 2,2':6',2â³-terazulene (TAz2), 2,2':6',6â³-terazulene (TAz3), and 6,2':6',6â³-terazulene (TAz4). TAz2 and TAz3 exhibit ambipolar characteristics; TAz4 exhibits clear n-type transistor behavior as an OFET. The lowest unoccupied molecular orbitals (LUMOs) of all terazulenes are fully delocalized over the entire molecule. In contrast, the highest occupied molecular orbitals (HOMOs) of TAz2 and TAz3 are delocalized over the 2,2'-biazulene units; the HOMOs of TAz4 are localized at one end of the azulene unit. These findings confirm that terazulene isomers which are simple hydrocarbon compounds are versatile materials with a tunable-polarity FET characteristic that depends on the direction of the azulene unit and the related contrast of the molecular orbital distribution in the terazulene backbone.
ABSTRACT
BACKGROUND: Nontuberculous mycobacteria (NTM) are often detected in patients undergoing treatment for pulmonary tuberculosis. This clinical status is thought to represent NTM disease, contamination, or colonization, but discriminating between these three conditions is difficult. PURPOSE: We examined the clinical characteristics and pathogenicity of coexisting NTM among patients with pulmonary tuberculosis, as well as its impact on clinical practice. PATIENTS AND METHODS: The subjects comprised 59 patients with pulmonary tuberculosis treated at the National Hospital Organization Utsunomiya National Hospital between January and December 2013. Patients in whom NTM was detected in one or more cultures were defined as the NTM group (19 patients), and they were compared to the non-NTM group (40 patients). Antiglycopeptidolipid (anti-GPL) core antibody titers were investigated in 18 patients from the NTM group. RESULT: We observed no significant difference in patient characteristics (age, sex, complications, history of pulmonary tuberculosis, lung disease, chest imaging findings, degree of smear positivity on admission) between the two groups. Mean duration of hospitalization was markedly longer for the NTM group, excluding those with coexisting NTM after discharge (98.8 ± 7.9 days), than for the non-NTM group (58.3 ± 3.5 days; p < 0.001). No anti-GPL core antibodies were detected in any of the 18 patients from the NTM group, including 13 patients who fulfilled the ATS/IDSA criteria. CONCLUSION: Coexisting NTM observed during treatment for tuberculosis likely results from colonization or contamination and usually has low pathogenicity. However, this finding is related to prolonged hospitalization.
Subject(s)
Coinfection/microbiology , Mycobacterium Infections, Nontuberculous/microbiology , Nontuberculous Mycobacteria , Tuberculosis, Pulmonary/microbiology , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/therapeutic use , Coinfection/drug therapy , Female , Hospitalization , Humans , Male , Middle Aged , Mycobacterium Infections, Nontuberculous/drug therapy , Tuberculosis, Pulmonary/drug therapyABSTRACT
We present herein a linear expanded π-conjugation system comprising azulene units: 2,6':2',6â³-terazulene. This simple hydrocarbon exhibits excellent n-type transistor performance with an electron mobility of up to 0.29 cm(2) V(-1) s(-1). The lowest unoccupied molecular orbital (LUMO) is well distributed over the entire molecule, whereas the highest occupied molecular orbital (HOMO) is localized at one end. These findings indicate a disadvantage of hole carrier transport and an advantage of n-type-specific transport behavior. This system presents an unconventional concept: polarity control of OFET by molecular orbital distribution control.
