Use of side-chain for rational design of n-type diketopyrrolopyrrole-based conjugated polymers: what did we fing out?

Cataloged from PDF version of article.The primary role of substituted side chains in organic semiconductors is to increase their solubility in common organic solvents. In the recent past, many literature reports have suggested that the side chains play a critical role in molecular packing and strongly impact the charge transport properties of conjugated polymers. In this work, we have investigated the influence of side-chains on the charge transport behavior of a novel class of diketopyrrolopyrrole (DPP) based alternating copolymers. To investigate the role of side-chains, we prepared four diketopyrrolopyrrole-diketopyrrolopyrrole (DPP-DPP) conjugated polymers with varied side-chains and carried out a systematic study of thin film microstructure and charge transport properties in polymer thin-film transistors (PTFTs). Combining results obtained from grazing incidence X-ray diffraction (GIXD) and charge transport properties in PTFTs, we conclude side-chains have a strong influence on molecular packing, thin film microstructure, and the charge carrier mobility of DPP-DPP copolymers. However, the influence of side-chains on optical properties was moderate. The preferential "edge-on" packing and dominant n-channel behavior with exceptionally high field-effect electron mobility values of >1 cm(2) V-1 s(-1) were observed by incorporating hydrophilic (triethylene glycol) and hydrophobic side-chains of alternate DPP units. In contrast moderate electron and hole mobilities were observed by incorporation of branched hydrophobic side-chains. This work clearly demonstrates that the subtle balance between hydrophobicity and hydrophilicity induced by side-chains is a powerful strategy to alter the molecular packing and improve the ambipolar charge transport properties in DPP-DPP based conjugated polymers. Theoretical analysis supports the conclusion that the side-chains influence polymer properties through morphology changes, as there is no effect on the electronic properties in the gas phase. The exceptional electron mobility is at least partially a result of the strong intramolecular conjugation of the donor and acceptor as evidenced by the unusually wide conduction band of the polymer

The rate of the founder Jewish mutations in BRCA1 and BRCA2 in prostate cancer patients in Israel

Inherited predisposition occurs in 5–10% of all prostate cancer (CaP) patients, but the genes involved in conferring genetic susceptibility remain largely unknown. Several lines of evidence indicate that germline mutations in BRCA1 and BRCA2 might be associated with an increased risk for CaP. Three mutations in these two genes (185delAG and 5382InsC (BRCA1) and 6174delT (BRCA2) occur in about 2.5% of the general Ashkenazi population, and the 185delAG BRCA1 mutation, in up to 1% of non-Ashkenazi Jews. In order to assess the contribution of these germline mutations to prostate cancer in Jewish Israeli patients, we tested 174 unselected prostate cancer patients (95 of Ashkenazi origin) for these mutations by PCR amplification and modified restriction enzyme digests. Patient’s age range was 45–81 years (median 66), and in 24 (14.4%) the disease was diagnosed prior to 55 years of age. Nineteen (11%) and 12 (6.9%) patients had a first or second degree relative with CaP or breast cancer, respectively. Overall, five mutation carriers were detected: 2/152 (1.3%) 185delAG, 2/104 (2%) 5382InsC, and 1/158 (0.6%) 6174delT. In all carriers, the disease was diagnosed after the age of 55, and only one of them had a family history of breast and CaP. In addition, no allelic losses at the BRCA1 locus were demonstrated in 17 patients with a family history of CaP, using seven microsatellite markers. We conclude that the rate of the predominant Jewish BRCA1 and BRCA2 mutations in CaP patients does not significantly differ from that of the general population, and that mutational inactivation of the BRCA1 is rare in familial CaP. Thus, germline BRCA1 and BRCA2 mutations probably contribute little to CaP occurrence, to inherited predisposition, and to early onset disease in Jewish individuals. © 2000 Cancer Research Campaig

New Fused Bis-Thienobenzothienothiophene Copolymers and Their Use in Organic Solar Cells and Transistors

A new tetradodecyl-substituted DTBTBT donor unit is synthesized by a specific bis-annulation via Suzuki–Miyaura coupling and successfully incorporated into light absorbing electron donor copolymers for OPV and hole and electron transport OFET polymer devices. All copolymers (DTBTBT-<i>co</i>-benzothiadiazole (Bz), DTBTBT-<i>co</i>-thiophene (T) and DTBTBT-<i>co</i>-thienothiophene (TT)) show fully coplanar backbones and strong intermolecular interactions. The DTBTBT-Bz copolymer led to a deep HOMO level (−5.2 eV) and thus a large <i>V</i>_oc value of 0.92 V with PC₇₁BM as electron acceptor and a PCE of 3.7% with a <i>J</i>_sc of 6.78 mA/cm² could be obtained. A hole mobility of 0.1 cm²/(V s) has been observed for the highly coplanar and more crystalline DTBTBT-T copolymer

Inibição da formação de abscesso abdominal em rato: mortalidade por sepse Inhibition of abdominal abscess formation in rat: Mortality by sepsis

RACIONAL: Atribui-se aos abscessos intra-abdominais e às aderências peritoniais a função de isolar os processos sépticos e proteger o organismo da bacteremia. Por outro lado, esses fenômenos também dificultam o afluxo de fatores imunitários e antibióticos para a região infectada. OBJETIVO: Avaliar o efeito da prevenção de abscessos na sobrevida após peritonite bacteriana. MÉTODOS: Foram estudados 30 ratos Wistar machos que receberam solução de fezes a 50% intra-abdominal e que foram distribuídos em três grupos (n = 10). Grupo 1: controle (solução de fezes); grupo 2: solução de fezes mais solução salina a 0,9%; grupo 3: solução de fezes mais carboximetilcelulose a 1%, para inibir a formação de aderências. Os três grupos foram divididos em dois subgrupos (n = 5): subgrupo A: nova laparotomia, após 4 dias, para inspeção da cavidade abdominal; e subgrupo B: acompanhamento durante 30 dias para avaliação da mortalidade e da causa de morte. A análise estatística utilizou o teste exato de Fisher. RESULTADOS: O acréscimo de solução salina a 0,9% não aumentou a mortalidade do grupo. Entretanto, no grupo em que se acrescentou a solução de carboximetilcelulose, houve menor formação de abscessos, que também foram mais tênues e a mortalidade aumentou em relação ao grupo controle. CONCLUSÃO: A inibição na formação de aderências peritoniais e de abscessos acompanha-se de maior mortalidade decorrente do processo séptico intra-abdominal generalizado