Synthesis of a Novel Family of Polysilsesquioxanes Having Oligothiophenes with Well-Defined Structures

Our recent results on the synthesis and properties of a novel family of polysilsesquioxanes having oligothiophenes were reviewed. The polymers anchored on SiO2 or ITO substrates showed excellent mechanical hardness due to the formation of a three-dimensional siloxane network structure and chemical linkage between polymer and the surface of metal-oxide substrates. Optical, electrochemical, and electrical properties of polymers were also investigated

Effects of annealing of poly(3-hexylthiophene) film on the performance of double-layered EL devices of ITO/polymer/Alq3/Mg-Ag

Double layer devices with a structure of ITO/pHT/Alq3/Mg-Ag (ITO = indium tin oxide, pHT = regio-regular or random poly(3-hexylthiophene), Alq3 = tris(8-hydroxyquinoline)aluminium) were fabricated. The device with a random pHT film emitted a green-yellow light in all voltage region, while that having a regio-regular pHT film exhibited a color change from green to red by applying the bias voltage higher than 15 V. Annealing the pHT films prepared on ITO at 200 °C for 1 h in nitrogen, prior to vapor-deposition of the Alq3 layer, improved the device performance with lowering the onset bias voltage by 2-3 V. The EL colors and spectra were also affected by annealing. X-ray reflectivity measurements before and after annealing the pHT film on ITO indicated increased density of the pHT layer and structural changes in the pHT/ITO interface by annealing, which seems to be responsible for the improved EL device performanc

Synthesis, characterization, and photovoltaic applications of dithienogermole-dithienylbenzothiadiazole and -dithienylthiazolothiazole copolymers

New dithienogermole-based conjugated polymers were synthesized by the Stille coupling reactions of distannyldithienogermole and dibromoarene, and their photovoltaic properties were studied. These polymers possess low band gaps with broad absorptions covering the 400-800 nm range, and exhibit good film forming properties. Bulk hetero-junction solar cells prepared from blends of these polymers with PC(70)BM exhibit high power conversion efficiency up to 2.38%

Cricotracheostomy for patients with severe COVID-19: A case control study

BackgroundTracheostomy is an important procedure for the treatment of severe coronavirus disease-2019 (COVID-19). Older age and obesity have been reported to be associated with the risk of severe COVID-19 and prolonged intubation, and anticoagulants are often administered in patients with severe COVID-19; these factors are also related to a higher risk of tracheostomy. Cricotracheostomy, a modified procedure for opening the airway through intentional partial cricoid cartilage resection, was recently reported to be useful in cases with low-lying larynx, obesity, stiff neck, and bleeding tendency. Here, we investigated the usefulness and safety of cricotracheostomy for severe COVID-19 patients.Materials and methodsFifteen patients with severe COVID-19 who underwent cricotracheostomy between January 2021 and April 2022 with a follow-up period of ≥ 14 days were included in this study. Forty patients with respiratory failure not related to COVID-19 who underwent traditional tracheostomy between January 2015 and April 2022 comprised the control group. Data were collected from medical records and comprised age, sex, body mass index, interval from intubation to tracheostomy, use of anticoagulants, complications of tracheostomy, and decannulation.ResultsAge, sex, and days from intubation to tracheostomy were not significantly different between the COVID-19/cricotracheostomy and control/traditional tracheostomy groups. Body mass index was significantly higher in the COVID-19 group than that in the control group (P = 0.02). The rate of use of anticoagulants was significantly higher in the COVID-19 group compared with the control group (P < 0.01). Peri-operative bleeding, subcutaneous emphysema, and stomal infection rates were not different between the groups, while stomal granulation was significantly less in the COVID-19 group (P = 0.04).ConclusionsThese results suggest that cricotracheostomy is a safe procedure in patients with severe COVID-19

Electrical conduction mechanism in conjugated polymers studied using Flicker noise spectroscopy

We have performed detailed analysis of the fluctuations of the electrical current in electrochemically deposited conductive polymers (CP) using as example polyaniline and poly(3- methylthiophene). These heterogeneous and disordered materials cannot be analyzed in terms of classical conduction mechanisms (like Schottky or Poole-Frenkel emission). Instead, the electrical transport in CPs is to be considered as a stochastic process with large component of noise. We have been able to distinguish several modes of the conduction process in CPs by applying Flicker Noise Spectroscopy. Thus, we have established that the transport of charge carriers in highly doped CPs is much less correlated than in non-doped ones at the same electric field strength. While applied electric field increases, correlations become lower in a sequence of elementary events contributing to the conductivity of CP. Apparently, the change in the correlation length corresponds to changing mechanism of the electrical conduction. The lower correlation in highly doped sample can be attributed to various factors including change in CP conformation, enhancement in interchain charge transfer and generation of polaron lattice

Light reflection at polyaniline films and its application to a kinetic study of polymer chain conformation

Light reflection at polymer-coated electrodes is studied for polyaniline, poly(o-methylaniline), and poly(o-methoxyaniline). Reflected light intensity is found to be affected greatly by the applied potential for the two reasons: one is absorption of light due to coloring of the oxidized polymer film and the other is light scattering which is concerned with a polymer chain conformation upon oxidation. A new method based on the potential dependence of light reflection is proposed for studying kinetics of conformational changes of polymer chains. The rate constants evaluated are in the range of 0.05-8 s-1 at room temperature, depending on the sort of polymers, the film thickness, and pH of the solution. Irrespective of the sort of polymers, the increase in film thickness or solution pH leads to the decrease of the rate constant. It is found that a film morphology has a significant effect on the rate constant, as confirmed by a comparison of rate constants observed with polyaniline films grown at different rates

Bilayer polymer coating containing a polyaniline for corrosion protection of iron

A poly(2-N-phenylamino-4,6-dimercapto-S-triazine) (PPDT) layer was first prepared electrochemically on an iron surface. The PPDT layer strongly adsorbed on the surface because of the polar triazine rings of the PPDT molecules. No electrochemical response of the PPDT layer covered electrode to dissolved Fe(CN)6 3- was observed. This fact indicated that the PPDT layer is an insulating layer with low permeability to dissolved species, and thus acting as a diffusion barrier against agents causing corrosion such as H2O and O2. A polymer polyaniline (PANI) layer was electrodeposited on the PPDT layer. This system was conductive because electron transfer through the PPDT layer occurred by electrons hopping utilizing the localized electron density of the triazine ring. The obtained PANI/PPDT bilayer coating greatly lowered the anodic current peak ascribed to the anodic dissolution of iron and the corrosion current. The high anti-corrosion ability was due to a hybrid effect of the PANI layer as an in-situ oxidant and the PPDT layer as a diffusion barrier