Highly Efficient Blue Fluorescent Organic Light-Emitting Devices Based on λ5-Phosphinine Derivatives.

Although λ5-phosphinine derivatives are known as a promising class of blue fluorescent emitters, those photoluminescent quantum yield (PLQY) values have been reached up to 92 %, however, only a few examples have been explored as an emitter for blue organic light-emitting device (OLED), and the external quantum efficiency (EQE) has been below 2.4 % so far. In this study, we newly developed two types of blue λ5-phosphinine derivatives namely CN-COCF3 and CO2Me-CHO, and investigated the photophysical properties in the solid states. The photophysical analyses in solid state films suggested that the strong electron-accepting nature of these λ5-phosphinine derivatives caused the inferior PLQY values, and the exciplex formation with the host and neighboring materials should be avoided to improve the device efficiency. By choosing suitable host and neighboring materials with deep ionization potentials, we successfully realized efficient blue fluorescent OLEDs with EQE of over 4 % and CIE (0.14, 0.18). This is among the best in λ5-phosphinine-based blue OLEDs so far.

[Relationship between cough peak flow and onset of pneumonia in residents of geriatric health services facilities].

AIM: Sputum expectoration is associated with cough strength, which can be evaluated by cough peak flow (CPF). Since sputum expectoration can be difficult for patients with reduced CPF, they are more likely to have risk factors for pneumonia. We conducted a study to clarify factors contributing to CPF in residents of geriatric health services facilities and to assess the relationship between CPF and the onset of pneumonia. METHODS: We included 41 male residents of geriatric health services facilities from September to the middle of October 2018. We recorded each subject's age, body mass index (BMI), Performance Status (PS), nursing care level, Functional Independence Measure (FIM), pulse rate, percutaneous arterial oxygen saturation (SpO2), hand grip strength, Charlson comorbidity index, underlying diseases and rales upon auscultation. We also used Pearson's correlation analysis to analyze the relationship between CPF and the above factors. Subjects were assigned to 2 groups according to median CPF to determine the between-group relationships of these factors. Finally, subjects were followed up for 6 to 11 months after CPF measurement to confirm whether or not they developed pneumonia. RESULTS: CPF was positively correlated with BMI (nutritional parameter), hand grip strength (index of systemic muscular strength), and SpO2 The median CPF was 240 L/minute, and subjects were divided into 2 groups based on this valus: CPF ≤240 L/minute group (n=21) and CPF >240 L/minute group (n=20). Subjects in the CPF ≤240 L/minute group demonstrated lower BMI and hand grip strength but more pronounced rales upon auscultation. No statistically significant difference was observed between the 2 groups during the 6-month folloe-up. However, the 11-month follow-up demonstrated a higher incidence of pneumonia in the CPF ≤240 L/minute group. CONCLUSION: The above findings suggest that subjects with reduced CPF are more likely to develop pneumonia. To increase CPF, muscle rehabilitation therapy and nutrition management should be provided to residents of geriatric health services facilities to prevent pneumonia.

Chiral gas chromatography of 2,5-diketopiperazines following a ring-opening derivatization method for complete isomeric separation.

2,5-Diketopiperazines (DKPs) are widely recognized as chiral molecules with great potential in medicinal chemistry. Complete separation of DKP stereoisomers is very important for efficiently investigating the chemical characteristics of DKPs. The combination of esterification and acylation caused the enantiomers of cyclo(d-Ala-d-Ala) and cyclo(l-Ala-l-Ala) to ring-open and generate their dipeptide derivatives. These derivatives were completely separated by chiral gas chromatography (GC), and the determined isomer ratios were the same as the original isomer ratios. The derivatization also caused the ring-opening of cyclo(l-Asp-l-Phe) and cyclo(l-Met-l-Pro), and their derivatives were determined by the chiral GC method. The present study is the first report of the complete separation of cis-DKPs using chiral GC. This separation procedure can substantially contribute to the development of the chemistry of chiral DKPs.