Revision balloon kyphoplasty and vertebra-pediculoplasty using cannulated screws for osteoporotic vertebral fractures with cement dislodgement following conventional balloon kyphoplasty.

We report the usefulness of revision balloon kyphoplasty (re-BKP) and vertebra-pediculoplasty using cannulated screws (VPCS) for osteoporotic vertebral fractures (OVF) following cement dislodgement of conventional BKP. Between 2015 and 2020, three patients with OVF developed symptomatic cement dislodgement following BKP and underwent re-BKP. All three patients showed a loose cemented mass and spinal instability. Balloon inflation was performed in the gap between the loosened cemented mass and the remaining cortical bone rim, and this extended gap was filled with cement. To prevent re-dislodgement of the cement mass, a cannulated screw was inserted into the cemented mass through the pedicle. All patients achieved early pain relief, and improved vertebral stability of the fractured vertebra and all related symptoms, with no perioperative complications. Re-BKP and VPCS are innovative concepts and could be an effective minimally invasive treatment for OVF following cement dislodgement of conventional BKP treatment.

Carrier density effect on recombination in PTB7-based solar cell.

Organic solar cells (OSCs) are promising alternatives to the conventional inorganic solar cells due to their low-cost processing and compatibility with flexible substrates. The development of low band-gap polymer, e.g., poly-[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3]thiophenediyl]] (PTB7), increases the power conversion efficiency (PCE) in the last decade. Here, we investigated the interrelation between the instantaneous carrier density (n) per donor (D)/acceptor (A) interface area and the carrier density (ncollected) collected as photocurrent in PTB7/C70 heterojunction (HJ) device. By means of the time-resolved spectroscopy, we confirmed that the exciton-to-carrier conversion process takes place within ~1 ps at the D/A interface of the PTB7/C70 HJ device. We further determined the absolute magnitude of n by combination of the time-resolved and electrochemical spectroscopies. We found that the carrier recombination becomes dominant if n exceeds a critical concentration (nc = 0.003 carriers/nm(-2)). We confirmed that a similar behaviors is observed in the PTB7/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) bulk heterojunction (BHJ) device. Our quantitative investigation based on the HJ device demonstrates that the fast carrier escape from the D/A interface region is indispensable for high PCE, because the carrier accumulation nonlinearly accelerates the carrier recombination process.

Fullerene mixing effect on carrier formation in bulk-hetero organic solar cell.

Organic solar cells (OSCs) with a bulk-heterojunction (BHJ) are promising energy conversion devices, because they are flexible and environmental-friendly, and can be fabricated by low-cost roll-to-roll process. Here, we systematically investigated the interrelations between photovoltaic properties and the domain morphology of the active layer in OSCs based on films of poly-(9,9-dioctylfluorene-co-bithiophene) (F8T2)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) blend annealed at various temperatures (Tan). The scanning transmission X-ray microscopy (STXM) revealed that fullerene mixing (ΦFullerene) in the polymer matrix decreases with increase in Tan while the domain size (L) is nearly independent of Tan. The TEM-S mapping image suggests that the polymer matrix consist of polymer clusters of several nm and fullerene. We found that the charge formation efficiency (ΦCF), internal quantum efficiency (ΦIQ), and power conversion efficiency (PCE) are dominantly determined by ΦFullerene. We interpreted these observations in terms of the polymer clusters within the polymer matrix.