Novel Carbazole-Based Hole-Transporting Materials with Star-Shaped Chemical Structures for Perovskite-Sensitized Solar Cells.

Novel carbazole-based hole-transporting materials (HTMs), including extended π-conjugated central core units such as 1,4-phenyl, 4,4'-biphenyl, or 1,3,5-trisphenylbenzene for promoting effective π-π stacking as well as the hexyloxy flexible group for enhancing solubility in organic solvent, have been synthesized as HTM of perovskite-sensitized solar cells. A HTM with 1,3,5-trisphenylbenzene core, coded as SGT-411, exhibited the highest charge conductivity caused by its intrinsic property to form crystallized structure. The perovskite-sensitized solar cells with SGT-411 exhibited the highest PCE of 13.00%, which is 94% of that of the device derived from spiro-OMeTAD (13.76%). Time-resolved photoluminescence spectra indicate that SGT-411 shows the shortest decay time constant, which is in agreement with the trends of conductivity data, indicating it having fastest charge regeneration. In this regard, a carbazole-based HTM with star-shaped chemical structure is considered to be a promising candidate HTM.

Effect of H2O2 bleaching with ultrasonication on the properties of thermomechanical pulp and unbleached kraft pulp.

H2O2 was used in the final stage of a multistage bleaching process to increase ISO brightness by 2-3%, because of the poor selectivity and bleachability. However, concerns about the environmental load of the bleaching process have led to the efficient use of oxygen-derived compounds, with a concomitant decrease in the quantity of chlorine-derived compounds consumed. In this study, thermomechanical pulp (TMP) and unbleached kraft pulp (UKP) were bleached with H2O2 and ultrasonicated in order to increase the bleaching efficiency, and the effects of some bleaching conditions such as treatment time, treatment concentration, and temperature were determined. The best bleaching efficiency of pulp was obtained using H2O2 with ultrasonication (at 20 kHz) of the pulp mixture at 45 °C for 30 min. The ISO brightness of the bleached pulp increased up to 1.9%, although the bleached pulp yield was slightly reduced to 1.5%. Magnesium sulfate was used as a bleaching stabilizer to increase the bleached pulp yield and viscosity. As a result, the bleached pulp yield and viscosity increased by 2.1% and 10%, compared with fully bleached pulp at the end of the process, respectively, despite a decrease in ISO brightness.

14.8% perovskite solar cells employing carbazole derivatives as hole transporting materials.

Three novel carbazole-based molecules have been synthesized and successfully applied as hole-transporting materials (HTMs) of CH3NH3PbI3-based perovskite solar cells. In particular, the perovskite cell with SGT-405, having a three-arm-type structure, exhibited a remarkable photovoltaic conversion efficiency (PCE) of 14.79%.

Long-term comparison of fixed-bearing and mobile-bearing total knee replacements in patients younger than fifty-one years of age with osteoarthritis.

BACKGROUND: There is limited information comparing the results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in patients with osteoarthritis who are younger than fifty-one years and who have a fixed-bearing implant in one knee and a mobile-bearing implant in the other. The purpose of this study was to compare our long-term clinical and radiographic results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in a group of patients from this population. METHODS: We prospectively compared the results of 108 patients with osteoarthritis who were younger than fifty-one years (mean age, forty-five years) who had received a fixed-bearing prosthesis in one knee and a rotating platform mobile-bearing prosthesis in the other. The mean follow-up was 16.8 years (range, fifteen to eighteen years). The patients were assessed clinically and radiographically. Knee motion and function were assessed as a primary outcome. Patients were assessed with questionnaires, and each knee was assessed separately. RESULTS: Although there was significant improvement in both groups of knees, there was no significant difference between the groups (i.e., fixed-bearing and mobile-bearing knees) with regard to the mean postoperative knee motion (126° and 128°, respectively; p = 0.79), the mean Knee Society knee clinical score (95 and 94 points, respectively; p = 0.79), or the Knee Society knee functional score (84 and 85 points, respectively; p = 0.19) at the latest follow-up. In the fixed-bearing group, one knee was revised because of infection, two for aseptic loosening of the tibial component, and two because of wear of the tibial polyethylene insert. In the rotating platform mobile-bearing group, two knees were revised because of instability and one because of infection. The Kaplan-Meier survivorship for revision at 16.8 years of follow-up was 95% (95% confidence interval, 91 to 100) for the fixed-bearing prosthesis and 97% (95% confidence interval, 93 to 100) for the rotating platform mobile-bearing prosthesis. CONCLUSIONS: Long-term results of both fixed and mobile-bearing total knee arthroplasties were encouraging in patients who were younger than fifty-one years of age with osteoarthritis. However, we found no superiority of the mobile-bearing total knee prosthesis over the fixed-bearing total knee prosthesis.

Role of p16 in the pathogenesis of Langerhans cell histiocytosis.

BACKGROUND: It has been hypothesized that genetic alteration at the cellular level may have a significant effect on cellular mechanisms controlling the proliferation and apoptosis of Langerhans cells (LCs). METHODS: We examined whether p16 protein expression can be used to predict the outcome of Langerhans cell histiocytosis (LCH). Archival paraffin blocks from children diagnosed with LCH and followed at the Asan Medical Center and Chungnam National University Hospital between March 1998 and February 2008 were studied. RESULTS: Slides were stained with p16 antibody and evaluated semi-quantitatively using the following scale: negative, no staining; ±, weakly positive; 1+, staining similar to lymphocytes surrounding the LCs; 2+, stronger staining than lymphocytes; 3+, much stronger staining than lymphocytes. Negative and ± groups were assigned to a lower expression group (LEG) and the 1+, 2+, and 3+ groups were assigned to a higher expression group (HEG). The median age of the 51 patients (24 girls, 27 boys) was 49 (range, 0.6-178) months, and LCH was diagnosed based on CD1a positivity. p16 protein was expressed to varying degrees in all but one specimen. There was a greater tendency toward multisystem disease, risk organ involvement, and relapse in the HEG than in the LEG. CONCLUSION: The p16 protein may have a significant effect on cellular mechanisms controlling the proliferation and apoptosis of LCs, and thus may influence the clinical outcome and prognosis of LCH.

Surgical correction of fixed kyphosis.

STUDY DESIGN: A retrospective review was carried out on 23 patients with rigid fixed kyphosis who underwent surgical correction for their deformity. PURPOSE: To report the results of surgical correction of fixed kyphosis according to the surgical approaches or methods. OVERVIEW OF LITERATURE: Surgical correction of fixed kyphosis is more dangerous than the correction of any other spinal deformity because of the high incidence of paraplegia. METHODS: There were 12 cases of acute angular kyphosis (6 congenital, 6 healed tuberculosis) and 11 cases of round kyphosis (10 ankylosing spondylitis, 1 Scheuermann's kyphosis). Patients were excluded if their kyphosis was due to active tuberculosis, fractures, or degenerative lumbar changes. Operative procedures consisted of anterior, posterior and combined approaches with or without total vertebrectomy. Anterior procedure only was performed in 2 cases, while posterior procedure only was performed in 8 cases. Combined procedures were used in 13 cases, including 4 total vertebrectomies. RESULTS: The average kyphotic angle was 71.8 degrees preoperatively, 31.0 degrees postoperatively, and the average final angle was 39.2 degrees . Thus, the correction rate was 57% and the correction loss rate was 12%. In acute angular kyphosis, correction rate of an anterior procedure only was 71%, correction rate of the combined procedures without total vertebrectomy was 49% and correction rate of the combined procedures with total vertebrectomy was 60%. In round kyphosis, correction rate of posterior procedure only was 65% and correction rate of combined procedures was 59%. The clinical results according to the Kirkaldy-Willis scale demonstrated 17 excellent outcomes, 5 good outcomes and one poor outcome. CONCLUSIONS: Our data indicates that the combined approach and especially the total vertebrectomy showed the safety and the greatest correction rate if acute angular kyphosis was greater than 60 degrees.