Surface Defect Formation and Passivation in Formamidinium Lead Triiodide (FAPbI3) Perovskite Solar Cell Absorbers.

Formamidinium lead iodide based hybrid perovskite materials with improved efficiency and stability still lack well-understood surface defect formation mechanisms. Controlling the surface termination and defects has the potential to improve the performance of both conventional 3D and latterly reduced-dimensional perovskites photovoltaics. Here, we characterized the termination and all possible defect formations in FAPbI3 surface by the first-principles calculations. We found that, among the surfaces we considered, FAI-termination exhibits the most stable surface with a high defect tolerance. The PbI2-terminated surface is also found to be relatively stable; however, certain defects, such as electron-donating FA-interstitial and Pb-interstitial defects, can create deep-level stable charge-traps, potentially limiting the optoelectronic performance. We further investigate the surface treatment on these deep defects by model small molecule additives. We found that benzene additive with delocalized electron distribution can effectively passivate the deep FA-interstitial and Pb-interstitial defects by electron donating to the surface defect through charge-transfer.

Para-spinal abscess following gallstones spillage during laparoscopic cholecystectomy: an unusual presentation.

Gallbladder perforation with subsequent gallstone spillage can occur with higher frequency in laparoscopic cholecystectomy than in traditional open approach. Gallstone abscess formation from stone spillage post-cholecystectomy is extremely rare. We present a case of para-spinal abscess formation 5 years after spilled gallstones following laparoscopic cholecystectomy.

Randomized clinical trial of a simple pulmonary recruitment manoeuvre to reduce pain after laparoscopy.

BACKGROUND: Shoulder tip and abdominal pain following laparoscopic procedures are well recognized causes of postoperative morbidity. In this double-blind randomized clinical trial attempts were made to reduce postoperative pain in patients undergoing laparoscopic surgery by implementing a simple intraoperative technique. METHODS: Patients undergoing elective laparoscopic cholecystectomy or laparoscopic transabdominal preperitoneal inguinal hernia repair were randomized to receive either the current standard treatment (control group) or an intervention to remove residual carbon dioxide. In the intervention group, the pneumoperitoneum was removed at the end of the operation by placing the patient in the Trendelenburg position and utilizing a pulmonary recruitment manoeuvre consisting of two manual inflations to a maximum pressure of 60 cmH2 O. In the control group, residual pneumoperitoneum was evacuated at the end of the procedure by passive decompression via the open operative ports. RESULTS: Seventy-six randomly assigned patients, 37 in the intervention group and 39 in the control group, were recruited. Overall postoperative pain scores were significantly lower in the intervention group (P = 0·001). Median (interquartile range) pain scores were significantly lower in the intervention group compared with the control group at both 12 h (3·5 versus 5; P < 0·010) and 24 h (3 versus 4·5; P < 0·010). CONCLUSION: Active evacuation of residual pneumoperitoneum following laparoscopic procedures, by means of two pulmonary recruitment manoeuvres in the Trendelenburg position, reduces postoperative pain significantly. This simple and safe technique can be implemented routinely after abdominal laparoscopy. REGISTRATION NUMBER: NCT01720433 (http://www.clinical trials.gov).