Highly Self-Healable Polymeric Coating Materials with Enhanced Mechanical Properties Based on the Charge Transfer Complex.

Polymeric coating materials (PCMs) are promising candidates for developing next-generation flexible displays. However, PCMs are frequently subjected to external stimuli, making them highly susceptible to repeated damage. Therefore, in this study, a highly self-healing PCM based on a charge transfer complex (CTC) was developed, and its thermal, self-healing, and mechanical properties were examined. The self-healing material demonstrated improved thermal stability, fast self-healing kinetics (1 min), and a high self-healing efficiency (98.1%) via CTC-induced multiple interactions between the polymeric chains. In addition, it eliminated the trade-off between the mechanical strength and self-healing capability that is experienced by typical self-healing materials. The developed PCM achieved excellent self-healing and superior bulk (in-plane) and surface (out-of-plane) mechanical strengths compared to those of conventional engineering plastics such as polyether ether ketone (PEEK), polysulfone (PSU), and polyethersulfone (PES). These remarkable properties are attributed to the unique intermolecular structure resulting from strong CTC interactions. A mechanism for the improved self-healing and mechanical properties was also proposed by comparing the CTC-based self-healing PCMs with a non-CTC-based PCM.

Over 500 Liver Transplants Including More Than 400 Living-Donor Liver Transplants in 2019 at Asan Medical Center.

BACKGROUND: More than 400 liver transplants were performed at Asan Medical Center (AMC) in 2011, and over 500 liver transplants including 420 living-donor liver transplants (LDLTs) were performed in 2019. Herein, we report the methodology of these procedures. METHODS: Since the first adult LDLTs at AMC using the left and right lobes were successfully performed, various innovative techniques and approaches have been developed: modified right lobe, dual graft, donor exchange for ABO incompatibility, expansion of indications and no-touch techniques for hepatocellular carcinoma, intraoperative cine-portogram and additional intervention for large collaterals, management of portal vein thrombosis (PVT) and stenosis, salvage LDLT after major hepatectomy, and timely LDLT for patients with acute-on-chronic liver failure. RESULTS: Four hundred twenty LDLTs in 403 adult and 17 pediatric patients and 85 deceased-donor liver transplants in 74 adult and 11 pediatric patients were performed. The number of deceased-donor liver transplants remained constant since 2011, but the number of LDLTs increased steadily. One hundred thirty patients (25.7%) required urgent liver transplantations and 24 patients with acute-on-chronic liver failure underwent LDLT. PVT including grade 1,2,3, and 4 was reported in 91 patients (18.0%), and Yerdel's grade 2, 3, and 4 PVT was reported in 47 patients (51.6%); all patients with PVT were successfully treated. Adult LDLTs for hepatocellular carcinoma and ABO incompatibility accounted for 52.6% and 24.3% of the cases, respectively. In-hospital mortality in 2019 was 2.97%. CONCLUSION: Continual efforts to overcome challenging problems in LDLT with various innovations and dedication of the team members during the perioperative period to improve patient outcomes were crucial in increasing the number of liver transplantations at Asan Medical Center.

A Heterocyclic Polyurethane with Enhanced Self-Healing Efficiency and Outstanding Recovery of Mechanical Properties.

A functional polyurethane based on the heterocyclic group was synthesized and its self-healing and mechanical properties were examined. To synthesize a heterocyclic polyurethane, a polyol and a heterocyclic compound with di-hydroxyl groups at both ends were blended and the blended solution was reacted with a crosslinker containing multiple isocyanate groups. The heterocyclic polyurethane demonstrates better self-healing efficiency than the conventional polyurethane with no heterocyclic groups. Furthermore, unlike the conventional self-healing materials, the heterocyclic polyurethane examined in this study shows an outstanding recovery of the mechanical properties after the self-healing process. These results are attributed to the unique supramolecular network resulting from the strong hydrogen bonding interaction between the urethane group and the heterocyclic group in the heterocyclic polyurethane matrix.

Low-Temperature Cross-Linkable Small Molecules for Fully Solution-Processed OLEDs.

Cross-linkable hole-transporting, host, and electron-transporting materials with a new cross-linking group, uracil, are designed and synthesized. These compounds exhibited good solubility in common organic solvents and excellent solvent resistance after cross-linking at a low temperature of 120 °C. The OLED was fabricated by all-solution processing using cross-linkable synthetic compounds, except for the electrodes. This device exhibited a current efficiency of 39.2 cd A-1 and a power efficiency of 15.3 lm W-1 .

Surgical treatment of mucin-producing cholangiocarcinoma arising from intraductal papillary neoplasm of the intrahepatic bile duct: a report of 2 cases.

Intraductal papillary neoplasms of the bile duct (IPNB) leads to malignant transformation and mucin production. Herein, we presented two cases of mucin-producing IPNB with obstructive jaundice who underwent resection of the intrahepatic lesions and bypass hepaticojejunostomy. The first case was a 69 year-old male patient with 5-year follow up for gallstone disease. Imaging studies showed mucin-secreting IPNB mainly in the hepatic segment III bile duct (B3) and multiple intrahepatic duct stones for which, segment III resection, intrahepatic stone removal, end-to-side choledochojejunostomy and B3 hepaticojejunostomy were conducted. The second case was a 74 year-old female patient with 11-year follow up for gallstone disease. Imaging studies showed mucin-producing IPNB with dilatation of the segment IV duct (B4) and mural nodules for which, segment IV resection, partial resection of the diaphragm and central hepaticojejunostomy were conducted. Both patients recovered uneventfully from surgery. These cases highlight that in patients with IPNB, abundant production of highly viscous mucin inducing obstructive jaundice may be associated with malignant transformation.

Conductivity Enhancement of PEDOT:PSS Films Through the Surface Treatment with Organic Solvent.

The improvement of conductivity is a key factor in application of conducting polymer to elec- tronic devices. The conductivity enhancement of PEDOT: PSS films were observed after dipping in polar organic solvents, including DMSO, ethylene glycol, glycerol and IPA. The conductivity of PEDOT: PSS films increased from 0.5 S/cm to over 800 S/cm, that is, by a factor of more than 1,600. The conductivity enhancement was dependent on the type of organic solvents and dipping time of PEDOT: PSS into solvent. The enhancement of conductivity may be caused by the phase separation between PEDOT chains and PSS counter anions.

Preoperative Left Portal Vein Embolization for Left Liver Resection in High-Risk Hepatobiliary Malignancy Patients.

BACKGROUND: Preoperative portal vein embolization (PVE) is performed for right liver (RL) and sometimes left liver (LL) resection to prevent postoperative surgical complications. METHODS: We retrospectively reviewed 10 patients who underwent preoperative left PVE before LL resection for hepatobiliary malignancies along with 3 propensity score-matched control groups (n = 40 each). RESULTS: Mean patient age was 68.6 ± 6.9 years. Diagnoses included intrahepatic cholangiocarcinoma (n = 4), perihilar cholangiocarcinoma (n = 3), neuroendocrine carcinoma (n = 1), recurrent cholangiocarcinoma (n = 1), and inflammatory liver mass (n = 1). The reason for left PVE was a large LL >40 % of the total liver volume (TLV) with a major comorbidity or age > 70 years with a poor overall condition. All patients underwent preplanned operations, including LL resection at 1-3 weeks post PVE. The LL volume proportion of the TLV was 44.9 ± 1.7 and 40.7 ± 2.3 % before and after PVE; thus, 1-2 weeks post PVE, the kinetic shrinkage rate of the LL was 9.4 ± 3.3 %, and the kinetic growth rate of the RL was 7.6 ± 2.7 %. The overall surgical complication rates were 40, 50, and 39.2 % in the left PVE, large LL control, and all three control groups, respectively (p ≥ 0.727). In contrast, the adjusted rates of major complications were 0 % in the left PVE group versus 36.8 % (p = 0.040), 25.6 % (p = 0.123), and 15.8 % (p = 0.295) in the large-, medium-, and small-sized LL control groups, respectively. CONCLUSIONS: Our experience indicates that left PVE is safe and induces atrophy of the LL effectively. We suggest that it can be a useful option to reduce the risk of postoperative complications in elderly high-risk patients.

Clinicopathological Features and Long-Term Outcomes of Intraductal Papillary Neoplasms of the Intrahepatic Bile Duct.

We intended to investigate the clinicopathological features of intrahepatic intraductal papillary neoplasms of the bile duct (IPNB), especially their malignant features and post-resection prognosis. Forty-three patients who met the definition of IPNB and who underwent liver resection between January 2002 and June 2015 were selected from our institutional database of liver resection cases. The mean age was 63.3 ± 6.9 years and 24 were male. Hepatolithiasis was present in addition in 10 of the patients. Left- and right-sided hepatectomies and concurrent bile duct resection (BDR) were performed in 28, 15, and 10 patients, respectively; R0 resection was performed in 37 patients. The mean tumor diameter was 4.1 ± 2.2 cm. Histological tumor grade was low in 4 cases, intermediate in 6, and malignant in 33. There was no cancer-related recurrence or death in the 10 patients with low-grade or intermediate lesions. In the 33 patients with malignant lesions, rates of tumor recurrence and overall survival were 12.5 and 96.2 % at 1 year, 36.4 and 91.3 % at 3 years, and 47.0 and 68.8 % at 5 years, respectively. Multivariate analysis showed that R1 resection was the only prognostic factor for tumor recurrence and patient survival. BDR was performed in only 2 of 6 patients undergoing R1 resection. Intrahepatic IPNB is a rare type of biliary neoplasm that encompasses a histological spectrum ranging from benign disease to invasive malignancy. Long-term survival was anticipated after curative resection. R1 resection reduced survival outcomes; therefore, we suggest that concurrent BDR should be performed if the resection margin of the bile duct is not reliably free of neoplastic involvement.

Preoperative Sequential Portal and Hepatic Vein Embolization in Patients with Hepatobiliary Malignancy.

BACKGROUND: Preoperative portal vein embolization (PVE) induces shrinkage of the embolized lobe and compensatory regeneration in the non-embolized lobe, but does not always induce sufficient regeneration of the future remnant liver (FRL). We previously developed preoperative sequential PVE-hepatic vein embolization (HVE), and here we present our experience of treating 42 patients with sequential PVE-HVE. METHODS: During 8-year study period, preoperative PVE-HVE was performed on 42 patients with hepatobiliary malignancies. RESULTS: Primary diseases were bile duct cancers [perihilar cholangiocarcinoma (n = 33) and diffuse bile duct cancer (n = 1)], hepatocellular carcinomas (n = 4), and intrahepatic tumors [intrahepatic cholangiocarcinoma (n = 3) and gallbladder cancer liver invasion (n = 1)]. These patients demonstrated insufficient FRL regeneration following PVE, thus HVE was performed to induce further regeneration. No PVE-HVE procedure-associated complications occurred. In the bile duct cancer group, FRL volume was 33.9 ± 2.2 % before PVE, 38.4 ± 1.5 % before HVE, 43.7 ± 2.1 % at surgery, and 73.6 ± 8.3 % at 2 weeks after right hepatectomy. The degree of FRL hypertrophy was 13.3 % after PVE, 28.9 % after PHV-HVE, and 117.1 % at 2 weeks after right hepatectomy. All patients except one recovered uneventfully after surgery, and the 3-year patient survival rate was 45.1 %. In the HCC group, transarterial chemoembolization was initially performed and FRL regeneration following PVE-HVE occurred very slowly. Active FRL regeneration occurred in the liver tumor group, but rapid tumor growth was observed in 1 of 4 patients. CONCLUSION: The sequential application of HVE following PVE safely and effectively induces further FRL regeneration in non-cirrhotic livers. Further validation using larger patient population and multicenter studies is needed to reliably widen the indications.

Photorealistic ray tracing to visualize automobile side mirror reflective scenes.

We describe an interactive visualization procedure for determining the optimal surface of a special automobile side mirror, thereby removing the blind spot, without the need for feedback from the error-prone manufacturing process. If the horizontally progressive curvature distributions are set to the semi-mathematical expression for a free-form surface, the surface point set can then be derived through numerical integration. This is then converted to a NURBS surface while retaining the surface curvature. Then, reflective scenes from the driving environment can be virtually realized using photorealistic ray tracing, in order to evaluate how these reflected images would appear to drivers.

Newly designed, fully covered metal stents for endoscopic ultrasound (EUS)-guided transmural drainage of peripancreatic fluid collections: a prospective randomized study.

BACKGROUND AND STUDY AIMS: Peripancreatic fluid collections (PFCs) have been adequately drained using multiple plastic stents placed in a single-step endoscopic ultrasound (EUS) procedure. Recent reports have presented the usefulness of metal stents for this procedure; however, there has been no prospective comparative study on their effectiveness and safety. We conducted a prospective randomized study to compare multiple plastic stents with fully covered, self-expanding metal stents (FCSEMSs) for the drainage of PFCs. PATIENTS AND METHODS: Between January 2012 and May 2013, patients with PFCs demonstrated by various modalities were enrolled in our study. Patients were randomly assigned to receive either a FCSEMS or plastic stents for EUS-guided PFC drainage. The procedure time, technical success rate, and adverse event rates of the PFCs were evaluated. RESULTS: 50 patients (41 men) were included and randomly assigned to either the FCSEMS group (n = 25) or the plastic stent group (n = 25). The median procedure time with FCSEMS was significantly shorter than with plastic stents (15.0 min vs. 29.5 min, P < 0.01). The technical success rate was 100 % for both groups. The clinical success rate was 20 out of 23 for FCSEMS and 20 out of 22 for plastic stents (P = 0.97). No adverse events occurred in the FCSEMS group, while adverse events occurred in two patients in the plastic stent group (P = 0.16). One recurrence was observed during follow-up in the FCSEMS group and none in the plastic stent group (P = 0.15). CONCLUSIONS: EUS-guided PFC drainage with FCSEMSs is comparable to such drainage with plastic stents in terms of technical feasibility, efficacy, and safety; however, the use of FCSEMSs may also simplify and shorten the procedure. CLINICAL TRIAL REGISTRATION: KCT0000766 (https://cris.nih.go.kr).

Surface plasmon resonance enhanced organic light emitting diode.

Surface plasmonic structure in solution-processable PHOLED was fabricated by blending and spin-coating techniques. ZnO nanoparticles were incorporated into the hole injection layer (PEDOT:PSS) by mixing solutions prior the EML spin-coating. The device structure are ITO/PEDOT:PSS+ ZnO/FIrpic:PVK/BCP/Alq3/LiF/Al. Plasmonic structures in PHOLED can be used for the enhancement of performance in existing device architectures.

[Safety and effectiveness of successive extracorporeal shock wave lithotripsy for pancreatolithiasis under intravenous bolus pethidine administration alone].

BACKGROUND/AIMS: A retrospective analysis was performed to evaluate the safety and effectiveness of extracorporeal shock wave lithotripsy (ESWL) for pancreatolithiasis on successive days under intravenous bolus of pethidine alone. METHODS: Ninety patients with calcified pancreatic stones (≥5 mm) presenting with abdominal pain were selected for ESWL. ESWL was performed with an electroconductive lithotripter under fluoroscopic target systems. Fragmented calculi after ESWL were removed by endotherapy. RESULTS: A mean of 4.2 ESWL sessions were performed for each patient, with a mean of 2,984 shocks at a mean power setting of 12.8 kV. Eighty-four (89.3%) patients underwent ESWL for three or more days in a row. Fragmentation of the stones were achieved in 83/90 (92.2%) patients. Complete clearance of the main pancreatic duct was achieved in 54/90 (60.0%) patients, and partial clearance was achieved in 27 (30.0%) patients. The mean dose of pethidine used during ESWL was 53.5±20.7 mg per session. As ESWL-related complications, four (4.3%) patients developed mild acute pancreatitis. CONCLUSIONS: In case of endoscopically difficult-to-treat pancreatic duct stones, combined therapy with ESWL is an effective method, and treatment with multiple sessions of ESWL on successive days under intravenous bolus of pethidine alone is safe and well tolerated.

[Synchronous malignant intraductal papillary mucinous neoplasms of the bile duct and pancreas requiring left hepatectomy and total pancreatectomy].

Intraductal papillary mucinous neoplasm of the bile duct (IPMN-B) and intraductal papillary mucinous neoplasm of the pancreas (IPMN-P) have striking similarities and are recognized as counterparts. However, simultaneous occurrence of IPMN-B and IPMN-P is extremely rare. A 66 year-old female presented with recurrent epigastric pain and fever. During the past 9 years, she had three clinical episodes related to intrahepatic duct stones and IPMN-P in the pancreas head and was managed by medical treatment. Laboratory test results at admission revealed leukocytosis (12,600/mm(3)) and elevated CA 19-9 level (1,200 U/mL). Imaging study demonstrated liver abscess in the Couinaud's segment 4, IPMN-B in the left lobe, and IPMN-P in the whole pancreas with suspicious malignant change. Liver abscess was drained preoperatively, followed by left lobectomy with bile duct resection and total pancreatectomy with splenectomy. On histologic examination, non-invasive intraductal papillary mucinous carcinoma arising from various degree of dysplastic mucosa of the liver and pancreas could be observed. However, there was no continuity between the hepatic and pancreatic lesions. This finding in our case supports the theory that double primary lesions are more likely explained by a diffuse IPMN leading to synchronous tumors arising from both biliary and pancreatic ducts rather than by a metastatic process. Herein we present a case of simultaneous IPMN of the bile duct and pancreas which was successfully treated by surgical management.

Synthesis and characterization of poly(vinylpyrrolidone)-capped silicon-nanoparticles.

Polymer-capped silicon nanoparticles (Si NPs) were prepared using poly(vinylpyrrolidone) (PVP) as a protection layer to minimize the surface oxidation of the surface. The wet synthetic procedure were performed at room temperature via a one-pot synthesis. The PVP capped Si-NPs were characterized by thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM). HR-TEM micrograms confirm the presence of crystalline Si-NPs. The pattern by Selected Area Electron Diffraction (SAED) reveals (111), (220) lattice planes which are consistent with the cubic-structured crystalline silicon. The mean size of Si-NPs is estimated to be ca. 10 nm, which is larger than those from conventional wet synthetic methods for silicon quantum dots.

Structural modification of fluorene-thiophene-based copolymers for OPVs.

A series of fluorene-thiophene-based pi-conjugated copolymers, PFT2, PFT4, and PFT2BP, have been synthesized using the Suzuki coupling reaction. Compared to PFT2 and PFT2BP, PFT4 film showed clearly red-shifted UV-visible absorption and photoluminescence (PL) spectra with maxima at 474 and 597 nm, respectively. The optical and electrochemical properties of copolymers could be tuned by changing conjugation lengths of comonomer units from bithiophene (PFT2) to quaterthiophene (PFT4). Moreover, PFT4 containing quaterthiophene showed relatively lower optical band gap of 2.16 eV. The organic photovoltaic cells (OPVs) were fabricated using the copolymers as donor with a sandwich configuration of ITO/PEDOT:PSS/copolymer:PC71BM/LiF/Al. PFT4 showed the best device performance with the optimized power conversion efficiency (PCE) of 2.26% (J(SC) = 7.67 mA/cm2, V(OC) = 0.81 V, FF = 0.36). The higher OPV performance of PFT4 can be explained by its relatively low energy band gap and improved UV absorption property.

Clinical characteristics of intraductal papillary mucinous neoplasm manifesting as acute pancreatitis or acute recurrent pancreatitis.

BACKGROUND AND AIM: Comparatively little is known about acute pancreatitis or acute recurrent pancreatitis (AP/ARP) with intraductal papillary mucinous neoplasm of the pancreas (IPMN) as the causative lesion although there have been many reports about the malignant potential of IPMN as a premalignant lesion. METHODS: From 2000 to 2008, in a single tertiary referral center, out of 784 patients coded by the International Classification of Disease-10 with IPMN, 489 patients fulfilled our diagnostic criteria of IPMN. After careful exclusion of all known causes of AP/ARP, 34 patients with IPMN as the cause of AP/ARP were enrolled. RESULTS: AP/ARP caused by IPMN occurred in 34 (7%) out of 488 patients with IPMN, and the prevalence rate of AP/ARP was higher in the main-duct/combined type than in the branch-duct type (14% [16/111] vs 5% [18/378], respectively, P = 0.002). The severity of pancreatitis was mild, based on the computed tomography severity index score (median 2, range 0-4). Histologic review of 24 patients with surgical resection revealed four adenomas (17%), 17 borderline malignancies (71%), two carcinomas in situ (8%), and one invasive carcinoma (4%). AP/ARP did not recur in any of the 24 surgically resected patients during the follow-up period (median 52 months, range 38-115 months). CONCLUSIONS: AP/ARP caused by IPMN was of infrequent occurrence. AP/ARP caused by IPMN occurred more frequently in the main-duct/combined type than in the branch-duct type. Most cases were mild in severity and benign in histopathology. AP/ARP can be an initial manifestation of IPMN, though uncommon, which leads to diagnosis.

Spontaneous rupture of intrahepatic bile duct following portal vein embolization in a patient with perihilar cholangiocarcinoma: a case of successful curative resection.

We herein present a case of spontaneous rupture of intrahepatic bile duct in a patient with perihilar cholangiocarcinoma, which were successfully treated by curative resection. A 60-year-old male patient with perihilar cholangiocarcinoma was decompressed with single percutaneous transhepatic biliary drainage. Two days after right portal vein embolization, the patient suffered from paralytic ileus with marked abdominal distension. Imaging study revealed that marked fluid collection around the liver and whole abdomen, suggesting intrahepatic bile duct rupture. With abdominal drainage and biliary decompression for 2 weeks, the biliary rupture was controlled. To enhance the safety of right hepatectomy, additional right hepatic vein embolization was performed. The patient underwent routine surgical procedures for right hepatectomy, caudate lobectomy and bile duct resection, and recovered uneventfully and discharged 18 days after surgery. This is the first report of a case of spontaneous rupture of intrahepatic bile duct in a patient with perihilar cholangiocarcinoma.

EUS-guided radiofrequency ablation of the porcine pancreas.

BACKGROUND: EUS-guided radiofrequency ablation (EUS-RFA) could be used as an adjunct and effective alternative mode of treatment for unresectable locally advanced and nonmetastatic pancreatic adenocarcinoma. However, its translation into clinical practice has been restricted because of limited data and high procedure-related risk. OBJECTIVE: To evaluate the feasibility, efficacy, and safety of EUS-RFA in the normal porcine pancreas. DESIGN: Prospective, endoscopic, experimental study in a porcine model. SETTING: Tertiary-care referral center animal laboratory. PATIENTS: Animal study. INTERVENTION: EUS-RFA of the pancreas was attempted on 10 adult mini pigs. An 18-gauge endoscopic RFA electrode was used to puncture the body and tail of the pancreas, with an output power of 50 W for 5 minutes. MAIN OUTCOME MEASUREMENTS: The feasibility, efficacy, and safety of EUS-RFA. RESULTS: A spherical necrotic lesion surrounded by fibrous tissue localized in the pancreatic parenchyma was observed on histopathologic examination. The mean diameter of the ablated tissue was 23.0 ± 6.9 mm. No major procedure-related complications were noted, and all pigs survived without any distress behavioral pattern for 7 days until autopsy. LIMITATIONS: Small sample size with short-term observation and the lack of evaluation of the head of the pancreas. CONCLUSION: EUS-RFA of the pancreatic body and tail was feasible, effective, and relatively safe in a porcine model. More animal studies to assess damage to adjacent organs are required before human trials can be conducted.