Thermally Healable and Recyclable Graphene-Nanoplate/Epoxy Composites Via an In-Situ Diels-Alder Reaction on the Graphene-Nanoplate Surface.

In this work, thermally healable graphene-nanoplate/epoxy (GNP/EP) nanocomposites were investigated. GNPs were used as reinforcement and crosslinking platforms for the diglycidyl ether of bisphenol A-based epoxy resin (DGEBA) through the Diels-Alder (DA) reaction with furfurylamine (FA). The GNPs and FA could then be used as a derivative of diene and dienophile in the DA reaction. It was expected that the combination of GNPs and FA in DGEBA would produce composites based on the interfacial properties of the components. We confirmed the DA reaction of GNPs and FA at the interface during curing of the GNP/EP nanocomposites. This procedure is simple and solvent-free. DA and retro DA reactions of the obtained composites were demonstrated, and the thermal healing properties were evaluated. The behavior of the GNP/EP nanocomposites in the DA reaction is similar to that of thermosetting polymers at low temperatures due to crosslinking by the DA reaction, and the nanocomposites can be recycled by a retro DA reaction at high temperatures.

Thermally Self-Healing Graphene-Nanoplate/Polyurethane Nanocomposites via Diels⁻Alder Reaction through a One-Shot Process.

Thermally self-healing graphene-nanoplate/polyurethane (GNP/PU) nanocomposites were prepared via a bulk in-situ Diels⁻Alder (DA) reaction. Graphene-nanoplate (GNP) was used as a reinforcement and crosslinking platform by a DA reaction with a furfuryl-based chain extender of polyurethane (PU). Results showed that a DA reaction occurred in GNP during the PU forming cure process. This procedure is simple and solvent free because of the absence of any independent surface modification process. Through the calculation of the interfacial tensions, the conditions of the bulk in-situ DA reaction were determined to ensure that GNP and the furfuryl group can react with each other at the interface during the curing process without a solvent. The prepared composites were characterized in terms of thermal, mechanical, and thermally self-healing properties via the DA reaction. In the PU capable of a DA reaction (DPU), characteristic peaks of DA and retro DA reactions were observed in the Fourier transform infrared (FT-IR) spectroscopy and endothermic peaks of retro DA reactions appeared in differential scanning calorimetry (DSC) thermograms. The DPU showed significantly enhanced physical properties and chemical resistance. The thermally self-healing capability was confirmed at 110 °C via the retro DA reactions. It is inferred that thermally self-healable crosslinked GNP/PU nanocomposites via DA reactions could be prepared in a simple bulk process through the molecular design of a chain extender for the in-situ reaction at the interface.

Large Improvement in the Mechanical Properties of Polyurethane Nanocomposites Based on a Highly Concentrated Graphite Nanoplate/Polyol Masterbatch.

In this study, a highly concentrated graphite nanoplate (GNP)/polyol masterbatch was prepared by the exfoliation of natural graphite in an aqueous system using cetyltrimethylammonium bromide and the replacement of aqueous solution with a polyol, viz. poly(tetramethylene ether glycol), and it was subsequently used to prepare polyurethane (PU) nanocomposites by simple dilution. The polyol in the masterbatch efficiently prevented the aggregation of GNPs during the preparation of PU nanocomposite. In addition, the dispersed GNPs in the masterbatch exhibited rheological behavior of lyotropic liquid crystalline materials. In this study, the manufacture and application methods of the GNP/polyol masterbatch were discussed, enabling the facile manufacture of the PU/GNP nanocomposites with excellent mechanical properties. In addition, the manner in which the GNP alignment affected the microphase separation of PU in the nanocomposites was investigated, which determined the improvement in the mechanical properties of the nanocomposites. High-performance PU/GNP nanocomposites are thought to be manufactured from the GNP/polyol masterbatch by the simple dilution to 0.1 wt% GNP in the nanocomposite.

Evaluating the Minimal Specimens From Endoscopic Ultrasound-Guided Fine-Needle Aspiration in Pancreatic Masses.

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has become one of the most useful diagnostic modalities for the diagnosis of pancreatic mass. The aim of this study was to investigate the role of analyzing the minimal specimens obtained by EUS-FNA for the diagnosis of solid masses of pancreas.This study consisted of retrospective and prospective analyses. The retrospective study was performed on 116 patients who underwent EUS-FNA of solid masses for cytological smear, histological analysis, and combined analysis including immunohistochemical (IHC) staining. In the prospective study, 79 patients were enrolled to evaluate the quality and accuracy of EUS-FNA histological analysis and feasibility of IHC staining.The final diagnoses of all patients included pancreatic cancer (n = 126), nonpancreatic cancer (n = 21), other neoplasm (n = 27), and benign lesions (n = 21). In our retrospective study, the combined analysis was more sensitive than cytological analysis alone (P < 0.01). The overall sensitivity of cytology, histology, and combined analysis was 69.8%, 67.2%, and 81.8%, respectively. In the prospective analysis, 64.2% of all punctures were helpful for determining the diagnosis and 40.7% provided sufficient tissue for IHC staining. Histological analysis was helpful for diagnosis in 74.7% of patients. IHC staining was necessary for a definite diagnosis in 11.4% of patients, especially in the cases of nonmalignant pancreatic mass.Histological analysis and IHC study of EUS-FNA specimens was useful for the accurate diagnosis of pancreatic and peripancreatic lesions. Combined analysis showed significantly higher sensitivity than cytology alone because IHC staining was helpful for a diagnosis in some patients.

[A Case of Intra-abdominal Paragonimiasis Mimicking Metastasis of Lung Cancer Diagnosed by Endoscopic Ultrasound-guided Fine Needle Aspiration].

Paragonimiasis has been continuously decreasing in Korea. However, it still occurs by ingesting raw or incompletely cooked fresh water crab or crayfish. The diagnosis of paragonimiasis is challenging because of its rarity. It may be confused with other inflammatory disease or carcinomatosis. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has lower risk of complications such as bleeding, perforation than percutaneous fine needle aspiration. EUS-FNA is more accurate and popular method to find mucosal or submucosal tumors and the lesions of several organs. Benign and malignant tumors, infectious diseases have been diagnosed by EUS-FNA, but there was no report describing the use of EUS-FNA for diagnosing paragonimiasis. Herein, we present a 47-year-old male patient with paragonimiasis diagnosed by EUS-FNA. Imaging studies revealed mass lesions in the lung and peritoneal cavity, which was eventually confirmed as paragonimiasis using EUS-FNA.

Prevalence of and risk factors for gastrointestinal diseases in korean americans and native koreans undergoing screening endoscopy.

BACKGROUND/AIMS: In South Korea, health check-ups are readily accessible to the public. We aimed to compare the prevalence of upper gastrointestinal (GI) and lower GI diseases in Korean Americans and native Koreans to determine differences and risk factors. METHODS: In total, 1,942 subjects who visited Gangnam Severance Hospital from July 2008 to November 2010 for a health check-up were enrolled. Basic characteristics and laboratory data for the subjects were collected. Esophagogastroduodenoscopy and colonoscopy were performed. In total, 940 Korean Americans (group 1) and 1,002 native Koreans (group 2) were enrolled. RESULTS: The overall prevalence of GI diseases for each group (group 1 vs group 2) were as follows: reflux esophagitis (RE) (9.65% vs 7.9%), gastric ulcer (2.8% vs 3.4%), duodenal ulcer (2.3% vs 3.6%), gastric cancer (0.4% vs 0.3%), colorectal polyp (35.9% vs 35.6%), colorectal cancer (0.5% vs 0.5%), and hemorrhoids (29.4% vs 21.3%). The prevalence of hemorrhoids was significantly higher in group 1 than in group 2 (p=0.001). In the multivariable analysis of group 1, male sex, age over 50 years, hypercholesterolemia and hypertriglyceridemia predicted colorectal polyps. Male sex and high fasting glucose levels were associated with RE. CONCLUSIONS: Our study showed that the prevalence of GI diseases (except hemorrhoids) in Korean Americans was similar to that observed in native Koreans. Therefore, the Korean guidelines for upper and lower screening endoscopy may be applicable to Korean Americans.

[Prevalence and risk factors of colorectal adenoma in 14,932 koreans undergoing screening colonoscopy].

BACKGROUND/AIMS: Current international guidelines recommend colorectal cancer screening for average-risk people over 50 years of age. Accordingly, we aimed to estimate the prevalence of colorectal neoplasms in all age groups and evaluate associated risk factors. METHODS: Data of 14,932 subjects who underwent colonoscopy from July 2006 to January 2012 at Health Promotion Center, Gangnam Severance Hospital (Seoul, Korea) as part of a health check-up were reviewed retrospectively. RESULTS: The overall prevalence of colorectal neoplasms and adenoma were 34.6% and 25.3%, respectively. Colorectal adenoma was found in 3.2%, 13.0%, 21.7%, 33.8%, 44.0%, 50.5%, and 54.2% of subjects under 30 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years, 70-79 years, and over 80 years of age (trend p<0.0001). Independent predictors of colorectal adenoma included male gender (OR 2.38, 95% CI 2.084-2.718), positive occult blood (2.266, 1.761-2.917), positive serology of Helicobacter pylori (1.253, 1.114-1.409) and hypertriglyceremia (1.267, 1.065-1.508). Compared to the 30-39 years of age reference group, the ORs for each age group were 0.195 (under 30 years), 1.634 (40-49 years), 2.954 (50-59 years), 5.159 (60-69 years), 5.640 (70-79 years), 11.020 (over 80 years), while the 95% CIs were 0.071-0.536 (under 30 years), 1.340-1.992 (40-49 years), 2.421-3.604 (50-59 years), 4.109-6.476 (60-69 years), 3.822-8.322 (70-79 years), and 2.809-42.234 (over 80 years). CONCLUSIONS: Colorectal adenoma prevalence increased proportionally with age. Only subjects under the age of 30 years had a definitely lower prevalence of colorectal adenoma. Male gender, positive occult blood, positive serology of H. pylori, and hypertriglyceremia were associated risk factors of colorectal adenoma.

The value of positron emission tomography/computed tomography for evaluating metastatic disease in patients with pancreatic cancer.

OBJECTIVES: Routine application of positron emission tomography/computed tomography (PET/CT) for pancreatic cancer staging remains a controversial approach. The purpose of this study was to reassess the clinical impact of PET/CT for the detection of distant metastasis of pancreatic cancer. METHODS: From January 2006 to June 2009, 125 patients with histologically proven pancreatic cancer that had undergone PET/CT at our hospital were retrospectively reviewed. To evaluate the clinical efficacy of PET/CT on the management plan, the post-PET/CT management plans were compared with the pre-PET/CT management plans. RESULTS: After the conventional staging workup, we determined that 76 patients (60.8%) had resectable lesions, whereas 48 patients had unresectable lesions. One patient underwent explorative laparotomy due to equivocal resectability. Positron emission tomography/computed tomography diagnosed distant metastasis in only 2 (2.6%) of the 76 patients with resectable lesions, and these patients did not undergo unnecessary surgical treatment. Complete resection was not performed in 8 of the 74 operative patients because they had distant metastasis detected during the operative procedure. Positron emission tomography/computed tomography diagnosed distant metastasis in 32 of the 44 patients with metastatic lesions that were histologically shown to have sensitivity of 72.7%. CONCLUSIONS: Positron emission tomography/computed tomography has a limited role in the evaluation of metastatic disease from pancreatic cancer.

[Clinical characteristics of autoimmune pancreatitis].

Korean autoimmune pancreatitis (AIP) criteria 2007 was aimed to diagnose the wide spectrum of AIP with high sensitivity. The most crucial issue when caring for patients with suspected AIP is to differentiate AIP from pancreatic cancer. Pancreatic cancer can be distinguished from AIP by pancreatic imaging, measurement of serum IgG4 levels, endoscopic ultrasound guided fine needle aspiration and trucut biopsy, and steroid trial. Autoimmune pancreatitis is a rare systemic fibroinflammatory disease which can affect not only the pancreas, but also a variety of organs such as the bile ducts, salivary glands, retroperitoneum, and lymph nodes. Organs affected by AIP have a lymphoplasmacytic infiltrate rich in IgG4-positive cells. This inflammatory process responds dramatically to oral steroid therapy. Granulocytic epithelial lesion (GEL) positive AIP patients differ from GEL negative AIP patients in clinical features such as equal gender ratio, younger mean age, no increase in serum IgG4, no association with extrapancreatic involvement, no relapse, and frequent association with inflammatory bowel disease. Further investigation is needed to clarify the pathogenic mechanisms including more definite serological markers for theses two entities.

Pancreatic tuberculosis masquerading as pancreatic serous cystadenoma.

Solitary pancreatic involvement of tuberculosis is rare, especially in an immunocompetent individual, and it may be misdiagnosed as pancreatic cystic neoplasms. Pancreatic cystic neoplasms are being identified in increasing numbers, probably because of the frequent use of radiology and advances in endoscopic techniques. However, they are composed of a variety of neoplasms with a wide range of malignant potential, and it is often difficult to differentiate pancreatic tuberculosis mimicking cystic neoplasms from benign or malignant pancreatic cystic neoplasms. Non-surgical diagnosis of pancreatic tuberculosis is inconclusive and continues to be a challenge in many cases. If so, then laparotomy should be employed to establish the diagnosis. Therefore, pancreatic tuberculosis should be kept in mind during the differential diagnosis of solitary cystic masses in the pancreas. We report a patient who had solitary pancreatic tuberculosis masquerading as pancreatic serous cystadenoma.