Flexible and freestanding core-shell SnO_<i>x</i>/carbon nanofiber mats for high-performance supercapacitors

Samuel, Edmund,Joshi, Bhavana,Jo, Hong Seok,Kim, Yong Il,Swihart, Mark T.,Yun, Je Moon,Kim, Kwang Ho,Yoon, Sam S. ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.728 No.-

<P><B>Abstract</B></P> <P>We demonstrate the fabrication of core-shell SnO<SUB> <I>x</I> </SUB>/carbon nanofiber (CNF) composite mats via single-nozzle one-step electrospinning for use as flexible freestanding electrodes in supercapacitors. The freestanding and flexible nature of the composites is essential for their use in lightweight, portable, and foldable electronic devices and eliminates the need for a separate current collector. We fully characterized the structural and morphological properties of the SnO<SUB> <I>x</I> </SUB>/CNF mats and optimized the SnO<SUB> <I>x</I> </SUB> to CNF precursor ratio. The optimized SnO<SUB> <I>x</I> </SUB>/CNF-based symmetric supercapacitor exhibited a capacitance of 289 F·g<SUP>−1</SUP> at a scan rate of 10 mV·s<SUP>−1</SUP>. Moreover, it retained more than 88% of its initial capacitance after 5000 cycles, highlighting the long-term stability of supercapacitors based on these SnO<SUB> <I>x</I> </SUB>/CNF mats.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A core-shell-structured SnO<SUB>x</SUB>/CNF composite mat electrodes were synthesized by single-nozzle-electrospinning. </LI> <LI> The core-shell composite is highly flexible and freestanding. </LI> <LI> Capacitors using these electrodes had specific capacitance of up to 289 F·g<SUP>−1</SUP> at a scan rate of 10 mV·s<SUP>−1</SUP>. </LI> <LI> Specific capacitance at a current density of 100 mA·g<SUP>−1</SUP> reached 273 F·g<SUP>−1</SUP>. </LI> </UL> </P>

High-performance supercapacitors using flexible and freestanding MnO_x/carbamide carbon nanofibers

Samuel, Edmund,Jo, Hong Seok,Joshi, Bhavana,Park, Hyun Goo,Kim, Yong Il,An, Seongpil,Swihart, Mark T.,Yun, Je Moon,Kim, Kwang Ho,Yoon, Sam S. Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.423 No.-

<P><B>Abstract</B></P> <P>We demonstrate the fabrication of a MnO<I> <SUB>x</SUB> </I>/carbamide carbon nanofiber (CCNF) composite consisting of MnO particles embedded in CCNFs as a highly flexible and freestanding electrode material for supercapacitors. A sacrificial polymer component, polymethylmethacrylate, included in the precursor solution, pyrolyzes during heating, resulting in pores in the fibers, some of which are filled by the MnO nanocrystals. Carbamide is added to control the size of the MnO<I> <SUB>x</SUB> </I> particles as well as to increase the carbon content of the composite and hence its conductivity. The X-ray diffraction and Raman spectra of the composite show that the MnO particles formed have low crystallinity. Transmission electron microscopy confirms that the MnO particles are distributed very uniformly over the CCNFs. Symmetric supercapacitors constructed using electrodes of this composite exhibit specific capacitances of 498F∙g<SUP>−1</SUP> at a scan rate of 10mV∙s<SUP>−1</SUP> and 271F∙g<SUP>−1</SUP> at a current density of 1A∙g<SUP>−1</SUP>. They also exhibit excellent long-term cycling performance, retaining 93% of their initial capacity after 5000 cycles of galvanostatic charging/discharging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We successfully fabricated a novel flexible MnO/CCNF composite. </LI> <LI> Flexible MnO/CCNF showed excellent retention (93%) after 5000 cycles at 1Ag<SUP>−1</SUP>. </LI> <LI> MnO/CCNF composite demonstrated specific capacitance of 498Fg<SUP>−1</SUP> at a scan rate of 10mVs<SUP>−1</SUP>. </LI> <LI> Dynamic MnO particle formation controlled by using carbamide. </LI> </UL> </P>

Carbon nanofibers decorated with FeO<i> _x </i> nanoparticles as a flexible electrode material for symmetric supercapacitors

Samuel, Edmund,Joshi, Bhavana,Jo, Hong Seok,Kim, Yong Il,An, Seongpil,Swihart, Mark T.,Yun, Je Moon,Kim, Kwang Ho,Yoon, Sam S. Elsevier 2017 Chemical Engineering Journal Vol. No.

<P><B>Abstract</B></P> <P>We have produced flexible, freestanding, and light weight mats of FeO<I> <SUB>x</SUB> </I>-decorated carbon nanofibers (CNFs) and demonstrated their use in supercapacitors with high energy and power density and excellent long term capacitance retention. Highly flexible carbon-iron oxide nanofibers were synthesized by electrospinning a solution of polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), and iron acetylacetonate (FeAcAc), followed by annealing to carbonize the PAN, pyrolyze the PMMA to produce pores, and convert FeAcAc to FeO nanoparticles. The morphology of the FeO<I> <SUB>x</SUB> </I>/CNF composite was determined by scanning and transmission electron microscopies, which showed that the embedded FeO<I> <SUB>x</SUB> </I> nanoparticles were well distributed in the CNF electrode. We employed cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy to evaluate the electrochemical performance of symmetric supercapacitors prepared from the FeO<I> <SUB>x</SUB> </I>/CNF composite. The supercapacitors exhibited high specific capacitance (427F·g<SUP>−1</SUP> at 10mV·s<SUP>−1</SUP> and 436F·g<SUP>−1</SUP> at 1A·g<SUP>−1</SUP> in the optimal case) and good stability, retaining 89% of their initial capacitance after 5000 cycles at a current density of 1A·g<SUP>−1</SUP>. The optimal device achieved an energy density of 167Wh·kg<SUP>−1</SUP> at a power density of 0.75kW·kg<SUP>−1</SUP>, and an energy density of 66Wh·kg<SUP>−1</SUP> at a power density of 7.5kW·kg<SUP>−1</SUP>. These combinations of energy and power densities can meet the needs of many emerging supercapacitor applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly flexible FeO<SUB>x</SUB>-carbon nanocomposite nanofibers were fabricated. </LI> <LI> Freestanding FeO<I> <SUB>x</SUB> </I>-CNF showed excellent retention (89%) after 5000 cycles at 1A·g<SUP>−1</SUP>. </LI> <LI> A FeO<SUB>x</SUB>/CNF-based supercapacitor provides 436F·g<SUP>−1</SUP> of capacitance at 1A·g<SUP>−1</SUP>. </LI> <LI> Excellent uniform decoration of CNF with FeO<SUB>x</SUB> was demonstrated. </LI> </UL> </P>

Intracorporeal versus extracorporeal anastomosis in laparoscopic right hemicolectomy: a retrospective cohort study of anastomotic complications

Frigault Jonathan,Avoine Samuel,Drolet Sébastien,Letarte François,Bouchard Alexandre,Gagné Jean-Pierre,Thibault Claude,Grégoire Roger C.,Bouthillette Naomee Jutras,Gosselin Maude,Bouchard Philippe 대한대장항문학회 2023 Annals of Coloproctolgy Vol.39 No.2

Purpose: Laparoscopic right hemicolectomy (LRH) can be performed with an intracorporeal anastomosis (IA) or extracorporeal anastomosis (EA). It is not clear which technique is best. This study evaluated the impact of each anastomosis technique on perioperative safety and postoperative evolution. Methods: We performed a retrospective study at a tertiary colorectal surgery center. All patients who had an elective LRH from 2015 to 2019 were analyzed according to the anastomosis technique used. Results: In total, 285 patients were included in the study. IA was performed in 64 patients (22.5%). Mean operative time was longer in the patients with IA (IA, 160±31 minutes vs. EA, 138±42 minutes; P<0.001). No differences were observed in intraoperative complications, time to first bowel movement, length of stay, reoperation, or rehospitalization. Time to first flatus was longer in the patients with IA (P=0.049). At 30 days after surgery, there were no differences in the frequency of anastomotic leak (IA, 0% vs. EA, 2.3%; P=0.59), bleeding (IA, 3.1% vs. EA, 2.7%; P>0.99), or intraabdominal abscess (IA, 0% vs. EA, 0.5%; P>0.99). During follow-up, we noted more incisional hernias in patients with EA (IA, 1.6% vs. EA, 11.3%; P=0.01) and a trend toward more hernia in patients with EA in multivariate analysis (hazard ratio, 7.13; P=0.06). Anastomosis technique had no influence on recurrence. Conclusion: For LRH, both IA and EA are safe, with a low incidence of complications when performed by experienced surgeons. IA may be associated with a lower incidence of incisional hernia.

In Vitro Antibacterial, Phototoxic, and Synergistic Activity of Ethanol Extracts from Costus cf. arabicus L.

Francisco A.B. Cunha,Edinardo F.F. Matias,Samuel V. Brito,Felipe S. Ferreira,João Marcelo A. Braga,José G.M. Costa,Henrique D.M. Coutinho 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.9

In this study, ethanol extracts of stems and leaves of Costus cf. arabicus L. were evaluated for antibacterial activity against multidrug-resistant strains of Escherichia coli and Staphylococcus aureus. The antibacterial and modulatory activities of the extracts were assayed by microdilution. The light-enhanced antibacterial activity was assayed by a light regimen. The growth of the bacteria tested was not inhibited by the extracts. The minimum inhibitory concentration values were ≥1,024 μg/mL. However, the antibiotic activity of aminoglycosides was synergistically enhanced when these extracts at subinhibitory concentrations were combined with the antibiotics. Also, both extracts showed activity against the wild-type bacterial strains, but the leaf extract was the more active extract, being active against both S. aureus and E. coli. Therefore, we conclude that the ethanol extracts of stems and leaves of C. cf. arabicus L. have potential light-induced antibacterial activity and synergistic antibiotic activity. This study showed that these extracts may be a promising source of antibacterial and modulatory agents.

Damping index of Doppler hepatic vein waveform to assess the severity of portal hypertension and response to propranolol in liver cirrhosis: a prospective nonrandomized study

Kim, Moon Young,Baik, Soon Koo,Park, Dong Hun,Lim, Dae Wook,Kim, Jae Woo,Kim, Hyun Soo,Kwon, Sang Ok,Kim, Young Ju,Chang, Sei Jin,Lee, Samuel S. Wiley-Blackwell Publishing 2007 Liver International Vol. No.

<P>Abstract</P><P>Background and Aims</P><P>Alterations in the Doppler hepatic vein (HV) waveform are associated with cirrhosis and portal hypertension. We prospectively evaluated the correlation between the extent of abnormal Doppler HV waveforms expressed as damping index (DI) and the hepatic venous pressure gradient (HVPG) and response to propranolol in patients with cirrhosis.</P><P>Material and Methods</P><P>In 76 patients with cirrhosis (69 men and seven women), both DI of Doppler HV waveform and HVPG were measured, and the relationship between them was analysed. DI was calculated by the minimum velocity/maximum velocity of the HV waveform. An HVPG>12 mmHg was defined as severe portal hypertension. In a subgroup of 19 patients receiving propranolol, changes in both DI and HVPG were evaluated after propranolol administration for 3 months. One author (S. K. B.) performed all DI of Doppler HV waveform studies.</P><P>Results</P><P>Abnormal HV waveforms were seen in 66 of 76 patients (86.8%). DI significantly correlated with the grade of HVPG, i.e. with higher HVPG increased DI was observed (<I>P</I><0.01). By logistic regression analysis, DI>0.6 was significantly more likely to be severe portal hypertension (odds ratio: 14.19, 95% confidence interval: 4.07–49.55). Receiver-operating characteristic curve according to the value of 0.6 of DI showed a sensitivity of 75.9% and a specificity of 81.8% for the presence of severe portal hypertension. In 19 patients of the propranolol subgroup, change of DI following propranolol treatment also significantly correlated with that of HVPG (<I>P</I><0.01).</P><P>Conclusions</P><P>Damping index of the HV waveform by Doppler ultrasonography might be a non-invasive supplementary tool in evaluating the severity of portal hypertension and in responding to propranolol in patients with liver cirrhosis.</P>

Natural products in the research of cholesterol gallstones

Ibrahim Guillermo Castro-Torres,Minarda De la O-Arciniega,Janeth Gallegos-Estudillo,Mariano Martínez-Vázquez,Elia Brosla Naranjo-Rodríguez,Miguel Ángel Domínguez-Ortíz,Jesús Samuel Cruz-Sánchez 셀메드 세포교정의약학회 2013 TANG Vol.3 No.3

Cholesterol gallstones are a digestive disease of high prevalence that has many risk factors; for this reason, research has focused mainly on how to prevent it rather than how to treat it. Many molecules of the hepatic, bile and intestinal systems are involved in the pathophysiology of this disease, making it very difficult to find a therapeutic target. The pharmacological treatment is limited, so when gallstones generate symptoms, medical treatment indicates gallbladder removal. Ursodeoxycholic acid is used to dissolve cholesterol stones, and ezetimibe and statins are other drugs with possible applications in the treatment of this disease. Given the small number of drugs that have been developed for treating this disease, the research of natural products becomes of paramount importance. Resources such as black radish, glucosinolates, fenugreek, capsaicin, curcumin, garlic, and onion, have all shown significant effects in the prevention and treatment of cholesterol gallstones. In this review, we made a synthesis of the scientific reports that deal with these natural products and that can serve as antecedents for finding a way to treat the most common disease of the gallbladder.

Nationalism and Globalization in South Korea’s Foreign Policy

Samuel S,Kim 신아시아연구소(구 신아세아질서연구회) 2007 신아세아 Vol.14 No.3

An examination of Korea’s foreign policy in the post-Cold War era quickly encounters a double paradox: globalization and nationalism. This paper provides an analysis and assessment of how Korea is coping with these twin pressures of globalization from without and above and nationalism from within and below, with a particular focus on the dynamics of national identity. A consideration of the interplay between national identity and globalization may develop an alternative conceptual framework to facilitate a synthetic interactive explanation of the thinking and practice of globalization in post-Cold War Korean foreign policy. Globalization as a political strategy developed from Kim Young Sam’s segyehwa drive through Kim Dae June’s “intormationization” to Roh Moo-hyun’s FTA drive. These policy themes then played out in the appropriation of globalization for national-identity purposes, especially in relation to the great powers of Northeast Asia. The nexus of globalization and national identity can be seen particularly in Korea’s relations with Japan, China, and the United States. In the end, Korea’s growing integration into the regional and global systems, aided and abetted by the forces of globalization, has a paradoxical relationship with nationalism, as both remain moving targets that force Korea to adapt to the changing circumstances of Korea’s nationalized and globalized “intermestic politics.”

CHINA’S CONFLICT-MANAGEMENT APPROACH TO THE NUCLEAR STANDOFF ON THE KOREAN PENINSULA

Samuel S. Kim 경남대학교 극동문제연구소 2006 ASIAN PERSPECTIVE Vol.30 No.1

This article provides an analysis and assessment of China’s uncharacteristically proactive conflict-management (CM) diplomacy in the U.S.-North Korea (DPRK) nuclear standoff on the Korean peninsula from 2002 to 2005. In the first of four sections, the focus is on the global context and conditions that gave rise to CM studies as a new field of international relations research in the West. The second section argues that three proximate and underlying causes—greater danger, greater stakes, and greater leverage—catapulted Beijing into the terra incognita of CM leadership role. The third section examines the shift in China’s role as well as the style and substance of this approach. The fourth section critically evaluates the possibilities and limitations of China’s conflict-management diplomacy for the resolution of the U.S.-DPRK nuclear standoff. The conclusion is a brief assessment of future prospects for establishing a more peaceful and prosperous regional order in Northeast Asia either through the ongoing Six Party Talks or through some permanent Northeast Asian security regime coming out of the success or failure of the six-party process.

CHINA'S PATH TO GREAT POWER STATUS IN THE GLOBALIZATION ERA

Kim, Samuel S. 경남대학교 극동문제연구소 2003 ASIAN PERSPECTIVE Vol.27 No.1

Not since the debate in the mid-1960s over containment with or without isolation have the implications of rising Chinese power been so pervasive and controversial as in recent years. This article joins the debate by tracking and explaining China's path to great power status in the post-cold war era of globalization. Globalization has greatly influenced not only the dynamics of power on the world stage but also the very meaning of power. While external assessments. of the significance of a rising China vary considerably depending on normative or theoretical perspective, China's own conceptualization and assessment have come to focus more on economic, scientific, and technological than military factors. As China is increasingly integrated into the world community, how it wields whatever power it holds determines in the end the character of its international influence.