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Effect of soldering techniques and gapdistance on tensile strength of soldered Ni-Cr alloy joint
Lee, Sang-Yeob,Lee, Jong-Hyuk The Korean Academy of Prosthodonitics 2010 The Journal of Advanced Prosthodontics Vol.2 No.4
PURPOSE. The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. MATERIALS AND METHODS. Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. RESULTS. Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P < .05). CONCLUSION. There was no significant difference in ultimate tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm.
Lee Jisun,Jeong Woo Kyoung,김재훈,Kim Jong Man,Kim Tae Yeob,Choi Gyu Seong,Kwon Choon Hyuck David,Joh Jae-Won,Eom Sang-Yong 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.2
Objective: Muscle depletion in patients undergoing liver transplantation affects the recipients’ prognosis and therefore cannot be overlooked. We aimed to evaluate whether changes in muscle and fat mass during the preoperative period are associated with prognosis after deceased donor liver transplantation (DDLT). Materials and Methods: This study included 72 patients who underwent DDLT and serial computed tomography (CT) scans. Skeletal muscle index (SMI) and fat mass index (FMI) were calculated using the muscle and fat area in CT performed 1 year prior to surgery (1 yr Pre-LT), just before surgery (Pre-LT), and after transplantation (Post-LT). Simple aspects of serial changes in muscle and fat mass were analyzed during three measurement time points. The rate of preoperative changes in body composition parameters were calculated (preoperative ΔSMI [%] = [SMI at Pre-LT - SMI at 1 yr Pre-LT] / SMI at Pre-LT x 100; preoperative ΔFMI [%] = [FMI at Pre-LT - FMI at 1 yr Pre-LT] / FMI at Pre-LT x 100) and assessed for correlation with patient survival. Results: SMI significantly decreased during the preoperative period (mean preoperative ΔSMI, -13.04%, p < 0.001). In the multivariable analysis, preoperative ΔSMI (p = 0.016) and model for end-stage liver disease score (p = 0.011) were independent prognostic factors for overall survival. The mean survival time for patients with a threshold decrease in the preoperative ΔSMI (≤ -30%) was significantly shorter than for other patients (p = 0.007). Preoperative ΔFMI was not a prognostic factor but FMI increased during the postoperative period (p = 0.009) in all patients. Conclusion: A large reduction in preoperative SMI was significantly associated with reduced survival after DDLT. Therefore, changes in muscle mass during the preoperative period can be considered as a prognostic factor for survival after DDLT.
Lee, Joon Yeob,Hong, Won-Hwa,Kim, Woong,Park, Sung Hyuk,Jo, Wan-Kuen Pergamon Press 2017 Materials research bulletin Vol.94 No.-
<P><B>Abstract</B></P> <P>This study explores the photocatalytic performance of novel N and Fe dual-doped, one-dimensional TiO<SUB>2</SUB> nanotube structures (N–Fe–TNTs) for the degradation of α-pinene and toluene under visible-light illumination. N–Fe–TNTs were synthesized using a combination of sonochemical-hydrothermal-impregnation processes. N–Fe–TNT hybrids showed higher photocatalytic efficiency compared to pure TNT, N-doped TNT, and Fe-doped TNT. Specifically, the average decomposition efficiencies for α-pinene and toluene over N–Fe–TNT-1.0 were 94.6% and 88.7%, respectively. Moreover, the photocatalytic efficiency of the N–Fe–TNT hybrids improved as the Fe loading was increased gradually from 0.35% to 1.0%, though a further increase in Fe loadings led to reduced photocatalytic efficiency. The mineralization efficiencies of α-pinene and toluene were 43.2% and 47.7%, respectively. Gaseous intermediates were determined during the photocatalytic processes. Overall, the synthesized N–Fe–TNTs could be used efficiently to decompose α-pinene and toluene under visible-light exposure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N–Fe–TNTs were prepared via a combined sonochemical-hydrothermal-impregnation process. </LI> <LI> N–Fe–TNT hybrids showed improved efficiency compared to pure TNT and N-TNT. </LI> <LI> Mineralization efficiency and intermediates for photocatalysis were determined. </LI> <LI> N–Fe–TNT with a Fe loading of 1.0% showed the maximum photocatalytic efficiency. </LI> <LI> N–Fe–TNTs could be used capably to control pollutants with an efficiency up to 95%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Lee, Sung Won,Park, Joon Beom,Kim, Hwa Jin,Kim, Hye Young,Lee, Sang Yeob,Chung, Won Tae,Shin, Yoon Kyung,Park, Hwan Tae,Rho, Jee Hyun,Yoo, Young Hyun Elsevier 2018 Biochemical and biophysical research communication Vol.503 No.3
<P><B>Abstract</B></P> <P>Free fatty acids (FFAs) are considered the principal inducers of lipotoxicity, leading to cell dysfunction and/or cell death. Lipotoxicity in Schwann cells (SCs) damages neurons, which may be associated with peripheral neuropathies and axon degeneration. However, the molecular mechanism by which FFAs exert lipotoxicity in SCs remains to be established. In the present study, we demonstrate that palmitate exerts lipotoxicity in SCs through apoptosis and that palmitate-induced lipotoxicity in SCs is mediated through reactive oxygen species (ROS) generation. We observed that the six-transmembrane protein of prostate 2 (STAMP2), which plays a pivotal role in lipid homeostasis, is expressed in SCs. We further demonstrate that palmitate induces lipoapoptosis in SCs through ROS generation-mediated STAMP2 downregulation and that STAMP2 depletion accelerates the palmitate-exerted lipoapoptosis in SCs, indicating that STAMP2 confers on SCs the ability to resist palmitate-induced lipotoxicity. In conclusion, palmitate induces lipoapoptosis in SCs through ROS generation-mediated STAMP2 downregulation. Our findings indicate that ROS and STAMP2 may represent suitable targets for pharmacological interventions targeting lipotoxicity-associated peripheral neuropathies and axon degeneration.</P>
Lee, Jandee,Seol, Mi-Youn,Jeong, Seonhyang,Lee, Cho Rok,Ku, Cheol Ryong,Kang, Sang-Wook,Jeong, Jong Ju,Shin, Dong Yeob,Nam, Kee-Hyun,Lee, Eun Jig,Chung, Woong Youn,Jo, Young Suk Wolters Kluwer Health 2015 Medicine Vol.94 No.2
<▼1><P>Supplemental Digital Content is available in the text</P></▼1><▼2><P><B>Abstract</B></P><P>Metabolic reprogramming has been regarded as an essential component of malignant transformation. However, the clinical significance of metabolic heterogeneity remains poorly characterized.</P><P>The aim of this study was to characterize metabolic heterogeneity in thyroid cancers via the analysis of the expression of mitochondrial ribosomal proteins (MRPs) and genes involved in oxidative phosphorylation (OxPhos), and investigate potential prognostic correlations.</P><P>Gene set enrichment analysis (GSEA) verified by reverse transcription polymerase chain reaction and gene network analysis was performed using public repository data. Cross-sectional observational study was conducted to classify papillary thyroid cancer (PTC) by the expression of MRP L44 (MRPL44) messenger RNA (mRNA), and to investigate the clinicopathological features.</P><P>GSEA clearly showed that the expression of OxPhos and MRP gene sets was significantly lower in primary thyroid cancer than in matched normal thyroid tissue. However, 8 of 49 primary thyroid tumors (16.3%) in the public repository did not show a reduction in OxPhos mRNA expression. Remarkably, strong positive correlations between MRPL44 expression and those of OxPhos and MRPs such as reduced nicotinamide adenine dinucleotide dehydrogenase (ubiquinone) 1 α subcomplex, 5; succinate dehydrogenase complex, subunit D; cytochrome c, somatic; adenosine triphosphate synthase, H+ transporting, mitochondrial Fo complex, subunit C1 (subunit 9); and MRP S5 (MRPS5) (<I>P</I> < 0.0001) were clearly denoted, suggesting that MRPL44 is a representative marker of OxPhos and MRP expressions. In laboratory experiments, metabolic heterogeneity in oxygen consumption, extracellular acidification rates (ECARs), and amounts of OxPhos complexes were consistently observed in BCPAP, TPC1, HTH-7, and XTC.UC1 cell lines. In PTCs, metabolic phenotype according to OxPhos amount defined by expression of MRPL44 mRNA was significantly related to lymph node metastasis (LNM) (<I>P</I> < 0.001). Furthermore, multivariate analysis clearly indicated that expression of MRPL44 is associated with an increased risk of lateral neck LNM (odds ratio 9.267, 95% confidence interval 1.852–46.371, <I>P</I> = 0.007).</P><P>MRPL44 expression may be a representative marker of metabolic phenotype according to OxPhos amount and a useful predictor of LNM.</P></▼2>