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Fabrication and characterization of the nanofluids by the electrical explosion of the wire in liquid method

Department of Materials Science EngineeringAlthough nanofluids have superior and unique properties, the problem of dispersion stability and the mass production of nanofluids are still limited in the industrial applications. For this study, nanofluids were prepared using the electrical explosion of wire in liquids (EEWL) method. EEWL enables the manufacture of high-purity nanoparticles without the chemical additives. Other advantages of this method are its simple evaporation and condensation processes, short production times, and the feasibility for mass production. The EEWL method has been employed in the production of pure metallic nanofluids as well as their oxides. In this study, silver, copper oxide and aluminum oxide nanofluids were synthesized under various experimental parameters, such as voltage, capacitance, length of the wire and basefluid. The size of nanoparticles depends on the deposited energy value in the wire. The phase and morphology of nanoparticles are influenced by the basefluid and the additives. The nanoparticles synthesized by the EEWL process are spherical in shape. Copper oxide and aluminum oxide nanoparticles are synthesized in the water due to a chemical reaction with oxygen and hydroxyl. In the case of copper, the copper oxide nanoparticles were synthesized to be spherical in shape in the water as basefluid, whereas the 3D copper oxide structure particles were synthesized by adding sodium hydroxide (NaOH) or ammonia (NH3∙H2O) in the water. In this study, the metallic and oxide nanofluids were prepared in the various base fluids. The structure and morphology were investigated using various analysis tools, such as X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and field emission scanning electron microscopy. The optical band gap was determined using ultraviolet/visible spectroscopy. The impact of deposited energy in the wire on the size and shape of the nanoparticles were analyzed by using TEM analysis. In order to determine the optimized experimental conditions of nanofluids production, the investigation of the effects of experimental parameters are very important. As a method for the optimization of the process conditions, we used design of experiments (DOE) and analysis of calculated deposited energy values in the wire by measuring the voltage and current oscillograms. Through production of the silver nanofluids, optimized conditions can be determined by the MINITAB tool. The energy used in the explosion has to be experimentally quantified using the voltage and current oscillograms because it is difficult to directly measure the energy and to theoretically calculate it. Furthermore, the explosion phenomena can be explained by the analysis of the voltage and current oscillograms. The thermal conductivity and the viscosity of aluminum oxide nanofluids were measured and compared with the prediction models. The experimental results are similar to the prediction model, the increasing of the thermal conductivity and the viscosity could not be confirmed because of the very small concentration of nanoparticles. A pool boiling experiment was performed to investigate the effect of nanofluids on critical heat flux (CHF) enhancement. The nanofluids for experiments were prepared into two groups; 1) the water-based silver, copper oxide and aluminum oxide nanofluids synthesized by electrical explosion of the wire in liquid method and 2) xGnPs and xGnPs oxide nanofluids prepared by sonication. The silver, copper oxide and aluminum oxide nanofluids prepared by the electrical explosion of the wire in liquid process caused significant CHF enhancement during pool boiling experiments: 187% at 0.001 vol% for aluminum oxide, 58% at 0.001 vol% for silver, and 99% at 0.001 vol% for copper oxide nanofluids. The xGnPs oxide nanofluids dispersed with 0.005 vol% particles showed the largest CHF enhancement (189%). Deposition of nanoparticles on the wire surface occurs during nucleate boiling, and it can change the surface properties. In this study, the CHF phenomenon was also predicted using Kandlikar’s CHF model. The CHF results of silver, copper oxide and aluminum oxide nanofluids are in accord with the trend of the theoretical results. However, in case of the xGnPs and xGnPs oxide nanofluids, the CHF is enhanced with increasing of the contact angle value while CHF by Kandlikar’s model is enhanced with decrease the contact angle.ope

Understanding Open-Set Recognition by Jacobian Norm of Representation

In contrast to conventional closed-set recognition, open-set recognition (OSR) assumes the presence of an unknown class, which is not seen to a model during training. One predominant approach in OSR is metric learning, where a model is trained to separate the inter-class representations of known class data. Numerous works in OSR reported that, even though the models are trained only with the known class data, the models become aware of the unknown, and learn to separate the unknown class representations from the known class representations. This paper analyzes this emergent phenomenon by observing the Jacobian norm of representation. We theoretically show that minimizing the intra-class distances within the known set reduces the Jacobian norm of known class representations while maximizing the inter-class distances within the known set increases the Jacobian norm of the unknown class. The closed-set metric learning thus separates the unknown from the known by forcing their Jacobian norm values to differ. We empirically validate our theoretical framework with ample pieces of evidence using standard OSR datasets. Moreover, under our theoretical framework, we explain how the standard deep learning techniques can be helpful for OSR and use the framework as a guiding principle to develop an effective OSR model

Susceptibility to Oxidative Stress is Greater in Korean Patients with Coronary Artery Disease than Healthy Subjects

There are some evidences that the increased oxidative stress and thus increased oxidizability of lipoproteins and DNA can contribute to the development of certain human diseases, such as cardiovascular disease. To confirm the association of DNA damage with cardiovascular disease, we investigated susceptibility of DNA to oxidation in lymphocytes and oxidative stress related parameters in blood of patients with coronary artery disease (CAD). Subjects were consisted of 42 patients (27 men, 15 women) with documented CAD and 49 apparently healthy subjects (33 men, 16 women) as controls. Cellular DNA damage induced by 100 µM H2O2 was measured using Comet assay and quantified by TL. There were no differences in age (61.4 ± 1.7 years vs 62.0 ± 2.2 years) between the two groups. All the findings were shown to be independent of either sex or smoking habit. The patients showed significantly higher TL (87.3 ± 1.6 µm) compared to the control (79.3 ± 1.7 µm, p<0.01). Plasma TRAP, vitamin C, γ-tocopherol, and α-carotene levels in patients group were lower than those of control groups, while erythrocytic catalase activity increased in patients group. In conclusion, we observed that reduced overall antioxidant status was closely connected to higher susceptibility of DNA damage in CAD patients

Protective activity from hydrophilic and lipophilic free radical generators of Wen-Pi-Tang and its crude drug extracts in LLC-PK_1 cells

We investigated Wen-Pi-Tang and its crude drug extracts to determine their protective effect from oxidative stress caused by the hydrophilic and lipophilic free radical generators, 2,2\u27-azobis (2-amidino-propane) dihydrochloride (AAPH) and 2,2\u27-azobis(2,4-dimethylvaleronitrile) (AMVN) in LLC-PK_1 renal tubular epithelial cells. In response to AAPH and AMVN treatment, cell viability decreased significantly and significantly enhanced thiobarbituric acid-reactive substances (TBARS) formation was observed. However, Wen-Pi-Tang and its crude drug extracts showed scavenging of peroxyl radicals, which were generated by AAPH and AMVN, resulting in greater cell viability and lower TBARS formation than controls treated only with free radical generators. In particular, Wen-Pi-Tang, Rhei Rhizoma and Ginseng Radix demonstrated high protective activity, whereas Aconiti Tuber, Zingiberis Rhizoma and Glycyrrhizae Radix showed relatively low activity. This result suggests that the antioxidant activity of Wen-Pi-Tang was attributable to the crude extracts, and that both act as hydrophilic and lipophilic antioxidants. 水溶性アゾ化合物のAAPH(2,2\u27-azobis(2-amidino-propane)dihydrochloride)と脂溶性アゾ化合物のAMVN(2,2\u27-azobis(2,4dimethylvaleronitrile))で腎上皮細胞のLLC-PK1に酸化的ストレスを惹起させ,温脾湯と5種類の構成和漢薬の効果を検討した。AAPHとAMVNで処埋した場合,細胞生有率が著しく抵ドし,チオバルビツール酸反応物質の生成が著しく上昇したが,温脾湯と各構成和漢薬エキスをそれぞれ添加した場合,温脾湯と大黄,薬用人参では高い抗酸化活性を示した。しかし附子,乾姜,甘草では相対的に低いi活牲であった。このことから,温脾湯の抗酸化活性は構成和漢薬に起因し,また温脾湯は水溶性抗酸化物と脂溶性抗酸化物の両方の特徴を有していることが示唆された

Anisotropic Thermal Conductivity of Nickel-Based Superalloy CM247LC Fabricated via Selective Laser Melting

Efforts to enhance thermal efficiency of turbines by increasing the turbine inlet temperature have been further accelerated by the introduction of 3D printing to turbine components as complex cooling geometry can be implemented using this technique. However, as opposed to the properties of materials fabricated by conventional methods, the properties of materials manufactured by 3D printing are not isotropic. In this study, we analyzed the anisotropic thermal conductivity of nickel-based superalloy CM247LC manufactured by selective laser melting (SLM). We found that as the density decreases, so does the thermal conductivity. In addition, the anisotropy in thermal conductivity is more pronounced at lower densities. It was confirmed that the samples manufactured with low energy density have the same electron thermal conductivity with respect to the orientation, but the lattice thermal conductivity was about 16.5% higher in the in-plane direction than in the cross-plane direction. This difference in anisotropic lattice thermal conductivity is proportional to the difference in square root of elastic modulus. We found that ellipsoidal pores contributed to a direction-dependent elastic modulus, resulting in anisotropy in thermal conductivity. The results of this study should be beneficial not only for designing next-generation gas turbines, but also for any system produced by 3D printing

Mutagenic activity of river water from a river near textile industrial complex in Korea

The mutagenic activity of XAD-2 adsorbates and water extracts recovered from nine locations of the Kumho River was tested on S. typhimurium TA98 strain to identify the source of the mutagenicity. A sampling site, receiving effluents from the textile industrial complex located in Daegu City, showed extraordinarily high mutagenic activity, especially in the presence of S9 mixture, at all sampling time in both XAD-2 adsorbates and dichloromethane extracts. This indicated the existence of the frame-shift mutagens in the Kumho River, same type of mutagens detected in previous studies by other researchers in the Nakdong River into which the Kumho River discharges. The fractionation study showed that the mutagenic chemicals in the river water are mid-polar. Furthermore, mean tail length obtained by single cell gel electrophoresis assay (Comet assay) showed consistent dose-dependent DNA damage, indicating that the chemicals in the river water not only act as frame-shift mutagens but also break human lymphocytes DNA strain. Chemical identification of the mutagens should be require

Glycemic status, insulin resistance, and mortality from lung cancer among individuals with and without diabetes

Background: The effects of glycemic status and insulin resistance on lung cancer remain unclear. We investigated the associations between both glycemic status and insulin resistance, and lung cancer mortality, in a young and middle-aged population with and without diabetes. Methods: This cohort study involved individuals who participated in routine health examinations. Lung cancer mortality was identified using national death records. Cox-proportional hazards models were used to calculate hazard ratios (HRs) with 95% CIs for lung cancer mortality risk. Results: Among 666,888 individuals (mean age 39.9±10.9 years) followed for 8.3 years (interquartile range, 4.6–12.7), 602 lung cancer deaths occurred. Among individuals without diabetes, the multivariable-adjusted HRs (95% CI) for lung cancer mortality comparing hemoglobin A1c categories (5.7–5.9, 6.0–6.4, and ≥ 6.5% or 36–38, 39–46, and ≥ 48 mmol/mol, respectively) with the reference (&lt; 5.7% or &lt; 36 mmol/mol) were 1.39 (1.13–1.71), 1.72 (1.33–2.20), and 2.22 (1.56–3.17), respectively. Lung cancer mortality was associated with fasting blood glucose categories in a dose-response manner (P for trend = 0.001) and with previously diagnosed diabetes. Insulin resistance (HOMA-IR ≥ 2.5) in individuals without diabetes was also associated with lung cancer mortality (multivariable-adjusted HR, 1.41; 95% CI, 1.13–1.75). These associations remained after adjusting for changing status in glucose, hemoglobin A1c, insulin resistance, smoking status, and other confounders during follow-up as time-varying covariates. Conclusions: Glycemic status within both diabetes and prediabetes ranges and insulin resistance were independently associated with an increased risk of lung cancer mortality. Keywords Diabetes mellitus, Glycated hemoglobin A1c, Hyperglycemia, Insulin resistance, Lung cancer<br/

Understanding NK cell biology for harnessing NK cell therapies: targeting cancer and beyond

Gene-engineered immune cell therapies have partially transformed cancer treatment, as exemplified by the use of chimeric antigen receptor (CAR)-T cells in certain hematologic malignancies. However, there are several limitations that need to be addressed to target more cancer types. Natural killer (NK) cells are a type of innate immune cells that represent a unique biology in cancer immune surveillance. In particular, NK cells obtained from heathy donors can serve as a source for genetically engineered immune cell therapies. Therefore, NK-based therapies, including NK cells, CAR-NK cells, and antibodies that induce antibody-dependent cellular cytotoxicity of NK cells, have emerged. With recent advances in genetic engineering and cell biology techniques, NK cell-based therapies have become promising approaches for a wide range of cancers, viral infections, and senescence. This review provides a brief overview of NK cell characteristics and summarizes diseases that could benefit from NK-based therapies. In addition, we discuss recent preclinical and clinical investigations on the use of adoptive NK cell transfer and agents that can modulate NK cell activity