• 상하수도학회지
• /
• 제35권6호
• /
• pp.425-436
• /
• 2021

In this study, chemically enhanced steam cleaning(CESC) was applied as a novel and efficient method for the control of organic and inorganic fouling in ceramic membrane filtration. The constant filtration regression model and the resistance in series model(RISM) were used to investigate the membrane fouling mechanisms. For total filtration, the coefficient of determination(R²) with an approximate value of 1 was obtained in the intermediate blocking model which is considered as the dominant contamination mechanism. In addition, most of the coefficient values showed similar values and this means that the complex fouling was formed during the filtration period. In the RISM, R _c/R _f increased about 4.37 times in chemically enhanced steam cleaning compared to physical backwashing, which implies that the internal fouling resistance was converted to cake layer resistance, so that the membrane fouling hardly to be removed by physical backwashing could be efficiently removed by chemically enhanced steam cleaning. The results of flux recovery rate showed that high-temperature steam may loosen the structure of the membrane cake layer due to the increase in diffusivity and solubility of chemicals and finally enhance the cleaning effect. As a consequence, it is expected that chemically enhanced steam cleaning can drastically improve the efficiency of membrane filtration process when the characteristics of the foulant are identified.

• 한국재료학회지
• /
• 제33권5호
• /
• pp.214-221
• /
• 2023

As a filler metal for lowering the melting point of Ag, many alloy metal candidates have emerged, such as cadmium, with zinc, manganese, nickel, and titanium as active metals. However, since cadmium is known to be harmful to the human body, Cd-free filler metals are now mainly used. Still, no study has been conducted comparing the characteristics of joints prepared with and without cadmium. In addition, studies have yet to be conducted comparing the typical characteristics of brazing filler metals with special structures, and the joint characteristics of brazing filler metals with available frames. In this study, the characteristics of junctions of silver-based intercalation metals were compared based on the type of filler metal additives, using a special structure, a filler metal sandwich structure, to protect the internal base metal. The general filler metal was compared using the structure, and the thickness of the filler metal according to the thickness was reached. A comparison of the characteristics of the junction was conducted to identify the characteristics of an intersection of silver-based brazing filler metal and the effect on joint strength. Each filler metal's collective tensile strength was measured, and the relationship between joint characteristics and tensile joint strength was explored. The junction was estimated through micro strength measurement, contact angle measurement with the base metal when the filler metal was melted, XRD image observation, composition analysis for each phase through SEM-EDS, and microstructure phase acquisition.

• Animal Bioscience
• /
• 제36권10호
• /
• pp.1568-1577
• /
• 2023

Objective: A study was conducted to determine the chemical composition of banana meal and rice bran from Australia or South-East Asia and test the hypothesis that there are no differences in rice bran produced in different countries, but there are differences between full-fat and defatted rice bran. Methods: Two sources of banana meal and 22 sources of rice bran (full-fat or defatted) from Australia or South-East Asia were used. All samples were analyzed for dry matter, gross energy, nitrogen, amino acids (AA), acid hydrolyzed ether extract (AEE), ash, minerals, total starch, insoluble dietary fiber, and soluble dietary fiber. Banana meal was also analyzed for sugars including glucose, fructose, maltose, sucrose, stachyose, and raffinose. Results: Chemical analysis demonstrated that banana meal from the Philippines is primarily composed of starch. Full-fat rice bran from Australia had greater (p<0.05) concentrations of AEE, lysine, and glycine than samples from the Philippines and Vietnam. Full-fat rice bran from Australia and Thailand had greater (p<0.05) concentrations of gross energy and most AA than rice bran from Vietnam. Full-fat rice bran from Australia had greater (p<0.05) concentrations of tryptophan and manganese than all other sources, but full-fat rice bran from the Philippines contained less (p<0.05) zinc than all other sources of rice bran. Gross energy, AEE, and copper were greater (p<0.05) in full-fat rice bran compared with defatted rice bran, but defatted rice bran contained more (p<0.05) crude protein, ash, insoluble dietary fiber, total dietary fiber, AA, and some minerals than full-fat rice bran. Conclusion: Banana meal is a high-energy source that can be used as an alternative ingredient in livestock diets. Full-fat rice bran from Australia and Thailand contained more concentrations of AEE and AA than samples from the Philippines or Vietnam. Full-fat rice bran had more gross energy and AEE than defatted rice bran, whereas defatted rice bran contained more crude protein, ash, and total dietary fiber.

• Journal of Yeungnam Medical Science
• /
• 제40권2호
• /
• pp.136-145
• /
• 2023

Hepatic encephalopathy (HE) is a severe neuropsychiatric abnormality in patients with either acute or chronic liver failure. Typical brain magnetic resonance imaging findings of HE are bilateral basal ganglia high signal intensities due to manganese deposition in chronic liver disease and hyperintensity in T2, fluid-attenuated inversion recovery, or diffusion-weighted imaging (DWI) with hemispheric white matter changes including the corticospinal tract. Low values on apparent diffusion coefficient mapping of the affected area on DWI, indicating cytotoxic edema, can be observed in acute HE. However, neuropsychological impairment in HE ranges from mild deficits in psychomotor abilities affecting quality of life to stupor or coma with higher grades of hepatic dysfunction. In particular, the long-lasting compensatory mechanisms for the altered metabolism in chronic liver disease make HE imaging results variable. Therefore, the clinical relevance of imaging findings is uncertain and differentiating HE from other metabolic diseases can be difficult. The recent introduction of concepts such as "acute-on-chronic liver failure (ACLF)," a new clinical entity, has led to a change in the clinical view of HE. Accordingly, there is a need to establish a corresponding concept in the field of neuroimaging diagnosis. Herein, we review HE from a historical and etiological perspective to increase understanding of brain imaging and help establish an imaging approach for advanced new concepts such as ACLF. The purpose of this manuscript is to provide an understanding of HE by reviewing neuroimaging findings based on pathological and clinical concepts of HE, thereby assisting in neuroimaging interpretation.

• International Journal of Computer Science & Network Security
• /
• 제24권6호
• /
• pp.200-206
• /
• 2024

Laser induced breakdown spectroscopy (LIBS) technique has been used for the elemental composition of the soils. In this technique, a high energy laser pulse is focused on a sample to produce plasma. From the spectroscopic analysis of such plasma plume, we have determined the different elements present in the soil. This technique is effective and rapid for the qualitative and quantitative analysis of all type of samples. In this work a Q-switched Nd: YAG laser operating with its fundamental mode (1064 nm laser wavelength), 5 nanosecond pulse width, and 10 Hz repetition rate was focused on soil samples using 10 cm quartz lens. The emission spectra of soil consist of Iron (Fe), Calcium (Ca), Titanium (Ti), Silicon (Si), Aluminum (Al), Magnesium (Mg), Manganese (Mn), Potassium (K), Nickel (Ni), Chromium (Cr), Copper (Cu), Mercury (Hg), Barium (Ba), Vanadium (V), Lead (Pb), Nitrogen (N), Scandium (Sc), Hydrogen (H), Strontium (Sr), and Lithium (Li) with different finger-prints of the transition lines. The maximum intensity of the transition lines was observed close to the surface of the sample and it was decreased along the axial direction of the plasma expansion due to the thermalization and the recombination process. We have also determined the plasma parameters such as electron temperature and the electron number density of the plasma using Boltzmann's plot method as well as the Stark broadening of the transition lines respectively. The electron temperature is estimated at 14611 °K, whereas the electron number density i.e. 4.1 × 10¹⁶ cm^-3 lies close to the surface.

• Biomolecules & Therapeutics
• /
• 제32권1호
• /
• pp.77-83
• /
• 2024

Alzheimer's disease (AD) is a neurodegenerative disease characterized by neuronal cell death and memory impairment. Corticosterone (CORT) is a glucocorticoid hormone produced by the hypothalamic-pituitary-adrenal axis in response to a stressful condition. Excessive stress and high CORT levels are known to cause neurotoxicity and aggravate various diseases, whereas mild stress and low CORT levels exert beneficial actions under pathophysiological conditions. However, the effects of mild stress on AD have not been clearly elucidated yet. In this study, the effects of low (3 and 30 nM) CORT concentration on Aβ_25-35-induced neurotoxicity in SH-SY5Y cells and underlying molecular mechanisms have been investigated. Cytotoxicity caused by Aβ_25-35 was significantly inhibited by the low concentration of CORT treatment in the cells. Furthermore, CORT pretreatment significantly reduced Aβ_25-35-mediated pro-apoptotic signals, such as increased Bim/Bcl-2 ratio and caspase-3 cleavage. Moreover, low concentration of CORT treatment inhibited the Aβ_25-35-induced cyclooxygenase-2 and pro-inflammatory cytokine expressions, including tumor necrosis factor-α and interleukin-1β. Aβ_25-35 resulted in intracellular accumulation of reactive oxygen species and lipid peroxidation, which were effectively reduced by the low CORT concentration. As a molecular mechanism, low CORT concentration activated the nuclear factor-erythroid 2-related factor 2, a redox-sensitive transcription factor mediating cellular defense and upregulating the expression of antioxidant enzymes, such as NAD(P)H:quinone oxidoreductase, glutamylcysteine synthetase, and manganese superoxide dismutase. These findings suggest that low CORT concentration exerts protective actions against Aβ_25-35-induced neurotoxicity and might be used to treat and/or prevent AD.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2016년도 추계학술대회 논문집
• /
• pp.197-197
• /
• 2016

Commercially pure titanium (CP Ti) and Ti-6Al-4V alloys have been widely used for biomedical applications. However, the use of the Ti-6Al-4V alloy in biomaterial is then a subject of controversy because aluminum ions and vanadium oxide have potential detrimental influence on the human body due to vanadium and aluminum. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Manganese(Mn) plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. Radio frequency(RF) magnetron sputtering in the various PVD methods has high deposition rates, high-purity films, extremely high adhesion of films, and excellent uniform layers for depositing a wide range of materials, including metals, alloys and ceramics like a hydroxyapatite. The aim of this study is to research the Mn coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. Mn coatings was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Mn coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• 전기화학회지
• /
• 제12권1호
• /
• pp.81-87
• /
• 2009

리튬 이차전지의 양극 활물질인 스피넬 망간산화물(${LiMn_2}{O_4}$, LMO) 표면에 ITO(indium tin oxide)를 코팅하여, 고온($55^{\circ}C$)에서 사이클 수명과 속도특성을 조사하였다. 정전류 정전압 충방전 실험의 결과, ITO가 코팅되지 않은 LMO 전극의 표면에서 고온 고전압 조건에서 전해질이 분해하여 피막이 형성되고, 이 피막의 저항으로 인하여 분극현상(polarization)이 심하게 발생하였다. 그러나, ITO가 2 mol% 이상 코팅된 LMO의 경우 양극 활물질과 전해질과의 직접적인 접촉 면적이 줄어들어, 전해질의 분해가 감소하였고 내부저항에 의한 분극 현상 또한 현저히 감소하였다. 이러한 결과, ITO가 코팅된 전극의 충방전에 따른 가역성이 코팅되지 않은 LMO에 비해 크게 향상되었다. 적외선 분광기를 이용하여 ITO가 코팅된 LMO 표면에서 피막형성이 감소함을 확인하였다. ITO의 코팅으로 LMO 전극의 속도특성도 크게 향상되었는데, 이는 저항이 큰 피막형성이 억제된다는 점과 ITO의 전기전도도가 크다는 사실로 설명할 수 있다.

• 농업생명과학연구
• /
• 제45권6호
• /
• pp.251-263
• /
• 2011

본 연구에서는 폐금속 광산 주변 비소와 중금속으로 오염된 논토양을 효과적으로 복원하기 위한 안정화제로써 석회석과 제강슬래그의 처리효과와 그 적용성을 검토하기 위해 담수답의 환원 환경을 적용한 컬럼 실험을 실시하였다. 실험결과 담수된 논토양의 환원 환경에서는 철과 망간 성분이 환원되어 급격하게 용출되는 시점에 중금속 성분도 급격하게 용출되는 경향이 나타났으며, 대조구(무처리)의 경우 침출수에서 오염기준을 초과한 시료가 나타났다. 그러나 석회석 5%와 제강슬래그 5%로 각각 처리한 토양은 모두 오염기준 이하로 대조구보다 중금속 농도가 매우 낮게 검출되었다. 석회석과 제강슬래그 모두 담수답의 환원 환경에서 좋은 처리효과를 나타내어 효과적인 안정화제로 판단되었으며, 특히 제강슬래그는 담수답 환경에서 지속적으로 증가하는 비소 성분에 대해서 좋은 처리효과를 나타내었다.

• 자원리싸이클링
• /
• 제32권1호
• /
• pp.21-32
• /
• 2023

리튬이온 배터리(LIB) 제조를 위한 리튬의 사용이 점차 증가함에 따라 그에 따라 발생되는 리튬이온배터리 폐기가 증가될 것으로 사료된다. 이에 따라 폐배터리를 재활용을 하기위한 용매 추출을 통한 재활용에 대한 활발한 연구가 니켈, 코발트 및 망간과 같은 유가금속을 제거한 후 얻은 폐 용액에서 리튬의 회수가 중요하다. 본 연구에서는 폐이차전지 재활용공정 후 발생되는 폐액에서 리튬을 회수하기위해 추출제 Di-(2-ethylhexyl) hosphoricacid(D2EHPA)와 등유의 개질제 Tri-n-butyphosphate(TBP)를 선택적으로 혼합하여 추출조건을 최적화하였다. 폐액에는 리튬과 고농도의 나트륨(Li⁺ = 0.5% ~ 1%, Na⁺ = 3 ~ 6.5%)을 함유하고 있었으며, 리튬의 추출은 유기용매의 다른 구성에서 최종적으로 20% D2EHPA + 20% TBP + 60% 등유로 구성된 유기용매에서 효과적인 추출을 조건을 확립하였다. NaOH의 비누화를 이용한 SX 시스템에서는 평형 pH 4~4.5에서 유기 대 수성(O/A)이 5일 때 약 95% 이상의 리튬이 선택적으로 추출되는 것을 확인하였다. 적은 양의 나트륨으로 염화리튬에서 탄산리튬 분말을 얻기 위해 고순도 중탄산암모늄을 처리하였다. 최종적으로 처리된 탄산리튬에 여러번 세수를 통하여 미량의 나트륨을 제거하고 고순도 탄산리튬 분말(순도 99.2%)을 제조하였다. 따라서 본 연구를 통하여 폐이차전지 재활용공정에서 발생되는 폐액을 활용하여 탄산리튬의 효율적인 제조방법을 확인하였다.