• Title/Summary/Keyword: Removal mechanism

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Cold Ethanol Fractionation and Heat Inactivation of Hepatitis A Virus During Manufacture of Albumin from Human Plasma

  • Kim, In-Seop;Park, Yong-Woon;Lee, Sung-Rae;Sung, Hark-Mo
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.9 no.1
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    • pp.65-68
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    • 2004
  • The purpose of the present study was to examine the efficacy and mechanism of fraction IV cold ethanol fractionation and pasteurization (60$^{\circ}C$ heat treatment for 10 h), involved in the manufacture of albumin from human plasma, in the removal and/or inactivation of the hepatitis A virus (HAV). Samples from the relevant stages of the production process were spiked with HAV and the amount of virus in each fraction then quantified using a 50% tissue culture infectious dose (TCID$\_$50/). HAV was effectively partitioned from albumin during the fraction IV cold ethanol fractionation with a log reduction factor of 3.43. Pasteurization was also found to be a robust and effective step in inactivating HAV, where the titers were reduced from an initial titer of 7.60 log TCID$\_$50/ to undetectable levels within 5 h of treatment. The log reduction factor achieved during pasteurization was $\geq$4.76. Therefore, the current results indicate that the production process for albumin has sufficient HAV reducing capacity to achieve a high margin of virus safety.

A Preliminary Study on Polishing Process using Magnetorheological Fluid (자기유변유체를 활용한 연마공정에 대한 기초연구)

  • Hwang B.H.;Min B.K.;Lee S.J.;Seok J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.464-467
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    • 2005
  • Among several polishing techniques for micro structures, polishing process using magnetorheological(MR) fluid has advantages in the finishing process of 3-D micro structures because abrasives in the fluid can reach surfaces with complex feature and play their role. Although many researchers have been trying to reveal its polishing mechanism of the MR polishing, it has not been successful because in-situ measurement of state variables is difficult and process parameters are complex. In fact, one of the key factors for applying process control methodologies, such as Run-to-Run control, is the measuring and monitoring of slurry quality because the process strongly depends on the fluid property. Therefore, it is necessary to maintain consistent slurry quality to guarantee the process repeatability. The proposed equipment achieves the longer life cycle of MR fluid and reduces the variability of products. A new method to measure the material removal rate in MRF polishing process is also proposed and discussed.

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Modeling As(III) and As(V) adsorption and transport from water by a sand coated with iron-oxide colloids

  • Ko, Il-Won;Lee, Cheol-Hyo;Kim, Kyoung-Woong
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.04a
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    • pp.243-247
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    • 2004
  • Tile development of a porous iron-oxide coated sand filter system can be modelled with the analytical solution of tile transport equation in order to obtain the operating parameters and investigate the mechanism of arsenic removal. The adsorbed amount from the model simulation showed the limitation of adsorption removal during arsenic transport. A loss reaction term in the transport equation plays a role in the mass loss in column conditions, and then resulted into the better model fitting, particularly, for arsenate. Further, the competitive oxyanions delayed the breakthrough near MCL (10 $\mu$g/L) due to the competitive adsorption. This is the reason why arsenate can be strongly attracted in tile interface of an iron-oxide coated sand, and competing oxyanions can occupy the adsorption sites. Therefore, arsenic retention was regulated by non-equilibrium of arsenic adsorption in a porous iron-oxide coated sand media. The transport-limited process seemed to be affect the arsenic adsorption by coated sand.

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Utilization of Cotton Stalks-Biomass Waste in the Production of Carbon Adsorbents by KOH Activation for Removal of Dye-Contaminated Water

  • Fathy, Nady A.;Girgis, Badie S.;Khalil, Lila B.;Farah, Joseph Y.
    • Carbon letters
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    • v.11 no.3
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    • pp.224-234
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    • 2010
  • Four activated carbons were produced by two-stage process as followings; semi-carbonization of indigenous biomass waste, i.e. cotton stalks, followed by chemical activation with KOH under various activation temperatures and chemical ratios of KOH to semi-carbonized cotton stalks (CCS). The surface area, total pore volume and average pore diameter were evaluated by $N_2$-adsorption at 77 K. The surface morphology and oxygen functional groups were determined by SEM and FTIR, respectively. Batch equilibrium and kinetic studies were carried out by using a basic dye, methylene blue as a probe molecule to evaluate the adsorption capacity and mechanism over the produced carbons. The obtained activated carbon (CCS-1K800) exhibited highly microporous structure with high surface area of 950 $m^2/g$, total pore volume of 0.423 $cm^3/g$ and average pore diameter of 17.8 ${\AA}$. The isotherm data fitted well to the Langmuir isotherm with monolayer adsorption capacity of 222 mg/g for CCS-1K800. The kinetic data obtained at different concentrations were analyzed using a pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The pseudo-second-order model fitted better for kinetic removal of MB dye. The results indicate that such laboratory carbons could be employed as low cost alternative to commercial carbons in wastewater treatment.

Removal of haloacetonitrile by adsorption on thiol-functionalized mesoporous composites based on natural rubber and hexagonal mesoporous silica

  • Krueyai, Yaowalak;Punyapalakul, Patiparn;Wongrueng, Aunnop
    • Environmental Engineering Research
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    • v.20 no.4
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    • pp.342-346
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    • 2015
  • Haloacetonitriles (HANs) are nitrogenous disinfection by-products (DBPs) that have been reported to have a higher toxicity than the other groups of DBPs. The adsorption process is mostly used to remove HANs in aqueous solutions. Functionalized composite materials tend to be effective adsorbents due to their hydrophobicity and specific adsorptive mechanism. In this study, the removal of dichloroacetonitrile (DCAN) from tap water by adsorption on thiol-functionalized mesoporous composites made from natural rubber (NR) and hexagonal mesoporous silica (HMS-SH) was investigated. Fourier-transform infrared spectroscopy (FTIR) results revealed that the thiol group of NR/HMS was covered with NR molecules. X-ray diffraction (XRD) analysis indicated an expansion of the hexagonal unit cell. Adsorption kinetic and isotherm models were used to determine the adsorption mechanisms and the experiments revealed that NR/HMS-SH had a higher DCAN adsorption capacity than powered activated carbon (PAC). NR/HMS-SH adsorption reached equilibrium after 12 hours and its adsorption kinetics fit well with a pseudo-second-order model. A linear model was found to fit well with the DCAN adsorption isotherm at a low concentration level.

Studies on Estimating Dry Deposition Velocities for Atmospheric Aerosol and Metal Elements in Korea (한국에서 분진 및 금속원소의 건식 침착속도 추정에 관한 연구)

  • 김성천;김동술
    • Journal of Korean Society for Atmospheric Environment
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    • v.12 no.1
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    • pp.101-112
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    • 1996
  • Dry and wet deposition is an impertant removal mechanism of the amobient aerosol in the atmospheric environment. Since the deposition flut provides adverse impacts on various encironmental media including aquatic and ecological system as well as human health, it is essential to quantitatively estimate the removal fluxes of many air pollutants. Thus, the purposes of this experimental study are to investigate seasonal deposition flux variations of the total dustfall and various inorganic elements in the local ambient air and then to finally estimate their dry deposition velocities. To perform the study, the total of 90 dustfall samples were collected from January, 1994 thru February, 1995 in 5 different cities of Korea including Seoul, Suwon, Daejon, Kwangju, and Kangrung. Each sample was analyzed by an AAS and an ICP to determine the quantities of the 11 inorganic elements, such as Zn, Cd, Cr, K, Na, Pb, Ca, Fe, Mn, Mi, and Cu. As results, deposition fluxes, soluble/insoluble fractions, and deposition velocities for each element were extensively investigated. The resulting dry deposition velocities of some elements in Suwon were estimated by ranges of 0.57 .sim. 0.87 cm/sec for Zn, 0.35 .sim. 0.45 cm/sec for Pb, 1.25 .sim. 3.52 cm/sec for Ca, 0.21 .sim. 0.48 cm/sec for Fe, 0.95 .sim. 9.31 cm/sec for Mn, and 2.08 cm/sec for Cu.

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A Study on Oxidizer Effects in Tungsten CMP (텅스텐 CMP에서 산화제 영향에 관한 연구)

  • Park, Boumyoung;Lee, Hyunseop;Park, Kiyhun;Jeong, Sukhoon;Seo, Heondeok;Jeong, Haedo;Kim, Hoyoun;Kim, Hyoungjae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.9
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    • pp.787-792
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    • 2005
  • Chemical mechanical polishing(CMP) has become the process of choice for modem semiconductor devices to achieve both local and global planarization. CMP is a complex process which depends on numerous variables such as macro, micro and nano-geometry of pad, relative velocity between pad and wafer stiffness and dampening characteristics of pad, slurry, pH, chemical components of slurry, abrasive concentration, abrasive size, abrasive shape, etc. Especially, an oxidizer of chemical components is very important remove a target material in metal CMP process. This paper introduces the effect of oxidizer such as $H_2O_2,\;Fe(NO_3)_3\;and\;KIO_3$ in slurry for tungsten which is used in via or/and plug. Finally the duplex reacting mechanism of $oxidizer(H_2O_2)$ through adding the $catalyst(Fe(NO_3)_3)$ could acquire the sufficient removal rate in tungsten CMP.

Micro-machining of Glasses using Chemical-assisted Ultrasonic Machining (화학적 초음파가공을 이용한 유리의 미세가공)

  • 전성건;신용주;김병희;김헌영;전병희
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.12
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    • pp.2085-2091
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    • 2003
  • An ultrasonic machining process has been known as efficient and economical means fer precision machining of glass or ceramic materials. However, because of its complexity, the mechanism of the machining process is still not well understood. Therefore, it is hard to optimize the process parameters effectively. The conventional ultrasonic machining which uses the abrasive slurry only, furthermore, is time-consuming and gives the relatively rough surface. In order to increase the material removal rate and improve the integrity of the machined surface, we have introduced the novel ultrasonic machining technique, Chemical-assisted UltraSonic Machining(CUSM). The desktop-style micro ultrasonic machine has been developed and the z-axis feed is controlled by the constant load control algorithm. To obtain the chemical effects, the low concentration HF(hydrofluoric acid) solution, which erodes glass, added to alumina slurry. Through various experiments and comparison with conventional results, the superiority of CUSM is verified. MRR increases over 200%, the surface roughness is improved and the machining load decreases dramatically.

Variable Polarity Arc Welding of Aluminum Thin Plate (가변 극성을 이용한 박판 알루미늄 아크 용접)

  • Cho, Jungho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.2
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    • pp.89-93
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    • 2014
  • Variable polarity (VP) arc welding is known as an effective solution for aluminum thanks to the cleaning effect, which means oxide removal, during the DCEP (direct current electrode positive) period. In this research, VP GTAW (gas tungsten arc welding) is adopted for lap joint fillet welding of 3mm thickness 5052 aluminum alloy. Various welding currents and DCEP duty cycles are applied as welding conditions with a fixed welding speed to investigate the influence of DCEP characteristics on weld bead formation. Results show a tendency of higher heat input for higher DCEP duty cycle, which result does not follow conventional arc theory because it is known that DCEN (DC electrode negative) polarity is more efficient for heat input than is DCEP. This phenomenonhas recently been reported by several VP-GTA researchers and is still controversial because the mechanism of oxide removal is not yet clear except for the previous, well-known idea of "ion bombardment", which cannot explain the situation. Finally, proper usage conditions for VP-GTAW are suggested; then, further, related theoretical topics in the field of cathode physics are brieflyintroduced.

Electrochemical Oxidation of Phenol using Persulfate and Nanosized Zero-valent Iron (과황산염과 나노영가철을 이용한 페놀의 전기화학적 산화)

  • Kim, Cheolyong;Ahn, Jun-Young;Kim, Tae Yoo;Hwang, Inseong
    • Journal of Soil and Groundwater Environment
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    • v.22 no.2
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    • pp.17-25
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    • 2017
  • The efficiency and mechanism of electrochemical phenol oxidation using persulfate (PS) and nanosized zero-valent iron (NZVI) were investigated. The pseudo-first-order rate constant for phenol removal by the electrochemical/PS/NZVI ($1mA^*cm^{-2}/12$ mM/6 mM) process was $0.81h^{-1}$, which was higher than those of the electrochemical/PS and PS/NZVI processes. The electrochemical/PS/NZVI system removed 1.5 mM phenol while consuming 6.6 mM PS, giving the highest stoichiometric efficiency (0.23) among the tested systems. The enhanced phenol removal rates and efficiencies observed for the electrochemical/PS/NZVI process were attributed to the interactions involving the three components, in which the electric current stimulated PS activation, NZVI depassivation, phenol oxidation, and PS regeneration by anodic or cathodic reactions. The electrochemical/PS/NZVI process effectively removed phenol oxidation products such as hydroquinone and 1,4-benzoquinone. Since the electric current enhances the reactivities of PS and NZVI, process performance can be optimized by effectively manipulating the current.