• 제목/요약/키워드: controlled synthesis

검색결과 625건 처리시간 0.031초

귀비탕과 그 변방의 만성피로증후군 증상완화에 대한 효용성: 체계적인 문헌고찰 (Is Gwibitang and its modification beneficial for alleviating symptoms in chronic fatigue syndrome: A systematic review and meta-analysis)

  • 남동현
    • 대한한의학방제학회지
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    • 제28권2호
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    • pp.199-209
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    • 2020
  • Objectives : The purpose of this systematic review is to confirm whether Gwibitang is beneficial in chronic fatigue syndrome (CFS). Methods : Clinical trials were searched from databases including Pubmed, Embase, Central Cochrane, CNKI, Wanfang, CQVIP, CiNii, OASIS, Koreamed, and NDSL. The eligible study design was limited into randomized controlled trial, quasi-randomized controlled trial and controlled clinical trial. The outcomes included general effectiveness as nominal scale, and fatigue severity, insomnia severity and quality of life as interval or ratio scale. The meta-analysis and assessment of risk of bias was performed based on the data extracted from the selected trials. Results : The results of eight randomized controlled trials (n=596) were included in the meta-analysis. The results of the synthesis showed Gwibitang is beneficial substantially for relieving and managing the general symptoms, and its heterogeneity was not in important level (RR 0.26 [95% CI 0.17, 0.39], Z=6.47, P<0.00001, I2=0%). Gwibitang was beneficial for alleviating fatigue (SMD -0.78 [95% CI -1.27, -0.30], Z=3.17, P=0.002), but its certainty was low. In case of insomnia, too few trials had been found and their risk of bias was substantial, so no conclusions had been brought to. Conclusions : We found an evidence that Gwibitang could be beneficial for managing and alleviating main symptoms in CFS patients.

수소이온 전도성 가지형 공중합체 전해질막 제조 및 분석 (Synthesis and Characterization of Proton Conducting Graft Copolymer Membranes)

  • 노동규;고종관;서진아;김종학
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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    • pp.126.2-126.2
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    • 2010
  • The "grafting from" technology to prepare the well-defined microphase-separated structure of polymer using atom transfer radical polymerization (ATRP) will be introduced in this presentation. Various amphiphilic comb copolymers were synthesized through this approach using poly (vinylidene fluoride) (PVDF), poly (vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-co-CTFE) and poly(vinyl chloride) (PVC) as a macroinitiator. Hydrophilic side chains such as poly (styrene sulfonic acid) (PSSA) or poly (sulfopropyl methacrylate) (PSPMA) were grafted from the mains chains using direct initiation of the chlorine atoms. The structure of mass transport channels has been controlled and fixed by crosslinking the hydrophobic domains, which also provides the greater mechanical properties of membranes. Successful synthesis and microphase-separated structure of the polymer were confirmed by $^1H$ NMR, FT-IR spectroscopy and TEM. The grafted/crosslinked membranes exhibited good mechanical properties (400 MPa of Young's modulus) and high thermal stability (up to $300^{\circ}C$), as determined by a universal testing machine (UTM) and TGA, respectively.

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Plasma Engineering for Nano-Materials

  • Kim, Seong-In;Shin, Myoung-Sun;Son, Byung-Koo;Song, Seok-Kyun;Choi, Sun-Yong
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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    • pp.79-79
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    • 2012
  • A high temperature and a low temperature plasma process technologies were developed and demonstrated for synthesis, hybrid formation, surface treatment and CVD engineering of nano powder. RF thermal plasma is used for synthesis of spherical nano particles in a diameter ranged from 10 nm to 100 nm. A variety of nano particules such as Si, Ni, has been synthesized. The diameter of the nano-particles can be controlled by RF plasma power, pressure, gas flow rate and raw material feed rate. A modified RF thermal plasma also produces nano hybrid materials with graphene. Hemispherical nano-materials such as Ag, Ni, Si, SiO2, Al2O3, size ranged from 30 to 100 nm, has been grown on graphene nanoplatelet surface. The coverage ranged from 0.1 to 0.7 has been achieved uniformly over the graphene surface. Low temperature AC plasma is developed for surface modification of nano-powder. In order to have a three dimensional and lengthy plasma treatment, a spiral type of reactor has been developed. A similar plasma reactor has been modfied for nano plasma CVD process. The reactor can be heated with halogen lamp.

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Synthesis and characterization Au doped TiO2 film for photocatalytic function

  • Son, Jeong-Hun;Bae, Byung-Seo;Bae, Dong-Sik
    • 한국결정성장학회지
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    • 제25권6호
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    • pp.280-284
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    • 2015
  • Au doped $TiO_2$ nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. Au doped $TiO_2$ was coated with glass substrate. The size of the particles and thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of TTIP within the micro-emulsion. The average size of synthesized Au doped $TiO_2$ nanoparticle was about in the size range of 15 to 25 nm and the Au particles formed mainly the range of 2 to 10 nm in diameter. The effect of synthesis parameters, such as the molar ratio of water to TTIP and the molar ratio of water to surfactant, are discussed. The synthesized nanopaticles were coated on glass substrate by a spin coating process. The thickness of thin film was about 80 nm. The degradation of MB on a $TiO_2$ thin film was enhanced over 20 % efficiency by the incorporation of Au.

PVA 함유 수용액으로부터 초음파 조사에 의한 CdSe 중공 입자의 합성 (Synthesis of hollow Sphere CdSe in PVA Aqueous Solution by Using Ultrasonic Irradiation)

  • 박명국;이윤복;김용진;김인배;김양도
    • 한국세라믹학회지
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    • 제44권2호
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    • pp.84-88
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    • 2007
  • CdSe hollow spheres with the diameter of about 30-50 nm were synthesized after ultrasonic irradiation in the presence of $Cd(NO_3)_2,\;Na_2SeSO_3$, and polyvinylalcohol(PVA). The characteristics of CdSe hollow spheres were analyzed using X-ray diffraction(XRD), transmission electron microscopy(TEM), UV-vis measurement and PL spectrometer. The characteristics of solvent as water and water-1-propanol mixture in the system played important roles on the controlled synthesis of hollow sphere. Based on the observation of morphological difference of CdSe, the possible mechanism of CdSe hollow sphere formation will be discussed.

공압인공근육을 이용한 조작기 위치의 강인제어 (Robust Control of the Position of a Manipulator Using Pneumatic Artificial Muscle)

  • 박노철;양현석;박영필
    • 대한기계학회논문집A
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    • 제20권6호
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    • pp.1882-1892
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    • 1996
  • This paper is concerned with the position control of the ond degree-of freedom manipulator using pneumatic artificial muscle actuator which is built to have a proper compliance. For t his pneumatic artificial muscle actuator though, it is difficult to make an effective control scheme due to the nonlinearity and uncertainties on the dynamics of the actuator. In this paper, a third-order equation of motion is derived for the actuator including the dynamics of the pneumatic servovalve. Later, various modeling uncertainties due to the nonlinearity and unmodeled dynamics of the servo vlave and the actuator are taken care of, as a trade-off between the closed-loop performance of the controlled system and its robustness to uncertainties. A controller using .mu. synthesis thchnique is designed, and robust performance against measurement noise, various modeling uncertainties due to the dynamics of the servo valve and actuator is achieved. The effectiveness of the proposed control methods is illustrated through simulations and experiments.

수용성 아크릴 변성 에폭시에스테르 수지의 합성 및 도막물성 (Synthesis of Water Soluble Acrylic Modified Epoxyester Resin and Physical Properties of Coatings)

  • 김성길;신판우;이동찬
    • 한국응용과학기술학회지
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    • 제28권1호
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    • pp.35-47
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    • 2011
  • For the synthesis of water soluble acrylic modified epoxyester resin, fatty acid/epoxy ratio of 50/50 was used, and introduced maleic anhydride. Ratio of styrene/acrylic acid of acrylic monomers was fixed 85/15 and ratio of epoxyester/acrylic monomer was controlled 80/20, 75/25, 70/30, 65/35, and degree of neutralization were changed 65%, 80%, to 100%. As a result, 40% solids acrylic modified epoxyester resins were synthesized. Resins were evaluated water soluble stability, drying time, water resistant, storage stability and physical properties. And the white paints were prepared, and were evaluated viscosity, drying time, water resistance, adhesion, sagging, spray workability, gloss, salt spray resistance, skinning, whiteness and flash rust. As a result, the degree of neutralization of 100% and the ratio of epoxyester/acrylic monomer of 75/25 showed the best properties.

졸겔 연소법에 의한 nano crystalline ITO제작 및 특성 (Synthesis of nano porous indium tin oxide by sol-gel combustion hybrid method)

  • 정기영;곽동주;성열문;박차수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2009년도 제40회 하계학술대회
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    • pp.1328_1329
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    • 2009
  • Nano porous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of $SnCl_4$-98.0% and $In(NO_3)_3{\cdot}XH_2O$-99.999%, produce with a $NH_4OH$ with sol-gel method as a catalyst [1,2]. Crystal structures were examined by powder X-ray diffraction (XRD), and those results show shaper intensity peak at $25.6^{\circ}(2{\Theta})$ of $SnO_2$ by increased sintering temperature. A particle morphology as well as crystal size was investigated by scanning electron microscopy(FE-SEM), and the size of the nano porous powder was found to be in the range of 20~30nm. ITO films could controlled by nano porous powder at various sintering temperature in this paper[3,4]. The sol-gel combustion method was offered simple and effective route for the synthesis of nano porous ITO powder[5].

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혈청 콜레스테롤과 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase (Serum Cholesterol and 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase)

  • 최용순;이상영
    • 한국식품영양과학회지
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    • 제21권5호
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    • pp.580-593
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    • 1992
  • Cholesterol have many essential functions as a component of cellular and subcellular membranes, metabolic precursor of bile acids and steroid hormones, and obligatory part of the metabolic systems involved in DNA synthesis and cell division. These essential funtions demand a continuous and appropriate supply of cholesterol to the tissues. Body cholesterol pool is maintained by the balance of acquirement from diets, de novo synthesis, and excretion either as bile acids or neutral steroids. In these metabolic process, cholesterol biosynthesis is controlled by the change in the activity of 3-hydroxy-3methylglutaryl coenzyme A (HMG-CoA) reductase. Under most physiological or nutritional situations, the activity of this enzyme is adroitly regulated to maintain tissue cholesterol balance. Excess cholesterol accumulation in the cells induces the decrease in the number of LDL-receptor, followed by the increase in the level of serum LDL-cholesterol. Increase in the level of serum cholesterol appears to be an important determinant for the incidence of the coronary heart disease. Dietary intervention may be helpful in alleviating an increase in the level of serum cholesterol or body cholesterol pool.

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TiOCl2 수용액의 균일침전반응에 의한 나노크기의 브루카이트상 TiO2 분말제조 (Synthesis of Nanosized Brookite-type Titanium Dioxide Powder from aqueous TiOCl2 Solution by homogeneous Precipitation Reaction)

  • 이정훈;양영석
    • 한국재료학회지
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    • 제12권12호
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    • pp.947-954
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    • 2002
  • HCl concentration and reaction time are the decisive factors in determining the structure of precipitates in the process of synthesis of $TiO_2$ particles from aqueous $TiOCl_2$ solution by precipitation and the volumetric proportion of brookite phase in $TiO_2$ particles can be controlled by these two factors. As reaction rate increases with increase of reaction temperature, the reaction time, at which maximum volumetric proportion of brookite phase in $TiO_2$ particles was obtained, was reduced. The brookite was transformed directly to rutile phase with only increase of reaction time. And precipitation was delayed with increase of HCl concentration because the amount of $H_2$O, which is necessary source of oxygen for conversion of $Ti^{+4}$ to $TiO_2$, was relatively reduced with increase of that. Brookite in the mixture phase powder was finally transformed to rutile phase via anatase through heat-treatment.