• Title/Summary/Keyword: controlled synthesis

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Synthesis and Electrochemical Studies of Cu(II) and Ni(II) Complexes with Tetradentate Schiff Base Ligands

  • 조기형;정병구;김정희;전승원;임채평;최용국
    • Bulletin of the Korean Chemical Society
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    • v.18 no.8
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    • pp.850-856
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    • 1997
  • A series of tetradentate Schiff-base ligands; 1,3-bis(salicylideneimino) propane, 1,4-bis(salicylideneimino)butane, and 1,5-bis(salicylideneimino)pentane, and their Cu(Ⅱ) and Ni(Ⅱ) complexes have been synthesized. The properties of ligands and complexes have been characterized by elemental analysis, IR, NMR, UV-Vis spectra, molar conductance, and thermogravimetric anaylsis. The mole ratio of Schiff base to metal at complexes was found to be 1 : 1. All complexes were four-coordinated configuration and non-ionic compound. The electrochemical redox processes of the ligands and their complexes in DMF solution containing 0.1 M TEAP as supporting electrolyte have been investigated by cyclic voltammetry, chronoamperometry, differential pulse voltammetry at glassy carbon electrode, and by controlled potential coulometry at platinum gauze electrode. The redox process of the ligands was highly irreversible, whereas redox process of Cu(Ⅱ) and Ni(Ⅱ) complexes was observed as one electron transfer process of quasi-reversible and diffusion-controlled reaction. Also the electrochemical redox potentials of complexes were affected by chelate ring size of ligands. The diffusion coefficients of Cu(Ⅱ) and Ni(Ⅱ) complexes in DMF solution were determined to be 4.2-6.6×10-6 cm2/sec. Also the exchange rate constants were determined to be 3.6-9.7×10-2 cm/sec.

Low-Level Laser Therapy including Laser Acupuncture for Non-Specific Chronic Low Back Pain : Protocol for a Systematic Review

  • Yeum, Hyewon;Nam, Dongwoo
    • Journal of Acupuncture Research
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    • v.36 no.4
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    • pp.251-255
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    • 2019
  • Background: Low-level laser therapy (LLLT) including laser acupuncture (LA) has been widely used to treat chronic low back pain (CLBP), but there is no critically appraised evidence of the potential benefits. The purpose of this protocol for a systematic review was to enable the evaluation of the effectiveness of LLLT including LA for non-specific CLBP to identify the potential benefits. Methods: The electronic databases MEDLINE (PubMed), Embase (Ovid), the Cochrane Central Register of Controlled Trials (CENTRAL), Korean medical databases (KoreaMed, KMBASE, KISS, NDSL, KISTI, OASIS), the Chinese database (CNKI), and Japanese databases (CiNII, J-STAGE) are recommended. Results: Randomized controlled trials in LLLT including LA should be included in the searches. All data synthesis and subgroup analyses should be conducted using a Review Manager software. The Cochrane risk of bias tool can be used to evaluate methodological quality of the studies. A risk ratio or mean difference with a 95% confidence interval will show the effects of LLLT including LA. Conclusion: The primary outcome would be pain intensity and functional status/disability due to low back pain. The secondary outcome would be a global measurement of recovery or improvement, quality of life and adverse event.

Synthesis and Electrochemical Studies of Ni(Ⅱ) Complexes with Tetradentate Schiff Base Ligands

  • 정병구;임채평;국성근;조기형;최용국
    • Bulletin of the Korean Chemical Society
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    • v.17 no.2
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    • pp.173-179
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    • 1996
  • A series of tetradentate Schiff base ligands; [1,2-bis(naphthylideneimino)ethane, 1,3-bis(naphthylideneimino)propane, 1,4-bis(naphthylideneimino)butane, and 1,5-bis(naphthylideneimino)pentane] and their Ni(Ⅱ) complexes have been synthesized. The properties of these ligands and their Ni(Ⅱ) complexes have been characterized by elemental analysis, IR, NMR, UV-vis spectra, molar conductance, and thermogravimetric analysis. The mole ratio of Schiff base to Ni(Ⅱ) metal was found to be 1:1. The electrochemical redox process of the ligands and their Ni(Ⅱ) complexes in DMF and DMSO solution containing 0.1 M tetraethyl ammonium perchlorate (TEAP) as a supporting electrolyte have been investigated by cyclic voltammetry, chronoamperometry, differential pulse voltammetry, and controlled potential coulometry at glassy carbon electrode. The redox process of the ligands was highly irreversible, whereas redox process of Ni(Ⅱ) complexes were observed as one electron transfer process in quasi-reversible and diffusion-controlled reaction. The electrochemical redox potentials of the Ni(Ⅱ) complexes were affected by the chelate ring size of ligands. The diffusion coefficients of Ni(Ⅱ) complexes containing 0.1 M TEAP in DMSO solution were determined to be 5.7-6.9 × 10-6 cm2/sec. Also the exchange rate constants were determined to be 1.8-9.5 × 10-2 cm2/sec. These values were affected by the chelate ring size of ligands.

Chuna Manual Therapy for Cerebral Palsy in Children: A Systematic Review and Meta-analysis (소아 뇌성마비에 대한 추나 요법의 효과: 체계적 문헌고찰과 메타분석)

  • Nam, Hyun seo;Han, Seung hee;An, Da young;Baek, Tae hyun
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.16 no.2
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    • pp.29-38
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    • 2021
  • Objectives This study was aimed to evaluate the effects of Chuna manual therapy (CMT) for the treatment of cerebral palsy. Methods The randomized controlled trials (RCTs) on the treatment of CMT for cerebral palsy in children were selected among the literature published until January 2021 in seven databases. The quality of the literature was evaluated using the Cochrane's risk of bias tool, and RevMan 5.3 was used for the synthesis of results. Results Total 801 pediatric patient with cerebral palsy incontinence were finally selected from twelve RCTs. The total effective rate of the combined treatment general rehabilitation and CMT is statistically significantly higher (P<0.0001) than that of general rehabilitation alone. Conclusions This study suggests that general rehabilitation combined with CMT for cerebral palsy in children might be more effective in improving symptoms than general rehabilitation alone. As the number and quality of the literature included in the meta-analysis was insufficient, high-quality clinical studies on CMT for cerebral palsy would be required.

KIER Liquefaction R & D's status (KIER 액화 기술 개발 현황)

  • Yang, Jung-Il;Yang, Jung Hoon;Lee, Ho-Tae;Chun, Dong Hyun;Kim, Hak-Joo;Jung, Heon
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.110.1-110.1
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    • 2010
  • A bench scale slurry bubble column reactor (SBCR) with active-Fe based catalyst was developed for the Fischer-Tropsch synthesis (FTS) reaction. Considering the highly exothermic reaction heat generated in the bench scale SBCR, an effective cooling system was devised consisting of a U-type dip tube submerged in the reactor. Also, the physical and chemical properties of the catalyst were controlled so as to achieve high activity for the CO conversion and liquid oil ($C_{5+}$) production. Firstly, the FTS performance of the FeCuK/$SiO_2$ catalyst in the SBCR under reaction conditions of $265^{\circ}C$, 2.5 MPa, and $H_2/CO=1$ was investigated. The CO conversion and liquid oil ($C_{5+}$) productivity in the reaction were 88.6% and 0.226 $g/g_{cat}-h$, respectively, corresponding to a liquid oil ($C_{5+}$) production rate of 0.03 bbl/day. To investigate the FTS reaction behavior in the bench scale SBCR, the effects of the space velocity and superficial velocity of the synthesis gas and reaction temperature were also studied. The liquid oil production rate increased upto 0.057 bbl/day with increasing space velocity from 2.61 to 3.92 $SL/h-g_{Fe}$ and it was confirmed that the SBCR bench system developed in this research precisely simulated the FTS reaction behavior reported in the small scale slurry reactor.

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Synthesis and Characterization of Poly(Urethane-Methyl methacrylate) Hybrid Emulsion as a Plastic Coating Resin (플라스틱 코팅용 Poly(Urethane-MMA) 혼성 에멀젼 합성 및 특성 연구)

  • Yeom, Ji-Yoon;Baek, Kyung-Hyun;Lee, Jun-Young;Yi, Gyoung-Bae;Yoo, Byung-Won;Kim, Jung-Hyun
    • Journal of Adhesion and Interface
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    • v.8 no.1
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    • pp.8-14
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    • 2007
  • Poly(urethane-methyl methacrylate) hybrid emulsions can be controlled with their thermal, mechanical and anti-chemical properties as plastic coating materials. In this study, water dispersed poly(urethane-methyl methacrylate) hybrid emulsions were prepared by prepolymer synthesis and soap free emulsion polymerization. For imparting hydrophilicity on polyurethane prepolymer, 2,2-bis (hydroxymethyl) propionic acid was added to the polyurethane prepolymer with methyl methacrylate monomer and was neutralizated by triethylamine (TEA). After neutralization, the prepolymer mixture was dispersed in the water phase with stable droplets. The synthesis was carried out with chain extension from the ethylene diamine and initiation of methyl methacrylate by soap free emulsion polymerization. Stable poly(urethane-methyl methacrylate) hybrid emulsion was successfully obtained with different synthetic conditions and acrylic monomer contents. Poly(urethane-methyl methacrylate) hybrid emulsion were characterized and compared with tensile strength, viscosity, and adhesion properties.

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Short-term protein intake increases fractional synthesis rate of muscle protein in the elderly: meta-analysis

  • Gweon, Hyun-Soo;Sung, Hee-Ja;Lee, Dae-Hee
    • Nutrition Research and Practice
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    • v.4 no.5
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    • pp.375-382
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    • 2010
  • The precise effects of protein intake on fractional synthesis rate (FSR) of muscle protein are still under debate. The sample size of these studies was small and the conclusions in young and elderly subjects were inconsistent. To assess the effect of dietary protein intake on the FSR level, we conducted a meta-analysis of controlled protein intake trials. Random-effects models were used to calculate the weighted mean differences (WMDs). Ten studies were included and effects of short-term protein intake were evaluated. In an overall pooled estimate, protein intake significantly increased the FSR (20 trials, 368 participants; WMD: 0.025%/h; 95%CI: 0.019-0.031; P < 0.0001). Meta-regression analysis suggested that the protein dose was positively related to the effect size (regression coefficient = 0.108%/h; 95%CI: 0.035, 0.182; P = 0.009). A subgroup analysis indicated that protein intake significantly increased FSR when the protein dose was ${\leq}$ 0.80 g/kg BW (16 trials, 308 participants; WMD: 0.027%/h; 95%CI: 0.019-0.031; P < 0.0001), but did not affect FSR when the protein dose was > 0.80 g/kg BW (4 trials, 60 participants; WMD: 0.016%/h; 95%CI: 0.004-0.029; P = 0.98). In conclusion, this study is the first integrated results showing that a short-term protein intake is effective at improving the FSR of muscle protein in the healthy elderly as well as young subjects. This beneficial effect seems to be dose-dependent when the dose levels of protein range from 0.08 to 0.80 g/kg BW.

Size Tailored Nanoparticles of ZrN Prepared by Single-Step Exothermic Chemical Route

  • Lee, Sang-Ki;Park, Kyung-Tae;Ryu, Hong-Youl;Nersisyan, Hayk H.;Lee, Kap-Ho;Lee, Jong-Hyeon
    • Korean Journal of Materials Research
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    • v.22 no.5
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    • pp.243-248
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    • 2012
  • ZrN nanoparticles were prepared by an exothermic reduction of $ZrCl_4$ with $NaN_3$ in the presence of NaCl flux in a nitrogen atmosphere. Using a solid-state combustion approach, we have demonstrated that the zirconium nitride nanoparticles synthesis process can be completed in only several minutes compared with a few hours for previous synthesis approaches. The chemistry of the combustion process is not complex and is based on a metathesis reaction between $ZrCl_4$ and $NaN_3$. Because of the low melting and boiling points of the raw materials it was possible to synthesize the ZrN phase at low combustion temperatures. It was shown that the combustion temperature and the size of the particles can be readily controlled by tuning the concentration of the NaCl flux. The results show that an increase in the NaCl concentration (from 2 to 13 M) results in a temperature decrease from 1280 to $750^{\circ}C$. ZrN nanoparticles have a high surface area (50-70 $m^2/g$), narrow pore size distribution, and nano-particle size between 10 and 30 nm. The activation energy, which can be extracted from the experimental combustion temperature data, is: E = 20 kcal/mol. The method reported here is self-sustaining, rapid, and can be scaled up for a large scale production of a transition metal nitride nanoparticle system (TiN, TaN, HfN, etc.) with suitable halide salts and alkali metal azide.

Formation of Fe Aluminide Multilayered Sheet by Self-Propagating High-Temperature Synthesis and Diffusion Annealing (고온자전반응합성과 확산 열처리를 이용한 FeAl계 금속간화합물 복합판재의 제조)

  • Kim, Yeon-Wook;Yun, Young-Mok
    • Korean Journal of Materials Research
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    • v.18 no.3
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    • pp.153-158
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    • 2008
  • Fe-aluminides have the potential to replace many types of stainless steels that are currently used in structural applications. Once commercialized, it is expected that they will be twice as strong as stainless steels with higher corrosion resistance at high temperatures, while their average production cost will be approximately 10% of that of stainless steels. Self-propagating, high-temperature Synthesis (SHS) has been used to produce intermetallic and ceramic compounds from reactions between elemental constituents. The driving force for the SHS is the high thermodynamic stability during the formation of the intermetallic compound. Therefore, the advantages of the SHS method include a higher purity of the products, low energy requirements and the relative simplicity of the process. In this work, a Fe-aluminide intermetallic compound was formed from high-purity elemental Fe and Al foils via a SHS reaction in a hot press. The formation of iron aluminides at the interface between the Fe and Al foil was observed to be controlled by the temperature, pressure and heating rate. Particularly, the heating rate plays the most important role in the formation of the intermetallic compound during the SHS reaction. According to a DSC analysis, a SHS reaction appeared at two different temperatures below and above the metaling point of Al. It was also observed that the SHS reaction temperatures increased as the heating rate increased. A fully dense, well-bonded intermetallic composite sheet with a thickness of $700\;{\mu}m$ was formed by a heat treatment at $665^{\circ}C$ for 15 hours after a SHS reaction of alternatively layered 10 Fe and 9 Al foils. The phases and microstructures of the intermetallic composite sheets were confirmed by EPMA and XRD analyses.

Synthesis of Polymers in Supercritical Carbon Dioxide (초임계 유체를 이용한 고분자 합성 연구)

  • Lee, Hyun-Suk;Kim, Jin-Woong
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.36 no.1
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    • pp.17-32
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    • 2010
  • This review shows the design and the development of new $CO_2$-soluble hydrocarbon copolymers which can be used as effective stabilizers for successful dispersion polymerizations of bio-compatible materials in supercritical carbon dioxide ($scCO_2$). The basic concepts of supercritical fluid including its solvent properties and applications in polymer synthesis are described. We report the facile synthesis of highly soluble hydrocarbon based copolymers, prepared with good control via controlled free radical polymerization from readily accessible and commercially available monomers. The phase behaviour of these materials was monitored in pure $CO_2$ to investigate how the molecular weights and the composition of the copolymers affect their solubility in $CO_2$. Their activity as a stabilizer was then tested in dispersion polymerization of N-vinyl pyrrolidone in $CO_2$ at various reaction conditions to identify the key parameters required for a successful dispersion stabilization of growing PVP particles. Some prospective potentials of this research which can be applied in developing new polymer materials in an environmentally-friendly fashion for use in cosmetics are also discussed.