• Title/Summary/Keyword: Ni complex

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Effects of Complex Agents and pH on the Deposition Behavior of Electroless Ni-Co-P Film (착화제와 pH가 무전해 Ni-Co-P 도금 피막의 석출거동에 미치는 영향)

  • Choi, Byuck-Keun;Yang, Seung-Gi;Shin, Ji-Wung;Hwang, Woon-Suk
    • Corrosion Science and Technology
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    • v.13 no.3
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    • pp.107-111
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    • 2014
  • Electroless plated Ni-Co-P films have been used to suppress the electromagnetic waves from magnetic recording media, and the suppression is known to be achieved with films made with optimized plating composition and plating condition. Effects of complexing agents on the deposition rate and bath stability of Ni-Co-P film were studied using sodium citrate, sodium tartrate and multi-complex agents containing both of them. Deposition of electroless Ni-Co-P platings was dependent upon the complexing agents. Deposition rate was twice when using sodium tartrate compared to that using sodium citrate. And it was slightly slower with multi-complex agents than with sodium tartrate, bath stability being declined in the former. Deposition rate increased with increasing pH until pH 11. Excellent bath stability and good deposition rate were obtained using multi-complex agent as sodium citrate 0.10 mol/L and sodium tartrate 0.15 mol/L in the electroless Ni-Co-P plating films.

NMR Studies of Ni-binding Luteinizing Hormone Releasing Hormone

  • Kim, Jin;Won, Ho-Shik
    • Journal of the Korean Magnetic Resonance Society
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    • v.13 no.2
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    • pp.143-153
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    • 2009
  • Luteinizing Hormone Releasing Hormone (LHRH) is composed of 10 amino acids, and is best known as a neurotransmitter. Because of the 80% homology in animals, much more concerns have focused on the substances that have similar functions or can control LHRH. Ni, Cu-LHRH complexes were synthesized. The degree of complexation was monitored by $^1H,\;^{13}C$-NMR chemical shifts, and final products were identified by ESI-Mass spectrum. Solution-state structure determination of Ni-LHRH complex was accomplished by using NMR results and NMR-based distance geometry (DG). Interproton distances from nuclear Overhauser effect spectroscopy (NOESY) were utilized for the molecular structure determination. Results were compared with previous structures obtained from energy minimization and other spectroscopic methods. Structure obtained in this study has a cyclic conformation which is similar to that of energy minimized, and exhibits a specific a-helical turn with residue numbers (2~7) out of 10 amino acids. Comparison of chemical shifts and EPR studies of Ni, Cu-LHRH complexes exhibit that Ni-LHRH complex has same binding sites with the 4-coordination mode as in Zn-LHRH complex.

Variation of the Relaxation Time for NiCuZn Ferrites with Magnetic Properties

  • Nam, Joong-Hee;Oh, Jae-Hee
    • Journal of Magnetics
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    • v.1 no.1
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    • pp.37-41
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    • 1996
  • The frequency dependence of complex permeability for various NiCuZn ferrites was investigated. The variation of complex permeability for NiCuZn ferrites can be presented as a form of a semi-circle, so called the Cole-Cole plot, and the relaxation phenomena were explained with various shapes of the plots. The relaxation time $\Upsilon$ was calculated from $f_rx$, which is a relaxation frequency at ${\mu"}_{max}$. Relations between anisotropy field $H_A$ and relaxation time $\Upsilon$, initial permeability $\mu_i$ and $H_A$ were plotted to identify the frequency dependence of complex permeability.lity.

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Anti-inflammatory and Anti-itching Effects of Herbal Medicine Complex Extracts(NI-01) (한약복합추출물(NI-01)의 항염증 및 소양감 억제 효과)

  • Kim, Hyun-A;Kim, Suk-Kyung;Kim, Bae-Hwan
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.34 no.6
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    • pp.341-347
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    • 2020
  • The purpose of this study was to investigate the possibility of herbal medicine complex extract (NI-01), which were prepared from 6 natural materials (Cinnamomum cassia Blume, Lonicerae Flos, Paeonia suffruticosa Andrews, Arctium lappa Linne, Schzandra chinesis Bailon, Elsholtzia ciliata Hylander), as a functional material for inhibition of atopic dermatitis. anti-oxidative activity was confirmed by measuring DPPH electron donating ability and ABTS+ radical scavenging ability. Cytotoxicity and NO inhibition were measured using RAW 264.7 cells to confirm anti-inflammatory efficacy. The test substance was orally administered to the pruritus-induced ICR mice to confirm the inhibition of pruritus. The bovine cornea opacity and permeability (BCOP) assay was performed to confirm safety for irritation. NI-01 showed high antioxidant activity in DPPH and ABTS+ methods. In the anti-inflammatory effect tests with RAW 264.7 cells, NO production was inhibited at NI-01 concentrations of 50 (14.9%) and 100 (4.2%) ㎍/mL, which indicated that the anti-inflammatory effect was increased in a concentration-dependent manner. NI-01 also showed anti-itching effect after inducing of itching by compound 48/80 in ICR mice. NI-01 was proved to be a non-irritant substance in BCOP assay. The results of this study suggested that the herbal medicine combined extract (NI-01) has high antioxidant, anti-inflammatory and anti-itching effects, and safety for irritation. Therefore, herbal medicine complex extract (NI-01) is thought to be highly applicable for the inhibitory ingredients of the atopic dermatitis.

Spectroscopic characterization of N,N'-bis(salicylidene)pentane-1,3-diamine nickel(II) complex

  • Kim, Gilhoon;Won, Hoshik
    • Journal of the Korean Magnetic Resonance Society
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    • v.18 no.2
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    • pp.74-81
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    • 2014
  • The $N_2O_2$ tetradentate Schiff base ligand, N,N'-bis(salicylidene)pentane-1,3-diamine (Salpn), coupled with 1:2 concentration ratio of 1,3-diaminopentane and salicylaldehyde was used to produce a series of macrocyclic Nikel(II) complexes. In the metal complexation, it was observed that Salpn macrocyclic ligand can adopt more than a metal ion giving an unique multinuclear metal complexes including Ni(II)Salpn and $Ni(II)_3(Salpn)_2$. Characteristic IR ${\upsilon}(M-O)$ peaks for Ni(II)Salpn and $Ni(II)_3(Salpn)_2$ were observed to be $1028cm^{-1}$ and $1024cm^{-1}$, respectively. Characteristic UV-Vis absorption ${\lambda}_{max}$ peaks for $Ni(II)_3(Salpn)_2$ were observed to be 241nm and 401 nm. Structural characterization of $Ni(II)_3(Salpn)_2$ by NMR exhibits that the salicylidene ring moiety has two different resonance signals originated from the magnetically asymmetric diligand and trinuclear bis complex. Complete NMR signal assignments and characterizations elucidating structural features of $Ni(II)_3(Salpn)_2$ were described in detail.

EPR Studies of the Active Sites of Carbon Monoxide Dehydrogenase from Clostridium thermoaceticum

  • Shin, Woonsup;Lindahl, Paul A.
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.869-876
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    • 1995
  • The active sites of the nickel and iron-containing enzyme, carbon monoxide dehydrogenase (CODH) from clostridium thermoaceticum were investigated using Electron Paramagnetic Resonance (EPR) technique. CODH exhibits several spectral features called NiFeC, $g_{ave}=1.82$, $g_{ave}=1.86$. FCII signals which are originated from different clusters in this enzyme. CODH is know to catalyze two different kinds of reactions - acetyl-CoA synthesis and CO oxidation. The acetyl-CoA synthesis activity can be followed by monitoring CO/acetyl-CoA exchange. The addition of 1,10-phenanthroline (phen) to CODH selectively destroyed the CO/acetyl-CoA exchange activity and eliminated the NiFeC signal completely. CO oxidation activity and other EPR signals were unaffected. Such behavior demonstrates that CODH has two distinct active sites and that the NiFe complex is only responsible for the CO/acctyl-CoA exchange activity. Phen caused the removal of only 30% of Ni in the NiFe complex ($0.3Ni/{\alpha}{\beta}$) as shown by the quantitative metal analysis. The phen-treated CODH could be reactivated fully by incubation In $Ni^{2+}$ solution. Radioactive $^{63}Ni^{2+}$ was used to quantitate the amount of the $Ni^{2+}$ incorporated into phen-treated enzyme and showed that the amount was the same as the removed by the phen treatment. i.e. $0.3Ni/{\alpha}{\beta}$. This indicates that only 30% of NiFe complexes are labile and responsible for the CO/acctyl-CoA exchange activity, the other 70% are non-labile and have no exchange activity. This is the first clear evidence that the NiFe complex is heterogencous and labile and non-labile Ni sites arc interacting differently with substrates and chelating agents like phen.

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Synthesis and Characterization of Nickel(II) Tetraaza Macrocyclic Complex with 1,1-Cyclohexanediacetate Ligand

  • Lim, In-Taek;Kim, Chong-Hyeak;Choi, Ki-Young
    • Journal of the Korean Chemical Society
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    • v.62 no.6
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    • pp.427-432
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    • 2018
  • The reaction of [$[Ni(L)]Cl_2{\cdot}2H_2O$ (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[$14,4,0^{1.18},0^{7.12}$]docosane) with 1,1-cyclohexanediacetic acid ($H_2cda$) yields mononuclear nickel(II) complex, [$Ni(L)(Hcda^-)_2$] (1). This complex has been characterized by X-ray crystallography, electronic absorption, cyclic voltammetry and thermogravimetric analyzer. The crystal structure of 1 exhibits a distorted octahedral geometry with four nitrogen atoms of the macrocycle and two 1,1-cyclohexanediacetate ligands. It crystallizes in the triclinic system P-1 with a = 11.3918(7), b = 12.6196(8), $c=12.8700(8){\AA}$, $V=1579.9(2){\AA}^3$, Z = 2. Electronic spectrum of 1 also reveals a high-spin octahedral environment. Cyclic voltammetry of 1 undergoes one wave of a one-electron transfer corresponding to $Ni^{II}/Ni^{III}$ process. TGA curve for 1 shows three-step weight loss. The electronic spectra, electrochemical and TGA behavior of the complex are significantly affected by the nature of the axial $Hcda^-$ ligand.

Production of the ultra fine-composite powders of WC-Co and WC-Ni (초미립의 탄화 텅스텐-코발트와 탄화 텅스텐-니켈 복합분말의 제조)

  • 김병재;윤병하
    • Journal of the Korean institute of surface engineering
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    • v.26 no.2
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    • pp.87-107
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    • 1993
  • The grain size of the final products of WC-Co and WC-Ni composite powders is dependent on the size of the starting material and the conditions employed for the reduction and carburization. APT-Co and -Ni com-plex salts were prepared by the substitution reaction between ammonium ions in APT and the metal ions in Co(NO3)2 and Ni(NO3)2 solutions of different concentrations(0.1 to 0.7M) at $50^{\circ}C$ and the grain sizes of the com-plex salts was $0.54~0.76\mu\textrm{m}$. The complex which calcined the complex salts at $700^{\circ}$~80$0^{\circ}C$ for 60min. were 0.2~0.5$\mu\textrm{m}$. W-Co($5.92^{\circ}C$) and -Ni(6.95%) powders which reduced the complex oxides with H2d atmo-sphere(flow rate;600cc/min.) at $700^{\circ}$~$800^{\circ}C$ for 60min. were $0.5~0.6\mu\textrm{m}$. The mean grain sizes of WC-Co and WC-Ni composite powders which carburized both complex metals of W-Co and W-Ni at $800^{\circ}C$ for 60min. were $0.5~0.6\mu\textrm{m}$, and take place the coarsening of the grain above $800^{\circ}C$ and the optmium ratio of C3H8 and H2 was 0.2 for the control of the free carbon. The effect of Co contents on the particle sizes decreased from 0.4 to $0.25\mu\textrm{m}$ with increasing the content from 2.0 to 7.6w%. The activation energies on the reductions of oxides and the formations of carbides were as follows ; W-Co : Q = 8.7 kcal/mole, W-Ni : Q = 8.1 kcal/mole, WC-Co pow-der : Q = 17.8 kcal/mole, WC-Ni powder : Q = 16.6 kcal/mole.

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Kinetic and Equilibrium Studies on Complex Formation Between Ni(II) and D-Penicillamine in Aqueous Media (Ni(II)와 D-Penicillamine과의 착물형성반응에 대한 속도론적 및 평형에 관한 연구)

  • Yong-Kyu Kim;Sung-Nak Choi
    • Journal of the Korean Chemical Society
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    • v.30 no.5
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    • pp.475-482
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    • 1986
  • Rates and equilibriurn of complex formation between $Ni^{2+}$ and D-penicillamine have been investigated in aqueous solutions. Kinetic study on the complex formation were performed in the pH range of 8∼9 by the use of pressure-jump technique. D-Penicillamine coordinates to the nickel(II) ion utilizing sulfur and nitrogen as donor atoms in the high pH condition (pH 9.2). However, in the pH range of 8.25∼9.07, the stepwise stability constant becomes drastically reduced and the undissociated mercapto group does not participate in bonding. The rate-determining step of the complexation reaction is found to be the release of a water molecule from the inner-coordination sphere of $Ni^{2+}$ ion.

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