• Journal of the Korean Chemical Society
• /
• v.16 no.2
• /
• pp.80-83
• /
• 1972

The activity change of lysozyme resulted from its exposure to $Ti-H_2O_2$system in aqueous liquid at room temperature and to ${\gamma}$-irradiation in ice at $195^{\circ}K$ has been measured at room temperature with a Cary-14 spectrophotometer. The enzymatic activity of lysozyme which had been added to a previously flow-mixed solution of $TiCl_3$ and $H_2O_2$ (System I) was compared with the activity of a lysozyme-$H_2O_2$ solution after flow-mixing with $TiCl_3$ (System II), considering the differences between these two activity changes as the extent of the enzymatic inactivation by the involvement of OH radical reaction. The fraction of lysozyme inactivated by OH radical in the system containing 0.0025 M $TiCl_3-0.1M$ $H_2O_2$ (ph 3.5) was 13%, When the $TiCl_3$ concentration is double (pH 3.0), the fraction of enzyme inactivated increases to 36%. The activity of the system containing 0.025 M $TiCl_3-0.1$ M $H_2O_2$ (pH 1.5) was essentially zero. The results seem to support the previos view that the production of OH radical should be proportional to $TiCl_3$ concentration when $H_2O_2$ is present in excess. Increase in the extent of inactivation found in system I with increasing $TiCl_3$ concentration may be due to a pH effect. $H_2O_2$ seems to be less effective than $TiCl_3$ in the inactivation. 1% lysozyme solution, when ${\gamma}$-irradiated with a total dose of 3M rads, loses about 20% of its activity. Lowering of temperature also was found to yield a reduction in enzymatic activity.

• Journal of Powder Materials
• /
• v.24 no.1
• /
• pp.41-45
• /
• 2017

The effects of the heat treatment temperature and of the atmosphere on the dehydrogenation and hydrogen reduction of ball-milled $TiH_2-WO_3$ powder mixtures are investigated for the synthesis of Ti-W powders with controlled microstructure. Homogeneously mixed powders with refined $TiH_2$ particles are successfully prepared by ball milling for 24h. X-ray diffraction (XRD) analyses show that the powder mixture heat-treated in Ar atmosphere is composed of Ti, $Ti_2O$, and W phases, regardless of the heat treatment temperature. However, XRD results for the powder mixture, heat-treated at $600^{\circ}C$ in a hydrogen atmosphere, show $TiH_2$ and TiH peaks as well as reaction phase peaks of Ti oxides and W, while the powder mixture heat-treated at $900^{\circ}C$ exhibits only XRD peaks attributed to Ti oxides and W. The formation behavior of the reaction phases that are dependent on the heat treatment temperature and on the atmosphere is explained by thermodynamic considerations for the dehydrogenation reaction of $TiH_2$, the hydrogen reduction of $WO_3$ and the partial oxidation of dehydrogenated Ti.

• Journal of Powder Materials
• /
• v.23 no.4
• /
• pp.282-286
• /
• 2016

A sintered body of $TiB_2$-reinforced iron matrix composite ($Fe-TiB_2$) is fabricated by pressureless-sintering of a mixture of titanium hydride ($TiH_2$) and iron boride (FeB) powders. The powder mixture is prepared in a planetary ball-mill at 700 rpm for 3 h and then pressurelessly sintered at 1300, 1350 and $1400^{\circ}C$ for 0-2 h. The optimal sintering temperature for high densities (above 95% relative density) is between 1350 and $1400^{\circ}C$, where the holding time can be varied from 0.25 to 2 h. A maximum relative density of 96.0% is obtained from the ($FeB+TiH_2$) powder compacts sintered at $1400^{\circ}C$ for 2 h. Sintered compacts have two main phases of Fe and $TiB_2$ along with traces of TiB, which seems to be formed through the reaction of TiB2 formed at lower temperatures during the heating stage with the excess Ti that is intentionally added to complete the reaction for $TiB_2$ formation. Nearly fully densified sintered compacts show a homogeneous microstructure composed of fine $TiB_2$ particulates with submicron sizes and an Fe-matrix. A maximum hardness of 71.2 HRC is obtained from the specimen sintered at $1400^{\circ}C$ for 0.5 h, which is nearly equivalent to the HRC of conventional WC-Co hardmetals containing 20 wt% Co.

• Korean Journal of Materials Research
• /
• v.10 no.11
• /
• pp.732-737
• /
• 2000

Plasma enhanced chemical vapor deposition of $TiO_{2$\pm}{\delta}$ has been carried out using TEMAT [tetrakis(ethylmethylamido) titanium] and $H_2$. Increasing the power from 300 W to 500 W produced the high density plasma, leading to the formation of TiO$_2$films with an increased ratio of Ti to O and a negligible amount of C and N. Applying the bias of 30W to the substrate in creased the growth rate of the film with a slightly increased content of Ti in the film. In addition, $H_2O$ was from either the residual gas in the gase pressure or $H_2(/He)$ gas and actively participated in the formation of $TiO_2$ films. Consequently, Ti ions created in the plasma could be a main contributor to $TiO_2$ formation with a slight amount of $H_2O(~10^{-4}Toor)$ in the ambient, which provided the dissociation of TEMAT.

• Journal of the Korean Chemical Society
• /
• v.38 no.1
• /
• pp.55-60
• /
• 1994

Molecular orbital calculations at the extended Huckel level have been carried out for $Cp_2TiSiHPh(1),\;[Cp_2Ti]_2[{\mu}-HSi(HPh)][{\mu}-H] (2),\;and\;[Cp_2TiSiH_2Ph]_2$ (3) complexes which are important intermediates in organosilane polymerization. Stable geometry of complex 1 is not $C_{2V}$, but Cs symmetry and the rotational energy barrier of $SiH_2$ unit is computed to be 14 kcal/mol. The orbital interaction diagrams are studied to characterize the chemical bonding for the electron deficient systems, 2 and 3. It is possible for Si-H to be coordinated to the Ti metal using $\sigma$ bonding.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.120-120
• /
• 2003

MOCVD법으로 TiN 표면에 Ru을 증착함에 있어서 Ru의 핵생성을 고양시키기 위한 ECR plasma 전처리 세정이 필요하다. 본 연구에서는 Ru 증착시 ECR $H_2O$$_2$, AE Plasma 전처리 세정 효과를 SEM, AES, XRD로 분석하였다. Ru의 핵생성은 ECR H$_2$, Ar Plasma의 노출시간이 증가할수록 향상된 반면, ECR $O_2$ plasma의 경우 노출시간이 증가할수록 핵생성 효과는 감소하였다. H$_2$ plasma 내의 H$_2$ion은 Ti와 NH$_3$를 형성하기 위해서 TiN과 반응하여 TiN을 Ti로 개질 시켰으며, Ar plasma 전처리 세정하는 동안 Ar plasma 내의 Ar ion은 TiN 또는 TiON 표면의 질소와 산소원자를 제거하는 효과를 나타내었다. 그 결과 TiN 표면상에서도 Ru의 핵생성이 쉽게 이루어졌으며 H$_2$, Ar ECR Plasma 전처리 세정에서 RU 핵생성이 향상되는 결과를 얻었다. 세 종류의 plasma중에서 Ar ECR plasma로 전처리 세정한 경우에 가장 높은 Ru 핵생성 밀도를 얻을 수 있었다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.2
• /
• pp.91-95
• /
• 2002

$TiO_2$ nanopowder was successfully prepared using a titanium tetra-isopropoxide. Subsequently, the effect of pH on the characteristics of the prepared $TiO_2$ nanopowder was evaluated depending on the amounts of the catalysts such as HCI and NH40H. The morphology and phase transformation of $TiO_2$ powder prepared by hydrolysis of titanium tetraisopropoxide were strongly influenced by the presence of the catalysts. In the case of using $NH_4$OH, the morphology of the $TiO_2$ powder exhibited powder form. For the HCI catalyst, it showed bulk or granule form. The phase transformations of amorphous $Ti(OH)_4$ to anatase $TiO_2$ and the anatase to rutile was significantly influenced by the kind and amount of the catalysts.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.1
• /
• pp.49-54
• /
• 1998

$BaTiO_3$ fine particles were synthesized by hydrothermal method. $TiO_2$ and $Ba(OH)_2{\cdot}8H_2O$ were used as staring materials, and it was possible to synthesize $BaTiO_3$ fine particles in pure water by using excess $Ba(OH)_2{\cdot}8H_2O$. The shape of synthesized particles are irregular but near spherical, and the particle size depends on the temperature and Ba/Ti atomic ratio.

• Journal of the Korean Ceramic Society
• /
• v.32 no.7
• /
• pp.809-816
• /
• 1995

Ti1-xAlxN films were successfully deposited on high speed steel and silicon wafer by plasma-assisted chemical vapor deposition using a TiCl4/AlCl3/N2/Ar/H2 gas mixture. Plasma process enabled N2 gas to nitride AlCl3, which is not possible in sense of thermodynamics. XPS analyses revealed that the deposited layer contained Al-N bond as well as Ti-N bond. Ti1-xAlxN films were polycrystalline and had single phase, B1-NaCl structure of TiN. Interplanar distance, d200, of (200) crystal plane of Ti1-xAlxN was, however, decreased with Al content, x. Al incorporation into TiN caused the grain size to be finer and changed strong (200) preferred orientation of TiN to random oriented microstructure. Those microstructural changes with Al addition resulted in the increase of micro-hardness of Ti1-xAlxN film up to 2800Kg/$\textrm{mm}^2$ compared with 1400Kg/$\textrm{mm}^2$ of TiN.

• Journal of the Korean Ceramic Society
• /
• v.36 no.7
• /
• pp.691-697
• /
• 1999

TiO2 powder was adsorbed on the surface of mica using the heterocoagulation method in water TiO2 powder was prepared from hydrolysis of titanium-iso propoxide in a mixed solvent of anhydrous ethanol and water. When the molar ratio of water to titanium iso-propoxide was 0.25 monodispersed spherical TiO2 particles were obtained. The prepared TiO2 powder showed anatase phase after heat treatment at 50$0^{\circ}C$ for 2 h and then transformed to rutile phase after heat treatment at 100$0^{\circ}C$ for 2h. The iso-electric points of TiO2 and Mica were pH 3.9 and pH 3.25 respectively which were measured by the Z-potential analysis in water base. The maximum Z-potential difference between two powders was observed in the range of pH 3.6~3.7 TiO2 powder was adsorbed on the surface of mica by heterocoagulation method in pH 3.6~3,7 The properties of prepared TiO2 powder was haracterized by TG-DTA, XRD and SEM The morphology and thermal properties of TiO2-adsorbed mica were examined.