1,305 research outputs found
Formation of monodisperse spherical TiO2 powders by thermal hydrolysis of Ti(SO4)(2)
No full textTitania powders have been prepared by the thermal hydrolysis of titanium sulfate at 80 degrees C in a mixed solvent of n-propyl alcohol (n-PrOH) and water The morphology of the powders was greatly influenced by the volume ratio in n-PrOH to water (RH ratio) of the solvent, An RH ratio of 1.0 was essential for the formation of spherical TiO2 powders, When hydroxypropyl cellulose (HPC) was used as a steric dispersant, monodisperse spherical powders 0.7 mu m in diameter mere produced. As the RH ratio was increased, the zeta potential of the powders was negatively increased and the dielectric constant of the solvent was decreased, However, powders obtained at an RH ratio of 1.0 were observed to have the highest energy barrier, The colloidal stability of the powders in a mixed solvent of n-PrOH and water is discussed, As-precipitated powders were amorphous hydrates of titania and were crystallized by calcination into anatase (>600 degrees C) and rutile (>800 degrees C)
Plasma-sprayed Al-21Ti-23Cr coating for oxidation protection of TiAl alloys
No full textTo improve the oxidation resistance of the gamma-based TiAl alloy, Al-Ti-Cr coatings approximately 150 mum in thickness were formed on Ti-48Al alloy using air plasma spraying process. The powder with the composition of Al-21Ti-23Cr (at.%) were used as an Al-Ti-Cr coating material. Isothermal and cyclic oxidation tests at 1000degreesC in air were conducted to investigate the oxidation resistance of both Al-Ti-Cr coatings and of TiAl alloys with Al-Ti-Cr coatings. XRD performed the phase identification of Al-Ti-Cr coatings. After exposure at 1000degreesC in air, rutile TiO2 which resulted from the oxidation of Ti during spraying, was always found in addition to alpha-Al2O3 in the oxide scale. However, isothermal and cyclic oxidation tests of a Ti-48Al alloy coated with an Al-Ti-Cr coating showed that this coating improved the oxidation resistance of TiAl alloy at 1000degreesC. Furthermore, cyclic oxidation tests of Al-Ti-Cr coatings showed stable oxidation behavior at 1000degreesC for up to 100 h because of a high level of adhesion between the coating layer and the oxide scale although the growth rate of the oxide was relatively high. Additionally, spark plasma sinterer treatment was introduced to reduce the porosity in the coating layer, so it could be suggested that the Al-21Ti-23Cr coating was effective in enhancing the oxidation resistance of the TiAl alloy at 1000degreesC, although the porosity at coating/substrate interface must be reduced. (C) 2003 Elsevier B.V. All rights reserved
Case Study for Holylight(HK)
No full textIn this thesis the case company – Holylight (HK) was thoroughly studied. The company structure, business strategic management and Marketing mix (4ps) were analyzed using SWOT analysis. It was found that Holylight (HK) had huge poten-tial in the business its stable supplies from the United States of America, Europe and Australia; Alliance partnership company ensure the steady sales channel in potential market – China that further development and expansion are highly feasible.
However there are issues, both internal and external. T prudent strategies and lack of manpower that might hinder a smooth growth of the business. Advises and recommendations were given to tackle the issues mentioned, such as bring up a successor and entering to a new market which related to Marine industry. Hopefully the applications of them would help Holylight (HK) in the future.
Author used interview as the main researching Method. Author collected the Information which needed in this case study from the CEO directly. Observational research also apply in this case study, author worked for the case company for a not short period and it provided the information in more objective way
A medium energy ion scattering analysis of the Si-SiO2 interface formed by ion beam oxidation of silicon
No full textThe Si-SiO2 interface formed by 3 keV O-2(+) ion bombardment on silicon at room temperature and 600 degrees C was studied by in situ medium energy ion scattering spectroscopy (MEIS). The amorphization process at the initial stage of the oxygen ion bombardment and the subsequent formation of the suboxide layer and the disordered silicon layer at the Si-SiO2 interface were studied as a function of the ion dose from 2.5 X 10(15) atoms/cm(2) to 5 X 10(17) atoms/cm(2) at room temperature and 600 degrees C. After reaching the steady state, below a similar to 6 nm SiO2 layer, a similar to 2 nm suboxide layer and a similar to 3 nm disordered Si layer were observed at the Si-SiO2 interface. The annealing effect at 600 degrees C decreased the number of disordered silicon atoms and the suboxide silicon atoms, which make the Si-SiO2 interface more abrupt, was more clearly observed at the initial stage of the bombardment.Financial supports from the Center for Molecular
Science, Korea, and the Ministry of Science and
Technology, Korea, are appreciated
Impact of scalar NSI on the neutrino mass ordering sensitivity at DUNE, HK and KNO
No full textThe study of neutrino non-standard interactions (NSI) is a well-motivated phenomenological scenario to explore new physics beyond the Standard Model. The possible scalar coupling of neutrinos () with matter is one of such new physics scenarios that appears as a sub-dominant effect that can impact the -oscillations in matter. The presence of scalar NSI introduces an additional contribution directly to the -mass matrix in the interaction Hamiltonian and subsequently to the -oscillations. This indicates that scalar NSI may have a significant impact on measurements related to -oscillations e.g. leptonic CP phase , octant and neutrino mass ordering (MO). The linear scaling of the effects of scalar NSI with matter density also motivates its exploration in long-baseline (LBL) experiments. In this paper, we study the impact of a scalar-mediated NSI on the MO sensitivity of DUNE, HK and HK+KNO, which are upcoming LBL experiments. We study the impact on MO sensitivities at these experiments assuming that scalar NSI parameters are present in nature and is known from other non-LBL experiments. We observe that the presence of diagonal scalar NSI elements can significantly affect the -mass ordering sensitivities. We then also combine the data from DUNE with HK and HK+KNO to explore possible synergy among these experiments in a wider parameter space. We also observe a significant enhancement in the MO sensitivities for the combined analysis.33 pages, 16 figures, Published in JHE
Effect of pH on HK-VDAC binding.
No full text(A, B) Immunoblots (top) and quantified band intensities (bottom) of recombinant HK-1 (A) and HK-2 (B) co-immunoprecipitated with purified VDAC protein. Recombinant HK and purified VDAC protein were pre-incubated in pH 6.2 or 7.8 for 50 min. Bars are mean ± SD (n = 3) of band intensities normalized by VDAC bands relative to that at pH 6.2.</p
The electronic energy loss of 100 keV heavy ions in medium energy ion scattering analysis of a Ta2O5 ultrathin film
No full textTo optimize the depth resolution of Medium Energy Ion Scattering Spectroscopy (MEIS), a 10 nm Ta2O5 thin film on a Si(100) substrate was analyzed by MEIS using H+ and heavy ions such as Li+, N+ and Ne+ ions. The use of heavy ions such as Li+ and N+ increased the electronic stopping powers 2-3 times but it also increased the electronic straggling compared to H+ ions, For Nef ions, the ion neutralization problem was so severe that the scattering ion intensity from the subsurface layer was attenuated very rapidly and a strong doubly ionized Ne++ peak was observed. For 100 keV N+ and Ne+ ions, multiple scattering peaks were observed.The work is supported financially from the center for molecular science, south korea
A new active clamping zero-voltage switching PWM current-fed half-bridge converter
No full textA new active clamping zero-voltage switching (ZVS) pulse-width modulation (PWM) current-fed half-bridge converter (CFHB) is proposed in this paper. Its active clamping snubber (ACS) can not only absorb the voltage surge across the turned-off switch, but also achieve the ZVS of all power switches. Moreover, it can be applied to all current-fed power conversion topologies and its operation as well as structure is very simple. Since auxiliary switches in the snubber circuit are switched in a complementary way to main switches, an additional PWM IC is not necessary. In addition, it does not need any clamp winding and auxiliary circuit besides additional two power switches and one capacitor while the conventional current-fed half bridge converter has to be equipped with two clamp windings, two ZVS circuits, and two snubbers. Therefore, it can ensure the higher operating frequency, smaller-sized reactive components, lower cost of production, easier implementation, and higher efficiency. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200-W, 24-200 Vdc prototype are presented
Low sputter damage of metal single crystalline surfaces investigated with medium energy ion scattering spectroscopy
No full textIt was observed clearly that the sputter damage due to Ar+ ion bombardment on metal single crystalline surfaces is extremely low and the local surface atomic structure is preserved, which is totally different from semiconductor single crystalline surfaces. Medium energy ion scattering spectroscopy (MEIS) shows that there is little irradiation damage on the metal single crystalline surfaces such as Pt(111), Pt(100), arnd Cu(111), in contrast to the semiconductor Si(100) surfaces, for the ion energy of 3-7 keV even above 10(16)-10(17) ions/cm(2) ion doses at room temperature. However, low energy electron diffraction (LEED) spots became blurred after bombardment. Transmission Electron Microscopy (TEM) studies of a Pt polycrystalline thin film showed formation of dislocations after sputtering. Complementary MEIS, LEED and TEM data show that on sputtered single-crystal metal surfaces, metal atoms recrystallize at room temperature after each ion impact. After repeated ion impacts, local defects accumulate to degrade long range orders. (C) 1999 Elsevier Science B.V. All rights reserved.Financial supports from Ministry of Science and
Technology, Korea through Nanostructure Technology
Project and Center for Molecular Science, Korea
are appreciated
Effects of pH on co-localization of HK-1 and HK-2 with VDAC.
No full text(A,B) Confocal microscopy images of T47D cells double stained for VDAC and HK-1 (A) or VDAC and HK-2 (B) following incubation at pH 6.2 or 7.8.</p
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