• Journal of the Korean Magnetics Society
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• v.21 no.1
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• pp.37-41
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• 2011

Fe compounds of scoria samples distributed in Songdang-ri positioning north-eastern area of Jeju island were investigated by means of X-ray diffractometry (XRD) and $^{57}Fe$ M$\ddot{o}$ssbauer spectroscopy. The samples were prepared from six parasite. We found that the samples were composed of a typical olivine, pyroxene, ilmenite, $SiO_2$, anorite and anorthoclase, M$\ddot{o}$ssbauer spectrum of the most scoria samples are shown doublets and sextets of olivine, doublets of pyroxene, ilmenite and silicate minerals. And the valence states of Fe ion of the scoria samples in this area are chiefly 3+ charge state and a little 2+ charge state.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1171-1176
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• 2004

Three banana-shaped achiral compounds, 4-chloro-1,3-phenylene bis [4-{4-(undecenyloxy)phenyl imino-methyl} benzoate] derivatives, were synthesized with variation of a substituent (x=H, F, Cl); their antiferro-electric properties are described. The smectic mesophases, including a switchable chiral smectic C(Sm $C^{\ast}$) phase, were characterized by differential scanning calorimetry, polarizing optical microscopy, triangular wave method, and X-ray diffractometry. The presence of vinyl groups at the terminals of linear side wings in the banana-shaped achiral molecules induced a decrease in melting temperature and formation of the switchable Sm $C^{\ast}$ phase in the melt. The smectic phase having a lateral fluorine-substituent at 3-position of the Schiff's base moiety showed antiferroelctric switching, and the value of spontaneous polarization on reversal of an applied electric field was 250 nC/$cm^2$ .

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.114-121
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• 1997

The transparent conductiong thin films of tin oxides were prepared on pyrex glass substrates by the pulse laser deposition. In the atmospheres of vacuum, O2, and $Sn(CH_3)_4$ a polycrystalline $SnO_2$ target was ablated by Nd-YAG laser beam to deposit thin films on the substrates at room temperature, and as-deposited films were subsequently heat-treated in the air for 2 h at 230, 420 and $610^{\circ}C$, respectively. The characteristics of the thin films were examined by UV-VIS-NIR spectrometry and X-ray diffractometry, and the electrical properties were measured by four-point probe method along with film thickness monitored by the stylus method. It was observed that in the presence of $Sn(CH_3)_4$, $SnO_2$ phases were grown even at room temperature. This suggests that the microplasma producted during the laser ablation plays an important role in the dissociaation of precursor molecules.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.431-436
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• 2002

To develop a method for increasing RS level in maize starch, cross-linked resistant starches treated with annealing were prepared. Maize starch and amylomaize VII were used in the study and annealed at $40{\sim}60^{\circ}C$ before cross-linking modification. To compare effect of annealing below gelatinization temperature, starches were heat treated at 70 and $100^{\circ}C$. RS contents were assayed by pancreatin-gravimetric (P/G) method. When maize starch and amylomaize VII were cross-linked at $45^{\circ}C$ and pH 11.0 by slurrying the starch on a solution of STMP(sodium trimetaphosphate), STPP(sodium tripolyphosphate), and sodium sulfate, RS content was 14.7% and 45.3%, respectively. Annealing below gelatinization temperature before cross-linking increased RS contents of prepared cross-linked starches but did not affect the swelling power. Heat treatment above gelatinization temperature increased the swelling power of cross-linked starch prepared from maize starch. The characteristics by X-ray diffractometry and scanning electron microscopy of cross-linked resistant starch were not changed by annealing.

• Polymer(Korea)
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• v.34 no.4
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• pp.369-375
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• 2010

We used melt polymerization method to prepare a series of aromatic liquid crystals (LCs) based on aromatic ester and amide units with the reactive methyl-maleimide end group, and then the resulting thermally cross-linked LCs to produce LC thermoset films by means of solution casting and the followed heat treatment. The synthesized LCs and LCTs were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), X-ray diffractometry (XRD), and polarizing optical microscopy (POM) with a hot stage. All of the LCs prepared by melt polymerization method formed smectic mesophases. The thermal properties of the LC and LCT films were strongly affected by the mesogen units in the main chain structures. The thermal expansion coefficients of samples were in the range of 27.72~50.95 ppm/$^{\circ}C$.

• Biomaterials Research
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• v.22 no.4
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• pp.352-359
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• 2018

Background: Black phosphorus (BP) has emerged as a novel class of nanomaterials owing to its unique optical and electronic properties. BP, a two-dimensional (2D) nanomaterial, is a structure where phosphorenes are stacked together in layers by van der Waals interactions. However, although BP nanodots have many advantages, their biosafety and biological effect have not yet been elucidated as compared to the other nanomaterials. Therefore, it is particularly important to assess the cytotoxicity of BP nanodots for exploring their potentials as novel biomaterials. Methods: BP nanodots were prepared by exfoliation with a modified ultrasonication-assisted solution method. The physicochemical properties of BP nanodots were characterized by transmission electron microscopy, dynamic light scattering, Raman spectroscopy, and X-ray diffractometry. In addition, the cytotoxicity of BP nanodots against C2C12 myoblasts was evaluated. Moreover, their cell imaging potential was investigated. Results: Herein, we concentrated on evaluating the cytotoxicity of BP nanodots and investigating their cell imaging potential. It was revealed that the BP nanodots were cytocompatible at a low concentration, although the cell viability was decreased with increasing BP nanodot concentration. Furthermore, our results demonstrated that the cells took up the BP nanodots, and the BP nanodots exhibited green fluorescence. Conclusions: In conclusion, our findings suggest that the BP nanodots have suitable biocompatibility, and are promising candidates as fluorescence probes for biomedical imaging applications.

• Journal of Sericultural and Entomological Science
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• v.48 no.1
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• pp.11-15
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• 2006

Antheraea yamamai silk fibroin powder was prepared by treatment with HCl. The prepared A. yamamai fibroin hydrolysate was characterized by gel filtration chromatography, amino acid analysis, X-ray diffractometry, circular dichroism analysis, differential thermal analysis, and thermogravimetry. The average molecular weight of A. yamamai powder was about 430 and the major amino acids composed of the powder were Ala and Ser. According to XRD analysis, A. yamamai silk powder showed sharp diffraction peaks at $2{\theta}=20.34^{\circ}\;and\;31.5^{\circ}$. CD spectrum showed a peak around 220 nm and a should 215 nm, assigned to ${\alpha}-helix\;and\;{\beta}-sheet$ structure, respectively. DSC and TGA showed that the maximum degradation temperature of powder was around $250{\sim}270^{\circ}C$. Moreover, no harmful heavy metal was contained in the A. yamamai silk fibroin hydrolysate.

• Nuclear Engineering and Technology
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• v.4 no.2
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• pp.132-136
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• 1972

The mechanism for activated sintering of UO$_2$by an addition of 0.05 w/o TiO$_2$was investigated using a high temperature X-ray diffractometer. The diffraction pattern of UO$_2$pellets was studied in a temperature range from room temperature to 120$0^{\circ}C$ in hydrogen atmosphere. At 120$0^{\circ}C$, the expansion of UO$_2$lattice were 1.448% and 1.354% greater when it was compared with those at room temperature for pellets with and without the 0.05 w/o TiO$_2$addition, respectively-The effect of the TiO$_2$addition is to increase the lattice constant of UO$_2$by 0.094% at 120$0^{\circ}C$. The lattice constant at 120$0^{\circ}C$without the TiO$_2$addition is equal to that at 108$0^{\circ}C$ with the 0.05 w/o TiO$_2$addition. This temperature difference could be well compared with the suppression of sintering temperature by TiO$_2$hat had been observed Previously. It is believed that the increase in lattice expansion due to the TiO$_2$addition would give rise to the activated sintering of UO$_2$by the lattice-expansion-induced-enhancement of self diffusion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.4
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• pp.357-364
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• 2021

The present study investigated the hydration properties and NO_x-removal performances of the cement pastes containing three different types of TiO₂. Two commercially available TiO₂ (P-25 and NP-400) and refined TiO₂ (GST) obtained from waste sludge were incorporated to cement paste at levels of 0, 5, 10, and 20 wt%. Isothermal calorimetry test results indicated that the TiO₂ incorporation induced a notable influence on the reaction kinetics of cement paste, showing the highest cumulative heat release in the samples containing P-25, followed by NP-400 and GST. Quantitative X-ray diffractometry as calculated by the Rietveld method identified that the incorporated TiO₂ promoted the formation of C-S-H, ultimately leading to the enhancement in the 28 day-compressive strength of cement pastes. As revealed by SEM/EDS analysis, the content of distributed Ti elements on the surface of the samples was in the order of P-25, GST, and NP-400. Regardless, the NO_x-removal performance was the highest in the sample containing P-25, followed by NP-400 and GST.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.23-30
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• 2004

Interfacial reaction of Pb-free $Sn0.7wt{\%}Cu$ and $Sn3.8wt{\%}Ag0.7wt{\%}Cu$ solders and Pt during aging has been investigated. After the $Sn3.8wt{\%}Ag0.7wt{\%}Cu/Pt$ specimens were reflowed at $250^{\circ}C$ for 30s and the $Sn0.7wt{\%}Cu/Pt$ specimens were reflowed at $260^{\circ}C$, the specimens were aged at $125^{\circ}C,\;150^{\circ}C$ and $170^{\circ}C$ for 25-121 hours. The intermetallic thitkness and morphology change during aging were characterized using SEM, EDS and XRD. $PtSn_4$ and $PtSn_2$ were observed in the solder/pt interface and the intermetallic formation was governed by diffusion. The activation energy of intermetallic formation was 145.3 kJ/mol for$Sn3.8wt{\%}Ag0.7wt{\%}Cu/Pt$ specimens for $Sn0.7wt{\%}Cu/Pt$ specimens from the measurement of the intermetallic thickness with aging temperature and time.