• Advances in materials Research
• /
• v.13 no.1
• /
• pp.55-62
• /
• 2024

Cu-based sulfides have recently emerged as promising thermoelectric (TE) materials due to their low cost, non-toxicity, and abundance. In this research, point defect structure of Cu_2-xZnSnS₄ (x=0.1, 0.2, 0.3) samples were synthesized by the mechanical alloying method. Mixed powders of Cu, Zn, Sn and S were milled using high energy ball milling at a rotation speed of 300 rpm in Ar atmosphere. The milled Cu_2-xZnSnS₄ powders were heat-treated at 723 K for 24 h, and subsequently consolidated using spark plasma sintering (SPS) under an applied pressure of 60 MPa for 15 min. The thermal conductivity of the sintered Cu_2-xZnSnS₄ samples was evaluated. A well-defined Cu_2-xZnSnS₄ powders were successfully formed after milling for 16 h, with the particle sizes mostly distributed in the range of 60-100 nm. The lattice constants of aand cdecreased with increasing composition value x. The thermal conductivity of sintered x=0.1 sample exhibited the lowest value and attained 0.93 W/m K at 673 K.

• Food Science and Preservation
• /
• v.22 no.3
• /
• pp.345-352
• /
• 2015

This study was monitored the quality characteristic of the hyssop-rice drink added using hyssop (Hyssopus officinalis) and rice. AFter operational parameters including amylase content ($X_1$, 1~5 mL), saccharification time ($X_2$, 10~18 hr) and hyssop content ($X_3$, 1.0~3.0 g) were monitored, these results were analyzed using a response surface methodology for the determination of the optimum conditions (Brix, Hunter's color and organoleptic properties). Maximum conditions of Brix for the hyssop-rice drink were 0.96 mL of amylase, 14.93 hr of saccharification time and 2 g of hyssop. Maximum conditions of Hunter's color b were 1.90 mL of amylase, 16.64 hr of saccharification time and 2.51 g of hyssop. Maximum conditions of organoleptic color were 4.60 mL of amylase, 15.66 hr of saccharification time and 1.57 g of hyssop. Maximum conditions of organoleptic aroma were 3.46 mL of amylase, 10.79 hr of saccharification time and 1.45 g of hyssop. Maximum conditions of organoleptic taste were 3.67 mL of amylase, 17.64 hr of saccharification time and 1.76 g of hyssop. Maximum conditions of overall palatability of the hyssop-rice drink were 3.73 mL of amylase, 13.66 hr of saccharification time and 1.85 g of hyssop.

• Korean Journal of Materials Research
• /
• v.13 no.1
• /
• pp.48-52
• /
• 2003

The substituted yttrium iron garnet systems $Y_{ 3-x}$/Gd$_{x}$X$0.2_{0.2}$ $Fe_{4.8}$ $O _{12}$ (x = 0.2, 0.4, 0.6) have been investigated by means of X-ray diffraction, Mossbauer spectroscopy and SQUID. The X-ray diffraction patterns at room temperature confirm the samples to have a single phase of the garnet structure over the whole composition range. The lattice constants of all the samples linearly change with increasing x due to the size of substituted ions in the dodecahedral sites. $Y_{3-x}$ $Gd_{x}$ X$Fe_{4.8}$ $In_{0.2}$ $O_{12}$ system which $Y_{3-x}$ ions are substituted with Gd$^{ 3＋}$ ions, the Mossbauer spectrum consists of three Zeeman sextets at room temperature, one due to the $Fe^{3＋}$ ions on the octahedral(a-) sites and the others due to the $Fe^{3＋}$ ions on the tetrahedral(d-, d'-) sites, respectively. From the hysteresis loop measured by means of SQUID over the whole composition range, the saturation magnetization $M_{s}$ and magnetic moments $\mu_{ B}$ per unit cell have been obtained. The increment of Gd-ion content causes $M_{s}$ and $\mu_{B}$ decrease while the increment of In-ion content does not.

• Microbiology and Biotechnology Letters
• /
• v.17 no.2
• /
• pp.88-93
• /
• 1989

To improve a new yeast strain capable of converting xylan to ethanol directly, we tried protoplast fusion between xylose fermenting yeast (Candida sp. X-6-41) and xylan assimilating yeast (Crypto-coccus sp. XB-33), finally selected the most promising two fusants (XFU-1 and XFU-2). As the optimum conditions for protoplast formation, the yeast cells were cultured to exponential phase in YPD and YPX containing 0.6M KCI, respectively, and then treated with zymolyase (0.25mg/$m\ell$), cellulase(4mg/$m\ell$) and 100mM 2-mercaptoethanol at pH 8 and 3$0^{\circ}C$. The protoplasts of parental auxotrophs were fused in the presence of 20mM CaCl$_2$and 40% polyethylene glycol(M.W.4000). The physiological and morphological characteristics of the fusants, such as assimilation of carbon sources, cell size, growth rate, xylanase activity and xylan fermentation ability were investigated. Xylanase activity of fusants that cultured in chemically minimal medium was higher than that of fusants that cultured in completed medium, because xylanase producing activity of xylose fermenting yeast(X-6-41) was inhibited by isoleucine.

• IMMUNE NETWORK
• /
• v.15 no.1
• /
• pp.44-49
• /
• 2015

Interactions between microbes and epithelial cells in the gastrointestinal tract are closely associated with regulation of intestinal mucosal immune responses. Recent studies have highlighted the modulation of mucosal immunity by microbe-derived molecules such as ATP and short-chain fatty acids. In this study, we undertook to characterize the expression of the ATP-gated $P2X_7$ receptor ($P2X_7R$) on M cells and its role in gastrointestinal mucosal immune regulation because it was poorly characterized in Peyer's patches, although purinergic signaling via $P2X_7R$ and luminal ATP have been considered to play an important role in the gastrointestinal tract. Here, we present the first report on the expression of $P2X_7R$ on M cells and characterize the role of $P2X_7R$ in immune enhancement by ATP or LL-37.

• Kyungpook Mathematical Journal
• /
• v.19 no.2
• /
• pp.237-239
• /
• 1979

No matter how one chooses the major arcs in the decomposition of $[x_0,\;x_0+1]$ it is always true with regard to the union, m(n), of the corresponding minor arcs that the integal of $f^2(x,\;n)$ e(-nx) over m(n) is $O(nlog^{-1}n)$. Consequently, to establish a proof of the asymptotic formulation of Goldbach's conjecture one might be tempted to take this fact as a starting point and to then concentrate the attact on trying to obtain the requisite estimate on the integral of $f^2(x,\;n)$ e(-nx) over M(n), the union of a suitably chosen family of major arcs. In this paper I show that this approach is not possible.

• Journal of the Korean Magnetics Society
• /
• v.18 no.2
• /
• pp.75-78
• /
• 2008

$AB_2X_4$(A, B=Transition Metal, X=O, S, Se) are cubic spinel normal ferrimagnets, in which M ions occupy the tetrahedral sites and Cr ions occupy the octahedral sites. Recently, they have been investigated for behaviour of B site ions and A-B interaction. Polycrystalline $[Co_{0.9}Zn_{0.1}]_A[Cr_{1.98}{^{57}Fe_{0.02}}]_BO_4$ compound was prepared by wet-chemical process. The ferrimagnetic transition was observed around 90K. $M\"{o}ssbauer$ absorption spectra at 4.2K show that the well-developed two sextets are superposed with small difference in hyperfine fields($H_{hf}$). The hyperfine fields of $CoCr_{1.98}{^{57}Fe_{0.02}}O_4$ and $Co_{0.9}Zn_{0.1}Cr_{1.98}{^{57}Fe_{0.02}}O_4$ were determined to be 488, 478 kOe and 486, 468 kOe, respectively. We notice that the one of the magnetic hyperfine field values changes with Zn ion substitution. These results suggest the incommensurate states and spin-reorientation temperature($T_S=18K$) changes with Zn ions substitution below spin-reorientation temperature($T_S=28K$) of $CoCr_{1.98}{^{57}Fe_{0.02}}O_4$

• Proceedings of the Korean Magnestics Society Conference
• /
• 2005.12a
• /
• pp.172-172
• /
• 2005

• Korean Journal of Food Science and Technology
• /
• v.30 no.2
• /
• pp.341-347
• /
• 1998

To develop simple and accurate analytical method for freezing time prediction of beef and tylose under various freezing conditions, freezing time (Y) was regressed against the reciprocal $(X_3)$ of difference of initial freezing point and freezing medium temperature, reciprocal $(X_4)$ of surface heat transfer coefficient, the initial temperature $(X_1)$ and thickness $(X_2)$ of samples which should cover most situations arising in frozen food industry. As results of the multiple regression analysis, equations were obtained as follows. $Y_{tylose}=3.45X_1+7642.84X_2+4642.67X_3+2946.89X_4-431.33\;(R^2=0.9568)$ and $Y_{beef}=0.68X_1+7568.98X_2+2430.78X_3+3293.26X_4-299.00\;(R^2=0.9897)$. These equations offered better results than Plank, Nagaoka and Pham's models, shown in satisfactory agreement with models of Cleland & Earle and Hung & Thompson when were compared to previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results. Also, thermal diffusivities of beef and tylose were measured as $4.43{\times}10^{-4}m^2/hr$ and $4.39{\times}10^{-4}m^2/hr$ at $6{\sim}7^{\circ}C$, $2.42{\times}10^{-3}m^2/hr$ and $3.32{\times}10^{-3}m^2/hr$ at $-10{\sim}-12^{\circ}C$. Initial freezing points of beef and tylose were $-1.2^{\circ}C\;and\;-0.6^{\circ}C$, respectively. Surface heat transfer coefficients were estimated $20.57\;W/m^2^{\circ}C$ with no-packing, $16.11\;W/m^2^{\circ}C$ with wrap packing and $13.07\;W/m^2^{\circ}C$ with Al-foil packing, and the cooling rate of immersion freezing method was about 10 times faster than that of air blast freezing method.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.1
• /
• pp.65-68
• /
• 1999

Novel mononuclear group 13 metal complexes with the formula (R2M){NC5H4C(CH3)NNC(S)NH(C6H5)} (M=Al, R=iC4H9 (1); M=Ga, R=iC4H9 (2); M=Al, R=CH2SiMe3 (3); M=Ga, R=CH2SiMe3 (4)) result when 2-acetyl pyridine 4-phenyl-thiosemicarbazone ligand is mixed with trialkyl aluminum or trialkylgallium. These compounds 1-4 are characterized by microanalysis, NMR (1H, 13C) spectroscopy, mass spectra, and singlecrystal X-ray diffraction. X-ray single-crystal diffraction analysis reveals that 1 is mononuclear metal compound with coordination number of 5 and N, N, S-coordination mode.