• Title/Summary/Keyword: ($(Gd\

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Spark plasma sintering of UO2 fuel composite with Gd2O3 integral fuel burnable absorber

  • Papynov, E.K.;Shichalin, O.O.;Belov, A.A.;Portnyagin, A.S.;Buravlev, I.Yu;Mayorov, V.Yu;Sukhorada, A.E.;Gridasova, E.A.;Nomerovskiy, A.D.;Glavinskaya, V.O.;Tananaev, I.G.;Sergienko, V.I.
    • Nuclear Engineering and Technology
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    • v.52 no.8
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    • pp.1756-1763
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    • 2020
  • The paper studies spark plasma sintering (SPS) of industrially used UO2-based fuel containing integral fuel burnable absorber (IFBA) of neutrons Gd2O3. Densification dynamics of pristine UO2 powder and the one added with 2 and 8 wt% of Gd2O3 under ultrasonication in liquid has been studied under SPS conditions at 1050, 1250, and 1450 ℃. Effect of sintering temperature on phase composition as well as on O/U stoichiometry has been investigated for UO2 SPS ceramics. Sintering of uranium dioxide added with Gd2O3 yields solid solution (U,Gd)O2, which is isostructural to UO2. SEM with EDX and metallography were implemented to analyze the microstructure of the obtained UO2 ceramics and composite UO2-Gd2O3 one, particularly, open porosity, defects, and Gd2O3 distribution were studied. Microhardness, compressive strength and density were shown to reduce after addition of Gd2O3. Obtained results prove the hypothesis on formation of stable pores in the system of UO2-Gd2O3 due to Kirkendall effect that reduces sintering efficiency. The paper expands fundamental knowledge on pros and cons of fuel fabrication with IFBA using SPS technology.

Effects of Al Doping on Sinterabllity and Microstructure in $UO_2-6wt%Gd_2O_3$ Pellets ($UO_2-6wt%Gd_2O_3$ 소결체에서 Al 첨가가 소결성 및 미세조직에 미치는 영향)

  • Baek, Jong-Hyeok;Yu, Ho-Sik;Yun, Gyeong-Ho;Kim, Hyeong-Su;Seo, Geum-Seok
    • Korean Journal of Materials Research
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    • v.5 no.6
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    • pp.644-649
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    • 1995
  • The sinterability and the microstructure of Al doped UO$_2$-6wt%Gd$_2$O$_3$pellets, which were doped using Al(OH)$_3$, ADS(aluminium distearate), Al(OH)$_3$+ ADS mixture and sintered at 1$700^{\circ}C$ for 4h in H$_2$, atmospheres, were examined. The sintered densities of Al doped UO$_2$-6wt%Gd$_2$O$_3$pellets were more than 94% T.D.. The open porosity in ADS doped pellets was dramatically decreased. And the amounts of pores less than l${\mu}{\textrm}{m}$ and larger than 10${\mu}{\textrm}{m}$ were decreased regardless of the kinds of doped Al compounds. And the average pore size of Al doped UO$_2$-6wt%Gd$_2$O$_3$pellets was ranged between 2 and 3${\mu}{\textrm}{m}$. While grain structure of non-doped UO$_2$-6wt%Gd$_2$O$_3$pellets was revealed to be duplex type (rocks in sands), that of Al doped pellets to be uniformly equiaxid type. Especially, the grain size in ADS doped pellets was averaged to 4.6${\mu}{\textrm}{m}$.

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Ganglioside GD1a Activates the Phosphorylation of EGFR in Porcine Oocytes Maturation in vitro

  • Park, Hyo-Jin;Kim, Jin-Woo;Park, Jae-Young;Yang, Seul-Gi;Jung, Jae-Min;Kim, Min-Ji;Koo, Deog-Bon
    • Journal of Embryo Transfer
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    • v.32 no.1
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    • pp.17-24
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    • 2017
  • Ganglioside GD1a is specifically formed by the addition of sialic acid to ganglioside GM1a by ST3 ${\beta}$-galactoside ${\alpha}$-2,3-sialyltransferase 2 (ST3GAL2). Above all, GD1a are known to be related with the functional regulation of several growth factor receptors, including activation and dimerization of epidermal growth factor receptor (EGFR) in tumor cells. The activity of EGF and EGFR is known to be a very important factor for meiotic and cytoplasmic maturation during in vitro maturation (IVM) of mammalian oocytes. However, the role of gangliosides GD1a for EGFR-related signaling pathways in porcine oocyte is not yet clearly understood. Here, we investigated that the effect of ST3GAL2 as synthesizing enzyme GD1a for EGFR activation and phosphorylation during meiotic maturation. To investigate the expression of ST3GAL2 according to the EGF treatment (0, 10 and 50 ng/ml), we observed the patterns of ST3GAL2 genes expression by immunofluorescence staining in denuded oocyte (DO) and cumulus cell-oocyte-complex (COC) during IVM process (22 and 44 h), respectively. Expression levels of ST3GAL2 significantly decreased (p<0.01) in an EGF concentration (10 and 50 ng/ml) dependent manner. And fluorescence expression of ST3GAL2 increased (p<0.01) in the matured COCs for 44 h. Under high EGF concentration (50 ng/ml), ST3GAL2 protein levels was decreased (p<0.01), and their shown opposite expression pattern of phosphorylation-EGFR in COCs of 44 h. Phosphorylation of EGFR significantly increased (p<0.01) in matured COCs treated with GD1a for 44 h. In addition, ST3GAL2 protein levels significantly decreased (p<0.01) in GD1a ($10{\mu}M$) treated COCs without reference to EGF pre-treatment. These results suggest that treatment of exogenous ganglioside GD1a may play an important role such as EGF in EGFR-related activation and phosphorylation in porcine oocyte maturation of in vitro.

Comparisons of the prevalence and analysis of risk factors affecting gallstone disease on Jeju Island

  • Kwon, Oh-Sung;Kim, Young-Kyu
    • Journal of the Korea Society of Computer and Information
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    • v.27 no.3
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    • pp.119-126
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    • 2022
  • The reported risk factors for gallstone disease (GD) are old age, female sex, obesity, metabolic syndrome and migrants. Many younger adults tend to live in Jeju City, where transportations are convenient and commercial activities are active. Whereas, older people tend to live in Seogwipo City, because they engaged in fisheries and agriculture. Rates of migrants and old age could affect the prevalence of GD among residents in two regions. Therefore, the purpose of this study was to compare the GD prevalence and analyze risk factors affecting GD including residencies. A total of 13,050 subjects who visited a single health medical check-up center on Jeju Island between 2012 and 2019 were included. We performed univariate and multivariate analysis to identify risk factors for GD. The prevalence of GD among residents were 5.7% in Jeju City and 5.8% in Seogwipo City, respectively. Multivariate analysis revealed that age (P=0.008), body mass index (P=0.044), high-density lipoprotein cholesterol (P=0.006) and gamma-glutamyl transferase (P=0.013) were independent factors affecting GD. The old age, mean higher body mass index, gamma-glutamyl transferase and mean lower high-density lipoprotein cholesterol were independent risk factors affecting GD. However, residencies did not affect the prevalence of GD.

Phase Transition Temperature Shift of a Ferromagenetic Gadelonium Film due to the Finite-Size Effects (Finite-Size Errect에 의한 강바성 Gd박막의 상전이온도 이동)

  • Rhee, Il-Su;Lee, Eui-Wan;Lee, Sang-Yun
    • Korean Journal of Materials Research
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    • v.3 no.1
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    • pp.3-6
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    • 1993
  • Abstract We report the result of measurement for the ferro-to paramagnetic phase transition temperature shift of a gadolinium film. The phase transition temperature has been determined by measuring the resistance changes of film as function of temperature. At the ferro-to paramagnetic transition temperature, we can observe the inflection point of resistance changes. The phase transition temperature of 6600$\AA$ gadolinium film is found to be shifted by 4 $\pm$ 0.$3^{\circ}C$ below the transition temperature of bulk gadolinium. This is the first measurement for the phase transition temperature shift of ferromagnetic gadolinium film. This and further results might give a milestone in resolving the differences between experiments and finite-size scaling theory.

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Effects of High-Pressure, Microbial Transglutaminase and Glucono-δ-Lactone on the Aggregation Properties of Skim Milk

  • Lee, Sang Yoon;Choi, Mi-Jung;Cho, Hyung-Yong;Davaatseren, Munkhtugs
    • Food Science of Animal Resources
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    • v.36 no.3
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    • pp.335-342
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    • 2016
  • The object in this study is to investigate the effects of high pressure and freezing processes on the curdling of skim milk depending on the presence of transglutaminase (TGase) and glucono-δ-lactone (GdL). Skim milk was treated with atmospheric freezing (AF), high pressure (HP), pressure-shift freezing (PSF) and high pressure sub-zero temperature (HPST) processing conditions. After freezing and pressure processing, these processed milk samples were treated with curdling agents, such as TGase and GdL. Pressurized samples (HP, PSF and HPST) had lower lightness than that of the control. In particular, PSF had the lowest lightness (p<0.05). Likewise, the PSF proteins were the most insoluble regardless of whether they were activated by TGase and GdL, indicating the highest rate of protein aggregation (p<0.05). Furthermore, the TGase/GdL reaction resulted in thick bands corresponding to masses larger than 69 kDa, indicating curdling. Casein bands were the weakest in PSF-treated milk, revealing that casein was prone to protein aggregation. PSF also had the highest G' value among all treatments after activation by TGase, implying that PSF formed the hardest curd. However, adding GdL decreased the G' values of the samples except HPST-treated samples. Synthetically, the PSF process was advantageous for curdling of skim milk.

Gd-Complexes of DTPA-bis(amides) Functionalized by Pyridine and Picolinamide: Synthesis, Thermodynamic Stability, and Relaxivity Properties

  • Sk, Nasiruzzaman;Park, Ji-Ae;Chang, Yong-Min;Kim, Tae-Jeong
    • Bulletin of the Korean Chemical Society
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    • v.29 no.6
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    • pp.1211-1216
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    • 2008
  • A series of DTPA-bis(amides) functionalized by pyridine (1a-c) and N-phenylpicolinamide) (1d-e) and their Gd(III)-complexes of the type [Gd(1)($H_2O$)]·x$H_2O$ (2a-e) were prepared and characterized by analytical and spectroscopic techniques. Potentiality of 2a-e as contrast agents for magnetic resonance imaging (MRI CA) was investigated by measuring relevant physicochemical properties and relaxivities and compared with [Gd(DTPA-BMA)($H_2O$)] (DTPA-BMA=N,N''-di(methylcarbamoylmethyl)diethylenetriamine-N,N',N''-triacetate) ($Omniscan^{(R)}$). The R1 relaxivities of aqueous solutions of 2a-c are in the range of 3.33 -5.02 $mM^{-1}$$sec^{-1}$, which are comparable with those of $Omniscan^{(R)}$ (r1=4.58 $mM^{-1}sec^{-1}$). Complexes 2d-e, insoluble in water, exhibit relatively higher R1 values (8.1- 8.3 $mM^{-1}sec^{-1}$) in HP-$\beta$-CD solutions.

Microwave Sintering of Gd-Doped CeO2 Powder (Gd-Doped CeO2 분말의 마이크로파 소결)

  • Kim, Young-Goun;Kim, Seuk-Buom
    • Journal of the Korean Ceramic Society
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    • v.44 no.3 s.298
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    • pp.182-187
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    • 2007
  • 10 mol% $Gd_{2}O_{3}-CeO_{2}$ powder was sintered by microwave in a 2.45 GHz multimode cavity to develop a dense electrolyte layer for intermediate temperature solid oxide fuel cells (IT-SOFCs). Samples were sintered from $1100^{\circ}C$ upto $1500^{\circ}C$ by $50^{\circ}C$ difference and kept for 10 min and 30 min at the maximum temperature respectively. Theoretical density of the sample sintered at $1200^{\circ}C$ for 10 min was 95.4% and increased gradually upto 99% in the sample sintered at $1500^{\circ}C$ for 30 min. All of sintered samples showed very fine microstructures and the maximum average grain size of the sintered sample at $1500^{\circ}C$ for 30 min was $(0.87{\pm}0.42){\mu}m$. Ionic conductvity of the samples were measured by DC 4 probe method.

Photoluminescence properties of $Gd_{1-x}Ln_xCa_3(GaO)_3(BO_3)_4$ (Ln=Eu, Tb, Tm) under UV excitation

  • Kyung, Hyun-Ai;Jung, Ha-Kyun;Seong, Tae-Yeon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1565-1568
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    • 2007
  • A borate compound was adopted as new host material for $Eu^{3+}$, $Tb^{3+}$ and $Tm^{3+}$ activators. The phosphor samples, $Gd_{1-x}Eu_xCa_3(GaO)_3(BO_3)_4$, $Gd_{1-x}Tb_xCa_3(GaO)_3(BO3)_4$ and $Gd_{1-x}Tm_xCa_3(GaO)_3(BO_3)_4$ have been synthesized by conventional solid-state reaction. The crystalline phase for the resulting powders was identified using an X-ray diffraction $system^1$. Their photoluminescence properties under the excitation of UV ray were investigated. The Eu, Tb or Tm-doped $GdCa_3(GaO)_3(BO_3)_4$ emits efficient red, green or blue light, respectively. It was observed that the optimum concentration of Eu or Tb activator for the borate host was much higher than other $Eu^{3+}$ or $Tb^{3+}-doped$ phosphors.

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A Study on the Magnetic Properties of Amorphous Fe-Co-RE-B (RE=Nd, Sm, Gd, Tb) Alloys (비정질 Fe-Co-Re-B(RE=Nd, Sm, Gd, Tb) 합금의 자기적 성질)

  • 김경섭;유성초;김창식;김종오
    • Journal of the Korean Magnetics Society
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    • v.1 no.2
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    • pp.55-59
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    • 1991
  • The temperature-dependent magnetization curves of amorphous Fe-Co-(Nd, Sm, Gd, Tb)-B alloys were measured using a vibrating sample magnetometer from 77 K up to 900 K. The spin wave stiffness constants and the range of the exchange interaction were calculated from the saturation magnetization values at 0 K. Curie temperatures and the Bloch coefficients estimated from the saturation magnetization curves. The low temperature dependence of magnetization is in good agreement with Bloch relation, $M_{s}(T)=M_{s}(O)(1-BT^{3/2}-CT^{5/2})$. The spin wave stiffness constant and the range of exchange interaction are decreased by substitution of heavy rare earth (Tb, Gd).

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