• Title/Summary/Keyword: Borate

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Ionic Conductivity in Lithium-Borate-Tantalate Compound Glasses

  • Kwon, Oh Hyeok;Yang, Yong Suk;Rim, Young Hoon
    • Journal of the Korean Physical Society
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    • v.73 no.12
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    • pp.1873-1878
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    • 2018
  • We have investigated the ionic conductivity and dielectric relaxation in $Li_2B_4O_7$ (LBO) and $Li_2O-B_2O_3-Ta_2O_5$ (LBTO) glasses. The sample was synthesized by using the melt quenching method. The frequency dependence of the electrical data from the LBO and LBTO glasses has been analyzed in the frameworks of the impedance Cole-Cole formalism and the universal power-law representation driven by the modified fractional Rayleigh equation. The potential barriers in the LBO and the LBTO glasses turn out to be the same. Comparing with the dc and ac activation energies of the LBO glass, these energies of the LBTO glass decrease due to the increasing Coulomb interaction of inter-cationic interaction.

Mechanical and elastic properties of vitrified radioactive wastes using ultrasonic technique

  • Sema Akyil Erenturk;Filiz Gur;Mahmoud A.A. Aslani
    • Nuclear Engineering and Technology
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    • v.56 no.2
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    • pp.472-476
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    • 2024
  • It is important that radioactive and nuclear wastes are immobilized in a glass composition with lower melting temperatures due to their economy. In this study, the elastic and mechanical properties of sodium borate-based vitrified radioactive waste were measured using ultrasonic techniques. Many ultrasonic parameters, such as elastic moduli, Poisson's ratio, and microhardness, were calculated by measuring the ultrasonic velocities of the glasses. The ultrasonic velocity data, the density, the calculated elastic moduli, micro-hardness, softening temperature, and Debye temperature depending on the glass composition were evaluated, and the relation with the structure was clarified. It was observed that the elastic modulus and Poisson ratio increased as the Cs2O content increased in glasses containing Cs waste. This result shows that the rigidity of the network structure of these glasses increases in contrast to the glass containing Sr.

Predicting In Sacco Rumen Degradation Kinetics of Raw and Dry Roasted Faba Beans (Vicia faba) and Lupin Seeds (Lupinus albus) by Laboratory Techniques

  • Yu, P.;Egan, A.R.;Leury, B.J.
    • Asian-Australasian Journal of Animal Sciences
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    • v.13 no.10
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    • pp.1377-1387
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    • 2000
  • Two laboratory techniques: (1) an in vitro method with two procedures for measuring protein degradabilities and (2) an in vitro method with three procedures for measuring protein solubility, were investigated to determine which laboratory techniques could most accurately predict the quantity of rumen protein degradation kinetics of legume seeds after dry roasting under various conditions, in terms of (1) rumen protein disappearance ($D_j$, where j=0, 2, 4, 8, 12, 24 and 48 h incubation), (2) rumen protein effective degradability (EDCP), (3) the parameters describing rumen degradation characteristics (the soluble fraction: S, the potentially degradable fraction: D, undegradable fraction: U, lag time: T0 and the degradation rate: Kd) and (4) rumen bypass protein (BCP), which were determined by the method accepted internationally at present, in sacco nylon bag technique using the standardized Dutch method. Feeds evaluated were the raw and dry roasted whole faba (Vicia faba) beans (WFB) and whole lupin (Lupinus albus) seeds (WLS), each was dry roasted under various conditions (at 110, 130 or $150^{\circ}C$ for 15, 30 or 45 min). In vitro protein degradability ($D_1$_Auf and $D_{24}$_Auf) were determined using the modified Aufr re method by enzymatic hydrolysis for 1 h and 24 h using a protease extracted from Streptomyces griseus in a borate-phosphate buffer. In vitro protein solubility ($bf_1$_S, $bf_2$_S, $bf_3$_S) was measured in a borate-phosphate buffer with three different procedures. Results from laboratory techniques (in vitro) were correlated and linearly regressed with in sacco results. Of the three procedures of in vitro protein solubility evaluated, none of them could predict in sacco results with good precision. The highest Pearson correlation coefficient ($R^2$) was less than 0.50. Of two procedures of in vitro protein degradability studied, the $D_1$_Auf values were closely correlated with in sacco parameters: Kd, EDCP and %BCP with high R' values: 0.82, 0.85 and 0.85, respectively, and closely correlated with in sacco $D_j$ at 2, 4, 8 and 12 h rumen incubation with high $R^2$ values: 0.83, 0.91, 0.93 and 0.83, respectively. The $D_{24}$_Auf values could not predict in sacco results. The highest $R^2$ value was less then 0.40. These results indicated that in vitro protein solubility measured in borate-phosphate failed to identify differences in the rate and extent of protein degradation of legume seeds after dry roasting under various conditions and thus should not be used to predict rumen degradation, particularly for heat processed feedstuffs. But in vitro protein degradability using the modified Aufr re method by enzymatic hydrolysis for 1 h or possibly an intermediate time (>1 h and <24 h) is a promising laboratory procedure to detect effectiveness of dry roasting legume seeds on rumen protein degradation characteristics and could be used as a simple laboratory method to predict the rate and extent of protein degradation in the rumen in sacco with high accuracy. The equations to predict EDCP, Kd and BCP of dry roasted legume seeds (WLS and WFB) under various conditions are as follow: For both: EDCP (%)=-1.37+1.06*$D_1$_Auf ($R^2=0.85$, p<0.01). For both: Kd (%/h)=-21.81+0.49*$D_1$_Auf ($R^2=0.82$, p<0.01). For both: %BCP=103.37-1.07*$D_1$_Auf ($R^2=0.85$, p<0.01).

Effect of Boron Content on Atomic Structure of Boron-bearing Multicomponent Oxide Glasses: A View from Solid-state NMR (비정질 소듐 보레이트와 붕소를 함유한 다성분계 규산염 용융체의 붕소의 함량에 따른 원자 구조에 대한 고상 핵자기 공명 분광분석 연구)

  • Lee, A Chim;Lee, Sung Keun
    • Journal of the Mineralogical Society of Korea
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    • v.29 no.3
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    • pp.155-165
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    • 2016
  • Understanding the effect of boron content on atomic structures of boron-bearing multicomponent silicate melts is essential to reveal the atomistic origins of diverse geochemical processes involving silica-rich magmas, such as explosive volcanic eruption. The detailed atomic environments around B and Al in boron-bearing complex aluminosilicate glasses yield atomistic insights into reactivity of nuclear waste glasses in contact with aqueous solutions. We report experimental results on the effect of boron content on the atomic structures of sodium borate glasses and boron-bearing multicomponent silicate melts [malinkoite ($NaBSiO_4$)-nepheline ($NaAlSiO_4$) pseudo-binary glasses] using the high-resolution solid-state NMR ($^{11}B$ and $^{27}Al$). The $^{11}B$ MAS NMR spectra of sodium borate glasses show that three-coodrinated boron ($^{[3]}B$) increases with increasing $B_2O_3$ content. While the spectra imply that the fraction of non-ring species decreases with decreasing boron content, peak position of the species is expected to vary with Na content. Therefore, the quantitative estimation of the fractions of the ring/non-ring species remains to be explored. The $^{11}B$ MAS NMR spectra of the glasses in the malinkoite-nepheline join show that four-coordinated boron ($^{[4]}B$) increases as $X_{Ma}$ [$=NaBSiO_4/(NaBSiO_4+NaAlSiO_4)$] increases while $^{[3]}B$ decreases. $^{27}Al$ MAS NMR spectra of the multicomponent glasses confirm that four-coordinated aluminum ($^{[4]}Al$) is dominant. It is also observed that a drastic decrease in the peak widths (full-width at half-maximum, FWHM) of $^{[4]}Al$ with an addition of boron ($X_{Ma}=0.25$) in nepheline glasses. This indicates a decrease in structural and topological disorder around $^{[4]}Al$ in the glasses with increasing boron content. The quantitative atomic environments around boron of both binary and multicomponent glasses were estimated from the simulation results of $^{11}B$ MAS NMR spectra, revealing complex-nonlinear variation of boron topology with varying composition. The current results can be potentially used to account for the structural origins of the change in macroscopic properties of boron-bearing oxide melts with varying boron content.

A Fundamental Study of Eu2+ Luminescence in Aluminum Borate Compounds (Aluminum Borate 화합물에 있어서 EU2+이온의 발광성)

  • Chang, Ki-Seog
    • Journal of the Korean Chemical Society
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    • v.44 no.4
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    • pp.350-355
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    • 2000
  • The compounds, CaAl$_2$(BO$_3$)$_2$O, SrAl$_2$(BO$_3$)$_2$O and BaAl$_2$(BO$_3$)$_2$O, are good host lattices for highly efficient $Eu^{2+}$ luminescence. The europium emission peaks at 450 nm in $Eu^{2+}$:CaAl$_2$(B0$_3$)$_2$O, 411 nm in $Eu^{2+}$: SrAl$_2$(BO$_3$)$_2$O and 375 nm in $Eu^{2+}$: BaAl$_2$(BO$_3$)$_2$O. The $Eu^{2+}$: CaAl$_2$(BO$_3$)$_2$O Phosphor shows a high output and should be a good maintenance in VUV Xe lamps. It is ideally suited for use in PDP phosphors. The $Eu^{2+}$ ion is interesting because the Stokes shift emission is a strong host dependent. The difference in the Stokes shift is oneimportant factor leadingto a difference in wavelength. If the 5d level of $Eu^{2+}$ ion is lower in energy,according to a decrease in the doping lattice size, then the emission wavelength will be longer and the Stokes shift will be smaller. Therefore, a knowledge of the relationship between the crystal lattice size and the Stokes shift. (orthe energy of the 5d level),is essential for beingable to predict $Eu^{2+}$ emission properties.

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Effect of Sphingosine-1-Phosphate on Intracellular Free Ca2+ in Cat Esophageal Smooth Muscle Cells

  • Lee, Dong Kyu;Min, Young Sil;Yoo, Seong Su;Shim, Hyun Sub;Park, Sun Young;Sohn, Uy Dong
    • Biomolecules & Therapeutics
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    • v.26 no.6
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    • pp.546-552
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    • 2018
  • A comprehensive collection of proteins senses local changes in intracellular $Ca^{2+}$ concentrations ($[Ca^{2+}]_i$) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular $Ca^{2+}$ concentrations in cat esophageal smooth muscle cells. To measure $[Ca^{2+}]_i$ levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in $[Ca^{2+}]_i$ in the cells. Pretreatment with EGTA, an extracellular $Ca^{2+}$ chelator, decreased the S1P-induced increase in $[Ca^{2+}]_i$, and an L-type $Ca^{2+}$-channel blocker, nimodipine, decreased the effect of S1P. This indicates that $Ca^{2+}$ influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an $InsP_3$ receptor blocker, the S1P-evoked increase in $[Ca^{2+}]_i$ was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of $G_i$-protein, suppressed the increase in $[Ca^{2+}]_i$ evoked by S1P. These results suggest that the S1P-induced increase in $[Ca^{2+}]_i$ in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of $Ca^{2+}$ from the $InsP_3$-sensitive $Ca^{2+}$ pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular $Ca^{2+}$ via the L type $Ca^{2+}$ channel, which was dependent on activation of the $S1P_4$ receptor coupled to PTX-sensitive $G_i$ protein, via phospholipase C-mediated $Ca^{2+}$ release from the $InsP_3$-sensitive $Ca^{2+}$ pool in cat esophageal smooth muscle cells.

Studies on Preparation of Boron Compounds from Colemanite Ore : Preparation of Boric Acid and Reaction Mechanism (I) (Colemanite 광물로부터 붕소화합물의 제조에 관한 연구 : 붕산제조 및 반응기구 (I))

  • Choi, Byung-Hyun;Lim, Hyung-Mi;Jee, Mi-Jung;Jang, Jae-Hun;Paik, Song-Hoo;Lee, Mi-Jai
    • Journal of the Korean Ceramic Society
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    • v.41 no.10 s.269
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    • pp.756-765
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    • 2004
  • We present extraction process and reaction mechanism of boric acid from one of calcium borate ores, colemanite by reaction with sulfuric acid. Colemanite has been fully decomposed under pH 5 with sufficiency amount of sulfuric acid, more than the amount stoichiometrically required. Calcium sulfate was separated out, leaving boron in the liquid phase after sulfuric acid addition. The extraction process of boric acid was affected by dissolution temperature and time, amount of sulfuric acid and ammonium sulfate, pH and a degree of concentration before recrystallization. The $SiO_2$ of the impurities which colemanite contains was insoluble so that it was separated out with calcium sulfate from liquid phase. The species of $CaO,\;Al_2O_3,\;Fe_2O_3,\;MgO$ were remained in a liquid phase after reaction with sulfuric acid. These impurities were separated out by addition of ammonia to the liquid phase, funhermore, boric acid was produced by process of pH adjustments and acidification, concentration, and recrystallization.

Immobilization of Late Transition Metal Catalyst on the Amino-functionalized Silica and Its Norbornene Polymerization (아미노-기능화된 실리카 위 후전이 금속 촉매 담지 및 이를 이용한 노보넨 중합)

  • Pacia, Rose Mardie P.;Kim, So Hui;Lee, Jeong Suk;Ko, Young Soo
    • Applied Chemistry for Engineering
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    • v.27 no.3
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    • pp.313-318
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    • 2016
  • In this study, an amorphous silica was functionalized with aminosilane, N-[(3-trimethoxysilyl)propyl]ethylenediamine (2NS) and the late transition metal catalysts including ($(DME)NiBr_2$ and $PdCl_2$(COD)) were subsequently immobilized on the functionalized amorphous silica for norbornene polymerization. Effects of the polymerization temperature, polymerization time, Al/Ni molar ratio, and type of co-catalyst on norbornene polymerization were investigated. Unsupported late transition metal catalysts did not show any activities for norbornene polymerization. However, the $SiO_2$/2NS/Ni catayst with MAO system, with increasing polymerization temperature, increased the polymerization activity and decreased the molecular weight of the polynorbornene (PNB). Furthermore, the catalyst when increasing polymerization temperature caused the decrease in both the polymerization activity and molecular weight of PNB. This confirmed that the stability of $SiO_2$/2NS/Ni at a high temperature was greater than that of $SiO_2$/2NS/Pd. Also the longer polymerization time resulted in the higher conversion of norbornene for both catalysts. When the Al : Ni molar ratio was 1000 : 1, the highest activity (15.3 kg-PNB/($({\mu}mol-Ni^*hr$)) but lowest molecular weight ($M_n$ = 124,000 g/mol) of PNB were achieved. Also $SiO_2$/2NS/Ni catalyst with borate/TEAL resulted in diminishing the polymerization activity and molecular weight of PNB with increasing the polymerization temperature.

Studies on the Physico-chemical Properties of Vitrified Forms of the Low- and Intermediate-level Radioactive Waste (${\cdot}$저준위 방사성폐기물 유리고화체의 물리${\cdot}$화학적 특성 연구)

  • Kim, Cheon-Woo;Park, Byoung-Chul;Kim, Hyang-Mi;Kim, Tae-Wook;Choi, Kwan-Sik;Park, Jong-Kil;Shin, Sang-Woon;Song, Myung-Jae
    • Journal of the Korean Ceramic Society
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    • v.38 no.9
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    • pp.839-845
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    • 2001
  • In order to vitrify the Ion-Exchange Resin(IER), Dry Active Waste(DAW), and borate concentrate generated from the commercial nuclear facilities, the glass formulation study based on the their compositions was performed. Two glasses named as RG-1 and DG-1 were formulated as the candidate glasses for the vitrification of hte IER and DAW, respectively. A glass named as MG-1 was also formulated as a candidate glass for the vitrification of the mixed wastes containing the IER, DAW, and borate concentrate. The process parameters, product qualities, and economics were evaluated for the candidate glasses and confirmed experimentally for the some properties. The glass viscosity and electrical conductivity as the process parameters were in the desired ranges. the product qualities such as glass density, chemical durability, phase stability, etc. were satisfactory. In case of vitrifying the wastes using our developed glass formulation study, the volume reduction factors for the IER, DAW and mixed wastes were evaluated as 21, 89 and 75, respectively.

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Growth Behavior of Aluminum Borate Whisker under 2.45 GHz Electromagnetic Irradiation (2.45 GHz 전자기파 조사하에서 Aluminum Borate Whisker의 성장 거동)

  • 김성완;이상근;김지경;이창희;안진모;신준식;박성수;박희찬
    • Journal of the Korean Ceramic Society
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    • v.40 no.10
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    • pp.998-1004
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    • 2003
  • With starting materials of two different powder mixtures, $Al_2$(S $O_4$)$_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7) and ${\gamma}$-Al$_2$ $O_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7), whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were synthesized by using conventional and microwave heat-treatment. The effects of microwave, amount of flux and temperature on the growth of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were investigated by using X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). With increase of heat-treatment temperature and amount of flux, the size of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles increased in both conventional and microwave heat-treated samples. However, compared to the conventional heat-treated samples, whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were well grown for the microwave heat-treated samples.ted samples.