Lead-free perovskite ceramics, which have excellent energy storage capabilities, are attracting attention owing to their high power density and rapid charge-discharge speed. Given that the energy-storage properties of perovskite ceramic capacitors are significantly improved by doping with various elements, modifying their chemical compositions is a fundamental strategy. This study investigated the effect of Zn doping on the microstructure and energy storage performance of potassium sodium niobate (KNN)-based ceramics. Two types of powders and their corresponding ceramics with compositions of (1-x)(K,Na)NbO3-xBi(Ni2/3Ta1/3)O3 (KNN-BNT) and (1-x)(K,Na)NbO3-xBi(Ni1/3Zn1/3Ta1/3) O3 (KNN-BNZT) were prepared via solid-state reactions. The results indicate that Zn doping retards grain growth, resulting in smaller grain sizes in Zn-doped KNN-BNZT than in KNN-BNT ceramics. Moreover, the Zn-doped KNNBNZT ceramics exhibited superior energy storage density and efficiency across all x values. Notably, 0.9KNN-0.1BNZT ceramics demonstrate an energy storage density and efficiency of 0.24 J/cm3 and 96%, respectively. These ceramics also exhibited excellent temperature and frequency stability. This study provides valuable insights into the design of KNNbased ceramic capacitors with enhanced energy storage capabilities through doping strategies.

The grain growth behavior in the (1-x)K0.5Na0.5NbO3-xCaZrO3 (KNNCZ-x) system is studied as a function of the amount of CZ and grain shape. The (1-x)K0.5Na0.5NbO3-xCaZrO3 (KNNCZ-x) powders are synthesized using a conventional solid-state reaction method. A single orthorhombic phase is observed at x = 0 – 0.03. However, rhombohedral and orthorhombic phases are observed at x = 0.05. The grain growth behavior changes from abnormal grain growth to the suppression of grain growth as the amount of CaZrO3 (CZ) increases. With increasing CZ content, grains become more faceted, and the step-free energy increases. Therefore, the critical growth driving force increases. The grain size distribution broadens with increasing sintering time in KNNCZ-0.05. As a result, some large grains with a driving force larger than the critical driving force for growth exhibit abnormal grain growth behavior during sintering. Therefore, CZ changes the grain growth behavior and microstructure of KNN. Grain growth at the faceted interface of the KNNCZ system occurs via two-dimensional nucleation and growth.

Pb(Zr,Ti)O3 (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. (K,Na)NbO3 (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, (Na,K)NbO3-Ba(Cu,Nb)O3 (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKNBCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan δ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and 20 μC/cm2.

This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of 0.96(K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3-0.04BaZrO3, which has a rhombohedral-tetragonal phase boundary composition. MnO2 and CuO-added 0.96(K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3-0.04BaZrO3 ceramics sintered at a relatively low temperature of 1020 oC show a pure perovskite phase with no secondary phase. As the addition of MnO2 and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of MnO2.

Na+/K+-ATPase is a membrane protein and plays a key role in osmotic regulation in living organisms. In the present study, a cDNA sequence encoding the Na+/K+-ATPase alpha subunit from the monogonont rotifer, Brachionus koreanus was cloned by rapid amplification of cDNA ends technique. To investigate the role of this enzyme in osmotic stress, enzymatic activities of Na+/K+-ATPase were measured after exposure to different salinities for 48 h. The full-length Bk Na+/K+-ATPase cDNA was 3069 bp-long, encoding a 1022-amino acid polypeptide. Bk Na+/K+- ATPase possesses eight membrane spanning regions and five conserved domains. Phylogenetic analysis showed that Bk Na+/K+-ATPase had high identity with those of other species, and was closely clustered with other Brachionus sp. These findings indicate that this protein was conserved both structurally and functionally. B. koreanus Na+/K+-ATPase activity was stimulated in both hyposaline (6 psu) and hypersaline (32 psu) conditions, suggesting that this protein may play a role in osmoregulation. This study would provide better understanding of the physiology of B. koreanus and this enzyme may be useful as a molecular marker for evaluation of osmotic stress in aquatic environment.

New lead-free piezoelectric ceramics 0.96[{Bi0.5 (Na0.84 K0.16)0.5}1-xLax(Ti1-y Nby)O3]-0.04SrTiO3 (BNKT-ST-LN, where x = y = 0.00 ≤ (x = y) ≤ 0.015) were synthesized using the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were investigated as a function of the La and Nb (LN) content. The X-ray diffraction patterns revealed the formation of a single-phase perovskite structure for all the LN-modified BNKT-ST ceramics in this study. The temperature dependence of the dielectric curves showed that the maximum dielectric constant temperature (Tm) shifted towards lower temperatures and the curves became more diffuse with an increasing LN content. At the optimum composition (LN 0.005), a maximum value of remnant polarization (33 C/cm2) with a relatively low coercive field (22 kV/cm) and high piezoelectric constant (215 pC/N) was observed. These results indicate that the LN co-modified BNKT-ST ceramic system is a promising candidate for lead-free piezoelectric materials.

Na+/K+-ATPase, an energy-transducing ion pump, is responsible for maintenance of relatively high concentrations of potassium ions but low concentrations of sodium ions in the cell by transport of these ions across the plasma membrane and participates in transport of various nutrients including glucose, amino acids. and ions. Na+/K+-ATPase consists of α, β, and FXYD subunits, but only α and β subunits are needed for basic functions. FXYD subunit is an auxiliary protein for αβ complex of Na+/K+-ATPase. Our recent study has shown that α (ATP1A1-4) and β (ATP1B1-3) subunits of Na+/K+-ATPase are expressed in the uterine endometrium during the estrous cycle and pregnancy in pigs. In this study, we further determined expression of FXYD (FXYD1-7) subunits of Na+/K+-ATPase in the uterine endometrium during the estrous cycle and pregnancy in pigs. Real-time RT-PCR analysis showed that mRNAs for all subtypes of FXYD subunit were expressed in the uterine endometrium during the estrous cycle and pregnancy in a pregnancy status- and stage-specific fashion. In situ hybridization analysis exhibited that transcripts of all subtypes of FXYD subunit were primarily localized to luminal (LE) and glandular epithelia (GE) during the estrous cycle and early pregnancy and to chorionic membrane (CM) during mid to term pregnancy. RT-PCR analysis showed that FXYD subunits were expressed in conceptuses on D12 and D15 of pregnancy. These results indicate that all subtypes of FXYD subunit are expressed in the uterine endometrium and conceptuses during the estrous cycle and pregnancy in a pregnancy status- and stagespecific manner. These suggest that FXYD may be involved in the establishment and maintenance of pregnancy by regulating the activity of Na+/K+-ATPase in nutrient transport at the maternal-fetal interface in pigs. * This work was supported by the Next Generation BioGreen 21 program (#PJ007997), RDA and the National Research Foundation (NRF #2010-0012304) funded by the Korean Government, Republic of Korea.

Na+/K+-ATPase, an energy-transducing ion pump, is responsible for maintenance of relatively high concentrations of potassium ions but low concentrations of sodium ions in the cell by transport of these ions across the plasma membrane. Na+/K+-ATPase consists of α, β, and γ subunits, but only α and β subunits are needed for basic functions. Na+/K+-ATPase is also involved in regulation of intracellular calcium ion concentration by coupling with Na+/Ca2+ exchanger involved in intracellular calcium extrusion. Our previous study showed that calcium regulatory molecules including Na+/Ca2+ exchanger are expressed in the uterine endometrium during the estrous cycle and pregnancy in pigs, however, expression of Na+/K+-ATPase in the uterine endometrium has not been determined. Thus, we examined expression of α1 (ATP1A1) and β1 (ATP1- B1) subunits of Na+/K+-ATPase in the uterine endometrium during the estrous cycle and pregnancy in pigs. Real-time RT-PCR analysis showed that levels of ATP1A1 m- RNA in the uterine endometrium during the estrous cycle and early pregnancy were higher than those during mid and term pregnancy, and that levels of ATP1B1 mRNA were highest on day (D) 12 of the estrous cycle. In situ hybridization analysis revealed that ATP1A1 and ATP1B1 mRNAs were localized to luminal (LE) and glandular epithelia (GE) in the endometrium. During mid to term pregnancy, localization of ATP1A1 mRNA was confined to LE, GE, and chorionic membrane (CM) of areolae and ATP1- B1 mRNA was localized to LE, GE and CM with the strongest intensity in LE of areolae. Signal intensity of ATP1B1 mRNA in LE was slightly stronger than that in GE. RT-PCR analysis showed that ATP1A1 and ATP1B1 mRNAs were expressed in conceptuses on D12 and D15 of pregnancy. These results showed that ATP1A1 and ATP1B1 were expressed in the uterine endometrium and conceptuses during the estrous cycle and pregnancy in a pregnancy status- and stage-specific manner. These suggest that Na+/K+-ATPase may play a key role in the establishment and maintenance of pregnancy by regulating intracellular concentrations of various ions including calcium at the maternal-fetal interface in pigs.

The influences of Na and K content on the crystal phase, the microstructure and the electrical property of BaTiO3-based thermistors was found to show typical PTC effects. The crystal phase of powder calcined at 1000˚C for 4hrs showed a single phase with BaTiO3, and the crystal structure was transformed from tetragonal to cubic phase according to added amounts of Na and K. In XRD results at 43˚~47˚, the (Ba0.858Na0.071K0.071)(Ti0.9985Nb0.0015)O3-δ showed (002) and (200) peaks but the (Ba0.762Na0.119K0.119)(Ti0.9975Nb0.0025)O3-δ showed (002), (020) and (200) peaks. In sintered bodies, those calcined at 600˚C rather than at 1000˚C were dense, and for certain amounts of Na and K showed rapid decreases in grain size. In relative permittivity, the curie temperature due to the transformation of ferroelectric phase rose with added Na and K but decreased in terms of relative permittivity. In the result of the R-T curve, the sintered bodies have curie temperatures of about 140˚C and the resistivity of sintered bodies have scores of Ω·cm; the jump order of sintered bodies was shown to be more than 104 in powder calcined at 1000˚C.

버네사이트(birnessite)는 약 7Å의 d-spacing을 가지는 대표적인 층상형 산화망간광물로 높은 양이온 교환능력을 가지기 때문에 지하수나 퇴적물 공극 유체의 화학조성을 결정짓는 중요한 역할을 한다. 버네사이트의 양이온 교환 반응 기작을 규명하기 위해서는 층간 내 양이온의 배위 환경과 결정구조에 대한 원자 수준의 이해가 매우 중요하다. 이번 연구에서는 원자 수준의 계산광물학 방법인 고전 분자동역학(classical molecular dynamics; MD) 시뮬레이션을 이용하여 기존 실험에서 보고된 화학조성을 가지는 삼사정계 N a-와 K-버네사이트의 결정구조, 층간 양이온의 배위 환경 및 적층 구조를 계산하였다. 계산 결과는 기존 X-선 실험에서 보고된 격자 상수와 층간 배위 환경을 잘 재현하여 시뮬레이션 방법의 신뢰성을 보여주었으며, X-선 실험만으로는 구분하기 어려운 층간의 양이온과 물 분자 위치를 구별한 원자 수준의 정보를 제공하였다. 망간 팔면체 층의 적층 순서는 동일하지만 층간 내 N a+와 K+의 위치가 서로 상이하고, 층간 양이온의 배위 환 경과 결정구조 간의 상관관계를 보인다. 원자 수준의 분자동역학 시뮬레이션은 버네사이트의 양이온 교환 반응 기작 규명에 크게 기여할 것으로 기대한다.

The adsorption of lithium ion onto zeolite was investigated depending on contact time, initial concentration, cation forms, pH, and adsorption isotherms by employing batch adsorption experiment. The zeolite was converted into different forms such K+, Na+, Mg2+, Ca2+, and Al3+. The zeolite had the higher adsorption capacity of lithium ion in K+ form followed by Na+, Ca2+, Mg2+, and Al3+ forms, which was in accordance with their elctronegativities. The lithium ion adsorption was explained using the Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms and kinetic models. Adsorption rate of lithium ion by zeolite modified in K+ form was controlled by pseudo-second-order and particle diffusion kinetic models. The maximum adsorption capacity obtained from Langmuir isotherm was 17.0 mg/g for zeolite modified in K+ form. The solution pH influenced significantly the lithium ions adsorption capacity and best results were obtained at pH 5-10.

Na+/K+-ATPase, an energy-transducing ion pump, is responsible for maintenance of relatively high concentrations of potassium ions but low concentrations of sodium ions in the cell by transport of these ions across the plasma membrane and participates in transport of various nutrients including glucose, amino acids, and ions. In addition, Na+/K+-ATPase is also involved in regulation of intracellular calcium ion concentration by coupling with Na+/Ca+ exchanger expressed at the maternal-fetal interface in pigs. Na+/K+-ATPase consists of α, β, and FXYD subunits, but only α and β subunits are required for primary functions. FXYD subunit is an auxiliary protein for αβ complex of Na+/K+-ATPase. However, it has not been determined that subunits of Na+/K+-ATPase are expressed in the uterine endometrium during the estrous cycle and pregnancy in pigs. In this study, we determined expression of alpha (ATP1A1-4), beta (ATP1B1-3), and FXYD (FXYD1-7) subunits of Na+/K+-ATPase in the uterine endometrium during the estrous cycle and pregnancy in pigs. Real-time RT-PCR analysis showed that all alpha, beta, and FXYD subunits, except ATP1A3, were expressed in the uterine endometrium during the estrous cycle and pregnancy in a pregnancy status- and stage-specific fashion. In situ hybridization analysis exhibited that ATP1A1, ATP1A4, and ATP1B1 were localized to luminal (LE) and glandular epithelium (GE) during the estrous cycle and early pregnancy, and during mid to term pregnancy. ATP1A1 mRNA was localized to LE, GE, and areolae of the chorioallantois, especially at high levels to LE in areolae regions. ATP1B3 mRNA was detected only in LE during the estrous cycle and pregnancy with highest levels on day (D) 12 of pregnancy. Transcripts of all subtypes of FXYD subunit were primarily localized to LE and GE during the estrous cycle and early pregnancy and to chorionic membrane (CM) during mid to term pregnancy. RT-PCR analysis showed that all subtypes of Na+/K+-ATPase subunits, except ATP1A2, ATP1A3, and ATP1B2 mRNAs, were expressed in conceptuses on D12 and D15 of pregnancy. These results indicate that Na+/K+-ATPase subunits are expressed in the uterine endometrium and conceptuses during the estrous cycle and pregnancy in a pregnancy status- and stage-specific manner. These suggest that Na+/K+-ATPase subunits may be involved in the establishment and maintenance of pregnancy by coordinate regulation of absorption and secretion of nutrients such as glucose, amino acids, and ions at the maternal-fetal interface in pigs.