210 research outputs found
Financing government programmes in economic downturn: policy options
No full textThis author examines the various policy options for the manufacturing sector of the economy in an economic downturn
Design of Lead-Free Antiferroelectric (1 − x)NaNbO3−xSrSnO3 Compositions Guided by First-Principles Calculations
No full textAntiferroelectric materials exhibit a unique electricfield-
induced phase transition, which enables their use in energy
storage, electrocaloric cooling, and nonvolatile memory applications.
However, in many prototype antiferroelectrics this transition
is irreversible, which prevents their implementation. In this work,
we demonstrate a general approach to promote the reversibility of
this phase transition by targeted modification of the material’s local
structure. A new NaNbO3-based composition, namely (1−
x)NaNbO3−xSrSnO3, was designed with a combination of firstprinciples
calculations and experimental characterization. Our
theoretical study predicts stabilization of the antiferroelectric state
over the ferroelectric state with an energy difference of 1.4 meV/f.u.
when 6.25 mol % of SrSnO3 is incorporated into NaNbO3. A series
of samples was prepared using solid-state reactions, and the structural changes upon SrSnO3 incorporation were investigated using
X-ray diffraction and 23Na solid-state nuclear magnetic resonance spectroscopy. The results revealed an increase in the unit cell
volume and a more disordered, yet less distorted local Na environment, which were related to the stabilization of the antiferroelectric
order. The SrSnO3-modified compositions exhibited well-defined double polarization loops and an eight times higher energy storage
density as compared to unmodified NaNbO3. Our results indicate that this first-principles calculations based approach is of great
potential for the design of new antiferroelectric compositions
Magnetocrystalline anisotropy of interstitially and substitutionally Sn-doped MnBi for high temperature permanent magnet applications
No full text© 2023 Author(s). cc-byFirst-principles calculations were performed to calculate the electronic structures of low temperature phase (LTP) MnBi (Mn50Bi50) and substitutionally and interstitially Sn-doped MnBi [Mn50Bi25Sn25, (Mn0.5Bi0.5)66.7Sn33.3]. Brillouin function predicts the temperature dependence of saturation magnetization M(T). Sn substitution for Bi in MnBi (Mn50Bi25Sn25) changes the magnetocrystalline anisotropy constant (Ku) from −0.202 MJ/m3 (the in-plane magnetization) for LTP MnBi to 1.711 MJ/m3 (the out-of-plane magnetization). In comparison, the Ku remains negative but slightly decreases to −0.043 MJ/m3 when Sn is interstitially doped in MnBi [(Mn0.5Bi0.5)66.7Sn33.3]. The Curie temperature (TC) decreases from 716 K for LTP Mn50Bi50 to 445 K for Mn50Bi25Sn25 and 285 K for (Mn0.5Bi0.5)66.7Sn33.3. Mn50Bi25Sn25 has a lower magnetic moment of 5.034 μB/f.u. but a higher saturation magnetization of 64.2 emu/g than (Mn0.5Bi0.5)66.7Sn33.3 with a magnetic moment of 6.609 μB/f.u. and a saturation magnetization of 48.2 emu/g because the weight and volume of the substitutionally Sn-doped MnBi are smaller than the interstitially Sn-doped MnBi. The low Curie temperature and magnetization for Sn-doped MnBi are attributed to the high concentration of Sn. Thus, future study needs to focus on low Sn-concentrated MnBi
Author accepted manuscript: Putting Action into Testing: Enacted Retrieval Benefits Long-Term Retention more than Covert Retrieval.
No full textKubik V, Jonsson F, de Jonge M, Arshamian A. Author accepted manuscript: Putting Action into Testing: Enacted Retrieval Benefits Long-Term Retention more than Covert Retrieval. Quarterly journal of experimental psychology (2006). 2020
BDNF and NT3 Reprogram Human Ectomesenchymal Dental Pulp Stem Cells to Neurogenic and Gliogenic Neural Crest Progenitors Cultured in Serum-Free Medium
No full textBackground/aims: Human Dental Pulp Stem Cells (hDPSCs) are one of the most promising types of cells to regenerate nerve tissues. Standard DMEM+10% fetal bovine serum (FBS) culture medium allows a fast expansion of hDPSC as a surface-adherent cell monolayer. However, the use of FBS also compromises the clinical use of these protocols, and its longterm presence favors hDPSCs differentiation toward mesenchymal cell-derived lineages, at the expense of a reduced capability to generate neural cells. The objective of this work was to characterize the role of neurotrophin signaling on hDPSCs using a serum-free culture protocol, and to assess the neurogenic and gliogenic capacity of hDPSCs for future nerve tissue bioengineering and regeneration. Methods: We compared the different expression of neurotrophin receptors by RT-PCR, Q-PCR, and IF of hDPSCs cultured with different growth media in the presence or absence of serum. Moreover, we assessed the response of hDPSCs to stimulation of neurotransmitter receptors by live cell calcium imaging under these different media. Finally, we compared the osteogenic potential of hDPSCs by Alizarin red staining, and the differentiation to gliogenic/neurogenic fates by immunostaining for Schwann lineage and neuronal lineage markers. We tested a commercial serum-free medium designed for the growth of mesenchymal stem cells: StemPro MSCTM (STP). Results: hDPSCs cultured in STP generated small non-adherent floating dentospheres that showed very low proliferation rates, in contrast to standard FBS-containing medium. We found that hDPSCs grown in STP conditions overexpressed neurotrophin receptor genes NTRK2 (TrkB) and NTRK3 (TrkC). Interestingly, the stimulation of these receptors by adding their respective ligands BDNF and NT-3 to STP medium enhanced the neural crest (NC) progenitor features of cultured hDPSCs. We observed a 10 to 100-fold increase of migratory NC cell markers HNK1 and P75NTR, and a significant overexpression of pluripotency core factors SOX2, OCT4 and NANOG. Moreover, hDPSCs cultured in BDNF/NT-3 supplemented STP showed a largely increased potential to differentiate towards neuronal and Schwann glial lineage cells, assessed by positive immunostaining for DCX, NeuN and S100ß, p75NTR markers, respectively. Conclusion: Our results demonstrate that the use of BDNF and NT-3 combined with STP induced the partial reprogramming of ectomesenchymal hDPSCs to generate early NC progenitor cells, which are far more competent for neuronal and glial differentiation than hDPSCs grown in the presence of FBS.Authors would like to thanks to Díez A. for flow cytometry, Andrade, R. for image acquisition and all staff of the SGIKER of UPV/EHU. This work has been funded by the Spanish Ministry of Economy and Competitiveness SAF2015-70866-R; UPV/EHU (GIU16/66, UFI 11/44), Basque Government (GV/EJ; IT831-13) and by « Ramón y Cajal » program RYC-2013-13450 (JRP) and RYC 2012-11137 (JME); JL obtained a Ph.D. fellowship (PIF/13/268) from the University of the Basque Country. Author Contributions: J.L., I.I., V.U.E., P.G.G., P.C., F.U. and G.I.: conception and design; P.C., G.I., J.R.P., F.U. and J.L.: provision of study materials and manuscript writing; J.R.P., J.M.E., F.U., P.C., and G.I.: financial support; J.L., I.I., U.E.V., F.U. P.C., and G.I.: collection and/or assembly of data, J.L., I.I., U.E.V, P.G.G., J.R.P. and G.I., data analysis and interpretation; J.L., P.C., V.U.E., J.M.E., F.U., I.I., P.G.G., G.I. and J.R.P., manuscript discussion and final approval of manuscript. The authors have no ethical conflicts to disclose
Phosphate and potassium regime of sod podzolic sandy loamy soil depending on food conditions
No full textВ исследованиях на дерново-подзолистой легкосуглинистой почве полная органоминеральная система удобрения обеспечила наиболее благоприятный фосфатный и калийный режим пахотного горизонта дерново-подзолистой легкосуглинистой почвы и максимальную продуктивность зернопропашного севооборота 61,0- 62,5 ц/га к.ед. Исключение из системы удобрения фосфора и калия привело к снижению содержания в почве их подвижных соединений и уменьшению продуктивности зернопропашного севооборота на 6,0-9,8 ц/га к.ед.According to the author full argano-chemical fertilizer system has provided an optimum phosphate and potash regime of arable horizon of podzolic sandy loamy soil and the maximum efficiency of cultivated crop rotation. The exception of phosphorus and potassium from the system of fertilizer has led to maintenance decrease of mobile connections in soil and to efficiency reduction of a cultivated crop rotation on 0,60-0,98 t ha-1 of f.u
Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP
No full textZrMnP and HfMnP single crystals are grown by a self-flux growth technique, and structural as well as temperature dependent magnetic and transport properties are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and HfMnP are ferromagnetic with Curie temperatures around 370 K and 320 K, respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined to be 1.9 μB/f.u. and 2.1 μB/f.u., respectively, at 50 K. The magnetocaloric effect of ZrMnP in terms of entropy change (ΔS) is estimated to be −6.7 kJ m−3 K−1 around 369 K. The easy axis of magnetization is [100] for both compounds, with a small anisotropy relative to the [010] axis. At 50 K, the anisotropy field along the [001] axis is ∼4.6 T for ZrMnP and ∼10 T for HfMnP. Such large magnetic anisotropy is remarkable considering the absence of rare-earth elements in these compounds. The first principle calculation correctly predicts the magnetization and hard axis orientation for both compounds, and predicts the experimental HfMnP anisotropy field within 25%. More importantly, our calculations suggest that the large magnetic anisotropy comes primarily from the Mn atoms, suggesting that similarly large anisotropies may be found in other 3d transition metal compounds.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in: Lamichhane, Tej N., Valentin Taufour, Morgan W. Masters, David S. Parker, Udhara S. Kaluarachchi, Srinivasa Thimmaiah, Sergey L. Bud'ko, and Paul C. Canfield. "Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP." Applied Physics Letters 109, no. 9 (2016): 092402, and may be found at DOI: 10.1063/1.4961933. Posted with permission.</p
Extended Berry Curvature Tail in Ferromagnetic Weyl Semimetals NiMnSb and PtMnSb
No full textHeusler compounds belong to a large family of materials and exhibit numerous physical phenomena with promising applications, particularly ferromagnetic Weyl semimetals for their use in spintronics and memory devices. Here, anomalous Hall transport is reported in the room-temperature ferromagnets NiMnSb (half-metal with a Curie temperature (TC) of 660 K) and PtMnSb (pseudo half-metal with a TC of 560 K). They exhibit 4 µB/f.u. magnetic moments and non-trivial topological states. Moreover, NiMnSb and PtMnSb are the first half-Heusler ferromagnets to be reported as Weyl semimetals, and they exhibit anomalous Hall conductivity (AHC) due to the extended tail of the Berry curvature in these systems. The experimentally measured AHC values at 2 K are 1.8 × 102 Ω−1cm−1 for NiMnSb and 2.2 × 103 Ω−1 cm−1 for PtMnSb. The comparatively large value between them can be explained in terms of the spin-orbit coupling strength. The combined approach of using ab initio calculations and a simple model shows that the Weyl nodes located far from the Fermi energy act as the driving mechanism for the intrinsic AHC. This contribution of topological features at higher energies can be generalized. © 2024 The Author(s). Advanced Science published by Wiley-VCH GmbH
High-temperature ferrimagnetic order triggered metal-to-insulator transition in CaCu<sub>3</sub>Ni<sub>2</sub>Os<sub>2</sub>O<sub>12</sub>
No full textFerromagnetic order-induced insulator-to-metal transitions via the double exchange mechanism have been studied widely. In contrast, ferromagnetic or ferrimagnetic spontaneous magnetization induced metal-to-insulator transitions (MITs), especially occurring above room temperature, remain extremely limited, although such magnetoelectric materials hold great potential for low-loss multifunctional electronic and spintronic devices. Here, a novel 3d/5d hybridized quadruple perovskite oxide, CaCu3Ni2Os2O12, was synthesized. It undergoes long-range Cu2+(↑)–Ni2+(↑)–Os6+(↓) ferrimagnetic order with a high Curie temperature of 393 K, maintaining a saturated magnetization of 2.15 μB/f.u. at 300 K. Intriguingly, an MIT is found to occur concurrently at the Curie temperature. Theoretical analyses reveal that the ferrimagnetic spontaneous order significantly renormalizes the electronic band structure, which can be further modified by electronic correlation and spin–orbit coupling effects, leading to the MIT via the Lifshitz-type mechanism. This work thus provides a paradigm material to realize ferrimagnetic spontaneous magnetization induced MIT at a high critical temperature toward advanced applications. © The Author(s) 2025
Non-zero spontaneous magnetic moment along crystalline b-axis for rare earth orthoferrites
No full text© 2020 Author(s). Rare earth orthoferrites demonstrate great application potentials in spintronics and optical devices due to their multiferroic and magnetooptical properties. In RFeO3, magnetic R3+ undergo a spontaneous spin reorientation in a temperature range determined by R (rare earth), where the magnetic structure changes from Γ2 to Γ4. The b-axis component of their magnetic moment, Mb, is reported in numerous neutron diffraction studies to remain zero at all temperatures. More sensitive magnetometer measurements reveal a small non-zero Mb, which is minute above ∼200 K. Mb increases with cooling and reaches values of ∼10-3 μB/f.u. at temperatures within or below the spin reorientation temperatures. Our results can be explained by assuming the Fe3+ spins as the origin of non-zero Mb, while R3+ spins suppress Mb. The representation analysis of point groups shows that non-zero Mb is associated with a small admixture of the Γ3 phase to Γ2 or Γ4. Such a mixing of the three magnetic phases requires at least a fourth order of the spin Hamiltonian for RFeO3 to describe the non-zero M
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