| 1. |
- Bovornratanaraks, Thiti, et al.
(författare)
-
Ground-state structure of semiconducting and superconducting phases in xenon carbides at high pressure
- 2019
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- The 'missing Xe paradox' is one of the phenomena at the Earth's atmosphere. Studying the 'missing Xe paradox' will provide insights into a chemical reaction of Xe with C. We search the ground-state structure candidates of xenon carbides using the Universal Structure Predictor: Evolutionary Xtallography (USPEX) code, which has been successfully applied to a variety of systems. We predict that XeC2 is the most stable among the convex hull. We find that the I((4) over bar)2m structure of XeC2 is the semiconducting phase. Accurate electronic structures of tetragonal XeC2 have been calculated using a hybrid density functionals HSE06, which gives larger more accurate band gap than a GGA-PBE exchange-correlation functional. Specifically, we find that the I((4) over bar)2m structure of XeC2 is a dynamically stable structure at high pressure. We also predict that the P6/mmm structure of XeC2 is the superconducting phase with a critical temperature of 38 K at 200 GPa. The ground-state structure of xenon carbides is of critical importance for understanding in the missing Xe. We discuss the inference of the stable structures of XeC2. The accumulation of electrons between Xe and C led to the stability by investigating electron localization function (ELF).
|
|
| 2. |
- Gupta, Shantanu, et al.
(författare)
-
Network analysis reveals that the tumor suppressor lncRNA GAS5 acts as a double-edged sword in response to DNA damage in gastric cancer
- 2022
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- The lncRNA GAS5 acts as a tumor suppressor and is downregulated in gastric cancer (GC). In contrast, E2F1, an important transcription factor and tumor promoter, directly inhibits miR-34c expression in GC cell lines. Furthermore, in the corresponding GC cell lines, lncRNA GAS5 directly targets E2F1. However, lncRNA GAS5 and miR-34c remain to be studied in conjunction with GC. Here, we present a dynamic Boolean network to classify gene regulation between these two non-coding RNAs (ncRNAs) in GC. This is the first study to show that lncRNA GAS5 can positively regulate miR-34c in GC through a previously unknown molecular pathway coupling lncRNA/miRNA. We compared our network to several in-vivo/in-vitro experiments and obtained an excellent agreement. We revealed that lncRNA GAS5 regulates miR-34c by targeting E2F1. Additionally, we found that lncRNA GAS5, independently of p53, inhibits GC proliferation through the ATM/p38 MAPK signaling pathway. Accordingly, our results support that E2F1 is an engaging target of drug development in tumor growth and aggressive proliferation of GC, and favorable results can be achieved through tumor suppressor lncRNA GAS5/miR-34c axis in GC. Thus, our findings unlock a new avenue for GC treatment in response to DNA damage by these ncRNAs.
|
|
| 3. |
- Johansson, Börje, et al.
(författare)
-
Cerium; Crystal Structure and Position in The Periodic Table
- 2014
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 6398-
-
Tidskriftsartikel (refereegranskat)abstract
- The properties of the cerium metal have intrigued physicists and chemists for many decades. In particular a lot of attention has been directed towards its high pressure behavior, where an isostructural volume collapse (gamma phase -> alpha phase) has been observed. Two main models of the electronic aspect of this transformation have been proposed; one where the 4f electron undergoes a change from being localized into an itinerant metallic state, and one where the focus is on the interaction between the 4f electron and the conduction electrons, often referred to as the Kondo volume collapse model. However, over the years it has been repeatedly questioned whether the cerium collapse really is isostructural. Most recently, detailed experiments have been able to remove this worrisome uncertainty. Therefore the isostructural aspect of the a-c transition has now to be seriously addressed in the theoretical modeling, something which has been very much neglected. A study of this fundamental characteristic of the cerium volume collapse is made in present paper and we show that the localized reversible arrow delocalized 4f electron picture provides an adequate description of this unique behavior. This agreement makes it possible to suggest that an appropriate crossroad position for cerium in The Periodic Table.
|
|
| 4. |
- Li, Yan-Ling, et al.
(författare)
-
Formation of Nanofoam carbon and re-emergence of Superconductivity in compressed CaC6
- 2013
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. 3331-
-
Tidskriftsartikel (refereegranskat)abstract
- Pressure can tune material's electronic properties and control its quantum state, making some systems present disconnected superconducting region as observed in iron chalcogenides and heavy fermion CeCu2Si2. For CaC6 superconductor (T-c of 11.5 K), applying pressure firstTc increases and then suppresses and the superconductivity of this compound is eventually disappeared at about 18 GPa. Here, we report a theoretical finding of the re-emergence of superconductivity in heavily compressed CaC6. The predicted phase III (space group Pmmn) with formation of carbon nanofoam is found to be stable at wide pressure range with a Tc up to 14.7 K at 78 GPa. Diamond-like carbon structure is adhered to the phase IV (Cmcm) for compressed CaC6 after 126 GPa, which has bad metallic behavior, indicating again departure from superconductivity. Re-emerged superconductivity in compressed CaC6 paves a new way to design new-type superconductor by inserting metal into nanoporous host lattice.
|
|
| 5. |
- Liu, Zeliang, et al.
(författare)
-
Mechanical and electronic properties of van der Waals layered hcp PdH2
- 2020
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanical and electronic properties of palladium dihydrides (PdH2) as a function of pressure were studied by ab initio calculations based on density functional theory (DFT). The ab initio random structure searching technique was employed for screening potential PdH2 crystal structures under high pressure. A hexagonal close packed (hcp) phase of PdH2 with space group P63mc was reported. The structure geometry and elastic constants were calculated as a function of pressure. It was found that H atoms are in the interstitial position of Pd atoms layer at 0 GPa. There is an electronic topology transition of hcp PdH2 at 15 GPa. When pressure exceeds above 15 GPa, one hydrogen atom occupies the tetrahedral site and another hydrogen atom locates in the interstitial position. When the c/a ratio is between 1.765 to 1.875, the hcp PdH2 is mechanically stable, and the Pd-H-2b bond is the major factor that limits the mechanical stability. The elastic constant C-44 is the first one that cannot satisfy the mechanical stability criteria under pressure. The anisotropy parameters are far from 1(one) shows that the hcp PdH2 is a highly anisotropic structure. The electronic structure study indicates that the bonding force between Pd and H atoms along the z-axis direction increases with the increasing pressure. Also, the phonon dispersion study shows that PdH2 is dynamic stability under pressure. The results suggest that hcp PdH2 can be metastable in van der Waals layered structure.
|
|
| 6. |
- Mir, Showkat H., et al.
(författare)
-
Static and Dynamical Properties of heavy actinide Monopnictides of Lutetium
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, density functional theory within the framework of generalized gradient approximation has been used to investigate the structural, elastic, mechanical, and phonon properties of lutetium monopnictides in rock-salt crystal structure. The spin orbit coupling and Hubbard-U corrections are included to correctly predict the essential properties of these compounds. The elastic constants, Young's modulus E, Poisson's ratio v, shear modulus G, anisotropy factor A and Pugh's ratio are computed. We found that all lutetium monopnictides are anisotropic and show brittle character. From the wave velocities along [100], [110] and [111] directions, melting temperature of lutetium monopnictides are predicted. Dynamical stability of these monopnictides has been studied by density functional perturbation theory.
|
|
| 7. |
- Shi, H., et al.
(författare)
-
Role of vacancies, light elements and rare-earth metals doping in CeO2
- 2016
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (O-v) were considered. Our spin-polarized calculations show that C, N, Pr dopants and O-v defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of O-v increasing up to 5%, the CeO2 exhibits a half-metallic properties.
|
|
| 8. |
- Song, Yang, et al.
(författare)
-
Unveiling the Enigma of Matter under Extreme Conditions : From Planetary Cores to Functional Materials
- 2023
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Pressure, as one of the fundamental thermodynamic parameters, can profoundly change the interatomic distances, electronic interactions, chemical bonding and crystal structures, leading to exotic structures and properties of materials. High-pressure techniques have significantly impacted disciplines like physics, chemistry, geology, and life science, creating new materials, advancing knowledge of Earth's interior, and influencing pharmaceutical development. This editorial reviews the latest research published in this Collection, highlighting the potential of high-pressure studies to further our understanding of materials' behavior under extreme conditions.
|
|
| 9. |
- Sun, Weiwei, et al.
(författare)
-
Stability of a new cubic monoxide of Thorium under pressure
- 2015
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Density functional theory has been applied to elucidate the stability of thorium monoxide (ThO). It is found out that the pressure can stabilize the rocksalt phase of ThO, and the transition pressure is estimated between 14 and 22 GPa. The stability of ThO can be attributed due to the gradually filling 5f orbitals at the expense of 7s and 6d electrons in Th metal. For ThO, the pressure induces stronger Th-O bond reflected by the newly established 6d-2p hybridization which is the dominant cause of its stability. The phonon dispersion curves of the rocksalt phase show the positive frequencies which indicates its dynamical stability. Our successful prediction of the stabilization of the metallic ThO has proposed a route to synthesize novel actinide monoxides.
|
|
| 10. |
- Tsuppayakorn-aek, Prutthipong, et al.
(författare)
-
Route to high-T-c superconductivity of BC7 via strong bonding of boron-carbon compound at high pressure
- 2020
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- We have analyzed the compositions of boron-carbon system, in which the BC7 compound is identified as structural stability at high pressure. The first-principles calculation is used to identify the phase diagram, electronic structure, and superconductivity of BC7. Our results have demonstrated that the BC7 is thermodynamically stable in the diamond-like P4m2 structure at a pressure above 244 GPa, and under temperature also. Feature of chemical bonds between B and C atoms is presented using the electron localization function. The strong chemical bonds in diamond-like P4m2 structure are covalent bonds, and it exhibits the s-p hybridization under the pressure compression. The Fermi surface shape displays the large sheet, indicating that the diamond-like P4m2 phase can achieve a high superconducting transition temperature (T-c). The outstanding property of BC7 at 250 GPa has manifested very hig h-T-c of superconductivity as 164 K, indicating that the carbon-rich system can induce the high-T-c value as well.
|
|
