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Quantum phase transitions (QPTs) are usually associated with many-body systems in the thermodynamic limit when their ground states show abrupt changes at zero temperature with variation of a parameter in the Hamiltonian. Recently it has been realized that a QPT can also occur in a system composed of only a two-level atom and a single-mode bosonic field, described by the quantum Rabi model (QRM). Here we report an experimental demonstration of a QPT in the QRM using a 171 Yb + ion in a Paul trap. We measure the spin-up state population and the average phonon number of the ion as two order parameters and observe clear evidence of the phase transition via adiabatic tuning of the coupling between the ion and its spatial motion. An experimental probe of the phase transition in a fundamental quantum optics model without imposing the thermodynamic limit opens up a window for controlled study of QPTs and quantum critical phenomena. Quantum phase transition occurs in many-body systems with abrupt changes in the ground state around zero temperature. Here the authors report signatures of quantum phase transition in single trapped ion that can be described using quantum Rabi model.

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is associated with an increased risk of graft failure and severe graft-versus-host disease (GVHD). Recent studies have shown that mesenchymal stromal cells (MSCs) display potent immunosuppressive effects and can support normal hematopoiesis. In a multi-center trial, we co-transplanted culture-expanded donor-derived bone marrow MSCs (BM-MSCs) into 35 children with severe aplastic anemia (SAA) undergoing haplo-HSCT. All 35 patients (100%) achieved hematopoietic reconstitution and showed sustained full donor chimerism. The median time for myeloid engraftment was 14 days (range 10–22 days), while that for platelet engraftment was 18 days (range 9–36 days). The incidence of grade II–IV acute GVHD and chronic GVHD was 25.71 and 22.86%, respectively. The overall survival rate was 85.71% with a median of 22 months (range 3.5–37 months). The combined transplantation of haploidentical HSCs and BM-MSCs into children with SAA without an HLA-identical sibling donor is relatively safe and may represent an effective new therapy to improve survival rates and reduce the risk of graft failure.

Vitamin D deficiency and insufficiency have been found in general population but especially in women of childbearing age. Although Vitamin D can be obtained from food source (few naturally) and produced from skin sunlight exposure, it can come from a reliable source via supplementation. Supplementing 15 µg daily could meet the recommended dietary allowance for 19 years and older and 20 µg for 70 years older. Daily supplementation greater than 100 µg is not recommended. Unlike water-soluble vitamins B and C, Vitamins A, D, E, and K are fat-soluble. This property of Vitamin D affects not only the delivery of it in drink but also absorption at the small intestine and bioavailability (i.e., serum level). This study focused on enhancing the solubility of vitamin D using a novel botanical solubilizer. Using rubusoside (RUB), isolated from stevia and other plants, Vitamin D3 (cholecalciferol; VD3) was experimented for solubility enhancement. VD3 was processed with RUB to form the VD3-RUB structure in powder form. Solubility of this powder in physiologic solutions of water, gastric or intestinal fluid, stability over time, and dilutability for achieving desired supplementation levels were examined. The VD3-RUB complex structure in water solution was characterised for particle size and shape using dynamic light scattering techniques. VD3 in water solution after filtration was quantified on HPLC. VD3 was practically insoluble in water. However, in the presence of 10% w/v RUB as the botanical solubilizer, VD3 became soluble in water to a concentration of 4,500 µg/mL. This water-soluble concentrate appeared clear and was freely dilutable to a drink containing amounts of VD3 ranging from 15 µg to 100 µg. Particle size analysis indicated the presence of approximately 4 nm spherical particles. HPLC analysis of the water solution detected RUB and VD3. These drinks were stable and remained clear and transparent for at least eight weeks. A packet of water-soluble Vitamin D3 powder was also developed for addition to a glass of water in the amount of 15 µg VD3. The packet, similar to the instant coffee powder, produced an instant Vitamin D drink containing the recommended dietary allowance of 15 µg. The water-soluble VD3 powder was also dissolvable in simulated gastric fluid and intestinal fluid, and stable for at least two hours. This solubility enhancement could aid in absorption and improve oral bioavailability, seen in the work with oily ceramides(1) and insoluble curcumin(2). It is especially advantageous for making drinks as the solubilizer is generally regarded as safe by the US FDA.

Three-dimensional (3D) topological Dirac semimetals (TDSs) represent an unusual state of quantum matter that can be viewed as \"3D graphene.\" In contrast to 2D Dirac fermions in graphene or on the surface of 3D topological insulators, TDSs possess 3D Dirac fermions in the bulk. By investigating the electronic structure of Na3Bi with angle-resolved photoemission spectroscopy, we detected 3D Dirac fermions with linear dispersions along all momentum directions. Furthermore, we demonstrated the robustness of 3D Dirac fermions in Na3Bi against in situ surface doping. Our results establish Na3Bi as a model system for 3D TDSs, which can serve as an ideal platform for the systematic study of quantum phase transitions between rich topological quantum states.

An efficient automated toolkit for predicting the mechanical properties of materials can accelerate new materials design and discovery; this process often involves screening large configurational space in high-throughput calculations. Herein, we present the ElasTool toolkit for these applications. In particular, we use the ElasTool to study diversity of 2D materials and heterostructures including their temperature-dependent mechanical properties, and developed a machine learning algorithm for exploring predicted properties.

Exercise is known to have numerous neuroprotective and cognitive benefits, especially pertaining to memory and learning related processes. One potential link connecting them is exercise-mediated hippocampal neurogenesis, in which new neurons are generated and incorporated into hippocampal circuits. The present review synthesizes the extant literature detailing the relationship between exercise and hippocampal neurogenesis, and identifies a key molecule mediating this process, brain-derived neurotrophic factor (BDNF). As a member of the neurotrophin family, BDNF regulates many of the processes within neurogenesis, such as differentiation and survival. Although much more is known about the direct role that exercise and BDNF have on hippocampal neurogenesis in rodents, their corresponding cognitive benefits in humans will also be discussed. Specifically, what is known about exercise-mediated hippocampal neurogenesis will be presented as it relates to BDNF to highlight the critical role that it plays. Due to the inaccessibility of the human brain, much less is known about the role BDNF plays in human hippocampal neurogenesis. Limitations and future areas of research with regards to human neurogenesis will thus be discussed, including indirect measures of neurogenesis and single nucleotide polymorphisms within the BDNF gene.

Besides the cusp, polar cap, and auroral oval, the nightside subauroral zone has also recently been reported as a source region of the ionospheric oxygen outflows. However, the detailed mass and energy sources of these ions remain open questions. Here, we address this issue from the perspective of the response of conjugate hemispheres. Investigation of Van Allen Probes data demonstrates a notable preference of oxygen outflows from the nightside subauroral zone from the sunlit hemisphere. This characteristic eliminates the possibility of nightside auroral precipitation playing a significant role, as it is more prominent in darkness. Instead, it highlights sunlight‐induced ionization as the mass source and enhanced plasma waves from the magnetotail as the energy source. The results presented here further support the nightside subauroral zone as an independent source of magnetospheric oxygen ions. Plain Language Summary Single‐charged oxygen ions, believed to ultimately originate from the ionosphere, are the main carriers of the ring current during severe space weather, including super geomagnetic storms and substorms. Therefore, comprehending where and how they come from is crucial for understanding the magnetosphere and space weather. Recent studies have reported the nightside subauroral zone as a source region, besides the usually cited cusp, polar cap, and auroral oval. However, the detailed mechanisms for the subauroral oxygen outflows remain open questions. In this study, we address this issue by studying how opposite hemispheres react simultaneously in subauroral oxygen outflow events observed by the Van Allen Probes. Data analysis reveals that these outflows tend to occur in the local summer hemisphere, where the nightside subauroral ionosphere receives more sunlight compared to the opposite hemisphere. This feature rules out nightside auroral precipitation playing a significant role, as it is more noticeable in the dark. Instead, it points to sunlight‐induced ionization as the source of mass and enhanced plasma waves from the magnetotail as the source of energy. Our findings reinforce the idea that the nightside subauroral zone is an important source of ionospheric oxygen outflows. Key Points The Van Allen Probes have observed oxygen outflows from the nightside subauroral ionosphere in a single hemisphere Statistics reveal a preference for the outflows in sunlit hemisphere, distinguishing them from auroral outflows more prominent in darkness This preference highlights sunlight‐induced ionization and waves from the magnetotail as the source of mass and energy

Weyl semimetals are crystalline solids that host emergent relativistic Weyl fermions and have characteristic surface Fermi-arcs in their electronic structure. Weyl semimetals with broken time reversal symmetry are difficult to identify unambiguously. In this work, using angle-resolved photoemission spectroscopy, we visualized the electronic structure of the ferromagnetic crystal Co₃Sn₂S₂ and discovered its characteristic surface Fermi-arcs and linear bulk band dispersions across the Weyl points. These results establish Co₃Sn₂S₂ as a magnetic Weyl semimetal that may serve as a platform for realizing phenomena such as chiral magnetic effects, unusually large anomalous Hall effect and quantum anomalous Hall effect.

A systematic spectroscopic analysis of the principal members of the iron pnictide family of superconductors reveals a substantial spin–orbit splitting. Spin–orbit coupling is a fundamental interaction in solids that can induce a broad range of unusual physical properties, from topologically non-trivial insulating states to unconventional pairing in superconductors 1 , 2 , 3 , 4 , 5 , 6 , 7 . In iron-based superconductors its role has, so far, not been considered of primary importance, with models based on spin- or orbital fluctuations pairing being used most widely 8 , 9 , 10 . Using angle-resolved photoemission spectroscopy, we directly observe a sizeable spin–orbit splitting in all the main members of the iron-based superconductors. We demonstrate that its impact on the low-energy electronic structure and details of the Fermi surface topology is stronger than that of possible nematic ordering 11 , 12 , 13 . The largest pairing gap is supported exactly by spin–orbit-coupling-induced Fermi surfaces, implying a direct relation between this interaction and the mechanism of high-temperature superconductivity.

Cracks in solid-state materials are typically irreversible. Here we report electrically reversible opening and closing of nanoscale cracks in an intermetallic thin film grown on a ferroelectric substrate driven by a small electric field (~0.83 kV/cm). Accordingly, a nonvolatile colossal electroresistance on–off ratio of more than 10 8 is measured across the cracks in the intermetallic film at room temperature. Cracks are easily formed with low-frequency voltage cycling and remain stable when the device is operated at high frequency, which offers intriguing potential for next-generation high-frequency memory applications. Moreover, endurance testing demonstrates that the opening and closing of such cracks can reach over 10 7 cycles under 10-μs pulses, without catastrophic failure of the film. Electric-field-induced cracks are generally detrimental to functionality of ferroelectric ceramics. Liu et al. use an intermetallic alloy and ferroelectric oxide junction to mediate the reversible formation of cracks at nanoscales, resulting in colossal electroresistance modulation for memory applications.