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- Bassani, Carlos L., et al.
(författare)
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Nanocrystal Assemblies : Current Advances and Open Problems
- 2024
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Ingår i: ACS Nano. - 1936-0851. ; 18:23, s. 14791-14840
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Forskningsöversikt (refereegranskat)abstract
- We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states. We also examine dynamic effects and optimization of assembly protocols. Finally, we discuss promising material functions and examples of their realization with nanocrystal assemblies.
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| 2. |
- Ben-David, Yael, et al.
(författare)
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RIC3, the cholinergic anti-inflammatory pathway, and neuroinflammation
- 2020
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Ingår i: International Immunopharmacology. - : ELSEVIER. - 1567-5769 .- 1878-1705. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels having many functions including inflammation control, as part of the cholinergic anti-inflammatory pathway. Genome wide association studies implicated RIC3, a chaperone of nAChRs, in multiple sclerosis (MS), a neuroinflammatory disease. To understand the involvement of RIC3 in inflammatory diseases we examined its expression, regulation, and function in activated immune cells. Our results show that immune activation leads to dynamic changes in RIC3 expression, in a mouse model of MS and in human lymphocytes and macrophages. We also show similarities in the expression dynamics of RIC3 and CHRNA7, encoding for the alpha 7 nAChR subunit. Homomeric alpha 7 nAChRs were shown to mediate the anti-inflammatory effects of cholinergic agonists. Thus, similarity in expression dynamics between RIC3 and CHRNA7 is suggestive of functional concordance. Indeed, siRNA mediated silencing of RIC3 in a mouse macrophage cell line eliminates the anti-inflammatory effects of cholinergic agonists. Furthermore, we show increased average expression of RIC3 and CHRNA7 in lymphocytes from MS patients, and a strong correlation between expression levels of these two genes in MS patients but not in healthy donors. Together, our results are consistent with a role for RIC3 and for the mechanisms regulating its expression in inflammatory processes and in neuroinflammatory diseases.
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| 4. |
- Pakhira, Santanu, et al.
(författare)
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Suppression of antiferromagnetic order and strong ferromagnetic spin fluctuations in Ca(Co1−xNix)2−yAs2 single crystals
- 2021
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 104:9
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Tidskriftsartikel (refereegranskat)abstract
- CaCo2−yAs2 is a unique itinerant system having strong magnetic frustration. Here, we report the effect of electron doping on the physical properties resulting from Ni substitutions for Co. The single crystals of Ca(Co1−xNix)2−yAs2 were characterized by single-crystal x-ray diffraction, energy-dispersive x-ray spectroscopy, magnetization M versus temperature T, magnetic field H, time t, and heat capacity Cp(H,T) measurements. The A-type antiferromagnetic (AFM) transition temperature TN=52 K for x=0 decreases to 22 K with only 3% Ni substitution and is completely suppressed for x>0.16. For 0.11≤x≤0.52 strong ferromagnetic (FM) fluctuations develop as revealed by magnetic susceptibility χ(T)=M(T)/H measurements. For x=0.11 and 0.16 competing AFM and FM interactions result in a reentrant spin-glass behavior below TN, as evidenced by the observations of thermomagnetic hysteresis and magnetic relaxation. Enhanced FM fluctuations are also found for the x=0.21 and 0.31 crystals, where χc increases significantly at low T. A large χ anisotropy in these compositions where χc is up to a factor of two larger than χab suggests that the FM spin fluctuations are quasi-1D in nature. Weak ferromagnetic contributions to the magnetization are found at T=2 K for x=0.11–0.31. Heat-capacity Cp(T) measurements reveal the presence of FM quantum spin fluctuations for 0.11≤x≤0.52, where a logarithmic T dependence of Cp(T)/T is observed at low T. The suppression of AFM order by the development of strong FM fluctuations in Ca(Co1−xNix)2−yAs2 crystals suggests the presence of a FM quantum-critical point at x≈0.20. Our density-functional theory (DFT) calculations confirm that FM fluctuations are enhanced by Ni substitutions for Co in CaCo2−yAs2. The Sommerfeld electronic heat-capacity coefficient is enhanced for x=0, 0.21, and 0.42 by about a factor of two compared to DFT calculations of the density of states (DOS) at the Fermi energy, suggesting an enhancement of the DOS from electron-phonon and/or electron-electron interactions. The crystals with x>0.52 do not exhibit FM spin fluctuations or magnetic order at T≥1.8 K, which was found from the DFT calculations to arise from a Stoner transition. Superconductivity is not observed above 1.8 K for any of the compositions. Neutron-diffraction studies of crystals with x=0.11 and 0.16 in the crossover regime (0.1≲x≲0.2) show no evidence of A-type ordering as observed in the parent compound with x=0. Furthermore, no other common magnetic structures, such as ferromagnetic (FM), helical stacking of in-plane FM layers, or in-plane AFM structure, are found with an ordered moment greater than the uncertainty of 0.05μB per transition-metal atom.
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