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- ItemSynthesis and Characterization of Oxide Chloride Sr2VO3Cl, a Layered S = 1 Compound(Washington, DC : ACS Publications, 2023) Sannes, Johnny A.; Kizhake Malayil, Ranjith K.; Corredor, Laura T.; Wolter, Anja U. B.; Grafe, Hans-Joachim; Valldor, MartinThe mixed-anion compound with composition Sr2VO3Cl has been synthesized for the first time, using the conventional high-temperature solid-state synthesis technique in a closed silica ampule under inert conditions. This compound belongs to the known Sr2TmO3Cl (Tm = Sc, Mn, Fe, Co, Ni) family, but with Tm = V. All homologues within this family can be described with the tetragonal space group P4/nmm (No. 129); from a Rietveld refinement of powder X-ray diffraction data on the Tm = V homologue, the unit cell parameters were determined to a = 3.95974(8) and c = 14.0660(4) ร , and the atomic parameters in the crystal structure could be estimated. The synthesized powder is black, implying that the compound is a semiconductor. The magnetic investigations suggest that Sr2VO3Cl is a paramagnet at high temperatures, exhibiting a ฮผeff = 2.0 ฮผB V-1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (ฮธCW = โ50 K), in line with the V-O-V advantageous super-exchange paths in the V-O layers. Specific heat capacity studies indicate two small anomalies around 5 and 35 K, which however are not associated with long-range magnetic ordering. 35Cl ss-NMR investigations suggest a slow spin freezing below 4.2 K resulting in a glassy-like spin ground state.
- ItemEnvironment-Assisted Invariance Does Not Necessitate Bornโs Rule for Quantum Measurement(Basel : MDPI, 2023) Mertens, Lotte; van Wezel, JasperThe argument of environment-assisted invariance (known as envariance) implying Bornโs rule is widely used in models for quantum measurement to reason that they must yield the correct statistics, specifically for linear models. However, it has recently been shown that linear collapse models can never give rise to Bornโs rule. Here, we address this apparent contradiction and point out an inconsistency in the assumptions underlying the arguments based on envariance. We use a construction in which the role of the measurement machine is made explicit and shows that the presence of envariance does not imply that every measurement will behave according to Bornโs rule. Rather, it implies that every quantum state allows a measurement machine to be constructed, which yields Bornโs rule when measuring that particular state. This resolves the paradox and is in agreement with the recent result of objective collapse models necessarily being nonlinear.
- ItemRelease of Bioactive Molecules from Graphene Oxide-Alginate Hybrid Hydrogels: Effect of Crosslinking Method(Basel : MDPI, 2023) Madeo, Lorenzo Francesco; Curcio, Manuela; Iemma, Francesca; Nicoletta, Fiore Pasquale; Hampel, Silke; Cirillo, GiuseppeTo investigate the influence of crosslinking methods on the releasing performance of hybrid hydrogels, we synthesized two systems consisting of Graphene oxide (GO) as a functional element and alginate as polymer counterpart by means of ionic gelation (physical method, ๐ป๐๐ดโ๐บ๐) and radical polymerization (chemical method, ๐ป๐ถ๐ดโ๐บ๐). Formulations were optimized to maximize the GO content (2.0 and 1.15% for ๐ป๐๐ดโ๐บ๐ and ๐ป๐ถ๐ดโ๐บ๐, respectively) and Curcumin (CUR) was loaded as a model drug at 2.5, 5.0, and 7.5% (by weight). The physico-chemical characterization confirmed the homogeneous incorporation of GO within the polymer network and the enhanced thermal stability of hybrid vs. blank hydrogels. The determination of swelling profiles showed a higher swelling degree for ๐ป๐ถ๐ดโ๐บ๐ and a marked pH responsivity due to the COOH functionalities. Moreover, the application of external voltages modified the water affinity of ๐ป๐ถ๐ดโ๐บ๐, while they accelerated the degradation of ๐ป๐๐ดโ๐บ๐ due to the disruption of the crosslinking points and the partial dissolution of alginate. The evaluation of release profiles, extensively analysed by the application of semi-empirical mathematical models, showed a sustained release from hybrid hydrogels, and the possibility to modulate the releasing amount and rate by electro-stimulation of ๐ป๐ถ๐ดโ๐บ๐.
- ItemExchange Bias Effect of Ni@(NiO,Ni(OH)2) Core/Shell Nanowires Synthesized by Electrochemical Deposition in Nanoporous Alumina Membranes(Basel : MDPI, 2023) Garcรญa, Javier; Gutiรฉrrez, Ruth; Gonzรกlez, Ana S.; Jimรฉnez-Ramirez, Ana I.; รlvarez, Yolanda; Vega, Vรญctor; Reith, Heiko; Leistner, Karin; Luna, Carlos; Nielsch, Kornelius; Prida, Vรญctor M.Tuning and controlling the magnetic properties of nanomaterials is crucial to implement new and reliable technologies based on magnetic hyperthermia, spintronics, or sensors, among others. Despite variations in the alloy composition as well as the realization of several post material fabrication treatments, magnetic heterostructures as ferromagnetic/antiferromagnetic coupled layers have been widely used to modify or generate unidirectional magnetic anisotropies. In this work, a pure electrochemical approach has been used to fabricate core (FM)/shell (AFM) Ni@(NiO,Ni(OH)2) nanowire arrays, avoiding thermal oxidation procedures incompatible with integrative semiconductor technologies. Besides the morphology and compositional characterization of these core/shell nanowires, their peculiar magnetic properties have been studied by temperature dependent (isothermal) hysteresis loops, thermomagnetic curves and FORC analysis, revealing the existence of two different effects derived from Ni nanowiresโ surface oxidation over the magnetic performance of the array. First of all, a magnetic hardening of the nanowires along the parallel direction of the applied magnetic field with respect their long axis (easy magnetization axis) has been found. The increase in coercivity, as an effect of surface oxidation, has been observed to be around 17% (43%) at 300 K (50 K). On the other hand, an increasing exchange bias effect on decreasing temperature has been encountered when field cooling (3T) the oxidized Ni@(NiO,Ni(OH)2) nanowires below 100 K along their parallel lengths.
- ItemHigh-efficiency and reliable same-parent thermoelectric modules using Mg3Sb2-based compounds(Oxford : Oxford University Press, 2023) Jiang, Meng; Fu, Yuntian; Zhang, Qihao; Hu, Zhongliang; Huang, Aibin; Wang, Shuling; Wang, Lianjun; Jiang, WanThermoelectric modules can convert waste heat directly into useful electricity, providing a clean and sustainable way to use fossil energy more efficiently. Mg3Sb2-based alloys have recently attracted considerable interest from the thermoelectric community due to their nontoxic nature, abundance of constituent elements and excellent mechanical and thermoelectric properties. However, robust modules based on Mg3Sb2 have progressed less rapidly. Here, we develop multiple-pair thermoelectric modules consisting of both n-type and p-type Mg3Sb2-based alloys. Thermoelectric legs based on the same parent fit into each other in terms of thermomechanical properties, facilitating module fabrication and ensuring low thermal stress. By adopting a suitable diffusion barrier layer and developing a new joining technique, an integrated all-Mg3Sb2-based module demonstrates a high efficiency of 7.5% at a temperature difference of 380 K, exceeding the state-of-the-art same-parent thermoelectric modules. Moreover, the efficiency remains stable during 150 thermal cycling shocks (โผ225 h), demonstrating excellent module reliability.