Interfacial Superconductivity Achieved in Parent AEFe2As2 (AE = Ca, Sr, Ba) by a Simple and Realistic Annealing Route.

Materials with interfaces often exhibit extraordinary phenomena exemplified by rich physics, such as high-temperature superconductivity and enhanced electronic correlations. However, demonstrations of confined interfaces to date have involved intensive effort and fortuity, and no simple path is consistently available. Here, we report the achievement of interfacial superconductivity in the nonsuperconducting parent compounds AEFe2As2, where AE = Ca, Sr, or Ba, by simple subsequent annealing of the as-grown samples in an atmosphere of As, P, or Sb. Our results indicate that the superconductivity originates from electron transfer at the interface of the hybrid van der Waals heterostructures, consistent with the two-dimensional superconducting transition observed. The observations suggest a common origin of interfaces for the nonbulk superconductivity previously reported in the AEFe2As2 compound family and provide insight for the further exploration of interfacial superconductivity.

Contribution to the reduction-induced fluorescence enhancement of natural organic matter: Aromatic ketones outweigh quinones.

This work involves the comparison of the fluorescence excitation - emission matrices of different low-molecular-weight carbonyl compounds and natural organic matter (NOM). The aim is to determine if quinone or aromatic ketone groups are more responsible for the reduction-induced fluorescence enhancement of NOM. After reduction, the aromatic ketones showed a significantly greater fluorescence change than the quinones, proving that the former play a more important role. Further analysis of the fluorescence of the NOM samples after re-oxidization by oxygen with a Cu2+ catalyst, provided additional reliable evidence in support of the dominant role of aromatic ketones in the fluorescence change. This work demonstrates that aromatic ketone moieties should be given more attention when considering the physicochemical properties of NOM and related environmental processes.

A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation.

Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.

Charge-Transfer Modeling and Polarization DRT Analysis of Proton Ceramics Fuel Cells Based on Mixed Conductive Electrolyte with the Modified Anode-Electrolyte Interface.

A charge-transfer model considering the mixed conductivities of proton, oxygen ion, and free electron in interface-modified La2Ce2O7 (LCO) electrolyte is designed to analyze the characteristics of proton ceramics fuel cell in the field of the open-circuit voltage, internal short-circuit current, proton-transfer number, discharging curves, oxygen/hydrogen partial pressure, and cell efficiencies. The properties of anode-supported single cells with the modified anode-electrolyte interface containing an in situ formed doped BaCeO3 reaction layer are compared to those of unmodified cells at various temperatures T and H2O partial pressures. Besides, the electrochemical impedance spectroscopies of both cells were investigated by the relaxation time distribution to distinguish different polarization processes. The results indicated that the reaction interface layer can effectively reduce the internal short-circuit current density and increase the proton-transfer number of electrolytes. Importantly, the NiO-BaZr0.1Ce0.7Y0.2O3-δ anode can also make more protons transfer from anode to cathode and participate in the cathodic reaction for LCO-based proton ceramics fuel cell. The polarization of the cell decreases with the increase of water partial pressure, which leads to the increase of open-circuit voltage and cell efficiency.