The average valence, ValO, of the oxygen anions in the perovskite oxide BaTiO3, was found using O1s photoelectron spectra to be −1.55. This experimental result is close to the theoretical value for BaTiO3 (−1.63) calculated by Cohen [Nature 358, 136 (1992)] using density functional theory. Using the same approach, we obtained values of ValO for several monoxides, and investigated the dependence of ValO and the ionicity on the second ionization energy, V(M2+), of the metal cation. We found that the dependence of the ionicity on V(M2+) in this work is close to that reported by Phillips [Rev. Mod. Phys. 42, 317 (1970)]. We therefore suggest that O1s photoelectron spectrum measurements should be accepted as a general experimental method for estimating the ionicity and average valence of oxygen anions.

Method for estimating ionicities of oxides using O1s photoelectron spectra

Owing to their high safety and reversibility, aqueous microbatteries using zinc anodes and an acid electrolyte have emerged as promising candidates for wearable electronics. However, a critical limitation that prevents implementing zinc chemistry at the microscale lies in its spontaneous corrosion in an acidic electrolyte that causes a capacity loss of 40% after a ten-hour rest. Widespread anti-corrosion techniques, such as polymer coating, often retard the kinetics of zinc plating/stripping and lack spatial control at the microscale. Here, a polyimide coating that resolves this dilemma is reported. The coating prevents corrosion and hence reduces the capacity loss of a standby microbattery to 10%. The coordination of carbonyl oxygen in the polyimide with zinc ions builds up over cycling, creating a zinc blanket that minimizes the concentration gradient through the electrode/electrolyte interface and thus allows for fast kinetics and low plating/stripping overpotential. The polyimide's patternable feature energizes microbatteries in both aqueous and hydrogel electrolytes, delivering a supercapacitor-level rate performance and 400 stable cycles in the hydrogel electrolyte. Moreover, the microbattery is able to be attached to human skin and offers strong resistance to deformations, splashing, and external shock. The skin-mountable microbattery demonstrates an excellent combination of anti-corrosion, reversibility, and durability in wearables.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.202007497

A Patternable and In Situ Formed Polymeric Zinc Blanket for a Reversible Zinc Anode in a Skin-Mountable Microbattery.

Radiotherapy (RT) is a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors. Although great success has been achieved on radiotherapy, there is still an intractable challenge to enhance radiation damage to tumor tissue and reduce side effects to healthy tissue. Radiosensitizers are chemicals or pharmaceutical agents that can enhance the killing effect on tumor cells by accelerating DNA damage and producing free radicals indirectly. In most cases, radiosensitizers have less effect on normal tissues. In recent years, several strategies have been exploited to develop radiosensitizers that are highly effective and have low toxicity. In this review, we first summarized the applications of radiosensitizers including small molecules, macromolecules, and nanomaterials, especially those that have been used in clinical trials. Second, the development states of radiosensitizers and the possible mechanisms to improve radiosensitizers sensibility are reviewed. Third, the challenges and prospects for clinical translation of radiosensitizers in oncotherapy are presented.

/pdf/application-of-radiosensitizers-in-cancer-radiotherapy-34lsbq2b49.pdf

Application of Radiosensitizers in Cancer Radiotherapy.

Fabricating structured 2D Ti3AlC2 MAX dispersed TiO2 heterostructure with Ni2P as a cocatalyst for efficient photocatalytic H2 production

Effect of rare earth elements on low temperature magnetic properties of Ni and Co-ferrite nanoparticles

Three models of magnetic ordering in typical magnetic materials

The oxygen vacancy model has been used to explain the magnetic and electrical transport properties of dilute magnetic semiconductors and resistive switching. In particular, some authors have claimed that they found a symmetric peak corresponding to the oxygen vacancies in O1s photoelectron spectra. In this paper, using X-ray photoelectron spectra with argon ion etching, it is shown that this symmetric peak may also be interpreted as being related to O1− anions, rather than to oxygen vacancies.

Presence of monovalent oxygen anions in oxides demonstrated using X-ray photoelectron spectra

Powder samples of the ferrites MxNi1−xFe2O4 (M = Cr, Co and 0.0 ≤ x ≤ 0.3) were prepared using a chemical co-precipitation method. X-ray diffraction analysis showed that the two series of samples had a single-phase cubic spinel structure. It was found that the magnetic moments (μexp) per formula of samples measured at 10 K decreased when Cr substituted for Ni, but increased when Co substituted for Ni, in spite of the fact that the magnetic moments of Cr2+ (4 μB) and Co2+ (3 μB) are higher than that of Ni2+ (2 μB). With the assumption that the magnetic moments of Cr2+ and Cr3+ lie antiparallel to those of the Fe, Co, and Ni cations in the same sublattices of spinel ferrites, the dependences on the Cr (Co) doping level of the sample magnetic moments at 10 K were fitted successfully, using the quantum-mechanical potential barrier model earlier proposed by our group. For the two series of samples, the fitted magnetic moments are close to the experimental results.

Study of cation magnetic moment directions in Cr (Co) doped nickel ferrites

Powder samples of the ferrites MxMn1-xFe2O4 (M = Zn, Mg, Al) were prepared using a chemical co-precipitation method. X-ray diffraction analysis showed that the three series of samples had a single-phase cubic spinel structure and that there was a decrease in the lattice parameters with increasing x. There were different dependences on the doping level x of the magnetic moments (μexp) for the three series of samples measured at 10 K. We found a non-monotonic behavior for μexp as a function x for the Zn doped samples with a maximum at x = 0.4, while μexp decreased monotonically with increasing x for the Mg and Al doped samples. On the basis of the O2p itinerant electron model, the magnetic moment direction of the Mn3+ cations is expected to be antiparallel to those of the Mn2+ and Fe cations in these samples. With this assumption, the curves of μexp versus x for the three series of samples were fitted using a quantum-mechanical potential barrier model earlier proposed by our group, and the cation distributi...

L. Q. Wu

Papers

Method for estimating ionicities of oxides using O1s photoelectron spectra

Three models of magnetic ordering in typical magnetic materials

Presence of monovalent oxygen anions in oxides demonstrated using X-ray photoelectron spectra

Study of cation magnetic moment directions in Cr (Co) doped nickel ferrites

Study of cation distributions in spinel ferrites MxMn1-xFe2O4 (M=Zn, Mg, Al)