Dielectric Properties of Unfilled Tetragonal Tungsten Bronze Ba4PrFe(0.5)Nb(9.5)O(30) Ceramics

In order to found new dielectrics ceramics in tungsten bronze structure, unfilled tungsten bronze（TB） ceramics with nominal formula Ba4PrFe（0.5）Nb（9.5）O（30） were prepared by the solid state reaction method. The microstructure and dielectric properties were studied using powder X-ray diffraction, field emission scanning electron microscope, and variable temperature dielectric test system. The results show that the ceramics have a single phase and belong to the space group of P4bm with the cell of a = b = 12.4839（3） ？, c = 3.9409（5） ？, V = 614.192（2） ？3. The frequency dependent dielectrics properties show that the ceramics have a Debye-like relaxation at room temperature, while the temperature dependent dielectrics properties indicate that the ceramics are a relaxor and the relaxation is due to the nanopolars and oxygen vacancies. The ceramics have a potential application in electronic ceramics as temperature-stable multilayer ceramic capacitors.

Environmentally Induced Under-Development of Seeds in Garden Pea and Its Underlying Factors

Under-development of pea (Pisum sativum L.) seeds in normally developed pods, resulting in “unfilled pods”, has been a serious problem in the greenhouse cultivation in Wakayama Prefecture, one of the major regions of pea cultivation in Japan. This phenomenon appears to be induced by low temperature and low solar irradiation during pea growing season. This study examined the relationship between this seed under-development and sucrose-to-starch metabolism in developing seeds and pods after flowering. The starch content, ADP-glucose pyrophosphorylase (AGPase) and sucrose synthase activities of a pea cultivar, Kishuusui, were monitored through seed development in shading-treatment plot and in control plot. Results showed that the present treatment induced the depression of starch accumulation and AGPase activity in developing seeds compared with control, which might cause the occurrence of under-development of seeds and unfilled pods. Surplus carbohydrates from source organs might be stored in pod walls, as expected from higher starch level and AGPase activity in treated pod walls. The necessity of thermostable AGPase variants in pea to prevent the unfilled-pod problem was discussed.

Regulating f orbital of Tb electronic reservoir to activate stepwise and dual-directional sulfur conversion reaction

The sluggish kinetics in multistep sulfur redox reaction with different energy requirements for each step,is considered as the crucial handicap of lithium–sulfur(Li–S)batteries.Designing an electron reservoir,which can dynamically release electron to/accept electron from sulfur species during dis-charge/charge,is the ideal strategy for realizing stepwise and dual-directional polysulfide electrocatalysis.Herein,a single Tb^(3+/4+)oxide with moderate unfilled f orbital is synthetized as an electron reservoir to optimize polysulfide adsorption via Tb–S and N…Li bonds,reduce activation energy barrier,expe-dite electron/Li+transport,and selectively catalyze both long-chain and short-chain polysulfide conversions during charge and discharge.As a result,Tb electron reservoir enables stable operation of low-capacity decay(0.087%over 500 cycles at 1 C),high sulfur loading(5.2 mg cm^(2))and electrolyte-starved(7.5μL mg^(-1))Li–S batteries.This work could unlock the potential of f orbital engineering for high-energy battery systems.