Physicochemical conditions for effective hydrogen isotope storage and delivery in a uranium bed

This paper proposes physicochemical conditions for effective hydrogen isotope storage and delivery in a uranium bed. Effective physicochemical conditions for tritium storage and delivery are obtained by manipulating initial depleted uranium (DU) temperatures and hydrogen pressures and applying three distinct operation scenarios. These novel physicochemical conditions and operation scenarios enable higher and more constant hydrogen recovery and delivery rates. The results presented can be used to facilitate the storage and delivery of tritium for environmental protection and waste management in nuclear fission reactors, and for future commercial use in isotope industries and nuclear fusion fuel systems.     

One-pot cascade deacetalization and nitroaldol condensation over acid–base bifunctional ZIF-8 catalyst

Designing an elegant cascade catalyst is one of the challenging issues in catalyst research because the different or sometimes antagonistic active sites should catalyze the reaction in a consecutive manner without any adverse effects. In particular, complex synthetic methods have been envisaged to avoid unfavorable neutralization between acid and base sites in the preparation of acid–base bifunctional catalysts. In this work, acid–base bifunctional catalytic activity of ZIF-8 was evaluated for one-pot cascade deacetalization and nitroaldol condensation, and the reaction performance was compared with those of other metal–organic framework (MOF) catalysts. Although MOFs bearing strong Lewis acid sites on their metal nodes efficiently promoted the first deacetalization step, they were either totally ineffective (Cu-BTC, Fe-BTC, and MIL-53) or unsatisfactory (MIL-101 and UiO-66) to produce final product in the second base-catalyzed reaction step. On the other hand, ZIF-8 was more efficient at catalyzing the second nitroaldol condensation step, and the selectivity of the final product was substantially improved to as high as 56.4%. The enhanced selectivity clearly demonstrates the promising potential of ZIF-8 as a site-isolated acid–base bifunctional catalyst. However, the gradual catalyst deactivation, resulting from weakening of both acid and base sites during a reaction revealed by characterization of used catalyst, should be improved to extend its use to other versatile cascade or tandem reactions.     

Conversion of squid pens to chitosanases and dye adsorbents via Bacillus cereus

Research on Chemical Intermediates - The purpose of this study was to reclaim squid pens for the production of chitosanases and biosorbents of food colorants and industrial dyes via Bacillus cereus...     

Preferential Cation Vacancies in Perovskite Hydroxide for the Oxygen Evolution Reaction

The oxygen evolution reaction (OER) is an ideal model to study the relationship between the activity and the surface properties of catalysts. Defect engineering has been extensively developed to tune the electrocatalytic activity for OER. Compared to the anion vacancies in metal oxides, cation vacancies are more challenging to selectively generate, and the insight into the structure and activity of cation vacancies‐rich catalysts are lacked. Herein, using SnCoFe perovskite hydroxide as a precursor, abundant Sn vacancies on the surface were preferentially produced by Ar plasma. Sn vacancies could be preferentially produced as confirmed by the X‐ray absorption spectra, probably owing to the lower lattice energy and weaker chemical bonds of Sn(OH)₄. The Sn vacancies promoted the exposure of active CoFe sites, resulting in an amorphous surface layer, modulated the conductivity, and thus enhanced the OER performance.     

Scalable Wet Deposition of Zeolite AEI with a High Degree of Preferred Crystal Orientation

Producing zeolite films with controlled preferred orientation on an industrial scale is a long‐standing challenge. Herein we report on a scalable approach to the direct wet deposition of zeolite thin films and membranes while maintaining a high degree of control over the preferred crystal orientation. As a proof of concept, thin films comprising aluminophosphate zeolite AEI were cast on silicon wafer or porous alumina substrates. Electrical properties and separation performance of the zeolite thin films/membranes were engineered through controlling degree of preferred crystal orientation.     

Analysis of velocity-matched Ti:LiNbO3 optical intensity modulators with an extended point-matching method

The point-matching method has been extended to analyse a travelling-wave electrode structure for shielded velocity-matched Ti:LiNbO₃ Mach-Zehnder optical modulators. This method provides a simple and fast approach to analysing the coplanar waveguide with buffer layer, cover shield, and electrodes of finite thickness. The calculated characteristic impedances and microwave effective indices agree well with those obtained using the spectral domain technique and the finite-element method. It is found that in the coplanar waveguide without cover shield it is difficult to achieve velocity matching. The coplanar waveguide with cover shield can be used to achieve velocity matching, but the corresponding characteristic impedance is lower than 50. Both velocity matching and impedance matching can be obtained using a narrow centre electrode. The calculated electric field has been used to estimate the modulation efficiency of the device. Velocity matching can be achieved by adjusting the height of the cover shield, but a compromise must be made between high interaction efficiency and low microwave reflection when choosing the buffer layer thickness and the electrode thickness.