Formate Oxidase (FOx) from Aspergillus oryzae: One Catalyst Enables Diverse H2O2‐Dependent Biocatalytic Oxidation Reactions

An increasing number of biocatalytic oxidation reactions rely on H₂O₂ as a clean oxidant. The poor robustness of most enzymes towards H₂O₂, however, necessitates more efficient systems for in situ H₂O₂ generation. In analogy to the well‐known formate dehydrogenase to promote NADH‐dependent reactions, we here propose employing formate oxidase (FOx) to promote H₂O₂‐dependent enzymatic oxidation reactions. Even under non‐optimised conditions, high turnover numbers for coupled FOx/peroxygenase catalysis were achieved.     

A uniform approach to field quantization

A new method for treating ordinary Bose and Fermi statistics as well as many types of parastatistics is proposed. Number operators are used to distinguish among different types of statistics, and uniqueness results for Bose, Fermi, parabose and parafermi statistics are obtained.     

Acceptor excited states in indium phosphide

Selective donon-acceptor pair luminescence and luminescence excitation spectra reveal acceptor excitations to all excited states of principal quantum number 2, odd as well as even parity. These transition energies are independent of the D-A pair separation R for sufficiently large R and are then identical to those on isolated acceptors. However, they decrease significantly at small R and some splittings are revealed in our measurements on a bulk grown crystal in which the most common contaminant acceptor Zn is dominant. The p state transition energies are used together with the known ionization energy of the Zn acceptor to derive valence band parameters for InP according to the theory of Baldereschi and Lipari. We find γ₁ = 5.6 ± 0.7, γ₂ = 2.0 ± 0.3, γ₃ = 2.4 ± 0.3, where γ₁ is adjusted to fit the cyclotron resonance data of Leotin et al. Some reservations concerning the completeness of this theory are acknowledge. Information on the s acceptor excited state is consistent with that obtained from acceptor bound exciton “two-hole” satellites for this remarkable quality bulk crystal.     

Rhenium(IV) as a sensitizer for two-step blue up-converters

The fluorescence of rhenium(IV) and thulium(III) ions doped singly and together in the most host lattice Cs₂NaYCl₆ is studied. Energy transfer between Re⁴⁺ and Tm³⁺ ions is demonstrated and is shown to provide two-step up-conversion to the ¹D₂ and ¹G₄ levels of the Tm³⁺ ion, both of which emit in the blue.     

Silver Nanoparticles Synthesized by Vapor Deposition onto an Ice Matrix

As a strategy for synthesizing metal nanoparticles, thermally evaporated Ag was deposited onto a thin (1.2nm) crystalline ice layer on hafnia (HfO₂) at 100K. The Ag atoms penetrate into the ice matrix but do not reach the underlying HfO₂ substrate. After controlled thermal desorption of water by heating to 300K, atomic force microscopy reveals Ag particle formation. Their lateral dimensions are between 5 and 20nm and, in many cases, their heights exceed the thickness of the original water layer. Fewer, higher and more regular Ag particles are formed in the presence, as compared to the absence, of ice. This is discussed in terms of two factors – Ag atoms reaching HfO₂ are thermally colder when they arrive from the ice matrix and desorption of water involves formation of liquid droplets, a process that concentrates Ag into the volumes occupied by the water droplets.