Observation of the solid-state photo-CIDNP effect in entire cells of cyanobacteria Synechocystis

Cyanobacteria are widely used as model organism of oxygenic photosynthesis due to being the simplest photosynthetic organisms containing both photosystem I and II (PSI and PSII). Photochemically induced dynamic nuclear polarization (photo-CIDNP) 13C magic-angle spinning (MAS) NMR is a powerful tool in understanding the photosynthesis machinery down to atomic level. Combined with selective isotope enrichment this technique has now opened the door to study primary charge separation in whole living cells. Here, we present the first photo-CIDNP observed in whole cells of the cyanobacterium Synechocystis

The solid-state photo-CIDNP effect

The solid-state photo-CIDNP effect is the occurrence of a non-Boltzmann nuclear spin polarization in rigid samples upon illumination. For solid-state NMR, which can detect this enhanced nuclear polarization as a strong modification of signal intensity, the effect allows for new classes of experiments. Currently, the photo- and spin-chemical machinery of various RCs is studied by photo-CIDNP MAS NMR in detail. Until now, the effect has only been observed at high magnetic fields with 13C and 15N MAS NMR and in natural photosynthetic RC preparations in which blocking of the acceptor leads to cyclic electron transfer. In terms of irreversible thermodynamics, the high-order spin structure of the initial radical pair can be considered as a transient order phenomenon emerging under non-equilibrium conditions and as a first manifestation of order in the photosynthetic process. The solid-state photo-CIDNP effect appears to be an intrinsic property of natural RCs. The conditions of its occurrence seem to be conserved in evolution. The effect may be based on the same fundamental principles as the highly optimized electron transfer. Hence, the effect may allow for guiding artificial photosynthesis

Old wine in new bottles: Exploring pragmatism as a philosophical framework for the discipline of coaching

The practice and industry of organizational coaching are now well established, but how it is understood theoretically continues to lag behind. In this paper we analyze possible reasons for this state of affairs and argue that the development of coaching as an academic discipline will benefit from adopting philosophical pragmatism as an overarching theoretical framework. This move will enable coaching academics to utilize the contributions to knowledge that different paradigms generate. Positioning pragmatism as a theory of action we argue that organizational coaching is by default a pragmatic enterprise and provide three examples of the considerable benefits to be gained by conceptualizing it this way. (1) Drawing from the pragmatists’ ideas, particularly those of John Dewey, we demonstrate how the theoretical understanding of organizational coaching can be enhanced by considering its nature as a joint inquiry. (2) Pragmatism suggests development as an ultimate purpose for organizational coaching which also helps to resolve fundamental conceptual debates. (3) In light of the complexity and diversity involved in the way that organizational coaching is practiced, pragmatism offers coaches a useful framework for developing the flexibility required for navigating the multiplicity of influences on their practice

Time-resolved luminescence and photoconductivity of polycrystalline ZnO films

NRC publication: Ye

Luminescent properties of Eu2+ ion in BaMg(1+x)SixAl10Oy films prepared by spray pyrolysis

NRC publication: Ye

Blue, green and red cathodo-luminescence of Y2O3 phosphor films prepared by spray pyrolysis

NRC publication: Ye

Transient photoconductivity properties of tungstenoxide thin films prepared by spray pyrolysis

NRC publication: Ye