[Pathogen Distribution,Imaging Characteristics,and Establishment and Verification of Risk Prediction Model of Pulmonary Infection with Multi-drug Resistant Organism in Patients with Severe Craniocerebral Injury].

Objective To investigate the pathogen distribution,imaging characteristics,and risk factors of pulmonary infection with multi-drug resistant organism (MDRO) in patients with severe craniocerebral injury,and establish and verify the risk prediction model. Methods A total of 230 patients with severe craniocerebral injury complicated with pulmonary infection were collected retrospectively.According to the 7∶3 ratio,they were randomly assigned into a modeling group (161 patients) and a validation group (69 patients).

Theoretical reflections on the structural polymorphism of the oxygen-evolving complex in the S state and the correlations to substrate water exchange and water oxidation mechanism in photosynthesis.

The structural polymorphism of the oxygen-evolving complex is of great significance to photosynthetic water oxidation. Employing density functional theory calculations, we have made further advisement on the interconversion mechanism of O5 transfer in the S state, mainly focusing on the potentiality of multi-state reactivity and spin transitions. Then, O5 protonation is proven impossible in S for irreversibility of the interconversion, which serves as an auxiliary judgment for the protonation state of O5 in S.

The open-cubane oxo-oxyl coupling mechanism dominates photosynthetic oxygen evolution: a comprehensive DFT investigation on O-O bond formation in the S state.

The dioxygen formation mechanism of biological water oxidation in nature has long been the focus of argument; many diverse mechanistic hypotheses have been proposed. Based on a recent breakthrough in the resolution of the electronic and structural properties of the oxygen-evolving complex in the S state, our density functional theory (DFT) calculations reveal that the open-cubane oxo-oxyl coupling mechanism, whose substrates preferably originate from W2 and O5 in the S state, emerges as the best candidate for O-O bond formation in the S state. This is justified by the overwhelming energetic superiority of this mechanism over alternative mechanisms in both the isomeric open and closed-cubane forms of the MnCaO cluster; spin-dependent reactivity rooted in variable magnetic couplings was found to play an essential role.

How does ammonia bind to the oxygen-evolving complex in the S state of photosynthetic water oxidation? Theoretical support and implications for the W1 substitution mechanism.

Ammonia as a water analogue can bind to the MnCaO cluster of the oxygen-evolving complex in concomitance with ligand substitution and underlying structural transformation. On account of current controversies of the binding site and the absence of the viewpoint of reactivity and mechanistic proofs, we have investigated three modes of NH binding based on our elaborations of the possible reaction mechanisms, in correspondence with experimental observation for the NH-altered g ≈ 2.0 EPR multiline signal.