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IntroductionMany studies have shown that monocyte human leukocyte antigen-DR (mHLA-DR) expression may be a good predictor for mortality in severe septic patients. On the contrary, other studies found mHLA-DR was not a useful prognostic marker in severe sepsis. Few studies have taken changes of mHLA-DR during treatment into consideration. The objective of this study was to estimate the prognostic value of changes of mHLA-DR to predict mortality in severe sepsis.MethodsIn this prospective observational study, mHLA-DR was measured by flow cytometry in peripheral blood from 79 adult patients with severe sepsis. mHLA-DR levels were determined on day 0, 3, 7 after admission to the surgical intensive care unit (SICU) with a diagnosis of severe sepsis. ΔmHLA-DR3 and ΔmHLA-DR7 were defined as the changes in mHLA-DR value on day 3 and day 7 compared to that on day 0. Data were compared between 28-day survivors and non-survivors. Receiver operating characteristic (ROC) curves were plotted to measure the performance and discriminating threshold of ΔmHLA-DR3, ΔmHLA-DR7, ΔmHLA-DR7-3, mHLA-DR0, mHLA-DR3 and mHLA-DR7 in predicting mortality of severe sepsis.ResultsROC curve analysis showed that ΔmHLA-DR3 and ΔmHLA-DR7 were reliable indicators of mortality in severe sepsis. A ΔmHLA-DR3 value of 4.8% allowed discrimination between survivors and non-survivors with a sensitivity of 89.0% and a specificity of 93.7%; similarly, ΔmHLA-DR7 value of 9% allowed discrimination between survivors and non-survivors with a sensitivity of 85.7% and a specificity of 90.0%. Patients with ΔmHLA-DR3 ≤4.8% had higher mortality than those with ΔmHLA-DR3 > 4.8% (71.4% vs. 2.0%, OR 125.00, 95% CI 13.93 to 1121.67); patients with ΔmHLA-DR7 ≤9% had higher mortality than those with ΔmHLA-DR7 > 9% (52.9% vs. 2.0%, OR 54.00, 95% CI 5.99 to 486.08). The mean change of mHLA-DR significantly increased in the survivor group with the passage of time; from day 0 to day 3 and day 7, changes were 6.45 and 16.90 (P < 0.05), respectively.ConclusionsThe change of mHLA-DR over time may be a reliable predictor for mortality in patients with severe sepsis.

The NiOOH catalyst as obtained dynamically from electrodeposition of Ni 2+ (aq) in the borate-containing electrolyte was observed to exhibit much higher oxygen evolution activity at a near-neutral pH range (7−9) compared to other NiO x -based materials. Here, we demonstrate that this intriguing high activity is owing to the high concentration of Ni cationic vacancy on the nascent ultra-small NiOOH particles (<3 nm). By using first-principles calculations, we compute the thermodynamics of Ni dissolution and clarify the mechanism of oxygen evolution reaction (OER) on the γ-NiOOH surface. We show that ( i) ∼4% Ni cations on the surface of γ-NiOOH dissolve at pH = 7 and 1.73 V versus reversible hydrogen electrode; (ii) on the pristine γ-NiOOH surface, OER proceeds via the "lattice peroxide" mechanism (*H 2 O → *OH → *O−O latt H* → O−O latt → O 2 ) with an overpotential of 0.70 V; (iii) in the presence of Ni cationic vacancies, OER proceeds via the "hydroperoxide" mechanism (*OH + *H 2 O → *2OH → *OOH → O 2 ) with an overpotential of 0.40 V. Our electronic structure and geometrical structure analyses demonstrate that the structural flexibility at the four-coordinated Ni site nearby Ni vacancy, featuring the ability to bind two terminal oxo species, is key to boost the activity. Considering the presence of the active OOH intermediate, our theory thus implies that the ultra-small oxide nanoclusters with ample cation vacancies could be a paradigm in catalyst design for oxidation reactions.

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Photocatalysts for CO2 photoreduction such as GaP often suffer from poor stability due to a high reduction environment as required for CO2 reduction, e.g., −1.9 V vs SCE to reach the current density of 10 mA/cm2 at pH = 5.8 on p-GaP (Nature1978275115). The coating with stable oxides appears to be a promising solution, but many fundamental aspects such as the epitaxial relation between materials, the coating layer thickness, and the consequent photoactivity remain unknown. Here, using a thin TiO2-coated GaP as a model system, we have systematically investigated the dependence of photoactivity upon the deposition of TiO2 on GaP surfaces. By combining the modified phenomenological theory of Martensitic crystallography and a stochastic surface walking global search, we resolve the atomic-level structures of the interface between GaP and TiO2, a set of coherent interfaces between TiO2 and GaP ((001)TiO2//(100)GaP, (101)TiO2//(110)GaP, and (112)TiO2//(100)GaP). Due to the negligible interface strain, the epitaxial TiO2 coating layer is found to be as stable as bulk TiO2 even with a thickness below 1 nm, suggesting the presence of the well-ordered interface is a critical condition for promoting electron–hole separation in photocatalysis. We demonstrate that a photoelectron generated from GaP bulk can readily tunnel through the thin TiO2 layer (0.5–3 nm) without significant decay, which can decrease the CO2 reduction barrier significantly by 1.02 eV as compared to that without electron tunneling; alternatively, the photoelectron may also undergo lattice hopping to the TiO2 surface to promote hydrogen evolution as required in water splitting. Our results rationalize the recent finding that the high CO2 reduction ability of TiO2 coated GaP at a critical thickness (<10 nm). Using the theoretical framework developed here, we predict that the TiO2 coating strategy could be extended naturally to a range of photoabsorbing materials, including zincblende semiconductors and organic–inorganic hybrid halide perovskites, which can achieve a coherent interface and exhibit photoactivity toward water splitting and CO2 reduction.

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