Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Extending conducting channels in Fe–N-C by interfacial growth of CNTs with minimal metal loss for efficient ORR electrocatalysis

Achieving a high electrocatalytic performance using a completely metal-free electrocatalyst, preferably based on only carbonaceous materials, remains a challenge. Alternatively, an efficient composite of a carbon nanostructure and a non-noble metal with minimum dependence on a metal holds immense potential. Although single-atom catalysis brings superior performance, its complex synthetic strategy limits its large-scale implementation. Previous investigation has shown that atomic dispersion (Fe–Nx-C) is accompanied by higher metal-loss compared to nanoparticle formation (Fe-NPs–N-C). Therefore, to achieve minimum metal loss, we first incorporated iron nanoparticles (Fe NPs) to N-doped carbon (N-C) and then exposed them to a cheap carbon source, melamine at high temperature, resulting in the growth of carbon nanotubes (CNTs) catalysed by those Fe NPs loaded on N-C (Fe-NPs–N-C). Thermogravimetric analysis showed that the metal-retention in the composite is higher than that in the bare carbon nanotube and even the atomically dispersed Fe-active sites on N-C. The composite material (Fe-NPs–N-C/CNT) shows a high half-wave potential (0.89 V vs. RHE) which is superior to that of commercial Pt/C towards the oxygen reduction reaction (ORR). The enhanced activity is attributed to the synergistic effect of high conductivity of CNTs and active Fe-sites as the composite exceeds the individual electrocatalytic performance shown by Fe-CNTs & Fe-NPs–N-C, and even that of atomically dispersed Fe-active sites on N-C

Compressive strain induced by multiple phase distribution and atomic ordering in PdCu nanoparticles to enhanced ethanol oxidation reaction performance

The catalytic properties of the materials can be altered with different arrangements of atoms, either in ordered or disordered manner. To study this behavior in detail, we have selected compounds based on Pd and Cu with different atomic arrangements and phase distribution. Nanoparticles of Pd$_{1-x}$Cu$_x$ with different atomic ratios and phase states are obtained by a facile one pot solvothermal method. The multiple combinations of structurally ordered and disordered phases are tuned by optimizing several synthetic strategies, which are qualitatively and quantitatively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and transmission electron microscopy measurements. Electrocatalytic ethanol oxidation reaction (EOR) is carried out in alkaline medium for all these synthesized Pd$_{1-x}$Cu$_x$ nanoparticles. It is observed that the EOR activity and stability are enhanced in comparison to the commercial Pd/C catalyst, which can be attributed to the atomic ordering and compressive strain introduced upon optimized phase distribution

Tuning the hybridization and charge polarization in metal nanoparticles dispersed over Schiff base functionalized SBA-15 enhances CO2_2 capture and conversion to formic acid

Different Schiff base functionalized SBA-15 materials were synthesized through condensation reactions between 3-aminopropyltriethoxysilane (APTES) and different aldehydes (glutaraldehyde and butyraldehyde) over a mesoporous silica, SBA-15 (APTES-GLU/SBA-15 and APTES-BUT/SBA-15). Both static and dynamic experiments have been used for testing the CO$_2$ capture efficiency of these materials. The hybridization of the N atom in APTES has been tuned from sp$^3$ to sp$^2$ upon condensation facilitating optimum CO$_2$ capture in the direct synthesis of APTES-GLU/SBA-15. The undesirable oxides of nitrogen have been removed during the synthesis process to improve the CO$_2$ capture efficiency. These materials were employed as supports for Pd–Ag and Pd–Ni bimetallic systems for the selective conversion of the captured CO$_2$ to formic acid (FA) in 0.5 M KHCO$_3$ solution. The Pd–Ni catalyst system exhibited enhanced CO$_2$ to FA conversion activity compared to other heterogeneous systems, which is ∼4 times better than that of the Pd–Ag system in this study. The X-ray absorption studies over the catalyst material confirmed that the relatively electron-deficient Ni in Pd–Ni compared to Ag in Pd–Ag favoured higher charge polarization between the metals in the Pd–Ni system enhancing the CO$_2$ to FA conversion. The experimental observations are well supported by the DFT calculations