Comparison between percutaneous and laparoscopic microwave ablation of hepatocellular carcinoma

Background: Based on patient and tumor characteristics, some authors favor laparoscopic microwave ablation (LMWA) over the percutaneous approach (PMWA) for treatment of hepatocellular carcinoma (HCC). We compared the two techniques in terms of technique efficacy, local tumor progression (LTP) and complication rates. Study design: A retrospective comparative analysis was performed on 91 consecutive patients (102 HCC tumors) who underwent PMWA or LMWA between October 2014 and May 2019. Technique efficacy at one-month and LTP at follow-up were assessed by contrast-enhanced CT/MRI. Kaplan–Meier estimates and Cox regression were used to compare LTP-free survival (LTPFS). Results: At baseline analysis, LMWA group showed higher frequency of multinodular disease (p < .001) and average higher energy delivered over tumor size (p = .033); PMWA group showed higher rates of non-treatment-naïve patients (p = .001), patients with Hepatitis-C (p = .03) and BCLC-A1 disease (p = .006). Technique efficacy was not significantly different between the two groups (p = .18). Among effectively treated patients, 75 (83 tumors) satisfied ≥6 months follow-up, 54 (57 tumors) undergoing PMWA and 21 (26 tumors) LMWA. LTP occurred in 14/83 cases (16.9%): 12 after PMWA (21.1%) and 2 after LMWA (7.7%). At univariate analysis, technique did not correlate to LTPFS (p = .28). Subgroup analysis showed a trend toward worse LTPFS after PMWA of subcapsular tumors (p = .16). Major complications were observed in six patients (6.6%), 2 after PMWA and 4 after LMWA (3.2% vs 14.3%, p = .049). Conclusions: Technical approach did not affect LTPFS. Complications were reported more frequently after LMWA. Despite higher complication rates, LMWA seems a valid option for treatment of subcapsular tumors

Direct in situ spectroscopic evidence of the crucial role played by surface oxygen vacancies in the O2-sensing mechanism of SnO2

NAP-XPS characterisation of SnO2 under operando conditions shows that resistance change, band bending and surface O-vacancy concentration are correlated with ambient O2 concentration, challenging current preconceptions of gas sensor function

Compensation of x-ray mirror distortion by cooling temperature control

Synchrotron radiation is emitted from a bending magnet source in a wide ray fan which is collected by the first optical element in a beamline. In order to maximize angular acceptance, and hence flux, it is beneficial to increase the length of this mirror and optical design requirements may necessitate that the optical surface be over 1 m in length. Such mirrors also require cooling as they may be subject to high heat loads from the incident radiation. Two beamlines, B07 and B24, at Diamond Light Source, UK, use 1.4 m long toroidal mirrors which utilize a similar side-clamped cooling manifold design. While this scheme has been successful in providing effective cooling of the mirror, it has also been discovered that it introduces deformation of the radius of curvature which is sufficient to alter the focusing characteristics of the mirror. At both beamlines, the horizontal focus of the beam was found to differ by up to several meter from the design position at the exit slit which resulted in poor flux throughput, reduced energy resolution and other side effects. A pencil beam scan method has been used to diagnose this issue and infer the position of the focus and mirror shape. Through the use of a standalone chiller to alter the temperature of the water within the cooling loop, it has been possible to correct the distortion of the radius and restore the focus to its nominal position

Identifying the catalyst chemical state and adsorbed species during methanol conversion on copper using ambient pressure X-ray spectroscopies

Methanol is a promising chemical for the safe and efficient storage of hydrogen, where methanol conversion reactions can generate a hydrogen-containing gas mixture. Understanding the chemical state of the catalyst over which these reactions occur and the interplay with the adsorbed species present is key to the design of improved catalysts and process conditions. Here we study polycrystalline Cu foils using ambient pressure X-ray spectroscopies to reveal the Cu oxidation state and identify the adsorbed species during partial oxidation (CH3OH + O2), steam reforming (CH3OH + H2O), and autothermal reforming (CH3OH + O2 + H2O) of methanol at 200 °C surface temperature and in the mbar pressure range. We find that the Cu surface remains highly metallic throughout partial oxidation and steam reforming reactions, even for oxygen-rich conditions. However, for autothermal reforming the Cu surface shows significant oxidation towards Cu2O. We rationalise this behaviour on the basis of the shift in equilibrium of the CH3OH* + O* ⇌ CH3O* + OH* caused by the addition of H2O

Direct in situ spectroscopic evidence of the crucial role played by surface oxygen vacancies in the O2-sensing mechanism of SnO2

Conductometric gas sensors (CGS) provide a reproducible gas response at a low cost but their operation mechanisms are still not fully understood. In this paper, we elucidate the nature of interactions between SnO2, a common gas-sensitive material, and O2, a ubiquitous gas central to the detection mechanisms of CGS. Using synchrotron radiation, we investigated a working SnO2 sensor under operando conditions via near-ambient pressure (NAP) XPS with simultaneous resistance measurements, and created a depth profile of the variable near-surface stoichiometry of SnO2−x as a function of O2 pressure. Our results reveal a correlation between the dynamically changing surface oxygen vacancies and the resistance response in SnO2-based CGS. While oxygen adsorbates were observed in this study we conclude that these are an intermediary in oxygen transport between the gas phase and the lattice, and that surface oxygen vacancies, not the observed oxygen adsorbates, are central to response generation in SnO2-based gas sensors

On the stability of isolated iridium sites in N-rich frameworks against agglomeration under reducing conditions

Stabilization of single metal atoms is a persistent challenge in heterogeneous catalysis. Especially supported late transitions metals are prone to undergo agglomeration to nanoparticles under reducing conditions. In this study, nitrogen-rich covalent triazine frameworks (CTFs) are used to immobilize iridium complexes. Upon reduction at 400°C, immobilized Ir(acac)(COD) on CTF does not form nanoparticles but transforms into a highly active Ir single atom catalyst. The resulting catalyst systems outperforms both the immobilized complex and supported nanoparticles in the dehydrogenation of formic acid as probe reaction. This superior performance could be traced back to decisive changes of the coordination geometry positively influencing activity, selectivity and stability. Spectroscopic analysis reveals an increase of electron density on the cationic iridium site by donation from the CTF macroligand after removal of the organic ligand sphere from the Ir(acac)(COD) precursor complex upon reductive treatment. This work demonstrates the ability of nitrogen moieties to stabilize molecular metal species against agglomeration and opens avenues for catalysts design using isolated sites in high-temperature applications under reducing atmosphere

A PM10 chemically characterised nation-wide dataset for Italy. Geographical influence on urban air pollution and source apportionment

: Urban textures of the Italian cities are peculiarly shaped by the local geography generating similarities among cities placed in different regions but comparable topographical districts. This suggested the following scientific question: can such different topographies generate significant differences on the PM10 chemical composition at Italian urban sites that share similar geography despite being in different regions? To investigate whether such communalities can be found and are applicable at Country-scale, we propose here a novel methodological approach. A dataset comprising season-averages of PM10 mass concentration and chemical composition data was built, covering the decade 2005-2016 and referring to urban sites only (21 cities). Statistical analyses, estimation of missing data, identification of latent clusters and source apportionment modelling by Positive Matrix Factorization (PMF) were performed on this unique dataset. The first original result is the demonstration that a dataset with atypical time resolution can be successfully exploited as an input matrix for PMF obtaining Country-scale representative chemical profiles, whose physical consistency has been assessed by different tests of modelling performance. Secondly, this dataset can be considered a reference repository of season averages of chemical species over the Italian territory and the chemical profiles obtained by PMF for urban Italian agglomerations could contribute to emission repositories. These findings indicate that our approach is powerful, and it could be further employed with datasets typically available in the air pollution monitoring networks

Experimental measurement and prediction of ionic liquid ionisation energies

Ionic liquid (IL) valence electronic structure provides key descriptors for understanding and predicting IL properties. The ionisation energies of 60 ILs are measured and the most readily ionised valence state of each IL (the highest occupied molecular orbital, HOMO) is identified using a combination of X-ray photoelectron spectroscopy (XPS) and synchrotron resonant XPS. A structurally diverse range of cations and anions were studied. The cation gave rise to the HOMO for nine of the 60 ILs presented here, meaning it is energetically more favourable to remove an electron from the cation than the anion. The influence of the cation on the anion electronic structure (and vice versa) were established; the electrostatic effects are well understood and demonstrated to be consistently predictable. We used this knowledge to make predictions of both ionisation energy and HOMO identity for a further 516 ILs, providing a very valuable dataset for benchmarking electronic structure calculations and enabling the development of models linking experimental valence electronic structure descriptors to other IL properties, e.g. electrochemical stability. Furthermore, we provide design rules for the prediction of the electronic structure of ILs