Identification and comparison of the local physicochemical structures of transition metal-based layered double hydroxides for high performance electrochemical oxygen evolution reactions

Layered double hydroxides(LDHs) have attracted considerable attention as a cost effective alternative to the precious iridium-and ruthenium-based electrocatalysts for an oxygen evolution reaction(OER),a bottleneck of water electrolysis for sustainable hydrogen production.Despite their excellent OER performance,the structural and electronic properties of LDHs,particularly during the OER process,remain to be poorly understood.In this study,a series of LDH catalysts is investigated through in situ X-ray absorption fine structure analyses and density functional theory(DFT) calculations.Our experimental results reveal that the LDH catalyst with equal amounts of Ni and Fe(NF-LDH) exhibits the highest OER activity and catalytic life span when compared with its counterparts having equal amounts of Ni and Co(NC-LDH)and Ni only(Ni-LDH).The NF-LDH shows a markedly enhanced OER kinetics compared to the NC-LDH and the Ni-LDH,as proven by the lower overpotentials of 180,240,and 310 mV,respectively,and the Tafel slopes of 35.1,43.4,and 62.7 mV dec^(-1),respectively.The DFT calculations demonstrate that the lowest overpotential of the NF-LDH is associated with the active sites located at the edge planes of NF-LDH in contrast to those located at the basal planes of Ni-LDH and NC-LDH.The current study pinpoints the active sites on various LDHs and presents strategies for optimizing the OER performance of the LDH catalysts.

Paradoxical carbon dioxide embolism during laparoscopic hepatectomy without intracardiac shunt:A case report

BACKGROUND Laparoscopic hepatectomy has recently become popular because it results in less bleeding than open hepatectomy.However,CO_(2)embolism occurs more frequently.Most CO_(2)embolisms during laparoscopic surgery are self-resolving and non-symptomatic;however,severe CO_(2)embolism may cause hypotension,cyanosis,arrhythmia,and cardiovascular collapse.In particular,paradoxical CO_(2)embolisms are highly likely to cause neurological deficits.We report a case of paradoxical CO_(2)embolism found on transesophageal echocardiography(TEE)during laparoscopic hepatectomy,although the patient had no intracardiac shunt.CASE SUMMARY A 71-year-old man was admitted for laparoscopic left hemihepatectomy.During left hepatic vein ligation,the inferior vena cava was accidentally torn.We observed a sudden drop in oxygen saturation to 85%,decrease in systolic blood pressure(SBP)below 90 mm Hg,and reduction in end-tidal CO_(2)to 24 mm Hg.A“mill-wheel”murmur was auscultated over the precordium.The fraction of inspired oxygen was increased to 100%with 5 cm H2O of positive end-expiratory pressure(PEEP)and hyperventilation was maintained.Norepinephrine infusion was increased to maintain SBP above 90 mm Hg.A TEE probe was inserted,revealing gas bubbles in the right side of the heart,left atrium,left ventricle,and ascending aorta.The surgeon reduced the pneumoperitoneum pressure from 17 to 14 mm Hg and repaired the damaged vessel laparoscopically.Thereafter,the patient’s hemodynamic status stabilized.The patient was transferred to the intensive care unit,recovering well without complications.CONCLUSION TEE monitoring is important to quickly determine the presence and extent of embolism in patients undergoing laparoscopic hepatectomy.

Acute lower extremity arterial thrombosis after intraocular foreign body removal under general anesthesia: A case report and review of literature

BACKGROUND Surgery,which is a major risk factor for venous thrombosis,has rarely been considered a risk factor for arterial thrombosis.Recent studies have suggested that venous and arterial thromboses share common risk factors and have a bidirectional relationship.Accordingly,there is a growing interest in the risk of arterial thrombosis after surgery.We report a case of acute bilateral lower extremity arterial thromboses that developed after a prolonged surgery.CASE SUMMARY A 59-year-old man was hospitalized for intraocular foreign body removal surgery.He was a heavy-drinking smoker and had untreated hypertension and varicose veins in both legs.The operation was unexpectedly prolonged,lasting 4 h and 45 min.Immediately after emergence from general anesthesia,the patient complained of extreme pain in both legs.After the surgical drape was removed,cyanosis was evident in both feet of the patient.The pulse was not palpable,and continuous-wave Doppler signals were inaudible in the bilateral dorsalis pedis and posterior tibial arteries.Computed tomography angiography confirmed acute bilateral thrombotic occlusion of the popliteal arteries,proximal anterior tibial arteries,and tibioperoneal trunks.Arterial pulse returned in both lower limbs after 6 h of heparin initiation.The patient was discharged on postoperative day 26 without any sequelae.CONCLUSION Acute lower extremity arterial thrombosis can occur after surgery.Anesthesiologists should pay particular attention to patients with risk factors for thrombosis.

Unveiling anomalous lattice shrinkage induced by Pi-backbonding in Prussian blue analogues

Transition-metal(TM)-based Prussian blue and its analogues(TM-PBAs) have attracted considerable attention as cathode materials owing to their versatile ion storage capability with tunable working voltages. TM-PBAs with different crystal structures, morphologies, and TM combinations can exhibit excellent electrochemical properties because of their unique and robust host frameworks with well-defined<100> ionic diffusion channels. Nonetheless, there is still a lack of understanding regarding the performance dependence of TM-PBAs on structural changes during charging/discharging processes. In this study, in situ X-ray diffraction and X-ray absorption fine structure analyses elucidate the TMdependent structural changes in a series of TM-PBAs during the charging and discharging processes.During the discharging process, the lattice volume of Fe-PBA increased while those of Ni-and Cu-PBAs decreased. This discrepancy is attributed to the extent of size reduction of the cyanometallate complex([Fe(CN)_(6)]) via pi-backbonding from Fe to C due to redox flips of the low-spin Fe^(3+/2+) ion. This study presents a comprehensive understanding of how TM selection affects capacity acquisition and phase transition in TM-PBAs, a promising class of cathode materials.

Multimodal Metabolic Imaging Reveals Pigment Reduction and Lipid Accumulation in Metastatic Melanoma

Objective and Impact Statement.Molecular signatures are needed for early diagnosis and improved treatment of metastatic melanoma.By high-resolution multimodal chemical imaging of human melanoma samples,we identify a metabolic reprogramming from pigmentation to lipid droplet(LD)accumulation in metastatic melanoma.Introduction.Metabolic plasticity promotes cancer survival and metastasis,which promises to serve as a prognostic marker and/or therapeutic target.However,identifying metabolic alterations has been challenged by difficulties in mapping localized metabolites with high spatial resolution.Methods.We developed a multimodal stimulated Raman scattering and pump-probe imaging platform.By time-domain measurement and phasor analysis,our platform allows simultaneous mapping of lipids and pigments at a subcellular level.Furthermore,we identify the sources of these metabolic signatures by tracking deuterium metabolites at a subcellular level.By validation with mass spectrometry,a specific fatty acid desaturase pathway was identified.Results.We identified metabolic reprogramming from a pigment-containing phenotype in low-grade melanoma to an LD-rich phenotype in metastatic melanoma.The LDs contain high levels of cholesteryl ester and unsaturated fatty acids.Elevated fatty acid uptake,but not de novo lipogenesis,contributes to the LD-rich phenotype.Monounsaturated sapienate,mediated by FADS2,is identified as an essential fatty acid that promotes cancer migration.Blocking such metabolic signatures effectively suppresses the migration capacity both in vitro and in vivo.Conclusion.By multimodal spectroscopic imaging and lipidomic analysis,the current study reveals lipid accumulation,mediated by fatty acid uptake,as a metabolic signature that can be harnessed for early diagnosis and improved treatment of metastatic melanoma.