Feasibility of a Hybrid Risk-Adapted Monitoring System in Investigator-Sponsored Trials in Cancer.

BACKGROUND: We assessed the feasibility of a hybrid monitoring system (minimal on-site monitoring + strategic central monitoring) used at the academic research office at Asan Medical Center (Seoul, Korea) in monitoring investigator-sponsored oncology trials. METHODS: Monitoring findings in three oncology trials conducted between 2014 and 2017 were compared. A confirmatory source data verification (SDV) was carried out in the low-risk trial and compared with the central monitoring findings. The economic advantages of central monitoring were tested by calculating the monitoring hours per patient. RESULTS: A total of 50, 118, 228 patients were enrolled in the high-, intermediate-, and low-risk trials, respectively. The high-risk trial was monitored through 42 on-site visits (1299 findings); the intermediate-risk trial had 79 monitorings (on-site, 24%; central, 76%; 1464 findings); the low-risk trial had 197 monitorings (on-site, 4%; central, 96%; 3364 findings). Central monitoring was more effective than on-site monitoring in revealing minor errors such as "missing case report forms" and "data outliers" (both P < 0.0001), and showed comparable results in revealing major issues such as investigational product compliance and delayed reporting of serious adverse events (both P > 0.05). Confirmatory SDV in the low-risk trial revealed more findings than central monitoring in the "inconsistent data" and "inappropriate adverse event" categories. The total monitoring hours per patient were lower in the intermediate- and low-risk trials than in the high-risk trial (8.1 and 7.3 vs. 14.3 h, respectively). CONCLUSION: Our hybrid monitoring system showed acceptable feasibility in revealing both major and minor issues in multi-center oncology investigator-sponsored trials.

Additional Lithium Storage on Dynamic Electrode Surface by Charge Redistribution in Inactive Ru Metal.

Beyond a traditional view that metal nanoparticles formed upon electrochemical reaction are inactive against lithium, recently their electrochemical participations are manifested and elucidated as catalytic and interfacial effects. Here, ruthenium metal composed of ≈5 nm nanoparticles is prepared and the pure ruthenium as a lithium-ion battery anode for complete understanding on anomalous lithium storage reaction mechanism is designed. In particular, the pure metal electrode is intended for eliminating the electrochemical reaction-derived Li2 O phase accompanied by catalytic Li2 O decomposition and the interfacial lithium storage at Ru/Li2 O phase boundary, and thereby focusing on the ruthenium itself in exploring its electrochemical reactivity. Intriguingly, unusual lithium storage not involving redox reactions with electron transfer but leading to lattice expansion is identified in the ruthenium electrode. Size-dependent charge redistribution at surface enables additional lithium adsorption to occur on the inactive but more environmentally sensitive nanoparticles, providing innovative insight into dynamic electrode environments in rechargeable lithium chemistry.

Triggered reversible phase transformation between layered and spinel structure in manganese-based layered compounds.

Irreversible phase transformation of layered structure into spinel structure is considered detrimental for most of the layered structure cathode materials. Here we report that this presumably irreversible phase transformation can be rendered to be reversible in sodium birnessite (NaxMnO2·yH2O) as a basic structural unit. This layered structure contains crystal water, which facilitates the formation of a metastable spinel-like phase and the unusual reversal back to layered structure. The mechanism of this phase reversibility was elucidated by combined soft and hard X-ray absorption spectroscopy with X-ray diffraction, corroborated by first-principle calculations and kinetics investigation. These results show that the reversibility, modulated by the crystal water content between the layered and spinel-like phases during the electrochemical reaction, could activate new cation sites, enhance ion diffusion kinetics and improve its structural stability. This work thus provides in-depth insights into the intercalating materials capable of reversible framework changes, thereby setting the precedent for alternative approaches to the development of cathode materials for next-generation rechargeable batteries.

Revisiting Solid Electrolyte Interphase on the Carbonaceous Electrodes Using Soft X-ray Absorption Spectroscopy.

It is widely accepted that solid electrolyte interphase (SEI) layer of carbonaceous material is formed by irreversible decomposition reaction of an electrolyte, and acts as a passivation layer to prevent further decomposition of the electrolyte, ensuring reliable operation of a Li-ion battery. On the other hand, recent studies have reported that some transition metal oxide anode materials undergo reversible decomposition of an organic electrolyte during cycling, which is completely different from carbonaceous anode materials. In this work, we revisit the electrochemical reaction of an electrolyte that produces SEI layer on the surface of carbonaceous anode materials using soft X-ray absorption spectroscopy. We discover that the reversible formation and decomposition of SEI layer are also able to occur on the carbonaceous materials in both Li- and Na-ion battery systems. These new findings on the unexpected behavior of SEI in the carbonaceous anode materials revealed by soft X-ray absorption spectroscopy would be highly helpful in more comprehensive understanding of the interfacial chemistry of carbonaceous anode materials in Li- and Na-ion batteries.

Probing the Additional Capacity and Reaction Mechanism of the RuO2 Anode in Lithium Rechargeable Batteries.

The structural changes and electrochemical behavior of RuO2 are investigated by using in situ XRD, X-ray absorption spectroscopy, and electrochemical techniques to understand the electrochemical reaction mechanism of this metal oxide anode material. Intermediate phase-assisted transformation of RuO2 to LiRuO2 takes place at the start of discharge. Upon further lithiation, LiRuO2 formed by intercalation decomposes to nanosized Ru metal and Li2 O by a conversion reaction. A reversible capacity in addition to its theoretical capacity is observed on discharging below 0.5 V during which no redox activity involving Ru is observed. TEM, X-ray photoelectron spectroscopy, and the galvanostatic intermittent titration technique are used to probe this additional capacity. The results show that the additional capacity is a result of Li storage in the grain boundary between nanosized Ru metal and Li2 O. Findings of this study provide a better understanding of the quantitative share of capacity by a unique combination of intercalation, conversion, and interfacial Li storage in a RuO2 anode.

Lithium-ion transport through a tailored disordered phase on the LiNi0.5 Mn1.5 O4 surface for high-power cathode materials.

The phase control of spinel LiNi0.5 Mn1.5 O4 was achieved through surface treatment that led to an enhancement of its electrochemical properties. Li(+) diffusion inside spinel LiNi0.5 Mn1.5 O4 could be promoted by modifying the surface structure of LiNi0.5 Mn1.5 O4 through phosphidation into a disordered phase (Fd3m) that allows facile Li(+) transport. Phosphidated LiNi0.5 Mn1.5 O4 showed a significantly enhanced electrochemical performance, even at high rates exceeding 10 C, demonstrating that the improved kinetics (related to the amount of Mn(3+) ) can render LiNi0.5 Mn1.5 O4 competitive as a high-power cathode material for electric vehicles and hybrid electric vehicles.