Balancing the Kinetic and Thermodynamic Synergetic Effect of Doped Carbon Molecular Sieves for Selective Separation of C2H4/C2H6.

Selective separation of ethylene and ethane (C2H4/C2H6) is a formidable challenge due to their close molecular size and boiling point. Compared to industry-used cryogenic distillation, adsorption separation would offer a more energy-efficient solution when an efficient adsorbent is available. Herein, a class of C2H4/C2H6 separation adsorbents, doped carbon molecular sieves (d-CMSs) is reported which are prepared from the polymerization and subsequent carbonization of resorcinol, m-phenylenediamine, and formaldehyde in ethanol solution. The study demonstrated that the polymer precursor themselves can be a versatile platform for modifying the pore structure and surface functional groups of their derived d-CMSs. The high proportion of pores centered at 3.5 Å in d-CMSs contributes significantly to achieving a superior kinetic selectivity of 205 for C2H4/C2H6 separation. The generated pyrrolic-N and pyridinic-N functional sites in d-CMSs contribute to a remarkable elevation of Henry selectivity to 135 due to the enhancement of the surface polarity in d-CMSs. By balancing the synergistic effects of kinetics and thermodynamics, d-CMSs achieve efficient separation of C2H4/C2H6. Polymer-grade C2H4 of 99.71% purity can be achieved with 75% recovery using the devised d-CMSs as reflected in a two-bed vacuum swing adsorption simulation.

Laser-structured microarray electrodes for durable stretchable lithium-ion battery.

Stretchable lithium-ion batteries (SLIBs) hold great potential as a power source for wearable electronics. A major challenge in the development of SLIBs is fabricating stable and reliable stretchable electrodes. Herein, we develop a novel laser-structured microarray electrodes based SLIBs. An active material film adhered to a planar stretchable current collector is ablated by ultrafast laser into an independent microscale square array, enabling electrodes stretchable. A one-dimensional elastic analytical model is developed to evaluate the stretchability of the microarray electrodes under tensile conditions. The microscale square array adheres to the current collector and keeps intact if the shear stress is less than the adhesion force as well as the tensile stress is less than the tensile strength of the active material. The demonstrated electrodes have a mass active material loading of 10 mg cm-2 and maintain robust electrochemical performance when stretched beyond 500 cycles at 100 % strains. The fabricated SLIBs show a stable capacity of 1.2 mAh cm-2, and over 70 % of initial capacity can be maintained at 100 % strain.

Small lesion depiction and quantification accuracy of oncological 18F-FDG PET/CT with small voxel and Bayesian penalized likelihood reconstruction.

BACKGROUND: To investigate the influence of small voxel Bayesian penalized likelihood (SVB) reconstruction on small lesion detection compared to ordered subset expectation maximization (OSEM) reconstruction using a clinical trials network (CTN) chest phantom and the patients with 18F-FDG-avid small lung tumors, and determine the optimal penalty factor for the lesion depiction and quantification. METHODS: The CTN phantom was filled with 18F solution with a sphere-to-background ratio of 3.81:1. Twenty-four patients with 18F-FDG-avid lung lesions (diameter < 2 cm) were enrolled. Six groups of PET images were reconstructed: routine voxel OSEM (RVOSEM), small voxel OSEM (SVOSEM), and SVB reconstructions with four penalty factors: 0.6, 0.8, 0.9, and 1.0 (SVB0.6, SVB0.8, SVB0.9, and SVB1.0). The routine and small voxel sizes are 4 × 4 × 4 and 2 × 2 × 2 mm3. The recovery coefficient (RC) was calculated by dividing the measured activity by the injected activity of the hot spheres in the phantom study. The SUVmax, target-to-liver ratio (TLR), contrast-to-noise ratio (CNR), the volume of the lesions, and the image noise of the liver were measured and calculated in the patient study. Visual image quality of the patient image was scored by two radiologists using a 5-point scale. RESULTS: In the phantom study, SVB0.6, SVB0.8, and SVB0.9 achieved higher RCs than SVOSEM. The RC was higher in SVOSEM than RVOSEM and SVB1.0. In the patient study, the SUVmax, TLR, and visual image quality scores of SVB0.6 to SVB0.9 were higher than those of RVOSEM, while the image noise of SVB0.8 to SVB1.0 was equivalent to or lower than that of RVOSEM. All SVB groups had higher CNRs than RVOSEM, but there was no difference between RVOSEM and SVOSEM. The lesion volumes derived from SVB0.6 to SVB0.9 were accurate, but over-estimated by RVOSEM, SVOSEM, and SVB1.0, using the CT measurement as the standard reference. CONCLUSIONS: The SVB reconstruction improved lesion contrast, TLR, CNR, and volumetric quantification accuracy for small lesions compared to RVOSEM reconstruction without image noise degradation or the need of longer emission time. A penalty factor of 0.8-0.9 was optimal for SVB reconstruction for the small tumor detection with 18F-FDG PET/CT.

Advances in Post-Combustion CO2 Capture by Physical Adsorption: From Materials Innovation to Separation Practice.

The atmospheric CO2 concentration continues a rapid increase to its current record high value of 416 ppm for the time being. It calls for advanced CO2 capture technologies. One of the attractive technologies is physical adsorption-based separation, which shows easy regeneration and high cycle stability, and thus reduced energy penalties and cost. The extensive research on this topic is evidenced by the growing body of scientific and technical literature. The progress spans from the innovation of novel porous adsorbents to practical separation practices. Major CO2 capture materials include the most widely used industrially relevant porous carbons, zeolites, activated alumina, mesoporous silica, and the newly emerging metal-organic frameworks (MOFs) and covalent-organic framework (COFs). The key intrinsic properties such as pore structure, surface chemistry, preferable adsorption sites, and other structural features that would affect CO2 capture capacity, selectivity, and recyclability are first discussed. The industrial relevant variables such as particle size of adsorbents, the mechanical strength, adsorption heat management, and other technological advances are equally important, even more crucial when scaling up from bench and pilot-scale to demonstration and commercial scale. Therefore, we aim to bring a full picture of the adsorption-based CO2 separation technologies, from adsorbent design, intrinsic property evaluation to performance assessment not only under ideal equilibrium conditions but also in realistic pressure swing adsorption processes.

Three-dimensional hierarchical ZnCo2O4@C3N4-B nanoflowers as high-performance anode materials for lithium-ion batteries.

ZnCo2O4 has become one of the most widely used anode materials due to its good specific capacity, cost-efficiency, high thermal stability and environmental benignity. However, its poor conductivity and cycle stability have limited its practical application in lithium-ion batteries. To overcome these issues, we constructed a 3D nanoflower composite material (ZnCo2O4@C3N4-B) by combining ZnCo2O4 as a framework and B-doped g-C3N4 (g-C3N4-B) as a new carbon source material via a simple hydrothermal method. ZnCo2O4@C3N4-B exhibited exceptional specific capacitance of 919.76 mA h g-1 after 500 cycles at 0.2 A g-1 and a long-term capacity retention of 97.8% after 1000 cycles at 2 A g-1. The high reversible capacity, long cycling life and good rate performance could be attributed to the 3D interconnected architecture and doping of g-C3N4-B. This work provides a simple and general strategy to design high-performance anode materials for lithium-ion batteries to meet the needs of practical applications.