ABSTRACT
A zeolitic imidazole framework (ZIF-67) template-derived cobalt@nitrogen-doped carbon-sulfur composite (ZIF-Co@NCS) was synthesized using a freeze-drying method and explored for lithium-sulfur (Li-S) batteries. Material characterizations confirmed the formation of the ZIF-Co@NCS composite. To fabricate the Li-S battery in a coin-type CR-2032 cell, the as-synthesized ZIF-Co@NCS composite having a sulfur content of â¼65% was used as a cathode material and coupled with a lithium metal anode. This battery demonstrated exceptional cycling stability over 600 charge-discharge cycles with a steady capacity of 550 mAh g-1 at 0.05 C-rate. The good electrochemical performance of the cathode was ascribed to the nanofeatures associated with the freeze-dried porous carbon structure, which offered enough space for the sulfur cathode. The enhanced trapping of polysulfide facilitated by the presence of the Co-N sites in the ZIF-Co@NCS composite led to excellent cycling stability. The derived cathode composite showed a high specific capacity, outstanding rate capability, and excellent cyclic stability rendering it a promising candidate for high-performance Li-S batteries. Detailed Li+ ion charge storage examined by means of Dunn's method revealed a significant capacitive mode of charge storage both at peak currents and nonpeak currents. The post-mortem analysis of the cycled cathode using X-ray diffraction and scanning electron microscopy at different depth-of-discharge (DOD) values revealed the stepwise formation of discharge products.
ABSTRACT
PURPOSE: To report the clinical profile and visual impairment in various stages of neovascular glaucoma (NVG) at a tertiary eye center in East India. METHODS: The electronic medical records of the hospital database of patients with neovascular glaucoma seen between 2013 and 2020 were reviewed. Gonioscopic details were used to stratify patients into nonspecified NVG (Group 1), open-angle NVG (Group 2), and closed-angle NVG (Group 3). The clinical profile, angle features, cause of NVG, systemic associations, visual impairment, and blindness (defined as logarithm of the minimum angle of resolution, LogMar >1.3 at baseline and at final follow-up), and outcomes of medical/surgical interventions were compared between the three groups. RESULTS: Of 846 eyes of 810 patients with NVG (Group 1, n = 564 eyes, Group 2, n = 61 eyes, and Group 3, n = 220 eyes), at baseline, the blindness rates in Groups 3 and 2 were 90 and 75%, respectively. The time from a previous intervention to the onset of NVG ranged from 3 to 5 months, while the median duration of NVG was about 4-4.5 months (0.03-120 months). Multivariate regression identified a longer duration of NVG as the only variable associated with poor final visual acuity. CONCLUSION: Visual morbidity by NVG remains as high as 75-90% in developing countries, even with the availability of anti-VEGFs and after improved management/investigative at all stages.
