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BACKGROUND: Tenecteplase is used as an alternative to alteplase and is considered noninferior for thrombolysis in acute ischemic stroke. OBJECTIVES: To compare the effectiveness and adverse effects of tenecteplase and alteplase in the real-world management of acute ischemic stroke. MATERIALS AND METHODS: In this retrospective observational study, we collected data from acute ischemic stroke patients admitted in six hospitals in West Bengal, India, and were thrombolysed with tenecteplase or alteplase between July 2021 and June 2022. Demographic data, baseline parameters, hospital course, and 3-month follow-up data were collected. The percentage of patients achieving a score of 0-2 in the modified Ranking scale at 3 months, rate of symptomatic intracranial hemorrhage, and all-cause mortality within 3 months were the main parameters of comparison between the two thrombolytic agents. RESULTS: A total of 162 patients were initially included in this study. Eight patients were excluded due to unavailability of follow-up data. Among the remaining patients, 71 patients received tenecteplase and 83 patients received alteplase. There was no statistically significant difference between tenecteplase and alteplase with respect to the percentage of patients achieving functional independence (modified Rankin scale score 0-2) at 3 months (53.5% vs. 60.2%, P = 0.706), rate of symptomatic intracranial hemorrhage (5.6% vs. 10.8%, P = 0.246), and all-cause mortality at 3 months (11.3% vs. 15.7%, P = 0.628). CONCLUSION: The effectiveness of tenecteplase is comparable to alteplase in the real-world management of acute ischemic stroke. Symptomatic intracranial hemorrhage and all-cause mortality rates are also similar in real-world practice.
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Spinel oxides represent an important class of cathode materials for Li-ion batteries. Two major variants of the spinel crystal structure are normal and inverse. The relative stability of normal and inverse ordering at different stages of lithiation has important consequences in lithium diffusivity, voltage, capacity retention and battery life. In this paper, we investigate the relative structural stability of normal and inverse structures of the 3d transition metal oxide spinels with first-principles DFT calculations. We have considered ternary spinel oxides LixM2O4 with M = Ti, V, Cr, Mn, Fe, Co and Ni in both lithiated (x = 1) and delithiated (x = 0) conditions. We find that for all lithiated spinels, the normal structure is preferred regardless of the metal. We observe that the normal structure for all these oxides has a lower size mismatch between octahedral cations compared to the inverse structure. With delithiation, many of the oxides undergo a change in stability with vanadium in particular, showing a tendency to occupy tetrahedral sites. We find that in the delithiated oxide, only vanadium ions can access a +5 oxidation state which prefers tetrahedral coordination. We have also calculated the average voltage of lithiation for these spinels. The calculated voltages agree well with the previously measured and calculated values, wherever available. For the yet to be characterized spinels, our calculation provides voltage values which can motivate further experimental attention. Lastly, we observe that all the normal spinel oxides of the 3d transition metal series have a driving force for a transformation to the non-spinel structure upon delithiation.
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Intercalation compounds, used as electrodes in Li-ion batteries, are a fascinating class of materials that exhibit a wide variety of electronic, crystallographic, thermodynamic, and kinetic properties. With open structures that allow for the easy insertion and removal of Li ions, the properties of these materials strongly depend on the interplay of the host chemistry and crystal structure, the Li concentration, and electrode particle morphology. The large variations in Li concentration within electrodes during each charge and discharge cycle of a Li battery are often accompanied by phase transformations. These transformations include order-disorder transitions, two-phase reactions that require the passage of an interface through the electrode particles, and structural phase transitions, in which the host undergoes a crystallographic change. Although the chemistry of an electrode material determines the voltage range in which it is electrochemically active, the crystal structure of the compound often plays a crucial role in determining the shape of the voltage profile as a function of Li concentration. While the relationship between the voltage profile and crystal structure of transition metal oxide and sulfide intercalation compounds is well characterized, far less is known about the kinetic behavior of these materials. For example, because these processes are especially difficult to isolate experimentally, solid-state Li diffusion, phase transformation mechanisms, and interface reactions remain poorly understood. In this respect, first-principles statistical mechanical approaches can elucidate the effect of chemistry and crystal structure on kinetic properties. In this Account, we review the key factors that govern Li diffusion in intercalation compounds and illustrate how the complexity of Li diffusion mechanisms correlates with the crystal structure of the compound. A variety of important diffusion mechanisms and associated migration barriers are sensitive to the overall Li concentration, resulting in diffusion coefficients that can vary by several orders of magnitude with changes in the lithium content. Vacancy clusters, groupings of vacancies within the crystal lattice, provide a common mechanism that mediates Li diffusion in important intercalation compounds. This mechanism emerges from specific crystallographic features of the host and results in a strong decrease of the Li diffusion coefficient as Li is added to an already Li rich host. Other crystallographic and electronic factors, such as the proximity of transition metal ions to activated states of hops and the occurrence of electronically induced distortions, can result in a strong dependence of the Li mobility on the overall Li concentration. The insights obtained from fundamental studies of ionic diffusion in electrode materials will be instrumental for physical chemists, chemical engineers, synthetic chemists, and materials and device designers who are developing these technologies.