RESUMEN
Nowadays, lithium-ion batteries are undoubtedly known as the most promising rechargeable batteries. However, these batteries face some big challenges, like not having enough energy and not lasting long enough, that should be addressed. Ternary Ni-rich Li[NixCoyMnz]O2 and Li[NixCoyAlz]O2 cathode materials stand as the ideal candidate for a cathode active material to achieve high capacity and energy density, low manufacturing cost, and high operating voltage. However, capacity gain from Ni enrichment is nullified by the concurrent fast capacity fading because of issues such as gas evolution, microcracks propagation and pulverization, phase transition, electrolyte decomposition, cation mixing, and dissolution of transition metals at high operating voltage, which hinders their commercialization. In order to tackle these problems, researchers conducted many strategies, including elemental doping, surface coating, and particle engineering. This review paper mainly talks about origins of problems and their mechanisms leading to electrochemical performance deterioration for Ni-rich cathode materials and modification approaches to address the problems.
RESUMEN
Beta-thalassemia major (TM) is the most prevalent genetic disease in Mazandaran Province. Currently, about 2,700 TM patients have been registered and are under treatment in the province. This study was undertaken to evaluate the survival of patients attending a dedicated clinic at the Boo Ali Sina Teaching Hospital, Sari, Iran, which was established in 1986. This survival analysis was conducted from July 2004 to September 2006. New deaths were updated in September 2006. A total of 1,010 medical records were reviewed. Place of residence, date of birth, first transfusion, initiation date of chelation, diagnosis of cardiac complications, diabetes and death were recorded. Compliance to treatment assessed by calculating the percentage of actual usage to prescribed iron chelator medicine and also by asking the attending nurse who was constantly present throughout the last 15 years. Validity of the opinion of the nurse was ascertained in a previous study. Kaplan-Meier statistics were used for analysis. The odds ratio (OR) and its 95% confidence interval (CI) for some risk factors of death were calculated. The survival rate of patients born before and after 1986 was also compared. Survival of both genders for birth cohort before and after 1986 was not statistically significant although the cohort of patients born after 1986 was better at 30 years old (68 vs. 80%). The survival of TM patients is improving but the prevalence of complications is high.
