Synthesis of nickel ferrite precursors from low grade nickel matte

Fine nickel ferrite precursors NiFe2（C204）3·6H2O were obtained via co-precipitation method with low grade nickel matte as the raw material. Thermodynamic analysis of NiClz-FeC12-（NH4）2C204-H20 system for precipitation identified that the theoretical optimum co-precipitation pH value is 2, and C2O2 has strong complexation with Ni2＋ and Fe2＋ ions. Based on these theoretical considerations, the effects of parameters on the precipitation rates and precursors size were investigated systematically. The results show that the optimum co-precipitation conditions are pH=2, temperature 45 ℃, 1.2 times theoretical amount of （NH4）2C204 dosage and 3% PEG400 addition. Under these conditions, the precipitation rates of Ni2＋ and Fe2＋ are both over 99.8%, with the precursors size of 1-2 urn. Furthermore, X-ray diffraction （XRD） and thermogravimetry-differential thermal analysis （TG-DTA） demonstrate that the precursors are single-phase solid solution, wherein the nickel/iron atoms are replaced by the iron/nickel atoms reciprocally.

Progress of ulcerative colitis patients during the COVID-19 pandemic

BACKGROUND We have previously demonstrated that the first wave of the coronavirus disease 2019(COVID-19)pandemic caused exacerbations in ulcerative colitis(UC)patients,probably through psychological and physical stress.However,successive waves of the COVID-19 pandemic continuously followed the first.The effects of this chronic stress on the disease condition in UC patients are of interest.AIM To clarify the effect of chronic stress from COVID-19 on disease condition in patients aggravated after the first wave.METHODS Our previous study investigated 289 consecutive UC outpatients treated in one center during March and April 2020,the period of the first wave of the COVID-19 pandemic.In this study,an identical group of 289 UC patients was evaluated using UC-disease activity index(UC-DAI),endoscopic mucosal appearance score,and Matts pathological grade scoring.RESULTS Of the 289 UC patients included in the study in 2020,10 patients dropped out as of 2021 and another 11 patients dropped out as of 2022,making three groups for 2020,2021 and 2022.No significant differences in characteristics were found among the three groups.UC-DAI scores had aggravated during the period of the first wave of the COVID-19 pandemic,but significantly recovered in 2021 and remained stable in 2022.Matts grade scores significantly recovered in 2021 from those in 2020 and remained stable in 2022.CONCLUSION Disease activity of UC patients recovered in 2021 and remained stable in 2022,aggravated by the stress of the first wave of COVID-19 in 2020 despite persistence of the pandemic.