Improved flotation performance of hematite fines using citric acid as a dispersant

In this study, citric acid was used as a dispersant to improve the flotation performance of hematite fines. The effect and mechanism of citric acid on the reverse flotation of hematite fines were investigated by flotation tests, sedimentation experiments, scanning electron microscopy（SEM）, zeta-potential measurements, and X-ray photoelectron spectroscopy（XPS）. The results of SEM analysis and flotation tests reveal that a strong heterocoagulation in the form of slime coating or coagulation in hematite fine slurry affects the beneficiation of hematite ores by froth flotation. The addition of a small amount of citric acid（less than 300 g/t） favorably affects the reverse flotation of hematite fines by improving particle dispersion. The results of sedimentation experiments, zeta-potential measurements, and XPS measurements demonstrate that citric acid adsorbs onto hematite and quartz surfaces via hydrogen bonding, thereby reducing the zeta potentials of mineral surfaces, strengthening the electrical double-layer repulsion between mineral particles, and dispersing the pulp particles.

Effectiveness and Safety of Moxibustion for Poststroke Insomnia:A Systematic Review and Meta-analysis

Objective:This study aimed to systematically evaluate the clinical efficiency and safety of moxibustion for the treatment of poststroke insomnia(PSI).Methods:We searched PubMed,the Cochrane Library,Embase,China National Knowledge Infrastructure(CNKI),Wanfang Data Knowledge Service platform(Wanfang Data),Chinese Scientific Journal Database(VIP),and clinical rial for trandomized controlled trials on moxibustion as a treatment for PSI,including results from the creation of all databases until December 12,2020.The functional languages used were Chinese and English.Two reviewers independently performed the literature search,data extraction,and quality evaluation.The primary and secondary outcome measures were the effective rate and adverse events,respectively.The meta-analysis was carried out using RevMan5.4 software and Stata15.Results:Of the 11 trials,996 patients in China's Mainland were included.Compared to the control group,the combination of single moxibustion therapy or moxibustion combined with acupuncture in the treatment of DN could reduce the sleep quality score(SQS)(mean difference[MD]=-0.50,95%confidence interval[CI][-0.89,-0.11],Z=2.51,P=0.01),time to falling asleep score(MD=-0.39,95%CI[-0.49,-0.29],Z=7.79,P<0.00001),sleep time score(MD=-0.34,95%CI[-0.59,-0.09],Z=2.64,P=0.008),sleep efficiency score(MD=-0.30,95%CI[-0.52,-0.08],Z=2.69,P=0.007),sleep disorder score(MD=-0.29,95%CI[-0.49,-0.09],Z=2.85,P=0.004),daily function disturbance score(MD=-0.54,95%CI[-0.82,-0.26],Z=3.78,P=0.0002),Pittsburgh Sleep Quality Index aggregate score(MD=-2.30,95%CI[-2.97,-1.63],Z=6.71,P<0.00001),SPIEGEL aggregate score(MD=-7.62,95%CI[-8.12,-7.12],Z=29.75,P<0.00001),and stroke-specific quality of life aggregate score(MD=12.68,95%CI[0.92,24.44],Z=2.11,P=0.03).Conclusion:This study indicates that moxibustion contributes to the treatment of PSI.Nevertheless,more extensive trials are required to validate the results due to the small sample sizes,few reports on adverse effects,and high risk of bias in the included studies.