Search

Gas dispersion characteristics are of significant importance in froth flotation. Studies show that cyclonic static microbubble flotation column (FCSMC) is an efficient device to recover fine minerals. In the present study, the gas holdup distribution and the mean gas holdup in a laboratory gas-liquid FCSMC are first quantitatively measured by electrical resistance tomography (ERT). Different flowrates of gas and liquid are considered. Performed experiments show that when the air flowrate increases from 1.1 L/min to 2.3 L/min, the mean gas holdups on measured planes increase to about 4 ~ 5 times the original value. The gas dispersion along the radial direction is poor, which is dense in the center and rare in the periphery. This uneven bubble distribution aggravates as the amount of the supplying air increases. As the circulating liquid flux increases, the corresponding measured gas holdup gradually decreases and the bubble shrinks to the center along the radial direction. When the liquid flux increases from 1.5 m3/h to 1.8 m3/h, the averaged decline of the mean gas holdup on measured planes reduces to 54 ~ 65% of the original value. Finally, it is validated that the sieve plate packing effectively reduces non-uniform radial and axial distributions of the gas holdup. The obtained results might lead to more effective operating of FCSMC, provide a reference for further numerical study and ERT application in other complicated devices. [ABSTRACT FROM AUTHOR]

Microglial activation-induced neuroinflammation is closely associated with the development of Parkinson disease (PD). Macroautophagy/autophagy regulates many biological processes, but the role of autophagy in microglial activation during PD development remains largely unclear. In this study, we showed that deletion of microglial Atg5 caused PD-like symptoms in mice, characterized by impairment in motor coordination and cognitive learning, loss of tyrosine hydroxylase (TH) neurons, enhancement of neuroinflammation and reduction in dopamine levels in the striatum. Mechanistically, we found that inhibition of autophagy led to NLRP3 (NLR family pyrin domain containing 3) inflammasome activation via PDE10A (phosphodiesterase 10A)–cyclic adenosine monophosphate (cAMP) signaling in microglia, and the sequential upregulation of downstream IL1B/IL-1β in turn increased the expression of MIF (macrophage migration inhibitory factor [glycosylation-inhibiting factor]), a pro-inflammatory cytokine. Inhibition of NLRP3 inflammasome activation by administration of MCC950, a specific inhibitor for NLRP3, decreased MIF expression and neuroinflammatory levels, and rescued the loss of TH neurons in the substantial nigra (SN). Interestingly, we found that serum MIF levels in PD patients were significantly elevated. Taken together, our results reveal an important role of autophagy in microglial activation-driven PD-like symptoms, thus providing potential targets for the clinical treatment of PD. Abbreviations: ATG: autophagy related; cAMP: cyclic adenosine monophosphate; cKO: conditional knockout; NOS2/INOS: nitric oxide synthase 2, inducible; IL1B: interleukin 1 beta; ITGAM/CD-11b: integrin alpha M/cluster of differentiation molecule 11B; MAP1LC3: microtubule-associated protein 1 light chain 3; MIF: macrophage migration inhibitory factor (glycosylation-inhibiting factor); NLRP3: NLR family pyrin domain containing 3; PBS: phosphate-buffered saline; PD: parkinson disease; PDE10A: phosphodiesterase 10A; SN: substantial nigra; TH: tyrosine hydroxylase; TNF: tumor necrosis factor; WT: wild type. [ABSTRACT FROM AUTHOR]

The effect of single frothers and their blends on bubble size, froth stability, and unburned carbon (UC) flotation performance was studied. Methyl isobutyl carbinol that produces smaller bubbles is efficient in floating ultrafine particles and producing concentrate. DF-250 that gives higher froth stability is effective for recovering coarse particles and improving recovery. The presence of DF-250 in the blend increases bubble size and significantly enhances froth stability, and hence the optimal flotation performance is achieved with 75% DF-250. It indicates that the frother giving high froth stability is better in UC flotation due to the little effect of UC on froth stability. [ABSTRACT FROM AUTHOR]

The neurotoxicity of ziram is largely unknown. In this study, we investigated the direct inhibitions of ziram on rat neurosteroid synthetic and metabolizing enzymes, 5α-reductase 1 (SRD5A1), 3α-hydroxysteroid dehydrogenase (AKR1C14), and retinol dehydrogenase 2 (RDH2). Rat SRD5A1, AKR1C14, and RDH2 were cloned and transiently expressed in COS1 cells, and the effects of ziram on these enzymes were measured. Ziram inhibited rat SRD5A1 and AKR1C14 with IC50values of 1.556 ± 0.078 and 1.017 ± 0.072 μM, respectively, when 1000 nM steroid substrates were used. Ziram weakly inhibited RDH2 at 100 μM, when androstanediol (1000 nM) was used. Ziram competitively inhibited SRD5A1 and non-competitively inhibited AKR1C14 when steroid substrates were used. Docking study showed that ziram bound to NADPH-binding pocket of AKR1C14. In conclusion, our results demonstrated that ziram inhibited SRD5A1 and AKR1C14 activities, thus possibly interfering with neurosteroid production in rats. [ABSTRACT FROM PUBLISHER]

Leukemia inhibitory factor (LIF) has many physiological roles. However, its effects on Leydig cell development are still unclear. Rat immature and adult Leydig cells were cultured with different concentrations of LIF alone or in combination with luteinizing hormone (LH) for 24 h. LIF (1 and 10 ng/ml) significantly increased androgen production in immature Leydig cells, but had no effects on testosterone production in adult Leydig cells. Further studies revealed that LIF dose-dependently increasedStarandHsd17b3expression levels in immature Leydig cells. Gene microarray revealed that the upregulation of anti-oxidative genes andStarmight contribute to LIF-induced androgen production. In conclusion, LIF has stimulatory effects on androgen production in rat immature Leydig cells. [ABSTRACT FROM PUBLISHER]

Butylated hydroxyanisole (BHA) is a synthetic antioxidant used for food preservation. Whether BHA affects testosterone biosynthesis is still unclear. The effects of BHA on the steroidogenesis in rat immature Leydig cells were investigated. Rat immature Leydig cells were isolated from 35-old-day rats and cultured with BHA (50 μM) for 3 h in combination with 22R-OH-cholesterol, pregnenolone, progesterone, androstenedione, testosterone or dihydrotestosterone, and the concentrations of 5α-androstanediol and testosterone in the media were measured. Leydig cells were cultured with BHA (0.05–50 μM) for 3 h. Q-PCR was used to measure the mRNA levels of following genes:Lhcgr,Scarb1,Star,Cyp11a1,Hsd3b1,Cyp17a1,Hsd17b3,Srd5a1andAkr1c14. The testis microsomes were prepared to detect the direct action of BHA on 3β-hydroxysteroid dehydrogenase 1 (HSD3B1), 17α-hydroxylase (CYP17A1) and 17β-hydroxysteroid dehydrogenase 3 activities. In Leydig cells, BHA (50 μM) significantly inhibited LH- and 8Br-cAMP-mediated androgen production. BHA directly inhibited rat testis CYP17A1 and HSD3B1 activities. At 50 μM, it also reduced the expression levels ofHsd17b3andSrd5a1and their protein levels. In conclusion, BHA directly inhibits the activities of CYP17A1 and HSD3B1, and the expression levels ofHsd17b3andSrd5a1, leading to the lower production of androgen in Leydig cells. [ABSTRACT FROM PUBLISHER]