Mutual Interaction between Collectors and Frothers in Flotation

The behavior of a frother in flotation was investigated from the viewpoint of the mutual interaction between a collector and a frother. The floatability of galena and the interfacial tensions of the mercury-solution interface were measured using ethyl and amyl xanthates and normal alcohols containing 1～5 carbon atoms. The floatability test showed that butyl and amyl alcohols were favourable as a frother. The interfacial tension mesurements verified that alcohol molecules can adsorb on the mercurysurface only in coexistence with xanthate molecules in a solution. The degree of the coadsorption of alcohol molecule with xanthate molecule on mercury increases with increasing the number of carbon atoms in the alkyl chain of alcohol. It was clarified from the discussion of the infrared-spectroscopic study for the reagents that the value of ln(ν-ν₀) based on the shift of CH₃ stretching vibration was closely related to the degree of the coadsorption of a frother with a collector at the mineral-solution interface. Furthermore, the value of ln (ν－ν₀) was shown to be one of the measures indicating the choice of their proper combination

On the Critical Flotation Condition of a Sulfide Mineral Having Two Kinds of Positive Sites for the Anionic Collector and Depressant Adsorption

The critical flotation condition for the sulfide mineral having two kinds of positive sites was discussed from the viewpoint of the competitive adsorption of anionic collectors and depressants by means of statistical mechanics and chemical thermodynamics. On the basis of the statistical mechanics as to the collector-depressant equilibria, the familiar Barsky relation was derived for the double positive site mineral. The Barsky constant can be dependent on all of the collector and depressant adsorptions for each kind of reaction site on the mineral surface according to their adsorption property. In the chemical thermodynamics investigation, the chalcopyrite (CuFeS₂)-xanthatehydroxyl ion system was considered. The chemical affinities of the xanthate ion and the hydroxyl ion onto the positive sites of CuS and FeS, respectively, were calculated, using thermodynamical data for the system. Consequently, it was ascertained that the depressing action of the hydroxyl ion for chalcopyrite was mainly connected with the adsorption of the hydroxyl ion onto the positive site due to FeS, while the collecting mechanism of the xanthate ion for the same mineral is closely related to the adsorption of the xanthate ion onto the positive site due to CuS. The chalcopyrite (CuFeS₂)-xanthate-cyanide ion and hydroxyl ion system was also considered in a similar manner. The flotation-nonflotation condition of chalcopyrite was able to be determined by considering the xanthate adsorption on the positive site due to CuS and the cyanide ion adsoprtion on the one due to FeS

18. asırda "Hırkai şerif" ziyareti

Taha Toros Arşivi, Dosya No: 120-Saraylar. Not: Gazetenin "Tarihten Sahifeler" köşesinde yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Induction of liver-resident memory T cells and protection at liver-stage malaria by mRNA-containing lipid nanoparticles

Recent studies have suggested that CD8+ liver-resident memory T (TRM) cells are crucial in the protection against liver-stage malaria. We used liver-directed mRNA-containing lipid nanoparticles (mRNA-LNPs) to induce liver TRM cells in a murine model. Single-dose intravenous injections of ovalbumin mRNA-LNPs effectively induced antigen-specific cytotoxic T lymphocytes in a dose-dependent manner in the liver on day 7. TRM cells (CD8+ CD44hi CD62Llo CD69+ KLRG1-) were induced 5 weeks after immunization. To examine the protective efficacy, mice were intramuscularly immunized with two doses of circumsporozoite protein mRNA-LNPs at 3-week intervals and challenged with sporozoites of Plasmodium berghei ANKA. Sterile immunity was observed in some of the mice, and the other mice showed a delay in blood-stage development when compared with the control mice. mRNA-LNPs therefore induce memory CD8+ T cells that can protect against sporozoites during liver-stage malaria and may provide a basis for vaccines against the disease

A Carboxylic Acid from Ilex integra

Abstract: (12E,14E,17E)-11-Hydroxy-12,14,17-dodecatrienoic acid was isolated from the stems of Ilex integra and its structure was determined on the basis of the spectroscopic data of its methyl ester

Differential sensitivity to detect prosocial effects of 3,4‐methylenedioxymethamphetamine (MDMA) in different social approach paradigms in mice

Abstract A recreational drug, 3,4‐methylenedioxymethamphetamine (MDMA), has prosocial effects including increased sociability, enhancement of trust feelings, and empathy. Although several methods, such as the social interaction and three chamber tests, have been used, the neural mechanisms underlying the prosocial effects have not been well understood. In the present study, based on a social approach paradigm using a single‐chamber apparatus, we have developed two reproducible and simple social approach tests, SAT1 and SAT2, in ICR mice. In the SAT1, an unfamiliar mouse was set in a wire mesh cylinder cage that was placed in the center of a rectangular open field, while in the SAT2, an unfamiliar mouse was set in a wire mesh rectangular cage that was placed along a wall of a rectangular open field. Although MDMA treatment enhanced sociability in both SAT1 and SAT2, the ratio of high sociability mice was higher in the SAT2 than in the SAT1, indicating a differential sensitivity to detect the prosocial effects. Thus, we suggest that the SAT2 is a promising and suitable method to explore the neuronal mechanisms underlying the effects of MDMA

Pectolinarigenin Induces Antioxidant Enzymes through Nrf2/ARE Pathway in HepG2 Cells

Pectolinarigenin (PG) and its glycoside pectolinarin (PN) were reported to have various health beneficial functions such as anti-inflammatory and anti-carcinogenic activities. It has also been reported that PG and PN have radical scavenging ability as direct antioxidant activity. However, the indirect antioxidant activity of PG and PN by inducing antioxidant enzymes in hepatocytes is not fully understood yet. In this study, we investigated whether PG and PN increase expression of antioxidant enzymes through the nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated pathway in human hepatoma HepG2 cells and the liver of male ICR mice. PG, but not PN, induced antioxidant enzymes, namely heme oxigenase-1, NAD(P)H:quinone oxidoreductase 1, and aldo-keto reductase family 1 member B10, in HepG2 cells. As for the induction mechanism of these enzymes, PG-induced nuclear accumulation of Nrf2 increased antioxidant response element (ARE)-mediated transcriptional activity and suppressed degradation of Nrf2 through modification of Kelch-like EXH-associated protein 1. Oral administration of PG also induced nuclear accumulation Nrf2 and expression of antioxidant enzymes in the liver of mice. Therefore, PG, but not PN, exhibits the indirect antioxidant activity by inducing antioxidant enzymes through the Nrf2/ARE pathway and may protect liver from oxidative stress

Chemoenzymatically prepared konjac ceramide inhibits NGF-induced neurite outgrowth by a semaphorin 3A-like action

Dietary sphingolipids such as glucosylceramide (GlcCer) are potential nutritional factors associated with prevention of metabolic syndrome. Our current understanding is that dietary GlcCer is degraded to ceramide and further metabolized to sphingoid bases in the intestine. However, ceramide is only found in trace amounts in food plants and thus is frequently taken as GlcCer in a health supplement. In the present study, we successfully prepared konjac ceramide (kCer) using endoglycoceramidase I (EGCase I). Konjac, a plant tuber, is an enriched source of GlcCer (kGlcCer), and has been commercialized as a dietary supplement to improve dry skin and itching that are caused by a deficiency of epidermal ceramide. Nerve growth factor (NGF) produced by skin cells is one of the itch factors in the stratum corneum of the skin. Semaphorin 3A (Sema 3A) has been known to inhibit NGF-induced neurite outgrowth of epidermal nerve fibers. It is well known that the itch sensation is regulated by the balance between NGF and Sema 3A. In the present study, while kGlcCer did not show an in vitro inhibitory effect on NGF-induced neurite outgrowth of PC12 cells, kCer was demonstrated to inhibit a remarkable neurite outgrowth. In addition, the effect of kCer was similar to that of Sema 3A in cell morphological changes and neurite retractions, but different from C2-Ceramide. kCer showed a Sema 3A-like action, causing CRMP2 phosphorylation, which results in a collapse of neurite growth cones. Thus, it is expected that kCer is an advanced konjac ceramide material that may have neurite outgrowth-specific action to relieve uncontrolled and serious itching, in particular, from atopic eczema