Fundamental Studies on the Collection of Sulphide Minerals with Xanthic Acids. II : Reactions of Formation of Heavy Metal Complexes with Xanthic Acids

Spectrophotometric studies were made on the reactions of formation of Pb (II), Ni (II) and Co (II) complexes with ethyl xanthic acid and Co (II) complexes with methyl, n-propyl, n-butyl xanthic acids in acetone-water (1 : 1) solution. The effects of various factors affecting the reactions of formation of these complexes were studied and their compositions and formation constants were evaluated. Xanthic acid reacts with Pb (II), Ni (II) and Co (II) to form only one species of complex, respectively. The composition of Pb(II) complex with ethyl xanthic acid can be represented as 1 : 2, and those of all other complexes as 1 : 3. It may be considered that these complexes form four-membered chelates with two bidentate ligands. The formation constants of PbX_2 and NiX_3- complexes in acetone-water (1 : 1) solution were determined to be 1.83×10^8 and 0.90×10^, respectively, at 25℃ and for an ionic strength of 0.5. The formation constants of Co (II) complexes with methyl, ethyl, n-propyl and n-butyl xanthic acids were determined to be 1.02×10^, 0.98×10^, 3.40×10^ and 4.53×10^ respectively. It was found that the logarithmic values of the formation constants of their complexes varied linearly with the values of pKa of xanthic acids. Further it was pointed out that the important relation existed between the effectiveness of xanthic acids as collectors in flotation and the values of the formation constants of their heavy metal complexes

Studies on the Flotation of Molybdenite. I : Flotation of Molybdenite Ore Containing Clayey Gangue

Some points to be considered in the flotation of molybdenite containing clayey gangue were investigated, and based on the results obtained, the method of flotation operation was examined at the Daito mine, Shimane Prefecture. In the rougher flotation of molybdenite ore, high concentrate grade and recovery can be obtained by selecting the proper ratio of silica to soda and suitable concentration of sodium silicate to be added. Sodium silicate having the ratio of silica to soda 2 : 1 shows the most effective depressing action on gangue minerals. The minimum content of SiO_2 in the froth product is obtained when the conditioning time after adding sodium silicate is 10-20 minutes. It is preferable to use sodium hydroxide instead of lime to regulate the pH value of the pulp containing much primary slime. On the contraty, lime is effective for the flotation of molybdenite ore containing no primary slime. Though it is usual to use oily collectors as collecting agents for molybdenite, quantities to be added to obtain good flotation results are unexpectedly large. In some cases molybdenite can be recovered at high rates of recovery by using xanthate with oily collector, but we should be cautious of using much xanthate. However, a good flotation result cannot be expected with xanthate only. At the Daito mine, the flotation results have been improved by modifications of flotation methods : slime is treated by a separate flotation circuit and the froths are returned to the main circuit. Sodium hydroxide is used to regulate the pH value of the pulp. Thus, no difficulty has been experienced in producing a molybdenite concentrate assaying 86.3-87.4% MoS_2 with a recovery of 95.5-97.9% from a flotation feed assaying 1.06-1.13% MoS_2

Oral Exposure to Polystyrene Microplastics of Mice on a Normal or High-Fat Diet and Intestinal and Metabolic Outcomes

マイクロプラスチックの経口摂取が高脂肪食条件下での代謝障害を悪化させる. 京都大学プレスリリース. 2023-02-24.[Background:] Microplastics (MPs) are small particles of plastic (≤ 5mm in diameter). In recent years, oral exposure to MPs in living organisms has been a cause of concern. Leaky gut syndrome (LGS), associated with a high-fat diet (HFD) in mice, can increase the entry of foreign substances into the body through the intestinal mucosa. [Objectives:] We aimed to evaluate the pathophysiology of intestinal outcomes associated with consuming a high-fat diet and simultaneous intake of MPs, focusing on endocrine and metabolic systems. [Methods:] C57BL6/J mice were fed a normal diet (ND) or HFD with or without polystyrene MP for 4 wk to investigate differences in glucose tolerance, intestinal permeability, gut microbiota, as well as metabolites in serum, feces, and liver. [Results:] In comparison with HFD mice, mice fed the HFD with MPs had higher blood glucose, serum lipid concentrations, and nonalcoholic fatty liver disease (NAFLD) activity scores. Permeability and goblet cell count of the small intestine (SI) in HFD-fed mice were higher and lower, respectively, than in ND-fed mice. There was no obvious difference in the number of inflammatory cells in the SI lamina propria between mice fed the ND and mice fed the ND with MP, but there were more inflammatory cells and fewer anti-inflammatory cells in mice fed the HFD with MPs in comparison with mice fed the HFD without MPs. The expression of genes related to inflammation, long-chain fatty acid transporter, and Na⁺/glucose cotransporter was significantly higher in mice fed the HFD with MPs than in mice fed the HFD without MPs. Furthermore, the genus Desulfovibrio was significantly more abundant in the intestines of mice fed the HFD with MPs in comparison with mice fed the HFD without MPs. Muc2 gene expression was decreased when palmitic acid and microplastics were added to the murine intestinal epithelial cell line MODE-K cells, and Muc2 gene expression was increased when IL-22 was added. [Discussion:] Our findings suggest that in this study, MP induced metabolic disturbances, such as diabetes and NAFLD, only in mice fed a high-fat diet. These findings suggest that LGS might have been triggered by HFD, causing MPs to be deposited in the intestinal mucosa, resulting in inflammation of the intestinal mucosal intrinsic layer and thereby altering nutrient absorption. These results highlight the need for reducing oral exposure to MPs through remedial environmental measures to improve metabolic disturbance under high-fat diet conditions

千葉県君津市川谷地域に露出する中部更新統柿ノ木台層から産出する冷湧水化石群集: その時空分布と共産する自生炭酸塩

金沢大学国際基幹教育院 GS教育系冷湧水性群集が房総半島の中部更新統柿ノ木台層の陸棚相から産出する．群集は，化学合成二枚貝類から排他的になり，著しく13Cに枯渇した自生炭酸塩と共産することから，AOM（嫌気的メタン酸化）に依存していたと考えられる．自生炭酸塩は巣穴壁面と巣穴周囲の堆積物中に沈殿し，巣穴からスナモグリ類の爪化石と糞化石が産出することから，これらはスナモグリ類の巣穴であると考えられる．スナモグリ類はメタン生成帯まで巣穴を堀り，海水を巣穴深部へ供給し，AOMを活性化させることによって巣穴中の硫化水素イオン濃度を上昇させた．溶存酸素濃度が高い巣穴浅部では，硫黄酸化菌が繁茂し，スナモグリ類の食糧となった．巣穴深部では，浮遊する生物源炭酸塩などを核とした針状アラゴナイトが重力方向に沈下して炭酸塩ジオペタル状構造を形成し，巣穴周囲の堆積物中では，リン酸イオン濃度の上昇により高Mgカルサイトが，また硫酸イオンの枯渇によりドロマイトが沈殿した．Cold-seep-dependent molluscan assemblages occur in the outer-shelf facies of the middle Pleistocene Kakinokidai Formation of the Kazusa Group, a forearc basin-fill sequence on the Pacific side of central Japan, in strata corresponding to the interval 707.6-667.0 ka. The assemblages consist exclusively of chemosymbiotic bivalves (lucinids, thyasirids, and solemyids) and are associated with 13C-depleted authigenic carbonates (δ13C = −61.60‰ to −10.96‰ VPDB), which suggest that their main carbon source was anaerobic oxidation of methane (AOM). Authigenic carbonate precipitates are common on burrow walls (mainly acicular aragonite) and the surrounding sediments (mainly micritic high-Mg calcite and dolomite). The burrows are cylindrical, 1.5-3.0 cm in diameter, and >1 m long. Callianassid claws and the trace fossil Palaxius (probable callianassid fecal pellets) in the burrow carbonates suggest that the burrows were produced by sediment-dwelling callianassid decapods.\nWe propose the following formation mechanism of burrows and their related authigenic carbonates. Firstly, callianassids produced deep burrows, penetrating the AOM zone and reaching the methanogenic zone. Methane then seeped into the burrows and AOM occurred in its deeper parts, promoted by a supply of seawater via callianassid activity, resulting in an increase in the concentration of hydrogen sulfide ions. Thiobacteria flourished in the shallower parts of the burrows, which were enriched in dissolved oxygen, and provided a source of food for the callianassids. In the deeper parts of the burrows, acicular aragonite precipitated around suspended carbonate nuclei and sank to the bottoms of the burrows, forming geopetal-like carbonate structures. In the surrounding sediment, high-Mg calcite precipitated in response to an increase in the concentration of phosphate ions (due to the decomposition of organic matter), and dolomite precipitated in response to decreasing concentrations of sulfate ions (caused by active AOM)

緑茶カフェインの各種二次乾燥工程による影響(B. 生活科学)

緑茶の二次乾燥工程において, マイクロ波, セラミックボール混合, 遠赤外線などの方法を組み合わせ, 各種温度条件下の製品を作製し, それらの水分含量およびカフェイン量について検討した。その結果水分の乾燥はかなり能率よく行なわれ, その際に殆んどの製品に於てカフェインの損失は見られなかった。これらの方法は従来の熱風乾燥法に比べ熱効率がよく短時間処理も可能で, 将来有望なものであることがわかった。Secondary heating process of green tea manufacture was carried out by using microwave, ceramic ball and far I. R. -heating apparatus, instead of conventional hot-air device. The processed green teas lose moisture effectively, while the marked losses of the caffeine contents were not obseved. The new heating apparatus was beneficial for controlling the temperature of the heating process and saving time for the process

Fundamental Studies on the Collection of Sulphide Minerals with Xanthic Acids. I : On the Dissociation and Decomposition of Xanthic Aicds

The dissociation constants of xanthic acids and the rates of decomposition of xanthic ions in acidified aqueous solutions were determined by spectrophotometric measurements. It was found that xanthic ion and xanthic acid are virtually in equilibrium, and that the dissociation constants of methyl-, ethyl, propyl-, butyl-, amyl-, iso-propyl-, and iso-butylxanthic acids are respectively 3.4×10^, 2.9×10^, 2.5×10^, 2.3×10^, 1.9×10^, 2.0×10^ and 1.4×10^ at 25℃ and the ionic strength of 0. The instability of xanthic ion in acidic range is due to the bimoleucular decomposition of xanthic ion and hydrogen ion. The rate constants of decomposition of methyl-, ethyl-, propyl-, amyl-, isopropyl-, and iso-butylxanthic ions are respectively 233, 226, 214, 209, 211. 207, and 202 mole^min^ at 25℃ and the ionic strength of 0. The dissociation constants of these xanthic acids and the rate constants of these xanthic ions decreased the increase in carbon numbers of these alkyl groups, and iso-isomer has smaller values of these constants than those of normal ones. Furthermore, it was shown that the peak of absorption spectrum of xanthic ion is at 301 mμ and that of xanthic acid at 270 mμ