Search

Lithium (Li)-bearing clays have become new types of Li resources, and it is found that the evolution of the mineral structure in Li-bearing clay greatly restricts the extraction of Li. Herein, a Li-bearing clay from Guizhou Province, China, was studied using in situ thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) (evolved gases), 27Al and 1H magic-angle spinning nuclear magnetic resonance (MAS NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results showed that the Li-bearing clay contained illite, chlorite, kaolinite, pyrite, and anatase. The dehydroxylation reaction of the clay minerals occurred at 450 °C. CH2, CH4, C3H4, C6H5, and C8H9 evolved during the roasting process. The AlO4(OH)2 octahedra transformed to AlO4 tetrahedra due to the reaction between the reductive gases and the residual O in AlO5. The effect of dehydroxylation on the structural stability of different clay minerals differed. After dehydroxylation, kaolinite became amorphous, chlorite reacted with 20% H2SO4, and illite remained stable during the roasting-H2SO4 leaching process. The Li-leaching efficiency increased significantly after dehydroxylation and decreased sharply with the formation of mullite. [ABSTRACT FROM AUTHOR]

Ampelopsis grossedentata leaves are highly rich in dihydromyricetin. They have been used to make tea in China for centuries. Dihydromyricetin has many potential applications in foods and medicine. This are because it has five phenolic hydroxyl groups. However, the hydroxylases involving the biosynthesis of dihydromyricetin have not been identified and characterized. In this study, a series of hydroxylases genes, including flavanone 3-hydroxylase (F3H), flavonoid 3′-hydroxylase (F3′H), flavonoid 3′,5′-hydroxylase (F3′5′H), and cytochrome P450 reductase (CPR), were identified after RNA sequencing. The full-length CDSs of AgF3H, AgF3′H, AgF3′5′H, and AgCPR genes were amplified from the cDNA library of leaves. The aforementioned enzymes were expressed and verified in Saccharomyces cerevisiae. Through the substrate specificity assay, the functional AgF3′H, AgF3′5′H, and AgCPR in A. grossedentata were identified. The dihydromyricetin hydroxylation process in A. grossedentata was successfully identified. We found that substantial carbon flux occurred through the Naringenin (NAR)–Eriodictyol (ERI)–Dihydroquercetin (DHQ)–Dihydromyricetin (DHM) and NAR–Dihydrokaempferol (DHK)–DHQ–DHM pathways. This study provides some reference for the development and utilization of the germplasm resources and molecular breeding of A. grossedentata. [ABSTRACT FROM AUTHOR]

The thermal characteristic behaviors of two kaolinite samples selected from Qingshuihe region in Inner Mongolia in China were studied through thermogravimetry, derivative thermogravimetry, and differential scanning calorimetry (TG–DTG–DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The activation energies of dehydroxylation for the two kaolinite samples (determined as Kaol-1 and Kaol-2) were calculated based on KAS and FWO methods. The XRD results indicated that Kaol-1 and Kaol-2 both were determined as kaolinite, and a small amount of quartz, but the Kaol-2 presented many amorphous organic matters. The TG–DSC results displayed the adsorbed water desorption and dehydroxylation with the temperature increased from 200 to 1100 °C. The dehydroxylation is followed as the intensities decrease in the bands at 3690 cm−1, 3620 cm−1 and 914.0 cm−1 attributing to the stretching mode of inner surface hydroxyls, and which disappeared when the temperature reached at 600 °C. The endothermic peak temperature of dehydroxylation for Kaol-2 presented higher than that of Kaol-1, which may be attributed to present of amorphous organic matter and was in agreement with the XRD data. The maximum endothermic temperature of dehydroxylation increased both for Kaol-1 and Kaol-2 with the increase in heating rate, which was attributed to more sufficient decomposition as the decrease in heating rate. The thermal kinetic analysis indicated that the dehydroxylation reaction of Kaol-1 should be a single kinetic mechanism, but the E of Kaol-2 decreased as α increasing from 0.2 to 0.5 and then gradually increased with the increase of α. The average E of dehydroxylation for Kaol-2 both was lower than that of Kaol-1 based on Kissenger–Akahira–Sunose and Flynn–Wall–Ozawa methods, which was attributed to the relatively higher organic carbon content in Kaol-2. [ABSTRACT FROM AUTHOR]

The presence and formation of hydroxy-interlayered minerals in the Holocene paleosol at the Wugong profile on the southernmost Chinese Loess Plateau were investigated by examining the < 1 μm and 1–2 μm clay fractions of the 50–150 cm horizon by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Prior to the analyses free Al and Fe phases were removed by dithionite-citric-bicarbonate (DCB) extraction. XRD patterns were obtained with air-dried, Mg-saturated, Mg-saturated with glycerol solvation (Mg-glycerol) and K-saturated and heated at 110, 250, 350, 450 and 550 °C samples both before and after hydroxy-interlayered materials removal by sodium citrate extraction. The absorption bands at 3699 and 3430 cm − 1 in the FTIR spectra of both sub-fractions indicated the presence of hydroxy-interlayered minerals. The K-saturated and heated XRD patterns confirmed this by the progressive collapse of the 1.4 nm reflection to a 1.0 nm reflection. After removal of the hydroxy-interlayered materials no obvious increase of the relative XRD intensity of the 1.8 nm reflection in Mg-glycerol pattern was observed and the 1.4 nm reflection exhibited a stronger collapse to 1.0 nm after K-saturation and increasing temperature treatment. This indicated that the hydroxy-interlayered minerals in the Holocene paleosol were mainly composed of hydroxyl-interlayer vermiculite. The hydroxyl-interlayer vermiculite was formed by the polymerization of Al/Fe-hydroxy materials within the interlayer space of vermiculite. Shoulder-like reflection at 1.2 nm in the K-550 °C pattern of the 1–2 μm fraction indicated a higher degree of Al/Fe-hydroxylation in the coarse fraction than in the fine fraction, which was consistent with the lower extractable Al and Fe in the coarse fraction. The reflection at 1.38 nm in the K-550 °C pattern could be interpreted as pedogenic chlorite. Thus, transformation of vermiculite into hydroxy-interlayered vermiculite and finally into a chlorite-like mineral (pedogenic chlorite) has occurred in the Holocene paleosol on the southernmost Chinese Loess Plateau. [ABSTRACT FROM AUTHOR]

Despite extensive researches, many aspects of the structural transformation that occur in illite on heating remain unclear. This study concentrates on samples from a mine located in Wenzhou, Zhejiang Province, China to supplement data obtained by previous investigators. In situ high temperature X-ray diffraction (HTXRD), infrared spectroscopy (IR), field emission scanning electron microscope (FESEM) and electron microprobe (EMP) analysis were used to record the characterization of the raw material. XRD pattern showed the illite sample was primarily in 2M 1 polytype. The phase transition from illite into dehydroxylated phase started at about 525 °C in static air and at about 550 °C in vacuum, and from dehydroxylated phase into mullite occurred at above 1100 °C. These lattice parameters of illite (RT – 1100 °C) and mullite (1125–1150 °C) both in static air and in vacuum were refined. The variations of illite lattice parameters with temperature (°C) were therefore well described. Thermal expansion coefficients of illite (RT – 1100 °C) were determined. In situ high temperature X-ray diffraction study revealed four stages during heating: expansion, dehydroxylation, post-dehydroxylation and mullite stages. [ABSTRACT FROM AUTHOR]

The thermal behavior of coal gangue selected from Zhungeer, Inner Mongolia Autonomous Region of China, was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry (TG), derivative thermogravimetry (DTG), and scanning electron microscope (SEM). The XRD data indicated that the mineral compositions of the coal gangue were kaolinite, boehmite, and quartz. The coal-gangue sample was considered as belonging to a typical mixture of kaolinite and boehmite. The XRD and FT-IR spectra clearly showed that the structural changes and dehydroxylation of coal gangue occurred with increased temperature from 100 to 900 °C. The reaction activity of coal gangue could be effectively improved by calcination. The calcined coal gangue contained considerable active amorphous AlO and SiO and had significant loss on ignition. The optimum activation temperature range of coal gangue was from 600 to 700 °C. The dissolution contents of SiO and AlO were 92.31 and 64.44 %, respectively, when the calcination temperature at 700 °C. [ABSTRACT FROM AUTHOR]

Seven polybrominated diphenyl ethers (PBDEs) and eleven hydroxylated PBDEs (OH-PBDEs) were selected to investigate their contamination status in 32 female serum samples from Dalian, China. These studied PBDEs and OH-PBDEs were found in most of the serum samples with the concentrations of ΣPBDEs and ΣOH-PBDEs ranging from 1.07 to 38.7ng/g lipid (median: 5.56ng/g lipid) and from 0.011 to 0.436ng/g lipid (median: 0.069ng/g lipid), respectively. More impressively, BDE-47 and OH-BDE-47 were the predominant congeners in female serum, accounting for 52% of ΣPBDEs and 46% of ΣOH-PBDEs, respectively. Correspondence analysis indicated that significant (p<0.05) positive correlations were observed between BDE-47 and its metabolites such as 6-OH-BDE-47, 3-OH-BDE-47 and 4'-OH-BDE-49. In addition, the positive significant (p<0.05) correlation was shown between ∑PBDEs and lipid contents but between concentrations of ∑PBDEs and ages or BMIs, as well as for ∑OH-PBDEs. [ABSTRACT FROM AUTHOR]

Anthocyanins and flavonols are important flavonoid metabolites in grapes, making a dominant contribution to the color, the mouth feel and even the flavor of grapes and wines. The accumulation of these flavonoids in grapes is greatly influenced by a many, diverse but interacting factors, of which variety and climate are among the most important ones. In the present study, the anthocyanin and flavonol profiles of four grape varieties ( Vitis vinifera L.), Cabernet Sauvignon, Carmenere, Syrah and Merlot, from five major wine regions in China were examined for two consecutive years (2006 and 2007). The results showed that the total anthocyanin content of the berry skins in these cultivars tended to increase from east to west in China, yet the proportion of the acylated anthocyanins displayed the opposite trend. It seemed possible that the western grape regions, with their high altitude and low annual rainfall, had an advantage in producing high level of anthocyanins. In addition, a high proportion of trihydroxylated flavonols were always found in the western region grapes, whereas dihydroxylated flavonols were more prominent in the lower altitude eastern regions. This suggested that the relative amounts of these flavonoid compounds may depend on their corresponding cultivar characteristics, while the amounts are more affected by the environmental factors where they were growing. [ABSTRACT FROM AUTHOR]

Highlights: [•] Presence of polybrominated compounds in bivalves from Beijing markets was studied. [•] Levels of PBDEs in this study were higher than those in Baltic blue mussels. [•] Levels of OH- and MeO-PBDEs in this study were lower than in Baltic blue mussels. [•] Polybrominated compounds showed significant seasonal variations in blue mussels. [•] Acidic components displayed different seasonal variations from neutral components. [Copyright &y& Elsevier]

Abstract: Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) along with methoxylated polybrominated diphenyl ethers (MeO-PBDEs) have been frequently identified as natural compounds in marine environment and also assumed as metabolites of PBDEs. In the present study, nine OH-PBDE, nine MeO-PBDE and 10 PBDE congeners were studied in the sewage sludge collected from 36 municipal wastewater treatment plants (WWTPs) in 27 cities of China. The results suggest that OH-PBDEs and PBDEs are ubiquitous in sewage sludge in China, however, methoxylated PBDEs were not detectable. Composition profiles of detected OH-PBDE congeners were different depending on the sampling location. ΣOH-PBDEs in WWTPs sludge ranged from 0.04 to 2.24ngg−1 dry weight (mean: 0.35ngg−1 dry weight). The total amount of the two most prominent congeners (6-OH-BDE-47+2′-OH-BDE-68) accounted for about 53.3–100% of the sum of all six identified congeners. A significant linear relationship was found between 6-OH-BDE-47 and 2′-OH-BDE-68. A distinct geographical distribution of ΣOH-PBDEs was observed with greater concentrations of OH-PBDEs at coastal areas than inland regions in China. [Copyright &y& Elsevier]

Abstract: Infrared transmission and emission spectroscopy were used to analyze the difference in structure and thermal behavior of two Chinese palygorskites. The position of the main bands identified in the infrared spectra of the palygorskites studied is similar for these two Chinese samples, but there are some differences in their intensity, which is significant. This discrepancy is attributed to the existence of impurities and the geological environments in different regions. The infrared emission spectra clearly show the structural changes and dehydroxylation of the palygorskites when the temperature is raised. The dehydration of the palygorskites is followed by the loss of intensity of the OH stretching vibration bands in the region of 3600–3200cm−1. Dehydroxylation is followed by the decrease in intensity in the bands between 3700 and 3550cm−1. Dehydration of pure palygorskite was completed by 600°C. Partial loss of coordinated water was observed at 400°C. Infrared emission spectroscopy is an effective method to determine the stability of the mineral. [Copyright &y& Elsevier]

Abstract: High concentrations of polybrominated diphenyl ethers (PBDEs) and their structural analogues (such as methoxylated (MeO) and hydroxylated (OH) PBDEs) had been observed in environmental samples and human tissues. This study evaluated the occurrence, potential source and human exposure of these organobrominated compounds via market fish consumption in Hong Kong. The contamination of 22 PBDEs, 7 MeO-BDEs, 15 OH-BDEs and 3 bromophenols (BRPs) were analyzed in 20 fish species (279 samples). The estimated daily intakes of PBDEs, MeO-BDEs, OH-BDEs and BRPs via fish consumption ranged from 4.4 to 14, 0.50 to 4.3, 0.02 to 0.43 and 0 to 0.21ng/kgday for Hong Kong residents, respectively, based on 50th and 95th centile concentrations. BDE-47 and 99 were found to be the major PBDE congeners while 2′-MeO-BDE-68, 6-MeO-BDE-47 and 3-MeO-BDE-47 were the dominant MeO-BDEs. Concentrations of OH-BDEs and BRPs were 10–100-fold less than those of PBDEs, with small frequencies of detection (max 36.7%). Dietary intake of PBDEs via fish consumption by Hong Kong residents was greater than many developed countries, such as the USA, UK, Japan and Spain. To our knowledge, this is the first report to estimate the dietary intake of MeO/OH-BDEs and BRPs via fish consumption. Our results indicated that the toxicity potential of these compounds should not be neglected. [Copyright &y& Elsevier]

Abstract: The anti-bacterial agent mequindox is widely used as an animal feed additive in China. Its potential effect on host cells, however, remains largely unknown. Here, we report that pig CYP3A22 represents an important metabolic enzyme in mequindox catalysis. Interestingly, we found that ectopic expression of CYP3A22 reversed the mequindox-induced G2 cell cycle accumulation in cultured pig hepatocytes. To further probe the catalytic mechanism of CYP3A22 in mequindox metabolism, we identified 2′-acetyl-hydroxylation as a major catalytic step of CYP3A22-dependent mequindox metabolism using LC–MS/MS spectrometry. Together, our study suggests that CYP3A22 plays an important role in mequindox metabolism via 2′-acetyl-hydroxylation. [Copyright &y& Elsevier]

Abstract: Thermogravimetric analysis–mass spectrometry, X-ray diffraction and scanning electron microscopy (SEM) were used to characterize eight kaolinite samples from China. The results show that the thermal decomposition occurs in three main steps (a) desorption of water below 100°C, (b) dehydration at about 225°C and (c) well defined dehydroxylation at around 450°C. It is also found that decarbonization took place at 710°C due to the decomposition of calcite impurity in kaolin. The temperature of dehydroxylation of kaolinite is found to be influenced by the degree of disorder of the kaolinite structure and the gases evolved in the decomposition process can be various because of the different amount and kinds of impurities. It is evident by the mass-spectra that the interlayer carbonate from impurity of calcite and organic carbon is released as CO2 around 225, 350 and 710°C in the kaolinite samples. [ABSTRACT FROM AUTHOR]

Abstract: Two kinds of coal-bearing kaolinite from China were analysed by X-ray diffraction (XRD), Thermogravimetric analysis–mass spectrometry (TG–MS), infrared emission spectroscopy. Thermal decomposition occurs in a series of steps attributed to (a) desorption of water at 68°C for Datong coal-bearing strata kaolinite and 56°C for Xiaoxian with mass losses of 0.36% and 0.51%, (b) decarbonization at 456°C for Datong coal-bearing strata kaolinite and 431°C for Xiaoxian kaolinite, (c) dehydroxylation takes place in two steps at 589 and 633°C for Datong coal-bearing strata kaolinite and at 507 and 579°C for Xiaoxian kaolinite. This mineral was further characterised by infrared emission spectroscopy (IES). Well-defined hydroxyl stretching bands at around 3695, 3679, 3652 and 3625cm−1 are observed. At 650°C all intensity in these bands is lost in harmony with the thermal analysis results. Characteristic functional groups from coal are observed at 1918, 1724 and 1459cm−1. The intensity of these bands decrease by thermal treatment and is lost by 700°C. [ABSTRACT FROM AUTHOR]

A combined study of mineral O isotopes and hydroxyl contents was carried out for the contacts between ultrahigh-pressure eclogite and gneiss from main hole of the Chinese Continental Scientific Drilling Project in the Sulu orogen. While there is a large δ18O variation from −8.3 to 7.3‰ for all minerals, different styles of mineral-pair fractionation occur at the boundaries of different lithologies. Both equilibrium and disequilibrium O isotope fractionations are observed between quartz and the other minerals, with reversed fractionations between omphacite and garnet in some samples of eclogite. This suggests that both eclogite and gneiss acquired their negative δ18O values by meteoric-hydrothermal alteration of their protoliths at high temperatures before subduction, and that fluid-assisted O isotope exchange did take place across the boundary of different lithologies at local scales during amphibolite-facies retrogression. Fourier Transform Infrared Spectroscopy analysis yielded H2O concentrations of 50 to 1144 p.p.m. (by weight) for garnet and 139 to 751 p.p.m. for omphacite. The state of equilibrium or disequilibrium O isotope fractionations between omphacite and garnet are correlated with variations in their water content at local scales, indicating that the internally derived fluid plays a critical role in retrograde metamorphism during exhumation. The retrograde metamorphism results in mineral reactions and O isotope disequilibria between some of the minerals, but the fluid for retrogression was derived from the decompression exsolution of structural hydroxyl and thus internally buffered in the O isotope composition. A quantitative estimate suggests that a hand specimen (3 × 6 × 9 cm) of eclogite composed of 70% garnet and 30% omphacite can release 0.316 g water by the decompression exsolution of structural hydroxyl, which can form 14.4 g amphibole during exhumation. This provides sufficient amounts of water for the amphibolite-facies retrogression. [ABSTRACT FROM AUTHOR]

Reports findings of hydroxyl-rich topaz in the Sulu kyanite quartzite from eastern China. Discussion of the petrochemical characteristics and stabilities of hydroxyl-rich topaz; Role of fluid in metamorphic processes related to continental subduction and collision; Origin of woodhouseite.