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Due to the high viscosity and bulk complexity of crude oil samples, it poses a grand challenge to determine hydrogen sulfide (H2S) in them. Although many methods have been developed for the analysis of H2S in complex systems, these methods generally have complex processes, large analysis error and low sensitivity. In the study, based on the reaction between triazine and H2S by generating thiadiazine, a small volume of complex crude oil sample was introduced directly into a triazine solution using acetonitrile as solvent for transferring H2S into detectable species by organic mass spectrometry. The experimental parameters of solution composition, acetic acid content, reaction time and reaction temperature were optimized, and the method of paper spray ionization-mass spectrometry (PSI-MS) was established for rapid analysis of H2S in complex crude oil samples. An optimal performance was achieved when the reaction of triazine and H2S was carried out at 30 ℃ for 2 h with acetonitrile containing 0.1% acetic acid as solvent. The standard curve for the quantitative analysis of H2S was constructed according to the linear relationship between MS signal intensity of resulting thiadiazine and the concentration of H2S, which was applied for actual crude oil samples from different sources. The results showed that the linear range and the limit of detection (LOD) were 0.1-1 000 μg/L and 0.041 μg/L with intra-day precision of 3.04% and inter-day precision of 3.18%, respectively. The PSI-MS was also employed to determine H2S in different actual crude oil samples, and the spiked recovery was 91.7%-103.5% with relative standard deviation (RSD) of 1.2%-4.5%. This method has the advantages of easy operation, low cost, high sensitivity and less contamination to mass spectrometer, which is promising for the direct and fast analysis of H2S in complex crude oil samples.

The West Liao River (WLR) and Yellow River (YR) basins are two major centers of millet farming in northern China. The result from flotation analyses and the spatial distribution of archeological sites indicate that two distinct survival strategies—agriculture and pastoralism were adopted in the southern and western regions of the WLR. Previous studies of ancient populations from the western area of the WLR suggested a correlation between a pastoral economy in the Bronze Age Upper Xiajiadian culture with a decreased genetic affinity with YR farmers. However, the population history of the southern WLR is unknown mainly due to the lack of ancient genetic data. Here we report the genomic data of an ancient individual from the Majiazishan site from the Late Bronze Age southern WLR region associated with Upper Xiajiadian culture. Unlike individuals from western WLR, this individual derived ancestry entirely from Late Neolithic YR farmers. We found a genetic substructure of the ancient human population of Upper Xiajiadian culture, which is consistent with the differences in the subsistence strategies of western and southern WLR. Climate deterioration led to different populations occupying the west and the south, respectively, in the WLR: the nomadic population from the Amur River (AR) in the west and the agricultural population from the YR in the south. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) are an important class of environmental pollutants, and there is much interest in China to eliminate such pollutants. Noble metal catalysts have long been a family of catalysts with high efficiency and good low-temperature catalytic activity. As a representative of the noble metals, Pt has been widely used. This paper reviews the research trend of Pt-based catalysts for the catalytic oxidation of VOCs, and it compares several important components of Pt-based catalysts. The size of Pt particles, supported carriers, and reaction mechanism are reviewed. Toluene in VOCs is the main research subject. The activity, stability, water resistance, and selectivity of a series of Pt-based catalysts are summarized. [ABSTRACT FROM AUTHOR]

Geum longifolium (Maxim.) Smedmark 2006 belongs to the family Rosaceae, subfamily Rosoideae, tribe Colurieae. Geum longifolium is endemic to China and its whole herb is used in Chinese medicine. Here, the first complete chloroplast (cp) genome of G. longifolium was assembled and annotated based on genome skimming, and its phylogenetic position was investigated using phylogenomic evidence. The cp genome size of G. longifolium was 155,884 bp with the total GC content of 36.7%. Its cp genome presented a typical tetrad structure, composed of a large single copy (LSC) region (85,338 bp), a small single copy (SSC) region (18,358 bp), and a pair of inverted repeat (IR) regions (26,094 bp). The cp genome encoded 129 genes, including 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analysis indicated that G. longifolium was sister to G. elatum Wall. ex G.Don 1832 in current taxa sampling. This study can enrich the chloroplast genomic resource of Geum and lay the foundation for future phylogenetic studies on Geum. [ABSTRACT FROM AUTHOR]

In recent studies of crustal growth using global zircon Hf–O isotopic datasets, high-δ18O zircons are typically attributed to intra-crustal reworking during which very little juvenile mantle-derived magmas were added to the crust. Although arc magmas may originate from a high-δ18O mantle wedge, it has been difficult to decipher the contribution of high-δ18O mantle to zircon-saturated felsic magma due to superimposed intra-crustal processes. We address this issue by combining the data from high-δ18O zircon-bearing ultramafic cumulates and coeval lavas from a Cretaceous magmatic arc in southern Tibet. The cumulates mainly consist of different proportions of cumulus olivine and intercumulus amphibole. Amphibole analyses show a transition from increasing to decreasing Zr with increasing SiO2 (50–74 wt.%) contents in the intercumulus melts, indicating zircon saturation in late-stage interstitial melts. The εNd(t) values (2.4 ± 1.4) of the apatite grains crystallized before and after zircon remain almost constant. Interstitial zircons have δ18O (6.1–7.2‰) values similar to the earliest crystallized olivine (δ18O = 6.3–7.1‰) in the cumulates. The coeval lavas may represent the intercumulus melts extracted from amphibole-rich cumulates at different depths. Both the lavas and cumulates were ultimately derived from high-δ18O arc mantle modified by small amounts (<12%) of subducted sediments, and crystallized zircon during intra-crustal magma evolution without involving crustal contamination or melting. These high-δ18O zircons therefore are not products of crustal reworking, but record crustal growth during their crystallization (110 ± 2 Ma). Our study shows that the combination of zircon and olivine oxygen isotopes for ultramafic to felsic rocks is more effective than zircon data alone in evaluating the role of crustal growth vs. reworking in an arc system. The implication is that global zircon-based crustal evolution models that attribute all high-δ18O zircons to crustal reworking may conceal recent crustal growth. [ABSTRACT FROM AUTHOR]