• Correlation analysis between the Aral Sea shrinkage and the Amu Darya River

    分类: 地球科学 >> 地理学 提交时间: 2023-07-17 合作期刊: 《干旱区科学》


  • Adsorption behavior of uranyl ions onto amino-type adsorbents prepared by radiation-induced graft copolymerization

    分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》

    摘要:Amino-type adsorbents (ATAs) were prepared by radiation-induced graft copolymerization of 4-hydroxybutyl acrylate glycidyl ether (HB) onto a polyethylene-coated polypropylene (PE/PP) duplex fiber of a non-woven fabric, and modified with different amines of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and diethylamine (DEA). The adsorption behavior of uranyl ions onto the ATAs was studied in batch experiments. The effects of the contact time, initial concentration of the ions, temperature, and pH value. The salinity were investigated along with the adsorption kinetics and the adsorption isotherms. The kinetic experimental data followed the pseudo second-order kinetic model, and the adsorption isotherms correlated well with the Langmuir model. The ATAs showed good efficiency in adsorbing uranyl ions, with the best saturation adsorption capacity being 64.26 mg g-1 for ATA-DETA within 120 min. The temperature dependence of ATA-DETA was quite abnormal and the quickest behavior was obtained at 25 ℃. ATAs showed good adsorption capacity over a wide pH range of 4.0–8.5, and HCl could be used in the elution process. Salinity of the solution had great effect on the adsorption capacity, 3.5% salinity resulted in a 55% loss of capacity from ATA-DETA. The selectivity of ATA-DETA showed an order of: UO22+ Fe3+ > Zn2+ > VO3- > Co2+ > Ni2+.

  • Bromate formation in bromide-containing waters irradiated by gamma rays

    分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》

    摘要:The formation of bromate, a classified potential carcinogen, is of great concern when disinfection processes are used for treating high-bromide drinking waters. Bromide-containing aqueous solutions with various additives were irradiated by 60Co γ source. With a 2.0 kGy irradiation of N2O-saturated solutions at initial bromide concentrations of 180.2 μgl-1, 416.9 μgl-1, 663.1 μgl-1 and 823.9 μgl-1. 79.5%, 84.0%, 87.3% and 88.3% of bromide ions were transformed to bromate, respectively. Addomg CO32-/HCO3- or NO3- ions into N2O-saturated bromide solutions, the amount of bromate ions formed decreased with increasing concentrations of the additives. On the other hand, the bromate concentration was all below the detection limit of 1 μgl-1 whenever N2O was not added to quench eaq- and ·H. The results indicated that γ-rays irradiation could be used as a disinfection process, instead of ozonation, to comply with upcoming more stringent regulations, especially in waters containing high concentrations of bromide.

  • A new specimen of Parabohaiornis martini (Avialae: Enantiornithes) sheds light on early avian skull evolution

    分类: 生物学 >> 动物学 提交时间: 2023-02-17 合作期刊: 《古脊椎动物学报》

    摘要:The Enantiornithes is the most speciose clade of Mesozoic avialans with over 60 named taxa reported from most continents that span the whole Cretaceous. Most of the fossil remains of this clade, as well as those of other early diverging avialans are preserved in twodimensions. This complicates to extract detailed anatomical information from the skull, in which the composite elements are delicate and thus not easily observable through conventional methods. The scarcity of well-preserved early avialan skulls, as well as the limited number of specimens that have been analyzed using computed tomography scanning, consequently circumscribes a large morphological gap in the fossil record during the transition from the heavy and akinetic dinosaurian skull to the lightweight and kinetic bird skull. Here, we present a threedimensional digital reconstruction of the skull and part of the cervical vertebrae of a new specimen of the enantiornithine Parabohaiornis martini from the Early Cretaceous of China. Our results demonstrate that Parabohaiornis retains the plesiomorphic non-avialan dinosaurian temporal and palatal reinforcing the recent hypothesis that the temporal and palatal regions are evolutionarily conservative and that the akinetic skull has been conserved well into of early branching avialans.

  • First report of immature feathers in juvenile enantiornithines from the Early Cretaceous Jehol avifauna

    分类: 生物学 >> 动物学 提交时间: 2019-08-27 合作期刊: 《古脊椎动物学报》

    摘要:Molting—the process replacing one plumage with another—is a critically important biological function in Aves. This process annually replaces the feather coat, damaged by normal wear and tear, produces ontogenetic changes in feathering, and produces alternate breeding plumages associated with reproductive activity in adults. Immature, growing feathers are encased in a keratinous sheath, giving them a narrow, tubular, and featureless appearance. The complete loss of the sheath indicates the feather is mature. Despite the wealth of integumentary data published from the Jehol Biota, immature feathers have never been definitively reported, although they may potentially be preserved in a juvenile specimen of the non-avian oviraptorosaur theropod dinosaur Similicaudipteryx from the 120 Ma Jiufotang Formation. A developing feather has been reported in a 99 Ma enantiornithine neonate preserved in Burmese amber, in which three-dimensional preservation makes interpretations of integumentary structures more straightforward. Here we report on probable immature feathers in four juvenile enantiornithines (Aves: Ornithothoraces) from the Jehol Group. As observed in developing feathers in extant birds, the purported immature fossil feathers appear proximally narrow and featureless with barbs protruding only distally. Based on our observations, we suggest that similar-appearing feather structures preserved on the manus and tibiotarsus in the holotype of the enantiornithine Cruralispennia multidonta may alternatively be interpreted as immature feathers. The presence of immature feathers in combination with sexually dimorphic ornamental feathers in juvenile enantiornithines suggests the complex molting patterns of Neornithes, in which such ornaments only appear after several years (following several molts) when reproductive activity is achieved, are limited to a subset of crownward avians.

  • Conditional knock-out of lipoic acid protein ligase 1 reveals redundancy pathway for lipoic acid metabolism in Plasmodium berghei malaria parasite

    分类: 生物学 >> 生态学 提交时间: 2017-11-17

    摘要:Background: Lipoic acid is a cofactor for a-keto acid dehydrogenase system that is involved in the central energy metabolism. In the apicomplexan parasite, Plasmodium, lipoic acid protein ligase 1 (LplA1) and LplA2 catalyse the ligation of acquired lipoic acid to the dehydrogenase complexes in the mitochondrion. The enzymes LipB and LipA mediate lipoic acid synthesis and ligation to the enzymes in the apicoplast. These enzymes in the lipoic acid metabolism machinery have been shown to play important roles in the biology of Plasmodium parasites, but the relationship between the enzymes is not fully elucidated. Methods: We used an anhydrotetracycline (ATc)-inducible transcription system to generate transgenic P. berghei parasites in which the lplA1 gene was conditionally knocked out (LplA1-cKO). Phenotypic changes and the lplA1 and lplA2 gene expression profiles of cloned LplA1-cKO parasites were analysed.Results: LplA1-cKO parasites showed severely impaired growth in vivo in the first 8 days of infection, and retarded blood-stage development in vitro, in the absence of ATc. However, these parasites resumed viability in the late stage of infection and mounted high levels of parasitemia leading to the death of the hosts. Although lplA1 mRNA expression was regulated tightly by ATc during the whole course of infection, lplA2 mRNA expression was significantly increased in the late stage of infection only in the LplA1-cKO parasites that were not exposed to ATc. Conclusions: The lplA2 gene can be activated as an alternative pathway to compensate for the loss of LplA1 activity and to maintain lipoic acid metabolism.

  • A fully human monoclonal antibody targeting PD-L1 with potent anti-tumor activity

    分类: 生物学 >> 生物物理学 >> 免疫学 提交时间: 2016-05-05

    摘要:Background: Programmed cell death ligand-1 (PD-L1) with its receptor PD-1 pathway is overactivated in many tumors. Inhibiting the interaction of PD-L1 and PD-1 is an attractive strategy to restore tumor-specific T cell immunity for tumor therapy. Methods: A fully human anti-PD-L1 monoclonal antibody (mAb) B60-55 was identified by yeast surface display. The affinity, specificity, activity, and efficacy of mAb B60-55 were investigated in vitro or in vivo. Results: mAb B60-55 (purity >99%) could bind to PD-L1 that is expressed on HEK293 cells with a dissociation constant of 02 nM, and specifically bind to human or cynomolgus macaque PD-L1 without a cross-reaction with murine PD-L1. Moreover, mAb B60-55 is an antagonistic antibody, which can block PD-L1 binding to its receptors, including PD-1 (PDCD1) and B7.1 (CD80). In vitro assays demonstrated the ability of mAb B60-55 to enhance T cell responses and cytokine production in the mixed lymphocyte reaction. In vivo studies showed that administration of mAb B60-55 exhibited a potent antitumor activity toward tumor cell carcinoma xenograft, with a mean half-life of 177.9 h in cynomolgus monkeys. Conclusion: mAb B60-55 is a potential candidate for clinical development in cancer treatment. (C) 2016 Elsevier B.V. All rights reserved.