Browsing by Author "Jin, X."
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Item A contribution to common Carius tube distillation techniques(Journal of Analytical Atomic Spectrometry, 2013-02) Jin, X.; Li, W.; Xiang, P.; Sakyi, P.A.; Zhu, M.; Zhang, L.In this paper, we introduce an economic electrothermal timing steamer for common Carius tube Os in situ distillation. It is suitable for analysing several batches of samples. Its configuration allows the Carius tubes to be properly fixed and bathed in steam into which the tubes are immersed. The top of each Carius tube is sealed with a stretchy rubber head through which a pair of teflon tubes pierce, serving as inlet and outlet for clean air and OsO4 respectively. At steam temperatures of 99-100 °C, OsO4 in the sample solutions inside the Carius tubes is evaporated out and subsequently carried by clean air to the trapping water in an ampoule bottle, immersed in a box filled with ice. In the present study the steamer allowed for the convenient, efficient and simultaneous distillation of Os from seven samples with near ninety percent recovery. The blank values were 0.42 ± 0.15 pg and 0.26 ± 0.05 for 187Os and 187Os/ 188Os (n = 4). The dating results of reference materials (RMs) namely Henderson, HLP and JDC were in accordance with reference and certified values within the range of uncertainties. The special steamer has successfully been used in the analysis of pyrite samples for the distillation of Os. © 2013 The Royal Society of Chemistry.Item Early Mesozoic tectono-magmatic activity and mineralization in northeast China: Evidence from Re-Os to U-Pb studies of the Taipingchuan porphyry Cu-Mo deposit in the Derbugan metallogenic belt(International Geology Review, 2014-10) Zhang, L.; Gao, B.; Li, W.; Chen, Z.; Sakyi, P.A.; Jin, X.The Taipingchuan Cu-Mo deposit is a recently discovered large porphyry deposit located in the north of the Derbugan metallogenic belt of northeastern China. The geochronological data of the deposit yielded a Late Triassic zircon U-Pb age of 202 ± 6 Ma from a granodiorite porphyry that hosts the Cu-Mo mineralization. Measured Re-Os isotopes of seven disseminated molybdenite samples yielded an isochron age of 200 ± 5 Ma with mean square of weighted deviates of 2.7, while those of seven veinlet molybdenite samples also produced an isochron age of 200.1 ± 2.5 Ma and mean square of weighted deviates of 3.3. These isochron ages show that a Cu-Mo mineralization event occurred at ca. 200 Ma. Based on regional tectonic evolution, we propose that the Late Triassic Cu-Mo mineralization of the host porphyry in the Derbugan metallogenic belt was mainly associated with the subduction of the Mongol-Okhotsk Ocean slab under the Ergun block, contrary to previous suggestion that it was related to the subduction of the Mesozoic Palaeo-Pacific plate. © 2014 Taylor & Francis.Item LLHR-type chalcopyrite Re-Os geochronology and geochemistry of the Xiaotongchang Cu deposit in south Ailaoshan and its geological significances(Journal of Geochemical Exploration, 2019-03) Li, W.; Gao, B.; Zhang, L.; Jin, X.; Sakyi, P.A.The Xiaotongchang Cu deposit is located in the south Ailaoshan and at the contact between Yunnan province of China and Vietnam. Four Cu ore bodies are distributed parallel to each other in an interlayer fracture zone in the Permian Emeishan basalt. The major ore mineral in the deposit is chalcopyrite, and the main gangue minerals are quartz and calcite. New Re-Os data for chalcopyrite from the Xiaotongchang Cu deposit show tens of ppb Re abundances (1–86 ppb) and contain essentially no common Os. All the samples have extremely high 187Re/188Os (up to 2.3 × 104), and the dominance of radiogenic Os and high 187Re/188Os are diagnostic features of “LLHR” (low-level, highly radiogenic) sulfides. The Re-Os isochrone age for the No. 1 and No. 3 Cu bodies show that the phase of Cu mineralization predominantly occurred in the Middle Triassic, with an age of 230.6 ± 1.1 Ma. Thus, the mineralization occurred much later than the periods of major eruption of the Emeishan large igneous provinces, indicating a closer relationship with the late collisional processes in the Ailaoshan orogenic belt. Combined with REEs patterns and consistently positive δ34S values (7.4–9.2‰), it can be concluded that the ore-forming materials of the Cu deposit are derived from a mixture of mantle and crust components.Item A new modification of the sample introduction system for Os isotope ratio measurements(Journal of Analytical Atomic Spectrometry, 2011-06) Jin, X.; Du, A.; Li, W.; Xiang, P.; Sakyi, P.A.; Zhang, L.Here we present a new modification of the sample introduction system aimed at precisely measuring Os isotope ratios. A small glass connector was used to transfer OsO4 vapor from a Carius tube into a nebulizer. After dissolution of sample in a Carius tube, Os isotopes in the sample were determined simultaneously through in situ distillation without any prior separation procedure. The analytical precision at intermediate precision conditions of measurement was improved through the simultaneous introduction of Os via sparging and the aspiration of a solution containing Ir for mass bias correction. The present method, which involves the passage of Os vapor directly into the ICP-MS torch, thus solves the problems encountered previously when optimizing an instrument. The dating results of reference materials (RMs) HLP and JDC by the modified method are 221.8 ± 0.70 Ma (0.31%, 2s, n = 7) and 140.0 ± 0.44 Ma (0.31%, 2s, n = 9) respectively, which are consistent with their certified values of 221.4 ± 5.6 Ma and 139.6 ± 3.8 Ma respectively. Also reported in this study are dating results of several unknown molybdenite samples by the new method. © 2011 The Royal Society of Chemistry.Item A novel HIV T helper epitope-based vaccine elicits cytokine-secreting HIV-specific CD4+ T cells in a Phase I clinical trial in HIV-uninfected adults(Vaccine Journal, 2009) Newman, M.J.; Jin, X.; De-Rosa, S.; Cooper, C.; Thomas, E.; Keefer, M.; Fuchs, J.; Blattner, W.; Livingston, B.D.; McKinney, D.M.; Noonan, E.; Decamp, A.; Defawe, O.D.; Wecker, M.A Phase I human vaccine trial of a novel polypeptide vaccine of HIV T helper epitopes (EP-1043) and a DNA vaccine of HIV CTL epitopes was conducted in 84 healthy adult volunteers. The vaccine immunogenicity was assessed by an intracellular cytokine staining assay for IL-2, IL-4, TNF-alpha and IFN-gamma. Sixty eight percent (32/47) of subjects had a positive CD4+ T response after receiving two vaccinations of the polypeptide vaccine. The responding CD4+ T cells made various combinations of IL-2, IL-4, IFN-gamma, and TNF-alpha. The study demonstrated that the EP-1043 vaccine is safe, well-tolerated, and immunogenic.