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Fan H.,Beijing University of Technology | Peng Y.,Beijing University of Technology | Li Z.,Changchun Gold Research Institute | Chen P.,North China Pharmaceutical Group Corporation | And 2 more authors.
Journal of Polymer Research | Year: 2013

Hydrophobic symmetric flat-sheet membranes of polyvinylidene fluoride (PVDF) for use in vacuum membrane distillation (VMD) were successfully fabricated by the vapor-induced phase separation (VIPS) method using the double-layer casting process. To avoid the delamination that often occurs in double-layered membranes, the same PVDF polymer was employed in both the upper layer and support layer casting solutions. Solutions with low and high PVDF contents were co-cast as the upper layer and support layer of the membrane that was formed. In the VIPS process, the low PVDF content solution favored the formation of a layer with a porous and hydrophobic surface, whereas the solution with a high PVDF concentration favored the formation of a layer with high mechanical strength. The effect of the vapor-induced time on the morphological properties of the membranes was studied. As the vapor-induced time was increased, the cross-section of the membrane changed from an asymmetrical finger-like structure to a symmetrical sponge-like structure, and the surface of the membrane became rough and porous. The membrane subjected to the longer vapor-induced time also exhibited a higher permeating flux during the VMD process. The best PVDF membrane fabricated in this study had a mean radial pore size of 0.49 μm, and the rough upper surface produced a static contact angle of 145 with water. During the VMD process with a 3.5 wt.% sodium chloride (NaCl) aqueous solution, the best membrane that was fabricated produced a permeating flux of 22.4 kg m-2 h-1 and an NaCl rejection rate of 99.9 % at a feed temperature of 73 C and a downstream pressure of 31.5 kPa. This performance is comparable to or superior to the performances of most of the flat-sheet PVDF membranes reported in the literature and a polytetrafluoroethylene membrane used in this study. © 2013 Springer Science+Business Media Dordrecht.

Ye Q.,State Key Laboratory Breed Base Of Complex Nonfer Metal Rsrc Cleaning Utilization In Yunnan Province | Ye Q.,Kunming University of Science and Technology | Zhu H.,State Key Laboratory Breed Base Of Complex Nonfer Metal Rsrc Cleaning Utilization In Yunnan Province | Zhu H.,Kunming University of Science and Technology | And 8 more authors.
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2013

Preparation of the reduced iron powder has been attempted with mill scale as the iron-bearing material and with wood charcoal as the reducing agent through microwave heating. The response surface methodology (RSM) is used to optimize the process conditions, with wood charcoal, process temperature, and holding time being the three process parameters. The regressed model equation eliminating the insignificant parameters through an analysis of variance (ANOVA) was used to optimize the process conditions. The optimum process parameters for the preparation of reduced iron powders have been identified to be the wood charcoal of 13.8 pct, a process temperature of 1391 K (1118°C), and a holding time of 43 minutes. The optimum conditions resulted in reduced iron powders with a total iron content of 98.60 pct and a metallization ratio of 98.71 pct. X-ray fluorescence (XRF) was used to estimate the elemental contents of the reduced iron powder, which meets the specification of the HY100.23 first-class iron powder standard. Additionally X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) analysis were performed and the results are compiled. © 2013 The Minerals, Metals & Materials Society and ASM International.

Li B.-L.,Jilin University | Shen X.,Jilin University | Chen G.-J.,Jilin University | Yang Y.-Q.,Jilin University | Li Y.-S.,Changchun Gold Research Institute
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2012

The Asiha gold ore deposit is located in the east part of the middle uplifted basement and granitic belt which is one important gold and ferro-polymetallic metallogenic belt in eastern Kunlun. The Early Indosinian diorite and biotite granite are the main ore-hosting rocks, while the NNE and NW-trending faults are major ore-bearing structures in the mine area. Vein I is one of the major auriferous veins, and is closely related to the minette spatially. Fluid inclusions in quartz crystals can be classified into aqueous two-phase and CO2-rich three-phase inclusion. Salinities of fluid inclusions contents of NaCl range from 1.83% to 8.13%, densities range from 0.69 to 0.87 g/cm3, and homogenization temperatures range from 155.3°C to 425.6°C. In mineralization stage I, fluid inclusions are characterized by low salinity, high-temperature, and CO2-rich. In mineralization stage II, CO2-rich fluid inclusions and gas-liquid two-phase inclusions coexist, which show the immiscibility or boiling characterized by CO2 escaping, and resulted in salinity increasing of the residual fluid. Fluid inclusions in mineralized stage III are the gas-liquid two-phase inclusions. Charteristics of fluid inclusions, accompanied with H, O, S isotopic compositions, indicates that the ore-forming fluid is mainly mantle-derived and additional meteoric water in the late stage. By analyzing of Laser Raman spectrum, the gas-phase in fluid inclusions chiefly make up of CO2, CH4 and N2. According to the diagram of isochore, the ore-forming pressure can be calculated to almost 98-132 MPa, the ore-forming depth ranges from 8.16-9.58 km. By contrast to other typical orogenic gold deposits, A conclusion can be safely darwn that Asiha gold deposit belongs to the mesozonal orogenic gold deposit, and the gold mineralization occured in the transition period from compression to extension tectonic environment during intro-continental orogenic movement in Early Indosinian.

Cao Y.,Jilin University | Qin Y.,Jilin University | Qin Y.,Changchun Gold Research Institute | Bruist M.,University of the Sciences in Philadelphia | And 4 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2015

Formation and dissociation of the interstrand i-motifs by DNA with the sequence d(XnC4Ym) (X and Y represent thymine, adenine, or guanine, and n, m range from 0 to 2) are studied with electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), and UV spectrophotometry. The ion complexes detected in the gas phase and the melting temperatures (Tm) obtained in solution show that a non-C base residue located at 5′ end favors formation of the four-stranded structures, with T > A > G for imparting stability. Comparatively, no rule is found when a non-C base is located at the 3′ end. Detection of penta- and hexa-stranded ions indicates the formation of i-motifs with more than four strands. In addition, the i-motifs seen in our mass spectra are accompanied by single-, double-, and triple-stranded ions, and the trimeric ions were always less abundant during annealing and heat-induced dissociation process of the DNA strands in solution (pH∈=∈4.5). This provides a direct evidence of a strand-by-strand formation and dissociation pathway of the interstrand i-motif and formation of the triple strands is the rate-limiting step. In contrast, the trimeric ions are abundant when the tetramolecular ions are subjected to collision-induced dissociation (CID) in the gas phase, suggesting different dissociation behaviors of the interstrand i-motif in the gas phase and in solution. Furthermore, hysteretic UV absorption melting and cooling curves reveal an irreversible dissociation and association kinetic process of the interstrand i-motif in solution. [Figure not available: see fulltext.] © 2015 American Society for Mass Spectrometry.

Peng Y.,Beijing University of Technology | Dong Y.,Beijing University of Technology | Fan H.,Beijing University of Technology | Chen P.,North China Pharmaceutical Group Corporation | And 2 more authors.
Desalination | Year: 2013

Polysulfone (PSf) flat-sheet membranes with bi-continuous porous surfaces for direct-contact membrane distillation (DCMD) were successfully fabricated using a vapor-induced phase separation (VIPS) method. The present investigation revealed how the surface and cross-sectional morphology of PSf membranes and the desalination performance in DCMD were affected by exposure time, PSf content and relative humidity of air. In the VIPS process, an increase in exposure time led to a replacement of the bi-continuous top surface with a dense skin and to a large decrease in the permeate flux in DCMD. The best PSf membrane fabricated in this study had a mean pore radius of 0.32μm, water contact angle of 106.4°, the liquid entry pressure of water of 300kPa, and total porosity of 82.1%. During the DCMD process with a 35g/L sodium chloride solution, the best membrane produced a permeate flux of 30.0kgm-2h-1 and a very low conductivity of distilled water at hot-feed and cold-distillate side temperatures of 73°C and 25°C, respectively. The thickness of the hydrophobic layer of the membranes was first measured using the weight method, and its value was used in a simulation of the DCMD process. © 2013 Elsevier B.V.

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