Three-stage niobium mineralization at Bayan Obo, China.

The Chinese Bayan Obo deposit is a world-class rare earth element (REE) deposit with considerable niobium (Nb) and iron (Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead (U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites-key Nb-bearing minerals-are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312 ± 47 Ma (n = 99), 438 ± 7 Ma (n = 93), and 268 ± 5 Ma (n = 19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

Comparative study of reactive oxygen species and tetracycline degradation pathways in catalytic peroxodisulfate activation by asymmetric mesoporous TiO2 and the corresponding controlled-release materials.

The removal of trace amounts of antibiotics from water environments while simultaneously avoiding potential environmental hazards during the treatment is still a challenge. In this work, green, harmless, and novel asymmetric mesoporous TiO2 (A-mTiO2) was combined with peroxodisulfate (PDS) as active components in a controlled-release material (CRM) system for the degradation of tetracycline (TC) in the dark. The formation of reactive oxygen species (ROS) and the degradation pathways of TC during catalytic PDS activation by A-mTiO2 powder catalysts and the CRMs were thoroughly studied. Due to its asymmetric mesoporous structure, there were abundant Ti3+/Ti4+ couples and oxygen vacancies in A-mTiO2, resulting in excellent activity in the activation of PDS for TC degradation, with a mineralization rate of 78.6%. In CRMs, ROS could first form during PDS activation by A-mTiO2 and subsequently dissolve from the CRMs to degrade TC in groundwater. Due to the excellent performance and good stability of A-mTiO2, the resulting constructed CRMs could effectively degrade TC in simulated groundwater over a long period (more than 20 days). From electron paramagnetic resonance analysis and TC degradation experiments, it was interesting to find that the ROS formed during PDS activation by A-mTiO2 powder catalysts and CRMs were different, but the degradation pathways for TC were indeed similar in the two systems. In PDS activation by A-mTiO2, besides the free hydroxyl radical (·OH), singlet oxygen (1O2) worked as a major ROS participating in TC degradation. For CRMs, the immobilization of A-mTiO2 inside CRMs made it difficult to capture superoxide radicals (·O2-), and continuously generate 1O2. In addition, the formation of sulfate radicals (·SO4-), and ·OH during the release process of CRMs was consistent with PDS activation by the A-mTiO2 powder catalyst. The eco-friendly CRMs had a promising potential for practical application in the remediation of organic pollutants from groundwater.

Comparative study of the performance of controlled release materials containing mesoporous MnOx in catalytic persulfate activation for the remediation of tetracycline contaminated groundwater.

Controlled release materials (CRMs) are an emerging oxidant delivery technique for in-situ chemical oxidation (ISCO) that solve the problems of contaminant rebound, backflow and wake during groundwater remediation. CRMs were fabricated using ordered mesoporous manganese oxide (O-MnOx) and sodium persulfate (Na2S2O8) as active components, for the removal of antibiotic pollutants from groundwater. In both static and dynamic groundwater environments, persulfate can first be activated by O-MnOx within CRMs to form sulfate radicals and hydroxyl radicals, with these radicals subsequently dissolving out from the CRMs and degrading tetracycline (TC). Due to their excellent persulfate activation performance and good stability, the constructed CRMs could effectively degrade TC in both static and dynamic simulated groundwater systems over a long period (>21 days). The TC removal rate reached >80 %. Changing the added content of O-MnOx and persulfate could effectively regulate the performance of the CRMs during TC degradation in groundwater. The process and products of TC degradation in the dynamic groundwater system were the same as in the static groundwater system. Due to the strong oxidizing properties of sulfate radicals and hydroxyl radicals, TC molecules were completely mineralized within the groundwater systems, resulting in only trace levels of degradation products being detectable, with low- or non-toxicity. Therefore, the CRMs constructed in this study exhibited good potential for practical application in the remediation of organic pollutants from both static and dynamic groundwater environments.

Risk of Recurrence and Metastasis for Patients with T1N0M0 Esophageal Carcinoma Who Achieve Completed Resection via Endoscopic Submucosal Resection: Evidence for the Appropriateness of the Watch and Wait Follow-Up Strategy.

PURPOSE: Endoscopic submucosal dissection (ESD) is a widely performed procedure for esophageal carcinoma when the depth of invasion reaches the epithelium and lamina propria. However, ESD for esophageal carcinoma with depth of invasion exceeding the muscularis mucosa is controversial. This study aimed to evaluate the long-term outcomes of ESD for T1N0M0 (tumor invading the mucosa and submucosa [T1], no regional lymph node metastasis [N0], no distant metastasis [M0]) esophageal cancer. PATIENTS AND METHODS: Esophageal cancer was evaluated via pathology and computed tomography (CT) in consecutive patients with negative margin and without additional therapy. A total of 84 patients were included. The mean follow-up time was 42 (range, 9-99) months. RESULTS: No recurrence and metastasis were detected in the M1 and M2 group. The 5-year locoregional recurrence rate and distant metastasis rate were 4.2% and 5.6% for the M3 group and were 0% and 1.4% for the SM group, respectively. The 3- and 5-year overall survival were 94.4% (M1+M2 group, 95.0%; M3 group, 95.0%; SM group, 92.9%) and 80.9% (M1+M2 group, 95.0%; M3 group, 95.0%; SM group, 92.9%). Meanwhile, the 3- and 5-year disease-specific survival rates were 100% (M1+M2 group, 100%; M3 group, 100%; SM group, 100%) and 90.8% (M1+M2 group, 100%; M3 group, 90.0%; SM group, 85.7%). The major complications were postoperative strictures, most of which were grade 1-2. In total, two (4.8%) and one (1.2%) patient developed grade 3 and 5 late esophageal strictures, respectively. CONCLUSION: ESD complete resection yields low recurrence and metastasis rates in early esophageal cancer (T1N0M0). Thus, additional treatment is not necessary, and a watch and wait strategy may be reasonable.

Alcohol solvothermal reduction for commercial P25 to harvest weak visible light and fabrication of the resulting floating photocatalytic spheres.

In this study, to fabricate stable floating photocatalytic spheres, facile alcohol solvothermal reduction was first employed to modify commercial TiO2 (P25) photocatalysts to harvest visible light and improve their performances for photodegrading phenol in seawater exciting by visible light. Floating photocatalytic spheres were then prepared by loading reduced P25 photocatalysts on inner and outer surfaces of acrylic hollow spheres. The structural characterizations showed that reduction of P25 introduced disorder-crystalline shell-core structures with present Ti3+ in reduced P25 photocatalysts. These features facilitated visible light response and phenol degradation in seawater under visible light irradiation. As reduction time or temperature of alcohol solvothermal process rose, more Ti3+ and shell-core structures were introduced into reduced P25, resulting in higher performances towards phenol degradation in seawater. However, extended periods of time and elevated temperatures decreased disordered layer of reduced P25, deteriorating the photocatalytic performances. Thanks to good light transmission of the hollow spheres and the high performance of the reduced P25, the photocatalytic performances of spheres loaded with reduced P25 could effectively degrade phenol in seawater even at low concentrations. The removal rate of phenol by floating spheres reached more than 95% after 8 h. In addition, the floating spheres displayed good stability and convenient reusability after six repeated photocatalytic degradation for phenol in seawater, promising features for future treatment of organic pollutants in oceans.

Fabrication of Polyimide Membrane Incorporated with Functional Graphene Oxide for CO2 Separation: The Effects of GO Surface Modification on Membrane Performance.

Two kinds of isocyanate were used to modify graphene oxide (GO) samples. Then, polyimide (PI) hybrid membranes containing GO and modified GO were prepared by in situ polymerization. The permeation of CO2 and N2 was studied using these novel membranes. The morphology experiments showed that the isocyanate groups were successfully grafted on the surface of GO by replacement of the oxygen-containing functional groups. After modification, the surface polarity of the GO increased, and more defect structures were introduced into the GO surface. This resulted in a good distribution of more modified GO samples in the PI polymer matrix. Thus, the PI hybrid membranes incorporated by modified GO samples showed a high gas permeability and ideal selectivity of membranes. In addition, enhancement of the selectivity due to the solubility of CO2 played a major role in the increase in the separation performance of the hybrid membranes for CO2, although the diffusion coefficients for CO2 also increased. Both the higher condensability and the strong affinity between CO2 molecules and GO in the polymer matrix caused an enhancement of the solubility selectivity higher than the diffusion selectivity after GO surface modification.

Enhanced performance of polyimide hybrid membranes for benzene separation by incorporating three-dimensional silver-graphene oxide.

Graphene oxide-Ag nanoparticle composites were prepared through impregnation reduction using different reactants. Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analyses were performed to characterize differences in the morphologies of three different Ag-GO composites. Scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry analyses were also applied to evaluate the morphology and thermal stability of the hybrid membranes. Swelling-sorption and pervaporation experiments of benzene and cyclohexane were conducted to evaluate the separation performance of hybrid membranes containing different Ag-GO composites. Results demonstrated that small Ag nanoparticles generated through impregnation reduction using Ag(NH3)2(+) and PEG were homogeneously distributed in the hybrid membranes because of moderate reduction rate. The polymide (PI) hybrid membrane exhibited high separation performance. Increase in Ag content in the Ag-GO samples led to the formation of Ag particles on the GO surface; these particles enhanced the separation performance of the hybrid membranes. When Ag-GO samples with 15 mass percent added, the hybrid membrane showed the highest separation performance and its maximum separation factor in the pervaporation experiments reached 35. It is more than three times higher than that of the GO/PI hybrid membrane. Moreover, large Ag particles were formed and aggregated during the preparation and polymerization of Ag-GO samples with high Ag contents; these particles reduced the separation performance of the hybrid membranes.

[Preparation of weak light driven TiO2 multi composite photocatalysts via adsorption phase synthesis].

Photodegradation of pollutions by TiO2 under irradiation of weak UV and visible lights was one of the key points to expand the application of heterogeneous photocatalysis. Based on the adsorption phase synthesis, N doping and co-doping with N and Fe2O3 were employed to prepare TiO2 multi composite photocatalysts. The activity of these photocatalyts was evaluated by photodegradation of methyl-orange illuminated under weak UV and visible lights. Via UV-Vis diffuse reflectance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence spectra, the effects on the light absorption and visible response expansion of catalysts caused by different conditions were explored, such as sintering temperature, doping content of N and co-doping. Followed that, the changes in the photocatalytic activities were studied under the irradiation of weak light. The results showed that, N doping could enhance the light absorption of the catalysts, thus significantly enhanced their photocatalytic activity illuminated under UV weak light. All N-doped photocatalysts had a higher activity than the commercial available P25 photocatalyst. The visible response of catalysts was expanded little caused by N doping, thereby most catalysts doped by single N element had no activity illuminated by weak visible light. Only the catalyst doped with 5% of N element showed a weak activity after calcined at 900 degrees C . Due to the synergy effects between N doping and Fe2O3 coupling, co-doping did not only enhance the light absorption of the catalysts, but also significantly expanded the visible response of catalysts. So, co-doped catalysts showed a good catalytic activity when excited by weak visible light.

Enhanced Performance of Polyurethane Hybrid Membranes for CO2 Separation by Incorporating Graphene Oxide: The Relationship between Membrane Performance and Morphology of Graphene Oxide.

Polyurethane hybrid membranes containing graphene oxide (GO) with different morphologies were prepared by in situ polymerization. The separation of CO2/N2 gas mixtures was studied using these novel membranes. The results from the morphology characterization of GO samples indicated that the oxidation process in the improved Hummers method introduced oxygenated functional groups into graphite, making graphite powder exfoliate into GO nanosheets. The surface defects on the GO sheets increased when oxidation increased due to the introduction of more oxygenated functional groups. Both the increase in oxygenated functional groups on the GO surface and the decrease in the number of GO layers leads to a better distribution of GO in the polymer matrix, increasing thermal stability and gas separation performance of membranes. The addition of excess oxidant destroyed the structure of GO sheets and forms structural defects, which depressed the separation performance of membranes. The hybrid membranes containing well-distributed GO showed higher permeability and permeability selectivity for the CO2. The formation of GO aggregates in the hybrid membranes depressed the membrane performance at a high content of GO.

High mobility group-box 3 overexpression is associated with poor prognosis of resected gastric adenocarcinoma.

AIM: To elucidate high mobility group-box 3 (HMGB3) protein expression in gastric adenocarcinoma, its potential prognostic relevance, and possible mechanism of action. METHODS: Ninety-two patients with gastric adenocarcinomas surgically removed entered the study. HMGB3 expression was determined by immunohistochemistry through a tissue microarray procedure. The clinicopathologic characteristics of all patients were recorded, and regular follow-up was made for all patients. The inter-relationship of HMGB3 expression with histological and clinical factors was analyzed using nonparametric tests. Survival analysis was carried out by Kaplan-Meier (log-rank) and multivariate Cox (Forward LR) analyses between the group with overexpression of HMGB3 and the group with low or no HMGB3 expression to determine the prognosis value of HMGB3 expression on overall survival. Further, HMGB3 expression was knocked down by small hairpin RNAs (shRNAs) in the human gastric cancer cell line BGC823 to observe its influence on cell biological characteristics. The MTT method was utilized to detect gastric cancer cell proliferation changes, and cell cycle distribution was analyzed by flow cytometry. RESULTS: Among 92 patients with gastric adenocarcinomas surgically removed in this study, high HMGB3 protein expression was detected in the gastric adenocarcinoma tissues vs peritumoral tissues (P < 0.001). Further correlation analysis with patients' clinical and histology variables revealed that HMGB3 overexpression was obviously associated with extensive wall penetration (P = 0.005), a positive nodal status (P = 0.004), and advanced tumor-node-metastasis (TNM) stage (P = 0.001). But there was no correlation between HMGB3 overexpression and the age and gender of the patient, tumor localization or histologic grade. Statistical Kaplan-Meier survival analysis disclosed significant differences in overall survival between the HMGB3 overexpression group and the HMGB3 no or low expression group (P = 0.006). The expected overall survival time was 31.00 ± 3.773 mo (95%CI = 23.605-38.395) for patients with HMGB3 overexpression and 49.074 ± 3.648 mo (95%CI = 41.925-57.311) for patients with HMGB3 no and low-level expression. Additionally, older age (P = 0.040), extensive wall penetration (P = 0.008), positive lymph node metastasis (P = 0.005), and advanced TNM tumor stage (P = 0.007) showed negative correlation with overall survival. Multivariate Cox regression analysis indicated that HMGB3 overexpression was an independent variable with respect to age, gender, histologic grade, extent of wall penetration, lymph nodal metastasis, and TNM stage for patients with resectable gastric adenocarcinomas with poor prognosis (hazard ratio = 2.791, 95%CI = 1.233-6.319, P = 0.019). In the gene function study, after HMGB3 was knocked down in the gastric cell line BGC823 by shRNA, the cell proliferation rate was reduced at 24 h, 48 h and 72 h. Compared to BGC823 shRNA-negative control (NC) cells, the cell proliferation rate in cells that had HMGB3 shRNA transfected was significantly decreased (P < 0.01). Finally, cell cycle analysis by FACS showed that BGC823 cells that had HMGB3 knocked down were blocked in G1/G0 phase. The percentage of cells in G1/G0 phase in BGC823 cells with shRNA-NC and with shRNA-HMGB3 was 46.84% ± 1.7%, and 73.03% ± 3.51% respectively (P = 0.001), whereas G2/M cells percentage decreased from 26.51% ± 0.83% to 17.8% ± 2.26%. CONCLUSION: HMGB3 is likely to be a useful prognostic marker involved in gastric cancer disease onset and progression by regulating the cell cycle.

Surface modification of phenolphthalein poly(ether sulfone) ultrafiltration membranes by blending with acrylonitrile-based copolymer containing ionic groups for imparting surface electrical properties.

Asymmetric ultrafiltration membranes were fabricated from the blends of phenolphthalein polyethersulfone (PES-C) and acrylonitrile copolymers containing charged groups, poly(acrylonitrile-co-acrylamido methylpropane sulfonic acid) (PAN-co-AMPS). From the surface analysis by XPS and ATR-FTIR, it was found that the charged groups tend to accumulate onto the membrane surface. This result indicated that membrane surface modification for imparting surface electrical properties could be carried out by blending charged polymer. Furthermore, with the help of a relatively novel method to measure membrane conduction, the true zeta potentials calculated on the basis of the streaming potential measurements were used to reflect the charge state of membrane surface. In addition, it was noteworthy that, from the profiles of zeta potential versus pH curves and the magnitude of zeta potentials, the determination of zeta potential was dependent not only on the electrical properties of membrane surface but also on its hydrophilicity. At last, based on a relatively elaborate study on the electrostatic interaction between the membrane surface and protein, it was found that these charged membranes could meet different demands of membrane applications, such as resisting protein fouling or protein separation, through adjusting solution pH value.