Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Mais filtros

Base de dados
Intervalo de ano de publicação
Environ Sci Technol ; 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32108470


Redox-active organic molecules such as anthraquinone-2,6-disulfonate (AQDS) and natural organic matter (NOM) can act as electron shuttles thus facilitating electron transfer from Fe(III)-reducing bacteria (FeRB) to terminal electron acceptors such as Fe(III) minerals. In this research, we examined the length scale over which this electron shuttling can occur. We present results from agar-solidified experimental incubations, containing either AQDS or NOM, where FeRB were physically separated from ferrihydrite or goethite by 2 cm. Iron speciation and concentration measurements coupled to a diffusion-reaction model highlighted clearly Fe(III) reduction in the presence of electron shuttles, independent of the type of FeRB. Based on our fitted model, the rate of ferrihydrite reduction increased from 0.07 to 0.19 µmol d-1 with a 10-fold increase in the AQDS concentration, highlighting a dependence of the reduction rate on the electron-shuttle concentration. To capture the kinetics of Fe(II) production, the effective AQDS diffusion coefficient had to be increased by a factor of 9.4. Thus, we postulate that the 2 cm electron transfer was enabled by a combination of AQDS molecular diffusion and an electron hopping contribution from reduced to oxidized AQDS molecules. Our results demonstrate that AQDS and NOM can drive microbial Fe(III) reduction across 2 cm distances and shed light on the electron transfer process in natural anoxic environments.

Chin Med J (Engl) ; 133(5): 552-560, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32044815


BACKGROUND: After neoadjuvant chemotherapy (NAC), non-pathological complete response of breast cancer patients can benefit from tailored adjuvant chemotherapy. However, it is difficult to select patients with poorer prognosis for additional adjuvant chemotherapy to maximize the benefits. Our study aimed to explore whether the subtypes of tumor-infiltrating lymphocytes (TILs) in residual tumors (RT) is related to the prognosis of triple-negative breast cancer (TNBC) after NAC. METHODS: Data from patients with primary TNBC consecutively diagnosed at the Breast Disease Center of Peking University First Hospital from 2008 to 2014 were retrieved, and the cases with RT in the breast after NAC were enrolled. TILs subtypes in RT were observed by double-staining immunohistochemistry, and counted with the median TILs value per square millimeter as the cut-off to define high versus low TILs density in each subtype. The relationships between the TIL density of each subgroup and the clinicopathological characteristics of the RT after NAC patients were analyzed by Fisher exact test. Disease-free survival (DFS) and overall survival (OS) were analyzed by the Kaplan-Meier method and log-rank statistics. RESULTS: A total of 37 eligible patients were included in this study, and the median follow-up period was 50 months (range 17-106 months). There was no significant correlation between the infiltrate density of CD4, CD8, CD20, and CD68 lymphocytes and clinic-pathological characteristics. Significantly better prognosis was observed in patients with high CD4-TILs (DFS: P = 0.005, OS: P = 0.021) and high CD8-TILs (DFS: P = 0.018) and low CD20-TILs (OS: P = 0.042). Further analysis showed that patients with CD4/CD20 ratio greater than 1 (DFS: P = 0.001, OS: P = 0.002) or CD8/CD20 ratio greater than 1 (DFS: P = 0.009, OS: P = 0.022) had a better prognosis. CONCLUSIONS: Subtypes of TILs in RT is a potential predictive biomarker of survival in TNBC patients after NAC.

ACS Appl Mater Interfaces ; 12(3): 3610-3616, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31891251


A porous polyimide (PI) membrane is successfully prepared via nonsolvent-induced phase separation with two porogens: dibutyl phthalate and glycerin. The as-prepared uniform porous PI membrane shows excellent separator properties for lithium-ion batteries (LIBs). Compared with the commercial polyethylene (PE) separator, the PI separator exhibits significant thermal stability, better ionic conductivity, and wettability both in carbonate and ether electrolytes for LIBs. The battery coin-cells assembled with the PI separator is more robust and still works even after heating at 140 °C for 1 h, while the cells with the commercial PE separator could not charge any more due to the shrinkage of the PE under the same condition.

Chemosphere ; 176: 255-265, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28273533


The fate and toxicity of zinc oxide nanoparticles (ZnO NPs) in nature are affected by solution chemistry such as pH, anions, and natural organic matter (NOM). Inorganic polyphosphates are environmentally ubiquitous phosphorus (P) species that may change the speciation and environmental fate of ZnO NPs. In this study, the interactions of polyphosphates with ZnO NPs and the impacts on ZnO NP dissolution and transformation were investigated and compared with orthophosphate (P1). The results revealed that pyrophosphate (P2), tripolyphosphate (P3), and hexametaphosphate (P6) enhanced whereas P1 inhibited the dissolution of ZnO NPs. In addition, P1, P2, and P3 promoted the transformation of ZnO NPs into zinc phosphate (Zn-P) precipitates via interactions with dissolved Zn2+. However, P6-promoted ZnO NP dissolution was through the formation of soluble Zn-P complexes due to the strong capability of P6 to chelate with Zn2+. The transformation of ZnO NPs in the presence of P3 was affected by reaction time, pH, and P/Zn molar ratio. P3 first formed inner-sphere surface complexes on ZnO NPs, which gradually transformed into crystalline Zn2HP3O10(H2O)6 precipitates. This study provided a new perspective for understanding the reactivity of various forms of inorganic phosphate species with ZnO NPs in the natural environment.

Precipitação Química , Nanopartículas/química , Fosfatos/química , Polifosfatos/química , Óxido de Zinco/química , Solubilidade , Compostos de Zinco