Xue, Wei
Zhang, Yang
Duan, Juanjuan
Liu, Dong
Ma, Yawei
Shi, Naien
Chen, Shufen
Xie, Linghai
Qian, Yan
Huang, Wei
Fluorescent polymer nanofibers have wide applications in the fields of nano-photonics, nanooptoelectronics, chemical sensors and light-emitting diodes. The doping of small fluorophores into low-cost polymers is a proven alternative route to produce cost-effective and high-performance optical materials. In order to gain deep insight into the photophysical processes of small molecule-doped polymer nanofiber systems and obtain highly sensitive and cost-effective explosive fluorescent sensors, a new type of highly sensitive low-cost sensor for nitro-compounds was synthesized based on PEO/MePyCz (polyethylene oxide/4-(2-(2-(2-methoxyethoxy) ethoxy) ethoxy)-9-(pyren-1-yl)-9H-carbazole) composite nanofibers. It exhibited fast response and high quenching efficiency towards DNT vapor, which may be attributed to an improved exciton migration of MePyCz in PEO in addition to the large driving force of the electron transfer and the nanofibrous structures. Additionally, it promoted a fluorescence resonance energy transfer process in the polymer fibrous matrix with a green-emitting material of 2-(thiophen-2-yl)-fluoren-9-one. The sensing composite nanofibrous film had good sensitivity and selectivity and might be constructed into a portable detector for explosives.
Xiao, Kui
Xue, Wei
Li, Zhaoliang
Wang, Jirui
Li, Xueming
Dong, Chaofang
Wu, Junsheng
Li, Xiaogang
Wei, Dan
In this paper, SiO2, Cr2O3, A1(2)O(3), and MgO were used as ceramic aggregates, and a small amount of Al powder was added A ceramic coating was prepared on a Q235 steel substrate The effect of the sintering temperature on the coating microstructure, phase structure and wear resistance was studied by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and friction and wear testing The results show that the tensile strength of the ceramic coating is increased after sintering, the structure becomes dense, and the size of coated micropores is increased to release the internal tensile stress. With the increase of the sintering temperature and tensile stress, the micropores begin to release the excess tensile stress in the form of crack initiation and expansion. The mineralization of MgO, Cr2O3, nMgO and mSiO(2) phases can be achieved by sintering the coating at 200 degrees C. the oxygen in the atmosphere migrates along the micropores in the coating to react with Fe in the steel substrate, forming FeO, and the resulting FeO reacts with the SiO2 the coating to form the Fe2SiO4 phase. The coating has the best wear resistance after being sintered at 400 degrees C, and the abrasion resistance of the sample is 6.7 times higher than that of the sample dried at room temperature.
Five new metal-carboxylate chain-based laminated compounds, namely, (2)(infinity)[Fe(II)(e,e-trans-1,2-chdc)] (3) (1,2-chdc = cyclohexane-1,2-dicarboxylate), (2)(infinity)[Ni(II)(mu-OH(2))(e,a-cis-1,2-chdc)] (4), (2)(infinity)[Co(II)(mu-OH(2))(1,2-chedc)] (5) (1,2-chedc = cyclohex-1-ene-1,2-dicarboxylate), (2)(infinity)[Co(5)(II)(mu(3)-OH)(2)(OH(2))(2)(1,2-chedc)(4)] (6), and (2)(infinity)[Co(II)(4-Me-1,2-chdc)] (7) (4-Me-1,2-chdc = = trans-4-methylcyclohexane-1,2-dicarboxylate) have been hydrothermally synthesized. In these series of magnetic chain-based compounds, 3 and 7 have the same dimeric paddle-wheel M(II)-carboxylate chain as the previously reported compound, (2)(infinity)[Co(II)(trans-1,2-chdc)] (2). However, compound 3 does not behave as a single-chain magnet (SCM) but simply an alternating ferro-antiferro magnetic chain. Compound 4 has the cis conformation of 1,2-chdc ligand, which leads to a uniform aqua-carboxylate-bridged Ni(II) chain. Such a Ni-O chain exhibits strong antiferromagnetic interactions, leading to a diamagnetic ground state. Compound 5 features a corner-sharing triangular chain, or A-chain, which is part of a Kagome lattice. However, 5 does not exhibit a spin-frustrated effect but simply spin competition. Compound 6 has a unique pentanuclear Coll cluster, which is further connected by the syn-anti carboxylate into a chain structure. Compound 6 exhibits antiferromagnetic interactions among the Co(II) ions, and no SCM behavior is observed. These results might indicate that the dimeric paddle-wheel Co(II)-carboxylate chain is essential in obtaining SCM behavior in this family of compounds. Although 2 and 7 have very similar SCM behavior, alternating current magnetic studies show that 7 has a higher energy barrier than that of 2. Such behavior is probably caused by the larger anisotropic energy barrier in 7.
Bioreducible polymers have appeared as the ideal drug carriers for tumor therapy due to their properties of high stability in extracellular circulation and rapid drug release in intracellular reducing environment. Recently, the diselenide bond has emerged as a new reduction-sensitive linkage. In this work, the amphiphilic poly(ethylene glycol)-b-poly(L-lactide) containing diselenide bond has been synthesized and used to load anti-tumor drug, docetaxel (DTX), to form the redox micelles. It was found that the redox micelles showed a rapid response to glutataione (GSH), which resulted in a fast release of DTX in the presence of GSH. In contrast, <40% of DTX was released from the micelles within 72h under the normal condition (absence of GSH). The DTX-loaded redox micelles showed the significant inhibition effect to MCF-7 cells, and the cytotoxicity was dependent on the intracellular GSH concentrations. Moreover, considering the potentially clinical applications of the micelles through intravenous injection, the blood compatibility was also studied by the hemolysis analysis, activated partial thromboplastin time, prothrombin time and thromboelastography assays. These results confirmed that the redox micelles showed good blood safety, suggesting a potential application in tumor therapy. =20
Climate models show a conspicuous summer warm and dry bias over the central United States. Using results from 19 climate models in the Coupled Model Intercomparison Project Phase 5 (CMIP5), we report a persistent dependence of warm bias on dry bias with the precipitation deficit leading the warm bias over this region. The precipitation deficit is associated with the widespread failure of models in capturing strong rainfall events in summer over the central U.S. A robust linear relationship between the projected warming and the present-day warm bias enables us to empirically correct future temperature projections. By the end of the 21st century under the RCP8.5 scenario, the corrections substantially narrow the intermodel spread of the projections and reduce the projected temperature by 2.5 K, resulting mainly from the removal of the warm bias. Instead of a sharp decrease, after this correction the projected precipitation is nearly neutral for all scenarios.
A flexible Zn-pyrazolate-carboxylate framework [Zn7O2(deppy)(2)(oba)(4)]center dot 2.5DMF center dot 2H(2)O (1) (Hdeppy = 3,5-diethyl-4-(4'-pyridyl)pyrazole, H(2)oba = 4,4'-oxobisbenzoic acid) was synthesized by solvothermal reaction. Single-crystal X-ray diffraction indicated that 1 possesses a 10-connected bct topological network based on a rare heptanuclear zinc(II) cluster. Comparison of crystal structures of 1 determined at 300 K and 150 K illustrated the conformational flexibility of deppy ligands. Thermogravimetry analyses and powder X-ray diffraction measurements showed that 1 has high thermal stability and good water stability. Gas and liquid sorption experiments of 1 not only showed stronger adsorption of CO2 compared with N-2, but also demonstrated highly efficient separation of n-propylbenzene from other C9H12 alkylbenzene isomers 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene.
Luo, Fang-Li
Huang, Lin
Lei, Ting
Xue, Wei
Li, Hong-Li
Yu, Fei-Hai
Cornelissen, Johannes H. C.
QuestionPlant trait mean values and trait responsiveness to different environmental regimes are both important determinants of plant field distribution, but the degree to which plant trait means vs trait responsiveness predict plant distribution has rarely been compared quantitatively. Because hydrological regime is a key determinant of wetland plant distribution, we hypothesized that both plant trait means and trait responsiveness to experimental submergence could predict plant adaptation to a wet or a dry part of hydrological gradients in wetlands. LocationBeijing, China. MethodsWe measured mean values for 14 plant traits by growing 30 wetland species both on land (control) and partially submerged in a greenhouse, and calculated log response ratios (LnRRs) of these traits to submergence. A distribution pattern index of wetland plants along the moisture gradient (from the zone furthest from the wetland waterline to that nearest to the waterline) was developed based on plant survey data in 3988 field plots in 24 wetlands in Beijing, China. ResultsLnRRs of performance traits (shoot biomass, root biomass, plant height and total root length; R-2=3D0.249, P=3D0.005) and one out of five morphological traits (i.e. shoot elongation capacity; R-2=3D0.194, P=3D0.015) between partially submerged and control treatments could predict the distribution pattern of the 30 wetland plant species. In contrast, means of plant traits in either control or submergence could not predict species distribution. The trait LnRRs, increasing from very negative to very positive, corresponded positively with the distribution, ranging from the zone furthest from the wetland waterline to that nearest to the waterline. Surprisingly, physiological trait LnRRs that had been expected to underpin performance trait LnRRs did not themselves predict the distribution pattern of these species. Analyses at the level of multivariate trait groups (based on PCA) showed that species LnRRs of the morphological trait group were positively correlated with LnRRs of the performance trait group. ConclusionsOur findings demonstrate that screening wetland plant species for performance and morphological trait LnRRs under experimentally flooded conditions is an effective approach to understand and predict their distribution pattern along moisture gradients in the field.