Magnetic Fe3O4@poly(m-phenylenediamine) particles (Fe3O4@PmPDs) with well-defined core-shell structure were first designed for high performance Cr(VI) removal by taking advantages of the easy separation property of magnetic nanoparticles (MNPs) and the satisfactory adsorption property of polymers. Through controlling the polymerization on MNPs, directly coating was realized without the complicated premodification procedures. The particle property and adsorption mechanism were analyzed in details. Fe3O4@PmPDs exhibited tunable PmPD shell thickness from 10 to 100 nm, high magnetic (∼150 to ∼73 emu g(-1)) and facile separation property by magnet. The coating of PmPD significantly enhanced Cr(VI) adsorption capacity from 46.79 (bare MNPs) to 246.09 mg g(-1) (71.55% PmPD loading proportion), much higher than many reported composite adsorbents. The high Cr(VI) removal performance was attributed to the adsorption of Cr(VI) on protonated imino groups and the efficient reduction of Cr(VI) to Cr(III) by amine, followed by Cr(III) chelated on imino groups, which are spontaneous and endothermic. The Fe3O4@PmPDs have great potential in treating Cr(VI)-contaminated water.

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Cephalotaxus oliveri is an endangered tertiary relict conifer endemic to China. The species survives in a wide range from west to east with heterogeneous climatic conditions. Precipitation and temperature are main restrictive factors for distribution of C. oliveri. In order to comprehend the mechanism of adaptive evolution to climate variation, we employed ISSR markers to detect adaptive evolution loci, to identify the association between variation in temperature and precipitation and adaptive loci, and to investigate the genetic structure for 22 C. oliveri natural populations. In total, 14 outlier loci were identified, of which five were associated with temperature and precipitation. Among outlier loci, linkage disequilibrium (LD) was high (42.86%), which also provided strong evidence for selection. In addition, C. oliveri possessed high genetic variation (93.31%) and population differentiation, which may provide raw material to evolution and accelerate local adaptation, respectively. Ecological niche modeling showed that global warming will cause a shift for populations of C. oliveri from south to north with a shrinkage of southern areas. Our results contribute to understand the potential response of conifers to climatic changes, and provide new insights for conifer resource management and conservation strategies.

Facile filling of multiwalled carbon nanotubes (MWCNTs) with Prussian blue nanoparticles (PBNPs) of high peroxidase-like catalytic activity was performed to develop novel colorimetric sensing protocols for assaying H2O2 and glucose. Fine control of PBNP growth was achieved by modulating the concentration ratio of K3 [Fe(CN)6] and FeSO4 precursors in an acidic solution containing ultrasonically dispersed MWCNTs, and thus size-matched PBNPs could be robustly immobilized in the cavities of the MWCNTs (MWCNT-PBin). Unlike other reported methods involving complicated procedures and rigorous preparation/separation conditions, this mild one-pot filling method has advantages of easy isolation of final products by centrifugation, good retention of the pristine outer surface of the MWCNT shell, and satisfactory filling yield of (24±2) %. In particular, encapsulation of PBNPs of poor dispersibility and limited functionality in dispersible and multifunctional MWCNT shells creates new and valuable opportunities for quasihomogeneous-phase applications of PB in liquid solutions. The MWCNT-PBin nanocomposites were exploited as a peroxidase mimic for the colorimetric assay of H2O2 in solution by using 3,3',5,5'-tetramethylbenzidine (TMB) as reporter, and they gave a linear absorbance response from 1 μM to 1.5 mM with a limit of detection (LOD) of 100 nM. Moreover, glucose oxidase (GOx) was anchored on the outer surface of MWCNT-PBin to form GOx/MWCNT-PBin bionanocomposites. The cooperation of outer-surface biocatalysis with peroxidase-like catalysis of interior PB resulted in a novel cooperative colorimetric biosensing mode for glucose assay. The use of GOx/MWCNT-PBin for colorimetric biosensing of glucose gave a linear absorbance response from 1 μM to 1.0 mM and an LOD of 200 nM. The presented protocols may be extended to other multifunctional nanocomposite systems for broad applications in catalysis and biotechnology.

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Background The floating population serves an important role in economic and social development. However, little is known about the floating population’s reproductive health (RH) services, especially in low- and middle-income countries. This study aimed to assess the use of reproductive health services in the female floating population in China, which is a country with the largest floating population in the world. Methods A cross-sectional survey was conducted for more than 3 months. Six hundred twenty females of childbearing age in a floating population were recruited into the study by using random sampling, with these individuals being recruited from six community centres in Changsha, China. The use of reproductive health services was assessed by utilizing a self-designed questionnaire. Results A total of 555 participants returned the completed questionnaires (effective response rate of 89.5%), including 405 married women and 150 unmarried women. The utilization of RH services was poor in individuals who could access RH policies (39.3%), RH education (36.4%), RH counselling (27.4%), gratis contraceptives (36.0%), and free RH examinations (38.9%), and married women utilized these services at higher rates than unmarried women ( P < 0.01), although 63.3% of the unmarried women had sexual lifestyles. The marital status was significantly associated with receiving RH education, RH counselling, gratis contraceptives, and free RH examinations. Age was significantly associated with the use of RH education and free RH examinations. The average personal monthly income had a significantly beneficial effect on the use of free RH examinations. Obstetrics and gynaecological disease prevention (67.2%) were the greatest needs of the RH services, and the use of the Internet was the best way to obtain these services. Most of the individuals (77.3%) hoped to receive gynaecological health screenings that were provided by obstetrics and gynaecology hospitals. Conclusions The female floating population exhibited poor awareness of RH and rarely used RH services, especially in unmarried women. The results suggest that educational interventions for the female floating population, as well as policy and resource developments should meet the demands for RH services, which are urgently needed in China. Electronic supplementary material The online version of this article (10.1186/s12913-019-4334-4) contains supplementary material, which is available to authorized users.

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