60 research outputs found

    Red-Light-Responsive Supramolecular Valves for Photocontrolled Drug Release from Mesoporous Nanoparticles

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    Red-light-responsive supramolecular valves constructed by tetra-<i>ortho</i>-methoxy-substituted azobenzene (mAzo) and β-cyclodextrin (β-CD) were used to control drug release from mesoporous silica nanoparticles (MSNs). Doxorubicin (DOX) was used as a model drug and loaded into nanopores of mAzo modified MSNs. β-CD formed supramolecular valves with mAzo by host–guest interaction and closed the nanopores. Red light was able to open the supramolecular valves and induce DOX release even in deep tissue

    Complete Removal of Organic Contaminants from Hypersaline Wastewater by the Integrated Process of Powdered Activated Carbon Adsorption and Thermal Fenton Oxidation

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    The feasibility of reusing hypersaline wastewater containing a high concentration of organic contaminants by a combined process of powdered activated carbon (PAC) adsorption and Fenton oxidation was investigated in this study. Operating conditions of the integrated process were optimized by jar tests. According to the results of molecular weight (MW) and full wavelength scanning analysis, most of the aromatic compounds with high MW (>1000 Da) were removed after adsorption pretreatment, but the effects of PAC adsorption on hydrophilic organic pollutants of low MW were rather limited. The adsorption followed a pseudo-second-order kinetic equation. Additionally, the strategy for maximizing the efficiency of both H<sub>2</sub>O<sub>2</sub> and organic removal in saline wastewater was proposed. The Fenton efficiency was strongly dependent on both reaction conditions and feeding modes of reagents. Organic removal was significantly enhanced by slowing down the feeding rate of Fenton’s reagents. Moreover, rapid acidification of the wastewater was observed after adding a small amount of Fenton’s reagents, and the H<sub>2</sub>O<sub>2</sub> dosage required for achieving a sufficient organic removal (effluent total organic carbon (TOC) < 200 mg/L) decreased by 22.2% with pH 3.0 maintained throughout oxidation process. Under the optimal oxidation conditions (reaction temperature = 80–90 °C, pH = 3, Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub> molar ratio = 0.03), overall TOC removal efficiency of the integrated process was more than 95% of which 30% corresponds to the adsorption of PAC and 65% to the Fenton oxidation process. Furthermore, a pilot test indicated that the final effluent of the integrated process could conform to the standard for saline water recycle, confirming that this process provided a more economical and feasible alternative for reusing the hypersaline water contaminated with a high concentration of organic compounds

    Visible-Light-Responsive Azopolymers with Inhibited π–π Stacking Enable Fully Reversible Photopatterning

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    Photoswitchable polymers are promising candidates for information storage. However, two general problems for photoswitchable polymers used in rewritable optical storage are photobleaching and inefficient switching processes in solid state. To overcome both of these obstacles, we demonstrate the synthesis of a new visible-light-switchable azobenzene-containing polymer (azopolymer) with nonstackable azo chromophores for reversible and stable information storage. The new azopolymer (PmAzo) contains ortho-methoxy-substituted azobenzene (mAzo) groups on the polymer side chains and shows reversible trans-to-cis or cis-to-trans isomerization by using distinct wavelengths of visible light. PmAzo is better suited for reversible optical storage than conventional UV-responsive azopolymers because visible light avoids the photodamage caused by UV light. Additionally, mAzo groups do not π–π stack in solid state, making photopatterning of PmAzo fully reversible. Moreover, photoinduced patterns on PmAzo can be stored for more than half a year. These properties distinguish PmAzo as a promising candidate for rewritable and stable information storage

    Control-Oriented Modeling and Real-Time Control for the Ozone Dosing Process of Drinking Water Treatment

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    Ozonation is one of the most important steps during drinking water treatment. To improve the efficiency of ozonation and to stabilize the quality of the treated water, control-oriented modeling and a real-time control method for the ozone dosing process are developed in this study. Compared with existing ozonation models developed by bench-scale and pilot-scale batch experiments, the model reported herein is control-oriented and based on plant-scale batch experiments. A real-time control strategy for maintaining a constant ozone exposure is attempted to meet primary disinfection requirements. An internal model control scheme is proposed to maintain a constant ozone exposure by adjusting the ozone dosage. The proposed real-time control method can cope with changing water quality, water flow rate, and process operational conditions. Both simulations and experimental studies have been carried out and implemented for the ozone dosing process control system, and the results demonstrate the effectiveness and practicality of this real-time control method

    Petrogenesis and tectonic implications of early Palaeozoic igneous rocks of the western South Qilian Belt, central China

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    <p>Early Palaeozoic granitoids in the South Qilian Belt, central China, record details of the tectonic evolution and crustal growth of the Qilian orogenic belt. Five representative granitoids from the western South Qilian Belt were sampled for zircon LA-ICPMS U–Pb dating, Lu–Hf isotopes, and whole-rock geochemical analyses. Zircon U–Pb dating of two porphyritic granodiorites and a porphyritic monzogranite yielded ages of 442.7 ± 3.5, 441.8 ± 4.3, and 435.4 ± 3.5 Ma, respectively. These granitoids exhibit a geochemical affinity to I-type granite, are metaluminous with a low aluminium saturation index (A/CNK = 0.75–1.15), have moderate Al<sub>2</sub>O<sub>3</sub> and low MgO contents, high La/Yb and low Sr/Y ratios, and are depleted in Nb, Ta, P, and Ti, which suggests a subduction zone magmatic arc affinity, with mixing between a primary mantle-derived magma with lesser continental crustal material. The syenogranite and monzogranite from the South Qilian Belt, which yield U–Pb zircon ages of 440.4 ± 9.0 and 442.3 ± 1.2 Ma, respectively, have pronounced S-type geochemical affinities, are peraluminous with A/CNK values of 1.07–1.16, have relatively high SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, K<sub>2</sub>O, and Rb contents, low Y and Yb, low Sr/Y and La/Yb ratios, positive Th, U, and light Rare Earth Element (REE) anomalies, and depletions in Nb, Ta, Sr, and Ti. Their geochemical signature suggests derivation from partial melting of continental crust in a syn-collisional setting. The Hf isotopic data of zircons from the granitoids show a significant input of Paleoproterozoic crust in the crustal formation of the western South Qilian Belt in Palaeozoic. Compare the <i>ε</i><sub>Hf</sub>(<i>t</i>) value of S-type granite with that of I-type granite, the former may have a comparatively homogeneous source. Together with regional evidence, it is proposed that a collisional event occurred between the South Qilian Belt and the Central Qilian Belt at ca. 442–435 Ma.</p

    Phylogeny Reconstruction and Hybrid Analysis of <i>Populus</i> (Salicaceae) Based on Nucleotide Sequences of Multiple Single-Copy Nuclear Genes and Plastid Fragments

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    <div><p><i>Populus</i> (Salicaceae) is one of the most economically and ecologically important genera of forest trees. The complex reticulate evolution and lack of highly variable orthologous single-copy DNA markers have posed difficulties in resolving the phylogeny of this genus. Based on a large data set of nuclear and plastid DNA sequences, we reconstructed robust phylogeny of <i>Populus</i> using parsimony, maximum likelihood and Bayesian inference methods. The resulting phylogenetic trees showed better resolution at both inter- and intra-sectional level than previous studies. The results revealed that (1) the plastid-based phylogenetic tree resulted in two main clades, suggesting an early divergence of the maternal progenitors of <i>Populus</i>; (2) three advanced sections (<i>Populus</i>, <i>Aigeiros</i> and <i>Tacamahaca</i>) are of hybrid origin; (3) species of the section <i>Tacamahaca</i> could be divided into two major groups based on plastid and nuclear DNA data, suggesting a polyphyletic nature of the section; and (4) many species proved to be of hybrid origin based on the incongruence between plastid and nuclear DNA trees. Reticulate evolution may have played a significant role in the evolution history of <i>Populus</i> by facilitating rapid adaptive radiations into different environments.</p></div

    Phylogeny of <i>Populus</i> obtained from the combined 12 plastid fragments using parsimony method, (A).

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    <p>Numbers next to nodes sequentially indicated ML/parsimony/BI support values. The branches without numbers indicate 100% statistical support. (B) The topology difference derived from Bayesian analysis while (C) is from ML analysis. A, <i>Aigeiros</i>; L, <i>Leucoides</i>; P, <i>Populus</i>; Tac, <i>Tacamahaca</i>; Tur, <i>Turanga</i>.</p

    Phylogeny of Populus obtained from the combined 24 single-copy nuclear DNA sequences using ML method, (A).

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    <p>Numbers next to nodes sequentially indicate ML/parsimony/BI support values. The branches without numbers indicate 100% statistical support. (B) The topology difference derived from Bayesian analysis. A, <i>Aigeiros</i>; L, <i>Leucoides</i>; P, <i>Populus</i>; Tac, <i>Tacamahaca</i>; Tur, <i>Turanga</i>.</p

    Image2_Genome-wide identification, evolution and transcriptome analysis of GRAS gene family in Chinese chestnut (Castanea mollissima).TIF

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    GRAS transcription factors play an important role in regulating various biological processes in plant growth and development. However, their characterization and potential function are still vague in Chinese chestnut (Castanea mollissima), an important nut with rich nutrition and high economic value. In this study, 48 CmGRAS genes were identified in Chinese chestnut genome and phylogenetic analysis divided CmGRAS genes into nine subfamilies, and each of them has distinct conserved structure domain and features. Genomic organization revealed that CmGRAS tend to have a representative GRAS domain and fewer introns. Tandem duplication had the greatest contribution for the CmGRAS expansion based on the comparative genome analysis, and CmGRAS genes experienced strong purifying selection pressure based on the Ka/Ks. Gene expression analysis revealed some CmGRAS members with potential functions in bud development and ovule fertility. CmGRAS genes with more homologous relationships with reference species had more cis-acting elements and higher expression levels. Notably, the lack of DELLA domain in members of the DELLA subfamily may cause de functionalization, and the differences between the three-dimensional structures of them were exhibited. This comprehensive study provides theoretical and practical basis for future research on the evolution and function of GRAS gene family.</p
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