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Ion exchange membranes (IEMs) have been extensively investigated as diaphragm materials for vanadium flow batteries (VFBs). However, current IEMs made of polymers still encounter challenges in ion selectivity (trade-off between ionic conductivity and vanadium resistance) and long-term stability (mechanical durability and chemical stability). Herein, fluorinated poly(aryl piperidinium) (PFDP) membranes without ether bonds are proposed to address these dilemmas. Microphase separation channels enriched with quaternary ammonium groups allow acceleration of ion transport while effectively rejecting vanadium ions. The ether-free polymer backbone and fluorinated structure can synergistically improve the stability of the IEM. The results indicate that the prepared PFDP membranes possess both excellent ion selectivity and stability, such as area resistance up to 0.17 Ω cm2, low vanadium permeability (<1.4 × 10−8 cm2 min−1) and dimensional swelling (swelling ratio < 8% in the electrolyte), high tensile strength (∼60 MPa) and chemical stability (>28 days in the antioxidant test). Benefiting from these advantages, the single-cell assembled with PFDP-90 has a high efficiency at 120 mA cm−2, especially the excellent energy efficiency (up to 84.3%), as well as shows stable cycling over 1000 cycles at 120 mA cm−2. This work provides new insights into advanced diaphragm materials at the molecular level. [ABSTRACT FROM AUTHOR]

Drug resistance caused by facultative intracellular bacteria such as Salmonella typhimurium (S. typhimurium) is still a tough challenge. Bacteria phagocytosed by macrophages have evolved a variety of mechanisms to defend against host attack, and the poor entry of antibiotics into infected macrophages is conducive to the survival of intracellular bacteria. In this report, we prepared a quasi-opsonized chloramphenicol (Chl)-loaded micellar system (B-mLBP-M/Chl) assembled by a bacterial lipase-sensitive polymer with a conjugate of lipopolysaccharide-binding protein (LBP) analog and biotin (B) as a ligand, which could eliminate drug-resistant S. typhimurium with quasi-opsonization via 3 steps: (i) target and release antibiotics on bacteria lipase, (ii) opsonize S. typhimurium to be digested by the macrophage, and (iii) activate the macrophage for fighting. The B-mLBP-M/Chl could target bacterial LPS through mLBP by simulating the N-terminal sequence of native LBP, exhibiting a high ability to target the localized infection site in mice. It could also activate the phagocytosis of macrophages via coupled biotin, cooperating with antibiotics and effectively improving the survival of mice with little pathological damage to tissues. Moreover, compared with native opsonin, B-mLBP does not cause an excessive inflammatory response and could recover homeostasis after exerting the quasi-opsonization by regulating the levels of pro-inflammatory cytokines and anti-inflammatory cytokines. With a universal target site for Gram-negative bacteria and macrophage activation, this B-mLBP-M/Chl could be applied to other bacterial infections in the future. In particular, this analog may also serve as a useful template to design safe artificial opsonin, which could be a ligand for drug delivery systems or prodrugs. [ABSTRACT FROM AUTHOR]

The power conversion efficiency (PCE) and operation stability of all-polymer solar cells (all-PSCs) are expected to be simultaneously pushed to a high level, that can be considered for further commercialization. Here the sequential processing (SqP) method is applied to process the PM6:PY-DT all-polymer system, while the control devices are made from the blend casting (BC) method. As a result, the efficiency rises to 16.5% in SqP devices from 15.8% of their BC counterparts, which is mainly caused by the improved fill factor (FF). Device physics study and morphology analysis reveal that optimized crystallinity and vertical phase separation result in suppressed charge recombination, higher charge collection and transport ability, which is responsible for PV performance improvement. In addition, operational stability is compared by maximal power point (MPP) tracking: the SqP device has a significantly longer time it takes to degrade to 80% of its initial PCE than the BC device, which could be attributed to the vertical composition distribution optimization realized by the two-step coating method. This work successfully demonstrates the effectiveness and promising future of using an SqP method to boost device performance for all-PSCs. [ABSTRACT FROM AUTHOR]

In this study, the kinetics of arsenite (As(III)) removal in a ferrihydrite/oxalate system under irradiation was investigated, and the effects of pH, ferrihydrite dosage, As(III) initial concentration, and oxalate concentration were evaluated. Ultraviolet A (UVA) irradiation significantly promoted As(III) removal in the presence of ferrihydrite and oxalate. The greatest removal efficiency of As(III) (92.5%) was observed under the following conditions: pH 3.0, 100.0 μg L−1 As(III), 0.0125 g L−1 ferrihydrite, 0.1 mmol L−1 oxalate, and after 90 min under UVA irradiation. The removal of As(III) in the ferrihydrite/oxalate system was strongly pH-dependent. Mechanistic investigations indicated that HO˙ was the primary oxidant for As(III) photo-oxidation in the ferrihydrite/oxalate system. Surface adsorbed hydroxyl radical (HOads˙) was the dominant oxidant over the entire pH range in the presence of oxalate, and the hydroxyl radical in aqueous solution (HOaq˙) made only a small contribution under acidic conditions. The sources of HO˙ were also strongly dependent on pH; HO2˙/O2˙− was the precursor of HO˙ under acidic conditions, while photo-generated holes gradually became the main source of HO˙ as the pH increased. The photo-oxidation of As(III) mainly occurred on the surface of ferrihydrite. Although some ferrihydrite transformed into goethite during the removal process, the iron oxides showed good reusability for up to five regeneration cycles. The findings indicate that As(III) can be efficiently removed by the ferrihydrite/oxalate system and provide guidance for developing effective treatment strategies for As(III)-contaminated waters. [ABSTRACT FROM AUTHOR]

In this work, carbon dots-decorated hydroxyapatite nanowires–lanthanide metal–organic framework composites were designed and synthesized as ratiometric fluorescent probes for the detection of dopamine. The as-prepared HAPNWs-CDs-Tb/MOF were characterized by TEM, FE-SEM, and FT-IR spectral analysis, illustrating that the HAPNWs-CDs-Tb/MOF comprised hydroxyapatite nanowires that acted as a carrier to form a spinning structure of the lanthanide MOF that was decorated with carbon dots. The as-prepared HAPNWs-CDs-Tb/MOF were luminescent with the green fluorescence of Tb3+ at 543 nm and the blue fluorescence of the CDs at 426 nm as the signal response groups for the detection of DA. The sensor could detect DA in the concentration range of 0–180 μM, with a linear range of 0.04–20 μM and detection limit of 12.26 nM. The method was successfully applied to the detection of DA in human serum. The spiked recoveries were 100.8%–103.3% and the relative standard deviation (RSD) was 3.82%. [ABSTRACT FROM AUTHOR]

Color-tunable long persistent luminescence (LPL) phosphors are more strongly desired for intelligent anti-counterfeiting and information storage compared with single color types. Herein, BaGa2O4 (BGO): x% Pr3+, y% Zn2+ (0.005 ≤ x ≤ 1.0, 0.5 ≤ y ≤ 3.0) are synthesized using a simple solid-state method and its crystal structure, optical performances, and trap properties are discussed in detail. The structure refinement implies Pr3+ and Zn2+ occupy Ba2+ and Ga3+ sites respectively, which lead to cell expansion along the c-axis and could be conducive to generating the defects such as oxygen vacancy , and. Spectrum analyzation shows that due to energy transfer from host luminescence to Pr3+ and its cross-relaxation, the PL shows color-tunable (blue to white even to red) emission. The addition of Zn2+ can enhance the host-defect luminescence range of 400–550 nm closely related to and the change in band gaps. Thus, the optimal LPL sample, BGO: 0.6% Pr3+, 2.0% Zn2+ (initial brightness: ∼0.256 cd m−2, LPL decay time: ∼3500 s), is obtained. Moreover, based on DFT calculation, can be easily generated with the formation energy of 5.75 eV. In addition, the effect of is further studied by thermal-luminescence curve (TL), X-ray photoelectron spectroscopy (XPS) and electron spin resonance spectroscopy (ESR). According to the results, a possible LPL mechanism is proposed, and the dynamic multi-color pieces are designed for anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The pressure-induced phase transition and polymerization of nitrogen-rich molecules are widely focused on due to their extreme importance for the development of green high-energy-density materials. Here, we present a study of the phase-transition behaviour and chemical reaction of 1H-tetrazole up to 100 GPa using in situ Raman, IR, X-ray diffraction, neutron diffraction techniques and theoretical calculations. A phase transition above 2.6 GPa was identified and the high-pressure structure was determined with one molecule in a unit cell instead of two molecules as reported before. The 1H-tetrazole polymerized reversibly below 100 GPa, probably through carbon–nitrogen bonding instead of nitrogen–nitrogen bonding. Our studies update the structure model of the high-pressure phase of 1H-tetrazole, and present the possible intermolecular bonding route for the first time, which gives new insights to understand the phase transition and chemical reaction of nitrogen-rich compounds, and is of benefit for designing new high-energy-density materials. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction is promising for reducing the greenhouse effect and producing renewable energy, but still shows low activity and selectivity due to the ineffective utilization of photogenerated charge carriers and insufficient active sites for CO2 adsorption and activation. Taking CdS nanocrystals as a model semiconductor, we demonstrate that graphdiyne, a new type of two-dimensional carbon allotrope uniquely formed from sp- and sp2-hybridized carbon, enhances CO2 photoreduction over CdS with higher activity, selectivity, and stability in the gas phase without any sacrificial agent compared to graphene. Both experimental and theoretical results prove that the chemical bonding between graphdiyne and CdS and sufficient CO2 adsorption sites due to the strong interfacial interaction-induced sulfur vacancies in CdS and more electron-deficient acetylenic linkages in graphdiyne lead to more efficient electron transfer and storage for the subsequent CO2 reduction reaction. The excellent properties of graphdiyne make it promising for applications in solar energy conversion. [ABSTRACT FROM AUTHOR]

Dextranase is a unique biocatalyst for the enzymatic hydrolysis of dextran in carbohydrate chemistry, but the instability and poor recycling ability of dextranase significantly limit its long-term applications. As an alternative method, stabilization of dextranase on a solid carrier is a promising strategy. In this study, a kind of polyethylenimine (PEI) polymer modified magnetic particle was fabricated and employed as the substrate for covalent immobilization of dextranase (Fe3O4@SiO2-PEI-dextranase) to improve the stability and reusability performance for the first time. The grafted PEI polymer on the surface enhanced the amount of primary amine groups, and improved the loading capacity of dextranase on Fe3O4@SiO2-PEI-dextranase to 217.2 mg g−1, which was 3.84 times that measured on Fe3O4@SiO2-NH2-dextranase particles. Under the optimized conditions, high immobilization efficiency (72.38%) and enzymatic activity (82.84%) of Fe3O4@SiO2-PEI-dextranase were achieved. Thermal and pH tolerance, and long-term storage tests revealed that the Fe3O4@SiO2-PEI-dextranase exhibited much better stabilities. More importantly, Fe3O4@SiO2-PEI-dextranase retained 83.26% of its initial activity after reuse 15 times, suggesting its excellent reusability. It is believed that the immobilized dextranase could have potential applications in biological and biocatalytic fields. [ABSTRACT FROM AUTHOR]

Covering up to end 2015 Microbial fermentation provides an attractive alternative to chemical synthesis for the production of structurally complex natural products. In most cases, however, production titers are low and need to be improved for compound characterization and/or commercial production. Owing to advances in functional genomics and genetic engineering technologies, microbial hosts can be engineered to overproduce a desired natural product, greatly accelerating the traditionally time-consuming strain improvement process. This review covers recent developments and challenges in the engineering of native and heterologous microbial hosts for the production of bacterial natural products, focusing on the genetic tools and strategies for strain improvement. Special emphasis is placed on bioactive secondary metabolites from actinomycetes. The considerations for the choice of host systems will also be discussed in this review. [ABSTRACT FROM AUTHOR]

Gel formation by an N-fluorenyl-9-methoxycarbonyl (Fmoc)-based molecule was investigated and the chirality amplification observed during the self-assembly process could be switched on and off by controlling the solvent environment. The molecules could form gel in mixed solvents of water and dimethyl sulfoxide (DMSO) at either a high water fraction to afford flat nanofibers or a low water fraction to generate nanofibers with supramolecular chirality. At a moderate fraction of water, the molecules self-assemble into a precipitate composed of nanosheets. Furthermore, the gels showed different mechanical properties and thermal stabilities. Mechanism studies showed that π–π stacking interactions between the aromatic Fmoc groups and hydrogen bondings between the amide groups played important roles in the self-assembly process of the different gels. This study strives to shed light on the tuning of chiral gels with various nanostructures via controlled self-assembly, which might have potential use in smart materials. [ABSTRACT FROM AUTHOR]

A new morphology of TiO2 photoanodes for N-719 dye-sensitized solar cells (DSCs) has been developed with enhanced power conversion performance. Strategies for the synthesis of hierarchically structured three-dimensionally ordered macroporous (HS-3DOM) TiO2 with controlled macropore sizes (ca. 85–155 nm) by using well-arrayed polymethyl methacrylate with different diameters as well as two kinds of photoanode films based on hierarchically structured porous TiO2 filled with nanoparticles have been demonstrated. DSCs based on a special TiO2 photoanode with a macropore size of 105 nm exhibited a current density (Jsc) of 20.6 mA cm−2 and a high photo-to-electrical energy conversion efficiency (η) of 9.7%. This high power conversion efficiency is ascribed to the special morphology of the TiO2 photoanode with high dye adsorption due to its ordered and open structures, and also its light scattering and charge collection efficiency. [ABSTRACT FROM AUTHOR]

Quantum dot sensitized solar cells (QDSCs) have attracted considerable attention recently and become promising candidates for realizing a cost-effective solar cell. The design and synthesis of quantum dots (QDs) for achieving high photoelectric performance is an urgent need imposed on scientists. Here, we have succeeded in designing a QDSC with a high efficiency η of 6.33% based on Cd0.8Mn0.2Se quantum dots by facile chemical bath deposition (CBD). The effects of Mn2+ ions on the physical, chemical, and photovoltaic properties of the QDSCs are investigated. The Mn2+ ions doped into QDs can increase the light harvesting to produce more excitons. In addition, the Mn2+ dopant also raises the conduction band of CdSe, accelerates the electron injection kinetics and reduces the charge recombination, improving the charge transfer and collection. The increase of the efficiencies of light-harvesting, charge-transfer and charge-collection results in the improvement of the quantum efficiency of the solar cells. The power conversion efficiency of the solar cell is increased to 6.33% (Voc = 0.58 V, Jsc = 19.15 mA cm−2, and FF = 0.57). [ABSTRACT FROM AUTHOR]

A high purity α-layered sodium disilicate (α-Na2Si2O5) has been synthesized by employing a mixture of 84% α-Na2Si2O5and 16% δ-Na2Si2O5as seed, and characterized by XRD, 29Si MAS NMR, FT-IR, SEM and TG. The experimental data showed that α-layered sodium disilicate may been synthesized by adding 15% seed at 780 °C for 120 minutes. The lubrication of the synthesized sample was investigated. Adding α-Na2Si2O5in liquid paraffin, the PBvalue increased by 19.9%. The results indicated that oleic acid may pillar α-layered sodium disilicate. The reaction may increase the separation of layers. An increasing layer distance will be propitious for the glide of silicon layers and improve lubrication ability. [ABSTRACT FROM AUTHOR]

Transformation between different types of carbon-carbon bonding in carbides often results in a dramatic change of physical and chemical properties. Under external pressure, unsaturated carbon atoms form new covalent bonds regardless of the electrostatic repulsion. It was predicted that calcium acetylide (also known as calcium carbide, CaC 2 ) polymerizes to form calcium polyacetylide, calcium polyacenide and calcium graphenide under high pressure. In this work, the phase transitions of CaC 2 under external pressure were systematically investigated, and the amorphous phase was studied in detail for the first time. Polycarbide anions like C 6 6- are identified with gas chromatography-mass spectrometry and several other techniques, which evidences the pressure induced polymerization of the acetylide anions and suggests the existence of the polyacenide fragment. Additionally, the process of polymerization is accompanied with a 10 7 fold enhancement of the electrical conductivity. The polymerization of acetylide anions demonstrates that high pressure compression is a viable route to synthesize novel metal polycarbides and materials with extended carbon networks, while shedding light on the synthesis of more complicated metal organics.