Portable hydroxyl-functionalized coal gangue-based cordierite porous ceramics sheets for effective adsorption of fluorine-containing wastewater.

Monolithic adsorbent removal of fluoride from water is considered an effective and non-secondary pollution method. Here, a portable hydroxyl-functionalized coal gangue-based cordierite porous ceramic sheet (ACGC-Fe) is prepared by using coal gangue solid waste with a specific silicon-aluminum-rich composition ratio and a small amount of magnesium oxide as a raw material through powder compression molding and mild chemical modification. The prepared ACGC-Fe can be used to treat fluorine-containing wastewater and the maximum adsorption of fluorine can reach 18.69 mg g-1. The Langmuir (Freundlich) adsorption isotherm model and pseudo-second-order kinetic model here provided a satisfactory description of the fluoride removal operating mechanism, and it is confirmed that the adsorption mechanism of ACGC-Fe is mainly attributed to the chemisorption of hydrogen bonds (with hydroxyl group) and ionic bonds (with metal), and physical adsorption based on cordierite porous ceramic pores. This research will provide a new idea for designing high-performance materials by mining and analyzing the composition and structure characteristics of coal gangue solid waste itself and broaden the application range of high-value-added coal gangue solid waste.

Aquaporin ZmTIP2;3 Promotes Drought Resistance of Maize through Symbiosis with Arbuscular Mycorrhizal Fungi.

Arbuscular mycorrhizal fungi symbiosis plays important roles in enhancing plant tolerance to biotic and abiotic stresses. Aquaporins have also been linked to improved drought tolerance in plants and the regulation of water transport. However, the mechanisms that underlie this association remain to be further explored. In this study, we found that arbuscular mycorrhiza fungi symbiosis could induce the gene expression of the aquaporin ZmTIP2;3 in maize roots. Moreover, compared with the wild-type plants, the maize zmtip2;3 mutant also showed a lower total biomass, colonization rate, relative water content, and POD and SOD activities after arbuscular mycorrhiza fungi symbiosis under drought stress. qRT-PCR assays revealed reduced expression levels of stress genes including LEA3, P5CS4, and NECD1 in the maize zmtip2;3 mutant. Taken together, these data suggest that ZmTIP2;3 plays an important role in promoting maize tolerance to drought stress during arbuscular mycorrhiza fungi symbiosis.

Influence of friction on the packing efficiency and short-to-intermediate range structure of hard-sphere systems.

Using particle-resolved computer simulations, we investigate the effect of friction on the packing structure of hard-sphere mixtures with two kinds of particles under external compression. We first show that increasing friction between the particles results in a more disordered and less efficient packing of the local structure on the nearest neighbor scale. It is also found that standard two-point correlation functions, i.e., radial distribution function and static structure factor, show basically no detectable changes beyond short-range distances upon varying inter-particle friction. Further analysis of the structure using a four-point correlation method reveals that these systems have on the intermediate-range scale a three-dimensional structure with an icosahedral/dodecahedral symmetry that exhibits a pronounced dependence on friction: small friction gives rise to an orientational order that extends to larger distances. Our results also demonstrate that composition plays a role in that the degree of structural order and the structural correlation length are mainly affected by the friction coefficients associated with the more abundant species.

Effect of modification by maltogenic amylase and branching enzyme on the structural and physicochemical properties of sweet potato starch.

Sweet potato starch (SPSt) was treated sequentially with the combination of maltogenic amylase (MA) and branching enzyme (BE) (MA â†’ BE) or BE and MA (BE→MA) to modify its structural and physicochemical properties. Following the MA â†’ BE and BE→MA modifications, the degree of branching was increased from 12.02 % to 44.06 %; whereas, the average chain length (ACL) decreased from 18.02 to 12.32. Fourier-transform infrared spectroscopy and digestive performance analysis indicated that the modifications reduced hydrogen bonds and increased resistant starch in SPSt. Rheological analysis revealed that the storage and loss moduli of the modified samples were lower than those of the control samples, except for starch treated with MA alone. X-ray diffraction measurements suggested that the re-crystallisation peak intensities of the enzyme-modified starches were lower than those of the untreated sample. The retrogradation resistance ability of the analysed samples followed the order: BE→MA-starches > MA â†’ BE-starches > untreated starch. The relationship between the crystallisation rate constant and short branched chains (DP6-9) was well described by linear regression. This study provides a theoretical foundation for retarding the retrogradation of starch, which can improve food quality and extend the shelf-life of enzymatically modified starchy foods.

Single-polymer dynamics of starch-like branched ring polymers in steady shear flow.

The stretching dynamics and dynamical behaviors of individual branched ring polymer (BRP), a coarse-grained model for some types of the starch, in steady shear flow are studied by using a hybrid mesoscale simulation approach that combines multiparticle collision dynamics with standard molecular dynamics. By analyzing the stretched configuration of BRPs, we find the polymer size increases nonmonotonically with increasing branch length. Meanwhile, the decrease of the alignment angle of the stretched configuration of BRPs follows a universal power law during the first downward phase as the shear rate increases. Constructing the three-dimensional surface of the polymer's ring backbone and tracing the temporal fluctuations of the surface's normal vector along the simulation trajectory, the tumbling and tank-treading motion are clearly reflected by periodic and non-periodic changes of the normal vector. Interestingly, these temporal changes are much more regular than that of the gyration tensor. Thus, a novel cross-correlation function, which is the correlation between fluctuations of the normal vector along the flow direction and the velocity-gradient direction, is proposed to analyze the tumbling motion that usually coexists with the tank-treading motion. This function can naturally address the fails of traditional method that analyzing the tumbling motion by determining the correlation of temporal fluctuations of the gyration tensor Gαα. By analyzing the dynamical behaviors of BRPs, diverse dependences of the tumbling frequency ωTB and tank-treading frequency ωTT on the shear rate γ̇ are observed at a wide range of shear rates and polymer sizes. Furthermore, our simulations also reveal that the tank-treading motion is more stable than the tumbling motion for small-branch-size BRPs but the tumbling motion is more stable than the tank-treading motion for large-branch-size BRPs.

Correlation between chain structures of corn starch and properties of its film prepared at different degrees of disorganization.

This study investigated the relationship between the chain structure of corn starch and the properties of corn starch-based films formed with starch pastes with different degrees of disorganization (70, 80, and 90 °C). The degree of gelatinization, chain length distribution, amylose content, and molecular weight of the corn starch were determined by the water absorption index, ion chromatography, spectrophotometry, and gel chromatography, respectively. The thickness, surface roughness, solubility, water content, water vapor permeability, mechanical properties, and maximum thermal degradation rate of corn starch-based films formed with starch pastes with different degrees of disorganization were evaluated. The moisture content, thickness and surface roughness of films formed with the starch pastes decreased. At the same time, the solubility, elongation at break, water vapor permeability, and molecular weight distribution increased with increasing heat treatment temperature. The maximum thermal degradation rate and tensile strength of the corn starch-based films formed with the starch pastes decreased with increasing heat treatment temperature. The gradual decrease in the amylose content of corn starch-based films formed with starch paste with increasing heat treatment temperature led to a change in the performance of the corn starch-based films.

Chiral three-dimensional supramolecular assemblies: colloidal onions, cubosomes, and hexosomes.

Amphiphilic molecules can self-assemble in solution into a variety of supramolecular assemblies, ranging from simple micelles, ribbons, and tubes to complex cubosomes with bicontinuous cubic nanostructures. It is well known that the self-assembly of chiral building blocks into one-dimensional (1D) twisted fibers, helical ribbons, and tubes enables chiral transfer from the molecular scale to super-assemblies. In this study, we investigate the chirality of three-dimensional (3D) supramolecular assemblies, such as colloidal onions, cubosomes, and hexosomes, formed from the same chiral heteroclusters. Unlike supramolecular 1D helical ribbons, these assemblies do not have chiral external shapes or chiral internal nanostructures, but they do exhibit circular dichroism, suggesting that they are chiral. Structural studies revealed that the ordered arrangement of the chiral units in curved superstructures is the origin of the supramolecular chirality of these 3D assemblies. Therefore, this study provides insights for enriching the diversity and complexity of supramolecular chiral assemblies.

Dynamical and Structural Properties of Comb Long-Chain Branched Polymer in Shear Flow.

Using hybrid multi-particle collision dynamics (MPCD) and a molecular dynamics (MD) method, we investigate the effect of arms and shear flow on dynamical and structural properties of the comb long-chain branched (LCB) polymer with dense arms. Firstly, we analyze dynamical properties of the LCB polymer by tracking the temporal changes on the end-to-end distance of both backbones and arms as well as the orientations of the backbone in the flow-gradient plane. Simultaneously, the rotation and tumbling behaviors with stable frequencies are observed. In other words, the LCB polymer undergoes a process of periodic stretched-folded-stretched state transition and rotation, whose period is obtained by fitting temporal changes on the orientation to a periodic function. In addition, the impact induced by random and fast motions of arms and the backbone will descend as the shear rate increases. By analyzing the period of rotation behavior of LCB polymers, we find that arms have a function in keeping the LCB polymer's motion stable. Meanwhile, we find that the rotation period of the LCB polymer is mainly determined by the conformational distribution and the non-shrinkable state of the structure along the velocity-gradient direction. Secondly, structural properties are numerically characterized by the average gyration tensor of the LCB polymer. The changes in gyration are in accordance with the LCB polymer rolling when varying the shear rate. By analyzing the alignment of the LCB polymer and comparing with its linear and star counterparts, we find that the LCB polymer with very long arms, like the corresponding linear chain, has a high speed to reach its configuration expansion limit in the flow direction. However, the comb polymer with shorter arms has stronger resistance on configuration expansion against the imposed flow field. Moreover, with increasing arm length, the comb polymer in shear flow follows change from linear-polymer-like to capsule-like behavior.

Efficient Broadband Near-Infrared Emission from Lead-Free Halide Double Perovskite Single Crystal.

Ultra-broadband near-infrared (NIR) luminescent materials are the most important component of NIR light-emitting devices (LED) and are crucial for their performance in sensing applications. A major challenge is to design novel NIR luminescent materials to replace the traditional Cr3+ -doped systems. We report an all-inorganic bismuth halide perovskite Cs2 AgBiCl6 single crystal that achieves efficient broadband NIR emission by introducing Na ions. Experiments and density functional theory (DFT) calculations show that the NIR emission originates from self-trapped excitons (STE) emission, which can be enhanced by weakening the strong coupling between electrons and phonons. The high photoluminescence quantum efficiency (PLQY) of 51 %, the extensive full width at half maximum (FWHM) of 270 nm and the stability provide advantages as a NIR luminescent material. The single-crystal-based NIR LED demonstrated its potential applications in NIR spectral detection as well as night vision.

Facile Microwave Synthesis of a Narrow-Band Green-Emitting Phosphor Cs3MnBr5 and the Effect of Anion Substitution on Its Luminescence Properties.

A bright blue light excitable and narrow-band green-emitting phosphor Cs3MnBr5 has been synthesized by a facile microwave radiation method within 2 min. The influence of the matrix on its steady-state and transient-state luminescence properties is investigated by partial substitution of Br- ions by Cl- ions. The incorporation of Cl- ions in Cs3Mn(Br1-xClx)5 resulted in almost no change in the emission maxima of Mn2+, which is attributed to the synergistic effect of reduced covalency and increased crystal field strength caused by the replacement of Br- ions by Cl- ions. Meanwhile, the emission of Mn2+ decreases with the increasing Cl- content, which is caused by different thermal quenching of Mn2+ emission in the mixed Cl-/Br- coordination. Moreover, the incorporation of Cl- in Cs3Mn(Br1-xClx)5 was found to have different effects on the lifetime of Mn2+ at different temperatures, that is, at room temperature, the lifetime of Mn2+ decreases with the increasing Cl- content, while at liquid nitrogen temperature, the lifetime of Mn2+ increases upon increasing the Cl- content. The former is due to the different thermal quenching for different coordinations of Mn2+ with Cl- and Br-, while the latter is due to the weaker spin-orbit coupling of the Mn2+ ion caused by the interaction with the lighter Cl- ions, which makes the spin selection rule stricter and leads to a longer lifetime of Mn2+ consequently.

A Trefoil Knot Polymer Chain Translocates through a Funnel-like Channel: A Multi-Particle Collision Dynamics Study.

With combining multi-particle collision dynamics (MPCD) for the solvent and molecular dynamics (MD) for the polymer chains, we have studied the conformation and untying behaviors of a trefoil knot polymer chain translocated through a confined funnel-like channel. For the trefoil knot chain, we found that the untying knot behavior mostly happens during the translocation process, and the translocation behavior of linear chains is also simulated as a comparison. Some characteristics of the trefoil knot chain during translocation process, such as average gyration radius and the average end-to-end distances are discussed, and we statistic the scale relations of the translocation time versus the chain length, and that of the chain rigidity. This study may help to understand translocation behaviors of the knotted linear polymer chain in the capillary flow field.

High antibacterial and barrier properties of natural rubber comprising of silver-loaded graphene oxide.

The antibacterial and barrier properties of natural rubber used as gloves are very important for the safety of medical staffs. In this research, the silver (Ag) particles were loaded on the surface of graphene oxide (GO) first modified by polydopamine (PDA). Then, the complex particles (Ag-PDA-GO) were introduced into the natural rubber (NR) latex, and the Ag-PDA-GO/NR film composites were obtained by the dipping method. Results showed that a fine dispersion of Ag-PDA-GO in NR film was obtained due to the isolation effect of Ag and PDA between GO sheets. Compared with those of pristine NR composite, when the GO content was only 0.2 phr, the tensile strength, tear strength and modulus at 100% and 300% strains of the composites increase by 66.7%, 128%, 37.7% and 30.7%, respectively, compared with the pure NR. The gas diffusion coefficient was reduced by 15.6% due to the strong interface interaction between GO and NR macromolecules. When the GO content was only 0.1 phr, the minimum inhibitory concentrations (MIC) of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 16 and 32 µg/mL, respectively. These results are of great significance for improving the barrier and antibacterial properties of medical rubber products.

Na+-functionalized carbon dots with aggregation-induced and enhanced cyan emission.

A new type of carbon dots that emit blue emission in aqueous state while cyan emission in solid state was synthesized by a simple hydrothermal method. The photoluminescence quantum yield of the carbon dots in aqueous state and solid state is 7.6% and 29.2%, respectively. The enhanced and red-shifted emission observed in solid state carbon dots is ascribed to surface state change caused by aggregation. The occurrence of surface state change in solid state carbon dots has been evidenced by concentration dependent steady-state photoluminecence spectra and time-resolved luminescence decay. Surface functionalization by Na+ is beneficial for carbon dots to resist luminescence quenching in solid state. A proof-of-concept study was performed to demonstrate the potential application of the obtained carbon dots as inks for anti-counterfeiting and printing high quality fluorescent images.

Preparation and Chemical Protective Clothing Application of PVDF Based Sodium Sulfonate Membrane.

Chemical protective clothing (CPC) is major equipment to protect human skin from hazardous chemical warfare agents (CWAs), especially nerve agents and blister agents. CPC performance is mainly dominated by the chemical protective material, which needs to meet various requirements, such as mechanical robustness, protective properties, physiological comfort, cost-effectiveness, and dimensional stability. In this study, polyvinylidene fluoride (PVDF) based sodium sulfonate membranes with different ion exchange capacities (IECs) are prepared simply from low-cost materials. Their mechanical properties, contact angles, permeations, and selectivities have been tested and compared with each other. Results show that membranes with IEC in the range of 1.5-2 mmol g-1 have high selectivities of water vapor permeation over CWA simulant vapor permeation and good mechanical properties. Therefore, PVDF-based sodium sulfonate membranes are potential materials for CPC applications.

Solid-State Carbon Dots with Efficient Cyan Emission towards White Light-Emitting Diodes.

Efficient cyan-emitting solid carbon dots (CDs) were synthesized via a one-pot hydrothermal method. The obtained solid CDs show a broad absorption from 270-460 nm with a maximum around 400 nm, and emit intense cyan light around 500 nm with an internal photoluminescence quantum efficiency of 34.1 % under 400 nm excitation. The emission maximum of the solid CDs remains unchanged under 320-400 nm excitations. Compared with dilute aqueous of CDs (2.5 mg mL-1 ), the emission of solid CDs shows an obvious red-shift of 50 nm. The red-shift is caused by resonant energy transfer due to larger spectral overlap and smaller interparticle distance, together with a new surface state caused by aggregation in solid CDs. A lamp with white LEDs was fabricated by dropping a mixture of solid CDs, CaAlSiN3 :Eu2+ and silicon resin on the top of a near-ultraviolet LED chip. Under an operating current of 20 mA, the as-fabricated white LED generates a high-quality, warm white light with a color rendering index of 86.1, a color temperature of 4340 K, and a luminescence efficiency of 31.3 lm W-1 .

Highly Green Emissive Nitrogen-Doped Carbon Dots with Excellent Thermal Stability for Bioimaging and Solid-State LED.

In this study, nitrogen-doped green emissive carbon dots (N-doped CDs) are synthesized via a convenient one-step solid state reaction method. The N-doped CDs show excitation-dependent fluorescence behavior with a maximum emission of 540 nm. Upon the optimum excitation at 400 nm, the quantum yield (QY) of the green emissive CDs is determined to be 13.4% and 50.3% in deionized water and ethanol, respectively. The higher quantum yield of N-doped CDs in ethanol could be caused by a strong hydrogen-bonding. In addition, the obtained N-doped CDs demonstrate excellent thermal stability, which is supported by the fact that the emission intensity nearly has no change after keeping the sample at 90 °C for 120 min. Moreover, the N-doped CDs exhibit green emission after entering into the HeLa cell membrane, indicating their potential to be used as bioimaging agent. Furthermore, the N-doped CDs are dispersed in PVA matrix for solid state film, where the solid-state quenching  is effectively avoided. A green LED is fabricated by packing the CDs-PVA composite on the top of a 395 nm n-UV-Chip, which provides a potentially healthy green light.

Synthesis of boronate-decorated polyethyleneimine-grafted porous layer open tubular capillaries for enrichment of polyphenols in fruit juices.

A combination between modification with porous layer and grafting of polyethyleneimine (PEI) on the inner face of capillary was for the first time developed for boronate affinity in-tube solid-phase microextraction (SPME) material to enhance the extraction capacity for cis-diol-containing polyphenols. The successful synthesis of boronate-decorated polyethyleneimine-grafted porous layer open tubular (BPPLOT) capillary was confirmed by scanning electron micrograph, Fourier transform-infrared spectra and absorption experiments. The porous layer, PEI and boronate affinity provided high specific surface area, more binding sites for boronate groups and specific selectivity of BPPLOT capillary, respectively. The maximum binding quantity of BPPLOT capillary greatly improved, and ranged from 143 to 170 µg m-1 for cis-diol-containing polyphenols (catechin, chlorogenic acid, caffeic acid and epicatechin). A green method based on boronate affinity in-tube SPME was developed for separation and enrichment polyphenols, and some parameters of in-tube SPME were optimized. After in-tube SPME, HPLC with UV detection was used for quantitative determination of polyphenols. Recoveries of standard spiked cis-diol-containing polyphenols from fruit juice were between 80.9% and 102%, with intra-day and inter-day coefficient of variation ranging from 4.8% to 7.3% and 5.0% to 8.6%, respectively. Conversely, recovery of non-cis-diol-containing ferulic acid was no greater than 3.0%. These results suggested that the BPPLOT capillary could effectively separate and enrich cis-diol-containing polyphenols from real samples.

Applicability Evaluation of Bright Green-Emitting Carbon Dots in the Solid State for White Light-Emitting Diodes.

Self-quenching-resistant and bright green-emitting carbon dots (CDs) in the solid state were synthesized via a facile hydrothermal method. Their structure, optical properties together with their thermal and photostabilities, as well as their applicability in white LEDs were investigated. The obtained CDs have nearly spherical shape with a size around 4-5 nm. The resulting powder CDs show excitation-independent emission behavior, and can be excited over a broad range from 300-450 nm. Under optimal excitation at 400 nm, the resultant powder CDs yield bright and broad green emission around 505 nm with full width at half maximum (FWHM) of about 110 nm and under 360 nm excitation with lifetime of 15.8 ns. A potential application of the green-emitting CDs was evaluated by constructing a white light-emitting diode lamp. The fabricated white LED lamp emitted bright, warm white light with excellent color rendering properties (a color rendering index of 86.9 and a correlated color temperature of 3863 K).

Ni-Al Bimetallic Catalyzed Enantioselective Cycloaddition of Cyclopropyl Carboxamide with Alkyne.

A Ni-Al bimetallic catalyzed enantioselective cycloaddition reaction of cyclopropyl carboxamides with alkynes has been developed. A series of cyclopentenyl carboxamides were obtained in up to 99% yield and 94% ee. The bifunctional-ligand-enabled bimetallic catalysis proved to be an efficient strategy for the C-C bond cleavage of unreactive cyclopropanes.

Near-infrared persistent luminescence of Yb3+ in perovskite phosphor.

Here we report the observation of near-infrared persistent luminescence (NIR PersL) of Yb3+ in perovskite CaTiO3. Sensitized by the Bi3+ codopants, it exhibits intense NIR PersL of Yb3+ at about 1000 nm. In addition, this phosphor can be excited by the near ultraviolet and even visible light, and the PersL signals can be recorded for more than 80 h. The PersL enhancement by Bi3+ is revealed to be due to the suitable Bi3+ induced deeper traps and the possible PersL quantum cutting. The results suggest that the NIR PersL of the CaTiO3:Yb3+, Bi3+ phosphor has potential applications for biomedical imaging in the second biological window.