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Lead telluride (PbTe) is an excellent thermoelectric material in the intermediate temperature zone and has been applied to deep space exploration, waste heat recovery and other fields. However, the low thermoelectric conversion efficiency of the n-type PbTe alloys limits its applications. Here, the thermoelectric performances have been enhanced in n-type PbTe alloys through trace bismuth (Bi) and iodine (I) co-doping. The Pb1-xBixTe1-xIx (x = 0.00%, 0.05%, 0.10%, 0.20% and 0.50%) alloys are synthesized in the single phase compounds by a stepwise synthesis method. The carrier concentration has reached an optimal concentration range within the order of 1019 cm-3. The highest absolute Seebeck coefficient of 244 μV/K is obtained for 0.05% doped alloy at 730 K. The highest absolute Seebeck coefficient leads to high power factor for 0.05% doped, especially in low- and middle-temperature range. The highest power factor ~ 25 μW/K2cm has been obtained at 329 K. Complex micro-scale grain boundaries and point defects strongly increase the phonon scattering and then lead to the lowest lattice thermal conductivity of 0.64 W/mK at 674 K for x = 0.50%, which is 26% lower than that of pristine PbTe. As a result, the highest figure of merit, zT ~ 0.9 has been determined in 0.20% doped samples at 725 K. Moreover, the highest average figure of merit, zTave ~ 0.7 has been achieved in 0.05% doped samples in the 323 - 723 K temperature range, which is about two or three times higher than reported for single Bi or I doped PbTe samples.

Porous hierarchical activated carbons (HACs) exhibit fascinating physical properties and are promising for supercapacitor applications. Facile and universal methods are required to produce high performance HACs on a large scale to boost their practical applications. An economical and template free method has been used to prepare HACs from lignocellulosic agricultural wastes with different contents of cellulose. These amorphous HACs exhibit high conductivity, a large specific surface area, and promising potentials for high performance supercapacitors. This study suggests the feasibility for facile and scalable conversion of inexpensive and earth-abundant agricultural wastes into high value-added carbon materials for energy storage applications.

Waterborne acrylic resin was prepared by emulsion polymerization (copolymerization of all acrylic monomers) and was modified by 2-(3,4-epoxy) ethyltriethoxysilane (KH567). The effects of KH567 on the properties of waterborne acrylic resin were investigated from the aspects of mechanical properties, thermal stability, and hydrophobicity. Fourier transform infrared spectroscopy (FTIR) analysis indicated that KH567 was grafted onto the molecular chain of acrylic resin. Differential scanning calorimetry (DSC) analysis showed that the curing temperature of the resin/KH567 (56.09 °C) was lower than that of pure resin (70.07 °C). Moreover, the contact angle of coating film increased to 90.4°. Additionally, the addition of KH567 could reinforce the spatial structure and increase the crosslinking density, and thus improved the tensile strength of the coating films properly while keeping other performances well. The work provides a simple way for the performance optimization of waterborne acrylic resin and represents a tendency for environmental friendly resin.

The effects of chlorinated polyethylene (CPE) and antimony trioxide (Sb2O3) on the flame retardancy and mechanical properties of the recycled polyvinyl chloride/acryl-butadiene-styrene (R–PVC/ABS) blends were investigated. The tensile strength of the blends with 40 wt% ABS, 35 wt% R–PVC and 25 wt% PVC was close to that of ABS. Both the limiting oxygen index and the vertical burning level were significantly improved, and the blends reached a flame retardant level. The notched impact strength was significantly improved with the addition of CPE. The SEM observed interpenetrating CPE network structure in the blends resulted in a significant ductile fracture of the blends. With the addition of Sb2O3, the limiting oxygen index and vertical burning grade of the blends were further improved; and the heat release rate, total heat of release and mass loss were significantly reduced. When the addition amount of CPE and Sb2O3 was 8 wt% and 6 wt% respectively, the tensile strength of the blends was 63.5 MPa, the notched impact strength was 9.2 kJ m−2, the limiting oxygen index was 31.3%, and the vertical burning grade reached V0 level. This study provides a way to reuse the polyvinyl chloride with enhanced properties.

Antifouling biocides releasing restricts the longevity of antifouling coatings. Compared with the anchoring state, the releasing behavior of agents is much faster on the voyage, while the biofouling process is tougher. In this work, a series of capsaicin-based pH-triggered polyethylene glycol/capsaicin@chitosan (PEG/CAP@CS), polyvinyl alcohol (PVA)/CAP@CS and alginate (ALG)/CAP@CS multilayer films are prepared with controlling antimicrobial properties in marine environments. There are 23.70, 23.35 and 22.06 ppb CAP releasing from (PVA/CAP@CS)20, (PEG/CAP@CS)20 and (ALG/CAP@CS)20 films after immersing in pH 4 solutions for 60 days, while only 13.07, 12.95 and 11.55 ppb CAP have been found in alkaline solutions after immersing for the same time, respectively. All these three types of films exhibit extraordinary pH responsive properties. They can control the CAP release at a low level in alkaline solutions, and make the CAP release fast in acid solutions. Moreover, the antibacterial properties against P.aeruginosa are outstanding about 95.84%, 95.0% and 96.91% for (PVA/CAP@CS)20, (PEG/CAP@CS)20 and (ALG/CAP@CS)20 films, respectively. The bacteriostasis of (ALG/CAP@CS)20 film keeps 92.73% after 60 days in alkaline solution, which means it is steadily controlled in the marine environment. Although with similar antibacterial properties to those of (PEG/CAP@CS)20 film, (PVA/CAP@CS)20 film displays the maximum decrease with about 92% in acid solution after 60 days. The ALG/CAP@CS film with the best-controlled release performance and long-term antibacterial properties provides novel guidance for developing new antifouling coatings application in the marine environment.

Isolation of earth abundant biopolymer, Lignin, from Dendrocalamus sinicus and their structural properties were investigated to achieve its large-scale practical applications in value-added products. Two lignin fractions (MWL, DSL) were isolated with successive treatments of dioxane and dimethylsulfoxide (DMSO) from dewaxed and ball milled bamboo (D. sinicus) sample. The two-step treatments yielded 52.1% lignin based on the total lignin content in the dewaxed bamboo sample. Spectroscopy analyses indicated that the isolated bamboo lignin was a typical grass lignin, consisting of p-hydroxyphenyl, guaiacyl, and syringyl units. The major interunit linkages presented in the obtained bamboo lignin were β-O-4' aryl ether linkages, together with lower amounts of β-β', β-5', and β-1' linkages. The tricin was detected to be linked to lignin polymer through the β-O-4' linkage in the bamboo. In addition, phenyl glycoside and benzyl ether lignin-carbohydrate complexes (LCC) linkages were clearly detected in bamboo (D. sinicus), whereas the γ-ester LCC linkages were ambiguous due to the overlapping NMR signals with other substructures. The detailed structural properties of the obtained lignin fraction together with the light-weight will benefit efficient utilization of natural polymers as a possibly large-scale bio-based precursor for making polymeric materials, biochemicals, functional carbon and biofuels, and multifunctional polymer nanocomposites.

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A convergent strategy was developed for the stereoselective synthesis of four unusual N-acylated monosaccharides (5-8), which are fragments of lipooligosaccharide IV (LOS-IV) from Mycobacterium marinum. A critical substrate-controlled asymmetric cyclization of an amino acid derived oxazolidine provided a key lactam intermediate 11, which was successfully converted to targets 5-7. The key step in the synthesis of 8 was a one-pot cascade oxidation-cyclization-oxidation reaction of a Boc-protected amino alcohol, prepared from 3-butynol, which led to the formation of lactam 15. The five-membered ring lactam intermediates in these synthetic routes were sensitive to elimination side reactions, but careful manipulation of the reaction sequence allowed for the stereoselective synthesis of the targets. This work represents the first synthesis of these unusual motifs, which have been shown to be essential to the bioactivity of LOS-IV.

Herein, we report the preparation of polyaniline (PANI) crystalline nanostructures and their dependent negative permittivity. By controlling the types of doped acids and the doping levels, PANI nanostructures with different crystallinity degrees are synthesized and composed of alternating metallic islands and amorphous regions confirmed by high resolution transmission electron microscopy (HRTEM). It's found that 0.15 mol L−1 of p-toluenesulfonic acid (PTSA) as doped acid is the optimal concentration to achieve a proper molecular weight (226,904 g mol−1) and higher degree of crystallinity (33.4%) from X-ray diffraction (XRD) for PANI. With further increasing the concentration of PTSA to 0.30 mol L−1, the degree of crystallinity (37%) of PANI has little change, but its molecular weight is quickly decreased to 35,102 g mol−1. As a consequence, the electrical conductivity of PANI increases from 1.1 × 10−3 S cm−1 for poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (p-AMPS) to 6.9 S cm−1 for PTSA and the PANI crystalline nanostructures doped with PTSA and hydrochloric acid possess a negative permittivity within the measured frequency range of 20 Hz to 2 MHz, whereas the permittivity for PANI doped with perchloric acid, phosphoric acid, camphorsulfonic acid, and p-AMPS switches from negative at low frequency to positive at high frequency. By calculation from AC conductivity, the charge carrier transport in these PANI systems follows the polaron hopping transport mechanism.

In this work, nitrogen and sulfur dual-doped carbon quantum dots (N,S-CDs) from naturally renewable biomaterial fungus fibers were prepared by a biosynthesis and hydrothermal method. The N,S-CDs displayed good water solubility, excellent stability, high quantum yield (QY = 28.11%) as well as remarkable features for fluorescence quenching-based detection and cellular imaging of cancer cells. It was worth mentioning that the heteroatoms doped carbon quantum dots made from the fungus fibers had a satisfactory QY and could be used as a selective, efficient, and sensitive fluorescent probe to determine tetracyclines by the synergistic effects of static quenching and internal filtration effect. The probe demonstrated a wide linear range and low detection limit. For tetracycline, the linear range was 0.5 μM to 47.6 μM, and the corresponding detection limit was 15.6 nM. Significantly, the test papers prepared by using N,S-CDs could detect tetracyclines in aquiculture wastewater rapidly. The produced N,S-CDs did not affect the cell viability and showed great promises for cellular imaging.

Multi-dimensional (MD) structures comprised of one-dimensional (1D) conductive building blocks are one of key components to develop micro-/nano-sized electronics, sensors, and energy storage devices. Some progresses have been made to fabricate polyaniline (PANI) dendritic or branch-like structures in the solid-state chemical process or by the use of organic acids or surfactant gel at low temperatures. Nevertheless, it remains a difficult challenge for obtaining PANI dendrites with solid form, regular morphology, and high aspect ratio branches. With sodium lauryl sulfonate (SLS) as the soft template, PANI dendrites were readily synthesized in an undisturbed and low acid environment. The effects of hydrochloric acid concentration and SLS dosage on the resulting PANI structures were carefully investigated. Particular mechanistic researches illuminate that the dendrites are prepared by the bottom-up hierarchical assembly behavior, in which 1D branches grow and aggregate into much more orderly architecture spontaneously. Electrochemical performances of the prepared PANI dendritic structures were carried out in a 1.0 M H2SO4 electrolyte. And the specific capacitance was 204 F g−1, when the current density was 0.50 A g−1. Employing PANI dendrites as an example, herein, the displayed method provides a discernment to a strategy of structure and performances for conducting polymers.

Graphene can form a liquid crystal phase due to its anisotropic flake characteristics, it shows great potential in the field of high dielectric composites. In this paper, the graphene oxide sheets are grafted onto copolymer to uniformly disperse and maintain the liquid crystal state in a non-polar solvent, then the modified graphene oxide liquid crystal is transferred to polydimethylsiloxane. Graphene/polydimethylsiloxane nanocomposites are obtained by high temperature reduction and curing reactions. When the filler content is 4 wt%, the permittivity increases by 800% compared to pure polydimethylsiloxane. Therefore, graphene liquid crystal can significantly improve the dielectric properties of the nanocomposites than ordinary graphene, which provides a new method for preparing high dielectric properties composites.

Aim The objective of this study is to evaluate the recovery of hearing function of auditory pathway after cochlear implantation by extracting the characterizations of electrically evoked auditory brainstem responses (EABR). The purpose of this study was to explore a reality and possible EABR test mode in clinical applications, rather than strict animal research.