Natural Polysaccharides as Multifunctional Components for One-Step 3D Printing Tough Hydrogels

Natural polysaccharides (NPS) are regarded as biomolecular and structural components for preparing high-performance tough hydrogels. But the one-step fabrication of NPS-containing hydrogels in seconds and the template-free design of complicated high-resolution structures are still significant challenges in this field. To meet these requirements, various NPS-containing tough hydrogels are fabricated and processed into 2D/3D structures via the combination of Ru(bpy)₃²⁺-mediated photochemistry and extrusion 3D printing technique. The whole fabrication process is one-step, completed in tens of seconds under visible light irradiation. It is found that the used NPS plays a key role in achieving the fabrication of high-performance structured tough hydrogels. The high reactivity of functional groups in the used NPS can shorten their gelation times. Long rigid chains of the used NPS, their hierarchical assemblies, and contrasting multinetworks benefit from the efficient dissipation of mechanical energy and enhancement of its operational stability. Strong supramolecular interactions enable hydrogel precursors to have high viscosities, therefore providing good controllability to design high-resolution and complicated tough hydrogel structures via extrusion 3D printing. It is anticipated that this straightforward fabrication strategy and findings will open new horizons for NPS-containing materials.     

A simple method for preparing graphene nano-sheets at low temperature

Graphene nano-sheets (GNs) with high quality were successfully synthesized in a Teflon-lined container through a low temperature expansion process. The influence factors of expansion temperature, expansion mode and reduction time on the morphology and structure of products have been systematically investigated, and an optimum experimental condition for the synthesis of GNs has been obtained. The results showed that the Teflon-lined container is an effective apparatus for preparing GNs at relative low temperature (<300 °C). The low temperature synthetic process is simple, inexpensive and easy to scale up in comparison with the traditional method which often consume more energy, use more complicated instruments, or more costly. The electrochemical properties of the as-synthesized products were investigated as anode materials for lithium ion batteries.     

A new polyanion with Dawson-like constitution: [H2SeW18O60]6 −

A new tungstoselenite, [H₂SeW₁₈O₆₀]^6 −, was isolated under acidic medium conditions (pH = 1.7)with the monoprotonated ethylamine as cation. It represents the first example of Se-containing polyoxometalate with unusual Dawson-like construction and has fully been characterized both in solid state and in solution. The high-resolution ESI-MS confirmed that the polyanion at least contains two protons and its proton number can be up to six in solution.     

The synthesis and catalytic activity to Li/SOCl2 battery of two new porphyrins

Two new porphyrins (3a, 3b) were synthesized and characterized by IR, UV–vis, ¹H NMR, MS and elementary analysis. The catalytic activity of the synthesized porphyrins to lithium/thionyl chloride (Li/SOCl₂) battery is evaluated by the relative energy of the battery whose electrolyte contains the porphyrins. The results indicate that the energy of Li/SOCl₂ battery catalyzed by porphyrins 3a and 3b is 101, 37% higher, respectively, than that of Li/SOCl₂ battery in the absence of the porphyrins. It can be used as a basis for the synthesis of more porphyrins with improved catalytic activity to Li/SOCl₂ battery in the future.     

Ultrasensitive Determination of Cadmium in Rice by Flow Injection Chemiluminescence Analysis

Based on the enhancing effect of Cd²⁺ on luminol–Co²⁺ chemiluminescence (CL) system, a sensitive method for determining picogram Cd²⁺ in rice by flow injection (FI)–CL was proposed. It was found that the CL intensity increments were proportional to the concentrations of Cd²⁺, giving a calibration graph linear over the Cd²⁺ concentrations ranging from 7.0 to 5,000.0 pmol L^?1, with a detection limit of 2.0 pmol L^?1 (3σ) and relative standard deviations (RSDs) of 3.2, 2.8, and 2.5 % for 30.0, 300.0, and 1,000.0 pmol L^?1 Cd²⁺ (n?=?5), respectively. At a flow rate of 2.0 mL min^?1, a complete determination of Cd²⁺ including sampling and washing could be accomplished within 36 s, giving a sample throughput of 100 h^?1. The contents of Cd²⁺ in rice were found to be 0.07–0.10 mg kg^?1. The proposed method was also applied to the determination of Cd²⁺ in spiked human serum samples with recoveries from 95.9 to 106.3 % and RSDs less than 4.0 %.     

Controllable preparation of SnO2 nanoplates and nanoparticles via hydrothermal oxidation of SnS2 nanoplates

A facile hydrothermal oxidation route has been proposed for the controllable preparation of SnO₂ nanoplates and nanoparticles, using the home-made SnS₂ nanoplates as a precursor. It was found that the temperature played an important role in the microstructures of the obtained products. While nanoplates of tetragonal phase SnO₂ were synthesized via hydrothermal treatment of the SnS₂ nanoplates in 15 vol.% H₂O₂ aqueous solution at 180 °C for 24 h, only nanoparticles of tetragonal phase SnO₂ could be obtained via hydrothermal treatment of the SnS₂ nanoplates in 15 vol.% H₂O₂ aqueous solution at 200 °C for 24 h. The as-prepared products were characterized by means of X-ray diffraction, field emission scanning electron microscope, and Raman spectra, and their possible formation mechanisms were also discussed.     

Bio-hydrogen production from cornstalk wastes by orthogonal design method

One-factor-at-a-time design and orthogonal design were used in the experimental design methods to optimize bio-hydrogen (bio-H₂) production from cornstalk wastes by anaerobic fermentation. Three series of experiments were designed to investigate the effects of substrate concentration, initial pH and orthogonal design on the bio-H₂ production by using the natural sludge as inoculant. Experimental results indicate that substrate concentration was the most significant condition for optimal hydrogen production. The optimum orthogonal design method was proposed to be at an enzymatic temperature of 50 °C, an enzymatic time of 72 h, an initial pH of 7.0 and a substrate concentration of 10 g/L. The proposed method facilitated the optimization of optimum design parameters, only with a few well-defined experimental sets. Under the proposed condition, the maximum cumulative H₂ yield was 141.29 ml g^?1-CS (cornstalk, or 164.48 ml g^?1-TS, total solid, TS = 0.859 W_{dried cornstalk}), with an average H₂ production rate of 12.31 ml g^?1-CS h^?1. The hydrogen content reached 57.85% and methane was not detected in the biogas.