Polyoxymethylene dimethyl ethers (DMM _n) are promising diesel additives. The synthesis of DMM _n from methylal (DMM) and paraformaldehyde over the NKC-9 acidic ion-exchange resin catalyst was investigated. Many unrecyclable by-products such as methyl formate, dimethyl ether and formic acid were produced in the reaction. To increase the selectivity of the desired products DMM_3‒6 and reduce the amount of unrecyclable by-products, the effects of reaction temperature, time, pressure and the molar ratio of the raw materials were evaluated through a series of single factor experiments. Experiments revealed that trace amount of water could suppress the formation of unrecyclable by-products, and the optimum initial water content (less than 2 wt%) was investigated. In addition, the synthetic process needs to go through the polyoxymethylene hemiformals intermediate stage, and then the DMM _n were obtained when polyoxymethylene hemiformals reacted with methanol. Ultimately, a possible mechanism is proposed to describe the formation of DMM _n from polyoxymethylene hemiformals in detail, in which it is revealed that the formation of carbocation intermediates is important in the reaction processes.

ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals (combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistance of anionic polyacrylamide (APAM). The resultant zeolites (AHN-ZSM-5) were characterized by XRD, ICP-OES, SEM, TEM, BET, NH₃-TPD, Py-IR, and TG analyses and evaluated in the methanol to gasoline (MTG) reaction. Characterization results show that the hierarchical ZSM-5 aggregates possessed two kinds of mesopores, namely inter- and intra-crystalline mesopores. The amount of APAM considerably influenced the mesoporosity and textural properties of AHN-ZSM-5 zeolites. With the addition of APAM in the synthesis, the AHN-ZSM-5 zeolites exhibited large mesopore volume, large external surface area, and appropriate acidity. When applied in the MTG reaction, AHN-ZSM-5 demonstrated a catalytic lifetime that was 1.6 times longer than that of conventional ZSM-5 synthesized in the absence of APAM.

Peanut-like hematite has been prepared by a new facile hydrothermal method and applied in the adsorption removal of As(V). The structural features of the as-prepared hematite were characterized systematically by X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, Fourier transform infrared spectroscopy, and transmission electron microscopy. Results showed that the morphologies of hematite could be tuned to spindle-like, oval-like, and cantaloupe-like shapes by adjusting the hydrothermal conditions. The peanut-like hematite formation followed a five-step route. At pH = 3, the adsorption amount of As(V) over peanut-like hematite reached 13.84 mg/g, and the adsorption kinetic process corresponded to the pseudo-second-order kinetic model. The peanut-like hematite also showed partial selectivity over As(V) in the hydrosphere. This method can be a reference for the preparation of other architectural metal oxide materials.

This study explained a procedure to synthesize 3D hexagram gold nanoparticles using a specific morphologically controlled gold precursor reduction. Acetaldehyde acted as the reducing agent along with polyvinyl pyrrolidone as the stabilizing agent with a limited reaction temperature range observed to be near to 25 °C. The resulting special gold nanoparticles were physically characterized and observed to possess an average planar size of 420 nm, an average central thickness of 200 nm, and an average edge thickness of 18 nm. Furthermore, a mechanism model was proposed to describe the oriented growth of gold nanoparticles employing published accounts of the mechanisms involved in the growth of gold hexagonal nanoplates. Moreover, the two major factors that controlled the morphology of synthesized gold nanoparticles were elaborated to provide reference for future fabrication methods of metal nanoparticles in both academia and industry.

The strain LWYZ003, which can restrain multiple pathogens, was screened from the sediment of the ocean and identified as Bacillus amyloliquefaciens. Large-scale fermentation and modern chromatographic separation technologies (macroporous resin column chromatography, silica gel column chromatography, thin-layer chromatography and high-performance liquid chromatography) were used to separate antimicrobial products from the fermentation broth of marine-derived Bacillus amyloliquefaciens LWYZ003. Bioactive-guided separation was used in the term of seeking antimicrobial products from the secondary metabolites of Bacillus amyloliquefaciens LWYZ003. As a result, two natural products cycloheximide (1) and trehalose (2) were obtained. Their structures were elucidated by Fourier transform infrared spectroscopy, high-resolution mass spectrometry, ¹H and ¹³C nuclear magnetic resonance analysis. In the cylinder plate method, compound 1 exhibited stronger antimicrobial activities than compound 2 against Micrococcus luteus, and also exhibited wider antimicrobial spectrum than compound 2. In conclusion, isolation of bioactive secondary metabolites from marine Bacillus sp. has enormous potentials in finding suitable antibiotics to inhibit multiple pathogens.

The imbibition ability of extinguishant is an important factor influencing the extinguishing effect for smoldering fire in pulverized coals. The coal particle size, bulk compactness, and aqueous solution properties significantly affect the imbibition ability of extinguishment. This work aims to reveal the influence of the properties of pulverized coals and aqueous solution on the imbibition ability of extinguishant for smoldering fire through experiments and capillary theories. The imbibition height and rate were adopted to evaluate the imbibition ability of extinguishment. The results showed that a relatively small bulk compactness and a fine coal particle size negatively influenced the extinguishing process dominantly because of its high surface energy and low wettability. An additive was used to adjust the properties of aqueous solution. The liquid with a larger surface tension, a smaller contact angle, and a lower viscosity induced a better imbibition ability of extinguishment.

In this study, liquid-phase aerobic oxidation of toluene catalyzed by Mn–Mo oxide was conducted in a 1.0 L batch reactor. The macroscopic kinetics of toluene consumption and benzaldehyde generation at 413–443 K were obtained from a combination of experimental observation and hypothetical models. The results clearly showed that both the oxidation rate of toluene and generation rate of the aromatic product were proportional to the concentration of the substrate, the partial pressure of oxygen and the surface area of the catalyst. The energy barrier of toluene oxidation to benzyl alcohol was the highest (≈ 81 kJ mol⁻¹), while that of benzyl alcohol oxidation to benzaldehyde was the lowest (≈ 57 kJ mol⁻¹). Moreover, the activation energy of further oxidation of benzaldehyde in an acetic acid solvent was only slightly lower (≈ 1.9 kJ mol⁻¹) than that of toluene oxidation. Significantly, the transformation of benzyl alcohol indeed contributed to the generation of benzaldehyde and this step conformed to a first-order parallel-consecutive model. Increased reaction temperature and residence time favored the transformation of benzyl alcohol to benzaldehyde. In addition, doping with molybdenum at Mn/Mo = 3/1 enhanced the catalytic performance of the heterogeneous catalyst and was attributed to the presence of a synergetic effect between different metal cations. Regarding the microscopic kinetics, the LH-OS-ND mechanism (Langmuir–Hinshelwood adsorption of reagents on the same type of active sites and non-dissociative adsorption of oxygen) was verified as responsible for the heterogeneous oxidation of toluene. Oxygen and benzaldehyde were weakly adsorbed (ΔH _ads,Oxy ≈ − 15 kJ mol⁻¹, ΔH _ads,Bald ≈ − 30 kJ mol⁻¹), but showed strong mobility (ΔS _ads,Oxy ≈ − 22 J mol⁻¹ K⁻¹), ΔS _ads,Bald ≈ − 39 J mol⁻¹ K⁻¹). The fundamental intrinsic rates were deduced based on the LH-OS-ND mechanism and showed great consistency with the macroscopic results.

This study described a regime map for dry neutralization agglomeration. Based on the map, the effects of selected key parameters, such as ingredient composition, operation temperature, agitation speed, and size of Na₂CO₃ particles, were investigated using a laboratory-scale mixer, and properties of the agglomeration product were analyzed, including particle size distribution, Hunter color, and flowability. Torque curves evolving during the process were correlated with the system flowability. Three distinguishable regimes were indicated, dry, wet, and transitional, and the agitation speed was found to have a different influence on the agglomeration process for the three regimes. Furthermore, the influence of temperature on reactive agglomeration significantly differed from that in agglomeration processes in which the binder was non-reactive.

The solubilities of fluorene in Exxsol D30, Exxsol D40, and crude dimethyl ethylbenzene (DME) from 299.25 to 356.85 K were investigated using the gas chromatography (GC) observation technique. Solubility curves were obtained based on the results and correlated with the modified Apelblat and λh equations to provide a valid model to predict the dissolution thermodynamic properties of fluorene at different temperatures, which is important in separating fluorene by crystallization.

A linear glucan was produced by Lactobacillus sake L-7 isolated from homemade sausage. Cultivation of the strain in Man–Rogosa–Sharpe (MRS) medium containing 50 g/L sucrose yielded 5.3 g/L of purified exopolysaccharide (EPS). The EPS was characterized by gas chromatography (GC), Fourier-transform infrared (FT-IR) spectroscopy, high-performance size-exclusion chromatography (HPSEC), nuclear magnetic resonance (NMR) spectroscopy, and scanning electron microscopy (SEM). The monosaccharide composition of the EPS was glucose, and its molecular weight was 1 × 10⁷ Da. The FT-IR and NMR spectra revealed that the L-7 EPS was a linear glucan with α-(1 → 6) glucosidic bonds. SEM images of the dried EPS revealed a hollow tubular structure. The water solubility index and water holding capacity of L-7 EPS were 96 and 272%, respectively. The results of hydrolysis indicated that L-7 EPS was not susceptible to hydrolysis by physiological barriers and can be used as a soluble dietary fiber with health benefits. All these characteristics suggest that L-7 EPS might have potential applications in the food, cosmetic, and pharmaceutical industries.

Acrylonitrile(AN)/1-vinyl-3-ethylimidazolium bromide (VIMB) copolymer was prepared via solution polymerization using dimethyl sulfoxide (DMSO) as a solvent and azodiisobutyronitrile as an initiator. The effects of comonomer VIMB on the polymerization, rheological properties of the polymer solution and thermal properties of the copolymer were investigated. The ionic liquid VIMB resulted in higher polymerization conversion ratio and higher average molecular weight when copolymerized with AN than itaconic acid (ITA). Rheological measurements indicated that the transition shear rate increased linearly with increasing temperature for P(AN/ITA)/DMSO solution, while an exponential growth with temperature was observed for P(AN/VIMB)/DMSO solution. The exothermic peaks of DSC curves in N₂ appeared at 276.67 and 257.34 °C for P(AN/VIMB) and P(AN/ITA), respectively. As a potential comonomer of AN for PAN carbon fibers, the VIMB resulted in about 7% higher char yield in N₂, and 23.7% less weight loss at 600 °C in air than ITA copolymer.

The complex relationships between indicators and water conditions cause fuzzy and gray uncertainties in evaluation of water quality. Compared to conventional single-factor evaluation methods, the combination evaluation method can consider these two uncertainties to produce more objective and reasonable evaluation results. In this paper, we propose a combination evaluation method with two main parts: (1) the use of fuzzy comprehensive evaluation and gray correlation analysis as submodels with which to consider the fuzzy and gray uncertainties and (2) the establishment of a combination model based on minimum bias squares. In addition, using this method, we evaluate the water quality of a ditch in a typical rice–wheat system of Yixing city in the Taihu Lake Basin during three rainfall events. The results show that the ditch water quality is not good and we found the chemical oxygen demand to be the key indicator that affects water quality most significantly. The proposed combination evaluation method is more accurate and practical than single-factor evaluation methods in that it considers the uncertainties of fuzziness and grayness.