Selective isomerization of 1-methylnaphthalene was carried out in a fixed-bed reactor over HBEA catalysts modified by acid and tetraethoxysilane treatments, respectively. Catalysts were characterized by X-ray diffraction, NH3 temperature-programmed desorption, N2 physisorption, inductively coupled plasma analysis, thermogravimetric analysis and Fourier transform infrared spectrometry after adsorption of pyridine. The results demonstrated that tetraethoxysilane treatment successfully passivated external active sites of the zeolite, but had little effect on the selectivity of isomerization reaction and catalytic stability. Dealumination of HBEA zeolite by treatment with oxalic and hydrochloric acids can lead to higher surface area and pore volume. Sufficiently strong Brönsted acidic sites were found to be responsible for the isomerization activity. Furthermore, a decrease in the number of Lewis acidic sites in acid-modified zeolites were advantageous to suppress the hydride transfer and subsequent side reactions that form coke, leading to higher 2-methylnaphthalene selectivity and longer catalytic life.

Bombyx Mori silk and polyvinyl acetate (PVAc) were combined in different ratios to form protein–synthetic polymer blend films. The effect of silk content on PVAc blends was investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). SEM images revealed that silk and PVAc in different ratios can form a homogeneous morphology. FTIR spectra suggested structural changes in the films such as the formation of beta-sheet crystals with the increase of PVAc content in the blends. A single glass transition temperature for each blend was found in DSC curves, indicating that a good miscibility existed in the blends. These protein–polymer blend films may be useful for a variety of applications in materials and biomedical fields.

Regenerated Thai silk fibroin films were successfully fabricated using a novel calcium chloride–formic acid solution system. Different concentrations of calcium chloride (1.0, 1.5, 2.0, 3.0, 4.0, and 6.0 mass% in formic acid) could be embedded into the silk structure, and their glass transition temperature (Tg), specific heat (Cp), and thermal stability were studied and compared by the methods including scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and step-scan DSC (SSDSC). The results showed that with the increase in the CaCl2 content during film fabrication, the ΔCp value of the final samples in the glass transition region gradually increased, while Tg and the thermal stability decreased, suggesting that a more non-crystalline structure formed in the sample produced with a high concentration of CaCl2. These findings offer a new strategy for the fabrication of biocompatible silk materials with different structures, and it can be used for different silk fibroins for various biomaterial applications in the future.

Poly(lactic acid) (PLA) is a green synthetic polymer which has many excellent properties useful for various applications. In this study, PLA scaffolds were fabricated at 2.0–6.0 MPa saturation pressures by using a solvent-free solid-state air gas foaming technique. Differential scanning calorimetry analysis was used to investigate the melting behavior and the mechanism of isothermal crystallization kinetics of these PLA scaffolds. Kinetics theories, such as Avrami analysis which was established for crystal growth studies of synthetic polymers, are for the first time utilized to investigate the air gas foamed scaffolds. Results showed that 6.0 MPa scaffolds had a 3D spherulitic crystal growth kinetics which is different from the raw PLA and 3.0 MPa foams. The experimental results also proved that two types of crystals: defective α′ and stable α coexisted in the PLA foams, and the contents of these two crystals were varied at different isothermal crystallization temperatures. Compared with the raw PLA, the crystallinities of PLA foams increased slightly after isothermal crystallization. However, the air gas molecules also hindered the crystallization rates of PLA foams. In addition, single crystals or perfect large crystals with α-form can be produced at a high isothermal crystallization temperature, such as 110 °C.

•Pressure-controllable green foaming technology is used.•The crystallinity and rigid amorphous fraction is calculated by using DSC and XRD.•We examine the changes of structure and property under different foaming pressures.•The mechanism of PLLA with different pore sizes at the molecular level is shown.Poly-l-lactide (PLLA) is one of the most promising biological materials used for tissue engineering scaffolds (TES) because of their excellent biodegradability and tenability. Here, microcellular PLLA foams were fabricated by pressure-controllable green foaming technology. Scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), wide angle X-ray diffraction measurement (WAXRD), thermogravimetric (TG) analysis, reflection-Fourier transform infrared (FTIR) analysis, enzymatic degradation study and MTT assay were used to analyze the scaffolds' morphologies, structures and crystallinities, mechanical and biodegradation properties, as well as their cytotoxicity. The results showed that PLLA foams with pore sizes from 8 to 103 μm diameters were produced when the saturation pressure decreased from 7.0 to 4.0 MPa. Through a combination of StepScan DSC (SSDSC) and WAXRD approaches, it was observed in PLLA foams that the crystallinity, highly-oriented metastable state and rigid amorphous phase increased with the increasing foaming pressure. It was also found that both the glass transition temperature and apparent enthalpy of PLLA significantly increased after the foaming process, which suggested that the changes of microcellular structure could provide PLLA scaffolds better thermal stability and elasticity. Moreover, MTT assessments suggested that the smaller pore size should benefit cell attachment and growth in the scaffold. The results of current work will give us better understanding of the mechanisms involved in structure and property changes of PLLA at the molecular level, which enables more possibilities for the design of PLLA scaffold to satisfy various requirements in biomedical and green chemical applications.

Thermogravimetric analysis and dynamic mechanical analysis were combined with scanning electron microscopy to analyze the thermo-mechanical properties and thermal stability of polylactic acid (PLA) foams fabricated using a solvent-free solid-state gas foaming method. The dependence of decomposition time and the lifetime on the PLA cell size was evaluated based on the thermal decomposition kinetic analyses. The results show that PLA specimens with larger cell sizes can be made at lower saturation gas pressures, which will ensure that the fabricated PLA foams have a shorter decomposition time, better flexibility, and are more satisfactory for medical requirements of tissue engineering scaffold (TES) material. The current work may help to optimize the PLA foaming parameters and precisely design PLA foams with different decomposition times according to specific TES requirements of different organ structures.

Hypocrellins, natural photosensitizers including hypocrellin A (HA) and hypocrellin B (HB), have been used as a traditional Chinese herbal medicine to cure various skin diseases. Hypocrellins have excellent antiviral activity, which can inhibit the growth of human immunodeficiency virus. They also exhibit significant light-induced antitumor property. In this article, thermal analysis technologies (e.g., differential scanning calorimetry and thermogravimetry) are employed to characterize whether the photosensitive hypocrellin A could be encapsulated with silica nanoparticle (SN) material or not, and evaluate the stability of inclusion complex. The results show that the inclusion complex exhibits improved performance in both stability and hydrophilicity than natural hypocrellin A. Fluorescence spectrophotometry studies have also been performed to verify the thermal analysis results. The results suggest that the thermal analysis technology could be used as an effective and rapid tool to characterize the encapsulation properties of the novel anticancer HA–SN complex.