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The 4.7 eV absorption band of colorless AlN crystal with the carbon concentration level of 107 cm−3 is investigated. An analysis of the absorption characteristics of the annealed AlN crystal indicates that the native defect is the origin of 4.7 eV absorption band and gives rise to an infrared absorption band at 2850 cm−1. The theory calculations predict two absorption bands at 4.65 eV and 0.35 eV of nitrogen vacancy, and the defect explains the increased and decreased intensity of infrared absorption band at 2850 cm−1 as well as a similar increased-decreased ultraviolet absorption band at 4.7 eV.

Three new tetramic acid derivatives (1–3) and a new polyketide (4) along with eight known compounds (5–12) were isolated from cultures of the deep-sea-derived fungus Penicillium sp. SCSIO06868. Four new structures were elucidated by analysis of one-dimensional/two-dimensional nuclear magnetic resonance (NMR) data and high-resolution electrospray ionization mass spectrometry. Their absolute configurations were established by X-ray crystallography analysis and comparison of the experimental and reported electronic circular dichroism (ECD) values or specific optical rotation. Compound 3 exhibited potent, selective inhibitory activities against Staphylococcus aureus and methicillin-resistant S. aureus with minimum inhibitory concentration values of both 2.5 μg/ml. Also, compound 3 showed weak antiviral activity against severe acute respiratory syndrome coronavirus 2 main protease, which was responsible for the coronavirus disease 2019 pandemic.

In this paper, the PetroOXY method has been mainly used to determine the oxidation stability of biodiesel stabilized with five synthetic antioxidants. The differences in the antioxidant activity of these phenolic compounds could be clearly distinguished with this method. Pyrogallol (PY) and propyl gallate (PG) prove more efficient in inhibiting biodiesel oxidative degradation than butylated hydroxyanisol (BHA) and butylated hydroxytoluene (BHT). BHT and BHA act more efficiently in the PetroOXY test than in the Rancimat method with regard to stabilization factor. Tert -butylhydroquinone (TBHQ) displays the weakest antioxidant activity in PetroOXY, inconsistent with the best stabilizing effects shown in the Rancimat method. The influence of reaction temperature on the induction period is very pronounced. From the plots of logarithm of induction period against temperature, the storage life of biodiesel at ambient temperature can be predicted with the extrapolation method, and the temperature sensitivity of these antioxidants can also be obtained. Changes in the mechanism of the oxidation process with the introduction of antioxidants may give variations in the temperature dependence.

In order to investigate the effects of the crosslinker on the separation performance of polar zwitterionic sulfoalkylbetaine-type monolithic columns, three crosslinkers, i.e. 1,4-bis(acryloyl)piperazine (PDA), ethylene dimethacrylate (EDMA) and N , N ′-methylenebisacrylamide (MBA), were copolymerized with the hydrophilic monomer N , N -dimethyl- N -acryloyloxyethyl- N -(3-sulfopropyl)ammonium betaine (SPDA). The chromatographic properties of the three hydrophilic sulfoalkylbetaine-type monolithic columns, including column efficiency, permeability, porosity and separation mechanism, were systematically compared using scanning electron microscopy or micro-HPLC. Good selectivity in micro-HPLC separations was achieved on all three monolithic columns. The results indicate that the polarity of sulfoalkylbetaine-type monolithic columns may be related to the polarity of the crosslinker, which further affects column selectivity and efficiency. A particularly high column efficiency (100,000 plates/m) was obtained on the novel poly(SPDA- co -PDA) monolithic column at a linear velocity of 1 mm/s using thiourea as test analyte. A higher resolution was also observed for nucleobases, nucleosides and hydrophilic organic acids on this novel poly(SPDA- co -PDA) monolithic column compared to the other two columns.

One-step pretreatment, anodization, is used to activate the polyacrylonitrile (PAN)-based carbon fibers instead of the routine two-step pretreatment, sensitization with SnCl2 and activation with PdCl2. The effect of the anodization pretreatment on the graphitization of PAN-based carbon fibers is investigated as a function of Ni-P catalyst. The PAN-based carbon fibers are anodized in H3PO4 electrolyte resulting in the formation of active sites, which thereby facilitates the following electroless Ni-P coating. Carbon fibers in the presence and absence of Ni-P coatings are heat treated and the structural changes are characterized by X-ray diffraction and Raman spectroscopy, both of which indicate that the graphitization of PAN-based carbon fibers are accelerated by both the anodization treatment and the catalysts Ni-P. Using the anodized carbon fibers, the routine two-step pretreatment, sensitization and activation, is not needed.

A novel carbon fiber pretreatment was proposed. Polyacrylonitrile (PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface, and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol. The as-treated carbon fibers were then graphitized at 2 400 °C for 2 h. The structural changes were characterized by X-ray diffractometry (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and high-resolution transmission electronic microscopy (HRTEM). The results show that much better graphitization can be achieved in the presence of Mo-B, with an interlayer spacing (d002) of 0.335 8 nm and a crystalline size (Lc) of 28 nm.

The effect of an externally applied magnetic field on the Fe–Ni catalyzed graphitization of phenolic resin was investigated. The Fe and Ni doped phenolic resin was first carbonized at 800 °C and then graphitized at different temperatures (800–1200 °C). Both the carbonization and graphitization were carried out in a magnetic field and the crystal structure was characterized by X-ray diffraction and transmission electron microscopy. The externally applied magnetic field was found to promote the graphitization and to improve the orientation of the hexagonal carbon layers. In the presence of Fe–Ni, a high degree of graphitization could be achieved by applying a magnetic field. This resulted in a d002 of 0.3355 nm and full-width at half maximum (FWHM) value of 0.103° after a 1200 °C heat treatment. In comparison, the absence of a magnetic field resulted in a d002 of 0.3358 nm and FWHM of 0.305°.

A C–N-doped TiO2 nanotube (NT)/carbon nanorod composite is fabricated by chemical vapor deposition (CVD). Carbon nanorods are grown from the TiO2 NTs, and partly graphitized, while TiO2 is in the mixture of anatase and rutile. The C–N doping shifts the absorption edge of TiO2 NTs to the visible light region; the formed carbon nanorods promote the charge carrier transfer from the TiO2 surface to the electrolyte. Under the simulated solar light irradiation, the C–N-doped TiO2 NTs show higher photocatalytic activity in the degradation of methyl orange (MO) than the undoped TiO2 NTs. Keywords: C–N-doped TiO2 nanotube, Carbon nanorod, Photocurrent, Photocatalyst

A novel carbon fiber pretreatment is proposed. PAN-based carbon fibers are first anodized in a H3PO4 electrolyte to achieve an active surface, and then coated with Ti–B catalyst by immersion of the carbon fibers in a uniformly dispersed H3BO3-doped TiO2 sol. The as-treated carbon fibers are then graphitized at 2400 °C for 2 h. The effects of the anodization and the Ti–B catalyst on the graphitization are investigated.