POROSITY AND PORE SIZE DISTRIBUTION OF RECENT AND ANCIENT BURIED PHOEBE ZHENNAN WOOD DETERMINED BY MERCURY INTRUSION POROSIMETRY

The porosity and pore size distribution of recent and ancient buried Phoebe zhennan are studied in this paper by means of mercury intrusion porosimetry. The results show that the micropore and mesopore diameters of recent and buried wood are mainly distributed in range of 40.3 nm and 183.1 nm respectively, while the macropore in 45276.6 nm and 3503.9 nm separately. For both samples, the pores with diameters below 349.9 nm account for about 60% of the total intrusion volume, and contribute more than 98% of the surface area. The cumulative pore area of recent wood is slightly greater and the pore diameter ranges from 50.3 nm to 349.9 nm. While the cumulative pore area of buried wood is significantly larger than and the pore diameter ranges until 50.3 nm. These results can provide information for further investigations on the sorption behaviour and the liquid permeability of ancient buried wood.

Transcriptome Analysis to Elucidate the Enhanced Cold Resistance of Phoebe zhennan Pretreated with Exogenous Calcium

Phoebe zhennan is a high-quality timber tree species, and cold stress is one of the most remarkable abiotic factors limiting its growth and development. In this study, effects of exogenous CaCl2 on cold resistance of P. Zhennan were surveyed. CaCl2-pretreatment increased the levels of abscisic acid, peroxidase, catalase, proline, and soluble sugar, while decreased the levels of malondialdehyde and relative electrical conductivity. In addition, RNA-sequencing was used to investigate global transcriptome responses to cold stress. A total of 4245 differentially expressed genes were identified, including 477 up-regulated and 3768 down-regulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that these DEGs were associated to the plant-pathogen interaction pathway, in which calcium-dependent protein kinase (CDPK) play key role for improving the cold resistance of P. zhennan. Our results can be useful to understand the Ca2+-mediated cold resistance mechanism for improving cold stress tolerance in P. Zhennan seedlings. © 2021 Friends Science Publishers

Characterization of Ethyl Acetate and Trichloromethane Extracts from Phoebe zhennan Wood Residues and Application on the Preparation of UV Shielding Films

In this work, ethyl acetate (EA) and trichloromethane (TR) extracts were extracted from Phoebe zhennan wood residues and the extracts were then applied to the preparation of UV shielding films (UV-SF). The results revealed that substances including olefins, phenols and alcohols were found in both EA and TR extracts, accounting for about 45% of all the detected substances. The two extracts had similar thermal stability and both had strong UV shielding ability. When the relative percentage of the extract is 1 wt% in solution, the extract solution almost blocked 100% of the UV-B (280–315 nm), and UV-A (315–400 nm). Two kinds of UV-SF were successfully prepared by adding the two extracts into polylactic acid (PLA) matrix. The UV-SF with the addition of 24 wt% of the extractive blocked 100% of the UV-B (280–315 nm) and more than 80% of the UV-A (315–400 nm). Moreover, the UV shielding performance of the UV-SF was still stable even after strong UV irradiation. Though the addition of extracts could somewhat decrease the thermal stability of the film, its effect on the end-use of the film was ignorable. EA extracts had less effect on the tensile properties of the films than TR extracts as the content of the extract reached 18%. The results of this study could provide fundamental information on the potential utilization of the extracts from Phoebe zhennan wood residues on the preparation of biobased UV shielding materials.

The identification and characteristics of Phoebe zhennan buried wood

ABSTRACT The subject of this study is the structure and composition of buried Phoebe zhennan wood. Through comparative studies of the anatomy and composition with modern undegraded wood, the objective was to understand any changes that have taken place in the P. zhennan buried wood samples. The P. zhennan buried wood can be identified by wood structure characteristics and volatile components analysis. It is required that the microstructural features are identical to those of modern P. zhennan wood; simultaneously, the volatile components of the wood must contain six characteristic compounds with the same peak retention time. The P. zhennan buried wood sample which was used in the experiment was dated 8035–7945 BP (95. 4% probability). Further research showed that the cell wall of P. zhennan buried wood had been damaged, the hemicellulose was heavily degraded but there was no obvious degradation of crystalline cellulose. Moisture was present mainly as free water and large amounts of mineral elements such as Fe, and Ni were detected in the ash of P. zhennan buried wood. Both the buried and modern wood of P. zhennan were acidic.