Xing’e Liu

Combustion characteristics of bamboo-biochars

Combustion characteristics of biomass are very important to directly utilize as an energy resource. Bamboo was carbonized using a XD-1200N muffle furnace in the nitrogen environment and its combustion characteristics were investigated. Results showed that bamboo-biochars had better combustion characteristics compared to bamboo materials, such as a lower content of moisture and volatiles, a higher energy density, HHV and EHC, a lower H/C and O/C ratios and a shorter TTI. Characteristic peak of bamboo-biochars shifted to higher temperature in thermal decomposition process, indicating a more steady-state burning and a higher combustion efficiency. Bamboo-biochars had a low content of S and N, which was helpful to decrease pollutant emissions. A higher content of K and Na was observed in the ash of bamboo-biochars, resulting in slagging, fouling, corrosion and agglomeration. The data from this research will be very helpful to efficiently design and operate its combustion systems.

Compression properties of vascular boundles and parenchyma of rattan (Plectocomia assamica Griff)

Abstract Rattan is a unique unidirectional vascular bundles-reinforced biocomposite with many nodes along its canes. Mechanical compression tests have been performed from rattan samples taken from different parts of the cross section. Compression strength increased with increasing amounts of vascular bundles (VBs) in the tissues was investigated. Samples including the outer ring with many VBs have the highest apparent Young’s modulus of 1.08 GPa and the highest compression strength of 17.6 MPa. However, samples consisting of parenchyma cells had an apparent Young’s modulus of 25 MPa, and the compression strength of 1.81 MPa. The compression properties of core samples improved with increasing amounts of VB. The apparent Young’s modulus and compression strength of a single VB were 730 MPa and 6.87 MPa, respectively, and were calculated according to the rule of mixture of composites.

Detection of complex vascular system in bamboo node by X-ray mu CT imaging technique

Abstract Bamboo is one of the world’s fastest growing plants. They reach a final height of 15–40 m during a period of 40–120 days. The full height is reached by intercalary growth of each node. However, it is very difficult to detect the complex vascular system in a bamboo node using traditional methods. X-ray computed microtomography (μCT) is a noninvasive novel approach to the three-dimensional (3D) visualization and quantification of biological structures. In the present article, μCT has been applied to provide insights into the internal structure of bamboo node, where three branches are connected. The picture obtained could hardly be obtained by any other means. The bamboo nodal characteristics of three transverse and axial sections are presented. The complex 3D network of vascular bundles has been directly obtained for the first time.

Structural Insight into Cell Wall Architecture of Micanthus sinensis cv. using Correlative Microscopy Approaches

Structural organization of the plant cell wall is a key parameter for understanding anisotropic plant growth and mechanical behavior. Four imaging platforms were used to investigate the cell wall architecture of Miscanthus sinensis cv. internode tissue. Using transmission electron microscopy with potassium permanganate, we found a great degree of inhomogeneity in the layering structure (4-9 layers) of the sclerenchymatic fiber (Sf). However, the xylem vessel showed a single layer. Atomic force microscopy images revealed that the cellulose microfibrils (Mfs) deposited in the primary wall of the protoxylem vessel (Pxv) were disordered, while the secondary wall was composed of Mfs oriented in parallel in the cross and longitudinal section. Furthermore, Raman spectroscopy images indicated no variation in the Mf orientation of Pxv and the Mfs in Pxv were oriented more perpendicular to the cell axis than that of Sfs. Based on the integrated results, we have proposed an architectural model of Pxv composed of two layers: an outermost primary wall composed of a meshwork of Mfs and inner secondary wall containing parallel Mfs. This proposed model will support future ultrastructural analysis of plant cell walls in heterogeneous tissues, an area of increasing scientific interest particularly for liquid biofuel processing.

Combustion characteristics of moso bamboo (Phyllostachys pubescens)

This study was carried out to investigate combustion characteristics of moso bamboo, including outer layer (OB), middle layer (MB) and inner layer (IB) and bamboo leaves (BL), respectively. The results showed that combustion characteristics of moso bamboo were similar to other biomass materials. There were two separate peaks in the combustion process; the first peak corresponding to combustion of volatile matters and the second peak corresponding to combustion of biochar. Compared to OB, MB and IB, BL had a worse fuel quality with higher H/C and O/C value, N and S content, ash content and lower combustion efficiency. Furthermore, BL had a higher slagging index and MB had a higher fouling index. These combustion characteristics of bamboo should be taken into consideration to efficiently design and operate the combustion systems when directly used for fuel production.

Evaluation of chemical treatments to tensile properties of cellulosic bamboo fibers

Acidified sodium chlorite (NaClO2) and sodium hydroxide (NaOH) solutions were successfully used to eliminate lignin and hemicellulose, respectively, from isolated bamboo fibers to investigate their microstructures, composition and micro-tensile properties in individual cellulose fibers. The results demonstrated that isolated fibers and chemically treated fibers clearly displayed different wrinkles, pores and microfibril aggregations on the cell wall surface. Field emission environmental scanning electron microscope images together with confocal scanning laser microscope measurements revealed that chemical treatments have a reduction effect on micro-tensile strength and modulus. Two methods of freeze-drying and air-drying produced varying interfaces and pores in microfibril aggregations and resulted in different tensile behavior. Notably, the reductions of Young’s modulus and tensile strength in freeze-drying (52.99 and 13.32%) fibers are larger than that (18.21 and 10.93%) in air-drying samples. These results suggest that most fractures occur in the weak interspaces or pores that are caused by the loss of matrix materials during chemical treatments.