Bamboo Nodes Research Articles

Bamboo nodes show nature's wisdom.

Bamboo nodes show nature's wisdom.

Vocal cord lesions in representative autoimmune diseases.

The aim of this study was to describe the clinical features of vocal cord lesions in patients with representative autoimmune diseases including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). A total of 31 SLE/RA patients (14 SLE and 17 RA) complicated with vocal cord lesions (SLE/RA-VC group) who had been admitted to Peking Union Medical College Hospital were retrieved from the electronic registration system. Ninety-three age and sex-matched SLE/RA patients (42 SLE and 51 RA) without vocal cord lesions (SLE/RA-nVC group) admitted during the same period were chosen randomly as controls. Medical files were reviewed and clinical data collected for comparisons. Vocal cord paralysis (n = 12, 38.7%) and vocal cord mass (n = 14, 45.2%) were the most common types of vocal cord lesions in this cohort. Unilateral lesions were more common than bilateral lesions(67.8%vs 32.3%) and the two sides were affected equally. Two cases of vocal cord bamboo node lesion were observed in SLE-VC group even as an initial manifestation and SLE-VC group had a slightly higher disease activity index (SLEDAI-2K) than their control counterparts (18.56 ± 8.23 vs 13.63 ± 5.89, p = 0.041). The RA-VC group had less pulmonary interstitial disease (29.4% vs 63%, p = 0.017) and lower CRP levels (p = 0.006) than their controls. As for the treatment, 71% of SLE/RA-VC patients had received glucocorticoids and immunosuppressants and 30% had undergone surgery. 45.2% of SLE/RA-VC patients got improvement at the time of discharge. The association of vocal cord lesions with disease activity can be observed in SLE patients but not in RA patients. Vocal cord lesions in SLE/RA patients should be considered as a part of the systemic involvement andshould be treated accordingly. Key Points • Vocal cord paralysis and vocal cord mass were the main types of vocal cord lesions in patients with SLE/RA. • Vocal cord lesions in SLE patients may associate with disease activity and vocal cord bamboo node lesions could be an initial manifestation. • Glucocorticoid and immunosuppressants could be effective for vocal cord lesions in SLE/RA patients.

Mode I fracture behavior of unidirectional bamboo laminate and its applications to the estimation of bamboo-steel-bamboo connections’ bearing capacities

Fracture caused by crack propagation is prevalent in bamboo laminate. Mode I fracture of bamboo laminate in which the fracture surface is composed of multilayer strips with fracture along the Tangential-Longitudinal (T-L) direction was studied. The load-crack opening mouth displacement (CMOD) curves of Mode I fracture, and the post-peak behavior of bamboo laminate were analyzed. The Mode I fracture toughness was calculated based on the modified beam theory. The effect of the bamboo node on fracture toughness was studied. The Mode I fracture toughness of bamboo laminate increases with the crack growth due to bamboo nodes. The toughening mechanism is the interlocking effect and fiber bridging on the uneven fracture surface. The mean value of the Mode I fracture toughness of unidirectional bamboo laminate panels along the y-x direction of the unidirectional bamboo laminate was suggested to be 225.7 J/m2 for the estimation of bamboo-steel-bamboo connections' bearing capacities. Based on the measured fracture properties of bamboo laminate and the fracture mechanics models, the brittle bearing capacities of the bamboo-steel-bamboo connections were discussed at the end of this research.

Mechanically robust bamboo node and its hierarchically fibrous structural design.

Although short bamboo nodes function in mechanical support and fluid exchange for bamboo survival, their structures are not fully understood compared to unidirectional fibrous internodes. Here, we identify the spatial heterostructure of the bamboo node via multiscale imaging strategies and investigate its mechanical properties by multimodal mechanical tests. We find three kinds of hierarchical fiber reinforcement schemes that originate from the bamboo node, including spatially tightened interlocking, triaxial interconnected scaffolding and isotropic intertwining. These reinforcement schemes, built on porous vascular bundles, microfibers and more-refined twist-aligned nanofibers, govern the structural stability of the bamboo via hierarchical toughening. In addition, the spatial liquid transport associated with these multiscale fibers within the bamboo node is experimentally verified, which gives perceptible evidence for life-indispensable multidirectional fluid exchange. The functional integration of mechanical reinforcement and liquid transport reflects the fact that the bamboo node has opted for elaborate structural optimization rather than ingredient richness. This study will advance our understanding of biological materials and provide insight into the design of fiber-reinforced structures and biomass utilization.

Evaluation of the in-plane shear properties of bamboo strips (Phyllostachys edulis) with the Iosipescu test and theoretical models based on composite mechanics

Abstract Engineered bamboo products have been increasingly used in construction. However, there are few studies on its shear performance. Thus, the shear properties of bamboo lamina strips were investigated by the Iosipescu shear test. This study aimed to obtain the shear stress-strain curves and the lamina’s corresponding strength and modulus values, which can be used to design and model bamboo structural components. With this goal, 120 specimens were tested, considering the effect of loading directions on bamboo fiber, the existence of bamboo nodes, standard thickness, and fiber volume fraction. The characteristic shear strength values were also estimated based on the test data. Results show that the bamboo nodes and standard thickness have a negligible effect on the shear modulus and strength values. In contrast, the shear properties were determined by the loading directions and fiber volume fraction. The specimens’ measured shear strength and modulus loaded parallel/perpendicular to the bamboo fiber direction were about 10 MPa/15 MPa and 550 MPa/1000 MPa. The fiber and matrix-dominate failure modes were noticed for the specimens, and the unidirectional bio-fiber reinforced composite theoretical model could be used to predict the modulus values of fiber-dominate samples based on the measured volume fraction of the fiber.

Interlaminar fracture property of Moso bamboo strips influenced by fiber distributions in bamboo internode and node

Bamboo is widely used as sustainable bio-composite material in the construction of houses, pavilions, furniture, and bridges, etc. As a unidirectional fibrous composite, it is usually damaged due to the interlaminar crack, which is directly related to the corresponding microstructure. In this study, the different fracture performances between bamboo internode and bamboo node are researched, as well as the fiber distributions in these zones. For the internode specimens, the results show that specimens with higher fiber contents tend to exhibit higher fracture energy than the case of lower fiber contents, so the fracture energy presents the functional gradient characteristics with fiber content. It is mainly because that more longitudinal vascular bundles make the fracture crack more tortuous and ultimately need more fracture energy. Furthermore, the node specimens have much-strengthened fracture performance than internode specimens with the same fiber contents, due to the radial fibers distributing in the bamboo node. The microscopic observation results indicate that the existence of radial vascular bundles causes the fracture process to include multiple damage modes such as interface delamination, vascular bundle pull-out, and crack deflection and finally play the effect of resisting crack propagation.

Fluoride-bridged dinuclear dysprosium complex showing single-molecule magnetic behavior: supramolecular approach to isolate magnetic molecules.

Using Na-encapsulated benzo[18]crown-6 (Na)(B18C6) as a counter cation, we successfully magnetically isolated a fluoride-bridging Dy dinuclear complex {[(PW11O39)Dy(H2O)2]2F} (Dy2POM) with lacunary Keggin ligands. (Na)(B18C6) formed two types of tetramers through C–H⋯O, π⋯π and C–H⋯π interactions, and each tetramer aligned in one dimension along the c-axis to form two types of channels. One channel was partially penetrated by a supramolecular cation from the ±a-axis direction, dividing the channel in the form of a “bamboo node”. Dy2POM was spatially divided by this “bamboo node,” which magnetically isolated one portion from the other. The temperature dependence of the magnetic susceptibility indicated a weak ferromagnetic interaction between the Dy ions bridged by fluoride. Dy2POM exhibited the magnetic relaxation characteristics of a single-molecule magnet, including the dependence of AC magnetic susceptibility on temperature and frequency. Magnetic relaxation can be described by the combination of thermally active Orbach and temperature-independent quantum tunneling processes. The application of a static magnetic field effectively suppressed the relaxation due to quantum tunneling.

3D Visualization of Bamboo Node’s Vascular Bundle

The vascular bundle is an important structural unit that determines the growth and properties of bamboo. A high-resolution X-ray microtomography (μCT) was used to observe and reconstruct a three-dimensional (3D) morphometry model of the vascular bundle of the Qiongzhuea tumidinoda node due to its advantages of quick, nondestructive, and accurate testing of plant internal structure. The results showed that the morphology of vascular bundles varied significantly in the axial direction. In the cross-section, the number of axial vascular bundles reached a maximum at the lower end of the sheath scar, and the minimum of it was at the middle of the diaphragm. The frequency of axial vascular bundles decreased from the lower end of the node to the nodal ridge, and subsequently increased until the upper end of the bamboo node. The proportion of parenchyma, fibers, and conducting tissue was 65.7%, 30.5%, and 3.8%, respectively. The conducting tissues were intertwined to form a complex 3D network structure, with a connectivity of 94.77%. The conducting tissue with the largest volume accounted for 60.26% of the total volume of the conducting tissue. The 3D-distribution pattern of the conducting tissue of the node and that of the fibers were similar, but their thickness changed in the opposite pattern. This study revealed the 3D morphometry of the conducting tissue and fibers of the bamboo node, the reconstruction of the skeleton made the morphology more intuitive. Quantitative indicators such as the 3D volume, proportion, and connectivity of each type of tissue was obtained, the bamboo node was enlarged mainly caused by the particularly developed fibers. This work laid the foundation for a better understanding of the mechanical properties and water transportation of bamboo and revealed the mystery of bamboo node shedding of Q. tumidinoda.

Experimental investigation of full-culm bamboo tubes strengthened by filled concrete and bamboo sheets under axial compression

To solve the problem of low compressive bearing capacity for the full-culm bamboos caused by their radial gradient variation and limited wall thickness, a new method, in which the concrete was filled inside the cavities of bamboo tubes and the bamboo sheets were wound onto the bamboo tubes with epoxy resin adhesive, was proposed in this paper to improve the behavior of full-culm bamboo structural members. The failure modes, ultimate bearing capacity of full-culm bamboo tubes with or without nodes, concrete-filled full-culm bamboo columns (CBs) and bamboo sheet-strengthened concrete-filled full-culm bamboo tubes (BSCBs) were investigated. Finally, the ultimate bearing capacity prediction method for CBs and BSCBs was studied based on the existing typical FRP-confined concrete columns. The results showed that the existence of bamboo nodes in the full-culm bamboo tubes may result in a decrease in the bearing capacity. In particular, the ultimate stress of specimens with relatively larger diameters and without nodes can be increased by a maximum of 18.2% compared to tubes with bamboo nodes. The ultimate bearing capacity of the full-culm bamboo tubes can obviously be increased using the scheme of filling concrete internally and strengthening by bamboo sheets externally. The average ultimate bearing capacity of CBs can be increased by a maximum of 65.3% compared with the corresponding full-culm bamboo tubes, and the average ultimate bearing capacity of BSCBs is at most 2.51 times higher than that of corresponding CBs. Although the bamboo tube and concrete cannot simultaneously reach the ultimate bearing capacity due to a certain difference in terms of their mechanical properties, such as the peak strain and elastic modulus, the ultimate bearing capacity of CBs and BSCBs can be predicted accurately using some existing typical strengthening models in terms of FRP-confined concrete columns.

Effect of Bamboo Nodes on the Mechanical Properties of P. edulis (Phyllostachys edulis) Bamboo

In the context of global sustainable development, the use of natural and renewable bamboo as a building material is of great significance for building engineering. As an important part of bamboo, there is still a lack of systematic research on the effect of bamboo nodes on the mechanical properties of bamboo. In this paper, compression parallel to the grain of the bamboo, bending, tensile parallel to the grain, shear parallel to the grain, compression perpendicular to the grain and tensile perpendicular to the grain tests of an entire bamboo culm of P. edulis bamboo were carried out, and the effects of bamboo nodes on moisture content, bearing capacity and mechanical properties were analyzed. The relationship between the mechanical properties and standardized parameters of the node and internode specimens was established. A conversion method of mechanical properties of the same test type was proposed, and a conversion method among different mechanical properties was proposed. The bamboo was graded by tensile strength parallel to the grain. The results show that bamboo nodes have an obvious effect on the moisture content. Bamboo nodes have different effects on the bearing capacity and mechanical properties of different types of specimens. The mechanical properties of P. edulis bamboo can be predicted by the relationship between the mechanical properties and the standardized parameters and the mechanical property conversion method. The strength classification of P. edulis bamboo can be predicted by standardized parameters.

Characterization of radial bamboo slivers from different height positions and their effect on the mechanical properties of bamboo-wood composite container flooring

ABSTRACT Bamboo-wood composite container flooring (BWCCF), as a low-cost, sustainable, and eco-friendly product, plays an increasing role in the container flooring industry. In this paper, the structural characteristics of radial bamboo slivers (RBS) from different locations of bamboo culms were studied. Furthermore, the mechanical performance and failure mechanisms of 17-layer BWCCF, made of radial bamboo sliver curtains from the top (top-CF), middle (middle-CF), and bottom (bottom-CF) sections of bamboo culms, were evaluated. It was found that the geometry of the top-RBS was more irregular than the middle and bottom-RBS resulting in more structural defects of the top-CF and higher standard deviation of its mechanical properties. Except for the MOE, the top-CF is 7.0% lower than the middle-CF, there is a small difference between the strengths of the top and middle-CF. Since lower fiber volume fraction and larger bamboo node numbers of bottom-RBS, the density, concentrated load, modulus of elasticity (MOE), modulus of rupture (MOR), and shear strength parallel to grain (fs||) of the middle-CF are 6.3%, 3.3%, 7.3%, 14.7%, and 3.1%, respectively higher than those of bottom-CF. The failure modes of concentrated load for the top, middle, and bottom-CF were different mainly because the number of RBS included in corresponding RBSC was different.

FLEXURAL LOAD AND DEFLECTION BEHAVIOR OF STRUCTURAL BAMBOO FILLED WITH CEMENT MORTAR

Bamboo has been significantly and rapidly used to build temporal and permanent structures since time immemorial. However, this renewable natural material has a low bearing capacity, limiting its application to structures under light loads. Therefore, this research was carried out to determine an innovative scheme capable of enhancing bamboo's load-bearing by filling the cavity with cement mortar. Furthermore, a study was carried out to experiment flexural load carrying capacity and the deflection of mortar-filled structural bamboo by considering the diameter and node parameters. A total of 12 specimens were examined using a four-point bending protocol. The result showed the ultimate flexural load carrying capacity of mortar-filled bamboo specimens are higher than those of the conventional bamboo specimens. Specifically, mortar filled bamboo specimen with a diameter of 70 mm was significantly better, 41.10 and 47.06%, as compared than the conventional bamboo in terms of its flexural load carrying capacity for specimen without and with nodes, respectively. Increases in flexural load carrying capacity were also observed for the mortar-filled bamboo specimens having 80 and 90 mm diameter and these observed increases were recorded as 104.55 and 112.00%, and 48.72 and 60.74%, respectively for specimen without and with nodes. Furthermore, the deflection of mortar-filled bamboo elements are substantially greater than those of conventional. Finally, the advantages of the bamboo diameter and bamboo nodes on the flexural load carrying capacity indicated that these essential findings need to be carefully considered in designing structural elements for both mortar-filled and conventional bamboos.

Asymmetric flexural process and fracture behaviors of natural bamboo node with gradient discontinuous fibers

Natural bamboo node samples bended from two opposite radial directions (Type I and Type II) displayed asymmetric flexural fracture process and behaviors. The real-time flexural process and fracture behaviors were observed and analyzed with the aid of optical video microscopy and acoustic emission (AE). Results indicated there are three kind of fracture behaviors within bamboo node during the deformation and fracture process, which are parenchyma cells failure, fiber dissociation and fiber breakage. They showed different sequences due to the gradient discontinuous fibers within bamboo node. The toughening mechanisms within bamboo node are concluded as cellular-fibrous effect, crack deflection, fiber bridging/pull-out and the induced avalanche delay.

Bamboo node effect on the tensile properties of side press-laminated bamboo lumber

At present, most of the existing studies on bamboo nodes focus on the raw bamboo. There is still a lack of researches on the nodes in side press-laminated bamboo lumber (LBL). However, after processing, bamboo nodes in the laminated bamboo lumber are different from the raw bamboo nodes in terms of performance. Therefore, this paper carried out tests to analyze the influence of bamboo node on the tensile properties parallel to grain of side press-laminated bamboo lumber. A total of 180 specimens were divided into six groups, and the number and position of the bamboo nodes at the specimen in each group were different. The effects of these factors on the strength, elastic modulus, and Poisson’s ratio of the side press-laminated bamboo lumber under tension parallel to grain were obtained. The tensile failure of side press-laminated bamboo lumber was a brittle fracture, and the typical failure mode can be classified into three types. The mean value for tensile strength was 127.18 MPa when there was no bamboo node, while the mean value was 89.99–107.37 MPa when there were one to three bamboo nodes. The number of bamboo nodes would significantly affect the tensile properties parallel to grain of side press-laminated bamboo lumber, whereas the position of bamboo nodes has an insubstantial impact. Comparisons with other research results were also carried out. A series of formulas were proposed based on the test results to reflect how the node influenced the mechanical properties of side press LBL under tensile conditions.

Nodes Effect on the Bending Performance of Laminated Bamboo Lumber Unit

This research studied the ultimate bearing capacity of laminated bamboo lumber (LBL) unit and thereby calculated the maximum bending moment. The load-displacement chart for all specimens was obtained. Then the flexural capacity of members with and without bamboo nodes in the middle section was coMPared. The bending experiment phenomenon of LBL unit was concluded. Different failure modes of bending components were analysed and concluded. Finally, the bending behaviour of LBL units is coMPared with other bamboo and timber products. It is shown that the average ultimate load of BS members is 866.1 N, the average flexural strength is 101 MPa, the average modulus of elasticity is 8.3 GPa, and the average maximum displacement is 17.02 mm. The average ultimate load of BNS members is 1008.1 N, the average flexural strength is 118.02 MPa, the average modulus of elasticity is 9.9 GPa, and the average maximum displacement is 18.26 mm. Laminated bamboo lumber (LBL) unit without bamboo nodes (BNS) has relatively higher flexural strength coMPared with LBL unit with bamboo nodes (BS). The presence of bamboo nodes reduces the strength of the entire structure. Three failure modes were concluded for BS members, and two failure modes were observed for BNS members during the experimental process. According to a coMParison between the LBL unit and other products, the flexural strength and bending modulus of elasticity of the LBL unit are similar as bamboo scrimber and raw bamboo components, which is much higher than timber components.

Visualizing Complex Anatomical Structure in Bamboo Nodes Based on X-ray Microtomography

Visualizing Complex Anatomical Structure in Bamboo Nodes Based on X-ray Microtomography

Prediction of Mechanical Properties of Structural Bamboo and Its Relationship with Growth Parameters

Bamboo is a renewable natural building material with good mechanical properties. However, due to the heterogeneity and anisotropy of bamboo stalk, a large amount of material performance testing costs are required in engineering applications. In this work, longitudinal compression, bending, longitudinal shear, longitudinal tensile, transverse compression and transverse tensile tests of bamboo materials are conducted, considering the influence of the bamboo nodes. The mechanical properties of the whole bamboo stalk with the wall thickness and outer circumference are explored. Through univariate and multiple regression analysis, the relationship between mechanical properties and wall thickness and perimeter is fitted, and the conversion parameters between different mechanical properties are derived. The research results show that the transverse compressive strength of nodal specimen, and transverse tensile strength of nodal and inter-node specimens increase with the increase of wall thickness and outer circumference, but other mechanical properties decrease with the increase of wall thickness and outer circumference. The prediction formula and conversion parameters of bamboo mechanical properties proposed in this research have high applicability and accuracy. Moreover, this research can provide references for the evaluation of bamboo performance and saving test costs.

Effects of node with discontinuous hierarchical fibers on the tensile fracture behaviors of natural bamboo

Bamboo is widely planted in the world and many species of bamboo are intensively used as sustainable bio-composite materials in the construction of houses, pavilions, furniture and bridges, etc. The bamboo nodes play an important role on natural bamboo's strength. This paper is focused on the structure-property-fracture relations of the natural Moso bamboo with node. The inner structures are characterized by optical and scanning electron microscopy (SEM), which indicated that bamboo node has coarser fiber bundles, higher volumes of fibers and 3D woven hierarchical fibrous structures. Though the fibers on the out and inner skins of node are discontinuous, it has higher strength than internodes samples. There are three kinds of fracture behaviors within bamboo node during the tensile fracture process as detected by acoustic emission (AE), which are matrix (parenchyma cells) failure, fiber dissociation and fiber breakage. The AE results indicated bamboo node has much lower volumes of fracture behaviors, higher proportions of fiber dissociation and matrix failure due to its hierarchical fibrous woven structure. The strengthening effects within bamboo node are concluded as coarse fiber bundles, high volumes of fibers, fiber pull-out and crack deflections.

Multifunctional solar bamboo straw: Multiscale 3D membrane for self-sustained solar-thermal water desalination and purification and thermoelectric waste heat recovery and storage

Solar desalination and purification based on interfacial evaporation have great potential to alleviate global water scarcity. However, real-world interfacial evaporation suffers from several issues in clean water collection and solar-to-clean-water energy efficiency. Here, a new concept of multifunctional natural membrane interfacial evaporation (MNMIE) is demonstrated, achieving the whole cycle of energy conversion from solar energy harvesting to waste heat recovery and storage while effectively desalinating and purifying water. The 3D, multiscale membrane derived from sustainable bamboo presents a mean pore size of 150 nm and a porosity of 63.8%, comparable to the commercial membranes. The as-generated vapor from a self-sustained evaporation process is guided to permeate through the porous bamboo node into the bamboo chamber facing unfocused incident light (1 sun) and then condenses, resulting in a high water collection ratio of 81.0% and solar-to-clean water efficiency of 67.4%. Moreover, the waste heat from desalination is recovered through direct thermoelectric energy conversion and storage under unfocused solar light. The fully integrated cycle of energy conversion, storage, and utilization for clean water and electricity generation enabled by the multifunctional natural membrane is scalable, economic and represents a highly promising solution for sustainable energy cycles enabled by nanotechnology-empowered natural resources.

Surface‐Carbonized Bamboos with Multilevel Functional Biostructures Deliver High Photothermal Water Evaporation Performance

AbstractInterfacial solar steam generation (ISSG) has attracted global attention as an important approach for water purification and desalination. The related photothermal materials based on 3D biostructures are promising due to their abundance and easy accessibility. Here, it is shown that surface‐carbonized bamboo (SC‐bamboo) as a photothermal material exhibits outstanding ISSG performance due to its multilevel functional biostructures. On a microscopic scale, the bamboo's air‐filled parenchyma cells promote thermal insulation while its vascular bundles ensure rapid water transport. On a macroscopic scale, a unique concave structure at the bamboo nodes concentrates water and heat in a confined region and the air‐filled hollow chambers in bamboo internodes also ensure thermal insulation. These multilevel functional structures of SC‐bamboo result in a solar‐thermal conversion efficiency up to 93.63% ± 1.57% under 1 kW m−2 irradiation, surpassing most biomass‐derived materials ever reported. Considering bamboo's low cost and convenience, this work sheds light on the design and fabrication of readily accessible, multilevel functional structure for efficient photothermal‐conversion devices.