Unveiling the mechanisms of Moso bamboo's motor function and internal growth stress.

Bamboo, a renewable resource with rapid growth and an impressive height-to-diameter ratio, faces mechanical instability due to its slender structure. Despite this, bamboo maintains its posture without breaking in its battle against environmental and gravitational forces. But what drives this motor function in bamboo? This study subjected Moso bamboo (Phyllostachys edulis) to gravitational stimulation, compelling it to grow at a 45° angle instead of upright. Remarkably, the artificially inclined bamboo exhibited astonishing shape control and adjustment capabilities. The growth strain was detected at both macroscopic and microscopic levels, providing evidence for the presence of internal stress, namely growth stress. The high longitudinal tensile stress on the upper side, along with a significant asymmetry in stress distribution in tilted bamboo, plays a pivotal role in maintaining its mechanical stability. Drawing upon experimental findings, it can be deduced that the growth stress primarily originates from the broad layers of fiber cells. Bamboo could potentially regulate the magnitude of growth stress by modifying the number of fiber cell layers during its maturation process. Additionally, the microfibril angle and lignin disposition may decisively influence the generation of growth stress.

[Trans-Douglas Retzius' space-sparing robot-assisted simple prostatectomy for large-volume benign prostate hyperplasia].

OBJECTIVE: To report the safety and efficacy of trans-Douglas Retzius' space-sparing robot-assisted simple prostatectomy (RSS-RASP) in the treatment of large-volume BPH. METHODS: This retrospective study included 24 cases of large-volume (>80 ml) BPH treated by trans-Douglas RSS-RASP from August 2019 to June 2021. The patients ranged in age from 55 to 80 (mean 68.5) years, with an average body mass index of 25.1 (20.5－34.9) kg/m2 , median prostate volume of 132.4 (85.6－235.7) ml, and preoperative tPSA of 10.8 (0.5－37.9) ng/ml, IPSS of 25 (3－35) and quality of life (QOL) score of 5 (3－8). Before surgery, 12 of the patients received catheterization for urinary retention, 1 underwent cystostomy, 2 were complicated with hydronephrosis, 1 had stones and diverticulum in the bladder, and 14 were excluded from the cases of PCa by prostatic biopsy. The operation time, intraoperative blood loss, hemoglobin level on the first day after surgery, blood transfusion, and intra- and postoperative complications were recorded. The patients were followed up for 3 to 21 months postoperatively. Comparisons were made before and after operation in the IPSS, maximum urinary flow rate (Qmax), postvoid residual volume (PVR), QOL score, IIEF score and Male Sexual Health Questionnaire (MSHQ) score. RESULTS: Trans-Douglas RSS-RASP was successfully completed in all the 24 cases, with a mean operation time of 175 (100－285) min, intraoperative blood loss of 200 (50－800) ml, hemoglobin decrease of 25 (4－57) g/L on the first day after surgery, postoperative drainage tube indwelling of 3 (2－7) d, and urinary catheterization of 12 (4－18) d. Six (25%) of the patients received intraoperative blood transfusion, 1 underwent transurethral electrocoagulation hemostasis 1 month after surgery because of postoperative bleeding, and 1 received transurethral resection of the cicatrical adhesive tissue of the bladder neck 12 months after surgery. No other complications occurred postoperatively. The IPSS (3 ［1－7］), Qmax (19.6 ［9.9－32.1］ ml/s), PVR (0 ［0－34.9］ ml) and QOL score (2 ［0－3］) of the patients were significantly improved after surgery (P < 0.05), but no statistically significant differences were observed in the IIEF (20 ［19－24］) and MSHQ scores (14 ［13－14］) as compared with the baseline (P > 0.05). CONCLUSION: Trans-Douglas RSS-RASP is a safe and effective minimally invasive method for the treatment of large-volume (>80 ml) BPH, which can improve the urinary function of the patient after operation.

Structural Characteristics of Reaction Tissue in Plants.

To maintain or adjust posture under the challenges of gravity and increased self-weight, or the effects of light, snow, and slope, plants have the ability to develop a special type of tissue called reaction tissue. The formation of reaction tissue is a result of plant evolution and adaptation. The identification and study of plant reaction tissue are of great significance for understanding the systematics and evolution of plants, the processing and utilization of plant-based materials, and the exploration of new biomimetic materials and biological templates. Trees' reaction tissues have been studied for many years, and recently, many new findings regarding these tissues have been reported. However, reaction tissue requires further detailed exploration, particularly due to their complex and diverse nature. Moreover, the reaction tissues in gymnosperms, vines, herbs, etc., which display unique biomechanical behavior, have also garnered the attention of research. After summarizing the existing literature, this paper provides an outline of the reaction tissues in woody plants and non-woody plants, and lays emphasis on alternations in the cell wall structure of the xylem in softwood and hardwood. The purpose of this paper is to provide a reference for the further exploration and study of reaction tissues with great diversity.

Effects of Accelerated Ageing by Humidity and Heat Cycles on the Quality of Bamboo.

The effect of humidity and heat environmental conditions on the durability of conventional bamboo materials is a pressing issue in the reserving phase of biomass materials. In this study, the relationship between the main physicochemical, pyrolytic, and mechanical properties of bamboo before and after ageing has been investigated. Exposure of engineered bamboo raw materials with moisture content up to 10% to alternating humidity and heat cycles (20 °C 98% RH-30 °C 64% RH-40 °C 30% RH) of ageing (HHT) causes degradation of the chemical polymer matrix. Byk Gardner 6840 color difference meter, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), compression intensity, thermogravimetric-infrared spectroscopy (TG-IR), and density changes are used to assess the quality of the material before and after ageing. No significant changes in the moisture content within the range of 6.12 ± 0.327 after two weeks of the engineered bamboo during wet thermal cyclic ageing were determined. However, there were significant differences in mass loss (7.75-9.93 g), cellulose crystallinity, chemical changes, compression strength, and pyrolytic properties. Differences in specimen colors were observed during 10 weeks of the accelerated humidity heat cycling ageing, and TCD variations ranged from 3.75 to 20.08 and from 0.25 and 3.24, respectively. Reduced cellulose crystallinity (36.459-22.638%), axial compressive strength (63.07-88.09 MPa), and modulus of rupture (2409-4286 MPa) were found during aging, whereas deformation and ductility properties were improved. Both natural and humidity heat ageing improve thermal stability and peak pyrolysis rates (0.739-0.931; 0.731-0.797). Humidity heat cyclic ageing will assist in the design and risk assessment of warehousing environments for industrial applications.

Effect of Rosin Modification on the Visual Characteristics of Round Bamboo Culm.

Rosin was used to treat round bamboo culm using the impregnation method. The quantitative color and gloss measurements combined with a qualitative eye tracking experiment were used to evaluate the effect of rosin treatment under different temperatures on the visual characteristics of the bamboo surface. Surface morphology analysis was also used to explore the mechanism of modification. The results showed that proper heating of the modified system was conducive to the formation of a continuous rosin film, which increased the gloss value. The maximum gloss value of 19.6 achieved at 50 °C was 122.7% higher than the gloss value of the control group. Heating decreased the brightness of the bamboo culm and changed the color from the green and yellow tones to red and blue. Additionally, at temperatures higher than 60 °C, the bamboo epidermal layer was damaged or shed, and stripes formed on the culm surface. The density of these stripes increased with an increase in treatment temperature. Eye movement experiment and subjective evaluation showed that high gloss would produce dazzling feeling, such as at 50 °C, while low gloss will appear dim, such as at 80 °C, while the gloss at 40 °C and 60 °C were appropriate. Additionally, the solid color surface below 60 °C had a large audience of about 73%, and the striped surface above 60 °C was preferred by 27% of the subjects.

Bamboo's tissue structure facilitates large bending deflections.

Bamboo is becoming increasingly popular as an engineering material and source of bio-inspiration for instance in architecture and for the manufacture of a variety of woven products. Besides the properties of bamboo products for construction purposes, the bending deformability of thin bamboo slivers is of interest, as it appears that extraordinary large deflection can be achieved. To unravel the underlying mechanisms that may contribute to the high deformability at the tissue and cell level, bending deflection tests and additionalin situexperiments were performed to record the deflection of bamboo slivers in dependence of the tissue composition and the deformations of individual cells. For the latter, a simple bending deflection setup was used employing micro-CT measurements to analyze the deformation of individual parenchyma cells (PCs), fiber bundles and vessel elements at different stages of bending deformation of the bamboo slivers. The results showed that the degree of displacement and the characteristic fracture behavior strongly depend on the volume fractions of PCs and fibres determined by the position in the bamboo culm. For slivers with a sufficiently high fibre volume content, the very high bending deformability could be facilitated by the deformation of PCs, which are squeezed between the fibre bundles during increasing bending deflection.

Water vapor sorption behavior of bamboo pertaining to its hierarchical structure.

Bamboo is an anisotropic, hierarchical, and hygroscopic material. Moisture transport in bamboo is one of the most fundamental properties affecting almost all other physical and mechanical properties of the material. This study investigated the water vapor sorption behaviors of bamboo at various structural levels: cell walls, cells (with pits) and bamboo blocks. The specimens with two sorption directions, longitudinal (L) and transverse (T), were measured by saturated salt solution method and dynamic vapor sorption. The parallel exponential kinetics model was used to analyze the sorption kinetics. The results showed that at the cell wall level, the sorption rate and equilibrium moisture content (EMC) of cell wall in the L specimens were larger than those in the T specimens. The differences were probably caused by the looser cell wall layers in the L specimens. At the cellular scale, pits in the cell wall resulted in an enhanced sorption rate and EMC of the T specimens compared with the L specimens where the pits in the parenchyma cells were only distributed in the lateral walls but not in end walls. At the macro scale, the sorption rate and moisture content of bamboo blocks were largely controlled by the vessel cells. As a hierarchically-structured plant, bamboo performs the biological function of moisture transport at all these scales. This work helps improve the understanding of water transport behavior in bamboo, which may lead to better bamboo drying and impregnation processes.

Quantitative Visualization of Weak Layers in Bamboo at the Cellular and Subcellular Levels.

Weak layers in bamboo, which are prone to the generation of cracks or are the preferred routes for crack growth, govern the machining processes and applications of bamboo. Weak layers are avoided during storing but are utilized during splitting and slicing. Gaining an understanding of the weak layers is a priority that will allow for the determination of whether to avoid or utilize them. In this study, scanning electron microscopy was used to observe the weak layers at the cellular and subcellular levels. A nanoindentation instrument and a Raman microscope were used to quantitatively characterize the mechanical properties and chemical components of these weak layers. The results show that among the three types of bamboo cells, vessel cells were the most vulnerable to damage, while fiber cells were the least susceptible to damage. The weak layers at the subcellular level were compound middle lamella (CML), thin layers of cell walls, and pits. The average storage modulus values were as follows: 13.7 GPa for CML, 17.0 GPa for pits, 20.6 GPa for thin layers, and 25.3 GPa for thick layers. Compared with the thick layers, the maximum decrement of cellulose content was 51% in CML and 41% in thin layers. With the lowest cellulose content, CML was the likeliest subcellular structure in which cracks propagated. The hardness of the pits was lower than that of the adjacent non-pit areas. The mechanical properties of bamboo increased by targeted modification of the weak layers. This work demonstrates a comprehensive investigation into weak layers of bamboo and quantitatively visualizes their mechanical and chemical properties.