Bamboo Section Research Articles

Strength analysis of bamboo by microscopic investigation of bamboo fibre

This paper presents the mechanical properties of two bamboo species, namely Mao Zhu and Kao Zhu, which are commonly used for scaffolding in Southern China. Variations of the compressive strength against the physical properties of bamboo along the culms for both bamboo species were compared. A correlation of the average number of vascular bundle to the compressive strength of both bamboo species was developed. Findings indicate that the compressive strength of both Kao Zhu and Mao Zhu ranged between 45 and 65 N/mm 2 and the compressive strength of top section bamboo was higher than the bottom section. The fibre area of the top section bamboo was also found to be greater than bottom section bamboo from microstructure count of the sclerenchyma fibre within the vascular bundle of bamboo section. The microscopic examination of sclerenchyma fibre of bamboo section can be an alternative measure of the strength of bamboo for construction use.

Effects of vascular fiber content on abrasive wear of bamboo

Natural biomaterials have unique structures and some distinguishing properties for adapting themselves to natural surroundings. Bamboo is a natural composite reinforced with longitudinal fibers (vascular fibers). The abrasive wear property of the cross section of bamboo ( Phyllostachys pubescens) stem was examined. The abrasive material used for tests was the mixture of quartz sand (96.5 wt.%) and powdered bentonite (3.5 wt.%) and contained a water content of 3 wt.%, simulating soil condition The size of the quartz sand particles was 0.104–0.214 mm, 0.214–0.420 mm and 0.420–0.840 mm, respectively. The abrasive wear tests were run on a rotary disk type of abrasive wear testing machine. The relative sliding velocity was 1.68, 2.35 and 3.02 m/s, respectively. It was concluded that the abrasive wear resistance of the cross section of the bamboo stem was a function of the vascular fiber content of bamboo, the abrasive particle size and the relative sliding velocity. The wear resistance of bamboo was increased with its vascular fiber content. A higher sliding velocity or a larger abrasive particle size resulted in a higher abraded volume of bamboo. The effects of the tensile strength and the impact strength of bamboo on its abrasive wear were discussed. It was found by scanning electron microscopy that the geometric morphology of the abraded surfaces of the sections of bamboo stem displays a not-smooth structure. This not-smooth surface morphology provides a clue to develop anti-abrasion morphological surfaces of soil-engaging components.

タケノコのかっ変発生に関与する数種酵素活性の貯蔵中の変動

The changes in glucose-6-phosphate dehydrogenase (G6PDH), shikimic acid dehydrogenase (SADH), phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL) and polyphenol oxidase (PPO) activities of bamboo shoots during storage at 20°C were examined in relation to their browning. 1. Determination of G6PDH, SADH and PPO activities in the three sections of bamboo shoots revealed that G6PDH and SADH were the highest in the apical section and the least in the basal section, and also that G6PDH activity was the highest among the three enzymes, while PPO maintained nearly the same activity in the three sections. 2. After 2 days in storage, G6PDH and SADH activities of bamboo shoots increased to about 1.3 and 1.7 times those of the initial day, respectively, then decreased over 9 days as browning increased. Meanwhile PPO activity increased slightly after 2 days, then decreased. 3. PAL activity of bamboo shoots was the highest in the basal and the least in the apical sections. TAL activity in all sections was quite low, compared to PAL activity but they exhibited the same trends. 4. Both PAL and TAL activities in the basal section of bamboo shoots decreased after 2 days, then stayed at the same level ; after 9 days they increased rapidly.

Hierarchical Functionally Gradient Structures of Bamboo, Barley, and Corn

Bamboo and certain other plants have excellent characteristics based on functionally gradient structures. Figure 1 shows a cross section of bamboo, corn, and barley culms. The collection of solid dots in bamboo is called the bundle sheath, which acts as fibers for the plant. These bundle sheaths are shown in the magnified photograph of corn and barley. These two plants are made of composite materials reinforced by fibers of the bundle sheath; the fiber strength is about 10 times that of the matrix. Furthermore, the fiber distribution is dense in the outer region and sparse in the inner region. It can be said that the fiber distribution forms a gradient structure. The fibers in barley are sparse in the narrow cross section and are different from the fibers in corn and bamboo. The number of honey-comb-shaped cells in barley is higher on the outside than the inside region. Therefore, barley also has a gradient structure. These relations of the microscopic gradient structure are displayed graphically by the cross-sectional photographs. Figures 1a and 1b present the fiber contents of bamboo and corn, respectively, with respect to radius measured from the outer radius. Figure 1c gives the gradient distribution of the cell number for barley with respect to radius. These gradient features probably relate to the bending-stress distribution caused by wind, rain, and snow—the so-called environmental loads.

Microstructure based statistical model of electromigration damage in confined line metallizations in the presence of thermally induced stresses

Probability distributions are evaluated for electromigration induced open failures in narrow, passivated interconnects with a near-bamboo grain structure. Void formation is initiated at the cathode ends of the polycrystalline line segments or ‘‘grain clusters.’’ If these clusters are longer than a critical size Lc, they can accommodate enough atoms for voids to reach the critical size to fail the line. Obviously, the critical size Lc depends on the thermal stress: a cluster under a tensile stress is able to incorporate more atoms from the void than an unstressed cluster. In the case the clusters are shorter than Lc, atoms from the voids must be distributed also to bamboo sections, outside the clusters, in order for the voids to induce open failures. Based on this physical picture, failure probabilities are evaluated as a function of time. The predicted failure distributions and parametric dependencies compare well with the experiments.

Bionomics of Sabethes chloropterus Humboldt, a vector of sylvan yellow fever in Middle America.

Summary A colony of S. chloropterus was established in 1-meter cubical cages. A trussed guinea pig or rhesus monkey served as the source of blood for the females, while a cotton ball soaked in sugar solution and hung from the top of the cage made available the necessary carbohydrates for both males and females. A well-ripened section of bamboo closed with a lid and with a 1-inch hole through its side was used as an oviposition receptacle. Larvae were reared in round enamel pans 10 inches in diameter in a yeast-infusion medium. S. chloropterus was found to be strictly diurnal in habits. Females seek a blood meal in greatest numbers during the early afternoon hours (1400–1500). Both males and females become engorged on sugar solution from 6 to 24 hours after emergence. No female has been observed feeding on blood before the fifth day after emergence and the peak of biting activity is not reached until the second or third week. Females prefer to bite high on the body having a special predilection for the nose and lips. S. chloropterus is a stenogamic species. Mating occurs while resting on a surface and is preceded by peculiar prenuptial activity on the part of the males. Copulation lasts from 4 seconds to 34 minutes, with an average time of 6 minutes. Mating has not been observed before the sixth day after emergence and the peak of mating activity is not reached before the second or third week of the female's life. Insemination does not necessarily occur before the first blood meal and does not appear to be essential for ovarian development. Females oviposit by hovering in front of the hole in the bamboo section and forcibly ejecting one or two eggs through the hole and into the water in the bamboo. The position of the sun in the sky rather than light intensity seems to be the determining factor in inducing oviposition. The greatest percentage of eggs are laid in early afternoon (hours 1200–1500). The species was found to be nonautogenous, that is to say, it must have a blood meal before egg-laying takes place. Oviposition usually begins on the third day after a blood meal and goes on through the thirteenth day. The average number of eggs per female after a single blood meal is 38.6 with a minimum of 2 and a maximum of 103. Each female may lay an average of 138 eggs during her life time. Females exercise a definite preference for ovipositing in a bamboo with closed top and a 1-inch hole through the side rather than in a bamboo with open top. The eggs of S. chloropterus are rhomboid in shape, the embryo develops in 3 to 4 days at room temperature and the eggs hatch soon after the larvae attain full development inside, being incapable of going into a prolonged diapause. The larvae are facultatively predaceous and cannibalistic but they do not frequently attack larvae of their own species, when in the same stage of development. They do not swallow the prey but suck the body contents through punctures in the cuticle. The mean period spent by larvae from hatching to pupation at 26°C, is 14.8 days with a maximum of 28 days and a minimum of 9 days. The mean developmental period of pupae at this temperature is determined to be 150 hours with a maximum of 160 hours and a minimum of 123 hours. The mean life span of females after the initial blood meal at mean temperatures of 26.1 to 26.8°C and a mean relative humidity of 92 to 97%, was found to be 38.9 days with a maximum of 140 days. It was also determined that 50 per cent of these females live between 5 and 6 weeks after taking their first blood meal and that 9 to 10 weeks elapsed before 90 per cent of these females died.