Manufacturing and Characterization of Wide-Bundle Bamboo Scrimber: A Comparison with Other Engineered Bamboo Composites

Controlling the variability in mat structure and properties in bamboo scrimber (BS) is key to producing the product for structural applications, and wide strip scrimber (WBS) is an effective approach. In this study, the effects of scrimmed bamboo bundle morphology and product density on the properties of WBS were investigated. WBS panels were manufactured and tested using wide (200 to 250 mm) bamboo strips with different fiberization intensity. Maximum strength properties (flexural, compressive, and shear strength), and lowest thickness swelling and water absorption were achieved with three or four passes due to the higher resin absorption by strips. For balanced product cost and performance, we recommend 1–2 fiberization passes and a panel density of 0.9–1.0 g/cm³. Panel mechanical properties were compared with other common bamboo composites. Bamboo scrimber products were highly variable in properties due to differing manufacturing processes, element treatments, and suboptimal mat structure. Products including laminated bamboo lumber and flattened bamboo made from nonfiberized elements show markedly different relationships between strength and elastic properties mostly due to inadequate bonding between the laminae, which causes premature bond-line failure. This study helped improve the understanding of the structure–property relationship of engineered bamboo products while providing insights into process optimization.     

Probability Distribution Characteristics of Horizontal and Vertical Mechanical Properties of Rubber Bearings

Rubber bearings are widely used to protect civil structures from destructive earthquakes. The mechanical properties of the bearings are the key technical parameters that determine the seismic isolation performance of isolated structures. To estimate the probability distribution of the mechanical properties related to rubber bearings (including horizontal stiffness, vertical stiffness, post-yield stiffness and yield force) under seismic events. Typical natural rubber bearings (NRBs) and lead-core rubber bearings (LRBs) were designed and fabricated, and the bearings were subjected to repeated load tests using a compression-shear testing machine. The test results of the horizontal and vertical mechanical properties of the bearings in the tests were basically consistent with the design values, and the rubber bearings showed stable mechanical behavior under repeated cyclic loading. The statistical analysis of the test results revealed that the relevant mechanical properties of the NRB and LRB specimens followed a lognormal or general extreme distribution with coefficients of variation mainly ranging from 0.86% to 5.6%. The dispersion of the yield force of LRB was the largest in the repeated tests of many mechanical parameters of typical rubber bearings.     

Strain Measurements within Fiber Boards. Part I: Inhomogeneous Strain Distribution within Medium Density Fiberboards (MDF) Loaded Perpendicularly to the Plane of the Board

Internal bond strength testing is a widely used approach for testing quality traits of wood based panels. Generally, failure of internal bond specimens is due to adhesion and/or wood failure in the specimen. It has been reported that a composite product with a large variation in the vertical density profile fails in the center part of the board which is either the middle of the core layer or the transition zone between core layer and face layer. The density in the failure zone is typically 50% lower than the maximum density in the face layers. The aim of this study was to analyze the strain distribution in a specimen under tension perpendicular to the panel plane. The results showed that a high variety of strain magnitude occurred in the specimen. The strain is either aligned with the tension direction or a tension zone is built in one of the edge zones leading to failure. Vector graphics of the specimen show the problematic test setup of internal bond strength measurement. Strain spots in the edges lead to the assumption of an uneven stress distribution due to the momentum which results from non-perfect alignment or irregularities in the test setup.     

Distribution of Apolipoprotein E Isoforms between Very Low and High Density Lipoproteins of Normal Subjects and Hyperlipidemic Patients with Special Reference to Type III Hyperlipidemia

ABSTRACT Serum very low (VLDL) and high density lipoproteins (HDL) from 17 hyperlipidemic patients and 10 normal subjects have been isolated by preparative ultracentrifugation, and the electrophoretic patterns of apolipoprotein E (apo E) isoforms in the lipoproteins have been examined by isoelectric focusing. Type III hyperlipidemia (dyslipoproteinemia) has been suggested to be a disease caused by an abnormal mutant of the apo E-3 isoform. In accordance with this, all patients with type III hyperlipidemia in the present study showed lack of apo E-3 in VLDL. However, all these patients demonstrated a protein zone corresponding to apo E-3 in their HDL fraction. Patients with other types of hyperlipidemia or normal subjects who showed an apo E-4 variant in VLDL had an HDL that lacked apo E-4. The results support the hypothesis that type III hyperlipidemia is due to an abnormal composition of the VLDL particles rather than a result of an abnormal mutant of apo E-3.     

家兔体内低密度脂蛋白受体分布的免疫荧光研究

以本实验室制备的两种抗兔低密度脂蛋白受体单克隆抗体，进行间接免疫荧光染色，观察此种受体在兔各种组织中的分布。结果显示，肝细胞、肾上腺皮质细胞的特异性免疫荧光最强；卵泡细胞、黄体细胞、肠道及支气管上皮细胞和表皮基底细胞等都显示较强的免疫荧光；心肌、骨骼肌、肾上腺髓质及结缔组织的荧光很弱，而脑实质几乎无荧光反应。提示低密度脂蛋白受体活性可能与组织的生理功能和代谢特性有关。