This paper presents a new kind of composite produced with small-diameter bamboo (Phyllostachys glauca McClure) and extruded tubular particleboard. The mechanical properties of the composite are ...significantly affected by the properties of the bamboo. First, the compression strength of the bamboo was studied. It was found that the compression strength (fc, MPa) and the maximum force of compression (Fmax, kN) of the bamboo are strongly, linearly related to its outer diameter (D, mm): fc = -0.5D+79.37 and Fmax = 0.83D–0.59. The compression strength of the composite made with the bottom part of the bamboo was larger than that of composites made with the middle and top parts. In addition, its reliability was also the best of the three groups due to the variation of the outer diameter of the bamboo from the bottom to the top. The bottom part of the bamboo is the best choice for manufacturing bamboo-reinforced extruded particleboard (BREP).
Non-destructive evaluation (NDE) techniques have been shown to be effective for evaluating mechanical properties of wood-based materials. In this study, transverse vibration of a beam under the two ...ends free boundary condition (FBV) was employed to measure the modulus of elasticity (MOE) in different strength directions of laminated strand lumber (LSL). It was found that the MOE values measured by the FBV were slightly higher than those measured using the three-point bending test (TPB), and the correlation coefficients between the MOE values along the major and minor strength directions measured by the two methods were 0.845 and 0.938, respectively. The effect of the length/depth ratio on measured MOE values by the FBV method was also investigated. With the decrease in the length/depth ratio of LSL, the measured MOE in the major and minor strength directions decreased. The results of the ANOVA test showed that the length/depth ratios had a significant effect on the measured MOE. The experimental values of MOE of LSL in the diagonal strength direction matched well with the theoretical values calculated by the Hankinson-type formula.
Mechanical welding technology has been widely employed in the making of bonding joints with wood. Moso bamboo, a lignocellulosic biomaterial, can also be bonded using mechanical welding technology. ...The surface response methodology was used to define welding parameters yielding optimal joint strength. In the range of this experiment, it was found that the vibration amplitude and the welding pressure both had a significant influence on the performance of the joint, while the welding time did not. The quadratic model was able to significantly fit the actual results and could be used to determine and optimize the bonding strength.
The primary aim of this study is to characterize long-term quality of life (QOL) in patients with esophageal and gastroesophageal junction (EGEJ) cancers who underwent curative intent treatment. EGEJ ...survivors were recruited to participate in a one-time cross-sectional survey study using validated questionnaires assessing QOL. Chart review was conducted for patient demographics and clinical characteristics. Spearman correlation coefficients, Wilcoxon signed-rank test, and Fisher's exact test were used to assess relationships between patient characteristics and long-term outcomes. QOL was relatively high in this sample, as evidenced by high median scores on the functional scales and low median scores in the symptom domains of the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-C30, with an overall median global health score of 75.0 (range 66.7-83.3). Patients using opiates at the time of survey reported lower role functioning (P = .004), social functioning (P = .052), and overall global health (P = .041). Younger patients had significantly higher rates of reflux (P = .019), odynophagia (P = .045), choking (P = .005), and cough (P = .007). Patients using opiates or of younger age had lower QOL and higher symptoms in this cohort of long-term EGEJ survivors.
High voltage electrostatic field (HVEF) was applied in order to improve wood surface characteristics, bonding and mechanical properties of wood composites. Masson pine (
Pinus massoniana Lamp.
) ...plywood and laminated veneer lumber (LVL) were selected in this study. Surface characteristics were conducted by the electron spin resonance (ESR) and X-ray photoelectron spectra (XPS). Bonding interphase and mechanical properties were investigated by fluorescence microscopy and vertical density profile (VDP), bonding strength, wood failure ratio, MOE and MOR. The results indicated that more increments were obtained in free radicals, O/C ratios and C2-C4 components. This is because electrons broke more wood chemical groups and new ions occurred among wood surface under HVEF. Significantly decreased PF adhesive penetration depth (PD) and increased density at bonding interphase was achieved in HVEF treated composites. More decrease of PD and increment of density were observed in plywood than that of LVL. This was attributed to cross linked wood fibers among bonding interphase in plywood. Mechanical properties of bonding strength, wood failure ratio, MOE and MOR were significantly increased under HVEF treatment both for two composites. Higher bonding strength, MOE and MOR were obtained in plywood and their increments were as 98.53%, 33.33%, 18.55% and 12.72%.
The insulated predictions were carried out for LVL, CLT and HCLT in order to evaluate their sound properties, in which the theoretical value of sound insulation was predicted by regarding the ...substances in wood cell wall as equivalence to specific medium based on Biot model, and the wood anatomical characteristics, such as the length and diameter of tracheid, diameter of pit, and porosity, were taken into account for determining the equivalent density and bulk modulus of elasticity of wood cell wall. By comparing the tested and predicted values of sound insulation, the conclusion were drawn as follows: the predicted values of sound insulation were significantly correlated with the tested values for LVL, CLT and HCLT. As for Masson pine and Southern pine, the adjacent of earlywood and latewood was considered as sandwich structure for the calculation of sound insulation. Meanwhile, the bonding interface was creatively introduced to improve the accuracy of sound insulation prediction. The transfer function involved in sound insulation prediction provide an effective method to characterize the sound insulation volume of wood composite in construction and decoration areas.
Gully initiation has been a subject of much discussion in the field of gully erosion. Gully initiation could be examined by the S-A relationship (S = aA
−
b
) between the critical slope of the gully ...head (S) and the upstream drainage area (A). Gully erosion plays an important role in sediment yield and land degradation in the Dry-hot Valley region of Southwest China; however, little research has focused on gully development in this region. This study investigated gully morphology and the critical topographic threshold of permanent gullies in Yuanmou Dry-hot Valley. Data for 36 gully heads were derived from the gully digital elevation model created by high-precision real-time kinematic GPS (RTK GPS). A significant relationship between gully length and volume (r
2
= 0.77, p < 0.01) was found to exist, indicating that gully length can be used to estimate the gully erosion rate. Additionally, as vegetation coverage inside the gully increases, the gully morphology tends to be stable. The S-A relationship was S = 0.5195A
−.0899
, while AS
2
values ranged between 4.2 and 758.5 m
2
. The low value of constant b (0.0899) indicates that collapse of the gully wall is the dominant process of gully erosion in Yuanmou Dry-hot Valley.
This study investigated the effect of R-value (the ratio of -NCO to -OH) and addition content of blocked polyurethane prepolymer (BPUP) on the properties of melamine-urea-formaldehyde (MUF) ...particleboards made from high-moisture particles (25wt%). Eight types of particleboards (A, B, C, D, E, F, G, H/D, I) were made with various BPUP contents (0, 4, 6, 8, 10wt%) and R values (R=3, R=4, R=5, R=6). The dimensional stability and mechanical properties of the particleboards were improved by adding BPUP to MUF resin. With the increase in R-value and BPUP concentration, particleboards showed relatively better dimensional stability and mechanical properties. Best results were obtained with Board H (92:8, R=5) with thickness swelling of 13.1% and water uptake of 25.7%. The recording statistics in Board H have identified an optimum internal bond strength value of 0.83MPa, which was 59.6% higher than Board F (96:4, R=5) and 159.4% higher than only MUF bonded particleboard. It was also found that increasing R-value and the proportion of additional BPUP showed positive effects on the flexural properties of MUF particleboards. Besides, the function relationship among mechanical properties was obtained to investigate correlation between thickness swelling (TS) and internal bond strength (IB), modulus of elasticity (MOE) and modulus of rupture (MOR).
Under conventional processing conditions, the resistivity of wood dust is in the range of insulating materials, which can induce a dust cloud explosion when there are static sparks. This paper took ...the fast-growing poplar wood commonly used in Chinese wood processing and studied the effects of moisture content, temperature, and particle size on the electrical resistivity value of sanded wood dust. Orthogonal analysis was conducted on the influencing factors. The results showed that the influence of moisture content on electrical resistivity was the most significant factor, followed by temperature and particle size. Further experiments have shown that when the moisture content increased from 6% to 32%, the resistivity decreased from 10
Ω cm to 10
Ω cm, which reached the suitable resistivity range of static discharge method. The ion concentration of wood dust extracted in cold water and hot water and the resistivity of poplar dust residue after extraction were determined. Nine metal ions (a total of 105.02 mol/g) were detected in cold-water extract, and the concentrations of K
, Na
, Mg
and Ca
accounted for 99.8%. The original poplar dust and the extracted poplar dust were measured and analyzed. The changes in water-soluble ion content, functional groups, crystallinity, and complexes of the wood dust before and after ion dissolution, jointly led to changes in the electrical resistivity of the wood dust (a difference of 2-4 orders of magnitude). It was verified that the way wood dust conducts electricity is through ion conduction. There were more abundant capillary system structures between poplar dust particles, allowing water-soluble ions to move more freely with water channels. The larger specific surface area and higher temperature also promoted the dissolution of water-soluble ions, which affected the electrical resistivity.
Chiral separation of 20 pairs of amino acids derivatized with fluoresceine-5-isothiocyanate (FITC) by capillary electrophoresis and laser-induced fluorescence detection was studied using the mixture ...of β-cyclodextrin (β-CD) and sodium taurocholate (STC) as selector. Resolution was considerably superior to that obtained by using either β-CD or STC alone. The molar ratio of β-CD to STC of about 2:3 was found to be critical to achieve maximum separation. At this β-CD-to-STC ratio, chiral separation occurred at really low total concentration of β-CD and STC (<0.1 m
M). Other impacting factors were investigated including the total concentration of β-CD and STC, pH, and capillary conditioning procedure between two successive runs. Using a running buffer of 80 m
M borate containing 20 m
M β-CD and 30 m
M STC at pH 9.3, all of the 20 pairs of FITC-amino acid enantiomers were baseline resolved. The resolutions of the most pairs of the amino acid enantiomers (17 of 20) were higher than 3.0, only three pairs gave a resolution lower than 3.0 but higher than 1.90 (β-phenylserine, pSer). The highest resolution reached 14.58 (Glu). Two derivatives of β-CD, 2-hydroxypropyl-β-CD (HP-β-CD) and heptakis(2,6-di-
O-methyl)-β-CD (DM-β-CD) were also explored. HP-β-CD showed similar cooperative effect with STC, while DM-β-CD together with STC led to poorer chiral separation.
PDF
