A new method for estimating stiffness and strength in bolted timber-to-timber joints and its verification by experiments (II): bolted cross-lapped beam to column joints

Bolted cross-lapped joints (BCLJs) are one of the basic jointing methods used in Japan and European countries. There are, however, some problems in the design of BCLJs. With increasing use of large-scale wooden frame structures in Japan, it is necessary to establish proper estimating methods for predicting actual characteristics. A new approach was developed, using Saint Venant torsion theory, to estimate the performance of bolted timber joints in a more practical manner than using computer simulations. The calculated values were compared with the experimental results, indicating that the rotational stiffness and yield moment of BCLJs would be precisely predicted using the proposed theory. It was also found that the rotational stiffness calculated using the design method rooted on Coulombs torsion theory is about two times higher than the experimental results in the case of a rectangular arrangement of bolts.     

In-plane shear properties of the wood-based sandwich panel as a small shear wall evaluated by the shear test method using tie-rods

 The fundamental in-plane shear properties were investigated for the wood-based sandwich panel of plywood-overlaid low-density fiberboard (SW) manufactured at a pilot scale to develop it as a shear wall. The shear test method using tie-rods standardized for shear walls was applied to SW with dimensions of 260 mm square and 96 mm thick as a small shear wall and to plywood (PW) and thick low-density fiberboard (FB). The shear modulus and shear strength of PW, FB, and SW were determined. To measure the shear deformation angle, a displacement meter and strain-gauge were used. The shear moduli of PW (0.68 g/cm³) and FB (0.25–0.35 g/cm³) were 460 and 21–58 MPa/rad, respectively. The shear modulus of SW as a composite was analyzed. Some experimental models of SW were proposed (i.e., rigid-α, rigid-β, flexible, and semirigid models). The shear modulus of SW (0.35–0.40 g/cm³) evaluated based on the rigid-α and semirigid models were 73–89 and 109–125 MPa/rad, respectively. The theoretical shear modulus of SW was calculated to be 110–129 MPa/rad. Received: May 9, 2001 / Accepted: June 26, 2002 RID="*" ID="*" Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, Japan, April 2000; and the 5th Pacific Rim Bio-Based Composite Symposium, Canberra, Australia, December 2000 Acknowledgments The authors express our deep gratitude to Mr. Noritoshi Sawada (Hokushin Co.), Dr. Wong Cheng, and their cooperative members for their expert technical support for the preparation of manufacturing the thick fiberboard and sandwich panel. We are grateful also to Drs. Min Zhang, Kenji Umemura, Wong Ee Ding, and Guangping Han for their great help and advice in manufacturing the thick panels. The authors are grateful to Hokushin Co. for the fiber and resin and to Ishinomaki Gouhan Co. for the plywood. We thank Mr. Makoto Nakatani for his expert assistance when preparing the specimens for the shear test. Funding provided by the Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists as a JSPS Research Fellow is also gratefully acknowledged.     

Regeneration growth in different light environments of mixed species, multiaged, mountainous forests of Romania

Growth of regenerating trees in different light environments was studied for the mountainous, mixed-species forests in the Carpathian Mountains of Romania. The primary species in these mixtures were silver fir (Abies alba Mill.), European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst). Seedlings/saplings of these species were selected and measured in different stands from two different geographical locations. Regenerating trees were measured for height and diameter growth during the summer of 2002. For each seedling/sapling, percentage of above canopy light (PACL) and stand basal area (BA) were used to assess available and occupied growing space respectively. Regeneration growth was compared against these two variables and regression relationships were developed. Using these models, we predicted the dynamics of regeneration as both growth and species composition. Our results showed that in low-light environments (PACL<20–35%; BA>30 m²/ha), shade tolerant fir and beech clearly outcompeted the spruce. Therefore, in dense stands, spruce could be eliminated by the shade tolerant species. For intermediate levels of cover (PACL=35–70%; BA=15–35 m²/ha) the spruce grew at comparable rates as the beech and fir. All three species showed similar growth rates in open conditions (PACL>80–90%; BA<15–20 m²/ha) with the spruce having a tendency to outgrow the others. However, in terms of establishment, such conditions favor spruce and inhibit fir and beech.     

Anticholinergic effects of artemisinin, an antimalarial drug, in isolated guinea pig heart preparations

Concern has been growing about the cardiac toxicity of antimalarial drugs. Artemisinin, a unique type of antimalarial drug originating from a Chinese medicinal plant, has minimal adverse effects, but it has been reported to inhibit delayed rectifier potassium current, a voltage-gated potassium current. However, no studies have been published concerning the effect of artemisinin on ligand-gated potassium currents. Therefore, in the present study, we examined the influence of artemisinin on the acetylcholine receptor-operated potassium current (IK.ACh), a ligand-gated potassium current, in guinea pig atrial myocytes using a patch clamp technique. Artemisinin (1 to 300 microM) inhibited I(K.ACh) induced by extracellular application of both carbachol (1 microM) and adenosine (10 microM) and that induced by intracellular loading of GTPgammaS (100 microM) in a concentration-dependent manner. Artemisinin inhibited carbachol-induced, adenosine-induced, and GTPgammaS-activated IK.ACh within almost the same concentration range. In left atria, artemisinin (1 to 100 microM) partially reversed the shortening of action potential duration induced by carbachol in a concentration-dependent manner. Carbachol-induced negative inotropic action in left atria was also inhibited by artemisinin (10 to 300 microM). In conclusion, we suggest that the anticholinergic action of artemisinin is mediated through inhibition of IK.ACh via inhibition of the muscarinic potassium channel and/or associated GTP-binding proteins.     

Involvement of stathmin in proliferation and differentiation of immortalized human endometrial stromal cells

Uterine endometrial stromal cells differentiate into decidual cells during the late secretory phase of the menstrual cycle and pregnancy. However, the biochemical mechanisms of decidualization have yet to be definitively elucidated. In the present study, we transfected primary human endometrial stromal cell with a temperature-sensitive mutant of simian virus 40 large T antigen and thereby established an immortalized stromal cell line (EtsT) in order to examine the role of stathmin, a cytosolic phosphoprotein that regulates microtubule dynamics, in stromal cell differentiation. When treated with the decidual stimulus dibutyryl-cAMP (db-cAMP) or forskolin, the fibroblastic cell-shaped EtsT cells transformed into large- and round-shaped cells and secreted large amounts of the decidual markers prolactin (PRL) and insulin-like growth factor binding protein-1 (IGFBP-1). Analysis of the stathmin protein levels in the db-cAMP- and forskolin-treated EtsT cells revealed that the total and phosphorylated protein levels dropped as decidualization progressed. Suppression of stathmin expression by transfection with small interfering RNA (siRNA) suppressed EtsT cell proliferation. It also abolished db-cAMP-induced PRL and IGFBP-1 mRNA expression and protein secretion. Thus, stathmin expression can be considered an integral factor regulating the initial stage of the process of human endometrial stromal cell differentiation.     

The interaction between orally administered non-steroidal anti-inflammatory drugs and prednisolone in healthy dogs

The interaction between oral non-steroidal anti-inflammatory drugs (NSAIDs) and prednisolone administered concurrently for 30 days was studied in 18 healthy dogs divided into 3 groups of 6 dogs each: a drug-free negative control group (NC group) given 2 gelatin capsules; a group given meloxicam (0.1 mg/kg) and prednisolone (0.5 mg/kg) (MP group); and a group given a reduced dosage of ketoprofen (0.25 mg/kg, p.o.) and prednisolone (0.5 mg/kg, p.o.) (KP group). The dogs were periodically monitored by physical examinations, blood analyses, endoscopic examinations, fecal occult blood tests, renal function tests [effective renal plasma flow (ERPF) and glomerular filtration rate (GFR)], urinalyses [urinary sediments, and urinary micro-albumin to creatinine ratio (UAlb/Cre)], urinary enzyme indices, and haemostatic function tests [buccal mucosa bleeding time (BMBT), cuticle bleeding time (CBT)]. Significant changes were observed in the KP group, including a decrease of ERPF and GFR, an increased UAlb/Cre ratio, prolonged BMBT and CBT, as well as the presence of more severe grades of endoscopic lesions and fecal occult blood. In both the MP and KP groups, abnormal enzymuria with exfoliation of renal tubular epithelial cells in the urine was found. However, no significant changes in any of the other tests were observed in the MP group compared with the NC group. These findings suggest that the combination of NSAIDs, even selective COX-2 inhibitors, with prednisolone may be contraindicated due to the potential for serious adverse effects on the kidneys, the platelets, and the gastrointestinal tract.     

Antioxidative activity of green tea treated with radical initiator 2, 2'-azobis(2-amidinopropane) dihydrochloride

This study investigated the antioxidative activity of green tea extract, and a green tea tannin mixture and its components, under conditions of radical generation using the hydrophilic azo compound, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to generate peroxyl radicals at a constant and measurable rate in the cultured renal epithelial cell line, LLC-PK(1), which is susceptible to oxidative damage. Treatment with AAPH decreased cell viability and increased the formation of thiobarbituric acid-reactive substances. However, green tea extract, and the tannin mixture and its components, comprising (-)-epigallocatechin 3-O-gallate (EGCg), (-)-gallocatechin 3-O-gallate (GCg), (-)-epicatechin 3-O-gallate (ECg), (-)-epigallocatechin (EGC), (+)-gallocatechin (GC), (-)-epicatechin (EC), and (+)-catechin (C), showed protective activity against AAPH-induced cellular damage. The tannin mixture and its components exhibited higher antioxidative activity than the green tea extract. Furthermore, EGCg and GCg had higher activity than EGC and GC, respectively. In particular, EGCg exerted the most significant cellular protective activity against AAPH. These results indicate that green tea tannin may inhibit cellular loss and lipid peroxidation resulting from the peroxyl radical generated by AAPH, and that the chemical structure of tannin is also involved in the activity, suggesting that the O-dihydroxy structure in the B ring and the galloyl groups are important determinants for radical scavenging and antioxidative potential.     

Phylogenetic Analysis of Soybean-Nodulating Rhizobia Isolated from Alkaline Soils in Vietnam

In order to analyze the phylogeny of soybean-nodulating bacteria in alkaline soils in Vietnam, indigenous soybean-nodulating bacteria were isolated from root nodules by cultivating three kinds of Rj -soybean cultivars on two alkaline soils in Vietnam. The 120 isolates were classified into two major genera of soybean-nodulating rhizobia, namely Bradyrhizobium and Sinorhizobium genera, based on a growth analysis on medium and PCR-RFLP analyses of 16S rDNA and of the 16S–23S rDNA internal transcribed spacer (ITS) region. Most of the isolates of B. japonicum were extra-slow-growing and their ITS types were similar to that of B. japonicum USDA 135. They were not isolated from the soybean cultivar CNS used as Rj₂Rj₃ genotype. Isolates of Sinorhizobium were divided into two groups, S. fredii and S. sp., based on a PCR-RFLP analysis of 16S rDNA. Furthermore, PCR-RFLP analysis of the 16S–23S rDNA ITS region enabled to separate them into five types, three ITS types associated with S. fredii and two with S. sp. Sinorhizobium was frequently isolated from the three soybean cultivars on two soils. From the isolate ratio, it was suggested that B. japonicum strains similar to B. japonicum USDA 135 and S. fredii predominated in the alkaline soils of Vietnam. Additionally, our findings indicated that the Rj -genotypes affected not only the compatibility, but also the preference for nodulation between the host soybean and rhizobia.     

Some Measurement Results on Sulfate Aerosol Concentration in and above a Pine Canopy

Profile of sulfate aerosol (SO₄ ^2?) concentration was measured for four days at six heights in and above a 15m-high canopy of pine plantation during 6th and 10th August. 1999. The concentration was the lowest (about 2 nmol/m³) on 6th, and gradually increased to 9th showing the maximum values of about 13 nmol/m³, and then decreased to 2 nmol/m³ on 10th. The vertical profiles of SO₄ ^2? concentration showed mostly higher in the canopy than above the canopy. As for the vertical profiles above the canopy on 8th and 10th, the minimum was observed just above the canopy (16m), showing SO₄ ^2? transport from the upper air layer to the canopy. While on 9th the profiles that are higher concentration just above the canopy and lower at the upper air layer were observed, suggesting SO₄ ^2? emission from the canopy to the upper air layer.