Study on Fatigue Cracking of Diaphragm's Arc Opening of OSD in Steel Bridges by Using Biaxial Stress Method.

Changes in loading position have a significant impact on the stress field of each vulnerable area of an orthotropic steel deck (OSD). The arc opening area of the diaphragm and the connecting area between the U-rib and the diaphragm under the moving load are prone to fatigue cracking. By comparing the stress responses under different methods, the hot spot stress (HSS) method is used as the main stress extraction method in fatigue performance evaluation. The control stress of fatigue cracking was analyzed by comparing the direction of the principal stress field with the crack direction in this experiment. According to the stress amplitude deviation under the biaxial stress state, a set of methods for evaluating the effects of in-plane biaxial fatigue was developed. An improved luffing fatigue assessment S-N curve was applied to analyze the fatigue life of the diaphragm's arc opening area. The results show that when the moving load is exactly above the connection of the deck and the web of the U-rib on one side, it is in the most unfavorable position in the transverse direction, and the diaphragm is mainly under the in-plane stress state. The longitudinal range of the stress influence line of the arc opening is approximately twice the diaphragm spacing. Two to three stress cycles are caused by one fatigue load. Fatigue crack control stress is the principal stress tangential to the arc opening's edge in this area. The normal direction of the principal stress in the model test is roughly consistent with the crack initiation direction. The variation in the stress amplitude deviation in this area is caused by changes in the action position of the moving load. When the moving load is at a certain distance from the involved diaphragm, it is reduced to zero, implying that the in-plane fatigue effect is the greatest in this area.

Isolation, X-ray crystal structure of the new diterpene and identification of others lignans and flavonoids from the fresh needles of Pinus massoniana.

Three new compounds, namely massonside C (1), massonianoside F (2), and 3, 8-dimethyl- herbacetin-7-O-ß-D-glucopyranoside (3), together with five known compounds (4-8), were isolated from the fresh needles of Pinus massoniana. Their structures were established by 1D, 2D NMR, HRMS and comparison with the literature data. The absolute configuration of 1 was confirmed by a combination of X-ray single crystal analysis. All isolated compounds were evaluated for the protective effect of human umbilical vein endothelial cells against oxidative damage.

Isolariciresinol-9'-O-α-L-arabinofuranoside protects against hydrogen peroxide­induced apoptosis of human umbilical vein endothelial cells via a PI3K/Akt/Bad­dependent pathway.

Isolariciresinol-9'-O-α-L-arabinofuranoside (MWS­19) isolated from Pinus massoniana Lamb. Fresh pine needles is the major ingredient of the Songling Xuemaikang capsule therapy used for hypertension. The present study aimed to investigate the effects and underlying mechanisms of MWS­19 on hydrogen peroxide (H2O2)­induced apoptosis in human umbilical vein endothelial cells (HUVECs). To investigate the effect of MWS­19 on apoptosis in HUVECs, an oxidative stress­induced apoptosis model was established in HUVECs using H2O2, and the present study performed Hoechst 33258 staining and a Cell Counting Kit­8 (CCK­8) assay. Furthermore, western blot analysis was also performed to investigate the underlying mechanism of the effects of MWS­19 on the model. The results demonstrated that MWS­19 reversed the effects of H2O2 on cell apoptosis at a concentration range of 15.6­250 µg/ml, with dose­dependent increases in cell growth. Hoechst staining indicated that 500 µM H2O2 induced HUVEC apoptosis, and MWS­19 markedly protected HUVECs against apoptosis at 31.3, 62.5 and 125 µg/ml. Furthermore, the protein expression of phosphatidylinositol 3­kinase (PI3K), phosphorylated­Akt and Bcl­2­associated agonist of cell death (Bad) were increased, and reduced caspase­3 activation was observed, following treatment with MWS­19 in H2O2­treated HUVECs. Additionally, the PI3K inhibitor wortmannin attenuated PI3K/Akt/Bad signaling induced by MWS­19 treatment and neutralized the effect of MWS­19 on the growth of HUVECs. In conclusion, the results of the present study indicate that MWS­19 may protect against H2O2­induced HUVEC apoptosis via the PI3K/Akt/Bad signaling pathway. MWS­19 may serve an important role in the prevention of oxidative damage in vascular endothelial cells in hypertension patients.

Two new sesquiterpene glycosides isolated from the fresh needles of Pinus massoniana Lamb.

Two new sesquiterpene glycosides, namely massonside A (1) and massonside B (2), were isolated from the n-Bu extract of the fresh needles of Pinus massoniana Lamb. Their structures were established by 1D, 2D nuclear magnetic resonance and high-resolution mass spectrometry. Their biological activities were profiled by the anti-HBV and anti-HCV assays.

The Effects of Puerarin on Rat Ventricular Myocytes and the Potential Mechanism.

Puerarin, a known isoflavone, is commonly found as a Chinese herb medicine. It is widely used in China to treat cardiac diseases such as angina, cardiac infarction and arrhythmia. However, its cardioprotective mechanism remains unclear. In this study, puerarin significantly prolonged ventricular action potential duration (APD) with a dosage dependent manner in the micromolar range on isolated rat ventricular myocytes. However, submicromolar puerarin had no effect on resting membrane potential (RMP), action potential amplitude (APA) and maximal velocity of depolarization (Vmax) of action potential. Only above the concentration of 10 mM, puerarin exhibited more aggressive effect on action potential, and shifted RMP to the positive direction. Millimolar concentrations of puerarin significantly inhibited inward rectified K+ channels in a dosage dependent manner, and exhibited bigger effects upon Kir2.1 vs Kir2.3 in transfected HEK293 cells. As low as micromolar range concentrations of puerarin significantly inhibited Kv7.1 and IKs. These inhibitory effects may due to the direct inhibition of puerarin upon channels not via the PKA-dependent pathway. These results provided direct preclinical evidence that puerarin prolonged APD via its inhibitory effect upon Kv7.1 and IKs, contributing to a better understanding the mechanism of puerarin cardioprotection in the treatment of cardiovascular diseases.

[Study on flavonoid chemical constituents contained in Memorialis hirta].

OBJECTIVE: To study the chemical constituents of Memorialis hirta. METHOD: Compounds were isolated and purified by multiple methods, and their structures were identified based on physicochemical property and spectrum data. RESULT: 12 compounds were isolated from ethyl acetate from 95% ethanol extracts of M. hirta, they were isorhamnetin (1), kaempferol (2), quercetin (3), isorhamnetin-3-O-alpha-L-rhamnopyranoside (4), kaempferol-3-O-alpha-L-rhamnopyranoside (5), isorhamnetin-3-O-beta-D-glucopyranoside (6), kaempferol-3-O-beta-D-glucopyranoside (7), quercetin-3-O-alpha-L-rhamnopyranoside (8), quercetin-3-O-beta-D-glucopyranoside (9), isorhamnetin-3-O-rutinoside (10), kaempferol-3-O-rutinoside (11) and quercetin-3-O-rutinoside (12), respectively. CONCLUSION: All compounds were obtained from the genus Memorialis for the first time.

[Flavonoid glycosides from Androsace umbellata].

OBJECTIVE: To study the chemical constituents of Androsace umbellata. METHOD: Many chromatography means were used in separation and purification, and the structures of all compounds were identified by the means of spectroscopic analysis and physico-chemical properties. RESULT: 10 compounds were elucidated as kaempferol 3-O-(3-O-acetyl-)-alpha-L-rhamnopyranoside(1), kaempferol 3-O-(2-O-acetyl-)-alpha-L-rhamnopyranoside(2), kaempferol 7-O-alpha-L-rhamnopyranoside(3), kaempferol 3-O-alpha-L- rhamnopyranoside(4), kaempferol 3-O-beta-D-glucopyranoside(5), kaempferol 3-O-(3-O-acetyl-)-a-L-rhamnopyranosyl-7-O-alpha-L- rhamnopyranoside(6), kaempferml 3-O-(4-O-acetyl-)-alpha-L-rhamnopyranosyl-7-O-alpha-L-rhamnopyranoside(7), quercetin 3-O-alpha-L- rhamnopyranoside(8), quercetin 3-O-beta-D-glucopyranoside(9) and myricetin 3-O-beta-D-glucopyranoside (10), respectively. CONCLUSION: All compounds were obtained from the title plant for the first time.