The Effect and Mechanism of Lipoxin A4 on Neutrophil Function in LPS-Induced Lung Injury.

Excessive inflammatory response caused by infiltration of a large number of neutrophils is one of the important features of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Lipoxin A4 (LXA4) is an important endogenous mediator in the process of inflammation resolution, which has a strong role in promoting inflammation resolution. In this study, we examined the impact of LXA4 on the pulmonary inflammatory response and the neutrophil function in ARDS rats. Our results indicated that exogenous administration of LXA4 could reduce the degree of lung injury in ARDS rats and inhibit the release of pro-inflammatory factors TNF-α and IL-1ß in lung tissue homogenate. However, LXA4 has no lung protective effect on ARDS rats of neutropenia, nor can it inhibit the levels of pro-inflammatory factors TNF-α and IL-1ß in lung tissue homogenate. LXA4 can inhibit the production of reactive oxygen species (ROS) and neutrophil extracellular traps (NETs) in peripheral blood neutrophils of ARDS rats. At the same time, LXA4 can promote the phagocytosis of neutrophils in ARDS rats in vitro and can also promote the apoptosis of neutrophils in ARDS rats. In addition, the effect of LXA4 on the function of neutrophils in ARDS rats is mediated by its receptor ALX. LXA4 can inhibit the release of NE and MPO from neutrophils, thereby reducing the production of NETs. In summary, these findings indicate that LXA4 has a protective effect on LPS-induced ARDS rats by affecting the function of neutrophils.

Exact Solutions for Torsion and Warping of Axial-Loaded Beam-Columns Based on Matrix Stiffness Method.

The typically-used element torsional stiffness GJ/L (where G is the shear modulus, J the St. Venant torsion constant, and L the element length) may severely underestimate the torsional stiffness of thin-walled nanostructural members, due to neglecting element warping deformations. In order to investigate the exact element torsional stiffness considering warping deformations, this paper presents a matrix stiffness method for the torsion and warping analysis of beam-columns. The equilibrium analysis of an axial-loaded torsion member is conducted, and the torsion-warping problem is solved based on a general solution of the established governing differential equation for the angle of twist. A dimensionless factor is defined to consider the effect of axial force and St. Venant torsion. The exact element stiffness matrix governing the relationship between the element-end torsion/warping deformations (angle and rate of twist) and the corresponding stress resultants (torque and bimoment) is derived based on a matrix formulation. Based on the matrix stiffness method, the exact element torsional stiffness considering the interaction of torsion and warping is derived for three typical element-end warping conditions. Then, the exact element second-order stiffness matrix of three-dimensional beam-columns is further assembled. Some classical torsion-warping problems are analyzed to demonstrate the established matrix stiffness method.

Damage Detection of Asphalt Concrete Using Piezo-Ultrasonic Wave Technology.

Asphalt concrete has been widely used in road engineering as a surface material. Meanwhile, ultrasonic testing technology has also been developed rapidly. Aiming to evaluate the feasibility of the ultrasonic wave method, the present work reports a laboratory investigation on damage detection of asphalt concrete using piezo-ultrasonic wave technology. The gradation of AC-13 was selected and prepared based on the Marshall's design. The ultrasonic wave velocities of samples were tested with different environmental conditions firstly. After that, the samples were destroyed into two types, one was drilled and the other was grooved. And the ultrasonic wave velocities of pretreated samples were tested again. Furthermore, the relationship between velocity and damaged process was evaluated based on three point bending test. The test results indicated that piezoelectric ultrasonic wave is a promising technology for damage detection of asphalt concrete with considerable benefits. The ultrasonic velocity decreases with the voidage increases. In a saturated water environment, the measured velocity of ultrasonic wave increased. In a dry environment (50 °C), the velocity the ultrasonic waves increased too. After two freeze-thaw cycles, the voidage increased and the ultrasonic velocity decreased gradually. After factitious damage, the wave must travel through or most likely around the damage, the ultrasonic velocity decreased. During the process of three point bending test, the ultrasonic velocity increased firstly and then decreased slowly until it entered into a steady phase. At last the velocity of ultrasonic wave decreased rapidly. In addition, the errors of the results under different test conditions need to be further studied.

Investigation of Ageing in Bitumen Using Fluorescence Spectrum.

Bitumen ageing is a very complex process and poses a threat to the performance of pavements. In the present work, a fluorescence spectrophotometer was employed to research the change rule of components and the structure of bitumen after the ageing process. The Thin Film Oven Test (TFOT) and Ultraviolet (UV) light treatment were carried out as ageing methods. The properties and components of bitumen were tested before and after aging. The 2D and 3D fluorescence spectra of bitumen were analyzed. The vector of fluorescence peak was calculated for evaluating the ageing process. The results indicated that the ideal concentration of bitumen- tetrachloromethane solution was 0.1 g/L or smaller for avoiding the fluorescence quenching. The coordinates of fluorescent peak appeared "blue-shift" after ageing due to the change of aromatics. In addition, bitumen has already occurred serious ageing when the magnitude of a vector is more than 36.

Two new steroidal glycosides from Cynanchum wallichii.

Two new C21 steroidal glycosides were isolated from Cynanchum wallichii Wight. Their structures were elucidated as caudatin-3-O-ß-d-glucopyranosyl-(1 → 4)-ß-d-oleandropyranosyl-(1 → 4)-ß-d-cymaropyranosyl-(1 → 4)-ß-d-digitoxopyranoside (1) and caudatin-3-O-ß-d-glucopyranosyl-(1 → 4)-ß-d-cymaropyranosyl-(1 → 4)-ß-d-oleandropyranosyl-(1 → 4)-ß-d-cymaropyranosyl-(1 → 4)-ß-d-digitoxopyranoside (2) by spectroscopic methods including 1D and 2D NMR experiments.