Trichosanates A-G and cucurbitacins W-Y, anticomplement monoterpenoids and cucurbitane-type triterpenoids from the pericarps of Trichosanthes kirilowii.

The pericarps of Trichosanthes kirilowii are often used to treat cough in traditional Chinese medicine, and its ethanol extract exhibited effective therapeutic effects on acute lung injury (ALI) in vivo caused by H1N1. An anticomplement activity-guided fractionation on the extract resulted in the isolation of ten new terpenoids, including seven monoterpenoids, trichosanates A-G (1-7), and three cucurbitane-type triterpenoids, cucurbitacins W-Y (8-10), as well as eleven known terpenoids (11-21). The new terpenoids' structures were determined by spectroscopic analysis, X-ray crystallographic analysis (1), electronic circular dichroism (ECD) analysis and calculations (2-10). Twelve monoterpenoids (1-7 and 11-15) and five cucurbitane-type triterpenoids (8-10, 18, and 20) exhibited anticomplement activity in vitro. For the monoterpenoids, the long aliphatic chain substituents might enhance their anticomplement activity. Additionally, two representative anticomplement terpenoids, 8 and 11, obviously attenuated H1N1-induced ALI in vivo by inhibiting complement overactivation and reducing inflammatory responses.

Improved Accuracy for Trace Element Analysis of Al and Ti in Quartz by Electron Probe Microanalysis.

The trace elements in quartz, Al and Ti, contain considerable information about mineral genesis, and determining their concentrations is of great importance in geology. Electron probe microanalysis has the advantages of non-destructive testing and high spatial resolution; however, it is a challenge to improve the accuracy and precision of trace element detection using this method. The important factors affecting accuracy include the fragility of quartz lattices at high beam currents and the methods used to determine the background. In this paper, the peaks of Al-Kα and Ti-Kα, and their backgrounds, were found to exhibit intensity variations at high beam currents and small beam diameters; therefore, it is necessary to select a large beam diameter (up to 20 µm) to avoid variations in intensity at high currents (500 nA). For background determination of Al, a multipoint background method is proposed to determine the background value, which greatly improves the accuracy of the results. For Ti, the choice of background measurement does not affect the result. In addition, it is verified that the background obtained from other quartz samples can be used as the background of an unknown quartz sample, which reduces the analysis time and minimizes sample damage.

A Mathematical Model for Determining Carbon Coating Thickness and Its Application in Electron Probe Microanalysis.

In electron probe microanalysis where materials are coated with a thin conductive carbon coat before analysis, the X-ray intensity detected from a specimen may be affected to various degrees by the thickness of the carbon coating. Differences in the carbon film thickness between specimens and standards may lead to errors in analytical results, particular for lower energy X-rays. In this study, we demonstrate that the location and the distance of the specimen relative to the carbon tip in the coating chamber can affect the thickness of the carbon film produced on the specimen surface during carbon coating. The closer the specimen is to the carbon tip contacting point, the thicker is the carbon film deposited. A mathematical model to calculate the carbon film thickness at different locations on the coater plate is established, based on the assumption that carbon atoms evaporate from the carbon tip equally in all directions during the coating process. In order to reduce the differences in the carbon coating thickness, we suggest moving the carbon rod to a higher position, moving the thinner samples to the center and thicker samples to the edge of the coater plate, and using a rotating circular coater plate during coating.

Influence of microstructural features on thermal expansion coefficient in graphene/epoxy composites.

In this paper, theoretical calculations were conducted to determine the coefficient of thermal expansion (CTE) based on the effective medium approach using Green's function method. The influences of microstructural features were investigated, including volume fraction, aspect ratio, and the orientation of graphene fillers. Calculated results demonstrated strong anisotropy of CTE when all graphene sheets in the composite were aligned in the in-plane direction due to the large difference between the elastic moduli of the graphene and epoxy. The in-plane CTE in the graphene/epoxy composite can be effectively reduced with small additions of graphene additive. Orientation dispersion among the graphene fillers significantly decreases the anisotropy of CTE. Accounting for the influences of all microstructural features, simulation results closely align with current experimental results. This work will provide a general guideline and a solid foundation for the optimal design and preparation of graphene/polymer composites.