Study on the Basic Mechanical Behaviors of High Density Polyethylene Electrofusion Welded Joints at Different Temperature

The basic mechanical behaviors of high density polyethylene electrofusion welded joint at different temperatures were studied by using differently designed specimens in this paper. The results show that the strength of weld bonding plane is higher than that of the pipe and socket materials at room temperature. In order to get the shear strength of electrofusion welded joint, the effective bond lengths were reduced by cutting artificial groove through the socket. The effective bonding length of welded joint to get the shear strength is decreased with decreasing testing temperature. The shear strength and the sensibility to sharp notch of HDPE material increased with decreasing temperature.

Mechanical Nature of Gravity and Tectonic Forces

There are two models of ultrahigh pressure metamorphism (UHPM) zone in Dabie: the model of under thrusting returning which even arrives at the mantle and the superimposed model of tectonics in the crust. There are two points of view in the argument about formation depth of ultrahigh pressure metamorphism: (1) the depth can be calculated by hydrostatic equation; (2) the high pressure was composed of gravity, tectonic and other forces instead of merely gravity force. Some misunderstandings of mechanical conceptions presented in the paper showing the hydrostatic viewpoints should be open to question. The main conceptions are: (1) the confining pressure was only formed by gravity, and the differential stress was only formed by tectonic force; (2) the differential stress is not big enough to lead to form ultrahigh pressure metamorphism; (3) once tectonic overpressure goes beyond the limited strength of rocks the tectonic force would disappear and the rocks would be broken or rheomorphied at the same time. A short discussion in basic mechanics is made in this paper for a perfect process for discussing the argument.

Progress on pollen-stigma compatibility in Corylus (hazelnuts): a review

The genus Corylus is an important member in the Betulaceae family of the order Fagales. Self-incompatibility is one of the choke points in breeding and hazelnut production. This reviewe describes, the progress on pollen-stigma compatibility in Corylus, including basic re- productive characteristics, S-alleles testing and their applications, in- ter-specific hybridization, self-compatibility in wild species, and recent molecular research on the genetic mechanism of compatibility. Com- pared with other species, progress on pollen-stigma compatibility （sporophytic self-incompatibility, SSI） in Corylus is slow, especially those in the Brassicaceae family. De novo approaches should be used to target the unique reproductive characteristics of hazelnuts. The continu- ous improvement of technological platforms based on molecular biology should broaden the pathways in investigating compatibility in Corylus. In addition, research should be conducted on overcoming self- and cross- incompatibility, and approaches based on biological, chemical, and physical principles should be introduced. Both theoretical and practical study of compatibility in Corylus should be devoted to change the self-incompatibility trait into a benefit in the species evolvement and nut quality establishment.

One-step synthesis of basic magnesium sulfate whiskers by atmospheric pressure reflux

We have developed a one-step process for the synthesis of basic magnesium sulfate （5Mg（OH）2-MgSO4-3H20, abbreviated as 513MOS） whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process shows potential for the low-cost mass production of controlled- structure whiskers. Their 0.3-1.0 μm diameter and 40-80 μm length correspond to an aspect ratio of 40-260. The 513MOS whisker morphology is related closely to MgSO4 concentration and reflux time. The optimized MgSO4 concentration is 1.2-1.5 mol/L with a 25-30 h reflux time. X-ray diffractometry revealed that the b-axis is the predominant growth direction of the whiskers. Their growth mechanism is by the relatively slow liquid-phase deposition of Mg2＋, OH-, and SO42-. The long reaction time and high MgSO4 concentration are conducive to the formation of 513MOS whiskers under gentle reaction conditions. Porous MgO whiskers with a fibrous structure were obtained after calcination of the 513MOS whiskers at 1020 ℃.