Structures In Different Stages Research Articles

Direct Observation of Monolayer Zones in Al-wt 4% Cu

Since the early works on GP zones and the model independently proposed by Preston and Guinier on the first steps of precipitation in supersaturated solid solution of aluminium containing a few percent of copper, many works have been performed to understand the structure of different stages in the sequence of precipitation.The scheme which is generally admitted can be drawn from a work by Phillips.In their original model Guinier and Preston analysed a GP zone as composed of a single (100) copperrich plane surrounded by aluminum atomic planes with a slightly shorter distance from the original plane than in the solid solution.From X-ray measurements it has also been shown that GP1 zones were not only copper monolayer zones. They could be up to a few atomic planes thick. Different models were proposed by Guinier, Gerold, Toman. Using synchrotron radiation, proposals have been recently made.

Hydrological Dynamics and the Evolution of Field Form and Use: Resolving the Knapp-smith Controversy

Ongoing gradual uplift of the Pacific watershed of Peru results in water table subsidence. As a mechanical consequence, the form and use of embankment-bound fields evolve through a series of distinct stages. Conflicting interpretations arise as a consequence of different investigators having addressed field structures in different stages of evolution.

Functional and structural relationships in steroidogenesis in vitro by human ovarian follicles during maturation and ovulation.

To investigate steroidogenic function of human follicles in the light of their structures, eight antral follicles of different sizes were mechanically isolated from ovaries of patients laparotomized in the follicular phase of the menstrual cycle with or without pretreatment with human menopausal gonadotropin (hMG). A portion of each follicle was taken for histology and slices of each follicle were incubated with [1-14C]-acetate. Incorporation into progestins, androgens, and estrogens was assessed by the reverse dilution technique with recrystallization to constant specific activity. A predominant incorporation into 17 beta-estradiol was observed in two maturing follicles, whereas a marked increase in incorporation into 17 beta-estradiol with a concomitant decrease in incorporation into androstenedione was verified in two other mature follicles. Remarkable enhancement in relative incorporation into C21 steroids was commonly noted in four preovulatory follicles. However, with the progress of preovulatory stages toward ovulation, as judged from structural changes of the follicles, actual incorporation into C19 and C18 steroids showed a moderate increase, followed by a drastic decrease around the time of ovulation. hMG injection induced similar relationships between the steroidogenic pattern and the follicle structure of different stages, although overall incorporation was considerably increased. We conclude that marked qualitative and quantitative changes in the steroidogenic function and accompanying corresponding changes in structure occurred over the period of follicular maturation and ovulation.

Structure of Spun Yarn and Its Mechanical Non-Linear Property in the Initial Region of Tensile Deformation

This article analyzes the mechanical non-linear property of spun yarn in initial tensile deformation which has an important bearing on the handle of fabrics.The article describes observations and a statistical analysis of spun yarn structures in different stages of tensile deformation.This statistical analysis mathematically expresses spun yarn structure and makes it possible to present an idealized mechanical structure model.