Study of the influence of different designs of massive rotor of asynchronous generator on their maximum power

The article deals with the experimental results of the short-circuit experience, active and inductive resistances of a massive rotor with short-circuited copper cells. And also experimental mechanical characteristics of model asynchronous generators with different massive rotors at the same overall power have been studied.

Design of a Bulk Conductive Polymer Using Embedded Macroscopic Copper Cells

This paper introduces a technique of inducing bulk conductivity in a polymer. The technique uses coiled copper ‘cells’ embedded into a polymer during fabrication which can subsequently create highly redundant series-parallel networks. The preceding body of work aimed to improve the conductivity of non-conducting polymers by embedding particulates (of metal, carbon, etc.) into the polymer, or by altering the polymerization chemistry to incorporate conductive elements. The technique described here keeps the process independent of the specific polymer chosen by not relying on the polymerization chemistry to aid in the incorporation of the cells. The embedding drastically lowers the resistivity of the polymer, from 1012 Ω -cm (approx.) for pure silicone rubber to less than 50 Ω -cm for the composite at room temperature: a drop of 12 orders of magnitude. A secondary consideration of this paper is the mechanical stiffness changes brought about by the embedding of metal inside a flexible polymer. Although the connected network of copper cells allows the rubber to be highly conductive in bulk, the cells are themselves compliant and thus have minimal effect on the stiffness of the cured silicone rubber.

A Family Knockout of All Four Drosophila Metallothioneins Reveals a Central Role in Copper Homeostasis and Detoxification

ABSTRACT Metallothioneins are ubiquitous, small, cysteine-rich proteins with the ability to bind heavy metals. In spite of their biochemical characterization, their in vivo function remains elusive. Here, we report the generation of a metallothionein gene family knockout in Drosophila melanogaster by targeted disruption of all four genes (MtnA to -D). These flies are viable if raised in standard laboratory food. During development, however, they are highly sensitive to copper, cadmium, and (to a lesser extent) zinc load. Metallothionein expression is particularly important for male viability; while copper load during development affects males and females equally, adult males lacking metallothioneins display a severely reduced life span, possibly due to copper-mediated oxidative stress. Using various reporter gene constructs, we find that different metallothioneins are expressed with virtually the same tissue specificity in larvae, notably in the intestinal tract at sites of metal accumulation, including the midgut's “copper cells.” The same expression pattern is observed with a synthetic minipromoter consisting only of four tandem metal response elements. From these and other experiments, we conclude that tissue specificity of metallothionein expression is a consequence, rather than a cause, of metal distribution in the organism. The bright orange luminescence of copper accumulated in copper cells of the midgut is severely reduced in the metallothionein gene family knockout, as well as in mutants of metal-responsive transcription factor 1 (MTF-1), the main regulator of metallothionein expression. This indicates that an in vivo metallothionein-copper complex forms the basis of this luminescence. Strikingly, metallothionein mutants show an increased, MTF-1-dependent induction of metallothionein promoters in response to copper, cadmium, silver, zinc, and mercury. We conclude that free metal, but not metallothionein-bound metal, triggers the activation of MTF-1 and that metallothioneins regulate their own expression by a negative feedback loop.