Influence of the Temperature of a Body on Its Weight

The physical preconditions are considered for the temperature of a body to influence the force of gravity experienced by it. The results are given of experiments on weighing metal rods heated by ultrasound which confirm a dependence of the weight of the rods on their temperature.     

Influence of orientation of bar on its mass

The influence of vertical gradients of gravity, air density and temperature, magnetic induction, as well as air convection on the measured mass of an extended specimen is theoretically estimated. An experiment designed to compare the mass of a vertically oriented nonmagnetic titanium bar to the same bar when oriented in the horizontal plane is described. Possible factors responsible for the discrepancy between the experimental results obtained and the theoretical estimates presented are discussed. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 22–24, May, 1998.     

Improving the Accuracy of Comparisons of Standard Weights of Different Volumes with a Change in the Density of the Surrounding Air during Measurement

This article describes a method that makes it possible to significantly improve accuracy in the comparison of standard weights of different volumes (made of different materials) by changing the density of the surrounding air during measurements.     

Macroscopic Fluctuations in the Density of Water

Measurements have been made on the density of distilled water over several years in two separate laboratories, which leads to a discussion of macroscopic fluctuations in the density of water.     

Localized states in the active region of blue LEDs related to a system of extended defects

Blue light-emitting diodes (LEDs) based on InGaN/GaN quantum wells (QWs) with different characters of the system of extended defects (SEDs) threading through the active region have been studied using the current-voltage (I–U), capacitance-voltage (C–V), and deep-level transient spectroscopy (DLTS) measurements in the dark and under illumination with white light in a temperature range from 100 to 450 K. The DLTS curves exhibit broad E1 and E2 peaks with amplitudes dependent on the illumination. This behavior can be explained assuming the presence of localized states related to SEDs in the active region of the LED. The LEDs with more developed SEDs are characterized by a greater concentration of donor-type traps, which leads to an increase in the density of free charge carriers in QWs, which screen the electron-hole interaction. This circumstance can be among the factors responsible for a severalfold decrease in the quantum efficiency of such LEDs.     

A Float-Type Liquid Density and Viscosity Sensor

A primary transducer is described for the density and viscosity of a liquid, which employs a ferromagnetic float and oscillates vertically in response to an alternating magnetic force. The viscosity and density are determined from the times taken for the float to rise and fall a set distance.