In astronomy, methods such as direct imaging or interferometry-based techniques (Michelson stellar interferometry for example) are used for observations. A particular advantage of interferometry is that it permits greater spatial resolution compared to direct imaging with a single telescope, which is limited by diffraction owing to the aperture of…

A simple bioassay was designed for the detection of adenosine, a human metabolite involved in several physiological processes, on the basis of the functionalization of gold nanoparticles with DNA oligonucleotides selectively binding adenosine. The test was possible thanks to the selective and sensitive binding of adenosine by two DNA…

An introductory guide to deducing the mechanism of chemical reactions is presented. Following a typical workflow for probing reaction mechanism, the guide introduces a wide range of kinetic and mechanistic tools. In addition to serving as a broad introduction to mechanistic analysis for students and researchers, the guide has also been used by…

Terms to be familiar with before you start to solve the test: tryptophan, transcription unit, operon, "trp" repressor, corepressor, operator, promoter, palindrome, initiation, elongation, and termination of transcription, open reading frame, coupled transcription/translation, chromosome-polysome complex. (Contains 2 figures and 1 footnote.)

Natural selection and other components of evolutionary theory are known to be particularly challenging concepts for students to understand. To help illustrate these concepts, we developed a simulation model of microevolutionary processes. The model features all the components of Hardy-Weinberg theory, with population size, selection, gene flow,…

This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements.…

We propose a series of experiments involving balance readings of an object naturally floating or forced to be partially or fully immersed in water contained in a beaker sitting on an electronic scale balance. Students were asked to predict, observe and explain each case. The teacher facilitated the learning by asking probing questions, giving…

Two curious thought experiments concerning the speed of light are presented which have been used to provoke the interest of undergraduate physics students. (Contains 2 figures.)

This article describes a novel experiment focused on metal ion hydrolysis and the equilibria related to metal ions in aqueous systems. Using [superscript 27]Al NMR, the students become familiar with NMR spectroscopy as a quantitative analytical tool for the determination of aluminum by preparing a standard calibration curve using standard aluminum…

The null result of the Michelson-Morley experiment and the constancy of the one-way speed of light in the "rest system" are used to formulate a simple problem, to be solved by elementary geometry techniques using a pair of compasses and non-graduated rulers. The solution consists of a drawing allowing a direct visualization of all the fundamental…

To overcome students' inaccurate prior knowledge on primary additive colours, a coloured-light mixer has been constructed to enable students to observe directly the colours produced and reach the conclusion by themselves that the three primary colours of light are red, green, and blue (NOT red, yellow, and blue). Three closely packed tiny…

When it comes to directly interacting with and doing experiments with organisms, plants have some distinct advantages over animals. Their diversity and accessibility allows students to use them in experiments, thus practicing important science inquiry skills. This article describes an investigation that was designed to help students appreciate the…

Physics teachers often like to discuss physics concepts with their students on the basis of simple demonstration experiments. In this article, we discuss an experiment for which one only needs a few coins of the same denomination and a wooden stick: the coins are laid alongside the stick on a horizontal surface, the stick is rotated about one of…

We apply several physical ideas to determine the steady temperature distribution in a medium moving with uniform velocity between two infinite parallel plates. We compute it in the coordinate frame moving with the medium by integration over the "past" to account for the influence of an infinite set of instantaneous point sources of heat in past…

We study the turning point problem of a spherical pendulum. The special cases of the simple pendulum and the conical pendulum are noted. For simple initial conditions the solution to this problem involves the golden ratio, also called the golden section, or the golden number. This number often appears in mathematics where you least expect it. To…