When hot water freezes faster

A team of researchers from Spain have defined a theoretical framework that could explain the Mpemba effect, a counterintuitive physical phenomenon revealed when hot water freezes faster than cold water. The researchers, who have recently published the findings in Physical Review Letters, have confirmed how this phenomenon occurs in granular fluids, that is, those composed of particles that are very small and interact among those that lose part of their kinetic energy.

Thanks to this theoretical characterisation, "we can simulate on a computer and make analytical calculations to know how and when the Mpemba effect will occur," said Antonio Lasanta, one of the researchers. "In fact," he said, "we find not only that the hottest can cool faster but also the opposite effect: the coldest can heat faster, which would be called the inverse Mpemba effect." A better understanding of effect won't just advance our understanding of basic science but could also lead to practical applications in future.


Thin devices

Qubits are the key building blocks that lie at the heart of every quantum computer. In order to perform a computation, signals need to be directed to and from qubits. At the same time, these qubits are extremely sensitive to interference from their environment, and need to be shielded from unwanted signals, particularly magnetic fields. It is thus a serious problem that the devices built to shield qubits from unwanted signals are themselves producing magnetic fields. Moreover, they are several centimetres in size. Now, scientists have decreased the size of nonreciprocal devices by two orders of magnitude. Their device is only about a tenth of a millimetre in size, and it is not magnetic. Their study was published in the journal Nature Communications.


For an effective catalyst

Humans have used nanoparticles for many centuries for a variety of purposes like decoration. Today, nanoparticles play an important role in many areas. Metal nanoparticles like gold have been used as catalysts in chemical reactions. Palladium is one such material commonly used to make metal nanoparticles. Palladium Nanoparticles (Pd NPs) are increasingly being used as a catalyst in many reactions.

In a new study, scientists from Assam and Portugal, with assistance from the Department of Biotechnology, India, have developed a new method of synthesising Pd NPs. Using leaf extracts and starch, the scientists were able to synthesise Pd NPs. The scientists collected the leaves of Garcinia pedunculata from Assam. The leaves are turned into a solution which served as a bio-reductant, while starch served as a bio-stabiliser.

Once synthesised, the solution was viewed under spectrophotometer and a transmission electron microscope to verify the presence of the Pd NPs. The scientists then performed three chemical reactions using the Pd NPs as a catalyst. The Pd NPs were proven to be an effective catalyst in all of the reactions. The new method can be seen as a 'green way' to synthesise Pd NPs.


Solar efficiency

Researchers from Karlsruhe Institute of Technology (KIT), Germany have successfully reproduced nanostructures found on the wings of the butterfly, Pachliopta aristolochiae, in solar cells to enhance their light absorption rate by up to 200%. Its wings are drilled by nanostructures that help absorbing light over a wide spectrum far better than smooth surfaces.

The scientists report their results in the journal Science Advances. "The butterfly studied by us is very dark black. This signifies that it perfectly absorbs sunlight for optimum heat management. The optimisation potential when transferring these structures to photovoltaics systems was found to be much higher than expected," says Dr Hendrik Hlscher of KIT's Institute of Microstructure Technology.


Before the Big Bang

If the big bang marked the beginning of our universe, then what existed before it? Before the Big Bang, a four-part documentary series, explores various theories which seek to explain this intriguing mystery. We know that hundreds of billions of galaxies exist in our universe, but what are the odds that other universes existed previous to our own? Top cosmologists, astronomers and scientists are working feverishly on developing these answers. Together, their individual breakthroughs represent crucial incremental steps in the search for expanding knowledge of our universe. With compelling interviews and 3D animations, Before the Big Bang simplifies a series of complex scientific theories for everyone to understand. To watch the documentary, visit

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