Established in 1933 by the Nobel Laureate C.V. Raman, the Department of Physics soon evolved into the leading centre in the country for advanced postgraduate education and cutting-edge research in physics. The largest number of Ph.D.s in physics in India -- 110 since 1998 -- come from this department. Graduates from the department have gone on to distinguished careers in science and occupy leading positions in research institutes in India and the world over. ...more
A Micrometer-sized Engine Operating Between Bacterial Reservoirs
Be it in the first automobile ever manufactured - the Ford Model T - or a contemporary family sedan, the basic working principle of the
heat engine has remained unchanged since it was first laid down by French Engineer Sadi Carnot in 1824. Heat from the exploding fuel-air
mixture inside the engine is partly converted to work âhe motion of the piston - and the rest is thrown out as waste heat to the outside
colder environment. An essential prerequisite for such an engine to perform work is that in needs to operate between two thermal
reservoirs a hot and a cold one. Unlike these familiar large engines, nanometer-sized molecular engines inside the human body, essential
for transporting cargo within the cell and for moving our limbs, work at nearly 100% efficiency at a fixed temperature - the normal body
temperature of 37.5°C stays put as we use our fingers to scroll through this write up. The functioning of these amazing machines has
intrigued scientists for decades.
In a recent research breakthrough, a team of scientists from the Indian Institute of Science and the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore suggest a potential physical mechanism that can enhance our understanding of how these molecular machines function. In a series of careful and high precision experiments, the Bangalore team studied the dynamics of an optically trapped colloidal particle, only 1/50th the thickness of the human hair, in a soup of motile bacteria. The bacterial mobility could be turned âând âFây very small changes in temperature. As opposed to large engines, micro and nanometer-sized engines are strongly perturbed by fluctuations in their environments. Thus, even while the temperature of the reservoirs was nearly constant, changes in the nature of fluctuations of the colloidal particle in the ON and OFF states of bacterial activity allowed these researchers to estimate the work done by the colloidal bead. Remarkably, this tiny artificial engine outperformed conventional engines in efficiency. These results were reported in the journal Nature Physics (DOI: 10.1038/nphys3870)
Suddesh Krishnamurthy, Subho Ghosh, Dipankar Chatterji, Rajesh Ganapathy and A K Sood Nature Phys. 2016 (DOI: 10.1038/nphys3870)
Spin injection, manipulation and detection are the integral parts of spintronics devices and have attracted tremendous attention in the last decade.
It is necessary to judiciously choose the right combination of materials to have compatibility with the existing semiconductor technology. Conventional metallic magnets were the first choice for injecting spins into semiconductors in the past.