In 1916, G. N. Lewis introduced the electron pair bond.

In chemistry, an electron pair or a Lewis pair consists of two electrons that occupy the same orbital but have opposite spins.

He proposed that two atoms may share from one to six electrons forming single, double or triple bonds.

He introduced the cubical atom and six postulates to understand their chemical behaviour.

That chemical bond decides the properties of molecules such as colour, reactivity, solubility, etc. all of which decide their applications.

The Bio-Indicator Lidar Instrument, or BILI is a fluorescence-based lidar, a type of remote-sensing instrument similar to radar in principle and operation.

Instead of using radio waves, however, lidar instruments use light to detect and ultimately analyze the composition of particles in the atmosphere.

Scientists have discovered ULAS J1342+0928, the oldest supermassive black hole ever found - a behemoth that grew to 800 million times the mass of the sun when the universe was just 5 percent of its current age.
This newfound giant black hole, which formed just 690 million years after the Big Bang, could one day help shed light on a number of cosmic mysteries, such as how black holes could have reached gargantuan sizes quickly after the Big Bang and how the universe got cleared of the murky fog that once filled the entire cosmos.
Supermassive black holes with masses millions to billions of times that of the sun are thought to lurk at the hearts of most, if not all, galaxies.
Previous research suggested these giants release extraordinarily large amounts of light when they rip apart stars and devour matter, and likely are the driving force behind quasars, which are among the brightest objects in the universe. Astronomers can detect quasars from the farthest corners of the cosmos, making quasars among the most distant objects known. The farthest quasars are also the earliest known quasars - the more distant one is, the more time its light took to reach Earth. The previous record for the earliest, most distant quasar was set by ULAS J1120+0641. That quasar is located 13.04 billion light-years from Earth and existed about 750 million years after the Big Bang. The newfound quasar (and its black hole), named ULAS J1342+0928, is 13.1 billion light-years away.

Researchers at the Indian Institute of Technology (IIT) Bombay have successfully made low-cost piezo-resistive vibration sensors using polyurethane foam coated with carbon nanomaterial-based ink.
These sensors can be used for monitoring the health of industrial machines and equipment and help identify incipient failures thereby enabling efficient maintenance schedule planning.
The ink is made of functionalised multi-walled nanotubes that are dispersed in a reduced graphene oxide matrix.
It is conductive due to the presence of large number of multiwalled nanotubes.
The ink, which uniformly coats the pores of the foam when dipped-coated, imparts piezo-resistive properties.
Conductive sheets (made of indium titanium oxide coated polyethylene teraphalate) were pasted on the top and bottom sides of the foam and electrical wires connected to the sheets for measurements.
The ink and sensor were developed at the Plastic Electronics and Energy Laboratory (PEEL), Department of Metallurgical Engineering and Material Science, IIT Bombay.
How It Works
When the PU foam coated with the ink is perturbed, in this case compressed, the air gaps are removed and the foam gets thinner.
This provides a conduction path for electrical charges. The resistance drops as the foam is compressed and it becomes more conductive.
The sensor is so sensitive that it can measure blood pulse. The total cost of materials required for making the sensors works out to less than Rs.200 per sensor, and can be reduced further if mass produced.
The ink costs only about Rs.7 per sensor. No sophisticated equipment is required for fabricating the sensor.
The sensing bandwidth of the sensor is 80 Hz and the team was able to classify different machine operating conditions (good versus bad bearing, and good versus bad gearbox) based on vibration signals.
To be able to identify the danger signs of a machine, the output of the vibration sensor has to be captured and the Fast Fourier Transform (FFT) has to be computed. One should then look where the peaks are located in the FFT.