High nitrogen steel (HNS)

High nitrogen steels (HNS) are a new class of high alloy martensitic, austenitic or duplex grades with up to 0.9 mass% of N in solid solution. 

• They are applied e.g. to stainless tools and bearings, in chemical engineering and for high strength non-magnetic components.

Defence Metallurgical Research Laboratory (DMRL), Hyderabad, a premier research laboratory of Defence Research and Development Organization (DRDO) and Jindal Stainless (Hisar) Limited (JSHL) have signed the Licensing Agreement for Transfer of Technology of High Nitrogen Steel (HNS) for armour applications. 

• HNS technology developed by DMRL and DRDO is a step forward towards Army’s quest for lighter and high performance armouring material compared to the currently used materials.

• HNS is not only tough but also has good strength. 
• In addition to being non magnetic as well as corrosion resistant, the HNS cost is about 40 percent less compared to Rolled Homogenous Armour Steel (RHA). 
• Very few countries in the world have developed this technology of HNS. 
• This material has potential for a number of defence and civil applications like armouring, mine trawls, oil industries etc. 

Polar Satellite Launch Vehicle (PSLV) C37 & Cartosat-2

The Indian Space Research Organisation (ISRO) successfully launched a record 104 satellites in one mission from Sriharikota on 15th February, 2017 by relying on its workhorse Polar Satellite Launch Vehicle (PSLV) C37 rocket. 

• An earth observation Cartosat-2 series satellite (Cartosat 2 D) and two other Indian Nano Satellites (INS) were the only Indian satellites launched.
• The remaining were from the United States, Israel, the UAE, the Netherlands, Kazakhstan and Switzerland.
• Of the 101 foreign satellites launched, 96 were from the U.S. and one each from the other five countries.
• Till now Russia held the record of launching 37 satellites in a single mission, in 2014, while the National Aeronautics and Space Administration (NASA) of the U.S. launched 29 satellites in one go in 2013.
• The launch is particularly significant as ISRO now cements its position as a key player in the lucrative commercial space launch market by providing a cheaper yet highly reliable alternative.

Cartosat 2 Series:-

• The Cartosat 2 D satelite launched with the PSLV 37 C on 15 February 2017 is the fifth among the six satelites in the series.
• The previous Cartosat-2 C satellite was the primary satellite carried by PSLV-C34 in July 2016. This satellite is similar to the earlier Cartosat-2, 2A and 2B.
• Cartosat-2 suffered from some problems after launch in the year 2007. An improved Cartosat 2A was launched in 2008. Cartosat 2B followed in 2010.
  • Beginning with Cartosat 2C, a Multi-spectral camera was added and a lower 505 km orbit for better ground resolution was introduced.
  • Cartosat 2C was launched in June 2016.
  • Cartosat 2D has been launched on 15th February 2017 and Cartosat 2E is planned for late 2017.
• Cartosat-2 is an advanced remote sensing satellite with a single panchromatic camera (PAN) capable of providing scene-specific spot images for cartographic applications.
• The camera is designed to provide images with better than one meter spatial resolution and a swath of 10 km.
• The satellite will have high agility with capability to steer along and across the track up to + 45 degrees.
• It is to be placed in a sun-synchronous polar orbit.
• It will have a revisit period of approximately four days. The re-visit can be improved to one day with suitable orbit manoeuvres.
• Several new technologies like two mirror on axis single camera, Carbon Fabric Reinforced Plastic based electro optic structure, lightweight, large size mirrors, JPEG like data compression, advanced solid state recorder, high-torque reaction wheels and high performance star sensors are being employed in Cartosat-2.

• The imagery of Cartosat-2 series satellite will be useful cartographic applications, urban and rural applications, coastal land use and regulation, utility management like road network monitoring, water distribution, creation of land use maps, precision study, change detection to bring out geographical and man made features and various other Land Information System (LIS) and Geographical Information System (GIS) applications. 

Polar Sun Synchronous Orbit:-

• This orbit is a special case of the polar orbit.
• Like a polar orbit, the satellite travels from the north to the south poles as the Earth turns below it.
• In a sun-synchronous orbit, though, the satellite passes over the same part of the Earth at roughly the same local time each day.
• This can make communication and various forms of data collection very convenient.
• Approximate distance of the orbit is from 500 to 600 km.

ISRO nano satellites (INS):- 

• Besides setting the record for the most number of satellites launched in a single mission, the Indian space agency has launched two nano satellites weighing less than 10 kg with the PSLV C37 mission.
• It is a technology demonstrator for a new class of satellites called ISRO nano satellites (INS).
• The main objective of the INS, which will be launched together with bigger satellites, is to provide a platform on which payloads up to 5 kg from universities and R&D laboratories, and ISRO itself can be easily integrated for carrying out scientific research activities.
• With many Indian universities already building and launching nano satellites, the availability of a dedicated nano satellites platform is sure to boost space research in India.

Biofertilizers

Bio-fertilizers are living or biologically active products or microbial inoculants of bacteria, algae and fungi which are able to enrich the soil with nirogen (N), phosphorus (P) and organic matter etc.

Following are some of the important types of bio-fertilizers which can be considered for agro based industries.

• Rhizobium Biofertilizer:- 
• Rhizobium is a symbiotic bacteria forming root nodules in legume plants. 
• The nodules act as miniature nitrogen production factories in the fields. The nodule bacteria fix more nitrogen than  needed for the legume plant and the bacteria.
• The surplus fixed nitrogen is secreted into the field and fertilizes the soil.
• Rhizobium is more efficient than free living nitrogen fixing bacteria and can fix upto 200kg N/ha/year.

• Azotobactor Biofertilizer:-
• Azotobacter are aerobic free living nitrogen fixers. They grow in the rhizosphere (around the roots) and fix the atmospheric nitrogen non-symbiotically and make it available to particular cereals.
• These bacteria produce growth promoting hormones which helps in enhancing growth and yield of the plant.
• These are free living bacteria which grow well on a nitrogen free medium. 
• These bacteria utilize atmospheric nitrogen gas for their cell protein synthesis. This cell protein is then mineralised in soil after the death of Azotobacter cells thereby contributing towards the nitrogen availability of the crop plants.
• Azotobacter spp.,are sensitive to acidic pH, high salts, and temperature above 350C.
• There are four important species of Azotobacter viz. A.Chroococcum, A.agilis, A.paspali and A.vinelandii of which A.chroococcum is most commonly found in our soils.
• The species of Azotobacter are known to fix on an average 10 mg.of N/g of sugar in pure culture on a nitrogen free medium

• Azospirillium Biofertilizer:-
• The are aerobic free living nitrogen fixers which live in associative symbiosis.
• In this type of symbiosis bacteria live on the roots of the host plant and do not form any nodule with the roots.
• It increases crop yield and inoculation benefits crops.
• They also help the host plant by supplying growth hormones and vitamins.
• These bacteria are commonly used for preparation of commercial inoculants.
• Note:-
• Microbial inoculants also known as soil inoculants are agricultural amendments that use beneficial endophytes (microbes) to promote plant health. 
• Many of the microbes involved form symbiotic relationships with the target crops where both parties benefit (mutualism).
• While microbial inoculants are applied to improve plant nutrition, they can also be used to promote plant growth by stimulating plant hormone production
• Blue Green Algae:-
• Blue Green Algae (BGA or cyanobacteria) like Nostoc or Anabaena are free living photosynthetic organisms also capable of fixing the atmospheric nitrogen.
• In the flooded rice fields blue green algae serves as the nitrogen biofertilizer.
• When environmental conditions are just right, blue-green algae can grow very quickly in number. 
• Most species are buoyant and will float to the surface, where they form scum layers or floating mats. When this happens, we call this a "blue-green algae bloom."
• Azolla Biofertilizer:-
• Azolla is a water fern inside which grows the nitrogen fixing blue green algae Anabaena.
• It contains 2-3% nitrogen when wet and also produces organic matter in the soil.
• The Azolla Anabaena combination type biofertilizer is used in the whole world. 
• The only constraint in azolla is that it is an aquatic plant and water becomes a limiting factor in growing it particularly in the summer months.
• Phosphorus Solubilising Biofertilizer:-
• Phosphorus is an important element required for plant growth. 
• This element is needed for nodulation by rhizobium.
• Some micro-organisms are capable of of solubilising immobilised phosphorus  making it available to plants for absorption.
• Mycorrhizal Fungi Biofertilizer:-
• It acts as a biofertizer and occurs naturally on roots of the forest trees and crop plants.
• The fungi has the ability to dissolve and absorb phosphorus that plant roots can not readily absorb.
• In soils low in nutrients, there is an increased absorption of nutrients by plants infected with Mycorhhiza.

Bio-Toilet

A toilet in which biological degradation of human waste by inoculates takes place is known as Bio-Toilet. 

Inoculums digests the human waste converting it into water & gases in the process.  

• The name of the bio-toilet bacteria type is Anaerobic Bacteria.

Steps  in anaerobic digestion:-

1. Large polymers are converted into simpler monomers called hydrolysis 
2. Simple monomers are converted into volatile fatty acids called acidogenesis 
3. Volatile fatty acids are converted into acetic acid CO2 & H2 called acetogenesis 
4. Acetate & H2 are converted into CH4 & CO2 called methanogenesis

Indian Railways is using the bio-toilet concept of the DRDO in which the bio-digester tank in every toilet is filled with inoculums containing four types of bacteria. The water trap system in the toilet prevents air from getting into the tank, the human waste is processed by anaerobic bacteria in seven chambers in the tank and the methane gas is allowed to escape into the air.

Fuel Cell

A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction of positively charged hydrogen ions with oxygen or another oxidizing agent.

• Hydrogen is the basic fuel, but fuel cells also require oxygen. One great appeal of fuel cells is that they generate electricity with very little pollution–much of the hydrogen and oxygen used in generating electricity ultimately combine to form a harmless byproduct, namely water.

The purpose of a fuel cell is to produce an electrical current that can be directed outside the cell to do work, such as powering an electric motor or illuminating a light bulb or a city. Because of the way electricity behaves, this current returns to the fuel cell, completing an electrical circuit.

• A single fuel cell generates a tiny amount of direct current (DC) electricity.

Difference between Fuel Cell and Batteries:-

Fuel cells are different from batteries in that they require a continuous source of fuel and oxygen or air to sustain the chemical reaction, whereas in a battery the chemicals present in the battery react with each other to generate an electromotive force (emf). 

• Fuel cells can produce electricity continuously for as long as these inputs are supplied.

Different types of fuel cells:-

Alkali fuel cells operate on compressed hydrogen and oxygen. They generally use a solution of potassium hydroxide (chemically, KOH) in water as their electrolyte. Efficiency is about 70 percent, and operating temperature is 150 to 200 degrees C, (about 300 to 400 degrees F). Cell output ranges from 300 watts (W) to 5 kilowatts (kW). 

• Alkali cells were used in Apollo spacecraft to provide both electricity and drinking water. They require pure hydrogen fuel, however, and their platinum electrode catalysts are expensive. And like any container filled with liquid, they can leak.

Molten Carbonate fuel cells (MCFC) use high-temperature compounds of salt (like sodium or magnesium) carbonates (chemically, CO₃) as the electrolyte. Efficiency ranges from 60 to 80 percent, and operating temperature is about 650 degrees C (1,200 degrees F). Units with output up to 2 megawatts (MW) have been constructed, and designs exist for units up to 100 MW. The high temperature limits damage from carbon monoxide "poisoning" of the cell and waste heat can be recycled to make additional electricity. Their nickel electrode-catalysts are inexpensive compared to the platinum used in other cells. But the high temperature also limits the materials and safe uses of MCFCs–they would probably be too hot for home use. Also, carbonate ions from the electrolyte are used up in the reactions, making it necessary to inject carbon dioxide to compensate.

Phosphoric Acid fuel cells (PAFC) use phosphoric acid as the electrolyte. Efficiency ranges from 40 to 80 percent, and operating temperature is between 150 to 200 degrees C (about 300 to 400 degrees F). Existing phosphoric acid cells have outputs up to 200 kW, and 11 MW units have been tested. PAFCs tolerate a carbon monoxide concentration of about 1.5 percent, which broadens the choice of fuels they can use. If gasoline is used, the sulfur must be removed. Platinum electrode-catalysts are needed, and internal parts must be able to withstand the corrosive acid.

Proton Exchange Membrane (PEM) fuel cells work with a polymer electrolyte in the form of a thin, permeable sheet. Efficiency is about 40 to 50 percent, and operating temperature is about 80 degrees C (about 175 degrees F). Cell outputs generally range from 50 to 250 kW. The solid, flexible electrolyte will not leak or crack, and these cells operate at a low enough temperature to make them suitable for homes and cars. But their fuels must be purified, and a platinum catalyst is used on both sides of the membrane, raising costs.

Solid Oxide fuel cells (SOFC) use a hard, ceramic compound of metal (like calcium or zirconium) oxides (chemically, O₂) as electrolyte. Efficiency is about 60 percent, and operating temperatures are about 1,000 degrees C (about 1,800 degrees F). Cells output is up to 100 kW. At such high temperatures a reformer is not required to extract hydrogen from the fuel, and waste heat can be recycled to make additional electricity. However, the high temperature limits applications of SOFC units and they tend to be rather large. While solid electrolytes cannot leak, they can crack.

Source:-

1. http://americanhistory.si.edu/fuelcells/basics.htm
2. https://en.wikipedia.org/wiki/Fuel_cell

Project Zero

• Google is setting up a crack team of hackers to protect internet users from government snooping and cyber attacks.
• The firm says its 'project zero' will look at everything from accidental flaws in code, known as zero day bugs, to major government operations.
• It also aims to make Google's own service more secure, and make encryption easier for people to use.