Saturday, August 13, 2016

Biofertilizers

Dr Rashmi Tyagi
Associate Professor and HoD
The NorthCap University, Gurgaon

Biofertilizers are microorganisms (bacteria, cyanobacteria andfungi) which enhance the availability of nutrients, like nitrogen and phosphorus,to the crop plants. In addition to nitrogen/phosphorus they also provide organic carbon, various growth promoting substances and improves the physical properties of the soil. With the introduction of high-yielding crop varieties, demand for chemical fertilizers has been increased severalfolds. Further, crop plants are able to use only about 35% of the applied chemical fertilizer as considerable amount is continuously lost from the soil due to leaching, denitrification and volatilization. There are also many ecological limitations to the heavy use of chemical fertilizers - the concentration of toxic nitrate has been found to be increased in water bodies near heavily fertilized fields.Denitrification of nitrate produces nitrogen gas and small amount nitrousoxide (about 10 %) and the latter being a green house gas results in global warming and health hazards.

Unlike chemical fertilizers which have various environmental impacts,biofertilizers are economical, ecofriendly and have long - term sustainability. For optimum crop yields biofertilizers are generally used incombination with the chemical fertilizers. Some micro-organisms with practical or potential application as biofertilizer are Rhizobium, Nostoc, Azotobacter, etc.

Rhizobium sp. are symbiotic N -fixing 2bacteria forming pink coloured rootnodules in leguminous plants, like gram,mung, pea, pigeonpea (arhar dal) (Fig. 1).These bacteria inside the nodules fix atmospheric nitrogen into ammonia with the help of the enzyme nitrogenase. The estimated N fixed by Rhizobium ranges 2from 50-150 kg/ha/year and increases the yield by 10-15%. The culture of Rhizobiumis grown in incubators orfermenters and mixed with a carrier material like peat.Seeds coated with this biofertilizer are used for sowing in the fields.


Azotobacter
is a freelivingN -fixing 2bacterium used for the crops wheat, rice,and vegetables and is capable of fixing 15-30 kg N/ha/year. Azospirillumsp. are found in association with roots of many plants ofgrass family like jowar, wheat, bajra, etc.and provides about 15-30 kg N/ha/year.

Cyanobacteria (blue-green algae) arephotosynthetic, prokaryoticmicroorganisms and many of them fixatmospheric N , e.g. Nostoc, Anabaena, 2Aulosira, Tolypothrix, etc. (Fig.2).Cyanobacterial biofertilizer are preferably used in tropical rice fields where they contribute 20-30 kg N/ha/year. Moreover,after application for 3-4 successive years in the field, a sufficient population builds upand their further application in the field is not required. They are also useful inreclamation (curing) of alkaline and saline soils. Cyanobacterial biofertilizers are grown in small tanks or ponds in the sunlight and the sun-dried biomass is used to sprinkle the rice field.

Azolla is a water fern harbouring symbiotic cyanobacterium Anabaena azollaein thecavity of its leaves. It is widely used as biofertilizer in rice fields of temperate countries, like Vietnam (Fig. 3).


Phosphate Solubilizing Bacteria (PSB)are species of Pseudomonas, Bacillus,Thiobacillus, etc. which convert insolublenon-available inorganic phosphorus (rockphosphate) present in the soil intosoluble phosphorus utilized by the cropplants.

Vesicular Arbuscular Mycorrhizal(VAM) Fungi e.g. Glomus, are found inassociation with roots of plants; some atthe surface of roots (ectomycorrhizae)whereas others inside the roots(endomycorrhizae). They have multiple benefits converting non-available phosphorus into available forms,producing growth promoting substances and protecting crop plants against soil pathogens. These fungi are yet to be exploited on a commercial scaleand in USA they are applied in Citrus crop by inoculating the seedlings with VAM.


Thus, if a part of the chemical fertilizer demand of the crop plants could be met through biofertilizer, a major in put constraint can be overcome. Though,field inoculation experiments are limited,the biofertilizer is expected to make important contributions to agriculture. In the long term, the modern methods ofbiotechnology will greatly improve the biofertilizer technology. It would bepossible to impart herbicide and insecticide resistance to promote competition against weedy micro organisms in the fields. For wide rexploitation of the biofertilizer technology in agriculture, a coordinated research in the laboratory and field is necessary.





Amazing 2-D Material - Graphene

Ms Pranati Purohit
Asst Professor
The NorthCap University, Gurgaon

Discovery of two-dimensional single atomic layer thick material has baffled scientists who never imagined that such a material could exist. In 2004 physicists,KS Novoselov, AK Geim and their colleagues first accidently made the Nobel prize winning discovery of this new wonder material in the peelings of the scotch tape, which was being used to clean the graphite surface. This one-atom thick material showed miraculous and confounding properties viz. 200 times stronger than steel, more conducting than silver, 98% transparent to light (yet it is visible to naked eye), impermeable to even the lightest hydrogen gas, easily amenable to modification in its properties. Its unsurpassed transparency and conductance can potentially replace the electrodes in touchscreens and solar cells. Further, the extremely high strength to weight ratio can integrate it into composite materials for lightning proof aircraft fuselages. Being impermeable would make it perfect to use in hydrogen reservoirs.

Isolation
 
At present, the most popular approaches to graphene isolation are electrochemical exfoliation. In one experiment the researchers have been able to produce approximately 16.3 g of graphene (area of about 16 football fields) in 30 minutes using graphite and Pt electrodes in an ammonium salt electrochemical bath.Exfoliation is not suited to the electronics industry. Growth on metals and subsequent transfer to insulating substrates, and thermal decomposition of SiC to produce so called epitaxial graphene on top of SiC wafers have the potential for producing wafer-scale graphene.


Electronic properties

Graphene exhibits a variety of transport phenomena that are characteristic of 2D Dirac fermions, such as specific integer and fractional quantum Hall effects, a ‘minimum’ conductivity of ~4e2/h even when the carrier concentration tends to zero.Suspended samples of graphene show mobility (μ) of up to 106 cm2 V-1 s-1. It also shows near-ballistic transport at room temperature. Large-area graphene is a semimetal with zero bandgap. Its valence and conduction bands are cone-shaped and meet at the K points of the Brillouin zone. Due to zero bandgap, graphene cannot be configured in a switch and hence is not suitable for logic applications unless its band structure isopened. This has become possible in a number of ways: by constraining large-area 2-D graphene in one dimension to form graphene nanoribbons, by biasing bilayer grapheneand by applying strain to graphene. Graphene has been made luminescent by chemical and physical treatments to produce quantum dots. Graphene has plasmonic excitations in terahertz and mid-infrared and has emerged as a unique material for electronic applications in this frequency range such as THz lasers, amplifiers, detectors, etc.

Applications

Graphene has changed from being the exclusive domain of condensed matter physicists to being explored by electron-device community. In particular, graphene-based transistors have developed rapidly and are now considered an option for post-silicon electronics. Graphene is considered as an ideal material for energy storage and conversion. During the past several years, a variety of graphene based materials (GBMs) have been successfully prepared and applied in super-capacitors, lithium ion batteries, water-splitting, electrocatalysts for fuel shells and solar cells. As graphene is a conductive yet transparent material, with low cost and low environmental impact, it is an ideal material for manufacture of sensors and biosensor-based devices in various transduction modes, from electrical and electrochemical transduction to optical transduction.

Industry giant IBM has produced several electronic component prototypes. Flat screens (70cm in the diagonal) with graphene electrodes, tennis rackets made with graphene have been championed by some industries.

Conclusion and outlook

The speed of development in graphene products in the last ten years is much faster than the typical 40years it takes for a new material to move from an academic lab into a consumer product. Governments and industries around the world have earmarked billions of dollars on research and development of graphene products. It would not be out of place to say graphene as the fastest developing material known so far.According to recent reports on thefuture of graphene, a market worth $1.5bn in 2015 and $7.5bn in 2025 is forecasted.

The APPLE OF OUR EYES: STEVE JOBS(1955-2011)

Ms Jyotika Pruthi
Assistant Professor
The NorthCap University, Gurgaon

Many years ago an apple dropped from a tree and landed on a man resting in the shade of the tree.That man was Sir Isaac Newton and THAT apple created history,it led to the ‘discovery’ of Gravity.Several years later, in 1976 to be precise, another Apple,this time a half–eaten one, set out to create history.The man behind this Apple was a simple guy from San Francisco,Steve Jobs.

Steve Jobs,born on 24 February 1955,lost his battle to cancer on October 5, 2011, after putting up a brave fight for seven years.He was 56.

This charismatic leader, entrepreneur,innovator co-founded Apple with friends Steve Wozniak and Ronald Wayne.Together,the team came out with Apple II which crushed all competition and became the symbol of the personal computing revolution worldwide. Surprisingly, Jobs was fired from Apple in 1985for being an “erratic” and “temperamental” manager.


In a speech Jobs gave at Stanford University in 2005,he said that being fired from Apple was the best thing that could have happened to him, “The heaviness of being successful was replaced by the lightness of being a beginner again, less sure about everything. It fired me to enter one of the most creative periods of my life”.And surely it was a boon in disguise for him.The same year he founded NeXT Inc., a computer company.NeXT Inc. proved to be very successful and in 1996 Apple bought the company for $429 million,making Steve Jobs the CEO of the company he co-founded.He added “I’m pretty sure none of this would have happened if I hadn’t been fired from Apple.It was awful-tasting medicine, but I guess the patient needed it.”

Not much is known about Steve Job’s visit to India.This cult figure came to India in the early 70’s in search of ‘enlightenment’ and ‘nirvana’ and went back unsatisfied.The hot, uncomfortable summer made Jobs question many of the illusions he had nursed about India.He found India far poorer than he had imagined and was struck by the incongruity between the country’s condition and its airs of holiness.[1]

The iREVOLUTION

The announcement that Apple, a computer company, would be making a portable music player met with a lot of skepticism.But Job’s true genius lay in integrating great ideas in ways not envisioned before.He simply said, “We at Apple love music, andit’s always nice to do things we love”. As predicted by him,iPod was an amazingsuccess. Its beautiful design, brilliant user interface, smart click wheel and most importantly, its ability to sync with iTunes made it sell like hot cakes.

After this there was no stopping for Apple.It pushed itself to innovate more and more and came up with the iPod Mini in 2004 and the iPod Nano in 2005.It expanded its Music store internationally and became the undisputed leader of the new digital music trend.A noticeable milestone was passed in 2006 when Apple’s revenues from iPod equaled those made on computers.

The biggest and the most popular launch from their stable was undeniably iPad, Apple’s iOS –based tablet phone.This multi –touch display cell phone, that included the features of an iPod and, with its own mobile browser, revolutionized the mobilebrowsing scene.

What distinguishes Apple from other companies, and perhaps the best asset they have is the user friendly nature of their products leading to hassle-less computing experience.None of their products come with complicated long serial codes,and do not require repeated authentication.

iMISS

Yes,Steve Jobs has changed the way the world lives.He has touched millions of lives in his short lifetime. He was a technologist and an innovator who defined consumer culture.The vision of this college dropout gave birth to one of the most influential corporations in the world, made massive contribution to the computer,mobile and music industry and made him a multimillionaire. His passion towards life made him survive all turbulences in his life.

Today Steve Jobs is not amongst us, but his legacy lives on in the technology which we all love using. We hope he hears the love and wishes of millions of fans from somewhere above in his patented black turtleneck and jeans   


[1] The Little Kingdom – The Private Story of Apple, Author Michael Moritz