Science ReporterCurrent- 2013Ravi P. Agrahari(Science &Technology)
Science Reporter issues (Current-2013)June 2012- Coal fly ash in agriculture- beneficial orrisky ?July 2012 :-- Salt tolerant Salicornia- Journey of milk to the consumer- Probiotics- Adulteration in milkAugust 2012 :-- Superstar superbugsSeptember 2012:-- Mobile phone application- Polished rice smoothens path to diabetesOctober 2012:-- CSIR@70- XNANovember 2012:-- India in Alice experiment- Gravitational wave observatory- Silver hut experimentDecember 2012:-- Global dimming- Nobel Prize in Physics, Medicine andChemistry- Silicon life beyond
Conceptual Topics Discussion• India in Alice experiment• Gravitational wave observatory• XNA• Superabsorbent Polymer (SAP)• Outsmarting the Superbugs• Milk Process• Coal fly ash in agriculture- beneficial or risky ?
Indian scientist are involved in a very existing research program as part of theALICE experiment at CERN since last two decades. Components of the ALICEdetector like he Photon Multiplicity Detector and Muon Spectrometer areproducts of Indian scientific and industrial excellence. The Quark Gluon Plasmaresearch program at ALICE is on the quest to unearth the physics ofdeconfinement and vacuum, and to get a glimpse of how matter behavedwithin a few microseconds after the birth of our Universe.Our universe began with a Big Bang about 13.7 billion years ago. A fewmicroseconds from the beginning, this hot and dense matter around us ismade up of molecules, which are clusters of atoms bound together byelectromagnetic forces. The atom consists of a dense central nucleus, madeup of protons and neutrons and surrounded by cloud of negatively chargedelectrons. Inside the protons and neutrons, quarks are bound together by aforce known as strong interaction, mediated by the exchange of force carrierparticles called gluons.
Universe begin Big Bang│In first few instant of time (micro second)│A hot and dense matter form called“Quark- Gluon plasma”(Hadron is a composite particle of Quark and Gluon)│Inside proton and neutron, quarks are bound together by a force known asstrong interaction, mediated by the exchange of force carrier particlescalled gluons.│The strong interaction is in fact responsible for binding the protons andneutrons together inside the atomic nuclei. There are six types of quarks:up, down, strange, charm, bottom and top. The up and down quarks makeup the protons and neutrons.
Quarks have various intrinsic properties like electric charge, colour charge,mass and spin. Gluons are exchange of photons in the electromagnetic forcebetween two charged particles. Quarks and gluons behave like free particleswhen they are very close together, but feel much stronger forces if they areseparated. This unique properties of quarks and gluons is known asasymptotic freedom. Because of asymptotic freedom quarks are neverdirectly observed in isolation, and are confined within composite particlescalled hadrons.The current theory of strong interaction, Quantum Chromo Dynamics (QCD),predicts that at very high temperatures and high energy densities, quarksand gluons are no longer confined inside the hadrons. Instead, they wouldexist freely in the form of free quarks and gluons, a state called Quark GluonPlasma. The Quark Gluon Plasma state is relevant to questions about theorigin of the universe within the first few microseconds of the birth of theuniverse, conditions of extremely high temperature and energy densityexisted and the primordial state of matter was a system of QGP.
Thus, to understand the evolution of our universe during its infancy,we need to create and study the formation of QGP in the laboratory.This is done by colliding two heavy nuclei (such as gold on gold or leadon lead) together at very high energies. In this collision process, it ispossible to compress and heat the colliding nuclei in such a way thattheir individual protons and neutrons overlap. This creates a region ofhigh energy density. By inducing head on collision of lead nuclei,accelerated by the Large Hadron Collider (LHC) to a speed close to thatof light we aim to obtain- albeit over a tiny volume of the size of anucleus and for an infinitesimally short instant- a QGP state. We thenobserve this QGP state as it reverts to hadronic matter throughexpansion and cooling. Probing the hot and dense matter produced inhigh-energy heavy-ion collisions is one of the major tasks of theexperiments at the LHC.
The ALICE (A LARGE ION COLLIDER EXPERIMENT) experiment isdevoted to the search and study of QGP in the laboratory. Two otherLHC experiments, CMS and ATLAS also have excellent programs forQGP research. We are probing the properties of vacuum, and getting aglimpse of how matter behaved immediately after the Big Bang.The two major Indian contributions to the ALICE detector systems fromIndia include the Photon Multiplicity Detector (PMD) and MuonSpectrometer. These two detectors have been fully operational andcontinue to collect data, contributing to the strong physics programmeof ALICE.
Gravitational wave observatoryMEGA SCIENCE PROJECTIndia will soon be joining a global network ofGravitational Wave Observatories
India is geared to add a new dimension to 21st century astrophysics bysettling up a state-of-the-art ‘Gravitational Wave observatory’ (GWO) incollaboration with the United States of America as part of a globalnetwork.The proposal for the $290 million dollar facility is pending approval ofthe Government of India. The Indian scientists are confident that theunion cabinet will soon clear the ‘mega science project’ that involvedsanction of Rs. 1260 crores to be spent over the next 15 years (2012-2027).The prestigious project, codenamed IndlGO, aims at construction andsubsequent fifteen year operation of an advanced interferometricgravitational wave detector in India, called LIGO-India in collaborationwith USA’s LIGO laboratory.
LIGO, which stands for the Laser Interferometer Gravitational-WaveObservatory, is a large-scale physics experiment aiming to directlydetect gravitational waves, cofounded in 1992. It is sponsored bythe National Science Foundation (NSF). At the cost of $365 million (in2002 USD), it is the largest and most ambitious project ever funded bythe NSF.The international LIGO Scientific Collaboration (LSC) is a growing groupof researchers, over 800 individuals at roughly 50 institutions, workingto analyze the data from LIGO and other detectors, and working towardmore sensitive future detectors. The current spokesperson for the LIGOScientific Collaboration, re-elected in March 2013, is Louisiana StateUniversity Professor of Physics and Astronomy, Gabriela González.
What are Gravitational Waves ?“Gravitational waves” (GWs) akin to the electro-magnetic waves, havebeen detected from the Universe. The GWs are emitted by gravitatingbodies in motion, such as two ‘black holes’ spiralling towards eachother in a binary orbit in the cosmos. Gravitational Waves areextremely difficult to detect, and although they were predicted aboutone hundred years ago, till today they have not been seen inexperiments. There is irrefutable indirect evidence that they do exist-this evidence comes that the compact binary orbit of a pair of stars isshrinking due to the emission of gravitational waves.
(Binary star systems : systems with two stars bound together by theirgravity, are actually quite common. While all binary systems orbit theirmutual center of gravity, not eclipsing. This actually has more to dowith us then it does with the distant star systems. If we view a binarysystem from the top or bottom, then one star does not pass in front ofthe other from our perspective and the amount of light we see from astar system does not vary. However, if we are happen to be lookingright down the side of a binary system, one stars passage in front of theother can will cause the light from the other star to be blocked, and theamount of light coming in from the binary system will dim. Of course,binary systems are often comprised of two stars of differentluminosities. When the brighter of the two stars eclipses the dimmerstar, the drop in brightness is small, and we call this the secondaryminimum. When the dimmer star eclipses the brighter, the drop islarger, and we call this the primary minimum.)
The experimental discovery of gravitational waves will open anextraordinary new window in astronomy, what is often known asgravitational wave astronomy. Just as astronomers have been studyingthe universe for centuries using electromagnetic waves, they will in thefuture be able to study it with gravity waves. Great experiments arecurrently in progress worldwide, using ‘Gravitational Wave Detectors(GWD), to find gravitational waves.(Gravitational waves: Violent events, such as the collision of two blackholes, are thought to be able to create ripples in space-time knownas gravitational waves. The Laser Interferometer Gravitational WaveObservatory is presently searching for the first signs of these tell-taleindicators).
In 1905, Albert Einstein determined that the laws of physics are the same forall non-accelerating observers, and that the speed of light in a vacuum wasindependent of the motion of all observers. This was the theory of specialrelativity. It introduced a new framework for all of physics and proposed newconcepts of space and time.Einstein then spent ten years trying to include acceleration in the theory andpublished his theory of general relativity in 1915. In it, he determined thatmassive objects cause a distortion in space-time, which is felt as gravity.General relativity is a theory of space and time created by Albert Einstein andpublished in 1915. The central idea of general relativity isthat space and time are two aspects of spacetime, which is curved in thepresence of gravity, matter, energy, and momentum. The relationshipbetween these forces is shown in the Einstein Field Equations. Onemathematical formula for General relativity is , although there are manymore equations.In general relativity, freefall is inertial motion instead of being at rest on amassive body such as the Earth, as described by the equivalence principle.
General relativity has made many successful predictions. These include:The bending of light as it passes the Sun by twice the Newtonian value for anobject travelling at the speed of light. This was confirmed by Eddington in1919, and the announcement forced scientists to take general relativityseriously.The perihelion of the planet Mercury advances more than is expectedunder Newtonian physics. General relativity accounts for the differencebetween what is seen and what is expected without it.The gravitational redshift effect, by which the wavelength of light increases asit moves away from a massive object. This was confirmed by the Pound-Rebkaexperiment.The Shapiro delay, under which light appears to slow down as it passes close toa massive object. This was first confirmed in the 1960s by space probes headedtowards the planet Venus.
MissionLIGOs mission is to directly observe gravitational waves of cosmic origin.These waves were first predicted by Einsteins general theory ofrelativity in 1916, when the technology necessary for their detection didnot yet exist. Gravitational waves were indirectly suggested to existwhen observations were made of the binary pulsar PSR 1913+16, forwhich the Nobel Prize was awarded to Hulse and Taylor in 1993.Direct detection of gravitational waves has long been sought. Theirdiscovery would launch a new branch of astronomy tocomplement electromagnetic telescopes and neutrino observatories.
In August 2002, LIGO began its search for cosmic gravitational waves.Measurable emissions of gravitational waves are expected from binarysystems (collisions and coalescences of neutron stars or blackholes), supernova of massive stars (which form neutron stars and blackholes), accreting neutron stars, rotations of neutron stars with deformedcrusts, and the remnants of gravitational radiation created by the birthof the universe.The observatory may in theory also observe more exotic currentlyhypothetical phenomena, such as gravitational waves caused byoscillating cosmic strings or colliding domain walls. Since the early1990s, physicists have believed that technology has evolved to the pointwhere detection of gravitational waves—of significant astrophysicalinterest—is now possible.
ObservatoriesLIGO operates two gravitational wave observatories in unison: the LIGOLivingston Observatory in Livingston, Louisiana, and the LIGO HanfordObservatory, on the DOE Hanford Site, located near Richland, Washington.These sites are separated by 3,002 kilometers (1,865 miles). Since gravitationalwaves are expected to travel at the speed of light, this distance corresponds toa difference in gravitational wave arrival times of up to ten milliseconds.Through the use of triangulation (triangulation is the process of determiningthe location of a point by measuring angles to it from known points at eitherend of a fixed baseline, rather than measuring distances to the point directly),the difference in arrival times can determine the source of the wave in the sky.Each observatory supports an L-shaped ultra high vacuum system, measuring 4kilometers (2.5 miles) on each side. Up to five interferometers (Interferometrymakes use of the principle of superposition to combine waves in a way thatwill cause the result of their combination to have some meaningful propertythat is diagnostic of the original state of the waves) can be set up in eachvacuum system.
There are two detectors in the USA under LIGO Laboratory while thethird one GEO is in Hannover (Germany) now under upgrade withpioneering advanced optical technologies.An advanced LIGO version of the VIRGO with advanced seismicisolation system is also operational near Pisa in France with UScollaboration since May 2007.A $100- million Large Cryogenic Gravitational Telescope (CGWT), to beready by 2017, is under construction in an underground Kemijoki minein Japan as part of the network.
LIGO-IndiaLIGO-India is a collaborative project proposed by the LIGO Laboratoryand the Indian Initiative in Gravitational Observations (IndIGO) tocreate a world-class gravitational-wave detector in India. The LIGOLaboratory, with permission from the U.S.National Science Foundation and Advanced LIGO partners from the U.K,Germany and Australia, has offered to provide all of the designs andhardware for one of the two planned Hanford Advanced LIGO detectorsto be installed, commissioned, and operated by an Indian team ofscientists in a facility to be built in and by India.
The project requires the support and agreement of both governments inaddition to the LIGO Laboratory and IndiGO. The project was discussedat a Joint Commission meeting between India and the US in June2012. In parallel, the proposal was evaluated by LIGOs funding agency,the NSF.As the basis of the LIGO-India project entails the transfer of one ofLIGOs detectors to India, the plan would affect work and scheduling onthe Advanced LIGO upgrades already underway.In August 2012, the U.S. National Science Board approved the LIGOLaboratorys request to modify the scope of Advanced LIGO by notinstalling the Hanford "H2" interferometer, and to prepare it instead forstorage in anticipation of sending it to LIGO-India. In India, the projecthas been presented to the Department of Atomic Energy and theDepartment of Science and Technology for approval and funding. Finalapproval is pending
The IndlGO Consortium Institutions include Chennai MathematicalInstitute, IISER-Kolkata, IISER-Pune, IISER-Thiruvananthapuram, IIT-Madras, IIT-Kanpur, IPR, IUCAA-Pune, RRCAT-Indore and University ofDelhi.According to the proposal document, the major funding in the XII Plan isRs. 650 Crores for the construction of the detector. During the XIII 5-yearPlan (2017- 22) the expected expenditure is Rs. 380 Crores, out of whichRs. 280 Crores is for completing the construction and installation of thedetector and the remaining Rs. 100 Crores for continuous operation andmaintenance.The XIV Plan will see mature gravitational wave astronomy with theLIGO-India detector. Projected operation cost for continuous operationand maintenance during this period (2022-27) is Rs. 230 crores. Thus,the total projected expenditure for 15 years spanning three plan periodsfrom 2012-2027 is Rs. 1260 Crores.
These have the potential to seed technologies spin-offs in several areasthat include ultra-stable and high power lasers, high-tech optics, sensorsand vibration isolation platforms, multi-channel control systems, largevolume data storage, retrieval computing and fast networkcommunications and quantum technologies for communication.LIGO-India will be transformational for Indian physics, technology andastronomy and will drive accelerated growth in these areas overdecades. The partnership with LIGO moves the gravitational wavedetector project to a state of readinessthat would normally takedecades to achieve.For the LIGO-India project, the US and its international partners (UK,Germany and Australia) will contribute complete design and hardwareof the detector worth $140 million (650 crores).
XNA(New Twist in Molecular Genetics)The newly synthesized nucleic acid, XenonucleicAcid, offers exciting possibilities in scientificresearch and understanding the bounds of what itmeans to be alive.
This thinking changed in a breakthrough in molecular genetics in April 2012when Vitor Pinheiro and Philip Hollinger and their team at the MRC laboratoryof Molecular Biology, Cambridge, UK developed six alternatives polymerscalled XNAs. These XNA molecules can store genetic information and evolvethrough natural selection. The discovery forms a turning point in the era ofsynthetic genetics, which expands the chemistry of life in new uncharteddirections.(Xenonucleic Acid) XNAThis thinking could soon change, synthetic biologists from MRC laboratoryunder the leadership of Vitor Pinheiro and Philip Hollinger have developed sixalternatives polymers called XNAs that can also store genetic information,replicate and evolve like the genetic systems consisting of DNA and RNA. The“X” in XNA stands for “xeno” a latin prefix that means exotic of foreign.Scientist have used this term to indicate the synthetic nature of thesemolecules- that one of the ingredients typically found in the building blocksthat make up RNA and DNA has been replaced by something different fromwhat occurs naturally.
How was XNA synthesized?Under normal conditions DNA Polymerase is highly specific about the bases itattaches and only selects bases with a deoxyribose sugar so that it assemblesDNA, rather than any other nucleic acid. Pinheiro and his team modified theexisting enzyme using a genetic engineering technique calledcompartmentalized self-tagging (or “CST’) and created mutants of this DNAPolymerase so that it prefers to use the building blocks of XNAs with othertypes of sugars instead of the normal bases for DNA.
He also created an enzyme that could do the reverse – convert XNA intoDNA. Of course, no natural enzyme can even begin to do this, so theevolution trick didn’t work in this direction. Instead, Pinheiro used amore brute-force approach: he took a different polymerase, randomlymutated it, and looked for versions that could do the XNA-to-DNAconversion. Eventually, he moulded one.Pinheiro ended up with enzymes that could copy information betweenXNA and DNA, with an accuracy of 95 per cent or more. With morework, it should be possible to cut DNA out of the loop altogether, so thatXNAs can be directly built from XNAs. If this is possible, Szostak adds, “Inthe longer run, it may be possible to design and build new forms of lifethat are based on one or more of these non-natural genetic polymers.”
There are already hints of this. The team has so far managed to copyFANA and FANA, CeNA from CeNA, and even HNA from CeNA. However,all these steps were far less efficient than working through DNA. ButHolliger says that there would be few benefits to abandoning themiddle-man, because “it’s convenient to go through DNA.”That’s because all of our genetic technology is geared to our standardnucleic acids. If we moved towards XNA-only experiments, we wouldalso have to tweak our sequencing tools and cloning techniques tomatch.
Implications of XNA SynthesisScientist consider the discovery of XNAs extremely important owing totheir far reaching implications and their special properties.Synthetic life : it is believed that XNAs might, in future, help in thecreation of synthetic genetic systems based on alternative chemicalplatforms, and hence entirely synthetic alternatives novel forms of lifethat will not require DNA or RNA for functioning.Origin of Life : some researchers believe that life might have been basedon simpler genetic systems before the emergence of RNA and DNA.
Medicine and Therapeutics : generally biomolecules like RNA, DNA,enzymes and antibodies are used as therapeutics, diagnostics and inbiosensing applications. But a serious drawback of this technique is theshort lifespan of such treatments and the difficult time they have inreaching their therapeutic targets as they are degraded quickly in thestomach. In such a scenario, XNA can be used as a potential therapeuticagent targeting diseased cells as they are more resistant to degradationand biological systems don’t have enzymes evolved enough to digestthem.Exobiology : is the branch of science that is involved with looking for lifeon other planets. Emergence of XNA as a molecule that can storeinformation, replicate and evolve suggests that DNA and RNA no longermight be the only markers for the search of life and that life forms basedon XNA might exist on other planets.
Superabsorbent Polymer (SAP)SAP are polymers that can absorb and retain extremely large amounts ofa liquid relative to their own mass. SAPs are used in diapers as well as toretain water in soil.Take 2-3 grams of poly acrylic acid sodium salt (sodium polyacrylate) in a100 ml plastic or glass beaker. Add 20-30 ml of water in to it. Formationof SAP takes place in 10-15 seconds.
Outsmarting the SuperbugsSuperbugs have evolved into a serious communityhealth problem. Will be able to conquer themenace that we have ourselves created throughthe indiscriminate use of antibiotics ? scientists areworking hard to counter this challenge.
When a person is treated with antibiotics, about 30% is absorbed andthe rest passes through the body into the sewage system. Antibiotics arenot readily degraded. Ultimately the sewage enters a treatment plant,which encourages the growth of bacteria to digest the sewage. Duringthis process, in the presence of low levels of antibiotics, some bacteriamay develop resistance.Thus, in a large population of bacteria there may be a few that havedeveloped resistance to antibiotics. When an infected person is treatedwith antibiotics, the susceptible ones perish, leaving behind theresistant ones, which will multiply at the opportune moment. Next timewhen the same antibiotic is given to the patient, it may not be effectivein controlling the infection. When a class of bacteria becomes resistantto a particular drug, the pharmacologist develops a new kind ofantibiotic. It takes more than a decade to develop an antibiotic and thebacteria become resistant to even the new drug in due course.
What antibiotics do ?Antibiotics are designed to block some essential steps in the lifecycle of thebacteria and prevent their growth and survival. These include synthesis of cellwall, folic acid, DNA, RNA and protein. Since many of these processes occur inthe host cell (human and animal cells) also, targets chosen are specific to thebacteria, so that the drug may not harm the host cells. For example, unlikehuman and animal cells, bacterial cells have a thick cell wall. Antibiotics of theclass beta-lactams (which includes penicillin) bind and inactivate an enzyme(called ‘penicillin binding protein’ PBP), which is essential for the synthesis ofthe cell wall. A bacterial cell without a robust cell wall cannot survive.Folic acid biosynthesis is another example how these tiny bugs defy mightyhuman efforts. Folic acid is required by both bacteria and humans for thesynthesis of nucleic acids and proteins. Unlike humans, bacteria cannot usepre-formed folic acid and synthesize their own folic acid. An important startingcompound for the synthesis of folic acid is para aminobenzoic acid (PABA).
Sulphonamides and other sulfa drugs are analogous to PABA and bacteria cannot distinguish between the two. These compounds compete with PABA inbiochemical reactions. When chosen, they block the synthesis of folic acid andthus the formation of nucleic acids and proteins, killing the bacteria.An essential step in DNA replication prior to cell division is the unwinding ofthe double stranded DNA molecule. This is carried out by an enzyme calledDNA gyrase. A class of antibiotics known as fluoroquinolones bind to bacterialDNA gyrase and inhibit DNA replication preventing bacterial growth.Rifamycins inhibit RNA synthesis in an analogous manner.Ribosomes are structures on which protein synthesis takes place. Tetracycline,Erythomycin and similar antibiotics bind to ribosomes to prevent proteinsynthesis.He first superbug appeared on the scene less than twenty years after thediscovery of the antimicrobial drug. Antibiotic resistance was first observed inStaphylococcus aureus against penicillin in 1947.
Superstar Superbugs :Bacterial classes like staphylococci, enterococci, pneumococci all havethe ability to become superbugs. There are strains of E. Coli resistant tofive variants of the drug fluoroquinolone.The best known superbug is the methicillin (a penicillin class antibiotic)resistant Staphylococci aureus (MRSA). Later strains are reported tohave developed resistant to a number of antibiotics like tetracycline,erythromycin, vanomycin, and linezolid. MRSA is commonly found onhuman skin and mucous membranes. It is easily contacted in placeslike gym, schools and hospitals. It is quite common in Europe, UK, andUSA. According to a report, in 2005 MRSA was responsible for nearly95,000 cases of serious infection with almost 19,000 hospital-relateddeaths in United States. MRSA has also been successful in transmittingresistance genes to a completely different species of bacteria-Enterococcus faecalis- making it resistant to vanomycin.
Another bacterium Streptococcus pneumonia- has been a major causeof community acquired infection such as upper respiratory infection,bronchitis, pneumonia, pharyngitis and meningitis. Even though it wasonce almost eradicated by penicillin. It has now developed significantresistance to penicillin, trimethoprim, sulfamethoxazole, macrolides,tetracyclins and fluoroquinolones and thus has become a majorproblem.Another well known superbug that is bothering public health authoritiesin the developing world is Mycobacterium tuberculosis. It is reportedthat tuberculosis kills about 1.7 million people around the world, ofwhich three to four lakh deaths occur in India due to the presence ofresistant strains like Multi Drug Resistance (MDR-TB) and ExtremelyDrug Resistance TB (XDR-TB). Now, Hinduja Hospital, Mumbai hasreported the isolation of yet another resistant strain known as TotallyDrug Resistant TB (TDR-TB), which is found to be resistant to twelvedrugs.
Recently a new resistant strain Klebsiella pneumoniae was detected in aSwedish patient of Indian origin.This produces an enzyme named New Delhi- beta- lactame-1. Whichinactivates a broad range of beta- lactam antibiotics.This gene NDM-1 can spread horizontally and at least twenty strains ofbacteria, each resistant to one or many antibiotics, are now known.
The milk goes through several processes that can be termed as “dairyprocess”. Dairy processing is an industrial operation in which milkcomponents are separated and re-constituted to produce desired milkproducts. From milking to consumption, milk may undergo a lot of dairyprocesses depending upon the product desired. Let us look at some ofthese processes.Cooling : microorganism growth is prevented by immediately chilling themilk to five degree Celsius or below. At this temperature, milk will retainits freshness for three to four days.
Standardization : if milk has to be sold as buffalo milk, the minimum fatpercent should be standardization to 6% for most of the states in India. Milkmay be standardized to full cream milk; Toned milk, Double Toned milk etc. Fullcream Milk should contain minimum 6.0% fat and 9.0% Solids not fat (SNF)while standardized milk should contain minimum 4.5% fat and 8.5% SNF.Toned Milk and double Toned Milk should contain minimum 3.0% fat and8.5% SNF and minimum 1.5% fat and 9.0% SNF, respectively.Pasteurization : Pasteurization kills all pathogens and most of the spoilage typeof microorganisms. For this purpose milk is heated to such a time- temperaturecombination that ensures destruction of even the most heat resistantpathogen. Mycobacterium (TB germ) is the most heat resistant pathogen and itis taken as the index for deciding pasteurization temperature. Pasteurizationmay be done by two methods – Low temperature Long Time (LTLT) or HighTemperature Short Time (HTST). Now a days, the HTST method is mostly used.After Pasteurization, the milk must be immediately cooled down to fivedegree Celsius or below so that the surviving microorganisms do not multiplyfurther.
Cream Seperation : in cream separation, fat is removed from the milk bypassing it through a cream separator in which it is rotated at a very highspeed (around 8000 revolutions per minute) in thin films. Milk cream orfat, being lighter (specific gravity 0.9), remains in the centre while theskimmed milk (skim milk contains all the constituent except fat), beingheavier (specific gravity 1.036), goes towards the periphery in the creamseparator. The separated cream and milk are collected from differentoutlets provided in the cream separator.Homogenization : the fat in milk is present in shape of fat globules thatare of different sizes. The size may range from 0.1 to 22 microns andgenerally it is from 2-8 microns. Homogenization is the process in whichfat globules are broken down mechanically to a size of about onemicron. Homogenization is generally used in reconstitution of milk andfat rich products like ice cream, condensed milk, sterilised flavouredmilk etc. Homogenised milk does not stick to the container and gives aviscous appearance and rich mouth taste.
Standardization : some bacterial spore may not get destroyed eventhrough boiling of milk. They are destroyed through sterilization, whichis the process of heating milk to 120 degree C for 30 seconds or 150degree C for 2-3 seconds so that a shelf life of six months of milk atroom temperature is ensured.Adulteration in MilkThe most common adulteration is water. This is added to increase thevolume of milk during loose milk distribution. The second category ofadulterants is the one that are added to mask the adulteration of waterin milk. These are added to increase the SNF level. The number of suchadulterants is very large. The most common are starch, matlodextrins,sugar, salt, urea and a lot more.
In addition, traders may also add other chemicals to milk. When milk istransported to farther places for distribution, the bacteria in milkdeteriorate it producing lactic acid. This lactic acid destabilizes theproteins in milk and when such milk is heated, it gets coagulated. Toprevent such curdling, traders and alkaline neutralizers like causticsoda and sodium bicarbonate so that the developed acidity isneutralised and milk does not curdle on heating.Another class of additives to milk may be preservatives. These aresubstances that have bacteriostatic or bactriocidal effects and preventthe growth of microorganism. This enhances, the shelf life of milk. Butaddition of these preservatives is illegal and such substances areharmful for human health. The most common preservatives arehydrogen peroxide and formalin.
Coal fly ash in agriculture-beneficial or risky ?
India has a vast coal reserve of 211 billion tonnes making coal one of themost extensively used fossil fuels for generating power. However ashcontent of forty to fifty percent in Indian coal presents an inherentproblem of ash disposal.The ministry of power, Government of India extimates that 1800 milliontonnes of coal use every year leading to generation of 600 milliontonnes of fly ash by 2031- 2032.Since fly ash is a fine powder, it could cause respiratory problems wheninhaled. It may also lower agricultural yields by settling on leaves andcrops. When added to soil indiscriminately, toxic metals such aschromium, silicon, mercury, lead and arsenic contained in fly ash couldenter the food chain harming animals and humans. Fly ash occurs asvery fine particles, having an average diameter of less than 10 µm, lowto medium bulk density, high surface area and very light texture.
Fly ash in agriculture- Improves permeability status of soil- Improves fertility status of soil/agriculture yield.- Improves soil textural properties and soil aeration.- Reduces soil bulk density and crust and compact formation- Improves water holding capacity/porosity.- Makes favourable and optimum soil pH for crops.- Provides several micronutrients such as Mo, B, Mn, Fe, Zn, Cu, etc.- Source of many macronutrients like Mg, S, K, P, Ca, etc.- Alternative for gypsum for reclamation of sodic soils and lime forreclamation of acidic soils.- Improves soil microbial activities in combination with other organicamendments.
Fly ash risk in agriculture- Uptake and accumulation of toxic heavy metals by crop plant.- Fatal effect on humans and cattle due to consumption of heavy metalcontaminated crops.- Ground water pollution due to heavy metal percolation down to earth.- Higher doses of FA in agriculture field may cause soil infertility.- The radiochemical pollution present in FA.