Sunday, October 28, 2018

How Old Are You?

Simple, straightforward question; but often the answer isn't either.   If only we could develop an Agemeter (or should it be Ageometer? )  just like the thermometer  for body temperature!. An  ageometer   with a  precision of 0.5  to give readings like 17.5,  18.0, 18.5, 19 .....    Age has always been important from the  medico-legal angle,  because  it bestows  varying levels of  rights and responsibilities on children, juveniles and adults and at times senior citizens. Currently a combination of methods are used to assess the age of an individual - examination of teeth, wrist bones etc.  But the error margins are often 3-4 years. 

Age Factor  has now spilled  beyond  medico-legal boundaries into  geo-political and socio-economic arena.  The recent mass  influx of refugees into  Europe is the single biggest  thrust  factor.   According to  recent reports  Europe has close to 4 million refugees.  As per the UN requirements,  asylum seekers   under the age of  18 are eligible for special benefits and that means  a drain on national resources.   A population fleeing from its war torn homeland can't  think of,  let alone pause to pick up  passports or birth certificates. Moreover families get separated often with none to vouch for the age of  orphaned youngsters. There is widespread   feeling that  refugees  deliberately forge their age to qualify for special benefit package.  With nationalism on the surge all over the world, resentment  against refugees are flaring up everywhere. 
    

It is in this context that  the Epigenetic Clock proposed  by Professor Horvath  (Dept. of  Genetics and Biostatistics, University of California, Los Angeles, USA) catches global attention.   There is scientific concurrence that   DNA methylation levels (referred to as DNAm), could be a measure of  the mammalian ageing process, though   the "How" and "Why" of the correlation remain blurred. Methylation  happens at the  cytosine nucleotide linearly attached to a guanine nucleotide. These are referred to as CpG sites.    Methylated CpG sites are thus  biomarkers, which have the potential to turn off genes. In his approach Prof Harvoth used  a special machine learning method  to identify  the biomarkers  located at informative genomic locations and then  an algorithm to predict the biological age.  Initially selecting  353 such sites,   Prof Horvath  demonstrated that this  method  could spell out the biological age for a majority of tissue  samples with a median error of 1.03 years.  However it is also a fact that  there were outliers with error margin as high as 5 years.  While scientists are focusing on improving the accuracy of the method,    Zymo a company based in Irvine, California bought exclusive rights for the technology.  DNAge Epigenetic Aging Clock service is now available for US$299.     

Tailpiece
The Old Town Hall  is one of the oldest buildings in Prague, dating back to 1338.  The astronomical clock installed in 1410  is the oldest, still ticking  astronomical clock in the world. 


Town Hall Tower with the
Astronomical Clock  




REFERENCES:









Sunday, September 30, 2018

Clearing the Waste : How the Brain does it

Hippocratus (460- 370BC) had alluded to a water channel that encircles the brain. But  it took  2000+ years for scientists  to  put together, piece by piece, a detailed  picture highlighting  its  physiological significance.  Thus now we refer to  the clear liquid  that "waters" the brain and spinal cord as  the cerebro-spinal fluid, CSF for short. Specialised  ependymal cells   in the inner cavity of the brain produce this liquid in  pulses.  Chemically   CSF is very much like  serum but with one major difference.  The Protein content in serum could be as high as 7000mg/dL, whereas CSF registers only about 35mg/dL.  We also know that CSF fulfils  multiple responsibilities in the brain, such as cushioning the brain, preserving its buoyancy, supplying nutrients   and   scavenging  waste.  The  complex network of channels through which CSF flows, together with  its associated  glial (neuronal) cells,  is collectively known as  the Glymphatic System.   As recent as in  in 2015, scientists spotted lymphatic vessels in the meninges too.  Meninges is  the three tiered protective  cover that shields   the brain and the spinal cord. It is now realised that the menengeal lymphatic  system  closely collaborates with the glymphatic system in waste removal from the brain.   
Courtesy: Wikipedia 

The CSF sweeps up the waste  and later  gets  partly absorbed into the venous circulation and partly   drained into the lymphatic system for downstream processing.  In young healthy adults, this process is rapid and regular.  But with age the process becomes sluggish and waste gets accumulated. A typical case in study is the Alzheimer's disease,  in which  amyloid plaques accumulate. This  debris in turn  interferes with and impairs neuronal function and also clogs the drainage pathway.  Of course it could as well be a combination of over-production of amyloid plaques and under performance of the clearance system.

Scientists were indeed astonished to find that the  glymphatic system is mostly dormant when we are awake and gets into fully active mode only when we are asleep.  Using sophisticated imaging techniques, it has been  demonstrated that the rate of waste clearance from the brain  increases by about 60% during the sleep cycle. Hence the extrapolation by Xie et al   that  the restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system. Scientists are exploring  the possibility of clearing the choked pathways as a novel approach for  managing  neurodegenerative diseases such as  Alzheimer's. 

Tailpiece:

It has been found that healthy bones  facilitate the production of  osteocalcin, a hormone necessary for memory retention.  Prof.Eric Kandel,    who received  Nobel Prize in 2000 for unravelling the neurological pathways of learning and memory, has this to say:  "If you walk two or three miles a day, you will release sufficient osteocalcin from your bones to combat non-Alzheimer's, age-related memory loss"

REFERENCES:





Saturday, September 1, 2018

The History and Chemistry of HOPE

Diamonds are rare; blue diamonds are even rarer, constituting   less than 0.2% of naturally occurring  diamonds.   Experts say that  there are only a handful of notable blue diamonds in the world. And  Hope  tops that list.  This  most unique, priceless,  brilliant  deep blue diamond  is  currently  held  most securely  at the  Smithsonian Museum, Washington DC.  More than 350 years ago, John Baptiste Tavernier,  a  French trader, traveler, fortune hunter held it in his palm and  exclaimed at the  beautiful violet,  but the usual color qualifier has always been Blue.   
  
Hope Diamond with lighting  (Courtesy Wiki)
The birthplace  of Hope  diamond has been identified to be  the mines of Golconda, India. Sometime during the   seventeenth century (some say1640), Tavernier reportedly  appropriated  a large, 112.5 carat  uncut blue crystal from a local. Tavernier  later traded it  for a price and position  to the French emperor  Louis XIV.  The king had it  chiselled and set  to a triangular shape of 67.2ct. It acquired the name  French Blue and  remained among the French Crown jewels until  revolution broke out in the  1790's.
 Tavernier's original sketch of French Blue Courtsey: wiki 
 


During the revengeful  loot and plunder of the royal household by the enraged  masses, French Blue  disappeared along with other crown jewels.  Later  during the early part of nineteenth century a brilliant blue stone surfaced in the London jewellery market. John Francillon, an English jeweller had his suspicions. There were speculations that this was indeed the French blue. However  whosoever owned it in the interim period had it reduced  in size  to 45.52 ct  and reshaped it - perhaps to escape  knowledgeable eyes-  before floating it in the market.  The blue stone eventually became a part of  the English crown jewels collection.  In 1830, Henry Philip Hope, a wealthy banker  purchased  it from the  English King George IV, purportedly as part of a debt settlement.   The gem acquired a  new, permanent  identity The Hope Diamond, a name that didn't change any further with changing ownership.  In 1958  Hope Diamond was donated   to the Smithsonian Institution, Washington, DC, by the then owner.

So much for the history of Hope. Its  chemistry  (and also of all natural blue diamonds) is  equally interesting.  Chemists were fascinated by the brilliant blue and embarked on the job of identifying the cause. In 1971  it was established categorically that traces of boron   imparted the  blue colour and not aluminium as was believed till then.  It was also seen that  boron would  impart blue colour, only in the absence of other impurities. Hope diamond  underwent a systematic, rigorous  scientific grading by the Gemological  Institute of America (GIA)  in 1988.    Non-destructive spectroscopic techniques such as Infrared, Ultraviolet and  Pulsed luminescence were used to estimate the boron content.  Hope recorded  a value of 0.6 ppm boron (parts per million). Diamonds are in general insulators, but natural blue diamonds are p-type semi-conductors.  Because trivalent boron in  a  lattice work of tetravalent carbon leaves vacant slots, i.e. holes which facilitate electron jumping.    

While chemistry was thus explained, geochemistry still remained elusive for a long time. Because  boron is available only in the continental and oceanic crust which run to   an average  depth  of roughly 65 kilometres only.  Whereas diamonds are known to be formed at a depth of 100-250 kilometres, in the upper mantle. Several studies alluded to an even deeper zone, a depth of 660 kilometres, for blue diamond formation.  So how did boron travel so far  down?  Perhaps we have an answer now. "Geological pathway for recycling of Earth's surface materials  into the mantle are both driven and obscured by palte tectonics" contend  Smith et al  in the August 2nd issue of Nature Magazine.  When continental crust slides over the  oceanic crust, lithosphere rich in rocks and minerals  gets  pushed down through serpentine pathways  into the lower mantle. 

Geological process of subduction: Courtsey wikipedia                                                                                                                                                    Author: K. D. Schroeder Subduction-en.svg from Wikimedia Commons                                                                                                                                  License:Creative Commons Attribution-ShareAlike 4.0




References:


4. Blue boron-bearing diamonds from Earth's lower mantle : Smith et al Nature 560, 84-`87, 2018



Tuesday, July 31, 2018

Notes from around the World.

According to Global Forest Watch, 16 million hectares of tropical forests have  disappeared in 2017 alone.   Anthropogenic activities are the major  causes  for this green cover loss.    For example  take the case of Colombia.  Situated in  the north western corner of the South American continent, Colombia  ranks high among megadiverse countries. According to the Convention on Biological Diversity website,   Colombia  ranks first in bird and orchid species' diversity and second in plants, butterflies, freshwater fishes and amphibians. With 314 types of ecosystems, Colombia possesses a rich complexity of ecological, climatic, biological and ecosystem components.  Colombian   President recently asserted that biodiversity is to Colombia what oil is for the Arab countries. 


Cocora Valley, Colombia:
Courtesy: wikipedia
But ever since the  ultraleft guerrillas, the FARC, (Revolutionary Armed Forces of Colombia), signed the  peace treaty with the Colombian govt.  and vacated the valleys and  forests (which were their habitat for 50+ years) Colombia's  ecological wealth has been fast disappearing. Because  urban developers want to clear the forests to set up housing, industrial and commercial projects and  of course  timber is  a source of easy money. 



MS Explorer sank in Antarctica 
in 2007 after hitting an iceberg
Courtesy: wikipedia
An equally disturbing   situation is unfolding in Antarctica . The Antarctica Treaty was initiated  in 1959 with 12 nations.  Later this number grew to  53. According to the Environmental Protocol the participating countries committed themselves to protect and cherish the ecosystem and use it only for science and peace.  All the  signatories  were on the same page while signing, but no longer so. Geopolitics is threatening the pristine continent because of  speculations on  the continent's stock of fish and  minerals as every nation wants a share.   Recent reports state  that in  Ile aux Cochons, an Antarctica island,  penguin population has declined by 90% in a span of 3 decades for reasons as yet unknown.   
               Deepwater Horizon Disaster                      
Courtsey: wikipedia

Meanwhile the United States has  relaxed its Ocean Policy.  Earlier  administration had put stringent restrictions on offshore activities  after the 2010 Deepwater Horizon  Disaster  in the gulf of Mexico.   That disaster,  an explosion  in the deep sea  oil rig, caused  134 million gallons of crude oil to spew out into the Gulf of Mexico causing environmental damages to the tune of   17.2 billion dollars. This damage has not yet been contained nevertheless   US Govt. has decided to revoke the restrictions and   promote offshore drilling for gas and oil  over approximately 78 million acres offshore. The region-wide lease sale  is scheduled for Aug. 15, 2018. 

We were just 1 billion people in the year 1800 and currently  register 7.6 billion and by 2100 the number will touch 11 billion.  Population challenge is compounded  by shrinking villages and booming urban spaces. 70% of the global population will be city dwellers by 2050.   China, India and Nigeria are expected to lead in this sphere.  Sure enough  anthropogenic activities associated with urbanisation will steadily and rapidly deplete natural resources.  Who should be concerned, Man or Mother Nature?  Nature has been through 5 cataclysmic mass extinctions, it can easily survive one more. Professor Reinhard Huttl at the Helmholtz Institute for Earth and Environment  observes wryly that Earth has enough  generative power to tide over  any disaster, it is us humans who are in danger. 

REFERENCES:

1. Reform the Antarctic Treaty : Nature editorial 14 June 2018,pp161
2. Watch over Antarctic waters: Cassandra Brooks et al,   Nature 14 June 2018 pp177-180 
3. Antarctica: Nature Insight 14 June 2018 pp 199- 241(Several articles)
4. Last King Penguin colony in the world drop by 90%

Friday, June 29, 2018

Magical Realism ? (with apologies to García Márquez)

Looks frosty on the roll, invisible on the job  that is how 3M company  advertises its product, the Magic Tape.  3M  came up with  transparent cellophane sealing tapes in the thirties. If that was a huge success, then   the Magic tape introduced in the  early sixties was indeed a  roaring success.  The convenience of  writing  over the Magic Tape  with a pen or pencil  or marker  increased  its popularity immensely. Today   MT has become  an integral part of every day life for everybody  - children, adults ,artists, executives,  housewives ……… .  3M soon designed  a convenient tape  dispenser too. Besides the magic tape  3M has  a whole series of  tapes in its Scotch portfolio, to suit any need/emergency. Particularly impressive are the colored,  patterned  and glitter  tapes.  The post-it  is also currently available in tape form.  All  these  are tapes which stick onto a surface when you apply a little  pressure( thumb pressure will do) and hence are also called  Pressure SensitiveTapes(PSTs).
       
But try peeling off the  tape,(exclude the post-it ) and you get a tutorial on magical realism. The tape pulls off a layer of the  surface it  is attached to.   Amazingly this worked like magic and   fetched  Andrei Geim and Kostya Novoselov   Nobel Prize in Physics in 2010  for the discovery of graphene.   In fact the Nobel committee made a mention of the playfulness of the scientists and their   process:  Playfulness is one of their hallmarks, one always learns something in the process and, who knows, you may even hit the jackpot. Like now when they, with graphene, write themselves into the annals of science. The  tape dispenser used by Geim and Novoselov   is  currently an exhibit  in the Nobel Museum, Stockholm.

But  reality remains.  Such tapes are used as short term damage control agents  to hold together  heritage materials or artworks.  By the time  authorities get down to  extensive restoration work, the  band-aids are often  discolored and/ or are  irretrievably  stuck to the surface.  Confronted with this  challenge, Professor Baglioni of the department of Chemistry, University of Florence   came up with a unique solution.    He and his team  “addressed the  issue from a physicochemical perspective”.
 
Professor Baglioni and his team  found that the   most popular PSTs used for damage control of artworks are    FilmoplatP (FPP), MagicTape (MT) and ordinary tape(OT).  In all the three  the adhesive is  acrylic based,  while the backing (tape material)  was cellulose for FPP,  cellulose acetate for MT  and  polypropylene for OT.   The team  had to design a peeling process restricted to the surface area of the tape  so that surrounding areas remained unaffected.  They solubilized a mixture of assorted organic solvents  in  water  using a detergent called  sodium dodecyl sulfate . The detergent ensured that the organic solvent mixture remained as nanosized droplet in the aqueous medium. Hydrogels, which are polymeric scaffolds with high affinity for water,  when immersed  in this medium,  absorbed  the same.    The swollen hydrogel was cut into strips of  required size and    applied over  the tapes. The solvents  slowly penetrated the backing  and in less than  half an hour  the tape could be easily pealed off.  
References

  1. Scotch Products for consumers
  2. Nobel Prize for Physics 2010
  3. Restoration of paper artworks with microemulsions confined in hydrogels for safe and efficient removal of adhesive tapes