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Mumbai Monday, 9 April, 2018 - 08:17

Scientists from IITB show how using drugs in combination can help treating tuberculosis caused by drug resistant bacteria.

The fact that Mycobacterium tuberculosis, the bacterium that causes the deadly tuberculosis, has developed resistance to most of the antibiotics we have today, is not news anymore. Many bacteria are developing resistance to common antibiotics faster than the number of effective drugs being discovered to fight them. The need of the hour is not just a “new” drug, but possibly a new method of treatment that can fight drug resistant bacteria. Now, a study by Prof. Sarika Mehra  and her team from Indian Institute of Technology Bombay (IITB) has uncovered a mechanism to increase the efficacy of the commonly used antibiotic rifampicin.

But, how did these bacteria become resistant to the same drug that once killed them? Our irregular and improper use of antibiotics is to be blamed. Due to intermittent exposure to these drugs without completion of an antibiotic course, many bacteria have evolved mechanisms to survive in the presence of these antibiotics. Now, they have turned fatal; multi-drug resistant tuberculosis was responsible for 2,50,000 deaths worldwide and 4,80,00 new cases of tuberculosis in 2015 alone!

In this study, published in the journal Frontiers in Microbiology, the scientists have improved the efficacy of rifampicin by delivering it with another active compound called cumene hydroperoxide (CHP). “The current regime against tuberculosis involves combination therapy of drugs, which works fine in eradicating drug-sensitive Mycobacteria. However, many of the existing drugs are ineffective against the widespread drug-resistant strains of Mycobacterium”, says Prof. Mehra, who headed the study. “A major focus of our research is to find alternate ways of targeting resistant bacteria by use of an adjuvant---a compound that by itself might not have antibiotic properties, but can enhance the efficacy of existing anti-TB drugs”, she adds.

The researchers used cumene hydroperoxide, an oxidizing agent, as it induces ‘oxidative stress’ in the bacterial cell. Oxidative stress is the disruption of the balance between free radicals (atoms with unpaired electrons) and antioxidants that neutralise them. “Under oxidative stress, many free radicals are generated and they can attack the various constituents of the cell such as the DNA.”, explains Prof. Mehra.

To save themselves from oxidative stress, the bacteria destroy these harmful free radicals by converting them to their non-radical form using enzymes. However, if the volume of radicals is much more than what can be neutralized by the cell’s enzymes, the radicals start attacking the components of the bacterial cell itself. The researchers have exploited this mechanism by increasing the production of free radicals using cumene hydroperoxide, which targets the cell membrane, leading the cell to rupture and death.

The researchers tested their combination of drugs on Mycobacterium smegmatis and Mycobacterium bovis BCG, close cousins of the TB bacteria. They subjected these bacteria to various combinations of the antibiotic rifampicin, and the oxidising agent cumene hydroperoxide, in different doses. They found that if used in combination with cumene hydroperoxide, the Rifampicin dose required was 16 times less than an individual dose of the antibiotic. Individually, a minimum dosage of 32 microgram(μg)/ml (equivalent to a pinch in a bucketful of liquid) of rifampicin, or 380 μg/ml of cumene hydroperoxide, was required to inhibit bacterial growth. But, when given in combination, minute amounts of rifampicin and a lesser than half the dose of cumene hydroperoxide, had the same effect. Further, a drug-resistant strain that needed high dose of rifampicin for growth inhibition, could now be inhibited by a lower dose of rifampicin in combination with of cumene hydroperoxide.

So, how did the combination of drugs act on the bacteria? In most cases, treating infections with antibiotics, including rifampicin, has one major issue -- the amount of drug that the bacterial cells absorb is very less. More the drug absorbed, better is the efficacy. In this study, the researchers observed that in the presence of cumene hydroperoxide, rifampicin was readily taken in by the cells. Once inside, rifampicin prevents the production of enzymes which neutralize the free radicals. The free radicals thus produced caused oxidative stress in the bacterial cells and resulted in the death of these cells.

Using the drugs in combination enabled using smaller drug dose. This is of significance, since this reduces the risk of side effects. “The effect of radical species on healthy human cells is similar to that on bacterial cells. It may cause damage to DNA and various cell components and increase the risk of diseases such as cancer and Alzhiemer”, explains Prof. Mehra.

In the backdrop of evolving ‘superbugs’, the study definitely holds hope in countering them. “As the data obtained so far is very promising, we will next extend this to Mycobacterium tuberculosis strains in collaboration with a lab used for research on dangerous biological agents and organisms”, says Prof. Mehra on the future direction of this research.

Section: General, Science, Health, Deep-dive Source:
Nagpur Friday, 6 April, 2018 - 16:08

Scientist from Visvesvaraya National Institute of Technology, Nagpur, National Institute for Material Sciences, Ibaraki, Japan and Institute for Plasma Research, Gujarat have developed a novel composite material composed of carbon nanotubes decorated with thin films of zinc ferrite (ZnFe2O4) for practical applications like, energy storage.

Supercapacitors are devices that store a large amount of energy in an electric field between the plates of two electrical conductors. Supercapacitors are called so due to higher amounts of energy storage capacity, compared to conventional capacitors. Recently, thin film supercapacitors have gained much prominence, due to their small volume and high energy and power densities. This makes thin film supercapacitors efficient components while developing energy storage solutions.

In their recent study, the scientists built high performance supercapacitor using thin film zinc ferrite anchored on multiwalled carbon nanotubes (CNT)—where carbon molecules are arranged in a cylindrical nanostructure, much like a rolled up sheets of carbon molecules. The scientists used successive ionic layer adsorption and reaction (SILAR) method to build the thin films anchored on CNT. Here successive atomic layers of zinc ferrite are deposited on the carbon nanotube cylinders, one at a time, to form the complete structure. According to the authors “This is a simple and inexpensive method which has the advantage of direct electrode formation without the use of any binder”. This helps bring down the overall cost of manufacturing the devices, while also enabling easier scaling of the manufacturing process.

The composite electrode (ZnFe2O4-CNT) thus formed yields a high specific capacity of 217 mAh g–1 at 5 mV s–1, making it a suitable candidate for high performance supercapacitor applications. The scientists believe this high specific capacity is formed by contributions from the inner and outer active surfaces of the hybrid ZnFe2O4–CNT electrode. The device also demonstrated the highest specific energy and specific power, when compared to conventional supercapacitors.

“This clearly demonstrates that our hybrid ZnFe2O4–CNT electrode is promising and innovative for energy‐storage applications” exclaim the scientists about their latest offering.

Section: General, Science, Engineering, News Source: Link
Bengaluru Friday, 6 April, 2018 - 07:44

The Golden age of antibiotics was an era spanning from 1950 to 1960, during which most common antibiotics like Penicillin, Streptomycin, and Chloramphenicol were discovered. These antibiotics were considered to be 'silver bullets' that would soon eliminate all bacterial infections. Unfortunately, bacteria proved to be extremely resilient, and resistance to these drugs quickly emerged. Today, bacterial pathogens resistant to nearly all antibiotics threaten to undo decades of medical progress. The indiscriminate use of antibiotics for the treatment of common infections and in the food industry  have  exacerbated the problem,  giving rise to new drug-resistant pathogens worldwide. Hence, researchers from around the world are compelled to discover better antibiotics to kill some of the most potent drug-resistant bacteria. In one such attempt, researchers from the Indian Institute of Science, Bengaluru, led by Prof. Nagasuma Chandra, have used a computational approach to design and synthesise amino acid polymers called peptides, which are highly effective in killing an array of multi-drug resistant bacteria.

Hundreds of such peptides, commonly called as 'antimicrobial peptides' (AMPs), that fight against invading bacteria, are found in multicellular organisms, including humans. The researchers of this study, published in Journal of Biological Chemistry, used a machine learning algorithm that studied the sequences of thousands of such peptides.  They deciphered the common patterns unique to those peptides.  As an analogy, a meaningfully constructed sentence inherently uses a framework of rules that can be considered as its grammar.  The researchers looked for such a 'grammar' in the sequences of these antimicrobial peptides.

“Protein sequences remarkably are similar in structure to language, where complex rules about syntax and grammar help define the semantics (or meaning) of a sentence", says Deepesh Nagarajan, from the Department of Biochemistry, IISc, the first author of the study.  To reveal this hidden grammar, the researchers used a neural network-based algorithm called Long short-term memory (LSTM). “LSTMs have a kind of ‘memory’ that allows it to retain information for 1000s of time-steps, which is very useful for   tasks such as speech-recognition and language processing”, remarks   Tushar Nagarajan who wrote the algorithm.

The researchers trained their algorithm by feeding it with thousands of unique peptide sequences that were known to possess antimicrobial properties. The training helped the algorithm to analyse and learn. “We had thousands of peptide sequences to analyse, whereas, at the time of previous work, only hundreds of antimicrobial peptides were characterised”, says Deepesh, commenting on the success of the prediction. The program then predicted several thousand candidates that had potential antimicrobial activity.

A few antimicrobial peptides were synthesized and found to possess activity against a variety of common pathogens. The best peptides were found to inhibit multi-drug resistant pathogens resistant to drugs of last resort like meticillin and carbapenem antibiotics. Further, one of the peptides tested was able to decrease the bacterial load of drug-resistant Acinetobacter baumannii a hundred-fold in 4.5 hours, in a mouse model of infection.

So how did the peptides act on bacteria? "We discovered that the peptides bound to and disrupted the bacterial cell membrane" says Prof. Disphikha Chakravortty, an author of the study. Peering through an electron microscope, they saw that the cylindrical bacteria had become ridged and flattened after being treated with the peptides. The bacteria were seen bleeding out cytoplasm through the holes created by the peptide binding. Since the entire cell membrane is targeted, the researchers believe that the bacteria will never be able to develop resistance against it.

“By targeting and disrupting the entire cell membrane, we simultaneously target a variety of lipid molecules, membrane proteins, and ion channels. The pathogen has to simultaneously evolve changes in all these molecules to develop resistance, which is much more difficult to accomplish via random mutations”, says Nagasuma Chandra.

This path-breaking study succeeds at developing drugs that target the bacterial cell as a whole, rather than focus on a single molecule within the cell. Since drug-resistant bacteria are quick to evolve, any bacterium in the community with a slightly different version of the targeted molecule has the potential to survive and thrive. The peptide molecule, developed by the researchers causes irreparable damage on a scale that the bacterium cannot recuperate, let alone develop resistance!

Section: General, Science, Health, Deep-dive Source:
Kanpur Thursday, 5 April, 2018 - 16:07

Scientist from Indian Institute of Technology Kanpur (IITK) have developed a novel ternary nanocomposite (compound made of three different nano compounds) which can remove methylene blue from a solution when shone with visible or Ultra Violet (UV) light.

Methylene blue, also known as methylthioninium chloride is a well known medicinal compound that has been in use for over a century. It has been commonly used to treat urinary tract infections, cyanide poisoning and methemoglobinemia, a type of disease which increases the levels of certain type of haemoglobin in the blood. Methylene Blue is also used as a dye in procedures like chemoendoscopy to test the urinary tract for leaks and fistulas.

However, methylene blue is also known to cause severe side effects like hypertension, fever, dizziness, nausea and vomiting. When doses larger than 5 mg/kg are injected, the compound is also known to cause bladder irritation and anemia. This makes it important to remove excess of methylene blue from the body and other other sources, like drinking water.

In their new study, the scientists formulated a ternary nanocomposite based on titanium dioxide, ferric oxide and reduced graphene oxide (rGO-Fe3O4-TiO2) for degradation of methylene blue under visible or UV light. The nanocomposite, when illuminated with visible or UV light undergoes a process called separation of charge carriers, wherein electrons from TiO2 move to rGO, thus initiating another process called photo-Fenton reaction, which provides highly reactive hydroxyl ions which mineralizes the methylene blue in solution. The nanocomposite was prepared using a wet-assembly method with varying weight ratio of each of the components to arrive at a suitable weight ratio for efficient degradation of  methylene blue.

The study has revealed the rGO-Fe3O4-TiO2 nanocomposite having composition 1:1:2 has achieved maximum degradation of methylene blue from the aqueous solution. It also showed that About 99% of the dye has been removed within 6 min under UV irradiation, while in presence of visible light, 94% has been degraded from the wastewater.

According to scientists “these results indicate that these ternary nanocomposites possess great potential for both UV and visible light driven methylene blue destruction from the wastewater”.
 

Section: General, Science, Technology, News Source: Link
Bengaluru Thursday, 5 April, 2018 - 07:50

Ask a rice grain, “where are you from and what’s the climate like there?” and it will answer you. Yes, the humble rice we eat every day can be a climate historian, says a new study by researchers from the Indian Institute of Science (IISc), Bangalore. In a first of its kind attempt, they have demonstrated the potential of rice grains as recorders of relative humidity—the amount of water vapour in the air, and the changes in monsoon.

“Understanding the long-term variability of the southwest monsoon over India is a key scientific question to our modern society. Like today, rice cultivation since the Harappan civilisation depended on monsoonal rains.  Hence, rice can confirm monsoonal variability in the past”, says Dr. Ritika Kaushal, Research Associate at the Centre for Earth Sciences, IISc and one of the authors of the study published in the Journal of Geophysical Research: Biogeosciences.

The study proposes a linear relationship between the stable isotope composition of oxygen and carbon in rice grains, with relative humidity. Isotopes are atoms of the same element that have the same number of protons and electrons but differ in the number of neutrons. There are two stable isotopes of carbon and two for oxygen that were used in this context. The proposed relationship can help in understanding the climate parameters prevalent when the rice was grown.

“The present study explores the potential of rice grains to serve as recorders of climate. Application of the study might give us clues on the climate prevalent during Harappan civilisation and the factors that might have contributed to its eventual collapse around 3,000 years before present”, say the authors while talking about their study.

The researchers collected 105 varieties of rice grains from 23 different locations across India grown during the rainy seasons, from 2010 to 2014.  The study sites ranged from Jammu to Andaman and Nicobar Islands and lay in different climatic zones. They then studied the oxygen and carbon isotopes in the rice grain, which depend on the relative humidity in the atmosphere and the water that was used to cultivate.

Further, the researchers calculated an ‘enrichment parameter’, which is the adjusted value of oxygen isotope after removing the contribution from source water.  This parameter was found to be strongly dependent on the relative humidity, implying that as the humidity increased, the enrichment of oxygen in the rice grain decreases. The researchers have proposed the linear equation based on this dependence.

Similarly, the researchers calculated a ‘discrimination parameter’ for carbon isotopes in rice grains by removing the effect from atmospheric carbon dioxide, and established its relationship with relative humidity.  The results prove the influence of relative humidity as a driver of variations in both oxygen and carbon isotopic composition.

The researchers claim that besides understanding the past climate, the results can also help in the authentication of rice grains. “Food authentication involves proving the geographic origin of the food, which is important for food safety, food quality, and consumer protection. For instance, basmati rice is a geographical indication denoting a particular type of rice from the foothills of the Himalayas. The properties yielding high market value for basmati can be attributed to the geographical origin and the prevalent conditions. Not surprisingly, there is an alarming number of adulteration cases, especially by the exporters. The present study provides the geographic characterisation of the most commonly cultivated rice varieties in India, including a few basmati varieties and presents an index for rice-grain authentication”, explains Dr. Kaushal.

The study has demonstrated that one can derive climatic information of the past using well-preserved rice grains from archaeological sites. Considering that ours is a monsoon dependent country, these findings help us understand the long-term variability of the southwest monsoon. The results could also help us identify climate-resilient rice varieties for uncertain climate scenarios of the future.

Extending the study, the researchers also wish to get wheat talking!  They plan to understand the dependency of wheat on the climate parameters. As the grain is cultivated in India during winter, one could use wheat as a recorder of winter monsoons.

Section: General, Science, Deep-dive Source:
Delhi Wednesday, 4 April, 2018 - 16:07

A new study by scientists at Council for Scientific and Industrial Research (CSIR) - Institute of Genomics and Integrative Biology and All India Institute of Medical Sciences in New Delhi have identified the potential role of two genes--ARID1A and KAT2B in the development of obesity.

Obesity or overweight is defined by the World Health Organization as having a Body Mass Index of over 30 Kg/m2. A WHO survey in 2015 of 195 countries identified over 600 million adults and around 100 million children as obese or overweight. The increased body weight is known to cause several health conditions including, cardiovascular diseases, diabetes and even some cancers.

Conventionally, the reasons identified for obesity was intake of energy-dense foods that are high in fat, salt and sugars and a decrease in physical activities. However, recent studies have shown a strong genetic basis for obesity and that certain populations have a stronger genetic predisposition to obesity compared to other populations 1.   

In their new study, the scientists set out to study and identify the genes associated with obesity and overweight. 3,530 adolescent (age 11-17) participants were selected for the study, of which 2,539 were of normal weight and 991 were grouped under overweight/obese category. All the participants were from an Indian-European origin and were selected from school health surveys, from different parts of Delhi.

According to the study, obesity involves alterations in gene expressions that can change in response to genetic and environmental signals through chromatin modifications. Chromatin is a complex macromolecule containing DNA, proteins and RNA, and plays an important role in gene expression and DNA replication, preventing DNA damage and packaging the DNA in to a dense, compact shape. The scientists hypothesized that “genetic variations in chromatin modifier genes can predispose to obesity”

Further, the study identified two variants namely; rs6598860 and rs4589135 of the ARID1A gene having significant association with overweight/ obesity. It also revealed the association of the variant rs3804562 of the KAT2B gene with BMI.  

According to the researchers “our data revealed that common variants of ARID1A and KAT2B are associated with increased susceptibility to overweight/obesity in Indian urban adolescents and provides a lead for future investigations toward understanding the contribution of epigenetic modifiers in genetic predisposition to obesity in adolescents”

Section: General, Science, Health, News Source: Link
Kanpur Wednesday, 4 April, 2018 - 07:34

Our brain, the seat of our personalities, memories and emotions, is arguably the most critical organ in our body. If a cancerous tumour grew in our brain, it might impair its functions, and the results would be catastrophic. While chemotherapeutic drugs are used to combat cancer, these drugs also damage healthy cells, restricting their growth and reproduction. In an attempt to make chemotherapy safer, researchers at the Indian Institute of Technology Kanpur have proposed a new model for the transport of anti-cancer drugs to human brain tumours using liposomes—a small sac-like structure that transports nutrients in our cells.

Liposomes, like our cell membranes, are made of molecules called phospholipids. In a cell membrane, these molecules are arranged into two layers. However, in a liposome, the two layers meet to form a hollow sphere filled with water. In this study, the researchers propose to replace the water in the empty area with anti-cancer drug molecules—a technique they claim improves transport of the drug molecules—to create a nanosized drug delivery system.

Besides, the lipid layer in the liposomes acts as a protective coat and prevents the anti-cancer drug from affecting healthy cells. Since these liposomes are in the bloodstream, they circulate for longer and collect at the tumour site, helping more of the drug reach their target cells. This approach causes less damage to the healthy cells of the body.

“Liposome-encapsulated drugs are widely used to cure cancer because of their prolonged circulation time in blood plasma and better efficacy as compared to free chemotherapeutic drugs”, says Dr. Ajay Bhandari, a research scholar at IIT Kanpur and an author of this study, published in Journal of Biomechanical Engineering. “DOXIL, a type of liposome encapsulated drug that has been widely used to treat different types of human tumours, has been beneficial towards improving chemotherapeutic drugs, making them more efficient and safer to use”, he adds.

There is another aspect of tumours that makes it hard to use anti-cancer drugs in treatment without damaging the surrounding healthy cells. Tumorous cancer cells vary in their organisation, function and structure, making it difficult for drugs to target them specifically.  Also, the veins and arteries that supply blood to a tumour, twist and coil, making it more difficult to administer the anti-cancer drug into a tumour. Since the endothelial cells present in the tumour blood vessels are widely spaced out, drugs tend to leak out into the interstitial spaces between the cells, reducing the efficacy of the drugs.

“Liposome-encapsulated drugs can accumulate at the tumour site better than a free chemotherapeutic drug because they can circulate in human blood plasma for a longer amount of time. The drug DOXIL, used for simulation in our current study, does not get cleared out from the human body easily. Also, since liposome-based anti-cancer drugs have a higher concentration in the blood plasma, they tend to have a higher concentration in the interstitial space, thus killing more tumour cells”, says Dr. Bhandari, talking about the proposed drug-delivery technique.

The researchers analysed the structure of blood vessels of the cancerous brain tissue using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) by taking multiple snapshots of the tumor vasculature over a period of time and comparing them. Using this data, they predicted the transport, accumulation and efficacy of the chemotherapeutic drug in a tumour with computational fluid dynamics—a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyse problems that involve fluid flows. They also predicted the distribution of the drug in a tumour. “With the help of this model, we can predict the preferential deposition of chemotherapeutic drugs inside a tumour, thus predicting the healing of a tumour for a specific patient, provided we have the initial medical images of that patient”, says Dr. Bhandari.

The results of the study showed that a high amount of the anti-cancer drug Doxorubicin, which was not encapsulated by a liposome, accumulated in the interstitial spaces between tumour cells. This accumulation could potentially cause adverse side-effects like swelling, reddening and peeling of skin from the hands and feet. In contrast, the liposome-encapsulated drug remained inside a tumour for a longer time. They also found that the high concentration of liposome-coated drug aggregated at the tumour site and increased the therapeutic efficiency of the liposomal anticancer drug.

Medical imaging of the tumours helps predict the deposition of the anti-cancer drug in a tumour for a patient and look for chemotherapeutic drug options that could better suit him/her. This ability also allows doctors to develop a specific chemotherapeutic approach for each patient, based on the structure of their brain tumour and the blood vessels surrounding it.

The researchers hope that medical imaging, combined with numerical models, can help cancer patients better by reducing the adverse side-effects seen with many drugs. “To this end, numerical modelling is an excellent non-invasive tool to understand the complexity that is involved in the transport of anti-cancer drug”, says Dr. Bhandari, talking about the importance of the research.

Section: General, Science, Technology, Health, Deep-dive Source:
New Delhi Tuesday, 3 April, 2018 - 18:44

Indian Institute of Science (IISc), Bengaluru has for the third consecutive year, bagged the top rank in the National Institutional Ranking Framework (NIRF) which was announced by the Minister of Human Resource Development, Shri. Prakash Javadekar on 03 March 2018.

The institutions are ranked by NIRF based on five broad parameters, namely; Teaching, Learning and Resources (TLR), Research and Professional Practices (RPC), Graduation Outcomes (GO), Outreach and Inclusivity (OI) and Perception (PR). The five parameters with a ranking weightage given to each are then used to arrive at an overall ranking for the institutions.

Of the 100 institutions that were ranked, IISc secured an overall top score of 82.16 to bag first rank, while Indian Institute of Technology Madras, Chennai with a score of 81.39 bagged second rank and Indian Institute of Technology Bombay, Mumbai ranked third with an overall score of 79.20. Indian Institute of Technology Delhi, New Delhi, Indian Institute of Technology Kharagpur, Kharagpur, Jawaharlal Nehru University, New Delhi, Indian Institute of Technology Kanpur, Kanpur, Indian Institute of Technology Roorkee, Roorkee, and Banaras Hindu University, Varanasi were the other universities to make it to the top 10.

While the ranks of many top universities remained unchanged, Anna University, Chennai which was ranked 13 last year climbed three spots to rank 10 this year, while IIT Guwahati which held the 8th rank last year slipped to rank 12 in 2018.

While IISc topped the scoring in three of the five parameters, namely; TLR, RPC and PR, Jawahralal Nehru University scored the highest in the GO and OI parameters. Goa University, Goa, Cochin University of Science and Technology, Cochin and Delhi Technological University, New Delhi scored the lowest to rank 98, 99 and 100 respectively.

Four Institutions, namely: ICAR - National Dairy Research Institute, Karnal, Indian Agricultural Research Institute, New Delhi, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru and Tata Institute of Fundamental Research, Mumbai were also given special mention by NIRF for the year 2018. 

NIRF was approved and launched by the Minister of Human Resource Development (MHRD) in 2015 and outlines a methodology to rank institutions across the country. A core committee set up by the MHRD identifies broad parameters for ranking the various universities and institutions in the country. 

Section: General, Science, Technology, Engineering, Policy, News Source:
Mumbai Tuesday, 3 April, 2018 - 16:38

Using space-borne remote sensing instruments, scientists from Indian Institute of Technology Bombay (IITB) have detected evidence for hydrous and hydrated minerals on the Martian surface. An excess of such minerals were found associated with impact craters on Mars and could be a result of either pre-existing ancient hydrothermal systems or hydrothermal systems that were created due to the impact by meteors, asteroids and comets.

Hydrous and hydrated mineral are those which have undergone changes to their crystal structure due to the addition of water. The presence of such mineral often points to presence of liquid water or hydrothermal systems driven by fluids and varying temperature.

In their study, the researchers focussed on impact induced hydrothermalism or hydrothermal systems that could have originated due to an impact. They detected and mapped the hydrous and hydrated minerals using orbital imaging spectroscopic, high-resolution panchromatic and digital elevation data. They also found craters with evidence for impact-induced hydrothermalism on the red-planet.

The study identified mineral assemblages of phyllosilicates such as smectites, kaolinites, prehnites, chlorites, and mica, and some tectosilicates such as hydrated silica. The most common minerals found were chlorites, Fe/Mg smectites, with a few instances of prehnite, which the researchers attribute to sub-surface alteration.  Aluminium phyllosilicates were also commonly observed, suggesting near-surface liquid water activity for extended periods. 

Using the data obtained from the hydrated minerals and the hydrothermal alterations, the researchers could further probe the nature of the circulating hydrothermal fluids, including the fluid to rock ratio and its pH.  The researchers could also not identify any spatial patterns in the distribution of these minerals. They believe that these impact-induced hydrothermal systems may suggest local events, which are limited within individual craters. 

Apart from adding more evidence to the theory of liquid water having existed on the Martian surface, the study also identifies the role of imaging spectroscopy and space based remote sensing in identifying hydrated and hydrous minerals on the red planet.

Section: General, Science, News Source:
Pune Tuesday, 3 April, 2018 - 07:53

Egyptian fruit bats are nocturnal, fruit eating bats that are found in Africa and parts of Asia. Like many of their other closely related cousins (species), they use high-frequency sound waves to navigate and find their food. But there is one aspect of the Egyptian fruit bats (Rousettus aegyptiacus) that has baffled scientists until now. While most bats move their heads, nose, ears or mouth to change the direction of the sound waves they produce, these bats do so without any visible movements in their head or body. Now, a study by researchers from the University of Washington, USA, Johns Hopkins University, USA and the Indian Institute of Science Education and Research (IISER) Pune, has revealed how these bats may use their tongues to change the direction of sound waves.

Among the 1300 species of bats found in the world today, about half of them ‘see’ using sound waves through a behavior called echolocation. Echolocating bats send a high-frequency sound wave in a sonar beam towards objects and listen to the returning echoes. The returned echoes give them a glimpse of their surroundings, much like a flashlight illuminating a section in the dark. They also change the direction of these sound waves to scan different parts of their surroundings. Some bats, including the Egyptian fruit bat, produce sharp clicks with their tongue to generate the sound waves, while other bats produce longer calls from their larynx.

Previous studies have shown that Egyptian fruit bats emit clicks in pairs, alternating towards the left and right directions and within as quick as 20 millisecond. The click directions can point to as large as 60 degrees apart. In the present study, published in the journal PLOS Biology, the researchers found evidence suggesting that the beam direction is changed by changing only the position of the tongue. The researchers hypothesised that the bats move their tongues to generate rapid alternation of click directions. Although similar mechanisms had been suggested for other species of bats, none were experimentally tested for any bat species prior to this research.

The researchers of this study conducted various experiments on three Egyptian fruit bats to unravel the mystery. “The bats were acquired from the wild in Israel”, shares Dr. Anand Krishnan, one of the researchers of the study from IISER Pune. “They're quite easy to rear. The bats are wary of people at first, but become very tame and gentle with training and handling. After that, they can even be trained to perform several behavioural tasks”, he adds, explaining how the researchers conducted their study.

During the experiments, the researchers released the bats from a podium. While the bats were flying, they used 10 high-speed motion capture cameras to measure the bats’ head movement. They also measured the echolocating clicks using ultrasonic microphones. They then reconstructed the bat’s sonar beam using the microphone recordings and its head and overall movements using reflective markers placed on the bat’s head. Through modelling and three-dimensional computations, the sonar beam patterns were also studied.

The researchers found that their hypothesis was supported by the experimental observation. This study presents the first evidence that the direction of sonar beam can be changed by moving the tongue, which causes changes in phase difference across a series of sound sources located along the side of the bat’s mouth. Dr. Krishnan calls it, “a remarkable coincidence of engineering design and biological principles”, as the bat’s mechanism is broadly similar to human engineered phase arrays that allow steering of a beam of radio waves in different directions without moving the antennae.

‘Bio-inspired’ designs help us to create and improve technologies by choosing and applying the best principles from nature. The researchers say that this study might serve as an example where our inventions could have helped understand nature better. “Although many biological discoveries have led to engineering innovation, this study is an important step in using human engineering design principles to elucidate fundamental biological concepts”, Dr. Krishnan opines. “The inspiration goes both ways. We will be able to learn important engineering principles from nature such as figuring out the adaptive strategy for sensing the ever-changing environment, and also potentially combine a variety of sensory mechanisms, the way animals naturally do”, adds Dr. Wu-Jung Lee from University of Washington, who is also a the corresponding author of the study.

Section: General, Science, Deep-dive Source:

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