Current Affairs for IAS Exams - 22 August 2013

A leap forward in ‘flow’ batteries

• The sources of power in the emerging renewable energy economy are intermittent.

• Wind energy is dependent on winds that are often capricious, and solar power is suboptimal on cloudy days. Such sources cannot be connected directly to the grid but instead to batteries which store power from them and then discharge continuously.

• To better make use of renewable sources of power, these batteries must have a higher power density than normal batteries and must be very efficient.
• Existing options are competent, and scientists are continuously innovating to make them even better.
• Conventional batteries include a porous membrane between the anode and the cathode to prevent short-circuits while facilitating charge-carrying ions to move between them.
• However, such membranes add to the battery’s weight, reduce its efficiency and, depending on their material, bring along their share of structural defects and life-cycle limitations.
• Through this channel, the group pumped liquid bromine over a graphite cathode and hydrobromic acid under a porous anode, while flowing hydrogen gas across the anode.
• Thus, a “natural” membrane is formed between the anode and cathode while still keeping the ion-transfer channel option.
• Hydrogen and bromine react with the electrodes to store energy or release it via an external circuit. The paper notes that a voltage transfer efficiency of 92 per cent was measured at 25 per cent of peak power.

Knocking down the malaria causing parasite

• Targeting the malaria parasite’s ability to make an iron-containing molecule, haem, might help create a vaccine against the disease and also lead to novel drug therapies for blocking infection and transmission, according to research from a team of Indian scientists that was published recently inPLOS Pathogens.

• In the course of its complex life cycle, the parasite is able to access haem when it infects red blood cells and gobbles up the haemoglobin those cells contain.
• Haemoglobin is the molecule that makes it possible for red cells to transport oxygen around the body.
• Now, experiments carried out by a team of scientists at the IISc and the National Institute of Malaria Research have shown that having the capability to synthesise haem was “absolutely essential” for the parasite’s development in mosquitoes as well as in early stages of infection when it invades the liver.
• When the single-celled parasite consumes haemoglobin found in red cells, the large amounts of haem generated as a consequence is toxic to the organism.
• It overcomes the problem by turning haem into an insoluble pigment, haemozoin.
• However, the parasite needs haem for iron-containing proteins, known as cytochromes, that are essential for its own energy production.
• “The question arises whether the parasite depends on de novo haem biosynthesis or haem from haemoglobin or a combination of both to make mitochondrial cytochromes,” the scientists turned to Plasmodium berghei , a malaria parasite that infects mice.
• The P. berghei was genetically modified so that two genes for enzymes the parasite required to synthesise haem were knocked out.
• The scientists were able to show that while much of the haem from haemoglobin breakdown ended up as haemozoin, some of it was also incorporated into the parasite's cytochromes.

• Then, through experiments using the human malaria parasite, Plasmodium falciparum, they found that haem synthesised by the parasite while it was in red cells went into cytochromes as well as the haemozoin pigment.

• It may be that the ability of synthesise haem was critical to the parasite in situations where it could not get access to the host's haem, such as when an infected individual had sickle cell anaemia,

Now, blood tests can reveal suicide risk

• Across the world, one million people commit suicide every year.
• Now, a simple blood test that looks for enhanced expression of a few genes can quite accurately identify people who are at great risk of committing suicide.
• Since people planning to commit suicide do not always share their intentions with others, a reliable tool that can “assess and track changes in suicide risk” would go a long way in preventing such deaths.
• A team led by Prof. Alexander Niculescu from Indiana University School of Medicine, Indianapolis has found that enhanced expression of four genes can indicate a person’s inclination to commit suicide.
• Their study was recently published in the Molecular Psychiatry journal.
• Seventy-five bipolar individuals were studied to find the genomic biomarkers using blood samples.
• Prior to drawing blood samples at three to six months interval, the subjects completed a questionnaire wherein they revealed their state of mind — suicidal ideation.
• Of the 75 people studied, suicidal ideation (SI) of nine subjects changed from zero to a high score of two and above in the Hamilton Scale for Depression.
• The Hamilton Scale has a range from zero to four.
• The gene expression in the nine people was compared when they had no suicidal thoughts and when it shot up to a high-risk state.
• This helped in identifying the candidate biomarkers.
• To narrow down the number of candidate biomarkers, and to validate the results, the gene expression results from the bipolar group were compared with those of nine males who had committed suicide. “
• Six biomarkers stood out as significant indicators of suicidal ideation.
• By comparing the results with their previous work, the authors found that genetic association evidence of suicidal risk was particularly present in the case of four of the six genes.
• In the case of bipolar subjects, the suicidal tendency may be associated with dysphoric mood (a general feeling of unhappiness), increased psychosis, anxiety and stress.
• Two biomarkers in particular serve as “key state and trait factors” in those with psychotic mood disorders.

• Finally, the results were compared with subsequent and previous hospitalisations from attempted suicide by 42 men with bipolar and 46 with schizophrenia. The four genes were found to serve not only as state markers (immediate risk) but also as trait markers (future risk) in those with bipolar disorder.

Sources: Various News Paper