Researchers discover simple coating technique using tannic acid and iron

first_img Citation: Researchers discover simple coating technique using tannic acid and iron (2013, July 12) retrieved 18 August 2019 from https://phys.org/news/2013-07-simple-coating-technique-tannic-acid.html Microscopy images of FeIII -TA capsules: DIC image (B), AFM image (C), SEM image (D), and TEM image (E). Credit: Science/AAAS (Phys.org) —A team of chemical researchers at the University of Melbourne in Australia has discovered a simple coating technique that uses nothing but tannic acid and iron ions. In their paper published in the journal Science, the team describes how they added tannic acid and iron ions to a water solution which resulted in the spontaneous creation of a thin film. The film, the group report, coats other materials that are put into the mix without the need for coaxing. Tannic acid is one of a number of phenolics—a family of self-assembling biological materials. Others include lignin, found in wood and melanin, found in skin. Tannic acid is of course, found in wine, and has historically been used to tan animal hides. In this new effort, the researchers looked to make use of the material’s natural ability to coat surfaces.When tannic acid is placed in water it tends to coat anything else that is placed in the water, metals, for example, plastics, or even viruses. Seeking to take advantage of that feature, the researchers added iron ions to the mix, and found that the ions stuck to the acid molecules, resulting in the creation of a thin film. Next, the team added other materials to the mix to serve as various substrates and found that the acid-iron films would spontaneously coat each of them. For small particles, the result was the creation of capsules. Perhaps even more importantly, the team found that by altering the pH level of the solution in which the coating resides, the coating would disassociate itself. Other techniques have been developed to create coatings, of course, but none are as simple (just one step) or inexpensive. More information: One-Step Assembly of Coordination Complexes for Versatile Film and Particle Engineering, Science 12 July 2013: Vol. 341 no. 6142 pp. 154-157 DOI: 10.1126/science.1237265ABSTRACTThe development of facile and versatile strategies for thin-film and particle engineering is of immense scientific interest. However, few methods can conformally coat substrates of different composition, size, shape, and structure. We report the one-step coating of various interfaces using coordination complexes of natural polyphenols and Fe(III) ions. Film formation is initiated by the adsorption of the polyphenol and directed by pH-dependent, multivalent coordination bonding. Aqueous deposition is performed on a range of planar as well as inorganic, organic, and biological particle templates, demonstrating an extremely rapid technique for producing structurally diverse, thin films and capsules that can disassemble. The ease, low cost, and scalability of the assembly process, combined with pH responsiveness and negligible cytotoxicity, makes these films potential candidates for biomedical and environmental applications. Play Video demonstration of the assembly of FeIII-tannic acid films on particle templates. Credit: Hirotaka Ejima This new way to create a coating is important as it contributes to ongoing research looking into ways to create and manufacture soft matter for use in medical and life science applications. It’s not difficult to imagine capsules based on those developed by the team in Australia that hold medicine. Such capsules would release their payload only when they arrive at a part of the body that has the right pH level, allowing for targeted treatment. Journal information: Sciencecenter_img PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further © 2013 Phys.org Spinning up antibacterial silver on glasslast_img read more

Gemini Planet Imager captures best photo ever of an exoplanet

first_imgA combined 30-minute GPI image of Beta Pictoris depicts the planet Beta Pictoris b (bright spot) orbiting its star (center), which has been subtracted from the image. Citation: Gemini Planet Imager captures best photo ever of an exoplanet (2014, May 13) retrieved 18 August 2019 from https://phys.org/news/2014-05-gemini-planet-imager-captures-photo.html (Phys.org) —A team of researchers at the Gemini South telescope in Chile, which has recently been retrofitted with the Gemini Planet Imager (GPI) is reporting in Proceedings of the National Academy of Sciences, that they have captured the best photo ever of an exoplanet orbiting its star. The planet, Beta Pictoris b, orbits its sun approximately 63.5 light years from us, and the GPI has allowed for calculating its orbit at 20.5 years. Explore further Taking pictures of exoplanets is difficult, not only because they are so far away, but also because of Earth’s atmosphere and of course because they are near to a star that is much brighter, which tends to overcome the light reflected off its planets. The engineers who designed the GPI used multiple techniques (a field spectrograph that has both low spectral resolution and high spatial resolution and a coronagraph that suppresses diffraction) to mask direct starlight, while simultaneously enhancing the light that is bounced off of nearby planets. The result, the team reports is an instrument capable of producing images of exoplanets that are an order of magnitude higher than any other previous imaging systems. Beta Pictoris b is a gas giant similar in size to Jupiter, though its star is much younger than ours—just 12 million years old. The picture of it was created with an exposure of just one minute, which is a record for an image of an exoplanet—the planet orbits its star just a little closer than does Saturn in our solar system. It was first discovered in 2006 by researchers working with data from the Hubble Space Telescope and verified three years later by researchers at Europe’s VLT. Pictures taken at the time suggested that Beta Pictoris b had to regularly plow through space debris of some sort, causing it to appear murky at times. Beta Pictoris b was chosen as a first test run due to its designation as an easy target. The research team at Gemini South plan to move on to imaging other exoplanets, eventually taking pictures of at least 600 that appear promising. Doing so will help with better understanding orbit times and perhaps help with refining their ages and masses. Length of exoplanet day measured for first timecenter_img More information: First light of the Gemini Planet Imager, Bruce Macintosh, PNAS, DOI: 10.1073/pnas.1304215111AbstractThe Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of 9.0+0.8−0.4 AU near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. The observations give a 4% probability of a transit of the planet in late 2017. © 2014 Phys.org Journal information: Proceedings of the National Academy of Sciences This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

District students steal march over their city counterparts

first_imgKolkata: Students from the districts continued to dominate the merit list of the Higher Secondary Examinations, the results of which were declared on Friday. 71 out of the 80 students whose names figured in this list are from the districts. Another striking feature of this year’s results has been the success of the minority students.As per statistics of the West Bengal Council of Higher Secondary Education, 80 percent of the minority students have passed the examination this year. Also Read – Heavy rain hits traffic, flights”We have taken it up as a challenge to rope in more and more first generation learners in higher secondary level which is the gateway to higher education. We are happy that we are reaching out to more and more of these learners. Chief Minister Mamata Banerjee’s Kanyashree project and merit-based scholarships by the state government has helped us to penetrate deep into the districts,” said Mohua Das, the Council president, and added that as many as 300 Higher Secondary schools in the districts have been upgraded. According to Das, the dropout rate has also come down from 2.4 percent to 1 percent this year. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedGranthan Sengupta of Jalpaiguri Zilla School has come first with 99.2 percent marks. The second position has been bagged by Ritwik Kumar Sahoo (493) of Tamluk Hamilton High School with 98.6 percent. Ritwik had earlier topped from Bengal in NEET with an all-India rank of 13. The third position went to two students while the fourth place has been bagged by six students including Joydeep Bhowmick of Manindra Nath High School in Cooch Behar. Among the OBC-A category, Sariful Islam of Pandua Sasi Bhusan Saha High School in Hooghly came fifth with 97.2 percent marks. East Midnapore which has clinched the top spot in the Madhyamik examination in terms of successful candidates came up with the highest success rate of 91.98 percent. Despite ranking sixth in terms of success rate, Hooghly secured the highest share of 13 merit list holders. The newly created district of Kalimpong followed next with 91.69 percent of students passing the examination. Kolkata ranked fifth registering a pass percentage of 87.68 which is slightly higher than last year’s 87.37. Nine students from the city made it to the merit list. The overall success rate in Higher Secondary examination dipped slightly from 84.20 to 83.75 percent this year. In terms of success rate, boys performed better than girls with the pass percentage slightly increasing from 85.15 to 85.22 percent this year. A total of 21 girls have featured in the top-10 merit list. The success rate for girls slightly decreased from 83.26 to 82.46 percent this year. However, girls have remained almost at par with boys in securing ‘O’ Grade (90-100) with 2,655 boys and 2,593 girls scoring it. A total of 8,04,895 candidates appeared for the exams that were held between March 27 and April 11. The total number of successful candidates have been 6,63,516. The exams registered participation of 53 percent girls which is six percent higher than last year.last_img read more

Antilarvae drive KMC calls highlevel meeting on June 19

first_imgKolkata: The Kolkata Municipal Corporation (KMC) has convened a high-level meeting on June 19 with senior officials of the Centre and the state government as part of the anti-larvae drive.The meeting will be attended by senior officials of Metro Railway, Eastern Railway, BSNL, Kolkata Port Trust, Satyajit Roy Film and Television Institute, state Public Works department. Senior KMC officials of the health department will also be present at the meeting. Also Read – Heavy rain hits traffic, flightsThe civic authorities will discuss in detail the steps taken by these agencies to keep their establishments clean. Senior KMC officials said drives have been conducted in Central and state government establishments, hospitals and educational institutions along with private housing complexes and individual residential buildings to see whether the garbage had been cleared or not or whether the accumulated water has been cleaned. But these drives are not enough and to make anti-larvae campaigns successful, cooperation between the state and Central government establishments are an absolute necessity. The civic officials said used plastic tea cups and bottles, broken furniture kept on rooftops and empty cans serve as potential breeding grounds for mosquitoes. The larvae take seven days to grow into adults and so if drives are conducted twice a week, the mosquito population can easily be checked. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedIt may be mentioned that the KMC has been conducting anti-larvae drives from January as the breeding pattern of the mosquitoes has changed due to global warming. The state Urban Development department has given Rs 4 crore to the KMC to conduct intense campaigns against malaria and dengue.Debashis Biswas, Chief Vector Control Officer of the KMC, said: “Cooperation of people from all walks of life is needed. If the masses and KMC will work hand-in-hand, the number of malaria and dengue cases will fall drastically.”last_img read more

Turkey blast toll mounts to 95

first_imgAt least 95 people were killed in Ankara when bombs set off by two suspected suicide attackers ripped through a crowd of leftist and pro-Kurdish activists at a peace rally, in the deadliest such attack in Turkey’s recent history. The twin blasts that occurred on Saturday, near Ankara’s main train station, ratcheted up tensions ahead of Turkey’s November 1 snap elections which were already soaring amid the government’s offensive on Kurdish militants.Bodies of slain demonstrators were seen strewn across the ground after the explosions, with the banners they had been holding for the “Work, Peace and Democracy” march lying next to them.The attack also left 246 wounded, 48 of whom are in intensive care, according to an updated toll announced by Prime Minister Ahmet Davutoglu’s office. President Recep Tayyip Erdogan denounced what he called a “heinous attack” targeting “our unity and our country’s peace”.Declaring three days of mourning, Davutoglu said there were “strong signs” the attack was carried out by two suicide bombers.last_img read more

Marijuana quashes brains response to reward over time

first_imgThe findings showed that the reward system of the brain has been ‘hijacked’ by the drug and that the users need the drug to feel reward – or that their emotional response has been dampened.Humans are born with an innate drive to engage in behaviours that feel rewarding and give pleasure, but over time marijuana use was associated with a lower response to a monetary reward. “This means that something that would be rewarding to most people was no longer rewarding to them,” said Mary Heitzeg, Neuroscientist and Assistant Professor at the University of Michigan in the US.  Also Read – ‘Playing Jojo was emotionally exhausting’Further, marijuana use was also found to impact the emotional functioning of the brain. Marijuana can cause effects, including problems with emotional functioning, academic problems and even structural brain changes, said the paper published in JAMA Psychiatry.  And the earlier in life someone tries marijuana, the faster their transition to becoming dependent on the drug, or other substances. “Some people may believe that marijuana is not addictive or that it’s ‘better’ than other drugs that can cause dependence,” Heitzeg said adding, “but marijuana changes your brain in a way that may change your behaviour, and where you get your sense of reward from. It affects the brain in a way that may make it more difficult to stop using it.”  Also Read – Leslie doing new comedy special with NetflixPrevious research has shown that the brains of people who use a high-inducing drug repeatedly often respond more strongly when they’re shown cues related to that drug. The increased response means that the drug has become associated in their brains with positive, rewarding feelings. And that can make it harder to stop seeking out the drug and using it, said the researchers. “If this is true with marijuana users, it may be that the brain can drive the use of the drug, and that this use can also affect the brain,” said lead author Meghan Martz, doctoral student at the University of Michigan. For the study, the team involved 108 people in their early 20s – the prime age for marijuana use. All had brain scans at three points over four years.  While their brain was being scanned in a functional MRI scanner, they played a game that asked them to click a button when they saw a target on a screen in front of them. Before each round, they were told they might win 20 cents, or $5 – or that they might lose that amount, have no reward or loss.The researchers focussed on the nucleus accumbens – the reward centres of the volunteers’ brains. When a reward is being anticipated, the cells of the nucleus accumbens usually swing into action, pumping out dopamine – a ‘pleasure chemical.’ The bigger the response, the more pleasure or thrill a person feels and the more likely they’ll be to repeat the behaviour later.last_img read more