Month: August 2019

  • Physics duo offer explanation of why tiny bubbles last longer on a

    first_img Scientists know that the smaller the radii of curvature a bubble has, the less time it will tend to exist before popping. Thus, nano-sized bubbles should pop almost instantly, and in most cases they do. One exception is when they are sitting in a fluid that is covering a solid surface. In this case, nano-sized bubbles have been observed existing for up to days at a time, and until now, no one has been able to offer a reasonable explanation as to why this occurs.In their paper, the researchers argue that there are two factors at play. The first is the fact that due to the solid surface, the radii of curvature is increased relative to bubbles flowing freely of the same volume, because they are flattened out by the surface. This increases their strength. Second, the researchers noted that the longer lasting bubbles tended to exist in groups of bubbles, rather than as isolated entities. This they means that the liquid in which they all exists has more gas in it (expelled from the bubbles themselves) and thus because it is more saturated, it’s less able to accept more gas from the still existing bubbles. Free bubbles on the other hand, leave their gasses behind as they rise to the surface.Gaining a better understanding of bubble formation and popping is more than a mere curiosity – a more thorough understanding of the underlying principles could lead to better pumps in tiny machines or perhaps assist in the development of medical delivery systems. Also, learning how to prevent bubble formation may also help reduce problems that occur when they impede flow or change the course of fluids in dynamic systems. © 2013 Phys.org Mysterious nanobubble burst? Citation: Physics duo offer explanation of why tiny bubbles last longer on a surface (2013, February 4) retrieved 18 August 2019 from https://phys.org/news/2013-02-physics-duo-explanation-tiny-longer.html (Phys.org)—Physicists in The Netherlands, Detlef Lohse and Joost Weijs of the University of Twente, have offered an explanation of why nano-sized bubbles last considerably longer when sitting on a solid surface covered by a fluid, than when they are allowed float free. In their paper published in Physical Review Letters, the two argue that surface-held bubbles have increased radii of curvature and sit in pools of liquid infused with gas, which causes them to last longer. Sketch of a liquid layer in contact with a solid (left). The top of the liquid is exposed to atmospheric conditions. At the solid-liquid interface nanobubbles are present. The arrows indicate the gas flow direction. On the right a further enlargement of one nanobubble is shown. Credit: arxiv.org/abs/1210.3484center_img More information: Why Surface Nanobubbles Live for Hours, Phys. Rev. Lett. 110, 054501 (2013) link.aps.org/doi/10.1103/PhysRevLett.110.054501 . On ArXiv arxiv.org/abs/1210.3484AbstractWe present a theoretical model for the experimentally found but counterintuitive exceptionally long lifetime of surface nanobubbles. We can explain why, under normal experimental conditions, surface nanobubbles are stable for many hours or even up to days rather than the expected microseconds. The limited gas diffusion through the water in the far field, the cooperative effect of nanobubble clusters, and the pinned contact line of the nanobubbles lead to the slow dissolution rate. Explore further Journal information: Physical Review Letters 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

  • A closer look at the molecular mechanism that switches control of activation

    first_imgCredit: RIKEN A team of researchers at the RIKEN Center for Biosystems Dynamics Research in Japan has developed a tool to prevent neurogenerative diseases. They have demonstrated a way to observe the molecular mechanism that switches control of activation of eIF2 by eIF2B when a cell undergoes stress. In their paper published in the journal Science, the group describes their use of cryo-electron microscopy to better understand what happens to cells that are exposed to stress. Impaired energy metabolism linked with initiation of plaques in Alzheimer’s brain Cells continuously undergo a process known as translation in which ribosomes in cytoplasm synthesize proteins after transcription of DNA to RNA. But sometimes, this process is interrupted by an external event. Such events are known as stress—exposure to ultraviolet light is one common example. The researchers note that translation uses a lot of energy, thus it makes sense for cells to shut it down when a stress event occurs—it saves energy and reduces the chances of errors in the proteins that are synthesized.Prior research has shown that when a cell “senses” stress, the translational initiation factor eIF2 is phosphorylated. Under normal circumstances, eIF2 is activated by eIF2B, another translational initiation factor. But when the cell is under stress and eIF2 is phosphorylated, the function of eIF2B is inhibited, preventing translation. Scientists have been working to understand the molecular mechanism involved in discontinuation of translation due to stress, but the means of activation of eIF2 by eIF2B is still unknown. In this new effort, the researchers have found a way to look inside the cell nucleus to see what actually happens as syntheses of proteins ceases during stress.The researchers observed the structure of both eIF2 and eIF2B using cryo-electron microscopy. Doing so showed that the orientation of eIF2 as it was bound to eIF2B differed greatly depending on whether eIF2 had been phosphorylated. They also found that eIF2B had a two-fold symmetric structure and that the phosphorylation of eIF2 could be considered a mechanism that not only prevented the activation of phosphorylated eIF2, but also prevented the activation of other translational initiation factors. © 2019 Science X Network Journal information: Sciencecenter_img Explore further More information: Kazuhiro Kashiwagi et al. Structural basis for eIF2B inhibition in integrated stress response, Science (2019). DOI: 10.1126/science.aaw4104 Citation: A closer look at the molecular mechanism that switches control of activation of eIF2 by eIF2B (2019, May 3) retrieved 18 August 2019 from https://phys.org/news/2019-05-closer-molecular-mechanism-eif2-eif2b.html 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

  • Millihertz quasiperiodic oscillations detected in the Xray binary EXO 0748−676

    first_img X-ray binaries consist of a normal star or a white dwarf transferring mass onto a compact neutron star or a black hole. Based on the mass of the companion star, astronomers divide them into low-mass X-ray binaries (LMXBs) and high-mass X-ray binaries (HMXBs).Most of the low-mass X-ray binaries containing neutron stars (NS LMXBs) exhibit X-ray variability in the form of relatively sharp quasi-periodic oscillations (QPOs) with millihertz to kilohertz frequencies. It is believed that QPOs occur when X-rays are emitted near the inner edge of an accretion disk in which gas swirls onto a compact object like a neutron star or a black hole. Hence, astronomers hope that finding new objects with such oscillations could improve our knowledge about the innermost regions of accretion disks.Located most likely between 19,200 and 24,100 light years away, EXO 0748−676 is a transient NS LMXB discovered in 1985. With an orbital period of about 3.82 hours, the source showcases several-minutes-long eclipses in its X-ray light curve and irregular X-ray dips observed mostly in the half orbital cycle prior to the eclipse. First QPOs from this object at kilohertz frequencies were discovered in 2010.Now, combing through the data gathered by RXTE over a timespan of nearly 15 years, a team of astronomers led by Giulio Cesare Mancuso from the National University of La Plata, Argentina, has found that EXO 0748−676 also exhibits millihertz QPOs.”We report the discovery of millihertz quasi-periodic oscillations (mHz QPOs) from the bursting, high-inclination atoll neutron-star low-mass X-ray binary (NS LMXB) EXO0748–676 with the Rossi X-ray Time Explorer (RXTE),” the astronomers wrote in the paper.According to the study, the researchers were able to identify QPOs from EXO 0748−676 with frequencies ranging from 5.0 to 13 millihertz. The amplitude of the QPOs was about 4.0 percent at low energy (between 2.0 and 5.0 keV), and the astronomers also found that in at least two cases, the frequency of these oscillations decreased in time.Moreover, the astronomers noted that all the detections of QPOs occurred when the source energy spectrum was relatively soft. In one case, they found that the millihertz quasi-periodic oscillation disappeared after the onset of a thermonuclear X-ray burst. The study explains that millihertz QPOs like these detected in EXO 0748−676 are assumed to be due an oscillatory mode of helium burning on the surface of neutron stars, known as the marginally stable nuclear burning.Summing up their study, the authors noted that the detection makes EXO 0748–676 so far the sixth source with millihertz QPOs associated to marginally stable burning. They added that the results from RXTE also confirm this binary as the second one that shows a systematic frequency drift. AstroSAT observations reveal quasi-periodic oscillations in the X-ray binary GX 5-1 Citation: Millihertz quasi-periodic oscillations detected in the X-ray binary EXO 0748−676 (2019, May 14) retrieved 18 August 2019 from https://phys.org/news/2019-05-millihertz-quasi-periodic-oscillations-x-ray-binary.html Explore further RXTE/PCA light curve (≈ 2–5 keV) of EXO 0748–676 rebinned to 32 s in which the mHz QPOs are detected. Credit: Mancuso et al., 2019. © 2019 Science X Network By analyzing data from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite, astronomers have detected millihertz quasi-periodic oscillations from a low-mass neutron star X-ray binary designated EXO 0748−676. The finding is detailed in a paper published May 6 on the arXiv pre-print server. More information: Discovery of millihertz quasi-periodic oscillations in the X-ray binary EXO 0748—676, arXiv:1905.01956 [astro-ph.HE] arxiv.org/abs/1905.01956 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

  • A way to determine the absolute stereochemistry of small organic molecules

    first_imgDiffraction data collection and advanced diffracted intensity extraction. (A) Scanning of crystal during data collection. Beam and crystal shifts are indicated by white arrows. (B) Plot of the rocking-curve profiles of the experimental precession electron diffraction data collected on one of the four crystals used for determination of rocking-curve profile parameters. The lowest blue curve is the averaged rocking curve in the range of 0.2 to 0.3 Å−1 and the highest blue curve is the averaged rocking curve in the range of 0.9 to 1.0 Å−1. The precession angle is 0.65°. The red curves correspond to the fitted rocking-curve profiles with the FWHM of the interference function equal to 0.0005 Å−1 and an apparent mosaicity of 0.08°. (C) Comparison of intensity integration in case of sparse sampling of reciprocal space. Experimental points (blue) are fitted with rocking-curve profile (red line) and the resulting intensity corresponds to the red area. Blue area corresponds to the area under experimental points. Credit: Science (2019). DOI: 10.1126/science.aaw2560 As the researchers note, the current method for determining the absolute configuration of molecules that have chiral centers is done via X-ray crystallography. The measurement is based on observing how X-rays fired at molecules bounce around. Unfortunately, this method only works on relatively large crystal structures. Efforts to use a similar technique on smaller crystals based on electron diffraction have fallen short of expectations due to the fragile nature of the target—nanocrystals are destroyed by the energy in the electron beams. In this new effort, the researchers have found a way to overcome this problem, which allowed them to determine the stereochemistry of very small crystals for the first time. This is a pretty big deal, Xu and Zou note, because the U.S. FDA and the European Medicines Agency require absolute configuration information for a prospective new drug before it can be approved. This requirement has held back the creation and sale of drugs based on nanocrystals, as pharmaceutical companies had no way to fulfill the requirement.To overcome the problem of electron beams destroying nanocrystals before their stereochemistry could be recorded, the researchers simply used more beams—four of them. They fired them all at once at different parts of the nanocrystal and recorded information regarding the diffracting that occurred before the nanocrystal was destroyed.Xu and Zou note that X-rays scatter only once when used to determine the configuration of a molecule—with electron diffraction, electrons scatter multiple times, and as they do so, the intensities of their diffractions change—sensors that read such changes are able to measure such dynamical diffraction effects. The result was a description of the absolute stereochemistry of a given molecule. Xu and Zou suggest that the new technique is likely to open the door to development of new materials used in drug design. A team of researchers from several institutions in Czech Republic has developed a way to determine the absolute stereochemistry (3-D spatial configuration) of small, organic molecules. In their paper published in the journal Science, the group describes their new technique and how well it worked. Hongyi Xu and Xiaodong Zou with Stockholm University, have published a Perspective piece on the work done by the team in the same journal issue. 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. More information: Petr Brázda et al. Electron diffraction determines molecular absolute configuration in a pharmaceutical nanocrystal, Science (2019). DOI: 10.1126/science.aaw2560 Citation: A way to determine the absolute stereochemistry of small, organic molecules (2019, May 20) retrieved 18 August 2019 from https://phys.org/news/2019-05-absolute-stereochemistry-small-molecules.htmlcenter_img Journal information: Science © 2019 Science X Network Electron crystallography found to work as well as X-ray crystallography only on smaller crystals Explore furtherlast_img read more

  • Two planets orbiting Teegardens star described as most earthlike found yet

    first_img 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. , Astrophysical Journal More information: Amri Wandel et al. On the Habitability of Teegarden’s Star Planets, The Astrophysical Journal (2019). DOI: 10.3847/2041-8213/ab2df7 A pair of researchers, one with the Hebrew University of Jerusalem, the other Tel Aviv University, has found evidence that suggests two of Teegarden’s star planets are the most Earth-like found yet. In their paper published in The Astrophysical Journal Letters, Amri Wandel and Lev Tal-Or describe their study of the two exoplanets and what they found. Journal information: Astrophysical Journal Letters Citation: Two planets orbiting Teegarden’s star described as most earthlike found yet (2019, August 8) retrieved 18 August 2019 from https://phys.org/news/2019-08-planets-orbiting-teegarden-star-earthlike.html © 2019 Science X Network New Earth-like exoplanets discovered around red dwarf Teegarden star Credit: CC0 Public Domain Back in 2003, astrophysicist Bonnard Teegarden led a team that discovered what is now known as Teegarden’s star—a red M dwarf star approximately 12.5 light-years away. Since that time, space scientists have studied both the star and the planets that make up its star system. In this new effort, the researchers focused their efforts on two of those exoplanets, which are called Teegarden’s star b and c—both were first detected this past June by a team working on the CARMENES survey.The work by Wandel and Tal-Or was focused on learning more about the habitability of the two exoplanets. As part of that effort, they noted that both are relatively close to their star, with orbits of just 4.9 and 11.4 days, putting them both firmly in the Goldilocks zone. They note that both are tidally locked, which means one side always faces the sun, which also means they have no day/night cycle.The researchers acknowledge that it is not known what sort of atmospheres the two planets have, but suggest it is likely either or both could support water. This is because they are tidally locked, which means that even a thin atmosphere would be enough to spread the warmth and cold across the dark/light dividing line. They calculated that atmospheres between one-third that of Earth’s or as much as 17 times as dense would allow for liquid water to exist on the surface of either planet. They also note that both of the planets are near in size to Earth. And as part of applying an analytic habitability model to the planets, the researchers calculated that Teegarden b has a 60 percent chance of having surface temperatures between zero and 50 degrees C—Teegarden c was found to be colder, much more like Mars. The researchers conclude that conditions in the transition zone appear to be favorable for supporting life. Explore furtherlast_img read more

  • Sealdah mainline disrupted after irate commuters ransacked Sodhpur station

    first_imgKolkata: Station master cabin and railway properties were ransacked and railway tracks blocked at Sodhpur station in North 24 Parganas, disrupting traffic on mainline of Eastern Railway connecting Sealdah, at peak hours today. The irate commuters, after an alleged wrong announcement regarding Sealdah bound Gedhe local train, plundered the station premises and obstructed railway tracks, official sources said.The disruption began around 10 00 hours, causing detention of many long distance and local trains both up and down lines, as hundreds of protesters squatted on the track, about 16 kms north of Sealdah terminal of ER. The situation went out of control as the number of protesters outnumbered the RPF and GRP personnels at Sodhpur station. Also Read – Heavy rain hits traffic, flightsTrouble ensued when the train did not stop even after the public address system at Sodhpur station announced that the Sealdah bound Gedhe EMU would halt on platform number 2. The passengers, mostly officer goers, who had taken position after crossing open tracks to board the train lost their cool and began expressing their resentment through violent agitation.ER’s CPRO, Ravi Mahapatro, said, though talks were going on to add Shodhpur station to the existing stoppages of that particular EMU, nothing has been finalised by the authorities yet. He said an inquiry has been ordered to ascertain, if there was an announcement for the halt today.He said the agitation caused detention of many long and short distance trains and cancellation of some EMUs, so far on the section.The blockade was continuing when the report came in.last_img read more

  • Digha Mandarmani on alert due to high tide

    first_imgKolkata: The district administration of East Midnapore issued an alert in the coastal areas of Digha and Mandarmani due to high tidal waves.Digha and Mandaramani are the major tourist spots in the state, with recorded number of footfall. There was a huge tidal wave hit on Wednesday. Many people were seen taking photographs of the rough sea. While some others tried to take selfies with the rough sea in the background. Police and district administration urged the visitors to not go near the sea and watch it only from a distance.According to a weather expert, there is a high tide in Digha and the fishermen have been advised against venturing into the sea. .Tourists, who had assembled near Digha and Mandarmani beaches to enjoy the high tide, were asked not to congregate near the sea shore as precautionary measures.last_img read more

  • HiroshimaNagasaki Blood splattered legacy

    first_imgNow if you visit these places, all you would see are structures built in the memory of the lost cities with silent cries of the victims buried under the debris caused by the devastation. These heritage sites exist only to remind mankind of the evil that resides in their very being.Some of the heritage sites which stand as a testament of human destruction are Birkenau Concentration Camp (Poland) where the Nazi Germans slaughtered the Jewish people, the Island of Goree in Senegal that was used as a base in slave trade and the Robben Island in the Republic of South Africa where people opposing the apartheid were imprisoned. Also Read – ‘Playing Jojo was emotionally exhausting’The Genbaku Dome in Japan fulfills the criteria of a memorial erected directly because of the evils of warfare. The dome is basically the ruin of the former Hiroshima Industrial Promotion Hall that was destroyed after the first atomic bomb was dropped directly on top of it, resulting in only the walls being partially spared and the characteristic form of the building remaining with the iron frame of the dome.Situated on the opposite bank of the Motoyashu River which runs past the dome, is the Peace Memorial Park where the Hiroshima Peace Memorial, the Atomic Bomb Memorial Mound, Children’s Peace Monument are built. There is also a cenotaph built to pay respects to the deceased souls of the atomic blast. Also Read – Leslie doing new comedy special with NetflixOn August 6th every year, in the Peace Memorial Park in front of the Hiroshima Peace City Monument, a peace memorial ceremony is held to appease the souls of those destroyed by the atomic bomb as well as to pray for the eternal peace on Earth. During the ceremony, the Peace Declaration read out by the Mayor of Hiroshima city, which appeals for the abolition of nuclear weapons and for the realisation of world peace, is transmitted worldwide. At exactly 8.15 am, which is the precise time when the atomic bomb was dropped years ago, the Peace Bell is rung and the citizens offer silent prayers for one minute for the repose of the souls of the bomb victims. Like Hiroshima, another city was also completely destroyed by the August bombings. A certain city which goes by the name of Nagasaki was also reduced to ash on the 9th of August. More than 750,000 lives were wiped out and the damage to property was countless. The survivors, even after so many years, cannot forget the horrific tragedy that had befallen them on that fateful day. To commemorate the fallen and to prevent the recurrence of such disasters to happen, a statue Heiwa Kinen-Zo was built by Seibo Kitamura, a local sculptor in 1955. The statue which is made completely of bronze is 9.7 meters in height and weighs around 30 tons. According to common lore, the statue’s right hand is raised upwards to point to the threat of nuclear wars while the horizontally extended left hand symbolises peace. The surrounding area of the statue located in the Nagasaki Peace Park is a designated zone to pray for world peace and also has the Fountain of Peace attached to it, in order to mourn for the victims’ souls who died there while seeking water. Every year on August 9 the Nagasaki Memorial service for the Dead and Peace Ceremony are held in front of the statue.last_img read more

  • Raising national awareness over childhood cancer

    first_imgThe joy reflecting on Iqbal’s face belied the braveheart’s ongoing fight with blood cancer. As the seven-year-old played with a balloon, Rajasthan Health Minister Rajendra Rathore inquired from his parents about his treatment here.Giving Iqbal company are Rakesh, 6, and Ankit, 4, who too are also undergoing treatment for blood cancer. “We were also given school bags,” said Rakesh. The three children, along with many others, came together at the public forum organised by an NGO to mark the joining of hands with the state government to spread awareness on childhood cancer. Also Read – ‘Playing Jojo was emotionally exhausting’Iqbal’s father, Sikandar, a resident of Pali district, said he and many others like him who have been getting their children treated for cancer in Jaipur are enthused by the event. “We all have now come together as a community. Earlier, we were working in isolation,” he said, pointing to the help by NGO Cankids Kidscan.The public forum was held in mid-September to mark the arrival of the ‘CanKids 4th Car Rally — Change for Childhood Cancer in Rajasthan’ in Jaipur as a part of an initiative to spread awareness and join hands with the state government to open a cancer awareness unit for patients and their family members at Sawai Man Singh Hospital here.  Also Read – Leslie doing new comedy special with NetflixThe rallyists mostly consisted of drivers who either overcame cancer or those who have joined hands with Cankids Kidscan — a national society to raise awareness and funds for fighting cancer among kids. “The 1,700-km rally also touched cities like Ajmer and Udaipur and villages around them,” said Hodgkins survivor and Cankids advocacy officer Kapil Chawla. Cankids volunteer and National Girl Childhood Cancer Ambassador Ritu Bhalla, 24, a two-time child cancer survivor herself, also took part in the rally and shared her experience of overcoming the disease. “Some people were struck by disbelief when I told them that I have overcome cancer twice and am working normally now,” Bhalla said on returning to Delhi after the four-day rally with 30 participants.Before reaching Jaipur, volunteers of the NGO, along with the rallyists, stopped over at Mayo College Girls School in Ajmer for an awareness event. Ashwin Khandke, a corporate honcho and rally participant who lost his wife to cancer a few weeks before the event, addressed the school students, including his own daughter Sunetra, about how courage and hope were the key to fighting the disease. “Do not let fear overcome you,” said Khandke at the school’s auditorium where the students, from both Mayo Girls and Mayo Boys, were moved to give a standing ovation to the Khandke family, and others in the rally, who are symbols of bravery and courage as they have fought the dreaded disease.last_img read more

  • WB BJP planning all party condolence meeting for Vajpayee

    first_imgKolkata: The West Bengal BJP unit is planning to organize an all party condolence meeting for former prime minister Atal Bihari Vajpayee who passed away in New Delhi on August 16. “In Kolkata we are planning to hold an all party condolence and prayer meeting for Vajpayee ji. He was not only a former prime minister of India but was one of the greatest mass leaders of Independent India. He was loved and respected across party lines,” BJP national secretary Rahul Sinha said. Also Read – Rain batters Kolkata, cripples normal life It is still in the planning stage nothing has been finalized as of now. We will invite leaders of all political parties and eminent citizens. His friends and admirers in Kolkata will also be invited, Sinha said. When asked whether the BJP expects leaders across political lines especially the TMC to attend the condolence meet, another senior state BJP leader said it was for TMC to decide. The TMC declined to comment on the issue. Atal Bihari Vajpayee, one of India’s most charismatic leaders who led the nation through several crises and held together a tenuous coalition with his inclusive politics, died on Aug 16 in New Delhi. He was 93.last_img read more