Month: August 2019

Selfassembling solar panels a step closer

first_imgThe self assembly process made a device of 64,000 parts in 3 minutes. Image: Heiko O. Jacobs © 2010 Explore further The self assembly process. Elements align at the oil/water boundary. The “blank” solar cell has pre-cut places for the elements and is dipped through the boundary. As it is slowly drawn upwards, the elements pop into place. Image: Heiko O. Jacobs. ( — Scientists Robert J. Knuesel and Heiko O. Jacobs of the University of Minnesota have developed a way to make tiny solar cells self-assemble. New nanoassembly technique is created Citation: Self-assembling solar panels a step closer (2010, January 14) retrieved 18 August 2019 from More information: Self-assembly of microscopic chiplets at a liquid-liquid-solid interface forming a flexible segmented monocrystalline solar cell, Robert J. Knuesel and Heiko O. Jacobs, PNAS, DOI:10.1073/pnas.0909482107 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. The researchers think they can adapt their method to smaller components and larger assembled devices, and it could be used to cheaply and quickly assemble all kinds of high-quality electronic components on a wide range of flexible or inflexible substrates including plastics, semiconductors and metals. The assemblages could find uses in numerous applications such as solar cells, video displays and tiny semiconductors. The use of this method in solar cell production would reduce the cost considerably since less silicon is needed, and it should also be possible to assemble solar chiplets into transparent, flexible materials, which would extend their range of uses.The paper is published in the Proceedings of the National Academy of Sciences (PNAS). The researchers had previously been unsuccessful in their attempts to make self-assembling electronic components. In large systems gravity can be used to drive self-assembly, and in nanoscale systems chemical processes can be used, but between the two scales, in the micrometer range, it is much more difficult.To overcome the difficulties, Kneusel and Jacobs designed a flexible substrate of a thin layer of copper covered with propylene-terephthalate (PET). Regular depressions the same size as the “chiplets” were etched into the PET layer and then the sheet was dipped into a bath of molten solder, which coated the exposed copper in the etched depressions. Each chiplet consisted of a 20-60 µm silicon cube with one gold face. The silicon sides had a coating of hydrophobic (water-repelling) molecules, while the gold side had a hydrophilic (water-attracting) coating.When the elements were placed in a container containing oil and water, they neatly arranged themselves in a sheet at the boundary between the liquids, with the gold side pointed down to the water layer. The substrate was then pulled slowly up through the boundary like a conveyor belt, and the elements neatly dropped in place in the depressions as the solder attracted the gold side. Accuracy was 98%. The assembly was covered with epoxy to keep the chiplets in place, and then a conducting electrode layer was added.The device was able to assemble 62,000 elements, each of them thinner than a human hair, in only three minutes. The elimination of a dependency on gravity and sedimentation meant the chiplets could be reduced to below 100 micrometers in size. It was important to limit the assembly time to avoid oxidation of the surfaces, which would reduce surface energies and interfere with self-assembly. The water layer had to be acidic, at pH 2.0, and the temperature had to be kept at 95C to keep the solder molten.last_img read more

Physicists propose test for loop quantum gravity

center_img In this way, evaporating black holes could enable the first ever experimental test for any theory of quantum gravity. However, the proposed test would not be easy, since scientists have not yet been able to detect any kind of radiation from an evaporating black hole. The scientists, from institutions in France and the US, have published their study called “Probing Loop Quantum Gravity with Evaporating Black Holes” in a recent issue of Physical Review Letters.“For decades, Planck-scale physics has been thought to be untestable,” coauthor Aurélien Barrau of the French National Institute of Nuclear and Particle Physics (IN2P3) told “Nowadays, it seems that it might enter the realm of experimental physics! This is very exciting, especially in the appealing framework of loop quantum gravity.”In their study, the scientists have used algorithms to show that primordial black holes are expected to reveal two distinct loop quantum gravity signatures, while larger black holes are expected to reveal one distinct signature. These signatures refer to features in the black hole’s energy spectrum, such as broad peaks at certain energy levels.Using Monte Carlo simulations, the scientists estimated the circumstances under which they could discriminate the predicted signatures of loop quantum gravity and those of the Hawking radiation that black holes are expected to emit with or without loop quantum gravity. They found that a discrimination is possible as long as there are enough black holes or a relatively small error on the energy reconstruction.While the scientists have shown that an analysis of black hole evaporation could possibly serve as a probe for loop quantum gravity, they note that one of the biggest challenges will be simply detecting evaporating black holes. “We should be honest: this detection will be difficult,” Barrau said. “But it is far from being impossible.”He added that black holes are not the only possible probe of loop quantum gravity, and he’s currently investigating whether loop quantum gravity might have signatures in the universe’s background radiation.“I am now working on the cosmological side of loop quantum gravity,” Barrau said. “This is the other way to try to test the theory: some specific footprints in the cosmic microwave background might be detected in the future.” Copyright 2012 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of 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. Escaping gravity’s clutches: The black hole breakoutlast_img read more

Google might launch Drive for cloud storage soon

first_img © 2011 Explore further Citation: Google might launch Drive for cloud storage soon (2012, February 12) retrieved 18 August 2019 from More information: … 211961645711988.html Google, as observers already point out, has significant “stickiness” with an array of services surrounding documents and communications; its extension into cloud storage is seen as important to watch.Drive will allow the user to store files and retrieve the files from Internet-connected devices, be it smartphones, tablets, or any other. The launch is reportedly planned for any time soon—possibly in the coming weeks.Information that can be Drive-stored is to include photos, documents, and videos, which would land on Google’s servers. This type of online storage system sounds familiar to those familiar with Dropbox, which has enjoyed success. Dropbox has 50 million users, according to reports, and similarly allows users to store photos, documents and other material so users can always access them from PCs, smartphones, or other devices. Google and Dropbox also bear resemblance in pay models–Google’s Drive service will be free, but users who store large amounts of data will have to pay.Similarly, Dropbox offers 2GB for free but collects $9.99 per month from customers who want 50 GB of data per month and Dropbox charges $19.99 per month for 100GB.Apple offers iCloud and Microsoft, SkyDrive, but much of the press attention is focusing on Dropbox and what Google’s entry might do to threaten the popularity of Dropbox.Another question being posed is whether Google’s business executives will be content with simply a tiered subscription payment model or whether the company will be getting into the more lucrative business of scanning the user’s data for the purpose of sending targeted ads. This might ruffle watchdog groups sensitive to threats to privacy.Lastly, there is the all-familiar question about cloud storage versus maintaining security for large businesses. Some cloud-computing watchers worry over the idea of employees storing certain information on a service that the companies cannot directly control. Ensuring security measures to automatically stop people from sharing confidential documents has been one suggestion in the ongoing conversation about cloud services and security.However, if Dropbox, which enables enabled iPads, Android phones and PCs to work together, is any indication, a number of businesses do feel comfortable about file-sharing services from Dropbox. According to a report last year in The New York Times, “millions” signed up with their work e-mail addresses to Dropbox and the company estimated that at least one million businesses used the service.Yet another company,, has had success in targeting business customers by spelling out advantages of using its file-sharing services without incurring headaches over compromised security. tells customers that “protecting your corporate content is our top priority.” The company says it has invested heavily in security and resiliency at its data centers.last_img read more

Researchers build model that may explain how plate tectonics got its start

center_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 More information: Plate tectonics, damage and inheritance, Nature (2014) DOI: 10.1038/nature13072AbstractThe initiation of plate tectonics on Earth is a critical event in our planet’s history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks1, 2), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. An idealized simulation showing how plate-tectonic boundaries (including complex ones) emerge because of inherited damage following a shift in plate-tectonic driving forces; in this case the shift is similar to that which caused the Emperor-Hawaiian Bend in the Pacific. Credit: David Bercovici Citation: Researchers build model that may explain how plate tectonics got its start (2014, April 7) retrieved 18 August 2019 from 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. An idealized simulation showing how plate-tectonic boundaries (including complex ones) emerge because of inherited damage following a shift in plate-tectonic driving forces; in this case the shift is similar to that which caused the Emperor-Hawaiian Bend in the Pacific. Credit: David Bercovicilast_img read more

Metalcatalyzed addition of saturated carbon into CC bonds A relevant reaction for

first_img Carbanion analogs derived from naturally-occurring aldehydes (—Type II polyketides are a class of compounds found in nature as secondary metabolites derived from microorganisms. Their complex structures are characterized by fused polycyclic aromatic rings decorated with a profusion of ketones and hydroxyl groups. Many common antibiotics, anti-fungal, and anti-cancer drugs are type II polyketides or are derivatives of these naturally-occurring compounds. However the “laboratory synthesis” of type II polyketides is often challenging; as in living systems, it is a highly selective multi-step enzymatic process. © 2017 More information: Matthias Bender et al. Ruthenium-catalyzed insertion of adjacent diol carbon atoms into C-C bonds: Entry to type II polyketides, Science (2017). DOI: 10.1126/science.aao0453AbstractCurrent catalytic processes involving carbon-carbon bond activation rely on π-unsaturated coupling partners. Exploiting the concept of transfer hydrogenative coupling, we report a ruthenium(0)-catalyzed cycloaddition of benzocyclobutenones that functionalizes two adjacent saturated diol carbon-hydrogen bonds. These regio- and diastereoselective processes enable convergent construction of type II polyketide substructures. Researchers from the University of Texas led by Professor Michael J. Krische have developed a ruthenium-catalyzed cycloaddition of benzocyclobutenones and diols that directly deliver substructures found in diverse type II polyketides. Their catalytic reactions involve successive insertion of saturated diol carbon-hydrogen (C-H) bonds into a carbon-carbon (C-C) bond by way of a ruthenacycle intermediate. Their report appears in Science.This research builds on prior studies by this group on metal-catalyzed C-C bond forming reactions of alcohols via hydrogen transfer—a modern twist on carbonyl addition chemistry. Whereas classical carbonyl additions typically involve the reaction of pre-formed organometallic reagents with an aldehyde or ketone (e.g., a Grignard reaction), in the current paper these reactive species are generated transiently and in duplicate. The ruthenium catalyst inserts into a stained C-C bond to form a ruthenacycle bearing TWO carbon-ruthenium bonds, and the catalyst converts the diol to a transient diketone. These species engage in double-carbonyl addition that results in cycloaddition. The net result is the formal insertion of two saturated diol C-H bonds into a saturated C-C bond.As a model reaction to test their concept, the authors reacted benzocyclobutenone with trans-cyclohexane 1,2-diol in the presence of their ruthenium catalyst. After tweaking the reaction conditions, they obtained an 88% yield of the tricyclic product bearing a bridgehead diol, which formed exclusively as the syn-stereoisomer. To examine the versatility of their conditions, they reacted a range of benzocyclobutenones with a variety of 1,2-diols. Several of the diols tested had fused rings. This resulted in the formation of cycloadducts with tetracyclic substrates found in several type-II polyketides, including angucycline natural products with congested “bay-region” architectures. Notably, each of the reactions displayed complete regio- and stereoselectivity. Additionally, the reaction tolerated halide substitution on the benzene ring allowing for further functionalization. Studies to elucidate the reaction mechanism showed that the cycloaddition can be performed in a redox-independent manner. That is, the benzocyclobutenone can react with a diol, a ketol, or a dione producing the same product as a single regio- and stereoisomer. While the reaction of the diol is oxidative and requires a slight excess of benzocyclobutenone, the reaction of the ketol is redox-neutral and can be performed with equal amounts of benzocyclobutenone and ketol. The reductive reaction of the dione requires the addition of 2-propanol to act as a reductantBeyond broadening access to type II polyketides, the reactivity embodied by these studies has broader implications in the field of chemical synthesis. Dr. Michael Krische told PhysOrg, “In contrast to progress recently made in the field of C-H activation, the development of catalysts that modify C-C sigma-bonds has lagged behind, and is largely restricted to intramolecular reactions that insert tethered π-bonds, often requiring directing-groups. Hydrogen-transfer offers a broad, new approach to the functionalization of C-C bonds using abundant, renewable alcohols as coupling partners.” 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.center_img Journal information: Science Ruthenium-catalyzed cyclobutenone-diol [4+2]cycloaddition via C-C bond activation: A gateway to type II polyketide natural products. Credit: (c) Science (2017). DOI: 10.1126/science.aao0453 Explore further Citation: Metal-catalyzed addition of saturated carbon into C-C bonds: A relevant reaction for the synthesis type II polyketides (2017, September 15) retrieved 18 August 2019 from read more

Diffusiophoresis found to be critical factor for getting clothes clean

center_img © 2018 Cleans better than the leading brand. Rinsing soapy, stained cotton with fresh water (right) works far better than rinsing with detergent-filled water (left). The difference is that fresh water produces detergent gradients that draw out dirt particles. Credit: Physical Review Applied (2018). DOI: 10.1103/PhysRevApplied.9.034012 Panning for silver in laundry wastewater Humans have probably been washing their clothes for as long as they have been wearing them. The typical process generally involves swishing the clothes in water containing some type of detergent, followed by rinsing with clean water. Interestingly, despite this long history, it is unclear how, exactly, clothes become clean from this regimen. In this new effort, the research team conducted experiments in the lab to figure it out.Stains, the researchers note, are usually due to staining agents infiltrating into small pores in fabric via capillary action. In order to clean them, a liquid must be able to make its way into the pore and then somehow pull out the staining agent. To learn more about how this process works, the researchers created material with tiny tubes 10 microns in diameter to serve as a sort of fabric—tiny polystyrene balls served as the staining agent. The researchers then “stained” their fabric and filmed the action with a microscope as the material was cleaned.The team reports that the water with the detergent was unable to infiltrate all the way into the pore, but because the detergent contained ingredients that prevented the material from repelling water while also attracting the staining agent, the stain was primed for removal. When the water containing detergent was replaced with clean water, the staining agent was pulled from the pores due to chemophoresis. Interestingly, they found that if they tried rinsing the material with detergent-bearing water, chemophoresis did not occur and the stain remained in place. 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

NTPC to bring down coal import bill to nil in 5 years

first_imgState-run NTPC is looking at bringing its coal import bill to ‘zero’ in the next five years and will rely on the fossil fuel made available by Coal India and the company’s own mines.The power major is one of the country’s largest consumers of coal. “Our aim is to have zero import of coal, and manage with the coal from Coal India sources or our own mines,” NTPC CMD Arup Roy Choudhury told PTI in an interview.When asked about the timeframe in which the PSU plans to have nil coal imports, Choudhury said, “You can say in the next five years.” NTPC ventured into coal mining as part of its backward integration process for fuel security. The company has been allotted 10 coal blocks including Chatti-Bariatu, Chatti-Bariatu (South) and Kerandari in Jharkhand, Dulanga in Odisha and Talaipalli in Chhattisgarh. Its another block — Pakri-Barwadih — in Jharkhand is likely to commence coal production by the end of this calender year and the remaining mines subsequently. “Pakri-Barwadih will come this year (2015) and others later,” Choudhury said. NTPC imported close to 16 million tonnes (MT) of coal in the just-concluded fiscal compared to 10 MT in 2013-14. Meanwhile, the PSU, which is also the country’s largest power producer, is establishing 4,000 MW imported coal-based thermal power plant at Visakhapatnam district in Andhra Pradesh at an investment of about Rs 20,000 crore. NTPC’s present installed capacity is 44,398 MW comprising 39 generating stations.last_img read more

Three incidents of fire in city none injured

first_imgKolkata: Fire broke out at three places in the city on Saturday and Sunday. None was, however, hurt in these fire incidents.According to police, on Saturday night around 11:45 pm, fire broke out inside a meter box near the emergency ward of Bangur Institute of Neurology.As the impression of recent fire incident at Calcutta Medical College is still on the minds of people, the patients got panic-stricken.The relatives of the patients were waiting eagerly thinking if there keens needed to be shifted elsewhere. Also Read – Rain batters Kolkata, cripples normal lifeBut nothing such happened as one fire tender quickly reached the spot and doused the flames within 15 minutes. It is assumed that the fire occurred due to some electrical disorder.Another fire incident occurred on the top floor of a six-storied building on Park Street. At around 11:30 pm on Saturday, a fire broke out at the office of a herbal product company. The fire spread to the whole office immediately.Four fire tenders were pressed in to action. While firefighters were trying to put off the fire, a portion of the building was evacuated for safety reasons. The owner of the building was also informed. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedAfter almost two hours at around 1:25 am, the fire was controlled. In this case as well, the fire brigade personnel assumed the fire might have occurred due to an electrical disorder.In another incident early on Sunday morning, a moving light goods vehicle caught fire on Belvedere Road near Alipore zoo.At around 5:05 am, the driver of the vehicle felt the heat while driving. Almost immediately he noticed smoke billowing out of the frontal part of the vehicle.He stopped the vehicle and got down without losing a second. After getting off from the vehicle, he informed the police and fire brigade.One fire tender doused the fire within half an hour. The damage and cause of fire is yet to be ascertained.last_img read more

Girl goes missing after falling into river at Haroa

first_imgKolkata: A girl went missing after falling into river Bidyadhari at Haroa in North 24-Parganas. The incident took place on Wednesday. Police said that the girl was playing on the bank of the river with her sister and another boy, who is her neighbour. Preliminary investigation has revealed that the girl had slipped and accidentally fell into the river when she went to take water from the river. The two others also jumped into the river to save her. But none of them could return to the bank due to the high tide. Also Read – Rain batters Kolkata, cripples normal lifeSome boatmen found them crying for help and took necessary steps to save them from getting washed away by the high tide. The boatmen managed to rescue two of them with one remaining missing. The police were informed about the matter. Policemen from the local police station went to the spot and initiated rescue work. Later, officers of the Disaster Management Group (DMG) also stepped into action and took all necessary measures to find the girl. Many people gathered at the bank of the river when they came to know about the incident.last_img read more

Calcutta Medical College Hospital performs heart transplant on 38yearold patient

first_imgKolkata: The Calcutta Medical College and Hospital (CMCH) is the first government-run hospital in the state to perform a heart transplant on a 38-year-old man who had been undergoing treatment here at the hospital following severe heart-related ailments.It was learnt that Chief Minister Mamata Banerjee has also congratulated the hospital authorities for their achievement. Incidentally, it may be mentioned here that CMCH is the first medical college and hospital in the city obtaining the clearance from the state Health department in June this year. The state Health department officials inspected the CMCH and examined the infrastructure available to carry out such a surgery. A certificate of registration was issued to the Asia’s oldest medical college which will remain valid for five years from the date of issuance of license. Also Read – Rain batters Kolkata, cripples normal lifeOne Saikat Lattu (30), a resident of Pujali in South 24-Parganas, was declared brain dead at SSKM Hospital on Friday. As the family members of the victim agreed to donate his organs, the hospital authorities informed the matter to the Regional Organ and Tissue Transplant Organisation (ROTTO) which allocated the heart to the CMCH after it came to know that one patient admitted at the hospital required a heart transplant. The SSKM doctors retrieved the heart from the victim after his father, Swadesh Lattu, gave his consent for the same. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedThe heart was taken to the CMCH from SSKM within eight minutes through a green corridor felicitated by the city police on Saturday morning. A 12-member team of doctors was constituted at the CMCH to carry out the surgery. According to the hospital authorities, the heart was successfully transplanted on Rakhal Das (38) who had serious heart ailments for a long time. He has been kept under observation for the next 72 hours. The city has seen a spurt in organ donation in recent times due to the state government’s drive for awareness about deceased donor organ transplants. It can be said that SSKM Hospital has performed a series of liver and kidney transplants in the past two years but the CMCH has achieved a significant milestone by successfully conducting the heart transplant on Saturday.last_img read more

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