Green Vehicles´ battery-powered TRIAC can reach speeds of 80 mph. Credit: Green Vehicles. Citation: 80-mph electric car to go on sale this summer in the US (2008, May 8) retrieved 18 August 2019 from https://phys.org/news/2008-05-mph-electric-car-sale-summer.html With the two models, the company hopes to liven up the electric vehicle market by focusing on being environmentally friendly and affordable. The TRIAC, which has a five-speed transmission, will sell for an estimated $20,000. Price information on the BUCKSHOT, which has a three-speed transmission, has not yet been released.Both car and truck run on a 20kW AC motor, and have onboard chargers that can be plugged into a 120V or 240V outlet. Green Vehicles says that the TRIAC can run for about 100 miles on a full charge when driven at an average speed of 45 mph. Regarding the BUCKSHOT, the company says that “this is a true work truck, with close attention paid to payload capacity, torque, and durability. For deliveries, the BUCKSHOT can come with a lockable cargo shell; for construction, a steel lumber rack; and for all-purpose functionality, a steel body with an extra-long bed and an ample passenger cabin.” They suggest that the truck could be attractive to universities, businesses and municipalities. Green Vehicles also revealed that they are working on two neighborhood electric vehicles (NEVs) called the Microwatt and the Moose. The company hopes to bring these low-speed, short-distance electric vehicles to market in the fall. More information: www.greenvehicles.com (full Web site coming soon)via: AutoblogGreen Explore further The war on Southern California smog is slipping. Fixing it is a $14 billion problem Green Vehicles, a company based in San Jose, California, has recently revealed that it will begin selling two lithium-ion-powered electric vehicles early this summer. The three-wheeled TRIAC is a highway-capable electric car (or oversized covered trike, depending on how you look at it) that can reach speeds of 80 mph. There’s also the BUCKSHOT, an electric all-purpose work truck designed for heavy-duty, durable use. 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 Superbus holds 23 passengers is made with super light carbon fiber materials, and is powered by an electric motor backed up by lithium polymer batteries. The chief design engineer on the team is Antonia Terzi, formerly of BMW-Williams Formula 1, hence the aerodynamic design that cuts down on energy needs and allows the vehicle to travel safely at high speeds. Inside, it’s all about comfort and luxury, with seats that look like something off a roller-coaster, television, internet access and air bags for the passengers; up front, there’s space age technology for the driver; obstacle detection, navigational aids and state of the art communications and fail-safe backup systems.If the Superbus passes the government inspections in the UAE, it’s likely to go into service there, and if that happens, other urban planners are likely to take notice and begin considering orders themselves. More information: www.superbusproject.com/ Though it does look good, the Superbus, as it’s called, has been named more for its speed, than for its beauty and mobility, and is set to go for a test run in the UAE and might just wind up as a means to travel from Abu Dhabi to Dubai in a just 30 minutes, rather than the usual hour and a half. Citation: Former Dutch astronaut leads development of Superbus (w/ video) (2011, April 12) retrieved 18 August 2019 from https://phys.org/news/2011-04-dutch-astronaut-superbus-video.html Explore further 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 designers hope that the Superbus might be the answer to urban congestion. It’s as long as a normal public transportation bus, but it’s far more mobile thanks to two pairs of rear wheels that can turn independently, thus reducing the turning radius. The idea is that the Superbus would come to your house when you call, and pick you up, rather than you going to a bus stop. It would maneuver almost like a limousine through normal traffic, then go into high-speed mode on a dedicated concrete road, then maneuver normally near your destination. (PhysOrg.com) — Former Dutch astronaut Wubbo Ockels, once a mission specialist on the Challenger, has of late been working with a design team from TU Delft University, in Delft, to come up with a new kind of vehicle for public transportation. What they’ve come up with might just change how people view the lowly bus. Instead of a tall box-like cabin with an aisle and hard wide seats, the Superbus is aerodynamic, low and sleek, with eight gull-wing side doors and luxurious cushioned seats and can travel at speeds of up to 155 mph. © 2010 PhysOrg.com GM’s EN-V Envisions Future of Personal Mobility
Treansportation engineers will want to see how the Flybus rates in a focus on what is next in the evolution of the hybrid bus and solutions that can ease fuel consumption and CO2 emissions. Cost has been a challenge with standard hybrids. The new Flybus hybrid has taken on cost considerations with a unique energy-saving approach. The bus makes use of the “flywheel” technique demonstrated earlier this year by Porsche in Detroit. The flywheel can feed energy back into the wheels on the vehicle’s acceleration. The technique is praised as a way to generate emissions-free energy. The system takes the kinetic energy that is generated from the braking stops-and starts of a city bus run and sends it back to the vehicle. The team’s goal has been to come up with an energy-efficient redistribution process, supported by a continuously variable transmission system. Citation: ‘Flybus’ prototype may be hybrid bus of future (2011, September 8) retrieved 18 August 2019 from https://phys.org/news/2011-09-flybus-prototype-hybrid-bus-future.html (PhysOrg.com) — The “Flybus” prototype bus aims to showcase how hybrid electric buses can be inexpensive, cost efficient and easy on the environment. Reports out this week say that the Flybus is being readied for testing. The consortium of companies that created the prototype wlll stage a presentation at this year’s Low Carbon Vehicle event in the UK, at Rockingham Motor Speedway in Corby, Northamptonshire. Explore further Play Flybus flywheel-based mechanical hybrid system. Torotrack presentation. The Flybus consortium would like to see its prototype through the next stages so that bus operators can look forward to less fuel costs and brake wear. The group unites bus maker Optare, engineering consultancy Ricardo, technology specialist Torotrak, and Allison Transmission.London plans to introduce 90 hybrid buses to service this year. The city has been looking toward hybrid buses for some time. In the 2004 Energy Strategy plan, the Mayor adopted for London the government’s national targets to reduce carbon emissions by 60 per cent by 2050 from the 1990 level. Hybrid buses are taken seriously as a next step toward that goal. 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 Key features of the Flybus prototype are a Ricardo Kinergy flywheel as the medium for energy storage and a Torotrak continuously variable transmission (CVT) which transfers energy to the flywheel. The Ricardo Kinergy flywheel uses low-cost magnetic coupling. As interesting as the construct is the structure of the group, the Flybus consortium, that came up with the bus hybrid. The consortium is an example of what happens when there is a synergy between government and technologists at different companies who can put pieces of a product engineering puzzle together, drawing on varied areas of expertise, in an innovative way. The collaborative is partly funded by the UK’s Technology Strategy Board as part of its Low Carbon Vehicles initiative. More information: Press release © 2011 PhysOrg.com 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. Hybrid Bus in the City: A Prototype with a Future
The multicolor CRISPR labeling system exploiting Cas9 orthologs. Designs of dCas9 (“d” for “nuclease-dead”) ortholog-fluorescent proteins: S. pyogenes Sp dCas9, N. meningitidis Nm dCas9 and S. thermophilus St1 dCas9 fused to NLSs and under the control of the CMV-TetO promoter. The cognate sgRNAs Sp sgRNA, Nm sgRNA, and St1 sgRNA are under the control of the U6 promoter, and their sequences are shown below, with the mutations in red and hairpin extensions in orange. Directed by the appropriate sgRNA, different chromosomal loci are expected to become fluorescently labeled with any one of the three spectral versions of dCas9. In the diagram, such hypothetical targeted sequences are indicated by the color matching a particular dCas9/sgRNA ortholog. Credit: (c) 2015 PNAS, doi: 10.1073/pnas.1420024112 © 2015 Phys.org (Phys.org)—Is there a way to peer inside the nucleus of a living cell and see how the genes interact? After the completion of the Human Genome Project in 2001, researchers have focused on epigenetic factors, spatial orientation, and non-coding repeated sequences, all of which affect genetic regulation and function. Hanhui Ma and Thoru Pederson from University of Massachusetts Medical School have demonstrated a new technique that resolves the spatial orientation between two target genetic repeated units within a living human cell. Their work is reported in the Proceedings of the National Academy of Sciences. Ma and Pederson have done prior work labeling genes with a fluorescent protein tag using TALEs technology. However, the CRISPR/Cas9 system has proven to be the formidable approach to gene editing because it is able to target more than one genetic sequence at a time.Other gene editing systems typically require a particular endonuclease to splice a specific gene, but for this system, Cas9 is used for all sequences, allowing for multiple targets within a single cell. Furthermore, to target a sequence, either for editing or labeling, researchers can make a synthetic RNA strand, known as the guide RNA, that is complementary to the target DNA sequence. While CRISPR/Cas9 has some limiting factors, such as off-target cuts or optimizing the PAM sequence, this is a robust method for targeting multiple genes.In this experiment, Ma and Pederson used a catalytically inactive Cas9 (dCas9) endonculease to insert a fluorescent protein tag on the target sequence without causing a break in the DNA strand. Their goal was to insert two different labels that would target two different sequences. This would allow them to study the gene regions relative to each other as well as see where repeated locations occurred. Their first step was to optimize their system. They chose to target the telomeric repeat for optimization and used three known Cas9 variants for the PAM sequences, S. pyogenes, Neisseria meningitidis, and Streptococcus thermophilus which were fused to red, green, and blue fluorescent proteins, respectively. Overall, the factors that they optimized were the choice of promotor driving the expression of dCas9, the number of fluorescent proteins fused in tandem, the length of guide RNAs, the PAM sequence choice, the choice of the sequence composition of the guide RNAs, and the number of nuclear localization signals. After optimizing these parameters, they were able to successfully observe all three targets.They then tested whether two different CRISPR/Cas9 systems can simultaneously label the same sequence. They used S. pyogenes and Neisseria meningitidis systems and targeted one strand of the telomeric repeat. They identified two similar patterns showing two flourescence markers on the same genetic targets. They tested co-expression using S. pyogenes and Streptococcus thermophiles, and obtained similar results.They then tested different, repeated chromosome-specific sequences. They chose two sequences on chromosome 9 and another sequence that is localized on chromosome 13. They were able to resolve the two sequences on chromosome 9 as being approximately two micrometers apart, which corresponds to the known distance between these sequences on the physical map of chromosome 9. They were also able to resolve two sequences between two different chromosomes, 9 and 13, that were even closer in proximity than the sequences on chromosome 9.Finally, they wanted to test the resolution of their technique by choosing two sequences that are closer together on the same chromosome than their initial test with chromosome 9. They looked at two sequences on chromosome 13 that are known to be 1.9 Mbp apart from each other. They were able to resolve these using their multicolor CRISPR/Cas9 technique, and proved that it can resolve sequences that are 2.0 to 1.9 Mbp apart.These experiments were able to resolve multiple interchromosome and intrachromosome target repeated sequences using flourescent protein tags. The authors are interested in looking at repeated sequence patterns that are specific for each chromosome. However, they envision this technique eventually being used for resolving two single-copy sequences. Citation: Color-coading gene sequences in human cells (2015, March 4) retrieved 18 August 2019 from https://phys.org/news/2015-03-color-coading-gene-sequences-human-cells.html More information: “Multicolor CRISPR labeling of chromosomal loci in human cells” Hanhui Ma, PNAS, DOI: 10.1073/pnas.1420024112AbstractThe intranuclear location of genomic loci and the dynamics of these loci are important parameters for understanding the spatial and temporal regulation of gene expression. Recently it has proven possible to visualize endogenous genomic loci in live cells by the use of transcription activator-like effectors (TALEs), as well as modified versions of the bacterial immunity clustered regularly interspersed short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Here we report the design of multicolor versions of CRISPR using catalytically inactive Cas9 endonuclease (dCas9) from three bacterial orthologs. Each pair of dCas9-fluorescent proteins and cognate single-guide RNAs (sgRNAs) efficiently labeled several target loci in live human cells. Using pairs of differently colored dCas9-sgRNAs, it was possible to determine the intranuclear distance between loci on different chromosomes. In addition, the fluorescence spatial resolution between two loci on the same chromosome could be determined and related to the linear distance between them on the chromosome’s physical map, thereby permitting assessment of the DNA compaction of such regions in a live cell. Explore further End of CRISPR-CAS9 controversy 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.
Terminology associated with various cyclizations in the Diels–Alder family of 4π + 2π reactions. a, The classic example of a diene (1,3-butadiene, 1) and a dienophile (ethylene, 2) reacting to give a six-membered cyclic alkene (cyclohexene, 3). b, The absence of four hydrogen atoms gives the tetradehydro (TDDA) variant; the product is in the benzene oxidation state. c, The absence of six hydrogen atoms gives the hexadehydro Diels–Alder (HDDA) variant. d, The unprecedented pentadehydro-Diels–Alder (PDDA) reaction proceeds via an α,3-dehydrotoluene (see 12); importantly, both the HDDA and PDDA reactions result in formation of trappable reactive intermediates. e, α,3-Dehydrotoluenes have previously been generated principally by cyclization of allenyl enynes like 14. Credit: Teng Wang, et al. Nature (2016). DOI: 10.1038/nature17429 Explore further Journal information: Nature Researchers provide evidence for a non-enzymatic pathway to produce paracaseolide A © 2016 Phys.org In the current research Teng Wang, Rajasekhar Reddy Naredla, Severin K. Thompson, and Thomas R. Hoye trap an intermediate formed from the removal of five hydrogens from the typical reactants in a [4+2] Diels-Alder cycloaddition. This intermediate, called α,3-dehydrotoluene, is of interest because its oxidation state is analogous to benzyne, and like benzyne, it can be chemically trapped. This allows for functionalization at unique positions on the molecule. Their work appears in Nature.Removal of hydrogens from the diene of a [4+2] Diels-Alder cycloaddition results in either an allenyne, an unsaturated organic molecule that contains both a double and triple bond, or a diyne, a molecules with two triple bonds. In the case of a tetra-dehydro Diels-Alder reaction, in which four hydrogens are removed, the cycloaddition results in a benzene ring. In the hexa-dehydro Diels Alder reaction (HDDA), a alkyne and a diyne reaction to form a benzyne intermediate, 1, 2-dehydrobenzene. The penta-dehydro Diels Alder reaction (PDDA) involves the reaction of an allenyne an alkyne to produce α,3-dehydrotoluene as an intermediate. The benzyne intermediate from the HDDA reaction and the α,3-dehydrotoluene intermediate from the PDDA reaction are tautomers of each other, and both can be trapped using an appropriate trapping agent. Hoye’s group is the first to trap α,3-dehydrotoluene in a PDDA cyclization reaction. Hoye’s group first suspected that this intermediate occurs from a reaction they did with a particular tetrayne at room temperature in a solution of piperidine. α,3-dehydrotoluene has been observed as a result of Myers-Saito cyclization reaction, but prior to this study, has not been isolated as part of a formal cycloaddition reaction. They found that differences between the intermediates in the HDDA and PDDA reaction has to do with a base-promoted rate-limiting step in the PDDA reaction. Their initial reaction showed that the tetrayne undergoes a piperdine-catalyzed isomerization to produce an allenyne. This then undergoes a PDDA cyclization reaction whose intermediate can be trapped with piperidine, a secondary amine. This mechanism can be generalized to a base-promoted isomerization to produce an allenyne, followed by trapping the intermediate with a protic trapping agent. Hoye’s group looked at other primary and secondary amines as well as oxygen-based nucleophiles such as methanol and water, and found that all of them served as good trapping agents for the α,3-dehydrotoluene intermediate. Hoye’s group also found that the PDDA cyclization reaction worked with a nitrile in place of the alkyne on the allenyne reactant. Furthermore, the PDDA cyclization worked with electron withdrawing groups on the nitrile, and the intermediate can be trapped using the same trapping agents as with the allenyne reaction. Notably, nitriles to do not undergo cyclization in HDDA reactions, therefore, its ability to cyclize in PDDA reactions allows for greater diversity in the types of products that can be made from these reactions.This newly discovered reaction mechanism and isolation of its intermediate allows for the synthesis of several types of organic molecules that would be of interest, including pyridine products. Additionally, it provides insight into the mechanistic differences between the hexa-dehydro Diels Alder reaction and the penta-dehydro Diels Alder reaction, which may be exploited for further studies on cyclization reactions. 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: Teng Wang et al. The pentadehydro-Diels–Alder reaction, Nature (2016). DOI: 10.1038/nature17429AbstractIn the classic Diels–Alder [4 + 2] cycloaddition reaction, the overall degree of unsaturation (or oxidation state) of the 4π (diene) and 2π (dienophile) pairs of reactants dictates the oxidation state of the newly formed six-membered carbocycle. For example, in the classic Diels–Alder reaction, butadiene and ethylene combine to produce cyclohexene. More recent developments include variants in which the number of hydrogen atoms in the reactant pair and in the resulting product is reduced by, for example, four in the tetradehydro-Diels–Alder (TDDA) and by six in the hexadehydro-Diels–Alder (HDDA) reactions. Any oxidation state higher than tetradehydro (that is, lacking more than four hydrogens) leads to the production of a reactive intermediate that is more highly oxidized than benzene. This increases the power of the overall process substantially, because trapping of the reactive intermediate can be used to increase the structural complexity of the final product in a controllable and versatile manner. Here we report an unprecedented overall 4π + 2π cycloaddition reaction that generates a different, highly reactive intermediate known as an α,3-dehydrotoluene. This species is in the same oxidation state as a benzyne. Like benzynes, α,3-dehydrotoluenes can be captured by various trapping agents to produce structurally diverse products that are complementary to those arising from the HDDA process. We call this new cycloisomerization process a pentadehydro-Diels–Alder (PDDA) reaction—a nomenclature chosen for chemical taxonomic reasons rather than mechanistic ones. In addition to alkynes, nitriles (RC≡N), although non-participants in aza-HDDA reactions, readily function as the 2π component in PDDA cyclizations to produce, via trapping of the α,3-(5-aza)dehydrotoluene intermediates, pyridine-containing products. (Phys.org)—The Diels-Alder reaction is a mainstay in organic chemistry. The reaction traditionally involves a diene and a dienophile. The diene has four carbons that are sp2 hybridized to form pi bonds. The dienophile has two sp2 hybridized carbons. The diene and dienophile undergo a cycloaddition reaction to form a cyclohexene. This reaction can be tweaked to make six-membered rings with a higher oxidation state by removing hydrogens from the reactants to make sp hybridized carbons. For example, rather than an alkene and a diene reacting, the reactants could be an alkyne and an allenyne. Citation: A new Diels-Alder reaction (2016, April 27) retrieved 18 August 2019 from https://phys.org/news/2016-04-diels-alder-reaction.html
Citation: Astronomers detect a fast rotating group of stars in our galaxy (2016, November 16) retrieved 18 August 2019 from https://phys.org/news/2016-11-astronomers-fast-rotating-group-stars.html Explore further The discovery was made by a team of researchers led by Jason Hunt of the University College London, U.K. They have combed through the Tycho-Gaia astrometric solution (TGAS) data included in data release 1 (DR1) from ESA’s Gaia satellite. The spacecraft is completing a survey of one billion stars in our galaxy and local galactic neighborhood, measuring their positions with an accuracy of microarcseconds.”We wanted to examine the speed with which the stars rotate around the Galaxy, and for that, we need velocity in three directions. We have never been able to explore local galactic dynamics in such detail because very few stars have had reliable distance estimates. This first data release provides distance estimates for around 2 million stars in the solar neighbourhood, and the next data release will have over one billion! This is a substantial improvement on the previous mission, Hipparcos, which provided measurements for about 150,000 stars,” Hunt told Phys.org.He noted that this fast rotating group of stars was difficult to pick out because Gaia DR1 only provides velocities in two directions across the sky, and not line-of-sight velocity toward and away from us. However, by looking directly toward or away from the galactic center, it was possible to approximate the rotation velocity.The astronomers calculated that the newly detected group of stars is rotating faster than the sun by about 20 km s−1. Moreover, they found that the stars in this fast rotating group are rotating significantly faster than the mean rotation of the stars.Trying to explain these distinct velocities, the team assumed that they are caused by one of the two major spiral arms of the Milky Way – the Perseus Arm. The results indicate that stars which are behind the spiral arm, and at the pericenter of their orbits, experience an extended period of acceleration from the gravitational potential of the Perseus Arm.”This extended period of acceleration causes them to move significantly faster than the other stars. We also know that this will either occur at one point along the spiral arm if the arm moves as a wave with a constant pattern speed through the disc, or it will occur all along the arm if the spiral arm moves with the same velocity as the stars, which is predicted by computational models based on the gravitational interaction of stars, called N-body simulations,” Hunt said.The team’s research supports both of the competing theories of spiral arm dynamics mentioned by Hunt. However, it favours slightly the theory seen in N-body simulations in which the arm moves with the same speed as the stars, because the scientists found that the feature remains unchanged at increasing distance from the sun.”The quantity of data and the observational errors involved mean we cannot say for certain whether this is the case. We cannot observe further along the arm with the current data,” Hunt noted.The scientists hope that data shedding some new light on this case could be delivered by Gaia’s data release 2 (DR2), scheduled to be published in November 2017. The increased quantity and quality of data in DR2 will allow the researchers to observe further along the spiral arm and determine whether this group is present along the entire spiral arm, or present towards the galactic anti-center.”If it’s present all along the arm it will be strong evidence for the type of transient reforming spiral arm created in the models, and if it is only present just outside the solar radius where we observed it in this work, it will be strong evidence for the theory that spiral arms travel as density waves through the disc,” Hunt concluded. © 2016 Phys.org Virtual Milky Way Barred Spiral Milky Way. Illustration Credit: R. Hurt (SSC), JPL-Caltech, NASA (Phys.org)—European astronomers have spotted a group of stars with high rotation velocity residing outside the solar radius in our Milky Way galaxy. According to a paper published Nov. 2 on arXiv.org, this group, which moves significantly faster than the majority of other stars, could provide essential information about stellar dynamics. More information: Fast rotating group of stars observed in Gaia TGAS: a signature driven by the Perseus arm? arXiv:1611.00761 [astro-ph.GA] arxiv.org/abs/1611.00761 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.
To explain the unconventional phenomenon, they proposed a gravity-driven assembly model where the salt-initiated aggregates grew gradually and settled down due to gravity to concentrate and evolve into a hydrogel at the bottom. The scientists supported this model using UV-VIS absorption spectra to visualize the entire process of gelation. Since hydrogels can self-repair, the materials displayed promising self-healing properties in diverse environments without external energy input. Du et al. conducted time-lapse characterization studies to test the extremely fast formation of aggregates with multiscale microstructures. Additionally, they competed time-lapse transmission electron microscopy (TEM) and in situ optical tests to reveal the evolutionary footprints of 3-D networks at different scales. Using the analytical techniques, the scientists observed the formation of gold nanoparticle (NP) dimers, followed by their gradual axial growth to form nanowire-structured networks during the sol-gel process of NMF fabrication. The scientists showed how the experimental outcomes varied the form (gel to powder) and color (black to brown) of the ions, to strongly correlate to the salting-out effects as dictated by the Hofmeister series (a classification of ions according to their ability to salt-out or salt-in proteins). They used time-lapse TEM imaging to further reveal the growth mode of NPs and the ligament size variation during network development and proposed a possible mechanism during NMF formation via the sol-gel process. Accordingly; The original NPs approached each other instantly on the addition of salts due to electrostatic screening.The ligands then partially stripped away from the NPs by oppositely charged cationsFollowed by the generation of NPs to form aggregates driven by the raised surface energy of uncapped NPsThe aggregates repeated the process across axial and radial directions For the aggregates to finally settle by gravity-driven sedimentation to form hydrogel at the bottom.The ability to systematically manipulate the ligament size and corresponding physical properties of NMAs was not previously realized. As a result, Du et al. deeply studied the gelation process to unlock specific ion effects and strategies of manipulation. For this, they deliberately selected specific salts (NH4SCN, NH4NO3 and KCl) as initiators. , Nature Analysis of the overall gelation process of gold NPs. (A) Digital photos of the gel preparation process. (B) Schematic demonstration of the gelation process and a corresponding force analysis. (C) The gradient distribution during the gelation characterized by ultraviolet-visible (UV-vis) absorption spectra. a.u., arbitrary units. (D) Several pieces of as-prepared hydrogels can assemble to one piece. (E to H) Time-lapse (E) UV-vis absorption spectra, (F) hydrodynamic size, (G) transmission electron microscopy (TEM), and (H) optical microscopy characterization during gelation. The inset in (E) shows the time-lapse UV-vis absorption evolution at 510 nm, which was recorded during the first minute upon reaction. (Photo credit: Ran Du.) Credit: Science Advances, doi: 10.1126/sciadv.aaw4590 During electrocatalysis of alcohol electro-oxidation reactions, the scientists showed that Au-Pd and Au-Pd-Pt aerogels performed substantially better compared with commercial Pd/C or Pt/C catalysts. The results also showed higher performance compared to previously reported NMAs such as Pd-Cu, Pd-Ni and Au-Ag-Pd aerogels. However, the scientists recorded considerable current decay for the Au-Pd and Au-Pd-Pt aerogels during long-term tests; a common issue for commercial catalysts. The optimized electrocatalytic potential will allow aerogels to function as anodic catalysts in various fuel cells and enhance electrical conductivity to facilitate efficient electron transfer during electrocatalysis.In this way, Du and co-workers developed a specific ion-directed gelation strategy to rapidly manufacture and flexibly manipulate NMAs at room temperature from a nanoparticle (NP) solution. Using the experimental results and DFT calculations they proposed an overall mechanism for the sol-gel process. The present work provides a new concept and straightforward approach to fabricate different NMAs. The work will pave the way forward for materials scientists to design on-target, versatile NMFs for a variety of applications using structure-performance relationships to form on-demand desirable properties. The NMFs exhibited superior performance as programmable self-propulsion devices, which the scientists proved using electrocatalytic alcohol oxidation reactions. The study provided a conceptually new approach to engineer and manipulate NMFs to provide an overall framework and understand the mechanisms of gelation. The work will pave the way forward to design on-target NMFs to investigate structural performance relationships for a variety of applications. Functional porous materials are an interesting topic at the cutting edge of materials science, combining porous structures and versatile compositions for multidisciplinary applications. Noble metal foams (NMFs) are a rising star in the foam family and have gained tremendous attention during their debut. The addition of noble metals into 3-D gel networks has enhanced NMFs with a variety of potential applications but their development is still in the early stages with limited fabrication strategies and lesser understood structural properties that cannot be well manipulated.Typically, NMFs are engineered using four classes of methods, which include:DealloyingTemplatingDirect freeze-drying, and The Sol-gel process.Of these, the sol-gel process has substantially produced nanostructured and high surface areas for NMFs under mild conditions to become a popular synthetic strategy. Nevertheless, the sol-gel process is at an infant stage with numerous mysteries surrounding the process; constraining its exploration to understand gelation mechanisms for on-demand manipulation. Analysis of the specific ion effects on the gelation behavior and ligament size. (A) Summary of the status of gels induced by different ions. The inverted triangle and the diffused circle indicated the gel and powder, and black and brown indicated the color of the products. (B) Zeta potential upon reaction and (C) dh versus the color and form of products. The data were obtained by averaging detailed values from the inset diagram. (D) The low-threshold gelation concentration of salts (cs) versus the used cations. (E) The ligament size (averaged over the anions used as in the inset diagram) of as-synthesized gold aggregates versus cations. (F) Time-lapse ligament size evolution of gold aggregates induced by three typical salts. (G) Proposed mechanism for gel formation. Credit: Science Advances, doi: 10.1126/sciadv.aaw4590 Noble metal foams (NMFs) are a new class of functional materials that contain both noble metals and monolithic porous materials for impressive multi prospects in materials science and multidisciplinary fields. In a recent study now published on Science Advances, Ran Du and a team of interdisciplinary researchers in Physical Chemistry, Materials Engineering and Physics developed highly tunable NMFs by activating specific ion effects to produce a variety of single/alloy aerogels. The new materials contained adjustable composition—with gold (Au), silver (Ag), palladium (Pd) and platinum (Pt)—and special morphologies. In the present work, Du et al. presented a method for rapid fabrication and flexible manipulation of NMFs by activating and designing specific ion effects. For this, they experimentally studied in depth gelation processes alongside complementary DFT calculations to outline the overall reaction process. Du et al. realized versatile compositions with multiple alloys, ligament sizes, specific surface areas and spatial element distribution during materials synthesis. The method and the enormous ion library developed in the work will offer unprecedented opportunities to manipulate NMFs and extend to diverse colloidal solution systems, as demonstrated with electrocatalytic alcohol oxidation and a dark-to-shining chemical reaction. More information: Ran Du et al. Specific ion effects directed noble metal aerogels: Versatile manipulation for electrocatalysis and beyond, Science Advances (2019). DOI: 10.1126/sciadv.aaw4590 A. G. Slater et al. Function-led design of new porous materials, Science (2015). DOI: 10.1126/science.aaa8075 S. S. KISTLER. Coherent Expanded Aerogels and Jellies, Nature (2008). DOI: 10.1038/127741a0 Versatile manipulation of NMAs. (A) Tailor the ligament size of gold gels by introducing NaOH/NaCl hybrid salts. (B) Ligament size of gold aerogels from different references of studies previously conducted. (C) The ligament size variation with Au/Pd ratio. (D) Ligament size modulation of Au-Pd, Au-Pt, Pd, and Ag gels using different salts. (E) The dependence of density, Brunauer-Emmett-Teller (BET) surface area, and Barrett–Joyner–Halenda (BJH) pore volume of aerogels versus ligament size. (F) Demonstration of the size-dependent mechanical properties of aerogels by bending with a tweezer. From left to right are Au-Ag-NH4F (5.8 ± 0.7 nm), Au-NH4SCN (8.9 ± 2.5 nm), Au-NH4NO3 (18.2 ± 4.0 nm), and Au-NaCl (64.0 ± 13.3 nm), respectively. (G to I) STEM–energy-dispersive x-ray spectroscopy (EDX) of three alloy gels with (G) homogeneous and (H and I) core-shell architectures. Credit: Science Advances, doi: 10.1126/sciadv.aaw4590 © 2019 Science X Network Citation: Specific ion effects directed noble metal aerogels (2019, June 5) retrieved 18 August 2019 from https://phys.org/news/2019-06-specific-ion-effects-noble-metal.html Demonstration of black gels, brown gels, and black powders as prepared in the study.Credit: Science Advances, doi: 10.1126/sciadv.aaw4590 Hard carbon nanofiber aerogel becomes superelastic Du et al. first added the gold nanoparticles (NP) solution with specific salts and grounded it from 4 to 12 hours to yield the hydrogel, then freeze-dried it further to obtain the corresponding aerogel. The NMFs indicated a robust gelation capacity and completely eliminated the need for expensive concentration processes. The approach used by the scientists uniquely allowed for rapid gelation of the metal precursors at low concentrations and ambient temperature. Journal information: Science Advances Demonstration of pressing original aerogels into shining materials. Credit: Science Advances, doi: 10.1126/sciadv.aaw4590 , Science They observed a brown color for the KCl-induced aerogel, while two other aerogels with smaller ligament sizes appeared black due to strong light absorption / scattering between nanosized domains. Changing the ligament size also changed their density, specific surface area and pore volume. The scientists showed improved outcomes for ligament size and additional properties by using hybrid-salts in the experimental setup. Based on the proposed gelation mechanism, they expanded the system to include noble metals and their alloys (Ag, Pd, and Pt). The present work provided set guidelines to engineer the physical parameters of NMAs. This is an important outcome since the physical and mechanical properties of NMAs currently remain a great challenge to be realized. The straightforward, synthetic approach introduced in the present work provided a variety of bimetallic and trimetallic gels with well defined, tunable core-shell architecture.Since metals are remarkably ductile, the scientists induced a dark-to-shining transition by manually rearranging the NMAs from the millimeter to micrometer scale to regain a metallic gloss with nanostructured “mirror surfaces.” Du et al. welded together different aerogels to form macroscopic heterostructures and the extraordinary plasticity of the materials allowed the scientists to arbitrarily shape and encase the NMAs within elastomers for use as flexible conductors. Using catalytic oxygen evolution they maintained the different NMAs as an alternative to the expensive Platinum-based conductors. Explore further 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. 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For many of us—no matter where we work or what we do—nothing feels as good as success. And for many of us, nothing is more harmful to our growth and development To understand why this is, compare success to failure. Companies tell their employees over and over again to embrace your failures, to ask yourselves what went wrong and to take advantage of all the learning opportunities that failure affords. What a missed opportunity that is. In fact, it almost guarantees that success will eventually breed not more success, but failure. But when it comes to success, companies rarely feel the urge to stop and see what they can learn from their experience, and what they may want to change. Rather, the instinct is to assume that if they succeeded, all is good with the world. What did we do right? Everything. What did we do wrong? Nothing. With that in mind, here are guidelines I’ve culled from my research for the best ways to put successes under a microscope—and make future successes a lot more likely. Read the whole story: The Wall Street Journal
Kolkata: Civic body officials of South Dum Dum Municipality led by chairman Panchu Gopal Roy on Friday raided a prawn processing unit at ward 21.”We had received a source information about some irregularities in the prawns that are stored at the unit. Accordingly, we conducted a raid and have found that some sort of reddish colour was added to the prawns. We are not ruling out the fact that it may be some sort of preservative that was mixed with it. We have sent it for examination at our government laboratory for examination,” chairman said. Also Read – Heavy rain hits traffic, flightsThe team from the municipality also conducted a drive at a multi shopping complex which has a food court. Sources in the health department of the municipality said samples were collected from as many as 12 restaurants that have been sent for tests. “Apparently our officers have stumbled upon irregularities in the way they deal with food. French fries have been found stored in refrigerators. The meat at some of the restaurants was also emitting a foul smell. We have also found that leftover food was stored in refrigerator,” Debasish Banerjee, chairman in council (public health ) said.Customers in some of the restaurants also c omplained about bad quality food and welcomed the civic body’s drive to ensure quality of food. “We are waiting for the reports and if we found any irregularity we will take strong action against the offenders as per law,” Roy said.