Safe Nuclear Power and Green Hydrogen Fuel

first_img Reactor Interior – pebbles in red: www.eskom.co.za/ nuclear_energy/ pebble_bed/ pebble_bed.html But in other countries, they’ve been able to make it work. In France, for instance, about 75 percent of electricity is generated from nuclear power. Worldwide, it provides 17% of our energy. The US has not brought a new plant online since 1996 yet still generates 788.6 billion kilowatt-hours (KWh) yearly – almost 20% of the US total – accident free.Nuclear power is like a handgun. It’s the people handling it who are dangerous. But there is one big difference: with a handgun, you shoot a few people at most. A reactor accident could wipe several hundred square miles – permanently.But all technologies start out crawling before they can walk or even run. The nuclear scientists have been working on the safety problems and already may have solved them.Danger aside, what makes nuclear power attractive? It’s competitive or cheaper than other forms of power generation. It’s easy to build compact plants that generate hundreds if not thousands of megawatts – something wind and solar can never hope to match. See the chart below to compare energy generation costs. SLAC makes ‘electron camera,’ a world-class tool for ultrafast science, available to scientists worldwide Compared with coal, still used to produce 50% of the US electricity needs, nuclear is clean. It creates no greenhouse gases. Its waste, although highly toxic, is compact and when handled correctly, safe.Uranium, the fuel reactors use, is widely available in the continental US and Canada. Australia has the largest known reserves. This makes it unlikely rouge states can affect supply. Stable supply means lower long-term costs – especially when compared with oil and gas fired plants which are now producing about 20% of US electricity.Reactor designs such as the Canadian CANDU can be very safe and less expensive to build than most reactors in use today. One drawback to this design, unfortunately, is its ability to produce weapons grade plutonium as a byproduct. On the plus side, it can use unenriched uranium – about .07% uranium 235. Regular plants require between 2% and 7% uranium 235 in reactor fuel to run properly. Physicists and engineers at Beijing’s Tsinghua University have made the first great leap forward in a quarter century, building a new nuclear power facility: a pebble-bed reactor (PBR) – sometimes also known as a Pebble Bed Modular Reactor (PBMR). This reactor is small enough to be assembled from mass-produced parts and cheap enough for emerging economies. Its safety is a matter of physics, not operator skill or reinforced concrete. This reactor is meltdown-proof. PBR from www.pbmr.co.za What makes it so safe is the fuel: instead of conventional fuel rods made of enriched uranium, PBRs use small, pyrolytic graphite coated pebbles with uranium cores. As a PBR reactor gets hotter, the rapid motion of atoms in the fuel decreases probability of neutron capture by U-235 atoms. This effect is known as Doppler Broadening. Nuclei of heated uranium move more rapidly in random directions generating a wider range of neutron speeds. U-238, the isotope which makes up most of the uranium in the reactor, is much more likely to absorb the faster moving neutrons. This reduces the number of neutrons available to spark U-235 fission. This, in turn, lowers heat output. This built-in negative feedback places a temperature limit on the fuel without operator intervention.PBRs use high-pressure helium gas, not water, for cooling. Reactors have been “run dry” – without cooling gas. Result: they simply stabilize at a given temperature – lower than the pebbles’ shell melting point. No meltdown can occur. 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. Citation: Safe Nuclear Power and Green Hydrogen Fuel (2005, December 11) retrieved 18 August 2019 from https://phys.org/news/2005-12-safe-nuclear-power-green-hydrogen.html Fuel Spheres: www.eskom.co.za/nuclear_energy/pebble_bed/pebble_bed.htmlcenter_img Internal functioning with cooling diagram: www.eskom.co.za/nuclear_energy/pebble_bed/pebble_bed.html Image source: http://www.uic.com.au/nip08.htm Explore further Nuclear power is being shunned. It’s not surprising, after the serious accident at Chernobyl in 1986 that made the Russian city’s name synonymous with disaster. The potential exists for more of the same and many countries have given up on nuclear power altogether. Each PBR would produce between 100 and 200 MW – small, in comparison to light and heavy water reactors which typically product around 1,000 MW. But they could easily be scaled up by adding reactors.Ten PBR reactors producing 1,100 MW would occupy an area of no more than three football fields. Each PBR could serve about 30,000 to 40,000 homes.Control rooms – much simpler than standard ones – would have a few PCs and extra monitors instead of banks of valves and dials. Each control room could monitor and manage up to 10 reactors.One of the key features to this technology, especially important in China where energy demand is exploding, is its modular nature. While conventional reactors in operation today are all one of a kind – although many are based on the same designs – PBR reactors could de built with standard rail-movable components. When a new power plant is needed, they simply load the parts on a train with a construction crew and can have it delivering power in short order. Traditional plants in the US were sunk principally by long construction times and cost overruns, not environmental regulations.Nuclear waste disposal has become a hot-button issue. Standard nuclear waste is very radioactive for 10,000 years or more. It must be transported to and stored in special containment facilities – normally underground. It can also be reprocessed but this is costly and technically difficult. There are only 3 reprocessing facilities worldwide: Thorpe in England, Cogema in France and Myakrt1 Chemical Combine in Russia. Far away from most of the world that needs clean, inexpensive power.Fuel pebbles have 4 caps of containment built in. Many authorities consider pebbled radioactive waste stable enough it can be safely disposed of in geological storage – without any additional shielding or protection. Even in tests where pebbles were exposed to very high heat without coolant for long periods, they showed no outward damage. If one did manage to break a pebble it would only release one tiny (0.05mm) uranium dioxide particle. This particle is too heavy to be wind borne and so could not be blown into other areas like the fallout from the explosion at Chernobyl.PBR proponents state they plan to store all waste products on the plant site – avoiding costly and dangerous radioactive material movement.Even with the long term radioactivity and highly toxic nature of nuclear waste, some environmentalists are voicing support for nuclear energy.James Lovelock, well known green activist and creator of the Gaia hypothesis that Earth is a single self-regulating organism, published a plea to phase out fossil fuels. Nuclear power, he argued, is the best short term hope for averting climatic catastrophe:”Opposition to nuclear energy is based on irrational fear fed by Hollywood-style fiction, the Green lobbies, and the media. … Even if they were right about its dangers – and they are not – its worldwide use as our main source of energy would pose an insignificant threat compared with the dangers of intolerable and lethal heat waves and sea levels rising to drown every coastal city of the world. We have no time to experiment with visionary energy sources; civilization is in imminent danger and has to use nuclear, the one safe, available energy source, now, or suffer the pain soon to be inflicted by our outraged planet.” – From the London Independent – May, 2004Nuclear power, shunned after so many years, may be ready for resurgence. For some countries, like China, it may offer the only hope to meet its energy needs of its billion plus population in the 21st century. Indeed, they already have the first 10MW test reactor up and running.By Philip Dunn, Copyright 2005 PhysOrg.com The high-temperature gas design also has a silver lining – it can produce hydrogen. Think about that – fuel cell vehicles need expensive-to-produce hydrogen to run on – this reactor could make hydrogen as a byproduct.Generation of hydrogen has been the biggest stumbling block to it adoption as a clean fuel. Hydrogen, found primarily in water, is expensive to extract as a gas. While the technical problems of handling, storage and use as fuel are largely solved, the high energy cost to produce hydrogen has made it an energy transport medium, not a source. These new reactors run at high temperatures which are perfect for cracking abundant water or helium gas into hydrogen which can then be used as a green fuel – burning hydrogen just produces water vapor.PBRs could produce cheap hydrogen that could be piped to areas of need or used in the local communities.Plant sites are much smaller than traditional nuclear power plants. Their modular design allows for smaller plants that can grow with needs. A single PBR reactor would consist of one main building covering an area of about 1,300 square meters – less than half a football field. It would be about 42m high (6 stories), some of it below ground level. Billion dollar steel reinforced concrete containment vessels are not required – any coolant leak would be in the form of nonradioactive helium gas which would quickly disperse with out causing any ill effects. South Africa may have the most modern PBR on the drawing board. With the help of German scientists – acknowledged leaders in the field – they have planned to build several reactors within the next five years. Images in this article come from their design.The reactor core is a bin of uranium fuel pebbles. Each tennis ball-sized pebble is rotated and/or checked for reactivity by removing them from the bottom of the funnel shaped reactor core. Spent pebbles are replaced by adding new ones at the top of the stack. Used ones that are still reactive also go to the top of the bin. The reactor can be re-fueled without stopping power production – not possible in conventional rod reactors which requires a full shut down.Pebbles, because of their round nature, allow the cooling gas to be introduced at the bottom and pass freely through the stack. The heated gas is removed to perform work like spinning a turbine to generate electricity then recycled in a closed loop back to the reactor core.PBRs use helium, which has high thermal conductivity and inertness (read: fireproof and noncorrosive) for cooling. This makes them more efficient at capturing heat energy from nuclear reactions than standard reactor designs. The ratio of electrical output to thermal output is about 50%.last_img read more

Read More →

Scientists interpret physics behind invisibility cloaks

first_img Explore further A direct current (DC) remote cloak to hide arbitrary objects When a polarized plane wave is incident upon an ideal spherical cloak, the object behind the cloak is completely hidden, as shown in this figure (wave arrows from behind pass through the cloak to appear in front). Credit: Chen, et al. ©2007 PRL. “The cloak is both anisotropic and inhomogeneous: all of the components in the permittivity and permeability tensor are functions of the radius, which implies that the perfect invisibility cloak is very difficult to design,” Chen explained. “If we introduce a specific type of loss both in a spherical cloak and a cylindrical cloak, only the spherical cloak exhibits a zero backscattering, which indicates only the spherical cloak can still be rendered invisible with a monostatic (transmitter and receiver in the same location) detection. This is because the impedance of the spherical cloak is still matched to the free space in this particular loss case.”Because they have less stringent requirements, imperfect cloaks may offer a more realistic alternative for engineers. Although imperfect cloaks have non-zero scattering, the objects they cloak can still appear isolated from the outside field under certain specific conditions and the incident fields cannot penetrate into the hidden object. Besides, for an imperfect cloak with matched impedance, it can still be rendered invisible with monostatic detection, which is most widely used in current radar.“For a monostatic detection, no reflection wave will be received by the detector if the imperfect cloak has a matched impedance with the free space,” Chen explained. “Therefore, the imperfect cloak, even with its parameters deviated far from the ideal parameters, still can be made completely invisible with the monostatic detection as long as it satisfied the impedance requirement.”Since almost all current radars belong to the monostatic class, Chen explained that this research can offer a more realistic alternative for engineers. In the future, applications of invisible cloaks could include military uses such as making planes and weapons invisible to radar, enabling the possibility of looking out walls as if they were windows, and hiding ugly factories for aesthetic reasons.“The effectiveness of the cloak based on the analytical solutions of the electromagnetic wave interactions with metamaterial cloaks (ideal or non-ideal) can be quantitatively provided,” Chen said. “Our research work therefore provides a new way for the cloak design and to qualify the effectiveness or performance of a non-ideal cloak.”Citation: Chen, Hongsheng, Wu, Bae-Ian, Zhang, Baile, and Kong, Jin Au. “Electromagnetic Wave Interactions with a Metamaterial Cloak.” Physical Review Letters 99, 063903 (2007).Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Hongsheng Chen, Bae-Ian Wu, Baile Zhang, and Jin Au Kong have published their research on invisibility cloaks in a recent issue of Physical Review Letters. The group analytically demonstrated how electromagnetic waves interact with invisibility cloaks made of metamaterials, an interaction that is often different from conventional scattering with regular particles. Their findings will hopefully be useful for cloak design and applications, an exciting research area that is still in its early stages.“When an electromagnetic wave is incident onto a conventional sphere, part of the radiation will be scattered in all directions; while for a metamaterial cloak, the incident wave will smoothly pass through the cloak undeflected,” Chen explained to PhysOrg.com. “It is very interesting that a perfect metamaterial cloak shows no reflection or absorption but rather allows the Poynting power to bypass the hidden object. Our research also shows that the Poynting power inside of the cloak is not uniform: when close to the inner boundary of the cloak, the power flow density is close to zero, while near the outer boundary of the cloak, the power flow density becomes large.”The first invisible cloak made of metamaterials was created last year by Duke University researchers Shurig et al. Metamaterials, which are composed of a man-made matrix of tiny metal wires and loops that control electromagnetic waves, can create an area in space where no electromagnetic waves propagate. The light waves flow around the cloaked object like water in a creek flows around a rock, appearing on the other side in such a way that an observer can’t tell that the waves flowed around an obstacle. In the first experimental trial, the cloak hid the concealed object from the electromagnetic microwaves in two dimensions. Chen and his colleagues wanted to know if perfect invisibility could be achieved under any wavelength. The scientists explained that perfect invisibility is achieved when the scattering cross section is zero, which indicates that the cloak exhibits zero scattering. The group found that the parameters for a perfect cloak are very difficult to realize, and that when some specific type of loss is included, the three dimensional spherical cloak wrapped around a hidden object exhibits zero backscattering while a two dimensional cylindrical cloak does not.center_img Is a perfect invisible cloak theoretically possible? Are there certain wavelengths—such as those in the visible spectrum—that can’t be made invisible? How will using imperfect materials affect the performance of a cloak? Scientists from Zhejiang University and MIT have recently analyzed the physics behind invisibility cloaks in an attempt to answer some of these questions. 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. Citation: Scientists interpret physics behind invisibility cloaks (2007, August 22) retrieved 18 August 2019 from https://phys.org/news/2007-08-scientists-physics-invisibility-cloaks.htmllast_img read more

Read More →

Simulations show a single photon can simultaneously excite two atoms

first_img © 2016 Phys.org Journal information: Physical Review Letters Scientists have known for several years that it is possible to have a single atom absorb two photons, causing it to move to a higher energy state. The process has actually been observed many times and is now used in microscopy and spectroscopy—its reverse, extracting the two photons from a single atom, has also been used as a means for producing entangled photons. In this new effort, the researchers wanted to know if the same would hold true for causing a single photon to be absorbed by two different atoms—theory has already suggested it should be possible.To find out, the team created a simulation in which two atoms were held in place by mirrors inside of a chamber—creating a virtual optical cavity. They reasoned that the size of the cavity should be based on the frequency and wavelength of the photon that would be introduced (i.e. it should be double that of the photon). They then introduced the photon and found that in such a circumstance, both atoms were able to absorb the photon—each grabbing half of its energy—and moving into a higher energy state. And because the process could be reversed—the two atoms together producing a single photon, the team believes it might be possible to use the phenomenon in a quantum system—one of the atoms would theoretically serve as a qubit, carrying information. To give up its information, the qubit would move the information to the cavity where the second atom could be used to control transmission.The researchers found that the simulation worked for three atoms and one photon, as well—the energy from the photon was equally divided between the atoms. Sharing the limelight. Two or more atoms in an optical cavity can absorb a single photon, according to theory. The cavity allows standing light waves of a single frequency (red glow), which can be limited to one photon. Credit: APS/Joan Tycko/via Physics, 9, 83. Explore further , arXiv More information: Luigi Garziano et al. One Photon Can Simultaneously Excite Two or More Atoms, Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.117.043601 , On Arxiv: https://arxiv.org/abs/1601.00886ABSTRACTWe consider two separate atoms interacting with a single-mode optical or microwave resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between one photon and two atoms, via intermediate virtual states connected by counterrotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with a probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission process can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems. Researchers discover a way to avoid decoherence in a quantum system Citation: Simulations show a single photon can simultaneously excite two atoms (2016, August 5) retrieved 18 August 2019 from https://phys.org/news/2016-08-simulations-photon-simultaneously-atoms.html (Phys.org)—A small team of researchers with affiliations to institutions in Italy, Japan and the U.S. has created a simulation that suggests that it should be possible for a single photon to simultaneously excite two atoms. In their paper published in the open access journal Physical Review Letters, the team describes the process leading to their simulation, what it showed and why they believe their findings have applications in quantum computers. 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

Read More →

Therapeuticsonachip TOC Manufacturing synthetic proteins for pointofcare therapeutics

first_img In a recent study published in Microsystems & Nanoengineering, Travis W. Murphy and co-workers at the Departments of Chemical and Biological Systems Engineering at Virginia Tech developed a cost-effective, point-of-care synthetic and purification platform for protein engineering. They built an integrated microfluidics “Therapeutics-on-a-Chip (TOC)” device for cell-free, therapeutic protein synthesis and therapeutic protein purification in a single setup.The ability to synthetize therapeutic proteins in a point-of-care setting, can rapidly decrease costs of storage and transportation during global distribution in resource-poor regions and contribute to the concept of frugal science. A majority of proteins are currently produced using cell culture systems such as the recombinant Escherichia coli, yeast, mammalian cells and plant cells for large-scale manufacture, after which they are globally distributed from centralized foundries. However, the limited half-life of these synthetic proteins requires low temperature storage and shipment facilities that are challenging for patients living in remote and low-resource regions. In the present work, Murphy et al. first demonstrated the working principles of the device by expressing and purifying a reporter protein – green fluorescent protein. Followed by the use of TOC to produce cecropin B – an antimicrobial peptide widely used to control biofilm diseases. The scientists successfully synthesized and purified cecropin B to produce a concentration of 63 ng/µL in six hours, with a purity of 92 percent, followed by confirming its antimicrobial properties with a growth inhibition assay. The TOC technology provides a new platform for point-of-care protein synthesis and purification for accessible clinical therapeutics. The state-of-the-art devices presently in use for point-of-use protein synthesis includes a refrigerator-sized system that spans a two-day production-purification cycle to manufacture 800 doses of a drug per day. Yet the capital cost associated with such a system is not feasible in the developing world, where the need for speedy production of mass therapeutics for distribution outweighs mass therapeutics production for long term storage. In the TOC system developed by Murphy et al. the scientists accomplished point-of-care synthesis and purification of therapeutic proteins using a cell-free protein synthesis (CFPS) process. In this system, recombinant proteins were expressed without the use of living cells, suited for point-of-care production, where lyophilized starting materials could remain stable during storage across a broad temperature range. Protein purification in a microfluidic chamber. a) A microscopic image of the purification module. b) Overview of the purification procedure (including bead loading, bed formation, protein adsorption, washing, and elution) by three different workflows. Workflow 1 uses flow adsorption and washing steps. Workflow 2 uses flow adsorption and oscillatory washing. Workflow 3 uses oscillatory adsorption and washing. Dark blue denotes a closed valve, where transparency denotes an open valve. c) SDS-PAGE of GFP purified by the purification chip. M (Marker); D (Depleted): CFPS reaction mix after bead absorption; R (Removed): removed contaminates in the purification buffer; P (Product): purified GFP in the elution buffer. d) The purification step optimization. Optimization was conducted by examining 4 conditions. (1) Ni-NTA bead volume of 5 or 8 µl; (2) 0.5% Tween-20 added into purification and elution buffers. (3) Different workflows. (4) Different oscillatory adsorption times. Credit: Microsystems & Nanoengineering, doi: 10.1038/s41378-019-0051-8 a) A microscopic image of the synthesis module. b) The steps for synthesis: start of synthesis and steady state synthesis. c Western blotting of GFP produced in the CFPS system and the protein yield with different concentrations of the plasmid template. Mouse 6 × His tag monoclonal primary antibody and HRP-conjugated goat anti-mouse IgG (H + L) secondary antibody were used to detect the target protein. Concentrations listed are the concentrations in the final reaction volume. Credit: Microsystems & Nanoengineering, doi: 10.1038/s41378-019-0051-8 Citation: Therapeutics-on-a-chip (TOC): Manufacturing synthetic proteins for point-of-care therapeutics (2019, April 11) retrieved 18 August 2019 from https://phys.org/news/2019-04-therapeutics-on-a-chip-toc-synthetic-proteins-point-of-care.html LEFT: Overview and operation of the integrated cell-free protein synthesis and purification platform in 5 major steps: a) priming, b) protein synthesis, c) protein adsorption, washing, and elution, with an optional 6th step of bead refreshing. Credit: Microsystems & Nanoengineering, doi: 10.1038/s41378-019-0051-8. RIGHT: Cecropin B synthesis and purification using integrated CFPS + P microfluidic device. a) Tricine-PAGE of the cecropin B synthesized and purified by the integrated chip. M (marker); D (depleted): CFPS reaction mix after bead absorption; R (removed): removed contaminates in the purification buffer; P (product): purified AMP in the elution buffer. b) Optimization of cecropin B recovery using multiple adsorption cycles. c) Growth inhibition assays of E. coli conducted in triplicate, using the protein product (elution) after three adsorption/elution cycles by our device in comparison to cecropin B standards of different concentrations (0–100 ng/μl, denoted as STD 0-100). OD600 was measured every 30 min for 18 h. Elution with a concentration of 27 ng/μl in 60 μl solution was used. Trend lines that represent the average of three trials are added to guide the eye. Credit: Microsystems & Nanoengineering, doi: 10.1038/s41378-019-0051-8. © 2019 Science X Network The integrated system for cell-free protein synthesis and purification. a Micrograph of integrated CFPS + P platform. b Overview of integrated CFPS + P platform setup. The system consists of computer-controlled solenoid valves and syringe pumps connected to a microfluidic device placed on a heating stage. Credit: Microsystems & Nanoengineering, doi: 10.1038/s41378-019-0051-8. Overview of cell-free protein synthesis system. The synthesis system is made of three components: lysate, energy solution, and plasmid DNA. The lysate is collected from E. coli cells by cell lysis and prepared using ultracentrifugation. The energy solution is composed of nucleoside triphosphates (NTPs), amino acids, enzymes, and cofactors. The plasmid DNA is made by inserting the expressed gene of interest into an expression cassette. The three components are combined and incubated to synthesize protein of interest. Credit: Microsystems & Nanoengineering, doi: 10.1038/s41378-019-0051-8 In phase three, the scientists developed an integrated microfluidic platform with cell-free protein synthesis and purification (CFPS+P) for automation. They combined a continuous flow reactor and a batch purification device, although the two processes were not intrinsically compatible with each other to begin with. To accomplish adequate compatibility, they interfaced the two processes using a tube reservoir that stored the continuously produced protein on a chip, prior to purification. All apparatus used in the study to operate microfluidic system could potentially fit the size of a briefcase, making it a highly portable, therapeutic protein production system.In total, the fully integrated CFPS+P chip contained five major steps including, priming, protein synthesis, protein adsorption, washing and elution. In a sixth step, the scientists arranged bead refreshing. Murphy et al. used the serpentine synthesis channel as the individual synthesis module, after they synthesized the desired amount of protein, they shut down the setup from the purification module to initiate the subsequent process of purification. To test the workflow of the setup, the scientists used GFP and achieved a purity of 98 percent. In the second phase, Murphy et al. designed a microfluidic device for protein purification based on a high efficiency adsorption and washing protocol, as demonstrated by the same research team previously. They operated the device using solenoid valves to control the single micromechanical valve and associated oscillatory pressure pulses to perform protein purification in four major steps.In the work flow, steps were (1) bead loading, (2) protein adsorption, (3) washing and (4) elution. To optimize the process, the scientists compartmentalized the method to three different workflows. Murphy et al. then varied the conditions affecting the results of protein purification to achieve product purity as high as 98.5 percent, with a yield of 54.6 percent of the product, outperforming other methods. Explore furthercenter_img After CFPS+P workflow optimization using GFP, the scientists used the same setup to optimize the conditions to synthesize cecropin B. By following the steps of expression, purification, electrophoresis and staining in the setup, Murphy et al. confirmed the successful production and purification of cecropin B and recovered soluble proteins to elute 63 ng/µL, with a purity of 92 percent. They then tested the bioactivity of cecropin B relative to E. coli inhibition to demonstrate successful antibiotic activity by inhibiting bacterial growth. In this way, therapeutic proteins synthesized and purified using the microfluidic setup demonstrated active and effective suppression of bacterial growth. The cost-effective system can be actively integrated in low resource environments for frugal science. Murphy et al. intend to completely automate the system based on ongoing optimizations in the future. They envision applications of the setup to engineer a range of diverse therapeutic proteins for cost-effective point-of-care production. Journal information: Small , Nature Biomedical Engineering Simplified method makes cell-free protein synthesis more flexible and accessible Among the proteins examined in the study, cecropin B has a minimum inhibitory concentration of 9.5 ng/µL to exert antimicrobial effects. Using the microfluidic setup, the scientists combined protein synthesis and purification to produce an antimicrobial peptide cecropin B at a clinically relevant dose (63 ng/µL). The continuous-flow production in the setup was completed in three developmental phases: Cell-free protein synthesis (CFPS) reactor designPurification reactor (P) designIntegrated CFPS+P system designMurphy et al. used soft-lithography based polydimethylsiloxane (PMDS) molding to fabricate the devices; building multilayers using micromechanical valves. During the first stage of device design in the CFPS reactor, the scientists fabricated a serpentine channel microfluidic chip, similar to previous studies for on-chip protein synthesis. The microfluidic device contained inlets connected to a syringe pump placed on the heating stage of a microscope, where three inlets received (1) cell lysate, (2) CFPS reaction buffer and a (3) DNA template into the long serpentine channel (approximating 130 cm) with one outlet. The scientists fed the three reaction components at a combined flow rate of 0.15 µL/min driven by a syringe pump for a residence time of 1.5 hours. They heated the reactor with a stage heater (37 degrees C) and modeled the setup using COMSOL Multiphysics software to verify device mechanics, for optimal on-chip diffusion-based mixing and reaction. To validate the operating principles of the device, Murphy et al. synthesized the reporter protein, GFP using a variety of DNA templates. The system produced volumes of protein at a constant reaction time. , Cell Provided by Science X Network 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: Travis W. Murphy et al. On-chip manufacturing of synthetic proteins for point-of-care therapeutics, Microsystems & Nanoengineering (2019). DOI: 10.1038/s41378-019-0051-8 Andrea C. Timm et al. Toward Microfluidic Reactors for Cell-Free Protein Synthesis at the Point-of-Care, Small (2015). DOI: 10.1002/smll.201502764 Keith Pardee et al. Portable, On-Demand Biomolecular Manufacturing, Cell (2016). DOI: 10.1016/j.cell.2016.09.013 Sai Ma et al. Cell-type-specific brain methylomes profiled via ultralow-input microfluidics, Nature Biomedical Engineering (2018). DOI: 10.1038/s41551-018-0204-3 Therapeutic proteins are protein-based drug candidates bioengineered in the lab for pharmaceutical and clinical applications. Based on their pharmacokinetics, the candidates can be divided into groups that (1) replace a defective or abnormal protein, (2) augment an existing path in vivo, (3) provide a new function or activity in vivo, (4) interfere with activities of a molecule or organism and (5) deliver encapsulated proteins or compounds including, cytotoxic drugs, radionuclide or effector proteins.last_img read more

Read More →

Bone tissue engineering—nanoglue polymer membranes for robust bone regeneration

first_imgStep two: Surface characterization studiesSince bioactive membranes can integrate with surrounding osseous tissue (bone tissue), Deng et al. assessed the formation of bone apatite layers on the surface of biomaterials immersed in simulated body fluid (SBF) solution. After 7 days of immersion, the scientists observed clustered nodular aggregates on the PDA/PCL membranes, which increased dramatically by day 14. Comparatively, the control sample of pristine unmodified PCL retained Ca-P deposits at seven days, with islands of apatite by day 14. As the PDA content increased, therefore, the amount of apatite deposited on the surface increased. Deng et al. used the material characterization data to validate enhanced in vitro bioactivity of PDA/PCL membranes compared to the pure PCL control. Step three: Biofunctionalization studiesThe scientists assessed the cytocompatibility (cell biocompatibility) of the engineered PDA/PCL membranes relative to cell adhesion, spreading, and human mesenchymal stem cell (hMSCs) proliferation. The hMSCs largely exist in bone marrow to assist tissue repair during injury. After 6 hours of cell culture, the hMSCs with round cellular shapes did not adhere well on pure PCL but expressed filopodia for membrane surface attachment on three variants of PDA/PCL membranes. Using cell counting experiments and cell viability CCK-8 assays, Deng et al. showed that the content of PDA NPs significantly affected the number of viable cells attached on the surface, and observed optimal surface properties with the 2 percent PDA/PCL group in the work.The research team determined the optimal formula to engineer PDA/PCL membranes for guided bone tissue regeneration by determining the alkaline phosphatase (ALP) activity and calcium matrix production of hMSCs with Alizarin Red S (ARS) staining. Cell growth and osteogenic differentiation was low when the amounts of PDA NPs were either high or low, because low concentrations did not trigger cell growth, whereas high concentrations were toxic in the study. Since investigations at the molecular level are a powerful tool in biomaterials for bioengineering, Deng et al. investigated the interplay between hMSCs and engineered membranes using molecular tools. For this, they monitored the expression of osteogenesis-related genes ALP, Runx2, Col1a1 and OPN in hMSCs cultured on the membranes. At 7 days they observed substantial levels of ALP gene expression on the 2 percent PDA/PCL sample. By day 14, the level of Runx2 gene expressed on 1 and 2 percent PDA/PCL groups significantly outmatched the pure PCL group. However, by 21 days, the scientists did not observe a discernable difference among the four groups. They verified the observations using immunofluorescence staining and chose the 2 percent PDA/PCL membranes for optimal induction of hMSCs to differentiate into mature osteoblasts. Step four: Translational study Guided by the data from in vitro experiments, Deng et al. investigated the in vivo biofunctionality of the microfibrous membrane using an animal model. For this, they created critical-sized bone defects on mice skulls and placed fibrous membranes to cover the defects, followed by bone formation tests using micro-computed tomography (micro-CT), histological analyses and fluorescent labeling; four to eight weeks after implantation. When they examined the 3-D images of the micro-CT skulls, the 2 percent PDA/PCL membrane offered the largest areas of new bone formation, with considerable expansion to the center of the bone defect. The scientists obtained a higher content of calcified matrix and bone remodeling in the 2 percent PDA/PCL membranes for phenomenal osteoconductive integration. The team incubated the uncoated and coated membranes with stem cells isolated from bone marrow and implanted the membranes to regenerate skull bone defects in live mice. After a 2-month translational study, they revealed the ability of the sticky membranes to direct stem cells to produce significantly higher quantities of bone, compared with uncoated membranes. Bone defects and injuries can commonly occur at the microscopic level as congenital defects, due to accidents or as age-related degenerative disease. Most bone defects cannot be repaired spontaneously by self-healing mechanisms leading to an urgent requirement to develop robust biomaterials that facilitate bone repair in bone research and bone tissue engineering. Bioengineers can manipulate stem cell differentiation to form mature osteoblasts via guided tissue regeneration (GTR) on surface membranes for optimized, large-scale bone regeneration. In materials science and advanced functional materials, electrospun membranes have received massive attention for such guided tissue engineering strategies due to several biocompatible advantages, including:Biomimicry for stem cell attachmentLarge surface area to facilitate cell adhesion and growthThe ability to form 3-D fibrous membranes and accelerate the osteogenic potential of numerous stem cell lines (from mouse, rat and human species). Materials scientists classify synthetic GTR materials into two main categories as (1) bioabsorbable and (2) nonabsorbable materials; where nonabsorbable materials must be removed after implantation via a second surgery, causing increased healthcare expenses, while compromising newly generated tissue. In contrast, biodegradable membranes such as polyvinyl alcohol (PVA), poly (lactide-co-glycolide) (PLGA) or PCL are preferred for clinical implantations, although biological complications have seriously impeded their clinical adoption. In a new study now published on NPG Asia Materials, bioengineers report the development of a new fibrous membrane with stem cells to repair bone defects in the skulls of mice. For this, they incorporated mussel-inspired polydopamine protein as a promising compound to tether biological substances to the membrane surfaces, much like adhesive proteins in mussels. In the work, Yi Deng and a research team in the interdisciplinary departments of chemical engineering, mechanical engineering, materials technology, center for future materials and regenerative medicine in China and Australia, coated the biocompatible membranes with polydopamine nanoparticles to form many topological sites for calcium attachment and bone defect repair. More information: Yi Deng et al. Bioinspired and osteopromotive polydopamine nanoparticle-incorporated fibrous membranes for robust bone regeneration, NPG Asia Materials (2019). DOI: 10.1038/s41427-019-0139-5 Rabih O. Darouiche. Treatment of Infections Associated with Surgical Implants, New England Journal of Medicine (2004). DOI: 10.1056/NEJMra035415 Rajeswari Ravichandran et al. Precipitation of nanohydroxyapatite on PLLA/PBLG/Collagen nanofibrous structures for the differentiation of adipose derived stem cells to osteogenic lineage, Biomaterials (2011). DOI: 10.1016/j.biomaterials.2011.10.030 H. Lee et al. Mussel-Inspired Surface Chemistry for Multifunctional Coatings, Science (2007). DOI: 10.1126/science.1147241 TOP: Bone-like nodules formation. (a) SEM photographs of PDA/PCL fibrous membranes acquired after soaking in SBF for 7 and 14 days. (b) EDS data and Ca/P ratios of the particle sediments on the surface of PDA/PCL fibrous membranes at 14 days. BOTTOM: Cell attachment and proliferation. (a) SEM and b CLSM observation of adhering hMSCs on the engineered fibrous membranes with different PDA NP concentrations at 6 and 12 h. The red arrows in a point to the pseudopodia. The inserts in the upper right of (b) show the magnified images of a single cell. (c) Cell attachment and (d) proliferation curves of hMSCs on the sample surfaces obtained via CCK-8. * Represents p < 0.05 between groups, ** represents p < 0.01 between groups; and # represents p < 0.05 compared with other groups. Credit: NPG Asia Materials, doi: 10.1038/s41427-019-0139-5 TOP: Micro-morphologies of PDA NPs and electrospun PDA/PCL fibrous membranes. a TEM image of PDA NPs; b SEM images of the (b1) pristine PCL, (b2) 1% PDA/PCL, (b3) 2% PDA/PCL, (b4) 5% PDA/PCL, and (b5) 10% PDA/PCL fibrous membranes. The red arrows in b point to the filaments. BOTTOM: Chemical constituents of PDA/PCL fibrous membranes. (a) Raman spectra and (b) contact angles with corresponding water droplet images of PDA/PCL fibrous membranes. Credit: NPG Asia Materials, doi: 10.1038/s41427-019-0139-5 Journal information: New England Journal of Medicine New membrane class shown to regenerate tissue and bone, viable solution for periodontitis LEFT: In vivo evaluation of PDA/PCL fibrous membranes. (a) Reconstructed 3D micro-CT images of whole skulls after surgery at 8 weeks. (b) Quantification of new bone areas at 4 and 8 weeks. (c) Micro-CT images of the defects and d bone histomorphometry of membrane implants analyzed from the micro-CT data after 4 and 8 weeks. * represents p < 0.05 between groups, and & represents p < 0.05 compared with other groups. RIGHT: Histological and immunohistological analysis Histological and immunohistological analysis of the sections for calvarial defects only and defects implanted with PCL and 2% PDA/PCL fibrous membranes at 4 and 8 weeks post implantation: (a) H&E staining, (b) Masson staining, (c) toluidine blue staining, (d) and immunohistological staining of OCN. HB host bone; CT connective tissue; NB newly formed bone. The red arrows in a–c point to the blood vessel. Credit: NPG Asia Materials, doi: 10.1038/s41427-019-0139-5 The hematoxylin and eosin (H&E) staining revealed fibrous tissue in the cavities of the PCL group, with comparatively visible bone restructuring in the 2 percent PDA/PCL group. The scientists also observed bone with abundant vascularization after 8 weeks post-operation in the 2 percent PDA/PCL groups. They conducted further staining with Masson, toluidine blue and immunohistochemistry (IHC) staining to identify new bone and collagen formation in depth. The combined histological data revealed that employment of PDA NPs in engineered fibrous membranes significantly boost bone regeneration, supporting the hypothesis that in vitro osteodifferentiation was also effective in vivo. In this way, Yi Deng and co-workers bioengineered co-electrospun PDA NPs with a bioinert synthetic polymer to construct bioinspired, flexible and osteopromotive PDA/PCL fibrous membranes for bone tissue engineering applications in regenerative medicine. The amount of PDA NPs included in the composite significantly improved the chemical composition, fiber size and mechanical properties of the developed membranes. Both in vitro experiments and in vivo data validated the ability for new bone formation with 2 percent PDA/PCL constructs compared with pure PCL. The engineered PCL/PDA membranes are osteoconductive and easy to transplant with great potential for GTR applications. Explore further Osteogenic differentiation: a, b Coloration and quantification of ALP activity, c, d ARS staining and quantification of calcium production, and e RT-PCR analysis for osteo-specific genes on different PDA/PCL fibrous membranes. * represents p < 0.05 between groups, **represents p < 0.01 between groups. # represents p < 0.05 compared with other groups, and ## represents p < 0.05 compared with other groups. Credit: NPG Asia Materials, doi: 10.1038/s41427-019-0139-5 Citation: Bone tissue engineering—nano-glue polymer membranes for robust bone regeneration (2019, July 30) retrieved 18 August 2019 from https://phys.org/news/2019-07-bone-tissue-engineeringnano-glue-polymer-membranes.html , Biomaterials © 2019 Science X Network , Science In the present work, therefore, Deng et al. used the bioinspired adhesive protein secreted from mussels as a 'material-independent' and facile surface coating, engineering strategy based on catechol chemistry. Polydopamine (PDA) can facilitate osteoblastic differentiation of stem cells on a variety of substrates as a nanoscale biomaterials coating, to support mesenchymal stem cell attachment and induce reprogramming of human somatic cells. Nevertheless, PDA nanolayers can easily delaminate from surfaces to induce local cell apoptosis or inflammatory reactions as adverse effects. Deng et al. implemented specific experimental steps to overcome the existing limitations and develop a new biocompatible and biodegradable membrane in the lab. The newly engineered biomaterial or fibrous membrane will provide a favorable niche to steer the fates of local stem cells to form osteoblasts for bone regeneration. Step one: Engineering PDA-included PCL (PDA/PCL) with electrospinning The scientists used catechol chemistry for PDA/PCL fibrous membrane fabrication and synthesis. They uniformly dispersed the PDA nanoparticles (NPs) in PCL via continuous sonication and vortexing to form the fibrous membranes via electrospinning. Deng et al. used a scanning electron microscope (SEM) and observed surface properties of the random, micron-sized fibrous network. Comparatively, the pure PCL electrospun membranes remained smooth, whereas the integration of PDA NPs made the fiber surfaces rough. The scientists confirmed the new surface chemistry using Raman spectra and X-ray photoelectron spectroscopy (XPS) analysis. The biomaterials were hydrophilic allowing protein adsorption and cell attachment. The researchers conducted contact angle measurements to verify surface wettability and improved hydrophilicity after PDA modification compared to the pure, unmodified PCL membranes. Schematic drawing of the fabrication of the engineered membranes via electrospinning of PCL and PDA NPs. Credit: NPG Asia Materials, doi: 10.1038/s41427-019-0139-5 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

Read More →

Close Enough The Lure Of Living Through Others

first_img Now, as we sit on the couch and eat take-out, we watch kitchen virtuosos whip up gourmet meals from scratch. And then, we watch other people eat meals — there’s a popular genre on YouTube where you just watch other people binge eat. It has never been so easy to bring the world into our living rooms and kitchens and bedrooms. And the world that enters our lives has never looked better. Read the whole story: NPR These other lives we’ve come to inhabit can seem more beautiful, more exciting, more satisfying than anything in our actual lives. They come in multiple camera angles, with all the boring parts spliced out, and all the recipe ingredients pre-chopped in those little prep bowls. This week on Hidden Brain, we explore the delights — and the dangers — of living vicariousl It used to be that if you wanted to feel what it was like to do something, you had to go out and do it. If your dream was to see the Grand Canyon from a raft, you’d head to the river. If you wanted to gaze up close at the Mona Lisa, you’d go to Paris. But something in our culture has changed. last_img read more

Read More →

Arms smuggling case STF team heads out to Bihar

first_imgKolkata: A team of the Special Task Force (STF) of Kolkata Police has set out for Bihar to further probe in connection with the incident in which firearms from Rifle Factory Ishapore were smuggled to Maoists.The police decided to go to Bihar for investigation into the case, anticipating that the matter was not limited to smuggling of firearms to Maoists or anti-social groups in Bihar, but also to the rebel groups in the North East.The police have arrested six persons, including two from Bihar – Ajay Pandey alias Guddu Pandit and Jaysankar Pandey. Also Read – Heavy rain hits traffic, flightsThe police are considering Guddu to be one of the main persons behind the operation of the entire racket that had been operating from Bihar, with Jaysankar being one of his associates.Investigation has revealed that like Jaysankar, Guddu had many other close aides who used to look after the deals with the insurgent groups from North East. The police had also come to know that they used to get bullets from their counterparts in Punjab. The police are now trying to arrest the close aides of Guddu and at the same time, trying to find out who were helping them to get bullets from Punjab. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedIt may be mentioned that the police have reconstructed the plot on Tuesday. The police had taken Bhola, who was also arrested, to Rifle Factory Ishapore for reconstruction of the plot, following which they came to know about the involvement of some more officials of the rifle factory. The police have already arrested two officials of the rifle factory on Monday.The officials were summoned and they were also questioned in this connection, sources said, adding that the police have come to know about some more persons, who also hail from Bihar. Subsequently, a team comprising senior officers of STF was sent to Bihar and it has been learnt that they would be conducting raids at different places, including Patna and Nawada.During reconstruction of the plot on Tuesday, police have spotted the window from where they used to throw scrap firearms out of the room where it was stored. There was a huge quan-tity of firearms piled up in the storerooms. The police have also identified the places from where they used to scale the walls of the rifle factory, to avoid getting noticed while taking firearms out of the place.last_img read more

Read More →

Showcasing the best of Bali

first_imgBali resembles India in terms of culture as they have 95 per cent Hindu population but to know more about them, one has to visit the country and its exotic locations. For those who wish to know more about the culture, one can look at the photographs that will be showcased in an exhibition in the national Capital. The exhibition titled- ‘Women In Bali,’ which will begin on April 26, contains series of photographs that attempt to make a comparison of the role of women in India and Bali— two nations permeated by the same religious traditions. It also aims to reflect on the opportunity present for the women in society. Also Read – ‘Playing Jojo was emotionally exhausting’The narration of the exhibition flows through a kaleidoscope of women, immersed in their natural environment, in everyday life or portrayed in composite form. The images talk about an intertwining of existences that gradually expresses female role-play, a cultural pluralism, spiritual intensity and the importance of nature. Some of the images are imbued with a feeling of sacredness. The woman bowing her head in deep respect under a cascade of silver, the subject holding out her hand as crystal clear water gushes over it- which puts into focus the woman engaged in tending to an inundated rice field, juxtaposing not just the various roles of water but of the women as well. Also Read – Leslie doing new comedy special with NetflixElaborating more about her work, Bruna says, “The exhibition and the book seek to be homage to the island and all the women who live there. Over time, I have met many women, both from Bali and elsewhere, who have launched important artistic, ethical and social projects on the island. Through their portraits I have tried to grasp their essence, describing the force of the female energy symbolised by water, the holy water, a vehicle of ancient memories and an instrument of healing.” “Bali is a living island, a place that has always stirred in me contrasting emotions, stimulated by its fluid and changeable light, by a rituality made up of gestures that render the invisible visible and, above all, by a diffuse beauty that reflects a harmony that is continually reinvented”, adds Bruna Rotunno. The soundtrack for the exhibition has been composed by Eraldo Bernocchi, an Italian musician, producer and sound designer. The exhibition has been curated by Singapore based art consultant Sabiana Paoli in association with art historian Dr Alka Pande. Speaking about the artist’s work, Sabiana shares, “Bruna Rotunno’s affair with the island of Bali started 30 years ago, when she visited the islands for the first time. In a project spanning eight years, she has organised her gaze into a story in pictures where every gesture and every figure meticulously translates the essence of a unique place, characterised by a fluid and harmonious energy.”‘Women In Bali’ reflects the twin worlds of advertising and fashion through the pictures. The portraits of women pursue the mundane appear like finely finished stylish fashion pictures.last_img read more

Read More →

Creative Magnifier

first_imgUNICEF India and BBC Media Action India today launched a ‘coming of age’ action drama series for social change– AdhaFULL. The launch was graced by Dr A Surya Prakash, Chairman, Prasar Bharati, Louis-Georges Arsenault, UNICEF India Representative, Supriya Sahu, Director General Doordarshan, Priyanka Dutt, Country Director, BBC Media Action, officials from the Government of India, senior members from the media,civil society partners and adolescents themselves.  Also Read – Add new books to your shelfAdhaFULL, a 78 episode TV series, has been conceptualized and created by BBC Media Action, and developed in partnership with UNICEF. AdhaFULL follows three adolescents—Kitty (16), Tara (11) and Adrak (15), who form the AdhaFULL gang, as they solve a new case each week. The mysteries are intertwined with their journey of growing up in a small town. Issues such as under-age marriage, nutrition, stereotyping of girls and boys, continuing education, peer pressure, school drop-outs and exam blues and gender-based violence are creatively depicted in the narrative.  Also Read – Over 2 hours screen time daily will make your kids impulsiveSpeaking on the occasion, Louis-Georges Arsenault, UNICEF India Representative, said, “India is home to 243 million adolescents. This series portrays adolescents who stand up for their rights. Through a mix of social drama, action, energy, fun, humour and emotions, this edutainment package discusses existing social norms and showcases transformation from a culture of silence to a culture of change and freedom”The half-hour-long episodes of AdhaFULL, will be telecast on Doordarshan National on Friday, Saturday and Sunday every week between 7.30-8pm from October 21 onwards. “Doordarshan has the largest reach in India. We are happy to be the first channel to broadcast a dedicated programme for adolescents, engaging them so that they can reach their full potential”, said Dr A Surya Prakash, Chairman, Prasar Bharati. ‘AdhaFULL’, the Hinglish name of the series, reflects the hybrid nature of both a society in transition and adolescence. The ‘AdhaFULL’ gang episodes swing between its rural avtaar of the past and its present small town persona with urban trappings. “Young lives and aspirations are about the 3Cs – curiosity, challenge and creativity. Through AdhaFULL’s story and its characters, we want to engage our young viewers and their parents in a journey of change, so that they feel they can negotiate and work with the 3Cs”, says Radharani Mitra, Executive Producer, BBC Media Action.last_img read more

Read More →

Congress hails Priyankas appointment as general secretary for UP East

first_imgKolkata: The West Bengal unit of Congress on Wednesday welcomed Priyanka Gandhi Vadra’s appointment as general secretary for Uttar Pradesh East, and said it would boost the morale of the party ahead of the Lok Sabha polls. Ending years of speculation, Priyanka Gandhi formally entered politics in a move reflecting the party’s intent to go full throttle in the state ahead of the general elections. “We welcome Priyanka Gandhi Vadra’s appointment as Congress general secretary, as it would further boost the morale of the party ahead of Lok Sabha polls. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killed”This move will also further strengthen the organisation in the country, especially Uttar Pradesh,” senior Congress leader and MP Pradip Bhattacharya said. Several other top state Congress leaders, too, welcomed the move and congratulated Priyanka Gandhi. Carrying posters of Congress president Rahul Gandhi and Priyanka Gandhi, West Bengal Congress workers in different parts of the state celebrated her appointment by distributing sweets and bursting crackers.last_img read more

Read More →