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Category: chemistry – Page 177

I posted about Japan releasing radioactive water, and thought it was a bad idea, because of this MIT revelation.

Nuclear power continues to expand globally, propelled, in part, by the fact that it produces few greenhouse gas emissions while providing steady power output. But along with that expansion comes an increased need for dealing with the large volumes of water used for cooling these plants, which becomes contaminated with radioactive isotopes that require special long-term disposal.

Now, a method developed at MIT provides a way of substantially reducing the volume of contaminated water that needs to be disposed of, instead concentrating the contaminants and allowing the rest of the water to be recycled through the plant’s cooling system. The proposed system is described in the journal Environmental Science and Technology, in a paper by graduate student Mohammad Alkhadra, professor of chemical engineering Martin Bazant, and three others.

The method makes use of a process called shock electrodialysis, which uses an electric field to generate a deionization shockwave in the water. The shockwave pushes the electrically charged particles, or ions, to one side of a tube filled with charged porous material, so that concentrated stream of contaminants can be separated out from the rest of the water. The group discovered that two radionuclide contaminants — isotopes of cobalt and cesium — can be selectively removed from water that also contains boric acid and lithium. After the water stream is cleansed of its cobalt and cesium contaminants, it can be reused in the reactor.

Continue reading “A new way to remove contaminants from nuclear wastewater” | >

Scientists from UNSW Sydney have demonstrated a novel technique for creating tiny 3D materials that could eventually make fuel cells like hydrogen batteries cheaper and more sustainable.

In the study published in Science Advances (“Synthesis of hierarchical metal nanostructures with high electrocatalytic surface areas”), researchers from the School of Chemistry at UNSW Science show it’s possible to sequentially ‘grow’ interconnected hierarchical structures in 3D at the nanoscale which have unique chemical and physical properties to support energy conversion reactions.

In chemistry, hierarchical structures are configurations of units like molecules within an organisation of other units that themselves may be ordered. Similar phenomena can be seen in the natural world, like in flower petals and tree branches. But where these structures have extraordinary potential is at a level beyond the visibility of the human eye – at the nanoscale.

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Novel drugs, such as vaccines against COVID-19, among others, are based on drug transport using nanoparticles. Whether this drug transport is negatively influenced by an accumulation of blood proteins on the nanoparticle’s surface was not clarified for a long time.

Scientists at the Max Planck Institute for Polymer Research have now followed the path of such a particle into a cell using a combination of several microscopy methods. They were able to observe a cell-internal process that effectively separates blood components and .

Nanoparticles are a current field of research and it is impossible to imagine without them. They serve as microscopic drug capsules that are less than a thousandth of a millimeter in diameter. Among other things, they are used in current vaccines against COVID-19 to effectively deliver active ingredients to where they are actually needed. In most cases, the capsules dock onto cells, are enveloped by them, and are absorbed into them. Inside the cell, can then open the capsules, releasing the active ingredient.

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Quantum-enhanced single-parameter estimation is an established capability, with non-classical probe states achieving precisions beyond what can be reached by the equivalent classical resources in photonic1,2,3, trapped-ion4,5, superconducting6 and atomic7,8 systems. This has paved the way for quantum enhancements in practical sensing applications, from gravitational wave detection9 to biological imaging10. For single-parameter estimation, entangled probe states are sufficient to reach the ultimate allowed precisions. However, for multi-parameter estimation, owing to the possible incompatibility of different observables, entangling resources are also required at the measurement stage. The ultimate attainable limits in quantum multi-parameter estimation are set by the Holevo Cramér–Rao bound (Holevo bound)11,12. In most practical scenarios, it is not feasible to reach the Holevo bound as this requires a collective measurement on infinitely many copies of the quantum state13,14,15,16 (see Methods for a rigorous definition of collective measurements). Nevertheless, it is important to develop techniques that will enable the Holevo bound to be approached, given that multi-parameter estimation is fundamentally connected to the uncertainty principle17 and has many physically motivated applications, including simultaneously estimating phase and phase diffusion18,19, quantum super-resolution20,21, estimating the components of a three-dimensional field22,23 and tracking chemical processes24. Furthermore, as we demonstrate, collective measurements offer an avenue to quantum-enhanced sensing even in the presence of large amounts of decoherence, unlike the use of entangled probe states25,26.

To date, collective measurements for quantum multi-parameter metrology have been demonstrated exclusively on optical systems27,28,29,30,31,32. Contemporary approaches to collective measurements on optical systems are limited in their scalability: that is, it is difficult to generalize present approaches to measuring many copies of a quantum state simultaneously. The limited gate set available can also make it harder to implement an arbitrary optimal measurement. Indeed, the collective measurements demonstrated so far have all been restricted to measuring two copies of the quantum state and, while quantum enhancement has been observed, have all failed to reach the ultimate theoretical limits on separable measurements33,34. Thus, there is a pressing need for a more versatile and scalable approach to implementing collective measurements.

In this work, we design and implement theoretically optimal collective measurement circuits on superconducting and trapped-ion platforms. The ease with which these devices can be reprogrammed, the universal gate set available and the number of modes across which entanglement can be generated, ensure that they avoid many of the issues that current optical systems suffer from. Using recently developed error mitigation techniques35 we estimate qubit rotations about the axes of the Bloch sphere with a greater precision than what is allowed by separable measurements on individual qubits. This approach allows us to investigate several interesting physical phenomena: we demonstrate both optimal single-and two-copy collective measurements reaching the theoretical limits33,34. We also implement a three-copy collective measurement as a first step towards surpassing two-copy measurements. However, due to the circuit complexity, this measurement performs worse than single-copy measurements. We investigate the connection between collective measurements and the uncertainty principle. Using two-copy collective measurements, we experimentally violate a metrological bound based on known, but restrictive uncertainty relations36. Finally, we compare the metrological performance of quantum processors from different platforms, providing an indication of how future quantum metrology networks may look.

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The ultraviolet nail polish drying devices used to cure gel manicures may pose more of a public health concern than previously thought. Researchers at the University of California San Diego studied these ultraviolet (UV) light emitting devices, and found that their use leads to cell death and cancer-causing mutations in human cells.

The devices are a common fixture in nail salons, and generally use a particular spectrum of UV light (340-395nm) to cure the chemicals used in gel manicures. While tanning beds use a different spectrum of UV light (280-400nm) that studies have conclusively proven to be carcinogenic, the spectrum used in the nail dryers has not been well studied.

“If you look at the way these devices are presented, they are marketed as safe, with nothing to be concerned about,” said Ludmil Alexandrov, a professor of bioengineering as well as cellular and molecular medicine at UC San Diego, and corresponding author of the study published Jan. 17 in Nature Communications. “But to the best of our knowledge, no one has actually studied these devices and how they affect human cells at the molecular and cellular levels until now.”

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Lasers are intense beams of colored light. Depending on their color and other properties, they can scan your groceries, cut through metal, eradicate tumors, and even trigger nuclear fusion. But not every laser color is available with the right properties for a specific job.

To fix that, scientists have found a variety of ways to convert one color of laser light into another. In a study just published in the journal Physical Review Applied, scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory demonstrate a new color-shifting strategy that is simple, efficient, and highly customizable.

The new method relies on interactions between the laser and in the chemical bonds of materials called “.” These liquids are made only of positively and negatively charged ions, like ordinary table salt, but they flow like viscous fluids at room temperature. Simply shining a laser through a tube filled with a particular ionic liquid can downshift the laser’s energy and change its color while retaining other important properties of the laser beam.

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University of California, Berkeley, chemists have created a new type of material from millions of identical, interlocking molecules, that for the first time allows the synthesis of extensive 2D or 3D structures that are flexible, strong and resilient, like the chain mail that protected medieval knights.

The material, called an infinite catenane, can be synthesized in a single chemical step.

French chemist Jean-Pierre Sauvage shared the 2016 Nobel Prize in Chemistry for synthesizing the first catenane—two linked rings. These structures served as the foundation for making molecular structures capable of moving, which are often referred to as molecular machines.

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In a recent article published in Nature Materials, researchers reported a conductance-based organic electrochemical neuron (c-OECN) that mimicked biological signaling in neurons, especially activation/inactivation of their sodium and potassium channels.

Compilation of the top interviews, articles, and news in the last year.

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Scientists at University of Galway delved into the issue of antimicrobial resistance—one of the greatest threats to human health—discovering the potential to improve treatment options for superbug MRSA infections using penicillin-type antibiotics that have become ineffective on their own.

The research has been published in the journal mBio.

Professor James P O’Gara and Dr. Merve S Zeden in the School of Biological and Chemical Sciences, University of Galway, led the study.

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Atomic force microscopy (AFM) is a popular technique for interrogating surfaces on the micro and nano scales. The most common use for AFM is imaging; however, there are a variety of more specialized AFM techniques that can be used to determine electrical, mechanical, and chemical properties of surfaces. To adequately control the application of forces to surfaces for these techniques (especially mechanical property measurements), accurate stiffness calibrations of test cantilevers should be used.

There are a variety of test cantilever calibration techniques available, based on dimensional, static force and displacement, and dynamic vibrational methods, but in general, these have large uncertainties in the range of ± 10% to ± 30% and unknown accuracy. More rigorous calibrated balance techniques, with SI traceability have been pioneered, mostly by National Metrology Institutes (NMIs), but their complexity, expense, and time-consuming operation make them an out-of-reach technique for most AFM researchers. The reference cantilevers represented by NIST SRM 3,461 are an accurate and precise force calibration artifact for use in the field.

SRM 3,461 is a silicon microfabricated device containing seven cantilevers of carrying length and stiffness is used for validating methods for determining the stiffness of atomic microscope (AFM) cantilevers as well as directly calibrating AFM test cantilevers using the reference cantilever method.

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