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Category: chemistry – Page 330

There are several ways to generate power from that mixing. And a couple of blue energy power plants have been built. But their high cost has prevented widespread adoption. All blue energy approaches rely on the fact that salts are composed of ions, or chemicals that harbor a positive or negative charge. In solids, the positive and negative charges attract one another, binding the ions together. (Table salt, for example, is a compound made from positively charged sodium ions bound to negatively charged chloride ions.) In water, these ions detach and can move independently.

By pumping the positive ions—like sodium or potassium—to the other side of a semipermeable membrane, researchers can create two pools of water: one with a positive charge, and one with a negative charge. If they then dunk electrodes in the pools and connect them with a wire, electrons will flow from the negatively charged to the positively charged side, generating electricity.

In 2013, French researchers made just such a membrane. They used a ceramic film of silicon nitride—commonly used in industry for electronics, cutting tools, and other uses—pierced by a single pore lined with a boron nitride nanotube (BNNT), a material being investigated for use in high-strength composites, among other things. Because BNNTs are highly negatively charged, the French team suspected they would prevent negatively charged ions in water from passing through the membrane (because similar electric charges repel one another). Their hunch was right. They found that when a membrane with a single BNNT was placed between fresh- and saltwater, the positive ions zipped from the salty side to the fresh side, but the negatively charged ions were mostly blocked.

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The oxygen evolution reaction (OER) is a chemical process that leads to the generation of molecular oxygen. This reaction is of key importance for the development of clean energy technologies, including water electrolyzers, regenerative fuel cells and rechargeable metal-air batteries.

The extent to which this reaction occurs has so far been limited in many materials, which has restricted the conversion efficiency of some types of technologies. Materials scientists have thus been trying to identify alternative materials, including metals, and hydroxides, that could be used as electrocatalysts to fuel this reaction. The materials identified so far, however, are far from ideal for large-scale implementation, as they are either not particularly resistant or too expensive.

A class of materials widely investigated as possible electrocatalysts for the OER are (MOFs), hybrid and crystalline compounds that consist of a regular array of positively charged metal ions surrounded by organic molecules. While these materials have promising , scientists have yet to identify optimal strategies to enhance their performance.

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Researchers identify Brown-Zak fermions in superlattices made from the carbon sheet.

Researchers at the University of Manchester in the UK have identified a new family of quasiparticles in superlattices made from graphene sandwiched between two slabs of boron nitride. The work is important for fundamental studies of condensed-matter physics and could also lead to the development of improved transistors capable of operating at higher frequencies.

In recent years, physicists and materials scientists have been studying ways to use the weak (van der Waals) coupling between atomically thin layers of different crystals to create new materials in which electronic properties can be manipulated without chemical doping. The most famous example is graphene (a sheet of carbon just one atom thick) encapsulated between another 2D material, hexagonal boron nitride (hBN), which has a similar lattice constant. Since both materials also have similar hexagonal structures, regular moiré patterns (or “superlattices”) form when the two lattices are overlaid.

If the stacked layers of graphene-hBN are then twisted, and the angle between the two materials’ lattices decreases, the size of the superlattice increases. This causes electronic band gaps to develop through the formation of additional Bloch bands in the superlattice’s Brillouin zone (a mathematical construct that describes the fundamental ideas of electronic energy bands). In these Bloch bands, electrons move in a periodic electric potential that matches the lattice and do not interact with one another.

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The technology doesn’t seem to be here yet; obviously, the ice on Mars will be harvested to provide drinking and irrigation water.

If we ever intend to send crewed missions to deep-space locations, then we need to come up with solutions for keeping the crews supplied. For astronauts aboard the International Space Station (ISS), who regularly receive resupply missions from Earth, this is not an issue. But for missions traveling to destinations like Mars and beyond, self-sufficiency is the name of the game.

This is the idea behind projects like BIOWYSE and TIME SCALE, which are being developed by the Centre for Interdisciplinary Research in Space (CIRiS) in Norway. These two systems are all about providing astronauts with a sustainable and renewable supply of drinking water and plant food. In so doing, they address two of the most important needs of humans performing long-duration missions that will take them far from home.

Even though the ISS can be resupplied in as little as six hours (the time between launch and the time a supply capsule will dock with the station), astronauts still rely on conservation measures while in orbit. In fact, roughly 80% of the water aboard the ISS comes from airborne water vapor generated by breathing and sweat, as well as recycled shower water and urine—all of which is treated with chemicals to make it safe for drinking.

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Scientists have established a new method to image proteins that could lead to new discoveries in disease through biological tissue and cell analysis and the development of new biomaterials that can be used for the next generation of drug delivery systems and medical devices.

Scientists from the University of Nottingham in collaboration with the University of Birmingham and The National Physical laboratory have used the state-of-the-art 3D OrbiSIMS instrument to facilitate the first matrix- and label-free in situ assignment of intact proteins at surfaces with minimal sample preparation. Their research has been published today in Nature Communications.

The University of Nottingham is the first University in the world to own a 3D OrbiSIMS instrument. It is able to facilitate an unprecedented level of mass spectral molecular analysis for a range of materials (hard and soft matter, biological cells and tissues). The facility in Nottingham also has freezing cryo-preparation facilities that enable biological samples to be maintained close to their native state as frozen-hydrated to complement the more commonly applied but more disruptive freeze drying and sample fixation. When the surface sensitivity, high mass/spatial resolution are combined with a depth profiling sputtering beam, the instrument becomes an extremely powerful tool for 3D chemical analysis as demonstrated in this recent work.

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Neurodegenerative diseases (NDDs) include more than 600 types of nervous system disorders in humans that impact tens of millions of people worldwide. Estimates by the World Health Organization (WHO) suggest NDDs will increase by nearly 50% by 2030. Hence, development of advanced models for research on NDDs is needed to explore new therapeutic strategies and explore the pathogenesis of these disorders. Different approaches have been deployed in order to investigate nervous system disorders, including two-and three-dimensional (2D and 3D) cell cultures and animal models. However, these models have limitations, such as lacking cellular tension, fluid shear stress, and compression analysis; thus, studying the biochemical effects of therapeutic molecules on the biophysiological interactions of cells, tissues, and organs is problematic. The microfluidic “organ-on-a-chip” is an inexpensive and rapid analytical technology to create an effective tool for manipulation, monitoring, and assessment of cells, and investigating drug discovery, which enables the culture of various cells in a small amount of fluid (10−9 to 10−18 L). Thus, these chips have the ability to overcome the mentioned restrictions of 2D and 3D cell cultures, as well as animal models. Stem cells (SCs), particularly neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and embryonic stem cells (ESCs) have the capability to give rise to various neural system cells. Hence, microfluidic organ-on-a-chip and SCs can be used as potential research tools to study the treatment of central nervous system (CNS) and peripheral nervous system (PNS) disorders. Accordingly, in the present review, we discuss the latest progress in microfluidic brain-on-a-chip as a powerful and advanced technology that can be used in basic studies to investigate normal and abnormal functions of the nervous system.

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When light falls on a material, such as a green leaf or the retina, certain molecules transport energy and charge. This ultimately leads to the separation of charges and the generation of electricity. Molecular funnels, so-called conical intersections, ensure that this transport is highly efficient and directed.

An international team of physicists has now observed that such conical intersections also ensure a directed energy transport between neighboring of a nanomaterial. Theoretical simulations have confirmed the . Until now, scientists had observed this phenomenon only within one molecule. In the long term, the results could help to develop more efficient nanomaterials for organic solar cells, for example. The study, led by Antonietta De Sio, University of Oldenburg, and Thomas Frauenheim, University of Bremen, Germany, was published in the current issue of the scientific journal Nature Nanotechnology.

Photochemical processes play a major role in nature and in technology: When molecules absorb light, their electrons transit to an excited state. This transition triggers extremely fast molecular switching processes. In the human eye, for example, the molecule rhodopsin rotates in a certain way after absorbing light and thus ultimately triggers an electrical signal—the most elementary step in the visual process.

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Senescence in cancer cells

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Sometimes, too much of a good thing can turn out to be bad. This is certainly the case for the excessive cell growth found in cancer. But when cancers try to grow too fast, this excessive speed can cause a type of cellular aging that actually results in arrested growth. Scientists at Duke-NUS Medical School have now discovered that a well-known signaling pathway helps cancers grow by blocking the pro-growth signals from a second major cancer pathway.

Inhibiting Wnt signaling with ETC-159 reactivates the hyperactive RAS-MAPK , causing cells to led undergo senescence. Many cancers are driven by activating mutations in the RAS-MAPK signaling pathway which triggers a cascade of proteins that directs cells to grow, divide and migrate. Mutations in proteins involved in this cascade can turn on genes that make this process go into overdrive, causing cells to grow out of control and aggressively invade other parts of the body. However, too much RAS-MAPK signaling causes cancer cells to prematurely age, and eventually stop growing—a process called cellular senescence.

Publishing in Cancer Research, the Duke-NUS research team found that another important and well-known biochemical pathway, the Wnt (pronounced “wint”) signaling pathway, allows some cancers to grow by dampening RAS-MAPK signaling.

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