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Category: chemistry – Page 188

The cloud condensation nuclei activation of sea spray aerosol (SSA) is tightly linked to the hygroscopic properties of these particles and is defined by their physical and chemical properties. While hygroscopic sea salt in SSA strongly influences particle water uptake, the marine-derived components that make up the organic fraction of SSA constitute a complex mixture, and their effect on hygroscopic growth is unknown. To constrain the effect of organic compounds and specifically surface-active compounds that adsorb on particle interfaces, particle hygroscopic growth studies were performed on laboratory-generated model sea salt/sugar particles. For sea salt/glucose particles, ionic surfactants facilitated water uptake at low relative humidity (RH), increasing the particle growth factor (GF) by up to 7.61%, and caused a reduction in the deliquescence relative humidity (DRH), while nonionic surfactants had a minimal effect. Replacing glucose with polysaccharide laminarin in sea salt/sugar/surfactant particles caused a reduction in GF at low RHs and minimized the effect of ionic surfactants on the DRH. At RHs above the DRH, the addition of anionic or nonionic surfactants caused a decrease in GF for both sea salt/glucose and sea salt/laminarin particles. The addition of cationic surfactants, however, did not have a dampening effect on water uptake of sea salt/sugar particles and even showed a GF increase of up to 3.7% at 90% RH. An increase in the complexity of the sugar dampens the water uptake for particles containing nonionic surfactants but increases the water uptake for cationic surfactants. The cloud activation potential for 100 nm particles analyzed in this study is higher for ionic surfactants and decreases with an increase in surfactant molecular size when particle interfacial tension is considered. The surfactant effect on the hygroscopic growth and cloud activation potential of the particles containing sea salt/sugar is dependent on the surfactant ionicity and molecular size, the particle size and interfacial tension, and the interactions between inorganic salt and organic species under different RH conditions.

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It takes chemist Liaisan Khasanova less than a minute to turn an ordinary silica glass tube into a printing nozzle for a very special 3D printer. The chemist inserts the capillary tube—which is just one millimeter thick—into a blue device, closes the flap and presses a button. After a few seconds there is a loud bang and the nozzle is ready for use.

“A laser beam inside the device heats up the tube and pulls it apart. Then we suddenly increase the tensile force so that the glass breaks in the middle and a very sharp tip forms,” explains Khasanova, who is working on her Ph.D. in chemistry in the Electrochemical Nanotechnology Group at the University of Oldenburg, Germany.

Khasanova and her colleagues need the minuscule nozzles to print incredibly tiny three-dimensional metallic structures. This means the nozzles’ openings must be equally tiny—in some cases so small that only a single molecule can squeeze through. “We are trying to take 3D printing to its technological limits,” says Dr. Dmitry Momotenko, who leads the junior research group at the Institute of Chemistry. His goal: “We want to assemble objects atom by atom.”

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The team has successfully tested a sustainable membrane-based seawater electrolyzer.

A research team in China has developed a device to split salty seawater to produce hydrogen directly. The device, a membrane-based seawater electrolyzer, helps address the side-reaction and corrosion problems of traditional methods.

Why traditional methods are not sustainable.

Petmal/iStock.

Continue reading “Researchers in China create device to directly split seawater to produce hydrogen” | >

Leading Canada’s Bio-Safety & Security R&D — Dr. Loren Matheson PhD, Defence Research and Development Canada, Department of National Defence.

Dr. Loren Matheson, Ph.D. is a Portfolio Manager at the Center For Security Science, at Defence Research and Development Canada (DRDC — https://www.canada.ca/en/defence-research-development.html), which is a special operating agency of the Department of National Defence, whose purpose is to provide the Canadian Armed Forces, other government departments, and public safety and national security communities with knowledge and technology.

With a focus on the chemical and biological sciences at DRDC, Dr. Matheson develops and leads safety and security R&D projects with government partners, industry and academia. In addition, she spearheaded an effort to establish a virtual symposium series, developed communications products to explain their program to national and international partners, and helped established a science communication position.

Continue reading “Dr Loren Matheson, PhD — Centre for Security Science, DRDC — Leading Canada’s Safety & Security R&D” | >

Material scientists at RIKEN have created a self-healing polymer by using an off-the-shelf compound for the first time. The strategy they used is promising for improving the durability and minimizing the environmental impact of various commercial polymers for a wide range of applications.

Polymers capable of healing themselves when damaged would last longer and thus reduce costs and the burden on the environment. Current strategies for producing self-healing polymers mainly employ reversible , but this usually entails complex synthesis processes. Furthermore, self-healing mechanisms based on chemical reactions may not work in certain environments such as in water and acidic and alkaline solutions.

Ideally, would like to produce polymers that self-heal under a wide range of conditions, from readily available materials, using simple synthesis processes.

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Engineers at the University of Illinois Chicago have built a machine that captures carbon from flue gas and converts it to ethylene.

The device integrates a system with an ethylene conversation system for the first time. Moreover, the system not only runs on electricity, but it also removes more carbon from the environment than it generates—making it what scientists call net-negative on carbon emissions.

Among manufactured chemicals worldwide, ethylene ranks third for after ammonia and cement. Ethylene is used not only to create plastic products for the packaging, agricultural and automotive industries but also to produce chemicals used in antifreeze, medical sterilizers and vinyl siding for houses, for example.

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Though plants can serve as a source of food, oxygen and décor, they’re not often considered to be a good source of electricity. But by collecting electrons naturally transported within plant cells, scientists can generate electricity as part of a “green,” biological solar cell.

Now, researchers reporting in ACS Applied Materials & Interfaces have, for the first time, used a succulent plant to create a living “bio-solar cell” that runs on photosynthesis.

In all , from bacteria and fungi to and animals, electrons are shuttled around as part of natural, biochemical processes. But if electrodes are present, the cells can actually generate electricity that can be used externally. Previous researchers have created fuel cells in this way with bacteria, but the microbes had to be constantly fed. Instead, scientists, including Noam Adir’s team, have turned to photosynthesis to generate current.

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A study of neutrinos from the Sun has measured the signal from the so-called CNO cycle, offering a direct measure of the elemental abundances in the Sun’s core.

Solar neutrinos are copiously produced by hydrogen fusion reactions in the Sun’s core. Therefore, they are the direct evidence that the Sun is powered by nuclear reactions. Measurements of solar neutrinos have provided information about the temperature and density of the solar interior, but uncertainties remain about the chemical ingredients. Now the Borexino Collaboration reports a new measurement of the neutrino flux produced by the so-called CNO hydrogen burning cycle in the Sun [1]. This cycle—which requires the presence of carbon ©, nitrogen (N), and oxygen (O)—produces neutrinos that carry enormous diagnostic power relating to the properties of the solar interior. By measuring these neutrinos, the collaboration provides a precious piece of information about the elemental makeup of the Sun, bringing us closer to resolving a controversy that has plagued solar physics for over 20 years [2].

Stars spend about 90% of their lifetimes fusing hydrogen into helium, producing two neutrinos in the process. The pp chain—or proton–proton chain—and CNO cycle are the two fundamental modes by which stellar fusion occurs. Whether a star is dominated by the pp chain or the CNO cycle depends on its core temperature, which is primarily determined by the mass of the star. In the Sun and similar low-mass stars, the pp chain generates almost all the nuclear energy; the CNO cycle is the main power source for more massive stars. The pp chain is a series of nuclear reactions that require no additional nuclei besides hydrogen as fuel. By contrast, the CNO cycle relies on the presence of C, N, and O nuclei as catalysts in the production of helium (Fig. 1). In the Sun, this catalytic process introduces a linear dependence between the amount of C, N, and O and the flux of CNO neutrinos. Thus, CNO neutrinos are a powerful tool for probing the chemical composition in the Sun’s core.

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