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Category: chemistry – Page 312

First introduced into wide use in the middle of the 20th century, nuclear magnetic resonance (NMR) has since become an indispensable technique for examining materials down to their atoms, revealing molecular structure and other details without interfering with the material itself.

“It’s a broadly used technique in , materials characterization, MRI—situations in which you do a non-invasive analysis, but with atomic and molecular details,” said UC Santa Barbara chemistry professor Songi Han. By placing a sample in a strong magnetic field and then probing it with radio waves scientists can determine from the response from the oscillating nuclei in the material’s atoms the of the material.

“However, the problem with NMR has been that because it’s such a low-energy technique, it’s not very sensitive,” Han said. “It’s very detailed, but you don’t get much signal.” As a result, large amounts of sample material may be needed relative to other techniques, and the signals’ general weakness makes NMR less than ideal for studying complex chemical processes.

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China faces an additional geopolitical challenge in chip fabrication and assembly. Just a handful of Japanese companies dominate the global market in silicon wafers, photoresists, and essential packaging chemicals. These companies are well-regarded for their high-quality production capabilities and their products are not easily replaceable even by a manufacturing heavyweight such as China. In a changing world where strategic concerns are guiding technology flows, China’s chip ambitions can be foiled not just by the US but also by Japan and Taiwan.

China’s state-backed funds may well spur private investment, even producing a few champions, but are unlikely to result in a self-sufficient Chinese chip industry any time soon.

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O,.o.

Physicists from MIPT and Vladimir State University, Russia, have converted light energy into surface waves on graphene with nearly 90% efficiency. They relied on a laser-like energy conversion scheme and collective resonances. The paper was published in Laser & Photonics Reviews.

Manipulating light at the nanoscale is a task crucial for being able to create ultracompact devices for optical conversion and storage. To localize light on such a small scale, researchers convert optical radiation into so-called plasmon-polaritons. These SPPs are oscillations propagating along the interface between two materials with drastically different refractive indices—specifically, a metal and a dielectric or air. Depending on the materials chosen, the degree of surface wave localization varies. It is the strongest for light localized on a material only one atomic layer thick, because such 2-D materials have high refractive indices.

The existing schemes for converting light to SPPs on 2-D surfaces have an efficiency of no more than 10%. It is possible to improve that figure by using intermediary signal converters—nano-objects of various chemical compositions and geometries.

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Magnets are to be found everywhere in our daily lives, whether in satellites, telephones or on fridge doors. However, they are made up of heavy inorganic materials whose component elements are, in some cases, of limited availability.

Now, researchers from the CNRS, the University of Bordeaux and the ESRF (European Synchrotron Radiation Facility in Grenoble)[1] have developed a new lightweight molecule-based magnet, produced at low temperatures, and exhibiting unprecedented magnetic properties.

This compound, derived from coordination chemistry[2], contains chromium, an abundant metal, and inexpensive organic molecules. This is the first molecule-based magnet that exhibits a ‘memory effect’ (i.e. it is capable of maintaining one of its two magnetic states) up to a temperature of 240 °C. This effect is measured by what is known as a coercive field, which is 25 times higher at room temperature for this novel material than for the most efficient of its molecule-based predecessors. This property therefore compares well with that of certain purely inorganic commercial magnets.

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Cambridge/Jena (16.11.2020) Linkages between organic and inorganic materials are a common phenomenon in nature, e.g., in the construction of bones and skeletal structures. They often enable combinations of properties that could not be achieved with just one type of material. In technological material development, however, these so-called hybrid materials still represent a major challenge today.

A new class of hybrid glass materials

Researchers from the Universities of Jena (Germany) and Cambridge (GB) have now succeeded in creating a new class of hybrid glass materials that combine organic and inorganic components. To do this, the scientists use special material combinations in which chemical bonds between organometallic and inorganic glasses can be generated. They included materials composed of organometallic networks—so-called metal-organic frameworks (MOFs)—which have recently been experiencing rapidly increasing research interest. This is primarily because their framework structures can be created in a targeted manner, from the length scale of individual molecules up to a few nanometers. This achieves a control of porosity which can be adapted to a large number of applications, both in terms of the size of the pores and their permeability, and in terms of the chemical properties prevailing on the pore surfaces.

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Interesting.

The building blocks of life can form even before there are stars or planets, a team of researchers have found in a study.

The new research looked at “dark chemistry”, or the ways that new kinds of materials can form without energetic radiation.

They were able to simulate the conditions that govern chemistry in space, before the stars and planets that today surround us are formed, and there are instead dense interstellar clouds that will eventually go on to form those more solid objects.

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Ira Pastor, ideaXme life sciences ambassador and CEO Bioquark interviews Dr. Michelle Francl the Frank B. Mallory Professor of Chemistry, at Bryn Mawr College, and an adjunct scholar of the Vatican Observatory.

Ira Pastor comments:

Today, we have another fascinating guest working at the intersection of cutting edge science and spirituality.

Dr. Michelle Francl is the Frank B. Mallory Professor of Chemistry, at Bryn Mawr College, a distinguished women’s college in the suburbs of Philadephia, as well as an adjunct scholar of the Vatican Observatory.

Dr. Francl has a Ph.D. in chemistry from University of California, Irvine, did her post-doctoral research at Princeton University, and has taught physical chemistry, general chemistry, and mathematical modeling at Bryn Mawr College since 1986. In addition Dr. Francl has research interests in theoretical and computational chemistry, structures of topologically intriguing molecules (molecules with weird shapes), history and sociology of science, and the rhetoric of science.

Dr. Francl is noted for developing new methodologies in computational chemistry, is on a list of the 1,000 most cited chemists, is a member of the editorial board for the Journal of Molecular Graphics and Modelling, is active in the American Chemical Society, and the author of “The Survival Guide for Physical Chemistry”. In 1994, she was awarded the Christian R. and Mary F. Lindback Award by Bryn Mawr College for excellence in teaching.

Continue reading “Tripping Over the Mysteries of the Universe: Molecules, Particles and People” | >

Most materials used for optical lighting applications need to produce a uniform illumination and require high mechanical and hydrophobic properties. However, they are rarely eco-friendly. Herein, a bio-based, polymer matrix-free, luminescent, and hydrophobic film with excellent mechanical properties for optical lighting purposes is demonstrated. A template is prepared by turning a wood veneer into porous scaffold from which most of the lignin and half of the hemicelluloses are removed. The infiltration of quantum dots (CdSe/ZnS) into the porous template prior to densification resulted in almost uniform luminescence (isotropic light scattering) and could be extended to various quantum dot particles, generating different light colors. In a subsequent step, the luminescent wood film is coated with hexadecyltrimethoxysilane (HDTMS) via chemical vapor deposition. The presence of the quantum dots coupled with the HDTMS coating renders the film hydrophobic (water contact angle ≈ 140°). This top-down process strongly eliminates lumen cavities and preserves the orientation of the original cellulose fibrils to create luminescent and polymer matrix-free films with high modulus and strength in the direction of fibers. The proposed optical lighting material could be attractive for interior designs (e.g., lamps and laminated cover panels), photonics, and laser devices.

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Earth’s earliest beginnings from magma oceans to continents with elephants and oceans with Orcas can arguably be traced to the rise of Oxygen. That’s the topic of this week’s episode. Please have a listen.

From Pachyderms to Cetaceans, the largest mammals on Earth would arguably never have evolved to their gargantuan sizes without the third most abundant element in the Cosmos — Oxygen. Of course, life, even photosynthesis is possible without Oxygen, but for the cosmos to evolve the big-headed space aliens of our sci-fi dreams will likely take Oxygen — the most efficient energy carrier in the periodic table. How Oxygen became dominant on our own planet is the focus of today’s episode with guest Timothy Lyons, a biogeochemist at the University of California, Riverside.

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An international team of scientists have unveiled the world’s first production of a purified beam of neutron-rich, radioactive tantalum ions. This development could now allow for lab-based experiments on exploding stars helping scientists to answer long-held questions such as “where does gold come from?”

In a paper published in Physical Review Letters, the University of Surrey together with its partners detail how they used a new isotope-separation facility, called KISS, which is developed and operated by the Wako Nuclear Science Centre (WNSC) in the High Energy Accelerator Research Organization (KEK), Japan, to make beams of heavy isotopes.

The chemical element of tantalum is extremely difficult to vaporize, so the team had to capture radioactive tantalum atoms in high-pressure argon gas, ionizing the atoms with precisely tuned lasers. A single isotope of radioactive tantalum could then be selected for detailed investigation.

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