Archive for the ‘chemistry’ category: Page 146

Nov 12, 2020

Luminescent and Hydrophobic Wood Films as Optical Lighting Materials

Posted by in categories: chemistry, particle physics, quantum physics

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.

Nov 12, 2020

Episode 24 — How Oxygen Transformed Our Planet Earth

Posted by in category: chemistry

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.

Continue reading “Episode 24 --- How Oxygen Transformed Our Planet Earth” »

Nov 11, 2020

Physicists produce world’s first neutron-rich, radioactive tantalum ions

Posted by in categories: chemistry, particle physics

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.

Nov 11, 2020

Scientists create a chemical space mapping method and crack the mystery of Mendeleev number

Posted by in categories: chemistry, information science, mapping, particle physics

Scientists have long sought a system for predicting the properties of materials based on their chemical composition. In particular, they set sights on the concept of a chemical space that places materials in a reference frame such that neighboring chemical elements and compounds plotted along its axes have similar properties. This idea was first proposed in 1984 by the British physicist, David G. Pettifor, who assigned a Mendeleev number (MN) to each element. Yet the meaning and origin of MNs were unclear. Scientists from the Skolkovo Institute of Science and Technology (Skoltech) puzzled out the physical meaning of the mysterious MNs and suggested calculating them based on the fundamental properties of atoms. They showed that both MNs and the chemical space built around them were more effective than empirical solutions proposed until then. Their research supported by a grant from the Russian Science Foundation’s (RSF) World-class Lab Research Presidential Program was presented in The Journal of Physical Chemistry C.

Systematizing the enormous variety of chemical , both known and hypothetical, and pinpointing those with a particularly interesting property is a tall order. Measuring the properties of all imaginable compounds in experiments or calculating them theoretically is downright impossible, which suggests that the search should be narrowed down to a smaller space.

David G. Pettifor put forward the idea of chemical space in the attempt to somehow organize the knowledge about material properties. The chemical space is basically a where elements are plotted along the axes in a certain sequence such that the neighboring elements, for instance, Na and K, have similar properties. The points within the space represent compounds, so that the neighbors, for example, NaCl and KCl, have similar properties, too. In this setting, one area is occupied by superhard materials and another by ultrasoft ones. Having the space at hand, one could create an algorithm for finding the best material among all possible compounds of all elements. To build their “smart” map, Skoltech scientists, Artem R. Oganov and Zahed Allahyari, came up with their own universal approach that boasts the highest predictive power as compared to the best-known methods.

Nov 11, 2020

Indianapolis Testing Advances Capabilities of Chemical, Biological Threat Detection Sensors

Posted by in categories: biological, chemistry, information science, transportation

DARPA’s SIGMA+ program conducted a week-long deployment of advanced chemical and biological sensing systems in the Indianapolis metro region in August, collecting more than 250 hours of daily life background atmospheric data across five neighborhoods that helped train algorithms to more accurately detect chemical and biological threats. The testing marked the first time in the program the advanced laboratory grade instruments for chemical and biological sensing were successfully deployed as mobile sensors, increasing their versatility on the SIGMA+ network.

“Spending a week gathering real-world background data from a major Midwestern metropolitan region was extremely valuable as we further develop our SIGMA+ sensors and networks to provide city and regional-scale coverage for chem and bio threat detection,” said Mark Wrobel, program manager in DARPA’s Defense Sciences Office. “Collecting chemical and biological environment data provided an enhanced understanding of the urban environment and is helping us make refinements of the threat-detection algorithms to minimize false positives and false negatives.”

SIGMA+ expands on the original SIGMA program’s advanced capability to detect illicit radioactive and nuclear materials by developing new sensors and networks that would alert authorities with high sensitivity to chemical, biological, and explosives threats as well. SIGMA, which began in 2014, has demonstrated city-scale capability for detecting radiological threats and is now operationally deployed with the Port Authority of New York and New Jersey, helping protect the greater New York City region.

Nov 11, 2020

A new and efficient way to create nanographene for power and display devices

Posted by in categories: chemistry, particle physics, solar power, sustainability

Nanographene is a material that could radically improve solar cells, fuel cells, LEDs and more. Typically, the synthesis of this material has been imprecise and difficult to control. For the first time, researchers have discovered a simple way to gain precise control over the fabrication of nanographene. In doing so, they have shed light on the previously unclear chemical processes involved in nanographene production.

Graphene, one-atom-thick sheets of carbon molecules, could revolutionize future technology. Units of graphene are known as ; these are tailored to specific functions, and as such, their fabrication process is more complicated than that of generic graphene. Nanographene is made by selectively removing from organic molecules of carbon and hydrogen, a process called dehydrogenation.

“Dehydrogenation takes place on a such as that of silver, gold or copper, which acts as a catalyst, a material that enables or speeds up a reaction,” said Assistant Professor Akitoshi Shiotari from the Department of Advanced Materials Science. “However, this surface is large relative to the target organic molecules. This contributes to the difficulty in crafting specific nanographene formations. We needed a better understanding of the catalytic process and a more precise way to control it.”

Nov 11, 2020

The Thermal Nuclear Engine That Could Get Us to Mars in Just 3 Months

Posted by in categories: chemistry, space travel

It’s twice as efficient as a chemical rocket.

Ultra Safe Nuclear Corporation (USNC) has designed a new thermal nuclear engine it says could carry astronauts to Mars in just three months—and back to Earth in the same amount of time. By using ceramic microcapsules of high assay low enriched uranium (HALEU) fuel, USNC’s thermal nuclear engine could cut the trip in half even from optimistic estimates.

🌌You like our badass universe. So do we. Let’s explore it together.

Nov 10, 2020

Machine learning advances materials for separations, adsorption and catalysis

Posted by in categories: chemistry, robotics/AI

An artificial intelligence technique—machine learning—is helping accelerate the development of highly tunable materials known as metal-organic frameworks (MOFs) that have important applications in chemical separations, adsorption, catalysis, and sensing.

Utilizing data about the properties of more than 200 existing MOFs, the machine learning platform was trained to help guide the development of new materials by predicting an often-essential property: water stability. Using guidance from the , researchers can avoid the time-consuming task of synthesizing and then experimentally testing new candidate MOFs for their aqueous stability. Already, researchers are expanding the model to predict other important MOF properties.

Supported by the Office of Science’s Basic Energy Sciences program within the U.S. Department of Energy (DOE), the research was reported Nov. 9 in the journal Nature Machine Intelligence. The research was conducted in the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), a DOE Energy Frontier Research Center located at the Georgia Institute of Technology.

Nov 10, 2020

Two genes regulate social dominance

Posted by in categories: biotech/medical, chemistry

Rank in social hierarchy is a condition not solely claimed by humans. In the animal kingdom, male peacocks exhibit brightly colored plumes to illustrate dominance, and underwater, male fish show pops of bright colors to do the same. Despite the links identified between social status, physiology and behavior, the molecular basis of social status has not been known, until now.

“We discovered that two paralogous androgen receptor genes control social status in African cichlid fish,” reports Beau Alward in the Proceedings of the National Academy of Sciences. Alward is an assistant professor of psychology at the University of Houston with a joint appointment in biology and biochemistry. Paralogs are duplicate genes; androgens are hormones like testosterone necessary for male sexual development.

“Testosterone binds to to exert its effects. What we found through genome editing is that the two genes encoding these receptors are required for different aspects of social status,” said Alward. “This type of coordination of social status may be fundamental across species that rely on social information to optimally guide physiology and behavior.”

Nov 10, 2020

Marine Fungi: A Source of Potential Anticancer Compounds

Posted by in categories: biotech/medical, chemistry

Metabolites from marine fungi have hogged the limelight in drug discovery because of their promise as therapeutic agents. A number of metabolites related to marine fungi have been discovered from various sources which are known to possess a range of activities as antibacterial, antiviral and anticancer agents. Although, over a thousand marine fungi based metabolites have already been reported, none of them have reached the market yet which could partly be related to non-comprehensive screening approaches and lack of sustained lead optimization. The origin of these marine fungal metabolites is varied as their habitats have been reported from various sources such as sponge, algae, mangrove derived fungi, and fungi from bottom sediments. The importance of these natural compounds is based on their cytotoxicity and related activities that emanate from the diversity in their chemical structures and functional groups present on them. This review covers the majority of anticancer compounds isolated from marine fungi during 2012–2016 against specific cancer cell lines.

Marine fungi are important source of secondary metabolites useful for the drug discovery purposes. Even though marine fungi are less explored in comparison to their terrestrial counterparts, a number of useful hits have been obtained from the drug discovery perspective adding to their importance in the natural product discovery (Molinski et al., 2009; Butler et al., 2014), which have yielded a wide range of chemically diverse agents with antibacterial, antiviral and anticancer properties in animal systems. Starting with the celebrated example of cephalosporins, marine fungi have provided unique chemical skeletons that could be used to develop drugs of clinical importance (Bhadury et al., 2006; Saleem et al., 2007; Javed et al., 2011; Sithranga and Kathiresan, 2011). Fungi, in general, have been generous source of drugs as evidenced by the isolation of many drugs in use such as paclitaxel, camptothecin, vincristine, torreyanic acid and cytarabine to name a few.