Archive for July 2015

Journal : Tuning Organic Carbon Dioxide Absorbents for Carbonation and Decarbonation:
Dr's: Kim, Park & Rajamanickam
Funded by Ministry of Education. Science and Technology of the Korean Government

Carbon dioxide (CO₂ ) is a gas / waste product that is given off by motor engines and with it other harmful gases that affect us and affect pollution and air quality. In this new piece of research the trio of scientists have aimed to find a way to capture carbon and recycle it, from carbon dioxide and at the same time release the safe molecule oxygen (O₂).

In their research the scientists have aimed to manipulate the unique chemistry of super bases for carbon capture technology. It is beneficial to be able to control the process of carbonation and decarbonation in an easily controllable manner.

· Superbase = alkylcarbonyl salt

· Reverse at elevated temperatures in organic solutions

· Gives insight into the design and optimization of organic carbon dioxide absorbents

· Improved solvent systems can significantly reduce the energy cost of regeneration which is in great demand

The scientists found that the thermal stabilities of guanidinuim alkyl carbonates (the super base) are readily tuneable by altering the concentrations of super base/protic solvent/aprotic solvent mixtures. The protic and aprotic solvents act as stabilizers and destabilizers, respectively of the alkyl carbonate salt. The ternary mixtures are versatile CO₂ capture agents whose temperatures of carbonation and decarbonation are tuneable over a wide range.

Finally, the highly tuneable characteristics will allow the absorbents to be used for effective purification of CO₂ containing mixed-gases, not just to control carbon dioxide emissions, but also be able to produce value added gases by removing CO₂ impurities under anhydrous conditions. The solvent effects can have other uses in new switchable solvent /soft materials systems.

Infographic: Click to enlarge.

New Chemistry research: Black phosphorus could help engineers surmount one of the big challenges for future electronics: designing energy-efficient transistors.

This is a schematic of the "puckered honeycomb" crystal structure of black phosphorus.

Credit: Vahid Tayari/McGill University

Published in the journal: Nature Communications, the researchers are utilising black phosphorus as a material to pack more transistors on a chip, making them more energy-efficient.

The work is a result of a multidisciplinary collaboration among Szkopek's nanoelectronics research group, the nanoscience lab of McGill Physics Prof. Guillaume Gervais, and the nanostructures research group of Prof. Richard Martel in Université de Montréal's Department of Chemistry.

Reporting on their finds, the scientists at McGill University, have found that when electrons move in a phosphorus transistor, they do so only in two dimensions. This will help in designing new energy-efficient transistors.

"Transistors work more efficiently when they are thin, with electrons moving in only two dimensions," says Thomas Szkopek, an associate professor in McGill's Department of Electrical and Computer Engineering and senior author of the new study. "Nothing gets thinner than a single layer of atoms."

Eleven years ago, physicists at the University of Manchester in the U.K. first isolated and explored the remarkable properties of graphene (a one-atom-thick layer of carbon). After their great discovery, the scientists were keen to to investigate a range of other two-dimensional materials.

One of the new materials used is black phosphorus, a form of phosphorus that is similar to graphite and can be separated easily into single atomic layers, known as phosphorene.

Phosphorene is now a growing subject of interest because it overcomes many of the problems of using graphene in electronics. Where as graphene acts like a metal, black phosphorus is a natural semiconductor and it can be readily switched on and off.

"To lower the operating voltage of transistors, and thereby reduce the heat they generate, we have to get closer and closer to designing the transistor at the atomic level," Szkopek says. "The toolbox of the future for transistor designers will require a variety of atomic-layered materials: an ideal semiconductor, an ideal metal, and an ideal dielectric. All three components must be optimized for a well designed transistor. Black phosphorus fills the semiconducting-material role."

To understand the way the electrons in a phosphrorus transistor move, the researchers looked at the electrons under the under the influence of a magnetic field in experiments performed at the National High Magnetic Field Laboratory in Tallahassee, FL, which is the largest and highest-powered magnet laboratory in the entire world.

This research "provides important insights into the fundamental physics that dictate the behavior of black phosphorus," says Tim Murphy, DC Field Facility Director at the Florida facility.

"What's surprising in these results is that the electrons are able to be pulled into a sheet of charge which is two-dimensional, even though they occupy a volume that is several atomic layers in thickness," Szkopek says. That finding is significant because it could potentially facilitate manufacturing the material -- though at this point "no one knows how to manufacture this material on a large scale."

"There is a great emerging interest around the world in black phosphorus," Szkopek says. "We are still a long way from seeing atomic layer transistors in a commercial product, but we have now moved one step closer."

Research: http://www.nature.com/ncomms/2015/150707/ncomms8702/full/ncomms8702.html

Quotes and image from: http://www.sciencedaily.com/releases/2015/07/150707082346.htm

Infographic: Click to enlarge.

Everybody loves chocolate, who doesn't? Unless you are allergic to it. Almost every month, new research conducted on chocolate is published proving that chocolate is good for you and can even keep the doctor away.

Even though chocolate already contains beneficial compounds for our health, scientists have been working on integrating other chemicals in chocolate which can reduce the levels of potentially harmful chemicals in our body, such as cholesterol.

Infographic: Click to enlarge.

In a study conducted in the University of Sao Paulo in Brazil, researchers have produced phytosterol-enriched dark chocolate, as a potential functional food, which can lower cholesterol. Before this can even reach the public, the enriched chocolate has to go through several trials. In one of the researchers’ trials, they aimed to test the oxidative stability of the dark chocolate bar containing phytosterols. The oxidative stability of the samples was evaluated during 5 months at 20°C and 30°C.

First of all what are phytosterols?

Phytosterols are compounds that are similar to cholesterol, which occur in plants and vary only in carbon side chains and/or presence or absence of a double bond. They are found in seeds, vegetable oils and cereals. Phytosterols have the ability to reduce cholesterol levels in the body. Phytosterols reduce cholesterol levels by competing with cholesterol absorption in the gut via one or several possible mechanisms.

Because of their cholesterol reducing properties, some manufacturers are using sterols or stanols as a food additive. Phytosterol-enriched foods and dietary supplements have been sold for decades.

How did they make the chocolate bars?

The “control” Belgian Praline chocolates (30 g – 15g shell and 15g filling) were formulated by mixing cocoa powder, cocoa liquor, palm oil, polydextrose, rice protein, cocoa butter, xylitol, maltitol, hazelnut paste, erythritol, soy lecithin, polyglycerol polyricinoleate, nut flavor, sucralose and nut flavour.

Two different formulations were produced to test the oxidative stability of phytosterols: PHYT and PHAN. Since palm oil is usually used to prepare the filling, they replaced palm oil with two different plant sterols. In the PHAN group of chocolates, ascorbic acid and α-tocopherol were also added into the filling formulation (0.90 mg/100 g of chocolate).

So what did they find?

Based on the results from the study, the researchers found that the plant-sterol-enriched chocolate bars attained all relevant aspects for a satisfactory functional food development and can even be stored for up to 150 days without significant modifications in their nutritional and sensory profile. The daily intake of 1 bar (30 g) provided about 2.2 g of PS esters, which is higher than the amount required by the FDA (1.3 g).

Supplements in food not pills...

The chocolate bar developed in this study did not contain sugar and it was formulated with 50 g/100 g of cocoa, therefore it could potentially be useful for individuals with dyslipidemia, type 2 diabetes or metabolic syndrome.

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