What’s The Function Of Artificial Leaves?

Did you know that just one-thousandth of the sun’s light that reaches the earth could satisfy all of humanity’s energy nine times over? What if we capture this energy cheaply? Perhaps, artificial leaves are the answer?

Solar energy
Today we have solar cells to make energy. But there are some problems. If it gets cloudy, these cells aren’t much use. Solar cells are also expensive. Also, they do not convert light into electricity very efficiently.
But there is a solar cell that’s been around for two billion years that’s perfect. It is the leaf of a plant!

How natural leaves do it
As you know, leaves are the part of a plant where photosynthesis occurs. In this, the leaf uses light energy to convert carbon dioxide & water into glucose.

Photosynthesis has two parts. One part is where hydrogen ions join carbon dioxide to make glucose molecules. The other part is more important to us. This part takes up energy from sunlight and uses that to split water into hydrogen and oxygen. All this happens in a big complex of proteins and chlorophyll.

Artificial leaves
Scientists have figured a way to make a simple device that works like a leaf. One part of it will capture sunlight, and another part will transfer the energy to a cell which will split water into hydrogen and oxygen, which can be stored in tanks. When we need energy, we can put these gases in a fuel cell, where they react to form water and release electricity.

The trick is to find material that is cheap enough for building millions of such devices. These can then be put in vehicles and power plants. Right now a big search is on for finding materials to do these things.

Finding Cheap Materials
Why not directly use the chlorophyll present in leaves? That’s what a team in North Carolina State University in USA did. They extracted chlorophyll from leaves and trapped it in a transparent jelly(Petrolatum). They put tiny electrodes made of carbon nanotubes in this jelly. When sunlight falls on chlorophyll, it seizes a photon and releases an electron. The electron is carried away by the carbon nanotubes to make electricity.

This electricity can drive a cell in which water is split to form hydrogen and oxygen. For that, another team in Massachusetts Institute of technology, USA have found cheap materials to make a cell. It uses electrodes made of indium and tin oxide, and an electrolyte of cobalt and phosphorus ions. This is able to split water quite efficiently.

If we put these two parts together, we can get a cheap artificial leaf that collects energy from the sun. But it is still sometime to go before we have a small, cheap and portable device that can go into our car. But by the time you’re grown, it might be ready!

From Rotting Mushroom to Drug?

Soft rot diseases cause a great deal of damage in agriculture, and turn fruits, vegetables, and mushrooms to mush. By using imaging mass spectrometry together with genetic and bioinformatic techniques (genome mining), German researchers have now discovered the substance the bacteria use to decompose mushrooms. As the scientists report in the journal Angewandte Chemie, the substance called jagaricin could represent a starting point for the development of new antifungal drugs.

Button mushrooms with soft rot develop typical lesions and are eventually completely disintegrate. The pathogen causing soft rot in cultivated mushrooms has been identified as Janthinobacterium agarididamnosum. A team led by Christian Hertweck at the Leibniz Institute for Natural Product Research and Infection Biology in Jena (Germany) wanted to know which bacterial compound is responsible for this destruction in order to better understand the pathobiology and to find possible protective measures. If the soft rot bacteria produce a substance that attacks mushrooms, it is also conceivable that this substance could be effective against microbial fungi, which cause dangerous infections in humans.

Their challenge was to search for an unknown substance that the bacteria do not produce under standard culture conditions, but only when they attack a mushroom. Hertweck and his co-workers used a method called genome mining. They sequenced the genome of the bacterium and searched it for relevant biosynthesis genes. Using bioinformatic techniques, they made predictions about the structures of the metabolites.

The structure of jagaricin – which is what they called the substance – was fully determined using physical chemical analyses, chemical derivatization, and bioinformatics. The compound is a novel lipopeptide with an unusual structure. Pure jagaricin induces the symptoms of soft rot in mushrooms. The researchers were thus able to demonstrate that jagaricin is involved in the infectious process of the soft rot disease. Degrading enzymes presumably also participate.

The scientists also determined that jagaricin is effective against Candida albicans, Aspergillus fumigatus, and Aspergillus terreus, which cause human fungal infections. Perhaps this substance could be a starting point for the development of a new antifungal drug.

Cobalt Used As Industrial Catalyst

Cobalt(the CAS number is 7440-48-4), a common mineral, holds promise as an industrial catalyst with potential applications in such energy-related technologies such as the production of biofuels and the reduction of carbon dioxide. That is, provided the cobalt is captured in a complex molecule so it mimics the precious metals that normally serve this industrial role.

In work published Nov. 26 in the international edition of the chemistry journal Angewandte Chemie, Los Alamos National Laboratory scientists report the possibility of replacing the normally used noble metal catalysts with cobalt.

Catalysts are the parallel of the Philosopher’s Stone for chemistry. They cannot change lead to gold, but they do transform one chemical substance into another while remaining unchanged themselves. Perhaps the most familiar example of catalysis comes from automobile exhaust systems that change toxic fumes into more benign gases, but catalysts are also integral to thousands of industrial, synthetic, and renewable energy processes where they accelerate or optimize a mind-boggling array of chemical reactions.  It’s not an exaggeration to say that without catalysts, there would be no modern industry.

But a drawback to catalysts is that the most effective ones tend to be literally precious. They are the noble metal elements such as platinum, palladium, rhodium, and ruthenium, which are a prohibitively expensive resource when required in large quantities. In the absence of a genuine Philosopher’s Stone, they could also become increasingly expensive as industrial applications increase worldwide. A push in sustainable chemistry has been to develop alternatives to the precious metal catalysts by using relatively inexpensive, earth-abundant metals.

Cobalt, like iron and other transition metals in the Periodic Table, is cheap and relatively abundant, but it has a propensity to undergo irreversible reactions rather than emerging unchanged from chemical reactions as is required of an effective catalyst. The breakthrough by the Los Alamos team was to capture the cobalt atom in a complex molecule in such a way that it can mimic the reactivity of precious metal catalysts, and do so in a wide range of circumstances.

The findings of the Los Alamos team have major ramifications and suggest that cobalt complexes are rich with possibility for future catalyst development. Due to the high performance and low cost of the metal, the cobalt catalyst has potential applications in energy-related technologies such as the production of biofuels, and the reduction of carbon dioxide. It also has implications for organic chemistry, where hydrogenation is a commonly practiced catalytic reaction that produces important industrial chemical precursors.

Stopping mineral processing from turning to jelly

Cooking minerals in huge mixing tanks can turn them to jelly, and an Adelaide researcher has found out why. The work could save the industry millions of dollars a year in lost production and cleaning costs.

Sticky gel-like materials form during the liquid processing of mineral ores, when clays present in the deposits release elements such as silicon and aluminium into the liquid under particular conditions of temperature and acidity. That’s what Dr Ataollah Nosrati, a research associate at the Ian Wark Research Institute (The Wark) of the University of South Australia has found.

To extract valuable metals, some of world’s largest mineral deposits are mined and processed as concentrated slurries. This generally occurs in mixing tanks at high temperatures under aggressive acidic or alkaline conditions. Zinc silicate ores, for instance, are typically cooked at between 50 °C and 80 °C under very acidic conditions for a couple of hours.

But occasionally, the breakdown of the attached silicon compounds results in everything thickening into a gel. This kind of thing can also happen with other ores containing reactive clays or silicates.

“If we can prevent or mitigate this,” Ataollah says, “it would lead to a higher recovery rate of valuable metals, lower operating costs, and a dramatic increase in throughput with a greatly reduced number of plant shutdowns. The decreased need for cleaning the mixing tanks would also increase safety.”

“Ataollah identified and established plausible mechanisms responsible for gelation,” said Prof Jonas Addai-Mensah, Associate Director (Minerals) at The Wark. “He also proposed possible mitigation strategies in actual mineral plants for this costly and intractable issue.”

Due to their high solubility at elevated temperatures under acidic conditions, the clay-based minerals release significant amounts of gel-forming elements into the processing solution, Ataollah found. Reactions among these elements can have a significant impact on the particle interactions and flow behaviour in the solution, and that is what leads to gelling.

The research findings pave the way for enhancing our ability to process complex, low-grade ores of copper, gold, nickel and cobalt which contain silicates and aluminosilicate clays.

Ataollah Nosrati is one of 12 early-career scientists unveiling their research to the public for the first time thanks to Fresh Science, a national program sponsored by the Australian Government.

Gateway Enzyme for Chemicals from Catnip to Cancer Drug

Scientists have discovered an enzyme used in nature to make powerful chemicals from catnip to a cancer drug, vinblastine. The discovery opens up the prospect of producing these chemicals cheaply and efficiently.

They are produced naturally by some plants such as the medicinal Madagascar periwinkle, but faster-growing plants could be used to produce them. With synthetic biology, improvements could also be made to them.

The study, to be published in Nature on Thursday, was led by scientists from the John Innes Centre, an institute on Norwich Research Park strategically funded by BBSRC.

“Thousands of chemicals are derived from the enzyme we have called iridoid synthase,” says senior author Dr Sarah O’Connor from the JIC and the University of East Anglia.

“We can start to use it to come up with new-to-nature structures with biological activity of benefit to both medicine and agriculture.”

Many aphids, often important agricultural pests, produce sex pheromone chemicals that are identical to or that closely resemble the iridoid synthase product. Strategic use of these iridoid chemicals could be used to disrupt the aphids’ breeding cycle or to repel them from crops.

“We need to identify more enzymes to see the entire pathway used in nature to make this potent compound,” said Dr O’Connor. The backbone of all iridoids consists of two fused rings and scientists have been trying to track down what makes this ring system. Experiments showed that iridoid synthase is the enzyme responsible.

Scientists already knew the enzyme preceeding iridoid synthase and how the gene encoding it is expressed. The lead author, Dr Fernando Geu-Flores from JIC, therefore looked for enzymes that are encoded by genes expressed in a similar way and narrowed down their search to 20 enzymes.

Research published in the 1980s indicated that the missing enzyme is dependent on a particular compound called NADPH, which narrowed the search down to two enzymes.

O’Connor and her co-workers will also investigate whether the enzyme is important in a simple chemical reaction used by chemists for nearly 100 years. Scientists are trying to identify which enzymes catalyse a reaction called the Diels-Alder reaction, named after the Nobel prize-winning scientists who discovered it. A better understanding of how the iridoid synthase works could open up new ways to make pharmaceutical compounds using synthetic biology.

A simple way to precipitate phosphorus from the wastewater

Researchers from Aalto University have found a simple method for reducing the amount of phosphorus in the wastewater of a pulp mill. The method is called simultaneous precipitation using iron sulphate. A separate treatment stage is not required, as the precipitation takes place simultaneously with the actual biological wastewater treatment

Iron sulphate is added to the wastewater prior to the biological wastewater treatment process, and the phosphorus dissolved into the water is precipitated with the biomass at the treatment plant. Finally, the phosphorus is removed from the plant with the sludge. In Finland, sludge is generally burned, in which case the phosphorus would end up in the ashes and would thus be reusable in the form of fertilizers, for example.

“At best, the amount of phosphorus in the wastewater was reduced by more than 80 per cent, when the amount of iron fed into the process was 10 milligrams per liter,” commented researcher Sakari Toivakainen, who is currently preparing his doctoral dissertation.

Public authorities are calling for the lowering of phosphorus emissions. For this reason, many factories have adopted an additional post-treatment precipitation stage, which is usually implemented using aluminium. “Post-treatment precipitation using aluminium produces difficult-to-process sludge. On the whole, simultaneous precipitation would seem to be a more advantageous option,” Timo Laukkanen, Doctor of Science (Technology), concludes.

Initially, the research was carried out in the laboratories of Otaniemi and at the plant using pilot equipment. The results were so promising that, later on; iron precipitation was also successfully tested at the wastewater treatment section of a pulp mill.

Simultaneous precipitation does not require additional wastewater treatment units, so there is no need for additional energy in the treatment of the water, either. An additional benefit of the method is that iron sulphate is an inexpensive chemical. Wastewater from the forestry industry contains less phosphorus than municipal wastewater, so the dosage of the iron chemical remains within reasonable limits.

“From the viewpoint of comprehensive environmental protection and sustainable development, the best method is always the one that saves energy and minimises the amount of waste. With the help of the studied simultaneous precipitation method, it is possible to completely avoid additional stages of wastewater treatment, reduce the amount of solid waste and save energy.

Simultaneous precipitation produces hundreds of thousands of euros worth of savings in operating costs, as energy consumption and the need for additional chemicals is reduced,” Professor Olli Dahl crystallises.

The New Research Of Yeast Protein

 

Several fatal brain disorders, including Parkinson’s disease, are connected by the misfolding of specific proteins into disordered clumps and stable, insoluble fibrils called amyloid. Amyloid fibrils are hard to break up due to their stable, ordered structure. For example, alpha-synuclein forms amyloid fibrils that accumulate in Lewy Bodies in Parkinson’s disease. By contrast, protein clumps that accumulate in response to environmental stress, such as heat shock, possess a less stable, disordered architecture.

Hsp104, an enzyme from yeast, breaks up both amyloid fibrils and disordered clumps. In the most recent issue of Cell, James Shorter, PhD, assistant professor of Biochemistry and Biophysics, and colleagues from the Perelman School of Medicine, University of Pennsylvania, show that Hsp104 switches mechanism to break up amyloid versus disordered clumps. For stable amyloid-type structures, Hsp104 needs all six of its subunits, which together make a hexamer, to pull the clumps apart. By contrast, for the more amorphous, non-amyloid clumps, Hsp104 required only one of its six subunits.

Unexpectedly, the bacterial version of the Hsp104 enzyme, called ClpB, behaves differently compared to Hsp104. Bacterial ClpB uses all six subunits to break up amorphous clumps and fails to break up amyloid fibrils. Bacteria just ignore these more stable structures, whereas yeast use Hsp104 to exploit amyloid fibrils for beneficial purposes.

“One surprise is that biochemists thought that Hsp104 and ClpB hexamers worked in the same way,” says first author and graduate student in the Shorter lab Morgan DeSantis. “This is not the case.”

Hsp104 breaks up the protein clumps by “pulling” individual polypeptide chains through a channel that the hexamer forms at its center, recruiting more subunits to the job, as needed. Individual polypeptides emerge on the other side where they can be refolded into active structures. Remarkably, Hsp104 broke up various amyloid fibrils formed by proteins connected to Alzheimer’s disease (tau and Ab42), Parkinson’s disease (α-synuclein), Huntington’s disease (polyglutamine), and even type II diabetes (amylin).

The bad news is that animals do not harbor their own version of Hsp104 and they do not appear to have the protein machinery to break up amyloid clumps as rapidly. But Shorter views this as a possible therapeutic opportunity: “We want to introduce Hsp104 transiently as a therapeutic clump buster and optimize Hsp104 for each type of disease protein.” He is heartened by preclinical evidence that Hsp104 rescues neurodegeneration caused by α-synuclein misfolding in a rat model of Parkinson’s disease. His lab is now scanning yeast cells to look for the most useful forms of Hsp104.

What Are Octane Ratings?

Have you ever wondered about how petrol actually powers your car’s engine? Or how safe it is? Here is a closer look at the chemistry behind octane and how its rating works.

How car engines work
The engine used in your car is called an ‘internal combustion engine’. That is because it burns fuel inside the engine (a steam engine burns fuel outside to heat the steam which drives the engine).

A few drops of fuel are mixed with air and injected from the tank into the ‘combustion chamber’ of your car’s engine. The car battery then provides an electric spark. The spark causes the fuel to catch fire, making the chamber hot. The heat makes the air expand, and that in turn drives the piston which turns the wheels. A little complex isn’t it?

It’s important that the fuel catch fire safely, and not explode. If the fuel drops exploded when catching fire, that would cause ‘knocking’ in the engine. This is dangerous, for it can damage the piston and cause leakage of hot fuel into other parts of the engine. That’s why the octane rating (also called octane number) is important.

What is petrol made of
Before we understand octane number, let’s see what petrol is made of. It is a mixture of a number of organic chemicals called hydrocarbons. A hydrocarbon is a chemical compound made only of carbon and hydrogen atoms.

Iso-octane is a hydrocarbon made of eight carbon atoms and eighteen hydrogen atoms. It burns quite safely. Heptane is a hydrocarbon of seven carbon atoms, and it burns very explosively. Scientists have created a scale that measures how safely fuel burns, by comparing them with these hydrocarbons. Iso-octane is the safest (100 points) while heptane is the most dangerous (0 points).

Octane rating
Experts have made different mixtures of isooctane and heptane and burned them to create the octane scale. For example, 9 parts of iso-octane and 1 part heptane burns with a rating of 90. If a sample of petrol burns just like this mix, it will get a rating of 90. The closer it is to 100, the safer it is.

However, it is difficult and expensive to create petrol that has only iso-octane in it, because heptane is quite hard to remove. Instead, fuel experts sometimes add other chemicals that prevent the fuel mixture from exploding. These are called ‘anti-knocking agents.’ For a long time, tetra-ethyl lead was used as an additive, but it is banned now because it causes lead poisoning. Nowadays, safer anti-knock agents are used.

So next time you go to a petrol pump, do remember to ask for the octane rating of the fuel, and buy only the fuel that has a high rating.

Advancing the use of DNA in nanotechnology with new technique

Carrying the genetic code is already a vital job, but DNA is also proving to be a useful tool in nanotechnology applications. Since the DNA molecule is a versatile building block, it can be used to construct molecular devices. DNA structures known as ‘DNAzymes’ can also act as catalysts for certain chemical reactions. However, the inability to dissolve DNA in anything but water has hindered progress.

Now, DNA can be dissolved in a range of organic solvents, without destroying its folded structure, thanks to a discovery by Hiroshi Abe, Yoshihiro Ito and their colleagues at the RIKEN Advanced Science Institute, Wako.

The researchers showed that DNA will dissolve in most organic solvents after attaching a long side chain called a polyethylene glycol (PEG) unit. Organic solvents are typically much less polar than water, which prevents polar DNA molecules from dissolving in them. By attaching a non-polar PEG group to one end of a DNA strand, they were able to dissolve it in organic solvents ranging from methanol to 1,2-dichloroethane—solvents that scientists usually use for chemical reactions because many molecules are water-sensitive.

The team used an analytical technique called circular dichroism to show that a series of PEG-modified DNA structures called G-quadruplexes retain their shape in the organic solvents. Other teams had successfully dissolved DNA in an organic solvent by simply pre-mixing it with another non-polar substance, but the process caused the DNA to lose its folded shape, Abe notes. “The PEG-modification allows us to keep the structure of DNA intact in organic solvents,” he says.

Surprisingly, one of the PEG-modified G-quadruplex structures tested by the researchers proved to be more stable in organic solvents than it is in water. While some of the forces that hold the DNA structure in its folded shape are weaker in the non-polar organic solvent, others, such as hydrogen bonding interactions, are strengthened, Abe explains.

Crucially, the retention of DNA’s structure in organic solvents means that it can also retain its ability to function as a catalyst, for example. In water, the PEG-modified version of a G-quadruplex DNAzyme named HT6 oxidizes a molecule called luminol (the CAS number is 521-31-3 and also known as 3-Aminophthalhydrazide) into a light-emitting form. When the researchers switched to an organic solvent, a tell-tale luminescent glow confirmed that the DNAzyme was still functioning.

Abe, Ito and colleagues are now focused on generating organic-solvent-soluble DNAzymes with more useful catalytic functions. They are using a technique called SELEX to generate libraries of DNAzymes tailor-made to work in organic solvents.

Next-generation Device Enabling Improved Smartphone Battery Life

A research by Japan’s NIMS International Center for Materials Nanoarchitectonics has succeeded in developing a metal oxide film transistor using a material with an unique atomic composition.

Metal oxide film transistors are an object of research and technical development as next-generation materials for amorphous silicon transistors, which are used to switch picture elements (pixels) in the flat panels of existing televisions, computers, smartphones, and similar products. In current displays using amorphous silicon transistors, power consumption is increasing rapidly due to new high resolution and touch panel features. As there are limits to improvement of the properties of the conventional material, new materials are considered necessary as an alternative to amorphous silicon thin films.

In recent years, it has been found that IGZO film transistors, which are produced from a mixed target obtained by oxidizing indium, gallium, and zinc, operate with high electron field effect mobility. Although process development is underway aiming at development to practical applications, control of oxygen and moisture is extremely difficult with this material. Therefore, development of techniques for controlling these factors had become an issue for production of transistors using a metal oxide film as a semiconductor thin film.

To solve this problem, materials that enable transistor operation with novel metal oxide films consisting of easily-handled atoms had been the object of an ongoing search.

In this research, an IWO (indium-tungsten oxide) thin film that operates as a thin film transistor was developed by adding an extremely small amount of tungsten oxide to indium oxide (its chemical formula is In2O3). The developed material does not contain gallium or zinc, which are elements that are difficult to control in an amorphous state. Because a homogeneous amorphous film can be produced simply by sputter film-forming at low energy, without heating the substrate or similar operations, thin films are easily formed with this new material, and operation as a transistor with high characteristics is possible, even using a structure without a protective film with an unprecedented thin film thickness of 10nm. In addition to avoiding use of expensive gallium, the thin structure is also effective in reducing material costs because the total amount of raw materials used in the thin film can be reduced, and also enables high production efficiency.

This achievement will be effective in realizing low power consumption in displays, which are a source of high power consumption in smartphones, thereby responding to an important need in a field that is currently enjoying explosive growth. It is also expected to be an effective technology for frequency improvement, which is essential for higher resolution in televisions.