3D print operational drone with embedded electronics using aerospace-grade material

Researchers at Nanyang Technological University, Singapore (NTU Singapore) have 3D printed a ready-to-fly drone with embedded electronics using aerospace-grade material. The electronics were incorporated in the drone during the 3D printing process which employs Stratasys ULTEMTM 9085 -- a high strength, lightweight FDM material certified for use in commercial aircrafts. The drone is jointly developed by NTU's Singapore Centre for 3D Printing (SC3DP) and Stratasys Asia Pacific, a subsidiary of Stratasys Ltd. (NASDAQ: SSYS), a 3D printing and additive manufacturing solutions company. How the Flight-Ready Drone was Built The drone -- a quadcopter with four rotors -- was designed, 3D printed and flown by Mr Phillip Keane, an NTU PhD candidate from the School of Mechanical and Aerospace Engineering who researches at the university's Singapore Centre for 3D Printing (SC3DP). In 3D printing, objects are created digitally layer by layer until completion. However, embedding electronics can be a challenge, as most will not survive the high temperatures of the 3D printing process. Commercial grade electronics were therefore modified and placed within the drone at the various stages of the printing process. They survived the high temperature printing which reached over 160 degrees Celsius, compared to the usual 80 to 100 degrees. Only the motors and the propellers were mounted after the entire chassis was completed. Mr Keane said: "One of the toughest challenges was to find electronic components that could theoretically survive the high temperature printing process -- we had to add some heat-proofing modifications to the components to ensure they could last. This involved adding new components to the printed circuit boards and also designing custom housings." The drone was completed in under 14 hours. During the printing, there were just three pauses for the electronics to be placed within the chassis. "The housings which were pre-printed in ULTEM 9085 also provide a flat surface for the 3D printer to continue printing over them. I also had to deal with tight time constraints as some of the components could not survive in the heat for more than 20 minutes." In addition to being extremely rugged, the drone is capable of supporting over 60kg of weight suspended from its structure. Moving forward, Mr Keane said he is working on the next version of the drone which will feature better durability, lighter weight and improved flight dynamics. Professor Chua Chee Kai, Executive Director of NTU's SC3DP said that this is a successful example of disruptive innovation that can be achieved when researchers from academia work with industry partners. "At NTU, we have world leading researchers with vast knowledge of materials and 3D printing processes whohave invented innovative techniques to overcome the limitations of existing technologies," explained Prof Chua, the world's most cited scientist in the field of 3D printing according to the Web of Science, a research database maintained by Thomson Reuters. "Together with Stratasys' engineers and their intimate knowledge of 3D printing, we were able to push the limits of today's technology and print a drone that is incredibly durable and can withstand high heat." "This project exemplifies the power of Stratasys' flagship Fused Deposition Modeling (FDM) 3D printing technology and perfectly demonstrates the strength of the ULTEM resin," commented Fred Fischer, Director -- Applications and Products, Stratasys Asia Pacific. "We look forward to researching, developing and unveiling more possibilities with 3D printing and materials as we work with industry partners and academia." ULTEM 9085 is a production-grade thermoplastic that can be 3D printed and is prized for a high strength-to-weight ratio and FST (flame, smoke and toxicity) rating, making it ideal for the commercial transportation industry, especially aerospace. Professor Louis Phee, Chair, School of Mechanical and Aerospace Engineering at NTU, said that unmanned aerial vehicles (UAV) are a major research thrust at the school. "Being the first university in Singapore to offer an Aerospace Engineering degree programme, we have been successful in attracting the brightest students to work with our professors to push the frontiers of drone technologies to cater to Singapore's unique needs and requirements. In the near future, I expect to see more exciting new drone technologies from NTU that will be translated into real applications."     Source:Nanyang Technological University    

Who needs a body? Not these larvae, which are basically swimming heads

Graduate student Paul Gonzalez at Stanford University's Hopkins Marine Station recently became a hunter, breeder and farmer of a rare marine worm, all to fill in a considerable gap in our understanding of how animals develop. He knew that some animals go through a long larval stage, a developmental strategy known as indirect development, and this rare worm was his chance to better understand that process. What Gonzalez and his colleagues found was that the worms go through a prolonged phase with little more than head. This work, published in the Dec. 8 issue of Current Biology, suggests that many animals in the ocean likely share this trunk-less stage, and it may even shed light on the biological development of early animals. "Indirect development is the most prevalent developmental strategy of marine invertebrates and life evolved in the ocean," said Chris Lowe, senior author of the paper and associate professor of biology. "This means the earliest animals probably used these kinds of strategies to develop into adults." Most research animals commonly found in labs, such as mice, zebrafish and the worm C. elegans, are direct developers, species that don't go through a distinct larval stage. To understand how indirect developers differ from these, Gonzalez needed to study an indirect developer that was very closely related to a well-studied direct developer. His best bet was a group of marine invertebrates called Hemichordata because there is already a wealth of molecular developmental work done on direct developers in this group. A flaw in this plan was that the indirect developers in this phylum were uncommon in areas near the station. Undeterred, Gonzalez poured through marine faunal surveys until a 1994 study gave him his big break: Schizocardium californicum, a species of acorn worm and indirect developer in the Hemichordata phylum, was once in Morro Bay, only two hours away. Through contacting the researchers from that decades-old paper, Gonzalez obtained the exact coordinates of the worms. Once there, he pulled on a wet suit, readied his shovel and began his hunt for the odd-looking ocean-dwellers. Diversifying the study of diversity Direct developers are more often used in research largely for reasons of practicality. "Terrestrial, direct developing species develop fast, their life cycle is simple and they are easy to rear in the lab," said Gonzalez, who was lead author of the paper. By comparison, indirect developers develop slowly, have a long larval stage, and their larvae are difficult to feed and maintain in captivity. The reproductive adults are also challenging to keep in the lab and, as Gonzalez has shown, collecting them can be an arduous process. However, the relative ease of studying direct developers has made for a lack of diversity in what scientists know about evolution and development, Gonzalez said. "By selecting convenient species, we select a non-random sample of animal diversity, running the risk of missing interesting things," he said. "That's what brought me to the Lowe lab. We specialize in asking cool evolutionary questions using developmental biology and molecular genetics, and we're not afraid to start from scratch and work on animals that no one has worked with before." Swimming heads After spending months perfecting the rearing and breeding techniques needed to study these worms, the researchers were eventually able to sequence the RNA from various stages of the worm's development. They did this in order to see where specific genes are turned on or off in an embryo. They found that in the worms, activity of certain genes that would lead to the development of a trunk are delayed. So, during the larval stage, the worms are basically swimming heads. "When you look at a larva, it's like you're looking at an acorn worm that decided to delay development of its trunk, inflate its body to be balloon-shaped and float around in the plankton to feed on delicious algae," said Gonzalez. "Delayed trunk development is probably very important to evolve a body shape that is different from that of a worm, and more suitable for life in the water column." As they continue to grow, the acorn worms eventually undergo a metamorphosis to their adult body plan. At this point, the genes that regulate the development of the trunk activate and the worms begin to develop the long body found in adults, which eventually grows to about 40 cm (15.8 inches) over the span of several years. Just the beginning Even with such a fascinating result, this research is only the beginning of the Lowe lab's examination of indirect developers. These worms will never tell us about human diseases, unlike work with stem cells or mice, but they could reveal the intricacies of how life works for many organisms beyond the model species that we've studied so heavily. They may also show us how life in general came to be what it is today. "Given how pervasive larvae are in the animal world, we understand very little about this critical phase in animal development," said Lowe. "These are not the kind of species you want to pick if you want deep, mechanistic insights into developmental biology. But, if your goal is to understand how animals have evolved, then you cannot avoid using these species." Next, the researchers want to figure out how the acorn worm body development delay happens. They also have begun to sequence the genome of S. californicum.     Source:Stanford University

'Bickering' flies make evolutionary point

When a male fruit fly gets aggressive, he rears up on his back four legs and batters his foe with his front pair. Neither fly seems particularly damaged by the encounter, but their subsequent actions are telling about the ways of social evolution, according to Rice University evolutionary biologist Julia Saltz. Saltz went to the fruit fly fights every day for months to find out how the creatures' genotypes -- the genetic code that determines what they are -- affect their phenotypes -- the characteristics they present to their fellow flies. In doing so, she bolstered the longstanding hypothesis in psychology that individuals are not merely subject to their social environments, but choose and create them through their interactions. By placing genetically distinct variants of flies in various and sometimes uncomfortable situations, Saltz observed their behavior under stress and how stress altered the behavior of interacting individuals -- a process called social-environment construction -- when the "stressed" fly was moved to a new group for further observation. "The main takeaway is that individuals' behaviors affect their social environments," she said. "In other words, when you pick your friends, it matters to you and it affects both what happens in the group and your behavior at a later time." The study appears in the Nature journal Heredity. Saltz, an assistant professor of biosciences, said few have undertaken direct studies of social-environment construction because of the difficulty involved. "You can't do it with people," she said, noting that it would be "unwise" to send someone into a room of subjects and have that person punch another. But fruit flies are a worthy substitute, as both their genetic traits and environments can be manipulated easily, Saltz said. Saltz, sole author of the paper, observed focal males -- her primary subjects -- either alone or with small groups of 2 to 8 fruit flies over two days in each experiment. (They totaled 1,300 flies over many months.) She placed genetically identical pairs in either their preferred or nonpreferred environments -- either large or small groups -- and measured their aggressive behaviors. She noted different genotypes of fly have different group-size preferences, allowing for variation among the experiments. In the first stage of the study, she determined the preferences of focal males by genotype for group size. In the second stage, over hundreds of experiments, she put individual focal males into various-sized groups of "stimulus" flies. "For day one, I put a 'genotype one' focal male with a group of flies, and a 'genotype two' with a replica group with the same sex ratio, number and genotype, reared under standard lab conditions," she said. "That way, I knew the social environment was the same for both focal males. If there was something different about how the groups behaved, it had to be due to the genotype of that one extra male. "Arguably, the focal male would influence the behavior of other individuals in the group, which is what we saw," Saltz said. She said males in their preferred groups were attacked more frequently than those in nonpreferred groups. "We don't totally know why that is, but we can say for sure the combination of that male's genotype and its preference caused the other males to act more aggressively toward it." On day two, Saltz took the focal males -- dabbed with yellow paint to identify them -- from their initial groups and put each with a single "naïve" male in a petri dish "arena" and found the previous day's experience made them less aggressive. That may show what Saltz called the "loser" effect, in which males who lose an initial encounter are less aggressive in subsequent encounters. "That seems to be true here, except that there's no good definition of losing," she said. "That's why I like to think of it as being attacked more often." Saltz noted the flies display other types of aggression, and they may also pass chemical signals that are relevant in social environments. But lunging attacks were easiest to measure. "It's an open question of how damaging aggression is to flies, but they seem totally fine after, so it's not like they can kill another male and then get all the food," she said. "There are subcomponents of aggression that are slightly ambiguous, but for this study I measured lunging, which doesn't look like any other behavior. "The male actually rears up. The front two legs and part of its body go up and it slams its legs onto another male. It's not ambiguous, and a male can only lunge at one other male at a time, so you know exactly who was being aggressive and who was the recipient." Saltz said future studies involving larger sets and more genotypes should help show how behavior and evolutionary fitness are affected by group size and composition. She also noted studying fruit flies for two days out of their average 70-day lifespans (for lab-reared flies) is inherently limited, because it doesn't account for long-term or permanent effects.     Source:Rice University  

Science for sweet tooths

Food scientists at the University of British Columbia have developed a faster and cheaper way to quantify antioxidant levels in chocolate. It's a method they plan to use in new research to help uncover when antioxidant levels rise and fall during the manufacturing process, from raw cocoa beans to chocolate bars. "Our method predicts the antioxidant levels in chocolate in under a minute, compared to the industry standard that can take several hours or even days," said Xiaonan Lu, an assistant professor in food, nutrition and health in the faculty of land and food systems, who developed the method alongside PhD student Yaxi Hu. "It's not a substitute for the traditional method used at the moment, but it does show a strong correlation for being just as reliable." The UBC method uses infrared spectroscopy, a technology that can be used to illuminate infrared light onto chocolate samples. The infrared spectra record the chemical composition of each sample, including the amount of polyphenols, micronutrients with high antioxidant properties. The traditional method relies on biochemical tests to read absorbance values and can be quite time consuming and expensive. "Testing for antioxidant levels can give chocolatiers guidance on which cocoa beans to select, or how to improve their processing parameters," said Hu. Chocolate is made from cocoa beans and is manufactured through several processing stages, including drying, roasting and fermentation of the beans. The UBC food scientists have started to use their method to measure cocoa bean samples from around the world in each stage to determine when antioxidant levels are at their highest and lowest. "If we identify drying as the step that significantly lowers the bean's antioxidant properties, for example, we will want to develop a strategy to reduce the drying time, or drying temperature," Lu said. It could be considered incredibly valuable information for chocolate companies who want to make products high in antioxidants or appeal more to health-conscious consumers. Antioxidants benefit human health and help contribute to the prevention of cancers, vision loss and heart diseases. Antioxidant compounds are commonly found in foods like pecans, blueberries and chocolate. Lu and Hu's research on cocoa beans is in its early stages as they test hundreds of samples. The method they developed to test for antioxidant levels was funded by a local chocolatier in Metro Vancouver, the Natural Sciences and Engineering Research Council (NSERC) and by the non-profit MITACS. The UBC food scientists hope to attract additional funding, particularly from a major chocolate company, to further their studies. Parts of their existing research were published earlier this year in a study, "Determination of antioxidant capacity and phenolic content of chocolate by attenuated total reflectance-Fourier transformed-infrared spectroscopy," in the journal Food Chemistry.     Source:University of British Columbia  

Why do some STEM fields have fewer women than others? Study may have the answer

Women's relative lack of participation in science, technology, engineering and math is well documented, but why women are more represented in some STEM areas than others is less clear. A new University of Washington study is among the first to address that question by comparing gender disparities across STEM fields. Published Oct. 12 in the journal Psychological Bulletin, the paper identifies three main factors driving the disparity -- and the most powerful one, the researchers conclude, is a "masculine culture" that makes many women feel like they don't belong. "There is widespread knowledge that women are underrepresented in STEM, but people tend to lump STEM fields together," said lead author Sapna Cheryan, a UW associate professor of psychology. "This is one of the first attempts to really dig down into why women are more underrepresented in some STEM fields than others." Women now earn about 37 percent of undergraduate STEM degrees in the United States, but their representation varies widely across those fields. Women receive more than 40 percent of undergraduate degrees in math, for example, but just 18 percent of degrees in computer science. The UW study focused on six of the largest science and engineering fields with the most undergraduate degrees: biology, chemistry and math, which have the highest proportions of female participation, and computer science, engineering and physics, which have bigger gender gaps. The researchers analyzed more than 1,200 papers about women's underrepresentation in STEM, and from those identified 10 factors that impact gender differences in students' interest and participation in STEM. Then they winnowed the list down to the three factors most likely to explain gendered patterns in the six STEM fields -- a lack of pre-college experience, gender gaps in belief in one's abilities and a masculine culture that discourages women from participating. The paper identifies three main aspects of that masculine culture: stereotypes of the fields that are incompatible with how many women perceive themselves, negative stereotypes about women's abilities and a dearth of role models. Those factors decrease women's interest in a field by signaling that they do not belong there, the researchers write. A lack of pre-college experience is also a factor, the paper finds. The gender gap in STEM interest is smaller among high school seniors at schools with stronger math and science offerings, the researchers note. But courses in computer science, engineering and physics are less likely to be offered and required in U.S. high schools than courses in biology, chemistry and mathematics -- leaving students with little information about what those fields are like and who might be suited for them. "Students are basing their educational decisions in large part on their perceptions of a field," Cheryan said. "And not having early experience with what a field is really like makes it more likely that they will rely on their stereotypes about that field and who is good at it." A lack of experience does not itself cause women's underrepresentation in STEM, the researchers write. Women are attracted to many fields that students are typically not exposed to before college, such as nursing and social work, the researchers note. But when a lack of early experience is accompanied by a masculine culture, the gender proportion skews male. Early learning opportunities in STEM, Cheryan said, will only attract girls if they convey that girls belong in those fields as much as boys do. "If we're not providing students with a welcoming culture, these efforts are not likely to succeed," she said. Belief in one's abilities was a common theme in previous studies and may help explain current gender gaps, but Cheryan said inconsistent findings made it a less compelling factor. For example, she said, girls tend to report less confidence in their math abilities than boys, but the field of math is still relatively gender-balanced. Similarly, Cheryan said, gender discrimination in hiring and other opportunities was not able to explain current patterns of variability. The researchers expected to find less discrimination in the fields with higher female representation, she said, but discovered that it differed little across the six areas. The researchers embarked on the study focusing primarily on women's choices, Cheryan said, but quickly realized that explaining women's underrepresentation required also looking at men's choices. The proportion of women receiving computer science degrees, for example, has declined steadily since the mid-1980s, due more to an influx of men to the field than a drop in women's participation. Cultural historians attribute the shift to the advent of the personal computer and an accompanying stereotype of the nerdy male computer genius. "When we drilled down into the numbers, we realized that if we just looked at women, that wouldn't tell the whole story," Cheryan said. "Underrepresentation is shaped just as much by what men are doing as by what women are doing." The researchers conclude that a more inclusive culture across STEM fields is the most effective way to boost female participation. That can be achieved, Cheryan said, by developing "subcultures" that make girls feel they belong, whether that involves changing classroom décor to create a more welcoming environment or counteracting negative stereotypes about women's abilities by making it clear that everyone has the potential to succeed. "Cultural change is never easy, but there are lots of examples of it being done successfully, and it translates into changing who's in a particular field," she said.       Source:University of Washington  

Highly efficient genome engineering in flowering plants

A pair of plant biologists at the Institute of Transformative Bio-Molecules (ITbM) of Nagoya University, has reported in the journal Plant and Cell Physiology, on the development of a new vector (a carrier to transfer genetic information) to knockout the target genes in the model plant, Arabidopsis thaliana, in a highly efficient and inheritable manner. The genome consists of the organism's complete set of DNA, including its genes, which contains all the information needed to develop and maintain the organism. Genome engineering, which involves specific modification of parts of the genome by removing, adding and altering sections of the DNA sequence, is a rapidly developing technique. So far, the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 (CRISPR-associated protein 9) system is one of the most popular methods for genetic manipulation arising from its simplicity, versatility and efficiency. Nonetheless, the mutation inducing efficiency of CRISPR/Cas9 towards the model plant, Arabidopsis thaliana, has remained somewhat low so far. This is because the trigger for gene mutation is activated at later developmental stages in cells. Therefore, a significant amount of time, effort and plant species has been required to obtain the desired plant species with the targeted gene knocked out. CRISPR/Cas9 consists of 2 key molecules, a piece of RNA called guide RNA (gRNA) and an enzyme called Cas9. Cas9 acts as a molecular scissor that can cut both strands on DNA at a specific location in the genome, so that DNA sequences can be added or removed at that position. On the other hand, the gRNA consists of a pre-designed RNA sequence (about 20 bases long) that is located within a longer RNA scaffold. The RNA scaffold binds to DNA and the pre-designed RNA sequence guides the Cas9 protein to the specific part of the genome, so that Cas9 can cut at the targeted position. "By using a promoter for a RIBOSOMAL PROTEIN S5A (RPS5A) gene, which is expressed from an early embryonic stage in plant cells, we were able to induce the Cas9 protein to knockout genes in egg cells with high efficiency," says Hiroki Tsutsui, the first author of this study. "This RPS5A promoter is active in egg cells and we decided to call this molecular tool, a pKAMA-ITACHI Red (pKIR) vector, which can edit the plant's genome in high efficiency relative to the 35S promoter commonly used in plants," he continues. 'Kama-itachi' has the Japanese meaning of three weasel-like creatures, where the first weasel targets and trips a person, followed by the second one injuring the person by cutting them, and the third one healing the person. This is similar to the process of the CRISPR/Cas9 system towards DNA, where CRISPR targets, Cas9 cuts, and induces repair of the specific DNA sequence of interest. "By being able to efficiently knockout the targeted gene in Arabidopsis thaliana, we consider this to be a promising method to elucidate the genetic functions of plants," says Tetsuya Higashiyama, a Professor and leader of this research. "We hope that we can apply this methodology for genome editing of crops, such as Brassica napus, to accelerate their growth and generate a variety of plant lines." The CRISPR/Cas9 system works by knocking out a specific gene in order to investigate their function. In the model plant, Arabidopsis thaliana, as the Cas9 protein is expressed at a later developmental stage of the cell, the degree of gene knockout varies according to the tissue. The genome mutation efficiency has therefore been relatively low. For instance, when a commonly used 35S promoter for plants was used to express the Cas9 protein in Arabidopsis thaliana, although frequent knockouts of the genes were observed in the leaves, only a few were detected in flowers. This suggests that the knockout mutation efficiency of the target gene was relatively low in the reproductive cells of flowers. Subsequently, the knockout mutation was difficult to be passed on to the daughter cells in the next generation. In order to solve this issue, Higashiyama's group decided to express the Cas9 protein in the egg cell and in the cell during the early developmental stage, in order to improve the knockout efficiency of the genes. "Since egg cells and fertilized egg cells (zygotes) are the origin for plant cells to develop and grow, we figured that if genome editing is carried out at an early stage, gene mutation may occur with high efficiency and can be inherited by the next generation of cells," explains Tsutsui. "The pKIR vector was ideal as it can continuously express the Cas9 protein during the egg cell stage and the developmental stage." The team first attempted the knockout of the PDS3 (Phytoene DeSaturase 3) gene, which is known to be responsible for the synthesis of chlorophyll in plants. Without chlorophyll, the plant will become an albino species with a white appearance. By expressing Cas9 with pKIR, Tsutsui succeeded in observing the knockout of the PDS3 gene, indicated by the generation of an albino plant. Tsutsui also investigated the effect on the amount of chlorophyll synthesized in the flower stem, when the PDS3 gene was knocked out. Upon use of the 35S promoter to express Cas9, the amount of chlorophyll was only slightly different to the amount observed in the wild type. On the other hand, when Cas9 was induced by pKIR, the amount of chlorophyll decreased drastically, suggesting that knockout of the gene had occurred efficiently. The team also found that the pKIR vector successfully knocks out other genes in Arabidopsis thaliana, such as AGAMOUS (AG), DUO1 (DUO POLLEN 1), and ADH1 (ALCOHOL DEHYDROGENASE 1), which are involved in the development of the flower, sperm cell, and an enzyme that converts alcohol to aldehydes, respectively. AGAMOUS is a transcription factor involved in flower development (floral meristem). Upon knockout of the AGAMOUS gene induced by pKIR, a flower within a flower, known as a double flower was observed in high frequency. In addition, in the knockout experiment of DUO1 gene, which encodes a male germ line, induced by pKIR, cell division of the generative cell was impaired and a non-fertile sperm-like cell was observed. The ADH1 gene, which encodes an enzyme that converts allyl alcohol into acrolein (an aldehyde), was also knocked out by induction with pKIR in high frequency. This high frequency suggests that the ADH1 gene was knocked out in all of the reproductive cells (egg and sperm cells) in the first generation. Mutants with the ADH1 gene knockout were able to survive, while the wild type and heterozygous plants were killed due to the generation of acrolein, which is toxic for plants. "Since all of the species in the second generation showed the same mutation pattern, this indicates that genome editing had occurred early in the developmental stage (in the egg cells of the first generation)," describes Tsutsui. In order to easily identify the species installed with genes for CRISPR/Cas9, the seeds that contain Cas9 are marked by red fluorescence. Tsutsui and Higashiyama have found an efficient method for genome editing of Arabidopsis thaliana, which consists of expressing Cas9 with a RPS5A promoter (pKIR vector) that can knockout the genes in cells during an early developmental stage and induce mutations that can be passed on to the daughter cells in the next generation. "This pKIR method allows us to investigate gene clusters, which may have overlapping functions," says Tsutsui. "Previously, we had to make multiple knockout plants by crossing existing mutants to examine overlapping gene functions, which took time. We should be able to explore the functions of unidentified gene clusters by being able to rapidly access mutants by our relatively low cost method." "We hope we can continue to improve this method to increase the mutation efficiency, so that it becomes a useful genome engineering tool for modifying the target DNA sequences in various organisms," says Higashiyama.     Source:Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University

Perovskite solar cells hit new world efficiency record

They're flexible, cheap to produce and simple to make -- which is why perovskites are the hottest new material in solar cell design. And now, engineers at Australia's University of New South Wales in Sydney have smashed the trendy new compound's world efficiency record. Speaking at the Asia-Pacific Solar Research Conference in Canberra on Friday 2 December, Anita Ho-Baillie, a Senior Research Fellow at the Australian Centre for Advanced Photovoltaics (ACAP), announced that her team at UNSW has achieved the highest efficiency rating with the largest perovskite solar cells to date. The 12.1% efficiency rating was for a 16 cm2 perovskite solar cell, the largest single perovskite photovoltaic cell certified with the highest energy conversion efficiency, and was independently confirmed by the international testing centre Newport Corp, in Bozeman, Montana. The new cell is at least 10 times bigger than the current certified high-efficiency perovskite solar cells on record. Her team has also achieved an 18% efficiency rating on a 1.2 cm2 single perovskite cell, and an 11.5% for a 16 cm2 four-cell perovskite mini-module, both independently certified by Newport. "This is a very hot area of research, with many teams competing to advance photovoltaic design," said Ho-Baillie. "Perovskites came out of nowhere in 2009, with an efficiency rating of 3.8%, and have since grown in leaps and bounds. These results place UNSW amongst the best groups in the world producing state-of-the-art high-performance perovskite solar cells. And I think we can get to 24% within a year or so." Perovskite is a structured compound, where a hybrid organic-inorganic lead or tin halide-based material acts as the light-harvesting active layer. They are the fastest-advancing solar technology to date, and are attractive because the compound is cheap to produce and simple to manufacture, and can even be sprayed onto surfaces. "The versatility of solution deposition of perovskite makes it possible to spray-coat, print or paint on solar cells," said Ho-Baillie. "The diversity of chemical compositions also allows cells be transparent, or made of different colours. Imagine being able to cover every surface of buildings, devices and cars with solar cells." Most of the world's commercial solar cells are made from a refined, highly purified silicon crystal and, like the most efficient commercial silicon cells (known as PERC cells and invented at UNSW), need to be baked above 800?C in multiple high-temperature steps. Perovskites, on the other hand, are made at low temperatures and 200 times thinner than silicon cells. But although perovskites hold much promise for cost-effective solar energy, they are currently prone to fluctuating temperatures and moisture, making them last only a few months without protection. Along with every other team in the world, Ho-Baillie's is trying to extend its durability. Thanks to what engineers learned from more than 40 years of work with layered silicon, they're are confident they can extend this. Nevertheless, there are many existing applications where even disposable low-cost, high-efficiency solar cells could be attractive, such as use in disaster response, device charging and lighting in electricity-poor regions of the world. Perovskite solar cells also have the highest power to weight ratio amongst viable photovoltaic technologies. "We will capitalise on the advantages of perovskites and continue to tackle issues important for commercialisation, like scaling to larger areas and improving cell durability," said Martin Green, Director of the ACAP and Ho-Baillie's mentor. The project's goal is to lift perovskite solar cell efficiency to 26%. The research is part of a collaboration backed by $3.6 million in funding through the Australian Renewable Energy Agency's (ARENA) 'solar excellence' initiative. ARENA's CEO Ivor Frischknecht said the achievement demonstrated the importance of supporting early stage renewable energy technologies: "In the future, this world-leading R&D could deliver efficiency wins for households and businesses through rooftop solar as well as for big solar projects like those being advanced through ARENA's investment in large-scale solar." To make a perovskite solar cells, engineers grow crystals into a structure known as 'perovskite', named after Lev Perovski, the Russian mineralogist who discovered it. They first dissolve a selection of compounds in a liquid to make the 'ink', then deposit this on a specialised glass which can conduct electricity. When the ink dries, it leaves behind a thin film that crystallises on top of the glass when mild heat is applied, resulting in a thin layer of perovskite crystals. The tricky part is growing a thin film of perovskite crystals so the resulting solar cell absorbs a maximum amount of light. Worldwide, engineers are working to create smooth and regular layers of perovskite with large crystal grain sizes in order to increase photovoltaic yields. Ho-Baillie, who obtained her PhD at UNSW in 2004, is a former chief engineer for Solar Sailor, an Australian company which integrates solar cells into purpose-designed commercial marine ferries which currently ply waterways in Sydney, Shanghai and Hong Kong. The Australian Centre for Advanced Photovoltaics is a national research collaboration based at UNSW, whose partners are the University of Queensland, Monash University, the Australian National University, the University of Melbourne and the CSIRO Manufacturing Flagship. The collaboration is funded by an annual grant from ARENA, and partners include Arizona State University, Suntech Power and Trina Solar.     Source:University of New South Wales    

'Water Battery': Charging water by means of a mini water bridge

Together with the Wetsus research centre in The Netherlands, researchers of TU Graz have managed to produce electrically charged water by means of a floating water bridge. Until its scientific rediscovery in 2007 at TU Graz, the "water bridge" phenomenon, discovered in the 19th century, had sank into oblivion. If extremely pure water, in other words water that has been distilled many times, is placed in two beakers and subject to a high voltage, the fluid moves up the side of each beaker and forms a floating water bridge between the two vessels. The water in this bridge flows in both directions and is in a completely new state with its own special properties of density and structure. A research group of TU Graz and the Wetsus research centre in The Netherlands has now demonstrated that this floating water bridge produces electrically charged water and stores the charge at least for a short time. Protonic electrical charge The water is not electronically, but rather protonically charged. This novel kind of water is either positively or negatively charged depending on whether it contains more or fewer protons. The study shows that in anodic water -- water with a positive charge -- protons are formed in the context of the occurring electrolysis. These hydrogen nuclei flow through the water bridge into the cathodic water of the other beaker, which has a negative charge, and are neutralised there by hydroxyl ions. Since the protons move at a finite speed, there is always an excess of protons in one water container and a lack of protons in the other. If the water bridge is suddenly switched off, the proton charges remain, as can be measured by means of impedance spectroscopy. The first investigations have shown that the fluid's charge remains stable for one week. From water battery to low-waste chemistry The realisation that such water bridges can be used as electrochemical or biochemical reactors opens up a variety of possible industrial applications. Substances can be brought into contact with other materials in the water bridge for the purpose of chemical reactions, water can become a "water battery" as a storage of electric charge, and acids and alkalis can be produced without any opposing ions -- without acid and alkaline water. This opens the way to especially eco-friendly cleaning agents, reduced waste from chemical processes, and new possibilities for medical applications.   Source:TU Graz
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