Charles McLaren, a Ph.D. candidate in materials science and engineering at Lehigh, arrived last fall for a semester of research at the University of Marburg in Germany with his language skills lagging significantly behind his scientific prowess.
“It was my first trip to Germany, and I barely spoke a word of German,” he confessed.
With the help of his new German colleagues, he got past the point-and-eat phase of the international experience in no time. “The group members there were very welcoming. They showed me around and helped me learn enough vocabulary to order some food, at least.”
The main purpose of McLaren’s exchange study in Marburg was far from culinary, however. He was there to learn more about a complex process involving transformations in glass that occur under intense electrical and thermal conditions. New understanding of these mechanisms could lead the way to more energy-efficient glass manufacturing, and even glass supercapacitors that leapfrog the performance of batteries now used for electric cars and solar energy.
“This technology is relevant to companies seeking the next wave of portable, reliable energy,” said Himanshu Jain, the T. L. Diamond Distinguished Chair in Materials Science and Engineering at Lehigh and director of its International Materials Institute for New Functionality in Glass.
“A breakthrough in the use of glass for power storage could unleash a torrent of innovation in the transportation and energy sectors, and even support efforts to curb global warming.”
In his doctoral research, McLaren discovered that applying a direct current field across glass reduced its melting temperature. In lab experiments, he and Jain placed a block of glass between a cathode and anode, and then exerted steady pressure on the glass while gradually heating it. Together with colleagues at the University of Colorado, the Lehigh researchers reported their results last fall in Applied Physics Letters.
The implications for the finding were intriguing. In addition to making glass formulation possible at lower temperatures and reducing energy needs, designers using electrical current in glass manufacturing would have a tool to make precise manipulations not possible with heat alone.
“You could make a mask for the glass, for example, and apply an electrical field on a micron scale,” said Jain. “This would allow you to deform the glass with high precision, and soften it in a far more selective way than you could with heat, which gets distributed throughout the glass.”
Though McLaren and Jain had isolated the phenomenon and determined how to dial up the variables for optimal results, they did not yet fully understand the mechanisms behind it. McLaren and Jain had been following the work of Bernard Roling at the University of Marburg, who had discovered some remarkable characteristics of glass using electro-thermal poling, a technique that employs both temperature manipulation and electrical current to create a charge in normally inert glass. The process imparts useful optical and even bioactive qualities to glass.
Roling invited McLaren to spend a semester at Marburg to analyze the behavior of glass under electro-thermal poling, to see if it would reveal more about the fundamental science underlying what McLaren and Jain had observed in their Lehigh lab.
A high-speed avalanche
McLaren’s work in Marburg revealed a two-step process in which a thin sliver of the glass nearest the anode, called a depletion layer, becomes much more resistant to electrical current than the rest of the glass as alkali ions in the glass migrate away. This is followed by a catastrophic change in the layer, known as dielectric breakdown, which dramatically increases its conductivity. McLaren likens the process of dielectric breakdown to a high-speed avalanche, and uses spectroscopic analysis with electro-thermal poling as a way to see what is happening in slow motion.
“The results in Germany gave us a very good model for what is going on in the electric field-induced softening that we did here. It told us about the start conditions for where dielectric breakdown can begin,” said McLaren.
“Charlie’s work in Marburg has helped us see the kinetics of the process,” Jain said. “We could see it happening abruptly in our experiments here at Lehigh, but we now have a way to separate out what occurs specifically with the depletion layer.”
Learn more: NEW CURRENTS IN GLASS STUDIES
In July, videos of the fatal police shootings of Alton Sterling—a black man in Louisiana—and Philando Castile—a black man in Minnesota—went viral on social media. The immediate aftermath of the Castile shooting was first shared via Facebook Live, which is a type of mobile streaming video technology (MSVT) that allows users to stream live video to followers, similar to Periscope and Meerkat.
The real-time video of Castile’s death reached over 5 million people within a week of its posting.
In a new study, Up, Periscope: Mobile Streaming Video Technologies, Privacy in Public, and the Right to Record, Jeremy Littau, assistant professor of journalism at Lehigh University, and Daxton Stewart, associate dean and associate professor in the Bob Schieffer College of Communication at Texas Christian University, examine the legal rights of people to record and live-stream and any potential right to be free from being recorded and streamed in public places.
The authors find that current laws protecting individual rights are insufficient to protect privacy when it comes to these technologies and that the First Amendment likely protects livestreaming activities of users.
“The Castile shooting is important not only for its content, but also because a Facebook user showed the public a new tool that it might not otherwise have known about or thought to use in a situation like this,” Littau says.
“What happened in Minnesota is one of those incidents that serve as a harbinger for what is to come.”
Because of the ease with which users are able to share live video streams, MSVTs have great potential to catalyze new privacy laws and policies, as legislatures, courts, citizens, and tech companies consider the balance between peoples individual’s right to privacy and the public’s right to free expression.
Littau says that mobile streaming technologies will soon completely change how the public views privacy. He predicts some entities will seek to carve out special exemptions for themselves.
“Our work already mentions situations where municipalities have tried to pass laws stopping citizens from recording police activities in public. It’s completely unconstitutional, but that won’t stop people from trying,” he explains. “Exempting public officials and government workers from the laws that apply to everyone is not a new idea in the U.S. At some point a locality is going to try and make it a crime to live stream police actions on the street.”
Services like Facebook Live break down the previous lag between information collection and information distribution, making potential privacy violations instantaneous and unavoidable, according to the research, which was published in print in Journalism and Mass Communication Quarterly in June.
The researchers advocate that privacy challenges be addressed directly between by mobile streaming companies and their users via contracts. Attempts to strengthen privacy laws will likely be thwarted by First Amendment protections.
“Ultimately consumers of tools like Periscope and Facebook Live will shape the way they are used,” Dr. Stewart says.
“If the developers do not place restraints on use, and do not provide tools for the community of users to monitor content, then it’s likely we will continue to see them put to troubling uses such the teenager who live-streamed her suicide in France, or the young woman who live-streamed a friend being sexually assaulted earlier this year.”
Stewart says the biggest challenge that the courts will face when these cases arise will be trying to fit old ways of thinking about privacy and public spaces into new tools that weren’t even foreseeable when those approaches to privacy were developed. “In this study, we advocate for less legal restraint of recording and live-streaming public matters or government officials in public places, which clearly deserve First Amendment protection,” he says. “But we also call for wisdom by users and tech companies in controlling the spread of materials that may be more harmful to private individuals.”
Lehigh University is an American private research university located in Bethlehem, Pennsylvania.
It was established in 1865 by businessman Asa Packer and has grown to include studies in a wide variety of disciplines. Its undergraduate programs have been coeducational since the 1971–72 academic year. As of 2014, the university had 4,904 undergraduate students and 2,165 graduate students. Lehigh is considered one of the twenty-four Hidden Ivies in the Northeastern United States.
The university has over 680 faculty members; awards and honors recognizing Lehigh faculty and alumni include the Nobel Prize, Pulitzer Prize, Fulbright Fellowship, and membership in the American Academy of Arts & Sciences and the National Academy of Sciences.
The university has four colleges: the P.C. Rossin College of Engineering and Applied Science, the College of Arts and Sciences, the College of Business and Economics, and the College of Education. The College of Arts and Sciences is the largest college today, home to roughly 40% percent of the university’s students. The university offers a variety of degrees, including Bachelor of Arts, Bachelor of Science, Master of Arts, Master of Science, Master of Business Administration, Master of Engineering, Master of Education, and Doctor of Philosophy.
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An international group of researchers has synthesized an extremely rare mineral and used it as a catalyst precursor to improve two reactions that are of great importance to the chemical industry.
Using a technique called supercritical anti-solvent precipitation (SAS), the group produced large quantities of highly pure georgeite, a disordered copper-hydroxycarbonate that is found naturally only in Australia and in an old copper mine in Snowdonia, Wales.
The group tested georgeite’s catalytic activity against commercial catalysts that have been used for a half-century in the water-gas shift reaction, in which water reacts with carbon dioxide to produce hydrogen.
“We found that the georgeite was a superb catalyst for the water-gas shift reaction and had a much higher performance compared to the commercial catalyst currently used in industry,” said Graham Hutchings, director of the Cardiff Catalysis Institute at Cardiff University in Wales.
Hydrogen is an essential ingredient in the manufacture of methanol and ammonia, which form the basis of hundreds of chemicals, including fuels, plastics, paints, solvents and fertilizer.
The group also found that their synthesized georgeite material was highly effective in carrying out methanol synthesis, in which CO2 and hydrogen are combined to make methanol.
“Catalysts based on copper-zinc oxide minerals have been used for many decades to catalyze both of these reactions,” said Christopher J. Kiely, professor of materials science and chemical engineering at Lehigh. “Our georgeite-derived materials represent the first time something potentially better has come along.”
The group reported its findings this week in Nature magazine in an article titled “Stable amorphous georgeite as a precursor to a high-activity catalyst.” The article was authored by researchers from Cardiff, Lehigh, the UK Catalysis Hub, University College London, Diamond Light Source in the United Kingdom, the University of Liverpool, the Technical University of Denmark, and Johnson Matthey, a multinational chemicals and sustainable technologies company headquartered in Royston, UK.
A readily synthesized precursor
Georgeite belongs to a family of minerals called copper hydroxycarbonates that are widely used as catalyst precursors in the chemical industry. Scientists are familiar with other hydroxycarbonates, such as malachite, aurichalcite and rosasite, but know little about georgeite because of its extreme rarity, low purity, instability and highly disordered nature.
Chemists at the Cardiff Catalysis Institute synthesized georgeite using SAS, in which CO2 is subjected to conditions of heat and pressure that put it into a supercritical state where it displays the characteristics of both a liquid and a gas.
“Supercritical CO2 expands like a gas to fill up a volume while retaining the viscosity of a liquid,” said Kiely. “It’s an unusual state of matter and has the ability when bubbled through a solution to make solids precipitate out very quickly. Supercritical CO2 is also used for processes such as decaffeinating coffee.”
Chemists at the Cardiff Catalysis Institute synthesized georgeite by dissolving a copper-zinc-oxide precursor in an organic solvent and then passing supercritical CO2 through the solvent to rapidly precipitate out the georgeite.
“[We have shown] that stable georgeite can be readily synthesized using supercritical carbon dioxide as an anti-solvent in a precipitation process,” the researchers wrote in Nature. “The synthetic georgeite materials are precursors to highly active methanol synthesis and superior water gas shift catalysts as compared to those currently prepared from crystalline malachite.
“This new route to georgeite will open up new opportunities for the use of this important material in a number of applications.”
A crucial role for crystals
Researchers at Lehigh and the Technical University of Denmark used advanced electron microscopy techniques to structurally characterize the georgeite and determine why it produces such high performing catalysts.
“We looked at the georgeite with an aberration-corrected STEM [scanning transmission electron microscope],” said Kiely. “Georgeite had been thought to be completely amorphous, that is, more like glass than a crystalline mineral. We found that georgeite is in fact about 90 percent amorphous but has 2-nanometer crystals of copper oxide embedded within it.
“The actual catalyst is not a pure georgeite material,” said Kiely. “The georgeite, when deliberately doped with some zinc, is really a precursor to the active catalyst. It needs to be calcined, or heated in air, and then reduced in hydrogen gas before it can be used as a catalyst.”
To learn what happened during calcination and reduction, the group turned to colleagues at the Technical University of Denmark, which has an environmental transmission electron microscope (ETEM).
“The ETEM is a very specialized instrument,” said Kiely. “The beauty of it is that you can take a zincian georgeite precursor, heat it up in the microscope under a gaseous environment and then watch how it changes during the process. This allowed us to dynamically view the precursor material as it transformed into the active catalyst.
“What we saw with the ETEM is that when calcined zincian georgeite is reduced in hydrogen, it forms very tiny copper particles intimately supported on nanoscopic zinc oxide grains. This special nanostructure is responsible for the good catalytic properties.
“We compared this with the conventional catalyst materials derived from a crystalline malachite, and found that our zincian georgeite results in a much finer microstructure, with smaller copper and zinc oxide particles, which ultimately contributes to the superior catalytic performance.”
The synthetic zincian georgeite catalyst, said Kiely, has the additional advantage that its composition can be easily tuned, or altered, by adjusting the ratio of copper atoms to zinc atoms in the starting solution. It can also be made in large quantities.