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  • richardmitnick 3:26 pm on June 19, 2017 Permalink | Reply
    Tags: Energy from sunlight alone to turn salt water into fresh drinking water, Membrane distillation, , NEWT’s direct solar desalination technology, Rice U   

    From Rice: “Freshwater from salt water using only solar energy” 

    Rice U bloc

    Rice University

    June 19, 2017
    Jade Boyd

    Modular, off-grid desalination technology could supply families, towns

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    This scaled up test bed of NEWT’s direct solar desalination technology uses carbon black nanoparticles that convert as much as 80 percent of sunlight energy into heat. Results from an earlier prototype showed the technology could produce as much as six liters of freshwater per hour per square meter of solar membrane. (Photo by Jeff Fitlow/Rice University)

    A federally funded research effort to revolutionize water treatment has yielded an off-grid technology that uses energy from sunlight alone to turn salt water into fresh drinking water. The desalination system, which uses a combination of membrane distillation technology and light-harvesting nanophotonics, is the first major innovation from the Center for Nanotechnology Enabled Water Treatment (NEWT), a multi-institutional engineering research center based at Rice University.

    NEWT’s “nanophotonics-enabled solar membrane distillation” technology, or NESMD, combines tried-and-true water treatment methods with cutting-edge nanotechnology that converts sunlight to heat. The technology is described online this week in the Proceedings of the National Academy of Sciences.

    More than 18,000 desalination plants operate in 150 countries, but NEWT’s desalination technology is unlike any other used today.

    “Direct solar desalination could be a game changer for some of the estimated 1 billion people who lack access to clean drinking water,” said Rice scientist and water treatment expert Qilin Li, a corresponding author on the study. “This off-grid technology is capable of providing sufficient clean water for family use in a compact footprint, and it can be scaled up to provide water for larger communities.”

    2
    Rice University researchers (from left) Naomi Halas, Qilin Li, Peter Nordlander, Seth Pederson, Alessandro Alabastri and Pratiksha Dongare with a scaled up test bed of the NEWT Center’s direct solar desalination system. (Photo by Jeff Fitlow/Rice University)

    The oldest method for making freshwater from salt water is distillation. Salt water is boiled, and the steam is captured and run through a condensing coil. Distillation has been used for centuries, but it requires complex infrastructure and is energy inefficient due to the amount of heat required to boil water and produce steam. More than half the cost of operating a water distillation plant is for energy.

    An emerging technology for desalination is membrane distillation, where hot salt water is flowed across one side of a porous membrane and cold freshwater is flowed across the other. Water vapor is naturally drawn through the membrane from the hot to the cold side, and because the seawater need not be boiled, the energy requirements are less than they would be for traditional distillation. However, the energy costs are still significant because heat is continuously lost from the hot side of the membrane to the cold.

    “Unlike traditional membrane distillation, NESMD benefits from increasing efficiency with scale,” said Rice’s Naomi Halas, a corresponding author on the paper and the leader of NEWT’s nanophotonics research efforts. “It requires minimal pumping energy for optimal distillate conversion, and there are a number of ways we can further optimize the technology to make it more productive and efficient.”

    NEWT’s new technology builds upon research in Halas’ lab to create engineered nanoparticles that harvest as much as 80 percent of sunlight to generate steam. By adding low-cost, commercially available nanoparticles to a porous membrane, NEWT has essentially turned the membrane itself into a one-sided heating element that alone heats the water to drive membrane distillation.

    “The integration of photothermal heating capabilities within a water purification membrane for direct, solar-driven desalination opens new opportunities in water purification,” said Yale University ‘s Menachem “Meny” Elimelech, a co-author of the new study and NEWT’s lead researcher for membrane processes.

    3
    In conventional membrane distillation (top), hot saltwater is flowed across one side of a porous membrane and cold freshwater is flowed across the other. Water vapor is naturally drawn through the membrane from the hot to the cold side. In NEWT’s “nanotechnology-enabled solar membrane distillation,” or NESMD (bottom), a porous layer of sunlight-activated carbon black nanoparticles acts as the heating element for the process. (Image courtesy P. Dongare/Rice University)

    In the PNAS study, researchers offered proof-of-concept results based on tests with an NESMD chamber about the size of three postage stamps and just a few millimeters thick. The distillation membrane in the chamber contained a specially designed top layer of carbon black nanoparticles infused into a porous polymer. The light-capturing nanoparticles heated the entire surface of the membrane when exposed to sunlight. A thin half-millimeter-thick layer of salt water flowed atop the carbon-black layer, and a cool freshwater stream flowed below.

    Li, the leader of NEWT’s advanced treatment test beds at Rice, said the water production rate increased greatly by concentrating the sunlight. “The intensity got up 17.5 kilowatts per meter squared when a lens was used to concentrate sunlight by 25 times, and the water production increased to about 6 liters per meter squared per hour.”

    Li said NEWT’s research team has already made a much larger system that contains a panel that is about 70 centimeters by 25 centimeters. Ultimately, she said, NEWT hopes to produce a modular system where users could order as many panels as they needed based on their daily water demands.

    “You could assemble these together, just as you would the panels in a solar farm,” she said. “Depending on the water production rate you need, you could calculate how much membrane area you would need. For example, if you need 20 liters per hour, and the panels produce 6 liters per hour per square meter, you would order a little over 3 square meters of panels.”

    Established by the National Science Foundation in 2015, NEWT aims to develop compact, mobile, off-grid water-treatment systems that can provide clean water to millions of people who lack it and make U.S. energy production more sustainable and cost-effective. NEWT, which is expected to leverage more than $40 million in federal and industrial support over the next decade, is the first NSF Engineering Research Center (ERC) in Houston and only the third in Texas since NSF began the ERC program in 1985. NEWT focuses on applications for humanitarian emergency response, rural water systems and wastewater treatment and reuse at remote sites, including both onshore and offshore drilling platforms for oil and gas exploration.

    Li is Rice’s professor of civil and environmental engineering, chemical and biomolecular engineering, and materials science and nanoengineering. Halas is Rice’s Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering. Elimelech is Yale’s Roberto C. Goizueta Professor of Environmental and Chemical Engineering.

    Additional study co-authors include Pratiksha Dongare, Alessandro Alabastri, Seth Pedersen, Katherine Zodrow, Nathaniel Hogan, Oara Neumann, Jinjian Wu, Tianxiao Wang and Peter Nordlander, all of Rice, and Akshay Deshmukh of Yale University.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

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  • richardmitnick 5:31 pm on June 8, 2017 Permalink | Reply
    Tags: EureKAlert, Rice U, Seismic CT scan points to rapid uplift of Southern Tibet,   

    From TACC and Rice via EurekAlert: Seismic CT scan points to rapid uplift of Southern Tibet 

    TACC bloc

    Texas Advanced Computing Center

    Rice U bloc

    Rice University

    1

    AAAS EurekAlert

    3
    The Tibetan Plateau as seen from Space Shuttle Challenger in October 1984. Credit NASA

    Using seismic data and supercomputers, Rice University geophysicists have conducted a massive seismic CT scan of the upper mantle beneath the Tibetan Plateau and concluded that the southern half of the “Roof of the World” formed in less than one-quarter of the time since the beginning of India-Eurasia continental collision.

    The research, which appears online this week in the journal Nature Communications, finds that the high-elevation of Southern Tibet was largely achieved within 10 million years. Continental India’s tectonic collision with Asia began about 45 million years ago.

    “The features that we see in our tomographic image are very different from what has been seen before using traditional seismic inversion techniques,” said Min Chen, the Rice research scientist who headed the project. “Because we used full waveform inversion to assimilate a large seismic data set, we were able to see more clearly how the upper-mantle lithosphere beneath Southern Tibet differs from that of the surrounding region. Our seismic image suggests that the Tibetan lithosphere thickened and formed a denser root that broke away and sank deeper into the mantle. We conclude that most of the uplift across Southern Tibet likely occurred when this lithospheric root broke away.”

    The research could help answer longstanding questions about Tibet’s formation. Known as the “Roof of the World,” the Tibetan Plateau stands more than three miles above sea level. The basic story behind its creation — the tectonic collision between the Indian and Eurasian continents — is well-known to schoolchildren the world over, but the specific details have remained elusive. For example, what causes the plateau to rise and how does its high elevation impact Earth’s climate?

    “The leading theory holds that the plateau rose continuously once the India-Eurasia continental collision began, and that the plateau is maintained by the northward motion of the Indian plate, which forces the plateau to shorten horizontally and move upward simultaneously,” said study co-author Fenglin Niu, a professor of Earth science at Rice. “Our findings support a different scenario, a more rapid and pulsed uplift of Southern Tibet.”

    It took three years for Chen and colleagues to complete their tomographic model of the crust and upper-mantle structure beneath Tibet. The model is based on readings from thousands of seismic stations in China, Japan and other countries in East Asia. Seismometers record the arrival time and amplitude of seismic waves, pulses of energy that are released by earthquakes and that travel through Earth. The arrival time of a seismic wave at a particular seismometer depends upon what type of rock it has passed through. Working backward from instrument readings to calculate the factors that produced them is something scientists refer to as an inverse problem, and seismological inverse problems with full waveforms incorporating all kinds of usable seismic waves are some of the most complex inverse problems to solve.

    Chen and colleagues used a technique called full waveform inversion, “an iterative full waveform-matching technique that uses a complicated numerical code that requires parallel computing on supercomputers,” she said.

    “The technique really allows us to use all the wiggles on a large number of seismographs to build up a more realistic 3-D model of Earth’s interior, in much the same way that whales or bats use echo-location,” she said. “The seismic stations are like the ears of the animal, but the echo that they are hearing is a seismic wave that has either been transmitted through or bounced off of subsurface features inside Earth.”

    The tomographic model includes features to a depth of about 500 miles below Tibet and the Himalaya Mountains. The model was computed on Rice’s DAVinCI computing cluster and on supercomputers at the University of Texas that are part of the National Science Foundation’s Extreme Science and Engineering Discovery Environment (XSEDE).

    Some of the TACC systems:

    Dell Poweredge U Texas Austin Stampede Supercomputer. Texas Advanced Computer Center 9.6 PF

    TACC Lonestar Cray XC40 supercomputer

    TACC Maverick HP NVIDIA supercomputer

    TACC Wrangler Dell Inc. EMC supercomputer

    Rice’s IBM iDataPlex DAVinCI computing cluster

    “The mechanism that led to the rise of Southern Tibet is called lithospheric thickening and foundering,” Chen said. “This happened because of convergence of two continental plates, which are each buoyant and not easy to subduct underneath the other plate. One of the plates, in this case on the Tibetan side, was more deformable than the other, and it began to deform around 45 million years ago when the collision began. The crust and the rigid lid of upper mantle — the lithosphere — deformed and thickened, and the denser lower part of this thickened lithosphere eventually foundered, or broke off from the rest of the lithosphere. Today, in our model, we can see a T-shaped section of this foundered lithosphere that extends from a depth of about 250 kilometers to at least 660 kilometers.”

    Chen said that after the denser lithospheric root broke away, the remaining lithosphere under Southern Tibet experienced rapid uplift in response.

    “The T-shaped piece of foundered lithosphere sank deeper into the mantle and also induced hot upwelling of the asthenosphere, which leads to surface magmatism in Southern Tibet,” she said.

    Such magmatism is documented in the rock record of the region, beginning around 30 million years ago in an epoch known as the Oligocene.

    “The spatial correlation between our tomographic model and Oligocene magmatism suggests that the Southern Tibetan uplift happened in a relatively short geological span that could have been as short as 5 million years,” Chen said.

    Additional co-authors include Adrian Lenardic, Cin-Ty Lee, Wenrong Cao and Julia Ribeiro, all of Rice, and Jeroen Tromp of Princeton University.

    The research was supported by a grant from the National Science Foundation (NSF), by the NSF’s Extreme Science and Engineering Discovery Environment (XSEDE) program, and by the China Earthquake Administration’s China Seismic Array Data Management Center. Rice’s DAVinCI supercomputer is administered by Rice’s Center for Research Computing and procured in partnership with the Ken Kennedy Institute for Information Technology.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

    The Texas Advanced Computing Center (TACC) designs and operates some of the world’s most powerful computing resources. The center’s mission is to enable discoveries that advance science and society through the application of advanced computing technologies.

     
  • richardmitnick 2:47 pm on June 6, 2017 Permalink | Reply
    Tags: , , Rice U, Texas team debuts battery-less pacemaker   

    From Rice: “Texas team debuts battery-less pacemaker” 

    Rice U bloc

    Rice University

    June 5, 2017
    Mike Williams

    1
    The internal components of a battery-free pacemaker introduced this week by Rice University and the Texas Heart Institute. The pacemaker can be inserted into the heart and powered by a battery pack outside the body, eliminating the need for wire leads and surgeries to occasionally replace the battery. Courtesy of Rice Integrated Systems and Circuits.

    A wireless, battery-less pacemaker that can be implanted directly into a patient’s heart is being introduced by researchers from Rice University and their colleagues at the Texas Heart Institute (THI) at the IEEE’s International Microwave Symposium (IMS) in Honolulu June 4-9.

    The pacemaker designed by the Rice lab of electrical and computer engineering professor Aydin Babakhani harvests energy wirelessly from radio frequency radiation transmitted by an external battery pack. In the prototype presented at IMS, the wireless power transmitter can be up to few centimeters away.

    Pacemakers use electrical signals to prompt the heart to keep a steady beat, but they’ve traditionally not been implanted directly into a patient’s heart. Instead, they’re located away from the heart, where surgeons can periodically replace their onboard batteries with minor surgery; their electrical signals are transmitted to the heart via wires called “leads.”

    Some of the common problems with this arrangement are complications related to the leads, including bleeding and infection. Babakhani said Rice’s prototype wireless pacemaker reduces these risks by doing away with leads.

    He said other recently introduced lead-less pacemakers also mitigate some of these complications, but their form factors limit them to a single heart chamber and they are unable to provide dual-chamber or biventricular pacing. In contrast, battery-less, lead-less and wirelessly powered microchips can be implanted directly to pace multiple points inside or outside the heart, Babakhani said.

    “This technology brings into sharp focus the remarkable possibility of achieving the ‘Triple Crown’ of treatment of both the most common and most lethal cardiac arrhythmias: external powering, wireless pacing and — far and away most importantly — cardiac defibrillation that is not only painless but is actually imperceptible to the patient,” said Dr. Mehdi Razavi, director of clinical arrhythmia research and innovation at THI and an associate professor at Baylor College of Medicine, who collaborated with Babakhani on development and testing of the new pacemaker.

    The chip at the system’s heart is less than 4 millimeters wide and incorporates the receiving antenna, an AC-to-DC rectifier, a power management unit and a pacing activation signal. A capacitor and switch join the chip on a circuit board that is smaller than a dime. The chip receives power using microwaves microwaves in the 8 to 10 gigahertz electromagnetic frequency spectrum.

    The frequency of the pacing signals produced by the pacemaker can be adjusted by increasing or decreasing power transmitted to the receiving antenna, which stores it until it reaches a predetermined threshold. At that point, it releases the electrical charge to the heart and begins to fill again.

    The team successfully tested the device in a pig and demonstrated it could tune the animal’s heart rate from 100 to 172 beats per minute.

    A short paper describing the device will be released at the conference. The paper’s authors are Babakhani and Yuxiang Sun of Rice; Brian Greet, David Burkland and Razavi of Baylor College of Medicine and THI; and Mathews John of THI.

    Babakhani said the invention has prompted new collaborations among the Texas Medical Center institutions as well as the University of California at San Diego. The team is further developing its technology in collaboration with Farshad Raissi, a cardiac electrophysiologist and assistant professor of medicine at UCSD, Rice’s Behnaam Aazhang, the J.S. Abercrombie Professor of Electrical and Computer Engineering, and Rice’s Joseph Cavallaro, professor of electrical and computer engineering and of computer science.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 11:49 am on May 31, 2017 Permalink | Reply
    Tags: , but tender, cancer fighters, Epothilones, , Rice lab creates tough, Rice U   

    From RICE: “Rice lab creates tough, but tender, cancer fighters” 

    Rice U bloc

    Rice University

    May 30, 2017
    Mike Williams

    Variations of anti-tumor agents prove effective in the lab against even drug-resistant cancers

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    This is the structure of one of the analogs of epothilone B, a new compound created in the Rice University lab of synthetic organic chemist K.C. Nicolaou that shows promise as a cancer fighter. Courtesy of the Nicolaou Group.

    Rice University scientists have developed and evaluated analogs of potent anti-tumor agents known as epothilones using designs and methods that both improve their biological properties and simplify their manufacture.

    The substances introduced by Rice synthetic organic chemist K.C. Nicolaou are similar in their cancer-fighting mechanism to paclitaxel, the drug for which he is best-known, but have superior properties. Some compounds of the dozens of variations the scientists created exhibit potent cytotoxicities against certain cancer cells, including a drug-resistant cell line, Nicolaou said.

    The new research study is described this month in the Journal of the American Chemical Society.

    Like the family of taxanes (of which paclitaxel is a member), epothilones prevent cancer cells from dividing by interfering with tubulin proteins that form the cells’ skeletal microtubules. Tests with kidney cancer and two human uterine sarcoma cell lines, one with multidrug resistance, showed that 10 of these new compounds were impressively potent against all three cell lines, the researchers reported.

    “This is another example of a larger theme in our research, that of the synthesis of complex, rare natural products and their analogs for biological investigations,” Nicolaou said. “Our work is directed toward drug discovery and development in collaboration with biotechnology and pharmaceutical companies, particularly in the cancer area.”

    The drugs are variations of epothilone B, a natural product isolated from Sorangium cellulosum, slime bacteria that live in soil. Nicolaou and his colleagues achieved the total synthesis of several of the natural products and related substances in the past, but those compounds proved too toxic to be used as anti-cancer drugs, he said.

    “These new results are significant because they represent the discovery of a number of more potent variations of the natural product as cytotoxic agents against cancer cells,” Nicolaou said. “This brings these members of the epothilone class within range of suitability as payloads for antibody-drug conjugates, a new paradigm for targeted cancer therapy.”

    2
    This is the general structure of the newly synthesized aziridine epothilone B analogs developed at Rice University. The red-colored structural motifs designate the novel functionalities introduced into the epothilone B molecule that led to their enhanced properties as cancer-fighting agents. Courtesy of the Nicolaou Group.

    Just as important, he said, is the lab’s ability to add chemical “handles” to the molecules that allow them to be attached to drug-delivery systems like cancer-specific antibodies.

    Nicolaou compared the reconfiguration of epothilone B, the starting material for their synthesis, with the transplant of body parts, as he and his team replaced components in the molecule to make the designed analogs more effective.

    “The strategy we developed to synthesize them can be described as a kind of chemical surgery,” he said. “The most important structural motif we introduced in these new molecules is the three-membered ring containing a nitrogen atom, a so-called aziridine moiety.” The importance of the aziridine ring is not yet clear, he said, but it could serve as a handle to attach the molecule onto an antibody through a linker.

    “The other structural motif, the so-called side chain with a basic nitrogen embedded at a strategic position, was achieved through new extensions and improvements developed in our laboratories of the previously known HWE (Horner–Wadsworth–Emmons) reaction,” Nicolaou said. “The HWE reaction is an important process for making olefinic bonds (carbon-carbon double bonds) stereoselectively.”

    He said the new line of research was made possible by the work of Rice colleague László Kürti, who with his team developed a “powerful reaction” that offered a simple, scalable and fast method to synthesize aziridine rings from olefins. That research led by Kürti, then of the University of Texas Southwestern Medical Center, John Falck of Southwestern and Daniel Ess of Brigham Young University was reported in Science in 2014.

    Lead authors of the paper are Rice postdoctoral researchers Derek Rhoades and Yanping Wang. Co-authors are scientists Ruoli Bai and Ernest Hamel of the National Cancer Institute and scientist Monette Aujay, research associate Joseph Sandoval and principal scientist Julia Gavrilyuk of AbbVie Stemcentrx, San Francisco.

    The National Institutes of Health, the Cancer Prevention and Research Institute of Texas and the Welch Foundation supported the research.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 10:31 am on May 13, 2017 Permalink | Reply
    Tags: , Karlsruhe Institute of Technology, , Rice U   

    From Rice: “Entropy landscape sheds light on quantum mystery” 

    Rice U bloc

    Rice University

    May 12, 2017
    Jade Boyd

    Rice, Karlsruhe physicists probe entropy near quantum phase transition

    By precisely measuring the entropy of a cerium copper gold alloy with baffling electronic properties cooled to nearly absolute zero, physicists in Germany and the United States have gleaned new evidence about the possible causes of high-temperature superconductivity and similar phenomena.

    “This demonstration provides a foundation to better understand how novel behaviors like high-temperature superconductivity are brought about when certain kinds of materials are cooled to a quantum critical point,” said Rice University physicist Qimiao Si, co-author of a new study about the research in this week’s Nature Physics.

    The experimental research was led by Hilbert von Löhneysen of the Karlsruhe Institute of Technology in Karlsruhe, Germany. Löhneysen’s team, including study lead author Kai Grube, spent a year conducting dozens of experiments on a compound made of cerium copper and gold. By studying the effect of stress, or pressure applied in specific directions, and by making the materials very cold, the team subtly changed the spacing between the atoms in the crystalline metallic compounds and thus altered their electronic properties.

    The cerium copper gold alloys are “heavy fermions,” one of several of types of quantum materials that exhibit exotic electronic properties when very cold. The best-known of these are high-temperature superconductors, so named for their ability to conduct electrical current with zero resistance at temperatures well above those of traditional superconductors. Heavy fermions exhibit a different oddity: Their electrons appear to be effectively hundreds of times more massive than normal and, equally unusual, the effective electron mass seems to vary strongly as temperature changes.

    These odd behaviors defy traditional physical theories. They also occur at very cold temperatures and come about when the materials are tuned to a “quantum phase transition” — a change from one state to another, like ice melting. In 2001, Si and colleagues offered a new theory: At the quantum critical point, electrons fluctuate between two entirely different quantum states, so much so that their effective mass becomes infinitely large. The theory predicted certain tell-tale signs as the quantum critical point is approached, and Si has worked with experimental physicists for the past 16 years to amass evidence to support the theory.

    “Liquid water and ice are two of the classical states in which H2O can exist,” said Si, director of the Rice Center for Quantum Materials. “Ice is a very ordered phase because the H2O molecules are neatly arranged in a crystal lattice. Water is less ordered compared with ice, but flowing water molecules still have underlying order. The critical point is where things are fluctuating between these two types of order. It’s the point where H2O molecules sort of want to go to the pattern according to ice and sort of want to go to the pattern according to water.

    “It’s very similar in a quantum phase transition,” he said. “Even though this transition is driven by quantum mechanics, it is still a critical point where there’s maximum fluctuation between two ordered states. In this case, the fluctuations are related to the ordering of the ‘spins’ of electrons in the material.”

    Spin is an inherent property — like eye color — and every electron’s spin is classified as being either “up” or “down.” In magnets, like iron, spins are aligned in the same direction. But many materials exhibit the opposite behavior: Their spins alternate in a repeating up, down, up, down pattern that physicists refer to as “antiferromagnetic.”

    Hundreds of experiments on heavy fermions, high-temperature superconductors and other quantum materials have found that magnetic order differs on either side of a quantum critical point. Typically, experiments find antiferromagnetic order in one range of chemical composition, and a new state of order on the other side of the critical point.

    “A reasonable picture is that you can have an antiferromagnetic order of spins, where the spins are quite ordered, and you can have another state in which the spins are less ordered,” said Si, Rice’s Harry C. and Olga K. Wiess Professor of Physics and Astronomy. “The critical point is where fluctuations between these two states are at their maximum.”

    The cerium copper gold compound has become a prototype heavy fermion material for quantum criticality, largely due to the work of von Löhneysen’s group.

    “In 2000, we did inelastic neutron scattering experiments in the quantum critical cerium copper gold system,” said von Löhneysen. “We found a spatial-temporal profile so unusual that it could not be understood in terms of the standard theory of metal.”

    Si said that study was one of the important factors that stimulated him and his co-authors to offer their 2001 theory, which helped explain von Löhneysen’s puzzling results. In subsequent studies, Si and colleagues also predicted that entropy — a classical thermodynamic property — would increase as quantum fluctuations increased near a quantum critical point. The well-documented properties of cerium copper gold provided a unique opportunity to test the theory, Si said.

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    Physicists at Karlsruhe Institute of Technology used this capacitive dilatometer to measure the thermal expansion in cerium copper gold alloys cooled to temperatures very close to absolute zero with a precision of one tenth of a trillionth of a meter, or approximately one-thousandth the radius of single atom. The precise thermal expansion measurements allowed the researchers to map out the stress dependence of entropy in materials as they were cooled to the point of a quantum phase transition. (Image courtesy of K. Grube/Karlsruhe Institute of Technology)

    In cerium copper-six, substituting small amounts of gold for copper allows researchers to slightly increase the spacing between atoms. In the critical composition, the alloys undergo an antiferromagnetic quantum phase transition. By studying this composition and measuring the entropy numerous times under varying conditions of stress, the Karlsruhe team was able to create a 3-D map that showed how entropy at very low yet finite temperature steadily increased as the system approached the quantum critical point.

    No direct measure of entropy exists, but the ratio of entropy changes to stress is directly proportional to another ratio that can be measured: the amount the sample expands or contracts due to changes in temperature. To enable the measurements at the extraordinarily low temperatures required, the Karlsruhe team developed a method for accurately measuring length changes of less than one tenth of a trillionth of a meter — approximately one-thousandth the radius of a single atom.

    “We measured the entropy as a function of stress applied along all the different principal directions,” said Grube, a senior researcher at Karlsruhe Institute of Technology. “We made a detailed map of the entropy landscape in the multidimensional parameter space and verified that the quantum critical point sits on top of the entropy mountain.”

    Von Löhneysen said the thermodynamic measurements also provide new insights into the quantum fluctuations near the critical point.

    “Surprisingly, this methodology allows us to reconstruct the underlying spatial profile of quantum critical fluctuations in this quantum critical material,” he said. “This is the first time that this kind of methodology has been applied.”

    Si said it came as a surprise that this could be done using nothing more than entropy measurements.

    “It is quite remarkable that the entropy landscape can connect so well with the detailed profile of the quantum critical fluctuations determined from microscopic experiments such as inelastic neutron scattering, all the more so when both end up providing direct evidence to support the theory,” he said.

    More generally, the demonstration of the pronounced entropy enhancement at a quantum critical point in a multidimensional parameter space raises new insights into the way electron-electron interactions give rise to high-temperature superconductivity, Si said.

    “One way to relieve the accumulated entropy of a quantum critical point is for the electrons in the system to reorganize themselves into novel phases,” he said. “Among the possible phases that ensue is unconventional superconductivity, in which the electrons pair up and form a coherent macroscopic quantum state.”

    Additional co-authors include Sebastian Zaum of Karlsruhe and Oliver Stockert of the Max-Planck Institute for Chemical Physics of Solids in Dresden, Germany. The research was supported by the German Science Foundation, the National Science Foundation, the Humboldt Foundation, the Army Research Office, the Welch Foundation and the Rice Center for Quantum Materials.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 12:09 pm on April 13, 2017 Permalink | Reply
    Tags: , , Rice U   

    From Rice: “Proton-nuclei smashups yield clues about ‘quark gluon plasma’ “ 

    Rice U bloc

    Rice University

    April 10, 2017
    Jade Boyd

    Rice University physicists probe exotic state of nuclear matter at Europe’s LHC

    1
    A visual of data collected by the Compact Muon Solenoid detector during a proton-lead collision at the Large Hadron Collider in 2016. (Image courtesy of Thomas McCauley/CERN)

    Findings from Rice University physicists working at Europe’s Large Hadron Collider (LHC) are providing new insight about an exotic state of matter called the “quark-gluon plasma” that occurs when protons and neutrons melt.

    As the most powerful particle accelerator on Earth, the LHC is able to smash together the nuclei of atoms at nearly the speed of the light. The energy released in these collisions is vast and allows physicists to recreate the hot, dense conditions that existed in the early universe. Quark-gluon plasma, or QGP, is a high-energy soup of particles that’s formed when protons and neutrons melt at temperatures approaching several trillion kelvins.

    In a recent paper in Physical Review Letters written on behalf of more than 2,000 scientists working on the LHC’s Compact Muon Solenoid (CMS) experiment, Rice physicists Wei Li and Zhoudunming (Kong) Tu proposed a new approach for studying a characteristic magnetic property of QGP called the “chiral magnetic effect” (CME).

    CERN/CMS Detector

    Their approach uses collisions between protons and lead nuclei. CME is an electromagnetic phenomenon that arises as a consequence of quantum mechanics and is also related to so-called topological phases of matter, an area of condensed matter physics that has drawn increased worldwide attention since capturing the Nobel Prize in physics in 2016.

    “To find evidence for the chiral magnetic effect and thus topological phases in hot QGP matter has been a major goal in the field of high-energy nuclear physics for some time,” Li said. “Early findings, although indicative of the CME, still remain inconclusive, mainly because of other background processes that are difficult to control and quantify.”

    QGP was first produced around 2000 at the Relativistic Heavy Ion Collider in New York and later at the LHC in 2010.

    BNL/RHIC

    CERN/LHC Map

    In those experiments, physicists smashed together two fast-moving lead nuclei, each of containing 82 protons and 126 neutrons, the two building blocks of all atomic nuclei. Because the melting protons in these collisions each carries a positive electric charge, the QGPs from these experiments contained enormously strong magnetic fields, which are estimated to be about a trillion times stronger than the strongest magnetic field ever created in a laboratory.

    The chiral magnetic effect is an exotic asymmetric electromagnetic effect that only arises due to the combination of quantum mechanics and the extreme physical conditions in a QGP. The laws of classical electrodynamics would forbid the existence of such a state, and indeed, Li’s inspiration for the new experiments arose from thinking about the problem in classical terms.

    “I was inspired by a problem in an undergraduate course I was teaching on classical electrodynamics,” Li said.

    Two years ago Li discovered that head-on collisions at LHC between a lead nucleus and a single proton created small amounts of particles that appeared to behave as a liquid. On closer analysis, he and colleagues at CMS found the collisions were creating small amounts of QGP.

    In a 2015 Rice News report about the discovery, Rice alumnus Don Lincoln, a particle physicist and physics communicator at Fermilab, wrote, “This result was surprising because when the proton hits the lead nucleus, it punches a hole through much of the nucleus, like shooting a rifle at a watermelon (as opposed to colliding two lead nuclei, which is like slamming two watermelons together).”

    Li said, “One unusual thing about the droplets of QGP created in proton-lead collisions is the configuration of their magnetic fields. The QGP is formed near the center of the initial lead nucleus, which makes it easy to tell that the strength of the magnetic field is rather negligible in comparison with the QGP created in lead-lead collisions. As a result, proton-lead collisions provide us a means to switch off the magnetic field — and the CME signal — in a QGP in a well-controlled way.”

    In the new paper, Li, Tu and their CMS colleagues showed evidence from proton-lead collision data that helps shed light on the electromagnetic behaviors that arise from the chiral magnetic effect in lead-lead QGPs.

    Li said more details still need to be worked out before a definitive conclusion can be drawn, but he said the results bode well for future QGP discoveries at the LHC.

    “This is just a first step in a new avenue opened up by proton-nucleus collisions for the search of exotic topological phases in QGP,” Li said. “We are working hard on accumulating more data and performing a series of new studies. Hopefully, in coming years, we will see the first direct evidence for the chiral magnetic effect.”

    The research is supported by the Department of Energy, the Robert Welch Foundation and Alfred Sloan Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 9:33 pm on December 14, 2016 Permalink | Reply
    Tags: , Light provides pull for future nanocatalyst measurement, , Rice U   

    From Rice: “Light provides pull for future nanocatalyst measurement” 

    Rice U bloc

    Rice University

    December 14, 2016
    David Ruth
    713-348-6327
    david@rice.edu

    Jade Boyd
    713-348-6778
    jadeboyd@rice.edu

    Rice University photonics lab tests photon-induced force microscopy

    1
    An illustration (left) depicts the technique known as “photo-induced force microscopy,” and the images at right show how closely the experimental and theoretical findings match in a recent investigation of the technique at Rice University. Illustration by Chloe Doiron/Rice University. Reprinted with permission from Nano Letters 2016, Articles ASAP, DOI: 10.1021/acs.nanolett.6b04245. Copyright 2016 American Chemical Society.

    Rice University nanophotonics researcher Isabell Thomann uses lasers, light-activated materials and light-measuring nanoscale tips to push the boundaries of experimental nanoscience, but light is providing the pull in her latest study.

    In a new paper in the American Chemical Society journal Nano Letters [link is in image caption], Thomann and colleagues, including postdoctoral fellow Thejaswi Tumkur and graduate student Xiao Yang, combine experiment and theory to test a new technique called “photo-induced force microscopy,” which probes the optical properties of nanomaterials by measuring the physical force imparted by light.

    Thomann’s primary research centers on using nanoparticles and sunlight to reduce the carbon footprint of power plants. The work crosses boundaries of chemistry, optics, electrical engineering, energy and the environment, but a major focus is photocatalysis, a class of processes in which light interacts with high-tech materials to drive chemical reactions.

    “Many experiments nowadays are done under high vacuum, but I want to run the reactor in my lab under more realistic conditions — normal temperature, normal pressure, in the presence of water — that will apply to capturing sunlight for photocatalysis,” said Thomann, an assistant professor of electrical and computer engineering, of materials science and nanoengineering and of chemistry at Rice

    Thomann has been working to develop new tools for measuring nanomaterials since arriving at Rice in 2012. She and her team are developing an ultrafast laser spectroscopy system that can read the optical signatures of short-lived chemical processes that are relevant to artificial photosynthesis.

    “In a chemical reaction, there are reactants, which are the chemical inputs, and there are products, which are the outputs,” Thomann said. “Almost all reactions driven by light involve multiple steps where light is converted to quantum particulates such as electrons or phonons that need to be transported to surfaces to drive chemical reactions. It is very helpful to know exactly what these are, when they are made and in what quantity, particularly if you are optimizing a process for industrial use.”

    Thomann’s group designs light-activated nanoparticles that can capture energy from sunlight and use it to initiate chemical reactions. The nanocatalysts, which can be tiny rods or discs of metal or other materials, interact with light due in part to their shapes and how closely they are spaced together. Thomann said that while engineers make every effort to produce uniform particles, small imperfections still exist and can have significant consequences on performance.

    3
    These images show the measured optical forces for an array of plasmonic gold disc pairs known as dimers that were probed by an atomic force microscopy tip. The map reveals slight differences caused by minute imperfections in the dimers. Image courtesy of the Thomann Group/Rice University. Reprinted with permission from Nano Letters 2016, Articles ASAP, DOI: 10.1021/acs.nanolett.6b04245. Copyright 2016 American Chemical Society.

    “Photocatalysts are often heterogeneous, which means they are not all exactly alike, and we need better tools for examining them with high spatial resolution in order to see these small differences,” she said. “We also need to follow the reaction processes with high temporal resolution, and we want to do all of this with much better spatial resolution than can be achieved with a normal optical microscope.”

    In the photon-induced force microscopy experiments, Thomann’s team used a tiny tip from an atomic force microscope (AFM) to enhance the spatial resolution of measurements taken from gold nanorods and nanodiscs on glass surfaces. The rods and discs, which are smaller than the wavelength of light used to measure them, would normally be blurry in an optical microscope due to a physical property called the diffraction limit. To better resolve the nanoparticles, and the electromagnetic interactions between them, Thomann’s group shines light at the particles and uses an AFM tip to probe how these nanoparticles act as optical nanoantennas and concentrate the light.

    “If we were trying to measure the reflected light, it would be very difficult because there are only a few scattered photons against a very busy background where light is bouncing all over the place, especially if these measurements were carried out in a liquid environment,” Thomann said. “But we are instead measuring the force exerted on the AFM tip, the slight pull on the tip when the optical nanoantennas are illuminated by light. It turns out that measuring the force is a much more sensitive technique than trying to collect the few photons scattered off the tip.”

    Thomann said the study provides theoretical understanding of how photo-induced force microscopy works and lays the groundwork for future studies of more complex photocatalyst materials her team hopes to create in the future. She credited her group’s improved understanding of the force-measuring technique to months of hard work by co-author Xiao Yang, a Rice graduate student in the group of theoretical physicist and study co-author Peter Nordlander.

    Yang said the most difficult part of coming up with an explanation of the team’s experimental results was creating a solvable computational model that accurately described the real-world physics. For example, including the entire tip in the model made the mathematics impractical.

    “I did try, at first, but it turned out it was impossible,” Yang said. “It would have taken an infinite time to reach convergence of the simulations.”

    Yang eventually hit upon an idea — including just a portion of the tip in the model — that made the calculations both feasible and accurate. Thomann said this was just one example of Yang’s tenacity in finding a workable solution.

    “He is exactly the kind of graduate student we want: knowledgeable, hard-working and unwilling to quit in the face of adversity,” she said.

    Tumkur is a member of the Thomann research group and a J. Evans Attwell-Welch Postdoctoral Fellow at Rice’s Smalley-Curl Institute. Additional co-authors include Benjamin Cerjan and Smalley-Curl Institute Director Naomi Halas, Rice’s Stanley C. Moore Professor of Electrical and Computer Engineering, professor of chemistry, of bioengineering, of physics and astronomy, and of materials science and nanoengineering. The research was supported by the Welch Foundation, the National Science Foundation and the Smalley-Curl Institute’s J. Evans Attwell-Welch Postdoctoral Fellowship Program.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 7:59 pm on September 12, 2016 Permalink | Reply
    Tags: , , Rice U   

    From Rice: “New tools join breast cancer fight” 

    Rice U bloc

    Rice University

    Sept. 12, 2016
    Jeff Falk
    713-348-6775
    jfalk@rice.edu

    Mike Williams
    713-348-6728
    mikewilliams@rice.edu

    International team finds existing drug may halt tumor growth, points way toward more effective treatments

    An international team including Rice University researchers has discovered a way to fight the overexpression of a protein associated with the proliferation of breast cancer.

    Dialing down the level of the protein NAF-1 and the activity of the iron-sulfur clusters it transports may be key to halting tumor growth, they reported.

    In a study this week in the Proceedings of the National Academy of Sciences, the researchers suggest a drug that is typically used to treat type 2 diabetes, pioglitazone, has proven effective at controlling NAF-1 levels.

    They also discovered that a single mutation to NAF-1 almost completely blocked the ability of cancer cells to proliferate, a result they said supports the idea that lowering NAF-1 expression can help stop tumors.

    Fine-tuning the drug to specifically address tumors could bring a new weapon to the battle against breast cancer and other cancers, the researchers said. Overexpression of NAF-1 also has been associated with prostate, gastric, cervical, liver and laryngeal cancer, they said.

    José Onuchic, Rice’s Harry C. and Olga K. Wiess Chair of Physics and professor of physics and astronomy and co-director of the Center for Theoretical Biological Physics (CTBP), worked with Rice research scientist Mingyang Lu, Rice postdoc Fang Bai and scientists from Israel, the University of California, San Diego (UCSD) and the University of North Texas on a multifaceted approach to define the role of NAF-1 in breast cancers.

    Understanding the mechanism will help the Rice researchers improve computer simulations to aid in the rapid design and testing of novel drugs, Onuchic said.

    NAF-1 is a member of the NEET family of proteins; these proteins transport clusters of iron and sulfur molecules inside cells. The clusters help regulate processes in cells by controlling reduction-oxidation (redox) and metabolic activity. They naturally adhere to the outer surface of the mitochondria, the “power plant” that supplies cells with chemical energy.

    Experiments demonstrated that the overexpression of NAF-1 in breast cancer tumors enhanced cancer cells’ ability to tolerate oxidative stress. That enhancement allowed the tumors to become much larger and more aggressive, said Ron Mittler, a professor of biological sciences at the University of North Texas.

    “Now that we know tumors that overexpress this protein are more sensitive to this type of drug, we can design new drugs in a way that will attack the clusters,” Mittler said.

    NAF-1 “is kind of like a seesaw,” said Patricia Jennings, a CTBP affiliate and a professor of chemistry and biochemistry at UCSD. “It’s a sensor that tells your cells when they’re getting out of balance and works very hard to bring them back. But once they get a little too far out of balance, the cells can die.”

    Treating the tumors with pioglitazone stabilized the iron-sulfur clusters in NAF-1, reducing the tumors’ tolerance to oxidation. “We now have examples of five or six different types of tumors that need this protein to proliferate,” Mittler said. “If they don’t have it, they die.”

    The team also discovered through experiments that expression of an NAF-1 protein that carried a single-point mutation had a similarly toxic effect on cancer cells and prevented tumor proliferation.

    Study co-author Rachel Nechushtai, a professor at the Hebrew University of Jerusalem, said tumors depend on the lability, or the transient nature, of the clusters. “The more NAF-1 you make, and the more its clusters can be transferred, the bigger the tumor develops.

    “We knew from previous studies that pioglitazone stabilizes the cluster. With the mutant, we hardly got any tumors and didn’t see angiogenesis (the process through which new blood vessels form). When we did see tumors, they were white, not red, because they had no blood vessels.

    “We thought, ‘How do we connect this to the clinics?’ The only connection was to try a drug that, like the mutation, also stabilizes the cluster,” she said. “Fang showed in her simulations where the binding site is and why the drug stabilizes the cluster.”

    “This is where the initial results from Fang are very nice, because she can show exactly how to modify the drug,” said Onuchic, whose lab specializes in predicting protein folding pathways through computer modeling. “That way, one can computationally design the drug before trying to make the real drug. It’s a much less expensive way to come up with possibilities.”

    Bai said, “We can design selective drugs that only bind to NAF-1 and not to other proteins to reduce the side effects based on our new method.”

    Lu, Merav Darash-Yahana of Hebrew University of Jerusalem and Yair Pozniak of Tel Aviv University are lead authors of the paper. Co-authors are Yang-Sung Sohn, Ola Karmi and Sagi Tamir of Hebrew University of Jerusalem, Luhua Song of the University of North Texas, Eli Pikarsky of the Hebrew University-Hadassah Medical School and Tamar Geiger of Tel Aviv University.

    The research was supported by the Israel Science Foundation, the University of North Texas College of Arts and Sciences, the Israel Cancer Research Fund, the National Science Foundation, the Cancer Prevention and Research Institute of Texas, the Keck Center for Interdisciplinary Bioscience Training of the Gulf Coast Consortia, the Welch Foundation and the National Institutes of Health.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 6:52 am on September 6, 2016 Permalink | Reply
    Tags: , , Nanodiamonds in an instant, , Rice U   

    From Rice: “Nanodiamonds in an instant” 

    Rice U bloc

    Rice University

    September 6, 2016

    David Ruth
    713-348-6327
    david@rice.edu

    Mike Williams
    713-348-6728
    mikewilliams@rice.edu

    Rice University-led team morphs nanotubes into tougher carbon for spacecraft, satellites

    1
    Experiments at Rice University showed nanodiamonds and other forms of carbon were created when carbon nanotube pellets were fired at a target at hypervelocity. (Credit: Illustration by Pedro Alves da Silva Autreto)

    Superman can famously make a diamond by crushing a chunk of coal in his hand, but Rice University scientists are employing a different tactic.

    Rice materials scientists are making nanodiamonds and other forms of carbon by smashing nanotubes against a target at high speeds. Nanodiamonds won’t make anyone rich, but the process of making them will enrich the knowledge of engineers who design structures that resist damage from high-speed impacts.

    The diamonds are the result of a detailed study on the ballistic fracturing of carbon nanotubes at different velocities. The results showed that such high-energy impacts caused atomic bonds in the nanotubes to break and sometimes recombine into different structures.

    The work led by the labs of materials scientists Pulickel Ajayan at Rice and Douglas Galvao at the State University of Campinas, Brazil, is intended to help aerospace engineers design ultralight materials for spacecraft and satellites that can withstand impacts from high-velocity projectiles like micrometeorites.

    The research appears in the American Chemical Society journal ACS Applied Materials and Interfaces.

    Knowing how the atomic bonds of nanotubes can be recombined will give scientists clues to develop lightweight materials by rearranging those bonds, said co-lead author and Rice graduate student Sehmus Ozden.

    “Satellites and spacecraft are at risk of various destructive projectiles, such as micrometeorites and orbital debris,” Ozden said. “To avoid this kind of destructive damage, we need lightweight, flexible materials with extraordinary mechanical properties. Carbon nanotubes can offer a real solution.”

    The researchers packed multiwalled carbon nanotubes into spherical pellets and fired them at an aluminum target in a two-stage light-gas gun at Rice, and then analyzed the results from impacts at three different speeds.

    At what the researchers considered a low velocity of 3.9 kilometers per second, a large number of nanotubes were found to remain intact. Some even survived higher velocity impacts of 5.2 kilometers per second. But very few were found among samples smashed at a hypervelocity of 6.9 kilometers per second. The researchers found that many, if not all, of the nanotubes split into nanoribbons, confirming earlier experiments.

    Co-author Chandra Sekhar Tiwary, a Rice postdoctoral researcher, noted the few nanotubes and nanoribbons that survived the impact were often welded together, as observed in transmission electron microscope images.

    “In our previous report, we showed that carbon nanotubes form graphene nanoribbons at hypervelocity impact,” Tiwary said. “We were expecting to get welded carbon nanostructures, but we were surprised to observe nanodiamond as well.”

    The orientation of nanotubes both to each other and in relation to the target and the number of tube walls were as important to the final structures as the velocity, Ajayan said.

    “The current work opens a new way to make nanosize materials using high-velocity impact,” said co-lead author Leonardo Machado of the Brazil team.

    Machado is a graduate student at the State University of Campinas, Brazil, and the Federal University of Rio Grande do Norte, Brazil. Co-authors are Rice’s Robert Vajtai, an associate research professor, and Enrique Barrera, a professor of materials science and nanoengineering, and Pedro Alves da Silva of the State University of Campinas and the Federal University of ABC, Santo Andre, Brazil. Ajayan is chair of Rice’s Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry.

    The research was supported by the Department of Defense, the U.S. Air Force Office of Scientific Research and its Multidisciplinary University Research Initiative, NASA’s Johnson Space Center, the Sao Paulo Research Foundation, the Center for Computational Engineering and Sciences at Unicamp, Brazil, and the Brazilian Federal Agency for Support and Evaluation of Graduate Education.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 11:31 am on September 5, 2016 Permalink | Reply
    Tags: , , , Rice U, Study: Earth’s carbon points to planetary smashup   

    From Rice- “Study: Earth’s carbon points to planetary smashup” 

    Rice U bloc

    Rice University

    September 5, 2016
    Jade Boyd

    Element ratios suggest Earth collided with Mercury-like planet

    1
    The ratio of volatile elements in Earth’s mantle suggests that virtually all of the planet’s life-giving carbon came from a collision with an embryonic planet approximately 100 million years after Earth formed. (Image by A. Passwaters/Rice University based on original courtesy of NASA/JPL-Caltech at http://www.nasa.gov/multimedia/imagegallery/image_feature_1454.html)

    Research by Rice University Earth scientists suggests that virtually all of Earth’s life-giving carbon could have come from a collision about 4.4 billion years ago between Earth and an embryonic planet similar to Mercury.

    In a new study this week in Nature Geoscience, Rice petrologist Rajdeep Dasgupta and colleagues offer a new answer to a long-debated geological question: How did carbon-based life develop on Earth, given that most of the planet’s carbon should have either boiled away in the planet’s earliest days or become locked in Earth’s core?

    “The challenge is to explain the origin of the volatile elements like carbon that remain outside the core in the mantle portion of our planet,” said Dasgupta, who co-authored the study with lead author and Rice postdoctoral researcher Yuan Li, Rice research scientist Kyusei Tsuno and Woods Hole Oceanographic Institute colleagues Brian Monteleone and Nobumichi Shimizu.

    Dasgupta’s lab specializes in recreating the high-pressure and high-temperature conditions that exist deep inside Earth and other rocky planets. His team squeezes rocks in hydraulic presses that can simulate conditions about 250 miles below Earth’s surface or at the core-mantle boundary of smaller planets like Mercury.

    “Even before this paper, we had published several studies that showed that even if carbon did not vaporize into space when the planet was largely molten, it would end up in the metallic core of our planet, because the iron-rich alloys there have a strong affinity for carbon,” Dasgupta said.

    Earth’s core, which is mostly iron, makes up about one-third of the planet’s mass. Earth’s silicate mantle accounts for the other two-thirds and extends more than 1,500 miles below Earth’s surface. Earth’s crust and atmosphere are so thin that they account for less than 1 percent of the planet’s mass. The mantle, atmosphere and crust constantly exchange elements, including the volatile elements needed for life.

    If Earth’s initial allotment of carbon boiled away into space or got stuck in the core, where did the carbon in the mantle and biosphere come from?

    “One popular idea has been that volatile elements like carbon, sulfur, nitrogen and hydrogen were added after Earth’s core finished forming,” said Li, who is now a staff scientist at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences. “Any of those elements that fell to Earth in meteorites and comets more than about 100 million years after the solar system formed could have avoided the intense heat of the magma ocean that covered Earth up to that point.

    “The problem with that idea is that while it can account for the abundance of many of these elements, there are no known meteorites that would produce the ratio of volatile elements in the silicate portion of our planet,” Li said.

    In late 2013, Dasgupta’s team began thinking about unconventional ways to address the issue of volatiles and core composition, and they decided to conduct experiments to gauge how sulfur or silicon might alter the affinity of iron for carbon. The idea didn’t come from Earth studies, but from some of Earth’s planetary neighbors.

    “We thought we definitely needed to break away from the conventional core composition of just iron and nickel and carbon,” Dasgupta recalled. “So we began exploring very sulfur-rich and silicon-rich alloys, in part because the core of Mars is thought to be sulfur-rich and the core of Mercury is thought to be relatively silicon-rich.

    2
    Schematic depiction of proto Earth’s merger with a potentially Mercury-like planetary embryo, a scenario supported by new high pressure-temperature experiments at Rice University. Magma ocean processes could lead planetary embryos to develop silicon- or sulfur-rich metallic cores and carbon-rich outer layers. If Earth merged with such a planet early in its history, it could explain how Earth acquired its carbon and sulfur. (Figure courtesy of Rajdeep Dasgupta)

    “It was a compositional spectrum that seemed relevant, if not for our own planet, then definitely in the scheme of all the terrestrial planetary bodies that we have in our solar system,” he said.

    The experiments revealed that carbon could be excluded from the core — and relegated to the silicate mantle — if the iron alloys in the core were rich in either silicon or sulfur.

    “The key data revealed how the partitioning of carbon between the metallic and silicate portions of terrestrial planets varies as a function of the variables like temperature, pressure and sulfur or silicon content,” Li said.

    The team mapped out the relative concentrations of carbon that would arise under various levels of sulfur and silicon enrichment, and the researchers compared those concentrations to the known volatiles in Earth’s silicate mantle.

    “One scenario that explains the carbon-to-sulfur ratio and carbon abundance is that an embryonic planet like Mercury, which had already formed a silicon-rich core, collided with and was absorbed by Earth,” Dasgupta said. “Because it’s a massive body, the dynamics could work in a way that the core of that planet would go directly to the core of our planet, and the carbon-rich mantle would mix with Earth’s mantle.

    “In this paper, we focused on carbon and sulfur,” he said. “Much more work will need to be done to reconcile all of the volatile elements, but at least in terms of the carbon-sulfur abundances and the carbon-sulfur ratio, we find this scenario could explain Earth’s present carbon and sulfur budgets.”

    The research was supported by NASA and the National Science Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
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