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  • richardmitnick 10:01 am on January 26, 2022 Permalink | Reply
    Tags: "Using nanodiamonds as sensors just got easier", , , Excited state lifetime thermometry, , , , , Nitrogen vacancy centers, ODMR: optically detected magnetic resonance, , , , The University of Rochester(US), Transmission electron microscopy   

    From The University of Rochester(US): “Using nanodiamonds as sensors just got easier” 

    From The University of Rochester(US)

    January 25, 2022

    Bob Marcotte
    bmarcotte@ur.rochester.edu

    Rochester researchers find new way to extract temperature from light emitted by a diamond defect.

    1
    University of Rochester PhD student Dinesh Bommidi (left) and Andrea Pickel, an assistant professor of mechanical engineering, used an atomic force microscope to locate and move nanodiamond sensors. Photo: J. Adam Fenster/University of Rochester.

    For centuries people have placed the highest value on diamonds that are not only large but flawless.

    Scientists, however, have discovered exciting new applications for diamonds that are not only incredibly small but have a unique defect.

    In a recent paper in Applied Physics Letters, researchers at the University of Rochester describe a new way to measure temperature with these defects, called nitrogen vacancy centers, using the light they emit. The technique, adapted for single nanodiamonds by Andrea Pickel, assistant professor of mechanical engineering, and Dinesh Bommidi, a PhD student in her lab, allowed them to precisely measure, for the first time, the duration of these light emissions, or “excited state lifetimes,” at a broad range of temperatures.

    The discovery earned the paper recognition as an American Institute of Physics (US) Scilight, a showcase of what AIP considers the most interesting research across the physical sciences.

    The Rochester method gives researchers a less complicated, more accurate tool for using nitrogen vacancy centers to measure the temperature of nanoscale-sized materials. The approach is also safe for imaging sensitive nanoscale materials or biological tissues and could have applications in quantum information processing.

    For example, Pickel says, the technique could help define and measure the precise optimal temperatures needed to switch the resistivity of materials in nanoscale-sized phase change memory devices as part of the ongoing quest to store ever larger amounts of data in ever smaller devices.

    “These excited state lifetime measurements are really helpful for measuring temperature changes that take place not only over small length scales, but also on fast time scales,” Pickel says. “It turns out these lifetimes are quite fast—only about 25 to 30 nanoseconds at room temperature, and even faster at higher temperatures.”

    2
    NANADIAMONDS ARE A SCIENTIST’S BEST FRIEND? Left: A transmission electron microscope image shows a single nanodiamond with a 70-nanometer diamond core on a carbon grid. Rochester researchers have developed a new way to use defects in diamonds called nitrogen vacancy centers to measure the temperature of the samples they are attached to with outstanding spatial and temporal resolution. Right: An atomic force microscope (AFM) image shows nanodiamonds arranged in an “R” (for Rochester) pattern using AFM nanomanipulation. Credit: Pickel Lab images.

    New technique offers multiple advantages over standard approach

    Nitrogen vacancy centers are often created by bombarding commercial diamonds with ions, then milling them down into the nanoscale diamond particles used by researchers. In a nitrogen vacancy center, one of the carbon atoms is replaced with a nitrogen atom, and the adjoining nitrogen atom is missing. “It turns out, these nitrogen vacancy centers are fluorescent, so if you send light in—from a laser, for example—you can also get light out of them,” Pickel says.

    To date, most research groups have used a technique called optically detected magnetic resonance (ODMR) to measure temperature using nitrogen vacancy centers. However, the method has several drawbacks, Pickel says. OMDR requires placing a microwave antenna near the sample to do the measurements. That can be a complicated setup. The antenna can also cause heating that could harm sensitive materials or biological samples. Moreover, the microwave signal can be lost altogether at higher temperatures.

    Instead, Pickel and Bommidi adapted an existing technique called excited state lifetime thermometry and applied it to nitrogen vacancy centers in single nanodiamonds for the first time.

    The nanodiamonds, scattered on the surface of a material to be tested, are located using atomic force microscopy. The researchers developed a way to use the microscope probe tip to then move individual nanodiamonds to desired locations.

    3
    GIVE IT THE GREEN LIGHT: Close-up of the laser system in Andrea Pickel’s lab, located in Hopeman Hall. The researchers use green laser pulses to excite the nitrogen vacancy centers in the nanodiamonds in order to send the electrons into a higher energy state. Photo: J. Adam Fenster/University of Rochester.

    “If you know there’s a really critical location where you want to measure the temperature on a device or sample, this gives us a way to move the nanodiamond sensor to exactly that spot—almost like using a putter in a little nanodiamond golf game,” Pickel says.

    The researchers then excite the nitrogen vacancy centers with green laser pulses. This sends electrons into a higher energy state. When the laser shuts off and the electrons return to a normal state, photons are emitted. The duration of this emission is a precise indicator of temperature.

    Because the nanodiamonds are the same temperature as the material they are placed on, the readings are accurate for the material as well, Pickel says.

    “We are excited about this because it is all optical; we don’t need to have a microwave antenna,” Pickel says. “And even when we increase the temperature, we retain access to our measurement signal, so we can make temperature measurements at pretty fast time scales. That’s important at the nanoscale, because when you have really small samples, they can change temperatures really fast.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    University of Rochester campus

    The University of Rochester (US) is a private research university in Rochester, New York. The university grants undergraduate and graduate degrees, including doctoral and professional degrees.

    The University of Rochester (US) enrolls approximately 6,800 undergraduates and 5,000 graduate students. Its 158 buildings house over 200 academic majors. According to the National Science Foundation (US), Rochester spent $370 million on research and development in 2018, ranking it 68th in the nation. The university is the 7th largest employer in the Finger lakes region of New York.

    The College of Arts, Sciences, and Engineering is home to departments and divisions of note. The Institute of Optics was founded in 1929 through a grant from Eastman Kodak and Bausch and Lomb as the first educational program in the US devoted exclusively to optics and awards approximately half of all optics degrees nationwide and is widely regarded as the premier optics program in the nation and among the best in the world.

    The Departments of Political Science and Economics have made a significant and consistent impact on positivist social science since the 1960s and historically rank in the top 5 in their fields. The Department of Chemistry is noted for its contributions to synthetic organic chemistry, including the first lab based synthesis of morphine. The Rossell Hope Robbins Library serves as the university’s resource for Old and Middle English texts and expertise. The university is also home to Rochester’s Laboratory for Laser Energetics, a Department of Energy (US) supported national laboratory.

    University of Rochester(US) Laboratory for Laser Energetics.

    The University of Rochester’s Eastman School of Music (US) ranks first among undergraduate music schools in the U.S. The Sibley Music Library at Eastman is the largest academic music library in North America and holds the third largest collection in the United States.

    In its history university alumni and faculty have earned 13 Nobel Prizes; 13 Pulitzer Prizes; 45 Grammy Awards; 20 Guggenheim Awards; 5 National Academy of Sciences; 4 National Academy of Engineering; 3 Rhodes Scholarships; 3 National Academy of Inventors; and 1 National Academy of Inventors Hall of Fame.

    History

    Early history

    The University of Rochester traces its origins to The First Baptist Church of Hamilton (New York) which was founded in 1796. The church established the Baptist Education Society of the State of New York later renamed the Hamilton Literary and Theological Institution in 1817. This institution gave birth to both Colgate University(US) and the University of Rochester. Its function was to train clergy in the Baptist tradition. When it aspired to grant higher degrees it created a collegiate division separate from the theological division.

    The collegiate division was granted a charter by the State of New York in 1846 after which its name was changed to Madison University. John Wilder and the Baptist Education Society urged that the new university be moved to Rochester, New York. However, legal action prevented the move. In response, dissenting faculty, students, and trustees defected and departed for Rochester, where they sought a new charter for a new university.

    Madison University was eventually renamed as Colgate University (US).

    Founding

    Asahel C. Kendrick- professor of Greek- was among the faculty that departed Madison University for Rochester. Kendrick served as acting president while a national search was conducted. He reprised this role until 1853 when Martin Brewer Anderson of the Newton Theological Seminary in Massachusetts was selected to fill the inaugural posting.

    The University of Rochester’s new charter was awarded by the Regents of the State of New York on January 31, 1850. The charter stipulated that the university have $100,000 in endowment within five years upon which the charter would be reaffirmed. An initial gift of $10,000 was pledged by John Wilder which helped catalyze significant gifts from individuals and institutions.

    Classes began that November with approximately 60 students enrolled including 28 transfers from Madison. From 1850 to 1862 the university was housed in the old United States Hotel in downtown Rochester on Buffalo Street near Elizabeth Street- today West Main Street near the I-490 overpass. On a February 1851 visit Ralph Waldo Emerson said of the university:

    “They had bought a hotel, once a railroad terminus depot, for $8,500, turned the dining room into a chapel by putting up a pulpit on one side, made the barroom into a Pythologian Society’s Hall, & the chambers into Recitation rooms, Libraries, & professors’ apartments, all for $700 a year. They had brought an omnibus load of professors down from Madison bag and baggage… called in a painter and sent him up the ladder to paint the title “University of Rochester” on the wall, and they had runners on the road to catch students. And they are confident of graduating a class of ten by the time green peas are ripe.”

    For the next 10 years the college expanded its scope and secured its future through an expanding endowment; student body; and faculty. In parallel a gift of 8 acres of farmland from local businessman and Congressman Azariah Boody secured the first campus of the university upon which Anderson Hall was constructed and dedicated in 1862. Over the next sixty years this Prince Street Campus grew by a further 17 acres and was developed to include fraternities houses; dormitories; and academic buildings including Anderson Hall; Sibley Library; Eastman and Carnegie Laboratories the Memorial Art Gallery and Cutler Union.

    Twentieth century

    Coeducation

    The first female students were admitted in 1900- the result of an effort led by Susan B. Anthony and Helen Barrett Montgomery. During the 1890s a number of women took classes and labs at the university as “visitors” but were not officially enrolled nor were their records included in the college register. President David Jayne Hill allowed the first woman- Helen E. Wilkinson- to enroll as a normal student although she was not allowed to matriculate or to pursue a degree. Thirty-three women enrolled among the first class in 1900 and Ella S. Wilcoxen was the first to receive a degree in 1901. The first female member of the faculty was Elizabeth Denio who retired as Professor Emeritus in 1917. Male students moved to River Campus upon its completion in 1930 while the female students remained on the Prince Street campus until 1955.

    Expansion

    Major growth occurred under the leadership of Benjamin Rush Rhees over his 1900-1935 tenure. During this period George Eastman became a major donor giving more than $50 million to the university during his life. Under the patronage of Eastman the Eastman School of Music (US) was created in 1921. In 1925 at the behest of the General Education Board and with significant support for John D. Rockefeller George Eastman and Henry A. Strong’s family medical and dental schools were created. The university award its first Ph.D that same year.

    During World War II University of Rochester was one of 131 colleges and universities nationally that took part in the V-12 Navy College Training Program which offered students a path to a Navy commission. In 1942, the university was invited to join the Association of American Universities(US) as an affiliate member and it was made a full member by 1944. Between 1946 and 1947 in infamous uranium experiments researchers at the university injected uranium-234 and uranium-235 into six people to study how much uranium their kidneys could tolerate before becoming damaged.

    In 1955 the separate colleges for men and women were merged into The College on the River Campus. In 1958 three new schools were created in engineering; business administration and education. The Graduate School of Management was named after William E. Simon- former Secretary of the Treasury in 1986. He committed significant funds to the school because of his belief in the school’s free market philosophy and grounding in economic analysis.

    Financial decline and name change controversy

    Following the princely gifts given throughout his life George Eastman left the entirety of his estate to the university after his death by suicide. The total of these gifts surpassed $100 million before inflation and as such Rochester enjoyed a privileged position amongst the most well endowed universities. During the expansion years between 1936 and 1976 the University of Rochester’s financial position ranked third, near Harvard University’s(US) endowment and the University of Texas (US) System’s Permanent University Fund. Due to a decline in the value of large investments and a lack of portfolio diversity the university’s place dropped to the top 25 by the end of the 1980s. At the same time the preeminence of the city of Rochester’s major employers began to decline.

    In response the University commissioned a study to determine if the name of the institution should be changed to “Eastman University” or “Eastman Rochester University”. The study concluded a name change could be beneficial because the use of a place name in the title led respondents to incorrectly believe it was a public university, and because the name “Rochester” connoted a “cold and distant outpost.” Reports of the latter conclusion led to controversy and criticism in the Rochester community. Ultimately, the name “University of Rochester” was retained.

    Renaissance Plan
    In 1995 University of Rochester president Thomas H. Jackson announced the launch of a “Renaissance Plan” for The College that reduced enrollment from 4,500 to 3,600 creating a more selective admissions process. The plan also revised the undergraduate curriculum significantly creating the current system with only one required course and only a few distribution requirements known as clusters. Part of this plan called for the end of graduate doctoral studies in chemical engineering; comparative literature; linguistics; and mathematics the last of which was met by national outcry. The plan was largely scrapped and mathematics exists as a graduate course of study to this day.

    Twenty-first century

    Meliora Challenge

    Shortly after taking office university president Joel Seligman commenced the private phase of the “Meliora Challenge”- a $1.2 billion capital campaign- in 2005. The campaign reached its goal in 2015- a year before the campaign was slated to conclude. In 2016, the university announced the Meliora Challenge had exceeded its goal and surpassed $1.36 billion. These funds were allocated to support over 100 new endowed faculty positions and nearly 400 new scholarships.

    The Mangelsdorf Years

    On December 17, 2018 the University of Rochester announced that Sarah C. Mangelsdorf would succeed Richard Feldman as President of the University. Her term started in July 2019 with a formal inauguration following in October during Meliora Weekend. Mangelsdorf is the first woman to serve as President of the University and the first person with a degree in psychology to be appointed to Rochester’s highest office.

    In 2019 students from China mobilized by the Chinese Students and Scholars Association (CSSA) defaced murals in the University’s access tunnels which had expressed support for the 2019 Hong Kong Protests, condemned the oppression of the Uighurs, and advocated for Taiwanese independence. The act was widely seen as a continuation of overseas censorship of Chinese issues. In response a large group of students recreated the original murals. There have also been calls for Chinese government run CSSA to be banned from campus.

    Research

    Rochester is a member of the Association of American Universities (US) and is classified among “R1: Doctoral Universities – Very High Research Activity”.

    Rochester had a research expenditure of $370 million in 2018.

    In 2008 Rochester ranked 44th nationally in research spending but this ranking has declined gradually to 68 in 2018.

    Some of the major research centers include the Laboratory for Laser Energetics, a laser-based nuclear fusion facility, and the extensive research facilities at the University of Rochester Medical Center.

    Recently the university has also engaged in a series of new initiatives to expand its programs in biomedical engineering and optics including the construction of the new $37 million Robert B. Goergen Hall for Biomedical Engineering and Optics on the River Campus.

    Other new research initiatives include a cancer stem cell program and a Clinical and Translational Sciences Institute. UR also has the ninth highest technology revenue among U.S. higher education institutions with $46 million being paid for commercial rights to university technology and research in 2009. Notable patents include Zoloft and Gardasil. WeBWorK, a web-based system for checking homework and providing immediate feedback for students was developed by University of Rochester professors Gage and Pizer. The system is now in use at over 800 universities and colleges as well as several secondary and primary schools. Rochester scientists work in diverse areas. For example, physicists developed a technique for etching metal surfaces such as platinum; titanium; and brass with powerful lasers enabling self-cleaning surfaces that repel water droplets and will not rust if tilted at a 4 degree angle; and medical researchers are exploring how brains rid themselves of toxic waste during sleep.

     
  • richardmitnick 9:11 am on May 28, 2021 Permalink | Reply
    Tags: "Engineered defects in crystalline material boosts electrical performance", , , Iowa State University (US), Key to the project was the Ames Laboratory’s sensitive Instrument Facility., , Materials engineering, The engineered defects led to a five-fold increase in dielectric properties (that restrict the flow of current) and a 19-fold increase in piezoelectric properties., The finding could have big implications for the electrical capacitor industry., Transmission electron microscopy   

    From Iowa State University (US) : “Engineered defects in crystalline material boosts electrical performance” 

    From Iowa State University (US)

    5.27.21

    1
    Xiaoli Tan and a team of campus collaborators used this transmission electron microscope at the Ames Laboratory’s Sensitive Instrument Facility to study the effects of engineering defects into certain materials.
    Credit: Christopher Gannon.

    Materials engineers don’t like to see line defects in functional materials.

    The structural flaws along a one-dimensional line of atoms generally degrades performance of electrical materials. So, as a research paper published today by the journal Science reports, these linear defects, or dislocations, “are usually avoided at all costs.”

    But sometimes, a team of researchers from Europe, Iowa State University and the DOE’s Ames Laboratory (US) report in that paper, engineering those defects in some oxide crystals can actually increase electrical performance.

    The research team – led by Jürgen Rödel and Jurij Koruza of the Technical University of Darmstadt [Technische Universität Darmstadt] (DE) in Germany – found certain defects produce significant improvements in two key measurements of electrical performance in barium titanate, a crystalline ceramic material.

    “By introducing these defects into the material, we can change, modify or improve the material’s functional properties,” said Xiaoli Tan, an Iowa State professor of materials science and engineering and a longtime research collaborator with Rödel.

    In this case, the engineered defects led to a five-fold increase in dielectric properties (that restrict the flow of current) and a 19-fold increase in piezoelectric properties (that internally generates an electric field when subject to mechanical stress), Tan said.

    Special tools for special measurements

    In addition to Tan, two other Iowa State researchers helped the project’s international research team explore fundamental materials questions: Lin Zhou, a scientist in materials science and engineering and the U.S. Department of Energy’s Ames Laboratory; and Binzhi Liu, a doctoral student in materials science and engineering.

    With support from the National Science Foundation (US), the three contributed their expertise in transmission electron microscopy – technology that can show the structures and features of materials by shooting a beam of electrons through thin samples and recording an image. The images have much higher resolution than light microscopy and can show fine details down to the scale of individual atoms.

    Key to the project was the Ames Laboratory’s Sensitive Instrument Facility built in cooperation with Iowa State. The building was built in 2015 with nearly $10 million from the Department of Energy (US). It provides a vibration- and static-free environment for electron microscopy at the highest possible resolutions.

    “It’s a state-of-the-art electron microscopy facility,” Zhou said. “It provides an ultra-stable environment so we can achieve atom-level images of material and at the same time acquire chemical information.

    “It’s a great platform for research and educating the next generation of materials scientists.”

    A better material for capacitors?

    For this project, the electron microscopy team quantified the evidence that line defects in a crystalline material can boost electrical performance, Liu said.

    The numbers showed that “the dislocations can significantly alter the behavior of other fine features in the material,” Liu said.

    Tan said the finding could have big implications for the electrical capacitor industry.

    There are hundreds of capacitors in your cell phone and the market for them is huge, Tan said. The ceramic material tested in this project has been widely used in capacitors, but the defect-induced boost in electrical performance could make it better. It is also lead-free and less-toxic than other material options.

    And so, the researchers wrote, these engineered line defects could turn into “a different suite of tools to tailor functional materials.” And this “functional harvesting” could be good for our electronics, and even our environment and health.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Iowa State University (US) is a public, land-grant university, where students get a great academic start in learning communities and stay active in 800-plus student organizations, undergrad research, internships and study abroad. They learn from world-class scholars who are tackling some of the world’s biggest challenges — feeding the hungry, finding alternative fuels and advancing manufacturing.

    Iowa Agricultural College and Model Farm (now Iowa State University) was officially established on March 22, 1858, by the legislature of the State of Iowa. Story County was selected as a site on June 21, 1859, and the original farm of 648 acres was purchased for a cost of $5,379. The Farm House, the first building on the Iowa State campus, was completed in 1861, and in 1862, the Iowa legislature voted to accept the provision of the Morrill Act, which was awarded to the agricultural college in 1864.

    Iowa State University Knapp-Wilson Farm House. Photo between 1911-1926

    Iowa Agricultural College (Iowa State College of Agricultural and Mechanic Arts as of 1898), as a land grant institution, focused on the ideals that higher education should be accessible to all and that the university should teach liberal and practical subjects. These ideals are integral to the land-grant university.

    The first official class entered at Ames in 1869, and the first class (24 men and 2 women) graduated in 1872. Iowa State was and is a leader in agriculture, engineering, extension, home economics, and created the nation’s first state veterinary medicine school in 1879.

    In 1959, the college was officially renamed Iowa State University of Science and Technology. The focus on technology has led directly to many research patents and inventions including the first binary computer (the ABC), Maytag blue cheese, the round hay baler, and many more.

    Beginning with a small number of students and Old Main, Iowa State University now has approximately 27,000 students and over 100 buildings with world class programs in agriculture, technology, science, and art.

    Iowa State University is a very special place, full of history. But what truly makes it unique is a rare combination of campus beauty, the opportunity to be a part of the land-grant experiment, and to create a progressive and inventive spirit that we call the Cyclone experience. Appreciate what we have here, for it is indeed, one of a kind.

     
  • richardmitnick 5:14 pm on December 22, 2020 Permalink | Reply
    Tags: "New electron microscopy technique offers first look at previously hidden processes", , , , , , Transmission electron microscopy   

    From Northwestern University: “New electron microscopy technique offers first look at previously hidden processes” 

    Northwestern U bloc
    From Northwestern University

    December 22, 2020
    Mark Heiden

    1
    A schematic depiction of virtual electron–positron pairs appearing at random near an electron (at lower left). Credit: RJHall/Wikipedia.

    Researchers can now fill in missing information about nanoscale polymerization and “smart” materials for medicine and the environment.

    Northwestern researchers have developed a new microscopy method that allows scientists to see the building blocks of “smart” materials being formed at the nanoscale.

    The chemical process is set to transform the future of clean water and medicines and for the first time people will be able to watch the process in action.

    “Our method allows us to visualize this class of polymerization in real time, at the nanoscale, which has never been done before,” said Northwestern’s Nathan Gianneschi. “We now have the ability to see the reaction taking place, see these nanostructures being formed, and learn how to take advantage of the incredible things they can do.”

    The research was published today (Dec. 22) in the journal Matter.

    The paper is the result of a collaboration between Gianneschi, the associate director of the International Institute for Nanotechnology and the Jacob and Rosalind Cohn Professor of Chemistry in the Weinberg College of Arts and Sciences, and Brent Sumerlin, the George and Josephine Butler Professor of Polymer Chemistry in the College of Liberal Arts & Sciences at the University of Florida.

    Dispersion polymerization is a common scientific process used to make medicines, cosmetics, latex and other items, often on an industrial scale. And at the nanoscale, polymerization can be used to create nanoparticles with unique and valuable properties.

    These nanomaterials hold great promise for the environment, where they can be used to soak up oil spills or other pollutants without harming marine life. In medicine, as the foundation of “smart” drug delivery systems, it can be designed to enter human cells and release therapeutic molecules under specified conditions.

    There have been difficulties in scaling up production of these materials. Initially, production was hampered by the time-consuming process required to create and then activate them. A technique called polymerization-induced self-assembly (PISA) combines steps and saves time, but the molecules’ behavior during this process has proven difficult to predict for one simple reason: Scientists were unable to observe what was actually happening.

    Reactions at the nanoscale are far too small to be seen with the naked eye. Traditional imaging methods can only capture the end result of polymerization, not the process by which it occurs. Scientists have tried to work around this by taking samples at various points in the process and analyzing them, but using only snapshots failed to tell the full story of chemical and physical changes occurring throughout the process.

    “It’s like comparing a few photos of a football game to the information contained in a video of the whole game,” said Gianneschi. “If you understand the pathway by which a chemical forms, if you can see how it occurred, then you can learn how to speed it up, and you can figure out how to perturb the process so you get a different effect.”

    Transmission electron microscopy (TEM) is capable of taking images at a sub-nanometer resolution, but it is generally used for frozen samples, and doesn’t handle chemical reactions as well. With TEM, an electron beam is fired through a vacuum, toward the subject; by studying the electrons that come out the other side, an image can be developed. However, the quality of the image depends on how many electrons are fired by the beam – and firing too many electrons will affect the outcome of the chemical reaction. In other words, it’s a case of the observer effect – watching the self-assembly could alter or even damage the self-assembly. What you end up with is different from what you would have had if you weren’t watching.

    To solve the problem, the researchers inserted the nanoscale polymer materials into a closed liquid cell that would protect the materials from the vacuum inside the electron microscope. These materials were designed to be responsive to changes in temperature, so the self-assembly would begin when the inside of the liquid cell reached a set temperature.

    The liquid cell was enclosed in a silicon chip with small, but powerful, electrodes that serve as heating elements. Embedded in the chip is a tiny window – 200 x 50 nanometers in size – that would allow a low-energy beam to pass through the liquid cell.

    With the chip inserted into the holder of the electron microscope, the temperature inside the liquid cell is raised to 60˚C, initiating the self-assembly. Through the tiny window, the behavior of the block copolymers and the process of formation could be recorded.

    When the process was complete, Gianneschi’s team tested the resulting nanomaterials and found they were the same as comparable nanomaterials produced outside a liquid cell. This confirmed that the technique – which they call variable-temperature liquid-cell transmission electron microscopy (VC-LCTEM) – can be used to understand the nanoscale polymerization process as it occurs under ordinary conditions.

    Of particular interest are the shapes that are generated during polymerization. At different stages the nanoparticles may resemble spheres, worms or jellyfish – each of which confers different properties upon the nanomaterial. By understanding what is happening during self-assembly researchers can begin to develop methods to induce specific shapes and tune their effects.

    “These intricate and well-defined nanoparticles evolve over time, forming and then morphing as they grow,” Sumerlin said. “What’s incredible is that we’re able to see both how and when these transitions occur in real time.”

    Gianneschi believes that insights gained from this technique will lead to unprecedented possibilities for the development and characterization of self-organizing soft matter materials – and scientific disciplines beyond chemistry.

    “We think this can become a tool that’s useful in structural biology and materials science too,” said Gianneschi. “By integrating this with machine learning algorithms to analyze the images, and continuing to refine and improve the resolution, we’re going to have a technique that can advance our understanding of polymerization at the nanoscale and guide the design of nanomaterials that can potentially transform medicine and the environment.”

    Gianneschi is also a professor of biomedical engineering and materials science and engineering in the McCormick School of Engineering. He holds memberships at the Chemistry of Life Processes Institute, Simpson Querrey Institute, and Robert H. Lurie Comprehensive Cancer Center of Northwestern University. Sumerlin is also the acting director of the Center for Macromolecular Science & Engineering at the University of Florida.

    The study received support from the U.S. Department of Defense through the Army Research Office (W911NF-17-1-0326). Additional collaboration came from researchers at the University of California, San Diego.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    Northwestern is recognized nationally and internationally for its educational programs.

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

     
  • richardmitnick 8:46 am on September 16, 2019 Permalink | Reply
    Tags: , , , , Transmission electron microscopy, Xeuss 2.0 X-ray scattering instrument   

    From Penn Today: “Researchers think small to make progress towards better fuel cells” 


    From Penn Today

    September 13, 2019
    Erica K. Brockmeier
    Eric Sucar Photographer

    A collaborative study describes how fuel cells, which use chemical energy to power cars and devices, can be developed using nanomaterials to be more cost-effective and efficient in the long term.

    1
    Graduate student Jennifer Lee uses a large transmission electron microscope, housed in the Singh Center, to take a closer look at the nanomaterials and nanocrystals that are synthesized in the lab.

    As renewable sources such as wind and solar are quickly changing the energy landscape, scientists are looking for ways to better store energy for when it’s needed. Fuel cells, which convert chemical energy into electrical power, are one possible solution for long-term energy storage, and could someday be used to power trucks and cars without burning fuel. But before fuel cells can be widely used, chemists and engineers need to find ways to make this technology more cost-effective and stable.

    A new study from the lab of Penn Integrates Knowledge Professor Christopher Murray, led by graduate student Jennifer Lee, shows how custom-designed nanomaterials can be used to address these challenges. In ACS Applied Materials & Interfaces, researchers show how a fuel cell can be built from cheaper, more widely available metals using an atomic-level design that also gives the material long-term stability. Former post-doc Davit Jishkariani and former students Yingrui Zhao and Stan Najmr, current student Daniel Rosen, and professors James Kikkawa and Eric Stach, also contributed to this work.

    The chemical reaction that powers a fuel cell relies on two electrodes, a negative anode and a positive cathode, separated by an electrolyte, a substance that allows the ions to move. When fuel enters the anode, a catalyst separates molecules into protons and electrons, with the latter traveling toward the cathode and creating an electric current.

    Catalysts are typically made of precious metals, like platinum, but because the chemical reactions only occur on the surface of the material, any atoms that are not presented on the surface of the material are wasted. It’s also important for catalysts to be stable for months and years because fuel cells are very difficult to replace.

    Chemists can address these two problems by designing custom nanomaterials that have platinum at the surface while using more common metals, such as cobalt, in the bulk to provide stability. The Murray group excels at creating well-controlled nanomaterials, known as nanocrystals, in which they can control the size, shape, and composition of any composite nanomaterial.

    2
    When not busy at the microscope or analyzing data, researchers in the Murray group work on synthesizing new nanomaterials.

    In this study, Lee focused on the catalyst in the cathode of a specific type of fuel cell known as a proton exchange membrane fuel cell. “The cathode is more of a problem, because the materials are either platinum or platinum-based, which are expensive and have slower reaction rates,” she says. “Designing the catalyst for the cathode is the main focus of designing a good fuel cell.”

    The challenge, explains Jishkariani, was in creating a cathode in which platinum and cobalt atoms would form into a stable structure. “We know cobalt and platinum mixes well; however, if you make alloys of these two, you have added atoms of platinum and cobalt in a random order,” he says. Adding more cobalt in a random order causes it to leach out into the electrode, meaning that the fuel cell will only function for a short time.

    To solve this problem, researchers designed a catalyst made of layered platinum and cobalt known as an intermetallic phase. By controlling exactly where each atom sat in the catalyst and locking the structure in place, the cathode catalyst was able to work for longer periods than when the atoms were arranged randomly. As an additional unexpected finding, the researchers found that adding more cobalt to the system led to greater efficiency, with a 1-to-1 ratio of platinum to cobalt, better than many other structures with a wide range of platinum-to-cobalt ratios.

    The next step will be to test and evaluate the intermetallic material in fuel cell assemblies to make direct comparisons to commercially-available systems. The Murray group will also be working on new ways to create the intermetallic structure without high temperatures and seeing if adding additional atoms improve the catalyst’s performance.

    3
    The Xeuss 2.0 X-ray scattering instrument, which came to the LRSM in 2018, helps researchers characterize the structures of a wide range of hard and soft materials.

    This work required high-resolution microscopic imaging, work that Lee previously did at Brookhaven National Lab but, thanks to recent acquisitions, can now be done at Penn in the Singh Center for Nanotechnology. “Many of the high-end experiments that we would have had to travel to around the country, sometimes around the world, we can now do much closer to home,” says Murray. “The advances that we’ve brought in electron microscopy and X-ray scattering are a fantastic addition for people that work on energy conversion and catalytic studies.”

    Lee also experienced first-hand how chemistry research directly connects to real world challenges. She recently presented this work at the International Precious Metals Institute conference and says that meeting members of the precious-metals community was enlightening. “There are companies looking at fuel cell technology and talking about the newest design of the fuel cell cars,” she says. “You get to interact with people that think of your project from different perspectives.”

    Murray sees this fundamental research as a starting point towards commercial implementation and real world application, emphasizing that future progress relies on the forward-looking research that’s happening now. “Thinking about a world where we’ve displaced a lot of the traditional fossil fuel-based inputs, if we can figure out this interconversion of electrical and chemical energy, that will address a couple of very important problems simultaneously.”

    This research was supported by the U.S. Department of Energy Fuel Cell Technology Office. This research used resources of the Center for Functional Nanomaterials of the Brookhaven National Laboratory, supported by the U.S. Department of Energy Office of Science Graduate Student Research (SCGSR) program.


    BNL Center for Functional Nanomaterials

    Magnetic property measurements were supported by the National Science Foundation Materials Research Science and Engineering Center Grant DMR-1720530.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 3:22 pm on April 24, 2018 Permalink | Reply
    Tags: , LC-TEM liquid cell transmission electron microscopy, , Transmission electron microscopy   

    From Michigan Technical University: “Liquid Cell Transmission Electron Microscopy Makes a Window into the Nanoscale” 

    Michigan Tech bloc

    Michigan Technical University

    April 23, 2018
    Allison Mills
    awmills@mtu.edu
    906-487-2343

    From energy materials to disease diagnostics, new microscopy techniques can provide more nuanced insight. Researchers first need to understand the effects of radiation on samples.

    In a new paper published last week in Science Advances, a team of scientists and engineers dug into the mechanisms that degrade sample quality in liquid cell transmission electron microscopy (LC-TEM). They developed an LC-TEM device that uses multiple windows and patterned features to explore the impacts of high-energy electron bombardment on nanoparticles and sensitive biological samples.

    The collaborating institutions include the EMSL, the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Science User Facility at the Pacific Northwest National Laboratory (PNNL), University of Illinois Chicago, Florida State University, Washington State University and Michigan Technological University. The study’s lead author, Trevor Moser, currently at the PNNL, is a doctoral student at Michigan Tech studying under both Tolou Shokuhfar, an adjunct professor of mechanical engineering at Michigan Tech and an associate professor of bioengineering at the University of Illinois Chicago, and James Evans, a senior scientist at PNNL.

    The team explains that transmission electron microscopy (TEM) relies on a high-energy beam of electrons that passes through a sample. Whether the sample is from a battery electrode or bacterial cells, the passing electrons will scatter in a specific way reflecting the sample’s atomic structure. In LC-TEM, materials can be examined in a native state allowing dynamic observations, but the samples are liquid or suspended in liquid and have to be tightly sealed to withstand the space-like vacuum of the instrument. There is a balance between ensuring the liquid doesn’t evaporate while providing enough viewing space for the electron beam to pass through.

    “We have designed and fabricated new devices for holding liquid samples which give us more ‘window’ regions to collect images than were previously available,” Moser says. “Using these multiple windows, we were able to study how the history of electron irradiation influences the nucleation and growth of silver nanoparticles, the growth properties of which are sensitive to the radicals that are generated with the beam. We also used them to study how these radicals impact bacterial cells and demonstrate the extreme sensitivity of these biological samples to the electron beam.”

    1
    The research team created a tiny device that allows more of the microscope’s electron beam to pass through liquid samples. Image Credit: Pacific Northwest National Laboratory

    Irradiation from the high-energy beam used in LC-TEM can cause physical damage to samples. For example, the team found that when a cell was imaged—and was exposed to significant electron flux for the first time—observed nanoparticle movement relative to the cell membrane was a result of cell damage. That matters because the insight shows that the movement is an artifact of imaging the cell rather than watching cell dynamics happen in real-time.

    “We were able to capture pristine images of cells using our multi-chamber device wherein the first image represented the cells first exposure to significant electron doses,” Evans says.

    “Since the native properties of the sample may be altered or changed by the effects of these electron beam-generated radicals,” Shokuhfar adds, “understanding the chemistry changes of a liquid sample as a result of electron irradiation is key to correct interpretation of data collected with this technique.”

    As the nuances of LC-TEM are gleaned, possible applications include gathering extremely high-resolution, detailed information on energy device and storage materials as well as disease detection, medical imaging and digging deep into the basics of cell activity. In terms of next steps, the team plans to focus on characterizing more biological samples, which appear to be vulnerable to the effects of electron irradiation. The new LC-TEM device offers more windows into this complex atomic world, providing more chances for breakthroughs in energy and health.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    Michigan Tech Campus
    Michigan Technological University (http://www.mtu.edu) is a leading public research university developing new technologies and preparing students to create the future for a prosperous and sustainable world. Michigan Tech offers more than 130 undergraduate and graduate degree programs in engineering; forest resources; computing; technology; business; economics; natural, physical and environmental sciences; arts; humanities; and social sciences.
    The College of Sciences and Arts (CSA) fills one of the most important roles on the Michigan Tech campus. We play a part in the education of every student who comes through our doors. We take pride in offering essential foundational courses in the natural sciences and mathematics, as well as the social sciences and humanities—courses that underpin every major on campus. With twelve departments, 28 majors, 30-or-so specializations, and more than 50 minors, CSA has carefully developed programs to suit many interests and skill sets. From sound design and audio technology to actuarial science, applied cognitive science and human factors to rhetoric and technical communication, the college offers many unique programs.

     
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