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Category: particle physics – Page 494

Versatile building blocks make structures with surprising mechanical properties

Researchers at MIT’s Center for Bits and Atoms have created tiny building blocks that exhibit a variety of unique mechanical properties, such as the ability to produce a twisting motion when squeezed. These subunits could potentially be assembled by tiny robots into a nearly limitless variety of objects with built-in functionality, including vehicles, large industrial parts, or specialized robots that can be repeatedly reassembled in different forms.

The researchers created four different types of these subunits, called voxels (a 3D variation on the pixels of a 2D image). Each voxel type exhibits special properties not found in typical natural materials, and in combination they can be used to make devices that respond to environmental stimuli in predictable ways. Examples might include airplane wings or turbine blades that respond to changes in air pressure or wind speed by changing their overall shape.

The findings, which detail the creation of a family of discrete “mechanical metamaterials,” are described in a paper published today in the journal Science Advances, authored by recent MIT doctoral graduate Benjamin Jenett PhD ’20, Professor Neil Gershenfeld, and four others.

CERN Physicists Find First Evidence for Production of Top Quarks in Nucleus-Nucleus Collisions

New results from the CMS Collaboration at CERN’s Large Hadron Collider demonstrate for the first time that top quarks are produced in nucleus-nucleus collisions. The results open the path to study in a new and unique way the extreme state of matter that is thought to have existed shortly after the Big Bang.

First observed in proton-antiproton collisions at the Tevatron collider 25 years ago, this particle is also a unique and potentially very powerful tool to understand the inner content of nuclear matter.

CCNY team in quantum algorithm breakthrough

Researchers led by City College of New York physicist Pouyan Ghaemi report the development of a quantum algorithm with the potential to study a class of many-electron quantums system using quantum computers. Their paper, entitled “Creating and Manipulating a Laughlin-Type ν=1/3 Fractional Quantum Hall State on a Quantum Computer with Linear Depth Circuits,” appears in the December issue of PRX Quantum, a journal of the American Physical Society.

“Quantum physics is the fundamental theory of nature which leads to formation of molecules and the resulting matter around us,” said Ghaemi, assistant professor in CCNY’s Division of Science. “It is already known that when we have a macroscopic number of quantum particles, such as electrons in the metal, which interact with each other, novel phenomena such as superconductivity emerge.”

However, until now, according to Ghaemi, tools to study systems with large numbers of interacting quantum particles and their novel properties have been extremely limited.

Tripping Over the Mysteries of the Universe: Molecules, Particles and People

Ira Pastor, ideaXme life sciences ambassador and CEO Bioquark interviews Dr. Michelle Francl the Frank B. Mallory Professor of Chemistry, at Bryn Mawr College, and an adjunct scholar of the Vatican Observatory.

Ira Pastor comments:

Today, we have another fascinating guest working at the intersection of cutting edge science and spirituality.

Dr. Michelle Francl is the Frank B. Mallory Professor of Chemistry, at Bryn Mawr College, a distinguished women’s college in the suburbs of Philadephia, as well as an adjunct scholar of the Vatican Observatory.

Dr. Francl has a Ph.D. in chemistry from University of California, Irvine, did her post-doctoral research at Princeton University, and has taught physical chemistry, general chemistry, and mathematical modeling at Bryn Mawr College since 1986. In addition Dr. Francl has research interests in theoretical and computational chemistry, structures of topologically intriguing molecules (molecules with weird shapes), history and sociology of science, and the rhetoric of science.

Dr. Francl is noted for developing new methodologies in computational chemistry, is on a list of the 1,000 most cited chemists, is a member of the editorial board for the Journal of Molecular Graphics and Modelling, is active in the American Chemical Society, and the author of “The Survival Guide for Physical Chemistry”. In 1994, she was awarded the Christian R. and Mary F. Lindback Award by Bryn Mawr College for excellence in teaching.

Continue reading “Tripping Over the Mysteries of the Universe: Molecules, Particles and People” | >

Scientists discover new family of quasiparticles in graphene-based materials

A group of researchers led by Sir Andre Geim and Dr. Alexey Berdyugin at The University of Manchester have discovered and characterized a new family of quasiparticles named ‘Brown-Zak fermions’ in graphene-based superlattices.

The team achieved this breakthrough by aligning the atomic lattice of a layer to that of an insulating boron nitride sheet, dramatically changing the properties of the graphene sheet.

The study follows years of successive advances in graphene-boron nitride superlattices which allowed the observation of a fractal pattern known as the Hofstadter’s butterfly—and today (Friday, November 13) the researchers report another highly surprising behavior of particles in such structures under applied magnetic field.

Physicists Devise a Brilliant Way to Make And Observe Elusive Electron Crystals

In 1934, theoretical physicist Eugene Wigner proposed a new type of crystal.

If the density of negatively charged electrons could be maintained below a certain level, the subatomic particles could be held in a repeating pattern to create a crystal of electrons; this idea came to be known as a Wigner crystal.

The first time a Wigner crystal was experimentally observed was in 1979, when researchers measured an electron-liquid to electron-crystal phase transition using helium; since then, such crystals have been detected numerous times.

Luminescent and Hydrophobic Wood Films as Optical Lighting Materials

Most materials used for optical lighting applications need to produce a uniform illumination and require high mechanical and hydrophobic properties. However, they are rarely eco-friendly. Herein, a bio-based, polymer matrix-free, luminescent, and hydrophobic film with excellent mechanical properties for optical lighting purposes is demonstrated. A template is prepared by turning a wood veneer into porous scaffold from which most of the lignin and half of the hemicelluloses are removed. The infiltration of quantum dots (CdSe/ZnS) into the porous template prior to densification resulted in almost uniform luminescence (isotropic light scattering) and could be extended to various quantum dot particles, generating different light colors. In a subsequent step, the luminescent wood film is coated with hexadecyltrimethoxysilane (HDTMS) via chemical vapor deposition. The presence of the quantum dots coupled with the HDTMS coating renders the film hydrophobic (water contact angle ≈ 140°). This top-down process strongly eliminates lumen cavities and preserves the orientation of the original cellulose fibrils to create luminescent and polymer matrix-free films with high modulus and strength in the direction of fibers. The proposed optical lighting material could be attractive for interior designs (e.g., lamps and laminated cover panels), photonics, and laser devices.

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