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Noise in an electronic circuit is a nuisance that can scramble information or reduce a detector’s sensitivity. But noise also offers a way to learn about the microscopic quantum mechanisms at play in a material or device. By measuring a circuit’s “shot noise,” a form of white noise, researchers have previously shed light on conduction in quantum Hall and spintronic systems, for instance. Now, a collaboration led by Oren Tal at the Weizmann Institute of Science, Israel, and by Dvira Segal at the University of Toronto, Canada, has shown that an easier-to-measure form of noise, called “flicker noise,” can also be a powerful probe of quantum effects [1].

Continue reading “Pink Noise as a Probe of Quantum Transport” »

Whatever you are doing, whether it is driving a car, going for a jog, or even at your laziest, eating chips and watching TV on the couch, there is an entire suite of molecular machinery inside each of your cells hard at work. That machinery, far too small to see with the naked eye or even with many microscopes, creates energy for the cell, manufactures its proteins, makes copies of its DNA, and much more.

Among those pieces of machinery, and one of the most complex, is something known as the nuclear pore complex (NPC). The NPC, which is made of more than 1,000 individual proteins, is an incredibly discriminating gatekeeper for the cell’s nucleus, the membrane-bound region inside a cell that holds that cell’s genetic material. Anything going in or out of the nucleus has to pass through the NPC on its way.

Nuclear pores stud the surface of the cell’s nucleus, controlling what flows in and out of it. (Image: Valerie Altounian)

Solving the 3D structure at near atomic level resolution, one of the world’s hardest, giant jigsaw puzzles—the nuclear pore complex—the largest molecular machine in human cells, with structure-based AI prediction @ScienceMagazine

Researchers at the University of Liverpool have captured a clear view of the generation process of “protein machinery” that plays a key role in the colonization of pathogenic Salmonella bacteria.

The findings, published in Nature Communications, answer an important question about how various proteins self-assemble to create a higher-ordered functional organelle in Salmonella to boost metabolism.

Many pathogenic bacteria, such as Salmonella, use specialized nano-sized organelles, or bacterial microcompartments (BMC). The BMC has a virus-like polyhedral shell made of proteins to encase multiple metabolic cargo enzymes. The protein shell provides a selectively permeable barrier which controls the passage of metabolites and sequesters the reactions in its interior. This ensures higher efficiency of the encapsulated reactions and prevents toxic products from being released into the rest of the cell, providing the pathogens a competitive advantage in human gut.

As people across the globe look forward to longer life expectancies, malignant cancers continue to pose threats to human health. The exploration and development of immunotherapy aims to seek new breakthroughs for the treatment of solid tumors.

The successful establishment of anti-tumor immunity requires the activation, expansion and differentiation of antigen-specific lymphocytes. This process largely depends on specific interactions between various T cells and antigen-presenting cells (APCs) in the body. However, existing tumor vaccines, such as neoantigen vaccines and various vector vaccines, all rely on random interactions with APCs in the body. Furthermore, inappropriate interactions may lead to the silencing of other immune responses.

Although immune checkpoint-based immunotherapy has been shown to have great potential, only a small proportion of patients fully respond to this therapy, and the relevant molecular mechanisms need to be further explored. This delivery method is however complex and inefficient.

One day soon, buildings could become more energy-efficient—and environmentally sustainable—with insulating material developed from wood by researchers in Sweden. The newly-developed material offers as good or even better thermal performance than ordinary plastic-based insulation materials, according to researchers reporting recently in ACS Applied Materials & Interfaces.

Yuanyuan Li, an assistant professor at Wallenberg Wood Science Center, KTH Royal Institute of Technology in Stockholm, says that the new insulating material is an aerogel integrated wood which is made without adding additional substances.

Wood cellulose aerogels themselves are nothing new—researchers have been developing advanced types of aerogels and other composites for the last several years in the Wallenberg Wood Science Center at KTH—but Li says the new method represents a breakthrough in controlled creation of insulating nanostructures in the pores of wood.

Using a network of vibrating nano-strings controlled with light, researchers from AMOLF have made sound waves move in a specific irreversible direction and attenuated or amplified the waves in a controlled manner for the first time. This gives rise to a lasing effect for sound. To their surprise, they discovered new mechanisms, so-called “geometric phases,” with which they can manipulate and transmit sound in systems where that was thought to be impossible. “This opens the way to new types of (meta)materials with properties that we do not yet know from existing materials,” says group leader Ewold Verhagen who, together with shared first authors Javier del Pino and Jesse Slim, publishes the surprising results on June 2 in Nature.

The response of electrons and other charged particles to magnetic fields leads to many unique phenomena in materials. “For a long time, we have wanted to know whether an effect similar to a magnetic field on electrons could be achieved on sound, which has no charge,” says Verhagen. “The influence of a magnetic field on electrons has a wide impact: for example, an electron in a magnetic field cannot move along the same path in the opposite direction. This principle lies at the basis of various exotic phenomena at the nanometer scale, such as the quantum Hall effect and the functioning of topological insulators (materials that conduct current perfectly at their edges and not in their bulk). For many applications, it would be useful if we could achieve the same for vibrations and sound waves and therefore break the symmetry of their propagation, so it is not time-reversal symmetric anymore.”

Aqueous droplet formation by liquid-liquid phase separation (or coacervation) in macromolecules is a hot topic in life sciences research. Of these various macromolecules that form droplets, DNA is quite interesting because it is predictable and programmable, which are qualities useful in nanotechnology. Recently, the programmability of DNA was used to construct and regulate DNA droplets formed by coacervation of sequence designed DNAs.

A group of scientists at Tokyo University of Technology (Tokyo Tech) led by Prof. Masahiro Takinoue has developed a computational DNA droplet with the ability to recognize specific combinations of chemically synthesized microRNAs (miRNAs) that act as biomarkers of tumors. Using these miRNAs as molecular input, the droplets can give a DNA logic computing output through physical DNA droplet phase separation. Prof. Takinoue explains the need for such studies, “The applications of DNA droplets have been reported in cell-inspired microcompartments. Even though biological systems regulate their functions by combining biosensing with molecular logical computation, no literature is available on integration of DNA droplet with molecular computing.” Their findings were published in Advanced Functional Materials.

Developing this DNA droplet required a series of experiments. First, they designed three types of Y-shaped DNA nanostructures called Y-motifs A, B, and C with 3 sticky ends to make A, B, and C DNA droplets. Typically, similar droplets band together automatically while to join dissimilar droplets a special “linker” molecule is required. So, they used linker molecules to join the A droplet with the B and C droplets; these linker molecules were called AB and AC linkers, respectively.

Mimicking the human body, specifically the actuators that control muscle movement, is of immense interest around the globe. In recent years, it has led to many innovations to improve robotics, prosthetic limbs and more, but creating these actuators typically involves complex processes, with expensive and hard-to-find materials.

Researchers at The University of Texas at Austin and Penn State University have created a new type of fiber that can perform like a muscle actuator, in many ways better than other options that exist today. And, most importantly, these muscle-like fibers are simple to make and recycle.

In a new paper published in Nature Nanotechnology (“Nanostructured block copolymer muscles”), the researchers showed that these fibers, which they initially discovered while working on another project, are more efficient, flexible and able to handle increased strain compared to what’s out there today. These fibers could be used in a variety of ways, including medicine and robotics.