Lifeboat Foundation

Separating densely packed molecules before imaging makes them visible for the first time.

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Continue reading “The Physics of Self-Replication and Nanotechnology” »

Osaka Metropolitan University scientists have developed a simple, rapid method to simultaneously identify multiple food poisoning bacteria, based on color differences in the scattered light by nanometer-scaled organic metal nanohybrid structures (NHs) that bind via antibodies to those bacteria. This method is a promising tool for rapidly detecting bacteria at food manufacturing sites and thereby improving food safety. The findings were published in Analytical Chemistry.

According to the World Health Organization (WHO), every year food poisoning affects 600 million people worldwide—almost 1 in every 10 people—of which 420,000 die. Bacterial tests are conducted to detect food poisoning bacteria at food manufacturing factories, but it takes more than 48 hours to obtain results due to the time required for a bacteria incubation process called culturing. Therefore, there remains a demand for rapid testing methods to eliminate food poisoning accidents.

Responding to this need, the research team led by Professor Hiroshi Shiigi at the Graduate School of Engineering, Osaka Metropolitan University, utilized the optical properties of organic metal NHs—composites consisting of polyaniline particles that encapsulate a large number of metal nanoparticles—to rapidly and simultaneously identify food poisoning-inducing bacteria called enterohemorrhagic Escherichia coli (E. coli O26 and E. coli O157) and Staphylococcus aureus.

Researchers from the University of Pennsylvania demonstrated in a proof-of-concept study that a hands-free device could successfully automate the treatment and removal of dental plaque and bacteria that cause tooth decay.

In the future, a shape-shifting robotic microswarm may serve as a toothbrush, rinse, and dental floss all in one. The technology, created by a multidisciplinary team at the University of Pennsylvania, has the potential to provide a brand-new, automated method for carrying out the repetitive but important daily duties of brushing and flossing. For people who lack the manual dexterity to efficiently clean their teeth alone, this system could be extremely helpful.

These microrobots are composed of iron oxide nanoparticles with catalytic and magnetic properties. Researchers were able to control their movement and configuration using a magnetic field to either produce bristle-like structures that remove dental plaque from the wide surfaces of teeth or elongated threads that can slide between teeth like a piece of floss. In both situations, the nanoparticles are driven by a catalytic reaction to release antimicrobials that eliminate harmful oral bacteria on site.

Researchers looking to synthesize a brighter and more stable nanoparticle for optical applications found that their creation instead exhibited a more surprising property: bursts of superfluorescence that occurred at both room temperature and regular intervals. The work could lead to the development of faster microchips, neurosensors, or materials for use in quantum computing applications, as well as a number of biological studies.

Superfluorescence occurs when atoms within a material synchronize and simultaneously emit a short but intense burst of light. The property is valuable for quantum optical applications, but extremely difficult to achieve at room temperatures and for intervals long enough to be useful.

The material in question—lanthanide-doped upconversion nanoparticle, or UCNP—was synthesized by the research team in an effort to create a “brighter” optical material. They produced hexagonal ceramic crystals ranging from 50 nanometers (nm) to 500 nm in size and began testing their lasing properties, which resulted in several impressive breakthroughs.

Single-wall carbon nanotubes are made of carbon with diameters less than 100 nanometers. Here, the authors engineer an analogue tube with a diameter 1,000,000 times larger with the aim to explore topological properties including unusual acoustic edge states.

A team of researchers at the University of Vienna, the Austrian Academy of Sciences and the University of Duisburg-Essen have found a new mechanism that fundamentally alters the interaction between optically levitated nanoparticles. Their experiment demonstrates previously unattainable levels of control over the coupling in arrays of particles, thereby creating a new platform to study complex physical phenomena. The results are published in this week’s issue of Science.

Imagine dust particles randomly floating around in the room. When a laser is switched on, the particles will experience forces of light and once a particle comes too close it will be trapped in the focus of the beam. This is the basis of Arthur Ashkin’s pioneering Nobel prize work of optical tweezers. When two or more particles are in the vicinity, light can be reflected back and forth between them to form standing waves of light, in which the particles self-align like a crystal of particles bound by light. This phenomenon, also called optical binding, has been known and studied for more than 30 years.

It came as quite a surprise to the researchers in Vienna when they saw a completely different behavior than was expected when studying forces between two glass nanoparticles. Not only could they change the strength and the sign of the binding force, but they could even see one particle, say the left, acting on the other, the right, without the right acting back on the left. What seems like a violation of Newton’s third law (everything that is being acted upon acts back with same strength but opposite sign) is so-called non-reciprocal behavior and occurs in situations in which a system can lose energy to its environment, in this case the laser. Something was obviously missing from our current theory of optical binding.

Cutting intricate patterns as small as several billionths of a meter deep and wide, the focused ion beam (FIB) is an essential tool for deconstructing and imaging tiny industrial parts to ensure they were fabricated correctly. When a beam of ions, typically of the heavy metal gallium, bombards the material to be machined, the ions eject atoms from the surface—a process known as milling—to sculpt the workpiece.

Beyond its traditional uses in the semiconductor industry, the FIB has also become a critical tool for fabricating prototypes of complex three-dimensional devices, ranging from lenses that focus light to conduits that channel fluid. Researchers also use the FIB to dissect biological and material samples to image their internal structure.

However, the FIB process has been limited by a trade-off between high speed and fine resolution. On the one hand, increasing the ion current allows a FIB to cut into the workpiece deeper and faster. On the other hand, the increased current carries a larger number of positively charged ions, which electrically repel each other and defocus the beam. A larger, diffuse beam, which can be about 100 nanometers in diameter or 10 times wider than a typical narrow beam, not only limits the ability to fabricate fine patterns but can also damage the workpiece at the perimeter of the milled region. As a result, the FIB has not been the process of choice for those trying to machine many tiny parts in a hurry.

As the size of modern technology shrinks down to the nanoscale, weird quantum effects—such as quantum tunneling, superposition, and entanglement—become prominent. This opens the door to a new era of quantum technologies, where quantum effects can be exploited. Many everyday technologies make use of feedback control routinely; an important example is the pacemaker, which must monitor the user’s heartbeat and apply electrical signals to control it, only when needed. But physicists do not yet have an equivalent understanding of feedback control at the quantum level. Now, physicists have developed a “master equation” that will help engineers understand feedback at the quantum scale. Their results are published in the journal Physical Review Letters.

“It is vital to investigate how feedback control can be used in quantum technologies in order to develop efficient and fast methods for controlling quantum systems, so that they can be steered in real time and with high precision,” says co-author Björn Annby-Andersson, a quantum physicist at Lund University, in Sweden.

An example of a crucial feedback-control process in quantum computing is quantum error correction. A quantum computer encodes information on physical qubits, which could be photons of light, or atoms, for instance. But the quantum properties of the qubits are fragile, so it is likely that the encoded information will be lost if the qubits are disturbed by vibrations or fluctuating electromagnetic fields. That means that physicists need to be able to detect and correct such errors, for instance by using feedback control. This error correction can be implemented by measuring the state of the qubits and, if a deviation from what is expected is detected, applying feedback to correct it.