Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: materials – Page 273

In 2015 UC Santa Barbara mechanical engineer and materials scientist Jonathan Berger developed an idea that could change the way people think about high-performance structural materials. Two years later, his concept is paying research dividends.

In a letter published in the journal Nature, Berger, with UCSB materials and mechanical engineering professor Robert McMeeking and materials scientist Haydn N. G. Wadley from the University of Virginia, prove that the three-dimensional pyramid-and-cross cell geometry Berger conceived is the first of its kind to achieve the performance predicted by theoretical bounds. Its lightness, strength and versatility, according to Berger, lends itself well to a variety of applications, from buildings to vehicles to packaging and transport.

Called Isomax, the beauty of this solid foam—in this case loosely defined as a combination of a stiff substance and air pockets—lay in the geometry within. Instead of the typical assemblage of bubbles or a honeycomb arrangement, the ordered cells were set apart by walls forming the shapes of pyramids with three sides and a base, and octahedra, reinforced inside with a “cross” of intersecting diagonal walls.

Read more

There is way more coming in BMI.

Researcher Dr. Luan and his interdisciplinary team from the University of Texas at Austin have developed an ultra flexible nanoelectronic thread (NET) that has the potential to offer a new type of the long-term neural implants. Neural probes are used to directly measure or even stimulate electrical activity in specific regions of the brain. However, despite the many advances in the field, issues with biocompatibility have limited the prospects and usefulness of the technology. Conventional probes induce scarring around the implant over time, which in turn increasingly impairs the devices’ ability to measure electrical impulses. This scarring is a result of conventional probes’ width, material, and lack of flexibility.

Due to the micrometer dimensions of the NET and its insulation, the implant doesn’t trigger the development of scar tissue and continues working for months at a time. Publishing in the journal Science Advances, the researchers describe the NET from 7 nm nanoprobes layered together and two to three layers of insulation. The layers together total to about 1 µm in thickness, which grants the probe flexibility that is almost 1000 times greater than conventional probes. This flexibility allows the device to remain in place without hindering the movement of or displacing surrounding tissue.

The probe, though significantly smaller, still records data using the same method as standard neural probes. The recording electrodes are evenly placed on the probe, and the collected electrical impulses are communicated to connected devices through microfabricated connections.

Continue reading “Nano Thread Enables Scientists to Extend Length of Brain Implant Efficacy” | >

And, we just started. Just wait — in the next 6 to 8 months; I will some amazing news to share on QBS and BMI. smile

An explosion of nanotechnology research and development is occurring as newly identified forms of carbon, including graphene, carbon nanotubes and nano-diamonds, pave the way for new products and industries.

This article is sponsored by Flinders University.

Read more

Photoemission spectroscopy has detected two different populations of spin-polarized electrons that are “hidden” within a layered, graphene-like material.

The layers inside certain materials can carry spin-polarized electrons, but this polarization is hidden to measurements that aren’t sufficiently localized. A new study using photoemission spectroscopy has detected the hidden spin polarization in a graphene-like material called molybdenum disulfide (MoS22). Unique to this work is the ability to target specific populations of spin-polarized electrons with circularly polarized light.

Read more

The majority of quantum dot (QD) blinking studies have used a model of switching between two distinct fluorescence intensity levels, “on” and “off”. However, a distinct intermediate intensity level has been identified in some recent reports – a so-called “grey” or “dim” state, which has brought this binary model into question. While this grey state has been proposed to result from the formation of a trion, it is still unclear under which conditions it is present in a QD. By performing shell-dependent blinking studies on CdSe QDs, we report that the populations of the grey state and the on state are strongly dependent on both the shell material and its thickness. We found that adding a ZnS shell did not result in a significant population of the grey state. Using ZnSe as the shell material resulted in a slightly higher population of the grey state, although it was still poorly resolved. However, adding a CdS shell resulted in the population of a grey state, which depended strongly on its thickness up to 5 ML. Interestingly, while the frequency of transitions to and from the grey state showed a very strong dependence on CdS shell thickness, the brightness of and the dwell time in the grey state did not. Moreover, we found that the grey state acts as an on-pathway intermediate state between on and off states, with the thickness of the shell determining the transition probability between them. We also identified two types of blinking behavior in QDs, one that showed long-lived but lower intensity on states and another that showed short-lived but brighter on states that also depended on the shell thickness. Intensity-resolved single QD fluorescence lifetime analysis was used to identify the relationship between the various exciton decay pathways and the resulting intensity levels. We used this data to propose a model in which multiple on, grey and off states exist whose equilibrium populations vary with time that give rise to the various intensity levels of single QDs, and which depends on shell composition and thickness.

View: PDF | PDF w/ Links.

Read more

A NIMS research group led by Masahiro Goto, Distinguished Chief Researcher, Center for Green Research on Energy and Environmental Materials, and Michiko Sasaki, postdoctoral researcher, Center for Materials Research by Information Integration (currently a postdoctoral fellow at the University of Tokyo) discovered that the amount of friction force between organic molecules and a sapphire substrate in a vacuum can be changed repeatedly by starting and stopping laser light irradiation. This discovery could potentially lead to the development of technology enabling the movement of micromachines and other small driving parts to be controlled.

The performance of micromachines—used as moving components in small devices such as acceleration sensors and gyroscopes—is greatly affected by adhesion force (the attractive force between two or more materials that stick to each other). Adhesion force in a micromachine increases the friction force. Since increased friction force seriously impedes the movement of moving components, it is necessary to maintain a low level of adhesion force. In addition, if the level of friction force can be controlled, it may be feasible to control the movement of micromachines, leading to expansion of their use and enhancement of their functions. A great deal of attention was previously drawn to techniques enabling silicon-based materials, a major micromachine material, to be coated with diamond-like carbon, self-assembled monolayers, or fluorine-containing organic films in order to reduce friction force and thereby improve the movement of micromachines.

Read more

For the first time, researchers have synthesised a strange and unstable triangle-shaped molecule called triangulene, which physicists have been chasing for nearly 70 years.

Triangulene is similar to the ‘wonder material’ graphene in that it’s only one-atom-thick. But instead of sheet of carbon atoms, triangulene is made up of six hexagonal carbon molecules joined along their edges to form a triangle — an unusual arrangement that leaves two unpaired electrons unable form a stable bond. No one has ever been able to synthesise the molecule until now.

The elusive molecule was created by a team of researchers from IBM, using a needle-like microscope tip to manipulate individual atoms into the desired format.

Read more