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Category: nanotechnology – Page 79

Based on the differently oriented MAPbBr3 single-crystal wafers, this study presents innovative findings primarily in two aspects. First, utilizing polarization-dependent ultrafast time-resolved spectroscopy, the anisotropic dynamics of photoexcited carriers on the picosecond timescale was first revealed. This discovery provides a deeper understanding of the ultrafast carrier relaxation pathways from the perspective of crystal orientation. It holds significant implications for exploring and expanding the potential of perovskite single crystals in polarization-sensitive and ultrafast optoelectronics applications, such as optical modulators, high-speed light polarization sensors, and ballistic transistors, which require both polarization sensitivity and high-field running capability simultaneously. However, a comprehensive understanding to correlate the observed polarization-dependent dynamics with the crystallographic structures has not been achieved yet due to limitations in current excited-state experimental techniques. Further progress will rely on employing more advanced ultrafast probing techniques, in combination with theoretical simulations, to comprehensively elucidate the observed carrier dynamics behind the underlying excited structure.

Second, by employing femtosecond laser processing, luminescent patterns with a remarkable three-order-of-magnitude PL enhancement on the bulk single crystals were achieved. The observed enhancement can be ultimately attributed to the synergy of three factors: the limited carrier diffusion length, the increase in shallow trap-assisted recombination centers, and the passivation of deep traps within the femtosecond laser-induced tentacle-like microstructures. In addition to offering a convenient top-down strategy for enhancing the photoluminescence intensity of bulk crystals, this study has also provided an in-depth understanding of the luminescence mechanism from multiple spatial (bulk and micro/nanoscale) and temporal (steady and transient-state) dimensions.

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https://youtu.be/tLtbWNi-Cgc?si=3i8BqTCAodSKnpkc

Micro Electro Mechanical Systems (MEMS) are miniature devices that integrate mechanical elements, sensors, actuators, and electronics on a single silicon chip. These systems serve diverse applications, such as accelerometers in smartphones, gyroscopes in navigation systems, and pressure sensors in medical devices. MEMS devices can detect and respond to environmental changes, enabling the creation of smart, responsive technologies. Their small size, low power consumption, and ability to perform various functions make MEMS crucial in fields like telecommunications, healthcare, automotive, and consumer electronics. Learn more about this tiny machines with this video!

#science #technology #microscopic #nanotechnology #robotics #engineering

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In a significant advancement for next-generation semiconductors, a collaborative research team has made groundbreaking discoveries in the field of two-dimensional (2D) semiconductors.

Their findings, published in Nano Letters, shed light on the generation and control of trions, providing valuable insights into the optical properties of these materials.

2D semiconductors, known for their exceptional light characteristics per unit volume with high flexibility due to their atomic layer thickness, hold immense potential for applications in areas such as advanced flexible devices, nano photonics, and solar cells.

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New nanocavities pave the way for enhanced nanoscale lasers and LEDs that could enable faster data transmission using smaller, more energy-efficient devices.

As we transition to a new era in computing, there is a need for new devices that integrate electronic and photonic functionalities at the nanoscale while enhancing the interaction between photons and electrons. In an important step toward fulfilling this need, researchers have developed a new III-V semiconductor nanocavity that confines light at levels below the so-called diffraction limit.

“Nanocavities with ultrasmall mode volumes hold great promise for improving a wide range of photonic devices and technologies, from lasers and LEDs to quantum communication and sensing, while also opening up possibilities in emerging fields such as quantum computing,” said the leading author Meng Xiong from the Technical University of Denmark. “For example, light sources based on these nanocavities could significantly improve communication by enabling faster data transmission and strongly reduced energy consumption.

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There are approximately 425 million people worldwide with diabetes. Approximately 75 million of these inject themselves with insulin daily. Now, they may soon have a new alternative to syringes or insulin pumps. Scientists have found a new way to supply the body with smart insulin.

The new insulin can be eaten by taking a capsule or, even better, within a piece of chocolate.

Inside these are tiny nano-carriers in which the insulin is encapsulated. The particles are 1/10,000th the width of a human hair and so small that you cannot even see them under a normal microscope.

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In the presence of protospacer adjacent motif (PAM), sgRNA accurately leads the Cas9 endonuclease to the target regions, where it causes DNA double strand breaks (DSBs), resulting in site‐specific genomic change. Endogenous DNA repair can take place following the creation of a DSB via two primary genome editing pathways: nonhomologous end joining (NHEJ) or homology‐directed repair (HDR).

By using the biological characteristics of Cas9 targeting specific DNA sequences under the guidance of sgRNA, scientists have further developed gene targeting activation and gene targeting inhibition tools based on dCas9, called CRISPRa and CRISPRi respectively.

In the paper, characteristics of three forms of CRISPR/Cas9 cargos are outlined. Three delivery forms of the CRISPR/Cas9 system are plasmids, mRNA/sgRNA, and ribonucleoprotein (RNP) complexes, each of which has its own advantages and disadvantages.

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A team of Rice University researchers mapped out how flecks of 2D materials move in liquid ⎯ knowledge that could help scientists assemble macroscopic-scale materials with the same useful properties as their 2D counterparts.

“Two-dimensional nanomaterials are extremely thin—only several atoms thick—sheet-shaped materials,” said Utana Umezaki, a Rice graduate student who is a lead author on a study published in ACS Nano. “They behave very differently from materials we’re used to in daily life and can have really useful properties: They can withstand a lot of force, resist high temperatures and so on. To take advantage of these unique properties, we have to find ways to turn them into larger-scale materials like films and fibers.”

In order to maintain their special properties in bulk form, sheets of 2D materials have to be properly aligned ⎯ a process that often occurs in solution phase. Rice researchers focused on graphene, which is made up of , and hexagonal boron nitride, a material with a similar structure to graphene but composed of boron and nitrogen atoms.

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