Heat accumulation and phase transition induction in a VO thin film by a femtosecond pulse-periodic radiation.

The kinetics of optical switching due to the insulator-metal phase transition in a VO thin film is studied experimentally at different laser pulse repetition frequencies (PRFs) in the NIR range and compared with temperature kinetics obtained through the thermal conductance calculations. Two switching processes have been found with characteristic times <2 ms and <15 ms depending on the PRF; the former is explained by the accumulation of metallic domains remaining after a single-pulse phase transition, and the latter is referred to the heat accumulation in the film. Consequently, the dynamics of the microscopic domains is leading in the initiation of phase transition under pulse-periodic conditions compared to the macroscopic heat transfer.

Nonlinear optical properties and ultrafast carrier dynamics of ultrathin ReSe.

Rhenium diselenide (ReSe) has shown great application potential in the field of optical devices because of its excellent optoelectronic properties. In this study, we systematically investigated the nonlinear optical absorption properties of mono- and bi-layer ReSe and the ultrafast carrier dynamics process in the ultraviolet to near-infrared spectral range as the essential foundational groundwork for harnessing the potential of ultrathin ReSe-based optoelectronic devices. We found that ReSe has excellent nonlinear absorption performance and a low saturation absorption intensity that is better than that of many semiconductor materials.

Photoacoustic 2D actuator via femtosecond pulsed laser action on van der Waals interfaces.

Achieving optically controlled nanomachine engineering can satisfy the touch-free and non-invasive demands of optoelectronics, nanotechnology, and biology. Traditional optical manipulations are mainly based on optical and photophoresis forces, and they usually drive particles in gas or liquid environments. However, the development of an optical drive in a non-fluidic environment, such as on a strong van der Waals interface, remains difficult.

Anisotropic luminescence and third-order electric susceptibility of Mg-doped gallium oxide under the half-bandgap edge.

Strong anisotropy of photoluminescence of a (100)-cut β-GaO and a Mg-doped β-GaO single crystals was found in UV and visible spectral range, the bands of which were attributed to different types of transitions in the samples. Green photoluminescence in the Mg-doped sample was enhanced approximately twice. A remarkable enhancement of two-photon absorption and self-focusing in β-GaO after doping was revealed by 340-fs laser Z-scanning at 515 nm.

Anisotropic Raman scattering and intense broadband second-harmonic generation in tellurium nanosheets.

Tellurium (Te) is a novel elementary material, which has recently attracted extensive attention due to its intriguing physical properties, such as topological, thermoelectric, and photoelectric properties. Further study on Te crystal structures will help to understand its properties and facilitate its application. Here, the angle-resolved polarized Raman spectroscopy has been employed to study Te crystal symmetry.

Machine Learning Analysis of Raman Spectra of MoS.

Defects introduced during the growth process greatly affect the device performance of two-dimensional (2D) materials. Here we demonstrate the applicability of employing machine-learning-based analysis to distinguish the monolayer continuous film and defect areas of molybdenum disulfide (MoS) using position-dependent information extracted from its Raman spectra. The random forest method can analyze multiple Raman features to identify samples, making up for the problem of not being able to effectively identify by using just one certain variable with high recognition accuracy.

Synthesis and Evaluation of New Trivalent Ligands for Hepatocyte Targeting via the Asialoglycoprotein Receptor.

Since the asialoglycoprotein receptor (also known as the "Ashwell-Morell receptor" or ASGPR) was discovered as the first cellular mammalian lectin, numerous drug delivery systems have been developed and several gene delivery systems associated with multivalent ligands for liver disease targeting are undergoing clinical trials. The success of these systems has facilitated the further study of new ligands with comparable or higher affinity and less synthetic complexity. Herein, we designed two novel trivalent ligands based on the esterification of tris(hydroxymethyl) aminomethane (TRIS) followed by the azide-alkyne Huisgen cycloaddition with azido -acetyl-d-galactosamine.

Photonic-crystal-based broadband graphene saturable absorber.

The enhanced saturable absorption (SA) of a one-dimensional (1D) photonic crystal (PC) made from polymers and graphene composites by spin coating is observed. It shows obvious bandgaps at two wavelengths in transmittance. Femtosecond Z-scan measurement at 515 nm and 1030 nm reveals a distinct enhancement in the effective nonlinear absorption coefficient β for graphene nanoflakes embedded in the PC, when compared with the bulk graphene-polymer composite.

Bacterially synthesized tellurium nanostructures for broadband ultrafast nonlinear optical applications.

Elementary tellurium is currently of great interest as an element with potential promise in nano-technology applications because of the recent discovery regarding its three two-dimensional phases and the existence of Weyl nodes around its Femi level. Here, we report on the unique nano-photonic properties of elemental tellurium particles [Te(0)], as harvest from a culture of a tellurium-oxyanion respiring bacteria. The bacterially-formed nano-crystals prove effective in the photonic applications tested compared to the chemically-formed nano-materials, suggesting a unique and environmentally friendly route of synthesis.

Enhanced two-photon absorption and two-photon luminescence in monolayer MoS and WS by defect repairing.

In this work, we investigated the nonlinear optical properties of monolayer MoS and WS modulated by defect engineering via chemical treatment. The results demonstrate that the two-photon luminescence (TPL) and two-photon absorption (TPA) coefficient were remarkably improved after the repair of sulfur vacancies for both monolayer MoS and WS. After the chemical treatment, the nonradiative relaxation path dominant in pristine monolayer MoS is significantly alleviated, resulting in enhanced TPL.

Competition between stimulated Brillouin scattering and two-photon absorption in dispersed boron nitride.

The design of transparent optical materials with stimulated Brillouin scattering (SBS) suppression is a topic of current interest. We measured two-photon absorption (2PA) cross-section σ and Brillouin gain factor g of a suspension of hexagonal boron nitride (hBN) in N-methyl-2-pyrrolidone at the second harmonic of a Nd:YAG laser. SBS exhibits a significant quenching with hBN concentration, like previously observed in graphene suspension.

Stimulated Brillouin scattering in dispersed graphene.

We explored the Stimulated Brillouin scattering (SBS) behavior of a transparent liquid containing a low concentration of strongly absorbing nanoparticles. We measured SBS energies in N-methyl-2-pyrrolidone (NMP) and water at 532 nm-wavelength. The previously unknown NMP Brillouin gain factor is g = 18.

Mouse lymphomyeloid cells can function with significantly decreased expression levels of cytochrome C.

Cytochrome c is an indispensable electron carrier in the mitochondrial respiratory chain and also an important mediator of the internal pathway triggering apoptosis. Mice with a complete deficiency of the Cycs gene encoding the somatic cytochrome c die during the embryogenesis. Using the technology of LoxP-cre-dependent tissue-specific recombination, we obtained some mouse strains with significantly reduced expression of cytochrome c in certain cell types ("conditional genetic knockdown").

Photodynamic inactivation of enveloped virus in protein plasma preparations by solid-phase fullerene-based photosensitizer.

Background: The problem of transfusion-transmitted infections still remains serious and actual for health care despite the detailed testing of donors. Human immunodeficiency virus, hepatitis B and C viruses and human cytomegalovirus are among the most dangerous pathogens that can be transmitted with blood. Previously, a composition consisting of fullerene layer applied on silica gel particles was shown to inactivate influenza virus up to complete loss of infectivity.