The Associations Between Psychological Distress and Academic Burnout: A Mediation and Moderation Analysis.

Background: Psychological distress is reported to be associated with academic burnout in students while the mediation and moderation effect of resilience and personality are less explored.

Purpose: The current study was designed to estimate the mediating effect of resilience and the moderation effect of personality between psychological distress and academic burnout.

Participants And Methods: A total of 613 students were enrolled from two medical universities between December 2020 and January 2021.

Gold nano-mesh synthesis by continuous-flow X-ray irradiation.

X-ray irradiation has been extensively used in recent years as a fabrication step for nanoparticles and nanoparticle systems. A variant of this technique, continuous-flow X-ray irradiation, has recently been developed, and offers three important advantages: precise control of the irradiation dose, elimination of convection effects in the precursor solution, and suitability for large-scale production. Here, the use of this method to fabricate Au nano-meshes of interest as transparent and flexible electrodes for optoelectronics is reported.

Toxic Effects of Size-tunable Gold Nanoparticles on Caenorhabditis elegans Development and Gene Regulation.

We utilized size-tunable gold nanoparticles (Au NPs) to investigate the toxicogenomic responses of the model organism Caenorhabditis elegans. We demonstrated that the nematode C. elegans can uptake Au NPs coated with or without 11-mercaptoundecanoic acid (MUA), and Au NPs are detectable in worm intestines using X-ray microscopy and confocal optical microscopy.

X-ray irradiation synthesis of PEG-coated Au-Pd nanoparticles.

We demonstrate that the combination of x-ray irradiation and capping by polyethylene glycol (PEG) produces excellent flexibility in controlling the structure of Au-Pd nanoparticles while preserving their catalytic performance. We specifically adopted two different fabrication methods: co-reduction and seed-assisted reduction. In both cases, precursor composition plays an important role in controlling the phases and size of the bimetallic nanoparticles.

Optimization of gold nanoparticle photoluminescence by alkanethiolation.

Surface thiolation affects the size of gold nanoparticles and the presence of visible luminescence under UV stimulation. We explored these phenomena by analysing alkanethiolate coatings with different carbon chain lengths, from 3-mercaptopropionic acid to 16-mercaptohexadecanoic acid, synthesized by intense X-ray irradiation. Photoluminescence is present for the smallest nanoparticles, but its intensity becomes more intense as the carbon chain length increases, achieving a quantum efficiency of 28% with a 16-mercaptohexadecanoic acid coating.

X-ray imaging of tumor growth in live mice by detecting gold-nanoparticle-loaded cells.

We show that sufficient concentrations of gold nanoparticles produced by an original synthesis method in EMT-6 and CT-26 cancer cells make it possible to detect the presence, necrosis and proliferation of such cells after inoculation in live mice. We first demonstrated that the nanoparticles do not interfere with the proliferation process. Then, we observed significant differences in the tumor evolution and the angiogenesis process after shallow and deep inoculation.

Very small photoluminescent gold nanoparticles for multimodality biomedical imaging.

An original synthesis method based on X-ray irradiation produced gold nanoparticles (AuNPs) with two important properties for biomedical research: intense visible photoluminescence and very high accumulation in cancer cells. The nanoparticles, coated with MUA (11-mercaptoundecanoid acid), are very small (1.4 nm diameter); the above two properties are not present for even slightly larger sizes.

Gold nanoparticles as high-resolution X-ray imaging contrast agents for the analysis of tumor-related micro-vasculature.

Background: Angiogenesis is widely investigated in conjunction with cancer development, in particular because of the possibility of early stage detection and of new therapeutic strategies. However, such studies are negatively affected by the limitations of imaging techniques in the detection of microscopic blood vessels (diameter 3-5 μm) grown under angiogenic stress. We report that synchrotron-based X-ray imaging techniques with very high spatial resolution can overcome this obstacle, provided that suitable contrast agents are used.

One-pot tuning of Au nucleation and growth: from nanoclusters to nanoparticles.

We describe a simple and effective method to obtain colloidal surface-functionalized Au nanoparticles. The method is primarily based on irradiation of a gold solution with high-flux X-rays from a synchrotron source in the presence of 11-mercaptoundecanoic acid (MUA). Extensive tests of the products demonstrated high colloidal density as well as excellent stability, shelf life, and biocompatibility.

Imaging the cellular uptake of tiopronin-modified gold nanoparticles.

Well-dispersed gold nanoparticles (NP) coated with tiopronin were synthesized by X-ray irradiation without reducing agents. High-resolution transmission electron microscopy shows that the average core diameters of the NPs can be systematically controlled by adjusting the tiopronin to Au mole ratio in the reaction. Three methods were used to study the NP uptake by cells: quantitative measurements by inductively coupled plasma mass spectrometry, direct imaging with high lateral resolution transmission electron microscopy and transmission X-ray microscopy.

Quantitative analysis of nanoparticle internalization in mammalian cells by high resolution X-ray microscopy.

Background: Quantitative analysis of nanoparticle uptake at the cellular level is critical to nanomedicine procedures. In particular, it is required for a realistic evaluation of their effects. Unfortunately, quantitative measurements of nanoparticle uptake still pose a formidable technical challenge.

One-pot synthesis of AuPt alloyed nanoparticles by intense x-ray irradiation.

We synthesized AuPt alloyed nanoparticles in colloidal solution by a one-pot procedure based on synchrotron x-ray irradiation in the presence of PEG (polyethylene glycol). The exclusive presence of alloyed nanoparticles with fcc structure was confirmed by several different experiments including UV-vis spectroscopy, x-ray diffraction (XRD) and transmission electron microscopy (TEM). The composition of the AuPt alloyed nanoparticles can be varied in a continuous fashion by simply varying the feed ratios of Au and Pt precursors.

Tailored Au nanorods: optimizing functionality, controlling the aspect ratio and increasing biocompatibility.

Monodisperse gold nanorods with high aspect ratio were synthesized by x-ray irradiation. Irradiation was first used to stimulate the creation of seeds. Afterward, nanorod growth was stimulated either by chemical reduction or again by x-ray irradiation.

Enhancement of irradiation effects on cancer cells by cross-linked dextran-coated iron oxide (CLIO) nanoparticles.

We investigated iron oxide nanoparticles with two different surface modifications, dextran coating and cross-linked dextran coating, showing that their different internalization affects their capability to enhance radiation damage to cancer cells. The internalization was monitored with an ultrahigh resolution transmission x-ray microscope (TXM), indicating that the differences in the particle surface charge play an essential role and dominate the particle-cell interaction. We found that dextran-coated iron oxide nanoparticles cannot be internalized by HeLa and EMT-6 cells without being functionalized with amino groups (the cross-linked dextran coating) that modify the surface potential from -18 mV to 13.