We present a simple and fast methodology to realize metal contacts on two-dimensional nanosheets. In particular, we perform a complete characterization of the transport properties of MoS₂ monolayer flakes on SiO₂/Si substrates by using nano-manipulated metallic tips as metallic electrodes directly approached on the flake surface. We report a detailed experimental investigation of transport properties and contact resistance in back-gated field-effect transistor in which the Si substrate is used as the gate electrode. Moreover, profiting from the n-type conduction as well as the high aspect ratio at the edge of the MoS₂ flakes, we also explored the possibility to exploit the material as a field emitter. Indeed, by retracting one of the metallic probes (the anode) from the sample surface, it has been possible to switch on a field emitted current by applying a relatively low external electric field of few tens of Volts for cathode-anode separation distance below 1µm. Experimental data are then analyzed in the framework of Fowler-Nordheim theory and its extension to the two-dimensional limit.

Graphene oxide (GO) is a novel material that can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional optical, chemical, and electrical properties. In this study, GOs with different extent of surface groups were prepared by an electrochemical two-stage approach using graphite as raw material. Various synthesis conditions were tested to increase the nanomaterial oxidation level, and the surface topography of the GO derivatives was analyzed via Scanning Electron Microscopy (SEM) and atomic force microscopy (AFM). The electrochemical approach employed in this study maintains the integrity of the graphene sheets, allowing to get large, uniform and well exfoliated GO. A correlation was found between the derivatives properties and their surface topography, interlayer spacing, defect content and specific surface area (SSA). In particular, the electrical resistance decreases with increasing SSA while rises with increasing the D/G band intensity ratio in the Raman spectra, hence the defect content. Understanding the structure-property relationships in these materials is useful for the design of modified GOs with controlable morphologies and properties for a wide range of applications in electrical/electronic devices.

Mechanoluminescence is a kind of luminescent phenomena that produces photon emission by mechanical stimulation. Benefiting from the characteristics of linear, reusable and nondestructive luminescence, it shows an attractive application prospect in the field of stress distribution detection and attracts more and more attention. However, due to the large size of currently prepared particles, the spatial resolution is around 100 μm. It is necessary to prepare nanoscale particles. However, due to the large specific surface area and high density of surface defects, the luminescent performance of nanoparticles is seriously weakened, limiting their practical applications. On the other hand, the mechanism research of mechanoluminescence is not in-depth enough, which has no guiding significance for material development and performance improvement. Here, we prepared the precursor through hydrothermal synthesis, then annealed the precursor in 1050 °C. By adjusting the doping amount of Pr³⁺, we obtained a kind of high-brightness nanoscale mechanoluminescent material, NaPrNbO₃. This new type of force-induced material is expected to usher in a new era of high resolution strain imaging and contribute to the research of precise dynamic stress/strain imaging of structures.

Tumor normalization strategies aim to improve tumor blood vessel functionality (i.e., perfusion) by restoring tumor vessel compression and hyper-permeability. Despite progress in tumor normalization strategies, their combinatorial antitumor effects with nano- immunotherapy remain unexplored. In this presentation, we re-purposed the TGF-β inhibitor tranilast, an approved anti-fibrotic and antihistamine drug, and combined it with Doxil nanomedicine to normalize murine models of triple negative breast cancer, increase perfusion and oxygenation, and enhance delivery and efficacy of Doxil and immune checkpoint blockers (ICBs). Specifically, we employed two triple-negative breast cancer mouse models to primarily evaluate the therapeutic and normalization effects of tranilast combined with Doxil. We demonstrated the optimized normalization effects of tranilast combined with Doxil and extended our analysis to investigate the effect of tumor normalization to the efficacy of ICBs. Combination of tranilast with Doxil caused a pronounced reduction in extracellular matrix components and an increase in the intratumoral vessel diameter and pericytes coverage, indicators of vessel normalization. These modifications resulted in a significant increase in tumor perfusion and oxygenation and enhanced treatment efficacy as indicated by the notable reduction in tumor size. Furthermore, we found that combining tranilast with Doxil nanomedicine, significantly improved infiltration of T cells into the tumor and the immunostimulatory M1 macrophage content and improved the efficacy of the anti-PD-1/anti-CTLA-4 treatment. We condluded that combinatorial treatment of tranilast with Doxil optimizes tumor normalization towards anti-tumor immunity.

Essential oils (EOs), which are complex biomolecules composed of volatile compounds, have emerged as a new strategy to deal with bacterial infections and as a valid alternative to synthetic drugs. Here, we report the modification of biodegradable wet-spun microfibers composed of cellulose acetate (CA) and polycaprolactone (PCL) with EOs, aiming at their localized, controlled release. Cinnamon leaf oil (CLO), cajeput oil (CJO), and clove oil (CO) were selected from a group of 20 EOs according to their minimal inhibitory concentration (MIC) against Staphylococcus aureus (<22.4 mg/mL) and Escherichia coli (<11.2 mg/mL). CA/PCL prepared at 10% and 14%wt in a 3/1 ratio in acetic acid and acetone were processed in the form of microfibers by wet-spinning at an extrusion rate of 0.5 mL/h directly into an ethanol coagulation bath. Microfibers were modified by immersion in ethanol solutions containing EOs at 2xMIC and ampicillin (control antibiotic). Incorporation was confirmed by UV-VIS, FTIR and TGA. After 72h, fibers contained ampicillin at MIC but only 14%, 66% and 76% of MIC for CLO, CO and CJO, respectively. Unloaded and loaded microfibers were characterized as uniform and homogeneous. Data showed that even at small amounts the EO-modified microfibers were effective against the tested bacteria. Considering the amount immobilized, CLO-containing fibers were deemed the most effective from the group, suggesting a superior affinity of the EOs active groups towards the CA/PCL matrix. These results indicate that CA/PCL microfibers loaded with EOs can be easily produced and applied in scaffolds for biomedical applications.

In this work devices based on a MWCNTs-Si heterojunction were realized growing MWCNTs, by chemical vapour deposition, on an n-type Si substrate with the top and bottom surfaces covered by 140 nm thick Si₃N₄ layers. Two metal contacts, realized on top and back Si surface, were used to perform I-V measurements of the vertical heterostructure. The photocurrent behaviour, obtained by light illumination, was studied as a function of the thickness of MWCNTs layer. A planar quantum efficiency map of the device was obtained by I-V measure when the active area of the device, was rastered by 1 mm diameter light spot. The thickness reduction of the MWCNTs was realized by adhesive tape.

We found that the photocurrent intensity increased when the density of the MWCNTs layer was decreased.

To check the substrate coverage by MWCNTs, scanning electron microscope images was taken.

The main purpose of this study is to develop a sensitive and portable fluorescent sensor system with a fast response time to be used to detect a target analyte. An azo-dye (Basic Red 9) was selected as a model target molecule. The luminescence section of the fluorescent sensor system is composed of UpConverting NanoParticles (UCNP). These luminescent particles were covered by a “recognition element" which is a molecularly imprinted polymer (MIP) shell. MIP shell was synthesized by applying a controlled polymerization technique, namely RAFT polymerization. The MIP covered UCNP core-shell particles (MIP@UCNP) were then covalently attached on the surface of non-woven polyethylene/polypropylene (PE/PP) fabrics via azide-alkyne click coupling reaction. Reusable target molecule-recognizing fluorescent fabrics were therefore prepared. The materials attained in each synthesis step were characterized by TEM, SEM, SEM-EDX, XPS, FTIR and XRD methods. The binding performances were investigated by fluorescence spectroscopy, which yielded a LoD at a few-ppb level. The sensor system developed is (1) more sensitive than similar ones thanks to the well-defined attitude of the MIP shell, (2) user-friendly, portable, practical and low-cost owing to the covalent attachment of nanoparticles on the surface of fabrics.

In this work, high performance conformal Al-doped ZnO (AZO) films are deposited on transparent and flexible muscovite mica substrates by using Atomic Layer Deposition (ALD) technique. AZO/mica films possess high optical transmittance at visible and near-infrared spectral range and retains low electric resistivity, even after continuous bending of up to 800 cycles, confirmed by AFM analysis before and after bending tests. Based on the performed optical and electrical characterizations AZO films are implemented as transparent conductive electrodes in flexible Polymer Dispersed Liquid Crystal (PDLC) smart devices

The manipulation of exciton and biexciton transitions in semiconductor quantum dots using laser pulses is an active research area embodying various theoretical and experimental investigations. Within this context, a problem which has attracted significant attention is the coherent preparation of the biexciton state, when the quantum dot is initially in its ground state. A basic approach employs a linearly-polarized single laser pulse that drives the exciton-biexciton cascade with a two-photon transition between ground and biexciton states. Two frequently used laser pulse shapes are the constant and hyperbolic secant profiles.

In this work, we show that a simple on-off-on pulse-sequence, with pulse durations obtained from the solution of a transcendental equation, can achieve complete preparation of the biexciton state faster than the commonly used constant and hyperbolic secant pulses. Moreover, using numerical optimal control, we demonstrate that for a wide range of values of the maximum pulse amplitude, the proposed pulse-sequence prepares the biexciton state in the minimum possible time, thus provides the quantum speed limit of the system (for fixed maximum control amplitude). We finally show with numerical simulations that, even in the presence of realistic dissipation and dephasing, high levels of biexciton state fidelity can be generated in short times.

Combining soft and hard magnetic materials is not only of technological importance in diverse spintronics elements, but also of high interest in basic research. Here we report on different arrays combining iron and nickel, either in the form of circular nanodots with alternating materials arranged in a regular array, or by embedding circular nanodots of one material in a matrix of the other one. Micromagnetic simulations were performed using the Object Oriented MicroMagnetic Framework (OOMMF). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix in which the nanodots are embedded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Snapshots of the magnetization reversal processes reveal the microscopic processes inside nanodots and magnetic matrix. Such material combinations offer, amongst others, the possibility to prepare quaternary and higher-order memories and are thus highly relevant for applications in data storage and processing.