Journal of Science: Advanced Materials and Devices最新文献

Mid-infrared (MIR) circularly polarized emission (CPE) is widely used in molecular sensing, information encryption, target detection, and optical communication. However, the generation and regulation of broadband MIR thermal emission with a large degree of circular polarization (DoCP) is still a major challenge. Here, we design a symmetry-broken chiral plasmonic metasurface consisting of asymmetric spilted-ring resonators (ASRRs) to emit broadband CPE with high purity in the MIR region of 3.4–5 μm. The simulated results show that the DoCPs at the wavelengths of 3.74 μm and 4.27 μm are 0.7 and 0.71, respectively, and the DoCP is higher than 0.5 in the wide wavelength ranges of 3.5–4.83 μm. According to the local Kirchhoff's law, the spin-dependent thermal emission originates from the strong inherent local chirality of the ASRR through the near-field distribution and the local emissivity density. Then, the effects of geometric parameters of meta-unit on the DoCP characteristics are studied in detail, which indicates that the geometric perturbation segments quantified by S result in the CPE regulation. Specifically, the DoCP decreases from 0.71 to 0 as the perturbation factor S increases from 0 to 5. Finally, we numerically demonstrate that the designed chiral plasmonic metasurface has potential applications in infrared circularly polarized light detection.

High-k hafnium oxide (HfO₂) film was prepared by high power impulse magnetron sputtering (HiPIMS). The influences of oxygen supply on the plasma state, film properties and TFT performance were investigated. The films are near-stoichiometric and preferentially (−1 1 1)-orientated. When the oxygen supply increased from 1% to 3%, the excitation/ionization rate of the plasma species increased, leading to higher crystallinity, higher density, and lower oxygen vacancy defect concentration of the film, therefore improving the dielectric properties of the film. When the oxygen supply further increased to 5%, the excitation/ionization rate decreased, thereby leading to lower crystallinity, lower density, and higher oxygen vacancy defect concentration of the film, therefore deteriorating the dielectric properties of the film. The film deposited at 3% oxygen supply exhibited the best dielectric properties with the highest k value of 24 and the highest breakdown-electric field (4.7 MV/cm), which should be attributed to the high crystallinity, high density and low oxygen vacancy defect concentration of the film. Finally, transparent thin film transistors (TFTs) with ITO gate electrode, HfO₂ gate dielectric layer and indium-gallium-zinc oxide channel were fabricated on flexible colorless polyimide substrate at full room temperature by all HiPIMS process. The fixed positive charges and k value of HfO₂ film have significant effects on the TFT performance. The best TFT exhibited good electrical performance, featuring a remarkably low subthreshold swing of 0.13 V/decade. It also exhibited fair stability against bending and gate bias stress.

The lack of effective diagnostic and therapeutic techniques is a crucial cause of the high clinical mortality for malignancy. Notably, self-propelled micro/nanomotors are expected to address the drawbacks of conventional nanoparticles in tumor diagnosis and therapy. The special locomotion property ensures the high efficiency of micro/nanomotors in term of rapid distribution, deep penetration, and targeted delivery. Hence, in this review, the motion mechanism and the controllability of speed and direction of the micro/nanomotors were described, as well as the advantages regarding the enhancement of biological barrier crossing (overcoming blood flow obstacles, tumor microenvironment barriers), targeting delivery and deep penetration in the tumor. The most recent advances in micro/nanomotor contributions were comprehensively summarized to various medical imaging technologies, biosensing techniques, and therapeutic approaches, especially for the combination therapy and integration of diagnosis and treatment based on multifunctional micro/nanomotors. Furthermore, challenges for developing practical micro/nanomotors were discussed along with future directions from the clinicians' perspective, which is promised to speed up the clinical translation process and contribute to efficient tumor diagnosis and therapy.

Acoustic levitators are becoming increasingly common research instrumentation for contact-free, lab-in-a-droplet studies. Recently, levitators that employ multiple, small, ultrasonic transducers have gained popularity, given their low price, temperature and spatial stability, low voltage, and accessibility. Yet, the current state-of-the-art device, TinyLev, presents limitations for certain applications in terms of stability, strength, and compactness. Herein, we developed three new levitators and evaluated the effect of the construction parameters (e.g., distance of opposing arrays, number and arrangement of transducers, etc.) on their performance. The best performing levitator from this work had half the number of transducers, compared to TinyLev, though presented 1.7 and 3.5 times higher levitation capacity along the horizontal and vertical configurations, respectively, and 4.7 and 2.0 times higher horizontal and vertical stability of a levitated object, respectively. Additionally, we present a direct means to evaluate the acoustic radiation net force acting on a deformable object for uniaxial levitators, without the use of a microphone or a schlieren deflectometer for this type of levitators. The theoretical and experimental observations provide insights for adapting the acoustic levitator design for specific applications. Finally, we developed an open-source software which allows the evaluation of the acoustic pressure field generated by customized designs and provides the necessary files for 3D printing the scaffold of the levitator. This study aims to increase accessibility and promote further developments in contact-free experiments.

Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is a soft and conjugated polymer whose conductive properties can be properly tuned through doping with various additives or solvents, preserving its excellent processability. In this work PEDOT:PSS was combined with a cost-effective graphite derivative named Edge Oxidized Graphite (EOG) for developing a nanocomposite with improved electrical conductivity, with respect to the pristine PEDOT:PSS, through an easy and environmentally friendly doping process. Firstly, the EOG powders, produced by a green oxidation process of graphite, were deeply characterized through Fourier transform infrared (FT-IR), Thermogravimetric (TGA), and Wide-angle X-ray scattering (WAXD) analysis, showing that this nanofiller has oxygenated functional groups on the sheet edges. The quality and the stability of the EOG dispersions within PEDOT:PSS were investigated at different carbon-filler concentrations, up to high loading of 25 %wt/V of EOG through rheological analyses, demonstrating pseudo-plastic behavior and excellent long-term stability of the inks due to the absence of inhomogeneities and aggregates over time; in fact, the same inks were tested under the same rheological conditions after 21 days, showing the same viscosity trend for all EOG concentrations (%wt/V). Transmission electron microscopy (TEM) and (Scanning Electron microscopy) SEM investigation of spin-coated samples onto glass substrates were performed to morphologically evaluate the nanocomposites and estimate the average size of the sheets, particularly the mean length of 1.2 μm and an approximated thickness of 26 nm of the EOG sheets dispersed into the polymer matrix (PEDOT:PSS) was determined, while WAXD analysis allowed to identify the average layer number of the EOG sheets, obtaining thus, a direct measurement of the EOG sheets aspect ratio equal to 45. Finally, sheet resistance tests showed that the increasing concentration of EOG leads to a significant improvement in the electrical conductivity of the nanocomposites, from 1.1 S/cm for pristine PEDOT:PSS to 21.9 S/cm for nanocomposites with the highest EOG content (25 %wt/V). This work demonstrates the successful development of nanocomposite based on PEDOT:PSS doped with carbon-based filler synthesized through a green and cost-effective process, promoting their use in the production of bio/electrochemical sensors or optoelectronic devices.

Bone tissue engineering (BTE) is a promising alternative approach to the repair of damaged bone tissue. This study aims to fabricate and characterize scaffolds composed of chitosan (CS), hyaluronic acid (HA), hydroxyapatite (HAp), and a combination of graphite (Gr), graphene oxide (GO), and multi-walled carbon nanotubes (MWCNT) for BTE applications. The Gr and MWCNT were functionalized by acid oxidation, while the GO was synthesized using the improved Hummers' method. The scaffolds were prepared by lyophilization, and the physical, chemical, and biological properties were evaluated. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, mechanical testing, water contact angle, degradation, and biocompatibility assays were used to characterize the scaffolds. The degradation rate was determined using the liquid displacement method. Pores of different sizes were present on the surface of and throughout the scaffold. According to the FTIR results, the scaffolds contained functional groups that promote cell differentiation and proliferation. These scaffolds have compressive strength, Young's modulus, and toughness similar to cancellous bone, with reasonable porosity and controllable degradation rates. Biocompatibility testing confirmed that the scaffolds support cell proliferation and differentiation.

This study investigated the removal of tetracycline and ciprofloxacin antibiotics from an aqueous solution in a batch system using magnetic copper ferrite (CuFe₂O₄) nanoparticles as adsorbents. Next, the effects of important parameters such as concentration, adsorbent dosage, ultrasonication time, and pH were examined on the efficiency of the tetracycline and ciprofloxacin removal process. The optimum conditions of the parameters were determined through the Box-Behnken design (BBD) based on the design of the experiment (DOE). The second-order regression coefficients were estimated following the statistical analysis of the results by analysis of variance (ANOVA). The optimal points were determined accurately by combining the results and drawing a second-order multivariate equation. The optimum conditions were obtained at a concentration of 30 mg L⁻¹, a dosage of 0.021 g, a pH of 7, and an ultrasonication time of 11 min. Under the optimum conditions, the maximum removal efficiency was 96.89% and 99.03% for tetracycline and ciprofloxacin, respectively. The performance of CuFe₂O₄ adsorbent in five consecutive experiments did not show much decline, indicating the reusability and stability of the adsorbent. The study results showed that CuFe₂O₄ adsorbent could remove tetracycline and ciprofloxacin from real water samples by more than 98%.

This study investigates an approach to temperature sensing by integrating Titanium Aluminum Nitride (TiAlN), originally engineered for wear and corrosion applications, as a temperature sensor within a multilayered thin film system. A nitride multilayer system was developed by physical vapor deposition (PVD) using a single four-target magnetron sputtering chamber; intermediate vacuum interruption steps were employed for masking procedures. The multilayer architecture design aimed to provide the sensor layer with mechanical protection and electrical shielding. Structural and electrical characterization of the TiAlN single layer revealed semiconductor behavior and stable electrical resistance up to 750 °C, with minimal signal stabilization requirements. Despite the higher Al content, the TiAlN temperature sensor exhibited a cubic crystal structure characterized by diffuse nanolayers, resulting from a two-fold rotational deposition and target configuration. A detailed examination of the multilayer system cross-section containing the TiAlN sensor was conducted using scanning transmission electron microscopy (STEM). The analysis revealed its columnar morphology with the presence of typical PVD growth defects, including voids and droplets. While the presence of these defects may impact the electrical characteristics of the sensor, the selected experimental conditions effectively maintained the structural integrity of the multilayer system despite the vacuum interruptions caused by masking procedures. Validation experiments confirmed the functionality of the multilayer system for temperature measurements up to 400 °C. The signal acquisition system addressed room temperature resistance variations and low sensitivity (thermistor coefficient ∼100 K), resulting in a measured error of approximately 6%. This study demonstrates promising results of TiAlN as a temperature sensor within a multilayered system, expanding its range of potential applications.

A mild and eco-friendly protocol has been developed for the preparation of kaolin-decorated Au nanoparticles mediated by Ephedra root extract as a green reducing and stabilizing agents without any toxic substrates. Structural features of the prepared Au NPs/Kaolin were assessed through FE-SEM, TEM, and XRD techniques. TEM images show the good deposition of Au NPs over the surface of extract-modified kaolin without aggregation. Towards the medicinal application, its antioxidant efficacy was assessed by the DPPH method, and the corresponding IC₅₀ value was obtained as 104 μg/mL. Cytotoxicity of the nanoformulated bio-composite was ascertained through MTT analysis against human ovarian carcinoma cells, i.e., PA-1 and SK-OV-3. The IC₅₀ in those studies was 250 and 119 μg/mL against PA-1and SK-OV-3 cells, respectively. In the in vivo design, tamoxifen was used to induce the experimental adenomyosis model in mice. After treatment, the thymus, spleen, uterine, and body weights of all animals were measured. Then, inflammatory factor expression and myometrial infiltration were determined by qRT-PCR, ELISA, and histology examination in the uterus. Western blotting, qRT-PCR, and immune histochemical (IHC) staining were applied to analyze the MAPK/ERK signaling pathway protein expression. Au NPs/Kaolin bio-nanocomposite ameliorated the adenomyosis symptoms by raising the thymus and spleen index and decreasing the myometrial infiltration. The raised levels of TNF-α, IL-6, and IL-1β in adenomyosis model mice uterus and serum were also reduced after Au NPs/Kaolin bio-nanocomposite treatment. The adenomyosis amelioration of Au NPs/Kaolin bio-nanocomposite was gained by preventing the MAPK/ERK signaling pathway, including decreasing the expressions of protein and mRNA of p-p38/p38, p-JNK/JNK, and p-ERK/ERK.

The electrical properties of bismuth magnesium tantalate pyrochlore, Bi_3.30Mg_1.88Ta_2.82O_13.88 (BMT) were investigated by both inductor-capacitor-resistor (LCR) and impedance spectroscopy techniques covering a broad temperature range of 10–1073 K and a frequency range of 5 Hz - 1 MHz. At below ∼180 K, BMT pyrochlore exhibited interesting relaxor behaviour that showed high dispersion characteristics in its frequency-temperature dependent dielectric constants, ε′ and dielectric losses, tan δ, respectively. The maximum ε′_max of ∼77 was obtained at the temperature maximum, T_m of 154 K. The frequency-independent ε′ data above 154 K at a fixed frequency of 1 MHz can be well fitted with the Curie-Weiss law and the relaxation features of Bi_3.30Mg_1.88Ta_2.82O_13.88 obeyed the Vogel-Fulcher equation. The dielectric properties of Bi_3.30Mg_1.88Ta_2.82O_13.88 relaxor in the low temperature range of 20–320 K could be satisfactorily modeled with different equivalent circuits. In this perspective, a master circuit consisting of a parallel R-C-CPE element in series with a capacitor was required to accurately fit the low temperature data.