Journal of Science: Advanced Materials and Devices最新文献

Magnetocaloric microwires are very promising for energy-efficient magnetic refrigeration in micro electromechanical systems (MEMS) and nano electromechanical systems (NEMS). Creating microwires that exhibit large magnetocaloric effects around room temperature represents an important but challenging task. Here, we report a tunable giant magnetocaloric effect around room temperature in Mn_xFe_2-xP_0.5Si_0.5 (0.7≤x ≤ 1.2) microwires by utilizing a melt-extraction technique paired with thermal treatment and chemical engineering. The isothermal magnetic entropy change (ΔS_iso) and Curie temperature (T_C) can be tuned by adjusting the Mn/Fe ratio. The T_C varies from 351 to 190 K as x increases from 0.8 to 1.2. Among the compositions investigated, the x = 0.9 sample shows the largest value of ΔS_iso = 18.3 J kg⁻¹ K⁻¹ for a field change of 5 T around 300 K. After subtracting magnetic hysteresis loss, a large refrigerant capacity of ∼284.6 J kg⁻¹ is achieved. Our study paves a new pathway for the design of novel magnetocaloric microwires for active magnetic refrigeration at ambient temperatures.

Exploration of increased electrode surface area through laser structuring is undertaken to improve performance. While nanosecond lasers offer cost-effective processing, femtosecond lasers achieve a minimal heat effect, excelling in precision. Prior research has mainly focused on changes in electrode performance due to the duration of laser pulses, with insufficient attention to optimizing processability. This study, therefore, aims to compare the processability of active material coating layer in LFP cathodes using both nanosecond and femtosecond lasers. The specimens were subsequently analyzed morphologically for processability using scanning electron microscopy (SEM). Differences in the cross-sectional morphology of LFP cathodes processed by the two types of lasers revealed that nanosecond lasers require a higher pulse energy density for material removal.

Polyphyllin II (PPII) has been proven to have significant anti-liver cancer activity, but its application is limited by poor solubility, low bioavailability, and systemic toxicity caused by non-selectivity. To address the above problem, PPII was encapsulated into the Poly (lactic-co-glycolic acid) (PLGA) by precipitation method (PPII-NPs) for hepatocellular carcinoma treatment. Subsequently, Box–Behnken design (BBD) with three variables-three levels (3³) was utilized to optimize the PPII-NPs formulation. Under optimal conditions, the drug loading of nanoparticles reached 7.29 ± 0.08% and encapsulation efficiency was 80.98 ± 1.63%. Furthermore, aptamer AS1411 was adopted to enhance the tumor-targeting ability of nanoparticles (Apt/PPII-NPs). The drug loading of Apt/PPII-NPs was 6.25 ± 0.26%, had a spherical shape with a rough surface, a particle size of 252.3 ± 3.6 nm, and showed good slow-release performance and stability. In vitro, assays showed that the targeted modified nanoparticles had significant tumor selectivity and exerted efficient anti-tumor effects by inducing tumor cell apoptosis via the mitochondrial apoptotic pathway and death‐receptor pathway. In vivo, anti-tumor evaluation further demonstrated Apt/PPII-NPs not only effectively inhibited the growth of tumors, but also reduced PPII damage to normal tissues. In summary, this report strongly illustrated the advantages of a targeted nanoparticle platform for providing a solution for the rational application of PPII and improving the therapeutic effect of hepatocellular carcinoma.

Cyclodextrins (CDs) are well-known agents in drug delivery systems as they can improve the physical properties of drugs with their distinctive features. Oxymetholone (OXYM) is a derivative of testosterone, a steroid drug that is widely used in the treatment of various diseases. In the current research, the inclusion complexes of OXYM with carboxymethyl-β-cyclodextrin (CM-β-CD/OXYM) and β-cyclodextrin (β-CD/OXYM) have been successfully prepared to improve stability, solubility, and biopharmaceutical profile of OXYM. The characterization of the prepared inclusion complexes was carried out using FT-IR, XRD, TGA, DLS, BET, and UV–Vis techniques. In addition, the morphology of the synthesized inclusion complexes was evaluated in terms of their FE-SEM images. The encapsulation efficiency (EE%), phase solubility, and in vitro drug release of the products were also evaluated using a simple spectrophotometric method. In addition, the kinetic study of in vitro drug release was conducted using the appropriate mathematical equations. In view of the findings of this study, a higher solubility was observed for CM-β-CD/OXYM compared to β-CD/OXYM, nearly three times higher. Furthermore, the in vitro drug release study indicated that β-CD/OXYM offers higher release rates, and the kinetic study demonstrated that both carriers follow a non-Fickian mechanism.

CO₂ methanation is one of the advantageous processes of carbon capture and utilisation (CCU) technologies to circulate the carbon on Earth, mitigating the release and loss of CO₂ into the atmosphere. Herein, a Ni/r-CeO₂ catalyst was fabricated using a facile method of impregnating Ni(NO₃)₂·6H₂O on CeO₂ nanorods (r-CeO₂), synthesised by hydrothermal method at low temperature (130 °C). The influence of Ni active phase content and activation condition on the characteristics and catalytic performances in CO₂ methanation were investigated. The physicochemical properties of the synthesised catalyst were studied using several techniques: XRD, EDS, isotherm nitrogen adsorption, SEM, HR-TEM, H₂-TPR, CO₂-TPD and Raman. Catalytic activity survey and analysis show the excellent performance of Ni/r-CeO₂ with a Ni loading of 15 wt% (15NiCe) calcined at 600 °C for 4 h and reduced at 450 °C for 2.5 h. By adjusting the nickel loading on ceria and altering synthesis conditions, it's possible to achieve highly dispersed NiO particles with an optimal size (∼13.9 nm), abundant oxygen vacancies, and the presence of medium-strength basic sites. This leads to improved catalytic activity, resulting in an equilibrium CO₂ conversion rate of approximately 90% and 100% selectivity for CH₄ at temperatures as low as 325°C. The 15Ni/r-CeO₂ catalyst serves as a highly active low-temperature catalyst for CO₂ methanation.

Significant financial and environmental challenges are associated with using platinum electrodes as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). This work uses rice husk, an agricultural waste, to create active carbon that is appropriate for DSC CEs in response to these difficulties. A simple spray pyrolysis technique created activated carbon obtained from rice husks. The DSC employing activated rice husk carbon as the CE demonstrated a conversion efficiency of 6.06%, slightly lower than the 8.21% efficiency achieved with a platinum electrode-based cell. However, this performance gap is overshadowed by the substantial cost reduction enabled by the utilization of low-cost activated carbon compared to noble metal alternatives. This result introduces promising avenues for investigating the use of agriculturally derived carbon materials as workable and affordable options for platinum CEs in DSCs, thereby contributing to the sustainable advancement of photovoltaic systems. Even though the performance of DSC that uses activated carbon derived from rice husk in CE is slightly lower than its counterparts based on platinum, the cost reduction due to the use of low-cost activated carbon with noble metal is significant.

A compact Ca_xCo_(0.90-x)Zn_0.10Fe₂O₄ based nanoparticles synthesized flexible microwave substrate with single negative (SNG) metamaterial is being successfully fabricated for industrial chemical contamination sensing applications. The unit cell dimensions of the MTM are 0.114λ × 0.114 λ × 0.017 λ. The nanoparticles, derived from the Ca_xCo_(0.90-x)Zn_0.10Fe₂O₄ material with varying Ca concentrations (Ca25, Ca50, and Ca75), have been synthesized using a sol-gel method, and their structural, morphological, and dielectric properties have been comprehensively characterized. Dielectric constants and loss tangents have been measured over the frequency range of 2–20 GHz. Simulation of the S₂₁ response at 3.43 GHz, 6.50 GHz, 11.49 GHz, and 16.46 GHz has yielded maximum magnitudes of −52.78 dB, −48.07 dB, −52.16 dB, and −39.37 dB, respectively. Experimental verification on an FR-4 rigid substrate at 3.28 GHz, 6.58 GHz, 11.76 GHz, and 16.33 GHz has revealed magnitudes of −25.67 dB, −24.56 dB, −31.13 dB, and −25.17 dB. Finally, when fabricated on the flexible microwave substrate, the MTM displayed S21 responses of −48.31 dB, −43.12 dB, −61.80 dB, and −24.70 dB at 3.19 GHz, 6.62 GHz, 11.58 GHz, and 16.65 GHz, respectively. The MTM has exhibited SNG properties in distinct frequency bands and near-zero index (NZI) characteristics. The sensitivity, figure of merit (FOM), and Q-factor have been achieved at 0.096 GHz/RIU, 0.152 GHz/RIU, 0.846 (RIU⁻¹), 0.846 (RIU⁻¹), and 8.430, 29.801, respectively. Its performance has been validated through simulation, VNA measurements, and advanced design system (ADS) software analysis, showcasing promise for diverse applications in S-, C-, X-, and Ku-bands. The anticipated structure performs well in terms of its small size, flexibility, sensitivity, and lightweight, making it suitable for wireless communications and methanol and ethanol contamination sensing in industrial applications.

The electrocatalytic conversion of carbon dioxide (CO₂) into valuable chemicals presents a promising strategy for closing the carbon cycle. In this study, we synthesized zinc (Zn) catalysts through hydrothermal methods using either polyvinylpyrrolidone (PVP) or cetyltrimethylammonium bromide (CTAB) as stabilizing agents. These catalysts proved highly efficient in converting CO₂ into carbon monoxide (CO). Our findings revealed that ZnO, synthesized with different morphologies—namely, nanoneedles (ZnO-NN) and nanorods (ZnO-NR)—underwent significant electro-reconstruction, ultimately leading to the formation of hexagonal metallic Zn crystals, regardless of their initial characteristics. Utilizing ex-situ operando techniques, we elucidated that metallic Zn serves as the active phase for the CO₂-to-CO conversion process. In a comparison, ZnO-NN catalysts demonstrated superior selectivity and stability, achieving 91.3% CO selectivity at a potential of −0.88 V vs. RHE (Reversible Hydrogen Electrode) due to the facile transformation of ZnO to metallic Zn. Remarkably, these catalysts maintained this level of performance for more than 17 h. Conversely, ZnO-NR catalysts exhibited a lower CO selectivity of 62.5% at a relatively higher potential of −0.98 V vs RHE.

The green synthesized Ag/rGO composite nanoparticles were successfully synthesized using the Hummers' method with Amaranthus viridis extract. The localized surface plasmon resonance (LSPR) behavior of the Ag/rGO was studied using the Kretschmann configuration consisting of prism/Au/Ag/rGO/air. The addition of the Ag/rGO composite to the prism system aims to determine the effect of rGO on the SPR angle. X-ray diffraction results showed that there were four diffraction peaks with the presence of lattice planes (111), (200), (220), and (311), proving the face-centered cubic crystal structure of silver. The characterization results showed that the size of Ag NPs was 23.1 nm, and that of Ag/rGO composite was 16.7 nm. The EDX results of the Ag/rGO composite showed the presence of several elements such as C, O, Ag, and N. Fourier transform infrared analysis showed the presence of O–H, C–H, CO, CC, and C–O–C functional groups confirming the formation of Ag/rGO. The UV–Vis spectra showed an absorption peak at 257 nm and 346–412 nm with an increase in band gap energy from 3.27 eV to 3.40 eV. Meanwhile, the LSPR measurements demonstrate a shift in the SPR angle due to the addition of rGO, in which the angle shifts from 0.33 $°$ to 0.96 $°$. In conclusion, the addition of rGO can optimize the plasmonic properties of Ag, so that it potentially could be applied to enhance the performance of SPR-based biosensor applications.

Toxic metals in water systems pose a global health risk. Thus, multifunctional water monitoring and treatment materials are indispensable. Nickel ions, a frequent heavy metal pollutant, affect ecosystem function. However, developing affordable, functional materials for efficient heavy metal removal remains problematic. This study investigates the utilization of Al₂O₃@g-C₃N₄ (AlCN) nanosorbent for adsorbing Ni (II) ions from aqueous solutions. The physicochemical analyses verify the creation of an AlCN nanosorbent with a mean size of 31.25 nm crystals and a specific surface area of 58 m²/g. Batch adsorption experiments were conducted to examine the impact of pH, initial Ni (II) concentration, and adsorbent dose on the efficiency of Ni (II) removal using the synthesized (AlCN) nanosorbent. Adding Al₂O₃ to g-C₃N₄ nanosheets increased the adsorption capacity to a maximum of 410 mg/g under ideal conditions, as demonstrated by the results. Ni (II) ions adsorption kinetics on AlCN nanosorbents follow the pseudo-second-order kinetic model with an R² value of 0.99, surpassing the Elovich pseudo-first model. The adsorption isotherm results show that the Langmuir model fits the experimental data better than the Freundlich and Temkin models, indicating a monolayer adsorption process for the AlCN nanosorbent. In addition, the AlCN exhibited multi-elemental adsorption ability and good recyclability. These findings can nominate the fabricated composite as a candidate for water treatment.