Search Results (361)

Isosorbide-based polycarbonate (PIC) shows promising applications in medical devices and food packaging, owing to its excellent thermal stability, biosafety, optical properties, and scratch resistance. However, trace impurities, especially formic acid in isosorbide (ISB), can significantly influence the performance of PIC. Crude ISB was purified via ion exchange resin. Furthermore, the chromatographic parameters and the adsorption kinetics of formic acid were investigated. The results show that adsorption of formic acid follows the pseudo-second-order kinetic model, suggesting that it is chemisorption. The performance of PIC synthesized from purified ISB has been improved significantly, exhibiting number-average molecular weight (M_n) of 53.9 kg/mol, elongation at break of 10.2%, and Young’s modulus of 1.84 GPa, along with notably enhanced thermal and optical properties. Full article

This work introduces a tunable technique to push the low-frequency corner ($f_L$) of capacitively coupled instrumentation amplifiers (CCIAs) to the sub-mHz range for emerging biosensing applications. The proposed approach combines Complementary Transimpedance Boosting (CTB) to limit the DC feedback current and segmented duty-cycled resistors (SDR) for tunable resistance. The CTB-SDR technique achieves a stable effective post-layout pseudo-resistance of $535.8 \mathrm{T}\Omega$, equivalent to $f_L=660 \mu \mathrm{Hz}$ while occupying $0.062 {\mathrm{mm}}^2$ in a 180 nm process. According to JESD91 standards, it shows a standard deviation of $0.19 \mathrm{mHz}$ under post-layout Monte Carlo + process analysis, $1.1\%$ spread under voltage variations $(\pm 5.56\% V_{DD})$ and $6.2\%$ under temperature variations $(-20 °\mathrm{C}, 27 °\mathrm{C},$ and $60 °\mathrm{C})$. In addition, duty-cycling calibration can compensate for worst-case process corner variations and mismatch-induced feedback instability. Full article

This work reports the electrochemical behavior of a nickel hydroxide electrode, electrodeposited in a deep eutectic solvent (DES), in alkaline solutions of varying composition, aiming to elucidate the influence of the cation (Na⁺ vs. K⁺), urea, and carbonate ions on the mechanism and kinetics of anodic processes. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to analyze the electrochemical responses of electrode processes in alkaline water electrolysis systems. For the urea oxidation reaction (UOR), the frequency-dependent characteristics were thoroughly characterized, and the impedance response was simulated according to the Armstrong–Henderson equivalent circuit. It was found that the addition of urea significantly transforms the impedance structure, sharply reducing the polarization resistance and increasing the pseudo-capacitive component of the constant phase element at low frequencies, indicating activation of the slow steps of urea oxidation via a direct mechanism and the formation of an extended adsorptive surface. It was demonstrated that, unlike conventional alkaline electrolysis where KOH-based systems are generally more effective, urea-assisted systems exhibit superior performance in NaOH-based electrolytes, which provides more favorable kinetics for the electrocatalytic urea oxidation process. Furthermore, the accumulation of carbonate ions was shown to negatively affect UOR kinetics by increasing polarization resistance and partially blocking surface sites, highlighting the necessity of controlling electrolyte composition in practical systems. These findings open new opportunities for the rational design of efficient urea-assisted electrolyzers for green hydrogen generation. Full article

Memristor is widely used to construct various memristive neural networks with complex dynamical behaviors. However, hidden multiple attractors have never been realized in memristive neural networks. This paper proposes a novel chaotic system based on a memristive Hopfield neural network (HNN) capable of generating hidden multiple attractors. A multi-segment memristor model with multistability is designed and serves as the core component in constructing the memristive Hopfield neural network. Dynamical analysis reveals that the proposed network exhibits various complex behaviors, including hidden multiple attractors and a super multi-stable phenomenon characterized by the coexistence of infinitely many double-chaotic attractors—these dynamical features are reported for the first time in the literature. This encryption process consists of three key steps. Firstly, the original chaotic sequence undergoes transformation to generate a pseudo-random keystream immediately. Subsequently, based on this keystream, a global permutation operation is performed on the image pixels. Then, their positions are disrupted through a permutation process. Finally, bit-level diffusion is applied using an Exclusive OR(XOR) operation. Relevant research shows that these phenomena indicate a high sensitivity to key changes and a high entropy level in the information system. The strong resistance to various attacks further proves the effectiveness of this design. Full article

Antibiotic residues such as ciprofloxacin in aquatic systems contribute to antimicrobial resistance and environmental contamination. Conventional treatment processes are often insufficient for removing pharmaceutical contaminants. In this study, activated carbon synthesized from coconut husk using orthophosphoric acid was evaluated for ciprofloxacin adsorption through equilibrium, kinetic, and thermodynamic analyses. The adsorption capacities were 42.34 mg/g for commercial activated carbon (AC) and 36.72 mg/g for synthesized coconut husk activated carbon (CHAC), at an initial ciprofloxacin concentration of 50 mg/L, achieving 85% and 73% removal, respectively. The experimental data obtained were analyzed using five isotherm models (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips). The Sips isotherm better describes AC sorption data than the Freundlich isotherm model for the CHAC, indicating heterogeneous surface coverage. The kinetic model investigation showed a better fit with the Elovich model for AC and the pseudo-second-order model for CHAC, as indicated by higher R² values and lower sum-of-squares errors. Thermodynamic parameters indicated spontaneous and exothermic processes, while SEM analysis confirmed surface porosity and heterogeneity. The results demonstrate that the chemically activated coconut husk is an efficient, low-cost, and sustainable material for mitigating pharmaceutical contamination and addressing antimicrobial resistance in water systems. Full article

This study investigates the hydraulic connection of surface karst features within the Northern segment of the Edwards Balcones Fault Zone Aquifer, using a combination of 2D and pseudo-3D Electrical Resistivity Tomography (ERT) at an outcrop near Salado, Texas. The study site features several surface fractures whose hydrological functions are not well understood. Nine ERT profiles and two pseudo-3D models were used to evaluate the connection between surface fractures and subsurface karst conduits. Karst features at the study site were physically evaluated using characteristics such as morphology, which resulted in the identification of three surface fractures (F1, F2, and F3). The ERT results showed several high-resistivity anomalies interpreted as a poorly fractured zone and low-resistivity water-filled conduits within the Edwards Formation. Furthermore, the result reveals that slow hydraulic connectivity exists in F1 and F2; however, F3 presents a low-resistivity zone that extends vertically into the subsurface, which suggests that F3 may serve as a potential recharge feature to the Edwards Aquifer. These findings are corroborated by a water percolation test, as water penetrated more at F3 compared to F1 and F2. This study showed that the combined application of 2D and pseudo-3D ERT can successfully delineate potential recharge pathways in an exposed karst system, thereby constituting a supportive approach providing critical insight into recharge and the vulnerability of karst aquifers to contamination. Full article

As a result of recent seismic events, it has been observed that earthquake-resistant design worldwide has evolved to the point where structures are generally able to respond adequately to such natural demands. Nevertheless, it has also become evident that nonstructural components and contents anchored to structures have not exhibited equally satisfactory performance. To study the effects of earthquakes on these elements and compare the results with current Chilean code provisions, the present study focuses on determining the maximum absolute floor accelerations in a shear wall building, the most common structural typology in Chilean residential construction. The structure was subjected to destructive seismic excitations representative of the earthquakes that struck Chile in 2010, 2015, and 2017. Based on the obtained accelerations, the demands on nonstructural elements were critically assessed using the current Chilean seismic design code. In this context, the nonlinear behavior of the supporting structure was considered with a damping ratio of 5%. Through time history simulations, floor acceleration records were generated, from which pseudo-accelerations were calculated. Finally, by applying an innovative procedure developed in this study, floor acceleration amplification factors were determined, as well as acceleration spectra intended to guide a more adequate design of nonstructural components. Full article

Through research on the effects of soil and meteorological factors on poplar wood properties, poplar clones with enhanced cold tolerance, drought resistance, and salt–alkali tolerance were selected for large-scale cultivation in the Western Songnen Plain, Northern China. We evaluated wood physical properties (basic density) and anatomical characteristics (annual ring width—RW, vessel number—CNO, vessel lumen area—LA) of 15-year-old Populus simonii × P. nigra, Populus alba × P. berolinensis, P. euramericana N3016 × P. ussuriensis, and Populus pseudo-cathayana × P. deltodides clones in the typical black soil area and saline–alkali land. The results showed that black soil region was more suitable for poplar growth, which was influenced by both soil and meteorological factors. Among soil factors, pH was the primary factor influencing the radial growth of poplar clones, exhibiting a negative correlation for all clones except P. alba × P. berolinensis. Furthermore, P. euramericana N3016 × P. ussuriensis was affected by organic carbon, while P. simonii × P. nigra and P. alba × P. berolinensis were more influenced by potassium. Among climatic factors, basic wood density, annual ring characteristics, and vessel structural parameters in all clones were primarily influenced by wind speed and sunshine, with air temperature having the least effect. Among the four clones, P. alba × P. berolinensis displayed better growth performance (higher RW) and basic wood density (0.29–0.41 g/cm³) at both sites, while P. simonii × P. nigra proved suitable for cold regions. Both clones showing dual adaptability to saline–alkali and black soil environments in Northeast China. Full article

To address the security of digital images, this paper proposes a novel image encryption algorithm based on a six-dimensional memristive chaotic system. First, the algorithm uses the Secure Hash Algorithm 256 (SHA-256) to generate a hash value, from which the initial dynamic key is derived. Next, it integrates Zigzag scrambling, chaotic index scrambling, and diffusion operations to form an encryption scheme with multiple rounds of scrambling and diffusion. In this framework, after each encryption operation, a part of the dynamic key is changed according to the input parameters, and the six-dimensional memristive chaotic system continues iterating to generate the pseudo-random sequence for the next operation. Finally, the proposed algorithm is evaluated using indicators including information entropy, histograms, the Number of Pixels Change Rate (NPCR) and Unified Average Changing Intensity (UACI), encryption time, and so on. The results show that the information entropy of the encrypted image reaches 7.9979; its Chi-square statistic is 186.6875; the average NPCR and UACI are 99.6111% and 33.4643%, respectively; and the encryption time is 0.342 s for the 256 × 256 Cameraman image. These indicate that image encryption is not only effective in encrypting images but also resistant to many conventional attacks. Full article

This review paper presents a comprehensive literature analysis that elucidates the global engagement of research teams in addressing the important problem of finding effective oncology drugs based on the following platinum group metal ions: ruthenium, rhodium and iridium. The necessity to search for new drugs can be attributed, in part, to the predominance of platinum-based chemotherapeutics in clinical practice. However, these drugs face limitations in their clinical application due to their inherent toxicity and the development of resistance by cancer cells. A distinctive attribute of these metal compounds is the formation of diamagnetic stable complexes on +II (Ru) and +III (Rh, Ir) oxidation degrees with a d⁶ electron configuration, a coordination number of six and an octahedral or pseudo-octahedral structure. In this paper we have systematised the findings presented in the literature by classifying the most significant categories of ruthenium, rhodium and iridium compounds, namely piano-stool-type arenes, polypyridine and cyclometalated complexes, dimers and multinuclear complexes. Additionally, the most crucial research challenges connected with metal complexes that have been addressed by scientists have been presented: (i) the application of prodrugs in cancer therapy; (ii) the deployment of complexes as sensitizers in PDT and PACT; (iii) the exploration of complexes as inhibitors of enzymes and biocatalysts; and (iv) the investigation of multiple-target complexes. Furthermore, the objective was to emphasise the accomplishments in this domain in recent years by identifying compounds that have entered the clinical trial phase. Full article

A comprehensive understanding of the denitration kinetics of nitrocellulose-based propellants is crucial for optimizing combustion performance and achieving controllable fabrication. However, most existing studies rely on a single kinetic model, which is restricted by formulation composition and grain geometry, limiting their general applicability. In this work, the denitration rate was quantified using the change in explosion heat, introducing an energy-based characterization approach instead of traditional mass-loss measurements. Three kinetic models (the shrinking-core, pseudo-homogeneous, and Avrami models) were employed to identify the rate-controlling step. The shrinking-core model provided the most accurate description of the process. At moderate reagent concentrations (8 wt.% and 12 wt.%) and temperatures (65–75 °C), denitration was primarily reaction-controlled, while at higher temperatures (80 °C), internal diffusion resistance became significant. The apparent activation energy ranged from 69.8 to 73.7 kJ·mol⁻¹, confirming that chemical reaction is the dominant mechanism. This study refines the kinetic understanding of nitrocellulose denitration and provides theoretical guidance for the controlled fabrication of gradient nitrocellulose propellants with tunable progressive-burning behavior. Full article

This study explores, for the first time, the bioaccumulation of americium-241 (²⁴¹Am) by Cupriavidus metallidurans and Ochrobactrum anthropi, two bacterial strains previously investigated mainly for their interactions with other heavy metals and radionuclides. To the best of our knowledge, no prior studies have reported the use of these microorganisms for ²⁴¹Am removal from aqueous solutions. The effects of initial ²⁴¹Am concentration and solution pH on removal performance were evaluated through batch experiments. Kinetic analyses were performed using pseudo-first-order (PFO) and pseudo-second-order (PSO) models, with the PSO model providing a better fit, suggesting chemisorption as the rate-limiting step in the process. Initial ²⁴¹Am concentrations ranged from 75 to 300 Bq mL⁻¹, and both bacterial strains demonstrated comparable maximum bioaccumulation capacities of approximately 1.5 × 10⁻⁸ mmol g⁻¹. However, O. anthropi exhibited superior resistance to ²⁴¹Am, maintaining colony growth at activity levels up to 1200 Bq mL⁻¹, compared to a threshold of 400 Bq mL⁻¹ for C. metallidurans. These findings highlight the robustness and efficiency of these bacterial strains—particularly O. anthropic—in removing ²⁴¹Am from liquid radioactive waste, offering promising implications for bioremediation technologies. Full article

The presence of 2-methylisoborneol (2-MIB) in water is a critical global concern due to its low threshold and resistance to conventional processes. In the present study, activated carbon/alginate (AC/alginate) composite beads were synthesized via ionic gelation method for the removal of 2-MIB from aqueous solution. The physicochemical characteristics of the adsorbent were determined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. The effects of contact time, solution pH, initial 2-MIB concentration and adsorbent dose on adsorption were examined. Over 95% of 2-MIB removal was obtained under optimum conditions within 360 min. The adsorption equilibrium was well described by Langmuir (R² = 0.97) and Freundlich (R² = 0.96) models suggesting that 2-MIB adsorption involves both monolayer and multilayer adsorption. Kinetic modeling revealed that the pseudo-first order model showed strong fits to the experimental data, indicating the role of surface adsorption in controlling the rate of adsorption. The adsorbent demonstrated reasonable stability, retaining 59% removal efficiency after four adsorption–desorption cycles, highlighting its potential for repeated application in water treatment. Overall, the AC/alginate composite beads were found to be promising for the effective elimination of 2-MIB from water. Full article

Background/Objectives: Actinobacillus pleuropneumoniae is an important respiratory tract pathogen of swine worldwide. Insertion sequences (ISs) play a major role in the transfer of antimicrobial resistance (AMR) among various porcine respiratory tract pathogens. In this study, three A. pleuropneumoniae genomes were investigated for the presence of a novel IS. Methods: Analysis of the draft genomes of three A. pleuropneumoniae serovar 8 isolates (AP_1, AP_120, AP_123) suggested the presence of a novel IS. A closed whole-genome sequence was generated for strain AP_123 by hybrid assembly of Oxford Nanopore MinION long-reads and Illumina MiSeq short-reads, followed by sequence analysis using standard online tools. Transfer was tested by natural transformation. Antimicrobial susceptibility testing was conducted by broth microdilution following Clinical and Laboratory Standards Institute standards. Results: A novel IS, designated ISApl4, was detected in all three genomes. ISApl4 is 712 bp in size and has a transposase gene (tnp) of 654 bp. Moreover, it has perfect terminal 14-bp inverted repeats and produces 8-bp direct repeats at its integration site. This IS was found in 39 copies in the AP_123 genome, two of which formed the 5,765-bp pseudo-compound transposon Tn7560. This transposon carries four AMR genes: sul2 (sulfonamide resistance), strA-strB (streptomycin resistance), and tet(Y) (tetracycline resistance). RT-PCR confirmed tnp gene expression and horizontal transfer of Tn7560 into A. pleuropneumoniae MIDG2331. Conclusions: This study identified the novel ISApl4 in porcine A. pleuropneumoniae and its association with the novel pseudo-compound transposon Tn7560, which proved to be an active element capable of disseminating multidrug resistance amongst A. pleuropneumoniae. Full article

Pharmaceutical contaminants such as tetracycline pose an increasing threat to aquatic ecosystems and human health as a result of their persistence in water sources and their contribution to antibiotic resistance. This study developed chitosan nanocomposites by incorporating functionalised and nitrogen-doped multi-walled carbon nanotubes (FMWCNTs and NMWCNTs) for the removal of tetracycline pharmaceutical contaminants from water. The composites were characterised with FTIR, SEM, XRD, BET, UV–Vis, and TGA under various conditions (pH, adsorbent dosage, concentration, contact time, and temperature). Optimal tetracycline removal (85%) was achieved with pH 6, 2 g/L adsorbent dose, 10 ppm concentration, and 30 min contact time. The FMWCNT–chitosan composite could be recycled five times with an adsorption loss of only 2%. The FMWCNT–chitosan composite showed the good adsorption efficiency of 82% in the presence of counter ions and 70% in a binary system. The adsorption process followed the Langmuir isotherm (263 mg/g), indicative of monolayer adsorption and pseudo-second-order kinetics. Among the nanocomposites prepared, the FMWCNT–chitosan composite showed the highest performance, removing more than 85% of tetracycline from water samples. Full article