Search Results (32)

Synthetic nanopores were recently demonstrated with memristive and nonlinear voltage-current behaviors, akin to ion channels in a cell membrane. Such ionic devices are considered a promising candidate for the development of brain-inspired neuromorphic computing techniques. In this work, we show the composite behavior of nanopore-array large memristors, formed with different membrane materials, pore sizes, electrolytes, and device arrangements. Anodic aluminum oxide (AAO) membranes with 5 nm and 20 nm diameter pores and track-etched polycarbonate (PCTE) membranes with 10 nm diameter pores are tested and shown to demonstrate memristive and nonlinear behaviors with approximately 10⁷–10¹⁰ pores in parallel when electrolyte concentration across the membranes is asymmetric. Ion diffusion through the large number of channels induces time-dependent electrolyte asymmetry that drives the system through different memristive states. The behaviors of series composite memristors with different configurations are also presented. In addition to helping understand fluidic devices and circuits for neuromorphic computing, the results also shed light on the development of field-assisted ion-selection-membrane filtration techniques as well as the investigations of large neurons and giant synapses. Further work is needed to de-embed parasitic components of the measurement setup to obtain intrinsic large memristor properties. Full article

We developed a novel and portable magnetic nanochannel electrochemical sensor for the sensitive detection of cadmium ions (Cd²⁺), which pose serious risks to food safety and human health. The sensor was fabricated by co-modifying an anodic aluminum oxide (AAO) nanochannel membrane with a composite of glutathione (GSH) and ferric oxide nanoparticles (Fe₃O₄), denoted as GSH@Fe₃O₄. This modified membrane was then integrated with a screen-printed carbon electrode (SPCE) to construct the GSH@Fe₃O₄/GSH@AAO/SPCE sensing platform. The performance of the sensor was evaluated using differential pulse voltammetry (DPV), which demonstrated a strong linear correlation between the peak current response and the concentration of Cd²⁺ in the range of 5–120 μg/L. The calibration equation was I_DPV(μA) = −0.31 + 0.98·C_{Cd²⁺(μg/L)}, with an excellent correlation coefficient (R² = 0.999, n = 3). The calculated limit of detection (LOD) was as low as 0.1 μg/L, indicating the high sensitivity of the system. These results confirm the successful construction of the GSH@Fe₃O₄/GSH@AAO/SPCE portable nanochannel sensor. This innovative sensing platform provides a rapid, sensitive, and user-friendly approach for the on-site monitoring of heavy metal contamination in agricultural products, especially grains. Full article

Mango (Mangifera indica), a nutritionally rich tropical fruit, is significantly impacted by UV-B radiation, which induces oxidative stress and disrupts physiological processes. This study aimed to investigate mango pulp’s molecular and biochemical responses to UV-B stress (96 kJ/mol) from the unripe to mature stages over three consecutive years, with samples collected at 10-day intervals. UV-B stress affected both non-enzymatic parameters, such as maturity index, reactive oxygen species (ROS) levels, membrane permeability, and key enzymatic components of the ascorbate-glutathione (AsA-GSH) cycle. These enzymes included glutathione reductase (GR), gamma-glutamyl transferase (GGT), glutathione S-transferases (GST), glutathione peroxidase (GPX), glucose-6-phosphate dehydrogenase (G6PDH), galactono-1,4-lactone dehydrogenase (GalLDH), ascorbate peroxidase (APX), ascorbate oxidase (AAO), and monodehydroascorbate reductase (MDHAR). Transcriptomic analysis revealed 18 differentially expressed genes (DEGs) related to the AsA-GSH cycle, including MiGR, MiGGT1, MiGGT2, MiGPX1, MiGPX2, MiGST1, MiGST2, MiGST3, MiG6PDH1, MiG6PDH2, MiGalLDH, MiAPX1, MiAPX2, MiAAO1, MiAAO2, MiAAO3, MiAAO4, and MiMDHAR, validated through qRT-PCR. The findings suggest that UV-B stress activates a complex regulatory network in mango pulp to optimize ROS detoxification and conserve antioxidants, offering insights for enhancing the resilience of tropical fruit trees to environmental stressors. Full article

For commercial processes, through-hole AAO membranes are fabricated from high-purity aluminum by chemical etching. However, this method has the disadvantages of using heavy-metal solutions, creating large amounts of material waste, and leading to an irregular pore structure. Through-hole porous alumina membrane fabrication has been widely investigated due to applications in filters, nanomaterial synthesis, and surface-enhanced Raman scattering. There are several means to obtain freestanding through-hole AAO membranes, but a fast, low-cost, and repetitive process to create complete, high-quality membranes has not yet been established. Here, we propose a rapid and efficient method for the multi-detachment of an AAO membrane at room temperature by integrating the one-time potentiostatic (OTP) method and two-step electrochemical polishing. Economical commercial AA1050 was used instead of traditional high-cost high-purity aluminum for AAO membrane fabrication at 25 °C. The OTP method, which is a single-step process, was applied to achieve a high-quality membrane with unimodal pore distribution and diameters between 35 and 40 nm, maintaining a high consistency over five repetitions. To repeatedly detach the AAO membrane, two-step electrochemical polishing was developed to minimize damage on the AA1050 substrate caused by membrane separation. The mechanism for creating AAO membranes using the OTP method can be divided into three major components, including the Joule heating effect, the dissolution of the barrier layer, and stress effects. The stress is attributed to two factors: bubble formation and the difference in the coefficient of thermal expansion between the AAO membrane and the Al substrate. This highly efficient AAO membrane detachment method will facilitate the rapid production and applications of AAO films. Full article

Neurodegenerative disorders cause most physical and mental disabilities, and therefore require effective treatment. The blood–brain barrier (BBB) prevents drug molecules from crossing from the blood to the brain, making brain drug delivery difficult. Implantable devices could provide sustained and regulated medication to solve this problem. Two electrolytes (0.3 M oxalic acid and 0.3 M sulphuric acid) were used to anodise Al₂O₃ nanoporous membranes, followed by a third anodisation in concentrated H₂SO₄ to separate the through-hole membranes from the aluminium substrate. FTIR, AFM, and SEM/EDX were used to characterise the membranes’ structure and morphology. The effects of the anodisation time and electrolyte type on the AAO layer pore density, diameter, interpore distance, and thickness were examined. As a model drug for neurodegenerative disorders, donepezil hydrochloride (DHC) was loaded onto thin alumina nanoporous membranes. The DHC release profiles were characterised at two concentrations using a UV–Vis spectrophotometer. Oxalic acid membranes demonstrated an average pore diameter of 39.6–32.5 nm, which was two times larger than sulphuric acid membranes (22.6–19.7 nm). After increasing the anodisation time from 3 to 5 h, all of the membranes showed a reduction in pore diameter that was stable regardless of the electrolyte type or period. Drug release from oxalic acid-fabricated membranes was controlled and sustained for over 2 weeks. Thus, nanoporous membranes as implantable drug delivery systems could improve neurodegenerative disease treatment. Full article

This study explores the effectiveness of an integrated anaerobic membrane bioreactor (AnMBR) coupled with an anoxic/oxic membrane bioreactor (A/O MBR) for the treatment of natural rubber industry wastewater with high sulfate, ammonia, and complex organic contents. This study was conducted at the lab-scale over a duration of 225 days to thoroughly investigate the efficiency and sustainability of the proposed treatment method. With a hydraulic retention time of 6 days for the total system, COD reductions were over 98%, which reduced the influent from 22,158 ± 2859 mg/L to 118 ± 74 mg/L of the effluent. The system demonstrates average NH₃-N, TN, and total phosphorus (TP) removal efficiencies of 72.9 ± 5.7, 72.8 ± 5.6, and 71.3 ± 9.9, respectively. Despite an average whole biological system removal of 50.6%, the anaerobic reactor eliminated 44.9% of the raw WW sulfate. Analyses of membrane fouling revealed that organic fouling was more pronounced in the anaerobic membrane, whereas aerobic membrane fouling displayed varied profiles due to differential microbial and oxidative activities. Key bacterial genera, such as Desulfobacterota in the anaerobic stage and nitrifiers in the aerobic stage, are identified as instrumental in the biological processes. The microbial profile reveals a shift from methanogenesis to sulfide-driven autotrophic denitrification and sulfammox, with evidence of an active denitrification pathway in anaerobic/anoxic conditions. The system showcases its potential for industrial application, underpinning environmental sustainability through improved wastewater management. Full article

Continuous spring cropping of Qingke (Hordeum viilgare L. var. nudum Hook. f.) results in a reduction in grain yield in the Xizang autonomous region. However, knowledge on the influence of continuous cropping on grain yield caused by reactive oxygen species (ROS)-induced stress remains scarce. A systematic comparison of the antioxidant defensive profile at seedling, tillering, jointing, flowering, and filling stages (T1 to T5) of Qingke was conducted based on a field experiment including 23-year continuous cropping (23y-CC) and control (the first year planted) treatments. The results reveal that the grain yield and superoxide anion (SOA) level under 23y-CC were significantly decreased (by 38.67% and 36.47%), when compared to the control. The hydrogen peroxide content under 23y-CC was 8.69% higher on average than under the control in the early growth stages. The higher ROS level under 23y-CC resulted in membrane lipid peroxidation (LPO) and accumulation of malondialdehyde (MDA) at later stages, with an average increment of 29.67% and 3.77 times higher than that in control plants. Qingke plants accumulated more hydrogen peroxide at early developmental stages due to the partial conversion of SOA by glutathione (GSH) and superoxide dismutase (SOD) and other production pathways, such as the glucose oxidase (GOD) and polyamine oxidase (PAO) pathways. The reduced regeneration ability due to the high oxidized glutathione (GSSG) to GSH ratio resulted in GSH deficiency while the reduction in L-galactono-1,4-lactone dehydrogenase (GalLDH) activity in the AsA biosynthesis pathway, higher enzymatic activities (including ascorbate peroxidase, APX; and ascorbate oxidase, AAO), and lower activities of monodehydroascorbate reductase (MDHAR) all led to a lower AsA content under continuous cropping. The lower antioxidant capacity due to lower contents of antioxidants such as flavonoids and tannins, detected through both physiological measurement and metabolomics analysis, further deteriorated the growth of Qingke through ROS stress under continuous cropping. Our results provide new insights into the manner in which ROS stress regulates grain yield in the context of continuous Qingke cropping. Full article

It is essential to reduce carbon emissions in wastewater treatment plants (WWTPs) to achieve carbon neutrality in society. However, current optimization of WWTPs prioritizes the operation cost index (OCI) and effluent quality index (EQI) over greenhouse gas (GHG) emissions. This study aims to conduct a multi-objective optimization of a WWTP, considering GHG emissions, EQI, and OCI. The anaerobic-anoxic-oxic integrated membrane bioreactor (AAO-MBR) process in an actual WWTP was selected as a typical case, tens of thousands of scenarios with combinations of six operational parameters (dissolved oxygen (DO), external carbon resource (ECR), poly aluminum chloride (PAC), internal reflux ratio (IRR), external reflux ratio (ERR), and sludge discharge (SD)) were simulated by GPS-X software (Hydromantics 8.0.1). It was shown that ECR has the greatest impact on optimization objectives. In the optimal scenario, the main parameters of ATDO, MTDO, IRR, and ERR were 0.1 mg/L, 4 mg/L, 50%, and 100%, respectively. The EQI, OCI, and GHG of the best scenario were 0.046 kg/m³, 0.27 ¥/m³, and 0.51 kgCO₂/m³, which were 2.1%, 72.2%, and 34.6% better than the current situation of the case WWTP, respectively. This study provides an effective method for realizing low-carbon and economical operation of WWTPs. Full article

Much attention has been paid to the surface modification of artificial skin barriers for the treatment of skin tissue damage. Chitosan is one of the natural materials that could be characterized by its biocompatibility. A number of methods for the preparation of chitosan membranes have been described in scientific articles, including solvent casting methods. This study investigates an improved technology to produce chitosan membranes. Thus, chitosan membranes were prepared using a vibration-assisted solvent casting method. First, aqueous acetic acid was used to pretreat chitosan. Then, free-standing chitosan membranes were prepared by solvent casting on nanoporous anodized aluminum oxide (AAO) membrane templates, allowing for the solvent to evaporate. Using finite element methods, a study was obtained showing the influence of chitosan solutions of different concentrations on the fluid flow into nanopores using high-frequency excitation. The height of the nanopillars and the surface area of the chitosan membrane were also evaluated. In this study, the surface area of the chitosan membrane was found to increase by 15, 10 and 6 times compared to the original flat surface area. The newly produced nanopillared chitosan membranes will be applicable in the fabrication of skin barriers due to the longer nanopillars on their surface and the larger surface area. Full article

The purpose of the study was to synthesize and investigate the influence of geometrical structure, magnetism, and cytotoxic activity on core–shell platinum and iron–platinum (Fe/Pt) composite nanowires (NWs) for potential application in targeted chemotherapeutic approaches. The Pt-NWs and Fe/Pt composite NWs were synthesized via template electrodeposition, using anodic aluminum oxide (AAO) membranes. The Fe/Pt composite NWs (Method 1) was synthesized using two electrodeposition steps, allowing for greater control of the diameter of the NW core. The Fe/Pt composite NWs (Method 2) was synthesized by pulsed electrodeposition, using a single electrolytic bath. The properties of the synthesized NWs were assessed by high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, powder X-ray diffraction (XRD), inductively coupled plasma–optical emission spectrometry (ICP-OES), vibrating-sample magnetometry (VSM), and surface charge (zeta potential). A microscopy image analysis of the NWs revealed the presence of high-aspect-ratio NWs with nominal diameters of 40–50 nm and lengths of approximately <4 µm. The obtained powder XRD patterns confirmed the presence of a polycrystalline structure for both Pt NWs and Fe/Pt composite NWs. The potential utility of the synthesized NW nanoplatforms for anticancer activity was investigated using Tera 1 cells and Mouse 3T3 cells. Pt-NWs displayed modest cytotoxic activity against Tera 1 cells, while the Fe/Pt composite NWs (both Methods 1 and 2) demonstrated enhanced cytotoxic activity compared to the Pt-NWs on Tera 1 cells. The Fe/Pt composite NWs (Method 1) displayed ferromagnetic behavior and enhanced cytotoxic activity compared to Pt-NWs on Tera 1 cells, thus providing a sound basis for future magnetically targeted chemotherapeutic applications. Full article

Pharmaceutical plants are an essential source of antibiotics emitted into the aqueous environment. The monitoring of target antibiotics in pharmaceutical plants through various regions is vital to optimize contaminant release. The occurrence, distribution, removal, and ecological risk of 30 kinds of selected antibiotics in 15 pharmaceutical plants in the Pearl River Delta (PRD) were investigated in this study. Lincomycin (LIN) showed the highest concentration (up to 56,258.3 ng/L) in the pharmaceutical plant influents from Zhongshan city. Norfloxacin (NFX) showed a higher detection frequency than other antibiotics. In addition, the spatial distribution of antibiotics in pharmaceutical plants showed significant differences, with higher concentrations of total antibiotics found in pharmaceutical plant influents in Shenzhen City than those of different regions in PRD. The treatment processes adopted by pharmaceutical plants were commonly ineffective in removing antibiotics, with only 26.7% of antibiotics being effectively removed (average removal greater than 70%), while 55.6% of antibiotics had removal rates of below 60%. The anaerobic/anoxic/oxic (AAO)-membrane bioreactor (MBR) combined process exhibited better treatment performance than the single treatment process. Sulfamethoxazole (SMX), ofloxacin (OFL), erythromycin-H₂O (ETM-H₂O), sulfadiazine (SDZ), sulfamethazine (SMZ), norfloxacin (NFX), and ciprofloxacin (CIP) in pharmaceutical plant effluents posed high or moderate ecological risk and deserve particular attention. Full article

In the process of sewage treatment, the characteristics of dissolved organic matter (DOM) are always changed during chemical and biological processes, affecting the generation of disinfection by-products (DBPs) compositions at the following disinfection stage. The present study systematically investigated the effect of DOM characterization on C- and N-DBPs formation at AAO-MBR reactor when treating wastewater. The results showed that the AAO-MBR treatment process could efficiently eliminate dissolved organic carbon (DOC) and ammonium nitrogen (NH₄⁺-N) from wastewater with an elimination rate of 89% and 98%, respectively. Most of the precursors (i.e., 56.8% C-DBPs and 78.1% N-DBPs) were removed at the MBR unit, while AGC and AAO units promoted the formation of DBPs precursors. More specifically, soluble microbial products (SMPs) and humus acid were increased, which led to improved C- and N-DBPs via aerated grit chamber (AGC) treatment. At the AAO treatment unit, the content of low MW hydrophobic SMPs, humus acid, and polysaccharides was increased, indicating low MW and HPO fractions dominating the C- and N-DBPs. MBR treatment improved C-DBPs in high MW and HPO fractions and N-DBPs in low MW and HPO fractions, which is explained by higher MW hydrophobic SMPs and humus acids, compared to the AAO unit. The present study provided deep insight into the linkage of DOM characteristics and C- and N-DBPs formation at each treatment unit during the AAO-MBR process. Full article

Diamond nanostructures are mostly produced from bulk diamond (single- or polycrystalline) by using time-consuming and/or costly subtractive manufacturing methods. In this study, we report the bottom-up synthesis of ordered diamond nanopillar arrays by using porous anodic aluminium oxide (AAO). Commercial ultrathin AAO membranes were adopted as the growth template in a straightforward, three-step fabrication process involving chemical vapor deposition (CVD) and the transfer and removal of the alumina foils. Two types of AAO membranes with distinct nominal pore size were employed and transferred onto the nucleation side of CVD diamond sheets. Subsequently, diamond nanopillars were grown directly on these sheets. After removal of the AAO template by chemical etching, ordered arrays of submicron and nanoscale diamond pillars with ~325 nm and ~85 nm diameters were successfully released. Full article

In recent years, many research achievements in the field of anodic aluminum oxide (AAO) membranes can be observed. Nevertheless, it is still an interesting research topic due to its high versatility and applications in various fields, such as template-assisted methods, filtration, sensors, etc. Nowadays, miniaturization is an integral part of different technologies; therefore, research on micro- and nanosized elements is relevant in areas such as LEDs and OLEDs, solar cells, etc. To achieve an efficient mixing process of fluid flow in straight nanopores, acoustofluidic physics has attracted great interest in recent decades. Unfortunately, the renewal of the electrolyte concentration at the bottom of a pore is limited. Thus, excitation is used to improve fluid mixing along nanosized diameters. The effect of excitation by high-frequency vibrations on pore geometry is also investigated. In this study, theoretical simulations were performed. Using theoretical calculations, the acoustic pressure, acoustic velocity, and velocity magnitude were obtained at frequencies of 2, 20, and 40 kHz. Moreover, nanoporous AAO membranes were synthesized, and the influence of high-frequency vibrations on the geometry of the pores was determined. Using a high-frequency excitation of 20 kHz, the thickness of the AAO membrane increased by 17.8%. In addition, the thickness increased by 31.1% at 40 kHz and 33.3% at the resonant frequency of 40 kHz. Using high-frequency vibrations during the anodization process, the electrolyte inside the pores is mixed, and as a result, a higher oxide growth rate and a deeper structure can be achieved. On the other hand, to obtain pores of the same depth, the reaction can be performed in a shorter time. Full article

Nanoporous anodic aluminum oxide (AAO) is needed for a variety of purposes due to its unique properties, including high hardness, thermal stability, large surface area, and light weight. Nevertheless, the use of AAO in different applications is limited because of its brittleness. A new design of an electrochemical reactor with a vibrating element for AAO nanoporous membranes fabrication is proposed. The vibrating element in the form of a piezoceramic ring was installed inside the developed reactor, which allows to create a high-frequency excitation. Furthermore, mixing and vibration simulations in the novel reactor were carried out using ANSYS 17 and COMSOL Multiphysics 5.4 software, respectively. By theoretical calculations, the possibility to excite the vibrations of five resonant modes at different frequencies in the AAO membrane was shown. The theoretical results were experimentally confirmed. Five vibration modes at close to the theoretical frequencies were obtained in the novel reactor. Moreover, nanoporous AAO membranes were synthesized. The novel aluminum anodization technology results in AAO membranes with 82.6 ± 10 nm pore diameters and 43% porosity at 3.1 kHz frequency excitation and AAO membranes with 86.1 ± 10 nm pore diameters and 46% porosity at 4.1 kHz frequency excitation. Furthermore, the chemical composition of the membrane remained unchanged, and the hardness decreased. Nanoporous AAO has become less brittle but hard enough to be used for template synthesis. Full article