Search Results (356)

Free chlorine (FC) plays a crucial role in ensuring the safety of drinking water by effectively inactivating pathogenic microorganisms. However, traditional methods for measuring FC levels often require specialized equipment and laboratory settings, limiting their accessibility and practicality for on-site or point-of-use monitoring. QR Codes are powerful machine-readable patterns that are used worldwide to encode information (i.e., URLs or IDs), but their computer vision features allow QR Codes to act as carriers of other features for several applications. Often, this capability is used for aesthetics, e.g., embedding a logo in the QR Code. In this work, we propose using our technique to build back-compatible Color QR Codes, which can embed dozens of colorimetric references, to assist in the color correction to readout sensors. Specifically, we target two well-known products in the HORECA (hotel/restaurant/café) sector that qualitatively measure chlorine levels in samples of water. The two targeted methods were a BTB strip and a DPD powder. First, the BTB strip was a pH-based indicator distributed by Sensafe^®, which uses the well-known bromothymol blue as a base-reactive indicator; second, the DPD powder was a colorimetric test distributed by Hach^®, which employs diethyl-p-phenylenediamine (DPD) to produce a pink coloration in the presence of free chlorine. Custom Color QR Codes were created for both color palettes and exposed to several illumination conditions, captured with three different mobile devices and tested over different water samples. Results indicate that both methods could be correctly digitized in real-world conditions with our technology, rendering a 88.10% accuracy for the BTB strip measurement, and 84.62% for the DPD powder one. Full article

Vitamins are crucial micro-nutrients for overall well-being, making continuous monitoring essential. There are demands to provide an alternative detection, especially using a portable detection or a point-of-care-testing (POCT) device. One promising approach is employing an in situ electro-polymerised MIP (eMIP), which offers a straightforward polymerisation technique on screen-printed electrodes (SPEs). Here, we report a review based on three databases (PubMed, Scopus, and Web of Science) from 2014 to 2024 using medical subject heading (MeSH) terms “electrochemical polymerisation” OR “electropolymerisation” crossed with the terms “molecularly imprinted polymer” AND “vitamin A” OR “vitamin D” OR “vitamin E” OR “vitamin K” OR “fat soluble vitamin” OR “vitamin B” OR “vitamin C” OR “water soluble vitamin”. The resulting 12 articles covered the detection of vitamins in ascorbic acid, riboflavin, cholecalciferol, calcifediol, and menadione using monomers of catechol (CAT), 3,4-ethylenedioxythiophene (EDOT), o-aminophenol (oAP), o-phenylenediamine (oPD), pyrrole, p-aminophenol (pAP), p-phenylenediamine (pPD), or resorcinol (RES), using common bare electrodes including graphite rod electrode (GRE), glassy carbon electrode (GCE), gold electrode (GE), and screen-printed carbon electrode (SPCE). The most common electrochemical detections were differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV). The imprinting factor (IF) of the eMIP-modified electrodes were from 1.6 to 21.0, whereas the cross-reactivity was from 0.0% to 29.9%. Several types of food and biological samples were tested, such as supplement tablets, poultry and pharmaceutical drugs, soft drinks, beverages, milk, infant formula, human and calf serum, and human plasma. However, more discoveries and development of detection methods needs to be performed, especially for the vitamins that have not been studied yet. This will allow the improvement in the application of eMIPs on portable-based detection and POCT devices. Full article

Designing high-performance crosslinked polymers requires overcoming the inherent stiffness–toughness trade-off through precise control of the network topology. Using epoxy resin as a model system, we establish a multiscale simulation framework to investigate curing reaction kinetics, network evolution, and structure–property relationships. By employing m-phenylenediamine (mPDA) and 1,3-bis(3-aminophenoxy)benzene (DABPB) as competing short- and long-chain curing agents, we demonstrate how network architecture dictates mechanical performance. Simulations reveal that mPDA produces a dense, heterogeneous network with enhanced stiffness, whereas DABPB forms a more uniform structure with greater chain mobility, leading to improved toughness. Through stoichiometric tuning, we achieve fine control over crosslink density and mechanical properties. Furthermore, we decouple cavity formation mechanisms into pendant chain slippage and bond rupture, offering molecular-level insights for the rational design of epoxy resins with programmable mechanical behavior. Full article

A compatibilizer for low-density polyethylene (LDPE)/poly(ethylene terephthalate) (PET) blends was developed. This compatibilizer consists of amine-functionalized PET, which is blended with maleated polyethylene to form a copolymer. The goal is to use this compatibilizer in the future for recycling plastic waste from the marine environment. Fourier-transform infrared spectroscopy confirmed the successful incorporation of amine groups into PET chains through the addition of p-phenylenediamine in a molten state. An increase in diamine content allowed for the visualization of three bands where PET reacted with the diamine. Differential scanning calorimetry suggested that the polyester chains were grafted onto the maleated polyethylene backbone, with crystallinity increasing up to 2.5% diamine content. Scanning electron microscopy (SEM) images showed that the LDPE/PET blend resulted in a continuous polyethylene matrix with a dispersed polyester phase. The blend compatibilized with modified maleated polyethylene, and functionalized PET exhibited an improved interface. Oscillatory rheology and dynamic mechanical analysis indicated that the developed compatibilizer positively impacted the mechanical properties of the compatibilized LDPE/PET blends. This new approach enables the creation of innovative strategies for enhancing the properties of pre-existing polyolefin/polyester recycled blends. Full article

High-strength and high-modulus epoxy resins are key elements for preparing carbon-fiber-reinforced polymer composites, which play an irreplaceable role in aerospace. In this study, five optimal epoxy systems were developed utilizing the reverse design strategy. The reverse design strategy was based on the ideal resin and curing agent structures offered by the AI polymer platform, and the rules were summarized to create an optimum resin formulation. The formulations used m-phenylenediamine (MPD) as the principal curing agent, which was modified with 10 wt% diethyltetramethylenediamine (DETDA), 10 wt% 4,4′-diaminodiphenylmethane (DDM), or 10 wt% triethylenetetramine (TETA) to establish multiple crosslinking networks. Systematic characterization using differential scanning calorimetry (DSC) and rheological analysis revealed that the optimized activation energy was 55.95–63.42 kJ/mol, and the processing viscosity was ≤500 mPa·s at 80 °C. A stepwise curing protocol (3 h@80 °C, 2 h@120 °C, and 3 h@180 °C) was established to achieve a complete crosslinking network. The results showed that the system with 10% DDM had a tensile strength of 132.6 MPa, a modulus of 5.0 GPa, and a glass transition temperature of 253.1 °C. This work advances the rational design of epoxy resins by bridging molecular architecture with macroscopic performance, offering a paradigm for developing a next-generation matrix tailored to accommodate extreme operational demands in high-end engineering sectors. Full article

The urgency of reducing pollution and developing clean energy storage requires efficient photocatalytic hydrogen evolution (PHE) tactics. To improve solar conversion efficiency, it is highly imperative to accelerate the photocarriers separation and transport through materials design. A stable hydrogen evolution photocatalyst based on TpPa-COFs (triformylphloroglucinol phenylenediamine covalent organic frameworks) was developed by a molecular-level design strategy. The study successfully introduced a molecular-scale Ir active site onto the surface of TpPa-COFs via coordination bonds. It verified the structural integrity of TpPa-COFs and the existence of Ir through the basic structural characterizations, such as Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). After the Ir-based coordination compound joining, the absorption edge of TpPa-COF-M1 and TpPa-COF-M2 was extended to 750 nm. The TpPa-COF + M1 exhibited the highest photocatalytic H₂ evolution rate of 662 µmol/h (10 mg catalyst) under visible-light (λ ≥ 420 nm) irradiation. The apparent quantum yield (AQY) of TpPa-COF-M1 is calculated to be 1.9%, 3.8%, 4.8%, 2.8%, 1.8%, and 0.3% at monochromatic wavelengths of 420, 450, 470, 500, 550, and 600 nm, respectively. Our findings confirm that the molecular-level design of photocatalysts can effectively boost performance and reduce cost in photocatalytic reactions and provide an important strategy for designing efficient photocatalysts. Full article

Aqueous zinc-ion batteries (ZIBs) represent an emerging energy storage solution that offers significant advantages in terms of safety, cost-effectiveness, and longevity in cycling. Among the various materials available, manganese-based oxides stand out as the most promising options for cathodes due to their impressive theoretical specific capacity, suitable operating voltage, and abundant natural availability. In published reports, pre-embedding is frequently used to modify the layered cathode; however, non-electrochemically active molecular embedding often results in a decrease in battery capacity. In this paper, a hydrothermal method is employed to intercalate poly(o-phenylenediamine) (PoPD) into δ-MnO₂ (MO) to produce PoPD-MO cathode materials. Here, PoPD serves a dual role in the cathode: (1) PoPD is inserted into the interlayer of MO, providing support within the intercalation layer, enhancing material stability, increasing ionic storage sites, and creating space for more Zn²⁺ to be embedded, and (2) inserting PoPD into the interlayer structure of MO effectively expands the space between layers, thus allowing for greater ion storage, which in turn enhances the rate and efficiency of electrochemical reactions. Consequently, PoPD-MO shows remarkable cycling durability and adaptability in ZIBs, achieving a specific capacity of 359 mAh g⁻¹ at a current density of 0.1 A g⁻¹, and even under the strain of a high current density of 3 A g⁻¹, it maintains a respectable capacity of 107 mAh g⁻¹. Based on this, PoPD-MO may emerge as a new cathode material with promising applications in the future. Full article

Background/Objectives: Patch testing is a valuable clinical tool for identifying the causes of allergic contact dermatitis (ACD). This study aimed to identify common allergens in southern Taiwan. Methods: A retrospective review of patch test data from April 2019 to May 2023 was conducted at a tertiary medical center. The European Baseline Series of allergens was utilized to evaluate and identify the causes of dermatitis. The prevalence rates of contact sensitization to each allergen were calculated. Results: A total of 57 patients (mean age 41.8 years) with contact dermatitis who underwent patch testing were included. The most common allergens were cobalt chloride (24.6%), followed by fragrance mix I (19.3%), Peru balsam (17.5%), nickel (II) sulfate hexahydrate (15.8%), benzisothiazolinone (15.8%), 4-Phenylenediamine (PPD) base (10.5%), and methyldibromo glutaronitrile (10.5%). Patients with positive patch test results frequently had a history of allergic rhinitis (26.3%), atopic dermatitis (24.6%), urticaria (21.1%), and elevated immunoglobulin E (IgE) levels (28.1%). The hairdressing profession was associated with a higher risk of hand eczematous dermatitis. Conclusions: Positive patch test results were observed in 86% of patients diagnosed with contact dermatitis. This study found that cobalt, rather than nickel, was the most prevalent allergen in patients with contact dermatitis. Elevated IgE levels were observed in ACD patients, with the hands being the most frequently affected area. Occupations as accountants, secretaries, and in the hairdressing and cosmetics industries were strongly associated with hand eczematous dermatitis. The early identification of allergens and appropriate treatment strategies significantly reduced recurrence rates and improved outcomes. For individuals with specific allergies, ongoing avoidance of identified allergens is crucial to managing and preventing allergic reactions. Further research is needed to elucidate the mechanisms and responses to novel therapies, including biologic agent- and nanotechnology-based treatments. Full article

N-(1,3-dimethylbutyl)-N’-phenyl-p-benzoquinone (6PPD-Q) is an emerging environmental contaminant that is widely distributed in aquatic environments and presents significant toxicological risks to aquatic organisms. As 6PPD-Q is primarily derived from oxidative transformation of the tire antioxidant N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD), its persistence and potential for bioaccumulation in aquatic organisms have raised widespread concerns. This study reviews the environmental sources, spatial distribution, migration, and transformation behaviors of 6PPD-Q, as well as its degradation mechanisms in different environmental media. Additionally, this review systematically explores the toxicological effects of 6PPD-Q on aquatic organisms, including its physiological, biochemical, and molecular impacts on fish, crustaceans, mollusks, and algae, with a focus on potential toxicological mechanisms. Finally, we discuss the limitations of current research on 6PPD-Q and propose key directions for future studies, including long-term ecological risk assessments, mechanisms of bioaccumulation, metabolic pathway analysis, and optimization of pollution control strategies, aiming to provide a scientific basis for the ecological risk assessment and pollution management of 6PPD-Q. Full article

In this work, a novel molecularly imprinted electrochemical sensor was proposed based on molecular imprinting technology for the detection of sulfamethazine. A glassy carbon electrode was modified with a composite material of carbon nanotubes and graphene quantum dots to effectively improve sensitivity. The molecularly imprinted electrochemical sensor was then prepared by electropolymerization using sulfamethazine as the template and o-phenylenediamine as the functional monomer on the modified electrode. Under optimal measurement conditions, electrochemical tests of different sulfamethazine concentrations (0.5 μM–200 μM) showed excellent linearity and a detection limit of 0.068 μM. In addition, the sensor demonstrated satisfactory selectivity, stability, and reusability. Furthermore, the sensor was applied to the spiked analysis of sulfamethazine in grouper aquaculture water, achieving recovery rates between 95.4% and 104.8%, with a relative standard deviation (RSD) of less than 4.14%. These results indicated that the developed method was effective for the analysis of sulfamethazine in aquaculture seawater, providing a new approach for the detection of antibiotic residues in seawater samples. Full article

A method for the determination of trace selenium in water enriched by metal–organic−framework material (MIL−125−NH₂) and reversed−phase ultra−high−performance liquid chromatography−diode array detection (UPLC−DAD) was established. The MIL−125−NH₂ material, synthesized by the microwave method, was characterized by SEM, XRD, and FT−IR. The MIL−125−NH₂ material was added to the water sample to enrich the selenium, the enriched selenium was desorbed with dilute HCl, and then the derivative reaction with 0.1 mol·L⁻¹ 4−nitro−o−phenylenediamine was performed to produce piaselenole. After extraction with cyclohexane, the retention time and the spectrogram were qualitatively detected by a liquid chromatography−diode array detector, and the peak area was quantitatively detected. The pH, time, amount of material, extractant, and other conditions of derivation and enrichment were optimized in the experiment, and the methodology was verified under optimized conditions. The results showed that the linear correlation coefficient R² was 0.9998, the detection limit of 0.13 μg·L⁻¹ without enrichment was close to that of the ICP−MS method, the detection limit after 10−fold enrichment was 0.013 μg·L⁻¹, the RSD was 0.7~2.7%, and the recovery was 87.8~102.1%, in the range of 2~1000 μg·L⁻¹. Therefore, the method can be applied for the determination of trace selenium in tap water, river water, mountain spring water, packaged drinking water, and industrial sewage. Full article

As a porous crystalline material, covalent organic frameworks (COFs) have attracted significant attention due to their extraordinary features, such as an ordered pore structure and excellent stability. Synthesized through the aldehyde amine condensation reaction, TpPa-1 COFs (Triformylphloroglucinol-p-Phenylenediamine-1 COFs) were blended with cellulose acetate (CA) to form a casting solution. The TpPa-1 COF/CA ultrafiltration membrane was then prepared using the non-solvent-induced phase inversion (NIPS) method. The influence of TpPa-1 COFs content on the hydrophilicity, stability and filtration performance of the modified membrane was studied. Due to the hydrophilic groups in TpPa-1 COFs and the network structure formed by covalent bonds, the modified CA membranes exhibited higher hydrophilicity and lower protein adsorption compared with the pristine CA membrane. The porous crystalline structure of TpPa-1 COFs increased the water permeation path in the CA membrane, improving the permeability of the modified membrane while maintaining an outstanding bovine serum albumin (BSA) rejection. Furthermore, the addition of TpPa-1 COFs reduced protein adsorption on the CA membrane and overcame the trade-off between permeability and selectivity in CA membrane bioseparation applications. This approach provides a sustainable method for enhancing membrane performance while enhancing the application of membranes in protein purification. Full article

The large-scale application of aromatic polyamide (PA) thin-film composite (TFC) membranes for reverse osmosis has provided an effective way to address worldwide water scarcity. However, the water permeability and salt rejection capabilities of the PA membrane remain limited. In this work, cyclic micropores based on crown ether were introduced into the PA layer using a layer-by-layer interfacial polymerization (LbL-IP) method. After interfacial polymerization between m-phenylenediamine (MPD) and trimesoyl chloride (TMC), the di(aminobenzo)-18-crown-6 (DAB18C6) solution in methanol was poured on the membrane to react with the residual TMC. The cyclic micropores of DAB18C6 provided the membrane with rapid water transport channels and improved ion rejection due to its hydrophilicity and size sieving effect. The membranes were characterized by FTIR, XPS, SEM, and AFM. Compared to unmodified membranes, the water contact angle decreased from 54.1° to 31.6° indicating better hydrophilicity. Moreover, the crown ether-modified membrane exhibited both higher permeability and enhanced rejection performance. The permeability of the crown ether-modified membrane was more than ten times higher than unmodified membranes with a rejection above 95% for Na₂SO₄, MgSO₄, MgCl_2, and NaCl solution. These results highlight the potential of this straightforward surface grafting strategy and the modified membranes for advanced water treatment technologies, particularly in addressing seawater desalination challenges. Full article

This research presents a novel, cost-effective, and scalable approach for the direct detection of myoglobin (Myo) in point-of-care (PoC) applications. In this strategy, redox-active Prussian Blue nanocubes (PBNCs) are applied to a disposable platinum screen-printed electrode (Pt-SPE). Subsequently, a biomimetic sensing layer is generated by electropolymerization of ortho-phenylenediamine (o-PD) in the presence of Myo, which forms molecularly imprinted polymer (MIP) sites by cyclic voltammetry (CV). The electropolymerization process takes place in a potential range of −0.2 V to +0.8 V, for five cycles at a scan rate of 50 mV/s, in a 10 mmol/L o-PD solution. After polymerization, the electrode is incubated in trypsin for 2 h to create Myo-specifically imprinted cavities. The structural and morphological properties of the biomimetic layer were analyzed by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The direct detection of Myo was analyzed by differential pulse voltammetry (DPV). The results showed a linear response to Myo concentrations ranging from 1.0 ag/mL to 10 ng/mL, a limit of detection (LOD) of 0.76 ag/mL, and a R² value of 0.9775. The absence of an external liquid redox probe simplifies the sensor design, improves portability, and reduces the complexity of the assay, making it more suitable for PoC. Full article

Coccidiosis in chickens is a parasitic disease caused by Eimeria species, resulting in significant economic losses to the poultry industry. Among these species, Eimeria tenella is considered the most virulent pathogen, with its infection strongly associated with the apoptotic response of host cells. Eimeria tenella modulates host cell apoptosis in a stage-specific manner, suppressing apoptosis in the early phase to promote its intracellular development and triggering apoptosis in later stages to facilitate parasite egress and disease progression. This study established an in vitro infection model using 60 fifteen-day-old chick embryo cecal epithelial cells and infecting the cells with Eimeria tenella sporozoites at a 1:1 ratio of host cells to sporozoites. The aim was to examine the relationship between parasitic infection and the apoptotic response of host cells in the chick embryo cecal epithelial cells infected with E. tenella. The roles of the mitochondrial permeability transition pore (MPTP) and cytochrome c in intrinsic apoptosis were examined through the application of cyclosporine A (CsA), N, N, N’, N’-tetramethyl-1,4-phenylenediamine (TMPD), and ascorbate (Asc). TUNEL staining, ELISA, and flow cytometry were performed to evaluate apoptotic rates. CsA, TMPD, and Asc significantly (p < 0.01) decreased cytochrome c release, caspase-9 activation, and apoptotic rates from 24 to 120 h post-E. tenella infection. These findings highlight the significance of cytochrome c-mediated, mitochondria-dependent apoptotic pathways in parasitized chick embryo cecal epithelial cells. Full article