Chemical Papers最新文献

Near-infrared (NIR) fluorescence emitting probes are of potential interest in the field of bioimaging due to good penetration and minimal photodamage to tissues. Despite the remarkable fluorescence properties of carbon dots (CDs), their low emission quantum yield and need for surface modification limit their applicability. CDs are intercalated into multilayer structures to minimize internal quenching and modify surface functional groups, which improve sensitivity and selectivity. Layered zinc hydroxide (LZH) stands out among other layered materials because of its stability, biocompatibility, luminescence, and capacity to be used as a drug delivery system. By incorporating LZH with fluorophore can transform it as prominent bioimaging probe. In this study, we used a direct and low-cost microwave-assisted technique to successfully intercalate nitrogen-doped carbon dots (NCDs) in layers of zinc hydroxide (NCLZH). Formation of layers of NCLZH is supported by the HRSEM image. When excited at 700 nm, NCLZH exhibit high NIR emission at 768 nm, suggesting that it could be a viable substitute for contact-free bioimaging in healthcare. Furthermore, addition of NCDs to LZH enhanced the anticancer activity of NCLZH with IC₅₀ 75 µg/mL, and cytotoxicity studies of NCLZH show 92% cell viability towards adult dermal fibroblast cell lines which confirms NCLZH as Photodamage-Free Bioimaging Tool. Hence, NCLZH can function in future as an efficient fluorescent probe in real-time fluorescence-guided surgery for cancer diagnosis and treatment which is a potential extension of the current work in future.

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Chalcones are a highly effective chelating agent used in spectrophotometric vanadium ion detection. It was observed that potassium (E)-(4-(3-(4-hydroxy-3- methoxyphenyl) acryloyl)phenyl) carbamodithioat (HMAPC) reagent formed a yellow colored complex with vanadium ion at 420 nm. Vanadium ion was chelated with the chalcone (HMAPC) reagent in acidic medium at pH = 6 using Britton–Robinson buffer (BRB). The effect of reagent volume, pH, temperature, time, and interferences was studied. The stoichiometric composition of the formed complex was found to be 1:2 (metal: reagent) by Job's method of continuous variation and mole ratio methods. Beer's law was obeyed in the range of 1–32 µg mL⁻¹ with molar absorptivity of 1589.32 L mol⁻¹cm⁻¹, sensitivity of 0.03225 µg mL⁻¹, regression coefficient of 0.9945 and an estimated detection limit of 0.1354 µg mL⁻¹. The accuracy (recovery percentage) was ranged between 97.2 and 104.8%, and precision (R.S.D.%) is less than 1.5%. A colorimetric method equipped with a portable microfluidic device (µ-chip), as well as a smartphone (iPhone), is used to measure vanadium concentrations. The resulting color changes were taken by a smartphone camera. The obtained images were analyzed by ImageJ software to assay the vanadium concentration. Under the identical experimental settings, the suggested approach and the spectrophotometric method were compared, and it was discovered that both were advantageous. The suggested approach technique was straightforward and easy to use, and the findings indicated that it was practical and might be used for on-site analysis. It also had promising properties of mobility and low manufacturing cost, making it appropriate for the detection of vanadium in crude oil.

The word nanotechnology became a humming word of decennary. Nanotechnology application hikes oil and gas industry growth, as witnessed by undertaken research in the past few years. The application of nanotechnology has penetrated through different disciplines in the petroleum industry. This study covers nanotechnology applications in exploration, drilling, enhanced oil recovery, and well cementing. In order to improve the recovery of a field, nanoparticles can change certain formations and oil properties, which is beneficial. Accurate control and modification of particles at measurements (1–100 nm) have become the development direction of the oil and gas industry. The major challenges linked with the usage of nanoparticles are transportability in reservoir rocks and stability in liquid media; in order to achieve new applications and better performance, synergistic effects studies are proposed for examination in future nanotechnology research. The technology resulting from the synergistic studies can strengthen future nanotechnology applications in the oil and gas industry, chiefly for extreme pressure and temperature conditions. Most of the nanotechnology research in the oil and gas industry investigates laboratory experimental work. The lowest possible nanoparticle concentration is suggested for cost-effectiveness while achieving the desired performance. Further advancement in nanotechnology boosts the application of nanotechnology in the petroleum industry.

In this work, the surfaces of cellulose nitrate (CN) membranes were modified through interfacial polymerization, employing halloysite nanotubes (HNTs) as additives to form a thin-film composite (TFC). The formation of CN-polyamide-HNT composite membranes (CN/HNTs) was confirmed by analyzing their structural and surface properties using various methods, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). The morphology and performance of the fabricated CN/HNT membranes exhibited a clear improvement, including alterations in surface roughness, charge, and hydrophilicity. The water contact angle and porosity of the membranes were also measured in relation to the HNT content (0–0.1 wt.%). As the HNT content increased, the contact angle, mean roughness, and zeta potential decreased from 56° to 26°, 65.2 to 26.5 nm, and − 13.5 to − 25.9, respectively. Although the pure water flux decreased from 61 to 39 L/m² h with the addition of HNTs, salt rejection increased with higher HNT content. Salt rejection values of approximately 96, 97, 92, and 95% were achieved for NaCl, Na₂SO₄, MgCl₂, and MgSO₄, respectively, reflecting improvements of 71, 59, 51, and 51%, with 0.1 wt.% being the optimal concentration for HNTs. The membranes were evaluated using samples of real seawater and groundwater. They demonstrated effective salt rejection and significantly reduced the total dissolved solids (TDS) in seawater. For the groundwater sample, the total hardness decreased markedly from 680 to 87 mg/L, corresponding to an 87% reduction.

The current generation of wound dressings has several disadvantages, including a lack of antibacterial efficacy, inadequate oxygen and water vapor permeability, and suboptimal mechanical properties. This study explores the synthesis and evaluation of carboxymethyl cellulose-based hydrogels, specifically CMCF and CMCF-PO, which incorporate Platanus orientalis L. extract. Characterization through scanning electron microscopy showed that both hydrogels possessed porous surfaces with distinct textures. Fourier Transform Infrared Spectroscopy analyses confirmed successful crosslinking via ester bond formation, indicated by a shift and narrowing of the O–H stretching peak. The swelling experiments highlighted that CMCF-PO exhibited significantly higher water absorption than CMCF. Antibacterial assessments demonstrated that CMCF-PO displayed superior antibacterial activity against various bacterial strains, particularly Pseudomonas aeruginosa, with the lowest minimum inhibitory concentration values recorded, indicating its effectiveness in bacterial inhibition. In addition, both hydrogels significantly reduced biofilm formation, underscoring their potential in combating biofilm-related infections. In vitro biocompatibility tests revealed high cell viability, with CMCF-PO achieving around 91% viability after 48 h, confirming its low cytotoxicity. These findings suggest that CMCF-PO enhances mechanical and antibacterial properties and exhibits excellent biocompatibility.

A photochromic dye (TPDA) with helical structure was configured by attaching triangle terthiophene to triphenylamine units. It exhibits typical photochromic behavior when irradiated with UV (390 nm)/visible light (> 410 nm). Moreover, TPDA in tetrahydrofuran (THF) can be switched alternately between color and colorless state. In addition, it exhibits highly emissive character in THF and could emit bright blue fluorescence by UV irradiation. And the fluorescence emission efficiency was estimated to be 0.41. Under the UV light irradiation, a ring-closure reaction occurred and the blue fluorescence was quenched effectively at the same time. At photo-stationary state, the quantum yield was lowered to 0.10. Therefore, a switch controllable fluorescence “on–off” molecular system was developed when light irradiation cycle established (UV/visible light). Optimization of the dye structure was performed using density functional theory at the DND/B3LYP level of theory. The structural analysis reveals that the shorter distance between reactive atoms (< 4.2 Å) in the triangle terthiophene unit promotes the smoothly photochromism of TPDA.

In this study, an oral pH-responsive carrier, carboxymethyl cellulose/hydroxyapatite/Fe₃O₄ bio-nanocomposite hydrogel beads (CMC/HAp/Fe₃O₄), was prepared to control the release profile of anticancer doxorubicin (DOX) drug. Surface morphology of the CMC/HAp/Fe₃O₄ bio-nanocomposite hydrogel beads was studied using different techniques. The magnetic measurement studies revealed a good superparamagnetic behavior for the prepared bio-nanocomposite hydrogel beads with a saturation magnetization of 28.73 emu/g. The pH-responsive drug release was verified by in vitro release test and showed a lower release at acidic media (pH 1.2) and a higher release under alkaline conditions (i.e., pH 7.4 and 6.8). Besides, the MTT assay revealed that the DOX-loaded CMC/HAp/Fe₃O₄ has the desired cytotoxicity against SW480 cells. According to the results, the prepared bio-nanocomposite hydrogel beads have a high potential for being used as biomaterials.

The current study describes the development of a simple, direct, low-cost, and high-throughput method to determine chemical oxygen demand (COD) in wastewater samples using UV–Vis spectroscopy combined with machine learning techniques. Robust models were developed using 289 wastewater samples collected in seven distinct sewage treatment plants (STPs) in Paraná state, Brazil. Principal components analysis (PCA) showed a considerable tendency to group samples from STPs that employed similar wastewater treatments. Multivariate calibration models were built using partial least squares (PLS) regression combined with inspection of regression vector and ordered predictors selection (OPS) to select relevant spectral variables. Results indicate the models are suitable to predict COD, with root mean square error of calibration (RMSEC) and prediction (RMSEP) lower than 14.19 and 15.00 mg L⁻¹ O₂, respectively. Additionally, the models showed ratio performance deviation (RPD) higher than 2.75, indicating an excellent prediction accuracy. The analytical GREEnness (AGREE) score for the proposed method is 0.82, confirming its greenness characteristic. These results demonstrate that the proposed method can be applied in COD determination, allowing fast sample screening at a low cost with no solvent consumption and generation of waste.

This study investigates the rheological behavior of marble powder, raw flour, and talc powder in a fluidized bed system equipped with a two-blade mechanical stirrer. Shear tests were conducted below the fluidization threshold (0 < U < U_mf) and at varying bed heights (0 < z < H_mf) to evaluate the influence of key factors on powder rheology. A rheological model, based on Janssen’s analysis, was developed to estimate the torque and normal stress within the particle bed, accounting for powder properties and aeration rate across small-scale bed heights (0 < z < H_mf). The Kozeny–Carman theory for cylindrical and linear pore structures was applied to describe pressure gradient variations. The model produced accurate predictions that aligned well with experimental data across all three powders, within the conditions of “0.1 < ΔP_z/ΔP_mf < 0.6” and “1 cm < z < H_mf.” Results showed that increasing bed height elevates both stress and the required torque, while aeration reduces these values without affecting stress distribution or the overall rheological properties. Notably, each powder exhibited distinct rheological behavior: Talc required the highest torque for stirring, whereas marble powder demonstrated superior flowability and rheological performance under agitation. Key factors influencing powder rheology include particle diameter, bulk density, cohesion, and internal friction angle. Additionally, very smooth and fine particles tend to agglomerate, complicating their flow and separation.

The growing availability of vacuum residues has provoked the development of studies that may improve refining processes to increase capacity conversion. Therefore, conducting a detailed analysis on the trend of the physicochemical properties of representative fractions is necessary. In this work, a set of vacuum residues were fractionated using n-hexane as a supercritical fluid and the molecular distillation process. The results show that the increase in density, micro-carbon content and molecular weight in the extractable fractions is associated with their SARA compositional. As a result, density determination for these extractable fractions by standard methodologies, such as ASTM D70, has shown limitations for samples with densities higher than 1.0879 g/ml. To measure the density of vacuum residues and their fractions, a density dilution methodology was conducted, using toluene as a solvent. In this study, 87 fractions obtained from different vacuum residues and processed with n-hexane and molecular distillation were selected. The proposed dilution methodology allows measuring densities with repeatability and reproducibility values of 0.0031 and 0.0061 g/g/ml, respectively. The average boiling point (Tb50) of vacuum residues and their fractions was correlated with density and molecular weight, to estimate their quality. The correlations of density and average boiling point properties Tb50 exhibited R2 correlation coefficients of 0.9949 and 0.9908 with P values less than 0.0031. The values of these statistical parameters show that the developed correlations have a confidence level of 95%.