Chemical Papers最新文献

This study aims to enhance the energy storage capabilities of flexible supercapacitors by fabricating graphene-doped MnO₂-coated carbon cloth electrodes through a hydrothermal method. This technique was selected for its ability to uniformly disperse MnO₂ nanorods (~ 50 nm thick) on carbon surfaces, while anchoring graphene plates at rod interfaces to improve conductivity. Comprehensive characterization including XRD, FTIR, SEM, and TEM confirmed the structural integrity of the electrodes. Electrochemical analysis (CV, GCD, and EIS) revealed a diffusion-controlled charge storage mechanism, achieving a specific capacitance of 513 F/g (205 F/cm³–1027 mF/cm²) at a current density of 1 A/g. The electrodes demonstrated impressive energy-power densities of 45.6 Wh/kg–200 W/kg and retained 87% of their initial capacity after 2500 cycles, indicating robust cyclic stability. Remarkably, the inclusion of graphene enhanced the performance nearly threefold compared to similar electrodes in the literature, making these materials highly promising candidates for next-generation supercapacitors.

Leishmaniasis, a protozoan disease with significant global morbidity, manifests as Cutaneous, Mucocutaneous, and Visceral forms caused by Leishmania species. Visceral Leishmaniasis (VL), caused by Leishmania donovani, poses particular fatality due to its infiltration of the central nervous system (CNS). The emergence of multidrug resistance (MDR) in L. donovani underscores the need for alternative therapeutic strategies. Plant secondary metabolites, acting as inhibitors against L. donovani's survival pathways, present a promising avenue for drug development. The cysteine synthase pathway, crucial for L. donovani’s survival, can be targeted for inhibition, focusing on the O-acetyltransferase (OASS) enzyme. OASS, pivotal in this pathway and absent in humans, becomes an attractive drug target. Initiating with the selection and optimization of OASS's 3D structure (PDB Id-3TBH), virtual screening against a plant metabolite library identified lead compounds with high binding affinities. Four potential candidates were shortlisted based on estimated free energy of binding and drug likeliness. These candidates underwent molecular dynamics simulations, providing insights into protein–ligand interactions via structural analyses. Additionally, Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) analysis calculated binding free energies. Results indicated Skimmin (IMPHY007363) as a potential lead molecule for inhibiting OASS in Leishmania donovani, showing promise for further drug development against this devastating disease.

Graphical Abstract

Alzheimer's disease (AD) is characterized by cognitive decline and behavioral changes, with the formation of amyloid-beta (Aβ) plaques as one of the underlying mechanisms responsible for its progression. Advanced glycation end-products (AGEs) have also been linked to AD pathology, contributing to oxidative stress and amyloid plaque formation. Pandanus amaryllifolius has shown potential in inhibiting Aβ aggregation and AGE formation, suggesting a multifaceted approach for managing AD. In this study, alkaloids isolated from the crude base extract of P. amaryllifolius leaves were explored for their in vitro inhibitory effects on AGEs formation and Aβ aggregation. Results showed that pandamarilactonines A (3) (74% at 100 μg/mL and 50% at 50 μg/mL) and B (8) (56% at 100 μg/mL and 34% at 50 μg/mL) exhibited highest inhibitory activities on AGEs formation using the BSA-dextrose model. Pandamarilactonine A (3) (74%) also exhibited Aβ aggregation inhibition, along with pandanusine B (4) (66%) and pandamarilactonine B (8) (63%), using the Thioflavin T assay. Molecular docking studies further supported these findings, revealing strong binding affinities between the alkaloids and Aβ oligomeric structures. Pandamarilactonine A (3) and pandamarilactonine B (8) showed the best binding affinity to the Aβ dodecameric structure (BE = − 7.5 to − 7.7 kcal/mol), thus corroborating with the in vitro results. Hence, these findings suggest that the Pandanus alkaloids could serve as promising candidates for further development as therapeutic agents against AD. However, in vivo studies are necessary to validate these findings, and further exploration of the structure–activity relationships could aid in the rational design of drug candidates utilizing the Pandanus alkaloids.

Emulsions in petroleum production pose challenges like equipment corrosion, pipeline pressure drops, pumping costs, and catalyst poisoning, leading to increased production costs and technical and environmental issues. The complexity of emulsions necessitates using cost-effective and efficient de-emulsifiers for effective treatment. Desalting units are often installed in crude oil production units to remove water-soluble salts from an oil stream. To optimize this process, the desalting unit should be modeled. The research employs Response Surface Methodology (RSM) to analyze the efficiency of the desalting unit based on various input parameters. The result shows that the mentioned model agrees with the experimental data. The experiments were designed using response surface methodology; these parameters and their interaction are significant, and determination coefficient R² for water content and salt concentration equal 0.9246 and 0.9901 in respective in addition difference between R_adj and R_pred less than 0.2 for two responses, R_adj and R_pred for water content 0.8491 and0.6082 and salt concentration 0.9803 and 0.9464, respectively. The result revealed that minimum water content of 0.03%(V/V) and salt concentration of 85 ppm, which agreement with predicted responses, was 0.05%v/v and 70 ppm, respectively, when the temperature was 45.1 °C, API 29, initial water content was 2.07 and initial salt concentration was 5344.04, respectively.

One of the most important processes to obtain gasoline with high octane numbers is isomerization. In this paper, Pt/TiO₂ was prepared successfully by using the sol–gel method by hydrolysis of titanium tetraisopropoxide as a titania source with ethanol and then platinum was loaded on the synthesized catalyst; the result shows that the sample prepared has a good crystallinity with a surface area of about 85 m²/g and a pore volume of 0.1938 cm³/g, while XRD shows that the prepared sample was anatase phase. The effect of both temperature and liquid hourly space velocity of the prepared catalyst was achieved by hydroisomerization of n-hexane in a fixed bed reactor with a temperature of 200–275 °C and LHSV 0.5–2h⁻¹. The results show that the conversion of n-hexane was increased with increasing temperature and decreasing LHSV; the maximum conversion achieved at temperature 275 °C and 0.5 h⁻¹ was 63.54% at atmospheric pressure.

Traditional antifouling coatings for metal substrates typically involve three layers including an anticorrosion primer, a midcoat, and an antifouling paint. However, the limited bonding capacity between these layers restricts their effectiveness in industrial metal corrosion protection. In this work, we developed a single coating by dipping method on steel substrate that combines the anticorrosion properties of zinc and the antifouling properties of copper, using an ethyl silicate binder. This pigment mixture, containing flake ZnAl (5 wt%) and Cu₂O (10 wt%) with varying spherical Zn content (30, 40, and 50 wt%), was created and tested for its anticorrosion capabilities. Electrical properties were characterized using electrochemical impedance spectroscopy and the polarization curve method. Results showed that after 60 days of immersion in 3.5 wt% NaCl solution, the low-frequency impedance modulus of the coatings increased with higher Zn content, with the 40 wt% Zn content achieving the highest efficiency, showing an impedance modulus value of 56.43 kΩ cm². Stability evaluations revealed an increased release of Zn and Cu content in samples with higher Zn content. Antifouling assessments in natural seawater demonstrated that the Zn40 integrated coating had the lowest fouling density among the tested samples, with hard fouling surface coverage (FR ≥ 40) at 9.31% after three months. These findings highlight the effectiveness of the integrated coating utilizing Zn and Cu in providing robust corrosion protection, preventing settlement, and inhibiting fouling marine growth.

Salmonella is a common type of Gram-negative bacteria that is found in many food sources and can not only survive but also easily grow under unfavorable environmental conditions. Therefore, controlling Salmonella bacteria in agriculture, food, and processing industries is always a challenging issue, and the identification and detection of very small amounts of it are of great importance. Surface-enhanced Raman spectroscopy (SERS) has emerged as a reliable and accurate method for rapidly detecting small quantities of biological and chemical substances. In this study, a SERS biosensor was developed by utilizing a filter paper (FP) substrate that was coated with silver nanoparticles (AgNPs). The AgNPs were synthesized through a chemical reduction process and underwent characterization using DLS, UV–Vis, TEM, and FE-SEM. By coating the FP substrate with AgNPs, active plasmonic sites were created, enabling the detection of Salmonella molecular vibrations (MVs). When the FP substrate was exposed to Salmonella, an interaction occurred between the bacteria and the AgNPs, facilitating the identification of extremely low amounts of Salmonella. Additionally, the antibacterial properties of the AgNPs were observed. The SERS FP substrate exhibited the capability to detect Salmonella at concentrations as low as 10¹ CFU. Experimental measurements were conducted to obtain the Raman spectra and peak signals, and the reproducibility of the substrates was confirmed. The empirically calculated enhancement factor for identifying the Salmonella MVs was determined to be 1.448 × 10⁵; while, a numerical estimation yielded a value of 3.740 × 10⁵.

Dithiocarbamate (DTC) derivatives including S-alkylated compounds, metal-complexes, or the combination of some of these derivatives with known chemotherapeutic drugs have been extensively studied for their anti-tumor activities. Interestingly, the anti-proliferative activities of DTC salts have not been studied. A new series of DTC salts including alkyl-, morpholinyl-, and benzyl-containing derivatives was synthesized. The compounds were assessed for their cytotoxic activity against four human cancer cell lines (MCF7, ES2, HSC3, and RKO). Most of the synthesized compounds demonstrated excellent to moderate activity against MCF7, ES2, and HSC3 cancer cells. However, all the compounds showed low activity against RKO cell line (IC₅₀ > 10 μM). Notably, compound 1 with methyl groups showed the most potent anti-proliferative activity against the three cell lines, followed by compounds 2 and 6 with ethyl and morpholinyl groups, respectively. Importantly, the anti-proliferative activity significantly decreased as the size of the N-substituents increased. Compounds 4, 5, and 7 containing butyl, isobutyl, and benzyl groups, respectively, exhibited low activity against all cell lines (IC₅₀ > 10 μM). The three leading compounds (1, 2, and 6) induced apoptosis in HSC3 head and neck cancer cells as evident by cell shrinkage, nuclear fragmentation, and upregulation of caspase 3, 8, and 9 expression.

The process of adapting to changing environmental conditions plays a pivotal role in driving plant diversification. Elevational gradients provide a unique chance to explore adaptation to various climatic conditions. Aquilegia fragrans Benth. recognized as an important medicinal plant is distributed across various habitats with varying altitudes in the Kashmir Himalayan region. Nevertheless, a comprehensive examination of morphology and antioxidant phytochemicals concerning various environmental factors such as altitude and habitat conditions is currently lacking. The goal of this study is to understand the morphological and phytochemical variations, as well as antioxidant activity, in A. fragrans across diverse altitudes and habitats within the study area. The current investigation unveiled significant (p < 0.05) distinctions among populations of A. fragrans based on morphological, phytochemical, and antioxidant activity parameters. Across ten sampling sites phenolics (174 ± 2 mg GAE/g), flavonoids (109.14 ± 0.29 mg QE/g), BGFW (below ground fresh weight; 168.35 ± 4.3 g) and BGDW (below ground dry weight; 55.02 ± 1.42 g) were recorded maximum in Razdhan Pass followed by Mohand Marg population. Furthermore, the present investigation consistently validates the impact of altitude as a significant variable on the accumulation of phenolics and flavonoids in A. fragrans, and its antioxidant activity. Therefore, this research will be useful in identifying elite populations of target species and can aid in our knowledge of how plants modify the synthesis of secondary metabolites to adapt to harsh climatic conditions at higher altitudes. Moreover, HR-LCMS-QTOF was employed to identify bioactive compounds in the methanolic rhizome extract.

This study presents the production of polypropylene (PP) biocomposites utilizing different biomasses such as apricot kernel shell (AKS, 48% lignin), hazelnut shell (HS, 40%), walnut shell (WS, 35% lignin), and corn cob (CC, 15% lignin, 40% cellulose). The biocomposites were manufactured using a twin-screw extruder by varying the type and amount (5% to 20%) of biomass used as filler. The characterizations are done using spectral, thermal, and mechanical methods. In addition, using two different brands of PP samples the effects of crystallinity on thermal and mechanical properties of the biocomposites were examined. The composition of the biomass was important; higher lignin content (as in AKS) resulted in better compounding due to its hydrophobic behavior. Another important factor affecting the performance of the biocomposites was filler content. The optimum performance was obtained 10% content. In general, addition of the filler caused an increase in crystallinity which was detected by spectral and thermal methods.