Search Results (490)

A two-dimensional porous silica nanomesh (VMT-SiO₂) was used as a carrier to prepare MgO-CuO-based catalysts and tested for one-step ethanol conversion to 1,3-butadiene. The effects of catalyst composition and different calcination temperatures on the reaction performances of the catalysts were mainly investigated. Combining various characterization techniques, such as HRTEM, XRD, FT-IR, and TPD, it was found that the dispersion state of MgO and CuO on the catalyst surface was related to the calcination temperature, which further induced changes in the acid–base properties. A small number of acidic centers and a proper proportion of medium–strong alkaline centers maintained a subtle balance, affecting catalytic performance. A lower total acid/base ratio is more conducive to ethanol conversion and 1,3-butadiene formation. At the same time, the synergistic effect of CuO and MgO promotes the transformation of the intermediate acetaldehyde product, which is the key to ensuring the subsequent aldol condensation and then 1,3-butadiene formation. Among the investigated samples, the CuO/MgO-VMT-SiO₂ catalyst calcined at 500 °C exhibited the best catalytic performance, with an impressive ethanol conversion of 47.8% and 1,3-butadiene formation (42.6% selectivity and a space-time yield of 182.0 g_C4H6·kg_cat⁻¹·h⁻¹). Full article

The conjugate of rhein and artesunate have shown promising effects in inducing immunogenic cell death (ICD) and inhibiting tumor growth. Rhein, a natural anthraquinone derivative found in various medicinal plants such as Rheum palmatum, possesses diverse pharmacological properties including anti-inflammatory and anticancer activities. Artesunate, a sesquiterpene lactone extracted from Artemisia annua, exhibits potent antimalarial efficacy and has garnered attention for its potential anticancer properties. Through rational drug design, the conjugation of rhein with artesunate has yielded compounds capable of selectively targeting mitochondria of cancer cells, inducing oxidative stress-mediated ICD, and enhancing the immunogenicity of tumor cells. The conjugate leverages the inherent cytotoxicity of artesunate while incorporating the capability to selectively target the mitochondria of rhein, thereby fostering a special approach to immunotherapy for cancer. Upon accumulation in the mitochondria, these compounds induce the generation of reactive oxygen species (ROS), leading to mitochondrial membrane potential (ΔΨm) reduction and endoplasmic reticulum (ER) stress. Notably, the conjugate exhibits far more potent ICD-inducing properties than their parent compounds. In vivo studies have demonstrated that the vaccine, when treated with the conjugate, effectively suppresses tumor growth. Full article

The global emergency of antimicrobial resistance has drawn several efforts to evaluate new drug candidates, such as natural defensive biomolecules. Ocellatins are a group of antimicrobial peptides found in anurans of the Leptodactylidae family. This work investigated the presence of antimicrobial peptides in the skin secretion of Leptodactylus vastus from the Brazilian northeast. The secretion was fractionated by RP-HPLC, and the fractions were screened for antibacterial activity. A peptide isolated from the most active fraction was characterized for primary structure and evaluated for antibacterial activity, cytotoxicity to murine melanoma cells (B16-F10), and hemolytic activity. The RP-HPLC profile displayed 26 fractions, with fraction 25 being the most active. One of the two peptides present in this fraction had the primary structure determined, belonging to the group of ocellatins. Since it was not identical to other ocellatins previously reported, it was named ocellatin-VT. This peptide especially inhibited Gram-negative bacteria growth, with the highest activity against Acinetobacter baumannii and Escherichia coli (growth inhibition was higher than 95% at 8 and 16 µM, respectively). Ocellatin-VT was weakly cytotoxic to B16-F10 cells and showed low hemolytic activity. In conclusion, a new ocellatin was isolated from L. vastus skin secretion that was active against non-resistant and multidrug-resistant bacteria. Full article

Co doped bismuth magnesium tantalate with a pyrochlore structure (sp. gr. Fd-3m) was synthesized for the first time using the standard ceramic method. Single phase Bi₂Mg_1−xCo_xTa₂O₉ samples were found to be formed when x < 0.7 in the X-ray phase analysis. However, with a higher cobalt content in the samples, the impurity phase β-BiTaO₄ (sp. gr. P-1) is detected, and its amount is proportional to the degree of cobalt doping. The formation of solid solutions is evidenced by a uniform increase in the unit cell parameter of the Co,Mg co doped bismuth tantalate phase with an increase in the content of cobalt ions in the samples from 10.5412(8) (x = 0.3) to 10.5499(8) Å (x = 0.7). The samples exhibit a porous microstructure consisting of chaotically oriented and partially fused elongated grains measuring 1–2 μm. The dependence of the ceramic grain size on the n(Mg)/n(Co) ratio was not determined. X-ray spectroscopy (ear dge X-ray bsorption ine tructure (NEXAFS) and X-ray photoelectron spectroscopy (XPS)) was used to study the charge state of ions in Bi₂Mg_1−xCo_xTa₂O₉. The NEXAFS and XPS data showed that doping with cobalt and magnesium did not change the bismuth and tantalum oxidation states in pyrochlore; in particular, the ions maintained their oxidation states of Bi(+3), Mg(+2) and Ta(+5). The energy position of the peaks of the Ta4f-, Ta5p-, Ta4d spectra had a characteristic shift towards lower energies compared to the binding energy in pentavalent tantalum oxide Ta₂O₅. A shift towards lower energies is characteristic of a decrease in the effective positive charge; in particular, for the Ta4f and Ta4d spectra we presented, this energy shift was ΔE = 0.65 eV, and in the region of the Ta4d edge—0.55 eV. This in turn allowed for us to assume that tantalum atoms have the same effective charge +(5-δ). The oxidation state of cobalt ions was predominantly 2+ and partially 3+, according to NEXAFS spectroscopy data. Full article

Oxygen evolution reactions (OER) are often the decisive step in determining the water electrolysis rate. The first row of transition metals and their derivatives, represented by Ni and Fe, have attracted much attention due to their excellent OER performance. Here, we develop a one-step strategy for preparing oxygen-evolving electrodes, in which the NiFeOOH-modified NiFe layered double hydroxide (NiFe-LDH) nanosheet is supported by nickel foam. At 100 mA·cm⁻², the overpotential of NiFeOOH-NiFe-LDH was just 227 mV, and the duration times were over 200 h in 1 mol·L⁻¹ KOH. Furthermore, the co-existence of LDH and hydroxyl oxides helps the oxygen evolution reaction. These results suggest the potential for this synthesis strategy to provide a low-cost, highly active OER electrocatalyst for industrial water splitting. Full article

Gas-filled microbubbles are well-established contrast agents for ultrasound imaging and widely studied as delivery systems for theranostics. Herein, we have demonstrated the promising potential of the hydrophobin HFBII—a fungal amphiphilic protein—in stabilizing microbubbles with various fluorinated core gases. A thorough screening of several experimental parameters was performed to find the optimized conditions regarding the preparation technique, type of core gas, HFBII initial concentration, and protein dissolution procedure. The best results were obtained by combining perfluorobutane (C₄F₁₀) gas with 1 mg/mL of aqueous HFBII, which afforded a total bubble concentration higher than 10⁹ bubbles/mL, with long-term stability in solution (at least 3 h). Acoustic characterization of such microbubbles in the typical ultrasound frequency range used for diagnostic imaging showed the lower pressure resistance of HFBII microbubbles, if compared to conventional ones stabilized by phospholipid shells, but, at the same time, revealed strong non-linear behavior, with a significant harmonic response already at low acoustic pressures. These findings suggest the possibility of further improving the performance of HFBII-coated perfluorinated gas microbubbles, for instance by mixing the protein with other stabilizing agents, e.g., phospholipids, in order to tune the viscoelastic properties of the outer shell. Full article

Metal–organic frameworks (MOFs) have been observed to exclusively eliminate dyes confined within their respective pores. In this investigation, the synthesis of a breathable MOF structure, MIL-88B(Fe), was pursued with the objective of circumventing restrictions on pore size to enhance its adsorption capabilities. The synthesis of MIL-88B(Fe) was carried out via the assisted solvothermal method at 373 K using inexpensive yet environmentally benign FeCl₃·6H₂O, 1,4-benzenedicarboxylic acid, and DMF as a metal precursor, linker, and solvent, respectively. Furthermore, the MOF was subjected to extensive analytical characterisation using XRD, FT-IR spectroscopy, N₂ gas sorption, TGA, and SEM. The experimental data showed that the utilisation of MIL-88B(Fe) with a dose level of 5 mg for 180 min at a pH of 9 led to the highest levels of adsorption for both dyes, with 162.82 mg g⁻¹ for methylene blue (MB) and 144.65 mg g⁻¹ for rhodamine B (RhB), as a result of the contrast in the molecular size between each dye. The Langmuir and Freundlich models demonstrated a correlation with isotherms, while the thermodynamic analysis demonstrated that MIL-88B(Fe) exhibits distinct endothermic and breathable properties. The efficacy of MIL-88B(Fe) adsorbent for MB and RhB in aqueous solutions indicated exceptional performance, stability, and noteworthy reusability performance. Full article

Ibrutinib (IBR) is a tyrosine kinase inhibitor investigated for treating solid and non-solid tumors. Considering the advantages that a topical application of IBR could generate in terms of dose reduction and side effects in skin cancer treatment, this paper presents a simple and selective HPLC method for determining IBR concentration in in vitro skin permeation studies to support the development of topical formulations. The method uses a reversed-phase C₁₈ column and a mobile phase composed of acetonitrile and 0.01 mol/L phosphoric acid at pH 3.5 (35:65 v/v), flowing at 1.0 mL/min. The oven temperature was set at 35 °C, the injection volume was 20 μL, and UV drug detection was performed at 259 nm. The validation procedure certified that this method was selective for IBR determination even when extracted from human or porcine skin matrices. The method was linear over a range of 0.2 to 15.0 μg/mL, precise, robust, and accurate, with recovery rates from the skin layers higher than 89.5 ± 5.9% for the porcine skin and higher than 92.0 ± 0.2% for the human skin. The limits of detection and quantification were 0.01 and 0.02 μg/mL, respectively. The method showed, therefore, to be adequate for use in further skin permeation studies employing IBR topical formulations. Full article

This work was the first investigation of the essential oil composition of Goniothalamus tortilipetalus M.R.Hend. The aim of this study is to investigate the essential oil composition extracted from different parts of Goniothalamus tortilipetalus M.R.Hend., including flowers, leaves, and twigs, and to evaluate their antioxidant and antibacterial activities. The Clevenger apparatus was used for hydrodistillation to prepare the essential oils. The essential oils were investigated using gas chromatography–mass spectrometry (GC-MS). The three major compounds of the flowers were bicyclogermacrene (15.81%), selin-11-en-4-α-ol (14.68%), and E-caryophyllene (7.02%), whereas the leaves were p-cymene (39.57%), ascaridole (9.39%), and α-copaene (9.12%). In the case of the twigs, α-copaene (10.34%), selin-11-en-4-α-ol (8.85%), and p-cymene (7.76%) were the major compounds. The flower essential oil showed antioxidant activities with IC₅₀ values of 725.21 µg/mL and 123.06 µg/mL for DPPH and ABTS assays, respectively. The flower essential oil also displayed antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus, Salmonella typhimurium, and Shigella flexneri, with the same MIC value of 640 µg/mL. Full article

In this study, Melia azedarach fruit extract was used as a reducing agent and copper chloride dihydrate (CuCl₂·2H₂O) was used as a precursor in the synthesis of copper oxide nanoparticles (CuO NPs). The UV–visible spectrum showed a characteristic absorption peak of CuO NPs at 350 nm. The surface properties of the adsorbent were analyzed through various techniques, indicating the successful formation of CuO NPs. The impacts of several factors, including initial pH (4 to 8), a dose of CuO NPs adsorbent (0.01–0.05 g), dye initial concentration (10–50 mg·L⁻¹), and contact times ranging from 5 to 120 min, were examined in batch adsorption studies. Based on the experimental results, the Langmuir isotherm is well-fitted, indicating MB dye monolayer capping on the CuO NPs surface with 26.738 mg·g⁻¹ as a maximum adsorption capacity Q_m value. For the pseudo-second-order kinetic model, the experimental and calculated adsorption capacity values (q_e) exhibited good agreement. Full article

The design and development of useful chemosensors for the ultra-trace detection of environmental pollutants and contaminants is a topical area of research. Herein, we report a new nanoscale emissive Zn(II) coordination polymer (TB-Zn-CP) for differential fluorescence sensing of various antibiotics in water. TB-Zn-CP was synthesized using a unique V-shaped green emitting 4-amino-1,8-naphthalimide Tröger’s base (TBNap) fluorophore. The structural and morphological features of TB-Zn-CP were characterized by various standard spectroscopic and microscopy techniques. The fluorescence titration studies in water demonstrated a remarkable sensitivity and differential fluorescence sensing properties of TB-Zn-CP for the fast detection of different antibiotics. Among different antibiotics, chloramphenicol (CRP), 1,2-dimethyl-5-nitroimidazole (DMZ), and sulfamethazine (SMZ) displayed the highest fluorescence-quenching efficiency and superior sensitivity in their detection. The differential sensing capability of TB-Zn-CP was also indicated by visualizable color changes. The Stern–Volmer quenching constant K_SV was determined to be in the order of 10³–10⁴ M⁻¹, and the sensitivity was shown to be at a nanomolar (10⁻⁹ M) level. All these results confirm that TB-Zn-CP can be a potential and practically useful polymeric sensor for differential fluorescence and visual detection of different antibiotics in water. Full article

Perovskite solar cells (PSCs) have garnered significant attention in the photovoltaic field owing to their exceptional photoelectric properties, including high light absorption, extensive carrier diffusion distance, and an adjustable band gap. Temperature is a crucial factor influencing both the preparation and performance of perovskite solar cells. The annealing temperature exerts a pronounced impact on the device structure, while the operational temperature influences carrier transport, perovskite band gap, and interface properties. This paper provides a comprehensive review of the influence of varied annealing temperatures on the hole transport layer, electron transport layer, and perovskite layer. Additionally, we present an overview of innovative annealing methods applied to perovskite materials. The effects of diverse working temperatures on the overall performance of perovskite cells are thoroughly examined and discussed in this review. In the end, different temperature conditions under ISOS testing conditions are summarized. Full article

Heterocycles, compounds featuring heteroatoms like nitrogen, sulfur, and oxygen, are integral in fields such as synthesis, pharmacology, and medicine. Among these, benzothiazoles, formed by fusing thiazole with benzene, hold significant prominence. Their unique reactivity, especially at the carbon position between nitrogen and sulfur, has sparked wide interest. Notably, 2-substituted benzothiazoles exhibit diverse biological activities, including anticonvulsant, antimicrobial, and antioxidant properties, making them valuable in drug discovery. This review unveils an array of mesmerizing methods employed by chemists to prepare these compounds using 2-aminothiophenol as one of the precursors with other varied reactants. From novel strategies to sophisticated methodologies, each section of this review provides a glimpse into the fascinating world of synthetic chemistry of 2-substituted benzothiazoles. Delving into the diverse synthetic applications of 2-substituted benzothiazoles, this paper not only enriches our understanding of their synthesis but also sparks the imagination with the possibilities for future advancements. Full article

High-temperature cooking processes like frying, baking, smoking, or drying can induce chemical transformations in conventional food ingredients, causing deteriorative modifications. These reactions, including hydrolytic, oxidative, and thermal changes, are common and can alter the food’s chemical composition. This study transformed a combination of sucrose and histidine (Su-Hi) through charring or pyrolysis. The GC-MS profiling study showed that when sucrose and histidine (Su-Hi) were exposed to high temperatures (≈240 °C), they produced carbonyl and aromatic compounds including beta-D-Glucopyranose, 1,6-anhydro (10.11%), 2-Butanone, 4,4-dimethoxy- (12.89%), 2(1H)-Quinolinone-hydrazine (5.73%), Benzenamine (6.35%), 2,5-Pyrrolidinedione, 1-[(3,4-dimethylbenzoyl)oxy]- (5.82%), Benzene-(1-ethyl-1-propenyl) (5.62%), and 4-Pyridinamine-2,6-dimethyl (5.52%). The compounds mentioned can permeate the cell membrane and contribute to the development of cell death by necrosis in human immune cells. The evidence suggests that a specific set of pyrolytic compounds may pose a risk to immune cells. This investigation reveals the complex relationship between high-temperature cooking-induced transformations, compound permeation inside the cells, and downstream cellular responses, emphasizing the significance of considering the broader health implications of food chemical contaminants. Full article