Hasil untuk "Analytical chemistry"

Milena Rmandić, Marija Rašević, Kostas Gkountanas et al.

Impurity profiling is of significant analytical and regulatory importance, particularly in the context of lifecycle quality management. A robust chaotropic chromatography method was developed for the determination of olanzapine and its two oxidative degradation products in tablets, in accordance with the ICH Q14 guideline and the principles of Analytical Quality by Design (AQbD). Risk assessment was performed using a combination of the Ishikawa diagram, CNX (Control, Noise and eXperimental) classification, and Failure Mode and Effect Analysis (FMEA). This multistep evaluation identified the critical analytical procedure parameters (APPs) as the acetonitrile content in the mobile phase, the concentration of perchloric acid in the aqueous phase, and the pH of the aqueous phase. These APPs were studied using an experimental design approach to model their effects on key analytical procedure attributes and to compute a multidimensional design space. Robust optimization supported by Monte Carlo simulations ensured compliance with predefined acceptance criteria with a probability of at least 95%. Method validation demonstrated adequate selectivity, limits of quantification of 0.75 µg/mL and 0.5 µg/mL for impurities B and D, linearity with correlation coefficients ≥0.990, accuracy of 98–102% for olanzapine and 70–130% for impurities, and repeatability with RSD ≤2% for the assay and ≤10% for impurities. The method was successfully applied to commercial tablet analysis.

A. Bond

Hon Nhien Le, Duy Khanh Nguyen, Minh Triet Dang et al.

Natural hydration shells are discovered to play an essential role in the structure and function of biomolecules (deoxyribonucleic acid, protein, and phospholipid membrane). Hydration layers are also important to the structure and property of artificial graphene-based materials. Our recent works prove that graphene-based hydrogels are supramolecular hydration structures that preserve graphene nanosheets from the restacking through hydrophobic force, van der Waals force, and π–π interaction. In this manuscript, density functional theory and high-performance computing (HPC) are used for modeling and calculating van der Waals force between graphene nanosheets in water-intercalated AB bilayer graphene structures. A layer of water molecules significantly decreases the intersheet van der Waals force. A novel hydrogel of graphene oxide–silica gel–zinc hydroxide (GO-SG-ZH) is experimentally synthesized to demonstrate the advantages of hydrated hydrogel structure in comparison with dry powder structure. The synthesis of graphene-based hydrogels is a green chemistry approach to attain extraordinary properties of graphene-based nanostructures. Analytical characterizations exhibited moisture contents, water evaporation rates, three-dimensional structures, elemental compositions, aqueous dispersibility, and antibacterial activities. Hydration shells on graphene-based nanosheets in the hydrogel increase intersheet distances to prevent the stacking of the nanostructures. Hydration layers in the GO-SG-ZH hydrogel was also lubricative for direct brush coating on polymer substrates, typically polylactide films. Interfacial adhesion of graphene-based nanosheets on polylactide substrates made the antibacterial coating stable for several application purposes. In general, supramolecular graphene-based hydrogels are bioinspired hydration structures to advance nanoscale properties and nanotechnology applications.

Brayan J. Anaya, Lina Raudone, Isabel Ureña-Vacas et al.

This study investigates the phytochemical profile, antioxidant and anti-inflammatory properties, and 3D-printing application of <i>Origanum vulgare</i> L. ssp. <i>hirtum</i> extract. The extract revealed a diverse range of phenolic compounds, with rosmarinic acid as the predominant compound (47.76%). The extract showed moderate to high lipoxygenase inhibition (IC₅₀ = 32.0 µg/mL), suggesting its potential as an anti-inflammatory agent. It also exhibited strong antioxidant activity, with hydrogen peroxide scavenging (SC₅₀ = 99.2 µg/mL) and hydroxyl radical scavenging (IC₅₀ = 64.12 µg/mL) capabilities. In cellular studies, high concentrations (50 µg/mL and 100 µg/mL) significantly decreased intracellular ROS production in Caco-2 cells (reductions exceeding 53% and 64%, respectively). Moreover, the extract suppressed NO production in LPS-stimulated J774A.1 macrophages in a concentration-dependent manner. The study also explores the incorporation of the extract into 3D-printed gummies. The gels exhibited a shear-thinning behavior, which was essential for successful extrusion-based 3D printing. The incorporation of <i>Origanum</i> extract significantly influenced the mechanical strength and compaction properties of the 3D-printed gummies before breaking (1.6-fold increase) allowing for a better mouth feeling. PXRD and FTIR analyses confirmed the amorphous nature of the 3D-printed gummies and the interaction between active ingredients and excipients utilized for printing. These findings demonstrated the potential for semisolid extrusion 3D printing at room temperature to transform a culinary herb (<i>Origanum vulgare</i> spp. <i>hirtum</i>) into a healthcare product with antioxidant and anti-inflammatory properties.

Nisa Ulfiatun, Putri Salsa Saloma, Heryanto Rudi et al.

Bisphenol A (BPA) is increasingly released into water, soil, and air, becoming an environmental pollutant. Since BPA is persistent in the environment, it remains there for a considerable amount of time and allows bioaccumulation, potentially affecting ecosystems and human health. For that reason, the detection of BPA in the environment is essential. In this study, we develop an electrochemical sensor for simple and rapid detection of BPA in a water environment. The sensor was developed using a glassy carbon electrode (GCE) modified with conductive materials. The detection of BPA was carried out based on the oxidation of BPA on modified GCE using a differential pulse voltammetry technique. The developed sensor performs acceptable analytical performance with a detection limit of 0.5 μM and sensitivity of 0.22 μA μM-1. The developed sensor also has the potency for BPA detection in water samples.

Petya Emilova Marinova, Nikola Burdzhiev, Evelina Varbanova et al.

(This paper presents the synthesis of a novel copper(II) metal complex with ethyl (2-(methylcarbamoyl)phenyl)carbamate and 3-methylquinazoline-2,4(1<i>H</i>,3<i>H</i>)-dione. The characterization of the compound was conducted through various techniques, including melting point determination, microwave plasma atomic emission spectrometry (MP-AES) for Cu, attenuated total reflection (ATR), IR, ¹H NMR, and ¹³C NMR spectroscopy. The coordination compound was obtained after mixing water solutions of the metal salt and the ligand dissolved in DMSO and water solutions of NaOH, in a metal-to-ligand-to-base ratio of 1:2:2. The ligand and the metal chloride were brought into the reaction at room temperature in DMSO and H₂O as solvents, respectively. The results indicate the successful formation of a stable mixed-ligand Cu(II) coordination compound involving N,O-donor ligands. Based on the obtained data, we assumed that the ligands are coordinated through N- and O-donor atoms. Spectroscopic data suggested that the ligand (3-methylquinazoline-2,4(1<i>H</i>,3<i>H</i>)-dione), by using (NaOH), coordinated to a metal ion as a monodentate ligand through the nitrogen atom of the NH group and ethyl (2-(methylcarbamoyl)phenyl)carbamate coordinated in a bidentate fashion through the N- and O-donor atoms of ester group. Additionally, two hydroxyl groups were bridged for two metal ions into the formed dimer structure.

Nora Bauer, Kübra Yeter-Aydeniz, George Siopsis

We present a hardware-efficient optimization scheme for quantum chemistry calculations, utilizing the Sampled Quantum Diagonalization (SQD) method. Our algorithm, optimized SQD (SQDOpt), combines the classical Davidson method technique with added multi-basis measurements to optimize a quantum Ansatz on hardware using a fixed number of measurements per optimization step. This addresses the key challenge associated with other quantum chemistry optimization protocols, namely Variational Quantum Eigensolver (VQE), which must measure in hundreds to thousands of bases to estimate energy on hardware, even for molecules with less than 20 qubits. Numerical results for various molecules, including hydrogen chains, water, and methane, demonstrate the efficacy of our method compared to classical and quantum variational approaches, and we confirm the performance on the IBM-Cleveland quantum hardware, where we find instances where SQDOpt either matches or exceeds the solution quality of noiseless VQE. A runtime scaling indicates that SQDOpt on quantum hardware is competitive with classical state-of-the-art methods, with a crossover point of 1.5 seconds/iteration for the SQDOpt on quantum hardware and classically simulated VQE with the 20-qubit H$_{12}$ molecule. Our findings suggest that the proposed SQDOpt framework offers a scalable and robust pathway for quantum chemistry simulations on noisy intermediate-scale quantum (NISQ) devices.

Deborah Bardet, Quentin Changeat, Olivia Venot et al.

Constraining the chemical structure of exoplanetary atmospheres is pivotal for interpreting spectroscopic data and understanding planetary evolution. Traditional retrieval methods often assume thermochemical equilibrium or free profiles, which may fail to capture disequilibrium processes like photodissociation and vertical mixing. This study leverages the TauREx 3.1 retrieval framework coupled with FRECKLL, a disequilibrium chemistry model, to address these challenges. The study aims to (1) assess the impact of disequilibrium chemistry on constraining metallicity and C/O ratios; (2) evaluate the role of refractory species (TiO and VO) in spectral retrievals; (3) explore consistency between transit and eclipse observations for temperature and chemical profiles; and (4) determine the effects of retrieval priors and data reduction methods. Ten hot-Jupiter atmospheres were reanalyzed using Hubble Space Telescope (HST) WFC3 data in eclipse and transit. The TauREx-FRECKLL model incorporated disequilibrium chemistry calculations with a Bayesian framework to infer atmospheric properties. The disequilibrium approach significantly altered retrieved metallicity and C/O ratios compared to equilibrium models, impacting planet formation insights. Retrievals reconciled transit and eclipse temperature profiles in deeper atmospheric layers but not in upper layers. Results were highly dependent on spectral resolution and retrieval priors, emphasizing limitations of HST data and the need for broader spectral coverage from instruments like JWST. This study demonstrates the feasibility and importance of incorporating disequilibrium chemistry in atmospheric retrievals, highlighting its potential for advancing our understanding of exoplanetary atmospheres with next-generation telescopes.

Dominik Sidler, Michael Ruggenthaler, Angel Rubio

Polaritonic chemistry has garnered increasing attention in recent years due to pioneering experimental results, which show that site- and bond-selective chemistry at room temperature is achievable through strong collective coupling to field fluctuations in optical cavities. Despite these notable experimental strides, the underlying theoretical mechanisms remain unclear. In this focus review, we highlight a fundamental theoretical link between the seemingly unrelated fields of polaritonic chemistry and spin glasses, exploring its profound implications for the theoretical framework of polaritonic chemistry. Specifically, we present a mapping of the dressed many-molecules electronic-structure problem under collective vibrational strong coupling to the spherical Sherrington-Kirkpatrick (SSK) model of a spin glass. This mapping uncovers a collectively induced instability of the intermolecular electron correlations, which could provide the long sought-after seed for significant local chemical modifications in polaritonic chemistry. Overall, the qualitative predictions made from the SSK model (e.g., dispersion effects, phase transitions, differently modified bulk and rare event properties, heating,...) agree well with available experimental observations. Our connection paves the way to incorporate, adjust and probe numerous spin glass concepts in polaritonic chemistry, such as modified fluctuation-dissipation relations, (non-equilibrium) aging dynamics, time-reversal symmetry breaking or stochastic resonances. Ultimately, the connection also offers fresh insights into the applicability of spin glass theory beyond condensed matter systems suggesting novel theoretical directions such as spin glasses with explicitly time-dependent (random) interactions.

Fotios Gkritsis, Daniel Dux, Jin Zhang et al.

We show that quantum number preserving Ansätze for variational optimization in quantum chemistry find an elegant mapping to ultracold fermions in optical superlattices. Using native Hubbard dynamics, trial ground states of molecular Hamiltonians can be prepared and their molecular energies measured in the lattice. The scheme requires local control over interactions and chemical potentials and global control over tunneling dynamics, but foregoes the need for optical tweezers, shuttling operations, or long-range interactions. We describe a complete compilation pipeline from the molecular Hamiltonian to the sequence of lattice operations, thus providing a concrete link between quantum simulation and chemistry. Our work enables the application of recent quantum algorithmic techniques, such as Double Factorization and quantum Tailored Coupled Cluster, to present-day fermionic optical lattice systems with significant improvements in the required number of experimental repetitions. We provide detailed quantum resource estimates for small non-trivial hardware experiments.

Maria Jose Colmenares, Edwin Bergin, Colette Salyk et al.

It has been proposed, and confirmed by multiple observations, that disks around low mass stars display a molecule-rich emission and carbon-rich disk chemistry as compared to their hotter, more massive solar counterparts. In this work, we present JWST Disk Infrared Spectral Chemistry Survey (JDISCS) MIRI-MRS observations of the solar-mass star DoAr 33, a low-accretion rate T Tauri star showing an exceptional carbon-rich inner disk. We report detections of H$_2$O, OH, and CO$_2$, as well as the more complex hydrocarbons, C$_2$H$_2$ and C$_4$H$_2$. Through the use of thermochemical models, we explore different spatial distributions of carbon and oxygen across the inner disk and compare the column densities and temperatures obtained from LTE slab model retrievals. We find a best match to the observed column densities with models that have carbon enrichment, and the retrieved emitting temperature and area of C$_2$H$_2$ with models that have C/O $=$ 2$-$4 inside the 500 K carbon-rich dust sublimation line. This suggests that the origin of the carbon-rich chemistry is likely due to the sublimation of carbon rich grains near the soot line. This would be consistent with the presence of dust processing as indicated by the detection of crystalline silicates. We propose that this long-lived hydrocarbon rich chemistry observed around a solar-mass star is a consequence of the unusually low M-star-like accretion rate of the central star, which lengthens the radial mixing timescale of the inner disk allowing the chemistry powered by carbon grain destruction to linger.

Austin Cheng, Cher Tian Ser, Marta Skreta et al.

Machine learning has been pervasively touching many fields of science. Chemistry and materials science are no exception. While machine learning has been making a great impact, it is still not reaching its full potential or maturity. In this perspective, we first outline current applications across a diversity of problems in chemistry. Then, we discuss how machine learning researchers view and approach problems in the field. Finally, we provide our considerations for maximizing impact when researching machine learning for chemistry.

Felix Sainsbury-Martinez, Catherine Walsh

Impacts from icy and rocky bodies have helped shape the composition of solar system objects, for example the Earth-Moon system, or the recent impact of comet Shoemaker-Levy 9 with Jupiter. It is likely that such impacts also shape the composition of exoplanetary systems. Here we investigate how cometary impacts might affect the atmospheric composition/chemistry of hot Jupiters, which are prime targets for characterisation. We introduce a parametrised cometary impact model that includes thermal ablation and pressure driven breakup, which we couple with the 1D `radiative-convective' atmospheric model ATMO, including disequilibrium chemistry. We use this model to investigate a wide range of impactor masses and compositions, including those based on observations of Solar System comets, and interstellar ices (with JWST). We find that even a small impactor (R = 2.5 km) can lead to significant short-term changes in the atmospheric chemistry, including a factor $>10$ enhancement in H$_2$O, CO, CO$_2$ abundances, and atmospheric opacity more generally, and the near complete removal of observable hydrocarbons, such as CH$_4$, from the upper atmosphere. These effects scale with the change in atmospheric C/O ratio and metallicity. Potentially observable changes are possible for a body that has undergone significant/continuous bombardment, such that the global atmospheric chemistry has been impacted. Our works reveals that cometary impacts can significantly alter or pollute the atmospheric composition/chemistry of hot Jupiters. These changes have the potential to mute/break the proposed link between atmospheric C/O ratio and planet formation location relative to key snowlines in the natal protoplanetary disc.

Mai Aish, Reem F. Alshehri, Alaa S. Amin et al.

The entrapment of the sensitive reagent 5-(2′-bromophenylazo)-6‑hydroxy-pyrimidine-2,4‑dione (BPAHPD) in a silica sol-gel thin film coated on a glass substrate has been investigated for the development of a highly sensitive and selective optode for the determination of lead ions. The fabrication of thin films requires tetraethoxysilane as a precursor, a sol-gel pH of 2.75, a water: alkoxide ratio of 5:1, and a BPAHPD concentration of 4.0 × 10–4 M. The effect of sol-gel parameters on the optode's sensing performance was investigated. The fabricated optode is utilized for lead ion detection over a dynamic range of 4.00–144 ng mL–1 with detection and quantification limits of 1.20 and 3.95 ng mL–1, respectively. It gave repeatable results with relative standard deviation (RSD) values of 1.90% and 1.15% for lead concentrations of 40.0 and 80.0 ng mL–1, respectively, and a response time of two minutes. Through capturing BPAHPD in a sol-gel matrix and appropriately modifying the structure of doped sol-gel, interference studies have determined that lead exhibits a high degree of selectivity. To ascertain total lead, Pb4+ was reduced to Pb2+ using a few drops of 6.00 M hydrochloric acid and a freshly prepared sodium azide solution of 2.50 % (w/v). The optode can be easily regenerated with 0.15 M of nitric acid solution. The optode has complete reversibility. Optode detection of lead in diverse vegetable, food, biological, water, and soil samples yielded favorable results when compared to other techniques.

Piotr Cyganowski, Anna Dzimitrowicz, Mateusz M. Marzec et al.

Abstract Nitroaromatic compounds (NACs) are key contaminants of anthropogenic origin and pose a severe threat to human and animal lives. Although the catalytic activities of Re nanostructures (NSs) are significantly higher than those of other heterogeneous catalysts containing NSs, few studies have been reported on the application of Re-based nanocatalysts for NAC hydrogenation. Accordingly, herein, catalytic reductions of nitrobenzene (NB), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), 4-nitroaniline (4-NA), and 2,4,6-trinitrophenol (2,4,6-TNP) over new Re-based heterogeneous catalysts were proposed. The catalytic materials were designed to enable effective syntheses and stabilisation of particularly small Re structures over them. Accordingly, catalytic hydrogenations of NACs under mild conditions were significantly enhanced by Re sub-nanostructures (Re-sub-NSs). The highest pseudo-first-order rate constants for NB, 4-NP, 2-NA, 4-NA, and 2,4,6-TNP reductions over the catalyst acquired by stabilising Re using bis(3-aminopropyl)amine (BAPA), which led to Re-sub-NSs with Re concentrations of 16.7 wt%, were 0.210, 0.130, 0.100, 0.180, and 0.090 min−1, respectively.

Peter Olusakin Oladoye, Timothy Oladiran Ajiboye, Wycliffe Chisutia Wanyonyi et al.

The extensive usage of malachite green (MG) dyes in the fish and dye industries cause serious water pollution, leading to catastrophic effects on living organisms and the environment. In addressing the challenges of health risks related to the use of MG, different removal strategies have been studied and developed. This review presents the recent advances and mechanistic pathways involved in ozonation, electrochemical advanced oxidation (electrooxidation), and biological removal techniques for MG. The successful applications of these techniques in decontaminating water from MG are discussed. Furthermore, combined removal techniques for enhancing MG removal and for the reduction of operation costs are presented as it was shown in some cases to be more effective than individual remediation methods.

Leila Mehrannia, Balal Khalilzadeh, Reza Rahbarghazi et al.

<i>Listeria monocytogenes</i> (L.M.) is a gram-positive bacillus with wide distribution in the environment. This bacterium contaminates water sources and food products and can be transmitted to the human population. The infection caused by L.M. is called listeriosis and is common in pregnant women, immune-deficient patients, and older adults. Based on the released statistics, listeriosis has a high rate of hospitalization and mortality; thus, rapid and timely detection of food contamination and listeriosis cases is necessary. During the last few decades, biosensors have been used for the detection and monitoring of varied bacteria species. These devices are detection platforms with great sensitivity and low detection limits. Among different types of biosensors, electrochemical biosensors have a high capability to circumvent several drawbacks associated with the application of conventional laboratory techniques. In this review article, different electrochemical biosensor types used for the detection of listeriosis were discussed in terms of actuators, bioreceptors, specific working electrodes, and signal amplification. We hope that this review will facilitate researchers to access a complete and comprehensive template for pathogen detection based on the different formats of electrochemical biosensors.

Leonardo F. Calderón, Humberto Triviño, Leonardo A. Pachón

Polaritonic chemistry has ushered in new avenues for controlling molecular dynamics. However, two key questions remain: (i) Can classical light sources elicit the same effects as certain quantum light sources on molecular systems? (ii) Can semiclassical treatments of light-matter interaction capture nontrivial quantum effects observed in molecular dynamics? This work presents a quantum-classical approach addressing issues of realizing cavity chemistry effects without actual cavities. It also highlights the limitations of the standard semiclassical light-matter interaction. It is demonstrated that classical light sources can mimic quantum effects up to the second order of light-matter interaction, provided that the mean-field contribution, symmetrized two-time correlation function, and the linear response function are the same in both situations. Numerical simulations show that the quantum-classical method aligns more closely with exact quantum molecular-only dynamics for quantum light states such as Fock states, superpositions of Fock states, and vacuum squeezed states than the conventional semiclassical approach.

S. Maes, M. Van de Sande, T. Danilovich et al.

Asymptotic Giant Branch (AGB) stars shed a significant amount of their mass in the form of a stellar wind, creating a vast circumstellar envelope (CSE). Owing to the ideal combination of relatively high densities and cool temperatures, CSEs serve as rich astrochemical laboratories. {While the chemical structure of AGB outflows has been modelled and analysed in detail for specific physical setups, there is a lack of understanding regarding the impact of changes in the physical environment on chemical abundances. A systematic sensitivity study is necessary to comprehend the nuances in the physical parameter space, given the complexity of the chemistry. This is crucial for estimating uncertainties associated with simulations and observations. In this work, we present the first sensitivity study of the impact of varying outflow densities and temperature profiles on the chemistry. With the use of a chemical kinetics model, we report on the uncertainty in abundances, given a specific uncertainty on the physical parameters. }Additionally, we analyse the molecular envelope extent of parent species and compare our findings to observational studies. Mapping the impact of differences in physical parameters throughout the CSE on the chemistry is a strong aid to observational studies.

Lillibeth Chaverra-Muñoz, Theresa Briem, Stephan Hüttel

Abstract Background The fungal sesquiterpenes Illudin M and S are important base molecules for the development of new anticancer agents due to their strong activity against some resistant tumor cell lines. Due to nonspecific toxicity of the natural compounds, improvement of the pharmacophore is required. A semisynthetic derivative of illudin S (Irofulven) entered phase II clinical trials for the treatment of castration-resistant metastatic prostate cancer. Several semisynthetic illudin M derivatives showed increased in vitro selectivity and improved therapeutic index against certain tumor cell lines, encouraging further investigation. This requires a sustainable supply of the natural compound, which is produced by Basidiomycota of the genus Omphalotus. We aimed to develop a robust biotechnological process to deliver illudin M in quantities sufficient to support medicinal chemistry studies and future preclinical and clinical development. In this study, we report the initial steps towards this goal. Results After establishing analytical workflows, different culture media and commercially available Omphalotus strains were screened for the production of illudin M.Omphalotus nidiformis cultivated in a medium containing corn steep solids reached ~ 38 mg L−1 setting the starting point for optimization. Improved seed preparation in combination with a simplified medium (glucose 13.5 g L−1; corn steep solids 7.0 g L− 1; Dox broth modified 35 mL), reduced cultivation time and enhanced titers significantly (~ 400 mg L−1). Based on a reproducible cultivation method, a feeding strategy was developed considering potential biosynthetic bottlenecks. Acetate and glucose were fed at 96 h (8.0 g L−1) and 120 h (6.0 g L−1) respectively, which resulted in final illudin M titer of ~ 940 mg L−1 after eight days. This is a 25 fold increase compared to the initial titer. Conclusion After strict standardization of seed-preparation and cultivation parameters, a combination of experimental design, empirical trials and additional supply of limiting biosynthetic precursors, led to a highly reproducible process in shake flasks with high titers of illudin M. These findings are the base for further work towards a scalable biotechnological process for a stable illudin M supply.