Hasil untuk "Analytical chemistry"

S. Armenta, S. Garrigues, M. de la Guardia

Bruno Debus, Hadi Parastar, Peter Harrington et al.

Mariusz Kluska, Joanna Jabłońska, Dorota Prukała et al.

Cytosine and its derivatives are an important research topic in the fields of bioorganic chemistry, molecular biology and medicine due to their key role in the structure and function of nucleic acids. The article provides a detailed overview of the natural occurrence of cytosine, its biosynthetic and degradation pathways in living organisms, as well as its physicochemical and chemical properties. Particular attention was paid to the biological activity and therapeutic applications of cytosine derivatives, including their use in cancer, antiviral and epigenetic therapy. The analytical section describes high-performance liquid chromatography techniques as a major tool for identifying and determining cytosine and its derivatives in biological samples. Examples of separation conditions, column selection, mobile phases and detection parameters for these compounds are presented. The article also provides chemical structures, graphs, comparative tables and an up-to-date review of the scientific literature, presenting a comprehensive overview of the topic, including biological, chemical and analytical aspects.

Saulo Alves de Souza, Gabriel Oliveira Araújo Costa, Grazielle Cabral de Lima et al.

Dobrochna Rabiej-Kozioł, Aleksandra Szydłowska-Czerniak

In the present study, methanolic extracts from rapeseed meal, an oil industry by-product, were treated with alkaline hydrolysis, acid hydrolysis, and lyophilization to enhance their antioxidant features. Antioxidant activity (AA) of the prepared rapeseed meal extracts was determined using three modified spectrophotometric methods: 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) methods. The effect of acid-hydrolyzed and lyophilized rapeseed meal extract (HLRME) at 200 ppm on the antioxidant properties of refined rapeseed oil heating at 180 °C for 24 h and French fries fried in it was estimated. Moreover, the total phenolic content (TPC) in rapeseed meal extracts, enriched rapeseed oils before and after the thermo-degradation processes, and fried French fries was analyzed. The addition of HLRME affected the oxidation stability of refined rapeseed oil heated for 8 h daily for 3 days at 180 °C by preventing an increase in the peroxide values (PV), anisidine values (<i>p</i>-AnV), TOTOX and INTOX indexes, conjugated dienes (K₂₃₂), and total polar material (TPM). However, thermal degradation generated similar amounts of conjugated trienes (K₂₆₈) in non-supplemented and supplemented rapeseed oils. Fortified rapeseed oils after each heating cycle and French fries fried in them revealed higher antioxidant properties than those prepared in refined rapeseed oils without HLRME. Results from the present study suggest that HLRME, as a potential source of natural antioxidants from oil industry by-products, can prevent the degradation of refined rapeseed oil and help improve the quality of French fries.

Priyankush Ghosh, Sambit Mishra, Shubham Dey et al.

The launch of the James Webb Space Telescope (JWST) has delivered high-quality atmospheric observations and expanded the known chemical inventory of exoplanetary atmospheres, opening new avenues for atmospheric chemistry modeling to interpret these data. Here, we present XODIAC, a fast, GPU-accelerated, one-dimensional photochemical model with a built-in equilibrium chemistry solver, an updated thermochemical database, and three chemical reaction networks. This framework enables comparative atmospheric chemistry studies, including the newly developed XODIAC-2025 network, a state-of-the-art C-H-O-N-P-S-Metals network, linking 594 species through 7,720 reactions. The other two are existing, publicly available C-H-O-N-S and C-H-O-N-S-Metals networks, from the established photochemical models VULCAN and ARGO, respectively, which are commonly used in the community. The XODIAC model has been rigorously benchmarked on the well-studied hot Jupiter HD 189733 b, with results compared against these two models. Benchmarking shows excellent agreement and demonstrates that, when the same chemical network and initial conditions are used, the numerical scheme for solving atmospheric chemistry does not significantly affect the results. We also revisited the atmospheric chemistry of HD 189733 b and performed a comparative analysis across the three networks. Sulfur chemistry shows the least variation across networks, carbon chemistry shows slightly more, and phosphorus chemistry varies the most, primarily due to the introduction of unique PHO and PN pathways comprising 390 reactions in the XODIAC-2025 network. These findings highlight XODIAC's capability to advance exoplanetary atmospheric chemistry and provide a robust framework for comparative exoplanetology.

Smik Patel, Praveen Jayakumar, Tzu-Ching Yen et al.

Quantum chemistry is among the most promising applications of quantum computing, offering the potential to solve complex electronic structure problems more efficiently than classical approaches. A critical component of any quantum algorithm is the measurement step, where the desired properties are extracted from a quantum computer. This review focuses on recent advancements in quantum measurement techniques tailored for quantum chemistry, particularly within the second quantized framework suitable for current and near-term quantum hardware. We provide a comprehensive overview of measurement strategies developed primarily for the Variational Quantum Eigensolver (VQE) and its derivatives. These strategies address the inherent challenges posed by complexity of the electronic Hamiltonian operator. Additionally, we examine methods for estimating excited states and one- and two-electron properties, extending the applicability of quantum algorithms to broader chemical phenomena. Key aspects of the review include approaches for constructing measurement operators with reduced classical preprocessing and quantum implementation costs, techniques to minimize the number of measurements required for a given accuracy, and error mitigation strategies that leverage symmetries and other properties of the measurement operators. Furthermore, we explore measurement schemes rooted in Quantum Phase Estimation (QPE), which are expected to become viable with the advent of fault-tolerant quantum computing. This review emphasizes foundational concepts and methodologies rather than numerical benchmarks, serving as a resource for researchers aiming to enhance the efficiency and accuracy of quantum measurements in quantum chemistry.

Alan Bidart, Prateek Vaish, Tilas Kabengele et al.

Quantum computing offers the promise of revolutionizing quantum chemistry by enabling the solution of chemical problems for substantially less computational cost. While most demonstrations of quantum computation to date have focused on resolving the energies of the electronic ground states of small molecules, the field of quantum chemistry is far broader than ground state chemistry; equally important to practicing chemists are chemical reaction dynamics and reaction mechanism prediction. Here, we review progress toward and the potential of quantum computation for understanding quantum chemistry beyond the ground state, including for reaction mechanisms, reaction dynamics, and finite temperature quantum chemistry. We discuss algorithmic and other considerations these applications share, as well as differences that make them unique. We also highlight the potential speedups these applications may realize and challenges they may face. We hope that this discussion stimulates further research into how quantum computation may better inform experimental chemistry in the future.

Carla Martini, Elena Bernardi, Cecilia Velino et al.

Abstract The development of innovative solutions for the conservation and the protection of historic aircraft is a recent and important issue raised in the cultural heritage field and represents the goal of the PROCRAFT (Protection and Conservation of Heritage Aircraft) project. Assessing and documenting the constituent materials as well as their degradation state is necessary to determine and understand factors inducing aluminium alloy corrosion, in order to develop tailored conservation treatments and identify effective protective coatings. The first step of the project was the identification of the constituent materials of aircraft wrecks. Al-Cu-Mg alloys—Duralumin and Super Duralumin, with a higher content of Mg—were the most employed alloys for structural and non-structural parts. These materials undergo a wide range of alterations, amongst which pitting, exfoliation and galvanic corrosion. In the present work, results of the characterisation of wrecks from a North American Republic P-47D Thunderbolt, crashed in Italy in 1945, are reported and compared to wrecks from a French Breguet 765 Sahara n°504 64-PH, built in 1958. The constituent alloys resulted to be similar to the modern 2024 and 2017A alloy. In order to assess the representativeness of these modern alloys in simulating the corrosion behaviour of the historic ones, exfoliation susceptibility (ASTM G34) as well as non-destructive and destructive electrochemical tests in 0.1 M NaCl were carried out on both historic and modern alloys. These results contributed to the selection of representative substrates for the development of protective coatings as well as to the expansion of the dataset on composition and microstructure of historic Al alloys for aircraft.

Fabian Malfent, Fabian Malfent, Martin Zehl et al.

Bacterial endophytes dwelling in medicinal plants represent an as yet underexplored source of bioactive natural products with the potential to be developed into drugs against various human diseases. For the first time, several Streptomyces spp. were isolated from the rare and endangered traditional medicinal plant Leontopodium nivale ssp. alpinum, also known as Edelweiss. In the search for novel natural products, nine endophytic Streptomyces spp. from Edelweiss were investigated via genome sequencing and analysis, followed by fermentation in different media and investigation of secondary metabolomes. A total of 214 secondary metabolite biosynthetic gene clusters (BGCs), of which 35 are presumably unique, were identified by the bioinformatics tool antiSMASH in the genomes of these isolates. LC-MS analyses of the secondary metabolomes of these isolates revealed their potential to produce both known and presumably novel secondary metabolites, whereby most of the identified molecules could be linked to their cognate BGCs. This work sets the stage for further investigation of endophytic streptomycetes from Edelweiss aimed at the discovery and characterization of novel bioactive natural products.

Lily Annisa, Suci Hanifah, Putri Setiani

Background: Phlebitis is an inflammatory process that is characterized by inflamed venous endothelial cells. Vesicant medications are found to be one of the causes of phlebitis, especially in pediatric patients. Objective: To investigate the correlation between the use of vesicant medications and phlebitis incidence. Material and Methods: The study was descriptive observational conducted over the period of June–July 2022 in a pediatric ward. The inclusion criteria were male or female pediatric inpatients, aged 1 month–18 years, and receiving medication via intravenous infusion for >24 hours. The data obtained were then analyzed for correlations by using bivariate and multivariate analysis. Results and Conclusion: A total of 174 patients met the inclusion criteria; 27.6% experienced phlebitis, and 37.9% received vesicant medications. The most frequently used vesicant medications in the pediatric ward was gentamicin (74.24%). The use of vesicants and administration of >3 intravenous drugs showed statistically significant results associated with the incidence of phlebitis, with RR: 4.17 (P < 0.001; CI = 2.1–8.3) and RR = 2.6 (P = 0.012; CI = 1.2–5.5), respectively. The multivariate test results showed that the use of vesicants was a risk factor for phlebitis, with OR = 4.41 (P < 0.001; CI = 2.0–9.7). The use of vesicants is associated with the incidence of phlebitis in a pediatric inpatient ward.

Rong Ma, Donghui Quan, Yan Zhou et al.

Sulfur chemistry in the formation process of low-mass stars and planets remains poorly understood. The protoplanetary disks (PPDs) are the birthplace of planets and its distinctive environment provides an intriguing platform for investigating models of sulfur chemistry. We analyzed the ALMA observations of CS 7-6 transitions in the HD 163296 disk and perform astrochemical modeling to explore its sulfur chemistry. We simulated the distribution of sulfur-containing molecules and compared it with observationally deduced fractional column densities. We have found that the simulated column density of CS is consistent with the observationally deduced fractional column densities, while the simulated column density of C$_2$S is lower than the observationally deduced upper limits on column densities. This results indicate that we have a good understanding of the chemical properties of CS and C$_2$S in the disk. We also investigated the influence of the C/O ratio on sulfur-containing molecules and found that the column densities of SO, SO$_2$, and H$_2$S near the central star are dependent on the C/O ratio. Additionally, we found that the $N$[CS]/$N$[SO] ratio can serve as a promising indicator of the disk's C/O ratio in the HD 163296. Overall, the disk of HD 163296 provides a favorable environment for the detection of sulfur-containing molecules.

Neeharika R Soorgani, Himanshu Khashu, Richa Agrawal et al.

Introduction: Periodontitis is an inflammatory disease of microbial origin. Local drug delivery agents help reduce subgingival microflora. Achyranthes aspera is a medicinal herb with antimicrobial, antioxidant, anti-inflammatory, and wound-healing properties. Materials and Methods: A split-mouth study was conducted, in which 60 sites were included. Clinical parameters included measurements of probing depth (PD), gingival index, and clinical attachment level (CAL). Gingival crevicular fluid (GCF) samples were collected, followed by microbiological analysis of Porphyromonas Gingivalis. Clinical and microbiological parameters were recorded at baseline and after 3 months. Statistical analysis was done using the Statistical Package of Social Science (SPSS Version 22; Chicago Inc., USA). Result: At 3 months, Group A resulted in greater mean reductions in clinical parameters: PD (3.77) as compared to Group B (5.23), and also greater mean CAL gain (3.18) in group A as compared to Group B (5.16). Group A also showed a significant reduction in the number of sites harboring periodontopathogens as compared to Group B. Conclusion: A. aspera gel can be used as a nonsurgical local drug delivery agent in patients with chronic periodontitis as an effective adjunct to SRP.

Said A. Hassan, Reham A. Fekry, Yasmin M. Fayez et al.

Abstract The presence of minor components represents a challenging problem in spectrophotometric analysis of pharmaceuticals. If one component has a low absorptivity or present in a low concentration compared to the other components, this will hinder its quantitation by spectrophotometric methods. Continuous Wavelet Transform (CWT) as a signal processing technique was utilized to figure out a solution to such a problem. A comparative study was established between traditional derivative spectrophotometry (Numerical Differentiation, ND) and CWT to indicate the advantages and limitations of each technique and possibility of solving the problem of minor components. A mixture of ibuprofen (IBU) and phenylephrine (PHE) with its degradation products forming a ternary mixture was used for comparing the two techniques. The two techniques were applied on raw spectral data and on ratio spectra data resulting in four methods, namely ND, CWT, Derivative Ratio-Zero Crossing (DRZC) and Continuous Wavelet Transform Ratio-Zero Crossing (CWTR-ZC) methods. By comparing the results in laboratory prepared mixtures, CWT technique showed advantages in analysis of mixtures with minor components than ND. The proposed methods were validated according to the ICH guideline Q2(R1), where their linearity was established with correlation coefficient ranging from 0.9995 to 0.9999. The linearity was in the range 3–40 μg/mL for PHE in all methods, while for IBU it was 20–180 and 30–180 μg/mL in CWT and ND methods, respectively. The CWT methods were applied for quantitative determination of the drugs in their dosage form showing the ability of the methods to quantitate minor components in pharmaceutical formulations.

Safiya J. Best, Santana Thomas, Nancy Flynn et al.

Sexual assault kits are the standard method for collecting and preserving sexual assault evidence. During the sexual assault examination, swabs are commonly used to collect bodily fluids as sexual assault evidence from the vagina, anus, mouth, and skin. The type of fiber swab used during collection can greatly influence the recovery of the substrate. In cases where lubricant residue may be present, it would be useful to identify the swab type that would be the most efficient in the collection of lubricant residues. In this study, four types of swabs with different fibers (i.e., cotton, polyester, rayon, and foam) with sexual lubricants present, were extracted in various solvents. The extracts were analyzed using attenuated total reflectance Fourier-transform infrared (ATR-FTIR) and Raman spectroscopy. The Pearson correlation coefficient (PCCs) test was applied to determine a pairwise comparison between swab lube extracts and the standard lubricant reference. Visual comparisons of the lubricant reference, blank fiber swab, and the fiber lubricant extract were used to determine peak overlap, significance, and matrix interference.

Ana Carolina de Lima, Luciana R. Brandao, Bruno G. Botelho et al.

Gas chromatography–mass spectrometry (GC–MS), physicochemical and microbiological analyses, sensory descriptive evaluation, and multivariate analyses were applied to evaluate the efficiencies of microfiltration and pasteurization processes during the shelf life of beer. Samples of microfiltered and pasteurised beer were divided into fresh and aged groups. A forced ageing process, which consisted of storing fresh samples at 55° C for 6 days in an incubator and then keeping them under ambient conditions prior to analysis, was applied. Physicochemical analysis showed that both microfiltered and pasteurised samples had a slight variation in apparent extract, pH, and bitterness. The samples that underwent heat treatment had lower colour values compared with those that were microfiltered. Chromatographic peak areas of vicinal diketones increased in both fresh and aged samples. The results of the microbiological analysis revealed spoilage lactic acid bacteria (<i>Lactobacillus</i>) and yeasts (<i>Saccharomyces</i> and <i>non-Saccharomyces)</i> in fresh microfiltered samples. In the GC–MS analysis, furfural, considered by many authors as a heat indicator, was detected only in samples that underwent forced ageing and not in samples that were subjected to thermal pasteurisation. Finally, sensory analysis found differences in the organoleptic properties of fresh microfiltered samples compared with the rest of the samples.

Antoine Marie, Abdallah Ammar, Pierre-François Loos

We provide an in-depth examination of the $GW$ approximation of Green's function many-body perturbation theory by detailing both its theoretical and practical aspects in the realm of quantum chemistry. First, the quasiparticle context is introduced before delving into the derivation of Hedin's equations. From these, we explain how to derive the well-known $GW$ approximation of the self-energy. In a second time, we meticulously explain each step involved in a $GW$ calculation and what type of physical quantities can be computed. To illustrate its versatility, we consider two contrasting systems: the water molecule, a weakly correlated system, and the carbon dimer, a strongly correlated system. Each stage of the process is thoroughly detailed and explained alongside numerical results and illustrative plots. We hope that the contribution will facilitate the dissemination and democratization of Green's function-based formalisms within the computational and theoretical quantum chemistry community.

G. Esplugues, M. Rodríguez-Baras, D. San Andrés et al.

Within the project Evolution of Chemistry in the envelope of HOt corinoS (ECHOS), we present a study of sulphur chemistry in the envelope of the Class 0 source B335 through observations in the spectral range 7, 3, and 2 mm. We have modelled observations assuming LTE and LVG approximation. We have also used the code Nautilus to study the time evolution of sulphur species. We have detected 20 sulphur species with a total gas-phase S abundance similar to that found in the envelopes of other Class 0 objects, but with significant differences in the abundances between sulphur carbon chains and sulphur molecules containing oxygen and nitrogen. Our results highlight the nature of B335 as a source especially rich in sulphur carbon chains unlike other Class 0 sources. The low presence or absence of some molecules, such as SO and SO+, suggests a chemistry not particularly influenced by shocks. We, however, detect a large presence of HCS+ that, together with the low rotational temperatures obtained for all the S species (<15 K), reveals the moderate or low density of the envelope of B335. We also find that observations are better reproduced by models with a sulphur depletion factor of 10 with respect to the sulphur cosmic elemental abundance. The comparison between our model and observational results for B335 reveals an age of 10$^4$$<$t$<$10$^5$ yr, which highlights the particularly early evolutionary stage of this source. B335 presents a different chemistry compared to other young protostars that have formed in dense molecular clouds, which could be the result of accretion of surrounding material from the diffuse cloud onto the protostellar envelope of B335. In addition, the analysis of the SO2/C2S, SO/CS, and HCS+/CS ratios within a sample of prestellar cores and Class 0 objects show that they could be used as good chemical evolutionary indicators of the prestellar to protostellar transition.

Mary N. Boyden, Elyse M. Kleist, Courtney K. Asztalos et al.

Abstract A database was constructed of 134 reference plastic samples and their Raman spectra to aid in the rapid and accurate identification of the polymer composition of mid-twentieth century plastic purses and their component parts from the Plastics Artifacts Collection at Syracuse University Libraries. Work began by making and testing the database, which led to the determination that matching artifact spectra to reference sample spectra worked well for artifact spectra having signal-to-noise ratios down to 30:1. This finding allowed for using reduced laser power as necessary to protect delicate and pigmented artifacts. These studies enabled the definitive chemical identification of seven selected artifacts, showing that the majority are composed of single plastics including polystyrene, poly(methyl methacrylate), or cellulose acetate. However, it was discovered that one of the purses was composed of both poly(methyl methacrylate) and cellulose acetate. The compositions of three artifacts of unknown composition were discovered, corrections to the existing records were made for three other artifacts, and the composition of one artifact was confirmed. This decisive study will contribute to the archival processing and preservation of these artifacts.

Korf Nathalie, Mählitz Paul Martin, Rotter Vera Susanne

An improved management of secondary raw materials (SRM) is a crucial contribution for a circular economy and necessitates knowledge about the composition of wastes and SRM. However, this information is scarce and has to be determined with chemical analysis (CA). CA of SRM faces challenges, which can be approached by using round robin tests (RRT) to identify deviations from the “true value” of an element/molecule content. An RRT is a testing approach, which involves multiple labs to analyze one or more samples and evaluates the lab results with regard to the goal of the RRT. This article presents a systematic literature review and investigates which purposes and which performance parameters (PP) are commonly applied in RRT of SRM. The examined literature shows that the two main purposes applied are assessment of method performance and assessment of lab performance. PP can be categorized into trueness performance parameters (TPP; assessing the deviation of a value from a reference value) and precision performance parameters (PPP; describing the variability of a data set). The main TPP identified are z score and relative deviation, the main PPP identified are standard deviation and relative standard deviation. These results offer the conclusions that RRT can be used as a bespoke method to deal with analytical effects and that the selection of PP for an RRT could be based on simplicity.