Chemical Characterization Research Articles

Non-negative matrix factorization-aided phase unmixing and trace element quantification of STEM-EDXS data

Energy-dispersive X-ray spectroscopy (EDXS) mapping with a scanning transmission electron microscope (STEM) is commonly used for chemical characterization of materials. However, STEM-EDXS quantification becomes challenging when the phases constituting the sample under investigation share common elements and overlap spatially. In this paper, we present a methodology to identify, segment, and unmix phases with a substantial spectral and spatial overlap in a semi-automated fashion through combining non-negative matrix factorization with a priori knowledge of the sample. We illustrate the methodology using a sample taken from an electron beam-sensitive mineral assemblage representing Earth's deep mantle. With it, we retrieve the true EDX spectra of the constituent phases and their corresponding phase abundance maps. It further enables us to achieve a reliable quantification for trace elements having concentration levels of ∼100 ppm. Our approach can be adapted to aid the analysis of many materials systems that produce STEM-EDXS datasets having phase overlap and/or limited signal-to-noise ratio (SNR) in spatially-integrated spectra.

Low temperature catalytic activity of molybdenum promoted two-dimensional boron nitride in propane oxidative dehydrogenation reaction

The catalytic oxidation dehydrogenation of propane to propylene, achieved at low temperatures and with high selectivity on catalysts supported by non-noble metals, exhibits significant potential for a wide range of applications. The performance of boron-based catalysts in ODHP is remarkable; however, there is a dearth of research on their low-temperature range performance. The present study employed a straightforward impregnation method to synthesize a range of Mo/h-BN-γ-Al2O3 catalysts with varying molybdenum loadings, focusing on the comparison between commercial h-BN and h-BN-γ-Al2O3 mixed support. The Mo/h-BN-γ-Al2O3 catalyst demonstrates remarkable low-temperature ODHP activity, with an initial conversion rate of 2.36 % and a propylene selectivity of 96 % at a reaction temperature of 260 ℃, exhibiting good stability over 50 h, the catalytic performance of Mo/h-BN-γ-Al2O3 in the low-temperature range surpasses that of commercial h-BN by a significant margin. Comparative experiments, along with physical and chemical characterization techniques, demonstrate that the incorporation of an appropriate quantity of Mo enhances the catalyst's acidity and redox capability. Furthermore, the synergistic effect between MoOx and BOx promotes low-temperature ODHP. The mechanism underlying the catalyst's low-temperature reaction was investigated using in-situ infrared spectroscopy technology.

Environmental assessment of phosphogypsum: A comprehensive geochemical modeling and leaching behavior study

Understanding the variations in the geochemical composition of phosphogypsum (PG) destined for storage or valorization is crucial for assessing the safety and operational efficacy of waste management. The present study aimed to investigate the environmental behavior of PG using different leaching tests and to evaluate its geochemical behavior using geochemical modeling. Regarding the chemical characterization, the PG samples were predominantly composed of Ca (23.03–23.35 wt%), S (17.65–17.71 wt%), and Si (0.75–0.82 wt%). Mineralogically, the PG samples were primarily composed of gypsum (94.2–95.9 wt%) and quartz (1.67–1.76 wt%). Moreover, the automated mineralogy revealed the presence of apatite, fluorine and malladrite phases. The overall findings of the leaching tests showed that PG could be considered as non-hazardous material according to US Environmental Protection Agency limitations. However, a high leachability of elements at a L/S of 2 under acidic conditions ([Ca] = 166.52–199.87 mg/L, [S] = 207.9–233.59 mg/L, [F] = 248.62–286.65 mg/L) is observed. The weathering cell test revealed a considerable cumulative concentration over 90 days indicating potential adverse effects on the nearby environment (S: 8000 mg/kg, F: 3000 mg/kg, P: 700 mg/kg). Based on these results, it could be estimated that the surface storage of PG could have a serious impact on the environment. In this context, a simulation model was developed based on weathering cell results showed encouraging results for treating PG leachate using CaO before its disposal. Additionally, PHREEQC was used to analyze the speciation of major elements and calculate mineral phase saturation indices in PG leaching solutions. The findings revealed pH-dependent speciation for Ca, S, P, and F. The study identified gypsum, anhydrite, and bassanite as the key phases governing the dissolution of these elements.

Chemical Characterization of the Essential Oil Compositions of Mentha spicata and M. longifolia ssp. cyprica from the Mediterranean Basin and Multivariate Statistical Analyses.

This present study aims to characterize the essential oil compositions of the aerial parts of M. spicata L. and endemic M. longifolia ssp. cyprica (Heinr. Braun) Harley by using GC-FID and GC/MS analyses simultaneously. In addition, it aims to perform multivariate statistical analysis by comparing with the existing literature, emphasizing the literature published within the last two decades, conducted on both species growing within the Mediterranean Basin. The major essential oil components of M. spicata were determined as carvone (67.8%) and limonene (10.6%), while the major compounds of M. longifolia ssp. cyprica essential oil were pulegone (64.8%) and 1,8-cineole (10.0%). As a result of statistical analysis, three clades were determined for M. spicata: a carvone-rich chemotype, a carvone/trans-carveol chemotype, and a pulegone/menthone chemotype, with the present study result belonging to the carvone-rich chemotype. Carvone was a primary determinant of chemotype, along with menthone, pulegone, and trans-carveol. In M. longifolia, the primary determinants of chemotype were identified as pulegone and menthone, with three chemotype clades being pulegone-rich, combined menthone/pulegone, and combined menthone/pulegone with caryophyllene enrichment. The primary determinants of chemotype were menthone, pulegone, and caryophyllene. The present study result belongs to pulegone-rich chemotype.

Microanalytical investigation of brazilian coat of arms paintings on paper

Heraldry in Latin American art of the twentieth century can be considered rare. In this context, the material composition of coat of arms paintings on paper attributed to the Brazilian painter José Wasth Rodrigues is investigated for the first time using a microanalytical approach. Microsamples from 5 municipal coats of arms dated 1932 were analysed using Raman microscopy, Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR), and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). SEM-EDS results revealed the artist's choice of using metallic aluminium and brass in the representation of silver and gold colours, respectively. Raman microscopy analyses showed the use of traditional inorganic pigments, such as ultramarine blue, indigo, Prussian blue, yellow chromates and vermillion. In contrast, the results showed that the painting with an unusual signature attributed to the artist (W. instead of J.W.R, commonly found) contains synthetic organic dyes Orange 5, Red 53, and Yellow 1 (introduced in the 1900s). This discovery raised hypothesis of questioning authorship for this particular painting. ATR-FTIR analysis of a paint fragment from one painting confirmed the use of gum arabic as a binder. ATR-FTIR analyses of efflorescences collected from a blue paint layer of a particular coat of arms suggest protein and lipid content, raising suspicion of either the use of the tempera technique in this particular paint or remains of a past microorganism activity. Robust information was obtained on the chemical characterization of the coat of arms, enhancing comprehension of the painting techniques employed by the artist and providing insight into the production of heraldic art in Brazil at the beginning of the 20th-century.

Phytochemical, In Vitro, In Vivo, and In Silico Research on the Extract of Ajuga chamaepitys (L.) Schreb.

The present study focuses on the chemical characterization of a dry extract obtained from the species Ajuga chamaepitys (L.) Schreb, evaluating its antioxidant properties, toxicity, and in silico profile. Quantitative analysis of the dry extract revealed a notable amount of phytochemical compounds: 59.932 ± 21.167 mg rutin equivalents (mg REs)/g dry weight, 45.864 ± 4.434 mg chlorogenic acid equivalents (mg ChAEs)/g dry weight and, respectively, 83.307 ± 3.989 mg tannic acid equivalents (TAEs)/g dry weight. By UHPLC-HRMS/MS, the following were quantified as major compounds: caffeic acid (3253.8 μg/g extract) and kaempherol (3041.5 μg/g extract); more than 11 types of polyphenolic compounds were quantified (genistin 730.2 μg/g extract, naringenin 395 μg/g extract, apigenin 325.7 μg/g extract, galangin 283.3 μg/g extract, ferulic acid 254.3 μg/g extract, p-coumaric acid 198.2 μg/g extract, rutin 110.6 μg/g extract, chrysin 90.22 μg/g extract, syringic acid 84.2 μg/g extract, pinocembrin 32.7 μg/g extract, ellagic acid 18.2 μg/g extract). The antioxidant activity was in accordance with the amount of phytochemical compounds: IC50DPPH = 483.6 ± 41.4 µg/mL, IC50ABTS•+ = 127.4 ± 20.2 µg/mL, and EC50FRAP = 491.6 ± 2 µg/mL. On the larvae of Artemia sp., it was found that the extract has a low cytotoxic action. In silico studies have highlighted the possibility of inhibiting the activity of protein kinases CDK5 and GSK-3b for apigenin, galangin, and kaempferol, with possible utility for treating neurodegenerative pathologies and neuropathic pain. Further studies are warranted to confirm the predicted molecular mechanisms of action and to further investigate the therapeutic potential in animal models of neurological disorders.

Oxidation of Supported Amines for CO2 Direct Air Capture: Assessing Impact on Physical Properties and Mobility via NMR Relaxometry

AbstractAminopolymer‐based adsorbents are commonly investigated for CO2 direct air capture (DAC). In the presence of high temperature and oxygen, which can occur during adsorption‐regeneration cycles, oxidative degradation can significantly reduce adsorbent lifetime. Degradation is typically measured using adsorption performance metrics or chemical characterization. This work demonstrates that the polymer's physical properties, as measured via NMR relaxometry and differential scanning calorimetry, can be used to quantitatively track degradation. The extent of oxidation of an alumina‐poly(ethylenimine) sample, measured by reductions in amine efficiency, is correlated with proton T2 relaxation times. We hypothesize that T2 relaxation accurately tracks oxidative degradation in aminopolymers due to the reduction in polymer mobility occurring during the oxidation process. The ability to use NMR relaxometry as a non‐invasive technique to probe degradation was demonstrated on a 1‐inch square‐channel monolith adsorbent exposed to actual DAC service conditions. This highlights the potential for relaxometry to evaluate the state of the adsorbent accurately and rapidly compared to typical analytical methods.This article is protected by copyright. All rights reserved

Pt–Mo/MWCNT catalysts for desulfurization of extra-heavy crude oil at low temperature

AbstractPt–Mo nanoparticles supported by MWCNT were synthesized by wet impregnation and applied to desulfurize extra-heavy crude oil. Structural, morphological, and chemical characterizations confirmed uniform dispersion of Pt and Mo on MWCNT surfaces. The Pt–Mo nanoparticles had crystallite sizes ranging from 1.7 to 28 nm. The catalysts were used in the aquathermolysis of UTSIL crude oil, showing good stability and activity. Sulfur was reduced by 50% at 50°C and 80% at 100°C. FT-IR spectroscopy revealed the formation of hydrogenated aromatic rings and a decrease in sulfonic groups during desulfurization. Graphical abstract

Açaí (Euterpe oleracea Mart.) Seed Oil and Its Nanoemulsion: Chemical Characterisation, Toxicity Evaluation, Antioxidant and Anticancer Activities.

This study explores a nanoemulsion formulated with açaí seed oil, known for its rich fatty acid composition and diverse biological activities. This study aimed to characterise a nanoemulsion formulated with açaí seed oil and explore its cytotoxic effects on HeLa and SiHa cervical cancer cell lines, alongside assessing its antioxidant and toxicity properties both in vitro and in vivo. Extracted from fruits sourced in Brazil, the oil underwent thorough chemical characterization using gas chromatography-mass spectrometry. The resulting nanoemulsion was prepared and evaluated for stability, particle size, and antioxidant properties. The nanoemulsion exhibited translucency, fluidity, and stability post centrifugation and temperature tests, with a droplet size of 238.37, PDI -9.59, pH 7, and turbidity 0.267. In vitro assessments on cervical cancer cell lines revealed antitumour effects, including inhibition of cell proliferation, migration, and colony formation. Toxicity tests conducted in cell cultures and female Swiss mice demonstrated no adverse effects of both açaí seed oil and nanoemulsion. Overall, açaí seed oil, particularly when formulated into a nanoemulsion, presents potential for cancer treatment due to its bioactive properties and safety profile.

Trifluoromethylation of 2D Transition Metal Dichalcogenides: A Mild Functionalization and Tunable p‐Type Doping Method

AbstractChemical modification is a powerful strategy for tuning the electronic properties of 2D semiconductors. Here we report the electrophilic trifluoromethylation of 2D WSe2 and MoS2 under mild conditions using the reagent trifluoromethyl thianthrenium triflate (TTT). Chemical characterization and density functional theory calculations reveal that the trifluoromethyl groups bind covalently to surface chalcogen atoms as well as oxygen substitution sites. Trifluoromethylation induces p‐type doping in the underlying 2D material, enabling the modulation of charge transport and optical emission properties in WSe2. This work introduces a versatile and efficient method for tailoring the optical and electronic properties of 2D transition metal dichalcogenides.

Microplastics suspended in dust from different indoor environments in Barranquilla, Colombia: Predominant microparticles?

Considering that microplastics (MPs) are classified as ubiquitous pollutants, that air quality affects human health, and that people remain indoors most of the time, the need has arisen to evaluate the exposure to MPs within the suspended dust in indoor environments. With this objective, the present study carried out passive sampling to analyze the precipitation of microparticles in some indoor residential environments (2 apartments) and workplaces (an office, a pastry shop, a gift shop, and a paint shop) in Barranquilla, Colombia. The quantification and physical characterization of microparticles were carried out under a stereomicroscope, and the chemical characterization was carried out by infrared microspectroscopy (μFTIR). The highest average concentration of MPs in the apartments was found in the air-conditioned rooms (1.1 × 104 MP/m2/day), and concerning the workplaces, the gift shop and the paint shop were the spaces with a higher proportion of MPs (6.0–6.1 × 103 MP/m2/day), with polyesters being the main synthetic polymers, but being semi-synthetic particles the predominant among the samples. Regarding its morphology, fibers were the most abundant shape (>90%), grouping mainly in the 1000–5000 μm range, while the few fragments found were mostly grouped below 50 μm. Exposure by inhalation of MPs in adults was estimated between 1.7 × 102–1.6 × 103 MP/kg/day, while by ingestion it ranged between 2.7 × 102–2.4 × 103 MPs/kg/day. On the other hand, within our research, a significant presence of non-plastic microparticles was found, which reached up to 69% in analyzed samples, corresponding mainly to cotton and cellulose, so we suggest that these should also be included in future studies that aim to estimate potential health implications from exposure to suspended micropollutants.

Chemical Characterization and Effect of a Lactobacilli-Postbiotic on Streptococcus mutans Biofilm In Vitro.

Postbiotic is the term used to define the soluble factors, metabolic products, or byproducts released by live probiotic bacteria or after its lysis. The objective of this study was to carry out the chemical characterization of the postbiotic of Lacticaseibacillus rhamnosus LR-32 and to evaluate its in vitro effect on the development of the Streptococcus mutans biofilm. After the cultivation of the probiotic strain, the postbiotic was extracted by centrifuging the culture and filtering the supernatant. This postbiotic was characterized by using gas chromatography coupled with mass spectrometry (GC-MS), and then it was used to determine the growth inhibition of S. mutans in its planktonic form; additionally, its effects on the following parameters in 48 h biofilm were evaluated: viable bacteria, dry weight, and gene expression of glucosyltransferases and VicR gene. The control group consisted of the biofilm without any treatment. A paired t-test was performed for statistical analysis, with the p-value set at 5%. Seventeen compounds of various chemical classes were identified in the postbiotic, including sugars, amino acids, vitamins, and acids. The treatment with the postbiotic led to an inhibition of the growth of S. mutans in its planktonic form, as well as a decrease in the number of viable bacteria, reduction in dry weight, and a negative regulation of the gene expression of gtfB, gtfC, gtfD, and vicR in its biofilm state, compared with the nontreated group (p < 0.05). The postbiotic of L. rhamnosus impaired the development of S. mutans biofilm.

Trifluoromethylation of 2D Transition Metal Dichalcogenides: A Mild Functionalization and Tunable p-Type Doping Method.

Chemical modification is a powerful strategy for tuning the electronic properties of 2D semiconductors. Here we report the electrophilic trifluoromethylation of 2D WSe2 and MoS2 under mild conditions using the reagent trifluoromethyl thianthrenium triflate (TTT). Chemical characterization and density functional theory calculations reveal that the trifluoromethyl groups bind covalently to surface chalcogen atoms as well as oxygen substitution sites. Trifluoromethylation induces p-type doping in the underlying 2D material, enabling the modulation of charge transport and optical emission properties in WSe2. This work introduces a versatile and efficient method for tailoring the optical and electronic properties of 2D transition metal dichalcogenides.

Comprehensive characterization of Epimedium-Rhizoma drynariae herb pair in rat plasma, urine, and feces metabolic profiles by UHPLC-Q-Orbitrap HRMS combined with diagnostic extraction strategy and multicomponent pharmacokinetic study by UHPLC-MS/MS.

Epimedium-Rhizoma drynariae (EP-RD) was a well-known herb commonly used to treat bone diseases in traditional Chinese medicine. Nevertheless, there was incomplete pharmacokinetic behavior, metabolic conversion and chemical characterization of EP-RD in vivo. Therefore, this study aimed to establish metabolic profiles combined with multicomponent pharmacokinetics to reveal the in vivo behavior of EP-RD. Firstly, the diagnostic product ions (DPIs) and neutral losses (NLs) filtering strategy combined with UHPLC-Q-Orbitrap HRMS for the in vitro chemical composition of EP-RD and metabolic profiles of plasma, urine, and feces after oral administration of EP-RD to rats were proposed to comprehensively characterize the 47 chemical compounds and the 97 exogenous in vivo (35 prototypes and 62 metabolites), and possible biotransformation pathways of EP-RD were proposed, which included phase I reactions such as hydrolysis, hydrogenation, dehydrogenation, hydroxylation, dehydroxylation, isomerization, and demethylation and phase II reactions such as glucuronidation, acetylation, methylation, and sulfation. Moreover, a UHPLC-MS/MS quantitative approach was established for the pharmacokinetic analysis of seven active components: magnoflorine, epimedin A, epimedin B, epimedin C, icariin, baohuoside II, and icariin II. Results indicated that the established method was reliably used for the quantitative study of plasma active ingredients after oral administration of EP-RD in rats. Compared to oral EP alone, the increase in area under curves and maximum plasma drug concentration (P < 0.05). This study increased the understanding of the material basis and biotransformation profiles of EP-RD in vivo, which was of great significance in exploring the pharmacological effects of EP-RD.

Dan-shen Yin promotes bile acid metabolism and excretion to prevent atherosclerosis via activating FXR/BSEP signaling pathway

Ethnopharmacological relevanceDan-shen Yin (DSY), a traditional prescription, has been demonstrated to be effective in decreasing hyperlipidemia and preventing atherosclerosis (AS), but its mechanism remains unknown. We hypothesized that DSY activates farnesoid X receptor (FXR) to promote bile acid metabolism and excretion, thereby alleviating AS. Aim of the studyThis study was designed to explore whether DSY reduces liver lipid accumulation and prevents AS by activating FXR and increasing cholesterol metabolism and bile acid excretion. Materials and methodsThe comprehensive chemical characterization of DSY was analyzed by UHPLC-MS/MS. The AS models of ApoE−/− mice and SD rats was established by high-fat diet and high-fat diet combined with intraperitoneal injection of vitamin D3, respectively. The aortic plaque and pathological changes were used to evaluate AS. Lipid levels, H&E staining and oil red O staining were used to evaluate liver lipid accumulation. The cholesterol metabolism and bile acid excretion were evaluated by enzyme-linked immunosorbent assay, UPLC-QQQ/MS. In vitro, the lipid and FXR/bile salt export pump (BSEP) levels were evaluated by oil red O staining, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting. ResultsA total of 36 ingredients in DSY were identified by UPLC-MS/MS analysis. In vivo, high-dose DSY significantly inhibited aortic intimal thickening, improved arrangement disorder, tortuosity, and rupture of elastic fibers, decreased lipid levels, and reduced the number of fat vacuoles and lipid droplets in liver tissue in SD rats and ApoE−/− mice. Further studies found that high-dose DSY significantly reduced liver lipid and total bile acids levels, increased liver ursodeoxycholic acid (UDCA) and other non-conjugated bile acids levels, increased fecal total cholesterol (TC) levels, and augmented FXR, BSEP, cholesterol 7-alpha hydroxylase (CYP7A1), ATP binding cassette subfamily G5/G8 (ABCG5/8) expression levels, while decreasing ASBT expression levels. In vitro studies showed that DSY significantly reduced TC and TG levels, as well as lipid droplets, while also increasing the expression of ABCG5/8, FXR, and BSEP in both HepG2 and Nr1h4 knockdown HepG2 cells. ConclusionThis study demonstrated that DSY promotes bile acid metabolism and excretion to prevent AS by activating FXR. For the prevent of AS and drug discovery provided experimental basis.

A comparative study of gelatin-based nanofiber and sponge wound dressings

Gelatin is a collagen-derived biopolymer with high biocompatibility, commonly used in the production of wound dressing materials. Gelatin-based wound dressings, obtained through different processing methods, come with their own advantages and disadvantages depending on their physical structure. In this study, the effects of gelatin wound dressing materials with two different morphologies on wound healing are investigated in detail. The study investigated that the preparation of gelatin-based wound dressing materials using two different methods, followed by their chemical characterization and examination of their effects on biocompatibility and wound healing. To comprehend the impact of nanofiber structure and porous sponge structure on the wound healing process, the chemical structure of the prepared wound dressings was analyzed using Fourier Transform Infrared Spectrophotometer (FTIR). The morphological structure was visualized through Scanning Electron Microscope (SEM), the thermal properties were determined using Thermogravimetric Analyzer (TGA) and Differential Scanning Calorimeter (DSC). Additionally, the in vivo wound healing effects of gelatin-based wound dressings with different structures were evaluated through macroscopic observation and histological analysis in a dorsal region wound-healing rat model, monitored for 21 days. It was observed that wound healing materials with desired nanofiber and porous sponge structures were successfully obtained based on the SEM analysis. The gelatin nanofiber dressing showed a randomly oriented, bead-free, and smooth morphology with an average fiber diameter of approximately 1250 ± 0.35 nm, while the crosslinked gelatin sponge dressing had pore sizes ranging from 20 to 160 μm, and interconnected pore structures. The chemical structure remained unaltered according to FTIR graphs and these results were further supported by DSC and TGA graphs. Results from in vitro biocompatibility studies indicated that the wound dressing materials were biologically compatible, non-toxic, and did not cause irritation or sensitivity to the skin. Regarding in vivo analysis, it was determined that gelatin dressing materials were functional in the wound healing process, without the use of any auxiliary materials.

Synergistic Effect of He for the Fabrication of Ne and Ar Gas-Charged Silicon Thin Films as Solid Targets for Spectroscopic Studies.

Sputtering of silicon in a He magnetron discharge (MS) has been reported as a bottom-up procedure to obtain He-charged silicon films (i.e., He nanobubbles encapsulated in a silicon matrix). The incorporation of heavier noble gases is demonstrated in this work with a synergistic effect, producing increased Ne and Ar incorporations when using He-Ne and He-Ar gas mixtures in the MS process. Microstructural and chemical characterizations are reported using ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). In addition to gas incorporation, He promotes the formation of larger nanobubbles. In the case of Ne, high-resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) are reported, with remarkable dependence of the Ne 1s photoemission and the Ne K-edge absorption on the nanobubble's size and composition. The gas (He, Ne and Ar)-charged thin films are proposed as "solid" targets for the characterization of spectroscopic properties of noble gases in a confined state without the need for cryogenics or high-pressure anvils devices. Also, their use as targets for nuclear reaction studies is foreseen.

Chemical characterization of Thymus zygis L. (thyme) and Elettaria cardamomum L. (cardamom) essential oils and investigation of their inhibitory potentials against cervicovaginal Escherichia coli isolates

IntroductionThe cervicovaginal microbiota plays a crucial role in women's well-being and reproductive health. This study initially focuses on identifying the chemical components of the essential oils (EOs) from Elettaria cardamomum L. (cardamom) (Ec) and Thymus zygis L. (thyme) (Tz). Subsequently, this study aims to determine the antimicrobial and biofilm inhibitory effects of these EOs against both cervicovaginal mixed cultures and the microbial strains isolated from them. MethodsThe compositions of EOs were determined by GC–MS analysis using an Agilent 7890B GC/5977A Series MSD System. Cervicovaginal samples were obtained from two women presenting complaints of a strong odor and vaginal discharge. Samples were collected from the cervix using a sterile cytobrush, ensuring no contact with the urethra, rectum, or external parts of the vagina. The cytological examination was conducted using Papanicolaou staining. Isolated microorganisms were identified through 16S Ribosomal RNA Gene Sequence Analysis and characterized using antibiogram tests. Antimicrobial tests of the EOs were performed by broth microdilution and disc diffusion methods. Biofilm formation was assessed using a crystal violet binding assay. ResultsThe major components of Ec EO were α-terpinyl acetate (41.95 %) and eucalyptol (28.58 %), whereas Tz EO contained significant amounts of o-cymene (38.76 %), carvacrol (22.66 %), and thymol (20.69 %). Escherichia coli codes OR651248 and OR651249 were isolated from CV 6 and CV 7 mixed cultures, respectively. E. coli OR651248 demonstrated a higher antibiotic resistance level than E. coli OR651249. Biofilm formation by mixed cultures was significantly higher than that by E. coli isolates (P < 0.05). The Ec EO displayed minimal to no effect against both mixed cultures, showing zero inhibition zone, 500 μL/mL minimum inhibitory concentrations (MICs), and 500 μL/mL minimum microbicidal concentrations (MMCs). However, the Tz EO exhibited antimicrobial activity against both mixed cultures and the E. coli isolates, with inhibition zones > 15 mm and MICs/MMCs < 4 μL/mL (P < 0.05). In all microbial cultures, 0.5 MIC of both EOs inhibited biofilm formation by more than 80 %. ConclusionThe Tz EO exhibits promising potential as an antimicrobial and biofilm inhibitory agent for managing cervicovaginal E. coli infections.

Multi-proxy paleoenvironmental reconstruction of Robertson Bay, East Antarctica, since the last glacial period

Antarctic fjords and coastal bays are excellent traps for sediment and represent key areas for high-resolution investigation of past environmental conditions. Robertson Bay is an understudied coastal area located at the confluence of the Ross Sea and the Southern Ocean. Recently obtained seafloor morphology data indicate the presence of a cross-shelf elongated valley, composed of three minor basins separated by sills and seabed ridges with an arcuate shape. Several cores were collected within the basins, and investigated using a multiproxy approach including sedimentological, chemical, geochemical, and micropaleontological characterization to reconstruct the paleoenvironmental evolution from the last glacial period to present. The ages of two of these cores are constrained using ramped pyrolysis oxidation radiocarbon dating. Four sedimentary facies were recognised from which we developed a sedimentary model covering the last 21,000 years (21 ka BP). Our record provide evidence for a covering ice shelf cover from 21 to 16.5 ka BP, which gradually receded between 16,5 and 11 ka BP due to the progressive intrusion of modified Circumpolar Deep Water, thereby promoting the formation of Ice Shelf Water and High Salinity Shelf Water. From 11 to 5,8 ka BP, the ice shelf continued shrinking and nutrient-rich of modified Circumpolar Deep Water penetration onto the continental shelf progressively favoured diatom blooms and a general increase in primary productivity until 5.8 ka BP. The Late Holocene is characterised by an alternation of prolonged sea ice cover with stratified water column and strong bottom current with prolonged sea-ice free season with the intrusion of modified Circumpolar Deep Water and very slow energy bottom current.

Characterization of Biodegradable Polymers for Porous Structure: Further Steps toward Sustainable Plastics.

Plastic pollution poses a significant environmental challenge, necessitating the investigation of bioplastics with reduced end-of-life impact. This study systematically characterizes four promising bioplastics-polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and polylactic acid (PLA). Through a comprehensive analysis of their chemical, thermal, and mechanical properties, we elucidate their structural intricacies, processing behaviors, and potential morphologies. Employing an environmentally friendly process utilizing supercritical carbon dioxide, we successfully produced porous materials with microcellular structures. PBAT, PBS, and PLA exhibit closed-cell morphologies, while PHBV presents open cells, reflecting their distinct overall properties. Notably, PBAT foam demonstrated an average porous area of 1030.86 μm2, PBS showed an average porous area of 673 μm2, PHBV displayed open pores with an average area of 116.6 μm2, and PLA exhibited an average porous area of 620 μm2. Despite the intricacies involved in correlating morphology with material properties, the observed variations in pore area sizes align with the findings from chemical, thermal, and mechanical characterization. This alignment enhances our understanding of the morphological characteristics of each sample. Therefore, here, we report an advancement and comprehensive research in bioplastics, offering deeper insights into their properties and potential morphologies with an easy sustainable foaming process. The alignment of the process with sustainability principles, coupled with the unique features of each polymer, positions them as environmentally conscious and versatile materials for a range of applications.