Array Detector Research Articles

Preparation of a sustainable magnetic sorbent for the extraction and preconcentration of progestogens in natural water samples

A film composed of agarose and graphene (G) and magnetic nanoparticles (G-MNPs) is proposed as a sorbent for the extraction and determination of medroxyprogesterone (MED), levonorgestrel (LEV), norethisterone (NOR) and progesterone (PRO) in natural water samples. Both the preparation of the film and the extraction procedure were optimized. The optimal extraction parameters were as follows: isopropyl alcohol as activation solvent, sample pH value of 3.0, extraction time of 30 min, 1.00 mL of acetonitrile as eluent, elution time of 5 min and sample volume of 100.00 mL. HPLC with photodiode array detector was used for the separation and determination. The method presented a linear range between 2.50 and 75.0 μg L−1 for all analytes, and the LODs were between 1.40 and 1.80 μg L−1. The method was applied to natural water samples, obtaining satisfactory recovery values (75–111 %). In conclusion, for the immobilization of the G-MNPs, agarose was used, which is a non-toxic, renewable and biodegradable material. The G-MNPs-agarose film was reused up to 70 times, without losing its extraction capacity significantly and presenting excellent sorbent properties, which allow the extraction and preconcentration of the progestogens under study.

A fast, simple and efficient surface floating organic droplet–based air–assisted liquid–liquid microextraction for simultaneous extraction of multiclass pesticides from environmental water, mineral water and soft drink samples by HPLC–DAD

A fast, simple, efficient and selective surface floating organic droplet–based air–assisted liquid–liquid microextraction method coupled with high performance liquid chromatograph–diode array detector was developed for simultaneous extraction of six multiclass pesticides. The developed method was validated for the extraction, enrichment and quantitative determination of trace level multiclass pesticides from environmental water, mineral water and soft drink samples. The effect of experimental parameters such as type and volume of extraction solvent, addition of salt, solution pH and extraction number were successfully optimized. Under the optimum conditions, the method showed good linearity for all the six multiclass pesticide residues with coefficient of determination within the range of 0.9979–0.9994. The limit of detection and quantification were in the range 0.01 to 0.07 µg L−1 and 0.03 to 0.25 µg L−1, respectively. The reproducibility and repeatability study in terms of %RSD were in the range of 0.88–5.28 and 1.35–6.08, respectively, indicating good precision of the method. The method exhibited acceptable mean relative recovery (%RR) in the range of 71.82 to 110.16 % with %RSDs (n = 3) less than 8 % for all the samples. Thus, the developed method could be utilized as selective extraction and preconcentration of multiclass pesticides from environmental water samples, mineral water and soft drink samples, as well as samples with similar matrices.

Development of a Simultaneous Normal-Phase HPLC Analysis of Lignans, Tocopherols, Phytosterols, and Squalene in Sesame Oil Samples.

The objective of this study was to develop a simultaneous analytical method for the determination of lignans, tocols, phytosterols, and squalene using high-performance liquid chromatography coupled with a diode array and fluorescence detector (HPLC-DAD-FLD). The method employed a VertisepTM UPS silica HPLC column (4.6 × 250 mm, 5 µm) with a mobile phase mixture of n-hexane/tetrahydrofuran/2-propanol. This approach enabled the simultaneous analysis of ten compounds within 22 min. The linear correlation (R2) exceeded 0.9901. The limit of detection (LOD) and limit of quantitation (LOQ) were up to 0.43 µg mL-1 for lignans and tocopherols and up to 326.23 µg mL-1 for phytosterol and squalene. The precision and accuracy of the intra-day and inter-day variation were less than 1.09 and 3.32% relative standard deviations (RSDs). Furthermore, the developed method was applied for the analysis of targeted compounds in twenty-eight sesame oil samples (1775-8965 µg g-1 total lignans, 29.7-687.9 µg g-1 total tocopherols, 2640-9500 µg g-1 phytosterol, and 245-4030 µg g-1 squalene). The HPLC method that has been developed was proven to be a reliable and effective tool for the determination of those functional compounds among sesame oil samples.

Pushing the high count rate limits of scintillation detectors for challenging neutron-capture experiments

One of the critical aspects for the accurate determination of neutron capture cross sections when combining time-of-flight and total energy detector techniques is the characterization and control of systematic uncertainties associated to the measuring devices. In this work we explore the most conspicuous effects associated to harsh count rate conditions: dead-time and pile-up effects. Both effects, when not properly treated, can lead to large systematic uncertainties and bias in the determination of neutron cross sections. In the majority of neutron capture measurements carried out at the CERN n_TOF facility, the detectors of choice are the C6D6 liquid-based either in form of large-volume cells or recently commissioned sTED detector array, consisting of much smaller-volume modules. To account for the aforementioned effects, we introduce a Monte Carlo model for these detectors mimicking harsh count rate conditions similar to those happening at the CERN n_TOF 20 m flight path vertical measuring station. The model parameters are extracted by comparison with the experimental data taken at the same facility during 2022 experimental campaign. We propose a novel methodology to consider both, dead-time and pile-up effects simultaneously for these fast detectors and check the applicability to experimental data from 197Au(n, γ), including the saturated 4.9 eV resonance which is an important component of normalization for neutron cross section measurements.

Metal-Organic Framework (MOF-199) Coated by Molecularly Imprinted Poly MMA-EGDMA for Solid Phase Extraction of Carbofuran from Fruit Samples

A selective adsorbent was synthesized based on the coating of a molecularly imprinted poly (methyl methacrylate-ethylene glycol dimethacrylate) (poly (MMA-EGDMA)) on the surface of metal-organic frameworks (MOFs) to obtain MMA-EGDMA@MOF-199 and used for the separation and preconcentration of carbofuran. Subsequently, carbofuran was determined by high-performance liquid chromatography with a diode array detector (HPLC-DAD). X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used to characterize the synthesized adsorbent. Both pH and extraction time were optimized as crucial extraction parameters. The adsorption capacity of the adsorbent was 20 mg g−1. The selectivity of the synthesized adsorbent for similar compounds was also investigated. Under the optimal conditions, the calibration curve was linear from 1.0 to 400 μg L−1. A high extraction efficiency (94%) was obtained for carbofuran with a limit of detection (LOD) of 0.4 µg L−1. The adsorbent was successfully applied to the SPE of carbofuran from fruit samples after its extraction, followed by high-performance liquid chromatography analysis.

Ultrasound-based strategies for the recovery of microalgal carotenoids: Insights from green extraction methods to UV/MS-based identification

Carotenoids, versatile natural pigments with numerous health benefits, face environmental concerns associated with conventional petrochemical-based extraction methods and limitations of their synthetic equivalents. In this context, this study aims to introduce eco-friendly approaches using ultrasound-based strategies (probe and bath) for the extraction of carotenoids from microalgae, initially focusing on Microchloropsis gaditana and subsequently evaluating the versatility of the method by applying it to other microalgae species of interest (Tisochrysis lutea, Porphyridium cruentum, and Phaeodactylum tricornutum) and defatted microalgal residues. Among the approaches evaluated, the 5-min ultrasonic probe system with ethanol showed comparable carotenoid recovery efficiency to the reference method (agitation, 24 h, acetone) (9.4 ± 2.5 and 9.6 ± 3.2 mg g−1 carotenoids per dry biomass, for the green and the reference method, respectively). Moreover, the method's sustainability was demonstrated using the AGREEprep™ software (scored 0.62 out of 1), compared to the traditional method (0.22 out of 1). The developed method yielded high carotenoid contents across species with diverse cell wall compositions (3.1 ± 0.2, 2.1 ± 0.3, and 4.1 ± 0.1 mg g−1 carotenoid per dry biomass for T. lutea, P. cruentum, and P. tricornutum, respectively). Moreover, the application of the method to defatted biomass showed potential for microalgal valorization with carotenoid recovery rates of 41 %, 60 %, 61 %, and 100 % for M.gaditana, P. tricornutum, T. lutea, and P. cruentum, compared to the original biomass, respectively. Furthermore, by using high-performance liquid chromatography with a diode array detector (HPLC-DAD) and high-resolution mass spectrometry (HRMS), we reported the carotenoid and chlorophyll profiles of the different microalgae and evaluated the impact of the eco-friendly methods. The carotenoid and chlorophyll profiles varied depending on the species, biomass, and method used. In summary, this study advances a green extraction method with improved environmental sustainability and shorter extraction time, underscoring the potential of this approach as a valuable alternative for the extraction of microalgal pigments.

Optimization of HPLC Method by Using Central Composite Design for Simultaneous Estimation of Montelukast and Ebastine Dosage Form

In this work, a novel method for the simultaneous estimate of Montelukast (MONT) and Ebastine (EBAS) in bulk drugs was developed using Central Composite Design (CCD).A novel reverse-phase high-performance liquid chromatography (RP-HPLC) approach for the simultaneous measurement of Montelukast and Ebastine in bulk and formulation is what this work aims to create and test.A novel reverse-phase high-performance liquid chromatography (RP-HPLC) approach for the simultaneous measurement of Montelukast and Ebastine in bulk and formulation is what this work aims to create and test.With isocratic elution at a flow rate of 0.8 ml min-1 and a diode array detector operating at 241 nm, the separation was accomplished using methanol and 0.02M ammonium acetate buffer (pH 5.5 adjusted with diluted acetic acid) in the ratio of 80:20 v/v. Methanol composition (percent) (A), pH (B), and flow rate (C) were three independent variables that were examined.This method showed good linearity over a range of 2.5–25 μg/ml for both drugs. MONT limit of detection (LOD) and limit of quantitation (LOQ) were 0.298 and 0.905μg/ml while LOD and LOQ for EBAS were 0.594 and 1.80For both drugs, this technique demonstrated high linearity throughout a range of 2.5–25 μg/ml. Limits of detection (LOD) and quantitation (LOQ) for MONT were 0.298 and 0.905 μg/ml and 0.594 and 1.80 μg/ml for EBAS, respectively.The statistical data analysis determined that the Methanol composition and pH were the two independent variables that were most significant, with P 0.001. The suggested technique worked well and was optimised for the CCD model-based simultaneous estimate of both drugs.

Antimicrobial and Antiplasmodial Activities of Endophytic Fungi Associated with Psidium guajava

Infections due to antimicrobial-resistant microorganisms have become widespread in recent years. Thus, searching for novel antimicrobial agents to combat such pathogens has become crucial. The current study aimed to evaluate the antimicrobial, antiplasmodial, and immunomodulatory activities of the extracts of endophytic fungi isolated from Psidium guajava. Isolation, identification, fermentation, and extraction of the secondary metabolites of the fungal endophytes were carried out following standard procedures. The extracts were subjected to High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) analysis to detect their bioactive components. The Antimicrobial activity and Minimum Inhibitory Concentration of the fungal extracts were evaluated against pure cultures of Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumonia using Agar well diffusion and Agar dilution method respectively. The acute toxicity study (LD50) was carried out using Lorke’s method. The extracts were tested in vivo in mice for antiplasmodial activity against Plasmodium berghei and in vitro against Plasmodium falciparum using Peter and Reyley's curative test method and WHO standardized micro-test system with modification respectively. The immunomodulatory activity of the extracts was evaluated by cyclophosphamide-induced myelosuppression (hematological parameters). Active extracts were further subjected to Delayed-Type Hypersensitivity Response (DTHR) and Haemagglutination Inhibition Assay using Sheep Red Blood Cells as antigens. The result showed Alternaria sp. (PGL1, PGL2, PGL3), from P. guajava. The HPLC-DAD analysis revealed the presence of bioactive compounds previously reported to have antimicrobial, antiplasmodial, and immunomodulatory properties. The fungal extracts exhibited varying degrees of antimicrobial activity. The LD50 of the fungi extracts was>5000 mg/kg in mice. The extracts at 100 and 200 mg/kg body weight in mice showed varying degrees of antiplasmodial activity. Growth of P. berghei was significantly (p<0.001) inhibited, curative effect ranges from 59.09 – 100%. Schizont maturation of P. falciparum isolates was inhibited and the highest level of inhibition was observed at 1 mg/ml (p<0.05). The fungal extracts reversed the effect of cyclophosphamide-induced reduction in total white blood cell counts and % neutrophil. This study showed that the tested plant harbors species of endophytic fungi that contain numerous secondary metabolites. The endophytic fungi showed prophylactic, immunostimulatory, and antiplasmodial activities, which can be exploited to develop antimicrobial, antiplasmodial, and immunomodulatory agents.

Multi-beam coherent Fourier scatterometry

Inspection of surface and nanostructure imperfections play an important role in high-throughput manufacturing across various industries. This paper introduces a novel, parallelised version of the metrology and inspection technique: Coherent Fourier scatterometry (CFS). The proposed strategy employs parallelisation with multiple probes, facilitated by a diffraction grating generating multiple optical beams and detection using an array of split detectors. The article details the optical setup, design considerations, and presents results, including independent detection verification, calibration curves for different beams, and a data stitching process for composite scans. The study concludes with discussions on the system’s limitations and potential avenues for future development, emphasizing the significance of enhancing scanning speed for the widespread adoption of CFS as a commercial metrology tool.

Neural networks for separation of cosmic gamma rays and hadronic cosmic rays in air shower observation with a large area surface detector array

The Tibet ASγ experiment has been observing cosmic gamma rays and cosmic rays in the energy range from teraelectron volts to several tens of petaelectron volts with a surface detector array since 1990. The derivation of cosmic gamma-ray flux is made by finding the excess distribution of the arrival direction of air showers above background cosmic rays. In 2014, the underground water Cherenkov muon detector (MD) was added to separate cosmic gamma rays from the background on the basis of the muon-less feature of the air showers of gamma-ray origin; hybrid observations using these two detectors were started at this time. In the present study, we developed methods to separate gamma-ray-induced air showers and hadronic cosmic-ray-induced ones using the measured particle number density distribution to improve the sensitivity of cosmic gamma-ray measurements using the Tibet air shower array data alone before the installation of the MD. We tested two approaches based on neural networks. The first method used feature values representing the lateral spread of the secondary particles, and the second method used the shower image data. To compare the separation performance of each method, we analyzed Monte Carlo air shower events in the vertically incident direction with mono-initial-energy gamma rays and protons. When discriminated by a single feature, the feature with the highest separation performance has an area under the curve (AUC) value of 0.701 for a gamma-ray energy of 10 TeV and 0.808 for 100 TeV. A separation method with a multilayer perceptron (MLP) based on multiple features has AUC values of 0.761 for a gamma-ray energy of 10 TeV and 0.854 for 100 TeV, which represents an improvement of approximately 5% in the AUC value compared with the single-feature case. We also found that the feature values that effectively contribute to the separation vary depending on the energy. A separation method with a convolutional neural network (CNN) using the shower image data has AUC values of 0.781 for a gamma-ray energy of 10 TeV and 0.901 for 100 TeV, which are approximately 5% higher than those of the MLP method. We applied the CNN separation method to Monte Carlo gamma-ray and cosmic-ray events from the Crab Nebula in the energy range 10–100 TeV. The AUC values range from 0.753 to 0.879, and the significance of the observed gamma-ray excess is improved by 1.3 to 1.8 times compared with the case without the separation procedure.

Enhanced Light Absorption and Elevated Viscosity of Atmospheric Brown Carbon through Evaporation of Volatile Components.

Samples of brown carbon (BrC) material were collected from smoke emissions originating from wood pyrolysis experiments, serving as a proxy for BrC representative of biomass burning emissions. The acquired samples, referred to as "pyrolysis oil (PO1)," underwent subsequent processing by thermal evaporation of their volatile compounds, resulting in a set of three additional samples with volume reduction factors of 1.33, 2, and 3, denoted as PO1.33, PO2, and PO3. The chemical compositions of these POx samples and their BrC chromophore features were analyzed using a high-performance liquid chromatography instrument coupled with a photodiode array detector and a high-resolution mass spectrometer. The investigation revealed a noteworthy twofold enhancement of BrC light absorption observed for the progression of PO1 to PO3 samples, assessed across the spectral range of 300-500 nm. Concurrently, a decrease in the absorption Ångstrom exponent (AAE) from 11 to 7 was observed, indicating a weaker spectral dependence. The relative enhancement of BrC absorption at longer wavelengths was more significant, as exemplified by the increased mass absorption coefficient (MAC) measured at 405 nm from 0.1 to 0.5 m2/g. Molecular characterization further supports this darkening trend, manifesting as a depletion of small oxygenated, less absorbing monoaromatic compounds and the retention of relatively large, less polar, more absorbing constituents. Noteworthy alterations of the PO1 to PO3 mixtures included a reduction in the saturation vapor pressure of their components and an increase in viscosity. These changes were quantified by the mean values shifting from approximately 1.8 × 103 μg/m3 to 2.3 μg/m3 and from ∼103 Pa·s to ∼106 Pa·s, respectively. These results provide quantitative insights into the extent of BrC aerosol darkening during atmospheric aging through nonreactive evaporation. This new understanding will inform the refinement of atmospheric and chemical transport models.

Improving photon number resolvability of a superconducting nanowire single-photon detector array using a level comparator circuit

Photon number resolving (PNR) capability is very important in many optical applications, including quantum information processing, fluorescence detection, and few-photon-level ranging and imaging. Superconducting nanowire single-photon detectors (SNSPDs) with a multipixel interleaved architecture give the array an excellent spatial PNR capability. However, the signal-to-noise ratio (SNR) of the PNR (SNRPNR) of the array will be degraded with increasing the element number due to the electronic noise in the readout circuit, which limits the PNR resolution as well as the maximum PNR number. In this study, a 16-element interleaved SNSPD array was fabricated, and the PNR capability of the array was investigated and analyzed. By introducing a level comparator circuit (LCC), the SNRPNR of the detector array was improved over a factor of four. In addition, we performed a statistical analysis of the photon number on this SNSPD array with LCC, showing that the LCC method effectively enhances the PNR resolution. Besides, the system timing jitter of the detector was reduced from 90 ps to 72 ps due to the improved electrical SNR.

Analysis of Lemon Verbena Polyphenol Metabolome and Its Correlation with Oxidative Stress under Glucotoxic Conditions in Adipocyte.

Lemon verbena has been shown to ameliorate obesity-related oxidative stress, but the intracellular final effectors underlying its antioxidant activity are still unknown. The purpose of this study was to correlate the antioxidant capacity of plasma metabolites of lemon verbena (verbascoside, isoverbascoside, hydroxytyrosol, caffeic acid, ferulic acid, homoprotocatechuic acid, and luteolin-7-diglucuronide) with their uptake and intracellular metabolism in hypertrophic adipocytes under glucotoxic conditions. To this end, intracellular ROS levels were measured, and the intracellular metabolites were identified and quantified by high-performance liquid chromatography with a diode array detector coupled to mass spectrometry (HPLC-DAD-MS). The results showed that the plasma metabolites of lemon verbena are absorbed by adipocytes and metabolized through phase II reactions and that the intracellular appearance of these metabolites correlates with the decrease in the level of glucotoxicity-induced oxidative stress. It is postulated that the biotransformation and accumulation of these metabolites in adipocytes contribute to the long-term antioxidant activity of the extract.

Spectral Reconstruction Improvement in a Cycloidal Coded-Aperture Mass Spectrometer.

Spatial aperture coding is a technique used to improve throughput without sacrificing resolution both in optical spectroscopy and sector mass spectrometry (MS). Previous work demonstrated that aperture coding combined with a position-sensitive array detector in a miniature cycloidal mass spectrometer was successful in providing high-throughput, high-resolution measurements. However, due to poor alignment and field nonuniformities, reconstruction artifacts were present. Recently, significant progress was made in eliminating most of the reconstruction artifacts with improved field uniformity and alignment. However, artifacts as large as 1/3 of the main peak were still observed at low mass (<17 u). Such artifacts will reduce accuracy in identification and quantification of analytes, reducing the impact of the throughput advantage gained by using a coded aperture. The artifacts were hypothesized to be a result of a mass dependent in curvature of ions in the ion source. Ions with higher mass (m/z > 17 u) and a larger curvature did not pass through all slits in the coded aperture. Therefore, when reconstructing with a system response derived from the aperture image from a higher mass m/z = 32 u ion, reconstruction artifacts appeared for m/z < 17 u. In this work, two methods were implemented to significantly reduce the presence of artifacts in reconstructed data. First, we modified the reconstruction algorithm to incorporate a mass-dependent system response function across the mass range (10-110 u). This method reduced the size of the artifacts by 82%. Second, to validate the hypothesis that the mass-dependent system response function was a result of differences in curvature of ions in the ion source, we modified the design of the ion source by shifting the coded aperture slits relative to the center of the ionization volume. This method resulted in ions of all masses passing through all slits in the coded aperture, a constant system response function across the entire mass range. Artifacts were reduced by 94%.

Application of continuous magnetic solid phase extraction in the extraction of tetracycline antibiotics from honey samples

This study aimed to develop a continuous magnetic solid phase extraction method in a narrow bore tube for the extraction of tetracycline antibiotics from honey samples before their determination with high performance liquid chromatography–diode array detector. In this work, a magnetic covalent organic framework is used as the sorbent. The extraction method is performed in a narrow bore tube by adding 25 mg of a magnetic sorbent prepared from melamine, barbituric acid, and Fe3O4 into the diluted honey sample solution. By using a magnet, the sorbent is moved up and down through the narrow bore tube for five times to improve extraction efficiency. After adsorption the analytes, they are eluted from the sorbent surface using 2,2–dimethoxypropane under vortexing. Then, by using a magnet, the eluent containing the extracted analytes are taken and evaporated with continuous flow of nitrogen. Finally, the residue containing the enriched analytes is reconstituted in microliter–level of mobile phase and injected into chromatographic system for quantitative analysis. Based on the outcomes, the method demonstrated good linearity (0.37–1000 ng g−1), high enrichment factors (175–203), good extraction recoveries (70–81 %), low LODs (0.11–0.18 ng g−1) and LOQs (0.37–0.60 ng g−1). The proposed method is effectively applied for quantification of tetracyclines in twenty–four honey samples. Considering the results, none of the honey samples was contaminated with the studied antibiotics. Regarding to the above–mentioned analytical advantages of the proposed method, its simplicity and rapidity, and green synthesis of the magnetic sorbent particles, the suggested method can be used as a routine method for the extraction of tetracyclines from honey samples.

Determination of antibiotics of the tetracycline group in water by high-performance liquid chromatography on a diode matrix detector with preliminary concentration by solid-phase extraction

Introduction. Antibiotic contamination of the environment is a serious environmental threat that poses a hazard to human health. To monitor the content of tetracycline antibiotics in environmental objects and control technological processes aimed at their disposal, accessible analytical methods are needed. &#x0D; Purpose of the study. Development of a method for determining antibiotics of the tetracycline group in water using a diode array detector with preliminary solid-phase concentration.&#x0D; Material and methods. The objects of the study were model solutions of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline in deionized, tap, natural, and treated wastewater. For solid-phase extraction, Diapak P and Diapak PG cartridges were used. SPE was performed using a VacMaster-10 manifold (Biotage). Chromatographic separation was carried out on Diasphere C10CN and Kromasil Eternity 250 × 4.6 mm 5 µm columns on an Agilent 1100 liquid chromatograph (Agilent Technology).&#x0D; Results. Optimal conditions for the chromatographic separation of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline were selected: isocratic mode, wavelength of 350 nm, mobile phase – acetonitrile: aqueous solution of phosphoric acid (pH = 3.0). The analysis time on Diasphere C10CN and Kromasil Eternity columns was 12 and 14 minutes, respectively. The reliability of the linear approximation in both cases was more than 0.99, however, the slopes on the Kromasil Eternity column were 1.35 –1.65 times higher than on Diasphere C10CN. The degree of extraction of tetracyclines from deionized water on Diapak P and Diapak PG cartridges was 90–95%, from tap water 61–89%, from purified waste water: 51–87%.&#x0D; Limitations. The method is not suitable for water bodies with tetracycline contents less than 2 µg/dm3.&#x0D; Conclusion. An HPLC method has been developed for the determination of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline in water with preliminary SPE concentration on Diapak P and Diapak PG cartridges. The lower limit of determination for the sorption of target compounds from 0,1 dm3 of sample was 2 μg/dm3.

Evaluation of some sulfonamide antibiotics residues in chicken meat samples using in-syringe counter current homogenous liquid–liquid extraction and magnetic deep eutectic solvent-based dispersive liquid–liquid microextraction and HPLC–DAD

A sample pretreatment method based on the combination of counter current salting-out homogenous liquid–liquid extraction and magnetic deep eutectic solvent-based dispersive liquid–liquid microextraction was developed and employed for the extraction of some sulfonamide antibiotics from chicken meat samples. For this purpose, first, a homogenous solution of acetonitrile and deionized water was passed through a syringe barrel filled sodium chloride and chicken meat sample. By doing so, the fine droplets of acetonitrile were produced and collected on the surface of solution. In the following, this phase containing the extracted analytes was taken and injected into deionized water after mixing with [Choline: 4-chlorophenol]+[FeCl4]- magnetic deep eutectic solvent. Then, the magnetic deep eutectic solvent droplets were separated in the presence of an external magnetic field and injected into high performance liquid chromatography-diode array detector for quantitative analysis. Based on the validation results, low limits of detection (0.15–0.24 ng g−1) and quantification (0.51–0.80 ng g−1), high extraction recovery (67–78 %), and good precision (relative standard deviations ≤ 5.7 %) were obtainable by using the offered method. Finally, the suggested method was employed for the quantification of the studied sulfonamide antibiotics in various chicken meat samples.

Green Approach for Synthesis of Silver Nanoparticles with Antimicrobial and Antioxidant Properties from Grapevine Waste Extracts.

The present work aims to study the possibilities of developing silver nanoparticles using natural extracts of grape pomace wastes originating from the native variety of Fetească Neagră 6 Șt. This study focused on investigating the influence of grape pomace extract obtained by two different extraction methods (classical temperature extraction and microwave-assisted extraction) in the phytosynthesis process of metal nanoparticles. The total phenolic content of the extracts was assessed using the spectrophotometric method with the Folin-Ciocâlteu reagent, while the identification and quantification of specific components were conducted through high-performance liquid chromatography with a diode array detector (HPLC-DAD). The obtained nanoparticles were characterized by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), along with assessing their antioxidant and antimicrobial properties against Gram-positive bacteria. The data collected from the experiments indicated that the nanoparticles were formed in a relatively short period of time (96 h) and, for the experimental variant involving the use of a 1:1 ratio (v/v, grape pomace extract: silver nitrate) for the nanoparticle phytosynthesis, the smallest crystallite sizes (from X-ray diffraction-4.58 nm and 5.14 nm) as well as spherical or semispherical nanoparticles with the lowest average diameters were obtained (19.99-23 nm, from TEM analysis). The phytosynthesis process was shown to enhance the antioxidant properties (determined using the DPPH assay) and the antimicrobial potential (tested against Gram-positive strains) of the nanoparticles, as evidenced by comparing their properties with those of the parent extracts; at the same time, the nanoparticles exhibited a selectivity in action, being active against the Staphylococcus aureus strain while presenting no antimicrobial potential against the Enterococcus faecalis strain.

High Elevation Radiation Array (HERA) detectors for airborne thunderstorm investigations

A high-energy atmospheric physics phenomenon, referred to as a terrestrial gamma ray flash (TGF), is associated with lightning and produces large bursts of energetic photon radiation. TGFs will be investigated using a suite of gamma-ray instruments designed and constructed to fly on ten United States Air Force (USAF) WC-130J Hurricane Hunter aircraft as part of an aircrew ionization study led by the Air Force Institute of Technology (AFIT) and the United States Air Force School of Aerospace Medicine (USAFSAM), in cooperation with the 53rd Weather Reconnaissance Squadron (WRS). Each instrument consists of one NaI and one plastic detector, a GPS timing device, and an instrument computer that performs data acquisition. High Elevation Radiation Array (HERA) detectors will be employed to maximize the chances of observing TGFs near their source and to gain a better understanding of their origin, mechanism, ubiquity, and to assess potential hazards posed to military and commercial aircrew and passengers. The HERA program, deployed on 10 separate Air Force aircraft over a multi-year campaign, will result in thousands of observational flight hours and be the largest concerted effort to date to observe TGFs in situ through aircraft observations. In this paper, we give an overview of the scientific goals of this campaign and how the HERA instruments have been designed to meet those goals. We include a detailed description of the HERA instrument, along with mass model and signal processing simulations.

Thermalization of Mesh Reinforced Ultra-Thin Al-Coated Plastic Films: A Parametric Study Applied to the Athena X-IFU Instrument.

The X-ray Integral Field Unit (X-IFU) is one of the two focal plane detectors of Athena, a large-class high energy astrophysics space mission approved by ESA in the Cosmic Vision 2015-2025 Science Program. The X-IFU consists of a large array of transition edge sensor micro-calorimeters that operate at ~100 mK inside a sophisticated cryostat. To prevent molecular contamination and to minimize photon shot noise on the sensitive X-IFU cryogenic detector array, a set of thermal filters (THFs) operating at different temperatures are needed. Since contamination already occurs below 300 K, the outer and more exposed THF must be kept at a higher temperature. To meet the low energy effective area requirements, the THFs are to be made of a thin polyimide film (45 nm) coated in aluminum (30 nm) and supported by a metallic mesh. Due to the small thickness and the low thermal conductance of the material, the membranes are prone to developing a radial temperature gradient due to radiative coupling with the environment. Considering the fragility of the membrane and the high reflectivity in IR energy domain, temperature measurements are difficult. In this work, a parametric numerical study is performed to retrieve the radial temperature profile of the larger and outer THF of the Athena X-IFU using a Finite Element Model approach. The effects on the radial temperature profile of different design parameters and boundary conditions are considered: (i) the mesh design and material, (ii) the plating material, (iii) the addition of a thick Y-cross applied over the mesh, (iv) an active heating heat flux injected on the center and (v) a Joule heating of the mesh. The outcomes of this study have guided the choice of the baseline strategy for the heating of the Athena X-IFU THFs, fulfilling the stringent thermal specifications of the instrument.