Fluorescence Spectrometry Method Research Articles

Rapid Quantification of Oxytetracycline Based on Fluorescence Enhancement Influenced by pH.

Accurate quantification of antibiotics in environmental samples is typically challenging due to the low antibiotic concentrations and the complexity of environmental matrices. This paper presents a fluorescence spectrometry method for determining oxytetracycline under alkaline conditions. The ionic distribution of the oxytetracycline solution was analyzed based on its dissociation constant. The dimethylamino group plays a crucial role in this method, as it promotes intramolecular charge transfer in the electronic excited state through its electron-donating capability with a lone electron pair. The presented method is straightforward, cost-effective, and holds potential for analyzing oxytetracycline in water sample after further investigation.

Estimated daily intake and health risk assessment of total and organic selenium in crops across areas with different selenium levels

BackgroundThe health risk of Se has gained significant attention. Previous studies mainly focused on the health risk of total Se in high-Se area. Less attention has been paid to the health risk of organic selenium in areas with varying selenium levels. MethodsA total number of 109 crop samples (edible parts) were collected in Langao County, Shannxi Province, China from 2018 to 2020, including 42 corn, 18 rice, 9 sweet potato, 25 potato, 12 radish, and 3 eggplant samples. The hydride generation atomic fluorescence spectrometry (HG-AFS) method was used to determine the total and organic Se contents. Result and conclusion(1) Corn (2.82 mg/kg), rice (0.44 mg/kg), potato (6.56 mg/kg), and eggplant (0.77 mg/kg) in high-Se area, as well as sweet potato (1.07 mg/kg) and radish (4.28 mg/kg) in medium-Se area, exhibited the highest total Se content among all crops in this county, and 5–328 times higher than the values of Se-enriched standard (2) The average daily intake of total/organic Se of residents in high-Se area reached 676/449 μg/day, which was 1–4 times higher than levels observed in medium-Se area (419/257 μg/day) and low-Se area (196/128 μg/day). The organic Se daily intakes from dietary combinations of rice + radish and rice + eggplant in high-Se area lower than 400 μg/day, which could be safely consumed. The organic Se daily intakes from dietary combinations of sweet potato + radish and sweet + eggplant in medium-Se area higher than 400 μg/day, which could not be safely consumed. The total / organic Se daily intakes of all dietary combinations in low-Se area lower than 400 μg/day, which could be safely consumed. (3) The health risk associated with crops might be overestimated due to the higher non-carcinogenic risk attributed to total Se compared to organic Se. The present study demonstrated that daily intake and health risk of total and organic Se in crops across areas with different Se levels varied significantly.

Autofluorescence spectral analysis for detecting urinary stone composition in emulated intraoperative ambient

The prevalence and disease burden of urolithiasis has increased substantially worldwide in the last decade, and intraluminal holmium laser lithotripsy has become the primary treatment method. However, inappropriate laser energy settings increase the risk of perioperative complications, largely due to the lack of intraoperative information on the stone composition, which determines the stone melting point. To address this issue, we developed a fiber-based fluorescence spectrometry method that detects and classifies the autofluorescence spectral fingerprints of urinary stones into three categories: calcium oxalate, uric acid, and struvite. By applying the support vector machine (SVM), the prediction accuracy achieved 90.28 % and 96.70% for classifying calcium stones versus non-calcium stones and uric acid versus struvite, respectively. High accuracy and specificity were achieved for a wide range of working distances and angles between the fiber tip and stone surface in an emulated intraoperative ambient. Our work establishes the methodological basis for engineering a clinical device that achieves real-time, in situ classification of urinary stones for optimizing the laser ablation parameters and reducing perioperative complications in lithotripsy.

MINERAL ELEMENTS OF RUBIA TINCTORUM L PLANT ROOT AND USE IN MEDICINE

In this article, the biological properties of the root of Rubia tinctorum plant and the amount of mineral elements in its chemical composition are determined using the X-ray fluorescence spectrometry method using the Spectro Xepos 111 (SSliA) device, and the information about the use of the root of the Rubia tinctorum plant in medicine is highlighted.

Applications of Energy Dispersive X‐Ray Fluorescence Spectrometry and Direct Current Arc Atomic Emission Spectroscopy Methods for Grouping Study of Automobile Windshield Glasses for Glass Forensics

AbstractA comprehensive evaluation was carried out for elemental characterization of automobile glasses having potential forensic application by Energy Dispersive X‐ray Fluorescence (ED‐XRF) spectrometry and Direct Current Atomic Emission Spectroscopy (DC Arc AES). The methods were optimized and validated using geological certified reference materials and glass standard reference material. Total seventeen elements including five major elements (Si, Na, Ca, Mg and Fe) and twelve minor and trace elements (Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Rb, Mo, Zr and Sr) were found to be present. Though DC Arc AES performed better for minor and trace level determination, however, the precision was evaluated as 15–20 % RSD. On the contrary, ED‐XRF performed better for major elements with 5–10 % RSD. The detection limits for the analytes prone to form refractory oxides on heating were found to be poorer in DC Arc AES compared to ED‐XRF. Statistical analyses were also performed to evaluate the reliability of the data obtained by the optimized methods. As a part of forensic applications, the elemental concentrations of minor and trace elements were utilized for the grouping study of the glass samples by cluster analysis using average linkage method.

Determination of Se and Te by hydride generation-inductively coupled plasma mass spectrometry after mixed-acid digestion of tungsten ores

Se and Te in tungsten ores are important parameters for exploring the metallogenetic process of tungsten ores; however, due to their high refractory, low abundance, extreme volatilization, as well as the complex matrix interference during analysis, it is a challenge to accurately determining their concentrations in tungsten ores. This study presents a method of combining hydride generation device with inductively coupled plasma mass spectrometry (HG-ICP-MS) to determine the contents of Se and Te in tungsten ores. As a pre-processing step, tungsten ores were dissolved in the mixture of HF + HNO3 + HClO4 and microwaved for digestion. The analytical results show that the main matrix components (K, Na, Ca, Mg, Fe, Mn and Pb) in tungsten ores have no interference, and the interference of W, Cu, Zn and Bi can be eliminate by adding an appropriate amount of Fe3+. The method was used to test 6 samples with different tungsten concentrations. Compared with the results of hydride generation atomic fluorescence spectrometry (HG-AFS) method, the mean values of HG-ICP-MS method showed a good consistency and the relative mean deviations of Se and Te contents were in the range of −5.2%­ to 6.2% and − 3.8%­ to 3.4%, respectively. The values of Se, Te and Te/Se ratio determined from various geological samples (30 soil and sediment samples, 30 granite samples, 25 poly-metallic sulfide ore samples and 29 tungsten ore samples) highlight their potential prospecting in the metallogenetic process of tungsten ores.

Heavy Metals Contamination and Water Quality Parameter Conditions in Jatiluhur Reservoir, West Java, Indonesia

Waste pollution into the Citarum River (main water source of Jatiluhur Reservoir) was dominated by the manufacturing industry sector (textile, chemical, metal, pharmaceutical). Industrial was the most common contributor to heavy metal waste. Heavy metal contamination into waters will cause any problems, one of which was the emergence of various diseases both short and long term. Based on the issues, the study of heavy metal contamination and also water quality parameter conditions in the Jatiluhur Reservoir was necessary. The heavy metals (Cu, Zn, Hg, Pb, Cd) contents were determined using the X-Ray Fluorescence (XRF) Spectrometry method (for sediment) and Atomic Absorption Spectrometry (AAS) method (for water). The other water quality parameters were analyzed using the methods from the Indonesian National Standard (SNI). Furthermore, the data were compared to the Canadian Sediment Quality Guidelines (for heavy metal in sediment) and water quality standards from Government Regulation of the Republic of Indonesia Number 82 of 2001 (Class 3) (for water quality parameters). Concerning the discussion, Jatiluhur Reservoir was divided into three zones i.e. the inlet area, main inundation area, and outlet area. Conditions in the sedimentary layer, mercury (Hg) have accumulated throughout the Jatiluhur Reservoir area with conditions exceeding the maximum limit, while Cu metal tends to accumulate in the inlet area with conditions exceeding the minimum limit. For other heavy metals, exceed the minimum limit at some locations, but more results were below that. Although all heavy metals have not been detected in water, this was a warning that the presence of heavy metals in sediments can potentially dissolve into the water, the most extreme thing that can happen was upwelling. If this happens, the heavy metals can be contained excessively in water, harmful to and possibly consumed by aquatic biota and human. Considering these conditions, the biota that was most likely to be exposed was benthic organisms. In general, the water quality parameters in Jatiluhur Reservoir meet the quality standards. Only ammonia that does not meet the quality standards for sensitive fish life, regarding the massively of aquaculture activity in this reservoir.

Bioinspired honeycomb-like 3D architectures self-assembled from chitosan as dual-functional membrane for effective adsorption and detection of copper ion

Metal ions released through industrial and human activities are difficult to degrade in the environment, and copper (II) ingestion and accumulation in the body would cause harm to human health and even disease. The environmentally friendly materials for simultaneous detection and removal of toxic ions are urgently required to be developed. Herein, carbon dots (CDs) with excellent optical properties as crosslinking agent introduced into chitosan-based membranes with freeze casting technique. The as-synthesized fluorescent membranes (CS-CDs) could generate fluorescent response to copper (II) with adsorption capacity (12.48–49.97 mg/g). Based on the stable fluorescence signal of CS-CDs and fluorescence quenching with copper (II), a simple fluorescence spectrometry method for detection of copper (II) was established. The fluorescence intensity of CS-CD-4 decreased linearly with copper (II) concentrations ranging from 0 to 350 μmol/L. Moreover, the 3D regular honeycomb-like porous structure of CS-CDs facilitated the mass transfer and provided more effective sorption sites. The adsorption isotherm and kinetics were more suitable for the Langmuir model (R = 0.9927) and pseudo-second-order model (R = 0.9989), which indicated the adsorption were monolayer adsorption and chemisorption, respectively. As a result, the CS-CDs with dual-functionalities of detecting and adsorbing copper (II) were successfully fabricated, demonstrating the potential application prospect in environmental protection.

The Kaolinite Crystallinity and Influence Factors of Coal-Measure Kaolinite Rock from Datong Coalfield, China

In order to ascertain the kaolinite crystallinity of Carboniferous Permian coal-measure kaolinite rocks, seven groups of fresh samples were collected from below the ground in the Xiaoyu mine, Datong coalfield. Microscopy, X-ray diffraction (XRD), differential thermal analysis (DTA), infrared (IR) spectroscopy and X-ray fluorescence (XRF) spectrometry methods were applied to the samples. The petrographic analysis results show that the kaolinite rocks are characterized as compact, phaneritic, clastic, sand-bearing, sandy and silty types; the kaolinite content in the Shanxi formation and upper Taiyuan formations was more than 95%, while it was 60–90% in the middle and lower Taiyuan formations. Based on the Hinckley index and the features of XRD, DTA and IR of kaolinites, crystallinity was classified as having three grades: ordered, slightly disordered and disordered. The kaolinites’ SiO2/Al2O3 molar ratio was about 1.9–5.7, with a chemical index of alteration (CIA) of about 95.4–99.5. This research suggests that the kaolinite crystallinity correlates positively to its clay mineral content, purity and particle size, which are also related to the SiO2/Al2O3 molar ratio and CIA. The original sedimentary environment and weathering have a direct influence on kaolinite crystallinity, and the existence of organic matter is conducive to the stable existence of kaolinite. The study results have significance for the extraction and utilization of coal-measure kaolinite and the development of kaolinite crystallography and mineralogy.

The study of m-pentadecylphenol on the inhibition of mild steel corrosion in 1 M HCl solution

The acidic fluids used in the acidification of oil wells provoke corrosion of metallic materials unenviably. As a consequence, corrosion inhibitors are needed to mitigate or retard the corrosion process. Herein, we report m-pentadecylphenol as an eco-friendly corrosion inhibitor in acidic media developed from cashew nut shell liquid (CNSL), which is a low-cost and sustainable source. The inhibitor was evaluated as corrosion inhibitor for mild in 1 M HCl corrosive solution by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), weight loss, Fourier transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM), and energy-dispersive X-ray fluorescence (EDX-RF) spectrometry methods. The results showed that the inhibition efficiency of m-pentadecylphenol was at least 95% at an optimal concentration (300 ppm). The inhibition efficiency was found to increase as the inhibitor concentration increments from 100 to 300 ppm. Further studies revealed the inhibition performance of m-pentadecylphenol to be marginally reliant on temperature as the temperature rises from 303 to 333 K. At 333 K, the inhibition performance of the inhibitor was still promising (about 85%) when the concentration was 300 ppm. The adsorption studies revealed the spontaneous aptitude of m-pentadecylphenol to inhibit corrosion by forming a non-conductive inhibitive layer on the mild steel surface mainly through the chemisorption mechanism. The chemisorption adsorption was satisfactorily described by the Langmuir adsorption isotherm model. Besides, the potentiodynamic polarization measurements revealed m-pentadecylphenol to act as an anodic inhibitor. The overall findings revealed that m-pentadecylphenol to be an effective corrosion inhibitor in harsh corrosive vicinities with the added advantages of being eco-friendly and relatively cheaper. Thus, it can replace the use of non-green and expensive corrosion inhibitors in the industry.

A simple and rapid head space-single drop microextraction-‘spectro-pipette’ (HS-SDME-SP) method for the on-site measurement of arsenic species in natural waters

Arsenic (As) is a ubiquitous element in the environment while its toxicity and chemical properties are highly associated with its chemical form. High quality As speciation data in environmental matrices are thus desirable for understanding its biogeochemistry. Here we present a simple and novel head space-single drop microextraction-spectro-pipette (HS-SDME-SP) method for the on-site measurement of As species in natural waters. Arsine was generated and separated from the sample matrix by borohydride-based hydride generation, which was further extracted into a stable, hanging 5 μL microdroplet on the tip of a spectro-pipette. With the spectro-pipette, the microvolume of extractant is easily handled while gas–liquid absorption, redox and chromogenic reactions and in situ absorbance measurement can be carried out in a single step. The speciation analysis of As(III) and As(V) was achieved by utilizing their different pH requirement for reduction and arsine generation in the hydride generation process. Although the proposed method is a simple sensor based assay, it is sensitive, robust and reliable; the limit of detection (3 × S/N) was 0.1 nM, RSDs for 25 nM As(III) were < 2.0% (n = 10) and results were comparable with the commonly used hydride generation atomic fluorescence spectrometry (HG-AFS) method and in good agreement with two certified reference materials (surface freshwater and seawater). The proposed method is easy to operate, the device is light and portable (1.1 kg) and is practical for the measurement of trace inorganic As species in the field.

Resampling with in situ field portable X-ray fluorescence spectrometry (FPXRF) to reduce the uncertainty in delineating the remediation area of soil heavy metals.

There must be some uncertainty in the remediation areas delineated based on limited sample points, and resampling in the high-uncertainty areas is particularly necessary. In situ field portable X-ray fluorescence spectrometry (FPXRF), a rapid and cheap analysis method for soil heavy metals, is strongly affected by many spatially non-stationary soil factors. This study first delineated the high-uncertainty area (threshold-exceeding probabilities (PTE) between 30% and 70%) of soil Pb based on the 1000 realizations produced by sequential Gaussian simulation (SGS) with 93 ICP-MS Pb concentrations measured in a peri-urban agriculture area, China. Next, in situ FPXRF was used to increase sample density in this high-uncertainty area. Then, robust geographically weighted regression (RGWR) was used to correct the in situ FPXRF Pb, and the correction accuracies of RGWR, basic GWR, and traditionally-used ordinary least squares regression (OLSR) were compared. Finally, to explore the best way to combine these corrected in situ FPXRF concentrations in delineating the remediation area, we compared the following spatial simulation methods: basic SGS, sequential Gaussian co-simulation (CoSGS) with the RGWR-corrected in situ FPXRF Pb as auxiliary soft data (CoSGS-CorFPXRF), and SGS with the RGWR-corrected in situ FPXRF Pb as part of hard data (SGS-CorFPXRF). Results showed that (i) RGWR produced higher correction accuracy (RI=71.5%) than GWR (RI=59.68%) and OLSR (RI=25.58%) for the in situ FPXRF Pb; (ii) SGS-CorFPXRF produced less uncertainty (G=0.97) than CoSGS-CorFPXRF (G=0.95) and SGS (G=0.91) in the spatial simulation; (iii) High-uncertainty area (30%<PTE<70%) was reduced from 36.55% to 8.7% of the whole study area. It is concluded that the recommended methods are cost-effective to reduce the uncertainty in delineating the remediation areas of soil heavy metals.

Features of sample preparation techniques in the total-reflection X-ray fluorescence analysis of tea leaves

Tea is a popular drink around the world and contains essential minerals and trace elements for human health. In this study, the analytical capabilities of the total-reflection X-ray fluorescence method (TXRF) were considered for the analysis of tea. Different sample preparation techniques, e.g. suspension, open vessel acid digestion, and microwave acid digestion were examined. The influence of particle size was investigated in the analysis of the suspension of tea samples. Mass-absorption coefficients for the tea matrix and the critical surface density of the specimen were calculated. The data obtained explain the presence of absorption effects in the determination of P, S, Cl, and K in suspensions. The digestion procedure is chosen as an optimal sample preparation technique for the TXRF analysis of tea. Nineteen real tea samples were analyzed using TXRF. The advantages of TXRF have been presented through the comparison of results with the wavelength-dispersive X-ray fluorescence spectrometry method.

The Determination of Thiourea Dioxide Residue in Pasta Products by LVFX-AuNPs Fluorescence Resonance Energy Transfer Spectrometry

Fluorescence resonance energy transfer occurs between levofloxacin (LVFX) and gold nanoparticles (AuNPs), which leads to fluorescence quenching of levofloxacin. Due to the strong Au-S bond formed between thiourea dioxide and gold nanoparticles, levofloxacin is released from the surface of gold nanoparticles and fluorescence of the system is recovered. Based on this, a fluorescence spectrometry method for determination of thiourea dioxide was established. This method was used to determine the content of thiourea dioxide in pasta products with RSD less than 3.5% and recovery rate of 93.3~103.3%.

Unified method for the determination of chemical composition in different types of materials using Wavelength Dispersive X-ray Fluorescence Spectrometry

Abstract The aim of the article is to show that determination of the main chemical composition with Wavelength Dispersive X-ray Fluorescence Spectrometry method does not require the use of separate analytical applications and procedures for the tests of materials of different origin. This is however conditioned upon calcination of the tested initial sample at the temperature of 815 °C to remove organic matter and its preparation for X-ray measurements by fusing into a borate bead. Within the framework of the conducted research a special analytical application measuring 10 oxides: SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O, SO3, TiO2 and P2O5 was developed. Standards and certified reference materials (CRMs) were applied for calibration. Synthetic standards with the use of oxides and salts of purity of 99.99% were also prepared to complete the measuring points on the calibration curves The curves determined based on the measuring points have high correlation coefficients and accuracy. The α empirical correction coefficients were applied to correct matrix effects. The range of the method was confirmed based on the measurements of 13 synthetic standards. The average values of the standard deviations in the lower range of the calibration curves were between 0.0008% for K2O and 0.0056% for Na2O and 0.0054% for MgO. The average values of the relative standard deviation were in the range between 1.81% for K2O and 13.92% for MgO and 11.21% for Na2O, respectively. In the upper range of the calibration curves, the average values of standard deviation were between 0.079% for TiO2 and 0.962% for P2O5, and the relative standard deviation was between 0.05% for SiO2 and 2.39% for P2O5. The accuracy of the developed WDXRF method was assessed based on the measurement of 10 certified reference materials representing all the tested materials (cement, coal ash, slag, fire clay, sediment and soil). Out of 98 conducted measurements (two CRMs did not contain the declared content of P2O5 and SO3 respectively), in 68 measurements, relative errors were below 5%, and, in next 27 measurements, they were between 5% and 10%. The errors were comparable for all the tested materials which confirms that in WDXRF analyses of borax beads the type, kind and origin of a sample do not affect accuracy of the obtained measurements.

Development of Visible/Near-Infrared Hyperspectral Imaging for the Prediction of Total Arsenic Concentration in Soil

Soil total arsenic (TAs) contamination caused by human activities—such as mining, smelting, and agriculture—is a problem of global concern. Visible/near-infrared (VNIR), X-ray fluorescence spectroscopy (XRF), and laser-induced breakdown spectroscopy (LIBS) do not need too much sample preparation and utilization of chemicals to evaluate total arsenic (TAs) concentration in soil. VNIR with hyperspectral imaging has the potential to predict TAs concentration in soil. In this study, 59 soil samples were collected from the Daye City mining area of China, and hyperspectral imaging of the soil samples was undertaken using a visible/near-infrared hyperspectral imaging system (wavelength range 470–900 nm). Spectral preprocessing included standard normal variate (SNV) transformation, multivariate scatter correction (MSC), first derivative (FD) preprocessing, and second derivative (SD) preprocessing. Characteristic bands were then identified based on Spearman’s rank correlation coefficients. Four regression models were used for the modeling prediction: partial least squares regression (PLSR) (R2 = 0.71, RMSE = 0.48), support vector machine regression (SVMR) (R2 = 0.78, RMSE = 0.42), random forest (RF) (R2 = 0.78, RMSE = 0.42), and extremely randomized trees regression (ETR) (R2 = 0.81, RMSE = 0.38). The prediction results were compared with the results of atomic fluorescence spectrometry methods. In the prediction results of the models, the accuracy of ETR using FD preprocessing was the highest. The results confirmed that hyperspectral imaging combined with Spearman’s rank correlation with machine learning models can be used to estimate soil TAs content.

Comparison of portable X-ray fluorescence spectrometry and laboratory-based methods to assess the soil elemental composition: Applications for wetland soils

Abstract The portable X-ray fluorescence spectrometry (pXRF) can be considered one of the most novelty for soil characterization. In tropical regions (e.g., Brazil), some studies have showed a consistent correlation between pXRF and laboratory-based methods. However, there is no any work dedicated exclusively for hydromorphic soils (gley or organic-rich soils). This study aims to assess the total elemental composition reported by portable X-ray fluorescence (pXRF) spectrometry and to compare it to laboratory-based wet digestion method and wavelength dispersive X-ray (WDXRF) spectrometry. A collection of 144 hydromorphic soil samples from six wetlands located in the Cerrado biome (Savannah), Brazil, was used for this investigation. Soil samples were disaggregated and passed through a 150- μ m nylon mesh and subjected to wet digestion (US EPA 3051a) followed by elemental determination via atomic absorption spectrometry (AAS). Subsamples of each ground soil were also directly analyzed via both pXRF and WDXRF. Linear regressions were performed to establish the relationship between methods. Several elements (Pb, Cu, Zn, Cr, Fe, Ti, Sr, and Y) determined via pXRF were successfully correlated to other methods (USEPA 3051a and WDXRF). Specially for Pb, a very strong correlation (R > 0.90) was observed between pXRF, WDXRF and US EPA 3051a methods. The pXRF revealed also to be a useful tool for characterization of hydromorphic soils and future studies can be conducted directly in the field to assess the elemental composition of Cerrado wetland soils.

Paper-based sensor for visual detection of Ag+ based on a “turn-off-on” fluorescent design

A fluorescence paper-based sensor method by simply using thiomalic acid modified CdTe (TMA-capped CdTe) was proposed for visual detection of silver ions (Ag+). Red-emission TMA-capped CdTe with a large amount of carboxyl groups on the surface could be combined with Ag+ by electrostatic interaction, thus leading to the fluorescence quenching. It was found that the adding of amino acids contributed to fluorescence recovery by the leaving of Ag+ on the surface of TMA-capped CdTe. Moreover, the more amino group, benzene and thiol group equipped in the structure of amino acid, the stronger fluorescence restoring of CdTe could be achieved. This fluorescence spectrometry method for Ag+ showed low detection of limit with the value of 13.16 nmol/L, with no response to other heavy metals, which demonstrating its high sensitivity and high selectivity for Ag+. More importantly, this paper-based sensor method combined with chemometrics could accurately identify and quantify different concentrations of Ag+ in different complex matrices. This fast, economical, accurate and effective approach exhibited a new idea for the on-site detection of Ag+, and was expected to be extended to the on-site detection of Ag+ in biological and environmental fields.

A novel method for quantifying the permeability of isolated small venules

BackgroundThe wall of venules is the primary site for the regulation of the transfer of water, ions and larges molecules in order to maintain tissue homeostasis. The impairment of venular permeability can cause tissue edema, followed by organ dysfunction. To date, although some methods are available to visualize the permeability of vessels, the quantification of the results remains elusive. Thus the aim of the present study was to develop a novel method to quantify the permeability of small isolated venules.MethodsMouse mesenteric venules (160–200 μm diameter at 8.0 mmHg of perfusion pressure) were isolated, cannulated in a vessel chamber and perfused with MOPS‐PSS (pH=7.4 at 37°C). The perfusion chamber contained two glass cannulas (inflow and outflow). A PE tubing of 15 mm in length with a rectangular window (2 × 7 mm) carved in the center is pre‐inserted onto the inflow pipette. After a venule was cannulated, the PE tubing was pushed forward (directed from inflow to the outflow pipette) to create a small sealed pool between the two cannulas (see the illustration). The chamber solution was then aspirated, the micro‐pool was washed and filled with 30 μl fresh MOPS‐PSS through the opened window. The inflow and outflow pressures were set at 8 cmH2O to maintain a constant intravascular pressure. The perfusion apparatus was then placed into a 37°C humidified incubator to equilibrate for 30 minutes. After equilibration, a one‐cmH2O pressure gradient was established by an increasing the inflow pressure and a decreasing the outflow pressure equally to create a constant intraluminal flow composed of MOPS‐PSS containing 5×10−4 M Evans blue dye (EBD). Thus, changes in permeability of venules could be assessed by determining the EBD in the pool solution using fluorescence (620/680 nm) spectrometry method. The final level of EBD in samples was determined using an EBD standard curve (0.08–20 μg/ml) and normalized to the internal surface area of venules.ResultsHistamine (2×10−5, 2×10−4 and 2×10−3 M) elicited a dose‐dependent increase in EBD permeability from 7.63 ± 0.79 to 21.70 ± 2.28 ng/mm2/min. The histamine‐induced release of EBD was continuous and reached a peak within 15 min, responses that were significantly reduced by triprolidine hydrochloride an H1 receptor inhibitor to 14.71± 2.07 ng/mm2/min. In addition, we have found that 5% erythrocytes lysate (ECL) and 2 μg/ml lipopolysaccharide (LPS) significantly enhanced EBD permeability.ConclusionsUsing this novel micro‐chamber technique, we were able to quantify histamine, ECL, and LPS‐induced increases in permeability of isolated venules, thus this method offers a valuable tool for pharmacokinetic research of permeability at the scale of microcirculation.Support or Funding InformationSupportNIH HL070653 (An Huang) and HL129797 (Dong Sun),Scientific Excellence Program 2019, at the University of Physical Education, Innovation and Technology Ministry, Hungary TUDFO/51757/2019‐ITM (Akos Koller).

Soil spatial patterns analysis at the ancient city of Ibida (Dobrogea, SE Romania), via portable X-ray fluorescence spectrometry and multivariate statistical methods

In this study we investigated the potential usefulness of multi-elemental soil analysis, obtained by a portable XRF spectrometer, to recognize ancient anthropogenic features, compared to the natural context on the territory of Roman-Byzantine Ibida city (Dobrogea, SE Romania). Soil samples were collected from 16 soil profiles and 2 archaeological excavations, from each soil horizon and cultural layer. Pearson correlation matrix of topsoil elements showed significant correlations among the various geogenic elements such as Ti, Fe, Mn, Zr, Ba and Cr. In the case of P, a strong correlation was found with Ca, a lower correlation with K, and no significant correlation with the other elements. Also, Cu and Zn behave differently, showing no significant correlation with any of the elements. Principal components analysis (PCA) and agglomerative hierarchical clustering (AHC) were carried out in order to identify groups of inter-correlated variables and assess the degree of association among soil profiles. The correlation between soil elements and the principal components suggest the presence of three groups which were defined as the geogenic, archaeo-anthropogenic and agro-anthropogenic component. Spatial distribution of topsoil elements was mapped by geostatistical methods in order to see if their spatial patterns reveal the influence of human activities. Although the results show that certain elements such as Ca, P and K present higher concentrations in the Ibida fortress area, we found that the interpretation of multi-elemental composition of the topsoil only is not sufficient for an accurate identification of the ancient characteristics which can be linked to the Roman-Byzantine period. Hence, we wanted to know if the presence of archaeological sites could be revealed by higher variation degree of soil elemental data along the profile depth. Therefore, we tested the utility of a synthetic statistical index, namely the variation coefficient, which was computed for each soil profile using all the available data. The results showed that if the index was standardized according to profile depth, then it became a useful indicator for the presence of ancient human activities.