Extract Solution Research Articles

Extraction and In Vitro Skincare Effect Assessment of Polysaccharides Extract from the Roots of Abelmoschus manihot (L.).

Obtaining high-added value compounds from agricultural waste receives increasing attention, as it can both improve resource utilization efficiency and reduce waste generation. In this study, polysaccharides are extracted from the discarded roots of Abelmoschus manihot (L.) by the high-efficiency ultrasound-assisted extraction (UAE). The optimized condition was determined as solid-liquid ratio SL ratio = 1:20, temperature T = 30 °C and time T = 40 min, achieving an extraction yield of 13.41%. Composition analysis revealed that glucose (Glc, 44.65%), rhamnose (Rha, 26.30%), galacturonic acid (GalA, 12.50%) and galactose (Gal, 9.86%) are the major monosaccharides of the extract. The extract showed a low degree of esterification (DE) value of 40.95%, and its Fourier-transform infrared (FT-IR) spectrum exhibited several characteristic peaks of polysaccharides. Inspired by the wide cosmetic applications of polysaccharides, the skincare effect of the extract was evaluated via the moisture retention, total phenolic content (TPC) quantification, 2,2-Diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging activity, anti-hyaluronidase and anti-elastase activity experiments. The extract solutions demonstrated a 48 h moisture retention rate of 10.75%, which is superior to that of commercially available moisturizer hyaluronic acid (HA). Moreover, both the TPC value of 16.16 mg GAE/g (dw) and DPPH-free radical scavenging activity of 89.20% at the concentration of 2 mg/mL indicated the strong anti-oxidant properties of the extract. Furthermore, the anti-hyaluronidase activity and moderate anti-elastase activity were determined as 72.16% and 42.02%, respectively. In general, in vitro skincare effect experiments suggest moisturizing, anti-oxidant, anti-radical and anti-aging activities of the A. manihot root extract, indicating its potential applications in the cosmetic industry.

Effect of rare earth elements Ce and Yb on the in vitro properties of biodegradable Zn alloys

Biodegradable pure Zn and zinc alloys have received much attention in recent years, but the mechanical properties, corrosion behavior and biocompatibility of the previous reported pure zinc and zinc alloys do not fully meet the clinical requirements. Alloying and deformation technology are widely used in improving the properties of biodegradable pure Zn and zinc alloys. In this work, we have developed two new types of binary zinc alloys with the two rare earth elements (REE) cerium (Ce) and ytterbium (Yb). The effects of Ce and Yb on the microstructure, mechanical properties, corrosion behavior, in vitro biocompatibility of biodegradable Zn-xCe and Zn-xYb (x = 0.1, 0.2, 0.5, 1.0 wt %) were systematically investigated. The ultimate tensile strength, yield strength and elongation of Zn-xCe and Zn-xYb alloys are significantly improved compared with pure Zn. The Zn-xCe and Zn-xYb alloys have superior antibacterial properties The osteoblast MC3T3-E1 cells exhibited excellent cell activity with polygonal or fusiform extension and adhesion cultured in the series of Zn-xCe and Zn-xYb alloys’ extract solutions, indicating the good in vitro biocompatibility of Zn-xCe and Zn-xYb alloys. This work demonstrated that the Zn-xCe and Zn-xYb binary alloys have great potential as new biodegradable metals for future biomedical implants and devices.

Bio-screening and quantification of methyl paraben in vinegar and coconut juice separated by HPTLC

As a widely used food preservative, methyl paraben was experimentally evidenced with serious hormone-like adverse effects. Herein, a high performance thin-layer chromatography platformed bioluminescent bioautography and image analysis for the selective quantification and confirmation of methyl paraben was proposed and validated in vinegar and coconut juice. First, the detectability of the bioautography to the analyte on different layer materials was estimated, revealing that normal silica gel was the best choice. After that, the liquid of sample extract and working solution were separated to overcome the background noises due to co-extracted matrices. The separation result was then coupled to the optimized bioautography, enabling instant and straightforward screening of the targeted compound. For accurate quantification, bioluminescent inhibition pattern caused by the analyte was processed by image analysis, giving useful sensitivity (LOD > 16 mg/kg), precision (RSD < 10.1 %) and accuracy (spike-recovery rate 76.9 %–112.2 %). Finally, the suspected result was confirmed by determining its MS fingerprint, further strengthening the reliability of screening.

Ameliorative effect of licorice extract against the detrimental effect of glyphosate-based pesticide: Toxicity and health

This study sheds the light on the potential of licorice (Glycyrrhiza glabra) root aqueous extract as a cornerstone for mitigating and detoxifying the residues of the widely used agricultural Glyphosate-based pesticides (GBPs). This study examined the GBPs toxic effects on kidney, liver, thyroid functions, and apoptosis using 50 adult male albino rats. All rats were divided into 5 groups, with 10 each. Control: served as untreated rats. GBP: rats were treated with 1 mL glyphosate solution 24 % orally for three weeks. The glyphosate-treated rats were gavaged with licorice root aqueous extractsolution (100, 200, and 300 mg/mLdistilled water, respectively) daily for three weeks. Licorice root aqueous extract solution (300 mg/mL distilled water) yielded notable reductions in liver, kidney enzymes, albumin, and AFP levels within the serum. Immunological tests, including immunohistochemical evaluations of caspase-3 and TNF-α expressions revealed a dose-dependent attenuation of apoptosis and inflammation with licorice intervention. This will provide a valuable perspective for agricultural practices future and paving the way for a more sustainable approach for using GBPs in animal agriculture industries.

Research and Application of Key Vocabulary Extraction Algorithm in English Vocabulary Learning

An effective key vocabulary extraction is significant for English Language Learning, assisting the learners to achieve proficiency in English. However, the process of vocabulary extraction is often challenging and multifaceted, leading to inaccurate vocabulary acquisition, which reduces the learner's proficiency. To address these issues, we presented a novel key vocabulary extraction using the combination of Radial Basis Function Neural Network (RBFNN) and Emperor Penguin Optimizer (EPO). The primary objective of this research is to identify the most relevant vocabulary from the huge English language corpus to assist learners in improving their proficiency levels and learning process. The proposed work commences with the collection of English corpus and the collected database undergoes pre-processing steps like tokenization, stop word removal, and stemming to improve the efficiency of subsequent analysis. Then, the developed EPO-RBFNN was designed to extract the most informative and relevant features from the pre-processed database. The RBFNN module was trained using the pre-processed database to learn and capture the semantic patterns and interconnections within the corpus, while the EPO was employed for selecting the vocabulary sequence considering their relevance and importance in English learning. The proposed framework was implemented in the Python tool, and the results are evaluated in terms of accuracy, precision, recall, and f-measure. Furthermore, a comparative assessment was made with existing vocabulary extraction methodologies to validate the outcomes. The comparative analysis showcases that the proposed strategy outperformed the conventional models, making it a suitable solution for key vocabulary extraction.

Rare earth element enrichment in coal and coal-adjacent strata of the Uinta Region, Utah and Colorado

This study aims to quantify rare earth element enrichment within coal and coal-adjacent strata in the Uinta Region of central Utah and western Colorado. Rare earth elements are a subset of critical minerals as defined by the U.S. Geological Survey. These elements are used for a wide variety of applications, including renewable energy technology in the transition toward carbon-neutral energy. While rare earth element enrichment has been associated with Appalachian coals, there has been a more limited evaluation of western U.S. coals. Here, samples from six active mines, four idle/historical mines, four mine waste piles, and seven stratigraphically complete cores within the Uinta Region were geochemically evaluated using portable X-ray fluorescence (n = 3,113) and inductively coupled plasma-mass spectrometry (n = 145) elemental analytical methods. Results suggest that 24%–45% of stratigraphically coal-adjacent carbonaceous shale and siltstone units show rare earth element enrichment (&amp;gt;200 ppm), as do 100% of sampled igneous material. A small subset (5%–8%) of coal samples display rare earth element enrichment, specifically in cases containing volcanic ash. This study proposes two multi-step depositional and diagenetic models to explain the enrichment process, requiring the emplacement and mobilization of rare earth element source material due to hydrothermal and other external influences. Historical geochemical evaluations of Uinta Region coal and coal-adjacent data are sparse, emphasizing the statistical significance of this research. These results support the utilization of active mines and coal processing waste piles for the future of domestic rare earth element extraction, offering economic and environmental solutions to pressing global demands.

A colorimetric sensor based on 4-MPBA Au@AgNPs for accurately identification of EnshiYulu tea grade

Enshi Yulu green tea (ESYL) is the most representative traditional steamed green tea in Enshi, Hubei. Different ESYL grades exhibit distinct flavors, tastes, and prices. In this study, a visual sensor based on 4-MPBA Au@AgNPs was developed for the rapid and accurate identification of ESYL grades. The recognition mechanism involved the binding of 4-MPBA Au@AgNPs with polyphenolic compounds in ESYL to form borate esters and the conversion of Ag+ to Ag0, with the generated Ag0 depositing on the surface of 4-MPBA Au@AgNPs. The results showed that the sensor can amplify the color differences of different grades of ESYL. The visual results were also validated by the partial least squares discriminant analysis model, demonstrating an enhancement in recognition accuracy from 68.2 % to 95.5 % compared to the original extraction solution. The colorimetric sensor developed in this study is expected to provide a new approach for traceability research of other foods.

Optimization of extraction, separation and purification of baicalin in Scutellaria baicalensis using response surface methodology

Optimizing extraction, separation, and purification processes of bioactive ingredients improves resource utilization and reduces environmental pollution in pharmaceutical industry. Here, we report findings of a study focusing on enhancing baicalin production from Scutellaria baicalensis, an important medicinal crop with increasing market demand. Using response surface methodology, we optimized ultrasonic-assisted extract method (ethanol concentration, ultrasonic temperature, ultrasonic time) for dried powder and decocting method (liquid-solid ratio, decocting time, decocting times) for fresh slices, respectively. Baicalin was separated, purified, and refined through the processing of macroporous resin, alkali-solution, acid precipitating and methanol reflux, respectively, and was quantified via high performance liquid chromatography. The main findings were as follows: (1) Optimal extraction of dried-powder: particle size 80 mesh, liquid-solid ratio 20:1, extraction solvent ethanol 57%, ultrasonic temperature 68°C, ultrasonic time 66 min. (2) Optimal extraction of fresh slices: adding the fresh slices into boiling water, liquid-solid ratio 43:1, decocting for 93 min. (3) Optimal separation: AB-8 macroporous resin, diameter to height ratio 1:15, loading liquid baicalin concentration 25.6 mg/mL, flow rate 1 BV/h, loading volume 8 BV, and elution volume 11 BV. (4) Optimal purification: adjusting the extraction solution pH to 1.0, static placing at 80°C for 12 h, washing the precipitate twice, dissolving the crude baicalin extract with alkali NaOH, and re-precipitating with stronger acid HCl. (5) Optimal refinement: reflux extracting the above baicalin extraction with 75% methanol for 30 min at liquid-solid ratio 15:1. Collectively, these findings provide valuable references for optimizing processing conditions of important medicinal crops in pharmaceutical industry.

Bioactive dry extract production from Hymenaea courbaril L. bark via spouted bed drying

AbstractThe work aims to develop and optimize a powdered phytopharmaceutical product from the stem bark of Hymenaea courbaril L. (jatobá) by the spouted bed drying. The study commenced with the extraction of bioactive compounds present in the plant raw material by dynamic maceration using ethanol/water 70% (v/v) at a temperature of 50°C for 60 min, for the ratio stem bark: solvent mass of 1:10 (w/w). The extract quality was assessed by quantifying chemical markers via spectrophotometry (total polyphenols and tannins) and through antioxidant activity by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay. The extractive solution was concentrated, added with drying adjuvant, and submitted to spouted bed drying. Product quality was evaluated by moisture content (Xp), water activity (aW), powder diameter, total polyphenols, and tannins content (PT and TT), and antioxidant activity, expressed as the extract concentration needed to reduce 50% of the DDPH radical (IC50). Spouted bed drying performance was evaluated through the drying yield (REC), product accumulation (Ac), and thermal efficiency (η). The optimal processing conditions were: inlet gas temperature, Tgi: 150°C, the ratio of the mass feed flow rate of the concentrated extract to the evaporation capacity of the dryer, Ws/Wmax: 45%, and the drying gas flow rate relative to minimum spouting, Q/Qms: 1.85. Under these conditions, it is predicted to obtain a dried extract with Xp = 4.9% w/w, PT = 26.0% w/w, REC = 77.7% w/w, η = 44.3%, and Ac = 10% w/w, with adequate values of aW, TT, and high antioxidant activity.

Statistical optimization of two-phase hollow fiber liquid-phase microextraction for preconcentration of strychnine in the clinical and postmortem biological fluids prior to gas chromatography-mass spectroscopy detection

Strychnine is a herbal alkaloid whose role in military and doping applications as well as the nervous system stimulation and cancer therapy has been confirmed. Because of its lethal nature, even at low dosages, developing a rapid, sensitive, and accurate method for determination of this alkaloid in the clinical and postmortem samples is of great importance. In this study, a green analytical method based on the two-phase hollow fiber liquid-phase microextraction (HF-LPME) combined with gas chromatography-mass spectrometry (GC–MS) was presented for preconcentration and determination of strychnine in biological fluids. A Box-Behnken design (BBD) with three variables, including extraction time (30–90 min), solution pH (9.0–11.0), and ionic strength (1.0–3.0 mol/L) was employed to maximize the extraction efficiency of strychnine by 1-octanol. The results were satisfactorily fitted to a quadratic response surface model (R2 = 0.979, F = 34.4) which predicted the optimum conditions of operation (extraction time of 89 min, pH = 11.0, and ionic strength of 3.0 mol/L). Based on the results, the studied variables and the interaction between pH and extraction time showed highly significant effects on the process efficiency. The calibration curve was linear in the concentration range of 2.7–1000.0 µg/L (R2 = 0.9978) and the limits of detection and quantitation were found to be 0.8 and 2.7 µg/L, respectively. Moreover, the method was successfully applied to different real samples, including urine (clinical sample), bile and stomach contents, blood, and vitreous humor (postmortem samples), and relative recoveries were obtained in the range of 93.8 % to 99.8 %. The findings of this study suggest that the environmentally friendly HF-LPME method which uses a small amount of a chlorine-free solvent, is a sensitive, cost-effective, simple, and efficient preconcentration method for trace determination of strychnine in biological fluids.

Tailoring exfoliated 2D Mo-PDA nanopetals as sustainable intelligent anti-corrosion nanoreservoir for upgrading the self-healing/barrier function of epoxy coatings

The present study unfurled novel route to tailor cutting-edge molybdenum-polydopamine (AHPDA) and molybdenum-polydopamine-Ce3+/4+ nanocarriers (AHPDA@Ce) using in-situ self-nucleophilic polymerization techniques and scrutinized their intelligent anti-corrosion and physicomechanical properties in solution and coating phases. The manageable emancipation of Ce3+/4+,MoO42-, polydopamine (PDA) derivatives from exfoliated AHPDA and AHPDA@Ce nanocarriers at the extract solutions brilliantly reduced the icorr from 5.14 to 2.22 and 1.45 µA/cm2, respectively. Afterward, the derivatives assembled intricate barrier films at the electrochemical active sites, outstandingly restricting the severe corrosion on steel panels immersed in AHPDA@Ce and AHPDA extract solutions. Moreover, even after 48 h immersion, not only did the scratched EAHC (containing AHPDA@Ce nanocarriers) and EAHM (including AHPDA nanocarriers) coatings exhibit superior self-healing protection by 382 % and 327 % promotion in RTotal towards NE coatings (neat epoxy), but also intelligent EAHC and EAHM coatings tolerated the salt spray condition up to 1000 h exposure rather than 400 h of NE coating. Also, the intact EAHC and EAHM coatings after 24 weeks of submersion with noteworthy log|Z|0.01Hz of 10.51 and 9.98 Ω cm2 showcased boosted barrier-passive function lifetime with respect to the NE coatings (5.68 Ω cm2). Furthermore, smart EAHM and EAHC nanocomposites flaunted lower adhesion loss of 2.3 and 5.2 times, respectively, as well as, an incredible 76.11 % and 31.50 % improvement in the reduction of cathodic peel-off area regarding the NE coating. Ultimately, smart EAHC and EAHM coatings could be employed as eco-friendly effective anti-corrosion coatings with terrific self-healing/barrier function and durable service life in strategic knowledge edge applications.

Development of a method to evaluate the effects of external environments on drug stability in nails using micro-segmental analysis.

Nails can be used as an alternative to hair for examining past drug use. However, daily hand-and-nail care can eliminate the internal drugs. Therefore, we developed an evaluation method to examine the effects of the external environment on drug stability in nails using micro-segmental analysis. First, reference nails containing drugs were prepared by collecting fingernails from participants who had consumed hay-fever medicines continuously for 4months. Next, the entire free edge of a reference nail was cut into halves at the centerline; one side was stored as an untreated block, and the other was treated with various hand/nail care products. Both nail blocks were washed and segmented at 0.5-mm intervals in the width direction. Each segment in the extraction solution was crushed with stainless-steel beads, sonicated, and soaked in the solution for 24 h. The analytes in extracts were quantified by LC-MS/MS, and the drug concentrations between the treated and untreated blocks were compared. The drug concentrations decreased slightly in nails treated with manicure and gel-nail products. The analytes in nails tended to be lower in water-rich products such as hand soap and hand cream than in oil-rich products such as nailcare oil and acetone-free remover. The developed method using micro-segmental analysis enabled the evaluation of the effects of various hand/nail care products on drug stability in a limited number of nails. This would also be useful for examining the effects of severe environments on drugs in nails collected from cases of unnatural death.

Determining flavonoids in the skin of Citrus reticulata

n this work we studied the flavonoid composition of tangerine skins using 10 kinds of tangerines from various producers. The tangerine skins were peeled from fruit purchased from the market in Belgorod and dried at room temperature outside direct sunlight. The compositions of “green” ethanol-based extraction solutions and the “weighed portion of plant material: volume of extraction solution” ratios were chosen for extraction to ensure a high yield of flavonoids. For separation, reverse-phase HPLC on the Kromasil 100-5C18 stationary phase was used in environmentally friendly mobile phase compositions that contained ethanol as an organic modifier. In gradient elution mode all mobile phases contained 0.2 vol. % orthophosphoric acid. To assign extract components, we used samples of a number of substances and parameters of electronic absorption spectra in comparison with published data. It was found that the chromatographic profiles of the extracts of the studied samples were noticeably different. A number of the least lipophilic compounds, derivatives of cinnamic acids, were found in all extracts. After that, we discovered two flavanone glycosides, the main of which was hesperidin (hesperitin-7-rutinoside) with a content of is 26.0-39.9 mg per 1 g of dried raw material, and naringin (naringenin-7-neohesperidiside) in significantly smaller quantities, from 0 to 1.15 mg per 1 g. But of greatest interest were polymethoxylated flavones, among which the main component was nobiletin (5,6,7,8,3′,4′-hexamethoxyflavone) with a content from 0.03 to almost 11 mg/g in dried peel and tangeretin (5,6,7,8,4′-pentamethoxyflavone), found in slightly smaller quantities, 0.1-5.4 mg/g. It was established that nobiletin and tangeretin were mostly accumulated in the skins of small tangerines. On the whole, tangerine skin is a great source of highly biologically active flavonoids, so its processing is an important task for the food industry.

Extraction of Copper from Pregnant Leach Solution (PLS) and Reduction of Crud Formation

ABSTRACT Presented universal recommendations for the reduction of crud formation, reviewing various aspects affecting the loss of diluent and extractant due to the formation of a third phase (crud), encountered in many hydrometallurgical plants using copper solvent extraction. In this paper introduce the reasons of the crud formation , description of the stable emulsions containing solid particles and choice of technological scheme. An analysis of operations to be considered in the operation of copper solvent extraction plants is presented, due to the deterioration of copper grade below 0.5% in ore and the increase in aluminum content up to 20–25%. Results of use of extraction properties of modified extractants of ACCORGA series and unmodified extractant Lix984N on pregnant leached solution of the most important deposits (Almaly and Aktogay) are given. It is established that for solutions of Almaly deposit, ACCORGA5640 and unmodified Lix984 extractants have high selectivity to copper. Distribution of iron, silica, and copper ions during extraction was studied, and it was found that high selectivity to copper/iron and copper/silica is possessed by extractant Lix 984N, ACCORGA5640. It was found that for solutions of the Aktogay deposit, the ratio of interphase suspension in both extractants is the same, and phase separation in experiments with the use of extractant Lix 984N was 10 s shorter with the use of extractant ACCORGA5640. It was found that the addition of ACCORGACR60 reagent in the amount of 5-10 ppm also leads to a decrease in the volume of crud by 13%, for a stronger suppression of crud.

Solid Phase Extraction Methodology for Robust Isotope Analysis of Atmospheric Ammonium.

The stable nitrogen isotope composition (δ15N) of atmospheric ammonia (NH3) and ammonium (NH4+) has emerged as a potent tool for improving our understanding of the atmospheric burden of reduced nitrogen. However, current chemical oxidation methodologies commonly utilized for characterizing δ15N values of NH4+ samples have been found to lead to low precision for low concentration (i.e., < 5 μmol L-1) samples and often suffer from matrix interferences. Here, we present an analytical methodology to extract and concentrate NH4+ from samples through use of a sample pretreatment step using a solid phase extraction technique involving cation exchange resins. Laboratory control tests indicated that 0.4 g of cation exchange resin (Biorad AG-50W) and 10 mL of 4 M sodium chloride extraction solution enabled the complete capture and removal of NH4+. Using this sample pretreatment methodology, we obtained accurate and precise δ15N values for NH4+ reference materials and an in-house quality control sample at concentrations as low as 1.0 μM. Additionally, the sample pretreatment methodology was evaluated using atmospheric aerosol samples previously measured for δ15N-NH4+ (from Changdao Island, China), which indicated an excellent δ15N-NH4+ match between sample pretreatment and no treatment (y = (0.98 ± 0.05)x + (0.11 ± 0.6), R2 = 0.99). Further, this methodology successfully extracted NH4+ from aerosol samples and separated it from present matrix effects (samples collected from Oahu, Hawaii; pooled standard deviation δ15N-NH4+ = ± 0.5‰,n = 16 paired samples) that without pretreatment originally failed to quantitatively oxidize to nitrite for subsequent δ15N isotope analysis. Thus, we recommend applying this sample pretreatment step for all environmental NH4+ samples to ensure accurate and precise δ15N measurement.

Preparation of ultra-sensitive anti-carbendazim antibodies based on new haptens and their application in lateral flow immunoassay

To overcome limitations with respect to the low sensitivity of rapid immunoassay methods due to dilution of the extract in extraction solution, ultra-sensitive antibodies are needed. The linker-tethering site between the target and carrier protein, the length of the spacer arm, and the atomic charge of the linker-tethering site between the target and spacer arm in haptens design play a pivotal role in the preparation of ultra-sensitive antibodies. In this study, carbendazim (CBZ), a systemic broad-spectrum fungicidal pesticide, was used as model compound. 2-Aminobenzimidazole was chosen as the common skeletal structure and reacted with different groups, such as alkanes and urine groups, to form haptens H1 (previously reported), H2 (novel), and H3 (novel), respectively. Subsequently, eight monoclonal antibodies (mAbs) were generated using these three haptens, which exhibited notable variation in sensitivity. The half maximal inhibitory concentration (IC50) value of mAb 4B11 based on hapten H3 against CBZ was 0.04 ng/mL, which was seven times better than that of mAb 5B10 (IC50 value of 0.28 ng/mL) prepared using hapten H2 and 129 times better than that of mAb 6D5 (IC50 value of 5.15 ng/mL) prepared using hapten H1. Finally, the optimal antigen–antibody combination was employed to establish a sensitive colloidal gold lateral flow immunoassay (CG-LFA) for CBZ detection in vegetables and fruits with convenient sample pretreatment. The developed CG-LFA shows promising practical utility and prospects for application due to its low limit of detection (0.10–0.18 ng/mL) and high recovery ratios (76.0%–96.1%) in six different samples.

Efficacy of propolis extract and eye drop solutions to suppress encystation and excystation of Acanthamoeba triangularis WU19001-T4 genotype

Background Propolis is a natural resinous product from a variety of plants and combines it with beeswax and salivary enzymes to create bee glue. Its potentials have been employed in the treatment of many diseases and conditions for centuries. This study, therefore, aims to determine the anti-Acanthamoeba properties of the propolis extract, eye drops coupled to some mechanisms such as inhibition of encystation and excystation. Methods The minimum inhibitory concentrations (MICs) of the most active propolis extract were assessed in trophozoites and cysts of Acanthamoeba triangularis (A. triangularis) at 0.256 and 1 mg/mL, respectively. Results Active eye drops inhibited trophozoites and cysts with a MIC value of 100%. At concentrations lower than their MICs values (1/2–1/16 MIC), propolis and eye drops revealed inhibition of encystation. In addition, at 1/2 MIC, both the propolis extract and eye drops showed potential inhibition of excystation. In combined sets of propolis extract and eye drops, they showed slightly increasing inhibition of encystation and excystation. Surprisingly, the MIC of chlorhexidine decreased when combined with the propolis and eye drops. SEM and TEM images displayed morphological changes in A. triangularis treated with combined sets of propolis extract and eye drops. Conclusion From this study, a new combined eye drop solution with propolis extract was found to be helpful in reducing encystation and excystation in A. triangularis. Therefore, this combination is an alternative for the treatment of eye diseases in early stages along with reducing the entry into the cyst stage of Acanthamoeba. The results of this study revealed new anti-Acanthamoeba inhibitors with promising combined alternative therapeutic potential for the treatment of Acanthamoeba keratitis.

Determination of 12 prohibited veterinary drug residues in pig urine by ultra high performance liquid chromatography-tandem mass spectrometry

A method was established for the simultaneous detection of 12 prohibited veterinary drugs, including β2-receptor agonists, nitrofuran metabolites, nitroimidazoles, chlorpromazine, and chloramphenicol, in pig urine. The sample was pretreated by enzymolysis, acid hydrolysis/derivatization, and liquid-liquid extraction combined with solid-phase extraction. Detection was performed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Ammonium acetate solution (0.2 mol/L, 4.5 mL) and β-glucuronidase/aryl sulfatase (40 μL) were added to the sample, which was subsequently enzymolized at 37 ℃ for 2 h. Then, 1.5 mL of 1.0 mol/L hydrochloric acid solution and 100 μL of 0.1 mol/L o-nitrobenzaldehyde solution were added to the sample. The mixture was incubated at 37 ℃ for 16 h, and the analytes were extracted with 8 mL of ethyl acetate by liquid-liquid extraction. The lower aqueous phase obtained after extraction was extracted and purified using a mixed cation-exchange solid-phase extraction column. The extracts were combined, the extraction solution was blow-dried with nitrogen, and the residue was redissolved for determination. The samples were analyzed under multiple-reaction monitoring mode with both positive and negative electrospray ionization, and quantified using an isotope internal standard method. The correlation coefficients (r) of the 12 compounds were >0.99. The limits of detection (LODs) and quantification (LOQs) of chloramphenicol were 0.05 and 0.1 μg/L, respectively, and the LODs and LOQs of the other compounds were 0.25 and 0.5 μg/L, respectively. The mean recoveries and RSDs at 1, 2, and 10 times the LOQ were 83.6%-115.3% and 2.20%-12.34%, respectively. The proposed method has the advantages of high sensitivity, good stability, and accurate quantification; thus, it is suitable for the simultaneous determination of the 12 prohibited veterinary drug residues in pig urine.

Rapid determination of 15 N-nitrosamines in air-dried yak meat using one-step QuEChERS-gas chromatography-triple quadrupole mass spectrometry

A method based on gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) coupled with one-step QuEChERS technique was developed for the simultaneous determination of 15 N-nitrosamines in air-dried yak meat. The hydration volume, extraction solvent, extracting salt, and cleaning material were optimized according to the characteristics of the N-nitrosamines and sample matrix. The optimized conditions were as follows: 10 mL of purified water for sample hydration, acetonitrile as the extraction solvent for the sample after hydration, 4.0 g of anhydrous MgSO4 and 1.0 g of NaCl as extracting salts, 500 mg of MgSO4+25 mg of C18+50 mg of PSA as cleaning materials. Favorable recoveries of the 15 N-nitrosamines were obtained when the extraction solution was incompletely dried. Thus, the final extract was dried to below 0.5 mL under a mild nitrogen stream and then redissolved to 0.5 mL with acetonitrile. After filtration, 200 μL of the sample was transferred to an autosampler vial for GC-MS/MS analysis. The 15 N-nitrosamines were determined using GC-MS/MS on a DB-HeavyWAX column (30 m×0.25 mm×0.25 μm) with an electron impact ion source in multiple-reaction monitoring (MRM) mode, and quantified using an external standard method. Under the optimized experimental conditions, the results showed that the calibration curves exhibited good linearities for the 15 N-nitrosamines, with correlation coefficients (r2) greater than 0.9990. The limits of detection (LODs) and the limits of quantification (LOQs) ranged from 0.05 to 0.20 μg/kg and from 0.10 to 0.50 μg/kg, respectively. At spiked levels of 1LOQ, 2LOQ, and 10LOQ, the average recoveries were 79.4%-102.1%, 80.6%-109.5%, and 83.0%-110.6%, respectively, and the relative standard deviations were in the range of 0.8%-16.0%. The low matrix effects of the 15 N-nitrosamines indicated the high sensitivity of the proposed method. The method was applied to detect representative commercial air-dried yak meat samples obtained using different processing techniques. Seven N-nitrosamines, including N-nitrosodimethylamine, N-nitrosodiisobutylamine, N-nitrosodibutylamine, N-methyl-N-phenylnitrous amide, N-ethyl-N-nitrosoaniline, N-nitrosopyrrolidine, and N-nitrosodiphenylamine were detected in all samples. The average contents of the seven N-nitrosamines was 0.08-20.18 μg/kg. The detection rates and average contents of the N-nitrosamines in cooked air-dried yak meat samples were higher than those in traditional raw air-dried yak meat samples. Compared with the manual QuEChERS method, the one-step QuEChERS method developed integrated the extraction and clean-up procedures into one single run, and the detection efficiency was considerably improved. The developed method is simple, rapid, highly sensitive, and insusceptible to human errors. Thus, it is useful for the determination of N-nitrosamines in air-dried yak meat and can be extended to the qualitative and quantitative analysis of N-nitrosamines in other meat products. It also provides method support and a data reference for the general determination of N-nitrosamines, which is of great significance for food safety.

Machine vision-based online detection method for color characteristics of cobalt extraction solution

Cobalt, as a rare metal, plays an important role in strategic resources due to its physical, chemical, and mechanical properties in applications. In order to achieve automatic control of the cobalt extraction process, it is necessary to conduct online detection of the color characteristics of the cobalt extraction solution. Unfortunately, due to the lack of online automatic detection methods for the color of cobalt extraction solution, the automatic control of the extraction process has not yet been achieved. Currently, the color of cobalt extraction solution needs to be observed and judged by operators based on experience. This will result in significant detection errors and time lag. To change this situation, an online detection method for color features of cobalt extraction solution based on machine vision is proposed in this article. Firstly, we establish a real-time image acquisition environment for detecting object colors, and then use the Gaussian filters and K-means algorithm to denoise and segment the image. In order to correct color distortion in images caused by ambient light, we measure the color feature values of a set of standard color cards using the machine vision system and a standard spectrophotometer. Based on this test data, we establish chromaticity correction models for the extraction solution using back propagation (BP) network and radial basis function (RBF) network, respectively. The models can correct the color characteristic values of the extraction solution, overcome environmental interference, and thus obtain more accurate color characteristic values of the extraction solution. The established model can be used for online automatic color detection of cobalt extraction solution. The modeling results indicate that in the established color measurement environment, the RBF network model outperforms the BP network model in color feature detection accuracy.