Determination of microplastics in agricultural soil by double-shot pyrolysis-gas chromatography combined with two-step extraction.

A method for the determination of five microplastics in agricultural soil was established by double-shot pyrolysis-gas chromatography combined with two-step extraction. First, polycarbonate (PC), polystyrene (PS), polypropylene (PP), and polyethylene (PE) were extracted from soil samples using a mixed solvent of cyclohexanone and p-xylene, and then PE terephthalate was extracted with m-methylphenol. Subsequently, PC and PE terephthalate were analyzed by thermochemolysis, and PE, PP, and PS were investigated by direct pyrolysis at 600°C. The linearity of the method was satisfactory for five microplastics and the correlation coefficients were higher than 0.97 in the respective concentration range. The limits of detection and the limits of quantification were 0.2-10.0 and 0.5-20.0 µg/g, respectively. The method provided recoveries of 75.1%-141.5%, with acceptable repeatability within 20.0%. It was a supplementary method for the existing characterization of microplastics in agricultural soil.

The BIORES-21 Survey: Insights Into Remote and Online Education in Biomechanics and Mechanobiology.

The COVID-19 pandemic necessitated mainstream adoption of online and remote learning approaches, which were highly advantageous yet challenging in many ways. The online modality, while teaching biomedical engineering-related topics in the areas of biomechanics, mechanobiology, and biomedical sciences, further added to the complexity faced by the faculty and students. Both the benefits and the challenges have not been explored systematically by juxtaposing experiences and reflections of both the faculty and students. Motivated by this need, we designed and conducted a systematic survey named BIORES-21, targeted toward the broader bio-engineering community. Survey responses and our inferences from survey findings cumulatively offer insight into the role of employed teaching/learning technology and challenges associated with student engagement. Survey data also provided insights on what worked and what did not, potential avenues to address some underlying challenges, and key beneficial aspects such as integration of technology and their role in improving remote teaching/learning experiences. Overall, the data presented summarize the key benefits and challenges of online learning that emerged from the experiences during the pandemic, which is valuable for the continuation of online learning techniques as in-person education operations resumed broadly across institutions, and some form of online learning seems likely to sustain and grow in the near future.

Analysis of A1-type and A2-type ß-casein in Maiwa Yak and Pien-niu milk by HPLC-high-resolution MS and tandem MS.

In this study, a peptide-based method employing ultra high performance liquid chromatography electrostatic field orbitrap high-resolution mass spectrometry and triple quadrupole mass spectrometry was developed for quantification of A1-type and A2-type ß-casein in milk from Yak, cows, and their offspring of crosses, Pien-niu. The specific peptides of A1-type and A2-type ß-casein were screened and confirmed by protein software after analysis of high-resolution mass spectrometry. The multiple reaction monitoring method was established based on the qualitative results, and isotope-label peptides were used as internal standards. The linear correlation coefficients of this method were >0.99. The relative standard deviations of repeatability test were 0.2-3.6%. The recovery rate ranged from 93.3 to 114.4% with relative standard deviations <6% at three different spiking levels. The method was applied to analyze 45 milk samples from different species. The results showed that ß-casein in Yak and Pien-niu milk was about 30% higher than that in cow milk. Furthermore, the ß-casein in the Yak milk only contains A2-type ß-casein. A1-type and A2-type ß-casein coexist in most samples of Pien-niu and cow milk, a few samples contain only one type of ß-casein. These results provide further understanding in nutritional value of milk from Yak and Pien-niu.

Optimized plant compound with potent anti-biofilm activity across gram-negative species.

Many human diseases, including cystic fibrosis lung infections, are caused or exacerbated by bacterial biofilms. Specialized modes of motility, including swarming and twitching, allow gram-negative bacteria to spread across surfaces and form biofilms. Compounds that inhibit these motilities could slow the spread of biofilms, thereby allowing antibiotics to work better. We previously demonstrated that a set of plant-derived triterpenes, including oleanolic acid and ursolic acid, inhibit formation of Escherichia coli and Pseudomonas aeruginosa biofilms, and alter expression of genes involved in chemotaxis and motility. In the present study, we have prepared a series of analogs of oleanolic acid. The analogs were evaluated against clinical isolates of E. coli and P. aeruginosa in biofilm formation assays and swarming assays. From these analogs, compound 9 was selected as a lead compound for further development. Compound 9 inhibits E. coli biofilm formation at 4 µg/mL; it also inhibits swarming at ≤1 µg/mL across multiple clinical isolates of P. aeruginosa, E. coli, Burkholderia cepacia, and Salmonella enterica, and at <0.5 µg/mL against multiple agricultural strains. Compound 9 also potentiates the activity of the antibiotics tobramycin and colistin against swarming P. aeruginosa; this is notable, as tobramycin and colistin are inhaled antibiotics commonly used to treat P. aeruginosa lung infections in people with cystic fibrosis. qPCR experiments suggested that 9 alters expression of genes involved in regulating Type IV pili; western blots confirmed that expression of Type IV pili components PilA and PilY1 decreases in P. aeruginosa in the presence of 9.

Design, synthesis and evaluation of oxime-functionalized nitrofuranylamides as novel antitubercular agents.

A series of oxime-functionalized nitrofuranylamides were designed, synthesized and evaluated for their in vitro anti-mycobacterial activities against MTB H37Rv and drug-resistant clinical isolates. Among them, two compounds 7a and 7b exhibited excellent activity against the three tested strains. Both of them were comparable to the first-line anti-TB agents INH and RIF against MTB H37Rv, and were far more potent than INH and RIF against MDR-TB 16833 and 16995 strains. Thus, both of them could act as leads for further optimization.

A Total Synthesis of Bifidenone.

The first total synthesis of bifidenone, a novel natural tubulin polymerization inhibitor, has been achieved in 12 steps starting from commercially available 1,4-dioxaspiro[4.5]decan-8-one. The synthesis includes a newly developed method to generate the dihydrobenzodioxolone core by palladium-catalyzed aerobic dehydrogenation. The three stereocenters were installed with an AD-mix-ß dihydroxylation step followed by a late-stage palladium-catalyzed decarboxylation-allylation procedure. The absolute stereochemistry of 3 was determined via 13a by single-crystal X-ray analysis.

Rapid determination of ginkgolic acids in Ginkgo biloba kernels and leaves by direct analysis in real time-mass spectrometry.

A novel method based on direct analysis in real time integrated with mass spectrometry was established and applied into rapid determination of ginkgolic acids in Ginkgo biloba kernels and leaves. Instrument parameter settings were optimized to obtain the sensitive and accurate determination of ginkgolic acids. At the sample introduction speed of 0.2 mm/s, high intensity of [M-H]- ions for ginkgolic acids were observed in the negative ion mode by utilization of high-purity helium gas at 450°C. Two microliters of methanol extract of G. biloba kernels or leaves dropped on the surface of Quick-Strip module was analyzed after solvent evaporated to dryness. A series of standard solutions of ginkgolic acid 13:0 in the range of 2-50 mg/L were analyzed with a correlation coefficient r = 0.9981 and relative standard deviation (n = 5) from 12.5 to 13.7%. The limit of detection was 0.5 mg/L. The results of direct analysis in real time-mass spectrometry were in agreement with those observed by thermochemolysis gas chromatography. The proposed method demonstrated significant potential in the application of the high-throughput screening and rapid analysis for ginkgolic acids in dietary supplements.

Analysis of volatile organic compounds in pleural effusions by headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry.

Headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry was applied to the analysis of volatile organic compounds in pleural effusions. The highly volatile organic compounds were separated successfully with high sensitivity by the employment of a cryotrap device, with the construction of a cold column head by freezing a segment of metal capillary with liquid nitrogen. A total of 76 volatile organic compounds were identified in 50 pleural effusion samples (20 malignant effusions and 30 benign effusions). Among them, 34 more volatile organic compounds were detected with the retention time less than 8 min, by comparing with the normal headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry method. Furthermore, 24 volatile organic compounds with high occurrence frequency in pleural effusion samples, 18 of which with the retention time less than 8 min, were selected for the comparative analysis. The results of average peak area comparison and box-plot analysis showed that except for cyclohexanone, 2-ethyl-1-hexanol, and tetramethylbenzene, which have been reported as potential cancer biomarkers, cyclohexanol, dichloromethane, ethyl acetate, n-heptane, ethylbenzene, and xylene also had differential expression between malignant and benign effusions. Therefore, the proposed approach was valuable for the comprehensive characterization of volatile organic compounds in pleural effusions.

Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ≥ 0.9990. The limits of detection were in the range of 0.67 to 1.51 µg/L, based on the signal-to-noise ratio of 3 and a 25 µL injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts.

Total synthesis of tricladins A and B and identification of their absolute configuration.

A concise synthesis of both (S)- and (R)-enantiomers of tricladins A and B from l-Boc alanine was achieved. The diastereomeric intermediates were separated by chiral column chromatography, and the absolute configuration of the 2-position was assigned by observed NOE interactions with the known stereogenic center at the 5-position. By comparison of all synthesized final enantiomers with the corresponding natural products, we concluded that the natural tricladins A and B must have the (R)-configuration.

Simultaneous determination of peroxydisulfate and conventional inorganic anions by ion chromatography with the column-switching technique.

The application of ion chromatography with the column-switching technique for the simultaneous analysis of peroxydisulfate and conventional inorganic anions in a single run is described. With this method, conventional inorganic anions were separated by consecutive elution through both the guard column and separation column, but peroxydisulfate that only passed through the guard column had a good peak shape and short retention time. A series of standard solutions consisting of target anions of various concentrations from 0.01 to 75 mg/L were analyzed, with a correlation coefficient (r) ≥ 0.9990. The limits of detection were in the range of 0.49-9.84 µg/L based on the S/N of 3 and a 25 µL injection volume. RSDs for retention time, peak area, and peak height were all <1.77%. A spiking study was performed with satisfactory recoveries between 97.6 and 103.4% for all anions. The quantitative determination of peroxydisulfate and conventional inorganic anions in surface waters was accomplished within 18 min by this column-switching technique.

Proposed clinical model for predicting speech outcomes in patients undergoing Furlow palatoplasty for velopharyngeal insufficiency after primary palatoplasty.

This study aimed to validate the predictors of speech outcomes following Furlow palatoplasty in patients with velopharyngeal insufficiency (VPI) after primary palatoplasty and to propose and validate a model to predict the risk of persistent VPI. The study included patients with VPI after primary palatoplasty who underwent Furlow palatoplasty as a secondary surgery. Eleven variables were included: velar length, pharyngeal cavity depth, velopharyngeal gap, velopharyngeal closure pattern, sex, presence of cleft lip, existence of palatal fistula, surgeon, age at primary palatoplasty, age at secondary surgery, and time interval between primary palatoplasty and secondary surgery. Postoperative speech outcomes were assessed at least 1 year after the secondary surgery and classified as velopharyngeal competence (VPC) or VPI. Variables were analyzed using multivariate logistic regression analysis, and the area under the curve (AUC) was used to validate model accuracy. The study sample comprised 101 patients. Of the patients, 62 had VPC and 39 had VPI after secondary surgery. The results showed a younger age at secondary surgery, a smaller velopharyngeal gap, being female, having a coronal velopharyngeal closure pattern and a velopharyngeal closure ratio of 90% or greater produced a greater probability of VPC. Given the constraints of this study, it appears that the Furlow palatoplasty should be prioritized when the clinical model predicts a substantial likelihood of VPC post-surgery.

Acylated anthocyanins from Dendrobium officinale Kimura & Migo: Structural characteristics, antioxidant and hypoglycemic activities.

Dendrobium officinale Kimura & Migo (D. officinale) has been widely used as Chinese medicine and functional food. In present study, the structural characteristics of anthocyanins in D. officinale were investigated by ultra-performance liquid chromatography with diode array detector (UPLC-DAD) and ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS/MS). Totally, 14 anthocyanins were detected and identified, and 13 of them were first reported in D. officinale. Results showed that the vast majority of anthocyanins had multi-glycosylated cyanidin core, with variable acylation pattern mainly comprising phenolic acids. The composition and content of anthocyanins in D. officinale stems with different cultivation modes and years have been compared. The anthocyanins showed potent antioxidant activity in terms of radicals scavenging capacity and reducing power, as well as superior α-amylase and α-glucosidase inhibitory activity. The results provided a complete profile of anthocyanins in D. officinale and laid a foundation for further utilizing them as functional foods.

Preparation of mixed-mode weak cation exchange magnetic solid-phase extraction sorbent and its application in the extraction of 21 illicit drugs from wastewater.

The detection of illicit drugs in wastewater can effectively monitor and evaluate the trend of illicit drug abuse. A novel mixed-mode cation exchange magnetic sorbent Fe3O4 @poly(ST/DVB/MA-COOH) was prepared and firstly applied as magnetically dispersed solid phase extraction material to efficiently, rapidly, and selectively extract 21 illicit drugs from wastewater. The selectivity of the sorbent was mainly attributed to the electrostatic interaction. The effects of Fe3O4 @poly(ST/DVB/MA-COOH) preparation and extraction conditions on the adsorption performance were thoroughly discussed. Among the 21 illicit drugs, the absolute extraction recovery values for 19 illicit drugs were greater than 80 % and the entire adsorption process could be achieved in one minute. Subsequently, the Fe3O4 @poly(ST/DVB/MA-COOH) sorbent combined with UHPLC-MS/MS was used to establish a quantitative method for the effectively extracted 19 illicit drugs in wastewater. The method had a good determination coefficient in the range of 0.2-200 ng/L and the limits of detection of the method were 0.03-0.67 ng/L. The spiked recovery values were in the range of 87.0-119.6 %. Finally, the method was successfully applied to the detection of 19 illicit drugs in wastewater samples and also compared with the commonly used SPE method. The obtained results indicate that Fe3O4 @poly(ST/DVB/MA-COOH) has great advantages in the detection of illicit drugs in wastewater.

A micro sample pretreatment technique combined with ion chromatography and its application in the determination of polyvinyl chloride.

A method for the determination of polyvinyl chloride was developed by the use of a micro sample pretreatment technique combined with ion chromatography. Polyvinyl chloride sample was placed in a sealed glass capillary containing 10 µL deionized water. As a micro pyrolysis reactor, the sealed glass capillary was maintained at 300 °C for 2 min in an oven. Under the above temperature, polyvinyl chloride was pyrolyzed rapidly and released hydrogen chloride, which was easily absorbed by deionized water. Subsequently, the absorption liquid was transferred to a volumetric flask and diluted to 10 mL. Ion chromatography was utilized to detect the content of chloride ion in the diluted absorption liquid for the quantification of polyvinyl chloride in samples. Good linear correlation coefficient (r = 0.9999) was obtained over a range of 0.02-2.00 mg polyvinyl chloride. Appropriate precision with the relative standard deviation below 16.4% and good recoveries between 86.0 and 119.4% were achieved in this work. The limits of detection and quantification were 0.004 mg and 0.012 mg for polyvinyl chloride respectively. The contents of polyvinyl chloride in real samples determined by the micro sample pretreatment technique were consistent with the results obtained by the referenced oxygen flask combustion method. It proved that the proposed method is simple, rapid and accurate for the determination of polyvinyl chloride in real samples.

Hollow fiber-solid phase microextraction of fatty acid methyl esters from wastewater coupled with micro sample collector assisted injection technique.

Hollow fiber-solid phase microextraction combined with micro sample collector assisted injection technique was developed for the detection of trace fatty acid methyl esters in biodiesel wastewater. Polypropylene hollow fiber was employed as extraction material to absorb fatty acid methyl esters in biodiesel wastewater. After the adsorption, hollow fiber was sleeved on the needle core of a micro sample collector and introduced directly into a GC injector for thermal desorption of the analytes. The selectivity of polypropylene hollow fiber on fatty acid methyl esters was investigated by extracting common pollutants in wastewater. Under the optimal conditions, the enrichment factors of polypropylene hollow fiber for methyl palmitate, methyl linoleate, methyl oleate, and methyl stearate were tested as high as 471, 287, 527, and 801, respectively. The quantitative method was validated and the linearity was satisfactory over a concentration range of 10-2000 µg/L with the correlation coefficients more than 0.9990 for 4 fatty acid methyl esters. The limits of detection and quantification were 0.04-0.40 µg/L and 10.0 µg/L, respectively. The recoveries were in the range of 92.0-116.7% by analyzing actual spiked samples. The results showed that the established method was suitable for the analysis of trace fatty acid methyl esters in water samples, with simple operation, low cost and environmental friendliness.

Structural characteristics, functional properties, antioxidant and hypoglycemic activities of pectins from feijoa (Acca sellowiana) peel.

The structure characteristics, functional properties, antioxidant and hypoglycemic activities of pectins extracted from feijoa peel with water (FP-W), acid (FP-A) and alkali (FP-B) were investigated. Results showed that the feijoa peel pectins (FPs) were mainly composed of galacturonic acid, arabinose, galactose and rhamnose. FP-W and FP-A had higher proportion of homogalacturonan domain, degree of esterification and molecular weight (for main component) than FP-B; FP-B owned the highest yield, protein and polyphenol contents. FP-W had a compact and smooth surface morphology unlike FP-A and FP-B. FP-W and FP-A had better thermal stability than FP-B. The rheological analysis suggested that the FPs exhibited pseudoplastic fluid behavior, and the elastic characteristics were dominant. Results showed that FP-W and FP-B had superior antioxidant and hypoglycemic activities than FP-A. According to correlation analysis, monosaccharide composition, sugar ratios and degree of acetylation were chief factors affecting the functional properties, antioxidant and hypoglycemic activities of the FPs.

Preparation and application of polystyrene-divinylbenzene sorbent with weak cation-exchange character for the selective extraction of illicit drugs in environmental water.

A novel mixed-mode weak cation-exchange sorbent (PS-DVB-WCX-II) was prepared by the modification of polystyrene-divinylbenzene with mercaptosuccinic acid for the selective extraction of illicit drugs in environmental water. The PS-DVB-WCX-II was synthesized through the Friedel-Crafts acylation reaction on the surface of polystyrene-divinylbenzene, followed by nucleophilic substitution reaction and thiol-ene click reaction. The sorbent can selectively absorb illicit drugs through the reverse-phase interactions provided by benzene ring on the polymer backbone and the ion-exchange interactions provided by functional group (-COOH). As compared with the extraction performance of three commercial SPE cartridges, it was found that the prepared sorbent had better adsorption performance with the recovery values between 84.1% and 106.0% for the selected 11 illicit drugs under the optimized SPE conditions. Illicit drugs in environmental water were extracted by the sorbent, prior to the detection of UHPLC-MS/MS. Two quantitative methods were established respectively for the detection of 11 illicit drugs in different matrices of river water and wastewater. Both methods had good determination coefficient (r2>0.992) in the range of 0.5-50 ng/L, 2.5-250 ng/L, 5-500 ng/L, and low limits of detection (S/N = 3) of 0.17-1.67 ng/L. In the real wastewater samples, the concentration of morphine was 18.3-126.3 ng/L, and the methamphetamine was 12.7-27.4 ng/L. Meanwhile, PS-DVB-WCX-II was compared with Oasis MCX and Oasis HLB in the detection of real wastewater samples. The results revealed that PS-DVB-WCX-II and Oasis MCX had better performance in absorbing methamphetamine than Oasis HLB, and PS-DVB-WCX-II had better ability to remove the matrix. The results suggested that the prepared weak cation-exchange sorbent had the potential in the application of illicit drug detection in environmental water.

Effects and mechanisms of natural alkaloids for prevention and treatment of osteoporosis.

Natural alkaloids are polycyclic, nitrogen-containing, and basic compounds obtained from plants. In this review, the advances in bioactive alkaloids with respect to their chemical structures, herbal sources, and effects for the prevention and treatment of osteoporosis are discussed. Anti-osteoporosis alkaloids are classified into six categories based on the chemical structure, namely, isoquinoline alkaloids, quinolizidine alkaloids, piperidine alkaloids, indole alkaloids, pyrrolizidine alkaloids and steroidal alkaloids. They promote mesenchymal stem cells differentiation, improve osteoblast proliferation, stimulate osteoblast autophagy and suppress osteoclast formation. These natural alkaloids can regulate multiple signaling pathways, including interrupting the tumor necrosis factor receptor associated factor 6- receptor activator of nuclear factor kappa B interaction, inhibiting the nuclear factor kappa B pathway in osteoclasts, activating the p38 mitogen-activated protein kinases pathway in osteoblasts, and triggering the wingless and int-1 pathway in mesenchymal stem cells. This review provides evidence and support for novel drug and clinical treatment of osteoporosis using natural alkaloids.

Novel pentadecenyl tetrazole enhances susceptibility of methicillin-resistant Staphylococcus aureus biofilms to gentamicin.

One method that bacteria employ to reduce their susceptibility to antibiotics is the formation of biofilms. We developed a robust 6-well plate biofilm assay to evaluate early-stage discovery compounds against methicillin-resistant Staphylococcus aureus (MRSA). Tissue culture-treated 6-well plates were selected for this assay because they facilitate the adherence of MRSA and enable accurate determination of the number of CFU in each well. The MRSA biofilms formed in this assay exhibit increased tolerances to clinically used antibiotics. Using this biofilm assay, we identified a novel potentiator of gentamicin against MRSA biofilms. The combination of gentamicin and pentadecenyl tetrazole is superior to clinically used MRSA antibiotics against these MRSA biofilms. This novel combination also exhibits synergistic effects on MRSA planktonic cells. This plant-derived compound reveals promise for its effectiveness and warrants further lead optimization as an antibiotic and aminoglycoside potentiator.