Quantitation of Atmospheric Suspended Polystyrene Nanoplastics by Active Sampling Prior to Pyrolysis-Gas Chromatography-Mass Spectrometry.

Plastic has been demonstrated to release nanoplastics (NPs) into the atmosphere under sunlight irradiation, posing a continuous health risk to the respiratory system. However, due to lack of reliable quantification methods, the occurrence and distribution of NPs in the atmosphere remain unclear. Polystyrene (PS) micro- and nanoplastics (MNPs) represent a crucial component of atmospheric MNPs. In this study, we proposed a simple and robust method for determining the concentration of atmospheric PS NPs using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Following active sampling, the filter membrane is directly ground and introduced into the Py-GC/MS system to quantify PS NPs. The proposed method demonstrates excellent reproducibility and high sensitivity, with a detection limit as low as down to 15 pg/m3 for PS NPs. By using this method, the occurrence of PS NPs in both indoor and outdoor atmospheres has been confirmed. Furthermore, the results showed that the abundance of outdoor PS NPs was significantly higher than that of indoor samples, and there was no significant difference in NP vertical distribution within a height of 28.6 m. This method can be applied for the routine monitoring of atmospheric PS NPs and for evaluating their risk to human health.

Hybrid of Fe3C@N, S co-doped carbon nanotubes coated porous carbon derived from metal organic frameworks as an efficient catalyst towards oxygen reduction.

High cost, low reserves and poor stability of the Pt-based catalysts have hindered their large-scale applications. To solve these problems, we develop an efficient method to fabricate a hybrid of Fe3C@N, S co-doped carbon nanotubes coated porous carbon as a superior catalyst towards ORR. The resulted Fe-N-S/C sample exhibits excellent performance in alkaline solution, with a half-wave potential of 0.89 V, which is 30 mV higher than that of commercial Pt/C. The electron transfer number is 3.9 at 0.4 V, indicating a direct four-electron (4e-) pathway towards ORR, and the kinetic current density Jk is 7.96 mA cm-2 at 0.88 V. After 5000 repeated potential cycling test, only 4 mV of down-shift in its half-wave potential was detected, which manifested the remarkable stability of Fe-N-S/C. The electrochemical performance is attributed to the ordered porous structure, high content of active N-species and the synergistic effect between Fe3C group and S dopants.

A Comparative Study of Albumin-Bilirubin Score with Child-Pugh Score, Model for End-Stage Liver Disease Score and Indocyanine Green R15 in Predicting Posthepatectomy Liver Failure for Hepatocellular Carcinoma Patients.

BACKGROUND: The albumin-bilirubin (ALBI) grade is a newly proposed model for assessing the hepatic function. This study aimed to compare the value of the ALBI score with Child-Pugh score, model for end-stage liver disease (MELD) score and indocyanine green (ICG) R15 in predicting posthepatectomy liver failure (PHLF). METHODS: Patients undergoing curative resection for hepatocellular carcinoma (HCC) between January 2014 and June 2017 were enrolled. The values of the Child-Pugh score, MELD score, ICG R15 and ALBI score in predicting PHLF were evaluated. RESULTS: A total of 473 HCC patients were enrolled. The ALBI score was identified as an independent predictor of PHLF. The AUCs for the Child-Pugh score, MELD score, ICG R15 and ALBI score in predicting PHLF were 0.665, 0.649, 0.668, and 0.745 respectively. Multivariable analyses revealed that the ALBI score was an independent predictor of PHLF regardless of the hepatectomy subgroups, but the Child-Pugh score and MELD score were not significant predictors of PHLF both in major and minor hepatectomy subgroups, and ICG R15 was only a significant predictor of PHLF in minor hepatectomy subgroup. CONCLUSION: The ALBI score showed superior predictive value of PHLF over Child-Pugh score, MELD score and ICG R15. We propose to use the ALBI score to evaluate surgical risk for HCC patients undergoing hepatic resection.

A General Strategy Assisted with Dual Reductants and Dual Protecting Agents for Preparing Pt-Based Alloys with High-Index Facets and Excellent Electrocatalytic Performance.

Synthesizing noble metallic nanoparticles (NPs) enclosed by high-index facets (HIFs) is challenged as it involves the tuning of growth kinetics, the selective adsorption of certain chemical species, and the epitaxial growth from HIF enclosed seeds. Herein, a simple and general strategy is reported by using dual reduction agents and dual capping agents to prepare Pt-based alloy NPs with HIFs, in which both glycine and poly(vinylpyrrolidone) serve as the reductants and capping agents. Due to the facilely tunable growth/nucleation rates and protecting abilities of the reductants and capping agents, Pt concave nanocube (CNC), binary Pt-Ni CNC, ternary Pt-Mn-Cu CNC, and Pt-Mn-Cu ramiform polyhedron alloy NPs terminated by HIFs as well as other NPs with well-defined morphologies such as Pt-Mn-Cu nanocube and Pt-Mn-Cu nanoflower are obtained with this approach. Owing to the high density of low-coordinated Pt sites (HIF structure) and the unique electronic effect of Pt-Mn-Cu ternary alloys, the as-prepared Pt-Mn-Cu NPs show enhanced catalytic activity toward methanol and formic acid electro-oxidation reactions with excellent stability. This work provides a promising methodology for designing and fabricating Pt-based alloy NPs as efficient fuel cell catalyst.

Preconcentration of nickel and cadmium by TiO2 nanotubes as solid-phase extraction adsorbents coupled with flame atomic absorption spectrometry.

TiO(2) nanotubes, a new nanomaterial, are often used in the photocatalysis. Due to its relatively large specific surface areas it should have a higher enrichment capacity. However, very few applications in the enrichment of pollutants were found. This paper described a new procedure to investigate the trapping power of TiO(2) nanotubes with cadmium and nickel in water samples as the model analytes and flame atomic absorption spectrometry for the analysis. The possible parameters influencing the enrichment were optimized. Under the optimal SPE conditions, the method detection limits and precisions (R.S.D., n=6) were 0.25 ngmL(-1) and 2.2% for cadmium, 1 ngmL(-1) and 2.6% for nickel, respectively. The established method has been successfully applied to analyze four realworld water samples, and satisfactory results were obtained. The spiked recoveries were in the range of 90.2-99.2% for them. All these indicated that TiO(2) nanotubes had great potential in environmental field.

Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry.

In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes (MWCNTs) and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry. The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing. Parameters influencing the recoveries of target analytes were optimized. Under optimal conditions, the target analyte exhibited a good linearity (R2=0.9992) over the concentration range 0.5-50 ng/ml. The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively. The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%. All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.

Rapid determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration.

A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol concentration had an excellent linear relationship over the range of 4.82 x 10(-6)-9.65 x 10(-3) mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.

Identification and analysis of YELLOW protein family genes in the silkworm, Bombyx mori.

BACKGROUND: The major royal jelly proteins/yellow (MRJP/YELLOW) family possesses several physiological and chemical functions in the development of Apis mellifera and Drosophila melanogaster. Each protein of the family has a conserved domain named MRJP. However, there is no report of MRJP/YELLOW family proteins in the Lepidoptera. RESULTS: Using the YELLOW protein sequence in Drosophila melanogaster to BLAST silkworm EST database, we found a gene family composed of seven members with a conserved MRJP domain each and named it YELLOW protein family of Bombyx mori. We completed the cDNA sequences with RACE method. The protein of each member possesses a MRJP domain and a putative cleavable signal peptide consisting of a hydrophobic sequence. In view of genetic evolution, the whole Bm YELLOW protein family composes a monophyletic group, which is distinctly separate from Drosophila melanogaster and Apis mellifera. We then showed the tissue expression profiles of Bm YELLOW protein family genes by RT-PCR. CONCLUSION: A Bombyx mori YELLOW protein family is found to be composed of at least seven members. The low homogeneity and unique pattern of gene expression by each member among the family ensure us to prophesy that the members of Bm YELLOW protein family would play some important physiological functions in silkworm development.

The scaleless wings mutant in Bombyx mori is associated with a lack of scale precursor cell differentiation followed by excessive apoptosis.

The scaleless wings mutant in Bombyx mori (scaleless, sl) was previously reported morphologically. In the present study, we give data to clarify the mechanism of the mutation at the developmental level. Programmed cell death participates in the wing scale development during early pupal stage, and there are significant differences between that of sl and the wild type (WT) at each phase. Well-differentiated scale precursor cells do not form in sl when they have formed in WT. The peak of Caspase-3/7 activity in sl occurs 1 day later than and ten times as much as that in WT. Apoptotic bodies and DNA ladder studies also show that there is excessive apoptosis in sl early pupal wing. In addition, we have studied Bm-ASH1, an achaete-scute homolog in B.mori, which is thought to play a key role during the development of wing scales, and have found that the gene structure and expression levels of Bm-ASH1 in sl and WT are identical. All the data indicate that the wing scale precursor differentiation mechanism is abnormal in sl, which causes failing determination of scale cells and the downstream symptom of excessive apoptosis. But some of the elements to the scale differentiation circuit, such as Bm-ASH1, still operate in sl.

Headspace liquid-phase microextraction using ionic liquid as extractant for the preconcentration of dichlorodiphenyltrichloroethane and its metabolites at trace levels in water samples.

A novel technique, high temperature headspace liquid-phase microextraction (HS-LPME) with room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) as extractant, was developed for the analysis of dichlorodiphenyltrichloroethane (p,p'-DDT and o,p'-DDT) and its metabolites including 4,4'-dichlorodiphenyldichloroethylene (p,p'-DDE) and 4,4'-dichlorodiphenyldichloroethane (p,p'-DDD) in water samples by high performance liquid chromatography with ultraviolet detection. The parameters such as salt content, sample pH and temperature, stirring rate, extraction time, microdrop volume, and sample volume, were found to have significant influence on the HS-LPME. The conditions optimized for extraction of target compounds were as follows: 35% NaCl (w/v), neutral pH condition, 70 degrees C, 800 rpm, 30 min, 10 microL [C4MIM][PF6], and 25 mL sample solutions. Under the optimized conditions, the linear range, detection limit (S/N=3), and precision (R.S.D., n=6) were 0.3-30 microg L(-1), 0.07 microg L(-1), and 8.0% for p,p'-DDD, 0.3-30 microg L(-1), 0.08 microg L(-1), and 7.1% for p,p'-DDT, 0.3-30 microg L(-1), 0.08 microg L(-1), and 7.2% for o,p'-DDT, and 0.2-30 microg L(-1), 0.05 microg L(-1), and 6.8% for p,p'-DDE, respectively. Water samples including tap water, well water, snow water, reservoir water, and wastewater were analyzed by the proposed procedure and the recoveries at 5 microg L(-1) spiked level were in the range of 86.8-102.6%.

Use of ionic liquids for liquid-phase microextraction of polycyclic aromatic hydrocarbons.

This paper demonstrates, for the first time, that ionic liquids (IL) such as 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) are excellent extraction solvents in liquid-phase microextraction (LPME). The unique properties of nonvolatility and adequate viscosity allow IL to be conveniently adopted as extraction solvents in both direct-immersion and headspace LPME. Model compounds, polycyclic aromatic hydrocarbons (PAHs), are conveniently and rapidly enriched in a 3-microL drop of [C(8)MIM][PF(6)] suspended on the tip of a microsyringe followed by liquid chromatographic determination. Compared to 1-octanol, a larger volume drop of [C(8)MIM][PF(6)] can be formed and survive for a longer extraction time; therefore, a much higher enrichment factor for PAHs can be reached. For low-volatility PAHs, direct-immersion LPME provides higher enrichment factors than that of headspace LPME. However, the enrichment factor obtained by headspace LPME was almost 3-fold of that by direct-immersion LPME in a 30-min extraction of the most volatile PAH, naphthalene. For 30-min direction-immersion LPME of EPA priority PAHs, the enrichment factor, correlation coefficient (R(2)), and reproducibility (RSD, n = 5) were in the range of 42-166, 0.9169-0.9976, and 2.8-12%, respectively. Considering that IL can be easily prepared from relatively inexpensive materials and tuned by combination of different anions and cations for task-specific extraction of analytes from various solvent media, this proposed method should have great potentiality in sample preparation. Furthermore, the nonvolatility of IL makes it potentially useful for headspace LPME of volatile analytes.

Evaluation of an on-line coupled continuous flow liquid membrane extraction and precolumn system as trace enrichment technique by liquid chromatographic determination of bisphenol A.

An on-line coupled continuous flow liquid membrane extraction (CFLME) and C(18) precolumn system was developed for sample preconcentration in liquid chromatography determination. After preconcentration by CFLME, which is based on the combination of continuous flow liquid-liquid extraction and supported liquid membrane, bisphenol A (BPA) was enriched in 960 microl of 1 mol l(-1) NaOH used as acceptor. This acceptor was on-line neutralized and transported onto the C(18) precolumn where analytes were absorbed and focused. Then the focused analytes were injected onto a C(18) analytical column for separation and detected at 220 nm with a diode array detector. CFLME related parameters such as flow rates, pH of donor and acceptor, and enrichment time were optimized. The proposed method presents a detection limit of 0.03 microg l(-1) (S/N=3) when 60 ml samples was enriched with an enrichment time of 30 min. Compared with C(18) based column-switching procedure, this proposed procedure presents similar sample throughput and lower detection limits. The proposed method was successfully applied to determine BPA in tap water, river water, and municipal sewage effluent samples.