Performance and mechanism of Cr(VI) removal by zero-valent iron loaded onto expanded graphite.

Zero-valent iron (ZVI) was loaded on expanded graphite (EG) to produce a composite material (EG-ZVI) for efficient removal of hexavalent chromium (Cr(VI)). EG and EG-ZVI were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. EG-ZVI had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr(VI) removal performance. The results showed that the Cr(VI) removal rate was 98.80% for EG-ZVI, which was higher than that for both EG (10.00%) and ZVI (29.80%). Furthermore, the removal rate of Cr(VI) by EG-ZVI showed little dependence on solution pH within a pH range of 1-9. Even at pH11, a Cr(VI) removal rate of 62.44% was obtained after reaction for 1hr. EG-ZVI could enhance the removal of Cr(VI) via chemical reduction and physical adsorption, respectively. X-ray photoelectron spectroscopy (XPS) was used to analyze the mechanisms of Cr(VI) removal, which indicated that the ZVI loaded on the surface was oxidized, and the removed Cr(VI) was immobilized via the formation of Cr(III) hydroxide and Cr(III)-Fe(III) hydroxide/oxyhydroxide on the surface of EG-ZVI.

Lung computed tomography image segmentation based on U-Net network fused with dilated convolution.

PURPOSE: In order to solve the problem of accurate and effective segmentation of the patient's lung computed tomography (CT) images, so as to improve the efficiency of treating lung cancer. METHOD: We propose a U-Net network (DC-U-Net) fused with dilated convolution, and compare the results of segmented lung CT with DC-U-Net, Otsu and region growth. We use Intersection over Union (IOU), Dice coefficient, Precision and Recall to evaluate the performance of the three algorithms. RESULTS: Compared with the common segmentation algorithm Otsu and region growing, the segmented image of DC-U-Net is closer to the Ground truth. The IOU of DC-U-Net is 0.9627, and the Dice coefficient is 0.9743, which is close to 1 and much higher than the other two algorithms. CONCLUSION: We propose that the model can directly segment the original image automatically, and the segmentation effect is good. This model speeds up the segmentation, simplifies the steps of medical image segmentation, and provides better segmentation for subsequent lung blood vessels, trachea and other tissues.

miR-526b-3p inhibits lung cancer cisplatin-resistance and metastasis by inhibiting STAT3-promoted PD-L1.

Chemotherapy remains the primary treatment of advanced solid cancer, including lung cancer. However, as first-line treatment, cisplatin-based therapy is restricted by the frequent development of drug resistance. Increasing data showed that the programmed cell death protein ligand 1 (PD-L1) plays a vital role in regulating cisplatin resistance. However, the underlying mechanisms are not fully understood. We found that miR-526b-3p expression declined while PD-L1 was elevated in cisplatin-resistant lung cancer compared to that in cisplatin-sensitive lung cancer by analyzing clinical samples. Significantly, miR-526b-3p was associated with response to cisplatin negatively. We further demonstrated that miR-526b-3p reversed cisplatin resistance, suppressed metastasis, and activated CD8+ T cells in a STAT3/PD-L1-dependent manner. Thus, our findings extended the knowledge of PD-L1-mediated cisplatin resistance of lung cancer. In addition, the introduction of miR-526b-3p provided a new clue to improve the anti-tumor effects of the combination of immunotherapy and chemotherapy.

Esophageal cancer detection based on classification of gastrointestinal CT images using improved Faster RCNN.

PURPOSE: Esophageal cancer is a common malignant tumor in life, which seriously affects human health. In order to reduce the work intensity of doctors and improve detection accuracy, we proposed esophageal cancer detection using deep learning. The characteristics of deep learning: association and structure, activity and experience, essence and variation, migration and application, value and evaluation. METHOD: The improved Faster RCNN esophageal cancer detection in this paper introduces the online hard example mining (OHEM) mechanism into the system, and the experiment used 1520 gastrointestinal CT images from 421 patients. Then, we compare the overall performance of Inception-v2, Faster RCNN, and improved Faster RCNN through F-1 measure, mean average precision (mAP), and detection time. RESULTS: The experiment shows that the overall performance of the improved Faster RCNN is higher than the other two networks. The F-1 measure of our method reaches 95.71%, the mAP reaches 92.15%, and the detection time per CT is only 5.3s. CONCLUSION: Through comparative analysis on the esophageal cancer image data set, the experimental results show that the introduction of online hard example mining mechanism in the Faster RCNN algorithm can improve the detection accuracy to a certain extent.

Characterization of PAHs contamination in soils from metropolitan region of Northern China.

The present study characterized the distribution, sources as well as carcinogenic potency of PAHs in surface soil from metropolitan region of northern China. The total PAHs in topsoil ranged from 322.6 to 23244.7 microg kg(-1). The mean and median concentrations of 16 PAHs were 1040.8 and 626.7 microg kg(-1), respectively. Source analysis revealed that pyrogenic sources played a major role at the locations and pyrogenic PAHs were mainly from incomplete combustion of coal, biomass and petroleum. The calculated mean BaP-equivalent values for individual carcinogenic PAHs were 148.4 microg kg(-1).

Concentrations and bioaccessibility of polycyclic aromatic hydrocarbons in wastewater-irrigated soil using in vitro gastrointestinal test.

BACKGROUND, AIM, AND SCOPE: Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. MATERIALS AND METHODS: Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear regression model was used to assess the relationship between total PAH concentrations in soils and soil organic carbon (SOC). RESULTS: A wide range of total PAH concentrations ranging from 1,304 to 3,369 mug kg(-1) in soils collected from different wastewater-irrigated sites in Tianjin, while ranging from 2,687 to 4,916 mug kg(-1) in soils collected from different wastewater-irrigated sites in Beijing, was detected. In general, total PAH concentrations in soils from Beijing sites were significantly higher than those from Tianjin sites, indicating a dominant contribution from both pyrogenic and petrogenic sources. Results indicated that the oral bioaccessibility of PAHs in small intestinal was significantly higher (from P < 0.05 to P < 0.001) than gastric condition. Similarly, the oral bioaccessibility of PAHs in contaminated sites was significantly higher (from P < or = 0.05 to P < 0.001) than in reference sites. Individual PAH ratios (three to six rings), a more accurate and reliable estimation about the emission sources, were used to distinguish the natural and anthropogenic PAH inputs in the soils. Results indicated that PAHs were both pyrogenic and petrogenic in nature. DISCUSSION: The identification of PAH sources and importance of in vitro test for PAH bioaccessibility were emphasized in this study. The oral bioaccessibility of individual PAHs in soils generally decreased with increasing ring numbers of PAHs in both the gastric and small intestinal conditions. However, the ratio of bioaccessibility of individual PAHs in gastric conditions to that in the small intestinal condition generally increased with increasing ring numbers, indicating the relatively pronounced effect of bile extract on improving the bioaccessibility of PAHs with relatively high ring numbers characterized by their high K ( ow ) values. Similarly, total PAH concentrations in soils were strongly correlated with SOC, indicating that SOC was the key factor determining the retention of PAHs in soils. CONCLUSIONS: Soils were contaminated with PAHs due to long-term wastewater irrigation. PAHs with two to six rings showed high concentrations with a significant increase over reference soils. Based on the molecular indices, it was suggested that PAHs in soils had both pyrogenic and petrogenic sources. It was also concluded that the oral bioaccessibility of total PAHs in the small intestinal condition was significantly higher than that in the gastric condition. Furthermore, the bioaccessibility of individual PAHs in soils generally decreased with the increasing ring numbers in both the gastric and small intestinal conditions. RECOMMENDATIONS AND PERSPECTIVES: It is suggested that more care should be given while establishing reliable soil criteria for PAHs, especially concerning the health of children who may ingest a considerable amount of PAH-contaminated soil via outdoor hand-to-mouth activities.

Effects of exposure time and co-existing organic compounds on uptake of atrazine from nutrient solution by rice seedlings (Oryza sativa L.).

Root uptake of atrazine (ATR) by rice seedlings (Oryza sativa L.) from nutrient solution was investigated with exposure periods of 48, 96, and 240h. A similar ATR uptake was carried out with two co-existing organic compounds (o-chlorophenol (CP) and 2,4-dichlorophenol (DCP)) with 48h exposure. In contact with the seedlings, the ATR level in nutrient solution decreased sharply during the early exposure and then reached relatively steady levels after 48h. It was observed that the ATR levels within whole seedlings approached the estimated equilibrium partition limits in about 48h, according to the partition-limited model utilizing the measured plant water and organic matter contents and the ATR partition coefficients with whole seedlings. However, when roots and shoots were consisted separately, the detected ATR levels in roots were lower than estimated equilibrium limit while the levels in shoots exceeded the equilibrium limit. The data with roots suggested the occurrence of rapid ATR degradation in roots. The results with shoots are intrinsically consistent with the suggested complex formation of ATR with free metal ions in shoots. The ATR levels in roots and shoots varied to a moderate extent when the seedlings were exposed to different levels of ATR-CP-DCP mixtures. The variation results presumably from the interference of coexisting CP and DCP and the phytotoxicity of the mixed chemicals.

Wheat phytotoxicity from arsenic and cadmium separately and together in solution culture and in a calcareous soil.

The toxicity of two toxic elements, arsenic (As) and cadmium (Cd) (individually or in combination) on root elongation of wheat seedlings (Triticum aestivum, L.) were investigated both in hydroponics and in soils freshly spiked with the toxic elements. Median effective concentration (EC(50)) and non-observed effect concentration (NOEC) were used to investigate the toxic thresholds and potencies of the two elements. The EC(50) for As was 0.97 microM in hydroponics and 196 mgkg(-1) in soil, and 4.32 microM and 449 mgkg(-1) for Cd, respectively. Toxic unit (TU) and additive index (AI) concepts were introduced to determine the combined outcomes, and different behaviors were obtained: synergism in solution culture (EC(50 mix)=0.36 TU(mix) and AI: 1.76) and antagonism in soil experiments (EC(50 mix)=1.49 TU(mix) and AI: -0.33). Furthermore, the data of soil bioavailable As and Cd cannot explain the discrepancy between the results derived from soil and hydroponics experiments.

Oxidative stress and DNA damages induced by cadmium accumulation.

Experimental evidence shows that cadmium (Cd) could induce oxidative stress and then causes DNA damage in animal cells, however, whether such effect exists in plants is still unclear. In the present study, Vicia faba plants was exposed to 5 and 10 mg/L Cd for 4 d to investigate the distribution of Cd in plant, the metal effects on the cell lipids, antioxidative enzymes and DNA damages in leaves. Cd induced an increase in Cd concentrations in plants. An enhanced level of lipid peroxidation in leaves and an enhanced concentration of H2O2 in root tissues suggested that Cd caused oxidative stress in Vicia faba. Compared with control, Cd-induced enhancement in superoxide dismutase activity was more significant at 5 mg/L than at 10 mg/L in leaves, by contrast, catalase and peroxidase activities were significantly suppressed by Cd addition. DNA damage was detected by neutral/neutral, alkaline/neutral and alkaline/alkaline Comet assay. Increased levels of DNA damages induced by Cd occurred with reference to oxidative stress in leaves, therefore, oxidative stress induced by Cd accumulation in plants contributed to DNA damages and was likely an important mechanism of Cd-phytotoxicity in Vicia faba plants.

Arbuscular mycorrhizal fungi can alleviate the adverse effects of chlorothalonil on Oryza sativa L.

A glasshouse pot experiment was conducted to investigate the effect of the fungicide chlorothalonil on the growth of upland rice, in the absence or presence of the arbuscular mycorrhizal fungus (AMF) Glomus mosseae (NM and GM treatments). The plants were grown with three concentrations of chlorothalonil (0, 50 and 100 mg kg(-1) soil). Mycorrhizal colonization decreased significantly with increasing chlorothalonil concentrations. Plant biomass decreases were smaller in GM plants than in non-mycorrhizal (NM) plants. Mycorrhizal dependency was the highest with 50 mg kg(-1) chlorothalonil. Chlorothalonil affected physiological processes in upland rice irrespective of inoculation. Chlorothalonil at 50 and 100 mg kg(-1) increased ascorbate peroxidase (APX) activity and soluble protein concentrations in shoots and roots of NM upland rice. However, values of APX, catalase (CAT) and peroxidase (POD) were reduced more in GM plants than in NM plants. These results showed that chlorothalonil induced oxidative stress in upland rice and it is needed to evaluate the side effects of chlorothalonil on rice and AMF.

Effects of Glomus mosseae on the toxicity of heavy metals to Vicia faba.

A glasshouse pot experiment was conducted to investigate effects of the arbuscular mycorrhizal fungus Glomus mosseae on the growth of Vicia faba and toxicity induced by heavy metals (HMs) (Cu, Zn, Pb and Cd) in a field soil contaminated by a mixture of these metals. There was also uninoculation treatment (NM) simultaneously. Mycorrhizal (GM) plants hav e significantlyincreased growth and tolerance to toxicity induced by heavy metals compared with NM plants. P uptake was significantly increased in GM plants. Mycorrhizal symbiosis reduced the transportation of HMs from root to shoot by immobilizing HMs in the mycorrhizal, shown by increasing the ratios of HMs from root to shoot. Oxidative stress, which can induce DNA damage, is an important mechanism of heavy metal toxicity. GM treatment decreased oxidative stress by intricating antioxidative systems such as peroxidases and non-enzymic systems including soluble protein. The DNA damage induced by heavy metals was detected using comet assay, which showed DNA damage in the plants was decreased by the GM treatment.

Interaction between cadmium and atrazine during uptake by rice seedlings (Oryza sativa L.).

The uptake of atrazine by rice seedlings (Oryza sativa L.) through plant roots from nutrient solution was investigated in the presence and absence of Cd2+ over an exposure period of four weeks. It was found that both atrazine and Cd2+ were toxic to rice seedlings. Both shoot and root biomasses decreased when the seedlings were exposed to increasing atrazine or Cd2+ concentrations in nutrient solutions. In the absence of Cd2+, a linear relationship was observed between atrazine concentrations in roots/shoots and in external solution, and more atrazine is concentrated in roots than in shoots. When atrazine and Cd2+ concentrations in solution were maintained at mole ratio of 1:1, the accumulation of atrazine by seedlings was less and the seedling biomass was greater than found with other ratios, such as 1:2 or 2:1. Therefore, the formation of the complex between atrazine and Cd2+ reduced the individual toxicities. Analyses of data with the quasi-equilibrium partition model indicated that the atrazine concentrations in rice seedlings and external water were close to equilibrium. In the presence of Cd2+, however, the measured bioconcentration factor (BCF) of atrazine with roots and shoots were considerably greater. The latter findings resulted presumably from the atrazine-Cd2+ complex formation that led to a large apparent BCF.

Construction of 3,6-anhydrohexosides via intramolecular cyclization of triflates and its application to the synthesis of natural product isolated from leaves of Sauropus rostratus.

A novel synthetic approach to construct various 3,6-anhydrohexosides via an intramolecular cyclization of corresponding triflates is described. The nucleophilic attack from C3 p-methoxybenzylated hydroxyl to C6 trifluoromethanesulfonate on triflate structures triggered the cyclization reaction to provide 3,6-anhydrohexosides in excellent yields, making the strategy more efficient with respect to the reported protocols. By applying this methodology, a concise first total synthesis of natural product isolated from leaves of Sauropus rostratus was accomplished.

[Isolation and degradation characteristics of acetochlor-degrading strain A-3].

The strain A-3 which could use acetochlor as the sole nitrogen source was isolated from soils contaminated with acetochlor and the sludge of pesticide factory by enrichment culture. The strain was identified as Ensifer adhaerens according to the results of morphology, physiology,and the phylogenetical analyses of 16S rRNA sequence. It was observed that the degradation rate of acetochlor by strain A-3 was 33.6% after 10 days culture at the concentration of 10 mg/L. The composition of the culture could affect the growth of A-3 and the degradation of acetochlor. The growth and degradation ability of strain A-3 were different with the different carbon sources. The strain had the strangest growth capability with the D600 value of 0.55, but the degradation rate was only 9.4% when using sucrose as carbon source. However, the strain A-3 had the highest degradation rate up to 29.2%, although the D600 value was only 0.3 when using glucose as carbon source. When the NaCl concentration was 0.5%, the strain A-3 grew best and had the highest degradation rate of 35%, but when the NaCl concentration was higher than 7%, the growth of A-3 was inhibited and the degradation rate was reduced to 2.6%. The results showed that the strain A-3 could degrade acetochlor effectively and the growth and degradation process was affected by environmental media, and the degradation of acetochlor could be controlled by changing the composition of the culture.

[Survey of arsenic concentrations in Chinese herbal medicines (CHMs) and preliminary risk assessment of As in CHMs on human health].

Characteristics and concentrations of As in Chinese Herbal Medicines (CHMs) from Hebei province (including samples collected from fields and from medicine markets) were investigated, and the ADI (allowable daily intake) standard value from FAO/WHO was used for preliminary assessment of As risk on human health. The results showed that the average of As concentrations in different roots which were used as medicines, ranged from 0.14 mg/kg to 0.54 mg/kg,while for shoots which were used as medicines, average value of As concentrations in Dendranthema morifolium was 1.42 mg/kg, and the range in other species was from 0.09 mg/kg to 0.27 mg/kg. Based on Green Standards of Medicinal Plants and Preparations for Foreign Trade and Economy (2.0 mg/kg), the percentage of samples with As concentrations exceeding standard was 3.27% (n = 153) in roots and 9.09% (n = 44) in shoots,and 4.57% (n = 197) in total CHMs samples. As concentrations in CHMs from fields ranged from 0.03 mg/kg to 0.73 mg/kg,which were all lower than 2.0 mg/kg. However, As concentrations in CHMs from markets ranged from 0.05 mg/kg to 7.05 mg/kg, and the concentrations of As in 6.36% of samples exceeded the limited standard. Arsenic concentrations in samples from markets were significantly higher than those from fields (p < 0.05). As concentrations in Compositae were distributed widely from 0.08 mg/kg to 7.05 mg/kg,and the average at 0.87 mg/kg,while the average of As concentrations in other six families were between 0.21 mg/kg and 0.41 mg/kg, and As levels in 75% of samples for each family were below 0.5 mg/kg. Compared to Compositae samples, the CHMs from other families have higher security. ADI regulated by FAO/WHO was used to assess As risk in CHMs on human health in this study as well. As daily intake through CHMs from markets varied from 0.90 microg/d to 19.7 microg/d, and percentages of the daily intake of As in CHMs to ADI were in the range of 0.70% to 15.4%, which indicated that As in CHMs from markets had a potential risk on human health after intake.

[Arsenic speciation in edible plants: a review].

Arsenic (As) is a ubiquitous chemical element in environment, and the increasingly serious As pollution is highly concerned all over the world. China has been considered as one of the countries and regions with serious As pollution in the world by the World Health Organization (WHO). Recent studies indicated that food is one of the major contributors of As in human diets. Edible plants are essential in the diet structure in human life, which often contain high level of As. However, the total As in food can not exactly reflect the toxicity of As, while As speciation closely relates to the As bio-toxicity. Inorganic arsenic is verified as the carcinogen based on human epidemiological data. This paper reviewed the As species in edible plants, their bio-toxicity, and analytical methods.

[Identification of pyrene degrading strains and the degrading characteristics research].

Three bacterial strains J1, J2, J3 which could use pyrene as the sole carbon and energy sources were isolated from soils contaminated with polycyclic aromatic hydrocarbons (PAHs) by enrichment culture. The strains were identified as Pseudomonas aeruginosa, Flavobacterium mizutaii, Brevibacillus parabrevis according to the results of morphology, physiology and the phylogenetical analyses of 16S rDNA sequence. It was observed that the three strains could use pyrene at the concentrations of 50, 100, 200, 500, 1 000 mg/L and after 7 days culture the concentrations of microorganisms in the liquid medium were the highest. Under the treatment of 200 mg/L pyrene the degradation rate of pyrene by strain J1, J2, J3 was 53.04%, 65.03%, 51.02%. The three strains could grow and use pyrene at the culture medium pH 4 to pH 9 and the pH 7 was the best for the microbe growth and the degradation. Compare with the dichloromethane, N, N-dimethylformamide which could increase the solution of pyrene and enhance the degradation of pyrene was the better solvent in the pyrene degradation.

Arsenic accumulation by the aquatic fern Azolla: comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides.

This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methylated As species accounting for <5% of the total As. A. filiculoides had a higher proportion of arsenite than A. caroliniana. Both strains effluxed more arsenate than arsenite, and the amount of As efflux was proportional to the amount of As accumulation. The potential of growing Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated.

[Effects of arbuscular mycorrhizal fungi on the toxicity of chlorothalonil on upland rice (Oryzal sativa L.)].

Upland rice was selected as a host plant in a greenhouse-pot-culture experiment to investigate the effects of chlorothalonil and arbuscular mycorrhizal fungi (AMF) on the growth and oxidative damage under chlorothalonil stress. The plants were grown with three concentrations of chlorothalonil (0, 50 and 100 mg x kg(-1) soil). The results suggested that chlorothalonil inhibited the growth of upland rice and reduced dry weight of upland rice shoot from 2.5 g x pot(-1) to 1.0 g x pot(-1), and the root dry weight was reduced from 0.9 g x pot(-1) to 0.3 g x pot(-1). However, with AMF colonization the dry weight of upland rice was increased to 2.1 g x pot(-1). With 50 mg x kg(-1) chlorothalonil addition, the P uptake was reduced from 3200 microg x pot(-1) to 860 microg x pot(-1), but the AMF colonization could increased the P uptake to 1900 microg x pot(-1). Chlorothalonil induced oxidative stress indicating by the changes in activities of antioxidative enzyme and AMF colonization could alleviate the oxidative stress. These results showed that chlorothalonil induced oxidative stress and inhibited P uptake in upland rice and AMF could decrease the side effects of chlorothalonil by increasing P uptake and decreasing oxidative damages.

[Chemical fixation of metals in soil using bone char and assessment of the soil genotoxicity].

We evaluate the effects of soil in situ remediation by application of bone char as a soil amendment based on chemical and biological assessment. The application of bone char decreased the Pb in the in the water soluble (WS), exchangeable (EX), carbonate-bound (CAR) and Fe-Mn oxides-Bound (Fe-Mn) fraction but increased the Pb in organic-bound (ORG) fraction indicating the decreased bioavailability of Pb. The application of bone char decreased the Cd, Cu and Zn in water soluble, exchangeable, carbonate-bound fraction by increasing substantial amounts of heavy metals in the ORG fraction or Residual (RES) fraction. The soil genotoxicity was evaluated using plant comet assay of root tip cells of Allium cepa L. and the results indicated that bone char application reduced genotoxcity of heavy metals, decreasing the DNA damages in plants which was consistent with the changes of the chemical forms of Pb, Cd, Cu and Zn indicating the changes of the chemical forms of heavy metals may be one of the reasons for decreased soil genotoxicity.