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1.
J Nanosci Nanotechnol ; 20(1): 42-47, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31383138

RESUMO

There is an urgent need for in situ methods for detecting environmental pollution quickly and accurately. With the development of nanotechnology, a huge potential has been created for the design of highly sensitive sensors with low energy consumption and low costs. If a composite material constructed with carbon nanotubes is used as an electrode in contact with a contaminant, this material undergoes an oxidation-reduction reaction with the contaminant that allows the electrode to function as an electrochemical sensor. This study involved the application of multi-walled carbon nanotubes and modified working electrodes constructed with multi-walled carbon nanotube composites (Ag- and ZnO-multi-walled carbon nanotubes) as electrochemical sensors. These electrodes have good response speed and sensitivity at low concentrations, and they are reusable. To lower the price of these sensors, our goal was to maximize their sensitivity by using the low-cost multiwalled carbon nanotubes in conjunction with silver electroless plating of the multi-walled carbon nanotubes and multi-walled carbon nanotube composites.

2.
J Nanosci Nanotechnol ; 20(1): 643-646, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31383226

RESUMO

Recently, better understanding of nano-area is required for 5 nm or less technology node. In particular, the high contact resistance generated in a nano-area significantly degrades the device performance. In this study, we propose a direct contact resistance measurement method without a test structure by separate processes to improve the nano-area contact resistance. The nano-area contact resistance of Ti-Ti and Cu-Cu decreased from 6.46 MΩ to 1.08 MΩ and from 3.78 MΩ to 1.48 MΩ, respectively, when the metal line and native layer formed on the surface were removed. In addition, it is confirmed that the contact resistance decreased with an increase in bonding strength in the case of nano-area homo-metal contact. However, the contact resistance is affected by the tunneling effect and bond energy according to the distance between the first layers of atoms in the case of nano-area hetero-metal contact.

3.
J Pharm Biomed Anal ; 177: 112890, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31563756

RESUMO

Various immunoassay methods have been developed and used for the therapeutic drug monitoring (TDM) of cyclosporine (CsA). However, there is no report on the application of a time-resolved fluoroimmunoassay (TRFIA) in routine CsA TDM. The aim of this study was to evaluate the feasibility and validate the performance of a newly developed TRFIA method for CsA analysis in human whole blood. The TRFIA method was then compared with the method of chemiluminescent microparticle immunoassay (CMIA). The calibration range of the CsA-TRFIA method was 0-1000 ng/mL. The linear range and correlation coefficients were 30-1000 ng/mL and more than 0.990, respectively. The accuracy, precision, and inter-batch range were 90.0%-110.0%, less than 10%, and no more than 15%, respectively. The lowest limit of detection was less than 10 ng/mL. The linear regression equation was YCMIA = 0.961XTRFIA + 3.357, which showed that the measurements of CMIA and TRFIA were strongly correlated (r = 0.980). The results demonstrate that TRFIA is a precise and reproducible method for detecting the CsA concentration and can be used for routinely CsA TDM.

4.
J Nanosci Nanotechnol ; 20(4): 2628-2632, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492287

RESUMO

As a new topological insulator material, the ß-phase silver telluride (Ag2Te) nanowire is a narrow bandgap semiconductor, which is attractive for its excellent properties. In this study, Ag2Te nanowires were synthesized by one-step hydrothermalmethod. The nanowires showed good electrical properties with maximum drain-source voltage of 1.5 V, and the output current was up to 20 µA. The gate voltage has a significant effect on output current for the device. The Ag2Te nanowires will have more extensive and in-depth applications in the fields of optoelectronics and thermoelectricity.

5.
Artigo em Inglês | MEDLINE | ID: mdl-31717896

RESUMO

BACKGROUND: Urbanization will play a key role in ending the tuberculosis (TB) epidemic by 2030, but understanding the relationship between urbanization and the health threats posed by TB is incomplete. Therefore, this study aimed to explore the spatiotemporal distribution of TB at the township level during urbanization in the new urban area of Nanchang. METHODS: Seasonal-trend decomposition of time series analysis was used to explore the seasonal distribution and trend analysis. Global and local spatial autocorrelation statistics, and space-time scan statistics were performed to detect the spatiotemporal clusters of TB cases in the new urban area of Nanchang from 2010 to 2018. RESULTS: A total of 3245 TB cases were reported in the study area from 2010 to 2018. Of all the TB cases, 68% occurred in individuals older than 40 years old, 73.2% were male cases, and 56.6% were farmers. The primary seasonal peak was in late spring (April), and a smaller peak was in early autumn (September). The results of local indicators of spatial association showed that Jiaoqiao town and Changleng town might be "High-High" clusters. The most likely spatiotemporal cluster was located in the southwest of the study area in 2010, which included five towns, and then shifted to the northeast gradually. Across 2010 to 2018, nine spatiotemporal clusters were identified. The most likely cluster was located at the northeast of the study area. The center of this area was in Nanji town with a circle radius of 43.74 kilometers. CONCLUSIONS: The spatial clusters of TB incidence shifted to the rural region and the fringe of the new urban area of Nanchang. Targeted management strategies for urban migrants in the process of urbanization should be strengthened.

6.
Nanoscale ; 11(44): 21046-21060, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31686088

RESUMO

Nanozymes, which are functional nanomaterials with enzyme-like characteristics, have emerged as a highly-stable and low-cost alternative to natural enzymes. Apart from overcoming the limitations of natural enzymes (e.g., high cost, low stability or complex production), nanozymes are also equipped with the unique intrinsic properties of nanomaterials such as magnetism, luminescence or near infrared absorbance. Therefore, the development of nanozymes exhibiting additional functions to their catalytic activity has opened up new opportunities and applications within the biomedical field. To highlight the progress in the field, this review summarizes the novel applications of multifunctional nanozymes in various biomedical-related fields ranging from cancer diagnosis, cancer and antibacterial therapy to regenerative medicine. Future challenges and perspectives that may advance nanozyme research are also discussed at the end of the review.

7.
Analyst ; 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31697283

RESUMO

In this contribution, a one-pot method possessing the advantages of easy preparation, rapidness, efficiency and environmental friendliness has been developed for the first time for the facile synthesis of highly fluorescent actinian nickel-doped carbon nanoflowers (Ni-CNFWs) by using nickel(ii)acetylacetonate as a metal-carbon source. Various characterization studies indicate that metal nickel atoms have been successfully doped into carbon nanoflower frameworks with a weight percentage of 1.46 wt%. The Ni-CNFWs showed a "shell-core" actinian structure with ∼400 nm diameter and highly efficient fluorescence quenching ability in the presence of quercetin (Qut) due to the formed Meisenheimer complexes via the conjugation effect of p, π-electrons between Ni-CNFWs and Qut, which allowed the analysis of Qut in a very facile method. Under the optimal conditions, the decreased fluorescence of Ni-CNFWs showed a good linear relationship with the concentration of Qut ranging from 0.5 to 300.0 µM, and the limit of detection was 0.137 µM (3σ/k). Finally, the content of Qut in bovine serum was successfully detected with the novel on-off sensor, and the recoveries were 97.3-101.9%, which indicate that the constructed on-off sensor has a high selectivity and accuracy.

8.
Medicine (Baltimore) ; 98(44): e17685, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31689790

RESUMO

To compare imaging indicators and clinical effects of extreme lateral interbody fusion (XLIF) using allogenic bone, autologous bone marrow + allogenic bone, and rhBMP-2 + allogenic bone as bone graft materials in the treatment of degenerative lumbar diseases.This was a retrospective study of 93 patients with lumbar interbody fusion who underwent the extreme lateral approach from May 2016 to December 2017. According to the different bone graft materials, patients were divided into allogenic bone groups (group A, 31 cases), rhBMP-2 + allogenic bone (group B, 32 cases), and autologous bone marrow + allogenic bone (group C, 30 cases). There were no significant differences in gender, age, lesion segment, preoperative intervertebral space height, and preoperative Oswestry Dysfunction Index (ODI) and visual analogue scale (VAS) scores among the 3 groups (P > .05). Intervertebral space height, bone graft fusion rate, and ODI and VAS scores were compared immediately after surgery, and at 3, 6, and 12 months after surgery.All groups were followed up for 12 months. The intervertebral space height was significantly higher in the 3 groups immediately after surgery and at 3, 6, and 12 months after surgery, in comparison to before surgery (P < .05). There was no significant difference in the intervertebral space height among the 3 groups immediately after surgery and at 3, 6, and 12 months after surgery (P > .05). The fusion rate of group B and C was higher than that of groups A at 3, 6, and 12 months after surgery (P < .05). In the 3 groups, the VAS and ODI scores at 3, 6, and 12 months after surgery were significantly improved compared with the preoperative scores (P < .05). The VAS and ODI scores in groups B and C were significantly higher than those in group A (P < .05), but there was no significant difference between groups B and C (P > .05).The rhBMP-2 + allograft bone combination had good clinical effects and high fusion rate in XLIF.

9.
J Hazard Mater ; : 121570, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31753669

RESUMO

Hierarchical and heterogeneous CuO/NiO nanowall arrays were in situ grown on ceramic tubes via a facile template-free hydrothermal route, and then were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption techniques. The resultant composites exhibit network-like CuO/NiO array structures constructed by interconnected porous nanosheets, in which the decoration of CuO nanoparticles in NiO nanowall arrays was confirmed by XRD, XPS and TEM analyses. The 2.84 at % CuO decorated NiO sensor exhibits excellent sensing properties at 133 °C. The response to 5 ppm H2S attains 36.9, which increases as high as 5.6 times compared to the NiO one. The detection limit to H2S is further decreased from 1 ppb for the pure NiO sensor to 0.5 ppb. The CuO/NiO sensor shows a wide linear range from 50 to 1000 ppb, good repeatability, selectivity and long-term stability, which is expected to be a candidate for ppb-level H2S detection in real and complex environment of industrial production. Furthermore, the dominant H2S sensing mechanism is discussed from the view of the homo- and hierarchical architecture of the CuO/NiO arrays as well as the chemical and electronic sensitization effects of CuO decoration.

10.
World Neurosurg ; 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31759151

RESUMO

The authors reported a case of a 33-year-old female sufferred from the combination of primary gliosarcoma and arteriovenous malformation (AVM) as the first clinical presentation of intracranial hemorrhage. Subsequently, gene examination rarely found BRAF V600E mutation in the surgical specimen. The lesion was not completely identified with magnetic resonance imaging(MRI) and digital subtraction angiography (DSA). This case illustrates the occult and unusual feature of gliosarcoma. The pathogenesis of such coexistence might be related to underlying genetic alterations.

11.
Biomed Pharmacother ; 121: 109622, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31707340

RESUMO

BACKGROUND: Previous study has demonstrated that long noncoding RNA cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1) was abnormally expressed in diabetic nephropathy (DN). However, the underlying mechanism that allows CDKN2B-AS1 in the progression of DN remains to be further elucidated. METHODS: Peripheral blood cells of 24 diabetes patients with DN and 20 without DN were collected. Human glomerular mesangial cells (HGMC) were cultured in high glucose or low glucose medium. The expression levels of CDKN2B-AS1, microRNA (miR)-424-5p and high mobility group AT hook 2 (HMGA2) were detected by quantitative real-time polymerase chain reaction or western blot. The target association between miR-424-5p and CDKN2B-AS1 or HMGA2 was confirmed by dual-luciferase reporter and RNA immunoprecipitation assays. Cell proliferation, extracellular matrix (ECM) accumulation and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and western blot, respectively. RESULTS: CDKN2B-AS1 expression was up-regulated and miR-424-5p level was down-regulated in peripheral blood of DN patients and high glucose-treated HGMC cells. CDKN2B-AS1 was validated as a sponge of miR-424-5p. Silence of CDKN2B-AS1 repressed proliferation and ECM accumulation by increasing miR-424-5p. HMGA2 was a target of miR-424-5p and miR-424-5p overexpression inhibited proliferation, ECM accumulation and PI3K/AKT pathway by targeting HMGA2. Moreover, knockdown of CDKN2B-AS1 inhibited HMGA2 expression and PI3K/AKT pathway by increasing miR-424-5p. CONCLUSION: Knockdown of CDKN2B-AS1 suppressed proliferation, ECM accumulation and PI3K/AKT signaling by increasing miR-424-5p and decreasing HMGA2 in high glucose-treated HMGC cells.

12.
Sensors (Basel) ; 19(22)2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31752392

RESUMO

In the application of the wireless sensor and robot networks (WSRNs), there is an urgent need to accommodate flexible surveillance tasks in intricate surveillance scenarios. On the condition of flexible surveillance missions and demands, event coverage holes occur in the networks. The conventional network repair methods based on the geometric graph theory such as Voronoi diagram method are unable to meet the conditions of flexible surveillance tasks and severe multi-restraint scenarios. Mobile robots show obvious advantages in terms of adaptation capacity and mobility in hazardous and severe scenarios. First, we propose an event coverage hole healing model for multi-constrained scenarios. Then, we propose a joint event coverage hole repair algorithm (JECHR) on the basis of global repair and local repair to apply mobile robots to heal event coverage holes in WSRNs. Different from conventional healing methods, the proposed algorithm can heal event coverage holes efficaciously which are resulted from changing surveillance demands and scenarios. The JECHR algorithm can provide an optimal repair method, which is able to adapt different kinds of severe multi-constrained circumstances. Finally, a large number of repair simulation experiments verify the performance of the JECHR algorithm which can be adapted to a variety of intricate surveillance tasks and application scenarios.

13.
Sci Rep ; 9(1): 16653, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31723149

RESUMO

This study provides unique insights into the properties of iron (Fe) in the marine atmosphere over the late summertime Arctic Ocean. Atmospheric deposition of aerosols can deliver Fe, a limiting micronutrient, to the remote ocean. Aerosol particle size influences aerosol Fe fractional solubility and air-to-sea deposition rate. Size-segregated aerosols were collected during the 2015 US GEOTRACES cruise in the Arctic Ocean. Results show that aerosol Fe had a single-mode size distribution, peaking at 4.4 µm in diameter, suggesting regional dust sources of Fe around the Arctic Ocean. Estimated dry deposition rates of aerosol Fe decreased from 6.1 µmol m-2 yr-1 in the areas of ~56°N-80°N to 0.73 µmol m-2 yr-1 in the areas north of 80°N. Aerosol Fe solubility was higher in fine particles (<1 µm) which were observed mainly in the region north of 80°N and coincided with relatively high concentrations of certain organic aerosols, suggesting interactions between aerosol Fe and organic ligands in the high-latitude Arctic atmosphere. The average molar ratio of Fe to titanium (Ti) was 2.4, substantially lower than the typical crustal ratio of 10. We speculate that dust sources around the Arctic Ocean may have been altered because of climate warming.

14.
Arch Toxicol ; 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31677073

RESUMO

The occurrence of idiosyncratic drug-induced liver injury (IDILI) is a leading cause of post-marketing safety warnings and withdrawals of drugs. Carbamazepine (CBZ), widely used as an antiepileptic agent, could cause rare but severe idiosyncratic liver injury in humans. Although recent studies have shown that inflammasome is implicated in CBZ-induced hepatocellular injury in vitro, the precise pathogenesis of hepatotoxicity remains largely unexplored. Here we report that CBZ causes idiosyncratic liver injury through promoting specific stimuli-induced NLRP3 inflammasome activation. CBZ (40 µM) enhances NLRP3 inflammasome activation triggered by adenosine triphosphate (ATP) or nigericin, rather than SiO2, monosodium urate crystal or intracellular lipopolysaccharide (LPS). In addition, CBZ has no effect on NLRC4 or AIM2 inflammasome activation. Mechanistically, synergistic induction of mitochondrial reactive oxygen species (mtROS) is a crucial event in the enhancement effect of CBZ on ATP- or nigericin-induced NLRP3 inflammasome activation. Moreover, the "C=C" on the seven-membered ring and "C=O" on the nitrogen of CBZ may be contribute to NLRP3 inflammasome hyperactivation and hepatotoxicity. Notably, in vivo data indicate that CBZ (50 mg/kg) causes liver injury in an LPS (2 mg/kg)-mediated susceptibility mouse model of IDILI, accompanied by an increase in caspase-1 activity and IL-1ß production, whereas the combination of CBZ and LPS does not exhibit the effect in NLRP3-knockout mice. In conclusion, CBZ specifically promotes ATP- or nigericin-induced NLRP3 inflammasome activation and causes idiosyncratic liver injury. Our findings also suggest that CBZ may be avoided in patients with NLRP3 inflammasome activation-related diseases that are triggered by ATP or nigericin, which may be risk factors for IDILI.

15.
J Colloid Interface Sci ; 560: 312-320, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31670226

RESUMO

In order to enhance the gas response of polypyrrole to NO2, the polypyrrole/Fe2O3 nanocomposites are synthesized by one-step hydrothermal route. The presence of ferric oxide in composites is demonstrated by XPS, HRTEM and TG analyses. The polypyrrole/Fe2O3 sensor exhibits high selectivity and response to NO2 at 50 °C. Compared with other polypyrrole/metal oxide materials, the polypyrrole/Fe2O3 materials are easy to be synthesized, and the gas sensor has a higher response of 220.7%, lower detection limit of 0.1 ppm and good linear relationship when the NO2 concentrations range from 0.1 ppm to 10 ppm. The gas response is greatly improved in comparison with the pure polypyrrole and Fe2O3. The reason for the improved response is also discussed.

16.
Surg Endosc ; 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31741161

RESUMO

BACKGROUND: As a key landmark during laparoscopic right colectomy, the classification and variation of the gastrocolic trunk of Henle (GTH) remains to be clarified. The aim of this nationwide multicenter study was to describe the characteristics of the GTH intra-operatively during laparoscopic right colectomies. METHODS: Three hundred seventy-one patients who underwent laparoscopic right colectomies from January 2018 to March 2019 in 25 hospitals across China were enrolled in the study. The length of the GTH, the classification with a precise description of confluent tributaries, and other variations were analyzed. RESULTS: Of the 371 patients, 363 had a GTH. The proportion of type-0, type-I, type-II, and type-III was 15.2% (n = 55), 54.8% (n = 199), 25.3% (n = 92), and 4.7% (n = 17), respectively. The average length of the GTH was 8.5 mm, ranging from 2 to 30 mm. CONCLUSIONS: This is the first multicenter study with a large sample by which the GTH was classified based on laparoscopic intraoperative observation. Variations in the GTH were classified into four types based on the number of colic drainage veins (right colic, superior right colic, middle colic, accessory middle colic, and ileocolic veins), among which the right colic vein was the most common. The length of the GTH was relatively short, and thus might carry a risk of bleeding. Further clinical data should be correlated with the characteristics of the GTH.

17.
Food Funct ; 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31750469

RESUMO

This work was aimed at the evaluation of stability of components in oleogels and providing a quick, visual description of the relationship between the composition of an oleogel and its thermal and oxidation properties. Composition stability analysis indicated that almost all oleogel components, including approximately 24 fatty acids (FAs), seven diglycerides (DAGs), 21 triglycerides (TAGs) and 19 lignans, were inherited from the precursor oil. The oil content among different oleogels ranged from 56.17 to 82.25%, and the oleogels made with candlestick wax (CW) showed higher component stability. Non-isothermal crystallization (C), melting (M) and oxidation analysis of the oleogels by differential scanning calorimetry (DSC) showed slight differences among the various oleogels. For visual analysis, seven components had significant positive relationships with k(Ts) and Ea(Ts), and 18 FAs, 10 glycerides and four lignans had significant positive relationships with k(Tp) and Ea(Tp). As for C(Tp) and C(ΔH), nine lignans, 13 glycerides and three FAs exhibited a notable positive correlation with k(Tp). These results might provide guidance for designing oleogel features and a new application perspective on the stability of solidified oils.

18.
Environ Int ; 133(Pt B): 105231, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31678905

RESUMO

BACKGROUND: Short-chain chlorinated paraffins (SCCPs) used in various industrial applications have been listed as new POPs. Previous studies based on high-dose exposures indicate their hepatotoxicity. However, their mechanisms of toxicity or adverse outcome pathways and health risks remain largely unknown. OBJECTIVES: This study aimed to evaluate metabolic consequences of chronic dietary exposure to SCCPs at low doses and reveal the molecular mechanisms underlying hepatotoxicity of SCCPs. METHODS: A combination of transcriptomics and metabolomics, together with general pathophysiological tests were performed to assess the hepatic response of male rats exposed to SCCPs. RESULTS: Our results highlight two major modes of action: Inhibition of energy metabolism and activation of the peroxisome proliferator-activated receptor α (PPARα). Exposure to SCCPs suppressed oxidative phosphorylation, glycolysis, gluconeogenesis and turnover of ATP-ADP-AMP and thus results in deficiencies of amino acids and nucleotides in liver of the rat. Exposure to SCCPs affected expression levels of 13 genes downstream of PPARα that encode proteins associated with metabolism of fatty acids. As a result, peroxisomal and mitochondrial fatty acid ß-oxidation, microsomal fatty acid ω-oxidation, and lipogenesis were accelerated. CONCLUSIONS: Results of this work strongly support the conclusion that low-dose exposure to SCCPs can result in adverse outcomes in the rat model. Significant SCCP-induced inhibition of energy metabolism occurs at environmentally relevant dosages, which suggests that SCCPs exhibit metabolic toxicity. Interactions of SCCPs with PPARα signaling pathway can explain the disruption of lipids and amino acids metabolism.

19.
Artigo em Inglês | MEDLINE | ID: mdl-31705175

RESUMO

PURPOSE: Accurate evaluation of hypoxia is particularly important in patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy. The aim of this study was to propose a novel imaging strategy for quantitative three-dimensional (3D) evaluation of hypoxia in a small animal model of NPC. METHODS: A carbonic anhydrase IX (CAIX)-specific molecular probe (CAIX-800) was developed for imaging of hypoxia. Mouse models of subcutaneous, orthotopic, and spontaneous lymph node metastasis from NPC (5 mice per group) were established to assess the imaging strategy. A multi-modality imaging method that consisted of a hybrid combination of fluorescence molecular tomography-computed tomography (FMT-CT) and multispectral optoacoustic tomography (MSOT) was used for 3D quantitative evaluation of tumour hypoxia. Magnetic resonance imaging, histological examination, and immunohistochemical analysis were used as references for comparison and validation. RESULTS: In the early stage of NPC (2 weeks after implantation), FMT-CT enabled precise 3D localisation of the hypoxia biomarker with high sensitivity. At the advanced stage (6 weeks after implantation), MSOT allowed multispectral analysis of the biomarker and haemoglobin molecules with high resolution. The combination of high sensitivity and high resolution from FMT-CT and MSOT could not only detect hypoxia in small-sized NPCs but also visualise the heterogeneity of hypoxia in 3D. CONCLUSIONS: Integration of FMT-CT and MSOT could allow comprehensive and quantifiable evaluation of hypoxia in NPC. These findings may potentially benefit patients with NPC undergoing radiotherapy in the future. Graphical abstract A novel multimodality imaging strategy for three-dimensional evaluation of tumour hypoxia in an orthotopic model of nasopharyngeal carcinoma.

20.
J Hazard Mater ; : 121652, 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31761647

RESUMO

Chlorine bleaching of non-wood pulp can produce and release polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into environment. In this study, a series of chlorination experiments were conducted to explore the source, formation pathway and formation kinetics of Cl1-8DD/Fs during the chlorine bleaching of wheat straw pulp. The 13C isotope-labeling experiment verified that PCDD/Fs could not be formed from the chlorination of phenols in pulp. Above 80% of the observed PCDFs originated from the direct chlorination of dibenzofuran (DBF) in unbleached wheat straw pulp, while approximately 60% of the observed PCDDs came from the chlorination of nonextractable precursors in the pulp. The yield of total PCDFs was 2 orders of magnitude higher than that of total PCDDs. The kinetic study indicated that DBF was more easily chlorinated than dibenzo-p-dioxin (DBD) in the pulp solution. Pseudo-first-order reaction kinetic equations fitted the formation and degradation of PCDD/Fs well. The direct chlorination of DBD/F primarily preferred a selective pattern at the 2 position, followed by the 8, 7 and 3 positions. A higher content of DBF in unbleached pulp led to a higher yield of 2,3,7,8-Cl4DF. Finally, the practical implication for dioxin formation control was discussed.

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