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1.
Sci Total Environ ; 754: 142136, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32911157

RESUMO

Porous biochars have attracted tremendous interests in electrochemical applications. In this study, a family of biochars were prepared from cellulose subject to different carbonization temperatures ranging from 400 to 700 °C, and the biochars were in-situ activated by a molten salt (ZnCl2) to construct a hierarchically porous architecture. The activated porous biochars (ZnBC) were used as a carbocatalyst for electro-Fenton (EF) oxidation of organic contaminants. Results showed that high-temperature carbonization improved the activity of biochar for four-electron oxygen reduction reaction (ORR) due to the rich carbon defects, while the mild-temperature treatment regulated the species and distribution of oxygen functional groups to increase the production of hydrogen peroxide (H2O2) via a selective two-electron ORR pathway. ZnBC-550 was the best cathode material with a high ORR activity without compromise in H2O2 selectivity; a high production rate of H2O2 (796.1 mg/g/h) was attained at -0.25 V vs RHE at pH of 1. Furthermore, Fe(II) addition induced an electro-Fenton system to attain fast decomposition of various organic pollutants at -0.25 V vs RHE (reversible hydrogen electrode) and pH of 3 with a satisfactory mineralization efficiency toward phenolic pollutants. The EF system maintains its excellent stability for 10 cycles. Hydroxyl radicals were identified as the dominant reactive oxygen species based on in situ electron paramagnetic resonance (EPR) analysis and radical quenching tests. This study gains new insights into electrocatalytic H2O2 production over porous biochars and provides a low-cost, robust and high-performance electro-Fenton cathode for wastewater purification.

2.
Water Res ; 186: 116361, 2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32927420

RESUMO

Plasticizer pollution in drinking water and aquatic systems has raised global concerns due to the lasting and chronic hazards to marine life and public health. Metal-free materials are promising as green catalysts for wastewater purification. In this study, amorphous boron was applied as a metal-free activator to decompose peroxymonosulfate (PMS) for the degradation of plasticizers in water. Integrating radical trapping and selectively quenching tests with kinetic evaluation and electrochemical analysis, hydroxyl radical was found to be the dominating reactive oxygen species (ROS). With a strong oxidative capacity, the boron/PMS system can effectively degrade both bisphenols and phthalates plasticizers. In contrast, a carbon nanotube-catalyzed PMS system mediated a nonradical pathway to oxidize the electron-rich plasticizer (bisphenol A), but ineffectively to decompose the highly recalcitrant phthalates plasticizers (diethyl phthalate). Moreover, we unveiled that the boron surface was oxidized to boron oxide during the redox reaction, and the oxide would be self-cleaned in the acidic solution to regenerate fresh boron and restore the activity during the cyclic operations. Therefore, this work not only gains new insights into the radical and nonradical oxidations by metal-free catalysis, but also provides feasible technologies for plasticizer purification in water.

3.
Water Res ; 185: 116244, 2020 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-32750570

RESUMO

A rational design of structure-tailored and functionalized nanocarbons for peroxymonosulfate (PMS) activation is important in metal-free catalysis for degradation of water contaminants. In this work, we employed ionic liquids (ILs) for synthesis of porous carbon materials (PCMs) as a PMS activator for oxidative removal of naproxen and systematically investigated the functions of structure defects, oxygen functional groups and heteroatom doping toward the catalytic oxidation. A positive linear correlation between reaction rate constants and carbon defect ratios of PCMs revealed that the structural defects played an important role in PMS activation. Electron paramagnetic resonance (EPR) spectra, radical quenching experiments and electrochemical analysis tests verified nonradical-dominated oxidations via electron transfer and 1O2. Structural vacancies, ketonic C=O groups and graphitic-N atoms on carbons have been revealed to be the active sites for the nonradical pathways via direct electron transfer or generation of O2•-/1O2. This work provides new insight into the reaction mechanism and structure-performance relationships of the catalytic centers in nonradical oxidation.

4.
Soc Sci Med ; 263: 113287, 2020 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-32818850

RESUMO

Economic factors and health care resources are important influential factors of infant mortality. We aimed to examine prefecture-level spatial heterogeneity and clustering of the associations of economic and health care factors with infant mortality rates (IMR) in China. IMR data in 348 prefectures were calculated and adjusted, and economic and health care data were collected in each prefecture in China, 2010. Stepwise regression was used to select important variables, and geographically weighted regression (GWR) was applied to examine the spatial variations of the relationships between economic and health care factors and IMR. The k-means clustering was developed to elucidate the spatial clustering patterns of the GWR coefficients. The results showed that three important variables were selected in the multivariable regression model, including per capita income of rural residents, Engel's coefficient of rural residents, and proportion of government health expenditure. The GWR with these three variables revealed spatial heterogeneity of the associations between IMR and economic and health care factors; western China generally had higher GWR R-squares and stronger associations between IMR and all the three variables than the middle-eastern part of China. Based on the GWR coefficients, three distinct spatial clusters were identified. This study contributes new findings on the spatial heterogeneity of the associations between economic and health care factors and infant mortality rate in China, which calls for region-specific policies to reduce infant mortality in China.

5.
Invest Ophthalmol Vis Sci ; 61(10): 4, 2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32749462

RESUMO

Purpose: Azidothymidine (AZT), a nucleoside reverse transcriptase inhibitor, possesses anti-inflammatory and anti-angiogenic activity independent of its ability to inhibit reverse transcriptase. The aim of this study was to evaluate the efficacy of 5'-glucuronyl azidothymidine (GAZT), an antiretrovirally inert hepatic clinical metabolite of AZT, in mouse models of retinal pigment epithelium (RPE) degeneration and choroidal neovascularization (CNV), hallmark features of dry and wet age-related macular degeneration (AMD), respectively. Methods: RPE degeneration was induced in wild-type (WT) C57BL/6J mice by subretinal injection of Alu RNA. RPE degeneration was assessed by fundus photography and confocal microscopy of zonula occludens-1-stained RPE flat mounts. Choroidal neovascularization was induced by laser injury in WT mice, and CNV volume was measured by confocal microscopy. AZT and GAZT were delivered by intravitreous injections. Inflammasome activation was monitored by western blotting for caspase-1 and by ELISA for IL-1ß in Alu RNA-treated bone marrow-derived macrophages (BMDMs). Results: GAZT inhibited Alu RNA-induced RPE degeneration and laser-induced CNV. GAZT also reduced Alu RNA-induced caspase-1 activation and IL-1ß release in BMDMs. Conclusions: GAZT possesses dual anti-inflammatory and anti-angiogenic properties and could be a viable treatment option for both forms of AMD.

6.
J Hazard Mater ; 401: 123423, 2020 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-32763710

RESUMO

Developing efficient and robust materials for emerging electrodegradation of organic pollutants has attracted broad interests. In this study, a novel controlled pyrolysis approach was employed to fabricate a quasi-MOF derivative-based electrode by pyrolyzing MIL-101(Fe) anchored on a polyaniline-modified carbon fiber paper at 400 °C. The construction of the accessible Fe-O sites, and the in situ generation of Fe3O4 nanoparticles with graphene-like carbon layers coated, would enhance the electro-Fenton activity of the electrode, which was used as the cathode. The results showed that 100 % of 50 mg L-1 p-nitrophenol and 52 % total organic carbon were removed in 120 min under a current density of 5 mA cm-2, suggesting that the prepared electrode had a more efficient mineralization current efficiency and less energy consumption compared with electrodes before pyrolysis. Notably, the stability of the electrode was greatly improved, maintaining its outstanding performance even after ten runs. The plausible reaction mechanism and degradation pathway were also proposed. This new pyrolysis strategy is expected to serve as a paradigm for designing efficient electrode in electro-Fenton remediation field.

7.
Adv Clin Exp Med ; 29(7): 879-886, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32745379

RESUMO

BACKGROUND: The prognostic value and non-invasive predictors of splenomegaly in cirrhotic patients with hepatocellular carcinoma (HCC) after curative resection remain unknown. OBJECTIVES: To investigate the prognostic value and non-invasive predictors of splenomegaly in cirrhotic patients with HCC after curative resection. MATERIAL AND METHODS: The medical records of 78 patients with HCC and liver cirrhosis who underwent curative resection were retrospectively reviewed. The influence of spleen size, measured with clinically routine ultrasonography (USG), on overall and disease-free survival was evaluated using univariate and multivariate analyses. The efficiency of some frequently used blood-derived liver function parameters and non-invasive fibrosis markers to predict splenomegaly was also assessed. RESULTS: It was shown that tumor size >5 cm, the presence of microvascular invasion, tumor-node metastasis (TNM) stage III-IVA of the tumor, spleen size >11.45 cm, and age ≤52 years were associated with poor overall survival and/or disease-free survival in univariate analyses (all p < 0.05). In multivariate analyses, spleen size was identified as an independent predictor for both overall and disease-free survival (p < 0.001 and p = 0.012, respectively). On the other hand, platelet count, aspartate aminotransferase (AST) to platelet ratio index (APRI) and Fibrosis-4 index (FIB-4) scores were significantly different between small and large spleen groups (p = 0.026, 0.003 and 0.003, respectively), while statistical differences for albumin, alanine aminotransferase (ALT), AST, total bilirubin, AST to ALT ratio (AAR), and age-platelet index (API) were not found. Using receiver operating characteristic (ROC) curves, high powers of platelet count, APRI and FIB-4 in splenomegaly prediction were confirmed. CONCLUSIONS: Splenomegaly, which can be predicted by some non-invasive variables, serves as a strong determinant for postresectional prognoses of cirrhotic patients with HCC.

8.
Adv Clin Exp Med ; 29(7): 887-892, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32750753

RESUMO

BACKGROUND: Microvascular invasion (MVI) is a significant sign of the invasive property and a strong predictor of poor prognosis in hepatocellular carcinoma (HCC), a life-threatening malignancy. However, recurrence-associated and post-surgical long-term prognosis-associated factors in HCC with MVI remain unknown. OBJECTIVES: To address the abovementioned issues, based on a Chinese patient cohort with HCC after curative hepatic resection. MATERIAL AND METHODS: The patient cohort consisted of 62 consecutive patients with HCC and MVI who underwent curative hepatic resection. The associations between clinicopathologic variables and recurrence, as well as patient overall/disease-free survival, were uniand multivariately evaluated. RESULTS: Univariate χ2 test identified hepatitis B surface antigen (HBsAg) positivity, high Edmondson-Steiner grade and male gender as risk factors of recurrence, whereas Edmondson-Steiner grade and HBsAg positivity were significant or marginally significant in the multivariate stepwise logistic regression analysis. Subsequently, univariate log-rank test showed that Edmondson-Steiner grade, HBsAg positivity and Child-Pugh grade were associated with overall and/or disease-free survival. Among them, the independent prognostic impact of Edmondson-Steiner grade and HBsAg positivity for both overall and disease-free survival were proven in the multivariate Cox regression analysis. CONCLUSIONS: Our data suggested that Edmondson-Steiner grade and HBsAg positivity might serve as useful indicators of recurrence and pessimistic prognosis in HCC with MVI.

9.
Artigo em Inglês | MEDLINE | ID: mdl-32608118

RESUMO

Generation of hydroxyl radicals in the Fenton system (FeII /H2 O2 ) is seriously limited by the sluggish kinetics of FeIII reduction and fast FeIII precipitation. Here, boron crystals (C-Boron) remarkably accelerate the FeIII /FeII circulation in Fenton-like systems (C-Boron/FeIII /H2 O2 ) to produce a myriad of hydroxyl radicals with excellent efficiencies in oxidative degradation of various pollutants. The surface B-B bonds and interfacial suboxide boron in the surface B12 icosahedra are the active sites to donate electrons to promote fast FeIII reduction to FeII and further enhance hydroxyl radical production via Fenton chemistry. The C-Boron/FeIII /H2 O2 system outperforms the benchmark Fenton (FeII /H2 O2 ) and FeIII -based sulfate radical systems. The reactivity and stability of crystalline boron is much higher than the popular molecular reducing agents, nanocarbons, and other metal/metal-free nanomaterials.

10.
J Hazard Mater ; 399: 123043, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32526439

RESUMO

In this work, the cellulose-enriched mesocarp of tangerine peels (TP) and the lignin-enriched epicarp of the peels (e-TPs) were used as examples to unveil the link between the basic components (cellulose, hemicellulose and lignin) in lignocellulosic biomass and catalytic activity of biochar towards peroxymonosulfate (PMS) activation. The TP biochar exhibits sheet-like morphology and high porosity, while the e-TPs biochar shows a bulk morphology. Accordingly, the former outperformed the latter in terms of catalytic degradation of phenol with PMS, attributing to the higher content of cellulose than lignin in the TP precursor, which was further supported by comparing the catalytic activity of biochar prepared from binary mixtures containing different proportions of cellulose and lignin. Nonradical oxidation pathway based on singlet oxygen (1O2) and electron-transfer mechanism was involved in the TP biochar/PMS system and the key role of CO group in biochar for 1O2 generation was computationally demonstrated. Additionally, the unique porous structure and surface chemistry of TP biochar endows it an excellent adsorbent for various organic pollutants. Herein, this work provides an insight into the effect of lignocellulosic biomass source on the catalytic property of biochar, which would be beneficial to screen lignocellulosic biowastes to prepare high-performance biochar for water remediation.

11.
Environ Sci Technol ; 54(13): 8464-8472, 2020 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-32519855

RESUMO

Nanocarbon-based persulfate oxidation emerges as a promising technology for the elimination of organic micropollutants (OMPs). However, the nature of the active site and its working mechanism remain elusive, impeding developments of high-performance oxidative technology for water treatment practice. Here, we report that defect-rich carbon nanotubes (CNTs) exhibit a superior activity in the activation of peroxymonosulfate (PMS) for OMP oxidation. Quantitative structure-activity relationship studies combined with theoretical calculations unveil that the double-vacancy defect on CNTs may be the intrinsic active site, which works as a conductive bridge to facilitate the potential difference-dominated electron transfer from the highest occupied molecular orbital of OMPs to the lowest unoccupied molecular orbital of PMS. Based on this unique mechanism, the established CNTs@PMS oxidative system achieves outstanding selectivity and realizes the target-oriented elimination of specific OMPs in a complicated aquatic environment. This work sheds new light on the mechanism of carbocatalysis for selective oxidation and develops an innovative technology toward remediation of practical wastewater.

12.
Chemosphere ; 256: 127160, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32464363

RESUMO

Bimetallic oxide nanomaterials have received much attention owing to their competing performances in heterogeneous catalysis. Herein, hierarchically porous cobalt-iron oxide nanosheets were successfully prepared using NaBH4 as a reductant and high concentration cetyl trimethylammonium bromide (CTAB) as a surfactant. Characterization results showed that the CTAB would induce the form of a bilayer structure while NaBH4 would promote the generation of enriched oxygen vacancies. As a result, the as-prepared Co1Fe1-300 exhibited high activity for activating peroxymonosulfate and achieved 100% phenol degradation within 30 min. This excellent catalytic activity can be attributed to its hierarchically porous structure, more active sites and oxygen vacancies. Co leaching test indicated that the Co1Fe1-300 exhibited excellent catalytic stability. Mechanistic studies suggested that two main degradation pathways were involved during phenol oxidation process, in which SO4•- played a significant role. This work may offer a novel strategy for the synthesis of high activity catalysts and a promising system for the remediation of environmental pollutant.


Assuntos
Cobalto/química , Recuperação e Remediação Ambiental/métodos , Compostos Férricos/química , Óxidos/química , Peróxidos/química , Fenol/análise , Fenol/metabolismo , Catálise , Ferro/química , Nanopartículas Metálicas/química , Compostos Orgânicos , Oxirredução , Fenóis , Porosidade
13.
Soc Sci Med ; 253: 112963, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32289647

RESUMO

The world's population is aging rapidly. In this paper, three population aging indicators were collected to represent the elderly population, the oldest-old population, and centenarians. The spatial patterns of three population aging indicators and the influencing social-economic factors and their spatial spillover effects in the world from 1990 to 2010 were investigated. The empirical strategy was based on application of spatial autocorrelation methods and spatial error modeling. The results revealed the significant positive spatial autocorrelation as well as the obvious spatial disparities and clusters of the aging indicators in the world. Furthermore, spatial spillover effects of population aging indicators were detected with positive influence of several social-economic factors (e.g., per capita GNI, urbanization rate, and life expectancy) not only of population aging in a country itself, but in its neighboring counties. In sum, these findings indicated that population aging are a spatio-temporal process, and the spatial spillover effects from neighbors also vary among these indicators, which should be considered into the differentiated policies in response to the challenge of an aging society.

14.
J Hazard Mater ; 395: 122695, 2020 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-32330786

RESUMO

In this study, carbon quantum dots (CQDs) were synthesized by a low-cost and scalable approach and the oxygen functional groups were fine-tuned by chemical post-treatment. It was found that the CQDs could be applied as visible-light-responsive photocatalysts for activation of peroxymonosulfate (PMS) and remediation of aqueous organic dyes. Phenylhydrazine modified CQDs (CQDs-PH) presented high efficiency for degradation of methylene blue due to selective removal of carboxylic groups and inhibited recombination of photogenerated electron-hole pairs. The effects of catalyst dosage, species and concentrations of dyes, and initial pH values on the photodegradation efficiency were systematically investigated and the alkaline condition facilitates the separation of photoinduced charge carriers and promotes the dye decoloration. The reactive oxygen species produced in the photocatalysis were identified by radical quenching tests and the mechanism was elucidated. Superoxide radicals were generated from PMS activation via electron transfer from CQDs and played the primary role in organic oxidation. In addition, photogenerated holes on the valence band of CQDs also participated in the dye decomposition.

15.
Environ Sci Technol ; 54(10): 6438-6447, 2020 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-32302479

RESUMO

Persulfates activation by carbon nanotubes (CNT) has been evidenced as nonradical systems for oxidation of organic pollutants. Peroxymonosulfate (PMS) and peroxydisulfate (PDS) possess discrepant atomic structures and redox potentials, while the nature of their distinct behaviors in carbocatalytic activation has not been investigated. Herein, we illustrated that the roles of nitrogen species in CNT-based persulfate systems are intrinsically different. In PMS activation mediated by nitrogen-doped CNT (N-CNT), surface chemical modification (N-doping) can profoundly promote the adsorption quantity of PMS, consequently elevate potential of derived nonradical N-CNT-PMS* complexes, and boost organic oxidation efficiency via an electron-transfer regime. In contrast, PDS adsorption was not enhanced upon incorporating N into CNT due to the limited equilibrium adsorption quantity of PDS, leading to a relatively lower oxidative potential of PDS/N-CNT system and a mediocre degradation rate. However, with equivalent persulfate adsorption on N-CNT at a low quantity, PDS/N-CNT exhibited a stronger oxidizing capacity than PMS/N-CNT because of the intrinsic higher redox potential of PDS than PMS. The oxidation rates of the two systems were in great linearity with the potentials of carbon-persulfate* complexes, suggesting N-CNT activation of PMS and PDS shared the similar electron-transfer oxidation mechanism. Therefore, this study provides new insights into the intrinsic roles of heteroatom doping in nanocarbons for persulfates activation and unveils the principles for a rational design of reaction-oriented carbocatalysts for persulfate-based advanced oxidation processes.

16.
Nanoscale ; 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32196063

RESUMO

Polymeric carbon nitrides (PCNs) are promising photocatalysts and electrocatalysts for water oxidation, as they are environmentally benign materials with an adjustable structure and facilely synthesized from inexpensive and abundant starting materials. In this minireview, we examine the state-of-the-art strategies for tailoring PCNs for efficient photocatalytic, electrocatalytic, and photoelectrochemical water oxidation, including heteroatom doping and interface engineering from band structure alignment (e.g., by coupling inorganic or organic semiconductors) to hybridization with nanoscale cocatalysts (e.g., nanosheets, nanoarrays, nanoparticles, and quantum dots) and sub-nanoscale cocatalysts (e.g., metallic molecular clusters and single-atom catalysts). Through establishing the structure-activity correlations, we aim to present a clear roadmap for providing insights into the design strategies, structure modification, and the improved catalytic performances of PCN-based materials in different catalytic water oxidation processes. For future guidance, we also propose some outlooks on the perspective and challenges of PCNs towards a better application in catalytic water oxidation.

17.
J Colloid Interface Sci ; 569: 12-21, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32097798

RESUMO

Organic contaminants, dyes and antibiotics, discharged in wastewater systems, have posed great threats to the sustainability of the ecosystem. This study was performed to prepare graphitic carbon nitride (GCN) nanocomposites modified by nanocarbons, including carbon quantum dots (CQD), carbon nanotube (CNT), reduced graphene oxide (rGO), and carbon nanospheres (CNS), by a straightforward one-pot method. The characterization results suggest that after the modification with nanocarbons, GCN demonstrated slight red shift and stronger light absorption. The resultant photocatalysts revealed prominent performances for total photodegradation of organic contaminants. The degradation processes were investigated by in situ electron paramagnetic resonance (EPR). The mechanistic studies on the enhanced photoelectrochemical and photocatalytic performances were also conducted. Results indicate that GCN modified by the nanocarbon spheres displayed a substantial improvement in the degradation of sulfachloropyridazine (SCP) and dyes, compared favourably with other GCN samples modified by carbon nanotubes, quantum dots and layered graphene oxide. The photocatalytic degradation difference is mainly stemmed from the higher contents of COOH and CO functional groups. The intimate contact or interaction between the two phases of GCN and nanocarbon in the nanocomposites may further improve the activity. This work provides insight in the design of highly efficient metal-free photocatalysts to better utilise the clean and free solar energy for environmental remediation.

18.
Blood ; 135(20): 1783-1787, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31977004

RESUMO

Vaso-occlusive crisis (VOC) is the primary cause of morbidity and hospitalization in sickle cell disease (SCD); however, only 4 therapies (hydroxyurea, l-glutamine, crizanlizumab, and voxeletor) are currently approved in SCD. These agents limit the duration, severity, and frequency of crises. Activation of coagulation is a hallmark of SCD. Studies in animal models of SCD have shown that coagulation contributes to the chronic inflammation and end-organ damage associated with the disease; however, it is unknown whether coagulation directly contributes to the microvascular stasis that causes VOC. Herein, we demonstrate that inhibition of tissue factor (TF) and the downstream coagulation proteases factor Xa and thrombin significantly attenuates heme-induced microvascular stasis in mouse models of VOC. Pharmacologic inhibition of the principal thrombin receptor, protease activated receptor-1 (PAR-1), as well as deficiency of PAR-1 in all nonhematopoietic cells, also reduces stasis in sickle mice. PAR-1 deficiency was associated with reduced endothelial von Willebrand factor expression, which has been shown to mediate microvascular stasis. In addition, TF inhibition reduces lung vaso-occlusion in sickle mice mediated by arteriolar neutrophil-platelet microemboli. In sum, these results suggest that prophylactic anticoagulation might attenuate the incidence of VOC.

19.
Phys Med ; 69: 184-191, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31918371

RESUMO

PURPOSE: We introduced and evaluated an end-to-end organs-at-risk (OARs) segmentation model that can provide accurate and consistent OARs segmentation results in much less time. METHODS: We collected 105 patients' Computed Tomography (CT) scans that diagnosed locally advanced cervical cancer and treated with radiotherapy in one hospital. Seven organs, including the bladder, bone marrow, left femoral head, right femoral head, rectum, small intestine and spinal cord were defined as OARs. The annotated contours of the OARs previously delineated manually by the patient's radiotherapy oncologist and confirmed by the professional committee consisted of eight experienced oncologists before the radiotherapy were used as the ground truth masks. A multi-class segmentation model based on U-Net was designed to fulfil the OARs segmentation task. The Dice Similarity Coefficient (DSC) and 95th Hausdorff Distance (HD) are used as quantitative evaluation metrics to evaluate the proposed method. RESULTS: The mean DSC values of the proposed method are 0.924, 0.854, 0.906, 0.900, 0.791, 0.833 and 0.827 for the bladder, bone marrow, femoral head left, femoral head right, rectum, small intestine, and spinal cord, respectively. The mean HD values are 5.098, 1.993, 1.390, 1.435, 5.949, 5.281 and 3.269 for the above OARs respectively. CONCLUSIONS: Our proposed method can help reduce the inter-observer and intra-observer variability of manual OARs delineation and lessen oncologists' efforts. The experimental results demonstrate that our model outperforms the benchmark U-Net model and the oncologists' evaluations show that the segmentation results are highly acceptable to be used in radiation therapy planning.

20.
Adv Mater ; : e1905739, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31957161

RESUMO

The structure-property engineering of phase-based materials for redox-reactive energy conversion and environmental decontamination nanosystems, which are crucial for achieving feasible and sustainable energy and environment treatment technology, is discussed. An exhaustive overview of redox reaction processes, including electrocatalysis, photocatalysis, and photoelectrocatalysis, is given. Through examples of applications of these redox reactions, how structural phase engineering (SPE) strategies can influence the catalytic activity, selectivity, and stability is constructively reviewed and discussed. As observed, to date, much progress has been made in SPE to improve catalytic redox reactions. However, a number of highly intriguing, unresolved issues remain to be discussed, including solar photon-to-exciton conversion efficiency, exciton dissociation into active reductive/oxidative electrons/holes, dual- and multiphase junctions, selective adsorption/desorption, performance stability, sustainability, etc. To conclude, key challenges and prospects with SPE-assisted redox reaction systems are highlighted, where further development for the advanced engineering of phase-based materials will accelerate the sustainable (active, reliable, and scalable) production of valuable chemicals and energy, as well as facilitate environmental treatment.

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