•NMFs from WEEE were treated by incineration or land filling in the past.•Environmental risks such as heavy metals and BFRs will be the major problems during the NMFs recycling processes.•Methods and ...technologies of recycling the two types of NMFs from WEEE, plastics, glasses are reviewed.•More environmental impact assessment should be carried out to evaluate the environmental risks of the recycling products.
The world’s waste electrical and electronic equipment (WEEE) consumption has increased incredibly in recent decades, which have drawn much attention from the public. However, the major economic driving force for recycling of WEEE is the value of the metallic fractions (MFs). The non-metallic fractions (NMFs), which take up a large proportion of E-wastes, were treated by incineration or landfill in the past. NMFs from WEEE contain heavy metals, brominated flame retardant (BFRs) and other toxic and hazardous substances. Combustion as well as landfill may cause serious environmental problems. Therefore, research on resource reutilization and safe disposal of the NMFs from WEEE has a great significance from the viewpoint of environmental protection. Among the enormous variety of NMFs from WEEE, some of them are quite easy to recycle while others are difficult, such as plastics, glass and NMFs from waste printed circuit boards (WPCBs). In this paper, we mainly focus on the intractable NMFs from WEEE. Methods and technologies of recycling the two types of NMFs from WEEE, plastics, glass are reviewed in this paper. For WEEE plastics, the pyrolysis technology has the lowest energy consumption and the pyrolysis oil could be obtained, but the containing of BFRs makes the pyrolysis recycling process problematic. Supercritical fluids (SCF) and gasification technology have a potentially smaller environmental impact than pyrolysis process, but the energy consumption is higher. With regard to WEEE glass, lead removing is requisite before the reutilization of the cathode ray tube (CRT) funnel glass, and the recycling of liquid crystal display (LCD) glass is economically viable for the containing of precious metals (indium and tin). However, the environmental assessment of the recycling process is essential and important before the industrialized production stage. For example, noise and dust should be evaluated during the glass cutting process. This study could contribute significantly to understanding the recycling methods of NMFs from WEEE and serve as guidance for the future technology research and development.
A viscoelastic model is proposed to describe the propagation of gravity waves into various types of ice cover. The ice‐ocean system is modeled as a homogeneous viscoelastic fluid overlying an ...inviscid layer. Both layers have finite thickness. The viscosity is imagined to originate from the frazil ice or ice floes much smaller than the wavelength, and the elasticity from ice floes which are relatively large compared to the wavelength. A compact form of the dispersion relation is obtained. Under proper limiting conditions this dispersion relation can be reduced to several previously established models including the mass loading model, the viscous layer model and the thin elastic plate model. The full dispersion relation contains several propagating wave modes under the ice cover. The following two criteria are used to select the dominant wave mode: (1) wave number is the closest to the open water value and (2) attenuation rate is the least among all modes. The modes selected from those criteria coincide with the ones discussed in previous studies, which are shown to be limiting cases in small or large elasticity regimes of the present model. In the intermediate elasticity regime, however, it appears that there are three wave modes with similar wavelengths and attenuation rates. Implications of this intermediate elasticity range remain to be seen. The general viscoelastic model bridges the gap among existing models. It also provides a unified tool for wave‐ice modelers to parameterize the polar regions populated with various types of ice cover.
Pulsed discharge plasma and its application is one of the promising directions in civilian areas of pulsed power technology. In order to promote the research and development of the theory and ...application technology for pulsed discharge plasma, in this paper, recent progress on the mechanism of nanosecond-pulse gas discharge and the characteristics and applications of typical pulsed plasma at the Institute of Electrical Engineering, Chinese Academy of Sciences is reviewed. Firstly, progress on mechanism of nanosecond-pulse discharge based on runaway electrons and measurement technology of runaway electrons is introduced. Then, the characteristics of three typical discharges, including direct-driven pulsed discharge, pulsed dielectric barrier discharge and pulsed plasma jet, are reviewed. Furthermore, typical plasma applications of pulsed plasma on surface modification and methane conversion are presented.
A novel sensing system has been designed for Cu2+ ion detection based on the quenched fluorescence (FL) signal of branched poly(ethylenimine) (BPEI)-functionalized carbon quantum dots (CQDs). Cu2+ ...ions can be captured by the amino groups of the BPEI-CQDs to form an absorbent complex at the surface of CQDs, resulting in a strong quenching of the CQDs’ FL via an inner filter effect. Herein, we have demonstrated that this facile methodology can offer a rapid, reliable, and selective detection of Cu2+ with a detection limit as low as 6 nM and a dynamic range from 10 to 1100 nM. Furthermore, the detection results for Cu2+ ions in a river water sample obtained by this sensing system agreed well with that by inductively couple plasma mass spectrometry, suggesting the potential application of this sensing system.
An easy bottom–up method for the preparation of photoluminescent (PL) graphene quantum dots (GQDs) and graphene oxide (GO) has been developed by tuning the carbonization degree of citric acid and ...dispersing the carbonized products into alkaline solutions. The GQDs are nanosheets ∼15nm in width, and 0.5–2.0nm in thickness. They show a relatively strong (9.0%) PL quantum yield and an excitation-independent PL emission activity. In contrast, the GO nanostructures consist of sheets that are hundreds of nanometers in width and ∼1nm in height. They exhibit a relatively weak (2.2%) PL quantum yield and an excitation-dependent PL emission activity.
Free chlorine was found to be able to destroy the passivated surface of the graphene quantum dots (GQDs) obtained by pyrolyzing citric acid, resulting in significant quenching of their fluorescence ...(FL) signal. After optimizing some experimental conditions (including response time, concentration of GQDs, and pH value of solution), a green and facile sensing system has been developed for the detection of free residual chlorine in water based on FL quenching of GQDs. The sensing system exhibits many advantages, such as short response time, excellent selectivity, wide linear response range, and high sensitivity. The linear response range of free chlorine (R 2 = 0.992) was from 0.05 to 10 μM. The detection limit (S/N = 3) was as low as 0.05 μM, which is much lower than that of the most widely used N-N-diethyl-p-phenylenediamine (DPD) colorimetric method. This sensing system was finally used to detect free residual chlorine in local tap water samples. The result agreed well with that by the DPD colorimetric method, suggesting the potential application of this new, green, sensitive, and facile sensing system in drinking water quality monitoring.
In this paper, an atmospheric-pressure dielectric barrier discharge is used to modify the surface of the epoxy material and enhance the dissipation of surface charge to reduce the accumulation of ...surface charge. In the experiments, atmospheric-pressure air dielectric barrier discharge is driven by a microsecond pulse generator. Surface properties of epoxy before and after the plasma treatment are characterized by water contact angle, surface potential, and surface/volume conductivity measurements. Atomic force microscope and X-ray photoelectron spectroscopy are used to investigate the changes of the morphology and the chemical composition of the epoxy surface. Experimental results indicate that the surface of epoxy is etched by the plasma and the increase of the surface roughness enhances the surface insulation ability. The O radicals in plasma and the carbonyl groups formed on the surface make the surface charge trap shallower, change the epoxy surface composition then increase the surface conductivity and accelerate surface charge dissipation. When the epoxy is treated for an appropriate time, the epoxy surface insulation performance will be enhanced obviously and the surface charge dissipation will be accelerated.
The Youjiang Basin in the western part of the South China Block (SCB), preserves the records of the tectonic history from Tethyan, through Paleo-Pacific to Tibetan domains, with coeval formation of ...diverse types of giant metallic deposits. The prolonged tectonic evolution and its control on the genesis and spatio-temporal distribution of giant metallic deposits in the Youjiang Basin provide a window for a holistic understanding of the tectono-metalligenesis of SCB. Six tectono-metallogenic stages can be recognized in the geological evolution of the basin and their relationship to the geodynamic evolution of the surrounding tectonic units. Subsequent to the closure of the Proto-Tethyan Ocean and collision between the SCB and the Gondwana continent, a late Ordovician to early Silurian intracontinental orogeny along the southern margin of the basin resulted in the formation of Silurian Cu and W skarn deposits. During Devonian to Carboniferous, during the Paleo-Tethyan spreading, the basin experienced rifting and development of a passive continental margin, when sedimentary Mn carbonate ores were deposited in basin facies sequences in the southern part of the basin. On the northern margin, bauxite karsts formed in carbonate rocks within continental-margin sequences. In the Late Permian, the Paleo-Pacific oceanic plate was subducted below the SCB, which most likely induced migration of the coeval Emeishan mantle plume towards the plate margin. Arc volcanism resulted in voluminous ash falls on the carbonate platform and these were subsequently transformed into bauxite in the southern part of basin. Following this, Triassic intraplate shortening induced thin-skinned crustal deformation with associated formation of orogenic Au deposits throughout the basin. In the Jurassic, the Youjiang Basin experienced slab delamination, during which MVT PbZn deposits formed along the northern margin, and clusters of WSn skarns were generated at the centre of the delamination zone on the eastern margin of the basin. Subduction retreated southwards in the Cretaceous, resulting in the formation of Carlin-type Au deposits in the northern part of the basin, and Sn and Cu skarns and associated carbonate replacement PbZn deposits in the central and southern parts. Cenozoic regional denudation and climate change in response to the southeastward propagation of Tibet caused brittle deformation of pre-existing bauxite and Mn orebodies and their further enrichment. The overlap among Paleo-Tethyan, Paleo-Pacific and Tibetan tectonic regimes during the evolution of the Youjiang Basin generated a diverse range of mineral deposit types, including orogenic and Carlin-type Au deposits, both carbonate-replacement and MVT-type PbZn deposits, sedimentary Mn‑carbonate deposits and bauxite in both passive and active continental margins.
•Holistic evaluation of Tethyan, Paleo-Pacific and Tibetan tectonic regimes in the Youjiang basin.•Early Paleozoic Mn and Al deposits formed in continental extensional setting.•Permian oceanic subduction induced continental arc magmatism and subsequent bauxite formation.•Triassic shortening and post-collisional extension formed orogenic gold mineralization.•Cretaceous slab retreat formed earlier Carlin-type gold deposits and later Sn skarns.
AFM observation of untreated and treated PMMA films: (a) untreated, (b) Ar plasma treated after 90s and (c) He plasma treated after 90s. The right side figures showed the larger version of the ...selected area.
•The He plasma treated PMMA showed better hydrophilic property and slower aging effect than that of Ar plasma treated PMMA.•The He plasma was composed with higher intensity of reactive species, like OH, O, N2 and N2+ than that of Ar plasma.•The roughness of PMMA increased and granule-like hills appeared on the surface after plasma treatment.•Both He and Ar plasma treatment introduced O and N elements on the PMMA surface.•These physical and chemical modifications are responsible for the hydrophilic treatment of PMMA surface.
In this paper, a plasma jet driven by an in-house developed microsecond pulse is used for polymethyl methacrylate (PMMA) surface modification. The hydrophilic modification effects of He and Ar plasma jets are compared under the same condition. The He and Ar plasma jets are characterized by optical emission spectrometer (OES). Water contact angle (WCA) measurement is used to evaluate the wettability of PMMA samples. The evolution on morphology and chemical composition of PMMA before and after plasma treatment are also analyzed. The OES results demonstrate that He plasma is composed with higher intensities of reactive species, like OH, O, N2 and N2+ than that of Ar plasma and show a better modification effect. In addition, it is observed that the surface roughness and oxygen-containing groups like CO/COH and OCO increase on the PMMA surface after plasma treatment, which are responsible for the hydrophilic modification. During the storage, the WCA of each sample increases gradually for both He and Ar plasma treatments. The He plasma treated PMMA also shows a slower aging effect than that of Ar plasma treated PMMA.
Patients with advanced esophageal cancer have a poor prognosis and limited treatment options after first-line chemotherapy.
In this open-label, phase III study, we randomly assigned (1:1) 628 ...patients with advanced/metastatic squamous cell carcinoma or adenocarcinoma of the esophagus, that progressed after one prior therapy, to pembrolizumab 200 mg every 3 weeks for up to 2 years or chemotherapy (investigator's choice of paclitaxel, docetaxel, or irinotecan). Primary end points were overall survival (OS) in patients with programmed death ligand-1 (PD-L1) combined positive score (CPS) ≥ 10, in patients with squamous cell carcinoma, and in all patients (one-sided α 0.9%, 0.8%, and 0.8%, respectively).
At final analysis, conducted 16 months after the last patient was randomly assigned, OS was prolonged with pembrolizumab versus chemotherapy for patients with CPS ≥ 10 (median, 9.3
6.7 months; hazard ratio HR, 0.69 95% CI, 0.52 to 0.93;
= .0074). Estimated 12-month OS rate was 43% (95% CI, 33.5% to 52.1%) with pembrolizumab versus 20% (95% CI, 13.5% to 28.3%) with chemotherapy. Median OS was 8.2 months versus 7.1 months (HR, 0.78 95% CI, 0.63 to 0.96;
= .0095) in patients with squamous cell carcinoma and 7.1 months versus 7.1 months (HR, 0.89 95% CI, 0.75 to 1.05;
= .0560) in all patients. Grade 3-5 treatment-related adverse events occurred in 18.2% of patients with pembrolizumab versus 40.9% in those who underwent chemotherapy.
Pembrolizumab prolonged OS versus chemotherapy as second-line therapy for advanced esophageal cancer in patients with PD-L1 CPS ≥ 10, with fewer treatment-related adverse events.
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