In this paper, a plasmonic photo-assisted electrochemical sensor, Au anchored on two-dimensional (2D) graphitic carbon nitride (g-C
3
N
4
)/reduced graphene oxide (rGO) nanosheets (Au/g-C
3
N
4
.../rGO), was facile fabricated. The morphology and structure of the composite are characterized by transmission electron microscope, X-ray photoelectron spectroscopy, X-ray diffraction and ultraviolet–visible spectrophotometer (UV–Vis). Based on the semiconductor of g-C
3
N
4
and optical properties of surface plasmon resonance for Au, the as-prepared Au/g-C
3
N
4
/rGO showed high sensitivity for the detection of trace lead ion Pb(II) by differential pulse anodic stripping voltammetry in the presence of visible light illumination. Under optimized conditions, the limit of detection (signal-to-noise ratio (
S
/
N
) = 3) Pb(II) detection can be low to 0.1 nmol·L
−1
. In addition, the interference research and real soil sample detection were measured to confirm the possibility of practical applications.
This paper proposes an autoregressive approach to harness the power of deep learning for multi-speaker monaural speech separation. It exploits a causal temporal context in both mixture and past ...estimated separated signals and performs online separation that is compatible with real-time applications. The approach adopts a learned listening and grouping architecture motivated by computational auditory scene analysis, with a grouping stage that effectively addresses the label permutation problem at both frame and segment levels. Experimental results on the WSJ0-2mix benchmark show that the new approach can achieve better signal-to-distortion ratio and perceptual evaluation of speech quality scores than most of the state-of-the-art methods for both closed-set and open-set evaluations, even methods that exploit whole-utterance statistics for separation. It achieves this while requiring fewer model parameters.
Deep learning-based speech enhancement approaches like deep neural networks (DNN) and Long Short-Term Memory (LSTM) have already demonstrated superior results to classical methods. However, these ...methods do not take full advantage of temporal context information. While DNN and LSTM consider temporal context in the noisy source speech, it does not do so for the estimated clean speech. Both DNN and LSTM also have a tendency to over-smooth spectra, which causes the enhanced speech to sound muffled. This paper proposes a novel architecture to address both issues, which we term a conditional generative model (CGM). By adopting an adversarial training scheme applied to a generator of deep dilated convolutional layers, CGM is designed to model the joint and symmetric conditions of both noisy and estimated clean spectra. We evaluate CGM against both DNN and LSTM in terms of Perceptual Evaluation of Speech Quality (PESQ) and Short-Time Objective Intelligibility (STOI) on TIMIT sentences corrupted by ITU-T P.501 and NOISEX-92 noise in a range of matched and mismatched noise conditions. Results show that both the CGM architecture and the adversarial training mechanism lead to better PESQ and STOI in all tested noise conditions. In addition to yielding significant improvements in PESQ and STOI, CGM and adversarial training both mitigate against over-smoothing.
The distribution of trays on sides of the vertical wall in the divided wall column not only affects the components separation, but also the capital investment and operation costs, which may have a ...significant effect on the simulation optimization in both (chemical) theoretical and practical studies. In this article, the effects of the patterns of trays distribution on the internal stream distribution, energy cost, and optimal operation condition are investigated and analyzed based on the theory and process simulation. According to the simulation results, there exists separation limit value on both sides of the vertical wall.
A protocol for a CoII/N,N′,N′′‐trihydroxyisocyanuric acid (THICA)‐catalyzed aerobic oxidative esterification and amidation of aldehydes has been developed. Preliminary insight into the mechanism ...indicates that such an oxidative C−O/N cross‐coupling reaction proceeds by masking the aldehyde in a nucleophilic addition reaction with an alkoxy/amino source, thereby keeping the highly reactive formyl group from undesired oxidation. This protocol for the oxidative esterification and amidation of aldehydes proceeds through two different pathways that are characterized by the intrinsic nucleophilicity of the alkanol and amine substrates The former occurs in the presence of p‐CH3C6H4SO3H as a cocatalyst and orthoformates as the alkoxy sources, instead of alkanols, to efficiently afford the transient acetals. In contrast, the coupling of the more nucleophilic amines with aldehydes renders a readily accessible cross‐coupling reaction that occurs without any cocatalyst but is limited by the potential inhibition of THICA upon nucleophilic substitution by an amine. Consequently, only sterically hindered amines were tolerated in this catalytic system, whereas further condensation occurred in the presence of primary amines to lead to imines.
Through THICA and thin: A protocol for a CoII/N,N′,N′′‐trihydroxyisocyanuric acid (THICA) mediated aerobic oxidative esterification and amidation of aldehydes has been developed. A variety of esters and amides were obtained in moderate to excellent yields by using this one‐step approach.
Biodiesel, derived from vegetable oil via hydrotreating, is becoming a promising alternative energy. Novel Ni–Mo–W/γ-Al2O3–ZSM-5 catalysts were developed and firstly applied in palm oil hydrogenation ...process. The catalysts were prepared by extrusion method and characterized by XRD, SEM, TEM, BET, NH3–TPD, and H2–TPR. The influences of acidity on the activity, selectivity, and stability of catalysts were systematically studied. The mechanisms of deoxygenation and isomerization were discussed. The catalyst Ni–Mo–W (5wt.%–5wt.%–15wt.%)/γ-Al2O3–ZSM-5 (85wt.%−15wt.%) was confirmed as the optimum one. Finally, the key reaction parameters such as reaction temperature, pressure, liquid hourly space velocity and H2/oil volume ratio were optimized. The hydrogenation reaction path of palm oil was also proposed.
•Acidity is the main factor influencing activity, selectivity, and stability of catalysts.•The diesel produced from palm oil almost conformed to the European standard EN-590.•The oxygen was principally eliminated by hydrodeoxygenation and decarbonylation.
With the strict regulation of brominated flame retardants, organophosphate esters (OPEs) have been extensively used as replacements. Increasing concerns on OPEs have aroused due to their extensive ...distribution in the environment and humans, as well as their potential toxicities. Recent studies have demonstrated that some organophosphate di-esters are even more toxic than their respective tri-esters. This review summarized the current state of knowledge on the analytical methodologies (including sample collection and preparation, instrumental analysis, and the feasibility of each potential human matrix), as well as the occurrences of OPEs and/or their metabolites (m-OPEs) in various human matrices. Organophosphate esters are readily metabolized in human thus only limited studies reported their occurrences in blood and breast milk, whereas abundant studies are available regarding the occurrences of m-OPEs rather than OPEs in urine. Since none of the matrix is suitable all the time, appropriate matrix should be selected depending on the aims of biomonitoring studies, e.g., high throughput screening or body burden estimation. Biomonitoring with non-invasive matrices such as hair and/or nail is useful to screen specific populations that might be under high exposure risks while urine is more suitable to provide valuable information on body burden. In terms of urinary monitoring, specific biomarkers have been identified for some OPE compounds, including tri(2-butoxyethyl) phosphate, tri(1,3-dichloro-2-propyl) phosphate, tri(2-chloroethyl) phosphate and tri(1-chloro-2-propyl) phosphate. Further studies are required to identify suitable urinary biomarkers for other OPE compounds, especially the emerging ones.
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•Analytical methods of OPEs and their metabolites were summarized.•Pollution status of OPEs and their metabolites in humans was clarified.•The appropriateness of different human samples as biomonitoring matrices was discussed.•Suitable biomarkers in each type of biomonitoring matrix were evaluated.
Take-out food has become increasingly prevalent due to the fast pace of people's life. However, few study has been done on microplastics in take-out food. Contacting with disposable plastic ...containers, take-out food may be contaminated with microplastics. In the present study, abundance and characteristics of microplastics in total of 146 take-out food samples including solid food samples and beverage samples (bubble tea and coffee) were determined and identified. The mean abundance of microplastics in take-out food was 639 items kg−1, with the highest value in rice and the lowest value in coffee. Fragments shape, transparent color and sizes ≤ 500 μm were the main characteristics of microplastics in those food, and polyethylene was the main polymer type. Our results indicated that microplastics in take-out food was influenced by food categories and cooking methods, as well as food packaging materials. Approximately 170–638 items of microplastics may be consumed by people who order take-out food 1–2 times weekly.
•Microplastics (MPs) were found in various popular take-out food.•Polyethylene was the main polymer type of MPs in take-out food.•Cooking method, food containers and other factors will affect MPs in food.•∼170–638 items of MPs may be eaten if one orders those food 1–2 times weekly.
Liquid crystal monomers (LCMs) have been recognized as contaminants of emerging concerns. E-waste recycling sites and liquid crystal displays (LCDs) manufacturers are supposed to be critical sources. ...However, information regarding LCM contaminations in soils surrounding these sites are currently unavailable. In this study, soil samples were collected from two distinct areas in South China: e-waste recycling area (n = 36) and LCD manufacturer (n = 41), and 60 target LCMs (including 13 biphenyl and analogs (BAs), 10 cyanobiphenyl and analogs (CBAs), and 37 fluorinated biphenyl and analogs (FBAs)) were determined. The concentrations of LCMs in the soils from near the e-waste recycling area (0.32–18 ng/g, average: 4.2 ng/g) were higher than those surrounding the LCD manufacturer (ND – 7.2 ng/g, average: 1.5 ng/g). The compositional profiles of LCMs in soil samples from these two typical point sources were considerably different. The concentrations of FBAs exponentially decreased with distance from the e-waste recycling park, by >90 % within 2 km. The levels of BAs exhibited a similar exponential decrease with distance from the LCD manufacturer. The inventories of LCMs were estimated to be 21.0 kg in the e-waste recycling area and 10.8 kg in the LCD manufacturer area. Remarkably, the inventory of LCMs in soils from e-waste recycling area was one order of magnitude larger than that of hexabromocyclododecanes (HBCDs) in the same region, and 0.2 to 20 times the annual global emissions of LCMs from discarded LCD panels. More studies are required to elucidate the environmental occurrence, behavior, and fate of LCMs in multimedia environment surrounding typical point sources.
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•Higher concentrations of LCMs were observed in soils near e-waste recycling area than around the LCD manufacturer.•LCMs in soils from the two areas were characterized with different profiles.•Levels of LCMs exponentially decreased by 90 % within 2 km of the point sources.•Soil inventory of LCMs in e-waste recycling area was 0.2 to 20 times of the estimated global annual emissions.
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