Search

Graphical abstract Highlights • A recrystallization-annealing strategy was developed to fabricate alkalinized g-C 3 N 4 and TiO 2 composite. • The C N bond was dissociated while C OH was formed. • Synergetic effect of adsorption and photocatalysis enhanced the degradation of methylene blue. Abstract This work reports the fabrication of alkalinized g-C 3 N 4 and its composite with TiO 2 via recrystallization-annealing strategy. The increased surface basicity boosted the fast adsorptive removal of methylene blue (MB) while the cooperated TiO 2 enhanced the degradation of adsorbed MB via photocatalysis. The synthesized materials were characterized by XPS, SEM, TEM, PXRD, BET surface area, FT-IR, EDX and TG analyses. TiO 2 nanoparticles were uniformly distributed in the framework of alkalinized g-C 3 N 4 which increased the surface area of g-C 3 N 4. Na was incorporated into g-C 3 N 4 via thermal treatment, and the bond between C and N was dissociated while that between C OH was formed. The alkaline and negatively charged surface of g-C 3 N 4 upon Na addition established a strong electrostatic interaction adsorption scenario with MB leading to higher adsorption efficiency of TiO 2 /Na-g-C 3 N 4 (90%) than pristine g-C 3 N 4 (80%). MB removal efficiency was further intensified (from 90% to 100% within 120 min) upon the sequential operation of adsorption followed by photocatalytic degradation over TiO 2 /Na-g-C 3 N 4 under visible light irradiation. This study can be deemed of potential applications for the removal of MB and similar dyes on industrial level using the newly synthesized TiO 2 /Na-g-C 3 N 4 and synergistic adsorption-photocatalytic oxidation approach. [ABSTRACT FROM AUTHOR]

Copper foam with in-situ grown CuO nanowires (CuO NW/Cu foam) was used as an effective monolithic catalyst for the plasma-catalytic oxidation of toluene to CO 2 . The fabricated CuO nanowires were single crystalline with a length of ~ 5–50 μm and diameter of ~ 50–400 nm. It was found that toluene conversion was obviously enhanced and byproducts were significantly decreased with the use of CuO NW/Cu foam as a monolithic catalyst due to synergistic effects developed between plasma and catalytic effect. [ABSTRACT FROM AUTHOR]

Abstract: ZnO nanorods were synthesized on an InP substrate by pulsed laser deposition technique at 400 and 500°C. Low-temperature photoluminescence measurements were conducted to investigate the optical properties of the ZnO nanorods. It revealed that phosphorus-doped ZnO (ZnO:P) nanorods were formed by the diffusion of phosphorus from the InP substrate at 500°C, and four acceptor-bound exciton-related emission peaks emerged in the PL spectrum of ZnO:P nanorods. The effect of phosphorus-doping on the optical characteristics of the ZnO nanorods was investigated by excitation intensity and temperature dependent PL spectra. The binding energies of the acceptor were calculated to be ∼125meV. [Copyright &y& Elsevier]

In the context of top-color assisted technicolor (TC2) models, we calculate the contributions of the neutral top-pion πt0 to tγ and tz production via the processes ep→γc→tγ and ep→γc→tz at the HERA and THERA colliders. Our results show that the cross sections σtγ(s) and σtz(s) are very small at the HERA collider with √ of s=320 GeV. However, in most of the parameter space, σtγ(s) or σtz(s) is in the range of about 0.1–1 pb at the THERA collider with √ of s=1000 GeV. [Copyright &y& Elsevier]

Abstract: High-density well-aligned ZnO nanorod arrays were successfully fabricated on ZnO a seed-layer coated InP (001) substrate by using pulsed laser deposition (PLD) technique without metal catalyst. SEM image showed that uniformly distributed droplet-like ZnO seed-layer was formed on the InP wafer. Well-oriented ZnO nanorods were formed perpendicular to the seed-layer coated substrate and well-separated from each other. X-ray diffraction θ–2θ scanning measurements demonstrated that the ZnO nanorods exhibited a strong c-axis orientation with high crystalline quality. The photoluminescence (PL) spectrum measurement illuminated that the ZnO nanorods produced in this work had well optical quality. The well-aligned and separated ZnO nanorods fabricated by this comparatively simple technique shed light on further applications for nanodevices. [Copyright &y& Elsevier]

PbS quantum dots with nearly monodisperse size (∼3.8 nm) were successfully fabricated via a cation-exchange method, and were investigated by the z-scan technique with 532 nm laser radiation. The PbS quantum dots exhibited high optical nonlinearity with nonlinear absorption coefficient, nonlinear refractive index, and nonlinear susceptibility of 2.93 × 10−9 m/W, 1.12×10−9 esu, and 1.90 × 10-10 esu, respectively, and with optical limiting threshold value of 1.5 J/ c m 2 under experimental conditions. [ABSTRACT FROM AUTHOR]

Dioctyl phthalate (DOP) serves as a characteristic gas utilized in early electrical fire detection, its detection offers promising prospects for the prevention of electrical fires. In this study, we employed a modified photodeposition method to prepare Tin dioxide (SnO2) materials co‐modified with Au and oxygen vacancies. Subsequently, microelectromechanical systems (MEMS) gas sensor for DOP detection were fabricated, utilizing 0.5 %Au/SnO2−I as the sensing material. Characterization results reveal the presence of abundant oxygen vacancies in 0.5 %Au/SnO2−I. The synergistic interplay of Au and oxygen vacancies resulted in a remarkable response of 9.98 to 20 ppm of DOP at operational temperature of 250 °C. This represents a significant 96 % enhancement in comparison to the response value of 4.50 exhibited by pure SnO2 at 300 °C. Notably, this gas sensor boasts low power consumption and demonstrates a quick response in the detection of overheating polyvinyl chloride (PVC) cables under simulated conditions. [ABSTRACT FROM AUTHOR]

Coupling low-temperature plasma technology with catalysts can significantly enhance air purification efficiency and mitigate the generation of secondary pollutants. In this study, mesoporous γ -Al2O3 supported Mn–Ce–Co ternary oxides were introduced into a widely employed tubular dielectric barrier discharges (DBD) reactor for indoor air purification. The plasma-catalytic degradation of HCHO exhibited the following degradation efficiency order: Mn–Ce–Co/ γ -Al2O3 > Mn/ γ -Al2O3 > Mn–Ce/ γ -Al2O3 > Co/ γ -Al2O3 > γ -Al2O3 > Ce/ γ -Al2O3 > Plasma. When compared to plasma treatment alone, the catalyst resulted in a remarkable 1.8-fold enhancement under conditions of 3.0 kV, 2 5 ∘ C, 60% RH. Additionally, the concentrations of the by-products O3 and NO x were significantly reduced by 88.2% and 93.3%, respectively. The synergistic interaction between Mn, Ce and Co oxides facilitated the formation and transportation of surface-reactive oxygen species, thereby contributing to the thorough oxidation of HCHO and organic intermediates during the plasma-catalytic process. Moreover, the high specific surface area offered by mesoporous materials enhanced the adsorption and catalytic activity towards HCHO. The introduction of mesoporous γ-Al2O3 supported Mn–Ce–Co ternary oxides into a tubular dielectric barrier discharges (DBD) reactor significantly improved the performance on indoor air purification. The HCHO removal efficiency was enhanced 1.8-fold at 3.0 kV, 25∘C, 60% RH, while the concentrations of the by-products O3 and NOx were significantly reduced by 88.2% and 93.3%, respectively. [ABSTRACT FROM AUTHOR]

The development of a selective and fast response gas sensor for dioctyl phthalate (DOP) has been attracting considerable attention for the early warning of electrical fires. In this study, photodeposition was applied to fabricate highly dispersed Pd/SnO2 with abundant defects. The obtained 5%Pd/SnO2 has more Sn2+ species and oxygen vacancies than SnO2, which may be due to the reduction of photogenerated electrons. 5%Pd/SnO2 exhibited the best comprehensive performance in response value and response and recovery time for DOP sensing among different Pd loadings. The response to 5 ppm of DOP is 3.58 at 240 °C, which is much higher than 1.03 for SnO2, due to the abundant oxygen vacancies and Sn2+ defects of the material. Besides, the material exhibited good selectivity, stability, and a linear response to different concentrations of DOP. The 5%Pd/SnO2 sensor also responded much faster than conventional smoke detectors for the overheated PVC cable. [ABSTRACT FROM AUTHOR]

This work reports a facile calcination-soak approach for the large-scale growth of Co-Mn composite shell over the cores of copper mesh and foam resulting in Co-Mn@CuO nanowires. In the synthesis of Co-Mn@CuO core/shell structure, CuO nanowires were first formed on copper mesh through a facile calcination, followed by Co-Mn compounds (MnO 2 and CoOOH or Co(OH) 3 ) soaking to form a coat on the outer surface of CuO nanowires attributed to the redox reaction between MnO 4 − and Co 2+ , which were calcined in air to get the final Co-Mn oxide. The thickness of the Co-Mn oxide shell over CuO nanowire could be easily tuned by soaking duration. The prepared Co-Mn@CuO nanowires were applied as monolithic catalysts in plasma-catalytic oxidation of toluene and decomposition of ozone. The catalytic performance was enhanced to ~88% at 1.0 A and ~95% at 1.5 A with the filling of Co-Mn@CuO core/shell structure as monolith catalyst, which could be attributed to the synergistic effect of plasma and catalytic effect. Using Co-Mn@CuO, 95% ozone conversion was achieved at room temperature credited to the presence of mixed-valent manganese ions in the catalyst. [ABSTRACT FROM AUTHOR]

Vertical Radial Plume Mapping (VRPM) is a method for measuring fluxes of fugitive surface source gases, lacking sufficient temporal sequence information as it inversely calculates fluxes only based on the current cycle's measurements. We propose an improved VRPM flux inversion model, incorporating Weighted Iterative Average (WIA) corrected Path-Integrated Concentration (PIC) and Adaptive Weighted Sum of Squared Errors (AWSSE). Compared to the original VRPM, our model introduces historical measurement PICs and reconstructed PICs. Using the Bayesian Optimization Gaussian Processes (BO-GP), we derive optimal weight factor for the hyperparameter of the WIA component in the model. Validation on simulated data highlights the superior flux inversion capability of the WIA-AWSSE-VRPM model across diverse surface sources, efficiently leveraging historical data. The improved VRPM method achieves a significant 9.65% reduction in root mean square error (RMSE) within consistent source sets and decreases RMSE from 1.6979 to 0.1513 across varied sources, underscoring its effectiveness in accurately measuring emissions from fugitive sources. Finally, we apply the model to characterize gas emissions in field experiments. • Novel VRPM Flux Inversion Model with WIA and AWSSE Enhancements. • Optimal Hyperparameter Determination Using BO-GP for WIA Component. • Simulation Validation Demonstrates Robust Accuracy and Generalization. • Comparative Statistical Evaluation Highlights Superior Performance of the VRPM Model. [ABSTRACT FROM AUTHOR]

Abstract: Well-aligned ZnO nanocone arrays (NCAs) were prepared on fluorine doped tin oxide (FTO) substrates using highly ordered ZnO nanorod arrays (NRAs) as templates to guide the growth via a hydrothermal method. In contrast, only disordered ZnO nanocones on FTO were obtained in the absence of the highly ordered ZnO nanorod templates. The well-aligned ZnO nanocone arrays were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–visible absorption, and photoluminescence (PL) spectroscopies. It was found that the highly ordered ZnO NRAs pre-formed on FTO played a critical role in dictating the further growth of the well-aligned ZnO NCAs from them. Significantly, strong light-trapping effect was revealed for the well-aligned ZnO NCAs, which may find important applications in, e.g., photovoltaics. [Copyright &y& Elsevier]

Antimony selenide (Sb2Se3) is an emerging photovoltaic material. We demonstrate that PbI2 is an effective p-type dopant for Sb2Se3. The Sb2Se3 film was doped by PbI2 by thermal diffusion. Both the hole concentration and conductivity are dramatically increased by doping. We fabricated the Sb2Se3 solar cell using C60 as an electron transport layer by vacuum thermal evaporation. By PbI2 doping, the open-circuit voltage (Voc) is increased from 0.32 to 0.38 V, and the power conversion efficiency is improved from 2.87% to 4.43%. This work provides an effective p-type dopant for Sb2Se3. [ABSTRACT FROM AUTHOR]

• Targeted activation of polycyclic tetramate macrolactams (PTMs) using a combined strategy. • One new PTM (1) along with three enol-type tetramic acid tautomers (2 – 4) were isolated. • Compound 1 exhibited notable growth inhibition against plant pathogenic fungi. • Compounds 1 – 4 exhibited moderate cytotoxicity against the human cancer cell lines. With a combined strategy of bioinformatics analysis, gene manipulation coupled with variation of growth conditions, the targeted activation of polycyclic tetramate macrolactams (PTMs) in the deepsea-derived Streptomyces somaliensis SCSIO ZH66 was conducted, which afforded a new (1) PTM, named somamycin A, along with three enol-type tetramic acid tautomers (2 – 4 , somamycins B–D) of 10- epi -hydroxymaltophilin, 10- epi -maltophilin and 10- epi -HSAF, respectively. The structures of compounds 1 – 4 were elucidated by extensive spectroscopic analyses together with ECD calculations. Compound 1 exhibited notable growth inhibition against plant pathogenic fungi Fusarium oxysporum MHKW and Alternaria brassicae BCHB with the MIC values of 1.6 and 3.1 μg/mL, respectively, which were more potent than those of the positive control nystatin; and compounds 3 and 4 displayed moderate antifungal activities. Moreover, compounds 1 – 4 exhibited moderate cytotoxicity against the human cancer cell lines of HCT116 and K562. [ABSTRACT FROM AUTHOR]

Abstract: ZnO thin films were prepared on quartz glass, Si (100), and sapphire (001) substrates by a chemical vapour transport (CVT) technique. During the growing processes, the source and substrate temperatures were maintained at 1000 °C and 600 °C, respectively. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements showed that the crystalline qualities of ZnO thin films were sensitively dependent on substrates. ZnO thin film deposited on sapphire substrate exhibited the best morphology with the largest crystallite size of more than 20 μm. Meanwhile, the XRD patterns showed that ZnO thin film deposited on sapphire substrate was strongly c-axis preferred-oriented with high crystalline quality. The optical properties of ZnO thin films were investigated by photoluminescence (PL) spectroscopy at room temperature (RT). The results suggested that the optical properties of ZnO thin films were highly influenced by their crystalline qualities and surface morphologies. [Copyright &y& Elsevier]

• We propose using Radial Basis Function (RBF) interpolation to increase the number of data pairs in Vertical Radial Plume Mapping (VRPM), a mass balance method used to quantify area source emissions. • Our results show that RBF interpolation significantly improves the accuracy of flux inversion, with reduced mean absolute error (MAE) and root mean square error (RMSE), especially using the Gaussian RBF interpolation method. • The average flux calculated after performing RBF interpolation is closer to the real result, reflecting the average emission level more accurately. • Our proposed method can be used to improve the accuracy of VRPM without changing the original measurement settings, providing an innovative and valuable approach for accurately quantifying fugitive gas emissions from non-point sources. The Vertical Radial Plume Mapping (VRPM) method proposed by the U.S. EPA in Other Test Method 10 (OTM-10) is widely used to measure nonpoint source emissions. However, the accuracy of the VRPM is affected by the large number of parameters relative to the measurement data and the presence of measurement noise. To improve the accuracy of flux estimation, we propose to apply evenly spaced radial basis function (RBF) interpolation to the measurement data before using the VRPM. The experiment was tested and validated under various measurement configurations. The results indicate that RBF interpolation techniques, especially Gaussian RBF (GSRBF) interpolation, reduce the mean absolute error and root mean square error of flux estimation, leading to improved flux estimation accuracy. The mean emission rate calculated after RBF interpolation is closer to the true value, indicating that this interpolation technique helps to reflect more accurately the average emission level over time. Even in the most challenging validation set, the percentage error of mean flux decreased by 3.8% after interpolation. The proposed method can be a simple and measurement-cost-effective way to improve the accuracy of VRPM measurements. [ABSTRACT FROM AUTHOR]

• Uniform alloyed Au-Pt nanoparticles with 2–3 nm were loaded on TiO2 via photodeposition. • The turnover frequency of Au-Pt/TiO2 is 3.4 times of that of Pt/TiO 2. • Au-Pt alloy structure is beneficial for the adsorption and dissociation of oxygen. • Au-Pt alloy promotes the transformation of dioxymethylene species to formate species. [Display omitted] Catalytic oxidation has been considered as one of the most promising strategies for the removal of indoor HCHO which causes multiple health problems. Alloyed Au-Pt showed potential for catalytic oxidation reactions, but the reports on HCHO oxidation are limited. In addition,understanding on the catalytic mechanism is lacking. In this work, a sodium citrate assistant photodeposition process was developed to fabricate highly dispersed dual Au-Pt alloy with 2–3 nm on the surface of TiO 2. The turnover frequency of Au-Pt/TiO 2 (68.6 h-1) is much higher than that of Pt/TiO 2 (19.9 h-1). This enhancement was also confirmed on different TiO 2 supports and with different Pt loading. Based on the experimental and density functional theory calculations, it was found that the alloyed Au-Pt has more metallic Pt and is beneficial for the adsorption and dissociation of oxygen. Therefore, the rapid conversion of dioxymethylene species to formate species, with reduced reaction barrier, promotes the performance in catalytic oxidation of HCHO. [ABSTRACT FROM AUTHOR]

• DL combined with PEMS and OBD for building prediction model of vehicle emissions. • An innovative attention encoding structure was proposed to accelerate convergence. • An automatic elimination method for the outliers in the PEMS data was proposed. • An early warning system of high vehicle emissions was proposed. • A model that can be trained with lab tests to predict on-road results was proposed. Portable emission measurement system (PEMS) testing, which is the most accurate measurement method for vehicle emissions, has been included into the regulations of vehicle emission standards in various countries. However, PEMS is expensive, and in the long-term measurement process, the monitoring data will exhibit outliers, which is a drift phenomenon. In addition, as a measurement method, it cannot prevent the occurrence of high vehicle emissions. To solve the above problem, this study proposes a parallel attention-based long short-term memory (PA-LSTM) for building an emission prediction model using PEMS and on board diagnostics (OBD). According to the characteristics of the real vehicle road test and bench test data, the PA-LSTM model adopts a parallel spatial attention coding mechanism, combined with a temporal attention decoding mechanism. Qualitative and quantitative experimental results show that the PA-LSTM model can achieve a more accurate prediction of vehicle emissions compared with other popular models, and the proposed model can eliminate outliers and restrain the offset of the zero levels in the PEMS data. The most significant thing is that the PA-LSTM model can foresee about the possible high vehicle emissions in the future and provide timely feed-back to the emission control system of the vehicle engine, so as to make corresponding control measurements in time and avoid the occurrence of high emissions. [ABSTRACT FROM AUTHOR]

Abstract: A p-ZnO:N/n-GaN:Si structure heterojunction light-emitting diode (LED) is fabricated on c-plane sapphire by full metal organic chemical vapor deposition (MOCVD) technique. The p-type layer with hole concentration of 8.94×1016 cm−3 is composed of nitrogen-doped ZnO using NH3 as the doping source with subsequent annealing in N2O plasma ambient. Silicon-doped GaN film with electron concentration of 1.15×1018 cm−3 is used as the n-type layer. Desirable rectifying behavior is observed from the current–voltage (I–V) curve of the device. The forward turn on voltage is about 4V and the reverse breakdown voltage is more than 7V. A distinct ultraviolet (UV) electroluminescence (EL) with a dominant emission peak centered at 390nm is detected at room temperature from the heterojunction structure under forward bias conditions. The origins of the EL emissions are discussed in comparison with the photoluminescence (PL) spectra. [Copyright &y& Elsevier]

Abstract: Well-aligned ZnO nanorod arrays were synthesized by low-temperature wet chemical bath deposition (CBD) method on Si substrate under different conditions. Results illustrated that dense ZnO nanorods with hexagonal wurtzite structure were vertically well-aligned and uniformly distributed on the substrate. The effects of precursor concentration, growth temperature and time on nanorods morphology were investigated systematically. The mechanism for the effect of preparation parameters was elucidated based on the chemical process of CBD and basic nucleation theory. It is demonstrated that the controllable growth of well-aligned ZnO nanorods can be realized by readily adjusting the preparation parameters. Strong near-band edge ultraviolet (UV) emission were observed in room temperature photoluminescence (PL) spectra for the samples prepared under optimized parameters, yet the usually observed defect related deep level emissions were nearly undetectable, indicating high optical quality ZnO nanorod arrays could be achieved via this easy process chemical approach at low temperature. [Copyright &y& Elsevier]

Optical remote sensing systems (RSSs) for monitoring vehicle emissions can be installed on any road and provide non-contact on-road measurements, that allow law enforcement departments to monitor emissions of a large number of on-road vehicles. Although many studies in different research fields have been performed using RSSs, there has been little research on the automatic recognition of on-road high-emitting vehicles. In general, high-emitting vehicles and low-emitting vehicles are classified by fixed emission concentration cut-points, that lack a strict scientific basis, and the actual cut-points are sensitive to environmental factors, such as wind speed and direction, outdoor temperature, relative humidity, atmospheric pressure, and so on. Besides this issue, single instantaneous monitoring results from RSSs are easily affected by systematic and random errors, leading to unreliable results. This paper proposes a method to solve the above problems. The automatic and fast-recognition method for on-road high-emitting vehicles (AFR-OHV) is the first application of machine learning, combined with big data analysis for remote sensing monitoring of on-road high-emitting vehicles. The method constructs adaptively updates a clustering database using real-time collections of emission datasets from an RSS. Then, new vehicles, that pass through the RSS, are recognized rapidly by the nearest neighbor classifier, which is guided by a real-time updated clustering database. Experimental results, based on real data, including the Davies-Bouldin Index (DBI) and Dunn Validity Index (DVI), show that AFR-OHV provides faster convergence speed and better performance. Furthermore, it is not easily disturbed by outliers. Our classifier obtains high scores for Precision (PRE), Recall (REC), the Receiver Operator Characteristic (ROC), and the Area Under the Curve (AUC). The rates of different classifications of excessive emissions and self-adaptive cut-points are calculated automatically in order to provide references for law enforcement departments to establish evaluation criterion for on-road high-emitting vehicles, detected by the RSS. [ABSTRACT FROM AUTHOR]