Search

High performance hydrophobic Pt/SiO2 as an adsorbent buffer catalyst for toluene removal.

Automatic epileptic seizure detection technologies for clinical diagnosis mainly rely on electroencephalogram (EEG) recordings, which are immensely useful tools for epileptic location and identification. Currently, traditional seizure detection methods based only on single-view features have great limitations for the typical dynamic and nonlinear EEG signals. An objective of this paper is to investigate the effect of multiview feature selection and multilevel spectral analysis methods on the identification of the EEG signals for seizure detection. Here, multiview features are extracted from time domain, frequency domain, and information theory to collect adequate information of EEG signals. And a feature selection algorithm based on particle swarm optimization (PSO) is proposed for automatic seizure detection. Moreover, due to the different frequency components of the EEG signals, they are divided into four kinds of brain waves for multilevel spectral analysis. The effect of these four rhythm waves on seizure detection is compared. Three well-known classifiers are employed to classify EEG signals concerning seizure or nonseizure events. The result shows that the average accuracy, specificity, and sensitivity of classification with the CHB-MIT database are 98.14%, 98.64%, and 96.79%, respectively. The application of the PSO-based feature selection method for automatic seizure detection improves accuracy by 5.99% with the SVM classifier. Compared with the state-of-the-art methods, the proposed method has superior competence with high performance for automatic seizure detection. It is further shown that the feature selection method is an indispensable step in seizure detection. With PSO-based feature selection and multilevel spectral analysis, the θ wave in the frequency range of 4-7 Hz shows better performance in the identification of EEG signals and is more suitable for the proposed method. The PSO-based feature selection algorithm for automatic seizure detection can be a useful assistant tool for clinical diagnosis.

The distinction of dechlorination over activation sites with the aid of Ru/TiO2 catalysts derived from MOFs.

The millimeter-wave (mmWave) and massive multiple-input multiple-output (MIMO) wireless communication technologies provide vital means to resolve many technical challenges of the fifth-generation (5G) or beyond 5G (B5G) network. Analyzing the measured datasets extracted from the channel measurements can provide insight into the characteristics of radio channels in different scenarios. Therefore, mmWave massive MIMO channel measurements, simulation, and modeling are carried out in the high-speed railway waiting hall environments at 28 GHz. The multipath components (MPCs) parameters are estimated for line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios based on the space-alternating generalized expectation-maximization (SAGE) algorithm. Delay spread (DS), azimuth angle of arrival (AAoA), and elevation angle of arrival (EAoA) are analyzed. And they are processed by using the K-mean algorithm. In addition, propagation characteristics are simulated based on the improved ray tracing method of shooting and bouncing ray tracing/image (SBR/IM). The correctness of the improved ray tracing method is verified by comparing the measured results with the simulated results. The large-scale path loss (PL) is characterized based on close-in (CI) free-space reference distance model and the floating-intercept (FI) path loss model. Furthermore, statistical distributions for root-mean-square delay spread (RMS DS) are investigated. The Gaussian distribution best fits the measured data of RMS delay spread. Finally, multipath clustering is identified using the multipath component distance (MCD). The analysis of these results from mmWave massive MIMO channel measurements and simulation may be instructive for the deployment of the 5G or B5G wireless communications systems at 28 GHz.

As a significant source of indoor and outdoor pollutants, cooking fumes have a great impact on air quality and human health. However, the limited identification and quantification techniques hinder the comprehensive understanding of the complex cooking fumes with wide volatility and polarity. Herein we applied thermal desorption comprehensive two-dimensional gas chromatography-mass spectrometer (TD-GCxGC-MS) for synchronous analysis of gaseous and particulate organics emitted from cooking fumes. With a systematic 4-step qualitative procedure and precise quantitative and semi-quantitative method, 170 and 352 compounds from C2 (acetic acids) – C30 (squalene) occupying 95 % and 90 % of the total ion current for gaseous and particulate samples were identified and quantified. For most compounds, the correlation coefficient (R2) is >0.9, and the relative standard deviation (RSD, n=5) of three concentration levels (low, medium, high) is within 10 %. For the semi-quantification, the total uncertainty is ~27 %. Compared with gas chromatography-mass spectrometer (GC-MS) and proton transfer time-of-flight mass spectrometer (PTR-ToF-MS), TD-GCxGC-MS detects more compounds, especially the diagnostic tracers related to cooking oil and matierial, and additives added during cooking and secondary products transformed from carbonyls and acids. Hence, TD-GCxGC-MS provides plenty of perspectives to analyze the primary emission and secondary formation from cooking at a molecular level.

To elucidate the molecular chemical compositions, volatility-polarity distributions, as well as influencing factors of Chinese cooking emissions, a comprehensive cooking emission experiment was conducted. Semi-volatile and intermediate volatility organic compounds (S/IVOCs) from cooking fumes were analyzed by a thermal desorption comprehensive two-dimensional gas chromatography coupled with quadrupole mass spectrometer (TD-GC×GC-qMS). Emissions from four typical Chinese dishes, i.e., fried chicken, Kung Pao chicken, pan-fried tofu, and stir-fried cabbage were investigated to illustrate the impact of cooking style and material. Fumes of chicken fried with corn, peanut, soybean, and sunflower oils were investigated to demonstrate the influence of cooking oil. A total of 201 chemicals were quantified. Dishes cooked by stir-frying or deep-frying cooking styles emit much more pollutants than relatively mild cooking methods. Aromatics and oxygenated compounds were extensively detected among meat-related cooking fumes, while a vegetable-related profile was observed in the emissions of stir-fried cabbage. The volatility-polarity distributions of the four dish emissions were quite similar, yet the distributions diverged when different types of oils were utilized. Ozone formation potential (OFP) was dominated by chemicals in the VOC range. 10.2 % - 32.0 % of the SOA estimation could be explained by S/IVOCs. Pixel-based partial least squares-discriminant analysis (PLS-DA) and multiway principal component analysis (MPCA) were utilized for sample classification and key components identification. The results indicated that the oil factor explained more variance of chemical compositions than the cooking style factor. MPCA results emphasize the importance of the unsaturated fatty acid-alkadienal-volatile products mechanism (oil autooxidation) accelerated by the cooking and heating procedure.

Cooking oil fumes (COFs) represent a major indoor environmental pollutant and exhibit potent mutagenic or carcinogenic health effects caused by containing various heterocyclic aromatic amines (HAAs) and long-chain aldehydes. Despite some evaluation of the relationship between cumulative exposure to COFs and lung cancer, mainly focused on high concentration exposure to cancer cells, and cell damage of HAAs and aldehydes with low dose exposure to healthy cells has been unadequately investigated. Herein, we have firstly scrutinized the toxicity of these three typical compounds of HAAs and aldehyde emission from COFs, which includes heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 3,8-dimethylammidazo[4,5-f]quinoxalin-2-amine (MeIQx) and trans, trans-2,4-decadienal (TDA)) to both in vitro and in vivo. In vitro experiments revealed that the PhIP, MeIQx and TDA aerosol particles had negligible toxicity to cancer cells (A549 and HepG-2) but strong cytotoxicity to normal healthy cells (HelF and L02) under 0.5-4 µg/mL low dose exposure based on the reactive oxygen species (ROS) mechanism. Furthermore, the in vivo data demonstrate that PhIP causes significant damage to the lung and liver after monitoring mice after 30 days of exposure to a larger amount of PhIP. These results indicate direct proof of COFs damage even at low exposure to HAAs and aldehydes.

Human body area communication has been widely used in the fifth-generation (5G) wireless communication systems. Human bodies bring complexity for channel modeling, and directly affect the performance of the wireless communication systems. In this letter, channel measurements, simulations, and modeling are carried out in a curved tunnel scenario with several human bodies. A human body is modeled by two typical methods to analyze the influence of the channel modeling on the accuracy based on measurements and the innovative ray-tracing method. The comparison of path loss models is provided and a novel generalized path loss model in terms of the curved tunnel scenario is proposed. Multipath dispersion properties are characterized and corresponding statistical distributions are also investigated. Furthermore, the multipath component parameters including angular characteristics of angle of arrival and power of multipath components are analyzed. Multipath clustering is identified using the multipath component distance.

A series of nanocrystalline copper–manganese oxides (denoted as Cu3−xMnx, x = 0, 1, 1.5, 2, 2.5, 3, where x means the molar ratio of Cu and Mn) were successfully prepared by a facile citric acid sol–gel method. The combination of Cu2+ and Mn3+ is intensified and enhanced interface effects generated, which is beneficial for the catalytic oxidation of benzene. A series of analyses, such as X-Ray Diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), and hydrogen temperature programmed reduction (H2-TPR), were employed to further investigate the structural properties of the catalysts. An optimal Mn/Cu ratio of 2 forms CuMn2O4 spinels. CuMn2 with CuMn2O4 spinel structure presents a larger specific surface area, smaller pore diameter as well as more lattice oxygen species, exhibiting remarkable activity and stability for the catalytic oxidation of benzene. On account of these factors, CuMn2 possesses better low temperature reducibility and shows the best catalytic performance with 90% benzene conversion at 186 °C. The enhanced catalytic activity of CuMn2 is attributed to the stabilization of CuMn2O4 active phases and the intensive synergistic effect between Cu–Mn oxides. To prove the effect of CuMn2O4 spinel structure on catalytic performance, a CuO/Mn2O3 mixed catalyst (molar ratio 1 : 1) was prepared and applied to benzene oxidation (T90% = 198 °C), which indicates that the spinel structure has an encouraging effect on benzene catalysis. The catalytic properties of single copper oxide and manganese trioxide were also tested, the results show that CuMn2O4 has a crucial role in facilitating electronic transmission and mobility of the lattice oxygen.

In situ designed monolithic catalysts possess a bright prospect in practical industrial catalytic applications owing to their strong anchoring force and lower pressure drop. In this study, a series of NiCo2O4 nickel foam-based monolithic catalysts were successfully prepared via an in situ electro-deposition strategy. The active phase was strongly and vertically anchored on a nickel foam, leading to a catalyst with a stable structure, abundant surface areas and an excellent electronic transmission capacity. Moreover, the as-prepared catalysts exhibited abundant structural defects, which can be attributed to the violent reaction rate. All the samples assuredly possessed excellent benzene oxidation performance, and the CoNi-NF-2 : 1 sample exhibited a superior activity, oxidizing about 90% of benzene (T90) at 198 °C under a gaseous hourly space velocity (GHSV) of 6000 h−1. A conclusion can be rationally drawn that the superior catalytic performance and the stability of the catalysts are primarily attributable to the strong anchoring force, rich oxygen vacancies, and the higher Co3+/Co2+ ratio according to the relevant characterizations. Furthermore, the benzene combustion mechanism was summarized by adequately studying the above conclusions and previous studies. This work indicates a promising strategy to design highly active monolithic catalysts with abundant defects, which potentially pave the way for the thorough removal of industrial benzene.

In the present work, we conducted experiments of secondary organic aerosol (SOA) formation from urban cooking and vehicular sources to characterize the mass spectral features of primary organic aerosol (POA) and SOA using an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Our results showed that the cooking styles have a greater impact on aged COA (cooking organic aerosol) mass spectra than oxidation conditions. However, the oxidation conditions affect the aged HOA (hydrocarbon-like OA) spectra more significantly than vehicle operating conditions. In our study, we use mass spectra similarity analysis and positive matrix factorization (PMF) analysis to establish the POA and SOA mass spectra of these two sources. These mass spectra are used as source constraints in a multilinear engine (ME-2) model to apportion the OA (organic aerosol) sources in the atmosphere. Compared with the traditional ambient PMF results, the improved ME-2 model can better quantify the contribution of POA and SOA from cooking and vehicular sources. Our work, for the first time, establishes the vehicle and cooking SOA source profiles, and can be further used in the OA source apportionment in the ambient atmosphere.

Monolithic catalysts with high catalytic activity bring about increasing interest in practical environmental purification field for volatile organic compounds (VOCs) degradation with low pressure drops. Monolithic CoMnAlO catalysts with varied Co/Mn molar ratio derived from in situ supported layered double hydroxides (LDH) film are prepared through ammonia hydrothermal growing on Al substrate following calcinations. The textural properties for CoMnAlO catalysts with low temperature reducibility, surface element species are controlled by tuning the initial Co/Mn molar ratio verified through H2-TPR and XPS spectra. CoMn2AlO film sample shows best activity with the temperature for 90% benzene decomposition (T90) around 238 °C with space velocity 300,000 ml gcat−1 h−1. The reaction rate of CoMn2AlO film is about 1.32 mmol gcat−1 h−1 at 260 °C with T99, which is nearly two times to that of Co3AlO film catalyst with 0.73 mmol gcat−1 h−1, because of the higher Mn4+/Mn3+ and Co3+/Co2+ atomic ratios and reducibility inducing by the synergistic effect of Co and Mn. The value is five times higher than CoMn2AlO powder catalyst with 0.26 mmol gcat−1 h−1, which is due to the great exposure active sites.

High reactivity and sintering resistance are key factors to design outstanding CH4 oxidation noble metal-based supported catalysts. Herein, we prepared and screened 0.5 wt% Pd/Al2O3 (among 0.3–3 wt% Pd loading) samples prepared by wet impregnation with very high CH4 catalytic activity. The hydrophobic modification of γ-Al2O3 support by triethoxyoctylsilane (TEOOS) exhibits further enhanced activity for CH4 oxidation, ca. T90 decrease from 375 °C to 350 °C with enhanced concentration of surface Pd0 sites. Besides, after Al2O3 protection layer deposition over the 0.5 wt% Pd/Al2O3 by atomic layer deposition (ALD), distinct higher temperature stability due to reduced agglomeration was demonstrated.

Herein, we reported the synthesis of well-defined Co3O4 nanoarrays (NAs) supported on a monolithic three-dimensional macroporous nickel (Ni) foam substrate for use in high-efficiency CO oxidation. The monolithic Co3O4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time, solvent polarity and deposition agent, these Co3O4 NAs catalysts exhibited various novel morphologies (single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co3O4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity (GHSV) 10,000 hr− 1 and 150°C with long-term stability. Compared with the other Co3O4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites (Co3 +/Co2 + = 1.26).

Zinc cadmium sulfide solid solution (ZnxCd1−xS) photocatalysts have received significant attention in energy and environmental applications because of their wide and strong visible light absorption range. However, the high photogenerated electron–hole pair recombination rate is an innate problem for their application. In this study, Cu2S/Zn0.67Cd0.33S (CZCS) nanosheet heterojunctions were fabricated by the in situ topotactic hydrothermal transformation of CuZnCdAl layered double hydroxide (LDH) precursors. Structural and morphological characterization indicated that the CZCS nanosheets were 2D/2D atomic-level in-plane heterojunctions with matched crystalline orientation because of their intergrowth structure originating from the topotactic sulfurization of CuZnCdAl LDH precursors. This in-plane intergrowth structure enhanced the separation of photogenerated electron–hole pairs based on a direct Z-scheme mechanism, which, in addition to providing a wide light absorption range and appropriate flat band potential, endowed excellent photocatalytic hydrogen production at the rate of 15.27 mmol h−1 g−1 (about 3.82 times that of pure Zn0.67Cd0.33S) from water splitting under visible light irradiation without the additive Pt cocatalysts. This photocatalyst with a superior photocatalytic activity and cycling stability can serve as a hopeful candidate for applications in the energy and environment field.

CuO–CeO2 nanocatalysts with different amounts of Mn dopping (Mn/Cu molar ratios of 0.5 : 5, 1 : 5 and 1.5 : 5) were synthesized by flame spray pyrolysis (FSP) method and tested in the catalytic oxidation of CO. The physicochemical properties of the synthesised samples were characterized systematically, including using X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), oxygen-temperature programmed desorption (O2-TPD), hydrogen-temperature programmed reduction (H2-TPR) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The results showed that the 1Mn–Cu–Ce sample (Mn/Cu molar ratio of 1 : 5) exhibited superior catalytic activity for CO oxidation, with the temperature of 90% CO oxidation at 131 °C at a high space velocity (SV = 60 000 mL g−1 h−1), which was 56 °C lower than that of the Cu–Ce sample. In addition, the 1Mn–Cu–Ce sample displays excellent stability with prolonged time on CO stream and the resistance to water vapor. The significantly enhanced activity was correlated with strong synergetic effect, leading to fine textual properties, abundant chemically adsorbed oxygen and high lattice oxygen mobility, which further induced more Cu+ species and less formation of carbon intermediates during the CO oxidation process detected by in situ DRIFTS analysis. This work will provide in-depth understanding of the synergetic effect on CO oxidation performances over Mn doped CuO–CeO2 composite catalysts through FSP method.

In the present work, we conducted experiments of secondary organic aerosol (SOA) formation from urban lifestyle sources (cooking and vehicle) to characterize the mass spectral features of primary organic aerosol (POA) and SOA using an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Our results showed that the cooking styles have greater impact on aged COA mass spectra than oxidation condition. However, the oxidation conditions affect the aged HOA spectra more significantly than vehicle operation conditions. In our study, we use mass spectra similarity analysis and positive matrix factorization (PMF) analysis to establish the POA and SOA mass spectra of these two typical lifestyle sources. These mass spectra are used as source constraints in a multilinear engine (ME-2) model to apportion the OA sources in the atmosphere. Comparing with the traditional ambient PMF results, the improved ME-2 model can better quantify the contribution of POA and SOA from life-style sources. Our work, for the first time, establishes the vehicle and cooking SOA source profiles, and can be further used in the OA source apportionment in the ambient atmosphere.

Both vehicle exhaust and cooking emission are closely related to the daily life of city dwellers, which are considered as major sources of urban secondary organic aerosol (SOA). Here, we defined the SOA derived from vehicle exhaust and cooking emission as Urban Lifestyle SOA, and simulated their formation using a Gothenburg potential aerosol mass reactor (Go: PAM). After samples had been aged under 0.3–5.5 days of equivalent photochemical age, these two urban lifestyle SOA showed markedly distinct features in SOA mass growth potentials, oxidation pathways and mass spectra. The SOA / POA mass ratios of vehicle groups (107) were 44 times larger than those of cooking groups (2.38) at about 2 days of equivalent photochemical age. It reveals that organics from vehicle may undergo the alcohol/peroxide and carboxylic acid oxidation pathway to produce abundant less/more oxidized oxygenated OA (LO-OOA and MO-OOA), and only a few primary hydrocarbon-like organic aerosol (HOA) remains unaged. In contrast, organics from cooking may undergo the alcohol/peroxide oxidation pathway to produce moderate LO-OOA, and comparable primary cooking organic aerosol (COA) remains unaged. Our findings provide an insight into atmospheric contributions and chemical evolutions for urban lifestyle SOA, which would greatly influence the air quality and health risk assessments in urban areas.

In this paper, the millimeter-wave propagation characteristics at 60 GHz for fifth generation (5G) wireless communication systems in corridor environment are studied based on the method of shooting and bounding ray tracing/image (SBR/IM). Firstly, the correctness of the simulation is verified by comparing with the measured data. In addition, the simulation of line-of-sight (LOS) and non-line-of-sight (NLOS) environment is carried out. The propagation characteristics, including path loss and power angle profile are discussed.

Based on the Shooting and Bouncing Ray Tracing Method / Image Method (SBR / Image method), the influence of cross-polarization on the characteristics of 28 GHz millimeter-wave channels (path loss, delay spread, direction of arrival) is studied. The simulated results of the co-polarization (V-V) are in good agreement with the measured results of the original literature. Furthermore, the influence of cross-polarization on channel characteristics is studied, which provides a theoretical basis for the successful deployment of 5G mobile communication networks.

Wireless communication at millimeter-wave bands has been a research hot spot in the latest years. In this paper, a typical urban microcell environment is simulated at 73 GHz in line-of-sight scenarios (LoS) and non-line-of-sight (NLoS) scenarios by the SBR method. First, the validity of the SBR method is verified by comparing the measurement and simulation results of path loss. Next, the propagation characteristics in LoS and NLoS scenarios are studied, such as power angle profiles and power delay angle profiles. Some characteristics of the millimeter-wave channel are revealed from these analyses.

The cellular uptake of narrowly dispersed LDH {[Mg3Al(OH) 8](CO3)0.5} nanoparticles into the Mouse Motor Neuron (NSC 34) cell line has been studied. The effect of LDH concentration and incubation time on the cellular uptake was investigated using fluorescein isothiocyanate (FITC) labelled LDH nanoparticles. We observed that cellular uptake increases with the increased LDHs concentration and incubation time. Confocal laser microscopy and transmission electron microscopy reveal that 20 nm LDHs nanoparticles intrude into the cytoplasm and then enrich in the cellular nucleus, while nanoparticles greater than 20 nm only locate in the cytoplasm. The 20 nm sized LDHs nanoparticles display similar uptake to both the cytoplasm and nucleus, and show little cytotoxicity with no significant decrease in NSC 34 cell proliferation and viability below 200 μg ml-1. DNA modified 20 nm LDH nanoparticles are successful in transfection of the pEGFP-N1 DNA plasmid to NSC 34 cells. © 2013 The Royal Society of Chemistry.

A series of V2O5/TiO2 catalysts with high vanadium loading (6.0 ∼ 43.9 wt%) were prepared by wet impregnation over metal–organic framework (MOF) MIL-125(Ti) support following calcination, and were tested for catalytic combustion of 100 ppm chlorobenzene. Taking advantage of MIL-125(Ti) with high surface area, copious catalytically active VOx species generated in the case of high vanadium loading, among which 0.4VTi, 0.6VTi and 0.8VTi showed 100% chlorobenzene conversion at 250 °C. The effect of vanadium loading on the catalysts have been characterized by means of XRD, SEM, TEM, ICP-OES, N2 adsorption–desorption at 77 K, Raman, NH3-TPD and H2-TPR. The reaction mechanism of chlorobenzene over the as-prepared catalysts was also proposed by in situ DRIFTS.

As an emerging p-conjugated materials, graphitic carbon nitride (g-C3N4) has captured worldwide attention due to impending energy crisis and increasingly serious environmental contamination. In this work, the two-dimensional (2D) MgFe mixed metal oxide (MMO) derived from the layered double hydroxides precursor was employed to construct 2D/2D nanosheet heterojunction with g-C3N4. The formed CN/MgFe-30 nanosheet heterojunctions exhibited the optimal photocatalytic hydrogen production about 6.64 times (1.26 mmol/g−1·h−1) than that of pure g-C3N4 under the visible light irradiation, which were attributed to unique inter-plane 2D/2D structure and excellent synergistic effect between g-C3N4 and MgFe MMO. The experiment characterization proved that MgFe MMO nanosheet not only suppressed the overgrowth of g-C3N4, resulting in the formation of nanoscale g-C3N4, but also facilitated the photoinduced carrier separation and transfer based on 2D/2D CN/MgFe-X nanosheet heterojunctions. This proposed synthesis strategy pave a way to realize the large-scale production of nano-g-C3N4 based 2D/2D nanosheet heterojunctions photocatalysts for hydrogen production.

SVM (Support Vector Machine) is a modern Data-Mining method. It is good at processing large amounts of data and has high accuracy. In this paper, an indoor 60 GHz millimeter wave channel model based on PSO (Particle Swarm Optimization) optimized SVM is established. The prediction results of GA (Genetic Algorithm) and Grid-Search optimized SVM are compared. The simulation results show the PSO optimized SVM model has high prediction accuracy