1,162 research outputs found
Nanoscale Au-ZnO heterostructure developed by atomic layer deposition towards amperometric H2O2 detection
Nanoscale Au-ZnO heterostructures were fabricated on 4-in. SiO2/Si wafers by the atomic layer deposition (ALD) technique. Developed Au-ZnO heterostructures after post-deposition annealing at 250 degrees C were tested for amperometric hydrogen peroxide (H2O2) detection. The surface morphology and nanostructure of Au-ZnO heterostructures were examined by field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), etc. Additionally, the electrochemical behavior of Au-ZnO heterostructures towards H2O2 sensing under various conditions is assessed by chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that ALD-fabricated Au-ZnO heterostructures exhibited one of the highest sensitivities of 0.53 mu A mu M(-1)cm(-2), the widest linear H2O2 detection range of 1.0 mu M-120mM, a low limit of detection (LOD) of 0.78 mu M, excellent selectivity under the normal operation conditions, and great long-term stability. Utilization of the ALD deposition method opens up a unique opportunity for the improvement of the various capabilities of the devices based on Au-ZnO heterostructures for amperometric detection of different chemicals
Towards Complex Backgrounds: A Unified Difference-Aware Decoder for Binary Segmentation
Binary segmentation is used to distinguish objects of interest from
background, and is an active area of convolutional encoder-decoder network
research. The current decoders are designed for specific objects based on the
common backbones as the encoders, but cannot deal with complex backgrounds.
Inspired by the way human eyes detect objects of interest, a new unified
dual-branch decoder paradigm named the difference-aware decoder is proposed in
this paper to explore the difference between the foreground and the background
and separate the objects of interest in optical images. The difference-aware
decoder imitates the human eye in three stages using the multi-level features
output by the encoder. In Stage A, the first branch decoder of the
difference-aware decoder is used to obtain a guide map. The highest-level
features are enhanced with a novel field expansion module and a dual residual
attention module, and are combined with the lowest-level features to obtain the
guide map. In Stage B, the other branch decoder adopts a middle feature fusion
module to make trade-offs between textural details and semantic information and
generate background-aware features. In Stage C, the proposed difference-aware
extractor, consisting of a difference guidance model and a difference
enhancement module, fuses the guide map from Stage A and the background-aware
features from Stage B, to enlarge the differences between the foreground and
the background and output a final detection result. The results demonstrate
that the difference-aware decoder can achieve a higher accuracy than the other
state-of-the-art binary segmentation methods for these tasks
A New Two-Dimensional Functional Material with Desirable Bandgap and Ultrahigh Carrier Mobility
Two-dimensional (2D) semiconductors with direct and modest bandgap and
ultrahigh carrier mobility are highly desired functional materials for
nanoelectronic applications. Herein, we predict that monolayer CaP3 is a new 2D
functional material that possesses not only a direct bandgap of 1.15 eV (based
on HSE06 computation), and also a very high electron mobility up to 19930 cm2
V-1 s-1, comparable to that of monolayer phosphorene. More remarkably, contrary
to the bilayer phosphorene which possesses dramatically reduced carrier
mobility compared to its monolayer counterpart, CaP3 bilayer possesses even
higher electron mobility (22380 cm2 V-1 s-1) than its monolayer counterpart.
The bandgap of 2D CaP3 can be tuned over a wide range from 1.15 to 0.37 eV
(HSE06 values) through controlling the number of stacked CaP3 layers. Besides
novel electronic properties, 2D CaP3 also exhibits optical absorption over the
entire visible-light range. The combined novel electronic, charge mobility, and
optical properties render 2D CaP3 an exciting functional material for future
nanoelectronic and optoelectronic applications
Sulfuric Acid and Ammonia Generation by Bipolar Membranes Electrodialysis: Transport Rate Model for Ion and Water through Anion Exchange Membrane
Regeneration of sulfuric acid and ammonia from ammonium sulfate by bipolar membrane electrodialysis (BMED) coupling with stripping ammonia by air-blowing was studied. The result showed that it was feasible to regenerate sulfuric acid and ammonia from ammonium sulfate solution using this method. Empirical models to describe the ion and water transport behaviors through anion exchange membrane for BMED system were successfully developed. The models were valid to evaluate water transport rate and ion transport behavior for anion exchange membrane under similar operation conditions. Comparison of calculated values with experimental data indicated that the models were reliable to describe the water and ion transport behavior through anion exchange membrane for BMED system and also be used to predict the water transport and ion transport behaviors for other current density under similar operation condition
Impact of imperfect angle estimation on spatial and directional modulation
In this paper, we investigate the impact of imperfect angle estimation (IAE) on spatial and directional modulation (SDM) systems, assuming that the signal experiences line of sight (LoS) propagation. In SDM systems with IAE, the variation is analyzed in detail, when there is a mismatch between the beamforming and precise channel matrices. Based on the union bound and statistics theory, the average bit error probabilities (ABEPs) for both the legitimate user and eavesdropper are derived. In addition, the ergodic rate is also quantified with IAE. Simulation results are presented to show that the achieved theoretical ABEPs are useful in quantifying the potential performance penalty. We also show that the mismatch between the beamforming and precise channel matrices will become greater with the increase in direction measurement error (DME), which affects the detection for both the legitimate user and eavesdropper. On the other hand, due to the effect of IAE, the SDM requires more signal-to-noise ratio (SNR) gain to achieve a stable ergodic secrecy rate
Dynamic Mechanical Properties and Microstructure of Graphene Oxide Nanosheets Reinforced Cement Composites
This paper presents an experimental investigation on the effect of uniformly dispersed graphene oxide (GO) nanosheets on dynamic mechanical properties of cement based composites prepared with recycled fine aggregate (RFA). Three different amounts of GO, 0.05%, 0.10%, and 0.20% in mass of cement, were used in the experiments. The visual inspections of GO nanosheets were also carried out after ultrasonication by transmission electron microscope (TEM) atomic force microscope (AFM), and Raman to characterize the dispersion effect of graphite oxide. Dynamic mechanical analyzer test showed that the maximum increased amount of loss factor and storage modulus, energy absorption was 125%, 53%, and 200% when compared to the control sample, respectively. The flexural and compressive strengths of GO-mortar increased up to 22% to 41.3% and 16.2% to 16.4% with 0.20 wt % GO at 14 and 28 days, respectively. However the workability decreased by 7.5% to 18.8% with 0.05% and 0.2% GO addition. Microstructural analysis with environmental scanning electron microscopy (ESEM)/backscattered mode (BSEM) showed that the GO-cement composites had a much denser structure and better crystallized hydration products, meanwhile mercury intrusion porosimetry (MIP) testing and image analysis demonstrated that the incorporation of GO in the composites can help in refining capillary pore structure and reducing the air voids content
Three-dimensional structure-activity relationship modeling of cross-reactivities of a polyclonal antibody against pyrene by comparative molecular field analysis
Immunoassays have been regarded as a possible alternative or supplement for measuring polycyclic aromatic hydrocarbons (PAHs) in the environment. Since there are too many potential cross-reactants for PAH immunoassays, it is difficult to determine all the cross-reactivities (CRs) by experimental tests. In this study, the quantitative structure-activity relationship (QSAR) technique, comparative molecular field analysis (CoMFA), was applied to predict the CRs of a polyclonal antibody against pyrene. The CoMFA model developed shows that the CRs of the compounds are correlated to their 3D structure (n = 14, q2=0.527, r2=0.944, and Standard Error (SE) = 0.22478). The contributions of the steric and electrostatic fields to CRs are 95 and 5%, respectively. The results of the correlation predicted the CRs with actual CRs of randomly selected test compounds and showed that the developed model has good prediction ability. The QSAR model has been applied to predict the CRs of other 17 PAHs. The 3D-QSAR model and its respective contour plot could be useful tools to further understand the molecular nature of antibody-antigen interactions
Alleviation of cadmium toxicity in cucumber (Cucumis sativus) seedlings by the application of selenium
In the present study, the role of selenium in cadmium toxicity was investigated in cucumber seedlings by hydroponic experiments. The application of Se for cucumber exposed to Cd significantly reduced Cd accumulation in all tissues, elevated Cd-depressed chlorophyll content, and improved photosynthetic performance. External Se significantly reduced ·OH, H2O2 and malondialdehyde content. Exogenous Se balanced Cd-depressed elements (e.g., Se enhanced Cd-induced decreases in root Zn, leaf/stem/root Mn concentrations) and carbohydrate contents. External Se also significantly decreased the Cd-induced increases in Na+K+-, Ca2+Mg2+- and total ATPase activities, which recovered almost to control level. Results indicate that application of Se can alleviate Cd toxicity in cucumber seedlings by reducing Cd uptake and reactive oxygen species (ROS) accumulation, moreover protecting photosynthetic machinery from damaging, balancing elements and carbohydrate contents, and improving ATPase activities in cucumber
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