An All-Solid-State Phosphate Electrode with H3PO4 Doped Polyaniline as the Sensitive Layer

We here describe the construction of a highly sensitive and selective all-solid-state phosphate electrode based on polyaniline and H3PO4 doped polyaniline. The polyaniline layer was electroplated on the gold substrate with Chronoamperometry method and was in-situ doped by H3PO4. The Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM, EDS) and contact angle measurement was taken to explain the difference of the two layers. This electrode can be used in both freshwater and seawater systems. In both of the two systems, the electrode exhibits linear response in the concentration range 10-1 to 10-6 M with detection limit of 10-6 M. and response time of <1 seconds. The selectivity of the electrodes was also studied in 10-1-10-5 M KH2PO4 solutions containing either 0.01 M sulfate, nitrate, chloride as the interference ions. During 12 hours continuous monitoring in 10-3 M KH2PO4 with 3.5% NaCl the potential drift was 0.05 mV/h and the lifetime of the electrode was over 40 days when preserved in this solutionpublishersversionPeer reviewe

Syntaxin of plants71 plays essential roles in plant development and stress response via regulating pH homeostasis

SYP71, a plant-specific Qc-SNARE with multiple subcellular localization, is essential for symbiotic nitrogen fixation in nodules in Lotus, and is implicated in plant resistance to pathogenesis in rice, wheat and soybean. Arabidopsis SYP71 is proposed to participate in multiple membrane fusion steps during secretion. To date, the molecular mechanism underlying SYP71 regulation on plant development remains elusive. In this study, we clarified that AtSYP71 is essential for plant development and stress response, using techniques of cell biology, molecular biology, biochemistry, genetics, and transcriptomics. AtSYP71-knockout mutant atsyp71-1 was lethal at early development stage due to the failure of root elongation and albinism of the leaves. AtSYP71-knockdown mutants, atsyp71-2 and atsyp71-3, had short roots, delayed early development, and altered stress response. The cell wall structure and components changed significantly in atsyp71-2 due to disrupted cell wall biosynthesis and dynamics. Reactive oxygen species homeostasis and pH homeostasis were also collapsed in atsyp71-2. All these defects were likely resulted from blocked secretion pathway in the mutants. Strikingly, change of pH value significantly affected ROS homeostasis in atsyp71-2, suggesting interconnection between ROS and pH homeostasis. Furthermore, we identified AtSYP71 partners and propose that AtSYP71 forms distinct SNARE complexes to mediate multiple membrane fusion steps in secretory pathway. Our findings suggest that AtSYP71 plays an essential role in plant development and stress response via regulating pH homeostasis through secretory pathway

Computation of Wave Attenuation and Dispersion, by Using Quasi-Static Finite Difference Modeling Method in Frequency Domain

In seismology, seismic numerical modeling is regarded as a useful tool to interpret seismic responses. The presence of subsurface heterogeneities at various scales can lead to attenuation and dispersion during seismic wave propagation. In ongoing global research, the study of wave attenuation and velocity dispersion due to wave induced fluid flow (WIFF) at mesoscopic scale become the subject of great interest. Although, seismic modeling technique is efficient in estimating wave attenuation and velocity dispersion due to wave induced fluid flow (WIFF) at mesoscopic scale.  It is possible to further improve the efficiency to accurately predict wave attenuation and velocity dispersion at mesoscopic scale. To achieve this goal, a quasi-static finite difference modeling method in frequency domain is implemented to estimate frequency dependent P-wave modulus of mesoscopic heterogeneous porous media. The estimated complex and frequency dependent P-wave modulus will assist to estimate frequency dependent wave attenuation and velocity dispersion within a saturated porous media exhibiting mesoscopic heterogeneities. The proposed quasi-static finite difference modeling method is further validated with theoretically predicted high and low-frequency limits and also with the analytical solution of White’s 1-D model which is for rock saturated with two immiscible fluids creating heterogeneity at mesoscopic scale. Furthermore, the proposed method is further extended to rock saturated with three phase fluids exhibiting heterogeneity at mesoscopic scale. Subsequently, seismic wave attenuation (inverse quality factor Q-1) and the effects on P-wave velocity in 1-D models with different patch size under same gas saturation were also computed. Our proposed quasi-static method is simple to be implemented by the computing scheme of parallelization and have a potential to extend it for two-dimensional case comparatively in a flexible way

Amplitude Variation with Offsets and Azimuths Simultaneous Inversion for Elastic and Fracture Parameters

Azimuthal elastic inversion or AVO/AVA analysis has proven to be effective for fracture description and stress evaluation in unconventional resource plays. Fracture weakness including normal and tangential weakness from linear slip theory bridge the seismic data and fracturing parameters as intermediate parameters. However, the stability of the azimuthal elastic inversion methods available for anisotropic parameters or fracture parameters in field data remains challenging. This study explores a practical azimuthal simultaneous elastic inversion method in heterogeneous medium for fracture weakness estimation. Taking the heterogeneity and anisotropy of fracture media into consideration, and based on perturbation theory and stable phase approximation, the fracture medium can be considered as the superimposition of background medium and perturbation medium, and then the seismic scattering coefficient of fracture media can be derived. This equation establishes the relationship between seismic data and fracture weakness together with elastic parameters like P-wave and S-wave moduli and weaknesses. With this equation, a heterogeneous inversion method is proposed. This method implements the estimation of P-wave and S-wave moduli and fracture weaknesses simultaneously, and the constraint from initial model and multi-iterations enhances the stability of this method. In this approach, the parameters of the perturbation medium are initially estimated, and then they can be superposed to the parameters of the known background medium as the renewal parameters of the background medium in next iteration. We can yield the final estimation of the parameters in heterogeneous medium after several iterations when the last two estimated results are similar. Model test and field data examples verify the feasibility and potential of the proposed approach

Full waveform inversion based on morphological component analysis seismic data reconstruction

Seismic exploration is the most important and the most effective method of solving the petroleum exploration problem which uses seismic data to cognize the underground geological structure and orientate oil and gas traps. Full waveform inversion (FWI) could build precision velocity model of earth medium through the extraction of the full information content of the seismic data. The quality of seismic data has significant impact on the full waveform inversion. However, field seismic data acquisition is restricted by various conditions, the observation system is often irregular, seismic data may be missing. Irregularity or missing of seismic data will seriously affect the seismic processing and interpretation results. Seismic data reconstruction methods can be used to restore the missing data, then improve the quality of seismic data. In this paper, we utilize the morphological component analysis (MCA) method to reconstruct the seismic data. Then we combine this method with full waveform inversion to provide high quality seismic data which used as input for FWI. Experimental results show that not only can the MCA method rebuild seismic data accurately but also has the effect of denoising. Full waveform inversion based on MCA seismic data reconstruction can obtain higher precision subsurface velocity. We apply this method to the field seismic data, the quality of seismic data is improved, and can obtain better inversion results