scholarly journals Electrochemical Biosensor Based on Optimized Biocomposite for Organophosphorus and Carbamates Pesticides Detection

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
R. Montes ◽  
F. Céspedes ◽  
D. Gabriel ◽  
M. Baeza
Keyword(s):  
Electrochemical Properties ◽  
Electrochemical Impedance ◽  
Signal To Noise Ratio ◽  
Tap Water ◽  
Electrochemical Techniques ◽  
High Signal ◽  
High Electron ◽  
Optimal Composition ◽  
Order Of Magnitude ◽  
Standard Composition

This paper presents the characterization and optimization of biosensors based on graphite-epoxy which incorporates the enzyme acetylcholinesterase (AChE). By means of advanced electrochemical techniques, such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), the characterization and optimization of graphite-epoxy-AChE biosensors have been performed. In order to obtain sensitive electrodes, the optimal composition of the transducer material (graphite-epoxy-enzyme ratio) was studied. The optimization of the conductive particles distribution inside the biomaterial has allowed an improvement of the electrochemical properties. Optimal composition guarantees improving electrochemical properties required, such as high electron-transfer rate, high signal-to-noise ratio, and suitable sensitivity. The optimal biocomposite composition range was obtained between 16% and 17% of graphite and 0.12% of AChE. The biosensors were applied to the analysis of different pesticides, organophosphorus and carbamates, using indirect measurements based on enzymatic inhibition process. These optimized biosensors present detection limit one order of magnitude lower compared to the standard composition (nonoptimized) and allow achieving concentrations lower than the established ones by the pesticides regulation. Finally, spiked tap water samples with pesticides were analyzed with the optimized biosensors.

scholarly journals Vertical-Type Ni/GaN UV Photodetectors Fabricated on Free-Standing GaN Substrates

2019 ◽  
Vol 9 (14) ◽  
pp. 2895 ◽  
Author(s):  
Bing Ren ◽  
Meiyong Liao ◽  
Masatomo Sumiya ◽  
Jian Huang ◽  
Linjun Wang ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Schottky Contact ◽  
High Signal ◽  
Threading Dislocation ◽  
High Electron ◽  
Free Standing ◽  
Lower Growth ◽  
Schottky Type ◽  
Lower Growth Rate ◽  
Self Powered

The authors report on a vertical-type visible-blind ultraviolet (UV) Schottky-type photodetector fabricated on a homoepitaxial GaN layer grown on free-standing GaN substrates with a semi-transparent Ni Schottky contact. Owing to the high-quality GaN drift layer with low-density threading dislocation and high electron mobility, the UV photodetector shows a high specific detectivity of more than 1012 Jones and a UV/visible discrimination ratio of ~1530 at −5 V. The photodetector also shows the excellent self-powered photo-response and a high signal-to-noise ratio of more than 104 at zero voltage. It is found that a relatively lower growth rate for the GaN epilayer is preferred to improve the performance of the Schottky-type photodetectors due to the better microstructure and surface properties.

scholarly journals Radial Carboxyterminal Peptides of Tubulin Directly Imaged in Microtubules by Electron Microscopy Tomography Exploiting Emplitude Contrast

2021 ◽  
Author(s):  
Andrea Fera ◽  
Thomas Reese ◽  
Joshua Zimmerberg ◽  
Dan Sackett
Keyword(s):  
Electron Microscopy ◽  
Outer Surface ◽  
Electron Beam Irradiation ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Signal ◽  
High Electron ◽  
Microscopy Image ◽  
Multiple Samples

Abstract Tubulin carboxyterminal tails (CTT) are peptides of 10-20 amino acids, unstructured and acidic, that vary in sequence between tubulin isotypes and are exposed on the outer surface of microtubules (MTs). These peptides have, so far, eluded direct visualization. In this report, electron microscopy tomography was applied to isolated MTs stained with Uranyl and tungstate salts demonstrated to resist sustained electron beam irradiation. Such resistance of high electron doses allows each electron microscopy image to be recorded with a high signal-to-noise ratio. Corresponding tomograms reconstructed from tilt series at high magnification show exceptional resolution of details, revealing features of average dimension ~ 1 nm without the need of averaging multiple samples. The known three-dimensional structure of the MT wall is apparent. But now images also reveal small stalks on the outer surface of MTs. Inspection of virtual sections demonstrates that the stalks are up to ~2.5 nm long and ~1 nm wide (at half length), protruding every 4 ± 0.8 (22) nm along the microtubule. This spacing corresponds to one stalk per tubulin monomer. The grafting point on each monomer is not random but is positioned at one end of each monomer, identifying that end as toward the (-) end of the MT. The stalks are not observed following CTT removal with subtilisin. We conclude that these stalks are the CTT peptides of tubulin.

A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

2020 ◽  
Vol 64 (1-4) ◽  
pp. 951-958
Author(s):  
Tianhao Liu ◽  
Yu Jin ◽  
Cuixiang Pei ◽  
Jie Han ◽  
Zhenmao Chen
Keyword(s):  
Power Plants ◽  
Signal To Noise Ratio ◽  
Small Diameter ◽  
Performance Testing ◽  
Guided Wave ◽  
High Signal ◽  
Receiver Coil ◽  
Signal To Noise ◽  
Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

Influence of VC and FEC Additives on Interphase Properties of Carbon in Li-Ion Cells Investigated by Combined EIS & EQCM-D

2020 ◽  
Author(s):  
Paul Kitz ◽  
Matthew Lacey ◽  
Petr Novák ◽  
Erik Berg
Keyword(s):  
Electrochemical Impedance ◽  
Solid Electrolyte Interphase ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Gas Analysis ◽  
Side Reactions ◽  
Ion Diffusion ◽  
Battery Cell ◽  
Anode Passivation ◽  
Order Of Magnitude ◽  
Li Ion

<div>The electrolyte additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are well known for increasing the lifetime of a Li-ion battery cell by supporting the formation of an effective solid electrolyte interphase (SEI) at the anode. In this study combined simultaneous electrochemical impedance spectroscopy (EIS) and <i>operando</i> electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) are employed together with <i>in situ</i> gas analysis (OEMS) to study the influence of VC and FEC on the passivation process and the interphase properties at carbon-based anodes. In small quantities both additives reduce the initial interphase mass loading by 30 to 50 %, but only VC also effectively prevents continuous side reactions and improves anode passivation significantly. VC and FEC are both reduced at potentials above 1 V vs. Li<sup>+</sup>/Li in the first cycle and change the SEI composition which causes an increase of the SEI shear storage modulus by over one order of magnitude in both cases. As a consequence, the ion diffusion coefficient and conductivity in the interphase is also significantly affected. While small quantities of VC in the initial electrolyte increase the SEI conductivity, FEC decomposition products hinder charge transport through the SEI and thus increase overall anode impedance significantly. </div>

Application of Novel Low Current OBIRCH Amplifier and Nanoprobing to Identify Subtle Leakages in Advanced Node Technologies

2018 ◽  
Author(s):  
Satish Kodali ◽  
Liangshan Chen ◽  
Yuting Wei ◽  
Tanya Schaeffer ◽  
Chong Khiam Oh
Keyword(s):  
Signal To Noise Ratio ◽  
Semiconductor Industry ◽  
Fault Isolation ◽  
Ring Oscillator ◽  
High Signal ◽  
The Novel ◽  
Resistance Change ◽  
Three Samples ◽  
Relative Threshold ◽  
First Time

Abstract Optical beam induced resistance change (OBIRCH) is a very well-adapted technique for static fault isolation in the semiconductor industry. Novel low current OBIRCH amplifier is used to facilitate safe test condition requirements for advanced nodes. This paper shows the differences between the earlier and novel generation OBIRCH amplifiers. Ring oscillator high standby leakage samples are analyzed using the novel generation amplifier. High signal to noise ratio at applied low bias and current levels on device under test are shown on various samples. Further, a metric to demonstrate the SNR to device performance is also discussed. OBIRCH analysis is performed on all the three samples for nanoprobing of, and physical characterization on, the leakage. The resulting spots were calibrated and classified. It is noted that the calibration metric can be successfully used for the first time to estimate the relative threshold voltage of individual transistors in advanced process nodes.

The study of the electrochemical properties of zinc-rich coating on the base of water sodium silicate

2019 ◽  
Vol 24 (4) ◽  
pp. 51-58
Author(s):  
Le Hong Quan ◽  
Nguyen Van Chi ◽  
Mai Van Minh ◽  
Nong Quoc Quang ◽  
Dong Van Kien
Keyword(s):  
Carbon Steel ◽  
Electrochemical Properties ◽  
Sodium Silicate ◽  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Electrical Contact ◽  
Electrochemical Impedance Spectra ◽  
Pure Zinc ◽  
Electric Circuits

The study examines the electrochemical properties of a coating based on water sodium silicate and pure zinc dust (ZSC, working title - TTL-VN) using the Electrochemical Impedance Spectra (EIS) with AutoLAB PGSTAT204N. The system consists of three electrodes: Ag/AgCl (SCE) reference electrode in 3 M solution of KCl, auxiliary electrode Pt (8x8 mm) and working electrodes (carbon steel with surface treatment up to Sa 2.5) for determination of corrosion potential (Ecorr) and calculation of equivalent electric circuits used for explanation of impedance measurement results. It was shown that electrochemical method is effective for study of corrosion characteristics of ZSC on steel. We proposed an interpretation of the deterioration over time of the ability of zinc particles in paint to provide cathodic protection for carbon steel. The results show that the value of Ecorr is between -0,9 and -1,1 V / SCE for ten days of diving. This means that there is an electrical contact between the zinc particles, which provides good cathodic protection for the steel substrate and most of the zinc particles were involved in the osmosis process. The good characteristics of the TTL-VN coating during immersion in a 3,5% NaCl solution can also be explained by the preservation of corrosive zinc products in the coating, which allows the creation of random barrier properties.

scholarly journals VS2 as saturable absorber for Q-switched pulse generation

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2569-2576 ◽  
Author(s):  
Lu Li ◽  
Lihui Pang ◽  
Qiyi Zhao ◽  
Yao Wang ◽  
Wenjun Liu
Keyword(s):  
Saturable Absorber ◽  
Nonlinear Optical ◽  
Modulation Depth ◽  
Signal To Noise Ratio ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Pulse Generation ◽  
High Signal ◽  
Power Pulse ◽  
Metal Dichalcogenides

AbstractTransition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

scholarly journals Counterfactual ghost imaging

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jonte R. Hance ◽  
John Rarity
Keyword(s):  
Signal To Noise Ratio ◽  
Ghost Imaging ◽  
Signal To Noise ◽  
Interesting Phenomenon ◽  
Order Of Magnitude ◽  
Noise Ratio

AbstractWe give a protocol for ghost imaging in a way that is always counterfactual—while imaging an object, no light interacts with that object. This extends the idea of counterfactuality beyond communication, showing how this interesting phenomenon can be leveraged for metrology. Given, in the infinite limit, no photons ever go to the imaged object, it presents a method of imaging even the most light-sensitive of objects without damaging them. Even when not in the infinite limit, it still provides a many-fold improvement in visibility and signal-to-noise ratio over previous protocols, with over an order of magnitude reduction in absorbed intensity.

Performance of coatings containing treated silica fume in the corrosion protection of reinforced concrete

2018 ◽  
Vol 47 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Nivin M. Ahmed ◽  
Mostafa G. Mohamed ◽  
Reham H. Tammam ◽  
Mohamed R. Mabrouk
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Dual Function ◽  
Core Shell ◽  
Protection Efficiency ◽  
Content Type ◽  
Anticorrosive Pigments

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

scholarly journals Detection and localization of multiple small damages in beam

2021 ◽  
Vol 13 (1) ◽  
pp. 168781402098732
Author(s):  
Ayisha Nayyar ◽  
Ummul Baneen ◽  
Syed Abbas Zilqurnain Naqvi ◽  
Muhammad Ahsan
Keyword(s):  
Frequency Response ◽  
Natural Frequencies ◽  
Signal To Noise Ratio ◽  
Moving Average ◽  
A Priori ◽  
Damage Index ◽  
High Signal ◽  
Frequency Range ◽  
Spatial Locality ◽  
System Frequency

Localizing small damages often requires sensors be mounted in the proximity of damage to obtain high Signal-to-Noise Ratio in system frequency response to input excitation. The proximity requirement limits the applicability of existing schemes for low-severity damage detection as an estimate of damage location may not be known  a priori. In this work it is shown that spatial locality is not a fundamental impediment; multiple small damages can still be detected with high accuracy provided that the frequency range beyond the first five natural frequencies is utilized in the Frequency response functions (FRF) curvature method. The proposed method presented in this paper applies sensitivity analysis to systematically unearth frequency ranges capable of elevating damage index peak at correct damage locations. It is a baseline-free method that employs a smoothing polynomial to emulate reference curvatures for the undamaged structure. Numerical simulation of steel-beam shows that small multiple damages of severity as low as 5% can be reliably detected by including frequency range covering 5–10th natural frequencies. The efficacy of the scheme is also experimentally validated for the same beam. It is also found that a simple noise filtration scheme such as a Gaussian moving average filter can adequately remove false peaks from the damage index profile.

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