Pair Of Peaks Research Articles

Microdialysis-integrated HPLC system with dual-electrode detection using track-etched membrane electrodes for in vivo monitoring of dopamine dynamics

A capillary high-performance liquid chromatography (HPLC) system equipped with a dual-electrode detector utilizing track-etched membrane electrodes (TEMEs) was combined with a microdialysis sampling setup. The electrochemical detector benefits from the high electrolysis efficiency of TEMEs, allowing for calibration-free coulometric detection and simplifying data analysis to determine the dopamine recovery through a dialysis probe. Additionally, this system was used for in vivo monitoring of dopamine in the right striatum of a mouse brain. Temporal changes in dopamine levels, including an exponential decay immediately after the dialysis probe insertion and an excess release of dopamine induced by a high concentration of potassium ions, confirmed the system’s proper operation. Furthermore, subsequent measurements following the intraperitoneal injection of mirtazapine showed no increase in dopamine levels in the right dorsal striatum. The dual-electrode system displayed characteristic dopamine detection behavior, with anodic and cathodic peak pairs indicative of reversible electrochemical reactions. This capability facilitated the identification of the dopamine peak within the complex chromatogram of the mouse brain dialysate. The consistency between dopamine collection efficiency from standard solutions and dialysate indicated the absence of interfering electroactive substances overlapping with the dopamine peak in the chromatogram. This integrated analysis system successfully tracked temporal fluctuations in dopamine concentration within the mouse brain.

Performances of MnO2 and SnO2 Coated MnO2 as Cathode Materials for Aqueous Rechargeable Zinc-ion Batteries

In this study, the micro-emulsion method was used to create the manganese-based cathode materials MnO2 and MnO2@SnO2. For the use as cathode materials in rechargeable zinc-ion batteries, MnO2 and SnO2 coated MnO2@SnO2 were synthesized. FT-IR, Powder X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), and UV-visible Spectroscopy were used to characterize the as-prepared materials. Electrochemical impedance spectroscopy (EIS), battery charge-discharge (BCD), and cyclic voltammetry (CV) techniques were used to investigate the electrochemical properties of the prepared cathode materials for aqueous rechargeable zinc-ion batteries (ARZIBs). The CV profiles were measured in the potential range of 2.1-1.0 V at a scan rate of 20 mV/s. A pair of redox peaks can be seen in the cycle of CV curves. Charge/discharge cycles of SnO2 coated MnO2@SnO2 electrodes are higher than those of pristine MnO2. SnO2 coated MnO2@SnO2 electrodes have better initial charge/discharge capacities than pristine MnO2 electrodes, which is a factor to take into account. In the first cycle, SnO2 coated MnO2@SnO2 electrode has a 26% higher charge capacity than the bare MnO2 electrode. The SnO2 coating on MnO2 may be the cause of the enhanced charge and discharge capabilities of MnO2@SnO2. J. of Sci. and Tech. Res. 5(1): 83-92, 2023

The Deposition of Lead on a Pt(100) Electrode and the Effects on the Oxidation of Formic Acid

The electrodeposition of foreign metals on a platinum (Pt) electrode can be used to alter the electrochemical properties of the modified electrode. The current study employed in situ scanning tunneling microscopy (STM) to characterize the spatial structures of a monolayer and multilayer lead (Pb) electrodeposited on an ordered Pt(100) electrode in 0.1 M perchloric acid (HClO4) with and without formic acid under potential control. The Pt(100) bead crystal used in this study was pretreated by a modified annealing and quenching method, producing a long-range ordered, unreconstructed (1 × 1) surface. The underpotential deposition (UPD) of Pb on the Pt(100) electrode resulted in a pair of sharp and reversible peak at 0.5 V (vs. Ag/AgCl), prior to the bulk deposition at E < -0.45 V in 0.1 M HClO4 + 1 mM Pb(ClO4)2. Cyclic potential sweeping in the UPD regimes resulted in a stable voltammogram, but bulk Pb deposition led to varying morphologies of the profiles. Atomic resolution STM images were obtained to reveal a well-ordered Pt(100)-(√2 × √2)R45°-Pb structure and elongated rows of Pb aggregates and local (√2 × 2√2) R45° in the initial and final stages of Pb UPD, respectively. Bulk Pb deposition at E < -0.5 V led to a crystalline Pb film, but a roughened Pt(100) surface was imaged after the Pb deposit was anodically stripped. The activity of the Pt(100) electrode toward formic acid oxidation was nearly tripled after being modified with a sub-monolayer of Pb, and increased by another 20 % when it was loaded with multilayer Pb.

Energetics and Redox Kinetics of Pure Ferrocene-Terminated N-Heterocyclic Carbene Self-Assembled Monolayers on Gold.

N-heterocyclic carbene (NHC) self-assembled monolayers (SAMs) on gold have received considerable attention, but little is known about the lateral interactions between neighboring NHC molecules, their stability when subjected to aggressive oxidizing/reducing conditions, and their interactions with solution ions, all of which are essential for their use in a wide range of applications. To address these deficiencies, we present a comprehensive investigation of two different ferrocene (Fc)-terminated NHC SAMs with different chain lengths and linking groups. Pure monolayers of Fc-terminated NHCs display only a single, symmetrical pair of redox peaks, implying the formation of a homogeneous SAM structure with uniformly distributed Fc/Fc+ redox centers. By comparison, pure Fc-alkylthiol SAMs exhibit complex and impractical redox chemistry and require surface dilution in order to achieve reproducible properties. The NHC SAMs examined in this study exhibit very fast Fc redox kinetics and comparable or even superior stability against the application of multiple potential cycles or long-time holding at constant potential compared to alkylthiol SAMs. Furthermore, ion pairing of Fc+ and hydrophobic perchlorate and other hydrophilic anions is observed with Fc-NHC SAMs, highlighting conditions favorable for future applications of these monolayers. This study should therefore shed light on the very promising characteristics of redox-active NHC SAMs as an alternative to traditional Fc-alkylthiol SAMs for multiple practical applications, including in sensors and electrocatalysis.

Structural phase transition and optical properties of zero-dimensional cobalt bromide hybrid material

Zero-Dimensional (0D) metal halide materials have recently emerged as a class of potential optoelectronic materials because of the structural diversity and superior photophysical properties. Here we report a 0D cobalt bromide hybrid material, [Br(CH2)3NH3]2CoBr4 (BPA-CoBr4, BPA=Br(CH2)3NH3, 3-Bromopropylamine), in which the isolated metal halide tetrahedron (CoBr42-) is completely separated each other and surrounded by the organic ligand Br(CH2)3NH3+. Differential scanning calorimetry (DSC) measurements exhibit BPA-CoBr4 undergoes a first-order structural phase transition, as clearly visible to a pair of weak peaks at 340 K (heating) and 317 K (cooling). Single crystal X-ray diffractions were carried out at 293 K and 360 K to explain the phase transformation mechanism, indicating it is an isostructural order–disorder type. The crystal structures which both crystalize in a monoclinic P21/c crystal symmetry and the most distinct difference between room-temperature and high-temperature structures is the order–disorder transition of the 3-Bromopropylamine, which is the driving force of the phase transition. The UV–vis absorption spectra reveal that BPA-CoBr4 has a steep absorption edge at 280 nm corresponding to photo energy of 4.4 eV. The density functional theory (DFT) calculations were performed to study the electronic structure with narrower indirect bandgap 3.9 eV which is lower than the experimental values. PDOS plots show that the electronic states of Co-d and Br-p orbitals are mainly contributed for the VBM and CBM of BPA-CoBr4.

Resolution Enhancement of Metabolomic J-Res NMR Spectra Using Deep Learning.

J-Resolved (J-Res) nuclear magnetic resonance (NMR) spectroscopy is pivotal in NMR-based metabolomics, but practitioners face a choice between time-consuming high-resolution (HR) experiments or shorter low-resolution (LR) experiments which exhibit significant peak overlap. Deep learning neural networks have been successfully used in many fields to enhance quality of natural images, especially with regard to resolution, and therefore offer the prospect of improving two-dimensional (2D) NMR data. Here, we introduce the J-RESRGAN, an adapted and modified generative adversarial network (GAN) for image super-resolution (SR), which we trained specifically for metabolomic J-Res spectra to enhance peak resolution. A novel symmetric loss function was introduced, exploiting the inherent vertical symmetry of J-Res NMR spectra. Model training used simulated high-resolution J-Res spectra of complex mixtures, with corresponding low-resolution spectra generated via blurring and down-sampling. Evaluation of peak pair resolvability on J-RESRGAN demonstrated remarkable improvement in resolution across a variety of samples. In simulated plasma data, 100% of peak pairs exhibited enhanced resolution in super-resolution spectra compared to their low-resolution counterparts. Similarly, enhanced resolution was observed in 80.8-100% of peak pairs in experimental plasma, 85.0-96.7% in urine, 94.4-98.9% in full fat milk, and 82.6-91.7% in orange juice. J-RESRGAN is not sample type, spectrometer or field strength dependent and improvements on previously acquired data can be seen in seconds on a standard desktop computer. We believe this demonstrates the promise of deep learning methods to enhance NMR metabolomic data, and in particular, the power of J-RESRGAN to elucidate overlapping peaks, advancing precision in a wide variety of NMR-based metabolomics studies. The model, J-RESRGAN, is openly accessible for download on GitHub at https://github.com/yanyan5420/J-RESRGAN.

Electroanalysis of Catechol and Hydroquinone by Glassy Carbon Electrode Modified with Multi-Walled Carbon Nanotubes, β-cyclodextrin Decorated with Reduced Graphene Oxide - Gold Nanoparticle Nanocomposite

In this work, the glassy carbon electrode was modified by multi-walled carbon nanotubes, β-cyclodextrin, reduced graphene oxide, and gold nanoparticle nanocomposites GC/MWCNTs/β-CD-rGO@Au). The GC/MWCNTs/β-CD-rGO@Au electrode was utilized for simultaneous monitoring of catechol (CC) and hydroquinone (HQ). The modified electrode has a clear pair of voltammetric peaks for CC and HQ, which makes it an appropriate tool for the simultaneous determination of the two isomers. Under optimized conditions, the oxidation peak currents of CC and HQ at GC/MWCNTs/β-CD-rGO@Au were increased linearly in the 1–173 μM and 2–80 μM concentration range with the limit of detection (LOD) (based on S/N = 3) of 0.17 μM and 0.26 μM. The GC/MWCNTs/β-CD-rGO@Au exhibits adequate stability, repeatability, and recovery in analyzing two dihydroxybenzenes isomers.

Voltammetry study of CuHCF electrode in brine solutions

It is a challenge that extracting rubidium directly from the salt lakes by electrochemical method, because of the low content of rubidium ions and other complex co-existing ions in the salt lakes. Copper hexacyanoferrate (CuHCF) with good electrochemical performance in desalination and aqueous batteries, may be used as the electrode material of electrochemical extracting rubidium. In this paper, CuHCF is synthesized by one-step precipitation method by adding copper ions in K3Fe(CN)6 solution. Cyclic voltammetry is studied with the CuHCF electrode sheets in alkali metal ions and simulated brine electrolytes. The alkali metal ions insertion and de-insertion in the electrodes are mainly controlled by diffusion process with cyclic stability. The diffusion rate of K+ is the largest, Li+ the smallest. The insertion and de-insertion process are reversible in Na+, K+ and Rb+ ionic solutions. The cyclic voltammetry current of the CuHCF electrode sheet in Na+ ionic solution shows two pairs of redox peaks. The cyclic voltammetry currents of CuHCF electrode sheet in simulated brine mainly show is the peak current of that in Na+ and K+ ionic solutions.

Quantitative description of the quality of size exclusion chromatography separations

Size exclusion chromatography (SEC) is unique among chromatographic methods as it allows separation of non-retained analytes. However, such mechanism often put an analytical scientist in front of relatively poorly resolved set of peaks that may have strikingly different abundance. The description of such chromatograms needs a particular approach to accurately capture the overall quality of separation. Consequently, use of a single parameter description may not be accurate enough and therefore we introduce a dimensionless separation quality factor, which is based on five SEC specific measures (peak-to-valley, elution window width, peak widths, peak-positioning and recovery). Combining several factors allowed detailed differentiation of various simulated separations, clearly correlating column characteristics with specific contributions to separation quality whether they concern a single peak pair or entire peak landscape. The method could be further elaborated by the addition of normalized priority weighting allowing for flexible quality quantification of a relevant portion of real-life nucleic acid separation on different columns. With growing complexity of biotherapeutics to be separated, such a term is predicted to be a useful response function for purposes of factorial method optimization.

Synthesis of BiDy composite oxide nanoflakes with good electrochemical properties

Bismuth dysprosium (BiDy) composite oxide nanoflakes with a thickness of about 50 nm were synthesized using a one-step hydrothermal method. Electrodes modified with BiDy composite oxide nanoflakes exhibited a superior electrochemical behavior for detecting l-cysteine using the cyclic voltammetry (CV) method. The impacts of scan rate, electrolyte and concentration of l-cysteine on electrochemical behaviors were investigated. A pair of strong quasi-reversible CV peaks was observed at +0.03 V (cvp1) and −0.69 V (cvp1′) with peak currents of 171.2 and 171.3 μA, respectively, for a BiDy-composite-oxide-nanoflake-modified glassy carbon electrode (GCE) in 0.1 M potassium chloride (KCl) and 2 mM l-cysteine solution. The GCE modified with BiDy composite oxide nanoflakes displayed a broad range of linearity (0.001–2 mM) and a low detection limit (0.29 μM) for l-cysteine. Using a hydrothermal approach as a synthesis technique for nanoflakes, a facile and sensitive electrochemical sensor based on nanoflakes was developed for detecting l-cysteine, making it a promising approach for practical application.

Natural low corrosive phytic acid electrolytes enable green, ultrafast, stable and high-voltage aqueous proton battery

Proton is a promising charge carrier for aqueous rechargeable batteries due to its small ionic radius, fast diffusion kinetics and great abundance in nature. However, commonly-used proton battery electrolytes are strong acids, such as sulfuric acid, phosphoric acid, etc., which always leads to the notorious rapid corrosion of electrode and metal components, and thus the poor cyclability, the limited materials option and high maintenance cost. Here, we reported a new-type high-concentration phytic acid (PA) electrolytes, which exhibits marvellous superiorities including environmental friendliness, low corrosiveness, high ionic conductivity (133.3 mS cm−1) and wide working potential window (∼2.9 V) in contrast to conventional acid electrolytes. The experimental and calculation results indicated that the scarcity of free water in high-concentration PA electrolytes and the desolvation effect of the preferentially absorbed PA interfacial layer on the electrode surface work in synergy to inhibit the water activity and thus prevent electrode dissolution and side reactions. Benefiting from this, the assembled K0.2VO0.6[Fe(CN)6]0.8•6H2O (VHCF)//MoO3 button-type proton battery shows an average discharge voltage of 0.7 V with a pair of well-defined redox peak at about 1.4 V, great rate performance, excellent cycling stability (87.9% capacity retention after 1000 cycles at 5 A g−1) and superb coulombic efficiency at various current densities (1 A g−1–50 A g−1). Attributed to good anti-freezing properties of the electrolytes, the proton battery can also run normally at -60 °C and exhibit competent performance (a capacity retention of 45 mAh g−1 at 0.1 A g−1 after 540 cycles). Such green low corrosive electrolyte will be fully compatible with conventional battery fabrication process, and open brand new avenue for the development of aqueous proton battery.

Enhancing the supercapacitive performance of a carbon-based electrode through a balanced strategy for porous structure, graphitization degree and N,B co-doping

Regarding carbon-based electrodes, simultaneously establishing a well-defined meso-porous architecture, introducing abundant hetero-atoms and improving the graphitization degree can effectively enhance their capacitive performance. However, it remains a significant challenge to achieve a good balance between defects and graphitization degree. In this study, the porous structure and composition of carbon materials are co-optimised through a ‘dual-function’ strategy. Briefly, K3Fe(C2O4)3 and H3BO3 were hybridised with a gelatin aqueous solution to form a homogeneous composite hydrogel, followed by lyophilisation and carbonisation. Owing to the dual functionality of raw materials, the graphitization, activation and hetero-atom doping processes can occur simultaneously during a one-step high-temperature treatment. The resultant carbon material exhibits a high graphitization degree (ID/IG = 0.9 ± 0.1), high hetero-atom content (N: 9.0 ± 0.3 at.%, B: 6.9 ± 0.5 at.%) and a large specific area (1754 ± 58 m2/g). The as-prepared electrode demonstrates a superior capacitance of 383 ± 1F g−1 at 1 A/g. Interestingly, the cyclic voltammetry (CV) curves exhibit a distinctive pair of broad redox peaks, which is uncommon in KOH electrolyte. Experiment data and density functional theory (DFT) simulation verify that N-5, B co-doping enhances the activity of the faradic reaction of carbon electrodes in KOH electrolyte. Furthermore, the fabricated Zn-ion hybrid supercapacitor (ZHSC) based on this carbon electrode delivers a high-energy density of 140.7 W h kg−1 at a power density of 840 W kg−1.

Deciphering Aphanomyces euteiches-pea-biocontrol bacterium interactions through untargeted metabolomics

Aphanomyces euteiches causes root rot in pea, leading to significant yield losses. However, the metabolites involved in this pathosystem have not been thoroughly studied. This study aimed to fill this gap and explore mechanisms of bacterial suppression of A. euteiches via untargeted metabolomics using pea grown in a controlled environment. Chemical isotope labeling (CIL), followed by liquid chromatography-mass spectrometry (LC–MS), was used for metabolite separation and detection. Univariate and multivariate analyses showed clear separation of metabolites from pathogen-treated pea roots and roots from other treatments. A three-tier approach positively or putatively identified 5249 peak pairs or metabolites. Of these, 403 were positively identified in tier 1; 940 were putatively identified with high confidence in tier 2. There were substantial changes in amino acid pool, and fatty acid and phenylpropanoid pathway products. More metabolites, including salicylic and jasmonic acids, were upregulated than downregulated in A. euteiches-infected roots. 1-aminocyclopropane-1-carboxylic acid and 12-oxophytodienoic acid were upregulated in A. euteiches + bacterium-treated roots compared to A. euteiches-infected roots. A great number of metabolites were up- or down-regulated in response to A. euteiches infection compared with the control and A. euteiches + bacterium-treated plants. The results of this study could facilitate improved disease management.

An Effective Multiple-Bit Data Abstraction and Lossless Retrieval without Shifting

Cryptography and Steganography are two major forms of enforcing data privacy, with the former being prevalent. For small payloads, Steganography is preferred, as the data remains concealed and abstracted. The process involves embedding bits onto a carrier image. However, the disadvantage of steganography is that the carrier image gets distorted, which is a major concern when it comes to pixel sensitive images, such as forensic and medical images that aremission critical. Furthermore, due to modifications in the pixel values, the images get distorted, which can be irrecoverable. Hence, the technique of Reversible Data Hiding(RDH) can be used as a solution. Usually two methods are used under RDH, namely Histogram Shifting (HS) and Difference Expansion (DE). Histogram Shifting method shifts all pixel values between pairs of peak and zero points, which allows data to be embedded in the intermediate points. However, this method also depends on frequencies of pixel values on the image, andthe embedding capacity varies greatly on the image. In Difference Expansion Method, the difference between a pixel and its adjacent pixels is considered to embed a single bit intoone of the pixels. Here, a scheme to embed multiple bits in a pixel is proposed, which greatly enhances the embedding capacity. Initially, three horizontally adjacent pixels are takenand the difference between the rightmost and leftmost pixel iscalculated. This difference is used to classify the centre pixel as embeddable or non-embeddable. If the pixel is embeddable, anew pixel value is calculated, which comprises of the secret bits, offset bits and flag bits, without the use of any difference expansion or histogram shifting process. The secret bits and the original pixel value can be easily recovered from the modified value using the offset and flag bits. This scheme has higher embedding capacity, and lower complexity in terms of computations, when comparedwith other RDH schemes.

Quantum effects on dynamic structure factors in dense magnetized plasmas

We extend the classical magnetohydrodynamics formalism to include nonlocal quantum behavior via the phenomenological Bohm potential. We then solve the quantum magnetohydrodynamics equations to obtain a new analytical form of the dynamic structure factor (DSF), a fundamental quantity linking theory and experiments. Our results show that the three-peak structure—one central Rayleigh peak and two Brillouin peaks—of the DSF arising from quantum hydrodynamic fluctuations becomes (in general) a five-peak structure—one central Rayleigh peak and two pairs of peaks associated with fast and slow magnetosonic waves. The Bohm contribution influences the positions and characteristics (height, width, and intensity) of the peaks by introducing three significant modifications: (i) an increase in effective thermal pressure, (ii) a reduction in the adiabatic index, and (iii) an enhancement of effective thermal diffusivity. The multiple DSF peaks enable concurrent measurements of diverse plasma properties, transport coefficients, and thermodynamic parameters in magnetized dense plasmas. The potential for experimental validation of our theory looms large, particularly through future experiments conducted at state-of-the-art laser facilities. Published by the American Physical Society 2024

Feasibility of achieving two-electron K-O2 batteries.

A deep understanding of the oxygen (O2) reduction and evolution mechanisms is crucial for understanding metal-O2 batteries. It has become evident that the instability of superoxide in the presence of lithium (Li) ions and sodium (Na) ions is the root cause for the poor reversibility and energy efficiency of Li-O2 and Na-O2 batteries. A straightforward yet elegant method is stabilizing superoxide with the larger potassium (K) ions. Superoxide-based K-O2 batteries, invented by our group in 2013, are operated based on one-electron redox of O2/potassium superoxide (KO2) and have high energy efficiencies without any electrocatalysts. Nevertheless, limiting the anionic redox to O2/superoxide affects the capacity output. Therefore, it is attractive to explore the possibility of beyond KO2 in the K-O2 batteries, especially if the use of catalysts can still be avoided. In this research, solid KO2 was used as the condensed O2 source and pre-dissolved in the dimethyl sulfoxide (DMSO)-based electrolyte. It is encouraging to observe two sets of reversible peaks during the three-electrode cyclic voltammetry scan under an argon atmosphere. One pair of peaks is attributed to the KO2/potassium peroxide (K2O2) interconversion. Such redox has superb reversibility and a small overpotential of 239 mV in the absence of explicit electrocatalysts. Notably, it is further revealed that K2O2 reacts with gaseous O2. Therefore, a gas-open system with an O2 supply is unfavorable for realizing the reversible KO2/K2O2 redox, and a closed cell system with a KO2 supply as the starting active material is suggested instead.

Unraveling the potential of segment scan mass spectral acquisition for chemical isotope labeling LC-MS-based metabolome analysis: Performance assessment across different types of biological samples

BackgroundChemical isotope labeling (CIL) LC-MS is a powerful tool for metabolome analysis with high metabolomic coverage and quantification accuracy. In CIL LC-MS, the overall metabolite detection efficiency using Orbitrap MS can be further improved by employing a segment scan method where the full m/z range is divided into multiple segments for spectral acquisition with a significant increase in the in-spectrum dynamic range. Considering the metabolic complexity in different types of biological samples (e.g., feces, urine, serum/plasma, cell/tissue extracts, saliva, etc.), we report the development and evaluation of the segment scan method for metabolome analysis of different sample types. ResultsIt was found that sample complexity significantly influenced the performance of the segment scan method. In metabolically complex samples such as feces and urine, the method yielded a substantial increase (up to 94 %) in detected peak pairs or metabolites, compared to conventional full scan. Conversely, less complex samples like saliva exhibited more modest gains (approximately 25 %). Based on the observations, a 120-m/z segment scan method was determined as a routine approach for CIL LC-Orbitrap-MS-based metabolomics with good compatibility with different types of biological samples. For this method, a further investigation on relative quantification accuracy was done. The peak area ratios of 12C-/13-labeled metabolites were slightly reduced with 72%–84 % of peak pairs falling within the ±25 % range of the anticipated peak ratio of 1.0 among different samples, as opposed to 81%–90 % in the full scan, which was attributed to the inclusion of more low-abundance peak pairs within the narrow MS segments. However, the overall peak ratio measurement precision was not significantly affected by the segment scan. Significance and noveltyThe segment scan method was found to be useful for CIL LC-Orbitrap-MS-based metabolome analysis of different types of samples with significant improvement in metabolite detectability (25–94 % increase), compared to the conventional full scan method.

Time modulation to manage and increase the power harvested from external vibrations

We investigate how a single resonator with a time-modulated component extracts power from an external ambient source. The collected power is largely dependent on the precise modulation signal frequency choice. We focus on the power absorbed from external vibration using a mechanical resonator and how time modulation of the damper can make a significant difference in the amount of harvested power, leading to more than 10 times enhancement compared to an analogous system without time modulation. We also find that a narrow band pair of peak and dip in the spectrum of the absorbed power occurs because of the presence of an exceptional point of degeneracy (EPD). In this narrow frequency range, the delay between the damper modulating signal and the external vibrating signal largely affects the collected power. The high frequency-selectivity of EPD-induced power management could potentially be used in sensing and spectrometer applications.

Quality guided reversible data hiding with contrast enhancement

Reversible data hiding with contrast enhancement (RDH-CE) enables contrast enhancement of the image and lossless recovery of host image after embedded data extraction. Although the current RDH-CE methods are effective in enhancing carrier images and ensuring reversibility, image quality control is still lacking, which may lead to poor image visualization. In more serious situations, the image detail information may be lost. The peak pair selection mechanism plays an extremely crucial role in image quality enhancement; however, existing work often neglects this. In this paper, we propose an RDH-CE algorithm that pursues high image quality maintenance, aiming to maintain image quality by guiding and controlling the selection of peaks and the direction of histogram shift through quality metrics. Specifically, instead of simply selecting only one pair of peaks at each peak selection stage, our algorithm selects several pairs of peaks that meet the requirements as candidate peak pairs. It then first performs simulated histogram equalization on these candidate peaks, followed by analyzing the situation of the quality metrics generated by each pair of peaks accordingly, and then selects the optimal peaks for the current iteration based on the performance of each pair of candidate peaks to be used in the equalization process. Our selection mechanism also dynamically changes the peak selection strategy based on before-and-after changes in the actual metrics, which can better ensure image quality stability over the iterations. Under the evaluations of a series of image quality metrics, the proposed method can still maintain high quality and visual effect under high iteration and has strong stability for image quality control, thus demonstrating the effectiveness and superiority of the proposed method.

Gold nanorods and tungsten disulfide nanocomposite modified electrode for hemoglobin electrochemical biosensing of trichloroacetic acid and nitrite

In this paper, gold nanorods (AuNRs) and tungsten disulfide (WS2) nanocomposite was prepared and modified on the carbon ionic liquid electrode (CILE) surface. Hemoglobin (Hb) was further immobilized on the electrode surface to fabricate a novel modified electrode (Nafion/Hb/AuNRs-WS2/CILE), which exhibited high conductivity and good biocompatibility. The electrochemical behaviors of Hb on the modified electrode were investigated with the appearance of a pair of well-shaped redox peaks, which may be ascribed to direct electron transfer of Hb Fe(III)/Fe(II) redox center. Besides, Nafion/Hb/AuNRs-WS2/CILE showed excellent electrocatalytic activity to the reduction of trichloroacetic acid and nitrite with a wide linear range, and the low detection limit could be obtained as 1.0 mmol/L and 0.33 mmol/L, which extended the application of AuNRs-WS2 nanocomposite in the field of bioelectrochemistry and electrochemical biosensors.