Optimal Measurement Conditions Research Articles

Gold Nanoframe Array Electrode for Straightforward Detection of Hydrogen Peroxide

The nanostructuring of a sensing membrane is performed through colloidal nanosphere lithography (NSL) techniques with a tiny polystyrene nanobead template 100 nm in size. The solvent ratio adjustment has been proven to be effective in assisting the monolayer deposition of small templating particles with minimal defects. Two distinct structures, namely, a billowy gold nanostructure (BGN) where the nanobead template is left unetched and a gold nanoframe array (GNA) with a regular ring-like structure after template removal, are used for the extended-gate field-effect transistor (EGFET) electrodes. The GNA structure generates an electroactive surface area significantly (~20%) larger than its geometrical area as well as a greater surface roughness than the BGN. When integrated with the portable constant voltage–constant current (CVCC) FET circuitry for pH screening to determine the optimized measurement conditions for H2O2 sensing, the GNA sensing membrane also shows more improved Nernstian sensitivity at ~50 mV/pH than the BGN electrode. The more optimized sensitivity is then proven using the GNA in the detection of H2O2, the most common representative reactive oxygen species (ROS) involved in the environment, food, and neurodegenerative diseases, such as Parkinson´s and Alzheimer´s diseases. The GNA electrode has a sensitivity of 70.42 mV/log µM [H2O2] and a limit of detection (LoD) of 1.183 µM H2O2. The integrated ion sensing system employing unique, highly ordered gold array gate electrodes and a portable CVCC circuit system has shown a stable real-time output voltage signal, representing an alternative to bulky conventional FET devices for potential on-site H2O2 detection.

Differential Pulse Voltammetry Technique Using Ferrocene-Modified Carbon Paste Electrodes for Determination of Pb(II) In Kepok Banana

The voltammetry method is a field of electrochemistry that measures electric current at a certain potential, which can be used to determine the concentration of inorganic and organic compounds that can be oxidized or reduced. In this research, the differential pulse voltammetry (DPV) technique has been used to determine the content of Pb(II). The carbon paste electrode (CPE) and ferrocene-modified carbon paste electrode (CPE-Fc) were used as working electrodes. This study aims to improve the sensitivity of Pb(II) measurement. Two parameters were optimized were ferrocene composition and scan rate. The validation parameters involved the linear concentration range, detection limit, quantization limit, precision and accuracy. The optimum ferrocene composition was found at 6%, and scan rate was 15 mV/s using CPE, increase to 20 mV/s using CPE-Fc. The validation results showed the linearity using CPE-Fc wider than CPE at the peak potential of 0.515 V. The detection and quantization limit values using CPE were 0.1551 µg/L and 0.1556 µg/L, and down to 0.1089 µg/L and 0.1090 µg/L using CPE-Fc. The precision determination for both of CPE and CPE-Fc had good results, indicated by the Horwitz ratio less than two. Percentage of recovery using CPE-Fc of 85.59 8.18%. CPE-Fc at the optimum measurement conditions was used to determine the levels of Pb(II) in kepok banana, and the result was obtained 4.4306 0.0009 mg/kg. The level of Pb content was found to exceed the established threshold based on Standard National Indonesia (ISN) No. 7387:2009 which is 0.5 mg/kg.

Non-exponential magnetic relaxation in magnetic nanoparticles for hyperthermia

Magnetic nanoparticle based hyperthermia emerged as a potential tool for treating malignant tumours. The efficiency of the method relies heavily on the knowledge of magnetic properties of the samples; in particular, knowledge of the frequency dependent complex magnetic susceptibility is vital to optimize the irradiation conditions and to provide feedback for material science developments. We study the frequency-dependent magnetic susceptibility of an aqueous ferrite suspension for the first time using non-resonant and resonant radiofrequency reflectometry. We identify the optimal measurement conditions using a standard solenoid coil, which is capable of providing the complex magnetic susceptibility up to 150 MHz. The result matches those obtained from a radiofrequency resonator for a few discrete frequencies. The agreement between the two different methods validates our approach. Surprisingly, the dynamic magnetic susceptibility cannot be explained by an exponential magnetic relaxation behavior even when we consider a particle size-dependent distribution of the relaxation parameter.

Optimization of in-line near-infrared measurement for practical real time monitoring of coating weight gain using design of experiments

This study was conducted to develop an in-line near-infrared (NIR) spectroscopy approach that allows real time quantitative analysis of the coating weight gain on a moving tablet surface during a coating process where talc is used. A holder directly inserting a diffuse reflectance probe into a coating pan was designed, and the optimal measurement conditions were identified using the design of experiments (DoE). The surface of the probe was kept clean of coating droplets at a maximum distance between the probe and the holder of 272.5 mm, leading to the acquisition of accurate spectral data. Under this condition, partial least squares regression (PLSR) was developed using the spectra from 7197 to 6233 cm−1, which covers the specific peaks for the core tablet and the coating solution. Under the same conditions, least squares regression (LSR) was developed using the univariate predictive analysis of the single absorption spectrum of talc at 7181 cm−1. In a comparison of the accuracy of the two models, PLSR was found to be more accurate as a result of testing the significance of differences between these distributions in terms of the root mean square errors of prediction (RMSEP) using a randomization t-test. Additionally, it confirmed that the predicted weight gain using NIR spectroscopy was correlated with the coating thickness measured using micro-CT. In conclusion, this study developed an in-line NIR measurement approach for the real-time monitoring of the coating weight gain of tablets and optimized the conditions by evaluating the effect of various factors.

An Audio Distortion Dynamic Range Index for Evaluating the Performance of Audio Systems

The dynamic range (DR) index lacking of an official definition leads to ambiguities in performance evaluation. The existing measurement methods of DR do not always match with the various actual application conditions, and some detailed distortion behavior of the device under test (DUT) is not extracted. In this paper, a new index for evaluating the DR performance of audio systems is proposed and validated, herein referred to as the audio distortion dynamic range (ADDR). It reduces the uncertainty of measurement conditions by an explicit definition and unifies the signal-to-noise ratio (SNR) and the signal-to-noise-and-distortion ratio (SINAD) indexes if under the same measurement condition. Moreover, to comprehensively reflect the impact of harmonic, spurious, and noise components on the DUT, the definitions of the traditional indexes based on classification of distorted components are replaced by the variable thresholds in the ADDR definition. Subsequently, the detailed steps of ADDR and the critical factors influencing its accuracy, are analyzed and then the optimized measurement conditions are given. Experiments based on simulated DUTs show the ADDR index can distinguish performance difference that the traditional indexes cannot distinguish, which proves it is an effective supplementary to the existing indexes in some real applications.

The role of the spectral matrix effect in the element analysis of biological fluids in ICP-MS

Elements in whole blood and urine were determined, and the influence of matrix spectral interference on the analysis results was evaluated in search of optimal measurement conditions on the quadrupole mass spectrometer with inductively coupled plasma Agilent 7700 that did not require correction when determining the varied elements in physical properties. The study showed that when using a quadrupole mass spectrometer, the detection limit of gallium in the studied biological fluids (both whole blood and urine) will be determined not by the background content of the element, but by the interfering effect of ions formed by the matrix components of the analyzed samples.

Instrumental texture analysis on the surface of dry-cured ham to define the end of the process

The end of the elaboration process of dry-cured ham is currently decided by product weight loss and/or by an expert who carries out an evaluation of the tactile texture on the surface. The objective of this study was to define the optimal measurement conditions of an instrumental texture analysis on the surface of the dry-cured ham (ITAS), to define the end of process. 120 dry-cured hams were classified by experts into Hard (appropriate) or Soft (non-appropriate) texture groups and used to perform compression tests using different probes on three anatomical positions. Results showed that the small probe in position 2 gave the most discriminant conditions, providing representative information of the internal texture. Although classification using only weight loss was possible with an accuracy rate of 80.4% or 66.7% depending on the weight loss, the maximum classification accuracy was obtained when using ITAS in combination with weight loss. Further studies at industrial level are needed.

Indirect differential pulse voltammetric analysis of cyanide at porous copper based metal organic framework modified carbon paste electrode: Application to different water samples

Carbon paste electrode (CPE) modified with porous copper based metal organic framework (Cu-MOF) nanocomposite is described for analysis of cyanide (CN−) for the first time. The electrochemical performance of the proposed electrode was investigated by differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The Cu-MOF nanocomposite was characterized using scanning electron microscope (SEM), N2-adsorption-desorption isotherms, powder X-ray powder diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Under optimal conditions of measurements, the anodic peak (Ipa) decreases linearly in the range of 1.87–25 μM with LOD of 0.60 μM (at S/N = 3). The Cu-MOF/CPE showed good selectivity towards CN− measurement with no significant interference in pH 7.0 using 0.25 M KCl to increase the medium conductivity and to stabilize the analyte and prevents its volatility. Moreover, the method was successfully applied for determination of CN− in different environmental water samples.

Novel approach to the measurement of antithyroglobulin antibodies in human serum – application of the quartz crystal microbalance sensors

Measurement of antithyroglobulin antibodies (TgAb) is an inevitable laboratory tool in the management of thyroid gland diseases. Currently available immunoassays still have limitations underlying the necessity of the introduction of fast, sensitive, and label-free technologies. Our aim was to develop a method for TgAb measurement in human serum based on the quartz crystal microbalance (QCM) technology. We immobilized thyroglobulin on the surface of Attana LNB Carboxyl sensor chip®, prepared standard curve covering the range of 1–50000 kIU/L, and established optimal measurement conditions. The validation included determination of the detection limit (LOD), functional sensitivity, linearity, precision, as well as the comparison with the results of the radioimmunoassay (RIA). The LOD and functional sensitivity were 4.2 kIU/L and 4.7 kIU/L, respectively. The method was linear in the range of 20–10000 kIU/L. The regression equation for comparison with RIA was CQCM= 1.0056 • CRIA– 24.2778, whereby no significant proportional or systematic difference was present. There was a good agreement with RIA in the classification of patients according to the clinical significance of the results. The developed method has advantages over currently available assays in terms of better LOQ, a higher upper limit of linearity, and precision.The characteristics of the developed method unambiguously show that the application of the QCM biosensors offers a highly reliable novel approach for the measurement of TgAb in human serum.

Wideband microwave multiport-based system for low gas concentration sensing and its application for acetone detection

A microwave system dedicated to low gas concentrations sensing at room temperature is proposed. An optimized transmission line type sensor coated with a thin film, that changes electrical properties under target gas exposure is developed. The sensor’s response, namely its reflection coefficient is measured using a novel wideband multiport reflectometer. The instrument exhibits an advantageous measurement uncertainty, which can be adjusted to precisely measure small reflection coefficient changes over a wide bandwidth. Broadband data is used to extract the system’s response to gas defined as the reflection coefficient’s phase slope over frequency. The developed sensor covered with acetone-sensitive copper-oxide film together with a reflectometer operating over 1.5 GHz – 4.5 GHz band were incorporated in a gas measurement system to test its response to low acetone concentrations in the range of 0.5 ppm – 5 ppm. Due to high sensor’s sensitivity, optimum measurement conditions provided by the dedicated reflectometer and wideband analysis of the collected data, a robust and low-noise signal proportional to acetone concentration is achieved. The tested concentrations result in measured system’s response in the range of 0.02°/GHz – 0.29°/GHz @ 20 °C and 50 % of relative humidity derived with uncertainty of ±0.022°/GHz being 3 times lower than for a commercial instrument. Additionally, humidity dependence, stability, repeatability, reproducibility, and selectivity are investigated.

Multisine impedimetric probing of biocatalytic reactions for label-free detection of DEFB1 gene: How to verify that your dog is not human?

Albert is a dog (Canis familiaris), but he does not realize this. Albert loves human food (and beer), watching movies on the internet, sleeping in bed, and more. But he should not do all these things. To convince him that, we have desinged a test procedure. The DEFB1 gene is unique to human species. Detecting its presence from saliva and in short periods may offer an advantage in the field of forensic medicine, and influence Albert’s bad habits.This study reveals novel utilization of the multisine impedance spectroscopy carried out during potentiodynamic polarization (pDEIS) of the electrode. We have utilized pDEIS to detect DEFB1 gene in collected saliva samples. The detection process was conducted at the boron-doped diamond surfaces functionalized with DEFB1-complimentary oligonucleotide sequence, anchored at the electrode surface. Next, a short-term electrode incubation in presence of target DNA sample allows for achieving DNA hybridization when exposed to human DNA material. The dsDNA orientation vs electrode surface is affected by polarization, and tracked by changes in the electrode kinetics preceded by subtle capacitance dispersion effects. The optimized measurement conditions range between +0.5 and +0.9 V vs Ag|AgCl due to nonspecific DNA adsorption, affecting heterogeneous charge transfer. The DNA hybridization is not achieved in the case of non-complimentary ssDNA originated from any other species subjected to this test. The discussed differences obtained during electrode incubation are supported by the XPS analyses.

Defect Detection and Degradation Analysis in Photovoltaic Modules using Thermography, Spectroscopy, and Current–Voltage Measurements, and Quantitative Assessment of Their Impact

The measurement of defects in photovoltaic (PV) module and their impact assessment can help to improve the reliability and performance of PV systems. Herein, improved defect detection and degradation analysis approach using the combination of infrared (IR) thermography, electroluminescence emission spectroscopy, and current–voltage (I–V) measurements are presented. Moreover, an image‐processing scheme to automatically detect and compute defective area is also proposed. First, experiments are conducted on normal operating modules. Subsequently, different defects and failures are induced, and experiments are conducted again. These modules are analyzed quantitatively and qualitatively. From IR images, defective area, overheating, and underheating computations are carried out. From I–V measurements, power losses, current degradation, and voltage degradation calculations are carried out. The defects that show up in IR images are correlated with I–V curve deviations and their effect on power losses and current/voltage degradation is also analyzed. Moreover, electroluminescence emissions of defective regions are correlated with overheating/underheating calculations. Finally, the observations from experimental results and related quantitative/qualitative computations are summarized. This approach can help to investigate module degradation stage and mode. It can also help in decision making with the use of only IR imaging and related computations in absence of optimum measurement conditions.

887-P: Development of the Noninvasive Diabetes Monitoring Method

Aims/Background: To prevent diabetic complications, strict glucose control and frequent monitoring of blood glucose levels with invasive methods are necessary. We considered monitoring of diabetes-related biomarkers in tears may be the possible methods for diabetes monitoring methods. Many studies about tear glucose levels have been reported and tear glucose levels correlate with blood glucose levels. This time, we focused on glycoalbumin (GA) levels, which reflect an average of blood glucose levels over the preceding 2 weeks, and studied the correlation between GA levels in blood and tears. Methods: We recruited 100 diabetic subjects and collected blood and tear samples. GA levels in blood were measured by an enzymatic method, and GA levels in tears were measured by Liquid Chromatography/Mass Spectrometry (LC-MS/MS). Results: The GA levels in tears of 99 out of 100 samples were appropriately measured by LC-MS/MS. GA levels in blood and tears were significantly correlated (P < 0.001). Multiple regression analysis revealed that this correlation was maintained even after adjustment for age, gender, nephropathy stage, and obesity (P < 0.001). Conclusions: GA in tears was the first measured diabetes-related biomarker. GA levels in tears were strongly correlated with those in blood, considering various factors. As GA value is a ratio, GA levels in tears were not thought to be influenced by dilution or concentration of tears and showed strong correlation with those in blood. From the above, GA in tears could be a diabetes-related biomarker that can be measured noninvasively. In the future, we plan to optimize measurement conditions, develop measurement equipment and verify the effectiveness and usefulness of this diabetes monitoring method. Disclosure M. Aihara: None. N. Kubota: None. T. Kadowaki: Research Support; Self; Astellas Pharma Inc., Daiichi Sankyo, Mitsubishi Tanabe Pharma Corporation, MSD Corporation, Novartis Pharma K.K., Novo Nordisk Pharma Ltd., Ono Pharmaceutical Co., Ltd., Sanofi, Sumitomo Dainippon Pharma Co., Ltd., Takeda Pharmaceutical Company Limited. Speaker’s Bureau; Self; Abbott, Astellas Pharma Inc., AstraZeneca K.K., Boehringer Ingelheim Pharmaceuticals, Inc., Cosmic Corporation, Daiichi Sankyo, Eli Lilly Japan K.K., FUJIFILM, Kowa Company, Ltd., Kyowa Hakko Kirin Co., Ltd., Medscape Education, Medtronic, Mitsubishi Tanabe Pharma Corporation, MSD Corporation, NIPRO Medical Corporation, Novartis Pharma K.K., Novo Nordisk Pharma Ltd., Ono Pharmaceutical Co., Ltd., Sanofi, Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited, Terumo Medical Corporation. Other Relationship; Self; Asahi Mutual Life Insurance.

Electrochemical Detection of Small Volumes of Glyphosate with Mass-Produced Non-Modified Gold Chips

Abstract Mass-produced printed circuit board (PCB) electrodes were used as electrochemical cells to detect the widely-used herbicide glyphosate. Square wave voltammetry (SWV) was used to determine the presence of glyphosate in aqueous Cu(NO3)2 solution. Optimal measurement conditions for the detection of glyphosate with PCB electrodes were found. It was determined that glyphosate was able to soak into the growing plants from the substrate. Glyphosate-contaminated plant juice was distinguished from control samples using the PCB electrode. Glyphosate-contaminated plants were found to have DNA mutations.

Experimental study on mercury content in flue gas of coal-fired units based on laser-induced breakdown spectroscopy

Accurate measurement of trace heavy metal mercury (Hg) in flue gas of coal-fired units is great significance for ecological and environmental protection. Mixed gas was used to simulate the actual flue gas of a power plant in this study. A laser-induced breakdown spectroscopy (LIBS) system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure, Hg concentration in mixed gas and delay time on Hg measurement. The experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise ratio. The Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed gas. The Hg signal intensity and signal to noise ratio decreased with the increase in delay time. According to the above results, the optimized measurement conditions can be determined. Different Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method respectively. The relative error of prediction of the test sample obtained by the internal standard method was within 11.11%. The relative error of prediction of the traditional calibration method was less than 14.54%. This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS.

Route of magnetoimpedance and domain walls dynamics optimization in Co-based microwires

The influence of post-processing (annealing and stress-annealing) on the magnetic softness, Giant magnetoimpedance (GMI) effect and domain wall dynamics of Fe3.6Co69.2Ni1B12.5Si11Mo1.5C1.2 glass-coated microwires is studied.As-prepared Co-rich glass-coated microwire presents linear hysteresis loops and rather higher magnetoimpedance ratio with double-peak magnetic field dependence, typical for materials with transverse magnetic anisotropy.Considerable magnetic hardening and transformation of linear hysteresis loop with low coercivity (Hc ≈ 4 A/m) into rectangular with Hc ≈ 90 A/m upon annealing without stress is observed. However, we observed remarkable MI effect improvement at certain annealing conditions.Stress-annealing of studied microwire allows considerable magnetoimpedance ratio and domain wall velocity increasing. Additionally, remanent magnetization growth and coercivity decrease are generally observed upon stress annealing. Frequency dependence of maximum GMI ratio for as-prepared and annealed samples is evaluated. The obtained frequency dependence of the maximum GMI ratio allows determination of the optimal GMI measurement conditions for each sample. The observed stress-induced anisotropy and related changes in magnetic properties are discussed considering the internal stresses relaxation and “back-stresses”.

Влияние продолжительности импульса и времени измерения переходного процесса на проявление низкочастотной дисперсии электромагнитных свойств земли в измерениях на акваториях с глубиной до 100 м

The purpose of the study is to define the influence of the pulse duration and the transient measurement time on the display of the low-frequency dispersion of the electromagnetic properties of the geological formations in the transient measurements by electric lines for marine waters not more than 100 m deep. The study has analyzed the transient signal change Δ U ( t ), finite difference Δ 2 U ( t ) and transforms P 1( t ) (the ratio of the above values) as functions of the pulse duration and transient measurement time. The analysis has been conducted with a probe consisting of a source (a horizontal grounded electric line (AB) 500 m long, and a receiver (a three-electrode electric line (MON) 500 m long). The signals calculated for the conducting medium have been compared with the ones calculated for the conducting medium with a conducting polariziable base. The conducting medium is associated with the marine water mass in the shelf areas up to 100 m deep and non-polarizable geological layers. The conducting polarizable base includes geological formations that are characterized with induced polarization. The registration of the base polarization has been realized by introducing frequency-dependent electrical resistivity with the Cole-Cole formula. The calculations show that the optimum condition for the investigation of the polarization process and polarization properties of the geological environment covered with the water mass, is the use of longer-lasting pulses and signal registration till large time values. The optimum measurement condition is inducing the transient process with the pulses with the duration of not less than 4 s, and registering the signal for not less than 4 s. During the practical measurements taking place when towing the probe, the pulse duration and measurement time influence the number of the measured transients in a unit of the profile line length. Correspondingly, the pulse duration and measurement time have to be limited in order to enhance the possibility of the statistical enhancing of the useful signal. At the same time, these limitations should allow registering the display of the galvanic-induced polarization process in the general signal. The induced-polarization signal becomes predominating in the transient at later stages.

Current Measurement and Electrochemical Characterization of Gas Evolution Reactions on a Rotating Ring-Disk Electrode

The behavior of bubbles on a rotating ring-disk electrode (RRDE) during water electrolysis has been investigated as fundamental study to evaluate gas evolution reaction electrode activity. The gas evolved on the surface of the electrode reduced the active surface area and increased the overpotential for electrolysis. We investigated how the shape of the electrode affects the bubble behavior and how to obtain an optimal non-blockage electrode surface using a Pt rotating ring disk electrode (RRDE). Standard deviation (SD) of the electrolysis currents was obtained. The value of the SD is corelated with the bubble detachment phenomenon. We found that the rotation induced flux field removes the generated bubble with decrease of the SD. So, a larger SD indicates the bubble accumulation on the electrode surface, and the surface stranding in the gas film. The ring electrode showed higher current with smaller SD than disk electrode at an overpotential for both oxygen and hydrogen evolution reaction. Therefore, a ring electrode is better than a disk electrode to evaluate gas evolution reaction. The optimum current measurement condition is using ring electrode under rotation speed higher than 2500 rpm, because dependence of current and the SD on rotating speed was small enough. Under this condition, HER at − 0.1 V, the ring electrode delivers − 260 mA cm−2, and the disk delivers − 160 mA cm−2. For OER at 2.2 V, the ring electrode delivers 195 mA cm−2, and the disk electrode delivers 130 mA cm−2. The ring electrode capture about 35% more current than disk, which might be loss by the effect of the bubble blockage. In order to get better current measurement in a gas evolution reaction, using ring electrode to remove the bubbles from the electrode surface in a high rotation speed is recommended.

Post Mortem and Operando XPEEM: a Surface-Sensitive Tool for Studying Single Particles in Li-Ion Battery Composite Electrodes

X-ray photoemission electron microscopy (XPEEM), with its excellent spatial resolution, is a well-suited technique for elucidating the complex electrode-electrolyte interface reactions in Li-ion batteries. It provides element-specific contrast images that allows the study of the surface morphology and the identification of the various components of the composite electrode. It also enables the acquisition of local X-ray absorption spectra (XAS) on single particles of the electrode, such as the C and O K-edges to track the stability of carbonate-based electrolytes, F K-edge to study the electrolyte salt and binder stability, and the transition metal L-edges to gain insights into the oxidation/reduction processes of positive and negative active materials. Here we discuss the optimal measurement conditions for XPEEM studies of Li-ion battery systems, including (i) electrode preparation through mechanical pressing to reduce surface roughness for improved spatial resolution; (ii) corrections of the XAS spectra at the C K-edge to remove the carbon signal contribution originating from the X-ray optics; and (iii) procedures for minimizing the effect of beam damage. Examples from our recent work are provided to demonstrate the strength of XPEEM to solve challenging interface reaction mechanisms via post mortem measurements. Finally, we present a first XPEEM cell dedicated to operando/in situ experiments in all-solid-state batteries. Representative measurements were carried out on a graphite electrode cycled with LiI-incorporated sulfide-based electrolyte. This measurement demonstrates the strong competitive reactions between the lithiated graphite surface and the Li2O formation caused by the reaction of the intercalated lithium with the residual oxygen in the vacuum chamber. Moreover, we show the versatility of the operando XPEEM cell to investigate other active materials, for example, Li4Ti5O12.

Rapid determination of marbofloxacin by surface-enhanced Raman spectroscopy of silver nanoparticles modified by β-cyclodextrin

A novel surface enhanced-Raman spectroscopy (SERS) assay for marbofloxacin was developed based on β-cyclodextrin-modified silver nanoparticles (β-CD-AgNPs). The marbofloxacin could interact with β-CD-AgNPs and a new assembly was formed by AgN covalent bond. This assembly was characterized by the spectra of FT-IR and UV-vis. The optimal measurement conditions were studied in detail. In 0.033molL-1 HCl solution, marbofloxacin had a sensitive SERS signal at 806cm-1. The enhancement factor (EF) was 2.11×107. There was a good linear correlation between the concentration of marbofloxacin and SERS intensity: the linear range was 0.003-0.03μmolL-1 (r2=0.996). The limit of detection (LOD) (S/N=3) was 1.7nmolL-1 (S/N=3). Moreover, the influence of some interferences including Cu2+, K+, Zn2+, Ca2+, Na+, Mg2+, glucose and tiamulin on the determination were studied. The developed SERS method was used to detect the content of marbofloxacin in chicken and duck, the recovery was 101.3%-103.1% with RSD 4.07%-6.83%.