High Sensitivity Research Articles

A high sensitivity and wide frequency band vector hydrophone using PZT-based four spiral beam structure

The utilization of a high sensitivity and wide frequency band vector hydrophone exhibits significant potential in the exploration of underwater target. However, enhancing these performance remains a challenge due to limitations in materials and structures. Herein, we report a micro-electro-mechanical system (MEMS) vector hydrophone (FSPVH) built on lead zirconate titanate (PZT) film with four spiral beam structure and polyamide (PA) microsphere. The optimization of the structural dimensions and PZT thin film distribution has been the result of simulation. The FSPVH have been fabricated using MEMS technology, and the prototype has been assembled. The FSPVH was tested in a standing bucket wave calibration system. The results show that FSPVH achieve a sensitivity of −181.5 dB (0 dB = 1 V/μPa) at 1100 Hz, and the work bandwidth is 20–1330 Hz. Meanwhile, it exhibits a satisfactory “8″ shape directivity. This work provide theory and technique supports of vector hydrophone with high sensitivity and wide frequency band.

High sensitivity and detectivity of anomalous Hall sensor based on coupled magnetic bilayers

Detection of ultralow magnetic field requires a magnetic sensor with high sensitivity and a low noise level. In this work, we used the Co20Fe60B20/Ti/Co20Fe60B20 magnetically coupled multilayer as the core structure of an anomalous Hall sensor. We adjusted the thickness of the Ti interlayer to modify its perpendicular magnetic anisotropy and interlayer magnetic coupling, thereby improving the sensitivity of the anomalous Hall sensor. Through the investigation of magnetic field response and noise properties of devices with different Ti thicknesses, the highest sensitivity of 34 803 Ω/T and the best magnetic field detectivity of 4.6 nT/Hz at 1 Hz were achieved with a Ti thickness of 2.0 nm at room temperature. This anomalous Hall sensor has both ultrahigh sensitivity and magnetic field detectivity, making it a good candidate for applications in detecting weak magnetic fields.

A Fluorescent Probe for Hydrazine Based on 4-hydroxycoumarin with High Selectivity and Sensitivity

Background: Therefore, the development of reliable analytical techniques with high selectivity and sensitivity to detect hydrazine is required for the protection of human health and safety. Objectives: Traditional methods for detecting N2H4 are frequently time-consuming, less accurate, and unsuitable for the analysis of living systems. Numerous fluorescent probes for hydrazine have been produced and gained some valuable results recently. The creation of a simple fluorescent probe for hydrazine detection is the goal of this project Method: In this study, 300 µL of probe 3-methyl-2-oxo-2H-chromen-7-yl propionate (MOCP) was mixed with an equivalent amount of the solution of each analyte to obtain the measurement solution. Following a 10-minute room temperature incubation period, the fluorescence spectra of the resultant solution were recorded. Results: The fluorescence intensity of the probe was noticeably enhanced when N2H4 was added to the probe, but almost no fluorescence enhancement was observed when other competitive ions were added. Conclusion: A hydrazine fluorescent probe based on 4-hydroxycoumarin fluorophore was developed. The probe MOCP displayed high sensitivity and selectivity for hydrazine, with a color change from colourless to blue for detection by the naked eye. Moreover, it demonstrated a low detection limit of 20 nM and a fast reaction time of 30 s.

Validation of Metallothionein Immunohistochemistry as a Highly Sensitive Screening Test for Wilson Disease

Wilson’s disease (WD) is a rare autosomal recessive condition with protean clinical manifestations that results from biallelic ATP7B mutations. However, non-destructive tissue tests to be applied clinically to tissue specimens are not widely available to effectively assess patients for possible WD. Previously, we showed that metallothionein (MTH) immunohistochemistry has a high sensitivity and specificity for WD diagnosis and, thus, represents a potentially powerful diagnostic tool that can be used in routine histologic sections. We sought to validate this finding in a large cohort of bona fide WD patients and to correlate metallothionein expression with other histologic features.We identified 91 cases of WD, which included 28 needle biopsies and 64 explants from 14 centers worldwide. Histologic features were evaluated, and a histopathological pattern was assigned to each case. All cases were evaluated with Masson trichrome and MTH immunohistochemistry (clone UC1MT, Abcam) using previously published technique. Liver tissues from chronic cholestatic diseases (n= 42) were used as controls.The median age of the cohort was 28.5 years. Out of 91 total cases, 83 were positive for MTH immunostain. In the controls, all 42 cases were negative for MTH immunostain. The sensitivity and specificity of MTH immunostain for WD were 91.20% and 100%, respectively.MTH immunohistochemistry is a highly sensitive and specific cost-effective screening tool for WD. It can be used for patients across age groups, varied histologic patterns, and fibrosis stages. This marker could prove to be a valuable tool in the evaluation of patients with possible WD.

Determining the carbon detection limit with magnetic sector dynamic Secondary Ion Mass Spectrometry (SIMS)

Dynamic SIMS is often used to evaluate the concentration of impurities in solids because of its high sensitivity, depth profiling capabilities, good depth resolution, and high throughput. Continuous ion beam sputtering with a high-density primary beam provides high sensitivity and reduces the background contribution from residual gases within the analytical chamber. Dynamic SIMS experiments performed with several magnetic sector instruments using various sputtering rate conditions demonstrated a slow decrease of the carbon detection limit with the increase of sputtering rate (SR), when it was varied by changing the sputtering beam density. The dependence data, within the scatter limits, can be fit by a power function of SR with the exponent of about -1/2. The observed detection-limit-dependence curve is common for magnetic sector SIMS instruments, owing to contamination and the design of the analytical chamber. The depth resolution of light-element SIMS analysis (except for oxygen) performed using Cs+ sputtering is limited and cannot be improved by reducing the impact energy of the sputtering beam. A segregation-type depth profile with a long trailing edge was observed in the B, C, and N depth profiles when Cs+ sputtering was employed under ultra-high vacuum conditions. This effect is plausibly associated with preferential sputtering owing to the difference in the surface binding energy, along with the large difference in the mass of the interacting atoms within the collision cascade during sputtering. The depth resolution improved with surface oxidation when Cs+ sputtering was combined with backfilling of the analytical chamber using O2. The analytical chamber backfilled with oxygen can be sufficiently replaced with a very low-impact energy-focused oxygen beam, enabling simultaneous oxygen and cesium co-sputtering SIMS analysis. The practical feasibility of using a co-sputtering with focused Cs+ and O2+ sputtering beams to achieve a high depth-resolution for carbon analysis under ultrahigh vacuum conditions was demonstrated.

A ZnO-nanorod/PEDOT:PSS nanocomposite functionalized bridge-like membrane type nanomechanical sensing device for ultrasensitive blood lead detection

Lead (Pb) ion detection poses a critical problem, particularly in environmental monitoring, industrial operations, and public health, especially for young children and expecting women. Determining lead levels in blood early on is essential to minimizing the long-term consequences of lead exposure. Several sophisticated detection instruments, such as mass spectrometers which perform with high sensitivity, specificity and accuracy, but require a lab-based setting, multi-step sample preparation, expensive payment and professional operation. It is evident that a highly sensitive, portable, low-cost, quick sample-to-result, blood lead detection device that can be tested at the point-of-care is necessary. Consequently, we developed a unique ZnO/PEDOT:PSS nanocomposite layer integrated with a CMOS MEMS-based bridge-like membrane-type (BM) nanomechanical sensor for detecting lead levels in blood. PEDOT:PSS was combined with ZnO nanorods to increase lead ion binding. The sensor responds seven times better to lead ions using nanorods in the detecting layer. A linear resistance change rate response was found from 0.005 to 10 ppm, with the limit of detection (LOD) of 0.12 ppb. Similarly, our BM nanomechanical sensor can correctly assess Pb2+ in human serum with recovery rates of 86.25-150%. Measurements of human blood samples from patients with varying lead ion concentrations validated by the standard AAS show a good linear connection with the BM nanomechanical sensors' concentration, with a regression coefficient of 0.92. This describes the first micromachined nanoachanical sensing system for detection of Pb2+ in only 5 μL of human serum sample. The device achieves a time-to-result of less than 10 min. The system is designed to be very sensitive and offers affordable, disposable sensing chips together with a portable signal acquisition platform.

Enhanced ammonia sensing performance of NiFe2O4 and dysprosium doped NiFe2O4 for advanced Environmental Monitoring

Air pollution driven by rapid technological growth, has heightened mortality rates and infectious diseases, prompting research into advanced gas-sensing materials. This study examined the gas sensing properties of NiFe2O4 and dysprosium-doped NixDy1-xFe2O4 (x = 0.02, 0.04, 0.06) under ammonia concentrations of 10–100 ppm. The incorporation of Ni2+ ions into the Fe2O4 lattice revealed p-type semiconductor behaviour. Notably, NixDy1-xFe2O4 (x = 0.06) exhibited superior ammonia sensing, with high sensitivity and excellent selectivity. Stability tests confirmed its robustness, maintaining 83.8 % of its initial response, highlighting its potential for effective ammonia detection.

CMOS-Compatible MEMS 2D Thermal Flow Sensor With High Sensitivity and Low Power Consumption

CMOS-Compatible MEMS 2D Thermal Flow Sensor With High Sensitivity and Low Power Consumption

Multi-site DNA methylation alterations of peripheral blood mononuclear cells serve as novel biomarkers for the diagnosis of AIS/stage I lung adenocarcinoma: A multi-center cohort study.

Early diagnosis remains an obstacle for improving the outcome of lung adenocarcinoma (LUAD). DNA methylation changes in peripheral blood mononuclear cells (PBMCs) could reflect immune response to tumorigenesis, providing the theoretical basis for early cancer diagnosis based on immune cell profiling. This multi-center study evaluated the DNA methylation patterns based on PBMCs samples from 1115 individuals at nine medical centers. Genome-wide DNA methylation profiling of PBMCs in a discovery cohort (35 LUAD patients and 50 healthy controls) was performed using Illumina 850K microarray. Candidate differentially methylated CpG positions (DMPs) were selected and validated in a two-step DMPs screening cohort (65 LUAD patients and 80 healthy controls) by pyrosequencing and multiple target region methylation enrichment sequencing (MTRMES). Then, an early LUAD Diagnostic Panel (LDP score) based on multi-site methylation-specific chip-based digital PCR was constructed in a training set and then confirmed in a validation set from the LDP score development cohort (389 AIS/stage I LUAD patients and 293 healthy controls). Besides, we included 157 other cancer patients, including 52 gastric cancer (GC) patients, 50 breast cancer (BC) patients, and 55 colorectal cancer (CRC) patients to assess the specificity of LDP score. In addition, we also evaluated the early warning ability of LDP score for LUAD in a prospective cohort (46 people who were at high-risk of developing LC). A total of 1415 LUAD-specific DMPs were identified. Then, six DMPs were selected for validation and three DMPs were finally verified. The LDP score was constructed by combining the three DMPs, age, and gender, and showed an AUC of 0.916, sensitivity of 88.17%, and specificity of 80.20% in combined set, outperforming traditional methods, such as CEA and CT (detection rate: 87.79% vs. 4.69%; 87.79% vs. 35.21%). This diagnostic performance was confirmed in sub-types of LUAD with clinical challenges, such as 6-20mm LUAD (AUC: 0.914, 95%CI: 0.889-0.934) and ground-glass nodules (AUC: 0.916, 95%CI: 0.889-0.938). Importantly, our LDP score had significant improvement in terms of selecting high-risk individuals who should receive low-dose computed tomography (87.80% vs. 9.28%). Remarkably, LDP score could predict LUAD around two years before clinical diagnosis in our prospective cohort. The novel developed LDP score represented a convenient and effective assay for the detection of AIS/stage I LUAD with high sensitivity and specificity, and had demonstrated unique advantages over traditional detection methods.

Assembly of Fe@Zn-Coordination Polymer Composite: Iron Doping Foster the Luminescent Detection for Tetracycline, Uric Acid and Cr2O72− and Crystal Violet Degradation Efficiency

Coordination polymers exhibit a diverse array of applications across various fields, and through the development of composite materials, their utility and versatility are further enhanced, broadening their impact on our world. In this work We synthesized the first coordination polymer (CP) based on Zn and doped with Fe composites (Fe@Zn-CP Composite), which exhibit enhanced photocatalytic activity triggered by visible light. Using mixed ligands orotic acid potassium salt, 1,3 di (4-pyridyl) propane (dpp), and FeSO4 in a simple method at ambient temperature, the Zn-CP [Zn8(Or)8(dpp)4(H2O)8] was resynthesized here to form the Fe@Zn-CP composites. Zn-CP and Fe@Zn-CP Composite were both characterized by powder X-ray diffraction, FT-IR spectra analysis, and SEM-EDX analysis and elemental mapping analysis. It has been observed that Fe@Zn-CP Composite is as multi-functional luminescence sensor for MnO4−, Cr2O72− and Tetracycline with high sensitivity. In-depth research has also been done on the recyclable nature, and photocatalytic efficiency of Zn-CP and Fe@Zn-CP Composite for the decomposition of organic dyes Crystal Violet and Rose Bengal (RB) in contaminated water under the sunlight irradiation.

Ultra-sensitive low-temperature luminescent thermometry based on Boltzmann behavior of the Stark sub-levels of Pr3+

The cryogenic sensor is critical for numerous applications such as cryobiology, aerospace space probes, and solid-state superconducting quantum technology. However, it is still a challenge to operate at temperatures below 100K using luminescent intensity ratio (LIR) thermometers with typical thermal coupling levels based on the Boltzmann mechanism. In this work, a sensitive low-temperature luminescence thermometry approach has been developed utilizing Boltzmann behavior of the Stark sub-levels of Pr3+. Spectral Stark-splitting feature of the 1D2 multiplet of Pr3+ was observed in CaNb2O6: Pr3+ phosphor, and the luminescence intensity ratio (LIR) of high state (Stark sub-level (2)) and low state (Stark sub-level (0)) of 1D2 was employed for temperature sensing, resulting in a notable relative sensitivity (Sr) of 11.3% K−1 at 60K. In addition, the intervalence charge transfer (IVCT)-based strategy improves the temperature sensitivity above room temperature with maximum Sr up to 1.54% K−1 at 420K. This work consistently demonstrate high sensitivity at low temperature, indicating potential applications in cryogenic temperature sensor. These results provide a route to the development of luminescent thermometers with a high sensitivity at low temperatures and a wide range of operating temperatures.

Development and Evaluation of a Semi-Nested PCR Method Based on the 18S ribosomal RNA Gene for the Detection of Babesia aktasi Infections in Goats

We developed and evaluated a semi-nested PCR assay for the detection of Babesia aktasi infection in goats based on the sequence of the B. aktasi 18S ribosomal RNA gene. Following in silico screening, the specificity of the primers was assessed using reference DNA samples, including B. ovis, B. motasi, B. crassa, B. venatorum, B. divergens, B. capreoli, Theileria ovis, and T. annulata. To determine the sensitivity of the method, blood infected with 2% parasitemia of B. aktasi was diluted to 10-fold serial dilutions. The method specifically amplified a 438 bp fragment of B. aktasi DNA, but did not demonstrate cross-amplification with the other hemoparasites tested. The sensitivity assay indicated that this PCR method was able to detect infection at a dilution of 10−8 of 2% parasitemia (0.074 parasites/200 µL). Ninety-seven blood samples collected from goats were used to analyze for B. aktasi, and the infection was detected in 18.5% of the goats. Additionally, the method was also applied to 44 field DNA samples that were detected to be positive for B. aktasi by reverse line blotting (RLB), and showed 84.1% agreement. The findings revealed that newly developed semi-nested PCR can detect B. aktasi infections in goats with high sensitivity and specificity.

Diagnostic accuracy of point-of-care ultrasound (PoCUS) for the diagnosis of hip effusion in the pediatric emergency department.

A new limp or refusal to weight-bear are common symptoms in children presenting to the pediatric emergency department (ED). This poses a diagnostic challenge, particularly among toddlers and nonverbal patients. Point-of-care ultrasound (PoCUS) used by pediatric emergency medicine physicians may detect hip effusion, which dramatically aids diagnostic workup and management. There is limited literature regarding the accuracy of hip PoCUS conducted by pediatric emergency medicine physicians. This study aims to assess the diagnostic performance of pediatric emergency medicine physician-performed PoCUS in identifying hip effusion. This prospective study was conducted in a single-center pediatric ED. Children presenting with limb pain or new limp were evaluated by pediatric emergency medicine physicians who also performed hip PoCUS and categorized findings as either "effusion" or "no effusion" based on standard sonographic definitions. Patients also underwent radiology department ultrasound reviewed by a pediatric radiologist. Diagnostic test characteristics with corresponding 95% confidence intervals (CI) were calculated using radiology department ultrasound findings as the reference standard. A total of 95 patients were enrolled by 8 pediatric emergency medicine physicians. Excellent agreement was observed between PoCUS performed by pediatric emergency medicine physicians and radiology department ultrasound for the presence or absence of hip effusion (kappa = 0.81 [95% CI 0.70-0.93]). Hip effusion was identified by PoCUS in 44 out of 49 effusion-positive patients, with a sensitivity of 89.8% (95% CI 77.7-96.6%), specificity of 91.3% (95% CI 79.2%-97.5%), positive likelihood ratio of 10.33 (95% CI 4.03-26.47), and negative likelihood ratio of 0.11 (95% CI 0.05-0.26). PoCUS performed by pediatric emergency medicine physicians has reasonably high sensitivity and specificity for diagnosing hip effusion among pediatric patients presenting to the pediatric ED with a limp or leg pain. This practice may potentially expedite both diagnosis and treatment within this patient population.

Validation of Manipal Bedside Swallowing Screening Test for Assessing Aspiration in Individuals with Tracheostomy.

To validate the Manipal Bedside Swallowing Screening Test (MBSST) for assessing aspiration in individuals with tracheostomy using Video Fluoroscopic Swallow Study (VFSS). A total of 53 tracheostomized participants were screened for aspiration at bedside and VFSS across different consistencies. Penetration Aspiration Scale (PAS) was used to substantiate the severity of aspiration if present. The test demonstrated both high sensitivity (91%; 95% confidence interval = 70.8-98.9) and diagnostic accuracy (96%; 95% confidence interval = 87.0-99.5) for detecting aspiration in individuals with tracheostomy. The Manipal Bedside Swallowing Screening Test is an easy to administer tool that has sufficient sensitivity to detect aspiration in individuals with tracheostomy. The MBSST will be an easy to administer tool and will help in screening for aspiration at bedside without any instrumental examination.

A smartphone-assisted test paper fluorescence sensing platform for visual detection of α-Ketoglutaric acid based on Metal-Organic frameworks

Developing an accurate, sensitive and visual strategy for quickly identifying biomarkers α-ketoglutaric acid (α-KA) is crucial for early disease diagnosis s Herein, we introduce a new fluorescence material, Eu3+@COMOC-4, synthesized by post-synthesis modification of a lanthanide-functionalized metal–organic frameworks (MOFs). This material serves as a visual fluorescence sensor to detect α-KA, with a distinct fluorescence response. Particularly, the sensor exhibits many advantages, such as good selectivity, high sensitivity and quick response. The quenching mechanism between the sensor and α-KA was also illustrated in detail. More significantly, a smartphone-integrated test paper fluorescence sensing platform was further developed for α-KA detection, which enables sensitive, real-time, and visual detection of α-KA. This work provides a sensitive and real-time biomarker detection strategy, which is expected to expand the application of MOFs in significant fields.

Core-shell MIL-53(Al)–NH2@UiO-66 coated solid-phase microextraction Arrow for the selective enrichment of nine alkylphenols in milk

Metal-organic frameworks (MOFs) hold significant potential for sample preparation, but single-MOF materials often face limitations in selectivity and extraction efficiency. To overcome these, a mesoporous MIL-53(Al)–NH2@UiO-66 composites with a core–shell structure was synthesized using an epitaxial growth strategy. This composite leverages the complementary properties of both MOFs, offering enhanced active sites and interaction forces for analytes. The structure and integration of the composite were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction, confirming their successful integration. To address the challenge of detecting alkylphenols (APs) in food matrices, known for their endocrine-disrupting properties and low concentrations, a new solid-phase microextraction (SPME) Arrow was fabricated using the MIL-53(Al)–NH2@UiO-66 composite combined with polyacrylonitrile as a binder. APs were detected using ultra-performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-ToF/MS). The developed SPME Arrow-UPLC-ESI-Q-ToF/MS method exhibits good linearity (R2 ≥ 0.9958), wide linear range (0.01–1000 μg L–1), and high sensitivity (limits of detection ranging from 0.005 to 0.01 μg L–1) for APs determination. This method was validated for determining nine APs in milk samples from various packing materials, with spiked recoveries ranging from 85.2 % to 115 % and relative standard deviations from 3.4 % to 13.6 %. This study demonstrates the potential of MOF-on-MOF composites in enhancing the performance of adsorbents for SPME pretreatment, offering a promising approach for improving analytical methodologies in food safety.

Construction of fluorescent probe based on phenoxazine for the detection of N2H4 in environmental, biological and food samples

Hydrazine (N2H4) is widely used in agrochemicals and pharmaceuticals, but unintentional releases of hydrazine can be transmitted through food, organisms and the environment, ultimately posing a serious hazard to human health. Consequently, the development of a rapid and sensitive analytical tool for the detection of N2H4 is necessary. In this study, we present the synthesis and application of a novel molecular probe (Probe PM). The probe is characterised by its simple synthesis, high yield and a range of analytical properties including very high sensitivity (limit of detection as low as 17.1 nM) and a pronounced fluorescence spectral blue shift of 146 nm. These attributes have enabled the successful implementation of Probe PM in the qualitative and quantitative detection and visualization of hydrazine in diverse environmental and biological matrices, including water samples, soil samples, food products, and biological systems. The probe has great potential for detecting environmental and food safety.

Bioplastic films from starch of Colocasia esculenta and its waste: A smart template for sensing applications

The over usage plastics have possessed serious threat to the ecological system. Thus progressive advancement in fabricating biodegradable and renewable bioplastics is persuasively required to furnish an effective alternative to non-biodegradable plastics. In this view, the current work highlights the production of starch based bioplastic films using waste Colocasia esculenta (taro herb) as a viable starting precursor. The functional ability of developed taro starch based film was further modified by incorporating carbon dots (CQDs) fillers generated from the waste slurry produced during starch extraction from taro herbs. The optimization of films production was achieved by varying the CQDs amount (0.4 %, 0.8 %, 2 % and 4 % w/w) on taro-based films using casting technology. The data illustrates that the addition of CQDs has the ability to enhance the fluorescence property, mechanical properties (Tensile Strength 0.332–4.635 MPa, Elongation at break 42.45–547.63 %) and water resistance ability of films (Moisture content 15–6.4 %, Water Solubility 50–30 % Water Vapour Transmission Rate 2.0012–1.0054 g−2 h−1 and Water Contact Angle 40.6–89.6°). The developed films are found to be thermally stable. The formed films possessed anti-oxidative abilities which safeguard the film from oxidative attacks and ultimately protect the film from the external environment. The fluorescence nanosensor probe has further been developed by utilizing CQDs embedded in a starch-based bioplastic nanocomposite. The developed sensor displayed selective sensing ability towards Fe2+ ion with high sensitivity and accuracy in aqueous medium. Thus, the proposed sensor in this work offers a portable, efficient, low-cost, disposable, non-lethal, and eco-friendly nanosensor for on-site monitoring of metal ion for the food, beverage, and pharmaceutical industries. This is one of the primary reports where metal ions sensing is reported for Taro@CQDs nanocomposites based films. Our outcomes of this work hold significant relevance to providing a smart sensory and biodegradable probe for metal ion sensing by using waste resources, thus offering a better and sustainable alternative for environmental remediation applications.

A novel electrochemical sensor based on aspartic acid polymer and carbonized-ZIF-67 for rapid sensing of arbutin

A novel electrochemical sensor modified by aspartic acid polymer and carbonized-ZIF-67 was prepared for arbutin detection. ZIF-67 was synthesized and carbonized, and then used as the substrate supporting of electrochemical sensor. Carbonized-ZIF-67 had a large specific surface and good electrical conductivity, which provided large electroactive area and promoted the electron transfer at the sensing interface. Aspartic acid polymer was prepared by cyclic voltammetry. Aspartic acid polymer could effectively absorb arbutin, resulting in the preconcentration of arbutin on sensor surface. Benefiting from the synergistic effect between carbonized-ZIF-67 and aspartic acid polymer, the prepared electrochemical sensor exhibited sensitive electrochemical response for arbutin. Under the optimum conditions, the electrochemical sensor achieved a wide linear range in the range from 5 to 110 μmol/L and a low detection limit of 0.41 μmol/L for arbutin. In practical application, the electrochemical sensor was employed to detect arbutin in green tea and whitening cream samples, exhibiting satisfactory recovery rates. With the outstanding features of easy operation, rapid response and high sensitivity, the prepared electrochemical sensor provided a convenient and effective tool for arbutin detection.

A novel highly sensitive test reaction for micromixing: Acid‐base neutralization and alkaline hydrolysis of ethyl oxalate

AbstractMicromixing in chemical reactors can be characterized through test reactions that are sensitive to mixing. A new pair of parallel competitive reactions, including acid–base neutralization and diethyl oxalate hydrolysis, is proposed in this work. It has clear principles and high sensitivity to micromixing with quantitative accuracy and operational simplicity. The measurement results obtained from stopped‐flow spectra show that the alkaline hydrolysis of diethyl oxalate follows second‐order kinetics, and the rate constant conforms to the Arrhenius equation k2 = 2.331 × 108 exp(−26.92 × 103/RT) (L/mol/s). The estimated half‐life of hydrolysis is approximately 3 × 10−4 s under the selected concentration combinations, which provides significant advantages for the micromixing assessment in the strong turbulent fluid environment. In the same stirred tank, the critical feed time of new test reaction is shorter than that of the Villermaux–Dushman reaction. Overall, this work provides practical ideas for screening other desired esters for fast hydrolysis to construct more test reactions for micromixing.