Current-clamp Research Articles

A novel fluorescent probe for rapid detection of sulfatase in vitro and in living cells

Sulfatase participates in a variety of physiological processes in organisms including hormone regulation, cell signaling, and bacterial pathogenesis. Current sulfatase fluorescent probes can be used to track sulfate esterase overexpression in cancer cells for diagnostic purposes and to understand the pathological activity of sulfate esterase. However, some sulfatase fluorescent probes based on the hydrolysis of the sulfate bond were easily disturbed by the catalytic activity of sulfatase. Herein, we developed the fluorescent probe BQM-NH2 for sulfatase detection, which was based on the quinoline-malononitrile. The probe BQM-NH2 showed a fast response to sulfatase within 1 min and satisfactory sensitivity with a calculated LOD of 1.73 U/L. Importantly, it was successfully used to monitor endogenous sulfate in tumor cells, indicating BQM-NH2 has the potential to monitor sulfatase under physiological and pathological conditions.

Investigation of rolling contact fatigue cracks using the transmitter-receiver eddy current testing under moving conditions

ABSTRACT Rolling contact fatigue (RCF) cracks online detection using eddy current testing (ECT) is in urgent demand. However, RCF cracks detection and evaluation in this way under moving conditions remains challenging due to the velocity effect in ECT. This paper aims to study the response of a transmitter-receiver eddy current probe to cracks under moving conditions and evaluate the depth and inclination angle of RCF cracks. In this paper, a high-speed eddy current testing system is developed to experimentally investigate the influence of coil gap, detection speed, and the lift-off on the eddy current probe’s response under moving conditions. In addition, the temporal and amplitude features of the eddy current signal are extracted to characterise the depth and inclination angle of the RCF cracks. The experimental results indicate the eddy current probe’s response can be improved by increasing the coil gap (coil centre distance) suitably, which can be done to compensate for the attenuation of the eddy current signal caused by detection speed and lift-off. The probe’s response hardly changes with an increase in detection speed when the driver and pick-up coils of the eddy current probe completely overlap. The crack depth and inclination angle can be evaluated under moving conditions.

Rational Design of pH-Independent and High-Fidelity Near-Infrared Tunable Fluorescent Probes for Tracking Leucine Aminopeptidase In Vivo.

Accurate detection of target analytes and generation of high-fidelity fluorescence signals are particularly critical in life sciences and clinical diagnostics. However, the majority of current NIR-I fluorescent probes are vulnerable to pH effects resulting in signal distortion. In this work, a series of fluorescence-tunable and pH-independent probes are reported by combining optically tunable groups of unsymmetric Si-rhodamines and introducing the methoxy instead of the spiro ring on the benzene ring at position 9. To validate the concept, the leucine aminopeptidase response site was introduced into Si-2,6OMe-NH2 with the best optical properties to synthesize Si-LAP for monitoring the intrahepatic LAP in vivo. Therefore, the design approach may provide a new and practical strategy for designing innovative functional fluorescent probes and generating high-stability and high-fidelity fluorescent signals.

Wintertime patterns of residential electricity use and indoor temperature in the composite climate of India

Wintertime electricity use in India has received little attention due to the growth of residential air conditioning (AC) in the summer and monsoon seasons. This paper combines monitoring (time-series) and survey (contextual) data to examine the wintertime pattern of daily electricity current, indoor temperature, and relative humidity profiles across a sample of 64 dwellings in the city of Hyderabad representing the composite climate of India. Monitoring data were recorded for 31 days (December 2021 with a mean daily outdoor temperature of 25°C) using a CT clamp meter and Bluetooth enabled sensors. Contextual data covered dwelling and household characteristics, and use of appliances. The winter peak period of electricity use was found to occur from 6:30-10:30 in the morning, likely to be for hot water (geysers) and cooking. This is different to the late evening/night-time peak observed in the summer due to use of air conditioning (AC). Only one dwelling showed potential signs of using space heating. Higher electricity use aligned with lower peak temperatures in some homes particularly in the high-income group, indicating the potential use of AC during winter. The wintertime morning electricity peak in India could be managed using thermal stores in geysers through pre-heating which could also offer demand response opportunities.

Detection of Cysteine Sulfenic Acid on E. coli Proteins with a Biotin-Benzoboroxole Probe.

S-sulfenylation of cysteine residues on proteins can effectively change protein structures and accordingly regulate their functions in vivo. Investigation of S-sulfenylation in different biological environments is thus vital for a systematic understanding of cellular redox regulation. In this work, a functional probe, biotin-benzoboroxole (Bio-ben), was designed for the detection of cysteine sulfenic acid (Cys-SOH). The performance of Bio-ben was characterized by small-molecule sulfenic acid, protein models, and proteome tests via mass spectra and western blotting. The results showed that Bio-ben was validated for cysteine sulfenic acid on proteins with good capture efficiency even at low concentrations. Compared with commonly used probes such as dimedone, the current probe has significantly shortened labeling time and exhibited comparable sensitivity. The proposed method provides a new approach for exploring S-sulfenylation in the oxidative modification of proteins and is helpful for related biological and clinical applications.

A new J.E probe for measurement of spatial profiles of power absorption in RF produced plasma.

This paper reports an indigenously developed probe for the measurement of spatial profiles of the absorbed/generated RF power density Pabs (W/m3) in RF discharges. The technique utilizes a calibrated current (J) probe based on the Rogowski coil principle and an electric field (E) probe based on capacitive coupling, both integrated into a single probe called the J.E probe. Various aspects of the probe, such as its design, fabrication, calibration, and limitations, were resolved before it was used for obtaining axial profiles of RF power absorption/generation. Also presented are the first experimental results for the absorbed power density profiles at the fundamental (13.56MHz) and harmonic (27.12MHz) along the length of a capacitively coupled discharge. The axial scans between the powered and grounded electrode were taken at different argon gas pressures (10-800mTorr) at a fixed RF power of 10W. Detailed analysis of the results shows that even for systems with large electrode gaps, i.e., plasmas with long bulk plasma regions, practically all the fundamental power is absorbed in a narrow edge region near the powered electrode, irrespective of the pressure. Absorption is high near the RF electrode since the RF fields peak in this region. Another important conclusion is that stochastic absorption of the fundamental and harmonic generation proceeds fairly efficiently in the vicinity of the powered electrode even at high pressures. It may be mentioned that the probe technique introduced here is the first of its kind, and although there is considerable scope for miniaturization, it has, nonetheless, provided some key insights into the nature of RF power absorption in capacitive discharges.

Non-destructive Evaluation combining HTS-SQUID with Eddy Current Testing Probe for Hear Transfer Pipes

1．はじめに

HIGH SODIUM INTAKE - EFFECTS ON AFFERENT RENAL NERVE ACTIVITY

Objective: Previous work of ours suggests that the sensitivity of renal afferent neurons is decreased under pathological conditions. Here we tested the hypothesis that pathologically decreased sensitivity of renal afferent neurons due to high salt diet is normalized after renal denervation. Design and method: Six male Sprague Dawley (SD) rats were put on high salt diet (HS; 8% NaCl) for 10 days. In another group of 18 rats on high salt diet (HS) left kidneys were denervated (DNX) 7 days prior to examination. 17 rats on standard diet with and without DNX were used as controls. Dorsal root ganglion neurons with renal afferents were investigated in primary neuronal cell culture using current clamp mode to assess action potential generation during current injection. Neurons were characterized as tonic highly active (less than 5 action potentials, AP) and phasic less active neurons (more than 5 AP upon stimulation). Results: In renal neurons from rats on HS the relation of tonic to phasic neurons shifted towards less active phasic units (62% tonic neurons in control vs. 42% on HS, p < 0.05, z-test). Denervation (DNX) of the left kidney in rats on high salt diet (HS-DNX) led to a recovery of afferent renal DRG neurons remaining vital after denervation. They regained their electrophysiological property of mainly tonic firing (42% tonic neurons in HS vs. 71% HS-DNX, p < 0.05, z-test). Conclusions: In rats on high salt diet the proportion of highly active tonic neurons with renal afferents decreased at the expense of less active phasic neurons. This HS effect could be abolished by DNX. Hence the input of afferent renal pathways to the central nervous system was normalized form the first neuron onward to the brain.

EMPAGLIFLOZIN IMPROVES IMPAIRED SENSITIVITY OF AFFERENT NEURONS WITH RENAL AXONS

Objective: Afferent renal nerve pathways likely play a role in salt sensitive hypertension. We recently reported that high salt diet (HS) impairs these afferent renal pathways in rats. Now we tested the hypothesis that during HS a decrease in sensitivity of renal afferent neurons is prevented by the SGLT2 inhibitor empagiflozin. Design and method: Respective groups of rats were put on HS containing 8% NaCl or a normal diet. Two groups (HS, controls) received empagiflozin 20 mg/kg BW/day orally. Renal neurons were retrogradely labeled with DiI. In culture, labeled dorsal root ganglion neurons (DRG Th11-L2) with renal afferents were investigated electrophysiologically using current clamp mode to assess action potential generation during current injection. Neurons were characterized as tonic highly active ( less than 5 action potentials, AP) and phasic less active neurons (more than 5 AP upon stimulation). Results: In neurons from rats on HS, the relation of tonic highly active neurons to less active phasic neurons shifted consistently towards phasic units (63,8% tonic neurons in controls vs. 42%* on HS, *p < 0.05, z-test). However, continuous treatment with empagiflozin preserved the proportion of tonic neurons as in controls (67,9% on HS with concomitant administration of empagiflozin). In controls, empagiflozin did not affect the proportion of tonic to phasic neurons (63,8% tonic neurons in controls vs. 67,9% on HS & empagliflozin, p = 0.7, z-test). Blood pressure and heart rate were not altered by HS and/or treatment with any chosen dose of empagiflozin. Conclusions: In rats, chronically elevated sodium intake (8% NaCl) reduced the sensitivity and stimulability of renal afferent DRG neurons. Under these circumstances, concomitant treatment with the SGLT2 inhibitor empagiflozin preserved the function of renal afferent DRG neurons. SGLT 2 inhibitors may help to treat dysfunction of renal innervation in cardiovascular disease.

Photocaged activity-based probes for improved monitoring of protein S-sulfenylation in living cells

Protein S-sulfenylation (protein sulfenic acid), as one of the most significant oxidative post-translational modifications (OxiPTMs), plays a vital role in regulating protein function. A variety of activity-based probes have been developed to profile sulfenic acid in living cells. However, due to the transient presence and low content of sulfenic acid in living cell, high doses of probes are needed to achieve efficient labeling. More importantly, current probes have no temporal control over sulfenic acid labeling. To overcome these limitations, two caged cysteine sulfenic acid probes DYn-2-ONB and DYn-2-Cou with either an o-nitrobenzyl or coumarin protecting group were developed in this study. Both probes can be efficiently uncaged via irradiation to produce the active C-nucleophile probe DYn-2. Labeling assay in living cells demonstrated DYn-2-ONB exhibited better labeling capacity compared with DYn-2, providing it as a powerful tool for improved monitoring of protein S-sulfenylation in living cells.

A novel fluorescent probe for imaging endogenous hydrogen sulfide in living cells and mice models of acute liver injury

Hydrogen sulfide (H2S) performs essential functions in several physiological and pathological procedures, such as liver cirrhosis, diabetes mellitus, and cancer. To optimize the H2S detection in practical applications, herein, a new probe YG-H2S for the fluorescent imaging of H2S was developed. Compared with the current H2S probes, the main advantages of YG-H2S were a wide pH range (5.0–9.0), a relatively fast response (within 10 min), and high selectivity from the competitive species (including biological mercaptan). Owing to the low cytotoxicity of YG-H2S, it was good for the biological depth imaging in biological events. YG-H2S could detect endogenous H2S in HeLa cells. In addition, YG-H2S could monitor the level of H2S in 4 T1-xenograft and acute liver injury model mice as well as in separate tissues. Consequently, YG-H2S might be a potential method for detecting H2S in preliminary diagnosis.

Expression of hyperpolarization-activated current (Ih) in zonally defined vestibular calyx terminals of the crista.

Calyx terminals make afferent synapses with type I hair cells in vestibular epithelia and express diverse ionic conductances that influence action potential generation and discharge regularity in vestibular afferent neurons. Here we investigated the expression of hyperpolarization-activated current (Ih) in calyx terminals in central and peripheral zones of mature gerbil crista slices, using whole cell patch-clamp recordings. Slowly activating Ih was present in >80% calyces tested in both zones. Peak Ih and half-activation voltages were not significantly different; however, Ih activated with a faster time course in peripheral compared with central zone calyces. Calyx Ih in both zones was blocked by 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride (ZD7288; 100 µM), and the resting membrane potential became more hyperpolarized. In the presence of dibutyryl-cAMP (dB-cAMP), peak Ih was increased, activation kinetics became faster, and the voltage of half-activation was more depolarized compared with control calyces. In current clamp, calyces from both zones showed three different categories of firing: spontaneous firing, phasic firing where a single action potential was evoked after a hyperpolarizing pulse, or a single evoked action potential followed by membrane potential oscillations. In the absence of Ih, the latency to peak of the action potential increased; Ih produces a small depolarizing current that facilitates firing by driving the membrane potential closer to threshold. Immunostaining showed the expression of HCN2 subunits in calyx terminals. We conclude that Ih is found in calyx terminals across the crista and could influence conventional and novel forms of synaptic transmission at the type I hair cell-calyx synapse.NEW & NOTEWORTHY Calyx afferent terminals make synapses with vestibular hair cells and express diverse conductances that impact action potential firing in vestibular primary afferents. Conventional and nonconventional synaptic transmission modes are influenced by hyperpolarization-activated current (Ih), but regional differences were previously unexplored. We show that Ih is present in both central and peripheral calyces of the mammalian crista. Ih produces a small depolarizing resting current that facilitates firing by driving the membrane potential closer to threshold.

An Analysis on Chinese EFL Learners’ Understanding of “Direct Object/Subject” Garden Path Sentences

The current study probes into the comprehension of “DO/S” GP sentences by Chinese EFL learners with different language proficiencies. 70 questionnaires are obtained. The results show that 60% triggering condition is not reached in high language proficiency group and no GP ambiguity is found, whereas the GP ambiguity is found and eliminated by low-proficiency group. And the level of language proficiency influences the emergence of GD phenomenon (x2=12.570, p=.000<.05). The Q&A test reveals the residual of the initial misunderstanding among learners. Although the 60% triggering condition is not reached, we find that the comprehension ability differs significantly between the two groups based on the scores of their answers (p=.004<.05). It can be safely concluded that the L2 proficiency will affect learners’ comprehension of “DO/S” GP sentences. The higher L2 proficiency learners gain, the more likely they may eliminate the ambiguation of GP sentences and there will be less residual of misunderstanding.

Albicanol antagonizes PFF-induced mitochondrial damage and reduces inflammatory factors by regulating innate immunity

As an environmental pollutant, profenofos (PFF) can seriously endanger human health through the food chain. Albicanol is a sesquiterpene compound with antioxidant, anti-inflammatory, and anti-aging properties. Previous studies have shown that Albicanol can antagonize apoptosis and genotoxicity caused by PFF exposure. However, the toxicity mechanism of PFF regulating hepatocyte immune function, apoptosis, and programmed necrosis and the role of Albicanol in this process have not been reported yet. In this study, grass carp hepatocytes (L8824) were treated with PFF (200 μM) or combined with Albicanol (5 ×10−5 μg mL−1) for 24 h to establish an experimental model. The results of JC-1 probe staining and Fluo-3 AM probe staining showed increased free calcium ions and decreased mitochondrial membrane potential in L8824 cells after PFF exposure, suggesting that PFF exposure may lead to mitochondrial damage. Real-time quantitative PCR and Western blot results showed that PFF exposure could increase the transcription of innate immunity-related factors (C3, Pardaxin 1, Hepcidin, INF-γ, IL-8, and IL-1β) in L8824 cells. PFF up-regulated the TNF/NF-κB signaling pathway and the expression of caspase-3, caspase-9, Bax, MLKL, RIPK1, and RIPK3 and down-regulated the expression of Caspase-8 and Bcl-2. Albicanol can antagonize the above-mentioned effects caused by PFF exposure. In conclusion, Albicanol antagonized the mitochondrial damage, apoptosis, and necroptosis of grass carp hepatocytes caused by PFF exposure by inhibiting the TNF/NF-κB pathway in innate immunity.

A Quencher-Based Blood Autofluorescence-SuppressionStrategy Enables the Quantification of Trace Analyte in Whole Blood.

Precise quantification of trace components in whole blood via fluorescence is of great significance. However, the applicability of current fluorescent probes in whole blood is largely hindered by the strong blood autofluorescence. Here, we proposed a blood autofluorescence-suppressed sensing strategy to develop an activable fluorescent probe for quantification of trace analyte in whole blood.Based on inner filter effect, by screening fluorophores whose absorption overlapped with the emission of blood, a redshift BODIPYquencher with an absorption wavelength ranging from 600-700 nm was selected for its superior quenching efficiencyand high brightness. Two 7-nitrobenzo[c] [1,2,5] oxadiazole ether groups were introduced onto the BODIPY skeleton for quenching its fluorescence and the response of H2S, a gas signal molecule that can hardly be quantified because of its low concentration in whole blood. Such detection system shows a pretty low background signal and high signal-to-back ratio, the probe thus achieved the accurate quantification of endogenous H2S in 20-fold dilution of whole blood samples, which is the first attempt of quantifying endogenous H2S in whole blood. Moreover, this autofluorescence-suppressed sensing strategy could be expanded to other trace analytes detection in whole blood, which may accelerate the application of fluorescent probes in clinical blood test.

A Quencher‐Based Blood‐Autofluorescence‐Suppression Strategy Enables the Quantification of Trace Analytes in Whole Blood

AbstractPrecise quantification of trace components in whole blood via fluorescence is of great significance. However, the applicability of current fluorescent probes in whole blood is largely hindered by the strong blood autofluorescence. Here, we proposed a blood autofluorescence‐suppressed sensing strategy to develop an activable fluorescent probe for quantification of trace analyte in whole blood. Based on inner filter effect, by screening fluorophores whose absorption overlapped with the emission of blood, a redshift BODIPY quencher with an absorption wavelength ranging from 600–700 nm was selected for its superior quenching efficiency and high brightness. Two 7‐nitrobenzo[c] [1,2,5] oxadiazole ether groups were introduced onto the BODIPY skeleton for quenching its fluorescence and the response of H2S, a gas signal molecule that can hardly be quantified because of its low concentration in whole blood. Such detection system shows a pretty low background signal and high signal‐to‐back ratio, the probe thus achieved the accurate quantification of endogenous H2S in 20‐fold dilution of whole blood samples, which is the first attempt of quantifying endogenous H2S in whole blood. Moreover, this autofluorescence‐suppressed sensing strategy could be expanded to other trace analytes detection in whole blood, which may accelerate the application of fluorescent probes in clinical blood test.

Near-Infrared Photodynamic Chemiluminescent Probes for Cancer Therapy and Metastasis Detection.

There is growing interest in the development of chemiluminescence (CL) probes for phototheranostics because of their minimized tissue autofluorescence. However, due to a lack of near-infrared (NIR)-absorbing chemiluminophores, current probes for NIR CL-guided phototherapy are based on nanoparticles made up of multiple components. We report bright unimolecular chemiluminophores with NIR absorptions and emissions, long CL half-lives and ideal photodynamic efficiency. One luminophore is modified into an activatable probe, DBPOL , with a turn-on CL signal and photodynamic activity that are specific to a cancer biomarker. The highly sensitive DBPOL allows CL-guided photodynamic therapy which completely inhibits tumor growth and lung metastasis in mouse models, and can be applied for noninvasive monitoring of lung metastasis. We provide molecular guidelines for NIR-absorbing CL probes for imaging-guided phototherapy.

Near‐Infrared Photodynamic Chemiluminescent Probes for Cancer Therapy and Metastasis Detection

AbstractThere is growing interest in the development of chemiluminescence (CL) probes for phototheranostics because of their minimized tissue autofluorescence. However, due to a lack of near‐infrared (NIR)‐absorbing chemiluminophores, current probes for NIR CL‐guided phototherapy are based on nanoparticles made up of multiple components. We report bright unimolecular chemiluminophores with NIR absorptions and emissions, long CL half‐lives and ideal photodynamic efficiency. One luminophore is modified into an activatable probe, DBPOL, with a turn‐on CL signal and photodynamic activity that are specific to a cancer biomarker. The highly sensitive DBPOL allows CL‐guided photodynamic therapy which completely inhibits tumor growth and lung metastasis in mouse models, and can be applied for noninvasive monitoring of lung metastasis. We provide molecular guidelines for NIR‐absorbing CL probes for imaging‐guided phototherapy.

Water-Cooled Fast-Response Wall-Static Pressure Probes for Harsh Combustor Environment Applications

The present paper discusses the design methodology for a water-cooled fast-response wall-static pressure probe intended for measurements in the combustion chamber of gas turbines, as well as the results from a series of tests performed with the prototype of the probe mounted in the primary zone of the combustion chamber of a turboshaft engine test rig. The first part of the present paper reviews the design methodology of a water-cooled fast-response wall static pressure probe intended for measurements of combustion noise and instabilities in gas turbine combustors, describing the optimization of measurement performance in terms of frequency bandwidth ([0 – 40kHz]) as well as the design of the cooling layout ensuring the sensor’s integrity within a harsh environment. The second part of the paper focuses on the analysis of the results obtained from trial tests performed using the probe prototype mounted in the primary zone of the combustion chamber of a helicopter engine test rig. The strengths and strong potential for further growth of the current probe design are highlighted, while its shortcomings and (short-term) solutions to these shortcomings are also discussed.

Electrical Control and Monitoring Home System With ACS712 Sensor & Relay Module via Blynk

Electrical load control and monitoring system is a device designed to control and monitor electricity consumption. The process of monitoring electric loads uses a power sensor model ACS712 which is connected to a relay module to supply electric loads and stop using electric loads if power consumption exceeds a predetermined capacity of 1000 watts so that energy control can be carried out. The microcontroller used is the NodeMCU esp8266 microcontroller which functions as the main control system that will be linked to the blynk application with the aim of being able to monitor it in real time in the future. By conducting an experiment assembling the ACS712 sensor module with NodeMCU esp8266 which produces a monitoring feature for reading current, power, energy and peak power measurements from the IoT blynk application through the ACS712 sensor. The results of this study are a control and monitoring of household electricity measurements through the blynk application to control the use of electrical energy loads from household electronic devices in the form of readings of current, power, energy, and stopping the supply of electric power to loads connected to the ACS712 sensor and relay. module. The Blynk IoT application, the ACS712 sensor is almost close to the measuring instrument or clamp meter used so that it is able to properly and correctly monitor electricity usage in household loads