-
Journal of Visualized Experiments : JoVE Jul 2022Ex vivo preparations enable the study of many neurophysiological processes in isolation from the rest of the body while preserving local tissue structure. This work...
Ex vivo preparations enable the study of many neurophysiological processes in isolation from the rest of the body while preserving local tissue structure. This work describes the preparation of rat sciatic nerves for ex vivo neurophysiology, including buffer preparation, animal procedures, equipment setup and neurophysiological recording. This work provides an overview of the different types of experiments possible with this method. The outlined method aims to provide 6 h of stimulation and recording on extracted peripheral nerve tissue in tightly controlled conditions for optimal consistency in results. Results obtained using this method are A-fibre compound action potentials (CAP) with peak-to-peak amplitudes in the millivolt range over the entire duration of the experiment. CAP amplitudes and shapes are consistent and reliable, making them useful to test and compare new electrodes to existing models, or the effects of interventions on the tissue, such as the use of chemicals, surgical alterations, or neuromodulatory stimulation techniques. Both conventional commercially available cuff electrodes with platinum-iridium contacts and custom-made conductive elastomer electrodes were tested and gave similar results in terms of nerve stimulus strength-duration response.
Topics: Action Potentials; Animals; Electric Conductivity; Electric Stimulation; Electrodes; Neurophysiology; Rats; Sciatic Nerve
PubMed: 35913135
DOI: 10.3791/63838 -
Sensors (Basel, Switzerland) Jul 2022In this study, different eddy-current based probe designs (absolute and commercial reflection) are used to detect artificial defects with different sizes and at...
In this study, different eddy-current based probe designs (absolute and commercial reflection) are used to detect artificial defects with different sizes and at different depths in parts composed of stainless-steel (316) and titanium (TI-64) made by Laser Additive Manufacturing (LAM). The measured defect signal value using the probes is in the range of (20-200) millivolts. Both probes can detect subsurface defects on stainless-steel samples with average surface roughness of 11.6 µm and titanium samples with average surface roughness of 8.7 µm. It is found the signal reading can be improved by adding a coating layer made of thin paper to the bottom of the probes. The layer will decrease the surface roughness effect and smooth out the detected defect signal from any ripples. The smallest subsurface artificial defect size detected by both probes is an artificially made notch with 0.07 mm width and 25 mm length. In addition, both probes detected subsurface artificial blind holes in the range of 0.17 mm-0.3 mm radius. Results show that the absolute probe is more suitable to detect cracks and incomplete fusion holes, whereas the reflection probe is more suitable to detect small diameter blind holes. The setup can be used for defect detection during the additive manufacturing process once the melt pool is solidified.
PubMed: 35891120
DOI: 10.3390/s22145440 -
Methods in Molecular Biology (Clifton,... 2022The mitochondrial membrane potential (ΔψM) is the major component of the bioenergetic driving force responsible for most cellular ATP produced, and it controls a host...
The mitochondrial membrane potential (ΔψM) is the major component of the bioenergetic driving force responsible for most cellular ATP produced, and it controls a host of biological processes. In intact cells, assay readouts with commonly used fluorescence ΔψM probes are distorted by factors other than ΔψM. Here, we describe a protocol to calculate both ΔψM and plasma membrane potential (ΔψP) in absolute millivolts in intact single cells, or in populations of adherent, cultured cells. Our approach generates unbiased data that allows comparison of ΔψM between cell types with different geometry and ΔψP, and to follow ΔψM in time when ΔψP fluctuates. The experimental paradigm results in fluorescence microscopy time courses using a pair of cationic and anionic probes with internal calibration points that are subsequently computationally converted to millivolts on an absolute scale. The assay is compatible with wide field, confocal or two-photon microscopy. The method given here is optimized for a multiplexed, partial 96-well microplate format to record ΔψP and ΔψM responses for three consecutive treatment additions.
Topics: Cells, Cultured; Fluorescent Dyes; Membrane Potential, Mitochondrial; Microscopy, Fluorescence; Mitochondria
PubMed: 35771433
DOI: 10.1007/978-1-0716-2309-1_2 -
Journal of Glaucoma Aug 2022Twenty-four-hour IOP measurements with a CLS showed that among IOP indicators studied, the range of IOP fluctuation was most important and significantly larger in NTG...
PRCIS
Twenty-four-hour IOP measurements with a CLS showed that among IOP indicators studied, the range of IOP fluctuation was most important and significantly larger in NTG eyes compared with nonglaucoma eyes.
PURPOSE
We conducted the present study to determine (1) the best factor for distinguishing normal tension glaucoma (NTG) and nonglaucoma subjects based on the intraocular pressure (IOP) values measured by a CLS and (2) the optimal cutoff values of that factor.
SUBJECTS AND METHODS
The eyes of 18 nonglaucoma subjects and 26 NTG patients were examined. We evaluated 5 indicators: maximum IOP value, SD, IOP fluctuation range, the cosine-fit curve amplitude, and the amplitude of dual-harmonic regression values. We determined the indicators' cutoff values to distinguish between nonglaucoma subjects and NTG patients with the area under the curve.
RESULTS
The mean IOP values were 12.3±2.7 mm Hg in the nonglaucoma eyes and 12.5±3.1 mm Hg in the NTG eyes ( P =0.824). All 5 indicators were significantly higher in the NTG group. The best factor to distinguish the nonglaucoma subjects and NTG patients was the IOP fluctuation range ( P <0.0001, area under the curve=0.844); the cutoff level value was 436.5 millivolt equivalents.
CONCLUSIONS
Twenty-four-hour IOP measurements with a CLS showed that among IOP indicators studied, the range of IOP fluctuation was most important and significantly larger in NTG eyes compared with nonglaucoma eyes.
Topics: Circadian Rhythm; Contact Lenses; Glaucoma, Open-Angle; Humans; Intraocular Pressure; Low Tension Glaucoma; Tonometry, Ocular
PubMed: 35766388
DOI: 10.1097/IJG.0000000000002071 -
Physica Medica : PM : An International... Aug 2022The roles and responsibilities of medical physicists (MPs) are growing together with the evolving science and technology. The complexity of today's clinical trials...
INTRODUCTION
The roles and responsibilities of medical physicists (MPs) are growing together with the evolving science and technology. The complexity of today's clinical trials requires the skills and knowledge of MPs for their safe and efficient implementation. However, it is unclear to what extent the skillsets offered by MPs are being exploited in clinical trials across Europe.
METHODS
The EFOMP Working Group on the role of Medical Physics Experts in Clinical Trials has designed a survey that targeted all 36 current National Member Organisations, receiving a response from 31 countries. The survey included both quantitative and qualitative queries regarding the involvement of MPs in trial design, setup, and coordination, either as trial team members or principal investigators.
RESULTS
The extent of MPs involvement in clinical trials greatly varies across European countries. The results showed disparities between the roles played by MPs in trial design, conduct or data processing. Similarly, differences among the 31 European countries that responded to the survey were found regarding the existence of national bodies responsible for trials or the available training offered to MPs. The role of principal investigator or co-investigator was reported by 12 countries (39%), a sign of efficient collaboration with medical doctors in designing and implementing clinical studies.
CONCLUSION
Organisation of specific training courses and guideline development for clinical trial design and conduct would encourage the involvement of a larger number of MPs in all stages of trials across Europe, leading to a better standardisation of clinical practice.
Topics: Clinical Trials as Topic; Europe; Humans; Physician's Role; Surveys and Questionnaires
PubMed: 35717777
DOI: 10.1016/j.ejmp.2022.06.008 -
Journal of Bodywork and Movement... Jul 2022In the field of rehabilitation, the acute application of neuromuscular electrical stimulation (NMES) causes not only peripheral muscle contraction but also involve the...
BACKGROUND
In the field of rehabilitation, the acute application of neuromuscular electrical stimulation (NMES) causes not only peripheral muscle contraction but also involve the central nervous system by the transient increase in spinal motor neuron and cortical activity. Therefore it has been used in several fields of rehabilitation. Previous studies used surface electromyography to assess this effect. But we conducted our study to assess the effect of NMES on contralateral quadriceps muscle in normal individuals using another method needle electromyography.
METHODS
A study carried out on 20 normal males, who were subjected to (i) NMES Training Program for 60 min for the right quadriceps muscle. (ii) Assessment of EMG activity for rectus femoris muscle (RF) on the contralateral side. An assessment was done for minimal volition and maximal volition or interference pattern analysis, this assessment was done twice: before the start of NMES and during the session.
RESULTS
EMG of voluntary activity (Minimal volition) and Maximum voluntary activity analysis for RF muscles showed increased duration (in millisecond), amplitude (in millivolt) (P < 0.01), increased activity in turn per second, amplitude/turn (M) (uV) compared to the result before NMES application.
CONCLUSION
Our study provides a new evident date that the acute NMES application to the contralateral quadriceps muscles, leads to significant facilitation of the maximal voluntary power in the ipsilateral muscles through activation of efferent neural control. This facilitating effect of motor neurons in the contralateral muscles is likely due to the complex combination interaction between spinal and supraspinal control.
TRIAL REGISTRATION
Trial registration: PACTR202010887172053.
Topics: Electric Stimulation; Electromyography; Humans; Male; Muscle Contraction; Muscle, Skeletal; Quadriceps Muscle
PubMed: 35710227
DOI: 10.1016/j.jbmt.2022.03.005 -
Nature May 2022The scaling of silicon metal-oxide-semiconductor field-effect transistors has followed Moore's law for decades, but the physical thinning of silicon at sub-ten-nanometre...
The scaling of silicon metal-oxide-semiconductor field-effect transistors has followed Moore's law for decades, but the physical thinning of silicon at sub-ten-nanometre technology nodes introduces issues such as leakage currents. Two-dimensional (2D) layered semiconductors, with an atomic thickness that allows superior gate-field penetration, are of interest as channel materials for future transistors. However, the integration of high-dielectric-constant (κ) materials with 2D materials, while scaling their capacitance equivalent thickness (CET), has proved challenging. Here we explore transferrable ultrahigh-κ single-crystalline perovskite strontium-titanium-oxide membranes as a gate dielectric for 2D field-effect transistors. Our perovskite membranes exhibit a desirable sub-one-nanometre CET with a low leakage current (less than 10 amperes per square centimetre at 2.5 megavolts per centimetre). We find that the van der Waals gap between strontium-titanium-oxide dielectrics and 2D semiconductors mitigates the unfavourable fringing-induced barrier-lowering effect resulting from the use of ultrahigh-κ dielectrics. Typical short-channel transistors made of scalable molybdenum-disulfide films by chemical vapour deposition and strontium-titanium-oxide dielectrics exhibit steep subthreshold swings down to about 70 millivolts per decade and on/off current ratios up to 10, which matches the low-power specifications suggested by the latest International Roadmap for Devices and Systems.
PubMed: 35546188
DOI: 10.1038/s41586-022-04588-2 -
RSC Advances Apr 2021Lithium plating/stripping was investigated under constant current mode using a copper powder electrode in a super-concentrated electrolyte of lithium...
Lithium plating/stripping was investigated under constant current mode using a copper powder electrode in a super-concentrated electrolyte of lithium bis(fluorosulfonyl)amide (LiFSA) with methylphenylamino-di(trifluoroethyl) phosphate (PNMePh) and vinylene carbonate (VC) as additives. Typical Li plating/stripping for Cu electrodes in organic electrolytes of conventional lithium batteries proceeds at potentials of several millivolts a Li counter electrode. In contrast, a large overpotential of hundreds of millivolts was observed for Li plating/stripping with the super-concentrated electrolyte. When Li stripping started immediately after Li plating and with no rest time between plating and stripping, two potential plateaus, , two-step Li stripping, was observed. The potential plateau for the 1 stripping step appeared at -0.2 V a Li metal counter electrode. The electrical capacity for the 1 stripping step was 0.04 mA h cm, which indicates irregular Li stripping. Two-step Li stripping was also recorded using cyclic voltammetry. The electrochemical impedance spectroscopy (EIS) studies indicated that the two-step Li stripping behaviour reflected two different solid electrolyte interphases (SEIs) on electrodeposited Li in a Cu electrode. The SEI for the 1-step stripping was in a transition period of the SEI formation. The open circuit voltage (OCV) relaxation with an order of tens of hours was detected after Li plating and before Li stripping. The EIS study suggested a decrease of the charge transfer resistance in the Cu powder electrode during the OCV relaxation. Since the capacitance for the voltage relaxation was a dozen microfarads, it had a slight contribution to the 1-step Li stripping behaviour. The voltage relaxation indicated the possibility that it is difficult for Li ions to be electrodeposited or that the Li plating is in a quasi-stable state.
PubMed: 35423877
DOI: 10.1039/d1ra01490k -
Small Methods May 2022The traditional way to stabilize α-phase formamidinium lead triiodide (FAPbI ) perovskite often involves considerable additions of methylammonium (MA) and bromide into...
The traditional way to stabilize α-phase formamidinium lead triiodide (FAPbI ) perovskite often involves considerable additions of methylammonium (MA) and bromide into the perovskite lattice, leading to an enlarged bandgap and reduced thermal stability. This work shows a seed-assisted growth strategy to induce a bottom-up crystallization of MA-free perovskite, by introducing a small amount of α-CsPbBr /DMSO (5%) as seeds into the pristine FAPbI system. During the initial crystalization period, the typical hexagonal α-FAPbI crystals (containing α-CsPbBr seeds) are directly formed even at ambient temperature, as observed by laser scanning confocal microscopy. It indicates that these seeds can promote the formation and stabilization of α-FAPbI below the thermodynamic phase-transition temperature. After annealing not beyond 100 °C, CsPbBr seeds homogeneously diffused into the entire perovskite layer via an ions exchange process. This work demonstrates an efficiency of 22% with hysteresis-free inverted perovskite solar cells (PSCs), one of the highest performances for MA-free inverted PSCs. Despite absented passivation processes, open-circuit voltage is improved by 100 millivolts compared to the control devices with the same stoichiometry, and long-term operational stability retained 92% under continuous full sun illumination. Going MA-free and low-temperature processes are a new insight for compatibility with tandems or flexible PSCs.
PubMed: 35266331
DOI: 10.1002/smtd.202200048 -
Advanced Science (Weinheim,... May 2022Although adipose-derived mesenchymal stem cells (ADMSCs) isolated from patients' fat are considered as the most important autologous stem cells for tissue repair,...
Although adipose-derived mesenchymal stem cells (ADMSCs) isolated from patients' fat are considered as the most important autologous stem cells for tissue repair, significant difficulties in the neural differentiation of ADMSCs still impede stem cell therapy for neurodegenerative diseases. Herein, a wireless-electrical stimulation method is proposed to direct the neural differentiation of ADMSCs based on the electromagnetic effect using a graphene film as a conductive scaffold. By placing a rotating magnet on the top of a culture system without any inducer, the ADMSCs cultured on graphene differentiate into functional neurons within 15 days. As a conductive biodegradable nanomaterial, graphene film acts as a wireless electrical signal generator driven by the electromagnetic induction, and millivolt-level voltage generated in situ provokes ADMSCs to differentiate into neurons, proved by morphological variation, extremely high levels of neuron-specific genes, and proteins. Most importantly, Ca intracellular influx is observed in these ADMSC-derived neurons once exposure to neurotransmitters, indicating that these cells are functional neurons. This research enhances stem cell therapy for neurodegenerative diseases using autologous ADMSCs and overcomes the lack of neural stem cells. This nanostructure-mediated physical-signal simulation method is inexpensive, safe, and localized, and has a significant impact on neural regeneration.
Topics: Adipose Tissue; Cell Differentiation; Electromagnetic Phenomena; Graphite; Humans; Mesenchymal Stem Cells; Neural Stem Cells
PubMed: 35152569
DOI: 10.1002/advs.202104424