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Introduction to Noninvasive Therapies
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
Mechanisms of TENS therapy include two primary, neural, pain relief mechanisms which can be excited by TENS stimulation: (1) Activity on the Aβ sensory (nonnociceptive) nerve fibers activates the pain gate control mechanism; that is, it reduces the transmission of a pain signal on the “C” nerve fibers, through the spinal cord, thence to the brain. Aβ fibers are best stimulated at a high rate (90–130 pps). (2) An alternate approach is to use an LF stimulation (2–5 pps) to stimulate the fast Aδ pain fibers which activate opioid pathways in the CNS. These provide pain relief by causing the release of endogenous opioids (enkephalins) in the spinal cord and CNS which reduces the activation of the noxious sensory pathways. Alternately, burst-mode TENS stimulation can be used: A train of 100 pps current pulses is periodically interrupted with a train of LF (5 pps) pulses, ensuring both Aβ and Aδ afferent fibers are stimulated (Physiopedia 2015b).
Longitudinal metabolic alterations in plasma of rats exposed to low doses of high linear energy transfer radiation
Published in Journal of Environmental Science and Health, Part C, 2021
Tixieanna Dissmore, Andrew G DeMarco, Meth Jayatilake, Michael Girgis, Shivani Bansal, Yaoxiang Li, Khyati Mehta, Vijayalakshmi Sridharan, Kirandeep Gill, Sunil Bansal, John B Tyburski, Amrita K Cheema
The column eluent was introduced into the Xevo G2-S mass spectrometer by electrospray operating in either negative or positive electrospray ionization mode. Positive mode had a capillary voltage of 3.00 kV and a sampling cone voltage of 30 V. Negative mode had a capillary voltage of 2.00 kV and had a sampling cone voltage of 30 V. The desolvation gas flow was set to 600 L/hour and the desolvation temperature was set to 500 °C. The cone gas flow was 25 L/hour and the source temperature was set to 100 °C. The data were acquired in the sensitivity MS mode with a scan time of 0.300 seconds and an interscan time of 0.014 seconds. Accurate mass was maintained by infusing Leucine Enkephalin (556.2771 [M + H]+/554.2615 [M-H]-) in 50% aqueous acetonitrile (1.0 ng/mL) at a rate of 10 µL/min via the Lockspray interface every 10 seconds. The data were acquired in centroid mode with a 50.0 to 1200.0 m/z mass range for TOF-MS scanning. An aliquot of each sample was pooled and used as a quality control (QC) which represented all metabolites present. This QC sample was run at the beginning of the sequence to condition the column and then injected every 10 samples to check mass accuracy, ensure presence of internal standard, and to monitor shifts in retention time and signal intensities.
Solvent Extraction Studies for the Separation of Trivalent Actinides from Lanthanides with a Triazole-functionalized 1,10-phenanthroline Extractant
Published in Solvent Extraction and Ion Exchange, 2020
Peter Zsabka, Tomas Opsomer, Karen Van Hecke, Wim Dehaen, Andreas Wilden, Giuseppe Modolo, Marc Verwerft, Koen Binnemans, Thomas Cardinaels
All chemicals used for the synthesis of EH-BTzPhen were purchased from Acros Organics, Sigma Aldrich, Alfa Aesar and TCI Europe and used as received. For column chromatography, 70–230 mesh silica 60 (Acros) was used as the stationary phase. NMR spectra were recorded on a Bruker Avance III HD 400 spectrometer and chemical shifts (δ) are reported in parts per million (ppm) referenced to tetramethylsilane (1H), or the internal (NMR) solvent signal (13C). The high-resolution mass spectrum was acquired on a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Synapt G2 HDMS, Waters, Milford, MA). The sample was infused at 3 µl/min and the spectrum was obtained in positive ionization mode with a resolution of 15000 (FWHM) using leucine enkephalin as lock mass. The melting point was determined on a Mettler-Toledo DSC 1 instrument, using a heating rate of 4 °C min−1 and under a helium atmosphere.
Drying kinetics and effect of air-drying temperature on chemical composition of Phyllanthus amarus and Phyllanthus niruri
Published in Drying Technology, 2018
Adriana Dutra Sousa, Paulo Riceli Vasconcelos Ribeiro, Kirley Marques Canuto, Guilherme Julião Zocolo, Rita de Cassia Alves Pereira, Fabiano André Narciso Fernandes, Edy Sousa de Brito
To identify potential discriminatory compounds of extracts obtained from Phyllanthus samples subjected to different drying temperatures, a multivariate analysis using UPLC–MS data was performed.[15] An Acquity UPLC system (Waters, Milford, MA, USA) coupled to a quadrupole/time-of-flight (QTOF) system (Waters, Milford, MA, USA) was used. The compounds were separated on an Acquity BEH C18 (1.7 µm, 2.1 × 150 mm2; Waters, Milford, MA, USA) column maintained at 40°C. The eluent was a mixture of A (0.1% formic acid in water) and B (0.1% formic acid in acetonitrile) at a flow rate of 0.4 mL/min. The gradient varied linearly from 2 to 95% B (v/v) from 0 to 15.0 min, was held constant at 100% B from 15.1 to 17.0 min, and concluded with a final wash and re-equilibration with 2% B from 17.1 to 19.1 min. The sample injection volume was 5 µL, and the spectrometer operated with a MSE centroid. Mass spectra were recorded in both positive and negative electrospray ionization (ESI) modes at a mass range between 110 and 1,180 Da, with a scan time of 0.1 s, and with leucine enkephalin as a lock mass standard. The samples were dissolved in water at a concentration of 2 mg/mL and filtered through 0.22 µm PTFE membranes.