Miniature Discharge Research Articles

Battery-Operated and Self-Heating Solid-Phase Microextraction Device for Field Detection and Long-Term Preservation of Mercury in Soil.

The application of headspace solid-phase microextraction (HS-SPME) for mercury preservation and detection still has several shortcomings, including the use of high-temperature desorption chamber, the consumption of expensive reagent (NaBEt4 or NaBPr4), and analyte loss during sample storage. Herein, a self-heating HS-SPME device using a gold-coated tungsten (Au@W) fiber was developed for the field detection of mercury in soil by miniature point discharge optical emission spectrometry (μPD-OES). Hg2+ was reduced to Hg0 with NaBH4 solution and then preconcentrated with the Au@W fiber. The adsorbed Hg0 could be rapidly desorbed by directly heating the fiber with a mini lithium battery and subsequently detected by μPD-OES. A limit of detection (LOD) of 0.008 mg kg-1 was obtained with a relative standard deviation (RSD) of 2.4%. The accuracy of the self-heating HS-SPME was evaluated by analyzing a soil certified reference material (CRM) and nine soil samples with satisfactory recoveries (86-111%). Compared to the conventional external heating method, the proposed method reduces desorption time and power consumption from 80 s and 60 W to 20 s and 2.5 W, respectively. Moreover, the self-heating device enables the μPD-OES system to remove the high-temperature desorption chamber, making it more compact and suitable for field analytical chemistry. Interestingly, the Au@W SPME fiber can be also used for the long-term preservation of mercury with a sample loss rate <5% after 30 days of storage at room temperature.

A high-throughput atomic emission analyzer for simultaneous field detection of dissolved inorganic and organic carbon in seawater and lake water

Dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) are two important indicators of global carbon cycle. However, there are no portable analyzers available to simultaneously accomplish high-throughput field detection of them in the same sample. Herein, a simple analyzer comprising a dual-mode reactor to accomplish both chemical vapor generation and headspace sampling, and a miniature point discharge optical emission spectrometer (μPD-OES) was developed for simultaneous and high-throughput detection of DIC and DOC in seawater and lake water. Phosphoric acid and persulfate were successively injected into sample solutions to convert DIC and DOC to CO2 under the conditions of magnetic stirring and UV irradiation, respectively. Subsequently, the generated CO2 was swept into the μPD-OES for quantitation of DIC and DOC via monitoring carbon atomic emission at 193.0 nm. Under optimal conditions, limits of detection for DIC and DOC (as C) were both 0.01 mg L−1 with relative standard deviations (n = 20) better than 5% and sample throughput of 80 samples per hour. Compared to conventional analyzers, the proposed instrument provides the advantages of high throughput, compactness, low energy consumption and eliminates expensive instruments. The accuracy of the system was validated by simultaneous determination of DIC and DOC in various water samples in laboratory and field environments.

Rapid and sensitive quantification of cyclamate in beverages by miniature microplasma optical emission spectrometry

Most of the available methods for the quantification of cyclamate depend on laboratory instruments and their application in the field was limited. Herein, a simple and sensitive method was developed for the determination of cyclamate in beverage samples based on chemical vapor generation and miniature point discharge optical emission spectrometry (μPD-OES). The combination of headspace sampling and μPD-OES not only simplifies the separation process of cyclamate, improves sensitivity, and alleviates matrix interference but also eliminates the use of a bulky and expensive instrument. Under the optimal conditions, this method provided a limit of detection of 0.1 mg L−1 comparable to or better than most reported methods. The method eventually was applied to 14 different beverages and cyclamate was found below the threshold set by Chinese Standards for Food Additives. The proposed method provides great potential for the field analysis of cyclamate in the supervision of food safety.

Miniature microplasma carbon optical emission spectrometry for detection of dissolved oxygen in water

As one of the most important quality parameters of natural water, the quantification of dissolved oxygen (DO) attracts considerable attention in environmental analytical chemistry. In this work, an accurate and novel strategy based on selective oxidation reaction and miniature point discharge optical emission spectrometry (μPD-OES) is proposed for the simple, fast, and efficient quantitative analysis of DO in natural water samples. The DO present in the tested sample can easily oxidize an equivalent amount of manganese ions (Mn2+) to an insoluble precipitate of manganese hydroxide (Mn(OH)3) under alkaline conditions. The precipitate is able to convert oxalate to carbon dioxide (CO2) in the presence of H2SO4. Consequently, the determination of DO is accomplished via the detection of CO2 by μPD-OES at 193.0 nm. Under the optimum conditions, a limit of detection for DO detection was 0.016 mg L−1. Besides, a good precision of 3.8% was obtained for the determination of DO. Finally, the DO in tap water, river water, and lake water samples was successfully analyzed and the obtained results are in good agreement with those obtained by a Chinese national standard method (GB 7489-87), thus demonstrating that the proposed method retains a remarkable potential for the on-site analysis of DO in environmental surface water samples.

RETRACTED: Hospital embedded system and acupuncture treatment of vascular cognitive impairment after stroke

Customary electronic needle therapy, the main pot can animate, and while deciding the patient, have their solidarity. Brilliant electronic needle therapy utilizes the biosensor and fluffy procedures to tackle these issues because of a remote electronic needle therapy framework utilizing the sensor module. Signal for treatment will be explored to the rules for the electronic needle treatment identifying pad plan. To change the needle therapy and power and time of a few patients' focus, build up a versatile remote needle therapy framework utilizing fluffy innovation. A productive remote electronic needle therapy treatment framework to acquire needle therapy rapidly utilizes the canny analytic framework. Stroke patients with intellectual debilitation after a stroke happens as often as possible. The danger of intellectual hindrance after stroke, age, and instructive foundation are identified with these two segment factors as occupation and veins. The component's fundamental psychological impedance after stroke isn't known in detail. A combination of white issue sores and miniature cerebral discharge, cerebellar vascular sickness or stroke of, alone or in the blend, add to the pathogenesis of psychological disability after stroke. After a stroke and benefit from the anti-dementia drug, cognitive impairment treatment can only not take measures to manage the cerebrovascular disease. Mechanism of the characteristics and cognitive impairment after a stroke and discussions promise these patients' management strategies. Internet of things, in the field of medical care. The continuous increase of IoT solutions for health care cannot be out of this model. Contribution introduces a direction for realizing the Internet of Things (IOT) and global connectivity between healthcare environments. All that is required to integrate into the worldwide environment are all significant challenges. In this revolution, health care collected from a minimum of sensors has been re-designed to see the big data.

Application of the view factor model on the particle-in-cell and Monte Carlo collision code.

Particle-in-cell and Monte Carlo collision (PIC-MCC) has been widely adopted as a simulation method for electric propulsion. However, neutral atoms move much more slowly than other species, which can cause a serious reduction in simulation speed. In this work, we investigate the view factor model in combination with the PIC-MCC method and propose a method for simulating three-dimensional neutral atoms. The accuracy of the PIC-MCC method can be significantly improved by updating the neutral distribution periodically. We compare the computational results with the fixed-neutral PIC-MCC model of the miniature ring-cusp discharge experiment at the University of California, Los Angeles (UCLA). The plasma distribution and potential distribution of the simulation match well with the UCLA experimental data. Compared with the fixed-neutral model, the view factor model increases the simulation time by only 33% while it improves the distribution accuracy of neutrals, plasma density, and electric potential, and reduces the simulation errors of discharge current and discharge power from 19.8% to 9.8%. The accuracy of PIC-MCC simulation has been improved at the expense of slightly increasing the computational time.

Growth of Carbonaceous Nanoparticles on Steel Fiber from Candle Flame for the Long-Term Preservation of Ultratrace Mercury by Solid-Phase Microextraction.

An extremely simple, cost-effective, and one-step method was developed for the preparation of solid-phase microextraction (SPME) fibers via the in situ synthesis of carbonaceous nanoparticles on the surface of stainless steel fiber from a candle flame. The prepared SPME fiber provided excellent adsorption capability toward Hg2+ derived with sodium tetraethylborate and was explored for the separation, preconcentration, and long-term preservation of ultratrace mercury in natural water samples. Moreover, the SPME fiber was further utilized for the highly sensitive routine analysis and field analysis of mercury with a commercial atomic fluorescence spectrometer (AFS) and a miniature point discharge optical emission spectrometer (μPD-OES), respectively. Under the optimum conditions, detection limits of 0.0005 μg L-1 and 0.007 μg L-1 together with relative standard deviations (RSDs) less than 5.8% were obtained for Hg2+ by headspace SPME-AFS and SPME-μPD-OES, respectively. The practicality of the prepared SPME fiber was validated via the determination of Hg2+ in real water samples with satisfactory recoveries (79-115%). Long-term preservation of mercury at parts per trillion level was undertaken at -20 °C and the sample loss rates were less than 5% after 9 days of storage, respectively, indicating that the storage performances of mercury provided by the proposed method are much better than that obtained by conventional methods. Notably, the extraction performance of the SPME fiber is not decreased obviously even after more than 100 times of operation. Due to its advantages of high sensitivity, high stability, simple operation, low cost, and low energy consumption, this method provides an avenue for the field analysis and long-term preservation of mercury in the field of environmental analytical chemistry.

Reduction of mercury(II) by electrons contained in carbon dots: An environmentally friendly cold vapor generation for mercury analysis

In this work, the reduction of mercury ions (Hg2+) to elemental mercury (Hg0) was easily achieved using highly reductive carbon dots (r-CDs), which synthesized from sucrose by a simple and cost-effective method. After a careful mechanistic study, the reduction was probably accomplished with the large numbers of electrons contained in r-CDs rather than the oxidation of its functional groups. Additionally, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that the r-CDs were nontoxic to wildlife and human beings. Consequently, the r-CDs were used as an alternative to toxic reductants (SnCl2 or NaBH4) for the sensitive and in situ determination of mercury by cold vapor generation (CVG) coupled to a miniature point discharge optical emission spectrometer (μPD-OES). Limit of detection of 0.05 μg/L was obtained for Hg2+, with relative standard deviation (RSD) less than 5.4% at a concentration of 5 μg/L. The accuracy of r-CDs induced CVG-μPD-OES was validated by the determination of mercury in a certified reference material (DOLT-5, dogfish liver) and five natural water samples collected from different rivers and lakes in Chengdu City. Since r-CDs are nontoxic and prepared from abundant and inexpensive sucrose, the r-CDs induced CVG-μPD-OES retains the great potential for the inexpensive and environmentally friendly field analysis of mercury in natural water. The accuracy of the proposed method was validated by the analysis of a certified reference material and several water samples with satisfactory results.

On pulsating DD neutron yield under inertial electrostatic confinement of complex plasma at miniature vacuum discharge

We continue to analyze the effects of deuteron oscillations in potential well of a virtual cathode under inertial electrostatic confinement based on nanosecond vacuum discharge. The goal of this paper is to present and discuss in detail available experimental results on pulsating DD neutron yield at this scheme. Also, the results of simulations for virtual cathodes and potential wells for particular experimental regimes of neutron yields are shown and discussed, as well as comparison with available similar scheme of periodical oscillating plasmas spheres for fusion.

INVESTIGATING THE ACT OF DESIGN IN DISCHARGE CONCEPT USING PMRI

The goal of this research is to investigate the act of design in discharge concept using Pendidikan Matematika Realistik Indonesia (PMRI) approach with Lapindo's Mud phenomenon as a context. Design research was chosen as method used in this research that consist of three phases, namely preparing for the experiment, teaching experiment, and retrospective analysis. Based on the result of investigating from findings and the data obtained in this research, it can be concluded that the use of instructional design using PMRI can support students' understanding in learning the concept of discharge. Observing activities Lapindo mud photos, watching videos Lapindo mud, observing miniature discharge of Lapindo mud, volume of water and time of data collection are needed, and finding discharge of Lapindo mud are conducted in this research.Keywords: discharge, design research, PMRI DOI: dx.doi.org/10.22342/jme.72.129

Plasma Structure of Miniature Ring-Cusp Ion Thruster Discharges

Previous miniature ion thruster studies have demonstrated impressive performance using ring-cusp discharges. These studies suggest that the magnetic field must be sufficiently strong to increase primary electron confinement times for ionization, but weak enough to allow plasma electrons to escape and maintain the plasma potential necessary for ionization. To investigate these phenomena, an experiment was developed to allow detailed measurements of the internal structure and characteristics of a miniature ring-cusp discharge. These measurements provide spatially resolved values for plasma density, electron temperature, and plasma potential along a meridian plane. The magnetic field configuration is arranged as a quasi-periodic domain in order to generalize the findings to all multipole discharges. The results show that the magnetic field strength drives the plasma structure, and the dependence on discharge power can be removed with proper scaling of the plasma parameters. The stronger magnetic field results in a higher peak plasma density, but relatively low discharge utilization efficiency. In addition, the potential measurements indicate the likely onset of discharge instability. In contrast, the weaker magnetic field, or baseline configuration, better uses the volume of the chamber. This leads to a higher and more uniform density near the downstream end of the discharge where ion extraction would occur, implying superior discharge utilization.

Hydrogen plasma diagnosis in penning ion source by optical emission spectroscopy

Penning-type discharge plasma ion source is a kind of powerful discharge device applied widely in many fields. In this paper, optical emission spectroscopy (OES) measurement is carried out to diagnose the parameters of hydrogen plasma in a miniature penning-type discharge ion source. The relative intensity of neutral atomic hydrogen emission spectral lines is used to evaluate the electron temperature of hydrogen plasma. The experiment results indicate that the relative intensity of Balmer-α, Balmer-β and Balmer-γ lines exhibits significant dependence on the filling gas pressure and the electron temperature is about 1.5–3 eV in the range of discharge current 30–180 μA when the anode voltage is fixed at 1.4 kV.

Anomalous behavior of optogalvanic signal in a miniature neon discharge lamp

A strong optogalvanic effect has been observed in a negative glow of a miniature neon discharge lamp using tunable pulse dye laser pumped by a copper vapor laser. A comparative study on temporal evolution of optogalvanic signal in a positive and negative dynamic resistance region of the discharge is described. Dye laser beam was tuned to various neon transitions 1si→2pj (Paschen notations) within 570–617nm wavelength range. Anomalous behavior of optogalvanic signal was observed at 588.2nm for (1s5→2p2) neon transition at low discharge current (<220μA). This anomalous behavior is the attributes of damped oscillations of optogalvanic signal that correlate with negative dynamic resistance (dV/di<0) of the discharge. Penning ionization at low discharge current and small energy mismatch is assumed to be the main cause of the negative dynamic resistance. Penning ionization process has been explained by resonantly ionizing energy transfer via collisions between neon buffer gas atoms in the lowest metastable state (1s5) and electrode sputtered atoms in ground state using their partial energy level diagram.

Surface Modification by Electric Discharge Implemented with Electrodes Composed of Carbon Nanotubes

In this work the electric discharge machining (EDM) implementing with multi-wall carbon nanotubes (MWCNT) as a miniscule electrode for pursuing precise surface modification was studied. The excellent upright growth of carbon nanotubes on copper based alloy substrates by a radio frequency (RF) assisted hot filament chemical vapor deposition (HFCVD) method suggests us to exploit MWCNTs as the miniature electrodes for discharge machining. The results reveal that the electrodes are much endurable to be distorted even when the spoiling rates for the polishing of n-type Si wafer (of 10 to approximately 100 omega-cm) are up to 30 nm/min with. It is expected that MWCNTs can be applied to non-conventional material processing especially in miniature discharge machining.

Two-dimensional simulation of a direct-current microhollow cathode discharge

Microhollow cathode discharges (MHCD’s) are miniature direct-current discharges that operate at elevated pressures (several tens to hundreds of Torr) with electrode dimensions in the 10–100-μm range. MHCD’s have been proposed for a number of applications based on their unique characteristics such as presence of intense excimer radiation and significant gas heating within the submillimeter discharge volume. A two-dimensional, self-consistent fluid model of a helium MHCD in the high-pressure (several hundreds of Torr), high-current (∼1mA) operating regime is presented in this study. Results indicate that the MHCD operates in an abnormal glow discharge mode with charged and excited metastable species with densities of ∼1020m−3, electron temperatures of approximately tens of eV, and gas temperatures of hundreds of Kelvin above room temperature. Significant discharge activity exists outside of the hollow region. The discharge volume and intensity increases with increasing current and becomes more confined with increasing pressures. Most predictions presented in this paper are in qualitative and quantitative agreement with experimental data for MHCD’s under similar conditions.

ミクロ反応場の生成と応用 -マイクロプラズマ研究の現状と将来展望- 2.マイクロプラズマの生成

We review methods of generating microplasamas and the issues involved in generating them efficiently such as developing miniature discharge circuits and active-functional electrodes. Because the size of plasmas is extremely small, new experimental schemes not common in conventional plasma apparatuses will be applicable. The microplasma discharges are established with solid, liquid, and gaseous matter. The pulsed power system is one of the effective ways to power the discharges, given that the electrical energy has to fill small volumes over relatively short time in order to avoid energy and particle losses. Nano-sized-structure and active-functional electrodes are developed to establish control of electrons, which is essential to obtain uniform and stable discharges.

Operation of a coplanar-electrode plasma display panel cell

Plasma display panels (PDPs) are composed of miniature gas discharge devices sustained in noble gas mixtures. In this paper, the dynamics of a coplanar-electrode PDP cell are described using results from a two-dimensional computer simulation. During the first voltage pulse, the discharge takes place between the top and bottom electrodes. Due to charging of the bottom dielectric during the first discharge pulse, a surface discharge takes place between the top coplanar electrodes on successive pulses.

A 1.5- mu m laser package frequency-locked with a novel miniature discharge lamp

The authors report a packaged distributed feedback (DFB) laser frequency-locked to the Kr 1s/sub 2/-2p/sub 8/ transition at 1.54782 mu m using a novel miniature discharge lamp. This transition is not only close to the wavelength where typical single-mode optical fibers show minimum attenuation but also gives a large optogalvanic signal. This lamp generates more than an order of magnitude larger optogalvanic signal for the same input power than conventional indicator lamps of comparable size. The frequency stability of the laser package is better than 2 MHz, and the fiber-to-laser coupling loss ( >

Ultrastructural changes in cockroach leg muscle following unilateral neurotomy. 2. Reaeneration

Neurotomized retractor unguis (R.u.) muscles of adult male cockroaches, Periplaneta americana, were examined electrophysiologically and ultrastructurally. Miniature excitatory postsynaptic potentials (min EPSPs) were recorded intracellularly for up to 96 hr after neuromuscular transmission had failed. The miniature discharge declined gradually during this period and by 4–6 days postneurotomy at 25°C the majority of muscles were electrically silent. Neither “bursts” nor “giant” miniature potentials were recorded from neurotomized muscles. The cessation of miniature discharge was correlated with glial cell engulfment of axon terminals. The occurrence of dense aggregates of synaptic vesicles in degenerating terminals was invariably accompanied by the isolation of such terminals from the aposynaptic apparati by glial cells. Following complete terminal degeneration, glial cells remained in close proximity to persistent aposynaptic apparati. However, there was no resumption of miniature activity without clear evidence of reinnervation having occurred. The neurotomized R.u. muscles showed a marked increase in glycogen granules during the first week and muscle dry weight measurements indicated a 15% hypertrophy during this period. During the second week following neurotomy, extensions from the R.u. muscle fiber developed at former junctional sites. These extensions possessed isolated cisternae of SR, dyads, microtubules, ribosomes, and glycogen granules. From about 12 days postneurotomy, specialized associations were observed between contiguous myofibers. These associations, considered to be adherens junctions, became more pronounced as muscle atrophy progressed and persisted until such time as the myofibers were reinnervated. By 20 days postneurotomy, a reduction in sarcoplasmic reticulum was apparent with a concomitant loss of myofibrillar substructure. At 30 days, mitochondrial breakdown and a loss of superficial myofilaments was evident and by 40 days postneurotomy, muscle dry weight had decreased by 35–40%. Muscle atrophy continued steadily thereafter providing that reinnervation did not occur.

Ultrastructural changes in cockroach leg muscle following unilateral neurotomy. I. Degeneration

Neurotomized retractor unguis (R.u.) muscles of adult male cockroaches, Periplaneta americana , were examined electrophysiologically and ultrastructurally. Miniature excitatory postsynaptic potentials (min EPSPs) were recorded intracellularly for up to 96 hr after neuromuscular transmission had failed. The miniature discharge declined gradually during this period and by 4–6 days postneurotomy at 25°C the majority of muscles were electrically silent. Neither “bursts” nor “giant” miniature potentials were recorded from neurotomized muscles. The cessation of miniature discharge was correlated with glial cell engulfment of axon terminals. The occurrence of dense aggregates of synaptic vesicles in degenerating terminals was invariably accompanied by the isolation of such terminals from the aposynaptic apparati by glial cells. Following complete terminal degeneration, glial cells remained in close proximity to persistent aposynaptic apparati. However, there was no resumption of miniature activity without clear evidence of reinnervation having occurred. The neurotomized R.u. muscles showed a marked increase in glycogen granules during the first week and muscle dry weight measurements indicated a 15% hypertrophy during this period. During the second week following neurotomy, extensions from the R.u. muscle fiber developed at former junctional sites. These extensions possessed isolated cisternae of SR, dyads, microtubules, ribosomes, and glycogen granules. From about 12 days postneurotomy, specialized associations were observed between contiguous myofibers. These associations, considered to be adherens junctions, became more pronounced as muscle atrophy progressed and persisted until such time as the myofibers were reinnervated. By 20 days postneurotomy, a reduction in sarcoplasmic reticulum was apparent with a concomitant loss of myofibrillar substructure. At 30 days, mitochondrial breakdown and a loss of superficial myofilaments was evident and by 40 days postneurotomy, muscle dry weight had decreased by 35–40%. Muscle atrophy continued steadily thereafter providing that reinnervation did not occur.