Anodic Phase Research Articles

Simultaneous separation and quantification of acidic and basic dye specimens via a dual gel electro-membrane extraction from real environmental samples

In this work, an environmentally friendly and easy-in-performance dual gel electro-membrane extraction approach (dual G-EME) was combined with high performance liquid chromatography. Method was arranged for parallel isolation, enrichment and determination of brilliant green (BG) and reactive red (RR), serving as model basic and acidic dyes, respectively. A DIY (do-it-yourself) agarose-based gel membrane was fabricated, and served as green and highly selective filtering item. The extractions were hazards-free (i.e., there was no need for organic solvents or toxic regents) and membrane assembly is highly degradable as being of fully natural character. Thereby, setup has met the requirements of being a green analytical chemistry technique. By using an electric potential of 50 V during 20 min extraction time, the positively charged BG and negatively charged RR migrated selectively from a 7.0 mL aqueous sample (pH 7.0) to the 500 μL cathodic (pH 4.0) and 500 μL anodic (pH 9.0) aqueous acceptor phases, respectively. Under the optimal conditions, limits of detection were 0.020 and 0.025 ng mL−1, and extraction recoveries were of 75–78% and 67–71% for BG and RR, respectively. The linearity was in the range of 0.06–1.0 μg mL−1 with correlation coefficient higher than 0.996, obtained for both model analytes. Finally, the methodology was successfully applied for parallel quantification of BG and RR in complex environmental samples.

Oxygen-reducing bidirectional microbial electrodes designed in real domestic wastewater

Microbial electrodes were designed in domestic wastewaters to catalyse the oxidation of organic matter (anode) and the reduction of oxygen (cathode) alternately. The successive aeration phases (cathode) enhanced the anodic efficiency, resulting in current densities of up to 6.4 Am−2 without the addition of any substrate. Using nitrogen during the anodic phases affected the microbial populations and the electrodes showed a lower ability to subsequently turn to O2 reduction than the microbial anodes formed in open-to-air conditions did. No strong difference was observed between internal and external biofilm, both of which showed a very large variety of taxa in terms of abundance as well as variance. They comprised a mix of aerobic and anaerobic species, many of which have already been identified separately in bioelectrochemical systems. Such a large diversity, which had not been observed in aerobic bidirectional bioelectrodes so far, can explain the efficiency and robustness observed here.

High-Tension Closure of the Submental Flap Donor Site: Video and Technical Considerations.

Most cochlear implants (CIs) stimulate the auditory nerve with trains of symmetric biphasic pulses consisting of two phases of opposite polarity. Animal and human studies have shown that both polarities can elicit neural responses. In human CI listeners, studies have shown that at suprathreshold levels, the anodic phase is more effective than the cathodic phase. In contrast, animal studies usually show the opposite trend. Although the reason for this discrepancy remains unclear, computational modelling results have proposed that the degeneration of the peripheral processes of the neurons could lead to a higher efficiency of anodic stimulation. We tested this hypothesis in ten guinea pigs who were deafened with an injection of sysomycin and implanted with a single ball electrode inserted in the first turn of the cochlea. Animals were tested at regular intervals between 1 week after deafening and up to 1 year for some of them. Our hypothesis was that if the effect of polarity is determined by the presence or absence of peripheral processes, the difference in polarity efficiency should change over time because of a progressive neural degeneration. Stimuli consisted of charge-balanced symmetric and asymmetric pulses allowing us to observe the response to each polarity individually. For all stimuli, the inferior colliculus evoked potential was measured. Results show that the cathodic phase was more effective than the anodic phase and that this remained so even several months after deafening. This suggests that neural degeneration cannot entirely account for the higher efficiency of anodic stimulation observed in human CI listeners.

Impact of magnetic field on corrosion performance of Al–Mg alloy with different electrode potential phases

We investigated the influence of magnetic field on the corrosion performance of Al-3.0 Mg-xRE/Fe alloys using microstructure observation, immersion test, electrochemical measurement, and pH and conductivity tests. The effects of both magnetic field and the change in the solution properties on the corrosion performance of Al-3.0 Mg alloy with different phases were discussed. The results indicated that the application of magnetic field in 3.5 wt% NaCl solution can reduce the pitting sensibility and corrosion rate of Al-3.0 Mg-xRE/Fe alloys. However, magnetic field treatment could also lead to the increase in the pH and conductivity of NaCl solution. The application of magnetic field can cause changes in the solution properties, thus changing the corrosion rate of Al-3.0 Mg alloy with different phases. The effect of magnetic field on the corrosion performance of Al-3.0 Mg-xRE/Fe alloys was due to the appearance of paramagnetic gradient force/magnetohydrodynamic flow and the change of solution properties during the corrosion process. Magnetic field had different effects on the corrosion behavior of Al-3.0 Mg alloys with different electrode potential phases. The appearance of paramagnetic gradient force/magnetohydrodynamic flow and the change of solution properties under magnetic field both reduced the corrosion rate of Al-3.0 Mg-xRE alloys (with anode phases). However, for Al-3.0 Mg xFe alloys (with cathode phases), the paramagnetic gradient force/magnetohydrodynamic flow induced by magnetic field reduced the corrosion rate of the alloys, while the change of solution properties under MFT accelerated the corrosion process.

Performance of Titanium Nitride Electrodes Used for Chronic Peripheral Nerve Stimulation

Electrical stimulation of the nervous system is used clinically to treat diseases such as epilepsy and there is increasing research using electrical stimulation to treat diseases and disorders where traditional pharmaceuticals are not effective. The performance of a device used for neural stimulation depends on its ability to reliably transfer the necessary charge to elicit a physiological response in a manner that is safe for both the tissue and electrode.Electrode materials that transfer charge via faradaic and non-faradaic mechanisms are used for neural stimulation. Electrodes that deliver charge via faradaic processes can accommodate the high amplitudes required for stimulation, but the faradaic reactions change the chemical composition of the surrounding tissue. Electrodes that deliver charge by charging and discharging the capacitive double layer typically deliver less charge than faradaic electrodes, however, they are attractive for neural stimulation because they do not change the chemical composition of the surrounding tissue. Titanium nitride (TiN) is an electrode material that has been used for non-faradaic charge transfer. This work evaluates the performance of TiN electrodes used for chronic peripheral nerve stimulation. To discriminate between electrode changes due to the chronic implantation versus stimulation, a separate set of TiN electrodes were subjected to continuous current-controlled biphasic pulsing in vitro. Methods: Nerve cuffs having four 0.39 mm2 rectangular TiN electrode sites were implanted around the cervical vagus nerve of male Brown Norway rats. The experimental procedures complied with the guidelines for the care and use of laboratory animals and were approved by the University of Florida Institutional Animal Care and Use Committee. Animals were chronically stimulated using current-controlled, charge-balanced biphasic cathode leading pulses. All electrochemical measurements were made with an Autolab potentiostat (PG- STAT12, Eco Chemie, Utrecht, The Netherlands). Electrochemical Impedance Spectroscopy (EIS) was measured using a cuff electrode site as the working electrode, and a bone screw as the reference and counter electrode. The Open Cell Potential (OCP) was measured prior to each measurement and was used as the pseudo zero for the EIS 20 mV peak-to-peak sinusoidal perturbation (wave type = 15 sines). The frequency was swept logarithmically downward from 100kHz to 50Hz. The in vitro electrical aging was performed on a separate set of TiN electrodes with the same specifications that were used in vivo. The electrodes were subjected to continuous current-controlled biphasic pulsing to replicate the amount of charge delivered over the lifetime of an implanted electrode. EIS and cyclic voltammetry (CV) were measured periodically throughout the pulsing. Results: The impedance magnitude increased over the duration of implantation for all animals. However, there appeared to be no relation between the impedance magnitude and amount of stimulation applied.The electrode potential was measured throughout the pulsing and showed a gradual increase over time in the electrode polarization during the anodic and cathodic phases. Electrochemical impedance spectroscopy and cyclic voltammetry were taken periodically throughout the pulsing and showed progressive changes in charge transfer for stimulated electrodes (figure 1B,C) , whereas electrode sites not subjected to stimulation had minimal changes (figure 1A). Stimulated electrodes also showed signs of electrode damage, such as delamination, that were not observed for unstimulated electrodes. Conclusion: Future work will focus on additional analysis of explanted cuffs to directly measure the influence of the in vivo environment. Figure 1

Subthreshold Electrical Stimulation for Controlling Protein-Mediated Impedance Increases in Platinum Cochlear Electrode.

This study evaluated subthreshold biphasic stimulation pulses as a strategy to stabilize electrode impedance via control of protein adsorption. Following implantation, cochlear electrodes undergo impedance fluctuations thought to be caused by protein adsorption and/or inflammatory responses. Impedance increases can impact device power consumption, safe charge injection limits, and long-term stability of electrodes. Protein-mediated changes in polarization impedance (Zp) were measured by voltage transient responses to biphasic current pulses and electrochemical impedance spectroscopy, with and without protein solutions. Four subthreshold stimulation regimes were studied to assess their effects on protein adsorption and impedance; (1) symmetric charge-balanced pulses delivered continuously, (2) at 10% duty cycle, (3) at 1% duty cycle, and (4) an asymmetric charge balanced pulse delivered continuously with a cathodic phase twice as long as the anodic phase. The Zp of electrodes incubated in protein solutions without stimulation for 2 h increased by between ∼28% and ∼55%. Subthreshold stimulation reduced the rate at which impedance increased following exposure to all protein solutions. Decreases in Zp were dependent on the type of protein solution and the stimulation regime. Subthreshold stimulation pulses were more effective when delivered continuously compared to 1% and 10% duty cycles. These results support the potential of subthreshold stimulation pulses to mitigate protein-mediated increase in impedance. This research highlights the potential of clinically translatable stimulation pulses to mitigate perilymph protein adsorption on cochlear electrodes, a key phenomenon precursor of the inflammatory response.

Degradation study of a proton exchange membrane water electrolyzer under dynamic operation conditions

Understanding degradation phenomena of polymer electrolyte water electrolyzers operating under dynamic conditions is imperative for developing and implementing efficient and reliable means of energy storage from fluctuating and intermittent renewable energy sources. Herein, a commercial membrane electrode assembly with an amorphous IrOx anode is subjected to potential sweeping (1.4–1.8 V) with short and long holds and few steady-state interims for overall 830 h at 60 °C and ambient pressure to simulate frequent alternating idle and nominal operation regimes. Systematic electrochemical diagnostics and physicochemical methods are applied to identify degradation sources. Mild kinetic deactivation (2.6 μV/h) is observed independent on the dynamic protocol, due to loss of electrochemical surface area via crystallization. The amount of Ir dissolved and redeposited in the ionomer anode phase and in the membrane is negligible in comparison to the current state-of-the-art Ir loadings. As compared to kinetic losses, the irreversible resistive losses are one order of magnitude higher and are thought to be caused by the degradation of the membrane close to the anode catalyst layer. These resistive losses are associated specifically with dynamic operation. The two orders of magnitude higher, but recoverable, degradation during steady-state interims is attributed to the growth of inhibiting or long-lived species.

Improving control effects of absence seizures using single-pulse alternately resetting stimulation (SARS) of corticothalamic circuit

Presently, we develop a simplified corticothalamic (SCT) model and propose a single-pulse alternately resetting stimulation (SARS) with sequentially applying anodic (A, “+”) or cathodic (C, “−”) phase pulses to the thalamic reticular (RE) nuclei, thalamus-cortex (TC) relay nuclei, and cortical excitatory (EX) neurons, respectively. Abatement effects of ACC-SARS of RE, TC, and EX for the 2Hz–4Hz spike and wave discharges (SWD) of absence seizures are then concerned. The m:n on-off ACC-SARS protocol is shown to effectively reduce the SWD with the least current consumption. In particular, when its frequency is out of the 2 Hz–4Hz SWD dominant rhythm, the desired seizure abatements can be obtained, which can be further improved by our proposed directional steering (DS) stimulation. The dynamical explanations for the SARS induced seizure abatements are lastly given by calculating the averaged mean firing rate (AMFR) of neurons and triggering averaged mean firing rates (TAMFRs) of 2Hz–4Hz SWD.

Fiber Threshold Accommodation as a Mechanism of Burst and High-Frequency Spinal Cord Stimulation

Burst and high-frequency spinal cord stimulation (SCS), in contrast to low-frequency stimulation (LFS, < 200 Hz), reduce neuropathic pain without the side effect of paresthesia, yet it is unknown whether these methods' mechanisms of action (MoA) overlap. We used empirically based computational models of fiber threshold accommodation to examine the three MoA. Waveforms used in SCS are composed of cathodic, anodic, and rest phases. Empirical studies of human peripheral sensory nerve fibers show different accommodation effects occurring in each phase. Notably, larger diameter fibers accommodate more than smaller fibers. We augmented our computational axon model to replicate fiber threshold accommodation behavior for diameters from 5 to 15 μm in each phase. We used the model to predict threshold change in variations of burst, high frequency, and LFS. The accommodation model showed that 1) inversion of larger and smaller diameter fiber thresholds produce a therapeutic window in which smaller fibers fire while larger ones do not and 2) the anodic pulses increase accommodation and perpetuate threshold inversion from burst to burst and between cathodic pulses in burst, high frequency, and variations, resulting in an amplitude "window" in which larger fibers are inactivated while smaller fibers fire. No threshold inversion was found for traditional LFS. The model, based on empirical data, predicts that, at clinical amplitudes, burst and high-frequency SCS do not activate large-diameter fibers that produce paresthesia while driving medium-diameter fibers, likely different from LFS, which produce analgesia via different populations of dorsal horn neural circuits.

Effect of Solution Temperature on the Corrosion Behavior of 6061-T6 Aluminum Alloy in NaCl Solution

The influence of solution temperature on the corrosion behavior of 6061-T6 aluminum alloy in 3.5% NaCl solution was studied by electrochemical tests, weight loss method, and surface morphology analysis. The results show that the samples treated at different solution temperatures have different corrosion resistance. The anticorrosion resistance of aluminum alloys decreases first and then increases as the solution temperature increases. At 535 °C, the sample has the optimal corrosion resistance, with a slight corrosion degree, while the alloy sample treated at 555 °C shows the most severe degree of corrosion, with a large number of different sized pits and some ulcerous corrosion pits, as well the apparent intergranular corrosion. The corrosion behavior of different solid aluminum alloy samples is closely related to the microstructure. The Mg2Si precipitates act as the anode phase to protect the substrate, and a decrease in the amount of AlFeSi precipitates reduces the number of micro-galvanic corrosion cells, and the severe segregation of AlFeSi precipitates accelerates the corrosion.

Microstructural, Morphological and Electrochemical Effects of Graphene Oxide Incorporation in Tin-Cobalt Composite Coatings

Effect of incorporation of graphene oxide (GO) on the evolution of morphology, phase constitution, microstructure and corrosion properties of SnCo-GO composite coating was investigated. SnCo-GO composite coatings containing different amounts of graphene oxide were electrodeposited over mild steel substrate using electrolyte with different concentrations of dispersed graphene oxide (0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.5, 0.625 g/L). Morphological examination revealed that lesser additions of GO increased the coating compactness and uniformity whereas higher amounts of GO produced surface defects in the composite coatings. Structural characterization revealed the presence of primarily two different intermetallic phases in the coating microstructure: Co2Sn phase and Co3Sn2 phase. It was observed that the phase fraction of the relatively more inert Co3Sn2 phase increased monotonically with increase in the amount of GO in the coatings. Microstructural investigations revealed that in the pristine SnCo coating the Co2Sn phase is present at the grain boundaries of the Co3Sn2 phase grains. Incorporation of GO altered the coating microstructure considerably leading to the formation of a layered microstructure where the elongated Co2Sn phase grains were present beneath laterally elongated grains of the Co3Sn2 phase. Electrochemical analysis performed using the Tafel polarization and impedance spectroscopy measurements showed that the corrosion properties of the coating were highly sensitive to the amount of GO present in the coating. Initial addition of GO increased the corrosion resistance till an optimum GO concentration for which highest corrosion resistance was achieved. Further addition of GO beyond the optimum lead to monotonic decrease in the corrosion resistance to values which were lower than the pristine SnCo coating. Initial increase in the corrosion resistance was attributed to uniform distribution of GO in the coating, increase in the uniformity and compactness of the coatings, increase in the fraction of the relatively more inert Co3Sn2 phase in the coating microstructure and formation of a layered microstructure in which the exposed coating surface contained the relatively more inert Co3Sn2 phase. Decrease in the corrosion resistance beyond the “optimum” was due to increase in the coating surface defects due to the deposition of agglomerated GO and galvanic coupling due to increase in the cathodic (GO) to anodic (metal) phase area.

Advances in High-Throughput in-Situ X-Ray Diffraction Analysis of Lithium Ion Batteries

X-ray diffraction using hard radiation (>17 keV) is able to measure lattice parameter and phase changes of cathode and anode materials simultaneously during battery cycling. Advances in hard radiation optics and detectors, combined with data logging software to correlate diffractometer and potentiostat data, are being used to improve in-situ battery analysis using laboratory diffractometers. Research previously done at synchrotrons can now be conducted with the laboratory diffractometer, improving opportunities for long-term experimental design. In this study, a reversible displacive phase transition in NMC cathodes, marked by significant contraction of the unit cell, is observed during cycling at a modest 4.2V potential. The magnitude of lattice contraction is dependent on the Ni content. This phase transition appears distinct from the H1 to H2 phase transition. Quantitative Rietveld anlaysis is used to precisely track lattice parameter changes in the cathode material. Because transmission diffraction measures cathode and anode simultaneously, anode phase content is quantified between C, LiC12, and LiC6 and these quantities are correlated to behavior of the cathode.

Impact of rare-earth elements on the corrosion performance of binary magnesium alloys

The corrosion behaviour of Mg-0.3Ce, Mg-0.41Dy, Mg-0.63Gd, Mg-1.44Nd and Mg-1.43La (wt.%) alloys in 3.5 wt% NaCl solution was investigated using electrochemical tests. The as-cast microstructures of the Mg-RE alloys were characterized by the presence of second phases (MgxCe, Mg41Dy5, Mg12Gd, Mg12Nd, Mg41Nd5, Mg24Nd and Mg12La) with different volume fraction and distribution. Results show that the corrosion mechanism was altered from uniform to localized corrosion mechanism depending on the specific RE alloying elements. The corrosion resistance of the Mg-RE alloys is increasing in the following order: Mg-1.43La, Mg-1.44Nd, Mg-0.3Ce, Mg-0.63Gd and Mg-0.41Dy. Accordingly, the corrosion morphology in the best resistant Mg-0.41Dy alloy and the worst Mg-1.43La alloy were observed and compared after 2h and 24 h of immersion using SEM-EDS, XPS and XRD analysis. The formation of the Dy2O3 oxide prevents the Mg-0.41Dy alloy from pitting corrosion and lead to an excellent corrosion surface even after 24 h of immersion. Meanwhile, the presence of a high fraction of the Mg12La phase along the grains boundaries in the Mg-1.43La alloy causes severe pitting corrosion by acting as anodic phase.

Incorporating Fe into Bismuthic Anode Systems: A Smart "Merits Combination/Complementation" Route to Build Better Ni-Bi Batteries.

The advancement of Ni-Bi batteries has turned sluggish because of impenetrable barriers related to physicochemical instability of bismuthic species under thermal conditions. This directly makes Bi-based anodes impossible to hybridize with graphitic carbons for a longer-term cyclic lifespan. To break this constraint, we herein propose an effective strategy by incorporating Fe into bismuthic systems to form multielement anodes. The smart Bi/Fe merits combination/complementation can drastically promote the tolerable temperature of Bi-containing nanomaterials over 500 °C, enabling carbon encapsulation without altering their geometric properties and in the meantime endowing the anodes with inherited electrochemical superiorities. The as-built BiFeO3@carbon anodes exhibit prominent electrode performances with excellent electrochemical activity (both Bi- and Fe-based components act as faradaic redox reaction sites), excellent rate capabilities, and impressive capacity retention (∼83.4% after 2000 cycles). We further unveil the anodic phase conversions of "BiFeO3 → Bi2O3/Fe2O3" (via the transition state of Bi2O3(222)) based on the real-time characterizations/post-analysis at distinct cyclic stages. The packed full cells exhibit max. energy/power densities of ∼90.72 W h kg-1/∼1.3 kW kg-1. Our study may offer a promising engineering route to promote the development of safe and applicable Ni-Bi batteries in near-future applications.

Effects of Ag+ in diaphragm electrolysis on oxygen evolution and corrosion behaviors of Pb and Pb[sbnd]Ag anodes

In this study, the effects of Ag+ (140 mg/L) in an electrolyte on the oxygen evolution and corrosion behaviors of Pb and PbAg (0.6 wt%) anodes in diaphragm electrolysis were investigated by utilizing a variety of tests and analyses, including galvanostatic polarization, mass increment, ion concentration, anodic polarization curve, phase analysis, and scanning electron microscopy of the oxide layer and substrate. The results show that an ion exchange membrane can effectively prevent Ag+ and Pb2+ from penetrating into the cathode chamber and depositing on the cathode. The addition of Ag+ in diaphragm electrolysis significantly lowers the overpotential of oxygen evolution reaction and improves the corrosion resistance of Pb and PbAg (0.6 wt%) anodes. This is mainly attributed to the formation of Ag2O2 on the surface of the anode, which provides good catalytic activity for the oxygen evolution reaction (Ag2O2 can form Ag2O2 hydrate in sulfuric acid solution, Ag2O2 hydrate loses electrons and H+ during electrification, and then Ag2O2 is formed again after electron rearrangement).

The Effect of Sub-Threshold Pre-Pulses on Neural Activation Depends on Electrode Configuration.

Published research on nerve stimulation with sub-threshold conditioning pre-pulses is contradictory. Like most early research on electrical stimulation (ES), the pioneer work on the use of pre-pulses was modelled and measured only for monopolar electrodes. However, many contemporary ES applications, including miniaturized neuromodulation implants, known as electroceuticals, operate in bipolar mode. We compared depolarizing (DPPs) and hyperpolarizing (HPPs) pre-pulses on neural excitability in rat nerve with monopolar and bipolar electrodes. The rat common peroneal nerve was stimulated with biphasic stimuli with and without ramp and square DPPs or HPPs of 1, 5 and 10ms duration and 10%-20% of the amplitude of the following pulse. The effects were opposite for the monopolar and bipolar configurations. With monopolar electrodes DPPs increased the amplitude required to activate 50% of the motoneuron pool (between 0.7% and 10.3%) and HPPs decreased the threshold (between 1.7% and 4.7%). With bipolar electrodes both pre-pulse types had the opposite effect: DPPs decreased thresholds (between 1.8% and 5.5%) whereas HPPs increased thresholds (between 0.5% and 4.1%). Electroneurograms from the stimulated nerve revealed spatial and temporal differences in action potential generation for monopolar and bipolar electrodes. In bipolar biphasic stimulation, excitation first occurred at the return electrode as a response to the transition between the cathodic and anodic phase. These data help to resolve the contradictions in the published data over two decades. They also show that fundamental research carried out in monopolar configuration is not directly applicable to contemporary bipolar ES applications.

Effects of Zn content on microstructure, mechanical and degradation behaviors of Mg-xZn-0.2Ca-0.1Mn alloys

In this study, the microstructure characterization, mechanical properties and degradation behaviors of the Mg-xZn-0.1Mn-0.2Ca alloys with various Zn contents were analyzed via the polarization test, electrochemical impedance spectroscopy and the static immersion measurements. Meantime, the surface film layer features and the phase constitutions of the degradation production were characterized via the confocal laser scanning microscopy (3D/CLSM) and scanning electron microscopy. The results indicated that the more secondary phases appeared and the grain sizes were remarkably refined with the further addition of Zn, such as the Ca2Mg6Zn3, Mg2Ca and Mg4Zn7. The mechanical and corrosion resistance of the Mg-xZn-0.1Mn-0.2Ca alloys both initially increased and then decreased as Zn contents increased. Besides, the special anodic phase has been detected in the interior of the matrix, where the Mg2Ca phase with the lower potentials can protect Mg matrix from dissolving in the simulated body fluids (SBF). However, the Ca2Mg6Zn3 phase with the high potentials can accelerate dissolution rate of the Mg matrix. The best mechanical properties and corrosion resistance were obtained in the Mg–1Zn-0.1Mn-0.2Ca alloys, with the corrosion rate of 6.09 mm/y, exhibiting the uniform degradation morphology.

Electrical Stimulation of C6 Glia-Precursor Cells In Vitro Differentially Modulates Gene Expression Related to Chronic Pain Pathways.

Glial cells comprise the majority of cells in the central nervous system and exhibit diverse functions including the development of persistent neuropathic pain. While earlier theories have proposed that the applied electric field specifically affects neurons, it has been demonstrated that electrical stimulation (ES) of neural tissue modulates gene expression of the glial cells. This study examines the effect of ES on the expression of eight genes related to oxidative stress and neuroprotection in cultured rodent glioma cells. Concentric bipolar electrodes under seven different ES types were used to stimulate cells for 30 min in the presence and absence of extracellular glutamate. ES consisted of rectangular pulses at 50 Hz in varying proportions of anodic and cathodic phases. Real-time reverse-transcribed quantitative polymerase chain reaction was used to determine gene expression using the ∆∆Cq method. The results demonstrate that glutamate has a significant effect on gene expression in both stimulated and non-stimulated groups. Furthermore, stimulation parameters have differential effects on gene expression, both in the presence and absence of glutamate. ES has an effect on glial cell gene expression that is dependent on waveform composition. Optimization of ES therapy for chronic pain applications can be enhanced by this understanding.

Effect of Microstructure on the Corrosion Resistance of TIG Welded 1579 Alloy.

The paper studies microstructure, chemical composition and corrosion activity of the tungsten inert gas welded joint of the Al-Mg-Sc alloy. An intensive corrosion attack of the heat affected zone (HAZ) was found due to precipitation of secondary phases at recrystallized grain boundaries. The ccorrosion process initiated along the boundary of α-Al grains, where a high concentration of anodic (Mg2Si and Mg2Al3) and cathodic phases ((MnFe)Al6) was observed. Increased temperatures during welding led to coalescence of the anodic phases in HAZ. Additionally, HAZ was found to be enriched with hard intermetallic compounds (Mg2Si and (MnFe)Al6). This area had a higher microhardness (930 MPa) compared to base metal (BM, 895 MPa) and fusion zone (FZ, 810 MPa). The volume fraction of secondary phases was 26% in BM, 28% in FZ and 38% in HAZ. The average grain size increased in the following order: (9 ± 3) µm (BM) < (16 ± 3) µm (HAZ) < (21 ± 5) µm (FZ). A plasma electrolytic oxidation (PEO) coating of aluminum-based material was applied to protect the weld from oxidation. The PEO-coating provided a high corrosion protection in the aggressive Cl−-containing environment.

Determination of Cr(III) and Cr(VI) in water by dual-gel electromembrane extraction and a microfluidic paper-based device

A major goal of green chemistry is to avoid the use of toxic organic solvents. In particular, there are few green methods allowing extraction and quantification of chromium species in environmental samples. Here, we developed home-made, dual-gel electromembrane extraction combined with a microfluidic paper-based analytical device for the simultaneous determination of Cr(III) and Cr(VI) in water, without using any organic solvent. The positively charged Cr(III) and negatively charged Cr(VI) migrated selectively into the cathodic (pH 2.0) and anodic (pH 3.0) aqueous acceptor phases, respectively. After extraction, the anodic acceptor phase containing Cr(VI) was analyzed directly by a microfluidic paper-based analytical device, after the addition of the diphenylcarbazide colorimetric reagent. The cathodic acceptor phase containing Cr(III) was mixed with Ce(IV) to oxidize Cr(III) to Cr(VI), and then, Cr(VI) ions were detected on the microfluidic paper-based analytical device after adding diphenylcarbazide. Under the optimized conditions, limits of detection of 2.0 and 3.0 ng/mL and extraction recoveries of 58.8% and 83.3% were achieved for Cr(VI) and Cr(III), respectively.