[Rapid detection of four amphetamine-type drugs in hair by pulsed direct current electrospray mass spectrometry].

Amphetamine-type drugs are synthetic compounds with an amphetamine parent structure. These compounds cause addiction, central nervous system excitation, and hallucinations. The number of drug users worldwide has gradually increased because amphetamine-type drugs can be synthesized in a simple and artificial manner. The current methods for anti-drug screening and toxicant identification are limited by the large quantity and variety of the drug analytes and long detection times. Thus, the development of broad-spectrum, rapid, and high-throughput detection methods is an urgent necessity. In addition, conventional amphetamine-type drug test samples, such as blood and urine, are only suitable for short-term drug identification. Hair has the advantages of easy preservation, stability, and a long detection window, which can compensate for the deficiencies of body-fluid-based test materials. Hair samples can reflect long-term drug use, which is beneficial for tracing drug sources, and has become an important means of providing evidence in court. Because most laboratory instruments are unable to perform the rapid on-site detection of amphetamine-type drugs in hair, establishing a high-throughput, qualitative and quantitative rapid on-site detection method is necessary. In this study, pulsed direct current electrospray ionization (Pulsed-DC-ESI) coupled with mass spectrometry was used for the rapid detection of four amphetamine-type drugs (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxymethamphetamine) in hair. Methanol was used as the extraction solvent, and the grinding method was used for extraction. The pretreatment process included cutting, grinding, and centrifugation. The pretreatment time for each sample was about 10 min. Multiple samples could be processed in batches, greatly improving the efficiency of analysis. Pulsed-DC-ESI is an ambient ionization technology that can be conducted via direct injection without chromatographic separation. The tip of the spray capillary tube was immersed 1 cm below the surface of the sample solution to allow absorption via the capillary effect. When the spray capillary tube contained 1 µL of the sample solution, detection was performed. Pulsed-DC-ESI generates an electrospray at the same frequency as the mass spectrum, thereby avoiding the problem of sample wastage, which often occurs in traditional ESI. The portable mass spectrometer used for analysis is a linear ion trap mass spectrometer. The parameters of Pulsed-DC-ESI, such as the inner diameter of spray capillary tip, spray voltage, and distance between electrode and solution, were optimized based on the mass spectral responses of the amphetamine-type drugs. The optimized ion source conditions included a inner diameter of spray capillary tip of 25 µm, spray voltage of 2 kV, and the distance between electrode and solution of 20 mm. The optimal sample solvent was methanol. The optimized method can achieve simultaneous detection of the four amphetamine-type drugs within 20 s. The linear ranges of amphetamine, methamphetamine, and the two other drugs were 1-25, 1-100, and 1-50 ng/mg, respectively. The limits of detection and quantification of the four drugs in hair were 0.1-0.2 and 1 ng/mg, respectively. All linear correlation coefficients were greater than 0.99, and the average spiked recoveries were 86.6%-114.7%. The intra-day precisions were 4.14%-7.34%, and the inter-day precisions were 3.71%-8.43%. The proposed method was used to screen 2000 samples provided by various testing institutions. A total of five samples were positive for methamphetamine, which is consistent with the results of conventional forensic identification methods. Thus, the developed method can be used for the rapid detection of amphetamine-type drugs.

The acute muscular response following a novel form of pulsed direct current stimulation (Neubie) or traditional resistance exercise.

OBJECTIVES: To examine changes in muscle thickness (MT), soreness (SOR), and isometric torque (ISO) following exercise with pulsed direct current (Neubie) or traditional high-load (TRAD) exercise. METHODS: Thirty-two participants had SOR, MT, and ISO measured before, immediately after, and 24 and 48h following TRAD and Neubie. Rating of perceived exertion (RPE) and discomfort were also measured. Results are displayed as means(SD). RESULTS: For MT, there was a condition x time interaction (p<0.001). For Neubie, MT increased pre [3.7(0.7)cm] to post [3.9(0.8) cm, p<0.001] and remained elevated at 24h. For TRAD, MT increased pre [3.7(0.6)cm] to post [4.0 (0.7)cm, p<0.001] and remained up to 48h. Greater values were observed for TRAD post-exercise. For ISO, both conditions decreased up to 48h. TRAD demonstrated a greater change post exercise (p<0.001). For SOR, both conditions increased up to 48h. Neubie demonstrated greater SOR at 48h (p=0.007). RPE was higher for all sets in TRAD [Mean across sets=16.0(1.9) vs. 13.5(2), p<0.001]. Discomfort was higher in all sets for Neubie [Mean across sets=5.8(1.5)vs. 4.5(2.0), p<0.05]. CONCLUSIONS: Both conditions showed increased SOR, and decreased ISO for up to 48h, with MT increased for up to 24h. MT remained elevated in TRAD at 48h. Neubie training might be effective for individuals who are looking to experience lower RPE responses during exercise.

Effect of Pulsed Direct Current on Iontophoretic Delivery of Pramipexole across Human Epidermal Membrane In Vitro.

PURPOSE: Pulsed direct current (PDC) iontophoresis, by allowing skin depolarization, was suggested to provide more efficient ion transport, but the extent of its enhancement effect was unclear. PDC could also offer electric-customized drug delivery. This study examined the effect of PDC iontophoresis on transdermal delivery of pramipexole dihydrochloride (PXCl). METHODS: Iontophoretic delivery of PXCl across human epidermal membrane from pH 7.0 solution was conducted in vitro using continuous direct current (DC) and 6- and 12-cycle PDC iontophoresis (0.5 mA/cm2 and total applied duration of 6 h). Different parameters of PDC iontophoresis were studied, including current density (0.1, 0.2 and 0.5 mA/cm2) and on-off current dosing pattern (1 h/3 h, 0.5 h/3.5 h, and 0.2 h/3.8 h). RESULTS: Both 6- and 12-cycle PDC iontophoresis protocols provided modulation of the permeation profile but delivered smaller amounts of PXCl (396 and 400 µg/cm2, respectively) as compared with continuous DC iontophoresis (482 µg/cm2) at 24 h after 0.5 mA/cm2 and 180 mA/cm2 × min current dose application. Increasing applied current density from 0.1 to 0.5 mA/cm2 increased the PDC iontophoretic flux of PXCl linearly from 5.3 to 14.6 µg/cm2·h (R2 = 0.887). Varying the current level and duration but at the same applied current dose (36 mA/cm2 × min), the total amount of PXCl delivered by PDC iontophoresis at 24 h was independent of the on-off dosing pattern studied (114-128 µg/cm2). CONCLUSIONS: The results indicate that PDC iontophoresis can benefit transdermal delivery of PXCl in terms of controlling its permeation but does not enhance iontophoretic transport compared to continuous DC iontophoresis under the conditions studied.

Improved Degradation Efficiency of Levofloxacin by a Self-Powered Electrochemical System with Pulsed Direct-Current.

With the excellent structural design, rotary triboelectric nanogenerator (R-TENG) is suitable for harvesting mechanical energy such as wind energy and water energy to build a self-powered electrochemical system for environmental science. The electrochemical performance has been greatly improved by using the pulsed direct-current (PDC) output of a TENG; however, a full-wave PDC (FW-PDC) is hardly realized in R-TENG devices due to existence of phase superposition. Here, a R-TENG with FW-PDC output is reported to perform a self-powered electro-Fenton system for enhancing the removal efficiency of levofloxacin (OFL). By adjusting the rotation center angle ratio between each rotator and stator unit, the phase superposition of R-TENG caused by multiple parallel electrodes can be effectively eliminated, thus achieving the desired FW-PDC output. Because of the reduced electrode passivation effect, the removal efficiency of OFL is improved by 30% under equal electric charges through using the designed R-TENG with FW-PDC output compared to traditional R-TENG. This study provides a promising methodology to improve the performance of self-powered electrochemical process for treating environment pollutions.

Effect of the type of electrical stimulation on spinal fusion in a rat posterolateral spinal fusion model.

BACKGROUND CONTEXT: Posterolateral fusion (PLF) with autogenous iliac bone graft is one of the most common surgical procedures for lumbar spinal disease. However, its limited success demands new biologically competent graft enhancers or substitutes. Although the use of direct current (DC) electrical stimulation has been shown to increase rate of successful spinal fusions, little is known about the effect of the type of current in DC stimulation. PURPOSE: To evaluate the effects of various DC stimulators on the strength and success rate of posterolateral fusion facilitated by using a nitinol mesh container, in rats. STUDY DESIGN: This was an experimental animal study. METHODS: A conductive, tubular nitinol mesh container was used to carry small pieces of bone grafts. The nitinol mesh container received electrical stimulation via a lead that connected the container to different types of DC stimulators. Sixty male Sprague-Dawley rats were divided into three groups (N=20 in each): a control group that underwent PLF with a nitinol container filled with autograft, a constant DC group that received a nitinol container and constant DC (100 µA), and a pulsed DC group that received a nitinol container and pulsed DC (100 µA, 100 Hz, 200 µs). The rats underwent PLF between L4 and L5, and transverse processes were grafted with bilateral iliac grafts. A stimulator was implanted subcutaneously. The rats were sacrificed 8 weeks postsurgery, and lumbar spines were removed. Spinal fusion was evaluated by microcomputed tomography, manual testing, biomechanical testing, histologic examination, and molecular analysis. RESULTS: All animals in the DC stimulation groups displayed solid fusion, whereas only 70% of control animals showed solid fusion. Radiographic images, biomechanical testing, histologic examination, and molecular analysis revealed improved fusion in the order control group

Delineamento Box-Behnken para remoção de DQO de efluente têxtil utilizando eletrocoagulação com corrente contínua pulsada / Box-Behnken design for COD removal of textile wastewater using electrocoagulation with pulsed DC

RESUMO A remoção de poluentes de efluentes industriais de forma efetiva e economicamente viável ainda é um desafio. Dessa forma, o presente trabalho propôs investigar a tecnologia de eletrocoagulação (EC) para o tratamento de efluente têxtil utilizando corrente contínua pulsada (CCP). A metodologia de superfície de resposta Box-Behnken foi utilizada para analisar e otimizar as condições operacionais, visando à máxima remoção de demanda química de oxigênio (DQO). Os experimentos foram realizados com um volume reacional de 2,6 L, em modo batelada. Diante dos resultados obtidos, a configuração ótima considerada foi: velocidade de agitação = 200 rpm, frequência dos pulsos = 1.000 Hz e espaçamento entre os eletrodos = 1 mm, em 50 minutos de EC. Nessas condições foi obtida uma remoção de DQO de 81,23% (valor remanescente de 152 mg O2.L-1). Em adição, verificou-se que o processo de EC também é eficaz para a redução de cor, turbidez, sólidos suspensos totais, sulfato e sulfeto. A concentração de íons cloreto não foi alterada durante a EC, apresentando-se como um aspecto favorável para a reutilização do efluente tratado no próprio processo produtivo têxtil, o qual demanda uma elevada concentração de NaCl.

ABSTRACT The effective and economically viable removal of industrial wastewater pollutants is still a challenge. Thus, this study proposed to investigate the electrocoagulation technology (EC) for the treatment of textile effluent using pulsed direct current (CCP). The methodology of Box-Behnken response surface was used to analyze and optimize the operating conditions, aimed at maximum chemical oxygen demand (COD) removal. The experiments were performed with a reaction volume of 2.6 L in batch mode. Based on these results, the optimal configuration was: agitation speed = 200 rpm, frequency of pulses = 1,000 Hz and spacing between electrodes = 1 mm, in 50 minutes of EC. Under these conditions it was obtained a COD removal of 81.23% (remainder value of 152 mg O2.L-1). In addition, it was found that the EC process is also effective for reduction of color, turbidity, total suspended solids, sulfate and sulfide. The concentration of chloride ions was not modified during the EC, presenting itself as a favorable aspect for the reuse of treated wastewater in the textile production process itself, which demands a high concentration of NaCl.

Effect of electrical stunning frequency on meat quality, plasma parameters, and protein solubility of broilers.

This study was designed to compare the effects of different stunning frequencies of pulsed direct current on meat quality of broilers. This was achieved by investigating plasma parameters, blood loss, carcass damage, meat water-holding capacity, meat color, meat shear value, muscle pH, and protein solubility. A total of 400 broilers was divided into 5 treatment groups and stunned with 500, 600, 700, 800, and 900 Hz at 15 V for 10 seconds. Blood samples were collected immediately after cutting the neck. Pectoralis major muscles were removed from the carcass after chilling and placed in ice. Breast muscle pH and meat color were determined at both 2 and 24 h postmortem. Drip loss, cooking loss, pressing loss, and cooked breast meat-shear values were determined at 24 h postmortem. Treatment at 500 and 900 Hz significantly increased (P < 0.05) blood plasma corticosterone and lactate concentrations compared with the 700 Hz group. The wing damage of carcasses was significantly serious in the 500, 800, and 900 Hz groups. The Pectoralis minor damage of carcesses in the 700 Hz group was significantly lower (P < 0.05) compared to the other stunning groups. The pH at 2 h postmortem in the 500 and 900 Hz groups was significantly lower (P < 0.05) than in other groups. However, the final pH and meat color were not affected by stunning frequency. In the 500 and 900 Hz groups, the protein solubility and shear force values were significantly lower (P < 0.05) and drip loss was significantly higher (P < 0.05) than in the 700 Hz group. This study indicates that the waveform of the pulsed direct current is acceptable for stunning broilers at a stunning frequency of 700 Hz.