An integrated microfluidic chip for generation and transfer of reactive species using gas plasma

Reactive species produced by atmospheric pressure plasma (APP) are useful in many applications including disinfection, pretreatment, catalysis, detection and chemical synthesis. Most highly reactive species produced by plasma, such as ·OH, 1O2 and , are short-lived; therefore, in-situ generation is essential to transfer plasma products to the liquid phase efficiently. A novel microfluidic device that generates a dielectric barrier discharge (DBD) plasma at the gas-liquid interface and disperses the reactive species generated using microbubbles of ca. 200 µm in diameter has been developed and tested. As the bubble size affects the mass transfer performance of the device, the effect of operating parameters and plasma discharge on generated bubbles size has been studied. The mass transfer performance of the device was evaluated by transferring the reactive species generated to an aqueous solution containing dye and measuring percentage degradation of the dye. Monodisperse microbubbles (polydispersity index between 2 - 7%) were generated under all examined conditions but for gas flow rate exceeding a critical value, a secondary break-up event occurred after bubble formation leading to multiple monodisperse bubble populations. The generated microbubble size increased by up to ~ 8% when the device was operated with the gas plasma in the dispersed phase compared to the case without the plasma due to thermal expansion of the feed gas. At the optimal operating conditions, initial dye concentration was reduced by ~60% in a single pass with a residence time of 5-10 s. This microfluidic chip has the potential to play a significant role in lab-on-a-chip devices where highly reactive species are essential for the process. </p

Supplementary Information Files for 'An integrated microfluidic chip for generation and transfer of reactive species using gas plasma'

Supplementary Information Files for 'An integrated microfluidic chip for generation and transfer of reactive species using gas plasma'Abstract:Reactive species produced by atmospheric pressure plasma (APP) are useful in many applications including disinfection, pretreatment, catalysis, detection and chemical synthesis. Most highly reactive species produced by plasma, such as ·OH, 1O2 and , are short-lived; therefore, in-situ generation is essential to transfer plasma products to the liquid phase efficiently. A novel microfluidic device that generates a dielectric barrier discharge (DBD) plasma at the gas-liquid interface and disperses the reactive species generated using microbubbles of ca. 200 µm in diameter has been developed and tested. As the bubble size affects the mass transfer performance of the device, the effect of operating parameters and plasma discharge on generated bubbles size has been studied. The mass transfer performance of the device was evaluated by transferring the reactive species generated to an aqueous solution containing dye and measuring percentage degradation of the dye. Monodisperse microbubbles (polydispersity index between 2 - 7%) were generated under all examined conditions but for gas flow rate exceeding a critical value, a secondary break-up event occurred after bubble formation leading to multiple monodisperse bubble populations. The generated microbubble size increased by up to ~ 8% when the device was operated with the gas plasma in the dispersed phase compared to the case without the plasma due to thermal expansion of the feed gas. At the optimal operating conditions, initial dye concentration was reduced by ~60% in a single pass with a residence time of 5-10 s. This microfluidic chip has the potential to play a significant role in lab-on-a-chip devices where highly reactive species are essential for the process.</div

The Role of Drug Expectancy in the Control of Human Drug Seeking

Human drug seeking may be goal directed in the sense that it is mediated by a mental representation of the drug or habitual in the sense that it is elicited by drug-paired cues directly. To test these 2 accounts, the authors assessed whether a drug-paired stimulus (S+) would transfer control to an independently trained drug-seeking response. Smokers were trained on an instrumental discrimination that established a tobacco S+ in Experiment 1 and a tobacco and a money S+ in Experiment 2 that elicited an expectancy of their respective outcomes. Participants then learned 2 new instrumental responses, 1 for each outcome, in the absence of these stimuli. Finally, in the transfer test, each S+ was found to augment performance of the new instrumental response that was trained with the same outcome. This outcome-specific transfer effect indicates that drug-paired stimuli controlled human drug seeking via a representation or expectation of the drug rather than through a direct stimulus-response association

Plasma-assisted pre-treatment of lignocellulosic biomass for anaerobic digestion

The conversion of industrial crops to energy has received significant attention recently as a means to reduce carbon emissions and meeting the renewable energy targets. Samples of whole crop maize (Zea mays L.) were pre-treated in tap water using a novel microbubble-enhanced dielectric barrier discharge (DBD) plasma reactor that generates highly reactive species in situ and distribute them using microbubbles. The pre-treated maize was then used as feedstock in batch and continuously-fed mesophilic continuously-stirred anaerobic digesters (AD). Half of the pre-treated samples were washed in deionized water prior to feeding to assess the effect of possible inhibitory by-products generated during pre-treatment. In batch AD experiments, DBD-plasma pre-treated and washed maize produced 18% greater biogas production in comparison to untreated raw samples, and unwashed samples produced 29% lower biogas than the untreated samples. These results suggest the production of inhibitors to the AD process, but biogas production can be enhanced by removing these inhibiting compounds. Continuously-fed AD reactors exhibited no noticeable change in biogas output between raw and plasma-treated maize. For AD reactors operating in batch, or with a relatively long residence time and fed with high lignocellulose feedstocks, plasma-microbubble pre-treatment could enhance biogas output and process efficiency