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We report the suppression of nucleation in the nonphotochemical laser-induced nucleation of supersaturated aqueous potassium chloride solutions when the system pressure is above ambient pressure. The crystal yield at 51.7 bar is reduced to 5% of its value at 1 bar, and the crystal number dependence on pressure fits well to a semiempirical model based on the impurity-heating mechanism and the adiabatic compression of an ideal gas nanobubble. Our results complement recent findings by Barber and Alexander [] using high-speed imaging of bubbles preceding the observation of cesium chloride crystals. Together, these two studies provide compelling evidence for the impurity-heating mechanism. 

Combined analysis of optical emission spectroscopy and infrared thermography revealing how liquid properties affect plasma ignition in a dielectric barrier discharge microfluidic system where methane-containing gas interacts with organic liquids. 

Reforming of methane (CH4) is a process to produce syngas (CO/H2) and other value-added chemicals including oxygenates such as methanol (CH3OH). Atmospheric pressure plasmas have the potential to be more energy efficient than traditional reforming methods as value-added chemicals can be synthesized directly in the plasma without requiring an additional step. In this paper, we discuss the results from a computational investigation of the formation of oxygenates by CH4 oxidation in the presence of Ar, including CH3OH and CH2O, in a nanosecond pulsed dielectric barrier discharge. The plasma is formed in a microfluidic channel whose small dimensions are ideal for plasma formation at atmospheric pressure. The production and consumption mechanisms of dominant radicals and long-lived species are discussed in detail for the base case conditions of Ar/CH4/O2 = 50/25/25. CH3OH is produced primarily by CH3O reacting with CH3O and CH3O2 reacting with OH, while CH2O formation relies on reactions involving CH3O and CH3. The most abundant oxygenate formed is CO (produced by H abstraction from CHO). However, the greenhouse gas CO2 is also formed as a by-product. The effects of gas mixture are examined to maximize the CH3OH and CH2O densities while decreasing the CO2 density. Increasing the Ar percentage from 0% to 95% decreased the CH3OH and CH2O densities. At low Ar percentages, this is due to an increase in consumption of CH3OH and CH2O, while at high Ar percentages (>40% Ar), the production of CH3OH and CH2O is decreased. However, both CO and CO2 reached peak densities at 70%–90% Ar. Changing the CH4/O2 ratio while keeping 50% Ar in the discharge led to increased CH3OH and CH2O production, reaching peak densities at 35%–40% CH4. The CO and CO2 densities decreased beyond 20% CH4, indicating that a CH4 rich discharge is ideal for forming the desired oxygenates. 

The conversion of methane, CH4, into higher value chemicals using low temperature plasmas is challenged by both improving efficiency and selectivity. One path towards selectivity is capturing plasma produced methyl radicals, CH3, in a solvent for aqueous processing. Due to the rapid reactions of methyl radicals in the gas phase, the transport distance from production of the CH3 to its solvation should be short, which then motivates the use of microplasmas. The generation of CH3 in Ar/CH4/H2O plasmas produced in nanosecond pulsed dielectric barrier discharge microplasmas is discussed using results from a computational investigation. The microplasma is sustained in the channel of a microfluidic chip in which the solvent flows along one wall or in droplets. CH3 is primarily produced by electron-impact of and dissociative excitation transfer to CH4, as well as CH2 reacting with CH4. CH3 is rapidly consumed to form C2H6 which, in spite of being subject to these same dissociative processes, accumulates over time, as do other stable products including C3H8 and CH¬3OH. The gas mixture and electrical properties were varied to assess their effects on CH3 production. CH3 production is largest with 5% CH4 in the Ar/CH4/H2O mixture due to an optimal balance of electron-impact dissociation, which increases with CH4 percentage, and dissociative excitation transfer and CH2 reacting with CH4, which decrease with CH4 percentage. Design parameters of the microchannels were also investigated. Increasing the permittivity of the dielectrics in contact with the plasma increased the ionization wave intensity which increased CH3 production. Increased energy deposition per pulse generally increased CH3 production as does lengthening pulse length up to a certain point. The arrangement of the solvent flow in the microchannel can also affect the CH3 density and fluence to the solvent. The fluence of CH3 to the liquid solvent is increased if the liquid is immersed in the plasma as a droplet or is a layer on the wall where the ionization wave terminates. The solvation dynamics of CH3 with varying numbers of droplets was also examined. The maximum density of solvated methyl radicals CH3aq occurs with a large number of droplets in the plasma. However, the solvated CH3aq density can rapidly decrease due to desolvation, emphasizing the need to quickly react the solvated species in the solvent. 

Traditionally catalysis research and development has been limited to large purpose-built labs, requiring years of planning and implementation before the first molecules were even examined. However, recent developments in microfluidics, robotics, system miniaturization and machine intelligence allow the decoupling of research from multi-million dollar purpose-built facilities. Additionally this scaling-down of research has significant benefits for the environment, development timelines and researcher workload. In this publication we demonstrate the construction of a microfluidic catalysis research platform contained within a standard hard-sided case measuring just 0.73 m 2 , consuming under 100 W of power, and generating 66.7 μL of chemical waste per min. The system integrates a purpose-built microreactor with hot-swappable chuck, vacuum enclosure, manifolds, pumps, robotic autosampling, open-source controls and thermographic performance analysis. The system was used to investigate nine chemically different activators for a zirconocene-catalyzed α-olefin polymerization through efficient experimentation and automated transfer learning ML-based data interpretation. The contributions of different chemical structures to catalytic productivity were analyzed. Conclusions made include those regarding co-catalyst chemistry and probable operating conditions. This work demonstrates that a compact flow-based microfluidic platform can screen exothermic catalytic reactions and interpret the results using machine intelligence. 

Systematic investigations of vertebrate faunas from the islands of Melanesia are revealing high levels of endemism, dynamic biogeographic histories, and in some cases surprisingly long evolutionary histories of insularity. The bent-toed geckos in the Cyrtodactylus sermowaiensis Group mainly occur in northern New Guinea and nearby islands, however a further isolated population occurs on Manus Island in the Admiralty Archipelago approximately 300 km to the north of New Guinea. Here we first present a review of the genetic diversity, morphological variation and distribution of Cyrtodactylus sermowaiensis from northern New Guinea. Genetic structure and distributional records within Cyrtodactylus sermowaiensis broadly overlap with underlying Terranes in northern New Guinea, suggesting divergence on former islands that have been obscured by the infill and uplift of sedimentary basins since the late Pleistocene. Based on a combination of genetic and morphological differentiation we then describe the population from Manus Island as a new species, Cyrtodactylus crustulus sp. nov. This new species emphasises the high biological endemism and conservation significance of the Admiralty Islands, and especially Manus Island.