Ultrasound to Enhance a Liquid–Liquid Reaction

Liquid–liquid mass transfer with ultrasound was investigated experimentally during the hydrolysis of n-amyl acetate. Power ultrasound is supposed to improve the yield and kinetics of such multiphase chemical reactions thanks to the mechanical effects of cavitation. Indeed, implosion of micro-bubbles at the vicinity of the liquid– liquid interface generates disruption of this surface, and enhances mixing in the liquid around the inclusion, thus improving mass transfer between the two phases. This effect has been demonstrated here on the hydrolysis of n-amyl acetate by sodium hydroxide, a rather slow reaction but influenced by mass transfer; the reaction is carried out in a glass jacketed reactor, 500 mL of volume, equipped with a Rushton turbine and a 20 kHz sonotrode dipping in the solution. The ester is initially pure in the organic dispersed phase, and sodium hydroxide has an initial concentration of 300 mol/m3; one of the products, pentanol partitions between the two phases and the sodium salt stays in the aqueous phase. The initial apparent reaction rate is measured from the record of the conductivity giving the concentration of alkali versus time. The reaction rate was always found to increase when ultrasound is superimposed to mechanical stirring (at 600 rpm), with a positive influence of input power (20 and 50 W). When varying initial concentration (300 and 600 mol/m3), temperature (36 and 45°C) and ultrasound emitter (sonotrode or cuphorn), the benefit of ultrasound over mechanical agitation was systematic. The only case of a weak influence of ultrasound was the sonication of a dense medium, containing 23% of organic phase and impeding the propagation of ultrasound

ICAR: endoscopic skull‐base surgery

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Stealth seeds: Bioproperty, biosafety, biopolitics

Transgenic seeds in both India (Bt cotton) and Brazil (glyphosate-resistant soybeans) spread widely and rapidly through farming communities outside the reach of biosafety or bioproperty institutions. Stealth transgenics are saved, cross-bred, repackaged, sold, exchanged and planted in an anarchic agrarian capitalism that defies surveillance and control of firms and states. The outcome is more pro-poor than alternative modes of diffusion, but undermines a growing consensus in the international development community on appropriate bio-safety and intellectual property institutions for biotechnology. Second, stealth procurement of biotechnology divides nominally pro-poor political coalitions, driven by a great ideational divide on uncertainties and risks of transgenics. The ability of seeds to move underground through stealth strategies of farmers undermines widely-assumed bio-safety-regime capability. Likewise, property in biotechnology appears less monopolistic and powerful, more relational and contingent. Stealth practices of farmers in pursuit of transgenics contrary to wishes of firms, states and many NGOs suggest a different model of the farmer than that often encountered in both developmentalist and anti-'GMO' discourse: more active, creative and autonomous, less hapless and supine. Resultant incapacity of social institutions to secure interests of firms and states in biotechnology renders more likely eventual development of controls from genetic engineering�-�the 'terminator technology' of political dramaturgy.

The genomics revolution and development studies: Science, poverty and politics

The genomics revolution in biology has enabled technologies with unprecedented potential; genetic engineering is changing the terrain of development studies. Societies have reacted with indifference or appreciation to genetically engineered pharmaceuticals, beginning with insulin; yet for food and agriculture, a globally contentious politics and unprecedented policy dilemmas have arisen. Transgenic organisms raise questions of property, ethics and safety unimaginable a generation ago: what can be owned and with what responsibility? Much turns on science: how one conceptualizes evidence, knowledge, uncertainty and risk. Both opponents and proponents of frontier applications in biotechnology have a poverty story to tell, but with divergent implications. The balance in this global debate has perceptibly shifted; a new developmentalist consensus concludes that the world's poor may benefit from genetic engineering: the question is 'under what conditions'? This essay introduces a collection of scholarly treatments that begin with the needs of the poor�-�for income, nutrition, environmental integrity�-�and evaluate theory and evidence for contributions from transgenic crops. The new consensus assumes much about biosafety, bioproperty and biopolitics that is contrary to ground realities�-�the actual capacity of firms and states to monitor and control biotechnology�-�but raises new questions at the frontiers of development studies.