There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Organic Photoredox Catalysis

介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

A flow-focusing geometry is integrated into a microfluidic device and used to study drop formation in liquid–liquid systems. A phase diagram illustrating the drop size as a function of flow rates and flow rate ratios of the two liquids includes one regime where drop size is comparable to orifice width and a second regime where drop size is dictated by the diameter of a thin “focused” thread, so drops much smaller than the orifice are formed. Both monodisperse and polydisperse emulsions can be produced.

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Formation of dispersions using “flow focusing” in microchannels

In this study, the environmental impacts of three ibuprofen production routes, namely, the BHC, the Bogdan, and the newly developed enzymatic synthetic routes (modified Bogdan process), are assessed and compared by the application of life cycle assessment (LCA). Based on the data obtained through literature and laboratory-based experiments, a pilot-scale production with a capacity of 500 g/day of ibuprofen was simulated to generate inventory data for the LCA study, using Aspen Plus V11. The well-established BHC process was chosen as the benchmark to quantify the operational and environmental benefits of the innovative enzymatic Bogdan flow synthetic process. The comparison highlights the benefit of adopting the modified Bogdan synthesis route via an enzymatic catalyst. Results show that a general reduction of environmental impact is achievable across the whole set of impact categories of the analysis, and the magnitude of such reduction depends on the efficiency of recycling in the production system. Considering a 50% efficiency of recycling, the modified Bogdan system achieves lower environmental impacts in some impact categories like Acidification, Ecotoxicity of freshwater, Human toxicity, Particulate matter, and Resource depletion (mineral, fossils, renewables) while having higher impacts on the rest of the impact categories. Yet, the new process proposed here scores better environmental performances in all of the impact categories when the enzyme recycling is close to 100%, which is promising for future technology development.

Life Cycle Assessment of an Enzymatic Ibuprofen Production Process with Automatic Recycling and Purification

Selective methanation of CO in a H2-rich stream performed over different supported-nickel catalysts showed that Ni–CeO2 and Ni–Cr2O3 were the most effective catalysts for complete removal of CO through selective methanation to decrease a concentration of CO from 1.6 vol % to ppm level (

Selective Methanation of Carbon Monoxide in Hydrogen-rich Reformate Using Microstructured Reactor

Mixing and emulsification processes in micromixers developed by the Institute of Microtechnology Maim (IMM) are investigated by means of computational fluid dynamics (CFD). For both miscible and immiscible fluids the CFD results are compared to experimental data obtained with transparent micromixer made from photosensitive glass. It is found that in the case of miscible liquids the accuracy of numerical predictions is limited by artifacts from numerical diffusion. However, streamline tracking techniques offer an alternative method for computing flow patterns in micrornixers. Corresponding flow patterns comply with photographic images of the mixing zone. Subsequently, the case of immiscible liquids is investigated using volume tracking techniques. The simulations, based on a 3D model for a planar interdigital micromixer, describe the time evolution of droplet formation. Data on droplet size and the decay wavelength of the liquid lamellae are in agreement with experimental results. Both the simulations and the experiments indicate that surface tension forces play the dominant role for droplet formation. Thus, the results suggest that even in the presence of wall boundaries and shear forces the Rayleigh-Plateau instability governs the dynamics.

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Mixing And Emulsification Processes InMicromixers

Cover Picture: Chemistry in Microstructured Reactors (Angew. Chem. Int. Ed. 4/2004)

A new micro mixer relying on the consequent utilization of the split-and-recombine (SAR) principle is presented. We show that the mixing can be characterized by a positive finite-time Lyapunov exponent although being highly regular and uniform. Furthermore, a spectral method based on the numerical solution of a pure diffusion equation is developed which allows a computation of concentration profiles and mixing residuals without artifacts from numerical diffusion. Eventually, we compare the performance of the SAR mixer to that of micro mixers relying on interdigital multilamination and hydrodynamic focusing and find it to be superior in terms of mixing efficiency, mixing time and pressure drop in the regime of small Reynolds numbers.

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Volker Hessel

Papers

Life Cycle Assessment of an Enzymatic Ibuprofen Production Process with Automatic Recycling and Purification

Selective Methanation of Carbon Monoxide in Hydrogen-rich Reformate Using Microstructured Reactor

Mixing And Emulsification Processes InMicromixers

Cover Picture: Chemistry in Microstructured Reactors (Angew. Chem. Int. Ed. 4/2004)

Optimized distributive µ-mixing by ‚chaotic' multilamination