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

The Claisen rearrangement is an ideal candidate for mechanistic and transition-state analysis. Recently, physical-chemistry investigations, in particular relying on quantum mechanics and modern fs-pulse (‘short-time') laser spectroscopy, have given totally new insights here. At the same time, flow chemistry has emerged, offering considerable processing advances over batch processing. It is also known to be much powerful with inline flow sensing techniques. Yet, both key innovations have not been bridged so far and thus there is an eminent knowledge gap in mechanistic analysis of reactions. This two-review compilation is a first step to close this gap. Part 1 focuses on the insight which quantum-mechanical calculations can add to the existing knowledge based on heuristic, handy interpretation of reaction experiments in the light of electrodensity distributions. Quantum-mechanical calculation can provide geometric key data and short-time laser spectroscopy can verify this and deepen it in the sense of a comprehensive vibration analysis. In this way, prior structural assumptions can be confirmed or turned to be falsified and there is potential to resolve the uncertainty.

Volker Hessel

Papers

The Claisen Rearrangement. Part 1. Mechanisms and Transition States, Revisited with Quantum Mechanical Calculations and Ultrashort Pulse Spectroscopy