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 microbial fuel cells and electrolysis cells (MXCs), anode-respiring bacteria (ARB) oxidize organic substrates to produce electrical current. In order to develop an electrical current, ARB must transfer electrons to a solid anode through extracellular electron transfer (EET). ARB use various EET mechanisms to transfer electrons to the anode, including direct contact through outer-membrane proteins, diffusion of soluble electron shuttles, and electron transport through solid components of the extracellular biofilm matrix. In this review, we perform a novel kinetic analysis of each EET mechanism by analyzing the results available in the literature. Our goal is to evaluate how well each EET mechanism can produce a high current density (> 10 A m(-2)) without a large anode potential loss (less than a few hundred millivolts), which are feasibility goals of MXCs. Direct contact of ARB to the anode cannot achieve high current densities due to the limited number of cells that can come in direct contact with the anode. Slow diffusive flux of electron shuttles at commonly observed concentrations limits current generation and results in high potential losses, as has been observed experimentally. Only electron transport through a solid conductive matrix can explain observations of high current densities and low anode potential losses. Thus, a study of the biological components that create a solid conductive matrix is of critical importance for understanding the function of ARB.

A kinetic perspective on extracellular electron transfer by anode-respiring bacteria.

This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs/aggregates (also called granules) without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL-1 can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR), packed bed reactor (PBR), fluidized bed reactor (FBR), airlift reactor (ALR), upflow anaerobic sludge blanket (UASB) reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes.

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Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

Interfacial tension was measured for hexane + water, heptane + water, octane + water, nonane + water, decane + water, undecane + water, and dodecane + water, using the emergent drop experimental technique with a numerical method based on a fourth degree spline interpolation of the drop profile. The experimental equipment used to generate the drop consists of a cell with a stainless steel body and two Pyrex windows. The inner cell was previously filled with water. A surgical needle (at the bottom of the cell) was used to introduce the organic phase into the cell (forming the emergent drop). Water was used to keep the temperature constant inside the cell (between 10 °C and 60 °C). The cell was illuminated from the back using a fiber optic lamp and a diffuser. A video camera (with a 60 mm microlens and an extension ring) was located at the front window. The emergent drop image was captured and sent to the video recording system. The cell and the optical components were placed on an optical table with vibration isolation legs. A new correlation was found to predict interfacial tension (γ) as a function of temperature (t) and the number of carbon atoms (n) with a deviation of less than 0.05% from experimental values.

Interfacial tension of alkane + water systems

Liquid antisolvent precipitation and stabilization of nanoparticles of poorly water soluble drugs in aqueous suspensions: Recent developments and future perspective

A successful industrial crystallization typically requires the development of a robust process in the laboratory. Knowledge of the solubility curve and the stability of the solution in the vicinity of the equilibrium point, as indicated by the metastable zone width, is essential to the successful development, optimization, and scale-up of a crystallization process. Use of the Lasentec Focused Beam Refiectance (FBRM) system, with aqueous potash alum solutions, to determine both the metastable zone width and solubility curve is demonstrated. The measured metastable zone width data are also used to estimate the nucleation kinetics of the system. Lasentec Particle Vision and Measurement (PVM) images are also employed to validate the results. The data collected using the FBRM system compare very well with published literature values for potash alum solubility and metastable zone width in aqueous solutions.

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Characterizing the metastable zone width and solubility curve using lasentec FBRM and PVM

Membrane aerated biofilm reactors (MABRs) represent a new technology for aerobic wastewater treatment. Oxygen diffuses through a gas permeable membrane into the biofilm where oxidation of pollutants, supplied on the biofilm side of the membrane, takes place. The potential of this system for various wastewater treatment applications is reviewed in the context of recent developments in the understanding of the fundamentals of such systems. The difference between MABRs and conventional biofilm reactors is highlighted by the concept of active layers within biofilms and the importance of active layer location. This review also discusses the choice of membrane in such reactors and the development of mathematical models that describe MABR performance. All published studies on the use of MABRs are discussed under pollutant species headings: organic carbonaceous pollutant biodegradation, volatile organic pollutant removal, and nitrification/denitrification processes.

Review of membrane aerated biofilm reactors

The use of laser light scattering technology, as applied by the Focused Beam Reflectance Measurement (FBRM) probe from Lasentec, for the in-line monitoring of particle size was investigated. In particular, the effects of probe position and orientation were studied for a dilute agitated aqueous particulate suspension of known particle size distribution in a number of vessels. In all cases, the normalised chord length distribution recorded with the FBRM system was consistent with the theoretically predicted distribution. However, the total number of counts measured was a function both of solids concentration and probe location. Optimum probe location is dependent on the ease with which the solid phase can be suspended with the available agitation system and on the associated dominant flow direction within the vessel.

In-line FBRM Monitoring of Particle Size in Dilute Agitated Suspensions

Glucose concentration control of a fed-batch mammalian cell bioprocess using a nonlinear model predictive controller

In this study, the application of Raman spectroscopy to the simultaneous quantitative determination of glucose, glutamine, lactate, ammonia, glutamate, total cell density (TCD), and viable cell density (VCD) in a CHO fed-batch process was demonstrated in situ in 3 L and 15 L bioreactors. Spectral preprocessing and partial least squares (PLS) regression were used to correlate spectral data with off-line reference data. Separate PLS calibration models were developed for each analyte at the 3 L laboratory bioreactor scale before assessing its transferability to the same bioprocess conducted at the 15 L pilot scale. PLS calibration models were successfully developed for all analytes bar VCD and transferred to the 15 L scale.

Brian Glennon

Papers

Characterizing the metastable zone width and solubility curve using lasentec FBRM and PVM

Review of membrane aerated biofilm reactors

In-line FBRM Monitoring of Particle Size in Dilute Agitated Suspensions

Glucose concentration control of a fed-batch mammalian cell bioprocess using a nonlinear model predictive controller

In situ Raman spectroscopy for simultaneous monitoring of multiple process parameters in mammalian cell culture bioreactors