Generalizing the safety factor approach

Safety factors (uncertainty factors) are used to avoid failure in a wide variety of practices and disciplines, in particular engineering design and toxicology. Although these two areas have similar problems in their use of safety factors, there are no signs of previous communication between the two disciplines.The present contribution aims at initiating such communications by pointing out parallel practices and joint issues between the two disciplines. These include the distinction between probabilistic variability and epistemic uncertainty, the importance of distribution tails, and the problem of countervailing risks. In conclusion, it is proposed that future research in this area should be interdisciplinary and make use of experiences from the various areas in which safety factors are used.     

Local tissue reactions to subplatysmal implants of cold polymerizing silastic as bladder prostheses in the animal experiment

In animal experiments silicone rubber bodies of various volumes and weights were implanted under the platysma. The grafts were completely tolerated by 6 rabbits and partially by a minipig, but not at all by 4 dogs. The primary reason for the failures were chronic inflammation by motion of the graft, heaviness of the plastic material, and stromal weakness.     

Gesetzmäßigkeiten im Verhalten duroplastischer Kunststoffe auf der Basis von Phenolharz

Procedure of behavior of phenolic moulded material. Investigations of composites (multiphase systems) from resin/wood flour/stone powder show that the properties of these phenolic plastics are connected with composition of material and technical climate. The knowledge of these connections allows an economic selection of parts produced by moulded material for various requirements.     

Influence of anthraquinones on the formation of urinary calculi in experimental animals (author''s transl)

A method is presented for the quantitation of urinary and CSF protein. In the presence of 0.10 N NaOH the peptide bonds of the protein remove and bind copper from an ion exchange resin. The resulting copper-protein complex is separated from low molecular weight substances by gel filtration and the copper in the eluted complex is determined colorimetrically with diethyldithiocarbamic acid. The method requires only 100mul of sample, has biuret specificity and uses a single prepacked column. The limit of sensitivity is 2 mg of protein per deciliter.     

Mathematical Programming Solution of a Hoist Scheduling Program

This paper describes a mixed integer programming model of a process during which electronic circuit boards are chemically treated in a sequence of tanks. The boards must remain in these tanks for periods of time lying within specified bounds. A hoist mechanism is to be programmed to place boards into tanks, remove boards from tanks, and transport boards between tanks, so as to maximize the throughput of the system. Computational experience and a detailed example are given.     

Predictive equations in gas adsorption kinetics

The experimental method of determining the operative parameters of adsorptive capacity and rate in the gas adsorption kinetics of packed bed sorbents relies upon the linear relationship between gas breakthrough time and sorbent weight. The slope and intercept of the straight line, resulting from such a plot, yields values for the gas saturation capacity and adsorption rate constant of the adsorbent. This relationship is shown in the modified Wheeler adsorption equation, originally derived from a continuity equation of mass balance between the gas entering an adsorbent bed and the sum of the gas adsorbed by plus that penetrating through the bed. We have found that for wellpacked adsorbent beds, the Dubinin-Polanyi equations for predicting adsorption space at equilibrium, based upon prior characterization of an adsorbent with a reference gas, could also be applied to gas flow conditions, and the kinetic capacity of the adsorbent predicted within close limits. Although no theoretical relationship exists for prediction of the adsorption rate constant, recent gas tests at high linear flow velocities have shown experimental evidence of the mass transfer limiting value for the rate constant. The functionalities of the kinetic saturation capacity and the mass transfer limited value for the adsorption rate constant have been incorporated into the modified Wheeler adsorption equation to provide an expanded equation permitting prediction by calculation of the breakthrough time of a gas through a well-packed bed of adsorbent granules.     

The Need for Heroes

In a play about Galileo, Bertold Brecht has one of his characters comment bitterly after Galileo's recantation that "unhappy is a land that breeds no heroes." The reply by Galileo is "unhappy is a land that needs heroes."     

Airborne chemistry coupled to Raman spectroscopy

In this paper, the use of airborne chemistry (acoustically levitated drops) in combination with Raman spectroscopy is explored. We report herein the first Raman studies of crystallization processes in levitated drops and the first demonstration of surface-enhanced Raman scattering (SERS) detection in this medium. Crystallization studies on the model compounds benzamide and indomethacin resulted in the formation of two crystal modifications for each compound, suggesting that this methodology may be useful for investigation of polymorphs. SERS detection resulted in a signal enhancement of 27 000 for benzoic acid and 11 000 for rhodamine 6-G. The preliminary results presented here clearly indicate that several important applications of the combination between Raman spectroscopy and acoustic drop levitation can be expected in the future.     

Direct plasma sample injection in multiple-component LC-MS-MS assays for high-throughput pharmacokinetic screening

The simultaneous dosing of numerous compounds followed by multiple-component analysis using LC-MS-MS (the N-in-1 approach) has significantly improved the throughput of the drug-screening process. However, plasma samples still need to be extracted before LC-MS-MS analysis, which frequently limits the throughput of the assay. In this work, a high-throughput on-line extraction technique has been developed for multiple-component LC-MS-MS assays using a high-flow column-switching technique. In N-in-1 LC-MS-MS assays, high sensitivity is required since the dose level is generally reduced to minimize drug-drug interactions. In addition, good chromatographic separation is essential to minimize interference and suppression effects. The direct plasma sample injection method developed in this work has successfully met the two requirements for multiple-component LC-MS-MS assays in high-throughput pharmacokinetic screening. Plasma samples containing a large number of potential drug candidates were directly injected onto an extraction column operated under a flow rate sufficiently high to exhibit a turbulent-flow profile. The extracted analytes were then eluted onto an analytical column via column switching for LC-MS-MS analysis. The use of turbulent flow resulted in a faster and more rugged extraction with reduced carryover compared with results obtained under laminar-flow conditions. Meanwhile, the use of a column-switching method maintained the chromatographic resolving power and high sensitivity of the LC-MS-MS assay. Separation efficiency, dynamic range, accuracy, and precision comparable with those of solid-phase extraction have been achieved with the turbulent-flow column-switching technique. As a result, this technique has been successfully and routinely used for high-throughput pharmacokinetic screening.