Vapor recognition with small arrays of polymer-coated microsensors. A comprehensive analysis.

A comprehensive analysis of vapor recognition as a function of the number of sensors in a vapor-sensor array is presented. Responses to 16 organic vapors collected from six polymer-coated surface acoustic wave (SAW) sensors were used in Monte Carlo simulations coupled with pattern recognition analyses to derive statistical estimates of vapor recognition rates as a function of the number of sensors in the array (< or = 6), the polymer sensor coatings employed, and the number and concentration of vapors being analyzed. Results indicate that as few as two sensors can recognize individual vapors from a set of 16 possibilities with < 6% average recognition error, as long as the vapor concentrations are > 5 x LOD for the array. At lower concentrations, a minimum of three sensors is required, but arrays of 3-6 sensors provide comparable results. Analyses also revealed that individual-vapor recognition hinges more on the similarity of the vapor response patterns than on the total number of possible vapors considered. Vapor mixtures were also analyzed for specific 2-, 3-, 4-, 5-, and 6-vapor subsets where all possible combinations of vapors within each subset were considered simultaneously. Excellent recognition rates were obtainable for mixtures of up to four vapors using the same number of sensors as vapors in the subset. Lower recognition rates were generally observed for mixtures that included structurally homologous vapors. Acceptable recognition rates could not be obtained for the 5- and 6-vapor subsets examined, due, apparently, to the large number of vapor combinations considered (i.e., 31 and 63, respectively). Importantly, increasing the number of sensors in the array did not improve performance significantly for any of the mixture analyses, suggesting that for SAW sensors and other sensors whose responses rely on equilibrium vapor-polymer partitioning, large arrays are not necessary for accurate vapor recognition and quantification.     

Action of Tocopherol-Type Compounds in Directing Reactions Forming Flavor Compounds in Autoxidizing Fish Oils

Menhaden and cod liver oils without additives or containing either α-tocopherol (670 ppm) or Trolox C (1000 ppm) with or without copper (II) cations (20 ppm) were oxidized under air at 65‡C, and their headspace volatiles were quantitatively measured by capillary gas chromatography. Samples prepared without additives contained very little l,5-octadien-3-one. Fish oils with Trolox C had distinct metallic, vinyl-ketone aromas, while those with a-tocopherol exhibited extremely fishy, cod liver-like aromas. High levels of 1,5-octadien-3-one and 1,5-octadien-3-ol and moderate levels of 2,4,7-decatrienals were found in samples with Trolox C, while moderate levels of the 8-carbon compounds and high levels of the 2,4,7-decatrienals were present in the α-tocopherol samples. Copper (II) greatly accelerated the overall rate of oxidation in samples, and in the presence of Trolox C it induced the formation of very high levels of 1,5-octadien-3-ol.     

Amphiphilic peroxynitrite decomposition catalysts in liposomal assemblies

BACKGROUND: Peroxynitrite (ONOO-), a toxic biological oxidant, has been implicated in many pathophysiological conditions. The water-soluble porphyrins 5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphinato iron(III) (FeTMPyP) and manganese(III) (MnTMPyP) have recently emerged as potential drugs for ONOO- detoxification, and FeTMPyP has demonstrated activity in models of ONOO- related disease states. We set out to develop amphiphilic analogs of FeTMPyP and MnTMPyP suitable for liposomal delivery in sterically stabilized liposomes (SLs). RESULTS: Three amphiphilic iron porphyrins (termed 1a-c.) and three manganese porphyrins (termed 2a-c.) bound to liposomes and catalyzed the decomposition of ONOO-. The polyethylene-glycol-linked metalloporphyrins 1b. and 2b. proved the most effective of these catalysts, rapidly decomposing ONOO- with second-order rate constants (kcat) of 2.9 x 10(5) M-1 s-1 and 5.0 x 10(5) M-1 s-1, respectively, in dimyristoylphosphatidylcholine liposomes. Catalysts 1b. and 2b. also bound to SLs, and these metalloporphyrin-SL constructs efficiently catalyzed ONOO- decomposition (kcat approximately 2 x 10(5) M-1 s-1). The analogous metalloporphyrins 1a. and 2a., which are not separated from the vesicle membrane surface by polyethylene glycol linkers, were significantly less effective (kcat approximately 3.5 x 10(4) M-1 s-1). CONCLUSIONS: For these amphiphilic analogs of FeTMPyP and MnTMPyP, the polarity of the environment of the metalloporphyrin headgroup is intimately related to the efficiency of the catalyst; a polar aqueous environment is essential for effective catalysis of ONOO- decomposition. Thus, catalysts 1b. and 2b. react rapidly with ONOO- and are potential therapeutic agents that, unlike their water-soluble TMPyP analogs, could be administered as liposomal formulations in SLs. These SL-bound amphiphilic metalloporphyrins may prove to be highly effective in the exploration and treatment of ONOO- related disease states.     

Business processes—attempts to find a definition

Definitions of business process given in much of the literature on Business Process Management are limited in depth and their related models of business processes are correspondingly constrained. After giving a brief history of the progress of business process modeling techniques from production systems to the office environment, this paper proposes that most definitions are based on machine metaphor type explorations of a process. While these techniques are often rich and illuminating it is suggested that they are too limited to express the true nature of business processes that need to develop and adapt to today's challenging environment.     

Developmental differences in the effects of repeated interviews and interviewer bias on young children's event memory and false reports.

The present study investigated developmental differences in the effects of repeated interviews and interviewer bias on children's memory and suggestibility. Three- and 5-year-olds were singly or repeatedly interviewed about a play event by a highly biased or control interviewer. Children interviewed once by the biased interviewer after a long delay made the most errors. Children interviewed repeatedly, regardless of interviewer bias, were more accurate and less likely to falsely claim that they played with a man. In free recall, among children questioned once after a long delay by the biased interviewer, 5-year-olds were more likely than were 3-year-olds to claim falsely that they played with a man. However, in response to direct questions, 3-year-olds were more easily manipulated into implying that they played with him. Findings suggest that interviewer bias is particularly problematic when children's memory has weakened. In contrast, repeated interviews that occur a short time after a to-be-remembered event do not necessarily increase children's errors, even when interviews include misleading questions and interviewer bias. Implications for developmental differences in memory and suggestibility are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)