Knowledge‐Based Conceptual Synthesis of Industrial‐Scale Downstream Processes for Biochemical Products

A generic, knowledge‐based guideline assisting downstream process synthesis for biochemical products is presented. It offers process designers a structured process design methodology supporting them in capturing potentially relevant information, which might be beyond their expertise. The guideline is based on heuristic knowledge which was collected, structured in a generic way, and clearly represented. The generation of alternative downstream routes as starting points for experiments, simulation, and cost calculation is hereby accelerated. The application of the guideline is demonstrated on the example of penicillin V downstream processing from fermentation broth.     

In the Nick of Time: Males of the Parasitoid Wasp <Emphasis Type="Italic">Pimpla disparis</Emphasis> Respond to Semiochemicals from Emerging Mates

Males of the parasitoid wasp Pimpla disparis Viereck (Hymenoptera: Ichneumonidae) aggregate on parasitized gypsy moth, Lymantria dispar, host pupae when the emergence of a prospective mate is imminent or under way. We tested the hypotheses that the developing parasitoid (“DePa”) inside the host pupal case produces a pheromone that attracts and arrests mate-seeking males, and that the pheromone is most effective during the emergence of the parasitoid from the host. Results obtained in two-choice laboratory experiments, with 4–7-d-old virgin males, indicate that (1) DePa-derived semiochemicals arrest males, (2) the opening of a host pupal case strongly arrests males, and (3) the arrestment cue emanates from oral fluid secreted by both female and male parasitoids while they chew their way out of a host pupal case. This phenomenon implies that emerging females, which are haplodiploid and can reproduce without mating, do not engage in active pheromone signaling to attract males, and that mate-seeking males co-opt chemicals involved in eclosion as a mate-finding cue, taking a 50% chance that the prospective mate is a female.     

Random and block copolymers based on 4-methyl-1-pentene and 1-pentene

The zirconium acetamidinate catalyst {Cp*Zr(Me)₂[N(Et)C(Me)N(tBu)]} (Cp* = ?⁵-C₅Me₅) was used to synthesize both random and block copolymers based on 4-methyl-1-pentene (4M1P) and 1-pentene. The polymers have been characterized by NMR spectroscopy, SEC, DSC, high temperature HPLC and CRYSTAF. Unexpectedly, the yields and molecular weights decreased with increasing amounts of 1-pentene. The reason for this behavior is that 1-pentene occasionally undergoes 2,1-misinsertions trapping the catalyst in a dormant state. These 2,1-misinsertions do not seem to occur with the bulky 4M1P (branched α-olefin). Adding a small amount of ethylene reactivates the catalyst. Unlike most semi-crystalline polymers, the density of the crystalline phase of isotactic P4M1P can be lower than of the amorphous phase, when crystallized under very high pressures. To characterize this peculiar behavior of 4M1P-based polymers, various samples have been subjected to Pressure-Volume-Temperature (PVT) measurements. While the P4M1P homopolymers and block copolymers show the expected decrease in specific volume upon crystallization, the 4M1P-rich random copolymers proved not to vary in specific volume under the same conditions.     

Cast polyurethane elastomers with improved dynamic fatigue resistance

Cast polyurethane (PU) elastomers have been widely used in dynamic applications, such as rollers and wheels, where a low heat buildup, high-loading resistance, and good cut-growth resistance are desired. Because of their different molecular structure, cast PU elastomers do not perform in the same way in highly demanding dynamic applications. Small variations in the viscoelastic properties can result in significant differences in the longevity of the wheels and rollers that are subjected to a large number of cyclic compressive deformations. Therefore, it is of great interest to understand dynamic performance of urethane elastomers based on various backbones. Dynamic mechanical analysis (DMA) is commonly used to differentiate the dynamic performance of elastomers, but it only provides characterization of the dynamic behavior of a given elastomer at small deformation in the linear viscoelastic regime, where information such as the heat buildup and load-bearing capability of elastomers cannot be obtained. As such, we developed a stress-controlled flexometer on the basis of the ISO4666/4 method that enabled measurement of the heat buildup and load-bearing capabilities of urethane elastomers in a large dynamic deformation environment. Moreover, a dynamometer was constructed to evaluate wheels based on different urethane elastomers under load at various speeds; this allowed close simulation of the urethane elastomers in a real application environment. In this article, the viscoelastic properties of cast urethane elastomers based on different backbones were studied by DMA. The heat buildup and load-bearing capabilities of the elastomers were investigated via the stress-controlled flexometer, and the performance of the wheels based on various prepolymer systems were evaluated with the dynamometer. Correlations between the material viscoelastic behavior and the heat buildup were established. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Near-field optical microscopy of femtosecond-laser-reshaped silver nanoparticles in dielectric matrix

ABSTRACT: : Samples containing single silver nanoparticles have been irradiated by intense femtosecond laser pulses to gain a persistent transformation of their shape to ellipsoidal forms. Irradiated and non-irradiated regions of these samples have been analyzed by microscope spectrometry as well as near-field scanning optical microscopy (NSOM) with several wavelengths and different linear polarizations. The results show the outstanding capability of NSOM technique to detect the individual shape of transformed metallic nanoparticles and to analyze their orientation and aspect ratio.     

(Z,Z)-4,7-tridecadien-(S)-2-yl acetate: sex pheromone of Douglas-fir cone gall midge,Contarinia oregonensis

Our objectives were to identify and field test the sex pheromone of female Douglas-fir cone gall midge, Contarinia oregonensis (Diptera: Cecidomyiidae). Coupled gas chromatographic–electroantennographic detection (GC-EAD) analyses of pheromone extract revealed a single compound (A) that elicited responses from male antennae. Hydrogenation of pheromone extract, followed by renewed GC-EAD analysis, revealed a new EAD-active compound with chromatographic characteristics identical to those of tridecan-2-yl acetate on five fused silica columns (DB-5, DB-210, DB-23, SP-1000, and Cyclodex-B). Syntheses, chromatography, and retention index calculations of all possible tridecen-2-yl acetates suggested that the candidate pheromone A was a tridecadien-2-yl acetate with nonconjugated double bonds. Synthetic candidate pheromone component (Z,Z)-4,7-tridecadien-2-yl acetate (Z4Z7) cochromatographed with A on all analytical columns and elicited comparable antennal activity. In GC-EAD analyses that separated the enantiomers (Z,Z)-4,7-tridecadien-(S)-2-yl acetate (2S-Z4Z7) and (Z,Z)-4,7-tridecadien-(R)-2-yl acetate (2R-Z4Z7) with baseline resolution, only 2S-Z4Z7 as a component in a racemic standard or in pheromone extract elicited antennal responses. In Douglas-fir seed orchards, sticky traps baited with 2S-Z4Z7 captured male C. oregonensis, whereas 2R-Z4Z7 was behaviorally benign. Comparable catches of males in traps baited with racemic Z4Z7 (50 g) or virgin female C. oregonensis suggested that synthetic pheromone baits could be developed for monitoring C. oregonensis populations in commercial Douglas-fir seed orchards.     

Mesoscale simulation of block copolymers in aqueous solution: parameterisation, micelle growth kinetics and the effect of temperature and concentration morphology

In this work, we utilise ‘MesoDyn’ [J Chem Phys 99 (1993) 9202; 106 (1997) 4260] density functional simulations to study the effect of temperature and concentration on the micellar morphology of polymeric surfactants. Parameterisation strategies based upon atomistic models and experimental data are discussed. Taking the temperature dependence of interaction energy into account, the change in morphology of Pluronic (PEO-PPO-PEO) block copolymer structure with temperature is well reproduced. As a function of concentration, the diameter of spherical micelles is found to increase in line with previous cryo-TEM observations [Phys Chem Chem Phys 1 (1999) 3331]. Simulations of high concentration PEO-PBO diblock systems show ordering similar to the face-centered cubic structures found experimentally [J Polym Sci B 33 (1995) 1085; Macromolecules 30 (1997) 5721; Polymer 39 (1998) 4891; Phys Chem Chem Phys 1 (1999) 2773].     

Fungal aerobic reductive dechlorination of ethyl 2-chloroacetoacetate by Saccharomyces cerevisiae: mechanism of a novel type of microbial dehalogenation

Saccharomyces cerevisiae reduces the beta-keto ester ethyl 2-chloroacetoacetate to the respective chiral cis- and trans-beta-hydroxy esters. In the course of chiral reduction, competing dehalogenation of the xenobiotic substrate to ethyl acetoacetate occurs, in a reaction mediated by cytosolic glutathione (GSH). Mechanistically, the dechlorination is a novel type of glutathione-dependent dehalogenation catalysed by an as yet unidentified glutathione-dependent dehalogenase. The first step consists of a nucleophilic replacement of the chloride substituent by glutathione. In the subsequent enzyme-catalysed step, a second glutathione molecule liberates the dehalogenation product by thiolytic attack at the thioether bridge, resulting in a net transfer of two electrons to the substrate and in the formation of glutathione disulfide (GSSG). Being effective under aerobic conditions and catalysed by a fungus, this reductive dechlorination of an aliphatic substrate is an outstanding example of a novel, glutathione-mediated microbial dehalogenation.     

Synthesis and Characterization of Segmented Block Copolymers Based on Hydroxyl‐Terminated Liquid Natural Rubber and α,ω‐Diisocyanato Telechelics

Summary: Segmented block copolymers, consisting of non‐polar soft segments from hydroxyl‐terminated liquid natural rubber (HTNR) and polar hard segments from α,ω‐diisocyanato telechelics obtained by “criss‐cross”‐cycloaddition, have been synthesized. The block copolymer formation took place under relatively mild reaction conditions at 80 °C in dichloroethane in the presence of dibutyltin dilaurate as a catalyst. The resulting block copolymers were characterized by spectroscopic techniques (¹H NMR, FTIR, UV‐vis spectroscopy) as well as GPC for molar mass determination. The block copolymers were compression molded in a hot stage press, and the resulting samples were characterized by DSC and stress‐strain measurement. The solubility and phase morphology of the materials have also been studied.

Segmented block copolymer from HTNR and α,ω‐diisocyanato telechelics     

Acquired Smell? Mature Females of the Common Green Bottle Fly Shift Semiochemical Preferences from Feces Feeding Sites to Carrion Oviposition Sites

We investigated foraging decisions by adult females of the common green bottle fly, Lucilia sericata, in accordance with their physiological state. When we gave female flies a choice between visually occluded, fresh canine feces (feeding site) and a CO₂-euthanized rat (carrion oviposition site), 3-d-old “protein-starved” females responded equally well to feces and carrion, whereas protein-fed gravid females with mature oocytes responded only to carrion, indicating resource preferences based on a fly’s physiological state. Dimethyl trisulfide (DMTS) is known to attract gravid L. sericata females to carrion. Therefore, we analyzed headspace from canine feces by gas chromatographic-electroantennographic detection (GC-EAD) and GC/mass spectrometry. In bioassays, of the 17 fecal odorants that elicited GC-EAD responses from fly antennae, a blend of indole and one or more of the alcohols phenol, m-/p-cresol and 1-octen-3-ol proved as attractive to flies as canine feces. Unlike young females, gravid females need to locate carrion for oviposition and distinguish between fresh and aging carrion, the latter possibly detrimental to offspring. Gravid female L. sericata accomplish this task, in part, by responding to trace amounts of DMTS emanating from fresh carrion and by discriminating against carrion as soon it begins to produce appreciable amounts of indole, which is also the second-most abundant semiochemical in fresh canine feces, and apparently serves as an indicator of food rather than oviposition resources. Our results emphasize the importance of studying foraging choices by flies in accordance with their physiological stage.