Online monitoring of a bioprocess based on a multi‐analyser system and multivariate statistical process modelling

Multivariate statistical process control (MSPC) was for the first time applied to analyse data from a bioprocess on‐line multi‐analyser system consisting of an electronic nose (EN), a near‐infrared spectroscope (NIRS), a mass spectrometer (MS) and standard bioreactor probes. One hundred and fifty sensor signals from the electronic nose, 1050 wavelength signals from the NIRS, carbon dioxide evolution rate calculated from mass spectrometer signals and standard bioreactor data (eg amount of substrate fed) were interrogated for their ability to model a bioprocess using MSPC. The models obtained were validated on a recombinant Escherichia coli fed‐batch process for tryptophan production. Limiting trajectories were defined in the MSPC models for warning, action, and process experience with respect to biomass and tryptophan concentrations. The results showed the capacity and robustness of MSPC models for monitoring with multi‐analysers and allowed a comparison of the different analysers' suitability for this kind of data processing. Furthermore, the results demonstrate that MSPC models provide a functional and versatile framework for coping with large information flows and are also suited to a variety of other bioprocessing monitoring and control tasks. © 2002 Society of Chemical Industry     

Electrokinetic transport of water and methanol in Nafion membranes as observed by NMR spectroscopy

Electrophoretic NMR (eNMR) and pulsed-field-gradient NMR (PFG-NMR) methods were used to study transport processes in situ and in a chemically resolved manner in the electrolyte of an experimental direct methanol fuel cell (DMFC) setup, constituted of several layers of Nafion 117. The measurements were conducted at room temperature for membranes fully swollen by methanol-water mixtures over a wide concentration interval. The experimental setup and the experimental protocol for the eNMR experiments are discussed in detail. The magnitude of the water and methanol self-diffusion coefficients show a good agreement with previously published data while the ratio of the two self-diffusion coefficients may indicate an imperfect mixing of the two solvent molecules. On the molecular level, the drag of water and methanol molecules by protons is roughly of the same magnitude, with the drag of methanol molecules increasing with increasing methanol content. The electro-osmotic drag defined on mass-flow basis increased for methanol from a low level with increasing methanol concentration while that of water remained roughly constant.     

Peptide/β-Peptoid Hybrids with Ultrashort PEG-Like Moieties: Effects on Hydrophobicity,Antibacterial Activity and Hemolytic Properties

PEGylation of antimicrobial peptides as a shielding tool that increases stability toward proteolytic degradation typically leads to concomitant loss of activity, whereas incorporation of ultrashort PEG-like amino acids (sPEGs) remains essentially unexplored. Here, modification of a peptide/β-peptoid hybrid with sPEGs was examined with respect to influence on hydrophobicity, antibacterial activity and effect on viability of mammalian cells for a set of 18 oligomers. Intriguingly, the degree of sPEG modification did not significantly affect hydrophobicity as measured by retention in reverse-phase HPLC. Antibacterial activity against both wild-type and drug-resistant strains of Escherichia coli and Acinetobacter baumannii (both Gram-negative pathogens) was retained or slightly improved (MICs in the range 2–16 µg/mL equal to 0.7–5.2 µM). All compounds in the series exhibited less than 10% hemolysis at 400 µg/mL. While the number of sPEG moieties appeared not to be clearly correlated with hemolytic activity, a trend toward slightly increased hemolytic activity was observed for analogues displaying the longest sPEGs. In contrast, within a subseries the viability of HepG2 liver cells was least affected by analogues displaying the longer sPEGs (with IC₅₀ values of ~1280 µg/mL) as compared to most other analogues and the parent peptidomimetic (IC₅₀ values in the range 330–800 µg/mL).     

Electrophysiological and Behavioral Responses of <Emphasis Type="Italic">Ips duplicatus</Emphasis> to Aggregation Pheromone in Inner Mongolia,China: Amitinol as a Potential Pheromone Component

Volatiles from Ips duplicatus male hindgut extracts and aeration samples of spruce logs colonized by the virgin males were analyzed by coupled gas chromatography–mass spectrometry (GC-MS), coupled gas chromatography–electroantennographic detection (GC-EAD), and field trapping bioassays in Inner Mongolia, China. GC-MS analyses showed that males from nuptial chambers (for reproduction) produced hindgut volatile profiles similar to those of maturation feeding males from the nonreproductive galleries. The known aggregation pheromone components, ipsdienol (Id) and E-myrcenol (EM) are the major constituents of this blend, followed by several minor bark beetle-related compounds: 2-methyl-3-buten-2-ol, ipsenol, cis-verbenol, verbenone, 2-phenylethanol, myrtenol, and trans-myrtanol. The enantiomeric composition of the Id from the male hindgut extracts was determined to be a racemic mixture (50/50) by enantioselective GC. GC-EAD experiments indicated that I. duplicatus antennae from both sexes responded strongly not only to the known aggregation pheromone components, Id and EM, but also to the other minor conspecific-produced compounds. The strongest antennal response was elicited by the major pheromone component, Id, which was ca. 2–3 times higher than that elicited by the second component, EM. Electroantennogram dose-responses indicated that antennal response threshold to Id was approximately 100 times lower than that of EM. No synergistic effects between these occurred at peripheral level. A strong and repeatable EAD response was found to a trace compound (flame ionization detection undetectable) from both hindgut and aeration samples. The compound was identified as amitinol (At) based on the retention time and a further EAD analysis of a synthetic mixture. In the field trapping experiments, At increased the attraction of I. duplicatus to the traps baited with a binary blend of EM/Id (1:1) in a synergistic manner when tested at a low release rate (1:1:0.1) but had no effect on catches at the high release rate (1:1:1). This result suggests that At might be a part of the Chinese I. duplicatus aggregation pheromone system. The production ratios of EM/Id from the Inner Mongolian population (EM/Id ≈ 1:2.0–4) were twice as high as those reported from Europe (EM/Id ≈ 1:9), corresponding well with the differences in the optimal response ratios.     

EVAPS蒸发系统的能源和环境解决方案

介绍了欧洲某家工厂采用9效蒸发系统后，能源和环境绩效都得到了提高。还介绍了另外一家工厂采用LCC分析得出的解决方案，改善了工厂的环境绩效和能源效率。     

Integrating a full carbon capture scheme onto a 450 MWe NGCC electric power generation hub for offshore operations: Presenting the Sevan GTW concept

Sevan Marine and Siemens have developed a floating power plant – entitled Sevan GTW (gas-to-wire) – based on Sevan’s cylindrical platform and Siemens’ SCC-800 combined cycle, and SINTEF has adapted a post-combustion CO₂ capture process for on board integration including compression and preconditioning of the CO₂. Main emphasis has been placed on developing an optimised conceptual design within the structural constraints, and assessing how efficient the capture unit may be operated in consideration of the dynamic behaviour induced by the sea on the absorber and desorber columns via the floating carrier. The rational behind this technology selection is the urgency in making appropriate steps for a quick start for remote power generation at sea with the inclusion of CCS to serve offshore oil and gas operations. This calls for modular power blocks made up by high efficient combined power cycles with post-combustion exhaust gas cleaning. From this point of view a system with four absorption columns and one desorber unit has been determined based on structured packing material. The capture process has been integrated with the power cycle in due consideration of the sea forces. It is shown that a permanent tilt becomes more important than periodic movements provided the harmonic periods are kept within a certain level (<20 s). Operational conditions and constraints vis-à-vis movements and trimming of the floater have been addressed and discussed with reference to available literature. This also includes the liquid hold-up and gas–liquid interfacial area in the absorption columns linked with tilting. Optimisation reveals that a reboiler duty of 3.77 GJ/ton CO₂ would result in the lowest capture cost. With a energy penalty of 9%-points the Sevan GTW concept presents itself as a realistic concept deemed to be within reach today.     

Bioenergy plantations or long-term carbon sinks? – A model based analysis

In order to mitigate climate change bio-productive land may be used mainly in two ways: afforestation with long-rotation forests with the primary aim to act as carbon sinks, and short-rotation forests that are used for energy purposes and thereby replace fossil fuels. Under an ambitious climate target, land that may be used for both bioenergy plantations and long-rotation forests, are likely to be scarce, and thereby competition between long-rotation forests and bioenergy plantations can be expected. The goal of the study is to analyze the cost-effectiveness of bioenergy plantations versus long-rotations forests aimed at capturing and storing carbon. The study is performed by solving and analyzing a linear optimization model that links the energy system, an afforestation sector and the pulp and timber market. Many earlier studies tend to suggest that long-rotation forests offer lower costs per ton of CO₂ avoided. Our study, however, shows that long-rotation forests for the purpose of carbon sequestration will not be cost-effective in the long run under a stringent climate policy. Thus, economic efficiency considerations tend to support short-rotation plantations for high carbon prices. The reason for this is that scarcity of land increases the opportunity cost of land, a feature which is generally not captured in static near-term analysis, but it is captured in a dynamic model like ours. For less stringent carbon targets long-rotation forests, that are harvested and sold as timber are cost-effective during a transient phase.     

Spatial encoding using a code division technique for fast ultrasound imaging

This paper describes a method for spatial encoding in synthetic transmit aperture ultrasound imaging. This allows several ultrasonic sources to be active simultaneously. The method is based on transmitting pseudorandom sequences to spatially encode the transmitters. The data can be decoded after only one transmission using the knowledge of the transmitted code sequences as opposed to other spatial encoding techniques, such as Hadamard or Golay encoding. This makes the method less sensitive to motion, and data can be acquired using fewer transmissions. The aim of this paper is to analyze the underlying theory and to test the feasibility in a physical system. The method has been evaluated in simulations using Field II in which the point-spread functions were simulated for different depths for a 7 MHz linear array transducer. A signal-to-noise ratio (SNR) simulation also was included in the study in which an improvement in SNR of approximately 1.5 dB was attained compared to the standard synthetic transmit aperture (STA) firing scheme. Considering the amount of energy transmitted, this value is low. A plausible explanation is given that is verified in simulation. The method also was tested in an experimental ultrasound scanner and compared to a synthetic transmit aperture ultrasound imaging scheme using a sinusoidal excitation. The performance of the proposed method was comparable to the reference with respect to axial and lateral resolution, but it displayed poorer contrast with sidelobe levels at approximately - 40 dB compared to the mainlobe.