Systematic prediction error correction: a novel strategy for maintaining the predictive abilities of multivariate calibration models

The development of reliable multivariate calibration models for spectroscopic instruments in on-line/in-line monitoring of chemical and bio-chemical processes is generally difficult, time-consuming and costly. Therefore, it is preferable if calibration models can be used for an extended period, without the need to replace them. However, in many process applications, changes in the instrumental response (e.g. owing to a change of spectrometer) or variations in the measurement conditions (e.g. a change in temperature) can cause a multivariate calibration model to become invalid. In this contribution, a new method, systematic prediction error correction (SPEC), has been developed to maintain the predictive abilities of multivariate calibration models when e.g. the spectrometer or measurement conditions are altered. The performance of the method has been tested on two NIR data sets (one with changes in instrumental responses, the other with variations in experimental conditions) and the outcomes compared with those of some popular methods, i.e. global PLS, univariate slope and bias correction (SBC) and piecewise direct standardization (PDS). The results show that SPEC achieves satisfactory analyte predictions with significantly lower RMSEP values than global PLS and SBC for both data sets, even when only a few standardization samples are used. Furthermore, SPEC is simple to implement and requires less information than PDS, which offers advantages for applications with limited data.     

DNA-polymer micelles as nanoparticles with recognition ability

The Watson-Crick binding of DNA single strands is a powerful tool for the assembly of nanostructures. Our objective is to develop polymer nanoparticles equipped with DNA strands for surface-patterning applications, taking advantage of the DNA technology, in particular, recognition and reversibility. A hybrid DNA copolymer is synthesized through the conjugation of a ssDNA (22-mer) with a poly(ethylene oxide)-poly(caprolactone) diblock copolymer (PEO-b-PCl). It is shown that, in water, the PEO-b-PCl-ssDNA(22) polymer forms micelles with a PCl hydrophobic core and a hydrophilic corona made of PEO and DNA. The micelles are thoroughly characterized using electron microscopy (TEM and cryoTEM) and small-angle neutron scattering. The binding of these DNA micelles to a surface through DNA recognition is monitored using a quartz crystal microbalance and imaged by atomic force microscopy. The micelles can be released from the surface by a competitive displacement event.     

Algorithmes de décision et de construction dans les groupes libres

Sans résumé     

Constitution der β-Chinolinderivate und derm-Chlorchinoline

Ohne Zusammenfassung     

Efficient Thermo-Chemistry Tabulation for Non-Premixed Combustion at High-Pressure Conditions

Propellant injection and turbulent combustion in high-pressure engines is often dominated by real-gas effects. However, previous studies suggested that the departure of the fluid properties from an ideal gas behavior has only a limited effect on the laminar flame structure. This is due to the fact that chemical reactions take place in the flame zone where the temperature is sufficiently high and molecular interactions are negligible, i.e., the ideal gas assumption is valid. On the other hand, various experimental and numerical studies of injection processes at high-pressure conditions demonstrated that real-gas effects can have a strong impact on the turbulent flow. Mixing is influenced by the rapid change of fluid properties. In this work, we exploit the gap in the fidelity of the thermodynamics model needed to describe the laminar flame structure and that needed to describe the turbulent flow field. We then propose a new real-gas flamelet model with increased numerical performance. The computational cost of the new formulation is not significantly higher than that of an ideal gas simulation. The performance of the method is analyzed and the error that is introduced by our assumptions is assessed by comparison to more complete modeling. Finally, the method is used to simulate a turbulent jet flame emanating from a coaxial injector at supercritical pressure and cryogenic oxidizer temperature. The results are compared with experimental OH^? images giving evidence of the suitability of the present method.