On the design of approximate non‐linear parametric controllers

This paper focuses on the design of non‐linear parametric controllers, around a nominal input/output trajectory of a discrete‐time non‐linear system. The main result provided herein is a relationship between the tracking performance of the closed‐loop control system in the neighbourhood of a nominal trajectory, and some local features (the first‐order linear approximations about the nominal trajectory) of the non‐linear mappings which characterize the plant and the feedback controller. Such a result can be used to predict the dynamic behaviour of the control system, and to reduce the computational complexity of the optimization task associated with the tuning of the parametric feedback controller. Copyright © 2000 John Wiley & Sons, Ltd.     

Design and off-line programming of a robotic tape winding cell

Tape winding is a variation on filament winding, in which a single tape is used instead of a bundle of independently tensioned rovings. At K.U. Leuven, a robotic tape winding cell has been developed. Starting from data of the fiber paths, a collision-free off-line robot program is generated. To avoid collisions a heuristic method is used. The method has been validated by winding of a T-piece.     

Integration of Mutational Signature Analysis with 3D Chromatin Data Unveils Differential AID-Related Mutagenesis in Indolent Lymphomas

Activation-induced deaminase (AID) is required for somatic hypermutation in immunoglobulin genes, but also induces off-target mutations. Follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL), the most frequent types of indolent B-cell tumors, are exposed to AID activity during lymphomagenesis. We designed a workflow integrating de novo mutational signatures extraction and fitting of COSMIC (Catalogue Of Somatic Mutations In Cancer) signatures, with tridimensional chromatin conformation data (Hi-C). We applied the workflow to exome sequencing data from lymphoma samples. In 33 FL and 30 CLL samples, 42% and 34% of the contextual mutations could be traced to a known AID motif. We demonstrate that both CLL and FL share mutational processes dominated by spontaneous deamination, failures in DNA repair, and AID activity. The processes had equiproportional distribution across active and nonactive chromatin compartments in CLL. In contrast, canonical AID activity and failures in DNA repair pathways in FL were significantly higher within the active chromatin compartment. Analysis of DNA repair genes revealed a higher prevalence of base excision repair gene mutations (p = 0.02) in FL than CLL. These data indicate that AID activity drives the genetic landscapes of FL and CLL. However, the final result of AID-induced mutagenesis differs between these lymphomas depending on chromatin compartmentalization and mutations in DNA repair pathways.     

Attaching of flexible chains to novolacs on the basis of bisphenol A

Networks containing both flexible segments and rigid structures were synthesized on the basis of bisphenol A novolacs and diglycidylether of butanediol using imidazole as an accelerator. A stoichiometric ratio between epoxy groups and phenolic groups of the novolacs leads to networks with methylene bridges as network junctions. In contrast to this, the same reaction with bisphenol A leads to completely soluble products. The glass transition temperature of this soluble material is considerably lower than the glass transition temperature of the networks. Increasing content of methylene bridges in the novolacs leads to an increase of the glass transition temperature of the networks and to a decrease of the δc_p value at the glass transition. Furthermore, epoxy excess leads to networks with rubber-structure of the bisphenol A novolac used in the reaction with the diglycidylether. It was found that conformations with intramolecular hydrogen bondings exist between phenolic hydroxyl groups, which considerably influence the reactivity of the novolac with the epoxy group. © 1996 John Wiley & Sons, Inc.     

Development and validation of an HPLC method with fluorescence detection for the determination of fluorescent whitening agents migrating from plastic beverage cups

An HPLC method with fluorescence detection has been developed and validated for the quantification of six fluorescent whitening agents (FWA) in plastic beverage cups after extraction and in food simulants after migration at 70°C for 2 h. The sensitivity of the method was high with LODs ranging from 0.053 to 0.251 μg kg^?1 and LOQs from 0.107 to 0.504 μg kg^?1. Accuracy and precision were highly acceptable, with recoveries greater than 82% and RSDs (%) below 16%. The expanded combined uncertainty was found to be less than 23% for the measurements of all studied FWAs. In extracting the analytes from food contact materials (FCM), accelerated solvent extraction (ASE) and Soxhlet extraction were applied using ethanol as the extraction solvent. The results obtained for FWA in 10 different food plastic cups, made from different polymers, were compared. The ASE technique proved to be faster, more effective and efficient than Soxhlet extraction. Migration tests with official food simulants from Regulation (EU) No 10/2011 showed that the substances studied could potentially migrate using the selected migration conditions. The most pronounced effect was observed in case of simulant D1 (50% w/v ethanol in water). The analytical method proved to be a simple, fast, sensitive and reliable tool for the simultaneous quantification of six of the most used FWAs in both FCM extracts and food simulants after migration experiments.     

De Novo Missense Mutations in TNNC1 and TNNI3 Causing Severe Infantile Cardiomyopathy Affect Myofilament Structure and Function and Are Modulated by Troponin Targeting Agents

Rare pediatric non-compaction and restrictive cardiomyopathy are usually associated with a rapid and severe disease progression. While the non-compaction phenotype is characterized by structural defects and is correlated with systolic dysfunction, the restrictive phenotype exhibits diastolic dysfunction. The molecular mechanisms are poorly understood. Target genes encode among others, the cardiac troponin subunits forming the main regulatory protein complex of the thin filament for muscle contraction. Here, we compare the molecular effects of two infantile de novo point mutations in TNNC1 (p.cTnC-G34S) and TNNI3 (p.cTnI-D127Y) leading to severe non-compaction and restrictive phenotypes, respectively. We used skinned cardiomyocytes, skinned fibers, and reconstituted thin filaments to measure the impact of the mutations on contractile function. We investigated the interaction of these troponin variants with actin and their inter-subunit interactions, as well as the structural integrity of reconstituted thin filaments. Both mutations exhibited similar functional and structural impairments, though the patients developed different phenotypes. Furthermore, the protein quality control system was affected, as shown for TnC-G34S using patient’s myocardial tissue samples. The two troponin targeting agents levosimendan and green tea extract (-)-epigallocatechin-3-gallate (EGCg) stabilized the structural integrity of reconstituted thin filaments and ameliorated contractile function in vitro in some, but not all, aspects to a similar degree for both mutations.     

Measurement of concrete strength using the emission intensity ratio between Ca(II) 396.8 nm and Ca(I) 422.6 nm in a Nd:YAG laser-induced plasma

An experiment to investigate the potential of a laser-induced plasma method for determining concrete compressive strength was conducted by focusing a Nd:YAG laser on concrete samples with different degrees of compressive strength. This technique was developed in light of the role of the shock wave in the generation of a laser-induced plasma. It was found that the speed of the shock front depends on the hardness of the sample. It was also found that a positive relationship exists between the speed of the shock front and the ionization rate of the ablated atoms. Hence, the ratio of the intensity between the Ca(II) 396.8 nm and Ca(I) 422.6 nm emission lines detected from the laser-induced plasma can be used to examine the hardness of the material. In fact, it was observed that the ratio changes with respect to the change in the concrete compressive strength. The findings also show that the ratio increases with time after the cement is mixed with water.     

3D Direct Laser Writing of Nano‐ and Microstructured Hierarchical Gecko‐Mimicking Surfaces

Applying 3D direct laser writing, artificial hierarchical gecko‐type structures are designed and fabricated down to nanometer dimensions. In this way, the elastic modulus and the length scale of the gecko's setae are very closely matched. Direct laser writing is a very flexible rapid prototyping method allowing the fabrication of arbitrary nanostructures. Since the parameters of the structures can be easily changed, this technique is perfect for design studies of dry adhesives. Measuring the adhesional forces by atomic force microscopy, the influence of several design parameters like density, aspect ratio, and tip‐shape on dry adhesion performance are systematically examined. In this way, it is revealed that hierarchy is favorable for artificial gecko‐inspired dry adhesives made of stiff materials on the nanometer scale.     

Airflow elicits a spider's jump towards airborne prey. I. Airflow around a flying blowfly

The hunting spider Cupiennius salei uses airflow generated by flying insects for the guidance of its prey-capture jump. We investigated the velocity field of the airflow generated by a freely flying blowfly close to the flow sensors on the spider''s legs. It shows three characteristic phases (I–III). (I) When approaching, the blowfly induces an airflow signal near the spider with only little fluctuation (0.013 ± 0.006 m s⁻¹) and a strength that increases nearly exponentially with time (maximum: 0.164 ± 0.051 m s⁻¹ s.d.). The spider detects this flow while the fly is still 38.4 ± 5.6 mm away. The fluctuation of the airflow above the sensors increases linearly up to 0.037 m s⁻¹ with the fly''s altitude. Differences in the time of arrival and intensity of the fly signal at different legs probably inform the spider about the direction to the prey. (II) Phase II abruptly follows phase I with a much higher degree of fluctuation (fluctuation amplitudes: 0.114 ± 0.050 m s⁻¹). It starts when the fly is directly above the sensor and corresponds to the time-dependent flow in the wake below and behind the fly. Its onset indicates to the spider that its prey is now within reach and triggers its jump. The spider derives information on the fly''s position from the airflow characteristics, enabling it to properly time its jump. The horizontal velocity of the approaching fly is reflected by the time of arrival differences (ranging from 0.038 to 0.108 s) of the flow at different legs and the exponential velocity growth rate (16–79 s⁻¹) during phase I. (III) The air flow velocity decays again after the fly has passed the spider.