Growth and structural characterization of molecular superlattice of quaterrylene and N,N′-dioctyl-3,4,9,10-perylenedicarboximide

A molecular superlattice consisting of alternate layers of N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C₈) and quaterrylene was prepared by using an ultra-slow deposition technique. Film growth under equilibrium conditions with precise optimization of the substrate temperature enabled the layer-by-layer stacking of hetero-molecules at a single-layer level. The morphology of the films and the orientation of the molecules in each layer were analyzed by atomic force microscopy (AFM) and an X-ray reflection (XRR) technique.     

Identification of precancerous lesions by multispectral gastroendoscopy

Gastric cancer is one of the fifth most deadly cancers worldwide. Nowadays the diagnosis is performed through gastroendoscopy under white light and histological analysis. However, the precancerous lesions are multifocalized and present low differences with respect to healthy tissue. Several systems have been proposed based on light tissue interaction to improve the visualization of malignancies. However, these systems are limited to few wavelengths. In this paper, we propose a minimally invasive technique based on multispectral imaging and a methodology to identify malignancies in the stomach. We developed a multispectral gastroendoscopic system compatible with current gastroendoscopes, where only the illumination is changed. The spectra are extracted from the acquired multispectral images in order to compute statistical features that are used to classify the data in two classes: healthy and malignant. The features are ranked by pooled variance t test to train three classifiers. Neural networks using generalized relevance learning vector quantization, support vector machine (SVM) with a Gaussian kernel and k-nn are evaluated using leave one patient out cross-validation. Taking into consideration the data collected in this work, the quantitative results from the classification using SVM show high accuracy and sensitivity using a low number of features. These results show the ability to discriminate malignancies of the gastric tissue. Therefore, multispectral imaging could help in the identification of malignancies during gastroendoscopy.     

Ultrashort pulse laser processing of silica at high repetition rates—from network change to residual strain

We report on the analysis of silica-based glasses after processing with ultrashort laser pulses at high repetition rates. Heat accumulation leads to strong local heating of the glass. The subsequent quenching results in a fictive temperature rise that scales with the repetition rate. Consequently, the relative volume change leads to residual tensile strain within the modified volume of larger than 10⁻³, which is confirmed by wide-angle X-ray scattering (WAXS) measurements. Studying the surface topography after cleaving of laser-modified regions allows for quantification of the corresponding elastic strain as well as the glass density behavior on the fictive temperature.     

Catalytic Enantioselective Total Synthesis of Riccardiphenol B

The first catalytic enantioselective total synthesis of riccardiphenol B, a sesquiterpene derivative isolated from a Japanese collection of the liverwort Riccardia crassa, has been achieved. A copper‐catalyzed asymmetric conjugate addition of trimethylaluminum was used at an early stage to generate the quaternary stereogenic center with high enantiomeric excess. The corresponding sterically encumbered aluminum enolate was directly trapped with an α‐amino ether, allowing after oxidation, the release of a key intermediate in the total synthesis of the target natural product.

     

Fracture behavior of carbon nanotube/carbon microfiber hybrid polymer composites

Growing carbon nanotubes (CNTs) on the surface of fibers has the potential to modify fiber–matrix interfacial adhesion, enhance composite delamination resistance, and possibly improve toughness. In the present study, aligned CNTs were grown upon carbon fabric via chemical vapor deposition. Continuously monitored single-fiber composite fragmentation tests were performed on pristine and CNT-grafted fibers embedded in epoxy, and single-laminate compact-tension specimens were tested for fracture behavior. A significant increase (up to 20 %) was observed in the interfacial adhesion, at the cost of a decrease in the fiber tensile strength. As a result, the maximum load of the composite was decreased, but its residual load-bearing capacity more than doubled. The likely sources of these effects are discussed, as well as their implications.     

How visual fatigue and discomfort impact 3D-TV quality of experience: a comprehensive review of technological, psychophysical, and psychological factors

The quality of experience (QoE) of 3D contents is usually considered to be the combination of the perceived visual quality, the perceived depth quality, and lastly the visual fatigue and comfort. When either fatigue or discomfort are induced, studies tend to show that observers prefer to experience a 2D version of the contents. For this reason, providing a comfortable experience is a prerequisite for observers to actually consider the depth effect as a visualization improvement. In this paper, we propose a comprehensive review on visual fatigue and discomfort induced by the visualization of 3D stereoscopic contents, in the light of physiological and psychological processes enabling depth perception. First, we review the multitude of manifestations of visual fatigue and discomfort (near triad disorders, symptoms for discomfort), as well as means for detection and evaluation. We then discuss how, in 3D displays, ocular and cognitive conflicts with real world experience may cause fatigue and discomfort; these includes the accommodation–vergence conflict, the inadequacy between presented stimuli and observers depth of focus, and the cognitive integration of conflicting depth cues. We also discuss some limits for stereopsis that constrain our ability to perceive depth, and in particular the perception of planar and in-depth motion, the limited fusion range, and various stereopsis disorders. Finally, this paper discusses how the different aspects of fatigue and discomfort apply to 3D technologies and contents. We notably highlight the need for respecting a comfort zone and avoiding camera and rendering artifacts. We also discuss the influence of visual attention, exposure duration, and training. Conclusions provide guidance for best practices and future research.     

Multi-criteria performance analysis for decision making in project management

This study is focused on decision support in the context of product and service development projects. Decision support requires the capacity to characterize the current state of the project (performance evaluation) and the decision-maker's point of view. However, the different projects’ stakeholders do not have the same needs in terms of performance evaluation to support their decision-making processes. Furthermore, in some cases controlling project performance using the elementary components of the Iron Triangle (Cost, Time and Quality) alone seems inefficient. This paper proposes a new multi-dimensional Project Performance Measurement System that would enable managers to deal with the volume of data. The proposition integrates the only character of each project (tasks, objectives, decision-makers personality and competences), several good practices in terms of universal project management dimensions on the one hand, and in terms of performance analysis on the other hand. Then, we show how an aggregation tool called MACBETH is used to analyze the performance measures according to project managers’ own performance interests. A case study illustrates the proposed system.