Publications

2023

• Motion-Constrained GNSS/INS Integrated Navigation Method Based on BP Neural Network
  
  • Xu Ying
  • Wang Kun
  • Jiang Changhui
  • Li Zeyu
  • Yang Cheng
  • Liu Dun
  • Zhang Haiping
  Remote Sensing, MDPI, 2023, 15 (1), pp.154. The global navigation satellite system (GNSS) and inertial navigation system (INS) integrated navigation system have been widely used in Intelligent Transportation Systems (ITSs). However, the positioning error of integrated navigation systems is rapidly divergent when GNSS outages occur. Motion constraint and back propagation (BP) neural networks can provide additional knowledge to solve this issue. However, the predictions of a neural network have outliers and motion constraint is difficult to adapt according to the motion states of vehicles and boats. Therefore, this paper fused a BP neural network with motion constraints, and proposed a motion-constrained GNSS/INS integrated navigation method based on a BP neural network (MC-BP method). The pseudo-measurement of the GNSS was predicted using a fitting model trained by the BP neural network. At the same time, the prediction outliers were detected and corrected using motion constraint. To assess the performance of the proposed method, simulated and real data experiments were conducted with a vehicle on land and a boat offshore. A classical GNSS/INS integration algorithm, a motion-constrained GNSS/INS algorithm, and the proposed method were compared through data processing. Compared with the classical GNSS/INS integration algorithm and the motion-constrained GNSS/INS algorithm, the positioning accuracies of the proposed method were improved by 90% and 64%, respectively, in the vehicle land experiment. Similar performances were found in the offshore boat experiment. Using the proposed MC-BP method, improved meter-level-positioning results can be achieved with the GNSS/INS integration algorithm when GNSS outages occur. (10.3390/rs15010154)
  DOI : 10.3390/rs15010154
• Effects of formalin fixation on polarimetric properties of brain tissue: fresh or fixed?
  
  • Gros Éléa
  • Rodríguez-Núñez Omar
  • Felger Leonard
  • Moriconi Stefano
  • Mckinley Richard
  • Pierangelo Angelo
  • Novikova Tatiana
  • Vassella Erik
  • Schucht Philippe
  • Hewer Ekkehard
  • Maragkou Theoni
  Neurophotonics, Society of Photo-optical Instrumentation Engineers (SPIE), 2023, 10 (02), pp.025009. Significance: Imaging Mueller polarimetry (IMP) appears as a promising technique for real-time delineation of healthy and neoplastic tissue during neurosurgery. The training of machine learning algorithms used for the image post-processing requires large data sets typically derived from the measurements of formalin-fixed brain sections. However, the success of the transfer of such algorithms from fixed to fresh brain tissue depends on the degree of alterations of polarimetric properties induced by formalin fixation (FF). Aim: Comprehensive studies were performed on the FF induced changes in fresh pig brain tissue polarimetric properties. Approach: Polarimetric properties of pig brain were assessed in 30 coronal thick sections before and after FF using a wide-field IMP system. The width of the uncertainty region between gray and white matter was also estimated. Results: The depolarization increased by 5% in gray matter and remained constant in white matter following FF, whereas the linear retardance decreased by 27% in gray matter and by 28% in white matter after FF. The visual contrast between gray and white matter and fiber tracking remained preserved after FF. Tissue shrinkage induced by FF did not have a significant effect on the uncertainty region width. Conclusions: Similar polarimetric properties were observed in both fresh and fixed brain tissues, indicating a high potential for transfer learning. (10.1117/1.NPh.10.2.025009)
  DOI : 10.1117/1.NPh.10.2.025009
• Gold metallization of hybrid organic-inorganic polymer microstructures 3D printed by two-photon polymerization
  
  • Bretosh Kateryna
  • Hallais Simon
  • Chevalier-Cesar Clotaire
  • Zucchi Gaël
  • Bodelot Laurence
  Surfaces and Interfaces, Elsevier, 2023, 39, pp.102895. Two-photon polymerization is a femtosecond laser-based technique enabling printing of three-dimensional structures down to submicron resolution within photocurable polymers. Rendering the dielectric 3D printed structures conductive can be of great benefit for various applications in domains such as energy, photonics, or multifunctional devices. In this work, the microstructures of interest are made of a silicon-zirconium hybrid organic-inorganic polymer exhibiting low shrinkage during development. A simple and efficient metallization method by electroless plating is investigated to deposit a gold layer on the surface of the printed microstructures. The influence of the method parameters on the quality and properties of the deposited layer is studied. Among these parameters, the surface modification agent concentration and step duration, as well as the seeding solution concentration, must be adapted to the specific case of the considered hybrid microstructures. The concentration of metal ions in the plating bath is the most influential parameter on the morphology of the deposited gold layers. In particular, higher concentrations lead to smooth and continuous layers with electrical conductivities higher than half that of bulk gold. Finally, the deposited layers are shown to coat 3D printed microstructures of arbitrary shapes, thus confirming the conformality of the method at the micrometric scale. (10.1016/j.surfin.2023.102895)
  DOI : 10.1016/j.surfin.2023.102895
• Styrylpyrimidine chromophores with bulky electron-donating substituents: experimental and theoretical investigation
  
  • Hodée Maxime
  • Massue Julien
  • Achelle Sylvain
  • Fihey Arnaud
  • Tondelier Denis
  • Ulrich Gilles
  • Le Guen Françoise Robin
  • Katan Claudine
  Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2023, 25, pp.32699. Styrylpyrimidine with bulky 9,9-dimethylacridan, phenoxazine and phenothiazine electron-donating fragment were designed. Thermally activated delayed fluorescence (TADF) properties were expected for these structures. These chromophores exhibit peculiar emission properties. For 9,9-dimethylacridan and phenoxazine derivatives, a single emission highly sensitive to the polarity is observed in solution whereas for phenothiazine derivative a dual emission is observed in solution and is attributed to the coexistence of quasi-axial (Qax) and quasi-equatorial (Qeq) conformers. This study intends to understand with theoretical and experimental works, why the studied chromophores do not exhibit TADF properties, contrary to what was expected. The absence of phosphorescence both at room temperature and 77K tends to indicate the impossibility to harvest triplet states in these systems. Wave-function based calculations show that for both conformers of the three chromophores the S1-T1 splitting is significantly larger than 0.2 eV. The second triplet state T2 of Qeq conformers is found very close in energy to the singlet S1 state, but S1 and T2 states possess similar charge transfer characters. This prevents efficient spin-orbit coupling between the states, which is consistent with the absence of TADF. (10.1039/D3CP03705C)
  DOI : 10.1039/D3CP03705C
• Characterization of vine, Vitis vinifera, leaves by Mueller polarimetric microscopy
  
  • Bugami B. Al
  • Su Y.
  • Rodríguez C.
  • Lizana A.
  • Campos J.
  • Durfort M.
  • Ossikovski R.
  • Garcia-Caurel E.
  Thin Solid Films, Elsevier, 2023, 764, pp.139594. In this work, we present the study of vine leaves, Vitis vinifera, performed by imaging polarimetry in the visible (at the wavelength of 530 nm). The purpose is to demonstrate, on a case study example, the high potential of imaging polarimetry and of polarimetric microscopy, in particular, for the characterization of vegetal tissues. The analysis of the Mueller matrix image of the sample provided by the polarimetric microscope by means of a matrix decomposition protocol yields a series of observables that are directly related to the fundamental physical properties that characterize the sample. Birefringence and dichroism are related to the structural properties of the medium and can be advantageously used as non-chemical, non-contact, non-destructive and non-toxic markers to highlight the presence of specific structures in the probed sample. Polarimetric images may also be used to enhance the contrast of the measured images. Specifically, we use the polarimetric properties and the depolarization indices to unveil the presence of structures such as raphides, some of them invisible under non-polarized light, and to investigate their properties. (10.1016/j.tsf.2022.139594)
  DOI : 10.1016/j.tsf.2022.139594
• Robustness of the wide-field imaging Mueller polarimetry for brain tissue differentiation and white matter fiber tract identification in a surgery-like environment: an ex vivo study
  
  • Felger Leonard
  • Rodríguez-Núñez Omar
  • Gros Éléa
  • Maragkou Theoni
  • Mckinley Richard
  • Moriconi Stefano
  • Murek Michael
  • Zubak Irena
  • Novikova Tatiana
  • Pierangelo Angelo
  • Schucht Philippe
  Biomedical optics express, Optical Society of America - OSA Publishing, 2023, 14 (5), pp.2400. During neurooncological surgery, the visual differentiation of healthy and diseased tissue is often challenging. Wide-field imaging Muller polarimetry (IMP) is a promising technique for tissue discrimination and in-plane brain fiber tracking in an interventional setup. However, the intraoperative implementation of IMP requires realizing imaging in the presence of remanent blood, and complex surface topography resulting from the use of an ultrasonic cavitation device. We report on the impact of both factors on the quality of polarimetric images of the surgical resection cavities reproduced in fresh animal cadaveric brains. The robustness of IMP is observed under adverse experimental conditions, suggesting a feasible translation of IMP for in vivo neurosurgical applications. (10.1364/BOE.486438)
  DOI : 10.1364/BOE.486438
• Electric Field-Induced Nano-Assembly Formation: First Evidence of Silicon Superclusters with a Giant Permanent Dipole Moment
  
  • Jardali Fatme
  • Tran Jacqueline
  • Liège Frédéric
  • Florea Ileana
  • Leulmi Mohamed
  • Vach Holger
  Nanomaterials, MDPI, 2023, 13 (15), pp.2169. The outstanding properties of silicon nanoparticles have been extensively investigated during the last few decades. Experimental evidence and applications of their theoretically predicted permanent electric dipole moment, however, have only been reported for silicon nanoclusters (SiNCs) for a size of about one to two nanometers. Here, we have explored the question of whether suitable plasma conditions could lead to much larger silicon clusters with significantly stronger permanent electric dipole moments. A pulsed plasma approach was used for SiNC production and surface deposition. The absorption spectra of the deposited SiNCs were recorded using enhanced darkfield hyperspectral microscopy and compared to time-dependent DFT calculations. Atomic force microscopy and transmission electron microscopy observations completed our study, showing that one-to-two-nanometer SiNCs can, indeed, be used to assemble much larger ”superclusters” with a size of tens of nanometers. These superclusters possess extremely high permanent electric dipole moments that can be exploited to orient and guide these clusters with external electric fields, opening the path to the controlled architecture of silicon nanostructures. (10.3390/nano13152169)
  DOI : 10.3390/nano13152169
• Liquid Shear Exfoliation of MoS2: Preparation, Characterization, and NO2-Sensing Properties
  
  • Ni Pingping
  • Dieng Mbaye
  • Vanel Jean-Charles
  • Florea Ileana
  • Bouanis Fatima Zahra
  • Yassar Abderrahim
  Nanomaterials, MDPI, 2023, 13 (18), pp.2502. 2D materials possess great potential to serve as gas-sensing materials due to their large, specific surface areas and strong surface activities. Among this family, transition metal chalcogenide materials exhibit different properties and are promising candidates for a wide range of applications, including sensors, photodetectors, energy conversion, and energy storage. Herein, a high-shear mixing method has been used to produce multilayered MoS2 nanosheet dispersions. MoS2 thin films were manufactured by vacuum-assisted filtration. The structural morphology of MoS2 was studied using ς-potential, UV–visible, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The spectroscopic and microscopic analyses confirm the formation of a high-crystalline MoS2 thin film with good inter-sheet connectivity and relative thickness uniformity. The thickness of the MoS2 layer is measured to be approximately 250 nm, with a nanosheet size of 120 nm ± 40 nm and a number of layers between 6 and 9 layers. Moreover, the electrical characteristics clearly showed that the MoS2 thin film exhibits good conductivity and a linear I–V curve response, indicating good ohmic contact between the MoS2 film and the electrodes. As an example of applicability, we fabricated chemiresistive sensor devices with a MoS2 film as a sensing layer. The performance of the MoS2-chemiresistive sensor for NO2 was assessed by being exposed to different concentrations of NO2 (1 ppm to 10 ppm). This sensor shows a sensibility to low concentrations of 1 ppm, with a response time of 114 s and a recovery time of 420 s. The effect of thin-film thickness and operating temperatures on sensor response was studied. The results show that thinner film exhibits a higher response to NO2; the response decreases as the working temperature increases. (10.3390/nano13182502)
  DOI : 10.3390/nano13182502