Implementation of a Blind navigation method in outdoors/indoors areas

According to WHO statistics, the number of visually impaired people is increasing annually. One of the most critical necessities for visually impaired people is the ability to navigate safely. This paper proposes a navigation system based on the visual slam and Yolo algorithm using monocular cameras. The proposed system consists of three steps: obstacle distance estimation, path deviation detection, and next-step prediction. Using the ORB-SLAM algorithm, the proposed method creates a map from a predefined route and guides the users to stay on the route while notifying them if they deviate from it. Additionally, the system utilizes the YOLO algorithm to detect obstacles along the route and alert the user. The experimental results, obtained by using a laptop camera, show that the proposed system can run in 30 frame per second while guiding the user within predefined routes of 11 meters in indoors and outdoors. The accuracy of the positioning system is 8cm, and the system notifies the users if they deviate from the predefined route by more than 60 cm.Comment: 14 pages, 6 figures and 6 table

Carbon Nanotube Array Electrodes for Organic Thin Film Transistors

Depuis environ une vingtaine d’années, les transistors organiques à base de couches minces (acronyme en anglais, OTFT) se sont développés de façon impressionnante, passant de l'échelle de recherche au laboratoire à l'échelle de commercialisation. Les caractéristiques les plus intéressantes des OTFT sont leur compatibilité avec des substrats flexibles et leur méthode de fabrication, basée sur des techniques en solution. Les performances des OTFT sont influencées très fortement par les caractéristiques de l’interface semiconducteur organique/électrode métallique. L'interface semiconducteur organique/électrode métallique influence le processus d'injection de charge. En général, l'efficacité d'injection de charge dans les OTFT est limitée, parce que les niveaux électroniques du semiconducteur organique ne sont pas alignés avec le niveau de Fermi du métal de l’électrode. Dans ce mémoire de maîtrise, nous avons focalisé l'attention sur le processus d'injection de charge dans les OTFT utilisant comme matériau d'électrode des rangées de nanotubes de carbone monoparois (acronyme en anglais, SWCNT). Nous avons comparé les performances des OTFT basés sur des électrodes de type rangée de SWCNT avec les performances des OTFT utilisant des matériaux d'électrode plus conventionnels, tel que l’Au. Les OTFTs ont été fabriqués sur une couche de SiO2, obtenue par oxydation thermique d’une tranche de Si (100) fortement dopée (type n). La formation des rangées de SWCNT a été effectuée par la méthode de filtration sous vide des réseaux de SWCNT au-dessus de la surface de SiO2. La géométrie concentrique d'électrode a été réalisée par photolithographie et par développement. Nous avons observé des résultats très encourageants dans les cas de trois semiconducteurs organiques différents, tels que le poly-3 (hexyl) thiophène (P3HT), le dérivé du fullerène PCBM, et la ftalocyanine de tytanil (TiOPc).----------Abstract Over the past two decades, organic thin film transistors (OTFTs) have developed from the research laboratory scale to the scale of commercially feasible technology. The most attractive features of OTFTs are their low-cost manufacturing procedures and their compatibility with flexible substrates. The characteristics of the organic semiconductor/metal electrode interface dramatically affect the performance of OTFTs. For instance, charge carrier injection efficiency can be limited by the offset between the HOMO and LUMO energy levels of the organic semiconductor and the Fermi level of the metal electrode, since this offset leads to the formation of an energy barrier for charge carrier injection. This MSc work focuses on the use of single walled carbon nanotube (SWCNT) array electrodes, to improve the injection efficiency in OTFTs. A comparative approach has been adopted, based on the systematic comparison between SWCNT array electrode-based OTFTs with their, well investigated, Au electrode-based counterparts. An improvement in the injection characteristics of OTFTs making use of SWCNT array electrodes has been previously demonstrated in OTFTs based on organic semiconductors such as (p-type) pentacene and copper phthalocyanine and (n-type) phenyl-C61-butyric acid methyl ester (PCBM). In these previous studies, it has been hypothesized that the improvement of the charge carrier injection characteristics is mainly due to the one dimensional (1D) structure of SWCNTs, which favors tunneling injection across the injection barrier. To assess the general validity of this hypothesis, a large number of experiments need to be carried out with different organic semiconductors, belonging to different classes of materials (e.g., polymers and small molecules) and differently processed (e.g. solution processed and vacuum processed). In this project, the performance of OTFTs making use of SWCNT array electrodes has been investigated for thin films of Titanyl-phthalocyanine (TiOPc), Poly-3 (hexylthiophene) (P3HT), and P3HT/PCBM blends. TiOPc belongs to metal phthalocyanines (MPcs), which, due to their low solubility in organic solvents, are typically deposited by vacuum-based techniques. P3HT i

A functional assay for microRNA target identification and validation

MicroRNAs (miRNA) are a class of small RNA molecules that regulate numerous critical cellular processes and bind to partially complementary sequences resulting in down-regulation of their target genes. Due to the incomplete homology of the miRNA to its target site identification of miRNA target genes is difficult and currently based on computational algorithms predicting large numbers of potential targets for a given miRNA. To enable the identification of biologically relevant miRNA targets, we describe a novel functional assay based on a 3′-UTR-enriched library and a positive/negative selection strategy. As proof of principle we have used mir-130a and its validated target MAFB to test this strategy. Identification of MAFB and five additional targets and their subsequent confirmation as mir-130a targets by western blot analysis and knockdown experiments validates this strategy for the functional identification of miRNA targets

Chemical vapour deposition growth of graphene and hexagonal boron nitride, and a study of the electronic and corrosion inhibiting properties of hexagonal boron nitride

Graphene is an allotrope of carbon in the form of a two-dimensional (2D) material with zero bandgap. Hexagonal boron nitride (hBN), also known as white graphite, is a wide bandgap 2D material that has found use as an insulating dielectric layer in ultra-high mobility graphene devices, 2D heterostructures and tunneling devices. In this thesis, we report the chemical vapor deposition (CVD) growth and characterization of graphene and monolayer hBN. The growth of graphene and hBN was performed separately in a tube furnace on Cu foils using methane (CH4) and an ammonia borane (NH3-BH3) precursor, respectively. Raman spectroscopy confirmed that the CVD grown graphene is a monolayer of high quality. We have fabricated graphene field effect transistors and characterized their electrical properties to demonstrate material quality. Additionally, the CVD grown graphene was incorporated in a diverse range of applications, including large area graphene ion sensitive field effect transistors, suspended graphene varactors and an investigation of the role of hydrogenation on the electronic and thermal properties of graphene. We employed a variety of techniques to characterize CVD grown hBN. The morphology of the as-grown film along with the optimization of growth conditions to yield high coverage of monolayer hBN was studied by scanning electron microscopy. X-ray photoelectron spectroscopy confirmed the presence of boron and nitrogen in the CVD grown film as well as the expected stoichiometry. The electron diffraction pattern of suspended hBN films displayed a hexagonal crystal structure. A prominent Stokes Raman shift at 1369 cm-1 was observed in hBN transferred to Si/SiO2 substrates, revealing that our CVD grown hBN is of monolayer form. The optical properties of our hBN layers were probed by cathodoluminescence and UV-visible absorption spectroscopy. We report the first observation of in-plane charge transport in large area CVD grown monolayer hBN using a variety of electrode geometries. Ni electrodes were used to provide electrical contacts. We have observed a quadratic scaling of current with voltage at high bias corresponding to a space charge limited conduction mechanism, with a room temperature mobility reaching up to 0.01 cm2/Vs at electric fields up to 100 kV/cm in the absence of dielectric breakdown. The observation of in-plane charge transport highlights the semiconducting nature of monolayer hBN, and identifies hBN as a wide-gap 2D crystal capable of supporting charge transport at high field. Furthermore, we have examined the suitability of CVD grown monolayer hBN for inhibiting corrosion. Quantitative measurements of monolayer hBN as a Cu corrosion inhibitor were studied by use of cyclic voltammetry, Tafel analysis and electrochemical impedance spectroscopy. We have found that CVD grown monolayer hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating.The final contribution of this thesis is the growth of hBN directly on Si/SiO2 substrate via CVD. The main focus of this work is to produce metal-free, large-area, continuous and uniform hBN dielectric films on Si-based substrates ready to incorporate into devices without any transfer processing. We have also examined the effect of carrier gas flow rate on the thickness and roughness of the grown film in atmospheric pressure CVD. We have succeeded to grow large area hBN films with the thickness of ~ 2 nm and rms roughness of 0.6 nm (over 1 µm2) directly on Si/SiO2 substrates via atmospheric pressure CVD.Le graphène est un allotrope de carbone sous forme d'un matériau bidimensionnel (2D) avec une bande interdite nulle. Le nitrure de bore hexagonal (hBN) connu sous le nom de graphite blanc, est un matériau à large bande 2D qui est utilisé comme une couche diélectrique isolante dans des dispositifs de graphène à ultra-haute mobilité, des hétérostructures 2D et des dispositifs de tunnel. Dans cette thèse, nous signalons la croissance par dépôt chimique en phase vapeur (CVD) et la caractérisation du graphène et de la monocouche hBN. La croissance du graphène et du hBN a été effectuée séparément dans un four à tubes sur des feuilles de cuivre (Cu) en utilisant, respectivement, le méthane (CH4) et un précurseur d'ammoniac borane (NH3-BH3). Nous avons fabriqué des transistors à effet de champ en graphène et nous avons caractérisé leurs propriétés électriques afin de démontrer la qualité du matériau. Par ailleurs, le graphène développé par CVD a été utilisé dans une large gamme d'applications, y compris des transistors à effet de champ à base de graphène à grande surface sensible aux ions, des varacteurs de graphène suspendus et aussi l’étude du rôle de l'hydrogénation sur les propriétés thermiques et électroniques du graphène.Nous avons utilisé plusieurs techniques pour caractériser le hBN développé par CVD. La présence de bore et d'azote dans le film développé par CVD ainsi que leur stœchiométrie a été analysée par la spectroscopie photoélectronique par rayons X. Le diagramme de diffraction d'électrons des films hBN en suspension montrait une structure hexagonale cristalline. Un changement important de Stokes Raman à 1369 cm-1 a été observé dans le hBN transféré dans des substrats de Si/SiO2, révélant que notre hBN développé par CVD est sous forme de monocouche. Nous rapportons la première observation du transport de charge en plan dans la grande surface de monocouche hBN développée par CVD en utilisant une variété de géométries d'électrodes. Des électrodes Ni ont été servies pour fournir des contacts électriques. Nous avons observé une échelle quadratique du courant avec une tension à un biais élevé correspondant à un mécanisme de conduction à un mécanisme de conduction limité de charge spatiale, avec une mobilité à température ambiante atteignant jusqu'à 0,01 cm2 / Vs sur des champs électriques allant jusqu'à 100 kV / cm en l'absence de rupture diélectrique. L'observation du transport de charge en plan souligne la nature semi-conductrice du la monocouche hBN et identifie le hBN comme un cristal 2D à large intervalle capable de supporter le transport de charges dans un champ élevé. Par ailleurs, nous avons examiné la pertinence de la nanoculture des monocouches hBN développée par CVD pour inhiber la corrosion. Les mesures quantitatives de la monocouche hBN comme inhibiteur de corrosion du Cu ont été étudiées par la voltamétrie cyclique, l'analyse de Tafel et la spectroscopie d'impédance électrochimique. Nous avons constaté que les monocouches hBN développées par CVD peuvent réduire le taux de corrosion du Cu d'un ordre de grandeur comparé à Cu nu, ce qui suggère que cette couche ultra-fine peut être employée comme un revêtement atomiquement mince inhibant la corrosion.La contribution finale de cette thèse est avant tout la croissance de hBN directement sur le substrat Si/SiO2 via CVD. L'objectif principal de ce travail est de produire des films diélectriques hBN sans métal, de larges surfaces, continues et uniformes sur des substrats à base de Si prêts à être intégrés dans des dispositifs sans aucun traitement de transfert. Nous avons également examiné l'effet du débit du gaz porteur sur l'épaisseur et la rugosité du film développé. Nous avons réussi la croissance des films hBN à grande surface avec une épaisseur d’environ 2 nm et une rugosité rms de 0,6 nm directement sur les substrats Si/SiO2 par CVD en utilisant la pression atmosphérique

Nigella sativa powder for helicobacter pylori infected patients: a randomized, double-blinded, placebo-controlled clinical trial

Abstract Objective This double-blind, placebo-controlled, clinical trial was conducted to define the effects of Nigella sativa (N. Sativa) powder plus conventional medical treatment of Helicobacter pylori (H. pylori) on serum ghrelin level and appetite in H. pylori-infected patients. Methods In the present study, 51 H. pylori-positive patients were randomly allocated to treatment (n = 26) or placebo (n = 25) groups. They received 2 g/day N. Sativa with quadruple therapy or 2 g/day placebo plus quadruple therapy for 8 weeks. The serum level of ghrelin was assessed before and after the intervention. Appetite was evaluated at the onset and at the end of the intervention. Results At the end of the study, the appetite of the treatment group improved significantly compared with the placebo group (P = 0.02). Statistically, the difference in serum ghrelin levels between the study’s groups was insignificant (P > 0.05). Conclusion Supplementation with N. Sativa powder may be a beneficial adjunctive therapy in H. pylori-infected patients. Trial registration This study was registered in the Iranian Registry of Clinical Trials (IRCT20170916036204N7) on 08/08/2018

Crucial roles for protein kinase C isoforms in tumor-specific killing by Apoptin

Abstract The chicken anemia virus–derived protein apoptin induces apoptosis in a variety of human malignant and transformed cells but not in normal cells. However, the mechanisms through which apoptin achieves its selective killing effects are not well understood. We developed a lentiviral vector encoding a green fluorescent protein–apoptin fusion gene (LV-GFP-AP) that can efficiently deliver apoptin into hematopoietic cells. Apoptin selectively killed the human multiple myeloma cell lines MM1.R and MM1.S, and the leukemia cell lines K562, HL60, U937, KG1, and NB4. In contrast, normal CD34+ cells were not killed and maintained their differentiation potential in multilineage colony formation assays. In addition, dexamethasone-resistant MM1.R cells were found to be more susceptible to apoptin-induced cell death than the parental matched MM1.S cells. Death susceptibility correlated with increased phosphorylation and activation of the apoptin protein in MM1.R cells. Expression array profiling identified differential kinase profiles between MM1.R and MM1.S cells. Among these kinases, protein kinase Cβ (PKCβ) was found by immunoprecipitation and in vitro kinase studies to be a candidate kinase responsible for apoptin phosphorylation. Indeed, shRNA knockdown or drug-mediated inhibition of PKCβ significantly reduced apoptin phosphorylation. Furthermore, apoptin-mediated cell death proceeded through the upregulation of PKCβ, activation of caspase-9/3, cleavage of the PKCδ catalytic domain, and downregulation of the MERTK and AKT kinases. Collectively, these results elucidate a novel pathway for apoptin activation involving PKCβ and PKCδ. Further, they highlight the potential of apoptin and its cellular regulators to purge bone marrow used in autologous transplantation for multiple myeloma. Cancer Res; 70(18); 7242–52. ©2010 AACR.</jats:p

Carbon nanotube electrodes in organic transistors

International audienceThe scope of this Minireview is to provide an overview of the recent progress on carbon nanotube electrodes applied to organic thin film transistors. After an introduction on the general aspects of the charge injection processes at various electrode-semiconductor interfaces, we discuss the great potential of carbon nanotube electrodes for organic thin film transistors and the recent achievements in the field

Space-Charge Limited Transport in Large-Area Monolayer Hexagonal Boron Nitride

Hexagonal boron nitride (hBN) is a wide-gap material that has attracted significant attention as an ideal dielectric substrate for 2D crystal heterostructures. We report here the first observation of in-plane charge transport in large-area monolayer hBN, grown by chemical vapor deposition. The quadratic scaling of current with voltage at high bias corresponds to a space-charge limited conduction mechanism, with a room-temperature mobility reaching up to 0.01 cm²/(V s) at electric fields up to 100 kV/cm in the absence of dielectric breakdown. The observation of in-plane charge transport highlights the semiconducting nature of monolayer hBN, and identifies hBN as a wide-gap 2D crystal capable of supporting charge transport at high field. Future exploration of charge transport in hBN is motivated by the fundamental study of UV optoelectronics and the massive Dirac fermion spectrum of hBN