Luminescence studies of Europium (III) - D-glucosamine complexes in water

LUMINESCENCE STUDIES OF EUROPIUM(III) - D-GLUCOSAMINE COMPLEXES IN WATER by Triny Trinh Pham Lanthanide complexation interactions measured by luminescence have become interesting topic in recent years. Europium is a rare earth metal and the Eu(III) ion is a hard acid; when Eu(III) and a monosaccharide ligand are present, a complex may be formed. The goal is to determine the equilibrium constant KEuL between the europium ion and a D-glucosamine ligand. At 25oC and pH ~ 7.40, a physiologically important pH, adding D-glucosamine enhanced the luminescence of 0.0025 M Eu(III). As the concentration of ligand increased, the emission intensity was also increased. The measurement of a hypersensitive peak at 614 nm indicated a complex reaction at pH ~ 7.40. The equilibrium constant of KEuL was found to be 29.24. Based on the FTIR and laser experiments, the results confirmed that D-glucosamine attached to the europium ion (Eu3+) at pH ~ 7.40; there was no evidence that hydrolyzed Eu(III) was present in the complexation

Formation Control of Rigid Graphs with a Flex Node Addition

This paper examines stability properties of distance-based formation control when the underlying topology consists of a rigid graph and a flex node addition. It is shown that the desired equilibrium set is locally asymptotically stable but there exist undesired equilibria. Specifically, we further consider two cases where the rigid graph is a triangle in 2-D and a tetrahedral in 3-D, and prove that any undesired equilibrium point in these cases is unstable. Thus in these cases, the desired formations are almost globally asymptotically stable.Comment: The full version of this paper with general extensions has been submitted to a journal for publicatio

Economic performance of Vietnam, 1976-2000: New evidence from input-output model

This study provides a concise introduction to the economic history of Vietnam from 1976 to present. We identify different phases of the development of the Vietnamese economy, from its unification after a Vietnam war to the current phases of the transition (1989-2000) and propose a specific pattern of transition in the case of Vietnam. This research is the first attempt to make a synthesis quantitative analysis of socio-economic aggregate data during different phases of the Vietnamese economy in 1986-2000, in which different national input-output tables (1989, 1996 and 2000) in constant prices have been employed. The economic performances are investigated from three aspects: (i) evolution of domestic final demand; (ii) evolution of international trade structure and (iii) the technological change. The analysis shows economic history of Vietnam from 1986 up to present as a continuous evolutionary process and integration in to the international market is inevitable. Government programmes only played a vital role of accommodator to the economic changes of the Vietnamese economy.Input-output analysis, Vietnamese economy, Economic history, Transition economy, Macro-economic policy

The debates and the long-awaited reform

Trung Tran, Phuong-Thao T. Trinh, Thu-Trang Vuong, Hiep-Hung Pham (2019). Chapter 1. The debates and the long-awaited reform. In Quan-Hoang Vuong, Trung Tran (Eds.), The Vietnamese Social Sciences at a Fork in the Road (pp. 17–32). Warsaw, Poland: De Gruyter / Sciendo. DOI:10.2478/9783110686081-006 Online ISBN: 9783110686081 © 2019 De Gruyter / Sciend

Performance of free-space QKD systems using SIM/BPSK and dual-threshold/direct-detection

This paper proposes a novel free-space quantum key distribution (QKD) system using subcarrier intensity-modulation (SIM) binary phase-shift-keying (BPSK) and dual-threshold/direct-detection (DT/DD) receiver with an avalanche photodiode (APD). The proposed system enables the adoption of well-developed analytical models in conventional free-space optical (FSO) communications and achieves the QKD function with a simple configuration. We analytically investigate the design criteria for transmitter and receiver, in particular, the modulation depth and the setting for dual-threshold in the context of security requirement of QKD systems. The quantum bit error rate (QBER) and the ergodic secret-key rate of the proposed system are analytically derived in closed-form expressions, considering the channel loss, atmospheric turbulence modeled by the log-normal distribution, and receiver noises. Monte-Carlo (M-C) simulations are also implemented to validate the analytical results, and numerical results confirm the feasibility of the proposed system

Observation des influences du changement du couvert forestier sur le comportement hydrologique de grands bassins versants tropicaux à l'aide de la télédétection numérique cas du bassin versant de Dong Nai, Viet Nam

Monitoring hydrological behavior of a large tropical watershed following a forest cover variation has an important role in water resource management planning as well as for forest sustainable management. Traditional methods in forest hydrology studies are Experimental watersheds, Upstream-downstream, Experimental plots, Statistical regional analysis and Watershed simulation. Those methodes have limitations for large watersheds concerning the monitoring time, the lack of input data especially about forest cover and the capacity of extrapolating results accurately in terms of large watersheds. Moreover, there is still currently a scientific debate in forest ecology on relation between water and forest. The reason of this problem comes from geographical differences in publication concerning study zones, experimental watershed size and applied methods. It gives differences in the conclusions on the influence of tropical forest cover change on the changes of outlet water and yet on the yearly runoff in terms of large watershed. In order to exceed the limitations of actual methods, to solve the difficulty of acquiring forest cover data and to have a better understanding of the relation between tropical forest cover change and hydrological behavior evolution of a large watershed, it is necessary to develop a new approach by using numeric remote sensing. We used the watershed of Dong Nai as a case study. Results show that a fusion between TM and ETM+ Landsat image series and hydro-meteorologic data allow us to observe and detect flooding trends and flooding peaks after an intensive forest cover change from 16% to 20%. Flooding frequency and flooding peaks have clearly decreased when there is an increase of the forest cover from 1983 to 1990. The influence of tropical forest cover on the hydrological behavior is varying with geographical locations of watershed. There is a significant relation between forest cover evolution and environmental facteurs as the runoff coefficient (R = 0,87) and the yearly precipitation (R = 0,93)

Ligand Design for Dual Property Single Molecule Magnets

This thesis describes two different approaches for the preparation of polynuclear clusters with interesting structural, magnetic and optical properties. Firstly, exploiting p-tert-butylcalix[4]arene (TBC4) macrocycles together with selected Ln(III) ions for the assembly of emissive single molecule magnets, and secondly the preparation and coordination of a chiral mpmH ligand with selected 3d transition metal ions, working towards the discovery of chiral polynuclear clusters. In Project 1, the coordination chemistry of the TBC4 macrocycle together with Dy(III) and Tb(III) afforded two Ln6[TBC4]2 complexes that have been structurally, magnetically and optically characterized. X-ray diffraction studies reveal that both complexes contain an octahedral core of Ln6 ions capped by two fully deprotonated TBC4 macrocycles. Although the unit cells of the two complexes are very similar, the coordination geometries of their Ln(III) ions are subtly different. Variable temperature ac magnetic susceptibility studies reveal that both complexes display single molecule magnet (SMM) behaviour in zero dc field and the energy barriers and associated pre-exponential factors for each relaxation process have been determined. Low temperature solid state photoluminescence studies reveal that both complexes are emissive; however, the f-f transitions within the Dy6 complex were masked by broad emissions from the TBC4 ligand. In contrast, the Tb(III) complex displayed green emission with the spectrum comprising four sharp bands corresponding to 5D4 → 7FJ transitions (where J = 3, 4, 5 and 6), highlighting that energy transfer from the TBC4 macrocycle to the Tb(III) ion is more effective than to Dy. Examples of zero field Tb(III) SMMs are scarce in the chemical literature and the Tb6[TBC4]2 complex represents the first example of a Tb(III) dual property SMM assembled from a p-tert-butylcalix[4]arene macrocycle with two magnetically derived energy barriers, Ueff of 79 and 63 K. In Project 2, the coordination of both enantiomers of the chiral ligand, α-methyl-2-pyridinemethanol (mpmH) to Ni(II) and Co(II) afforded three polynuclear clusters that have been structurally and magnetically characterized. The first complex, a Ni4 cluster of stoichiometry [Ni4(O2CCMe3)4(mpm)4]·H2O crystallizes in a distorted cubane topology that is well known in Ni(II) cluster chemistry. The final two Co(II) complexes crystallize as a linear mixed valence trimer with stoichiometry [Co3(mpm)6]·(ClO4)2, and a Co4 mixed valence complex [Co(II)¬2Co(III)2(NO3)2(μ-mpm)4(ONO2)2], whose structural topology resembles that of a defective double cubane. All three complexes crystallize in chiral space groups and circular dichroism experiments further confirm that the chirality of the ligand has been transferred to the respective coordination complex. Magnetic susceptibility studies reveal that for all three complexes, there are competing ferro- and antiferromagnetic exchange interactions. The [Co(II)¬2Co(III)2(NO3)2(μ-mpm)4(ONO2)2] complex represents the first example of a chiral mixed valence Co4 cluster with a defective double cubane topology

Suivi de l'utilisation du sol à l'aide de l'image TM de landsat et de la géomatique le cas du district de Bao Loc, province de Lam Dong, Viet Nam (1992-1998)

Résumé: Ce mémoire a été rédigé dans le cadre du projet "Le Défi Forestier au Viet nam" avec l’aide la financière du Centre de Recherches pour le Développement International (CRDI). Lors de sa première phase (1994-1996), les résultats ont constaté un fort taux de changement dans la couverture végétale forestière de la province de Lam Dong, les causes identifiées sont la pression démographique et l'expansion agricole, en particulier le remplacement de une couverture forestière par la couverture agro-industriels que (le théier, le caféier, le mûrier...) Dans ce contexte, la présente recherche a été localisée sur l'intégration des données satellitaires (image TM de Landsat) dans un SIG pour diagnostiquer et évaluer le changement de l'utilisation du sol au niveau communal. Ceci nous permettra d'apporter la réponse à certaines questions comme: 1/Où s'est- déroulée, l'expansion agricole dans le district de Bao Loc ? 2/ Quel élément de l'utilisation du sol connaît le plus de changement ? 3/ Quel rôle joue les éléments socio-économiques (pression démographique, prix des produits agricoles), physiques (pente du terrain, accessibilité aux ressources en eau et au système routier) dans ce changement? Pour répondre à ces questions, des images satellitaires (prises en 1992 et 1998) et des données auxiliaires (cartes d'utilisation en 1992 et 1998 à l'échelle de 1 : 25 000) ont permis de construire et d'intégrer dans le SIG des cartes d'utilisation du sol au niveau de la commune. Le Modèle Numérique de Terrain (MNT), le système routier, le réseau hydrologique, ont aussi été intégrés à l'aide des logiciels de Mapinfo et Idrisi pour diagnostiquer, évaluer et analyser le changement de l'utilisation du sol en fonction des classes de pentes du terrain, de l'accessibilité aux ressources en eau et au système routier. Les résultats ont indiqué qu'il y a le changement rapide dans l'utilisation du sol à la commune de Loc chan entre 1992 et 1998. Ces changements concernent principalement quelques types d'utilisation du sol : soit les zones de la terre d'habitation (8 à 17%), de caféier (20 à 29%), des arbustes (4 à 6 %) et en particulier, de la forêt (26 à 10 %). Les causes de ces changements sont l'expansion agricole (notamment le remplacement des couvertures forestières primaires par les plantations de caféier) et l'augmentation démographique de la population. Le mobile de l'immigration d'ici est l'attraction des prix de produits agricoles, le prix du café en particulier. Ce projet vise donc à contribuer au suivi de l'environnement dans la Province de Lam Dong. Il permettra d'établir des relations entre les conditions socio-économiques (population et prix des produits agricoles) et les indicateurs physiques. Les résultats obtenus permettront de prendre des décisions dans la planification de la gestion forestière, la localisation des habitats humains et des zones d'activité agricole permanente ou temporaire et, en particulier, dans la détermination des zones favorables au reboisement.||Abstract: In the early stage of the study (1994-1996), results showed a high rate of change in the forest cover in the Lam Dong province. The causes as identified were demographic pressure and agricultural expansion, more specifically the replacement of a specific forest cover by an agro-industrial cover (tea, coffee, mulberry, etc.). In this context, the present study is focused on the integration of satellite data (Landsat TM image) into a GIS for identifying and evaluating the changes in land use at the commune level. The objective is to provide the answer to a certain number of questions such as: (1) Where did agricultural expansion occur in the Bao Loc district? (2) Which element of the land use is undergoing the most change? (3) What role do socio-economic (demographic pressure, agricultural prices) and physical elements (terrain slope, accessibility to water resources and to the road network) play in this change? To answer these questions, satellite images (acquired in 1992 and 1998) and auxiliary data (land use map of 1992 and 1998 at the scale of 1:25 000) were used to construct and integrate into the GIS land use maps at the level of the commune. The Digital Elevation Model (DTM), the road network and the hydrological network were also integrated using the MapInfo and Idridi software."--Résumé abrégé par UM

An Adoption Model of Software as a Service (SaaS) in SMEs

Software as Service (SaaS) model of cloud computing is currently one of the most advanced technology innovations. Due to its scalability and network-based operation, SaaS offers opportunities for small and medium enterprises (SMEs) to take advantage of the latest technology without costly investment on IT infrastructure and expertise. Despite its benefits, SMEs’ adoption of SaaS is not prevalent. In this paper, by synthesizing Diffusion of Innovation theory, Technology-Organization-Environment theory and Protection Motivation theory, we propose a conceptual model which explains adoption factors of SaaS in SMEs. Our proposed model extends focus on protection motivation of SMEs in assessing SaaS adoption risks in addition to technology, organisation, and environment factors