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 Advances in Natural Sciences: Nanoscience and Nanotechnology      [16 followers]  Follow      Open Access journal    ISSN (Print) 2043-6254 - ISSN (Online) 2043-6262    Published by Institute of Physics (IOP)  [56 journals]
• Making germanium, an indirect band gap semiconductor, suitable for
light-emitting devices

• Authors: Thi Kim Phuong Luong; Vinh Le Thanh, Abdelhamid Ghrib, Moustafa El Kurdi Philippe Boucaud
First page: 015013
Abstract: Germanium (Ge) is a group-IV indirect band gap semiconductor but the difference between its direct and indirect band gap is only 140 meV. It has been shown that when Ge is subjected to a tensile strain and a heavy n -doping level, room-temperature photoluminescence (PL) can be greatly enhanced. Among these two factors, achieving a heavy n -doping level in Ge (i.e., electron concentrations higher than 1 × 10 19 cm −3 ) is a challenge since the solubility of most group-V elements (P, As, Sb) in Ge is very low. We report here Ge growth on silicon substrates using molecular beam epitaxial (MBE) technique. To enhance the n -doping level in Ge, a specific n -doping process based on the decomposition of the GaP compound has been implemented. The GaP decomposition allows producing P 2 molecules, which have a higher sticking coefficient than that of P 4 molecules. We show that phosphorus doping at low substrate temperatures fo...
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2015-01-06T00:00:00Z
Issue No: Vol. 6, No. 1 (2015)

• Quantum theory of plasmons at metallic spherical surface

• Authors: Van Hieu Nguyen; Bich Ha Nguyen Van Thanh Ngo
First page: 015014
Abstract: In the present work the functional integral technique was applied to the study of the collective excitations of electron gas at a spherical surface. The quanta of these collective excitations are the surface plasmons. Starting from the fundamental principles of the quantum theory, the generating functionals of the many-electron system in a spherical surface were introduced in two different cases, when the electron–electron Coulomb interaction is absent or is present. By means of the Hubbard–Stratonovich transformation, the generating functional of the electron system in the presence of the electron–electron interaction was transformed into that of a scalar field, the effective action of this scalar field was established and the plasmon field was introduced. Then the expression of the Hamiltonian of the quantum field of plasmons was derived and the system of algebraic equations determining the energies of plasmons was established.
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2015-01-06T00:00:00Z
Issue No: Vol. 6, No. 1 (2015)

• Synthesis and application of quantum dots-based biosensor

• Authors: Ngoc Hai Nguyen; Thi Giang Duong, Van Nong Hoang, Nam Thang Pham, Tran Cao Dao Thu Nga Pham
First page: 015015
Abstract: Trichlorfon (TF) is one of the organophosphorus pesticides used widely in agriculture. The content of this paper includes the exploitation of dominant optical properties of the quantum dots consisting of a core and multilayer shell CdSe/ZnSe/ZnS (QD). A biosensor was fabricated on the basis of this QD for rapidly detecting the residues of trichlofon pesticide with concentrations of 0.01 ppm to 5 ppm. The measurements were carried out to examine the morphology of the QD structure and fluorescent properties such as transmission electron microscopy, x-ray diffraction, absorption spectroscopy and fluorescence spectroscopy. The linking mechanism among biological agents and the specificity of the acetylcholinesterase enzymes in hydrolysis reaction of acetylthiolcholine was applied to create the changes in surroundings, affecting the fluorescence of the QD. In particular, the mechanism of bioluminescence resonance energy transfer (BRET) is discussed to clearly explain the recombination ...
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2015-01-06T00:00:00Z
Issue No: Vol. 6, No. 1 (2015)

• Air purification equipment combining a filter coated by silver
nanoparticles with a nano-TiO 2 photocatalyst for use in hospitals

• Authors: Thanh Son Le; Trong Hien Dao, Dinh Cuong Nguyen, Hoai Chau Nguyen I L Balikhin
First page: 015016
Abstract: X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed that TiO 2 particles synthesized by a sol–gel procedure exhibited uniform size about 16–20 nm. This nanopowder was deposited on a porous quartz tube ( D = 74 mm, L = 418 mm, deposit density ∼16.4 mg cm −2 ) through an intermediate adhesive polymethylmethacrylate layer to manufacture a photocatalytic filter tube. A polypropylene pre-filter was coated with a nanosilver layer (particle size ∼20 nm) prepared by aqueous molecular solution method. An air cleaner of 250 m 3 h −1 capacity equipped with this pre-filter, an electrostatic air filter, 4 photocatalytic filter tubes and 4 UV-A lamps (36 W) presented the high degradation ability for certain volatile organic compounds (VOCs), bacteria and fungi. The VOCs degradation performances of the equipment with respect to divers compounds are different: in a 10 m 3 box, 91.6% of butanol w...
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2015-01-06T00:00:00Z
Issue No: Vol. 6, No. 1 (2015)

• Evolution of magnetism in UCoGe and UCoAl with Ru doping

• Authors: Michal Vališka; Petr Opletal, Jiří Pospíšil, Jan Prokleška Vladimír Sechovský
First page: 015017
Abstract: Intriguing magnetic properties of the UCo 1− x Ru x Ge and UCo 1− x Ru x Al pseudoternary systems studied on single crystals are presented and discussed in terms of anisotropic 5f-ligand hybridization as the principal driving mechanism. Ferromagnetism of the ferromagnetic superconductor UCoGe is initially stabilized by Ru substitutions for Co (superconductivity suppressed already for x  > 0.01) providing maximum Curie temperature ( T C ), spontaneous magnetic moment ( μ s ) and magnetic entropy ( S mag ) for 10% Ru. Further increasing Ru concentration leads to gradual suppression of these parameters towards a ferromagnetic quantum critical point (FM QCP) at ≈0.31. Non-Fermi liquid scaling of specific heat and electrical resistivity is observed in the vicinity of FM QCP. The itinerant electron metamagnet UCoAl is transformed to a ferromagnet by only 0.5% Ru substitut...
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2015-01-14T00:00:00Z
Issue No: Vol. 6, No. 1 (2015)

• Comparison of some morphological and absorption properties of the
nanoparticles Au/TiO 2 embedded films prepared by different
technologies on the substrates for application in the plasmonic
solar cell

• Authors: Khac An Dao; Thi Thuy Nguyen, Thi Mai Huong Nguyen Duy Thien Nguyen
First page: 015018
Abstract: The nanoparticle Au/TiO 2 embedded system plays a very important role in the plasmonic solar cell. The features of the nanoparticle embedded system will determine light enhancement, light absorption, scattering and localized surface plasmon resonance (LSPR), aiming to enhance the efficiency of the plasmatic solar cell. The characterizations of nanoparticles Au/TiO 2 embedded system consist of many parameters: the sizes of nanoparticles (Au, TiO 2 ), the weight ratio of Au to TiO 2 , the thickness of the single layer or multilayer of Au/TiO 2 , the arrangements of Au and TiO 2 nanoparticles in integrated-matrix system, the light absorption, scattering and LSPR capacities of the Au/TiO 2 system. These parameters, however, depend on the technological conditions, the structure of plasmonic solar cell as well as the used substrate materials. This paper presents some technological developments for nanoparticles Au/TiO
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2015-01-14T00:00:00Z
Issue No: Vol. 6, No. 1 (2015)

• Nanoparticles: synthesis and applications in life science and
environmental technology

• Authors: Hoang Luong Nguyen; Hoang Nam Nguyen, Hoang Hai Nguyen, Manh Quynh Luu Minh Hieu Nguyen
First page: 015008
Abstract: This work focuses on the synthesis, functionalization, and application of gold and silver nanoparticles, magnetic nanoparticles Fe 3 O 4 , combination of 4-ATP-coated silver nanoparticles and Fe 3 O 4 nanoparticles. The synthesis methods such as chemical reduction, seeding, coprecipitation,and inverse microemulsion will be outlined. Silica- and amino-coated nanoparticles are suitable for several applications in biomedicine and the environment. The applications of the prepared nanoparticles for early detection of breast cancer cells, basal cell carcinoma, antibacterial test, arsenic removal from water, Herpes DNA separation, CD4 + cell separation and isolation of DNA of Hepatitis virus type B (HBV) and Epstein–Barr virus (EBV) are discussed. Finally, some promising perspectives will be pointed out.
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2014-12-31T00:00:00Z
Issue No: Vol. 6, No. 1 (2014)

• Boron difluoride complexes of 2′-hydroxychalcones and curcuminoids
as fluorescent dyes for photonic applications

• Authors: Anthony D’Aléo; Abdellah Felouat Frédéric Fages
First page: 015009
Abstract: The field of fluorescent boron complexes has witnessed tremendous developments in recent years. In that context, we have investigated two series of boron difluoride complexes based on 2′-hydroxychalcone and curcuminoid ligands that represent naturally occurring pigment structures. The dyes display significantly large Stokes shift values, indicating that an ICT state is involved as lower-energy state in the singlet manifold. Remarkably they are also fluorescent in the solid-state, with emission wavelengths usually in the visible and mainly in the near infrared (NIR). It is especially intriguing that those dyes experience strong π -interactions in the crystal phase. We have observed that the formation of those highly stacked structures was not detrimental to solid-state emission and could even be exploited for the generation of efficient NIR emitters. For example, the boron complexes of curcuminoid ligands can be used to generate NIR fluorescent organic nanoparticles with lar...
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2014-12-31T00:00:00Z
Issue No: Vol. 6, No. 1 (2014)

• Charge transport in dye-sensitized solar cell

• Authors: Masatoshi Yanagida
First page: 015010
Abstract: The effect of charge transport on the photovoltaic properties of dye-sensitized solar cells (DSCs) was investigated by the experimental results and the ion transport. The short current photocurrent density ( J sc ) is determined by the electron transport in porous TiO 2 when the diffusion limited current ( J dif ) due to the ##IMG## [http://ej.iop.org/images/2043-6262/6/1/015010/ansn506259ieqn1.gif] {${{{\rm I}}_{3}}^{-}$} transport is larger than the photo-generated electron flux ( J g ) estimated from the light harvesting efficiency of dye-sensitized porous TiO 2 and the solar spectrum. However, the J sc value is determined by the ion transport in the electrolyte solution at J dif
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2014-12-31T00:00:00Z
Issue No: Vol. 6, No. 1 (2014)

• The impact of graphene oxide particles on viscosity stabilization for
diluted polymer solutions using in enhanced oil recovery at HTHP
offshore reservoirs

• Authors: Ba Dung Nguyen; Trung Kien Ngo, Truong Han Bui, Duy Khanh Pham, Xuan Loc Dinh Phuong Tung Nguyen
First page: 015012
Abstract: Over 60% of the original oil in a place (OOIP) is retained in a reservoir after conventional methods have been exploited. Application of enhanced oil recovery (EOR) technology gives an additional chance to get out possibly about 20% more oil from the reservoir. The use of water-soluble polymers improves the water–oil mobility ratio, therefore, the displacement efficiency increased, and leads to enhanced oil recovery. High-molecular-weight polyacrylamide group is widely and successfully used in EOR. But no commercial polymer composition can be used in conditions of high temperature and hardness brine offshore reservoirs yet. To avoid the time consumption and high expense for selection and synthesis of the appropriate-structural polymer for EOR application, we attempt to find additives to enhance the thermal stability of polymer solutions. In this paper, we report the results of improved viscosity stability of diluted polymer/seawater solutions aged at reservoir conditions for 31da...
Citation: Advances in Natural Sciences: Nanoscience and Nanotechnology
PubDate: 2014-12-31T00:00:00Z
Issue No: Vol. 6, No. 1 (2014)

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