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Search Results: 1 - 10 of 8752 matches for " Sol Space "
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Essin Turhan,Talat K?rpinar
Boletim da Sociedade Paranaense de Matemática , 2013,
Abstract: In this paper, we study general helices in the Sol3. We characterize the general helices in terms of their curvature and torsion. Finally, we find out their explicit parametric equations in the Sol3.
Journal of Science and Arts , 2012,
Abstract: In this paper, we study inextensible flows of b-btangent developable surfaces of biharmonic new type b-bslant helix in the Sol^3 . We obtain partial differential equation for tangent developable surfaces of biharmonic new type b-slant helix in terms of their Bishop curvatures. Finally, we find explicit parametric equations one-parameter family of the b-btangent developable surface of a unit speed non-geodesic biharmonic new b-bslant helix in Sol^3.
Synthesis and Characterization of Triply Doped Nano-Composite Alumina-Phospho- Silicates SiO2-P2O5-Al2O3 with Er3+, Sm3+ and Yb3+ Ions Prepared by Sol Gel Technique in Two Different Forms Thin Film and Monolith  [PDF]
I. K. Battisha, M. A. Salem, Y. Badr, M. Kamal, A. M. S. El Nahrawy
New Journal of Glass and Ceramics (NJGC) , 2016, DOI: 10.4236/njgc.2016.61001
Abstract: Nano-composite monolith and thin film Alumina-Phospho-Silicates (SiO2-P2O5-Al2O3):Ln (Ln = Sm, Er, Yb) glasses activated by triply doped with three different rare earth ions (REIs) (Er3+:Yb3+:Sm3+) were prepared by modified sol-gel process. The composition of the prepared samples was as follow (SiO2:11P2O5:3Al2O3:1.2Er2O3:(1.2 - 3)Yb2O3:(0.7 - 1.3)Sm2O3). Tetra-ethyl-orthosilicate (TEOS), tri-ethyl-phosphate (TEP), erbium nitrate, ytterbium nitrate and samarium nitrate were used as precursor materials, respectively. The structure of the prepared samples was studied using X-ray diffraction (XRD), which revealed that the crystallite sizes of monolith and thin film samples both sintered at 900℃?at constant Sm3+ concentration at 1.3 mol% (SPAE1.2Y1.8S1.3) have the following values 44 and 31 nm, respectively. Transmission Electron Microscopy (TEM) of the same prepared samples was used to confirm the presence of nano-structure phase. The photo-luminescence study will be evaluated for the prepared.

Les sols construits
Christian Sapin et Jean-Jacques Schwien
Bulletin du Centre d’études Médiévales d’Auxerre , 2011, DOI: 10.4000/cem.12050
Abstract: L’archéologie médiévale a su renouveler ces dernières années le domaine traditionnel de la construction, en développant ou assimilant les méthodes de datation (absolue et relative), en explorant de fa on systématique certaines thématiques – les charpentes, les techniques d’échafaudage, les enduits… – et en reprenant même des sources déjà connues – la comptabilité, pour le commerce des matériaux.Le point commun à ces champs renouvelés est pour l’essentiel celui des élévations. Paradoxalement, ...
Synthesis and Structural Characterization of Hydroxyapatite-Wollastonite Biocomposites, Produced by an Alternative Sol-Gel Route  [PDF]
Martín A. Encinas-Romero, Jesús Peralta-Haley, Jesús L. Valenzuela-García, Felipe F. Castillón-Barraza
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2013, DOI: 10.4236/jbnb.2013.44041

Hydroxyapatite is a type of calcium phosphate-based material with great interest for biomedical applications, due to the chemical similarity between this material and the mineral part of human bone. However, synthetic hydroxyapatite is essentially brittle; the practice indicates that the use of hydroxyapatite without additives for implant production is not efficient, due to its low strength parameters. In the present work, biocomposites of hydroxyapatite-wollastonite were synthesized by an alternative sol-gel route, using calcium nitrate and ammonium phosphate as precursors of hydroxyapatite, and high purity natural wollastonite was added in ratios of 20, 50 and 80 percent by weight immersed in aqueous medium. Formation of hydroxyapatite occurs at a relatively low temperature of about 350?C, while the wollastonite remains unreacted. After that, these biocomposites were sintered at 1200?C for 5 h to produce dense materials. The characterization techniques demonstrated the presence of hydroxyapatite and wollastonite as unique phases in all products.

Thermo-Stability of Natural Products Based on Chlorophyll Species Embedded in Silica Xerogel  [PDF]
José Martínez-Mendoza, Erika Espericueta-González, Diana Espericueta González, Gerardo Ortega-Zarzosa, Azdrubal Lobo Guerrero
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.74034
Abstract: This work studied the thermostability and the biostability of chlorophyll species obtained from an extract of spinach leaves embedded in a silica xerogel matrix. The analysis was done by monitoring the photosystem II (PSII) using fluorescence spectroscopy. Samples were prepared using the sol gel method with a molar ratio of ethanol/H2O/TEOS of 4:11.6:1. Then, silica xerogel matrix was loaded with an extract of spinach leaves, obtained in dark conditions. The measurement of the fluorescence spectra was done at selected temperatures to the corresponding non-physiological regimen. Results indicate that the PSII band position remains unchanged when heat treatment temperature increases up 200°C. For temperatures above 100?C, the fluorescence intensity diminishes linearly when the temperature increases. The photosystem II embedded in silica xerogel matrix is decomposed at temperatures above 200°C.
Structural Comportment of Extract of Bougainvillea xbuttiana Flower Incorporated in Silica Xerogel Matrix  [PDF]
José Martínez-Mendoza, Erika Espericueta-González, Diana Espericueta-González, Gerardo Ortega-Zarzosa, Azdrubal Lobo Guerrero
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.76078
Abstract: Measurement of the fluorescence comportment of Bougainvillea xbuttiana flowers embedded in silica xerogels matrix prepared with two different water to tetraethyl-orthosilicate [Si(OC2H5)4] ratio molar of 11 and 5, without heat-treatment, we report the grade of biostability of compound. The structural comportment for the PSI and PSII present in Bougainvillea flower is similar to the structural comportment for these photosystems present in leaves when they are incorporated on inorganic matrix such as silica xerogels. The contribution of the natural pigment of this kind of flower such as betalains which consist of betaxanthins and betacyanins, determines their colors contributed in the range of wavelength from about 550 nm to 660 nm.
The Sustainable Use of Outer Space: Complications and Legal Challenges to the Peaceful Uses and Benefit of Humankind  [PDF]
Mohammad Saiful Islam
Beijing Law Review (BLR) , 2018, DOI: 10.4236/blr.2018.92016
Abstract: All over the world space applications are considered as vital tools for carrying development in respect of social, economic and environment. The major space faring country grows their economy, science, technology, security through the use of space. Predominantly, events for economic growth through space exploration have considered noteworthy in the international arena. An uninterrupted increase of space activities indicates that space law and policies have become significant for a large number of countries. However, increasing the space faring nations, commercialization by the public, private entities and privation of political willingness of influential countries also denote the new concern to the peaceful use of space, maintaining space safety, security and sustainability. The existing legal protection towards the peaceful and sustainable uses of space is not measured satisfactorily well-organized and competent. Particularly, the issue of commercialization of space is not well agreed. The goal of this paper is to examine the shortcomings of present regimes and legal challenges to the sustainable use of space with identifying that there is an urgent necessity for effective and more comprehensive regime not just at the international level, but also at the national level.
Heredity of Lower Separation Axioms on Function Spaces  [PDF]
Njuguna E. Muturi
Advances in Pure Mathematics (APM) , 2014, DOI: 10.4236/apm.2014.43014

The set of continuous functions from topological space Y to topological space Z endowed with a topology forms the function space. For A subset of Y, the set of continuous functions from the space A to the space Z forms the underlying function space with an induced topology. The function space has properties of topological space dependent on the properties of the space Z, such as the T0, T1, T2 and T3 separation axioms. In this paper, we show that the underlying function space inherits the T0, T1, T2 and T3 separation axioms from the function space, and that these separation axioms are hereditary on function spaces.

Social Production of Space: “Lived Space” of Informal Livelihood Operators; the Case of Dares Salaam City Tanzania  [PDF]
Nelly John Babere
Current Urban Studies (CUS) , 2015, DOI: 10.4236/cus.2015.34024
Abstract: This paper critically examines the social production of space for informal livelihood activities. While many progressive scholars have embraced the idea of eviction and harassment of the informal livelihood operators, what these scholars have often left unexplored is how informal operators contribute to the social production of space in urban areas. The first half of this paper focuses on the idea of Lefebvre’s conceptualisation of social production of space and the linkage with the informal livelihood activities. The second section focuses specifically on how social production of space is manifested in the operation of the informal livelihood operators. I argue that informal mode of production of space should be considered to inform how spaces for such activities are produced.
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