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CONTENTS
Volume 3, Number 4, December 2015
 

Abstract
In this article, various higher-order shear deformation theories (HSDTs) are developed for bending and buckling behaviors of nanowires including surface stress effects. The most important assumption used in different proposed beam theories is that the deflection consists of bending and shear components and thus the theories have the potential to be utilized for modeling of the surface stress influences on nanowires problems. Numerical results are illustrated to prove the difference between the response of the nanowires predicted by the classical and non-classical solutions which depends on the magnitudes of the surface elastic constants.

Key Words
surface effects; nanowires; bending; buckling

Address
Djamel Ould Youcef, Abdelhakim Kaci:Laboratoire de Modelisation et Simulation Multi-echelle, Departement de Physique, Faculte des Sciences Exactes, Departement de Physique, Université de Sidi Bel Abbes, Algeria
Mohammed Sid Ahmed Houari: Laboratoire des Structures et Materiaux Avances dans le Genie Civil et Travaux Publics,
Universite de Sidi Bel Abbes, Faculte de Technologie, Département de Genie Civil, Algeria
Abdelouahed Tounsi: Laboratoire de Modelisation et Simulation Multi-echelle, Departement de Physique, Faculte des Sciences Exactes, Departement de Physique, Université de Sidi Bel Abbes, Algeria; Laboratoire des Structures et Materiaux Avances dans le Genie Civil et Travaux Publics,
Universite de Sidi Bel Abbes, Faculte de Technologie, Département de Genie Civil, Algeria; Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Abdelnour Benzair and Houari Heireche: Laboratoire de Modelisation et Simulation Multi-echelle, Departement de Physique, Faculte des Sciences Exactes, Departement de Physique, Université de Sidi Bel Abbes, Algeria

Abstract
The present paper investigate the elastic buckling of chiral double-walled carbon nanotubes (DWCNTs) under axial compression. Using the non-local elasticity theory, Timoshenko beam model has been implemented. According to the governing equations of non-local theory, the analytical solution is derived and the solution for non-local critical buckling loads is obtained. The numerical results show the influence of non-local small-scale coefficient, the vibrational mode number, the chirality of carbon nanotube and aspect ratio of the (DWCNTs) on non-local critical buckling loads of the (DWCNTs). The results indicate the dependence of non-local critical buckling loads on the chirality of single-walled carbon nanotube with increase the non-local small-scale coefficient, the vibrational mode number and aspect ratio of length to diameter.

Key Words
double-walled carbon nanotubes; chirality; buckling; small-scale; non-local elasticity

Address
Awda Chemi, Houari Heireche: Laboratoire de Modelisation et Simulation Multi-echelle, Universite de Sidi Bel Abbes, Algerie
Mohamed Zidour: Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M\'hidi,
22000 Sidi Bel Abbes, Algerie; Université Ibn Khaldoun, BP 78 Zaaroura, 14000 Tiaret, Algerie
Kaddour Rakrak: Laboratoire de Modelisation et Simulation Multi-echelle, Universite de Sidi Bel Abbes, Algerie; Departement de physique, Faculte des Sciences,.Universite Hassiba benbouali, Chlef, Algerie
Abdelmoumen Anis Bousahla: Laboratoire de Modelisation et Simulation Multi-echelle, Universite de Sidi Bel Abbes, Algerie

Abstract
Nanotechnology is considered the most important technological advancement in recent years, and it is utilized in all industries due to its potential applications. Almost all of the industries (food, agriculture, medicine, automotive, information and communication technologies, energy, textile, construction, etc.) reorganize their future in the light of nanotechnological developments. As the most important source of income of countries, the agriculture industry increases the use of nanotechnology products gradually as a solution to the problems encountered. Reducing the use of agricultural inputs (pesticides, herbicides, fertilizers, etc.) by increasing their efficiency utilizing nano-carriers, detecting the environmental conditions and development of the crops in the field simultaneously by making use of nanosensors, reducing the sample volume and the amount of analyte used thanks to nanoarrays, effective treatment of water resources through nano-filters, accelerating the development of crops by using nanoparticles are the prominent nanotechnological applications in the agriculture industry. This review presents information on the benefits of the recent developments in nanotechnology applications in the agriculture industry.

Key Words
agriculture; nanobiotechnology; nano-fertilizers; nano-pesticides; nanobiosensors

Address
Semra Cicek: Department of Nano-Science and Nano-Engineering, Faculty of Engineering, Ataturk University,
Erzurum 25240, Turkey; Department of Agricultural Biotechnology, Ataturk University, Faculty of Agriculture, Erzurum 25240, Turkey
Hayrunnisa Nadaroglu: Department of Nano-Science and Nano-Engineering, Faculty of Engineering, Ataturk University,
Erzurum 25240, Turkey; Department of Food Technology, Erzurum Vocational Training School, Ataturk University,
Erzurum 25240, Turkey

Abstract
The current investigation aims to study performance of geopolymer mortar reinforced with Multiwalled carbon nanotubes upon exposure to 200oC to 1000oC for 2 hrs. MWCNTs are doped into slag Geopolymer mortar matrices in the ratio of 0.0 to 0.4, % by weight of binder. Mortar composed of calcium aluminosilicate to sand (1:2), however, binder composed of 50% air cooled slag and 50% water cooled slag. Various water / binder ratios in the range of 0.114-0.129 used depending on the added MWCNT, while 6 wt., % sodium hydroxide used as an alkali activator. Results illustrate reduction in mechanical strength with temperature except specimens containing 0.1 and 0.2% MWCNT at 200oC, while further increase in temperature leads to decrease in strength values of the resulting geopolymer mortar. Also, decrease in firing shrinkage with MWCNT up to 0.1% at all firing temperatures up to 500oC is observed, however the shrinkage values increase with temperature up to 500oC. Further increase on the firing temperature up to 1000oC results in an increase in the volume due to expansion.

Key Words
MWCNT; geopolymer; mortar; WCS; ACS; thermal stability

Address
H.M. Khater and H.A. Abd El Gawwad: Housing and Building National Research Centre (HBNRC), 87 El-Tahreer St., Dokki, Giza, P.O. Box 1770, Cairo, Egypt


Abstract
In this investigation, ecotoxicity of nano and micro metal oxides, namely silica (SiO2) and alumina (Al2O3), on the growth of green algae (Porphyridium aerugineum Geitler) is discussed. Effects of nano and micro particles on the growth, chlorophyll content and protein content of algae are analysed using standard protocols. Results indicate that SiO2 nano and micro SiO2 particles are non-toxic to P. aerugineum Geitler up to a concentration of 1000 mg/L. In addition, Al2O3 microparticles are less toxic to P. aerugineum Geitler, whereas Al2O3 nanoparticles are found to be highly toxic at 1000 mg/L. Moreover, Al2O3 nanoparticles decrease the growth, chlorophyll content, and protein content of tested algae. In addition, zeta potential and contact angle are also important in enhancing the toxicity of metal oxide nanoparticles in aquatic environment. This study highlights a new insight into toxicity evaluation of nanoparticles on beneficial aquatic organisms such as algae.

Key Words
nano metal oxides; Porphyridium aerugineum Geitler; chlorophyll content; zeta potential; contact angle; protein content

Address
Gopalu Karunakaran: Centre for Nanoscience and Technology, K. S. Rangasamy College of Technology, Tiruchengode-637215, Tamil Nadu, India; Department of Biotechnology, K. S. Rangasamy College of Arts and Science, Tiruchengode-637215, Tamil Nadu, India; Department of Functional Nanosystems and High-Temperature Materials, National University of Science and Technology \"MISiS\", Leninskiy Pr. 4, Moscow, 119049, Russia
Rangaraj Suriyaprabha, Venkatachalam Rajendran: Centre for Nanoscience and Technology, K. S. Rangasamy College of Technology, Tiruchengode-637215, Tamil Nadu, India
Narayanasamy Kannan: Department of Biotechnology, K. S. Rangasamy College of Arts and Science, Tiruchengode-637215, Tamil Nadu, India


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