COMPUTABILITY IN HOMOGENEOUS STRUCTURES

1972 ◽  
Vol 21 (1) ◽  
pp. 79
Author(s):  
V Aladjev
Keyword(s):  
Homogeneous Structures

Green Route for the Removal of Pb from Aquatic Environment

2020 ◽  
Vol 23 (7) ◽  
pp. 587-598 ◽  
Author(s):  
Ahmed Refaat ◽  
Hanan Elhaes ◽  
Nabila S. Ammar ◽  
Hanan S. Ibrahim ◽  
Medhat Ibrahim
Keyword(s):  
Molecular Modeling ◽  
Sodium Alginate ◽  
Water Hyacinth ◽  
Aquatic Plant ◽  
Cost Effective ◽  
Important Process ◽  
Green Route ◽  
Homogeneous Structures ◽  
Different Sources ◽  
Water Hyacinth Root

Aim and Objective: Wastewater treatment/remediation is a very important process that has a great environmental and economic impact. Therefore, it is crucial to innovate different methods to remove pollutants of different sources from wastewater. This work was conducted in order to study the removal of lead (Pb+2) from wastewater using microspheres of composites of sodium alginate, cellulose and chitosan, as well as using a cost-effective green route through composites of sodium alginate and dried water hyacinth. Materials and Methods: Molecular modeling at B3LYP/6-31g(d,p) was utilized to study sodium alginate, cellulose and chitosan. Sodium alginate was cross-linked with calcium chloride to form microspheres, then both sodium alginate/cellulose and sodium alginate/chitosan were also crosslinked as 50/50 to form microspheres. The roots of the aquatic plant water hyacinth in dry form were added to the cross-linked sodium alginate for up to 70%. SEM and FTIR were employed to study the surface of the prepared microspheres and their structures respectively. Atomic absorption spectroscopy was used to study the levels of Pb. Results: Molecular modeling indicated that the blending of such structures enhances their ability to bind with surrounding molecules owing to their ability to form hydrogen bonds. SEM results indicated that homogeneous structures of cellulose and chitosan are deformed when blended with sodium alginate, and FTIR confirmed the proper formation of the desired blends. Microspheres from sodium alginate showed the ability to remove Pb+2 from wastewater. SEM indicated further deformation in the morphology with the roughness of sodium alginate/water hyacinth microspheres, while FTIR confirmed the uniform matrices of the microspheres. The removal of Pb+2 was enhanced because of the addition of dried water hyacinth's roots. Conclusion: Modeling, experimental and kinetic data highlight sodium alginate/water hyacinth root as a green route to remediate Pb+2 from wastewater.

Binary Homogeneous Structures II

1986 ◽  
Vol s3-52 (3) ◽  
pp. 412-426 ◽  
Author(s):  
A. H. Lachlan
Keyword(s):  
Homogeneous Structures

scholarly journals Stable finitely homogeneous structures

1986 ◽  
Vol 296 (2) ◽  
pp. 815-815 ◽  
Author(s):  
G. Cherlin ◽  
A. H. Lachlan
Keyword(s):  
Homogeneous Structures

scholarly journals The Lattice of Definable Equivalence Relations in Homogeneous $n$-Dimensional Permutation Structures

10.37236/5980 ◽  
2016 ◽  
Vol 23 (4) ◽  
Author(s):  
Samuel Braunfeld
Keyword(s):  
Distributive Lattice ◽  
Equivalence Relations ◽  
Electronic Journal ◽  
Finite Distributive Lattice ◽  
Linear Orders ◽  
Finite Dimensional ◽  
Homogeneous Structures ◽  
Special Case

In Homogeneous permutations, Peter Cameron [Electronic Journal of Combinatorics 2002] classified the homogeneous permutations (homogeneous structures with 2 linear orders), and posed the problem of classifying the homogeneous $n$-dimensional permutation structures (homogeneous structures with $n$ linear orders) for all finite $n$. We prove here that the lattice of $\emptyset$-definable equivalence relations in such a structure can be any finite distributive lattice, providing many new imprimitive examples of homogeneous finite dimensional permutation structures. We conjecture that the distributivity of the lattice of $\emptyset$-definable equivalence relations is necessary, and prove this under the assumption that the reduct of the structure to the language of $\emptyset$-definable equivalence relations is homogeneous. Finally, we conjecture a classification of the primitive examples, and confirm this in the special case where all minimal forbidden structures have order 2. 

Criterion of Mechanical Instability in Inhomogeneous Atomic System

2005 ◽  
Vol 482 ◽  
pp. 127-130 ◽  
Author(s):  
Yoshitaka Umeno ◽  
Takayuki Kitamura
Keyword(s):  
Mechanical Stability ◽  
Atomic System ◽  
Instability Criterion ◽  
Fundamental Issue ◽  
Mechanical Instability ◽  
Atomic Systems ◽  
Uniform Deformation ◽  
Atomic Structures ◽  
Homogeneous Structures ◽  
Deformation Modes

The mechanical stability of a material is a fundamental issue in strength of atomic systems. Although the criterion of the mechanical stability of homogeneous structures such as perfect crystals have been successfully investigated so far, the criterion has not been able to be precisely evaluated in the cases of non-uniform deformations or bodies of inhomogeneous atomic structures. Now we present an instability criterion of an arbitrary atomic structure based on the energy balance of the whole system. This method gives the mathematically rigorous condition for the onset of an unstable deformation in any inhomogeneous atomic system. Furthermore, the method can be applied to any type of potential field, which means that ab initio evaluations of the mechanical instability of inhomogeneous structure under non-uniform deformation will be possible. The validity of the method is clarified by the application to tension of a cracked body. The onsets of unstable deformations and their deformation modes are precisely evaluated by the method.

scholarly journals Nonlinearity Measurements Using Alternating Current

1978 ◽  
Vol 5 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Vladimír Ryšánek ◽  
Carlo Corsi ◽  
Arnaldo d'Amico
Keyword(s):  
Frequency Band ◽  
Measurement Technique ◽  
Alternating Current ◽  
Noise Measurement ◽  
Wide Frequency Band ◽  
Semiconductor Structures ◽  
Different Types ◽  
Homogeneous Structures ◽  
Lock In

The nonlinearity measurement technique described uses an adapted conventional lock-in-amplifier. This technique enables us to measure small nonlinearities over a wide frequency band and is more sensitive than the 1/f noise measurement used to detect non-homogeneous structures in conductors, resistors and semiconductor components. Results illustrating uses of this method are presented for different types of resistor and semiconductor structures.

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