The unique characteristics of the laser beam compared to the normal light i.e. its directionality, monochromatcity, and brightness make it a very important tool in the surface engineering. The concentrated heat in the laser beam can precisely directed toward the processed region on the surface. The laser beam power, size, and scanning velocity are easily controlled during the different processing methods. Laser surface modifications of metallic materials, such as laser surface melting, laser surface alloying, and laser cladding are some of the most important methods to improve the mechanical properties of the processed layer on the surface. A pulsed Nd-YAG laser surface melted specimens of low carbon steel with a maximum power of 90W at different processing parameters. The rapid melt and resolidification of the treated layer produced a refinement in the microstructure. The original microstructure of this steel (Ferrite + Pearlite) has been transformed to new phases of martensitic and bainitic structures. The melted layer consists of the melted pool, the heat affected zone, and the substrate. The maximum hardness of the laser melted layer is more than 400 HV.

Key words:Laser surface Melting, Carbon steel, Microstructure, Microhardness

الملخص

Synthesizing silver nanoparticles (AgNPs) from extracts of various plant parts

and of agricultural waste is strongly affected by pH. These green synthesis

methods cconsidered simple, cost effective, ecofriendly, and biologically

effective. This brief review aimed to survey the role of pH in the green

synthesis of AgNPs using those media, with a focus on its effect on AgNPs

morphology and size. This review article revealed that the alkaline pH (9 -

10) is the optimum condition for synthesizing more stable and tiny uniform

AgNPs. In addition, according to the reviewed articles, the spherical shape is

the most dominant shape of these articles in the basic medium and the size of

these particles decreases at elevated pH values and ranged from 5-40 nm

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Harmonic function is one of an important branches of complex analysis. The first study of complex valued, harmonic mappings defined on a domain D was given by ClunIe and SheIl-Small [1]. Harmonic functions have been studied by different researchers such as Silverman [6]. In the present paper, a new class of harmonic univalent functions will be introduced. Various properties of functions belong to this class which include coefficient bounds, growth bounds, a closure property, extreme points, neighborhood and a convex combination will be obtained.

Synthesizing silver nanoparticles (AgNPs) from extracts of various plant parts

and of agricultural waste is strongly affected by pH. These green synthesis

methods cconsidered simple, cost effective, ecofriendly, and biologically

effective. This brief review aimed to survey the role of pH in the green

synthesis of AgNPs using those media, with a focus on its effect on AgNPs

morphology and size. This review article revealed that the alkaline pH (9 -

10) is the optimum condition for synthesizing more stable and tiny uniform

AgNPs. In addition, according to the reviewed articles, the spherical shape is

the most dominant shape of these articles in the basic medium and the size of

these particles decreases at elevated pH values and ranged from 5-40 nm.

Hill Cipher is one of the symmetric key algorithms in cryptography, we discussed Encryption

and decryption for the alphabet Arabic by Hill cipher encryption and descriptions using the

invertible matrix as a key. In this study, we introduce a new method on the Hill Cipher for the

alphabet Arabic using a rectangular matrix as a key.