nitriding is a common method for improving the hardness , mechanical properties, wear and corrosion resistance of metals. Laser nitriding of metals is an efficient process, where the irradiation of surfaces in nitrogen atmosphere leads to the fast take-up of nitrogen in the irradiated surfaces. In this paper laser surface nitriding of carbon steel carried out by melting the surface of substrate using high power CW CO2 laser with nitrogen as shrouding environment. Laser tracks were arranged as single tracks with the use of various laser powers ranging from 0.8kW to 2.0 KW , and laser scanning rates from 120mm/min to 200 mm/min. The influence of laser beam power and laser scanning rates on the microstructure and hardness profiles analysed. The laser nitride layer studied using optical microscope, and scanning electron microscope. The laser surface nitriding of carbon steel led to refinement in the microstructure and the diffusion of nitrogen caused the formation of iron nitrides on the surface. The micro hardness of the nitride surface improved to a maximum of 400HV in the present set of laser processing conditions as compared to 150HV of as received substrate as a result of the appearance of marten site in the melted pool and heat effect zon

This paper presents a new high-capacity algorithm for audio watermarking for the purpose of embedding a watermark audio signal into an original audio signal. This algorithm uses DCT (discrete cosine transform) in combination with SVD (singular value decomposition), DWT (discrete wavelet transform), and CZT (chirp ztransform). For the purpose of ensuring high levels of imperceptibility and robustness, a low-frequency sub band of 1-level DWT is selected to embed the watermark, followed by DCT, CZT, and SVD. As a result, the proposed algorithm achieves a high capacity of 352800 bits per second while a good quality audio signal is maintained (having an objective difference grade of more than-0.04). It also provides high imperceptibility (a signal to noise ratio of more than 58 dB) and it is extremely resistant to common audio attacks, including requantizing, resampling, additive white Gaussian noise or AWGN, MP3 compression, and low-pass filtering. The proposed algorithm presents much better compared to the audio watermarking algorithms already existent.

Prosopis farcta (Banks & Sol.) J. F. Macbr. has been reported for the first time from Libya. This species is native in Asia. Flowering specimens of Prosopis farcta collected from Sokna Region about 650 Km south-east Tripoli. It is presented with updated nomenclature, taxonomic description, geographical distribution, place of occurrence in Libya, and field colored photographs are also provided. The voucher specimens were deposited in the Herbarium of Botany Department (ULT), University of , Tripoli, Libya.

In this paper, the discrete–time periodic static output feedback control design problem is considered. A

hybrid conjugate gradient methods are analyzed and studied to tackle an equivalent optimization problem of this

optimal control problem. Finally, the proposed algorithms are tested numerically through several test problems

from the benchmark collection.

A novel non-blind audio watermarking algorithm, using chirp z-transform in combination with discrete wavelet transform and singular value decomposition, is presented in this paper. In the proposed method, a watermark audio signal (about 13 seconds in length) is hidden into an original audio signal (about 51 seconds in length) by applying discrete wavelet transform, chirp z-transform, and singular value decomposition. The effectiveness of the proposed algorithm has been tested using signal-to-noise ratio, objective difference grade (ODG), and normalised cross- correlation of watermarked audio signal under various common audio attacks. Experimental results demonstrate that the algorithm has a high capacity (352.8 kbps), without significant perceptual distortion (ODG > -0.29) and provides good robustness against common audio attacks, including: re-sampling, echo addition, MP3 compression, additive white Gaussian noise, re- quantisation, cutting, and low-pass filtering. This algorithm has a high capacity and excellent audio quality compared with other audio watermarking algorithms.

Biosynthesis of the metallic nanoparticle is gaining importance because it’s a single-step process, nontoxic, environmentally acceptable, and easily scaled up. The present study investigated the biosynthesis of silver nanoparticles (AgNPs) via reacting olive wastewater filtrate (OWF) with silver nitrate, and the formation of AgNPs was confirmed by a color change of the reaction mixture and visible spectrophotometry. Additionally, the influence of pH, reaction time, AgNO₃ concentration, temperature, and OWF volume on the proposed method was investigated. It was found that with increasing the previously mentioned parameters, the formation of the AgNPs was increased under the experimental conditions. The results showed that OWF represented a promising material for the biosynthesis of AgNPs.      

A convenient method of preparing ultrafine polystyrene latex nano-particles with chlorine groups on the surface is developed. Polystyrene latexes in the size range 50–400 nm were prepared via emulsion polymerization, using sodium dodecyl sulfate (SDS) as surfactant. The poly styrene with chlorine groups on the surface will be fine to use as organic filler to modify rubber. Transmission electron microscopy (TEM) was used to observe the morphology of silicon dioxide and functionalized polystyrene nanoparticles. The nature of bonding between the polymer and the reactive groups on the filler surfaces was analyzed using Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) was employed to examine the filler surface.

ABSTRACT

Natural polymers with improved structure have been securing increasing value in the industry as they

are abundant, cheap, and biodegradable. Graft copolymerization is one of the effective ways to

enhance the properties of natural polymers. Starch based graft copolymers are becoming increasingly

important due to their remarkable adhesion, high water absorbency, and biodegradability. Methyl

methacrylate (MMA) grafted onto starch by using the ceric ammonium nitrate (CAN) as a redox

initiator in the presence of nitric acid in aqueous medium to form grafted copolymer (Starch-g-

PMMA) was investigated. The grafting reaction was carried out under stream of nitrogen gas. The

impact of different reaction parameters to achieve the highest percent grafting (%G) has been studied

by determining the initiator concentration, monomer concentration, time (hours), nitric acid

concentration, and polymerization temperature. The % G was found to be 97%. Evidence of grafting

was characterized and confirmed by Fourier transform infrared spectroscopy (FTIR). The peaks at

1736.70 cm-1 and 3449.78 cm-1 indicates that MMA has been successfully grafted to starch. %G was

found to be decreased at higher than 70°C, after 2 hours of reaction time, with an increase of MMA

monomer concentration, initiator concentration, and with HNO3 concentration. The highest percent

grafting was obtained at the parameters of 1 g starch, 70°C, 2 hours, 2 mmol CAN, 140 mmol MMA

and 0.4 mmol HNO3