Electrical behavior and Optical Properties of Copper oxide thin Films

In this work the structural, electrical and optical Properties of CuO semiconductor films had been studied, which prepared at three thickness (100, 200 and 500 nm) by spray pyrolysis method at 573K substrate temperatures on glass substrates from 0.2M CuCl2•2H2O dissolved in alcohol. Structural Properties shows that the films have only a polycrystalline CuO phase with preferential orientation in the (111) direction, the dc conductivity shows that all films have two activation energies, Ea1 (0.45-0.66 eV) and Ea2 (0.055-.0185 eV), CuO films have CBH (Correlated Barrier Hopping) mechanism for ac-conductivity. The energy gap between (1.5-1.85 eV)

Cybersecurity Awareness in African Higher Education Institutions: A Case Study of Sudan

The crisis caused by the rapid spread of the coronavirus (COVID-19) has imposed a swift and profound change on teaching and learning methods. Consequently, most higher education institutions around the world, including African higher education institutions, have moved from face-to-face teaching to online learning and teaching, which has made the use of the internet by university students necessary and obligatory regardless of the risks associated with unsafe use. This quick move to online teaching and learning has exposed African universities to a greater risk of cybercrime. This prompted the researchers to investigate the cybersecurity awareness levels among undergraduate students at African higher education institutions based in the case country, Sudan. In an exploratory research approach, a survey was conducted on a convenience sample of 1,200 undergraduate students at six public universities in Sudan. The results show that most undergraduate students in Sudan higher educational institutions have low cybersecurity awareness levels. Further investigation using inferential statistics reveals that male students at the universities in Sudan have slightly higher levels of cybersecurity awareness than female students. Most of the participants believe that cybersecurity should be taught in schools; they are also willing to learn about cybersecurity. In addition, the results showed that students with advanced computer skills significantly differ from students with intermediate or basic computer skills in practicing cybersecurity

A Complexity and Quality Evaluation of Block Based Motion Estimation Algorithms

Motion estimation is a method, by which temporal redundancies are reduced, which is an important aspect of video compression algorithms. In this paper we present a comparison among some of the well-known block based motion estimation algorithms. A performance evaluation of these algorithms is proposed to decide the best algorithm from the point of view of complexity and quality for noise-free video sequences and also for noisy video sequences.

Design and implementation of Threefish cipher algorithm in PNG file

This paper is presenting design and implementation of Threefish block cipher on grayscale images. Despite the fact that Threefish block cipher is one of the best secure algorithms, most studies concerning Threefish have focused on hardware implementation and have not commonly been applied on image encryption due to huge amount of data. The main contribution here was to reduce the time and the amount of data to be encrypted while maintaining encryption performance. This objective was achieved by encrypting just the most significant bits of image pixels. A 256-bit plain text blocks of the Threefish was constructed from 2n most significant bits of the pixels, where 0<n<3. Furthermore, Threefish block cipher was applied when n=3 to analyze the impact of uninvolving some bits in encryption process on the encryption performance. The results indicated that the encryption achieved good encryption quality when n=1, but it might cause some loss in decryption. In contrast, the encryption achieved high encryption quality when n=2, almost as good as the encryption of the whole pixel bits. Furthermore, the encryption time and the amount of data to be encrypted were decreased 50% as n decreased by 1. It was concluded that encrypting half of the pixel bits reduces both time and data, as well as significantly preserves the encryption quality. Finally, although the proposed method passed the statistical analysis, further work is needed to find a method resistant to the differential analysis

An Efficient Sonochemical Synthesis of Novel Schiff’s Bases, Thiazolidine, and Pyrazolidine Incorporating 1,8-Naphthyridine Moiety and Their Cytotoxic Activity against HePG2 Cell Lines

Novel Schiff’s bases 4a–e, 5a, 5b, and 6, thiazolidine 7a–d, and pyrazolidine 8 have been synthesized using the versatile synthon 4-hydroxy-2,7-dimethyl-1,8-naphthyridine 1. Reactions carried out under ultrasound irradiation showed higher rates and yields than those done under silent conditions. The newly synthesized compounds were evaluated for HepG2 cell growth inhibition. The results obtained revealed that the tested compounds possess inhibitory effect on the growth of HepG2 liver cancer cells. The results were compared to doxorubicin as a reference drug (IC50: 0.04). Compounds 4a and 7b showed the highest inhibition activity against the HepG2 cell line (IC50: 0.047 and 0.041 µM, resp.) among all the tested compounds

An HI study of the collisional ring galaxy NGC 922

We present new atomic hydrogen (HI) observations of the collisional ring galaxy NGC 922 obtained using the Australia Telescope Compact Array. Our observations reveal for the first time the vast extent of the HI disc of this galaxy. The HI morphology and kinematics of NGC 922 show that this galaxy is not the product of a simple drop-through interaction, but has a more complex interaction history. The integrated HI flux density of NGC 922 from our observations is 24.7 Jy km s$^{-1}$, which is within the error of the flux value obtained using the $64$-m Parkes radio telescope. This flux density translates to a total HI mass of $1.1*10^{10}$ M$_{\circ}$ and corresponds to an HI to total mass fraction (M$_{HI}$/M$_{tot}$) of approximately $0.11$. The gaseous structures of NGC 922 are more extended to the north and include an HI tail that has a projected physical length of $8$ kpc. Gas warps are also evident in the velocity field of NGC 922 and are more prominent on the approaching and the western side of the disc. In comparison with a large sample of star-forming galaxies in the local Universe, NGC 922 possesses a high gas fraction relative to galaxies with a similar stellar mass of ~$10^{10.4}$ M$_{\circ}$, and exhibits a high specific star formation rate.Comment: 11 pages, 8 figures, published in MNRA

Numerical and experimental investigations on efficient design and performance of hydrokinetic Banki cross flow turbine for rural areas

Micro hydrokinetic energy scheme presents an attractive, environmentally-friendly and efficient electric generation in rural, remote and hilly areas. However, this scheme is yet to be fully discovered, as researchers are still searching for solutions for the main problems of low velocity of current in the open flow channels and low efficiency of hydrokinetic turbines. This research proposes a novel system configuration to capture as much kinetic energy as possible from stream water current. This system, known as bidirectional diffuser augmented (BDA) channel, functions by utilizing dual directed nozzles in the flow and is surrounded by dual cross flow/Banki turbines. It is also important to obtain the efficient design parameters of the turbines to use in the current configuration. The appropriate angle is important in order to guide the flow to touch the blades more perpendicularly to capture as much torque and power as possible. Hence, experimental and numerical investigations have been carried out in this research paper to study the performance characteristics of the CFT configuration applied in BDA system and investigate the effects of blades’ inlet and outlet angles of CFT runners on the internal flow characteristics and efficiency. In this study, four different runners with various inlet and outlet angles of two CFT have been investigated. The CFD results have been validated with the experimental work and proven acceptable with flow pattern and performance characteristics. The results of the current study conclude that the maximum power coefficients (Cp) of 0.612 and 0.473 for lower and upper turbines are recorded for best runner angles of Case 3