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Open access

Q. Yousef, M. B. I. Reaz and M. A. M. Ali

This study presents the variations of photoplethysmogram (PPG) morphology with age. PPG measurement is done noninvasively at the index finger on both right and left hands for a sample of erectile dysfunction (ED) subjects. Some parameters are derived from the analysis of PPG contour showed in association with age. The age is found to be an important factor that affects the contour of PPG signals which accelerates the disappearance of PPG’s dicrotic notch and PPG’s inflection point as well. Arterial compliance is found to be degraded with age due to the fall of arterial elasticity. This study approaches the establishment of usefulness of PPG’s contour analysis as an investigator to the changes in the elastic properties of the vascular system, and as a detector of early sub-clinical atherosclerosis.

Open access

B. Ali, S.H. Choi, S.J. Seo, D.Y. Maeng, C.G. Lee, T.S. Kim and K.T. Park

Abstract

The water atomization of iron powder with a composition of Fe-3Cr-0.5Mo (wt.%) at 1600°C and 150 bar creates an oxide layer, which in this study was reduced using a mixture of methane (CH4) and argon (Ar) gas. The lowest oxygen content was achieved with a 100 cc/min flow rate of CH4, but this also resulted in a co-deposition of carbon due to the cracking of CH4. This carbon can be used directly to create high-quality, sinter hardenable steel, thereby eliminating the need for an additional mixing step prior to sintering. An exponential relationship was found to exist between the CH4 gas flow rate and carbon content of the powder, meaning that its composition can be easily controlled to suit a variety of different applications.

Open access

A. Ali, G. Elmowalid, M. Abdel-Glil, T. Sharafeldin, F. Abdallah, S. Mansour, A. Nagy, B. Ahmed and M. Abdelmoneim

Abstract

Epidemic outbreaks of avian influenza (AI) virus H5N1 have been frequently reported in Egypt during the last nine years. Here we investigate the involvement of AI H5N1 in outbreaks of acute respiratory disease that occurred in several commercial chicken farms in Egypt in 2011, and we describe to the pathology caused by the virus in the course of the outbreak.

Twenty-one chicken farms with history of acute respiratory symptoms and high mortalities were screened for AI H5N1. Virus identification was based on hemagglutination inhibition test, and PCR detection and sequencing of the hemagglutinin and neuraminidase genes. Virus distribution was determined by immunohistochemical staining of AI antigens in organs of infected birds. Standard H&E staining was performed for histological examination of affected organs.

Eighty-one % of the examined birds, representing 100% of the screened farms, were positive for AI H5N1 virus. Phylogenetic analysis of the hemagglutinin and neuraminidase genes of the isolated virus reveals its affiliation to clade 2.2.1. Viral antigens were localized in the endothelial cells of the heart, liver, lungs and skin, where pathological lesions including congestion, hemorrhages, multifocal inflammation and necrosis were concurrently observed. According to the pattern of the viral antigen and lesion distribution in the visceral organs, we suggest cardiovascular and circulatory failures as the probable cause of death during these outbreaks. In conclusion, the present study further confirms the epidemic status of AI H5N1 virus in Egypt and reveals the highly pathogenic nature of the local isolates.

Open access

S.H. Choi, B. Ali, K.S. Choi, S.K. Hyun, J.J. Sim, W.J. Choi, W. Joo, J.H. Lim, T.H. Lee, T.S. Kim and K.T. Park

Abstract

Although TiNb2O7 is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb2O7 compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb2O7 phase, the starting materials, TiO2 and Nb2O5 were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.

Open access

Seyyed Mehdi Hosseini Moghaddam, Doost Ali Mojdeh, Babak Samadi and Lutz Volkmann

Abstract

In this paper, we study the signed total domination number in graphs and present new sharp lower and upper bounds for this parameter. For example by making use of the classic theorem of Turán [8], we present a sharp lower bound on Kr+1-free graphs for r ≥ 2. Applying the concept of total limited packing we bound the signed total domination number of G with δ(G) ≥ 3 from above by . Also, we prove that γst(T) ≤ n − 2(s − s′) for any tree T of order n, with s support vertices and s′ support vertices of degree two. Moreover, we characterize all trees attaining this bound.

Open access

Salah Telailia, Lamia Boutabia, Mohamed Dhaya El-Hak Khemis, Ali Elafri and Nawel Djebbari

Abstrat

Recently, Mediterranean coastal lagoons have raised considerable environmental concerns. Long-term studies of seasonal changes in waterbird assemblages are therefore extremely important in terms of ecological relevance and conservation of these sensitive ecosystems. An ornithological survey of four years was carried out in a typical costal wetland (El Mellah lagoon) of Northeastern Algeria. Intra-seasonal comparison of waterbird assemblages (diversity indices) demonstrates clear changes between the wintering and the breeding periods. It seems that the first one was rich in term of species number than the second season (43 against 24). In contrast, the breeding seasons were more equilibrate (high values of Simpson, Shannon and evenness index). Additionally, curves in the diversity/dominance diagram revealed that both wintering and breeding assemblages share the same characteristics of community structure, few dominant species (with intermediate relative abundance) and many rare species with the relative abundance lower than 0.1. Invertebrates (25 species) and piscivorous (11 species) are the most abundant guilds over the four years of study (no significant differences among years have been calculated). The marked decline in bird species diversity recorded in this study (in comparison with previous studies) is mainly due to salinity oscillations (due to aquaculture activities) and may be of concern to wetland managers and it might be useful to provide some guidelines about the characteristics that coastal lagoons have to follow in the construction process to enhance the biodiversity.

Open access

S.H. Choi, B. Ali, S.K. Hyun, J.J. Sim, W.J. Choi, W. Joo, J.H. Lim, Y.J. Lee, T.S. Kim and K.T. Park

Abstract

Combustion synthesis is capable of producing many types of refractory and ceramic materials, as well as metals, with a relatively lower cost and shorter time frame than other solid state synthetic techniques. TiO2 with Mg as reductant were dry mixed and hand compacted into a 60 mm diameter mold and then combusted under an Ar atmosphere. Depending on the reaction parameters (Mg concentration 2 ≤ α ≤ 4), the thermocouples registered temperatures between 1160°C and 1710°C · 3 mol of Mg gave the optimum results with combustion temperature (Tc) and combustion velocity (Uc) values of 1372°C and 0.26 cm/s respectively. Furthermore, this ratio also had the lowest oxygen concentration in this study (0.8 wt%). After combustion, DC plasma treatment was carried out to spheroidize the Ti powder for use in 3D printing. The characterization of the final product was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and N/O analysis.

Open access

Arezou Shafaghat, Golnoosh Manteghi, Ali Keyvanfar, Hasanuddin Bin Lamit, Kei Saito and Dilshan Remaz Ossen

Abstract

Urban climatologists have moved smoothly towards urban geometry meso-scales as obstruction between buildings, streets, and urban environment. Urban climatologists and designers have expressed that urban geometry parameters affect urban microclimate conditions. Improper functioning of the geometry factors, particularly air temperature and wind speed, can increase the harshness of climate change and Urban Heat Island (UHI) defects, which are more critical in coastal cities of tropical regions. In this regard, the current study aimed to identify the impact of each street geometry factor on urban microclimate through a critical literature review. The research determined a total of twenty seven (27) factors within three clusters; 1) geometry factors, 2) meteorological factors, and 3) streetscape factors. The content analysis calculated the Depth of Citation (DoC) which refers to the cumulative importance level of each factor. The content analysis resulted air temperature (Ta) (DoC = 18 out of 28) is the most important street geometry factor that should be extensively considered in urban microclimate studies in coastal cities. In contrast, the factors (such as air pollution and traffic load) have received a minimum Doc (1 out of 28). The research has also analyzed the importance level of clusters through an expert input study using Grounded Group Decision Making (GGDM) method. The results show that meteorological cluster (92 %), streetscape cluster (86 %), and geometry cluster (85 %) have to be respectively implemented in urban microclimate studies in coastal cities. The research states there are new approaches have not yet been touched by urban climatologist affecting urban microclimate; included; surface materials, sea-borne dust and sand, user’s satisfaction, user’s thermal adaptive behavior. These approaches can potentially exacerbate UHI effects in coastal cities, which need further research.