Study the Effect of Electrical Current on Average Surface Roughness of Borosilicate Glass at EDM Machining and Comparison Using Matlab Program

Machining of electrically non-conducting materials like glass is still a major problem. The principle of electric arc was used to generate high electrical discharge (spark) at high currents to machine non-conducting materials at any hardness. EDM system was build for machining of non-conducting cutting materials such as glass including the use of powder (graphite) mixed for dielectric solution (tap water) by supplied DC current values (200, 250, 300, 350 and 400A). Voltage of (70V) was used to cut 3mm thickness of borosilicate glass (BSG) to obtain the average surface roughness (Ra) of about (0.003-0.012μm). Matlab program has been used to investigate the process control for EDM that could the Ra experimental and theoretical with accuracies of 94.236, 94.034, 96.628 and 92.875% respectively. From the reading of the magnitude of the roughness it was found that differences between the theoretical and experimental values for 3mm thickness of BSG was never exceed (8%)

Experimental Investigations of Hole - EDM to Optimize Electrode Wear through Full Factorial of Design of Experiment

Electrical discharge machining (EDM) is a process where the material removal of the workpiece is achieved through high frequency sparks between the tool (electrode) and the workpiece immersed into the dielectric solution. It is commonly used to produce moulds and dies, to drill small, burr free holes and to make prototypes for the aerospace and electronics markets. In this work, micro-holeswere fabricated on copper alloys by using EDM. The output responses investigated was electrode wear weight (EWW). Full factorial of Design of Experiment (DOE) module in Minitab was used as a principal methodology to examine the effects of current and machining time over output responses. Experimental results indicate that the EWW was mainly affected by current, and can be reduced by increasing the current parameter. Minimum EWW (0.12gm) obtained at 10A

Profound Intraoperative Metabolic Acidosis and Hypotension in a Child Undergoing Multilevel Spinal Fusion

The prone position may cause cardiovascular system depression. Yet, the mechanisms involved and preemptive measures are not well understood (Edgcombe et al. (2008)). During spinal surgery in the prone position, hypotension may occur. Implicated factors include prolonged abdominal compression impeding venous return resulting in increased blood loss, decreased cardiovascular reserve, and the use of total intravenous anesthesia (TIVA) which has been shown to blunt the sympathetic response more than inhalation anesthesia. We present a case of hypotension during spinal surgery with all its challenges. Hypotension and acidosis persisted despite all supporting measures, and only to improve with supine positioning. Differential diagnosis for such an event are discussed. Although abdominal compression may not be obvious before the start of surgery, compressing the spine during surgery may lead to abdominal compression and hypoperfusion to abdominal organs

Is Khat (Catha edulis) chewing a risk factor for periodontal diseases? : a systematic review

Background: Khat (Catha edulis) chewing is a highly prevalent habit in the Arabian Peninsula and East Africa, and has recently spread to Western countries. The association between khat chewing and oral mucosal lesions is well documented in the literature. However, there is no concrete evidence on the association between khat chewing and periodontal disease. The purpose of this systematic review was to analyze the influence of khat chewing on periodontal health. Material and methods: A literature search of PubMed, Scopus and Web of Sciences databases was carried out to identify relevant articles published from 1990 to May 2017. The inclusion criteria were all clinical studies that assessed the relationship between khat chewing and periodontal disease. Results: The search yielded 122 articles, of which 10 were included in this systematic review. Most of the studies exhibited a positive correlation between khat chewing and periodontal disease. Conclusions: Altogether, the analysis of the current evidence reveals that khat chewing is destructive to the periodontium and enhances the risk of periodontal disease progression. However, due to variability of studies, more longitudinal case-controlled studies are highly warranted to establish a causal relation between khat chewing and periodontal disease

Evaluating potential of diatomite as anti clogging agent for porous asphalt mixture

Clogging is a major problem that occurs throughout the service life of porous asphalt due to the open nature of the mixture itself. Diatomite with characteristic of abrasiveness and porous structure seems to have potential in order to remove the clogging materials that mainly consists of soils. This study aims to investigate the effects of diatomite as anti-clogging agent on the permeability rate and strength of porous asphalt. The porous asphalt samples were prepared using Malaysia aggregate gradation and polymer modified bitumen of PG76 was used as the binder. This study focuses on clay as the clogging material at different concentration. A fixed amount of 0.5 g/L diatomite was applied to the porous asphalt samples as an anti-clogging agent prior to clogging cycles. The permeability test and resilient modulus were then conducted at different clogging concentrations (0.5, 1.0, 1.5 g/L) and cycles, with and without diatomite. It was found that samples with diatomite have a higher permeability rate compared to those without any application of diatomite after a few clogging cycles. As the clogging cycles increase, the clogging materials have trapped and filled up the voids in the porous asphalt samples and increase the resilient modulus result

Structural and Functional adaptation of the lingual papillae of the Egyptian fruit bat (Rousettus aegyptiacus): Specific Adaptive feeding Strategies

The current investigation was directed to clarify the correlations between the feeding strategy and lingual structure of the Egyptian fruit bat captured from the Egyptian east desert. The current work depends on twelve adult Egyptian fruit bats that observed grossly and with the help of the stereo, light, and scanning electron microscope. There were three types of the lingual papillae; one mechanical filiform and two gustatory (fungiform and circumvallate). There were seven subtypes of filiform papillae were recognized on the seven lingual regions. There were scanty numbers of fungiform papillae distributed among the filiform papillae on the lingual tip and two lateral parts of apex and body while fungiform papillae completely absent in the median part. There were three circumvallate papillae. The central bulb of circumvallate papillae surrounded by one layer of two segmented circular annular bad. The lingual tip had cornflower-like and diamond-shaped filiform papillae. Histochemical results revealed that the lingual glands were a stronger AB-positive reaction and gave dark blue color, while the reaction for the PAS-stain was negative. Also, the glands exhibited a blue color as an indication of positive AB reactivity with combined AB-PAS staining

Characterization of industrial by-products as asphalt paving material

Most of the recent research is focusing on the utilization of industrial by-products in road construction. The intention is not only to mitigate the problem of waste being dumped to the landfills but to encourage their use as construction material without compromising quality and performance of the road. Steel slag and bottom ash are the industrial by-products generated in large quantity by industry. This study investigates the characteristics of steel slag and bottom ash to be utilized as aggregate in asphalt pavement. Both materials were characterized in terms of physical, chemical and morphological characteristics compared to the conventional granite aggregate. The results revealed that both materials have much potential to be used as aggregate in asphalt mix. The bottom ash was observed weaker in terms of strength, but the steel slag was found much stronger than the granite. The morphological structure of bottom ash and steel slag disclosed that these are made up of porous and rough-edged granular particles with slightly higher water absorption