A base-line study of the wear of burs used for chairside milling of ceramic crowns of different hardness: effect on internal fit and surface roughness

INTRODUCTION: Wear of milling burs may affect the internal fit and surface roughness of the milled crown. AIM: To assess the wear of diamond and tungsten carbide (TC) burs from milling ceramic materials and the effect on internal fit and surface roughness. METHODS: Thirty crowns of each of the two materials were milled from the same standard preparation. Diamond burs were used for a feldspathic ceramic and TC burs for zirconia. Before and after the 10th, 20th and 30th milling, diamond particle loss was counted and cutting blade changes of the TC burs measured. Internal fit was measured using a silicone replica technique and surface roughness by 3D laser microscope. RESULTS: An average 26% loss of diamond particles occurred after 30 crowns, resulting in a 6% decrease in internal luting space and a 21% decrease in surface roughness. Wear of the TC burs resulted in a 13% decrease in the luting space, and a 16% increase in surface roughness. CONCLUSION: The wear of milling burs reduces the luting space, and the milling parameters must be adjusted to compensate for this. Surface roughness is affected by bur type: with diamond burs it decreased, and increased with TC burs

Diabetes, coronary artery disease and erectile dysfunction doppler study

ObjectivesTo assess the role of measuring cavernosal artery blood flow as a screening tool for ischemic heart disease in patients with erectile dysfunction (ED).MethodsA total of 303 male patients with ED were enrolled in this study. Patients were interviewed for ED using the International Index of Erectile Function. The penile vasculature was assessed using color Doppler ultrasonography and the Digital Inflection Rigidometer. All patients were referred to a cardiologist for evaluation of ischemic heart disease (IHD). All patients underwent routine laboratory investigations, plus total testosterone and prolactin assessments.ResultsSeventy-six percent of the patients had organic causes of ED. Of the 303 patients, 31.4% had different degrees of IHD. A statistically significant association was found between the presence of IHD and arteriogenic causes of ED, a poor response to intracorporal injection, poor rigidity in the Digital Inflection Rigidometer, and low peak systolic velocity (PSV) in the cavernosal arteries (P<0.05 for each). No statistically significant association was found between the presence of IHD and increasing end-diastolic velocity values or decreasing resistive index in the cavernosal arteries (P<0.05 for each). A statistically significant association was found between a higher grade of IHD and a decreasing PSV value (P<0.05).ConclusionsThe results of this study established that a reduced PSV of the cavernous artery is associated with IHD. Determining the PSV could be a reliable screening tool for the detection of IHD in patients with ED

Epidemiological Insights of Foot and Mouth Disease Virus Infection among Cattle and Buffaloes in Sharkia Governorate, Egypt

Foot-and-mouth disease (FMD) is endemic in Egypt and in most parts of Africa causing huge economic losses. Control of FMD using vaccination requires information on the occurrence of various FMDV serotypes. This study aimed to determine the prevalence of FMDV serotypes in Sharkia Governorate, Egypt. A total number of 643 different samples, within ten different localities, were collected from both cattle and buffaloes (n = 283) of different, age, sex, immune status against FMD, and health status. Field samples (n = 360) have been screened for FMDV by RT-PCR using universal primers and were further subtyped using serotype-specific primers. Additionally, serum samples (n = 283) have been analyzed by applying FMDV serotype-specific antibody ELISA. The RT-PCR screening revealed that a total number of 39/283 (13.8%), 61/283 (21.6%) and 17/38 (44.7%) animals were positive for FMDV serotype O, A and SAT2, respectively. While, by ELISA, neutralizing antibodies directed against FMDV serotype O, A, and SAT2, were found in 177/283 (62.5%), 171/283 (60.4%) and 27/38 (71.1%) serum samples, respectively. These results indicated the endemic status of the FMDV serotypes O, A and SAT2 in Sharkia Governorate despite routine FMD vaccination programs. Although many variations of disease prevalence were recorded between animals of different, age, sex and immune and health status but it was obvious that FMD was more prominent and prevalent in buffaloes (47.1%) than in cattle (34.1%). Therefore, control efforts should focus on reducing the circulation of FMDV among susceptible livestock with special attention towards water buffaloes. Continuous surveillance, at molecular and immunological levels, of FMDV serotypes is needed for the effectiveness of any adopted control strategy targeting FMD including vaccination

IMPACT OF LARGE PENETRATION OF WIND ENERGY ON THE PERFORMANCE OF ELECTRIC POWER SYSTEMS

Wind energy represents one of the most important renewable energy resources that can support electrical power systems. Behaviour of wind turbines following contingencies may deteriorate system stability. This requires an extensive analysis of the possible effect of wind energy on the entire power system performance. This paper investigates the effect of wind energy on power system dynamic response. This is achieved by replacing conventional generators gradually by wind turbine (WT). Also, the optimal location of WT has been determined by checking influence on steady state operation. In addition, the effect on total fuel cost is considered to determine the optimal location of WT. The IEEE 30-bus system is used during the study. The results indicate that the system stability is enhanced in most cases with integrating wind energy into power system. The results can provide a scope for future planning and expansion in electric power systems

An investigation into solid waste problem in the Egyptian construction industry: A mini-review

Solid waste management (SWM) is one of the most critical global challenges nowadays. It has a severe negative effect on the triple bottom line of sustainability. Construction and demolition waste (CDW) contributes about 50% of the total global annual generated SW. In the particular case of the Middle East and North Africa (MENA) region including Egypt, the SW problem has become a major challenge, and the need to find sustainable solutions is overwhelming. However, the region faces several challenges that hinder the development of an effective and efficient SWM system. This has resulted in the predominance of unsustainable SWM practices such as indiscriminate disposals. The aim of this paper is to investigate the escalating problem of SW in the MENA region, while focusing on CDW in Egypt as a part of the total generated SW, by reviewing the most recent research papers, and technical and governmental reports on the SW problem. The main challenges towards effective and efficient SWM systems and recommendations for improvement are gathered in this study based on the explored literature. Findings from this study are expected to be beneficial to local and central governments, academics, construction industry practitioners, and policymakers contending with the problems of SW in the MENA region and especially CDW in Egypt

The Impact of Aspect Ratio, Characteristic Strength and Compression Rebars on the Shear Capacity of Shallow RC Beams

This paper investigates the impact of the aspect ratio, the characteristics strength of the concrete, and the compression steel ratio on the shear capacity of wide-shallow beams. An experimental program consists of seven specimens, including a control specimen, all tested under a three-point load test. Three specimens were considered for each parameter (the control specimen was included in all three variables). The experimental results were compared to the theoretical values of six different codes of practice; they were also analyzed to determine the ductility, stiffness, and dissipated energy of each specimen. The results indicated that the shear reinforcement was fully functioning until it yielded, with a minimum contribution of 55% of the total shear capacity of the specimens. The aspect ratio and the characteristic strength had a notable impact on the shear capacity of the specimens, while the compression steel ratio had a minor effect on the shear capacity, but it improved the stiffness and the ductility of the beams. Theoretical concrete shear strengths from design codes ranged between 77 and 163% of the experimental values; EN-1992 was the closest code to the experimental results. A comparison between the experimental results and predicted values using GP and EPR methods from previous research showed accuracies of 72% and 81%, respectively. Doi: 10.28991/CEJ-2023-09-09-012 Full Text: PD

Copper(II)-oxaloyldihydrazone complexes: Physico-chemical studies: Energy band gap and inhibition evaluation of free oxaloyldihydrazones toward the corrosion of copper metal in acidic medium

AbstractA series of oxaloyldihydrazone ligands were prepared essentially by the conventional condensation reaction between oxaloyldihydrazide and different aldehydes e.g., salicylaldehyde, 2-hydroxy-1-naphthaldehyde, 2-hydroxyacetophenone and 2-methoxybenzaldehyde in 1:2M ratio. The synthesized compounds were purified to give bis(salicylaldehyde)oxaloyldihydrazone (L1), bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (L2), bis(2-hydroxyacetophenone)oxaloyldihydrazone (L3) and bis(2-methoxybenzaldehyde)oxaloyldihydrazone (L4). All the oxaloyldihydrazones (L1–L4) and their relevant solid copper(II) complexes have been isolated and characterized by various physicochemical techniques. The identity of the synthesized compounds has been ascertained on the basis of elemental analyses, spectral (UV–Vis, IR, ESR, mass, 1H NMR), magnetism and thermal (TG) measurements. The dihydrazones coordinate to the metal center forming binuclear complexes. Upon chelation, the metal center can form a trigonal distorted octahedral structure with L1 and pseudo tetrahedral configuration with L2 & L3 & L4. The optical band gap energy for all compounds underlies the range of semiconductor materials. The investigated ligands were assayed for their corrosion inhibitive and adsorptive properties on copper surface in 1M HCl solution using weight loss technique. The results pointed out that, the ligands have a plausible inhibition toward the corrosion of copper specimen. The adsorption reaction on copper surface was found to be spontaneous first order and agreed with physical adsorption mechanism. The adsorption data fitted well to Freundlich, Langmuir and Frumkin adsorption isotherms

Prophylactic use of carvedilol to prevent ventricular dysfunction in patients with cancer treated with doxorubicin

Objective: Deterioration in ventricular function is often observed in patients treated with anthracyclines for cancer. There is a paucity of evidence on interventions that might provide cardio-protection. We investigated whether prophylactic use of carvedilol can prevent doxorubicin-induced cardiotoxicity and whether any observed effect is dose related. Methods: A prospective, randomized, double-blind study in patients treated with doxorubicin, comparing placebo (n = 38) with different doses of carvedilol [6.25 mg/day (n = 41), 12.5 mg/day (n = 38) or 25 mg/day (n = 37)]. The primary endpoint was the measured change in left ventricular ejection fraction (LVEF) from baseline to 6 months. Results: LVEF decreased from 62 ± 5% at baseline to 58 ± 7% at 6-months (p = 0.002) in patients assigned to placebo but no statistically significant changes were observed in any of the 3 carvedilol groups. At 6 months, only one of 116 patients (1%) assigned to carvedilol had an LVEF &#60; 50% compared to four of the 38 assigned to placebo (11%), (p = 0.013). No significant differences were noted between carvedilol and placebo in terms of the development of diastolic dysfunction, clinically overt heart failure or death. Conclusions: Carvedilol might prevent deterioration in LVEF in cancer patients treated with doxorubicin. This effect may not be dose related within the studied range