23 research outputs found

    Preparation and spectroscopic studies of Hydroxyapatite embedded in Poly(N-Vinylpyrrolidone) matrix

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    Pure HAp powder was prepared by precipitation and HAp/PVP composites were prepared by casting technique. X-ray diffraction was performed to examine the crystallinity and the complexation between HAp and PVP when the amount of HAp increased. XRD and EDX analysis showed that the concentration 15 wt% is the most confirmation for the formation of HAp. SEM shows more than one form of HAp such as plates, needles and bundles in the morphological structure of pure HAp and 15 wt% of HAp. Two main weight loss regions and two peaks were observed in TGA and DSC thermograms that reveal reduction in the thermal stability of the prepared samples as HAp content increases. The activation energy of the films was decreased with increasing the concentration of HAp. DSC thermographs of the samples show that the values of the glass transition temperatures are decreased with increasing the content of HAp filler which suggest that HAp filler act as plasticizer. The conductivity–temperature plots show linear variation, which suggests an Arrhenius behavior. The conductivity increases with adding HAp content for low concentrations while decreased for the critical concentration (15 wt %) which confirms the XRD results

    Early Outcomes of Coronary Artery Bypass Grafting in Patients with Low Ejection Fraction

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    Background: Patients with low ejection fraction (EF) are at a higher risk for postoperative complications and mortality. Our objective was to assess the effect of low EF (<40%) on early clinical outcomes after coronary artery bypass grafting (CABG) and to determine the predictors of mortality. Methods: From June 2017 to February 2019, 170 consecutive patients underwent CABG. There were 120 patients with low EF (<40%; 37.49 ± 2.89%); 94 were men (78.3%), and the mean age was 55.83 ± 8.04 years. Fifty patients had normal EF (> 40; 57.90 ± 2.27 %), 41 were men (82.0%), and the mean age was 54.30 ± 7.01 years and used as a control group. Results: Overall 30-day mortality was 10/120 patients (8.3%). Factors associated with higher mortality were females ( 70.0% vs. 17.3%, P<0.001); older age (61.40 ± 7.01 vs. 55.32 ± 7.97 years, P=0.025); diabetes mellitus (100% vs. 51.8%; P=0.003); longer cardiopulmonary bypass time (148.70 ± 40.12 vs. 108.49 ± 36.89 min; P=0.012); longer cross clamp time (88.19 ± 31.94 vs.64.77 ± 22.67 min; P=0.049), longer total operative time (6.82 ± 1.03 vs 5.38 ± 0.95 hours; P=0.001); intra-aortic balloon pump (IABP) insertion (90.0% vs. 10.9%; P<0.001); intra-operative complications (60% vs. 1.8%, P<0.001); ventricular tachycardia and ventricular fibrillation (30% and 50% vs. 4.5% and 5.5% respectively; P=0.002 for both); myocardial infarction (70% vs 11.8%, P<0.001), and lower postoperative ejection fraction (21.46 ± 1.93 vs 40.30 ± 8.19 %, P<0.001). In patients with low EF, postoperative NYHA and CCS angina class have improved compared to the preoperative levels (1.50 ± 0.61 vs. 3.31 ± 0.56; p< 0.001 and 1.38 ± 0.52 vs. 3.11 ± 0.55; p< 0.001 respectively) Conclusion: Patients with low EF have a higher risk of morbidity and mortality; however, the clinical and echocardiographic parameters improve over time. Therefore, CABG remains a viable option in selected patients with low EF. Factors affecting our 30-days mortality were related to the severity of the disease

    Physical properties of MnCl2 fillers incorporated into a PVDF/PVC blend and their complexes

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    Films of a PVDF/PVC blend filled with different concentrations of MnCl2 were prepared by using a casting technique. The prepared films were investigated by different methods. X-ray diffraction scans revealed the amorphous nature of the blend for low concentrations and a crystalline nature for higher ones. Results obtained by FTIR led to conclusions about the specific interactions in the polymer matrices and hence about the complexation. The morphological structure of the prepared samples was studied by SEM, which confirmed the results of XRD and DC electrical conductivity measurements. The ESR spectra of the samples exhibited resonance signals only after the introduction of Mn2þ ions into the blend. The DC conductivity was measured in the temperature range of 300–435 K in order to analyze the mechanism of the conduction. The conductivity–temperature plots were found to follow an Arrhenius relationship

    Risk analysis for preventive conservation of heritage collections in Mediterranean museums: case study of the museum of fine arts in Alexandria (Egypt)

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    Abstract The impacts of climate change on heritage collections in Mediterranean museums are serious and lead to accelerated material degradation, loss of value, increasing conservation costs and climatisation. Climate change scenarios and simulation models have been developed to predict the extreme and average future environmental conditions and to assess the future long-term risks caused by global warming for museum buildings and their collections in Mediterranean countries, with Egypt being particularly at risk. This paper presents the results of the risk analysis of the indoor and outdoor environments in Alexandria Museum of Fine Arts (AMFA) in Egypt to provide an overview of the current situation of conservation and museum management and to provide evidence-based data to support decision-making regarding preventive conservation given the museum's limited funding, capacity and resources. Unfortunately, the air quality in the museum cannot be considered satisfactory and specific measures need to be taken to improve the level of air quality and museum and building management. The results enabled an assessment of indoor air quality and provided information on potential risks to the museum building and collections, including variations in temperature (T) and relative humidity (RH), concentrations of NO2, SO2, O3, CO2, acetic and formic acid and lighting conditions, as well as the location and management of the museum. The results necessitate the development of a preventive conservation plan to address the challenges associated with high T/RH fluctuations and pollution pressure. This requires more regular use of the HVAC system within certain T/RH set points as well as minimising light exposure and the use of UV-filtering glazing. Care should be taken to ensure that housekeeping and emergency preparedness reduce the damping and salt florescence in the museum building. However, dealing with the impact of climate change on indoor and outdoor environments and museum collections in Mediterranean museums requires a holistic and adaptive approach that includes joint collaboration, research, training and strategic planning to ensure the long-term preservation of valuable cultural heritage collections in different climates with customised adaptations based on local environmental conditions, resources and needs. Resilience planning should be region-specific and take into account the potential impacts of extreme weather events, sea level rise and other climate-related challenges

    A new approach to evaluate the impact of thermophysical properties of nanofluids on heat transfer and pressure drop

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    In this paper, an experimental and numerical study was conducted to evaluate the impacts of momentum and thermal diffusivity comparing to the thermal conductivity of various types of nanofluids on turbulent forced convection heat transfer. 1%, 2%, and 3% volumetric concentrations of different nanofluids such as Al2O3-DW, SiO2-DW, and Cu-DW were considered in this study and their properties were evaluated numerically at the flow inlet temperature of 30 °C. The experimental works were conducted with distilled water as a working fluid to validate the 2-D numerical model. A two-dimensional domain was constructed using ANSYS-Fluent package, and the standard k–ε turbulence model was employed to solve the continuity, momentum, and energy equations. The flow was maintained in the Reynolds range between 6000 and 12,000, and the data obtained experimentally were validated by results from empirical correlations. The numerical solutions for the average Nusselt number and pressure drop presents a good agreement with the experimental results as the average error was less than 5% for both the cases of heat transfer and pressure loss data. The results showed that Al2O3-DW nanofluid has the best enhancement in convection heat transfer coefficient compared with the DW and other nanofluids of the same concentration while Cu-DW nanofluids shown the lowest enhancement though it shown the highest value of thermal conductivity. Also, the results showed that the product of kinematic and dynamic viscosities had the greatest effect on pressure drop in the fluid domain

    Copper Exposure Affects Anti-Predatory Behaviour and Acetylcholinesterase Levels in Culex pipiens (Diptera, Culicidae)

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    Copper is an essential metal that occurs chronically in the environment and affects the development and physiology of aquatic insects. In excess amounts, it can impair their nervous system and behaviour. We tested the anti-predatory behaviour of Cx. pipiens larvae after seven days exposure with several concentrations of copper up to 500 mg L−1. We measured responses to non- consumptive (predation cues) and consumptive predation (dragonfly larvae) across two generations. We also tested the accumulated effect of copper on AChE enzyme activity. We exposed half of treated and control larvae to predation cues (water with predator odour and crushed conspecifics) and the other half to water without predation cues. We evaluated total distance moved and velocity. Copper reduced the distance moved and velocity, with stronger effects in the second generation. Copper had no significant effect on larvae eaten by dragonflies. Copper inhibited the AChE enzyme across both generations at 500 µg L−1. Copper can affect the nervous system directly by inhibiting AChE activity, and possibly also by impairing the olfaction sensors of the larvae, resulting in larval inability to detect predation cues

    Prevalence of HBV and HCV infection among multi-transfused Egyptian thalassemic patients

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    BACKGROUND AND OBJECTIVES: Though regular blood transfusion improves the overall survival of patients with β-thalassemia, it carries a definite risk of infection with blood-borne viruses. The present study was carried out to estimate the real frequency of hepatitis B virus (HBV) and hepatitis C virus (HCV) among Egyptian b-thalassemic patients, and determine the infection-associated risk factors in these patients. DESIGN AND SETTING: A prospective study conducted in a university hospital from January 2009 to January 2010. PATIENTS AND METHODS: Two hundred patients with β-thalassemia major were enrolled in this study. Using enzyme-linked immunoabsorbent assay (ELISA), their sera were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis C core antigen (anti-HBc), and HCV antibody (HCV Ab). The positive HCV Ab results were confirmed by second generation recombinant immunoblot assay (RIBA). RESULTS: The study sample consisted of 111 males and 89 females, with a median age of 13 years. Eighty-one (40.5%) patients were HCV Ab positive by ELISA and 39 (19.5) were anti-HCV positive By RIBA; 58 (29.0%) were HBsAg positive and 13 (6.5%) were anti-HBc positive. Older age, an increased number of transfusion units, and HBsAg seropositivity were significantly associated with a higher prevalence of HCV and HBV. CONCLUSION: The prevalence of HCV and HBV infections are very high among Egyptian b-thalassemic patients, which calls for a critical look into the prevailing transfusion practices and adoption of stricter donor selection criteria to decrease the incidence rate of both HCV and HBV infections effectively. Furthermore, there is a compressing need for the use of more specific and sensitive methods for HCV testing in Mansoura University Hospitals
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