Uji Prestasi Mesin Pendingin Kompresi Uap yang Menggunakan Refrigeran R22 dengan Metode Pengujian Aktual dan Simulasi

Sistem pengkondisian udara yang mengatur temperatur dan kelembaban udara dalam ruangan, dalam pengoperasiannya membutuhkan refrigeran yang mudah menyerap dan melepaskan kalor. Setiap refrigerant memiliki karakteristik yang berbeda-beda yang mempengaruhi efek refrigerasi dan koefesien prestasi yang dihasilkan. R 22 adalah salah satu refrigeran yang memiliki karakteristik yang baik pada mesin pendingin. Software Genetron properties adalah sebuah software simulasi yang dapat menghitung aliran fluida atau refrigerant pada mesin pendingin. Genetron properties melakukan simulasi termodinamika untuk siklus kompresi uap dan memberikan hasil dalam bentuk tabulasi dan pada diagram Mollier diagram (h-s diagram). Pengujian prestasi mesin pendingin yang menggunakan R-22 dilakukan secara aktual dan simulasi dengan menggunakan software genetron properties. Hasil pengujian dan perhitungan menunjukkan bahwa : Kerja kompresor, COP dan performance factor pada mesin pendingin kompresi uap ketika high speed adalah 0,528 kW, 8,42 dan 0,1187; saat low speed adalah 0,528 kW; 8,52 dan 0,117. COP dari hasil pengujian dengan software genetron properties ketika high speed 2,193 saat low speed 1,415 hal ini dikarenakan mesin pendingin kompresi uap dalam keadaan tidak optima

Study on Quality of Pair Distribution Function for Direct Space Approach of Structure Investigation

Study of the structure characteristics of solid materials is a key for development of technological applications. Potential of direct space approach for structure determination and refinement using powder X-ray diffraction data depend on the quality of pair distribution function (PDF) plot. So, the effect of data collection conditions and diffractogram characteristics on the quality of PDF plot has been investigated in detail. In addition, errors and possible tolerance have been estimated. Some parameters affect only either the X-ray diffractogram or PDF plots and others affect both. Considering the errors and tolerance, direct space approach can be confidently used for structure refinement, where the error did not exceed 10.0 % for inter-atomic radial distance longer than » 2.0 ? and 5.0 % for longer than » 4.0 ?, which is accepted for structure refinement. As tolerance is considered, every time the value of the lattice parameter is changed to smaller or larger than the correct value (+ 8.0 %), it comes back to the initial correct one. Although, advanced synchrotron radiation shows better data, conventional source can be used successfully for structure investigation applying direct space approach

Oxidative stress pattern in hepatitis C patients co-infected with schistosomiasis

This study was designed to investigate the role of hepatitis C virus (HCV)-induced oxidative stress in the pathogenesis of the disease with the measurement of tumor necrosis factor (TNF-∝) and super oxide dismutase (SOD). Eighty patients from Hepatology Unit, Faculty of Medicine, Ain Shams University, were investigated. Thirty patients with bilharzial HCV and 30 patients with non-bilharzial HCV as compared to 20 healthy controls of the same age and sex ratio were investigated. The concentrations of liver enzymes [glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP)], bilirubin (Bil), albumin (Alb) and total protein (TP) as well as TNF-α and Mn-SOD were determined. The mean level of the different liver function tests in the three groups in the study showed that the levels of GOT, GPT and ALP were significantly higher in the HCV groups as compared to the control group (p < 0.05). While serum bilirubin, albumin and total protein were non-significantly decreased in the HCV groups as compared to the control group (p > 0.05). Furthermore, the mean level of TNF-α was significantly higher in the HCV groups as compared to the control group (p < 0.001) and SOD was significantly decreased in the HCV groups as compared to the control group (p < 0.001). There is a cause-effect relationship between increased levels of TNF-α and decreased levels of SOD, relative to progression of chronic HCV, especially with bilharzias co-infection. Supporting the view that oxidative damage plays a role in chronic HCV infection, also TNF-α establishes a positive auto regulatory loop that can amplify the inflammatory response and lead to chronic inflammation. More evidence indicates that HCV block apoptosis and prolong survival of the host cell in order to gain time for replication and increase viral progeny production.Key words: Hepatitis C virus, tumor necrosis factor-alpha, superoxide dismutase, oxidative stress, schistosomiasis

Groundwater Quality Assessment Using Multi-Criteria GIS Modeling in Drylands: A Case Study at El-Farafra Oasis, Egyptian Western Desert

first_pagesettingsOrder Article Reprints Open AccessArticle Groundwater Quality Assessment Using Multi-Criteria GIS Modeling in Drylands: A Case Study at El-Farafra Oasis, Egyptian Western Desert by Hanaa A. Megahed 1,Hossam M. GabAllah 1,Rasha H. Ramadan 2ORCID,Mohamed A. E. AbdelRahman 2,*ORCID,Paola D’Antonio 3,*ORCID,Antonio Scopa 3ORCID andMahmoud H. Darwish 4ORCID 1 Division of Geological Applications and Mineral Resources, National Authority for Remote Sensing and Space Sciences (NARSS), Cairo 1564, Egypt 2 Division of Environmental Studies and Land Use, National Authority for Remote Sensing and Space Sciences (NARSS), Cairo 1564, Egypt 3 Scuola di Scienze Agrarie, Forestali, Alimentari ed Ambientali (SAFE), Università degli Studi della Basilicata, Viale dell’Ateneo Lucano, 10, 85100 Potenza, Italy 4 Geology Department, Faculty of Science, New Valley University, El Kharga 72511, Egypt * Authors to whom correspondence should be addressed. Water 2023, 15(7), 1376; https://doi.org/10.3390/w15071376 Received: 15 February 2023 / Revised: 26 March 2023 / Accepted: 27 March 2023 / Published: 3 April 2023 (This article belongs to the Special Issue Water Security, Water Economics and the Evolution of Water Consumption) Download Browse Figures Versions Notes Abstract The most critical issue that was the main research interest is its groundwater quality which is vital for public health concerns. Groundwater is a significant worldwide water supply for diverse communities, especially in dryland regions. Groundwater quality assessment in desert systems is largely hindered by the lack of hydrological data and the remote location of desert Oases. This study provides a preliminary understanding of the influences of climate, land usage, and population growth on the groundwater quality in El-Farafra Oasis in the Western Desert in Egypt from 2000 to now. Therefore, the study’s main objective was to determine the extent of change in temporal water quality and the factors causing it. The present study integrates chemical analyses and geospatial modeling better to assess groundwater quality in the study area. A chemical analysis of thirty-one groundwater samples from wells representing each study area was carried out during three time periods (2000, 2010, and 2022). Several chemical properties of groundwater samples gathered from wells in the research area were analyzed. Furthermore, the groundwater quality trend from 2000 to the present was identified using three approaches: Wilcox and Schoeller Diagram in Aq.QA software, interpolation in the ArcGIS software, and Ground Water Quality Index (GWQI). Moreover, the influence of changing land usage on groundwater quality was studied, and it was found that the increase in agriculture and urbanization areas is linked to groundwater quality degradation. The findings revealed that the barren area in 2000, 2010, and 2022 was 371.7, 362.0, and 343.2 km2, respectively, which indicates a substantial decrease of 6.2% within this research timeframe. In contrast, agriculture and human-made structures have expanded by 1.8%. Also, population growth has led to an increase in water consumption as the population has grown at a rate of 7.52% annually from 2000 to 2020. As the climatic condition increases from 2000 to 2022, these changes could extend to the water quality in shallow aquifers with increasing evaporation. Based on the water quality spatial model, it is found that, despite a declining tendency in the rate of precipitation and an expansion in agricultural areas and population growth, the water quality was still appropriate for human and farming consumption in large areas of the study area. The presented approach is applicable to the assessment of groundwater in desert regions in the Middle East area

Subclinical hypothyroidism among Egyptian children with systemic lupus erythematosus

Background: Thyroid autoimmune diseases have been associated with systemic lupus erythematosus (SLE). Both hypothyroidism and hyperthyroidism are seen, but hypothyroidism is the most common abnormality. Subclinical hypothyroidism (SCH) has been reported among adult lupus patients. SCH is not without risk as it might contribute to a proatherogenic state. Objectives: This study was aimed to assess the frequency of SCH in a group of Egyptian children with SLE and its effects on the serum lipids. Methods: Forty patients with pediatric SLE who regularly follow up at our center were enrolled in this study. They were subjected to routine laboratory investigations of SLE and measurement of serum lipids (serum triglycerides, cholesterol, LDL and HDL) as well as free thyroxine (T4), thyroid stimulating hormone (TSH) and anti-thyroperoxidase antibody (anti-TPO-ab) titre. SLE activity was assessed using the systemic lupus erythematosus disease activity index (SLEDAI). Results: Six patients (15%) were found to have SCH while the remaining 34 patients (85%) had normal thyroid function. Anti-TPO-abs were positive in 4 out of the 6 (66.6 %) SLE patients with SCH and in 20 out of the 34 (58.8%) SLE patients with normal thyroid function. In SLE patients with SCH, TSH correlated positively yet insignificantly with anti-TPO-ab titre and the duration of SLE (p = 0.17, p = 0.12, respectively). There were no statistically significant correlations between the serum lipids of SLE patients with SCH and their thyroid function or anti-TPO-ab titre. Conclusion: SCH is not uncommon among children with SLE. This SCH does not seem to affect serum lipids. However, further longitudinal studies on wider scales are needed to assess the long term effects of SCH in those patients.Keywords: SLE, anti-thyroperoxidase antibodies, subclinical hypothyroidismEgypt J Pediatr Allergy Immunol 2011;9(2):87-9

In-situ Magnesium Diboride Superconducting Thin Films grown by Pulsed Laser Deposition

Superconducting thin films of MgB2 were deposited by Pulsed Laser Deposition on magnesium oxide and sapphire substrates. Samples grown at 450C in an argon buffer pressure of about 10-2 mbar by using a magnesium enriched target resulted to be superconducting with a transition temperature of about 25 K. Film deposited from a MgB2 sintered pellet target in ultra high vacuum conditions showed poor metallic or weak semiconducting behavior and they became superconducting only after an ex-situ annealing in Mg vapor atmosphere. Up to now, no difference in the superconducting properties of the films obtained by these two procedures has been evidenced.Comment: 10 pages, 4 figure