Multi-dimensional Resistivity Models of the Shallow Coal Seams at the Opencast Mine 'Garzweiler I' (Northwest of Cologne) inferred from Radiomagnetotelluric, Transient Electromagnetic and Laboratory Data

The entire Cenozoic unconsolidated fill of the Lower Rhine Embayment in Germany hosts the largest single lignite, or brown coal, deposit in Europe which covers an area of some 2,500 km2 to the northwest of Cologne. Rhineland brown coal is mined in large-scale opencast mining and accounts for around one-quarter of the public electricity supply in Germany. The present study was devoted to carrying out radiomagnetotelluric (RMT) and transient electromagnetic (TEM) investigations over the shallow coal seams at the opencast mine 'Garzweiler I.' The main objectives of the survey were to highlight the applicability and efficiency of RMT and TEM methods in an area like brown coal exploration, and to image the vertical electrical resistivity structure of these coal seams. Therefore, the vertical and lateral resolution capabilities of such methods were as necessary as the ability to cover large areas. Consequently, a total of 86 azimuthal RMT and 33 in-loop TEM soundings were carried out along six separate profiles over two opencast benches at the 'Garzweiler I' mine. The local stratigraphy at the survey areas comprises a layer-cake sequence, from top to bottom, of Garzweiler, Frimmersdorf and Morken coal seams embedded in a sand background, consisting of Surface, Neurath, Frimmersdorf and Morken Sands. A considerable amount of clay and silt intervenes the whole succession. The data were interpreted extensively and consistently in terms of one-dimensional (1D) RMT and TEM resistivity models, without using any complex multi-dimensional interpretation. However, the presence of thin, surficial clay masses (or lenses) broke down such interpretation scheme. In this case, to greatly improve the resistivity resolution for these surficial masses and the underlying coal seams, two-dimensional (2D) RMT and three-dimensional (3D) TEM interpretations have been carried out. They could be used effectively to study the local EM distortion on the measured data, where these surficial masses were found, as well as to cross-check the nearby-topography effect. Because the RMT data are usually skin-depth limited, they only provided a resolution depth between 25 and 30 m for the shallow resistivity structures. Whereas, the TEM data still have sufficiently early- to late-time information, and therefore resulted in a better resolution depth of about 100 m for the shallow to sufficiently-deep resistivity structures. The final 1D/2D RMT and 1D/3D TEM resistivity models displayed a satisfied correlation with both thicknesses derived from the stratigraphic-control boreholes and resistivities measured from direct-current (DC) and spectral induced polarization (SIP) laboratory techniques on 16 rock samples. As demonstrated, the integrated use of azimuthal RMT and in-loop TEM soundings was highly successful and effective at mapping the major stratigraphic units at the survey areas, i.e. the shallowest conductive Garzweiler and Frimmersdorf Coals within their fairly resistive sand background. They could not distinguish between Neurath Sand and the underlying sand/silt or between Frimmersdorf Coal and the underlying organic clay. The deepest Morken Coal was beyond the depth-of-investigation of the present measurements. Finally, the resistivity models revealed that both coal seams gently dip in the southwesterly direction. This should be in fairly good agreement with the regional structural makeup of the Rhineland brown coal. However, they showed that Garzweiler Coal is gradually thinned northeastwards, while Frimmersdorf Coal still has almost a regular thickness

Carbon diffusion in 304I austenitic stainless steel at 650 steel at 650 -750°c in carburizing environment

A 304L austenitic stainless steel is widely used in the petrochemical industry. As it is exposed to carburizing environment, carbon diffuses into metal and form carbides. Effect of the environment on the carbon diffusion is interesting to be known. This study will evaluate the effect of CH4 /H2 gas concentration and carburizing temperature on carbon diffusion in 304L austenitic stainless steel. Horizontal furnace equipped with a quartz tube and vacuum pump was used to expose the samples to carburizing environment at 650°C - 750°C and 20% - 40% CH4 /H2 gas composition for 100 hours. Optical microscopy examination of cross-sectioned specimens of 304L stainless steel showed that no carburizing zone formed after the samples subjected to 20% CH4 /H2 gas composition at 650˚C. It is observed that low carbon deposited on substrates with an average 0.0011g and carbon activity, ac , equal to 0.31. In comparison, with 40% CH4 /H2 gas composition at 650˚C, the average carbon deposited on the surface was two times more and carbon activity increased more than one, known as carburizing zone. Carbon diffusion at 750°C was deeper than at 650°C for both CH4 /H2 gas concentrations 20% - 40%. In conclusion the depth of the carburization zone increases with increasing the temperature from 650˚C to 750˚C and increases with increasing percentage of CH4 /H2 gas composition

Educational Debate in Egypt

The discourse on education in Egypt uses key terms such as reform and crisis. It is rare to find a society that is satisfied with its educational system. What seems important here is to analyse that which is considered as related to education. In other words, to what extent education is considered among the major causes of societal problems or, as the magic solution to these problems

Kristalna struktura i optička svojstva sustava Bi-Sb-Te-Se

The quaternary systems of Bi-Sb-Te-Se were synthesized by direct fusion technique. Thin films of these compounds were prepared by thermal evaporation under vacuum of 10−4 Pa. The structural properties of these compounds in powder and thin film forms were investigated by X-ray diffraction. The optical constants (absorption coefficient and band gap) of the thin films were determined by measurements of IR absorbance in the region 2.5 – 10 µm. Analysis of the optical absorption spectra revealed the existence of two direct energy gaps.Sintetizirali smo sustave Bi-Sb-Te-Se sa četiri sastavnice izravnom metodom staljivanja. Tanke slojeve tih spojeva pripremali smo isparavanjem u vakuumu (na 10−4 Pa). Primjenom rendgenske difrakcije odredili smo strukturna svojstva praha i tankih slojeva tih spojeva. Optičke konstante tankih slojeva (koeficijent apsorpcije i procijep med–u vrpcama) odredili smo mjerenjem apsorpcije u području 2.5 – 10 µm. Analiza optičkih apsorpcijskih spektara pokazuje dva izravna procijepa

A comparison between destructive and non- destructive techniques in determining coating thickness

Measuring coating thickness is an important part in research works related to coating applications. In general, techniques for measuring coating thickness may be divided into destructive and non-destructive methods which are commonly used depending on the applications. The objective of this study is to compare two methods measuring the coating thickness of electroplating copper coating on the austenitic stainless-steel substrate. The electroplating was carried out in a solution containing 200 g/L CuSO4, 100 g/L H2SO4 at room temperature and current of 40mA/cm2 during 20,40,60,80 and 100 mins as coating periods. And the coating thickness was measured by two methods, cross sectional analysis as a destructive technique and weight gain as a non-destructive technique. The results show that at 20 mins coating time interval, the thickness measured by cross sectional method was 16.67 µm and by weight gain method was 17.37 µm, with difference of 0.7 µm and percentage error of 4.11%. This error increased to 5.27% at 100mins time interval, where the values of the thickness measured by cross sectional and weight gain were 86.33 µm and 81.9 µm respectively, and the difference was 4.43 µm. Moreover, though the weight gain method is fast and gives the indication for the termination of a coating process, information regarding the uniformity, porosity and the presence of cracks cannot be obtained. On the other hand, determining the coating thickness using destructive method will damage the sampl

Comparative studies on the efficacy of lincomycin and bacitracin for the control of necrotic enteritis in broiler chickens

Background: The present study was conducted to evaluate the efficacy of lincomycin and/or bacitracin for control of experimentally-induced Clostridium perfringens (CP) infection in broiler chickens.Methods: A total of 100 one-day-old Cobb-mixed chicks were divided into five groups (A, B, C, D and E, each of 20 bird). At the 15th day of age, all birds (except group A) were inoculated orally with CP broth culture (109 CFU/mL). Two days later, drugs were orally administered once daily for five consecutive days as follow; Group A and B were left untreated. Group C, D, and E were treated with lincomycin (0.5 g/l), bacitracin (100 mg/l), lincomycin and bacitracin, respectively. The efficacy of used drugs was estimated based on clinical symptoms, body weight, weight gain, feed conversion rate. Hematobiochemical changes were also determined.Results: Necrotic enteritis in broiler chickens induced a significant decrease in body weight, weight gain, erythrocytic count, hemoglobin content, PCV %, serum proteins, catalase, and superoxide dismutase. Additionally, a marked decrease in serum lipids was obtained. Furthermore, a significant increase in feed conversion rate, leukocytic count, phagocytic activity, phagocytic index, serum total globulin, γ globulin and malondialdehyde coupled with a marked increase in β and α globulins were determined. Medication of infected broilers with lincomycin and/or bacitracin improved clinical signs and reduced mortality rate to 8, 6 and 2%, respectively, as well as restored the performance and hematobiochemical alterations.Conclusions: a combination of lincomycin and bacitracin was of considerable value for the control of necrotic enteritis in broiler chickens