2,738 research outputs found

    Silicon Nanowire Immunosensor for Detection of 8-Hydroxy-2^|^apos;-Deoxyguanosine Oxidative Stress Cancer Biomarker

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    A silicon nanowire-based immunosensor has been developed to determine the presence of 8-hydroxy-2'-deoxyguanosine (8-OHdG). This research demonstrates a process for the detection of 8-OHdG, which is an oxidative stress biomarker, in which elevated concentrations in urine and saliva can act as an indicator of the presence of acute leukaemia, colorectal, breast, lung and prostate cancers. The detection of elevated levels of this biomarker is critical in determining the presence of various mutagenesis and can be used to diagnose early stage cancer before initial symptoms appear. The surface functionalization process has involved the attachment of diazonium salt to the silicon nanowire surface with further stage which involves the reduction of PhNO2 to PhNH2. The antibody targeted against 8-OHdG was subsequently bound to the amine NH2 modified grafted layer of a 370 nm width nanowire. The immunosensor was evaluated through the use of current/voltage electrical probe monitoring in which a 2 ÎŒg/ml concentration of 8-OHdG was detected. A further comparison with phosphate buffered saline solution added to the sensor was observed to be negligible. The antibody-functionalised SiNW sensor has been used to detect binding of the 8-OHdG biomarker to the SiNW surface within sixty-seconds of exposure, making this a rapid cancer biomarker test

    Transformer Fault Early Warning System Model Using GSM Network

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    This paper presents the design and implementation of amobile embedded system using an Arduino microprocessor to monitorand record key operational indicators of a distribution transformer,such as transformer oil level, temperature and vibration of adistribution transformer in a substation. If there is any abnormalityor an emergency situation, the system sends SMS (Short MessageService) messages to designated mobile telephones containinginformation about the abnormality of the mentioned parameters.Providing early warning of the abnormality of the distributiontransformer can be accomplished by shutting down the entire unitwith the aid on-line monitoring system integrates with Global ServiceMobile (GSM) Modem. Furthermore, the design generally consiststand-alone single chip microcontroller, modem and sensor packageslocated on distribution transformer site. In general, the design isdeveloped for the user to easily recognize the distribution transformerthat is suffered by any high vibration and rise in temperatures andlocated in remote or suburban area which is rarely and hard to reachfor manual monitoring. The ultimate objective is to monitor thetransformer oil level and temperature of 24 hours, 7 days a weekcontinuously besides the current and voltage parameter whichincluded in basis monitoring syste

    Flow Characterization of Vapor Phase of Geothermal Fluid in Pipe Using Isotope 85Kr and Residence TIME Distribution Modeling

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    Measurement of vapor flow in geothermal pipe faces great challenges due to fast fluids flow in high-temperature and high-pressure environment. In present study the flow rate measurement has been performed to characterization the geothermal vapor flow in a pipe. The experiment was carried out in a pipe which is connected to a geothermal production well, KMJ-14. The pipe has a 10” outside diameter and contains dry vapor at a pressure of 8 kg/cm2 and a temperature of 170 oC. Krypton-85 gas isotope (85Kr) has been injected into the pipe. Three collimated radiation detectors positioned respectively at 127, 177 and 227m from injection point were used to obtain experimental data which represent radiotracer residence time distribution (RTD) in the pipe. The last detector at the position of 227 m did not respond, which might be due to problems in cable connections. Flow properties calculated using mean residence time (MRT) shows that the flow rate of the vapor in pipe is 10.98 m/s, much faster than fluid flow commonly found in various industrial process plants. Best fitting evaluated using dedicated software developed by IAEA expert obtained the PĂ©clet number Pe as 223. This means that the flow of vapor of geothermal fluids in pipe is plug flow in character. The molecular diffusion coefficient is 0.45 m2/s, calculated from the axial dispersion model. Received: 21 November 2013; Revised: 16 May 2014; Accepted: 23 May 201

    Flow Characterization of Vapor Phase of Geothermal Fluid in Pipe Using Isotope 85Kr and Residence Time Distribution Modeling

    Get PDF
    Measurement of vapor flow in geothermal pipe faces great challenges due to fast fluids flow in high-temperature and high-pressure environment. In present study the flow rate measurement has been performed to characterization the geothermal vapor flow in a pipe. The experiment was carried out in a pipe which is connected to a geothermal production well, KMJ-14. The pipe has a 10” outside diameter and contains dry vapor at a pressure of 8 kg/cm2 and a temperature of 170 oC. Krypton-85 gas isotope (85Kr) has been injected into the pipe. Three collimated radiation detectors positioned respectively at 127, 177 and 227m from injection point were used to obtain experimental data which represent radiotracer residence time distribution (RTD) in the pipe. The last detector at the position of 227 m did not respond, which might be due to problems in cable connections. Flow properties calculated using mean residence time (MRT) shows that the flow rate of the vapor in pipe is 10.98 m/s, much faster than fluid flow commonly found in various industrial process plants. Best fitting evaluated using dedicated software developed by IAEA expert obtained the PĂ©clet number Pe as 223. This means that the flow of vapor of geothermal fluids in pipe is plug flow in character. The molecular diffusion coefficient is 0.45 m2/s, calculated from the axial dispersion model. Received: 21 November 2013; Revised: 16 May 2014; Accepted: 23 May 201

    Preparation of silver nanoparticles in virgin coconut oil using laser ablation

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    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10−8, 1.6 × 10−8, 2.4 × 10−8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method

    Tunable Raman fiber laser induced by Rayleigh backscattering in an ultra-long cavity

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    We report an ultra-long Raman laser with a 46 km fiber length that behaved as a Rayleigh back-scattering–based optical feedback. The laser was tunable from 1550 nm to 1571 nm (3 dB bandwidth) with the insertion of an optical grating filter. Evaluations on the spectral evolution and power development were also performed from the results obtained. In fact, it was discovered that the spectral broadening effect between the modeless spectra resembled the same process that happens in a typical fiber cavity that has high reflectors at each cavity end. In addition, the output power showed a square-root development with respect to the input power

    The crystal growth and properties of novel magnetic double molybdate RbFe5_{5}(MoO4_{4})7_{7} with mixed Fe3+^{3+}/Fe2+^{2+}states and 1D negative thermal expansion

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    Single crystals of new compound RbFe5_5(MoO4_4)7_7 were successfully grown by the flux method, and their crystal structure was determined using the X-ray single-crystal diffraction technique. The XRD analysis showed that the compound crystallizes in the monoclinic space group P21/m, with unit cell parameters a = 6.8987(4), b = 21.2912(12) and c = 8.6833(5) Å, ÎČ = 102.1896(18)°, V = 1246.66(12) Å3^3, Z (molecule number in the unit cell) = 2, R-factor (reliability factor) = 0.0166, and T = 293(2) K. Raman spectra were collected on the single crystal to show the local symmetry of MoO4_4 tetrahedra, after the confirmation of crystal composition using energy dispersive X-ray spectroscopy (EDS). The polycrystalline samples were synthesized by a solid-state reaction in the Ar atmosphere; the particle size and thermal stability were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses. The compound decomposes above 1073 K in an Ar atmosphere with the formation of Fe(III) molybdate. The thermal expansion coefficient along the c direction has the value α = −1.3 ppm K−1^{−1} over the temperature range of 298–473 K. Magnetic measurements revealed two maxima in the magnetization below 20 K, and paramagnetic behavior above 50 K with the calculated paramagnetic moment of 12.7 ÎŒB per formula unit is in good agreement with the presence of 3_3Fe3+^{3+} and 2_2Fe3+^{3+} in the high-spin (HS) state. The electronic structure of RbFe5(MoO4)7 is comparatively evaluated using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations
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