An experimental study is performed to investigate the enhancement of convective condensation heat transfer coefficient of steam at low pressure ina horizontal tube with helical twisted tape inserts. ...The results indicate substantialenhancement in the condensation heat transfer coefficient or the tape inserts with in therange 2.5 < H/D < 10. Dimensionless correlationfor design purposes are provided to predict the condensation heat transfer coefficientin terms of Nu, Nusselt number as a function of pi-groups Re(L), superficial liquid Reynolds, phi(L) the friction multiplier of Lockhartand Martinelli, Pr Prandtl number of the condensate and, H/D pitch to diameter ratio of the tape. The correlations could satisfy thedata with an accuracy of plus/minus 4% validating the correctness of the criteria employed inthe regression analysis.
The investigation of the microstructural development during solidification as well as wear performance of Nb and Mo added hypereutectic WCI hardface deposits with W and V as minor additives was aimed ...during the study. This would enable the development of the hardface deposits with superior abrasive performance for severe wear applications. The hardfacing alloys were deposited on carbon steel using self-shielded flux cored arc welding (FCAW) technique. Phase formation, microstructural and mechanical properties of hardface deposits were investigated in the as-deposited condition. The microstructural examination showed that the addition of alloying elements to the high-Cr WCI resulted in grain refinement of the primary proeutectic M7C3 (M = Cr and Fe) carbide phase. EDX analysis revealed that the addition of Nb and Mo resulted in the formation of MC (M = Mo and Nb) carbides which resulted in grain refinement and higher wear resistance. Phase investigation of the deposits using XRD analysis shows the existence of M7C3 for all alloys and MC carbides for alloy B, C and D along with the ferrite phase. The main wear mechanism observed for the base high-Cr WCI is abrasive wear, while hardface alloys with alloying addition showed surface delamination which was attributed to the presence of soft phase adjacent to the M7C3 carbides in the microstructure. Among all the alloys, hardface deposits prepared using a filler with 5.5 -Mo, 6 - Nb, 2 - W and 1 - V (wt%) addition showed highest wear resistance due to grain refinement, MC carbide formation and solid solution strengthening by W and V.
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•Nb and Mo addition to high Cr- white cast iron hardface deposits refined proeutectic M7C3 phase by forming MC phase.•Proeutectic M7C3 refinement, MC dispersion and strengthening by W and V additives contributed to the high wear performance.•The higher amount of Nb and Mo addition as well as W and V additives increased the wear resistance.
Fluorescent labeling of endogenous proteins for live-cell imaging without exogenous expression of tagged proteins or genetic manipulations has not been routinely possible. We describe a simple ...versatile antibody-based imaging approach (VANIMA) for the precise localization and tracking of endogenous nuclear factors. Our protocol can be implemented in every laboratory allowing the efficient and nonharmful delivery of organic dye-conjugated antibodies, or antibody fragments, into different metazoan cell types. Live-cell imaging permits following the labeled probes bound to their endogenous targets. By using conventional and super-resolution imaging we show dynamic changes in the distribution of several nuclear transcription factors (i.e., RNA polymerase II or TAF10), and specific phosphorylated histones (γH2AX), upon distinct biological stimuli at the nanometer scale. Hence, considering the large panel of available antibodies and the simplicity of their implementation, VANIMA can be used to uncover novel biological information based on the dynamic behavior of transcription factors or posttranslational modifications in the nucleus of single live cells.
Ceramic coatings were produced on AA7075 by plasma electrolytic oxidation (PEO) technique using a pulsed DC power source with different combinations of duty cycle (20% and 80%) and pulse frequency ...(50Hz and 1000Hz). The morphology and phase composition of these coatings were analyzed by a scanning electron microscope (SEM), optical profilometer and X-ray diffraction (XRD) technique. The corrosion behavior of the PEO coatings was evaluated using open circuit potential measurements, potentiodynamic polarization in 3.5% NaCl solution and salt spray test as per the ASTM B117 standard. The adhesion strength between the coatings and substrate was assessed through scratch testing. X-ray diffraction patterns show that the PEO coatings formed on AA7075 substrate are mainly composed of γ-Al2O3. The SEM analysis reveals more pores over the surface of the samples treated at 50Hz frequency and micro-cracks at 80% duty cycle. The 3D-images and depth profiles as obtained through optical profilometer confirmed that the 1000Hz frequency and 20% duty cycle produced a smoother coating with fine and shallow pore morphology. Further, the coating thickness as measured by eddy current thickness gauge and SEM coating cross section confirmed that the 1000Hz frequency and 20% duty cycle produced a thicker coating. Among all the PEO treated samples, because of the thicker coating and fine pore morphology, the sample treated at 1000Hz frequency and 20% duty cycle demonstrated the highest pitting potential of 440mV, highest polarization resistance (Rp) of 31kΩ·cm2 and the highest scratch resistance of 28.1N.
•Frequency, duty cycle, surface morphology and corrosion resistance were correlated.•Higher frequency produced a thicker coating with fine and shallow pore morphology.•Higher frequency and higher duty cycle produced micro-cracks on the coating surface.•Higher frequency and lower duty cycle improved corrosion and scratch resistance.
In this work cobalt substituted magnesium spinel ferrite having general formula Mg1-xCoxFe2O4 (where x = 0.0, 0.1, 0.15,0.2,0.25 and 0.3) was synthesized by solid state reaction method. All the ...sample are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometer (VSM) and dc resistivity measurements. XRD analysis confirms the formation of single phase spinel and the calculated lattice constant ‘aexp’ from XRD decreases as substitution of Co (x) is increased. The FTIR spectra reveled two prominent frequency bands in the wave number range 400–600 cm−1, which confirm the cubic spinel structure. Magnetic studies revealed that the saturation magnetization attains a maximum value when x = 0.2, and then decreases for higher concentration of (x). This non-linear trend in magnetization has been explained on the basis of redistribution of magnetic and non-magnetic cations among A and B sites of the spinel lattice. A significant influence of cation distribution observed on DC electrical resistivity and activation energy.
The present study investigates the effect of the TiO2 nanofluid on the formation of hydrocarbon, carbon-monoxide, nitrogen oxide and smoke emission from a neat mustard oil methyl ester fueled diesel ...engine. TiO2 nano particle with an average size of 50 nm was synthesized by sol-gel route. The synthesized particles are dispersed with mustard oil methyl ester at various concentrations (100 and 200 ppm) by the means of a mechanical homogenizer and an ultrasonicator. Experiments were conducted in a four-stroke, single-cylinder, diesel-engine, fuelled with diesel, neat mustard oil methyl ester and nanofluid incorporated methyl ester. From the obtained results, it can be recognized that methyl ester from mustard oil is potential candidate as an alternative fuel in existing diesel engine. Further, it is also observed that TiO2 nanofluid associated to mustard oil methyl ester reduced various emissions over neat mustard oil methyl ester.
•Feasibility of using mustard oil methyl ester as a neat fuel is investigated.•Effect of TiO2 nanofluid with mustard oil methyl ester is examined.•Addition of TiO2 nanofluid reduces HC, CO, NOx and smoke emissions of methyl ester.•Catalytic TiO2 enhances the thermal conductivity and improves the combustion rate.
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