Experimental investigation of Al2O3/8YSZ and CeO2/8YSZ plasma sprayed thermal barrier coating on diesel engine

In this research work, aluminium oxide/yttria stabilized zirconia (20%Al₂O₃/80%8YSZ) and ceria/yttria stabilized zirconia (20%CeO₂/80%8YSZ) were coated through atmospheric plasma spray technique (APS) as thermal barrier coating (TBC) over CoNiCrAlY bond coat on aluminium alloy (Al-13%Si) substrate piston crown material and their thermal cycling behavior were studied experimentally. Thermal cycle test of both samples were conducted at 800?°C. Microstructural, phase and elemental analysis of the TBC coatings were experimentally investigated. The performance, combustion and emission characteristics of Al₂O₃/8YSZ, CeO₂/8YSZ TBC coated and uncoated standard diesel engine were experimentally investigated. The test results revealed that CeO₂/8YSZ based TBC has an excellent thermal cycling behavior in comparison to the Al₂O₃/8YSZ based TBC. The spallation of the Al₂O₃/8YSZ TBC occurred mainly due to the formation of thermally grown oxide (TGO), and growth of residual stresses at top coating and bond coating interface. The experimental results also revealed that the increase of brake thermal efficiency and reduction of specific fuel consumption for both TBC coated engine. Further reduction of HC, CO and smoke and increase of NOx emission were recorded for both TBC coated engine compared to the standard diesel engine.     

Effect of Load and Composition on Friction and Dry Sliding Wear Behavior of Tungsten Carbide Particle-Reinforced Iron Composites

Investigations on the dry sliding wear behavior of tungsten carbide (WC)-reinforced iron matrix composites were carried out at room temperature. Three sets of samples (unreinforced iron, 4 wt% micrometer-size (～5–15 μm) WC-reinforced iron and 4 wt% nanosize (～30 nm) WC-reinforced iron were prepared using a powder metallurgy route to assess their friction and wear behaviors under two different loads. The relative dry sliding wear performances of the micrometer-size and nanosize WC-reinforced composites were compared with unreinforced matrix. An increase in microhardness of the order of 2.5 times was observed in the case of 4 wt% nanosize WC-reinforced iron matrix compared to the unreinforced iron matrix. The wear rate was 1.35 to 1.45 times lower in the case of nanocomposites compared to the unreinforced iron matrix (under different experimental conditions). The values of the coefficient of friction (COF) of composites were found to decrease with increase in load. Nanocomposites showed lower COF, surface roughness, and fractal dimension (D) values than micrometer-size WC-reinforced composites and the unreinforced iron matrix.     

Preparation and characterization of mesostructured Zr-SBA-16: efficient Lewis acidic catalyst for Hantzsch reaction

Journal of Porous Materials - Mesostructured Zr-SBA-16 (3D cubic arrangement, Im3m space group) with different Si/Zr ratio was successfully synthesized by using Pluronic F127 triblock copolymer and...     

An Improved Direct Digital Synthesizer Using Hybrid Wave Pipelining and CORDIC algorithm for Software Defined Radio

The improved Direct Digital Synthesizer (DDS) using the Hybrid Wave Pipelining (HWP) technique and COordinate Rotation DIgital Computer (CORDIC) algorithm for Software Defined Radio (SDR) is presented in this paper. In order to achieve high throughput, the hybrid wave pipelining technique is adopted. The HWP can be used to speed up the circuits without insertion of storage elements. The CORDIC algorithm is used for phase-to-amplitude conversion and utilized for dynamic transformation rather than Read Only Memory (ROM) static addressing. The frequency resolution and phase resolution are achieved as 0.023 Hz and 0.088 degree, respectively, at the maximum operating frequency of 199.288 MHz for the proposed DDS architecture. The spectral purity of the proposed design has been improved to 114 dBc with a throughput of 94 %. This paper is focused on the design and implementation of DDS using hybrid wave pipelining with CORDIC approach to target on Xilinx Spartan 3 (XC3S400-5PQ208) Field Programmable Gate Array (FPGA) with a speed grade of ?5. The proposed DDS design reduces the gate count from 49.4 % to 18.2 % as compared to the conventional pipelined Read Only Memory Look Up Table (ROMLUT) DDS method. The throughput of the proposed method has been improved from 78 % to 94 % and 55 % of total power reduction as compared with conventional DDS. The performance of the improved DDS architecture is compared with several existing DDS architectures and it is found that the present design is outperforming and can be used for software defined radios.     

Minimization of Moisture Readsorption in Dried Coal Samples

Low-rank coals csonstitute a major energy source for the future as reserves of such high-moisture coals around the world are vast. Currently they are considered undesirable since high moisture content entails high transportation costs, potential safety hazards in transportation and storage, and the low thermal efficiency obtained in combustion of such coals. Furthermore, low-moisture-content coal is needed for the various coal pyrolysis, gasification developed. Hence, various upgrading processes have been developed to reduce the moisture content. Moisture readsorption and spontaneous combustion are important issues in coal upgrading processes. This article discusses results of laboratory experiments conducted to study the options for minimization of readsorption of moisture after drying of selected coal samples. Results suggest that there is little benefit in drying low-rank coal at high temperatures. It was found that the higher the amount of bitumen used for coating, the lower is the readsorption of moisture by dried coal. Also, mixing high-temperature-dried coal with wet coal in appropriate proportion can yield reduced moisture content as the sensible heat in the hot coal is utilized for evaporation.     

Electrochemical Deposition of 58SiO2‐33CaO‐9P2O5 Nanobioactive Glass Particles on Ti‐6Al‐4V Alloy for Biomedical Applications

The nanobioactive glass (58SiO₂‐33CaO‐9P₂O₅) powders were synthesized by simple sol–gel method. The prepared samples reveal amorphous nature, agglomerated spherical morphology with particle size of 100–150 nm. The specific surface area of nanobioactive glass (NBG) particle is 147 m²/g. The NBG samples were coated on titanium (Ti‐6Al‐4V) alloy through electrochemical deposition method. The particle size of the NBG‐coated surface was in the order of 200–300 nm, and it was confirmed by atomic force microscopy (AFM) analysis. In vitro and AFM studies reveal the existence of higher bioactivity and uniform coating of NBG on implants at 80 V for 1 h.     

Magnetic Tweezers‐Based 3D Microchannel Electroporation for High‐Throughput Gene Transfection in Living Cells

A novel high‐throughput magnetic tweezers‐based 3D microchannel electroporation system capable of transfecting 40 000 cells/cm² on a single chip for gene therapy, regenerative medicine, and intracellular detection of target mRNA for screening cellular heterogeneity is reported. A single cell or an ordered array of individual cells are remotely guided by programmable magnetic fields to poration sites with high (>90%) cell alignment efficiency to enable various transfection reagents to be delivered simultaneously into the cells. The present technique, in contrast to the conventional vacuum‐based approach, is significantly gentler on the cellular membrane yielding >90% cell viability and, moreover, allows transfected cells to be transported for further analysis. Illustrating the versatility of the system, the GATA2 molecular beacon is delivered into leukemia cells to detect the regulation level of the GATA2 gene that is associated with the initiation of leukemia. The uniform delivery and a sharp contrast of fluorescence intensity between GATA2 positive and negative cells demonstrate key aspects of the platform for gene transfer, screening and detection of targeted intracellular markers in living cells.     

Investigations on structural, optical and electrochemical properties of blue luminescence SnO2 nanoparticles

A simple solution approach has been developed to synthesis SnO₂ nanoparticles using polyethylene glycol as stabilizer. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), UV–Vis absorption spectroscopy, photoluminescence (PL) emission spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the nanoparticles. XRD, HR-TEM and AFM indicate that the SnO₂ nanoparticles correspond to tetragonal crystal structure with size ranges below Bohr’s exciton radius. UV–Vis absorption spectrum showed band gap exhibiting a 1.3 eV shift from that of bulk SnO₂ structures. The blue emission owing to transition of an electron from conduction band to deeply trapped hole in SnO₂ nanoparticles was analyzed using PL spectroscopy. The charge transfer capability had been investigated using CV and EIS in different electrolytes. A detailed exploration on confinement effect that occurred in SnO₂ nanoparticles, mechanism behind visible emission and electron transfer mechanism in different electrolyte was discussed.     

Fabrication,physiochemical and optoelectronic characterization of SiO2/CdS core–shell nanostructures

Silica/CdS core–shell nanostructures have been developed using a simple wet chemical route. This method utilizes silica spheres formation followed by successive ionic layer adsorption and reaction method assisted CdS shell layer formation. The morphological studies revealed the uniformity in size distribution with core size of 250 nm and shell thickness of 9 nm. The electron microscopic images also indicate the irregular morphology of CdS shell layer. The structural studies indicate the simple cubic system of CdS shell with no other trace for impurities in the crystal structure. This CdS layer exhibit the band gap energy of 2.66 eV, due to weak quantum confinement and numerous defects presence. The studies on room temperature photoluminescence measurement indicate the emission properties and the corresponding electronic energy levels of defect states. Further, the physiochemical understanding of core–shell formation mechanism clearly matches with the motive behind the defects present in the CdS shell layer.