A Review on Developments in Electrolytes and their Feeding Methods for ECDM Process

Silicon - The need for electrochemical discharge machining (ECDM) has risen recently owning to the desire to produce micro-features in hard-to-machine materials. Electrolytes and their feeding...     

Development of supercritical water heat-transfer correlation for vertical bare tubes

This paper presents an analysis of heat-transfer to supercritical water in bare vertical tubes. A large set of experimental data, obtained in Russia, was analyzed and a new heat-transfer correlation for supercritical water was developed. This experimental dataset was obtained within conditions similar to those in supercritical water-cooled nuclear reactor (SCWR) concepts.The experimental dataset was obtained in supercritical water flowing upward in a 4-m long vertical bare tube with 10-mm ID. The data were collected at pressures of about 24 MPa, inlet temperatures from 320 to 350 °C, values of mass flux ranged from 200 to 1500 kg/m² s and heat fluxes up to 1250 kW/m² for several combinations of wall and bulk-fluid temperatures that were below, at, or above the pseudocritical temperature.A dimensional analysis was conducted using the Buckingham Π-theorem to derive the general form of an empirical supercritical water heat-transfer correlation for the Nusselt number, which was finalized based on the experimental data obtained at the normal and improved heat-transfer regimes. Also, experimental heat transfer coefficient (HTC) values at the normal and improved heat-transfer regimes were compared with those calculated according to several correlations from the open literature, with CFD code and with those of the proposed correlation.The comparison showed that the Dittus-Boelter correlation significantly overestimates experimental HTC values within the pseudocritical range. The Bishop et al. and Jackson correlations tended also to deviate substantially from the experimental data within the pseudocritical range. The Swenson et al. correlation provided a better fit for the experimental data than the previous three correlations at low mass flux (∼500 kg/m² s), but tends to overpredict the experimental data within the entrance region and does not follow up closely the experimental data at higher mass fluxes. Also, HTC and wall temperature values calculated with the FLUENT CFD code might deviate significantly from the experimental data, for example, the k-? model (wall function). However, the k-? model (low Reynolds numbers) shows better fit within some flow conditions.Nevertheless, the proposed correlation showed the best fit for the experimental data within a wide range of flow conditions. This correlation has an uncertainty of about ±25% for calculated HTC values and about ±15% for calculated wall temperature. A final verification of the proposed correlation was conducted through a comparison with other datasets. It was determined that the proposed correlation closely represents the experimental data and follows trends closely, even within the pseudocritical range. Finally, a recent study determined that in the supercritical region, the proposed correlation showed the best prediction of the data for all three sub-regions investigated.Therefore, the proposed correlation can be used for HTC calculations in SCW heat exchangers, for preliminary HTC calculations in SCWR fuel bundles as a conservative approach, for future comparison with other datasets and for the verification of computer codes and scaling parameters between water and modelling fluids.     

Bupropion and anticonvulsant drug interactions

The haemolytic uraemic syndrome, first described in 1955 by Gasser, is the number one cause of acute renal failure in infants. There are three types of the haemolytic uraemic syndrome: the seasonal epidemic form with prodromic diarrhoea and generally favourable outcome which usually occurs in infants, a less typical form without signs of digestive tract involvement and no seasonal prevalence which occurs more readily in older children and sometimes in families has a less favourable prognosis, and finally drug- or disease-related forms. Currently, overall mortality due to haemolytic uraemic syndrome has been reduced to about 4%, usually as a result of damage to the central nervous system. Several microorganism, including Shigella dysenteriae, Salmonella typhi, Campylobacter jejuni, Streptococcus pneumoniae, Rickittsiae and certain viruses (Coksackiae, Influenzae, Epstein-Barr) have been identified as causative agents. In 1983, digestive tract infection due to an Escherichia coli strain producing verotoxin was identified as capable of producing haemolytic uraemic syndrome and more rarely thrombopenic thrombotic purpura. The germ produces two exotoxins (whose effect is accentuated by the E. coli lipopolysaccharide endotoxin) which lead to the glomerular microangiopathy causing haemolytic uraemic syndrome. Diagnosis is based on identification (monoclonal antibodies, ELISA, PCR) of the verotoxins themselves or the two encoding genes in stool samples. Symptomatic treatment is essential but the effectiveness of antibiotics is still debated. Theoretically, antibiotics could worsen the syndrome by increasing endotoxin release from lysed bacteria, but inversely they could also prevent the syndrome if given early enough. Further research is required to acquire precise epidemiological data and identify animal reservoirs of verotoxin producing E. coli.     

Sunset yellow dyed triglycine sulfate single crystals: enhanced thermal,mechanical, optical and di-/piezo-/ferro-/pyro-electric properties

Single crystals of pure and sunset yellow (SSY) dye doped (0.05 mol%) triglycine sulphate (TGS) were grown by slow evaporation solution technique with the vision to improve the properties of pure TGS crystal. The external morphology of TGS crystal was deduced from its internal crystal structure by using two of the well established models, namely Bravais–Friedel–Donnay–Harker model (B–F–D–H) and Hartman–Perdok (H–P) periodic-bound chain (PBC) vectors model. The selective nature of sunset yellow dye to selectively stain the particular growth sectors of TGS crystal was studied. The structural analysis of both the crystals was carried out using powder XRD and FTIR studies. UV–Vis–NIR spectroscopy was carried out on both pure and SSY dyed TGS crystals to study their linear optical properties and various optical parameters namely optical band gap, refractive index, extinction coefficient and optical conductivity were determined. The thermal stability, melting point, ferro- to para-electric transition temperature, piezoelectric charge coefficient, ferroelectricity and mechanical hardness got enhanced as an effect of SSY dye doping in TGS matrix. The piezoelectric conversion efficiency (d₂₂) got enhanced from ~?56 pm/V for pure TGS single crystal to ~?85 pm/V for SSY doped TGS single crystal. The true-remanent polarization was determined for dyed TGS crystal using ‘Remanent Hysteresis Task’ which showed the presence of very small contributions of non-switchable components. ‘Time-Dependent Compensated (TDC)’ hysteresis task revealed the absence of resistive leakage in SSY-Doped TGS crystal. The pyroelectric coefficient got enhanced from ~?761 µCm^?2/°C for pure TGS single crystal to ~?850 µCm^?2/°C for SSY doped TGS single crystal. Comparative optical, mechanical, dielectric, piezoelectric, ferroelectric and pyroelectric studies provide useful scientific information of an important class of TGS crystals and suggest SSY-Doped TGS crystal as a better alternative than pure TGS crystal for various opto-electronics and ferroelectric devices applications.     

Nano-surface-finishing of permanent mold punch using magnetorheological fluid-based finishing processes

Various plastic products such as bottles’ plastic caps are manufactured through casting using permanent molds. To obtain the smooth surface on plastic caps during manufacturing, the required permanent mold die punch surface should be defect free and its roughness values in nanometer range. Two different magnetorheological (MR) fluid-based finishing processes are used for nano-surface-finishing of die punch. The MR ball end with solid rotating tool core is used to finish the flat surface, and a turning type MR finishing process is used for external circular surface of the present mold die punch. The material of the present permanent mold punch is P20 tool steel with hardness of 431 VHN. The final roughness values of flat and external circular surfaces of the present die punch are obtained as 30?nm and 80?nm from the initial values of 1080?nm and 630?nm in 120?min of finishing. The change in topography of the surface is observed using metallurgical microscope and mirror image test. The reduction in surface roughness at the nanolevel and microscopic improvement on the die punch surface have demonstrated the feasibility of present finishing processes to be useful in industries for manufacturing the smooth surface of bottles’ plastic caps.     

A lightweight IoT‐based security framework for inventory automation using wireless sensor network

Internet of things (IoT) has evolved as an innovation of next generation in this world of smart devices. IoT tends to provide services for data collection, data management, and data and device security required for application development. Things or devices in IoT communicate and compute to make our lives comfortable and safe. In inventory automation, real‐time check on items, their information management, and status management, monitoring can be carried out using IoT. The huge amount of data that flows among the devices in the network demands for a security framework that ensures authentication, authorization, integrity, and confidentiality of data. The existing security solutions like SIMON or SPECK offer lightweight security solutions but are vulnerable to differential attack because of their simplicity. Moreover, existing solutions do not offer inbuilt authentication. Therefore, this research work contributes a secure and lightweight IoT‐based framework using wireless sensor network (WSN) as a technology. The existing security solutions SPECK and SIMON are compared with the proposed security approach using COOJA simulator. The results show that proposed approach outstands others by 2% reduction in number of CPU cycles, 10% less execution time, 4% less memory requirements of security approach, and with minimum 10% more security impact.     

The blockchain conundrum: An in-depth examination of challenges,contributing technologies,and alternatives

The accelerated development of information and communication technologies has generated a demand for data storage that is effective, transparent, immutable, and secure. Distributed ledger technology and encryption techniques such as hashing and blockchain technology revolutionised the landscape by meeting these requirements. However, blockchain must overcome obstacles such as low latency, throughput, and scalability for its full potential. Investigating blockchain's structure, types, challenges, promises, and variants is necessary to understand blockchain and its capabilities comprehensively. This paper overviews various aspects, such as emergent blockchain protocols, models, concepts, and trends. We classify blockchain variants into five essential categories, DAG, TDAG, Sharding, Consensus, and Combining methods, based on the structure each follows, and conduct a comparative analysis. In addition, we explore current research tendencies. As technology progresses, it is essential to comprehend the fundamental requirements for blockchain development.     

CAD synthesis tools for floating-gate SoC FPAAs

Design Automation for Embedded Systems - We present a tool framework to compile and program mixed-signal circuits and systems on Floating-Gate (FG) based mixed-signal System-on-Chips (SoC)...