Effect of plasma electrolytic oxidation coating on the stress corrosion cracking behaviour of wrought AZ61 magnesium alloy

An attempt was made to understand the effect of silicate based plasma electrolytic oxidation (PEO) coating on the stress corrosion cracking (SCC) behaviour of an AZ61 wrought magnesium alloy. The SCC behaviour of untreated and PEO coated specimens was assessed using slow strain rate tensile tests at two different nominal strain rates, viz. 1 × 10⁻⁶ s⁻¹ and 1 × 10⁻⁷ s⁻¹, in ASTM D1384 test solution at ambient conditions. The PEO coating was found to improve the general corrosion resistance to a significant extent; however, the improvement in the resistance to stress corrosion cracking was only marginal.     

The effect of blanching on the quality of dehydrated broccoli florets

Different blanching treatments were applied to broccoli florets prior to dehydration in order to improve product quality. The pretreatments used were a conventional blanching in water at 99ǃ °C, and a stepwise blanching (a blanching at low temperature followed by a short blanching at high temperature after a holding time) using different temperatures for the first step (50, 55, 60, 65 and 70 °C). Five rehydration temperatures were used (25, 40, 55, 65 and 80 °C). Rehydration rate (D_eff and W_e), chlorophyll content and texture of the rehydrated product were evaluated. Rehydration was modelled according to Fick's diffusion equation. A good agreement between the model and the experimental data was obtained when D_eff and W_e values were identified for each temperature (average explained variance 96.9%). Samples stepwise blanched at 60 °C showed, on the average, the lowest W_e values. Stepwise blanching at 60-65 °C and rehydration at 25-55 °C were the combinations that gave the firmest product. Stepwise blanching at 50 °C together with the conventional blanching (99ǃ °C) and rehydration between 25 and 65 °C were the combinations that allowed preservation of the highest chlorophyll content. From these results, it seems difficult to obtain firm samples with a high chlorophyll content without additives.     

Heavy metal accumulation in vegetables irrigated with water from different sources

The present study was carried out to assess levels of different heavy metals like iron, manganese, copper and zinc, in vegetables irrigated with water from different sources. The results indicated a substantial build-up of heavy metals in vegetables irrigated with wastewater. The range of various metals in wastewater-irrigated plants was 116–378, 12–69, 5.2–16.8 and 22–46 mg/kg for iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn), respectively. The highest mean levels of Fe and Mn were detected in mint and spinach, whereas the levels of Cu and Zn were highest in carrot. The present study highlights that both adults and children consuming vegetables grown in wastewater-irrigated soils ingest significant amount of these metals. However, the values of these metals were below the recommended maximum tolerable levels proposed by the [Joint FAO/WHO Expert Committee on Food Additives (1999). Summary and conclusions. In 53rd Meeting, Rome, June 1–10, 1999]. However, the regular monitoring of levels of these metals from effluents and sewage, in vegetables and in other food materials is essential to prevent excessive build-up of these metals in the food chain.     

Direct ink writing of bismuth molybdate microwave dielectric ceramics

Additive manufacturing via direct ink writing and microwave dielectric characterisation of commercially produced low sintering temperature bismuth molybdenum oxide ceramics, have been both performed for the first time, following a powder-to-product holistic approach. We demonstrated that direct ink writing is an excellent candidate for producing dielectric substrates to be used for wireless telecommunication applications operating at microwave (MW) frequencies, with great repeatability and properties comparable to ceramics fabricated via conventional processing routes. The optimum density (relative density of ρ_r ≈ 93%) of the 3D printed test samples was obtained by sintering at 660 °C for 2 h, resulting in a relative permittivity ε_r = 35.7, dielectric loss tanδ = 0.0004 and microwave quality factor Q × f = 14,928 GHz. Sintering at higher temperatures promoted a porosity increase due to mismatching grain growth mechanisms and phase decomposition, that collectively hindered the test samples’ microwave dielectric performance in terms of achievable relative permittivity (ε_r) and dielectric loss (tanδ).     

Heat and mass transfer for Soret and Dufour's consequences on unsteady MHD free convection flow over a porous media with heat absorption

The significance of this article lies in explaining the influence of Soret and Dufour numbers on an unsteady MHD free convection of flow of heat and mass transfer through porous media. The substances and radiation along the viscous, incompressible, and conductive compounds respond to the unstable convection of the liquid. Using physical quantities, the dimensional governing equations are converted to non-dimensional equations. Finite element Galerkin method is applied to numerically solve the resulting partial differential equations. Flow parameters on velocity, temperature, and concentration are studied and explained graphically to reflect their effects. Similarly, the skin friction number and Nusselt number are also observed and recorded in tables.     

Synthesis of PVA/PVP based hydrogel for biomedical applications: a review

The composition and synthesis of hydrogel were developed by using Polyvinyl alcohol (PVA) and Polyvinylpyrrolidone (PVP). Polyvinyl alcohol (PVA) and Polyvinylpyrrolidone (PVP) based hydrogels are the most popular water-soluble, biodegradable, biocompatible, non-carcinogenic, and extremely low cytotoxicity synthetic polymers due to their good biocompatibility have been used in numerous biomedical applications, such as implants, artificial organs, drug delivery devices, and wound dressings. In this review paper, details of synthetic of hydrogel formulations with PVA and PVP for biomedical applications.     

Augmenting network lifetime for heterogenous WSN assisted IoT using mobile agent

Wireless Networks - Wireless sensor networks are network of the large number of sensors having lesser batteries. Such networks and clustering of the nodes for energy efficiency go hand in hand....     

An energy-efficient cuckoo search algorithm for virtual machine placement in cloud computing data centers

The Journal of Supercomputing - The advent of virtualization technology has created a huge potential application for cloud computing. In virtualization, a large hardware resource is often broken...     

Polymer production by bacterial strains isolated from activated sludge treating municipal wastewater.

Polyhydroxyalkanoates (PHAs) accumulating bacteria were isolated from activated sludge samples collected from municipal wastewater treatment plants in Quebec. Twelve bacterial strains were screened for PHA production with acetate as sole carbon source. PHA granules exhibited a strong orange fluorescence when stained with Nile blue A observed under microscope (X100x). PHA was also analyzed by Gas Chromatography Linked to Mass Spectroscopy (GCMS) to further confirm the presence and the concentration of PHA. To compare the abilities of these PHA accumulating bacterial strains, synthetic media with acetate as carbon source was prepared to accumulate PHA in 500 mL Erlenmeyer flask containing 150 of the medium. These flasks were then inoculated with the isolated bacterial strains, incubated at 25 degrees C for 48 hours in a rotary shaker at 220 rpm. The results showed that the bacterial strains isolated from sludge possess different abilities for accumulating PHA. The maximum PHA content of 27.50% was obtained by strain PHA-SB3. The PHB/PHV ratio of the copolymer produced in the study changed in accordance with operating time and strains.