Method of grinding as a factor in the rheological and technological properties of alumina suspensions

Conclusions Suspensions of alumina wet-ground and dry-ground in a ball mill are characterized by viscosity changes typical for firm systems with static {ie365-01} and dynamic (Bingham) {ie365-02} fluidity limits.These suspensions are thixotropic; the viscositygh _m of their fully broken up structure is higher and their zeta potential lower than for suspensions of vibro-ground alumina, the explanation being the considerably longer grinding time in a ball mill and the fact that in wet grinding a vigorous interaction proceeds between the solid and liquid phases directly in the grinding process.Alumina wet-ground in a ball mill contains more impurities after washing than alumina dry-ground in a vibro mill. The suspension of the former gives a faster rate of casting but the density and strength of the product are lower.Fired commercial alumina to be used for the production of high-quality dense-sintered refractory corundum ceramics should be dry-ground in a vibratory mill.Translated from Ogneupory, No. 6, pp. 44–51, June, 1977.     

Catalytic alcoholysis of quinolin-8-yl esters by manganese complexes

The role of different oxidation states of manganese in manganese(II) acetate promoted methanolysis reaction of p-nitrobenzoic acid quinolin-8-yl ester is presented.     

Simulation of transient thermal states in layered electronic microstructures

The analysis of dynamic temperature changes in microelectronic layered circuit (especially made in thick-film technology) has been presented in the paper. Such transient states are caused by electric pulse with high energy and short time of duration. It leads to short but the very violent temperature increase and - as result - defects or parameter changes of active layer. The mathematical function which describes the instantaneous temperature changes was presented in this paper in order to provide more accurate analysis of reliability and thermal properties measurement problems.The two-layer structures (with different thermo-physical properties) were the subject of conducted research, especially one of them, namely heat source excited by electric pulse. Such configuration is typical for microcircuits made in hybrid technology such as LTCC (low temperature co-fired ceramic), HTCC (high temperature co-fired ceramic) as well as thick - film technology in which polymer and photoimageable (photosensitive) materials are used.     

Recycling of Bakery Waste as an Alternative Carbon Source for Rhamnolipid Biosurfactant Production

Production of a rhamnolipid biosurfactant (RBS) using discarded mixed bakery waste (BW) employing bacterial strain Pseudomonas aeruginosa strain PG1 (identified by 16 s rDNA sequencing) was investigated for bioconversion of the food waste. Dry and powder form BW was supplemented with mineral salt media (MSM) as a sole carbon source for production of RBS. RBS production was measured based on the drop collapse assay and surface tension (ST) reduction of the culture media. Production of RBS in the culture media was enhanced by optimizing the carbon source (BW) concentration and the proper nitrogen source along with the pH of the MSM. Under optimized culture conditions, 11.56 g L⁻¹ day⁻¹ crude biosurfactant (BS) was achieved. The RBS had the ability to reduce the ST of the optimized MSM from 72.0 to 25.8 mN m⁻¹ during culture, where the critical micelle concentration (CMC) of the biosurfactant was found to be 100 mg L⁻¹. Liquid Chromatography Mass Spectroscopy (LC-MS), Fourier Transform Infrared spectroscopy (FTIR), and scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy (EDS) analyses of the purified BS confirmed that it is of rhamnolipid in nature and it is made up of both monorhamnolipid and dirhamnolipid congeners. Furthermore, the RBS did not express any cytotoxic effect on the cell line of mouse L292 fibroblastic cell indicating the biosafety nature of the high-value biomolecule.     

Comprehensive studies on polyethylenimine filled polypropylene and its potential application in carbon dioxide sequestration

Polypropylene (PP) was blended with branched polyethylenimine (PEI) with the aim to prepare blends having CO₂ adsorption property. The CO₂ adsorption properties will be conferred due to the presence of variety of amine functionality in PEI. PEI contains primary, secondary as well as tertiary amine groups. Before testing CO₂ adsorption, PP–PEI blends were characterized using variety of techniques, for example, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, scanning electron microscopy, and polarized light optical microscopy. In this work, we have studied in detail both compatibilized as well as noncompatibilized blends of PP and PEI. The compatibilization was achieved via addition of maleic anhydride grafted PP. Finally, all the compatibilized as well as noncompatibilized blends were studied for CO₂ adsorption. The compatibilized blends showed better thermal, mechanical as well as CO₂ adsorption properties as compared to the noncompatibilized blends. POLYM. ENG. SCI., 59:2092–2102, 2019. © 2019 Society of Plastics Engineers     

Sleepy keeper style based Low Power VLSI Architecture of a Viterbi Decoder applying for the Wireless LAN Operation sustainability

Analog Integrated Circuits and Signal Processing - Remarkable progress in the field of wireless communication has created a research interest for Viterbi decoder with long duration of battery life,...     

Effect of matrix content on the performance of carbon paper as an electrode for PEMFC

Porous conducting carbon fiber‐based composite paper is used as an electrode backing in the fuel cell assembly. It not only acts as a channel through which the reactant and product gases pass to and from the bipolar plate and the catalyst site but also helps in the flow of electrons. In order to perform its role efficiently, it should have sufficient strength, high electrical conductivity, and ideal porous structure. Carbon paper has been fabricated, which builds up the required composite properties. Studies have been conducted to optimize the fiber/matrix ratio in the carbon paper, while ensuring the perfect combination of porosity, mechanical strength, and electrical conductivity for an electrode in a proton electrolyte membrane fuel cells. Detail physico‐mechanical and electrochemical characterizations further ascertain that the fiber/matrix ratio plays an important role in tuning the composite properties. The polarization curve of the unit proton exchange membrane (PEM) fuel cell (with an effective electrode area 4 cm²) shows a peak power density of 916 mW/cm² for the sample with fiber/matrix ratio of 65:35, which is almost the same as the commercially available sigracet gas diffusion layer (SGL) carbon paper tested under similar conditions. Further, proportionally enlarging the electrode area to 100 cm² shows that the carbon paper not only shows almost repeatable results in a given set up but also scales up.