Dry grinding kinetics of binary mixtures of ceramic raw materials by Bond milling

The kinetics of batch dry grinding of binary mixtures of ceramic raw materials, namely quartz–kaolin, quartz–potassium feldspar and kaolin–potassium feldspar, from the feed sizes of −3.350 + 2.360, −2.000 + 1.400, −0.850 + 0.600, −0.500 + 0.355 and −0.300 + 0.212 mm have been determined using a Bond mill with a mixture of ball sizes of 38.10, 31.75, 25.40, 19.05 and 12.70 mm diameter and total mass of 22.648 kg. The Bond mill used was a size of 30.5 cm diameter, 30.5 cm length, with a total volume of 22,272 cm³. The fractional ball filling was 22% of mill volume and the mill speed was 70 rpm. The breakage parameters were obtained for those mineral mixtures to predict the product size distributions. As the feed sized given above, which were ground in the mill, increase, the specific rate of breakage (S_i) values also increase, which means faster breakage with higher S_i value occurs in the order of quartz–kaolin, quartz–potassium feldspar and kaolin–potassium feldspar mixtures when comparing the characteristic values (slope of S_i versus size relationship with higher value). The cumulative breakage distribution function (B_i,j) values obtained for these mineral mixtures were slightly different in terms of the fineness factor, γ. This means that quartz–potassium feldspar mixture produced less fines with higher γ value, while kaolin–potassium feldspar gave more fines with lower γ value. The simulations of the product size distribution for these mixing were very close to the experimental data. Finally, slowing down effect, treated with false time concept, started earlier than the expected for these binary mixtures. There were some correlations found between the simulated time (θ) and experimental time (t).     

Local chill as a mean of increasing strength in grey cast iron

The influence of a chill on the mechanical properties and microstructural features in grey cast iron has been studied. Some of the main findings were that the chill refined the microstructure and modified the graphite distribution from A to D/E. Eutectic cell size was reduced by 60–70%. The Brinell hardness increased while the Vickers hardness, measured in dendrite arms, was unaffected. Fatigue testing in four point bending showed that the fatigue limit was increased by 20–30% in the chilled samples. An increase in tensile strength, proof strength and Young’s modulus was also observed in the chilled samples. The increase in fatigue limit was approximately twice as high as the increase in tensile strength. A possible explanation could be that the eutectic cell size had a more pronounced effect on the fatigue limit than on the tensile strength.     

Reduction of major peanut allergens Ara h 1 and Ara h 2, in roasted peanuts by ultrasound assisted enzymatic treatment

This study investigated the effects of ultrasound, enzyme concentration and enzyme treatment time on soluble protein and major allergenic proteins (Ara h 1 and Ara h 2) of roasted peanut kernels. A 3-factor, five-level orthogonal experimental design was implemented with various ultrasonication times, concentrations of trypsin or α-chymotrypsin and treatment times. The total soluble proteins were determined by the Bicinchoninic acid (BCA) method, Ara h 1 and Ara h 2 were evaluated by SDS–PAGE and sandwich ELISA. The IgE-binding of peanut extracts was analysed by a competitive inhibition ELISA. Results indicate that ultrasound treatment, followed by protease digestion of peanuts, significantly increased the solubility of peanut protein and decreased the concentrations of Ara h 1 and Ara h 2. The sequential treatment of peanuts by ultrasonication–trypsin–alpha chymotrypsin, resulted in maximum reductions of Ara h 1/Ara h 2, and lowest IgE-binding. This study provides an approach to significantly reduce allergenic proteins in peanut product.     

Properties and behavior of self-compacting concrete produced with GBFS and FA additives subjected to high temperatures

This paper presents an experimental investigation on the performance of self-compacting concrete (SCC) subjected to high temperatures. For this purpose, Portland cement was replaced with fly ash (FA) and granulated blast furnace slag (GBFS) in various proportions with and without polypropylene (PP) fibers and the PP fiber content was 2 kg/m³ for the mixtures that contained fibers. When the specimens were 56 days old, they were heated to elevated temperatures (200, 400, 600 or 800 °C). Afterword, tests were conducted to determine the weight loss and the compressive strength. Moreover, the change in the ultrasonic pulse velocity (UPV) was determined, and observations for surface cracks were made after the specimens were exposed to elevated temperatures. A severe strength loss was observed for all of the concretes after 600 °C, particularly for the concretes that contained PP fibers; however, the fibers reduced and eliminated the risk of explosive spalling. Based on the test results, it can be concluded that the performance of FA concrete is better than that of the GBFS concrete.     

Investigation of Boronizing Kinetics of AISI 51100 Steel

In this study, some mechanical properties of borided AISI 51100 steel with high C concentration were investigated. Boronizing heat treatment was carried out in solid medium consisting of Ekabor-II at 850, 900, and 950 °C for 2, 4, 6, and 8 h. Morphology and mechanical properties of boride layer, and the effect of chemical composition on properties and kinetics of borides were investigated. The results of this study indicated that the morphology of the boride layer has a saw-tooth nature, and its hardness is over 1500 HV. Depending on process time and temperature, the depth of boride layer ranged from 30 to 106 μm. Optical and SEM studies and XRD analysis revealed that borides formed on the surface of steel substrates have dominantly single Fe₂B boride phase in addition to small amount of Cr₂B.     

Extrusion parameters and consumer acceptability of a peanut-based meat analogue

Despite its high protein content and low cost, defatted peanut flour (DPF) remains underutilised in human foods. The objectives of this study were to: (1) determine the best extrusion parameters for a peanut-based textured meat analogue (TMA); (2) develop new TMA products from DPF and (3) evaluate their consumer acceptability. Preliminary runs using a wide range of extrusion parameters were conducted. A central composite RSM design was used to determine the optimal extrusion conditions within the best ranges revealed by the preliminary runs. Three levels of moisture, screw-speed and barrel temperature were used in 31 runs. Expansion ratio, bulk density, texture profile, water absorption/solubility indexes of the extrudates were determined and used as indicators of product quality. Peanut-based TMAs produced at optimal extrusion conditions were flavoured with beef flavour and evaluated by a 60-member sensory panel for flavour, texture, and overall liking, using a 9-point hedonic scale. Optimisation studies revealed that the most important extrusion conditions are in descending order: protein content, temperature, moisture and screw-speed. Extrusion conditions that produced the best TMA were 60–65% protein, 50–55% moisture, 160–165 °C and 80–90 r.p.m. Sensory acceptability of snacks incorporating peanut-based TMAs was similar or better than those containing soya-based TMAs in terms of flavour, texture, off-flavour and overall liking. TMA produced from inexpensive DPF has the potential to compete with commercial meat analogues, thereby adding value to the peanut industry.     

The use of nutshell carbons in drinking water filters for removal of chlorination by‐products

Chlorination of drinking water is a common practice, used by numerous municipalities in the United States (US) to safeguard their water supplies. However, the chlorine used can chemically react with organic components in the drinking water to produce unwanted chlorination by‐products. The objective of this investigation was to evaluate the use of granular activated carbon produced from nutshells (almond, English walnut, pecan) in a point‐of‐use (POU) water filtration system designated ‘Envirofilter’ and to determine its efficacy in removing select, potentially carcinogenic chlorination by‐products, namely the trihalomethanes (THMs) bromodichloromethane, bromoform and dibromochloromethane. The POU water filtration system that contained the nutshell‐based carbons was designated ‘Envirofilter’ and adsorption efficiencies of this system were compared to that of four commercially available POU home water filter systems, namely, BRITA, Omni Filter, PūR and Teledyne Water Pik. Eight different ‘Envirofilters’ were constructed of individual or binary mixtures of carbons produced from acid‐activated almond or pecan shells and steam‐activated pecan or walnut shells and evaluated for adsorption of the three chlorination by‐products. The results indicate that only two of the eight ‘Envirofilters’ failed to remove more THMs than the commercial POU systems. In both cases, these filters contained carbons with either 100% acid‐activated almond shells or 100% acid‐activated pecan shells. All six of the other filters contained carbons with either 50% or 100% steam‐activated pecan shells or steam‐activated walnut shells. Therefore, ‘Envirofilters’ appeared to depend on the presence of steam‐activated nutshell carbons for their success. The six effective ‘Envirofilters’ reduced THM levels to below the Maximum Contaminant Levels (MCL) required by the US Environmental Protection Agency (US EPA). Based on these results, these six ‘Envirofilters’ may be considered as a replacement for existing commercial filter systems because of their efficacy and projected cost. Copyright © 2004 Society of Chemical Industry     

Electrochromic behavior of poly(3,5-bis(4-bromophenyl)dithieno[3,2-b;2′,3′-d]thiophene)

Electropolymerization of 3,5-bis(4-bromophenyl)dithieno[3,2-b;2′,3′-d]thiophene, having a mild electron-withdrawing bromine atom attached to the para position of the two phenyl groups of dithienothiophene, was performed, utilizing a potentiodynamic method. The resultant homopolymer was characterized by cyclic volyammetry, fourier transform infrared and ultraviolet-visible spectroscopy. Spectroelectrochemical and electrochromic properties were investigated and a device was constructed with polyethylenedioxythiophene to understand the characteristics in detail, which had the potential range of 0.0-2.0 V for operating the device between green and blue colors. It had a good optical contrast of 18% with a switching time of less than a second. Moreover, open circuit memory and stability of the device were investigated.     

The effect of sintering temperature on some properties of Cu-SiC composite

Copper matrix composites reinforced with 1 wt.%, 2 wt.%, 3 wt.% and 5 wt.% SiC particles were fabricated by powder metallurgy method. Cu and Cu-SiC powder mixtures were compacted with a compressive force of 280 MPa and sintered in an open atmospheric furnace at 900-950 °C for 2 h. Within the furnace compacted samples were embedding into the graphite powder. The presence of Cu and SiC components in composites was verified by XRD analysis. Optical and SEM studies showed that Cu-SiC composites have a uniform microstructure in which silicon carbide particles are distributed uniformly in the copper matrix. The results of the study on mechanical and electrical conductivity properties of Cu-SiC composites indicated that with increasing SiC content (wt.%), hardness increased, but relative density and electrical conductivity decreased. The highest electrical conductivity of 98.8% IACS and relative density of 98.2% were obtained for the Cu-1 wt.%SiC composite sintered at 900 °C and this temperature was defined as the optimum sintering temperature.     

The effect of aromatic diboronic acid on characteristics of polybenzoxazine based on phenol and 4-aminomethylbenzoate

In this study, a polybenzoxazine, (PPab) based on phenol and 4-aminomethyl benzoate and its composites containing various amounts of 1,4-benzene diboronic acid, (BDBA) were synthesized by stepwise curing. It has been determined that both thermal stability and char yield were increased as the amount of BDBA incorporated was increased. The improvements in thermal characteristics were associated with condensation reactions of B-OH of BDBA and not only with hydroxyl groups of polybenzoxazine but also ester groups on the aniline linkages yielding a highly cross-linked structure. In addition, self-condensation reactions of B-OH groups generated boroxine net-work. Strong evidences for growth of this net-work on benzoate units of the polymer were detected.