Formulation of a physically motivated specific breakage rate parameter for ball milling via the discrete element method

A physically based specific breakage rate parameter of the population balance model for batch dry‐milling is formulated, which explicitly accounts for the impact energy distribution calculated by the discrete element method (DEM). Preliminary DEM simulations of particle impact tests were first performed, which concluded that dissipation energy should be used in contrast to collision energy to accurately define the impact energy distribution. Subsequently, DEM simulations of the motion of spheres representing silica glass beads in a ball mill were performed to determine the specific breakage rate parameter, which was in good agreement with those found experimentally. An analysis of the impact energy distribution, which was only possible within context of the physically motivated specific breakage rate parameter, emphasized the importance of accounting for a threshold impact energy. Without proper assessment of the impact energy distribution, DEM simulations may lead to an erroneous evaluation of milling experiments. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2404–2415, 2014     

Comparison of HPLC and GLC methodologies for determination of glucosinolates using reference material

 The reference material rapeseed of known glucosinolate composition, was analysed by HPLC and GLC and two commercially available glucosinolates (glucotropaeolin and sinigrin) were used as internal standards. The HPLC method enabled determination of 11 different glucosinolates (as desulphoglucosinolates) that occur in the rapeseed. Only seven glucosinolates (as trimethylsilylated desulphoglucosinolates) were separated by GLC. The latter method did not allow the determination of methylsulphinylalkyl glucosinolates (glucoiberin, glucoraphanin and glucoallysin) and did not separate optical isomers of 2-hydroxy-3-butenyl glucosinolate (progoitrin and epi-progoitrin). Statistical evaluation of data (t-test, F-test) revealed no significant differences between the tested methods at the 95% confidence level. The advantages and disadvantages of both widely used chromatographic methods are discussed. Received: 26 May 1997 / Revised version: 11 July 1997     

Formation of volatile compounds and brown products in the model system n-hexanal-glycine.

During the boiling of a mixture of n-hexanal and glycine in aqueous medium, pH value 9, both soluble and insoluble brown colored pigments and volatile compounds were formed. The following volatile compounds were identified by gas chromatography and mass spectrometry; hexanone, decenone, undecenone, undecan-5-one, undecenedione, dodecenone, tridecanone, dodecanedione, tridecenone, dodecenedione, hexenyl hexanoate, caproic, valeric and butyric acids. The brown coloured pigments insoluble in water contained 0.57% of nitrogen. The presence of conjugated double-bonds, carbonyl and carboxyl groups was confirmed by spectral methods. The pigments were also separated by thin-layer chromatography on silica gel.     

Decomposition of sinigrin by methanol/ammonia/water treatment in model systems and mustard (Brassica nigra L.) seed meal

 Sinigrin (allylglucosinolate) was stored at 20  °C, 40  °C, and 60  °C in solutions containing 10% ammonia in 95% methanol (CH₃OH/NH₃/H₂O). The individual samples were analyzed for their contents of sinigrin, its decomposition product allyl isothiocyanate (AITC) and other reaction products. The major reaction products were allyl thiourea, methyl ester of N-allyl thiocarbamoyl acid and allyl cyanide. A newly identified decomposition product of sinigrin was ethylcyanide. Defatted Brassica nigra seed meal was treated by the CH₃OH/NH₃/H₂O mixture to simulate the procedure used for rape and mustard seed meal detoxification. suspensions of the meal in the above mixture of solvents were heated at 20  °C, 40  °C and 60  °C, respectively. The major reaction products were the same as those arising from sinigrin. Minor products identified were 4-hydroxybenzyl isothiocyanate formed from sinalbin and 2-hydroxy-butenyl cyanide which arises from progoitrin. In all cases, AITC was very rapidly decomposed. Mechanisms explaining sinigrin decomposition are presented and discussed. Received: 3 May 1999     

Dynamic simulation of particle packing influenced by size, aspect ratio and surface energy

The multi-sphere method and JKR model are used in the discrete element method simulation to investigate the effect of the particle size, aspect ratios, and cohesiveness on the packing structure, characterized by porosity, radial distribution function (RDF), coordination number and contact geometry. In the absence of cohesive force, the porosity is nearly invariable with fixed aspect ratio, regardless of the size of the particles. In contrast, as surface energy increases, the porosity increases with decreasing particle size and increasing aspect ratio. The RDF results show that the number of peaks for different aspect ratios changes and show trends similar to the relaxation algorithm, expected for the finer particles. In the case of finer, cohesive particles, the most novel outcome of contact analysis is the existence of single contact, attributed to the formation of a cage structure, which has not been previously reported. The peak position and the width of the contact distributions are affected by higher surface energy because fewer contacts are required to achieve the mechanical equilibrium. Another interesting observation is that higher porosity does not always imply fewer contacts for particles with non-zero aspect ratios and high surface energies. The analysis of the distribution of the contact vector angles is found to better explain increased porosity in spite of higher coordination numbers. The results presented shed light on the packing density and structure, revealing features not easily discerned via experiments, and confirming the important role of the cohesion and aspect ratio in packing.     

Breathable,Flexible, Transparent,Hydrophobic, and Biotic Sustainable Electrodes for Heating and Biopotential Signal Measurement Applications

Pressure to reduce the global amount of e-waste has increased in recent years. The optimal use of natural resources is a demanding area especially due to the overabundance of the use of resources and challenges with after-life disposal. Herein, an easy method is developed to fabricate an improved version of leaf skeleton-based biodegradable, transparent, flexible, and hydrophobic electrodes. A fractal-like rubber leaf skeleton is used as the substrate, physical vapor deposited Au interlayer to promote adhesion, and uniform deposition of overlayer silver nanowires. The fabricated surfaces present a high level of electrical stability, optical transparency, hydrophobicity, and robust mechanical properties. The prepared electrodes demonstrate a comparable level of optical transmittance to the virgin leaf skeleton. The mechanical sturdiness of the electrodes is verified by 1k bending cycles. To demonstrate the functionality of these hybrid biotic conductive network (HBCN) electrodes, their performance is evaluated as flexible transparent heating elements and as biosignal measurement electrodes. The heater can reach a temperature of 140 °C with only 2.5 V in ≈5 s and Ag nanowire loading of ≈160 μg cm⁻². Likewise, electrocardiogram (ECG) and electromyogram (EMG) signals are successfully obtained from the electrodes without using any electrode gel or other electrolytes.