A computational analysis of the impact of mass transport and shear on three-dimensional stem cell cultures in perfused micro-bioreactors

In this study, Computational Fluid Dynamics(CFD) is used to investigate and compare the impact of bioreactor parameters(such as its geometry, medium flow-rate, scaffold configuration) on the local transport phenomena and, hence, their impact on human mesenchymal stem cell(hM SC) expansion. The geometric characteristics of the TissueFlex174;(Zyoxel Limited, Oxford, UK) microbioreactor were considered to set up a virtual bioreactor containing alginate(in both slab and bead configuration) scaffolds. The bioreactor and scaffolds were seeded with cells that were modelled as glucose consuming entities. The widely used glucose medium, Dulbecco's Modified Eagle Medium(DMEM), supplied at two inlet flow rates of 25 and 100 μl·h~(-1), was modelled as the fluid phase inside the bioreactors. The investigation, based on applying dimensional analysis to this problem, as well as on detailed three-dimensional transient CFD results, revealed that the default bioreactor design and boundary conditions led to internal and external glucose transport, as well as shear stresses, that are conducive to h MSC growth and expansion. Furthermore, results indicated that the ‘top-inout' design(as opposed to its symmetric counterpart) led to higher shear stress for the same media inlet rate(25 μl·h~(-1)), a feature that can be easily exploited to induce shear-dependent differentiation. These findings further confirm the suitability of CFD as a robust design tool.     

Formation of Ferroelectric Phases in Sb–S–I Glasses

We have investigated devitrification of glasses within infrared transmitting xSbSI–(100 ? x)Sb₂S₃ pseudo‐binary series, which forms SbSI and Sb₂S₃ ferroelectric crystal phases. Differential scanning calorimetry (DSC) and X‐ray powder diffraction results show unusual behavior for the formation of the SbSI phase, which occurs by two parallel processes: one‐dimensional crystallization at low temperature which starts from the sample surface, and three‐dimensional bulk crystallization that continues the transformation to crystalline state at higher temperatures. The ratio of the intensities of the high‐temperature exothermal peak to the low‐temperature peak in DSC scans increases as the particle size and heating rate are increased. In contrast to the SbSI phase, the temperature of crystallization for the Sb₂S₃ phase does not depend on the particle size. Models are proposed for the origin of the various crystallization mechanisms.     

Application of modified pyrolytic graphite electrode as a sensor in the simultaneous assay of adenine and adenosine monophosphate

A simple and sensitive method based on square wave voltammetry (SWV) at single-walled carbon nanotube (SWNT) modified edge plane pyrolytic graphite electrode (EPPGE) is proposed for the simultaneous determination of adenine and adenosine-5′-monophosphate (5′-AMP). The modified electrode exhibits remarkable electrocatalytic properties towards adenine and 5′-AMP oxidation with a peak potential of ∼850 and 1165 mV respectively. Linear calibration curves are obtained over the concentration range of 5-100 nM for adenine and 10-100 nM for 5′-AMP with sensitivity of 677 and 476 nA nM⁻¹ for adenine and 5′-AMP respectively. The limit of detection for adenine and 5′-AMP was found to be 37 × 10⁻¹⁰ M and 76 × 10⁻¹⁰ M, respectively. The effect of pH revealed that the oxidation of adenine and 5′-AMP at SWNT modified EPPGE involved equal number of electrons and protons. The modified electrode exhibited high stability and reproducibility.     

Effects of helical GNF on improving the dehydrogenation behavior of LiMg(AlH4)3 and LiAlH4

The present paper reports the effect of graphitic nanofibres (GNFs) for improving the desorption kinetics of LiMg(AlH₄)₃ and LiAlH₄. LiMg(AlH₄)₃ has been synthesized by mechano-chemical metathesis reaction involving LiAlH₄ and MgCl₂. The enhancement in dehydrogenation characteristics of LiMg(AlH₄)₃ has been shown to be higher when graphitic nanofibres (GNFs) were used as catalyst. Out of two different types of nanofibres namely planar graphitic nanofibre (PGNF) and helical graphitic nanofibre (HGNF), the latter has been found to act as better catalyst. We observed that helical morphology of fibres improves the desorption kinetics and decreases the desorption temperature of both LiMg(AlH₄)₃ and LiAlH₄. The desorption temperature for 8 mol% HGNF admixed LiAlH₄ gets lowered from 159 °C to 128 °C with significantly faster kinetics. In 8 mol% HGNF admixed LiMg(AlH₄)₃ sample, the desorption temperature gets lowered from 105 °C to ∼70 °C. The activation energy calculated for the first step decomposition of LiAlH₄ admixed with 8 mol% HGNF is ∼68 kJ/mol, where as that for pristine LiAlH₄ it is 107 kJ/mol. The activation energy calculated for as synthesized LiMg(AlH₄)₃ is ∼66 kJ/mol. Since the first step decomposition of LiMg(AlH₄)₃ occurs during GNF admixing, the activation energy for initial step decomposition of GNF admixed LiMg(AlH₄)₃ could not be estimated.     

Plastic fats and margarines through fractionation,blending and interesterification of milk fat

Milk fat stearins and oleins were blended with high‐ and low‐melting natural fats to produce plastic fats, vanaspati substitute and confectionery fats. Margarines of improved nutritional value were also formulated. Fractionation was carried out using acetone, hexane, and isopropyl alcohol. The yield (wt‐%) of high‐melting stearin (HMS) from acetone and IPA was 13.0 ± 0.2 to 13.3 ± 0.1 after crystallization for 24 h at 20 °C. The melting point of the products was 49.0 ± 0.5 to 49.8 ± 0.6 °C. However, in hexane the yield of HMS was 12.2 ± 0.2% at 10 °C. The olein fractions were further fractionated at 10 °C from acetone and IPA, and at 0 °C from hexane, to obtain superoleins and low‐melting stearins (LMS). HMS fractions were blended with rice bran oil and cottonseed oil at the ratio 70 : 30 (wt/wt), and the superoleins were blended with sal fat and palm stearin at the ratios 40 : 60, 30 : 70 and 20 : 80 (wt/wt). The blends were interesterified (product melting point: 22.7 ± 0.04 to 39.3 ± 0.10 °C) chemically and enzymatically to prepare margarine. The penetration values (in 0.1 mm) of these margarines were noted to be 112 ± 1.52 to 145 ± 0.00.     

A new clustering method for the diagnosis of CoVID19 using medical images

Applied Intelligence - With the spread of COVID-19, there is an urgent need for a fast and reliable diagnostic aid. For the same, literature has witnessed that medical imaging plays a vital role,...     

Experimental investigation of ice‐chamber for melting of ice based on Scheffler solar concentrator for high altitude regions

This experimental analysis was performed with the aim to melt the ice into hot water at very high altitude regions such as Leh Ladakh. Three different designs of ice‐chamber were used to melt the ice with direct heating in minimum time. The radiations were focused on the receiver with the help of 1 m² Scheffler solar concentrator exposed to the atmospheric situations of NIT Kurukshetra. The Scheffler solar concentrator was fabricated with fiber‐reinforced plastic material. The fabrication process is discussed in detail. The results obtained from the design showed that the ice frozen at ?5°C completely melted, converting into water. The maximum temperature of water attained in the ice‐chamber with receiver 1 (circular plate with fins), 2 (CPC with fins), and 3 (copper crucible) was 57.7°C, 64.3°C, and 67.4°C, respectively.