| 1. |
- Mukherjee, Subhankar, et al.
(författare)
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Sensory development for heavy metal detection: A review on translation from conventional analysis to field-portable sensor
- 2021
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Ingår i: Trends in Food Science & Technology. - : ELSEVIER SCIENCE LONDON. - 0924-2244 .- 1879-3053. ; 109, s. 674-689
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Forskningsöversikt (refereegranskat)abstract
- Background: In recent decades, contaminations with heavy metals ions have adversely affected the environment, food safety, and human health. Heavy metals, leaching to water sources from the industrial effluents, can enter into the aquatic and food chains of humans and animals from a variety of anthmpogenic sources. Scope and Approach: Heavy metal detection has been an intensive area of research today. Both laboratory-based analytical instruments and innovative sensor devices like the electronic nose, electronic tongue, and bio/ chemical sensors have increasingly emerged to meet the demand for legislative actions on environmental pollution control and early warning. These evolving technology and developments particularly in the area of nanotechnology and sensors have become key contributing factors in heavy metal detection. Key Findings and Conclusions: This endeavor aims at exploring this field in detail to understand the key principles behind this flourishing science and summarize the recent development in heavy metal detection technologies. This article also gives a brief review of commercially available portable devices that has the potential to become the next gold standard instruments in heavy metal detection.
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| 2. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 3. |
- Ghosh, Souvik, et al.
(författare)
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Modal and non-modal linear stability of Poiseuille flow through a channel with a porous substrate
- 2019
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Ingår i: European journal of mechanics. B, Fluids. - : Elsevier. - 0997-7546 .- 1873-7390. ; 75, s. 29-43
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Tidskriftsartikel (refereegranskat)abstract
- We present modal and non-modal linear stability analyses of Poiseuille flow through a plane channel with a porous substrate modeled using the Volume Averaged Navier-Stokes (VANS) equations. Modal stability analysis shows the destabilization of the flow with increasing porosity of the layer. The instability mode originates from the homogeneous fluid region of the channel for all the values of porosity considered but the governing mechanism changes. Perturbation kinetic energy analysis reveals the importance of viscous dissipation at low porosity values while dissipation in the porous substrate becomes significant at higher porosity. Scaling analysis highlights the invariance of the critical wavenumber with changing porosity. On the other hand, the critical Reynolds number remains invariant at low porosity and scales as Re-c similar to (H/delta)(1.4) at high porosity where delta is the typical thickness of the vorticity layer at the fluid-porous interface. This reveals the existence of a Tollmien-Schlichting-like viscous instability mechanism at low porosity values, and Rayleigh analysis shows the presence of an inviscid instability mechanism at high porosity. For the whole range of porosities considered, the non-modal analysis shows that the optimal mechanism responsible for transient energy amplification is the lift-up effect, giving rise to streaky structure as in single-phase plane Poiseuille flow. The present results strongly suggest that the transition to turbulence follows the same path as that of classical Poiseuille flow at low porosity values, while it is dictated by the modal instability for high porosity values. SAS. All rights reserved.
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| 4. |
- Paul, Souvik, et al.
(författare)
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Anti-site disorder and improved functionality of Mn2NiX (X = Al, Ga, In, Sn) inverse Heusler alloys
- 2014
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 116:13, s. 133903-
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Tidskriftsartikel (refereegranskat)abstract
- Recent first-principles calculations have predicted Mn2NiX (X = Al, Ga, In, Sn) alloys to be magnetic shape memory alloys. Moreover, experiments on Mn2NiGa and Mn2NiSn suggest that the alloys deviate from the perfect inverse Heusler arrangement and that there is chemical disorder at the sublattices with tetrahedral symmetry. In this work, we investigate the effects of such chemical disorder on phase stabilities and magnetic properties using first-principles electronic structure methods. We find that except Mn2NiAl, all other alloys show signatures of martensitic transformations in presence of anti-site disorder at the sublattices with tetrahedral symmetry. This improves the possibilities of realizing martensitic transformations at relatively low fields and the possibilities of obtaining significantly large inverse magneto-caloric effects, in comparison to perfect inverse Heusler arrangement of atoms. We analyze the origin of such improvements in functional properties by investigating electronic structures and magnetic exchange interactions.
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| 5. |
- Paul, Souvik, et al.
(författare)
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First-principles study of the lattice instabilities in Mn2NiX (X = Al, Ga, In, Sn) magnetic shape memory alloys
- 2015
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 27:3, s. 035401-
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Tidskriftsartikel (refereegranskat)abstract
- Using first-principles based density functional theory, we have investigated the structural instabilities in the austenite phases of Mn2NiX (X = Al, Ga, In, Sn) magnetic shape memory alloys. A complete softening is observed in the acoustic TA(2) branches for all the materials along [xi xi 0] directions leading to instability in the austenite structure which effectively stabilizes into martensitic structure. The reasons behind this softening are traced back to the repulsion from the optical T-2g branches and to the nesting features in the Fermi surfaces. The vibrational density of states, the force constants and the elastic moduli are also computed and analyzed, which reconfirm the underlying mechanism behind the instabilities. The results indicate that the phonon anomalies are related to the occurrence of possible pre-martensitic phases which can be quite complex.
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| 6. |
- Paul, Souvik, et al.
(författare)
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Magnetic properties of Mn2NiSn shape memory alloy
- 2013
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 25:23, s. 236005-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the magnetic properties of the inverse Heusler Mn2NiSn alloy computed by ab initio density functional theory (DFT) calculations in order to understand the large magnetic moments observed in experiments in contrast to smaller values obtained in previous ab initio calculations. Our results show that the magnetization in this system is quite sensitive to volume and atomic ordering in the sublattices. The observed variations in the magnetizations are explained from the features in the electronic structures of the Mn d-bands. We conclude that the symmetry of lattice sites and the alloying with Ni atoms are responsible for a high magnetic moment for a range of volumes. This opens a possible route to realize a large magnetization, a requirement for shape memory properties in magnetic alloys, in similar systems with an inverse Heusler structure.
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