| 1. |
- Sharma, Pushpa Kumari, et al.
(författare)
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Adsorptive behavior of Fe/Zn-modified nanobiochar for arsenic removal from naturally contaminated groundwater
- 2023
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Ingår i: Groundwater for Sustainable Development. - : Elsevier BV. - 2352-801X. ; 23, s. 101011-
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Tidskriftsartikel (refereegranskat)abstract
- Global groundwater is frequently discovered to have high arsenic (As) concentrations, critically endangered and potentially toxic to aquatic organisms and humans. This work investigates As(V) adsorption using raw nanobiochar (RnBC) and activated magnetic nanobiochar (AMnBC), which are synthesized via pre-treating rice straw biomass with ZnCl2 and FeCl3 and pyrolyzing at 500 °C, followed by ball milling. The highest adsorption capacity for AMnBC and RnBC was 130 μg/g and 38.67 μg/g, respectively, at alkaline water chemistry to mimic natural groundwater conditions. Different functional groups contributed by modifications are evident with As(V) adsorption using RnBC and AMnBC. Multilayer chemisorption may explain the adsorption of As(V) on biochar surfaces, as Freundulich isotherm and pseudo-second-order kinetic model are suggested. The synthesis cost for AMnBC and RnBC was $0.0147/g and $0.0099/g, respectively, which helped to determine the most effective and efficient method for As(V) adsorption. In this study, natural As-contaminated groundwater collected from Patna, Bihar (India), was treated for As(V) removal using AMnBC in natural environments. Thus, this study recommends that cost-effective modified biochar can effectively be used for As(V) elimination from naturally contaminated groundwater as well as surface water.
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| 2. |
- Bera, Anup Kumar, et al.
(författare)
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Morphology induced large magnetic anisotropy in obliquely grown nanostructured thin film on nanopatterned substrate
- 2022
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 581
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Tidskriftsartikel (refereegranskat)abstract
- The artificial tailoring of magnetic anisotropy by manipulating surface and interface morphology is attracting widespread interest for its application in spintronic and magnetic memory devices. Here oblique angle deposition on a nanopatterned rippled substrate is presented as a novel route of inducing large in-plane uniaxial magnetic anisotropy (UMA) in magnetic thin films. For this purpose, Cobalt films and rippled SiO2 substrates have been taken as a model system for the present study. Here, nanopatterned substrates are prepared by low energy ion beam erosion (IBE), above which films are deposited obliquely along and normal to the ripple directions. A clear anisotropy in the growth behavior has been observed due to the inhomogeneous in-plane organization of adatoms in the form of columns. The increased shadowing effect in the films deposited obliquely normal to the direction of the ripple patterns causes preferential coalescence of the columns along the substrate ripples, resulting in stronger in-plane UMA in the film. This peculiarity in magnetic behavior is addressed by considering the morphological anisotropy governed by enhanced shadowing effect, the shape anisotropy and the dipolar interactions among the magnetostatically coupled ripple structure.
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| 3. |
- Bogaerts, Wim, et al.
(författare)
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Programmable Photonic Circuits powered by Silicon Photonic MEMS Technology
- 2022
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Ingår i: Photonic Networks and Devices, Networks 2022. - : Optica Publishing Group (formerly OSA).
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Konferensbidrag (refereegranskat)abstract
- Programmable photonic chips allow flexible reconfiguration of on-chip optical connections, controlled through electronics and software. We will present the recent progress of such complex photonic circuits powered by silicon photonic MEMS actuators.
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| 4. |
- Bogaerts, Wim, et al.
(författare)
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Programmable silicon photonic circuits powered by MEMS
- 2022
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE-Intl Soc Optical Eng.
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Konferensbidrag (refereegranskat)abstract
- We present our work to extend silicon photonics with MEMS actuators to enable low-power, large scale programmable photonic circuits. For this, we start from the existing iSiPP50G silicon photonics platform of IMEC, where we add free-standing movable waveguides using a few post-processing steps. This allows us to implement phase shifters and tunable couplers using electrostatically actuated MEMS, while at the same time maintaining all the original functionality of the silicon photonics platform. The MEMS devices are protected using a wafer-level sealing approach and interfaced with custom multi-channel driver and readout electronics.
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| 5. |
- Gupta, Pooja, et al.
(författare)
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Oblique angle deposited FeCo multilayered nanocolumnar structure : Magnetic anisotropy and its thermal stability in polycrystalline thin films
- 2022
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 590, s. 153056-
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Tidskriftsartikel (refereegranskat)abstract
- Iron-Cobalt (FeCo) columnar, multilayered structure is prepared by depositing several thin FeCo layers by varying the angle between the surface normal and the evaporation direction as 0 (normal) and 60(oblique), alternatively. In situ X-ray scattering and magneto-optical Kerr effect (MOKE) measurements established the evolution of magnetic properties with that of the morphology and structure of the multilayer. The strong shape anisotropy and compressive stress of nanocolumns in alternative FeCo layers resulted in a well-defined uniaxial magnetic anisotropy (UMA) with the easy axis of magnetization along the projection of the tilted nanocolumns in the film plane. The stress in the film provides minimization of magnetoelastic energy along the in-plane column direction, which couples with the columnar shape anisotropy energies and results in the preferential orientation of the magnetic easy axis along the oblique angle deposition direction in the film plane. Drastic reduction in the in-plane UMA after annealing at 450 C is attributed to the merging of columns and removal of stresses after heat treatment. The present study opens a new pathway to produce magnetically anisotropic multilayer structures using single material and thus may have prominent implications for future technological devices.
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| 6. |
- Khan, Umar, et al.
(författare)
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MORPHIC : MEMS enhanced silicon photonics for programmable photonics
- 2022
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Ingår i: Integrated Photonics Platforms Ii. - : SPIE-Intl Soc Optical Eng.
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Konferensbidrag (refereegranskat)abstract
- We present our work in the European project MORPHIC to extend an established silicon photonics platform with low-power and non-volatile micro-electromechanical (MEMS) actuators to demonstrate large-scale programmable photonic integrated circuits (PICs).
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| 7. |
- Nayak, Arun Kumar, et al.
(författare)
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A numerical and experimental study of water ingression phenomena in melt pool coolability
- 2009
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Ingår i: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 239:7, s. 1285-1293
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Tidskriftsartikel (refereegranskat)abstract
- During a postulated severe accident, the core can melt and the melt can fail the reactor vessel. Subsequently, the molten corium can be relocated in the containment cavity forming a melt pool. The melt pool can be flooded with water at the top for quenching it. However, the question that arises is to what extent the water can ingress in the corium melt pool to cool and quench it. To reveal that, a numerical study has been carried out using the computer code MELCOOL The code considers the heat transfer behaviour in axial and radial directions from the molten pool to the overlaying water, crust generation and growth, thermal stresses built-in the crust, disintegration of crust into debris, natural convection heat transfer in debris and water ingression into the debris bed. To validate the computer code, experiments were conducted in a facility named as core melt coolability (COMECO). The facility consists of a test section (200 mm x 200 mm square cross-section) and with a height of 300 mm. About 14 L of melt comprising of 30% CaO + 70% B2O3 (by wt.) was poured into the test section. The melt was heated by four heaters from outside the test section to simulate the decay heat of corium. The melt was water flooded from the top, and the depth of water pool was kept constant at around 700 mm throughout the experiment. The transient temperature behaviour in the melt pool at different axial and radial locations was measured with 24 K-type thermocouples and the steam flow rate was measured using a vortex flow meter. The melt temperature measurements indicated that water could ingress only up to a certain depth into the melt pool. The MELCOOL predictions were compared with the test data for the temperature distribution inside the molten pool. The code was found to simulate the quenching behaviour and depth of water ingression quite well.
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| 8. |
- Bogaerts, Wim, et al.
(författare)
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Scaling programmable silicon photonics circuits
- 2023
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Ingår i: Silicon Photonics XVIII. - : SPIE-Intl Soc Optical Eng.
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Konferensbidrag (refereegranskat)abstract
- We give an overview the progress of our work in silicon photonic programmable circuits, covering the techn stack from the photonic chip over the driver electronics, packaging technologies all the way to the sof layers. On the photonic side, we show our recent results in large-scale silicon photonic circuits with diff tuning technologies, including heaters, MEMS and liquid crystals, and their respective electronic driving sch We look into the scaling potential of these different technologies as the number of tunable elements in a ci increases. Finally, we elaborate on the software routines for routing and filter synthesis to enable the pho programmer.
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| 9. |
- Jo, Gaehun, 1992-, et al.
(författare)
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Wafer-level Hermetic Sealing of Silicon Photonic MEMS by Direct Metal-to-Metal Bonding
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The field of silicon (Si) photonic micro-electromechanical system (MEMS) for photonic integrated circuits (PICs) has evolved rapidly. Thanks to the ultra-low power consumption of Si photonic MEMS, it enables a wide range of high-performance photonic devices such as integrated optical MEMS phase shifters, tunable couplers and switches. However, photonic MEMS have suspended and movable parts which need to be protected from environmental influences, such as exposure to dust and humidity. Therefore, a packaging solution is needed for reliable operation over long periods. Here, we demonstrate wafer-level vacuum sealing of Si photonic MEMS inside cavities with ultra-thin Si caps.
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| 10. |
- Khan, Umar, et al.
(författare)
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Low power actuators for programmable photonic processors
- 2023
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Ingår i: AI and Optical Data Sciences IV. - : SPIE-Intl Soc Optical Eng.
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Konferensbidrag (refereegranskat)abstract
- The demand for efficient actuators in photonics has peaked with increasing popularity for large-scale general-purpose programmable photonics circuits. We present our work to enhance an established silicon photonics platform with low-power micro-electromechanical (MEMS) and liquid crystal (LC) actuators to enable large-scale programmable photonic integrated circuits (PICs).
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