74 research outputs found
Fabrication of bismuth ferrite based hybrid nanostructures: Insight into a catalytic and sensing properties for the detection of biomolecules
No full textSunlight driven photocatalytic water splitting using nanostructured bismuth tungstate (Bi2WO6)
No full textDesign, Development and Characterization of Variable Reluctance Ferrofluid Pump
No full textFerrofluids are stable colloidal homogeneous mixtures of nano-size single-domain ferromag¬netic particles covered by surfactant layer, and suspended in a carrier fluid compatible with the surfactant. Physical properties of ferrofluid allows one to control it externally using magnetic field without being in direct contact with it. The thesis presents a novel mechanism to pump ferrofluid based on the principle of variable reluctance, in an external magnetic field.
The static and dynamic pressure behavior of ferrofluid in a switched DC magnetic field gives an insight into the variable reluctance behavior of ferrofluid. A ferrofluid pump based on the prin¬ciple of variable reluctance of ferrofluid subjected to an external magnetic field, is developed and hence the pump is named as Variable Reluctance Ferrofluid Pump (VRFP).
Three configurations of VRFP are developed:
• Single stage one-phase VRFP
• Single stage two phase VRFP
• Multi-stage VRFP
A one-phase VRFP consisting of a check valve along with an electromagnet is designed. The valve is modeled and its transfer function is estimated using System Identification method. This model is then used in the simulation model of the pump. The pump is modeled based on the hydraulic-electric analogies. An electric circuit which represents the gross level equivalent of the pump is simulated and the results are compared with that of the experimental measurements.
A two phase VRFP is implemented with two electromagnets on either side of the valve around the tube. Two types of magnetic actuation methods are introduced based on the switching sequences of the two electromagnets, namely Full Step Sequencing and Half Step Sequencing. Simulations and experiments were conducted for different pumping conditions.
The one phase and two phase VRFPs are single stage structures. A multi-stage VRFP concept, in which the ferrofluid flow channel (tube) is looped through the electromagnets multiple times, is introduced. For the implementation purpose, a two-stage VRFP is discussed in this thesis. Simulations and experiments resulted in significant improvement in case of two-stage VRFP in the pump performance compared to that of single-stage VRFPs.
The work presents a simple and novel design of a ferrofluid pump, which is capable of higher flow rates and pumping against higher back pressure compared to the ferrofluid pumps reported in literature.
Keywords: Ferrofluid Pump, VRFP, Variable Reluctance, Multi Stage, Magnetic Fluid
Street Scene Video Anomaly Detection Dataset
No full text<p><strong><span>Introduction</span></strong></p>
<p><span>The Street Scene dataset consists of 46 training video sequences and 35 testing video sequences taken from a static USB camera looking down on a scene of a two-lane street with bike lanes and pedestrian sidewalks.<span> </span>Videos were collected from the camera at various times during two consecutive summers.<span> </span>All of the videos were taken during the daytime.<span> </span>The dataset is challenging because of the variety of activities taking place such as cars driving, turning, stopping and parking; pedestrians walking, jogging and pushing strollers; and bikers riding in bike lanes. In addition, the videos contain changing shadows, and moving background such as a flag and trees blowing in the wind.</span></p>
<p><span>There are a total of 202,545 color video frames (56,135 for training and 146,410 for testing) each of size 1280 x 720 pixels. The frames were extracted from the original videos at 15 frames per second.</span></p>
<p><span>The 35 testing sequences have a total of 205 anomalous events consisting of 17 different anomaly types. A complete list of anomaly types and the number of each in the test set can be found in our paper.</span></p>
<p><span>Ground truth annotations are provided for each testing video in the form of bounding boxes around each anomalous event in each frame. Each bounding box is also labeled with a track number, meaning each anomalous event is labeled as a track of bounding boxes. Track lengths vary from tens of frames to 5200 which is the length of the longest testing sequence. A single frame can have more than one anomaly labeled.</span></p>
<p><span>NOTE: This version of the dataset differs slightly with the original made available in 2020.<span> </span>Some anomalies were found in a few of the normal training sequences.<span> </span>These training frames were deleted from the dataset.<span> </span>Specifically, the following frames were removed:</span></p>
<p><span>Train026: frames 1-184 (car taking a u-turn)</span></p>
<p><span>Train027: frames 1-229 (jay walkers)</span></p>
<p><span>Train031: frames 1-299 (jay walkers, illegally parked car)</span></p>
<p><strong><span>At a Glance</span></strong></p>
<ul>
<li><span>The size of the unzipped dataset is ~46GB</span></li>
<li><span>The dataset consists of Train sequences (containing only videos with normal activity), Test sequences (containing some anomalous activity) along with ground truth annotations, and a README.md file describing the data organization and ground truth annotation format.</span></li>
<li><span>The zip file contains a Train directory, a Test directory and a README.md file.</span></li>
</ul>
<p><strong><span>Other Resources</span></strong></p>
<p><span>None</span></p>
<p><strong><span>Citation</span></strong></p>
<p><span>If you use the Street Scene dataset in your research, please cite our contribution:</span></p>
<pre><code>@inproceedings{ramachandra2020street,
title={Street Scene: A new dataset and evaluation protocol for video anomaly detection},
author={Ramachandra, Bharathkumar and Jones, Michael},
booktitle={Proceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision},
pages={2569--2578},
year={2020}
}
</code></pre>
<p><strong><span>License</span></strong></p>
<p><span>The Street Scene dataset is released under </span><a href="https://creativecommons.org/licenses/by-sa/4.0/"><span>CC-BY-SA-4.0 license</span></a><span>.</span></p>
<p><span>All data:</span></p>
<pre><code>Created by Mitsubishi Electric Research Laboratories (MERL), 2023
SPDX-License-Identifier: CC-BY-SA-4.0
</code></pre>
Design, development and characterization of variable reluctance ferrofluid pump
No full textThe objective of this paper is to design and implement a ferrofluid pump actuated by switched magnetic field. The pump works on the principle of variable reluctance behavior of ferrofluid in an external magnetic field. A brief experiment to understand dynamic nature of magnetic flux density in a ferrofluid column is conducted. Variable reluctance phenomenon in the ferrofluid column is analyzed. Design and implementation details of two different structures of ferrofluid pump are discussed, namely single phase pump and two phase pump. Equivalent electrical circuit models of the pumps are developed based on hydraulic-electric analogy. Simulations and experiments are conducted and the results are compared. The designed pump is capable of pumping the ferrofluid at a rate of 84 A mu l/s with zero discharge head and a maximum flow rate of 56 A mu l/s is achieved with a discharge head of 120 mm
The Design and Synthesis of Cathode Materials for High-Performance Li-S Batteries
No full textAmong different rechargeable batteries, Li-S batteries (LSBs) are considered as the potential alternative to Li-ion batteries (LIBs) due to their high theoretical capacity (1675 mA h g-1) and energy density (2600 W h kg-1). Furthermore, sulfur is inexpensive and available in abundance compared to the commercial mixed metal oxide and olivine type (LiFePO4) cathodes which are being used in commercial LIBs whose energy density is also limited to 200 W h kg-1. However, the commercialization of LSBs is hindered by some of the fundamental challenges such as polysulfide dissolution and shuttle, sluggish conversion kinetics of polysulfides and volume expansion during the charge-discharge process in LSBs. These result in poor cycle life and Coulombic Efficiency (C.E.) of the batteries. This thesis investigates different sulfur host materials to address these issues with the aim to improve the cycle life of LSBs. Towards this objective, firstly, a nickel (II) phthalocyanine tetra sulfonate crosslinked polypyrrole was used as a sulfur host where the Ni2+ displayed strong electrostatic polyvalent interactions with LiPS intermediates and improved the performance of LSBs with a stable performance over 500 charge-discharge cycles. Furthermore, density functional theory (DFT) studies revealed strong interactions with different polysulfides which further supported the improved electro-chemical performance. Further, two organic redox-active small molecules based on diketopyrrolopyrrole (DPP) were synthesized with phenyl and pyridine substituents. The pyridine substituted DPP (PyDPP) possessed higher adsorption energy for lithium polysulfides due to the strong pyridinic N-Li interactions which also amplified the adsorption energy of carbonyl oxygen of DPP compared to that of phenyl DPP (PhDPP). Thus, LSBs with PyDPP outperformed PhDPP comprising batteries in terms of specific capacity, rate performance and long-term cycling stability. Also, the band edges of the radical anions of PyDPP and PhDPP are commensurate for efficient charge transfer with Li2S thus improving the sulfur utilization. Subsequently, a series of porous organic polymers (POPs) was synthesized with different functional moieties (acetylene, carbonyl and pyridine) to impart chemisorption for polysulfides and improve the electrocatalysis. Interestingly, the polymers possess similar pore size distributions which match the size of polysulfides, thus imparting physicochemical confinement for polysulfides and improving the cycling life of the LSBs with POPs. Among the four polymers, the polymer with both carbonyl and pyridinic N displayed the best performance with capacity close to 1000 mA h g-1 at 1C with stable performance over 600 cycles which is attributed to multiple polysulfide interacting groups which also improved their electrocatalysis. DFT studies also revealed the strong interactions between the polysulfides, and the functional moieties present in the POPs. Finally, the thesis summarizes the research findings and future directions for further advancement in the field of LSBs and their potential applications.</p
N-substituted pyrido-1,4-Oxazin-3-ones induce apoptosis of hepatocellular carcinoma cells by targeting NF-κB signaling pathway
No full textHepatocellular carcinoma (HCC) is a fatal disease and ranked fifth in cancer related mortality. Persistent activation of NF-κB is responsible for the oncogenesis, metastasis, tumor evasion, anti-apoptosis, angiogenesis and proliferation in HCC. Therefore, designing of chemically novel, biologically potent small molecules that target NF-κB signaling cascade have gained prominent clinical interest. Herein we synthesized a novel class of 4-(substituted)-2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one by reacting 2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one with various alkyl halides by using combustion derived bismuth oxide. We evaluated the antiproliferative efficacy of newly synthesized compounds against HCC cells and identified 4-(4-nitrobenzyl)-2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one (NPO) as lead anticancer agent. In addition, we investigated the effect of NPO on the DNA binding ability of NF-κB and NF-κB regulated luciferase expression in HCC cells. The results demonstrated that NPO can induce significant growth inhibitory effects in HepG2, HCCLM3 and Huh-7 cells in dose and time-dependent manner. Interestingly, NPO induced significant downregulation in p65 DNA binding ability, p65 phosphorylation and subsequent expression of NF-κB dependent luciferase gene expression in diverse HCC cell lines. Further, in silico docking analysis suggested that NPO can show direct physical interaction with NF-κB. Finally, NPO was found to significantly abrogate tumor growth at a dose of 50 mg/kg in an orthotopic mouse model. Thus, we report the potential anticancer effects of NPO as a novel inhibitor of NF-κB signaling pathway in HCC. Copyright © 2018 Mohan, Bharathkumar, Dukanya, Rangappa, Shanmugam
Novel benzoxazine-based aglycones block glucose uptake in vivo by inhibiting glycosidases
No full textGlycoside hydrolases catalyze the selective hydrolysis of glycosidic bonds in oligosaccharides, polysaccharides, and their conjugates. β-glucosidases occur in all domains of living organisms and constitute a major group among glycoside hydrolases. On the other hand, the benzoxazinoids occur in living systems and act as stable β-glucosides, such as 2-(2,4-dihydroxy-7-methoxy- 2H-1,4-benzoxazin-3(4H)-one)-β-D-gluco-pyranose, which hydrolyse to an aglycone DIMBOA. Here, we synthesized the library of novel 1,3-benzoxazine scaffold based aglycones by using 2-aminobenzyl alcohols and aldehydes from one-pot reaction in a chloroacetic acid catalytic system via aerobic oxidative synthesis. Among the synthesized benzoxazines, 4-(7-chloro-2,4-dihydro-1H- benzod1,3oxazin-2-yl)phenol (compound 7) exhibit significant inhibition towards glucosidase compared to acarbose, with a IC50 value of 11.5 μM. Based upon results generated by in silico target prediction algorithms (Naïve Bayesian classifier), these aglycones potentially target the additional sodium/glucose cotransporter 1 (where a log likelihood score of 2.70 was observed). Furthermore, the in vitro glucosidase activity was correlated with the in silico docking results, with a high docking score for the aglycones towards the substrate binding site of glycosidase. Evidently, the in vitro and in vivo experiments clearly suggest an anti-hyperglycemic effect via glucose uptake inhibition by 4-(7-chloro-2,4-dihydro-1H-benzod1,3oxazin-2-yl)phenol in the starved rat model. These synthetic aglycones could constitute a novel pharmacological approach for the treatment, or re-enforcement of existing treatments, of type 2 diabetes and associated secondary complications. © 2014 Bharathkumar et al
Detecting Extreme Events in Gridded Climate Data
No full textAbstractDetecting and tracking extreme events in gridded climatological data is a challenging problem on several fronts: algorithms, scalability, and I/O. Successful detection of these events will give climate scientists an alternate view of the behavior of different climatological variables, leading to enhanced scientific understanding of the impacts of events such as heat and cold waves, and on a larger scale, the El Niño Southern Oscillation. Recent advances in computing power and research in data sciences enabled us to look at this problem with a different perspective from what was previously possible. In this paper we present our computationally efficient algorithms for anomalous cluster detection on climate change big data. We provide results on detection and tracking of surface temperature and geopotential height anomalies, a trend analysis, and a study of relationships between the variables. We also identify the limitations of our approaches, future directions for research and alternate approaches
Design, Modeling and Simulation of a Novel Variable Reluctance Type Linear Ferrofluid Pump
No full textIn this paper, a novel design of variable reluctance type linear ferrofluid pump is proposed. The design is based on the concept of axial pressure gradient of ferrofluid in an external magnetic field. The pump is actuated by two phases of switched DC magnetic field. The conceptual design development of the pump is discussed in detail. The proposed design is modeled and simulated in terms of its equivalent electrical circuit. The equivalent electrical parameters are based on hydraulic-electric analogy. Simulation results of flow rate for different actuation frequency, sequencing methods and discharge head are discussed and analyzed
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