944 research outputs found
Experimental Investigations on the Contour Generation of a Reconfigurable Stewart Platform
No full textReconfiguration of Stewart platform for varying tasks accentuates the importance for determination of optimum geometry catering to the specified task. The authors in their earlier work (Satheesh et al., 2008) have indicated the non availability of an efficient holistic methodology for determining the optimum geometry. Further, they have proposed a solution using the variable geometry approach through the formulation of dimensionless parameters in combination with generic parameters like configuration and joint vector. The methodology proposed provides an approach to develop a complete set of design tool for any new reconfigurable Stewart platform for two identified applications viz., contour generation and vibration isolation. This paper details the experimental investigations carried out to validate the analytical results obtained on a developed Stewart platform test rig and error analysis is performed for contour generation. The experimental natural frequency of the developed Stewart platform has also been obtained.</p
Fabrication of a Flexible UV Band-Pass Filter Using Surface Plasmon Metal-Polymer Nanocomposite Films for Promising Laser Applications
No full textWe introduce a strategy for the fabrication of silver/polycarbonate (Ag/PC) nanocomposite flexible films of (20 +/- 0.01) mu m thickness with different filling factor of surface plasmon metal using customized solution cast thermal evaporation method. Structural characterizations confirmed the good crystallinity with cubic phase of Ag nanoparticles in PC films. Moreover, the microstructural evolutions of nanocomposite films are investigated by transmission electron microscopy, which indicates that the metal fraction is in the form of fractals. Additionally, the surface plasmonic behavior of nanocomposite films has been explored in detail to examine the distribution of Ag nanoparticles in PC film by spectroscopic technique. Furthermore, the obtained transmittance spectral features of this nanocomposite film are suitable for the applications of band-pass filter at 320 nm UV range, which is highly desirable for a HeCd laser
Sri Lanka: Kanapathipillai Satheesh Kumar
No full textA document from Amnesty International's Urgent Action Networ
Two-dimensional layered materials-based energy-efficient optoelectronic memories: a leap towards bionic vision
No full textOptoelectronic memories have gained remarkable attention owing to their inherent capability of manipulating charge carriers under the influence of both electrical and light stimuli. The emerging optoelectronic neuromorphic devices can be used in diverse applications, including logical data processing, confidential information recording, and next-generation bionic visual systems. Photosensitive materials are foundational to many technologies, including solar cells, sensors, thin-film transistors, and light-emitting diodes. Recently, two-dimensional (2D) photosensitive materials have found application in bionic visual hardware based on optoelectronic synaptic memristor and memtransistor devices. The synthesis and growth of optoelectronic memories driven by 2D photosensitive materials have opened new horizons in the field of bionic visual systems due to their diverse optical properties, atomic scalability, and ultrafast charge carrier dynamics. This review highlights the recent developments in bionic visual hardware based on optoelectronic synaptic memristive devices and memtransistors, wherein various 2D photosensitive materials and device structures have been utilised. We first summarise the limitations of traditional computing, highlight the key advantages of this novel computing paradigm, and discuss the fundamentals of bio-vision formation. Next, we comprehensively review the various device structures and operating mechanisms of optoelectronic memristive and memtransistor architectures. The recent developments in optoelectronic synaptic devices by incorporating various 2D photosensitive materials and their application in the field of bionic visual perception are also discussed. Finally, we outline the current drawbacks and challenges of optoelectronic neuromorphic devices and the future perspective of bionic visual hardware on real system realisation
Retinomorphic devices beyond silicon for dynamic machine vision
No full textThe human visual system can effectively sense optical information through the retina and process it at the visual cortex. Compared with conventional machine vision, it demonstrates superiority in terms of energy efficiency, adaptability, and accuracy. The retina-inspired machine vision systems can process information near or within the sensors at the front end, thereby compressing the raw sensory data and optimising the input to back-end processor for high-level computing tasks. In recent years, amid surge of interest in artificial intelligence technology, research in retinomorphic devices has achieved breakthroughs in both academic and industrial settings. Herein, we present a comprehensive review of this emerging field -based on several materials classes, such as halide perovskites, two-dimensional materials, organic materials and metal oxides. We discuss the steps taken towards achieving not only static pattern recognition, but also dynamic motion tracking and we identify the key challenges that need to be addressed by the community to push this technology forward
Sri Lanka: ""disappearance"": Kanapathipillai Satheesh Kumar
No full textA document from Amnesty Internationals Urgent Action Networ
Effective multi-biocatalyst system with reusable NADH for transformation of glycerol to value-added dihydroxyacetone
No full textAbstract Glycerol-based biorefinery can be a highly profitable process by producing highly value-added products such as dihydroxyacetone via combined catalytic strategies. Here, two-enzyme system is adopted for the transformation of glycerol into highly valuable dihydroxyacetone as well as cofactor regeneration at the same time. Glycerol dehydrogenase (GDH) and alcohol dehydrogenase (ADH) are co-immobilized within magnetically separable and spherical mesocellular silica foam (Mag-S-MCF), to prepare NER-(GDH/ADH). In details, GDH and ADH are adsorbed into the mesopores of Mag-S-MCF, and further crosslinked within the mesopores of Mag-S-MCF. The resulting nanoscale enzyme reactors (NER) of crosslinked GDH and ADH molecules within the bottle-neck structured mesopores can effectively prevent larger sized crosslinked enzyme aggregates from being leached out of smaller mesopores, due to the bottle-neck mesopore structure of Mag-S-MCF, as well as stabilize the activity of GDH and ADH upon chemical crosslinking, effectively preventing the denaturation of enzyme molecules. More importantly, the proximity of GDH and ADH molecules within mesopores of NER improves the efficiency of cofactor-mediated dual-enzymatic reactions by relieving mass-transfer limitations and improving cofactor recycling in an effective way, expediting both glycerol oxidation and dihydroxyacetone generation at the same time. As a result, the DHA concentration of NER-(GDH/ADH) and the simple mixture of NER-GDH and NER-ADH were 410 μM and 336 μM, respectively. To the best of our knowledge, this report is the first demonstration of stabilized nanoscale multi-enzyme reactor system, equipped with efficient cofactor regeneration within confined mesopores, for efficient glycerol transformation to high-valued dihydroxyacetone. Graphical Abstrac
Characterisation of CRISPR RNA-editing technologies for retinal gene therapy
No full text© 2025 Satheesh KumarEditing of DNA and RNA has been revolutionised by the CRISPR-Cas technology since its first description in 2012. by showcasing versatility as therapeutics, diagnostics and biosecurity tools among others. A broad spectrum of therapeutic gene editing tools have since been developed from the discovery of CRISPR-Cas, including the recently described RNA-targeting Cas13 nucleases. These enzymes enable the targeting of RNA rather than DNA, promising a safer gene editing approach that does not permanently impact the genome. This thesis investigated the potential of novel gene therapies with CRISPR-Cas13 against significant retinal diseases like retinal neovascularisation and inherited retinal degenerations (IRDs).
Firstly, the capacity of a compact CRISPR-Cas13 nuclease (Cas13bt3) to target vascular endothelial growth factor (VEGF) for knockdown was investigated for treatment of neovascular retinal disease, a complication from overexpression of VEGF. Cas13bt3 achieved superior RNA silencing of VEGF RNA compared to previous RNA-targeting methods like RNA interference (RNAi) in mammalian cell lines. When delivered as clinically used viral vectors into 3D retinal organoids, a retinal cell population derived from human stem cells, efficient transduction of retinal pigment epithelial (RPE) cells was observed which corresponded with silencing of VEGF-A RNA. The viruses carrying Cas13bt3 were then delivered into transgenic mice expressing human VEGF where specific silencing of human VEGF and control of the neovascular process was observed, showcasing the safety and efficacy of Cas13bt3 as an anti-VEGF tool.
In a second application, Cas13bt3 was used as an RNA base editor to correct pathogenic IRD mutations. A compact RNA base editor was developed through fusion of inactivated Cas13bt3 with the human ADAR2 (adenosine deaminase acting on RNA 2) enzyme. This Cas13bt3 RNA base editor demonstrated potent activity (>70%) in correcting the specific mutation and recovering protein expression in a reporter assay. To comprehensively study the versatility of Cas13bt3 RNA base editing, all pathogenic G>A nonsense mutations reported in the Leiden Open Variation Database (LOVD) in the human RPE65 gene were targeted. Here, mutations occurred in different contexts for which ADAR2 has varied preferences for editing. Editing rates across the mutations varied, and ADAR2 codon preference did not strictly influence on-target editing, indicating other factors such as target and guide RNA structure play crucial roles. To demonstrate clinical utility of the base editor, USH2A, a gene too large for delivery by effective vectors and causes combined vision and hearing loss, was targeted. Above 50% correction of USH2A mRNA was observed indicating the tool could be used as a clinical tool for currently untreatable IRDs.
Together, these two approaches demonstrated proof-of-concept that AAV delivery of the compact nuclease Cas13bt3 could be used for the treatment of retinal disease. This includes both active Cas13bt3 for RNA knockdown of VEGF in retinal vascular disease, and inactive Cas13bt3-ADAR for precise RNA base editing for currently untreatable IRDs. RNA editing is burgeoning in the gene therapy space and the findings reported in this thesis promise to inform on the future development of RNA-targeted therapeutics for the retina
Performance assessment of vegetable oil based cutting fluids with extreme pressure additive in machining
No full textThe present work focuses on the experimental evaluation of the performance of vegetable
oil based cutting fluids (coconut, canola and sesame oils) with extreme pressure (EP) additive in
machining. Cutting fluids are prepared with three different base oils at three different percentages of
EP additives. Performance of these cutting fluids is assessed by measuring cutting forces, cutting tool
temperature, tool flank wear and surface roughness in turning AISI 1040 steel with coated carbide tool.
Experiments are conducted initially at constant cutting conditions with 5% EP additive in vegetable
oils in order to compare their performance with conventional cutting fluid prepared from soluble oil.
Further evaluation is done by varying percentage of EP additive and cutting conditions as well. The
results indicated that 10% EP additive included in coconut oil based cutting fluid performed better
compared to other vegetable oils and other percentages of EP additive
sj-pdf-1-tam-10.1177_17588359241236442 – Supplemental material for Treatment with nanosomal paclitaxel lipid suspension versus conventional paclitaxel in metastatic breast cancer patients – a multicenter, randomized, comparative, phase II/III clinical study
No full textSupplemental material, sj-pdf-1-tam-10.1177_17588359241236442 for Treatment with nanosomal paclitaxel lipid suspension versus conventional paclitaxel in metastatic breast cancer patients – a multicenter, randomized, comparative, phase II/III clinical study by Chiradoni Thungappa Satheesh, Rakesh Taran, Jitendra Kumar Singh, Shanti Prakash Shrivastav, Nikunj K. Vithalani, Kalyan Kusum Mukherjee, Rajnish Vasant Nagarkar, Tanveer Maksud, Ajay Omprakash Mehta, Krishnan Srinivasan, Mummaneni Vikranth, Satish Ramkrishna Sonawane, Ateeq Ahmad, Saifuddin Sheikh, Shoukath M. Ali, Ronak Patel, Mahesh Paithankar, Lav Patel, Anil Rajani, Deepak Bunger, Alok Chaturvedi and Imran Ahmad in Therapeutic Advances in Medical Oncology</p
- …
