Polymer based microscale and nanoscale technologies for optical and biomedical application

Polymer based micro and nano systems has emerged as a mainstream research in recent times with advent of bio-inspired design of opto-MEMS as wells as bio-MEMS. Polymers have tunable materials characteristics ranging for elastic to brittle nature, optically transparent and biocompatible and biodegradable for application in optics and biomedicine. I tackled four different technological challenges in this research work using novel biomimetic design and biopolymers as listed below. First, I designed wide acceptance angle thin and flat miniaturized solar concentrator by mimicking the wide acceptance angle found in compound eye of insects. I integrated lens, conic spacer and light guide to concentrate and redirect sunlight into small area where PV cell can be installed. My design can have total concentration up to ~40 for acceptance angle of 15ð. Second, I designed and fabricated automated light control switch using IR part of solar spectrum and to change a paraffin micro-chamber volume and actuate the cantilever structure. The cantilever structure when activated frustrates the TIR guided light in the lightguide and control the illumination level. We obtained rms value of illumination change to be 0.012 for input change of 0.018. Third, I developed rapid, inexpensive, reproducible method to make nanoscale patterns in PLLA films using replica-molding techniques. We produce very high fidelity replication of PLLA using double replication from master polycarbonate to PDMS mold and from PDMS mold to PLLA film by drop casting process. The surface characteristics of the nano-patterned film changed drastically form hydrophilic to hydrophobic due to patterning. We also investigate the drug coating process in this film for its use in controlled drug release platform. Finally, I used the drug coated and nano-patterned PLLA film for its potential application in biodegradable coronary stents. We fabricated the stents by rolling the PLLA films into the tube. The controlled drug release was studied by releasing the control and patterned PLLA surface into phosphate buffer saline. We used advanced high performance liquid chromatography coupled with mass spectrometer to measure the amount of drug released as a function of time. The nano-patterned surface has up to 20% slower drug release rate in comparison to the flat surface

Exploring Transfer Learning in Medical Image Segmentation using Vision-Language Models

Medical Image Segmentation is crucial in various clinical applications within the medical domain. While state-of-the-art segmentation models have proven effective, integrating textual guidance to enhance visual features for this task remains an area with limited progress. Existing segmentation models that utilize textual guidance are primarily trained on open-domain images, raising concerns about their direct applicability in the medical domain without manual intervention or fine-tuning. To address these challenges, we propose using multimodal vision-language models for capturing semantic information from image descriptions and images, enabling the segmentation of diverse medical images. This study comprehensively evaluates existing vision language models across multiple datasets to assess their transferability from the open domain to the medical field. Furthermore, we introduce variations of image descriptions for previously unseen images in the dataset, revealing notable variations in model performance based on the generated prompts. Our findings highlight the distribution shift between the open-domain images and the medical domain and show that the segmentation models trained on open-domain images are not directly transferrable to the medical field. But their performance can be increased by finetuning them in the medical datasets. We report the zero-shot and finetuned segmentation performance of 4 Vision Language Models (VLMs) on 11 medical datasets using 9 types of prompts derived from 14 attributes.Comment: 25 pages, 9 figure

Feminization of Agriculture in Nepal and its implications: Addressing Gender in Workload and Decision Making

The study assesses the two approaches of feminization: labor and managerial, and explores the implication of feminization in agricultural production in Gorkha and Chitwan district of Nepal. We examine the degree to which men, women or men and women jointly make agriculture-related decisions, and discuss the labor feminization and managerial feminization using five domains of the Women Empowerment in Agriculture Index (WEAI), relative to the degree to which women’s decision-making power relates to the feminization of agriculture leading to women empowerment and food security. The results revealed that the average workload for women (86.50 hours/week) was more than that for men (55.52 hours/week). Workload was found significantly affected by the total cultivated area (ha), gender of household head, occupation, number of livestock holdings, number of children, number of elders and household location.All aspects of operational and strategic decision making were dominated by jointly made decisions, except in the case of income utilization where female showed dominance. The implication of feminization in agriculture is reflected by reduction in cropping cycle, lower productivity of cereals and vegetables which led to food insecurity by own production. The income from remittance was observed to be mainly used for consumption purposes to ensure food security. It appears that the feminization of agriculture leads to women playing not only important role in decision-making but also more responsibilities and heavier workloads without necessarily resulting in empowerment and improvement in well-being

Precision Nitrogen Management in Spring Rice (Oryza sativa L.) using Decision Support Tools in Chitwan, Nepal

The blanket prescription of nitrogen (N) fertilizer often results in irrational fertilization. To address this issue and align the application of nitrogen fertilizers with the crop-specific demand, it is imperative to save nitrogen resources, maximize the uptake and net income, and subside environmental pollution. In this context, a field experiment was carried out in Kumroj, Chitwan, Nepal during 2022 to assess the growth, yield, and profitability of rice production by comparing different precision nitrogen management practices. The study was carried out in a randomized complete block design with seven treatments and three replications. The treatments included decision support tools for nitrogen management such as the Green Seeker (GS), the Soil plant analysis development Development (SPAD) meter, and the Leaf Color Chart (LCC) combined with basal application of nitrogen at 30 kg ha–1 and the Urea briquette Deep Placement (UDP), the Polymer Coated Urea (PCU), and the Recommended Dose of Fertilizers (RDF, 120 kg N ha–1). The growth, yield, yield attributes, and financial data were taken. Precision nitrogen management techniques significantly enhanced rice growth and yield parameters. GS–guided application required the highest nitrogen demand (155 kg ha–1), while SPAD (80 kg ha–1) and UDP (78 kg ha–1) resulted in lower usage. PCU and UDP enhanced plant height, leaf area index, and above–ground dry matter. Higher grain yield (6.64 t ha–1) was attained with LCC, SPAD (6.44 t ha–1), and UDP (6.41 t ha–1) treatments. GS application exhibited the highest straw yield (11.17 t ha–1), while LCC demonstrated the highest benefit–cost ratio (1.96). This study concluded that SPAD and UDP demonstrated the potential to save nitrogen resources, while LCC and UDP were found profitable

Polymer based microscale and nanoscale technologies for optical and biomedical application

Polymer based micro and nano systems has emerged as a mainstream research in recent times with advent of bio-inspired design of opto-MEMS as wells as bio-MEMS. Polymers have tunable materials characteristics ranging for elastic to brittle nature, optically transparent and biocompatible and biodegradable for application in optics and biomedicine. I tackled four different technological challenges in this research work using novel biomimetic design and biopolymers as listed below. First, I designed wide acceptance angle thin and flat miniaturized solar concentrator by mimicking the wide acceptance angle found in compound eye of insects. I integrated lens, conic spacer and light guide to concentrate and redirect sunlight into small area where PV cell can be installed. My design can have total concentration up to ~40 for acceptance angle of 15à °. Second, I designed and fabricated automated light control switch using IR part of solar spectrum and to change a paraffin micro-chamber volume and actuate the cantilever structure. The cantilever structure when activated frustrates the TIR guided light in the lightguide and control the illumination level. We obtained rms value of illumination change to be 0.012 for input change of 0.018. Third, I developed rapid, inexpensive, reproducible method to make nanoscale patterns in PLLA films using replica-molding techniques. We produce very high fidelity replication of PLLA using double replication from master polycarbonate to PDMS mold and from PDMS mold to PLLA film by drop casting process. The surface characteristics of the nano-patterned film changed drastically form hydrophilic to hydrophobic due to patterning. We also investigate the drug coating process in this film for its use in controlled drug release platform. Finally, I used the drug coated and nano-patterned PLLA film for its potential application in biodegradable coronary stents. We fabricated the stents by rolling the PLLA films into the tube. The controlled drug release was studied by releasing the control and patterned PLLA surface into phosphate buffer saline. We used advanced high performance liquid chromatography coupled with mass spectrometer to measure the amount of drug released as a function of time. The nano-patterned surface has up to 20% slower drug release rate in comparison to the flat surface.</p