Kinetics of Length Scale Dependent Deformation of Gold Microspheres and Micropillars

In this thesis length and time scale dependence of the operative plastic deformation mechanisms in Au is studied. Uniaxial compression tests were performed at various loading rates on FIB-milled Au micropillars and single-crystalline Au microspheres of diameter ranging from 0.8 to 6.0 µm to investigate the incipient and bulk plasticity events. Constant-load ambient-temperature creep tests were performed on the micropillars to study the time-dependent plasticity at very slow strain rates. Uniaxial compression tests were also performed on coated Au microspheres to study the effect of extrinsic constraint on the deformation mechanisms. During uniaxial compression, both the Au micropillars and microspheres displayed strain jumps, the frequency of which decreased with increasing sample diameter and increasing resolved shear stress. The bulk flow stress, corresponding to 5% – 20% average compressive strain, was dependent upon both the strain rate and the specimen diameter. Analysis of the apparent activation volume, V*, and energy, Q*, of the deformation process indicated that the operative deformation mechanism for the small 0.8 µm diameter pillars and spheres was characteristic of a mechanism limited by surface nucleation of dislocations while larger diameter samples displayed values indicative of the more common dislocation-obstacle interaction limited deformation mechanism. The deformation-rate dependence of incipient plastic deformation of the Au micropillars and microspheres was also dependent upon the strain rate and sample diameter. For the smallest, sub-micrometer size, samples the incipient plasticity was controlled by heterogeneous dislocation nucleation events, while a dislocation-obstacle interaction limited glide process was found to be operative in the larger specimens. In the extrinsic constraint study, Au microspheres that were coated with a 40 – 80 nm thick Ni layer displayed a slightly increased flow stress compared to similar size uncoated microspheres. The estimated V* and Q* values for the coated microspheres suggest that the mechanism responsible for the initiation of first dislocation motion is essentially the same regardless of the presence of a constraining coating

Critical Role of Artificially Intelligent Conversational Chatbot

Artificially intelligent chatbot, such as ChatGPT, represents a recent and powerful advancement in the AI domain. Users prefer them for obtaining quick and precise answers, avoiding the usual hassle of clicking through multiple links in traditional searches. ChatGPT's conversational approach makes it comfortable and accessible for finding answers quickly and in an organized manner. However, it is important to note that these chatbots have limitations, especially in terms of providing accurate answers as well as ethical concerns. In this study, we explore various scenarios involving ChatGPT's ethical implications within academic contexts, its limitations, and the potential misuse by specific user groups. To address these challenges, we propose architectural solutions aimed at preventing inappropriate use and promoting responsible AI interactions.Comment: Extended version of Conversation 2023 position pape

Changes in Color and Physiological Components of The Postharvest Mango (Mangifera indica L.) Influenced by Different Levels of GA3

Abstract - This experiment consisted of two popular mango varieties in Bangladesh (viz., Langra and Khirshapat) and four different levels of Gibberellic acid (GA3) solution, namely control, 100, 200 and 400 ppm. The two factors experiment was assigned in randomized complete block design with tree replicates. Data obtained from various biochemical analyses in terms of physicochemical properties and shelf life of postharvest mango, were recorded and statistically analyzed for comparison among the mean values using DMRT and LSD. The results of the experiments exhibited that only the single effect of varieties was found to be significant in most of the parameters studied. Variety the Langra performed better in accumulating higher quantity of dry matter, ash, vitamin c content in all four experiments over Khirshapat. On the other hand, the Khirshapat showed better performance in achieving higher quantity of moisture, progressively lost physiological weight as well as extended shelf life and delayed skin color changes than Langra at all the storage duration. Keywords: Postharvest mango; Gibberellic acid; physiological components

Rise in childhood obesity with persistently high rates of undernutrition among urban school-aged Indo-Asian children

Background: Childhood obesity is an emerging global public health challenge. Evidence for the transition in nutrition in Indo-Asian developing countries is lacking. We conducted these analyses to determine the trends in nutritional status of school-aged children in urban Pakistan. Methods: Data on the nutritional status of children aged 5 to 14 years from two independent population-based representative surveys, the urban component of the National Health Survey of Pakistan (NHSP, 1990 - 1994) and the Karachi survey (2004 - 2005), were analysed. Using normative data from children in the United States as the reference, trends for age- and gender-standardised prevalence (95% CI) of underweight (more than 2 SD below the weight-for-age reference), stunted (more than 2 SD below the height-for-age reference) and overweight and obese (body mass index (BMI) 85(th) percentile or greater) children were compared for the two surveys. The association between physical activity and being overweight or obese was analysed in the Karachi survey using logistical regression analysis. Results: 2074 children were included in the urban NHSP and 1675 in the Karachi survey. The prevalence of underweight children was 29.7% versus 27.3% (p=0.12), stunting was 16.7% versus 14.3% (p=0.05), and prevalence of overweight and obese children was 3.0 versus 5.7 (p \u3c 0.001) in the NHSP and Karachi surveys, respectively. Physical activity was inversely correlated with being overweight or obese (odds ratio, 95% CI, 0.51, 0.32 - 0.80 for those who engaged in more than 30 minutes of physical activity versus those engaged in less than 30 minutes\u27 activity). Conclusions: Our study highlights the challenge faced by Pakistani school-aged children. There has been a rapid rise in the number of overweight and obsese children despite a persistently high burden of undernutrition. Focus on prevention of obesity in children must include strategies for promoting physical activity