340 research outputs found
Antecedents, Wide-Spread Consequences, and Strategic Implications of Organizational Corruption
Antecedents, Wide-spread Consequences, and Strategic Implications of Organizational Corruptio
Cytotoxic compounds from the genus Centaurea.
This thesis, which is divided into four chapters, represents an account on the isolation, identification and the assessment of bioactivity of cytotoxic compounds from the genus Centaurea (Family: Asteraceae alto Compositae), a large genus of about 500 species. The first three chapters deal with an introduction of natural products and Centaurea species, followed by the isolation and characterisation of compounds from twelve Centaurea species. The last chapter describes the bioactivities of extracts and isolated compounds from these species. A total of 45 compounds were isolated from twelve Centaurea species, and only C. americana, C. cyanus, C. dealbata and C. macrocephala had previously been studied. Four of these are novel compounds. Four lignans arctiin, matairesinoside, matairesinol and lappaol A were isolated fromthe methanol extract of C. macrocephala seeds. Arctiin and matairesinoside were also isolated from the methanol extract of C. americana, C. bornmuel/eri, C. dealbata, C. huber-morathii, C. mucronifera, C. pamphylica, C. schischkinii and C. urvillei. The methanol extract of C. americana also afforded 20-hydroxyecdysone, 24-hydroxyecdysone, lappaol A, arctigenin and a novel compound, 3"-O-caffeoyl(9"'->3")-arctiin. The methanol extract of C. cyanus produced lariciresinol 4-0-B-D-glucoside, berchemol, moschamine and cis-moschamine. Arctigenin, astragalin, afzelin, matairesinol and a novel indole alkaloids, schischkiniin, were isolated from the methanol extract of C. schischkinii. Extract from C. bornmuelleri afforded arctigenin, astragalin, afzelin and matairesinol. The methanol extract of C. mon/ana yielded berchemol, berchemol 4'-O-B-D-glucoside, p-coumaroylquinic acid, cis-pcoumaroylquinic acid, pinoresinol, pinoresinol mono methyl ether, pinoresinol dimethyl ether, pinoresinol 4-0-B-D-glucoside, pinoresinol 4,4'di-0-B-D-glucoside, pinoresinol 4-0-apiose-(1->2)-B-D-glucoside, centcyamine, cis-centcyamine, N-(4-hydroxycinnamoyl)-5-hydroxytryptamine, cis-N-(4-hydroxycinnamoyl)-5-hydroxytryptamine, moschamine, cis-moschamine, tryptamine and two novel compounds, flavanone-apiose-glucuronic acid and montamine. C. gigantea afforded arctiopicrin, 8-0-(4-hydroxy-3-methylbutanoyl)-salonitenolide, chlorogenic acid, cirsiliol, isoquercetrin, orientin, isoorientin and 4"-hydroxybenzoyl-isoorientin. General toxicity, cytotoxicity and antioxidant activity of the extracts and isolated compounds were evaluated, respectively, by the brine shrimp lethality assay, MTT assay on human colon cancer cell line (CaCo-2) and DPPH assay. Among all the species, the methanol extract of C. bornmuelleri, C. gigantea, C. huber-morathii and C. montana were the most toxic extracts in brine shrimp lethality and MTT assay. Arctigenin (IC50=7.0 mM), matairesinol, montamine (IC50=43.9 mM) and lappol A, schischkiniin, arctiopicrin (IC50=8.5 mM) and 8-0-(4-hydroxy-3-methylbutanoyl)-salonitenolide (IC50=26.4 mM) showed higher cytotoxicity against MTT assay. Matairesinoside (IC50=2.2 x 10-3 mg/mL), matairesinol (IC50=2.0 x 10-3 mg/mL) and schischkiniin (lC50=3.8 x 10-3 mg/mL) exhibited significant free radical scavenging activities towards DPPH assay
Effect of thermal annealing and carbon implantation on the functional properties of nanocomposite TiSiN coatings on steel
This PhD research contributes to the part of advanced materials technology. The machining industry currently faces tremendous pressures with the need for durable cutting tools suitable for eco-friendly high speed machining operations becoming acute. In this thesis innovative design and synthesis strategies are explored to tailor the properties of nanocomposite coatings. Advanced characterisation techniques are applied to identify the mechanisms that control the mechanical, tribological, and corrosion behaviours of these coatings. Cutting tools protected by these coatings are anticipated to exhibit a unique combination of superior toughness and greater resistance to wear and corrosion, providing significant economic and environmental benefits. The thin ceramic coatings are commonly applied to various kinds of steel cutting and machining tools to enhance their mechanical and tribological properties. The most common ceramic coating is TiN. But the major issues that hamper the application of TiN are high friction co-efficient (typically~0.5), lower hardness, lower thermal stability (~5000 C) and lower corrosion resistance. To address some of these problems, TiSiN nanocomposite coatings are developed, which have super-hardness, better thermal stability (~10000C) and better corrosion resistance. But the as-deposited TiSiN coating still has high co-efficient of friction (~0.4) and high residual stress (~7-9 GPa) which consequently affect the adhesion and toughness of the coating. This project aims to address these problems by (a) the application of carbon implantation to modify the structure and chemistry of the surface layer of the nanocomposite coatings with reduced friction and residual stress; and (b) thermal annealing of the nanocomposite coating to reduce the residual stress with enhanced fracture toughness, better corrosion resistance and more thermal stability. In addition, the role of microstructure, residual stress and defects of these hard coating in corrosive environment will be studied. For this research, a combination of microstructural and mechanical properties characterization, corrosion analysis, tribological test and finite element modelling facilities will be used. The study includes focused ion beam (FIB) milling and transmission electron microscopy (TEM), Synchrotron X-Ray Diffraction (XRD), X-ray Photo Spectroscopy (XPS), Energy dispersive X-Ray (EDX), nanoindentation, nano-scratching, potentio-dynamic polarization cell and Atomic force microscopy(AFM)
Network tomography application in mobile ad-hoc networks.
The memorability of mobile ad-hoc network (MANET) is the precondition of its management, performance optimization and network resources re-allocations. The traditional network interior measurement technique performs measurement on the nodes or links directly, and obtains the node or link performance through analyzing the measurement sample, which usually is used in the wired networks measurement based on the solid infrastructure. However, MANET is an infrastructure-free, multihop, and self-organized temporary network, comprised of a group of mobile nodes with wireless communication devices. Not only does its topology structure vary with time, but also the communication protocol used in its network layer or data link layer is diverse and non-standard. Specially, with the limitation of node energy and wireless bandwidth, the traditional interior network measurement technique is not suited for the measurement requirement of MANET. In order to solve the problem of interior links performance (such as packet loss rate and delay) measurement in MANET, this dissertation has adopted an external measurement based on network tomography (NT). Being a new measurement technology, NT collects the sample of path performance based on end-to-end measurement to infer the probability distribution of the network logical links performance parameters by using mathematical statistics theory, which neither need any cooperation from internal network, nor dependence from communication protocols, and has the merit of being deployed exibly. Thus from our literature review it can be concluded that Network Tomography technique is adaptable for ad-hoc network measurement. We have the following contribution in the eld of ad-hoc network performance: PLE Algorithm: We developed the PLE algorithm based on EM model, which statistically infer the link performance. Stitching Algorithm: Stitching algorithm is based on the isomorphic properties of a directed graph. The proposed algorithm concatenates the links, which are common over various steady state period and carry forward the ones, which are not. Hence in the process it gives the network performance analysis of the entire network over the observation period. EM routing: EM routing is based on the statistical inference calculated by our PLE algorithm. EM routing provides multiple performance metric such as link delay and hops of all the possible path in various time period in a wireless mesh network
Description of Digestive Tract of Notonecta Glauca Linn., the Indian Backswimmer
The backswimmer, Notonecta glauca Linnaeus for the morphological and bioecological investigations were collected during, the months of July to November from various ponds, ditches, and canals of Mathura and its nearby areas. These bugs were easily recognised due to their oblong, convex body; large eye; short four jointed antennae; four joined rostrum; large triangular scutellum; anterior legs inserted at the posterior margin of the pronotum; moderate long pronotum; last joint of antennae being must shorter than the penultimate one and posterior tarsi being without unguiculi. These insects are commonly known as water boatman and backswimmer as they swim on their backs with the help of their long oar-like hind legs. They are extremely predaceous and are very common around the edges of freshwater reservoirs such as ponds, lakes, and streams throughout India and the way be easily taken with a net. In the present study, a detailed description of the digestive tract of the aforesaid insect has been noted
Explainable Lung Disease Classification from Chest X-Ray Images Utilizing Deep Learning and XAI
Lung diseases remain a critical global health concern, and it's crucial to
have accurate and quick ways to diagnose them. This work focuses on classifying
different lung diseases into five groups: viral pneumonia, bacterial pneumonia,
COVID, tuberculosis, and normal lungs. Employing advanced deep learning
techniques, we explore a diverse range of models including CNN, hybrid models,
ensembles, transformers, and Big Transfer. The research encompasses
comprehensive methodologies such as hyperparameter tuning, stratified k-fold
cross-validation, and transfer learning with fine-tuning.Remarkably, our
findings reveal that the Xception model, fine-tuned through 5-fold
cross-validation, achieves the highest accuracy of 96.21\%. This success shows
that our methods work well in accurately identifying different lung diseases.
The exploration of explainable artificial intelligence (XAI) methodologies
further enhances our understanding of the decision-making processes employed by
these models, contributing to increased trust in their clinical applications
Performance evaluation of a PMDC motor with battery storage control and MPPT based solar photovoltaic system
This paper analyzes and demonstrates the performance of a solar photovoltaic (SPV)-fed permanent magnet DC (PMDC) motor under various operating conditions. In this configuration, a 5HP PMDC is coupled to a SPV system and a boost converter has been interfaced between them to regulate the DC output voltage acquired from the SPV system. The switching pulse to the converter has been provided by the maximum power point tracking (MPPT) controller (P&O and INC) in order to acquire maximum and desired power across the DC link with varying irradiance. A battery energy storage system (BESS) is often used in association with this configuration caused by the non-linear nature of the SPV system and to overcome the volatility of the DC connection affected by environmental effects. For this purpose, a double loop PI controller is analyzed, and examined the DC link. Additionally, the operation of bidirectional DC-DC converter in buck and boost mode during battery charging and discharging is also performed. This operation ensures maintaining a constant and continuous power across the DC link to regulate the PMDC motor consistently. A comparison of results has also been presented for both incremental and conductance (INC) and P&O controllers. The mathematical modeling of configuration has been performed in MATLAB/Simulink software. The results and key findings have been tabulated and even elaborated graphically
Derivati feniloctene kiseline s antioksidativnim učinkom iz sjemenki biljke Ilex aquifolium
Reversed-phase preparative HPLC analysis of the methanol extract of the seeds of Ilex aquifolium afforded two antioxidant phenylacetic acid derivatives, 2,4-dihydroxyphenylacetic acid (1) and 2,4-dihydroxyphenylacetic acid methyl ester (2). The structures were determined by spectroscopic methods. In the DPPH assay for antioxidant activity, the IC50 values of 1 and 2 were 1.50 x 10-3 and 2.55 x 10-3 mg mL-1, respectively, compared to 2.88 x 10-5 mg mL-1 of quercetin, a natural antioxidant.Reverzno-faznom preparativnom HPLC analizom metanolnog ekstrakta sjemenki biljke Ilex aquifolium izolirana su dva derivata feniloctene kiseline s antioksidativnim učinkom, 2,4-dihidroksifeniloctena kisleina (1) i metilni ester 2,4-dihidroksifeniloctene kiseline (2). Njihove strukture određene su spektroskopskim metodama. U DPPH testu na antioksidativno djelovanje, IC50 vrijednosti spojeva 1 i 2 bile su 1.50 x 10-3 i 2.55 x 10-3 mg mL-1, dok je IC50 prirodnog antioksidansa kvercitina bila 2.88 x 10-5 mg mL-1
Awareness and likelihood of accepting COVID-19 vaccines among the university students of Bangladesh
Massive vaccination is very important to end the coronavirus disease 2019 (COVID-19) pandemic. This study determined the willingness to receive a COVID-19 vaccine by the university students of Bangladesh and identified their apprehension about the effectiveness and safety of COVID-19 vaccines. Students were invited to complete an online cross-sectional survey (April 3 to June 10, 2021) to explore the intention to receive a COVID-19 vaccine and other factors regarding the responsiveness of the COVID-19 vaccine. Among the 191 respondent students, 52.9% willingly agreed to receive a vaccine, where the remaining was either not decided yet (27.7%) or was not intended to get vaccinated (15.7%). The odd of getting a vaccine were only 1.15. About 83.2% of students were conscious about the severity of COVID-19 and many students responded that they are well-versed about vaccine activity (67.5%) and risk factors (66%). Among the approved vaccines, most students preferred the Oxford-AstraZeneca COVID-19 vaccine ChAdOx1 (38.7%) and Pfizer-BioNTech COVID-19 vaccine BNT162b2 (34%). As some of the students still have lesser intent to accept vaccines, public health officials need to be more proactive to focus on vaccine safety and benefits to enhance vaccine coverage among university students of Bangladesh
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