903 research outputs found
Chalcogenide Sensitized Carbon Based TiO2 Nanomaterial For Solar Driven Applications
No full textThe demand for renewable energy is growing because fossils fuels are depleting at a rapid pace. Solar energy an abundant green energy resource. Utilizing this resource in a smart manner can resolve energy-crisis related issues. Sun light can be efficiently harvested using semiconductor based materials by utilizing photo-generated charges for numerous beneficial applications. The main goal of this thesis is to synthesize different nanostructures of TiO2, develop a novel method of coupling and synthesizing chalcogenide nanocrystals with TiO2 and to study the charge transportation effects of the various carbon allotropes in the chalcogenide nanocrystal sensitized TiO2 nanostructure.We have fabricated different nanostructures of TiO2 as solar energy harvesting materials. Effects of the different phases of TiO2 have also been studied. The anatase phase of TiO2 is more photoactive than the rutile phase of TiO2, and the higher dimension of the TiO2 can increase the surface area of the material which can produce higher photocurrent.Since TiO2 only absorbs in the UV range; to increase the absorbance TiO2 should be coupled to visible light absorbing materials. This dissertation presents a simple approach to synthesize and couple chalcogenide nanocrystals with TiO2 nanostructure to form a heterostructured composite. An atmospheric pressure based, single precursor, one-pot approach has been developed and tested to assemble chalcogenide nanocrystal on the TiO2 surface. Surface characterization using microscopy, X-ray diffraction, and elemental analysis indicates the formation of nanocrystals along the nanotube walls and inter-tubular spacing. Optical measurements indicate that the chalcogenide nanocrystals absorb in the visible region and demonstrate an increase in photocurrent in comparison to bare TiO2 nanostructure. The CdS synthesized TiO2 nanostructure produced the highest photocurrent as measured in the three electrodesystem. We have also assembled the PbS nanocrystal sensitized photoanode using the one pot method.Finally, the charge transportation effect of carbon allotropes has been studied. For this we assembled TiO2 conductive carbon chalcogenide nanocomposite system. Surface and elemental characterization using electron microscopy, EDX (energy dispersive x-ray) and x-ray diffraction pattern, provide the insights into the assembly of the nanostructure. Optical absorbance, Photo chronometry, Linear sweep voltammetry, and electrochemical impedance analysis have been used to provide opto-electronic performance of the material. We have studied the loading effect of various carbon allotropes, [fullerene (C60), reduced graphene oxide (RGO), carbon nanotubes (CNTs), and graphene quantum dots (GQDs)], loading effect of chalcogenide, and effect of nitrogen doping on the carbon allotropes to optimize the performance of the heterostructure.This dissertation is expected to impact the materials synthesis strategies and assemble the nanostructures used in composite electrode driven applications in the area of photo electrochemistry, PV, solar-fuels, and other associated topics of energy storage and sensing
Tailored SID & Profile Allocation for Amsterdam Airport Schiphol
No full textCurrently, only one Standard Instrument Departure (SID) track and one flight procedure is used per runway departure fix combination. In contrast to tailored arrivals, the potential benefit of tailored departures has been left relatively undiscovered. The research objective is to quantify the potential benefit of tailored SID-s and profile allocation for Amsterdam Airport Schiphol by developing a model that is capable of simulating departure trajectories per runway departure fix and optimize the overall allocation of departing aircraft for noise and fuel consumption. The proposed methodology includes a two-step modelling framework. The two models involve the design of novel tailored departure trajectories using a multi objective genetic algorithm and the computation of optimal flight allocation by means of Mixed Integer Linear Programming (MILP). A case study is presented and serves as proof of concept.Aerospace EngineeringAerospace Transport & Operation
Micromechanical investigations of the remarkable damage tolerance in tooth-enamel of Hadrosaurid dinosaurs
No full textOverview: The principal objective of this research is to understand the biomechanical form, function, and structure of the enamel (a ceramic-like composite) known as aprismatic coarse wavy enamel (CWE) in the grinding dentition of large herbivores hadrosaurid dinosaurs. Our preliminary analysis of this tissue shows an undulating wavy structure in WE composed of folded layers of hydroxyapatite crystallites separated by thin layers of loosely aggregated interlayer matrix. This study specifically focuses on how the undulating wavy structure of this enamel helped dinosaurs’ teeth to deflect cracks and provided the exceptional strength and toughness to mitigate the effects of fracture promoting sediments while masticating.
A set of experimental tasks involving microstructure characterization and small-scale mechanical testing techniques were proposed to achieve the following principal objectives: For microstructural characterization we used optical microscopy (surface topography), scanning electron microscopy (SEM) (surface morphology), Raman spectroscopy (molecular fingerprint) and atom probe tomography (atomic scale composition). This was correlated with the small-scale testing techniques like spherical nanoindentation (sub µm to 10s of µm volume- achieved by changing indenter radius) and more specialized in-situ micropillar compression testing (few µm to 10s of µm volume – achieved by changing pillar dimensions). These tests were performed for: a) Individual layers probing local response and b) for bulk CWE probing global response. The structure property relationship showed the most prominent effect of elastic mismatch present among the individual layers and the undulating wavy interfaces in influencing the damage tolerance behavior of CWE. Furthermore, the findings of this study were employed to develop a bio inspired damage tolerant metal-ceramic metal ceramic nanocomposite laminate with elastic mismatch and a degree of undulating interfaces present among the alternating metal ceramic layers. The fracture experiments revealed similar crack deflection behavior as seen in CWE. The knowledge gained from this thesis research will be advantageous in 1) Applied materials sciences: the field of multilayer composites where alternating layers of stiff vs. compliant material along with the introduction of waviness among the layers (similar to WE structure) has showed improved crack deflection abilities and 2) Evolutionary biology and paleontology, where understanding gained from this research can be applied to more complex grinding dentition like modified radial enamel (MRE) found in the grinding dentition of horses, bovids, suids etc., and irregular enamel found in mammoths and elephant
Micromechanical investigations of the remarkable damage tolerance in tooth-enamel of Hadrosaurid dinosaurs
No full textOverview: The principal objective of this research is to understand the biomechanical form, function, and structure of the enamel (a ceramic-like composite) known as aprismatic coarse wavy enamel (CWE) in the grinding dentition of large herbivores hadrosaurid dinosaurs. Our preliminary analysis of this tissue shows an undulating wavy structure in WE composed of folded layers of hydroxyapatite crystallites separated by thin layers of loosely aggregated interlayer matrix. This study specifically focuses on how the undulating wavy structure of this enamel helped dinosaurs’ teeth to deflect cracks and provided the exceptional strength and toughness to mitigate the effects of fracture promoting sediments while masticating.
A set of experimental tasks involving microstructure characterization and small-scale mechanical testing techniques were proposed to achieve the following principal objectives: For microstructural characterization we used optical microscopy (surface topography), scanning electron microscopy (SEM) (surface morphology), Raman spectroscopy (molecular fingerprint) and atom probe tomography (atomic scale composition). This was correlated with the small-scale testing techniques like spherical nanoindentation (sub µm to 10s of µm volume- achieved by changing indenter radius) and more specialized in-situ micropillar compression testing (few µm to 10s of µm volume – achieved by changing pillar dimensions). These tests were performed for: a) Individual layers probing local response and b) for bulk CWE probing global response. The structure property relationship showed the most prominent effect of elastic mismatch present among the individual layers and the undulating wavy interfaces in influencing the damage tolerance behavior of CWE. Furthermore, the findings of this study were employed to develop a bio inspired damage tolerant metal-ceramic metal ceramic nanocomposite laminate with elastic mismatch and a degree of undulating interfaces present among the alternating metal ceramic layers. The fracture experiments revealed similar crack deflection behavior as seen in CWE. The knowledge gained from this thesis research will be advantageous in 1) Applied materials sciences: the field of multilayer composites where alternating layers of stiff vs. compliant material along with the introduction of waviness among the layers (similar to WE structure) has showed improved crack deflection abilities and 2) Evolutionary biology and paleontology, where understanding gained from this research can be applied to more complex grinding dentition like modified radial enamel (MRE) found in the grinding dentition of horses, bovids, suids etc., and irregular enamel found in mammoths and elephant
NEW SPECTRA OF AND
No full text. David M. Hirst, Chem. Phys. Lett., 128, 504 (1986).Author Institution: Department of Physics, University of New BrunswickExtensive series of new emission bands of and spectrum have been observed in the region 170 nm -- 200 nm from a high frequency discharge through a mixture of a trace of in helium and hydrogen. This spectrum has been recorded at high resolution by a 6.6 m vacuum spectrograph. Rotational and vibrational analyses are carried out and molecular constants of the electronic states are determined. The rotational structure follows a simple transition. Ten bands of and fifteen bands of are explained as transitions between three new excited electronic levels and the lowest state predicted from theoretical The carrier of the spectrum is confirmed by the observed isotopic effect
Human Rights and Development
No full textThis paper presents some of the main indices (Freedom House indices of political rights and civil liberties; World Human Rights indices) measuring the level of human rights in the world's countries. By means of principal components analysis, the author obtains six factors out of the original forty items of the World Human Rights. Similarities and differences concerning the values of the various indices in the world's countries are identified and discussed. In order to identify the possible determinants of these similarities and differences, the author analyses the impact of lagged income and educational development on the level of human rights in the world's countries
Atomic Reconstruction of Au Thin Films through Interfacial Strains
No full textInterfaces play a critical thermodynamic role in the existence of multilayer systems. Due to its utility in bridging energetic and compositional differences between distinct species, the formation of interfaces inherently creates internal strain towards bulk atoms due to the reorganization needed to accommodate such interface. We report the effect of scaling interfacial stress due to deposition of different adlayers on a host thin metal film. Intrinsic property differences between host and de-posited metal atoms result in varying degree of composition and energy gradient within the interface. Interfacial stress can increase defects in the host leading to; i) energy dissipation and reorganization to minimize surface energy, ii) increased material strength. We infer that dissipation of interfacial stress induces defect migration, hence bulk and surface atomic reconstruction as captured by the surface roughness and grain size reduction coupled with concomitant increase in material strength.This is a manuscript of the article published as Martin, Andrew, Jiahao Chen, Chuanshen Du, Manish Kumar, Ian D. Tevis, Boyce Chang, Sid Pathak, and Martin M. Thuo. "Atomic Reconstruction of Au Thin Films through Interfacial Strains." Nano Letters 24, no. 6 (2024): 1967-1973. doi: https://doi.org/10.1021/acs.nanolett.3c04412
Social implication design (SID): A design method to exploit the unique value of the artefact to counteract social problems
No full textThe role of design in changing people’s behaviour and causing social implications has been referred to as an inherent aspect of design. In taking responsibility for this influence of design, emphasis is often placed on the prevention of undesired consequences rather than the realization of desired ones. Little research exists on how to exploit this implicit yet inevitable role of design in the social realm. This paper presents the development of a method to help designers in exploiting this influence of design to realize social benefit. We explain how design is part of the ‘choice architecture’ in social dilemmas and discuss methodological steps we derived from this. We show how the integration of these steps in an existing design method has led to the method Social Implication Design (SID). The SID method has been applied in a project to improve the social situation in a deprived neighbourhood. We discuss the process and the outcome of this and illuminate strengths and weaknesses of the method. We conclude by reflecting on this type of design practice in relation to other practices of social design, and discuss the unique contribution of the artefact when it comes down to solving issues of social kind.Industrial DesignIndustrial Design Engineerin
Lamellar Level Correlations Between Mechanical Behavior and Composition in Mouse Bone
No full textWe studied the lamellar level correlations between the local composition and local mechanical properties in the femur of two inbred strains of mice (A/J and C57BL/6J (B6)), with known differences in the average mineralization and long-bone mechanical properties, to gain insights into how their extracellular matrix is mineralized. The local elastic moduli and indentation yield strengths were determined using spherical nanoindentation stress-strain analysis, while Raman spectroscopy was used to determine the local composition around the indents in a total of 11 samples. Our results show a significant difference in the mineral-to-matrix ratio of the two strains of mice, with the A/J mice showing an overall higher mineral-to-matrix ratio and lower carbonate substitution in the mineral. These differences are prominent in the newer bone and become less significant as the bone matures. Additionally, local mineral-to-matrix ratio was found to be a good indicator of the local mechanical properties.This is a manuscript of the article Published as Vachhani, Shraddha J., Surya R. Kalidindi, Thomas Burr, and Siddhartha Pathak. "Lamellar Level Correlations between Mechanical Behavior and Composition in Mouse Bone." JOM 73, no. 10 (2021): 3034-3045. doi: https://doi.org/10.1007/s11837-021-04808-6
Guideline for Survey, Investigation, and Design of Black Spot Location (SID-BSL) and Its Application in Lampung Province, Indonesia
No full textIn connection with the government's obligation to take responsibility for ensuring the safety of traffic and road transport for road users, it is necessary to conduct Surveys, Investigations, and Design of Black Spot Location (SID-BSL) to reduce traffic accident. Hence a guideline in conducting SID-BSL is needed. In this study, the author compiled a simple technique of prioritization for SID-BSL procedure and applies it to a research on National Roads in the Lampung Province. The technique of prioritization is simplified with four phase activities namely Preparation, Initial Analysis, Detail Survey, and Detail Analysis. The analysis technique is based on the ranking of Black Spot Locations using weighted accident number (WAN). Application procedure is applied on 237 events of accident on the National Roads in Lampung Province resulting five selected BSLs to be treated according to the availability of funds
- …
