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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Self-healing properties of mortar with crystalline admixture: experimental investigation and parameter optimization

Liu, B., Liang, Y., Jiang, J., Shi, J., Yalçınkaya, Ç., Ashour, Ashraf 26 July 2024 (has links)
Yes / The inclusion of crystalline admixture (CA) is a highly effective method for enhancing the self-repairing capabilities of mortar. This study examined the complexing abilities of different complexing agents under varying temperatures, pH levels, and ion species in order to select effective complexing agents for diverse environments, as complexing agents play a crucial role in CAs. After determining the type of complexing agent, an orthogonal array design was used to optimize the components of CA, and the strengthening mechanism of CA for mortar was discussed through microstructure analysis. The results showed that the complexation behavior of triethanolamine (TEA) and glycine performed better than sodium citrate (SC) for different pH, temperatures, and ion species. Meanwhile, TEA and glycine showed complementarity at different stages, so TEA and glycine were used as complexing agents in this study. Based on the orthogonal experiment, the optimal contents of Na2SiO3, Na2CO3, TEA, glycine, Ca(COOH)2, and nano-SiO2 in CA were determined to be 1.0%, 1.0%, 0.04%, 1.0%, 0.5%, and 1.0%, respectively. Under the synergistic effect of TEA and glycine, the hydration of aluminate and ferrialuminate was accelerated, and the hydration degree of cement paste was increased. At 28 d, the contents of CaCO3, C-S-H gel, and ettringite of cement paste with CA were higher than these of plain paste, but its Ca(OH)2 content was lower. Although the Ca(OH)2 content in the cement paste with CA was lower, the Ca(OH)2 crystal structure filled in the pores was larger. Therefore, the mortar mixed with CA exhibited higher compressive strength, water impermeability, and self-healing ability. / The full-text of this article will be released for public view at the end of the publisher embargo on 3 May 2025.
202

Investigation Of Ion Transport Mechanism In Succinonitrile Based Plastic Crystalline Electrolytes

Das, Supti 07 1900 (has links) (PDF)
The present thesis deals in detail the influence of solvent dynamics and solvation on ion transport in succinonitrile based plastic crystalline electrolytes. The main objective of correlating plastic solvent characteristics with ion transport was achieved by probing the electrolyte using characterization techniques at various length and time scales. Although majority of the results presented in this thesis focus on a prototype succinonitrile electrolyte (succinonitrile-lithium perchlorate, SN-LiClO4), the conclusions drawn from the results on SN-LiClO4 are quite general and can be extended to various types of salts as well as plastic crystalline matrices. Chapters 2-5 demonstrate in a systematic and detailed manner the beneficial influence of solvent dynamics on ion transport in the solid state. The thesis comprises of six chapters. A brief discussion of the contents and highlights of the individual chapters are described below: Chapter 1 briefly reviews the importance of various types of electrolytes for electrochemical applications. The chapter starts with a discussion on different types of liquid and solid crystalline electrolytes and their drawbacks in electrochemical devices such as lithium-ion batteries. Following the discussion on the two extremes of electrolytes viz. liquid and solid electrolytes, various soft matter electrolytes including polymer and plastic crystalline materials are discussed. Aims of the thesis are specified in chapter 1. Chapter 2 discusses plastic crystalline electrolytes as prospective electrolytes for electrochemical applications. In this chapter, we present a detailed study of correlation of ion transport with solvent structure and dynamics in lithium perchlorate (LiClO4)-succinonitrile (SN), a prototype succinonitrile based plastic crystalline electrolyte. Significant influences of the salt on the crystallographic structure, trans-gauche isomerism and solvation properties of succinonitrile (SN) are observed. Ionic conductivity (ac-impedance spectroscopy) and single crystal X-ray studies (in-situ cryo crystallography) reveal the influence of configurational isomerism and ion solvation on ion transport in LiClO4-SN. We quantify the ion association using theoretical analysis of Fuoss-Onsager formalism for various LiX-SN (typically X = ClO4-, CF3SO3-, TFSI-) electrolytes. Thermal (differential scanning caloriemetry) and spectroscopic (Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR)) studies have also been discussed in the chapter to support our proposition. Chapter 3 describes our investigation on issues other than salt that are likely to affect ion transport in Li-salt-SN based plastic crystalline electrolytes such as water in sample and sample thermal history. We investigate here in a detailed manner the influence of water and thermal history on SN configurational isomerism and solvation in LiClO4-SN. LiClO4 in SN electrolyte samples were prepared in various ways for the fulfillment of the objectives of the study of the present chapter. Correlation of water and thermal history on ion transport were studied via ac-impedance spectroscopy and room temperature Fourier transform infrared (FTIR) spectroscopy. The ionic conductivity and infra-red findings were supplemented via differential scanning calorimetry (DSC). Chapter 4 presents dielectric relaxation spectroscopy (DRS) to study the various relaxation processes of the plastic crystalline solvent and ionic species responsible for ion-transport in succinonitrile-based electrolytes. For the DRS study, we select the same system i.e. SN-LiClO4 for which the role of solvent dynamics and ion-association on ion transport was discussed in detail in chapter 2. We supplement the ionic conductivity and various spectroscopic investigations highlighted in chapter 2 via study of the frequency dependence of dielectric function. The permittivity data are further analyzed using Havriliak-Negami (HN) and Kohlrausch-Williams-Watta (KWW) functions for identification of various processes and also for detailed insight on the ion transport mechanism. Chapter 5 comprises of the temperature dependence the bulk acoustic phonons in SN and SN-LiX (X = ClO4-, CF3SO3-, TFSI-, Cl-) electrolytes from (200-300) K. Room temperature Brillouin spectra of SN based plastic crystalline electrolytes with different cationic salts (MClO4-, M = Li+, Na+, Rb+) were also measured. The influences of salt concentration and temperature on solvent dynamics and ion-association effect have been investigated in detail for the SN-LiClO4 electrolyte. The Brillouin data were further analyzed using Lorentzian and Fano resonance function for identification of behavior of various Brillouin modes. An attempt was made to understand ion transport mechanism in SN-LiX plastic crystalline electrolytes based on the concept of molecular liquids as opposed to conventional solid state defect chemistry. The chapter also discusses preliminary results on the relaxational dynamics of SN and SN-LiClO4 in the plastic phase examined using quasi elastic neutron scattering (QENS) facility at ILL-Grenoble IN16 beamline. Chapter 6 provides a brief summary of the work presented in the thesis and discusses how knowledge from the present work (chapters 2-5) can be utilized to generate new electrolytes. The system proposed is a liquid electrolyte based on bis-nitrile (G0-CN) which does not possess majority of the detrimental issues associate with conventional liquids and various improvisations of polymer electrolytes. We also show that the various dendrimer generations obtained from the monomer bis-nitrile (G0-CN) can also be utilized as an alternative solvent for generation of liquid electrolytes for electrochemical devices such as (primary/secondary) batteries. In a way, we discuss a novel liquid electrolyte system whose physical (viscosity, dielectric constant) and solvation properties can be tuned easily to fulfill task of specific objectives. The preliminary ionic conductivity, viscosity and electrochemical studies of the Gn-CN-Li-salt (n=0-2) liquid electrolytes show considerable promise. Though the prospective dendrimer solvent is a liquid, we envisage that in future compounds with similar chemical properties can also be synthesized in the soft matter state.
203

Investigation of the effects of ceramide-C16 and n-decane on the polymorphism of phosphatidylethanolamine : a 2H and 31P solid-state NMR and differential scanning calorimetry study

Doroudgar, Mahmoudreza 12 1900 (has links)
No description available.
204

Characterization of Pharmaceutical Materials by Thermal and Analytical Methods

Maheswaram, Manik Pavan Kumar January 2012 (has links)
No description available.
205

Synthesis, Characterization, and Rheology of Functional and Heterocyclic Liquid Crystalline Polymers

Huang, Wenyi January 2006 (has links)
No description available.
206

Stimuli-responsive Materials From Thiol-based Networks

Brenn, William Alexander 01 June 2017 (has links)
No description available.
207

Evaluation of compensatory gain, standardized ileal digestible lysine requirement, and replacing specialty protein sources with crystalline amino acids on growth performance of nursery pigs.

Nemechek, Jeremiah Eugene January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / Michael D. Tokach / A total of 5,212 nursery pigs were used in 11 experiments to evaluate amino acids in nursery pig diets. Experiments 1 and 2 were conducted to determine whether the Lys level fed during one phase of the nursery influenced the response to Lys during subsequent phases. Experiment 1 tested a wide range of dietary Lys in 2 phases and reported that pigs fed high Lys during each period had increased growth performance; however, compensatory growth occurred for the pigs previously fed low Lys diets, resulting in no impact on overall ADG or final BW. Experiment 2 tested a narrow range of dietary Lys in 3 phases and found that marginally deficient diets can be fed in the early nursery phases without influencing final BW or the response to Lys levels in subsequent phases. Both experiments demonstrate that the low dietary Lys levels used in each can be fed in the early nursery phases with no negative impact on overall nursery growth rate provided that adequate levels are fed thereafter. Experiments 3 to 6 were conducted to determine the standardized ileal digestible (SID) Lys requirement of nursery pigs from 7- to 14-kg. Data from all experiments were combined and break-point and quadratic broken-line analysis was used to determine the estimated SID Lys requirement. The SID Lys requirement for optimal growth was at least 1.30% for ADG and 1.37% for G:F, or at least 3.86 and 4.19 g SID Lys/Mcal ME, respectively. Experiments 7 to 11 were conducted to evaluate the effect of replacing specialty protein sources with crystalline AA and AA requirements for 7- to 12-kg pigs. Experiment 7 demonstrated that crystalline AA can be used to replace fish meal in diets with no negative effects on growth performance. Experiment 8 demonstrated that L-Trp, L-Val, and a source of non-essential AA were needed in low-CP, AA-fortified nursery diets to achieve maximum growth performance, whereas the addition of L-Ile was not required. Experiment 9 indicated that feeding greater than 7.35% total Lys:CP decreased growth performance and Exp. 10 indicated that a SID Val:Lys ratio of 65% was sufficient for optimal growth of early nursery pigs. Implementing the results from the previous experiments, Exp. 11 determined that crystalline AA in nursery pigs diets can replace high amounts of fish meal, meat and bone meal, and poultry meal when balanced for minimum AA ratios and maximum Lys:CP with no negative effect on growth performance.
208

Petrography and structure of the Leatherwood Quartz Diorite, Santa Catalina Mountains, Pima County, Arizona

Hanson, Hiram Stanley, 1923- January 1966 (has links)
No description available.
209

Comparison of the performance of silicon and thin film solar cells at the laboratory of the University of Gävle

Baena Juan, Cristian January 2016 (has links)
The huge environmental awareness emerging last years by reason of global warming and greenhouse effect, on one hand, and the need of finding other sources of energy production and conversion due to the declining of fossil resources and the increasing cost of this kind of energy resource, on the other hand, both have led position renewable energies as a powerful alternative on the energy production and conversion. PV-systems have emerged at an exponential rate in recent year as the main candidate and a satisfactory possibility with respect to environmental and economic sustainability. Nowadays, the large volume on photovoltaic market is currently dominated by four types of solar cells, divided by the semiconductor material used to absorb light and convert the energy into electricity: (1) crystalline silicon (monocrystalline and polycrystalline), (2) amorphous silicon, (3) CIGS and (4) cadmium telluride; and among them, monocrystalline silicon and CIGS technologies are installed on the building 45 of the University of Gävle, at the south face of the laboratory. In this context and with the motivation to contribute knowledge on PV field, a comparison between single crystal solar technology and thin film CIGS technology has carried out through f ratio and performance ratio procedures in order to perform an assessment of the energy conversion of each one under field conditions. A logger monitors the power conversion from the PV modules since June 2014 while two pyranometers monitor global and diffuse solar radiation since March 2016. It must take into account that only clear sunny days have been considered during a period from 8:00 to 14:00 in order to avoid shadows effect on the PV systems. The results come to conclude that single crystal silicon modules present a better behavior with respect to energy conversion under no shadows effect conditions by two reason: (1) f ratio, relationship of PV conversion per kW (PV yield) between CIGS and single crystal silicon, is about 87.25% with some variations along a day due to ambient temperature, cell temperature and incidence angle; (2) PV module's performance ratio of monocrystalline silicon modules is higher than thin film CIGS ones during a sunny day about 87.56% and 76.38%, respectively; and they are consistent with usual performance ratio values between 80% and 90% since 2010 onwards. In light of the outcome and in order to confirm these conclusions, it intends to launch a project with the objective of evaluating the data collected and compare the performance of the module after a year of measurements outdoors by the PV module's performance ratio procedure. Along the same lines, the next step of the University of Gävle will be to launch a project with the objective of evaluating the potential to be self-sufficient.
210

Quartz in Swedish iron foundries : exposure and cancer risk

Andersson, Lena January 2012 (has links)
The aims of the studies underlying this thesis were to assess the exposure to quartz in Swedish iron foundries and to determine the cancer morbidity for Swedish foundry workers. A cohort of 3,045 foundry workers and a final measurement database of 2,333 number of samples was established. The exposure measurements showed high levels of respirable quartz, in particular for fettlers and furnace and ladle repair workers with individual 8 hr TWA (GM=0.041 and 0.052 mg/m3; range 0.004-2.1 and 0.0098-0.83 mg/m3). In our database, the quartz concentrations as 8hr TWAs of current and historical data varied between 0.0018 and 4.9 mg/m3, averaging 0.083 mg/m3, with the highest exposures for fettlers (0.087 mg/m3) and furnace and ladle repair workers (0.42 mg/m3). The exposure for workers using respirators assuming full effect when used were assessed quantitatively, revealing workers with actual exposure exceeding the occupational exposure limits. Overall cancer morbidity was not increased, but the incidence of lung cancer was significantly elevated (SIR 1.61; 95 % CI 1.20-2.12). In the cohort study, significant associations between lung cancer and cumulative quartz exposure were detected for quartz doses of 1-2 mg/m3 * year (SIR 2.88; 95 % CI 1.44-5.16) and >2 mg/m3 * year (SIR 1.68; 95 % CI 1.07- 2.52). These findings were not confirmed in the case-control analysis. The agreement between the estimated exposure in our early historical model and the development model showed a regression coefficient of 2.42, implying an underestimation of the historical exposure when using the development model data. The corresponding comparison between the development and the validation model based on our survey data showed a B of 0.31, implying an overestimation of present exposures when using data from the validation model. The main conclusions of the thesis are that certain foundry workers are still exposed to high levels of quartz, and the overall excess lung cancer could not be confirmed in the exposure-response analysis.

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