Transfer and Development Length of Prestressing Tendons in Full-Scale AASHTO Prestressed Concrete Girders Using Self-Consolidating Concrete

Self-consolidating concrete (SCC) is a highly workable concrete that flows through densely reinforced or complex structural elements under its own weight. The benefits of using SCC include: a) Reducing labor costs by eliminating the need for mechanical vibration, b) Improving constructability, c) Providing a virtually flawless finish, d) Providing uniform and homogenous concrete, and e) Easily filling a complex shape formwork. Even though SCC is comparable to conventional concrete in terms of strength, the comparability of its bond to steel is less well-defined. This disparity of knowledge becomes more critical when using SCC in prestressed members due to the impact that bond strength has on the transfer and development lengths of prestressing tendons. The increasing interest among Illinois precasters in using SCC in bridge girders has motivated the Illinois Department of Transportation (IDOT) and the Illinois Center for Transportation (ICT) to sponsor this synthesis study, which reviews and combines information from literature discussing the impact of using SCC on the transfer and development lengths of prestressing tendons in AASHTO bridge girders. The primary objectives of this study include: (1) Utilizing the results of previous research to evaluate the effect of using SCC on the transfer and development lengths of prestressing tendons and evaluate how SCC compares with conventional concrete, (2) Investigating the feasibility of using SCC in AASHTO bridge girders without the need for changing current design provisions recommended by the ACI and AASHTO, and (3) Providing IDOT with recommendations regarding the application of SCC in prestressed bridge girders. 17. KeyICT-R27-36published or submitted for publicationis peer reviewe

Vitamin C: A potential regulator of inflammatory response

Introduction: Neutrophils (PMNs) and Macrophages are the first responders recruited consecutively to the site of injury/inflammation. PMNs’ response/fate as well as macrophage reprogramming ultimately determine the course of resolution of inflammation. Physiologic wound healing has a significant inflammatory component. An exaggerated inflammation however is self-defeating leading to delayed healing. Parenteral vitamin C (VitC) attenuated inflammation in murine sepsis models and in patients with sepsis. However information about the mechanisms by which VitC regulates these events is limited. Methods: Humanized mice lacking VitC synthesis capability (Gulo-/-) were used. VitC sufficient and deficient mice were challenged with sterile inflammation, or septic insults. Some VitC deficient mice received parenteral VitC (200mg/kg) following the challenge to give deficient + AscA mice up to 14 days. Using a murine model of excisional wound, two full thickness excisional wounds were created on the back of the different Gulo-/- mice groups. Wound tissues were excised at day 7 and 14 post-wounding for analysis. Cell counts, immunohistochemistry, circulating free DNA, the expression of pro- and anti-inflammatory proteins were investigated. Additional in vitro experiments were carried out using human PMN (huPMNs), THP-1 monocyte/macrophage, and neonatal human dermal fibroblasts (HnDF). Results: VitC deficiency delayed resolution of lung inflammation and led to exaggerated pro-inflammatory responses. PMNs from VitC deficient mice demonstrated increased autophagy, histone citrullination, and NFκB activation, while inhibiting apoptosis. VitC sufficiency/supplementation restored macrophage phenotype, as well as attenuated neutrophil extracellular trap (NET) formation. VitC attenuated pro-inflammatory responses in THP-1 macrophages. In wound healing model, wounds from VitC sufficient/AscA infused mice had lower gene expression of the pro-inflammatory mediators; higher expression of genes promoting wound healing and resolution. Exposure of HnDF to AscA increased their intracellular VitC levels; promoted fibroblast proliferation and induced expression of fibroblast self-renewal genes. Conclusion: Our findings identify VitC as a novel regulator of PMN and macrophage responses. In wound healing, VitC favorably impacted the spatiotemporal expression of transcripts associated with early resolution of inflammation and tissue remodeling. Collectively, these results substantiate the protective notion of parenteral VitC and support its clinical use

Hybrid Silicon Mode-Locked Laser with Improved RF Power by Impedance Matching

The mode-locked laser diode (MLLD) finds a lot of use in applications such as ultra high-speed data processing and sampling, large-capacity optical fiber communications based on optical time-division multiplexing (OTDM) systems. Integrating mode-locked lasers on silicon makes way for highly integrated silicon based photonic communication devices. The mode-locked laser being used in this thesis was built with Hybrid Silicon technology. This technology, developed by UC Santa Barbara in 2006, introduced the idea of wafer bonding a crystalline III- V layer to a Silicon-on-insulator (SOI) substrate, making integrated lasers in silicon chips possible. Furthermore, all mode-locked lasers produce phase noise, which can be a limiting factor in the performance of optical communication systems, specifically at higher bit rates. In this thesis, we design and discuss an impedance matching solution for a hybrid silicon mode-locked laser diode to lower phase noise and reduce the drive power requirements of the device. In order to develop an impedance matching solution, a thorough measurement and analysis of the impedance of the MLLD is necessary and was carried out. Then, a narrowband solution of two 0.1 pF chip capacitors in parallel is considered and examined as an impedance matching network for an operating frequency of 20 GHz. The hybrid silicon laser was packaged together in a module including the impedance- matching circuit for efficient RF injection. In conclusion, a 6 dB reduction of power required to drive the laser diode, as well as approximately a 10 dB phase noise improvement, was measured with the narrow-band solution. Also, looking ahead to possible future work, we discuss a step recovery diode (SRD) driven impulse generator, which wave-shapes the RF drive to achieve efficient injection. This novel technique takes into account the time varying impedance of the absorber as the optical pulse passes through it, to provide optimum pulse shaping

The Blackhole-Dark Matter Halo Connection

We explore the connection between the central supermassive blackholes (SMBH) in galaxies and the dark matter halo through the relation between the masses of the SMBHs and the maximum circular velocities of the host galaxies, as well as the relationship between stellar velocity dispersion of the spheroidal component and the circular velocity. Our assumption here is that the circular velocity is a proxy for the mass of the dark matter halo. We rely on a heterogeneous sample containing galaxies of all types. The only requirement is that the galaxy has a direct measurement of the mass of its SMBH and a direct measurement of its circular velocity and its velocity dispersion. Previous studies have analyzed the connection between the SMBH and dark matter halo through the relationship between the circular velocity and the bulge velocity dispersion, with the assumption that the bulge velocity dispersion stands in for the mass of the SMBH, via the well{}-established SMBH mass{}-bulge velocity dispersion relation. Using intermediate relations may be misleading when one is studying them to decipher the active ingredients of galaxy formation and evolution. We believe that our approach will provide a more direct probe of the SMBH and the dark matter halo connection. We find that the correlation between the mass of supermassive blackholes and the circular velocities of the host galaxies is extremely weak, leading us to state the dark matter halo may not play a major role in regulating the blackhole growth in the present Universe.Comment: Accepted for publication in the Ap

Energy Efficiency Prediction using Artificial Neural Network

Buildings energy consumption is growing gradually and put away around 40% of total energy use. Predicting heating and cooling loads of a building in the initial phase of the design to find out optimal solutions amongst different designs is very important, as ell as in the operating phase after the building has been finished for efficient energy. In this study, an artificial neural network model was designed and developed for predicting heating and cooling loads of a building based on a dataset for building energy performance. The main factors for input variables are: relative compactness, roof area, overall height, surface area, glazing are a, wall area, glazing area distribution of a building, orientation, and the output variables: heating and cooling loads of the building. The dataset used for training are the data published in the literature for various 768 residential buildings. The model was trained and validated, most important factors affecting heating load and cooling load are identified, and the accuracy for the validation was 99.60%