ORCID Profile
0000-0002-7449-1151
Current Organisations
The University of Texas at Austin
,
University of Engineering and Technology
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Publisher: MDPI AG
Date: 12-08-2022
DOI: 10.3390/SU14169989
Abstract: This study investigates the influences of three types of locally available low-cost Fiber Reinforced Polymers (FRP) wraps and two concrete mix designs on the axial behavior of FRP confined concrete. The experimental program comprised four unconfined (control), four glass FRP Matt Strand (GFRP-MS) confined concrete, four glass FRP Rowing (GFRP-R) confined concrete and four carbon FRP (CFRP) confined concrete specimens with a diameter of 150 mm and a height of 300 mm tested under axial compression. The specimens were prepared using two normal strength concrete mix designs, i.e., Mix-A and Mix-B. The experimental results exhibited that an increase in the confined concrete strength per unit cost ratio of a single layer of GFRP-MS was about two times of a single layer of CFRP wrap, whereas the increase in confined concrete strength per unit cost ratio of single layer of GFRP-R was about four times of a single layer of CFRP wrap. GFRP-MS and GFRP-R wraps can exhibit similar confined strengths as CFRP wrap with six and twelve times lower costs, respectively, than CFRP wrap. Mix-B concrete specimens exhibited higher confined concrete strengths but lower confined concrete strain than Mix-A concrete specimens. A database of 140 FRP confined concrete specimens was developed based on a set of specific criteria to develop a design-oriented model to predict the FRP confined concrete strength. The predicted confined concrete strengths matched well with the experimental confined concrete strengths. The two layers of GFRP-R exhibited similar confined concrete strength as CFRP wrap. In addition, GFRP-R exhibited high cement strength index (CSI) and low embodied CO2 index (CI).
Publisher: ASTM International
Date: 02-07-2019
DOI: 10.1520/JTE20180660
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 05-2020
Publisher: Proceedings of the National Academy of Sciences
Date: 19-11-2018
Abstract: The type VI secretion system (T6SS) is a molecular weapon used for interbacterial competition. It acts like a crossbow bolt to deliver toxic effectors into target cells. Here we characterize a T6SS toxin which we call Tse7. We show that it is a DNase and that its two-domain PAAR-nuclease structure allows coupling to the T6SS VgrG tip via the PAAR domain. Disruption of this interface abrogates toxin delivery and results in the loss of interbacterial killing ability. We identify the corresponding immunity protein, Tsi7, and show it directly interacts with the Tse7 toxin. Finally, as Tse7–Tsi7 sequences vary significantly between Pseudomonas aeruginosa strains, and as Tsi7 protection is strain specific, we show that this toxin/immunity pair contributes to self- nonself-recognition.
Publisher: Springer Science and Business Media LLC
Date: 19-08-2021
Publisher: SAGE Publications
Date: 04-12-2018
Abstract: Numerous research studies experimentally investigated the axial compressive behavior of fiber-reinforced polymer tube confined concrete cylinders in the past two decades. However, only a limited number of research studies developed stress–strain models to predict the strength and strain enhancement ratio of fiber-reinforced polymer tube confined concrete cylinders under axial compression. The available strength and strain enhancement ratio models of fiber-reinforced polymer tube confined concrete cylinders are a function of actual confinement ratio only. This study develops strength and strain enhancement ratio models for circular fiber-reinforced polymer tube confined concrete under axial compression based on artificial neural network analyses using Purelin and Tansig transfer functions. The developed strength and strain enhancement ratio models are functions of actual confinement ratio, orientation of fibers, height to diameter ratio, and axial strain in unconfined concrete at peak axial stress. The formulation and performance evaluation of the developed strength and strain enhancement ratio models are carried out using experimental investigation results of 238 circular fiber-reinforced polymer tube confined concrete under concentric axial compression compiled from a database of 599 fiber-reinforced polymer tube confined concrete specimens. The predictions of the developed strength and strain enhancement ratio models match well with the experimental investigation results of the compiled database. The developed strength and strain enhancement ratio models exhibit smaller statistical errors than the available models in the research studies for predicting the strength and strain enhancement ratios of circular fiber-reinforced polymer tube confined concrete under axial compression.
Publisher: American Society of Civil Engineers (ASCE)
Date: 06-2017
Publisher: Microbiology Society
Date: 09-08-2022
DOI: 10.1099/MIC.0.001217
Abstract: The discovery of penicillin by Alexander Fleming marked a new era for modern medicine, allowing not only the treatment of infectious diseases, but also the safe performance of life-saving interventions, like surgery and chemotherapy. Unfortunately, resistance against penicillin, as well as more complex β-lactam antibiotics, has rapidly emerged since the introduction of these drugs in the clinic, and is largely driven by a single type of extra-cytoplasmic proteins, hydrolytic enzymes called β-lactamases. While the structures, biochemistry and epidemiology of these resistance determinants have been extensively characterized, their biogenesis, a complex process including multiple steps and involving several fundamental biochemical pathways, is rarely discussed. In this review, we provide a comprehensive overview of the journey of β-lactamases, from the moment they exit the ribosomal channel until they reach their final cellular destination as folded and active enzymes.
Publisher: Elsevier BV
Date: 2018
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Despoina Mavridou.