Metal building systems are widely used in low-rise (1- or 2-story) building construction for economic reasons. Maximum cost efficiency is usually achieved through optimization of steel weight and the fabrication process by adopting web-tapered members and bolted end-plate connections. However, the cyclic behavior of this kind of system has not been investigated, and no specific seismic design guidelines are available in the United States. Based on both experimental and analytical studies, this dissertation introduces a new design concept utilizing drift evaluation, and proposes a seismic design procedure for metal building systems. Full-scale cyclic testing on a metal building with web-tapered members demonstrated that the system has high deformability, but little ductility. Proper flange bracing was essential to prevent premature lateral-torsional buckling. Test results also showed that the overstrength of this system was very high since the non-seismic load combination governed the design. A correlation study indicated that the failure modes corresponded well with the strength evaluation contained in the AISC LRFD Specification. Numerical simulation using the finite element analysis program ABAQUS demonstrated that good correlations in both the failure mode and the system strength characteristics could be achieved when a proper assumption on the initial geometric imperfections was made. A parametric study showed that the best correlation was found in the models with the first eigen buckling mode shape and an amplitude of Lb/1000 as an initial imperfection (Lb = unbraced length). A drift-based seismic design procedure was then developed. The design goal is to ensure that the elastic drift capacity of the system is larger than the drift demand with a sufficient margin. The drift capacity is calculated using the system overstrength factor, and both drift capacity and demand are estimated utilizing the actual fundamental period. The proposed factor of safety (= 1.4) partially reflects the influence of low damping nature of metal buildings. Case studies using the proposed design procedure indicated that metal frames with heavy walls (i.e., masonry or concrete) based on the current design procedure are very vulnerable to collapse under major earthquake events, but the impact to the design of typical metal buildings without heavy wall attachments is insignificant

Extracellular vesicles (EVs) are the cell-secreted nano- and micro-sized particles consisted of lipid bilayer containing nucleic acids and proteins for diagnosis and therapeutic applications. The inherent complexity of EVs is a source of heterogeneity in various potential applications of the biological nanovesicles including analysis. To diminish heterogeneity, EV should be isolated and separated according to their sizes and cargos. However, current technologies do not meet the requirements. We showed noninvasive and precise separation of EVs based on their sizes without any recognizable damages. We separated atto-liter volumes of biological nanoparticles through operation of the present system showing relatively large volume of sample treatment to milliliters within an hour. We observed distinct size and morphological differences of 30 to 100 nm of exosomes and apoptotic bodies through TEM analysis. Indeed, we confirmed the biological moiety variations through immunoblotting with noninvasively separated EVs opening new windows in study and application of the biological nanoparticles.

Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a significant clinical-therapeutic challenge. Of particular concern is antibiotic treatment failure in infections caused by MRSA that are "susceptible" to antibiotic in vitro. In the current study, we investigate specific purine biosynthetic pathways and stringent response mechanism(s) related to this life-threatening syndrome using genetic matched persistent and resolving MRSA clinical bacteremia isolates (PB and RB, respectively), and isogenic MRSA strain sets. We demonstrate that PB isolates (vs RB isolates) have significantly higher (p)ppGpp production, phenol-soluble-modulin expression, polymorphonuclear leukocyte lysis and survival, fibronectin/endothelial cell (EC) adherence, and EC damage. Importantly, an isogenic strain set, including JE2 parental, relP-mutant and relP-complemented strains, translated the above findings into significant outcome differences in an experimental endocarditis model. These observations indicate a significant regulation of purine biosynthesis on stringent response, and suggest the existence of a previously unknown adaptive genetic mechanism in persistent MRSA infection.

The Southern Ocean surrounding Antarctica is a region that is key to a range of climatic and oceanographic processes with worldwide effects, and is characterised by high biological productivity and biodiversity. Since 2013, the International Bathymetric Chart of the Southern Ocean (IBCSO) has represented the most comprehensive compilation of bathymetry for the Southern Ocean south of 60°S. Recently, the IBCSO Project has combined its efforts with the Nippon Foundation - GEBCO Seabed 2030 Project supporting the goal of mapping the world's oceans by 2030. New datasets initiated a second version of IBCSO (IBCSO v2). This version extends to 50°S (covering approximately 2.4 times the area of seafloor of the previous version) including the gateways of the Antarctic Circumpolar Current and the Antarctic circumpolar frontal systems. Due to increased (multibeam) data coverage, IBCSO v2 significantly improves the overall representation of the Southern Ocean seafloor and resolves many submarine landforms in more detail. This makes IBCSO v2 the most authoritative seafloor map of the area south of 50°S.