Seismic Performance of Integral Abutment Highway Bridges in Illinois

The seismic behavior of integral abutment bridges (IABs) is of particular interest in southern Illinois, where proximity to the New Madrid Seismic Zone may create significant ground motion accelerations during an earthquake. IABs are common in modern bridge construction due to their lack of expansion joints between the superstructure and abutment, which leads to decreased environmental damage at the abutment seat when compared to stub abutment bridges. However, elimination of expansion joints can also lead to development of complex soil-structure-interaction limit states at the abutment and its foundation when an IAB is subjected to lateral loads. This report examines the seismic behavior of typical IABs in southern Illinois and develops feedback and recommendations for improving IAB seismic designs. This is accomplished through modeling IABs as a whole bridge system, subjecting the models to representative ground motions, monitoring the behavior of key IAB components, using the monitored results to form a comprehensive view of seismic behavior, and employing the developed knowledge to form recommendations for improving IAB seismic performance. IAB models are developed in OpenSees through nonlinear modeling of multiple components, as well as the connections between components, representing typical IAB designs for Illinois, and are then subjected to 1000-year return period hazard ground motions developed specifically for southern Illinois. Incremental dynamic analyses are also performed. IABs of varying superstructure materials, span configurations, bearing layouts, pier heights, and foundation soil conditions are dynamically analyzed using the sets of developed ground motions. Damage to pier columns is especially prominent in IABs with shorter piers and longer abutment-to-abutment spans, while abutment foundation damage in terms of yielding, local buckling, and rupture of the piles frequently occurs in many IAB variants. Recommendations on design modifications to improve the seismic behavior of IABs by limiting the level of damage to these components are also investigated through modifying elastomeric bearing side retainer strength, fixed bearing strength, pier column size, and backfill contributions.IDOT-R27-133Ope

Seismic Performance of Seat-Type Abutment Highway Bridges in Illinois

This study assesses the seismic performance of quasi-isolated highway bridges with seat-type abutments, validates the current IDOT design strategy, and provides recommendations for improving a bridge’s seismic behavior. To encompass common configurations of highway bridges with non-seismically designed bearing components employed as sacrificial connections between superstructures and substructures, a suite of prototype bridges with variations in span arrangement, girder type, skew angle, pier column height, and foundation soil condition were studied. Detailed three-dimensional nonlinear finite-element models were developed for the bridges, incorporating various critical structural components and geotechnical mechanisms. Multi-mode adaptive pushover analyses were conducted to investigate bridge response characteristics in terms of the force distribution among substructures, the sequence of limit state occurrences, the fusing of sacrificial connections, and the vulnerability of critical bridge components. Eigenvalue modal analyses were also performed in the elastic and inelastic deformation states to reveal modal response characteristics of the bridges. The study culminated in an extensive seismic performance assessment of quasi-isolated bridges, for which thousands of nonlinear dynamic time-history analyses were carried out. The bridges were subjected to a suite of site-specific earthquake ground motions, taking into account the site condition and the regional seismicity of Cairo, Illinois. Assessment results validated that the current quasi-isolation bridge design strategy is generally effective, and the majority of the studied prototype bridges are unlikely to fail in global collapse when subjected to horizontal earthquake ground motions with a 1,000-year return period in deep southern Illinois. Although most of the prototype bridges exhibited satisfactory seismic performance, the response of a small number of them demonstrated a risk of bearing unseating and severe pier column damage. With the aim of improving the seismic performance of these bridges, preliminary recommendations for calibrating the current design strategy were proposed, and their efficacy was demonstrated by comparative studies.IDOT-R27-133Ope

Modification of ground motions for use in Central North America: Southern Illinois surface ground motions for structural analysis

The lack of ground motion time history records with a 1000-year return period hazard for Central North America (CNA) often requires earthquake engineering researchers in the area to develop ground motions of their own. This report briefly describes a procedure for developing 1000-year return period ground motion time history records, and this procedure was applied for 10 sites in southern Illinois. Accompanying this report are 20 individual ground motion time history records developed at each of the 10 sites (for a total of 200 ground motions). These ground motions may be useful for various purposes including in dynamic structural analyses of bridges and other structures in southern Illinois (and potentially other CNA regions). The accompanying ground motions are developed following the detailed procedure presented in Kozak et al. [2017]. See "Has Parts" for persistent link to ground motion data files.Ope

Conformational Plasticity of proNGF

Nerve Growth Factor is an essential protein that supports neuronal survival during development and influences neuronal function throughout adulthood, both in the central and peripheral nervous system. The unprocessed precursor of NGF, proNGF, seems to be endowed with biological functions distinct from those of the mature protein, such as chaperone-like activities and apoptotic and/or neurotrophic properties. We have previously suggested, based on Small Angle X-ray Scattering data, that recombinant murine proNGF has features typical of an intrinsically unfolded protein. Using complementary biophysical techniques, we show here new evidence that clarifies and widens this hypothesis through a detailed comparison of the structural properties of NGF and proNGF. Our data provide direct information about the dynamic properties of the pro-peptide and indicate that proNGF assumes in solution a compact globular conformation. The N-terminal pro-peptide extension influences the chemical environment of the mature protein and protects the protein from proteolytic digestion. Accordingly, we observe that unfolding of proNGF involves a two-steps mechanism. The distinct structural properties of proNGF as compared to NGF agree with and rationalise a different functional role of the precursor

Secondary Organic Aerosol Composition from C₁₂ Alkanes

The effects of structure, NO_x conditions, relative humidity, and aerosol acidity on the chemical composition of secondary organic aerosol (SOA) are reported for the photooxidation of three C_(12) alkanes: n-dodecane, cyclododecane, and hexylcyclohexane. Acidity was modified through seed particle composition: NaCl, (NH_4)_2SO_4, and (NH_4)_2SO_4 + H_2SO_4. Off-line analysis of SOA was carried out by solvent extraction and gas chromatography–mass spectrometry (GC/MS) and direct analysis in real-time mass spectrometry. We report here 750 individual masses of SOA products identified from these three alkane systems and 324 isomers resolved by GC/MS analysis. The chemical compositions for each alkane system provide compelling evidence of particle-phase chemistry, including reactions leading to oligomer formation. Major oligomeric species for alkane SOA are peroxyhemiacetals, hemiacetals, esters, and aldol condensation products. Furans, dihydrofurans, hydroxycarbonyls, and their corresponding imine analogues are important participants in these oligomer-producing reactions. Imines are formed in the particle phase from the reaction of the ammonium sulfate seed aerosol with carbonyl-bearing compounds present in all the SOA systems. Under high-NO conditions, organonitrate products can lead to an increase of aerosol volume concentration by up to a factor of 5 over that in low-NO conditions. Structure was found to play a key role in determining the degree of functionalization and fragmentation of the parent alkane, influencing the mean molecular weight of the SOA produced and the mean atomic O:C ratio

Abnormal expression and processing of the proprotein convertases PC1 and PC2 in human colorectal liver metastases

BACKGROUND: The family of proprotein convertases has been recently implicated in tumorigenesis and metastasis in animal models. However, these studies have not yet been completely corroborated in human tumors. METHODS: Using RT PCR, immunoblot and immunohistochemistry we assessed the presence and the processing patterns of the convertases PC1 and PC2 as well as the PC2 specific chaperone 7B2 in human liver metastases originating from colorectal cancer and compared them to unaffected and normal liver. Furthermore, we assessed the presence and processing profiles of PC1, PC2 and 7B2 in primary colon cancers. RESULTS: mRNA, protein expression, and protein cleavage profiles of proprotein convertases 1 and 2 are altered in liver colorectal metastasis, compared to unaffected and normal liver. Active PC1 protein is overexpressed in tumor, correlating with its mRNA profile. Moreover, the enhanced PC2 processing pattern in tumor correlates with the overexpression of its specific binding protein 7B2. These results were corroborated by immunohistochemistry. The specific and uniform convertase pattern observed in the metastases was present only in a fraction of primary colon cancers. CONCLUSION: The uniformly altered proprotein convertase profile in liver metastases is observed only in a fraction of primary colon cancers, suggesting possible selection processes involving PCs during metastasis as well as an active role of PCs in liver metastasis. In addition, the exclusive presence of 7B2 in metastatic tumors may represent a new target for early diagnosis, prognosis and/or treatment

ALMA Observations of the DART Impact: Characterizing the Ejecta at Sub-Millimeter Wavelengths

We report observations of the Didymos-Dimorphos binary asteroid system using the Atacama Large Millimeter/Submillimeter Array (ALMA) and the Atacama Compact Array (ACA) in support of the Double Asteroid Redirection Test (DART) mission. Our observations on UT 2022 September 15 provided a pre-impact baseline and the first measure of Didymos-Dimorphos' spectral emissivity at $\lambda=0.87$ mm, which was consistent with the handful of siliceous and carbonaceous asteroids measured at millimeter wavelengths. Our post-impact observations were conducted using four consecutive executions each of ALMA and the ACA spanning from T$+$3.52 to T$+$8.60 hours post-impact, sampling thermal emission from the asteroids and the impact ejecta. We scaled our pre-impact baseline measurement and subtracted it from the post-impact observations to isolate the flux density of mm-sized grains in the ejecta. Ejecta dust masses were calculated for a range of materials that may be representative of Dimorphos' S-type asteroid material. The average ejecta mass over our observations is consistent with 1.3--6.4$\times10^7$ kg, with the lower and higher values calculated for amorphous silicates and for crystalline silicates, respectively. Owing to the likely crystalline nature of S-type asteroid material, the higher value is favored. These ejecta masses represent 0.3--1.5\% of Dimorphos' total mass and are in agreement with lower limits on the ejecta mass based on measurements at optical wavelengths. Our results provide the most sensitive measure of mm-sized material in the ejecta and demonstrate the power of ALMA for providing supporting observations to spaceflight missions

NGF and proNGF Regulate Functionally Distinct mRNAs in PC12 Cells: An Early Gene Expression Profiling

The biological activities of NGF and of its precursor proNGF are quite distinct, due to different receptor binding profiles, but little is known about how proNGF regulates gene expression. Whether proNGF is a purely pro-apoptotic molecule and/or simply a “less potent NGF” is still a matter of debate. We performed experiments to address this question, by verifying whether a proNGF specific transcriptional signature, distinct from that of NGF, could be identified. To this aim, we studied gene expression regulation by proNGF and NGF in PC12 cells incubated for 1 and 4 hours with recombinant NGF and proNGF, in its wild-type or in a furin-cleavage resistant form. mRNA expression profiles were analyzed by whole genome microarrays at early time points, in order to identify specific profiles of NGF and proNGF. Clear differences between the mRNA profiles modulated by the three neurotrophin forms were identified. NGF and proNGF modulate remarkably distinct mRNA expression patterns, with the gene expression profile regulated by NGF being significantly more complex than that by proNGF, both in terms of the total number of differentially expressed mRNAs and of the gene families involved. Moreover, while the total number of genes modulated by NGF increases dramatically with time, that by proNGFs is unchanged or reduced. We identified a subset of regulated genes that could be ascribed to a “pure proNGF” signalling, distinct from the “pure NGF” one. We also conclude that the composition of mixed NGF and proNGF samples, when the two proteins coexist, influences the profile of gene expression. Based on this comparison of the gene expression profiles regulated by NGF and its proNGF precursor, we conclude that the two proteins activate largely distinct transcriptional programs and that the ratio of NGF to proNGF in vivo can profoundly influence the pattern of regulated mRNAs